Add forbidden extensions check for ClientHello
Signed-off-by: Jerry Yu <jerry.h.yu@arm.com>
diff --git a/library/ssl_misc.h b/library/ssl_misc.h
index 41bb9c5..cf3010a 100644
--- a/library/ssl_misc.h
+++ b/library/ssl_misc.h
@@ -103,6 +103,93 @@
#define MBEDTLS_SSL_EXT_SIG_ALG_CERT ( 1 << 20 )
#define MBEDTLS_SSL_EXT_KEY_SHARE ( 1 << 21 )
+/* Except ServerHello, other message should ignore unrecognized extension.
+ *
+ * RFC 8446 page 31
+ *
+ * The ServerHello MUST only include extensions which are required to establish
+ * the cryptographic context and negotiate the protocol version.
+ *
+ * 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.
+ */
+#define MBEDTLS_SSL_EXT_UNRECOGNIZED ( 1U << 31 )
+
+/* RFC 8446 page 36. Allowed extensions for ClienHello */
+#define MBEDTLS_SSL_TLS1_3_ALLOWED_EXTS_OF_CH \
+ ( MBEDTLS_SSL_EXT_SERVERNAME | \
+ MBEDTLS_SSL_EXT_MAX_FRAGMENT_LENGTH | \
+ MBEDTLS_SSL_EXT_STATUS_REQUEST | \
+ MBEDTLS_SSL_EXT_SUPPORTED_GROUPS | \
+ MBEDTLS_SSL_EXT_SIG_ALG | \
+ MBEDTLS_SSL_EXT_USE_SRTP | \
+ MBEDTLS_SSL_EXT_HEARTBEAT | \
+ MBEDTLS_SSL_EXT_ALPN | \
+ MBEDTLS_SSL_EXT_SCT | \
+ MBEDTLS_SSL_EXT_CLI_CERT_TYPE | \
+ MBEDTLS_SSL_EXT_SERV_CERT_TYPE | \
+ MBEDTLS_SSL_EXT_PADDING | \
+ MBEDTLS_SSL_EXT_KEY_SHARE | \
+ MBEDTLS_SSL_EXT_PRE_SHARED_KEY | \
+ MBEDTLS_SSL_EXT_PSK_KEY_EXCHANGE_MODES | \
+ MBEDTLS_SSL_EXT_EARLY_DATA | \
+ MBEDTLS_SSL_EXT_COOKIE | \
+ MBEDTLS_SSL_EXT_SUPPORTED_VERSIONS | \
+ MBEDTLS_SSL_EXT_CERT_AUTH | \
+ MBEDTLS_SSL_EXT_POST_HANDSHAKE_AUTH | \
+ MBEDTLS_SSL_EXT_SIG_ALG_CERT | \
+ MBEDTLS_SSL_EXT_UNRECOGNIZED )
+
+/* RFC 8446 page 36. Allowed extensions for EncryptedExtensions */
+#define MBEDTLS_SSL_TLS1_3_ALLOWED_EXTS_OF_EE \
+ ( MBEDTLS_SSL_EXT_SERVERNAME | \
+ MBEDTLS_SSL_EXT_MAX_FRAGMENT_LENGTH | \
+ MBEDTLS_SSL_EXT_SUPPORTED_GROUPS | \
+ MBEDTLS_SSL_EXT_USE_SRTP | \
+ MBEDTLS_SSL_EXT_HEARTBEAT | \
+ MBEDTLS_SSL_EXT_ALPN | \
+ MBEDTLS_SSL_EXT_CLI_CERT_TYPE | \
+ MBEDTLS_SSL_EXT_SERV_CERT_TYPE | \
+ MBEDTLS_SSL_EXT_EARLY_DATA | \
+ MBEDTLS_SSL_EXT_UNRECOGNIZED )
+
+/* RFC 8446 page 36. Allowed extensions for CertificateRequest */
+#define MBEDTLS_SSL_TLS1_3_ALLOWED_EXTS_OF_CR \
+ ( MBEDTLS_SSL_EXT_STATUS_REQUEST | \
+ MBEDTLS_SSL_EXT_SIG_ALG | \
+ MBEDTLS_SSL_EXT_SCT | \
+ MBEDTLS_SSL_EXT_CERT_AUTH | \
+ MBEDTLS_SSL_EXT_OID_FILTERS | \
+ MBEDTLS_SSL_EXT_SIG_ALG_CERT | \
+ MBEDTLS_SSL_EXT_UNRECOGNIZED )
+
+/* RFC 8446 page 36. Allowed extensions for Certificate */
+#define MBEDTLS_SSL_TLS1_3_ALLOWED_EXTS_OF_CT \
+ ( MBEDTLS_SSL_EXT_STATUS_REQUEST | \
+ MBEDTLS_SSL_EXT_SCT | \
+ MBEDTLS_SSL_EXT_UNRECOGNIZED )
+
+/* RFC 8446 page 36. Allowed extensions for ServerHello */
+#define MBEDTLS_SSL_TLS1_3_ALLOWED_EXTS_OF_SH \
+ ( MBEDTLS_SSL_EXT_KEY_SHARE | \
+ MBEDTLS_SSL_EXT_PRE_SHARED_KEY | \
+ MBEDTLS_SSL_EXT_SUPPORTED_VERSIONS )
+
+/* RFC 8446 page 36. Allowed extensions for HelloRetryRequest */
+#define MBEDTLS_SSL_TLS1_3_ALLOWED_EXTS_OF_HRR \
+ ( MBEDTLS_SSL_EXT_KEY_SHARE | \
+ MBEDTLS_SSL_EXT_COOKIE | \
+ MBEDTLS_SSL_EXT_SUPPORTED_VERSIONS | \
+ MBEDTLS_SSL_EXT_UNRECOGNIZED )
+
+/* RFC 8446 page 36. Allowed extensions for NewSessionTicket */
+#define MBEDTLS_SSL_TLS1_3_ALLOWED_EXTS_OF_NST \
+ ( MBEDTLS_SSL_EXT_EARLY_DATA | \
+ MBEDTLS_SSL_EXT_UNRECOGNIZED )
+
/*
* Helper macros for function call with return check.
*/
@@ -858,7 +945,7 @@
#endif
#if defined(MBEDTLS_SSL_PROTO_TLS1_3)
- int extensions_present; /*!< extension presence; Each bitfield
+ uint32_t extensions_present; /*!< extension presence; Each bitfield
represents an extension and defined
as \c MBEDTLS_SSL_EXT_XXX */
@@ -1839,6 +1926,90 @@
MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_PSK_ENABLED */
/*
+ * Helper functions to check if the extension is allowed or forbiden
+ */
+static inline int mbedtls_ssl_tls13_has_extensions( mbedtls_ssl_context *ssl,
+ int extensions_mask )
+{
+ int masked = ssl->handshake->extensions_present & extensions_mask;
+ return( masked != 0 );
+}
+
+static inline int mbedtls_tls13_get_extension_mask( uint16_t extension_type )
+{
+ switch( extension_type )
+ {
+ case MBEDTLS_TLS_EXT_SERVERNAME:
+ return( MBEDTLS_SSL_EXT_SERVERNAME );
+
+ case MBEDTLS_TLS_EXT_MAX_FRAGMENT_LENGTH:
+ return( MBEDTLS_SSL_EXT_MAX_FRAGMENT_LENGTH );
+
+ case MBEDTLS_TLS_EXT_STATUS_REQUEST:
+ return( MBEDTLS_SSL_EXT_STATUS_REQUEST );
+
+ case MBEDTLS_TLS_EXT_SUPPORTED_GROUPS:
+ return( MBEDTLS_SSL_EXT_SUPPORTED_GROUPS );
+
+ case MBEDTLS_TLS_EXT_SIG_ALG:
+ return( MBEDTLS_SSL_EXT_SIG_ALG );
+
+ case MBEDTLS_TLS_EXT_USE_SRTP:
+ return( MBEDTLS_SSL_EXT_USE_SRTP );
+
+ case MBEDTLS_TLS_EXT_HEARTBEAT:
+ return( MBEDTLS_SSL_EXT_HEARTBEAT );
+
+ case MBEDTLS_TLS_EXT_ALPN:
+ return( MBEDTLS_SSL_EXT_ALPN );
+
+ case MBEDTLS_TLS_EXT_SCT:
+ return( MBEDTLS_SSL_EXT_SCT );
+
+ case MBEDTLS_TLS_EXT_CLI_CERT_TYPE:
+ return( MBEDTLS_SSL_EXT_CLI_CERT_TYPE );
+
+ case MBEDTLS_TLS_EXT_SERV_CERT_TYPE:
+ return( MBEDTLS_SSL_EXT_SERV_CERT_TYPE );
+
+ case MBEDTLS_TLS_EXT_PADDING:
+ return( MBEDTLS_SSL_EXT_PADDING );
+
+ case MBEDTLS_TLS_EXT_PRE_SHARED_KEY:
+ return( MBEDTLS_SSL_EXT_PRE_SHARED_KEY );
+
+ case MBEDTLS_TLS_EXT_EARLY_DATA:
+ return( MBEDTLS_SSL_EXT_EARLY_DATA );
+
+ case MBEDTLS_TLS_EXT_SUPPORTED_VERSIONS:
+ return( MBEDTLS_SSL_EXT_SUPPORTED_VERSIONS );
+
+ case MBEDTLS_TLS_EXT_COOKIE:
+ return( MBEDTLS_SSL_EXT_COOKIE );
+
+ case MBEDTLS_TLS_EXT_PSK_KEY_EXCHANGE_MODES:
+ return( MBEDTLS_SSL_EXT_PSK_KEY_EXCHANGE_MODES );
+
+ case MBEDTLS_TLS_EXT_CERT_AUTH:
+ return( MBEDTLS_SSL_EXT_CERT_AUTH );
+
+ case MBEDTLS_TLS_EXT_OID_FILTERS:
+ return( MBEDTLS_SSL_EXT_OID_FILTERS );
+
+ case MBEDTLS_TLS_EXT_POST_HANDSHAKE_AUTH:
+ return( MBEDTLS_SSL_EXT_POST_HANDSHAKE_AUTH );
+
+ case MBEDTLS_TLS_EXT_SIG_ALG_CERT:
+ return( MBEDTLS_SSL_EXT_SIG_ALG_CERT );
+
+ case MBEDTLS_TLS_EXT_KEY_SHARE:
+ return( MBEDTLS_SSL_EXT_KEY_SHARE );
+ };
+
+ return( MBEDTLS_SSL_EXT_UNRECOGNIZED );
+}
+
+/*
* Helper functions to check the selected key exchange mode.
*/
static inline int mbedtls_ssl_tls13_key_exchange_mode_check(
diff --git a/library/ssl_tls13_server.c b/library/ssl_tls13_server.c
index b24aa4a..32f64d7 100644
--- a/library/ssl_tls13_server.c
+++ b/library/ssl_tls13_server.c
@@ -1239,6 +1239,7 @@
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 @@
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 @@
* 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 @@
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 @@
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 @@
return( ret );
}
- ssl->handshake->extensions_present |= MBEDTLS_SSL_EXT_SUPPORTED_GROUPS;
break;
#endif /* MBEDTLS_ECDH_C */
@@ -1515,7 +1535,6 @@
return( ret );
}
- ssl->handshake->extensions_present |= MBEDTLS_SSL_EXT_KEY_SHARE;
break;
#endif /* MBEDTLS_ECDH_C */
@@ -1530,7 +1549,6 @@
( "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 @@
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 @@
*/
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 @@
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 @@
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 @@
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 @@
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 @@
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 );