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// Copyright (c) 2012 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.
#include "chrome/browser/component_updater/component_unpacker.h"
#include <string>
#include <vector>
#include "base/file_util.h"
#include "base/json/json_file_value_serializer.h"
#include "base/memory/scoped_handle.h"
#include "base/stringprintf.h"
#include "base/strings/string_number_conversions.h"
#include "chrome/browser/component_updater/component_updater_service.h"
#include "chrome/common/extensions/extension_constants.h"
#include "crypto/secure_hash.h"
#include "crypto/signature_verifier.h"
#include "extensions/common/crx_file.h"
#include "third_party/zlib/google/zip.h"
using crypto::SecureHash;
namespace {
// This class makes sure that the CRX digital signature is valid
// and well formed.
class CRXValidator {
public:
explicit CRXValidator(FILE* crx_file) : valid_(false) {
extensions::CrxFile::Header header;
size_t len = fread(&header, 1, sizeof(header), crx_file);
if (len < sizeof(header))
return;
extensions::CrxFile::Error error;
scoped_ptr<extensions::CrxFile> crx(
extensions::CrxFile::Parse(header, &error));
if (!crx.get())
return;
std::vector<uint8> key(header.key_size);
len = fread(&key[0], sizeof(uint8), header.key_size, crx_file);
if (len < header.key_size)
return;
std::vector<uint8> signature(header.signature_size);
len = fread(&signature[0], sizeof(uint8), header.signature_size, crx_file);
if (len < header.signature_size)
return;
crypto::SignatureVerifier verifier;
if (!verifier.VerifyInit(extension_misc::kSignatureAlgorithm,
sizeof(extension_misc::kSignatureAlgorithm),
&signature[0], signature.size(),
&key[0], key.size())) {
// Signature verification initialization failed. This is most likely
// caused by a public key in the wrong format (should encode algorithm).
return;
}
const size_t kBufSize = 8 * 1024;
scoped_ptr<uint8[]> buf(new uint8[kBufSize]);
while ((len = fread(buf.get(), 1, kBufSize, crx_file)) > 0)
verifier.VerifyUpdate(buf.get(), len);
if (!verifier.VerifyFinal())
return;
public_key_.swap(key);
valid_ = true;
}
bool valid() const { return valid_; }
const std::vector<uint8>& public_key() const { return public_key_; }
private:
bool valid_;
std::vector<uint8> public_key_;
};
// Deserialize the CRX manifest. The top level must be a dictionary.
// TODO(cpu): add a specific attribute check to a component json that the
// extension unpacker will reject, so that a component cannot be installed
// as an extension.
base::DictionaryValue* ReadManifest(const base::FilePath& unpack_path) {
base::FilePath manifest =
unpack_path.Append(FILE_PATH_LITERAL("manifest.json"));
if (!file_util::PathExists(manifest))
return NULL;
JSONFileValueSerializer serializer(manifest);
std::string error;
scoped_ptr<base::Value> root(serializer.Deserialize(NULL, &error));
if (!root.get())
return NULL;
if (!root->IsType(base::Value::TYPE_DICTIONARY))
return NULL;
return static_cast<base::DictionaryValue*>(root.release());
}
} // namespace.
ComponentUnpacker::ComponentUnpacker(const std::vector<uint8>& pk_hash,
const base::FilePath& path,
ComponentInstaller* installer)
: error_(kNone) {
if (pk_hash.empty() || path.empty()) {
error_ = kInvalidParams;
return;
}
// First, validate the CRX header and signature. As of today
// this is SHA1 with RSA 1024.
ScopedStdioHandle file(file_util::OpenFile(path, "rb"));
if (!file.get()) {
error_ = kInvalidFile;
return;
}
CRXValidator validator(file.get());
if (!validator.valid()) {
error_ = kInvalidFile;
return;
}
file.Close();
// File is valid and the digital signature matches. Now make sure
// the public key hash matches the expected hash. If they do we fully
// trust this CRX.
uint8 hash[32];
scoped_ptr<SecureHash> sha256(SecureHash::Create(SecureHash::SHA256));
sha256->Update(&(validator.public_key()[0]), validator.public_key().size());
sha256->Finish(hash, arraysize(hash));
if (!std::equal(pk_hash.begin(), pk_hash.end(), hash)) {
error_ = kInvalidId;
return;
}
// We want the temporary directory to be unique and yet predictable, so
// we can easily find the package in a end user machine.
std::string dir(
base::StringPrintf("CRX_%s", base::HexEncode(hash, 6).c_str()));
unpack_path_ = path.DirName().AppendASCII(dir.c_str());
if (file_util::DirectoryExists(unpack_path_)) {
if (!file_util::Delete(unpack_path_, true)) {
unpack_path_.clear();
error_ = kUzipPathError;
return;
}
}
if (!file_util::CreateDirectory(unpack_path_)) {
unpack_path_.clear();
error_ = kUzipPathError;
return;
}
if (!zip::Unzip(path, unpack_path_)) {
error_ = kUnzipFailed;
return;
}
scoped_ptr<base::DictionaryValue> manifest(ReadManifest(unpack_path_));
if (!manifest.get()) {
error_ = kBadManifest;
return;
}
if (!installer->Install(*manifest, unpack_path_)) {
error_ = kInstallerError;
return;
}
// Installation successful. The directory is not our concern now.
unpack_path_.clear();
}
ComponentUnpacker::~ComponentUnpacker() {
if (!unpack_path_.empty()) {
file_util::Delete(unpack_path_, true);
}
}
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