1 /*
2 * Copyright (c) 2005 David Xu <davidxu@freebsd.org>
3 * Copyright (c) 2003 Daniel Eischen <deischen@freebsd.org>
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 <jb@cimlogic.com.au>
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 if ((af = malloc(sizeof(struct pthread_atfork))) == NULL)
88 return (ENOMEM);
89
90 af->prepare = prepare;
91 af->parent = parent;
92 af->child = child;
93
94 if (_thr_initial != NULL) {
95 curthread = _get_curthread();
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 } else {
102 TAILQ_INSERT_TAIL(&_thr_atfork_list, af, qe);
103 }
104
105 return (0);
106 }
107
108 void
__pthread_cxa_finalize(struct dl_phdr_info * phdr_info)109 __pthread_cxa_finalize(struct dl_phdr_info *phdr_info)
110 {
111 atfork_head temp_list = TAILQ_HEAD_INITIALIZER(temp_list);
112 struct pthread *curthread;
113 struct pthread_atfork *af, *af1;
114
115 _thr_check_init();
116
117 curthread = _get_curthread();
118 THR_CRITICAL_ENTER(curthread);
119 _thr_rwl_wrlock(&_thr_atfork_lock);
120 TAILQ_FOREACH_SAFE(af, &_thr_atfork_list, qe, af1) {
121 if (__elf_phdr_match_addr(phdr_info, af->prepare) ||
122 __elf_phdr_match_addr(phdr_info, af->parent) ||
123 __elf_phdr_match_addr(phdr_info, af->child)) {
124 TAILQ_REMOVE(&_thr_atfork_list, af, qe);
125 TAILQ_INSERT_TAIL(&temp_list, af, qe);
126 }
127 }
128 _thr_rwl_unlock(&_thr_atfork_lock);
129 THR_CRITICAL_LEAVE(curthread);
130 while ((af = TAILQ_FIRST(&temp_list)) != NULL) {
131 TAILQ_REMOVE(&temp_list, af, qe);
132 free(af);
133 }
134 _thr_tsd_unload(phdr_info);
135 _thr_sigact_unload(phdr_info);
136 }
137
138 enum thr_fork_mode {
139 MODE_FORK,
140 MODE_PDFORK,
141 };
142
143 struct thr_fork_args {
144 enum thr_fork_mode mode;
145 void *fdp;
146 int flags;
147 };
148
149 static pid_t
thr_fork_impl(const struct thr_fork_args * a)150 thr_fork_impl(const struct thr_fork_args *a)
151 {
152 struct pthread *curthread;
153 struct pthread_atfork *af;
154 pid_t ret;
155 int errsave, cancelsave;
156 int was_threaded;
157 int rtld_locks[MAX_RTLD_LOCKS];
158
159 if (!_thr_is_inited()) {
160 switch (a->mode) {
161 case MODE_FORK:
162 return (__sys_fork());
163 case MODE_PDFORK:
164 return (__sys_pdfork(a->fdp, a->flags));
165 default:
166 errno = EDOOFUS;
167 return (-1);
168 }
169 }
170
171 curthread = _get_curthread();
172 cancelsave = curthread->no_cancel;
173 curthread->no_cancel = 1;
174 _thr_rwl_rdlock(&_thr_atfork_lock);
175
176 /* Run down atfork prepare handlers. */
177 TAILQ_FOREACH_REVERSE(af, &_thr_atfork_list, atfork_head, qe) {
178 if (af->prepare != NULL)
179 af->prepare();
180 }
181
182 /*
183 * Block all signals until we reach a safe point.
184 */
185 _thr_signal_block(curthread);
186 _thr_signal_prefork();
187
188 /*
189 * All bets are off as to what should happen soon if the parent
190 * process was not so kindly as to set up pthread fork hooks to
191 * relinquish all running threads.
192 */
193 if (_thr_isthreaded() != 0) {
194 was_threaded = 1;
195 __thr_malloc_prefork(curthread);
196 _malloc_prefork();
197 __thr_pshared_atfork_pre();
198 _rtld_atfork_pre(rtld_locks);
199 } else {
200 was_threaded = 0;
201 }
202
203 /*
204 * Fork a new process.
205 * There is no easy way to pre-resolve the __sys_fork symbol
206 * without performing the fork. Use the syscall(2)
207 * indirection, the syscall symbol is resolved in
208 * _thr_rtld_init() with side-effect free call.
209 */
210 switch (a->mode) {
211 case MODE_FORK:
212 ret = syscall(SYS_fork);
213 break;
214 case MODE_PDFORK:
215 ret = syscall(SYS_pdfork, a->fdp, a->flags);
216 break;
217 default:
218 ret = -1;
219 errno = EDOOFUS;
220 break;
221 }
222
223 if (ret == 0) {
224 /* Child process */
225 errsave = errno;
226 curthread->cancel_pending = 0;
227 curthread->flags &= ~(THR_FLAGS_NEED_SUSPEND|THR_FLAGS_DETACHED);
228
229 /*
230 * Thread list will be reinitialized, and later we call
231 * _libpthread_init(), it will add us back to list.
232 */
233 curthread->tlflags &= ~TLFLAGS_IN_TDLIST;
234
235 /* before thr_self() */
236 if (was_threaded)
237 __thr_malloc_postfork(curthread);
238
239 /* child is a new kernel thread. */
240 thr_self(&curthread->tid);
241
242 /* clear other threads locked us. */
243 _thr_umutex_init(&curthread->lock);
244 _mutex_fork(curthread);
245
246 _thr_signal_postfork_child();
247
248 if (was_threaded) {
249 _thr_after_fork = true;
250 _rtld_atfork_post(rtld_locks);
251 _thr_after_fork = false;
252 __thr_pshared_atfork_post();
253 }
254 _thr_setthreaded(0);
255
256 /* reinitalize library. */
257 _libpthread_init(curthread);
258
259 /* atfork is reinitialized by _libpthread_init()! */
260 _thr_rwl_rdlock(&_thr_atfork_lock);
261
262 if (was_threaded) {
263 _thr_setthreaded(1);
264 _malloc_postfork();
265 _thr_setthreaded(0);
266 }
267
268 /* Ready to continue, unblock signals. */
269 _thr_signal_unblock(curthread);
270
271 /* Run down atfork child handlers. */
272 TAILQ_FOREACH(af, &_thr_atfork_list, qe) {
273 if (af->child != NULL)
274 af->child();
275 }
276 _thr_rwlock_unlock(&_thr_atfork_lock);
277 curthread->no_cancel = cancelsave;
278 } else {
279 /* Parent process */
280 errsave = errno;
281
282 _thr_signal_postfork();
283
284 if (was_threaded) {
285 __thr_malloc_postfork(curthread);
286 _rtld_atfork_post(rtld_locks);
287 __thr_pshared_atfork_post();
288 _malloc_postfork();
289 }
290
291 /* Ready to continue, unblock signals. */
292 _thr_signal_unblock(curthread);
293
294 /* Run down atfork parent handlers. */
295 TAILQ_FOREACH(af, &_thr_atfork_list, qe) {
296 if (af->parent != NULL)
297 af->parent();
298 }
299
300 _thr_rwlock_unlock(&_thr_atfork_lock);
301 curthread->no_cancel = cancelsave;
302 /* test async cancel */
303 if (curthread->cancel_async)
304 _thr_testcancel(curthread);
305 }
306 errno = errsave;
307
308 return (ret);
309 }
310
311 __weak_reference(__thr_fork, _fork);
312
313 pid_t
__thr_fork(void)314 __thr_fork(void)
315 {
316 struct thr_fork_args a;
317
318 a.mode = MODE_FORK;
319 return (thr_fork_impl(&a));
320 }
321
322 pid_t
__thr_pdfork(int * fdp,int flags)323 __thr_pdfork(int *fdp, int flags)
324 {
325 struct thr_fork_args a;
326
327 a.mode = MODE_PDFORK;
328 a.fdp = fdp;
329 a.flags = flags;
330 return (thr_fork_impl(&a));
331 }
332