coffee/mbedtls
1
0
Fork 0
mirror of https://github.com/Mbed-TLS/mbedtls.git synced 2026-11-09 14:50:17 +08:00
Code Issues Packages Projects Releases Wiki Activity

x509: complete parsing of the Name Constraints extension

Browse Source 
Parse iPAddress subtrees (address and mask, 8 or 32 bytes), which
mbedtls_x509_parse_subject_alt_name() rejects, and print them as
address/mask. Keep subtrees of name forms that can't be parsed; they
are rejected at verification time.

Follow RFC 5280 section 4.2.1.10: reject an empty NameConstraints, an
empty GeneralSubtrees, a non-zero minimum and any maximum. Check the
full tags of permittedSubtrees and excludedSubtrees, don't add the
high-level error code twice and don't leak the parsed directoryName
of a subtree.

Signed-off-by: Josef Kolář <josef.kolar@firma.seznam.cz>
This commit is contained in:
Josef Kolář 2026-10-26 14:40:49 +01:00
parent 56b265034f
commit 405c9ca1fe
No known key found for this signature in database
GPG Key ID: B63365AFDECD5329
2 changed files with 191 additions and 137 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
include/mbedtls/x509_crt.h
View File

@ -66,8 +66,8 @@ typedef struct mbedtls_x509_crt {
mbedtls_x509_buf subject_key_id; /**< Optional X.509 v3 extension subject key identifier. */
mbedtls_x509_authority authority_key_id; /**< Optional X.509 v3 extension authority key identifier. */
mbedtls_x509_sequence name_constraints_incl; /**< Optional list of raw entries of Name Constraints extension (currently only dNSName and OtherName are listed). */
mbedtls_x509_sequence name_constraints_excl; /**< Optional list of raw entries of Name Constraints extension (currently only dNSName and OtherName are listed). */
mbedtls_x509_sequence name_constraints_incl; /**< Optional list of the bases of the permittedSubtrees of the Name Constraints extension, as raw GeneralName entries like subject_alt_names. An iPAddress entry is an address followed by a mask. */
mbedtls_x509_sequence name_constraints_excl; /**< Optional list of the bases of the excludedSubtrees of the Name Constraints extension, in the same format as name_constraints_incl. */
mbedtls_x509_sequence certificate_policies; /**< Optional list of certificate policies (Only anyPolicy is printed and enforced, however the rest of the policies are still listed). */

324
library/x509_crt.c
View File

@ -586,82 +586,119 @@ static int x509_get_ext_key_usage(unsigned char **p,
}
/*
GeneralSubtrees ::= SEQUENCE SIZE (1..MAX) OF GeneralSubtree
GeneralSubtree ::= SEQUENCE {
base GeneralName,
minimum [0] BaseDistance DEFAULT 0,
maximum [1] BaseDistance OPTIONAL }
BaseDistance ::= INTEGER (0..MAX)
* Check the base of a GeneralSubtree in a Name Constraints extension.
*
* iPAddress is an address followed by a mask (8 bytes for IPv4, 32 bytes for
* IPv6), so it can't be checked with mbedtls_x509_parse_subject_alt_name().
* Name forms that mbedtls_x509_parse_subject_alt_name() doesn't support are
* accepted here: they can't be enforced, so certificates with names of such
* a form fail verification under this CA (see x509_crt_check_name_constraints()).
*/
static int x509_get_general_subtrees( unsigned char **p,
const unsigned char *end,
mbedtls_x509_sequence *general_names )
static int x509_check_general_subtree_base(const mbedtls_x509_buf *base)
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
size_t len, tag_len;
const unsigned char *item_end;
mbedtls_asn1_sequence *cur = general_names;
mbedtls_x509_subject_alternative_name name;
while( *p < end )
{
/* Sequence within the GeneralSubtree */
if( ( ret = mbedtls_asn1_get_tag( p, end, &len,
MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) ) != 0 )
return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_EXTENSIONS, ret ) );
item_end = *p + len;
if ((base->tag & MBEDTLS_ASN1_TAG_CLASS_MASK) != MBEDTLS_ASN1_CONTEXT_SPECIFIC) {
return MBEDTLS_ERROR_ADD(MBEDTLS_ERR_X509_INVALID_EXTENSIONS,
MBEDTLS_ERR_ASN1_UNEXPECTED_TAG);
}
mbedtls_x509_subject_alternative_name dummy_san_buf;
mbedtls_x509_buf tmp_san_buf;
memset(&dummy_san_buf, 0, sizeof(dummy_san_buf));
if ((base->tag & MBEDTLS_ASN1_TAG_VALUE_MASK) == MBEDTLS_X509_SAN_IP_ADDRESS) {
if (base->len != 8 && base->len != 32) {
return MBEDTLS_ERROR_ADD(MBEDTLS_ERR_X509_INVALID_EXTENSIONS,
MBEDTLS_ERR_ASN1_INVALID_LENGTH);
}
return 0;
}
tmp_san_buf.tag = **p;
(*p)++;
memset(&name, 0, sizeof(name));
ret = mbedtls_x509_parse_subject_alt_name(base, &name);
mbedtls_x509_free_subject_alt_name(&name);
if (ret == MBEDTLS_ERR_X509_FEATURE_UNAVAILABLE) {
return 0;
}
if ((ret = mbedtls_asn1_get_len(p, end, &tag_len)) != 0) {
return ret;
}
/*
* GeneralSubtrees ::= SEQUENCE SIZE (1..MAX) OF GeneralSubtree
*
* GeneralSubtree ::= SEQUENCE {
* base GeneralName,
* minimum [0] BaseDistance DEFAULT 0,
* maximum [1] BaseDistance OPTIONAL }
*
* BaseDistance ::= INTEGER (0..MAX)
*
* RFC 5280 requires minimum to be zero and maximum to be absent. DER omits a
* zero minimum, but an explicitly encoded zero is accepted too. Each base is
* stored as a raw GeneralName, like the entries of subject_alt_names.
*/
static int x509_get_general_subtrees(unsigned char **p,
const unsigned char *end,
mbedtls_x509_sequence *subtrees)
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
size_t len;
const unsigned char *subtree_end;
mbedtls_x509_buf base;
mbedtls_x509_sequence *cur = subtrees;
if (*p == end) {
return MBEDTLS_ERROR_ADD(MBEDTLS_ERR_X509_INVALID_EXTENSIONS,
MBEDTLS_ERR_ASN1_INVALID_LENGTH);
}
while (*p < end) {
if ((ret = mbedtls_asn1_get_tag(p, end, &len,
MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE)) != 0) {
return MBEDTLS_ERROR_ADD(MBEDTLS_ERR_X509_INVALID_EXTENSIONS, ret);
}
subtree_end = *p + len;
tmp_san_buf.p = *p;
tmp_san_buf.len = tag_len;
if (*p == subtree_end) {
return MBEDTLS_ERROR_ADD(MBEDTLS_ERR_X509_INVALID_EXTENSIONS,
MBEDTLS_ERR_ASN1_OUT_OF_DATA);
}
base.tag = **p;
(*p)++;
if ((ret = mbedtls_asn1_get_len(p, subtree_end, &base.len)) != 0) {
return MBEDTLS_ERROR_ADD(MBEDTLS_ERR_X509_INVALID_EXTENSIONS, ret);
}
base.p = *p;
*p += base.len;
if ((tmp_san_buf.tag & MBEDTLS_ASN1_TAG_CLASS_MASK) !=
MBEDTLS_ASN1_CONTEXT_SPECIFIC) {
if ((ret = x509_check_general_subtree_base(&base)) != 0) {
return ret;
}
/* minimum [0]: only zero is allowed */
if (*p < subtree_end && **p == MBEDTLS_ASN1_CONTEXT_SPECIFIC) {
(*p)++;
if ((ret = mbedtls_asn1_get_len(p, subtree_end, &len)) != 0) {
return MBEDTLS_ERROR_ADD(MBEDTLS_ERR_X509_INVALID_EXTENSIONS, ret);
}
if (len != 1 || **p != 0) {
return MBEDTLS_ERROR_ADD(MBEDTLS_ERR_X509_INVALID_EXTENSIONS,
MBEDTLS_ERR_ASN1_INVALID_DATA);
}
*p += len;
}
/* maximum [1] must be absent */
if (*p != subtree_end) {
return MBEDTLS_ERROR_ADD(MBEDTLS_ERR_X509_INVALID_EXTENSIONS,
MBEDTLS_ERR_ASN1_UNEXPECTED_TAG);
}
/*
* Check that the GeneralName is structured correctly.
*/
ret = mbedtls_x509_parse_subject_alt_name(&tmp_san_buf, &dummy_san_buf);
/*
* In case the extension is malformed, return an error,
* and clear the allocated sequences.
*/
if (ret != 0 && ret != MBEDTLS_ERR_X509_FEATURE_UNAVAILABLE) {
mbedtls_x509_sequence *seq_cur = general_names->next;
mbedtls_x509_sequence *seq_prv;
while (seq_cur != NULL) {
seq_prv = seq_cur;
seq_cur = seq_cur->next;
mbedtls_platform_zeroize(seq_prv,
sizeof(mbedtls_x509_sequence));
mbedtls_free(seq_prv);
}
general_names->next = NULL;
return ret;
}
/* Allocate and assign next pointer */
if (cur->buf.p != NULL) {
if (cur->next != NULL) {
return MBEDTLS_ERR_X509_INVALID_EXTENSIONS;
}
cur->next = mbedtls_calloc(1, sizeof(mbedtls_asn1_sequence));
if (cur->next == NULL) {
return MBEDTLS_ERROR_ADD(MBEDTLS_ERR_X509_INVALID_EXTENSIONS,
MBEDTLS_ERR_ASN1_ALLOC_FAILED);
@ -670,39 +707,26 @@ static int x509_get_general_subtrees( unsigned char **p,
cur = cur->next;
}
cur->buf = tmp_san_buf;
*p += tmp_san_buf.len;
// Require that minimum and maximum distance are not present
if (*p != item_end) {
return MBEDTLS_ERROR_ADD(MBEDTLS_ERR_X509_INVALID_EXTENSIONS,
MBEDTLS_ERR_ASN1_UNEXPECTED_TAG);
}
cur->buf = base;
}
/* Set final sequence entry's next pointer to NULL */
cur->next = NULL;
if( *p != end )
return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_EXTENSIONS,
MBEDTLS_ERR_ASN1_LENGTH_MISMATCH ) );
return( 0 );
return 0;
}
/*
NameConstraints ::= SEQUENCE {
permittedSubtrees [0] GeneralSubtrees OPTIONAL,
excludedSubtrees [1] GeneralSubtrees OPTIONAL }
* NameConstraints ::= SEQUENCE {
* permittedSubtrees [0] GeneralSubtrees OPTIONAL,
* excludedSubtrees [1] GeneralSubtrees OPTIONAL }
*
* RFC 5280 section 4.2.1.10: at least one of the two must be present.
*/
static int x509_get_name_constraints( unsigned char **p,
const unsigned char *end,
mbedtls_x509_sequence *include,
mbedtls_x509_sequence *exclude )
static int x509_get_name_constraints(unsigned char **p,
const unsigned char *end,
mbedtls_x509_sequence *permitted,
mbedtls_x509_sequence *excluded)
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
size_t len;
const unsigned char *end_subtree;
if ((ret = mbedtls_asn1_get_tag(p, end, &len,
MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE)) != 0) {
@ -714,59 +738,39 @@ static int x509_get_name_constraints( unsigned char **p,
MBEDTLS_ERR_ASN1_LENGTH_MISMATCH);
}
if (*p < end) {
const unsigned tag = **p;
if ((tag & MBEDTLS_ASN1_TAG_CLASS_MASK) !=
MBEDTLS_ASN1_CONTEXT_SPECIFIC) {
return MBEDTLS_ERROR_ADD(MBEDTLS_ERR_X509_INVALID_EXTENSIONS,
MBEDTLS_ERR_ASN1_UNEXPECTED_TAG);
}
if (*p == end) {
return MBEDTLS_ERROR_ADD(MBEDTLS_ERR_X509_INVALID_EXTENSIONS,
MBEDTLS_ERR_ASN1_INVALID_LENGTH);
}
/*
* permittedSubtrees
*/
if ((tag & MBEDTLS_ASN1_TAG_VALUE_MASK) == MBEDTLS_X509_NAME_CONST_INCL) {
(*p)++;
if ((ret = mbedtls_asn1_get_len(p, end, &len)) != 0) {
return MBEDTLS_ERROR_ADD(MBEDTLS_ERR_X509_INVALID_EXTENSIONS, ret);
}
end_subtree = *p + len;
if ((ret = x509_get_general_subtrees(p, end_subtree, include))) {
return MBEDTLS_ERROR_ADD(MBEDTLS_ERR_X509_INVALID_EXTENSIONS, ret);
}
ret = mbedtls_asn1_get_tag(p, end, &len,
MBEDTLS_ASN1_CONTEXT_SPECIFIC | MBEDTLS_ASN1_CONSTRUCTED |
MBEDTLS_X509_NAME_CONST_INCL);
if (ret == 0) {
if ((ret = x509_get_general_subtrees(p, *p + len, permitted)) != 0) {
return ret;
}
} else if (ret != MBEDTLS_ERR_ASN1_UNEXPECTED_TAG) {
return MBEDTLS_ERROR_ADD(MBEDTLS_ERR_X509_INVALID_EXTENSIONS, ret);
}
if (*p < end) {
const unsigned tag = **p;
if ((tag & MBEDTLS_ASN1_TAG_CLASS_MASK) !=
MBEDTLS_ASN1_CONTEXT_SPECIFIC) {
return MBEDTLS_ERROR_ADD(MBEDTLS_ERR_X509_INVALID_EXTENSIONS,
MBEDTLS_ERR_ASN1_UNEXPECTED_TAG);
if ((ret = mbedtls_asn1_get_tag(p, end, &len,
MBEDTLS_ASN1_CONTEXT_SPECIFIC | MBEDTLS_ASN1_CONSTRUCTED |
MBEDTLS_X509_NAME_CONST_EXCL)) != 0) {
return MBEDTLS_ERROR_ADD(MBEDTLS_ERR_X509_INVALID_EXTENSIONS, ret);
}
/*
* excludedSubtrees
*/
if ((tag & MBEDTLS_ASN1_TAG_VALUE_MASK) == MBEDTLS_X509_NAME_CONST_EXCL) {
(*p)++;
if ((ret = mbedtls_asn1_get_len(p, end, &len)) != 0) {
return MBEDTLS_ERROR_ADD(MBEDTLS_ERR_X509_INVALID_EXTENSIONS, ret);
}
end_subtree = *p + len;
if( (ret = x509_get_general_subtrees(p, end_subtree, exclude))) {
return MBEDTLS_ERROR_ADD(MBEDTLS_ERR_X509_INVALID_EXTENSIONS, ret);
}
if ((ret = x509_get_general_subtrees(p, *p + len, excluded)) != 0) {
return ret;
}
}
if( *p != end )
return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_EXTENSIONS,
MBEDTLS_ERR_ASN1_LENGTH_MISMATCH ) );
if (*p != end) {
return MBEDTLS_ERROR_ADD(MBEDTLS_ERR_X509_INVALID_EXTENSIONS,
MBEDTLS_ERR_ASN1_LENGTH_MISMATCH);
}
return( 0 );
return 0;
}
/*
@ -1166,10 +1170,11 @@ static int x509_get_crt_ext(unsigned char **p,
case MBEDTLS_X509_EXT_NAME_CONSTRAINTS:
/* Parse name constraints */
if ((ret = x509_get_name_constraints( p, end_ext_octet,
&crt->name_constraints_incl,
&crt->name_constraints_excl)) != 0 )
return( ret );
if ((ret = x509_get_name_constraints(p, end_ext_octet,
&crt->name_constraints_incl,
&crt->name_constraints_excl)) != 0) {
return ret;
}
break;
case MBEDTLS_X509_EXT_KEY_USAGE:
@ -1863,7 +1868,58 @@ cleanup:
return ret;
}
#endif /* MBEDTLS_FS_IO */
#endif /*
* Like mbedtls_x509_info_subject_alt_name(), but for the subtrees of a Name
* Constraints extension, where an iPAddress is an address and a mask.
*/
static int x509_info_general_subtrees(char **buf, size_t *size,
const mbedtls_x509_sequence *subtrees,
const char *prefix)
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
size_t i, half;
size_t n = *size;
char *p = *buf;
const mbedtls_x509_sequence *cur;
mbedtls_x509_sequence single;
for (cur = subtrees; cur != NULL; cur = cur->next) {
if ((cur->buf.tag & MBEDTLS_ASN1_TAG_VALUE_MASK) != MBEDTLS_X509_SAN_IP_ADDRESS) {
single.buf = cur->buf;
single.next = NULL;
if ((ret = mbedtls_x509_info_subject_alt_name(&p, &n, &single, prefix)) != 0) {
return ret;
}
continue;
}
ret = mbedtls_snprintf(p, n, "\n%s iPAddress : ", prefix);
MBEDTLS_X509_SAFE_SNPRINTF;
/* address, then mask */
half = cur->buf.len / 2;
for (i = 0; i < cur->buf.len; i++) {
if (half == 4) {
ret = mbedtls_snprintf(p, n, "%s%u",
i == 0 ? "" : i == half ? "/" : ".",
cur->buf.p[i]);
} else {
ret = mbedtls_snprintf(p, n, "%s%02X",
i == 0 ? "" : i == half ? "/" :
i % 2 == 0 ? ":" : "",
cur->buf.p[i]);
}
MBEDTLS_X509_SAFE_SNPRINTF;
}
}
*size = n;
*buf = p;
return 0;
}
/* MBEDTLS_FS_IO */
#if !defined(MBEDTLS_X509_REMOVE_INFO)
#define PRINT_ITEM(i) \
@ -2076,22 +2132,20 @@ int mbedtls_x509_crt_info(char *buf, size_t size, const char *prefix,
ret = mbedtls_snprintf(p, n, "\n%sname constraints :", prefix);
MBEDTLS_X509_SAFE_SNPRINTF;
if (crt->name_constraints_incl.buf.p) {
if (crt->name_constraints_incl.buf.p != NULL) {
ret = mbedtls_snprintf(p, n, "\n%s permitted :", prefix);
MBEDTLS_X509_SAFE_SNPRINTF;
if ((ret = mbedtls_x509_info_subject_alt_name(&p, &n,
&crt->name_constraints_incl,
prefix)) != 0) {
if ((ret = x509_info_general_subtrees(&p, &n, &crt->name_constraints_incl,
prefix)) != 0) {
return ret;
}
}
if (crt->name_constraints_excl.buf.p) {
if (crt->name_constraints_excl.buf.p != NULL) {
ret = mbedtls_snprintf(p, n, "\n%s excluded :", prefix);
MBEDTLS_X509_SAFE_SNPRINTF;
if ((ret = mbedtls_x509_info_subject_alt_name(&p, &n,
&crt->name_constraints_excl,
prefix)) != 0) {
if ((ret = x509_info_general_subtrees(&p, &n, &crt->name_constraints_excl,
prefix)) != 0) {
return ret;
}
}