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// Copyright 2017 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
//
// This file contains the archive file analysis implementation for download
// protection, which runs in a sandboxed utility process.
#include "chrome/common/safe_browsing/archive_analyzer_results.h"
#include "base/files/file.h"
#include "base/i18n/streaming_utf8_validator.h"
#include "base/memory/scoped_refptr.h"
#include "base/stl_util.h"
#include "build/build_config.h"
#include "chrome/common/safe_browsing/archive_analyzer_results.h"
#include "chrome/common/safe_browsing/binary_feature_extractor.h"
#include "chrome/common/safe_browsing/download_type_util.h"
#include "chrome/common/safe_browsing/file_type_policies.h"
#include "crypto/secure_hash.h"
#include "crypto/sha2.h"
#if defined(OS_MACOSX)
#include <mach-o/fat.h>
#include <mach-o/loader.h>
#include "base/containers/span.h"
#include "chrome/common/safe_browsing/disk_image_type_sniffer_mac.h"
#include "chrome/common/safe_browsing/mach_o_image_reader_mac.h"
#endif // OS_MACOSX
namespace safe_browsing {
namespace {
void SetLengthAndDigestForContainedFile(
const base::FilePath& path,
base::File* temp_file,
int file_length,
ClientDownloadRequest::ArchivedBinary* archived_binary) {
std::string file_basename(path.BaseName().AsUTF8Unsafe());
if (base::StreamingUtf8Validator::Validate(file_basename))
archived_binary->set_file_basename(file_basename);
archived_binary->set_length(file_length);
std::unique_ptr<crypto::SecureHash> hasher =
crypto::SecureHash::Create(crypto::SecureHash::SHA256);
const size_t kReadBufferSize = 4096;
char block[kReadBufferSize];
int bytes_read_previously = 0;
temp_file->Seek(base::File::Whence::FROM_BEGIN, 0);
while (true) {
int bytes_read_now = temp_file->ReadAtCurrentPos(block, kReadBufferSize);
if (bytes_read_previously + bytes_read_now > file_length)
bytes_read_now = file_length - bytes_read_previously;
if (bytes_read_now <= 0)
break;
hasher->Update(block, bytes_read_now);
bytes_read_previously += bytes_read_now;
}
uint8_t digest[crypto::kSHA256Length];
hasher->Finish(digest, base::size(digest));
archived_binary->mutable_digests()->set_sha256(digest, base::size(digest));
}
void AnalyzeContainedBinary(
const scoped_refptr<BinaryFeatureExtractor>& binary_feature_extractor,
base::File* temp_file,
ClientDownloadRequest::ArchivedBinary* archived_binary) {
if (!binary_feature_extractor->ExtractImageFeaturesFromFile(
temp_file->Duplicate(), BinaryFeatureExtractor::kDefaultOptions,
archived_binary->mutable_image_headers(),
archived_binary->mutable_signature()->mutable_signed_data())) {
archived_binary->clear_image_headers();
archived_binary->clear_signature();
} else if (!archived_binary->signature().signed_data_size()) {
// No SignedData blobs were extracted, so clear the
// signature field.
archived_binary->clear_signature();
}
}
} // namespace
ArchiveAnalyzerResults::ArchiveAnalyzerResults()
: success(false),
has_executable(false),
has_archive(false),
file_count(0),
directory_count(0) {}
ArchiveAnalyzerResults::ArchiveAnalyzerResults(
const ArchiveAnalyzerResults& other) = default;
ArchiveAnalyzerResults::~ArchiveAnalyzerResults() {}
void UpdateArchiveAnalyzerResultsWithFile(base::FilePath path,
base::File* file,
int file_length,
bool is_encrypted,
ArchiveAnalyzerResults* results) {
scoped_refptr<BinaryFeatureExtractor> binary_feature_extractor(
new BinaryFeatureExtractor());
bool current_entry_is_executable;
#if defined(OS_MACOSX)
uint32_t magic;
file->Read(0, reinterpret_cast<char*>(&magic), sizeof(uint32_t));
char dmg_header[DiskImageTypeSnifferMac::AppleDiskImageTrailerSize()];
file->Read(0, dmg_header,
DiskImageTypeSnifferMac::AppleDiskImageTrailerSize());
current_entry_is_executable =
FileTypePolicies::GetInstance()->IsCheckedBinaryFile(path) ||
MachOImageReader::IsMachOMagicValue(magic) ||
DiskImageTypeSnifferMac::IsAppleDiskImageTrailer(
base::span<const uint8_t>(
reinterpret_cast<const uint8_t*>(dmg_header),
DiskImageTypeSnifferMac::AppleDiskImageTrailerSize()));
// We can skip checking the trailer if we already know the file is executable.
if (!current_entry_is_executable) {
char trailer[DiskImageTypeSnifferMac::AppleDiskImageTrailerSize()];
file->Seek(base::File::Whence::FROM_END,
DiskImageTypeSnifferMac::AppleDiskImageTrailerSize());
file->ReadAtCurrentPos(
trailer, DiskImageTypeSnifferMac::AppleDiskImageTrailerSize());
current_entry_is_executable =
DiskImageTypeSnifferMac::IsAppleDiskImageTrailer(
base::span<const uint8_t>(
reinterpret_cast<const uint8_t*>(trailer),
DiskImageTypeSnifferMac::AppleDiskImageTrailerSize()));
}
#else
current_entry_is_executable =
FileTypePolicies::GetInstance()->IsCheckedBinaryFile(path);
#endif // OS_MACOSX
if (FileTypePolicies::GetInstance()->IsArchiveFile(path)) {
DVLOG(2) << "Downloaded a zipped archive: " << path.value();
results->has_archive = true;
results->archived_archive_filenames.push_back(path.BaseName());
ClientDownloadRequest::ArchivedBinary* archived_archive =
results->archived_binary.Add();
archived_archive->set_download_type(ClientDownloadRequest::ARCHIVE);
archived_archive->set_is_encrypted(is_encrypted);
SetLengthAndDigestForContainedFile(path, file, file_length,
archived_archive);
} else if (current_entry_is_executable) {
#if defined(OS_MACOSX)
// This check prevents running analysis on .app files since they are
// really just directories and will cause binary feature extraction
// to fail.
if (path.Extension().compare(".app") == 0) {
DVLOG(2) << "Downloaded a zipped .app directory: " << path.value();
} else {
#endif // OS_MACOSX
DVLOG(2) << "Downloaded a zipped executable: " << path.value();
results->has_executable = true;
ClientDownloadRequest::ArchivedBinary* archived_binary =
results->archived_binary.Add();
archived_binary->set_is_encrypted(is_encrypted);
archived_binary->set_download_type(
download_type_util::GetDownloadType(path));
SetLengthAndDigestForContainedFile(path, file, file_length,
archived_binary);
AnalyzeContainedBinary(binary_feature_extractor, file, archived_binary);
#if defined(OS_MACOSX)
}
#endif // OS_MACOSX
} else {
DVLOG(3) << "Ignoring non-binary file: " << path.value();
}
}
} // namespace safe_browsing
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