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Add forbidden extensions check for ClientHello

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Signed-off-by: Jerry Yu <jerry.h.yu@arm.com>
This commit is contained in:
Jerry Yu
2022-08-04 16:29:22 +08:00
parent 471dee5a12
commit e18dc7eb9a
2 changed files with 216 additions and 14 deletions
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57
library/ssl_tls13_server.c
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@ -1239,6 +1239,7 @@ static int ssl_tls13_parse_client_hello( mbedtls_ssl_context *ssl,
const unsigned char *cipher_suites_end;
size_t extensions_len;
const unsigned char *extensions_end;
uint32_t extensions_present;
int hrr_required = 0;
#if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_PSK_ENABLED)
@ -1247,7 +1248,7 @@ static int ssl_tls13_parse_client_hello( mbedtls_ssl_context *ssl,
const unsigned char *pre_shared_key_ext_end = NULL;
#endif
ssl->handshake->extensions_present = MBEDTLS_SSL_EXT_NONE;
extensions_present = MBEDTLS_SSL_EXT_NONE;
/*
* ClientHello layout:
@ -1431,7 +1432,7 @@ static int ssl_tls13_parse_client_hello( mbedtls_ssl_context *ssl,
* Servers MUST check that it is the last extension and otherwise fail
* the handshake with an "illegal_parameter" alert.
*/
if( ssl->handshake->extensions_present & MBEDTLS_SSL_EXT_PRE_SHARED_KEY )
if( extensions_present & MBEDTLS_SSL_EXT_PRE_SHARED_KEY )
{
MBEDTLS_SSL_DEBUG_MSG(
3, ( "pre_shared_key is not last extension." ) );
@ -1449,6 +1450,27 @@ static int ssl_tls13_parse_client_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,
( "client hello : received %s(%u) extension",
mbedtls_tls13_get_extension_name( extension_type ),
extension_type ) );
if( ( extensions_present & MBEDTLS_SSL_TLS1_3_ALLOWED_EXTS_OF_CH ) == 0 )
{
MBEDTLS_SSL_DEBUG_MSG(
3, ( "forbidden extension received." ) );
MBEDTLS_SSL_PEND_FATAL_ALERT(
MBEDTLS_SSL_ALERT_MSG_ILLEGAL_PARAMETER,
MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE );
return( MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE );
}
switch( extension_type )
{
#if defined(MBEDTLS_SSL_SERVER_NAME_INDICATION)
@ -1462,7 +1484,6 @@ static int ssl_tls13_parse_client_hello( mbedtls_ssl_context *ssl,
1, "mbedtls_ssl_parse_servername_ext", ret );
return( ret );
}
ssl->handshake->extensions_present |= MBEDTLS_SSL_EXT_SERVERNAME;
break;
#endif /* MBEDTLS_SSL_SERVER_NAME_INDICATION */
@ -1485,7 +1506,6 @@ static int ssl_tls13_parse_client_hello( mbedtls_ssl_context *ssl,
return( ret );
}
ssl->handshake->extensions_present |= MBEDTLS_SSL_EXT_SUPPORTED_GROUPS;
break;
#endif /* MBEDTLS_ECDH_C */
@ -1515,7 +1535,6 @@ static int ssl_tls13_parse_client_hello( mbedtls_ssl_context *ssl,
return( ret );
}
ssl->handshake->extensions_present |= MBEDTLS_SSL_EXT_KEY_SHARE;
break;
#endif /* MBEDTLS_ECDH_C */
@ -1530,7 +1549,6 @@ static int ssl_tls13_parse_client_hello( mbedtls_ssl_context *ssl,
( "ssl_tls13_parse_supported_versions_ext" ), ret );
return( ret );
}
ssl->handshake->extensions_present |= MBEDTLS_SSL_EXT_SUPPORTED_VERSIONS;
break;
#if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_PSK_ENABLED)
@ -1546,13 +1564,12 @@ static int ssl_tls13_parse_client_hello( mbedtls_ssl_context *ssl,
return( ret );
}
ssl->handshake->extensions_present |= MBEDTLS_SSL_EXT_PSK_KEY_EXCHANGE_MODES;
break;
#endif
case MBEDTLS_TLS_EXT_PRE_SHARED_KEY:
MBEDTLS_SSL_DEBUG_MSG( 3, ( "found pre_shared_key extension" ) );
if( ( ssl->handshake->extensions_present &
if( ( extensions_present &
MBEDTLS_SSL_EXT_PSK_KEY_EXCHANGE_MODES ) == 0 )
{
MBEDTLS_SSL_PEND_FATAL_ALERT(
@ -1567,8 +1584,7 @@ static int ssl_tls13_parse_client_hello( mbedtls_ssl_context *ssl,
*/
pre_shared_key_ext = p;
pre_shared_key_ext_end = extension_data_end;
#endif
ssl->handshake->extensions_present |= MBEDTLS_SSL_EXT_PRE_SHARED_KEY;
#endif /* MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_PSK_ENABLED */
break;
#if defined(MBEDTLS_SSL_ALPN)
@ -1582,7 +1598,6 @@ static int ssl_tls13_parse_client_hello( mbedtls_ssl_context *ssl,
1, ( "mbedtls_ssl_parse_alpn_ext" ), ret );
return( ret );
}
ssl->handshake->extensions_present |= MBEDTLS_SSL_EXT_ALPN;
break;
#endif /* MBEDTLS_SSL_ALPN */
@ -1599,7 +1614,6 @@ static int ssl_tls13_parse_client_hello( mbedtls_ssl_context *ssl,
ret ) );
return( ret );
}
ssl->handshake->extensions_present |= MBEDTLS_SSL_EXT_SIG_ALG;
break;
#endif /* MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_EPHEMERAL_ENABLED */
@ -1613,6 +1627,22 @@ static int ssl_tls13_parse_client_hello( mbedtls_ssl_context *ssl,
p += extension_data_len;
}
MBEDTLS_SSL_TLS1_3_PRINT_EXTS( 3, "ClientHello", 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,
( "client hello: supported_versions not found" ) );
MBEDTLS_SSL_PEND_FATAL_ALERT(
MBEDTLS_SSL_ALERT_MSG_MISSING_EXTENSION,
MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE );
return( MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE );
}
mbedtls_ssl_add_hs_hdr_to_checksum( ssl,
MBEDTLS_SSL_HS_CLIENT_HELLO,
p - buf );
@ -1636,7 +1666,7 @@ static int ssl_tls13_parse_client_hello( mbedtls_ssl_context *ssl,
cipher_suites_end );
if( ret == MBEDTLS_ERR_SSL_UNKNOWN_IDENTITY )
{
ssl->handshake->extensions_present &= ~MBEDTLS_SSL_EXT_PRE_SHARED_KEY;
extensions_present &= ~MBEDTLS_SSL_EXT_PRE_SHARED_KEY;
}
else if( ret != 0 )
{
@ -1651,6 +1681,7 @@ static int ssl_tls13_parse_client_hello( mbedtls_ssl_context *ssl,
ssl->handshake->update_checksum( ssl, buf, p - buf );
}
ssl->handshake->extensions_present = extensions_present;
ret = ssl_tls13_determine_key_exchange_mode( ssl );
if( ret < 0 )
return( ret );