/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com) * All rights reserved. * * This package is an SSL implementation written * by Eric Young (eay@cryptsoft.com). * The implementation was written so as to conform with Netscapes SSL. * * This library is free for commercial and non-commercial use as long as * the following conditions are aheared to. The following conditions * apply to all code found in this distribution, be it the RC4, RSA, * lhash, DES, etc., code; not just the SSL code. The SSL documentation * included with this distribution is covered by the same copyright terms * except that the holder is Tim Hudson (tjh@cryptsoft.com). * * Copyright remains Eric Young's, and as such any Copyright notices in * the code are not to be removed. * If this package is used in a product, Eric Young should be given attribution * as the author of the parts of the library used. * This can be in the form of a textual message at program startup or * in documentation (online or textual) provided with the package. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. All advertising materials mentioning features or use of this software * must display the following acknowledgement: * "This product includes cryptographic software written by * Eric Young (eay@cryptsoft.com)" * The word 'cryptographic' can be left out if the rouines from the library * being used are not cryptographic related :-). * 4. If you include any Windows specific code (or a derivative thereof) from * the apps directory (application code) you must include an acknowledgement: * "This product includes software written by Tim Hudson (tjh@cryptsoft.com)" * * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. * * The licence and distribution terms for any publically available version or * derivative of this code cannot be changed. i.e. this code cannot simply be * copied and put under another distribution licence * [including the GNU Public Licence.] */ /* ==================================================================== * Copyright (c) 1998-2007 The OpenSSL Project. All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in * the documentation and/or other materials provided with the * distribution. * * 3. All advertising materials mentioning features or use of this * software must display the following acknowledgment: * "This product includes software developed by the OpenSSL Project * for use in the OpenSSL Toolkit. (http://www.openssl.org/)" * * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to * endorse or promote products derived from this software without * prior written permission. For written permission, please contact * openssl-core@openssl.org. * * 5. Products derived from this software may not be called "OpenSSL" * nor may "OpenSSL" appear in their names without prior written * permission of the OpenSSL Project. * * 6. Redistributions of any form whatsoever must retain the following * acknowledgment: * "This product includes software developed by the OpenSSL Project * for use in the OpenSSL Toolkit (http://www.openssl.org/)" * * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED * OF THE POSSIBILITY OF SUCH DAMAGE. * ==================================================================== * * This product includes cryptographic software written by Eric Young * (eay@cryptsoft.com). This product includes software written by Tim * Hudson (tjh@cryptsoft.com). */ #include <openssl_grpc/ssl.h> #include <assert.h> #include <limits.h> #include <stdlib.h> #include <string.h> #include <algorithm> #include <utility> #include <openssl_grpc/aead.h> #include <openssl_grpc/bytestring.h> #include <openssl_grpc/chacha.h> #include <openssl_grpc/curve25519.h> #include <openssl_grpc/digest.h> #include <openssl_grpc/err.h> #include <openssl_grpc/evp.h> #include <openssl_grpc/hmac.h> #include <openssl_grpc/hpke.h> #include <openssl_grpc/mem.h> #include <openssl_grpc/nid.h> #include <openssl_grpc/rand.h> #include "../crypto/internal.h" #include "internal.h" BSSL_NAMESPACE_BEGIN static bool ssl_check_clienthello_tlsext(SSL_HANDSHAKE *hs); static bool ssl_check_serverhello_tlsext(SSL_HANDSHAKE *hs); static int compare_uint16_t(const void *p1, const void *p2) { uint16_t u1 = *((const uint16_t *)p1); uint16_t u2 = *((const uint16_t *)p2); if (u1 < u2) { return -1; } else if (u1 > u2) { return 1; } else { return 0; } } // Per http://tools.ietf.org/html/rfc5246#section-7.4.1.4, there may not be // more than one extension of the same type in a ClientHello or ServerHello. // This function does an initial scan over the extensions block to filter those // out. static bool tls1_check_duplicate_extensions(const CBS *cbs) { // First pass: count the extensions. size_t num_extensions = 0; CBS extensions = *cbs; while (CBS_len(&extensions) > 0) { uint16_t type; CBS extension; if (!CBS_get_u16(&extensions, &type) || !CBS_get_u16_length_prefixed(&extensions, &extension)) { return false; } num_extensions++; } if (num_extensions == 0) { return true; } Array<uint16_t> extension_types; if (!extension_types.Init(num_extensions)) { return false; } // Second pass: gather the extension types. extensions = *cbs; for (size_t i = 0; i < extension_types.size(); i++) { CBS extension; if (!CBS_get_u16(&extensions, &extension_types[i]) || !CBS_get_u16_length_prefixed(&extensions, &extension)) { // This should not happen. return false; } } assert(CBS_len(&extensions) == 0); // Sort the extensions and make sure there are no duplicates. qsort(extension_types.data(), extension_types.size(), sizeof(uint16_t), compare_uint16_t); for (size_t i = 1; i < num_extensions; i++) { if (extension_types[i - 1] == extension_types[i]) { return false; } } return true; } static bool is_post_quantum_group(uint16_t id) { return id == SSL_CURVE_CECPQ2; } bool ssl_client_hello_init(const SSL *ssl, SSL_CLIENT_HELLO *out, Span<const uint8_t> body) { CBS cbs = body; if (!ssl_parse_client_hello_with_trailing_data(ssl, &cbs, out) || CBS_len(&cbs) != 0) { return false; } return true; } bool ssl_parse_client_hello_with_trailing_data(const SSL *ssl, CBS *cbs, SSL_CLIENT_HELLO *out) { OPENSSL_memset(out, 0, sizeof(*out)); out->ssl = const_cast<SSL *>(ssl); CBS copy = *cbs; CBS random, session_id; if (!CBS_get_u16(cbs, &out->version) || !CBS_get_bytes(cbs, &random, SSL3_RANDOM_SIZE) || !CBS_get_u8_length_prefixed(cbs, &session_id) || CBS_len(&session_id) > SSL_MAX_SSL_SESSION_ID_LENGTH) { return false; } out->random = CBS_data(&random); out->random_len = CBS_len(&random); out->session_id = CBS_data(&session_id); out->session_id_len = CBS_len(&session_id); // Skip past DTLS cookie if (SSL_is_dtls(out->ssl)) { CBS cookie; if (!CBS_get_u8_length_prefixed(cbs, &cookie) || CBS_len(&cookie) > DTLS1_COOKIE_LENGTH) { return false; } } CBS cipher_suites, compression_methods; if (!CBS_get_u16_length_prefixed(cbs, &cipher_suites) || CBS_len(&cipher_suites) < 2 || (CBS_len(&cipher_suites) & 1) != 0 || !CBS_get_u8_length_prefixed(cbs, &compression_methods) || CBS_len(&compression_methods) < 1) { return false; } out->cipher_suites = CBS_data(&cipher_suites); out->cipher_suites_len = CBS_len(&cipher_suites); out->compression_methods = CBS_data(&compression_methods); out->compression_methods_len = CBS_len(&compression_methods); // If the ClientHello ends here then it's valid, but doesn't have any // extensions. if (CBS_len(cbs) == 0) { out->extensions = nullptr; out->extensions_len = 0; } else { // Extract extensions and check it is valid. CBS extensions; if (!CBS_get_u16_length_prefixed(cbs, &extensions) || !tls1_check_duplicate_extensions(&extensions)) { return false; } out->extensions = CBS_data(&extensions); out->extensions_len = CBS_len(&extensions); } out->client_hello = CBS_data(©); out->client_hello_len = CBS_len(©) - CBS_len(cbs); return true; } bool ssl_client_hello_get_extension(const SSL_CLIENT_HELLO *client_hello, CBS *out, uint16_t extension_type) { CBS extensions; CBS_init(&extensions, client_hello->extensions, client_hello->extensions_len); while (CBS_len(&extensions) != 0) { // Decode the next extension. uint16_t type; CBS extension; if (!CBS_get_u16(&extensions, &type) || !CBS_get_u16_length_prefixed(&extensions, &extension)) { return false; } if (type == extension_type) { *out = extension; return true; } } return false; } static const uint16_t kDefaultGroups[] = { SSL_CURVE_X25519, SSL_CURVE_SECP256R1, SSL_CURVE_SECP384R1, }; Span<const uint16_t> tls1_get_grouplist(const SSL_HANDSHAKE *hs) { if (!hs->config->supported_group_list.empty()) { return hs->config->supported_group_list; } return Span<const uint16_t>(kDefaultGroups); } bool tls1_get_shared_group(SSL_HANDSHAKE *hs, uint16_t *out_group_id) { SSL *const ssl = hs->ssl; assert(ssl->server); // Clients are not required to send a supported_groups extension. In this // case, the server is free to pick any group it likes. See RFC 4492, // section 4, paragraph 3. // // However, in the interests of compatibility, we will skip ECDH if the // client didn't send an extension because we can't be sure that they'll // support our favoured group. Thus we do not special-case an emtpy // |peer_supported_group_list|. Span<const uint16_t> groups = tls1_get_grouplist(hs); Span<const uint16_t> pref, supp; if (ssl->options & SSL_OP_CIPHER_SERVER_PREFERENCE) { pref = groups; supp = hs->peer_supported_group_list; } else { pref = hs->peer_supported_group_list; supp = groups; } for (uint16_t pref_group : pref) { for (uint16_t supp_group : supp) { if (pref_group == supp_group && // CECPQ2(b) doesn't fit in the u8-length-prefixed ECPoint field in // TLS 1.2 and below. (ssl_protocol_version(ssl) >= TLS1_3_VERSION || !is_post_quantum_group(pref_group))) { *out_group_id = pref_group; return true; } } } return false; } bool tls1_set_curves(Array<uint16_t> *out_group_ids, Span<const int> curves) { Array<uint16_t> group_ids; if (!group_ids.Init(curves.size())) { return false; } for (size_t i = 0; i < curves.size(); i++) { if (!ssl_nid_to_group_id(&group_ids[i], curves[i])) { return false; } } *out_group_ids = std::move(group_ids); return true; } bool tls1_set_curves_list(Array<uint16_t> *out_group_ids, const char *curves) { // Count the number of curves in the list. size_t count = 0; const char *ptr = curves, *col; do { col = strchr(ptr, ':'); count++; if (col) { ptr = col + 1; } } while (col); Array<uint16_t> group_ids; if (!group_ids.Init(count)) { return false; } size_t i = 0; ptr = curves; do { col = strchr(ptr, ':'); if (!ssl_name_to_group_id(&group_ids[i++], ptr, col ? (size_t)(col - ptr) : strlen(ptr))) { return false; } if (col) { ptr = col + 1; } } while (col); assert(i == count); *out_group_ids = std::move(group_ids); return true; } bool tls1_check_group_id(const SSL_HANDSHAKE *hs, uint16_t group_id) { if (is_post_quantum_group(group_id) && ssl_protocol_version(hs->ssl) < TLS1_3_VERSION) { // CECPQ2(b) requires TLS 1.3. return false; } // We internally assume zero is never allocated as a group ID. if (group_id == 0) { return false; } for (uint16_t supported : tls1_get_grouplist(hs)) { if (supported == group_id) { return true; } } return false; } // kVerifySignatureAlgorithms is the default list of accepted signature // algorithms for verifying. static const uint16_t kVerifySignatureAlgorithms[] = { // List our preferred algorithms first. SSL_SIGN_ECDSA_SECP256R1_SHA256, SSL_SIGN_RSA_PSS_RSAE_SHA256, SSL_SIGN_RSA_PKCS1_SHA256, // Larger hashes are acceptable. SSL_SIGN_ECDSA_SECP384R1_SHA384, SSL_SIGN_RSA_PSS_RSAE_SHA384, SSL_SIGN_RSA_PKCS1_SHA384, SSL_SIGN_RSA_PSS_RSAE_SHA512, SSL_SIGN_RSA_PKCS1_SHA512, // For now, SHA-1 is still accepted but least preferable. SSL_SIGN_RSA_PKCS1_SHA1, }; // kSignSignatureAlgorithms is the default list of supported signature // algorithms for signing. static const uint16_t kSignSignatureAlgorithms[] = { // List our preferred algorithms first. SSL_SIGN_ED25519, SSL_SIGN_ECDSA_SECP256R1_SHA256, SSL_SIGN_RSA_PSS_RSAE_SHA256, SSL_SIGN_RSA_PKCS1_SHA256, // If needed, sign larger hashes. // // TODO(davidben): Determine which of these may be pruned. SSL_SIGN_ECDSA_SECP384R1_SHA384, SSL_SIGN_RSA_PSS_RSAE_SHA384, SSL_SIGN_RSA_PKCS1_SHA384, SSL_SIGN_ECDSA_SECP521R1_SHA512, SSL_SIGN_RSA_PSS_RSAE_SHA512, SSL_SIGN_RSA_PKCS1_SHA512, // If the peer supports nothing else, sign with SHA-1. SSL_SIGN_ECDSA_SHA1, SSL_SIGN_RSA_PKCS1_SHA1, }; static Span<const uint16_t> tls12_get_verify_sigalgs(const SSL_HANDSHAKE *hs) { if (hs->config->verify_sigalgs.empty()) { return Span<const uint16_t>(kVerifySignatureAlgorithms); } return hs->config->verify_sigalgs; } bool tls12_add_verify_sigalgs(const SSL_HANDSHAKE *hs, CBB *out) { for (uint16_t sigalg : tls12_get_verify_sigalgs(hs)) { if (!CBB_add_u16(out, sigalg)) { return false; } } return true; } bool tls12_check_peer_sigalg(const SSL_HANDSHAKE *hs, uint8_t *out_alert, uint16_t sigalg) { for (uint16_t verify_sigalg : tls12_get_verify_sigalgs(hs)) { if (verify_sigalg == sigalg) { return true; } } OPENSSL_PUT_ERROR(SSL, SSL_R_WRONG_SIGNATURE_TYPE); *out_alert = SSL_AD_ILLEGAL_PARAMETER; return false; } // tls_extension represents a TLS extension that is handled internally. // // The parse callbacks receive a |CBS| that contains the contents of the // extension (i.e. not including the type and length bytes). If an extension is // not received then the parse callbacks will be called with a NULL CBS so that // they can do any processing needed to handle the absence of an extension. // // The add callbacks receive a |CBB| to which the extension can be appended but // the function is responsible for appending the type and length bytes too. // // |add_clienthello| may be called multiple times and must not mutate |hs|. It // is additionally passed two output |CBB|s. If the extension is the same // independent of the value of |type|, the callback may write to // |out_compressible| instead of |out|. When serializing the ClientHelloInner, // all compressible extensions will be made continguous and replaced with // ech_outer_extensions when encrypted. When serializing the ClientHelloOuter // or not offering ECH, |out| will be equal to |out_compressible|, so writing to // |out_compressible| still works. // // Note the |parse_serverhello| and |add_serverhello| callbacks refer to the // TLS 1.2 ServerHello. In TLS 1.3, these callbacks act on EncryptedExtensions, // with ServerHello extensions handled elsewhere in the handshake. // // All callbacks return true for success and false for error. If a parse // function returns zero then a fatal alert with value |*out_alert| will be // sent. If |*out_alert| isn't set, then a |decode_error| alert will be sent. struct tls_extension { uint16_t value; bool (*add_clienthello)(const SSL_HANDSHAKE *hs, CBB *out, CBB *out_compressible, ssl_client_hello_type_t type); bool (*parse_serverhello)(SSL_HANDSHAKE *hs, uint8_t *out_alert, CBS *contents); bool (*parse_clienthello)(SSL_HANDSHAKE *hs, uint8_t *out_alert, CBS *contents); bool (*add_serverhello)(SSL_HANDSHAKE *hs, CBB *out); }; static bool forbid_parse_serverhello(SSL_HANDSHAKE *hs, uint8_t *out_alert, CBS *contents) { if (contents != NULL) { // Servers MUST NOT send this extension. *out_alert = SSL_AD_UNSUPPORTED_EXTENSION; OPENSSL_PUT_ERROR(SSL, SSL_R_UNEXPECTED_EXTENSION); return false; } return true; } static bool ignore_parse_clienthello(SSL_HANDSHAKE *hs, uint8_t *out_alert, CBS *contents) { // This extension from the client is handled elsewhere. return true; } static bool dont_add_serverhello(SSL_HANDSHAKE *hs, CBB *out) { return true; } // Server name indication (SNI). // // https://tools.ietf.org/html/rfc6066#section-3. static bool ext_sni_add_clienthello(const SSL_HANDSHAKE *hs, CBB *out, CBB *out_compressible, ssl_client_hello_type_t type) { const SSL *const ssl = hs->ssl; // If offering ECH, send the public name instead of the configured name. Span<const uint8_t> hostname; if (type == ssl_client_hello_outer) { hostname = hs->selected_ech_config->public_name; } else { if (ssl->hostname == nullptr) { return true; } hostname = MakeConstSpan(reinterpret_cast<const uint8_t *>(ssl->hostname.get()), strlen(ssl->hostname.get())); } CBB contents, server_name_list, name; if (!CBB_add_u16(out, TLSEXT_TYPE_server_name) || !CBB_add_u16_length_prefixed(out, &contents) || !CBB_add_u16_length_prefixed(&contents, &server_name_list) || !CBB_add_u8(&server_name_list, TLSEXT_NAMETYPE_host_name) || !CBB_add_u16_length_prefixed(&server_name_list, &name) || !CBB_add_bytes(&name, hostname.data(), hostname.size()) || !CBB_flush(out)) { return false; } return true; } static bool ext_sni_parse_serverhello(SSL_HANDSHAKE *hs, uint8_t *out_alert, CBS *contents) { // The server may acknowledge SNI with an empty extension. We check the syntax // but otherwise ignore this signal. return contents == NULL || CBS_len(contents) == 0; } static bool ext_sni_parse_clienthello(SSL_HANDSHAKE *hs, uint8_t *out_alert, CBS *contents) { // SNI has already been parsed earlier in the handshake. See |extract_sni|. return true; } static bool ext_sni_add_serverhello(SSL_HANDSHAKE *hs, CBB *out) { if (hs->ssl->s3->session_reused || !hs->should_ack_sni) { return true; } if (!CBB_add_u16(out, TLSEXT_TYPE_server_name) || !CBB_add_u16(out, 0 /* length */)) { return false; } return true; } // Encrypted ClientHello (ECH) // // https://tools.ietf.org/html/draft-ietf-tls-esni-13 static bool ext_ech_add_clienthello(const SSL_HANDSHAKE *hs, CBB *out, CBB *out_compressible, ssl_client_hello_type_t type) { if (type == ssl_client_hello_inner) { if (!CBB_add_u16(out, TLSEXT_TYPE_encrypted_client_hello) || !CBB_add_u16(out, /* length */ 1) || !CBB_add_u8(out, ECH_CLIENT_INNER)) { return false; } return true; } if (hs->ech_client_outer.empty()) { return true; } CBB ech_body; if (!CBB_add_u16(out, TLSEXT_TYPE_encrypted_client_hello) || !CBB_add_u16_length_prefixed(out, &ech_body) || !CBB_add_u8(&ech_body, ECH_CLIENT_OUTER) || !CBB_add_bytes(&ech_body, hs->ech_client_outer.data(), hs->ech_client_outer.size()) || !CBB_flush(out)) { return false; } return true; } static bool ext_ech_parse_serverhello(SSL_HANDSHAKE *hs, uint8_t *out_alert, CBS *contents) { SSL *const ssl = hs->ssl; if (contents == NULL) { return true; } // The ECH extension may not be sent in TLS 1.2 ServerHello, only TLS 1.3 // EncryptedExtensions. It also may not be sent in response to an inner ECH // extension. if (ssl_protocol_version(ssl) < TLS1_3_VERSION || ssl->s3->ech_status == ssl_ech_accepted) { *out_alert = SSL_AD_UNSUPPORTED_EXTENSION; OPENSSL_PUT_ERROR(SSL, SSL_R_UNEXPECTED_EXTENSION); return false; } if (!ssl_is_valid_ech_config_list(*contents)) { *out_alert = SSL_AD_DECODE_ERROR; return false; } if (ssl->s3->ech_status == ssl_ech_rejected && !hs->ech_retry_configs.CopyFrom(*contents)) { *out_alert = SSL_AD_INTERNAL_ERROR; return false; } return true; } static bool ext_ech_parse_clienthello(SSL_HANDSHAKE *hs, uint8_t *out_alert, CBS *contents) { if (contents == nullptr) { return true; } uint8_t type; if (!CBS_get_u8(contents, &type)) { return false; } if (type == ECH_CLIENT_OUTER) { // Outer ECH extensions are handled outside the callback. return true; } if (type != ECH_CLIENT_INNER || CBS_len(contents) != 0) { return false; } hs->ech_is_inner = true; return true; } static bool ext_ech_add_serverhello(SSL_HANDSHAKE *hs, CBB *out) { SSL *const ssl = hs->ssl; if (ssl_protocol_version(ssl) < TLS1_3_VERSION || ssl->s3->ech_status == ssl_ech_accepted || // hs->ech_keys == nullptr) { return true; } // Write the list of retry configs to |out|. Note |SSL_CTX_set1_ech_keys| // ensures |ech_keys| contains at least one retry config. CBB body, retry_configs; if (!CBB_add_u16(out, TLSEXT_TYPE_encrypted_client_hello) || !CBB_add_u16_length_prefixed(out, &body) || !CBB_add_u16_length_prefixed(&body, &retry_configs)) { return false; } for (const auto &config : hs->ech_keys->configs) { if (!config->is_retry_config()) { continue; } if (!CBB_add_bytes(&retry_configs, config->ech_config().raw.data(), config->ech_config().raw.size())) { return false; } } return CBB_flush(out); } // Renegotiation indication. // // https://tools.ietf.org/html/rfc5746 static bool ext_ri_add_clienthello(const SSL_HANDSHAKE *hs, CBB *out, CBB *out_compressible, ssl_client_hello_type_t type) { const SSL *const ssl = hs->ssl; // Renegotiation indication is not necessary in TLS 1.3. if (hs->min_version >= TLS1_3_VERSION || type == ssl_client_hello_inner) { return true; } assert(ssl->s3->initial_handshake_complete == (ssl->s3->previous_client_finished_len != 0)); CBB contents, prev_finished; if (!CBB_add_u16(out, TLSEXT_TYPE_renegotiate) || !CBB_add_u16_length_prefixed(out, &contents) || !CBB_add_u8_length_prefixed(&contents, &prev_finished) || !CBB_add_bytes(&prev_finished, ssl->s3->previous_client_finished, ssl->s3->previous_client_finished_len) || !CBB_flush(out)) { return false; } return true; } static bool ext_ri_parse_serverhello(SSL_HANDSHAKE *hs, uint8_t *out_alert, CBS *contents) { SSL *const ssl = hs->ssl; if (contents != NULL && ssl_protocol_version(ssl) >= TLS1_3_VERSION) { *out_alert = SSL_AD_ILLEGAL_PARAMETER; return false; } // Servers may not switch between omitting the extension and supporting it. // See RFC 5746, sections 3.5 and 4.2. if (ssl->s3->initial_handshake_complete && (contents != NULL) != ssl->s3->send_connection_binding) { *out_alert = SSL_AD_HANDSHAKE_FAILURE; OPENSSL_PUT_ERROR(SSL, SSL_R_RENEGOTIATION_MISMATCH); return false; } if (contents == NULL) { // Strictly speaking, if we want to avoid an attack we should *always* see // RI even on initial ServerHello because the client doesn't see any // renegotiation during an attack. However this would mean we could not // connect to any server which doesn't support RI. // // OpenSSL has |SSL_OP_LEGACY_SERVER_CONNECT| to control this, but in // practical terms every client sets it so it's just assumed here. return true; } const size_t expected_len = ssl->s3->previous_client_finished_len + ssl->s3->previous_server_finished_len; // Check for logic errors assert(!expected_len || ssl->s3->previous_client_finished_len); assert(!expected_len || ssl->s3->previous_server_finished_len); assert(ssl->s3->initial_handshake_complete == (ssl->s3->previous_client_finished_len != 0)); assert(ssl->s3->initial_handshake_complete == (ssl->s3->previous_server_finished_len != 0)); // Parse out the extension contents. CBS renegotiated_connection; if (!CBS_get_u8_length_prefixed(contents, &renegotiated_connection) || CBS_len(contents) != 0) { OPENSSL_PUT_ERROR(SSL, SSL_R_RENEGOTIATION_ENCODING_ERR); *out_alert = SSL_AD_ILLEGAL_PARAMETER; return false; } // Check that the extension matches. if (CBS_len(&renegotiated_connection) != expected_len) { OPENSSL_PUT_ERROR(SSL, SSL_R_RENEGOTIATION_MISMATCH); *out_alert = SSL_AD_HANDSHAKE_FAILURE; return false; } const uint8_t *d = CBS_data(&renegotiated_connection); bool ok = CRYPTO_memcmp(d, ssl->s3->previous_client_finished, ssl->s3->previous_client_finished_len) == 0; #if defined(BORINGSSL_UNSAFE_FUZZER_MODE) ok = true; #endif if (!ok) { OPENSSL_PUT_ERROR(SSL, SSL_R_RENEGOTIATION_MISMATCH); *out_alert = SSL_AD_HANDSHAKE_FAILURE; return false; } d += ssl->s3->previous_client_finished_len; ok = CRYPTO_memcmp(d, ssl->s3->previous_server_finished, ssl->s3->previous_server_finished_len) == 0; #if defined(BORINGSSL_UNSAFE_FUZZER_MODE) ok = true; #endif if (!ok) { OPENSSL_PUT_ERROR(SSL, SSL_R_RENEGOTIATION_MISMATCH); *out_alert = SSL_AD_HANDSHAKE_FAILURE; return false; } ssl->s3->send_connection_binding = true; return true; } static bool ext_ri_parse_clienthello(SSL_HANDSHAKE *hs, uint8_t *out_alert, CBS *contents) { SSL *const ssl = hs->ssl; // Renegotiation isn't supported as a server so this function should never be // called after the initial handshake. assert(!ssl->s3->initial_handshake_complete); if (ssl_protocol_version(ssl) >= TLS1_3_VERSION) { return true; } if (contents == NULL) { return true; } CBS renegotiated_connection; if (!CBS_get_u8_length_prefixed(contents, &renegotiated_connection) || CBS_len(contents) != 0) { OPENSSL_PUT_ERROR(SSL, SSL_R_RENEGOTIATION_ENCODING_ERR); return false; } // Check that the extension matches. We do not support renegotiation as a // server, so this must be empty. if (CBS_len(&renegotiated_connection) != 0) { OPENSSL_PUT_ERROR(SSL, SSL_R_RENEGOTIATION_MISMATCH); *out_alert = SSL_AD_HANDSHAKE_FAILURE; return false; } ssl->s3->send_connection_binding = true; return true; } static bool ext_ri_add_serverhello(SSL_HANDSHAKE *hs, CBB *out) { SSL *const ssl = hs->ssl; // Renegotiation isn't supported as a server so this function should never be // called after the initial handshake. assert(!ssl->s3->initial_handshake_complete); if (ssl_protocol_version(ssl) >= TLS1_3_VERSION) { return true; } if (!CBB_add_u16(out, TLSEXT_TYPE_renegotiate) || !CBB_add_u16(out, 1 /* length */) || !CBB_add_u8(out, 0 /* empty renegotiation info */)) { return false; } return true; } // Extended Master Secret. // // https://tools.ietf.org/html/rfc7627 static bool ext_ems_add_clienthello(const SSL_HANDSHAKE *hs, CBB *out, CBB *out_compressible, ssl_client_hello_type_t type) { // Extended master secret is not necessary in TLS 1.3. if (hs->min_version >= TLS1_3_VERSION || type == ssl_client_hello_inner) { return true; } if (!CBB_add_u16(out, TLSEXT_TYPE_extended_master_secret) || !CBB_add_u16(out, 0 /* length */)) { return false; } return true; } static bool ext_ems_parse_serverhello(SSL_HANDSHAKE *hs, uint8_t *out_alert, CBS *contents) { SSL *const ssl = hs->ssl; if (contents != NULL) { if (ssl_protocol_version(ssl) >= TLS1_3_VERSION || CBS_len(contents) != 0) { return false; } hs->extended_master_secret = true; } // Whether EMS is negotiated may not change on renegotiation. if (ssl->s3->established_session != nullptr && hs->extended_master_secret != !!ssl->s3->established_session->extended_master_secret) { OPENSSL_PUT_ERROR(SSL, SSL_R_RENEGOTIATION_EMS_MISMATCH); *out_alert = SSL_AD_ILLEGAL_PARAMETER; return false; } return true; } static bool ext_ems_parse_clienthello(SSL_HANDSHAKE *hs, uint8_t *out_alert, CBS *contents) { if (ssl_protocol_version(hs->ssl) >= TLS1_3_VERSION) { return true; } if (contents == NULL) { return true; } if (CBS_len(contents) != 0) { return false; } hs->extended_master_secret = true; return true; } static bool ext_ems_add_serverhello(SSL_HANDSHAKE *hs, CBB *out) { if (!hs->extended_master_secret) { return true; } if (!CBB_add_u16(out, TLSEXT_TYPE_extended_master_secret) || !CBB_add_u16(out, 0 /* length */)) { return false; } return true; } // Session tickets. // // https://tools.ietf.org/html/rfc5077 static bool ext_ticket_add_clienthello(const SSL_HANDSHAKE *hs, CBB *out, CBB *out_compressible, ssl_client_hello_type_t type) { const SSL *const ssl = hs->ssl; // TLS 1.3 uses a different ticket extension. if (hs->min_version >= TLS1_3_VERSION || type == ssl_client_hello_inner || SSL_get_options(ssl) & SSL_OP_NO_TICKET) { return true; } Span<const uint8_t> ticket; // Renegotiation does not participate in session resumption. However, still // advertise the extension to avoid potentially breaking servers which carry // over the state from the previous handshake, such as OpenSSL servers // without upstream's 3c3f0259238594d77264a78944d409f2127642c4. if (!ssl->s3->initial_handshake_complete && ssl->session != nullptr && !ssl->session->ticket.empty() && // Don't send TLS 1.3 session tickets in the ticket extension. ssl_session_protocol_version(ssl->session.get()) < TLS1_3_VERSION) { ticket = ssl->session->ticket; } CBB ticket_cbb; if (!CBB_add_u16(out, TLSEXT_TYPE_session_ticket) || !CBB_add_u16_length_prefixed(out, &ticket_cbb) || !CBB_add_bytes(&ticket_cbb, ticket.data(), ticket.size()) || !CBB_flush(out)) { return false; } return true; } static bool ext_ticket_parse_serverhello(SSL_HANDSHAKE *hs, uint8_t *out_alert, CBS *contents) { SSL *const ssl = hs->ssl; if (contents == NULL) { return true; } if (ssl_protocol_version(ssl) >= TLS1_3_VERSION) { return false; } // If |SSL_OP_NO_TICKET| is set then no extension will have been sent and // this function should never be called, even if the server tries to send the // extension. assert((SSL_get_options(ssl) & SSL_OP_NO_TICKET) == 0); if (CBS_len(contents) != 0) { return false; } hs->ticket_expected = true; return true; } static bool ext_ticket_add_serverhello(SSL_HANDSHAKE *hs, CBB *out) { if (!hs->ticket_expected) { return true; } // If |SSL_OP_NO_TICKET| is set, |ticket_expected| should never be true. assert((SSL_get_options(hs->ssl) & SSL_OP_NO_TICKET) == 0); if (!CBB_add_u16(out, TLSEXT_TYPE_session_ticket) || !CBB_add_u16(out, 0 /* length */)) { return false; } return true; } // Signature Algorithms. // // https://tools.ietf.org/html/rfc5246#section-7.4.1.4.1 static bool ext_sigalgs_add_clienthello(const SSL_HANDSHAKE *hs, CBB *out, CBB *out_compressible, ssl_client_hello_type_t type) { if (hs->max_version < TLS1_2_VERSION) { return true; } CBB contents, sigalgs_cbb; if (!CBB_add_u16(out_compressible, TLSEXT_TYPE_signature_algorithms) || !CBB_add_u16_length_prefixed(out_compressible, &contents) || !CBB_add_u16_length_prefixed(&contents, &sigalgs_cbb) || !tls12_add_verify_sigalgs(hs, &sigalgs_cbb) || !CBB_flush(out_compressible)) { return false; } return true; } static bool ext_sigalgs_parse_clienthello(SSL_HANDSHAKE *hs, uint8_t *out_alert, CBS *contents) { hs->peer_sigalgs.Reset(); if (contents == NULL) { return true; } CBS supported_signature_algorithms; if (!CBS_get_u16_length_prefixed(contents, &supported_signature_algorithms) || CBS_len(contents) != 0 || !tls1_parse_peer_sigalgs(hs, &supported_signature_algorithms)) { return false; } return true; } // OCSP Stapling. // // https://tools.ietf.org/html/rfc6066#section-8 static bool ext_ocsp_add_clienthello(const SSL_HANDSHAKE *hs, CBB *out, CBB *out_compressible, ssl_client_hello_type_t type) { if (!hs->config->ocsp_stapling_enabled) { return true; } CBB contents; if (!CBB_add_u16(out_compressible, TLSEXT_TYPE_status_request) || !CBB_add_u16_length_prefixed(out_compressible, &contents) || !CBB_add_u8(&contents, TLSEXT_STATUSTYPE_ocsp) || !CBB_add_u16(&contents, 0 /* empty responder ID list */) || !CBB_add_u16(&contents, 0 /* empty request extensions */) || !CBB_flush(out_compressible)) { return false; } return true; } static bool ext_ocsp_parse_serverhello(SSL_HANDSHAKE *hs, uint8_t *out_alert, CBS *contents) { SSL *const ssl = hs->ssl; if (contents == NULL) { return true; } // TLS 1.3 OCSP responses are included in the Certificate extensions. if (ssl_protocol_version(ssl) >= TLS1_3_VERSION) { return false; } // OCSP stapling is forbidden on non-certificate ciphers. if (CBS_len(contents) != 0 || !ssl_cipher_uses_certificate_auth(hs->new_cipher)) { return false; } // Note this does not check for resumption in TLS 1.2. Sending // status_request here does not make sense, but OpenSSL does so and the // specification does not say anything. Tolerate it but ignore it. hs->certificate_status_expected = true; return true; } static bool ext_ocsp_parse_clienthello(SSL_HANDSHAKE *hs, uint8_t *out_alert, CBS *contents) { if (contents == NULL) { return true; } uint8_t status_type; if (!CBS_get_u8(contents, &status_type)) { return false; } // We cannot decide whether OCSP stapling will occur yet because the correct // SSL_CTX might not have been selected. hs->ocsp_stapling_requested = status_type == TLSEXT_STATUSTYPE_ocsp; return true; } static bool ext_ocsp_add_serverhello(SSL_HANDSHAKE *hs, CBB *out) { SSL *const ssl = hs->ssl; if (ssl_protocol_version(ssl) >= TLS1_3_VERSION || !hs->ocsp_stapling_requested || hs->config->cert->ocsp_response == NULL || ssl->s3->session_reused || !ssl_cipher_uses_certificate_auth(hs->new_cipher)) { return true; } hs->certificate_status_expected = true; return CBB_add_u16(out, TLSEXT_TYPE_status_request) && CBB_add_u16(out, 0 /* length */); } // Next protocol negotiation. // // https://htmlpreview.github.io/?https://github.com/agl/technotes/blob/master/nextprotoneg.html static bool ext_npn_add_clienthello(const SSL_HANDSHAKE *hs, CBB *out, CBB *out_compressible, ssl_client_hello_type_t type) { const SSL *const ssl = hs->ssl; if (ssl->ctx->next_proto_select_cb == NULL || // Do not allow NPN to change on renegotiation. ssl->s3->initial_handshake_complete || // NPN is not defined in DTLS or TLS 1.3. SSL_is_dtls(ssl) || hs->min_version >= TLS1_3_VERSION || type == ssl_client_hello_inner) { return true; } if (!CBB_add_u16(out, TLSEXT_TYPE_next_proto_neg) || !CBB_add_u16(out, 0 /* length */)) { return false; } return true; } static bool ext_npn_parse_serverhello(SSL_HANDSHAKE *hs, uint8_t *out_alert, CBS *contents) { SSL *const ssl = hs->ssl; if (contents == NULL) { return true; } if (ssl_protocol_version(ssl) >= TLS1_3_VERSION) { return false; } // If any of these are false then we should never have sent the NPN // extension in the ClientHello and thus this function should never have been // called. assert(!ssl->s3->initial_handshake_complete); assert(!SSL_is_dtls(ssl)); assert(ssl->ctx->next_proto_select_cb != NULL); if (!ssl->s3->alpn_selected.empty()) { // NPN and ALPN may not be negotiated in the same connection. *out_alert = SSL_AD_ILLEGAL_PARAMETER; OPENSSL_PUT_ERROR(SSL, SSL_R_NEGOTIATED_BOTH_NPN_AND_ALPN); return false; } const uint8_t *const orig_contents = CBS_data(contents); const size_t orig_len = CBS_len(contents); while (CBS_len(contents) != 0) { CBS proto; if (!CBS_get_u8_length_prefixed(contents, &proto) || CBS_len(&proto) == 0) { return false; } } uint8_t *selected; uint8_t selected_len; if (ssl->ctx->next_proto_select_cb( ssl, &selected, &selected_len, orig_contents, orig_len, ssl->ctx->next_proto_select_cb_arg) != SSL_TLSEXT_ERR_OK || !ssl->s3->next_proto_negotiated.CopyFrom( MakeConstSpan(selected, selected_len))) { *out_alert = SSL_AD_INTERNAL_ERROR; return false; } hs->next_proto_neg_seen = true; return true; } static bool ext_npn_parse_clienthello(SSL_HANDSHAKE *hs, uint8_t *out_alert, CBS *contents) { SSL *const ssl = hs->ssl; if (ssl_protocol_version(ssl) >= TLS1_3_VERSION) { return true; } if (contents != NULL && CBS_len(contents) != 0) { return false; } if (contents == NULL || ssl->s3->initial_handshake_complete || ssl->ctx->next_protos_advertised_cb == NULL || SSL_is_dtls(ssl)) { return true; } hs->next_proto_neg_seen = true; return true; } static bool ext_npn_add_serverhello(SSL_HANDSHAKE *hs, CBB *out) { SSL *const ssl = hs->ssl; // |next_proto_neg_seen| might have been cleared when an ALPN extension was // parsed. if (!hs->next_proto_neg_seen) { return true; } const uint8_t *npa; unsigned npa_len; if (ssl->ctx->next_protos_advertised_cb( ssl, &npa, &npa_len, ssl->ctx->next_protos_advertised_cb_arg) != SSL_TLSEXT_ERR_OK) { hs->next_proto_neg_seen = false; return true; } CBB contents; if (!CBB_add_u16(out, TLSEXT_TYPE_next_proto_neg) || !CBB_add_u16_length_prefixed(out, &contents) || !CBB_add_bytes(&contents, npa, npa_len) || !CBB_flush(out)) { return false; } return true; } // Signed certificate timestamps. // // https://tools.ietf.org/html/rfc6962#section-3.3.1 static bool ext_sct_add_clienthello(const SSL_HANDSHAKE *hs, CBB *out, CBB *out_compressible, ssl_client_hello_type_t type) { if (!hs->config->signed_cert_timestamps_enabled) { return true; } if (!CBB_add_u16(out_compressible, TLSEXT_TYPE_certificate_timestamp) || !CBB_add_u16(out_compressible, 0 /* length */)) { return false; } return true; } static bool ext_sct_parse_serverhello(SSL_HANDSHAKE *hs, uint8_t *out_alert, CBS *contents) { SSL *const ssl = hs->ssl; if (contents == NULL) { return true; } // TLS 1.3 SCTs are included in the Certificate extensions. if (ssl_protocol_version(ssl) >= TLS1_3_VERSION) { *out_alert = SSL_AD_DECODE_ERROR; return false; } // If this is false then we should never have sent the SCT extension in the // ClientHello and thus this function should never have been called. assert(hs->config->signed_cert_timestamps_enabled); if (!ssl_is_sct_list_valid(contents)) { *out_alert = SSL_AD_DECODE_ERROR; return false; } // Session resumption uses the original session information. The extension // should not be sent on resumption, but RFC 6962 did not make it a // requirement, so tolerate this. // // TODO(davidben): Enforce this anyway. if (!ssl->s3->session_reused) { hs->new_session->signed_cert_timestamp_list.reset( CRYPTO_BUFFER_new_from_CBS(contents, ssl->ctx->pool)); if (hs->new_session->signed_cert_timestamp_list == nullptr) { *out_alert = SSL_AD_INTERNAL_ERROR; return false; } } return true; } static bool ext_sct_parse_clienthello(SSL_HANDSHAKE *hs, uint8_t *out_alert, CBS *contents) { if (contents == NULL) { return true; } if (CBS_len(contents) != 0) { return false; } hs->scts_requested = true; return true; } static bool ext_sct_add_serverhello(SSL_HANDSHAKE *hs, CBB *out) { SSL *const ssl = hs->ssl; // The extension shouldn't be sent when resuming sessions. if (ssl_protocol_version(ssl) >= TLS1_3_VERSION || ssl->s3->session_reused || hs->config->cert->signed_cert_timestamp_list == NULL) { return true; } CBB contents; return CBB_add_u16(out, TLSEXT_TYPE_certificate_timestamp) && CBB_add_u16_length_prefixed(out, &contents) && CBB_add_bytes( &contents, CRYPTO_BUFFER_data( hs->config->cert->signed_cert_timestamp_list.get()), CRYPTO_BUFFER_len( hs->config->cert->signed_cert_timestamp_list.get())) && CBB_flush(out); } // Application-level Protocol Negotiation. // // https://tools.ietf.org/html/rfc7301 static bool ext_alpn_add_clienthello(const SSL_HANDSHAKE *hs, CBB *out, CBB *out_compressible, ssl_client_hello_type_t type) { const SSL *const ssl = hs->ssl; if (hs->config->alpn_client_proto_list.empty() && ssl->quic_method) { // ALPN MUST be used with QUIC. OPENSSL_PUT_ERROR(SSL, SSL_R_NO_APPLICATION_PROTOCOL); return false; } if (hs->config->alpn_client_proto_list.empty() || ssl->s3->initial_handshake_complete) { return true; } CBB contents, proto_list; if (!CBB_add_u16(out_compressible, TLSEXT_TYPE_application_layer_protocol_negotiation) || !CBB_add_u16_length_prefixed(out_compressible, &contents) || !CBB_add_u16_length_prefixed(&contents, &proto_list) || !CBB_add_bytes(&proto_list, hs->config->alpn_client_proto_list.data(), hs->config->alpn_client_proto_list.size()) || !CBB_flush(out_compressible)) { return false; } return true; } static bool ext_alpn_parse_serverhello(SSL_HANDSHAKE *hs, uint8_t *out_alert, CBS *contents) { SSL *const ssl = hs->ssl; if (contents == NULL) { if (ssl->quic_method) { // ALPN is required when QUIC is used. OPENSSL_PUT_ERROR(SSL, SSL_R_NO_APPLICATION_PROTOCOL); *out_alert = SSL_AD_NO_APPLICATION_PROTOCOL; return false; } return true; } assert(!ssl->s3->initial_handshake_complete); assert(!hs->config->alpn_client_proto_list.empty()); if (hs->next_proto_neg_seen) { // NPN and ALPN may not be negotiated in the same connection. *out_alert = SSL_AD_ILLEGAL_PARAMETER; OPENSSL_PUT_ERROR(SSL, SSL_R_NEGOTIATED_BOTH_NPN_AND_ALPN); return false; } // The extension data consists of a ProtocolNameList which must have // exactly one ProtocolName. Each of these is length-prefixed. CBS protocol_name_list, protocol_name; if (!CBS_get_u16_length_prefixed(contents, &protocol_name_list) || CBS_len(contents) != 0 || !CBS_get_u8_length_prefixed(&protocol_name_list, &protocol_name) || // Empty protocol names are forbidden. CBS_len(&protocol_name) == 0 || CBS_len(&protocol_name_list) != 0) { return false; } if (!ssl_is_alpn_protocol_allowed(hs, protocol_name)) { OPENSSL_PUT_ERROR(SSL, SSL_R_INVALID_ALPN_PROTOCOL); *out_alert = SSL_AD_ILLEGAL_PARAMETER; return false; } if (!ssl->s3->alpn_selected.CopyFrom(protocol_name)) { *out_alert = SSL_AD_INTERNAL_ERROR; return false; } return true; } bool ssl_is_valid_alpn_list(Span<const uint8_t> in) { CBS protocol_name_list = in; if (CBS_len(&protocol_name_list) == 0) { return false; } while (CBS_len(&protocol_name_list) > 0) { CBS protocol_name; if (!CBS_get_u8_length_prefixed(&protocol_name_list, &protocol_name) || // Empty protocol names are forbidden. CBS_len(&protocol_name) == 0) { return false; } } return true; } bool ssl_is_alpn_protocol_allowed(const SSL_HANDSHAKE *hs, Span<const uint8_t> protocol) { if (hs->config->alpn_client_proto_list.empty()) { return false; } if (hs->ssl->ctx->allow_unknown_alpn_protos) { return true; } // Check that the protocol name is one of the ones we advertised. CBS client_protocol_name_list = MakeConstSpan(hs->config->alpn_client_proto_list), client_protocol_name; while (CBS_len(&client_protocol_name_list) > 0) { if (!CBS_get_u8_length_prefixed(&client_protocol_name_list, &client_protocol_name)) { return false; } if (client_protocol_name == protocol) { return true; } } return false; } bool ssl_negotiate_alpn(SSL_HANDSHAKE *hs, uint8_t *out_alert, const SSL_CLIENT_HELLO *client_hello) { SSL *const ssl = hs->ssl; CBS contents; if (ssl->ctx->alpn_select_cb == NULL || !ssl_client_hello_get_extension( client_hello, &contents, TLSEXT_TYPE_application_layer_protocol_negotiation)) { if (ssl->quic_method) { // ALPN is required when QUIC is used. OPENSSL_PUT_ERROR(SSL, SSL_R_NO_APPLICATION_PROTOCOL); *out_alert = SSL_AD_NO_APPLICATION_PROTOCOL; return false; } // Ignore ALPN if not configured or no extension was supplied. return true; } // ALPN takes precedence over NPN. hs->next_proto_neg_seen = false; CBS protocol_name_list; if (!CBS_get_u16_length_prefixed(&contents, &protocol_name_list) || CBS_len(&contents) != 0 || !ssl_is_valid_alpn_list(protocol_name_list)) { OPENSSL_PUT_ERROR(SSL, SSL_R_PARSE_TLSEXT); *out_alert = SSL_AD_DECODE_ERROR; return false; } const uint8_t *selected; uint8_t selected_len; int ret = ssl->ctx->alpn_select_cb( ssl, &selected, &selected_len, CBS_data(&protocol_name_list), CBS_len(&protocol_name_list), ssl->ctx->alpn_select_cb_arg); // ALPN is required when QUIC is used. if (ssl->quic_method && (ret == SSL_TLSEXT_ERR_NOACK || ret == SSL_TLSEXT_ERR_ALERT_WARNING)) { ret = SSL_TLSEXT_ERR_ALERT_FATAL; } switch (ret) { case SSL_TLSEXT_ERR_OK: if (selected_len == 0) { OPENSSL_PUT_ERROR(SSL, SSL_R_INVALID_ALPN_PROTOCOL); *out_alert = SSL_AD_INTERNAL_ERROR; return false; } if (!ssl->s3->alpn_selected.CopyFrom( MakeConstSpan(selected, selected_len))) { *out_alert = SSL_AD_INTERNAL_ERROR; return false; } break; case SSL_TLSEXT_ERR_NOACK: case SSL_TLSEXT_ERR_ALERT_WARNING: break; case SSL_TLSEXT_ERR_ALERT_FATAL: *out_alert = SSL_AD_NO_APPLICATION_PROTOCOL; OPENSSL_PUT_ERROR(SSL, SSL_R_NO_APPLICATION_PROTOCOL); return false; default: // Invalid return value. *out_alert = SSL_AD_INTERNAL_ERROR; OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR); return false; } return true; } static bool ext_alpn_add_serverhello(SSL_HANDSHAKE *hs, CBB *out) { SSL *const ssl = hs->ssl; if (ssl->s3->alpn_selected.empty()) { return true; } CBB contents, proto_list, proto; if (!CBB_add_u16(out, TLSEXT_TYPE_application_layer_protocol_negotiation) || !CBB_add_u16_length_prefixed(out, &contents) || !CBB_add_u16_length_prefixed(&contents, &proto_list) || !CBB_add_u8_length_prefixed(&proto_list, &proto) || !CBB_add_bytes(&proto, ssl->s3->alpn_selected.data(), ssl->s3->alpn_selected.size()) || !CBB_flush(out)) { return false; } return true; } // Channel ID. // // https://tools.ietf.org/html/draft-balfanz-tls-channelid-01 static bool ext_channel_id_add_clienthello(const SSL_HANDSHAKE *hs, CBB *out, CBB *out_compressible, ssl_client_hello_type_t type) { const SSL *const ssl = hs->ssl; if (!hs->config->channel_id_private || SSL_is_dtls(ssl) || // Don't offer Channel ID in ClientHelloOuter. ClientHelloOuter handshakes // are not authenticated for the name that can learn the Channel ID. // // We could alternatively offer the extension but sign with a random key. // For other extensions, we try to align |ssl_client_hello_outer| and // |ssl_client_hello_unencrypted|, to improve the effectiveness of ECH // GREASE. However, Channel ID is deprecated and unlikely to be used with // ECH, so do the simplest thing. type == ssl_client_hello_outer) { return true; } if (!CBB_add_u16(out, TLSEXT_TYPE_channel_id) || !CBB_add_u16(out, 0 /* length */)) { return false; } return true; } static bool ext_channel_id_parse_serverhello(SSL_HANDSHAKE *hs, uint8_t *out_alert, CBS *contents) { if (contents == NULL) { return true; } assert(!SSL_is_dtls(hs->ssl)); assert(hs->config->channel_id_private); if (CBS_len(contents) != 0) { return false; } hs->channel_id_negotiated = true; return true; } static bool ext_channel_id_parse_clienthello(SSL_HANDSHAKE *hs, uint8_t *out_alert, CBS *contents) { SSL *const ssl = hs->ssl; if (contents == NULL || !hs->config->channel_id_enabled || SSL_is_dtls(ssl)) { return true; } if (CBS_len(contents) != 0) { return false; } hs->channel_id_negotiated = true; return true; } static bool ext_channel_id_add_serverhello(SSL_HANDSHAKE *hs, CBB *out) { if (!hs->channel_id_negotiated) { return true; } if (!CBB_add_u16(out, TLSEXT_TYPE_channel_id) || !CBB_add_u16(out, 0 /* length */)) { return false; } return true; } // Secure Real-time Transport Protocol (SRTP) extension. // // https://tools.ietf.org/html/rfc5764 static bool ext_srtp_add_clienthello(const SSL_HANDSHAKE *hs, CBB *out, CBB *out_compressible, ssl_client_hello_type_t type) { const SSL *const ssl = hs->ssl; const STACK_OF(SRTP_PROTECTION_PROFILE) *profiles = SSL_get_srtp_profiles(ssl); if (profiles == NULL || sk_SRTP_PROTECTION_PROFILE_num(profiles) == 0 || !SSL_is_dtls(ssl)) { return true; } CBB contents, profile_ids; if (!CBB_add_u16(out_compressible, TLSEXT_TYPE_srtp) || !CBB_add_u16_length_prefixed(out_compressible, &contents) || !CBB_add_u16_length_prefixed(&contents, &profile_ids)) { return false; } for (const SRTP_PROTECTION_PROFILE *profile : profiles) { if (!CBB_add_u16(&profile_ids, profile->id)) { return false; } } if (!CBB_add_u8(&contents, 0 /* empty use_mki value */) || !CBB_flush(out_compressible)) { return false; } return true; } static bool ext_srtp_parse_serverhello(SSL_HANDSHAKE *hs, uint8_t *out_alert, CBS *contents) { SSL *const ssl = hs->ssl; if (contents == NULL) { return true; } // The extension consists of a u16-prefixed profile ID list containing a // single uint16_t profile ID, then followed by a u8-prefixed srtp_mki field. // // See https://tools.ietf.org/html/rfc5764#section-4.1.1 assert(SSL_is_dtls(ssl)); CBS profile_ids, srtp_mki; uint16_t profile_id; if (!CBS_get_u16_length_prefixed(contents, &profile_ids) || !CBS_get_u16(&profile_ids, &profile_id) || CBS_len(&profile_ids) != 0 || !CBS_get_u8_length_prefixed(contents, &srtp_mki) || CBS_len(contents) != 0) { OPENSSL_PUT_ERROR(SSL, SSL_R_BAD_SRTP_PROTECTION_PROFILE_LIST); return false; } if (CBS_len(&srtp_mki) != 0) { // Must be no MKI, since we never offer one. OPENSSL_PUT_ERROR(SSL, SSL_R_BAD_SRTP_MKI_VALUE); *out_alert = SSL_AD_ILLEGAL_PARAMETER; return false; } // Check to see if the server gave us something we support and offered. for (const SRTP_PROTECTION_PROFILE *profile : SSL_get_srtp_profiles(ssl)) { if (profile->id == profile_id) { ssl->s3->srtp_profile = profile; return true; } } OPENSSL_PUT_ERROR(SSL, SSL_R_BAD_SRTP_PROTECTION_PROFILE_LIST); *out_alert = SSL_AD_ILLEGAL_PARAMETER; return false; } static bool ext_srtp_parse_clienthello(SSL_HANDSHAKE *hs, uint8_t *out_alert, CBS *contents) { SSL *const ssl = hs->ssl; // DTLS-SRTP is only defined for DTLS. if (contents == NULL || !SSL_is_dtls(ssl)) { return true; } CBS profile_ids, srtp_mki; if (!CBS_get_u16_length_prefixed(contents, &profile_ids) || CBS_len(&profile_ids) < 2 || !CBS_get_u8_length_prefixed(contents, &srtp_mki) || CBS_len(contents) != 0) { OPENSSL_PUT_ERROR(SSL, SSL_R_BAD_SRTP_PROTECTION_PROFILE_LIST); return false; } // Discard the MKI value for now. const STACK_OF(SRTP_PROTECTION_PROFILE) *server_profiles = SSL_get_srtp_profiles(ssl); // Pick the server's most preferred profile. for (const SRTP_PROTECTION_PROFILE *server_profile : server_profiles) { CBS profile_ids_tmp; CBS_init(&profile_ids_tmp, CBS_data(&profile_ids), CBS_len(&profile_ids)); while (CBS_len(&profile_ids_tmp) > 0) { uint16_t profile_id; if (!CBS_get_u16(&profile_ids_tmp, &profile_id)) { return false; } if (server_profile->id == profile_id) { ssl->s3->srtp_profile = server_profile; return true; } } } return true; } static bool ext_srtp_add_serverhello(SSL_HANDSHAKE *hs, CBB *out) { SSL *const ssl = hs->ssl; if (ssl->s3->srtp_profile == NULL) { return true; } assert(SSL_is_dtls(ssl)); CBB contents, profile_ids; if (!CBB_add_u16(out, TLSEXT_TYPE_srtp) || !CBB_add_u16_length_prefixed(out, &contents) || !CBB_add_u16_length_prefixed(&contents, &profile_ids) || !CBB_add_u16(&profile_ids, ssl->s3->srtp_profile->id) || !CBB_add_u8(&contents, 0 /* empty MKI */) || !CBB_flush(out)) { return false; } return true; } // EC point formats. // // https://tools.ietf.org/html/rfc4492#section-5.1.2 static bool ext_ec_point_add_extension(const SSL_HANDSHAKE *hs, CBB *out) { CBB contents, formats; if (!CBB_add_u16(out, TLSEXT_TYPE_ec_point_formats) || !CBB_add_u16_length_prefixed(out, &contents) || !CBB_add_u8_length_prefixed(&contents, &formats) || !CBB_add_u8(&formats, TLSEXT_ECPOINTFORMAT_uncompressed) || !CBB_flush(out)) { return false; } return true; } static bool ext_ec_point_add_clienthello(const SSL_HANDSHAKE *hs, CBB *out, CBB *out_compressible, ssl_client_hello_type_t type) { // The point format extension is unnecessary in TLS 1.3. if (hs->min_version >= TLS1_3_VERSION || type == ssl_client_hello_inner) { return true; } return ext_ec_point_add_extension(hs, out); } static bool ext_ec_point_parse_serverhello(SSL_HANDSHAKE *hs, uint8_t *out_alert, CBS *contents) { if (contents == NULL) { return true; } if (ssl_protocol_version(hs->ssl) >= TLS1_3_VERSION) { return false; } CBS ec_point_format_list; if (!CBS_get_u8_length_prefixed(contents, &ec_point_format_list) || CBS_len(contents) != 0) { return false; } // Per RFC 4492, section 5.1.2, implementations MUST support the uncompressed // point format. if (OPENSSL_memchr(CBS_data(&ec_point_format_list), TLSEXT_ECPOINTFORMAT_uncompressed, CBS_len(&ec_point_format_list)) == NULL) { *out_alert = SSL_AD_ILLEGAL_PARAMETER; return false; } return true; } static bool ext_ec_point_parse_clienthello(SSL_HANDSHAKE *hs, uint8_t *out_alert, CBS *contents) { if (ssl_protocol_version(hs->ssl) >= TLS1_3_VERSION) { return true; } return ext_ec_point_parse_serverhello(hs, out_alert, contents); } static bool ext_ec_point_add_serverhello(SSL_HANDSHAKE *hs, CBB *out) { SSL *const ssl = hs->ssl; if (ssl_protocol_version(ssl) >= TLS1_3_VERSION) { return true; } const uint32_t alg_k = hs->new_cipher->algorithm_mkey; const uint32_t alg_a = hs->new_cipher->algorithm_auth; const bool using_ecc = (alg_k & SSL_kECDHE) || (alg_a & SSL_aECDSA); if (!using_ecc) { return true; } return ext_ec_point_add_extension(hs, out); } // Pre Shared Key // // https://tools.ietf.org/html/rfc8446#section-4.2.11 static bool should_offer_psk(const SSL_HANDSHAKE *hs, ssl_client_hello_type_t type) { const SSL *const ssl = hs->ssl; if (hs->max_version < TLS1_3_VERSION || ssl->session == nullptr || ssl_session_protocol_version(ssl->session.get()) < TLS1_3_VERSION || // TODO(https://crbug.com/boringssl/275): Should we synthesize a // placeholder PSK, at least when we offer early data? Otherwise // ClientHelloOuter will contain an early_data extension without a // pre_shared_key extension and potentially break the recovery flow. type == ssl_client_hello_outer) { return false; } // Per RFC 8446 section 4.1.4, skip offering the session if the selected // cipher in HelloRetryRequest does not match. This avoids performing the // transcript hash transformation for multiple hashes. if (ssl->s3->used_hello_retry_request && ssl->session->cipher->algorithm_prf != hs->new_cipher->algorithm_prf) { return false; } return true; } static size_t ext_pre_shared_key_clienthello_length( const SSL_HANDSHAKE *hs, ssl_client_hello_type_t type) { const SSL *const ssl = hs->ssl; if (!should_offer_psk(hs, type)) { return 0; } size_t binder_len = EVP_MD_size(ssl_session_get_digest(ssl->session.get())); return 15 + ssl->session->ticket.size() + binder_len; } static bool ext_pre_shared_key_add_clienthello(const SSL_HANDSHAKE *hs, CBB *out, bool *out_needs_binder, ssl_client_hello_type_t type) { const SSL *const ssl = hs->ssl; *out_needs_binder = false; if (!should_offer_psk(hs, type)) { return true; } struct OPENSSL_timeval now; ssl_get_current_time(ssl, &now); uint32_t ticket_age = 1000 * (now.tv_sec - ssl->session->time); uint32_t obfuscated_ticket_age = ticket_age + ssl->session->ticket_age_add; // Fill in a placeholder zero binder of the appropriate length. It will be // computed and filled in later after length prefixes are computed. size_t binder_len = EVP_MD_size(ssl_session_get_digest(ssl->session.get())); CBB contents, identity, ticket, binders, binder; if (!CBB_add_u16(out, TLSEXT_TYPE_pre_shared_key) || !CBB_add_u16_length_prefixed(out, &contents) || !CBB_add_u16_length_prefixed(&contents, &identity) || !CBB_add_u16_length_prefixed(&identity, &ticket) || !CBB_add_bytes(&ticket, ssl->session->ticket.data(), ssl->session->ticket.size()) || !CBB_add_u32(&identity, obfuscated_ticket_age) || !CBB_add_u16_length_prefixed(&contents, &binders) || !CBB_add_u8_length_prefixed(&binders, &binder) || !CBB_add_zeros(&binder, binder_len)) { return false; } *out_needs_binder = true; return CBB_flush(out); } bool ssl_ext_pre_shared_key_parse_serverhello(SSL_HANDSHAKE *hs, uint8_t *out_alert, CBS *contents) { uint16_t psk_id; if (!CBS_get_u16(contents, &psk_id) || CBS_len(contents) != 0) { OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR); *out_alert = SSL_AD_DECODE_ERROR; return false; } // We only advertise one PSK identity, so the only legal index is zero. if (psk_id != 0) { OPENSSL_PUT_ERROR(SSL, SSL_R_PSK_IDENTITY_NOT_FOUND); *out_alert = SSL_AD_UNKNOWN_PSK_IDENTITY; return false; } return true; } bool ssl_ext_pre_shared_key_parse_clienthello( SSL_HANDSHAKE *hs, CBS *out_ticket, CBS *out_binders, uint32_t *out_obfuscated_ticket_age, uint8_t *out_alert, const SSL_CLIENT_HELLO *client_hello, CBS *contents) { // Verify that the pre_shared_key extension is the last extension in // ClientHello. if (CBS_data(contents) + CBS_len(contents) != client_hello->extensions + client_hello->extensions_len) { OPENSSL_PUT_ERROR(SSL, SSL_R_PRE_SHARED_KEY_MUST_BE_LAST); *out_alert = SSL_AD_ILLEGAL_PARAMETER; return false; } // We only process the first PSK identity since we don't support pure PSK. CBS identities, binders; if (!CBS_get_u16_length_prefixed(contents, &identities) || !CBS_get_u16_length_prefixed(&identities, out_ticket) || !CBS_get_u32(&identities, out_obfuscated_ticket_age) || !CBS_get_u16_length_prefixed(contents, &binders) || CBS_len(&binders) == 0 || CBS_len(contents) != 0) { OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR); *out_alert = SSL_AD_DECODE_ERROR; return false; } *out_binders = binders; // Check the syntax of the remaining identities, but do not process them. size_t num_identities = 1; while (CBS_len(&identities) != 0) { CBS unused_ticket; uint32_t unused_obfuscated_ticket_age; if (!CBS_get_u16_length_prefixed(&identities, &unused_ticket) || !CBS_get_u32(&identities, &unused_obfuscated_ticket_age)) { OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR); *out_alert = SSL_AD_DECODE_ERROR; return false; } num_identities++; } // Check the syntax of the binders. The value will be checked later if // resuming. size_t num_binders = 0; while (CBS_len(&binders) != 0) { CBS binder; if (!CBS_get_u8_length_prefixed(&binders, &binder)) { OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR); *out_alert = SSL_AD_DECODE_ERROR; return false; } num_binders++; } if (num_identities != num_binders) { OPENSSL_PUT_ERROR(SSL, SSL_R_PSK_IDENTITY_BINDER_COUNT_MISMATCH); *out_alert = SSL_AD_ILLEGAL_PARAMETER; return false; } return true; } bool ssl_ext_pre_shared_key_add_serverhello(SSL_HANDSHAKE *hs, CBB *out) { if (!hs->ssl->s3->session_reused) { return true; } CBB contents; if (!CBB_add_u16(out, TLSEXT_TYPE_pre_shared_key) || !CBB_add_u16_length_prefixed(out, &contents) || // We only consider the first identity for resumption !CBB_add_u16(&contents, 0) || !CBB_flush(out)) { return false; } return true; } // Pre-Shared Key Exchange Modes // // https://tools.ietf.org/html/rfc8446#section-4.2.9 static bool ext_psk_key_exchange_modes_add_clienthello( const SSL_HANDSHAKE *hs, CBB *out, CBB *out_compressible, ssl_client_hello_type_t type) { if (hs->max_version < TLS1_3_VERSION) { return true; } CBB contents, ke_modes; if (!CBB_add_u16(out_compressible, TLSEXT_TYPE_psk_key_exchange_modes) || !CBB_add_u16_length_prefixed(out_compressible, &contents) || !CBB_add_u8_length_prefixed(&contents, &ke_modes) || !CBB_add_u8(&ke_modes, SSL_PSK_DHE_KE)) { return false; } return CBB_flush(out_compressible); } static bool ext_psk_key_exchange_modes_parse_clienthello(SSL_HANDSHAKE *hs, uint8_t *out_alert, CBS *contents) { if (contents == NULL) { return true; } CBS ke_modes; if (!CBS_get_u8_length_prefixed(contents, &ke_modes) || CBS_len(&ke_modes) == 0 || CBS_len(contents) != 0) { *out_alert = SSL_AD_DECODE_ERROR; return false; } // We only support tickets with PSK_DHE_KE. hs->accept_psk_mode = OPENSSL_memchr(CBS_data(&ke_modes), SSL_PSK_DHE_KE, CBS_len(&ke_modes)) != NULL; return true; } // Early Data Indication // // https://tools.ietf.org/html/rfc8446#section-4.2.10 static bool ext_early_data_add_clienthello(const SSL_HANDSHAKE *hs, CBB *out, CBB *out_compressible, ssl_client_hello_type_t type) { const SSL *const ssl = hs->ssl; // The second ClientHello never offers early data, and we must have already // filled in |early_data_reason| by this point. if (ssl->s3->used_hello_retry_request) { assert(ssl->s3->early_data_reason != ssl_early_data_unknown); return true; } if (!hs->early_data_offered) { return true; } // If offering ECH, the extension only applies to ClientHelloInner, but we // send the extension in both ClientHellos. This ensures that, if the server // handshakes with ClientHelloOuter, it can skip past early data. See // draft-ietf-tls-esni-13, section 6.1. if (!CBB_add_u16(out_compressible, TLSEXT_TYPE_early_data) || !CBB_add_u16(out_compressible, 0) || !CBB_flush(out_compressible)) { return false; } return true; } static bool ext_early_data_parse_serverhello(SSL_HANDSHAKE *hs, uint8_t *out_alert, CBS *contents) { SSL *const ssl = hs->ssl; if (contents == NULL) { if (hs->early_data_offered && !ssl->s3->used_hello_retry_request) { ssl->s3->early_data_reason = ssl->s3->session_reused ? ssl_early_data_peer_declined : ssl_early_data_session_not_resumed; } else { // We already filled in |early_data_reason| when declining to offer 0-RTT // or handling the implicit HelloRetryRequest reject. assert(ssl->s3->early_data_reason != ssl_early_data_unknown); } return true; } // If we received an HRR, the second ClientHello never offers early data, so // the extensions logic will automatically reject early data extensions as // unsolicited. This covered by the ServerAcceptsEarlyDataOnHRR test. assert(!ssl->s3->used_hello_retry_request); if (CBS_len(contents) != 0) { *out_alert = SSL_AD_DECODE_ERROR; return false; } if (!ssl->s3->session_reused) { *out_alert = SSL_AD_UNSUPPORTED_EXTENSION; OPENSSL_PUT_ERROR(SSL, SSL_R_UNEXPECTED_EXTENSION); return false; } ssl->s3->early_data_reason = ssl_early_data_accepted; ssl->s3->early_data_accepted = true; return true; } static bool ext_early_data_parse_clienthello(SSL_HANDSHAKE *hs, uint8_t *out_alert, CBS *contents) { SSL *const ssl = hs->ssl; if (contents == NULL || ssl_protocol_version(ssl) < TLS1_3_VERSION) { return true; } if (CBS_len(contents) != 0) { *out_alert = SSL_AD_DECODE_ERROR; return false; } hs->early_data_offered = true; return true; } static bool ext_early_data_add_serverhello(SSL_HANDSHAKE *hs, CBB *out) { if (!hs->ssl->s3->early_data_accepted) { return true; } if (!CBB_add_u16(out, TLSEXT_TYPE_early_data) || !CBB_add_u16(out, 0) || !CBB_flush(out)) { return false; } return true; } // Key Share // // https://tools.ietf.org/html/rfc8446#section-4.2.8 bool ssl_setup_key_shares(SSL_HANDSHAKE *hs, uint16_t override_group_id) { SSL *const ssl = hs->ssl; hs->key_shares[0].reset(); hs->key_shares[1].reset(); hs->key_share_bytes.Reset(); if (hs->max_version < TLS1_3_VERSION) { return true; } bssl::ScopedCBB cbb; if (!CBB_init(cbb.get(), 64)) { return false; } if (override_group_id == 0 && ssl->ctx->grease_enabled) { // Add a fake group. See RFC 8701. if (!CBB_add_u16(cbb.get(), ssl_get_grease_value(hs, ssl_grease_group)) || !CBB_add_u16(cbb.get(), 1 /* length */) || !CBB_add_u8(cbb.get(), 0 /* one byte key share */)) { return false; } } uint16_t group_id = override_group_id; uint16_t second_group_id = 0; if (override_group_id == 0) { // Predict the most preferred group. Span<const uint16_t> groups = tls1_get_grouplist(hs); if (groups.empty()) { OPENSSL_PUT_ERROR(SSL, SSL_R_NO_GROUPS_SPECIFIED); return false; } group_id = groups[0]; if (is_post_quantum_group(group_id) && groups.size() >= 2) { // CECPQ2(b) is not sent as the only initial key share. We'll include the // 2nd preference group too to avoid round-trips. second_group_id = groups[1]; assert(second_group_id != group_id); } } CBB key_exchange; hs->key_shares[0] = SSLKeyShare::Create(group_id); if (!hs->key_shares[0] || // !CBB_add_u16(cbb.get(), group_id) || !CBB_add_u16_length_prefixed(cbb.get(), &key_exchange) || !hs->key_shares[0]->Offer(&key_exchange)) { return false; } if (second_group_id != 0) { hs->key_shares[1] = SSLKeyShare::Create(second_group_id); if (!hs->key_shares[1] || // !CBB_add_u16(cbb.get(), second_group_id) || !CBB_add_u16_length_prefixed(cbb.get(), &key_exchange) || !hs->key_shares[1]->Offer(&key_exchange)) { return false; } } return CBBFinishArray(cbb.get(), &hs->key_share_bytes); } static bool ext_key_share_add_clienthello(const SSL_HANDSHAKE *hs, CBB *out, CBB *out_compressible, ssl_client_hello_type_t type) { if (hs->max_version < TLS1_3_VERSION) { return true; } assert(!hs->key_share_bytes.empty()); CBB contents, kse_bytes; if (!CBB_add_u16(out_compressible, TLSEXT_TYPE_key_share) || !CBB_add_u16_length_prefixed(out_compressible, &contents) || !CBB_add_u16_length_prefixed(&contents, &kse_bytes) || !CBB_add_bytes(&kse_bytes, hs->key_share_bytes.data(), hs->key_share_bytes.size()) || !CBB_flush(out_compressible)) { return false; } return true; } bool ssl_ext_key_share_parse_serverhello(SSL_HANDSHAKE *hs, Array<uint8_t> *out_secret, uint8_t *out_alert, CBS *contents) { CBS peer_key; uint16_t group_id; if (!CBS_get_u16(contents, &group_id) || !CBS_get_u16_length_prefixed(contents, &peer_key) || CBS_len(contents) != 0) { OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR); *out_alert = SSL_AD_DECODE_ERROR; return false; } SSLKeyShare *key_share = hs->key_shares[0].get(); if (key_share->GroupID() != group_id) { if (!hs->key_shares[1] || hs->key_shares[1]->GroupID() != group_id) { *out_alert = SSL_AD_ILLEGAL_PARAMETER; OPENSSL_PUT_ERROR(SSL, SSL_R_WRONG_CURVE); return false; } key_share = hs->key_shares[1].get(); } if (!key_share->Finish(out_secret, out_alert, peer_key)) { *out_alert = SSL_AD_INTERNAL_ERROR; return false; } hs->new_session->group_id = group_id; hs->key_shares[0].reset(); hs->key_shares[1].reset(); return true; } bool ssl_ext_key_share_parse_clienthello(SSL_HANDSHAKE *hs, bool *out_found, Span<const uint8_t> *out_peer_key, uint8_t *out_alert, const SSL_CLIENT_HELLO *client_hello) { // We only support connections that include an ECDHE key exchange. CBS contents; if (!ssl_client_hello_get_extension(client_hello, &contents, TLSEXT_TYPE_key_share)) { OPENSSL_PUT_ERROR(SSL, SSL_R_MISSING_KEY_SHARE); *out_alert = SSL_AD_MISSING_EXTENSION; return false; } CBS key_shares; if (!CBS_get_u16_length_prefixed(&contents, &key_shares) || CBS_len(&contents) != 0) { OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR); return false; } // Find the corresponding key share. const uint16_t group_id = hs->new_session->group_id; CBS peer_key; CBS_init(&peer_key, nullptr, 0); while (CBS_len(&key_shares) > 0) { uint16_t id; CBS peer_key_tmp; if (!CBS_get_u16(&key_shares, &id) || !CBS_get_u16_length_prefixed(&key_shares, &peer_key_tmp) || CBS_len(&peer_key_tmp) == 0) { OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR); return false; } if (id == group_id) { if (CBS_len(&peer_key) != 0) { OPENSSL_PUT_ERROR(SSL, SSL_R_DUPLICATE_KEY_SHARE); *out_alert = SSL_AD_ILLEGAL_PARAMETER; return false; } peer_key = peer_key_tmp; // Continue parsing the structure to keep peers honest. } } if (out_peer_key != nullptr) { *out_peer_key = peer_key; } *out_found = CBS_len(&peer_key) != 0; return true; } bool ssl_ext_key_share_add_serverhello(SSL_HANDSHAKE *hs, CBB *out) { CBB kse_bytes, public_key; if (!CBB_add_u16(out, TLSEXT_TYPE_key_share) || !CBB_add_u16_length_prefixed(out, &kse_bytes) || !CBB_add_u16(&kse_bytes, hs->new_session->group_id) || !CBB_add_u16_length_prefixed(&kse_bytes, &public_key) || !CBB_add_bytes(&public_key, hs->ecdh_public_key.data(), hs->ecdh_public_key.size()) || !CBB_flush(out)) { return false; } return true; } // Supported Versions // // https://tools.ietf.org/html/rfc8446#section-4.2.1 static bool ext_supported_versions_add_clienthello( const SSL_HANDSHAKE *hs, CBB *out, CBB *out_compressible, ssl_client_hello_type_t type) { const SSL *const ssl = hs->ssl; if (hs->max_version <= TLS1_2_VERSION) { return true; } // supported_versions is compressible in ECH if ClientHelloOuter already // requires TLS 1.3. Otherwise the extensions differ in the older versions. if (hs->min_version >= TLS1_3_VERSION) { out = out_compressible; } CBB contents, versions; if (!CBB_add_u16(out, TLSEXT_TYPE_supported_versions) || !CBB_add_u16_length_prefixed(out, &contents) || !CBB_add_u8_length_prefixed(&contents, &versions)) { return false; } // Add a fake version. See RFC 8701. if (ssl->ctx->grease_enabled && !CBB_add_u16(&versions, ssl_get_grease_value(hs, ssl_grease_version))) { return false; } // Encrypted ClientHellos requires TLS 1.3 or later. uint16_t extra_min_version = type == ssl_client_hello_inner ? TLS1_3_VERSION : 0; if (!ssl_add_supported_versions(hs, &versions, extra_min_version) || !CBB_flush(out)) { return false; } return true; } // Cookie // // https://tools.ietf.org/html/rfc8446#section-4.2.2 static bool ext_cookie_add_clienthello(const SSL_HANDSHAKE *hs, CBB *out, CBB *out_compressible, ssl_client_hello_type_t type) { if (hs->cookie.empty()) { return true; } CBB contents, cookie; if (!CBB_add_u16(out_compressible, TLSEXT_TYPE_cookie) || !CBB_add_u16_length_prefixed(out_compressible, &contents) || !CBB_add_u16_length_prefixed(&contents, &cookie) || !CBB_add_bytes(&cookie, hs->cookie.data(), hs->cookie.size()) || !CBB_flush(out_compressible)) { return false; } return true; } // Supported Groups // // https://tools.ietf.org/html/rfc4492#section-5.1.1 // https://tools.ietf.org/html/rfc8446#section-4.2.7 static bool ext_supported_groups_add_clienthello(const SSL_HANDSHAKE *hs, CBB *out, CBB *out_compressible, ssl_client_hello_type_t type) { const SSL *const ssl = hs->ssl; CBB contents, groups_bytes; if (!CBB_add_u16(out_compressible, TLSEXT_TYPE_supported_groups) || !CBB_add_u16_length_prefixed(out_compressible, &contents) || !CBB_add_u16_length_prefixed(&contents, &groups_bytes)) { return false; } // Add a fake group. See RFC 8701. if (ssl->ctx->grease_enabled && !CBB_add_u16(&groups_bytes, ssl_get_grease_value(hs, ssl_grease_group))) { return false; } for (uint16_t group : tls1_get_grouplist(hs)) { if (is_post_quantum_group(group) && hs->max_version < TLS1_3_VERSION) { continue; } if (!CBB_add_u16(&groups_bytes, group)) { return false; } } return CBB_flush(out_compressible); } static bool ext_supported_groups_parse_serverhello(SSL_HANDSHAKE *hs, uint8_t *out_alert, CBS *contents) { // This extension is not expected to be echoed by servers in TLS 1.2, but some // BigIP servers send it nonetheless, so do not enforce this. return true; } static bool parse_u16_array(const CBS *cbs, Array<uint16_t> *out) { CBS copy = *cbs; if ((CBS_len(©) & 1) != 0) { OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR); return false; } Array<uint16_t> ret; if (!ret.Init(CBS_len(©) / 2)) { return false; } for (size_t i = 0; i < ret.size(); i++) { if (!CBS_get_u16(©, &ret[i])) { OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR); return false; } } assert(CBS_len(©) == 0); *out = std::move(ret); return 1; } static bool ext_supported_groups_parse_clienthello(SSL_HANDSHAKE *hs, uint8_t *out_alert, CBS *contents) { if (contents == NULL) { return true; } CBS supported_group_list; if (!CBS_get_u16_length_prefixed(contents, &supported_group_list) || CBS_len(&supported_group_list) == 0 || CBS_len(contents) != 0 || !parse_u16_array(&supported_group_list, &hs->peer_supported_group_list)) { return false; } return true; } // QUIC Transport Parameters static bool ext_quic_transport_params_add_clienthello_impl( const SSL_HANDSHAKE *hs, CBB *out, bool use_legacy_codepoint) { if (hs->config->quic_transport_params.empty() && !hs->ssl->quic_method) { return true; } if (hs->config->quic_transport_params.empty() || !hs->ssl->quic_method) { // QUIC Transport Parameters must be sent over QUIC, and they must not be // sent over non-QUIC transports. If transport params are set, then // SSL(_CTX)_set_quic_method must also be called. OPENSSL_PUT_ERROR(SSL, SSL_R_QUIC_TRANSPORT_PARAMETERS_MISCONFIGURED); return false; } assert(hs->min_version > TLS1_2_VERSION); if (use_legacy_codepoint != hs->config->quic_use_legacy_codepoint) { // Do nothing, we'll send the other codepoint. return true; } uint16_t extension_type = TLSEXT_TYPE_quic_transport_parameters; if (hs->config->quic_use_legacy_codepoint) { extension_type = TLSEXT_TYPE_quic_transport_parameters_legacy; } CBB contents; if (!CBB_add_u16(out, extension_type) || !CBB_add_u16_length_prefixed(out, &contents) || !CBB_add_bytes(&contents, hs->config->quic_transport_params.data(), hs->config->quic_transport_params.size()) || !CBB_flush(out)) { return false; } return true; } static bool ext_quic_transport_params_add_clienthello( const SSL_HANDSHAKE *hs, CBB *out, CBB *out_compressible, ssl_client_hello_type_t type) { return ext_quic_transport_params_add_clienthello_impl( hs, out_compressible, /*use_legacy_codepoint=*/false); } static bool ext_quic_transport_params_add_clienthello_legacy( const SSL_HANDSHAKE *hs, CBB *out, CBB *out_compressible, ssl_client_hello_type_t type) { return ext_quic_transport_params_add_clienthello_impl( hs, out_compressible, /*use_legacy_codepoint=*/true); } static bool ext_quic_transport_params_parse_serverhello_impl( SSL_HANDSHAKE *hs, uint8_t *out_alert, CBS *contents, bool used_legacy_codepoint) { SSL *const ssl = hs->ssl; if (contents == nullptr) { if (used_legacy_codepoint != hs->config->quic_use_legacy_codepoint) { // Silently ignore because we expect the other QUIC codepoint. return true; } if (!ssl->quic_method) { return true; } *out_alert = SSL_AD_MISSING_EXTENSION; return false; } // The extensions parser will check for unsolicited extensions before // calling the callback. assert(ssl->quic_method != nullptr); assert(ssl_protocol_version(ssl) == TLS1_3_VERSION); assert(used_legacy_codepoint == hs->config->quic_use_legacy_codepoint); return ssl->s3->peer_quic_transport_params.CopyFrom(*contents); } static bool ext_quic_transport_params_parse_serverhello(SSL_HANDSHAKE *hs, uint8_t *out_alert, CBS *contents) { return ext_quic_transport_params_parse_serverhello_impl( hs, out_alert, contents, /*used_legacy_codepoint=*/false); } static bool ext_quic_transport_params_parse_serverhello_legacy( SSL_HANDSHAKE *hs, uint8_t *out_alert, CBS *contents) { return ext_quic_transport_params_parse_serverhello_impl( hs, out_alert, contents, /*used_legacy_codepoint=*/true); } static bool ext_quic_transport_params_parse_clienthello_impl( SSL_HANDSHAKE *hs, uint8_t *out_alert, CBS *contents, bool used_legacy_codepoint) { SSL *const ssl = hs->ssl; if (!contents) { if (!ssl->quic_method) { if (hs->config->quic_transport_params.empty()) { return true; } // QUIC transport parameters must not be set if |ssl| is not configured // for QUIC. OPENSSL_PUT_ERROR(SSL, SSL_R_QUIC_TRANSPORT_PARAMETERS_MISCONFIGURED); *out_alert = SSL_AD_INTERNAL_ERROR; return false; } if (used_legacy_codepoint != hs->config->quic_use_legacy_codepoint) { // Silently ignore because we expect the other QUIC codepoint. return true; } *out_alert = SSL_AD_MISSING_EXTENSION; return false; } if (!ssl->quic_method) { if (used_legacy_codepoint) { // Ignore the legacy private-use codepoint because that could be sent // to mean something else than QUIC transport parameters. return true; } // Fail if we received the codepoint registered with IANA for QUIC // because that is not allowed outside of QUIC. *out_alert = SSL_AD_UNSUPPORTED_EXTENSION; return false; } assert(ssl_protocol_version(ssl) == TLS1_3_VERSION); if (used_legacy_codepoint != hs->config->quic_use_legacy_codepoint) { // Silently ignore because we expect the other QUIC codepoint. return true; } return ssl->s3->peer_quic_transport_params.CopyFrom(*contents); } static bool ext_quic_transport_params_parse_clienthello(SSL_HANDSHAKE *hs, uint8_t *out_alert, CBS *contents) { return ext_quic_transport_params_parse_clienthello_impl( hs, out_alert, contents, /*used_legacy_codepoint=*/false); } static bool ext_quic_transport_params_parse_clienthello_legacy( SSL_HANDSHAKE *hs, uint8_t *out_alert, CBS *contents) { return ext_quic_transport_params_parse_clienthello_impl( hs, out_alert, contents, /*used_legacy_codepoint=*/true); } static bool ext_quic_transport_params_add_serverhello_impl( SSL_HANDSHAKE *hs, CBB *out, bool use_legacy_codepoint) { if (hs->ssl->quic_method == nullptr && use_legacy_codepoint) { // Ignore the legacy private-use codepoint because that could be sent // to mean something else than QUIC transport parameters. return true; } assert(hs->ssl->quic_method != nullptr); if (hs->config->quic_transport_params.empty()) { // Transport parameters must be set when using QUIC. OPENSSL_PUT_ERROR(SSL, SSL_R_QUIC_TRANSPORT_PARAMETERS_MISCONFIGURED); return false; } if (use_legacy_codepoint != hs->config->quic_use_legacy_codepoint) { // Do nothing, we'll send the other codepoint. return true; } uint16_t extension_type = TLSEXT_TYPE_quic_transport_parameters; if (hs->config->quic_use_legacy_codepoint) { extension_type = TLSEXT_TYPE_quic_transport_parameters_legacy; } CBB contents; if (!CBB_add_u16(out, extension_type) || !CBB_add_u16_length_prefixed(out, &contents) || !CBB_add_bytes(&contents, hs->config->quic_transport_params.data(), hs->config->quic_transport_params.size()) || !CBB_flush(out)) { return false; } return true; } static bool ext_quic_transport_params_add_serverhello(SSL_HANDSHAKE *hs, CBB *out) { return ext_quic_transport_params_add_serverhello_impl( hs, out, /*use_legacy_codepoint=*/false); } static bool ext_quic_transport_params_add_serverhello_legacy(SSL_HANDSHAKE *hs, CBB *out) { return ext_quic_transport_params_add_serverhello_impl( hs, out, /*use_legacy_codepoint=*/true); } // Delegated credentials. // // https://tools.ietf.org/html/draft-ietf-tls-subcerts static bool ext_delegated_credential_add_clienthello( const SSL_HANDSHAKE *hs, CBB *out, CBB *out_compressible, ssl_client_hello_type_t type) { return true; } static bool ext_delegated_credential_parse_clienthello(SSL_HANDSHAKE *hs, uint8_t *out_alert, CBS *contents) { if (contents == nullptr || ssl_protocol_version(hs->ssl) < TLS1_3_VERSION) { // Don't use delegated credentials unless we're negotiating TLS 1.3 or // higher. return true; } // The contents of the extension are the signature algorithms the client will // accept for a delegated credential. CBS sigalg_list; if (!CBS_get_u16_length_prefixed(contents, &sigalg_list) || CBS_len(&sigalg_list) == 0 || CBS_len(contents) != 0 || !parse_u16_array(&sigalg_list, &hs->peer_delegated_credential_sigalgs)) { return false; } hs->delegated_credential_requested = true; return true; } // Certificate compression static bool cert_compression_add_clienthello(const SSL_HANDSHAKE *hs, CBB *out, CBB *out_compressible, ssl_client_hello_type_t type) { bool first = true; CBB contents, algs; for (const auto &alg : hs->ssl->ctx->cert_compression_algs) { if (alg.decompress == nullptr) { continue; } if (first && (!CBB_add_u16(out_compressible, TLSEXT_TYPE_cert_compression) || !CBB_add_u16_length_prefixed(out_compressible, &contents) || !CBB_add_u8_length_prefixed(&contents, &algs))) { return false; } first = false; if (!CBB_add_u16(&algs, alg.alg_id)) { return false; } } return first || CBB_flush(out_compressible); } static bool cert_compression_parse_serverhello(SSL_HANDSHAKE *hs, uint8_t *out_alert, CBS *contents) { if (contents == nullptr) { return true; } // The server may not echo this extension. Any server to client negotiation is // advertised in the CertificateRequest message. return false; } static bool cert_compression_parse_clienthello(SSL_HANDSHAKE *hs, uint8_t *out_alert, CBS *contents) { if (contents == nullptr) { return true; } const SSL_CTX *ctx = hs->ssl->ctx.get(); const size_t num_algs = ctx->cert_compression_algs.size(); CBS alg_ids; if (!CBS_get_u8_length_prefixed(contents, &alg_ids) || CBS_len(contents) != 0 || CBS_len(&alg_ids) == 0 || CBS_len(&alg_ids) % 2 == 1) { return false; } const size_t num_given_alg_ids = CBS_len(&alg_ids) / 2; Array<uint16_t> given_alg_ids; if (!given_alg_ids.Init(num_given_alg_ids)) { return false; } size_t best_index = num_algs; size_t given_alg_idx = 0; while (CBS_len(&alg_ids) > 0) { uint16_t alg_id; if (!CBS_get_u16(&alg_ids, &alg_id)) { return false; } given_alg_ids[given_alg_idx++] = alg_id; for (size_t i = 0; i < num_algs; i++) { const auto &alg = ctx->cert_compression_algs[i]; if (alg.alg_id == alg_id && alg.compress != nullptr) { if (i < best_index) { best_index = i; } break; } } } qsort(given_alg_ids.data(), given_alg_ids.size(), sizeof(uint16_t), compare_uint16_t); for (size_t i = 1; i < num_given_alg_ids; i++) { if (given_alg_ids[i - 1] == given_alg_ids[i]) { return false; } } if (best_index < num_algs && ssl_protocol_version(hs->ssl) >= TLS1_3_VERSION) { hs->cert_compression_negotiated = true; hs->cert_compression_alg_id = ctx->cert_compression_algs[best_index].alg_id; } return true; } static bool cert_compression_add_serverhello(SSL_HANDSHAKE *hs, CBB *out) { return true; } // Application-level Protocol Settings // // https://tools.ietf.org/html/draft-vvv-tls-alps-01 bool ssl_get_local_application_settings(const SSL_HANDSHAKE *hs, Span<const uint8_t> *out_settings, Span<const uint8_t> protocol) { for (const ALPSConfig &config : hs->config->alps_configs) { if (protocol == config.protocol) { *out_settings = config.settings; return true; } } return false; } static bool ext_alps_add_clienthello(const SSL_HANDSHAKE *hs, CBB *out, CBB *out_compressible, ssl_client_hello_type_t type) { const SSL *const ssl = hs->ssl; if (// ALPS requires TLS 1.3. hs->max_version < TLS1_3_VERSION || // Do not offer ALPS without ALPN. hs->config->alpn_client_proto_list.empty() || // Do not offer ALPS if not configured. hs->config->alps_configs.empty() || // Do not offer ALPS on renegotiation handshakes. ssl->s3->initial_handshake_complete) { return true; } CBB contents, proto_list, proto; if (!CBB_add_u16(out_compressible, TLSEXT_TYPE_application_settings) || !CBB_add_u16_length_prefixed(out_compressible, &contents) || !CBB_add_u16_length_prefixed(&contents, &proto_list)) { return false; } for (const ALPSConfig &config : hs->config->alps_configs) { if (!CBB_add_u8_length_prefixed(&proto_list, &proto) || !CBB_add_bytes(&proto, config.protocol.data(), config.protocol.size())) { return false; } } return CBB_flush(out_compressible); } static bool ext_alps_parse_serverhello(SSL_HANDSHAKE *hs, uint8_t *out_alert, CBS *contents) { SSL *const ssl = hs->ssl; if (contents == nullptr) { return true; } assert(!ssl->s3->initial_handshake_complete); assert(!hs->config->alpn_client_proto_list.empty()); assert(!hs->config->alps_configs.empty()); // ALPS requires TLS 1.3. if (ssl_protocol_version(ssl) < TLS1_3_VERSION) { *out_alert = SSL_AD_UNSUPPORTED_EXTENSION; OPENSSL_PUT_ERROR(SSL, SSL_R_UNEXPECTED_EXTENSION); return false; } // Note extension callbacks may run in any order, so we defer checking // consistency with ALPN to |ssl_check_serverhello_tlsext|. if (!hs->new_session->peer_application_settings.CopyFrom(*contents)) { *out_alert = SSL_AD_INTERNAL_ERROR; return false; } hs->new_session->has_application_settings = true; return true; } static bool ext_alps_add_serverhello(SSL_HANDSHAKE *hs, CBB *out) { SSL *const ssl = hs->ssl; // If early data is accepted, we omit the ALPS extension. It is implicitly // carried over from the previous connection. if (hs->new_session == nullptr || !hs->new_session->has_application_settings || ssl->s3->early_data_accepted) { return true; } CBB contents; if (!CBB_add_u16(out, TLSEXT_TYPE_application_settings) || !CBB_add_u16_length_prefixed(out, &contents) || !CBB_add_bytes(&contents, hs->new_session->local_application_settings.data(), hs->new_session->local_application_settings.size()) || !CBB_flush(out)) { return false; } return true; } bool ssl_negotiate_alps(SSL_HANDSHAKE *hs, uint8_t *out_alert, const SSL_CLIENT_HELLO *client_hello) { SSL *const ssl = hs->ssl; if (ssl->s3->alpn_selected.empty()) { return true; } // If we negotiate ALPN over TLS 1.3, try to negotiate ALPS. CBS alps_contents; Span<const uint8_t> settings; if (ssl_protocol_version(ssl) >= TLS1_3_VERSION && ssl_get_local_application_settings(hs, &settings, ssl->s3->alpn_selected) && ssl_client_hello_get_extension(client_hello, &alps_contents, TLSEXT_TYPE_application_settings)) { // Check if the client supports ALPS with the selected ALPN. bool found = false; CBS alps_list; if (!CBS_get_u16_length_prefixed(&alps_contents, &alps_list) || CBS_len(&alps_contents) != 0 || CBS_len(&alps_list) == 0) { OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR); *out_alert = SSL_AD_DECODE_ERROR; return false; } while (CBS_len(&alps_list) > 0) { CBS protocol_name; if (!CBS_get_u8_length_prefixed(&alps_list, &protocol_name) || // Empty protocol names are forbidden. CBS_len(&protocol_name) == 0) { OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR); *out_alert = SSL_AD_DECODE_ERROR; return false; } if (protocol_name == MakeConstSpan(ssl->s3->alpn_selected)) { found = true; } } // Negotiate ALPS if both client also supports ALPS for this protocol. if (found) { hs->new_session->has_application_settings = true; if (!hs->new_session->local_application_settings.CopyFrom(settings)) { *out_alert = SSL_AD_INTERNAL_ERROR; return false; } } } return true; } // kExtensions contains all the supported extensions. static const struct tls_extension kExtensions[] = { { TLSEXT_TYPE_server_name, ext_sni_add_clienthello, ext_sni_parse_serverhello, ext_sni_parse_clienthello, ext_sni_add_serverhello, }, { TLSEXT_TYPE_encrypted_client_hello, ext_ech_add_clienthello, ext_ech_parse_serverhello, ext_ech_parse_clienthello, ext_ech_add_serverhello, }, { TLSEXT_TYPE_extended_master_secret, ext_ems_add_clienthello, ext_ems_parse_serverhello, ext_ems_parse_clienthello, ext_ems_add_serverhello, }, { TLSEXT_TYPE_renegotiate, ext_ri_add_clienthello, ext_ri_parse_serverhello, ext_ri_parse_clienthello, ext_ri_add_serverhello, }, { TLSEXT_TYPE_supported_groups, ext_supported_groups_add_clienthello, ext_supported_groups_parse_serverhello, ext_supported_groups_parse_clienthello, dont_add_serverhello, }, { TLSEXT_TYPE_ec_point_formats, ext_ec_point_add_clienthello, ext_ec_point_parse_serverhello, ext_ec_point_parse_clienthello, ext_ec_point_add_serverhello, }, { TLSEXT_TYPE_session_ticket, ext_ticket_add_clienthello, ext_ticket_parse_serverhello, // Ticket extension client parsing is handled in ssl_session.c ignore_parse_clienthello, ext_ticket_add_serverhello, }, { TLSEXT_TYPE_application_layer_protocol_negotiation, ext_alpn_add_clienthello, ext_alpn_parse_serverhello, // ALPN is negotiated late in |ssl_negotiate_alpn|. ignore_parse_clienthello, ext_alpn_add_serverhello, }, { TLSEXT_TYPE_status_request, ext_ocsp_add_clienthello, ext_ocsp_parse_serverhello, ext_ocsp_parse_clienthello, ext_ocsp_add_serverhello, }, { TLSEXT_TYPE_signature_algorithms, ext_sigalgs_add_clienthello, forbid_parse_serverhello, ext_sigalgs_parse_clienthello, dont_add_serverhello, }, { TLSEXT_TYPE_next_proto_neg, ext_npn_add_clienthello, ext_npn_parse_serverhello, ext_npn_parse_clienthello, ext_npn_add_serverhello, }, { TLSEXT_TYPE_certificate_timestamp, ext_sct_add_clienthello, ext_sct_parse_serverhello, ext_sct_parse_clienthello, ext_sct_add_serverhello, }, { TLSEXT_TYPE_channel_id, ext_channel_id_add_clienthello, ext_channel_id_parse_serverhello, ext_channel_id_parse_clienthello, ext_channel_id_add_serverhello, }, { TLSEXT_TYPE_srtp, ext_srtp_add_clienthello, ext_srtp_parse_serverhello, ext_srtp_parse_clienthello, ext_srtp_add_serverhello, }, { TLSEXT_TYPE_key_share, ext_key_share_add_clienthello, forbid_parse_serverhello, ignore_parse_clienthello, dont_add_serverhello, }, { TLSEXT_TYPE_psk_key_exchange_modes, ext_psk_key_exchange_modes_add_clienthello, forbid_parse_serverhello, ext_psk_key_exchange_modes_parse_clienthello, dont_add_serverhello, }, { TLSEXT_TYPE_early_data, ext_early_data_add_clienthello, ext_early_data_parse_serverhello, ext_early_data_parse_clienthello, ext_early_data_add_serverhello, }, { TLSEXT_TYPE_supported_versions, ext_supported_versions_add_clienthello, forbid_parse_serverhello, ignore_parse_clienthello, dont_add_serverhello, }, { TLSEXT_TYPE_cookie, ext_cookie_add_clienthello, forbid_parse_serverhello, ignore_parse_clienthello, dont_add_serverhello, }, { TLSEXT_TYPE_quic_transport_parameters, ext_quic_transport_params_add_clienthello, ext_quic_transport_params_parse_serverhello, ext_quic_transport_params_parse_clienthello, ext_quic_transport_params_add_serverhello, }, { TLSEXT_TYPE_quic_transport_parameters_legacy, ext_quic_transport_params_add_clienthello_legacy, ext_quic_transport_params_parse_serverhello_legacy, ext_quic_transport_params_parse_clienthello_legacy, ext_quic_transport_params_add_serverhello_legacy, }, { TLSEXT_TYPE_cert_compression, cert_compression_add_clienthello, cert_compression_parse_serverhello, cert_compression_parse_clienthello, cert_compression_add_serverhello, }, { TLSEXT_TYPE_delegated_credential, ext_delegated_credential_add_clienthello, forbid_parse_serverhello, ext_delegated_credential_parse_clienthello, dont_add_serverhello, }, { TLSEXT_TYPE_application_settings, ext_alps_add_clienthello, ext_alps_parse_serverhello, // ALPS is negotiated late in |ssl_negotiate_alpn|. ignore_parse_clienthello, ext_alps_add_serverhello, }, }; #define kNumExtensions (sizeof(kExtensions) / sizeof(struct tls_extension)) static_assert(kNumExtensions <= sizeof(((SSL_HANDSHAKE *)NULL)->extensions.sent) * 8, "too many extensions for sent bitset"); static_assert(kNumExtensions <= sizeof(((SSL_HANDSHAKE *)NULL)->extensions.received) * 8, "too many extensions for received bitset"); bool ssl_setup_extension_permutation(SSL_HANDSHAKE *hs) { if (!hs->config->permute_extensions) { return true; } static_assert(kNumExtensions <= UINT8_MAX, "extensions_permutation type is too small"); uint32_t seeds[kNumExtensions - 1]; Array<uint8_t> permutation; if (!RAND_bytes(reinterpret_cast<uint8_t *>(seeds), sizeof(seeds)) || !permutation.Init(kNumExtensions)) { return false; } for (size_t i = 0; i < kNumExtensions; i++) { permutation[i] = i; } for (size_t i = kNumExtensions - 1; i > 0; i--) { // Set element |i| to a randomly-selected element 0 <= j <= i. std::swap(permutation[i], permutation[seeds[i - 1] % (i + 1)]); } hs->extension_permutation = std::move(permutation); return true; } static const struct tls_extension *tls_extension_find(uint32_t *out_index, uint16_t value) { unsigned i; for (i = 0; i < kNumExtensions; i++) { if (kExtensions[i].value == value) { *out_index = i; return &kExtensions[i]; } } return NULL; } static bool add_padding_extension(CBB *cbb, uint16_t ext, size_t len) { CBB child; if (!CBB_add_u16(cbb, ext) || // !CBB_add_u16_length_prefixed(cbb, &child) || !CBB_add_zeros(&child, len)) { OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR); return false; } return CBB_flush(cbb); } static bool ssl_add_clienthello_tlsext_inner(SSL_HANDSHAKE *hs, CBB *out, CBB *out_encoded, bool *out_needs_psk_binder) { // When writing ClientHelloInner, we construct the real and encoded // ClientHellos concurrently, to handle compression. Uncompressed extensions // are written to |extensions| and copied to |extensions_encoded|. Compressed // extensions are buffered in |compressed| and written to the end. (ECH can // only compress continguous extensions.) SSL *const ssl = hs->ssl; bssl::ScopedCBB compressed, outer_extensions; CBB extensions, extensions_encoded; if (!CBB_add_u16_length_prefixed(out, &extensions) || !CBB_add_u16_length_prefixed(out_encoded, &extensions_encoded) || !CBB_init(compressed.get(), 64) || !CBB_init(outer_extensions.get(), 64)) { OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR); return false; } hs->inner_extensions_sent = 0; if (ssl->ctx->grease_enabled) { // Add a fake empty extension. See RFC 8701. This always matches // |ssl_add_clienthello_tlsext|, so compress it. uint16_t grease_ext = ssl_get_grease_value(hs, ssl_grease_extension1); if (!add_padding_extension(compressed.get(), grease_ext, 0) || !CBB_add_u16(outer_extensions.get(), grease_ext)) { return false; } } for (size_t unpermuted = 0; unpermuted < kNumExtensions; unpermuted++) { size_t i = hs->extension_permutation.empty() ? unpermuted : hs->extension_permutation[unpermuted]; const size_t len_before = CBB_len(&extensions); const size_t len_compressed_before = CBB_len(compressed.get()); if (!kExtensions[i].add_clienthello(hs, &extensions, compressed.get(), ssl_client_hello_inner)) { OPENSSL_PUT_ERROR(SSL, SSL_R_ERROR_ADDING_EXTENSION); ERR_add_error_dataf("extension %u", (unsigned)kExtensions[i].value); return false; } const size_t bytes_written = CBB_len(&extensions) - len_before; const size_t bytes_written_compressed = CBB_len(compressed.get()) - len_compressed_before; // The callback may write to at most one output. assert(bytes_written == 0 || bytes_written_compressed == 0); if (bytes_written != 0 || bytes_written_compressed != 0) { hs->inner_extensions_sent |= (1u << i); } // If compressed, update the running ech_outer_extensions extension. if (bytes_written_compressed != 0 && !CBB_add_u16(outer_extensions.get(), kExtensions[i].value)) { return false; } } if (ssl->ctx->grease_enabled) { // Add a fake non-empty extension. See RFC 8701. This always matches // |ssl_add_clienthello_tlsext|, so compress it. uint16_t grease_ext = ssl_get_grease_value(hs, ssl_grease_extension2); if (!add_padding_extension(compressed.get(), grease_ext, 1) || !CBB_add_u16(outer_extensions.get(), grease_ext)) { return false; } } // Uncompressed extensions are encoded as-is. if (!CBB_add_bytes(&extensions_encoded, CBB_data(&extensions), CBB_len(&extensions))) { return false; } // Flush all the compressed extensions. if (CBB_len(compressed.get()) != 0) { CBB extension, child; // Copy them as-is in the real ClientHelloInner. if (!CBB_add_bytes(&extensions, CBB_data(compressed.get()), CBB_len(compressed.get())) || // Replace with ech_outer_extensions in the encoded form. !CBB_add_u16(&extensions_encoded, TLSEXT_TYPE_ech_outer_extensions) || !CBB_add_u16_length_prefixed(&extensions_encoded, &extension) || !CBB_add_u8_length_prefixed(&extension, &child) || !CBB_add_bytes(&child, CBB_data(outer_extensions.get()), CBB_len(outer_extensions.get())) || !CBB_flush(&extensions_encoded)) { return false; } } // The PSK extension must be last. It is never compressed. Note, if there is a // binder, the caller will need to update both ClientHelloInner and // EncodedClientHelloInner after computing it. const size_t len_before = CBB_len(&extensions); if (!ext_pre_shared_key_add_clienthello(hs, &extensions, out_needs_psk_binder, ssl_client_hello_inner) || !CBB_add_bytes(&extensions_encoded, CBB_data(&extensions) + len_before, CBB_len(&extensions) - len_before) || !CBB_flush(out) || // !CBB_flush(out_encoded)) { return false; } return true; } bool ssl_add_clienthello_tlsext(SSL_HANDSHAKE *hs, CBB *out, CBB *out_encoded, bool *out_needs_psk_binder, ssl_client_hello_type_t type, size_t header_len) { *out_needs_psk_binder = false; if (type == ssl_client_hello_inner) { return ssl_add_clienthello_tlsext_inner(hs, out, out_encoded, out_needs_psk_binder); } assert(out_encoded == nullptr); // Only ClientHelloInner needs two outputs. SSL *const ssl = hs->ssl; CBB extensions; if (!CBB_add_u16_length_prefixed(out, &extensions)) { OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR); return false; } // Note we may send multiple ClientHellos for DTLS HelloVerifyRequest and TLS // 1.3 HelloRetryRequest. For the latter, the extensions may change, so it is // important to reset this value. hs->extensions.sent = 0; // Add a fake empty extension. See RFC 8701. if (ssl->ctx->grease_enabled && !add_padding_extension( &extensions, ssl_get_grease_value(hs, ssl_grease_extension1), 0)) { return false; } bool last_was_empty = false; for (size_t unpermuted = 0; unpermuted < kNumExtensions; unpermuted++) { size_t i = hs->extension_permutation.empty() ? unpermuted : hs->extension_permutation[unpermuted]; const size_t len_before = CBB_len(&extensions); if (!kExtensions[i].add_clienthello(hs, &extensions, &extensions, type)) { OPENSSL_PUT_ERROR(SSL, SSL_R_ERROR_ADDING_EXTENSION); ERR_add_error_dataf("extension %u", (unsigned)kExtensions[i].value); return false; } const size_t bytes_written = CBB_len(&extensions) - len_before; if (bytes_written != 0) { hs->extensions.sent |= (1u << i); } // If the difference in lengths is only four bytes then the extension had // an empty body. last_was_empty = (bytes_written == 4); } if (ssl->ctx->grease_enabled) { // Add a fake non-empty extension. See RFC 8701. if (!add_padding_extension( &extensions, ssl_get_grease_value(hs, ssl_grease_extension2), 1)) { return false; } last_was_empty = false; } // In cleartext ClientHellos, we add the padding extension to work around // bugs. We also apply this padding to ClientHelloOuter, to keep the wire // images aligned. size_t psk_extension_len = ext_pre_shared_key_clienthello_length(hs, type); if (!SSL_is_dtls(ssl) && !ssl->quic_method && !ssl->s3->used_hello_retry_request) { header_len += SSL3_HM_HEADER_LENGTH + 2 + CBB_len(&extensions) + psk_extension_len; size_t padding_len = 0; // The final extension must be non-empty. WebSphere Application // Server 7.0 is intolerant to the last extension being zero-length. See // https://crbug.com/363583. if (last_was_empty && psk_extension_len == 0) { padding_len = 1; // The addition of the padding extension may push us into the F5 bug. header_len += 4 + padding_len; } // Add padding to workaround bugs in F5 terminators. See RFC 7685. // // NB: because this code works out the length of all existing extensions // it MUST always appear last (save for any PSK extension). if (header_len > 0xff && header_len < 0x200) { // If our calculations already included a padding extension, remove that // factor because we're about to change its length. if (padding_len != 0) { header_len -= 4 + padding_len; } padding_len = 0x200 - header_len; // Extensions take at least four bytes to encode. Always include at least // one byte of data if including the extension. WebSphere Application // Server 7.0 is intolerant to the last extension being zero-length. See // https://crbug.com/363583. if (padding_len >= 4 + 1) { padding_len -= 4; } else { padding_len = 1; } } if (padding_len != 0 && !add_padding_extension(&extensions, TLSEXT_TYPE_padding, padding_len)) { return false; } } // The PSK extension must be last, including after the padding. const size_t len_before = CBB_len(&extensions); if (!ext_pre_shared_key_add_clienthello(hs, &extensions, out_needs_psk_binder, type)) { OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR); return false; } assert(psk_extension_len == CBB_len(&extensions) - len_before); (void)len_before; // |assert| is omitted in release builds. // Discard empty extensions blocks. if (CBB_len(&extensions) == 0) { CBB_discard_child(out); } return CBB_flush(out); } bool ssl_add_serverhello_tlsext(SSL_HANDSHAKE *hs, CBB *out) { SSL *const ssl = hs->ssl; CBB extensions; if (!CBB_add_u16_length_prefixed(out, &extensions)) { goto err; } for (unsigned i = 0; i < kNumExtensions; i++) { if (!(hs->extensions.received & (1u << i))) { // Don't send extensions that were not received. continue; } if (!kExtensions[i].add_serverhello(hs, &extensions)) { OPENSSL_PUT_ERROR(SSL, SSL_R_ERROR_ADDING_EXTENSION); ERR_add_error_dataf("extension %u", (unsigned)kExtensions[i].value); goto err; } } // Discard empty extensions blocks before TLS 1.3. if (ssl_protocol_version(ssl) < TLS1_3_VERSION && CBB_len(&extensions) == 0) { CBB_discard_child(out); } return CBB_flush(out); err: OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR); return false; } static bool ssl_scan_clienthello_tlsext(SSL_HANDSHAKE *hs, const SSL_CLIENT_HELLO *client_hello, int *out_alert) { hs->extensions.received = 0; CBS extensions; CBS_init(&extensions, client_hello->extensions, client_hello->extensions_len); while (CBS_len(&extensions) != 0) { uint16_t type; CBS extension; // Decode the next extension. if (!CBS_get_u16(&extensions, &type) || !CBS_get_u16_length_prefixed(&extensions, &extension)) { *out_alert = SSL_AD_DECODE_ERROR; return false; } unsigned ext_index; const struct tls_extension *const ext = tls_extension_find(&ext_index, type); if (ext == NULL) { continue; } hs->extensions.received |= (1u << ext_index); uint8_t alert = SSL_AD_DECODE_ERROR; if (!ext->parse_clienthello(hs, &alert, &extension)) { *out_alert = alert; OPENSSL_PUT_ERROR(SSL, SSL_R_ERROR_PARSING_EXTENSION); ERR_add_error_dataf("extension %u", (unsigned)type); return false; } } for (size_t i = 0; i < kNumExtensions; i++) { if (hs->extensions.received & (1u << i)) { continue; } CBS *contents = NULL, fake_contents; static const uint8_t kFakeRenegotiateExtension[] = {0}; if (kExtensions[i].value == TLSEXT_TYPE_renegotiate && ssl_client_cipher_list_contains_cipher(client_hello, SSL3_CK_SCSV & 0xffff)) { // The renegotiation SCSV was received so pretend that we received a // renegotiation extension. CBS_init(&fake_contents, kFakeRenegotiateExtension, sizeof(kFakeRenegotiateExtension)); contents = &fake_contents; hs->extensions.received |= (1u << i); } // Extension wasn't observed so call the callback with a NULL // parameter. uint8_t alert = SSL_AD_DECODE_ERROR; if (!kExtensions[i].parse_clienthello(hs, &alert, contents)) { OPENSSL_PUT_ERROR(SSL, SSL_R_MISSING_EXTENSION); ERR_add_error_dataf("extension %u", (unsigned)kExtensions[i].value); *out_alert = alert; return false; } } return true; } bool ssl_parse_clienthello_tlsext(SSL_HANDSHAKE *hs, const SSL_CLIENT_HELLO *client_hello) { SSL *const ssl = hs->ssl; int alert = SSL_AD_DECODE_ERROR; if (!ssl_scan_clienthello_tlsext(hs, client_hello, &alert)) { ssl_send_alert(ssl, SSL3_AL_FATAL, alert); return false; } if (!ssl_check_clienthello_tlsext(hs)) { OPENSSL_PUT_ERROR(SSL, SSL_R_CLIENTHELLO_TLSEXT); return false; } return true; } static bool ssl_scan_serverhello_tlsext(SSL_HANDSHAKE *hs, const CBS *cbs, int *out_alert) { CBS extensions = *cbs; if (!tls1_check_duplicate_extensions(&extensions)) { *out_alert = SSL_AD_DECODE_ERROR; return false; } uint32_t received = 0; while (CBS_len(&extensions) != 0) { uint16_t type; CBS extension; // Decode the next extension. if (!CBS_get_u16(&extensions, &type) || !CBS_get_u16_length_prefixed(&extensions, &extension)) { *out_alert = SSL_AD_DECODE_ERROR; return false; } unsigned ext_index; const struct tls_extension *const ext = tls_extension_find(&ext_index, type); if (ext == NULL) { OPENSSL_PUT_ERROR(SSL, SSL_R_UNEXPECTED_EXTENSION); ERR_add_error_dataf("extension %u", (unsigned)type); *out_alert = SSL_AD_UNSUPPORTED_EXTENSION; return false; } static_assert(kNumExtensions <= sizeof(hs->extensions.sent) * 8, "too many bits"); if (!(hs->extensions.sent & (1u << ext_index))) { // If the extension was never sent then it is illegal. OPENSSL_PUT_ERROR(SSL, SSL_R_UNEXPECTED_EXTENSION); ERR_add_error_dataf("extension :%u", (unsigned)type); *out_alert = SSL_AD_UNSUPPORTED_EXTENSION; return false; } received |= (1u << ext_index); uint8_t alert = SSL_AD_DECODE_ERROR; if (!ext->parse_serverhello(hs, &alert, &extension)) { OPENSSL_PUT_ERROR(SSL, SSL_R_ERROR_PARSING_EXTENSION); ERR_add_error_dataf("extension %u", (unsigned)type); *out_alert = alert; return false; } } for (size_t i = 0; i < kNumExtensions; i++) { if (!(received & (1u << i))) { // Extension wasn't observed so call the callback with a NULL // parameter. uint8_t alert = SSL_AD_DECODE_ERROR; if (!kExtensions[i].parse_serverhello(hs, &alert, NULL)) { OPENSSL_PUT_ERROR(SSL, SSL_R_MISSING_EXTENSION); ERR_add_error_dataf("extension %u", (unsigned)kExtensions[i].value); *out_alert = alert; return false; } } } return true; } static bool ssl_check_clienthello_tlsext(SSL_HANDSHAKE *hs) { SSL *const ssl = hs->ssl; int ret = SSL_TLSEXT_ERR_NOACK; int al = SSL_AD_UNRECOGNIZED_NAME; if (ssl->ctx->servername_callback != 0) { ret = ssl->ctx->servername_callback(ssl, &al, ssl->ctx->servername_arg); } else if (ssl->session_ctx->servername_callback != 0) { ret = ssl->session_ctx->servername_callback( ssl, &al, ssl->session_ctx->servername_arg); } switch (ret) { case SSL_TLSEXT_ERR_ALERT_FATAL: ssl_send_alert(ssl, SSL3_AL_FATAL, al); return false; case SSL_TLSEXT_ERR_NOACK: hs->should_ack_sni = false; return true; default: return true; } } static bool ssl_check_serverhello_tlsext(SSL_HANDSHAKE *hs) { SSL *const ssl = hs->ssl; // ALPS and ALPN have a dependency between each other, so we defer checking // consistency to after the callbacks run. if (hs->new_session != nullptr && hs->new_session->has_application_settings) { // ALPN must be negotiated. if (ssl->s3->alpn_selected.empty()) { OPENSSL_PUT_ERROR(SSL, SSL_R_NEGOTIATED_ALPS_WITHOUT_ALPN); ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_ILLEGAL_PARAMETER); return false; } // The negotiated protocol must be one of the ones we advertised for ALPS. Span<const uint8_t> settings; if (!ssl_get_local_application_settings(hs, &settings, ssl->s3->alpn_selected)) { OPENSSL_PUT_ERROR(SSL, SSL_R_INVALID_ALPN_PROTOCOL); ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_ILLEGAL_PARAMETER); return false; } if (!hs->new_session->local_application_settings.CopyFrom(settings)) { ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR); return false; } } return true; } bool ssl_parse_serverhello_tlsext(SSL_HANDSHAKE *hs, const CBS *cbs) { SSL *const ssl = hs->ssl; int alert = SSL_AD_DECODE_ERROR; if (!ssl_scan_serverhello_tlsext(hs, cbs, &alert)) { ssl_send_alert(ssl, SSL3_AL_FATAL, alert); return false; } if (!ssl_check_serverhello_tlsext(hs)) { return false; } return true; } static enum ssl_ticket_aead_result_t decrypt_ticket_with_cipher_ctx( Array<uint8_t> *out, EVP_CIPHER_CTX *cipher_ctx, HMAC_CTX *hmac_ctx, Span<const uint8_t> ticket) { size_t iv_len = EVP_CIPHER_CTX_iv_length(cipher_ctx); // Check the MAC at the end of the ticket. uint8_t mac[EVP_MAX_MD_SIZE]; size_t mac_len = HMAC_size(hmac_ctx); if (ticket.size() < SSL_TICKET_KEY_NAME_LEN + iv_len + 1 + mac_len) { // The ticket must be large enough for key name, IV, data, and MAC. return ssl_ticket_aead_ignore_ticket; } // Split the ticket into the ticket and the MAC. auto ticket_mac = ticket.last(mac_len); ticket = ticket.first(ticket.size() - mac_len); HMAC_Update(hmac_ctx, ticket.data(), ticket.size()); HMAC_Final(hmac_ctx, mac, NULL); assert(mac_len == ticket_mac.size()); bool mac_ok = CRYPTO_memcmp(mac, ticket_mac.data(), mac_len) == 0; #if defined(BORINGSSL_UNSAFE_FUZZER_MODE) mac_ok = true; #endif if (!mac_ok) { return ssl_ticket_aead_ignore_ticket; } // Decrypt the session data. auto ciphertext = ticket.subspan(SSL_TICKET_KEY_NAME_LEN + iv_len); Array<uint8_t> plaintext; #if defined(BORINGSSL_UNSAFE_FUZZER_MODE) if (!plaintext.CopyFrom(ciphertext)) { return ssl_ticket_aead_error; } #else if (ciphertext.size() >= INT_MAX) { return ssl_ticket_aead_ignore_ticket; } if (!plaintext.Init(ciphertext.size())) { return ssl_ticket_aead_error; } int len1, len2; if (!EVP_DecryptUpdate(cipher_ctx, plaintext.data(), &len1, ciphertext.data(), (int)ciphertext.size()) || !EVP_DecryptFinal_ex(cipher_ctx, plaintext.data() + len1, &len2)) { ERR_clear_error(); return ssl_ticket_aead_ignore_ticket; } plaintext.Shrink(static_cast<size_t>(len1) + len2); #endif *out = std::move(plaintext); return ssl_ticket_aead_success; } static enum ssl_ticket_aead_result_t ssl_decrypt_ticket_with_cb( SSL_HANDSHAKE *hs, Array<uint8_t> *out, bool *out_renew_ticket, Span<const uint8_t> ticket) { assert(ticket.size() >= SSL_TICKET_KEY_NAME_LEN + EVP_MAX_IV_LENGTH); ScopedEVP_CIPHER_CTX cipher_ctx; ScopedHMAC_CTX hmac_ctx; auto name = ticket.subspan(0, SSL_TICKET_KEY_NAME_LEN); // The actual IV is shorter, but the length is determined by the callback's // chosen cipher. Instead we pass in |EVP_MAX_IV_LENGTH| worth of IV to ensure // the callback has enough. auto iv = ticket.subspan(SSL_TICKET_KEY_NAME_LEN, EVP_MAX_IV_LENGTH); int cb_ret = hs->ssl->session_ctx->ticket_key_cb( hs->ssl, const_cast<uint8_t *>(name.data()), const_cast<uint8_t *>(iv.data()), cipher_ctx.get(), hmac_ctx.get(), 0 /* decrypt */); if (cb_ret < 0) { return ssl_ticket_aead_error; } else if (cb_ret == 0) { return ssl_ticket_aead_ignore_ticket; } else if (cb_ret == 2) { *out_renew_ticket = true; } else { assert(cb_ret == 1); } return decrypt_ticket_with_cipher_ctx(out, cipher_ctx.get(), hmac_ctx.get(), ticket); } static enum ssl_ticket_aead_result_t ssl_decrypt_ticket_with_ticket_keys( SSL_HANDSHAKE *hs, Array<uint8_t> *out, Span<const uint8_t> ticket) { assert(ticket.size() >= SSL_TICKET_KEY_NAME_LEN + EVP_MAX_IV_LENGTH); SSL_CTX *ctx = hs->ssl->session_ctx.get(); // Rotate the ticket key if necessary. if (!ssl_ctx_rotate_ticket_encryption_key(ctx)) { return ssl_ticket_aead_error; } const EVP_CIPHER *cipher = EVP_aes_128_cbc(); auto name = ticket.subspan(0, SSL_TICKET_KEY_NAME_LEN); auto iv = ticket.subspan(SSL_TICKET_KEY_NAME_LEN, EVP_CIPHER_iv_length(cipher)); // Pick the matching ticket key and decrypt. ScopedEVP_CIPHER_CTX cipher_ctx; ScopedHMAC_CTX hmac_ctx; { MutexReadLock lock(&ctx->lock); const TicketKey *key; if (ctx->ticket_key_current && name == ctx->ticket_key_current->name) { key = ctx->ticket_key_current.get(); } else if (ctx->ticket_key_prev && name == ctx->ticket_key_prev->name) { key = ctx->ticket_key_prev.get(); } else { return ssl_ticket_aead_ignore_ticket; } if (!HMAC_Init_ex(hmac_ctx.get(), key->hmac_key, sizeof(key->hmac_key), tlsext_tick_md(), NULL) || !EVP_DecryptInit_ex(cipher_ctx.get(), cipher, NULL, key->aes_key, iv.data())) { return ssl_ticket_aead_error; } } return decrypt_ticket_with_cipher_ctx(out, cipher_ctx.get(), hmac_ctx.get(), ticket); } static enum ssl_ticket_aead_result_t ssl_decrypt_ticket_with_method( SSL_HANDSHAKE *hs, Array<uint8_t> *out, bool *out_renew_ticket, Span<const uint8_t> ticket) { Array<uint8_t> plaintext; if (!plaintext.Init(ticket.size())) { OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE); return ssl_ticket_aead_error; } size_t plaintext_len; const enum ssl_ticket_aead_result_t result = hs->ssl->session_ctx->ticket_aead_method->open( hs->ssl, plaintext.data(), &plaintext_len, ticket.size(), ticket.data(), ticket.size()); if (result != ssl_ticket_aead_success) { return result; } plaintext.Shrink(plaintext_len); *out = std::move(plaintext); return ssl_ticket_aead_success; } enum ssl_ticket_aead_result_t ssl_process_ticket( SSL_HANDSHAKE *hs, UniquePtr<SSL_SESSION> *out_session, bool *out_renew_ticket, Span<const uint8_t> ticket, Span<const uint8_t> session_id) { SSL *const ssl = hs->ssl; *out_renew_ticket = false; out_session->reset(); if ((SSL_get_options(hs->ssl) & SSL_OP_NO_TICKET) || session_id.size() > SSL_MAX_SSL_SESSION_ID_LENGTH) { return ssl_ticket_aead_ignore_ticket; } // Tickets in TLS 1.3 are tied into pre-shared keys (PSKs), unlike in TLS 1.2 // where that concept doesn't exist. The |decrypted_psk| and |ignore_psk| // hints only apply to PSKs. We check the version to determine which this is. const bool is_psk = ssl_protocol_version(ssl) >= TLS1_3_VERSION; Array<uint8_t> plaintext; enum ssl_ticket_aead_result_t result; SSL_HANDSHAKE_HINTS *const hints = hs->hints.get(); if (is_psk && hints && !hs->hints_requested && !hints->decrypted_psk.empty()) { result = plaintext.CopyFrom(hints->decrypted_psk) ? ssl_ticket_aead_success : ssl_ticket_aead_error; } else if (is_psk && hints && !hs->hints_requested && hints->ignore_psk) { result = ssl_ticket_aead_ignore_ticket; } else if (ssl->session_ctx->ticket_aead_method != NULL) { result = ssl_decrypt_ticket_with_method(hs, &plaintext, out_renew_ticket, ticket); } else { // Ensure there is room for the key name and the largest IV |ticket_key_cb| // may try to consume. The real limit may be lower, but the maximum IV // length should be well under the minimum size for the session material and // HMAC. if (ticket.size() < SSL_TICKET_KEY_NAME_LEN + EVP_MAX_IV_LENGTH) { result = ssl_ticket_aead_ignore_ticket; } else if (ssl->session_ctx->ticket_key_cb != NULL) { result = ssl_decrypt_ticket_with_cb(hs, &plaintext, out_renew_ticket, ticket); } else { result = ssl_decrypt_ticket_with_ticket_keys(hs, &plaintext, ticket); } } if (is_psk && hints && hs->hints_requested) { if (result == ssl_ticket_aead_ignore_ticket) { hints->ignore_psk = true; } else if (result == ssl_ticket_aead_success && !hints->decrypted_psk.CopyFrom(plaintext)) { return ssl_ticket_aead_error; } } if (result != ssl_ticket_aead_success) { return result; } // Decode the session. UniquePtr<SSL_SESSION> session(SSL_SESSION_from_bytes( plaintext.data(), plaintext.size(), ssl->ctx.get())); if (!session) { ERR_clear_error(); // Don't leave an error on the queue. return ssl_ticket_aead_ignore_ticket; } // Envoy's tests expect the session to have a session ID that matches the // placeholder used by the client. It's unclear whether this is a good idea, // but we maintain it for now. SHA256(ticket.data(), ticket.size(), session->session_id); // Other consumers may expect a non-empty session ID to indicate resumption. session->session_id_length = SHA256_DIGEST_LENGTH; *out_session = std::move(session); return ssl_ticket_aead_success; } bool tls1_parse_peer_sigalgs(SSL_HANDSHAKE *hs, const CBS *in_sigalgs) { // Extension ignored for inappropriate versions if (ssl_protocol_version(hs->ssl) < TLS1_2_VERSION) { return true; } // In all contexts, the signature algorithms list may not be empty. (It may be // omitted by clients in TLS 1.2, but then the entire extension is omitted.) return CBS_len(in_sigalgs) != 0 && parse_u16_array(in_sigalgs, &hs->peer_sigalgs); } bool tls1_get_legacy_signature_algorithm(uint16_t *out, const EVP_PKEY *pkey) { switch (EVP_PKEY_id(pkey)) { case EVP_PKEY_RSA: *out = SSL_SIGN_RSA_PKCS1_MD5_SHA1; return true; case EVP_PKEY_EC: *out = SSL_SIGN_ECDSA_SHA1; return true; default: return false; } } bool tls1_choose_signature_algorithm(SSL_HANDSHAKE *hs, uint16_t *out) { SSL *const ssl = hs->ssl; CERT *cert = hs->config->cert.get(); DC *dc = cert->dc.get(); // Before TLS 1.2, the signature algorithm isn't negotiated as part of the // handshake. if (ssl_protocol_version(ssl) < TLS1_2_VERSION) { if (!tls1_get_legacy_signature_algorithm(out, hs->local_pubkey.get())) { OPENSSL_PUT_ERROR(SSL, SSL_R_NO_COMMON_SIGNATURE_ALGORITHMS); return false; } return true; } Span<const uint16_t> sigalgs = kSignSignatureAlgorithms; if (ssl_signing_with_dc(hs)) { sigalgs = MakeConstSpan(&dc->expected_cert_verify_algorithm, 1); } else if (!cert->sigalgs.empty()) { sigalgs = cert->sigalgs; } Span<const uint16_t> peer_sigalgs = tls1_get_peer_verify_algorithms(hs); for (uint16_t sigalg : sigalgs) { // SSL_SIGN_RSA_PKCS1_MD5_SHA1 is an internal value and should never be // negotiated. if (sigalg == SSL_SIGN_RSA_PKCS1_MD5_SHA1 || !ssl_private_key_supports_signature_algorithm(hs, sigalg)) { continue; } for (uint16_t peer_sigalg : peer_sigalgs) { if (sigalg == peer_sigalg) { *out = sigalg; return true; } } } OPENSSL_PUT_ERROR(SSL, SSL_R_NO_COMMON_SIGNATURE_ALGORITHMS); return false; } Span<const uint16_t> tls1_get_peer_verify_algorithms(const SSL_HANDSHAKE *hs) { Span<const uint16_t> peer_sigalgs = hs->peer_sigalgs; if (peer_sigalgs.empty() && ssl_protocol_version(hs->ssl) < TLS1_3_VERSION) { // If the client didn't specify any signature_algorithms extension then // we can assume that it supports SHA1. See // http://tools.ietf.org/html/rfc5246#section-7.4.1.4.1 static const uint16_t kDefaultPeerAlgorithms[] = {SSL_SIGN_RSA_PKCS1_SHA1, SSL_SIGN_ECDSA_SHA1}; peer_sigalgs = kDefaultPeerAlgorithms; } return peer_sigalgs; } bool tls1_verify_channel_id(SSL_HANDSHAKE *hs, const SSLMessage &msg) { SSL *const ssl = hs->ssl; // A Channel ID handshake message is structured to contain multiple // extensions, but the only one that can be present is Channel ID. uint16_t extension_type; CBS channel_id = msg.body, extension; if (!CBS_get_u16(&channel_id, &extension_type) || !CBS_get_u16_length_prefixed(&channel_id, &extension) || CBS_len(&channel_id) != 0 || extension_type != TLSEXT_TYPE_channel_id || CBS_len(&extension) != TLSEXT_CHANNEL_ID_SIZE) { OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR); ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR); return false; } UniquePtr<EC_GROUP> p256(EC_GROUP_new_by_curve_name(NID_X9_62_prime256v1)); if (!p256) { OPENSSL_PUT_ERROR(SSL, SSL_R_NO_P256_SUPPORT); return false; } UniquePtr<ECDSA_SIG> sig(ECDSA_SIG_new()); UniquePtr<BIGNUM> x(BN_new()), y(BN_new()); if (!sig || !x || !y) { return false; } const uint8_t *p = CBS_data(&extension); if (BN_bin2bn(p + 0, 32, x.get()) == NULL || BN_bin2bn(p + 32, 32, y.get()) == NULL || BN_bin2bn(p + 64, 32, sig->r) == NULL || BN_bin2bn(p + 96, 32, sig->s) == NULL) { return false; } UniquePtr<EC_KEY> key(EC_KEY_new()); UniquePtr<EC_POINT> point(EC_POINT_new(p256.get())); if (!key || !point || !EC_POINT_set_affine_coordinates_GFp(p256.get(), point.get(), x.get(), y.get(), nullptr) || !EC_KEY_set_group(key.get(), p256.get()) || !EC_KEY_set_public_key(key.get(), point.get())) { return false; } uint8_t digest[EVP_MAX_MD_SIZE]; size_t digest_len; if (!tls1_channel_id_hash(hs, digest, &digest_len)) { return false; } bool sig_ok = ECDSA_do_verify(digest, digest_len, sig.get(), key.get()); #if defined(BORINGSSL_UNSAFE_FUZZER_MODE) sig_ok = true; ERR_clear_error(); #endif if (!sig_ok) { OPENSSL_PUT_ERROR(SSL, SSL_R_CHANNEL_ID_SIGNATURE_INVALID); ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECRYPT_ERROR); return false; } OPENSSL_memcpy(ssl->s3->channel_id, p, 64); ssl->s3->channel_id_valid = true; return true; } bool tls1_write_channel_id(SSL_HANDSHAKE *hs, CBB *cbb) { uint8_t digest[EVP_MAX_MD_SIZE]; size_t digest_len; if (!tls1_channel_id_hash(hs, digest, &digest_len)) { return false; } EC_KEY *ec_key = EVP_PKEY_get0_EC_KEY(hs->config->channel_id_private.get()); if (ec_key == nullptr) { OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR); return false; } UniquePtr<BIGNUM> x(BN_new()), y(BN_new()); if (!x || !y || !EC_POINT_get_affine_coordinates_GFp(EC_KEY_get0_group(ec_key), EC_KEY_get0_public_key(ec_key), x.get(), y.get(), nullptr)) { return false; } UniquePtr<ECDSA_SIG> sig(ECDSA_do_sign(digest, digest_len, ec_key)); if (!sig) { return false; } CBB child; if (!CBB_add_u16(cbb, TLSEXT_TYPE_channel_id) || !CBB_add_u16_length_prefixed(cbb, &child) || !BN_bn2cbb_padded(&child, 32, x.get()) || !BN_bn2cbb_padded(&child, 32, y.get()) || !BN_bn2cbb_padded(&child, 32, sig->r) || !BN_bn2cbb_padded(&child, 32, sig->s) || !CBB_flush(cbb)) { return false; } return true; } bool tls1_channel_id_hash(SSL_HANDSHAKE *hs, uint8_t *out, size_t *out_len) { SSL *const ssl = hs->ssl; if (ssl_protocol_version(ssl) >= TLS1_3_VERSION) { Array<uint8_t> msg; if (!tls13_get_cert_verify_signature_input(hs, &msg, ssl_cert_verify_channel_id)) { return false; } SHA256(msg.data(), msg.size(), out); *out_len = SHA256_DIGEST_LENGTH; return true; } SHA256_CTX ctx; SHA256_Init(&ctx); static const char kClientIDMagic[] = "TLS Channel ID signature"; SHA256_Update(&ctx, kClientIDMagic, sizeof(kClientIDMagic)); if (ssl->session != NULL) { static const char kResumptionMagic[] = "Resumption"; SHA256_Update(&ctx, kResumptionMagic, sizeof(kResumptionMagic)); if (ssl->session->original_handshake_hash_len == 0) { OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR); return false; } SHA256_Update(&ctx, ssl->session->original_handshake_hash, ssl->session->original_handshake_hash_len); } uint8_t hs_hash[EVP_MAX_MD_SIZE]; size_t hs_hash_len; if (!hs->transcript.GetHash(hs_hash, &hs_hash_len)) { return false; } SHA256_Update(&ctx, hs_hash, (size_t)hs_hash_len); SHA256_Final(out, &ctx); *out_len = SHA256_DIGEST_LENGTH; return true; } bool tls1_record_handshake_hashes_for_channel_id(SSL_HANDSHAKE *hs) { SSL *const ssl = hs->ssl; // This function should never be called for a resumed session because the // handshake hashes that we wish to record are for the original, full // handshake. if (ssl->session != NULL) { return false; } static_assert( sizeof(hs->new_session->original_handshake_hash) == EVP_MAX_MD_SIZE, "original_handshake_hash is too small"); size_t digest_len; if (!hs->transcript.GetHash(hs->new_session->original_handshake_hash, &digest_len)) { return false; } static_assert(EVP_MAX_MD_SIZE <= 0xff, "EVP_MAX_MD_SIZE does not fit in uint8_t"); hs->new_session->original_handshake_hash_len = (uint8_t)digest_len; return true; } bool ssl_is_sct_list_valid(const CBS *contents) { // Shallow parse the SCT list for sanity. By the RFC // (https://tools.ietf.org/html/rfc6962#section-3.3) neither the list nor any // of the SCTs may be empty. CBS copy = *contents; CBS sct_list; if (!CBS_get_u16_length_prefixed(©, &sct_list) || CBS_len(©) != 0 || CBS_len(&sct_list) == 0) { return false; } while (CBS_len(&sct_list) > 0) { CBS sct; if (!CBS_get_u16_length_prefixed(&sct_list, &sct) || CBS_len(&sct) == 0) { return false; } } return true; } BSSL_NAMESPACE_END using namespace bssl; int SSL_early_callback_ctx_extension_get(const SSL_CLIENT_HELLO *client_hello, uint16_t extension_type, const uint8_t **out_data, size_t *out_len) { CBS cbs; if (!ssl_client_hello_get_extension(client_hello, &cbs, extension_type)) { return 0; } *out_data = CBS_data(&cbs); *out_len = CBS_len(&cbs); return 1; }