/* * TLS 1.3 functionality shared between client and server * * 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_TLS_C) #if defined(MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL) #include #include "mbedtls/error.h" #include "mbedtls/debug.h" #include "mbedtls/oid.h" #include "mbedtls/platform.h" #include "mbedtls/constant_time.h" #include #include "ssl_misc.h" #include "ssl_tls13_keys.h" int mbedtls_ssl_tls13_fetch_handshake_msg( mbedtls_ssl_context *ssl, unsigned hs_type, unsigned char **buf, size_t *buf_len ) { int ret; if( ( ret = mbedtls_ssl_read_record( ssl, 0 ) ) != 0 ) { MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_read_record", ret ); goto cleanup; } if( ssl->in_msgtype != MBEDTLS_SSL_MSG_HANDSHAKE || ssl->in_msg[0] != hs_type ) { MBEDTLS_SSL_DEBUG_MSG( 1, ( "Receive unexpected handshake message." ) ); MBEDTLS_SSL_PEND_FATAL_ALERT( MBEDTLS_SSL_ALERT_MSG_UNEXPECTED_MESSAGE, MBEDTLS_ERR_SSL_UNEXPECTED_MESSAGE ); ret = MBEDTLS_ERR_SSL_UNEXPECTED_MESSAGE; goto cleanup; } /* * Jump handshake header (4 bytes, see Section 4 of RFC 8446). * ... * HandshakeType msg_type; * uint24 length; * ... */ *buf = ssl->in_msg + 4; *buf_len = ssl->in_hslen - 4; cleanup: return( ret ); } int mbedtls_ssl_tls13_start_handshake_msg( mbedtls_ssl_context *ssl, unsigned hs_type, unsigned char **buf, size_t *buf_len ) { /* * Reserve 4 bytes for hanshake header. ( Section 4,RFC 8446 ) * ... * HandshakeType msg_type; * uint24 length; * ... */ *buf = ssl->out_msg + 4; *buf_len = MBEDTLS_SSL_OUT_CONTENT_LEN - 4; ssl->out_msgtype = MBEDTLS_SSL_MSG_HANDSHAKE; ssl->out_msg[0] = hs_type; return( 0 ); } int mbedtls_ssl_tls13_finish_handshake_msg( mbedtls_ssl_context *ssl, size_t buf_len, size_t msg_len ) { int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; size_t msg_with_header_len; ((void) buf_len); /* Add reserved 4 bytes for handshake header */ msg_with_header_len = msg_len + 4; ssl->out_msglen = msg_with_header_len; MBEDTLS_SSL_PROC_CHK( mbedtls_ssl_write_handshake_msg_ext( ssl, 0 ) ); cleanup: return( ret ); } void mbedtls_ssl_tls13_add_hs_msg_to_checksum( mbedtls_ssl_context *ssl, unsigned hs_type, unsigned char const *msg, size_t msg_len ) { mbedtls_ssl_tls13_add_hs_hdr_to_checksum( ssl, hs_type, msg_len ); ssl->handshake->update_checksum( ssl, msg, msg_len ); } void mbedtls_ssl_tls13_add_hs_hdr_to_checksum( mbedtls_ssl_context *ssl, unsigned hs_type, size_t total_hs_len ) { unsigned char hs_hdr[4]; /* Build HS header for checksum update. */ hs_hdr[0] = MBEDTLS_BYTE_0( hs_type ); hs_hdr[1] = MBEDTLS_BYTE_2( total_hs_len ); hs_hdr[2] = MBEDTLS_BYTE_1( total_hs_len ); hs_hdr[3] = MBEDTLS_BYTE_0( total_hs_len ); ssl->handshake->update_checksum( ssl, hs_hdr, sizeof( hs_hdr ) ); } #if defined(MBEDTLS_KEY_EXCHANGE_WITH_CERT_ENABLED) /* * mbedtls_ssl_tls13_write_sig_alg_ext( ) * * enum { * .... * ecdsa_secp256r1_sha256( 0x0403 ), * ecdsa_secp384r1_sha384( 0x0503 ), * ecdsa_secp521r1_sha512( 0x0603 ), * .... * } SignatureScheme; * * struct { * SignatureScheme supported_signature_algorithms<2..2^16-2>; * } SignatureSchemeList; * * Only if we handle at least one key exchange that needs signatures. */ int mbedtls_ssl_tls13_write_sig_alg_ext( mbedtls_ssl_context *ssl, unsigned char *buf, unsigned char *end, size_t *out_len ) { unsigned char *p = buf; unsigned char *supported_sig_alg; /* Start of supported_signature_algorithms */ size_t supported_sig_alg_len = 0; /* Length of supported_signature_algorithms */ *out_len = 0; /* Skip the extension on the client if all allowed key exchanges * are PSK-based. */ #if defined(MBEDTLS_SSL_CLI_C) if( ssl->conf->endpoint == MBEDTLS_SSL_IS_CLIENT && !mbedtls_ssl_conf_tls13_some_ephemeral_enabled( ssl ) ) { return( 0 ); } #endif /* MBEDTLS_SSL_CLI_C */ MBEDTLS_SSL_DEBUG_MSG( 3, ( "adding signature_algorithms extension" ) ); /* Check if we have space for header and length field: * - extension_type (2 bytes) * - extension_data_length (2 bytes) * - supported_signature_algorithms_length (2 bytes) */ MBEDTLS_SSL_CHK_BUF_PTR( p, end, 6 ); p += 6; /* * Write supported_signature_algorithms */ supported_sig_alg = p; for( const uint16_t *sig_alg = ssl->conf->tls13_sig_algs; *sig_alg != MBEDTLS_TLS1_3_SIG_NONE; sig_alg++ ) { MBEDTLS_SSL_CHK_BUF_PTR( p, end, 2 ); MBEDTLS_PUT_UINT16_BE( *sig_alg, p, 0 ); p += 2; MBEDTLS_SSL_DEBUG_MSG( 3, ( "signature scheme [%x]", *sig_alg ) ); } /* Length of supported_signature_algorithms */ supported_sig_alg_len = p - supported_sig_alg; if( supported_sig_alg_len == 0 ) { MBEDTLS_SSL_DEBUG_MSG( 1, ( "No signature algorithms defined." ) ); return( MBEDTLS_ERR_SSL_INTERNAL_ERROR ); } /* Write extension_type */ MBEDTLS_PUT_UINT16_BE( MBEDTLS_TLS_EXT_SIG_ALG, buf, 0 ); /* Write extension_data_length */ MBEDTLS_PUT_UINT16_BE( supported_sig_alg_len + 2, buf, 2 ); /* Write length of supported_signature_algorithms */ MBEDTLS_PUT_UINT16_BE( supported_sig_alg_len, buf, 4 ); /* Output the total length of signature algorithms extension. */ *out_len = p - buf; ssl->handshake->extensions_present |= MBEDTLS_SSL_EXT_SIG_ALG; return( 0 ); } /* * STATE HANDLING: Read CertificateVerify */ /* Macro to express the maximum length of the verify structure. * * The structure is computed per TLS 1.3 specification as: * - 64 bytes of octet 32, * - 33 bytes for the context string * (which is either "TLS 1.3, client CertificateVerify" * or "TLS 1.3, server CertificateVerify"), * - 1 byte for the octet 0x0, which serves as a separator, * - 32 or 48 bytes for the Transcript-Hash(Handshake Context, Certificate) * (depending on the size of the transcript_hash) * * This results in a total size of * - 130 bytes for a SHA256-based transcript hash, or * (64 + 33 + 1 + 32 bytes) * - 146 bytes for a SHA384-based transcript hash. * (64 + 33 + 1 + 48 bytes) * */ #define SSL_VERIFY_STRUCT_MAX_SIZE ( 64 + \ 33 + \ 1 + \ MBEDTLS_TLS1_3_MD_MAX_SIZE \ ) /* * The ssl_tls13_create_verify_structure() creates the verify structure. * As input, it requires the transcript hash. * * The caller has to ensure that the buffer has size at least * SSL_VERIFY_STRUCT_MAX_SIZE bytes. */ static void ssl_tls13_create_verify_structure( const unsigned char *transcript_hash, size_t transcript_hash_len, unsigned char *verify_buffer, size_t *verify_buffer_len, int from ) { size_t idx; /* RFC 8446, Section 4.4.3: * * The digital signature [in the CertificateVerify message] is then * computed over the concatenation of: * - A string that consists of octet 32 (0x20) repeated 64 times * - The context string * - A single 0 byte which serves as the separator * - The content to be signed */ memset( verify_buffer, 0x20, 64 ); idx = 64; if( from == MBEDTLS_SSL_IS_CLIENT ) { memcpy( verify_buffer + idx, MBEDTLS_SSL_TLS1_3_LBL_WITH_LEN( client_cv ) ); idx += MBEDTLS_SSL_TLS1_3_LBL_LEN( client_cv ); } else { /* from == MBEDTLS_SSL_IS_SERVER */ memcpy( verify_buffer + idx, MBEDTLS_SSL_TLS1_3_LBL_WITH_LEN( server_cv ) ); idx += MBEDTLS_SSL_TLS1_3_LBL_LEN( server_cv ); } verify_buffer[idx++] = 0x0; memcpy( verify_buffer + idx, transcript_hash, transcript_hash_len ); idx += transcript_hash_len; *verify_buffer_len = idx; } static int ssl_tls13_sig_alg_is_offered( const mbedtls_ssl_context *ssl, uint16_t sig_alg ) { const uint16_t *tls13_sig_alg = ssl->conf->tls13_sig_algs; for( ; *tls13_sig_alg != MBEDTLS_TLS1_3_SIG_NONE ; tls13_sig_alg++ ) { if( *tls13_sig_alg == sig_alg ) return( 1 ); } return( 0 ); } static int ssl_tls13_parse_certificate_verify( mbedtls_ssl_context *ssl, const unsigned char *buf, const unsigned char *end, const unsigned char *verify_buffer, size_t verify_buffer_len ) { int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; const unsigned char *p = buf; uint16_t algorithm; size_t signature_len; mbedtls_pk_type_t sig_alg; mbedtls_md_type_t md_alg; unsigned char verify_hash[MBEDTLS_MD_MAX_SIZE]; size_t verify_hash_len; void const *options = NULL; #if defined(MBEDTLS_X509_RSASSA_PSS_SUPPORT) mbedtls_pk_rsassa_pss_options rsassa_pss_options; #endif /* MBEDTLS_X509_RSASSA_PSS_SUPPORT */ /* * struct { * SignatureScheme algorithm; * opaque signature<0..2^16-1>; * } CertificateVerify; */ MBEDTLS_SSL_CHK_BUF_READ_PTR( p, end, 2 ); algorithm = MBEDTLS_GET_UINT16_BE( p, 0 ); p += 2; /* RFC 8446 section 4.4.3 * * If the CertificateVerify message is sent by a server, the signature algorithm * MUST be one offered in the client's "signature_algorithms" extension unless * no valid certificate chain can be produced without unsupported algorithms * * RFC 8446 section 4.4.2.2 * * If the client cannot construct an acceptable chain using the provided * certificates and decides to abort the handshake, then it MUST abort the handshake * with an appropriate certificate-related alert (by default, "unsupported_certificate"). * * Check if algorithm is an offered signature algorithm. */ if( ! ssl_tls13_sig_alg_is_offered( ssl, algorithm ) ) { /* algorithm not in offered signature algorithms list */ MBEDTLS_SSL_DEBUG_MSG( 1, ( "Received signature algorithm(%04x) is not " "offered.", ( unsigned int ) algorithm ) ); goto error; } /* We currently only support ECDSA-based signatures */ switch( algorithm ) { case MBEDTLS_TLS1_3_SIG_ECDSA_SECP256R1_SHA256: md_alg = MBEDTLS_MD_SHA256; sig_alg = MBEDTLS_PK_ECDSA; break; case MBEDTLS_TLS1_3_SIG_ECDSA_SECP384R1_SHA384: md_alg = MBEDTLS_MD_SHA384; sig_alg = MBEDTLS_PK_ECDSA; break; case MBEDTLS_TLS1_3_SIG_ECDSA_SECP521R1_SHA512: md_alg = MBEDTLS_MD_SHA512; sig_alg = MBEDTLS_PK_ECDSA; break; #if defined(MBEDTLS_X509_RSASSA_PSS_SUPPORT) case MBEDTLS_TLS1_3_SIG_RSA_PSS_RSAE_SHA256: MBEDTLS_SSL_DEBUG_MSG( 4, ( "Certificate Verify: using RSA PSS" ) ); md_alg = MBEDTLS_MD_SHA256; sig_alg = MBEDTLS_PK_RSASSA_PSS; break; #endif /* MBEDTLS_X509_RSASSA_PSS_SUPPORT */ default: MBEDTLS_SSL_DEBUG_MSG( 1, ( "Certificate Verify: Unknown signature algorithm." ) ); goto error; } MBEDTLS_SSL_DEBUG_MSG( 3, ( "Certificate Verify: Signature algorithm ( %04x )", ( unsigned int ) algorithm ) ); /* * Check the certificate's key type matches the signature alg */ if( !mbedtls_pk_can_do( &ssl->session_negotiate->peer_cert->pk, sig_alg ) ) { MBEDTLS_SSL_DEBUG_MSG( 1, ( "signature algorithm doesn't match cert key" ) ); goto error; } MBEDTLS_SSL_CHK_BUF_READ_PTR( p, end, 2 ); signature_len = MBEDTLS_GET_UINT16_BE( p, 0 ); p += 2; MBEDTLS_SSL_CHK_BUF_READ_PTR( p, end, signature_len ); /* Hash verify buffer with indicated hash function */ switch( md_alg ) { #if defined(MBEDTLS_SHA256_C) case MBEDTLS_MD_SHA256: verify_hash_len = 32; ret = mbedtls_sha256( verify_buffer, verify_buffer_len, verify_hash, 0 ); break; #endif /* MBEDTLS_SHA256_C */ #if defined(MBEDTLS_SHA384_C) case MBEDTLS_MD_SHA384: verify_hash_len = 48; ret = mbedtls_sha512( verify_buffer, verify_buffer_len, verify_hash, 1 ); break; #endif /* MBEDTLS_SHA384_C */ #if defined(MBEDTLS_SHA512_C) case MBEDTLS_MD_SHA512: verify_hash_len = 64; ret = mbedtls_sha512( verify_buffer, verify_buffer_len, verify_hash, 0 ); break; #endif /* MBEDTLS_SHA512_C */ default: ret = MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE; break; } if( ret != 0 ) { MBEDTLS_SSL_DEBUG_RET( 1, "hash computation error", ret ); goto error; } MBEDTLS_SSL_DEBUG_BUF( 3, "verify hash", verify_hash, verify_hash_len ); #if defined(MBEDTLS_X509_RSASSA_PSS_SUPPORT) if( sig_alg == MBEDTLS_PK_RSASSA_PSS ) { const mbedtls_md_info_t* md_info; rsassa_pss_options.mgf1_hash_id = md_alg; if( ( md_info = mbedtls_md_info_from_type( md_alg ) ) == NULL ) { return( MBEDTLS_ERR_SSL_INTERNAL_ERROR ); } rsassa_pss_options.expected_salt_len = mbedtls_md_get_size( md_info ); options = (const void*) &rsassa_pss_options; } #endif /* MBEDTLS_X509_RSASSA_PSS_SUPPORT */ if( ( ret = mbedtls_pk_verify_ext( sig_alg, options, &ssl->session_negotiate->peer_cert->pk, md_alg, verify_hash, verify_hash_len, p, signature_len ) ) == 0 ) { return( 0 ); } MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_pk_verify_ext", ret ); error: /* RFC 8446 section 4.4.3 * * If the verification fails, the receiver MUST terminate the handshake * with a "decrypt_error" alert. */ MBEDTLS_SSL_PEND_FATAL_ALERT( MBEDTLS_SSL_ALERT_MSG_DECRYPT_ERROR, MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE ); return( MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE ); } #endif /* MBEDTLS_KEY_EXCHANGE_WITH_CERT_ENABLED */ int mbedtls_ssl_tls13_process_certificate_verify( mbedtls_ssl_context *ssl ) { #if defined(MBEDTLS_KEY_EXCHANGE_WITH_CERT_ENABLED) int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; unsigned char verify_buffer[SSL_VERIFY_STRUCT_MAX_SIZE]; size_t verify_buffer_len; unsigned char transcript[MBEDTLS_TLS1_3_MD_MAX_SIZE]; size_t transcript_len; unsigned char *buf; size_t buf_len; MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> parse certificate verify" ) ); MBEDTLS_SSL_PROC_CHK( mbedtls_ssl_tls13_fetch_handshake_msg( ssl, MBEDTLS_SSL_HS_CERTIFICATE_VERIFY, &buf, &buf_len ) ); /* Need to calculate the hash of the transcript first * before reading the message since otherwise it gets * included in the transcript */ ret = mbedtls_ssl_get_handshake_transcript( ssl, ssl->handshake->ciphersuite_info->mac, transcript, sizeof( transcript ), &transcript_len ); if( ret != 0 ) { MBEDTLS_SSL_PEND_FATAL_ALERT( MBEDTLS_SSL_ALERT_MSG_INTERNAL_ERROR, MBEDTLS_ERR_SSL_INTERNAL_ERROR ); return( ret ); } MBEDTLS_SSL_DEBUG_BUF( 3, "handshake hash", transcript, transcript_len ); /* Create verify structure */ ssl_tls13_create_verify_structure( transcript, transcript_len, verify_buffer, &verify_buffer_len, ( ssl->conf->endpoint == MBEDTLS_SSL_IS_CLIENT ) ? MBEDTLS_SSL_IS_SERVER : MBEDTLS_SSL_IS_CLIENT ); /* Process the message contents */ MBEDTLS_SSL_PROC_CHK( ssl_tls13_parse_certificate_verify( ssl, buf, buf + buf_len, verify_buffer, verify_buffer_len ) ); mbedtls_ssl_tls13_add_hs_msg_to_checksum( ssl, MBEDTLS_SSL_HS_CERTIFICATE_VERIFY, buf, buf_len ); cleanup: MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= parse certificate verify" ) ); MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_tls13_process_certificate_verify", ret ); return( ret ); #else ((void) ssl); MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) ); return( MBEDTLS_ERR_SSL_INTERNAL_ERROR ); #endif /* MBEDTLS_KEY_EXCHANGE_WITH_CERT_ENABLED */ } /* * * STATE HANDLING: Incoming Certificate, client-side only currently. * */ /* * Implementation */ #if defined(MBEDTLS_KEY_EXCHANGE_ECDHE_ECDSA_ENABLED) #if defined(MBEDTLS_SSL_KEEP_PEER_CERTIFICATE) /* * Structure of Certificate message: * * enum { * X509(0), * RawPublicKey(2), * (255) * } CertificateType; * * struct { * select (certificate_type) { * case RawPublicKey: * * From RFC 7250 ASN.1_subjectPublicKeyInfo * * opaque ASN1_subjectPublicKeyInfo<1..2^24-1>; * case X509: * opaque cert_data<1..2^24-1>; * }; * Extension extensions<0..2^16-1>; * } CertificateEntry; * * struct { * opaque certificate_request_context<0..2^8-1>; * CertificateEntry certificate_list<0..2^24-1>; * } Certificate; * */ /* Parse certificate chain send by the server. */ static int ssl_tls13_parse_certificate( mbedtls_ssl_context *ssl, const unsigned char *buf, const unsigned char *end ) { int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; size_t certificate_request_context_len = 0; size_t certificate_list_len = 0; const unsigned char *p = buf; const unsigned char *certificate_list_end; MBEDTLS_SSL_CHK_BUF_READ_PTR( p, end, 4 ); certificate_request_context_len = p[0]; certificate_list_len = MBEDTLS_GET_UINT24_BE( p, 1 ); p += 4; /* In theory, the certificate list can be up to 2^24 Bytes, but we don't * support anything beyond 2^16 = 64K. */ if( ( certificate_request_context_len != 0 ) || ( certificate_list_len >= 0x10000 ) ) { MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad certificate message" ) ); MBEDTLS_SSL_PEND_FATAL_ALERT( MBEDTLS_SSL_ALERT_MSG_DECODE_ERROR, MBEDTLS_ERR_SSL_DECODE_ERROR ); return( MBEDTLS_ERR_SSL_DECODE_ERROR ); } /* In case we tried to reuse a session but it failed */ if( ssl->session_negotiate->peer_cert != NULL ) { mbedtls_x509_crt_free( ssl->session_negotiate->peer_cert ); mbedtls_free( ssl->session_negotiate->peer_cert ); } if( ( ssl->session_negotiate->peer_cert = mbedtls_calloc( 1, sizeof( mbedtls_x509_crt ) ) ) == NULL ) { MBEDTLS_SSL_DEBUG_MSG( 1, ( "alloc( %" MBEDTLS_PRINTF_SIZET " bytes ) failed", sizeof( mbedtls_x509_crt ) ) ); MBEDTLS_SSL_PEND_FATAL_ALERT( MBEDTLS_SSL_ALERT_MSG_INTERNAL_ERROR, MBEDTLS_ERR_SSL_ALLOC_FAILED ); return( MBEDTLS_ERR_SSL_ALLOC_FAILED ); } mbedtls_x509_crt_init( ssl->session_negotiate->peer_cert ); certificate_list_end = p + certificate_list_len; while( p < certificate_list_end ) { size_t cert_data_len, extensions_len; MBEDTLS_SSL_CHK_BUF_READ_PTR( p, certificate_list_end, 3 ); cert_data_len = MBEDTLS_GET_UINT24_BE( p, 0 ); p += 3; /* In theory, the CRT can be up to 2^24 Bytes, but we don't support * anything beyond 2^16 = 64K. Otherwise as in the TLS 1.2 code, * check that we have a minimum of 128 bytes of data, this is not * clear why we need that though. */ if( ( cert_data_len < 128 ) || ( cert_data_len >= 0x10000 ) ) { MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad Certificate message" ) ); MBEDTLS_SSL_PEND_FATAL_ALERT( MBEDTLS_SSL_ALERT_MSG_DECODE_ERROR, MBEDTLS_ERR_SSL_DECODE_ERROR ); return( MBEDTLS_ERR_SSL_DECODE_ERROR ); } MBEDTLS_SSL_CHK_BUF_READ_PTR( p, certificate_list_end, cert_data_len ); ret = mbedtls_x509_crt_parse_der( ssl->session_negotiate->peer_cert, p, cert_data_len ); switch( ret ) { case 0: /*ok*/ break; case MBEDTLS_ERR_X509_UNKNOWN_SIG_ALG + MBEDTLS_ERR_OID_NOT_FOUND: /* Ignore certificate with an unknown algorithm: maybe a prior certificate was already trusted. */ break; case MBEDTLS_ERR_X509_ALLOC_FAILED: MBEDTLS_SSL_PEND_FATAL_ALERT( MBEDTLS_SSL_ALERT_MSG_INTERNAL_ERROR, MBEDTLS_ERR_X509_ALLOC_FAILED ); MBEDTLS_SSL_DEBUG_RET( 1, " mbedtls_x509_crt_parse_der", ret ); return( ret ); case MBEDTLS_ERR_X509_UNKNOWN_VERSION: MBEDTLS_SSL_PEND_FATAL_ALERT( MBEDTLS_SSL_ALERT_MSG_UNSUPPORTED_CERT, MBEDTLS_ERR_X509_UNKNOWN_VERSION ); MBEDTLS_SSL_DEBUG_RET( 1, " mbedtls_x509_crt_parse_der", ret ); return( ret ); default: MBEDTLS_SSL_PEND_FATAL_ALERT( MBEDTLS_SSL_ALERT_MSG_BAD_CERT, ret ); MBEDTLS_SSL_DEBUG_RET( 1, " mbedtls_x509_crt_parse_der", ret ); return( ret ); } p += cert_data_len; /* Certificate extensions length */ MBEDTLS_SSL_CHK_BUF_READ_PTR( p, certificate_list_end, 2 ); extensions_len = MBEDTLS_GET_UINT16_BE( p, 0 ); p += 2; MBEDTLS_SSL_CHK_BUF_READ_PTR( p, certificate_list_end, extensions_len ); p += extensions_len; } /* Check that all the message is consumed. */ if( p != end ) { MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad Certificate message" ) ); MBEDTLS_SSL_PEND_FATAL_ALERT( MBEDTLS_SSL_ALERT_MSG_DECODE_ERROR, \ MBEDTLS_ERR_SSL_DECODE_ERROR ); return( MBEDTLS_ERR_SSL_DECODE_ERROR ); } MBEDTLS_SSL_DEBUG_CRT( 3, "peer certificate", ssl->session_negotiate->peer_cert ); return( ret ); } #else static int ssl_tls13_parse_certificate( mbedtls_ssl_context *ssl, const unsigned char *buf, const unsigned char *end ) { ((void) ssl); ((void) buf); ((void) end); return( MBEDTLS_ERR_SSL_FEATURE_UNAVAILABLE ); } #endif /* MBEDTLS_SSL_KEEP_PEER_CERTIFICATE */ #endif /* MBEDTLS_KEY_EXCHANGE_ECDHE_ECDSA_ENABLED */ #if defined(MBEDTLS_KEY_EXCHANGE_ECDHE_ECDSA_ENABLED) #if defined(MBEDTLS_SSL_KEEP_PEER_CERTIFICATE) /* Validate certificate chain sent by the server. */ static int ssl_tls13_validate_certificate( mbedtls_ssl_context *ssl ) { int ret = 0; mbedtls_x509_crt *ca_chain; mbedtls_x509_crl *ca_crl; uint32_t verify_result = 0; #if defined(MBEDTLS_SSL_SERVER_NAME_INDICATION) if( ssl->handshake->sni_ca_chain != NULL ) { ca_chain = ssl->handshake->sni_ca_chain; ca_crl = ssl->handshake->sni_ca_crl; } else #endif /* MBEDTLS_SSL_SERVER_NAME_INDICATION */ { ca_chain = ssl->conf->ca_chain; ca_crl = ssl->conf->ca_crl; } /* * Main check: verify certificate */ ret = mbedtls_x509_crt_verify_with_profile( ssl->session_negotiate->peer_cert, ca_chain, ca_crl, ssl->conf->cert_profile, ssl->hostname, &verify_result, ssl->conf->f_vrfy, ssl->conf->p_vrfy ); if( ret != 0 ) { MBEDTLS_SSL_DEBUG_RET( 1, "x509_verify_cert", ret ); } /* * Secondary checks: always done, but change 'ret' only if it was 0 */ #if defined(MBEDTLS_ECP_C) { const mbedtls_pk_context *pk = &ssl->session_negotiate->peer_cert->pk; /* If certificate uses an EC key, make sure the curve is OK */ if( mbedtls_pk_can_do( pk, MBEDTLS_PK_ECKEY ) && mbedtls_ssl_check_curve( ssl, mbedtls_pk_ec( *pk )->grp.id ) != 0 ) { verify_result |= MBEDTLS_X509_BADCERT_BAD_KEY; MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad certificate ( EC key curve )" ) ); if( ret == 0 ) ret = MBEDTLS_ERR_SSL_BAD_CERTIFICATE; } } #endif /* MBEDTLS_ECP_C */ if( mbedtls_ssl_check_cert_usage( ssl->session_negotiate->peer_cert, ssl->handshake->ciphersuite_info, !ssl->conf->endpoint, &verify_result ) != 0 ) { MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad certificate ( usage extensions )" ) ); if( ret == 0 ) ret = MBEDTLS_ERR_SSL_BAD_CERTIFICATE; } if( ca_chain == NULL ) { MBEDTLS_SSL_DEBUG_MSG( 1, ( "got no CA chain" ) ); ret = MBEDTLS_ERR_SSL_CA_CHAIN_REQUIRED; } if( ret != 0 ) { /* The certificate may have been rejected for several reasons. Pick one and send the corresponding alert. Which alert to send may be a subject of debate in some cases. */ if( verify_result & MBEDTLS_X509_BADCERT_OTHER ) MBEDTLS_SSL_PEND_FATAL_ALERT( MBEDTLS_SSL_ALERT_MSG_ACCESS_DENIED, ret ); else if( verify_result & MBEDTLS_X509_BADCERT_CN_MISMATCH ) MBEDTLS_SSL_PEND_FATAL_ALERT( MBEDTLS_SSL_ALERT_MSG_BAD_CERT, ret ); else if( verify_result & ( MBEDTLS_X509_BADCERT_KEY_USAGE | MBEDTLS_X509_BADCERT_EXT_KEY_USAGE | MBEDTLS_X509_BADCERT_NS_CERT_TYPE | MBEDTLS_X509_BADCERT_BAD_PK | MBEDTLS_X509_BADCERT_BAD_KEY ) ) MBEDTLS_SSL_PEND_FATAL_ALERT( MBEDTLS_SSL_ALERT_MSG_UNSUPPORTED_CERT, ret ); else if( verify_result & MBEDTLS_X509_BADCERT_EXPIRED ) MBEDTLS_SSL_PEND_FATAL_ALERT( MBEDTLS_SSL_ALERT_MSG_CERT_EXPIRED, ret ); else if( verify_result & MBEDTLS_X509_BADCERT_REVOKED ) MBEDTLS_SSL_PEND_FATAL_ALERT( MBEDTLS_SSL_ALERT_MSG_CERT_REVOKED, ret ); else if( verify_result & MBEDTLS_X509_BADCERT_NOT_TRUSTED ) MBEDTLS_SSL_PEND_FATAL_ALERT( MBEDTLS_SSL_ALERT_MSG_UNKNOWN_CA, ret ); else MBEDTLS_SSL_PEND_FATAL_ALERT( MBEDTLS_SSL_ALERT_MSG_CERT_UNKNOWN, ret ); } #if defined(MBEDTLS_DEBUG_C) if( verify_result != 0 ) { MBEDTLS_SSL_DEBUG_MSG( 3, ( "! Certificate verification flags %08x", (unsigned int) verify_result ) ); } else { MBEDTLS_SSL_DEBUG_MSG( 3, ( "Certificate verification flags clear" ) ); } #endif /* MBEDTLS_DEBUG_C */ ssl->session_negotiate->verify_result = verify_result; return( ret ); } #else /* MBEDTLS_SSL_KEEP_PEER_CERTIFICATE */ static int ssl_tls13_validate_certificate( mbedtls_ssl_context *ssl ) { ((void) ssl); return( MBEDTLS_ERR_SSL_FEATURE_UNAVAILABLE ); } #endif /* MBEDTLS_SSL_KEEP_PEER_CERTIFICATE */ #endif /* MBEDTLS_KEY_EXCHANGE_ECDHE_ECDSA_ENABLED */ int mbedtls_ssl_tls13_process_certificate( mbedtls_ssl_context *ssl ) { int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> parse certificate" ) ); #if defined(MBEDTLS_KEY_EXCHANGE_ECDHE_ECDSA_ENABLED) unsigned char *buf; size_t buf_len; MBEDTLS_SSL_PROC_CHK( mbedtls_ssl_tls13_fetch_handshake_msg( ssl, MBEDTLS_SSL_HS_CERTIFICATE, &buf, &buf_len ) ); /* Parse the certificate chain sent by the peer. */ MBEDTLS_SSL_PROC_CHK( ssl_tls13_parse_certificate( ssl, buf, buf + buf_len ) ); /* Validate the certificate chain and set the verification results. */ MBEDTLS_SSL_PROC_CHK( ssl_tls13_validate_certificate( ssl ) ); mbedtls_ssl_tls13_add_hs_msg_to_checksum( ssl, MBEDTLS_SSL_HS_CERTIFICATE, buf, buf_len ); cleanup: MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= parse certificate" ) ); #else MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) ); ret = MBEDTLS_ERR_SSL_INTERNAL_ERROR; #endif /* MBEDTLS_KEY_EXCHANGE_ECDHE_ECDSA_ENABLED */ return( ret ); } /* * * STATE HANDLING: Incoming Finished message. */ /* * Implementation */ static int ssl_tls13_preprocess_finished_message( mbedtls_ssl_context *ssl ) { int ret; ret = mbedtls_ssl_tls13_calculate_verify_data( ssl, ssl->handshake->state_local.finished_in.digest, sizeof( ssl->handshake->state_local.finished_in.digest ), &ssl->handshake->state_local.finished_in.digest_len, ssl->conf->endpoint == MBEDTLS_SSL_IS_CLIENT ? MBEDTLS_SSL_IS_SERVER : MBEDTLS_SSL_IS_CLIENT ); if( ret != 0 ) { MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_tls13_calculate_verify_data", ret ); return( ret ); } return( 0 ); } static int ssl_tls13_parse_finished_message( mbedtls_ssl_context *ssl, const unsigned char *buf, const unsigned char *end ) { /* * struct { * opaque verify_data[Hash.length]; * } Finished; */ const unsigned char *expected_verify_data = ssl->handshake->state_local.finished_in.digest; size_t expected_verify_data_len = ssl->handshake->state_local.finished_in.digest_len; /* Structural validation */ if( (size_t)( end - buf ) != expected_verify_data_len ) { MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad finished message" ) ); MBEDTLS_SSL_PEND_FATAL_ALERT( MBEDTLS_SSL_ALERT_MSG_DECODE_ERROR, MBEDTLS_ERR_SSL_DECODE_ERROR ); return( MBEDTLS_ERR_SSL_DECODE_ERROR ); } MBEDTLS_SSL_DEBUG_BUF( 4, "verify_data (self-computed):", expected_verify_data, expected_verify_data_len ); MBEDTLS_SSL_DEBUG_BUF( 4, "verify_data (received message):", buf, expected_verify_data_len ); /* Semantic validation */ if( mbedtls_ct_memcmp( buf, expected_verify_data, expected_verify_data_len ) != 0 ) { MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad finished message" ) ); MBEDTLS_SSL_PEND_FATAL_ALERT( MBEDTLS_SSL_ALERT_MSG_DECRYPT_ERROR, MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE ); return( MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE ); } return( 0 ); } #if defined(MBEDTLS_SSL_CLI_C) static int ssl_tls13_postprocess_server_finished_message( mbedtls_ssl_context *ssl ) { int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; mbedtls_ssl_key_set traffic_keys; mbedtls_ssl_transform *transform_application = NULL; ret = mbedtls_ssl_tls13_key_schedule_stage_application( ssl ); if( ret != 0 ) { MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_tls13_key_schedule_stage_application", ret ); goto cleanup; } ret = mbedtls_ssl_tls13_generate_application_keys( ssl, &traffic_keys ); if( ret != 0 ) { MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_tls13_generate_application_keys", ret ); goto cleanup; } transform_application = mbedtls_calloc( 1, sizeof( mbedtls_ssl_transform ) ); if( transform_application == NULL ) { ret = MBEDTLS_ERR_SSL_ALLOC_FAILED; goto cleanup; } ret = mbedtls_ssl_tls13_populate_transform( transform_application, 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; } ssl->transform_application = transform_application; cleanup: mbedtls_platform_zeroize( &traffic_keys, sizeof( traffic_keys ) ); if( ret != 0 ) { mbedtls_free( transform_application ); MBEDTLS_SSL_PEND_FATAL_ALERT( MBEDTLS_SSL_ALERT_MSG_HANDSHAKE_FAILURE, MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE ); } return( ret ); } #endif /* MBEDTLS_SSL_CLI_C */ static int ssl_tls13_postprocess_finished_message( mbedtls_ssl_context *ssl ) { #if defined(MBEDTLS_SSL_CLI_C) if( ssl->conf->endpoint == MBEDTLS_SSL_IS_CLIENT ) { return( ssl_tls13_postprocess_server_finished_message( ssl ) ); } #else ((void) ssl); #endif /* MBEDTLS_SSL_CLI_C */ return( MBEDTLS_ERR_SSL_INTERNAL_ERROR ); } int mbedtls_ssl_tls13_process_finished_message( mbedtls_ssl_context *ssl ) { int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; unsigned char *buf; size_t buf_len; MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> parse finished message" ) ); /* Preprocessing step: Compute handshake digest */ MBEDTLS_SSL_PROC_CHK( ssl_tls13_preprocess_finished_message( ssl ) ); MBEDTLS_SSL_PROC_CHK( mbedtls_ssl_tls13_fetch_handshake_msg( ssl, MBEDTLS_SSL_HS_FINISHED, &buf, &buf_len ) ); MBEDTLS_SSL_PROC_CHK( ssl_tls13_parse_finished_message( ssl, buf, buf + buf_len ) ); mbedtls_ssl_tls13_add_hs_msg_to_checksum( ssl, MBEDTLS_SSL_HS_FINISHED, buf, buf_len ); MBEDTLS_SSL_PROC_CHK( ssl_tls13_postprocess_finished_message( ssl ) ); cleanup: MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= parse finished message" ) ); return( ret ); } /* * * STATE HANDLING: Write and send Finished message. * */ /* * Implement */ static int ssl_tls13_prepare_finished_message( mbedtls_ssl_context *ssl ) { int ret; /* Compute transcript of handshake up to now. */ ret = mbedtls_ssl_tls13_calculate_verify_data( ssl, ssl->handshake->state_local.finished_out.digest, sizeof( ssl->handshake->state_local.finished_out.digest ), &ssl->handshake->state_local.finished_out.digest_len, ssl->conf->endpoint ); if( ret != 0 ) { MBEDTLS_SSL_DEBUG_RET( 1, "calculate_verify_data failed", ret ); return( ret ); } return( 0 ); } static int ssl_tls13_finalize_finished_message( mbedtls_ssl_context *ssl ) { // TODO: Add back resumption keys calculation after MVP. ((void) ssl); return( 0 ); } static int ssl_tls13_write_finished_message_body( mbedtls_ssl_context *ssl, unsigned char *buf, unsigned char *end, size_t *out_len ) { size_t verify_data_len = ssl->handshake->state_local.finished_out.digest_len; /* * struct { * opaque verify_data[Hash.length]; * } Finished; */ MBEDTLS_SSL_CHK_BUF_PTR( buf, end, verify_data_len ); memcpy( buf, ssl->handshake->state_local.finished_out.digest, verify_data_len ); *out_len = verify_data_len; return( 0 ); } /* Main entry point: orchestrates the other functions */ int mbedtls_ssl_tls13_write_finished_message( mbedtls_ssl_context *ssl ) { int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; unsigned char *buf; size_t buf_len, msg_len; MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> write finished message" ) ); MBEDTLS_SSL_PROC_CHK( ssl_tls13_prepare_finished_message( ssl ) ); MBEDTLS_SSL_PROC_CHK( mbedtls_ssl_tls13_start_handshake_msg( ssl, MBEDTLS_SSL_HS_FINISHED, &buf, &buf_len ) ); MBEDTLS_SSL_PROC_CHK( ssl_tls13_write_finished_message_body( ssl, buf, buf + buf_len, &msg_len ) ); mbedtls_ssl_tls13_add_hs_msg_to_checksum( ssl, MBEDTLS_SSL_HS_FINISHED, buf, msg_len ); MBEDTLS_SSL_PROC_CHK( ssl_tls13_finalize_finished_message( ssl ) ); MBEDTLS_SSL_PROC_CHK( mbedtls_ssl_tls13_finish_handshake_msg( ssl, buf_len, msg_len ) ); MBEDTLS_SSL_PROC_CHK( mbedtls_ssl_flush_output( ssl ) ); cleanup: MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= write finished message" ) ); return( ret ); } void mbedtls_ssl_tls13_handshake_wrapup( mbedtls_ssl_context *ssl ) { MBEDTLS_SSL_DEBUG_MSG( 3, ( "=> handshake wrapup" ) ); /* * Free the previous session and switch to the current one. */ if( ssl->session ) { mbedtls_ssl_session_free( ssl->session ); mbedtls_free( ssl->session ); } ssl->session = ssl->session_negotiate; ssl->session_negotiate = NULL; MBEDTLS_SSL_DEBUG_MSG( 3, ( "<= handshake wrapup" ) ); } #endif /* MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL */ #endif /* MBEDTLS_SSL_TLS_C */