blob: a381e755e767deed696583ac5b1f1751ee6dfaa8 [file] [log] [blame]
/*
* Copyright 2014 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include "block_cipher_operation.h"
#include <stdio.h>
#include <keymaster/UniquePtr.h>
#include <openssl/aes.h>
#include <openssl/err.h>
#include <openssl/rand.h>
#include <keymaster/logger.h>
#include <keymaster/km_openssl/aes_key.h>
#include <keymaster/km_openssl/openssl_err.h>
#include <keymaster/km_openssl/openssl_utils.h>
namespace keymaster {
static const size_t GCM_NONCE_SIZE = 12;
inline bool allows_padding(keymaster_block_mode_t block_mode) {
switch (block_mode) {
case KM_MODE_CTR:
case KM_MODE_GCM:
return false;
case KM_MODE_ECB:
case KM_MODE_CBC:
return true;
}
assert(false /* Can't get here */);
return false;
}
static keymaster_error_t GetAndValidateGcmTagLength(const AuthorizationSet& begin_params,
const AuthProxy& key_params,
size_t* tag_length) {
uint32_t tag_length_bits;
if (!begin_params.GetTagValue(TAG_MAC_LENGTH, &tag_length_bits)) {
return KM_ERROR_MISSING_MAC_LENGTH;
}
uint32_t min_tag_length_bits;
if (!key_params.GetTagValue(TAG_MIN_MAC_LENGTH, &min_tag_length_bits)) {
LOG_E("AES GCM key must have KM_TAG_MIN_MAC_LENGTH", 0);
return KM_ERROR_INVALID_KEY_BLOB;
}
if (tag_length_bits % 8 != 0 || tag_length_bits > kMaxGcmTagLength ||
tag_length_bits < kMinGcmTagLength) {
return KM_ERROR_UNSUPPORTED_MAC_LENGTH;
}
if (tag_length_bits < min_tag_length_bits) {
return KM_ERROR_INVALID_MAC_LENGTH;
}
*tag_length = tag_length_bits / 8;
return KM_ERROR_OK;
}
OperationPtr BlockCipherOperationFactory::CreateOperation(Key&& key,
const AuthorizationSet& begin_params,
keymaster_error_t* error) {
*error = KM_ERROR_OK;
keymaster_block_mode_t block_mode;
if (!begin_params.GetTagValue(TAG_BLOCK_MODE, &block_mode)) {
LOG_E("%d block modes specified in begin params", begin_params.GetTagCount(TAG_BLOCK_MODE));
*error = KM_ERROR_UNSUPPORTED_BLOCK_MODE;
return nullptr;
} else if (!supported(block_mode)) {
LOG_E("Block mode %d not supported", block_mode);
*error = KM_ERROR_UNSUPPORTED_BLOCK_MODE;
return nullptr;
} else if (!key.authorizations().Contains(TAG_BLOCK_MODE, block_mode)) {
LOG_E("Block mode %d was specified, but not authorized by key", block_mode);
*error = KM_ERROR_INCOMPATIBLE_BLOCK_MODE;
return nullptr;
}
size_t tag_length = 0;
if (block_mode == KM_MODE_GCM) {
*error = GetAndValidateGcmTagLength(begin_params, key.authorizations(), &tag_length);
if (*error != KM_ERROR_OK) {
return nullptr;
}
}
keymaster_padding_t padding;
if (!GetAndValidatePadding(begin_params, key, &padding, error)) {
return nullptr;
}
if (!allows_padding(block_mode) && padding != KM_PAD_NONE) {
LOG_E("Mode does not support padding", 0);
*error = KM_ERROR_INCOMPATIBLE_PADDING_MODE;
return nullptr;
}
bool caller_nonce = key.authorizations().GetTagValue(TAG_CALLER_NONCE);
OperationPtr op;
switch (purpose_) {
case KM_PURPOSE_ENCRYPT:
op.reset(new (std::nothrow) BlockCipherEvpEncryptOperation( //
block_mode, padding, caller_nonce, tag_length, move(key), GetCipherDescription()));
break;
case KM_PURPOSE_DECRYPT:
op.reset(new (std::nothrow) BlockCipherEvpDecryptOperation(
block_mode, padding, tag_length, move(key), GetCipherDescription()));
break;
default:
*error = KM_ERROR_UNSUPPORTED_PURPOSE;
return nullptr;
}
if (!op) *error = KM_ERROR_MEMORY_ALLOCATION_FAILED;
return op;
}
static const keymaster_padding_t supported_padding_modes[] = {KM_PAD_NONE, KM_PAD_PKCS7};
const keymaster_padding_t*
BlockCipherOperationFactory::SupportedPaddingModes(size_t* padding_mode_count) const {
*padding_mode_count = array_length(supported_padding_modes);
return supported_padding_modes;
}
BlockCipherEvpOperation::BlockCipherEvpOperation(keymaster_purpose_t purpose,
keymaster_block_mode_t block_mode,
keymaster_padding_t padding, bool caller_iv,
size_t tag_length, Key&& key,
const EvpCipherDescription& cipher_description)
: Operation(purpose, key.hw_enforced_move(), key.sw_enforced_move()), block_mode_(block_mode),
caller_iv_(caller_iv), tag_length_(tag_length), data_started_(false), padding_(padding),
key_(key.key_material_move()), cipher_description_(cipher_description) {
EVP_CIPHER_CTX_init(&ctx_);
}
BlockCipherEvpOperation::~BlockCipherEvpOperation() {
EVP_CIPHER_CTX_cleanup(&ctx_);
}
keymaster_error_t BlockCipherEvpOperation::Begin(const AuthorizationSet& /* input_params */,
AuthorizationSet* /* output_params */) {
auto rc = GenerateRandom(reinterpret_cast<uint8_t*>(&operation_handle_),
(size_t)sizeof(operation_handle_));
if (rc != KM_ERROR_OK) return rc;
auto retval = InitializeCipher(key_);
key_ = {};
return retval;
}
keymaster_error_t BlockCipherEvpOperation::Update(const AuthorizationSet& additional_params,
const Buffer& input,
AuthorizationSet* /* output_params */,
Buffer* output, size_t* input_consumed) {
keymaster_error_t error;
if (block_mode_ == KM_MODE_GCM && !HandleAad(additional_params, input, &error)) return error;
if (!InternalUpdate(input.peek_read(), input.available_read(), output, &error)) return error;
*input_consumed = input.available_read();
return KM_ERROR_OK;
}
// NOLINTNEXTLINE(google-runtime-int)
inline bool is_bad_decrypt(unsigned long error) {
return (ERR_GET_LIB(error) == ERR_LIB_CIPHER && //
ERR_GET_REASON(error) == CIPHER_R_BAD_DECRYPT);
}
keymaster_error_t BlockCipherEvpOperation::Finish(const AuthorizationSet& additional_params,
const Buffer& input,
const Buffer& /* signature */,
AuthorizationSet* output_params, Buffer* output) {
keymaster_error_t error;
if (!UpdateForFinish(additional_params, input, output_params, output, &error)) return error;
if (!output->reserve(block_size_bytes())) return KM_ERROR_MEMORY_ALLOCATION_FAILED;
if (block_mode_ == KM_MODE_GCM && aad_block_buf_len_ > 0 && !ProcessBufferedAadBlock(&error)) {
return error;
}
int output_written = -1;
if (!EVP_CipherFinal_ex(&ctx_, output->peek_write(), &output_written)) {
if (tag_length_ > 0) return KM_ERROR_VERIFICATION_FAILED;
char buf[128];
ERR_error_string_n(ERR_peek_last_error(), buf, sizeof(buf));
LOG_E("Error encrypting final block: %s", buf);
return TranslateLastOpenSslError();
}
assert(output_written >= 0);
assert(static_cast<size_t>(output_written) <= block_size_bytes());
if (!output->advance_write(output_written)) return KM_ERROR_UNKNOWN_ERROR;
return KM_ERROR_OK;
}
bool BlockCipherEvpOperation::need_iv() const {
switch (block_mode_) {
case KM_MODE_CBC:
case KM_MODE_CTR:
case KM_MODE_GCM:
return true;
case KM_MODE_ECB:
return false;
default:
// Shouldn't get here.
assert(false);
return false;
}
}
keymaster_error_t BlockCipherEvpOperation::InitializeCipher(const KeymasterKeyBlob& key) {
keymaster_error_t error;
const EVP_CIPHER* cipher =
cipher_description_.GetCipherInstance(key.key_material_size, block_mode_, &error);
if (error) return error;
if (!EVP_CipherInit_ex(&ctx_, cipher, nullptr /* engine */, key.key_material, iv_.data,
evp_encrypt_mode())) {
return TranslateLastOpenSslError();
}
switch (padding_) {
case KM_PAD_NONE:
EVP_CIPHER_CTX_set_padding(&ctx_, 0 /* disable padding */);
break;
case KM_PAD_PKCS7:
// This is the default for OpenSSL EVP cipher operations.
break;
default:
return KM_ERROR_UNSUPPORTED_PADDING_MODE;
}
if (block_mode_ == KM_MODE_GCM) {
aad_block_buf_.reset(new (std::nothrow) uint8_t[block_size_bytes()]);
if (!aad_block_buf_) return KM_ERROR_MEMORY_ALLOCATION_FAILED;
aad_block_buf_len_ = 0;
}
return KM_ERROR_OK;
}
keymaster_error_t BlockCipherEvpOperation::GetIv(const AuthorizationSet& input_params) {
keymaster_blob_t iv_blob;
if (!input_params.GetTagValue(TAG_NONCE, &iv_blob)) {
LOG_E("No IV provided", 0);
return KM_ERROR_INVALID_ARGUMENT;
}
if (block_mode_ != KM_MODE_GCM && iv_blob.data_length != block_size_bytes()) {
LOG_E("Expected %d-byte IV for operation, but got %d bytes", block_size_bytes(),
iv_blob.data_length);
return KM_ERROR_INVALID_NONCE;
}
if (block_mode_ == KM_MODE_GCM && iv_blob.data_length != GCM_NONCE_SIZE) {
LOG_E("Expected %d-byte nonce for GCM operation, but got %d bytes", GCM_NONCE_SIZE,
iv_blob.data_length);
return KM_ERROR_INVALID_NONCE;
}
iv_ = KeymasterBlob(iv_blob.data, iv_blob.data_length);
if (!iv_.data) return KM_ERROR_MEMORY_ALLOCATION_FAILED;
return KM_ERROR_OK;
}
/*
* Process Incoming Associated Authentication Data.
*
* This method is more complex than might be expected, because the underlying library silently does
* the wrong thing when given partial AAD blocks, so we have to take care to process AAD in block
* size increments, buffering (in aad_block_buf_) when given smaller amounts of data.
*/
bool BlockCipherEvpOperation::HandleAad(const AuthorizationSet& input_params, const Buffer& input,
keymaster_error_t* error) {
assert(tag_length_ > 0);
assert(error);
keymaster_blob_t aad;
if (input_params.GetTagValue(TAG_ASSOCIATED_DATA, &aad)) {
if (data_started_) {
*error = KM_ERROR_INVALID_TAG;
return false;
}
if (aad_block_buf_len_ > 0) {
FillBufferedAadBlock(&aad);
if (aad_block_buf_len_ == block_size_bytes() && !ProcessBufferedAadBlock(error))
return false;
}
size_t block_size = block_size_bytes();
size_t blocks_to_process = aad.data_length / block_size;
if (blocks_to_process && !ProcessAadBlocks(aad.data, blocks_to_process, error))
return false;
aad.data += blocks_to_process * block_size;
aad.data_length -= blocks_to_process * block_size;
FillBufferedAadBlock(&aad);
assert(aad.data_length == 0);
}
if (input.available_read()) {
data_started_ = true;
// Data has begun, no more AAD is allowed. Process any buffered AAD.
if (aad_block_buf_len_ > 0 && !ProcessBufferedAadBlock(error)) return false;
}
return true;
}
bool BlockCipherEvpOperation::ProcessBufferedAadBlock(keymaster_error_t* error) {
int output_written;
if (EVP_CipherUpdate(&ctx_, nullptr /* out */, &output_written, aad_block_buf_.get(),
aad_block_buf_len_)) {
aad_block_buf_len_ = 0;
return true;
}
*error = TranslateLastOpenSslError();
return false;
}
bool BlockCipherEvpOperation::ProcessAadBlocks(const uint8_t* data, size_t blocks,
keymaster_error_t* error) {
int output_written;
if (EVP_CipherUpdate(&ctx_, nullptr /* out */, &output_written, data,
blocks * block_size_bytes())) {
return true;
}
*error = TranslateLastOpenSslError();
return false;
}
inline size_t min(size_t a, size_t b) {
return (a < b) ? a : b;
}
void BlockCipherEvpOperation::FillBufferedAadBlock(keymaster_blob_t* aad) {
size_t to_buffer = min(block_size_bytes() - aad_block_buf_len_, aad->data_length);
memcpy(aad_block_buf_.get() + aad_block_buf_len_, aad->data, to_buffer);
aad->data += to_buffer;
aad->data_length -= to_buffer;
aad_block_buf_len_ += to_buffer;
}
bool BlockCipherEvpOperation::InternalUpdate(const uint8_t* input, size_t input_length,
Buffer* output, keymaster_error_t* error) {
assert(output);
assert(error);
if (!input_length) return true;
if (!output->reserve(input_length + block_size_bytes())) {
*error = KM_ERROR_MEMORY_ALLOCATION_FAILED;
return false;
}
int output_written = -1;
if (!EVP_CipherUpdate(&ctx_, output->peek_write(), &output_written, input, input_length)) {
*error = TranslateLastOpenSslError();
return false;
}
return output->advance_write(output_written);
}
bool BlockCipherEvpOperation::UpdateForFinish(const AuthorizationSet& additional_params,
const Buffer& input, AuthorizationSet* output_params,
Buffer* output, keymaster_error_t* error) {
if (input.available_read() || !additional_params.empty()) {
size_t input_consumed;
*error = Update(additional_params, input, output_params, output, &input_consumed);
if (*error != KM_ERROR_OK) return false;
if (input_consumed != input.available_read()) {
*error = KM_ERROR_INVALID_INPUT_LENGTH;
return false;
}
}
return true;
}
keymaster_error_t BlockCipherEvpEncryptOperation::Begin(const AuthorizationSet& input_params,
AuthorizationSet* output_params) {
if (!output_params) return KM_ERROR_OUTPUT_PARAMETER_NULL;
if (need_iv()) {
keymaster_error_t error = KM_ERROR_OK;
if (input_params.find(TAG_NONCE) == -1) {
error = GenerateIv();
} else if (caller_iv_) {
error = GetIv(input_params);
} else {
error = KM_ERROR_CALLER_NONCE_PROHIBITED;
}
if (error != KM_ERROR_OK) return error;
output_params->push_back(TAG_NONCE, iv_.data, iv_.data_length);
}
return BlockCipherEvpOperation::Begin(input_params, output_params);
}
keymaster_error_t BlockCipherEvpEncryptOperation::Finish(const AuthorizationSet& additional_params,
const Buffer& input,
const Buffer& signature,
AuthorizationSet* output_params,
Buffer* output) {
if (!output->reserve(input.available_read() + block_size_bytes() + tag_length_)) {
return KM_ERROR_MEMORY_ALLOCATION_FAILED;
}
keymaster_error_t error =
BlockCipherEvpOperation::Finish(additional_params, input, signature, output_params, output);
if (error != KM_ERROR_OK) return error;
if (tag_length_ > 0) {
if (!output->reserve(tag_length_)) return KM_ERROR_MEMORY_ALLOCATION_FAILED;
if (!EVP_CIPHER_CTX_ctrl(&ctx_, EVP_CTRL_GCM_GET_TAG, tag_length_, output->peek_write()))
return TranslateLastOpenSslError();
if (!output->advance_write(tag_length_)) return KM_ERROR_UNKNOWN_ERROR;
}
return KM_ERROR_OK;
}
keymaster_error_t BlockCipherEvpEncryptOperation::GenerateIv() {
iv_.Reset((block_mode_ == KM_MODE_GCM) ? GCM_NONCE_SIZE : block_size_bytes());
if (!iv_.data) return KM_ERROR_MEMORY_ALLOCATION_FAILED;
if (RAND_bytes(iv_.writable_data(), iv_.data_length) != 1) return TranslateLastOpenSslError();
return KM_ERROR_OK;
}
keymaster_error_t BlockCipherEvpDecryptOperation::Begin(const AuthorizationSet& input_params,
AuthorizationSet* output_params) {
if (need_iv()) {
keymaster_error_t error = GetIv(input_params);
if (error != KM_ERROR_OK) return error;
}
if (tag_length_ > 0) {
tag_buf_.reset(new (std::nothrow) uint8_t[tag_length_]);
if (!tag_buf_) return KM_ERROR_MEMORY_ALLOCATION_FAILED;
tag_buf_len_ = 0;
}
return BlockCipherEvpOperation::Begin(input_params, output_params);
}
keymaster_error_t BlockCipherEvpDecryptOperation::Update(const AuthorizationSet& additional_params,
const Buffer& input,
AuthorizationSet* /* output_params */,
Buffer* output, size_t* input_consumed) {
if (!output || !input_consumed) return KM_ERROR_OUTPUT_PARAMETER_NULL;
// Barring error, we'll consume it all.
*input_consumed = input.available_read();
keymaster_error_t error;
if (block_mode_ == KM_MODE_GCM) {
if (!HandleAad(additional_params, input, &error)) return error;
return ProcessAllButTagLengthBytes(input, output);
}
if (!InternalUpdate(input.peek_read(), input.available_read(), output, &error)) return error;
return KM_ERROR_OK;
}
keymaster_error_t BlockCipherEvpDecryptOperation::ProcessAllButTagLengthBytes(const Buffer& input,
Buffer* output) {
if (input.available_read() <= tag_buf_unused()) {
BufferCandidateTagData(input.peek_read(), input.available_read());
return KM_ERROR_OK;
}
const size_t data_available = tag_buf_len_ + input.available_read();
const size_t to_process = data_available - tag_length_;
const size_t to_process_from_tag_buf = min(to_process, tag_buf_len_);
const size_t to_process_from_input = to_process - to_process_from_tag_buf;
if (!output->reserve(to_process + block_size_bytes())) return KM_ERROR_MEMORY_ALLOCATION_FAILED;
keymaster_error_t error;
if (!ProcessTagBufContentsAsData(to_process_from_tag_buf, output, &error)) return error;
if (!InternalUpdate(input.peek_read(), to_process_from_input, output, &error)) return error;
BufferCandidateTagData(input.peek_read() + to_process_from_input,
input.available_read() - to_process_from_input);
assert(tag_buf_unused() == 0);
return KM_ERROR_OK;
}
bool BlockCipherEvpDecryptOperation::ProcessTagBufContentsAsData(size_t to_process, Buffer* output,
keymaster_error_t* error) {
assert(to_process <= tag_buf_len_);
if (!InternalUpdate(tag_buf_.get(), to_process, output, error)) return false;
if (to_process < tag_buf_len_) {
memmove(tag_buf_.get(), tag_buf_.get() + to_process, tag_buf_len_ - to_process);
}
tag_buf_len_ -= to_process;
return true;
}
void BlockCipherEvpDecryptOperation::BufferCandidateTagData(const uint8_t* data,
size_t data_length) {
assert(data_length <= tag_length_ - tag_buf_len_);
memcpy(tag_buf_.get() + tag_buf_len_, data, data_length);
tag_buf_len_ += data_length;
}
keymaster_error_t BlockCipherEvpDecryptOperation::Finish(const AuthorizationSet& additional_params,
const Buffer& input,
const Buffer& signature,
AuthorizationSet* output_params,
Buffer* output) {
keymaster_error_t error;
if (!UpdateForFinish(additional_params, input, output_params, output, &error)) return error;
if (tag_buf_len_ < tag_length_) {
return KM_ERROR_INVALID_INPUT_LENGTH;
} else if (tag_length_ > 0 &&
!EVP_CIPHER_CTX_ctrl(&ctx_, EVP_CTRL_GCM_SET_TAG, tag_length_, tag_buf_.get())) {
return TranslateLastOpenSslError();
}
AuthorizationSet empty_params;
Buffer empty_input;
return BlockCipherEvpOperation::Finish(empty_params, empty_input, signature, output_params,
output);
}
keymaster_error_t BlockCipherEvpOperation::Abort() {
return KM_ERROR_OK;
}
} // namespace keymaster