1//===-- asan_posix.cpp ----------------------------------------------------===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9// This file is a part of AddressSanitizer, an address sanity checker.
10//
11// Posix-specific details.
12//===----------------------------------------------------------------------===//
13
14#include "sanitizer_common/sanitizer_platform.h"
15#if SANITIZER_POSIX
16
17#  include <pthread.h>
18#  include <signal.h>
19#  include <stdlib.h>
20#  include <sys/resource.h>
21#  include <sys/time.h>
22#  include <unistd.h>
23
24#  include "asan_interceptors.h"
25#  include "asan_internal.h"
26#  include "asan_mapping.h"
27#  include "asan_poisoning.h"
28#  include "asan_report.h"
29#  include "asan_stack.h"
30#  include "lsan/lsan_common.h"
31#  include "sanitizer_common/sanitizer_libc.h"
32#  include "sanitizer_common/sanitizer_posix.h"
33#  include "sanitizer_common/sanitizer_procmaps.h"
34
35namespace __asan {
36
37void AsanOnDeadlySignal(int signo, void *siginfo, void *context) {
38  StartReportDeadlySignal();
39  SignalContext sig(siginfo, context);
40  ReportDeadlySignal(sig);
41}
42
43bool PlatformUnpoisonStacks() {
44  stack_t signal_stack;
45  CHECK_EQ(0, sigaltstack(nullptr, &signal_stack));
46  uptr sigalt_bottom = (uptr)signal_stack.ss_sp;
47  uptr sigalt_top = (uptr)((char *)signal_stack.ss_sp + signal_stack.ss_size);
48  // If we're executing on the signal alternate stack AND the Linux flag
49  // SS_AUTODISARM was used, then we cannot get the signal alternate stack
50  // bounds from sigaltstack -- sigaltstack's output looks just as if no
51  // alternate stack has ever been set up.
52  // We're always unpoisoning the signal alternate stack to support jumping
53  // between the default stack and signal alternate stack.
54  if (signal_stack.ss_flags != SS_DISABLE)
55    UnpoisonStack(sigalt_bottom, sigalt_top, "sigalt");
56
57  if (signal_stack.ss_flags != SS_ONSTACK)
58    return false;
59
60  // Since we're on the signal alternate stack, we cannot find the DEFAULT
61  // stack bottom using a local variable.
62  uptr default_bottom, tls_addr, tls_size, stack_size;
63  GetThreadStackAndTls(/*main=*/false, &default_bottom, &stack_size, &tls_addr,
64                       &tls_size);
65  UnpoisonStack(default_bottom, default_bottom + stack_size, "default");
66  return true;
67}
68
69// ---------------------- TSD ---------------- {{{1
70
71#if SANITIZER_NETBSD && !ASAN_DYNAMIC
72// Thread Static Data cannot be used in early static ASan init on NetBSD.
73// Reuse the Asan TSD API for compatibility with existing code
74// with an alternative implementation.
75
76static void (*tsd_destructor)(void *tsd) = nullptr;
77
78struct tsd_key {
79  tsd_key() : key(nullptr) {}
80  ~tsd_key() {
81    CHECK(tsd_destructor);
82    if (key)
83      (*tsd_destructor)(key);
84  }
85  void *key;
86};
87
88static thread_local struct tsd_key key;
89
90void AsanTSDInit(void (*destructor)(void *tsd)) {
91  CHECK(!tsd_destructor);
92  tsd_destructor = destructor;
93}
94
95void *AsanTSDGet() {
96  CHECK(tsd_destructor);
97  return key.key;
98}
99
100void AsanTSDSet(void *tsd) {
101  CHECK(tsd_destructor);
102  CHECK(tsd);
103  CHECK(!key.key);
104  key.key = tsd;
105}
106
107void PlatformTSDDtor(void *tsd) {
108  CHECK(tsd_destructor);
109  CHECK_EQ(key.key, tsd);
110  key.key = nullptr;
111  // Make sure that signal handler can not see a stale current thread pointer.
112  atomic_signal_fence(memory_order_seq_cst);
113  AsanThread::TSDDtor(tsd);
114}
115#else
116static pthread_key_t tsd_key;
117static bool tsd_key_inited = false;
118void AsanTSDInit(void (*destructor)(void *tsd)) {
119  CHECK(!tsd_key_inited);
120  tsd_key_inited = true;
121  CHECK_EQ(0, pthread_key_create(&tsd_key, destructor));
122}
123
124void *AsanTSDGet() {
125  CHECK(tsd_key_inited);
126  return pthread_getspecific(tsd_key);
127}
128
129void AsanTSDSet(void *tsd) {
130  CHECK(tsd_key_inited);
131  pthread_setspecific(tsd_key, tsd);
132}
133
134void PlatformTSDDtor(void *tsd) {
135  AsanThreadContext *context = (AsanThreadContext *)tsd;
136  if (context->destructor_iterations > 1) {
137    context->destructor_iterations--;
138    CHECK_EQ(0, pthread_setspecific(tsd_key, tsd));
139    return;
140  }
141#    if SANITIZER_FREEBSD || SANITIZER_LINUX || SANITIZER_NETBSD || \
142        SANITIZER_SOLARIS
143  // After this point it's unsafe to execute signal handlers which may be
144  // instrumented. It's probably not just a Linux issue.
145  BlockSignals();
146#    endif
147  AsanThread::TSDDtor(tsd);
148}
149#  endif
150
151static void BeforeFork() {
152  if (CAN_SANITIZE_LEAKS) {
153    __lsan::LockGlobal();
154  }
155  // `_lsan` functions defined regardless of `CAN_SANITIZE_LEAKS` and lock the
156  // stuff we need.
157  __lsan::LockThreads();
158  __lsan::LockAllocator();
159  StackDepotLockBeforeFork();
160}
161
162static void AfterFork(bool fork_child) {
163  StackDepotUnlockAfterFork(fork_child);
164  // `_lsan` functions defined regardless of `CAN_SANITIZE_LEAKS` and unlock
165  // the stuff we need.
166  __lsan::UnlockAllocator();
167  __lsan::UnlockThreads();
168  if (CAN_SANITIZE_LEAKS) {
169    __lsan::UnlockGlobal();
170  }
171}
172
173void InstallAtForkHandler() {
174#  if SANITIZER_SOLARIS || SANITIZER_NETBSD || SANITIZER_APPLE
175  return;  // FIXME: Implement FutexWait.
176#  endif
177  pthread_atfork(
178      &BeforeFork, []() { AfterFork(/* fork_child= */ false); },
179      []() { AfterFork(/* fork_child= */ true); });
180}
181
182void InstallAtExitCheckLeaks() {
183  if (CAN_SANITIZE_LEAKS) {
184    if (common_flags()->detect_leaks && common_flags()->leak_check_at_exit) {
185      if (flags()->halt_on_error)
186        Atexit(__lsan::DoLeakCheck);
187      else
188        Atexit(__lsan::DoRecoverableLeakCheckVoid);
189    }
190  }
191}
192
193}  // namespace __asan
194
195#endif  // SANITIZER_POSIX
196