1 /* $NetBSD: kern_exit.c,v 1.298 2023/10/08 12:38:58 ad Exp $ */ 2 3 /*- 4 * Copyright (c) 1998, 1999, 2006, 2007, 2008, 2020, 2023 5 * The NetBSD Foundation, Inc. 6 * All rights reserved. 7 * 8 * This code is derived from software contributed to The NetBSD Foundation 9 * by Jason R. Thorpe of the Numerical Aerospace Simulation Facility, 10 * NASA Ames Research Center, and by Andrew Doran. 11 * 12 * Redistribution and use in source and binary forms, with or without 13 * modification, are permitted provided that the following conditions 14 * are met: 15 * 1. Redistributions of source code must retain the above copyright 16 * notice, this list of conditions and the following disclaimer. 17 * 2. Redistributions in binary form must reproduce the above copyright 18 * notice, this list of conditions and the following disclaimer in the 19 * documentation and/or other materials provided with the distribution. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 22 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 23 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 24 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 25 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 26 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 27 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 28 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 29 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 30 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 31 * POSSIBILITY OF SUCH DAMAGE. 32 */ 33 34 /* 35 * Copyright (c) 1982, 1986, 1989, 1991, 1993 36 * The Regents of the University of California. All rights reserved. 37 * (c) UNIX System Laboratories, Inc. 38 * All or some portions of this file are derived from material licensed 39 * to the University of California by American Telephone and Telegraph 40 * Co. or Unix System Laboratories, Inc. and are reproduced herein with 41 * the permission of UNIX System Laboratories, Inc. 42 * 43 * Redistribution and use in source and binary forms, with or without 44 * modification, are permitted provided that the following conditions 45 * are met: 46 * 1. Redistributions of source code must retain the above copyright 47 * notice, this list of conditions and the following disclaimer. 48 * 2. Redistributions in binary form must reproduce the above copyright 49 * notice, this list of conditions and the following disclaimer in the 50 * documentation and/or other materials provided with the distribution. 51 * 3. Neither the name of the University nor the names of its contributors 52 * may be used to endorse or promote products derived from this software 53 * without specific prior written permission. 54 * 55 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 56 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 57 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 58 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 59 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 60 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 61 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 62 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 63 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 64 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 65 * SUCH DAMAGE. 66 * 67 * @(#)kern_exit.c 8.10 (Berkeley) 2/23/95 68 */ 69 70 #include <sys/cdefs.h> 71 __KERNEL_RCSID(0, "$NetBSD: kern_exit.c,v 1.298 2023/10/08 12:38:58 ad Exp $"); 72 73 #include "opt_ktrace.h" 74 #include "opt_dtrace.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/fstrans.h> 89 #include <sys/vnode.h> 90 #include <sys/syslog.h> 91 #include <sys/pool.h> 92 #include <sys/uidinfo.h> 93 #include <sys/ptrace.h> 94 #include <sys/acct.h> 95 #include <sys/filedesc.h> 96 #include <sys/ras.h> 97 #include <sys/signalvar.h> 98 #include <sys/sched.h> 99 #include <sys/mount.h> 100 #include <sys/syscallargs.h> 101 #include <sys/kauth.h> 102 #include <sys/sleepq.h> 103 #include <sys/lock.h> 104 #include <sys/lockdebug.h> 105 #include <sys/ktrace.h> 106 #include <sys/cpu.h> 107 #include <sys/lwpctl.h> 108 #include <sys/atomic.h> 109 #include <sys/sdt.h> 110 #include <sys/psref.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 /* Verify that we hold no locks other than p->p_lock. */ 210 LOCKDEBUG_BARRIER(p->p_lock, 0); 211 212 /* XXX Temporary: something is leaking kernel_lock. */ 213 KERNEL_UNLOCK_ALL(l, NULL); 214 215 KASSERT(mutex_owned(p->p_lock)); 216 KASSERT(p->p_vmspace != NULL); 217 218 if (__predict_false(p == initproc)) { 219 panic("init died (signal %d, exit %d)", signo, exitcode); 220 } 221 222 p->p_sflag |= PS_WEXIT; 223 224 /* 225 * Force all other LWPs to exit before we do. Only then can we 226 * begin to tear down the rest of the process state. 227 */ 228 if (p->p_nlwps > 1) { 229 exit_lwps(l); 230 } 231 232 ksiginfo_queue_init(&kq); 233 234 /* 235 * If we have been asked to stop on exit, do so now. 236 */ 237 if (__predict_false(p->p_sflag & PS_STOPEXIT)) { 238 KASSERT(l->l_blcnt == 0); 239 sigclearall(p, &contsigmask, &kq); 240 241 if (!mutex_tryenter(&proc_lock)) { 242 mutex_exit(p->p_lock); 243 mutex_enter(&proc_lock); 244 mutex_enter(p->p_lock); 245 } 246 p->p_waited = 0; 247 p->p_pptr->p_nstopchild++; 248 p->p_stat = SSTOP; 249 mutex_exit(&proc_lock); 250 lwp_lock(l); 251 p->p_nrlwps--; 252 l->l_stat = LSSTOP; 253 lwp_unlock(l); 254 mutex_exit(p->p_lock); 255 lwp_lock(l); 256 spc_lock(l->l_cpu); 257 mi_switch(l); 258 mutex_enter(p->p_lock); 259 } 260 261 /* 262 * Bin any remaining signals and mark the process as dying so it will 263 * not be found for, e.g. signals. 264 */ 265 sigfillset(&p->p_sigctx.ps_sigignore); 266 sigclearall(p, NULL, &kq); 267 p->p_stat = SDYING; 268 269 /* 270 * Perform any required thread cleanup. Do this early so 271 * anyone wanting to look us up by our global thread ID 272 * will fail to find us. 273 * 274 * N.B. this will unlock p->p_lock on our behalf. 275 */ 276 lwp_thread_cleanup(l); 277 278 ksiginfo_queue_drain(&kq); 279 280 /* Destroy any lwpctl info. */ 281 if (p->p_lwpctl != NULL) 282 lwp_ctl_exit(); 283 284 /* 285 * Drain all remaining references that procfs, ptrace and others may 286 * have on the process. 287 */ 288 rw_enter(&p->p_reflock, RW_WRITER); 289 290 DPRINTF(("%s: %d.%d exiting.\n", __func__, p->p_pid, l->l_lid)); 291 292 ptimers_free(p, TIMERS_ALL); 293 #if defined(__HAVE_RAS) 294 ras_purgeall(); 295 #endif 296 297 /* 298 * Close open files, release open-file table and free signal 299 * actions. This may block! 300 */ 301 fd_free(); 302 cwdfree(p->p_cwdi); 303 p->p_cwdi = NULL; 304 doexithooks(p); 305 sigactsfree(p->p_sigacts); 306 307 /* 308 * Write out accounting data. 309 */ 310 (void)acct_process(l); 311 312 #ifdef KTRACE 313 /* 314 * Release trace file. 315 */ 316 if (p->p_tracep != NULL) { 317 mutex_enter(&ktrace_lock); 318 ktrderef(p); 319 mutex_exit(&ktrace_lock); 320 } 321 #endif 322 323 p->p_xexit = exitcode; 324 p->p_xsig = signo; 325 326 /* 327 * If emulation has process exit hook, call it now. 328 * Set the exit status now so that the exit hook has 329 * an opportunity to tweak it (COMPAT_LINUX requires 330 * this for thread group emulation) 331 */ 332 if (p->p_emul->e_proc_exit) 333 (*p->p_emul->e_proc_exit)(p); 334 335 /* 336 * Free the VM resources we're still holding on to. 337 * We must do this from a valid thread because doing 338 * so may block. This frees vmspace, which we don't 339 * need anymore. The only remaining lwp is the one 340 * we run at this moment, nothing runs in userland 341 * anymore. 342 */ 343 ruspace(p); /* Update our vm resource use */ 344 uvm_proc_exit(p); 345 346 /* 347 * Stop profiling. 348 */ 349 if (__predict_false((p->p_stflag & PST_PROFIL) != 0)) { 350 mutex_spin_enter(&p->p_stmutex); 351 stopprofclock(p); 352 mutex_spin_exit(&p->p_stmutex); 353 } 354 355 /* 356 * If parent is waiting for us to exit or exec, PL_PPWAIT is set; we 357 * wake up the parent early to avoid deadlock. We can do this once 358 * the VM resources are released. 359 */ 360 mutex_enter(&proc_lock); 361 if (p->p_lflag & PL_PPWAIT) { 362 lwp_t *lp; 363 364 l->l_lwpctl = NULL; /* was on loan from blocked parent */ 365 p->p_lflag &= ~PL_PPWAIT; 366 367 lp = p->p_vforklwp; 368 p->p_vforklwp = NULL; 369 lp->l_vforkwaiting = false; 370 cv_broadcast(&lp->l_waitcv); 371 } 372 373 if (SESS_LEADER(p)) { 374 struct vnode *vprele = NULL, *vprevoke = NULL; 375 struct session *sp = p->p_session; 376 struct tty *tp; 377 378 if (sp->s_ttyvp) { 379 /* 380 * Controlling process. 381 * Signal foreground pgrp, 382 * drain controlling terminal 383 * and revoke access to controlling terminal. 384 */ 385 tp = sp->s_ttyp; 386 mutex_spin_enter(&tty_lock); 387 if (tp->t_session == sp) { 388 /* we can't guarantee the revoke will do this */ 389 pgrp = tp->t_pgrp; 390 tp->t_pgrp = NULL; 391 tp->t_session = NULL; 392 mutex_spin_exit(&tty_lock); 393 if (pgrp != NULL) { 394 pgsignal(pgrp, SIGHUP, 1); 395 } 396 mutex_exit(&proc_lock); 397 (void) ttywait(tp); 398 mutex_enter(&proc_lock); 399 400 /* The tty could have been revoked. */ 401 vprevoke = sp->s_ttyvp; 402 } else 403 mutex_spin_exit(&tty_lock); 404 vprele = sp->s_ttyvp; 405 sp->s_ttyvp = NULL; 406 /* 407 * s_ttyp is not zero'd; we use this to indicate 408 * that the session once had a controlling terminal. 409 * (for logging and informational purposes) 410 */ 411 } 412 sp->s_leader = NULL; 413 414 if (vprevoke != NULL || vprele != NULL) { 415 if (vprevoke != NULL) { 416 /* Releases proc_lock. */ 417 proc_sessrele(sp); 418 VOP_REVOKE(vprevoke, REVOKEALL); 419 } else 420 mutex_exit(&proc_lock); 421 if (vprele != NULL) 422 vrele(vprele); 423 mutex_enter(&proc_lock); 424 } 425 } 426 fixjobc(p, p->p_pgrp, 0); 427 428 /* Release fstrans private data. */ 429 fstrans_lwp_dtor(l); 430 431 /* 432 * Finalize the last LWP's specificdata, as well as the 433 * specificdata for the proc itself. 434 */ 435 lwp_finispecific(l); 436 proc_finispecific(p); 437 438 /* 439 * Reset p_opptr pointer of all former children which got 440 * traced by another process and were reparented. We reset 441 * it to NULL here; the trace detach code then reparents 442 * the child to initproc. We only check allproc list, since 443 * eventual former children on zombproc list won't reference 444 * p_opptr anymore. 445 */ 446 if (__predict_false(p->p_slflag & PSL_CHTRACED)) { 447 struct proc *q; 448 PROCLIST_FOREACH(q, &allproc) { 449 if (q->p_opptr == p) 450 q->p_opptr = NULL; 451 } 452 PROCLIST_FOREACH(q, &zombproc) { 453 if (q->p_opptr == p) 454 q->p_opptr = NULL; 455 } 456 } 457 458 /* 459 * Give orphaned children to init(8). 460 */ 461 child = LIST_FIRST(&p->p_children); 462 wakeinit = (child != NULL); 463 for (; child != NULL; child = next_child) { 464 next_child = LIST_NEXT(child, p_sibling); 465 466 /* 467 * Traced processes are killed since their existence 468 * means someone is screwing up. Since we reset the 469 * trace flags, the logic in sys_wait4() would not be 470 * triggered to reparent the process to its 471 * original parent, so we must do this here. 472 */ 473 if (__predict_false(child->p_slflag & PSL_TRACED)) { 474 mutex_enter(p->p_lock); 475 child->p_slflag &= 476 ~(PSL_TRACED|PSL_SYSCALL); 477 mutex_exit(p->p_lock); 478 if (child->p_opptr != child->p_pptr) { 479 struct proc *t = child->p_opptr; 480 proc_reparent(child, t ? t : initproc); 481 child->p_opptr = NULL; 482 } else 483 proc_reparent(child, initproc); 484 killproc(child, "orphaned traced process"); 485 } else 486 proc_reparent(child, initproc); 487 } 488 489 /* 490 * Move proc from allproc to zombproc, it's now nearly ready to be 491 * collected by parent. 492 */ 493 LIST_REMOVE(l, l_list); 494 LIST_REMOVE(p, p_list); 495 LIST_INSERT_HEAD(&zombproc, p, p_list); 496 497 /* 498 * Mark the process as dead. We must do this before we signal 499 * the parent. 500 */ 501 p->p_stat = SDEAD; 502 503 /* 504 * Let anyone watching this DTrace probe know what we're 505 * on our way out. 506 */ 507 SDT_PROBE(proc, kernel, , exit, 508 ((p->p_sflag & PS_COREDUMP) ? CLD_DUMPED : 509 (p->p_xsig ? CLD_KILLED : CLD_EXITED)), 510 0,0,0,0); 511 512 /* Put in front of parent's sibling list for parent to collect it */ 513 old_parent = p->p_pptr; 514 old_parent->p_nstopchild++; 515 if (LIST_FIRST(&old_parent->p_children) != p) { 516 /* Put child where it can be found quickly */ 517 LIST_REMOVE(p, p_sibling); 518 LIST_INSERT_HEAD(&old_parent->p_children, p, p_sibling); 519 } 520 521 /* 522 * Notify parent that we're gone. If parent has the P_NOCLDWAIT 523 * flag set, notify init instead (and hope it will handle 524 * this situation). 525 */ 526 if (old_parent->p_flag & (PK_NOCLDWAIT|PK_CLDSIGIGN)) { 527 proc_reparent(p, initproc); 528 wakeinit = 1; 529 530 /* 531 * If this was the last child of our parent, notify 532 * parent, so in case he was wait(2)ing, he will 533 * continue. 534 */ 535 if (LIST_FIRST(&old_parent->p_children) == NULL) 536 cv_broadcast(&old_parent->p_waitcv); 537 } 538 539 /* Reload parent pointer, since p may have been reparented above */ 540 new_parent = p->p_pptr; 541 542 if (__predict_false(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 callout_destroy(&l->l_timeout_ch); 552 553 /* 554 * Release any PCU resources before becoming a zombie. 555 */ 556 pcu_discard_all(l); 557 558 /* 559 * Notify other processes tracking us with a knote that 560 * we're exiting. 561 * 562 * N.B. we do this here because the process is now SDEAD, 563 * and thus cannot have any more knotes attached. Also, 564 * knote_proc_exit() expects that p->p_lock is already 565 * held (and will assert so). 566 */ 567 mutex_enter(p->p_lock); 568 if (!SLIST_EMPTY(&p->p_klist)) { 569 knote_proc_exit(p); 570 } 571 572 /* Free the LWP ID */ 573 proc_free_lwpid(p, l->l_lid); 574 lwp_drainrefs(l); 575 lwp_lock(l); 576 l->l_prflag &= ~LPR_DETACHED; 577 l->l_stat = LSZOMB; 578 lwp_unlock(l); 579 KASSERT(curlwp == l); 580 KASSERT(p->p_nrlwps == 1); 581 KASSERT(p->p_nlwps == 1); 582 p->p_stat = SZOMB; 583 p->p_nrlwps--; 584 p->p_nzlwps++; 585 p->p_ndlwps = 0; 586 mutex_exit(p->p_lock); 587 588 /* 589 * Signal the parent to collect us, and drop the proclist lock. 590 * Drop debugger/procfs lock; no new references can be gained. 591 */ 592 rw_exit(&p->p_reflock); 593 cv_broadcast(&p->p_pptr->p_waitcv); 594 mutex_exit(&proc_lock); 595 if (wakeinit) 596 cv_broadcast(&initproc->p_waitcv); 597 598 /* 599 * NOTE: WE ARE NO LONGER ALLOWED TO SLEEP! 600 */ 601 602 /* 603 * Give machine-dependent code a chance to free any MD LWP 604 * resources. This must be done before uvm_lwp_exit(), in 605 * case these resources are in the PCB. 606 */ 607 cpu_lwp_free(l, 1); 608 609 /* Switch away into oblivion. */ 610 lwp_lock(l); 611 spc_lock(l->l_cpu); 612 mi_switch(l); 613 panic("exit1"); 614 } 615 616 void 617 exit_lwps(struct lwp *l) 618 { 619 proc_t *p = l->l_proc; 620 lwp_t *l2; 621 622 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 lwp_need_userret(l2); 635 if ((l2->l_stat == LSSLEEP && (l2->l_flag & LW_SINTR)) || 636 l2->l_stat == LSSUSPENDED || l2->l_stat == LSSTOP) { 637 l2->l_flag &= ~LW_DBGSUSPEND; 638 /* setrunnable() will release the lock. */ 639 setrunnable(l2); 640 continue; 641 } 642 lwp_unlock(l2); 643 } 644 645 /* 646 * Wait for every LWP to exit. Note: LWPs can get suspended/slept 647 * behind us or there may even be new LWPs created. Therefore, a 648 * full retry is required on error. 649 */ 650 while (p->p_nlwps > 1) { 651 if (lwp_wait(l, 0, NULL, true)) { 652 goto retry; 653 } 654 } 655 656 KASSERT(p->p_nlwps == 1); 657 } 658 659 int 660 do_sys_waitid(idtype_t idtype, id_t id, int *pid, int *status, int options, 661 struct wrusage *wru, siginfo_t *si) 662 { 663 proc_t *child; 664 int error; 665 666 667 if (wru != NULL) 668 memset(wru, 0, sizeof(*wru)); 669 if (si != NULL) 670 memset(si, 0, sizeof(*si)); 671 672 mutex_enter(&proc_lock); 673 error = find_stopped_child(curproc, idtype, id, options, &child, 674 wru, si); 675 if (child == NULL) { 676 mutex_exit(&proc_lock); 677 *pid = 0; 678 *status = 0; 679 return error; 680 } 681 *pid = child->p_pid; 682 683 if (child->p_stat == SZOMB) { 684 /* Child is exiting */ 685 *status = P_WAITSTATUS(child); 686 /* proc_free() will release the proc_lock. */ 687 if (options & WNOWAIT) { 688 mutex_exit(&proc_lock); 689 } else { 690 proc_free(child, wru); 691 } 692 } else { 693 /* Don't mark SIGCONT if we are being stopped */ 694 *status = (child->p_xsig == SIGCONT && child->p_stat != SSTOP) ? 695 W_CONTCODE() : W_STOPCODE(child->p_xsig); 696 mutex_exit(&proc_lock); 697 } 698 return 0; 699 } 700 701 int 702 do_sys_wait(int *pid, int *status, int options, struct rusage *ru) 703 { 704 idtype_t idtype; 705 id_t id; 706 int ret; 707 struct wrusage wru; 708 709 /* 710 * Translate the special pid values into the (idtype, pid) 711 * pair for wait6. The WAIT_MYPGRP case is handled by 712 * find_stopped_child() on its own. 713 */ 714 if (*pid == WAIT_ANY) { 715 idtype = P_ALL; 716 id = 0; 717 } else if (*pid < 0) { 718 idtype = P_PGID; 719 id = (id_t)-*pid; 720 } else { 721 idtype = P_PID; 722 id = (id_t)*pid; 723 } 724 options |= WEXITED | WTRAPPED; 725 ret = do_sys_waitid(idtype, id, pid, status, options, ru ? &wru : NULL, 726 NULL); 727 if (ru) 728 *ru = wru.wru_self; 729 return ret; 730 } 731 732 int 733 sys___wait450(struct lwp *l, const struct sys___wait450_args *uap, 734 register_t *retval) 735 { 736 /* { 737 syscallarg(int) pid; 738 syscallarg(int *) status; 739 syscallarg(int) options; 740 syscallarg(struct rusage *) rusage; 741 } */ 742 int error, status, pid = SCARG(uap, pid); 743 struct rusage ru; 744 745 error = do_sys_wait(&pid, &status, SCARG(uap, options), 746 SCARG(uap, rusage) != NULL ? &ru : NULL); 747 748 retval[0] = pid; 749 if (pid == 0) { 750 return error; 751 } 752 if (SCARG(uap, status)) { 753 error = copyout(&status, SCARG(uap, status), sizeof(status)); 754 } 755 if (SCARG(uap, rusage) && error == 0) { 756 error = copyout(&ru, SCARG(uap, rusage), sizeof(ru)); 757 } 758 return error; 759 } 760 761 int 762 sys_wait6(struct lwp *l, const struct sys_wait6_args *uap, register_t *retval) 763 { 764 /* { 765 syscallarg(idtype_t) idtype; 766 syscallarg(id_t) id; 767 syscallarg(int *) status; 768 syscallarg(int) options; 769 syscallarg(struct wrusage *) wru; 770 syscallarg(siginfo_t *) si; 771 } */ 772 struct wrusage wru, *wrup; 773 siginfo_t si, *sip; 774 idtype_t idtype; 775 int pid; 776 id_t id; 777 int error, status; 778 779 idtype = SCARG(uap, idtype); 780 id = SCARG(uap, id); 781 782 if (SCARG(uap, wru) != NULL) 783 wrup = &wru; 784 else 785 wrup = NULL; 786 787 if (SCARG(uap, info) != NULL) 788 sip = &si; 789 else 790 sip = NULL; 791 792 /* 793 * We expect all callers of wait6() to know about WEXITED and 794 * WTRAPPED. 795 */ 796 error = do_sys_waitid(idtype, id, &pid, &status, SCARG(uap, options), 797 wrup, sip); 798 799 retval[0] = pid; /* tell userland who it was */ 800 801 #if 0 802 /* 803 * should we copyout if there was no process, hence no useful data? 804 * We don't for an old style wait4() (etc) but I believe 805 * FreeBSD does for wait6(), so a tossup... Go with FreeBSD for now. 806 */ 807 if (pid == 0) 808 return error; 809 #endif 810 811 if (SCARG(uap, status) != NULL && error == 0) 812 error = copyout(&status, SCARG(uap, status), sizeof(status)); 813 if (SCARG(uap, wru) != NULL && error == 0) 814 error = copyout(&wru, SCARG(uap, wru), sizeof(wru)); 815 if (SCARG(uap, info) != NULL && error == 0) 816 error = copyout(&si, SCARG(uap, info), sizeof(si)); 817 return error; 818 } 819 820 821 /* 822 * Find a process that matches the provided criteria, and fill siginfo 823 * and resources if found. 824 * Returns: 825 * -1: Not found, abort early 826 * 0: Not matched 827 * 1: Matched, there might be more matches 828 * 2: This is the only match 829 */ 830 static int 831 match_process(const struct proc *pp, struct proc **q, idtype_t idtype, id_t id, 832 int options, struct wrusage *wrusage, siginfo_t *siginfo) 833 { 834 struct rusage *rup; 835 struct proc *p = *q; 836 int rv = 1; 837 838 switch (idtype) { 839 case P_ALL: 840 mutex_enter(p->p_lock); 841 break; 842 case P_PID: 843 if (p->p_pid != (pid_t)id) { 844 p = *q = proc_find_raw((pid_t)id); 845 if (p == NULL || p->p_stat == SIDL || p->p_pptr != pp) { 846 *q = NULL; 847 return -1; 848 } 849 } 850 mutex_enter(p->p_lock); 851 rv++; 852 break; 853 case P_PGID: 854 if (p->p_pgid != (pid_t)id) 855 return 0; 856 mutex_enter(p->p_lock); 857 break; 858 case P_SID: 859 if (p->p_session->s_sid != (pid_t)id) 860 return 0; 861 mutex_enter(p->p_lock); 862 break; 863 case P_UID: 864 mutex_enter(p->p_lock); 865 if (kauth_cred_geteuid(p->p_cred) != (uid_t)id) { 866 mutex_exit(p->p_lock); 867 return 0; 868 } 869 break; 870 case P_GID: 871 mutex_enter(p->p_lock); 872 if (kauth_cred_getegid(p->p_cred) != (gid_t)id) { 873 mutex_exit(p->p_lock); 874 return 0; 875 } 876 break; 877 case P_CID: 878 case P_PSETID: 879 case P_CPUID: 880 /* XXX: Implement me */ 881 default: 882 return 0; 883 } 884 885 if ((options & WEXITED) == 0 && p->p_stat == SZOMB) { 886 mutex_exit(p->p_lock); 887 return 0; 888 } 889 890 if (siginfo != NULL) { 891 siginfo->si_errno = 0; 892 893 /* 894 * SUSv4 requires that the si_signo value is always 895 * SIGCHLD. Obey it despite the rfork(2) interface 896 * allows to request other signal for child exit 897 * notification. 898 */ 899 siginfo->si_signo = SIGCHLD; 900 901 /* 902 * This is still a rough estimate. We will fix the 903 * cases TRAPPED, STOPPED, and CONTINUED later. 904 */ 905 if (p->p_sflag & PS_COREDUMP) { 906 siginfo->si_code = CLD_DUMPED; 907 siginfo->si_status = p->p_xsig; 908 } else if (p->p_xsig) { 909 siginfo->si_code = CLD_KILLED; 910 siginfo->si_status = p->p_xsig; 911 } else { 912 siginfo->si_code = CLD_EXITED; 913 siginfo->si_status = p->p_xexit; 914 } 915 916 siginfo->si_pid = p->p_pid; 917 siginfo->si_uid = kauth_cred_geteuid(p->p_cred); 918 siginfo->si_utime = p->p_stats->p_ru.ru_utime.tv_sec; 919 siginfo->si_stime = p->p_stats->p_ru.ru_stime.tv_sec; 920 } 921 922 /* 923 * There should be no reason to limit resources usage info to 924 * exited processes only. A snapshot about any resources used 925 * by a stopped process may be exactly what is needed. 926 */ 927 if (wrusage != NULL) { 928 rup = &wrusage->wru_self; 929 *rup = p->p_stats->p_ru; 930 calcru(p, &rup->ru_utime, &rup->ru_stime, NULL, NULL); 931 932 rup = &wrusage->wru_children; 933 *rup = p->p_stats->p_cru; 934 calcru(p, &rup->ru_utime, &rup->ru_stime, NULL, NULL); 935 } 936 937 mutex_exit(p->p_lock); 938 return rv; 939 } 940 941 /* 942 * Determine if there are existing processes being debugged 943 * that used to be (and sometime later will be again) children 944 * of a specific parent (while matching wait criteria) 945 */ 946 static bool 947 debugged_child_exists(idtype_t idtype, id_t id, int options, siginfo_t *si, 948 const struct proc *parent) 949 { 950 struct proc *pp; 951 952 /* 953 * If we are searching for a specific pid, we can optimise a little 954 */ 955 if (idtype == P_PID) { 956 /* 957 * Check the specific process to see if its real parent is us 958 */ 959 pp = proc_find_raw((pid_t)id); 960 if (pp != NULL && pp->p_stat != SIDL && pp->p_opptr == parent) { 961 /* 962 * using P_ALL here avoids match_process() doing the 963 * same work that we just did, but incorrectly for 964 * this scenario. 965 */ 966 if (match_process(parent, &pp, P_ALL, id, options, 967 NULL, si)) 968 return true; 969 } 970 return false; 971 } 972 973 /* 974 * For the hard cases, just look everywhere to see if some 975 * stolen (reparented) process is really our lost child. 976 * Then check if that process could satisfy the wait conditions. 977 */ 978 979 /* 980 * XXX inefficient, but hopefully fairly rare. 981 * XXX should really use a list of reparented processes. 982 */ 983 PROCLIST_FOREACH(pp, &allproc) { 984 if (pp->p_stat == SIDL) /* XXX impossible ?? */ 985 continue; 986 if (pp->p_opptr == parent && 987 match_process(parent, &pp, idtype, id, options, NULL, si)) 988 return true; 989 } 990 PROCLIST_FOREACH(pp, &zombproc) { 991 if (pp->p_stat == SIDL) /* XXX impossible ?? */ 992 continue; 993 if (pp->p_opptr == parent && 994 match_process(parent, &pp, idtype, id, options, NULL, si)) 995 return true; 996 } 997 998 return false; 999 } 1000 1001 /* 1002 * Scan list of child processes for a child process that has stopped or 1003 * exited. Used by sys_wait4 and 'compat' equivalents. 1004 * 1005 * Must be called with the proc_lock held, and may release while waiting. 1006 */ 1007 static int 1008 find_stopped_child(struct proc *parent, idtype_t idtype, id_t id, int options, 1009 struct proc **child_p, struct wrusage *wru, siginfo_t *si) 1010 { 1011 struct proc *child, *dead; 1012 int error; 1013 1014 KASSERT(mutex_owned(&proc_lock)); 1015 1016 if (options & ~WALLOPTS) { 1017 *child_p = NULL; 1018 return EINVAL; 1019 } 1020 1021 if ((options & WSELECTOPTS) == 0) { 1022 /* 1023 * We will be unable to find any matching processes, 1024 * because there are no known events to look for. 1025 * Prefer to return error instead of blocking 1026 * indefinitely. 1027 */ 1028 *child_p = NULL; 1029 return EINVAL; 1030 } 1031 1032 if ((pid_t)id == WAIT_MYPGRP && (idtype == P_PID || idtype == P_PGID)) { 1033 id = (id_t)parent->p_pgid; 1034 idtype = P_PGID; 1035 } 1036 1037 for (;;) { 1038 error = ECHILD; 1039 dead = NULL; 1040 1041 LIST_FOREACH(child, &parent->p_children, p_sibling) { 1042 int rv = match_process(parent, &child, idtype, id, 1043 options, wru, si); 1044 if (rv == -1) 1045 break; 1046 if (rv == 0) 1047 continue; 1048 1049 /* 1050 * Wait for processes with p_exitsig != SIGCHLD 1051 * processes only if WALTSIG is set; wait for 1052 * processes with p_exitsig == SIGCHLD only 1053 * if WALTSIG is clear. 1054 */ 1055 if (((options & WALLSIG) == 0) && 1056 (options & WALTSIG ? child->p_exitsig == SIGCHLD 1057 : P_EXITSIG(child) != SIGCHLD)){ 1058 if (rv == 2) { 1059 child = NULL; 1060 break; 1061 } 1062 continue; 1063 } 1064 1065 error = 0; 1066 if ((options & WNOZOMBIE) == 0) { 1067 if (child->p_stat == SZOMB) 1068 break; 1069 if (child->p_stat == SDEAD) { 1070 /* 1071 * We may occasionally arrive here 1072 * after receiving a signal, but 1073 * immediately before the child 1074 * process is zombified. The wait 1075 * will be short, so avoid returning 1076 * to userspace. 1077 */ 1078 dead = child; 1079 } 1080 } 1081 1082 if ((options & WCONTINUED) != 0 && 1083 child->p_xsig == SIGCONT && 1084 (child->p_sflag & PS_CONTINUED)) { 1085 if ((options & WNOWAIT) == 0) { 1086 child->p_sflag &= ~PS_CONTINUED; 1087 child->p_waited = 1; 1088 parent->p_nstopchild--; 1089 } 1090 if (si) { 1091 si->si_status = child->p_xsig; 1092 si->si_code = CLD_CONTINUED; 1093 } 1094 break; 1095 } 1096 1097 if ((options & (WTRAPPED|WSTOPPED)) != 0 && 1098 child->p_stat == SSTOP && 1099 child->p_waited == 0 && 1100 ((child->p_slflag & PSL_TRACED) || 1101 options & (WUNTRACED|WSTOPPED))) { 1102 if ((options & WNOWAIT) == 0) { 1103 child->p_waited = 1; 1104 parent->p_nstopchild--; 1105 } 1106 if (si) { 1107 si->si_status = child->p_xsig; 1108 si->si_code = 1109 (child->p_slflag & PSL_TRACED) ? 1110 CLD_TRAPPED : CLD_STOPPED; 1111 } 1112 break; 1113 } 1114 if (parent->p_nstopchild == 0 || rv == 2) { 1115 child = NULL; 1116 break; 1117 } 1118 } 1119 1120 /* 1121 * If we found nothing, but we are the bereaved parent 1122 * of a stolen child, look and see if that child (or 1123 * one of them) meets our search criteria. If so, then 1124 * we cannot succeed, but we can hang (wait...), 1125 * or if WNOHANG, return 0 instead of ECHILD 1126 */ 1127 if (child == NULL && error == ECHILD && 1128 (parent->p_slflag & PSL_CHTRACED) && 1129 debugged_child_exists(idtype, id, options, si, parent)) 1130 error = 0; 1131 1132 if (child != NULL || error != 0 || 1133 ((options & WNOHANG) != 0 && dead == NULL)) { 1134 *child_p = child; 1135 return error; 1136 } 1137 1138 /* 1139 * Wait for another child process to stop. 1140 */ 1141 error = cv_wait_sig(&parent->p_waitcv, &proc_lock); 1142 1143 if (error != 0) { 1144 *child_p = NULL; 1145 return error; 1146 } 1147 } 1148 } 1149 1150 /* 1151 * Free a process after parent has taken all the state info. Must be called 1152 * with the proclist lock held, and will release before returning. 1153 * 1154 * *ru is returned to the caller, and must be freed by the caller. 1155 */ 1156 static void 1157 proc_free(struct proc *p, struct wrusage *wru) 1158 { 1159 struct proc *parent = p->p_pptr; 1160 struct lwp *l; 1161 ksiginfo_t ksi; 1162 kauth_cred_t cred1, cred2; 1163 uid_t uid; 1164 1165 KASSERT(mutex_owned(&proc_lock)); 1166 KASSERT(p->p_nlwps == 1); 1167 KASSERT(p->p_nzlwps == 1); 1168 KASSERT(p->p_nrlwps == 0); 1169 KASSERT(p->p_stat == SZOMB); 1170 1171 /* 1172 * If we got the child via ptrace(2) or procfs, and 1173 * the parent is different (meaning the process was 1174 * attached, rather than run as a child), then we need 1175 * to give it back to the old parent, and send the 1176 * parent the exit signal. The rest of the cleanup 1177 * will be done when the old parent waits on the child. 1178 */ 1179 if ((p->p_slflag & PSL_TRACED) != 0 && p->p_opptr != parent) { 1180 mutex_enter(p->p_lock); 1181 p->p_slflag &= ~(PSL_TRACED|PSL_SYSCALL); 1182 mutex_exit(p->p_lock); 1183 parent = (p->p_opptr == NULL) ? initproc : p->p_opptr; 1184 proc_reparent(p, parent); 1185 p->p_opptr = NULL; 1186 if (p->p_exitsig != 0) { 1187 exit_psignal(p, parent, &ksi); 1188 kpsignal(parent, &ksi, NULL); 1189 } 1190 cv_broadcast(&parent->p_waitcv); 1191 mutex_exit(&proc_lock); 1192 return; 1193 } 1194 1195 sched_proc_exit(parent, p); 1196 1197 /* 1198 * Add child times of exiting process onto its own times. 1199 * This cannot be done any earlier else it might get done twice. 1200 */ 1201 l = LIST_FIRST(&p->p_lwps); 1202 ruadd(&p->p_stats->p_ru, &l->l_ru); 1203 ruadd(&p->p_stats->p_ru, &p->p_stats->p_cru); 1204 ruadd(&parent->p_stats->p_cru, &p->p_stats->p_ru); 1205 if (wru != NULL) { 1206 wru->wru_self = p->p_stats->p_ru; 1207 wru->wru_children = p->p_stats->p_cru; 1208 } 1209 p->p_xsig = 0; 1210 p->p_xexit = 0; 1211 1212 /* 1213 * At this point we are going to start freeing the final resources. 1214 * If anyone tries to access the proc structure after here they will 1215 * get a shock - bits are missing. Attempt to make it hard! We 1216 * don't bother with any further locking past this point. 1217 */ 1218 p->p_stat = SIDL; /* not even a zombie any more */ 1219 LIST_REMOVE(p, p_list); /* off zombproc */ 1220 parent->p_nstopchild--; 1221 LIST_REMOVE(p, p_sibling); 1222 1223 /* 1224 * Let pid be reallocated. 1225 */ 1226 proc_free_pid(p->p_pid); 1227 atomic_dec_uint(&nprocs); 1228 1229 /* 1230 * Unlink process from its process group. 1231 * Releases the proc_lock. 1232 */ 1233 proc_leavepgrp(p); 1234 1235 /* 1236 * Delay release until after lwp_free. 1237 */ 1238 cred2 = l->l_cred; 1239 1240 /* 1241 * Free the last LWP's resources. 1242 * 1243 * lwp_free ensures the LWP is no longer running on another CPU. 1244 */ 1245 lwp_free(l, false, true); 1246 1247 /* 1248 * Now no one except us can reach the process p. 1249 */ 1250 1251 /* 1252 * Decrement the count of procs running with this uid. 1253 */ 1254 cred1 = p->p_cred; 1255 uid = kauth_cred_getuid(cred1); 1256 (void)chgproccnt(uid, -1); 1257 1258 /* 1259 * Release substructures. 1260 */ 1261 1262 lim_free(p->p_limit); 1263 pstatsfree(p->p_stats); 1264 kauth_cred_free(cred1); 1265 kauth_cred_free(cred2); 1266 1267 /* 1268 * Release reference to text vnode 1269 */ 1270 if (p->p_textvp) 1271 vrele(p->p_textvp); 1272 kmem_strfree(p->p_path); 1273 1274 mutex_destroy(&p->p_auxlock); 1275 mutex_obj_free(p->p_lock); 1276 mutex_destroy(&p->p_stmutex); 1277 cv_destroy(&p->p_waitcv); 1278 cv_destroy(&p->p_lwpcv); 1279 rw_destroy(&p->p_reflock); 1280 1281 proc_free_mem(p); 1282 } 1283 1284 /* 1285 * Change the parent of a process for tracing purposes. 1286 */ 1287 void 1288 proc_changeparent(struct proc *t, struct proc *p) 1289 { 1290 SET(t->p_slflag, PSL_TRACED); 1291 t->p_opptr = t->p_pptr; 1292 if (t->p_pptr == p) 1293 return; 1294 struct proc *parent = t->p_pptr; 1295 1296 if (parent->p_lock < t->p_lock) { 1297 if (!mutex_tryenter(parent->p_lock)) { 1298 mutex_exit(t->p_lock); 1299 mutex_enter(parent->p_lock); 1300 mutex_enter(t->p_lock); 1301 } 1302 } else if (parent->p_lock > t->p_lock) { 1303 mutex_enter(parent->p_lock); 1304 } 1305 parent->p_slflag |= PSL_CHTRACED; 1306 proc_reparent(t, p); 1307 if (parent->p_lock != t->p_lock) 1308 mutex_exit(parent->p_lock); 1309 } 1310 1311 /* 1312 * make process 'parent' the new parent of process 'child'. 1313 * 1314 * Must be called with proc_lock held. 1315 */ 1316 void 1317 proc_reparent(struct proc *child, struct proc *parent) 1318 { 1319 1320 KASSERT(mutex_owned(&proc_lock)); 1321 1322 if (child->p_pptr == parent) 1323 return; 1324 1325 if (child->p_stat == SZOMB || child->p_stat == SDEAD || 1326 (child->p_stat == SSTOP && !child->p_waited)) { 1327 child->p_pptr->p_nstopchild--; 1328 parent->p_nstopchild++; 1329 } 1330 if (parent == initproc) { 1331 child->p_exitsig = SIGCHLD; 1332 child->p_ppid = parent->p_pid; 1333 } 1334 1335 LIST_REMOVE(child, p_sibling); 1336 LIST_INSERT_HEAD(&parent->p_children, child, p_sibling); 1337 child->p_pptr = parent; 1338 } 1339