| /* |
| * TLS 1.3 server-side functions |
| * |
| * Copyright The Mbed TLS Contributors |
| * SPDX-License-Identifier: Apache-2.0 |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); you may |
| * not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT |
| * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| #include "common.h" |
| |
| #if defined(MBEDTLS_SSL_SRV_C) && defined(MBEDTLS_SSL_PROTO_TLS1_3) |
| |
| #include "mbedtls/debug.h" |
| |
| #include "ssl_misc.h" |
| #include "ssl_tls13_keys.h" |
| #include "ssl_debug_helpers.h" |
| #include <string.h> |
| #if defined(MBEDTLS_ECP_C) |
| #include "mbedtls/ecp.h" |
| #endif /* MBEDTLS_ECP_C */ |
| |
| #if defined(MBEDTLS_PLATFORM_C) |
| #include "mbedtls/platform.h" |
| #else |
| #include <stdlib.h> |
| #define mbedtls_calloc calloc |
| #define mbedtls_free free |
| #endif /* MBEDTLS_PLATFORM_C */ |
| |
| /* From RFC 8446: |
| * struct { |
| * select (Handshake.msg_type) { |
| * case client_hello: |
| * ProtocolVersion versions<2..254>; |
| * case server_hello: // and HelloRetryRequest |
| * ProtocolVersion selected_version; |
| * }; |
| * } SupportedVersions; |
| */ |
| static int ssl_tls13_parse_supported_versions_ext( mbedtls_ssl_context *ssl, |
| const unsigned char *buf, |
| const unsigned char *end ) |
| { |
| size_t versions_len; |
| int tls13_supported = 0; |
| int major_ver, minor_ver; |
| const unsigned char *p = buf; |
| const unsigned char *versions_end; |
| |
| MBEDTLS_SSL_CHK_BUF_READ_PTR( p, end, 1 ); |
| |
| versions_len = p[0]; |
| p += 1; |
| |
| MBEDTLS_SSL_CHK_BUF_READ_PTR( p, end, versions_len ); |
| if( versions_len % 2 != 0 ) |
| { |
| MBEDTLS_SSL_DEBUG_MSG( 1, ( "Invalid supported version list length %" MBEDTLS_PRINTF_SIZET, |
| versions_len ) ); |
| return( MBEDTLS_ERR_SSL_DECODE_ERROR ); |
| } |
| |
| versions_end = p + versions_len; |
| while( p < versions_end ) |
| { |
| mbedtls_ssl_read_version( &major_ver, &minor_ver, ssl->conf->transport, p ); |
| |
| /* In this implementation we only support TLS 1.3 and DTLS 1.3. */ |
| if( major_ver == MBEDTLS_SSL_MAJOR_VERSION_3 && |
| minor_ver == MBEDTLS_SSL_MINOR_VERSION_4 ) |
| { |
| tls13_supported = 1; |
| break; |
| } |
| |
| p += 2; |
| } |
| |
| if( tls13_supported == 0 ) |
| { |
| /* Here we only support TLS 1.3, we need report "bad protocol" if it |
| * doesn't support TLS 1.2. |
| */ |
| |
| MBEDTLS_SSL_DEBUG_MSG( 1, ( "TLS 1.3 is not supported by the client" ) ); |
| |
| MBEDTLS_SSL_PEND_FATAL_ALERT( MBEDTLS_SSL_ALERT_MSG_PROTOCOL_VERSION, |
| MBEDTLS_ERR_SSL_BAD_PROTOCOL_VERSION ); |
| return( MBEDTLS_ERR_SSL_BAD_PROTOCOL_VERSION ); |
| } |
| |
| MBEDTLS_SSL_DEBUG_MSG( 1, ( "Negotiated version. Supported is [%d:%d]", |
| major_ver, minor_ver ) ); |
| |
| ssl->major_ver = major_ver; |
| ssl->minor_ver = minor_ver; |
| return( 0 ); |
| } |
| |
| #if ( defined(MBEDTLS_ECDH_C) || defined(MBEDTLS_ECDSA_C) ) |
| /* This function parses the TLS 1.3 supported_groups extension and |
| * stores the received groups in ssl->handshake->curves. |
| * |
| * From RFC 8446: |
| * enum { |
| * ... (0xFFFF) |
| * } NamedGroup; |
| * struct { |
| * NamedGroup named_group_list<2..2^16-1>; |
| * } NamedGroupList; |
| */ |
| static int mbedtls_ssl_tls13_parse_supported_groups_ext( |
| mbedtls_ssl_context *ssl, |
| const unsigned char *buf, const unsigned char *end ) |
| { |
| |
| size_t named_group_list_len, curve_list_len; |
| const unsigned char *p = buf; |
| const mbedtls_ecp_curve_info *curve_info, **curves; |
| const unsigned char *extentions_end; |
| |
| MBEDTLS_SSL_DEBUG_BUF( 3, "supported_groups extension", p, end - buf ); |
| named_group_list_len = MBEDTLS_GET_UINT16_BE( p, 0 ); |
| p += 2; |
| MBEDTLS_SSL_CHK_BUF_READ_PTR( p, end, named_group_list_len ); |
| if( named_group_list_len % 2 != 0 ) |
| return( MBEDTLS_ERR_SSL_DECODE_ERROR ); |
| |
| /* At the moment, this can happen when receiving a second |
| * ClientHello after an HRR. We should properly reset the |
| * state upon receiving an HRR, in which case we should |
| * not observe handshake->curves already being allocated. */ |
| if( ssl->handshake->curves != NULL ) |
| { |
| mbedtls_free( ssl->handshake->curves ); |
| ssl->handshake->curves = NULL; |
| } |
| |
| /* Don't allow our peer to make us allocate too much memory, |
| * and leave room for a final 0 |
| */ |
| curve_list_len = named_group_list_len / 2 + 1; |
| if( curve_list_len > MBEDTLS_ECP_DP_MAX ) |
| curve_list_len = MBEDTLS_ECP_DP_MAX; |
| |
| if( ( curves = mbedtls_calloc( curve_list_len, sizeof( *curves ) ) ) == NULL ) |
| return( MBEDTLS_ERR_SSL_ALLOC_FAILED ); |
| |
| extentions_end = p + named_group_list_len; |
| ssl->handshake->curves = curves; |
| |
| while ( p < extentions_end && curve_list_len > 1 ) |
| { |
| uint16_t tls_grp_id = MBEDTLS_GET_UINT16_BE( p, 0 ); |
| curve_info = mbedtls_ecp_curve_info_from_tls_id( tls_grp_id ); |
| |
| /* mbedtls_ecp_curve_info_from_tls_id() uses the mbedtls_ecp_curve_info |
| * data structure (defined in ecp.c), which only includes the list of |
| * curves implemented. Hence, we only add curves that are also supported |
| * and implemented by the server. |
| */ |
| if( curve_info != NULL ) |
| { |
| *curves++ = curve_info; |
| MBEDTLS_SSL_DEBUG_MSG( 4, ( "supported curve: %s", curve_info->name ) ); |
| curve_list_len--; |
| } |
| |
| p += 2; |
| } |
| |
| return( 0 ); |
| |
| } |
| #endif /* MBEDTLS_ECDH_C || ( MBEDTLS_ECDSA_C */ |
| |
| #if defined(MBEDTLS_ECDH_C) |
| /* |
| * ssl_tls13_parse_key_shares_ext() verifies whether the information in the |
| * extension is correct and stores the provided key shares. Whether this is an |
| * acceptable key share depends on the selected ciphersuite. |
| * |
| * Possible return values are: |
| * - 0: Successful processing of the client provided key share extension. |
| * - MBEDTLS_ERR_SSL_HRR_REQUIRED: The key share provided by the client |
| * does not match a group supported by the server. A HelloRetryRequest will |
| * be needed. |
| * - Another negative return value for fatal errors. |
| */ |
| |
| static int ssl_tls13_parse_key_shares_ext( mbedtls_ssl_context *ssl, |
| const unsigned char *buf, |
| const unsigned char *end ) |
| { |
| int ret = 0; |
| unsigned char const *p = buf; |
| unsigned char const *extentions_end; |
| |
| size_t total_extensions_len, key_share_len; |
| int match_found = 0; |
| |
| /* From RFC 8446: |
| * |
| * struct { |
| * KeyShareEntry client_shares<0..2^16-1>; |
| * } KeyShareClientHello; |
| * |
| */ |
| |
| /* Read total legnth of KeyShareClientHello */ |
| MBEDTLS_SSL_CHK_BUF_READ_PTR( p, end, 2 ); |
| |
| total_extensions_len = MBEDTLS_GET_UINT16_BE( p, 0 ); |
| p += 2; |
| MBEDTLS_SSL_CHK_BUF_READ_PTR( p, end, total_extensions_len ); |
| |
| ssl->handshake->offered_group_id = 0; |
| extentions_end = p + total_extensions_len; |
| |
| /* We try to find a suitable key share entry and copy it to the |
| * handshake context. Later, we have to find out whether we can do |
| * something with the provided key share or whether we have to |
| * dismiss it and send a HelloRetryRequest message. |
| */ |
| |
| for( ; p < extentions_end; p += key_share_len ) |
| { |
| uint16_t group; |
| |
| /* |
| * struct { |
| * NamedGroup group; |
| * opaque key_exchange<1..2^16-1>; |
| * } KeyShareEntry; |
| */ |
| MBEDTLS_SSL_CHK_BUF_READ_PTR( p, extentions_end, 4 ); |
| |
| group = MBEDTLS_GET_UINT16_BE( p, 0 ); |
| p += 2; |
| |
| key_share_len = MBEDTLS_GET_UINT16_BE( p, 0 ); |
| p += 2; |
| |
| /* Continue parsing even if we have already found a match, |
| * for input validation purposes. |
| */ |
| if( match_found == 1 ) |
| continue; |
| |
| /* |
| * NamedGroup matching |
| * |
| * For now, we only support ECDHE groups, but e.g. |
| |
| * Type 1: ECDHE shares |
| * |
| * - Check if we recognize the group |
| * - Check if it's supported |
| */ |
| |
| if( mbedtls_ssl_tls13_named_group_is_ecdhe( group ) ) |
| { |
| const mbedtls_ecp_curve_info *curve_info = |
| mbedtls_ecp_curve_info_from_tls_id( group ); |
| if( curve_info == NULL ) |
| { |
| MBEDTLS_SSL_DEBUG_MSG( 1, ( "Invalid TLS curve group id" ) ); |
| return( MBEDTLS_ERR_SSL_INTERNAL_ERROR ); |
| } |
| |
| match_found = 1; |
| |
| MBEDTLS_SSL_DEBUG_MSG( 2, ( "ECDH curve: %s", curve_info->name ) ); |
| |
| ret = mbedtls_ssl_tls13_read_public_ecdhe_share( ssl, p, end - p ); |
| if( ret != 0 ) |
| return( ret ); |
| } |
| else |
| { |
| MBEDTLS_SSL_DEBUG_MSG( 4, ( "Unrecognized NamedGroup %u", |
| (unsigned) group ) ); |
| continue; |
| } |
| |
| ssl->handshake->offered_group_id = group; |
| } |
| |
| if( match_found == 0 ) |
| { |
| MBEDTLS_SSL_DEBUG_MSG( 1, ( "no matching key share" ) ); |
| return( MBEDTLS_ERR_SSL_HRR_REQUIRED ); |
| } |
| return( 0 ); |
| } |
| #endif /* MBEDTLS_ECDH_C */ |
| |
| #if defined(MBEDTLS_SSL_COOKIE_C) |
| static int ssl_tls13_parse_cookie_ext( mbedtls_ssl_context *ssl, |
| const unsigned char *buf, |
| const unsigned char *end ) |
| { |
| int ret = 0; |
| size_t cookie_len; |
| unsigned char const *p = buf; |
| |
| MBEDTLS_SSL_DEBUG_MSG( 3, ( "parse cookie extension" ) ); |
| |
| if( ssl->conf->f_cookie_check != NULL ) |
| { |
| MBEDTLS_SSL_CHK_BUF_READ_PTR( p, end, 2 ); |
| cookie_len = MBEDTLS_GET_UINT16_BE( p, 0 ); |
| p += 2; |
| |
| MBEDTLS_SSL_CHK_BUF_READ_PTR( p, end, cookie_len ); |
| |
| MBEDTLS_SSL_DEBUG_BUF( 3, "Received cookie", p, cookie_len ); |
| |
| if( ssl->conf->f_cookie_check( ssl->conf->p_cookie, |
| p, cookie_len, ssl->cli_id, |
| ssl->cli_id_len ) != 0 ) |
| { |
| MBEDTLS_SSL_DEBUG_MSG( 2, ( "cookie verification failed" ) ); |
| ret = MBEDTLS_ERR_SSL_HRR_REQUIRED; |
| } |
| else |
| { |
| MBEDTLS_SSL_DEBUG_MSG( 2, ( "cookie verification passed" ) ); |
| } |
| } |
| else |
| { |
| MBEDTLS_SSL_DEBUG_MSG( 2, ( "cookie verification skipped" ) ); |
| } |
| |
| return( ret ); |
| } |
| #endif /* MBEDTLS_SSL_COOKIE_C */ |
| |
| /* |
| * |
| * STATE HANDLING: ClientHello |
| * |
| * There are three possible classes of outcomes when parsing the CH: |
| * |
| * 1) The CH was well-formed and matched the server's configuration. |
| * |
| * In this case, the server progresses to sending its ServerHello. |
| * |
| * 2) The CH was well-formed but didn't match the server's configuration. |
| * |
| * For example, the client might not have offered a key share which |
| * the server supports, or the server might require a cookie. |
| * |
| * In this case, the server sends a HelloRetryRequest. |
| * |
| * 3) The CH was ill-formed |
| * |
| * In this case, we abort the handshake. |
| * |
| */ |
| |
| /* |
| * Overview |
| */ |
| |
| /* Main entry point from the state machine; orchestrates the otherfunctions. */ |
| static int ssl_tls13_process_client_hello( mbedtls_ssl_context *ssl ); |
| |
| static int ssl_tls13_parse_client_hello( mbedtls_ssl_context *ssl, |
| const unsigned char *buf, |
| const unsigned char *end ); |
| |
| /* Update the handshake state machine */ |
| static int ssl_tls13_postprocess_client_hello( mbedtls_ssl_context *ssl, |
| int hrr_required ); |
| |
| /* |
| * Implementation |
| */ |
| |
| #define SSL_CLIENT_HELLO_OK 0 |
| #define SSL_CLIENT_HELLO_HRR_REQUIRED 1 |
| |
| static int ssl_tls13_process_client_hello( mbedtls_ssl_context *ssl ) |
| { |
| |
| int ret = 0; |
| int hrr_required = SSL_CLIENT_HELLO_OK; |
| unsigned char* buf = NULL; |
| size_t buflen = 0; |
| MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> parse client hello" ) ); |
| |
| ssl->major_ver = MBEDTLS_SSL_MAJOR_VERSION_3; |
| MBEDTLS_SSL_PROC_CHK( mbedtls_ssl_tls13_fetch_handshake_msg( |
| ssl, MBEDTLS_SSL_HS_CLIENT_HELLO, |
| &buf, &buflen ) ); |
| |
| MBEDTLS_SSL_PROC_CHK_NEG( ssl_tls13_parse_client_hello( ssl, buf, |
| buf + buflen ) ); |
| hrr_required = ret; |
| |
| MBEDTLS_SSL_DEBUG_MSG( 1, ( "postprocess" ) ); |
| MBEDTLS_SSL_PROC_CHK( ssl_tls13_postprocess_client_hello( ssl, |
| hrr_required ) ); |
| |
| cleanup: |
| |
| MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= parse client hello" ) ); |
| return( ret ); |
| } |
| |
| static void ssl_tls13_debug_print_client_hello_exts( mbedtls_ssl_context *ssl ) |
| { |
| ((void) ssl); |
| |
| MBEDTLS_SSL_DEBUG_MSG( 3, ( "Supported Extensions:" ) ); |
| MBEDTLS_SSL_DEBUG_MSG( 3, ( "- KEY_SHARE_EXTENSION ( %s )", |
| ( ( ssl->handshake->extensions_present & MBEDTLS_SSL_EXT_KEY_SHARE ) > 0 ) ? |
| "TRUE" : "FALSE" ) ); |
| MBEDTLS_SSL_DEBUG_MSG( 3, ( "- PSK_KEY_EXCHANGE_MODES_EXTENSION ( %s )", |
| ( ( ssl->handshake->extensions_present & MBEDTLS_SSL_EXT_PSK_KEY_EXCHANGE_MODES ) > 0 ) ? |
| "TRUE" : "FALSE" ) ); |
| MBEDTLS_SSL_DEBUG_MSG( 3, ( "- PRE_SHARED_KEY_EXTENSION ( %s )", |
| ( ( ssl->handshake->extensions_present & MBEDTLS_SSL_EXT_PRE_SHARED_KEY ) > 0 ) ? |
| "TRUE" : "FALSE" ) ); |
| MBEDTLS_SSL_DEBUG_MSG( 3, ( "- SIGNATURE_ALGORITHM_EXTENSION ( %s )", |
| ( ( ssl->handshake->extensions_present & MBEDTLS_SSL_EXT_SIG_ALG ) > 0 ) ? |
| "TRUE" : "FALSE" ) ); |
| MBEDTLS_SSL_DEBUG_MSG( 3, ( "- SUPPORTED_GROUPS_EXTENSION ( %s )", |
| ( ( ssl->handshake->extensions_present & MBEDTLS_SSL_EXT_SUPPORTED_GROUPS ) >0 ) ? |
| "TRUE" : "FALSE" ) ); |
| MBEDTLS_SSL_DEBUG_MSG( 3, ( "- SUPPORTED_VERSION_EXTENSION ( %s )", |
| ( ( ssl->handshake->extensions_present & MBEDTLS_SSL_EXT_SUPPORTED_VERSIONS ) > 0 ) ? |
| "TRUE" : "FALSE" ) ); |
| #if defined ( MBEDTLS_SSL_SERVER_NAME_INDICATION ) |
| MBEDTLS_SSL_DEBUG_MSG( 3, ( "- SERVERNAME_EXTENSION ( %s )", |
| ( ( ssl->handshake->extensions_present & MBEDTLS_SSL_EXT_SERVERNAME ) > 0 ) ? |
| "TRUE" : "FALSE" ) ); |
| #endif /* MBEDTLS_SSL_SERVER_NAME_INDICATION */ |
| #if defined ( MBEDTLS_SSL_COOKIE_C ) |
| MBEDTLS_SSL_DEBUG_MSG( 3, ( "- COOKIE_EXTENSION ( %s )", |
| ( ( ssl->handshake->extensions_present & MBEDTLS_SSL_EXT_COOKIE ) >0 ) ? |
| "TRUE" : "FALSE" ) ); |
| #endif /* MBEDTLS_SSL_COOKIE_C */ |
| } |
| |
| static int ssl_tls13_client_hello_has_exts( mbedtls_ssl_context *ssl, |
| int ext_id_mask ) |
| { |
| int masked = ssl->handshake->extensions_present & ext_id_mask; |
| return( masked == ext_id_mask ); |
| } |
| |
| static int ssl_tls13_client_hello_has_cert_extensions( mbedtls_ssl_context *ssl ) |
| { |
| return( ssl_tls13_client_hello_has_exts( ssl, |
| MBEDTLS_SSL_EXT_SUPPORTED_GROUPS | |
| MBEDTLS_SSL_EXT_KEY_SHARE | |
| MBEDTLS_SSL_EXT_SIG_ALG ) ); |
| } |
| |
| static int ssl_tls13_check_certificate_key_exchange( mbedtls_ssl_context *ssl ) |
| { |
| if( !mbedtls_ssl_conf_tls13_ephemeral_enabled( ssl ) ) |
| return( 0 ); |
| |
| if( !ssl_tls13_client_hello_has_cert_extensions( ssl ) ) |
| return( 0 ); |
| |
| ssl->handshake->tls13_kex_modes = MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_EPHEMERAL; |
| return( 1 ); |
| } |
| |
| /* |
| * Structure of this message: |
| * |
| * uint16 ProtocolVersion; |
| * opaque Random[32]; |
| * |
| * uint8 CipherSuite[2]; // Cryptographic suite selector |
| * |
| * struct { |
| * ProtocolVersion legacy_version = 0x0303; // TLS v1.2 |
| * Random random; |
| * opaque legacy_session_id<0..32>; |
| * CipherSuite cipher_suites<2..2^16-2>; |
| * opaque legacy_compression_methods<1..2^8-1>; |
| * Extension extensions<8..2^16-1>; |
| * } ClientHello; |
| */ |
| static int ssl_tls13_parse_client_hello( mbedtls_ssl_context *ssl, |
| const unsigned char *buf, |
| const unsigned char *end ) |
| { |
| int ret; |
| size_t i, j; |
| size_t legacy_session_id_len; |
| size_t cipher_suites_len; |
| size_t extensions_len; |
| const unsigned char *ciph_offset; |
| const unsigned char *p = buf; |
| const unsigned char *extensions_end; |
| |
| const int* ciphersuites; |
| const mbedtls_ssl_ciphersuite_t* ciphersuite_info; |
| |
| int hrr_required = 0; |
| |
| ssl->handshake->extensions_present = MBEDTLS_SSL_EXT_NONE; |
| |
| /* |
| * ClientHello layer: |
| * 0 . 1 protocol version |
| * 2 . 33 random bytes ( starting with 4 bytes of Unix time ) |
| * 34 . 34 session id length ( 1 byte ) |
| * 35 . 34+x session id |
| * 35+x . 35+x DTLS only: cookie length ( 1 byte ) |
| * 36+x . .. DTLS only: cookie |
| * .. . .. ciphersuite list length ( 2 bytes ) |
| * .. . .. ciphersuite list |
| * .. . .. compression alg. list length ( 1 byte ) |
| * .. . .. compression alg. list |
| * .. . .. extensions length ( 2 bytes, optional ) |
| * .. . .. extensions ( optional ) |
| */ |
| |
| /* Needs to be updated due to mandatory extensions |
| * Minimal length ( with everything empty and extensions ommitted ) is |
| * 2 + 32 + 1 + 2 + 1 = 38 bytes. Check that first, so that we can |
| * read at least up to session id length without worrying. |
| */ |
| MBEDTLS_SSL_CHK_BUF_READ_PTR( p, end, 38 ); |
| |
| /* ... |
| * ProtocolVersion legacy_version = 0x0303; // TLS 1.2 |
| * ... |
| * with ProtocolVersion defined as: |
| * uint16 ProtocolVersion; |
| */ |
| if( !( p[0] == MBEDTLS_SSL_MAJOR_VERSION_3 && |
| p[1] == MBEDTLS_SSL_MINOR_VERSION_3 ) ) |
| { |
| MBEDTLS_SSL_DEBUG_MSG( 1, ( "Unsupported version of TLS." ) ); |
| MBEDTLS_SSL_PEND_FATAL_ALERT( MBEDTLS_SSL_ALERT_MSG_PROTOCOL_VERSION, |
| MBEDTLS_ERR_SSL_BAD_PROTOCOL_VERSION ); |
| ret = MBEDTLS_ERR_SSL_BAD_PROTOCOL_VERSION; |
| return ret; |
| } |
| p += 2; |
| |
| /* |
| * Save client random |
| */ |
| MBEDTLS_SSL_DEBUG_BUF( 3, "client hello, random bytes", |
| p, MBEDTLS_SERVER_HELLO_RANDOM_LEN ); |
| |
| memcpy( &ssl->handshake->randbytes[0], p, MBEDTLS_SERVER_HELLO_RANDOM_LEN ); |
| /* skip random bytes */ |
| p += MBEDTLS_SERVER_HELLO_RANDOM_LEN; |
| |
| /* |
| * Parse session ID |
| */ |
| legacy_session_id_len = p[0]; |
| p++; |
| |
| if( legacy_session_id_len > 32 ) |
| { |
| MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad client hello message" ) ); |
| return( MBEDTLS_ERR_SSL_DECODE_ERROR ); |
| } |
| |
| ssl->session_negotiate->id_len = legacy_session_id_len; |
| |
| /* Note that this field is echoed even if |
| * the client's value corresponded to a cached pre-TLS 1.3 session |
| * which the server has chosen not to resume. A client which |
| * receives a legacy_session_id_echo field that does not match what |
| * it sent in the ClientHello MUST abort the handshake with an |
| * "illegal_parameter" alert. |
| */ |
| MBEDTLS_SSL_DEBUG_MSG( 3, ( "client hello, session id length ( %" MBEDTLS_PRINTF_SIZET " )", legacy_session_id_len ) ); |
| MBEDTLS_SSL_DEBUG_BUF( 3, "client hello, session id", buf, legacy_session_id_len ); |
| |
| memcpy( &ssl->session_negotiate->id[0], p, legacy_session_id_len ); /* write session id */ |
| p += legacy_session_id_len; |
| |
| MBEDTLS_SSL_CHK_BUF_READ_PTR( p, end, 2 ); |
| cipher_suites_len = MBEDTLS_GET_UINT16_BE( p, 0 ); |
| p += 2; |
| |
| MBEDTLS_SSL_CHK_BUF_READ_PTR( p, end, cipher_suites_len ); |
| |
| /* store pointer to ciphersuite list */ |
| ciph_offset = p; |
| |
| MBEDTLS_SSL_DEBUG_BUF( 3, "client hello, ciphersuitelist", |
| p, cipher_suites_len ); |
| |
| /* skip ciphersuites for now */ |
| p += cipher_suites_len; |
| |
| /* ... |
| * uint8 legacy_compression_method = 0; |
| * ... |
| */ |
| MBEDTLS_SSL_CHK_BUF_READ_PTR( p, end, 1 ); |
| if( p[0] != 0 ) |
| { |
| MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad legacy compression method" ) ); |
| MBEDTLS_SSL_PEND_FATAL_ALERT( MBEDTLS_SSL_ALERT_MSG_ILLEGAL_PARAMETER, |
| MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER ); |
| return ( MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER ); |
| } |
| p++; |
| |
| /* |
| * Check the extension length |
| */ |
| MBEDTLS_SSL_CHK_BUF_READ_PTR( p, end, 2 ); |
| |
| extensions_len = MBEDTLS_GET_UINT16_BE( p, 0 ); |
| p += 2; |
| extensions_end = p + extensions_len; |
| MBEDTLS_SSL_CHK_BUF_READ_PTR( p, end, extensions_len ); |
| |
| MBEDTLS_SSL_DEBUG_BUF( 3, "client hello extensions", p, extensions_len ); |
| |
| while( p < extensions_end ) |
| { |
| unsigned int extension_type; |
| size_t extension_data_len; |
| const unsigned char *extension_data_end; |
| |
| MBEDTLS_SSL_CHK_BUF_READ_PTR( p, end, 4 ); |
| extension_type = MBEDTLS_GET_UINT16_BE( p, 0 ); |
| extension_data_len = MBEDTLS_GET_UINT16_BE( p, 2 ); |
| p += 4; |
| |
| MBEDTLS_SSL_CHK_BUF_READ_PTR( p, extensions_end, extension_data_len ); |
| extension_data_end = p + extension_data_len; |
| |
| switch( extension_type ) |
| { |
| #if defined(MBEDTLS_SSL_COOKIE_C) |
| case MBEDTLS_TLS_EXT_COOKIE: |
| MBEDTLS_SSL_DEBUG_MSG( 3, ( "found cookie extension" ) ); |
| |
| ret = ssl_tls13_parse_cookie_ext( ssl, p, |
| extension_data_end ); |
| |
| /* if cookie verification failed then we return a hello retry |
| * message, or return success and set cookie extension present |
| */ |
| if( ret == MBEDTLS_ERR_SSL_HRR_REQUIRED ) |
| { |
| hrr_required = 1; |
| } |
| else if( ret == 0 ) |
| { |
| ssl->handshake->extensions_present |= MBEDTLS_SSL_EXT_COOKIE; |
| } |
| break; |
| #endif /* MBEDTLS_SSL_COOKIE_C */ |
| |
| #if defined(MBEDTLS_ECDH_C) || defined(MBEDTLS_ECDSA_C) |
| case MBEDTLS_TLS_EXT_SUPPORTED_GROUPS: |
| MBEDTLS_SSL_DEBUG_MSG( 3, ( "found supported group extension" ) ); |
| |
| /* Supported Groups Extension |
| * |
| * When sent by the client, the "supported_groups" extension |
| * indicates the named groups which the client supports, |
| * ordered from most preferred to least preferred. |
| */ |
| ret = mbedtls_ssl_tls13_parse_supported_groups_ext( ssl, p, |
| extension_data_end ); |
| if( ret != 0 ) |
| { |
| MBEDTLS_SSL_DEBUG_RET( 1, |
| "mbedtls_ssl_parse_supported_groups_ext", ret ); |
| return( ret ); |
| } |
| |
| ssl->handshake->extensions_present |= MBEDTLS_SSL_EXT_SUPPORTED_GROUPS; |
| break; |
| #endif /* MBEDTLS_ECDH_C || MBEDTLS_ECDSA_C */ |
| |
| #if defined(MBEDTLS_ECDH_C) |
| case MBEDTLS_TLS_EXT_KEY_SHARE: |
| MBEDTLS_SSL_DEBUG_MSG( 3, ( "found key share extension" ) ); |
| |
| /* |
| * Key Share Extension |
| * |
| * When sent by the client, the "key_share" extension |
| * contains the endpoint's cryptographic parameters for |
| * ECDHE/DHE key establishment methods. |
| */ |
| ret = ssl_tls13_parse_key_shares_ext( ssl, p, extension_data_end ); |
| if( ret == MBEDTLS_ERR_SSL_HRR_REQUIRED ) |
| { |
| hrr_required = 1; |
| ret = 0; |
| } |
| |
| if( ret != 0 ) |
| return( ret ); |
| |
| ssl->handshake->extensions_present |= MBEDTLS_SSL_EXT_KEY_SHARE; |
| break; |
| #endif /* MBEDTLS_ECDH_C */ |
| |
| case MBEDTLS_TLS_EXT_SUPPORTED_VERSIONS: |
| MBEDTLS_SSL_DEBUG_MSG( 3, ( "found supported versions extension" ) ); |
| |
| ret = ssl_tls13_parse_supported_versions_ext( |
| ssl, p, extension_data_end ); |
| if( ret != 0 ) |
| { |
| MBEDTLS_SSL_DEBUG_RET( 1, |
| ( "ssl_tls13_parse_supported_versions_ext" ), ret ); |
| return( ret ); |
| } |
| ssl->handshake->extensions_present |= MBEDTLS_SSL_EXT_SUPPORTED_VERSIONS; |
| break; |
| |
| #if defined(MBEDTLS_KEY_EXCHANGE_WITH_CERT_ENABLED) |
| case MBEDTLS_TLS_EXT_SIG_ALG: |
| MBEDTLS_SSL_DEBUG_MSG( 3, ( "found signature_algorithms extension" ) ); |
| |
| ret = mbedtls_ssl_tls13_parse_sig_alg_ext( ssl, p, |
| extension_data_end ); |
| if( ret != 0 ) |
| { |
| MBEDTLS_SSL_DEBUG_MSG( 1, |
| ( "ssl_parse_supported_signature_algorithms_server_ext ( %d )", |
| ret ) ); |
| return( ret ); |
| } |
| ssl->handshake->extensions_present |= MBEDTLS_SSL_EXT_SIG_ALG; |
| break; |
| #endif /* MBEDTLS_KEY_EXCHANGE_WITH_CERT_ENABLED */ |
| |
| default: |
| MBEDTLS_SSL_DEBUG_MSG( 3, |
| ( "unknown extension found: %ud ( ignoring )", |
| extension_type ) ); |
| } |
| |
| p += extension_data_len; |
| } |
| |
| /* Update checksum with either |
| * - The entire content of the CH message, if no PSK extension is present |
| * - The content up to but excluding the PSK extension, if present. |
| */ |
| mbedtls_ssl_add_hs_msg_to_checksum( ssl, MBEDTLS_SSL_HS_SERVER_HELLO, |
| buf, p - buf ); |
| /* |
| * Search for a matching ciphersuite |
| */ |
| ciphersuites = ssl->conf->ciphersuite_list; |
| ciphersuite_info = NULL; |
| for ( j = 0, p = ciph_offset; j < cipher_suites_len; j += 2, p += 2 ) |
| { |
| for ( i = 0; ciphersuites[i] != 0; i++ ) |
| { |
| if( p[0] != ( ( ciphersuites[i] >> 8 ) & 0xFF ) || |
| p[1] != ( ( ciphersuites[i] ) & 0xFF ) ) |
| continue; |
| |
| ciphersuite_info = mbedtls_ssl_ciphersuite_from_id( |
| ciphersuites[i] ); |
| |
| if( ciphersuite_info == NULL ) |
| { |
| MBEDTLS_SSL_DEBUG_MSG( |
| 1, |
| ( "mbedtls_ssl_ciphersuite_from_id: should never happen" ) ); |
| return( MBEDTLS_ERR_SSL_INTERNAL_ERROR ); |
| } |
| |
| goto have_ciphersuite; |
| |
| } |
| } |
| |
| return( MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE ); |
| |
| have_ciphersuite: |
| |
| MBEDTLS_SSL_DEBUG_MSG( 2, ( "selected ciphersuite: %s", |
| ciphersuite_info->name ) ); |
| |
| ssl->session_negotiate->ciphersuite = ciphersuites[i]; |
| ssl->handshake->ciphersuite_info = ciphersuite_info; |
| |
| /* List all the extensions we have received */ |
| ssl_tls13_debug_print_client_hello_exts( ssl ); |
| |
| /* |
| * Determine the key exchange algorithm to use. |
| * There are three types of key exchanges supported in TLS 1.3: |
| * - (EC)DH with ECDSA, |
| * - (EC)DH with PSK, |
| * - plain PSK. |
| * |
| * The PSK-based key exchanges may additionally be used with 0-RTT. |
| * |
| * Our built-in order of preference is |
| * 1 ) Plain PSK Mode |
| * 2 ) (EC)DHE-PSK Mode |
| * 3 ) Certificate Mode |
| */ |
| |
| if( !ssl_tls13_check_certificate_key_exchange( ssl ) ) |
| { |
| MBEDTLS_SSL_DEBUG_MSG( |
| 1, |
| ( "ClientHello message misses mandatory extensions." ) ); |
| MBEDTLS_SSL_PEND_FATAL_ALERT( MBEDTLS_SSL_ALERT_MSG_MISSING_EXTENSION , |
| MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER ); |
| return( MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER ); |
| } |
| |
| #if defined(MBEDTLS_SSL_COOKIE_C) |
| /* If we failed to see a cookie extension, and we required it through the |
| * configuration settings ( rr_config ), then we need to send a HRR msg. |
| * Conceptually, this is similiar to having received a cookie that failed |
| * the verification check. |
| */ |
| if( ( ssl->conf->rr_config == MBEDTLS_SSL_FORCE_RR_CHECK_ON ) && |
| !( ssl->handshake->extensions_present & MBEDTLS_SSL_EXT_COOKIE ) ) |
| { |
| MBEDTLS_SSL_DEBUG_MSG( |
| 2, |
| ( "Cookie extension missing. Need to send a HRR." ) ); |
| hrr_required = 1; |
| } |
| #endif /* MBEDTLS_SSL_COOKIE_C */ |
| |
| if( hrr_required == 1 ) |
| return( SSL_CLIENT_HELLO_HRR_REQUIRED ); |
| |
| return( 0 ); |
| } |
| |
| static int ssl_tls13_postprocess_client_hello( mbedtls_ssl_context* ssl, |
| int hrr_required ) |
| { |
| int ret = 0; |
| |
| if( ssl->handshake->hello_retry_requests_sent == 0 && |
| ssl->conf->rr_config == MBEDTLS_SSL_FORCE_RR_CHECK_ON ) |
| { |
| hrr_required = SSL_CLIENT_HELLO_HRR_REQUIRED; |
| } |
| |
| if( hrr_required == SSL_CLIENT_HELLO_HRR_REQUIRED ) |
| { |
| /* |
| * Create stateless transcript hash for HRR |
| */ |
| MBEDTLS_SSL_DEBUG_MSG( 4, ( "Reset transcript for HRR" ) ); |
| ret = mbedtls_ssl_reset_transcript_for_hrr( ssl ); |
| if( ret != 0 ) |
| { |
| MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_reset_transcript_for_hrr", |
| ret ); |
| return( ret ); |
| } |
| mbedtls_ssl_session_reset_msg_layer( ssl, 0 ); |
| |
| /* Transmit Hello Retry Request */ |
| mbedtls_ssl_handshake_set_state( ssl, MBEDTLS_SSL_HELLO_RETRY_REQUEST ); |
| return( 0 ); |
| } |
| |
| ret = mbedtls_ssl_tls13_key_schedule_stage_early( ssl ); |
| if( ret != 0 ) |
| { |
| MBEDTLS_SSL_DEBUG_RET( 1, |
| "mbedtls_ssl_tls1_3_key_schedule_stage_early", ret ); |
| return( ret ); |
| } |
| |
| mbedtls_ssl_handshake_set_state( ssl, MBEDTLS_SSL_SERVER_HELLO ); |
| return( 0 ); |
| |
| } |
| |
| /* |
| * TLS and DTLS 1.3 State Maschine -- server side |
| */ |
| int mbedtls_ssl_tls13_handshake_server_step( mbedtls_ssl_context *ssl ) |
| { |
| int ret = 0; |
| |
| if( ssl->state == MBEDTLS_SSL_HANDSHAKE_OVER || ssl->handshake == NULL ) |
| return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA ); |
| |
| MBEDTLS_SSL_DEBUG_MSG( 2, ( "tls13 server state: %s(%d)", |
| mbedtls_ssl_states_str( ssl->state ), |
| ssl->state ) ); |
| |
| if( ( ret = mbedtls_ssl_flush_output( ssl ) ) != 0 ) |
| return( ret ); |
| |
| switch( ssl->state ) |
| { |
| /* start state */ |
| case MBEDTLS_SSL_HELLO_REQUEST: |
| ssl->handshake->hello_retry_requests_sent = 0; |
| mbedtls_ssl_handshake_set_state( ssl, MBEDTLS_SSL_CLIENT_HELLO ); |
| |
| break; |
| |
| /* ----- READ CLIENT HELLO ----*/ |
| |
| case MBEDTLS_SSL_CLIENT_HELLO: |
| |
| ret = ssl_tls13_process_client_hello( ssl ); |
| if( ret != 0 ) |
| MBEDTLS_SSL_DEBUG_RET( 1, "ssl_tls13_process_client_hello", ret ); |
| |
| break; |
| |
| case MBEDTLS_SSL_HANDSHAKE_WRAPUP: |
| MBEDTLS_SSL_DEBUG_MSG( 2, ( "handshake: done" ) ); |
| |
| MBEDTLS_SSL_DEBUG_MSG( 1, ( "Switch to application keys for all traffic" ) ); |
| |
| mbedtls_ssl_set_inbound_transform ( ssl, ssl->transform_application ); |
| mbedtls_ssl_set_outbound_transform( ssl, ssl->transform_application ); |
| |
| mbedtls_ssl_tls13_handshake_wrapup( ssl ); |
| mbedtls_ssl_handshake_set_state( ssl, MBEDTLS_SSL_SERVER_NEW_SESSION_TICKET ); |
| |
| break; |
| |
| default: |
| MBEDTLS_SSL_DEBUG_MSG( 1, ( "invalid state %d", ssl->state ) ); |
| return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA ); |
| } |
| |
| return( ret ); |
| } |
| |
| #endif /* MBEDTLS_SSL_SRV_C && MBEDTLS_SSL_PROTO_TLS1_3 */ |