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Add extension check for ServerHello and HRR

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Signed-off-by: Jerry Yu <jerry.h.yu@arm.com>
This commit is contained in:
Jerry Yu 2022-08-04 17:42:49 +08:00
parent 2eaa76044b
commit 2c5363e58b
1 changed files with 44 additions and 6 deletions
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50
library/ssl_tls13_client.c
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@ -1496,6 +1496,7 @@ static int ssl_tls13_parse_server_hello( mbedtls_ssl_context *ssl,
mbedtls_ssl_handshake_params *handshake = ssl->handshake;
size_t extensions_len;
const unsigned char *extensions_end;
uint32_t extensions_present, allowed_extension_mask;
uint16_t cipher_suite;
const mbedtls_ssl_ciphersuite_t *ciphersuite_info;
int fatal_alert = 0;
@ -1641,6 +1642,11 @@ static int ssl_tls13_parse_server_hello( mbedtls_ssl_context *ssl,
MBEDTLS_SSL_DEBUG_BUF( 3, "server hello extensions", p, extensions_len );
extensions_present = MBEDTLS_SSL_EXT_NONE;
allowed_extension_mask = is_hrr ?
MBEDTLS_SSL_TLS1_3_ALLOWED_EXTS_OF_HRR :
MBEDTLS_SSL_TLS1_3_ALLOWED_EXTS_OF_SH;
while( p < extensions_end )
{
unsigned int extension_type;
@ -1655,6 +1661,24 @@ static int ssl_tls13_parse_server_hello( mbedtls_ssl_context *ssl,
MBEDTLS_SSL_CHK_BUF_READ_PTR( p, extensions_end, extension_data_len );
extension_data_end = p + extension_data_len;
/* RFC 8446 page 35
*
* If an implementation receives an extension which it recognizes and which
* is not specified for the message in which it appears, it MUST abort the
* handshake with an "illegal_parameter" alert.
*/
extensions_present |= mbedtls_tls13_get_extension_mask( extension_type );
MBEDTLS_SSL_DEBUG_MSG( 3,
( "%s: received %s(%u) extension",
is_hrr ? "hello retry request" : "server hello",
mbedtls_tls13_get_extension_name( extension_type ),
extension_type ) );
if( ( extensions_present & allowed_extension_mask ) == 0 )
{
fatal_alert = MBEDTLS_SSL_ALERT_MSG_ILLEGAL_PARAMETER;
goto cleanup;
}
switch( extension_type )
{
case MBEDTLS_TLS_EXT_COOKIE:
@ -1727,18 +1751,32 @@ static int ssl_tls13_parse_server_hello( mbedtls_ssl_context *ssl,
break;
default:
MBEDTLS_SSL_DEBUG_MSG(
3,
( "unknown extension found: %u ( ignoring )",
MBEDTLS_SSL_DEBUG_MSG( 3,
( "%s: ignore %s(%u) extension",
is_hrr ? "hello retry request" : "server hello",
mbedtls_tls13_get_extension_name( extension_type ),
extension_type ) );
fatal_alert = MBEDTLS_SSL_ALERT_MSG_UNSUPPORTED_EXT;
goto cleanup;
break;
}
p += extension_data_len;
}
MBEDTLS_SSL_TLS1_3_PRINT_EXTS(
3, is_hrr ? "HelloRetryRequest" : "ServerHello", extensions_present );
/* RFC 8446 page 102
* - "supported_versions" is REQUIRED for all ClientHello, ServerHello, and
* HelloRetryRequest messages.
*/
if( ( extensions_present & MBEDTLS_SSL_EXT_SUPPORTED_VERSIONS ) == 0 )
{
MBEDTLS_SSL_DEBUG_MSG( 1,
( "%s: supported_versions not found",
is_hrr ? "hello retry request" : "server hello" ) );
fatal_alert = MBEDTLS_SSL_ALERT_MSG_ILLEGAL_PARAMETER;
}
cleanup:
if( fatal_alert == MBEDTLS_SSL_ALERT_MSG_UNSUPPORTED_EXT )