diff options
Diffstat (limited to 'library/asn1write.c')
| -rw-r--r-- | library/asn1write.c | 437 |
1 files changed, 437 insertions, 0 deletions
diff --git a/library/asn1write.c b/library/asn1write.c new file mode 100644 index 00000000000..775a9ef530f --- /dev/null +++ b/library/asn1write.c @@ -0,0 +1,437 @@ +/* + * ASN.1 buffer writing functionality + * + * Copyright The Mbed TLS Contributors + * SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later + */ + +#include "common.h" + +#if defined(MBEDTLS_ASN1_WRITE_C) || defined(MBEDTLS_X509_USE_C) || \ + defined(MBEDTLS_PSA_UTIL_HAVE_ECDSA) + +#include "mbedtls/asn1write.h" +#include "mbedtls/error.h" + +#include <string.h> + +#include "mbedtls/platform.h" + +#if defined(MBEDTLS_ASN1_PARSE_C) +#include "mbedtls/asn1.h" +#endif + +int mbedtls_asn1_write_len(unsigned char **p, const unsigned char *start, size_t len) +{ +#if SIZE_MAX > 0xFFFFFFFF + if (len > 0xFFFFFFFF) { + return MBEDTLS_ERR_ASN1_INVALID_LENGTH; + } +#endif + + int required = 1; + + if (len >= 0x80) { + for (size_t l = len; l != 0; l >>= 8) { + required++; + } + } + + if (required > (*p - start)) { + return MBEDTLS_ERR_ASN1_BUF_TOO_SMALL; + } + + do { + *--(*p) = MBEDTLS_BYTE_0(len); + len >>= 8; + } while (len); + + if (required > 1) { + *--(*p) = (unsigned char) (0x80 + required - 1); + } + + return required; +} + +int mbedtls_asn1_write_tag(unsigned char **p, const unsigned char *start, unsigned char tag) +{ + if (*p - start < 1) { + return MBEDTLS_ERR_ASN1_BUF_TOO_SMALL; + } + + *--(*p) = tag; + + return 1; +} +#endif /* MBEDTLS_ASN1_WRITE_C || MBEDTLS_X509_USE_C || MBEDTLS_PSA_UTIL_HAVE_ECDSA */ + +#if defined(MBEDTLS_ASN1_WRITE_C) +static int mbedtls_asn1_write_len_and_tag(unsigned char **p, + const unsigned char *start, + size_t len, + unsigned char tag) +{ + int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; + + MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_len(p, start, len)); + MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_tag(p, start, tag)); + + return (int) len; +} + +int mbedtls_asn1_write_raw_buffer(unsigned char **p, const unsigned char *start, + const unsigned char *buf, size_t size) +{ + size_t len = 0; + + if (*p < start || (size_t) (*p - start) < size) { + return MBEDTLS_ERR_ASN1_BUF_TOO_SMALL; + } + + len = size; + (*p) -= len; + memcpy(*p, buf, len); + + return (int) len; +} + +#if defined(MBEDTLS_BIGNUM_C) +int mbedtls_asn1_write_mpi(unsigned char **p, const unsigned char *start, const mbedtls_mpi *X) +{ + int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; + size_t len = 0; + + // Write the MPI + // + len = mbedtls_mpi_size(X); + + /* DER represents 0 with a sign bit (0=nonnegative) and 7 value bits, not + * as 0 digits. We need to end up with 020100, not with 0200. */ + if (len == 0) { + len = 1; + } + + if (*p < start || (size_t) (*p - start) < len) { + return MBEDTLS_ERR_ASN1_BUF_TOO_SMALL; + } + + (*p) -= len; + MBEDTLS_MPI_CHK(mbedtls_mpi_write_binary(X, *p, len)); + + // DER format assumes 2s complement for numbers, so the leftmost bit + // should be 0 for positive numbers and 1 for negative numbers. + // + if (X->s == 1 && **p & 0x80) { + if (*p - start < 1) { + return MBEDTLS_ERR_ASN1_BUF_TOO_SMALL; + } + + *--(*p) = 0x00; + len += 1; + } + + ret = mbedtls_asn1_write_len_and_tag(p, start, len, MBEDTLS_ASN1_INTEGER); + +cleanup: + return ret; +} +#endif /* MBEDTLS_BIGNUM_C */ + +int mbedtls_asn1_write_null(unsigned char **p, const unsigned char *start) +{ + // Write NULL + // + return mbedtls_asn1_write_len_and_tag(p, start, 0, MBEDTLS_ASN1_NULL); +} + +int mbedtls_asn1_write_oid(unsigned char **p, const unsigned char *start, + const char *oid, size_t oid_len) +{ + int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; + size_t len = 0; + + MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_raw_buffer(p, start, + (const unsigned char *) oid, oid_len)); + return mbedtls_asn1_write_len_and_tag(p, start, len, MBEDTLS_ASN1_OID); +} + +int mbedtls_asn1_write_algorithm_identifier(unsigned char **p, const unsigned char *start, + const char *oid, size_t oid_len, + size_t par_len) +{ + return mbedtls_asn1_write_algorithm_identifier_ext(p, start, oid, oid_len, par_len, 1); +} + +int mbedtls_asn1_write_algorithm_identifier_ext(unsigned char **p, const unsigned char *start, + const char *oid, size_t oid_len, + size_t par_len, int has_par) +{ + int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; + size_t len = 0; + + if (has_par) { + if (par_len == 0) { + MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_null(p, start)); + } else { + len += par_len; + } + } + + MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_oid(p, start, oid, oid_len)); + + return mbedtls_asn1_write_len_and_tag(p, start, len, + MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE); +} + +int mbedtls_asn1_write_bool(unsigned char **p, const unsigned char *start, int boolean) +{ + size_t len = 0; + + if (*p - start < 1) { + return MBEDTLS_ERR_ASN1_BUF_TOO_SMALL; + } + + *--(*p) = (boolean) ? 255 : 0; + len++; + + return mbedtls_asn1_write_len_and_tag(p, start, len, MBEDTLS_ASN1_BOOLEAN); +} + +static int asn1_write_tagged_int(unsigned char **p, const unsigned char *start, int val, int tag) +{ + size_t len = 0; + + do { + if (*p - start < 1) { + return MBEDTLS_ERR_ASN1_BUF_TOO_SMALL; + } + len += 1; + *--(*p) = val & 0xff; + val >>= 8; + } while (val > 0); + + if (**p & 0x80) { + if (*p - start < 1) { + return MBEDTLS_ERR_ASN1_BUF_TOO_SMALL; + } + *--(*p) = 0x00; + len += 1; + } + + return mbedtls_asn1_write_len_and_tag(p, start, len, tag); +} + +int mbedtls_asn1_write_int(unsigned char **p, const unsigned char *start, int val) +{ + return asn1_write_tagged_int(p, start, val, MBEDTLS_ASN1_INTEGER); +} + +int mbedtls_asn1_write_enum(unsigned char **p, const unsigned char *start, int val) +{ + return asn1_write_tagged_int(p, start, val, MBEDTLS_ASN1_ENUMERATED); +} + +int mbedtls_asn1_write_tagged_string(unsigned char **p, const unsigned char *start, int tag, + const char *text, size_t text_len) +{ + int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; + size_t len = 0; + + MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_raw_buffer(p, start, + (const unsigned char *) text, + text_len)); + + return mbedtls_asn1_write_len_and_tag(p, start, len, tag); +} + +int mbedtls_asn1_write_utf8_string(unsigned char **p, const unsigned char *start, + const char *text, size_t text_len) +{ + return mbedtls_asn1_write_tagged_string(p, start, MBEDTLS_ASN1_UTF8_STRING, text, text_len); +} + +int mbedtls_asn1_write_printable_string(unsigned char **p, const unsigned char *start, + const char *text, size_t text_len) +{ + return mbedtls_asn1_write_tagged_string(p, start, MBEDTLS_ASN1_PRINTABLE_STRING, text, + text_len); +} + +int mbedtls_asn1_write_ia5_string(unsigned char **p, const unsigned char *start, + const char *text, size_t text_len) +{ + return mbedtls_asn1_write_tagged_string(p, start, MBEDTLS_ASN1_IA5_STRING, text, text_len); +} + +int mbedtls_asn1_write_named_bitstring(unsigned char **p, + const unsigned char *start, + const unsigned char *buf, + size_t bits) +{ + size_t unused_bits, byte_len; + const unsigned char *cur_byte; + unsigned char cur_byte_shifted; + unsigned char bit; + + byte_len = (bits + 7) / 8; + unused_bits = (byte_len * 8) - bits; + + /* + * Named bitstrings require that trailing 0s are excluded in the encoding + * of the bitstring. Trailing 0s are considered part of the 'unused' bits + * when encoding this value in the first content octet + */ + if (bits != 0) { + cur_byte = buf + byte_len - 1; + cur_byte_shifted = *cur_byte >> unused_bits; + + for (;;) { + bit = cur_byte_shifted & 0x1; + cur_byte_shifted >>= 1; + + if (bit != 0) { + break; + } + + bits--; + if (bits == 0) { + break; + } + + if (bits % 8 == 0) { + cur_byte_shifted = *--cur_byte; + } + } + } + + return mbedtls_asn1_write_bitstring(p, start, buf, bits); +} + +int mbedtls_asn1_write_bitstring(unsigned char **p, const unsigned char *start, + const unsigned char *buf, size_t bits) +{ + size_t len = 0; + size_t unused_bits, byte_len; + + byte_len = (bits + 7) / 8; + unused_bits = (byte_len * 8) - bits; + + if (*p < start || (size_t) (*p - start) < byte_len + 1) { + return MBEDTLS_ERR_ASN1_BUF_TOO_SMALL; + } + + len = byte_len + 1; + + /* Write the bitstring. Ensure the unused bits are zeroed */ + if (byte_len > 0) { + byte_len--; + *--(*p) = buf[byte_len] & ~((0x1 << unused_bits) - 1); + (*p) -= byte_len; + memcpy(*p, buf, byte_len); + } + + /* Write unused bits */ + *--(*p) = (unsigned char) unused_bits; + + return mbedtls_asn1_write_len_and_tag(p, start, len, MBEDTLS_ASN1_BIT_STRING); +} + +int mbedtls_asn1_write_octet_string(unsigned char **p, const unsigned char *start, + const unsigned char *buf, size_t size) +{ + int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; + size_t len = 0; + + MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_raw_buffer(p, start, buf, size)); + + return mbedtls_asn1_write_len_and_tag(p, start, len, MBEDTLS_ASN1_OCTET_STRING); +} + + +#if !defined(MBEDTLS_ASN1_PARSE_C) +/* This is a copy of the ASN.1 parsing function mbedtls_asn1_find_named_data(), + * which is replicated to avoid a dependency ASN1_WRITE_C on ASN1_PARSE_C. */ +static mbedtls_asn1_named_data *asn1_find_named_data( + mbedtls_asn1_named_data *list, + const char *oid, size_t len) +{ + while (list != NULL) { + if (list->oid.len == len && + memcmp(list->oid.p, oid, len) == 0) { + break; + } + + list = list->next; + } + + return list; +} +#else +#define asn1_find_named_data(list, oid, len) \ + ((mbedtls_asn1_named_data *) mbedtls_asn1_find_named_data(list, oid, len)) +#endif + +mbedtls_asn1_named_data *mbedtls_asn1_store_named_data( + mbedtls_asn1_named_data **head, + const char *oid, size_t oid_len, + const unsigned char *val, + size_t val_len) +{ + mbedtls_asn1_named_data *cur; + + if ((cur = asn1_find_named_data(*head, oid, oid_len)) == NULL) { + // Add new entry if not present yet based on OID + // + cur = (mbedtls_asn1_named_data *) mbedtls_calloc(1, + sizeof(mbedtls_asn1_named_data)); + if (cur == NULL) { + return NULL; + } + + cur->oid.len = oid_len; + cur->oid.p = mbedtls_calloc(1, oid_len); + if (cur->oid.p == NULL) { + mbedtls_free(cur); + return NULL; + } + + memcpy(cur->oid.p, oid, oid_len); + + cur->val.len = val_len; + if (val_len != 0) { + cur->val.p = mbedtls_calloc(1, val_len); + if (cur->val.p == NULL) { + mbedtls_free(cur->oid.p); + mbedtls_free(cur); + return NULL; + } + } + + cur->next = *head; + *head = cur; + } else if (val_len == 0) { + mbedtls_free(cur->val.p); + cur->val.p = NULL; + } else if (cur->val.len != val_len) { + /* + * Enlarge existing value buffer if needed + * Preserve old data until the allocation succeeded, to leave list in + * a consistent state in case allocation fails. + */ + void *p = mbedtls_calloc(1, val_len); + if (p == NULL) { + return NULL; + } + + mbedtls_free(cur->val.p); + cur->val.p = p; + cur->val.len = val_len; + } + + if (val != NULL && val_len != 0) { + memcpy(cur->val.p, val, val_len); + } + + return cur; +} +#endif /* MBEDTLS_ASN1_WRITE_C */ |