ref: ca70040abf8d8ab2cb03575f65131ad8ef8f12a1
dir: /third_party/boringssl/src/ssl/ssl_aead_ctx.cc/
/* 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
BSSL_NAMESPACE_BEGIN
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),
xor_fixed_nonce_(false),
omit_length_in_ad_(false),
ad_is_header_(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, bool 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->ad_is_header_ = 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;
}
return aead_ctx;
}
UniquePtr<SSLAEADContext> SSLAEADContext::CreatePlaceholderForQUIC(
uint16_t version, const SSL_CIPHER *cipher) {
return MakeUnique<SSLAEADContext>(version, false, cipher);
}
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);
}
bool SSLAEADContext::CiphertextLen(size_t *out_len, const size_t in_len,
const size_t extra_in_len) const {
size_t len;
if (!SuffixLen(&len, in_len, extra_in_len)) {
return false;
}
len += ExplicitNonceLen();
len += in_len;
if (len < in_len || len >= 0xffff) {
OPENSSL_PUT_ERROR(SSL, ERR_R_OVERFLOW);
return false;
}
*out_len = len;
return true;
}
size_t SSLAEADContext::MaxOverhead() const {
return ExplicitNonceLen() +
(is_null_cipher() || FUZZER_MODE
? 0
: EVP_AEAD_max_overhead(EVP_AEAD_CTX_aead(ctx_.get())));
}
Span<const uint8_t> SSLAEADContext::GetAdditionalData(
uint8_t storage[13], uint8_t type, uint16_t record_version,
const uint8_t seqnum[8], size_t plaintext_len, Span<const uint8_t> header) {
if (ad_is_header_) {
return header;
}
OPENSSL_memcpy(storage, seqnum, 8);
size_t len = 8;
storage[len++] = type;
storage[len++] = static_cast<uint8_t>((record_version >> 8));
storage[len++] = static_cast<uint8_t>(record_version);
if (!omit_length_in_ad_) {
storage[len++] = static_cast<uint8_t>((plaintext_len >> 8));
storage[len++] = static_cast<uint8_t>(plaintext_len);
}
return MakeConstSpan(storage, len);
}
bool SSLAEADContext::Open(Span<uint8_t> *out, uint8_t type,
uint16_t record_version, const uint8_t seqnum[8],
Span<const uint8_t> header, 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_storage[13];
Span<const uint8_t> ad = GetAdditionalData(ad_storage, type, record_version,
seqnum, plaintext_len, header);
// 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.data(),
ad.size())) {
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],
Span<const uint8_t> header, 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_storage[13];
Span<const uint8_t> ad = GetAdditionalData(ad_storage, type, record_version,
seqnum, in_len, header);
// 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.data(), ad.size());
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], Span<const uint8_t> header,
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, header, 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);
}
BSSL_NAMESPACE_END