1 | /* Copyright (C) 2002-2020 Free Software Foundation, Inc. |
2 | This file is part of the GNU C Library. |
3 | Contributed by Ulrich Drepper <drepper@redhat.com>, 2002. |
4 | |
5 | The GNU C Library is free software; you can redistribute it and/or |
6 | modify it under the terms of the GNU Lesser General Public |
7 | License as published by the Free Software Foundation; either |
8 | version 2.1 of the License, or (at your option) any later version. |
9 | |
10 | The GNU C Library is distributed in the hope that it will be useful, |
11 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
12 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
13 | Lesser General Public License for more details. |
14 | |
15 | You should have received a copy of the GNU Lesser General Public |
16 | License along with the GNU C Library; if not, see |
17 | <https://www.gnu.org/licenses/>. */ |
18 | |
19 | #include <assert.h> |
20 | #include <errno.h> |
21 | #include <limits.h> |
22 | #include <signal.h> |
23 | #include <stdlib.h> |
24 | #include <unistd.h> |
25 | #include <sys/param.h> |
26 | #include <sys/resource.h> |
27 | #include <pthreadP.h> |
28 | #include <atomic.h> |
29 | #include <ldsodefs.h> |
30 | #include <tls.h> |
31 | #include <list.h> |
32 | #include <fork.h> |
33 | #include <version.h> |
34 | #include <shlib-compat.h> |
35 | #include <smp.h> |
36 | #include <lowlevellock.h> |
37 | #include <futex-internal.h> |
38 | #include <kernel-features.h> |
39 | #include <libc-pointer-arith.h> |
40 | #include <pthread-pids.h> |
41 | #include <pthread_mutex_conf.h> |
42 | |
43 | #ifndef TLS_MULTIPLE_THREADS_IN_TCB |
44 | /* Pointer to the corresponding variable in libc. */ |
45 | int *__libc_multiple_threads_ptr attribute_hidden; |
46 | #endif |
47 | |
48 | /* Size and alignment of static TLS block. */ |
49 | size_t __static_tls_size; |
50 | size_t __static_tls_align_m1; |
51 | |
52 | #ifndef __ASSUME_SET_ROBUST_LIST |
53 | /* Negative if we do not have the system call and we can use it. */ |
54 | int __set_robust_list_avail; |
55 | # define set_robust_list_not_avail() \ |
56 | __set_robust_list_avail = -1 |
57 | #else |
58 | # define set_robust_list_not_avail() do { } while (0) |
59 | #endif |
60 | |
61 | /* Version of the library, used in libthread_db to detect mismatches. */ |
62 | static const char nptl_version[] __attribute_used__ = VERSION; |
63 | |
64 | |
65 | #ifdef SHARED |
66 | static |
67 | #else |
68 | extern |
69 | #endif |
70 | void __nptl_set_robust (struct pthread *); |
71 | |
72 | #ifdef SHARED |
73 | static const struct pthread_functions pthread_functions = |
74 | { |
75 | .ptr_pthread_attr_getschedpolicy = __pthread_attr_getschedpolicy, |
76 | .ptr_pthread_attr_setschedpolicy = __pthread_attr_setschedpolicy, |
77 | .ptr_pthread_attr_getscope = __pthread_attr_getscope, |
78 | .ptr_pthread_attr_setscope = __pthread_attr_setscope, |
79 | .ptr_pthread_condattr_destroy = __pthread_condattr_destroy, |
80 | .ptr_pthread_condattr_init = __pthread_condattr_init, |
81 | .ptr___pthread_cond_broadcast = __pthread_cond_broadcast, |
82 | .ptr___pthread_cond_destroy = __pthread_cond_destroy, |
83 | .ptr___pthread_cond_init = __pthread_cond_init, |
84 | .ptr___pthread_cond_signal = __pthread_cond_signal, |
85 | .ptr___pthread_cond_wait = __pthread_cond_wait, |
86 | .ptr___pthread_cond_timedwait = __pthread_cond_timedwait, |
87 | # if SHLIB_COMPAT(libpthread, GLIBC_2_0, GLIBC_2_3_2) |
88 | .ptr___pthread_cond_broadcast_2_0 = __pthread_cond_broadcast_2_0, |
89 | .ptr___pthread_cond_destroy_2_0 = __pthread_cond_destroy_2_0, |
90 | .ptr___pthread_cond_init_2_0 = __pthread_cond_init_2_0, |
91 | .ptr___pthread_cond_signal_2_0 = __pthread_cond_signal_2_0, |
92 | .ptr___pthread_cond_wait_2_0 = __pthread_cond_wait_2_0, |
93 | .ptr___pthread_cond_timedwait_2_0 = __pthread_cond_timedwait_2_0, |
94 | # endif |
95 | .ptr___pthread_exit = __pthread_exit, |
96 | .ptr_pthread_getschedparam = __pthread_getschedparam, |
97 | .ptr_pthread_setschedparam = __pthread_setschedparam, |
98 | .ptr_pthread_mutex_destroy = __pthread_mutex_destroy, |
99 | .ptr_pthread_mutex_init = __pthread_mutex_init, |
100 | .ptr_pthread_mutex_lock = __pthread_mutex_lock, |
101 | .ptr_pthread_mutex_unlock = __pthread_mutex_unlock, |
102 | .ptr___pthread_setcancelstate = __pthread_setcancelstate, |
103 | .ptr_pthread_setcanceltype = __pthread_setcanceltype, |
104 | .ptr___pthread_cleanup_upto = __pthread_cleanup_upto, |
105 | .ptr___pthread_once = __pthread_once, |
106 | .ptr___pthread_rwlock_rdlock = __pthread_rwlock_rdlock, |
107 | .ptr___pthread_rwlock_wrlock = __pthread_rwlock_wrlock, |
108 | .ptr___pthread_rwlock_unlock = __pthread_rwlock_unlock, |
109 | .ptr___pthread_key_create = __pthread_key_create, |
110 | .ptr___pthread_getspecific = __pthread_getspecific, |
111 | .ptr___pthread_setspecific = __pthread_setspecific, |
112 | .ptr__pthread_cleanup_push_defer = __pthread_cleanup_push_defer, |
113 | .ptr__pthread_cleanup_pop_restore = __pthread_cleanup_pop_restore, |
114 | .ptr_nthreads = &__nptl_nthreads, |
115 | .ptr___pthread_unwind = &__pthread_unwind, |
116 | .ptr__nptl_deallocate_tsd = __nptl_deallocate_tsd, |
117 | .ptr__nptl_setxid = __nptl_setxid, |
118 | .ptr_set_robust = __nptl_set_robust |
119 | }; |
120 | # define ptr_pthread_functions &pthread_functions |
121 | #else |
122 | # define ptr_pthread_functions NULL |
123 | #endif |
124 | |
125 | |
126 | #ifdef SHARED |
127 | static |
128 | #endif |
129 | void |
130 | __nptl_set_robust (struct pthread *self) |
131 | { |
132 | #ifdef __NR_set_robust_list |
133 | INTERNAL_SYSCALL_DECL (err); |
134 | INTERNAL_SYSCALL (set_robust_list, err, 2, &self->robust_head, |
135 | sizeof (struct robust_list_head)); |
136 | #endif |
137 | } |
138 | |
139 | |
140 | /* For asynchronous cancellation we use a signal. This is the handler. */ |
141 | static void |
142 | sigcancel_handler (int sig, siginfo_t *si, void *ctx) |
143 | { |
144 | /* Safety check. It would be possible to call this function for |
145 | other signals and send a signal from another process. This is not |
146 | correct and might even be a security problem. Try to catch as |
147 | many incorrect invocations as possible. */ |
148 | if (sig != SIGCANCEL |
149 | || si->si_pid != __getpid() |
150 | || si->si_code != SI_TKILL) |
151 | return; |
152 | |
153 | struct pthread *self = THREAD_SELF; |
154 | |
155 | int oldval = THREAD_GETMEM (self, cancelhandling); |
156 | while (1) |
157 | { |
158 | /* We are canceled now. When canceled by another thread this flag |
159 | is already set but if the signal is directly send (internally or |
160 | from another process) is has to be done here. */ |
161 | int newval = oldval | CANCELING_BITMASK | CANCELED_BITMASK; |
162 | |
163 | if (oldval == newval || (oldval & EXITING_BITMASK) != 0) |
164 | /* Already canceled or exiting. */ |
165 | break; |
166 | |
167 | int curval = THREAD_ATOMIC_CMPXCHG_VAL (self, cancelhandling, newval, |
168 | oldval); |
169 | if (curval == oldval) |
170 | { |
171 | /* Set the return value. */ |
172 | THREAD_SETMEM (self, result, PTHREAD_CANCELED); |
173 | |
174 | /* Make sure asynchronous cancellation is still enabled. */ |
175 | if ((newval & CANCELTYPE_BITMASK) != 0) |
176 | /* Run the registered destructors and terminate the thread. */ |
177 | __do_cancel (); |
178 | |
179 | break; |
180 | } |
181 | |
182 | oldval = curval; |
183 | } |
184 | } |
185 | |
186 | |
187 | struct xid_command *__xidcmd attribute_hidden; |
188 | |
189 | /* We use the SIGSETXID signal in the setuid, setgid, etc. implementations to |
190 | tell each thread to call the respective setxid syscall on itself. This is |
191 | the handler. */ |
192 | static void |
193 | sighandler_setxid (int sig, siginfo_t *si, void *ctx) |
194 | { |
195 | int result; |
196 | |
197 | /* Safety check. It would be possible to call this function for |
198 | other signals and send a signal from another process. This is not |
199 | correct and might even be a security problem. Try to catch as |
200 | many incorrect invocations as possible. */ |
201 | if (sig != SIGSETXID |
202 | || si->si_pid != __getpid () |
203 | || si->si_code != SI_TKILL) |
204 | return; |
205 | |
206 | INTERNAL_SYSCALL_DECL (err); |
207 | result = INTERNAL_SYSCALL_NCS (__xidcmd->syscall_no, err, 3, __xidcmd->id[0], |
208 | __xidcmd->id[1], __xidcmd->id[2]); |
209 | int error = 0; |
210 | if (__glibc_unlikely (INTERNAL_SYSCALL_ERROR_P (result, err))) |
211 | error = INTERNAL_SYSCALL_ERRNO (result, err); |
212 | __nptl_setxid_error (__xidcmd, error); |
213 | |
214 | /* Reset the SETXID flag. */ |
215 | struct pthread *self = THREAD_SELF; |
216 | int flags, newval; |
217 | do |
218 | { |
219 | flags = THREAD_GETMEM (self, cancelhandling); |
220 | newval = THREAD_ATOMIC_CMPXCHG_VAL (self, cancelhandling, |
221 | flags & ~SETXID_BITMASK, flags); |
222 | } |
223 | while (flags != newval); |
224 | |
225 | /* And release the futex. */ |
226 | self->setxid_futex = 1; |
227 | futex_wake (&self->setxid_futex, 1, FUTEX_PRIVATE); |
228 | |
229 | if (atomic_decrement_val (&__xidcmd->cntr) == 0) |
230 | futex_wake ((unsigned int *) &__xidcmd->cntr, 1, FUTEX_PRIVATE); |
231 | } |
232 | |
233 | |
234 | /* When using __thread for this, we do it in libc so as not |
235 | to give libpthread its own TLS segment just for this. */ |
236 | extern void **__libc_dl_error_tsd (void) __attribute__ ((const)); |
237 | |
238 | |
239 | /* This can be set by the debugger before initialization is complete. */ |
240 | static bool __nptl_initial_report_events __attribute_used__; |
241 | |
242 | void |
243 | __pthread_initialize_minimal_internal (void) |
244 | { |
245 | /* Minimal initialization of the thread descriptor. */ |
246 | struct pthread *pd = THREAD_SELF; |
247 | __pthread_initialize_pids (pd); |
248 | THREAD_SETMEM (pd, specific[0], &pd->specific_1stblock[0]); |
249 | THREAD_SETMEM (pd, user_stack, true); |
250 | |
251 | /* Initialize the robust mutex data. */ |
252 | { |
253 | #if __PTHREAD_MUTEX_HAVE_PREV |
254 | pd->robust_prev = &pd->robust_head; |
255 | #endif |
256 | pd->robust_head.list = &pd->robust_head; |
257 | #ifdef __NR_set_robust_list |
258 | pd->robust_head.futex_offset = (offsetof (pthread_mutex_t, __data.__lock) |
259 | - offsetof (pthread_mutex_t, |
260 | __data.__list.__next)); |
261 | INTERNAL_SYSCALL_DECL (err); |
262 | int res = INTERNAL_SYSCALL (set_robust_list, err, 2, &pd->robust_head, |
263 | sizeof (struct robust_list_head)); |
264 | if (INTERNAL_SYSCALL_ERROR_P (res, err)) |
265 | #endif |
266 | set_robust_list_not_avail (); |
267 | } |
268 | |
269 | /* Set initial thread's stack block from 0 up to __libc_stack_end. |
270 | It will be bigger than it actually is, but for unwind.c/pt-longjmp.c |
271 | purposes this is good enough. */ |
272 | THREAD_SETMEM (pd, stackblock_size, (size_t) __libc_stack_end); |
273 | |
274 | /* Initialize the list of all running threads with the main thread. */ |
275 | INIT_LIST_HEAD (&__stack_user); |
276 | list_add (&pd->list, &__stack_user); |
277 | |
278 | /* Before initializing __stack_user, the debugger could not find us and |
279 | had to set __nptl_initial_report_events. Propagate its setting. */ |
280 | THREAD_SETMEM (pd, report_events, __nptl_initial_report_events); |
281 | |
282 | struct sigaction sa; |
283 | __sigemptyset (&sa.sa_mask); |
284 | |
285 | /* Install the cancellation signal handler. If for some reason we |
286 | cannot install the handler we do not abort. Maybe we should, but |
287 | it is only asynchronous cancellation which is affected. */ |
288 | sa.sa_sigaction = sigcancel_handler; |
289 | sa.sa_flags = SA_SIGINFO; |
290 | (void) __libc_sigaction (SIGCANCEL, &sa, NULL); |
291 | |
292 | /* Install the handle to change the threads' uid/gid. */ |
293 | sa.sa_sigaction = sighandler_setxid; |
294 | sa.sa_flags = SA_SIGINFO | SA_RESTART; |
295 | (void) __libc_sigaction (SIGSETXID, &sa, NULL); |
296 | |
297 | /* The parent process might have left the signals blocked. Just in |
298 | case, unblock it. We reuse the signal mask in the sigaction |
299 | structure. It is already cleared. */ |
300 | __sigaddset (&sa.sa_mask, SIGCANCEL); |
301 | __sigaddset (&sa.sa_mask, SIGSETXID); |
302 | { |
303 | INTERNAL_SYSCALL_DECL (err); |
304 | (void) INTERNAL_SYSCALL (rt_sigprocmask, err, 4, SIG_UNBLOCK, &sa.sa_mask, |
305 | NULL, _NSIG / 8); |
306 | } |
307 | |
308 | /* Get the size of the static and alignment requirements for the TLS |
309 | block. */ |
310 | size_t static_tls_align; |
311 | _dl_get_tls_static_info (&__static_tls_size, &static_tls_align); |
312 | |
313 | /* Make sure the size takes all the alignments into account. */ |
314 | if (STACK_ALIGN > static_tls_align) |
315 | static_tls_align = STACK_ALIGN; |
316 | __static_tls_align_m1 = static_tls_align - 1; |
317 | |
318 | __static_tls_size = roundup (__static_tls_size, static_tls_align); |
319 | |
320 | /* Determine the default allowed stack size. This is the size used |
321 | in case the user does not specify one. */ |
322 | struct rlimit limit; |
323 | if (__getrlimit (RLIMIT_STACK, &limit) != 0 |
324 | || limit.rlim_cur == RLIM_INFINITY) |
325 | /* The system limit is not usable. Use an architecture-specific |
326 | default. */ |
327 | limit.rlim_cur = ARCH_STACK_DEFAULT_SIZE; |
328 | else if (limit.rlim_cur < PTHREAD_STACK_MIN) |
329 | /* The system limit is unusably small. |
330 | Use the minimal size acceptable. */ |
331 | limit.rlim_cur = PTHREAD_STACK_MIN; |
332 | |
333 | /* Make sure it meets the minimum size that allocate_stack |
334 | (allocatestack.c) will demand, which depends on the page size. */ |
335 | const uintptr_t pagesz = GLRO(dl_pagesize); |
336 | const size_t minstack = pagesz + __static_tls_size + MINIMAL_REST_STACK; |
337 | if (limit.rlim_cur < minstack) |
338 | limit.rlim_cur = minstack; |
339 | |
340 | /* Round the resource limit up to page size. */ |
341 | limit.rlim_cur = ALIGN_UP (limit.rlim_cur, pagesz); |
342 | lll_lock (__default_pthread_attr_lock, LLL_PRIVATE); |
343 | __default_pthread_attr.stacksize = limit.rlim_cur; |
344 | __default_pthread_attr.guardsize = GLRO (dl_pagesize); |
345 | lll_unlock (__default_pthread_attr_lock, LLL_PRIVATE); |
346 | |
347 | #ifdef SHARED |
348 | /* Make __rtld_lock_{,un}lock_recursive use pthread_mutex_{,un}lock, |
349 | keep the lock count from the ld.so implementation. */ |
350 | GL(dl_rtld_lock_recursive) = (void *) __pthread_mutex_lock; |
351 | GL(dl_rtld_unlock_recursive) = (void *) __pthread_mutex_unlock; |
352 | unsigned int rtld_lock_count = GL(dl_load_lock).mutex.__data.__count; |
353 | GL(dl_load_lock).mutex.__data.__count = 0; |
354 | while (rtld_lock_count-- > 0) |
355 | __pthread_mutex_lock (&GL(dl_load_lock).mutex); |
356 | |
357 | GL(dl_make_stack_executable_hook) = &__make_stacks_executable; |
358 | #endif |
359 | |
360 | GL(dl_init_static_tls) = &__pthread_init_static_tls; |
361 | |
362 | GL(dl_wait_lookup_done) = &__wait_lookup_done; |
363 | |
364 | /* Register the fork generation counter with the libc. */ |
365 | #ifndef TLS_MULTIPLE_THREADS_IN_TCB |
366 | __libc_multiple_threads_ptr = |
367 | #endif |
368 | __libc_pthread_init (&__fork_generation, __reclaim_stacks, |
369 | ptr_pthread_functions); |
370 | |
371 | /* Determine whether the machine is SMP or not. */ |
372 | __is_smp = is_smp_system (); |
373 | |
374 | #if HAVE_TUNABLES |
375 | __pthread_tunables_init (); |
376 | #endif |
377 | } |
378 | strong_alias (__pthread_initialize_minimal_internal, |
379 | __pthread_initialize_minimal) |
380 | |
381 | |
382 | /* This function is internal (it has a GLIBC_PRIVATE) version, but it |
383 | is widely used (either via weak symbol, or dlsym) to obtain the |
384 | __static_tls_size value. This value is then used to adjust the |
385 | value of the stack size attribute, so that applications receive the |
386 | full requested stack size, not diminished by the TCB and static TLS |
387 | allocation on the stack. Once the TCB is separately allocated, |
388 | this function should be removed or renamed (if it is still |
389 | necessary at that point). */ |
390 | size_t |
391 | __pthread_get_minstack (const pthread_attr_t *attr) |
392 | { |
393 | return GLRO(dl_pagesize) + __static_tls_size + PTHREAD_STACK_MIN; |
394 | } |
395 | |