/* 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) 1998-2002 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). */ /* ==================================================================== * Copyright 2002 Sun Microsystems, Inc. ALL RIGHTS RESERVED. * ECC cipher suite support in OpenSSL originally developed by * SUN MICROSYSTEMS, INC., and contributed to the OpenSSL project. */ #include <openssl_grpc/ssl.h> #include <assert.h> #include <limits.h> #include <string.h> #include <tuple> #include <openssl_grpc/buf.h> #include <openssl_grpc/bytestring.h> #include <openssl_grpc/err.h> #include <openssl_grpc/evp.h> #include <openssl_grpc/mem.h> #include <openssl_grpc/md5.h> #include <openssl_grpc/nid.h> #include <openssl_grpc/rand.h> #include <openssl_grpc/sha.h> #include "../crypto/internal.h" #include "internal.h" BSSL_NAMESPACE_BEGIN static bool add_record_to_flight(SSL *ssl, uint8_t type, Span<const uint8_t> in) { // The caller should have flushed |pending_hs_data| first. assert(!ssl->s3->pending_hs_data); // We'll never add a flight while in the process of writing it out. assert(ssl->s3->pending_flight_offset == 0); if (ssl->s3->pending_flight == nullptr) { ssl->s3->pending_flight.reset(BUF_MEM_new()); if (ssl->s3->pending_flight == nullptr) { return false; } } size_t max_out = in.size() + SSL_max_seal_overhead(ssl); size_t new_cap = ssl->s3->pending_flight->length + max_out; if (max_out < in.size() || new_cap < max_out) { OPENSSL_PUT_ERROR(SSL, ERR_R_OVERFLOW); return false; } size_t len; if (!BUF_MEM_reserve(ssl->s3->pending_flight.get(), new_cap) || !tls_seal_record(ssl, (uint8_t *)ssl->s3->pending_flight->data + ssl->s3->pending_flight->length, &len, max_out, type, in.data(), in.size())) { return false; } ssl->s3->pending_flight->length += len; return true; } bool tls_init_message(const SSL *ssl, CBB *cbb, CBB *body, uint8_t type) { // Pick a modest size hint to save most of the |realloc| calls. if (!CBB_init(cbb, 64) || !CBB_add_u8(cbb, type) || !CBB_add_u24_length_prefixed(cbb, body)) { OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR); CBB_cleanup(cbb); return false; } return true; } bool tls_finish_message(const SSL *ssl, CBB *cbb, Array<uint8_t> *out_msg) { return CBBFinishArray(cbb, out_msg); } bool tls_add_message(SSL *ssl, Array<uint8_t> msg) { // Pack handshake data into the minimal number of records. This avoids // unnecessary encryption overhead, notably in TLS 1.3 where we send several // encrypted messages in a row. For now, we do not do this for the null // cipher. The benefit is smaller and there is a risk of breaking buggy // implementations. // // TODO(davidben): See if we can do this uniformly. Span<const uint8_t> rest = msg; if (ssl->quic_method == nullptr && ssl->s3->aead_write_ctx->is_null_cipher()) { while (!rest.empty()) { Span<const uint8_t> chunk = rest.subspan(0, ssl->max_send_fragment); rest = rest.subspan(chunk.size()); if (!add_record_to_flight(ssl, SSL3_RT_HANDSHAKE, chunk)) { return false; } } } else { while (!rest.empty()) { // Flush if |pending_hs_data| is full. if (ssl->s3->pending_hs_data && ssl->s3->pending_hs_data->length >= ssl->max_send_fragment && !tls_flush_pending_hs_data(ssl)) { return false; } size_t pending_len = ssl->s3->pending_hs_data ? ssl->s3->pending_hs_data->length : 0; Span<const uint8_t> chunk = rest.subspan(0, ssl->max_send_fragment - pending_len); assert(!chunk.empty()); rest = rest.subspan(chunk.size()); if (!ssl->s3->pending_hs_data) { ssl->s3->pending_hs_data.reset(BUF_MEM_new()); } if (!ssl->s3->pending_hs_data || !BUF_MEM_append(ssl->s3->pending_hs_data.get(), chunk.data(), chunk.size())) { return false; } } } ssl_do_msg_callback(ssl, 1 /* write */, SSL3_RT_HANDSHAKE, msg); // TODO(svaldez): Move this up a layer to fix abstraction for SSLTranscript on // hs. if (ssl->s3->hs != NULL && !ssl->s3->hs->transcript.Update(msg)) { return false; } return true; } bool tls_flush_pending_hs_data(SSL *ssl) { if (!ssl->s3->pending_hs_data || ssl->s3->pending_hs_data->length == 0) { return true; } UniquePtr<BUF_MEM> pending_hs_data = std::move(ssl->s3->pending_hs_data); auto data = MakeConstSpan(reinterpret_cast<const uint8_t *>(pending_hs_data->data), pending_hs_data->length); if (ssl->quic_method) { if ((ssl->s3->hs == nullptr || !ssl->s3->hs->hints_requested) && !ssl->quic_method->add_handshake_data(ssl, ssl->s3->write_level, data.data(), data.size())) { OPENSSL_PUT_ERROR(SSL, SSL_R_QUIC_INTERNAL_ERROR); return false; } return true; } return add_record_to_flight(ssl, SSL3_RT_HANDSHAKE, data); } bool tls_add_change_cipher_spec(SSL *ssl) { static const uint8_t kChangeCipherSpec[1] = {SSL3_MT_CCS}; if (!tls_flush_pending_hs_data(ssl)) { return false; } if (!ssl->quic_method && !add_record_to_flight(ssl, SSL3_RT_CHANGE_CIPHER_SPEC, kChangeCipherSpec)) { return false; } ssl_do_msg_callback(ssl, 1 /* write */, SSL3_RT_CHANGE_CIPHER_SPEC, kChangeCipherSpec); return true; } int tls_flush_flight(SSL *ssl) { if (!tls_flush_pending_hs_data(ssl)) { return -1; } if (ssl->quic_method) { if (ssl->s3->write_shutdown != ssl_shutdown_none) { OPENSSL_PUT_ERROR(SSL, SSL_R_PROTOCOL_IS_SHUTDOWN); return -1; } if (!ssl->quic_method->flush_flight(ssl)) { OPENSSL_PUT_ERROR(SSL, SSL_R_QUIC_INTERNAL_ERROR); return -1; } } if (ssl->s3->pending_flight == nullptr) { return 1; } if (ssl->s3->write_shutdown != ssl_shutdown_none) { OPENSSL_PUT_ERROR(SSL, SSL_R_PROTOCOL_IS_SHUTDOWN); return -1; } static_assert(INT_MAX <= 0xffffffff, "int is larger than 32 bits"); if (ssl->s3->pending_flight->length > INT_MAX) { OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR); return -1; } // If there is pending data in the write buffer, it must be flushed out before // any new data in pending_flight. if (!ssl->s3->write_buffer.empty()) { int ret = ssl_write_buffer_flush(ssl); if (ret <= 0) { ssl->s3->rwstate = SSL_ERROR_WANT_WRITE; return ret; } } if (ssl->wbio == nullptr) { OPENSSL_PUT_ERROR(SSL, SSL_R_BIO_NOT_SET); return -1; } // Write the pending flight. while (ssl->s3->pending_flight_offset < ssl->s3->pending_flight->length) { int ret = BIO_write( ssl->wbio.get(), ssl->s3->pending_flight->data + ssl->s3->pending_flight_offset, ssl->s3->pending_flight->length - ssl->s3->pending_flight_offset); if (ret <= 0) { ssl->s3->rwstate = SSL_ERROR_WANT_WRITE; return ret; } ssl->s3->pending_flight_offset += ret; } if (BIO_flush(ssl->wbio.get()) <= 0) { ssl->s3->rwstate = SSL_ERROR_WANT_WRITE; return -1; } ssl->s3->pending_flight.reset(); ssl->s3->pending_flight_offset = 0; return 1; } static ssl_open_record_t read_v2_client_hello(SSL *ssl, size_t *out_consumed, Span<const uint8_t> in) { *out_consumed = 0; assert(in.size() >= SSL3_RT_HEADER_LENGTH); // Determine the length of the V2ClientHello. size_t msg_length = ((in[0] & 0x7f) << 8) | in[1]; if (msg_length > (1024 * 4)) { OPENSSL_PUT_ERROR(SSL, SSL_R_RECORD_TOO_LARGE); return ssl_open_record_error; } if (msg_length < SSL3_RT_HEADER_LENGTH - 2) { // Reject lengths that are too short early. We have already read // |SSL3_RT_HEADER_LENGTH| bytes, so we should not attempt to process an // (invalid) V2ClientHello which would be shorter than that. OPENSSL_PUT_ERROR(SSL, SSL_R_RECORD_LENGTH_MISMATCH); return ssl_open_record_error; } // Ask for the remainder of the V2ClientHello. if (in.size() < 2 + msg_length) { *out_consumed = 2 + msg_length; return ssl_open_record_partial; } CBS v2_client_hello = CBS(ssl->s3->read_buffer.span().subspan(2, msg_length)); // The V2ClientHello without the length is incorporated into the handshake // hash. This is only ever called at the start of the handshake, so hs is // guaranteed to be non-NULL. if (!ssl->s3->hs->transcript.Update(v2_client_hello)) { return ssl_open_record_error; } ssl_do_msg_callback(ssl, 0 /* read */, 0 /* V2ClientHello */, v2_client_hello); uint8_t msg_type; uint16_t version, cipher_spec_length, session_id_length, challenge_length; CBS cipher_specs, session_id, challenge; if (!CBS_get_u8(&v2_client_hello, &msg_type) || !CBS_get_u16(&v2_client_hello, &version) || !CBS_get_u16(&v2_client_hello, &cipher_spec_length) || !CBS_get_u16(&v2_client_hello, &session_id_length) || !CBS_get_u16(&v2_client_hello, &challenge_length) || !CBS_get_bytes(&v2_client_hello, &cipher_specs, cipher_spec_length) || !CBS_get_bytes(&v2_client_hello, &session_id, session_id_length) || !CBS_get_bytes(&v2_client_hello, &challenge, challenge_length) || CBS_len(&v2_client_hello) != 0) { OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR); return ssl_open_record_error; } // msg_type has already been checked. assert(msg_type == SSL2_MT_CLIENT_HELLO); // The client_random is the V2ClientHello challenge. Truncate or left-pad with // zeros as needed. size_t rand_len = CBS_len(&challenge); if (rand_len > SSL3_RANDOM_SIZE) { rand_len = SSL3_RANDOM_SIZE; } uint8_t random[SSL3_RANDOM_SIZE]; OPENSSL_memset(random, 0, SSL3_RANDOM_SIZE); OPENSSL_memcpy(random + (SSL3_RANDOM_SIZE - rand_len), CBS_data(&challenge), rand_len); // Write out an equivalent TLS ClientHello directly to the handshake buffer. size_t max_v3_client_hello = SSL3_HM_HEADER_LENGTH + 2 /* version */ + SSL3_RANDOM_SIZE + 1 /* session ID length */ + 2 /* cipher list length */ + CBS_len(&cipher_specs) / 3 * 2 + 1 /* compression length */ + 1 /* compression */; ScopedCBB client_hello; CBB hello_body, cipher_suites; if (!ssl->s3->hs_buf) { ssl->s3->hs_buf.reset(BUF_MEM_new()); } if (!ssl->s3->hs_buf || !BUF_MEM_reserve(ssl->s3->hs_buf.get(), max_v3_client_hello) || !CBB_init_fixed(client_hello.get(), (uint8_t *)ssl->s3->hs_buf->data, ssl->s3->hs_buf->max) || !CBB_add_u8(client_hello.get(), SSL3_MT_CLIENT_HELLO) || !CBB_add_u24_length_prefixed(client_hello.get(), &hello_body) || !CBB_add_u16(&hello_body, version) || !CBB_add_bytes(&hello_body, random, SSL3_RANDOM_SIZE) || // No session id. !CBB_add_u8(&hello_body, 0) || !CBB_add_u16_length_prefixed(&hello_body, &cipher_suites)) { OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE); return ssl_open_record_error; } // Copy the cipher suites. while (CBS_len(&cipher_specs) > 0) { uint32_t cipher_spec; if (!CBS_get_u24(&cipher_specs, &cipher_spec)) { OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR); return ssl_open_record_error; } // Skip SSLv2 ciphers. if ((cipher_spec & 0xff0000) != 0) { continue; } if (!CBB_add_u16(&cipher_suites, cipher_spec)) { OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR); return ssl_open_record_error; } } // Add the null compression scheme and finish. if (!CBB_add_u8(&hello_body, 1) || !CBB_add_u8(&hello_body, 0) || !CBB_finish(client_hello.get(), NULL, &ssl->s3->hs_buf->length)) { OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR); return ssl_open_record_error; } *out_consumed = 2 + msg_length; ssl->s3->is_v2_hello = true; return ssl_open_record_success; } static bool parse_message(const SSL *ssl, SSLMessage *out, size_t *out_bytes_needed) { if (!ssl->s3->hs_buf) { *out_bytes_needed = 4; return false; } CBS cbs; uint32_t len; CBS_init(&cbs, reinterpret_cast<const uint8_t *>(ssl->s3->hs_buf->data), ssl->s3->hs_buf->length); if (!CBS_get_u8(&cbs, &out->type) || !CBS_get_u24(&cbs, &len)) { *out_bytes_needed = 4; return false; } if (!CBS_get_bytes(&cbs, &out->body, len)) { *out_bytes_needed = 4 + len; return false; } CBS_init(&out->raw, reinterpret_cast<const uint8_t *>(ssl->s3->hs_buf->data), 4 + len); out->is_v2_hello = ssl->s3->is_v2_hello; return true; } bool tls_get_message(const SSL *ssl, SSLMessage *out) { size_t unused; if (!parse_message(ssl, out, &unused)) { return false; } if (!ssl->s3->has_message) { if (!out->is_v2_hello) { ssl_do_msg_callback(ssl, 0 /* read */, SSL3_RT_HANDSHAKE, out->raw); } ssl->s3->has_message = true; } return true; } bool tls_can_accept_handshake_data(const SSL *ssl, uint8_t *out_alert) { // If there is a complete message, the caller must have consumed it first. SSLMessage msg; size_t bytes_needed; if (parse_message(ssl, &msg, &bytes_needed)) { OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR); *out_alert = SSL_AD_INTERNAL_ERROR; return false; } // Enforce the limit so the peer cannot force us to buffer 16MB. if (bytes_needed > 4 + ssl_max_handshake_message_len(ssl)) { OPENSSL_PUT_ERROR(SSL, SSL_R_EXCESSIVE_MESSAGE_SIZE); *out_alert = SSL_AD_ILLEGAL_PARAMETER; return false; } return true; } bool tls_has_unprocessed_handshake_data(const SSL *ssl) { size_t msg_len = 0; if (ssl->s3->has_message) { SSLMessage msg; size_t unused; if (parse_message(ssl, &msg, &unused)) { msg_len = CBS_len(&msg.raw); } } return ssl->s3->hs_buf && ssl->s3->hs_buf->length > msg_len; } bool tls_append_handshake_data(SSL *ssl, Span<const uint8_t> data) { // Re-create the handshake buffer if needed. if (!ssl->s3->hs_buf) { ssl->s3->hs_buf.reset(BUF_MEM_new()); } return ssl->s3->hs_buf && BUF_MEM_append(ssl->s3->hs_buf.get(), data.data(), data.size()); } ssl_open_record_t tls_open_handshake(SSL *ssl, size_t *out_consumed, uint8_t *out_alert, Span<uint8_t> in) { *out_consumed = 0; // Bypass the record layer for the first message to handle V2ClientHello. if (ssl->server && !ssl->s3->v2_hello_done) { // Ask for the first 5 bytes, the size of the TLS record header. This is // sufficient to detect a V2ClientHello and ensures that we never read // beyond the first record. if (in.size() < SSL3_RT_HEADER_LENGTH) { *out_consumed = SSL3_RT_HEADER_LENGTH; return ssl_open_record_partial; } // Some dedicated error codes for protocol mixups should the application // wish to interpret them differently. (These do not overlap with // ClientHello or V2ClientHello.) const char *str = reinterpret_cast<const char*>(in.data()); if (strncmp("GET ", str, 4) == 0 || strncmp("POST ", str, 5) == 0 || strncmp("HEAD ", str, 5) == 0 || strncmp("PUT ", str, 4) == 0) { OPENSSL_PUT_ERROR(SSL, SSL_R_HTTP_REQUEST); *out_alert = 0; return ssl_open_record_error; } if (strncmp("CONNE", str, 5) == 0) { OPENSSL_PUT_ERROR(SSL, SSL_R_HTTPS_PROXY_REQUEST); *out_alert = 0; return ssl_open_record_error; } // Check for a V2ClientHello. if ((in[0] & 0x80) != 0 && in[2] == SSL2_MT_CLIENT_HELLO && in[3] == SSL3_VERSION_MAJOR) { auto ret = read_v2_client_hello(ssl, out_consumed, in); if (ret == ssl_open_record_error) { *out_alert = 0; } else if (ret == ssl_open_record_success) { ssl->s3->v2_hello_done = true; } return ret; } ssl->s3->v2_hello_done = true; } uint8_t type; Span<uint8_t> body; auto ret = tls_open_record(ssl, &type, &body, out_consumed, out_alert, in); if (ret != ssl_open_record_success) { return ret; } // WatchGuard's TLS 1.3 interference bug is very distinctive: they drop the // ServerHello and send the remaining encrypted application data records // as-is. This manifests as an application data record when we expect // handshake. Report a dedicated error code for this case. if (!ssl->server && type == SSL3_RT_APPLICATION_DATA && ssl->s3->aead_read_ctx->is_null_cipher()) { OPENSSL_PUT_ERROR(SSL, SSL_R_APPLICATION_DATA_INSTEAD_OF_HANDSHAKE); *out_alert = SSL_AD_UNEXPECTED_MESSAGE; return ssl_open_record_error; } if (type != SSL3_RT_HANDSHAKE) { OPENSSL_PUT_ERROR(SSL, SSL_R_UNEXPECTED_RECORD); *out_alert = SSL_AD_UNEXPECTED_MESSAGE; return ssl_open_record_error; } // Append the entire handshake record to the buffer. if (!tls_append_handshake_data(ssl, body)) { *out_alert = SSL_AD_INTERNAL_ERROR; return ssl_open_record_error; } return ssl_open_record_success; } void tls_next_message(SSL *ssl) { SSLMessage msg; if (!tls_get_message(ssl, &msg) || !ssl->s3->hs_buf || ssl->s3->hs_buf->length < CBS_len(&msg.raw)) { assert(0); return; } OPENSSL_memmove(ssl->s3->hs_buf->data, ssl->s3->hs_buf->data + CBS_len(&msg.raw), ssl->s3->hs_buf->length - CBS_len(&msg.raw)); ssl->s3->hs_buf->length -= CBS_len(&msg.raw); ssl->s3->is_v2_hello = false; ssl->s3->has_message = false; // Post-handshake messages are rare, so release the buffer after every // message. During the handshake, |on_handshake_complete| will release it. if (!SSL_in_init(ssl) && ssl->s3->hs_buf->length == 0) { ssl->s3->hs_buf.reset(); } } // CipherScorer produces a "score" for each possible cipher suite offered by // the client. class CipherScorer { public: CipherScorer(uint16_t group_id) : aes_is_fine_(EVP_has_aes_hardware()), security_128_is_fine_(group_id != SSL_CURVE_CECPQ2) {} typedef std::tuple<bool, bool, bool> Score; // MinScore returns a |Score| that will compare less than the score of all // cipher suites. Score MinScore() const { return Score(false, false, false); } Score Evaluate(const SSL_CIPHER *a) const { return Score( // Something is always preferable to nothing. true, // Either 128-bit is fine, or 256-bit is preferred. security_128_is_fine_ || a->algorithm_enc != SSL_AES128GCM, // Either AES is fine, or else ChaCha20 is preferred. aes_is_fine_ || a->algorithm_enc == SSL_CHACHA20POLY1305); } private: const bool aes_is_fine_; const bool security_128_is_fine_; }; const SSL_CIPHER *ssl_choose_tls13_cipher(CBS cipher_suites, uint16_t version, uint16_t group_id) { if (CBS_len(&cipher_suites) % 2 != 0) { return nullptr; } const SSL_CIPHER *best = nullptr; CipherScorer scorer(group_id); CipherScorer::Score best_score = scorer.MinScore(); while (CBS_len(&cipher_suites) > 0) { uint16_t cipher_suite; if (!CBS_get_u16(&cipher_suites, &cipher_suite)) { return nullptr; } // Limit to TLS 1.3 ciphers we know about. const SSL_CIPHER *candidate = SSL_get_cipher_by_value(cipher_suite); if (candidate == nullptr || SSL_CIPHER_get_min_version(candidate) > version || SSL_CIPHER_get_max_version(candidate) < version) { continue; } const CipherScorer::Score candidate_score = scorer.Evaluate(candidate); // |candidate_score| must be larger to displace the current choice. That way // the client's order controls between ciphers with an equal score. if (candidate_score > best_score) { best = candidate; best_score = candidate_score; } } return best; } BSSL_NAMESPACE_END