1 //===-- sanitizer_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 shared between AddressSanitizer and ThreadSanitizer
10 // run-time libraries and implements POSIX-specific functions from
11 // sanitizer_posix.h.
12 //===----------------------------------------------------------------------===//
13 
14 #include "sanitizer_platform.h"
15 
16 #if SANITIZER_POSIX
17 
18 #include "sanitizer_common.h"
19 #include "sanitizer_file.h"
20 #include "sanitizer_flags.h"
21 #include "sanitizer_libc.h"
22 #include "sanitizer_posix.h"
23 #include "sanitizer_procmaps.h"
24 
25 #include <errno.h>
26 #include <fcntl.h>
27 #include <signal.h>
28 #include <sys/mman.h>
29 
30 #if SANITIZER_FREEBSD
31 // The MAP_NORESERVE define has been removed in FreeBSD 11.x, and even before
32 // that, it was never implemented.  So just define it to zero.
33 #undef  MAP_NORESERVE
34 #define MAP_NORESERVE 0
35 #endif
36 
37 namespace __sanitizer {
38 
39 // ------------- sanitizer_common.h
40 uptr GetMmapGranularity() {
41   return GetPageSize();
42 }
43 
44 bool ErrorIsOOM(error_t err) { return err == ENOMEM; }
45 
46 void *MmapOrDie(uptr size, const char *mem_type, bool raw_report) {
47   size = RoundUpTo(size, GetPageSizeCached());
48   uptr res = MmapNamed(nullptr, size, PROT_READ | PROT_WRITE,
49                        MAP_PRIVATE | MAP_ANON, mem_type);
50   int reserrno;
51   if (UNLIKELY(internal_iserror(res, &reserrno)))
52     ReportMmapFailureAndDie(size, mem_type, "allocate", reserrno, raw_report);
53   IncreaseTotalMmap(size);
54   return (void *)res;
55 }
56 
57 void UnmapOrDie(void *addr, uptr size) {
58   if (!addr || !size) return;
59   uptr res = internal_munmap(addr, size);
60   int reserrno;
61   if (UNLIKELY(internal_iserror(res, &reserrno)))
62     ReportMunmapFailureAndDie(addr, size, reserrno);
63   DecreaseTotalMmap(size);
64 }
65 
66 void *MmapOrDieOnFatalError(uptr size, const char *mem_type) {
67   size = RoundUpTo(size, GetPageSizeCached());
68   uptr res = MmapNamed(nullptr, size, PROT_READ | PROT_WRITE,
69                        MAP_PRIVATE | MAP_ANON, mem_type);
70   int reserrno;
71   if (UNLIKELY(internal_iserror(res, &reserrno))) {
72     if (reserrno == ENOMEM)
73       return nullptr;
74     ReportMmapFailureAndDie(size, mem_type, "allocate", reserrno);
75   }
76   IncreaseTotalMmap(size);
77   return (void *)res;
78 }
79 
80 // We want to map a chunk of address space aligned to 'alignment'.
81 // We do it by mapping a bit more and then unmapping redundant pieces.
82 // We probably can do it with fewer syscalls in some OS-dependent way.
83 void *MmapAlignedOrDieOnFatalError(uptr size, uptr alignment,
84                                    const char *mem_type) {
85   CHECK(IsPowerOfTwo(size));
86   CHECK(IsPowerOfTwo(alignment));
87   uptr map_size = size + alignment;
88   // mmap maps entire pages and rounds up map_size needs to be a an integral
89   // number of pages.
90   // We need to be aware of this size for calculating end and for unmapping
91   // fragments before and after the alignment region.
92   map_size = RoundUpTo(map_size, GetPageSizeCached());
93   uptr map_res = (uptr)MmapOrDieOnFatalError(map_size, mem_type);
94   if (UNLIKELY(!map_res))
95     return nullptr;
96   uptr res = map_res;
97   if (!IsAligned(res, alignment)) {
98     res = (map_res + alignment - 1) & ~(alignment - 1);
99     UnmapOrDie((void*)map_res, res - map_res);
100   }
101   uptr map_end = map_res + map_size;
102   uptr end = res + size;
103   end = RoundUpTo(end, GetPageSizeCached());
104   if (end != map_end) {
105     CHECK_LT(end, map_end);
106     UnmapOrDie((void*)end, map_end - end);
107   }
108   return (void*)res;
109 }
110 
111 void *MmapNoReserveOrDie(uptr size, const char *mem_type) {
112   size = RoundUpTo(size, GetPageSizeCached());
113   uptr p = MmapNamed(nullptr, size, PROT_READ | PROT_WRITE,
114                      MAP_PRIVATE | MAP_ANON | MAP_NORESERVE, mem_type);
115   int reserrno;
116   if (UNLIKELY(internal_iserror(p, &reserrno)))
117     ReportMmapFailureAndDie(size, mem_type, "allocate noreserve", reserrno);
118   IncreaseTotalMmap(size);
119   return (void *)p;
120 }
121 
122 static void *MmapFixedImpl(uptr fixed_addr, uptr size, bool tolerate_enomem,
123                            const char *name) {
124   size = RoundUpTo(size, GetPageSizeCached());
125   fixed_addr = RoundDownTo(fixed_addr, GetPageSizeCached());
126   uptr p = MmapNamed((void *)fixed_addr, size, PROT_READ | PROT_WRITE,
127                      MAP_PRIVATE | MAP_ANON | MAP_FIXED, name);
128   int reserrno;
129   if (UNLIKELY(internal_iserror(p, &reserrno))) {
130     if (tolerate_enomem && reserrno == ENOMEM)
131       return nullptr;
132     char mem_type[40];
133     internal_snprintf(mem_type, sizeof(mem_type), "memory at address 0x%zx",
134                       fixed_addr);
135     ReportMmapFailureAndDie(size, mem_type, "allocate", reserrno);
136   }
137   IncreaseTotalMmap(size);
138   return (void *)p;
139 }
140 
141 void *MmapFixedOrDie(uptr fixed_addr, uptr size, const char *name) {
142   return MmapFixedImpl(fixed_addr, size, false /*tolerate_enomem*/, name);
143 }
144 
145 void *MmapFixedOrDieOnFatalError(uptr fixed_addr, uptr size, const char *name) {
146   return MmapFixedImpl(fixed_addr, size, true /*tolerate_enomem*/, name);
147 }
148 
149 bool MprotectNoAccess(uptr addr, uptr size) {
150   return 0 == internal_mprotect((void*)addr, size, PROT_NONE);
151 }
152 
153 bool MprotectReadOnly(uptr addr, uptr size) {
154   return 0 == internal_mprotect((void *)addr, size, PROT_READ);
155 }
156 
157 bool MprotectReadWrite(uptr addr, uptr size) {
158   return 0 == internal_mprotect((void *)addr, size, PROT_READ | PROT_WRITE);
159 }
160 
161 #if !SANITIZER_APPLE
162 void MprotectMallocZones(void *addr, int prot) {}
163 #endif
164 
165 fd_t OpenFile(const char *filename, FileAccessMode mode, error_t *errno_p) {
166   if (ShouldMockFailureToOpen(filename))
167     return kInvalidFd;
168   int flags;
169   switch (mode) {
170     case RdOnly: flags = O_RDONLY; break;
171     case WrOnly: flags = O_WRONLY | O_CREAT | O_TRUNC; break;
172     case RdWr: flags = O_RDWR | O_CREAT; break;
173   }
174   fd_t res = internal_open(filename, flags, 0660);
175   if (internal_iserror(res, errno_p))
176     return kInvalidFd;
177   return ReserveStandardFds(res);
178 }
179 
180 void CloseFile(fd_t fd) {
181   internal_close(fd);
182 }
183 
184 bool ReadFromFile(fd_t fd, void *buff, uptr buff_size, uptr *bytes_read,
185                   error_t *error_p) {
186   uptr res = internal_read(fd, buff, buff_size);
187   if (internal_iserror(res, error_p))
188     return false;
189   if (bytes_read)
190     *bytes_read = res;
191   return true;
192 }
193 
194 bool WriteToFile(fd_t fd, const void *buff, uptr buff_size, uptr *bytes_written,
195                  error_t *error_p) {
196   uptr res = internal_write(fd, buff, buff_size);
197   if (internal_iserror(res, error_p))
198     return false;
199   if (bytes_written)
200     *bytes_written = res;
201   return true;
202 }
203 
204 void *MapFileToMemory(const char *file_name, uptr *buff_size) {
205   fd_t fd = OpenFile(file_name, RdOnly);
206   CHECK(fd != kInvalidFd);
207   uptr fsize = internal_filesize(fd);
208   CHECK_NE(fsize, (uptr)-1);
209   CHECK_GT(fsize, 0);
210   *buff_size = RoundUpTo(fsize, GetPageSizeCached());
211   uptr map = internal_mmap(nullptr, *buff_size, PROT_READ, MAP_PRIVATE, fd, 0);
212   return internal_iserror(map) ? nullptr : (void *)map;
213 }
214 
215 void *MapWritableFileToMemory(void *addr, uptr size, fd_t fd, OFF_T offset) {
216   uptr flags = MAP_SHARED;
217   if (addr) flags |= MAP_FIXED;
218   uptr p = internal_mmap(addr, size, PROT_READ | PROT_WRITE, flags, fd, offset);
219   int mmap_errno = 0;
220   if (internal_iserror(p, &mmap_errno)) {
221     Printf("could not map writable file (%d, %lld, %zu): %zd, errno: %d\n",
222            fd, (long long)offset, size, p, mmap_errno);
223     return nullptr;
224   }
225   return (void *)p;
226 }
227 
228 static inline bool IntervalsAreSeparate(uptr start1, uptr end1,
229                                         uptr start2, uptr end2) {
230   CHECK(start1 <= end1);
231   CHECK(start2 <= end2);
232   return (end1 < start2) || (end2 < start1);
233 }
234 
235 // FIXME: this is thread-unsafe, but should not cause problems most of the time.
236 // When the shadow is mapped only a single thread usually exists (plus maybe
237 // several worker threads on Mac, which aren't expected to map big chunks of
238 // memory).
239 bool MemoryRangeIsAvailable(uptr range_start, uptr range_end) {
240   MemoryMappingLayout proc_maps(/*cache_enabled*/true);
241   if (proc_maps.Error())
242     return true; // and hope for the best
243   MemoryMappedSegment segment;
244   while (proc_maps.Next(&segment)) {
245     if (segment.start == segment.end) continue;  // Empty range.
246     CHECK_NE(0, segment.end);
247     if (!IntervalsAreSeparate(segment.start, segment.end - 1, range_start,
248                               range_end))
249       return false;
250   }
251   return true;
252 }
253 
254 #if !SANITIZER_APPLE
255 void DumpProcessMap() {
256   MemoryMappingLayout proc_maps(/*cache_enabled*/true);
257   const sptr kBufSize = 4095;
258   char *filename = (char*)MmapOrDie(kBufSize, __func__);
259   MemoryMappedSegment segment(filename, kBufSize);
260   Report("Process memory map follows:\n");
261   while (proc_maps.Next(&segment)) {
262     Printf("\t%p-%p\t%s\n", (void *)segment.start, (void *)segment.end,
263            segment.filename);
264   }
265   Report("End of process memory map.\n");
266   UnmapOrDie(filename, kBufSize);
267 }
268 #endif
269 
270 const char *GetPwd() {
271   return GetEnv("PWD");
272 }
273 
274 bool IsPathSeparator(const char c) {
275   return c == '/';
276 }
277 
278 bool IsAbsolutePath(const char *path) {
279   return path != nullptr && IsPathSeparator(path[0]);
280 }
281 
282 void ReportFile::Write(const char *buffer, uptr length) {
283   SpinMutexLock l(mu);
284   ReopenIfNecessary();
285   internal_write(fd, buffer, length);
286 }
287 
288 bool GetCodeRangeForFile(const char *module, uptr *start, uptr *end) {
289   MemoryMappingLayout proc_maps(/*cache_enabled*/false);
290   InternalMmapVector<char> buff(kMaxPathLength);
291   MemoryMappedSegment segment(buff.data(), buff.size());
292   while (proc_maps.Next(&segment)) {
293     if (segment.IsExecutable() &&
294         internal_strcmp(module, segment.filename) == 0) {
295       *start = segment.start;
296       *end = segment.end;
297       return true;
298     }
299   }
300   return false;
301 }
302 
303 uptr SignalContext::GetAddress() const {
304   auto si = static_cast<const siginfo_t *>(siginfo);
305   return (uptr)si->si_addr;
306 }
307 
308 bool SignalContext::IsMemoryAccess() const {
309   auto si = static_cast<const siginfo_t *>(siginfo);
310   return si->si_signo == SIGSEGV || si->si_signo == SIGBUS;
311 }
312 
313 int SignalContext::GetType() const {
314   return static_cast<const siginfo_t *>(siginfo)->si_signo;
315 }
316 
317 const char *SignalContext::Describe() const {
318   switch (GetType()) {
319     case SIGFPE:
320       return "FPE";
321     case SIGILL:
322       return "ILL";
323     case SIGABRT:
324       return "ABRT";
325     case SIGSEGV:
326       return "SEGV";
327     case SIGBUS:
328       return "BUS";
329     case SIGTRAP:
330       return "TRAP";
331   }
332   return "UNKNOWN SIGNAL";
333 }
334 
335 fd_t ReserveStandardFds(fd_t fd) {
336   CHECK_GE(fd, 0);
337   if (fd > 2)
338     return fd;
339   bool used[3];
340   internal_memset(used, 0, sizeof(used));
341   while (fd <= 2) {
342     used[fd] = true;
343     fd = internal_dup(fd);
344   }
345   for (int i = 0; i <= 2; ++i)
346     if (used[i])
347       internal_close(i);
348   return fd;
349 }
350 
351 bool ShouldMockFailureToOpen(const char *path) {
352   return common_flags()->test_only_emulate_no_memorymap &&
353          internal_strncmp(path, "/proc/", 6) == 0;
354 }
355 
356 #if SANITIZER_LINUX && !SANITIZER_ANDROID && !SANITIZER_GO
357 int GetNamedMappingFd(const char *name, uptr size, int *flags) {
358   if (!common_flags()->decorate_proc_maps || !name)
359     return -1;
360   char shmname[200];
361   CHECK(internal_strlen(name) < sizeof(shmname) - 10);
362   internal_snprintf(shmname, sizeof(shmname), "/dev/shm/%zu [%s]",
363                     internal_getpid(), name);
364   int o_cloexec = 0;
365 #if defined(O_CLOEXEC)
366   o_cloexec = O_CLOEXEC;
367 #endif
368   int fd = ReserveStandardFds(
369       internal_open(shmname, O_RDWR | O_CREAT | O_TRUNC | o_cloexec, S_IRWXU));
370   CHECK_GE(fd, 0);
371   int res = internal_ftruncate(fd, size);
372 #if !defined(O_CLOEXEC)
373   res = fcntl(fd, F_SETFD, FD_CLOEXEC);
374   CHECK_EQ(0, res);
375 #endif
376   CHECK_EQ(0, res);
377   res = internal_unlink(shmname);
378   CHECK_EQ(0, res);
379   *flags &= ~(MAP_ANON | MAP_ANONYMOUS);
380   return fd;
381 }
382 #else
383 int GetNamedMappingFd(const char *name, uptr size, int *flags) {
384   return -1;
385 }
386 #endif
387 
388 #if SANITIZER_ANDROID
389 #define PR_SET_VMA 0x53564d41
390 #define PR_SET_VMA_ANON_NAME 0
391 void DecorateMapping(uptr addr, uptr size, const char *name) {
392   if (!common_flags()->decorate_proc_maps || !name)
393     return;
394   internal_prctl(PR_SET_VMA, PR_SET_VMA_ANON_NAME, addr, size, (uptr)name);
395 }
396 #else
397 void DecorateMapping(uptr addr, uptr size, const char *name) {
398 }
399 #endif
400 
401 uptr MmapNamed(void *addr, uptr length, int prot, int flags, const char *name) {
402   int fd = GetNamedMappingFd(name, length, &flags);
403   uptr res = internal_mmap(addr, length, prot, flags, fd, 0);
404   if (!internal_iserror(res))
405     DecorateMapping(res, length, name);
406   return res;
407 }
408 
409 
410 } // namespace __sanitizer
411 
412 #endif // SANITIZER_POSIX
413