electron/shell/common/asar/asar_util.cc

152 lines
4.4 KiB
C++

// Copyright (c) 2015 GitHub, Inc.
// Use of this source code is governed by the MIT license that can be
// found in the LICENSE file.
#include "shell/common/asar/asar_util.h"
#include <map>
#include <memory>
#include <string>
#include "base/files/file_path.h"
#include "base/files/file_util.h"
#include "base/logging.h"
#include "base/no_destructor.h"
#include "base/strings/string_number_conversions.h"
#include "base/strings/string_util.h"
#include "base/synchronization/lock.h"
#include "base/threading/thread_local.h"
#include "crypto/secure_hash.h"
#include "crypto/sha2.h"
#include "shell/common/asar/archive.h"
#include "shell/common/thread_restrictions.h"
namespace asar {
namespace {
typedef std::map<base::FilePath, std::shared_ptr<Archive>> ArchiveMap;
const base::FilePath::CharType kAsarExtension[] = FILE_PATH_LITERAL(".asar");
bool IsDirectoryCached(const base::FilePath& path) {
static base::NoDestructor<std::map<base::FilePath, bool>>
s_is_directory_cache;
static base::NoDestructor<base::Lock> lock;
base::AutoLock auto_lock(*lock);
auto& is_directory_cache = *s_is_directory_cache;
auto it = is_directory_cache.find(path);
if (it != is_directory_cache.end()) {
return it->second;
}
electron::ScopedAllowBlockingForElectron allow_blocking;
return is_directory_cache[path] = base::DirectoryExists(path);
}
ArchiveMap& GetArchiveCache() {
static base::NoDestructor<ArchiveMap> s_archive_map;
return *s_archive_map;
}
base::Lock& GetArchiveCacheLock() {
static base::NoDestructor<base::Lock> lock;
return *lock;
}
} // namespace
std::shared_ptr<Archive> GetOrCreateAsarArchive(const base::FilePath& path) {
base::AutoLock auto_lock(GetArchiveCacheLock());
ArchiveMap& map = GetArchiveCache();
// if we have it, return it
const auto lower = map.lower_bound(path);
if (lower != std::end(map) && !map.key_comp()(path, lower->first))
return lower->second;
// if we can create it, return it
auto archive = std::make_shared<Archive>(path);
if (archive->Init()) {
map.try_emplace(lower, path, archive);
return archive;
}
// didn't have it, couldn't create it
return nullptr;
}
bool GetAsarArchivePath(const base::FilePath& full_path,
base::FilePath* asar_path,
base::FilePath* relative_path,
bool allow_root) {
base::FilePath iter = full_path;
while (true) {
base::FilePath dirname = iter.DirName();
if (iter.MatchesExtension(kAsarExtension) && !IsDirectoryCached(iter))
break;
else if (iter == dirname)
return false;
iter = dirname;
}
base::FilePath tail;
if (!((allow_root && iter == full_path) ||
iter.AppendRelativePath(full_path, &tail)))
return false;
*asar_path = iter;
*relative_path = tail;
return true;
}
bool ReadFileToString(const base::FilePath& path, std::string* contents) {
base::FilePath asar_path, relative_path;
if (!GetAsarArchivePath(path, &asar_path, &relative_path))
return base::ReadFileToString(path, contents);
std::shared_ptr<Archive> archive = GetOrCreateAsarArchive(asar_path);
if (!archive)
return false;
Archive::FileInfo info;
if (!archive->GetFileInfo(relative_path, &info))
return false;
if (info.unpacked) {
base::FilePath real_path;
// For unpacked file it will return the real path instead of doing the copy.
archive->CopyFileOut(relative_path, &real_path);
return base::ReadFileToString(real_path, contents);
}
base::File src(asar_path, base::File::FLAG_OPEN | base::File::FLAG_READ);
if (!src.IsValid())
return false;
contents->resize(info.size);
if (!src.ReadAndCheck(info.offset, base::as_writable_byte_span(*contents)))
return false;
if (info.integrity)
ValidateIntegrityOrDie(base::as_byte_span(*contents), *info.integrity);
return true;
}
void ValidateIntegrityOrDie(base::span<const uint8_t> input,
const IntegrityPayload& integrity) {
if (integrity.algorithm == HashAlgorithm::kSHA256) {
const std::string hex_hash =
base::ToLowerASCII(base::HexEncode(crypto::SHA256Hash(input)));
if (integrity.hash != hex_hash) {
LOG(FATAL) << "Integrity check failed for asar archive ("
<< integrity.hash << " vs " << hex_hash << ")";
}
} else {
LOG(FATAL) << "Unsupported hashing algorithm in ValidateIntegrityOrDie";
}
}
} // namespace asar