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 #include <sys/syscall.h> 62 #include "namespace.h" 63 #include <errno.h> 64 #include <link.h> 65 #include <string.h> 66 #include <stdlib.h> 67 #include <unistd.h> 68 #include <pthread.h> 69 #include <spinlock.h> 70 #include "un-namespace.h" 71 72 #include "libc_private.h" 73 #include "rtld_lock.h" 74 #include "thr_private.h" 75 76 __weak_reference(_thr_atfork, _pthread_atfork); 77 __weak_reference(_thr_atfork, pthread_atfork); 78 79 bool _thr_after_fork = false; 80 81 int 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 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 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 _thr_after_fork = true; 247 _rtld_atfork_post(rtld_locks); 248 _thr_after_fork = false; 249 __thr_pshared_atfork_post(); 250 } 251 _thr_setthreaded(0); 252 253 /* reinitalize library. */ 254 _libpthread_init(curthread); 255 256 /* atfork is reinitialized by _libpthread_init()! */ 257 _thr_rwl_rdlock(&_thr_atfork_lock); 258 259 if (was_threaded) { 260 _thr_setthreaded(1); 261 _malloc_postfork(); 262 _thr_setthreaded(0); 263 } 264 265 /* Ready to continue, unblock signals. */ 266 _thr_signal_unblock(curthread); 267 268 /* Run down atfork child handlers. */ 269 TAILQ_FOREACH(af, &_thr_atfork_list, qe) { 270 if (af->child != NULL) 271 af->child(); 272 } 273 _thr_rwlock_unlock(&_thr_atfork_lock); 274 curthread->no_cancel = cancelsave; 275 } else { 276 /* Parent process */ 277 errsave = errno; 278 279 _thr_signal_postfork(); 280 281 if (was_threaded) { 282 __thr_malloc_postfork(curthread); 283 _rtld_atfork_post(rtld_locks); 284 __thr_pshared_atfork_post(); 285 _malloc_postfork(); 286 } 287 288 /* Ready to continue, unblock signals. */ 289 _thr_signal_unblock(curthread); 290 291 /* Run down atfork parent handlers. */ 292 TAILQ_FOREACH(af, &_thr_atfork_list, qe) { 293 if (af->parent != NULL) 294 af->parent(); 295 } 296 297 _thr_rwlock_unlock(&_thr_atfork_lock); 298 curthread->no_cancel = cancelsave; 299 /* test async cancel */ 300 if (curthread->cancel_async) 301 _thr_testcancel(curthread); 302 } 303 errno = errsave; 304 305 return (ret); 306 } 307 308 __weak_reference(__thr_fork, _fork); 309 310 pid_t 311 __thr_fork(void) 312 { 313 struct thr_fork_args a; 314 315 a.mode = MODE_FORK; 316 return (thr_fork_impl(&a)); 317 } 318 319 pid_t 320 __thr_pdfork(int *fdp, int flags) 321 { 322 struct thr_fork_args a; 323 324 a.mode = MODE_PDFORK; 325 a.fdp = fdp; 326 a.flags = flags; 327 return (thr_fork_impl(&a)); 328 } 329