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pkcs7: reject signatures with internal data

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A CMS signature can have internal data, but mbedTLS does not support
verifying such signatures.  Reject them during parsing.

Signed-off-by: Demi Marie Obenour <demiobenour@gmail.com>
Signed-off-by: Dave Rodgman <dave.rodgman@arm.com>
This commit is contained in:
Demi Marie Obenour 2022-11-28 00:46:00 -05:00 committed by Dave Rodgman
parent e373a254c4
commit 6cfc469296
2 changed files with 28 additions and 28 deletions
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31
include/mbedtls/pkcs7.h
View file

@ -135,21 +135,12 @@ typedef struct mbedtls_pkcs7_signer_info {
} }
mbedtls_pkcs7_signer_info; mbedtls_pkcs7_signer_info;
/**
* Structure holding attached data as part of PKCS7 signed data format
*/
typedef struct mbedtls_pkcs7_data {
mbedtls_pkcs7_buf MBEDTLS_PRIVATE(data);
}
mbedtls_pkcs7_data;
/** /**
* Structure holding the signed data section * Structure holding the signed data section
*/ */
typedef struct mbedtls_pkcs7_signed_data { typedef struct mbedtls_pkcs7_signed_data {
int MBEDTLS_PRIVATE(version); int MBEDTLS_PRIVATE(version);
mbedtls_pkcs7_buf MBEDTLS_PRIVATE(digest_alg_identifiers); mbedtls_pkcs7_buf MBEDTLS_PRIVATE(digest_alg_identifiers);
struct mbedtls_pkcs7_data MBEDTLS_PRIVATE(content);
int MBEDTLS_PRIVATE(no_of_certs); int MBEDTLS_PRIVATE(no_of_certs);
mbedtls_x509_crt MBEDTLS_PRIVATE(certs); mbedtls_x509_crt MBEDTLS_PRIVATE(certs);
int MBEDTLS_PRIVATE(no_of_crls); int MBEDTLS_PRIVATE(no_of_crls);
@ -176,7 +167,7 @@ mbedtls_pkcs7;
void mbedtls_pkcs7_init(mbedtls_pkcs7 *pkcs7); void mbedtls_pkcs7_init(mbedtls_pkcs7 *pkcs7);
/** /**
* \brief Parse a single DER formatted pkcs7 content. * \brief Parse a single DER formatted pkcs7 detached signature.
* *
* \param pkcs7 The pkcs7 structure to be filled by parser for the output. * \param pkcs7 The pkcs7 structure to be filled by parser for the output.
* \param buf The buffer holding only the DER encoded pkcs7. * \param buf The buffer holding only the DER encoded pkcs7.
@ -186,6 +177,7 @@ void mbedtls_pkcs7_init(mbedtls_pkcs7 *pkcs7);
* \note This function makes an internal copy of the PKCS7 buffer * \note This function makes an internal copy of the PKCS7 buffer
* \p buf. In particular, \p buf may be destroyed or reused * \p buf. In particular, \p buf may be destroyed or reused
* after this call returns. * after this call returns.
* \note Signatures with internal data are not supported.
* *
* \return The \c mbedtls_pkcs7_type of \p buf, if successful. * \return The \c mbedtls_pkcs7_type of \p buf, if successful.
* \return A negative error code on failure. * \return A negative error code on failure.
@ -205,7 +197,8 @@ int mbedtls_pkcs7_parse_der(mbedtls_pkcs7 *pkcs7, const unsigned char *buf,
* matches. * matches.
* *
* This function does not use the certificates held within the * This function does not use the certificates held within the
* PKCS7 structure itself. * PKCS7 structure itself, and does not check that the
* certificate is signed by a trusted certification authority.
* *
* \param pkcs7 PKCS7 structure containing signature. * \param pkcs7 PKCS7 structure containing signature.
* \param cert Certificate containing key to verify signature. * \param cert Certificate containing key to verify signature.
@ -226,15 +219,15 @@ int mbedtls_pkcs7_signed_data_verify(mbedtls_pkcs7 *pkcs7,
* \brief Verification of PKCS7 signature against a caller-supplied * \brief Verification of PKCS7 signature against a caller-supplied
* certificate. * certificate.
* *
* For each signer in the PKCS structure, this function computes * For each signer in the PKCS structure, this function
* a signature over the supplied hash, using the supplied * validates a signature over the supplied hash, using the
* certificate and the same digest algorithm as specified by the * supplied certificate and the same digest algorithm as
* signer. It then compares this signature against the * specified by the signer. Verification succeeds if any
* signer's signature; verification succeeds if any comparison * signature is good.
* matches.
* *
* This function does not use the certificates held within the * This function does not use the certificates held within the
* PKCS7 structure itself. * PKCS7 structure itself, and does not check that the
* certificate is signed by a trusted certification authority.
* *
* \param pkcs7 PKCS7 structure containing signature. * \param pkcs7 PKCS7 structure containing signature.
* \param cert Certificate containing key to verify signature. * \param cert Certificate containing key to verify signature.
@ -242,7 +235,7 @@ int mbedtls_pkcs7_signed_data_verify(mbedtls_pkcs7 *pkcs7,
* \param hashlen Length of the hash. * \param hashlen Length of the hash.
* *
* \note This function is different from mbedtls_pkcs7_signed_data_verify() * \note This function is different from mbedtls_pkcs7_signed_data_verify()
* in a way that it directly receives the hash of the data. * in that it is directly passed the hash of the data.
* *
* \return 0 if the signature verifies, or a negative error code on failure. * \return 0 if the signature verifies, or a negative error code on failure.
*/ */

25
library/pkcs7.c
View file

@ -57,9 +57,9 @@ static int pkcs7_get_next_content_len(unsigned char **p, unsigned char *end,
ret = mbedtls_asn1_get_tag(p, end, len, MBEDTLS_ASN1_CONSTRUCTED ret = mbedtls_asn1_get_tag(p, end, len, MBEDTLS_ASN1_CONSTRUCTED
| MBEDTLS_ASN1_CONTEXT_SPECIFIC); | MBEDTLS_ASN1_CONTEXT_SPECIFIC);
if (ret != 0) { if (ret != 0) {
ret = MBEDTLS_ERROR_ADD(MBEDTLS_ERR_PKCS7_INVALID_FORMAT, ret); ret = MBEDTLS_ERROR_ADD(MBEDTLS_ERR_PKCS7_INVALID_CONTENT_INFO, ret);
} else if ((size_t) (end - *p) != *len) { } else if ((size_t) (end - *p) != *len) {
ret = MBEDTLS_ERROR_ADD(MBEDTLS_ERR_PKCS7_INVALID_FORMAT, ret = MBEDTLS_ERROR_ADD(MBEDTLS_ERR_PKCS7_INVALID_CONTENT_INFO,
MBEDTLS_ERR_ASN1_LENGTH_MISMATCH); MBEDTLS_ERR_ASN1_LENGTH_MISMATCH);
} }
@ -187,13 +187,13 @@ static int pkcs7_get_certificates(unsigned char **p, unsigned char *end,
size_t len2 = 0; size_t len2 = 0;
unsigned char *end_set, *end_cert, *start; unsigned char *end_set, *end_cert, *start;
if ((ret = mbedtls_asn1_get_tag(p, end, &len1, MBEDTLS_ASN1_CONSTRUCTED ret = mbedtls_asn1_get_tag(p, end, &len1, MBEDTLS_ASN1_CONSTRUCTED
| MBEDTLS_ASN1_CONTEXT_SPECIFIC)) != 0) { | MBEDTLS_ASN1_CONTEXT_SPECIFIC);
if (ret == MBEDTLS_ERR_ASN1_UNEXPECTED_TAG) { if (ret == MBEDTLS_ERR_ASN1_UNEXPECTED_TAG) {
return 0; return 0;
} else { }
return MBEDTLS_ERROR_ADD(MBEDTLS_ERR_PKCS7_INVALID_FORMAT, ret); if (ret != 0) {
} return MBEDTLS_ERROR_ADD(MBEDTLS_ERR_PKCS7_INVALID_FORMAT, ret);
} }
start = *p; start = *p;
end_set = *p + len1; end_set = *p + len1;
@ -716,11 +716,15 @@ static int mbedtls_pkcs7_data_or_hash_verify(mbedtls_pkcs7 *pkcs7,
return ret; return ret;
} }
int mbedtls_pkcs7_signed_data_verify(mbedtls_pkcs7 *pkcs7, int mbedtls_pkcs7_signed_data_verify(mbedtls_pkcs7 *pkcs7,
const mbedtls_x509_crt *cert, const mbedtls_x509_crt *cert,
const unsigned char *data, const unsigned char *data,
size_t datalen) size_t datalen)
{ {
if (data == NULL) {
return MBEDTLS_ERR_PKCS7_BAD_INPUT_DATA;
}
return mbedtls_pkcs7_data_or_hash_verify(pkcs7, cert, data, datalen, 0); return mbedtls_pkcs7_data_or_hash_verify(pkcs7, cert, data, datalen, 0);
} }
@ -729,6 +733,9 @@ int mbedtls_pkcs7_signed_hash_verify(mbedtls_pkcs7 *pkcs7,
const unsigned char *hash, const unsigned char *hash,
size_t hashlen) size_t hashlen)
{ {
if (hash == NULL) {
return MBEDTLS_ERR_PKCS7_BAD_INPUT_DATA;
}
return mbedtls_pkcs7_data_or_hash_verify(pkcs7, cert, hash, hashlen, 1); return mbedtls_pkcs7_data_or_hash_verify(pkcs7, cert, hash, hashlen, 1);
} }