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mbedtls/library/x509_create.c
Jonathan Winzig a0c9448bea Update fix to be more platform-independent 
Co-authored-by: David Horstmann <david.horstmann@arm.com>
Signed-off-by: Jonathan Winzig <jwinzig@hilscher.com>
2024-01-22 15:31:05 +00:00

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/*
* 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 <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 */
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