Merged client ciphersuite order preference option
diff --git a/ChangeLog b/ChangeLog
index b1cbb00..77d921c 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -3,6 +3,8 @@
= PolarSSL 1.3 branch
Features
* EC key generation support in gen_key app
+ * Support for adhering to client ciphersuite order preference
+ (POLARSSL_SSL_SRV_RESPECT_CLIENT_PREFERENCE)
Changes
* gen_prime() speedup
diff --git a/include/polarssl/config.h b/include/polarssl/config.h
index 8390511..bdd40af 100644
--- a/include/polarssl/config.h
+++ b/include/polarssl/config.h
@@ -632,6 +632,16 @@
#define POLARSSL_SSL_SRV_SUPPORT_SSLV2_CLIENT_HELLO
/**
+ * \def POLARSSL_SSL_SRV_RESPECT_CLIENT_PREFERENCE
+ *
+ * Pick the ciphersuite according to the client's preferences rather than ours
+ * in the SSL Server module (POLARSSL_SSL_SRV_C).
+ *
+ * Uncomment this macro to respect client's ciphersuite order
+ */
+//#define POLARSSL_SSL_SRV_RESPECT_CLIENT_PREFERENCE
+
+/**
* \def POLARSSL_SSL_MAX_FRAGMENT_LENGTH
*
* Enable support for RFC 6066 max_fragment_length extension in SSL.
diff --git a/library/ssl_srv.c b/library/ssl_srv.c
index 530c866..0c6c0d7 100644
--- a/library/ssl_srv.c
+++ b/library/ssl_srv.c
@@ -680,6 +680,129 @@
}
#endif /* POLARSSL_SSL_SESSION_TICKETS */
+/*
+ * Auxiliary functions for ServerHello parsing and related actions
+ */
+
+#if defined(POLARSSL_X509_CRT_PARSE_C)
+/*
+ * Return 1 if the given EC key uses the given curve, 0 otherwise
+ */
+#if defined(POLARSSL_ECDSA_C)
+static int ssl_key_matches_curves( pk_context *pk,
+ const ecp_curve_info **curves )
+{
+ const ecp_curve_info **crv = curves;
+ ecp_group_id grp_id = pk_ec( *pk )->grp.id;
+
+ while( *crv != NULL )
+ {
+ if( (*crv)->grp_id == grp_id )
+ return( 1 );
+ crv++;
+ }
+
+ return( 0 );
+}
+#endif /* POLARSSL_ECDSA_C */
+
+/*
+ * Try picking a certificate for this ciphersuite,
+ * return 0 on success and -1 on failure.
+ */
+static int ssl_pick_cert( ssl_context *ssl,
+ const ssl_ciphersuite_t * ciphersuite_info )
+{
+ ssl_key_cert *cur, *list;
+ pk_type_t pk_alg = ssl_get_ciphersuite_sig_pk_alg( ciphersuite_info );
+
+#if defined(POLARSSL_SSL_SERVER_NAME_INDICATION)
+ if( ssl->handshake->sni_key_cert != NULL )
+ list = ssl->handshake->sni_key_cert;
+ else
+#endif
+ list = ssl->handshake->key_cert;
+
+ if( pk_alg == POLARSSL_PK_NONE )
+ return( 0 );
+
+ for( cur = list; cur != NULL; cur = cur->next )
+ {
+ if( ! pk_can_do( cur->key, pk_alg ) )
+ continue;
+
+#if defined(POLARSSL_ECDSA_C)
+ if( pk_alg == POLARSSL_PK_ECDSA )
+ {
+ if( ssl_key_matches_curves( cur->key, ssl->handshake->curves ) )
+ break;
+ }
+ else
+#endif
+ break;
+ }
+
+ if( cur == NULL )
+ return( -1 );
+
+ ssl->handshake->key_cert = cur;
+ return( 0 );
+}
+#endif /* POLARSSL_X509_CRT_PARSE_C */
+
+/*
+ * Check if a given ciphersuite is suitable for use with our config/keys/etc
+ * Sets ciphersuite_info only if the suite matches.
+ */
+static int ssl_ciphersuite_match( ssl_context *ssl, int suite_id,
+ const ssl_ciphersuite_t **ciphersuite_info )
+{
+ const ssl_ciphersuite_t *suite_info;
+
+ suite_info = ssl_ciphersuite_from_id( suite_id );
+ if( suite_info == NULL )
+ {
+ SSL_DEBUG_MSG( 1, ( "ciphersuite info for %04x not found", suite_id ) );
+ return( POLARSSL_ERR_SSL_BAD_INPUT_DATA );
+ }
+
+ if( suite_info->min_minor_ver > ssl->minor_ver ||
+ suite_info->max_minor_ver < ssl->minor_ver )
+ return( 0 );
+
+#if defined(POLARSSL_ECDH_C) || defined(POLARSSL_ECDSA_C)
+ if( ssl_ciphersuite_uses_ec( suite_info ) &&
+ ( ssl->handshake->curves == NULL ||
+ ssl->handshake->curves[0] == NULL ) )
+ return( 0 );
+#endif
+
+#if defined(POLARSSL_KEY_EXCHANGE__SOME__PSK_ENABLED)
+ /* If the ciphersuite requires a pre-shared key and we don't
+ * have one, skip it now rather than failing later */
+ if( ssl_ciphersuite_uses_psk( suite_info ) &&
+ ssl->f_psk == NULL &&
+ ( ssl->psk == NULL || ssl->psk_identity == NULL ||
+ ssl->psk_identity_len == 0 || ssl->psk_len == 0 ) )
+ return( 0 );
+#endif
+
+#if defined(POLARSSL_X509_CRT_PARSE_C)
+ /*
+ * Final check: if ciphersuite requires us to have a
+ * certificate/key of a particular type:
+ * - select the appropriate certificate if we have one, or
+ * - try the next ciphersuite if we don't
+ * This must be done last since we modify the key_cert list.
+ */
+ if( ssl_pick_cert( ssl, suite_info ) != 0 )
+ return( 0 );
+#endif
+
+ *ciphersuite_info = suite_info;
+ return( 0 );
+}
+
#if defined(POLARSSL_SSL_SRV_SUPPORT_SSLV2_CLIENT_HELLO)
static int ssl_parse_client_hello_v2( ssl_context *ssl )
{
@@ -851,31 +974,28 @@
}
ciphersuites = ssl->ciphersuite_list[ssl->minor_ver];
+ ciphersuite_info = NULL;
+#if defined(POLARSSL_SSL_SRV_RESPECT_CLIENT_PREFERENCE)
+ for( j = 0, p = buf + 6; j < ciph_len; j += 3, p += 3 )
+ {
+ for( i = 0; ciphersuites[i] != 0; i++ )
+#else
for( i = 0; ciphersuites[i] != 0; i++ )
{
for( j = 0, p = buf + 6; j < ciph_len; j += 3, p += 3 )
+#endif
{
- // Only allow non-ECC ciphersuites as we do not have extensions
- //
- if( p[0] == 0 && p[1] == 0 &&
- ( ( ciphersuites[i] >> 8 ) & 0xFF ) == 0 &&
- p[2] == ( ciphersuites[i] & 0xFF ) )
- {
- ciphersuite_info = ssl_ciphersuite_from_id( ciphersuites[i] );
+ if( p[0] != 0 ||
+ p[1] != ( ( ciphersuites[i] >> 8 ) & 0xFF ) ||
+ p[2] != ( ( ciphersuites[i] ) & 0xFF ) )
+ continue;
- if( ciphersuite_info == NULL )
- {
- SSL_DEBUG_MSG( 1, ( "ciphersuite info for %02x not found",
- ciphersuites[i] ) );
- return( POLARSSL_ERR_SSL_BAD_INPUT_DATA );
- }
+ if( ( ret = ssl_ciphersuite_match( ssl, ciphersuites[i],
+ &ciphersuite_info ) ) != 0 )
+ return( ret );
- if( ciphersuite_info->min_minor_ver > ssl->minor_ver ||
- ciphersuite_info->max_minor_ver < ssl->minor_ver )
- continue;
-
+ if( ciphersuite_info != NULL )
goto have_ciphersuite_v2;
- }
}
}
@@ -911,69 +1031,6 @@
}
#endif /* POLARSSL_SSL_SRV_SUPPORT_SSLV2_CLIENT_HELLO */
-#if defined(POLARSSL_X509_CRT_PARSE_C)
-#if defined(POLARSSL_ECDSA_C)
-static int ssl_key_matches_curves( pk_context *pk,
- const ecp_curve_info **curves )
-{
- const ecp_curve_info **crv = curves;
- ecp_group_id grp_id = pk_ec( *pk )->grp.id;
-
- while( *crv != NULL )
- {
- if( (*crv)->grp_id == grp_id )
- return( 1 );
- crv++;
- }
-
- return( 0 );
-}
-#endif /* POLARSSL_ECDSA_C */
-
-/*
- * Try picking a certificate for this ciphersuite,
- * return 0 on success and -1 on failure.
- */
-static int ssl_pick_cert( ssl_context *ssl,
- const ssl_ciphersuite_t * ciphersuite_info )
-{
- ssl_key_cert *cur, *list;
- pk_type_t pk_alg = ssl_get_ciphersuite_sig_pk_alg( ciphersuite_info );
-
-#if defined(POLARSSL_SSL_SERVER_NAME_INDICATION)
- if( ssl->handshake->sni_key_cert != NULL )
- list = ssl->handshake->sni_key_cert;
- else
-#endif
- list = ssl->handshake->key_cert;
-
- if( pk_alg == POLARSSL_PK_NONE )
- return( 0 );
-
- for( cur = list; cur != NULL; cur = cur->next )
- {
- if( ! pk_can_do( cur->key, pk_alg ) )
- continue;
-
-#if defined(POLARSSL_ECDSA_C)
- if( pk_alg == POLARSSL_PK_ECDSA )
- {
- if( ssl_key_matches_curves( cur->key, ssl->handshake->curves ) )
- break;
- }
- else
-#endif
- break;
- }
-
- if( cur == NULL )
- return( -1 );
-
- ssl->handshake->key_cert = cur;
- return( 0 );
-}
-#endif /* POLARSSL_X509_CRT_PARSE_C */
-
static int ssl_parse_client_hello( ssl_context *ssl )
{
int ret;
@@ -1372,58 +1429,27 @@
* and certificate from the SNI callback triggered by the SNI extension.)
*/
ciphersuites = ssl->ciphersuite_list[ssl->minor_ver];
+ ciphersuite_info = NULL;
+#if defined(POLARSSL_SSL_SRV_RESPECT_CLIENT_PREFERENCE)
+ for( j = 0, p = buf + 41 + sess_len; j < ciph_len; j += 2, p += 2 )
+ {
+ for( i = 0; ciphersuites[i] != 0; i++ )
+#else
for( i = 0; ciphersuites[i] != 0; i++ )
{
- for( j = 0, p = buf + 41 + sess_len; j < ciph_len;
- j += 2, p += 2 )
+ for( j = 0, p = buf + 41 + sess_len; j < ciph_len; j += 2, p += 2 )
+#endif
{
- if( p[0] == ( ( ciphersuites[i] >> 8 ) & 0xFF ) &&
- p[1] == ( ( ciphersuites[i] ) & 0xFF ) )
- {
- ciphersuite_info = ssl_ciphersuite_from_id( ciphersuites[i] );
+ if( p[0] != ( ( ciphersuites[i] >> 8 ) & 0xFF ) ||
+ p[1] != ( ( ciphersuites[i] ) & 0xFF ) )
+ continue;
- if( ciphersuite_info == NULL )
- {
- SSL_DEBUG_MSG( 1, ( "ciphersuite info for %04x not found",
- ciphersuites[i] ) );
- return( POLARSSL_ERR_SSL_BAD_INPUT_DATA );
- }
+ if( ( ret = ssl_ciphersuite_match( ssl, ciphersuites[i],
+ &ciphersuite_info ) ) != 0 )
+ return( ret );
- if( ciphersuite_info->min_minor_ver > ssl->minor_ver ||
- ciphersuite_info->max_minor_ver < ssl->minor_ver )
- continue;
-
-#if defined(POLARSSL_ECDH_C) || defined(POLARSSL_ECDSA_C)
- if( ssl_ciphersuite_uses_ec( ciphersuite_info ) &&
- ( ssl->handshake->curves == NULL ||
- ssl->handshake->curves[0] == NULL ) )
- continue;
-#endif
-
-#if defined(POLARSSL_KEY_EXCHANGE__SOME__PSK_ENABLED)
- /* If the ciphersuite requires a pre-shared key and we don't
- * have one, skip it now rather than failing later */
- if( ssl_ciphersuite_uses_psk( ciphersuite_info ) &&
- ssl->f_psk == NULL &&
- ( ssl->psk == NULL || ssl->psk_identity == NULL ||
- ssl->psk_identity_len == 0 || ssl->psk_len == 0 ) )
- continue;
-#endif
-
-#if defined(POLARSSL_X509_CRT_PARSE_C)
- /*
- * Final check: if ciphersuite requires us to have a
- * certificate/key of a particular type:
- * - select the appropriate certificate if we have one, or
- * - try the next ciphersuite if we don't
- * This must be done last since we modify the key_cert list.
- */
- if( ssl_pick_cert( ssl, ciphersuite_info ) != 0 )
- continue;
-#endif
-
+ if( ciphersuite_info != NULL )
goto have_ciphersuite;
- }
}
}