1 //===-- sanitizer_linux.cc ------------------------------------------------===//
3 // This file is distributed under the University of Illinois Open Source
4 // License. See LICENSE.TXT for details.
6 //===----------------------------------------------------------------------===//
8 // This file is shared between AddressSanitizer and ThreadSanitizer
9 // run-time libraries and implements linux-specific functions from
11 //===----------------------------------------------------------------------===//
14 #include "sanitizer_common.h"
15 #include "sanitizer_internal_defs.h"
16 #include "sanitizer_libc.h"
17 #include "sanitizer_mutex.h"
18 #include "sanitizer_placement_new.h"
19 #include "sanitizer_procmaps.h"
20 #include "sanitizer_stacktrace.h"
26 #include <sys/resource.h>
28 #include <sys/syscall.h>
30 #include <sys/types.h>
31 #include <sys/prctl.h>
36 // <linux/futex.h> is broken on some linux distributions.
37 const int FUTEX_WAIT = 0;
38 const int FUTEX_WAKE = 1;
40 // Are we using 32-bit or 64-bit syscalls?
41 // x32 (which defines __x86_64__) has SANITIZER_WORDSIZE == 32
42 // but it still needs to use 64-bit syscalls.
43 #if defined(__x86_64__) || SANITIZER_WORDSIZE == 64
44 # define SANITIZER_LINUX_USES_64BIT_SYSCALLS 1
46 # define SANITIZER_LINUX_USES_64BIT_SYSCALLS 0
49 namespace __sanitizer {
51 // --------------- sanitizer_libc.h
52 void *internal_mmap(void *addr, uptr length, int prot, int flags,
54 #if SANITIZER_LINUX_USES_64BIT_SYSCALLS
55 return (void *)syscall(__NR_mmap, addr, length, prot, flags, fd, offset);
57 return (void *)syscall(__NR_mmap2, addr, length, prot, flags, fd, offset);
61 int internal_munmap(void *addr, uptr length) {
62 return syscall(__NR_munmap, addr, length);
65 int internal_close(fd_t fd) {
66 return syscall(__NR_close, fd);
69 fd_t internal_open(const char *filename, int flags) {
70 return syscall(__NR_open, filename, flags);
73 fd_t internal_open(const char *filename, int flags, u32 mode) {
74 return syscall(__NR_open, filename, flags, mode);
77 fd_t OpenFile(const char *filename, bool write) {
78 return internal_open(filename,
79 write ? O_WRONLY | O_CREAT /*| O_CLOEXEC*/ : O_RDONLY, 0660);
82 uptr internal_read(fd_t fd, void *buf, uptr count) {
84 HANDLE_EINTR(res, (sptr)syscall(__NR_read, fd, buf, count));
88 uptr internal_write(fd_t fd, const void *buf, uptr count) {
90 HANDLE_EINTR(res, (sptr)syscall(__NR_write, fd, buf, count));
94 int internal_stat(const char *path, void *buf) {
95 #if SANITIZER_LINUX_USES_64BIT_SYSCALLS
96 return syscall(__NR_stat, path, buf);
98 return syscall(__NR_stat64, path, buf);
102 int internal_lstat(const char *path, void *buf) {
103 #if SANITIZER_LINUX_USES_64BIT_SYSCALLS
104 return syscall(__NR_lstat, path, buf);
106 return syscall(__NR_lstat64, path, buf);
110 int internal_fstat(fd_t fd, void *buf) {
111 #if SANITIZER_LINUX_USES_64BIT_SYSCALLS
112 return syscall(__NR_fstat, fd, buf);
114 return syscall(__NR_fstat64, fd, buf);
118 uptr internal_filesize(fd_t fd) {
119 #if SANITIZER_LINUX_USES_64BIT_SYSCALLS
124 if (internal_fstat(fd, &st))
126 return (uptr)st.st_size;
129 int internal_dup2(int oldfd, int newfd) {
130 return syscall(__NR_dup2, oldfd, newfd);
133 uptr internal_readlink(const char *path, char *buf, uptr bufsize) {
134 return (uptr)syscall(__NR_readlink, path, buf, bufsize);
137 int internal_sched_yield() {
138 return syscall(__NR_sched_yield);
141 void internal__exit(int exitcode) {
142 syscall(__NR_exit_group, exitcode);
143 Die(); // Unreachable.
146 // ----------------- sanitizer_common.h
147 bool FileExists(const char *filename) {
148 #if SANITIZER_LINUX_USES_64BIT_SYSCALLS
150 if (syscall(__NR_stat, filename, &st))
154 if (syscall(__NR_stat64, filename, &st))
157 // Sanity check: filename is a regular file.
158 return S_ISREG(st.st_mode);
162 return syscall(__NR_gettid);
165 void GetThreadStackTopAndBottom(bool at_initialization, uptr *stack_top,
166 uptr *stack_bottom) {
167 static const uptr kMaxThreadStackSize = 256 * (1 << 20); // 256M
170 if (at_initialization) {
171 // This is the main thread. Libpthread may not be initialized yet.
173 CHECK_EQ(getrlimit(RLIMIT_STACK, &rl), 0);
175 // Find the mapping that contains a stack variable.
176 MemoryMappingLayout proc_maps;
177 uptr start, end, offset;
179 while (proc_maps.Next(&start, &end, &offset, 0, 0)) {
184 CHECK((uptr)&rl >= start && (uptr)&rl < end);
186 // Get stacksize from rlimit, but clip it so that it does not overlap
187 // with other mappings.
188 uptr stacksize = rl.rlim_cur;
189 if (stacksize > end - prev_end)
190 stacksize = end - prev_end;
191 // When running with unlimited stack size, we still want to set some limit.
192 // The unlimited stack size is caused by 'ulimit -s unlimited'.
193 // Also, for some reason, GNU make spawns subprocesses with unlimited stack.
194 if (stacksize > kMaxThreadStackSize)
195 stacksize = kMaxThreadStackSize;
197 *stack_bottom = end - stacksize;
201 CHECK_EQ(pthread_getattr_np(pthread_self(), &attr), 0);
204 pthread_attr_getstack(&attr, &stackaddr, (size_t*)&stacksize);
205 pthread_attr_destroy(&attr);
207 *stack_top = (uptr)stackaddr + stacksize;
208 *stack_bottom = (uptr)stackaddr;
209 CHECK(stacksize < kMaxThreadStackSize); // Sanity check.
212 // Like getenv, but reads env directly from /proc and does not use libc.
213 // This function should be called first inside __asan_init.
214 const char *GetEnv(const char *name) {
215 static char *environ;
221 len = ReadFileToBuffer("/proc/self/environ",
222 &environ, &environ_size, 1 << 26);
224 if (!environ || len == 0) return 0;
225 uptr namelen = internal_strlen(name);
226 const char *p = environ;
227 while (*p != '\0') { // will happen at the \0\0 that terminates the buffer
228 // proc file has the format NAME=value\0NAME=value\0NAME=value\0...
230 (char*)internal_memchr(p, '\0', len - (p - environ));
231 if (endp == 0) // this entry isn't NUL terminated
233 else if (!internal_memcmp(p, name, namelen) && p[namelen] == '=') // Match.
234 return p + namelen + 1; // point after =
237 return 0; // Not found.
243 extern void *__libc_stack_end;
246 static void GetArgsAndEnv(char ***argv, char ***envp) {
247 uptr *stack_end = (uptr *)__libc_stack_end;
248 int argc = *stack_end;
249 *argv = (char**)(stack_end + 1);
250 *envp = (char**)(stack_end + argc + 2);
255 static void ReadNullSepFileToArray(const char *path, char ***arr,
259 *arr = (char **)MmapOrDie(arr_size * sizeof(char *), "NullSepFileArray");
260 ReadFileToBuffer(path, &buff, &buff_size, 1024 * 1024);
263 for (count = 1, i = 1; ; i++) {
265 if (buff[i+1] == 0) break;
266 (*arr)[count] = &buff[i+1];
267 CHECK_LE(count, arr_size - 1); // FIXME: make this more flexible.
274 static void GetArgsAndEnv(char ***argv, char ***envp) {
275 static const int kMaxArgv = 2000, kMaxEnvp = 2000;
276 ReadNullSepFileToArray("/proc/self/cmdline", argv, kMaxArgv);
277 ReadNullSepFileToArray("/proc/self/environ", envp, kMaxEnvp);
284 GetArgsAndEnv(&argv, &envp);
285 execve("/proc/self/exe", argv, envp);
286 Printf("execve failed, errno %d\n", errno);
290 void PrepareForSandboxing() {
291 // Some kinds of sandboxes may forbid filesystem access, so we won't be able
292 // to read the file mappings from /proc/self/maps. Luckily, neither the
293 // process will be able to load additional libraries, so it's fine to use the
295 MemoryMappingLayout::CacheMemoryMappings();
298 // ----------------- sanitizer_procmaps.h
299 // Linker initialized.
300 ProcSelfMapsBuff MemoryMappingLayout::cached_proc_self_maps_;
301 StaticSpinMutex MemoryMappingLayout::cache_lock_; // Linker initialized.
303 MemoryMappingLayout::MemoryMappingLayout() {
304 proc_self_maps_.len =
305 ReadFileToBuffer("/proc/self/maps", &proc_self_maps_.data,
306 &proc_self_maps_.mmaped_size, 1 << 26);
307 if (proc_self_maps_.mmaped_size == 0) {
309 CHECK_GT(proc_self_maps_.len, 0);
311 // internal_write(2, proc_self_maps_.data, proc_self_maps_.len);
313 // FIXME: in the future we may want to cache the mappings on demand only.
314 CacheMemoryMappings();
317 MemoryMappingLayout::~MemoryMappingLayout() {
318 // Only unmap the buffer if it is different from the cached one. Otherwise
319 // it will be unmapped when the cache is refreshed.
320 if (proc_self_maps_.data != cached_proc_self_maps_.data) {
321 UnmapOrDie(proc_self_maps_.data, proc_self_maps_.mmaped_size);
325 void MemoryMappingLayout::Reset() {
326 current_ = proc_self_maps_.data;
330 void MemoryMappingLayout::CacheMemoryMappings() {
331 SpinMutexLock l(&cache_lock_);
332 // Don't invalidate the cache if the mappings are unavailable.
333 ProcSelfMapsBuff old_proc_self_maps;
334 old_proc_self_maps = cached_proc_self_maps_;
335 cached_proc_self_maps_.len =
336 ReadFileToBuffer("/proc/self/maps", &cached_proc_self_maps_.data,
337 &cached_proc_self_maps_.mmaped_size, 1 << 26);
338 if (cached_proc_self_maps_.mmaped_size == 0) {
339 cached_proc_self_maps_ = old_proc_self_maps;
341 if (old_proc_self_maps.mmaped_size) {
342 UnmapOrDie(old_proc_self_maps.data,
343 old_proc_self_maps.mmaped_size);
348 void MemoryMappingLayout::LoadFromCache() {
349 SpinMutexLock l(&cache_lock_);
350 if (cached_proc_self_maps_.data) {
351 proc_self_maps_ = cached_proc_self_maps_;
355 // Parse a hex value in str and update str.
356 static uptr ParseHex(char **str) {
359 for (s = *str; ; s++) {
362 if (c >= '0' && c <= '9')
364 else if (c >= 'a' && c <= 'f')
366 else if (c >= 'A' && c <= 'F')
376 static bool IsOnOf(char c, char c1, char c2) {
377 return c == c1 || c == c2;
380 static bool IsDecimal(char c) {
381 return c >= '0' && c <= '9';
384 bool MemoryMappingLayout::Next(uptr *start, uptr *end, uptr *offset,
385 char filename[], uptr filename_size) {
386 char *last = proc_self_maps_.data + proc_self_maps_.len;
387 if (current_ >= last) return false;
389 if (!start) start = &dummy;
390 if (!end) end = &dummy;
391 if (!offset) offset = &dummy;
392 char *next_line = (char*)internal_memchr(current_, '\n', last - current_);
395 // Example: 08048000-08056000 r-xp 00000000 03:0c 64593 /foo/bar
396 *start = ParseHex(¤t_);
397 CHECK_EQ(*current_++, '-');
398 *end = ParseHex(¤t_);
399 CHECK_EQ(*current_++, ' ');
400 CHECK(IsOnOf(*current_++, '-', 'r'));
401 CHECK(IsOnOf(*current_++, '-', 'w'));
402 CHECK(IsOnOf(*current_++, '-', 'x'));
403 CHECK(IsOnOf(*current_++, 's', 'p'));
404 CHECK_EQ(*current_++, ' ');
405 *offset = ParseHex(¤t_);
406 CHECK_EQ(*current_++, ' ');
408 CHECK_EQ(*current_++, ':');
410 CHECK_EQ(*current_++, ' ');
411 while (IsDecimal(*current_))
413 CHECK_EQ(*current_++, ' ');
415 while (current_ < next_line && *current_ == ' ')
417 // Fill in the filename.
419 while (current_ < next_line) {
420 if (filename && i < filename_size - 1)
421 filename[i++] = *current_;
424 if (filename && i < filename_size)
426 current_ = next_line + 1;
430 // Gets the object name and the offset by walking MemoryMappingLayout.
431 bool MemoryMappingLayout::GetObjectNameAndOffset(uptr addr, uptr *offset,
433 uptr filename_size) {
434 return IterateForObjectNameAndOffset(addr, offset, filename, filename_size);
437 bool SanitizerSetThreadName(const char *name) {
439 return 0 == prctl(PR_SET_NAME, (unsigned long)name, 0, 0, 0); // NOLINT
445 bool SanitizerGetThreadName(char *name, int max_len) {
448 if (prctl(PR_GET_NAME, (unsigned long)buff, 0, 0, 0)) // NOLINT
450 internal_strncpy(name, buff, max_len);
459 //------------------------- SlowUnwindStack -----------------------------------
461 #define UNWIND_STOP _URC_END_OF_STACK
462 #define UNWIND_CONTINUE _URC_NO_REASON
464 #define UNWIND_STOP _URC_NORMAL_STOP
465 #define UNWIND_CONTINUE _URC_NO_REASON
468 uptr Unwind_GetIP(struct _Unwind_Context *ctx) {
471 _Unwind_VRS_Result res = _Unwind_VRS_Get(ctx, _UVRSC_CORE,
472 15 /* r15 = PC */, _UVRSD_UINT32, &val);
473 CHECK(res == _UVRSR_OK && "_Unwind_VRS_Get failed");
474 // Clear the Thumb bit.
475 return val & ~(uptr)1;
477 return _Unwind_GetIP(ctx);
481 _Unwind_Reason_Code Unwind_Trace(struct _Unwind_Context *ctx, void *param) {
482 StackTrace *b = (StackTrace*)param;
483 CHECK(b->size < b->max_size);
484 uptr pc = Unwind_GetIP(ctx);
485 b->trace[b->size++] = pc;
486 if (b->size == b->max_size) return UNWIND_STOP;
487 return UNWIND_CONTINUE;
490 static bool MatchPc(uptr cur_pc, uptr trace_pc) {
491 return cur_pc - trace_pc <= 64 || trace_pc - cur_pc <= 64;
494 void StackTrace::SlowUnwindStack(uptr pc, uptr max_depth) {
496 this->max_size = max_depth;
498 _Unwind_Backtrace(Unwind_Trace, this);
499 // We need to pop a few frames so that pc is on top.
500 // trace[0] belongs to the current function so we always pop it.
502 /**/ if (size > 1 && MatchPc(pc, trace[1])) to_pop = 1;
503 else if (size > 2 && MatchPc(pc, trace[2])) to_pop = 2;
504 else if (size > 3 && MatchPc(pc, trace[3])) to_pop = 3;
505 else if (size > 4 && MatchPc(pc, trace[4])) to_pop = 4;
506 else if (size > 5 && MatchPc(pc, trace[5])) to_pop = 5;
507 this->PopStackFrames(to_pop);
512 #endif // #ifndef SANITIZER_GO
520 BlockingMutex::BlockingMutex(LinkerInitialized) {
524 void BlockingMutex::Lock() {
525 atomic_uint32_t *m = reinterpret_cast<atomic_uint32_t *>(&opaque_storage_);
526 if (atomic_exchange(m, MtxLocked, memory_order_acquire) == MtxUnlocked)
528 while (atomic_exchange(m, MtxSleeping, memory_order_acquire) != MtxUnlocked)
529 syscall(__NR_futex, m, FUTEX_WAIT, MtxSleeping, 0, 0, 0);
532 void BlockingMutex::Unlock() {
533 atomic_uint32_t *m = reinterpret_cast<atomic_uint32_t *>(&opaque_storage_);
534 u32 v = atomic_exchange(m, MtxUnlocked, memory_order_relaxed);
535 CHECK_NE(v, MtxUnlocked);
536 if (v == MtxSleeping)
537 syscall(__NR_futex, m, FUTEX_WAKE, 1, 0, 0, 0);
540 } // namespace __sanitizer