| /* |
| * TLS 1.2 and 1.3 client-side functions |
| * |
| * Copyright The Mbed TLS Contributors |
| * SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later |
| */ |
| |
| #include "common.h" |
| |
| #if defined(MBEDTLS_SSL_CLI_C) |
| #if defined(MBEDTLS_SSL_PROTO_TLS1_3) || defined(MBEDTLS_SSL_PROTO_TLS1_2) |
| |
| #include <string.h> |
| |
| #include "debug_internal.h" |
| #include "mbedtls/error.h" |
| #include "mbedtls/platform.h" |
| |
| #include "ssl_client.h" |
| #include "ssl_misc.h" |
| #include "ssl_tls13_keys.h" |
| #include "ssl_debug_helpers.h" |
| |
| #if defined(MBEDTLS_SSL_SERVER_NAME_INDICATION) |
| MBEDTLS_CHECK_RETURN_CRITICAL |
| static int ssl_write_hostname_ext(mbedtls_ssl_context *ssl, |
| unsigned char *buf, |
| const unsigned char *end, |
| size_t *olen) |
| { |
| unsigned char *p = buf; |
| size_t hostname_len; |
| |
| *olen = 0; |
| |
| if (ssl->hostname == NULL) { |
| return 0; |
| } |
| |
| MBEDTLS_SSL_DEBUG_MSG(3, |
| ("client hello, adding server name extension: %s", |
| ssl->hostname)); |
| |
| hostname_len = strlen(ssl->hostname); |
| |
| MBEDTLS_SSL_CHK_BUF_PTR(p, end, hostname_len + 9); |
| |
| /* |
| * Sect. 3, RFC 6066 (TLS Extensions Definitions) |
| * |
| * In order to provide any of the server names, clients MAY include an |
| * extension of type "server_name" in the (extended) client hello. The |
| * "extension_data" field of this extension SHALL contain |
| * "ServerNameList" where: |
| * |
| * struct { |
| * NameType name_type; |
| * select (name_type) { |
| * case host_name: HostName; |
| * } name; |
| * } ServerName; |
| * |
| * enum { |
| * host_name(0), (255) |
| * } NameType; |
| * |
| * opaque HostName<1..2^16-1>; |
| * |
| * struct { |
| * ServerName server_name_list<1..2^16-1> |
| * } ServerNameList; |
| * |
| */ |
| MBEDTLS_PUT_UINT16_BE(MBEDTLS_TLS_EXT_SERVERNAME, p, 0); |
| p += 2; |
| |
| MBEDTLS_PUT_UINT16_BE(hostname_len + 5, p, 0); |
| p += 2; |
| |
| MBEDTLS_PUT_UINT16_BE(hostname_len + 3, p, 0); |
| p += 2; |
| |
| *p++ = MBEDTLS_BYTE_0(MBEDTLS_TLS_EXT_SERVERNAME_HOSTNAME); |
| |
| MBEDTLS_PUT_UINT16_BE(hostname_len, p, 0); |
| p += 2; |
| |
| memcpy(p, ssl->hostname, hostname_len); |
| |
| *olen = hostname_len + 9; |
| |
| #if defined(MBEDTLS_SSL_PROTO_TLS1_3) |
| mbedtls_ssl_tls13_set_hs_sent_ext_mask(ssl, MBEDTLS_TLS_EXT_SERVERNAME); |
| #endif /* MBEDTLS_SSL_PROTO_TLS1_3 */ |
| return 0; |
| } |
| #endif /* MBEDTLS_SSL_SERVER_NAME_INDICATION */ |
| |
| #if defined(MBEDTLS_SSL_ALPN) |
| /* |
| * ssl_write_alpn_ext() |
| * |
| * Structure of the application_layer_protocol_negotiation extension in |
| * ClientHello: |
| * |
| * opaque ProtocolName<1..2^8-1>; |
| * |
| * struct { |
| * ProtocolName protocol_name_list<2..2^16-1> |
| * } ProtocolNameList; |
| * |
| */ |
| MBEDTLS_CHECK_RETURN_CRITICAL |
| static int ssl_write_alpn_ext(mbedtls_ssl_context *ssl, |
| unsigned char *buf, |
| const unsigned char *end, |
| size_t *out_len) |
| { |
| unsigned char *p = buf; |
| |
| *out_len = 0; |
| |
| if (ssl->conf->alpn_list == NULL) { |
| return 0; |
| } |
| |
| MBEDTLS_SSL_DEBUG_MSG(3, ("client hello, adding alpn extension")); |
| |
| |
| /* Check we have enough space for the extension type (2 bytes), the |
| * extension length (2 bytes) and the protocol_name_list length (2 bytes). |
| */ |
| MBEDTLS_SSL_CHK_BUF_PTR(p, end, 6); |
| MBEDTLS_PUT_UINT16_BE(MBEDTLS_TLS_EXT_ALPN, p, 0); |
| /* Skip writing extension and list length for now */ |
| p += 6; |
| |
| /* |
| * opaque ProtocolName<1..2^8-1>; |
| * |
| * struct { |
| * ProtocolName protocol_name_list<2..2^16-1> |
| * } ProtocolNameList; |
| */ |
| for (const char **cur = ssl->conf->alpn_list; *cur != NULL; cur++) { |
| /* |
| * mbedtls_ssl_conf_set_alpn_protocols() checked that the length of |
| * protocol names is less than 255. |
| */ |
| size_t protocol_name_len = strlen(*cur); |
| |
| MBEDTLS_SSL_CHK_BUF_PTR(p, end, 1 + protocol_name_len); |
| *p++ = (unsigned char) protocol_name_len; |
| memcpy(p, *cur, protocol_name_len); |
| p += protocol_name_len; |
| } |
| |
| *out_len = (size_t) (p - buf); |
| |
| /* List length = *out_len - 2 (ext_type) - 2 (ext_len) - 2 (list_len) */ |
| MBEDTLS_PUT_UINT16_BE(*out_len - 6, buf, 4); |
| |
| /* Extension length = *out_len - 2 (ext_type) - 2 (ext_len) */ |
| MBEDTLS_PUT_UINT16_BE(*out_len - 4, buf, 2); |
| |
| #if defined(MBEDTLS_SSL_PROTO_TLS1_3) |
| mbedtls_ssl_tls13_set_hs_sent_ext_mask(ssl, MBEDTLS_TLS_EXT_ALPN); |
| #endif /* MBEDTLS_SSL_PROTO_TLS1_3 */ |
| return 0; |
| } |
| #endif /* MBEDTLS_SSL_ALPN */ |
| |
| #if defined(MBEDTLS_SSL_TLS1_2_SOME_ECC) || \ |
| defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_EPHEMERAL_ENABLED) |
| /* |
| * Function for writing a supported groups (TLS 1.3) or supported elliptic |
| * curves (TLS 1.2) extension. |
| * |
| * The "extension_data" field of a supported groups extension contains a |
| * "NamedGroupList" value (TLS 1.3 RFC8446): |
| * 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; |
| * |
| * The "extension_data" field of a supported elliptic curves extension contains |
| * a "NamedCurveList" value (TLS 1.2 RFC 8422): |
| * enum { |
| * deprecated(1..22), |
| * secp256r1 (23), secp384r1 (24), secp521r1 (25), |
| * x25519(29), x448(30), |
| * reserved (0xFE00..0xFEFF), |
| * deprecated(0xFF01..0xFF02), |
| * (0xFFFF) |
| * } NamedCurve; |
| * struct { |
| * NamedCurve named_curve_list<2..2^16-1> |
| * } NamedCurveList; |
| * |
| * The TLS 1.3 supported groups extension was defined to be a compatible |
| * generalization of the TLS 1.2 supported elliptic curves extension. They both |
| * share the same extension identifier. |
| * |
| */ |
| #define SSL_WRITE_SUPPORTED_GROUPS_EXT_TLS1_2_FLAG 1 |
| #define SSL_WRITE_SUPPORTED_GROUPS_EXT_TLS1_3_FLAG 2 |
| |
| MBEDTLS_CHECK_RETURN_CRITICAL |
| static int ssl_write_supported_groups_ext(mbedtls_ssl_context *ssl, |
| unsigned char *buf, |
| const unsigned char *end, |
| int flags, |
| size_t *out_len) |
| { |
| unsigned char *p = buf; |
| unsigned char *named_group_list; /* Start of named_group_list */ |
| size_t named_group_list_len; /* Length of named_group_list */ |
| const uint16_t *group_list = mbedtls_ssl_get_groups(ssl); |
| |
| *out_len = 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 = p; |
| |
| if (group_list == NULL) { |
| return MBEDTLS_ERR_SSL_BAD_CONFIG; |
| } |
| |
| for (; *group_list != 0; group_list++) { |
| int propose_group = 0; |
| |
| MBEDTLS_SSL_DEBUG_MSG(3, ("got supported group(%04x)", *group_list)); |
| |
| #if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_EPHEMERAL_ENABLED) |
| if (flags & SSL_WRITE_SUPPORTED_GROUPS_EXT_TLS1_3_FLAG) { |
| #if defined(PSA_WANT_ALG_ECDH) |
| if (mbedtls_ssl_tls13_named_group_is_ecdhe(*group_list) && |
| (mbedtls_ssl_get_ecp_group_id_from_tls_id(*group_list) != |
| MBEDTLS_ECP_DP_NONE)) { |
| propose_group = 1; |
| } |
| #endif |
| #if defined(PSA_WANT_ALG_FFDH) |
| if (mbedtls_ssl_tls13_named_group_is_ffdh(*group_list)) { |
| propose_group = 1; |
| } |
| #endif |
| } |
| #endif /* MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_EPHEMERAL_ENABLED */ |
| |
| #if defined(MBEDTLS_SSL_TLS1_2_SOME_ECC) |
| if ((flags & SSL_WRITE_SUPPORTED_GROUPS_EXT_TLS1_2_FLAG) && |
| mbedtls_ssl_tls12_named_group_is_ecdhe(*group_list) && |
| (mbedtls_ssl_get_ecp_group_id_from_tls_id(*group_list) != |
| MBEDTLS_ECP_DP_NONE)) { |
| propose_group = 1; |
| } |
| #endif /* MBEDTLS_SSL_TLS1_2_SOME_ECC */ |
| |
| if (propose_group) { |
| MBEDTLS_SSL_CHK_BUF_PTR(p, end, 2); |
| MBEDTLS_PUT_UINT16_BE(*group_list, p, 0); |
| p += 2; |
| MBEDTLS_SSL_DEBUG_MSG(3, ("NamedGroup: %s ( %x )", |
| mbedtls_ssl_named_group_to_str(*group_list), |
| *group_list)); |
| } |
| } |
| |
| /* Length of named_group_list */ |
| named_group_list_len = (size_t) (p - named_group_list); |
| 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); |
| |
| *out_len = (size_t) (p - buf); |
| |
| #if defined(MBEDTLS_SSL_PROTO_TLS1_3) |
| mbedtls_ssl_tls13_set_hs_sent_ext_mask( |
| ssl, MBEDTLS_TLS_EXT_SUPPORTED_GROUPS); |
| #endif /* MBEDTLS_SSL_PROTO_TLS1_3 */ |
| |
| return 0; |
| } |
| #endif /* MBEDTLS_SSL_TLS1_2_SOME_ECC || |
| MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_EPHEMERAL_ENABLED */ |
| |
| MBEDTLS_CHECK_RETURN_CRITICAL |
| static int ssl_write_client_hello_cipher_suites( |
| mbedtls_ssl_context *ssl, |
| unsigned char *buf, |
| unsigned char *end, |
| int *tls12_uses_ec, |
| size_t *out_len) |
| { |
| unsigned char *p = buf; |
| const int *ciphersuite_list; |
| unsigned char *cipher_suites; /* Start of the cipher_suites list */ |
| size_t cipher_suites_len; |
| |
| *tls12_uses_ec = 0; |
| *out_len = 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 |
| * CipherSuite cipher_suites<2..2^16-2>; |
| */ |
| cipher_suites = 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 (mbedtls_ssl_validate_ciphersuite(ssl, ciphersuite_info, |
| ssl->handshake->min_tls_version, |
| ssl->tls_version) != 0) { |
| continue; |
| } |
| |
| #if defined(MBEDTLS_SSL_PROTO_TLS1_2) && \ |
| (defined(MBEDTLS_KEY_EXCHANGE_SOME_ECDH_OR_ECDHE_1_2_ENABLED) || \ |
| defined(MBEDTLS_KEY_EXCHANGE_ECDSA_CERT_REQ_ALLOWED_ENABLED) || \ |
| defined(MBEDTLS_KEY_EXCHANGE_ECJPAKE_ENABLED)) |
| *tls12_uses_ec |= mbedtls_ssl_ciphersuite_uses_ec(ciphersuite_info); |
| #endif |
| |
| 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; |
| } |
| |
| /* |
| * Add TLS_EMPTY_RENEGOTIATION_INFO_SCSV |
| */ |
| int renegotiating = 0; |
| #if defined(MBEDTLS_SSL_RENEGOTIATION) |
| renegotiating = (ssl->renego_status != MBEDTLS_SSL_INITIAL_HANDSHAKE); |
| #endif |
| if (!renegotiating) { |
| MBEDTLS_SSL_DEBUG_MSG(3, ("adding EMPTY_RENEGOTIATION_INFO_SCSV")); |
| MBEDTLS_SSL_CHK_BUF_PTR(p, end, 2); |
| MBEDTLS_PUT_UINT16_BE(MBEDTLS_SSL_EMPTY_RENEGOTIATION_INFO, p, 0); |
| p += 2; |
| } |
| |
| /* Write the cipher_suites length in number of bytes */ |
| cipher_suites_len = (size_t) (p - cipher_suites); |
| 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. */ |
| *out_len = (size_t) (p - buf); |
| |
| return 0; |
| } |
| |
| /* |
| * Structure of the TLS 1.3 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; |
| * |
| * Structure of the (D)TLS 1.2 ClientHello message: |
| * |
| * struct { |
| * ProtocolVersion client_version; |
| * Random random; |
| * SessionID session_id; |
| * opaque cookie<0..2^8-1>; // DTLS 1.2 ONLY |
| * CipherSuite cipher_suites<2..2^16-2>; |
| * CompressionMethod compression_methods<1..2^8-1>; |
| * select (extensions_present) { |
| * case false: |
| * struct {}; |
| * case true: |
| * Extension extensions<0..2^16-1>; |
| * }; |
| * } ClientHello; |
| */ |
| MBEDTLS_CHECK_RETURN_CRITICAL |
| static int ssl_write_client_hello_body(mbedtls_ssl_context *ssl, |
| unsigned char *buf, |
| unsigned char *end, |
| size_t *out_len, |
| size_t *binders_len) |
| { |
| int ret; |
| mbedtls_ssl_handshake_params *handshake = ssl->handshake; |
| unsigned char *p = buf; |
| unsigned char *p_extensions_len; /* Pointer to extensions length */ |
| size_t output_len; /* Length of buffer used by function */ |
| size_t extensions_len; /* Length of the list of extensions*/ |
| int tls12_uses_ec = 0; |
| |
| *out_len = 0; |
| *binders_len = 0; |
| |
| #if defined(MBEDTLS_SSL_PROTO_TLS1_2) |
| unsigned char propose_tls12 = |
| (handshake->min_tls_version <= MBEDTLS_SSL_VERSION_TLS1_2) |
| && |
| (MBEDTLS_SSL_VERSION_TLS1_2 <= ssl->tls_version); |
| #endif |
| #if defined(MBEDTLS_SSL_PROTO_TLS1_3) |
| unsigned char propose_tls13 = |
| (handshake->min_tls_version <= MBEDTLS_SSL_VERSION_TLS1_3) |
| && |
| (MBEDTLS_SSL_VERSION_TLS1_3 <= ssl->tls_version); |
| #endif |
| |
| /* |
| * Write client_version (TLS 1.2) or legacy_version (TLS 1.3) |
| * |
| * In all cases this is the TLS 1.2 version. |
| */ |
| MBEDTLS_SSL_CHK_BUF_PTR(p, end, 2); |
| mbedtls_ssl_write_version(p, ssl->conf->transport, |
| MBEDTLS_SSL_VERSION_TLS1_2); |
| p += 2; |
| |
| /* ... |
| * Random random; |
| * ... |
| * |
| * The random bytes have been prepared by ssl_prepare_client_hello() into |
| * the handshake->randbytes buffer and are copied here into the output |
| * buffer. |
| */ |
| MBEDTLS_SSL_CHK_BUF_PTR(p, end, MBEDTLS_CLIENT_HELLO_RANDOM_LEN); |
| memcpy(p, 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; |
| |
| /* TLS 1.2: |
| * ... |
| * SessionID session_id; |
| * ... |
| * with |
| * opaque SessionID<0..32>; |
| * |
| * TLS 1.3: |
| * ... |
| * opaque legacy_session_id<0..32>; |
| * ... |
| * |
| * The (legacy) session identifier bytes have been prepared by |
| * ssl_prepare_client_hello() into the ssl->session_negotiate->id buffer |
| * and are copied here into the output buffer. |
| */ |
| MBEDTLS_SSL_CHK_BUF_PTR(p, end, ssl->session_negotiate->id_len + 1); |
| *p++ = (unsigned char) ssl->session_negotiate->id_len; |
| memcpy(p, ssl->session_negotiate->id, ssl->session_negotiate->id_len); |
| p += ssl->session_negotiate->id_len; |
| |
| MBEDTLS_SSL_DEBUG_BUF(3, "session id", ssl->session_negotiate->id, |
| ssl->session_negotiate->id_len); |
| |
| /* DTLS 1.2 ONLY |
| * ... |
| * opaque cookie<0..2^8-1>; |
| * ... |
| */ |
| #if defined(MBEDTLS_SSL_PROTO_TLS1_2) && defined(MBEDTLS_SSL_PROTO_DTLS) |
| if (ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM) { |
| #if !defined(MBEDTLS_SSL_PROTO_TLS1_3) |
| uint8_t cookie_len = 0; |
| #else |
| uint16_t cookie_len = 0; |
| #endif /* !MBEDTLS_SSL_PROTO_TLS1_3 */ |
| |
| if (handshake->cookie != NULL) { |
| MBEDTLS_SSL_DEBUG_BUF(3, "client hello, cookie", |
| handshake->cookie, |
| handshake->cookie_len); |
| cookie_len = handshake->cookie_len; |
| } |
| |
| MBEDTLS_SSL_CHK_BUF_PTR(p, end, cookie_len + 1); |
| *p++ = (unsigned char) cookie_len; |
| if (cookie_len > 0) { |
| memcpy(p, handshake->cookie, cookie_len); |
| p += cookie_len; |
| } |
| } |
| #endif /* MBEDTLS_SSL_PROTO_TLS1_2 && MBEDTLS_SSL_PROTO_DTLS */ |
| |
| /* Write cipher_suites */ |
| ret = ssl_write_client_hello_cipher_suites(ssl, p, end, |
| &tls12_uses_ec, |
| &output_len); |
| if (ret != 0) { |
| return ret; |
| } |
| p += output_len; |
| |
| /* Write legacy_compression_methods (TLS 1.3) or |
| * compression_methods (TLS 1.2) |
| * |
| * 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. |
| * |
| * For TLS 1.2 ClientHello, for security reasons we do not support |
| * compression anymore, thus also just the 'null' compression method. |
| */ |
| MBEDTLS_SSL_CHK_BUF_PTR(p, end, 2); |
| *p++ = 1; |
| *p++ = MBEDTLS_SSL_COMPRESS_NULL; |
| |
| /* Write extensions */ |
| |
| #if defined(MBEDTLS_SSL_PROTO_TLS1_3) |
| /* Keeping track of the included extensions */ |
| handshake->sent_extensions = MBEDTLS_SSL_EXT_MASK_NONE; |
| #endif |
| |
| /* First write extensions, then the total length */ |
| MBEDTLS_SSL_CHK_BUF_PTR(p, end, 2); |
| p_extensions_len = p; |
| p += 2; |
| |
| #if defined(MBEDTLS_SSL_SERVER_NAME_INDICATION) |
| /* Write server name extension */ |
| ret = ssl_write_hostname_ext(ssl, p, end, &output_len); |
| if (ret != 0) { |
| return ret; |
| } |
| p += output_len; |
| #endif /* MBEDTLS_SSL_SERVER_NAME_INDICATION */ |
| |
| #if defined(MBEDTLS_SSL_ALPN) |
| ret = ssl_write_alpn_ext(ssl, p, end, &output_len); |
| if (ret != 0) { |
| return ret; |
| } |
| p += output_len; |
| #endif /* MBEDTLS_SSL_ALPN */ |
| |
| #if defined(MBEDTLS_SSL_PROTO_TLS1_3) |
| if (propose_tls13) { |
| ret = mbedtls_ssl_tls13_write_client_hello_exts(ssl, p, end, |
| &output_len); |
| if (ret != 0) { |
| return ret; |
| } |
| p += output_len; |
| } |
| #endif |
| |
| #if defined(MBEDTLS_SSL_TLS1_2_SOME_ECC) || \ |
| defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_EPHEMERAL_ENABLED) |
| { |
| int ssl_write_supported_groups_ext_flags = 0; |
| |
| #if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_EPHEMERAL_ENABLED) |
| if (propose_tls13 && mbedtls_ssl_conf_tls13_is_some_ephemeral_enabled(ssl)) { |
| ssl_write_supported_groups_ext_flags |= |
| SSL_WRITE_SUPPORTED_GROUPS_EXT_TLS1_3_FLAG; |
| } |
| #endif |
| #if defined(MBEDTLS_SSL_TLS1_2_SOME_ECC) |
| if (propose_tls12 && tls12_uses_ec) { |
| ssl_write_supported_groups_ext_flags |= |
| SSL_WRITE_SUPPORTED_GROUPS_EXT_TLS1_2_FLAG; |
| } |
| #endif |
| if (ssl_write_supported_groups_ext_flags != 0) { |
| ret = ssl_write_supported_groups_ext(ssl, p, end, |
| ssl_write_supported_groups_ext_flags, |
| &output_len); |
| if (ret != 0) { |
| return ret; |
| } |
| p += output_len; |
| } |
| } |
| #endif /* MBEDTLS_SSL_TLS1_2_SOME_ECC || |
| MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_EPHEMERAL_ENABLED */ |
| |
| #if defined(MBEDTLS_SSL_HANDSHAKE_WITH_CERT_ENABLED) |
| int write_sig_alg_ext = 0; |
| #if defined(MBEDTLS_SSL_PROTO_TLS1_3) |
| write_sig_alg_ext = write_sig_alg_ext || |
| (propose_tls13 && mbedtls_ssl_conf_tls13_is_ephemeral_enabled(ssl)); |
| #endif |
| #if defined(MBEDTLS_SSL_PROTO_TLS1_2) |
| write_sig_alg_ext = write_sig_alg_ext || propose_tls12; |
| #endif |
| |
| if (write_sig_alg_ext) { |
| ret = mbedtls_ssl_write_sig_alg_ext(ssl, p, end, &output_len); |
| if (ret != 0) { |
| return ret; |
| } |
| p += output_len; |
| } |
| #endif /* MBEDTLS_SSL_HANDSHAKE_WITH_CERT_ENABLED */ |
| |
| #if defined(MBEDTLS_SSL_PROTO_TLS1_2) |
| if (propose_tls12) { |
| ret = mbedtls_ssl_tls12_write_client_hello_exts(ssl, p, end, |
| tls12_uses_ec, |
| &output_len); |
| if (ret != 0) { |
| return ret; |
| } |
| p += output_len; |
| } |
| #endif /* MBEDTLS_SSL_PROTO_TLS1_2 */ |
| |
| #if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_PSK_ENABLED) |
| /* The "pre_shared_key" extension (RFC 8446 Section 4.2.11) |
| * MUST be the last extension in the ClientHello. |
| */ |
| if (propose_tls13 && mbedtls_ssl_conf_tls13_is_some_psk_enabled(ssl)) { |
| ret = mbedtls_ssl_tls13_write_identities_of_pre_shared_key_ext( |
| ssl, p, end, &output_len, binders_len); |
| if (ret != 0) { |
| return ret; |
| } |
| p += output_len; |
| } |
| #endif /* MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_PSK_ENABLED */ |
| |
| /* Write the length of the list of extensions. */ |
| extensions_len = (size_t) (p - p_extensions_len) - 2; |
| |
| if (extensions_len == 0) { |
| p = p_extensions_len; |
| } else { |
| MBEDTLS_PUT_UINT16_BE(extensions_len, p_extensions_len, 0); |
| MBEDTLS_SSL_DEBUG_MSG(3, ("client hello, total extension length: %" \ |
| MBEDTLS_PRINTF_SIZET, extensions_len)); |
| MBEDTLS_SSL_DEBUG_BUF(3, "client hello extensions", |
| p_extensions_len, extensions_len); |
| } |
| |
| *out_len = (size_t) (p - buf); |
| return 0; |
| } |
| |
| MBEDTLS_CHECK_RETURN_CRITICAL |
| static int ssl_generate_random(mbedtls_ssl_context *ssl) |
| { |
| int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; |
| unsigned char *randbytes = ssl->handshake->randbytes; |
| size_t gmt_unix_time_len = 0; |
| |
| /* |
| * Generate the random bytes |
| * |
| * TLS 1.2 case: |
| * struct { |
| * uint32 gmt_unix_time; |
| * opaque random_bytes[28]; |
| * } Random; |
| * |
| * TLS 1.3 case: |
| * opaque Random[32]; |
| */ |
| if (ssl->tls_version == MBEDTLS_SSL_VERSION_TLS1_2) { |
| #if defined(MBEDTLS_HAVE_TIME) |
| mbedtls_time_t gmt_unix_time = mbedtls_time(NULL); |
| MBEDTLS_PUT_UINT32_BE(gmt_unix_time, randbytes, 0); |
| gmt_unix_time_len = 4; |
| |
| MBEDTLS_SSL_DEBUG_MSG(3, |
| ("client hello, current time: %" MBEDTLS_PRINTF_LONGLONG, |
| (long long) gmt_unix_time)); |
| #endif /* MBEDTLS_HAVE_TIME */ |
| } |
| |
| ret = ssl->conf->f_rng(ssl->conf->p_rng, |
| randbytes + gmt_unix_time_len, |
| MBEDTLS_CLIENT_HELLO_RANDOM_LEN - gmt_unix_time_len); |
| return ret; |
| } |
| |
| MBEDTLS_CHECK_RETURN_CRITICAL |
| static int ssl_prepare_client_hello(mbedtls_ssl_context *ssl) |
| { |
| int ret; |
| size_t session_id_len; |
| mbedtls_ssl_session *session_negotiate = ssl->session_negotiate; |
| |
| if (session_negotiate == NULL) { |
| return MBEDTLS_ERR_SSL_INTERNAL_ERROR; |
| } |
| |
| #if defined(MBEDTLS_SSL_PROTO_TLS1_3) && \ |
| defined(MBEDTLS_SSL_SESSION_TICKETS) && \ |
| defined(MBEDTLS_HAVE_TIME) |
| |
| /* Check if a tls13 ticket has been configured. */ |
| if (ssl->handshake->resume != 0 && |
| session_negotiate->tls_version == MBEDTLS_SSL_VERSION_TLS1_3 && |
| session_negotiate->ticket != NULL) { |
| mbedtls_ms_time_t now = mbedtls_ms_time(); |
| mbedtls_ms_time_t age = now - session_negotiate->ticket_reception_time; |
| if (age < 0 || |
| age > (mbedtls_ms_time_t) session_negotiate->ticket_lifetime * 1000) { |
| /* Without valid ticket, disable session resumption.*/ |
| MBEDTLS_SSL_DEBUG_MSG( |
| 3, ("Ticket expired, disable session resumption")); |
| ssl->handshake->resume = 0; |
| } |
| } |
| #endif /* MBEDTLS_SSL_PROTO_TLS1_3 && |
| MBEDTLS_SSL_SESSION_TICKETS && |
| MBEDTLS_HAVE_TIME */ |
| |
| /* Bet on the highest configured version if we are not in a TLS 1.2 |
| * renegotiation or session resumption. |
| */ |
| #if defined(MBEDTLS_SSL_RENEGOTIATION) |
| if (ssl->renego_status != MBEDTLS_SSL_INITIAL_HANDSHAKE) { |
| ssl->handshake->min_tls_version = ssl->tls_version; |
| } else |
| #endif |
| { |
| if (ssl->handshake->resume) { |
| ssl->tls_version = session_negotiate->tls_version; |
| ssl->handshake->min_tls_version = ssl->tls_version; |
| } else { |
| ssl->handshake->min_tls_version = ssl->conf->min_tls_version; |
| } |
| } |
| |
| /* |
| * Generate the random bytes, except when responding to a verify request |
| * where we MUST reuse the previously generated random bytes |
| * (RFC 6347 4.2.1). |
| */ |
| #if defined(MBEDTLS_SSL_PROTO_DTLS) |
| if ((ssl->conf->transport != MBEDTLS_SSL_TRANSPORT_DATAGRAM) || |
| (ssl->handshake->cookie == NULL)) |
| #endif |
| { |
| #if defined(MBEDTLS_SSL_PROTO_TLS1_3) |
| if (!ssl->handshake->hello_retry_request_flag) |
| #endif |
| { |
| ret = ssl_generate_random(ssl); |
| if (ret != 0) { |
| MBEDTLS_SSL_DEBUG_RET(1, "Random bytes generation failed", ret); |
| return ret; |
| } |
| } |
| } |
| |
| /* |
| * Prepare session identifier. At that point, the length of the session |
| * identifier in the SSL context `ssl->session_negotiate->id_len` is equal |
| * to zero, except in the case of a TLS 1.2 session renegotiation or |
| * session resumption. |
| */ |
| session_id_len = session_negotiate->id_len; |
| |
| #if defined(MBEDTLS_SSL_PROTO_TLS1_2) |
| if (ssl->tls_version == MBEDTLS_SSL_VERSION_TLS1_2) { |
| if (session_id_len < 16 || session_id_len > 32 || |
| #if defined(MBEDTLS_SSL_RENEGOTIATION) |
| ssl->renego_status != MBEDTLS_SSL_INITIAL_HANDSHAKE || |
| #endif |
| ssl->handshake->resume == 0) { |
| session_id_len = 0; |
| } |
| |
| #if defined(MBEDTLS_SSL_SESSION_TICKETS) |
| /* |
| * RFC 5077 section 3.4: "When presenting a ticket, the client MAY |
| * generate and include a Session ID in the TLS ClientHello." |
| */ |
| int renegotiating = 0; |
| #if defined(MBEDTLS_SSL_RENEGOTIATION) |
| if (ssl->renego_status != MBEDTLS_SSL_INITIAL_HANDSHAKE) { |
| renegotiating = 1; |
| } |
| #endif |
| if (!renegotiating) { |
| if ((session_negotiate->ticket != NULL) && |
| (session_negotiate->ticket_len != 0)) { |
| session_id_len = 32; |
| } |
| } |
| #endif /* MBEDTLS_SSL_SESSION_TICKETS */ |
| } |
| #endif /* MBEDTLS_SSL_PROTO_TLS1_2 */ |
| |
| #if defined(MBEDTLS_SSL_TLS1_3_COMPATIBILITY_MODE) |
| if (ssl->tls_version == MBEDTLS_SSL_VERSION_TLS1_3) { |
| /* |
| * Create a legacy session identifier for the purpose of middlebox |
| * compatibility only if one has not been created already, which is |
| * the case if we are here for the TLS 1.3 second ClientHello. |
| * |
| * Versions of TLS before TLS 1.3 supported a "session resumption" |
| * feature which has been merged with pre-shared keys in TLS 1.3 |
| * 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 ). |
| */ |
| session_id_len = 32; |
| } |
| #endif /* MBEDTLS_SSL_TLS1_3_COMPATIBILITY_MODE */ |
| |
| if (session_id_len != session_negotiate->id_len) { |
| session_negotiate->id_len = session_id_len; |
| if (session_id_len > 0) { |
| ret = ssl->conf->f_rng(ssl->conf->p_rng, |
| session_negotiate->id, |
| session_id_len); |
| if (ret != 0) { |
| MBEDTLS_SSL_DEBUG_RET(1, "creating session id failed", ret); |
| return ret; |
| } |
| } |
| } |
| |
| #if defined(MBEDTLS_SSL_PROTO_TLS1_3) && \ |
| defined(MBEDTLS_SSL_SESSION_TICKETS) && \ |
| defined(MBEDTLS_SSL_SERVER_NAME_INDICATION) |
| if (ssl->tls_version == MBEDTLS_SSL_VERSION_TLS1_3 && |
| ssl->handshake->resume) { |
| int hostname_mismatch = ssl->hostname != NULL || |
| session_negotiate->hostname != NULL; |
| if (ssl->hostname != NULL && session_negotiate->hostname != NULL) { |
| hostname_mismatch = strcmp( |
| ssl->hostname, session_negotiate->hostname) != 0; |
| } |
| |
| if (hostname_mismatch) { |
| MBEDTLS_SSL_DEBUG_MSG( |
| 1, ("Hostname mismatch the session ticket, " |
| "disable session resumption.")); |
| return MBEDTLS_ERR_SSL_BAD_INPUT_DATA; |
| } |
| } else { |
| return mbedtls_ssl_session_set_hostname(session_negotiate, |
| ssl->hostname); |
| } |
| #endif /* MBEDTLS_SSL_PROTO_TLS1_3 && |
| MBEDTLS_SSL_SESSION_TICKETS && |
| MBEDTLS_SSL_SERVER_NAME_INDICATION */ |
| |
| return 0; |
| } |
| /* |
| * Write ClientHello handshake message. |
| * Handler for MBEDTLS_SSL_CLIENT_HELLO |
| */ |
| int mbedtls_ssl_write_client_hello(mbedtls_ssl_context *ssl) |
| { |
| int ret = 0; |
| unsigned char *buf; |
| size_t buf_len, msg_len, binders_len; |
| |
| MBEDTLS_SSL_DEBUG_MSG(2, ("=> write client hello")); |
| |
| MBEDTLS_SSL_PROC_CHK(ssl_prepare_client_hello(ssl)); |
| |
| MBEDTLS_SSL_PROC_CHK(mbedtls_ssl_start_handshake_msg( |
| ssl, MBEDTLS_SSL_HS_CLIENT_HELLO, |
| &buf, &buf_len)); |
| |
| MBEDTLS_SSL_PROC_CHK(ssl_write_client_hello_body(ssl, buf, |
| buf + buf_len, |
| &msg_len, |
| &binders_len)); |
| |
| #if defined(MBEDTLS_SSL_PROTO_TLS1_2) && defined(MBEDTLS_SSL_PROTO_DTLS) |
| if (ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM) { |
| ssl->out_msglen = msg_len + 4; |
| mbedtls_ssl_send_flight_completed(ssl); |
| |
| /* |
| * The two functions below may try to send data on the network and |
| * can return with the MBEDTLS_ERR_SSL_WANT_READ error code when they |
| * fail to do so and the transmission has to be retried later. In that |
| * case as in fatal error cases, we return immediately. But we must have |
| * set the handshake state to the next state at that point to ensure |
| * that we will not write and send again a ClientHello when we |
| * eventually succeed in sending the pending data. |
| */ |
| mbedtls_ssl_handshake_set_state(ssl, MBEDTLS_SSL_SERVER_HELLO); |
| |
| if ((ret = mbedtls_ssl_write_handshake_msg(ssl)) != 0) { |
| MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_ssl_write_handshake_msg", ret); |
| return ret; |
| } |
| |
| if ((ret = mbedtls_ssl_flight_transmit(ssl)) != 0) { |
| MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_ssl_flight_transmit", ret); |
| return ret; |
| } |
| } else |
| #endif /* MBEDTLS_SSL_PROTO_TLS1_2 && MBEDTLS_SSL_PROTO_DTLS */ |
| { |
| |
| ret = mbedtls_ssl_add_hs_hdr_to_checksum(ssl, |
| MBEDTLS_SSL_HS_CLIENT_HELLO, |
| msg_len); |
| if (ret != 0) { |
| MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_ssl_add_hs_hdr_to_checksum", ret); |
| return ret; |
| } |
| ret = ssl->handshake->update_checksum(ssl, buf, msg_len - binders_len); |
| if (ret != 0) { |
| MBEDTLS_SSL_DEBUG_RET(1, "update_checksum", ret); |
| return ret; |
| } |
| #if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_PSK_ENABLED) |
| if (binders_len > 0) { |
| MBEDTLS_SSL_PROC_CHK( |
| mbedtls_ssl_tls13_write_binders_of_pre_shared_key_ext( |
| ssl, buf + msg_len - binders_len, buf + msg_len)); |
| ret = ssl->handshake->update_checksum(ssl, buf + msg_len - binders_len, |
| binders_len); |
| if (ret != 0) { |
| MBEDTLS_SSL_DEBUG_RET(1, "update_checksum", ret); |
| return ret; |
| } |
| } |
| #endif /* MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_PSK_ENABLED */ |
| |
| MBEDTLS_SSL_PROC_CHK(mbedtls_ssl_finish_handshake_msg(ssl, |
| buf_len, |
| msg_len)); |
| |
| /* |
| * Set next state. Note that if TLS 1.3 is proposed, this may be |
| * overwritten by mbedtls_ssl_tls13_finalize_client_hello(). |
| */ |
| mbedtls_ssl_handshake_set_state(ssl, MBEDTLS_SSL_SERVER_HELLO); |
| |
| #if defined(MBEDTLS_SSL_PROTO_TLS1_3) |
| if (ssl->handshake->min_tls_version <= MBEDTLS_SSL_VERSION_TLS1_3 && |
| MBEDTLS_SSL_VERSION_TLS1_3 <= ssl->tls_version) { |
| ret = mbedtls_ssl_tls13_finalize_client_hello(ssl); |
| } |
| #endif |
| } |
| |
| #if defined(MBEDTLS_SSL_PROTO_TLS1_3) |
| MBEDTLS_SSL_PRINT_EXTS( |
| 3, MBEDTLS_SSL_HS_CLIENT_HELLO, ssl->handshake->sent_extensions); |
| #endif |
| |
| cleanup: |
| |
| MBEDTLS_SSL_DEBUG_MSG(2, ("<= write client hello")); |
| return ret; |
| } |
| |
| #endif /* MBEDTLS_SSL_PROTO_TLS1_3 || MBEDTLS_SSL_PROTO_TLS1_2 */ |
| #endif /* MBEDTLS_SSL_CLI_C */ |
