/* * TLS 1.3 client-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. * * This file is part of mbed TLS ( https://tls.mbed.org ) */ #include "common.h" #if defined(MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL) #if defined(MBEDTLS_SSL_CLI_C) #include #include "mbedtls/debug.h" #include "mbedtls/error.h" #include "mbedtls/platform.h" #include "ssl_misc.h" #include "ecdh_misc.h" #include "ssl_tls13_keys.h" /* Write extensions */ /* * ssl_tls13_write_supported_versions_ext(): * * struct { * ProtocolVersion versions<2..254>; * } SupportedVersions; */ static int ssl_tls13_write_supported_versions_ext( mbedtls_ssl_context *ssl, unsigned char *buf, unsigned char *end, size_t *olen ) { unsigned char *p = buf; *olen = 0; MBEDTLS_SSL_DEBUG_MSG( 3, ( "client hello, adding supported versions extension" ) ); /* Check if we have space to write the extension: * - extension_type (2 bytes) * - extension_data_length (2 bytes) * - versions_length (1 byte ) * - versions (2 bytes) */ MBEDTLS_SSL_CHK_BUF_PTR( p, end, 7 ); /* Write extension_type */ MBEDTLS_PUT_UINT16_BE( MBEDTLS_TLS_EXT_SUPPORTED_VERSIONS, p, 0 ); /* Write extension_data_length */ MBEDTLS_PUT_UINT16_BE( 3, p, 2 ); p += 4; /* Length of versions */ *p++ = 0x2; /* Write values of supported versions. * * They are defined by the configuration. * * Currently, only one version is advertised. */ mbedtls_ssl_write_version( ssl->conf->max_major_ver, ssl->conf->max_minor_ver, ssl->conf->transport, p ); MBEDTLS_SSL_DEBUG_MSG( 3, ( "supported version: [%d:%d]", ssl->conf->max_major_ver, ssl->conf->max_minor_ver ) ); *olen = 7; return( 0 ); } static int ssl_tls13_parse_supported_versions_ext( mbedtls_ssl_context *ssl, const unsigned char *buf, const unsigned char *end ) { ((void) ssl); MBEDTLS_SSL_CHK_BUF_READ_PTR( buf, end, 2); if( buf[0] != MBEDTLS_SSL_MAJOR_VERSION_3 || buf[1] != MBEDTLS_SSL_MINOR_VERSION_4 ) { MBEDTLS_SSL_DEBUG_MSG( 1, ( "unexpected version" ) ); MBEDTLS_SSL_PEND_FATAL_ALERT( MBEDTLS_SSL_ALERT_MSG_ILLEGAL_PARAMETER, MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER); return( MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER ); } return( 0 ); } #if defined(MBEDTLS_KEY_EXCHANGE_WITH_CERT_ENABLED) /* * Functions for writing supported_groups extension. * * Stucture of supported_groups: * enum { * secp256r1(0x0017), secp384r1(0x0018), secp521r1(0x0019), * x25519(0x001D), x448(0x001E), * ffdhe2048(0x0100), ffdhe3072(0x0101), ffdhe4096(0x0102), * ffdhe6144(0x0103), ffdhe8192(0x0104), * ffdhe_private_use(0x01FC..0x01FF), * ecdhe_private_use(0xFE00..0xFEFF), * (0xFFFF) * } NamedGroup; * struct { * NamedGroup named_group_list<2..2^16-1>; * } NamedGroupList; */ #if defined(MBEDTLS_ECDH_C) /* * In versions of TLS prior to TLS 1.3, this extension was named * 'elliptic_curves' and only contained elliptic curve groups. */ static int ssl_tls13_write_named_group_list_ecdhe( mbedtls_ssl_context *ssl, unsigned char *buf, unsigned char *end, size_t *olen ) { unsigned char *p = buf; *olen = 0; if( ssl->conf->curve_list == NULL ) return( MBEDTLS_ERR_SSL_BAD_CONFIG ); for ( const mbedtls_ecp_group_id *grp_id = ssl->conf->curve_list; *grp_id != MBEDTLS_ECP_DP_NONE; grp_id++ ) { const mbedtls_ecp_curve_info *info; info = mbedtls_ecp_curve_info_from_grp_id( *grp_id ); if( info == NULL ) continue; if( !mbedtls_ssl_tls13_named_group_is_ecdhe( info->tls_id ) ) continue; MBEDTLS_SSL_CHK_BUF_PTR( p, end, 2); MBEDTLS_PUT_UINT16_BE( info->tls_id, p, 0 ); p += 2; MBEDTLS_SSL_DEBUG_MSG( 3, ( "NamedGroup: %s ( %x )", mbedtls_ecp_curve_info_from_tls_id( info->tls_id )->name, info->tls_id ) ); } *olen = p - buf; return( 0 ); } #else static int ssl_tls13_write_named_group_list_ecdhe( mbedtls_ssl_context *ssl, unsigned char *buf, unsigned char *end, size_t *olen ) { ((void) ssl); ((void) buf); ((void) end); *olen = 0; return( MBEDTLS_ERR_SSL_FEATURE_UNAVAILABLE ); } #endif /* MBEDTLS_ECDH_C */ static int ssl_tls13_write_named_group_list_dhe( mbedtls_ssl_context *ssl, unsigned char *buf, unsigned char *end, size_t *olen ) { ((void) ssl); ((void) buf); ((void) end); *olen = 0; MBEDTLS_SSL_DEBUG_MSG( 3, ( "write_named_group_dhe is not implemented" ) ); return( MBEDTLS_ERR_SSL_FEATURE_UNAVAILABLE ); } static int ssl_tls13_write_supported_groups_ext( mbedtls_ssl_context *ssl, unsigned char *buf, unsigned char *end, size_t *olen ) { unsigned char *p = buf ; unsigned char *named_group_list_ptr; /* Start of named_group_list */ size_t named_group_list_len; /* Length of named_group_list */ size_t output_len = 0; int ret_ecdhe, ret_dhe; *olen = 0; if( !mbedtls_ssl_conf_tls13_some_ephemeral_enabled( ssl ) ) return( 0 ); MBEDTLS_SSL_DEBUG_MSG( 3, ( "client hello, adding supported_groups extension" ) ); /* Check if we have space for header and length fields: * - extension_type (2 bytes) * - extension_data_length (2 bytes) * - named_group_list_length (2 bytes) */ MBEDTLS_SSL_CHK_BUF_PTR( p, end, 6 ); p += 6; named_group_list_ptr = p; ret_ecdhe = ssl_tls13_write_named_group_list_ecdhe( ssl, p, end, &output_len ); if( ret_ecdhe != 0 ) { MBEDTLS_SSL_DEBUG_RET( 1, "ssl_tls13_write_named_group_list_ecdhe", ret_ecdhe ); } p += output_len; ret_dhe = ssl_tls13_write_named_group_list_dhe( ssl, p, end, &output_len ); if( ret_dhe != 0 ) { MBEDTLS_SSL_DEBUG_RET( 1, "ssl_tls13_write_named_group_list_dhe", ret_dhe ); } p += output_len; /* Both ECDHE and DHE failed. */ if( ret_ecdhe != 0 && ret_dhe != 0 ) { MBEDTLS_SSL_DEBUG_MSG( 1, ( "Both ECDHE and DHE groups are fail. " ) ); return( MBEDTLS_ERR_SSL_INTERNAL_ERROR ); } /* Length of named_group_list*/ named_group_list_len = p - named_group_list_ptr; if( named_group_list_len == 0 ) { MBEDTLS_SSL_DEBUG_MSG( 1, ( "No group available." ) ); return( MBEDTLS_ERR_SSL_INTERNAL_ERROR ); } /* Write extension_type */ MBEDTLS_PUT_UINT16_BE( MBEDTLS_TLS_EXT_SUPPORTED_GROUPS, buf, 0 ); /* Write extension_data_length */ MBEDTLS_PUT_UINT16_BE( named_group_list_len + 2, buf, 2 ); /* Write length of named_group_list */ MBEDTLS_PUT_UINT16_BE( named_group_list_len, buf, 4 ); MBEDTLS_SSL_DEBUG_BUF( 3, "Supported groups extension", buf + 4, named_group_list_len + 2 ); *olen = p - buf; ssl->handshake->extensions_present |= MBEDTLS_SSL_EXT_SUPPORTED_GROUPS; return( 0 ); } /* * Functions for writing key_share extension. */ #if defined(MBEDTLS_ECDH_C) static int ssl_tls13_generate_and_write_ecdh_key_exchange( mbedtls_ssl_context *ssl, uint16_t named_group, unsigned char *buf, unsigned char *end, size_t *olen ) { int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; const mbedtls_ecp_curve_info *curve_info = mbedtls_ecp_curve_info_from_tls_id( named_group ); if( curve_info == NULL ) return( MBEDTLS_ERR_SSL_INTERNAL_ERROR ); MBEDTLS_SSL_DEBUG_MSG( 3, ( "offer curve %s", curve_info->name ) ); if( ( ret = mbedtls_ecdh_setup_no_everest( &ssl->handshake->ecdh_ctx, curve_info->grp_id ) ) != 0 ) { MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ecdh_setup_no_everest", ret ); return( ret ); } ret = mbedtls_ecdh_tls13_make_params( &ssl->handshake->ecdh_ctx, olen, buf, end - buf, ssl->conf->f_rng, ssl->conf->p_rng ); if( ret != 0 ) { MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ecdh_tls13_make_params", ret ); return( ret ); } MBEDTLS_SSL_DEBUG_ECDH( 3, &ssl->handshake->ecdh_ctx, MBEDTLS_DEBUG_ECDH_Q ); return( 0 ); } #endif /* MBEDTLS_ECDH_C */ static int ssl_tls13_get_default_group_id( mbedtls_ssl_context *ssl, uint16_t *group_id ) { int ret = MBEDTLS_ERR_SSL_FEATURE_UNAVAILABLE; #if defined(MBEDTLS_ECDH_C) /* Pick first available ECDHE group compatible with TLS 1.3 */ if( ssl->conf->curve_list == NULL ) return( MBEDTLS_ERR_SSL_BAD_CONFIG ); for ( const mbedtls_ecp_group_id *grp_id = ssl->conf->curve_list; *grp_id != MBEDTLS_ECP_DP_NONE; grp_id++ ) { const mbedtls_ecp_curve_info *info; info = mbedtls_ecp_curve_info_from_grp_id( *grp_id ); if( info != NULL && mbedtls_ssl_tls13_named_group_is_ecdhe( info->tls_id ) ) { *group_id = info->tls_id; return( 0 ); } } #else ((void) ssl); ((void) group_id); #endif /* MBEDTLS_ECDH_C */ /* * Add DHE named groups here. * Pick first available DHE group compatible with TLS 1.3 */ return( ret ); } /* * ssl_tls13_write_key_share_ext * * Structure of key_share extension in ClientHello: * * struct { * NamedGroup group; * opaque key_exchange<1..2^16-1>; * } KeyShareEntry; * struct { * KeyShareEntry client_shares<0..2^16-1>; * } KeyShareClientHello; */ static int ssl_tls13_write_key_share_ext( mbedtls_ssl_context *ssl, unsigned char *buf, unsigned char *end, size_t *olen ) { unsigned char *p = buf; unsigned char *client_shares_ptr; /* Start of client_shares */ size_t client_shares_len; /* Length of client_shares */ uint16_t group_id; int ret = MBEDTLS_ERR_SSL_FEATURE_UNAVAILABLE; *olen = 0; if( !mbedtls_ssl_conf_tls13_some_ephemeral_enabled( ssl ) ) return( 0 ); /* Check if we have space for header and length fields: * - extension_type (2 bytes) * - extension_data_length (2 bytes) * - client_shares_length (2 bytes) */ MBEDTLS_SSL_CHK_BUF_PTR( p, end, 6 ); p += 6; MBEDTLS_SSL_DEBUG_MSG( 3, ( "client hello: adding key share extension" ) ); /* HRR could already have requested something else. */ group_id = ssl->handshake->offered_group_id; if( !mbedtls_ssl_tls13_named_group_is_ecdhe( group_id ) && !mbedtls_ssl_tls13_named_group_is_dhe( group_id ) ) { MBEDTLS_SSL_PROC_CHK( ssl_tls13_get_default_group_id( ssl, &group_id ) ); } /* * Dispatch to type-specific key generation function. * * So far, we're only supporting ECDHE. With the introduction * of PQC KEMs, we'll want to have multiple branches, one per * type of KEM, and dispatch to the corresponding crypto. And * only one key share entry is allowed. */ client_shares_ptr = p; #if defined(MBEDTLS_ECDH_C) if( mbedtls_ssl_tls13_named_group_is_ecdhe( group_id ) ) { /* Pointer to group */ unsigned char *group_ptr = p; /* Length of key_exchange */ size_t key_exchange_len; /* Check there is space for header of KeyShareEntry * - group (2 bytes) * - key_exchange_length (2 bytes) */ MBEDTLS_SSL_CHK_BUF_PTR( p, end, 4 ); p += 4; ret = ssl_tls13_generate_and_write_ecdh_key_exchange( ssl, group_id, p, end, &key_exchange_len ); p += key_exchange_len; if( ret != 0 ) return( ret ); /* Write group */ MBEDTLS_PUT_UINT16_BE( group_id, group_ptr, 0 ); /* Write key_exchange_length */ MBEDTLS_PUT_UINT16_BE( key_exchange_len, group_ptr, 2 ); } else #endif /* MBEDTLS_ECDH_C */ if( 0 /* other KEMs? */ ) { /* Do something */ } else return( MBEDTLS_ERR_SSL_INTERNAL_ERROR ); /* Length of client_shares */ client_shares_len = p - client_shares_ptr; if( client_shares_len == 0) { MBEDTLS_SSL_DEBUG_MSG( 1, ( "No key share defined." ) ); return( MBEDTLS_ERR_SSL_INTERNAL_ERROR ); } /* Write extension_type */ MBEDTLS_PUT_UINT16_BE( MBEDTLS_TLS_EXT_KEY_SHARE, buf, 0 ); /* Write extension_data_length */ MBEDTLS_PUT_UINT16_BE( client_shares_len + 2, buf, 2 ); /* Write client_shares_length */ MBEDTLS_PUT_UINT16_BE( client_shares_len, buf, 4 ); /* Update offered_group_id field */ ssl->handshake->offered_group_id = group_id; /* Output the total length of key_share extension. */ *olen = p - buf; MBEDTLS_SSL_DEBUG_BUF( 3, "client hello, key_share extension", buf, *olen ); ssl->handshake->extensions_present |= MBEDTLS_SSL_EXT_KEY_SHARE; cleanup: return( ret ); } #if defined(MBEDTLS_ECDH_C) static int ssl_tls13_check_ecdh_params( const mbedtls_ssl_context *ssl ) { const mbedtls_ecp_curve_info *curve_info; mbedtls_ecp_group_id grp_id; #if defined(MBEDTLS_ECDH_LEGACY_CONTEXT) grp_id = ssl->handshake->ecdh_ctx.grp.id; #else grp_id = ssl->handshake->ecdh_ctx.grp_id; #endif curve_info = mbedtls_ecp_curve_info_from_grp_id( grp_id ); if( curve_info == NULL ) { MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) ); return( MBEDTLS_ERR_SSL_INTERNAL_ERROR ); } MBEDTLS_SSL_DEBUG_MSG( 2, ( "ECDH curve: %s", curve_info->name ) ); if( mbedtls_ssl_check_curve( ssl, grp_id ) != 0 ) return( -1 ); MBEDTLS_SSL_DEBUG_ECDH( 3, &ssl->handshake->ecdh_ctx, MBEDTLS_DEBUG_ECDH_QP ); return( 0 ); } static int ssl_tls13_read_public_ecdhe_share( mbedtls_ssl_context *ssl, const unsigned char *buf, size_t buf_len ) { int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; ret = mbedtls_ecdh_tls13_read_public( &ssl->handshake->ecdh_ctx, buf, buf_len ); if( ret != 0 ) { MBEDTLS_SSL_DEBUG_RET( 1, ( "mbedtls_ecdh_tls13_read_public" ), ret ); MBEDTLS_SSL_PEND_FATAL_ALERT( MBEDTLS_SSL_ALERT_MSG_ILLEGAL_PARAMETER, MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER ); return( MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER ); } if( ssl_tls13_check_ecdh_params( ssl ) != 0 ) { MBEDTLS_SSL_DEBUG_MSG( 1, ( "ssl_tls13_check_ecdh_params() failed!" ) ); MBEDTLS_SSL_PEND_FATAL_ALERT( MBEDTLS_SSL_ALERT_MSG_ILLEGAL_PARAMETER, MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER ); return( MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER ); } return( 0 ); } #endif /* MBEDTLS_ECDH_C */ /* * ssl_tls13_parse_key_share_ext() * Parse key_share extension in Server Hello * * struct { * KeyShareEntry server_share; * } KeyShareServerHello; * struct { * NamedGroup group; * opaque key_exchange<1..2^16-1>; * } KeyShareEntry; */ static int ssl_tls13_parse_key_share_ext( mbedtls_ssl_context *ssl, const unsigned char *buf, const unsigned char *end ) { int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; const unsigned char *p = buf; uint16_t group, offered_group; /* ... * NamedGroup group; (2 bytes) * ... */ MBEDTLS_SSL_CHK_BUF_READ_PTR( p, end, 2 ); group = MBEDTLS_GET_UINT16_BE( p, 0 ); p += 2; /* Check that the chosen group matches the one we offered. */ offered_group = ssl->handshake->offered_group_id; if( offered_group != group ) { MBEDTLS_SSL_DEBUG_MSG( 1, ( "Invalid server key share, our group %u, their group %u", (unsigned) offered_group, (unsigned) group ) ); MBEDTLS_SSL_PEND_FATAL_ALERT( MBEDTLS_SSL_ALERT_MSG_HANDSHAKE_FAILURE, MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE ); return( MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE ); } #if defined(MBEDTLS_ECDH_C) if( mbedtls_ssl_tls13_named_group_is_ecdhe( group ) ) { /* Complete ECDHE key agreement */ ret = ssl_tls13_read_public_ecdhe_share( ssl, p, end - p ); if( ret != 0 ) return( ret ); } else #endif /* MBEDTLS_ECDH_C */ if( 0 /* other KEMs? */ ) { /* Do something */ } else return( MBEDTLS_ERR_SSL_INTERNAL_ERROR ); ssl->handshake->extensions_present |= MBEDTLS_SSL_EXT_KEY_SHARE; return( ret ); } #endif /* MBEDTLS_KEY_EXCHANGE_WITH_CERT_ENABLED */ /* Write cipher_suites * CipherSuite cipher_suites<2..2^16-2>; */ static int ssl_tls13_write_client_hello_cipher_suites( mbedtls_ssl_context *ssl, unsigned char *buf, unsigned char *end, size_t *olen ) { unsigned char *p = buf; const int *ciphersuite_list; unsigned char *cipher_suites_ptr; /* Start of the cipher_suites list */ size_t cipher_suites_len; *olen = 0 ; /* * Ciphersuite list * * This is a list of the symmetric cipher options supported by * the client, specifically the record protection algorithm * ( including secret key length ) and a hash to be used with * HKDF, in descending order of client preference. */ ciphersuite_list = ssl->conf->ciphersuite_list; /* Check there is space for the cipher suite list length (2 bytes). */ MBEDTLS_SSL_CHK_BUF_PTR( p, end, 2 ); p += 2; /* Write cipher_suites */ cipher_suites_ptr = p; for ( size_t i = 0; ciphersuite_list[i] != 0; i++ ) { int cipher_suite = ciphersuite_list[i]; const mbedtls_ssl_ciphersuite_t *ciphersuite_info; ciphersuite_info = mbedtls_ssl_ciphersuite_from_id( cipher_suite ); if( ciphersuite_info == NULL ) continue; if( !( MBEDTLS_SSL_MINOR_VERSION_4 >= ciphersuite_info->min_minor_ver && MBEDTLS_SSL_MINOR_VERSION_4 <= ciphersuite_info->max_minor_ver ) ) continue; MBEDTLS_SSL_DEBUG_MSG( 3, ( "client hello, add ciphersuite: %04x, %s", (unsigned int) cipher_suite, ciphersuite_info->name ) ); /* Check there is space for the cipher suite identifier (2 bytes). */ MBEDTLS_SSL_CHK_BUF_PTR( p, end, 2 ); MBEDTLS_PUT_UINT16_BE( cipher_suite, p, 0 ); p += 2; } /* Write the cipher_suites length in number of bytes */ cipher_suites_len = p - cipher_suites_ptr; MBEDTLS_PUT_UINT16_BE( cipher_suites_len, buf, 0 ); MBEDTLS_SSL_DEBUG_MSG( 3, ( "client hello, got %" MBEDTLS_PRINTF_SIZET " cipher suites", cipher_suites_len/2 ) ); /* Output the total length of cipher_suites field. */ *olen = p - buf; return( 0 ); } /* * Structure of ClientHello message: * * 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_write_client_hello_body( mbedtls_ssl_context *ssl, unsigned char *buf, unsigned char *end, size_t *olen ) { int ret; unsigned char *extensions_len_ptr; /* Pointer to extensions length */ size_t output_len; /* Length of buffer used by function */ size_t extensions_len; /* Length of the list of extensions*/ /* Buffer management */ unsigned char *p = buf; *olen = 0; /* No validation needed here. It has been done by ssl_conf_check() */ ssl->major_ver = ssl->conf->min_major_ver; ssl->minor_ver = ssl->conf->min_minor_ver; /* * Write legacy_version * ProtocolVersion legacy_version = 0x0303; // TLS v1.2 * * For TLS 1.3 we use the legacy version number {0x03, 0x03} * instead of the true version number. */ MBEDTLS_SSL_CHK_BUF_PTR( p, end, 2 ); MBEDTLS_PUT_UINT16_BE( 0x0303, p, 0 ); p += 2; /* Write the random bytes ( random ).*/ MBEDTLS_SSL_CHK_BUF_PTR( p, end, MBEDTLS_CLIENT_HELLO_RANDOM_LEN ); memcpy( p, ssl->handshake->randbytes, MBEDTLS_CLIENT_HELLO_RANDOM_LEN ); MBEDTLS_SSL_DEBUG_BUF( 3, "client hello, random bytes", p, MBEDTLS_CLIENT_HELLO_RANDOM_LEN ); p += MBEDTLS_CLIENT_HELLO_RANDOM_LEN; /* * Write legacy_session_id * * Versions of TLS before TLS 1.3 supported a "session resumption" feature * which has been merged with pre-shared keys in this version. A client * which has a cached session ID set by a pre-TLS 1.3 server SHOULD set * this field to that value. In compatibility mode, this field MUST be * non-empty, so a client not offering a pre-TLS 1.3 session MUST generate * a new 32-byte value. This value need not be random but SHOULD be * unpredictable to avoid implementations fixating on a specific value * ( also known as ossification ). Otherwise, it MUST be set as a zero-length * vector ( i.e., a zero-valued single byte length field ). */ MBEDTLS_SSL_CHK_BUF_PTR( p, end, 1 ); *p++ = 0; /* session id length set to zero */ /* Write cipher_suites */ ret = ssl_tls13_write_client_hello_cipher_suites( ssl, p, end, &output_len ); if( ret != 0 ) return( ret ); p += output_len; /* Write legacy_compression_methods * * For every TLS 1.3 ClientHello, this vector MUST contain exactly * one byte set to zero, which corresponds to the 'null' compression * method in prior versions of TLS. */ MBEDTLS_SSL_CHK_BUF_PTR( p, end, 2 ); *p++ = 1; *p++ = MBEDTLS_SSL_COMPRESS_NULL; /* Write extensions */ /* Keeping track of the included extensions */ ssl->handshake->extensions_present = MBEDTLS_SSL_EXT_NONE; /* First write extensions, then the total length */ MBEDTLS_SSL_CHK_BUF_PTR( p, end, 2 ); extensions_len_ptr = p; p += 2; /* Write supported_versions extension * * Supported Versions Extension is mandatory with TLS 1.3. */ ret = ssl_tls13_write_supported_versions_ext( ssl, p, end, &output_len ); if( ret != 0 ) return( ret ); p += output_len; #if defined(MBEDTLS_KEY_EXCHANGE_WITH_CERT_ENABLED) /* Write supported_groups extension * * It is REQUIRED for ECDHE cipher_suites. */ ret = ssl_tls13_write_supported_groups_ext( ssl, p, end, &output_len ); if( ret != 0 ) return( ret ); p += output_len; /* Write key_share extension * * We need to send the key shares under three conditions: * 1) A certificate-based ciphersuite is being offered. In this case * supported_groups and supported_signature extensions have been * successfully added. * 2) A PSK-based ciphersuite with ECDHE is offered. In this case the * psk_key_exchange_modes has been added as the last extension. * 3) Or, in case all ciphers are supported ( which includes #1 and #2 * from above ) */ ret = ssl_tls13_write_key_share_ext( ssl, p, end, &output_len ); if( ret != 0 ) return( ret ); p += output_len; /* Write signature_algorithms extension * * It is REQUIRED for certificate authenticated cipher_suites. */ ret = mbedtls_ssl_tls13_write_sig_alg_ext( ssl, p, end, &output_len ); if( ret != 0 ) return( ret ); p += output_len; #endif /* MBEDTLS_KEY_EXCHANGE_WITH_CERT_ENABLED */ /* Add more extensions here */ /* Write the length of the list of extensions. */ extensions_len = p - extensions_len_ptr - 2; MBEDTLS_PUT_UINT16_BE( extensions_len, extensions_len_ptr, 0 ); MBEDTLS_SSL_DEBUG_MSG( 3, ( "client hello, total extension length: %" MBEDTLS_PRINTF_SIZET , extensions_len ) ); MBEDTLS_SSL_DEBUG_BUF( 3, "client hello extensions", extensions_len_ptr, extensions_len ); *olen = p - buf; return( 0 ); } static int ssl_tls13_finalize_client_hello( mbedtls_ssl_context *ssl ) { mbedtls_ssl_handshake_set_state( ssl, MBEDTLS_SSL_SERVER_HELLO ); return( 0 ); } static int ssl_tls13_prepare_client_hello( mbedtls_ssl_context *ssl ) { int ret; if( ssl->conf->f_rng == NULL ) { MBEDTLS_SSL_DEBUG_MSG( 1, ( "no RNG provided" ) ); return( MBEDTLS_ERR_SSL_NO_RNG ); } if( ( ret = ssl->conf->f_rng( ssl->conf->p_rng, ssl->handshake->randbytes, MBEDTLS_CLIENT_HELLO_RANDOM_LEN ) ) != 0 ) { MBEDTLS_SSL_DEBUG_RET( 1, "f_rng", ret ); return( ret ); } return( 0 ); } /* * Write ClientHello handshake message. * Handler for MBEDTLS_SSL_CLIENT_HELLO */ static int ssl_tls13_write_client_hello( mbedtls_ssl_context *ssl ) { int ret = 0; unsigned char *buf; size_t buf_len, msg_len; MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> write client hello" ) ); MBEDTLS_SSL_PROC_CHK( ssl_tls13_prepare_client_hello( ssl ) ); MBEDTLS_SSL_PROC_CHK( mbedtls_ssl_tls13_start_handshake_msg( ssl, MBEDTLS_SSL_HS_CLIENT_HELLO, &buf, &buf_len ) ); MBEDTLS_SSL_PROC_CHK( ssl_tls13_write_client_hello_body( ssl, buf, buf + buf_len, &msg_len ) ); mbedtls_ssl_tls13_add_hs_hdr_to_checksum( ssl, MBEDTLS_SSL_HS_CLIENT_HELLO, msg_len ); ssl->handshake->update_checksum( ssl, buf, msg_len ); MBEDTLS_SSL_PROC_CHK( ssl_tls13_finalize_client_hello( ssl ) ); MBEDTLS_SSL_PROC_CHK( mbedtls_ssl_tls13_finish_handshake_msg( ssl, buf_len, msg_len ) ); cleanup: MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= write client hello" ) ); return ret; } /* * Functions for parsing and processing Server Hello */ /* Returns a negative value on failure, and otherwise * - SSL_SERVER_HELLO_COORDINATE_HELLO or * - SSL_SERVER_HELLO_COORDINATE_HRR * to indicate which message is expected and to be parsed next. */ #define SSL_SERVER_HELLO_COORDINATE_HELLO 0 #define SSL_SERVER_HELLO_COORDINATE_HRR 1 static int ssl_server_hello_is_hrr( mbedtls_ssl_context *ssl, const unsigned char *buf, const unsigned char *end ) { static const unsigned char magic_hrr_string[MBEDTLS_SERVER_HELLO_RANDOM_LEN] = { 0xCF, 0x21, 0xAD, 0x74, 0xE5, 0x9A, 0x61, 0x11, 0xBE, 0x1D, 0x8C, 0x02, 0x1E, 0x65, 0xB8, 0x91, 0xC2, 0xA2, 0x11, 0x16, 0x7A, 0xBB, 0x8C, 0x5E, 0x07, 0x9E, 0x09, 0xE2, 0xC8, 0xA8, 0x33 ,0x9C }; /* Check whether this message is a HelloRetryRequest ( HRR ) message. * * Server Hello and HRR are only distinguished by Random set to the * special value of the SHA-256 of "HelloRetryRequest". * * struct { * ProtocolVersion legacy_version = 0x0303; * Random random; * opaque legacy_session_id_echo<0..32>; * CipherSuite cipher_suite; * uint8 legacy_compression_method = 0; * Extension extensions<6..2^16-1>; * } ServerHello; * */ MBEDTLS_SSL_CHK_BUF_READ_PTR( buf, end, 2 + sizeof( magic_hrr_string ) ); if( memcmp( buf + 2, magic_hrr_string, sizeof( magic_hrr_string ) ) == 0 ) { return( SSL_SERVER_HELLO_COORDINATE_HRR ); } return( SSL_SERVER_HELLO_COORDINATE_HELLO ); } /* Fetch and preprocess * Returns a negative value on failure, and otherwise * - SSL_SERVER_HELLO_COORDINATE_HELLO or * - SSL_SERVER_HELLO_COORDINATE_HRR */ static int ssl_tls13_server_hello_coordinate( mbedtls_ssl_context *ssl, unsigned char **buf, size_t *buf_len ) { int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; MBEDTLS_SSL_PROC_CHK( mbedtls_ssl_read_record( ssl, 0 ) ); if( ( ssl->in_msgtype != MBEDTLS_SSL_MSG_HANDSHAKE ) || ( ssl->in_msg[0] != MBEDTLS_SSL_HS_SERVER_HELLO ) ) { MBEDTLS_SSL_DEBUG_MSG( 1, ( "unexpected message" ) ); MBEDTLS_SSL_PEND_FATAL_ALERT( MBEDTLS_SSL_ALERT_MSG_UNEXPECTED_MESSAGE, MBEDTLS_ERR_SSL_UNEXPECTED_MESSAGE ); return( MBEDTLS_ERR_SSL_UNEXPECTED_MESSAGE ); } *buf = ssl->in_msg + 4; *buf_len = ssl->in_hslen - 4; ret = ssl_server_hello_is_hrr( ssl, *buf, *buf + *buf_len ); switch( ret ) { case SSL_SERVER_HELLO_COORDINATE_HELLO: MBEDTLS_SSL_DEBUG_MSG( 2, ( "received ServerHello message" ) ); break; case SSL_SERVER_HELLO_COORDINATE_HRR: MBEDTLS_SSL_DEBUG_MSG( 2, ( "received HelloRetryRequest message" ) ); break; } cleanup: return( ret ); } static int ssl_tls13_check_server_hello_session_id_echo( mbedtls_ssl_context *ssl, const unsigned char **buf, const unsigned char *end ) { const unsigned char *p = *buf; size_t legacy_session_id_echo_len; MBEDTLS_SSL_CHK_BUF_READ_PTR( p, end, 1 ); legacy_session_id_echo_len = *p++ ; MBEDTLS_SSL_CHK_BUF_READ_PTR( p, end, legacy_session_id_echo_len ); /* legacy_session_id_echo */ if( ssl->session_negotiate->id_len != legacy_session_id_echo_len || memcmp( ssl->session_negotiate->id, p , legacy_session_id_echo_len ) != 0 ) { MBEDTLS_SSL_DEBUG_BUF( 3, "Expected Session ID", ssl->session_negotiate->id, ssl->session_negotiate->id_len ); MBEDTLS_SSL_DEBUG_BUF( 3, "Received Session ID", p, legacy_session_id_echo_len ); MBEDTLS_SSL_PEND_FATAL_ALERT( MBEDTLS_SSL_ALERT_MSG_ILLEGAL_PARAMETER, MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER); return( MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER ); } p += legacy_session_id_echo_len; *buf = p; MBEDTLS_SSL_DEBUG_BUF( 3, "Session ID", ssl->session_negotiate->id, ssl->session_negotiate->id_len ); return( 0 ); } static int ssl_tls13_cipher_suite_is_offered( mbedtls_ssl_context *ssl, int cipher_suite ) { const int *ciphersuite_list = ssl->conf->ciphersuite_list; /* Check whether we have offered this ciphersuite */ for ( size_t i = 0; ciphersuite_list[i] != 0; i++ ) { if( ciphersuite_list[i] == cipher_suite ) { return( 1 ); } } return( 0 ); } /* Parse ServerHello message and configure context * * struct { * ProtocolVersion legacy_version = 0x0303; // TLS 1.2 * Random random; * opaque legacy_session_id_echo<0..32>; * CipherSuite cipher_suite; * uint8 legacy_compression_method = 0; * Extension extensions<6..2^16-1>; * } ServerHello; */ static int ssl_tls13_parse_server_hello( mbedtls_ssl_context *ssl, const unsigned char *buf, const unsigned char *end ) { int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; const unsigned char *p = buf; size_t extensions_len; const unsigned char *extensions_end; uint16_t cipher_suite; const mbedtls_ssl_ciphersuite_t *ciphersuite_info; /* * Check there is space for minimal fields * * - legacy_version ( 2 bytes) * - random (MBEDTLS_SERVER_HELLO_RANDOM_LEN bytes) * - legacy_session_id_echo ( 1 byte ), minimum size * - cipher_suite ( 2 bytes) * - legacy_compression_method ( 1 byte ) */ MBEDTLS_SSL_CHK_BUF_READ_PTR( p, end, MBEDTLS_SERVER_HELLO_RANDOM_LEN + 6 ); MBEDTLS_SSL_DEBUG_BUF( 4, "server hello", p, end - p ); MBEDTLS_SSL_DEBUG_BUF( 3, "server hello, version", p, 2 ); /* ... * 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 ); return( MBEDTLS_ERR_SSL_BAD_PROTOCOL_VERSION ); } p += 2; /* ... * Random random; * ... * with Random defined as: * opaque Random[MBEDTLS_SERVER_HELLO_RANDOM_LEN]; */ memcpy( &ssl->handshake->randbytes[MBEDTLS_CLIENT_HELLO_RANDOM_LEN], p, MBEDTLS_SERVER_HELLO_RANDOM_LEN ); MBEDTLS_SSL_DEBUG_BUF( 3, "server hello, random bytes", p, MBEDTLS_SERVER_HELLO_RANDOM_LEN ); p += MBEDTLS_SERVER_HELLO_RANDOM_LEN; /* ... * opaque legacy_session_id_echo<0..32>; * ... */ if( ssl_tls13_check_server_hello_session_id_echo( ssl, &p, end ) != 0 ) { MBEDTLS_SSL_PEND_FATAL_ALERT( MBEDTLS_SSL_ALERT_MSG_ILLEGAL_PARAMETER, MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER ); return( MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER ); } /* ... * CipherSuite cipher_suite; * ... * with CipherSuite defined as: * uint8 CipherSuite[2]; */ MBEDTLS_SSL_CHK_BUF_READ_PTR( p, end, 2 ); cipher_suite = MBEDTLS_GET_UINT16_BE( p, 0 ); p += 2; /* * Check whether this ciphersuite is supported and offered. * Via the force_ciphersuite version we may have instructed the client * to use a different ciphersuite. */ ciphersuite_info = mbedtls_ssl_ciphersuite_from_id( cipher_suite ); if( ciphersuite_info == NULL || ssl_tls13_cipher_suite_is_offered( ssl, cipher_suite ) == 0 ) { MBEDTLS_SSL_DEBUG_MSG( 1, ( "ciphersuite(%04x) not found or not offered", cipher_suite ) ); MBEDTLS_SSL_PEND_FATAL_ALERT( MBEDTLS_SSL_ALERT_MSG_ILLEGAL_PARAMETER, MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER ); return( MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER ); } /* Configure ciphersuites */ mbedtls_ssl_optimize_checksum( ssl, ciphersuite_info ); ssl->handshake->ciphersuite_info = ciphersuite_info; ssl->session_negotiate->ciphersuite = cipher_suite; MBEDTLS_SSL_DEBUG_MSG( 3, ( "server hello, chosen ciphersuite: ( %04x ) - %s", cipher_suite, ciphersuite_info->name ) ); #if defined(MBEDTLS_HAVE_TIME) ssl->session_negotiate->start = time( NULL ); #endif /* MBEDTLS_HAVE_TIME */ /* ... * 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++; /* ... * Extension extensions<6..2^16-1>; * ... * struct { * ExtensionType extension_type; (2 bytes) * opaque extension_data<0..2^16-1>; * } Extension; */ MBEDTLS_SSL_CHK_BUF_READ_PTR( p, end, 2 ); extensions_len = MBEDTLS_GET_UINT16_BE( p, 0 ); p += 2; /* Check extensions do not go beyond the buffer of data. */ MBEDTLS_SSL_CHK_BUF_READ_PTR( p, end, extensions_len ); extensions_end = p + extensions_len; MBEDTLS_SSL_DEBUG_BUF( 3, "server hello extensions", p, extensions_len ); while( p < extensions_end ) { unsigned int extension_type; size_t extension_data_len; MBEDTLS_SSL_CHK_BUF_READ_PTR( p, extensions_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 ); switch( extension_type ) { case MBEDTLS_TLS_EXT_SUPPORTED_VERSIONS: MBEDTLS_SSL_DEBUG_MSG( 3, ( "found supported_versions extension" ) ); ret = ssl_tls13_parse_supported_versions_ext( ssl, p, p + extension_data_len ); if( ret != 0 ) return( ret ); break; case MBEDTLS_TLS_EXT_PRE_SHARED_KEY: MBEDTLS_SSL_DEBUG_MSG( 3, ( "found pre_shared_key extension." ) ); MBEDTLS_SSL_DEBUG_MSG( 3, ( "pre_shared_key:Not supported yet" ) ); MBEDTLS_SSL_PEND_FATAL_ALERT( MBEDTLS_SSL_ALERT_MSG_UNSUPPORTED_EXT, MBEDTLS_ERR_SSL_UNSUPPORTED_EXTENSION ); return( MBEDTLS_ERR_SSL_UNSUPPORTED_EXTENSION ); #if defined(MBEDTLS_KEY_EXCHANGE_WITH_CERT_ENABLED) case MBEDTLS_TLS_EXT_KEY_SHARE: MBEDTLS_SSL_DEBUG_MSG( 3, ( "found key_shares extension" ) ); if( ( ret = ssl_tls13_parse_key_share_ext( ssl, p, p + extension_data_len ) ) != 0 ) { MBEDTLS_SSL_DEBUG_RET( 1, "ssl_tls13_parse_key_share_ext", ret ); return( ret ); } break; #endif /* MBEDTLS_KEY_EXCHANGE_WITH_CERT_ENABLED */ default: MBEDTLS_SSL_DEBUG_MSG( 3, ( "unknown extension found: %u ( ignoring )", extension_type ) ); MBEDTLS_SSL_PEND_FATAL_ALERT( MBEDTLS_SSL_ALERT_MSG_UNSUPPORTED_EXT, MBEDTLS_ERR_SSL_UNSUPPORTED_EXTENSION ); return( MBEDTLS_ERR_SSL_UNSUPPORTED_EXTENSION ); } p += extension_data_len; } return( 0 ); } static int ssl_tls13_finalize_server_hello( mbedtls_ssl_context *ssl ) { int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; mbedtls_ssl_key_set traffic_keys; mbedtls_ssl_transform *transform_handshake = NULL; mbedtls_ssl_handshake_params *handshake = ssl->handshake; /* Determine the key exchange mode: * 1) If both the pre_shared_key and key_share extensions were received * then the key exchange mode is PSK with EPHEMERAL. * 2) If only the pre_shared_key extension was received then the key * exchange mode is PSK-only. * 3) If only the key_share extension was received then the key * exchange mode is EPHEMERAL-only. */ switch( handshake->extensions_present & ( MBEDTLS_SSL_EXT_PRE_SHARED_KEY | MBEDTLS_SSL_EXT_KEY_SHARE ) ) { /* Only the pre_shared_key extension was received */ case MBEDTLS_SSL_EXT_PRE_SHARED_KEY: handshake->tls1_3_kex_modes = MBEDTLS_SSL_TLS13_KEY_EXCHANGE_MODE_PSK; break; /* Only the key_share extension was received */ case MBEDTLS_SSL_EXT_KEY_SHARE: handshake->tls1_3_kex_modes = MBEDTLS_SSL_TLS13_KEY_EXCHANGE_MODE_EPHEMERAL; break; /* Both the pre_shared_key and key_share extensions were received */ case ( MBEDTLS_SSL_EXT_PRE_SHARED_KEY | MBEDTLS_SSL_EXT_KEY_SHARE ): handshake->tls1_3_kex_modes = MBEDTLS_SSL_TLS13_KEY_EXCHANGE_MODE_PSK_EPHEMERAL; break; /* Neither pre_shared_key nor key_share extension was received */ default: MBEDTLS_SSL_DEBUG_MSG( 1, ( "Unknown key exchange." ) ); ret = MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE; goto cleanup; } /* Start the TLS 1.3 key schedule: Set the PSK and derive early secret. * * TODO: We don't have to do this in case we offered 0-RTT and the * server accepted it. In this case, we could skip generating * the early secret. */ ret = mbedtls_ssl_tls1_3_key_schedule_stage_early( ssl ); if( ret != 0 ) { MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_tls1_3_key_schedule_stage_early_data", ret ); goto cleanup; } /* Compute handshake secret */ ret = mbedtls_ssl_tls13_key_schedule_stage_handshake( ssl ); if( ret != 0 ) { MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_tls1_3_derive_master_secret", ret ); goto cleanup; } /* Next evolution in key schedule: Establish handshake secret and * key material. */ ret = mbedtls_ssl_tls13_generate_handshake_keys( ssl, &traffic_keys ); if( ret != 0 ) { MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_tls13_generate_handshake_keys", ret ); goto cleanup; } transform_handshake = mbedtls_calloc( 1, sizeof( mbedtls_ssl_transform ) ); if( transform_handshake == NULL ) { ret = MBEDTLS_ERR_SSL_ALLOC_FAILED; goto cleanup; } ret = mbedtls_ssl_tls13_populate_transform( transform_handshake, ssl->conf->endpoint, ssl->session_negotiate->ciphersuite, &traffic_keys, ssl ); if( ret != 0 ) { MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_tls13_populate_transform", ret ); goto cleanup; } handshake->transform_handshake = transform_handshake; mbedtls_ssl_set_inbound_transform( ssl, transform_handshake ); MBEDTLS_SSL_DEBUG_MSG( 1, ( "Switch to handshake keys for inbound traffic" ) ); ssl->session_in = ssl->session_negotiate; /* * State machine update */ mbedtls_ssl_handshake_set_state( ssl, MBEDTLS_SSL_ENCRYPTED_EXTENSIONS ); cleanup: mbedtls_platform_zeroize( &traffic_keys, sizeof( traffic_keys ) ); if( ret != 0 ) { mbedtls_free( transform_handshake ); MBEDTLS_SSL_PEND_FATAL_ALERT( MBEDTLS_SSL_ALERT_MSG_HANDSHAKE_FAILURE, MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE ); } return( ret ); } /* * Wait and parse ServerHello handshake message. * Handler for MBEDTLS_SSL_SERVER_HELLO */ static int ssl_tls1_3_process_server_hello( mbedtls_ssl_context *ssl ) { int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; unsigned char *buf; size_t buf_len; MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> %s", __func__ ) ); /* Coordination step * - Fetch record * - Make sure it's either a ServerHello or a HRR. * - Switch processing routine in case of HRR */ ssl->major_ver = MBEDTLS_SSL_MAJOR_VERSION_3; ssl->handshake->extensions_present = MBEDTLS_SSL_EXT_NONE; ret = ssl_tls13_server_hello_coordinate( ssl, &buf, &buf_len ); /* Parsing step * We know what message to expect by now and call * the respective parsing function. */ if( ret == SSL_SERVER_HELLO_COORDINATE_HELLO ) { MBEDTLS_SSL_PROC_CHK( ssl_tls13_parse_server_hello( ssl, buf, buf + buf_len ) ); mbedtls_ssl_tls1_3_add_hs_msg_to_checksum( ssl, MBEDTLS_SSL_HS_SERVER_HELLO, buf, buf_len ); MBEDTLS_SSL_PROC_CHK( ssl_tls13_finalize_server_hello( ssl ) ); } else if( ret == SSL_SERVER_HELLO_COORDINATE_HRR ) { MBEDTLS_SSL_DEBUG_MSG( 1, ( "HRR not supported" ) ); MBEDTLS_SSL_PEND_FATAL_ALERT( MBEDTLS_SSL_ALERT_MSG_HANDSHAKE_FAILURE , MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE ); ret = MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE; } cleanup: MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= %s", __func__ ) ); return( ret ); } /* * * EncryptedExtensions message * * The EncryptedExtensions message contains any extensions which * should be protected, i.e., any which are not needed to establish * the cryptographic context. */ /* * Overview */ /* Main entry point; orchestrates the other functions */ static int ssl_tls13_process_encrypted_extensions( mbedtls_ssl_context *ssl ); static int ssl_tls13_parse_encrypted_extensions( mbedtls_ssl_context *ssl, const unsigned char *buf, const unsigned char *end ); static int ssl_tls13_postprocess_encrypted_extensions( mbedtls_ssl_context *ssl ); /* * Handler for MBEDTLS_SSL_ENCRYPTED_EXTENSIONS */ static int ssl_tls13_process_encrypted_extensions( mbedtls_ssl_context *ssl ) { int ret; unsigned char *buf; size_t buf_len; MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> parse encrypted extensions" ) ); MBEDTLS_SSL_PROC_CHK( mbedtls_ssl_tls1_3_fetch_handshake_msg( ssl, MBEDTLS_SSL_HS_ENCRYPTED_EXTENSIONS, &buf, &buf_len ) ); /* Process the message contents */ MBEDTLS_SSL_PROC_CHK( ssl_tls13_parse_encrypted_extensions( ssl, buf, buf + buf_len ) ); mbedtls_ssl_tls1_3_add_hs_msg_to_checksum( ssl, MBEDTLS_SSL_HS_ENCRYPTED_EXTENSIONS, buf, buf_len ); MBEDTLS_SSL_PROC_CHK( ssl_tls13_postprocess_encrypted_extensions( ssl ) ); cleanup: MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= parse encrypted extensions" ) ); return( ret ); } /* Parse EncryptedExtensions message * struct { * Extension extensions<0..2^16-1>; * } EncryptedExtensions; */ static int ssl_tls13_parse_encrypted_extensions( mbedtls_ssl_context *ssl, const unsigned char *buf, const unsigned char *end ) { int ret = 0; size_t extensions_len; const unsigned char *p = buf; const unsigned char *extensions_end; MBEDTLS_SSL_CHK_BUF_READ_PTR( p, end, 2 ); extensions_len = MBEDTLS_GET_UINT16_BE( p, 0 ); p += 2; MBEDTLS_SSL_DEBUG_BUF( 3, "encrypted extensions", p, extensions_len ); extensions_end = p + extensions_len; MBEDTLS_SSL_CHK_BUF_READ_PTR( p, end, extensions_len ); while( p < extensions_end ) { unsigned int extension_type; size_t extension_data_len; /* * struct { * ExtensionType extension_type; (2 bytes) * opaque extension_data<0..2^16-1>; * } Extension; */ MBEDTLS_SSL_CHK_BUF_READ_PTR( p, extensions_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 ); /* The client MUST check EncryptedExtensions for the * presence of any forbidden extensions and if any are found MUST abort * the handshake with an "unsupported_extension" alert. */ switch( extension_type ) { case MBEDTLS_TLS_EXT_SUPPORTED_GROUPS: MBEDTLS_SSL_DEBUG_MSG( 3, ( "found extensions supported groups" ) ); break; default: MBEDTLS_SSL_DEBUG_MSG( 3, ( "unsupported extension found: %u ", extension_type) ); MBEDTLS_SSL_PEND_FATAL_ALERT( MBEDTLS_SSL_ALERT_MSG_UNSUPPORTED_EXT, \ MBEDTLS_ERR_SSL_UNSUPPORTED_EXTENSION ); return ( MBEDTLS_ERR_SSL_UNSUPPORTED_EXTENSION ); } p += extension_data_len; } /* Check that we consumed all the message. */ if( p != end ) { MBEDTLS_SSL_DEBUG_MSG( 1, ( "EncryptedExtension lengths misaligned" ) ); MBEDTLS_SSL_PEND_FATAL_ALERT( MBEDTLS_SSL_ALERT_MSG_DECODE_ERROR, \ MBEDTLS_ERR_SSL_DECODE_ERROR ); return( MBEDTLS_ERR_SSL_DECODE_ERROR ); } return( ret ); } static int ssl_tls13_postprocess_encrypted_extensions( mbedtls_ssl_context *ssl ) { mbedtls_ssl_handshake_set_state( ssl, MBEDTLS_SSL_CERTIFICATE_REQUEST ); return( 0 ); } /* * Handler for MBEDTLS_SSL_CERTIFICATE_REQUEST */ static int ssl_tls1_3_process_certificate_request( mbedtls_ssl_context *ssl ) { MBEDTLS_SSL_DEBUG_MSG( 1, ( "%s hasn't been implemented", __func__ ) ); mbedtls_ssl_handshake_set_state( ssl, MBEDTLS_SSL_SERVER_CERTIFICATE ); return( 0 ); } /* * Handler for MBEDTLS_SSL_SERVER_CERTIFICATE */ static int ssl_tls1_3_process_server_certificate( mbedtls_ssl_context *ssl ) { MBEDTLS_SSL_DEBUG_MSG( 1, ( "%s hasn't been implemented", __func__ ) ); mbedtls_ssl_handshake_set_state( ssl, MBEDTLS_SSL_CERTIFICATE_VERIFY ); return( 0 ); } /* * Handler for MBEDTLS_SSL_CERTIFICATE_VERIFY */ static int ssl_tls1_3_process_certificate_verify( mbedtls_ssl_context *ssl ) { MBEDTLS_SSL_DEBUG_MSG( 1, ( "%s hasn't been implemented", __func__ ) ); mbedtls_ssl_handshake_set_state( ssl, MBEDTLS_SSL_SERVER_FINISHED ); return( 0 ); } /* * Handler for MBEDTLS_SSL_SERVER_FINISHED */ static int ssl_tls1_3_process_server_finished( mbedtls_ssl_context *ssl ) { MBEDTLS_SSL_DEBUG_MSG( 1, ( "%s hasn't been implemented", __func__ ) ); mbedtls_ssl_handshake_set_state( ssl, MBEDTLS_SSL_CLIENT_CERTIFICATE ); return( 0 ); } /* * Handler for MBEDTLS_SSL_CLIENT_CERTIFICATE */ static int ssl_tls1_3_write_client_certificate( mbedtls_ssl_context *ssl ) { MBEDTLS_SSL_DEBUG_MSG( 1, ( "%s hasn't been implemented", __func__ ) ); mbedtls_ssl_handshake_set_state( ssl, MBEDTLS_SSL_CLIENT_CERTIFICATE_VERIFY ); return( 0 ); } /* * Handler for MBEDTLS_SSL_CLIENT_CERTIFICATE_VERIFY */ static int ssl_tls1_3_write_client_certificate_verify( mbedtls_ssl_context *ssl ) { MBEDTLS_SSL_DEBUG_MSG( 1, ( "%s hasn't been implemented", __func__ ) ); mbedtls_ssl_handshake_set_state( ssl, MBEDTLS_SSL_CLIENT_FINISHED ); return( 0 ); } /* * Handler for MBEDTLS_SSL_CLIENT_FINISHED */ static int ssl_tls1_3_write_client_finished( mbedtls_ssl_context *ssl ) { MBEDTLS_SSL_DEBUG_MSG( 1, ( "%s hasn't been implemented", __func__ ) ); mbedtls_ssl_handshake_set_state( ssl, MBEDTLS_SSL_FLUSH_BUFFERS ); return( 0 ); } /* * Handler for MBEDTLS_SSL_FLUSH_BUFFERS */ static int ssl_tls1_3_flush_buffers( mbedtls_ssl_context *ssl ) { MBEDTLS_SSL_DEBUG_MSG( 1, ( "%s hasn't been implemented", __func__ ) ); mbedtls_ssl_handshake_set_state( ssl, MBEDTLS_SSL_HANDSHAKE_WRAPUP ); return( 0 ); } /* * Handler for MBEDTLS_SSL_HANDSHAKE_WRAPUP */ static int ssl_tls1_3_handshake_wrapup( mbedtls_ssl_context *ssl ) { ((void) ssl); MBEDTLS_SSL_DEBUG_MSG( 1, ( "%s hasn't been implemented", __func__ ) ); return( MBEDTLS_ERR_SSL_FEATURE_UNAVAILABLE ); } int mbedtls_ssl_tls13_handshake_client_step( mbedtls_ssl_context *ssl ) { int ret = 0; MBEDTLS_SSL_DEBUG_MSG( 2, ( "tls1_3 client state: %d", ssl->state ) ); switch( ssl->state ) { /* * ssl->state is initialized as HELLO_REQUEST. It is the same * as CLIENT_HELLO state. */ case MBEDTLS_SSL_HELLO_REQUEST: case MBEDTLS_SSL_CLIENT_HELLO: ret = ssl_tls13_write_client_hello( ssl ); break; case MBEDTLS_SSL_SERVER_HELLO: ret = ssl_tls1_3_process_server_hello( ssl ); break; case MBEDTLS_SSL_ENCRYPTED_EXTENSIONS: ret = ssl_tls13_process_encrypted_extensions( ssl ); break; case MBEDTLS_SSL_CERTIFICATE_REQUEST: ret = ssl_tls1_3_process_certificate_request( ssl ); break; case MBEDTLS_SSL_SERVER_CERTIFICATE: ret = ssl_tls1_3_process_server_certificate( ssl ); break; case MBEDTLS_SSL_CERTIFICATE_VERIFY: ret = ssl_tls1_3_process_certificate_verify( ssl ); break; case MBEDTLS_SSL_SERVER_FINISHED: ret = ssl_tls1_3_process_server_finished( ssl ); break; case MBEDTLS_SSL_CLIENT_CERTIFICATE: ret = ssl_tls1_3_write_client_certificate( ssl ); break; case MBEDTLS_SSL_CLIENT_CERTIFICATE_VERIFY: ret = ssl_tls1_3_write_client_certificate_verify( ssl ); break; case MBEDTLS_SSL_CLIENT_FINISHED: ret = ssl_tls1_3_write_client_finished( ssl ); break; case MBEDTLS_SSL_FLUSH_BUFFERS: ret = ssl_tls1_3_flush_buffers( ssl ); break; case MBEDTLS_SSL_HANDSHAKE_WRAPUP: ret = ssl_tls1_3_handshake_wrapup( ssl ); break; default: MBEDTLS_SSL_DEBUG_MSG( 1, ( "invalid state %d", ssl->state ) ); return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA ); } return( ret ); } #endif /* MBEDTLS_SSL_CLI_C */ #endif /* MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL */