1 //===-- sanitizer_posix_libcdep.cpp ---------------------------------------===//
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
7 //===----------------------------------------------------------------------===//
9 // This file is shared between AddressSanitizer and ThreadSanitizer
10 // run-time libraries and implements libc-dependent POSIX-specific functions
11 // from sanitizer_libc.h.
12 //===----------------------------------------------------------------------===//
14 #include "sanitizer_platform.h"
18 #include "sanitizer_common.h"
19 #include "sanitizer_flags.h"
20 #include "sanitizer_platform_limits_netbsd.h"
21 #include "sanitizer_platform_limits_posix.h"
22 #include "sanitizer_platform_limits_solaris.h"
23 #include "sanitizer_posix.h"
24 #include "sanitizer_procmaps.h"
32 #include <sys/resource.h>
35 #include <sys/types.h>
40 // The MAP_NORESERVE define has been removed in FreeBSD 11.x, and even before
41 // that, it was never implemented. So just define it to zero.
43 #define MAP_NORESERVE 0
46 typedef void (*sa_sigaction_t
)(int, siginfo_t
*, void *);
48 namespace __sanitizer
{
54 uptr
GetThreadSelf() {
55 return (uptr
)pthread_self();
58 void ReleaseMemoryPagesToOS(uptr beg
, uptr end
) {
59 uptr page_size
= GetPageSizeCached();
60 uptr beg_aligned
= RoundUpTo(beg
, page_size
);
61 uptr end_aligned
= RoundDownTo(end
, page_size
);
62 if (beg_aligned
< end_aligned
)
63 internal_madvise(beg_aligned
, end_aligned
- beg_aligned
,
64 SANITIZER_MADVISE_DONTNEED
);
67 void SetShadowRegionHugePageMode(uptr addr
, uptr size
) {
68 #ifdef MADV_NOHUGEPAGE // May not be defined on old systems.
69 if (common_flags()->no_huge_pages_for_shadow
)
70 internal_madvise(addr
, size
, MADV_NOHUGEPAGE
);
72 internal_madvise(addr
, size
, MADV_HUGEPAGE
);
73 #endif // MADV_NOHUGEPAGE
76 bool DontDumpShadowMemory(uptr addr
, uptr length
) {
77 #if defined(MADV_DONTDUMP)
78 return internal_madvise(addr
, length
, MADV_DONTDUMP
) == 0;
79 #elif defined(MADV_NOCORE)
80 return internal_madvise(addr
, length
, MADV_NOCORE
) == 0;
83 #endif // MADV_DONTDUMP
86 static rlim_t
getlim(int res
) {
88 CHECK_EQ(0, getrlimit(res
, &rlim
));
92 static void setlim(int res
, rlim_t lim
) {
94 if (getrlimit(res
, &rlim
)) {
95 Report("ERROR: %s getrlimit() failed %d\n", SanitizerToolName
, errno
);
99 if (setrlimit(res
, &rlim
)) {
100 Report("ERROR: %s setrlimit() failed %d\n", SanitizerToolName
, errno
);
105 void DisableCoreDumperIfNecessary() {
106 if (common_flags()->disable_coredump
) {
108 CHECK_EQ(0, getrlimit(RLIMIT_CORE
, &rlim
));
109 // On Linux, if the kernel.core_pattern sysctl starts with a '|' (i.e. it
110 // is being piped to a coredump handler such as systemd-coredumpd), the
111 // kernel ignores RLIMIT_CORE (since we aren't creating a file in the file
112 // system) except for the magic value of 1, which disables coredumps when
113 // piping. 1 byte is too small for any kind of valid core dump, so it
114 // also disables coredumps if kernel.core_pattern creates files directly.
115 // While most piped coredump handlers do respect the crashing processes'
116 // RLIMIT_CORE, this is notable not the case for Debian's systemd-coredump
117 // due to a local patch that changes sysctl.d/50-coredump.conf to ignore
118 // the specified limit and instead use RLIM_INFINITY.
120 // The alternative to using RLIMIT_CORE=1 would be to use prctl() with the
121 // PR_SET_DUMPABLE flag, however that also prevents ptrace(), so makes it
122 // impossible to attach a debugger.
124 // Note: we use rlim_max in the Min() call here since that is the upper
125 // limit for what can be set without getting an EINVAL error.
126 rlim
.rlim_cur
= Min
<rlim_t
>(SANITIZER_LINUX
? 1 : 0, rlim
.rlim_max
);
127 CHECK_EQ(0, setrlimit(RLIMIT_CORE
, &rlim
));
131 bool StackSizeIsUnlimited() {
132 rlim_t stack_size
= getlim(RLIMIT_STACK
);
133 return (stack_size
== RLIM_INFINITY
);
136 void SetStackSizeLimitInBytes(uptr limit
) {
137 setlim(RLIMIT_STACK
, (rlim_t
)limit
);
138 CHECK(!StackSizeIsUnlimited());
141 bool AddressSpaceIsUnlimited() {
142 rlim_t as_size
= getlim(RLIMIT_AS
);
143 return (as_size
== RLIM_INFINITY
);
146 void SetAddressSpaceUnlimited() {
147 setlim(RLIMIT_AS
, RLIM_INFINITY
);
148 CHECK(AddressSpaceIsUnlimited());
153 // If we are handling SIGABRT, unhandle it first.
154 // TODO(vitalybuka): Check if handler belongs to sanitizer.
155 if (GetHandleSignalMode(SIGABRT
) != kHandleSignalNo
) {
156 struct sigaction sigact
;
157 internal_memset(&sigact
, 0, sizeof(sigact
));
158 sigact
.sa_handler
= SIG_DFL
;
159 internal_sigaction(SIGABRT
, &sigact
, nullptr);
166 int Atexit(void (*function
)(void)) {
168 return atexit(function
);
174 bool CreateDir(const char *pathname
) { return mkdir(pathname
, 0755) == 0; }
176 bool SupportsColoredOutput(fd_t fd
) {
177 return isatty(fd
) != 0;
181 // TODO(glider): different tools may require different altstack size.
182 static uptr
GetAltStackSize() {
183 // Note: since GLIBC_2.31, SIGSTKSZ may be a function call, so this may be
184 // more costly that you think. However GetAltStackSize is only call 2-3 times
185 // per thread so don't cache the evaluation.
189 void SetAlternateSignalStack() {
190 stack_t altstack
, oldstack
;
191 CHECK_EQ(0, sigaltstack(nullptr, &oldstack
));
192 // If the alternate stack is already in place, do nothing.
193 // Android always sets an alternate stack, but it's too small for us.
194 if (!SANITIZER_ANDROID
&& !(oldstack
.ss_flags
& SS_DISABLE
)) return;
195 // TODO(glider): the mapped stack should have the MAP_STACK flag in the
196 // future. It is not required by man 2 sigaltstack now (they're using
198 altstack
.ss_size
= GetAltStackSize();
199 altstack
.ss_sp
= (char *)MmapOrDie(altstack
.ss_size
, __func__
);
200 altstack
.ss_flags
= 0;
201 CHECK_EQ(0, sigaltstack(&altstack
, nullptr));
204 void UnsetAlternateSignalStack() {
205 stack_t altstack
, oldstack
;
206 altstack
.ss_sp
= nullptr;
207 altstack
.ss_flags
= SS_DISABLE
;
208 altstack
.ss_size
= GetAltStackSize(); // Some sane value required on Darwin.
209 CHECK_EQ(0, sigaltstack(&altstack
, &oldstack
));
210 UnmapOrDie(oldstack
.ss_sp
, oldstack
.ss_size
);
213 static void MaybeInstallSigaction(int signum
,
214 SignalHandlerType handler
) {
215 if (GetHandleSignalMode(signum
) == kHandleSignalNo
) return;
217 struct sigaction sigact
;
218 internal_memset(&sigact
, 0, sizeof(sigact
));
219 sigact
.sa_sigaction
= (sa_sigaction_t
)handler
;
220 // Do not block the signal from being received in that signal's handler.
221 // Clients are responsible for handling this correctly.
222 sigact
.sa_flags
= SA_SIGINFO
| SA_NODEFER
;
223 if (common_flags()->use_sigaltstack
) sigact
.sa_flags
|= SA_ONSTACK
;
224 CHECK_EQ(0, internal_sigaction(signum
, &sigact
, nullptr));
225 VReport(1, "Installed the sigaction for signal %d\n", signum
);
228 void InstallDeadlySignalHandlers(SignalHandlerType handler
) {
229 // Set the alternate signal stack for the main thread.
230 // This will cause SetAlternateSignalStack to be called twice, but the stack
231 // will be actually set only once.
232 if (common_flags()->use_sigaltstack
) SetAlternateSignalStack();
233 MaybeInstallSigaction(SIGSEGV
, handler
);
234 MaybeInstallSigaction(SIGBUS
, handler
);
235 MaybeInstallSigaction(SIGABRT
, handler
);
236 MaybeInstallSigaction(SIGFPE
, handler
);
237 MaybeInstallSigaction(SIGILL
, handler
);
238 MaybeInstallSigaction(SIGTRAP
, handler
);
241 bool SignalContext::IsStackOverflow() const {
242 // Access at a reasonable offset above SP, or slightly below it (to account
243 // for x86_64 or PowerPC redzone, ARM push of multiple registers, etc) is
244 // probably a stack overflow.
246 // On s390, the fault address in siginfo points to start of the page, not
247 // to the precise word that was accessed. Mask off the low bits of sp to
248 // take it into account.
249 bool IsStackAccess
= addr
>= (sp
& ~0xFFF) && addr
< sp
+ 0xFFFF;
251 // Let's accept up to a page size away from top of stack. Things like stack
252 // probing can trigger accesses with such large offsets.
253 bool IsStackAccess
= addr
+ GetPageSizeCached() > sp
&& addr
< sp
+ 0xFFFF;
257 // Large stack frames can be allocated with e.g.
259 // stdux r1,r1,r0 # store sp to [sp-10000] and update sp by -10000
260 // If the store faults then sp will not have been updated, so test above
261 // will not work, because the fault address will be more than just "slightly"
263 if (!IsStackAccess
&& IsAccessibleMemoryRange(pc
, 4)) {
264 u32 inst
= *(unsigned *)pc
;
265 u32 ra
= (inst
>> 16) & 0x1F;
266 u32 opcd
= inst
>> 26;
267 u32 xo
= (inst
>> 1) & 0x3FF;
268 // Check for store-with-update to sp. The instructions we accept are:
269 // stbu rs,d(ra) stbux rs,ra,rb
270 // sthu rs,d(ra) sthux rs,ra,rb
271 // stwu rs,d(ra) stwux rs,ra,rb
272 // stdu rs,ds(ra) stdux rs,ra,rb
273 // where ra is r1 (the stack pointer).
275 (opcd
== 39 || opcd
== 45 || opcd
== 37 || opcd
== 62 ||
276 (opcd
== 31 && (xo
== 247 || xo
== 439 || xo
== 183 || xo
== 181))))
277 IsStackAccess
= true;
279 #endif // __powerpc__
281 // We also check si_code to filter out SEGV caused by something else other
282 // then hitting the guard page or unmapped memory, like, for example,
283 // unaligned memory access.
284 auto si
= static_cast<const siginfo_t
*>(siginfo
);
285 return IsStackAccess
&&
286 (si
->si_code
== si_SEGV_MAPERR
|| si
->si_code
== si_SEGV_ACCERR
);
289 #endif // SANITIZER_GO
291 static void SetNonBlock(int fd
) {
292 int res
= fcntl(fd
, F_GETFL
, 0);
293 CHECK(!internal_iserror(res
, nullptr));
296 res
= fcntl(fd
, F_SETFL
, res
);
297 CHECK(!internal_iserror(res
, nullptr));
300 bool IsAccessibleMemoryRange(uptr beg
, uptr size
) {
302 // `read` from `fds[0]` into a dummy buffer to free up the pipe buffer for
303 // more `write` is slower than just recreating a pipe.
305 CHECK_EQ(0, pipe(fds
));
307 auto cleanup
= at_scope_exit([&]() {
308 internal_close(fds
[0]);
309 internal_close(fds
[1]);
315 uptr w
= internal_write(fds
[1], reinterpret_cast<char *>(beg
), size
);
316 if (internal_iserror(w
, &write_errno
)) {
317 if (write_errno
== EINTR
)
319 CHECK_EQ(EFAULT
, write_errno
);
329 bool TryMemCpy(void *dest
, const void *src
, uptr n
) {
333 CHECK_EQ(0, pipe(fds
));
335 auto cleanup
= at_scope_exit([&]() {
336 internal_close(fds
[0]);
337 internal_close(fds
[1]);
343 char *d
= static_cast<char *>(dest
);
344 const char *s
= static_cast<const char *>(src
);
348 uptr w
= internal_write(fds
[1], s
, n
);
349 if (internal_iserror(w
, &e
)) {
359 uptr r
= internal_read(fds
[0], d
, w
);
360 if (internal_iserror(r
, &e
)) {
373 void PlatformPrepareForSandboxing(void *args
) {
374 // Some kinds of sandboxes may forbid filesystem access, so we won't be able
375 // to read the file mappings from /proc/self/maps. Luckily, neither the
376 // process will be able to load additional libraries, so it's fine to use the
378 MemoryMappingLayout::CacheMemoryMappings();
381 static bool MmapFixed(uptr fixed_addr
, uptr size
, int additional_flags
,
383 size
= RoundUpTo(size
, GetPageSizeCached());
384 fixed_addr
= RoundDownTo(fixed_addr
, GetPageSizeCached());
386 MmapNamed((void *)fixed_addr
, size
, PROT_READ
| PROT_WRITE
,
387 MAP_PRIVATE
| MAP_FIXED
| additional_flags
| MAP_ANON
, name
);
389 if (internal_iserror(p
, &reserrno
)) {
391 "ERROR: %s failed to "
392 "allocate 0x%zx (%zd) bytes at address %p (errno: %d)\n",
393 SanitizerToolName
, size
, size
, (void *)fixed_addr
, reserrno
);
396 IncreaseTotalMmap(size
);
400 bool MmapFixedNoReserve(uptr fixed_addr
, uptr size
, const char *name
) {
401 return MmapFixed(fixed_addr
, size
, MAP_NORESERVE
, name
);
404 bool MmapFixedSuperNoReserve(uptr fixed_addr
, uptr size
, const char *name
) {
405 #if SANITIZER_FREEBSD
406 if (common_flags()->no_huge_pages_for_shadow
)
407 return MmapFixedNoReserve(fixed_addr
, size
, name
);
408 // MAP_NORESERVE is implicit with FreeBSD
409 return MmapFixed(fixed_addr
, size
, MAP_ALIGNED_SUPER
, name
);
411 bool r
= MmapFixedNoReserve(fixed_addr
, size
, name
);
413 SetShadowRegionHugePageMode(fixed_addr
, size
);
418 uptr
ReservedAddressRange::Init(uptr size
, const char *name
, uptr fixed_addr
) {
419 base_
= fixed_addr
? MmapFixedNoAccess(fixed_addr
, size
, name
)
420 : MmapNoAccess(size
);
423 (void)os_handle_
; // unsupported
424 return reinterpret_cast<uptr
>(base_
);
427 // Uses fixed_addr for now.
428 // Will use offset instead once we've implemented this function for real.
429 uptr
ReservedAddressRange::Map(uptr fixed_addr
, uptr size
, const char *name
) {
430 return reinterpret_cast<uptr
>(
431 MmapFixedOrDieOnFatalError(fixed_addr
, size
, name
));
434 uptr
ReservedAddressRange::MapOrDie(uptr fixed_addr
, uptr size
,
436 return reinterpret_cast<uptr
>(MmapFixedOrDie(fixed_addr
, size
, name
));
439 void ReservedAddressRange::Unmap(uptr addr
, uptr size
) {
440 CHECK_LE(size
, size_
);
441 if (addr
== reinterpret_cast<uptr
>(base_
))
442 // If we unmap the whole range, just null out the base.
443 base_
= (size
== size_
) ? nullptr : reinterpret_cast<void*>(addr
+ size
);
445 CHECK_EQ(addr
+ size
, reinterpret_cast<uptr
>(base_
) + size_
);
447 UnmapOrDie(reinterpret_cast<void*>(addr
), size
);
450 void *MmapFixedNoAccess(uptr fixed_addr
, uptr size
, const char *name
) {
451 return (void *)MmapNamed((void *)fixed_addr
, size
, PROT_NONE
,
452 MAP_PRIVATE
| MAP_FIXED
| MAP_NORESERVE
| MAP_ANON
,
456 void *MmapNoAccess(uptr size
) {
457 unsigned flags
= MAP_PRIVATE
| MAP_ANON
| MAP_NORESERVE
;
458 return (void *)internal_mmap(nullptr, size
, PROT_NONE
, flags
, -1, 0);
461 // This function is defined elsewhere if we intercepted pthread_attr_getstack.
463 SANITIZER_WEAK_ATTRIBUTE
int
464 real_pthread_attr_getstack(void *attr
, void **addr
, size_t *size
);
467 int internal_pthread_attr_getstack(void *attr
, void **addr
, uptr
*size
) {
468 #if !SANITIZER_GO && !SANITIZER_APPLE
469 if (&real_pthread_attr_getstack
)
470 return real_pthread_attr_getstack((pthread_attr_t
*)attr
, addr
,
473 return pthread_attr_getstack((pthread_attr_t
*)attr
, addr
, (size_t *)size
);
477 void AdjustStackSize(void *attr_
) {
478 pthread_attr_t
*attr
= (pthread_attr_t
*)attr_
;
481 internal_pthread_attr_getstack(attr
, (void **)&stackaddr
, &stacksize
);
482 // GLibC will return (0 - stacksize) as the stack address in the case when
483 // stacksize is set, but stackaddr is not.
484 bool stack_set
= (stackaddr
!= 0) && (stackaddr
+ stacksize
!= 0);
485 // We place a lot of tool data into TLS, account for that.
486 const uptr minstacksize
= GetTlsSize() + 128*1024;
487 if (stacksize
< minstacksize
) {
489 if (stacksize
!= 0) {
490 VPrintf(1, "Sanitizer: increasing stacksize %zu->%zu\n", stacksize
,
492 pthread_attr_setstacksize(attr
, minstacksize
);
495 Printf("Sanitizer: pre-allocated stack size is insufficient: "
496 "%zu < %zu\n", stacksize
, minstacksize
);
497 Printf("Sanitizer: pthread_create is likely to fail.\n");
501 #endif // !SANITIZER_GO
503 pid_t
StartSubprocess(const char *program
, const char *const argv
[],
504 const char *const envp
[], fd_t stdin_fd
, fd_t stdout_fd
,
506 auto file_closer
= at_scope_exit([&] {
507 if (stdin_fd
!= kInvalidFd
) {
508 internal_close(stdin_fd
);
510 if (stdout_fd
!= kInvalidFd
) {
511 internal_close(stdout_fd
);
513 if (stderr_fd
!= kInvalidFd
) {
514 internal_close(stderr_fd
);
518 int pid
= internal_fork();
522 if (internal_iserror(pid
, &rverrno
)) {
523 Report("WARNING: failed to fork (errno %d)\n", rverrno
);
530 if (stdin_fd
!= kInvalidFd
) {
531 internal_close(STDIN_FILENO
);
532 internal_dup2(stdin_fd
, STDIN_FILENO
);
533 internal_close(stdin_fd
);
535 if (stdout_fd
!= kInvalidFd
) {
536 internal_close(STDOUT_FILENO
);
537 internal_dup2(stdout_fd
, STDOUT_FILENO
);
538 internal_close(stdout_fd
);
540 if (stderr_fd
!= kInvalidFd
) {
541 internal_close(STDERR_FILENO
);
542 internal_dup2(stderr_fd
, STDERR_FILENO
);
543 internal_close(stderr_fd
);
546 # if SANITIZER_FREEBSD
547 internal_close_range(3, ~static_cast<fd_t
>(0), 0);
549 for (int fd
= sysconf(_SC_OPEN_MAX
); fd
> 2; fd
--) internal_close(fd
);
552 internal_execve(program
, const_cast<char **>(&argv
[0]),
553 const_cast<char *const *>(envp
));
560 bool IsProcessRunning(pid_t pid
) {
562 uptr waitpid_status
= internal_waitpid(pid
, &process_status
, WNOHANG
);
564 if (internal_iserror(waitpid_status
, &local_errno
)) {
565 VReport(1, "Waiting on the process failed (errno %d).\n", local_errno
);
568 return waitpid_status
== 0;
571 int WaitForProcess(pid_t pid
) {
573 uptr waitpid_status
= internal_waitpid(pid
, &process_status
, 0);
575 if (internal_iserror(waitpid_status
, &local_errno
)) {
576 VReport(1, "Waiting on the process failed (errno %d).\n", local_errno
);
579 return process_status
;
582 bool IsStateDetached(int state
) {
583 return state
== PTHREAD_CREATE_DETACHED
;
586 } // namespace __sanitizer
588 #endif // SANITIZER_POSIX