119 lines
3.1 KiB
C++
119 lines
3.1 KiB
C++
// Copyright 2021 The Chromium Authors
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#include "base/files/scoped_file.h"
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#include <dlfcn.h>
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#include <algorithm>
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#include <array>
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#include <atomic>
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#include "base/compiler_specific.h"
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#include "base/debug/stack_trace.h"
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#include "base/immediate_crash.h"
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#include "base/logging.h"
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namespace {
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// We want to avoid any kind of allocations in our close() implementation, so we
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// use a fixed-size table. Given our common FD limits and the preference for new
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// FD allocations to use the lowest available descriptor, this should be
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// sufficient to guard most FD lifetimes. The worst case scenario if someone
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// attempts to own a higher FD is that we don't track it.
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const int kMaxTrackedFds = 4096;
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std::atomic_bool g_is_ownership_enforced{false};
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std::array<std::atomic_bool, kMaxTrackedFds> g_is_fd_owned;
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NOINLINE void CrashOnFdOwnershipViolation() {
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RAW_LOG(ERROR, "Crashing due to FD ownership violation:\n");
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base::debug::StackTrace().Print();
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base::ImmediateCrash();
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}
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bool CanTrack(int fd) {
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return fd >= 0 && fd < kMaxTrackedFds;
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}
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void UpdateAndCheckFdOwnership(int fd, bool owned) {
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if (CanTrack(fd) &&
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g_is_fd_owned[static_cast<size_t>(fd)].exchange(owned) == owned &&
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g_is_ownership_enforced) {
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CrashOnFdOwnershipViolation();
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}
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}
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} // namespace
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namespace base {
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namespace internal {
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// static
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void ScopedFDCloseTraits::Acquire(const ScopedFD& owner, int fd) {
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UpdateAndCheckFdOwnership(fd, /*owned=*/true);
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}
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// static
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void ScopedFDCloseTraits::Release(const ScopedFD& owner, int fd) {
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UpdateAndCheckFdOwnership(fd, /*owned=*/false);
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}
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} // namespace internal
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namespace subtle {
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#if !defined(COMPONENT_BUILD)
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void EnableFDOwnershipEnforcement(bool enabled) {
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g_is_ownership_enforced = enabled;
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}
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#endif // !defined(COMPONENT_BUILD)
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void ResetFDOwnership() {
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std::fill(g_is_fd_owned.begin(), g_is_fd_owned.end(), false);
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}
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} // namespace subtle
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bool IsFDOwned(int fd) {
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return CanTrack(fd) && g_is_fd_owned[static_cast<size_t>(fd)];
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}
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} // namespace base
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#ifndef OPENWRT_BUILD_STATIC
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#if !defined(COMPONENT_BUILD)
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using LibcCloseFuncPtr = int (*)(int);
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// Load the libc close symbol to forward to from the close wrapper.
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LibcCloseFuncPtr LoadCloseSymbol() {
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#if defined(THREAD_SANITIZER)
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// If TSAN is enabled use __interceptor___close first to make sure the TSAN
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// wrapper gets called.
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return reinterpret_cast<LibcCloseFuncPtr>(
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dlsym(RTLD_DEFAULT, "__interceptor___close"));
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#else
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return reinterpret_cast<LibcCloseFuncPtr>(dlsym(RTLD_NEXT, "close"));
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#endif
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}
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extern "C" {
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NO_SANITIZE("cfi-icall")
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__attribute__((visibility("default"), noinline)) int close(int fd) {
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static LibcCloseFuncPtr libc_close = LoadCloseSymbol();
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if (base::IsFDOwned(fd) && g_is_ownership_enforced) {
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CrashOnFdOwnershipViolation();
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}
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if (libc_close == nullptr) {
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RAW_LOG(ERROR, "close symbol missing\n");
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base::ImmediateCrash();
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}
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return libc_close(fd);
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}
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} // extern "C"
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#endif // !defined(COMPONENT_BUILD)
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#endif // OPENWRT_BUILD_STATIC
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