diff options
Diffstat (limited to 'library/ssl_msg.c')
| -rw-r--r-- | library/ssl_msg.c | 6368 |
1 files changed, 6368 insertions, 0 deletions
diff --git a/library/ssl_msg.c b/library/ssl_msg.c new file mode 100644 index 00000000000..b07cd96f1bc --- /dev/null +++ b/library/ssl_msg.c @@ -0,0 +1,6368 @@ +/* + * Generic SSL/TLS messaging layer functions + * (record layer + retransmission state machine) + * + * Copyright The Mbed TLS Contributors + * SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later + */ +/* + * http://www.ietf.org/rfc/rfc2246.txt + * http://www.ietf.org/rfc/rfc4346.txt + */ + +#include "common.h" + +#if defined(MBEDTLS_SSL_TLS_C) + +#include "mbedtls/platform.h" + +#include "mbedtls/ssl.h" +#include "ssl_misc.h" +#include "debug_internal.h" +#include "mbedtls/error.h" +#include "mbedtls/platform_util.h" +#include "mbedtls/version.h" +#include "constant_time_internal.h" +#include "mbedtls/constant_time.h" + +#include <string.h> + +#if defined(MBEDTLS_USE_PSA_CRYPTO) +#include "psa_util_internal.h" +#include "psa/crypto.h" +#endif + +#if defined(MBEDTLS_X509_CRT_PARSE_C) +#include "mbedtls/oid.h" +#endif + +#if defined(MBEDTLS_USE_PSA_CRYPTO) +/* Define a local translating function to save code size by not using too many + * arguments in each translating place. */ +static int local_err_translation(psa_status_t status) +{ + return psa_status_to_mbedtls(status, psa_to_ssl_errors, + ARRAY_LENGTH(psa_to_ssl_errors), + psa_generic_status_to_mbedtls); +} +#define PSA_TO_MBEDTLS_ERR(status) local_err_translation(status) +#endif + +#if defined(MBEDTLS_SSL_SOME_SUITES_USE_MAC) + +#if defined(MBEDTLS_USE_PSA_CRYPTO) + +#if defined(PSA_WANT_ALG_SHA_384) +#define MAX_HASH_BLOCK_LENGTH PSA_HASH_BLOCK_LENGTH(PSA_ALG_SHA_384) +#elif defined(PSA_WANT_ALG_SHA_256) +#define MAX_HASH_BLOCK_LENGTH PSA_HASH_BLOCK_LENGTH(PSA_ALG_SHA_256) +#else /* See check_config.h */ +#define MAX_HASH_BLOCK_LENGTH PSA_HASH_BLOCK_LENGTH(PSA_ALG_SHA_1) +#endif + +MBEDTLS_STATIC_TESTABLE +int mbedtls_ct_hmac(mbedtls_svc_key_id_t key, + psa_algorithm_t mac_alg, + const unsigned char *add_data, + size_t add_data_len, + const unsigned char *data, + size_t data_len_secret, + size_t min_data_len, + size_t max_data_len, + unsigned char *output) +{ + /* + * This function breaks the HMAC abstraction and uses psa_hash_clone() + * extension in order to get constant-flow behaviour. + * + * HMAC(msg) is defined as HASH(okey + HASH(ikey + msg)) where + means + * concatenation, and okey/ikey are the XOR of the key with some fixed bit + * patterns (see RFC 2104, sec. 2). + * + * We'll first compute ikey/okey, then inner_hash = HASH(ikey + msg) by + * hashing up to minlen, then cloning the context, and for each byte up + * to maxlen finishing up the hash computation, keeping only the + * correct result. + * + * Then we only need to compute HASH(okey + inner_hash) and we're done. + */ + psa_algorithm_t hash_alg = PSA_ALG_HMAC_GET_HASH(mac_alg); + const size_t block_size = PSA_HASH_BLOCK_LENGTH(hash_alg); + unsigned char key_buf[MAX_HASH_BLOCK_LENGTH]; + const size_t hash_size = PSA_HASH_LENGTH(hash_alg); + psa_hash_operation_t operation = PSA_HASH_OPERATION_INIT; + size_t hash_length; + + unsigned char aux_out[PSA_HASH_MAX_SIZE]; + psa_hash_operation_t aux_operation = PSA_HASH_OPERATION_INIT; + size_t offset; + psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED; + + size_t mac_key_length; + size_t i; + +#define PSA_CHK(func_call) \ + do { \ + status = (func_call); \ + if (status != PSA_SUCCESS) \ + goto cleanup; \ + } while (0) + + /* Export MAC key + * We assume key length is always exactly the output size + * which is never more than the block size, thus we use block_size + * as the key buffer size. + */ + PSA_CHK(psa_export_key(key, key_buf, block_size, &mac_key_length)); + + /* Calculate ikey */ + for (i = 0; i < mac_key_length; i++) { + key_buf[i] = (unsigned char) (key_buf[i] ^ 0x36); + } + for (; i < block_size; ++i) { + key_buf[i] = 0x36; + } + + PSA_CHK(psa_hash_setup(&operation, hash_alg)); + + /* Now compute inner_hash = HASH(ikey + msg) */ + PSA_CHK(psa_hash_update(&operation, key_buf, block_size)); + PSA_CHK(psa_hash_update(&operation, add_data, add_data_len)); + PSA_CHK(psa_hash_update(&operation, data, min_data_len)); + + /* Fill the hash buffer in advance with something that is + * not a valid hash (barring an attack on the hash and + * deliberately-crafted input), in case the caller doesn't + * check the return status properly. */ + memset(output, '!', hash_size); + + /* For each possible length, compute the hash up to that point */ + for (offset = min_data_len; offset <= max_data_len; offset++) { + PSA_CHK(psa_hash_clone(&operation, &aux_operation)); + PSA_CHK(psa_hash_finish(&aux_operation, aux_out, + PSA_HASH_MAX_SIZE, &hash_length)); + /* Keep only the correct inner_hash in the output buffer */ + mbedtls_ct_memcpy_if(mbedtls_ct_uint_eq(offset, data_len_secret), + output, aux_out, NULL, hash_size); + + if (offset < max_data_len) { + PSA_CHK(psa_hash_update(&operation, data + offset, 1)); + } + } + + /* Abort current operation to prepare for final operation */ + PSA_CHK(psa_hash_abort(&operation)); + + /* Calculate okey */ + for (i = 0; i < mac_key_length; i++) { + key_buf[i] = (unsigned char) ((key_buf[i] ^ 0x36) ^ 0x5C); + } + for (; i < block_size; ++i) { + key_buf[i] = 0x5C; + } + + /* Now compute HASH(okey + inner_hash) */ + PSA_CHK(psa_hash_setup(&operation, hash_alg)); + PSA_CHK(psa_hash_update(&operation, key_buf, block_size)); + PSA_CHK(psa_hash_update(&operation, output, hash_size)); + PSA_CHK(psa_hash_finish(&operation, output, hash_size, &hash_length)); + +#undef PSA_CHK + +cleanup: + mbedtls_platform_zeroize(key_buf, MAX_HASH_BLOCK_LENGTH); + mbedtls_platform_zeroize(aux_out, PSA_HASH_MAX_SIZE); + + psa_hash_abort(&operation); + psa_hash_abort(&aux_operation); + return PSA_TO_MBEDTLS_ERR(status); +} + +#undef MAX_HASH_BLOCK_LENGTH + +#else +MBEDTLS_STATIC_TESTABLE +int mbedtls_ct_hmac(mbedtls_md_context_t *ctx, + const unsigned char *add_data, + size_t add_data_len, + const unsigned char *data, + size_t data_len_secret, + size_t min_data_len, + size_t max_data_len, + unsigned char *output) +{ + /* + * This function breaks the HMAC abstraction and uses the md_clone() + * extension to the MD API in order to get constant-flow behaviour. + * + * HMAC(msg) is defined as HASH(okey + HASH(ikey + msg)) where + means + * concatenation, and okey/ikey are the XOR of the key with some fixed bit + * patterns (see RFC 2104, sec. 2), which are stored in ctx->hmac_ctx. + * + * We'll first compute inner_hash = HASH(ikey + msg) by hashing up to + * minlen, then cloning the context, and for each byte up to maxlen + * finishing up the hash computation, keeping only the correct result. + * + * Then we only need to compute HASH(okey + inner_hash) and we're done. + */ + const mbedtls_md_type_t md_alg = mbedtls_md_get_type(ctx->md_info); + /* TLS 1.2 only supports SHA-384, SHA-256, SHA-1, MD-5, + * all of which have the same block size except SHA-384. */ + const size_t block_size = md_alg == MBEDTLS_MD_SHA384 ? 128 : 64; + const unsigned char * const ikey = ctx->hmac_ctx; + const unsigned char * const okey = ikey + block_size; + const size_t hash_size = mbedtls_md_get_size(ctx->md_info); + + unsigned char aux_out[MBEDTLS_MD_MAX_SIZE]; + mbedtls_md_context_t aux; + size_t offset; + int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; + + mbedtls_md_init(&aux); + +#define MD_CHK(func_call) \ + do { \ + ret = (func_call); \ + if (ret != 0) \ + goto cleanup; \ + } while (0) + + MD_CHK(mbedtls_md_setup(&aux, ctx->md_info, 0)); + + /* After hmac_start() of hmac_reset(), ikey has already been hashed, + * so we can start directly with the message */ + MD_CHK(mbedtls_md_update(ctx, add_data, add_data_len)); + MD_CHK(mbedtls_md_update(ctx, data, min_data_len)); + + /* Fill the hash buffer in advance with something that is + * not a valid hash (barring an attack on the hash and + * deliberately-crafted input), in case the caller doesn't + * check the return status properly. */ + memset(output, '!', hash_size); + + /* For each possible length, compute the hash up to that point */ + for (offset = min_data_len; offset <= max_data_len; offset++) { + MD_CHK(mbedtls_md_clone(&aux, ctx)); + MD_CHK(mbedtls_md_finish(&aux, aux_out)); + /* Keep only the correct inner_hash in the output buffer */ + mbedtls_ct_memcpy_if(mbedtls_ct_uint_eq(offset, data_len_secret), + output, aux_out, NULL, hash_size); + + if (offset < max_data_len) { + MD_CHK(mbedtls_md_update(ctx, data + offset, 1)); + } + } + + /* The context needs to finish() before it starts() again */ + MD_CHK(mbedtls_md_finish(ctx, aux_out)); + + /* Now compute HASH(okey + inner_hash) */ + MD_CHK(mbedtls_md_starts(ctx)); + MD_CHK(mbedtls_md_update(ctx, okey, block_size)); + MD_CHK(mbedtls_md_update(ctx, output, hash_size)); + MD_CHK(mbedtls_md_finish(ctx, output)); + + /* Done, get ready for next time */ + MD_CHK(mbedtls_md_hmac_reset(ctx)); + +#undef MD_CHK + +cleanup: + mbedtls_md_free(&aux); + return ret; +} + +#endif /* MBEDTLS_USE_PSA_CRYPTO */ + +#endif /* MBEDTLS_SSL_SOME_SUITES_USE_MAC */ + +static uint32_t ssl_get_hs_total_len(mbedtls_ssl_context const *ssl); + +/* + * Start a timer. + * Passing millisecs = 0 cancels a running timer. + */ +void mbedtls_ssl_set_timer(mbedtls_ssl_context *ssl, uint32_t millisecs) +{ + if (ssl->f_set_timer == NULL) { + return; + } + + MBEDTLS_SSL_DEBUG_MSG(3, ("set_timer to %d ms", (int) millisecs)); + ssl->f_set_timer(ssl->p_timer, millisecs / 4, millisecs); +} + +/* + * Return -1 is timer is expired, 0 if it isn't. + */ +int mbedtls_ssl_check_timer(mbedtls_ssl_context *ssl) +{ + if (ssl->f_get_timer == NULL) { + return 0; + } + + if (ssl->f_get_timer(ssl->p_timer) == 2) { + MBEDTLS_SSL_DEBUG_MSG(3, ("timer expired")); + return -1; + } + + return 0; +} + +MBEDTLS_CHECK_RETURN_CRITICAL +static int ssl_parse_record_header(mbedtls_ssl_context const *ssl, + unsigned char *buf, + size_t len, + mbedtls_record *rec); + +int mbedtls_ssl_check_record(mbedtls_ssl_context const *ssl, + unsigned char *buf, + size_t buflen) +{ + int ret = 0; + MBEDTLS_SSL_DEBUG_MSG(1, ("=> mbedtls_ssl_check_record")); + MBEDTLS_SSL_DEBUG_BUF(3, "record buffer", buf, buflen); + + /* We don't support record checking in TLS because + * there doesn't seem to be a usecase for it. + */ + if (ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_STREAM) { + ret = MBEDTLS_ERR_SSL_FEATURE_UNAVAILABLE; + goto exit; + } +#if defined(MBEDTLS_SSL_PROTO_DTLS) + else { + mbedtls_record rec; + + ret = ssl_parse_record_header(ssl, buf, buflen, &rec); + if (ret != 0) { + MBEDTLS_SSL_DEBUG_RET(3, "ssl_parse_record_header", ret); + goto exit; + } + + if (ssl->transform_in != NULL) { + ret = mbedtls_ssl_decrypt_buf(ssl, ssl->transform_in, &rec); + if (ret != 0) { + MBEDTLS_SSL_DEBUG_RET(3, "mbedtls_ssl_decrypt_buf", ret); + goto exit; + } + } + } +#endif /* MBEDTLS_SSL_PROTO_DTLS */ + +exit: + /* On success, we have decrypted the buffer in-place, so make + * sure we don't leak any plaintext data. */ + mbedtls_platform_zeroize(buf, buflen); + + /* For the purpose of this API, treat messages with unexpected CID + * as well as such from future epochs as unexpected. */ + if (ret == MBEDTLS_ERR_SSL_UNEXPECTED_CID || + ret == MBEDTLS_ERR_SSL_EARLY_MESSAGE) { + ret = MBEDTLS_ERR_SSL_UNEXPECTED_RECORD; + } + + MBEDTLS_SSL_DEBUG_MSG(1, ("<= mbedtls_ssl_check_record")); + return ret; +} + +#define SSL_DONT_FORCE_FLUSH 0 +#define SSL_FORCE_FLUSH 1 + +#if defined(MBEDTLS_SSL_PROTO_DTLS) + +/* Forward declarations for functions related to message buffering. */ +static void ssl_buffering_free_slot(mbedtls_ssl_context *ssl, + uint8_t slot); +static void ssl_free_buffered_record(mbedtls_ssl_context *ssl); +MBEDTLS_CHECK_RETURN_CRITICAL +static int ssl_load_buffered_message(mbedtls_ssl_context *ssl); +MBEDTLS_CHECK_RETURN_CRITICAL +static int ssl_load_buffered_record(mbedtls_ssl_context *ssl); +MBEDTLS_CHECK_RETURN_CRITICAL +static int ssl_buffer_message(mbedtls_ssl_context *ssl); +MBEDTLS_CHECK_RETURN_CRITICAL +static int ssl_buffer_future_record(mbedtls_ssl_context *ssl, + mbedtls_record const *rec); +MBEDTLS_CHECK_RETURN_CRITICAL +static int ssl_next_record_is_in_datagram(mbedtls_ssl_context *ssl); + +static size_t ssl_get_maximum_datagram_size(mbedtls_ssl_context const *ssl) +{ + size_t mtu = mbedtls_ssl_get_current_mtu(ssl); +#if defined(MBEDTLS_SSL_VARIABLE_BUFFER_LENGTH) + size_t out_buf_len = ssl->out_buf_len; +#else + size_t out_buf_len = MBEDTLS_SSL_OUT_BUFFER_LEN; +#endif + + if (mtu != 0 && mtu < out_buf_len) { + return mtu; + } + + return out_buf_len; +} + +MBEDTLS_CHECK_RETURN_CRITICAL +static int ssl_get_remaining_space_in_datagram(mbedtls_ssl_context const *ssl) +{ + size_t const bytes_written = ssl->out_left; + size_t const mtu = ssl_get_maximum_datagram_size(ssl); + + /* Double-check that the write-index hasn't gone + * past what we can transmit in a single datagram. */ + if (bytes_written > mtu) { + /* Should never happen... */ + return MBEDTLS_ERR_SSL_INTERNAL_ERROR; + } + + return (int) (mtu - bytes_written); +} + +MBEDTLS_CHECK_RETURN_CRITICAL +static int ssl_get_remaining_payload_in_datagram(mbedtls_ssl_context const *ssl) +{ + int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; + size_t remaining, expansion; + size_t max_len = MBEDTLS_SSL_OUT_CONTENT_LEN; + +#if defined(MBEDTLS_SSL_MAX_FRAGMENT_LENGTH) + const size_t mfl = mbedtls_ssl_get_output_max_frag_len(ssl); + + if (max_len > mfl) { + max_len = mfl; + } + + /* By the standard (RFC 6066 Sect. 4), the MFL extension + * only limits the maximum record payload size, so in theory + * we would be allowed to pack multiple records of payload size + * MFL into a single datagram. However, this would mean that there's + * no way to explicitly communicate MTU restrictions to the peer. + * + * The following reduction of max_len makes sure that we never + * write datagrams larger than MFL + Record Expansion Overhead. + */ + if (max_len <= ssl->out_left) { + return 0; + } + + max_len -= ssl->out_left; +#endif + + ret = ssl_get_remaining_space_in_datagram(ssl); + if (ret < 0) { + return ret; + } + remaining = (size_t) ret; + + ret = mbedtls_ssl_get_record_expansion(ssl); + if (ret < 0) { + return ret; + } + expansion = (size_t) ret; + + if (remaining <= expansion) { + return 0; + } + + remaining -= expansion; + if (remaining >= max_len) { + remaining = max_len; + } + + return (int) remaining; +} + +/* + * Double the retransmit timeout value, within the allowed range, + * returning -1 if the maximum value has already been reached. + */ +MBEDTLS_CHECK_RETURN_CRITICAL +static int ssl_double_retransmit_timeout(mbedtls_ssl_context *ssl) +{ + uint32_t new_timeout; + + if (ssl->handshake->retransmit_timeout >= ssl->conf->hs_timeout_max) { + return -1; + } + + /* Implement the final paragraph of RFC 6347 section 4.1.1.1 + * in the following way: after the initial transmission and a first + * retransmission, back off to a temporary estimated MTU of 508 bytes. + * This value is guaranteed to be deliverable (if not guaranteed to be + * delivered) of any compliant IPv4 (and IPv6) network, and should work + * on most non-IP stacks too. */ + if (ssl->handshake->retransmit_timeout != ssl->conf->hs_timeout_min) { + ssl->handshake->mtu = 508; + MBEDTLS_SSL_DEBUG_MSG(2, ("mtu autoreduction to %d bytes", ssl->handshake->mtu)); + } + + new_timeout = 2 * ssl->handshake->retransmit_timeout; + + /* Avoid arithmetic overflow and range overflow */ + if (new_timeout < ssl->handshake->retransmit_timeout || + new_timeout > ssl->conf->hs_timeout_max) { + new_timeout = ssl->conf->hs_timeout_max; + } + + ssl->handshake->retransmit_timeout = new_timeout; + MBEDTLS_SSL_DEBUG_MSG(3, ("update timeout value to %lu millisecs", + (unsigned long) ssl->handshake->retransmit_timeout)); + + return 0; +} + +static void ssl_reset_retransmit_timeout(mbedtls_ssl_context *ssl) +{ + ssl->handshake->retransmit_timeout = ssl->conf->hs_timeout_min; + MBEDTLS_SSL_DEBUG_MSG(3, ("update timeout value to %lu millisecs", + (unsigned long) ssl->handshake->retransmit_timeout)); +} +#endif /* MBEDTLS_SSL_PROTO_DTLS */ + +/* + * Encryption/decryption functions + */ + +#if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID) || defined(MBEDTLS_SSL_PROTO_TLS1_3) + +static size_t ssl_compute_padding_length(size_t len, + size_t granularity) +{ + return (granularity - (len + 1) % granularity) % granularity; +} + +/* This functions transforms a (D)TLS plaintext fragment and a record content + * type into an instance of the (D)TLSInnerPlaintext structure. This is used + * in DTLS 1.2 + CID and within TLS 1.3 to allow flexible padding and to protect + * a record's content type. + * + * struct { + * opaque content[DTLSPlaintext.length]; + * ContentType real_type; + * uint8 zeros[length_of_padding]; + * } (D)TLSInnerPlaintext; + * + * Input: + * - `content`: The beginning of the buffer holding the + * plaintext to be wrapped. + * - `*content_size`: The length of the plaintext in Bytes. + * - `max_len`: The number of Bytes available starting from + * `content`. This must be `>= *content_size`. + * - `rec_type`: The desired record content type. + * + * Output: + * - `content`: The beginning of the resulting (D)TLSInnerPlaintext structure. + * - `*content_size`: The length of the resulting (D)TLSInnerPlaintext structure. + * + * Returns: + * - `0` on success. + * - A negative error code if `max_len` didn't offer enough space + * for the expansion. + */ +MBEDTLS_CHECK_RETURN_CRITICAL +static int ssl_build_inner_plaintext(unsigned char *content, + size_t *content_size, + size_t remaining, + uint8_t rec_type, + size_t pad) +{ + size_t len = *content_size; + + /* Write real content type */ + if (remaining == 0) { + return -1; + } + content[len] = rec_type; + len++; + remaining--; + + if (remaining < pad) { + return -1; + } + memset(content + len, 0, pad); + len += pad; + remaining -= pad; + + *content_size = len; + return 0; +} + +/* This function parses a (D)TLSInnerPlaintext structure. + * See ssl_build_inner_plaintext() for details. */ +MBEDTLS_CHECK_RETURN_CRITICAL +static int ssl_parse_inner_plaintext(unsigned char const *content, + size_t *content_size, + uint8_t *rec_type) +{ + size_t remaining = *content_size; + + /* Determine length of padding by skipping zeroes from the back. */ + do { + if (remaining == 0) { + return -1; + } + remaining--; + } while (content[remaining] == 0); + + *content_size = remaining; + *rec_type = content[remaining]; + + return 0; +} +#endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID || MBEDTLS_SSL_PROTO_TLS1_3 */ + +/* The size of the `add_data` structure depends on various + * factors, namely + * + * 1) CID functionality disabled + * + * additional_data = + * 8: seq_num + + * 1: type + + * 2: version + + * 2: length of inner plaintext + + * + * size = 13 bytes + * + * 2) CID functionality based on RFC 9146 enabled + * + * size = 8 + 1 + 1 + 1 + 2 + 2 + 6 + 2 + CID-length + * = 23 + CID-length + * + * 3) CID functionality based on legacy CID version + according to draft-ietf-tls-dtls-connection-id-05 + * https://tools.ietf.org/html/draft-ietf-tls-dtls-connection-id-05 + * + * size = 13 + 1 + CID-length + * + * More information about the CID usage: + * + * Per Section 5.3 of draft-ietf-tls-dtls-connection-id-05 the + * size of the additional data structure is calculated as: + * + * additional_data = + * 8: seq_num + + * 1: tls12_cid + + * 2: DTLSCipherText.version + + * n: cid + + * 1: cid_length + + * 2: length_of_DTLSInnerPlaintext + * + * Per RFC 9146 the size of the add_data structure is calculated as: + * + * additional_data = + * 8: seq_num_placeholder + + * 1: tls12_cid + + * 1: cid_length + + * 1: tls12_cid + + * 2: DTLSCiphertext.version + + * 2: epoch + + * 6: sequence_number + + * n: cid + + * 2: length_of_DTLSInnerPlaintext + * + */ +static void ssl_extract_add_data_from_record(unsigned char *add_data, + size_t *add_data_len, + mbedtls_record *rec, + mbedtls_ssl_protocol_version + tls_version, + size_t taglen) +{ + /* Several types of ciphers have been defined for use with TLS and DTLS, + * and the MAC calculations for those ciphers differ slightly. Further + * variants were added when the CID functionality was added with RFC 9146. + * This implementations also considers the use of a legacy version of the + * CID specification published in draft-ietf-tls-dtls-connection-id-05, + * which is used in deployments. + * + * We will distinguish between the non-CID and the CID cases below. + * + * --- Non-CID cases --- + * + * Quoting RFC 5246 (TLS 1.2): + * + * additional_data = seq_num + TLSCompressed.type + + * TLSCompressed.version + TLSCompressed.length; + * + * For TLS 1.3, the record sequence number is dropped from the AAD + * and encoded within the nonce of the AEAD operation instead. + * Moreover, the additional data involves the length of the TLS + * ciphertext, not the TLS plaintext as in earlier versions. + * Quoting RFC 8446 (TLS 1.3): + * + * additional_data = TLSCiphertext.opaque_type || + * TLSCiphertext.legacy_record_version || + * TLSCiphertext.length + * + * We pass the tag length to this function in order to compute the + * ciphertext length from the inner plaintext length rec->data_len via + * + * TLSCiphertext.length = TLSInnerPlaintext.length + taglen. + * + * --- CID cases --- + * + * RFC 9146 uses a common pattern when constructing the data + * passed into a MAC / AEAD cipher. + * + * Data concatenation for MACs used with block ciphers with + * Encrypt-then-MAC Processing (with CID): + * + * data = seq_num_placeholder + + * tls12_cid + + * cid_length + + * tls12_cid + + * DTLSCiphertext.version + + * epoch + + * sequence_number + + * cid + + * DTLSCiphertext.length + + * IV + + * ENC(content + padding + padding_length) + * + * Data concatenation for MACs used with block ciphers (with CID): + * + * data = seq_num_placeholder + + * tls12_cid + + * cid_length + + * tls12_cid + + * DTLSCiphertext.version + + * epoch + + * sequence_number + + * cid + + * length_of_DTLSInnerPlaintext + + * DTLSInnerPlaintext.content + + * DTLSInnerPlaintext.real_type + + * DTLSInnerPlaintext.zeros + * + * AEAD ciphers use the following additional data calculation (with CIDs): + * + * additional_data = seq_num_placeholder + + * tls12_cid + + * cid_length + + * tls12_cid + + * DTLSCiphertext.version + + * epoch + + * sequence_number + + * cid + + * length_of_DTLSInnerPlaintext + * + * Section 5.3 of draft-ietf-tls-dtls-connection-id-05 (for legacy CID use) + * defines the additional data calculation as follows: + * + * additional_data = seq_num + + * tls12_cid + + * DTLSCipherText.version + + * cid + + * cid_length + + * length_of_DTLSInnerPlaintext + */ + + unsigned char *cur = add_data; + size_t ad_len_field = rec->data_len; + +#if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID) && \ + MBEDTLS_SSL_DTLS_CONNECTION_ID_COMPAT == 0 + const unsigned char seq_num_placeholder[] = { 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff }; +#endif + +#if defined(MBEDTLS_SSL_PROTO_TLS1_3) + if (tls_version == MBEDTLS_SSL_VERSION_TLS1_3) { + /* In TLS 1.3, the AAD contains the length of the TLSCiphertext, + * which differs from the length of the TLSInnerPlaintext + * by the length of the authentication tag. */ + ad_len_field += taglen; + } else +#endif /* MBEDTLS_SSL_PROTO_TLS1_3 */ + { + ((void) tls_version); + ((void) taglen); + +#if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID) && \ + MBEDTLS_SSL_DTLS_CONNECTION_ID_COMPAT == 0 + if (rec->cid_len != 0) { + // seq_num_placeholder + memcpy(cur, seq_num_placeholder, sizeof(seq_num_placeholder)); + cur += sizeof(seq_num_placeholder); + + // tls12_cid type + *cur = rec->type; + cur++; + + // cid_length + *cur = rec->cid_len; + cur++; + } else +#endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID */ + { + // epoch + sequence number + memcpy(cur, rec->ctr, sizeof(rec->ctr)); + cur += sizeof(rec->ctr); + } + } + + // type + *cur = rec->type; + cur++; + + // version + memcpy(cur, rec->ver, sizeof(rec->ver)); + cur += sizeof(rec->ver); + +#if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID) && \ + MBEDTLS_SSL_DTLS_CONNECTION_ID_COMPAT == 1 + + if (rec->cid_len != 0) { + // CID + memcpy(cur, rec->cid, rec->cid_len); + cur += rec->cid_len; + + // cid_length + *cur = rec->cid_len; + cur++; + + // length of inner plaintext + MBEDTLS_PUT_UINT16_BE(ad_len_field, cur, 0); + cur += 2; + } else +#elif defined(MBEDTLS_SSL_DTLS_CONNECTION_ID) && \ + MBEDTLS_SSL_DTLS_CONNECTION_ID_COMPAT == 0 + + if (rec->cid_len != 0) { + // epoch + sequence number + memcpy(cur, rec->ctr, sizeof(rec->ctr)); + cur += sizeof(rec->ctr); + + // CID + memcpy(cur, rec->cid, rec->cid_len); + cur += rec->cid_len; + + // length of inner plaintext + MBEDTLS_PUT_UINT16_BE(ad_len_field, cur, 0); + cur += 2; + } else +#endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID */ + { + MBEDTLS_PUT_UINT16_BE(ad_len_field, cur, 0); + cur += 2; + } + + *add_data_len = (size_t) (cur - add_data); +} + +#if defined(MBEDTLS_SSL_HAVE_AEAD) +MBEDTLS_CHECK_RETURN_CRITICAL +static int ssl_transform_aead_dynamic_iv_is_explicit( + mbedtls_ssl_transform const *transform) +{ + return transform->ivlen != transform->fixed_ivlen; +} + +/* Compute IV := ( fixed_iv || 0 ) XOR ( 0 || dynamic_IV ) + * + * Concretely, this occurs in two variants: + * + * a) Fixed and dynamic IV lengths add up to total IV length, giving + * IV = fixed_iv || dynamic_iv + * + * This variant is used in TLS 1.2 when used with GCM or CCM. + * + * b) Fixed IV lengths matches total IV length, giving + * IV = fixed_iv XOR ( 0 || dynamic_iv ) + * + * This variant occurs in TLS 1.3 and for TLS 1.2 when using ChaChaPoly. + * + * See also the documentation of mbedtls_ssl_transform. + * + * This function has the precondition that + * + * dst_iv_len >= max( fixed_iv_len, dynamic_iv_len ) + * + * which has to be ensured by the caller. If this precondition + * violated, the behavior of this function is undefined. + */ +static void ssl_build_record_nonce(unsigned char *dst_iv, + size_t dst_iv_len, + unsigned char const *fixed_iv, + size_t fixed_iv_len, + unsigned char const *dynamic_iv, + size_t dynamic_iv_len) +{ + /* Start with Fixed IV || 0 */ + memset(dst_iv, 0, dst_iv_len); + memcpy(dst_iv, fixed_iv, fixed_iv_len); + + dst_iv += dst_iv_len - dynamic_iv_len; + mbedtls_xor(dst_iv, dst_iv, dynamic_iv, dynamic_iv_len); +} +#endif /* MBEDTLS_SSL_HAVE_AEAD */ + +int mbedtls_ssl_encrypt_buf(mbedtls_ssl_context *ssl, + mbedtls_ssl_transform *transform, + mbedtls_record *rec, + int (*f_rng)(void *, unsigned char *, size_t), + void *p_rng) +{ + mbedtls_ssl_mode_t ssl_mode; + int auth_done = 0; + unsigned char *data; + /* For an explanation of the additional data length see + * the description of ssl_extract_add_data_from_record(). + */ +#if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID) + unsigned char add_data[23 + MBEDTLS_SSL_CID_OUT_LEN_MAX]; +#else + unsigned char add_data[13]; +#endif + size_t add_data_len; + size_t post_avail; + + /* The SSL context is only used for debugging purposes! */ +#if !defined(MBEDTLS_DEBUG_C) + ssl = NULL; /* make sure we don't use it except for debug */ + ((void) ssl); +#endif + + /* The PRNG is used for dynamic IV generation that's used + * for CBC transformations in TLS 1.2. */ +#if !(defined(MBEDTLS_SSL_SOME_SUITES_USE_CBC) && \ + defined(MBEDTLS_SSL_PROTO_TLS1_2)) + ((void) f_rng); + ((void) p_rng); +#endif + + MBEDTLS_SSL_DEBUG_MSG(2, ("=> encrypt buf")); + + if (transform == NULL) { + MBEDTLS_SSL_DEBUG_MSG(1, ("no transform provided to encrypt_buf")); + return MBEDTLS_ERR_SSL_INTERNAL_ERROR; + } + if (rec == NULL + || rec->buf == NULL + || rec->buf_len < rec->data_offset + || rec->buf_len - rec->data_offset < rec->data_len +#if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID) + || rec->cid_len != 0 +#endif + ) { + MBEDTLS_SSL_DEBUG_MSG(1, ("bad record structure provided to encrypt_buf")); + return MBEDTLS_ERR_SSL_INTERNAL_ERROR; + } + + ssl_mode = mbedtls_ssl_get_mode_from_transform(transform); + + data = rec->buf + rec->data_offset; + post_avail = rec->buf_len - (rec->data_len + rec->data_offset); + MBEDTLS_SSL_DEBUG_BUF(4, "before encrypt: output payload", + data, rec->data_len); + + if (rec->data_len > MBEDTLS_SSL_OUT_CONTENT_LEN) { + MBEDTLS_SSL_DEBUG_MSG(1, ("Record content %" MBEDTLS_PRINTF_SIZET + " too large, maximum %" MBEDTLS_PRINTF_SIZET, + rec->data_len, + (size_t) MBEDTLS_SSL_OUT_CONTENT_LEN)); + return MBEDTLS_ERR_SSL_BAD_INPUT_DATA; + } + + /* The following two code paths implement the (D)TLSInnerPlaintext + * structure present in TLS 1.3 and DTLS 1.2 + CID. + * + * See ssl_build_inner_plaintext() for more information. + * + * Note that this changes `rec->data_len`, and hence + * `post_avail` needs to be recalculated afterwards. + * + * Note also that the two code paths cannot occur simultaneously + * since they apply to different versions of the protocol. There + * is hence no risk of double-addition of the inner plaintext. + */ +#if defined(MBEDTLS_SSL_PROTO_TLS1_3) + if (transform->tls_version == MBEDTLS_SSL_VERSION_TLS1_3) { + size_t padding = + ssl_compute_padding_length(rec->data_len, + MBEDTLS_SSL_CID_TLS1_3_PADDING_GRANULARITY); + if (ssl_build_inner_plaintext(data, + &rec->data_len, + post_avail, + rec->type, + padding) != 0) { + return MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL; + } + + rec->type = MBEDTLS_SSL_MSG_APPLICATION_DATA; + } +#endif /* MBEDTLS_SSL_PROTO_TLS1_3 */ + +#if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID) + /* + * Add CID information + */ + rec->cid_len = transform->out_cid_len; + memcpy(rec->cid, transform->out_cid, transform->out_cid_len); + MBEDTLS_SSL_DEBUG_BUF(3, "CID", rec->cid, rec->cid_len); + + if (rec->cid_len != 0) { + size_t padding = + ssl_compute_padding_length(rec->data_len, + MBEDTLS_SSL_CID_TLS1_3_PADDING_GRANULARITY); + /* + * Wrap plaintext into DTLSInnerPlaintext structure. + * See ssl_build_inner_plaintext() for more information. + * + * Note that this changes `rec->data_len`, and hence + * `post_avail` needs to be recalculated afterwards. + */ + if (ssl_build_inner_plaintext(data, + &rec->data_len, + post_avail, + rec->type, + padding) != 0) { + return MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL; + } + + rec->type = MBEDTLS_SSL_MSG_CID; + } +#endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID */ + + post_avail = rec->buf_len - (rec->data_len + rec->data_offset); + + /* + * Add MAC before if needed + */ +#if defined(MBEDTLS_SSL_SOME_SUITES_USE_MAC) + if (ssl_mode == MBEDTLS_SSL_MODE_STREAM || + ssl_mode == MBEDTLS_SSL_MODE_CBC) { + if (post_avail < transform->maclen) { + MBEDTLS_SSL_DEBUG_MSG(1, ("Buffer provided for encrypted record not large enough")); + return MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL; + } +#if defined(MBEDTLS_SSL_PROTO_TLS1_2) + unsigned char mac[MBEDTLS_SSL_MAC_ADD]; + int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; +#if defined(MBEDTLS_USE_PSA_CRYPTO) + psa_mac_operation_t operation = PSA_MAC_OPERATION_INIT; + psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED; + size_t sign_mac_length = 0; +#endif /* MBEDTLS_USE_PSA_CRYPTO */ + + ssl_extract_add_data_from_record(add_data, &add_data_len, rec, + transform->tls_version, + transform->taglen); + +#if defined(MBEDTLS_USE_PSA_CRYPTO) + status = psa_mac_sign_setup(&operation, transform->psa_mac_enc, + transform->psa_mac_alg); + if (status != PSA_SUCCESS) { + goto hmac_failed_etm_disabled; + } + + status = psa_mac_update(&operation, add_data, add_data_len); + if (status != PSA_SUCCESS) { + goto hmac_failed_etm_disabled; + } + + status = psa_mac_update(&operation, data, rec->data_len); + if (status != PSA_SUCCESS) { + goto hmac_failed_etm_disabled; + } + + status = psa_mac_sign_finish(&operation, mac, MBEDTLS_SSL_MAC_ADD, + &sign_mac_length); + if (status != PSA_SUCCESS) { + goto hmac_failed_etm_disabled; + } +#else + ret = mbedtls_md_hmac_update(&transform->md_ctx_enc, add_data, + add_data_len); + if (ret != 0) { + goto hmac_failed_etm_disabled; + } + ret = mbedtls_md_hmac_update(&transform->md_ctx_enc, data, rec->data_len); + if (ret != 0) { + goto hmac_failed_etm_disabled; + } + ret = mbedtls_md_hmac_finish(&transform->md_ctx_enc, mac); + if (ret != 0) { + goto hmac_failed_etm_disabled; + } + ret = mbedtls_md_hmac_reset(&transform->md_ctx_enc); + if (ret != 0) { + goto hmac_failed_etm_disabled; + } +#endif /* MBEDTLS_USE_PSA_CRYPTO */ + + memcpy(data + rec->data_len, mac, transform->maclen); +#endif + + MBEDTLS_SSL_DEBUG_BUF(4, "computed mac", data + rec->data_len, + transform->maclen); + + rec->data_len += transform->maclen; + post_avail -= transform->maclen; + auth_done++; + +hmac_failed_etm_disabled: + mbedtls_platform_zeroize(mac, transform->maclen); +#if defined(MBEDTLS_USE_PSA_CRYPTO) + ret = PSA_TO_MBEDTLS_ERR(status); + status = psa_mac_abort(&operation); + if (ret == 0 && status != PSA_SUCCESS) { + ret = PSA_TO_MBEDTLS_ERR(status); + } +#endif /* MBEDTLS_USE_PSA_CRYPTO */ + if (ret != 0) { + MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_md_hmac_xxx", ret); + return ret; + } + } +#endif /* MBEDTLS_SSL_SOME_SUITES_USE_MAC */ + + /* + * Encrypt + */ +#if defined(MBEDTLS_SSL_SOME_SUITES_USE_STREAM) + if (ssl_mode == MBEDTLS_SSL_MODE_STREAM) { + MBEDTLS_SSL_DEBUG_MSG(3, ("before encrypt: msglen = %" MBEDTLS_PRINTF_SIZET ", " + "including %d bytes of padding", + rec->data_len, 0)); + + /* The only supported stream cipher is "NULL", + * so there's nothing to do here.*/ + } else +#endif /* MBEDTLS_SSL_SOME_SUITES_USE_STREAM */ + +#if defined(MBEDTLS_SSL_HAVE_AEAD) + if (ssl_mode == MBEDTLS_SSL_MODE_AEAD) { + unsigned char iv[12]; + unsigned char *dynamic_iv; + size_t dynamic_iv_len; + int dynamic_iv_is_explicit = + ssl_transform_aead_dynamic_iv_is_explicit(transform); +#if defined(MBEDTLS_USE_PSA_CRYPTO) + psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED; +#endif /* MBEDTLS_USE_PSA_CRYPTO */ + int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; + + /* Check that there's space for the authentication tag. */ + if (post_avail < transform->taglen) { + MBEDTLS_SSL_DEBUG_MSG(1, ("Buffer provided for encrypted record not large enough")); + return MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL; + } + + /* + * Build nonce for AEAD encryption. + * + * Note: In the case of CCM and GCM in TLS 1.2, the dynamic + * part of the IV is prepended to the ciphertext and + * can be chosen freely - in particular, it need not + * agree with the record sequence number. + * However, since ChaChaPoly as well as all AEAD modes + * in TLS 1.3 use the record sequence number as the + * dynamic part of the nonce, we uniformly use the + * record sequence number here in all cases. + */ + dynamic_iv = rec->ctr; + dynamic_iv_len = sizeof(rec->ctr); + + ssl_build_record_nonce(iv, sizeof(iv), + transform->iv_enc, + transform->fixed_ivlen, + dynamic_iv, + dynamic_iv_len); + + /* + * Build additional data for AEAD encryption. + * This depends on the TLS version. + */ + ssl_extract_add_data_from_record(add_data, &add_data_len, rec, + transform->tls_version, + transform->taglen); + + MBEDTLS_SSL_DEBUG_BUF(4, "IV used (internal)", + iv, transform->ivlen); + MBEDTLS_SSL_DEBUG_BUF(4, "IV used (transmitted)", + dynamic_iv, + dynamic_iv_is_explicit ? dynamic_iv_len : 0); + MBEDTLS_SSL_DEBUG_BUF(4, "additional data used for AEAD", + add_data, add_data_len); + MBEDTLS_SSL_DEBUG_MSG(3, ("before encrypt: msglen = %" MBEDTLS_PRINTF_SIZET ", " + "including 0 bytes of padding", + rec->data_len)); + + /* + * Encrypt and authenticate + */ +#if defined(MBEDTLS_USE_PSA_CRYPTO) + status = psa_aead_encrypt(transform->psa_key_enc, + transform->psa_alg, + iv, transform->ivlen, + add_data, add_data_len, + data, rec->data_len, + data, rec->buf_len - (data - rec->buf), + &rec->data_len); + + if (status != PSA_SUCCESS) { + ret = PSA_TO_MBEDTLS_ERR(status); + MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_ssl_encrypt_buf", ret); + return ret; + } +#else + if ((ret = mbedtls_cipher_auth_encrypt_ext(&transform->cipher_ctx_enc, + iv, transform->ivlen, + add_data, add_data_len, + data, rec->data_len, /* src */ + data, rec->buf_len - (size_t) (data - rec->buf), /* dst */ + &rec->data_len, + transform->taglen)) != 0) { + MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_cipher_auth_encrypt_ext", ret); + return ret; + } +#endif /* MBEDTLS_USE_PSA_CRYPTO */ + + MBEDTLS_SSL_DEBUG_BUF(4, "after encrypt: tag", + data + rec->data_len - transform->taglen, + transform->taglen); + /* Account for authentication tag. */ + post_avail -= transform->taglen; + + /* + * Prefix record content with dynamic IV in case it is explicit. + */ + if (dynamic_iv_is_explicit != 0) { + if (rec->data_offset < dynamic_iv_len) { + MBEDTLS_SSL_DEBUG_MSG(1, ("Buffer provided for encrypted record not large enough")); + return MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL; + } + + memcpy(data - dynamic_iv_len, dynamic_iv, dynamic_iv_len); + rec->data_offset -= dynamic_iv_len; + rec->data_len += dynamic_iv_len; + } + + auth_done++; + } else +#endif /* MBEDTLS_SSL_HAVE_AEAD */ +#if defined(MBEDTLS_SSL_SOME_SUITES_USE_CBC) + if (ssl_mode == MBEDTLS_SSL_MODE_CBC || + ssl_mode == MBEDTLS_SSL_MODE_CBC_ETM) { + int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; + size_t padlen, i; + size_t olen; +#if defined(MBEDTLS_USE_PSA_CRYPTO) + psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED; + size_t part_len; + psa_cipher_operation_t cipher_op = PSA_CIPHER_OPERATION_INIT; +#endif /* MBEDTLS_USE_PSA_CRYPTO */ + + /* Currently we're always using minimal padding + * (up to 255 bytes would be allowed). */ + padlen = transform->ivlen - (rec->data_len + 1) % transform->ivlen; + if (padlen == transform->ivlen) { + padlen = 0; + } + + /* Check there's enough space in the buffer for the padding. */ + if (post_avail < padlen + 1) { + MBEDTLS_SSL_DEBUG_MSG(1, ("Buffer provided for encrypted record not large enough")); + return MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL; + } + + for (i = 0; i <= padlen; i++) { + data[rec->data_len + i] = (unsigned char) padlen; + } + + rec->data_len += padlen + 1; + post_avail -= padlen + 1; + +#if defined(MBEDTLS_SSL_PROTO_TLS1_2) + /* + * Prepend per-record IV for block cipher in TLS v1.2 as per + * Method 1 (6.2.3.2. in RFC4346 and RFC5246) + */ + if (f_rng == NULL) { + MBEDTLS_SSL_DEBUG_MSG(1, ("No PRNG provided to encrypt_record routine")); + return MBEDTLS_ERR_SSL_INTERNAL_ERROR; + } + + if (rec->data_offset < transform->ivlen) { + MBEDTLS_SSL_DEBUG_MSG(1, ("Buffer provided for encrypted record not large enough")); + return MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL; + } + + /* + * Generate IV + */ + ret = f_rng(p_rng, transform->iv_enc, transform->ivlen); + if (ret != 0) { + return ret; + } + + memcpy(data - transform->ivlen, transform->iv_enc, transform->ivlen); +#endif /* MBEDTLS_SSL_PROTO_TLS1_2 */ + + MBEDTLS_SSL_DEBUG_MSG(3, ("before encrypt: msglen = %" MBEDTLS_PRINTF_SIZET ", " + "including %" + MBEDTLS_PRINTF_SIZET + " bytes of IV and %" MBEDTLS_PRINTF_SIZET " bytes of padding", + rec->data_len, transform->ivlen, + padlen + 1)); + +#if defined(MBEDTLS_USE_PSA_CRYPTO) + status = psa_cipher_encrypt_setup(&cipher_op, + transform->psa_key_enc, transform->psa_alg); + + if (status != PSA_SUCCESS) { + ret = PSA_TO_MBEDTLS_ERR(status); + MBEDTLS_SSL_DEBUG_RET(1, "psa_cipher_encrypt_setup", ret); + return ret; + } + + status = psa_cipher_set_iv(&cipher_op, transform->iv_enc, transform->ivlen); + + if (status != PSA_SUCCESS) { + ret = PSA_TO_MBEDTLS_ERR(status); + MBEDTLS_SSL_DEBUG_RET(1, "psa_cipher_set_iv", ret); + return ret; + + } + + status = psa_cipher_update(&cipher_op, + data, rec->data_len, + data, rec->data_len, &olen); + + if (status != PSA_SUCCESS) { + ret = PSA_TO_MBEDTLS_ERR(status); + MBEDTLS_SSL_DEBUG_RET(1, "psa_cipher_update", ret); + return ret; + + } + + status = psa_cipher_finish(&cipher_op, + data + olen, rec->data_len - olen, + &part_len); + + if (status != PSA_SUCCESS) { + ret = PSA_TO_MBEDTLS_ERR(status); + MBEDTLS_SSL_DEBUG_RET(1, "psa_cipher_finish", ret); + return ret; + + } + + olen += part_len; +#else + if ((ret = mbedtls_cipher_crypt(&transform->cipher_ctx_enc, + transform->iv_enc, + transform->ivlen, + data, rec->data_len, + data, &olen)) != 0) { + MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_cipher_crypt", ret); + return ret; + } +#endif /* MBEDTLS_USE_PSA_CRYPTO */ + + if (rec->data_len != olen) { + MBEDTLS_SSL_DEBUG_MSG(1, ("should never happen")); + return MBEDTLS_ERR_SSL_INTERNAL_ERROR; + } + + data -= transform->ivlen; + rec->data_offset -= transform->ivlen; + rec->data_len += transform->ivlen; + +#if defined(MBEDTLS_SSL_ENCRYPT_THEN_MAC) + if (auth_done == 0) { + unsigned char mac[MBEDTLS_SSL_MAC_ADD]; +#if defined(MBEDTLS_USE_PSA_CRYPTO) + psa_mac_operation_t operation = PSA_MAC_OPERATION_INIT; + size_t sign_mac_length = 0; +#endif /* MBEDTLS_USE_PSA_CRYPTO */ + + /* MAC(MAC_write_key, add_data, IV, ENC(content + padding + padding_length)) + */ + + if (post_avail < transform->maclen) { + MBEDTLS_SSL_DEBUG_MSG(1, ("Buffer provided for encrypted record not large enough")); + return MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL; + } + + ssl_extract_add_data_from_record(add_data, &add_data_len, + rec, transform->tls_version, + transform->taglen); + + MBEDTLS_SSL_DEBUG_MSG(3, ("using encrypt then mac")); + MBEDTLS_SSL_DEBUG_BUF(4, "MAC'd meta-data", add_data, + add_data_len); +#if defined(MBEDTLS_USE_PSA_CRYPTO) + status = psa_mac_sign_setup(&operation, transform->psa_mac_enc, + transform->psa_mac_alg); + if (status != PSA_SUCCESS) { + goto hmac_failed_etm_enabled; + } + + status = psa_mac_update(&operation, add_data, add_data_len); + if (status != PSA_SUCCESS) { + goto hmac_failed_etm_enabled; + } + + status = psa_mac_update(&operation, data, rec->data_len); + if (status != PSA_SUCCESS) { + goto hmac_failed_etm_enabled; + } + + status = psa_mac_sign_finish(&operation, mac, MBEDTLS_SSL_MAC_ADD, + &sign_mac_length); + if (status != PSA_SUCCESS) { + goto hmac_failed_etm_enabled; + } +#else + + ret = mbedtls_md_hmac_update(&transform->md_ctx_enc, add_data, + add_data_len); + if (ret != 0) { + goto hmac_failed_etm_enabled; + } + ret = mbedtls_md_hmac_update(&transform->md_ctx_enc, + data, rec->data_len); + if (ret != 0) { + goto hmac_failed_etm_enabled; + } + ret = mbedtls_md_hmac_finish(&transform->md_ctx_enc, mac); + if (ret != 0) { + goto hmac_failed_etm_enabled; + } + ret = mbedtls_md_hmac_reset(&transform->md_ctx_enc); + if (ret != 0) { + goto hmac_failed_etm_enabled; + } +#endif /* MBEDTLS_USE_PSA_CRYPTO */ + + memcpy(data + rec->data_len, mac, transform->maclen); + + rec->data_len += transform->maclen; + post_avail -= transform->maclen; + auth_done++; + +hmac_failed_etm_enabled: + mbedtls_platform_zeroize(mac, transform->maclen); +#if defined(MBEDTLS_USE_PSA_CRYPTO) + ret = PSA_TO_MBEDTLS_ERR(status); + status = psa_mac_abort(&operation); + if (ret == 0 && status != PSA_SUCCESS) { + ret = PSA_TO_MBEDTLS_ERR(status); + } +#endif /* MBEDTLS_USE_PSA_CRYPTO */ + if (ret != 0) { + MBEDTLS_SSL_DEBUG_RET(1, "HMAC calculation failed", ret); + return ret; + } + } +#endif /* MBEDTLS_SSL_ENCRYPT_THEN_MAC */ + } else +#endif /* MBEDTLS_SSL_SOME_SUITES_USE_CBC) */ + { + MBEDTLS_SSL_DEBUG_MSG(1, ("should never happen")); + return MBEDTLS_ERR_SSL_INTERNAL_ERROR; + } + + /* Make extra sure authentication was performed, exactly once */ + if (auth_done != 1) { + MBEDTLS_SSL_DEBUG_MSG(1, ("should never happen")); + return MBEDTLS_ERR_SSL_INTERNAL_ERROR; + } + + MBEDTLS_SSL_DEBUG_MSG(2, ("<= encrypt buf")); + + return 0; +} + +int mbedtls_ssl_decrypt_buf(mbedtls_ssl_context const *ssl, + mbedtls_ssl_transform *transform, + mbedtls_record *rec) +{ +#if defined(MBEDTLS_SSL_SOME_SUITES_USE_CBC) || defined(MBEDTLS_SSL_HAVE_AEAD) + size_t olen; +#endif /* MBEDTLS_SSL_SOME_SUITES_USE_CBC || MBEDTLS_SSL_HAVE_AEAD */ + mbedtls_ssl_mode_t ssl_mode; + int ret; + + int auth_done = 0; +#if defined(MBEDTLS_SSL_SOME_SUITES_USE_MAC) + size_t padlen = 0; + mbedtls_ct_condition_t correct = MBEDTLS_CT_TRUE; +#endif + unsigned char *data; + /* For an explanation of the additional data length see + * the description of ssl_extract_add_data_from_record(). + */ +#if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID) + unsigned char add_data[23 + MBEDTLS_SSL_CID_IN_LEN_MAX]; +#else + unsigned char add_data[13]; +#endif + size_t add_data_len; + +#if !defined(MBEDTLS_DEBUG_C) + ssl = NULL; /* make sure we don't use it except for debug */ + ((void) ssl); +#endif + + MBEDTLS_SSL_DEBUG_MSG(2, ("=> decrypt buf")); + if (rec == NULL || + rec->buf == NULL || + rec->buf_len < rec->data_offset || + rec->buf_len - rec->data_offset < rec->data_len) { + MBEDTLS_SSL_DEBUG_MSG(1, ("bad record structure provided to decrypt_buf")); + return MBEDTLS_ERR_SSL_INTERNAL_ERROR; + } + + data = rec->buf + rec->data_offset; + ssl_mode = mbedtls_ssl_get_mode_from_transform(transform); + +#if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID) + /* + * Match record's CID with incoming CID. + */ + if (rec->cid_len != transform->in_cid_len || + memcmp(rec->cid, transform->in_cid, rec->cid_len) != 0) { + return MBEDTLS_ERR_SSL_UNEXPECTED_CID; + } +#endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID */ + +#if defined(MBEDTLS_SSL_SOME_SUITES_USE_STREAM) + if (ssl_mode == MBEDTLS_SSL_MODE_STREAM) { + if (rec->data_len < transform->maclen) { + MBEDTLS_SSL_DEBUG_MSG(1, + ("Record too short for MAC:" + " %" MBEDTLS_PRINTF_SIZET " < %" MBEDTLS_PRINTF_SIZET, + rec->data_len, transform->maclen)); + return MBEDTLS_ERR_SSL_INVALID_MAC; + } + + /* The only supported stream cipher is "NULL", + * so there's no encryption to do here.*/ + } else +#endif /* MBEDTLS_SSL_SOME_SUITES_USE_STREAM */ +#if defined(MBEDTLS_SSL_HAVE_AEAD) + if (ssl_mode == MBEDTLS_SSL_MODE_AEAD) { + unsigned char iv[12]; + unsigned char *dynamic_iv; + size_t dynamic_iv_len; +#if defined(MBEDTLS_USE_PSA_CRYPTO) + psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED; +#endif /* MBEDTLS_USE_PSA_CRYPTO */ + + /* + * Extract dynamic part of nonce for AEAD decryption. + * + * Note: In the case of CCM and GCM in TLS 1.2, the dynamic + * part of the IV is prepended to the ciphertext and + * can be chosen freely - in particular, it need not + * agree with the record sequence number. + */ + dynamic_iv_len = sizeof(rec->ctr); + if (ssl_transform_aead_dynamic_iv_is_explicit(transform) == 1) { + if (rec->data_len < dynamic_iv_len) { + MBEDTLS_SSL_DEBUG_MSG(1, ("msglen (%" MBEDTLS_PRINTF_SIZET + " ) < explicit_iv_len (%" MBEDTLS_PRINTF_SIZET ") ", + rec->data_len, + dynamic_iv_len)); + return MBEDTLS_ERR_SSL_INVALID_MAC; + } + dynamic_iv = data; + + data += dynamic_iv_len; + rec->data_offset += dynamic_iv_len; + rec->data_len -= dynamic_iv_len; + } else { + dynamic_iv = rec->ctr; + } + + /* Check that there's space for the authentication tag. */ + if (rec->data_len < transform->taglen) { + MBEDTLS_SSL_DEBUG_MSG(1, ("msglen (%" MBEDTLS_PRINTF_SIZET + ") < taglen (%" MBEDTLS_PRINTF_SIZET ") ", + rec->data_len, + transform->taglen)); + return MBEDTLS_ERR_SSL_INVALID_MAC; + } + rec->data_len -= transform->taglen; + + /* + * Prepare nonce from dynamic and static parts. + */ + ssl_build_record_nonce(iv, sizeof(iv), + transform->iv_dec, + transform->fixed_ivlen, + dynamic_iv, + dynamic_iv_len); + + /* + * Build additional data for AEAD encryption. + * This depends on the TLS version. + */ + ssl_extract_add_data_from_record(add_data, &add_data_len, rec, + transform->tls_version, + transform->taglen); + MBEDTLS_SSL_DEBUG_BUF(4, "additional data used for AEAD", + add_data, add_data_len); + + /* Because of the check above, we know that there are + * explicit_iv_len Bytes preceding data, and taglen + * bytes following data + data_len. This justifies + * the debug message and the invocation of + * mbedtls_cipher_auth_decrypt_ext() below. */ + + MBEDTLS_SSL_DEBUG_BUF(4, "IV used", iv, transform->ivlen); + MBEDTLS_SSL_DEBUG_BUF(4, "TAG used", data + rec->data_len, + transform->taglen); + + /* + * Decrypt and authenticate + */ +#if defined(MBEDTLS_USE_PSA_CRYPTO) + status = psa_aead_decrypt(transform->psa_key_dec, + transform->psa_alg, + iv, transform->ivlen, + add_data, add_data_len, + data, rec->data_len + transform->taglen, + data, rec->buf_len - (data - rec->buf), + &olen); + + if (status != PSA_SUCCESS) { + ret = PSA_TO_MBEDTLS_ERR(status); + MBEDTLS_SSL_DEBUG_RET(1, "psa_aead_decrypt", ret); + return ret; + } +#else + if ((ret = mbedtls_cipher_auth_decrypt_ext + (&transform->cipher_ctx_dec, + iv, transform->ivlen, + add_data, add_data_len, + data, rec->data_len + transform->taglen, /* src */ + data, rec->buf_len - (size_t) (data - rec->buf), &olen, /* dst */ + transform->taglen)) != 0) { + MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_cipher_auth_decrypt_ext", ret); + + if (ret == MBEDTLS_ERR_CIPHER_AUTH_FAILED) { + return MBEDTLS_ERR_SSL_INVALID_MAC; + } + + return ret; + } +#endif /* MBEDTLS_USE_PSA_CRYPTO */ + + auth_done++; + + /* Double-check that AEAD decryption doesn't change content length. */ + if (olen != rec->data_len) { + MBEDTLS_SSL_DEBUG_MSG(1, ("should never happen")); + return MBEDTLS_ERR_SSL_INTERNAL_ERROR; + } + } else +#endif /* MBEDTLS_SSL_HAVE_AEAD */ +#if defined(MBEDTLS_SSL_SOME_SUITES_USE_CBC) + if (ssl_mode == MBEDTLS_SSL_MODE_CBC || + ssl_mode == MBEDTLS_SSL_MODE_CBC_ETM) { + size_t minlen = 0; +#if defined(MBEDTLS_USE_PSA_CRYPTO) + psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED; + size_t part_len; + psa_cipher_operation_t cipher_op = PSA_CIPHER_OPERATION_INIT; +#endif /* MBEDTLS_USE_PSA_CRYPTO */ + + /* + * Check immediate ciphertext sanity + */ +#if defined(MBEDTLS_SSL_PROTO_TLS1_2) + /* The ciphertext is prefixed with the CBC IV. */ + minlen += transform->ivlen; +#endif + + /* Size considerations: + * + * - The CBC cipher text must not be empty and hence + * at least of size transform->ivlen. + * + * Together with the potential IV-prefix, this explains + * the first of the two checks below. + * + * - The record must contain a MAC, either in plain or + * encrypted, depending on whether Encrypt-then-MAC + * is used or not. + * - If it is, the message contains the IV-prefix, + * the CBC ciphertext, and the MAC. + * - If it is not, the padded plaintext, and hence + * the CBC ciphertext, has at least length maclen + 1 + * because there is at least the padding length byte. + * + * As the CBC ciphertext is not empty, both cases give the + * lower bound minlen + maclen + 1 on the record size, which + * we test for in the second check below. + */ + if (rec->data_len < minlen + transform->ivlen || + rec->data_len < minlen + transform->maclen + 1) { + MBEDTLS_SSL_DEBUG_MSG(1, ("msglen (%" MBEDTLS_PRINTF_SIZET + ") < max( ivlen(%" MBEDTLS_PRINTF_SIZET + "), maclen (%" MBEDTLS_PRINTF_SIZET ") " + "+ 1 ) ( + expl IV )", + rec->data_len, + transform->ivlen, + transform->maclen)); + return MBEDTLS_ERR_SSL_INVALID_MAC; + } + + /* + * Authenticate before decrypt if enabled + */ +#if defined(MBEDTLS_SSL_ENCRYPT_THEN_MAC) + if (ssl_mode == MBEDTLS_SSL_MODE_CBC_ETM) { +#if defined(MBEDTLS_USE_PSA_CRYPTO) + psa_mac_operation_t operation = PSA_MAC_OPERATION_INIT; +#else + unsigned char mac_expect[MBEDTLS_SSL_MAC_ADD]; +#endif /* MBEDTLS_USE_PSA_CRYPTO */ + + MBEDTLS_SSL_DEBUG_MSG(3, ("using encrypt then mac")); + + /* Update data_len in tandem with add_data. + * + * The subtraction is safe because of the previous check + * data_len >= minlen + maclen + 1. + * + * Afterwards, we know that data + data_len is followed by at + * least maclen Bytes, which justifies the call to + * mbedtls_ct_memcmp() below. + * + * Further, we still know that data_len > minlen */ + rec->data_len -= transform->maclen; + ssl_extract_add_data_from_record(add_data, &add_data_len, rec, + transform->tls_version, + transform->taglen); + + /* Calculate expected MAC. */ + MBEDTLS_SSL_DEBUG_BUF(4, "MAC'd meta-data", add_data, + add_data_len); +#if defined(MBEDTLS_USE_PSA_CRYPTO) + status = psa_mac_verify_setup(&operation, transform->psa_mac_dec, + transform->psa_mac_alg); + if (status != PSA_SUCCESS) { + goto hmac_failed_etm_enabled; + } + + status = psa_mac_update(&operation, add_data, add_data_len); + if (status != PSA_SUCCESS) { + goto hmac_failed_etm_enabled; + } + + status = psa_mac_update(&operation, data, rec->data_len); + if (status != PSA_SUCCESS) { + goto hmac_failed_etm_enabled; + } + + /* Compare expected MAC with MAC at the end of the record. */ + status = psa_mac_verify_finish(&operation, data + rec->data_len, + transform->maclen); + if (status != PSA_SUCCESS) { + goto hmac_failed_etm_enabled; + } +#else + ret = mbedtls_md_hmac_update(&transform->md_ctx_dec, add_data, + add_data_len); + if (ret != 0) { + goto hmac_failed_etm_enabled; + } + ret = mbedtls_md_hmac_update(&transform->md_ctx_dec, + data, rec->data_len); + if (ret != 0) { + goto hmac_failed_etm_enabled; + } + ret = mbedtls_md_hmac_finish(&transform->md_ctx_dec, mac_expect); + if (ret != 0) { + goto hmac_failed_etm_enabled; + } + ret = mbedtls_md_hmac_reset(&transform->md_ctx_dec); + if (ret != 0) { + goto hmac_failed_etm_enabled; + } + + MBEDTLS_SSL_DEBUG_BUF(4, "message mac", data + rec->data_len, + transform->maclen); + MBEDTLS_SSL_DEBUG_BUF(4, "expected mac", mac_expect, + transform->maclen); + + /* Compare expected MAC with MAC at the end of the record. */ + if (mbedtls_ct_memcmp(data + rec->data_len, mac_expect, + transform->maclen) != 0) { + MBEDTLS_SSL_DEBUG_MSG(1, ("message mac does not match")); + ret = MBEDTLS_ERR_SSL_INVALID_MAC; + goto hmac_failed_etm_enabled; + } +#endif /* MBEDTLS_USE_PSA_CRYPTO */ + auth_done++; + +hmac_failed_etm_enabled: +#if defined(MBEDTLS_USE_PSA_CRYPTO) + ret = PSA_TO_MBEDTLS_ERR(status); + status = psa_mac_abort(&operation); + if (ret == 0 && status != PSA_SUCCESS) { + ret = PSA_TO_MBEDTLS_ERR(status); + } +#else + mbedtls_platform_zeroize(mac_expect, transform->maclen); +#endif /* MBEDTLS_USE_PSA_CRYPTO */ + if (ret != 0) { + if (ret != MBEDTLS_ERR_SSL_INVALID_MAC) { + MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_hmac_xxx", ret); + } + return ret; + } + } +#endif /* MBEDTLS_SSL_ENCRYPT_THEN_MAC */ + + /* + * Check length sanity + */ + + /* We know from above that data_len > minlen >= 0, + * so the following check in particular implies that + * data_len >= minlen + ivlen ( = minlen or 2 * minlen ). */ + if (rec->data_len % transform->ivlen != 0) { + MBEDTLS_SSL_DEBUG_MSG(1, ("msglen (%" MBEDTLS_PRINTF_SIZET + ") %% ivlen (%" MBEDTLS_PRINTF_SIZET ") != 0", + rec->data_len, transform->ivlen)); + return MBEDTLS_ERR_SSL_INVALID_MAC; + } + +#if defined(MBEDTLS_SSL_PROTO_TLS1_2) + /* + * Initialize for prepended IV for block cipher in TLS v1.2 + */ + /* Safe because data_len >= minlen + ivlen = 2 * ivlen. */ + memcpy(transform->iv_dec, data, transform->ivlen); + + data += transform->ivlen; + rec->data_offset += transform->ivlen; + rec->data_len -= transform->ivlen; +#endif /* MBEDTLS_SSL_PROTO_TLS1_2 */ + + /* We still have data_len % ivlen == 0 and data_len >= ivlen here. */ + +#if defined(MBEDTLS_USE_PSA_CRYPTO) + status = psa_cipher_decrypt_setup(&cipher_op, + transform->psa_key_dec, transform->psa_alg); + + if (status != PSA_SUCCESS) { + ret = PSA_TO_MBEDTLS_ERR(status); + MBEDTLS_SSL_DEBUG_RET(1, "psa_cipher_decrypt_setup", ret); + return ret; + } + + status = psa_cipher_set_iv(&cipher_op, transform->iv_dec, transform->ivlen); + + if (status != PSA_SUCCESS) { + ret = PSA_TO_MBEDTLS_ERR(status); + MBEDTLS_SSL_DEBUG_RET(1, "psa_cipher_set_iv", ret); + return ret; + } + + status = psa_cipher_update(&cipher_op, + data, rec->data_len, + data, rec->data_len, &olen); + + if (status != PSA_SUCCESS) { + ret = PSA_TO_MBEDTLS_ERR(status); + MBEDTLS_SSL_DEBUG_RET(1, "psa_cipher_update", ret); + return ret; + } + + status = psa_cipher_finish(&cipher_op, + data + olen, rec->data_len - olen, + &part_len); + + if (status != PSA_SUCCESS) { + ret = PSA_TO_MBEDTLS_ERR(status); + MBEDTLS_SSL_DEBUG_RET(1, "psa_cipher_finish", ret); + return ret; + } + + olen += part_len; +#else + + if ((ret = mbedtls_cipher_crypt(&transform->cipher_ctx_dec, + transform->iv_dec, transform->ivlen, + data, rec->data_len, data, &olen)) != 0) { + MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_cipher_crypt", ret); + return ret; + } +#endif /* MBEDTLS_USE_PSA_CRYPTO */ + + /* Double-check that length hasn't changed during decryption. */ + if (rec->data_len != olen) { + MBEDTLS_SSL_DEBUG_MSG(1, ("should never happen")); + return MBEDTLS_ERR_SSL_INTERNAL_ERROR; + } + + /* Safe since data_len >= minlen + maclen + 1, so after having + * subtracted at most minlen and maclen up to this point, + * data_len > 0 (because of data_len % ivlen == 0, it's actually + * >= ivlen ). */ + padlen = data[rec->data_len - 1]; + + if (auth_done == 1) { + const mbedtls_ct_condition_t ge = mbedtls_ct_uint_ge( + rec->data_len, + padlen + 1); + correct = mbedtls_ct_bool_and(ge, correct); + padlen = mbedtls_ct_size_if_else_0(ge, padlen); + } else { +#if defined(MBEDTLS_SSL_DEBUG_ALL) + if (rec->data_len < transform->maclen + padlen + 1) { + MBEDTLS_SSL_DEBUG_MSG(1, ("msglen (%" MBEDTLS_PRINTF_SIZET + ") < maclen (%" MBEDTLS_PRINTF_SIZET + ") + padlen (%" MBEDTLS_PRINTF_SIZET ")", + rec->data_len, + transform->maclen, + padlen + 1)); + } +#endif + const mbedtls_ct_condition_t ge = mbedtls_ct_uint_ge( + rec->data_len, + transform->maclen + padlen + 1); + correct = mbedtls_ct_bool_and(ge, correct); + padlen = mbedtls_ct_size_if_else_0(ge, padlen); + } + + padlen++; + + /* Regardless of the validity of the padding, + * we have data_len >= padlen here. */ + +#if defined(MBEDTLS_SSL_PROTO_TLS1_2) + /* The padding check involves a series of up to 256 + * consecutive memory reads at the end of the record + * plaintext buffer. In order to hide the length and + * validity of the padding, always perform exactly + * `min(256,plaintext_len)` reads (but take into account + * only the last `padlen` bytes for the padding check). */ + size_t pad_count = 0; + volatile unsigned char * const check = data; + + /* Index of first padding byte; it has been ensured above + * that the subtraction is safe. */ + size_t const padding_idx = rec->data_len - padlen; + size_t const num_checks = rec->data_len <= 256 ? rec->data_len : 256; + size_t const start_idx = rec->data_len - num_checks; + size_t idx; + + for (idx = start_idx; idx < rec->data_len; idx++) { + /* pad_count += (idx >= padding_idx) && + * (check[idx] == padlen - 1); + */ + const mbedtls_ct_condition_t a = mbedtls_ct_uint_ge(idx, padding_idx); + size_t increment = mbedtls_ct_size_if_else_0(a, 1); + const mbedtls_ct_condition_t b = mbedtls_ct_uint_eq(check[idx], padlen - 1); + increment = mbedtls_ct_size_if_else_0(b, increment); + pad_count += increment; + } + correct = mbedtls_ct_bool_and(mbedtls_ct_uint_eq(pad_count, padlen), correct); + +#if defined(MBEDTLS_SSL_DEBUG_ALL) + if (padlen > 0 && correct == MBEDTLS_CT_FALSE) { + MBEDTLS_SSL_DEBUG_MSG(1, ("bad padding byte detected")); + } +#endif + padlen = mbedtls_ct_size_if_else_0(correct, padlen); + +#endif /* MBEDTLS_SSL_PROTO_TLS1_2 */ + + /* If the padding was found to be invalid, padlen == 0 + * and the subtraction is safe. If the padding was found valid, + * padlen hasn't been changed and the previous assertion + * data_len >= padlen still holds. */ + rec->data_len -= padlen; + } else +#endif /* MBEDTLS_SSL_SOME_SUITES_USE_CBC */ + { + MBEDTLS_SSL_DEBUG_MSG(1, ("should never happen")); + return MBEDTLS_ERR_SSL_INTERNAL_ERROR; + } + +#if defined(MBEDTLS_SSL_DEBUG_ALL) + MBEDTLS_SSL_DEBUG_BUF(4, "raw buffer after decryption", + data, rec->data_len); +#endif + + /* + * Authenticate if not done yet. + * Compute the MAC regardless of the padding result (RFC4346, CBCTIME). + */ +#if defined(MBEDTLS_SSL_SOME_SUITES_USE_MAC) + if (auth_done == 0) { + unsigned char mac_expect[MBEDTLS_SSL_MAC_ADD] = { 0 }; + unsigned char mac_peer[MBEDTLS_SSL_MAC_ADD] = { 0 }; + + /* For CBC+MAC, If the initial value of padlen was such that + * data_len < maclen + padlen + 1, then padlen + * got reset to 1, and the initial check + * data_len >= minlen + maclen + 1 + * guarantees that at this point we still + * have at least data_len >= maclen. + * + * If the initial value of padlen was such that + * data_len >= maclen + padlen + 1, then we have + * subtracted either padlen + 1 (if the padding was correct) + * or 0 (if the padding was incorrect) since then, + * hence data_len >= maclen in any case. + * + * For stream ciphers, we checked above that + * data_len >= maclen. + */ + rec->data_len -= transform->maclen; + ssl_extract_add_data_from_record(add_data, &add_data_len, rec, + transform->tls_version, + transform->taglen); + +#if defined(MBEDTLS_SSL_PROTO_TLS1_2) + /* + * The next two sizes are the minimum and maximum values of + * data_len over all padlen values. + * + * They're independent of padlen, since we previously did + * data_len -= padlen. + * + * Note that max_len + maclen is never more than the buffer + * length, as we previously did in_msglen -= maclen too. + */ + const size_t max_len = rec->data_len + padlen; + const size_t min_len = (max_len > 256) ? max_len - 256 : 0; + +#if defined(MBEDTLS_USE_PSA_CRYPTO) + ret = mbedtls_ct_hmac(transform->psa_mac_dec, + transform->psa_mac_alg, + add_data, add_data_len, + data, rec->data_len, min_len, max_len, + mac_expect); +#else + ret = mbedtls_ct_hmac(&transform->md_ctx_dec, + add_data, add_data_len, + data, rec->data_len, min_len, max_len, + mac_expect); +#endif /* MBEDTLS_USE_PSA_CRYPTO */ + if (ret != 0) { + MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_ct_hmac", ret); + goto hmac_failed_etm_disabled; + } + + mbedtls_ct_memcpy_offset(mac_peer, data, + rec->data_len, + min_len, max_len, + transform->maclen); +#endif /* MBEDTLS_SSL_PROTO_TLS1_2 */ + +#if defined(MBEDTLS_SSL_DEBUG_ALL) + MBEDTLS_SSL_DEBUG_BUF(4, "expected mac", mac_expect, transform->maclen); + MBEDTLS_SSL_DEBUG_BUF(4, "message mac", mac_peer, transform->maclen); +#endif + + if (mbedtls_ct_memcmp(mac_peer, mac_expect, + transform->maclen) != 0) { +#if defined(MBEDTLS_SSL_DEBUG_ALL) + MBEDTLS_SSL_DEBUG_MSG(1, ("message mac does not match")); +#endif + correct = MBEDTLS_CT_FALSE; + } + auth_done++; + +hmac_failed_etm_disabled: + mbedtls_platform_zeroize(mac_peer, transform->maclen); + mbedtls_platform_zeroize(mac_expect, transform->maclen); + if (ret != 0) { + return ret; + } + } + + /* + * Finally check the correct flag + */ + if (correct == MBEDTLS_CT_FALSE) { + return MBEDTLS_ERR_SSL_INVALID_MAC; + } +#endif /* MBEDTLS_SSL_SOME_SUITES_USE_MAC */ + + /* Make extra sure authentication was performed, exactly once */ + if (auth_done != 1) { + MBEDTLS_SSL_DEBUG_MSG(1, ("should never happen")); + return MBEDTLS_ERR_SSL_INTERNAL_ERROR; + } + +#if defined(MBEDTLS_SSL_PROTO_TLS1_3) + if (transform->tls_version == MBEDTLS_SSL_VERSION_TLS1_3) { + /* Remove inner padding and infer true content type. */ + ret = ssl_parse_inner_plaintext(data, &rec->data_len, + &rec->type); + + if (ret != 0) { + return MBEDTLS_ERR_SSL_INVALID_RECORD; + } + } +#endif /* MBEDTLS_SSL_PROTO_TLS1_3 */ + +#if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID) + if (rec->cid_len != 0) { + ret = ssl_parse_inner_plaintext(data, &rec->data_len, + &rec->type); + if (ret != 0) { + return MBEDTLS_ERR_SSL_INVALID_RECORD; + } + } +#endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID */ + + MBEDTLS_SSL_DEBUG_MSG(2, ("<= decrypt buf")); + + return 0; +} + +#undef MAC_NONE +#undef MAC_PLAINTEXT +#undef MAC_CIPHERTEXT + +/* + * Fill the input message buffer by appending data to it. + * The amount of data already fetched is in ssl->in_left. + * + * If we return 0, is it guaranteed that (at least) nb_want bytes are + * available (from this read and/or a previous one). Otherwise, an error code + * is returned (possibly EOF or WANT_READ). + * + * With stream transport (TLS) on success ssl->in_left == nb_want, but + * with datagram transport (DTLS) on success ssl->in_left >= nb_want, + * since we always read a whole datagram at once. + * + * For DTLS, it is up to the caller to set ssl->next_record_offset when + * they're done reading a record. + */ +int mbedtls_ssl_fetch_input(mbedtls_ssl_context *ssl, size_t nb_want) +{ + int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; + size_t len; +#if defined(MBEDTLS_SSL_VARIABLE_BUFFER_LENGTH) + size_t in_buf_len = ssl->in_buf_len; +#else + size_t in_buf_len = MBEDTLS_SSL_IN_BUFFER_LEN; +#endif + + MBEDTLS_SSL_DEBUG_MSG(2, ("=> fetch input")); + + if (ssl->f_recv == NULL && ssl->f_recv_timeout == NULL) { + MBEDTLS_SSL_DEBUG_MSG(1, ("Bad usage of mbedtls_ssl_set_bio() ")); + return MBEDTLS_ERR_SSL_BAD_INPUT_DATA; + } + + if (nb_want > in_buf_len - (size_t) (ssl->in_hdr - ssl->in_buf)) { + MBEDTLS_SSL_DEBUG_MSG(1, ("requesting more data than fits")); + return MBEDTLS_ERR_SSL_BAD_INPUT_DATA; + } + +#if defined(MBEDTLS_SSL_PROTO_DTLS) + if (ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM) { + uint32_t timeout; + + /* + * The point is, we need to always read a full datagram at once, so we + * sometimes read more then requested, and handle the additional data. + * It could be the rest of the current record (while fetching the + * header) and/or some other records in the same datagram. + */ + + /* + * Move to the next record in the already read datagram if applicable + */ + if (ssl->next_record_offset != 0) { + if (ssl->in_left < ssl->next_record_offset) { + MBEDTLS_SSL_DEBUG_MSG(1, ("should never happen")); + return MBEDTLS_ERR_SSL_INTERNAL_ERROR; + } + + ssl->in_left -= ssl->next_record_offset; + + if (ssl->in_left != 0) { + MBEDTLS_SSL_DEBUG_MSG(2, ("next record in same datagram, offset: %" + MBEDTLS_PRINTF_SIZET, + ssl->next_record_offset)); + memmove(ssl->in_hdr, + ssl->in_hdr + ssl->next_record_offset, + ssl->in_left); + } + + ssl->next_record_offset = 0; + } + + MBEDTLS_SSL_DEBUG_MSG(2, ("in_left: %" MBEDTLS_PRINTF_SIZET + ", nb_want: %" MBEDTLS_PRINTF_SIZET, + ssl->in_left, nb_want)); + + /* + * Done if we already have enough data. + */ + if (nb_want <= ssl->in_left) { + MBEDTLS_SSL_DEBUG_MSG(2, ("<= fetch input")); + return 0; + } + + /* + * A record can't be split across datagrams. If we need to read but + * are not at the beginning of a new record, the caller did something + * wrong. + */ + if (ssl->in_left != 0) { + MBEDTLS_SSL_DEBUG_MSG(1, ("should never happen")); + return MBEDTLS_ERR_SSL_INTERNAL_ERROR; + } + + /* + * Don't even try to read if time's out already. + * This avoids by-passing the timer when repeatedly receiving messages + * that will end up being dropped. + */ + if (mbedtls_ssl_check_timer(ssl) != 0) { + MBEDTLS_SSL_DEBUG_MSG(2, ("timer has expired")); + ret = MBEDTLS_ERR_SSL_TIMEOUT; + } else { + len = in_buf_len - (size_t) (ssl->in_hdr - ssl->in_buf); + + if (mbedtls_ssl_is_handshake_over(ssl) == 0) { + timeout = ssl->handshake->retransmit_timeout; + } else { + timeout = ssl->conf->read_timeout; + } + + MBEDTLS_SSL_DEBUG_MSG(3, ("f_recv_timeout: %lu ms", (unsigned long) timeout)); + + if (ssl->f_recv_timeout != NULL) { + ret = ssl->f_recv_timeout(ssl->p_bio, ssl->in_hdr, len, + timeout); + } else { + ret = ssl->f_recv(ssl->p_bio, ssl->in_hdr, len); + } + + MBEDTLS_SSL_DEBUG_RET(2, "ssl->f_recv(_timeout)", ret); + + if (ret == 0) { + return MBEDTLS_ERR_SSL_CONN_EOF; + } + } + + if (ret == MBEDTLS_ERR_SSL_TIMEOUT) { + MBEDTLS_SSL_DEBUG_MSG(2, ("timeout")); + mbedtls_ssl_set_timer(ssl, 0); + + if (ssl->state != MBEDTLS_SSL_HANDSHAKE_OVER) { + if (ssl_double_retransmit_timeout(ssl) != 0) { + MBEDTLS_SSL_DEBUG_MSG(1, ("handshake timeout")); + return MBEDTLS_ERR_SSL_TIMEOUT; + } + + if ((ret = mbedtls_ssl_resend(ssl)) != 0) { + MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_ssl_resend", ret); + return ret; + } + + return MBEDTLS_ERR_SSL_WANT_READ; + } +#if defined(MBEDTLS_SSL_SRV_C) && defined(MBEDTLS_SSL_RENEGOTIATION) + else if (ssl->conf->endpoint == MBEDTLS_SSL_IS_SERVER && + ssl->renego_status == MBEDTLS_SSL_RENEGOTIATION_PENDING) { + if ((ret = mbedtls_ssl_resend_hello_request(ssl)) != 0) { + MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_ssl_resend_hello_request", + ret); + return ret; + } + + return MBEDTLS_ERR_SSL_WANT_READ; + } +#endif /* MBEDTLS_SSL_SRV_C && MBEDTLS_SSL_RENEGOTIATION */ + } + + if (ret < 0) { + return ret; + } + + ssl->in_left = ret; + } else +#endif + { + MBEDTLS_SSL_DEBUG_MSG(2, ("in_left: %" MBEDTLS_PRINTF_SIZET + ", nb_want: %" MBEDTLS_PRINTF_SIZET, + ssl->in_left, nb_want)); + + while (ssl->in_left < nb_want) { + len = nb_want - ssl->in_left; + + if (mbedtls_ssl_check_timer(ssl) != 0) { + ret = MBEDTLS_ERR_SSL_TIMEOUT; + } else { + if (ssl->f_recv_timeout != NULL) { + ret = ssl->f_recv_timeout(ssl->p_bio, + ssl->in_hdr + ssl->in_left, len, + ssl->conf->read_timeout); + } else { + ret = ssl->f_recv(ssl->p_bio, + ssl->in_hdr + ssl->in_left, len); + } + } + + MBEDTLS_SSL_DEBUG_MSG(2, ("in_left: %" MBEDTLS_PRINTF_SIZET + ", nb_want: %" MBEDTLS_PRINTF_SIZET, + ssl->in_left, nb_want)); + MBEDTLS_SSL_DEBUG_RET(2, "ssl->f_recv(_timeout)", ret); + + if (ret == 0) { + return MBEDTLS_ERR_SSL_CONN_EOF; + } + + if (ret < 0) { + return ret; + } + + if ((size_t) ret > len) { + MBEDTLS_SSL_DEBUG_MSG(1, + ("f_recv returned %d bytes but only %" MBEDTLS_PRINTF_SIZET + " were requested", + ret, len)); + return MBEDTLS_ERR_SSL_INTERNAL_ERROR; + } + + ssl->in_left += ret; + } + } + + MBEDTLS_SSL_DEBUG_MSG(2, ("<= fetch input")); + + return 0; +} + +/* + * Flush any data not yet written + */ +int mbedtls_ssl_flush_output(mbedtls_ssl_context *ssl) +{ + int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; + unsigned char *buf; + + MBEDTLS_SSL_DEBUG_MSG(2, ("=> flush output")); + + if (ssl->f_send == NULL) { + MBEDTLS_SSL_DEBUG_MSG(1, ("Bad usage of mbedtls_ssl_set_bio() ")); + return MBEDTLS_ERR_SSL_BAD_INPUT_DATA; + } + + /* Avoid incrementing counter if data is flushed */ + if (ssl->out_left == 0) { + MBEDTLS_SSL_DEBUG_MSG(2, ("<= flush output")); + return 0; + } + + while (ssl->out_left > 0) { + MBEDTLS_SSL_DEBUG_MSG(2, ("message length: %" MBEDTLS_PRINTF_SIZET + ", out_left: %" MBEDTLS_PRINTF_SIZET, + mbedtls_ssl_out_hdr_len(ssl) + ssl->out_msglen, ssl->out_left)); + + buf = ssl->out_hdr - ssl->out_left; + ret = ssl->f_send(ssl->p_bio, buf, ssl->out_left); + + MBEDTLS_SSL_DEBUG_RET(2, "ssl->f_send", ret); + + if (ret <= 0) { + return ret; + } + + if ((size_t) ret > ssl->out_left) { + MBEDTLS_SSL_DEBUG_MSG(1, + ("f_send returned %d bytes but only %" MBEDTLS_PRINTF_SIZET + " bytes were sent", + ret, ssl->out_left)); + return MBEDTLS_ERR_SSL_INTERNAL_ERROR; + } + + ssl->out_left -= ret; + } + +#if defined(MBEDTLS_SSL_PROTO_DTLS) + if (ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM) { + ssl->out_hdr = ssl->out_buf; + } else +#endif + { + ssl->out_hdr = ssl->out_buf + 8; + } + mbedtls_ssl_update_out_pointers(ssl, ssl->transform_out); + + MBEDTLS_SSL_DEBUG_MSG(2, ("<= flush output")); + + return 0; +} + +/* + * Functions to handle the DTLS retransmission state machine + */ +#if defined(MBEDTLS_SSL_PROTO_DTLS) +/* + * Append current handshake message to current outgoing flight + */ +MBEDTLS_CHECK_RETURN_CRITICAL +static int ssl_flight_append(mbedtls_ssl_context *ssl) +{ + mbedtls_ssl_flight_item *msg; + MBEDTLS_SSL_DEBUG_MSG(2, ("=> ssl_flight_append")); + MBEDTLS_SSL_DEBUG_BUF(4, "message appended to flight", + ssl->out_msg, ssl->out_msglen); + + /* Allocate space for current message */ + if ((msg = mbedtls_calloc(1, sizeof(mbedtls_ssl_flight_item))) == NULL) { + MBEDTLS_SSL_DEBUG_MSG(1, ("alloc %" MBEDTLS_PRINTF_SIZET " bytes failed", + sizeof(mbedtls_ssl_flight_item))); + return MBEDTLS_ERR_SSL_ALLOC_FAILED; + } + + if ((msg->p = mbedtls_calloc(1, ssl->out_msglen)) == NULL) { + MBEDTLS_SSL_DEBUG_MSG(1, ("alloc %" MBEDTLS_PRINTF_SIZET " bytes failed", + ssl->out_msglen)); + mbedtls_free(msg); + return MBEDTLS_ERR_SSL_ALLOC_FAILED; + } + + /* Copy current handshake message with headers */ + memcpy(msg->p, ssl->out_msg, ssl->out_msglen); + msg->len = ssl->out_msglen; + msg->type = ssl->out_msgtype; + msg->next = NULL; + + /* Append to the current flight */ + if (ssl->handshake->flight == NULL) { + ssl->handshake->flight = msg; + } else { + mbedtls_ssl_flight_item *cur = ssl->handshake->flight; + while (cur->next != NULL) { + cur = cur->next; + } + cur->next = msg; + } + + MBEDTLS_SSL_DEBUG_MSG(2, ("<= ssl_flight_append")); + return 0; +} + +/* + * Free the current flight of handshake messages + */ +void mbedtls_ssl_flight_free(mbedtls_ssl_flight_item *flight) +{ + mbedtls_ssl_flight_item *cur = flight; + mbedtls_ssl_flight_item *next; + + while (cur != NULL) { + next = cur->next; + + mbedtls_free(cur->p); + mbedtls_free(cur); + + cur = next; + } +} + +/* + * Swap transform_out and out_ctr with the alternative ones + */ +MBEDTLS_CHECK_RETURN_CRITICAL +static int ssl_swap_epochs(mbedtls_ssl_context *ssl) +{ + mbedtls_ssl_transform *tmp_transform; + unsigned char tmp_out_ctr[MBEDTLS_SSL_SEQUENCE_NUMBER_LEN]; + + if (ssl->transform_out == ssl->handshake->alt_transform_out) { + MBEDTLS_SSL_DEBUG_MSG(3, ("skip swap epochs")); + return 0; + } + + MBEDTLS_SSL_DEBUG_MSG(3, ("swap epochs")); + + /* Swap transforms */ + tmp_transform = ssl->transform_out; + ssl->transform_out = ssl->handshake->alt_transform_out; + ssl->handshake->alt_transform_out = tmp_transform; + + /* Swap epoch + sequence_number */ + memcpy(tmp_out_ctr, ssl->cur_out_ctr, sizeof(tmp_out_ctr)); + memcpy(ssl->cur_out_ctr, ssl->handshake->alt_out_ctr, + sizeof(ssl->cur_out_ctr)); + memcpy(ssl->handshake->alt_out_ctr, tmp_out_ctr, + sizeof(ssl->handshake->alt_out_ctr)); + + /* Adjust to the newly activated transform */ + mbedtls_ssl_update_out_pointers(ssl, ssl->transform_out); + + return 0; +} + +/* + * Retransmit the current flight of messages. + */ +int mbedtls_ssl_resend(mbedtls_ssl_context *ssl) +{ + int ret = 0; + + MBEDTLS_SSL_DEBUG_MSG(2, ("=> mbedtls_ssl_resend")); + + ret = mbedtls_ssl_flight_transmit(ssl); + + MBEDTLS_SSL_DEBUG_MSG(2, ("<= mbedtls_ssl_resend")); + + return ret; +} + +/* + * Transmit or retransmit the current flight of messages. + * + * Need to remember the current message in case flush_output returns + * WANT_WRITE, causing us to exit this function and come back later. + * This function must be called until state is no longer SENDING. + */ +int mbedtls_ssl_flight_transmit(mbedtls_ssl_context *ssl) +{ + int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; + MBEDTLS_SSL_DEBUG_MSG(2, ("=> mbedtls_ssl_flight_transmit")); + + if (ssl->handshake->retransmit_state != MBEDTLS_SSL_RETRANS_SENDING) { + MBEDTLS_SSL_DEBUG_MSG(2, ("initialise flight transmission")); + + ssl->handshake->cur_msg = ssl->handshake->flight; + ssl->handshake->cur_msg_p = ssl->handshake->flight->p + 12; + ret = ssl_swap_epochs(ssl); + if (ret != 0) { + return ret; + } + + ssl->handshake->retransmit_state = MBEDTLS_SSL_RETRANS_SENDING; + } + + while (ssl->handshake->cur_msg != NULL) { + size_t max_frag_len; + const mbedtls_ssl_flight_item * const cur = ssl->handshake->cur_msg; + + int const is_finished = + (cur->type == MBEDTLS_SSL_MSG_HANDSHAKE && + cur->p[0] == MBEDTLS_SSL_HS_FINISHED); + + int const force_flush = ssl->disable_datagram_packing == 1 ? + SSL_FORCE_FLUSH : SSL_DONT_FORCE_FLUSH; + + /* Swap epochs before sending Finished: we can't do it after + * sending ChangeCipherSpec, in case write returns WANT_READ. + * Must be done before copying, may change out_msg pointer */ + if (is_finished && ssl->handshake->cur_msg_p == (cur->p + 12)) { + MBEDTLS_SSL_DEBUG_MSG(2, ("swap epochs to send finished message")); + ret = ssl_swap_epochs(ssl); + if (ret != 0) { + return ret; + } + } + + ret = ssl_get_remaining_payload_in_datagram(ssl); + if (ret < 0) { + return ret; + } + max_frag_len = (size_t) ret; + + /* CCS is copied as is, while HS messages may need fragmentation */ + if (cur->type == MBEDTLS_SSL_MSG_CHANGE_CIPHER_SPEC) { + if (max_frag_len == 0) { + if ((ret = mbedtls_ssl_flush_output(ssl)) != 0) { + return ret; + } + + continue; + } + + memcpy(ssl->out_msg, cur->p, cur->len); + ssl->out_msglen = cur->len; + ssl->out_msgtype = cur->type; + + /* Update position inside current message */ + ssl->handshake->cur_msg_p += cur->len; + } else { + const unsigned char * const p = ssl->handshake->cur_msg_p; + const size_t hs_len = cur->len - 12; + const size_t frag_off = (size_t) (p - (cur->p + 12)); + const size_t rem_len = hs_len - frag_off; + size_t cur_hs_frag_len, max_hs_frag_len; + + if ((max_frag_len < 12) || (max_frag_len == 12 && hs_len != 0)) { + if (is_finished) { + ret = ssl_swap_epochs(ssl); + if (ret != 0) { + return ret; + } + } + + if ((ret = mbedtls_ssl_flush_output(ssl)) != 0) { + return ret; + } + + continue; + } + max_hs_frag_len = max_frag_len - 12; + + cur_hs_frag_len = rem_len > max_hs_frag_len ? + max_hs_frag_len : rem_len; + + if (frag_off == 0 && cur_hs_frag_len != hs_len) { + MBEDTLS_SSL_DEBUG_MSG(2, ("fragmenting handshake message (%u > %u)", + (unsigned) cur_hs_frag_len, + (unsigned) max_hs_frag_len)); + } + + /* Messages are stored with handshake headers as if not fragmented, + * copy beginning of headers then fill fragmentation fields. + * Handshake headers: type(1) len(3) seq(2) f_off(3) f_len(3) */ + memcpy(ssl->out_msg, cur->p, 6); + + ssl->out_msg[6] = MBEDTLS_BYTE_2(frag_off); + ssl->out_msg[7] = MBEDTLS_BYTE_1(frag_off); + ssl->out_msg[8] = MBEDTLS_BYTE_0(frag_off); + + ssl->out_msg[9] = MBEDTLS_BYTE_2(cur_hs_frag_len); + ssl->out_msg[10] = MBEDTLS_BYTE_1(cur_hs_frag_len); + ssl->out_msg[11] = MBEDTLS_BYTE_0(cur_hs_frag_len); + + MBEDTLS_SSL_DEBUG_BUF(3, "handshake header", ssl->out_msg, 12); + + /* Copy the handshake message content and set records fields */ + memcpy(ssl->out_msg + 12, p, cur_hs_frag_len); + ssl->out_msglen = cur_hs_frag_len + 12; + ssl->out_msgtype = cur->type; + + /* Update position inside current message */ + ssl->handshake->cur_msg_p += cur_hs_frag_len; + } + + /* If done with the current message move to the next one if any */ + if (ssl->handshake->cur_msg_p >= cur->p + cur->len) { + if (cur->next != NULL) { + ssl->handshake->cur_msg = cur->next; + ssl->handshake->cur_msg_p = cur->next->p + 12; + } else { + ssl->handshake->cur_msg = NULL; + ssl->handshake->cur_msg_p = NULL; + } + } + + /* Actually send the message out */ + if ((ret = mbedtls_ssl_write_record(ssl, force_flush)) != 0) { + MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_ssl_write_record", ret); + return ret; + } + } + + if ((ret = mbedtls_ssl_flush_output(ssl)) != 0) { + return ret; + } + + /* Update state and set timer */ + if (mbedtls_ssl_is_handshake_over(ssl) == 1) { + ssl->handshake->retransmit_state = MBEDTLS_SSL_RETRANS_FINISHED; + } else { + ssl->handshake->retransmit_state = MBEDTLS_SSL_RETRANS_WAITING; + mbedtls_ssl_set_timer(ssl, ssl->handshake->retransmit_timeout); + } + + MBEDTLS_SSL_DEBUG_MSG(2, ("<= mbedtls_ssl_flight_transmit")); + + return 0; +} + +/* + * To be called when the last message of an incoming flight is received. + */ +void mbedtls_ssl_recv_flight_completed(mbedtls_ssl_context *ssl) +{ + /* We won't need to resend that one any more */ + mbedtls_ssl_flight_free(ssl->handshake->flight); + ssl->handshake->flight = NULL; + ssl->handshake->cur_msg = NULL; + + /* The next incoming flight will start with this msg_seq */ + ssl->handshake->in_flight_start_seq = ssl->handshake->in_msg_seq; + + /* We don't want to remember CCS's across flight boundaries. */ + ssl->handshake->buffering.seen_ccs = 0; + + /* Clear future message buffering structure. */ + mbedtls_ssl_buffering_free(ssl); + + /* Cancel timer */ + mbedtls_ssl_set_timer(ssl, 0); + + if (ssl->in_msgtype == MBEDTLS_SSL_MSG_HANDSHAKE && + ssl->in_msg[0] == MBEDTLS_SSL_HS_FINISHED) { + ssl->handshake->retransmit_state = MBEDTLS_SSL_RETRANS_FINISHED; + } else { + ssl->handshake->retransmit_state = MBEDTLS_SSL_RETRANS_PREPARING; + } +} + +/* + * To be called when the last message of an outgoing flight is send. + */ +void mbedtls_ssl_send_flight_completed(mbedtls_ssl_context *ssl) +{ + ssl_reset_retransmit_timeout(ssl); + mbedtls_ssl_set_timer(ssl, ssl->handshake->retransmit_timeout); + + if (ssl->in_msgtype == MBEDTLS_SSL_MSG_HANDSHAKE && + ssl->in_msg[0] == MBEDTLS_SSL_HS_FINISHED) { + ssl->handshake->retransmit_state = MBEDTLS_SSL_RETRANS_FINISHED; + } else { + ssl->handshake->retransmit_state = MBEDTLS_SSL_RETRANS_WAITING; + } +} +#endif /* MBEDTLS_SSL_PROTO_DTLS */ + +/* + * Handshake layer functions + */ +int mbedtls_ssl_start_handshake_msg(mbedtls_ssl_context *ssl, unsigned char hs_type, + unsigned char **buf, size_t *buf_len) +{ + /* + * Reserve 4 bytes for handshake header. ( Section 4,RFC 8446 ) + * ... + * HandshakeType msg_type; + * uint24 length; + * ... + */ + *buf = ssl->out_msg + 4; + *buf_len = MBEDTLS_SSL_OUT_CONTENT_LEN - 4; + + ssl->out_msgtype = MBEDTLS_SSL_MSG_HANDSHAKE; + ssl->out_msg[0] = hs_type; + + return 0; +} + +/* + * Write (DTLS: or queue) current handshake (including CCS) message. + * + * - fill in handshake headers + * - update handshake checksum + * - DTLS: save message for resending + * - then pass to the record layer + * + * DTLS: except for HelloRequest, messages are only queued, and will only be + * actually sent when calling flight_transmit() or resend(). + * + * Inputs: + * - ssl->out_msglen: 4 + actual handshake message len + * (4 is the size of handshake headers for TLS) + * - ssl->out_msg[0]: the handshake type (ClientHello, ServerHello, etc) + * - ssl->out_msg + 4: the handshake message body + * + * Outputs, ie state before passing to flight_append() or write_record(): + * - ssl->out_msglen: the length of the record contents + * (including handshake headers but excluding record headers) + * - ssl->out_msg: the record contents (handshake headers + content) + */ +int mbedtls_ssl_write_handshake_msg_ext(mbedtls_ssl_context *ssl, + int update_checksum, + int force_flush) +{ + int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; + const size_t hs_len = ssl->out_msglen - 4; + const unsigned char hs_type = ssl->out_msg[0]; + + MBEDTLS_SSL_DEBUG_MSG(2, ("=> write handshake message")); + + /* + * Sanity checks + */ + if (ssl->out_msgtype != MBEDTLS_SSL_MSG_HANDSHAKE && + ssl->out_msgtype != MBEDTLS_SSL_MSG_CHANGE_CIPHER_SPEC) { + MBEDTLS_SSL_DEBUG_MSG(1, ("should never happen")); + return MBEDTLS_ERR_SSL_INTERNAL_ERROR; + } + + /* Whenever we send anything different from a + * HelloRequest we should be in a handshake - double check. */ + if (!(ssl->out_msgtype == MBEDTLS_SSL_MSG_HANDSHAKE && + hs_type == MBEDTLS_SSL_HS_HELLO_REQUEST) && + ssl->handshake == NULL) { + MBEDTLS_SSL_DEBUG_MSG(1, ("should never happen")); + return MBEDTLS_ERR_SSL_INTERNAL_ERROR; + } + +#if defined(MBEDTLS_SSL_PROTO_DTLS) + if (ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM && + ssl->handshake != NULL && + ssl->handshake->retransmit_state == MBEDTLS_SSL_RETRANS_SENDING) { + MBEDTLS_SSL_DEBUG_MSG(1, ("should never happen")); + return MBEDTLS_ERR_SSL_INTERNAL_ERROR; + } +#endif + + /* Double-check that we did not exceed the bounds + * of the outgoing record buffer. + * This should never fail as the various message + * writing functions must obey the bounds of the + * outgoing record buffer, but better be safe. + * + * Note: We deliberately do not check for the MTU or MFL here. + */ + if (ssl->out_msglen > MBEDTLS_SSL_OUT_CONTENT_LEN) { + MBEDTLS_SSL_DEBUG_MSG(1, ("Record too large: " + "size %" MBEDTLS_PRINTF_SIZET + ", maximum %" MBEDTLS_PRINTF_SIZET, + ssl->out_msglen, + (size_t) MBEDTLS_SSL_OUT_CONTENT_LEN)); + return MBEDTLS_ERR_SSL_INTERNAL_ERROR; + } + + /* + * Fill handshake headers + */ + if (ssl->out_msgtype == MBEDTLS_SSL_MSG_HANDSHAKE) { + ssl->out_msg[1] = MBEDTLS_BYTE_2(hs_len); + ssl->out_msg[2] = MBEDTLS_BYTE_1(hs_len); + ssl->out_msg[3] = MBEDTLS_BYTE_0(hs_len); + + /* + * DTLS has additional fields in the Handshake layer, + * between the length field and the actual payload: + * uint16 message_seq; + * uint24 fragment_offset; + * uint24 fragment_length; + */ +#if defined(MBEDTLS_SSL_PROTO_DTLS) + if (ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM) { + /* Make room for the additional DTLS fields */ + if (MBEDTLS_SSL_OUT_CONTENT_LEN - ssl->out_msglen < 8) { + MBEDTLS_SSL_DEBUG_MSG(1, ("DTLS handshake message too large: " + "size %" MBEDTLS_PRINTF_SIZET ", maximum %" + MBEDTLS_PRINTF_SIZET, + hs_len, + (size_t) (MBEDTLS_SSL_OUT_CONTENT_LEN - 12))); + return MBEDTLS_ERR_SSL_BAD_INPUT_DATA; + } + + memmove(ssl->out_msg + 12, ssl->out_msg + 4, hs_len); + ssl->out_msglen += 8; + + /* Write message_seq and update it, except for HelloRequest */ + if (hs_type != MBEDTLS_SSL_HS_HELLO_REQUEST) { + MBEDTLS_PUT_UINT16_BE(ssl->handshake->out_msg_seq, ssl->out_msg, 4); + ++(ssl->handshake->out_msg_seq); + } else { + ssl->out_msg[4] = 0; + ssl->out_msg[5] = 0; + } + + /* Handshake hashes are computed without fragmentation, + * so set frag_offset = 0 and frag_len = hs_len for now */ + memset(ssl->out_msg + 6, 0x00, 3); + memcpy(ssl->out_msg + 9, ssl->out_msg + 1, 3); + } +#endif /* MBEDTLS_SSL_PROTO_DTLS */ + + /* Update running hashes of handshake messages seen */ + if (hs_type != MBEDTLS_SSL_HS_HELLO_REQUEST && update_checksum != 0) { + ret = ssl->handshake->update_checksum(ssl, ssl->out_msg, + ssl->out_msglen); + if (ret != 0) { + MBEDTLS_SSL_DEBUG_RET(1, "update_checksum", ret); + return ret; + } + } + } + + /* Either send now, or just save to be sent (and resent) later */ +#if defined(MBEDTLS_SSL_PROTO_DTLS) + if (ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM && + !(ssl->out_msgtype == MBEDTLS_SSL_MSG_HANDSHAKE && + hs_type == MBEDTLS_SSL_HS_HELLO_REQUEST)) { + if ((ret = ssl_flight_append(ssl)) != 0) { + MBEDTLS_SSL_DEBUG_RET(1, "ssl_flight_append", ret); + return ret; + } + } else +#endif + { + if ((ret = mbedtls_ssl_write_record(ssl, force_flush)) != 0) { + MBEDTLS_SSL_DEBUG_RET(1, "ssl_write_record", ret); + return ret; + } + } + + MBEDTLS_SSL_DEBUG_MSG(2, ("<= write handshake message")); + + return 0; +} + +int mbedtls_ssl_finish_handshake_msg(mbedtls_ssl_context *ssl, + size_t buf_len, size_t msg_len) +{ + int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; + size_t msg_with_header_len; + ((void) buf_len); + + /* Add reserved 4 bytes for handshake header */ + msg_with_header_len = msg_len + 4; + ssl->out_msglen = msg_with_header_len; + MBEDTLS_SSL_PROC_CHK(mbedtls_ssl_write_handshake_msg_ext(ssl, 0, 0)); + +cleanup: + return ret; +} + +/* + * Record layer functions + */ + +/* + * Write current record. + * + * Uses: + * - ssl->out_msgtype: type of the message (AppData, Handshake, Alert, CCS) + * - ssl->out_msglen: length of the record content (excl headers) + * - ssl->out_msg: record content + */ +int mbedtls_ssl_write_record(mbedtls_ssl_context *ssl, int force_flush) +{ + int ret, done = 0; + size_t len = ssl->out_msglen; + int flush = force_flush; + + MBEDTLS_SSL_DEBUG_MSG(2, ("=> write record")); + + if (!done) { + unsigned i; + size_t protected_record_size; +#if defined(MBEDTLS_SSL_VARIABLE_BUFFER_LENGTH) + size_t out_buf_len = ssl->out_buf_len; +#else + size_t out_buf_len = MBEDTLS_SSL_OUT_BUFFER_LEN; +#endif + /* Skip writing the record content type to after the encryption, + * as it may change when using the CID extension. */ + mbedtls_ssl_protocol_version tls_ver = ssl->tls_version; +#if defined(MBEDTLS_SSL_PROTO_TLS1_3) + /* TLS 1.3 still uses the TLS 1.2 version identifier + * for backwards compatibility. */ + if (tls_ver == MBEDTLS_SSL_VERSION_TLS1_3) { + tls_ver = MBEDTLS_SSL_VERSION_TLS1_2; + } +#endif /* MBEDTLS_SSL_PROTO_TLS1_3 */ + mbedtls_ssl_write_version(ssl->out_hdr + 1, ssl->conf->transport, + tls_ver); + + memcpy(ssl->out_ctr, ssl->cur_out_ctr, MBEDTLS_SSL_SEQUENCE_NUMBER_LEN); + MBEDTLS_PUT_UINT16_BE(len, ssl->out_len, 0); + + if (ssl->transform_out != NULL) { + mbedtls_record rec; + + rec.buf = ssl->out_iv; + rec.buf_len = out_buf_len - (size_t) (ssl->out_iv - ssl->out_buf); + rec.data_len = ssl->out_msglen; + rec.data_offset = (size_t) (ssl->out_msg - rec.buf); + + memcpy(&rec.ctr[0], ssl->out_ctr, sizeof(rec.ctr)); + mbedtls_ssl_write_version(rec.ver, ssl->conf->transport, tls_ver); + rec.type = ssl->out_msgtype; + +#if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID) + /* The CID is set by mbedtls_ssl_encrypt_buf(). */ + rec.cid_len = 0; +#endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID */ + + if ((ret = mbedtls_ssl_encrypt_buf(ssl, ssl->transform_out, &rec, + ssl->conf->f_rng, ssl->conf->p_rng)) != 0) { + MBEDTLS_SSL_DEBUG_RET(1, "ssl_encrypt_buf", ret); + return ret; + } + + if (rec.data_offset != 0) { + MBEDTLS_SSL_DEBUG_MSG(1, ("should never happen")); + return MBEDTLS_ERR_SSL_INTERNAL_ERROR; + } + + /* Update the record content type and CID. */ + ssl->out_msgtype = rec.type; +#if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID) + memcpy(ssl->out_cid, rec.cid, rec.cid_len); +#endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID */ + ssl->out_msglen = len = rec.data_len; + MBEDTLS_PUT_UINT16_BE(rec.data_len, ssl->out_len, 0); + } + + protected_record_size = len + mbedtls_ssl_out_hdr_len(ssl); + +#if defined(MBEDTLS_SSL_PROTO_DTLS) + /* In case of DTLS, double-check that we don't exceed + * the remaining space in the datagram. */ + if (ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM) { + ret = ssl_get_remaining_space_in_datagram(ssl); + if (ret < 0) { + return ret; + } + + if (protected_record_size > (size_t) ret) { + /* Should never happen */ + return MBEDTLS_ERR_SSL_INTERNAL_ERROR; + } + } +#endif /* MBEDTLS_SSL_PROTO_DTLS */ + + /* Now write the potentially updated record content type. */ + ssl->out_hdr[0] = (unsigned char) ssl->out_msgtype; + + MBEDTLS_SSL_DEBUG_MSG(3, ("output record: msgtype = %u, " + "version = [%u:%u], msglen = %" MBEDTLS_PRINTF_SIZET, + ssl->out_hdr[0], ssl->out_hdr[1], + ssl->out_hdr[2], len)); + + MBEDTLS_SSL_DEBUG_BUF(4, "output record sent to network", + ssl->out_hdr, protected_record_size); + + ssl->out_left += protected_record_size; + ssl->out_hdr += protected_record_size; + mbedtls_ssl_update_out_pointers(ssl, ssl->transform_out); + + for (i = 8; i > mbedtls_ssl_ep_len(ssl); i--) { + if (++ssl->cur_out_ctr[i - 1] != 0) { + break; + } + } + + /* The loop goes to its end if the counter is wrapping */ + if (i == mbedtls_ssl_ep_len(ssl)) { + MBEDTLS_SSL_DEBUG_MSG(1, ("outgoing message counter would wrap")); + return MBEDTLS_ERR_SSL_COUNTER_WRAPPING; + } + } + +#if defined(MBEDTLS_SSL_PROTO_DTLS) + if (ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM && + flush == SSL_DONT_FORCE_FLUSH) { + size_t remaining; + ret = ssl_get_remaining_payload_in_datagram(ssl); + if (ret < 0) { + MBEDTLS_SSL_DEBUG_RET(1, "ssl_get_remaining_payload_in_datagram", + ret); + return ret; + } + + remaining = (size_t) ret; + if (remaining == 0) { + flush = SSL_FORCE_FLUSH; + } else { + MBEDTLS_SSL_DEBUG_MSG(2, + ("Still %u bytes available in current datagram", + (unsigned) remaining)); + } + } +#endif /* MBEDTLS_SSL_PROTO_DTLS */ + + if ((flush == SSL_FORCE_FLUSH) && + (ret = mbedtls_ssl_flush_output(ssl)) != 0) { + MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_ssl_flush_output", ret); + return ret; + } + + MBEDTLS_SSL_DEBUG_MSG(2, ("<= write record")); + + return 0; +} + +#if defined(MBEDTLS_SSL_PROTO_DTLS) + +MBEDTLS_CHECK_RETURN_CRITICAL +static int ssl_hs_is_proper_fragment(mbedtls_ssl_context *ssl) +{ + if (ssl->in_msglen < ssl->in_hslen || + memcmp(ssl->in_msg + 6, "\0\0\0", 3) != 0 || + memcmp(ssl->in_msg + 9, ssl->in_msg + 1, 3) != 0) { + return 1; + } + return 0; +} + +static uint32_t ssl_get_hs_frag_len(mbedtls_ssl_context const *ssl) +{ + return MBEDTLS_GET_UINT24_BE(ssl->in_msg, 9); +} + +static uint32_t ssl_get_hs_frag_off(mbedtls_ssl_context const *ssl) +{ + return MBEDTLS_GET_UINT24_BE(ssl->in_msg, 6); +} + +MBEDTLS_CHECK_RETURN_CRITICAL +static int ssl_check_hs_header(mbedtls_ssl_context const *ssl) +{ + uint32_t msg_len, frag_off, frag_len; + + msg_len = ssl_get_hs_total_len(ssl); + frag_off = ssl_get_hs_frag_off(ssl); + frag_len = ssl_get_hs_frag_len(ssl); + + if (frag_off > msg_len) { + return -1; + } + + if (frag_len > msg_len - frag_off) { + return -1; + } + + if (frag_len + 12 > ssl->in_msglen) { + return -1; + } + + return 0; +} + +/* + * Mark bits in bitmask (used for DTLS HS reassembly) + */ +static void ssl_bitmask_set(unsigned char *mask, size_t offset, size_t len) +{ + unsigned int start_bits, end_bits; + + start_bits = 8 - (offset % 8); + if (start_bits != 8) { + size_t first_byte_idx = offset / 8; + + /* Special case */ + if (len <= start_bits) { + for (; len != 0; len--) { + mask[first_byte_idx] |= 1 << (start_bits - len); + } + + /* Avoid potential issues with offset or len becoming invalid */ + return; + } + + offset += start_bits; /* Now offset % 8 == 0 */ + len -= start_bits; + + for (; start_bits != 0; start_bits--) { + mask[first_byte_idx] |= 1 << (start_bits - 1); + } + } + + end_bits = len % 8; + if (end_bits != 0) { + size_t last_byte_idx = (offset + len) / 8; + + len -= end_bits; /* Now len % 8 == 0 */ + + for (; end_bits != 0; end_bits--) { + mask[last_byte_idx] |= 1 << (8 - end_bits); + } + } + + memset(mask + offset / 8, 0xFF, len / 8); +} + +/* + * Check that bitmask is full + */ +MBEDTLS_CHECK_RETURN_CRITICAL +static int ssl_bitmask_check(unsigned char *mask, size_t len) +{ + size_t i; + + for (i = 0; i < len / 8; i++) { + if (mask[i] != 0xFF) { + return -1; + } + } + + for (i = 0; i < len % 8; i++) { + if ((mask[len / 8] & (1 << (7 - i))) == 0) { + return -1; + } + } + + return 0; +} + +/* msg_len does not include the handshake header */ +static size_t ssl_get_reassembly_buffer_size(size_t msg_len, + unsigned add_bitmap) +{ + size_t alloc_len; + + alloc_len = 12; /* Handshake header */ + alloc_len += msg_len; /* Content buffer */ + + if (add_bitmap) { + alloc_len += msg_len / 8 + (msg_len % 8 != 0); /* Bitmap */ + + } + return alloc_len; +} + +#endif /* MBEDTLS_SSL_PROTO_DTLS */ + +static uint32_t ssl_get_hs_total_len(mbedtls_ssl_context const *ssl) +{ + return MBEDTLS_GET_UINT24_BE(ssl->in_msg, 1); +} + +int mbedtls_ssl_prepare_handshake_record(mbedtls_ssl_context *ssl) +{ + if (ssl->in_msglen < mbedtls_ssl_hs_hdr_len(ssl)) { + MBEDTLS_SSL_DEBUG_MSG(1, ("handshake message too short: %" MBEDTLS_PRINTF_SIZET, + ssl->in_msglen)); + return MBEDTLS_ERR_SSL_INVALID_RECORD; + } + + ssl->in_hslen = mbedtls_ssl_hs_hdr_len(ssl) + ssl_get_hs_total_len(ssl); + + MBEDTLS_SSL_DEBUG_MSG(3, ("handshake message: msglen =" + " %" MBEDTLS_PRINTF_SIZET ", type = %u, hslen = %" + MBEDTLS_PRINTF_SIZET, + ssl->in_msglen, ssl->in_msg[0], ssl->in_hslen)); + +#if defined(MBEDTLS_SSL_PROTO_DTLS) + if (ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM) { + int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; + unsigned int recv_msg_seq = MBEDTLS_GET_UINT16_BE(ssl->in_msg, 4); + + if (ssl_check_hs_header(ssl) != 0) { + MBEDTLS_SSL_DEBUG_MSG(1, ("invalid handshake header")); + return MBEDTLS_ERR_SSL_INVALID_RECORD; + } + + if (ssl->handshake != NULL && + ((mbedtls_ssl_is_handshake_over(ssl) == 0 && + recv_msg_seq != ssl->handshake->in_msg_seq) || + (mbedtls_ssl_is_handshake_over(ssl) == 1 && + ssl->in_msg[0] != MBEDTLS_SSL_HS_CLIENT_HELLO))) { + if (recv_msg_seq > ssl->handshake->in_msg_seq) { + MBEDTLS_SSL_DEBUG_MSG(2, + ( + "received future handshake message of sequence number %u (next %u)", + recv_msg_seq, + ssl->handshake->in_msg_seq)); + return MBEDTLS_ERR_SSL_EARLY_MESSAGE; + } + + /* Retransmit only on last message from previous flight, to avoid + * too many retransmissions. + * Besides, No sane server ever retransmits HelloVerifyRequest */ + if (recv_msg_seq == ssl->handshake->in_flight_start_seq - 1 && + ssl->in_msg[0] != MBEDTLS_SSL_HS_HELLO_VERIFY_REQUEST) { + MBEDTLS_SSL_DEBUG_MSG(2, ("received message from last flight, " + "message_seq = %u, start_of_flight = %u", + recv_msg_seq, + ssl->handshake->in_flight_start_seq)); + + if ((ret = mbedtls_ssl_resend(ssl)) != 0) { + MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_ssl_resend", ret); + return ret; + } + } else { + MBEDTLS_SSL_DEBUG_MSG(2, ("dropping out-of-sequence message: " + "message_seq = %u, expected = %u", + recv_msg_seq, + ssl->handshake->in_msg_seq)); + } + + return MBEDTLS_ERR_SSL_CONTINUE_PROCESSING; + } + /* Wait until message completion to increment in_msg_seq */ + + /* Message reassembly is handled alongside buffering of future + * messages; the commonality is that both handshake fragments and + * future messages cannot be forwarded immediately to the + * handshake logic layer. */ + if (ssl_hs_is_proper_fragment(ssl) == 1) { + MBEDTLS_SSL_DEBUG_MSG(2, ("found fragmented DTLS handshake message")); + return MBEDTLS_ERR_SSL_EARLY_MESSAGE; + } + } else +#endif /* MBEDTLS_SSL_PROTO_DTLS */ + /* With TLS we don't handle fragmentation (for now) */ + if (ssl->in_msglen < ssl->in_hslen) { + MBEDTLS_SSL_DEBUG_MSG(1, ("TLS handshake fragmentation not supported")); + return MBEDTLS_ERR_SSL_FEATURE_UNAVAILABLE; + } + + return 0; +} + +int mbedtls_ssl_update_handshake_status(mbedtls_ssl_context *ssl) +{ + int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; + mbedtls_ssl_handshake_params * const hs = ssl->handshake; + + if (mbedtls_ssl_is_handshake_over(ssl) == 0 && hs != NULL) { + ret = ssl->handshake->update_checksum(ssl, ssl->in_msg, ssl->in_hslen); + if (ret != 0) { + MBEDTLS_SSL_DEBUG_RET(1, "update_checksum", ret); + return ret; + } + } + + /* Handshake message is complete, increment counter */ +#if defined(MBEDTLS_SSL_PROTO_DTLS) + if (ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM && + ssl->handshake != NULL) { + unsigned offset; + mbedtls_ssl_hs_buffer *hs_buf; + + /* Increment handshake sequence number */ + hs->in_msg_seq++; + + /* + * Clear up handshake buffering and reassembly structure. + */ + + /* Free first entry */ + ssl_buffering_free_slot(ssl, 0); + + /* Shift all other entries */ + for (offset = 0, hs_buf = &hs->buffering.hs[0]; + offset + 1 < MBEDTLS_SSL_MAX_BUFFERED_HS; + offset++, hs_buf++) { + *hs_buf = *(hs_buf + 1); + } + + /* Create a fresh last entry */ + memset(hs_buf, 0, sizeof(mbedtls_ssl_hs_buffer)); + } +#endif + return 0; +} + +/* + * DTLS anti-replay: RFC 6347 4.1.2.6 + * + * in_window is a field of bits numbered from 0 (lsb) to 63 (msb). + * Bit n is set iff record number in_window_top - n has been seen. + * + * Usually, in_window_top is the last record number seen and the lsb of + * in_window is set. The only exception is the initial state (record number 0 + * not seen yet). + */ +#if defined(MBEDTLS_SSL_DTLS_ANTI_REPLAY) +void mbedtls_ssl_dtls_replay_reset(mbedtls_ssl_context *ssl) +{ + ssl->in_window_top = 0; + ssl->in_window = 0; +} + +static inline uint64_t ssl_load_six_bytes(unsigned char *buf) +{ + return ((uint64_t) buf[0] << 40) | + ((uint64_t) buf[1] << 32) | + ((uint64_t) buf[2] << 24) | + ((uint64_t) buf[3] << 16) | + ((uint64_t) buf[4] << 8) | + ((uint64_t) buf[5]); +} + +MBEDTLS_CHECK_RETURN_CRITICAL +static int mbedtls_ssl_dtls_record_replay_check(mbedtls_ssl_context *ssl, uint8_t *record_in_ctr) +{ + int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; + unsigned char *original_in_ctr; + + // save original in_ctr + original_in_ctr = ssl->in_ctr; + + // use counter from record + ssl->in_ctr = record_in_ctr; + + ret = mbedtls_ssl_dtls_replay_check((mbedtls_ssl_context const *) ssl); + + // restore the counter + ssl->in_ctr = original_in_ctr; + + return ret; +} + +/* + * Return 0 if sequence number is acceptable, -1 otherwise + */ +int mbedtls_ssl_dtls_replay_check(mbedtls_ssl_context const *ssl) +{ + uint64_t rec_seqnum = ssl_load_six_bytes(ssl->in_ctr + 2); + uint64_t bit; + + if (ssl->conf->anti_replay == MBEDTLS_SSL_ANTI_REPLAY_DISABLED) { + return 0; + } + + if (rec_seqnum > ssl->in_window_top) { + return 0; + } + + bit = ssl->in_window_top - rec_seqnum; + + if (bit >= 64) { + return -1; + } + + if ((ssl->in_window & ((uint64_t) 1 << bit)) != 0) { + return -1; + } + + return 0; +} + +/* + * Update replay window on new validated record + */ +void mbedtls_ssl_dtls_replay_update(mbedtls_ssl_context *ssl) +{ + uint64_t rec_seqnum = ssl_load_six_bytes(ssl->in_ctr + 2); + + if (ssl->conf->anti_replay == MBEDTLS_SSL_ANTI_REPLAY_DISABLED) { + return; + } + + if (rec_seqnum > ssl->in_window_top) { + /* Update window_top and the contents of the window */ + uint64_t shift = rec_seqnum - ssl->in_window_top; + + if (shift >= 64) { + ssl->in_window = 1; + } else { + ssl->in_window <<= shift; + ssl->in_window |= 1; + } + + ssl->in_window_top = rec_seqnum; + } else { + /* Mark that number as seen in the current window */ + uint64_t bit = ssl->in_window_top - rec_seqnum; + + if (bit < 64) { /* Always true, but be extra sure */ + ssl->in_window |= (uint64_t) 1 << bit; + } + } +} +#endif /* MBEDTLS_SSL_DTLS_ANTI_REPLAY */ + +#if defined(MBEDTLS_SSL_DTLS_CLIENT_PORT_REUSE) && defined(MBEDTLS_SSL_SRV_C) +/* + * Check if a datagram looks like a ClientHello with a valid cookie, + * and if it doesn't, generate a HelloVerifyRequest message. + * Both input and output include full DTLS headers. + * + * - if cookie is valid, return 0 + * - if ClientHello looks superficially valid but cookie is not, + * fill obuf and set olen, then + * return MBEDTLS_ERR_SSL_HELLO_VERIFY_REQUIRED + * - otherwise return a specific error code + */ +MBEDTLS_CHECK_RETURN_CRITICAL +MBEDTLS_STATIC_TESTABLE +int mbedtls_ssl_check_dtls_clihlo_cookie( + mbedtls_ssl_context *ssl, + const unsigned char *cli_id, size_t cli_id_len, + const unsigned char *in, size_t in_len, + unsigned char *obuf, size_t buf_len, size_t *olen) +{ + size_t sid_len, cookie_len, epoch, fragment_offset; + unsigned char *p; + + /* + * Structure of ClientHello with record and handshake headers, + * and expected values. We don't need to check a lot, more checks will be + * done when actually parsing the ClientHello - skipping those checks + * avoids code duplication and does not make cookie forging any easier. + * + * 0-0 ContentType type; copied, must be handshake + * 1-2 ProtocolVersion version; copied + * 3-4 uint16 epoch; copied, must be 0 + * 5-10 uint48 sequence_number; copied + * 11-12 uint16 length; (ignored) + * + * 13-13 HandshakeType msg_type; (ignored) + * 14-16 uint24 length; (ignored) + * 17-18 uint16 message_seq; copied + * 19-21 uint24 fragment_offset; copied, must be 0 + * 22-24 uint24 fragment_length; (ignored) + * + * 25-26 ProtocolVersion client_version; (ignored) + * 27-58 Random random; (ignored) + * 59-xx SessionID session_id; 1 byte len + sid_len content + * 60+ opaque cookie<0..2^8-1>; 1 byte len + content + * ... + * + * Minimum length is 61 bytes. + */ + MBEDTLS_SSL_DEBUG_MSG(4, ("check cookie: in_len=%u", + (unsigned) in_len)); + MBEDTLS_SSL_DEBUG_BUF(4, "cli_id", cli_id, cli_id_len); + if (in_len < 61) { + MBEDTLS_SSL_DEBUG_MSG(4, ("check cookie: record too short")); + return MBEDTLS_ERR_SSL_DECODE_ERROR; + } + + epoch = MBEDTLS_GET_UINT16_BE(in, 3); + fragment_offset = MBEDTLS_GET_UINT24_BE(in, 19); + + if (in[0] != MBEDTLS_SSL_MSG_HANDSHAKE || epoch != 0 || + fragment_offset != 0) { + MBEDTLS_SSL_DEBUG_MSG(4, ("check cookie: not a good ClientHello")); + MBEDTLS_SSL_DEBUG_MSG(4, (" type=%u epoch=%u fragment_offset=%u", + in[0], (unsigned) epoch, + (unsigned) fragment_offset)); + return MBEDTLS_ERR_SSL_DECODE_ERROR; + } + + sid_len = in[59]; + if (59 + 1 + sid_len + 1 > in_len) { + MBEDTLS_SSL_DEBUG_MSG(4, ("check cookie: sid_len=%u > %u", + (unsigned) sid_len, + (unsigned) in_len - 61)); + return MBEDTLS_ERR_SSL_DECODE_ERROR; + } + MBEDTLS_SSL_DEBUG_BUF(4, "sid received from network", + in + 60, sid_len); + + cookie_len = in[60 + sid_len]; + if (59 + 1 + sid_len + 1 + cookie_len > in_len) { + MBEDTLS_SSL_DEBUG_MSG(4, ("check cookie: cookie_len=%u > %u", + (unsigned) cookie_len, + (unsigned) (in_len - sid_len - 61))); + return MBEDTLS_ERR_SSL_DECODE_ERROR; + } + + MBEDTLS_SSL_DEBUG_BUF(4, "cookie received from network", + in + sid_len + 61, cookie_len); + if (ssl->conf->f_cookie_check(ssl->conf->p_cookie, + in + sid_len + 61, cookie_len, + cli_id, cli_id_len) == 0) { + MBEDTLS_SSL_DEBUG_MSG(4, ("check cookie: valid")); + return 0; + } + + /* + * If we get here, we've got an invalid cookie, let's prepare HVR. + * + * 0-0 ContentType type; copied + * 1-2 ProtocolVersion version; copied + * 3-4 uint16 epoch; copied + * 5-10 uint48 sequence_number; copied + * 11-12 uint16 length; olen - 13 + * + * 13-13 HandshakeType msg_type; hello_verify_request + * 14-16 uint24 length; olen - 25 + * 17-18 uint16 message_seq; copied + * 19-21 uint24 fragment_offset; copied + * 22-24 uint24 fragment_length; olen - 25 + * + * 25-26 ProtocolVersion server_version; 0xfe 0xff + * 27-27 opaque cookie<0..2^8-1>; cookie_len = olen - 27, cookie + * + * Minimum length is 28. + */ + if (buf_len < 28) { + return MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL; + } + + /* Copy most fields and adapt others */ + memcpy(obuf, in, 25); + obuf[13] = MBEDTLS_SSL_HS_HELLO_VERIFY_REQUEST; + obuf[25] = 0xfe; + obuf[26] = 0xff; + + /* Generate and write actual cookie */ + p = obuf + 28; + if (ssl->conf->f_cookie_write(ssl->conf->p_cookie, + &p, obuf + buf_len, + cli_id, cli_id_len) != 0) { + return MBEDTLS_ERR_SSL_INTERNAL_ERROR; + } + + *olen = (size_t) (p - obuf); + + /* Go back and fill length fields */ + obuf[27] = (unsigned char) (*olen - 28); + + obuf[14] = obuf[22] = MBEDTLS_BYTE_2(*olen - 25); + obuf[15] = obuf[23] = MBEDTLS_BYTE_1(*olen - 25); + obuf[16] = obuf[24] = MBEDTLS_BYTE_0(*olen - 25); + + MBEDTLS_PUT_UINT16_BE(*olen - 13, obuf, 11); + + return MBEDTLS_ERR_SSL_HELLO_VERIFY_REQUIRED; +} + +/* + * Handle possible client reconnect with the same UDP quadruplet + * (RFC 6347 Section 4.2.8). + * + * Called by ssl_parse_record_header() in case we receive an epoch 0 record + * that looks like a ClientHello. + * + * - if the input looks like a ClientHello without cookies, + * send back HelloVerifyRequest, then return 0 + * - if the input looks like a ClientHello with a valid cookie, + * reset the session of the current context, and + * return MBEDTLS_ERR_SSL_CLIENT_RECONNECT + * - if anything goes wrong, return a specific error code + * + * This function is called (through ssl_check_client_reconnect()) when an + * unexpected record is found in ssl_get_next_record(), which will discard the + * record if we return 0, and bubble up the return value otherwise (this + * includes the case of MBEDTLS_ERR_SSL_CLIENT_RECONNECT and of unexpected + * errors, and is the right thing to do in both cases). + */ +MBEDTLS_CHECK_RETURN_CRITICAL +static int ssl_handle_possible_reconnect(mbedtls_ssl_context *ssl) +{ + int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; + size_t len = 0; + + if (ssl->conf->f_cookie_write == NULL || + ssl->conf->f_cookie_check == NULL) { + /* If we can't use cookies to verify reachability of the peer, + * drop the record. */ + MBEDTLS_SSL_DEBUG_MSG(1, ("no cookie callbacks, " + "can't check reconnect validity")); + return 0; + } + + ret = mbedtls_ssl_check_dtls_clihlo_cookie( + ssl, + ssl->cli_id, ssl->cli_id_len, + ssl->in_buf, ssl->in_left, + ssl->out_buf, MBEDTLS_SSL_OUT_CONTENT_LEN, &len); + + MBEDTLS_SSL_DEBUG_RET(2, "mbedtls_ssl_check_dtls_clihlo_cookie", ret); + + if (ret == MBEDTLS_ERR_SSL_HELLO_VERIFY_REQUIRED) { + int send_ret; + MBEDTLS_SSL_DEBUG_MSG(1, ("sending HelloVerifyRequest")); + MBEDTLS_SSL_DEBUG_BUF(4, "output record sent to network", + ssl->out_buf, len); + /* Don't check write errors as we can't do anything here. + * If the error is permanent we'll catch it later, + * if it's not, then hopefully it'll work next time. */ + send_ret = ssl->f_send(ssl->p_bio, ssl->out_buf, len); + MBEDTLS_SSL_DEBUG_RET(2, "ssl->f_send", send_ret); + (void) send_ret; + + return 0; + } + + if (ret == 0) { + MBEDTLS_SSL_DEBUG_MSG(1, ("cookie is valid, resetting context")); + if ((ret = mbedtls_ssl_session_reset_int(ssl, 1)) != 0) { + MBEDTLS_SSL_DEBUG_RET(1, "reset", ret); + return ret; + } + + return MBEDTLS_ERR_SSL_CLIENT_RECONNECT; + } + + return ret; +} +#endif /* MBEDTLS_SSL_DTLS_CLIENT_PORT_REUSE && MBEDTLS_SSL_SRV_C */ + +MBEDTLS_CHECK_RETURN_CRITICAL +static int ssl_check_record_type(uint8_t record_type) +{ + if (record_type != MBEDTLS_SSL_MSG_HANDSHAKE && + record_type != MBEDTLS_SSL_MSG_ALERT && + record_type != MBEDTLS_SSL_MSG_CHANGE_CIPHER_SPEC && + record_type != MBEDTLS_SSL_MSG_APPLICATION_DATA) { + return MBEDTLS_ERR_SSL_INVALID_RECORD; + } + + return 0; +} + +/* + * ContentType type; + * ProtocolVersion version; + * uint16 epoch; // DTLS only + * uint48 sequence_number; // DTLS only + * uint16 length; + * + * Return 0 if header looks sane (and, for DTLS, the record is expected) + * MBEDTLS_ERR_SSL_INVALID_RECORD if the header looks bad, + * MBEDTLS_ERR_SSL_UNEXPECTED_RECORD (DTLS only) if sane but unexpected. + * + * With DTLS, mbedtls_ssl_read_record() will: + * 1. proceed with the record if this function returns 0 + * 2. drop only the current record if this function returns UNEXPECTED_RECORD + * 3. return CLIENT_RECONNECT if this function return that value + * 4. drop the whole datagram if this function returns anything else. + * Point 2 is needed when the peer is resending, and we have already received + * the first record from a datagram but are still waiting for the others. + */ +MBEDTLS_CHECK_RETURN_CRITICAL +static int ssl_parse_record_header(mbedtls_ssl_context const *ssl, + unsigned char *buf, + size_t len, + mbedtls_record *rec) +{ + mbedtls_ssl_protocol_version tls_version; + + size_t const rec_hdr_type_offset = 0; + size_t const rec_hdr_type_len = 1; + + size_t const rec_hdr_version_offset = rec_hdr_type_offset + + rec_hdr_type_len; + size_t const rec_hdr_version_len = 2; + + size_t const rec_hdr_ctr_len = 8; +#if defined(MBEDTLS_SSL_PROTO_DTLS) + uint32_t rec_epoch; + size_t const rec_hdr_ctr_offset = rec_hdr_version_offset + + rec_hdr_version_len; + +#if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID) + size_t const rec_hdr_cid_offset = rec_hdr_ctr_offset + + rec_hdr_ctr_len; + size_t rec_hdr_cid_len = 0; +#endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID */ +#endif /* MBEDTLS_SSL_PROTO_DTLS */ + + size_t rec_hdr_len_offset; /* To be determined */ + size_t const rec_hdr_len_len = 2; + + /* + * Check minimum lengths for record header. + */ + +#if defined(MBEDTLS_SSL_PROTO_DTLS) + if (ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM) { + rec_hdr_len_offset = rec_hdr_ctr_offset + rec_hdr_ctr_len; + } else +#endif /* MBEDTLS_SSL_PROTO_DTLS */ + { + rec_hdr_len_offset = rec_hdr_version_offset + rec_hdr_version_len; + } + + if (len < rec_hdr_len_offset + rec_hdr_len_len) { + MBEDTLS_SSL_DEBUG_MSG(1, + ( + "datagram of length %u too small to hold DTLS record header of length %u", + (unsigned) len, + (unsigned) (rec_hdr_len_len + rec_hdr_len_len))); + return MBEDTLS_ERR_SSL_INVALID_RECORD; + } + + /* + * Parse and validate record content type + */ + + rec->type = buf[rec_hdr_type_offset]; + + /* Check record content type */ +#if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID) + rec->cid_len = 0; + + if (ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM && + ssl->conf->cid_len != 0 && + rec->type == MBEDTLS_SSL_MSG_CID) { + /* Shift pointers to account for record header including CID + * struct { + * ContentType outer_type = tls12_cid; + * ProtocolVersion version; + * uint16 epoch; + * uint48 sequence_number; + * opaque cid[cid_length]; // Additional field compared to + * // default DTLS record format + * uint16 length; + * opaque enc_content[DTLSCiphertext.length]; + * } DTLSCiphertext; + */ + + /* So far, we only support static CID lengths + * fixed in the configuration. */ + rec_hdr_cid_len = ssl->conf->cid_len; + rec_hdr_len_offset += rec_hdr_cid_len; + + if (len < rec_hdr_len_offset + rec_hdr_len_len) { + MBEDTLS_SSL_DEBUG_MSG(1, + ( + "datagram of length %u too small to hold DTLS record header including CID, length %u", + (unsigned) len, + (unsigned) (rec_hdr_len_offset + rec_hdr_len_len))); + return MBEDTLS_ERR_SSL_INVALID_RECORD; + } + + /* configured CID len is guaranteed at most 255, see + * MBEDTLS_SSL_CID_OUT_LEN_MAX in check_config.h */ + rec->cid_len = (uint8_t) rec_hdr_cid_len; + memcpy(rec->cid, buf + rec_hdr_cid_offset, rec_hdr_cid_len); + } else +#endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID */ + { + if (ssl_check_record_type(rec->type)) { + MBEDTLS_SSL_DEBUG_MSG(1, ("unknown record type %u", + (unsigned) rec->type)); + return MBEDTLS_ERR_SSL_INVALID_RECORD; + } + } + + /* + * Parse and validate record version + */ + rec->ver[0] = buf[rec_hdr_version_offset + 0]; + rec->ver[1] = buf[rec_hdr_version_offset + 1]; + tls_version = (mbedtls_ssl_protocol_version) mbedtls_ssl_read_version( + buf + rec_hdr_version_offset, + ssl->conf->transport); + + if (tls_version > ssl->conf->max_tls_version) { + MBEDTLS_SSL_DEBUG_MSG(1, ("TLS version mismatch: got %u, expected max %u", + (unsigned) tls_version, + (unsigned) ssl->conf->max_tls_version)); + + return MBEDTLS_ERR_SSL_INVALID_RECORD; + } + /* + * Parse/Copy record sequence number. + */ + +#if defined(MBEDTLS_SSL_PROTO_DTLS) + if (ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM) { + /* Copy explicit record sequence number from input buffer. */ + memcpy(&rec->ctr[0], buf + rec_hdr_ctr_offset, + rec_hdr_ctr_len); + } else +#endif /* MBEDTLS_SSL_PROTO_DTLS */ + { + /* Copy implicit record sequence number from SSL context structure. */ + memcpy(&rec->ctr[0], ssl->in_ctr, rec_hdr_ctr_len); + } + + /* + * Parse record length. + */ + + rec->data_offset = rec_hdr_len_offset + rec_hdr_len_len; + rec->data_len = MBEDTLS_GET_UINT16_BE(buf, rec_hdr_len_offset); + MBEDTLS_SSL_DEBUG_BUF(4, "input record header", buf, rec->data_offset); + + MBEDTLS_SSL_DEBUG_MSG(3, ("input record: msgtype = %u, " + "version = [0x%x], msglen = %" MBEDTLS_PRINTF_SIZET, + rec->type, (unsigned) tls_version, rec->data_len)); + + rec->buf = buf; + rec->buf_len = rec->data_offset + rec->data_len; + + if (rec->data_len == 0) { + return MBEDTLS_ERR_SSL_INVALID_RECORD; + } + + /* + * DTLS-related tests. + * Check epoch before checking length constraint because + * the latter varies with the epoch. E.g., if a ChangeCipherSpec + * message gets duplicated before the corresponding Finished message, + * the second ChangeCipherSpec should be discarded because it belongs + * to an old epoch, but not because its length is shorter than + * the minimum record length for packets using the new record transform. + * Note that these two kinds of failures are handled differently, + * as an unexpected record is silently skipped but an invalid + * record leads to the entire datagram being dropped. + */ +#if defined(MBEDTLS_SSL_PROTO_DTLS) + if (ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM) { + rec_epoch = MBEDTLS_GET_UINT16_BE(rec->ctr, 0); + + /* Check that the datagram is large enough to contain a record + * of the advertised length. */ + if (len < rec->data_offset + rec->data_len) { + MBEDTLS_SSL_DEBUG_MSG(1, + ( + "Datagram of length %u too small to contain record of advertised length %u.", + (unsigned) len, + (unsigned) (rec->data_offset + rec->data_len))); + return MBEDTLS_ERR_SSL_INVALID_RECORD; + } + + /* Records from other, non-matching epochs are silently discarded. + * (The case of same-port Client reconnects must be considered in + * the caller). */ + if (rec_epoch != ssl->in_epoch) { + MBEDTLS_SSL_DEBUG_MSG(1, ("record from another epoch: " + "expected %u, received %lu", + ssl->in_epoch, (unsigned long) rec_epoch)); + + /* Records from the next epoch are considered for buffering + * (concretely: early Finished messages). */ + if (rec_epoch == (unsigned) ssl->in_epoch + 1) { + MBEDTLS_SSL_DEBUG_MSG(2, ("Consider record for buffering")); + return MBEDTLS_ERR_SSL_EARLY_MESSAGE; + } + + return MBEDTLS_ERR_SSL_UNEXPECTED_RECORD; + } +#if defined(MBEDTLS_SSL_DTLS_ANTI_REPLAY) + /* For records from the correct epoch, check whether their + * sequence number has been seen before. */ + else if (mbedtls_ssl_dtls_record_replay_check((mbedtls_ssl_context *) ssl, + &rec->ctr[0]) != 0) { + MBEDTLS_SSL_DEBUG_MSG(1, ("replayed record")); + return MBEDTLS_ERR_SSL_UNEXPECTED_RECORD; + } +#endif + } +#endif /* MBEDTLS_SSL_PROTO_DTLS */ + + return 0; +} + + +#if defined(MBEDTLS_SSL_DTLS_CLIENT_PORT_REUSE) && defined(MBEDTLS_SSL_SRV_C) +MBEDTLS_CHECK_RETURN_CRITICAL +static int ssl_check_client_reconnect(mbedtls_ssl_context *ssl) +{ + unsigned int rec_epoch = MBEDTLS_GET_UINT16_BE(ssl->in_ctr, 0); + + /* + * Check for an epoch 0 ClientHello. We can't use in_msg here to + * access the first byte of record content (handshake type), as we + * have an active transform (possibly iv_len != 0), so use the + * fact that the record header len is 13 instead. + */ + if (rec_epoch == 0 && + ssl->conf->endpoint == MBEDTLS_SSL_IS_SERVER && + mbedtls_ssl_is_handshake_over(ssl) == 1 && + ssl->in_msgtype == MBEDTLS_SSL_MSG_HANDSHAKE && + ssl->in_left > 13 && + ssl->in_buf[13] == MBEDTLS_SSL_HS_CLIENT_HELLO) { + MBEDTLS_SSL_DEBUG_MSG(1, ("possible client reconnect " + "from the same port")); + return ssl_handle_possible_reconnect(ssl); + } + + return 0; +} +#endif /* MBEDTLS_SSL_DTLS_CLIENT_PORT_REUSE && MBEDTLS_SSL_SRV_C */ + +/* + * If applicable, decrypt record content + */ +MBEDTLS_CHECK_RETURN_CRITICAL +static int ssl_prepare_record_content(mbedtls_ssl_context *ssl, + mbedtls_record *rec) +{ + int ret, done = 0; + + MBEDTLS_SSL_DEBUG_BUF(4, "input record from network", + rec->buf, rec->buf_len); + + /* + * In TLS 1.3, always treat ChangeCipherSpec records + * as unencrypted. The only thing we do with them is + * check the length and content and ignore them. + */ +#if defined(MBEDTLS_SSL_PROTO_TLS1_3) + if (ssl->transform_in != NULL && + ssl->transform_in->tls_version == MBEDTLS_SSL_VERSION_TLS1_3) { + if (rec->type == MBEDTLS_SSL_MSG_CHANGE_CIPHER_SPEC) { + done = 1; + } + } +#endif /* MBEDTLS_SSL_PROTO_TLS1_3 */ + + if (!done && ssl->transform_in != NULL) { + unsigned char const old_msg_type = rec->type; + + if ((ret = mbedtls_ssl_decrypt_buf(ssl, ssl->transform_in, + rec)) != 0) { + MBEDTLS_SSL_DEBUG_RET(1, "ssl_decrypt_buf", ret); + +#if defined(MBEDTLS_SSL_EARLY_DATA) && defined(MBEDTLS_SSL_SRV_C) + /* + * Although the server rejected early data, it might receive early + * data as long as it has not received the client Finished message. + * It is encrypted with early keys and should be ignored as stated + * in section 4.2.10 of RFC 8446: + * + * "Ignore the extension and return a regular 1-RTT response. The + * server then skips past early data by attempting to deprotect + * received records using the handshake traffic key, discarding + * records which fail deprotection (up to the configured + * max_early_data_size). Once a record is deprotected successfully, + * it is treated as the start of the client's second flight and the + * server proceeds as with an ordinary 1-RTT handshake." + */ + if ((old_msg_type == MBEDTLS_SSL_MSG_APPLICATION_DATA) && + (ssl->discard_early_data_record == + MBEDTLS_SSL_EARLY_DATA_TRY_TO_DEPROTECT_AND_DISCARD)) { + MBEDTLS_SSL_DEBUG_MSG( + 3, ("EarlyData: deprotect and discard app data records.")); + + ret = mbedtls_ssl_tls13_check_early_data_len(ssl, rec->data_len); + if (ret != 0) { + return ret; + } + ret = MBEDTLS_ERR_SSL_CONTINUE_PROCESSING; + } +#endif /* MBEDTLS_SSL_EARLY_DATA && MBEDTLS_SSL_SRV_C */ + +#if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID) + if (ret == MBEDTLS_ERR_SSL_UNEXPECTED_CID && + ssl->conf->ignore_unexpected_cid + == MBEDTLS_SSL_UNEXPECTED_CID_IGNORE) { + MBEDTLS_SSL_DEBUG_MSG(3, ("ignoring unexpected CID")); + ret = MBEDTLS_ERR_SSL_CONTINUE_PROCESSING; + } +#endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID */ + + /* + * The decryption of the record failed, no reason to ignore it, + * return in error with the decryption error code. + */ + return ret; + } + +#if defined(MBEDTLS_SSL_EARLY_DATA) && defined(MBEDTLS_SSL_SRV_C) + /* + * If the server were discarding protected records that it fails to + * deprotect because it has rejected early data, as we have just + * deprotected successfully a record, the server has to resume normal + * operation and fail the connection if the deprotection of a record + * fails. + */ + if (ssl->discard_early_data_record == + MBEDTLS_SSL_EARLY_DATA_TRY_TO_DEPROTECT_AND_DISCARD) { + ssl->discard_early_data_record = MBEDTLS_SSL_EARLY_DATA_NO_DISCARD; + } +#endif /* MBEDTLS_SSL_EARLY_DATA && MBEDTLS_SSL_SRV_C */ + + if (old_msg_type != rec->type) { + MBEDTLS_SSL_DEBUG_MSG(4, ("record type after decrypt (before %d): %d", + old_msg_type, rec->type)); + } + + MBEDTLS_SSL_DEBUG_BUF(4, "input payload after decrypt", + rec->buf + rec->data_offset, rec->data_len); + +#if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID) + /* We have already checked the record content type + * in ssl_parse_record_header(), failing or silently + * dropping the record in the case of an unknown type. + * + * Since with the use of CIDs, the record content type + * might change during decryption, re-check the record + * content type, but treat a failure as fatal this time. */ + if (ssl_check_record_type(rec->type)) { + MBEDTLS_SSL_DEBUG_MSG(1, ("unknown record type")); + return MBEDTLS_ERR_SSL_INVALID_RECORD; + } +#endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID */ + + if (rec->data_len == 0) { +#if defined(MBEDTLS_SSL_PROTO_TLS1_2) + if (ssl->tls_version == MBEDTLS_SSL_VERSION_TLS1_2 + && rec->type != MBEDTLS_SSL_MSG_APPLICATION_DATA) { + /* TLS v1.2 explicitly disallows zero-length messages which are not application data */ + MBEDTLS_SSL_DEBUG_MSG(1, ("invalid zero-length message type: %d", ssl->in_msgtype)); + return MBEDTLS_ERR_SSL_INVALID_RECORD; + } +#endif /* MBEDTLS_SSL_PROTO_TLS1_2 */ + + ssl->nb_zero++; + + /* + * Three or more empty messages may be a DoS attack + * (excessive CPU consumption). + */ + if (ssl->nb_zero > 3) { + MBEDTLS_SSL_DEBUG_MSG(1, ("received four consecutive empty " + "messages, possible DoS attack")); + /* Treat the records as if they were not properly authenticated, + * thereby failing the connection if we see more than allowed + * by the configured bad MAC threshold. */ + return MBEDTLS_ERR_SSL_INVALID_MAC; + } + } else { + ssl->nb_zero = 0; + } + +#if defined(MBEDTLS_SSL_PROTO_DTLS) + if (ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM) { + ; /* in_ctr read from peer, not maintained internally */ + } else +#endif + { + unsigned i; + for (i = MBEDTLS_SSL_SEQUENCE_NUMBER_LEN; + i > mbedtls_ssl_ep_len(ssl); i--) { + if (++ssl->in_ctr[i - 1] != 0) { + break; + } + } + + /* The loop goes to its end iff the counter is wrapping */ + if (i == mbedtls_ssl_ep_len(ssl)) { + MBEDTLS_SSL_DEBUG_MSG(1, ("incoming message counter would wrap")); + return MBEDTLS_ERR_SSL_COUNTER_WRAPPING; + } + } + + } + +#if defined(MBEDTLS_SSL_EARLY_DATA) && defined(MBEDTLS_SSL_SRV_C) + /* + * Although the server rejected early data because it needed to send an + * HelloRetryRequest message, it might receive early data as long as it has + * not received the client Finished message. + * The early data is encrypted with early keys and should be ignored as + * stated in section 4.2.10 of RFC 8446 (second case): + * + * "The server then ignores early data by skipping all records with an + * external content type of "application_data" (indicating that they are + * encrypted), up to the configured max_early_data_size. Ignore application + * data message before 2nd ClientHello when early_data was received in 1st + * ClientHello." + */ + if (ssl->discard_early_data_record == MBEDTLS_SSL_EARLY_DATA_DISCARD) { + if (rec->type == MBEDTLS_SSL_MSG_APPLICATION_DATA) { + + ret = mbedtls_ssl_tls13_check_early_data_len(ssl, rec->data_len); + if (ret != 0) { + return ret; + } + + MBEDTLS_SSL_DEBUG_MSG( + 3, ("EarlyData: Ignore application message before 2nd ClientHello")); + + return MBEDTLS_ERR_SSL_CONTINUE_PROCESSING; + } else if (rec->type == MBEDTLS_SSL_MSG_HANDSHAKE) { + ssl->discard_early_data_record = MBEDTLS_SSL_EARLY_DATA_NO_DISCARD; + } + } +#endif /* MBEDTLS_SSL_EARLY_DATA && MBEDTLS_SSL_SRV_C */ + +#if defined(MBEDTLS_SSL_DTLS_ANTI_REPLAY) + if (ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM) { + mbedtls_ssl_dtls_replay_update(ssl); + } +#endif + + /* Check actual (decrypted) record content length against + * configured maximum. */ + if (rec->data_len > MBEDTLS_SSL_IN_CONTENT_LEN) { + MBEDTLS_SSL_DEBUG_MSG(1, ("bad message length")); + return MBEDTLS_ERR_SSL_INVALID_RECORD; + } + + return 0; +} + +/* + * Read a record. + * + * Silently ignore non-fatal alert (and for DTLS, invalid records as well, + * RFC 6347 4.1.2.7) and continue reading until a valid record is found. + * + */ + +/* Helper functions for mbedtls_ssl_read_record(). */ +MBEDTLS_CHECK_RETURN_CRITICAL +static int ssl_consume_current_message(mbedtls_ssl_context *ssl); +MBEDTLS_CHECK_RETURN_CRITICAL +static int ssl_get_next_record(mbedtls_ssl_context *ssl); +MBEDTLS_CHECK_RETURN_CRITICAL +static int ssl_record_is_in_progress(mbedtls_ssl_context *ssl); + +int mbedtls_ssl_read_record(mbedtls_ssl_context *ssl, + unsigned update_hs_digest) +{ + int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; + + MBEDTLS_SSL_DEBUG_MSG(2, ("=> read record")); + + if (ssl->keep_current_message == 0) { + do { + + ret = ssl_consume_current_message(ssl); + if (ret != 0) { + return ret; + } + + if (ssl_record_is_in_progress(ssl) == 0) { + int dtls_have_buffered = 0; +#if defined(MBEDTLS_SSL_PROTO_DTLS) + + /* We only check for buffered messages if the + * current datagram is fully consumed. */ + if (ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM && + ssl_next_record_is_in_datagram(ssl) == 0) { + if (ssl_load_buffered_message(ssl) == 0) { + dtls_have_buffered = 1; + } + } + +#endif /* MBEDTLS_SSL_PROTO_DTLS */ + if (dtls_have_buffered == 0) { + ret = ssl_get_next_record(ssl); + if (ret == MBEDTLS_ERR_SSL_CONTINUE_PROCESSING) { + continue; + } + + if (ret != 0) { + MBEDTLS_SSL_DEBUG_RET(1, ("ssl_get_next_record"), ret); + return ret; + } + } + } + + ret = mbedtls_ssl_handle_message_type(ssl); + +#if defined(MBEDTLS_SSL_PROTO_DTLS) + if (ret == MBEDTLS_ERR_SSL_EARLY_MESSAGE) { + /* Buffer future message */ + ret = ssl_buffer_message(ssl); + if (ret != 0) { + return ret; + } + + ret = MBEDTLS_ERR_SSL_CONTINUE_PROCESSING; + } +#endif /* MBEDTLS_SSL_PROTO_DTLS */ + + } while (MBEDTLS_ERR_SSL_NON_FATAL == ret || + MBEDTLS_ERR_SSL_CONTINUE_PROCESSING == ret); + + if (0 != ret) { + MBEDTLS_SSL_DEBUG_RET(1, ("mbedtls_ssl_handle_message_type"), ret); + return ret; + } + + if (ssl->in_msgtype == MBEDTLS_SSL_MSG_HANDSHAKE && + update_hs_digest == 1) { + ret = mbedtls_ssl_update_handshake_status(ssl); + if (0 != ret) { + MBEDTLS_SSL_DEBUG_RET(1, ("mbedtls_ssl_update_handshake_status"), ret); + return ret; + } + } + } else { + MBEDTLS_SSL_DEBUG_MSG(2, ("reuse previously read message")); + ssl->keep_current_message = 0; + } + + MBEDTLS_SSL_DEBUG_MSG(2, ("<= read record")); + + return 0; +} + +#if defined(MBEDTLS_SSL_PROTO_DTLS) +MBEDTLS_CHECK_RETURN_CRITICAL +static int ssl_next_record_is_in_datagram(mbedtls_ssl_context *ssl) +{ + if (ssl->in_left > ssl->next_record_offset) { + return 1; + } + + return 0; +} + +MBEDTLS_CHECK_RETURN_CRITICAL +static int ssl_load_buffered_message(mbedtls_ssl_context *ssl) +{ + mbedtls_ssl_handshake_params * const hs = ssl->handshake; + mbedtls_ssl_hs_buffer *hs_buf; + int ret = 0; + + if (hs == NULL) { + return -1; + } + + MBEDTLS_SSL_DEBUG_MSG(2, ("=> ssl_load_buffered_message")); + + if (ssl->state == MBEDTLS_SSL_CLIENT_CHANGE_CIPHER_SPEC || + ssl->state == MBEDTLS_SSL_SERVER_CHANGE_CIPHER_SPEC) { + /* Check if we have seen a ChangeCipherSpec before. + * If yes, synthesize a CCS record. */ + if (!hs->buffering.seen_ccs) { + MBEDTLS_SSL_DEBUG_MSG(2, ("CCS not seen in the current flight")); + ret = -1; + goto exit; + } + + MBEDTLS_SSL_DEBUG_MSG(2, ("Injecting buffered CCS message")); + ssl->in_msgtype = MBEDTLS_SSL_MSG_CHANGE_CIPHER_SPEC; + ssl->in_msglen = 1; + ssl->in_msg[0] = 1; + + /* As long as they are equal, the exact value doesn't matter. */ + ssl->in_left = 0; + ssl->next_record_offset = 0; + + hs->buffering.seen_ccs = 0; + goto exit; + } + +#if defined(MBEDTLS_DEBUG_C) + /* Debug only */ + { + unsigned offset; + for (offset = 1; offset < MBEDTLS_SSL_MAX_BUFFERED_HS; offset++) { + hs_buf = &hs->buffering.hs[offset]; + if (hs_buf->is_valid == 1) { + MBEDTLS_SSL_DEBUG_MSG(2, ("Future message with sequence number %u %s buffered.", + hs->in_msg_seq + offset, + hs_buf->is_complete ? "fully" : "partially")); + } + } + } +#endif /* MBEDTLS_DEBUG_C */ + + /* Check if we have buffered and/or fully reassembled the + * next handshake message. */ + hs_buf = &hs->buffering.hs[0]; + if ((hs_buf->is_valid == 1) && (hs_buf->is_complete == 1)) { + /* Synthesize a record containing the buffered HS message. */ + size_t msg_len = MBEDTLS_GET_UINT24_BE(hs_buf->data, 1); + + /* Double-check that we haven't accidentally buffered + * a message that doesn't fit into the input buffer. */ + if (msg_len + 12 > MBEDTLS_SSL_IN_CONTENT_LEN) { + MBEDTLS_SSL_DEBUG_MSG(1, ("should never happen")); + return MBEDTLS_ERR_SSL_INTERNAL_ERROR; + } + + MBEDTLS_SSL_DEBUG_MSG(2, ("Next handshake message has been buffered - load")); + MBEDTLS_SSL_DEBUG_BUF(3, "Buffered handshake message (incl. header)", + hs_buf->data, msg_len + 12); + + ssl->in_msgtype = MBEDTLS_SSL_MSG_HANDSHAKE; + ssl->in_hslen = msg_len + 12; + ssl->in_msglen = msg_len + 12; + memcpy(ssl->in_msg, hs_buf->data, ssl->in_hslen); + + ret = 0; + goto exit; + } else { + MBEDTLS_SSL_DEBUG_MSG(2, ("Next handshake message %u not or only partially bufffered", + hs->in_msg_seq)); + } + + ret = -1; + +exit: + + MBEDTLS_SSL_DEBUG_MSG(2, ("<= ssl_load_buffered_message")); + return ret; +} + +MBEDTLS_CHECK_RETURN_CRITICAL +static int ssl_buffer_make_space(mbedtls_ssl_context *ssl, + size_t desired) +{ + int offset; + mbedtls_ssl_handshake_params * const hs = ssl->handshake; + MBEDTLS_SSL_DEBUG_MSG(2, ("Attempt to free buffered messages to have %u bytes available", + (unsigned) desired)); + + /* Get rid of future records epoch first, if such exist. */ + ssl_free_buffered_record(ssl); + + /* Check if we have enough space available now. */ + if (desired <= (MBEDTLS_SSL_DTLS_MAX_BUFFERING - + hs->buffering.total_bytes_buffered)) { + MBEDTLS_SSL_DEBUG_MSG(2, ("Enough space available after freeing future epoch record")); + return 0; + } + + /* We don't have enough space to buffer the next expected handshake + * message. Remove buffers used for future messages to gain space, + * starting with the most distant one. */ + for (offset = MBEDTLS_SSL_MAX_BUFFERED_HS - 1; + offset >= 0; offset--) { + MBEDTLS_SSL_DEBUG_MSG(2, + ( + "Free buffering slot %d to make space for reassembly of next handshake message", + offset)); + + ssl_buffering_free_slot(ssl, (uint8_t) offset); + + /* Check if we have enough space available now. */ + if (desired <= (MBEDTLS_SSL_DTLS_MAX_BUFFERING - + hs->buffering.total_bytes_buffered)) { + MBEDTLS_SSL_DEBUG_MSG(2, ("Enough space available after freeing buffered HS messages")); + return 0; + } + } + + return -1; +} + +MBEDTLS_CHECK_RETURN_CRITICAL +static int ssl_buffer_message(mbedtls_ssl_context *ssl) +{ + int ret = 0; + mbedtls_ssl_handshake_params * const hs = ssl->handshake; + + if (hs == NULL) { + return 0; + } + + MBEDTLS_SSL_DEBUG_MSG(2, ("=> ssl_buffer_message")); + + switch (ssl->in_msgtype) { + case MBEDTLS_SSL_MSG_CHANGE_CIPHER_SPEC: + MBEDTLS_SSL_DEBUG_MSG(2, ("Remember CCS message")); + + hs->buffering.seen_ccs = 1; + break; + + case MBEDTLS_SSL_MSG_HANDSHAKE: + { + unsigned recv_msg_seq_offset; + unsigned recv_msg_seq = MBEDTLS_GET_UINT16_BE(ssl->in_msg, 4); + mbedtls_ssl_hs_buffer *hs_buf; + size_t msg_len = ssl->in_hslen - 12; + + /* We should never receive an old handshake + * message - double-check nonetheless. */ + if (recv_msg_seq < ssl->handshake->in_msg_seq) { + MBEDTLS_SSL_DEBUG_MSG(1, ("should never happen")); + return MBEDTLS_ERR_SSL_INTERNAL_ERROR; + } + + recv_msg_seq_offset = recv_msg_seq - ssl->handshake->in_msg_seq; + if (recv_msg_seq_offset >= MBEDTLS_SSL_MAX_BUFFERED_HS) { + /* Silently ignore -- message too far in the future */ + MBEDTLS_SSL_DEBUG_MSG(2, + ("Ignore future HS message with sequence number %u, " + "buffering window %u - %u", + recv_msg_seq, ssl->handshake->in_msg_seq, + ssl->handshake->in_msg_seq + MBEDTLS_SSL_MAX_BUFFERED_HS - + 1)); + + goto exit; + } + + MBEDTLS_SSL_DEBUG_MSG(2, ("Buffering HS message with sequence number %u, offset %u ", + recv_msg_seq, recv_msg_seq_offset)); + + hs_buf = &hs->buffering.hs[recv_msg_seq_offset]; + + /* Check if the buffering for this seq nr has already commenced. */ + if (!hs_buf->is_valid) { + size_t reassembly_buf_sz; + + hs_buf->is_fragmented = + (ssl_hs_is_proper_fragment(ssl) == 1); + + /* We copy the message back into the input buffer + * after reassembly, so check that it's not too large. + * This is an implementation-specific limitation + * and not one from the standard, hence it is not + * checked in ssl_check_hs_header(). */ + if (msg_len + 12 > MBEDTLS_SSL_IN_CONTENT_LEN) { + /* Ignore message */ + goto exit; + } + + /* Check if we have enough space to buffer the message. */ + if (hs->buffering.total_bytes_buffered > + MBEDTLS_SSL_DTLS_MAX_BUFFERING) { + MBEDTLS_SSL_DEBUG_MSG(1, ("should never happen")); + return MBEDTLS_ERR_SSL_INTERNAL_ERROR; + } + + reassembly_buf_sz = ssl_get_reassembly_buffer_size(msg_len, + hs_buf->is_fragmented); + + if (reassembly_buf_sz > (MBEDTLS_SSL_DTLS_MAX_BUFFERING - + hs->buffering.total_bytes_buffered)) { + if (recv_msg_seq_offset > 0) { + /* If we can't buffer a future message because + * of space limitations -- ignore. */ + MBEDTLS_SSL_DEBUG_MSG(2, + ("Buffering of future message of size %" + MBEDTLS_PRINTF_SIZET + " would exceed the compile-time limit %" + MBEDTLS_PRINTF_SIZET + " (already %" MBEDTLS_PRINTF_SIZET + " bytes buffered) -- ignore\n", + msg_len, (size_t) MBEDTLS_SSL_DTLS_MAX_BUFFERING, + hs->buffering.total_bytes_buffered)); + goto exit; + } else { + MBEDTLS_SSL_DEBUG_MSG(2, + ("Buffering of future message of size %" + MBEDTLS_PRINTF_SIZET + " would exceed the compile-time limit %" + MBEDTLS_PRINTF_SIZET + " (already %" MBEDTLS_PRINTF_SIZET + " bytes buffered) -- attempt to make space by freeing buffered future messages\n", + msg_len, (size_t) MBEDTLS_SSL_DTLS_MAX_BUFFERING, + hs->buffering.total_bytes_buffered)); + } + + if (ssl_buffer_make_space(ssl, reassembly_buf_sz) != 0) { + MBEDTLS_SSL_DEBUG_MSG(2, + ("Reassembly of next message of size %" + MBEDTLS_PRINTF_SIZET + " (%" MBEDTLS_PRINTF_SIZET + " with bitmap) would exceed" + " the compile-time limit %" + MBEDTLS_PRINTF_SIZET + " (already %" MBEDTLS_PRINTF_SIZET + " bytes buffered) -- fail\n", + msg_len, + reassembly_buf_sz, + (size_t) MBEDTLS_SSL_DTLS_MAX_BUFFERING, + hs->buffering.total_bytes_buffered)); + ret = MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL; + goto exit; + } + } + + MBEDTLS_SSL_DEBUG_MSG(2, + ("initialize reassembly, total length = %" + MBEDTLS_PRINTF_SIZET, + msg_len)); + + hs_buf->data = mbedtls_calloc(1, reassembly_buf_sz); + if (hs_buf->data == NULL) { + ret = MBEDTLS_ERR_SSL_ALLOC_FAILED; + goto exit; + } + hs_buf->data_len = reassembly_buf_sz; + + /* Prepare final header: copy msg_type, length and message_seq, + * then add standardised fragment_offset and fragment_length */ + memcpy(hs_buf->data, ssl->in_msg, 6); + memset(hs_buf->data + 6, 0, 3); + memcpy(hs_buf->data + 9, hs_buf->data + 1, 3); + + hs_buf->is_valid = 1; + + hs->buffering.total_bytes_buffered += reassembly_buf_sz; + } else { + /* Make sure msg_type and length are consistent */ + if (memcmp(hs_buf->data, ssl->in_msg, 4) != 0) { + MBEDTLS_SSL_DEBUG_MSG(1, ("Fragment header mismatch - ignore")); + /* Ignore */ + goto exit; + } + } + + if (!hs_buf->is_complete) { + size_t frag_len, frag_off; + unsigned char * const msg = hs_buf->data + 12; + + /* + * Check and copy current fragment + */ + + /* Validation of header fields already done in + * mbedtls_ssl_prepare_handshake_record(). */ + frag_off = ssl_get_hs_frag_off(ssl); + frag_len = ssl_get_hs_frag_len(ssl); + + MBEDTLS_SSL_DEBUG_MSG(2, ("adding fragment, offset = %" MBEDTLS_PRINTF_SIZET + ", length = %" MBEDTLS_PRINTF_SIZET, + frag_off, frag_len)); + memcpy(msg + frag_off, ssl->in_msg + 12, frag_len); + + if (hs_buf->is_fragmented) { + unsigned char * const bitmask = msg + msg_len; + ssl_bitmask_set(bitmask, frag_off, frag_len); + hs_buf->is_complete = (ssl_bitmask_check(bitmask, + msg_len) == 0); + } else { + hs_buf->is_complete = 1; + } + + MBEDTLS_SSL_DEBUG_MSG(2, ("message %scomplete", + hs_buf->is_complete ? "" : "not yet ")); + } + + break; + } + + default: + /* We don't buffer other types of messages. */ + break; + } + +exit: + + MBEDTLS_SSL_DEBUG_MSG(2, ("<= ssl_buffer_message")); + return ret; +} +#endif /* MBEDTLS_SSL_PROTO_DTLS */ + +MBEDTLS_CHECK_RETURN_CRITICAL +static int ssl_consume_current_message(mbedtls_ssl_context *ssl) +{ + /* + * Consume last content-layer message and potentially + * update in_msglen which keeps track of the contents' + * consumption state. + * + * (1) Handshake messages: + * Remove last handshake message, move content + * and adapt in_msglen. + * + * (2) Alert messages: + * Consume whole record content, in_msglen = 0. + * + * (3) Change cipher spec: + * Consume whole record content, in_msglen = 0. + * + * (4) Application data: + * Don't do anything - the record layer provides + * the application data as a stream transport + * and consumes through mbedtls_ssl_read only. + * + */ + + /* Case (1): Handshake messages */ + if (ssl->in_hslen != 0) { + /* Hard assertion to be sure that no application data + * is in flight, as corrupting ssl->in_msglen during + * ssl->in_offt != NULL is fatal. */ + if (ssl->in_offt != NULL) { + MBEDTLS_SSL_DEBUG_MSG(1, ("should never happen")); + return MBEDTLS_ERR_SSL_INTERNAL_ERROR; + } + + /* + * Get next Handshake message in the current record + */ + + /* Notes: + * (1) in_hslen is not necessarily the size of the + * current handshake content: If DTLS handshake + * fragmentation is used, that's the fragment + * size instead. Using the total handshake message + * size here is faulty and should be changed at + * some point. + * (2) While it doesn't seem to cause problems, one + * has to be very careful not to assume that in_hslen + * is always <= in_msglen in a sensible communication. + * Again, it's wrong for DTLS handshake fragmentation. + * The following check is therefore mandatory, and + * should not be treated as a silently corrected assertion. + * Additionally, ssl->in_hslen might be arbitrarily out of + * bounds after handling a DTLS message with an unexpected + * sequence number, see mbedtls_ssl_prepare_handshake_record. + */ + if (ssl->in_hslen < ssl->in_msglen) { + ssl->in_msglen -= ssl->in_hslen; + memmove(ssl->in_msg, ssl->in_msg + ssl->in_hslen, + ssl->in_msglen); + + MBEDTLS_SSL_DEBUG_BUF(4, "remaining content in record", + ssl->in_msg, ssl->in_msglen); + } else { + ssl->in_msglen = 0; + } + + ssl->in_hslen = 0; + } + /* Case (4): Application data */ + else if (ssl->in_offt != NULL) { + return 0; + } + /* Everything else (CCS & Alerts) */ + else { + ssl->in_msglen = 0; + } + + return 0; +} + +MBEDTLS_CHECK_RETURN_CRITICAL +static int ssl_record_is_in_progress(mbedtls_ssl_context *ssl) +{ + if (ssl->in_msglen > 0) { + return 1; + } + + return 0; +} + +#if defined(MBEDTLS_SSL_PROTO_DTLS) + +static void ssl_free_buffered_record(mbedtls_ssl_context *ssl) +{ + mbedtls_ssl_handshake_params * const hs = ssl->handshake; + if (hs == NULL) { + return; + } + + if (hs->buffering.future_record.data != NULL) { + hs->buffering.total_bytes_buffered -= + hs->buffering.future_record.len; + + mbedtls_free(hs->buffering.future_record.data); + hs->buffering.future_record.data = NULL; + } +} + +MBEDTLS_CHECK_RETURN_CRITICAL +static int ssl_load_buffered_record(mbedtls_ssl_context *ssl) +{ + mbedtls_ssl_handshake_params * const hs = ssl->handshake; + unsigned char *rec; + size_t rec_len; + unsigned rec_epoch; +#if defined(MBEDTLS_SSL_VARIABLE_BUFFER_LENGTH) + size_t in_buf_len = ssl->in_buf_len; +#else + size_t in_buf_len = MBEDTLS_SSL_IN_BUFFER_LEN; +#endif + if (ssl->conf->transport != MBEDTLS_SSL_TRANSPORT_DATAGRAM) { + return 0; + } + + if (hs == NULL) { + return 0; + } + + rec = hs->buffering.future_record.data; + rec_len = hs->buffering.future_record.len; + rec_epoch = hs->buffering.future_record.epoch; + + if (rec == NULL) { + return 0; + } + + /* Only consider loading future records if the + * input buffer is empty. */ + if (ssl_next_record_is_in_datagram(ssl) == 1) { + return 0; + } + + MBEDTLS_SSL_DEBUG_MSG(2, ("=> ssl_load_buffered_record")); + + if (rec_epoch != ssl->in_epoch) { + MBEDTLS_SSL_DEBUG_MSG(2, ("Buffered record not from current epoch.")); + goto exit; + } + + MBEDTLS_SSL_DEBUG_MSG(2, ("Found buffered record from current epoch - load")); + + /* Double-check that the record is not too large */ + if (rec_len > in_buf_len - (size_t) (ssl->in_hdr - ssl->in_buf)) { + MBEDTLS_SSL_DEBUG_MSG(1, ("should never happen")); + return MBEDTLS_ERR_SSL_INTERNAL_ERROR; + } + + memcpy(ssl->in_hdr, rec, rec_len); + ssl->in_left = rec_len; + ssl->next_record_offset = 0; + + ssl_free_buffered_record(ssl); + +exit: + MBEDTLS_SSL_DEBUG_MSG(2, ("<= ssl_load_buffered_record")); + return 0; +} + +MBEDTLS_CHECK_RETURN_CRITICAL +static int ssl_buffer_future_record(mbedtls_ssl_context *ssl, + mbedtls_record const *rec) +{ + mbedtls_ssl_handshake_params * const hs = ssl->handshake; + + /* Don't buffer future records outside handshakes. */ + if (hs == NULL) { + return 0; + } + + /* Only buffer handshake records (we are only interested + * in Finished messages). */ + if (rec->type != MBEDTLS_SSL_MSG_HANDSHAKE) { + return 0; + } + + /* Don't buffer more than one future epoch record. */ + if (hs->buffering.future_record.data != NULL) { + return 0; + } + + /* Don't buffer record if there's not enough buffering space remaining. */ + if (rec->buf_len > (MBEDTLS_SSL_DTLS_MAX_BUFFERING - + hs->buffering.total_bytes_buffered)) { + MBEDTLS_SSL_DEBUG_MSG(2, ("Buffering of future epoch record of size %" MBEDTLS_PRINTF_SIZET + " would exceed the compile-time limit %" MBEDTLS_PRINTF_SIZET + " (already %" MBEDTLS_PRINTF_SIZET + " bytes buffered) -- ignore\n", + rec->buf_len, (size_t) MBEDTLS_SSL_DTLS_MAX_BUFFERING, + hs->buffering.total_bytes_buffered)); + return 0; + } + + /* Buffer record */ + MBEDTLS_SSL_DEBUG_MSG(2, ("Buffer record from epoch %u", + ssl->in_epoch + 1U)); + MBEDTLS_SSL_DEBUG_BUF(3, "Buffered record", rec->buf, rec->buf_len); + + /* ssl_parse_record_header() only considers records + * of the next epoch as candidates for buffering. */ + hs->buffering.future_record.epoch = ssl->in_epoch + 1; + hs->buffering.future_record.len = rec->buf_len; + + hs->buffering.future_record.data = + mbedtls_calloc(1, hs->buffering.future_record.len); + if (hs->buffering.future_record.data == NULL) { + /* If we run out of RAM trying to buffer a + * record from the next epoch, just ignore. */ + return 0; + } + + memcpy(hs->buffering.future_record.data, rec->buf, rec->buf_len); + + hs->buffering.total_bytes_buffered += rec->buf_len; + return 0; +} + +#endif /* MBEDTLS_SSL_PROTO_DTLS */ + +MBEDTLS_CHECK_RETURN_CRITICAL +static int ssl_get_next_record(mbedtls_ssl_context *ssl) +{ + int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; + mbedtls_record rec; + +#if defined(MBEDTLS_SSL_PROTO_DTLS) + /* We might have buffered a future record; if so, + * and if the epoch matches now, load it. + * On success, this call will set ssl->in_left to + * the length of the buffered record, so that + * the calls to ssl_fetch_input() below will + * essentially be no-ops. */ + ret = ssl_load_buffered_record(ssl); + if (ret != 0) { + return ret; + } +#endif /* MBEDTLS_SSL_PROTO_DTLS */ + + /* Ensure that we have enough space available for the default form + * of TLS / DTLS record headers (5 Bytes for TLS, 13 Bytes for DTLS, + * with no space for CIDs counted in). */ + ret = mbedtls_ssl_fetch_input(ssl, mbedtls_ssl_in_hdr_len(ssl)); + if (ret != 0) { + MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_ssl_fetch_input", ret); + return ret; + } + + ret = ssl_parse_record_header(ssl, ssl->in_hdr, ssl->in_left, &rec); + if (ret != 0) { +#if defined(MBEDTLS_SSL_PROTO_DTLS) + if (ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM) { + if (ret == MBEDTLS_ERR_SSL_EARLY_MESSAGE) { + ret = ssl_buffer_future_record(ssl, &rec); + if (ret != 0) { + return ret; + } + + /* Fall through to handling of unexpected records */ + ret = MBEDTLS_ERR_SSL_UNEXPECTED_RECORD; + } + + if (ret == MBEDTLS_ERR_SSL_UNEXPECTED_RECORD) { +#if defined(MBEDTLS_SSL_DTLS_CLIENT_PORT_REUSE) && defined(MBEDTLS_SSL_SRV_C) + /* Reset in pointers to default state for TLS/DTLS records, + * assuming no CID and no offset between record content and + * record plaintext. */ + mbedtls_ssl_update_in_pointers(ssl); + + /* Setup internal message pointers from record structure. */ + ssl->in_msgtype = rec.type; +#if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID) + ssl->in_len = ssl->in_cid + rec.cid_len; +#endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID */ + ssl->in_iv = ssl->in_msg = ssl->in_len + 2; + ssl->in_msglen = rec.data_len; + + ret = ssl_check_client_reconnect(ssl); + MBEDTLS_SSL_DEBUG_RET(2, "ssl_check_client_reconnect", ret); + if (ret != 0) { + return ret; + } +#endif + + /* Skip unexpected record (but not whole datagram) */ + ssl->next_record_offset = rec.buf_len; + + MBEDTLS_SSL_DEBUG_MSG(1, ("discarding unexpected record " + "(header)")); + } else { + /* Skip invalid record and the rest of the datagram */ + ssl->next_record_offset = 0; + ssl->in_left = 0; + + MBEDTLS_SSL_DEBUG_MSG(1, ("discarding invalid record " + "(header)")); + } + + /* Get next record */ + return MBEDTLS_ERR_SSL_CONTINUE_PROCESSING; + } else +#endif + { + return ret; + } + } + +#if defined(MBEDTLS_SSL_PROTO_DTLS) + if (ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM) { + /* Remember offset of next record within datagram. */ + ssl->next_record_offset = rec.buf_len; + if (ssl->next_record_offset < ssl->in_left) { + MBEDTLS_SSL_DEBUG_MSG(3, ("more than one record within datagram")); + } + } else +#endif + { + /* + * Fetch record contents from underlying transport. + */ + ret = mbedtls_ssl_fetch_input(ssl, rec.buf_len); + if (ret != 0) { + MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_ssl_fetch_input", ret); + return ret; + } + + ssl->in_left = 0; + } + + /* + * Decrypt record contents. + */ + + if ((ret = ssl_prepare_record_content(ssl, &rec)) != 0) { +#if defined(MBEDTLS_SSL_PROTO_DTLS) + if (ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM) { + /* Silently discard invalid records */ + if (ret == MBEDTLS_ERR_SSL_INVALID_MAC) { + /* Except when waiting for Finished as a bad mac here + * probably means something went wrong in the handshake + * (eg wrong psk used, mitm downgrade attempt, etc.) */ + if (ssl->state == MBEDTLS_SSL_CLIENT_FINISHED || + ssl->state == MBEDTLS_SSL_SERVER_FINISHED) { +#if defined(MBEDTLS_SSL_ALL_ALERT_MESSAGES) + if (ret == MBEDTLS_ERR_SSL_INVALID_MAC) { + mbedtls_ssl_send_alert_message(ssl, + MBEDTLS_SSL_ALERT_LEVEL_FATAL, + MBEDTLS_SSL_ALERT_MSG_BAD_RECORD_MAC); + } +#endif + return ret; + } + + if (ssl->conf->badmac_limit != 0 && + ++ssl->badmac_seen >= ssl->conf->badmac_limit) { + MBEDTLS_SSL_DEBUG_MSG(1, ("too many records with bad MAC")); + return MBEDTLS_ERR_SSL_INVALID_MAC; + } + + /* As above, invalid records cause + * dismissal of the whole datagram. */ + + ssl->next_record_offset = 0; + ssl->in_left = 0; + + MBEDTLS_SSL_DEBUG_MSG(1, ("discarding invalid record (mac)")); + return MBEDTLS_ERR_SSL_CONTINUE_PROCESSING; + } + + return ret; + } else +#endif + { + /* Error out (and send alert) on invalid records */ +#if defined(MBEDTLS_SSL_ALL_ALERT_MESSAGES) + if (ret == MBEDTLS_ERR_SSL_INVALID_MAC) { + mbedtls_ssl_send_alert_message(ssl, + MBEDTLS_SSL_ALERT_LEVEL_FATAL, + MBEDTLS_SSL_ALERT_MSG_BAD_RECORD_MAC); + } +#endif + return ret; + } + } + + + /* Reset in pointers to default state for TLS/DTLS records, + * assuming no CID and no offset between record content and + * record plaintext. */ + mbedtls_ssl_update_in_pointers(ssl); +#if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID) + ssl->in_len = ssl->in_cid + rec.cid_len; +#endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID */ + ssl->in_iv = ssl->in_len + 2; + + /* The record content type may change during decryption, + * so re-read it. */ + ssl->in_msgtype = rec.type; + /* Also update the input buffer, because unfortunately + * the server-side ssl_parse_client_hello() reparses the + * record header when receiving a ClientHello initiating + * a renegotiation. */ + ssl->in_hdr[0] = rec.type; + ssl->in_msg = rec.buf + rec.data_offset; + ssl->in_msglen = rec.data_len; + MBEDTLS_PUT_UINT16_BE(rec.data_len, ssl->in_len, 0); + + return 0; +} + +int mbedtls_ssl_handle_message_type(mbedtls_ssl_context *ssl) +{ + int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; + + /* + * Handle particular types of records + */ + if (ssl->in_msgtype == MBEDTLS_SSL_MSG_HANDSHAKE) { + if ((ret = mbedtls_ssl_prepare_handshake_record(ssl)) != 0) { + return ret; + } + } + + if (ssl->in_msgtype == MBEDTLS_SSL_MSG_CHANGE_CIPHER_SPEC) { + if (ssl->in_msglen != 1) { + MBEDTLS_SSL_DEBUG_MSG(1, ("invalid CCS message, len: %" MBEDTLS_PRINTF_SIZET, + ssl->in_msglen)); + return MBEDTLS_ERR_SSL_INVALID_RECORD; + } + + if (ssl->in_msg[0] != 1) { + MBEDTLS_SSL_DEBUG_MSG(1, ("invalid CCS message, content: %02x", + ssl->in_msg[0])); + return MBEDTLS_ERR_SSL_INVALID_RECORD; + } + +#if defined(MBEDTLS_SSL_PROTO_DTLS) + if (ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM && + ssl->state != MBEDTLS_SSL_CLIENT_CHANGE_CIPHER_SPEC && + ssl->state != MBEDTLS_SSL_SERVER_CHANGE_CIPHER_SPEC) { + if (ssl->handshake == NULL) { + MBEDTLS_SSL_DEBUG_MSG(1, ("dropping ChangeCipherSpec outside handshake")); + return MBEDTLS_ERR_SSL_UNEXPECTED_RECORD; + } + + MBEDTLS_SSL_DEBUG_MSG(1, ("received out-of-order ChangeCipherSpec - remember")); + return MBEDTLS_ERR_SSL_EARLY_MESSAGE; + } +#endif + +#if defined(MBEDTLS_SSL_PROTO_TLS1_3) + if (ssl->tls_version == MBEDTLS_SSL_VERSION_TLS1_3) { +#if defined(MBEDTLS_SSL_TLS1_3_COMPATIBILITY_MODE) + MBEDTLS_SSL_DEBUG_MSG(1, + ("Ignore ChangeCipherSpec in TLS 1.3 compatibility mode")); + return MBEDTLS_ERR_SSL_CONTINUE_PROCESSING; +#else + MBEDTLS_SSL_DEBUG_MSG(1, + ("ChangeCipherSpec invalid in TLS 1.3 without compatibility mode")); + return MBEDTLS_ERR_SSL_INVALID_RECORD; +#endif /* MBEDTLS_SSL_TLS1_3_COMPATIBILITY_MODE */ + } +#endif /* MBEDTLS_SSL_PROTO_TLS1_3 */ + } + + if (ssl->in_msgtype == MBEDTLS_SSL_MSG_ALERT) { + if (ssl->in_msglen != 2) { + /* Note: Standard allows for more than one 2 byte alert + to be packed in a single message, but Mbed TLS doesn't + currently support this. */ + MBEDTLS_SSL_DEBUG_MSG(1, ("invalid alert message, len: %" MBEDTLS_PRINTF_SIZET, + ssl->in_msglen)); + return MBEDTLS_ERR_SSL_INVALID_RECORD; + } + + MBEDTLS_SSL_DEBUG_MSG(2, ("got an alert message, type: [%u:%u]", + ssl->in_msg[0], ssl->in_msg[1])); + + /* + * Ignore non-fatal alerts, except close_notify and no_renegotiation + */ + if (ssl->in_msg[0] == MBEDTLS_SSL_ALERT_LEVEL_FATAL) { + MBEDTLS_SSL_DEBUG_MSG(1, ("is a fatal alert message (msg %d)", + ssl->in_msg[1])); + return MBEDTLS_ERR_SSL_FATAL_ALERT_MESSAGE; + } + + if (ssl->in_msg[0] == MBEDTLS_SSL_ALERT_LEVEL_WARNING && + ssl->in_msg[1] == MBEDTLS_SSL_ALERT_MSG_CLOSE_NOTIFY) { + MBEDTLS_SSL_DEBUG_MSG(2, ("is a close notify message")); + return MBEDTLS_ERR_SSL_PEER_CLOSE_NOTIFY; + } + +#if defined(MBEDTLS_SSL_RENEGOTIATION_ENABLED) + if (ssl->in_msg[0] == MBEDTLS_SSL_ALERT_LEVEL_WARNING && + ssl->in_msg[1] == MBEDTLS_SSL_ALERT_MSG_NO_RENEGOTIATION) { + MBEDTLS_SSL_DEBUG_MSG(2, ("is a no renegotiation alert")); + /* Will be handled when trying to parse ServerHello */ + return 0; + } +#endif + /* Silently ignore: fetch new message */ + return MBEDTLS_ERR_SSL_NON_FATAL; + } + +#if defined(MBEDTLS_SSL_PROTO_DTLS) + if (ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM) { + /* Drop unexpected ApplicationData records, + * except at the beginning of renegotiations */ + if (ssl->in_msgtype == MBEDTLS_SSL_MSG_APPLICATION_DATA && + mbedtls_ssl_is_handshake_over(ssl) == 0 +#if defined(MBEDTLS_SSL_RENEGOTIATION) + && !(ssl->renego_status == MBEDTLS_SSL_RENEGOTIATION_IN_PROGRESS && + ssl->state == MBEDTLS_SSL_SERVER_HELLO) +#endif + ) { + MBEDTLS_SSL_DEBUG_MSG(1, ("dropping unexpected ApplicationData")); + return MBEDTLS_ERR_SSL_NON_FATAL; + } + + if (ssl->handshake != NULL && + mbedtls_ssl_is_handshake_over(ssl) == 1) { + mbedtls_ssl_handshake_wrapup_free_hs_transform(ssl); + } + } +#endif /* MBEDTLS_SSL_PROTO_DTLS */ + + return 0; +} + +int mbedtls_ssl_send_fatal_handshake_failure(mbedtls_ssl_context *ssl) +{ + return mbedtls_ssl_send_alert_message(ssl, + MBEDTLS_SSL_ALERT_LEVEL_FATAL, + MBEDTLS_SSL_ALERT_MSG_HANDSHAKE_FAILURE); +} + +int mbedtls_ssl_send_alert_message(mbedtls_ssl_context *ssl, + unsigned char level, + unsigned char message) +{ + int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; + + if (ssl == NULL || ssl->conf == NULL) { + return MBEDTLS_ERR_SSL_BAD_INPUT_DATA; + } + + if (ssl->out_left != 0) { + return mbedtls_ssl_flush_output(ssl); + } + + MBEDTLS_SSL_DEBUG_MSG(2, ("=> send alert message")); + MBEDTLS_SSL_DEBUG_MSG(3, ("send alert level=%u message=%u", level, message)); + + ssl->out_msgtype = MBEDTLS_SSL_MSG_ALERT; + ssl->out_msglen = 2; + ssl->out_msg[0] = level; + ssl->out_msg[1] = message; + + if ((ret = mbedtls_ssl_write_record(ssl, SSL_FORCE_FLUSH)) != 0) { + MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_ssl_write_record", ret); + return ret; + } + MBEDTLS_SSL_DEBUG_MSG(2, ("<= send alert message")); + + return 0; +} + +int mbedtls_ssl_write_change_cipher_spec(mbedtls_ssl_context *ssl) +{ + int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; + + MBEDTLS_SSL_DEBUG_MSG(2, ("=> write change cipher spec")); + + ssl->out_msgtype = MBEDTLS_SSL_MSG_CHANGE_CIPHER_SPEC; + ssl->out_msglen = 1; + ssl->out_msg[0] = 1; + + ssl->state++; + + if ((ret = mbedtls_ssl_write_handshake_msg(ssl)) != 0) { + MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_ssl_write_handshake_msg", ret); + return ret; + } + + MBEDTLS_SSL_DEBUG_MSG(2, ("<= write change cipher spec")); + + return 0; +} + +int mbedtls_ssl_parse_change_cipher_spec(mbedtls_ssl_context *ssl) +{ + int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; + + MBEDTLS_SSL_DEBUG_MSG(2, ("=> parse change cipher spec")); + + if ((ret = mbedtls_ssl_read_record(ssl, 1)) != 0) { + MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_ssl_read_record", ret); + return ret; + } + + if (ssl->in_msgtype != MBEDTLS_SSL_MSG_CHANGE_CIPHER_SPEC) { + MBEDTLS_SSL_DEBUG_MSG(1, ("bad change cipher spec message")); + mbedtls_ssl_send_alert_message(ssl, MBEDTLS_SSL_ALERT_LEVEL_FATAL, + MBEDTLS_SSL_ALERT_MSG_UNEXPECTED_MESSAGE); + return MBEDTLS_ERR_SSL_UNEXPECTED_MESSAGE; + } + + /* CCS records are only accepted if they have length 1 and content '1', + * so we don't need to check this here. */ + + /* + * Switch to our negotiated transform and session parameters for inbound + * data. + */ + MBEDTLS_SSL_DEBUG_MSG(3, ("switching to new transform spec for inbound data")); +#if defined(MBEDTLS_SSL_PROTO_TLS1_2) + ssl->transform_in = ssl->transform_negotiate; +#endif + ssl->session_in = ssl->session_negotiate; + +#if defined(MBEDTLS_SSL_PROTO_DTLS) + if (ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM) { +#if defined(MBEDTLS_SSL_DTLS_ANTI_REPLAY) + mbedtls_ssl_dtls_replay_reset(ssl); +#endif + + /* Increment epoch */ + if (++ssl->in_epoch == 0) { + MBEDTLS_SSL_DEBUG_MSG(1, ("DTLS epoch would wrap")); + /* This is highly unlikely to happen for legitimate reasons, so + treat it as an attack and don't send an alert. */ + return MBEDTLS_ERR_SSL_COUNTER_WRAPPING; + } + } else +#endif /* MBEDTLS_SSL_PROTO_DTLS */ + memset(ssl->in_ctr, 0, MBEDTLS_SSL_SEQUENCE_NUMBER_LEN); + + mbedtls_ssl_update_in_pointers(ssl); + + ssl->state++; + + MBEDTLS_SSL_DEBUG_MSG(2, ("<= parse change cipher spec")); + + return 0; +} + +/* Once ssl->out_hdr as the address of the beginning of the + * next outgoing record is set, deduce the other pointers. + * + * Note: For TLS, we save the implicit record sequence number + * (entering MAC computation) in the 8 bytes before ssl->out_hdr, + * and the caller has to make sure there's space for this. + */ + +static size_t ssl_transform_get_explicit_iv_len( + mbedtls_ssl_transform const *transform) +{ + return transform->ivlen - transform->fixed_ivlen; +} + +void mbedtls_ssl_update_out_pointers(mbedtls_ssl_context *ssl, + mbedtls_ssl_transform *transform) +{ +#if defined(MBEDTLS_SSL_PROTO_DTLS) + if (ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM) { + ssl->out_ctr = ssl->out_hdr + 3; +#if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID) + ssl->out_cid = ssl->out_ctr + MBEDTLS_SSL_SEQUENCE_NUMBER_LEN; + ssl->out_len = ssl->out_cid; + if (transform != NULL) { + ssl->out_len += transform->out_cid_len; + } +#else /* MBEDTLS_SSL_DTLS_CONNECTION_ID */ + ssl->out_len = ssl->out_ctr + MBEDTLS_SSL_SEQUENCE_NUMBER_LEN; +#endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID */ + ssl->out_iv = ssl->out_len + 2; + } else +#endif + { + ssl->out_len = ssl->out_hdr + 3; +#if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID) + ssl->out_cid = ssl->out_len; +#endif + ssl->out_iv = ssl->out_hdr + 5; + } + + ssl->out_msg = ssl->out_iv; + /* Adjust out_msg to make space for explicit IV, if used. */ + if (transform != NULL) { + ssl->out_msg += ssl_transform_get_explicit_iv_len(transform); + } +} + +/* Once ssl->in_hdr as the address of the beginning of the + * next incoming record is set, deduce the other pointers. + * + * Note: For TLS, we save the implicit record sequence number + * (entering MAC computation) in the 8 bytes before ssl->in_hdr, + * and the caller has to make sure there's space for this. + */ + +void mbedtls_ssl_update_in_pointers(mbedtls_ssl_context *ssl) +{ + /* This function sets the pointers to match the case + * of unprotected TLS/DTLS records, with both ssl->in_iv + * and ssl->in_msg pointing to the beginning of the record + * content. + * + * When decrypting a protected record, ssl->in_msg + * will be shifted to point to the beginning of the + * record plaintext. + */ + +#if defined(MBEDTLS_SSL_PROTO_DTLS) + if (ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM) { + /* This sets the header pointers to match records + * without CID. When we receive a record containing + * a CID, the fields are shifted accordingly in + * ssl_parse_record_header(). */ + ssl->in_ctr = ssl->in_hdr + 3; +#if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID) + ssl->in_cid = ssl->in_ctr + MBEDTLS_SSL_SEQUENCE_NUMBER_LEN; + ssl->in_len = ssl->in_cid; /* Default: no CID */ +#else /* MBEDTLS_SSL_DTLS_CONNECTION_ID */ + ssl->in_len = ssl->in_ctr + MBEDTLS_SSL_SEQUENCE_NUMBER_LEN; +#endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID */ + ssl->in_iv = ssl->in_len + 2; + } else +#endif + { + ssl->in_ctr = ssl->in_hdr - MBEDTLS_SSL_SEQUENCE_NUMBER_LEN; + ssl->in_len = ssl->in_hdr + 3; +#if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID) + ssl->in_cid = ssl->in_len; +#endif + ssl->in_iv = ssl->in_hdr + 5; + } + + /* This will be adjusted at record decryption time. */ + ssl->in_msg = ssl->in_iv; +} + +/* + * Setup an SSL context + */ + +void mbedtls_ssl_reset_in_out_pointers(mbedtls_ssl_context *ssl) +{ + /* Set the incoming and outgoing record pointers. */ +#if defined(MBEDTLS_SSL_PROTO_DTLS) + if (ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM) { + ssl->out_hdr = ssl->out_buf; + ssl->in_hdr = ssl->in_buf; + } else +#endif /* MBEDTLS_SSL_PROTO_DTLS */ + { + ssl->out_ctr = ssl->out_buf; + ssl->out_hdr = ssl->out_buf + 8; + ssl->in_hdr = ssl->in_buf + 8; + } + + /* Derive other internal pointers. */ + mbedtls_ssl_update_out_pointers(ssl, NULL /* no transform enabled */); + mbedtls_ssl_update_in_pointers(ssl); +} + +/* + * SSL get accessors + */ +size_t mbedtls_ssl_get_bytes_avail(const mbedtls_ssl_context *ssl) +{ + return ssl->in_offt == NULL ? 0 : ssl->in_msglen; +} + +int mbedtls_ssl_check_pending(const mbedtls_ssl_context *ssl) +{ + /* + * Case A: We're currently holding back + * a message for further processing. + */ + + if (ssl->keep_current_message == 1) { + MBEDTLS_SSL_DEBUG_MSG(3, ("ssl_check_pending: record held back for processing")); + return 1; + } + + /* + * Case B: Further records are pending in the current datagram. + */ + +#if defined(MBEDTLS_SSL_PROTO_DTLS) + if (ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM && + ssl->in_left > ssl->next_record_offset) { + MBEDTLS_SSL_DEBUG_MSG(3, ("ssl_check_pending: more records within current datagram")); + return 1; + } +#endif /* MBEDTLS_SSL_PROTO_DTLS */ + + /* + * Case C: A handshake message is being processed. + */ + + if (ssl->in_hslen > 0 && ssl->in_hslen < ssl->in_msglen) { + MBEDTLS_SSL_DEBUG_MSG(3, + ("ssl_check_pending: more handshake messages within current record")); + return 1; + } + + /* + * Case D: An application data message is being processed + */ + if (ssl->in_offt != NULL) { + MBEDTLS_SSL_DEBUG_MSG(3, ("ssl_check_pending: application data record is being processed")); + return 1; + } + + /* + * In all other cases, the rest of the message can be dropped. + * As in ssl_get_next_record, this needs to be adapted if + * we implement support for multiple alerts in single records. + */ + + MBEDTLS_SSL_DEBUG_MSG(3, ("ssl_check_pending: nothing pending")); + return 0; +} + + +int mbedtls_ssl_get_record_expansion(const mbedtls_ssl_context *ssl) +{ + size_t transform_expansion = 0; + const mbedtls_ssl_transform *transform = ssl->transform_out; + unsigned block_size; +#if defined(MBEDTLS_USE_PSA_CRYPTO) + psa_key_attributes_t attr = PSA_KEY_ATTRIBUTES_INIT; + psa_key_type_t key_type; +#endif /* MBEDTLS_USE_PSA_CRYPTO */ + + size_t out_hdr_len = mbedtls_ssl_out_hdr_len(ssl); + + if (transform == NULL) { + return (int) out_hdr_len; + } + + +#if defined(MBEDTLS_USE_PSA_CRYPTO) + if (transform->psa_alg == PSA_ALG_GCM || + transform->psa_alg == PSA_ALG_CCM || + transform->psa_alg == PSA_ALG_AEAD_WITH_SHORTENED_TAG(PSA_ALG_CCM, 8) || + transform->psa_alg == PSA_ALG_CHACHA20_POLY1305 || + transform->psa_alg == MBEDTLS_SSL_NULL_CIPHER) { + transform_expansion = transform->minlen; + } else if (transform->psa_alg == PSA_ALG_CBC_NO_PADDING) { + (void) psa_get_key_attributes(transform->psa_key_enc, &attr); + key_type = psa_get_key_type(&attr); + + block_size = PSA_BLOCK_CIPHER_BLOCK_LENGTH(key_type); + + /* Expansion due to the addition of the MAC. */ + transform_expansion += transform->maclen; + + /* Expansion due to the addition of CBC padding; + * Theoretically up to 256 bytes, but we never use + * more than the block size of the underlying cipher. */ + transform_expansion += block_size; + + /* For TLS 1.2 or higher, an explicit IV is added + * after the record header. */ +#if defined(MBEDTLS_SSL_PROTO_TLS1_2) + transform_expansion += block_size; +#endif /* MBEDTLS_SSL_PROTO_TLS1_2 */ + } else { + MBEDTLS_SSL_DEBUG_MSG(1, + ("Unsupported psa_alg spotted in mbedtls_ssl_get_record_expansion()")); + return MBEDTLS_ERR_SSL_INTERNAL_ERROR; + } +#else + switch (mbedtls_cipher_get_cipher_mode(&transform->cipher_ctx_enc)) { + case MBEDTLS_MODE_GCM: + case MBEDTLS_MODE_CCM: + case MBEDTLS_MODE_CHACHAPOLY: + case MBEDTLS_MODE_STREAM: + transform_expansion = transform->minlen; + break; + + case MBEDTLS_MODE_CBC: + + block_size = mbedtls_cipher_get_block_size( + &transform->cipher_ctx_enc); + + /* Expansion due to the addition of the MAC. */ + transform_expansion += transform->maclen; + + /* Expansion due to the addition of CBC padding; + * Theoretically up to 256 bytes, but we never use + * more than the block size of the underlying cipher. */ + transform_expansion += block_size; + + /* For TLS 1.2 or higher, an explicit IV is added + * after the record header. */ +#if defined(MBEDTLS_SSL_PROTO_TLS1_2) + transform_expansion += block_size; +#endif /* MBEDTLS_SSL_PROTO_TLS1_2 */ + + break; + + default: + MBEDTLS_SSL_DEBUG_MSG(1, ("should never happen")); + return MBEDTLS_ERR_SSL_INTERNAL_ERROR; + } +#endif /* MBEDTLS_USE_PSA_CRYPTO */ + +#if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID) + if (transform->out_cid_len != 0) { + transform_expansion += MBEDTLS_SSL_MAX_CID_EXPANSION; + } +#endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID */ + + return (int) (out_hdr_len + transform_expansion); +} + +#if defined(MBEDTLS_SSL_RENEGOTIATION) +/* + * Check record counters and renegotiate if they're above the limit. + */ +MBEDTLS_CHECK_RETURN_CRITICAL +static int ssl_check_ctr_renegotiate(mbedtls_ssl_context *ssl) +{ + size_t ep_len = mbedtls_ssl_ep_len(ssl); + int in_ctr_cmp; + int out_ctr_cmp; + + if (mbedtls_ssl_is_handshake_over(ssl) == 0 || + ssl->renego_status == MBEDTLS_SSL_RENEGOTIATION_PENDING || + ssl->conf->disable_renegotiation == MBEDTLS_SSL_RENEGOTIATION_DISABLED) { + return 0; + } + + in_ctr_cmp = memcmp(ssl->in_ctr + ep_len, + &ssl->conf->renego_period[ep_len], + MBEDTLS_SSL_SEQUENCE_NUMBER_LEN - ep_len); + out_ctr_cmp = memcmp(&ssl->cur_out_ctr[ep_len], + &ssl->conf->renego_period[ep_len], + sizeof(ssl->cur_out_ctr) - ep_len); + + if (in_ctr_cmp <= 0 && out_ctr_cmp <= 0) { + return 0; + } + + MBEDTLS_SSL_DEBUG_MSG(1, ("record counter limit reached: renegotiate")); + return mbedtls_ssl_renegotiate(ssl); +} +#endif /* MBEDTLS_SSL_RENEGOTIATION */ + +#if defined(MBEDTLS_SSL_PROTO_TLS1_3) + +#if defined(MBEDTLS_SSL_SESSION_TICKETS) && defined(MBEDTLS_SSL_CLI_C) +MBEDTLS_CHECK_RETURN_CRITICAL +static int ssl_tls13_check_new_session_ticket(mbedtls_ssl_context *ssl) +{ + + if ((ssl->in_hslen == mbedtls_ssl_hs_hdr_len(ssl)) || + (ssl->in_msg[0] != MBEDTLS_SSL_HS_NEW_SESSION_TICKET)) { + return 0; + } + + ssl->keep_current_message = 1; + + MBEDTLS_SSL_DEBUG_MSG(3, ("NewSessionTicket received")); + mbedtls_ssl_handshake_set_state(ssl, + MBEDTLS_SSL_TLS1_3_NEW_SESSION_TICKET); + + return MBEDTLS_ERR_SSL_WANT_READ; +} +#endif /* MBEDTLS_SSL_SESSION_TICKETS && MBEDTLS_SSL_CLI_C */ + +MBEDTLS_CHECK_RETURN_CRITICAL +static int ssl_tls13_handle_hs_message_post_handshake(mbedtls_ssl_context *ssl) +{ + + MBEDTLS_SSL_DEBUG_MSG(3, ("received post-handshake message")); + +#if defined(MBEDTLS_SSL_SESSION_TICKETS) && defined(MBEDTLS_SSL_CLI_C) + if (ssl->conf->endpoint == MBEDTLS_SSL_IS_CLIENT) { + int ret = ssl_tls13_check_new_session_ticket(ssl); + if (ret != 0) { + return ret; + } + } +#endif /* MBEDTLS_SSL_SESSION_TICKETS && MBEDTLS_SSL_CLI_C */ + + /* Fail in all other cases. */ + return MBEDTLS_ERR_SSL_UNEXPECTED_MESSAGE; +} +#endif /* MBEDTLS_SSL_PROTO_TLS1_3 */ + +#if defined(MBEDTLS_SSL_PROTO_TLS1_2) +/* This function is called from mbedtls_ssl_read() when a handshake message is + * received after the initial handshake. In this context, handshake messages + * may only be sent for the purpose of initiating renegotiations. + * + * This function is introduced as a separate helper since the handling + * of post-handshake handshake messages changes significantly in TLS 1.3, + * and having a helper function allows to distinguish between TLS <= 1.2 and + * TLS 1.3 in the future without bloating the logic of mbedtls_ssl_read(). + */ +MBEDTLS_CHECK_RETURN_CRITICAL +static int ssl_tls12_handle_hs_message_post_handshake(mbedtls_ssl_context *ssl) +{ + int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; + + /* + * - For client-side, expect SERVER_HELLO_REQUEST. + * - For server-side, expect CLIENT_HELLO. + * - Fail (TLS) or silently drop record (DTLS) in other cases. + */ + +#if defined(MBEDTLS_SSL_CLI_C) + if (ssl->conf->endpoint == MBEDTLS_SSL_IS_CLIENT && + (ssl->in_msg[0] != MBEDTLS_SSL_HS_HELLO_REQUEST || + ssl->in_hslen != mbedtls_ssl_hs_hdr_len(ssl))) { + MBEDTLS_SSL_DEBUG_MSG(1, ("handshake received (not HelloRequest)")); + + /* With DTLS, drop the packet (probably from last handshake) */ +#if defined(MBEDTLS_SSL_PROTO_DTLS) + if (ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM) { + return 0; + } +#endif + return MBEDTLS_ERR_SSL_UNEXPECTED_MESSAGE; + } +#endif /* MBEDTLS_SSL_CLI_C */ + +#if defined(MBEDTLS_SSL_SRV_C) + if (ssl->conf->endpoint == MBEDTLS_SSL_IS_SERVER && + ssl->in_msg[0] != MBEDTLS_SSL_HS_CLIENT_HELLO) { + MBEDTLS_SSL_DEBUG_MSG(1, ("handshake received (not ClientHello)")); + + /* With DTLS, drop the packet (probably from last handshake) */ +#if defined(MBEDTLS_SSL_PROTO_DTLS) + if (ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM) { + return 0; + } +#endif + return MBEDTLS_ERR_SSL_UNEXPECTED_MESSAGE; + } +#endif /* MBEDTLS_SSL_SRV_C */ + +#if defined(MBEDTLS_SSL_RENEGOTIATION) + /* Determine whether renegotiation attempt should be accepted */ + if (!(ssl->conf->disable_renegotiation == MBEDTLS_SSL_RENEGOTIATION_DISABLED || + (ssl->secure_renegotiation == MBEDTLS_SSL_LEGACY_RENEGOTIATION && + ssl->conf->allow_legacy_renegotiation == + MBEDTLS_SSL_LEGACY_NO_RENEGOTIATION))) { + /* + * Accept renegotiation request + */ + + /* DTLS clients need to know renego is server-initiated */ +#if defined(MBEDTLS_SSL_PROTO_DTLS) + if (ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM && + ssl->conf->endpoint == MBEDTLS_SSL_IS_CLIENT) { + ssl->renego_status = MBEDTLS_SSL_RENEGOTIATION_PENDING; + } +#endif + ret = mbedtls_ssl_start_renegotiation(ssl); + if (ret != MBEDTLS_ERR_SSL_WAITING_SERVER_HELLO_RENEGO && + ret != 0) { + MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_ssl_start_renegotiation", + ret); + return ret; + } + } else +#endif /* MBEDTLS_SSL_RENEGOTIATION */ + { + /* + * Refuse renegotiation + */ + + MBEDTLS_SSL_DEBUG_MSG(3, ("refusing renegotiation, sending alert")); + + if ((ret = mbedtls_ssl_send_alert_message(ssl, + MBEDTLS_SSL_ALERT_LEVEL_WARNING, + MBEDTLS_SSL_ALERT_MSG_NO_RENEGOTIATION)) != 0) { + return ret; + } + } + + return 0; +} +#endif /* MBEDTLS_SSL_PROTO_TLS1_2 */ + +MBEDTLS_CHECK_RETURN_CRITICAL +static int ssl_handle_hs_message_post_handshake(mbedtls_ssl_context *ssl) +{ + /* Check protocol version and dispatch accordingly. */ +#if defined(MBEDTLS_SSL_PROTO_TLS1_3) + if (ssl->tls_version == MBEDTLS_SSL_VERSION_TLS1_3) { + return ssl_tls13_handle_hs_message_post_handshake(ssl); + } +#endif /* MBEDTLS_SSL_PROTO_TLS1_3 */ + +#if defined(MBEDTLS_SSL_PROTO_TLS1_2) + if (ssl->tls_version <= MBEDTLS_SSL_VERSION_TLS1_2) { + return ssl_tls12_handle_hs_message_post_handshake(ssl); + } +#endif /* MBEDTLS_SSL_PROTO_TLS1_2 */ + + /* Should never happen */ + return MBEDTLS_ERR_SSL_INTERNAL_ERROR; +} + +/* + * brief Read at most 'len' application data bytes from the input + * buffer. + * + * param ssl SSL context: + * - First byte of application data not read yet in the input + * buffer located at address `in_offt`. + * - The number of bytes of data not read yet is `in_msglen`. + * param buf buffer that will hold the data + * param len maximum number of bytes to read + * + * note The function updates the fields `in_offt` and `in_msglen` + * according to the number of bytes read. + * + * return The number of bytes read. + */ +static int ssl_read_application_data( + mbedtls_ssl_context *ssl, unsigned char *buf, size_t len) +{ + size_t n = (len < ssl->in_msglen) ? len : ssl->in_msglen; + + if (len != 0) { + memcpy(buf, ssl->in_offt, n); + ssl->in_msglen -= n; + } + + /* Zeroising the plaintext buffer to erase unused application data + from the memory. */ + mbedtls_platform_zeroize(ssl->in_offt, n); + + if (ssl->in_msglen == 0) { + /* all bytes consumed */ + ssl->in_offt = NULL; + ssl->keep_current_message = 0; + } else { + /* more data available */ + ssl->in_offt += n; + } + + return (int) n; +} + +/* + * Receive application data decrypted from the SSL layer + */ +int mbedtls_ssl_read(mbedtls_ssl_context *ssl, unsigned char *buf, size_t len) +{ + int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; + + if (ssl == NULL || ssl->conf == NULL) { + return MBEDTLS_ERR_SSL_BAD_INPUT_DATA; + } + + MBEDTLS_SSL_DEBUG_MSG(2, ("=> read")); + +#if defined(MBEDTLS_SSL_PROTO_DTLS) + if (ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM) { + if ((ret = mbedtls_ssl_flush_output(ssl)) != 0) { + return ret; + } + + if (ssl->handshake != NULL && + ssl->handshake->retransmit_state == MBEDTLS_SSL_RETRANS_SENDING) { + if ((ret = mbedtls_ssl_flight_transmit(ssl)) != 0) { + return ret; + } + } + } +#endif + + /* + * Check if renegotiation is necessary and/or handshake is + * in process. If yes, perform/continue, and fall through + * if an unexpected packet is received while the client + * is waiting for the ServerHello. + * + * (There is no equivalent to the last condition on + * the server-side as it is not treated as within + * a handshake while waiting for the ClientHello + * after a renegotiation request.) + */ + +#if defined(MBEDTLS_SSL_RENEGOTIATION) + ret = ssl_check_ctr_renegotiate(ssl); + if (ret != MBEDTLS_ERR_SSL_WAITING_SERVER_HELLO_RENEGO && + ret != 0) { + MBEDTLS_SSL_DEBUG_RET(1, "ssl_check_ctr_renegotiate", ret); + return ret; + } +#endif + + if (ssl->state != MBEDTLS_SSL_HANDSHAKE_OVER) { + ret = mbedtls_ssl_handshake(ssl); + if (ret != MBEDTLS_ERR_SSL_WAITING_SERVER_HELLO_RENEGO && + ret != 0) { + MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_ssl_handshake", ret); + return ret; + } + } + + /* Loop as long as no application data record is available */ + while (ssl->in_offt == NULL) { + /* Start timer if not already running */ + if (ssl->f_get_timer != NULL && + ssl->f_get_timer(ssl->p_timer) == -1) { + mbedtls_ssl_set_timer(ssl, ssl->conf->read_timeout); + } + + if ((ret = mbedtls_ssl_read_record(ssl, 1)) != 0) { + if (ret == MBEDTLS_ERR_SSL_CONN_EOF) { + return 0; + } + + MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_ssl_read_record", ret); + return ret; + } + + if (ssl->in_msglen == 0 && + ssl->in_msgtype == MBEDTLS_SSL_MSG_APPLICATION_DATA) { + /* + * OpenSSL sends empty messages to randomize the IV + */ + if ((ret = mbedtls_ssl_read_record(ssl, 1)) != 0) { + if (ret == MBEDTLS_ERR_SSL_CONN_EOF) { + return 0; + } + + MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_ssl_read_record", ret); + return ret; + } + } + + if (ssl->in_msgtype == MBEDTLS_SSL_MSG_HANDSHAKE) { + ret = ssl_handle_hs_message_post_handshake(ssl); + if (ret != 0) { + MBEDTLS_SSL_DEBUG_RET(1, "ssl_handle_hs_message_post_handshake", + ret); + return ret; + } + + /* At this point, we don't know whether the renegotiation triggered + * by the post-handshake message has been completed or not. The cases + * to consider are the following: + * 1) The renegotiation is complete. In this case, no new record + * has been read yet. + * 2) The renegotiation is incomplete because the client received + * an application data record while awaiting the ServerHello. + * 3) The renegotiation is incomplete because the client received + * a non-handshake, non-application data message while awaiting + * the ServerHello. + * + * In each of these cases, looping will be the proper action: + * - For 1), the next iteration will read a new record and check + * if it's application data. + * - For 2), the loop condition isn't satisfied as application data + * is present, hence continue is the same as break + * - For 3), the loop condition is satisfied and read_record + * will re-deliver the message that was held back by the client + * when expecting the ServerHello. + */ + + continue; + } +#if defined(MBEDTLS_SSL_RENEGOTIATION) + else if (ssl->renego_status == MBEDTLS_SSL_RENEGOTIATION_PENDING) { + if (ssl->conf->renego_max_records >= 0) { + if (++ssl->renego_records_seen > ssl->conf->renego_max_records) { + MBEDTLS_SSL_DEBUG_MSG(1, ("renegotiation requested, " + "but not honored by client")); + return MBEDTLS_ERR_SSL_UNEXPECTED_MESSAGE; + } + } + } +#endif /* MBEDTLS_SSL_RENEGOTIATION */ + + /* Fatal and closure alerts handled by mbedtls_ssl_read_record() */ + if (ssl->in_msgtype == MBEDTLS_SSL_MSG_ALERT) { + MBEDTLS_SSL_DEBUG_MSG(2, ("ignoring non-fatal non-closure alert")); + return MBEDTLS_ERR_SSL_WANT_READ; + } + + if (ssl->in_msgtype != MBEDTLS_SSL_MSG_APPLICATION_DATA) { + MBEDTLS_SSL_DEBUG_MSG(1, ("bad application data message")); + return MBEDTLS_ERR_SSL_UNEXPECTED_MESSAGE; + } + + ssl->in_offt = ssl->in_msg; + + /* We're going to return something now, cancel timer, + * except if handshake (renegotiation) is in progress */ + if (mbedtls_ssl_is_handshake_over(ssl) == 1) { + mbedtls_ssl_set_timer(ssl, 0); + } + +#if defined(MBEDTLS_SSL_PROTO_DTLS) + /* If we requested renego but received AppData, resend HelloRequest. + * Do it now, after setting in_offt, to avoid taking this branch + * again if ssl_write_hello_request() returns WANT_WRITE */ +#if defined(MBEDTLS_SSL_SRV_C) && defined(MBEDTLS_SSL_RENEGOTIATION) + if (ssl->conf->endpoint == MBEDTLS_SSL_IS_SERVER && + ssl->renego_status == MBEDTLS_SSL_RENEGOTIATION_PENDING) { + if ((ret = mbedtls_ssl_resend_hello_request(ssl)) != 0) { + MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_ssl_resend_hello_request", + ret); + return ret; + } + } +#endif /* MBEDTLS_SSL_SRV_C && MBEDTLS_SSL_RENEGOTIATION */ +#endif /* MBEDTLS_SSL_PROTO_DTLS */ + } + + ret = ssl_read_application_data(ssl, buf, len); + + MBEDTLS_SSL_DEBUG_MSG(2, ("<= read")); + + return ret; +} + +#if defined(MBEDTLS_SSL_SRV_C) && defined(MBEDTLS_SSL_EARLY_DATA) +int mbedtls_ssl_read_early_data(mbedtls_ssl_context *ssl, + unsigned char *buf, size_t len) +{ + if (ssl == NULL || (ssl->conf == NULL)) { + return MBEDTLS_ERR_SSL_BAD_INPUT_DATA; + } + + /* + * The server may receive early data only while waiting for the End of + * Early Data handshake message. + */ + if ((ssl->state != MBEDTLS_SSL_END_OF_EARLY_DATA) || + (ssl->in_offt == NULL)) { + return MBEDTLS_ERR_SSL_CANNOT_READ_EARLY_DATA; + } + + return ssl_read_application_data(ssl, buf, len); +} +#endif /* MBEDTLS_SSL_SRV_C && MBEDTLS_SSL_EARLY_DATA */ + +/* + * Send application data to be encrypted by the SSL layer, taking care of max + * fragment length and buffer size. + * + * According to RFC 5246 Section 6.2.1: + * + * Zero-length fragments of Application data MAY be sent as they are + * potentially useful as a traffic analysis countermeasure. + * + * Therefore, it is possible that the input message length is 0 and the + * corresponding return code is 0 on success. + */ +MBEDTLS_CHECK_RETURN_CRITICAL +static int ssl_write_real(mbedtls_ssl_context *ssl, + const unsigned char *buf, size_t len) +{ + int ret = mbedtls_ssl_get_max_out_record_payload(ssl); + const size_t max_len = (size_t) ret; + + if (ret < 0) { + MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_ssl_get_max_out_record_payload", ret); + return ret; + } + + if (len > max_len) { +#if defined(MBEDTLS_SSL_PROTO_DTLS) + if (ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM) { + MBEDTLS_SSL_DEBUG_MSG(1, ("fragment larger than the (negotiated) " + "maximum fragment length: %" MBEDTLS_PRINTF_SIZET + " > %" MBEDTLS_PRINTF_SIZET, + len, max_len)); + return MBEDTLS_ERR_SSL_BAD_INPUT_DATA; + } else +#endif + len = max_len; + } + + if (ssl->out_left != 0) { + /* + * The user has previously tried to send the data and + * MBEDTLS_ERR_SSL_WANT_WRITE or the message was only partially + * written. In this case, we expect the high-level write function + * (e.g. mbedtls_ssl_write()) to be called with the same parameters + */ + if ((ret = mbedtls_ssl_flush_output(ssl)) != 0) { + MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_ssl_flush_output", ret); + return ret; + } + } else { + /* + * The user is trying to send a message the first time, so we need to + * copy the data into the internal buffers and setup the data structure + * to keep track of partial writes + */ + ssl->out_msglen = len; + ssl->out_msgtype = MBEDTLS_SSL_MSG_APPLICATION_DATA; + if (len > 0) { + memcpy(ssl->out_msg, buf, len); + } + + if ((ret = mbedtls_ssl_write_record(ssl, SSL_FORCE_FLUSH)) != 0) { + MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_ssl_write_record", ret); + return ret; + } + } + + return (int) len; +} + +/* + * Write application data (public-facing wrapper) + */ +int mbedtls_ssl_write(mbedtls_ssl_context *ssl, const unsigned char *buf, size_t len) +{ + int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; + + MBEDTLS_SSL_DEBUG_MSG(2, ("=> write")); + + if (ssl == NULL || ssl->conf == NULL) { + return MBEDTLS_ERR_SSL_BAD_INPUT_DATA; + } + +#if defined(MBEDTLS_SSL_RENEGOTIATION) + if ((ret = ssl_check_ctr_renegotiate(ssl)) != 0) { + MBEDTLS_SSL_DEBUG_RET(1, "ssl_check_ctr_renegotiate", ret); + return ret; + } +#endif + + if (ssl->state != MBEDTLS_SSL_HANDSHAKE_OVER) { + if ((ret = mbedtls_ssl_handshake(ssl)) != 0) { + MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_ssl_handshake", ret); + return ret; + } + } + + ret = ssl_write_real(ssl, buf, len); + + MBEDTLS_SSL_DEBUG_MSG(2, ("<= write")); + + return ret; +} + +#if defined(MBEDTLS_SSL_EARLY_DATA) && defined(MBEDTLS_SSL_CLI_C) +int mbedtls_ssl_write_early_data(mbedtls_ssl_context *ssl, + const unsigned char *buf, size_t len) +{ + int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; + const struct mbedtls_ssl_config *conf; + uint32_t remaining; + + MBEDTLS_SSL_DEBUG_MSG(2, ("=> write early_data")); + + if (ssl == NULL || (conf = ssl->conf) == NULL) { + return MBEDTLS_ERR_SSL_BAD_INPUT_DATA; + } + + if (conf->endpoint != MBEDTLS_SSL_IS_CLIENT) { + return MBEDTLS_ERR_SSL_BAD_INPUT_DATA; + } + + if ((!mbedtls_ssl_conf_is_tls13_enabled(conf)) || + (conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM) || + (conf->early_data_enabled != MBEDTLS_SSL_EARLY_DATA_ENABLED)) { + return MBEDTLS_ERR_SSL_CANNOT_WRITE_EARLY_DATA; + } + + if (ssl->tls_version != MBEDTLS_SSL_VERSION_TLS1_3) { + return MBEDTLS_ERR_SSL_CANNOT_WRITE_EARLY_DATA; + } + + /* + * If we are at the beginning of the handshake, the early data state being + * equal to MBEDTLS_SSL_EARLY_DATA_STATE_IDLE or + * MBEDTLS_SSL_EARLY_DATA_STATE_IND_SENT advance the handshake just + * enough to be able to send early data if possible. That way, we can + * guarantee that when starting the handshake with this function we will + * send at least one record of early data. Note that when the state is + * MBEDTLS_SSL_EARLY_DATA_STATE_IND_SENT and not yet + * MBEDTLS_SSL_EARLY_DATA_STATE_CAN_WRITE, we cannot send early data + * as the early data outbound transform has not been set as we may have to + * first send a dummy CCS in clear. + */ + if ((ssl->early_data_state == MBEDTLS_SSL_EARLY_DATA_STATE_IDLE) || + (ssl->early_data_state == MBEDTLS_SSL_EARLY_DATA_STATE_IND_SENT)) { + while ((ssl->early_data_state == MBEDTLS_SSL_EARLY_DATA_STATE_IDLE) || + (ssl->early_data_state == MBEDTLS_SSL_EARLY_DATA_STATE_IND_SENT)) { + ret = mbedtls_ssl_handshake_step(ssl); + if (ret != 0) { + MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_ssl_handshake_step", ret); + return ret; + } + + ret = mbedtls_ssl_flush_output(ssl); + if (ret != 0) { + MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_ssl_flush_output", ret); + return ret; + } + } + remaining = ssl->session_negotiate->max_early_data_size; + } else { + /* + * If we are past the point where we can send early data or we have + * already reached the maximum early data size, return immediatly. + * Otherwise, progress the handshake as much as possible to not delay + * it too much. If we reach a point where we can still send early data, + * then we will send some. + */ + if ((ssl->early_data_state != MBEDTLS_SSL_EARLY_DATA_STATE_CAN_WRITE) && + (ssl->early_data_state != MBEDTLS_SSL_EARLY_DATA_STATE_ACCEPTED)) { + return MBEDTLS_ERR_SSL_CANNOT_WRITE_EARLY_DATA; + } + + remaining = ssl->session_negotiate->max_early_data_size - + ssl->total_early_data_size; + + if (remaining == 0) { + return MBEDTLS_ERR_SSL_CANNOT_WRITE_EARLY_DATA; + } + + ret = mbedtls_ssl_handshake(ssl); + if ((ret != 0) && (ret != MBEDTLS_ERR_SSL_WANT_READ)) { + MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_ssl_handshake", ret); + return ret; + } + } + + if (((ssl->early_data_state != MBEDTLS_SSL_EARLY_DATA_STATE_CAN_WRITE) && + (ssl->early_data_state != MBEDTLS_SSL_EARLY_DATA_STATE_ACCEPTED)) + || (remaining == 0)) { + return MBEDTLS_ERR_SSL_CANNOT_WRITE_EARLY_DATA; + } + + if (len > remaining) { + len = remaining; + } + + ret = ssl_write_real(ssl, buf, len); + if (ret >= 0) { + ssl->total_early_data_size += ret; + } + + MBEDTLS_SSL_DEBUG_MSG(2, ("<= write early_data, ret=%d", ret)); + + return ret; +} +#endif /* MBEDTLS_SSL_EARLY_DATA && MBEDTLS_SSL_CLI_C */ + +/* + * Notify the peer that the connection is being closed + */ +int mbedtls_ssl_close_notify(mbedtls_ssl_context *ssl) +{ + int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; + + if (ssl == NULL || ssl->conf == NULL) { + return MBEDTLS_ERR_SSL_BAD_INPUT_DATA; + } + + MBEDTLS_SSL_DEBUG_MSG(2, ("=> write close notify")); + + if (mbedtls_ssl_is_handshake_over(ssl) == 1) { + if ((ret = mbedtls_ssl_send_alert_message(ssl, + MBEDTLS_SSL_ALERT_LEVEL_WARNING, + MBEDTLS_SSL_ALERT_MSG_CLOSE_NOTIFY)) != 0) { + MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_ssl_send_alert_message", ret); + return ret; + } + } + + MBEDTLS_SSL_DEBUG_MSG(2, ("<= write close notify")); + + return 0; +} + +void mbedtls_ssl_transform_free(mbedtls_ssl_transform *transform) +{ + if (transform == NULL) { + return; + } + +#if defined(MBEDTLS_USE_PSA_CRYPTO) + psa_destroy_key(transform->psa_key_enc); + psa_destroy_key(transform->psa_key_dec); +#else + mbedtls_cipher_free(&transform->cipher_ctx_enc); + mbedtls_cipher_free(&transform->cipher_ctx_dec); +#endif /* MBEDTLS_USE_PSA_CRYPTO */ + +#if defined(MBEDTLS_SSL_SOME_SUITES_USE_MAC) +#if defined(MBEDTLS_USE_PSA_CRYPTO) + psa_destroy_key(transform->psa_mac_enc); + psa_destroy_key(transform->psa_mac_dec); +#else + mbedtls_md_free(&transform->md_ctx_enc); + mbedtls_md_free(&transform->md_ctx_dec); +#endif /* MBEDTLS_USE_PSA_CRYPTO */ +#endif + + mbedtls_platform_zeroize(transform, sizeof(mbedtls_ssl_transform)); +} + +void mbedtls_ssl_set_inbound_transform(mbedtls_ssl_context *ssl, + mbedtls_ssl_transform *transform) +{ + ssl->transform_in = transform; + memset(ssl->in_ctr, 0, MBEDTLS_SSL_SEQUENCE_NUMBER_LEN); +} + +void mbedtls_ssl_set_outbound_transform(mbedtls_ssl_context *ssl, + mbedtls_ssl_transform *transform) +{ + ssl->transform_out = transform; + memset(ssl->cur_out_ctr, 0, sizeof(ssl->cur_out_ctr)); +} + +#if defined(MBEDTLS_SSL_PROTO_DTLS) + +void mbedtls_ssl_buffering_free(mbedtls_ssl_context *ssl) +{ + unsigned offset; + mbedtls_ssl_handshake_params * const hs = ssl->handshake; + + if (hs == NULL) { + return; + } + + ssl_free_buffered_record(ssl); + + for (offset = 0; offset < MBEDTLS_SSL_MAX_BUFFERED_HS; offset++) { + ssl_buffering_free_slot(ssl, offset); + } +} + +static void ssl_buffering_free_slot(mbedtls_ssl_context *ssl, + uint8_t slot) +{ + mbedtls_ssl_handshake_params * const hs = ssl->handshake; + mbedtls_ssl_hs_buffer * const hs_buf = &hs->buffering.hs[slot]; + + if (slot >= MBEDTLS_SSL_MAX_BUFFERED_HS) { + return; + } + + if (hs_buf->is_valid == 1) { + hs->buffering.total_bytes_buffered -= hs_buf->data_len; + mbedtls_zeroize_and_free(hs_buf->data, hs_buf->data_len); + memset(hs_buf, 0, sizeof(mbedtls_ssl_hs_buffer)); + } +} + +#endif /* MBEDTLS_SSL_PROTO_DTLS */ + +/* + * Convert version numbers to/from wire format + * and, for DTLS, to/from TLS equivalent. + * + * For TLS this is the identity. + * For DTLS, map as follows, then use 1's complement (v -> ~v): + * 1.x <-> 3.x+1 for x != 0 (DTLS 1.2 based on TLS 1.2) + * DTLS 1.0 is stored as TLS 1.1 internally + */ +void mbedtls_ssl_write_version(unsigned char version[2], int transport, + mbedtls_ssl_protocol_version tls_version) +{ + uint16_t tls_version_formatted; +#if defined(MBEDTLS_SSL_PROTO_DTLS) + if (transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM) { + tls_version_formatted = + ~(tls_version - (tls_version == 0x0302 ? 0x0202 : 0x0201)); + } else +#else + ((void) transport); +#endif + { + tls_version_formatted = (uint16_t) tls_version; + } + MBEDTLS_PUT_UINT16_BE(tls_version_formatted, version, 0); +} + +uint16_t mbedtls_ssl_read_version(const unsigned char version[2], + int transport) +{ + uint16_t tls_version = MBEDTLS_GET_UINT16_BE(version, 0); +#if defined(MBEDTLS_SSL_PROTO_DTLS) + if (transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM) { + tls_version = + ~(tls_version - (tls_version == 0xfeff ? 0x0202 : 0x0201)); + } +#else + ((void) transport); +#endif + return tls_version; +} + +/* + * Send pending fatal alert. + * 0, No alert message. + * !0, if mbedtls_ssl_send_alert_message() returned in error, the error code it + * returned, ssl->alert_reason otherwise. + */ +int mbedtls_ssl_handle_pending_alert(mbedtls_ssl_context *ssl) +{ + int ret; + + /* No pending alert, return success*/ + if (ssl->send_alert == 0) { + return 0; + } + + ret = mbedtls_ssl_send_alert_message(ssl, + MBEDTLS_SSL_ALERT_LEVEL_FATAL, + ssl->alert_type); + + /* If mbedtls_ssl_send_alert_message() returned with MBEDTLS_ERR_SSL_WANT_WRITE, + * do not clear the alert to be able to send it later. + */ + if (ret != MBEDTLS_ERR_SSL_WANT_WRITE) { + ssl->send_alert = 0; + } + + if (ret != 0) { + return ret; + } + + return ssl->alert_reason; +} + +/* + * Set pending fatal alert flag. + */ +void mbedtls_ssl_pend_fatal_alert(mbedtls_ssl_context *ssl, + unsigned char alert_type, + int alert_reason) +{ + ssl->send_alert = 1; + ssl->alert_type = alert_type; + ssl->alert_reason = alert_reason; +} + +#endif /* MBEDTLS_SSL_TLS_C */ |