1 /* $NetBSD: kern_exit.c,v 1.267 2016/11/13 15:25:01 christos Exp $ */ 2 3 /*- 4 * Copyright (c) 1998, 1999, 2006, 2007, 2008 The NetBSD Foundation, Inc. 5 * All rights reserved. 6 * 7 * This code is derived from software contributed to The NetBSD Foundation 8 * by Jason R. Thorpe of the Numerical Aerospace Simulation Facility, 9 * NASA Ames Research Center, and by Andrew Doran. 10 * 11 * Redistribution and use in source and binary forms, with or without 12 * modification, are permitted provided that the following conditions 13 * are met: 14 * 1. Redistributions of source code must retain the above copyright 15 * notice, this list of conditions and the following disclaimer. 16 * 2. Redistributions in binary form must reproduce the above copyright 17 * notice, this list of conditions and the following disclaimer in the 18 * documentation and/or other materials provided with the distribution. 19 * 20 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 21 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 22 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 23 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 24 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 25 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 26 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 27 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 28 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 29 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 30 * POSSIBILITY OF SUCH DAMAGE. 31 */ 32 33 /* 34 * Copyright (c) 1982, 1986, 1989, 1991, 1993 35 * The Regents of the University of California. All rights reserved. 36 * (c) UNIX System Laboratories, Inc. 37 * All or some portions of this file are derived from material licensed 38 * to the University of California by American Telephone and Telegraph 39 * Co. or Unix System Laboratories, Inc. and are reproduced herein with 40 * the permission of UNIX System Laboratories, Inc. 41 * 42 * Redistribution and use in source and binary forms, with or without 43 * modification, are permitted provided that the following conditions 44 * are met: 45 * 1. Redistributions of source code must retain the above copyright 46 * notice, this list of conditions and the following disclaimer. 47 * 2. Redistributions in binary form must reproduce the above copyright 48 * notice, this list of conditions and the following disclaimer in the 49 * documentation and/or other materials provided with the distribution. 50 * 3. Neither the name of the University nor the names of its contributors 51 * may be used to endorse or promote products derived from this software 52 * without specific prior written permission. 53 * 54 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 55 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 56 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 57 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 58 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 59 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 60 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 61 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 62 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 63 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 64 * SUCH DAMAGE. 65 * 66 * @(#)kern_exit.c 8.10 (Berkeley) 2/23/95 67 */ 68 69 #include <sys/cdefs.h> 70 __KERNEL_RCSID(0, "$NetBSD: kern_exit.c,v 1.267 2016/11/13 15:25:01 christos Exp $"); 71 72 #include "opt_ktrace.h" 73 #include "opt_dtrace.h" 74 #include "opt_perfctrs.h" 75 #include "opt_sysv.h" 76 77 #include <sys/param.h> 78 #include <sys/systm.h> 79 #include <sys/ioctl.h> 80 #include <sys/tty.h> 81 #include <sys/time.h> 82 #include <sys/resource.h> 83 #include <sys/kernel.h> 84 #include <sys/proc.h> 85 #include <sys/buf.h> 86 #include <sys/wait.h> 87 #include <sys/file.h> 88 #include <sys/vnode.h> 89 #include <sys/syslog.h> 90 #include <sys/pool.h> 91 #include <sys/uidinfo.h> 92 #if defined(PERFCTRS) 93 #include <sys/pmc.h> 94 #endif 95 #include <sys/ptrace.h> 96 #include <sys/acct.h> 97 #include <sys/filedesc.h> 98 #include <sys/ras.h> 99 #include <sys/signalvar.h> 100 #include <sys/sched.h> 101 #include <sys/mount.h> 102 #include <sys/syscallargs.h> 103 #include <sys/kauth.h> 104 #include <sys/sleepq.h> 105 #include <sys/lockdebug.h> 106 #include <sys/ktrace.h> 107 #include <sys/cpu.h> 108 #include <sys/lwpctl.h> 109 #include <sys/atomic.h> 110 #include <sys/sdt.h> 111 112 #include <uvm/uvm_extern.h> 113 114 #ifdef DEBUG_EXIT 115 int debug_exit = 0; 116 #define DPRINTF(x) if (debug_exit) printf x 117 #else 118 #define DPRINTF(x) 119 #endif 120 121 static int find_stopped_child(struct proc *, idtype_t, id_t, int, 122 struct proc **, struct wrusage *, siginfo_t *); 123 static void proc_free(struct proc *, struct wrusage *); 124 125 /* 126 * DTrace SDT provider definitions 127 */ 128 SDT_PROVIDER_DECLARE(proc); 129 SDT_PROBE_DEFINE1(proc, kernel, , exit, "int"); 130 131 /* 132 * Fill in the appropriate signal information, and signal the parent. 133 */ 134 /* XXX noclone works around a gcc 4.5 bug on arm */ 135 static void __noclone 136 exit_psignal(struct proc *p, struct proc *pp, ksiginfo_t *ksi) 137 { 138 139 KSI_INIT(ksi); 140 if ((ksi->ksi_signo = P_EXITSIG(p)) == SIGCHLD) { 141 if (p->p_xsig) { 142 if (p->p_sflag & PS_COREDUMP) 143 ksi->ksi_code = CLD_DUMPED; 144 else 145 ksi->ksi_code = CLD_KILLED; 146 ksi->ksi_status = p->p_xsig; 147 } else { 148 ksi->ksi_code = CLD_EXITED; 149 ksi->ksi_status = p->p_xexit; 150 } 151 } else { 152 ksi->ksi_code = SI_USER; 153 ksi->ksi_status = p->p_xsig; 154 } 155 /* 156 * We fill those in, even for non-SIGCHLD. 157 * It's safe to access p->p_cred unlocked here. 158 */ 159 ksi->ksi_pid = p->p_pid; 160 ksi->ksi_uid = kauth_cred_geteuid(p->p_cred); 161 /* XXX: is this still valid? */ 162 ksi->ksi_utime = p->p_stats->p_ru.ru_utime.tv_sec; 163 ksi->ksi_stime = p->p_stats->p_ru.ru_stime.tv_sec; 164 } 165 166 /* 167 * exit -- 168 * Death of process. 169 */ 170 int 171 sys_exit(struct lwp *l, const struct sys_exit_args *uap, register_t *retval) 172 { 173 /* { 174 syscallarg(int) rval; 175 } */ 176 struct proc *p = l->l_proc; 177 178 /* Don't call exit1() multiple times in the same process. */ 179 mutex_enter(p->p_lock); 180 if (p->p_sflag & PS_WEXIT) { 181 mutex_exit(p->p_lock); 182 lwp_exit(l); 183 } 184 185 /* exit1() will release the mutex. */ 186 exit1(l, SCARG(uap, rval), 0); 187 /* NOTREACHED */ 188 return (0); 189 } 190 191 /* 192 * Exit: deallocate address space and other resources, change proc state 193 * to zombie, and unlink proc from allproc and parent's lists. Save exit 194 * status and rusage for wait(). Check for child processes and orphan them. 195 * 196 * Must be called with p->p_lock held. Does not return. 197 */ 198 void 199 exit1(struct lwp *l, int exitcode, int signo) 200 { 201 struct proc *p, *child, *next_child, *old_parent, *new_parent; 202 struct pgrp *pgrp; 203 ksiginfo_t ksi; 204 ksiginfoq_t kq; 205 int wakeinit; 206 207 p = l->l_proc; 208 209 KASSERT(mutex_owned(p->p_lock)); 210 KASSERT(p->p_vmspace != NULL); 211 212 if (__predict_false(p == initproc)) { 213 panic("init died (signal %d, exit %d)", signo, exitcode); 214 } 215 216 p->p_sflag |= PS_WEXIT; 217 218 /* 219 * Force all other LWPs to exit before we do. Only then can we 220 * begin to tear down the rest of the process state. 221 */ 222 if (p->p_nlwps > 1) { 223 exit_lwps(l); 224 } 225 226 ksiginfo_queue_init(&kq); 227 228 /* 229 * If we have been asked to stop on exit, do so now. 230 */ 231 if (__predict_false(p->p_sflag & PS_STOPEXIT)) { 232 KERNEL_UNLOCK_ALL(l, &l->l_biglocks); 233 sigclearall(p, &contsigmask, &kq); 234 235 if (!mutex_tryenter(proc_lock)) { 236 mutex_exit(p->p_lock); 237 mutex_enter(proc_lock); 238 mutex_enter(p->p_lock); 239 } 240 p->p_waited = 0; 241 p->p_pptr->p_nstopchild++; 242 p->p_stat = SSTOP; 243 mutex_exit(proc_lock); 244 lwp_lock(l); 245 p->p_nrlwps--; 246 l->l_stat = LSSTOP; 247 lwp_unlock(l); 248 mutex_exit(p->p_lock); 249 lwp_lock(l); 250 mi_switch(l); 251 KERNEL_LOCK(l->l_biglocks, l); 252 mutex_enter(p->p_lock); 253 } 254 255 /* 256 * Bin any remaining signals and mark the process as dying so it will 257 * not be found for, e.g. signals. 258 */ 259 sigfillset(&p->p_sigctx.ps_sigignore); 260 sigclearall(p, NULL, &kq); 261 p->p_stat = SDYING; 262 mutex_exit(p->p_lock); 263 ksiginfo_queue_drain(&kq); 264 265 /* Destroy any lwpctl info. */ 266 if (p->p_lwpctl != NULL) 267 lwp_ctl_exit(); 268 269 /* 270 * Drain all remaining references that procfs, ptrace and others may 271 * have on the process. 272 */ 273 rw_enter(&p->p_reflock, RW_WRITER); 274 275 DPRINTF(("%s: %d.%d exiting.\n", __func__, p->p_pid, l->l_lid)); 276 277 timers_free(p, TIMERS_ALL); 278 #if defined(__HAVE_RAS) 279 ras_purgeall(); 280 #endif 281 282 /* 283 * Close open files, release open-file table and free signal 284 * actions. This may block! 285 */ 286 fd_free(); 287 cwdfree(p->p_cwdi); 288 p->p_cwdi = NULL; 289 doexithooks(p); 290 sigactsfree(p->p_sigacts); 291 292 /* 293 * Write out accounting data. 294 */ 295 (void)acct_process(l); 296 297 #ifdef KTRACE 298 /* 299 * Release trace file. 300 */ 301 if (p->p_tracep != NULL) { 302 mutex_enter(&ktrace_lock); 303 ktrderef(p); 304 mutex_exit(&ktrace_lock); 305 } 306 #endif 307 308 p->p_xexit = exitcode; 309 p->p_xsig = signo; 310 311 /* 312 * If emulation has process exit hook, call it now. 313 * Set the exit status now so that the exit hook has 314 * an opportunity to tweak it (COMPAT_LINUX requires 315 * this for thread group emulation) 316 */ 317 if (p->p_emul->e_proc_exit) 318 (*p->p_emul->e_proc_exit)(p); 319 320 /* 321 * Free the VM resources we're still holding on to. 322 * We must do this from a valid thread because doing 323 * so may block. This frees vmspace, which we don't 324 * need anymore. The only remaining lwp is the one 325 * we run at this moment, nothing runs in userland 326 * anymore. 327 */ 328 uvm_proc_exit(p); 329 330 /* 331 * Stop profiling. 332 */ 333 if (__predict_false((p->p_stflag & PST_PROFIL) != 0)) { 334 mutex_spin_enter(&p->p_stmutex); 335 stopprofclock(p); 336 mutex_spin_exit(&p->p_stmutex); 337 } 338 339 /* 340 * If parent is waiting for us to exit or exec, PL_PPWAIT is set; we 341 * wake up the parent early to avoid deadlock. We can do this once 342 * the VM resources are released. 343 */ 344 mutex_enter(proc_lock); 345 if (p->p_lflag & PL_PPWAIT) { 346 #if 0 347 lwp_t *lp; 348 349 l->l_lwpctl = NULL; /* was on loan from blocked parent */ 350 p->p_lflag &= ~PL_PPWAIT; 351 352 lp = p->p_vforklwp; 353 p->p_vforklwp = NULL; 354 lp->l_pflag &= ~LP_VFORKWAIT; /* XXX */ 355 cv_broadcast(&lp->l_waitcv); 356 #else 357 l->l_lwpctl = NULL; /* was on loan from blocked parent */ 358 p->p_lflag &= ~PL_PPWAIT; 359 cv_broadcast(&p->p_pptr->p_waitcv); 360 #endif 361 } 362 363 if (SESS_LEADER(p)) { 364 struct vnode *vprele = NULL, *vprevoke = NULL; 365 struct session *sp = p->p_session; 366 struct tty *tp; 367 368 if (sp->s_ttyvp) { 369 /* 370 * Controlling process. 371 * Signal foreground pgrp, 372 * drain controlling terminal 373 * and revoke access to controlling terminal. 374 */ 375 tp = sp->s_ttyp; 376 mutex_spin_enter(&tty_lock); 377 if (tp->t_session == sp) { 378 /* we can't guarantee the revoke will do this */ 379 pgrp = tp->t_pgrp; 380 tp->t_pgrp = NULL; 381 tp->t_session = NULL; 382 mutex_spin_exit(&tty_lock); 383 if (pgrp != NULL) { 384 pgsignal(pgrp, SIGHUP, 1); 385 } 386 mutex_exit(proc_lock); 387 (void) ttywait(tp); 388 mutex_enter(proc_lock); 389 390 /* The tty could have been revoked. */ 391 vprevoke = sp->s_ttyvp; 392 } else 393 mutex_spin_exit(&tty_lock); 394 vprele = sp->s_ttyvp; 395 sp->s_ttyvp = NULL; 396 /* 397 * s_ttyp is not zero'd; we use this to indicate 398 * that the session once had a controlling terminal. 399 * (for logging and informational purposes) 400 */ 401 } 402 sp->s_leader = NULL; 403 404 if (vprevoke != NULL || vprele != NULL) { 405 if (vprevoke != NULL) { 406 /* Releases proc_lock. */ 407 proc_sessrele(sp); 408 VOP_REVOKE(vprevoke, REVOKEALL); 409 } else 410 mutex_exit(proc_lock); 411 if (vprele != NULL) 412 vrele(vprele); 413 mutex_enter(proc_lock); 414 } 415 } 416 fixjobc(p, p->p_pgrp, 0); 417 418 /* 419 * Finalize the last LWP's specificdata, as well as the 420 * specificdata for the proc itself. 421 */ 422 lwp_finispecific(l); 423 proc_finispecific(p); 424 425 /* 426 * Notify interested parties of our demise. 427 */ 428 KNOTE(&p->p_klist, NOTE_EXIT); 429 430 SDT_PROBE(proc, kernel, , exit, 431 ((p->p_sflag & PS_COREDUMP) ? CLD_DUMPED : 432 (p->p_xsig ? CLD_KILLED : CLD_EXITED)), 433 0,0,0,0); 434 435 #if PERFCTRS 436 /* 437 * Save final PMC information in parent process & clean up. 438 */ 439 if (PMC_ENABLED(p)) { 440 pmc_save_context(p); 441 pmc_accumulate(p->p_pptr, p); 442 pmc_process_exit(p); 443 } 444 #endif 445 446 /* 447 * Reset p_opptr pointer of all former children which got 448 * traced by another process and were reparented. We reset 449 * it to NULL here; the trace detach code then reparents 450 * the child to initproc. We only check allproc list, since 451 * eventual former children on zombproc list won't reference 452 * p_opptr anymore. 453 */ 454 if (__predict_false(p->p_slflag & PSL_CHTRACED)) { 455 struct proc *q; 456 PROCLIST_FOREACH(q, &allproc) { 457 if (q->p_opptr == p) 458 q->p_opptr = NULL; 459 } 460 PROCLIST_FOREACH(q, &zombproc) { 461 if (q->p_opptr == p) 462 q->p_opptr = NULL; 463 } 464 } 465 466 /* 467 * Give orphaned children to init(8). 468 */ 469 child = LIST_FIRST(&p->p_children); 470 wakeinit = (child != NULL); 471 for (; child != NULL; child = next_child) { 472 next_child = LIST_NEXT(child, p_sibling); 473 474 /* 475 * Traced processes are killed since their existence 476 * means someone is screwing up. Since we reset the 477 * trace flags, the logic in sys_wait4() would not be 478 * triggered to reparent the process to its 479 * original parent, so we must do this here. 480 */ 481 if (__predict_false(child->p_slflag & PSL_TRACED)) { 482 mutex_enter(p->p_lock); 483 child->p_slflag &= 484 ~(PSL_TRACED|PSL_FSTRACE|PSL_SYSCALL); 485 mutex_exit(p->p_lock); 486 if (child->p_opptr != child->p_pptr) { 487 struct proc *t = child->p_opptr; 488 proc_reparent(child, t ? t : initproc); 489 child->p_opptr = NULL; 490 } else 491 proc_reparent(child, initproc); 492 killproc(child, "orphaned traced process"); 493 } else 494 proc_reparent(child, initproc); 495 } 496 497 /* 498 * Move proc from allproc to zombproc, it's now nearly ready to be 499 * collected by parent. 500 */ 501 LIST_REMOVE(l, l_list); 502 LIST_REMOVE(p, p_list); 503 LIST_INSERT_HEAD(&zombproc, p, p_list); 504 505 /* 506 * Mark the process as dead. We must do this before we signal 507 * the parent. 508 */ 509 p->p_stat = SDEAD; 510 511 /* Put in front of parent's sibling list for parent to collect it */ 512 old_parent = p->p_pptr; 513 old_parent->p_nstopchild++; 514 if (LIST_FIRST(&old_parent->p_children) != p) { 515 /* Put child where it can be found quickly */ 516 LIST_REMOVE(p, p_sibling); 517 LIST_INSERT_HEAD(&old_parent->p_children, p, p_sibling); 518 } 519 520 /* 521 * Notify parent that we're gone. If parent has the P_NOCLDWAIT 522 * flag set, notify init instead (and hope it will handle 523 * this situation). 524 */ 525 if (old_parent->p_flag & (PK_NOCLDWAIT|PK_CLDSIGIGN)) { 526 proc_reparent(p, initproc); 527 wakeinit = 1; 528 529 /* 530 * If this was the last child of our parent, notify 531 * parent, so in case he was wait(2)ing, he will 532 * continue. 533 */ 534 if (LIST_FIRST(&old_parent->p_children) == NULL) 535 cv_broadcast(&old_parent->p_waitcv); 536 } 537 538 /* Reload parent pointer, since p may have been reparented above */ 539 new_parent = p->p_pptr; 540 541 if (__predict_false((p->p_slflag & PSL_FSTRACE) == 0 && 542 p->p_exitsig != 0)) { 543 exit_psignal(p, new_parent, &ksi); 544 kpsignal(new_parent, &ksi, NULL); 545 } 546 547 /* Calculate the final rusage info. */ 548 calcru(p, &p->p_stats->p_ru.ru_utime, &p->p_stats->p_ru.ru_stime, 549 NULL, NULL); 550 551 if (wakeinit) 552 cv_broadcast(&initproc->p_waitcv); 553 554 callout_destroy(&l->l_timeout_ch); 555 556 /* 557 * Release any PCU resources before becoming a zombie. 558 */ 559 pcu_discard_all(l); 560 561 mutex_enter(p->p_lock); 562 /* Free the linux lwp id */ 563 if ((l->l_pflag & LP_PIDLID) != 0 && l->l_lid != p->p_pid) 564 proc_free_pid(l->l_lid); 565 lwp_drainrefs(l); 566 lwp_lock(l); 567 l->l_prflag &= ~LPR_DETACHED; 568 l->l_stat = LSZOMB; 569 lwp_unlock(l); 570 KASSERT(curlwp == l); 571 KASSERT(p->p_nrlwps == 1); 572 KASSERT(p->p_nlwps == 1); 573 p->p_stat = SZOMB; 574 p->p_nrlwps--; 575 p->p_nzlwps++; 576 p->p_ndlwps = 0; 577 mutex_exit(p->p_lock); 578 579 /* 580 * Signal the parent to collect us, and drop the proclist lock. 581 * Drop debugger/procfs lock; no new references can be gained. 582 */ 583 cv_broadcast(&p->p_pptr->p_waitcv); 584 rw_exit(&p->p_reflock); 585 mutex_exit(proc_lock); 586 587 /* Verify that we hold no locks other than the kernel lock. */ 588 LOCKDEBUG_BARRIER(&kernel_lock, 0); 589 590 /* 591 * NOTE: WE ARE NO LONGER ALLOWED TO SLEEP! 592 */ 593 594 /* 595 * Give machine-dependent code a chance to free any MD LWP 596 * resources. This must be done before uvm_lwp_exit(), in 597 * case these resources are in the PCB. 598 */ 599 cpu_lwp_free(l, 1); 600 601 pmap_deactivate(l); 602 603 /* This process no longer needs to hold the kernel lock. */ 604 #ifdef notyet 605 /* XXXSMP hold in lwp_userret() */ 606 KERNEL_UNLOCK_LAST(l); 607 #else 608 KERNEL_UNLOCK_ALL(l, NULL); 609 #endif 610 611 lwp_exit_switchaway(l); 612 } 613 614 void 615 exit_lwps(struct lwp *l) 616 { 617 proc_t *p = l->l_proc; 618 lwp_t *l2; 619 int nlocks; 620 621 KERNEL_UNLOCK_ALL(l, &nlocks); 622 retry: 623 KASSERT(mutex_owned(p->p_lock)); 624 625 /* 626 * Interrupt LWPs in interruptable sleep, unsuspend suspended 627 * LWPs and then wait for everyone else to finish. 628 */ 629 LIST_FOREACH(l2, &p->p_lwps, l_sibling) { 630 if (l2 == l) 631 continue; 632 lwp_lock(l2); 633 l2->l_flag |= LW_WEXIT; 634 if ((l2->l_stat == LSSLEEP && (l2->l_flag & LW_SINTR)) || 635 l2->l_stat == LSSUSPENDED || l2->l_stat == LSSTOP) { 636 /* setrunnable() will release the lock. */ 637 setrunnable(l2); 638 continue; 639 } 640 lwp_unlock(l2); 641 } 642 643 /* 644 * Wait for every LWP to exit. Note: LWPs can get suspended/slept 645 * behind us or there may even be new LWPs created. Therefore, a 646 * full retry is required on error. 647 */ 648 while (p->p_nlwps > 1) { 649 if (lwp_wait(l, 0, NULL, true)) { 650 goto retry; 651 } 652 } 653 654 KERNEL_LOCK(nlocks, l); 655 KASSERT(p->p_nlwps == 1); 656 } 657 658 int 659 do_sys_waitid(idtype_t idtype, id_t id, int *pid, int *status, int options, 660 struct wrusage *wru, siginfo_t *si) 661 { 662 proc_t *child; 663 int error; 664 665 666 if (wru != NULL) 667 memset(wru, 0, sizeof(*wru)); 668 if (si != NULL) 669 memset(si, 0, sizeof(*si)); 670 671 mutex_enter(proc_lock); 672 error = find_stopped_child(curproc, idtype, id, options, &child, 673 wru, si); 674 if (child == NULL) { 675 mutex_exit(proc_lock); 676 *pid = 0; 677 return error; 678 } 679 *pid = child->p_pid; 680 681 if (child->p_stat == SZOMB) { 682 /* Child is exiting */ 683 *status = P_WAITSTATUS(child); 684 /* proc_free() will release the proc_lock. */ 685 if (options & WNOWAIT) { 686 mutex_exit(proc_lock); 687 } else { 688 proc_free(child, wru); 689 } 690 } else { 691 /* Don't mark SIGCONT if we are being stopped */ 692 *status = (child->p_xsig == SIGCONT && child->p_stat != SSTOP) ? 693 W_CONTCODE() : W_STOPCODE(child->p_xsig); 694 mutex_exit(proc_lock); 695 } 696 return 0; 697 } 698 699 int 700 do_sys_wait(int *pid, int *status, int options, struct rusage *ru) 701 { 702 idtype_t idtype; 703 id_t id; 704 int ret; 705 struct wrusage wru; 706 707 /* 708 * Translate the special pid values into the (idtype, pid) 709 * pair for wait6. The WAIT_MYPGRP case is handled by 710 * find_stopped_child() on its own. 711 */ 712 if (*pid == WAIT_ANY) { 713 idtype = P_ALL; 714 id = 0; 715 } else if (*pid < 0) { 716 idtype = P_PGID; 717 id = (id_t)-*pid; 718 } else { 719 idtype = P_PID; 720 id = (id_t)*pid; 721 } 722 options |= WEXITED | WTRAPPED; 723 ret = do_sys_waitid(idtype, id, pid, status, options, ru ? &wru : NULL, 724 NULL); 725 if (ru) 726 *ru = wru.wru_self; 727 return ret; 728 } 729 730 int 731 sys___wait450(struct lwp *l, const struct sys___wait450_args *uap, 732 register_t *retval) 733 { 734 /* { 735 syscallarg(int) pid; 736 syscallarg(int *) status; 737 syscallarg(int) options; 738 syscallarg(struct rusage *) rusage; 739 } */ 740 int error, status, pid = SCARG(uap, pid); 741 struct rusage ru; 742 743 error = do_sys_wait(&pid, &status, SCARG(uap, options), 744 SCARG(uap, rusage) != NULL ? &ru : NULL); 745 746 retval[0] = pid; 747 if (pid == 0) { 748 return error; 749 } 750 if (SCARG(uap, status)) { 751 error = copyout(&status, SCARG(uap, status), sizeof(status)); 752 } 753 if (SCARG(uap, rusage) && error == 0) { 754 error = copyout(&ru, SCARG(uap, rusage), sizeof(ru)); 755 } 756 return error; 757 } 758 759 int 760 sys_wait6(struct lwp *l, const struct sys_wait6_args *uap, register_t *retval) 761 { 762 /* { 763 syscallarg(idtype_t) idtype; 764 syscallarg(id_t) id; 765 syscallarg(int *) status; 766 syscallarg(int) options; 767 syscallarg(struct wrusage *) wru; 768 syscallarg(siginfo_t *) si; 769 } */ 770 struct wrusage wru, *wrup; 771 siginfo_t si, *sip; 772 idtype_t idtype; 773 int pid; 774 id_t id; 775 int error, status; 776 777 idtype = SCARG(uap, idtype); 778 id = SCARG(uap, id); 779 780 if (SCARG(uap, wru) != NULL) 781 wrup = &wru; 782 else 783 wrup = NULL; 784 785 if (SCARG(uap, info) != NULL) 786 sip = &si; 787 else 788 sip = NULL; 789 790 /* 791 * We expect all callers of wait6() to know about WEXITED and 792 * WTRAPPED. 793 */ 794 error = do_sys_waitid(idtype, id, &pid, &status, SCARG(uap, options), 795 wrup, sip); 796 797 retval[0] = pid; /* tell userland who it was */ 798 799 #if 0 800 /* 801 * should we copyout if there was no process, hence no useful data? 802 * We don't for an old sytle wait4() (etc) but I believe 803 * FreeBSD does for wait6(), so a tossup... Go with FreeBSD for now. 804 */ 805 if (pid == 0) 806 return error; 807 #endif 808 809 if (SCARG(uap, status) != NULL && error == 0) 810 error = copyout(&status, SCARG(uap, status), sizeof(status)); 811 if (SCARG(uap, wru) != NULL && error == 0) 812 error = copyout(&wru, SCARG(uap, wru), sizeof(wru)); 813 if (SCARG(uap, info) != NULL && error == 0) 814 error = copyout(&si, SCARG(uap, info), sizeof(si)); 815 return error; 816 } 817 818 819 /* 820 * Find a process that matches the provided criteria, and fill siginfo 821 * and resources if found. 822 * Returns: 823 * -1: Not found, abort early 824 * 0: Not matched 825 * 1: Matched, there might be more matches 826 * 2: This is the only match 827 */ 828 static int 829 match_process(const struct proc *pp, struct proc **q, idtype_t idtype, id_t id, 830 int options, struct wrusage *wrusage, siginfo_t *siginfo) 831 { 832 struct rusage *rup; 833 struct proc *p = *q; 834 int rv = 1; 835 836 mutex_enter(p->p_lock); 837 switch (idtype) { 838 case P_ALL: 839 break; 840 case P_PID: 841 if (p->p_pid != (pid_t)id) { 842 mutex_exit(p->p_lock); 843 p = *q = proc_find_raw((pid_t)id); 844 if (p == NULL || p->p_stat == SIDL || p->p_pptr != pp) { 845 *q = NULL; 846 return -1; 847 } 848 mutex_enter(p->p_lock); 849 } 850 rv++; 851 break; 852 case P_PGID: 853 if (p->p_pgid != (pid_t)id) 854 goto out; 855 break; 856 case P_SID: 857 if (p->p_session->s_sid != (pid_t)id) 858 goto out; 859 break; 860 case P_UID: 861 if (kauth_cred_geteuid(p->p_cred) != (uid_t)id) 862 goto out; 863 break; 864 case P_GID: 865 if (kauth_cred_getegid(p->p_cred) != (gid_t)id) 866 goto out; 867 break; 868 case P_CID: 869 case P_PSETID: 870 case P_CPUID: 871 /* XXX: Implement me */ 872 default: 873 out: 874 mutex_exit(p->p_lock); 875 return 0; 876 } 877 878 if ((options & WEXITED) == 0 && p->p_stat == SZOMB) 879 goto out; 880 881 if (siginfo != NULL) { 882 siginfo->si_errno = 0; 883 884 /* 885 * SUSv4 requires that the si_signo value is always 886 * SIGCHLD. Obey it despite the rfork(2) interface 887 * allows to request other signal for child exit 888 * notification. 889 */ 890 siginfo->si_signo = SIGCHLD; 891 892 /* 893 * This is still a rough estimate. We will fix the 894 * cases TRAPPED, STOPPED, and CONTINUED later. 895 */ 896 if (p->p_sflag & PS_COREDUMP) { 897 siginfo->si_code = CLD_DUMPED; 898 siginfo->si_status = p->p_xsig; 899 } else if (p->p_xsig) { 900 siginfo->si_code = CLD_KILLED; 901 siginfo->si_status = p->p_xsig; 902 } else { 903 siginfo->si_code = CLD_EXITED; 904 siginfo->si_status = p->p_xexit; 905 } 906 907 siginfo->si_pid = p->p_pid; 908 siginfo->si_uid = kauth_cred_geteuid(p->p_cred); 909 siginfo->si_utime = p->p_stats->p_ru.ru_utime.tv_sec; 910 siginfo->si_stime = p->p_stats->p_ru.ru_stime.tv_sec; 911 } 912 913 /* 914 * There should be no reason to limit resources usage info to 915 * exited processes only. A snapshot about any resources used 916 * by a stopped process may be exactly what is needed. 917 */ 918 if (wrusage != NULL) { 919 rup = &wrusage->wru_self; 920 *rup = p->p_stats->p_ru; 921 calcru(p, &rup->ru_utime, &rup->ru_stime, NULL, NULL); 922 923 rup = &wrusage->wru_children; 924 *rup = p->p_stats->p_cru; 925 calcru(p, &rup->ru_utime, &rup->ru_stime, NULL, NULL); 926 } 927 928 mutex_exit(p->p_lock); 929 return rv; 930 } 931 932 /* 933 * Determine if there are existing processes being debugged 934 * that used to be (and sometime later will be again) children 935 * of a specific parent (while matching wait criteria) 936 */ 937 static bool 938 debugged_child_exists(idtype_t idtype, id_t id, int options, siginfo_t *si, 939 const struct proc *parent) 940 { 941 struct proc *pp; 942 943 /* 944 * If we are searching for a specific pid, we can optimise a little 945 */ 946 if (idtype == P_PID) { 947 /* 948 * Check the specific process to see if its real parent is us 949 */ 950 pp = proc_find_raw((pid_t)id); 951 if (pp != NULL && pp->p_stat != SIDL && pp->p_opptr == parent) { 952 /* 953 * using P_ALL here avoids match_process() doing the 954 * same work that we just did, but incorrectly for 955 * this scenario. 956 */ 957 if (match_process(parent, &pp, P_ALL, id, options, 958 NULL, si)) 959 return true; 960 } 961 return false; 962 } 963 964 /* 965 * For the hard cases, just look everywhere to see if some 966 * stolen (reparented) process is really our lost child. 967 * Then check if that process could satisfy the wait conditions. 968 */ 969 970 /* 971 * XXX inefficient, but hopefully fairly rare. 972 * XXX should really use a list of reparented processes. 973 */ 974 PROCLIST_FOREACH(pp, &allproc) { 975 if (pp->p_stat == SIDL) /* XXX impossible ?? */ 976 continue; 977 if (pp->p_opptr == parent && 978 match_process(parent, &pp, idtype, id, options, NULL, si)) 979 return true; 980 } 981 PROCLIST_FOREACH(pp, &zombproc) { 982 if (pp->p_stat == SIDL) /* XXX impossible ?? */ 983 continue; 984 if (pp->p_opptr == parent && 985 match_process(parent, &pp, idtype, id, options, NULL, si)) 986 return true; 987 } 988 989 return false; 990 } 991 992 /* 993 * Scan list of child processes for a child process that has stopped or 994 * exited. Used by sys_wait4 and 'compat' equivalents. 995 * 996 * Must be called with the proc_lock held, and may release while waiting. 997 */ 998 static int 999 find_stopped_child(struct proc *parent, idtype_t idtype, id_t id, int options, 1000 struct proc **child_p, struct wrusage *wru, siginfo_t *si) 1001 { 1002 struct proc *child, *dead; 1003 int error; 1004 1005 KASSERT(mutex_owned(proc_lock)); 1006 1007 if (options & ~WALLOPTS) { 1008 *child_p = NULL; 1009 return EINVAL; 1010 } 1011 1012 if ((options & WSELECTOPTS) == 0) { 1013 /* 1014 * We will be unable to find any matching processes, 1015 * because there are no known events to look for. 1016 * Prefer to return error instead of blocking 1017 * indefinitely. 1018 */ 1019 *child_p = NULL; 1020 return EINVAL; 1021 } 1022 1023 if ((pid_t)id == WAIT_MYPGRP && (idtype == P_PID || idtype == P_PGID)) { 1024 mutex_enter(parent->p_lock); 1025 id = (id_t)parent->p_pgid; 1026 mutex_exit(parent->p_lock); 1027 idtype = P_PGID; 1028 } 1029 1030 for (;;) { 1031 error = ECHILD; 1032 dead = NULL; 1033 1034 LIST_FOREACH(child, &parent->p_children, p_sibling) { 1035 int rv = match_process(parent, &child, idtype, id, 1036 options, wru, si); 1037 if (rv == -1) 1038 break; 1039 if (rv == 0) 1040 continue; 1041 1042 /* 1043 * Wait for processes with p_exitsig != SIGCHLD 1044 * processes only if WALTSIG is set; wait for 1045 * processes with p_exitsig == SIGCHLD only 1046 * if WALTSIG is clear. 1047 */ 1048 if (((options & WALLSIG) == 0) && 1049 (options & WALTSIG ? child->p_exitsig == SIGCHLD 1050 : P_EXITSIG(child) != SIGCHLD)){ 1051 if (rv == 2) { 1052 child = NULL; 1053 break; 1054 } 1055 continue; 1056 } 1057 1058 error = 0; 1059 if ((options & WNOZOMBIE) == 0) { 1060 if (child->p_stat == SZOMB) 1061 break; 1062 if (child->p_stat == SDEAD) { 1063 /* 1064 * We may occasionally arrive here 1065 * after receiving a signal, but 1066 * immediately before the child 1067 * process is zombified. The wait 1068 * will be short, so avoid returning 1069 * to userspace. 1070 */ 1071 dead = child; 1072 } 1073 } 1074 1075 if ((options & WCONTINUED) != 0 && 1076 child->p_xsig == SIGCONT && 1077 (child->p_sflag & PS_CONTINUED)) { 1078 if ((options & WNOWAIT) == 0) { 1079 child->p_sflag &= ~PS_CONTINUED; 1080 child->p_waited = 1; 1081 parent->p_nstopchild--; 1082 } 1083 if (si) { 1084 si->si_status = child->p_xsig; 1085 si->si_code = CLD_CONTINUED; 1086 } 1087 break; 1088 } 1089 1090 if ((options & (WTRAPPED|WSTOPPED)) != 0 && 1091 child->p_stat == SSTOP && 1092 child->p_waited == 0 && 1093 ((child->p_slflag & PSL_TRACED) || 1094 options & (WUNTRACED|WSTOPPED))) { 1095 if ((options & WNOWAIT) == 0) { 1096 child->p_waited = 1; 1097 parent->p_nstopchild--; 1098 } 1099 if (si) { 1100 si->si_status = child->p_xsig; 1101 si->si_code = 1102 (child->p_slflag & PSL_TRACED) ? 1103 CLD_TRAPPED : CLD_STOPPED; 1104 } 1105 break; 1106 } 1107 if (parent->p_nstopchild == 0 || rv == 2) { 1108 child = NULL; 1109 break; 1110 } 1111 } 1112 1113 /* 1114 * If we found nothing, but we are the bereaved parent 1115 * of a stolen child, look and see if that child (or 1116 * one of them) meets our search criteria. If so, then 1117 * we cannot succeed, but we can hang (wait...), 1118 * or if WNOHANG, return 0 instead of ECHILD 1119 */ 1120 if (child == NULL && error == ECHILD && 1121 (parent->p_slflag & PSL_CHTRACED) && 1122 debugged_child_exists(idtype, id, options, si, parent)) 1123 error = 0; 1124 1125 if (child != NULL || error != 0 || 1126 ((options & WNOHANG) != 0 && dead == NULL)) { 1127 *child_p = child; 1128 return error; 1129 } 1130 1131 /* 1132 * Wait for another child process to stop. 1133 */ 1134 error = cv_wait_sig(&parent->p_waitcv, proc_lock); 1135 1136 if (error != 0) { 1137 *child_p = NULL; 1138 return error; 1139 } 1140 } 1141 } 1142 1143 /* 1144 * Free a process after parent has taken all the state info. Must be called 1145 * with the proclist lock held, and will release before returning. 1146 * 1147 * *ru is returned to the caller, and must be freed by the caller. 1148 */ 1149 static void 1150 proc_free(struct proc *p, struct wrusage *wru) 1151 { 1152 struct proc *parent = p->p_pptr; 1153 struct lwp *l; 1154 ksiginfo_t ksi; 1155 kauth_cred_t cred1, cred2; 1156 uid_t uid; 1157 1158 KASSERT(mutex_owned(proc_lock)); 1159 KASSERT(p->p_nlwps == 1); 1160 KASSERT(p->p_nzlwps == 1); 1161 KASSERT(p->p_nrlwps == 0); 1162 KASSERT(p->p_stat == SZOMB); 1163 1164 /* 1165 * If we got the child via ptrace(2) or procfs, and 1166 * the parent is different (meaning the process was 1167 * attached, rather than run as a child), then we need 1168 * to give it back to the old parent, and send the 1169 * parent the exit signal. The rest of the cleanup 1170 * will be done when the old parent waits on the child. 1171 */ 1172 if ((p->p_slflag & PSL_TRACED) != 0 && p->p_opptr != parent) { 1173 mutex_enter(p->p_lock); 1174 p->p_slflag &= ~(PSL_TRACED|PSL_FSTRACE|PSL_SYSCALL); 1175 mutex_exit(p->p_lock); 1176 parent = (p->p_opptr == NULL) ? initproc : p->p_opptr; 1177 proc_reparent(p, parent); 1178 p->p_opptr = NULL; 1179 if (p->p_exitsig != 0) { 1180 exit_psignal(p, parent, &ksi); 1181 kpsignal(parent, &ksi, NULL); 1182 } 1183 cv_broadcast(&parent->p_waitcv); 1184 mutex_exit(proc_lock); 1185 return; 1186 } 1187 1188 sched_proc_exit(parent, p); 1189 1190 /* 1191 * Add child times of exiting process onto its own times. 1192 * This cannot be done any earlier else it might get done twice. 1193 */ 1194 l = LIST_FIRST(&p->p_lwps); 1195 p->p_stats->p_ru.ru_nvcsw += (l->l_ncsw - l->l_nivcsw); 1196 p->p_stats->p_ru.ru_nivcsw += l->l_nivcsw; 1197 ruadd(&p->p_stats->p_ru, &l->l_ru); 1198 ruadd(&p->p_stats->p_ru, &p->p_stats->p_cru); 1199 ruadd(&parent->p_stats->p_cru, &p->p_stats->p_ru); 1200 if (wru != NULL) { 1201 wru->wru_self = p->p_stats->p_ru; 1202 wru->wru_children = p->p_stats->p_cru; 1203 } 1204 p->p_xsig = 0; 1205 p->p_xexit = 0; 1206 1207 /* 1208 * At this point we are going to start freeing the final resources. 1209 * If anyone tries to access the proc structure after here they will 1210 * get a shock - bits are missing. Attempt to make it hard! We 1211 * don't bother with any further locking past this point. 1212 */ 1213 p->p_stat = SIDL; /* not even a zombie any more */ 1214 LIST_REMOVE(p, p_list); /* off zombproc */ 1215 parent->p_nstopchild--; 1216 LIST_REMOVE(p, p_sibling); 1217 1218 /* 1219 * Let pid be reallocated. 1220 */ 1221 proc_free_pid(p->p_pid); 1222 1223 /* 1224 * Unlink process from its process group. 1225 * Releases the proc_lock. 1226 */ 1227 proc_leavepgrp(p); 1228 1229 /* 1230 * Delay release until after lwp_free. 1231 */ 1232 cred2 = l->l_cred; 1233 1234 /* 1235 * Free the last LWP's resources. 1236 * 1237 * lwp_free ensures the LWP is no longer running on another CPU. 1238 */ 1239 lwp_free(l, false, true); 1240 1241 /* 1242 * Now no one except us can reach the process p. 1243 */ 1244 1245 /* 1246 * Decrement the count of procs running with this uid. 1247 */ 1248 cred1 = p->p_cred; 1249 uid = kauth_cred_getuid(cred1); 1250 (void)chgproccnt(uid, -1); 1251 1252 /* 1253 * Release substructures. 1254 */ 1255 1256 lim_free(p->p_limit); 1257 pstatsfree(p->p_stats); 1258 kauth_cred_free(cred1); 1259 kauth_cred_free(cred2); 1260 1261 /* 1262 * Release reference to text vnode 1263 */ 1264 if (p->p_textvp) 1265 vrele(p->p_textvp); 1266 1267 mutex_destroy(&p->p_auxlock); 1268 mutex_obj_free(p->p_lock); 1269 mutex_destroy(&p->p_stmutex); 1270 cv_destroy(&p->p_waitcv); 1271 cv_destroy(&p->p_lwpcv); 1272 rw_destroy(&p->p_reflock); 1273 1274 proc_free_mem(p); 1275 } 1276 1277 /* 1278 * Change the parent of a process for tracing purposes. 1279 */ 1280 void 1281 proc_changeparent(struct proc *t, struct proc *p) 1282 { 1283 SET(t->p_slflag, PSL_TRACED); 1284 t->p_opptr = t->p_pptr; 1285 if (t->p_pptr == p) 1286 return; 1287 struct proc *parent = t->p_pptr; 1288 1289 if (parent->p_lock < t->p_lock) { 1290 if (!mutex_tryenter(parent->p_lock)) { 1291 mutex_exit(t->p_lock); 1292 mutex_enter(parent->p_lock); 1293 mutex_enter(t->p_lock); 1294 } 1295 } else if (parent->p_lock > t->p_lock) { 1296 mutex_enter(parent->p_lock); 1297 } 1298 parent->p_slflag |= PSL_CHTRACED; 1299 proc_reparent(t, p); 1300 if (parent->p_lock != t->p_lock) 1301 mutex_exit(parent->p_lock); 1302 } 1303 1304 /* 1305 * make process 'parent' the new parent of process 'child'. 1306 * 1307 * Must be called with proc_lock held. 1308 */ 1309 void 1310 proc_reparent(struct proc *child, struct proc *parent) 1311 { 1312 1313 KASSERT(mutex_owned(proc_lock)); 1314 1315 if (child->p_pptr == parent) 1316 return; 1317 1318 if (child->p_stat == SZOMB || child->p_stat == SDEAD || 1319 (child->p_stat == SSTOP && !child->p_waited)) { 1320 child->p_pptr->p_nstopchild--; 1321 parent->p_nstopchild++; 1322 } 1323 if (parent == initproc) { 1324 child->p_exitsig = SIGCHLD; 1325 child->p_ppid = parent->p_pid; 1326 } 1327 1328 LIST_REMOVE(child, p_sibling); 1329 LIST_INSERT_HEAD(&parent->p_children, child, p_sibling); 1330 child->p_pptr = parent; 1331 } 1332