/* $NetBSD: kern_sig.c,v 1.378 2019/11/10 14:20:50 pgoyette Exp $ */ /*- * Copyright (c) 2006, 2007, 2008 The NetBSD Foundation, Inc. * All rights reserved. * * This code is derived from software contributed to The NetBSD Foundation * 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_sig.c 8.14 (Berkeley) 5/14/95 */ /* * Signal subsystem. */ #include __KERNEL_RCSID(0, "$NetBSD: kern_sig.c,v 1.378 2019/11/10 14:20:50 pgoyette Exp $"); #include "opt_ptrace.h" #include "opt_dtrace.h" #include "opt_compat_sunos.h" #include "opt_compat_netbsd.h" #include "opt_compat_netbsd32.h" #include "opt_pax.h" #define SIGPROP /* include signal properties table */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #ifdef PAX_SEGVGUARD #include #endif /* PAX_SEGVGUARD */ #include #define SIGQUEUE_MAX 32 static pool_cache_t sigacts_cache __read_mostly; static pool_cache_t ksiginfo_cache __read_mostly; static callout_t proc_stop_ch __cacheline_aligned; sigset_t contsigmask __cacheline_aligned; sigset_t stopsigmask __cacheline_aligned; static sigset_t vforksigmask __cacheline_aligned; sigset_t sigcantmask __cacheline_aligned; static void ksiginfo_exechook(struct proc *, void *); static void proc_stop(struct proc *, int); static void proc_stop_done(struct proc *, int); static void proc_stop_callout(void *); static int sigchecktrace(void); static int sigpost(struct lwp *, sig_t, int, int); static int sigput(sigpend_t *, struct proc *, ksiginfo_t *); static int sigunwait(struct proc *, const ksiginfo_t *); static void sigswitch(int, int, bool); static void sigswitch_unlock_and_switch_away(struct lwp *); static void sigacts_poolpage_free(struct pool *, void *); static void *sigacts_poolpage_alloc(struct pool *, int); /* * DTrace SDT provider definitions */ SDT_PROVIDER_DECLARE(proc); SDT_PROBE_DEFINE3(proc, kernel, , signal__send, "struct lwp *", /* target thread */ "struct proc *", /* target process */ "int"); /* signal */ SDT_PROBE_DEFINE3(proc, kernel, , signal__discard, "struct lwp *", /* target thread */ "struct proc *", /* target process */ "int"); /* signal */ SDT_PROBE_DEFINE3(proc, kernel, , signal__handle, "int", /* signal */ "ksiginfo_t *", /* signal info */ "void (*)(void)"); /* handler address */ static struct pool_allocator sigactspool_allocator = { .pa_alloc = sigacts_poolpage_alloc, .pa_free = sigacts_poolpage_free }; #ifdef DEBUG int kern_logsigexit = 1; #else int kern_logsigexit = 0; #endif static const char logcoredump[] = "pid %d (%s), uid %d: exited on signal %d (core dumped)\n"; static const char lognocoredump[] = "pid %d (%s), uid %d: exited on signal %d (core not dumped, err = %d)\n"; static kauth_listener_t signal_listener; static int signal_listener_cb(kauth_cred_t cred, kauth_action_t action, void *cookie, void *arg0, void *arg1, void *arg2, void *arg3) { struct proc *p; int result, signum; result = KAUTH_RESULT_DEFER; p = arg0; signum = (int)(unsigned long)arg1; if (action != KAUTH_PROCESS_SIGNAL) return result; if (kauth_cred_uidmatch(cred, p->p_cred) || (signum == SIGCONT && (curproc->p_session == p->p_session))) result = KAUTH_RESULT_ALLOW; return result; } static int sigacts_ctor(void *arg __unused, void *obj, int flags __unused) { memset(obj, 0, sizeof(struct sigacts)); return 0; } /* * signal_init: * * Initialize global signal-related data structures. */ void signal_init(void) { sigactspool_allocator.pa_pagesz = (PAGE_SIZE)*2; sigacts_cache = pool_cache_init(sizeof(struct sigacts), 0, 0, 0, "sigacts", sizeof(struct sigacts) > PAGE_SIZE ? &sigactspool_allocator : NULL, IPL_NONE, sigacts_ctor, NULL, NULL); ksiginfo_cache = pool_cache_init(sizeof(ksiginfo_t), 0, 0, 0, "ksiginfo", NULL, IPL_VM, NULL, NULL, NULL); exechook_establish(ksiginfo_exechook, NULL); callout_init(&proc_stop_ch, CALLOUT_MPSAFE); callout_setfunc(&proc_stop_ch, proc_stop_callout, NULL); signal_listener = kauth_listen_scope(KAUTH_SCOPE_PROCESS, signal_listener_cb, NULL); } /* * sigacts_poolpage_alloc: * * Allocate a page for the sigacts memory pool. */ static void * sigacts_poolpage_alloc(struct pool *pp, int flags) { return (void *)uvm_km_alloc(kernel_map, PAGE_SIZE * 2, PAGE_SIZE * 2, ((flags & PR_WAITOK) ? 0 : UVM_KMF_NOWAIT | UVM_KMF_TRYLOCK) | UVM_KMF_WIRED); } /* * sigacts_poolpage_free: * * Free a page on behalf of the sigacts memory pool. */ static void sigacts_poolpage_free(struct pool *pp, void *v) { uvm_km_free(kernel_map, (vaddr_t)v, PAGE_SIZE * 2, UVM_KMF_WIRED); } /* * sigactsinit: * * Create an initial sigacts structure, using the same signal state * as of specified process. If 'share' is set, share the sigacts by * holding a reference, otherwise just copy it from parent. */ struct sigacts * sigactsinit(struct proc *pp, int share) { struct sigacts *ps = pp->p_sigacts, *ps2; if (__predict_false(share)) { atomic_inc_uint(&ps->sa_refcnt); return ps; } ps2 = pool_cache_get(sigacts_cache, PR_WAITOK); mutex_init(&ps2->sa_mutex, MUTEX_DEFAULT, IPL_SCHED); ps2->sa_refcnt = 1; mutex_enter(&ps->sa_mutex); memcpy(ps2->sa_sigdesc, ps->sa_sigdesc, sizeof(ps2->sa_sigdesc)); mutex_exit(&ps->sa_mutex); return ps2; } /* * sigactsunshare: * * Make this process not share its sigacts, maintaining all signal state. */ void sigactsunshare(struct proc *p) { struct sigacts *ps, *oldps = p->p_sigacts; if (__predict_true(oldps->sa_refcnt == 1)) return; ps = pool_cache_get(sigacts_cache, PR_WAITOK); mutex_init(&ps->sa_mutex, MUTEX_DEFAULT, IPL_SCHED); memcpy(ps->sa_sigdesc, oldps->sa_sigdesc, sizeof(ps->sa_sigdesc)); ps->sa_refcnt = 1; p->p_sigacts = ps; sigactsfree(oldps); } /* * sigactsfree; * * Release a sigacts structure. */ void sigactsfree(struct sigacts *ps) { if (atomic_dec_uint_nv(&ps->sa_refcnt) == 0) { mutex_destroy(&ps->sa_mutex); pool_cache_put(sigacts_cache, ps); } } /* * siginit: * * Initialize signal state for process 0; set to ignore signals that * are ignored by default and disable the signal stack. Locking not * required as the system is still cold. */ void siginit(struct proc *p) { struct lwp *l; struct sigacts *ps; int signo, prop; ps = p->p_sigacts; sigemptyset(&contsigmask); sigemptyset(&stopsigmask); sigemptyset(&vforksigmask); sigemptyset(&sigcantmask); for (signo = 1; signo < NSIG; signo++) { prop = sigprop[signo]; if (prop & SA_CONT) sigaddset(&contsigmask, signo); if (prop & SA_STOP) sigaddset(&stopsigmask, signo); if (prop & SA_STOP && signo != SIGSTOP) sigaddset(&vforksigmask, signo); if (prop & SA_CANTMASK) sigaddset(&sigcantmask, signo); if (prop & SA_IGNORE && signo != SIGCONT) sigaddset(&p->p_sigctx.ps_sigignore, signo); sigemptyset(&SIGACTION_PS(ps, signo).sa_mask); SIGACTION_PS(ps, signo).sa_flags = SA_RESTART; } sigemptyset(&p->p_sigctx.ps_sigcatch); p->p_sflag &= ~PS_NOCLDSTOP; ksiginfo_queue_init(&p->p_sigpend.sp_info); sigemptyset(&p->p_sigpend.sp_set); /* * Reset per LWP state. */ l = LIST_FIRST(&p->p_lwps); l->l_sigwaited = NULL; l->l_sigstk = SS_INIT; ksiginfo_queue_init(&l->l_sigpend.sp_info); sigemptyset(&l->l_sigpend.sp_set); /* One reference. */ ps->sa_refcnt = 1; } /* * execsigs: * * Reset signals for an exec of the specified process. */ void execsigs(struct proc *p) { struct sigacts *ps; struct lwp *l; int signo, prop; sigset_t tset; ksiginfoq_t kq; KASSERT(p->p_nlwps == 1); sigactsunshare(p); ps = p->p_sigacts; /* * Reset caught signals. Held signals remain held through * l->l_sigmask (unless they were caught, and are now ignored * by default). * * No need to lock yet, the process has only one LWP and * at this point the sigacts are private to the process. */ sigemptyset(&tset); for (signo = 1; signo < NSIG; signo++) { if (sigismember(&p->p_sigctx.ps_sigcatch, signo)) { prop = sigprop[signo]; if (prop & SA_IGNORE) { if ((prop & SA_CONT) == 0) sigaddset(&p->p_sigctx.ps_sigignore, signo); sigaddset(&tset, signo); } SIGACTION_PS(ps, signo).sa_handler = SIG_DFL; } sigemptyset(&SIGACTION_PS(ps, signo).sa_mask); SIGACTION_PS(ps, signo).sa_flags = SA_RESTART; } ksiginfo_queue_init(&kq); mutex_enter(p->p_lock); sigclearall(p, &tset, &kq); sigemptyset(&p->p_sigctx.ps_sigcatch); /* * Reset no zombies if child dies flag as Solaris does. */ p->p_flag &= ~(PK_NOCLDWAIT | PK_CLDSIGIGN); if (SIGACTION_PS(ps, SIGCHLD).sa_handler == SIG_IGN) SIGACTION_PS(ps, SIGCHLD).sa_handler = SIG_DFL; /* * Reset per-LWP state. */ l = LIST_FIRST(&p->p_lwps); l->l_sigwaited = NULL; l->l_sigstk = SS_INIT; ksiginfo_queue_init(&l->l_sigpend.sp_info); sigemptyset(&l->l_sigpend.sp_set); mutex_exit(p->p_lock); ksiginfo_queue_drain(&kq); } /* * ksiginfo_exechook: * * Free all pending ksiginfo entries from a process on exec. * Additionally, drain any unused ksiginfo structures in the * system back to the pool. * * XXX This should not be a hook, every process has signals. */ static void ksiginfo_exechook(struct proc *p, void *v) { ksiginfoq_t kq; ksiginfo_queue_init(&kq); mutex_enter(p->p_lock); sigclearall(p, NULL, &kq); mutex_exit(p->p_lock); ksiginfo_queue_drain(&kq); } /* * ksiginfo_alloc: * * Allocate a new ksiginfo structure from the pool, and optionally copy * an existing one. If the existing ksiginfo_t is from the pool, and * has not been queued somewhere, then just return it. Additionally, * if the existing ksiginfo_t does not contain any information beyond * the signal number, then just return it. */ ksiginfo_t * ksiginfo_alloc(struct proc *p, ksiginfo_t *ok, int flags) { ksiginfo_t *kp; if (ok != NULL) { if ((ok->ksi_flags & (KSI_QUEUED | KSI_FROMPOOL)) == KSI_FROMPOOL) return ok; if (KSI_EMPTY_P(ok)) return ok; } kp = pool_cache_get(ksiginfo_cache, flags); if (kp == NULL) { #ifdef DIAGNOSTIC printf("Out of memory allocating ksiginfo for pid %d\n", p->p_pid); #endif return NULL; } if (ok != NULL) { memcpy(kp, ok, sizeof(*kp)); kp->ksi_flags &= ~KSI_QUEUED; } else KSI_INIT_EMPTY(kp); kp->ksi_flags |= KSI_FROMPOOL; return kp; } /* * ksiginfo_free: * * If the given ksiginfo_t is from the pool and has not been queued, * then free it. */ void ksiginfo_free(ksiginfo_t *kp) { if ((kp->ksi_flags & (KSI_QUEUED | KSI_FROMPOOL)) != KSI_FROMPOOL) return; pool_cache_put(ksiginfo_cache, kp); } /* * ksiginfo_queue_drain: * * Drain a non-empty ksiginfo_t queue. */ void ksiginfo_queue_drain0(ksiginfoq_t *kq) { ksiginfo_t *ksi; KASSERT(!TAILQ_EMPTY(kq)); while (!TAILQ_EMPTY(kq)) { ksi = TAILQ_FIRST(kq); TAILQ_REMOVE(kq, ksi, ksi_list); pool_cache_put(ksiginfo_cache, ksi); } } static int siggetinfo(sigpend_t *sp, ksiginfo_t *out, int signo) { ksiginfo_t *ksi, *nksi; if (sp == NULL) goto out; /* Find siginfo and copy it out. */ int count = 0; TAILQ_FOREACH_SAFE(ksi, &sp->sp_info, ksi_list, nksi) { if (ksi->ksi_signo != signo) continue; if (count++ > 0) /* Only remove the first, count all of them */ continue; TAILQ_REMOVE(&sp->sp_info, ksi, ksi_list); KASSERT((ksi->ksi_flags & KSI_FROMPOOL) != 0); KASSERT((ksi->ksi_flags & KSI_QUEUED) != 0); ksi->ksi_flags &= ~KSI_QUEUED; if (out != NULL) { memcpy(out, ksi, sizeof(*out)); out->ksi_flags &= ~(KSI_FROMPOOL | KSI_QUEUED); } ksiginfo_free(ksi); } if (count) return count; out: /* If there is no siginfo, then manufacture it. */ if (out != NULL) { KSI_INIT(out); out->ksi_info._signo = signo; out->ksi_info._code = SI_NOINFO; } return 0; } /* * sigget: * * Fetch the first pending signal from a set. Optionally, also fetch * or manufacture a ksiginfo element. Returns the number of the first * pending signal, or zero. */ int sigget(sigpend_t *sp, ksiginfo_t *out, int signo, const sigset_t *mask) { sigset_t tset; int count; /* If there's no pending set, the signal is from the debugger. */ if (sp == NULL) goto out; /* Construct mask from signo, and 'mask'. */ if (signo == 0) { if (mask != NULL) { tset = *mask; __sigandset(&sp->sp_set, &tset); } else tset = sp->sp_set; /* If there are no signals pending - return. */ if ((signo = firstsig(&tset)) == 0) goto out; } else { KASSERT(sigismember(&sp->sp_set, signo)); } sigdelset(&sp->sp_set, signo); out: count = siggetinfo(sp, out, signo); if (count > 1) sigaddset(&sp->sp_set, signo); return signo; } /* * sigput: * * Append a new ksiginfo element to the list of pending ksiginfo's. */ static int sigput(sigpend_t *sp, struct proc *p, ksiginfo_t *ksi) { ksiginfo_t *kp; KASSERT(mutex_owned(p->p_lock)); KASSERT((ksi->ksi_flags & KSI_QUEUED) == 0); sigaddset(&sp->sp_set, ksi->ksi_signo); /* * If there is no siginfo, we are done. */ if (KSI_EMPTY_P(ksi)) return 0; KASSERT((ksi->ksi_flags & KSI_FROMPOOL) != 0); size_t count = 0; TAILQ_FOREACH(kp, &sp->sp_info, ksi_list) { count++; if (ksi->ksi_signo >= SIGRTMIN && ksi->ksi_signo <= SIGRTMAX) continue; if (kp->ksi_signo == ksi->ksi_signo) { KSI_COPY(ksi, kp); kp->ksi_flags |= KSI_QUEUED; return 0; } } if (count >= SIGQUEUE_MAX) { #ifdef DIAGNOSTIC printf("%s(%d): Signal queue is full signal=%d\n", p->p_comm, p->p_pid, ksi->ksi_signo); #endif return EAGAIN; } ksi->ksi_flags |= KSI_QUEUED; TAILQ_INSERT_TAIL(&sp->sp_info, ksi, ksi_list); return 0; } /* * sigclear: * * Clear all pending signals in the specified set. */ void sigclear(sigpend_t *sp, const sigset_t *mask, ksiginfoq_t *kq) { ksiginfo_t *ksi, *next; if (mask == NULL) sigemptyset(&sp->sp_set); else sigminusset(mask, &sp->sp_set); TAILQ_FOREACH_SAFE(ksi, &sp->sp_info, ksi_list, next) { if (mask == NULL || sigismember(mask, ksi->ksi_signo)) { TAILQ_REMOVE(&sp->sp_info, ksi, ksi_list); KASSERT((ksi->ksi_flags & KSI_FROMPOOL) != 0); KASSERT((ksi->ksi_flags & KSI_QUEUED) != 0); TAILQ_INSERT_TAIL(kq, ksi, ksi_list); } } } /* * sigclearall: * * Clear all pending signals in the specified set from a process and * its LWPs. */ void sigclearall(struct proc *p, const sigset_t *mask, ksiginfoq_t *kq) { struct lwp *l; KASSERT(mutex_owned(p->p_lock)); sigclear(&p->p_sigpend, mask, kq); LIST_FOREACH(l, &p->p_lwps, l_sibling) { sigclear(&l->l_sigpend, mask, kq); } } /* * sigispending: * * Return the first signal number if there are pending signals for the * current LWP. May be called unlocked provided that LW_PENDSIG is set, * and that the signal has been posted to the appopriate queue before * LW_PENDSIG is set. */ int sigispending(struct lwp *l, int signo) { struct proc *p = l->l_proc; sigset_t tset; membar_consumer(); tset = l->l_sigpend.sp_set; sigplusset(&p->p_sigpend.sp_set, &tset); sigminusset(&p->p_sigctx.ps_sigignore, &tset); sigminusset(&l->l_sigmask, &tset); if (signo == 0) { return firstsig(&tset); } return sigismember(&tset, signo) ? signo : 0; } void getucontext(struct lwp *l, ucontext_t *ucp) { struct proc *p = l->l_proc; KASSERT(mutex_owned(p->p_lock)); ucp->uc_flags = 0; ucp->uc_link = l->l_ctxlink; ucp->uc_sigmask = l->l_sigmask; ucp->uc_flags |= _UC_SIGMASK; /* * The (unsupplied) definition of the `current execution stack' * in the System V Interface Definition appears to allow returning * the main context stack. */ if ((l->l_sigstk.ss_flags & SS_ONSTACK) == 0) { ucp->uc_stack.ss_sp = (void *)l->l_proc->p_stackbase; ucp->uc_stack.ss_size = ctob(l->l_proc->p_vmspace->vm_ssize); ucp->uc_stack.ss_flags = 0; /* XXX, def. is Very Fishy */ } else { /* Simply copy alternate signal execution stack. */ ucp->uc_stack = l->l_sigstk; } ucp->uc_flags |= _UC_STACK; mutex_exit(p->p_lock); cpu_getmcontext(l, &ucp->uc_mcontext, &ucp->uc_flags); mutex_enter(p->p_lock); } int setucontext(struct lwp *l, const ucontext_t *ucp) { struct proc *p = l->l_proc; int error; KASSERT(mutex_owned(p->p_lock)); if ((ucp->uc_flags & _UC_SIGMASK) != 0) { error = sigprocmask1(l, SIG_SETMASK, &ucp->uc_sigmask, NULL); if (error != 0) return error; } mutex_exit(p->p_lock); error = cpu_setmcontext(l, &ucp->uc_mcontext, ucp->uc_flags); mutex_enter(p->p_lock); if (error != 0) return (error); l->l_ctxlink = ucp->uc_link; /* * If there was stack information, update whether or not we are * still running on an alternate signal stack. */ if ((ucp->uc_flags & _UC_STACK) != 0) { if (ucp->uc_stack.ss_flags & SS_ONSTACK) l->l_sigstk.ss_flags |= SS_ONSTACK; else l->l_sigstk.ss_flags &= ~SS_ONSTACK; } return 0; } /* * killpg1: common code for kill process group/broadcast kill. */ int killpg1(struct lwp *l, ksiginfo_t *ksi, int pgid, int all) { struct proc *p, *cp; kauth_cred_t pc; struct pgrp *pgrp; int nfound; int signo = ksi->ksi_signo; cp = l->l_proc; pc = l->l_cred; nfound = 0; mutex_enter(proc_lock); if (all) { /* * Broadcast. */ PROCLIST_FOREACH(p, &allproc) { if (p->p_pid <= 1 || p == cp || (p->p_flag & PK_SYSTEM) != 0) continue; mutex_enter(p->p_lock); if (kauth_authorize_process(pc, KAUTH_PROCESS_SIGNAL, p, KAUTH_ARG(signo), NULL, NULL) == 0) { nfound++; if (signo) kpsignal2(p, ksi); } mutex_exit(p->p_lock); } } else { if (pgid == 0) /* Zero pgid means send to my process group. */ pgrp = cp->p_pgrp; else { pgrp = pgrp_find(pgid); if (pgrp == NULL) goto out; } LIST_FOREACH(p, &pgrp->pg_members, p_pglist) { if (p->p_pid <= 1 || p->p_flag & PK_SYSTEM) continue; mutex_enter(p->p_lock); if (kauth_authorize_process(pc, KAUTH_PROCESS_SIGNAL, p, KAUTH_ARG(signo), NULL, NULL) == 0) { nfound++; if (signo && P_ZOMBIE(p) == 0) kpsignal2(p, ksi); } mutex_exit(p->p_lock); } } out: mutex_exit(proc_lock); return nfound ? 0 : ESRCH; } /* * Send a signal to a process group. If checktty is set, limit to members * which have a controlling terminal. */ void pgsignal(struct pgrp *pgrp, int sig, int checkctty) { ksiginfo_t ksi; KASSERT(!cpu_intr_p()); KASSERT(mutex_owned(proc_lock)); KSI_INIT_EMPTY(&ksi); ksi.ksi_signo = sig; kpgsignal(pgrp, &ksi, NULL, checkctty); } void kpgsignal(struct pgrp *pgrp, ksiginfo_t *ksi, void *data, int checkctty) { struct proc *p; KASSERT(!cpu_intr_p()); KASSERT(mutex_owned(proc_lock)); KASSERT(pgrp != NULL); LIST_FOREACH(p, &pgrp->pg_members, p_pglist) if (checkctty == 0 || p->p_lflag & PL_CONTROLT) kpsignal(p, ksi, data); } /* * Send a signal caused by a trap to the current LWP. If it will be caught * immediately, deliver it with correct code. Otherwise, post it normally. */ void trapsignal(struct lwp *l, ksiginfo_t *ksi) { struct proc *p; struct sigacts *ps; int signo = ksi->ksi_signo; sigset_t *mask; sig_t action; KASSERT(KSI_TRAP_P(ksi)); ksi->ksi_lid = l->l_lid; p = l->l_proc; KASSERT(!cpu_intr_p()); mutex_enter(proc_lock); mutex_enter(p->p_lock); repeat: /* * If we are exiting, demise now. * * This avoids notifying tracer and deadlocking. */ if (__predict_false(ISSET(p->p_sflag, PS_WEXIT))) { mutex_exit(p->p_lock); mutex_exit(proc_lock); lwp_exit(l); panic("trapsignal"); /* NOTREACHED */ } /* * The process is already stopping. */ if ((p->p_sflag & PS_STOPPING) != 0) { mutex_exit(proc_lock); sigswitch_unlock_and_switch_away(l); mutex_enter(proc_lock); mutex_enter(p->p_lock); goto repeat; } mask = &l->l_sigmask; ps = p->p_sigacts; action = SIGACTION_PS(ps, signo).sa_handler; if (ISSET(p->p_slflag, PSL_TRACED) && !(p->p_pptr == p->p_opptr && ISSET(p->p_lflag, PL_PPWAIT)) && p->p_xsig != SIGKILL && !sigismember(&p->p_sigpend.sp_set, SIGKILL)) { p->p_xsig = signo; p->p_sigctx.ps_faked = true; p->p_sigctx.ps_lwp = ksi->ksi_lid; p->p_sigctx.ps_info = ksi->ksi_info; sigswitch(0, signo, true); if (ktrpoint(KTR_PSIG)) { if (p->p_emul->e_ktrpsig) p->p_emul->e_ktrpsig(signo, action, mask, ksi); else ktrpsig(signo, action, mask, ksi); } return; } const bool caught = sigismember(&p->p_sigctx.ps_sigcatch, signo); const bool masked = sigismember(mask, signo); if (caught && !masked) { mutex_exit(proc_lock); l->l_ru.ru_nsignals++; kpsendsig(l, ksi, mask); mutex_exit(p->p_lock); if (ktrpoint(KTR_PSIG)) { if (p->p_emul->e_ktrpsig) p->p_emul->e_ktrpsig(signo, action, mask, ksi); else ktrpsig(signo, action, mask, ksi); } return; } /* * If the signal is masked or ignored, then unmask it and * reset it to the default action so that the process or * its tracer will be notified. */ const bool ignored = action == SIG_IGN; if (masked || ignored) { mutex_enter(&ps->sa_mutex); sigdelset(mask, signo); sigdelset(&p->p_sigctx.ps_sigcatch, signo); sigdelset(&p->p_sigctx.ps_sigignore, signo); sigdelset(&SIGACTION_PS(ps, signo).sa_mask, signo); SIGACTION_PS(ps, signo).sa_handler = SIG_DFL; mutex_exit(&ps->sa_mutex); } kpsignal2(p, ksi); mutex_exit(p->p_lock); mutex_exit(proc_lock); } /* * Fill in signal information and signal the parent for a child status change. */ void child_psignal(struct proc *p, int mask) { ksiginfo_t ksi; struct proc *q; int xsig; KASSERT(mutex_owned(proc_lock)); KASSERT(mutex_owned(p->p_lock)); xsig = p->p_xsig; KSI_INIT(&ksi); ksi.ksi_signo = SIGCHLD; ksi.ksi_code = (xsig == SIGCONT ? CLD_CONTINUED : CLD_STOPPED); ksi.ksi_pid = p->p_pid; ksi.ksi_uid = kauth_cred_geteuid(p->p_cred); ksi.ksi_status = xsig; ksi.ksi_utime = p->p_stats->p_ru.ru_utime.tv_sec; ksi.ksi_stime = p->p_stats->p_ru.ru_stime.tv_sec; q = p->p_pptr; mutex_exit(p->p_lock); mutex_enter(q->p_lock); if ((q->p_sflag & mask) == 0) kpsignal2(q, &ksi); mutex_exit(q->p_lock); mutex_enter(p->p_lock); } void psignal(struct proc *p, int signo) { ksiginfo_t ksi; KASSERT(!cpu_intr_p()); KASSERT(mutex_owned(proc_lock)); KSI_INIT_EMPTY(&ksi); ksi.ksi_signo = signo; mutex_enter(p->p_lock); kpsignal2(p, &ksi); mutex_exit(p->p_lock); } void kpsignal(struct proc *p, ksiginfo_t *ksi, void *data) { fdfile_t *ff; file_t *fp; fdtab_t *dt; KASSERT(!cpu_intr_p()); KASSERT(mutex_owned(proc_lock)); if ((p->p_sflag & PS_WEXIT) == 0 && data) { size_t fd; filedesc_t *fdp = p->p_fd; /* XXXSMP locking */ ksi->ksi_fd = -1; dt = fdp->fd_dt; for (fd = 0; fd < dt->dt_nfiles; fd++) { if ((ff = dt->dt_ff[fd]) == NULL) continue; if ((fp = ff->ff_file) == NULL) continue; if (fp->f_data == data) { ksi->ksi_fd = fd; break; } } } mutex_enter(p->p_lock); kpsignal2(p, ksi); mutex_exit(p->p_lock); } /* * sigismasked: * * Returns true if signal is ignored or masked for the specified LWP. */ int sigismasked(struct lwp *l, int sig) { struct proc *p = l->l_proc; return sigismember(&p->p_sigctx.ps_sigignore, sig) || sigismember(&l->l_sigmask, sig); } /* * sigpost: * * Post a pending signal to an LWP. Returns non-zero if the LWP may * be able to take the signal. */ static int sigpost(struct lwp *l, sig_t action, int prop, int sig) { int rv, masked; struct proc *p = l->l_proc; KASSERT(mutex_owned(p->p_lock)); /* * If the LWP is on the way out, sigclear() will be busy draining all * pending signals. Don't give it more. */ if (l->l_refcnt == 0) return 0; SDT_PROBE(proc, kernel, , signal__send, l, p, sig, 0, 0); lwp_lock(l); if (__predict_false((l->l_flag & LW_DBGSUSPEND) != 0)) { if ((prop & SA_KILL) != 0) l->l_flag &= ~LW_DBGSUSPEND; else { lwp_unlock(l); return 0; } } /* * Have the LWP check for signals. This ensures that even if no LWP * is found to take the signal immediately, it should be taken soon. */ l->l_flag |= LW_PENDSIG; /* * SIGCONT can be masked, but if LWP is stopped, it needs restart. * Note: SIGKILL and SIGSTOP cannot be masked. */ masked = sigismember(&l->l_sigmask, sig); if (masked && ((prop & SA_CONT) == 0 || l->l_stat != LSSTOP)) { lwp_unlock(l); return 0; } /* * If killing the process, make it run fast. */ if (__predict_false((prop & SA_KILL) != 0) && action == SIG_DFL && l->l_priority < MAXPRI_USER) { KASSERT(l->l_class == SCHED_OTHER); lwp_changepri(l, MAXPRI_USER); } /* * If the LWP is running or on a run queue, then we win. If it's * sleeping interruptably, wake it and make it take the signal. If * the sleep isn't interruptable, then the chances are it will get * to see the signal soon anyhow. If suspended, it can't take the * signal right now. If it's LWP private or for all LWPs, save it * for later; otherwise punt. */ rv = 0; switch (l->l_stat) { case LSRUN: case LSONPROC: lwp_need_userret(l); rv = 1; break; case LSSLEEP: if ((l->l_flag & LW_SINTR) != 0) { /* setrunnable() will release the lock. */ setrunnable(l); return 1; } break; case LSSUSPENDED: if ((prop & SA_KILL) != 0 && (l->l_flag & LW_WCORE) != 0) { /* lwp_continue() will release the lock. */ lwp_continue(l); return 1; } break; case LSSTOP: if ((prop & SA_STOP) != 0) break; /* * If the LWP is stopped and we are sending a continue * signal, then start it again. */ if ((prop & SA_CONT) != 0) { if (l->l_wchan != NULL) { l->l_stat = LSSLEEP; p->p_nrlwps++; rv = 1; break; } /* setrunnable() will release the lock. */ setrunnable(l); return 1; } else if (l->l_wchan == NULL || (l->l_flag & LW_SINTR) != 0) { /* setrunnable() will release the lock. */ setrunnable(l); return 1; } break; default: break; } lwp_unlock(l); return rv; } /* * Notify an LWP that it has a pending signal. */ void signotify(struct lwp *l) { KASSERT(lwp_locked(l, NULL)); l->l_flag |= LW_PENDSIG; lwp_need_userret(l); } /* * Find an LWP within process p that is waiting on signal ksi, and hand * it on. */ static int sigunwait(struct proc *p, const ksiginfo_t *ksi) { struct lwp *l; int signo; KASSERT(mutex_owned(p->p_lock)); signo = ksi->ksi_signo; if (ksi->ksi_lid != 0) { /* * Signal came via _lwp_kill(). Find the LWP and see if * it's interested. */ if ((l = lwp_find(p, ksi->ksi_lid)) == NULL) return 0; if (l->l_sigwaited == NULL || !sigismember(&l->l_sigwaitset, signo)) return 0; } else { /* * Look for any LWP that may be interested. */ LIST_FOREACH(l, &p->p_sigwaiters, l_sigwaiter) { KASSERT(l->l_sigwaited != NULL); if (sigismember(&l->l_sigwaitset, signo)) break; } } if (l != NULL) { l->l_sigwaited->ksi_info = ksi->ksi_info; l->l_sigwaited = NULL; LIST_REMOVE(l, l_sigwaiter); cv_signal(&l->l_sigcv); return 1; } return 0; } /* * Send the signal to the process. If the signal has an action, the action * is usually performed by the target process rather than the caller; we add * the signal to the set of pending signals for the process. * * Exceptions: * o When a stop signal is sent to a sleeping process that takes the * default action, the process is stopped without awakening it. * o SIGCONT restarts stopped processes (or puts them back to sleep) * regardless of the signal action (eg, blocked or ignored). * * Other ignored signals are discarded immediately. */ int kpsignal2(struct proc *p, ksiginfo_t *ksi) { int prop, signo = ksi->ksi_signo; struct lwp *l = NULL; ksiginfo_t *kp; lwpid_t lid; sig_t action; bool toall; int error = 0; KASSERT(!cpu_intr_p()); KASSERT(mutex_owned(proc_lock)); KASSERT(mutex_owned(p->p_lock)); KASSERT((ksi->ksi_flags & KSI_QUEUED) == 0); KASSERT(signo > 0 && signo < NSIG); /* * If the process is being created by fork, is a zombie or is * exiting, then just drop the signal here and bail out. */ if (p->p_stat != SACTIVE && p->p_stat != SSTOP) return 0; /* * Notify any interested parties of the signal. */ KNOTE(&p->p_klist, NOTE_SIGNAL | signo); /* * Some signals including SIGKILL must act on the entire process. */ kp = NULL; prop = sigprop[signo]; toall = ((prop & SA_TOALL) != 0); lid = toall ? 0 : ksi->ksi_lid; /* * If proc is traced, always give parent a chance. */ if (p->p_slflag & PSL_TRACED) { action = SIG_DFL; if (lid == 0) { /* * If the process is being traced and the signal * is being caught, make sure to save any ksiginfo. */ if ((kp = ksiginfo_alloc(p, ksi, PR_NOWAIT)) == NULL) goto discard; if ((error = sigput(&p->p_sigpend, p, kp)) != 0) goto out; } } else { /* * If the signal is being ignored, then drop it. Note: we * don't set SIGCONT in ps_sigignore, and if it is set to * SIG_IGN, action will be SIG_DFL here. */ if (sigismember(&p->p_sigctx.ps_sigignore, signo)) goto discard; else if (sigismember(&p->p_sigctx.ps_sigcatch, signo)) action = SIG_CATCH; else { action = SIG_DFL; /* * If sending a tty stop signal to a member of an * orphaned process group, discard the signal here if * the action is default; don't stop the process below * if sleeping, and don't clear any pending SIGCONT. */ if (prop & SA_TTYSTOP && p->p_pgrp->pg_jobc == 0) goto discard; if (prop & SA_KILL && p->p_nice > NZERO) p->p_nice = NZERO; } } /* * If stopping or continuing a process, discard any pending * signals that would do the inverse. */ if ((prop & (SA_CONT | SA_STOP)) != 0) { ksiginfoq_t kq; ksiginfo_queue_init(&kq); if ((prop & SA_CONT) != 0) sigclear(&p->p_sigpend, &stopsigmask, &kq); if ((prop & SA_STOP) != 0) sigclear(&p->p_sigpend, &contsigmask, &kq); ksiginfo_queue_drain(&kq); /* XXXSMP */ } /* * If the signal doesn't have SA_CANTMASK (no override for SIGKILL, * please!), check if any LWPs are waiting on it. If yes, pass on * the signal info. The signal won't be processed further here. */ if ((prop & SA_CANTMASK) == 0 && !LIST_EMPTY(&p->p_sigwaiters) && p->p_stat == SACTIVE && (p->p_sflag & PS_STOPPING) == 0 && sigunwait(p, ksi)) goto discard; /* * XXXSMP Should be allocated by the caller, we're holding locks * here. */ if (kp == NULL && (kp = ksiginfo_alloc(p, ksi, PR_NOWAIT)) == NULL) goto discard; /* * LWP private signals are easy - just find the LWP and post * the signal to it. */ if (lid != 0) { l = lwp_find(p, lid); if (l != NULL) { if ((error = sigput(&l->l_sigpend, p, kp)) != 0) goto out; membar_producer(); if (sigpost(l, action, prop, kp->ksi_signo) != 0) signo = -1; } goto out; } /* * Some signals go to all LWPs, even if posted with _lwp_kill() * or for an SA process. */ if (p->p_stat == SACTIVE && (p->p_sflag & PS_STOPPING) == 0) { if ((p->p_slflag & PSL_TRACED) != 0) goto deliver; /* * If SIGCONT is default (or ignored) and process is * asleep, we are finished; the process should not * be awakened. */ if ((prop & SA_CONT) != 0 && action == SIG_DFL) goto out; } else { /* * Process is stopped or stopping. * - If traced, then no action is needed, unless killing. * - Run the process only if sending SIGCONT or SIGKILL. */ if ((p->p_slflag & PSL_TRACED) != 0 && signo != SIGKILL) { goto out; } if ((prop & SA_CONT) != 0 || signo == SIGKILL) { /* * Re-adjust p_nstopchild if the process was * stopped but not yet collected by its parent. */ if (p->p_stat == SSTOP && !p->p_waited) p->p_pptr->p_nstopchild--; p->p_stat = SACTIVE; p->p_sflag &= ~PS_STOPPING; if (p->p_slflag & PSL_TRACED) { KASSERT(signo == SIGKILL); goto deliver; } /* * Do not make signal pending if SIGCONT is default. * * If the process catches SIGCONT, let it handle the * signal itself (if waiting on event - process runs, * otherwise continues sleeping). */ if ((prop & SA_CONT) != 0) { p->p_xsig = SIGCONT; p->p_sflag |= PS_CONTINUED; child_psignal(p, 0); if (action == SIG_DFL) { KASSERT(signo != SIGKILL); goto deliver; } } } else if ((prop & SA_STOP) != 0) { /* * Already stopped, don't need to stop again. * (If we did the shell could get confused.) */ goto out; } } /* * Make signal pending. */ KASSERT((p->p_slflag & PSL_TRACED) == 0); if ((error = sigput(&p->p_sigpend, p, kp)) != 0) goto out; deliver: /* * Before we set LW_PENDSIG on any LWP, ensure that the signal is * visible on the per process list (for sigispending()). This * is unlikely to be needed in practice, but... */ membar_producer(); /* * Try to find an LWP that can take the signal. */ LIST_FOREACH(l, &p->p_lwps, l_sibling) { if (sigpost(l, action, prop, kp->ksi_signo) && !toall) break; } signo = -1; out: /* * If the ksiginfo wasn't used, then bin it. XXXSMP freeing memory * with locks held. The caller should take care of this. */ ksiginfo_free(kp); if (signo == -1) return error; discard: SDT_PROBE(proc, kernel, , signal__discard, l, p, signo, 0, 0); return error; } void kpsendsig(struct lwp *l, const ksiginfo_t *ksi, const sigset_t *mask) { struct proc *p = l->l_proc; KASSERT(mutex_owned(p->p_lock)); (*p->p_emul->e_sendsig)(ksi, mask); } /* * Stop any LWPs sleeping interruptably. */ static void proc_stop_lwps(struct proc *p) { struct lwp *l; KASSERT(mutex_owned(p->p_lock)); KASSERT((p->p_sflag & PS_STOPPING) != 0); LIST_FOREACH(l, &p->p_lwps, l_sibling) { lwp_lock(l); if (l->l_stat == LSSLEEP && (l->l_flag & LW_SINTR) != 0) { l->l_stat = LSSTOP; p->p_nrlwps--; } lwp_unlock(l); } } /* * Finish stopping of a process. Mark it stopped and notify the parent. * * Drop p_lock briefly if ppsig is true. */ static void proc_stop_done(struct proc *p, int ppmask) { KASSERT(mutex_owned(proc_lock)); KASSERT(mutex_owned(p->p_lock)); KASSERT((p->p_sflag & PS_STOPPING) != 0); KASSERT(p->p_nrlwps == 0 || (p->p_nrlwps == 1 && p == curproc)); p->p_sflag &= ~PS_STOPPING; p->p_stat = SSTOP; p->p_waited = 0; p->p_pptr->p_nstopchild++; /* child_psignal drops p_lock briefly. */ child_psignal(p, ppmask); cv_broadcast(&p->p_pptr->p_waitcv); } /* * Stop the current process and switch away to the debugger notifying * an event specific to a traced process only. */ void eventswitch(int code, int pe_report_event, int entity) { struct lwp *l = curlwp; struct proc *p = l->l_proc; struct sigacts *ps; sigset_t *mask; sig_t action; ksiginfo_t ksi; const int signo = SIGTRAP; KASSERT(mutex_owned(proc_lock)); KASSERT(mutex_owned(p->p_lock)); KASSERT(p->p_pptr != initproc); KASSERT(l->l_stat == LSONPROC); KASSERT(ISSET(p->p_slflag, PSL_TRACED)); KASSERT(!ISSET(l->l_flag, LW_SYSTEM)); KASSERT(p->p_nrlwps > 0); KASSERT((code == TRAP_CHLD) || (code == TRAP_LWP) || (code == TRAP_EXEC)); KASSERT((code != TRAP_CHLD) || (entity > 1)); /* prevent pid1 */ KASSERT((code != TRAP_LWP) || (entity > 0)); repeat: /* * If we are exiting, demise now. * * This avoids notifying tracer and deadlocking. */ if (__predict_false(ISSET(p->p_sflag, PS_WEXIT))) { mutex_exit(p->p_lock); mutex_exit(proc_lock); if (pe_report_event == PTRACE_LWP_EXIT) { /* Avoid double lwp_exit() and panic. */ return; } lwp_exit(l); panic("eventswitch"); /* NOTREACHED */ } /* * If we are no longer traced, abandon this event signal. * * This avoids killing a process after detaching the debugger. */ if (__predict_false(!ISSET(p->p_slflag, PSL_TRACED))) { mutex_exit(p->p_lock); mutex_exit(proc_lock); return; } /* * If there's a pending SIGKILL process it immediately. */ if (p->p_xsig == SIGKILL || sigismember(&p->p_sigpend.sp_set, SIGKILL)) { mutex_exit(p->p_lock); mutex_exit(proc_lock); return; } /* * The process is already stopping. */ if ((p->p_sflag & PS_STOPPING) != 0) { mutex_exit(proc_lock); sigswitch_unlock_and_switch_away(l); mutex_enter(proc_lock); mutex_enter(p->p_lock); goto repeat; } KSI_INIT_TRAP(&ksi); ksi.ksi_lid = l->l_lid; ksi.ksi_signo = signo; ksi.ksi_code = code; ksi.ksi_pe_report_event = pe_report_event; CTASSERT(sizeof(ksi.ksi_pe_other_pid) == sizeof(ksi.ksi_pe_lwp)); ksi.ksi_pe_other_pid = entity; /* Needed for ktrace */ ps = p->p_sigacts; action = SIGACTION_PS(ps, signo).sa_handler; mask = &l->l_sigmask; p->p_xsig = signo; p->p_sigctx.ps_faked = true; p->p_sigctx.ps_lwp = ksi.ksi_lid; p->p_sigctx.ps_info = ksi.ksi_info; sigswitch(0, signo, true); if (code == TRAP_CHLD) { mutex_enter(proc_lock); while (l->l_vforkwaiting) cv_wait(&l->l_waitcv, proc_lock); mutex_exit(proc_lock); } if (ktrpoint(KTR_PSIG)) { if (p->p_emul->e_ktrpsig) p->p_emul->e_ktrpsig(signo, action, mask, &ksi); else ktrpsig(signo, action, mask, &ksi); } } /* * Stop the current process and switch away when being stopped or traced. */ static void sigswitch(int ppmask, int signo, bool proc_lock_held) { struct lwp *l = curlwp; struct proc *p = l->l_proc; KASSERT(mutex_owned(p->p_lock)); KASSERT(l->l_stat == LSONPROC); KASSERT(p->p_nrlwps > 0); if (proc_lock_held) { KASSERT(mutex_owned(proc_lock)); } else { KASSERT(!mutex_owned(proc_lock)); } /* * On entry we know that the process needs to stop. If it's * the result of a 'sideways' stop signal that has been sourced * through issignal(), then stop other LWPs in the process too. */ if (p->p_stat == SACTIVE && (p->p_sflag & PS_STOPPING) == 0) { KASSERT(signo != 0); proc_stop(p, signo); KASSERT(p->p_nrlwps > 0); } /* * If we are the last live LWP, and the stop was a result of * a new signal, then signal the parent. */ if ((p->p_sflag & PS_STOPPING) != 0) { if (!proc_lock_held && !mutex_tryenter(proc_lock)) { mutex_exit(p->p_lock); mutex_enter(proc_lock); mutex_enter(p->p_lock); } if (p->p_nrlwps == 1 && (p->p_sflag & PS_STOPPING) != 0) { /* * Note that proc_stop_done() can drop * p->p_lock briefly. */ proc_stop_done(p, ppmask); } mutex_exit(proc_lock); } sigswitch_unlock_and_switch_away(l); } /* * Unlock and switch away. */ static void sigswitch_unlock_and_switch_away(struct lwp *l) { struct proc *p; int biglocks; p = l->l_proc; KASSERT(mutex_owned(p->p_lock)); KASSERT(!mutex_owned(proc_lock)); KASSERT(l->l_stat == LSONPROC); KASSERT(p->p_nrlwps > 0); KERNEL_UNLOCK_ALL(l, &biglocks); if (p->p_stat == SSTOP || (p->p_sflag & PS_STOPPING) != 0) { p->p_nrlwps--; lwp_lock(l); KASSERT(l->l_stat == LSONPROC || l->l_stat == LSSLEEP); l->l_stat = LSSTOP; lwp_unlock(l); } mutex_exit(p->p_lock); lwp_lock(l); mi_switch(l); KERNEL_LOCK(biglocks, l); } /* * Check for a signal from the debugger. */ static int sigchecktrace(void) { struct lwp *l = curlwp; struct proc *p = l->l_proc; int signo; KASSERT(mutex_owned(p->p_lock)); /* If there's a pending SIGKILL, process it immediately. */ if (sigismember(&p->p_sigpend.sp_set, SIGKILL)) return 0; /* * If we are no longer being traced, or the parent didn't * give us a signal, or we're stopping, look for more signals. */ if ((p->p_slflag & PSL_TRACED) == 0 || p->p_xsig == 0 || (p->p_sflag & PS_STOPPING) != 0) return 0; /* * If the new signal is being masked, look for other signals. * `p->p_sigctx.ps_siglist |= mask' is done in setrunnable(). */ signo = p->p_xsig; p->p_xsig = 0; if (sigismember(&l->l_sigmask, signo)) { signo = 0; } return signo; } /* * If the current process has received a signal (should be caught or cause * termination, should interrupt current syscall), return the signal number. * * Stop signals with default action are processed immediately, then cleared; * they aren't returned. This is checked after each entry to the system for * a syscall or trap. * * We will also return -1 if the process is exiting and the current LWP must * follow suit. */ int issignal(struct lwp *l) { struct proc *p; int siglwp, signo, prop; sigpend_t *sp; sigset_t ss; p = l->l_proc; sp = NULL; signo = 0; KASSERT(p == curproc); KASSERT(mutex_owned(p->p_lock)); for (;;) { /* Discard any signals that we have decided not to take. */ if (signo != 0) { (void)sigget(sp, NULL, signo, NULL); } /* * If the process is stopped/stopping, then stop ourselves * now that we're on the kernel/userspace boundary. When * we awaken, check for a signal from the debugger. */ if (p->p_stat == SSTOP || (p->p_sflag & PS_STOPPING) != 0) { sigswitch_unlock_and_switch_away(l); mutex_enter(p->p_lock); continue; } else if (p->p_stat == SACTIVE) signo = sigchecktrace(); else signo = 0; /* Signals from the debugger are "out of band". */ sp = NULL; /* * If the debugger didn't provide a signal, find a pending * signal from our set. Check per-LWP signals first, and * then per-process. */ if (signo == 0) { sp = &l->l_sigpend; ss = sp->sp_set; siglwp = l->l_lid; if ((p->p_lflag & PL_PPWAIT) != 0) sigminusset(&vforksigmask, &ss); sigminusset(&l->l_sigmask, &ss); if ((signo = firstsig(&ss)) == 0) { sp = &p->p_sigpend; ss = sp->sp_set; siglwp = 0; if ((p->p_lflag & PL_PPWAIT) != 0) sigminusset(&vforksigmask, &ss); sigminusset(&l->l_sigmask, &ss); if ((signo = firstsig(&ss)) == 0) { /* * No signal pending - clear the * indicator and bail out. */ lwp_lock(l); l->l_flag &= ~LW_PENDSIG; lwp_unlock(l); sp = NULL; break; } } } if (sp) { /* Overwrite process' signal context to correspond * to the currently reported LWP. This is necessary * for PT_GET_SIGINFO to report the correct signal when * multiple LWPs have pending signals. We do this only * when the signal comes from the queue, for signals * created by the debugger we assume it set correct * siginfo. */ ksiginfo_t *ksi = TAILQ_FIRST(&sp->sp_info); if (ksi) { p->p_sigctx.ps_lwp = ksi->ksi_lid; p->p_sigctx.ps_info = ksi->ksi_info; } else { p->p_sigctx.ps_lwp = siglwp; memset(&p->p_sigctx.ps_info, 0, sizeof(p->p_sigctx.ps_info)); p->p_sigctx.ps_info._signo = signo; p->p_sigctx.ps_info._code = SI_NOINFO; } } /* * We should see pending but ignored signals only if * we are being traced. */ if (sigismember(&p->p_sigctx.ps_sigignore, signo) && (p->p_slflag & PSL_TRACED) == 0) { /* Discard the signal. */ continue; } /* * If traced, always stop, and stay stopped until released * by the debugger. If the our parent is our debugger waiting * for us and we vforked, don't hang as we could deadlock. */ if (ISSET(p->p_slflag, PSL_TRACED) && signo != SIGKILL && !(ISSET(p->p_lflag, PL_PPWAIT) && (p->p_pptr == p->p_opptr))) { /* * Take the signal, but don't remove it from the * siginfo queue, because the debugger can send * it later. */ if (sp) sigdelset(&sp->sp_set, signo); p->p_xsig = signo; /* Handling of signal trace */ sigswitch(0, signo, false); mutex_enter(p->p_lock); /* Check for a signal from the debugger. */ if ((signo = sigchecktrace()) == 0) continue; /* Signals from the debugger are "out of band". */ sp = NULL; } prop = sigprop[signo]; /* * Decide whether the signal should be returned. */ switch ((long)SIGACTION(p, signo).sa_handler) { case (long)SIG_DFL: /* * Don't take default actions on system processes. */ if (p->p_pid <= 1) { #ifdef DIAGNOSTIC /* * Are you sure you want to ignore SIGSEGV * in init? XXX */ printf_nolog("Process (pid %d) got sig %d\n", p->p_pid, signo); #endif continue; } /* * If there is a pending stop signal to process with * default action, stop here, then clear the signal. * However, if process is member of an orphaned * process group, ignore tty stop signals. */ if (prop & SA_STOP) { /* * XXX Don't hold proc_lock for p_lflag, * but it's not a big deal. */ if ((ISSET(p->p_slflag, PSL_TRACED) && !(ISSET(p->p_lflag, PL_PPWAIT) && (p->p_pptr == p->p_opptr))) || ((p->p_lflag & PL_ORPHANPG) != 0 && prop & SA_TTYSTOP)) { /* Ignore the signal. */ continue; } /* Take the signal. */ (void)sigget(sp, NULL, signo, NULL); p->p_xsig = signo; p->p_sflag &= ~PS_CONTINUED; signo = 0; sigswitch(PS_NOCLDSTOP, p->p_xsig, false); mutex_enter(p->p_lock); } else if (prop & SA_IGNORE) { /* * Except for SIGCONT, shouldn't get here. * Default action is to ignore; drop it. */ continue; } break; case (long)SIG_IGN: #ifdef DEBUG_ISSIGNAL /* * Masking above should prevent us ever trying * to take action on an ignored signal other * than SIGCONT, unless process is traced. */ if ((prop & SA_CONT) == 0 && (p->p_slflag & PSL_TRACED) == 0) printf_nolog("issignal\n"); #endif continue; default: /* * This signal has an action, let postsig() process * it. */ break; } break; } l->l_sigpendset = sp; return signo; } /* * Take the action for the specified signal * from the current set of pending signals. */ void postsig(int signo) { struct lwp *l; struct proc *p; struct sigacts *ps; sig_t action; sigset_t *returnmask; ksiginfo_t ksi; l = curlwp; p = l->l_proc; ps = p->p_sigacts; KASSERT(mutex_owned(p->p_lock)); KASSERT(signo > 0); /* * Set the new mask value and also defer further occurrences of this * signal. * * Special case: user has done a sigsuspend. Here the current mask is * not of interest, but rather the mask from before the sigsuspend is * what we want restored after the signal processing is completed. */ if (l->l_sigrestore) { returnmask = &l->l_sigoldmask; l->l_sigrestore = 0; } else returnmask = &l->l_sigmask; /* * Commit to taking the signal before releasing the mutex. */ action = SIGACTION_PS(ps, signo).sa_handler; l->l_ru.ru_nsignals++; if (l->l_sigpendset == NULL) { /* From the debugger */ if (p->p_sigctx.ps_faked && signo == p->p_sigctx.ps_info._signo) { KSI_INIT(&ksi); ksi.ksi_info = p->p_sigctx.ps_info; ksi.ksi_lid = p->p_sigctx.ps_lwp; p->p_sigctx.ps_faked = false; } else { if (!siggetinfo(&l->l_sigpend, &ksi, signo)) (void)siggetinfo(&p->p_sigpend, &ksi, signo); } } else sigget(l->l_sigpendset, &ksi, signo, NULL); if (ktrpoint(KTR_PSIG)) { mutex_exit(p->p_lock); if (p->p_emul->e_ktrpsig) p->p_emul->e_ktrpsig(signo, action, returnmask, &ksi); else ktrpsig(signo, action, returnmask, &ksi); mutex_enter(p->p_lock); } SDT_PROBE(proc, kernel, , signal__handle, signo, &ksi, action, 0, 0); if (action == SIG_DFL) { /* * Default action, where the default is to kill * the process. (Other cases were ignored above.) */ sigexit(l, signo); return; } /* * If we get here, the signal must be caught. */ #ifdef DIAGNOSTIC if (action == SIG_IGN || sigismember(&l->l_sigmask, signo)) panic("postsig action"); #endif kpsendsig(l, &ksi, returnmask); } /* * sendsig: * * Default signal delivery method for NetBSD. */ void sendsig(const struct ksiginfo *ksi, const sigset_t *mask) { struct sigacts *sa; int sig; sig = ksi->ksi_signo; sa = curproc->p_sigacts; switch (sa->sa_sigdesc[sig].sd_vers) { case 0: case 1: /* Compat for 1.6 and earlier. */ MODULE_HOOK_CALL_VOID(sendsig_sigcontext_16_hook, (ksi, mask), break); return; case 2: case 3: sendsig_siginfo(ksi, mask); return; default: break; } printf("sendsig: bad version %d\n", sa->sa_sigdesc[sig].sd_vers); sigexit(curlwp, SIGILL); } /* * sendsig_reset: * * Reset the signal action. Called from emulation specific sendsig() * before unlocking to deliver the signal. */ void sendsig_reset(struct lwp *l, int signo) { struct proc *p = l->l_proc; struct sigacts *ps = p->p_sigacts; KASSERT(mutex_owned(p->p_lock)); p->p_sigctx.ps_lwp = 0; memset(&p->p_sigctx.ps_info, 0, sizeof(p->p_sigctx.ps_info)); mutex_enter(&ps->sa_mutex); sigplusset(&SIGACTION_PS(ps, signo).sa_mask, &l->l_sigmask); if (SIGACTION_PS(ps, signo).sa_flags & SA_RESETHAND) { sigdelset(&p->p_sigctx.ps_sigcatch, signo); if (signo != SIGCONT && sigprop[signo] & SA_IGNORE) sigaddset(&p->p_sigctx.ps_sigignore, signo); SIGACTION_PS(ps, signo).sa_handler = SIG_DFL; } mutex_exit(&ps->sa_mutex); } /* * Kill the current process for stated reason. */ void killproc(struct proc *p, const char *why) { KASSERT(mutex_owned(proc_lock)); log(LOG_ERR, "pid %d was killed: %s\n", p->p_pid, why); uprintf_locked("sorry, pid %d was killed: %s\n", p->p_pid, why); psignal(p, SIGKILL); } /* * Force the current process to exit with the specified signal, dumping core * if appropriate. We bypass the normal tests for masked and caught * signals, allowing unrecoverable failures to terminate the process without * changing signal state. Mark the accounting record with the signal * termination. If dumping core, save the signal number for the debugger. * Calls exit and does not return. */ void sigexit(struct lwp *l, int signo) { int exitsig, error, docore; struct proc *p; struct lwp *t; p = l->l_proc; KASSERT(mutex_owned(p->p_lock)); KERNEL_UNLOCK_ALL(l, NULL); /* * Don't permit coredump() multiple times in the same process. * Call back into sigexit, where we will be suspended until * the deed is done. Note that this is a recursive call, but * LW_WCORE will prevent us from coming back this way. */ if ((p->p_sflag & PS_WCORE) != 0) { lwp_lock(l); l->l_flag |= (LW_WCORE | LW_WEXIT | LW_WSUSPEND); lwp_unlock(l); mutex_exit(p->p_lock); lwp_userret(l); panic("sigexit 1"); /* NOTREACHED */ } /* If process is already on the way out, then bail now. */ if ((p->p_sflag & PS_WEXIT) != 0) { mutex_exit(p->p_lock); lwp_exit(l); panic("sigexit 2"); /* NOTREACHED */ } /* * Prepare all other LWPs for exit. If dumping core, suspend them * so that their registers are available long enough to be dumped. */ if ((docore = (sigprop[signo] & SA_CORE)) != 0) { p->p_sflag |= PS_WCORE; for (;;) { LIST_FOREACH(t, &p->p_lwps, l_sibling) { lwp_lock(t); if (t == l) { t->l_flag &= ~(LW_WSUSPEND | LW_DBGSUSPEND); lwp_unlock(t); continue; } t->l_flag |= (LW_WCORE | LW_WEXIT); lwp_suspend(l, t); } if (p->p_nrlwps == 1) break; /* * Kick any LWPs sitting in lwp_wait1(), and wait * for everyone else to stop before proceeding. */ p->p_nlwpwait++; cv_broadcast(&p->p_lwpcv); cv_wait(&p->p_lwpcv, p->p_lock); p->p_nlwpwait--; } } exitsig = signo; p->p_acflag |= AXSIG; memset(&p->p_sigctx.ps_info, 0, sizeof(p->p_sigctx.ps_info)); p->p_sigctx.ps_info._signo = signo; p->p_sigctx.ps_info._code = SI_NOINFO; if (docore) { mutex_exit(p->p_lock); MODULE_HOOK_CALL(coredump_hook, (l, NULL), enosys(), error); if (kern_logsigexit) { int uid = l->l_cred ? (int)kauth_cred_geteuid(l->l_cred) : -1; if (error) log(LOG_INFO, lognocoredump, p->p_pid, p->p_comm, uid, signo, error); else log(LOG_INFO, logcoredump, p->p_pid, p->p_comm, uid, signo); } #ifdef PAX_SEGVGUARD pax_segvguard(l, p->p_textvp, p->p_comm, true); #endif /* PAX_SEGVGUARD */ /* Acquire the sched state mutex. exit1() will release it. */ mutex_enter(p->p_lock); if (error == 0) p->p_sflag |= PS_COREDUMP; } /* No longer dumping core. */ p->p_sflag &= ~PS_WCORE; exit1(l, 0, exitsig); /* NOTREACHED */ } /* * Put process 'p' into the stopped state and optionally, notify the parent. */ void proc_stop(struct proc *p, int signo) { struct lwp *l; KASSERT(mutex_owned(p->p_lock)); /* * First off, set the stopping indicator and bring all sleeping * LWPs to a halt so they are included in p->p_nrlwps. We musn't * unlock between here and the p->p_nrlwps check below. */ p->p_sflag |= PS_STOPPING; membar_producer(); proc_stop_lwps(p); /* * If there are no LWPs available to take the signal, then we * signal the parent process immediately. Otherwise, the last * LWP to stop will take care of it. */ if (p->p_nrlwps == 0) { proc_stop_done(p, PS_NOCLDSTOP); } else { /* * Have the remaining LWPs come to a halt, and trigger * proc_stop_callout() to ensure that they do. */ LIST_FOREACH(l, &p->p_lwps, l_sibling) { sigpost(l, SIG_DFL, SA_STOP, signo); } callout_schedule(&proc_stop_ch, 1); } } /* * When stopping a process, we do not immediatly set sleeping LWPs stopped, * but wait for them to come to a halt at the kernel-user boundary. This is * to allow LWPs to release any locks that they may hold before stopping. * * Non-interruptable sleeps can be long, and there is the potential for an * LWP to begin sleeping interruptably soon after the process has been set * stopping (PS_STOPPING). These LWPs will not notice that the process is * stopping, and so complete halt of the process and the return of status * information to the parent could be delayed indefinitely. * * To handle this race, proc_stop_callout() runs once per tick while there * are stopping processes in the system. It sets LWPs that are sleeping * interruptably into the LSSTOP state. * * Note that we are not concerned about keeping all LWPs stopped while the * process is stopped: stopped LWPs can awaken briefly to handle signals. * What we do need to ensure is that all LWPs in a stopping process have * stopped at least once, so that notification can be sent to the parent * process. */ static void proc_stop_callout(void *cookie) { bool more, restart; struct proc *p; (void)cookie; do { restart = false; more = false; mutex_enter(proc_lock); PROCLIST_FOREACH(p, &allproc) { mutex_enter(p->p_lock); if ((p->p_sflag & PS_STOPPING) == 0) { mutex_exit(p->p_lock); continue; } /* Stop any LWPs sleeping interruptably. */ proc_stop_lwps(p); if (p->p_nrlwps == 0) { /* * We brought the process to a halt. * Mark it as stopped and notify the * parent. * * Note that proc_stop_done() will * drop p->p_lock briefly. * Arrange to restart and check * all processes again. */ restart = true; proc_stop_done(p, PS_NOCLDSTOP); } else more = true; mutex_exit(p->p_lock); if (restart) break; } mutex_exit(proc_lock); } while (restart); /* * If we noted processes that are stopping but still have * running LWPs, then arrange to check again in 1 tick. */ if (more) callout_schedule(&proc_stop_ch, 1); } /* * Given a process in state SSTOP, set the state back to SACTIVE and * move LSSTOP'd LWPs to LSSLEEP or make them runnable. */ void proc_unstop(struct proc *p) { struct lwp *l; int sig; KASSERT(mutex_owned(proc_lock)); KASSERT(mutex_owned(p->p_lock)); p->p_stat = SACTIVE; p->p_sflag &= ~PS_STOPPING; sig = p->p_xsig; if (!p->p_waited) p->p_pptr->p_nstopchild--; LIST_FOREACH(l, &p->p_lwps, l_sibling) { lwp_lock(l); if (l->l_stat != LSSTOP || (l->l_flag & LW_DBGSUSPEND) != 0) { lwp_unlock(l); continue; } if (l->l_wchan == NULL) { setrunnable(l); continue; } if (sig && (l->l_flag & LW_SINTR) != 0) { setrunnable(l); sig = 0; } else { l->l_stat = LSSLEEP; p->p_nrlwps++; lwp_unlock(l); } } } void proc_stoptrace(int trapno, int sysnum, const register_t args[], const register_t *ret, int error) { struct lwp *l = curlwp; struct proc *p = l->l_proc; struct sigacts *ps; sigset_t *mask; sig_t action; ksiginfo_t ksi; size_t i, sy_narg; const int signo = SIGTRAP; KASSERT((trapno == TRAP_SCE) || (trapno == TRAP_SCX)); KASSERT(p->p_pptr != initproc); KASSERT(ISSET(p->p_slflag, PSL_TRACED)); KASSERT(ISSET(p->p_slflag, PSL_SYSCALL)); sy_narg = p->p_emul->e_sysent[sysnum].sy_narg; KSI_INIT_TRAP(&ksi); ksi.ksi_lid = l->l_lid; ksi.ksi_signo = signo; ksi.ksi_code = trapno; ksi.ksi_sysnum = sysnum; if (trapno == TRAP_SCE) { ksi.ksi_retval[0] = 0; ksi.ksi_retval[1] = 0; ksi.ksi_error = 0; } else { ksi.ksi_retval[0] = ret[0]; ksi.ksi_retval[1] = ret[1]; ksi.ksi_error = error; } memset(ksi.ksi_args, 0, sizeof(ksi.ksi_args)); for (i = 0; i < sy_narg; i++) ksi.ksi_args[i] = args[i]; mutex_enter(p->p_lock); repeat: /* * If we are exiting, demise now. * * This avoids notifying tracer and deadlocking. */ if (__predict_false(ISSET(p->p_sflag, PS_WEXIT))) { mutex_exit(p->p_lock); lwp_exit(l); panic("proc_stoptrace"); /* NOTREACHED */ } /* * If there's a pending SIGKILL process it immediately. */ if (p->p_xsig == SIGKILL || sigismember(&p->p_sigpend.sp_set, SIGKILL)) { mutex_exit(p->p_lock); return; } /* * If we are no longer traced, abandon this event signal. * * This avoids killing a process after detaching the debugger. */ if (__predict_false(!ISSET(p->p_slflag, PSL_TRACED))) { mutex_exit(p->p_lock); return; } /* * The process is already stopping. */ if ((p->p_sflag & PS_STOPPING) != 0) { sigswitch_unlock_and_switch_away(l); mutex_enter(p->p_lock); goto repeat; } /* Needed for ktrace */ ps = p->p_sigacts; action = SIGACTION_PS(ps, signo).sa_handler; mask = &l->l_sigmask; p->p_xsig = signo; p->p_sigctx.ps_lwp = ksi.ksi_lid; p->p_sigctx.ps_info = ksi.ksi_info; sigswitch(0, signo, false); if (ktrpoint(KTR_PSIG)) { if (p->p_emul->e_ktrpsig) p->p_emul->e_ktrpsig(signo, action, mask, &ksi); else ktrpsig(signo, action, mask, &ksi); } } static int filt_sigattach(struct knote *kn) { struct proc *p = curproc; kn->kn_obj = p; kn->kn_flags |= EV_CLEAR; /* automatically set */ mutex_enter(p->p_lock); SLIST_INSERT_HEAD(&p->p_klist, kn, kn_selnext); mutex_exit(p->p_lock); return 0; } static void filt_sigdetach(struct knote *kn) { struct proc *p = kn->kn_obj; mutex_enter(p->p_lock); SLIST_REMOVE(&p->p_klist, kn, knote, kn_selnext); mutex_exit(p->p_lock); } /* * Signal knotes are shared with proc knotes, so we apply a mask to * the hint in order to differentiate them from process hints. This * could be avoided by using a signal-specific knote list, but probably * isn't worth the trouble. */ static int filt_signal(struct knote *kn, long hint) { if (hint & NOTE_SIGNAL) { hint &= ~NOTE_SIGNAL; if (kn->kn_id == hint) kn->kn_data++; } return (kn->kn_data != 0); } const struct filterops sig_filtops = { .f_isfd = 0, .f_attach = filt_sigattach, .f_detach = filt_sigdetach, .f_event = filt_signal, };