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Same ciphersuite validation in server and client hello

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This commit is contained in:
Mohammad Azim Khan 2018-04-18 19:35:00 +01:00
parent f2b76cd45c
commit 1d3b508b82
2 changed files with 55 additions and 39 deletions
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2
ChangeLog
View file

@ -64,6 +64,8 @@ Bugfix
* Fix buffer length assertions in the ssl_parse_certificate_request()
function which leads to a potential one byte overread of the message
buffer.
* Fix cipher suite validation in ssl_parse_server_hello() by performing same
checks as performed in ssl_write_client_hello().
Changes
* Remove some redundant code in bignum.c. Contributed by Alexey Skalozub.

92
library/ssl_cli.c
View file

@ -717,6 +717,45 @@ static int ssl_generate_random( mbedtls_ssl_context *ssl )
return( 0 );
}
/**
* \brief Validate cipher suite against config in SSL context.
*
* \param suite_info cipher suite to validate
* \param ssl SSL context
*
* \return 0 if valid, else 1
*/
static int ssl_validate_ciphersuite( const mbedtls_ssl_ciphersuite_t * suite_info,
const mbedtls_ssl_context * ssl )
{
if( suite_info == NULL )
return( 1 );
if( suite_info->min_minor_ver > ssl->conf->max_minor_ver ||
suite_info->max_minor_ver < ssl->conf->min_minor_ver )
return( 1 );
#if defined(MBEDTLS_SSL_PROTO_DTLS)
if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM &&
( suite_info->flags & MBEDTLS_CIPHERSUITE_NODTLS ) )
return( 1 );
#endif
#if defined(MBEDTLS_ARC4_C)
if( ssl->conf->arc4_disabled == MBEDTLS_SSL_ARC4_DISABLED &&
suite_info->cipher == MBEDTLS_CIPHER_ARC4_128 )
return( 1 );
#endif
#if defined(MBEDTLS_KEY_EXCHANGE_ECJPAKE_ENABLED)
if( suite_info->key_exchange == MBEDTLS_KEY_EXCHANGE_ECJPAKE &&
mbedtls_ecjpake_check( &ssl->handshake->ecjpake_ctx ) != 0 )
return( 1 );
#endif
return( 0 );
}
static int ssl_write_client_hello( mbedtls_ssl_context *ssl )
{
int ret;
@ -869,31 +908,9 @@ static int ssl_write_client_hello( mbedtls_ssl_context *ssl )
{
ciphersuite_info = mbedtls_ssl_ciphersuite_from_id( ciphersuites[i] );
if( ciphersuite_info == NULL )
if( ssl_validate_ciphersuite( ciphersuite_info, ssl ) != 0 )
continue;
if( ciphersuite_info->min_minor_ver > ssl->conf->max_minor_ver ||
ciphersuite_info->max_minor_ver < ssl->conf->min_minor_ver )
continue;
#if defined(MBEDTLS_SSL_PROTO_DTLS)
if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM &&
( ciphersuite_info->flags & MBEDTLS_CIPHERSUITE_NODTLS ) )
continue;
#endif
#if defined(MBEDTLS_ARC4_C)
if( ssl->conf->arc4_disabled == MBEDTLS_SSL_ARC4_DISABLED &&
ciphersuite_info->cipher == MBEDTLS_CIPHER_ARC4_128 )
continue;
#endif
#if defined(MBEDTLS_KEY_EXCHANGE_ECJPAKE_ENABLED)
if( ciphersuite_info->key_exchange == MBEDTLS_KEY_EXCHANGE_ECJPAKE &&
mbedtls_ecjpake_check( &ssl->handshake->ecjpake_ctx ) != 0 )
continue;
#endif
MBEDTLS_SSL_DEBUG_MSG( 3, ( "client hello, add ciphersuite: %04x",
ciphersuites[i] ) );
@ -1690,22 +1707,8 @@ static int ssl_parse_server_hello( mbedtls_ssl_context *ssl )
MBEDTLS_SSL_DEBUG_MSG( 3, ( "server hello, chosen ciphersuite: %04x", i ) );
MBEDTLS_SSL_DEBUG_MSG( 3, ( "server hello, compress alg.: %d", buf[37 + n] ) );
suite_info = mbedtls_ssl_ciphersuite_from_id( ssl->session_negotiate->ciphersuite );
if( suite_info == NULL
#if defined(MBEDTLS_ARC4_C)
|| ( ssl->conf->arc4_disabled &&
suite_info->cipher == MBEDTLS_CIPHER_ARC4_128 )
#endif
)
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad server hello message" ) );
mbedtls_ssl_send_alert_message( ssl, MBEDTLS_SSL_ALERT_LEVEL_FATAL,
MBEDTLS_SSL_ALERT_MSG_ILLEGAL_PARAMETER );
return( MBEDTLS_ERR_SSL_BAD_HS_SERVER_HELLO );
}
MBEDTLS_SSL_DEBUG_MSG( 3, ( "server hello, chosen ciphersuite: %s", suite_info->name ) );
/* Perform cipher suite validation in same way as in ssl_write_client_hello.
*/
i = 0;
while( 1 )
{
@ -1724,6 +1727,17 @@ static int ssl_parse_server_hello( mbedtls_ssl_context *ssl )
}
}
suite_info = mbedtls_ssl_ciphersuite_from_id( ssl->session_negotiate->ciphersuite );
if( ssl_validate_ciphersuite( suite_info, ssl ) != 0 )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad server hello message" ) );
mbedtls_ssl_send_alert_message( ssl, MBEDTLS_SSL_ALERT_LEVEL_FATAL,
MBEDTLS_SSL_ALERT_MSG_ILLEGAL_PARAMETER );
return( MBEDTLS_ERR_SSL_BAD_HS_SERVER_HELLO );
}
MBEDTLS_SSL_DEBUG_MSG( 3, ( "server hello, chosen ciphersuite: %s", suite_info->name ) );
if( comp != MBEDTLS_SSL_COMPRESS_NULL
#if defined(MBEDTLS_ZLIB_SUPPORT)
&& comp != MBEDTLS_SSL_COMPRESS_DEFLATE