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// Copyright 2014 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef EXTENSIONS_BROWSER_VERIFIED_CONTENTS_H_
#define EXTENSIONS_BROWSER_VERIFIED_CONTENTS_H_
#include <stdint.h>
#include <map>
#include <memory>
#include <string>
#include <string_view>
#include <vector>
#include "base/containers/span.h"
#include "base/files/file_path.h"
#include "base/memory/raw_span.h"
#include "base/version.h"
#include "extensions/browser/content_verifier/content_verifier_utils.h"
#include "extensions/common/extension_id.h"
namespace extensions {
using CanonicalRelativePath = content_verifier_utils::CanonicalRelativePath;
// This class encapsulates the data in a "verified_contents.json" file
// generated by the webstore for a .crx file. That data includes a set of
// signed expected hashes of file content which can be used to check for
// corruption of extension files on local disk.
class VerifiedContents {
public:
VerifiedContents(const VerifiedContents&) = delete;
VerifiedContents& operator=(const VerifiedContents&) = delete;
~VerifiedContents();
// Returns verified contents after successfully parsing verified_contents.json
// file at `path` and validating the enclosed signature. Returns nullptr on
// failure.
// Note: `public_key` must remain valid for the lifetime of the returned
// object.
static std::unique_ptr<VerifiedContents> CreateFromFile(
base::span<const uint8_t> public_key,
const base::FilePath& path);
// Returns verified contents after successfully parsing `contents` and
// validating the enclosed signature. Returns nullptr on failure. Note:
// `public_key` must remain valid for the lifetime of the returned object.
static std::unique_ptr<VerifiedContents> Create(
base::span<const uint8_t> public_key,
std::string_view contents);
int block_size() const { return block_size_; }
const ExtensionId& extension_id() const { return extension_id_; }
const base::Version& version() const { return version_; }
bool HasTreeHashRoot(const base::FilePath& relative_path) const;
bool TreeHashRootEquals(const base::FilePath& relative_path,
const std::string& expected) const;
bool TreeHashRootEqualsForCanonicalPath(
const CanonicalRelativePath& canonical_relative_path,
const std::string& expected) const;
// If InitFrom has not been called yet, or was used in "ignore invalid
// signature" mode, this can return false.
bool valid_signature() { return valid_signature_; }
private:
// Note: the public_key must remain valid for the lifetime of this object.
explicit VerifiedContents(base::span<const uint8_t> public_key);
// Returns the base64url-decoded "payload" field from the `contents`, if
// the signature was valid.
bool GetPayload(std::string_view contents, std::string* payload);
// The `protected_value` and `payload` arguments should be base64url encoded
// strings, and `signature_bytes` should be a byte array. See comments in the
// .cc file on GetPayload for where these come from in the overall input
// file.
bool VerifySignature(const std::string& protected_value,
const std::string& payload,
const std::string& signature_bytes);
// The public key we should use for signature verification.
base::raw_span<const uint8_t, DanglingUntriaged> public_key_;
// Indicates whether the signature was successfully validated or not.
bool valid_signature_;
// The block size used for computing the treehash root hashes.
int block_size_;
// Information about which extension these signed hashes are for.
ExtensionId extension_id_;
base::Version version_;
// The expected treehash root hashes for each file.
// For case-sensitive systems (linux/chromeos) the key is exact cased, but for
// case-insensitive systems (win/macos) the key is lower cased to support
// case-insensitive lookups.
//
// We use a multi-map here so that we can do fast lookups of paths from
// requests on case-insensitive systems (windows, mac) where the request path
// might not have the exact right capitalization. Note that this doesn't
// affect case-sensitive systems (linux, chromeos) as we use the exact cased
// keys.
// TODO(crbug.com/40334716) - we should give developers client-side warnings
// in each of those cases, and have the webstore reject the cases they can
// statically detect.
typedef std::multimap<CanonicalRelativePath, std::string> RootHashes;
RootHashes root_hashes_;
};
} // namespace extensions
#endif // EXTENSIONS_BROWSER_VERIFIED_CONTENTS_H_
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