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- /* Copyright (c) 2015, Google Inc.
- *
- * Permission to use, copy, modify, and/or distribute this software for any
- * purpose with or without fee is hereby granted, provided that the above
- * copyright notice and this permission notice appear in all copies.
- *
- * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
- * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
- * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
- * SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
- * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
- * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
- * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */
-
- #include <openssl/ssl.h>
-
- #include <assert.h>
- #include <string.h>
-
- #include <openssl/aead.h>
- #include <openssl/err.h>
- #include <openssl/rand.h>
-
- #include "../crypto/internal.h"
- #include "internal.h"
-
-
- #if defined(BORINGSSL_UNSAFE_FUZZER_MODE)
- #define FUZZER_MODE true
- #else
- #define FUZZER_MODE false
- #endif
-
- namespace bssl {
-
- SSLAEADContext::SSLAEADContext(uint16_t version_arg, bool is_dtls_arg,
- const SSL_CIPHER *cipher_arg)
- : cipher_(cipher_arg),
- version_(version_arg),
- is_dtls_(is_dtls_arg),
- variable_nonce_included_in_record_(false),
- random_variable_nonce_(false),
- omit_length_in_ad_(false),
- omit_version_in_ad_(false),
- omit_ad_(false),
- xor_fixed_nonce_(false) {
- OPENSSL_memset(fixed_nonce_, 0, sizeof(fixed_nonce_));
- }
-
- SSLAEADContext::~SSLAEADContext() {}
-
- UniquePtr<SSLAEADContext> SSLAEADContext::CreateNullCipher(bool is_dtls) {
- return MakeUnique<SSLAEADContext>(0 /* version */, is_dtls,
- nullptr /* cipher */);
- }
-
- UniquePtr<SSLAEADContext> SSLAEADContext::Create(
- enum evp_aead_direction_t direction, uint16_t version, int is_dtls,
- const SSL_CIPHER *cipher, Span<const uint8_t> enc_key,
- Span<const uint8_t> mac_key, Span<const uint8_t> fixed_iv) {
- const EVP_AEAD *aead;
- uint16_t protocol_version;
- size_t expected_mac_key_len, expected_fixed_iv_len;
- if (!ssl_protocol_version_from_wire(&protocol_version, version) ||
- !ssl_cipher_get_evp_aead(&aead, &expected_mac_key_len,
- &expected_fixed_iv_len, cipher, protocol_version,
- is_dtls) ||
- // Ensure the caller returned correct key sizes.
- expected_fixed_iv_len != fixed_iv.size() ||
- expected_mac_key_len != mac_key.size()) {
- OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
- return nullptr;
- }
-
- uint8_t merged_key[EVP_AEAD_MAX_KEY_LENGTH];
- if (!mac_key.empty()) {
- // This is a "stateful" AEAD (for compatibility with pre-AEAD cipher
- // suites).
- if (mac_key.size() + enc_key.size() + fixed_iv.size() >
- sizeof(merged_key)) {
- OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
- return nullptr;
- }
- OPENSSL_memcpy(merged_key, mac_key.data(), mac_key.size());
- OPENSSL_memcpy(merged_key + mac_key.size(), enc_key.data(), enc_key.size());
- OPENSSL_memcpy(merged_key + mac_key.size() + enc_key.size(),
- fixed_iv.data(), fixed_iv.size());
- enc_key = MakeConstSpan(merged_key,
- enc_key.size() + mac_key.size() + fixed_iv.size());
- }
-
- UniquePtr<SSLAEADContext> aead_ctx =
- MakeUnique<SSLAEADContext>(version, is_dtls, cipher);
- if (!aead_ctx) {
- OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE);
- return nullptr;
- }
-
- assert(aead_ctx->ProtocolVersion() == protocol_version);
-
- if (!EVP_AEAD_CTX_init_with_direction(
- aead_ctx->ctx_.get(), aead, enc_key.data(), enc_key.size(),
- EVP_AEAD_DEFAULT_TAG_LENGTH, direction)) {
- return nullptr;
- }
-
- assert(EVP_AEAD_nonce_length(aead) <= EVP_AEAD_MAX_NONCE_LENGTH);
- static_assert(EVP_AEAD_MAX_NONCE_LENGTH < 256,
- "variable_nonce_len doesn't fit in uint8_t");
- aead_ctx->variable_nonce_len_ = (uint8_t)EVP_AEAD_nonce_length(aead);
- if (mac_key.empty()) {
- assert(fixed_iv.size() <= sizeof(aead_ctx->fixed_nonce_));
- OPENSSL_memcpy(aead_ctx->fixed_nonce_, fixed_iv.data(), fixed_iv.size());
- aead_ctx->fixed_nonce_len_ = fixed_iv.size();
-
- if (cipher->algorithm_enc & SSL_CHACHA20POLY1305) {
- // The fixed nonce into the actual nonce (the sequence number).
- aead_ctx->xor_fixed_nonce_ = true;
- aead_ctx->variable_nonce_len_ = 8;
- } else {
- // The fixed IV is prepended to the nonce.
- assert(fixed_iv.size() <= aead_ctx->variable_nonce_len_);
- aead_ctx->variable_nonce_len_ -= fixed_iv.size();
- }
-
- // AES-GCM uses an explicit nonce.
- if (cipher->algorithm_enc & (SSL_AES128GCM | SSL_AES256GCM)) {
- aead_ctx->variable_nonce_included_in_record_ = true;
- }
-
- // The TLS 1.3 construction XORs the fixed nonce into the sequence number
- // and omits the additional data.
- if (protocol_version >= TLS1_3_VERSION) {
- aead_ctx->xor_fixed_nonce_ = true;
- aead_ctx->variable_nonce_len_ = 8;
- aead_ctx->variable_nonce_included_in_record_ = false;
- aead_ctx->omit_ad_ = true;
- assert(fixed_iv.size() >= aead_ctx->variable_nonce_len_);
- }
- } else {
- assert(protocol_version < TLS1_3_VERSION);
- aead_ctx->variable_nonce_included_in_record_ = true;
- aead_ctx->random_variable_nonce_ = true;
- aead_ctx->omit_length_in_ad_ = true;
- aead_ctx->omit_version_in_ad_ = (protocol_version == SSL3_VERSION);
- }
-
- return aead_ctx;
- }
-
- void SSLAEADContext::SetVersionIfNullCipher(uint16_t version) {
- if (is_null_cipher()) {
- version_ = version;
- }
- }
-
- uint16_t SSLAEADContext::ProtocolVersion() const {
- uint16_t protocol_version;
- if(!ssl_protocol_version_from_wire(&protocol_version, version_)) {
- assert(false);
- return 0;
- }
- return protocol_version;
- }
-
- uint16_t SSLAEADContext::RecordVersion() const {
- if (version_ == 0) {
- assert(is_null_cipher());
- return is_dtls_ ? DTLS1_VERSION : TLS1_VERSION;
- }
-
- if (ProtocolVersion() <= TLS1_2_VERSION) {
- return version_;
- }
-
- return TLS1_2_VERSION;
- }
-
- size_t SSLAEADContext::ExplicitNonceLen() const {
- if (!FUZZER_MODE && variable_nonce_included_in_record_) {
- return variable_nonce_len_;
- }
- return 0;
- }
-
- bool SSLAEADContext::SuffixLen(size_t *out_suffix_len, const size_t in_len,
- const size_t extra_in_len) const {
- if (is_null_cipher() || FUZZER_MODE) {
- *out_suffix_len = extra_in_len;
- return true;
- }
- return !!EVP_AEAD_CTX_tag_len(ctx_.get(), out_suffix_len, in_len,
- extra_in_len);
- }
-
- size_t SSLAEADContext::MaxOverhead() const {
- return ExplicitNonceLen() +
- (is_null_cipher() || FUZZER_MODE
- ? 0
- : EVP_AEAD_max_overhead(EVP_AEAD_CTX_aead(ctx_.get())));
- }
-
- size_t SSLAEADContext::GetAdditionalData(uint8_t out[13], uint8_t type,
- uint16_t record_version,
- const uint8_t seqnum[8],
- size_t plaintext_len) {
- if (omit_ad_) {
- return 0;
- }
-
- OPENSSL_memcpy(out, seqnum, 8);
- size_t len = 8;
- out[len++] = type;
- if (!omit_version_in_ad_) {
- out[len++] = static_cast<uint8_t>((record_version >> 8));
- out[len++] = static_cast<uint8_t>(record_version);
- }
- if (!omit_length_in_ad_) {
- out[len++] = static_cast<uint8_t>((plaintext_len >> 8));
- out[len++] = static_cast<uint8_t>(plaintext_len);
- }
- return len;
- }
-
- bool SSLAEADContext::Open(Span<uint8_t> *out, uint8_t type,
- uint16_t record_version, const uint8_t seqnum[8],
- Span<uint8_t> in) {
- if (is_null_cipher() || FUZZER_MODE) {
- // Handle the initial NULL cipher.
- *out = in;
- return true;
- }
-
- // TLS 1.2 AEADs include the length in the AD and are assumed to have fixed
- // overhead. Otherwise the parameter is unused.
- size_t plaintext_len = 0;
- if (!omit_length_in_ad_) {
- size_t overhead = MaxOverhead();
- if (in.size() < overhead) {
- // Publicly invalid.
- OPENSSL_PUT_ERROR(SSL, SSL_R_BAD_PACKET_LENGTH);
- return false;
- }
- plaintext_len = in.size() - overhead;
- }
- uint8_t ad[13];
- size_t ad_len =
- GetAdditionalData(ad, type, record_version, seqnum, plaintext_len);
-
- // Assemble the nonce.
- uint8_t nonce[EVP_AEAD_MAX_NONCE_LENGTH];
- size_t nonce_len = 0;
-
- // Prepend the fixed nonce, or left-pad with zeros if XORing.
- if (xor_fixed_nonce_) {
- nonce_len = fixed_nonce_len_ - variable_nonce_len_;
- OPENSSL_memset(nonce, 0, nonce_len);
- } else {
- OPENSSL_memcpy(nonce, fixed_nonce_, fixed_nonce_len_);
- nonce_len += fixed_nonce_len_;
- }
-
- // Add the variable nonce.
- if (variable_nonce_included_in_record_) {
- if (in.size() < variable_nonce_len_) {
- // Publicly invalid.
- OPENSSL_PUT_ERROR(SSL, SSL_R_BAD_PACKET_LENGTH);
- return false;
- }
- OPENSSL_memcpy(nonce + nonce_len, in.data(), variable_nonce_len_);
- in = in.subspan(variable_nonce_len_);
- } else {
- assert(variable_nonce_len_ == 8);
- OPENSSL_memcpy(nonce + nonce_len, seqnum, variable_nonce_len_);
- }
- nonce_len += variable_nonce_len_;
-
- // XOR the fixed nonce, if necessary.
- if (xor_fixed_nonce_) {
- assert(nonce_len == fixed_nonce_len_);
- for (size_t i = 0; i < fixed_nonce_len_; i++) {
- nonce[i] ^= fixed_nonce_[i];
- }
- }
-
- // Decrypt in-place.
- size_t len;
- if (!EVP_AEAD_CTX_open(ctx_.get(), in.data(), &len, in.size(), nonce,
- nonce_len, in.data(), in.size(), ad, ad_len)) {
- return false;
- }
- *out = in.subspan(0, len);
- return true;
- }
-
- bool SSLAEADContext::SealScatter(uint8_t *out_prefix, uint8_t *out,
- uint8_t *out_suffix, uint8_t type,
- uint16_t record_version,
- const uint8_t seqnum[8], const uint8_t *in,
- size_t in_len, const uint8_t *extra_in,
- size_t extra_in_len) {
- const size_t prefix_len = ExplicitNonceLen();
- size_t suffix_len;
- if (!SuffixLen(&suffix_len, in_len, extra_in_len)) {
- OPENSSL_PUT_ERROR(SSL, SSL_R_RECORD_TOO_LARGE);
- return false;
- }
- if ((in != out && buffers_alias(in, in_len, out, in_len)) ||
- buffers_alias(in, in_len, out_prefix, prefix_len) ||
- buffers_alias(in, in_len, out_suffix, suffix_len)) {
- OPENSSL_PUT_ERROR(SSL, SSL_R_OUTPUT_ALIASES_INPUT);
- return false;
- }
-
- if (is_null_cipher() || FUZZER_MODE) {
- // Handle the initial NULL cipher.
- OPENSSL_memmove(out, in, in_len);
- OPENSSL_memmove(out_suffix, extra_in, extra_in_len);
- return true;
- }
-
- uint8_t ad[13];
- size_t ad_len = GetAdditionalData(ad, type, record_version, seqnum, in_len);
-
- // Assemble the nonce.
- uint8_t nonce[EVP_AEAD_MAX_NONCE_LENGTH];
- size_t nonce_len = 0;
-
- // Prepend the fixed nonce, or left-pad with zeros if XORing.
- if (xor_fixed_nonce_) {
- nonce_len = fixed_nonce_len_ - variable_nonce_len_;
- OPENSSL_memset(nonce, 0, nonce_len);
- } else {
- OPENSSL_memcpy(nonce, fixed_nonce_, fixed_nonce_len_);
- nonce_len += fixed_nonce_len_;
- }
-
- // Select the variable nonce.
- if (random_variable_nonce_) {
- assert(variable_nonce_included_in_record_);
- if (!RAND_bytes(nonce + nonce_len, variable_nonce_len_)) {
- return false;
- }
- } else {
- // When sending we use the sequence number as the variable part of the
- // nonce.
- assert(variable_nonce_len_ == 8);
- OPENSSL_memcpy(nonce + nonce_len, seqnum, variable_nonce_len_);
- }
- nonce_len += variable_nonce_len_;
-
- // Emit the variable nonce if included in the record.
- if (variable_nonce_included_in_record_) {
- assert(!xor_fixed_nonce_);
- if (buffers_alias(in, in_len, out_prefix, variable_nonce_len_)) {
- OPENSSL_PUT_ERROR(SSL, SSL_R_OUTPUT_ALIASES_INPUT);
- return false;
- }
- OPENSSL_memcpy(out_prefix, nonce + fixed_nonce_len_,
- variable_nonce_len_);
- }
-
- // XOR the fixed nonce, if necessary.
- if (xor_fixed_nonce_) {
- assert(nonce_len == fixed_nonce_len_);
- for (size_t i = 0; i < fixed_nonce_len_; i++) {
- nonce[i] ^= fixed_nonce_[i];
- }
- }
-
- size_t written_suffix_len;
- bool result = !!EVP_AEAD_CTX_seal_scatter(
- ctx_.get(), out, out_suffix, &written_suffix_len, suffix_len, nonce,
- nonce_len, in, in_len, extra_in, extra_in_len, ad, ad_len);
- assert(!result || written_suffix_len == suffix_len);
- return result;
- }
-
- bool SSLAEADContext::Seal(uint8_t *out, size_t *out_len, size_t max_out_len,
- uint8_t type, uint16_t record_version,
- const uint8_t seqnum[8], const uint8_t *in,
- size_t in_len) {
- const size_t prefix_len = ExplicitNonceLen();
- size_t suffix_len;
- if (!SuffixLen(&suffix_len, in_len, 0)) {
- OPENSSL_PUT_ERROR(SSL, SSL_R_RECORD_TOO_LARGE);
- return false;
- }
- if (in_len + prefix_len < in_len ||
- in_len + prefix_len + suffix_len < in_len + prefix_len) {
- OPENSSL_PUT_ERROR(CIPHER, SSL_R_RECORD_TOO_LARGE);
- return false;
- }
- if (in_len + prefix_len + suffix_len > max_out_len) {
- OPENSSL_PUT_ERROR(SSL, SSL_R_BUFFER_TOO_SMALL);
- return false;
- }
-
- if (!SealScatter(out, out + prefix_len, out + prefix_len + in_len, type,
- record_version, seqnum, in, in_len, 0, 0)) {
- return false;
- }
- *out_len = prefix_len + in_len + suffix_len;
- return true;
- }
-
- bool SSLAEADContext::GetIV(const uint8_t **out_iv, size_t *out_iv_len) const {
- return !is_null_cipher() &&
- EVP_AEAD_CTX_get_iv(ctx_.get(), out_iv, out_iv_len);
- }
-
- } // namespace bssl
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