android/libwvdrmengine/mediacrypto/src/WVCryptoPlugin.cpp

//
// Copyright 2021 Google LLC. All Rights Reserved. This file and proprietary
// source code may only be used and distributed under the Widevine License
// Agreement.
//

//#define LOG_NDEBUG 0
#define LOG_TAG "WVCdm"
#include "WVCryptoPlugin.h"

#include <aidlcommonsupport/NativeHandle.h>
#include <android/binder_ibinder_platform.h>
#include <sys/mman.h>
#include <utils/Log.h>

#include <algorithm>
#include <iterator>

#include "OEMCryptoCENC.h"
#include "Utils.h"
#include "WVErrors.h"
#include "log.h"
#include "mapErrors-inl.h"
#include "openssl/sha.h"
#include "wv_cdm_constants.h"

namespace wvdrm {
namespace hardware {
namespace drm {
namespace widevine {

using ::aidl::android::hardware::drm::DestinationBuffer;
using ::aidl::android::hardware::drm::Mode;
using ::aidl::android::hardware::drm::SharedBuffer;
using ::aidl::android::hardware::drm::Status;
using ::aidl::android::hardware::drm::SubSample;

using wvcdm::CdmDecryptionParametersV16;
using wvcdm::CdmDecryptionSample;
using wvcdm::CdmDecryptionSubsample;
using wvcdm::CdmQueryMap;
using wvcdm::CdmResponseType;
using wvcdm::CdmSessionId;
using wvcdm::KeyId;
using wvcdm::WvContentDecryptionModule;

WVCryptoPlugin::WVCryptoPlugin(
    const void* data, size_t size,
    const ::android::sp<WvContentDecryptionModule>& cdm)
    : mCDM(cdm), mUserId(wvutil::UNKNOWN_UID) {
  if (data != nullptr) {
    mSessionId.assign(static_cast<const char*>(data), size);
  }
  if (!mCDM->IsOpenSession(mSessionId)) {
    mSessionId.clear();
  } else {
    mCDM->GetSessionUserId(mSessionId, &mUserId);
  }
}

WVCryptoPlugin::~WVCryptoPlugin() {
  if (wvutil::UNKNOWN_UID != mUserId) {
    wvutil::SetLoggingUid(mUserId);
  }
}

SharedBufferBase::SharedBufferBase(
    const ::aidl::android::hardware::drm::SharedBuffer& mem) {
  set_base(nullptr);
  set_size(mem.size);
  if (mem.handle.fds.empty()) {
    return;
  }
  auto fd = mem.handle.fds[0].get();
  auto addr =
      mmap(nullptr, mem.size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
  if (addr == MAP_FAILED) {
    ALOGE("mmap err: fd %d; errno %s", fd, strerror(errno));
  } else {
    set_base(static_cast<uint8_t*>(addr));
  }
}

SharedBufferBase::~SharedBufferBase() {
  if (munmap(base(), size())) {
    ALOGE("munmap err: base %p; errno %s", base(), strerror(errno));
  }
}

::ndk::ScopedAStatus WVCryptoPlugin::requiresSecureDecoderComponent(
    const std::string& in_mime, bool* _aidl_return) {
  if (!strncasecmp(in_mime.c_str(), "video/", 6)) {
    // Type is video, so query CDM to see if we require a secure decoder.
    CdmQueryMap status;

    CdmResponseType res = mCDM->QuerySessionStatus(mSessionId, &status);

    if (!::wvdrm::isCdmResponseTypeSuccess(res)) {
      ALOGE("Error querying CDM status: %d", static_cast<int>(res));
      *_aidl_return = false;
      return ::ndk::ScopedAStatus::ok();
    }

    *_aidl_return = status[wvcdm::QUERY_KEY_SECURITY_LEVEL] ==
                    wvcdm::QUERY_VALUE_SECURITY_LEVEL_L1;
    return ::ndk::ScopedAStatus::ok();
  } else {
    // Type is not video, so never require a secure decoder.
    *_aidl_return = false;
    return ::ndk::ScopedAStatus::ok();
  }
}

::ndk::ScopedAStatus WVCryptoPlugin::notifyResolution(int32_t in_width,
                                                      int32_t in_height) {
  mCDM->NotifyResolution(mSessionId, in_width, in_height);
  return ::ndk::ScopedAStatus::ok();
}

::ndk::ScopedAStatus WVCryptoPlugin::setMediaDrmSession(
    const std::vector<uint8_t>& in_sessionId) {
  if (in_sessionId.size() == 0) {
    return toNdkScopedAStatus(Status::BAD_VALUE);
  }
  CdmSessionId cdmSessionId(in_sessionId.begin(), in_sessionId.end());
  if (!mCDM->IsOpenSession(cdmSessionId)) {
    return toNdkScopedAStatus(Status::ERROR_DRM_SESSION_NOT_OPENED);
  } else {
    mSessionId = cdmSessionId;
    return toNdkScopedAStatus(Status::OK);
  }
}

::ndk::ScopedAStatus WVCryptoPlugin::setSharedBufferBase(
    const ::aidl::android::hardware::drm::SharedBuffer& in_base) {
  std::lock_guard<std::mutex> shared_buffer_lock(mSharedBufferLock);

  mSharedBufferMap[in_base.bufferId] =
      std::make_shared<SharedBufferBase>(in_base);
  return ::ndk::ScopedAStatus::ok();
}

::ndk::ScopedAStatus WVCryptoPlugin::decrypt(
    const ::aidl::android::hardware::drm::DecryptArgs& in_args,
    int32_t* _aidl_return) {
  const char* detailedError = "";
  *_aidl_return = 0;  // bytes decrypted

  native_handle_t* handle = nullptr;
  uint8_t* srcPtr = nullptr;
  void* destPtr = nullptr;
  // Convert parameters to the form the CDM wishes to consume them in.
  const KeyId cryptoKey(in_args.keyId.begin(), in_args.keyId.end());

  // start scope for lock_guard
  {
    std::lock_guard<std::mutex> lock(mSharedBufferLock);
    if (mSharedBufferMap.find(in_args.source.bufferId) ==
        mSharedBufferMap.end()) {
      detailedError = "source decrypt buffer base not set";
      return toNdkScopedAStatus(Status::ERROR_DRM_CANNOT_HANDLE, detailedError);
    }

    const auto NON_SECURE = DestinationBuffer::Tag::nonsecureMemory;
    const auto SECURE = DestinationBuffer::Tag::secureMemory;
    if (in_args.destination.getTag() == NON_SECURE) {
      const SharedBuffer& dest = in_args.destination.get<NON_SECURE>();
      if (mSharedBufferMap.find(dest.bufferId) == mSharedBufferMap.end()) {
        detailedError = "destination decrypt buffer base not set";
        return toNdkScopedAStatus(Status::ERROR_DRM_CANNOT_HANDLE,
                                  detailedError);
      }
    }

    if (in_args.mode != Mode::UNENCRYPTED && in_args.mode != Mode::AES_CTR &&
        in_args.mode != Mode::AES_CBC) {
      detailedError =
          "The requested encryption mode is not supported by Widevine CDM.";
      return toNdkScopedAStatus(Status::BAD_VALUE, detailedError);
    } else if (in_args.mode == Mode::AES_CTR &&
               (in_args.pattern.encryptBlocks != 0 ||
                in_args.pattern.skipBlocks != 0)) {
      detailedError = "The 'cens' schema is not supported by Widevine CDM.";
      return toNdkScopedAStatus(Status::BAD_VALUE, detailedError);
    }

    auto src = mSharedBufferMap[in_args.source.bufferId];
    if (src->base() == nullptr) {
      detailedError = "source is a nullptr";
      return toNdkScopedAStatus(Status::ERROR_DRM_CANNOT_HANDLE, detailedError);
    }

    size_t totalSrcSize = 0;
    if (__builtin_add_overflow(in_args.source.offset, in_args.offset,
                               &totalSrcSize) ||
        __builtin_add_overflow(totalSrcSize, in_args.source.size,
                               &totalSrcSize) ||
        totalSrcSize > src->size()) {
      android_errorWriteLog(0x534e4554, "176496160");
      detailedError = "invalid source buffer size";
      return toNdkScopedAStatus(Status::ERROR_DRM_CANNOT_HANDLE, detailedError);
    }

    srcPtr = src->base() + in_args.source.offset + in_args.offset;

    if (in_args.destination.getTag() == NON_SECURE) {
      const SharedBuffer& destBuffer = in_args.destination.get<NON_SECURE>();
      auto dest = mSharedBufferMap[destBuffer.bufferId];
      if (dest->base() == nullptr) {
        detailedError = "destination is a nullptr";
        return toNdkScopedAStatus(Status::ERROR_DRM_CANNOT_HANDLE,
                                  detailedError);
      }
      size_t totalDstSize = 0;
      if (__builtin_add_overflow(destBuffer.offset, destBuffer.size,
                                 &totalDstSize) ||
          totalDstSize > dest->size()) {
        android_errorWriteLog(0x534e4554, "176444622");
        detailedError = "invalid buffer size";
        return toNdkScopedAStatus(Status::ERROR_DRM_FRAME_TOO_LARGE,
                                  detailedError);
      }
      destPtr = static_cast<void*>(
          dest->base() + in_args.destination.get<NON_SECURE>().offset);
    } else if (in_args.destination.getTag() == SECURE) {
      handle = android::makeFromAidl(in_args.destination.get<SECURE>());
      destPtr = static_cast<void*>(handle);
    }
  }  // lock_guard scope

  // Set up the decrypt params
  CdmDecryptionParametersV16 params;
  params.key_id = cryptoKey;
  params.is_secure = in_args.secure;
  if (in_args.mode == Mode::AES_CTR) {
    params.cipher_mode = wvcdm::kCipherModeCtr;
  } else if (in_args.mode == Mode::AES_CBC) {
    params.cipher_mode = wvcdm::kCipherModeCbc;
  }
  params.pattern.encrypt_blocks = in_args.pattern.encryptBlocks;
  params.pattern.skip_blocks = in_args.pattern.skipBlocks;

  // Set up the sample
  // Android's API only supports one at a time
  params.samples.emplace_back();
  CdmDecryptionSample& sample = params.samples.back();
  sample.encrypt_buffer = srcPtr;
  sample.decrypt_buffer = destPtr;
  sample.decrypt_buffer_offset = 0;
  sample.iv = in_args.iv;

  // Set up the subsamples
  // We abuse std::transform() here to also do some side-effects: Tallying the
  // total size of the sample and checking if any of the data is protected.
  size_t totalSize = 0;
  bool hasProtectedData = false;
  sample.subsamples.reserve(in_args.subSamples.size());
  std::transform(
      in_args.subSamples.data(),
      in_args.subSamples.data() + in_args.subSamples.size(),
      std::back_inserter(sample.subsamples),
      [&](const SubSample& subSample) -> CdmDecryptionSubsample {
        totalSize +=
            subSample.numBytesOfClearData + subSample.numBytesOfEncryptedData;
        hasProtectedData |= subSample.numBytesOfEncryptedData > 0;
        return CdmDecryptionSubsample(subSample.numBytesOfClearData,
                                      subSample.numBytesOfEncryptedData);
      });

  sample.encrypt_buffer_length = totalSize;
  sample.decrypt_buffer_size = totalSize;

  if (in_args.mode == Mode::UNENCRYPTED && hasProtectedData) {
    native_handle_delete(handle);
    detailedError = "Protected ranges found in allegedly clear data.";
    return toNdkScopedAStatus(Status::ERROR_DRM_CANNOT_HANDLE, detailedError);
  }

  // Decrypt
  std::string errorDetailMsg;
  auto res = attemptDecrypt(params, hasProtectedData, &errorDetailMsg);
  native_handle_delete(handle);
  if (res != Status::OK) {
    detailedError = errorDetailMsg.data();
    return toNdkScopedAStatus(res, detailedError);
  }

  *_aidl_return = totalSize;  // return bytes decrypted
  detailedError = errorDetailMsg.data();
  return toNdkScopedAStatus(Status::OK, detailedError);
}

::ndk::SpAIBinder WVCryptoPlugin::createBinder() {
  auto binder = BnCryptoPlugin::createBinder();
  AIBinder_setRequestingSid(binder.get(), true);
  return binder;
}

::wvdrm::WvStatus WVCryptoPlugin::attemptDecrypt(
    const CdmDecryptionParametersV16& params, bool hasProtectedData,
    std::string* errorDetailMsg) {
  CdmResponseType res = mCDM->DecryptV16(mSessionId, hasProtectedData, params);

  if (::wvdrm::isCdmResponseTypeSuccess(res)) {
    return ::wvdrm::WvStatus(Status::OK);
  } else {
    ALOGE("Decrypt error in session %s during a sample %s protected data: %d",
          mSessionId.c_str(), hasProtectedData ? "with" : "without", static_cast<int>(res));
    switch (res.code()) {
      case wvcdm::INSUFFICIENT_CRYPTO_RESOURCES:
        errorDetailMsg->assign(
            "Error decrypting data: insufficient crypto resources");
        break;
      case wvcdm::NEED_KEY:
      case wvcdm::KEY_NOT_FOUND_IN_SESSION:
        errorDetailMsg->assign(
            "Error decrypting data: requested key has not been loaded");
        break;
      case wvcdm::DECRYPT_NOT_READY:
        errorDetailMsg->assign(
            "Error decrypting data: license validity period is in the future");
        break;
      case wvcdm::SESSION_NOT_FOUND_FOR_DECRYPT:
        errorDetailMsg->assign(
            "Error decrypting data: session not found, possibly reclaimed");
        break;
      case wvcdm::DECRYPT_ERROR:
        errorDetailMsg->assign("Error decrypting data: unspecified error");
        break;
      case wvcdm::INSUFFICIENT_OUTPUT_PROTECTION:
      case wvcdm::ANALOG_OUTPUT_ERROR:
        errorDetailMsg->assign(
            "Error decrypting data: insufficient output protection");
        break;
      case wvcdm::KEY_PROHIBITED_FOR_SECURITY_LEVEL:
        errorDetailMsg->assign(
            "Error decrypting data: key prohibited for security level");
        break;
      default:
        break;
    }

    return ::wvdrm::mapCdmResponseType(res);
  }
}

::ndk::ScopedAStatus WVCryptoPlugin::getLogMessages(
    std::vector<::aidl::android::hardware::drm::LogMessage>* _aidl_return) {
  const std::vector<wvutil::LogMessage>& logs(wvutil::g_logbuf.getLogs());
  std::vector<::aidl::android::hardware::drm::LogMessage> msgs;
  for (auto log : logs) {
    msgs.push_back({log.time_ms_, ::wvdrm::toAidlLogPriority(log.priority_),
                    log.message_});
  }
  *_aidl_return = msgs;
  return ::wvdrm::toNdkScopedAStatus(Status::OK);
}

}  // namespace widevine
}  // namespace drm
}  // namespace hardware
}  // namespace wvdrm