Remember suitable hash function for any signature algorithm.

This commit changes `ssl_parse_signature_algorithms_ext` to remember
one suitable ( := supported by client and by our config ) hash
algorithm per signature algorithm.

It also modifies the ciphersuite checking function
`ssl_ciphersuite_match` to refuse a suite if there
is no suitable hash algorithm.

Finally, it adds the corresponding entry to the ChangeLog.
This commit is contained in:
Hanno Becker 2017-04-28 17:15:26 +01:00
parent 1aa267cbc3
commit 7e5437a972
7 changed files with 307 additions and 33 deletions

View file

@ -157,6 +157,24 @@
extern "C" {
#endif
#if defined(MBEDTLS_SSL_PROTO_TLS1_2) && \
defined(MBEDTLS_KEY_EXCHANGE__WITH_CERT__ENABLED)
/*
* Abstraction for a grid of allowed signature-hash-algorithm pairs.
*/
struct mbedtls_ssl_sig_hash_set_t
{
/* At the moment, we only need to remember a single suitable
* hash algorithm per signature algorithm. As long as that's
* the case - and we don't need a general lookup function -
* we can implement the sig-hash-set as a map from signatures
* to hash algorithms. */
mbedtls_md_type_t rsa;
mbedtls_md_type_t ecdsa;
};
#endif /* MBEDTLS_SSL_PROTO_TLS1_2 &&
MBEDTLS_KEY_EXCHANGE__WITH_CERT__ENABLED */
/*
* This structure contains the parameters only needed during handshake.
*/
@ -165,8 +183,11 @@ struct mbedtls_ssl_handshake_params
/*
* Handshake specific crypto variables
*/
int sig_alg; /*!< Hash algorithm for signature */
int verify_sig_alg; /*!< Signature algorithm for verify */
#if defined(MBEDTLS_SSL_PROTO_TLS1_2) && \
defined(MBEDTLS_KEY_EXCHANGE__WITH_CERT__ENABLED)
mbedtls_ssl_sig_hash_set_t hash_algs; /*!< Set of suitable sig-hash pairs */
#endif
#if defined(MBEDTLS_DHM_C)
mbedtls_dhm_context dhm_ctx; /*!< DHM key exchange */
#endif
@ -329,6 +350,28 @@ struct mbedtls_ssl_flight_item
};
#endif /* MBEDTLS_SSL_PROTO_DTLS */
#if defined(MBEDTLS_SSL_PROTO_TLS1_2) && \
defined(MBEDTLS_KEY_EXCHANGE__WITH_CERT__ENABLED)
/* Find an entry in a signature-hash set matching a given hash algorithm. */
mbedtls_md_type_t mbedtls_ssl_sig_hash_set_find( mbedtls_ssl_sig_hash_set_t *set,
mbedtls_pk_type_t sig_alg );
/* Add a signature-hash-pair to a signature-hash set */
void mbedtls_ssl_sig_hash_set_add( mbedtls_ssl_sig_hash_set_t *set,
mbedtls_pk_type_t sig_alg,
mbedtls_md_type_t md_alg );
/* Allow exactly one hash algorithm for each signature. */
void mbedtls_ssl_sig_hash_set_const_hash( mbedtls_ssl_sig_hash_set_t *set,
mbedtls_md_type_t md_alg );
/* Setup an empty signature-hash set */
static inline void mbedtls_ssl_sig_hash_set_init( mbedtls_ssl_sig_hash_set_t *set )
{
mbedtls_ssl_sig_hash_set_const_hash( set, MBEDTLS_MD_NONE );
}
#endif /* MBEDTLS_SSL_PROTO_TLS1_2) &&
MBEDTLS_KEY_EXCHANGE__WITH_CERT__ENABLED */
/**
* \brief Free referenced items in an SSL transform context and clear
@ -384,6 +427,7 @@ int mbedtls_ssl_psk_derive_premaster( mbedtls_ssl_context *ssl, mbedtls_key_exch
#if defined(MBEDTLS_PK_C)
unsigned char mbedtls_ssl_sig_from_pk( mbedtls_pk_context *pk );
unsigned char mbedtls_ssl_sig_from_pk_alg( mbedtls_pk_type_t type );
mbedtls_pk_type_t mbedtls_ssl_pk_alg_from_sig( unsigned char sig );
#endif