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/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 bool _thr_after_fork = false; 82 83 int 84 _thr_atfork(void (*prepare)(void), void (*parent)(void), 85 void (*child)(void)) 86 { 87 struct pthread *curthread; 88 struct pthread_atfork *af; 89 90 _thr_check_init(); 91 92 if ((af = malloc(sizeof(struct pthread_atfork))) == NULL) 93 return (ENOMEM); 94 95 curthread = _get_curthread(); 96 af->prepare = prepare; 97 af->parent = parent; 98 af->child = child; 99 THR_CRITICAL_ENTER(curthread); 100 _thr_rwl_wrlock(&_thr_atfork_lock); 101 TAILQ_INSERT_TAIL(&_thr_atfork_list, af, qe); 102 _thr_rwl_unlock(&_thr_atfork_lock); 103 THR_CRITICAL_LEAVE(curthread); 104 return (0); 105 } 106 107 void 108 __pthread_cxa_finalize(struct dl_phdr_info *phdr_info) 109 { 110 atfork_head temp_list = TAILQ_HEAD_INITIALIZER(temp_list); 111 struct pthread *curthread; 112 struct pthread_atfork *af, *af1; 113 114 _thr_check_init(); 115 116 curthread = _get_curthread(); 117 THR_CRITICAL_ENTER(curthread); 118 _thr_rwl_wrlock(&_thr_atfork_lock); 119 TAILQ_FOREACH_SAFE(af, &_thr_atfork_list, qe, af1) { 120 if (__elf_phdr_match_addr(phdr_info, af->prepare) || 121 __elf_phdr_match_addr(phdr_info, af->parent) || 122 __elf_phdr_match_addr(phdr_info, af->child)) { 123 TAILQ_REMOVE(&_thr_atfork_list, af, qe); 124 TAILQ_INSERT_TAIL(&temp_list, af, qe); 125 } 126 } 127 _thr_rwl_unlock(&_thr_atfork_lock); 128 THR_CRITICAL_LEAVE(curthread); 129 while ((af = TAILQ_FIRST(&temp_list)) != NULL) { 130 TAILQ_REMOVE(&temp_list, af, qe); 131 free(af); 132 } 133 _thr_tsd_unload(phdr_info); 134 _thr_sigact_unload(phdr_info); 135 } 136 137 enum thr_fork_mode { 138 MODE_FORK, 139 MODE_PDFORK, 140 }; 141 142 struct thr_fork_args { 143 enum thr_fork_mode mode; 144 void *fdp; 145 int flags; 146 }; 147 148 static pid_t 149 thr_fork_impl(const struct thr_fork_args *a) 150 { 151 struct pthread *curthread; 152 struct pthread_atfork *af; 153 pid_t ret; 154 int errsave, cancelsave; 155 int was_threaded; 156 int rtld_locks[MAX_RTLD_LOCKS]; 157 158 if (!_thr_is_inited()) { 159 switch (a->mode) { 160 case MODE_FORK: 161 return (__sys_fork()); 162 case MODE_PDFORK: 163 return (__sys_pdfork(a->fdp, a->flags)); 164 default: 165 errno = EDOOFUS; 166 return (-1); 167 } 168 } 169 170 curthread = _get_curthread(); 171 cancelsave = curthread->no_cancel; 172 curthread->no_cancel = 1; 173 _thr_rwl_rdlock(&_thr_atfork_lock); 174 175 /* Run down atfork prepare handlers. */ 176 TAILQ_FOREACH_REVERSE(af, &_thr_atfork_list, atfork_head, qe) { 177 if (af->prepare != NULL) 178 af->prepare(); 179 } 180 181 /* 182 * Block all signals until we reach a safe point. 183 */ 184 _thr_signal_block(curthread); 185 _thr_signal_prefork(); 186 187 /* 188 * All bets are off as to what should happen soon if the parent 189 * process was not so kindly as to set up pthread fork hooks to 190 * relinquish all running threads. 191 */ 192 if (_thr_isthreaded() != 0) { 193 was_threaded = 1; 194 __thr_malloc_prefork(curthread); 195 _malloc_prefork(); 196 __thr_pshared_atfork_pre(); 197 _rtld_atfork_pre(rtld_locks); 198 } else { 199 was_threaded = 0; 200 } 201 202 /* 203 * Fork a new process. 204 * There is no easy way to pre-resolve the __sys_fork symbol 205 * without performing the fork. Use the syscall(2) 206 * indirection, the syscall symbol is resolved in 207 * _thr_rtld_init() with side-effect free call. 208 */ 209 switch (a->mode) { 210 case MODE_FORK: 211 ret = syscall(SYS_fork); 212 break; 213 case MODE_PDFORK: 214 ret = syscall(SYS_pdfork, a->fdp, a->flags); 215 break; 216 default: 217 ret = -1; 218 errno = EDOOFUS; 219 break; 220 } 221 222 if (ret == 0) { 223 /* Child process */ 224 errsave = errno; 225 curthread->cancel_pending = 0; 226 curthread->flags &= ~(THR_FLAGS_NEED_SUSPEND|THR_FLAGS_DETACHED); 227 228 /* 229 * Thread list will be reinitialized, and later we call 230 * _libpthread_init(), it will add us back to list. 231 */ 232 curthread->tlflags &= ~TLFLAGS_IN_TDLIST; 233 234 /* before thr_self() */ 235 if (was_threaded) 236 __thr_malloc_postfork(curthread); 237 238 /* child is a new kernel thread. */ 239 thr_self(&curthread->tid); 240 241 /* clear other threads locked us. */ 242 _thr_umutex_init(&curthread->lock); 243 _mutex_fork(curthread); 244 245 _thr_signal_postfork_child(); 246 247 if (was_threaded) { 248 _thr_after_fork = true; 249 _rtld_atfork_post(rtld_locks); 250 _thr_after_fork = false; 251 __thr_pshared_atfork_post(); 252 } 253 _thr_setthreaded(0); 254 255 /* reinitalize library. */ 256 _libpthread_init(curthread); 257 258 /* atfork is reinitialized by _libpthread_init()! */ 259 _thr_rwl_rdlock(&_thr_atfork_lock); 260 261 if (was_threaded) { 262 _thr_setthreaded(1); 263 _malloc_postfork(); 264 _thr_setthreaded(0); 265 } 266 267 /* Ready to continue, unblock signals. */ 268 _thr_signal_unblock(curthread); 269 270 /* Run down atfork child handlers. */ 271 TAILQ_FOREACH(af, &_thr_atfork_list, qe) { 272 if (af->child != NULL) 273 af->child(); 274 } 275 _thr_rwlock_unlock(&_thr_atfork_lock); 276 curthread->no_cancel = cancelsave; 277 } else { 278 /* Parent process */ 279 errsave = errno; 280 281 _thr_signal_postfork(); 282 283 if (was_threaded) { 284 __thr_malloc_postfork(curthread); 285 _rtld_atfork_post(rtld_locks); 286 __thr_pshared_atfork_post(); 287 _malloc_postfork(); 288 } 289 290 /* Ready to continue, unblock signals. */ 291 _thr_signal_unblock(curthread); 292 293 /* Run down atfork parent handlers. */ 294 TAILQ_FOREACH(af, &_thr_atfork_list, qe) { 295 if (af->parent != NULL) 296 af->parent(); 297 } 298 299 _thr_rwlock_unlock(&_thr_atfork_lock); 300 curthread->no_cancel = cancelsave; 301 /* test async cancel */ 302 if (curthread->cancel_async) 303 _thr_testcancel(curthread); 304 } 305 errno = errsave; 306 307 return (ret); 308 } 309 310 __weak_reference(__thr_fork, _fork); 311 312 pid_t 313 __thr_fork(void) 314 { 315 struct thr_fork_args a; 316 317 a.mode = MODE_FORK; 318 return (thr_fork_impl(&a)); 319 } 320 321 pid_t 322 __thr_pdfork(int *fdp, int flags) 323 { 324 struct thr_fork_args a; 325 326 a.mode = MODE_PDFORK; 327 a.fdp = fdp; 328 a.flags = flags; 329 return (thr_fork_impl(&a)); 330 } 331