File: [local] / sys / kern / kern_sig.c (download)
Revision 1.1, Tue Mar 4 16:14:54 2008 UTC (16 years, 1 month ago) by nbrk
Branch point for: MAIN
Initial revision
|
/* $OpenBSD: kern_sig.c,v 1.94 2007/05/30 07:42:52 moritz Exp $ */
/* $NetBSD: kern_sig.c,v 1.54 1996/04/22 01:38:32 christos Exp $ */
/*
* Copyright (c) 1997 Theo de Raadt. All rights reserved.
* 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 8.7 (Berkeley) 4/18/94
*/
#define SIGPROP /* include signal properties table */
#include <sys/param.h>
#include <sys/signalvar.h>
#include <sys/resourcevar.h>
#include <sys/queue.h>
#include <sys/namei.h>
#include <sys/vnode.h>
#include <sys/event.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/stat.h>
#include <sys/core.h>
#include <sys/malloc.h>
#include <sys/pool.h>
#include <sys/ptrace.h>
#include <sys/sched.h>
#include <sys/mount.h>
#include <sys/syscallargs.h>
#include <machine/cpu.h>
#include <uvm/uvm_extern.h>
#include <sys/user.h> /* for coredump */
int filt_sigattach(struct knote *kn);
void filt_sigdetach(struct knote *kn);
int filt_signal(struct knote *kn, long hint);
struct filterops sig_filtops =
{ 0, filt_sigattach, filt_sigdetach, filt_signal };
void proc_stop(struct proc *p, int);
void proc_stop_sweep(void *);
struct timeout proc_stop_to;
int cansignal(struct proc *, struct pcred *, struct proc *, int);
struct pool sigacts_pool; /* memory pool for sigacts structures */
/*
* Can process p, with pcred pc, send the signal signum to process q?
*/
int
cansignal(struct proc *p, struct pcred *pc, struct proc *q, int signum)
{
if (pc->pc_ucred->cr_uid == 0)
return (1); /* root can always signal */
if (p == q)
return (1); /* process can always signal itself */
#ifdef RTHREADS
/* a thread can only be signalled from within the same process */
if (q->p_flag & P_THREAD) {
return (p->p_p == q->p_p);
}
#endif
if (signum == SIGCONT && q->p_session == p->p_session)
return (1); /* SIGCONT in session */
/*
* Using kill(), only certain signals can be sent to setugid
* child processes
*/
if (q->p_flag & P_SUGID) {
switch (signum) {
case 0:
case SIGKILL:
case SIGINT:
case SIGTERM:
case SIGALRM:
case SIGSTOP:
case SIGTTIN:
case SIGTTOU:
case SIGTSTP:
case SIGHUP:
case SIGUSR1:
case SIGUSR2:
if (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)
return (1);
}
return (0);
}
/* XXX
* because the P_SUGID test exists, this has extra tests which
* could be removed.
*/
if (pc->p_ruid == q->p_cred->p_ruid ||
pc->p_ruid == q->p_cred->p_svuid ||
pc->pc_ucred->cr_uid == q->p_cred->p_ruid ||
pc->pc_ucred->cr_uid == q->p_cred->p_svuid ||
pc->p_ruid == q->p_ucred->cr_uid ||
pc->pc_ucred->cr_uid == q->p_ucred->cr_uid)
return (1);
return (0);
}
/*
* Initialize signal-related data structures.
*/
void
signal_init(void)
{
timeout_set(&proc_stop_to, proc_stop_sweep, NULL);
pool_init(&sigacts_pool, sizeof(struct sigacts), 0, 0, 0, "sigapl",
&pool_allocator_nointr);
}
/*
* Create an initial sigacts structure, using the same signal state
* as p.
*/
struct sigacts *
sigactsinit(struct proc *p)
{
struct sigacts *ps;
ps = pool_get(&sigacts_pool, PR_WAITOK);
memcpy(ps, p->p_sigacts, sizeof(struct sigacts));
ps->ps_refcnt = 1;
return (ps);
}
/*
* Make p2 share p1's sigacts.
*/
void
sigactsshare(struct proc *p1, struct proc *p2)
{
p2->p_sigacts = p1->p_sigacts;
p1->p_sigacts->ps_refcnt++;
}
/*
* Make this process not share its sigacts, maintaining all
* signal state.
*/
void
sigactsunshare(struct proc *p)
{
struct sigacts *newps;
if (p->p_sigacts->ps_refcnt == 1)
return;
newps = sigactsinit(p);
sigactsfree(p);
p->p_sigacts = newps;
}
/*
* Release a sigacts structure.
*/
void
sigactsfree(struct proc *p)
{
struct sigacts *ps = p->p_sigacts;
if (--ps->ps_refcnt > 0)
return;
p->p_sigacts = NULL;
pool_put(&sigacts_pool, ps);
}
/* ARGSUSED */
int
sys_sigaction(struct proc *p, void *v, register_t *retval)
{
struct sys_sigaction_args /* {
syscallarg(int) signum;
syscallarg(const struct sigaction *) nsa;
syscallarg(struct sigaction *) osa;
} */ *uap = v;
struct sigaction vec;
struct sigaction *sa;
struct sigacts *ps = p->p_sigacts;
int signum;
int bit, error;
signum = SCARG(uap, signum);
if (signum <= 0 || signum >= NSIG ||
(SCARG(uap, nsa) && (signum == SIGKILL || signum == SIGSTOP)))
return (EINVAL);
sa = &vec;
if (SCARG(uap, osa)) {
sa->sa_handler = ps->ps_sigact[signum];
sa->sa_mask = ps->ps_catchmask[signum];
bit = sigmask(signum);
sa->sa_flags = 0;
if ((ps->ps_sigonstack & bit) != 0)
sa->sa_flags |= SA_ONSTACK;
if ((ps->ps_sigintr & bit) == 0)
sa->sa_flags |= SA_RESTART;
if ((ps->ps_sigreset & bit) != 0)
sa->sa_flags |= SA_RESETHAND;
if ((ps->ps_siginfo & bit) != 0)
sa->sa_flags |= SA_SIGINFO;
if (signum == SIGCHLD) {
if ((p->p_flag & P_NOCLDSTOP) != 0)
sa->sa_flags |= SA_NOCLDSTOP;
if ((p->p_flag & P_NOCLDWAIT) != 0)
sa->sa_flags |= SA_NOCLDWAIT;
}
if ((sa->sa_mask & bit) == 0)
sa->sa_flags |= SA_NODEFER;
sa->sa_mask &= ~bit;
error = copyout(sa, SCARG(uap, osa), sizeof (vec));
if (error)
return (error);
}
if (SCARG(uap, nsa)) {
error = copyin(SCARG(uap, nsa), sa, sizeof (vec));
if (error)
return (error);
setsigvec(p, signum, sa);
}
return (0);
}
void
setsigvec(struct proc *p, int signum, struct sigaction *sa)
{
struct sigacts *ps = p->p_sigacts;
int bit;
int s;
bit = sigmask(signum);
/*
* Change setting atomically.
*/
s = splhigh();
ps->ps_sigact[signum] = sa->sa_handler;
if ((sa->sa_flags & SA_NODEFER) == 0)
sa->sa_mask |= sigmask(signum);
ps->ps_catchmask[signum] = sa->sa_mask &~ sigcantmask;
if (signum == SIGCHLD) {
if (sa->sa_flags & SA_NOCLDSTOP)
atomic_setbits_int(&p->p_flag, P_NOCLDSTOP);
else
atomic_clearbits_int(&p->p_flag, P_NOCLDSTOP);
/*
* If the SA_NOCLDWAIT flag is set or the handler
* is SIG_IGN we reparent the dying child to PID 1
* (init) which will reap the zombie. Because we use
* init to do our dirty work we never set P_NOCLDWAIT
* for PID 1.
*/
if (p->p_pid != 1 && ((sa->sa_flags & SA_NOCLDWAIT) ||
sa->sa_handler == SIG_IGN))
atomic_setbits_int(&p->p_flag, P_NOCLDWAIT);
else
atomic_clearbits_int(&p->p_flag, P_NOCLDWAIT);
}
if ((sa->sa_flags & SA_RESETHAND) != 0)
ps->ps_sigreset |= bit;
else
ps->ps_sigreset &= ~bit;
if ((sa->sa_flags & SA_SIGINFO) != 0)
ps->ps_siginfo |= bit;
else
ps->ps_siginfo &= ~bit;
if ((sa->sa_flags & SA_RESTART) == 0)
ps->ps_sigintr |= bit;
else
ps->ps_sigintr &= ~bit;
if ((sa->sa_flags & SA_ONSTACK) != 0)
ps->ps_sigonstack |= bit;
else
ps->ps_sigonstack &= ~bit;
#ifdef COMPAT_SUNOS
{
extern struct emul emul_sunos;
if (p->p_emul == &emul_sunos) {
if (sa->sa_flags & SA_USERTRAMP)
ps->ps_usertramp |= bit;
else
ps->ps_usertramp &= ~bit;
}
}
#endif
/*
* Set bit in p_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_sigignore,
* as we have to restart the process.
*/
if (sa->sa_handler == SIG_IGN ||
(sigprop[signum] & SA_IGNORE && sa->sa_handler == SIG_DFL)) {
atomic_clearbits_int(&p->p_siglist, bit);
if (signum != SIGCONT)
p->p_sigignore |= bit; /* easier in psignal */
p->p_sigcatch &= ~bit;
} else {
p->p_sigignore &= ~bit;
if (sa->sa_handler == SIG_DFL)
p->p_sigcatch &= ~bit;
else
p->p_sigcatch |= bit;
}
splx(s);
}
/*
* Initialize signal state for process 0;
* set to ignore signals that are ignored by default.
*/
void
siginit(struct proc *p)
{
int i;
for (i = 0; i < NSIG; i++)
if (sigprop[i] & SA_IGNORE && i != SIGCONT)
p->p_sigignore |= sigmask(i);
}
/*
* Reset signals for an exec of the specified process.
*/
void
execsigs(struct proc *p)
{
struct sigacts *ps;
int nc, mask;
sigactsunshare(p);
ps = p->p_sigacts;
/*
* Reset caught signals. Held signals remain held
* through p_sigmask (unless they were caught,
* and are now ignored by default).
*/
while (p->p_sigcatch) {
nc = ffs((long)p->p_sigcatch);
mask = sigmask(nc);
p->p_sigcatch &= ~mask;
if (sigprop[nc] & SA_IGNORE) {
if (nc != SIGCONT)
p->p_sigignore |= mask;
atomic_clearbits_int(&p->p_siglist, mask);
}
ps->ps_sigact[nc] = SIG_DFL;
}
/*
* Reset stack state to the user stack.
* Clear set of signals caught on the signal stack.
*/
ps->ps_sigstk.ss_flags = SS_DISABLE;
ps->ps_sigstk.ss_size = 0;
ps->ps_sigstk.ss_sp = 0;
ps->ps_flags = 0;
atomic_clearbits_int(&p->p_flag, P_NOCLDWAIT);
if (ps->ps_sigact[SIGCHLD] == SIG_IGN)
ps->ps_sigact[SIGCHLD] = SIG_DFL;
}
/*
* 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_sigprocmask(struct proc *p, void *v, register_t *retval)
{
struct sys_sigprocmask_args /* {
syscallarg(int) how;
syscallarg(sigset_t) mask;
} */ *uap = v;
int error = 0;
int s;
*retval = p->p_sigmask;
s = splhigh();
switch (SCARG(uap, how)) {
case SIG_BLOCK:
p->p_sigmask |= SCARG(uap, mask) &~ sigcantmask;
break;
case SIG_UNBLOCK:
p->p_sigmask &= ~SCARG(uap, mask);
break;
case SIG_SETMASK:
p->p_sigmask = SCARG(uap, mask) &~ sigcantmask;
break;
default:
error = EINVAL;
break;
}
splx(s);
return (error);
}
/* ARGSUSED */
int
sys_sigpending(struct proc *p, void *v, register_t *retval)
{
*retval = p->p_siglist;
return (0);
}
/*
* 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_sigsuspend(struct proc *p, void *v, register_t *retval)
{
struct sys_sigsuspend_args /* {
syscallarg(int) mask;
} */ *uap = v;
struct sigacts *ps = p->p_sigacts;
/*
* 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 sigacts structure
* to indicate this.
*/
ps->ps_oldmask = p->p_sigmask;
ps->ps_flags |= SAS_OLDMASK;
p->p_sigmask = SCARG(uap, mask) &~ sigcantmask;
while (tsleep(ps, PPAUSE|PCATCH, "pause", 0) == 0)
/* void */;
/* always return EINTR rather than ERESTART... */
return (EINTR);
}
/* ARGSUSED */
int
sys_osigaltstack(struct proc *p, void *v, register_t *retval)
{
struct sys_osigaltstack_args /* {
syscallarg(const struct osigaltstack *) nss;
syscallarg(struct osigaltstack *) oss;
} */ *uap = v;
struct sigacts *psp;
struct osigaltstack ss;
int error;
psp = p->p_sigacts;
if ((psp->ps_flags & SAS_ALTSTACK) == 0)
psp->ps_sigstk.ss_flags |= SS_DISABLE;
if (SCARG(uap, oss)) {
ss.ss_sp = psp->ps_sigstk.ss_sp;
ss.ss_size = psp->ps_sigstk.ss_size;
ss.ss_flags = psp->ps_sigstk.ss_flags;
if ((error = copyout(&ss, SCARG(uap, oss), sizeof(ss))))
return (error);
}
if (SCARG(uap, nss) == NULL)
return (0);
error = copyin(SCARG(uap, nss), &ss, sizeof(ss));
if (error)
return (error);
if (ss.ss_flags & SS_DISABLE) {
if (psp->ps_sigstk.ss_flags & SS_ONSTACK)
return (EINVAL);
psp->ps_flags &= ~SAS_ALTSTACK;
psp->ps_sigstk.ss_flags = ss.ss_flags;
return (0);
}
if (ss.ss_size < MINSIGSTKSZ)
return (ENOMEM);
psp->ps_flags |= SAS_ALTSTACK;
psp->ps_sigstk.ss_sp = ss.ss_sp;
psp->ps_sigstk.ss_size = ss.ss_size;
psp->ps_sigstk.ss_flags = ss.ss_flags;
return (0);
}
int
sys_sigaltstack(struct proc *p, void *v, register_t *retval)
{
struct sys_sigaltstack_args /* {
syscallarg(const struct sigaltstack *) nss;
syscallarg(struct sigaltstack *) oss;
} */ *uap = v;
struct sigacts *psp;
struct sigaltstack ss;
int error;
psp = p->p_sigacts;
if ((psp->ps_flags & SAS_ALTSTACK) == 0)
psp->ps_sigstk.ss_flags |= SS_DISABLE;
if (SCARG(uap, oss) && (error = copyout(&psp->ps_sigstk,
SCARG(uap, oss), sizeof(struct sigaltstack))))
return (error);
if (SCARG(uap, nss) == NULL)
return (0);
error = copyin(SCARG(uap, nss), &ss, sizeof(ss));
if (error)
return (error);
if (ss.ss_flags & SS_DISABLE) {
if (psp->ps_sigstk.ss_flags & SS_ONSTACK)
return (EINVAL);
psp->ps_flags &= ~SAS_ALTSTACK;
psp->ps_sigstk.ss_flags = ss.ss_flags;
return (0);
}
if (ss.ss_size < MINSIGSTKSZ)
return (ENOMEM);
psp->ps_flags |= SAS_ALTSTACK;
psp->ps_sigstk = ss;
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 = 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 = cp->p_cred;
struct pgrp *pgrp;
int nfound = 0;
if (all)
/*
* broadcast
*/
for (p = LIST_FIRST(&allproc); p; p = LIST_NEXT(p, 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);
}
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);
}
#define CANDELIVER(uid, euid, p) \
(euid == 0 || \
(uid) == (p)->p_cred->p_ruid || \
(uid) == (p)->p_cred->p_svuid || \
(uid) == (p)->p_ucred->cr_uid || \
(euid) == (p)->p_cred->p_ruid || \
(euid) == (p)->p_cred->p_svuid || \
(euid) == (p)->p_ucred->cr_uid)
/*
* Deliver signum to pgid, but first check uid/euid against each
* process and see if it is permitted.
*/
void
csignal(pid_t pgid, int signum, uid_t uid, uid_t euid)
{
struct pgrp *pgrp;
struct proc *p;
if (pgid == 0)
return;
if (pgid < 0) {
pgid = -pgid;
if ((pgrp = pgfind(pgid)) == NULL)
return;
LIST_FOREACH(p, &pgrp->pg_members, p_pglist)
if (CANDELIVER(uid, euid, p))
psignal(p, signum);
} else {
if ((p = pfind(pgid)) == NULL)
return;
if (CANDELIVER(uid, euid, p))
psignal(p, signum);
}
}
/*
* 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) &&
(p->p_flag & P_THREAD) == 0)
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, int type,
union sigval sigval)
{
struct sigacts *ps = p->p_sigacts;
int mask;
mask = sigmask(signum);
if ((p->p_flag & P_TRACED) == 0 && (p->p_sigcatch & mask) != 0 &&
(p->p_sigmask & mask) == 0) {
#ifdef KTRACE
if (KTRPOINT(p, KTR_PSIG)) {
siginfo_t si;
initsiginfo(&si, signum, code, type, sigval);
ktrpsig(p, signum, ps->ps_sigact[signum],
p->p_sigmask, type, &si);
}
#endif
p->p_stats->p_ru.ru_nsignals++;
(*p->p_emul->e_sendsig)(ps->ps_sigact[signum], signum,
p->p_sigmask, code, type, sigval);
p->p_sigmask |= ps->ps_catchmask[signum];
if ((ps->ps_sigreset & mask) != 0) {
p->p_sigcatch &= ~mask;
if (signum != SIGCONT && sigprop[signum] & SA_IGNORE)
p->p_sigignore |= mask;
ps->ps_sigact[signum] = SIG_DFL;
}
} else {
ps->ps_sig = signum;
ps->ps_code = code; /* XXX for core dump/debugger */
ps->ps_type = type;
ps->ps_sigval = sigval;
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.
*/
void
psignal(struct proc *p, int signum)
{
int s, prop;
sig_t action;
int mask;
#ifdef RTHREADS
struct proc *q;
#endif
int wakeparent = 0;
#ifdef DIAGNOSTIC
if ((u_int)signum >= NSIG || signum == 0)
panic("psignal signal number");
#endif
/* Ignore signal if we are exiting */
if (p->p_flag & P_WEXIT)
return;
#ifdef RTHREADS
TAILQ_FOREACH(q, &p->p_p->ps_threads, p_thr_link) {
if (q == p)
continue;
if (q->p_sigdivert & (1 << signum)) {
q->p_sigdivert = 0;
psignal(q, signum);
return;
}
}
#endif
KNOTE(&p->p_klist, NOTE_SIGNAL | signum);
mask = sigmask(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_sigignore,
* and if it is set to SIG_IGN,
* action will be SIG_DFL here.)
*/
if (p->p_sigignore & mask)
return;
if (p->p_sigmask & mask)
action = SIG_HOLD;
else if (p->p_sigcatch & mask)
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) {
#ifdef RTHREADS
TAILQ_FOREACH(q, &p->p_p->ps_threads, p_thr_link) {
if (q != p)
psignal(q, signum);
}
#endif
atomic_clearbits_int(&p->p_siglist, stopsigmask);
}
if (prop & SA_STOP) {
#ifdef RTHREADS
TAILQ_FOREACH(q, &p->p_p->ps_threads, p_thr_link) {
if (q != p)
psignal(q, signum);
}
#endif
atomic_clearbits_int(&p->p_siglist, contsigmask);
atomic_clearbits_int(&p->p_flag, P_CONTINUED);
}
atomic_setbits_int(&p->p_siglist, mask);
/*
* 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;
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) {
atomic_clearbits_int(&p->p_siglist, mask);
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;
atomic_clearbits_int(&p->p_siglist, mask);
p->p_xstat = signum;
proc_stop(p, 0);
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_siglist, as
* it has no further action. If SIGCONT is held, we
* continue the process and leave the signal in
* p_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.
*/
atomic_setbits_int(&p->p_flag, P_CONTINUED);
wakeparent = 1;
if (action == SIG_DFL)
atomic_clearbits_int(&p->p_siglist, mask);
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.)
*/
atomic_clearbits_int(&p->p_siglist, mask);
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;
case SONPROC:
signotify(p);
/* FALLTHROUGH */
default:
/*
* SRUN, SIDL, SZOMB do nothing with the signal,
* other than kicking ourselves if we are running.
* It will either never be noticed, or noticed very soon.
*/
goto out;
}
/*NOTREACHED*/
runfast:
/*
* Raise priority to at least PUSER.
*/
if (p->p_priority > PUSER)
p->p_priority = PUSER;
run:
setrunnable(p);
out:
SCHED_UNLOCK(s);
if (wakeparent)
wakeup(p->p_pptr);
}
/*
* 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 signum, mask, prop;
int dolock = (p->p_flag & P_SINTR) == 0;
int s;
for (;;) {
mask = p->p_siglist & ~p->p_sigmask;
if (p->p_flag & P_PPWAIT)
mask &= ~stopsigmask;
if (mask == 0) /* no signal to send */
return (0);
signum = ffs((long)mask);
mask = sigmask(signum);
atomic_clearbits_int(&p->p_siglist, mask);
/*
* We should see pending but ignored signals
* only if P_TRACED was on when they were posted.
*/
if (mask & p->p_sigignore && (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 (dolock)
SCHED_LOCK(s);
proc_stop(p, 1);
if (dolock)
SCHED_UNLOCK(s);
/*
* 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;
mask = sigmask(signum);
if ((p->p_sigmask & mask) != 0)
continue;
/* take the signal! */
atomic_clearbits_int(&p->p_siglist, mask);
}
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)p->p_sigacts->ps_sigact[signum]) {
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 (dolock)
SCHED_LOCK(s);
proc_stop(p, 1);
if (dolock)
SCHED_UNLOCK(s);
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:
atomic_setbits_int(&p->p_siglist, mask); /*leave the signal for later */
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.
*/
void
proc_stop(struct proc *p, int sw)
{
#ifdef __HAVE_GENERIC_SOFT_INTERRUPTS
extern void *softclock_si;
#endif
#ifdef MULTIPROCESSOR
SCHED_ASSERT_LOCKED();
#endif
p->p_stat = SSTOP;
atomic_clearbits_int(&p->p_flag, P_WAITED);
atomic_setbits_int(&p->p_flag, P_STOPPED);
if (!timeout_pending(&proc_stop_to)) {
timeout_add(&proc_stop_to, 0);
/*
* We need this soft interrupt to be handled fast.
* Extra calls to softclock don't hurt.
*/
#ifdef __HAVE_GENERIC_SOFT_INTERRUPTS
softintr_schedule(softclock_si);
#else
setsoftclock();
#endif
}
if (sw)
mi_switch();
}
/*
* Called from a timeout to send signals to the parents of stopped processes.
* We can't do this in proc_stop because it's called with nasty locks held
* and we would need recursive scheduler lock to deal with that.
*/
void
proc_stop_sweep(void *v)
{
struct proc *p;
LIST_FOREACH(p, &allproc, p_list) {
if ((p->p_flag & P_STOPPED) == 0)
continue;
atomic_clearbits_int(&p->p_flag, P_STOPPED);
if ((p->p_pptr->p_flag & P_NOCLDSTOP) == 0)
psignal(p->p_pptr, SIGCHLD);
wakeup(p->p_pptr);
}
}
/*
* Take the action for the specified signal
* from the current set of pending signals.
*/
void
postsig(int signum)
{
struct proc *p = curproc;
struct sigacts *ps = p->p_sigacts;
sig_t action;
u_long code;
int mask, returnmask;
union sigval sigval;
int s, type;
#ifdef DIAGNOSTIC
if (signum == 0)
panic("postsig");
#endif
KERNEL_PROC_LOCK(p);
mask = sigmask(signum);
atomic_clearbits_int(&p->p_siglist, mask);
action = ps->ps_sigact[signum];
sigval.sival_ptr = 0;
type = SI_USER;
if (ps->ps_sig != signum) {
code = 0;
type = SI_USER;
sigval.sival_ptr = 0;
} else {
code = ps->ps_code;
type = ps->ps_type;
sigval = ps->ps_sigval;
}
#ifdef KTRACE
if (KTRPOINT(p, KTR_PSIG)) {
siginfo_t si;
initsiginfo(&si, signum, code, type, sigval);
ktrpsig(p, signum, action, ps->ps_flags & SAS_OLDMASK ?
ps->ps_oldmask : p->p_sigmask, type, &si);
}
#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 || (p->p_sigmask & mask))
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.
*/
#ifdef MULTIPROCESSOR
s = splsched();
#else
s = splhigh();
#endif
if (ps->ps_flags & SAS_OLDMASK) {
returnmask = ps->ps_oldmask;
ps->ps_flags &= ~SAS_OLDMASK;
} else
returnmask = p->p_sigmask;
p->p_sigmask |= ps->ps_catchmask[signum];
if ((ps->ps_sigreset & mask) != 0) {
p->p_sigcatch &= ~mask;
if (signum != SIGCONT && sigprop[signum] & SA_IGNORE)
p->p_sigignore |= mask;
ps->ps_sigact[signum] = SIG_DFL;
}
splx(s);
p->p_stats->p_ru.ru_nsignals++;
if (ps->ps_sig == signum) {
ps->ps_sig = 0;
ps->ps_code = 0;
ps->ps_type = SI_USER;
ps->ps_sigval.sival_ptr = NULL;
}
(*p->p_emul->e_sendsig)(action, signum, returnmask, code,
type, sigval);
}
KERNEL_PROC_UNLOCK(p);
}
/*
* 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 proc *p, int signum)
{
/* Mark process as going away */
atomic_setbits_int(&p->p_flag, P_WEXIT);
p->p_acflag |= AXSIG;
if (sigprop[signum] & SA_CORE) {
p->p_sigacts->ps_sig = signum;
if (coredump(p) == 0)
signum |= WCOREFLAG;
}
exit1(p, W_EXITCODE(0, signum), EXIT_NORMAL);
/* NOTREACHED */
}
int nosuidcoredump = 1;
/*
* Dump core, into a file named "progname.core", unless the process was
* setuid/setgid.
*/
int
coredump(struct proc *p)
{
struct vnode *vp;
struct ucred *cred = p->p_ucred;
struct vmspace *vm = p->p_vmspace;
struct nameidata nd;
struct vattr vattr;
int error, error1, len;
char name[sizeof("/var/crash/") + MAXCOMLEN + sizeof(".core")];
char *dir = "";
struct core core;
/*
* Don't dump if not root and the process has used set user or
* group privileges, unless the nosuidcoredump sysctl is set to 2,
* in which case dumps are put into /var/crash/.
*/
if (((p->p_flag & P_SUGID) && (error = suser(p, 0))) ||
((p->p_flag & P_SUGID) && nosuidcoredump)) {
if (nosuidcoredump == 2)
dir = "/var/crash/";
else
return (EPERM);
}
/* Don't dump if will exceed file size limit. */
if (USPACE + ctob(vm->vm_dsize + vm->vm_ssize) >=
p->p_rlimit[RLIMIT_CORE].rlim_cur)
return (EFBIG);
len = snprintf(name, sizeof(name), "%s%s.core", dir, p->p_comm);
if (len >= sizeof(name))
return (EACCES);
/*
* ... but actually write it as UID
*/
cred = crdup(cred);
cred->cr_uid = p->p_cred->p_ruid;
cred->cr_gid = p->p_cred->p_rgid;
NDINIT(&nd, LOOKUP, NOFOLLOW, UIO_SYSSPACE, name, p);
error = vn_open(&nd, O_CREAT | FWRITE | O_NOFOLLOW, S_IRUSR | S_IWUSR);
if (error) {
crfree(cred);
return (error);
}
/*
* Don't dump to non-regular files, files with links, or files
* owned by someone else.
*/
vp = nd.ni_vp;
if ((error = VOP_GETATTR(vp, &vattr, cred, p)) != 0)
goto out;
/* Don't dump to non-regular files or files with links. */
if (vp->v_type != VREG || vattr.va_nlink != 1 ||
vattr.va_mode & ((VREAD | VWRITE) >> 3 | (VREAD | VWRITE) >> 6)) {
error = EACCES;
goto out;
}
VATTR_NULL(&vattr);
vattr.va_size = 0;
VOP_SETATTR(vp, &vattr, cred, p);
p->p_acflag |= ACORE;
bcopy(p, &p->p_addr->u_kproc.kp_proc, sizeof(struct proc));
fill_eproc(p, &p->p_addr->u_kproc.kp_eproc);
core.c_midmag = 0;
strlcpy(core.c_name, p->p_comm, sizeof(core.c_name));
core.c_nseg = 0;
core.c_signo = p->p_sigacts->ps_sig;
core.c_ucode = p->p_sigacts->ps_code;
core.c_cpusize = 0;
core.c_tsize = (u_long)ctob(vm->vm_tsize);
core.c_dsize = (u_long)ctob(vm->vm_dsize);
core.c_ssize = (u_long)round_page(ctob(vm->vm_ssize));
error = cpu_coredump(p, vp, cred, &core);
if (error)
goto out;
/*
* uvm_coredump() spits out all appropriate segments.
* All that's left to do is to write the core header.
*/
error = uvm_coredump(p, vp, cred, &core);
if (error)
goto out;
error = vn_rdwr(UIO_WRITE, vp, (caddr_t)&core,
(int)core.c_hdrsize, (off_t)0,
UIO_SYSSPACE, IO_NODELOCKED|IO_UNIT, cred, NULL, p);
out:
VOP_UNLOCK(vp, 0, p);
error1 = vn_close(vp, FWRITE, cred, p);
crfree(cred);
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);
}
#ifdef RTHREADS
int
sys_thrsigdivert(struct proc *p, void *v, register_t *retval)
{
struct sys_thrsigdivert_args *uap = v;
p->p_sigdivert = SCARG(uap, sigmask);
return (0);
}
#endif
void
initsiginfo(siginfo_t *si, int sig, u_long code, int type, union sigval val)
{
bzero(si, sizeof *si);
si->si_signo = sig;
si->si_code = type;
if (type == SI_USER) {
si->si_value = val;
} else {
switch (sig) {
case SIGSEGV:
case SIGILL:
case SIGBUS:
case SIGFPE:
si->si_addr = val.sival_ptr;
si->si_trapno = code;
break;
case SIGXFSZ:
break;
}
}
}
int
filt_sigattach(struct knote *kn)
{
struct proc *p = curproc;
kn->kn_ptr.p_proc = p;
kn->kn_flags |= EV_CLEAR; /* automatically set */
/* XXX lock the proc here while adding to the list? */
SLIST_INSERT_HEAD(&p->p_klist, kn, kn_selnext);
return (0);
}
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.
*/
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);
}
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