1 /*
2 * Copyright (c) 2005 David Xu <[email protected]>
3 * Copyright (c) 2003 Daniel Eischen <[email protected]>
4 * All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 * 2. Neither the name of the author nor the names of any co-contributors
12 * may be used to endorse or promote products derived from this software
13 * without specific prior written permission.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
16 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
18 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
19 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
21 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
22 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
23 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
24 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
25 * SUCH DAMAGE.
26 */
27
28 /*-
29 * SPDX-License-Identifier: BSD-3-Clause
30 *
31 * Copyright (c) 1995-1998 John Birrell <[email protected]>
32 * All rights reserved.
33 *
34 * Redistribution and use in source and binary forms, with or without
35 * modification, are permitted provided that the following conditions
36 * are met:
37 * 1. Redistributions of source code must retain the above copyright
38 * notice, this list of conditions and the following disclaimer.
39 * 2. Redistributions in binary form must reproduce the above copyright
40 * notice, this list of conditions and the following disclaimer in the
41 * documentation and/or other materials provided with the distribution.
42 * 3. Neither the name of the author nor the names of any co-contributors
43 * may be used to endorse or promote products derived from this software
44 * without specific prior written permission.
45 *
46 * THIS SOFTWARE IS PROVIDED BY JOHN BIRRELL AND CONTRIBUTORS ``AS IS'' AND
47 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
48 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
49 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
50 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
51 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
52 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
53 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
54 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
55 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
56 * SUCH DAMAGE.
57 *
58 */
59
60 #include <sys/syscall.h>
61 #include "namespace.h"
62 #include <errno.h>
63 #include <link.h>
64 #include <string.h>
65 #include <stdlib.h>
66 #include <unistd.h>
67 #include <pthread.h>
68 #include <spinlock.h>
69 #include "un-namespace.h"
70
71 #include "libc_private.h"
72 #include "rtld_lock.h"
73 #include "thr_private.h"
74
75 __weak_reference(_thr_atfork, _pthread_atfork);
76 __weak_reference(_thr_atfork, pthread_atfork);
77
78 bool _thr_after_fork = false;
79
80 int
_thr_atfork(void (* prepare)(void),void (* parent)(void),void (* child)(void))81 _thr_atfork(void (*prepare)(void), void (*parent)(void),
82 void (*child)(void))
83 {
84 struct pthread *curthread;
85 struct pthread_atfork *af;
86
87 _thr_check_init();
88
89 if ((af = malloc(sizeof(struct pthread_atfork))) == NULL)
90 return (ENOMEM);
91
92 curthread = _get_curthread();
93 af->prepare = prepare;
94 af->parent = parent;
95 af->child = child;
96 THR_CRITICAL_ENTER(curthread);
97 _thr_rwl_wrlock(&_thr_atfork_lock);
98 TAILQ_INSERT_TAIL(&_thr_atfork_list, af, qe);
99 _thr_rwl_unlock(&_thr_atfork_lock);
100 THR_CRITICAL_LEAVE(curthread);
101 return (0);
102 }
103
104 void
__pthread_cxa_finalize(struct dl_phdr_info * phdr_info)105 __pthread_cxa_finalize(struct dl_phdr_info *phdr_info)
106 {
107 atfork_head temp_list = TAILQ_HEAD_INITIALIZER(temp_list);
108 struct pthread *curthread;
109 struct pthread_atfork *af, *af1;
110
111 _thr_check_init();
112
113 curthread = _get_curthread();
114 THR_CRITICAL_ENTER(curthread);
115 _thr_rwl_wrlock(&_thr_atfork_lock);
116 TAILQ_FOREACH_SAFE(af, &_thr_atfork_list, qe, af1) {
117 if (__elf_phdr_match_addr(phdr_info, af->prepare) ||
118 __elf_phdr_match_addr(phdr_info, af->parent) ||
119 __elf_phdr_match_addr(phdr_info, af->child)) {
120 TAILQ_REMOVE(&_thr_atfork_list, af, qe);
121 TAILQ_INSERT_TAIL(&temp_list, af, qe);
122 }
123 }
124 _thr_rwl_unlock(&_thr_atfork_lock);
125 THR_CRITICAL_LEAVE(curthread);
126 while ((af = TAILQ_FIRST(&temp_list)) != NULL) {
127 TAILQ_REMOVE(&temp_list, af, qe);
128 free(af);
129 }
130 _thr_tsd_unload(phdr_info);
131 _thr_sigact_unload(phdr_info);
132 }
133
134 enum thr_fork_mode {
135 MODE_FORK,
136 MODE_PDFORK,
137 };
138
139 struct thr_fork_args {
140 enum thr_fork_mode mode;
141 void *fdp;
142 int flags;
143 };
144
145 static pid_t
thr_fork_impl(const struct thr_fork_args * a)146 thr_fork_impl(const struct thr_fork_args *a)
147 {
148 struct pthread *curthread;
149 struct pthread_atfork *af;
150 pid_t ret;
151 int errsave, cancelsave;
152 int was_threaded;
153 int rtld_locks[MAX_RTLD_LOCKS];
154
155 if (!_thr_is_inited()) {
156 switch (a->mode) {
157 case MODE_FORK:
158 return (__sys_fork());
159 case MODE_PDFORK:
160 return (__sys_pdfork(a->fdp, a->flags));
161 default:
162 errno = EDOOFUS;
163 return (-1);
164 }
165 }
166
167 curthread = _get_curthread();
168 cancelsave = curthread->no_cancel;
169 curthread->no_cancel = 1;
170 _thr_rwl_rdlock(&_thr_atfork_lock);
171
172 /* Run down atfork prepare handlers. */
173 TAILQ_FOREACH_REVERSE(af, &_thr_atfork_list, atfork_head, qe) {
174 if (af->prepare != NULL)
175 af->prepare();
176 }
177
178 /*
179 * Block all signals until we reach a safe point.
180 */
181 _thr_signal_block(curthread);
182 _thr_signal_prefork();
183
184 /*
185 * All bets are off as to what should happen soon if the parent
186 * process was not so kindly as to set up pthread fork hooks to
187 * relinquish all running threads.
188 */
189 if (_thr_isthreaded() != 0) {
190 was_threaded = 1;
191 __thr_malloc_prefork(curthread);
192 _malloc_prefork();
193 __thr_pshared_atfork_pre();
194 _rtld_atfork_pre(rtld_locks);
195 } else {
196 was_threaded = 0;
197 }
198
199 /*
200 * Fork a new process.
201 * There is no easy way to pre-resolve the __sys_fork symbol
202 * without performing the fork. Use the syscall(2)
203 * indirection, the syscall symbol is resolved in
204 * _thr_rtld_init() with side-effect free call.
205 */
206 switch (a->mode) {
207 case MODE_FORK:
208 ret = syscall(SYS_fork);
209 break;
210 case MODE_PDFORK:
211 ret = syscall(SYS_pdfork, a->fdp, a->flags);
212 break;
213 default:
214 ret = -1;
215 errno = EDOOFUS;
216 break;
217 }
218
219 if (ret == 0) {
220 /* Child process */
221 errsave = errno;
222 curthread->cancel_pending = 0;
223 curthread->flags &= ~(THR_FLAGS_NEED_SUSPEND|THR_FLAGS_DETACHED);
224
225 /*
226 * Thread list will be reinitialized, and later we call
227 * _libpthread_init(), it will add us back to list.
228 */
229 curthread->tlflags &= ~TLFLAGS_IN_TDLIST;
230
231 /* before thr_self() */
232 if (was_threaded)
233 __thr_malloc_postfork(curthread);
234
235 /* child is a new kernel thread. */
236 thr_self(&curthread->tid);
237
238 /* clear other threads locked us. */
239 _thr_umutex_init(&curthread->lock);
240 _mutex_fork(curthread);
241
242 _thr_signal_postfork_child();
243
244 if (was_threaded) {
245 _thr_after_fork = true;
246 _rtld_atfork_post(rtld_locks);
247 _thr_after_fork = false;
248 __thr_pshared_atfork_post();
249 }
250 _thr_setthreaded(0);
251
252 /* reinitalize library. */
253 _libpthread_init(curthread);
254
255 /* atfork is reinitialized by _libpthread_init()! */
256 _thr_rwl_rdlock(&_thr_atfork_lock);
257
258 if (was_threaded) {
259 _thr_setthreaded(1);
260 _malloc_postfork();
261 _thr_setthreaded(0);
262 }
263
264 /* Ready to continue, unblock signals. */
265 _thr_signal_unblock(curthread);
266
267 /* Run down atfork child handlers. */
268 TAILQ_FOREACH(af, &_thr_atfork_list, qe) {
269 if (af->child != NULL)
270 af->child();
271 }
272 _thr_rwlock_unlock(&_thr_atfork_lock);
273 curthread->no_cancel = cancelsave;
274 } else {
275 /* Parent process */
276 errsave = errno;
277
278 _thr_signal_postfork();
279
280 if (was_threaded) {
281 __thr_malloc_postfork(curthread);
282 _rtld_atfork_post(rtld_locks);
283 __thr_pshared_atfork_post();
284 _malloc_postfork();
285 }
286
287 /* Ready to continue, unblock signals. */
288 _thr_signal_unblock(curthread);
289
290 /* Run down atfork parent handlers. */
291 TAILQ_FOREACH(af, &_thr_atfork_list, qe) {
292 if (af->parent != NULL)
293 af->parent();
294 }
295
296 _thr_rwlock_unlock(&_thr_atfork_lock);
297 curthread->no_cancel = cancelsave;
298 /* test async cancel */
299 if (curthread->cancel_async)
300 _thr_testcancel(curthread);
301 }
302 errno = errsave;
303
304 return (ret);
305 }
306
307 __weak_reference(__thr_fork, _fork);
308
309 pid_t
__thr_fork(void)310 __thr_fork(void)
311 {
312 struct thr_fork_args a;
313
314 a.mode = MODE_FORK;
315 return (thr_fork_impl(&a));
316 }
317
318 pid_t
__thr_pdfork(int * fdp,int flags)319 __thr_pdfork(int *fdp, int flags)
320 {
321 struct thr_fork_args a;
322
323 a.mode = MODE_PDFORK;
324 a.fdp = fdp;
325 a.flags = flags;
326 return (thr_fork_impl(&a));
327 }
328