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// Copyright 2020 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.
#ifndef SANDBOX_LINUX_SYSCALL_BROKER_SYSCALL_DISPATCHER_H_
#define SANDBOX_LINUX_SYSCALL_BROKER_SYSCALL_DISPATCHER_H_
#include <sys/stat.h>
#include <cstddef>
#include "sandbox/linux/system_headers/linux_seccomp.h"
#include "sandbox/linux/system_headers/linux_stat.h"
#include "sandbox/sandbox_export.h"
namespace sandbox {
namespace syscall_broker {
// An abstract class that defines all the system calls we perform for the
// sandboxed process.
class SANDBOX_EXPORT SyscallDispatcher {
public:
// Emulates access()/faccessat().
// X_OK will always return an error in practice since the broker process
// doesn't support execute permissions.
virtual int Access(const char* pathname, int mode) const = 0;
// Emulates mkdir()/mkdirat.
virtual int Mkdir(const char* path, int mode) const = 0;
// Emulates open()/openat().
// The implementation only supports certain white listed flags and will
// return -EPERM on other flags.
virtual int Open(const char* pathname, int flags) const = 0;
// Emulates readlink()/readlinkat().
virtual int Readlink(const char* path, char* buf, size_t bufsize) const = 0;
// Emulates rename()/renameat()/renameat2().
virtual int Rename(const char* oldpath, const char* newpath) const = 0;
// Emulates rmdir().
virtual int Rmdir(const char* path) const = 0;
// Emulates stat()/stat64()/lstat()/lstat64()/fstatat()/newfstatat().
// Stat64 is only available on 32-bit systems.
virtual int Stat(const char* pathname,
bool follow_links,
struct kernel_stat* sb) const = 0;
virtual int Stat64(const char* pathname,
bool follow_links,
struct kernel_stat64* sb) const = 0;
// Emulates unlink()/unlinkat().
virtual int Unlink(const char* unlink) const = 0;
// Different architectures use a different syscall from the stat family by
// default in glibc. E.g. 32-bit systems use *stat*64() and fill out struct
// kernel_stat64, whereas 64-bit systems use *stat*() and fill out struct
// kernel_stat. Some tests want to call the SyscallDispatcher directly, and
// should be using the default stat in order to test against glibc.
int DefaultStatForTesting(const char* pathname,
bool follow_links,
default_stat_struct* sb);
// Validates the args passed to a *statat*() syscall and performs the syscall
// using Stat(), or on 32-bit systems it uses Stat64() for the *statat64()
// syscalls.
int PerformStatat(const arch_seccomp_data& args, bool stat64);
// Validates the args passed to an unlinkat() syscall and performs the syscall
// using either Unlink() or Rmdir().
int PerformUnlinkat(const arch_seccomp_data& args);
// Reads the syscall number and arguments, imposes some policy (e.g. the *at()
// system calls must only allow AT_FDCWD as the first argument), and
// dispatches to the correct method from above.
// Async-signal-safe since this might be called in a signal handler.
int DispatchSyscall(const arch_seccomp_data& args);
protected:
virtual ~SyscallDispatcher() = default;
};
} // namespace syscall_broker
} // namespace sandbox
#endif // SANDBOX_LINUX_SYSCALL_BROKER_SYSCALL_DISPATCHER_H_
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