libsanitizer/sanitizer_common/sanitizer_linux.cc

   1 //===-- sanitizer_linux.cc ------------------------------------------------===//
   2 //
   3 // This file is distributed under the University of Illinois Open Source
   4 // License. See LICENSE.TXT for details.
   5 //
   6 //===----------------------------------------------------------------------===//
   7 //
   8 // This file is shared between AddressSanitizer and ThreadSanitizer
   9 // run-time libraries and implements linux-specific functions from
  10 // sanitizer_libc.h.
  11 //===----------------------------------------------------------------------===//
  12 #ifdef __linux__
  13
  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"
  21
  22 #include <fcntl.h>
  23 #include <pthread.h>
  24 #include <sched.h>
  25 #include <sys/mman.h>
  26 #include <sys/resource.h>
  27 #include <sys/stat.h>
  28 #include <sys/syscall.h>
  29 #include <sys/time.h>
  30 #include <sys/types.h>
  31 #include <sys/prctl.h>
  32 #include <unistd.h>
  33 #include <unwind.h>
  34 #include <errno.h>
  35
  36 // <linux/futex.h> is broken on some linux distributions.
  37 const int FUTEX_WAIT = 0;
  38 const int FUTEX_WAKE = 1;
  39
  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
  45 #else
  46 # define SANITIZER_LINUX_USES_64BIT_SYSCALLS 0
  47 #endif
  48
  49 namespace __sanitizer {
  50
  51 // --------------- sanitizer_libc.h
  52 void *internal_mmap(void *addr, uptr length, int prot, int flags,
  53                     int fd, u64 offset) {
  54 #if SANITIZER_LINUX_USES_64BIT_SYSCALLS
  55   return (void *)syscall(__NR_mmap, addr, length, prot, flags, fd, offset);
  56 #else
  57   return (void *)syscall(__NR_mmap2, addr, length, prot, flags, fd, offset);
  58 #endif
  59 }
  60
  61 int internal_munmap(void *addr, uptr length) {
  62   return syscall(__NR_munmap, addr, length);
  63 }
  64
  65 int internal_close(fd_t fd) {
  66   return syscall(__NR_close, fd);
  67 }
  68
  69 fd_t internal_open(const char *filename, int flags) {
  70   return syscall(__NR_open, filename, flags);
  71 }
  72
  73 fd_t internal_open(const char *filename, int flags, u32 mode) {
  74   return syscall(__NR_open, filename, flags, mode);
  75 }
  76
  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);
  80 }
  81
  82 uptr internal_read(fd_t fd, void *buf, uptr count) {
  83   sptr res;
  84   HANDLE_EINTR(res, (sptr)syscall(__NR_read, fd, buf, count));
  85   return res;
  86 }
  87
  88 uptr internal_write(fd_t fd, const void *buf, uptr count) {
  89   sptr res;
  90   HANDLE_EINTR(res, (sptr)syscall(__NR_write, fd, buf, count));
  91   return res;
  92 }
  93
  94 int internal_stat(const char *path, void *buf) {
  95 #if SANITIZER_LINUX_USES_64BIT_SYSCALLS
  96   return syscall(__NR_stat, path, buf);
  97 #else
  98   return syscall(__NR_stat64, path, buf);
  99 #endif
 100 }
 101
 102 int internal_lstat(const char *path, void *buf) {
 103 #if SANITIZER_LINUX_USES_64BIT_SYSCALLS
 104   return syscall(__NR_lstat, path, buf);
 105 #else
 106   return syscall(__NR_lstat64, path, buf);
 107 #endif
 108 }
 109
 110 int internal_fstat(fd_t fd, void *buf) {
 111 #if SANITIZER_LINUX_USES_64BIT_SYSCALLS
 112   return syscall(__NR_fstat, fd, buf);
 113 #else
 114   return syscall(__NR_fstat64, fd, buf);
 115 #endif
 116 }
 117
 118 uptr internal_filesize(fd_t fd) {
 119 #if SANITIZER_LINUX_USES_64BIT_SYSCALLS
 120   struct stat st;
 121 #else
 122   struct stat64 st;
 123 #endif
 124   if (internal_fstat(fd, &st))
 125     return -1;
 126   return (uptr)st.st_size;
 127 }
 128
 129 int internal_dup2(int oldfd, int newfd) {
 130   return syscall(__NR_dup2, oldfd, newfd);
 131 }
 132
 133 uptr internal_readlink(const char *path, char *buf, uptr bufsize) {
 134   return (uptr)syscall(__NR_readlink, path, buf, bufsize);
 135 }
 136
 137 int internal_sched_yield() {
 138   return syscall(__NR_sched_yield);
 139 }
 140
 141 void internal__exit(int exitcode) {
 142   syscall(__NR_exit_group, exitcode);
 143   Die();  // Unreachable.
 144 }
 145
 146 // ----------------- sanitizer_common.h
 147 bool FileExists(const char *filename) {
 148 #if SANITIZER_LINUX_USES_64BIT_SYSCALLS
 149   struct stat st;
 150   if (syscall(__NR_stat, filename, &st))
 151     return false;
 152 #else
 153   struct stat64 st;
 154   if (syscall(__NR_stat64, filename, &st))
 155     return false;
 156 #endif
 157   // Sanity check: filename is a regular file.
 158   return S_ISREG(st.st_mode);
 159 }
 160
 161 uptr GetTid() {
 162   return syscall(__NR_gettid);
 163 }
 164
 165 void GetThreadStackTopAndBottom(bool at_initialization, uptr *stack_top,
 166                                 uptr *stack_bottom) {
 167   static const uptr kMaxThreadStackSize = 256 * (1 << 20);  // 256M
 168   CHECK(stack_top);
 169   CHECK(stack_bottom);
 170   if (at_initialization) {
 171     // This is the main thread. Libpthread may not be initialized yet.
 172     struct rlimit rl;
 173     CHECK_EQ(getrlimit(RLIMIT_STACK, &rl), 0);
 174
 175     // Find the mapping that contains a stack variable.
 176     MemoryMappingLayout proc_maps;
 177     uptr start, end, offset;
 178     uptr prev_end = 0;
 179     while (proc_maps.Next(&start, &end, &offset, 0, 0)) {
 180       if ((uptr)&rl < end)
 181         break;
 182       prev_end = end;
 183     }
 184     CHECK((uptr)&rl >= start && (uptr)&rl < end);
 185
 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;
 196     *stack_top = end;
 197     *stack_bottom = end - stacksize;
 198     return;
 199   }
 200   pthread_attr_t attr;
 201   CHECK_EQ(pthread_getattr_np(pthread_self(), &attr), 0);
 202   uptr stacksize = 0;
 203   void *stackaddr = 0;
 204   pthread_attr_getstack(&attr, &stackaddr, (size_t*)&stacksize);
 205   pthread_attr_destroy(&attr);
 206
 207   *stack_top = (uptr)stackaddr + stacksize;
 208   *stack_bottom = (uptr)stackaddr;
 209   CHECK(stacksize < kMaxThreadStackSize);  // Sanity check.
 210 }
 211
 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;
 216   static uptr len;
 217   static bool inited;
 218   if (!inited) {
 219     inited = true;
 220     uptr environ_size;
 221     len = ReadFileToBuffer("/proc/self/environ",
 222                            &environ, &environ_size, 1 << 26);
 223   }
 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...
 229     const char* endp =
 230         (char*)internal_memchr(p, '\0', len - (p - environ));
 231     if (endp == 0)  // this entry isn't NUL terminated
 232       return 0;
 233     else if (!internal_memcmp(p, name, namelen) && p[namelen] == '=')  // Match.
 234       return p + namelen + 1;  // point after =
 235     p = endp + 1;
 236   }
 237   return 0;  // Not found.
 238 }
 239
 240 #ifdef __GLIBC__
 241
 242 extern "C" {
 243   extern void *__libc_stack_end;
 244 }
 245
 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);
 251 }
 252
 253 #else  // __GLIBC__
 254
 255 static void ReadNullSepFileToArray(const char *path, char ***arr,
 256                                    int arr_size) {
 257   char *buff;
 258   uptr buff_size = 0;
 259   *arr = (char **)MmapOrDie(arr_size * sizeof(char *), "NullSepFileArray");
 260   ReadFileToBuffer(path, &buff, &buff_size, 1024 * 1024);
 261   (*arr)[0] = buff;
 262   int count, i;
 263   for (count = 1, i = 1; ; i++) {
 264     if (buff[i] == 0) {
 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.
 268       count++;
 269     }
 270   }
 271   (*arr)[count] = 0;
 272 }
 273
 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);
 278 }
 279
 280 #endif  // __GLIBC__
 281
 282 void ReExec() {
 283   char **argv, **envp;
 284   GetArgsAndEnv(&argv, &envp);
 285   execve("/proc/self/exe", argv, envp);
 286   Printf("execve failed, errno %d\n", errno);
 287   Die();
 288 }
 289
 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
 294   // cached mappings.
 295   MemoryMappingLayout::CacheMemoryMappings();
 296 }
 297
 298 // ----------------- sanitizer_procmaps.h
 299 // Linker initialized.
 300 ProcSelfMapsBuff MemoryMappingLayout::cached_proc_self_maps_;
 301 StaticSpinMutex MemoryMappingLayout::cache_lock_;  // Linker initialized.
 302
 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) {
 308     LoadFromCache();
 309     CHECK_GT(proc_self_maps_.len, 0);
 310   }
 311   // internal_write(2, proc_self_maps_.data, proc_self_maps_.len);
 312   Reset();
 313   // FIXME: in the future we may want to cache the mappings on demand only.
 314   CacheMemoryMappings();
 315 }
 316
 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);
 322   }
 323 }
 324
 325 void MemoryMappingLayout::Reset() {
 326   current_ = proc_self_maps_.data;
 327 }
 328
 329 // static
 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;
 340   } else {
 341     if (old_proc_self_maps.mmaped_size) {
 342       UnmapOrDie(old_proc_self_maps.data,
 343                  old_proc_self_maps.mmaped_size);
 344     }
 345   }
 346 }
 347
 348 void MemoryMappingLayout::LoadFromCache() {
 349   SpinMutexLock l(&cache_lock_);
 350   if (cached_proc_self_maps_.data) {
 351     proc_self_maps_ = cached_proc_self_maps_;
 352   }
 353 }
 354
 355 // Parse a hex value in str and update str.
 356 static uptr ParseHex(char **str) {
 357   uptr x = 0;
 358   char *s;
 359   for (s = *str; ; s++) {
 360     char c = *s;
 361     uptr v = 0;
 362     if (c >= '0' && c <= '9')
 363       v = c - '0';
 364     else if (c >= 'a' && c <= 'f')
 365       v = c - 'a' + 10;
 366     else if (c >= 'A' && c <= 'F')
 367       v = c - 'A' + 10;
 368     else
 369       break;
 370     x = x * 16 + v;
 371   }
 372   *str = s;
 373   return x;
 374 }
 375
 376 static bool IsOnOf(char c, char c1, char c2) {
 377   return c == c1 || c == c2;
 378 }
 379
 380 static bool IsDecimal(char c) {
 381   return c >= '0' && c <= '9';
 382 }
 383
 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;
 388   uptr dummy;
 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_);
 393   if (next_line == 0)
 394     next_line = last;
 395   // Example: 08048000-08056000 r-xp 00000000 03:0c 64593   /foo/bar
 396   *start = ParseHex(&current_);
 397   CHECK_EQ(*current_++, '-');
 398   *end = ParseHex(&current_);
 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(&current_);
 406   CHECK_EQ(*current_++, ' ');
 407   ParseHex(&current_);
 408   CHECK_EQ(*current_++, ':');
 409   ParseHex(&current_);
 410   CHECK_EQ(*current_++, ' ');
 411   while (IsDecimal(*current_))
 412     current_++;
 413   CHECK_EQ(*current_++, ' ');
 414   // Skip spaces.
 415   while (current_ < next_line && *current_ == ' ')
 416     current_++;
 417   // Fill in the filename.
 418   uptr i = 0;
 419   while (current_ < next_line) {
 420     if (filename && i < filename_size - 1)
 421       filename[i++] = *current_;
 422     current_++;
 423   }
 424   if (filename && i < filename_size)
 425     filename[i] = 0;
 426   current_ = next_line + 1;
 427   return true;
 428 }
 429
 430 // Gets the object name and the offset by walking MemoryMappingLayout.
 431 bool MemoryMappingLayout::GetObjectNameAndOffset(uptr addr, uptr *offset,
 432                                                  char filename[],
 433                                                  uptr filename_size) {
 434   return IterateForObjectNameAndOffset(addr, offset, filename, filename_size);
 435 }
 436
 437 bool SanitizerSetThreadName(const char *name) {
 438 #ifdef PR_SET_NAME
 439   return 0 == prctl(PR_SET_NAME, (unsigned long)name, 0, 0, 0);  // NOLINT
 440 #else
 441   return false;
 442 #endif
 443 }
 444
 445 bool SanitizerGetThreadName(char *name, int max_len) {
 446 #ifdef PR_GET_NAME
 447   char buff[17];
 448   if (prctl(PR_GET_NAME, (unsigned long)buff, 0, 0, 0))  // NOLINT
 449     return false;
 450   internal_strncpy(name, buff, max_len);
 451   name[max_len] = 0;
 452   return true;
 453 #else
 454   return false;
 455 #endif
 456 }
 457
 458 #ifndef SANITIZER_GO
 459 //------------------------- SlowUnwindStack -----------------------------------
 460 #ifdef __arm__
 461 #define UNWIND_STOP _URC_END_OF_STACK
 462 #define UNWIND_CONTINUE _URC_NO_REASON
 463 #else
 464 #define UNWIND_STOP _URC_NORMAL_STOP
 465 #define UNWIND_CONTINUE _URC_NO_REASON
 466 #endif
 467
 468 uptr Unwind_GetIP(struct _Unwind_Context *ctx) {
 469 #ifdef __arm__
 470   uptr val;
 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;
 476 #else
 477   return _Unwind_GetIP(ctx);
 478 #endif
 479 }
 480
 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;
 488 }
 489
 490 static bool MatchPc(uptr cur_pc, uptr trace_pc) {
 491   return cur_pc - trace_pc <= 64 || trace_pc - cur_pc <= 64;
 492 }
 493
 494 void StackTrace::SlowUnwindStack(uptr pc, uptr max_depth) {
 495   this->size = 0;
 496   this->max_size = max_depth;
 497   if (max_depth > 1) {
 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.
 501     int to_pop = 1;
 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);
 508   }
 509   this->trace[0] = pc;
 510 }
 511
 512 #endif  // #ifndef SANITIZER_GO
 513
 514 enum MutexState {
 515   MtxUnlocked = 0,
 516   MtxLocked = 1,
 517   MtxSleeping = 2
 518 };
 519
 520 BlockingMutex::BlockingMutex(LinkerInitialized) {
 521   CHECK_EQ(owner_, 0);
 522 }
 523
 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)
 527     return;
 528   while (atomic_exchange(m, MtxSleeping, memory_order_acquire) != MtxUnlocked)
 529     syscall(__NR_futex, m, FUTEX_WAIT, MtxSleeping, 0, 0, 0);
 530 }
 531
 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);
 538 }
 539
 540 }  // namespace __sanitizer
 541
 542 #endif  // __linux__