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