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boringssl/ssl/s3_both.cc

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/* 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/ssl.h>
#include <assert.h>
#include <limits.h>
#include <string.h>
#include <tuple>
#include <openssl/buf.h>
#include <openssl/bytestring.h>
#include <openssl/err.h>
#include <openssl/evp.h>
#include <openssl/mem.h>
#include <openssl/md5.h>
#include <openssl/nid.h>
#include <openssl/rand.h>
#include <openssl/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