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
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
|
// Copyright 2021 The Chromium Authors
// 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 <dlfcn.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"
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();
base::ImmediateCrash();
}
bool CanTrack(int fd) {
return fd >= 0 && fd < kMaxTrackedFds;
}
void UpdateAndCheckFdOwnership(int fd, bool owned) {
if (CanTrack(fd) &&
g_is_fd_owned[static_cast<size_t>(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 {
#if !defined(COMPONENT_BUILD)
void EnableFDOwnershipEnforcement(bool enabled) {
g_is_ownership_enforced = enabled;
}
#endif // !defined(COMPONENT_BUILD)
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[static_cast<size_t>(fd)];
}
} // namespace base
#if !defined(COMPONENT_BUILD)
using LibcCloseFuncPtr = int (*)(int);
// Load the libc close symbol to forward to from the close wrapper.
LibcCloseFuncPtr LoadCloseSymbol() {
#if defined(THREAD_SANITIZER)
// If TSAN is enabled use __interceptor___close first to make sure the TSAN
// wrapper gets called.
return reinterpret_cast<LibcCloseFuncPtr>(
dlsym(RTLD_DEFAULT, "__interceptor___close"));
#else
return reinterpret_cast<LibcCloseFuncPtr>(dlsym(RTLD_NEXT, "close"));
#endif
}
extern "C" {
NO_SANITIZE("cfi-icall")
__attribute__((visibility("default"), noinline)) int close(int fd) {
static LibcCloseFuncPtr libc_close = LoadCloseSymbol();
if (base::IsFDOwned(fd) && g_is_ownership_enforced) {
CrashOnFdOwnershipViolation();
}
if (libc_close == nullptr) {
RAW_LOG(ERROR, "close symbol missing\n");
base::ImmediateCrash();
}
return libc_close(fd);
}
} // extern "C"
#endif // !defined(COMPONENT_BUILD)
|
