tenfourfox/media/gmp-clearkey/0.1/ClearKeyDecryptionManager.cpp
Cameron Kaiser c9b2922b70 hello FPR
2017-04-19 00:56:45 -07:00

237 lines
6.7 KiB
C++

/*
* Copyright 2015, Mozilla Foundation and contributors
*
* 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 <string.h>
#include <vector>
#include "ClearKeyDecryptionManager.h"
#include "gmp-api/gmp-decryption.h"
#include "mozilla/CheckedInt.h"
#include <assert.h>
class ClearKeyDecryptor : public RefCounted
{
public:
ClearKeyDecryptor();
void InitKey(const Key& aKey);
bool HasKey() const { return !!mKey.size(); }
GMPErr Decrypt(uint8_t* aBuffer, uint32_t aBufferSize,
const CryptoMetaData& aMetadata);
const Key& DecryptionKey() const { return mKey; }
private:
~ClearKeyDecryptor();
Key mKey;
};
/* static */ ClearKeyDecryptionManager* ClearKeyDecryptionManager::sInstance = nullptr;
/* static */ ClearKeyDecryptionManager*
ClearKeyDecryptionManager::Get()
{
if (!sInstance) {
sInstance = new ClearKeyDecryptionManager();
}
return sInstance;
}
ClearKeyDecryptionManager::ClearKeyDecryptionManager()
{
CK_LOGD("ClearKeyDecryptionManager::ClearKeyDecryptionManager");
}
ClearKeyDecryptionManager::~ClearKeyDecryptionManager()
{
CK_LOGD("ClearKeyDecryptionManager::~ClearKeyDecryptionManager");
sInstance = nullptr;
for (auto it = mDecryptors.begin(); it != mDecryptors.end(); it++) {
it->second->Release();
}
mDecryptors.clear();
}
bool
ClearKeyDecryptionManager::HasSeenKeyId(const KeyId& aKeyId) const
{
CK_LOGD("ClearKeyDecryptionManager::SeenKeyId %s", mDecryptors.find(aKeyId) != mDecryptors.end() ? "t" : "f");
return mDecryptors.find(aKeyId) != mDecryptors.end();
}
bool
ClearKeyDecryptionManager::IsExpectingKeyForKeyId(const KeyId& aKeyId) const
{
CK_LOGD("ClearKeyDecryptionManager::IsExpectingKeyForId %08x...", *(uint32_t*)&aKeyId[0]);
const auto& decryptor = mDecryptors.find(aKeyId);
return decryptor != mDecryptors.end() && !decryptor->second->HasKey();
}
bool
ClearKeyDecryptionManager::HasKeyForKeyId(const KeyId& aKeyId) const
{
CK_LOGD("ClearKeyDecryptionManager::HasKeyForKeyId");
const auto& decryptor = mDecryptors.find(aKeyId);
return decryptor != mDecryptors.end() && decryptor->second->HasKey();
}
const Key&
ClearKeyDecryptionManager::GetDecryptionKey(const KeyId& aKeyId)
{
assert(HasKeyForKeyId(aKeyId));
return mDecryptors[aKeyId]->DecryptionKey();
}
void
ClearKeyDecryptionManager::InitKey(KeyId aKeyId, Key aKey)
{
CK_LOGD("ClearKeyDecryptionManager::InitKey %08x...", *(uint32_t*)&aKeyId[0]);
if (IsExpectingKeyForKeyId(aKeyId)) {
mDecryptors[aKeyId]->InitKey(aKey);
}
}
void
ClearKeyDecryptionManager::ExpectKeyId(KeyId aKeyId)
{
CK_LOGD("ClearKeyDecryptionManager::ExpectKeyId %08x...", *(uint32_t*)&aKeyId[0]);
if (!HasSeenKeyId(aKeyId)) {
mDecryptors[aKeyId] = new ClearKeyDecryptor();
}
mDecryptors[aKeyId]->AddRef();
}
void
ClearKeyDecryptionManager::ReleaseKeyId(KeyId aKeyId)
{
CK_LOGD("ClearKeyDecryptionManager::ReleaseKeyId");
assert(HasSeenKeyId(aKeyId));
ClearKeyDecryptor* decryptor = mDecryptors[aKeyId];
if (!decryptor->Release()) {
mDecryptors.erase(aKeyId);
}
}
GMPErr
ClearKeyDecryptionManager::Decrypt(std::vector<uint8_t>& aBuffer,
const CryptoMetaData& aMetadata)
{
return Decrypt(&aBuffer[0], aBuffer.size(), aMetadata);
}
GMPErr
ClearKeyDecryptionManager::Decrypt(uint8_t* aBuffer, uint32_t aBufferSize,
const CryptoMetaData& aMetadata)
{
CK_LOGD("ClearKeyDecryptionManager::Decrypt");
if (!HasKeyForKeyId(aMetadata.mKeyId)) {
return GMPNoKeyErr;
}
return mDecryptors[aMetadata.mKeyId]->Decrypt(aBuffer, aBufferSize, aMetadata);
}
ClearKeyDecryptor::ClearKeyDecryptor()
{
CK_LOGD("ClearKeyDecryptor ctor");
}
ClearKeyDecryptor::~ClearKeyDecryptor()
{
CK_LOGD("ClearKeyDecryptor dtor; key = %08x...", *(uint32_t*)&mKey[0]);
}
void
ClearKeyDecryptor::InitKey(const Key& aKey)
{
mKey = aKey;
}
GMPErr
ClearKeyDecryptor::Decrypt(uint8_t* aBuffer, uint32_t aBufferSize,
const CryptoMetaData& aMetadata)
{
CK_LOGD("ClearKeyDecryptor::Decrypt");
// If the sample is split up into multiple encrypted subsamples, we need to
// stitch them into one continuous buffer for decryption.
std::vector<uint8_t> tmp(aBufferSize);
if (aMetadata.NumSubsamples()) {
// Take all encrypted parts of subsamples and stitch them into one
// continuous encrypted buffer.
static_assert(sizeof(uintptr_t) == sizeof(uint8_t*),
"We need uintptr_t to be exactly the same size as a pointer");
mozilla::CheckedInt<uintptr_t> data = reinterpret_cast<uintptr_t>(aBuffer);
const uintptr_t endBuffer =
reinterpret_cast<uintptr_t>(aBuffer + aBufferSize);
uint8_t* iter = &tmp[0];
for (size_t i = 0; i < aMetadata.NumSubsamples(); i++) {
data += aMetadata.mClearBytes[i];
if (!data.isValid() || data.value() > endBuffer) {
// Trying to read past the end of the buffer!
return GMPCryptoErr;
}
const uint32_t& cipherBytes = aMetadata.mCipherBytes[i];
mozilla::CheckedInt<uintptr_t> dataAfterCipher = data + cipherBytes;
if (!dataAfterCipher.isValid() || dataAfterCipher.value() > endBuffer) {
// Trying to read past the end of the buffer!
return GMPCryptoErr;
}
memcpy(iter, reinterpret_cast<uint8_t*>(data.value()), cipherBytes);
data = dataAfterCipher;
iter += cipherBytes;
}
tmp.resize((size_t)(iter - &tmp[0]));
} else {
memcpy(&tmp[0], aBuffer, aBufferSize);
}
assert(aMetadata.mIV.size() == 8 || aMetadata.mIV.size() == 16);
std::vector<uint8_t> iv(aMetadata.mIV);
iv.insert(iv.end(), CLEARKEY_KEY_LEN - aMetadata.mIV.size(), 0);
ClearKeyUtils::DecryptAES(mKey, tmp, iv);
if (aMetadata.NumSubsamples()) {
// Take the decrypted buffer, split up into subsamples, and insert those
// subsamples back into their original position in the original buffer.
uint8_t* data = aBuffer;
uint8_t* iter = &tmp[0];
for (size_t i = 0; i < aMetadata.NumSubsamples(); i++) {
data += aMetadata.mClearBytes[i];
uint32_t cipherBytes = aMetadata.mCipherBytes[i];
memcpy(data, iter, cipherBytes);
data += cipherBytes;
iter += cipherBytes;
}
} else {
memcpy(aBuffer, &tmp[0], aBufferSize);
}
return GMPNoErr;
}