/* * 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 "mbedtls/x509.h" #include "mbedtls/asn1write.h" #include "mbedtls/error.h" #include "mbedtls/oid.h" #include #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 = 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, c - s)) == NULL) { if ((mbedtls_oid_from_numeric_string(&oid, s, 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, 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 ((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 */