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// Copyright 2020 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "sandbox/linux/syscall_broker/syscall_dispatcher.h"
#include <fcntl.h>
#include "base/check.h"
#include "base/logging.h"
#include "sandbox/linux/system_headers/linux_syscalls.h"
namespace sandbox {
namespace syscall_broker {
#if defined(MEMORY_SANITIZER)
#define BROKER_UNPOISON_STRING(x) __msan_unpoison_string(x)
#else
#define BROKER_UNPOISON_STRING(x)
#endif
int SyscallDispatcher::DefaultStatForTesting(const char* pathname,
bool follow_links,
default_stat_struct* sb) {
#if defined(__NR_fstatat64)
return Stat64(pathname, follow_links, sb);
#elif defined(__NR_newfstatat)
return Stat(pathname, follow_links, sb);
#endif
}
int SyscallDispatcher::PerformStatat(const arch_seccomp_data& args,
bool stat64) {
if (static_cast<int>(args.args[0]) != AT_FDCWD)
return -EPERM;
// Only allow the AT_SYMLINK_NOFOLLOW flag which is used by some libc
// implementations for lstat().
if ((static_cast<int>(args.args[3]) & ~AT_SYMLINK_NOFOLLOW) != 0)
return -EINVAL;
const bool follow_links =
!(static_cast<int>(args.args[3]) & AT_SYMLINK_NOFOLLOW);
if (stat64) {
return Stat64(reinterpret_cast<const char*>(args.args[1]), follow_links,
reinterpret_cast<struct kernel_stat64*>(args.args[2]));
}
return Stat(reinterpret_cast<const char*>(args.args[1]), follow_links,
reinterpret_cast<struct kernel_stat*>(args.args[2]));
}
int SyscallDispatcher::PerformUnlinkat(const arch_seccomp_data& args) {
if (static_cast<int>(args.args[0]) != AT_FDCWD)
return -EPERM;
int flags = static_cast<int>(args.args[2]);
if (flags == AT_REMOVEDIR) {
return Rmdir(reinterpret_cast<const char*>(args.args[1]));
}
if (flags != 0)
return -EPERM;
return Unlink(reinterpret_cast<const char*>(args.args[1]));
}
int SyscallDispatcher::DispatchSyscall(const arch_seccomp_data& args) {
switch (args.nr) {
#if defined(__NR_access)
case __NR_access:
return Access(reinterpret_cast<const char*>(args.args[0]),
static_cast<int>(args.args[1]));
#endif
#if defined(__NR_faccessat)
case __NR_faccessat:
#endif
#if defined(__NR_faccessat2)
case __NR_faccessat2:
#endif
#if defined(__NR_faccessat) || defined(__NR_faccessat2)
if (static_cast<int>(args.args[0]) != AT_FDCWD)
return -EPERM;
return Access(reinterpret_cast<const char*>(args.args[1]),
static_cast<int>(args.args[2]));
#endif
#if defined(__NR_mkdir)
case __NR_mkdir:
return Mkdir(reinterpret_cast<const char*>(args.args[0]),
static_cast<int>(args.args[1]));
#endif
#if defined(__NR_mkdirat)
case __NR_mkdirat:
if (static_cast<int>(args.args[0]) != AT_FDCWD)
return -EPERM;
return Mkdir(reinterpret_cast<const char*>(args.args[1]),
static_cast<int>(args.args[2]));
#endif
#if defined(__NR_open)
case __NR_open:
// http://crbug.com/372840
BROKER_UNPOISON_STRING(reinterpret_cast<const char*>(args.args[0]));
return Open(reinterpret_cast<const char*>(args.args[0]),
static_cast<int>(args.args[1]));
#endif
#if defined(__NR_openat)
case __NR_openat:
if (static_cast<int>(args.args[0]) != AT_FDCWD)
return -EPERM;
// http://crbug.com/372840
BROKER_UNPOISON_STRING(reinterpret_cast<const char*>(args.args[1]));
return Open(reinterpret_cast<const char*>(args.args[1]),
static_cast<int>(args.args[2]));
#endif
#if defined(__NR_readlink)
case __NR_readlink:
// http://crbug.com/372840
BROKER_UNPOISON_STRING(reinterpret_cast<const char*>(args.args[0]));
return Readlink(reinterpret_cast<const char*>(args.args[0]),
reinterpret_cast<char*>(args.args[1]),
static_cast<size_t>(args.args[2]));
#endif
#if defined(__NR_readlinkat)
case __NR_readlinkat:
if (static_cast<int>(args.args[0]) != AT_FDCWD)
return -EPERM;
// http://crbug.com/372840
BROKER_UNPOISON_STRING(reinterpret_cast<const char*>(args.args[1]));
return Readlink(reinterpret_cast<const char*>(args.args[1]),
reinterpret_cast<char*>(args.args[2]),
static_cast<size_t>(args.args[3]));
#endif
#if defined(__NR_rename)
case __NR_rename:
return Rename(reinterpret_cast<const char*>(args.args[0]),
reinterpret_cast<const char*>(args.args[1]));
#endif
#if defined(__NR_renameat)
case __NR_renameat:
if (static_cast<int>(args.args[0]) != AT_FDCWD ||
static_cast<int>(args.args[2]) != AT_FDCWD) {
return -EPERM;
}
return Rename(reinterpret_cast<const char*>(args.args[1]),
reinterpret_cast<const char*>(args.args[3]));
#endif
#if defined(__NR_renameat2)
case __NR_renameat2:
if (static_cast<int>(args.args[0]) != AT_FDCWD ||
static_cast<int>(args.args[2]) != AT_FDCWD) {
return -EPERM;
}
if (static_cast<int>(args.args[4]) != 0)
return -EINVAL;
return Rename(reinterpret_cast<const char*>(args.args[1]),
reinterpret_cast<const char*>(args.args[3]));
#endif
#if defined(__NR_rmdir)
case __NR_rmdir:
return Rmdir(reinterpret_cast<const char*>(args.args[0]));
#endif
#if defined(__NR_stat)
case __NR_stat:
return Stat(reinterpret_cast<const char*>(args.args[0]), true,
reinterpret_cast<struct kernel_stat*>(args.args[1]));
#endif
#if defined(__NR_stat64)
case __NR_stat64:
return Stat64(reinterpret_cast<const char*>(args.args[0]), true,
reinterpret_cast<struct kernel_stat64*>(args.args[1]));
#endif
#if defined(__NR_lstat)
case __NR_lstat:
// See https://crbug.com/847096
BROKER_UNPOISON_STRING(reinterpret_cast<const char*>(args.args[0]));
return Stat(reinterpret_cast<const char*>(args.args[0]), false,
reinterpret_cast<struct kernel_stat*>(args.args[1]));
#endif
#if defined(__NR_lstat64)
case __NR_lstat64:
// See https://crbug.com/847096
BROKER_UNPOISON_STRING(reinterpret_cast<const char*>(args.args[0]));
return Stat64(reinterpret_cast<const char*>(args.args[0]), false,
reinterpret_cast<struct kernel_stat64*>(args.args[1]));
#endif
#if defined(__NR_fstatat64)
case __NR_fstatat64:
return PerformStatat(args, /*stat64=*/true);
#endif
#if defined(__NR_newfstatat)
case __NR_newfstatat:
return PerformStatat(args, /*stat64=*/false);
#endif
#if defined(__NR_unlink)
case __NR_unlink:
return Unlink(reinterpret_cast<const char*>(args.args[0]));
#endif
#if defined(__NR_unlinkat)
case __NR_unlinkat:
return PerformUnlinkat(args);
#endif // defined(__NR_unlinkat)
#if defined(__NR_inotify_add_watch)
case __NR_inotify_add_watch:
return InotifyAddWatch(static_cast<int>(args.args[0]),
reinterpret_cast<const char*>(args.args[1]),
static_cast<uint32_t>(args.args[2]));
#endif
default:
RAW_CHECK(false);
return -ENOSYS;
}
}
} // namespace syscall_broker
} // namespace sandbox
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