blob: 26bc18e62af01caa0ea872e75151aea28d9e2047 (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
|
// Copyright 2021 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 "base/files/scoped_file.h"
#include <algorithm>
#include <array>
#include <atomic>
#include "base/compiler_specific.h"
#include "base/debug/stack_trace.h"
#include "base/immediate_crash.h"
#include "base/logging.h"
#include "base/strings/string_piece.h"
namespace {
// We want to avoid any kind of allocations in our close() implementation, so we
// use a fixed-size table. Given our common FD limits and the preference for new
// FD allocations to use the lowest available descriptor, this should be
// sufficient to guard most FD lifetimes. The worst case scenario if someone
// attempts to own a higher FD is that we don't track it.
const int kMaxTrackedFds = 4096;
std::atomic_bool g_is_ownership_enforced{false};
std::array<std::atomic_bool, kMaxTrackedFds> g_is_fd_owned;
NOINLINE void CrashOnFdOwnershipViolation() {
RAW_LOG(ERROR, "Crashing due to FD ownership violation:\n");
base::debug::StackTrace().Print();
IMMEDIATE_CRASH();
}
bool CanTrack(int fd) {
return fd >= 0 && fd < kMaxTrackedFds;
}
void UpdateAndCheckFdOwnership(int fd, bool owned) {
if (CanTrack(fd) && g_is_fd_owned[fd].exchange(owned) == owned &&
g_is_ownership_enforced) {
CrashOnFdOwnershipViolation();
}
}
} // namespace
namespace base {
namespace internal {
// static
void ScopedFDCloseTraits::Acquire(const ScopedFD& owner, int fd) {
UpdateAndCheckFdOwnership(fd, /*owned=*/true);
}
// static
void ScopedFDCloseTraits::Release(const ScopedFD& owner, int fd) {
UpdateAndCheckFdOwnership(fd, /*owned=*/false);
}
} // namespace internal
namespace subtle {
void EnableFDOwnershipEnforcement(bool enabled) {
g_is_ownership_enforced = enabled;
}
void ResetFDOwnership() {
std::fill(g_is_fd_owned.begin(), g_is_fd_owned.end(), false);
}
} // namespace subtle
bool IsFDOwned(int fd) {
return CanTrack(fd) && g_is_fd_owned[fd];
}
} // namespace base
extern "C" {
int __close(int);
__attribute__((visibility("default"), noinline)) int close(int fd) {
if (base::IsFDOwned(fd) && g_is_ownership_enforced)
CrashOnFdOwnershipViolation();
return __close(fd);
}
} // extern "C"
|
