pkcs7: support multiple signers
Rather than only parsing/verifying one SignerInfo in the SignerInfos field of the PKCS7 stucture, allow the ability to parse and verify more than one signature. Verification will return success if any of the signatures produce a match. Signed-off-by: Daniel Axtens <dja@axtens.net> Signed-off-by: Nick Child <nick.child@ibm.com>
This commit is contained in:
Daniel Axtens
Nick Child
parent
8a10f66692
commit
3538479faa
3 changed files with 249 additions and 101 deletions
260
library/pkcs7.c
260
library/pkcs7.c
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@ -250,7 +250,6 @@ static int pkcs7_get_signature( unsigned char **p, unsigned char *end,
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}
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/**
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* SignerInfos ::= SET of SignerInfo
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* SignerInfo ::= SEQUENCE {
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* version Version;
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* issuerAndSerialNumber IssuerAndSerialNumber,
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@ -261,6 +260,88 @@ static int pkcs7_get_signature( unsigned char **p, unsigned char *end,
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* encryptedDigest EncryptedDigest,
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* unauthenticatedAttributes
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* [1] IMPLICIT Attributes OPTIONAL,
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* Returns 0 if the signerInfo is valid.
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* Return negative error code for failure.
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**/
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static int pkcs7_get_signer_info( unsigned char **p, unsigned char *end,
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mbedtls_pkcs7_signer_info *signer )
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{
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unsigned char *end_signer;
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int ret;
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size_t len = 0;
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ret = mbedtls_asn1_get_tag( p, end, &len, MBEDTLS_ASN1_CONSTRUCTED
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| MBEDTLS_ASN1_SEQUENCE );
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if( ret != 0 )
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return( MBEDTLS_ERR_PKCS7_INVALID_SIGNER_INFO + ret );
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end_signer = *p + len;
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ret = pkcs7_get_version( p, end_signer, &signer->version );
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if( ret != 0 )
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return( MBEDTLS_ERR_PKCS7_INVALID_SIGNER_INFO );
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ret = mbedtls_asn1_get_tag( p, end_signer, &len, MBEDTLS_ASN1_CONSTRUCTED
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| MBEDTLS_ASN1_SEQUENCE );
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if( ret != 0 )
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return( MBEDTLS_ERR_PKCS7_INVALID_SIGNER_INFO + ret );
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/* Parsing IssuerAndSerialNumber */
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signer->issuer_raw.p = *p;
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ret = mbedtls_asn1_get_tag( p, end_signer, &len, MBEDTLS_ASN1_CONSTRUCTED
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| MBEDTLS_ASN1_SEQUENCE );
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if( ret != 0 )
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return( MBEDTLS_ERR_PKCS7_INVALID_SIGNER_INFO + ret );
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ret = mbedtls_x509_get_name( p, *p + len, &signer->issuer );
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if( ret != 0 )
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return( MBEDTLS_ERR_PKCS7_INVALID_SIGNER_INFO );
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signer->issuer_raw.len = *p - signer->issuer_raw.p;
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ret = mbedtls_x509_get_serial( p, end_signer, &signer->serial );
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if( ret != 0 )
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return( MBEDTLS_ERR_PKCS7_INVALID_SIGNER_INFO );
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ret = pkcs7_get_digest_algorithm( p, end_signer, &signer->alg_identifier );
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if( ret != 0 )
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return( MBEDTLS_ERR_PKCS7_INVALID_SIGNER_INFO );
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ret = pkcs7_get_digest_algorithm( p, end_signer, &signer->sig_alg_identifier );
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if( ret != 0 )
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return( MBEDTLS_ERR_PKCS7_INVALID_SIGNER_INFO );
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ret = pkcs7_get_signature( p, end_signer, &signer->sig );
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if( ret != 0 )
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return( MBEDTLS_ERR_PKCS7_INVALID_SIGNER_INFO );
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/* Do not permit any unauthenticated attributes */
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if( *p != end_signer )
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return ( MBEDTLS_ERR_PKCS7_INVALID_SIGNER_INFO );
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return( 0 );
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}
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static void pkcs7_free_signer_info( mbedtls_pkcs7_signer_info *signer )
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{
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mbedtls_x509_name *name_cur;
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mbedtls_x509_name *name_prv;
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if( signer == NULL )
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return;
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name_cur = signer->issuer.next;
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while( name_cur != NULL )
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{
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name_prv = name_cur;
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name_cur = name_cur->next;
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mbedtls_free( name_prv );
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}
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}
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/**
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* SignerInfos ::= SET of SignerInfo
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* Return number of signers added to the signed data,
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* 0 or higher is valid.
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* Return negative error code for failure.
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@ -268,76 +349,61 @@ static int pkcs7_get_signature( unsigned char **p, unsigned char *end,
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static int pkcs7_get_signers_info_set( unsigned char **p, unsigned char *end,
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mbedtls_pkcs7_signer_info *signers_set )
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{
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unsigned char *end_set, *end_set_signer;
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unsigned char *end_set;
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int ret;
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int count = 0;
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size_t len = 0;
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mbedtls_pkcs7_signer_info *signer, *prev;
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ret = mbedtls_asn1_get_tag( p, end, &len, MBEDTLS_ASN1_CONSTRUCTED
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| MBEDTLS_ASN1_SET );
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if( ret != 0 )
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return( MBEDTLS_ERR_PKCS7_INVALID_SIGNER_INFO + ret );
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/* Detect zero signers */
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if( len == 0 )
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return( 0 );
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end_set = *p + len;
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ret = mbedtls_asn1_get_tag( p, end_set, &len, MBEDTLS_ASN1_CONSTRUCTED
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| MBEDTLS_ASN1_SEQUENCE );
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ret = pkcs7_get_signer_info( p, end_set, signers_set );
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if( ret != 0 )
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return( MBEDTLS_ERR_PKCS7_INVALID_SIGNER_INFO + ret );
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return( ret );
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count++;
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end_set_signer = *p + len;
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if (end_set_signer != end_set)
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return ( MBEDTLS_ERR_PKCS7_INVALID_SIGNER_INFO );
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prev = signers_set;
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while( *p != end_set )
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{
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signer = mbedtls_calloc( 1, sizeof( mbedtls_pkcs7_signer_info ) );
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if( !signer )
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{
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ret = MBEDTLS_ERR_PKCS7_ALLOC_FAILED;
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goto cleanup;
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}
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end_set = end_set_signer;
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ret = pkcs7_get_signer_info( p, end_set, signer );
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if( ret != 0 ) {
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mbedtls_free( signer );
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goto cleanup;
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}
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prev->next = signer;
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prev = signer;
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count++;
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}
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ret = pkcs7_get_version( p, end_set, &signers_set->version );
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if( ret != 0 )
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return( MBEDTLS_ERR_PKCS7_INVALID_SIGNER_INFO );
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return( count );
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ret = mbedtls_asn1_get_tag( p, end_set, &len, MBEDTLS_ASN1_CONSTRUCTED
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| MBEDTLS_ASN1_SEQUENCE );
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if( ret != 0 )
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return( MBEDTLS_ERR_PKCS7_INVALID_SIGNER_INFO + ret );
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/* Parsing IssuerAndSerialNumber */
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signers_set->issuer_raw.p = *p;
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ret = mbedtls_asn1_get_tag( p, end_set, &len, MBEDTLS_ASN1_CONSTRUCTED
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| MBEDTLS_ASN1_SEQUENCE );
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if( ret != 0 )
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return( MBEDTLS_ERR_PKCS7_INVALID_SIGNER_INFO + ret );
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ret = mbedtls_x509_get_name( p, *p + len, &signers_set->issuer );
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if( ret != 0 )
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return( MBEDTLS_ERR_PKCS7_INVALID_SIGNER_INFO );
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signers_set->issuer_raw.len = *p - signers_set->issuer_raw.p;
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ret = mbedtls_x509_get_serial( p, end_set, &signers_set->serial );
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if( ret != 0 )
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return( MBEDTLS_ERR_PKCS7_INVALID_SIGNER_INFO );
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ret = pkcs7_get_digest_algorithm( p, end_set, &signers_set->alg_identifier );
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if( ret != 0 )
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return( MBEDTLS_ERR_PKCS7_INVALID_SIGNER_INFO );
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ret = pkcs7_get_digest_algorithm( p, end_set, &signers_set->sig_alg_identifier );
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if( ret != 0 )
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return( MBEDTLS_ERR_PKCS7_INVALID_SIGNER_INFO );
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ret = pkcs7_get_signature( p, end_set, &signers_set->sig );
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if( ret != 0 )
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return( MBEDTLS_ERR_PKCS7_INVALID_SIGNER_INFO );
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signers_set->next = NULL;
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if (*p != end_set)
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return ( MBEDTLS_ERR_PKCS7_INVALID_SIGNER_INFO );
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/* Since in this version we strictly support single signer, and reaching
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* here implies we have parsed successfully, we return 1. */
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return( 1 );
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cleanup:
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signer = signers_set->next;
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pkcs7_free_signer_info( signers_set );
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while( signer )
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{
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prev = signer;
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signer = signer->next;
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pkcs7_free_signer_info( prev );
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mbedtls_free( prev );
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}
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return( ret );
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}
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/**
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@ -419,7 +485,7 @@ static int pkcs7_get_signed_data( unsigned char *buf, size_t buflen,
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signed_data->no_of_signers = ret;
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/* Support single signer */
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/* Don't permit trailing data */
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if ( p != end )
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ret = MBEDTLS_ERR_PKCS7_INVALID_FORMAT;
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@ -507,34 +573,62 @@ int mbedtls_pkcs7_signed_data_verify( mbedtls_pkcs7 *pkcs7,
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size_t datalen )
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{
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int ret;
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int ret = MBEDTLS_ERR_PKCS7_VERIFY_FAIL;
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unsigned char *hash;
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mbedtls_pk_context pk_cxt = cert->pk;
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const mbedtls_md_info_t *md_info;
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mbedtls_md_type_t md_alg;
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mbedtls_pkcs7_signer_info *signer;
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ret = mbedtls_oid_get_md_alg( &pkcs7->signed_data.digest_alg_identifiers, &md_alg );
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if( ret != 0 )
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if( pkcs7->signed_data.no_of_signers == 0 )
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return( MBEDTLS_ERR_PKCS7_VERIFY_FAIL );
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md_info = mbedtls_md_info_from_type( md_alg );
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hash = mbedtls_calloc( mbedtls_md_get_size( md_info ), 1 );
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if( hash == NULL ) {
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return( MBEDTLS_ERR_PKCS7_ALLOC_FAILED );
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}
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ret = mbedtls_md( md_info, data, datalen, hash );
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if( ret != 0 )
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/*
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* Potential TODOs
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* Currently we iterate over all signers and return success if any of them
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* verify.
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*
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* However, we could make this better by checking against the certificate's
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* identification and SignerIdentifier fields first. That would also allow
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* us to distinguish between 'no signature for key' and 'signature for key
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* failed to validate'.
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*
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* We could also cache hashes by md, so if there are several sigs all using
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* the same algo we don't recalculate the hash each time.
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*/
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signer = &pkcs7->signed_data.signers;
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while( signer )
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{
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mbedtls_free( hash );
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return( ret );
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}
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ret = mbedtls_pk_verify( &pk_cxt, md_alg, hash, 0,
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pkcs7->signed_data.signers.sig.p,
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pkcs7->signed_data.signers.sig.len );
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ret = mbedtls_oid_get_md_alg( &signer->alg_identifier, &md_alg );
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if( ret != 0 )
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return( MBEDTLS_ERR_PKCS7_VERIFY_FAIL );
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mbedtls_free( hash );
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md_info = mbedtls_md_info_from_type( md_alg );
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hash = mbedtls_calloc( mbedtls_md_get_size( md_info ), 1 );
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if( hash == NULL ) {
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return( MBEDTLS_ERR_PKCS7_ALLOC_FAILED );
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}
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ret = mbedtls_md( md_info, data, datalen, hash );
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if( ret != 0 )
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{
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mbedtls_free( hash );
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return( ret );
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}
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ret = mbedtls_pk_verify( &pk_cxt, md_alg, hash,
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mbedtls_md_get_size( md_info ),
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signer->sig.p, signer->sig.len );
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mbedtls_free( hash );
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if( ret == 0 )
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break;
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signer = signer->next;
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}
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return( ret );
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}
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@ -564,8 +658,8 @@ int mbedtls_pkcs7_signed_hash_verify( mbedtls_pkcs7 *pkcs7,
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*/
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void mbedtls_pkcs7_free( mbedtls_pkcs7 *pkcs7 )
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{
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mbedtls_x509_name *name_cur;
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mbedtls_x509_name *name_prv;
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mbedtls_pkcs7_signer_info *signer_cur;
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mbedtls_pkcs7_signer_info *signer_prev;
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if( pkcs7 == NULL || pkcs7->raw.p == NULL )
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return;
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@ -575,12 +669,14 @@ void mbedtls_pkcs7_free( mbedtls_pkcs7 *pkcs7 )
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mbedtls_x509_crt_free( &pkcs7->signed_data.certs );
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mbedtls_x509_crl_free( &pkcs7->signed_data.crl );
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name_cur = pkcs7->signed_data.signers.issuer.next;
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while( name_cur != NULL )
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signer_cur = pkcs7->signed_data.signers.next;
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pkcs7_free_signer_info( &pkcs7->signed_data.signers );
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while( signer_cur != NULL )
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{
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name_prv = name_cur;
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name_cur = name_cur->next;
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mbedtls_free( name_prv );
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signer_prev = signer_cur;
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signer_cur = signer_prev->next;
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pkcs7_free_signer_info( signer_prev );
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mbedtls_free( signer_prev );
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}
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pkcs7->raw.p = NULL;
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