sanitizer_linux_libcdep.cc revision 2d1fdb26e458c4ddc04155c1d421bced3ba90cd0 
1//===-- sanitizer_linux_libcdep.cc ----------------------------------------===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10// This file is shared between AddressSanitizer and ThreadSanitizer
11// run-time libraries and implements linux-specific functions from
12// sanitizer_libc.h.
13//===----------------------------------------------------------------------===//
14
15#include "sanitizer_platform.h"
16#if SANITIZER_FREEBSD || SANITIZER_LINUX
17
18#include "sanitizer_common.h"
19#include "sanitizer_flags.h"
20#include "sanitizer_linux.h"
21#include "sanitizer_placement_new.h"
22#include "sanitizer_procmaps.h"
23#include "sanitizer_stacktrace.h"
24#include "sanitizer_atomic.h"
25#include "sanitizer_symbolizer.h"
26
27#include <dlfcn.h>
28#include <pthread.h>
29#include <signal.h>
30#include <sys/resource.h>
31#if SANITIZER_FREEBSD
32#define _GNU_SOURCE  // to declare _Unwind_Backtrace() from <unwind.h>
33#endif
34#include <unwind.h>
35
36#if SANITIZER_FREEBSD
37#include <pthread_np.h>
38#define pthread_getattr_np pthread_attr_get_np
39#endif
40
41#if SANITIZER_LINUX
42#include <sys/prctl.h>
43#endif
44
45#if !SANITIZER_ANDROID
46#include <elf.h>
47#include <link.h>
48#include <unistd.h>
49#endif
50
51namespace __sanitizer {
52
53// This function is defined elsewhere if we intercepted pthread_attr_getstack.
54extern "C" {
55SANITIZER_WEAK_ATTRIBUTE int
56real_pthread_attr_getstack(void *attr, void **addr, size_t *size);
57}  // extern "C"
58
59static int my_pthread_attr_getstack(void *attr, void **addr, size_t *size) {
60  if (real_pthread_attr_getstack)
61    return real_pthread_attr_getstack((pthread_attr_t *)attr, addr, size);
62  return pthread_attr_getstack((pthread_attr_t *)attr, addr, size);
63}
64
65SANITIZER_WEAK_ATTRIBUTE int
66real_sigaction(int signum, const void *act, void *oldact);
67
68int internal_sigaction(int signum, const void *act, void *oldact) {
69  if (real_sigaction)
70    return real_sigaction(signum, act, oldact);
71  return sigaction(signum, (struct sigaction *)act, (struct sigaction *)oldact);
72}
73
74void GetThreadStackTopAndBottom(bool at_initialization, uptr *stack_top,
75                                uptr *stack_bottom) {
76  CHECK(stack_top);
77  CHECK(stack_bottom);
78  if (at_initialization) {
79    // This is the main thread. Libpthread may not be initialized yet.
80    struct rlimit rl;
81    CHECK_EQ(getrlimit(RLIMIT_STACK, &rl), 0);
82
83    // Find the mapping that contains a stack variable.
84    MemoryMappingLayout proc_maps(/*cache_enabled*/true);
85    uptr start, end, offset;
86    uptr prev_end = 0;
87    while (proc_maps.Next(&start, &end, &offset, 0, 0, /* protection */0)) {
88      if ((uptr)&rl < end)
89        break;
90      prev_end = end;
91    }
92    CHECK((uptr)&rl >= start && (uptr)&rl < end);
93
94    // Get stacksize from rlimit, but clip it so that it does not overlap
95    // with other mappings.
96    uptr stacksize = rl.rlim_cur;
97    if (stacksize > end - prev_end)
98      stacksize = end - prev_end;
99    // When running with unlimited stack size, we still want to set some limit.
100    // The unlimited stack size is caused by 'ulimit -s unlimited'.
101    // Also, for some reason, GNU make spawns subprocesses with unlimited stack.
102    if (stacksize > kMaxThreadStackSize)
103      stacksize = kMaxThreadStackSize;
104    *stack_top = end;
105    *stack_bottom = end - stacksize;
106    return;
107  }
108  pthread_attr_t attr;
109  pthread_attr_init(&attr);
110  CHECK_EQ(pthread_getattr_np(pthread_self(), &attr), 0);
111  uptr stacksize = 0;
112  void *stackaddr = 0;
113  my_pthread_attr_getstack(&attr, &stackaddr, (size_t*)&stacksize);
114  pthread_attr_destroy(&attr);
115
116  CHECK_LE(stacksize, kMaxThreadStackSize);  // Sanity check.
117  *stack_top = (uptr)stackaddr + stacksize;
118  *stack_bottom = (uptr)stackaddr;
119}
120
121bool SetEnv(const char *name, const char *value) {
122  void *f = dlsym(RTLD_NEXT, "setenv");
123  if (f == 0)
124    return false;
125  typedef int(*setenv_ft)(const char *name, const char *value, int overwrite);
126  setenv_ft setenv_f;
127  CHECK_EQ(sizeof(setenv_f), sizeof(f));
128  internal_memcpy(&setenv_f, &f, sizeof(f));
129  return IndirectExternCall(setenv_f)(name, value, 1) == 0;
130}
131
132bool SanitizerSetThreadName(const char *name) {
133#ifdef PR_SET_NAME
134  return 0 == prctl(PR_SET_NAME, (unsigned long)name, 0, 0, 0);  // NOLINT
135#else
136  return false;
137#endif
138}
139
140bool SanitizerGetThreadName(char *name, int max_len) {
141#ifdef PR_GET_NAME
142  char buff[17];
143  if (prctl(PR_GET_NAME, (unsigned long)buff, 0, 0, 0))  // NOLINT
144    return false;
145  internal_strncpy(name, buff, max_len);
146  name[max_len] = 0;
147  return true;
148#else
149  return false;
150#endif
151}
152
153//------------------------- SlowUnwindStack -----------------------------------
154
155typedef struct {
156  uptr absolute_pc;
157  uptr stack_top;
158  uptr stack_size;
159} backtrace_frame_t;
160
161extern "C" {
162typedef void *(*acquire_my_map_info_list_func)();
163typedef void (*release_my_map_info_list_func)(void *map);
164typedef sptr (*unwind_backtrace_signal_arch_func)(
165    void *siginfo, void *sigcontext, void *map_info_list,
166    backtrace_frame_t *backtrace, uptr ignore_depth, uptr max_depth);
167acquire_my_map_info_list_func acquire_my_map_info_list;
168release_my_map_info_list_func release_my_map_info_list;
169unwind_backtrace_signal_arch_func unwind_backtrace_signal_arch;
170} // extern "C"
171
172#if SANITIZER_ANDROID
173void SanitizerInitializeUnwinder() {
174  void *p = dlopen("libcorkscrew.so", RTLD_LAZY);
175  if (!p) {
176    VReport(1,
177            "Failed to open libcorkscrew.so. You may see broken stack traces "
178            "in SEGV reports.");
179    return;
180  }
181  acquire_my_map_info_list =
182      (acquire_my_map_info_list_func)(uptr)dlsym(p, "acquire_my_map_info_list");
183  release_my_map_info_list =
184      (release_my_map_info_list_func)(uptr)dlsym(p, "release_my_map_info_list");
185  unwind_backtrace_signal_arch = (unwind_backtrace_signal_arch_func)(uptr)dlsym(
186      p, "unwind_backtrace_signal_arch");
187  if (!acquire_my_map_info_list || !release_my_map_info_list ||
188      !unwind_backtrace_signal_arch) {
189    VReport(1,
190            "Failed to find one of the required symbols in libcorkscrew.so. "
191            "You may see broken stack traces in SEGV reports.");
192    acquire_my_map_info_list = NULL;
193    unwind_backtrace_signal_arch = NULL;
194    release_my_map_info_list = NULL;
195  }
196}
197#endif
198
199#ifdef __arm__
200#define UNWIND_STOP _URC_END_OF_STACK
201#define UNWIND_CONTINUE _URC_NO_REASON
202#else
203#define UNWIND_STOP _URC_NORMAL_STOP
204#define UNWIND_CONTINUE _URC_NO_REASON
205#endif
206
207uptr Unwind_GetIP(struct _Unwind_Context *ctx) {
208#ifdef __arm__
209  uptr val;
210  _Unwind_VRS_Result res = _Unwind_VRS_Get(ctx, _UVRSC_CORE,
211      15 /* r15 = PC */, _UVRSD_UINT32, &val);
212  CHECK(res == _UVRSR_OK && "_Unwind_VRS_Get failed");
213  // Clear the Thumb bit.
214  return val & ~(uptr)1;
215#else
216  return _Unwind_GetIP(ctx);
217#endif
218}
219
220struct UnwindTraceArg {
221  StackTrace *stack;
222  uptr max_depth;
223};
224
225_Unwind_Reason_Code Unwind_Trace(struct _Unwind_Context *ctx, void *param) {
226  UnwindTraceArg *arg = (UnwindTraceArg*)param;
227  CHECK_LT(arg->stack->size, arg->max_depth);
228  uptr pc = Unwind_GetIP(ctx);
229  arg->stack->trace[arg->stack->size++] = pc;
230  if (arg->stack->size == arg->max_depth) return UNWIND_STOP;
231  return UNWIND_CONTINUE;
232}
233
234void StackTrace::SlowUnwindStack(uptr pc, uptr max_depth) {
235  CHECK_GE(max_depth, 2);
236  size = 0;
237  UnwindTraceArg arg = {this, Min(max_depth + 1, kStackTraceMax)};
238  _Unwind_Backtrace(Unwind_Trace, &arg);
239  // We need to pop a few frames so that pc is on top.
240  uptr to_pop = LocatePcInTrace(pc);
241  // trace[0] belongs to the current function so we always pop it.
242  if (to_pop == 0)
243    to_pop = 1;
244  PopStackFrames(to_pop);
245  trace[0] = pc;
246}
247
248void StackTrace::SlowUnwindStackWithContext(uptr pc, void *context,
249                                            uptr max_depth) {
250  CHECK_GE(max_depth, 2);
251  if (!unwind_backtrace_signal_arch) {
252    SlowUnwindStack(pc, max_depth);
253    return;
254  }
255
256  void *map = acquire_my_map_info_list();
257  CHECK(map);
258  InternalScopedBuffer<backtrace_frame_t> frames(kStackTraceMax);
259  // siginfo argument appears to be unused.
260  sptr res = unwind_backtrace_signal_arch(/* siginfo */ NULL, context, map,
261                                          frames.data(),
262                                          /* ignore_depth */ 0, max_depth);
263  release_my_map_info_list(map);
264  if (res < 0) return;
265  CHECK_LE((uptr)res, kStackTraceMax);
266
267  size = 0;
268  // +2 compensate for libcorkscrew unwinder returning addresses of call
269  // instructions instead of raw return addresses.
270  for (sptr i = 0; i < res; ++i)
271    trace[size++] = frames[i].absolute_pc + 2;
272}
273
274#if !SANITIZER_FREEBSD
275static uptr g_tls_size;
276#endif
277
278#ifdef __i386__
279# define DL_INTERNAL_FUNCTION __attribute__((regparm(3), stdcall))
280#else
281# define DL_INTERNAL_FUNCTION
282#endif
283
284void InitTlsSize() {
285#if !SANITIZER_FREEBSD && !SANITIZER_ANDROID
286  typedef void (*get_tls_func)(size_t*, size_t*) DL_INTERNAL_FUNCTION;
287  get_tls_func get_tls;
288  void *get_tls_static_info_ptr = dlsym(RTLD_NEXT, "_dl_get_tls_static_info");
289  CHECK_EQ(sizeof(get_tls), sizeof(get_tls_static_info_ptr));
290  internal_memcpy(&get_tls, &get_tls_static_info_ptr,
291                  sizeof(get_tls_static_info_ptr));
292  CHECK_NE(get_tls, 0);
293  size_t tls_size = 0;
294  size_t tls_align = 0;
295  IndirectExternCall(get_tls)(&tls_size, &tls_align);
296  g_tls_size = tls_size;
297#endif  // !SANITIZER_FREEBSD && !SANITIZER_ANDROID
298}
299
300#if (defined(__x86_64__) || defined(__i386__)) && SANITIZER_LINUX
301// sizeof(struct thread) from glibc.
302static atomic_uintptr_t kThreadDescriptorSize;
303
304uptr ThreadDescriptorSize() {
305  char buf[64];
306  uptr val = atomic_load(&kThreadDescriptorSize, memory_order_relaxed);
307  if (val)
308    return val;
309#ifdef _CS_GNU_LIBC_VERSION
310  uptr len = confstr(_CS_GNU_LIBC_VERSION, buf, sizeof(buf));
311  if (len < sizeof(buf) && internal_strncmp(buf, "glibc 2.", 8) == 0) {
312    char *end;
313    int minor = internal_simple_strtoll(buf + 8, &end, 10);
314    if (end != buf + 8 && (*end == '\0' || *end == '.')) {
315      /* sizeof(struct thread) values from various glibc versions.  */
316      if (SANITIZER_X32)
317        val = 1728;  // Assume only one particular version for x32.
318      else if (minor <= 3)
319        val = FIRST_32_SECOND_64(1104, 1696);
320      else if (minor == 4)
321        val = FIRST_32_SECOND_64(1120, 1728);
322      else if (minor == 5)
323        val = FIRST_32_SECOND_64(1136, 1728);
324      else if (minor <= 9)
325        val = FIRST_32_SECOND_64(1136, 1712);
326      else if (minor == 10)
327        val = FIRST_32_SECOND_64(1168, 1776);
328      else if (minor <= 12)
329        val = FIRST_32_SECOND_64(1168, 2288);
330      else
331        val = FIRST_32_SECOND_64(1216, 2304);
332    }
333    if (val)
334      atomic_store(&kThreadDescriptorSize, val, memory_order_relaxed);
335    return val;
336  }
337#endif
338  return 0;
339}
340
341// The offset at which pointer to self is located in the thread descriptor.
342const uptr kThreadSelfOffset = FIRST_32_SECOND_64(8, 16);
343
344uptr ThreadSelfOffset() {
345  return kThreadSelfOffset;
346}
347
348uptr ThreadSelf() {
349  uptr descr_addr;
350# if defined(__i386__)
351  asm("mov %%gs:%c1,%0" : "=r"(descr_addr) : "i"(kThreadSelfOffset));
352# elif defined(__x86_64__)
353  asm("mov %%fs:%c1,%0" : "=r"(descr_addr) : "i"(kThreadSelfOffset));
354# else
355#  error "unsupported CPU arch"
356# endif
357  return descr_addr;
358}
359#endif  // (defined(__x86_64__) || defined(__i386__)) && SANITIZER_LINUX
360
361#if SANITIZER_FREEBSD
362static void **ThreadSelfSegbase() {
363  void **segbase = 0;
364# if defined(__i386__)
365  // sysarch(I386_GET_GSBASE, segbase);
366  __asm __volatile("mov %%gs:0, %0" : "=r" (segbase));
367# elif defined(__x86_64__)
368  // sysarch(AMD64_GET_FSBASE, segbase);
369  __asm __volatile("movq %%fs:0, %0" : "=r" (segbase));
370# else
371#  error "unsupported CPU arch for FreeBSD platform"
372# endif
373  return segbase;
374}
375
376uptr ThreadSelf() {
377  return (uptr)ThreadSelfSegbase()[2];
378}
379#endif  // SANITIZER_FREEBSD
380
381static void GetTls(uptr *addr, uptr *size) {
382#if SANITIZER_LINUX
383# if defined(__x86_64__) || defined(__i386__)
384  *addr = ThreadSelf();
385  *size = GetTlsSize();
386  *addr -= *size;
387  *addr += ThreadDescriptorSize();
388# else
389  *addr = 0;
390  *size = 0;
391# endif
392#elif SANITIZER_FREEBSD
393  void** segbase = ThreadSelfSegbase();
394  *addr = 0;
395  *size = 0;
396  if (segbase != 0) {
397    // tcbalign = 16
398    // tls_size = round(tls_static_space, tcbalign);
399    // dtv = segbase[1];
400    // dtv[2] = segbase - tls_static_space;
401    void **dtv = (void**) segbase[1];
402    *addr = (uptr) dtv[2];
403    *size = (*addr == 0) ? 0 : ((uptr) segbase[0] - (uptr) dtv[2]);
404  }
405#else
406# error "Unknown OS"
407#endif
408}
409
410uptr GetTlsSize() {
411#if SANITIZER_FREEBSD
412  uptr addr, size;
413  GetTls(&addr, &size);
414  return size;
415#else
416  return g_tls_size;
417#endif
418}
419
420void GetThreadStackAndTls(bool main, uptr *stk_addr, uptr *stk_size,
421                          uptr *tls_addr, uptr *tls_size) {
422  GetTls(tls_addr, tls_size);
423
424  uptr stack_top, stack_bottom;
425  GetThreadStackTopAndBottom(main, &stack_top, &stack_bottom);
426  *stk_addr = stack_bottom;
427  *stk_size = stack_top - stack_bottom;
428
429  if (!main) {
430    // If stack and tls intersect, make them non-intersecting.
431    if (*tls_addr > *stk_addr && *tls_addr < *stk_addr + *stk_size) {
432      CHECK_GT(*tls_addr + *tls_size, *stk_addr);
433      CHECK_LE(*tls_addr + *tls_size, *stk_addr + *stk_size);
434      *stk_size -= *tls_size;
435      *tls_addr = *stk_addr + *stk_size;
436    }
437  }
438}
439
440void AdjustStackSize(void *attr_) {
441  pthread_attr_t *attr = (pthread_attr_t *)attr_;
442  uptr stackaddr = 0;
443  size_t stacksize = 0;
444  my_pthread_attr_getstack(attr, (void**)&stackaddr, &stacksize);
445  // GLibC will return (0 - stacksize) as the stack address in the case when
446  // stacksize is set, but stackaddr is not.
447  bool stack_set = (stackaddr != 0) && (stackaddr + stacksize != 0);
448  // We place a lot of tool data into TLS, account for that.
449  const uptr minstacksize = GetTlsSize() + 128*1024;
450  if (stacksize < minstacksize) {
451    if (!stack_set) {
452      if (stacksize != 0) {
453        VPrintf(1, "Sanitizer: increasing stacksize %zu->%zu\n", stacksize,
454                minstacksize);
455        pthread_attr_setstacksize(attr, minstacksize);
456      }
457    } else {
458      Printf("Sanitizer: pre-allocated stack size is insufficient: "
459             "%zu < %zu\n", stacksize, minstacksize);
460      Printf("Sanitizer: pthread_create is likely to fail.\n");
461    }
462  }
463}
464
465#if SANITIZER_ANDROID
466uptr GetListOfModules(LoadedModule *modules, uptr max_modules,
467                      string_predicate_t filter) {
468  MemoryMappingLayout memory_mapping(false);
469  return memory_mapping.DumpListOfModules(modules, max_modules, filter);
470}
471#else  // SANITIZER_ANDROID
472# if !SANITIZER_FREEBSD
473typedef ElfW(Phdr) Elf_Phdr;
474# endif
475
476struct DlIteratePhdrData {
477  LoadedModule *modules;
478  uptr current_n;
479  bool first;
480  uptr max_n;
481  string_predicate_t filter;
482};
483
484static int dl_iterate_phdr_cb(dl_phdr_info *info, size_t size, void *arg) {
485  DlIteratePhdrData *data = (DlIteratePhdrData*)arg;
486  if (data->current_n == data->max_n)
487    return 0;
488  InternalScopedBuffer<char> module_name(kMaxPathLength);
489  module_name.data()[0] = '\0';
490  if (data->first) {
491    data->first = false;
492    // First module is the binary itself.
493    ReadBinaryName(module_name.data(), module_name.size());
494  } else if (info->dlpi_name) {
495    internal_strncpy(module_name.data(), info->dlpi_name, module_name.size());
496  }
497  if (module_name.data()[0] == '\0')
498    return 0;
499  if (data->filter && !data->filter(module_name.data()))
500    return 0;
501  void *mem = &data->modules[data->current_n];
502  LoadedModule *cur_module = new(mem) LoadedModule(module_name.data(),
503                                                   info->dlpi_addr);
504  data->current_n++;
505  for (int i = 0; i < info->dlpi_phnum; i++) {
506    const Elf_Phdr *phdr = &info->dlpi_phdr[i];
507    if (phdr->p_type == PT_LOAD) {
508      uptr cur_beg = info->dlpi_addr + phdr->p_vaddr;
509      uptr cur_end = cur_beg + phdr->p_memsz;
510      cur_module->addAddressRange(cur_beg, cur_end);
511    }
512  }
513  return 0;
514}
515
516uptr GetListOfModules(LoadedModule *modules, uptr max_modules,
517                      string_predicate_t filter) {
518  CHECK(modules);
519  DlIteratePhdrData data = {modules, 0, true, max_modules, filter};
520  dl_iterate_phdr(dl_iterate_phdr_cb, &data);
521  return data.current_n;
522}
523#endif  // SANITIZER_ANDROID
524
525uptr indirect_call_wrapper;
526
527void SetIndirectCallWrapper(uptr wrapper) {
528  CHECK(!indirect_call_wrapper);
529  CHECK(wrapper);
530  indirect_call_wrapper = wrapper;
531}
532
533void PrepareForSandboxing(__sanitizer_sandbox_arguments *args) {
534  // Some kinds of sandboxes may forbid filesystem access, so we won't be able
535  // to read the file mappings from /proc/self/maps. Luckily, neither the
536  // process will be able to load additional libraries, so it's fine to use the
537  // cached mappings.
538  MemoryMappingLayout::CacheMemoryMappings();
539  // Same for /proc/self/exe in the symbolizer.
540#if !SANITIZER_GO
541  if (Symbolizer *sym = Symbolizer::GetOrNull())
542    sym->PrepareForSandboxing();
543  CovPrepareForSandboxing(args);
544#endif
545}
546
547}  // namespace __sanitizer
548
549#endif  // SANITIZER_FREEBSD || SANITIZER_LINUX
550