Unify parsing of the signature algorithms extension
Signed-off-by: Gabor Mezei <gabor.mezei@arm.com>
diff --git a/library/ssl_tls12_server.c b/library/ssl_tls12_server.c
index a1505d1..82b6e3a 100644
--- a/library/ssl_tls12_server.c
+++ b/library/ssl_tls12_server.c
@@ -209,96 +209,6 @@
return( 0 );
}
-#if defined(MBEDTLS_KEY_EXCHANGE_WITH_CERT_ENABLED)
-
-/*
- * Status of the implementation of signature-algorithms extension:
- *
- * Currently, we are only considering the signature-algorithm extension
- * to pick a ciphersuite which allows us to send the ServerKeyExchange
- * message with a signature-hash combination that the user allows.
- *
- * We do *not* check whether all certificates in our certificate
- * chain are signed with an allowed signature-hash pair.
- * This needs to be done at a later stage.
- *
- */
-static int ssl_parse_sig_alg_ext( mbedtls_ssl_context *ssl,
- const unsigned char *buf,
- size_t len )
-{
- size_t sig_alg_list_size;
-
- const unsigned char *p;
- const unsigned char *end = buf + len;
-
- mbedtls_md_type_t md_cur;
- mbedtls_pk_type_t sig_cur;
-
- if ( len < 2 ) {
- MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad client hello message" ) );
- mbedtls_ssl_send_alert_message( ssl, MBEDTLS_SSL_ALERT_LEVEL_FATAL,
- MBEDTLS_SSL_ALERT_MSG_DECODE_ERROR );
- return( MBEDTLS_ERR_SSL_DECODE_ERROR );
- }
- sig_alg_list_size = ( ( buf[0] << 8 ) | ( buf[1] ) );
- if( sig_alg_list_size + 2 != len ||
- sig_alg_list_size % 2 != 0 )
- {
- MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad client hello message" ) );
- mbedtls_ssl_send_alert_message( ssl, MBEDTLS_SSL_ALERT_LEVEL_FATAL,
- MBEDTLS_SSL_ALERT_MSG_DECODE_ERROR );
- return( MBEDTLS_ERR_SSL_DECODE_ERROR );
- }
-
- /* Currently we only guarantee signing the ServerKeyExchange message according
- * to the constraints specified in this extension (see above), so it suffices
- * to remember only one suitable hash for each possible signature algorithm.
- *
- * This will change when we also consider certificate signatures,
- * in which case we will need to remember the whole signature-hash
- * pair list from the extension.
- */
-
- for( p = buf + 2; p < end; p += 2 )
- {
- /* Silently ignore unknown signature or hash algorithms. */
-
- if( ( sig_cur = mbedtls_ssl_pk_alg_from_sig( p[1] ) ) == MBEDTLS_PK_NONE )
- {
- MBEDTLS_SSL_DEBUG_MSG( 3, ( "client hello v3, signature_algorithm ext"
- " unknown sig alg encoding %d", p[1] ) );
- continue;
- }
-
- /* Check if we support the hash the user proposes */
- md_cur = mbedtls_ssl_md_alg_from_hash( p[0] );
- if( md_cur == MBEDTLS_MD_NONE )
- {
- MBEDTLS_SSL_DEBUG_MSG( 3, ( "client hello v3, signature_algorithm ext:"
- " unknown hash alg encoding %d", p[0] ) );
- continue;
- }
-
- if( mbedtls_ssl_sig_alg_is_offered(
- ssl, MBEDTLS_GET_UINT16_BE( p, 0 ) ) )
- {
- mbedtls_ssl_sig_hash_set_add( &ssl->handshake->hash_algs, sig_cur, md_cur );
- MBEDTLS_SSL_DEBUG_MSG( 3, ( "client hello v3, signature_algorithm ext:"
- " match sig %u and hash %u",
- (unsigned) sig_cur, (unsigned) md_cur ) );
- }
- else
- {
- MBEDTLS_SSL_DEBUG_MSG( 3, ( "client hello v3, signature_algorithm ext: "
- "hash alg %u not supported", (unsigned) md_cur ) );
- }
- }
-
- return( 0 );
-}
-#endif /* MBEDTLS_KEY_EXCHANGE_WITH_CERT_ENABLED */
-
#if defined(MBEDTLS_ECDH_C) || defined(MBEDTLS_ECDSA_C) || \
defined(MBEDTLS_KEY_EXCHANGE_ECJPAKE_ENABLED)
/*
@@ -1078,7 +988,7 @@
* a suitable hash algorithm is present. */
sig_type = mbedtls_ssl_get_ciphersuite_sig_alg( suite_info );
if( sig_type != MBEDTLS_PK_NONE &&
- mbedtls_ssl_sig_hash_set_find( &ssl->handshake->hash_algs, sig_type ) == MBEDTLS_MD_NONE )
+ mbedtls_ssl_sig_hash_set_find( ssl, sig_type ) == MBEDTLS_MD_NONE )
{
MBEDTLS_SSL_DEBUG_MSG( 3, ( "ciphersuite mismatch: no suitable hash algorithm "
"for signature algorithm %u", (unsigned) sig_type ) );
@@ -1593,7 +1503,7 @@
case MBEDTLS_TLS_EXT_SIG_ALG:
MBEDTLS_SSL_DEBUG_MSG( 3, ( "found signature_algorithms extension" ) );
- ret = ssl_parse_sig_alg_ext( ssl, ext + 4, ext_size );
+ ret = mbedtls_ssl_parse_sig_alg_ext( ssl, ext + 4, ext + 4 + ext_size );
if( ret != 0 )
return( ret );
@@ -1719,16 +1629,26 @@
*/
if( sig_hash_alg_ext_present == 0 )
{
- uint16_t sig_algs[] = { MBEDTLS_SSL_SIG_ALG(MBEDTLS_SSL_HASH_SHA1) };
- mbedtls_md_type_t md_default = MBEDTLS_MD_NONE;
- for( i = 0; i < sizeof( sig_algs ) / sizeof( sig_algs[0] ) ; i++ )
- {
- if( mbedtls_ssl_sig_alg_is_offered( ssl, sig_algs[ i ] ) )
- md_default = MBEDTLS_MD_SHA1;
- }
+ uint16_t *set = ssl->handshake->received_sig_algs;
+ const uint16_t sig_algs[] = {
+ MBEDTLS_SSL_SIG_ALG_SET( MBEDTLS_SSL_HASH_SHA1 )
+ MBEDTLS_SSL_SIG_ALG( MBEDTLS_SSL_SIG_ANON, MBEDTLS_SSL_HASH_NONE )
+ };
+ size_t count = sizeof( sig_algs ) / sizeof( sig_algs[0] );
- mbedtls_ssl_sig_hash_set_const_hash( &ssl->handshake->hash_algs,
- md_default );
+ if( count <= MBEDTLS_RECEIVED_SIG_ALGS_SIZE )
+ {
+ memcpy( set, sig_algs, sizeof( sig_algs ) );
+ }
+ else
+ {
+ size_t size = ( MBEDTLS_RECEIVED_SIG_ALGS_SIZE - 1 ) *
+ sizeof( sig_algs[0] );
+
+ memcpy( set, sig_algs, size );
+ memcpy( &set[MBEDTLS_RECEIVED_SIG_ALGS_SIZE - 1],
+ &sig_algs[count - 1], sizeof( sig_algs[0] ) );
+ }
}
#endif /* MBEDTLS_KEY_EXCHANGE_WITH_CERT_ENABLED */
@@ -1889,8 +1809,7 @@
mbedtls_pk_type_t sig_alg = mbedtls_ssl_get_ciphersuite_sig_alg( ciphersuite_info );
if( sig_alg != MBEDTLS_PK_NONE )
{
- mbedtls_md_type_t md_alg = mbedtls_ssl_sig_hash_set_find( &ssl->handshake->hash_algs,
- sig_alg );
+ mbedtls_md_type_t md_alg = mbedtls_ssl_sig_hash_set_find( ssl, sig_alg );
MBEDTLS_SSL_DEBUG_MSG( 3, ( "client hello v3, signature_algorithm ext: %d",
mbedtls_ssl_hash_from_md_alg( md_alg ) ) );
}
@@ -3262,8 +3181,7 @@
/* For TLS 1.2, obey signature-hash-algorithm extension
* (RFC 5246, Sec. 7.4.1.4.1). */
if( sig_alg == MBEDTLS_PK_NONE ||
- ( md_alg = mbedtls_ssl_sig_hash_set_find( &ssl->handshake->hash_algs,
- sig_alg ) ) == MBEDTLS_MD_NONE )
+ ( md_alg = mbedtls_ssl_sig_hash_set_find( ssl, sig_alg ) ) == MBEDTLS_MD_NONE )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
/* (... because we choose a cipher suite