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// Copyright 2014 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 <sys/stat.h>
#include <sys/types.h>
#include <unistd.h>
#include "base/macros.h"
#include "sandbox/linux/syscall_broker/broker_channel.h"
#include "sandbox/linux/syscall_broker/broker_command.h"
#include "sandbox/linux/syscall_broker/syscall_dispatcher.h"
#include "sandbox/sandbox_export.h"
namespace sandbox {
namespace syscall_broker {
class BrokerPermissionList;
// This class can be embedded in a sandboxed process and can be
// used to perform certain system calls in another, presumably
// non-sandboxed process (which embeds BrokerHost).
// A key feature of this class is the ability to use some of its methods in a
// thread-safe and async-signal safe way. The goal is to be able to use it to
// replace the open() or access() system calls happening anywhere in a process
// (as allowed for instance by seccomp-bpf's SIGSYS mechanism).
class SANDBOX_EXPORT BrokerClient : public SyscallDispatcher {
// Handler to be used with a bpf_dsl Trap() function to forward system calls
// to the methods below.
static intptr_t SIGSYS_Handler(const arch_seccomp_data& args,
void* aux_broker_process);
// |policy| needs to match the policy used by BrokerHost. This
// allows to predict some of the requests which will be denied
// and save an IPC round trip.
// |ipc_channel| needs to be a suitable SOCK_SEQPACKET unix socket.
// |fast_check_in_client| should be set to true and
BrokerClient(const BrokerPermissionList& policy,
BrokerChannel::EndPoint ipc_channel,
const BrokerCommandSet& allowed_command_set,
bool fast_check_in_client);
~BrokerClient() override;
// Get the file descriptor used for IPC.
int GetIPCDescriptorForTesting() const { return ipc_channel_.get(); }
// The following public methods can be used in place of the equivalently
// name system calls. They all return -errno on errors. They are all async
// signal safe so they may be called from a SIGSYS trap handler.
// SyscallDispatcher implementation:
int Access(const char* pathname, int mode) const override;
int Mkdir(const char* path, int mode) const override;
int Open(const char* pathname, int flags) const override;
int Readlink(const char* path, char* buf, size_t bufsize) const override;
int Rename(const char* oldpath, const char* newpath) const override;
int Rmdir(const char* path) const override;
int Stat(const char* pathname,
bool follow_links,
struct stat* sb) const override;
int Stat64(const char* pathname,
bool follow_links,
struct stat64* sb) const override;
int Unlink(const char* unlink) const override;
int PathOnlySyscall(BrokerCommand syscall_type, const char* pathname) const;
int PathAndFlagsSyscall(BrokerCommand syscall_type,
const char* pathname,
int flags) const;
int PathAndFlagsSyscallReturningFD(BrokerCommand syscall_type,
const char* pathname,
int flags) const;
int StatFamilySyscall(BrokerCommand syscall_type,
const char* pathname,
bool follow_links,
void* result_ptr,
size_t expected_result_size) const;
const BrokerPermissionList& broker_permission_list_;
const BrokerChannel::EndPoint ipc_channel_;
const BrokerCommandSet allowed_command_set_;
const bool fast_check_in_client_; // Whether to forward a request that we
// know will be denied to the broker. (Used
// for tests).
} // namespace syscall_broker
} // namespace sandbox