diff options
Diffstat (limited to 'library/x509_create.c')
| -rw-r--r-- | library/x509_create.c | 563 |
1 files changed, 563 insertions, 0 deletions
diff --git a/library/x509_create.c b/library/x509_create.c new file mode 100644 index 00000000000..839b5df226f --- /dev/null +++ b/library/x509_create.c @@ -0,0 +1,563 @@ +/* + * X.509 base functions for creating certificates / CSRs + * + * Copyright The Mbed TLS Contributors + * SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later + */ + +#include "common.h" + +#if defined(MBEDTLS_X509_CREATE_C) + +#include "x509_internal.h" +#include "mbedtls/asn1write.h" +#include "mbedtls/error.h" +#include "mbedtls/oid.h" + +#include <string.h> + +#include "mbedtls/platform.h" + +#include "mbedtls/asn1.h" + +/* Structure linking OIDs for X.509 DN AttributeTypes to their + * string representations and default string encodings used by Mbed TLS. */ +typedef struct { + const char *name; /* String representation of AttributeType, e.g. + * "CN" or "emailAddress". */ + size_t name_len; /* Length of 'name', without trailing 0 byte. */ + const char *oid; /* String representation of OID of AttributeType, + * as per RFC 5280, Appendix A.1. encoded as per + * X.690 */ + int default_tag; /* The default character encoding used for the + * given attribute type, e.g. + * MBEDTLS_ASN1_UTF8_STRING for UTF-8. */ +} x509_attr_descriptor_t; + +#define ADD_STRLEN(s) s, sizeof(s) - 1 + +/* X.509 DN attributes from RFC 5280, Appendix A.1. */ +static const x509_attr_descriptor_t x509_attrs[] = +{ + { ADD_STRLEN("CN"), + MBEDTLS_OID_AT_CN, MBEDTLS_ASN1_UTF8_STRING }, + { ADD_STRLEN("commonName"), + MBEDTLS_OID_AT_CN, MBEDTLS_ASN1_UTF8_STRING }, + { ADD_STRLEN("C"), + MBEDTLS_OID_AT_COUNTRY, MBEDTLS_ASN1_PRINTABLE_STRING }, + { ADD_STRLEN("countryName"), + MBEDTLS_OID_AT_COUNTRY, MBEDTLS_ASN1_PRINTABLE_STRING }, + { ADD_STRLEN("O"), + MBEDTLS_OID_AT_ORGANIZATION, MBEDTLS_ASN1_UTF8_STRING }, + { ADD_STRLEN("organizationName"), + MBEDTLS_OID_AT_ORGANIZATION, MBEDTLS_ASN1_UTF8_STRING }, + { ADD_STRLEN("L"), + MBEDTLS_OID_AT_LOCALITY, MBEDTLS_ASN1_UTF8_STRING }, + { ADD_STRLEN("locality"), + MBEDTLS_OID_AT_LOCALITY, MBEDTLS_ASN1_UTF8_STRING }, + { ADD_STRLEN("R"), + MBEDTLS_OID_PKCS9_EMAIL, MBEDTLS_ASN1_IA5_STRING }, + { ADD_STRLEN("OU"), + MBEDTLS_OID_AT_ORG_UNIT, MBEDTLS_ASN1_UTF8_STRING }, + { ADD_STRLEN("organizationalUnitName"), + MBEDTLS_OID_AT_ORG_UNIT, MBEDTLS_ASN1_UTF8_STRING }, + { ADD_STRLEN("ST"), + MBEDTLS_OID_AT_STATE, MBEDTLS_ASN1_UTF8_STRING }, + { ADD_STRLEN("stateOrProvinceName"), + MBEDTLS_OID_AT_STATE, MBEDTLS_ASN1_UTF8_STRING }, + { ADD_STRLEN("emailAddress"), + MBEDTLS_OID_PKCS9_EMAIL, MBEDTLS_ASN1_IA5_STRING }, + { ADD_STRLEN("serialNumber"), + MBEDTLS_OID_AT_SERIAL_NUMBER, MBEDTLS_ASN1_PRINTABLE_STRING }, + { ADD_STRLEN("postalAddress"), + MBEDTLS_OID_AT_POSTAL_ADDRESS, MBEDTLS_ASN1_PRINTABLE_STRING }, + { ADD_STRLEN("postalCode"), + MBEDTLS_OID_AT_POSTAL_CODE, MBEDTLS_ASN1_PRINTABLE_STRING }, + { ADD_STRLEN("dnQualifier"), + MBEDTLS_OID_AT_DN_QUALIFIER, MBEDTLS_ASN1_PRINTABLE_STRING }, + { ADD_STRLEN("title"), + MBEDTLS_OID_AT_TITLE, MBEDTLS_ASN1_UTF8_STRING }, + { ADD_STRLEN("surName"), + MBEDTLS_OID_AT_SUR_NAME, MBEDTLS_ASN1_UTF8_STRING }, + { ADD_STRLEN("SN"), + MBEDTLS_OID_AT_SUR_NAME, MBEDTLS_ASN1_UTF8_STRING }, + { ADD_STRLEN("givenName"), + MBEDTLS_OID_AT_GIVEN_NAME, MBEDTLS_ASN1_UTF8_STRING }, + { ADD_STRLEN("GN"), + MBEDTLS_OID_AT_GIVEN_NAME, MBEDTLS_ASN1_UTF8_STRING }, + { ADD_STRLEN("initials"), + MBEDTLS_OID_AT_INITIALS, MBEDTLS_ASN1_UTF8_STRING }, + { ADD_STRLEN("pseudonym"), + MBEDTLS_OID_AT_PSEUDONYM, MBEDTLS_ASN1_UTF8_STRING }, + { ADD_STRLEN("generationQualifier"), + MBEDTLS_OID_AT_GENERATION_QUALIFIER, MBEDTLS_ASN1_UTF8_STRING }, + { ADD_STRLEN("domainComponent"), + MBEDTLS_OID_DOMAIN_COMPONENT, MBEDTLS_ASN1_IA5_STRING }, + { ADD_STRLEN("DC"), + MBEDTLS_OID_DOMAIN_COMPONENT, MBEDTLS_ASN1_IA5_STRING }, + { NULL, 0, NULL, MBEDTLS_ASN1_NULL } +}; + +static const x509_attr_descriptor_t *x509_attr_descr_from_name(const char *name, size_t name_len) +{ + const x509_attr_descriptor_t *cur; + + for (cur = x509_attrs; cur->name != NULL; cur++) { + if (cur->name_len == name_len && + strncmp(cur->name, name, name_len) == 0) { + break; + } + } + + if (cur->name == NULL) { + return NULL; + } + + return cur; +} + +static int hex_to_int(char c) +{ + return ('0' <= c && c <= '9') ? (c - '0') : + ('a' <= c && c <= 'f') ? (c - 'a' + 10) : + ('A' <= c && c <= 'F') ? (c - 'A' + 10) : -1; +} + +static int hexpair_to_int(const char *hexpair) +{ + int n1 = hex_to_int(*hexpair); + int n2 = hex_to_int(*(hexpair + 1)); + + if (n1 != -1 && n2 != -1) { + return (n1 << 4) | n2; + } else { + return -1; + } +} + +static int parse_attribute_value_string(const char *s, + int len, + unsigned char *data, + size_t *data_len) +{ + const char *c; + const char *end = s + len; + unsigned char *d = data; + int n; + + for (c = s; c < end; c++) { + if (*c == '\\') { + c++; + + /* Check for valid escaped characters as per RFC 4514 Section 3 */ + if (c + 1 < end && (n = hexpair_to_int(c)) != -1) { + if (n == 0) { + return MBEDTLS_ERR_X509_INVALID_NAME; + } + *(d++) = n; + c++; + } else if (c < end && strchr(" ,=+<>#;\"\\", *c)) { + *(d++) = *c; + } else { + return MBEDTLS_ERR_X509_INVALID_NAME; + } + } else { + *(d++) = *c; + } + + if (d - data == MBEDTLS_X509_MAX_DN_NAME_SIZE) { + return MBEDTLS_ERR_X509_INVALID_NAME; + } + } + *data_len = (size_t) (d - data); + return 0; +} + +/** Parse a hexstring containing a DER-encoded string. + * + * \param s A string of \p len bytes hexadecimal digits. + * \param len Number of bytes to read from \p s. + * \param data Output buffer of size \p data_size. + * On success, it contains the payload that's DER-encoded + * in the input (content without the tag and length). + * If the DER tag is a string tag, the payload is guaranteed + * not to contain null bytes. + * \param data_size Length of the \p data buffer. + * \param data_len On success, the length of the parsed string. + * It is guaranteed to be less than + * #MBEDTLS_X509_MAX_DN_NAME_SIZE. + * \param tag The ASN.1 tag that the payload in \p data is encoded in. + * + * \retval 0 on success. + * \retval #MBEDTLS_ERR_X509_INVALID_NAME if \p s does not contain + * a valid hexstring, + * or if the decoded hexstring is not valid DER, + * or if the payload does not fit in \p data, + * or if the payload is more than + * #MBEDTLS_X509_MAX_DN_NAME_SIZE bytes, + * of if \p *tag is an ASN.1 string tag and the payload + * contains a null byte. + * \retval #MBEDTLS_ERR_X509_ALLOC_FAILED on low memory. + */ +static int parse_attribute_value_hex_der_encoded(const char *s, + size_t len, + unsigned char *data, + size_t data_size, + size_t *data_len, + int *tag) +{ + /* Step 1: preliminary length checks. */ + /* Each byte is encoded by exactly two hexadecimal digits. */ + if (len % 2 != 0) { + /* Odd number of hex digits */ + return MBEDTLS_ERR_X509_INVALID_NAME; + } + size_t const der_length = len / 2; + if (der_length > MBEDTLS_X509_MAX_DN_NAME_SIZE + 4) { + /* The payload would be more than MBEDTLS_X509_MAX_DN_NAME_SIZE + * (after subtracting the ASN.1 tag and length). Reject this early + * to avoid allocating a large intermediate buffer. */ + return MBEDTLS_ERR_X509_INVALID_NAME; + } + if (der_length < 1) { + /* Avoid empty-buffer shenanigans. A valid DER encoding is never + * empty. */ + return MBEDTLS_ERR_X509_INVALID_NAME; + } + + /* Step 2: Decode the hex string into an intermediate buffer. */ + unsigned char *der = mbedtls_calloc(1, der_length); + if (der == NULL) { + return MBEDTLS_ERR_X509_ALLOC_FAILED; + } + /* Beyond this point, der needs to be freed on exit. */ + for (size_t i = 0; i < der_length; i++) { + int c = hexpair_to_int(s + 2 * i); + if (c < 0) { + goto error; + } + der[i] = c; + } + + /* Step 3: decode the DER. */ + /* We've checked that der_length >= 1 above. */ + *tag = der[0]; + { + unsigned char *p = der + 1; + if (mbedtls_asn1_get_len(&p, der + der_length, data_len) != 0) { + goto error; + } + /* Now p points to the first byte of the payload inside der, + * and *data_len is the length of the payload. */ + + /* Step 4: payload validation */ + if (*data_len > MBEDTLS_X509_MAX_DN_NAME_SIZE) { + goto error; + } + /* Strings must not contain null bytes. */ + if (MBEDTLS_ASN1_IS_STRING_TAG(*tag)) { + for (size_t i = 0; i < *data_len; i++) { + if (p[i] == 0) { + goto error; + } + } + } + + /* Step 5: output the payload. */ + if (*data_len > data_size) { + goto error; + } + memcpy(data, p, *data_len); + } + mbedtls_free(der); + + return 0; + +error: + mbedtls_free(der); + return MBEDTLS_ERR_X509_INVALID_NAME; +} + +int mbedtls_x509_string_to_names(mbedtls_asn1_named_data **head, const char *name) +{ + int ret = MBEDTLS_ERR_X509_INVALID_NAME; + int parse_ret = 0; + const char *s = name, *c = s; + const char *end = s + strlen(s); + mbedtls_asn1_buf oid = { .p = NULL, .len = 0, .tag = MBEDTLS_ASN1_NULL }; + const x509_attr_descriptor_t *attr_descr = NULL; + int in_attr_type = 1; + int tag; + int numericoid = 0; + unsigned char data[MBEDTLS_X509_MAX_DN_NAME_SIZE]; + size_t data_len = 0; + + /* Clear existing chain if present */ + mbedtls_asn1_free_named_data_list(head); + + while (c <= end) { + if (in_attr_type && *c == '=') { + if ((attr_descr = x509_attr_descr_from_name(s, (size_t) (c - s))) == NULL) { + if ((mbedtls_oid_from_numeric_string(&oid, s, (size_t) (c - s))) != 0) { + return MBEDTLS_ERR_X509_INVALID_NAME; + } else { + numericoid = 1; + } + } else { + oid.len = strlen(attr_descr->oid); + oid.p = mbedtls_calloc(1, oid.len); + memcpy(oid.p, attr_descr->oid, oid.len); + numericoid = 0; + } + + s = c + 1; + in_attr_type = 0; + } + + if (!in_attr_type && ((*c == ',' && *(c-1) != '\\') || c == end)) { + if (s == c) { + mbedtls_free(oid.p); + return MBEDTLS_ERR_X509_INVALID_NAME; + } else if (*s == '#') { + /* We know that c >= s (loop invariant) and c != s (in this + * else branch), hence c - s - 1 >= 0. */ + parse_ret = parse_attribute_value_hex_der_encoded( + s + 1, (size_t) (c - s) - 1, + data, sizeof(data), &data_len, &tag); + if (parse_ret != 0) { + mbedtls_free(oid.p); + return parse_ret; + } + } else { + if (numericoid) { + mbedtls_free(oid.p); + return MBEDTLS_ERR_X509_INVALID_NAME; + } else { + if ((parse_ret = + parse_attribute_value_string(s, (int) (c - s), data, + &data_len)) != 0) { + mbedtls_free(oid.p); + return parse_ret; + } + tag = attr_descr->default_tag; + } + } + + mbedtls_asn1_named_data *cur = + mbedtls_asn1_store_named_data(head, (char *) oid.p, oid.len, + (unsigned char *) data, + data_len); + mbedtls_free(oid.p); + oid.p = NULL; + if (cur == NULL) { + return MBEDTLS_ERR_X509_ALLOC_FAILED; + } + + // set tagType + cur->val.tag = tag; + + while (c < end && *(c + 1) == ' ') { + c++; + } + + s = c + 1; + in_attr_type = 1; + + /* Successfully parsed one name, update ret to success */ + ret = 0; + } + c++; + } + if (oid.p != NULL) { + mbedtls_free(oid.p); + } + return ret; +} + +/* The first byte of the value in the mbedtls_asn1_named_data structure is reserved + * to store the critical boolean for us + */ +int mbedtls_x509_set_extension(mbedtls_asn1_named_data **head, const char *oid, size_t oid_len, + int critical, const unsigned char *val, size_t val_len) +{ + mbedtls_asn1_named_data *cur; + + if (val_len > (SIZE_MAX - 1)) { + return MBEDTLS_ERR_X509_BAD_INPUT_DATA; + } + + if ((cur = mbedtls_asn1_store_named_data(head, oid, oid_len, + NULL, val_len + 1)) == NULL) { + return MBEDTLS_ERR_X509_ALLOC_FAILED; + } + + cur->val.p[0] = critical; + memcpy(cur->val.p + 1, val, val_len); + + return 0; +} + +/* + * RelativeDistinguishedName ::= + * SET OF AttributeTypeAndValue + * + * AttributeTypeAndValue ::= SEQUENCE { + * type AttributeType, + * value AttributeValue } + * + * AttributeType ::= OBJECT IDENTIFIER + * + * AttributeValue ::= ANY DEFINED BY AttributeType + */ +static int x509_write_name(unsigned char **p, + unsigned char *start, + mbedtls_asn1_named_data *cur_name) +{ + int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; + size_t len = 0; + const char *oid = (const char *) cur_name->oid.p; + size_t oid_len = cur_name->oid.len; + const unsigned char *name = cur_name->val.p; + size_t name_len = cur_name->val.len; + + // Write correct string tag and value + MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_tagged_string(p, start, + cur_name->val.tag, + (const char *) name, + name_len)); + // Write OID + // + MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_oid(p, start, oid, + oid_len)); + + MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_len(p, start, len)); + MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_tag(p, start, + MBEDTLS_ASN1_CONSTRUCTED | + MBEDTLS_ASN1_SEQUENCE)); + + MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_len(p, start, len)); + MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_tag(p, start, + MBEDTLS_ASN1_CONSTRUCTED | + MBEDTLS_ASN1_SET)); + + return (int) len; +} + +int mbedtls_x509_write_names(unsigned char **p, unsigned char *start, + mbedtls_asn1_named_data *first) +{ + int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; + size_t len = 0; + mbedtls_asn1_named_data *cur = first; + + while (cur != NULL) { + MBEDTLS_ASN1_CHK_ADD(len, x509_write_name(p, start, cur)); + cur = cur->next; + } + + MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_len(p, start, len)); + MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_tag(p, start, MBEDTLS_ASN1_CONSTRUCTED | + MBEDTLS_ASN1_SEQUENCE)); + + return (int) len; +} + +int mbedtls_x509_write_sig(unsigned char **p, unsigned char *start, + const char *oid, size_t oid_len, + unsigned char *sig, size_t size, + mbedtls_pk_type_t pk_alg) +{ + int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; + int write_null_par; + 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, sig, len); + + if (*p - start < 1) { + return MBEDTLS_ERR_ASN1_BUF_TOO_SMALL; + } + + *--(*p) = 0; + len += 1; + + MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_len(p, start, len)); + MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_tag(p, start, MBEDTLS_ASN1_BIT_STRING)); + + // Write OID + // + if (pk_alg == MBEDTLS_PK_ECDSA) { + /* + * The AlgorithmIdentifier's parameters field must be absent for DSA/ECDSA signature + * algorithms, see https://www.rfc-editor.org/rfc/rfc5480#page-17 and + * https://www.rfc-editor.org/rfc/rfc5758#section-3. + */ + write_null_par = 0; + } else { + write_null_par = 1; + } + MBEDTLS_ASN1_CHK_ADD(len, + mbedtls_asn1_write_algorithm_identifier_ext(p, start, oid, oid_len, + 0, write_null_par)); + + return (int) len; +} + +static int x509_write_extension(unsigned char **p, unsigned char *start, + mbedtls_asn1_named_data *ext) +{ + int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; + size_t len = 0; + + MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_raw_buffer(p, start, ext->val.p + 1, + ext->val.len - 1)); + MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_len(p, start, ext->val.len - 1)); + MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_tag(p, start, MBEDTLS_ASN1_OCTET_STRING)); + + if (ext->val.p[0] != 0) { + MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_bool(p, start, 1)); + } + + MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_raw_buffer(p, start, ext->oid.p, + ext->oid.len)); + MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_len(p, start, ext->oid.len)); + MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_tag(p, start, MBEDTLS_ASN1_OID)); + + MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_len(p, start, len)); + MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_tag(p, start, MBEDTLS_ASN1_CONSTRUCTED | + MBEDTLS_ASN1_SEQUENCE)); + + return (int) len; +} + +/* + * Extension ::= SEQUENCE { + * extnID OBJECT IDENTIFIER, + * critical BOOLEAN DEFAULT FALSE, + * extnValue OCTET STRING + * -- contains the DER encoding of an ASN.1 value + * -- corresponding to the extension type identified + * -- by extnID + * } + */ +int mbedtls_x509_write_extensions(unsigned char **p, unsigned char *start, + mbedtls_asn1_named_data *first) +{ + int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; + size_t len = 0; + mbedtls_asn1_named_data *cur_ext = first; + + while (cur_ext != NULL) { + MBEDTLS_ASN1_CHK_ADD(len, x509_write_extension(p, start, cur_ext)); + cur_ext = cur_ext->next; + } + + return (int) len; +} + +#endif /* MBEDTLS_X509_CREATE_C */ |