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/cdefs.h>
61 __FBSDID("$FreeBSD$");
62
63 #include <sys/syscall.h>
64 #include "namespace.h"
65 #include <errno.h>
66 #include <link.h>
67 #include <string.h>
68 #include <stdlib.h>
69 #include <unistd.h>
70 #include <pthread.h>
71 #include <spinlock.h>
72 #include "un-namespace.h"
73
74 #include "libc_private.h"
75 #include "rtld_lock.h"
76 #include "thr_private.h"
77
78 __weak_reference(_thr_atfork, _pthread_atfork);
79 __weak_reference(_thr_atfork, pthread_atfork);
80
81 int
_thr_atfork(void (* prepare)(void),void (* parent)(void),void (* child)(void))82 _thr_atfork(void (*prepare)(void), void (*parent)(void),
83 void (*child)(void))
84 {
85 struct pthread *curthread;
86 struct pthread_atfork *af;
87
88 _thr_check_init();
89
90 if ((af = malloc(sizeof(struct pthread_atfork))) == NULL)
91 return (ENOMEM);
92
93 curthread = _get_curthread();
94 af->prepare = prepare;
95 af->parent = parent;
96 af->child = child;
97 THR_CRITICAL_ENTER(curthread);
98 _thr_rwl_wrlock(&_thr_atfork_lock);
99 TAILQ_INSERT_TAIL(&_thr_atfork_list, af, qe);
100 _thr_rwl_unlock(&_thr_atfork_lock);
101 THR_CRITICAL_LEAVE(curthread);
102 return (0);
103 }
104
105 void
__pthread_cxa_finalize(struct dl_phdr_info * phdr_info)106 __pthread_cxa_finalize(struct dl_phdr_info *phdr_info)
107 {
108 atfork_head temp_list = TAILQ_HEAD_INITIALIZER(temp_list);
109 struct pthread *curthread;
110 struct pthread_atfork *af, *af1;
111
112 _thr_check_init();
113
114 curthread = _get_curthread();
115 THR_CRITICAL_ENTER(curthread);
116 _thr_rwl_wrlock(&_thr_atfork_lock);
117 TAILQ_FOREACH_SAFE(af, &_thr_atfork_list, qe, af1) {
118 if (__elf_phdr_match_addr(phdr_info, af->prepare) ||
119 __elf_phdr_match_addr(phdr_info, af->parent) ||
120 __elf_phdr_match_addr(phdr_info, af->child)) {
121 TAILQ_REMOVE(&_thr_atfork_list, af, qe);
122 TAILQ_INSERT_TAIL(&temp_list, af, qe);
123 }
124 }
125 _thr_rwl_unlock(&_thr_atfork_lock);
126 THR_CRITICAL_LEAVE(curthread);
127 while ((af = TAILQ_FIRST(&temp_list)) != NULL) {
128 TAILQ_REMOVE(&temp_list, af, qe);
129 free(af);
130 }
131 _thr_tsd_unload(phdr_info);
132 _thr_sigact_unload(phdr_info);
133 }
134
135 enum thr_fork_mode {
136 MODE_FORK,
137 MODE_PDFORK,
138 };
139
140 struct thr_fork_args {
141 enum thr_fork_mode mode;
142 void *fdp;
143 int flags;
144 };
145
146 static pid_t
thr_fork_impl(const struct thr_fork_args * a)147 thr_fork_impl(const struct thr_fork_args *a)
148 {
149 struct pthread *curthread;
150 struct pthread_atfork *af;
151 pid_t ret;
152 int errsave, cancelsave;
153 int was_threaded;
154 int rtld_locks[MAX_RTLD_LOCKS];
155
156 if (!_thr_is_inited()) {
157 switch (a->mode) {
158 case MODE_FORK:
159 return (__sys_fork());
160 case MODE_PDFORK:
161 return (__sys_pdfork(a->fdp, a->flags));
162 default:
163 errno = EDOOFUS;
164 return (-1);
165 }
166 }
167
168 curthread = _get_curthread();
169 cancelsave = curthread->no_cancel;
170 curthread->no_cancel = 1;
171 _thr_rwl_rdlock(&_thr_atfork_lock);
172
173 /* Run down atfork prepare handlers. */
174 TAILQ_FOREACH_REVERSE(af, &_thr_atfork_list, atfork_head, qe) {
175 if (af->prepare != NULL)
176 af->prepare();
177 }
178
179 /*
180 * Block all signals until we reach a safe point.
181 */
182 _thr_signal_block(curthread);
183 _thr_signal_prefork();
184
185 /*
186 * All bets are off as to what should happen soon if the parent
187 * process was not so kindly as to set up pthread fork hooks to
188 * relinquish all running threads.
189 */
190 if (_thr_isthreaded() != 0) {
191 was_threaded = 1;
192 __thr_malloc_prefork(curthread);
193 _malloc_prefork();
194 __thr_pshared_atfork_pre();
195 _rtld_atfork_pre(rtld_locks);
196 } else {
197 was_threaded = 0;
198 }
199
200 /*
201 * Fork a new process.
202 * There is no easy way to pre-resolve the __sys_fork symbol
203 * without performing the fork. Use the syscall(2)
204 * indirection, the syscall symbol is resolved in
205 * _thr_rtld_init() with side-effect free call.
206 */
207 switch (a->mode) {
208 case MODE_FORK:
209 ret = syscall(SYS_fork);
210 break;
211 case MODE_PDFORK:
212 ret = syscall(SYS_pdfork, a->fdp, a->flags);
213 break;
214 default:
215 ret = -1;
216 errno = EDOOFUS;
217 break;
218 }
219
220 if (ret == 0) {
221 /* Child process */
222 errsave = errno;
223 curthread->cancel_pending = 0;
224 curthread->flags &= ~(THR_FLAGS_NEED_SUSPEND|THR_FLAGS_DETACHED);
225
226 /*
227 * Thread list will be reinitialized, and later we call
228 * _libpthread_init(), it will add us back to list.
229 */
230 curthread->tlflags &= ~TLFLAGS_IN_TDLIST;
231
232 /* before thr_self() */
233 if (was_threaded)
234 __thr_malloc_postfork(curthread);
235
236 /* child is a new kernel thread. */
237 thr_self(&curthread->tid);
238
239 /* clear other threads locked us. */
240 _thr_umutex_init(&curthread->lock);
241 _mutex_fork(curthread);
242
243 _thr_signal_postfork_child();
244
245 if (was_threaded) {
246 _rtld_atfork_post(rtld_locks);
247 __thr_pshared_atfork_post();
248 }
249 _thr_setthreaded(0);
250
251 /* reinitalize library. */
252 _libpthread_init(curthread);
253
254 /* atfork is reinitialized by _libpthread_init()! */
255 _thr_rwl_rdlock(&_thr_atfork_lock);
256
257 if (was_threaded) {
258 _thr_setthreaded(1);
259 _malloc_postfork();
260 _thr_setthreaded(0);
261 }
262
263 /* Ready to continue, unblock signals. */
264 _thr_signal_unblock(curthread);
265
266 /* Run down atfork child handlers. */
267 TAILQ_FOREACH(af, &_thr_atfork_list, qe) {
268 if (af->child != NULL)
269 af->child();
270 }
271 _thr_rwlock_unlock(&_thr_atfork_lock);
272 curthread->no_cancel = cancelsave;
273 } else {
274 /* Parent process */
275 errsave = errno;
276
277 _thr_signal_postfork();
278
279 if (was_threaded) {
280 __thr_malloc_postfork(curthread);
281 _rtld_atfork_post(rtld_locks);
282 __thr_pshared_atfork_post();
283 _malloc_postfork();
284 }
285
286 /* Ready to continue, unblock signals. */
287 _thr_signal_unblock(curthread);
288
289 /* Run down atfork parent handlers. */
290 TAILQ_FOREACH(af, &_thr_atfork_list, qe) {
291 if (af->parent != NULL)
292 af->parent();
293 }
294
295 _thr_rwlock_unlock(&_thr_atfork_lock);
296 curthread->no_cancel = cancelsave;
297 /* test async cancel */
298 if (curthread->cancel_async)
299 _thr_testcancel(curthread);
300 }
301 errno = errsave;
302
303 return (ret);
304 }
305
306 __weak_reference(__thr_fork, _fork);
307
308 pid_t
__thr_fork(void)309 __thr_fork(void)
310 {
311 struct thr_fork_args a;
312
313 a.mode = MODE_FORK;
314 return (thr_fork_impl(&a));
315 }
316
317 pid_t
__thr_pdfork(int * fdp,int flags)318 __thr_pdfork(int *fdp, int flags)
319 {
320 struct thr_fork_args a;
321
322 a.mode = MODE_PDFORK;
323 a.fdp = fdp;
324 a.flags = flags;
325 return (thr_fork_impl(&a));
326 }
327