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 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 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 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 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 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