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NetBSD/sys/kern/kern_sig.c

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/* $NetBSD: kern_sig.c,v 1.319 2013/11/22 21:04:11 christos 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 <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: kern_sig.c,v 1.319 2013/11/22 21:04:11 christos Exp $");
#include "opt_ptrace.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 <sys/param.h>
#include <sys/signalvar.h>
#include <sys/proc.h>
#include <sys/systm.h>
#include <sys/wait.h>
#include <sys/ktrace.h>
#include <sys/syslog.h>
#include <sys/filedesc.h>
#include <sys/file.h>
#include <sys/pool.h>
#include <sys/ucontext.h>
#include <sys/exec.h>
#include <sys/kauth.h>
#include <sys/acct.h>
#include <sys/callout.h>
#include <sys/atomic.h>
#include <sys/cpu.h>
#include <sys/module.h>
#include <sys/sdt.h>
#ifdef PAX_SEGVGUARD
#include <sys/pax.h>
#endif /* PAX_SEGVGUARD */
#include <uvm/uvm_extern.h>
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;
static sigset_t stopsigmask __cacheline_aligned;
sigset_t sigcantmask __cacheline_aligned;
static void ksiginfo_exechook(struct proc *, void *);
static void proc_stop_callout(void *);
static int sigchecktrace(void);
static int sigpost(struct lwp *, sig_t, int, int);
static void sigput(sigpend_t *, struct proc *, ksiginfo_t *);
static int sigunwait(struct proc *, const ksiginfo_t *);
static void sigswitch(bool, int, int);
static void sigacts_poolpage_free(struct pool *, void *);
static void *sigacts_poolpage_alloc(struct pool *, int);
void (*sendsig_sigcontext_vec)(const struct ksiginfo *, const sigset_t *);
int (*coredump_vec)(struct lwp *, const char *) =
(int (*)(struct lwp *, const char *))enosys;
/*
* DTrace SDT provider definitions
*/
SDT_PROBE_DEFINE(proc,,,signal_send,signal-send,
"struct lwp *", NULL, /* target thread */
"struct proc *", NULL, /* target process */
"int", NULL, /* signal */
NULL, NULL, NULL, NULL);
SDT_PROBE_DEFINE(proc,,,signal_discard,signal-discard,
"struct lwp *", NULL, /* target thread */
"struct proc *", NULL, /* target process */
"int", NULL, /* signal */
NULL, NULL, NULL, NULL);
SDT_PROBE_DEFINE(proc,,,signal_clear,signal-clear,
"int", NULL, /* signal */
NULL, NULL, NULL, NULL,
NULL, NULL, NULL, NULL);
SDT_PROBE_DEFINE(proc,,,signal_handle,signal-handle,
"int", NULL, /* signal */
"ksiginfo_t *", NULL,
"void (*)(void)", NULL, /* handler address */
NULL, NULL, NULL, NULL);
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;
}
/*
* 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, NULL, 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(&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_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_flags = SS_DISABLE;
l->l_sigstk.ss_size = 0;
l->l_sigstk.ss_sp = 0;
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_flags = SS_DISABLE;
l->l_sigstk.ss_size = 0;
l->l_sigstk.ss_sp = 0;
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 bool
siggetinfo(sigpend_t *sp, ksiginfo_t *out, int signo)
{
ksiginfo_t *ksi;
if (sp == NULL)
goto out;
/* Find siginfo and copy it out. */
TAILQ_FOREACH(ksi, &sp->sp_info, ksi_list) {
if (ksi->ksi_signo != signo)
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); /* XXXSMP */
return true;
}
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 false;
}
/*
* 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;
/* 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:
(void)siggetinfo(sp, out, signo);
return signo;
}
/*
* sigput:
*
* Append a new ksiginfo element to the list of pending ksiginfo's.
*/
static void
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;
KASSERT((ksi->ksi_flags & KSI_FROMPOOL) != 0);
#ifdef notyet /* XXX: QUEUING */
if (ksi->ksi_signo < SIGRTMIN)
#endif
{
TAILQ_FOREACH(kp, &sp->sp_info, ksi_list) {
if (kp->ksi_signo == ksi->ksi_signo) {
KSI_COPY(ksi, kp);
kp->ksi_flags |= KSI_QUEUED;
return;
}
}
}
ksi->ksi_flags |= KSI_QUEUED;
TAILQ_INSERT_TAIL(&sp->sp_info, ksi, ksi_list);
}
/*
* 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;
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);
mask = &l->l_sigmask;
ps = p->p_sigacts;
if ((p->p_slflag & PSL_TRACED) == 0 &&
sigismember(&p->p_sigctx.ps_sigcatch, signo) &&
!sigismember(mask, signo)) {
mutex_exit(proc_lock);
l->l_ru.ru_nsignals++;
kpsendsig(l, ksi, mask);
mutex_exit(p->p_lock);
ktrpsig(signo, SIGACTION_PS(ps, signo).sa_handler, mask, ksi);
} else {
/* XXX for core dump/debugger */
p->p_sigctx.ps_lwp = l->l_lid;
p->p_sigctx.ps_signo = ksi->ksi_signo;
p->p_sigctx.ps_code = ksi->ksi_trap;
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 xstat;
KASSERT(mutex_owned(proc_lock));
KASSERT(mutex_owned(p->p_lock));
xstat = p->p_xstat;
KSI_INIT(&ksi);
ksi.ksi_signo = SIGCHLD;
ksi.ksi_code = (xstat == SIGCONT ? CLD_CONTINUED : CLD_STOPPED);
ksi.ksi_pid = p->p_pid;
ksi.ksi_uid = kauth_cred_geteuid(p->p_cred);
ksi.ksi_status = xstat;
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,,,signal_send, l, p, sig, 0, 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.
*/
lwp_lock(l);
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.
*/
void
kpsignal2(struct proc *p, ksiginfo_t *ksi)
{
int prop, signo = ksi->ksi_signo;
struct sigacts *sa;
struct lwp *l;
ksiginfo_t *kp;
lwpid_t lid;
sig_t action;
bool toall;
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;
/*
* 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)
return;
sigput(&p->p_sigpend, p, kp);
}
} else {
/*
* If the signal was the result of a trap and is not being
* caught, then reset it to default action so that the
* process dumps core immediately.
*/
if (KSI_TRAP_P(ksi)) {
sa = p->p_sigacts;
mutex_enter(&sa->sa_mutex);
if (!sigismember(&p->p_sigctx.ps_sigcatch, signo)) {
sigdelset(&p->p_sigctx.ps_sigignore, signo);
SIGACTION(p, signo).sa_handler = SIG_DFL;
}
mutex_exit(&sa->sa_mutex);
}
/*
* 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))
return;
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)
return;
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))
return;
/*
* XXXSMP Should be allocated by the caller, we're holding locks
* here.
*/
if (kp == NULL && (kp = ksiginfo_alloc(p, ksi, PR_NOWAIT)) == NULL)
return;
/*
* 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) {
sigput(&l->l_sigpend, p, kp);
membar_producer();
(void)sigpost(l, action, prop, kp->ksi_signo);
}
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 wasn't
* collected by its parent.
*/
p->p_stat = SACTIVE;
p->p_sflag &= ~PS_STOPPING;
if (!p->p_waited) {
p->p_pptr->p_nstopchild--;
}
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 && 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);
sigput(&p->p_sigpend, p, kp);
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;
}
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);
}
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 PS_NOTIFYSTOP is set and ppsig is true.
*/
static void
proc_stop_done(struct proc *p, bool ppsig, 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++;
if ((p->p_sflag & PS_NOTIFYSTOP) != 0) {
if (ppsig) {
/* child_psignal drops p_lock briefly. */
child_psignal(p, ppmask);
}
cv_broadcast(&p->p_pptr->p_waitcv);
}
}
/*
* Stop the current process and switch away when being stopped or traced.
*/
static void
sigswitch(bool ppsig, int ppmask, int signo)
{
struct lwp *l = curlwp;
struct proc *p = l->l_proc;
int biglocks;
KASSERT(mutex_owned(p->p_lock));
KASSERT(l->l_stat == LSONPROC);
KASSERT(p->p_nrlwps > 0);
/*
* 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, 1, 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 (!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, ppsig, ppmask);
}
mutex_exit(proc_lock);
}
/*
* Unlock and switch away.
*/
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);
mutex_enter(p->p_lock);
}
/*
* 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_xstat == 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_xstat;
p->p_xstat = 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 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(true, PS_NOCLDSTOP, 0);
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;
if ((p->p_lflag & PL_PPWAIT) != 0)
sigminusset(&stopsigmask, &ss);
sigminusset(&l->l_sigmask, &ss);
if ((signo = firstsig(&ss)) == 0) {
sp = &p->p_sigpend;
ss = sp->sp_set;
if ((p->p_lflag & PL_PPWAIT) != 0)
sigminusset(&stopsigmask, &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;
}
}
}
/*
* 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 process is waiting
* for us, don't hang as we could deadlock.
*/
if ((p->p_slflag & PSL_TRACED) != 0 &&
(p->p_lflag & PL_PPWAIT) == 0 && signo != SIGKILL) {
/*
* 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_xstat = signo;
/* Emulation-specific handling of signal trace */
if (p->p_emul->e_tracesig == NULL ||
(*p->p_emul->e_tracesig)(p, signo) == 0)
sigswitch(!(p->p_slflag & PSL_FSTRACE), 0,
signo);
/* 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];
/* XXX no siginfo? */
SDT_PROBE(proc,,,signal_handle, signo, 0,
SIGACTION(p, signo).sa_handler, 0, 0);
/*
* 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 (p->p_slflag & PSL_TRACED ||
((p->p_lflag & PL_ORPHANPG) != 0 &&
prop & SA_TTYSTOP)) {
/* Ignore the signal. */
continue;
}
/* Take the signal. */
(void)sigget(sp, NULL, signo, NULL);
p->p_xstat = signo;
signo = 0;
sigswitch(true, PS_NOCLDSTOP, p->p_xstat);
} 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 (!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);
ktrpsig(signo, action, returnmask, &ksi);
mutex_enter(p->p_lock);
}
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. */
if (sendsig_sigcontext_vec == NULL) {
break;
}
(*sendsig_sigcontext_vec)(ksi, mask);
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;
p->p_sigctx.ps_code = 0;
p->p_sigctx.ps_signo = 0;
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;
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;
p->p_sigctx.ps_signo = signo;
if (docore) {
mutex_exit(p->p_lock);
if ((error = (*coredump_vec)(l, NULL)) == 0)
exitsig |= WCOREFLAG;
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);
}
/* No longer dumping core. */
p->p_sflag &= ~PS_WCORE;
exit1(l, W_EXITCODE(0, exitsig));
/* NOTREACHED */
}
/*
* Put process 'p' into the stopped state and optionally, notify the parent.
*/
void
proc_stop(struct proc *p, int notify, 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;
if (notify)
p->p_sflag |= PS_NOTIFYSTOP;
else
p->p_sflag &= ~PS_NOTIFYSTOP;
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, true, 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.
*/
if ((p->p_sflag & PS_NOTIFYSTOP) != 0) {
/*
* 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, true, 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_xstat;
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) {
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);
}
}
}
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 = {
0, filt_sigattach, filt_sigdetach, filt_signal
};
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