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NetBSD/sys/kern/kern_sig.c
jdolecek e0cc03a09b merge kqueue branch into -current 
kqueue provides a stateful and efficient event notification framework
currently supported events include socket, file, directory, fifo,
pipe, tty and device changes, and monitoring of processes and signals

kqueue is supported by all writable filesystems in NetBSD tree
(with exception of Coda) and all device drivers supporting poll(2)

based on work done by Jonathan Lemon for FreeBSD
initial NetBSD port done by Luke Mewburn and Jason Thorpe
2002-10-23 09:10:23 +00:00

1553 lines
37 KiB
C
Raw Blame History

/* $NetBSD: kern_sig.c,v 1.126 2002/10/23 09:14:20 jdolecek Exp $ */
/*
* 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. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* 4. 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
*/
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: kern_sig.c,v 1.126 2002/10/23 09:14:20 jdolecek Exp $");
#include "opt_ktrace.h"
#include "opt_compat_sunos.h"
#include "opt_compat_netbsd32.h"
#define SIGPROP /* include signal properties table */
#include <sys/param.h>
#include <sys/signalvar.h>
#include <sys/resourcevar.h>
#include <sys/namei.h>
#include <sys/vnode.h>
#include <sys/proc.h>
#include <sys/systm.h>
#include <sys/timeb.h>
#include <sys/times.h>
#include <sys/buf.h>
#include <sys/acct.h>
#include <sys/file.h>
#include <sys/kernel.h>
#include <sys/wait.h>
#include <sys/ktrace.h>
#include <sys/syslog.h>
#include <sys/stat.h>
#include <sys/core.h>
#include <sys/filedesc.h>
#include <sys/malloc.h>
#include <sys/pool.h>
#include <sys/exec.h>
#include <sys/mount.h>
#include <sys/syscallargs.h>
#include <machine/cpu.h>
#include <sys/user.h> /* for coredump */
#include <uvm/uvm_extern.h>
static void proc_stop(struct proc *p);
static int build_corename(struct proc *, char [MAXPATHLEN]);
sigset_t contsigmask, stopsigmask, sigcantmask;
struct pool sigacts_pool; /* memory pool for sigacts structures */
/*
* Can process p, with pcred pc, send the signal signum to process q?
*/
#define CANSIGNAL(p, pc, q, signum) \
((pc)->pc_ucred->cr_uid == 0 || \
(pc)->p_ruid == (q)->p_cred->p_ruid || \
(pc)->pc_ucred->cr_uid == (q)->p_cred->p_ruid || \
(pc)->p_ruid == (q)->p_ucred->cr_uid || \
(pc)->pc_ucred->cr_uid == (q)->p_ucred->cr_uid || \
((signum) == SIGCONT && (q)->p_session == (p)->p_session))
/*
* Initialize signal-related data structures.
*/
void
signal_init(void)
{
pool_init(&sigacts_pool, sizeof(struct sigacts), 0, 0, 0, "sigapl",
&pool_allocator_nointr);
}
/*
* Create an initial sigctx structure, using the same signal state
* as p. If 'share' is set, share the sigctx_proc part, otherwise just
* copy it from parent.
*/
void
sigactsinit(struct proc *np, struct proc *pp, int share)
{
struct sigacts *ps;
if (share) {
np->p_sigacts = pp->p_sigacts;
pp->p_sigacts->sa_refcnt++;
} else {
ps = pool_get(&sigacts_pool, PR_WAITOK);
if (pp)
memcpy(ps, pp->p_sigacts, sizeof(struct sigacts));
else
memset(ps, '\0', sizeof(struct sigacts));
ps->sa_refcnt = 1;
np->p_sigacts = ps;
}
}
/*
* Make this process not share its sigctx, maintaining all
* signal state.
*/
void
sigactsunshare(struct proc *p)
{
struct sigacts *oldps;
if (p->p_sigacts->sa_refcnt == 1)
return;
oldps = p->p_sigacts;
sigactsinit(p, NULL, 0);
if (--oldps->sa_refcnt == 0)
pool_put(&sigacts_pool, oldps);
}
/*
* Release a sigctx structure.
*/
void
sigactsfree(struct proc *p)
{
struct sigacts *ps;
ps = p->p_sigacts;
if (--ps->sa_refcnt > 0)
return;
pool_put(&sigacts_pool, ps);
}
int
sigaction1(struct proc *p, int signum, const struct sigaction *nsa,
struct sigaction *osa, void *tramp, int vers)
{
struct sigacts *ps;
int prop;
ps = p->p_sigacts;
if (signum <= 0 || signum >= NSIG)
return (EINVAL);
/*
* Trampoline ABI version 0 is reserved for the legacy
* kernel-provided on-stack trampoline. Conversely, if
* we are using a non-0 ABI version, we must have a
* trampoline.
*/
if ((vers != 0 && tramp == NULL) ||
(vers == 0 && tramp != NULL))
return (EINVAL);
if (osa)
*osa = SIGACTION_PS(ps, signum);
if (nsa) {
if (nsa->sa_flags & ~SA_ALLBITS)
return (EINVAL);
prop = sigprop[signum];
if (prop & SA_CANTMASK)
return (EINVAL);
(void) splsched(); /* XXXSMP */
SIGACTION_PS(ps, signum) = *nsa;
ps->sa_sigdesc[signum].sd_tramp = tramp;
ps->sa_sigdesc[signum].sd_vers = vers;
sigminusset(&sigcantmask, &SIGACTION_PS(ps, signum).sa_mask);
if ((prop & SA_NORESET) != 0)
SIGACTION_PS(ps, signum).sa_flags &= ~SA_RESETHAND;
if (signum == SIGCHLD) {
if (nsa->sa_flags & SA_NOCLDSTOP)
p->p_flag |= P_NOCLDSTOP;
else
p->p_flag &= ~P_NOCLDSTOP;
if (nsa->sa_flags & SA_NOCLDWAIT) {
/*
* Paranoia: since SA_NOCLDWAIT is implemented
* by reparenting the dying child to PID 1 (and
* trust it to reap the zombie), PID 1 itself
* is forbidden to set SA_NOCLDWAIT.
*/
if (p->p_pid == 1)
p->p_flag &= ~P_NOCLDWAIT;
else
p->p_flag |= P_NOCLDWAIT;
} else
p->p_flag &= ~P_NOCLDWAIT;
}
if ((nsa->sa_flags & SA_NODEFER) == 0)
sigaddset(&SIGACTION_PS(ps, signum).sa_mask, signum);
else
sigdelset(&SIGACTION_PS(ps, signum).sa_mask, signum);
/*
* Set bit in p_sigctx.ps_sigignore for signals that are set to
* SIG_IGN, and for signals set to SIG_DFL where the default is
* to ignore. However, don't put SIGCONT in
* p_sigctx.ps_sigignore, as we have to restart the process.
*/
if (nsa->sa_handler == SIG_IGN ||
(nsa->sa_handler == SIG_DFL && (prop & SA_IGNORE) != 0)) {
/* never to be seen again */
sigdelset(&p->p_sigctx.ps_siglist, signum);
if (signum != SIGCONT) {
/* easier in psignal */
sigaddset(&p->p_sigctx.ps_sigignore, signum);
}
sigdelset(&p->p_sigctx.ps_sigcatch, signum);
} else {
sigdelset(&p->p_sigctx.ps_sigignore, signum);
if (nsa->sa_handler == SIG_DFL)
sigdelset(&p->p_sigctx.ps_sigcatch, signum);
else
sigaddset(&p->p_sigctx.ps_sigcatch, signum);
}
(void) spl0();
}
return (0);
}
/* ARGSUSED */
int
sys___sigaction14(struct proc *p, void *v, register_t *retval)
{
struct sys___sigaction14_args /* {
syscallarg(int) signum;
syscallarg(const struct sigaction *) nsa;
syscallarg(struct sigaction *) osa;
} */ *uap = v;
struct sigaction nsa, osa;
int error;
if (SCARG(uap, nsa)) {
error = copyin(SCARG(uap, nsa), &nsa, sizeof(nsa));
if (error)
return (error);
}
error = sigaction1(p, SCARG(uap, signum),
SCARG(uap, nsa) ? &nsa : 0, SCARG(uap, osa) ? &osa : 0,
NULL, 0);
if (error)
return (error);
if (SCARG(uap, osa)) {
error = copyout(&osa, SCARG(uap, osa), sizeof(osa));
if (error)
return (error);
}
return (0);
}
/* ARGSUSED */
int
sys___sigaction_sigtramp(struct proc *p, void *v, register_t *retval)
{
struct sys___sigaction_sigtramp_args /* {
syscallarg(int) signum;
syscallarg(const struct sigaction *) nsa;
syscallarg(struct sigaction *) osa;
syscallarg(void *) tramp;
syscallarg(int) vers;
} */ *uap = v;
struct sigaction nsa, osa;
int error;
if (SCARG(uap, nsa)) {
error = copyin(SCARG(uap, nsa), &nsa, sizeof(nsa));
if (error)
return (error);
}
error = sigaction1(p, SCARG(uap, signum),
SCARG(uap, nsa) ? &nsa : 0, SCARG(uap, osa) ? &osa : 0,
SCARG(uap, tramp), SCARG(uap, vers));
if (error)
return (error);
if (SCARG(uap, osa)) {
error = copyout(&osa, SCARG(uap, osa), sizeof(osa));
if (error)
return (error);
}
return (0);
}
/*
* Initialize signal state for process 0;
* set to ignore signals that are ignored by default and disable the signal
* stack.
*/
void
siginit(struct proc *p)
{
struct sigacts *ps;
int signum, prop;
ps = p->p_sigacts;
sigemptyset(&contsigmask);
sigemptyset(&stopsigmask);
sigemptyset(&sigcantmask);
for (signum = 1; signum < NSIG; signum++) {
prop = sigprop[signum];
if (prop & SA_CONT)
sigaddset(&contsigmask, signum);
if (prop & SA_STOP)
sigaddset(&stopsigmask, signum);
if (prop & SA_CANTMASK)
sigaddset(&sigcantmask, signum);
if (prop & SA_IGNORE && signum != SIGCONT)
sigaddset(&p->p_sigctx.ps_sigignore, signum);
sigemptyset(&SIGACTION_PS(ps, signum).sa_mask);
SIGACTION_PS(ps, signum).sa_flags = SA_RESTART;
}
sigemptyset(&p->p_sigctx.ps_sigcatch);
p->p_flag &= ~P_NOCLDSTOP;
/*
* Reset stack state to the user stack.
*/
p->p_sigctx.ps_sigstk.ss_flags = SS_DISABLE;
p->p_sigctx.ps_sigstk.ss_size = 0;
p->p_sigctx.ps_sigstk.ss_sp = 0;
/* One reference. */
ps->sa_refcnt = 1;
}
/*
* Reset signals for an exec of the specified process.
*/
void
execsigs(struct proc *p)
{
struct sigacts *ps;
int signum, prop;
sigactsunshare(p);
ps = p->p_sigacts;
/*
* Reset caught signals. Held signals remain held
* through p_sigctx.ps_sigmask (unless they were caught,
* and are now ignored by default).
*/
for (signum = 1; signum < NSIG; signum++) {
if (sigismember(&p->p_sigctx.ps_sigcatch, signum)) {
prop = sigprop[signum];
if (prop & SA_IGNORE) {
if ((prop & SA_CONT) == 0)
sigaddset(&p->p_sigctx.ps_sigignore,
signum);
sigdelset(&p->p_sigctx.ps_siglist, signum);
}
SIGACTION_PS(ps, signum).sa_handler = SIG_DFL;
}
sigemptyset(&SIGACTION_PS(ps, signum).sa_mask);
SIGACTION_PS(ps, signum).sa_flags = SA_RESTART;
}
sigemptyset(&p->p_sigctx.ps_sigcatch);
p->p_flag &= ~P_NOCLDSTOP;
/*
* Reset stack state to the user stack.
*/
p->p_sigctx.ps_sigstk.ss_flags = SS_DISABLE;
p->p_sigctx.ps_sigstk.ss_size = 0;
p->p_sigctx.ps_sigstk.ss_sp = 0;
}
int
sigprocmask1(struct proc *p, int how, const sigset_t *nss, sigset_t *oss)
{
if (oss)
*oss = p->p_sigctx.ps_sigmask;
if (nss) {
(void)splsched(); /* XXXSMP */
switch (how) {
case SIG_BLOCK:
sigplusset(nss, &p->p_sigctx.ps_sigmask);
break;
case SIG_UNBLOCK:
sigminusset(nss, &p->p_sigctx.ps_sigmask);
CHECKSIGS(p);
break;
case SIG_SETMASK:
p->p_sigctx.ps_sigmask = *nss;
CHECKSIGS(p);
break;
default:
(void)spl0(); /* XXXSMP */
return (EINVAL);
}
sigminusset(&sigcantmask, &p->p_sigctx.ps_sigmask);
(void)spl0(); /* XXXSMP */
}
return (0);
}
/*
* Manipulate signal mask.
* Note that we receive new mask, not pointer,
* and return old mask as return value;
* the library stub does the rest.
*/
int
sys___sigprocmask14(struct proc *p, void *v, register_t *retval)
{
struct sys___sigprocmask14_args /* {
syscallarg(int) how;
syscallarg(const sigset_t *) set;
syscallarg(sigset_t *) oset;
} */ *uap = v;
sigset_t nss, oss;
int error;
if (SCARG(uap, set)) {
error = copyin(SCARG(uap, set), &nss, sizeof(nss));
if (error)
return (error);
}
error = sigprocmask1(p, SCARG(uap, how),
SCARG(uap, set) ? &nss : 0, SCARG(uap, oset) ? &oss : 0);
if (error)
return (error);
if (SCARG(uap, oset)) {
error = copyout(&oss, SCARG(uap, oset), sizeof(oss));
if (error)
return (error);
}
return (0);
}
void
sigpending1(struct proc *p, sigset_t *ss)
{
*ss = p->p_sigctx.ps_siglist;
sigminusset(&p->p_sigctx.ps_sigmask, ss);
}
/* ARGSUSED */
int
sys___sigpending14(struct proc *p, void *v, register_t *retval)
{
struct sys___sigpending14_args /* {
syscallarg(sigset_t *) set;
} */ *uap = v;
sigset_t ss;
sigpending1(p, &ss);
return (copyout(&ss, SCARG(uap, set), sizeof(ss)));
}
int
sigsuspend1(struct proc *p, const sigset_t *ss)
{
struct sigacts *ps;
ps = p->p_sigacts;
if (ss) {
/*
* When returning from sigpause, we want
* the old mask to be restored after the
* signal handler has finished. Thus, we
* save it here and mark the sigctx structure
* to indicate this.
*/
p->p_sigctx.ps_oldmask = p->p_sigctx.ps_sigmask;
p->p_sigctx.ps_flags |= SAS_OLDMASK;
(void) splsched(); /* XXXSMP */
p->p_sigctx.ps_sigmask = *ss;
CHECKSIGS(p);
sigminusset(&sigcantmask, &p->p_sigctx.ps_sigmask);
(void) spl0(); /* XXXSMP */
}
while (tsleep((caddr_t) ps, PPAUSE|PCATCH, "pause", 0) == 0)
/* void */;
/* always return EINTR rather than ERESTART... */
return (EINTR);
}
/*
* Suspend process until signal, providing mask to be set
* in the meantime. Note nonstandard calling convention:
* libc stub passes mask, not pointer, to save a copyin.
*/
/* ARGSUSED */
int
sys___sigsuspend14(struct proc *p, void *v, register_t *retval)
{
struct sys___sigsuspend14_args /* {
syscallarg(const sigset_t *) set;
} */ *uap = v;
sigset_t ss;
int error;
if (SCARG(uap, set)) {
error = copyin(SCARG(uap, set), &ss, sizeof(ss));
if (error)
return (error);
}
return (sigsuspend1(p, SCARG(uap, set) ? &ss : 0));
}
int
sigaltstack1(struct proc *p, const struct sigaltstack *nss,
struct sigaltstack *oss)
{
if (oss)
*oss = p->p_sigctx.ps_sigstk;
if (nss) {
if (nss->ss_flags & ~SS_ALLBITS)
return (EINVAL);
if (nss->ss_flags & SS_DISABLE) {
if (p->p_sigctx.ps_sigstk.ss_flags & SS_ONSTACK)
return (EINVAL);
} else {
if (nss->ss_size < MINSIGSTKSZ)
return (ENOMEM);
}
p->p_sigctx.ps_sigstk = *nss;
}
return (0);
}
/* ARGSUSED */
int
sys___sigaltstack14(struct proc *p, void *v, register_t *retval)
{
struct sys___sigaltstack14_args /* {
syscallarg(const struct sigaltstack *) nss;
syscallarg(struct sigaltstack *) oss;
} */ *uap = v;
struct sigaltstack nss, oss;
int error;
if (SCARG(uap, nss)) {
error = copyin(SCARG(uap, nss), &nss, sizeof(nss));
if (error)
return (error);
}
error = sigaltstack1(p,
SCARG(uap, nss) ? &nss : 0, SCARG(uap, oss) ? &oss : 0);
if (error)
return (error);
if (SCARG(uap, oss)) {
error = copyout(&oss, SCARG(uap, oss), sizeof(oss));
if (error)
return (error);
}
return (0);
}
/* ARGSUSED */
int
sys_kill(struct proc *cp, void *v, register_t *retval)
{
struct sys_kill_args /* {
syscallarg(int) pid;
syscallarg(int) signum;
} */ *uap = v;
struct proc *p;
struct pcred *pc;
pc = cp->p_cred;
if ((u_int)SCARG(uap, signum) >= NSIG)
return (EINVAL);
if (SCARG(uap, pid) > 0) {
/* kill single process */
if ((p = pfind(SCARG(uap, pid))) == NULL)
return (ESRCH);
if (!CANSIGNAL(cp, pc, p, SCARG(uap, signum)))
return (EPERM);
if (SCARG(uap, signum))
psignal(p, SCARG(uap, signum));
return (0);
}
switch (SCARG(uap, pid)) {
case -1: /* broadcast signal */
return (killpg1(cp, SCARG(uap, signum), 0, 1));
case 0: /* signal own process group */
return (killpg1(cp, SCARG(uap, signum), 0, 0));
default: /* negative explicit process group */
return (killpg1(cp, SCARG(uap, signum), -SCARG(uap, pid), 0));
}
/* NOTREACHED */
}
/*
* Common code for kill process group/broadcast kill.
* cp is calling process.
*/
int
killpg1(struct proc *cp, int signum, int pgid, int all)
{
struct proc *p;
struct pcred *pc;
struct pgrp *pgrp;
int nfound;
pc = cp->p_cred;
nfound = 0;
if (all) {
/*
* broadcast
*/
proclist_lock_read();
LIST_FOREACH(p, &allproc, p_list) {
if (p->p_pid <= 1 || p->p_flag & P_SYSTEM ||
p == cp || !CANSIGNAL(cp, pc, p, signum))
continue;
nfound++;
if (signum)
psignal(p, signum);
}
proclist_unlock_read();
} else {
if (pgid == 0)
/*
* zero pgid means send to my process group.
*/
pgrp = cp->p_pgrp;
else {
pgrp = pgfind(pgid);
if (pgrp == NULL)
return (ESRCH);
}
LIST_FOREACH(p, &pgrp->pg_members, p_pglist) {
if (p->p_pid <= 1 || p->p_flag & P_SYSTEM ||
!CANSIGNAL(cp, pc, p, signum))
continue;
nfound++;
if (signum && P_ZOMBIE(p) == 0)
psignal(p, signum);
}
}
return (nfound ? 0 : ESRCH);
}
/*
* Send a signal to a process group.
*/
void
gsignal(int pgid, int signum)
{
struct pgrp *pgrp;
if (pgid && (pgrp = pgfind(pgid)))
pgsignal(pgrp, signum, 0);
}
/*
* Send a signal to a process group. If checktty is 1,
* limit to members which have a controlling terminal.
*/
void
pgsignal(struct pgrp *pgrp, int signum, int checkctty)
{
struct proc *p;
if (pgrp)
LIST_FOREACH(p, &pgrp->pg_members, p_pglist)
if (checkctty == 0 || p->p_flag & P_CONTROLT)
psignal(p, signum);
}
/*
* Send a signal caused by a trap to the current process.
* If it will be caught immediately, deliver it with correct code.
* Otherwise, post it normally.
*/
void
trapsignal(struct proc *p, int signum, u_long code)
{
struct sigacts *ps;
ps = p->p_sigacts;
if ((p->p_flag & P_TRACED) == 0 &&
sigismember(&p->p_sigctx.ps_sigcatch, signum) &&
!sigismember(&p->p_sigctx.ps_sigmask, signum)) {
p->p_stats->p_ru.ru_nsignals++;
#ifdef KTRACE
if (KTRPOINT(p, KTR_PSIG))
ktrpsig(p, signum,
SIGACTION_PS(ps, signum).sa_handler,
&p->p_sigctx.ps_sigmask, code);
#endif
(*p->p_emul->e_sendsig)(signum, &p->p_sigctx.ps_sigmask,
code);
(void) splsched(); /* XXXSMP */
sigplusset(&SIGACTION_PS(ps, signum).sa_mask,
&p->p_sigctx.ps_sigmask);
if (SIGACTION_PS(ps, signum).sa_flags & SA_RESETHAND) {
sigdelset(&p->p_sigctx.ps_sigcatch, signum);
if (signum != SIGCONT && sigprop[signum] & SA_IGNORE)
sigaddset(&p->p_sigctx.ps_sigignore, signum);
SIGACTION_PS(ps, signum).sa_handler = SIG_DFL;
}
(void) spl0(); /* XXXSMP */
} else {
p->p_sigctx.ps_code = code; /* XXX for core dump/debugger */
p->p_sigctx.ps_sig = signum; /* XXX to verify code */
psignal(p, signum);
}
}
/*
* 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.
*
* XXXSMP: Invoked as psignal() or sched_psignal().
*/
void
psignal1(struct proc *p, int signum,
int dolock) /* XXXSMP: works, but icky */
{
int s, prop;
sig_t action;
#ifdef DIAGNOSTIC
if (signum <= 0 || signum >= NSIG)
panic("psignal signal number");
/* XXXSMP: works, but icky */
if (dolock)
SCHED_ASSERT_UNLOCKED();
else
SCHED_ASSERT_LOCKED();
#endif
/*
* Notify any interested parties in the signal.
*/
KNOTE(&p->p_klist, NOTE_SIGNAL | signum);
prop = sigprop[signum];
/*
* If proc is traced, always give parent a chance.
*/
if (p->p_flag & P_TRACED)
action = SIG_DFL;
else {
/*
* If the signal is being ignored,
* then we forget about it immediately.
* (Note: we don't set SIGCONT in p_sigctx.ps_sigignore,
* and if it is set to SIG_IGN,
* action will be SIG_DFL here.)
*/
if (sigismember(&p->p_sigctx.ps_sigignore, signum))
return;
if (sigismember(&p->p_sigctx.ps_sigmask, signum))
action = SIG_HOLD;
else if (sigismember(&p->p_sigctx.ps_sigcatch, signum))
action = SIG_CATCH;
else {
action = SIG_DFL;
if (prop & SA_KILL && p->p_nice > NZERO)
p->p_nice = NZERO;
/*
* 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_CONT)
sigminusset(&stopsigmask, &p->p_sigctx.ps_siglist);
if (prop & SA_STOP)
sigminusset(&contsigmask, &p->p_sigctx.ps_siglist);
sigaddset(&p->p_sigctx.ps_siglist, signum);
/* CHECKSIGS() is "inlined" here. */
p->p_sigctx.ps_sigcheck = 1;
/*
* Defer further processing for signals which are held,
* except that stopped processes must be continued by SIGCONT.
*/
if (action == SIG_HOLD && ((prop & SA_CONT) == 0 || p->p_stat != SSTOP))
return;
/* XXXSMP: works, but icky */
if (dolock)
SCHED_LOCK(s);
switch (p->p_stat) {
case SSLEEP:
/*
* If process is sleeping uninterruptibly
* we can't interrupt the sleep... the signal will
* be noticed when the process returns through
* trap() or syscall().
*/
if ((p->p_flag & P_SINTR) == 0)
goto out;
/*
* Process is sleeping and traced... make it runnable
* so it can discover the signal in issignal() and stop
* for the parent.
*/
if (p->p_flag & P_TRACED)
goto run;
/*
* If SIGCONT is default (or ignored) and process is
* asleep, we are finished; the process should not
* be awakened.
*/
if ((prop & SA_CONT) && action == SIG_DFL) {
sigdelset(&p->p_sigctx.ps_siglist, signum);
goto out;
}
/*
* When a sleeping process receives a stop
* signal, process immediately if possible.
*/
if ((prop & SA_STOP) && action == SIG_DFL) {
/*
* If a child holding parent blocked,
* stopping could cause deadlock.
*/
if (p->p_flag & P_PPWAIT)
goto out;
sigdelset(&p->p_sigctx.ps_siglist, signum);
p->p_xstat = signum;
if ((p->p_pptr->p_flag & P_NOCLDSTOP) == 0) {
/*
* XXXSMP: recursive call; don't lock
* the second time around.
*/
sched_psignal(p->p_pptr, SIGCHLD);
}
proc_stop(p); /* XXXSMP: recurse? */
goto out;
}
/*
* All other (caught or default) signals
* cause the process to run.
*/
goto runfast;
/*NOTREACHED*/
case SSTOP:
/*
* If traced process is already stopped,
* then no further action is necessary.
*/
if (p->p_flag & P_TRACED)
goto out;
/*
* Kill signal always sets processes running.
*/
if (signum == SIGKILL)
goto runfast;
if (prop & SA_CONT) {
/*
* If SIGCONT is default (or ignored), we continue the
* process but don't leave the signal in p_sigctx.ps_siglist, as
* it has no further action. If SIGCONT is held, we
* continue the process and leave the signal in
* p_sigctx.ps_siglist. If the process catches SIGCONT, let it
* handle the signal itself. If it isn't waiting on
* an event, then it goes back to run state.
* Otherwise, process goes back to sleep state.
*/
if (action == SIG_DFL)
sigdelset(&p->p_sigctx.ps_siglist, signum);
if (action == SIG_CATCH)
goto runfast;
if (p->p_wchan == 0)
goto run;
p->p_stat = SSLEEP;
goto out;
}
if (prop & SA_STOP) {
/*
* Already stopped, don't need to stop again.
* (If we did the shell could get confused.)
*/
sigdelset(&p->p_sigctx.ps_siglist, signum);
goto out;
}
/*
* If process is sleeping interruptibly, then simulate a
* wakeup so that when it is continued, it will be made
* runnable and can look at the signal. But don't make
* the process runnable, leave it stopped.
*/
if (p->p_wchan && p->p_flag & P_SINTR)
unsleep(p);
goto out;
#ifdef __HAVE_AST_PERPROC
case SONPROC:
case SRUN:
case SIDL:
/*
* SONPROC: We're running, notice the signal when
* we return back to userspace.
*
* SRUN, SIDL: Notice the signal when we run again
* and return to back to userspace.
*/
signotify(p);
goto out;
default:
/*
* SDEAD, SZOMB: The signal will never be noticed.
*/
goto out;
#else /* ! __HAVE_AST_PERPROC */
case SONPROC:
/*
* We're running; notice the signal.
*/
signotify(p);
goto out;
default:
/*
* SRUN, SIDL, SDEAD, SZOMB do nothing with the signal.
* It will either never be noticed, or noticed very soon.
*/
goto out;
#endif /* __HAVE_AST_PERPROC */
}
/*NOTREACHED*/
runfast:
/*
* Raise priority to at least PUSER.
*/
if (p->p_priority > PUSER)
p->p_priority = PUSER;
run:
setrunnable(p); /* XXXSMP: recurse? */
out:
/* XXXSMP: works, but icky */
if (dolock)
SCHED_UNLOCK(s);
}
static __inline int firstsig(const sigset_t *);
static __inline int
firstsig(const sigset_t *ss)
{
int sig;
sig = ffs(ss->__bits[0]);
if (sig != 0)
return (sig);
#if NSIG > 33
sig = ffs(ss->__bits[1]);
if (sig != 0)
return (sig + 32);
#endif
#if NSIG > 65
sig = ffs(ss->__bits[2]);
if (sig != 0)
return (sig + 64);
#endif
#if NSIG > 97
sig = ffs(ss->__bits[3]);
if (sig != 0)
return (sig + 96);
#endif
return (0);
}
/*
* 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 (though this can usually be done without calling issignal
* by checking the pending signal masks in the CURSIG macro.) The normal call
* sequence is
*
* while (signum = CURSIG(curproc))
* postsig(signum);
*/
int
issignal(struct proc *p)
{
int s, signum, prop;
int dolock = (p->p_flag & P_SINTR) == 0, locked = !dolock;
sigset_t ss;
for (;;) {
sigpending1(p, &ss);
if (p->p_flag & P_PPWAIT)
sigminusset(&stopsigmask, &ss);
signum = firstsig(&ss);
if (signum == 0) { /* no signal to send */
p->p_sigctx.ps_sigcheck = 0;
if (locked && dolock)
SCHED_LOCK(s);
return (0);
}
/* take the signal! */
sigdelset(&p->p_sigctx.ps_siglist, signum);
/*
* We should see pending but ignored signals
* only if P_TRACED was on when they were posted.
*/
if (sigismember(&p->p_sigctx.ps_sigignore, signum) &&
(p->p_flag & P_TRACED) == 0)
continue;
if (p->p_flag & P_TRACED && (p->p_flag & P_PPWAIT) == 0) {
/*
* If traced, always stop, and stay
* stopped until released by the debugger.
*/
p->p_xstat = signum;
if ((p->p_flag & P_FSTRACE) == 0)
psignal1(p->p_pptr, SIGCHLD, dolock);
if (dolock)
SCHED_LOCK(s);
proc_stop(p);
mi_switch(p, NULL);
SCHED_ASSERT_UNLOCKED();
if (dolock)
splx(s);
else
dolock = 1;
/*
* If we are no longer being traced, or the parent
* didn't give us a signal, look for more signals.
*/
if ((p->p_flag & P_TRACED) == 0 || p->p_xstat == 0)
continue;
/*
* If the new signal is being masked, look for other
* signals.
*/
signum = p->p_xstat;
/*
* `p->p_sigctx.ps_siglist |= mask' is done
* in setrunnable().
*/
if (sigismember(&p->p_sigctx.ps_sigmask, signum))
continue;
/* take the signal! */
sigdelset(&p->p_sigctx.ps_siglist, signum);
}
prop = sigprop[signum];
/*
* Decide whether the signal should be returned.
* Return the signal's number, or fall through
* to clear it from the pending mask.
*/
switch ((long)SIGACTION(p, signum).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("Process (pid %d) got signal %d\n",
p->p_pid, signum);
#endif
break; /* == ignore */
}
/*
* 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) {
if (p->p_flag & P_TRACED ||
(p->p_pgrp->pg_jobc == 0 &&
prop & SA_TTYSTOP))
break; /* == ignore */
p->p_xstat = signum;
if ((p->p_pptr->p_flag & P_NOCLDSTOP) == 0)
psignal1(p->p_pptr, SIGCHLD, dolock);
if (dolock)
SCHED_LOCK(s);
proc_stop(p);
mi_switch(p, NULL);
SCHED_ASSERT_UNLOCKED();
if (dolock)
splx(s);
else
dolock = 1;
break;
} else if (prop & SA_IGNORE) {
/*
* Except for SIGCONT, shouldn't get here.
* Default action is to ignore; drop it.
*/
break; /* == ignore */
} else
goto keep;
/*NOTREACHED*/
case (long)SIG_IGN:
/*
* 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_flag & P_TRACED) == 0)
printf("issignal\n");
break; /* == ignore */
default:
/*
* This signal has an action, let
* postsig() process it.
*/
goto keep;
}
}
/* NOTREACHED */
keep:
/* leave the signal for later */
sigaddset(&p->p_sigctx.ps_siglist, signum);
CHECKSIGS(p);
if (locked && dolock)
SCHED_LOCK(s);
return (signum);
}
/*
* Put the argument process into the stopped state and notify the parent
* via wakeup. Signals are handled elsewhere. The process must not be
* on the run queue.
*/
static void
proc_stop(struct proc *p)
{
SCHED_ASSERT_LOCKED();
p->p_stat = SSTOP;
p->p_flag &= ~P_WAITED;
sched_wakeup((caddr_t)p->p_pptr);
}
/*
* Take the action for the specified signal
* from the current set of pending signals.
*/
void
postsig(int signum)
{
struct proc *p;
struct sigacts *ps;
sig_t action;
u_long code;
sigset_t *returnmask;
p = curproc;
ps = p->p_sigacts;
#ifdef DIAGNOSTIC
if (signum == 0)
panic("postsig");
#endif
KERNEL_PROC_LOCK(p);
sigdelset(&p->p_sigctx.ps_siglist, signum);
action = SIGACTION_PS(ps, signum).sa_handler;
#ifdef KTRACE
if (KTRPOINT(p, KTR_PSIG))
ktrpsig(p,
signum, action, p->p_sigctx.ps_flags & SAS_OLDMASK ?
&p->p_sigctx.ps_oldmask : &p->p_sigctx.ps_sigmask, 0);
#endif
if (action == SIG_DFL) {
/*
* Default action, where the default is to kill
* the process. (Other cases were ignored above.)
*/
sigexit(p, signum);
/* NOTREACHED */
} else {
/*
* If we get here, the signal must be caught.
*/
#ifdef DIAGNOSTIC
if (action == SIG_IGN ||
sigismember(&p->p_sigctx.ps_sigmask, signum))
panic("postsig action");
#endif
/*
* Set the new mask value and also defer further
* occurences of this signal.
*
* Special case: user has done a sigpause. Here the
* current mask is not of interest, but rather the
* mask from before the sigpause is what we want
* restored after the signal processing is completed.
*/
if (p->p_sigctx.ps_flags & SAS_OLDMASK) {
returnmask = &p->p_sigctx.ps_oldmask;
p->p_sigctx.ps_flags &= ~SAS_OLDMASK;
} else
returnmask = &p->p_sigctx.ps_sigmask;
p->p_stats->p_ru.ru_nsignals++;
if (p->p_sigctx.ps_sig != signum) {
code = 0;
} else {
code = p->p_sigctx.ps_code;
p->p_sigctx.ps_code = 0;
p->p_sigctx.ps_sig = 0;
}
(*p->p_emul->e_sendsig)(signum, returnmask, code);
(void) splsched(); /* XXXSMP */
sigplusset(&SIGACTION_PS(ps, signum).sa_mask,
&p->p_sigctx.ps_sigmask);
if (SIGACTION_PS(ps, signum).sa_flags & SA_RESETHAND) {
sigdelset(&p->p_sigctx.ps_sigcatch, signum);
if (signum != SIGCONT && sigprop[signum] & SA_IGNORE)
sigaddset(&p->p_sigctx.ps_sigignore, signum);
SIGACTION_PS(ps, signum).sa_handler = SIG_DFL;
}
(void) spl0(); /* XXXSMP */
}
KERNEL_PROC_UNLOCK(p);
}
/*
* Kill the current process for stated reason.
*/
void
killproc(struct proc *p, const char *why)
{
log(LOG_ERR, "pid %d was killed: %s\n", p->p_pid, why);
uprintf("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.
*/
#if defined(DEBUG)
int kern_logsigexit = 1; /* not static to make public for sysctl */
#else
int kern_logsigexit = 0; /* not static to make public for sysctl */
#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";
void
sigexit(struct proc *p, int signum)
{
int error, exitsig;
exitsig = signum;
p->p_acflag |= AXSIG;
if (sigprop[signum] & SA_CORE) {
p->p_sigctx.ps_sig = signum;
if ((error = coredump(p)) == 0)
exitsig |= WCOREFLAG;
if (kern_logsigexit) {
/* XXX What if we ever have really large UIDs? */
int uid = p->p_cred && p->p_ucred ?
(int) p->p_ucred->cr_uid : -1;
if (error)
log(LOG_INFO, lognocoredump, p->p_pid,
p->p_comm, uid, signum, error);
else
log(LOG_INFO, logcoredump, p->p_pid,
p->p_comm, uid, signum);
}
}
exit1(p, W_EXITCODE(0, exitsig));
/* NOTREACHED */
}
/*
* Dump core, into a file named "progname.core" or "core" (depending on the
* value of shortcorename), unless the process was setuid/setgid.
*/
int
coredump(struct proc *p)
{
struct vnode *vp;
struct vmspace *vm;
struct ucred *cred;
struct nameidata nd;
struct vattr vattr;
int error, error1;
char name[MAXPATHLEN];
vm = p->p_vmspace;
cred = p->p_cred->pc_ucred;
/*
* Make sure the process has not set-id, to prevent data leaks.
*/
if (p->p_flag & P_SUGID)
return (EPERM);
/*
* Refuse to core if the data + stack + user size is larger than
* the core dump limit. XXX THIS IS WRONG, because of mapped
* data.
*/
if (USPACE + ctob(vm->vm_dsize + vm->vm_ssize) >=
p->p_rlimit[RLIMIT_CORE].rlim_cur)
return (EFBIG); /* better error code? */
/*
* The core dump will go in the current working directory. Make
* sure that the directory is still there and that the mount flags
* allow us to write core dumps there.
*/
vp = p->p_cwdi->cwdi_cdir;
if (vp->v_mount == NULL ||
(vp->v_mount->mnt_flag & MNT_NOCOREDUMP) != 0)
return (EPERM);
error = build_corename(p, name);
if (error)
return error;
NDINIT(&nd, LOOKUP, NOFOLLOW, UIO_SYSSPACE, name, p);
error = vn_open(&nd, O_CREAT | FWRITE | FNOSYMLINK, S_IRUSR | S_IWUSR);
if (error)
return (error);
vp = nd.ni_vp;
/* Don't dump to non-regular files or files with links. */
if (vp->v_type != VREG ||
VOP_GETATTR(vp, &vattr, cred, p) || vattr.va_nlink != 1) {
error = EINVAL;
goto out;
}
VATTR_NULL(&vattr);
vattr.va_size = 0;
VOP_LEASE(vp, p, cred, LEASE_WRITE);
VOP_SETATTR(vp, &vattr, cred, p);
p->p_acflag |= ACORE;
/* Now dump the actual core file. */
error = (*p->p_execsw->es_coredump)(p, vp, cred);
out:
VOP_UNLOCK(vp, 0);
error1 = vn_close(vp, FWRITE, cred, p);
if (error == 0)
error = error1;
return (error);
}
/*
* Nonexistent system call-- signal process (may want to handle it).
* Flag error in case process won't see signal immediately (blocked or ignored).
*/
/* ARGSUSED */
int
sys_nosys(struct proc *p, void *v, register_t *retval)
{
psignal(p, SIGSYS);
return (ENOSYS);
}
static int
build_corename(struct proc *p, char dst[MAXPATHLEN])
{
const char *s;
char *d, *end;
int i;
for (s = p->p_limit->pl_corename, d = dst, end = d + MAXPATHLEN;
*s != '\0'; s++) {
if (*s == '%') {
switch (*(s + 1)) {
case 'n':
i = snprintf(d, end - d, "%s", p->p_comm);
break;
case 'p':
i = snprintf(d, end - d, "%d", p->p_pid);
break;
case 'u':
i = snprintf(d, end - d, "%s",
p->p_pgrp->pg_session->s_login);
break;
case 't':
i = snprintf(d, end - d, "%ld",
p->p_stats->p_start.tv_sec);
break;
default:
goto copy;
}
d += i;
s++;
} else {
copy: *d = *s;
d++;
}
if (d >= end)
return (ENAMETOOLONG);
}
*d = '\0';
return (0);
}
/*
* Returns true if signal is ignored or masked for passed process.
*/
int
sigismasked(struct proc *p, int sig)
{
return (sigismember(&p->p_sigctx.ps_sigignore, sig) ||
sigismember(&p->p_sigctx.ps_sigmask, sig));
}
static int
filt_sigattach(struct knote *kn)
{
struct proc *p = curproc;
kn->kn_ptr.p_proc = p;
kn->kn_flags |= EV_CLEAR; /* automatically set */
SLIST_INSERT_HEAD(&p->p_klist, kn, kn_selnext);
return (0);
}
static void
filt_sigdetach(struct knote *kn)
{
struct proc *p = kn->kn_ptr.p_proc;
SLIST_REMOVE(&p->p_klist, kn, knote, kn_selnext);
}
/*
* 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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