/* $NetBSD: kern_exit.c,v 1.291 2020/12/05 18:17:01 thorpej Exp $ */ /*- * Copyright (c) 1998, 1999, 2006, 2007, 2008, 2020 The NetBSD Foundation, Inc. * All rights reserved. * * This code is derived from software contributed to The NetBSD Foundation * by Jason R. Thorpe of the Numerical Aerospace Simulation Facility, * NASA Ames Research Center, and by Andrew Doran. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE * POSSIBILITY OF SUCH DAMAGE. */ /* * Copyright (c) 1982, 1986, 1989, 1991, 1993 * The Regents of the University of California. All rights reserved. * (c) UNIX System Laboratories, Inc. * All or some portions of this file are derived from material licensed * to the University of California by American Telephone and Telegraph * Co. or Unix System Laboratories, Inc. and are reproduced herein with * the permission of UNIX System Laboratories, Inc. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. Neither the name of the University nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. * * @(#)kern_exit.c 8.10 (Berkeley) 2/23/95 */ #include __KERNEL_RCSID(0, "$NetBSD: kern_exit.c,v 1.291 2020/12/05 18:17:01 thorpej Exp $"); #include "opt_ktrace.h" #include "opt_dtrace.h" #include "opt_sysv.h" #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #ifdef DEBUG_EXIT int debug_exit = 0; #define DPRINTF(x) if (debug_exit) printf x #else #define DPRINTF(x) #endif static int find_stopped_child(struct proc *, idtype_t, id_t, int, struct proc **, struct wrusage *, siginfo_t *); static void proc_free(struct proc *, struct wrusage *); /* * DTrace SDT provider definitions */ SDT_PROVIDER_DECLARE(proc); SDT_PROBE_DEFINE1(proc, kernel, , exit, "int"); /* * Fill in the appropriate signal information, and signal the parent. */ /* XXX noclone works around a gcc 4.5 bug on arm */ static void __noclone exit_psignal(struct proc *p, struct proc *pp, ksiginfo_t *ksi) { KSI_INIT(ksi); if ((ksi->ksi_signo = P_EXITSIG(p)) == SIGCHLD) { if (p->p_xsig) { if (p->p_sflag & PS_COREDUMP) ksi->ksi_code = CLD_DUMPED; else ksi->ksi_code = CLD_KILLED; ksi->ksi_status = p->p_xsig; } else { ksi->ksi_code = CLD_EXITED; ksi->ksi_status = p->p_xexit; } } else { ksi->ksi_code = SI_USER; ksi->ksi_status = p->p_xsig; } /* * We fill those in, even for non-SIGCHLD. * It's safe to access p->p_cred unlocked here. */ ksi->ksi_pid = p->p_pid; ksi->ksi_uid = kauth_cred_geteuid(p->p_cred); /* XXX: is this still valid? */ ksi->ksi_utime = p->p_stats->p_ru.ru_utime.tv_sec; ksi->ksi_stime = p->p_stats->p_ru.ru_stime.tv_sec; } /* * exit -- * Death of process. */ int sys_exit(struct lwp *l, const struct sys_exit_args *uap, register_t *retval) { /* { syscallarg(int) rval; } */ struct proc *p = l->l_proc; /* Don't call exit1() multiple times in the same process. */ mutex_enter(p->p_lock); if (p->p_sflag & PS_WEXIT) { mutex_exit(p->p_lock); lwp_exit(l); } /* exit1() will release the mutex. */ exit1(l, SCARG(uap, rval), 0); /* NOTREACHED */ return (0); } /* * Exit: deallocate address space and other resources, change proc state * to zombie, and unlink proc from allproc and parent's lists. Save exit * status and rusage for wait(). Check for child processes and orphan them. * * Must be called with p->p_lock held. Does not return. */ void exit1(struct lwp *l, int exitcode, int signo) { struct proc *p, *child, *next_child, *old_parent, *new_parent; struct pgrp *pgrp; ksiginfo_t ksi; ksiginfoq_t kq; int wakeinit; p = l->l_proc; /* Verify that we hold no locks other than p->p_lock. */ LOCKDEBUG_BARRIER(p->p_lock, 0); /* XXX Temporary: something is leaking kernel_lock. */ KERNEL_UNLOCK_ALL(l, NULL); KASSERT(mutex_owned(p->p_lock)); KASSERT(p->p_vmspace != NULL); if (__predict_false(p == initproc)) { panic("init died (signal %d, exit %d)", signo, exitcode); } p->p_sflag |= PS_WEXIT; /* * Force all other LWPs to exit before we do. Only then can we * begin to tear down the rest of the process state. */ if (p->p_nlwps > 1) { exit_lwps(l); } ksiginfo_queue_init(&kq); /* * If we have been asked to stop on exit, do so now. */ if (__predict_false(p->p_sflag & PS_STOPEXIT)) { KERNEL_UNLOCK_ALL(l, &l->l_biglocks); sigclearall(p, &contsigmask, &kq); if (!mutex_tryenter(&proc_lock)) { mutex_exit(p->p_lock); mutex_enter(&proc_lock); mutex_enter(p->p_lock); } p->p_waited = 0; p->p_pptr->p_nstopchild++; p->p_stat = SSTOP; mutex_exit(&proc_lock); lwp_lock(l); p->p_nrlwps--; l->l_stat = LSSTOP; lwp_unlock(l); mutex_exit(p->p_lock); lwp_lock(l); spc_lock(l->l_cpu); mi_switch(l); mutex_enter(p->p_lock); } /* * Bin any remaining signals and mark the process as dying so it will * not be found for, e.g. signals. */ sigfillset(&p->p_sigctx.ps_sigignore); sigclearall(p, NULL, &kq); p->p_stat = SDYING; /* * Perform any required thread cleanup. Do this early so * anyone wanting to look us up by our global thread ID * will fail to find us. * * N.B. this will unlock p->p_lock on our behalf. */ lwp_thread_cleanup(l); ksiginfo_queue_drain(&kq); /* Destroy any lwpctl info. */ if (p->p_lwpctl != NULL) lwp_ctl_exit(); /* * Drain all remaining references that procfs, ptrace and others may * have on the process. */ rw_enter(&p->p_reflock, RW_WRITER); DPRINTF(("%s: %d.%d exiting.\n", __func__, p->p_pid, l->l_lid)); ptimers_free(p, TIMERS_ALL); #if defined(__HAVE_RAS) ras_purgeall(); #endif /* * Close open files, release open-file table and free signal * actions. This may block! */ fd_free(); cwdfree(p->p_cwdi); p->p_cwdi = NULL; doexithooks(p); sigactsfree(p->p_sigacts); /* * Write out accounting data. */ (void)acct_process(l); #ifdef KTRACE /* * Release trace file. */ if (p->p_tracep != NULL) { mutex_enter(&ktrace_lock); ktrderef(p); mutex_exit(&ktrace_lock); } #endif p->p_xexit = exitcode; p->p_xsig = signo; /* * If emulation has process exit hook, call it now. * Set the exit status now so that the exit hook has * an opportunity to tweak it (COMPAT_LINUX requires * this for thread group emulation) */ if (p->p_emul->e_proc_exit) (*p->p_emul->e_proc_exit)(p); /* * Free the VM resources we're still holding on to. * We must do this from a valid thread because doing * so may block. This frees vmspace, which we don't * need anymore. The only remaining lwp is the one * we run at this moment, nothing runs in userland * anymore. */ ruspace(p); /* Update our vm resource use */ uvm_proc_exit(p); /* * Stop profiling. */ if (__predict_false((p->p_stflag & PST_PROFIL) != 0)) { mutex_spin_enter(&p->p_stmutex); stopprofclock(p); mutex_spin_exit(&p->p_stmutex); } /* * If parent is waiting for us to exit or exec, PL_PPWAIT is set; we * wake up the parent early to avoid deadlock. We can do this once * the VM resources are released. */ mutex_enter(&proc_lock); if (p->p_lflag & PL_PPWAIT) { lwp_t *lp; l->l_lwpctl = NULL; /* was on loan from blocked parent */ p->p_lflag &= ~PL_PPWAIT; lp = p->p_vforklwp; p->p_vforklwp = NULL; lp->l_vforkwaiting = false; cv_broadcast(&lp->l_waitcv); } if (SESS_LEADER(p)) { struct vnode *vprele = NULL, *vprevoke = NULL; struct session *sp = p->p_session; struct tty *tp; if (sp->s_ttyvp) { /* * Controlling process. * Signal foreground pgrp, * drain controlling terminal * and revoke access to controlling terminal. */ tp = sp->s_ttyp; mutex_spin_enter(&tty_lock); if (tp->t_session == sp) { /* we can't guarantee the revoke will do this */ pgrp = tp->t_pgrp; tp->t_pgrp = NULL; tp->t_session = NULL; mutex_spin_exit(&tty_lock); if (pgrp != NULL) { pgsignal(pgrp, SIGHUP, 1); } mutex_exit(&proc_lock); (void) ttywait(tp); mutex_enter(&proc_lock); /* The tty could have been revoked. */ vprevoke = sp->s_ttyvp; } else mutex_spin_exit(&tty_lock); vprele = sp->s_ttyvp; sp->s_ttyvp = NULL; /* * s_ttyp is not zero'd; we use this to indicate * that the session once had a controlling terminal. * (for logging and informational purposes) */ } sp->s_leader = NULL; if (vprevoke != NULL || vprele != NULL) { if (vprevoke != NULL) { /* Releases proc_lock. */ proc_sessrele(sp); VOP_REVOKE(vprevoke, REVOKEALL); } else mutex_exit(&proc_lock); if (vprele != NULL) vrele(vprele); mutex_enter(&proc_lock); } } fixjobc(p, p->p_pgrp, 0); /* Release fstrans private data. */ fstrans_lwp_dtor(l); /* * Finalize the last LWP's specificdata, as well as the * specificdata for the proc itself. */ lwp_finispecific(l); proc_finispecific(p); /* * Notify interested parties of our demise. */ KNOTE(&p->p_klist, NOTE_EXIT); SDT_PROBE(proc, kernel, , exit, ((p->p_sflag & PS_COREDUMP) ? CLD_DUMPED : (p->p_xsig ? CLD_KILLED : CLD_EXITED)), 0,0,0,0); /* * Reset p_opptr pointer of all former children which got * traced by another process and were reparented. We reset * it to NULL here; the trace detach code then reparents * the child to initproc. We only check allproc list, since * eventual former children on zombproc list won't reference * p_opptr anymore. */ if (__predict_false(p->p_slflag & PSL_CHTRACED)) { struct proc *q; PROCLIST_FOREACH(q, &allproc) { if (q->p_opptr == p) q->p_opptr = NULL; } PROCLIST_FOREACH(q, &zombproc) { if (q->p_opptr == p) q->p_opptr = NULL; } } /* * Give orphaned children to init(8). */ child = LIST_FIRST(&p->p_children); wakeinit = (child != NULL); for (; child != NULL; child = next_child) { next_child = LIST_NEXT(child, p_sibling); /* * Traced processes are killed since their existence * means someone is screwing up. Since we reset the * trace flags, the logic in sys_wait4() would not be * triggered to reparent the process to its * original parent, so we must do this here. */ if (__predict_false(child->p_slflag & PSL_TRACED)) { mutex_enter(p->p_lock); child->p_slflag &= ~(PSL_TRACED|PSL_SYSCALL); mutex_exit(p->p_lock); if (child->p_opptr != child->p_pptr) { struct proc *t = child->p_opptr; proc_reparent(child, t ? t : initproc); child->p_opptr = NULL; } else proc_reparent(child, initproc); killproc(child, "orphaned traced process"); } else proc_reparent(child, initproc); } /* * Move proc from allproc to zombproc, it's now nearly ready to be * collected by parent. */ LIST_REMOVE(l, l_list); LIST_REMOVE(p, p_list); LIST_INSERT_HEAD(&zombproc, p, p_list); /* * Mark the process as dead. We must do this before we signal * the parent. */ p->p_stat = SDEAD; /* Put in front of parent's sibling list for parent to collect it */ old_parent = p->p_pptr; old_parent->p_nstopchild++; if (LIST_FIRST(&old_parent->p_children) != p) { /* Put child where it can be found quickly */ LIST_REMOVE(p, p_sibling); LIST_INSERT_HEAD(&old_parent->p_children, p, p_sibling); } /* * Notify parent that we're gone. If parent has the P_NOCLDWAIT * flag set, notify init instead (and hope it will handle * this situation). */ if (old_parent->p_flag & (PK_NOCLDWAIT|PK_CLDSIGIGN)) { proc_reparent(p, initproc); wakeinit = 1; /* * If this was the last child of our parent, notify * parent, so in case he was wait(2)ing, he will * continue. */ if (LIST_FIRST(&old_parent->p_children) == NULL) cv_broadcast(&old_parent->p_waitcv); } /* Reload parent pointer, since p may have been reparented above */ new_parent = p->p_pptr; if (__predict_false(p->p_exitsig != 0)) { exit_psignal(p, new_parent, &ksi); kpsignal(new_parent, &ksi, NULL); } /* Calculate the final rusage info. */ calcru(p, &p->p_stats->p_ru.ru_utime, &p->p_stats->p_ru.ru_stime, NULL, NULL); if (wakeinit) cv_broadcast(&initproc->p_waitcv); callout_destroy(&l->l_timeout_ch); /* * Release any PCU resources before becoming a zombie. */ pcu_discard_all(l); mutex_enter(p->p_lock); /* Free the LWP ID */ proc_free_lwpid(p, l->l_lid); lwp_drainrefs(l); lwp_lock(l); l->l_prflag &= ~LPR_DETACHED; l->l_stat = LSZOMB; lwp_unlock(l); KASSERT(curlwp == l); KASSERT(p->p_nrlwps == 1); KASSERT(p->p_nlwps == 1); p->p_stat = SZOMB; p->p_nrlwps--; p->p_nzlwps++; p->p_ndlwps = 0; mutex_exit(p->p_lock); /* * Signal the parent to collect us, and drop the proclist lock. * Drop debugger/procfs lock; no new references can be gained. */ cv_broadcast(&p->p_pptr->p_waitcv); rw_exit(&p->p_reflock); mutex_exit(&proc_lock); /* * NOTE: WE ARE NO LONGER ALLOWED TO SLEEP! */ /* * Give machine-dependent code a chance to free any MD LWP * resources. This must be done before uvm_lwp_exit(), in * case these resources are in the PCB. */ cpu_lwp_free(l, 1); /* Switch away into oblivion. */ lwp_lock(l); spc_lock(l->l_cpu); mi_switch(l); panic("exit1"); } void exit_lwps(struct lwp *l) { proc_t *p = l->l_proc; lwp_t *l2; retry: KASSERT(mutex_owned(p->p_lock)); /* * Interrupt LWPs in interruptable sleep, unsuspend suspended * LWPs and then wait for everyone else to finish. */ LIST_FOREACH(l2, &p->p_lwps, l_sibling) { if (l2 == l) continue; lwp_lock(l2); l2->l_flag |= LW_WEXIT; if ((l2->l_stat == LSSLEEP && (l2->l_flag & LW_SINTR)) || l2->l_stat == LSSUSPENDED || l2->l_stat == LSSTOP) { l2->l_flag &= ~LW_DBGSUSPEND; /* setrunnable() will release the lock. */ setrunnable(l2); continue; } lwp_need_userret(l2); lwp_unlock(l2); } /* * Wait for every LWP to exit. Note: LWPs can get suspended/slept * behind us or there may even be new LWPs created. Therefore, a * full retry is required on error. */ while (p->p_nlwps > 1) { if (lwp_wait(l, 0, NULL, true)) { goto retry; } } KASSERT(p->p_nlwps == 1); } int do_sys_waitid(idtype_t idtype, id_t id, int *pid, int *status, int options, struct wrusage *wru, siginfo_t *si) { proc_t *child; int error; if (wru != NULL) memset(wru, 0, sizeof(*wru)); if (si != NULL) memset(si, 0, sizeof(*si)); mutex_enter(&proc_lock); error = find_stopped_child(curproc, idtype, id, options, &child, wru, si); if (child == NULL) { mutex_exit(&proc_lock); *pid = 0; *status = 0; return error; } *pid = child->p_pid; if (child->p_stat == SZOMB) { /* Child is exiting */ *status = P_WAITSTATUS(child); /* proc_free() will release the proc_lock. */ if (options & WNOWAIT) { mutex_exit(&proc_lock); } else { proc_free(child, wru); } } else { /* Don't mark SIGCONT if we are being stopped */ *status = (child->p_xsig == SIGCONT && child->p_stat != SSTOP) ? W_CONTCODE() : W_STOPCODE(child->p_xsig); mutex_exit(&proc_lock); } return 0; } int do_sys_wait(int *pid, int *status, int options, struct rusage *ru) { idtype_t idtype; id_t id; int ret; struct wrusage wru; /* * Translate the special pid values into the (idtype, pid) * pair for wait6. The WAIT_MYPGRP case is handled by * find_stopped_child() on its own. */ if (*pid == WAIT_ANY) { idtype = P_ALL; id = 0; } else if (*pid < 0) { idtype = P_PGID; id = (id_t)-*pid; } else { idtype = P_PID; id = (id_t)*pid; } options |= WEXITED | WTRAPPED; ret = do_sys_waitid(idtype, id, pid, status, options, ru ? &wru : NULL, NULL); if (ru) *ru = wru.wru_self; return ret; } int sys___wait450(struct lwp *l, const struct sys___wait450_args *uap, register_t *retval) { /* { syscallarg(int) pid; syscallarg(int *) status; syscallarg(int) options; syscallarg(struct rusage *) rusage; } */ int error, status, pid = SCARG(uap, pid); struct rusage ru; error = do_sys_wait(&pid, &status, SCARG(uap, options), SCARG(uap, rusage) != NULL ? &ru : NULL); retval[0] = pid; if (pid == 0) { return error; } if (SCARG(uap, status)) { error = copyout(&status, SCARG(uap, status), sizeof(status)); } if (SCARG(uap, rusage) && error == 0) { error = copyout(&ru, SCARG(uap, rusage), sizeof(ru)); } return error; } int sys_wait6(struct lwp *l, const struct sys_wait6_args *uap, register_t *retval) { /* { syscallarg(idtype_t) idtype; syscallarg(id_t) id; syscallarg(int *) status; syscallarg(int) options; syscallarg(struct wrusage *) wru; syscallarg(siginfo_t *) si; } */ struct wrusage wru, *wrup; siginfo_t si, *sip; idtype_t idtype; int pid; id_t id; int error, status; idtype = SCARG(uap, idtype); id = SCARG(uap, id); if (SCARG(uap, wru) != NULL) wrup = &wru; else wrup = NULL; if (SCARG(uap, info) != NULL) sip = &si; else sip = NULL; /* * We expect all callers of wait6() to know about WEXITED and * WTRAPPED. */ error = do_sys_waitid(idtype, id, &pid, &status, SCARG(uap, options), wrup, sip); retval[0] = pid; /* tell userland who it was */ #if 0 /* * should we copyout if there was no process, hence no useful data? * We don't for an old sytle wait4() (etc) but I believe * FreeBSD does for wait6(), so a tossup... Go with FreeBSD for now. */ if (pid == 0) return error; #endif if (SCARG(uap, status) != NULL && error == 0) error = copyout(&status, SCARG(uap, status), sizeof(status)); if (SCARG(uap, wru) != NULL && error == 0) error = copyout(&wru, SCARG(uap, wru), sizeof(wru)); if (SCARG(uap, info) != NULL && error == 0) error = copyout(&si, SCARG(uap, info), sizeof(si)); return error; } /* * Find a process that matches the provided criteria, and fill siginfo * and resources if found. * Returns: * -1: Not found, abort early * 0: Not matched * 1: Matched, there might be more matches * 2: This is the only match */ static int match_process(const struct proc *pp, struct proc **q, idtype_t idtype, id_t id, int options, struct wrusage *wrusage, siginfo_t *siginfo) { struct rusage *rup; struct proc *p = *q; int rv = 1; mutex_enter(p->p_lock); switch (idtype) { case P_ALL: break; case P_PID: if (p->p_pid != (pid_t)id) { mutex_exit(p->p_lock); p = *q = proc_find_raw((pid_t)id); if (p == NULL || p->p_stat == SIDL || p->p_pptr != pp) { *q = NULL; return -1; } mutex_enter(p->p_lock); } rv++; break; case P_PGID: if (p->p_pgid != (pid_t)id) goto out; break; case P_SID: if (p->p_session->s_sid != (pid_t)id) goto out; break; case P_UID: if (kauth_cred_geteuid(p->p_cred) != (uid_t)id) goto out; break; case P_GID: if (kauth_cred_getegid(p->p_cred) != (gid_t)id) goto out; break; case P_CID: case P_PSETID: case P_CPUID: /* XXX: Implement me */ default: out: mutex_exit(p->p_lock); return 0; } if ((options & WEXITED) == 0 && p->p_stat == SZOMB) goto out; if (siginfo != NULL) { siginfo->si_errno = 0; /* * SUSv4 requires that the si_signo value is always * SIGCHLD. Obey it despite the rfork(2) interface * allows to request other signal for child exit * notification. */ siginfo->si_signo = SIGCHLD; /* * This is still a rough estimate. We will fix the * cases TRAPPED, STOPPED, and CONTINUED later. */ if (p->p_sflag & PS_COREDUMP) { siginfo->si_code = CLD_DUMPED; siginfo->si_status = p->p_xsig; } else if (p->p_xsig) { siginfo->si_code = CLD_KILLED; siginfo->si_status = p->p_xsig; } else { siginfo->si_code = CLD_EXITED; siginfo->si_status = p->p_xexit; } siginfo->si_pid = p->p_pid; siginfo->si_uid = kauth_cred_geteuid(p->p_cred); siginfo->si_utime = p->p_stats->p_ru.ru_utime.tv_sec; siginfo->si_stime = p->p_stats->p_ru.ru_stime.tv_sec; } /* * There should be no reason to limit resources usage info to * exited processes only. A snapshot about any resources used * by a stopped process may be exactly what is needed. */ if (wrusage != NULL) { rup = &wrusage->wru_self; *rup = p->p_stats->p_ru; calcru(p, &rup->ru_utime, &rup->ru_stime, NULL, NULL); rup = &wrusage->wru_children; *rup = p->p_stats->p_cru; calcru(p, &rup->ru_utime, &rup->ru_stime, NULL, NULL); } mutex_exit(p->p_lock); return rv; } /* * Determine if there are existing processes being debugged * that used to be (and sometime later will be again) children * of a specific parent (while matching wait criteria) */ static bool debugged_child_exists(idtype_t idtype, id_t id, int options, siginfo_t *si, const struct proc *parent) { struct proc *pp; /* * If we are searching for a specific pid, we can optimise a little */ if (idtype == P_PID) { /* * Check the specific process to see if its real parent is us */ pp = proc_find_raw((pid_t)id); if (pp != NULL && pp->p_stat != SIDL && pp->p_opptr == parent) { /* * using P_ALL here avoids match_process() doing the * same work that we just did, but incorrectly for * this scenario. */ if (match_process(parent, &pp, P_ALL, id, options, NULL, si)) return true; } return false; } /* * For the hard cases, just look everywhere to see if some * stolen (reparented) process is really our lost child. * Then check if that process could satisfy the wait conditions. */ /* * XXX inefficient, but hopefully fairly rare. * XXX should really use a list of reparented processes. */ PROCLIST_FOREACH(pp, &allproc) { if (pp->p_stat == SIDL) /* XXX impossible ?? */ continue; if (pp->p_opptr == parent && match_process(parent, &pp, idtype, id, options, NULL, si)) return true; } PROCLIST_FOREACH(pp, &zombproc) { if (pp->p_stat == SIDL) /* XXX impossible ?? */ continue; if (pp->p_opptr == parent && match_process(parent, &pp, idtype, id, options, NULL, si)) return true; } return false; } /* * Scan list of child processes for a child process that has stopped or * exited. Used by sys_wait4 and 'compat' equivalents. * * Must be called with the proc_lock held, and may release while waiting. */ static int find_stopped_child(struct proc *parent, idtype_t idtype, id_t id, int options, struct proc **child_p, struct wrusage *wru, siginfo_t *si) { struct proc *child, *dead; int error; KASSERT(mutex_owned(&proc_lock)); if (options & ~WALLOPTS) { *child_p = NULL; return EINVAL; } if ((options & WSELECTOPTS) == 0) { /* * We will be unable to find any matching processes, * because there are no known events to look for. * Prefer to return error instead of blocking * indefinitely. */ *child_p = NULL; return EINVAL; } if ((pid_t)id == WAIT_MYPGRP && (idtype == P_PID || idtype == P_PGID)) { mutex_enter(parent->p_lock); id = (id_t)parent->p_pgid; mutex_exit(parent->p_lock); idtype = P_PGID; } for (;;) { error = ECHILD; dead = NULL; LIST_FOREACH(child, &parent->p_children, p_sibling) { int rv = match_process(parent, &child, idtype, id, options, wru, si); if (rv == -1) break; if (rv == 0) continue; /* * Wait for processes with p_exitsig != SIGCHLD * processes only if WALTSIG is set; wait for * processes with p_exitsig == SIGCHLD only * if WALTSIG is clear. */ if (((options & WALLSIG) == 0) && (options & WALTSIG ? child->p_exitsig == SIGCHLD : P_EXITSIG(child) != SIGCHLD)){ if (rv == 2) { child = NULL; break; } continue; } error = 0; if ((options & WNOZOMBIE) == 0) { if (child->p_stat == SZOMB) break; if (child->p_stat == SDEAD) { /* * We may occasionally arrive here * after receiving a signal, but * immediately before the child * process is zombified. The wait * will be short, so avoid returning * to userspace. */ dead = child; } } if ((options & WCONTINUED) != 0 && child->p_xsig == SIGCONT && (child->p_sflag & PS_CONTINUED)) { if ((options & WNOWAIT) == 0) { child->p_sflag &= ~PS_CONTINUED; child->p_waited = 1; parent->p_nstopchild--; } if (si) { si->si_status = child->p_xsig; si->si_code = CLD_CONTINUED; } break; } if ((options & (WTRAPPED|WSTOPPED)) != 0 && child->p_stat == SSTOP && child->p_waited == 0 && ((child->p_slflag & PSL_TRACED) || options & (WUNTRACED|WSTOPPED))) { if ((options & WNOWAIT) == 0) { child->p_waited = 1; parent->p_nstopchild--; } if (si) { si->si_status = child->p_xsig; si->si_code = (child->p_slflag & PSL_TRACED) ? CLD_TRAPPED : CLD_STOPPED; } break; } if (parent->p_nstopchild == 0 || rv == 2) { child = NULL; break; } } /* * If we found nothing, but we are the bereaved parent * of a stolen child, look and see if that child (or * one of them) meets our search criteria. If so, then * we cannot succeed, but we can hang (wait...), * or if WNOHANG, return 0 instead of ECHILD */ if (child == NULL && error == ECHILD && (parent->p_slflag & PSL_CHTRACED) && debugged_child_exists(idtype, id, options, si, parent)) error = 0; if (child != NULL || error != 0 || ((options & WNOHANG) != 0 && dead == NULL)) { *child_p = child; return error; } /* * Wait for another child process to stop. */ error = cv_wait_sig(&parent->p_waitcv, &proc_lock); if (error != 0) { *child_p = NULL; return error; } } } /* * Free a process after parent has taken all the state info. Must be called * with the proclist lock held, and will release before returning. * * *ru is returned to the caller, and must be freed by the caller. */ static void proc_free(struct proc *p, struct wrusage *wru) { struct proc *parent = p->p_pptr; struct lwp *l; ksiginfo_t ksi; kauth_cred_t cred1, cred2; uid_t uid; KASSERT(mutex_owned(&proc_lock)); KASSERT(p->p_nlwps == 1); KASSERT(p->p_nzlwps == 1); KASSERT(p->p_nrlwps == 0); KASSERT(p->p_stat == SZOMB); /* * If we got the child via ptrace(2) or procfs, and * the parent is different (meaning the process was * attached, rather than run as a child), then we need * to give it back to the old parent, and send the * parent the exit signal. The rest of the cleanup * will be done when the old parent waits on the child. */ if ((p->p_slflag & PSL_TRACED) != 0 && p->p_opptr != parent) { mutex_enter(p->p_lock); p->p_slflag &= ~(PSL_TRACED|PSL_SYSCALL); mutex_exit(p->p_lock); parent = (p->p_opptr == NULL) ? initproc : p->p_opptr; proc_reparent(p, parent); p->p_opptr = NULL; if (p->p_exitsig != 0) { exit_psignal(p, parent, &ksi); kpsignal(parent, &ksi, NULL); } cv_broadcast(&parent->p_waitcv); mutex_exit(&proc_lock); return; } sched_proc_exit(parent, p); /* * Add child times of exiting process onto its own times. * This cannot be done any earlier else it might get done twice. */ l = LIST_FIRST(&p->p_lwps); p->p_stats->p_ru.ru_nvcsw += (l->l_ncsw - l->l_nivcsw); p->p_stats->p_ru.ru_nivcsw += l->l_nivcsw; ruadd(&p->p_stats->p_ru, &l->l_ru); ruadd(&p->p_stats->p_ru, &p->p_stats->p_cru); ruadd(&parent->p_stats->p_cru, &p->p_stats->p_ru); if (wru != NULL) { wru->wru_self = p->p_stats->p_ru; wru->wru_children = p->p_stats->p_cru; } p->p_xsig = 0; p->p_xexit = 0; /* * At this point we are going to start freeing the final resources. * If anyone tries to access the proc structure after here they will * get a shock - bits are missing. Attempt to make it hard! We * don't bother with any further locking past this point. */ p->p_stat = SIDL; /* not even a zombie any more */ LIST_REMOVE(p, p_list); /* off zombproc */ parent->p_nstopchild--; LIST_REMOVE(p, p_sibling); /* * Let pid be reallocated. */ proc_free_pid(p->p_pid); atomic_dec_uint(&nprocs); /* * Unlink process from its process group. * Releases the proc_lock. */ proc_leavepgrp(p); /* * Delay release until after lwp_free. */ cred2 = l->l_cred; /* * Free the last LWP's resources. * * lwp_free ensures the LWP is no longer running on another CPU. */ lwp_free(l, false, true); /* * Now no one except us can reach the process p. */ /* * Decrement the count of procs running with this uid. */ cred1 = p->p_cred; uid = kauth_cred_getuid(cred1); (void)chgproccnt(uid, -1); /* * Release substructures. */ lim_free(p->p_limit); pstatsfree(p->p_stats); kauth_cred_free(cred1); kauth_cred_free(cred2); /* * Release reference to text vnode */ if (p->p_textvp) vrele(p->p_textvp); kmem_strfree(p->p_path); mutex_destroy(&p->p_auxlock); mutex_obj_free(p->p_lock); mutex_destroy(&p->p_stmutex); cv_destroy(&p->p_waitcv); cv_destroy(&p->p_lwpcv); rw_destroy(&p->p_reflock); proc_free_mem(p); } /* * Change the parent of a process for tracing purposes. */ void proc_changeparent(struct proc *t, struct proc *p) { SET(t->p_slflag, PSL_TRACED); t->p_opptr = t->p_pptr; if (t->p_pptr == p) return; struct proc *parent = t->p_pptr; if (parent->p_lock < t->p_lock) { if (!mutex_tryenter(parent->p_lock)) { mutex_exit(t->p_lock); mutex_enter(parent->p_lock); mutex_enter(t->p_lock); } } else if (parent->p_lock > t->p_lock) { mutex_enter(parent->p_lock); } parent->p_slflag |= PSL_CHTRACED; proc_reparent(t, p); if (parent->p_lock != t->p_lock) mutex_exit(parent->p_lock); } /* * make process 'parent' the new parent of process 'child'. * * Must be called with proc_lock held. */ void proc_reparent(struct proc *child, struct proc *parent) { KASSERT(mutex_owned(&proc_lock)); if (child->p_pptr == parent) return; if (child->p_stat == SZOMB || child->p_stat == SDEAD || (child->p_stat == SSTOP && !child->p_waited)) { child->p_pptr->p_nstopchild--; parent->p_nstopchild++; } if (parent == initproc) { child->p_exitsig = SIGCHLD; child->p_ppid = parent->p_pid; } LIST_REMOVE(child, p_sibling); LIST_INSERT_HEAD(&parent->p_children, child, p_sibling); child->p_pptr = parent; }