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