android/libwvdrmengine/tools/factory_upload_tool/src/WidevineOemcryptoInterface.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.

#include "WidevineOemcryptoInterface.h"

#include <dlfcn.h>

#include "OEMCryptoCENC.h"
#include "clock.h"
#include "file_store.h"
#include "log.h"

// These macros lookup the obfuscated name used for OEMCrypto.
#define QUOTE_DEFINE(A) #A
#define QUOTE(A) QUOTE_DEFINE(A)
#define LOOKUP(handle, name) dlsym(handle, QUOTE(name))
#define LOAD_SYM(name)                                                  \
  name = reinterpret_cast<name##_t>(LOOKUP(handle_, OEMCrypto_##name)); \
  if (name == nullptr) {                                                \
    LOGE("%s", dlerror());                                              \
    return false;                                                       \
  }
#define LOAD_SYM_IF_EXIST(name) \
  name = reinterpret_cast<name##_t>(LOOKUP(handle_, OEMCrypto_##name));

// These are implementations required by OEMCrypto Reference Implementation
// and/or the Testbed, but not needed in this package.
namespace wvutil {
int64_t Clock::GetCurrentTime() { return 0; }

class FileImpl final : public File {
 public:
  FileImpl() {}
  ssize_t Read(char*, size_t) override { return 0; }
  ssize_t Write(const char*, size_t) override { return 0; }
};

class FileSystem::Impl {
 public:
  Impl() {}
};

FileSystem::FileSystem() {}
FileSystem::FileSystem(const std::string&, void*) {}
FileSystem::~FileSystem() {}
std::unique_ptr<File> FileSystem::Open(const std::string&, int) {
  return std::unique_ptr<File>(new FileImpl());
}
bool FileSystem::Exists(const std::string&) { return false; }
bool FileSystem::Remove(const std::string&) { return false; }
ssize_t FileSystem::FileSize(const std::string&) { return false; }
bool FileSystem::List(const std::string&, std::vector<std::string>*) {
  return false;
}

}  // namespace wvutil

namespace widevine {

OEMCryptoInterface::~OEMCryptoInterface() {
  if (Terminate != nullptr) {
    Terminate();
  }
  if (handle_ != nullptr) {
    dlclose(handle_);
  }
}

bool OEMCryptoInterface::Init(const std::string& oemcrypto_path) {
  dlerror();
  handle_ = dlopen(oemcrypto_path.c_str(), RTLD_LAZY | RTLD_GLOBAL);
  if (handle_ == nullptr) {
    LOGE("Can't open OEMCrypto library: %s", dlerror());
    return false;
  }
  LOGI("OEMCrypto library opened.");

  LOAD_SYM(Initialize);
  LOAD_SYM(Terminate);
  LOAD_SYM(GetBootCertificateChain);
  LOAD_SYM(BuildInformation);
  LOAD_SYM_IF_EXIST(GetDeviceInformation);
  LOAD_SYM_IF_EXIST(GetDeviceSignedCsrPayload);

  OEMCryptoResult status = Initialize();
  if (status != OEMCrypto_SUCCESS) {
    LOGE("OEMCrypto Initialize failed: %d", status);
    return false;
  }
  return true;
}

OEMCryptoResult OEMCryptoInterface::GetBcc(std::vector<uint8_t>& bcc) {
  if (handle_ == nullptr) {
    return OEMCrypto_ERROR_INIT_FAILED;
  }

  bcc.resize(0);
  size_t bcc_size = 0;

  std::vector<uint8_t> additional_signature;  // It should be empty.
  size_t additional_signature_size = 0;
  OEMCryptoResult result = GetBootCertificateChain(bcc.data(), &bcc_size,
                                                   additional_signature.data(),
                                                   &additional_signature_size);
  LOGI("GetBootCertificateChain first attempt result %d", result);
  if (additional_signature_size != 0) {
    LOGW(
        "The additional_signature_size required by OEMCrypto is %zu, while it "
        "is expected to be zero.",
        additional_signature_size);
  }

  if (result == OEMCrypto_ERROR_SHORT_BUFFER) {
    bcc.resize(bcc_size);
    additional_signature.resize(additional_signature_size);
    result = GetBootCertificateChain(bcc.data(), &bcc_size,
                                     additional_signature.data(),
                                     &additional_signature_size);
    if (result == OEMCrypto_SUCCESS) bcc.resize(bcc_size);
    LOGI("GetBootCertificateChain second attempt result %d", result);
  }

  return result;
}

OEMCryptoResult OEMCryptoInterface::GetOEMCryptoBuildInfo(
    std::string& build_info) {
  if (handle_ == nullptr) {
    return OEMCrypto_ERROR_INIT_FAILED;
  }

  build_info.resize(0);
  size_t build_info_size = 0;

  OEMCryptoResult result = BuildInformation(&build_info[0], &build_info_size);
  LOGI("BuildInformation first attempt result %d", result);
  if (result == OEMCrypto_ERROR_SHORT_BUFFER) {
    build_info.resize(build_info_size);
    result = BuildInformation(&build_info[0], &build_info_size);
    LOGI("BuildInformation second attempt result %d", result);
  }

  return result;
}

OEMCryptoResult OEMCryptoInterface::GetVerifiedDeviceInformation(
    std::vector<uint8_t>& verified_device_info) {
  if (handle_ == nullptr) {
    return OEMCrypto_ERROR_INIT_FAILED;
  }
  if (GetDeviceInformation == nullptr) {
    return OEMCrypto_ERROR_NOT_IMPLEMENTED;
  }

  verified_device_info.resize(0);
  size_t verified_device_info_size = 0;
  OEMCryptoResult result = GetDeviceInformation(verified_device_info.data(),
                                                &verified_device_info_size);
  LOGI("GetVerifiedDeviceInformation first attempt result %d", result);
  if (result == OEMCrypto_ERROR_SHORT_BUFFER) {
    verified_device_info.resize(verified_device_info_size);
    result = GetDeviceInformation(verified_device_info.data(),
                                  &verified_device_info_size);
    verified_device_info.resize(verified_device_info_size);
    LOGI("GetVerifiedDeviceInformation second attempt result %d", result);
  }
  return result;
}

OEMCryptoResult OEMCryptoInterface::GetSignedCsrPayload(
    const std::vector<uint8_t>& challenge,
    const std::vector<uint8_t>& device_info,
    std::vector<uint8_t>& signed_csr_payload) {
  if (handle_ == nullptr) {
    return OEMCrypto_ERROR_INIT_FAILED;
  }
  if (GetDeviceSignedCsrPayload == nullptr) {
    return OEMCrypto_ERROR_NOT_IMPLEMENTED;
  }

  size_t signed_csr_payload_size = signed_csr_payload.size();
  OEMCryptoResult result = GetDeviceSignedCsrPayload(
      challenge.data(), challenge.size(), device_info.data(),
      device_info.size(), signed_csr_payload.data(), &signed_csr_payload_size);
  LOGI("GetDeviceSignedCsrPayload first attempt result %d", result);
  if (result == OEMCrypto_ERROR_SHORT_BUFFER) {
    signed_csr_payload.resize(signed_csr_payload_size);
    result = GetDeviceSignedCsrPayload(challenge.data(), challenge.size(),
                                       device_info.data(), device_info.size(),
                                       signed_csr_payload.data(),
                                       &signed_csr_payload_size);
    signed_csr_payload.resize(signed_csr_payload_size);
    LOGI("GetDeviceSignedCsrPayload second attempt result %d", result);
  }
  return result;
}

}  // namespace widevine