kern_sig.c

早期freebsd实现

/*
 * 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	8.7 (Berkeley) 4/18/94
 */

#define	SIGPROP		/* include signal properties table */
#include <sys/param.h>
#include <sys/signalvar.h>
#include <sys/resourcevar.h>
#include <sys/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 <machine/cpu.h>

#include <vm/vm.h>
#include <sys/user.h>		/* for coredump */

/*
 * 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))

struct sigaction_args {
	int	signum;
	struct	sigaction *nsa;
	struct	sigaction *osa;
};
/* ARGSUSED */
sigaction(p, uap, retval)
	struct proc *p;
	register struct sigaction_args *uap;
	int *retval;
{
	struct sigaction vec;
	register struct sigaction *sa;
	register struct sigacts *ps = p->p_sigacts;
	register int signum;
	int bit, error;

	signum = uap->signum;
	if (signum <= 0 || signum >= NSIG ||
	    signum == SIGKILL || signum == SIGSTOP)
		return (EINVAL);
	sa = &vec;
	if (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 (p->p_flag & P_NOCLDSTOP)
			sa->sa_flags |= SA_NOCLDSTOP;
		if (error = copyout((caddr_t)sa, (caddr_t)uap->osa,
		    sizeof (vec)))
			return (error);
	}
	if (uap->nsa) {
		if (error = copyin((caddr_t)uap->nsa, (caddr_t)sa,
		    sizeof (vec)))
			return (error);
		setsigvec(p, signum, sa);
	}
	return (0);
}

setsigvec(p, signum, sa)
	register struct proc *p;
	int signum;
	register struct sigaction *sa;
{
	register struct sigacts *ps = p->p_sigacts;
	register int bit;

	bit = sigmask(signum);
	/*
	 * Change setting atomically.
	 */
	(void) splhigh();
	ps->ps_sigact[signum] = sa->sa_handler;
	ps->ps_catchmask[signum] = sa->sa_mask &~ sigcantmask;
	if ((sa->sa_flags & SA_RESTART) == 0)
		ps->ps_sigintr |= bit;
	else
		ps->ps_sigintr &= ~bit;
	if (sa->sa_flags & SA_ONSTACK)
		ps->ps_sigonstack |= bit;
	else
		ps->ps_sigonstack &= ~bit;
#ifdef COMPAT_SUNOS
	if (sa->sa_flags & SA_USERTRAMP)
		ps->ps_usertramp |= bit;
	else
		ps->ps_usertramp &= ~bit;
#endif
	if (signum == SIGCHLD) {
		if (sa->sa_flags & SA_NOCLDSTOP)
			p->p_flag |= P_NOCLDSTOP;
		else
			p->p_flag &= ~P_NOCLDSTOP;
	}
	/*
	 * 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)) {
		p->p_siglist &= ~bit;		/* never to be seen again */
		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;
	}
	(void) spl0();
}

/*
 * Initialize signal state for process 0;
 * set to ignore signals that are ignored by default.
 */
void
siginit(p)
	struct proc *p;
{
	register 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(p)
	register struct proc *p;
{
	register struct sigacts *ps = p->p_sigacts;
	register int nc, mask;

	/*
	 * 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;
			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 = SA_DISABLE;
	ps->ps_sigstk.ss_size = 0;
	ps->ps_sigstk.ss_base = 0;
	ps->ps_flags = 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.
 */
struct sigprocmask_args {
	int	how;
	sigset_t mask;
};
sigprocmask(p, uap, retval)
	register struct proc *p;
	struct sigprocmask_args *uap;
	int *retval;
{
	int error = 0;

	*retval = p->p_sigmask;
	(void) splhigh();

	switch (uap->how) {
	case SIG_BLOCK:
		p->p_sigmask |= uap->mask &~ sigcantmask;
		break;

	case SIG_UNBLOCK:
		p->p_sigmask &= ~uap->mask;
		break;

	case SIG_SETMASK:
		p->p_sigmask = uap->mask &~ sigcantmask;
		break;
	
	default:
		error = EINVAL;
		break;
	}
	(void) spl0();
	return (error);
}

struct sigpending_args {
	int	dummy;
};
/* ARGSUSED */
sigpending(p, uap, retval)
	struct proc *p;
	struct sigpending_args *uap;
	int *retval;
{

	*retval = p->p_siglist;
	return (0);
}

#if defined(COMPAT_43) || defined(COMPAT_SUNOS)
/*
 * Generalized interface signal handler, 4.3-compatible.
 */
struct osigvec_args {
	int	signum;
	struct	sigvec *nsv;
	struct	sigvec *osv;
};
/* ARGSUSED */
osigvec(p, uap, retval)
	struct proc *p;
	register struct osigvec_args *uap;
	int *retval;
{
	struct sigvec vec;
	register struct sigacts *ps = p->p_sigacts;
	register struct sigvec *sv;
	register int signum;
	int bit, error;

	signum = uap->signum;
	if (signum <= 0 || signum >= NSIG ||
	    signum == SIGKILL || signum == SIGSTOP)
		return (EINVAL);
	sv = &vec;
	if (uap->osv) {
		*(sig_t *)&sv->sv_handler = ps->ps_sigact[signum];
		sv->sv_mask = ps->ps_catchmask[signum];
		bit = sigmask(signum);
		sv->sv_flags = 0;
		if ((ps->ps_sigonstack & bit) != 0)
			sv->sv_flags |= SV_ONSTACK;
		if ((ps->ps_sigintr & bit) != 0)
			sv->sv_flags |= SV_INTERRUPT;
#ifndef COMPAT_SUNOS
		if (p->p_flag & P_NOCLDSTOP)
			sv->sv_flags |= SA_NOCLDSTOP;
#endif
		if (error = copyout((caddr_t)sv, (caddr_t)uap->osv,
		    sizeof (vec)))
			return (error);
	}
	if (uap->nsv) {
		if (error = copyin((caddr_t)uap->nsv, (caddr_t)sv,
		    sizeof (vec)))
			return (error);
#ifdef COMPAT_SUNOS
		/*
		 * SunOS uses this bit (4, aka SA_DISABLE) as SV_RESETHAND,
		 * `reset to SIG_DFL on delivery'. We have no such option
		 * now or ever!
		 */
		if (sv->sv_flags & SA_DISABLE)
			return (EINVAL);
		sv->sv_flags |= SA_USERTRAMP;
#endif
		sv->sv_flags ^= SA_RESTART;	/* opposite of SV_INTERRUPT */
		setsigvec(p, signum, (struct sigaction *)sv);
	}
	return (0);
}

struct osigblock_args {
	int	mask;
};
osigblock(p, uap, retval)
	register struct proc *p;
	struct osigblock_args *uap;
	int *retval;
{

	(void) splhigh();
	*retval = p->p_sigmask;
	p->p_sigmask |= uap->mask &~ sigcantmask;
	(void) spl0();
	return (0);
}

struct osigsetmask_args {
	int	mask;
};
osigsetmask(p, uap, retval)
	struct proc *p;
	struct osigsetmask_args *uap;
	int *retval;
{

	(void) splhigh();
	*retval = p->p_sigmask;
	p->p_sigmask = uap->mask &~ sigcantmask;
	(void) spl0();
	return (0);
}
#endif /* COMPAT_43 || COMPAT_SUNOS */

/*
 * 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.
 */
struct sigsuspend_args {
	sigset_t mask;
};
/* ARGSUSED */
sigsuspend(p, uap, retval)
	register struct proc *p;
	struct sigsuspend_args *uap;
	int *retval;
{
	register 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 = uap->mask &~ sigcantmask;
	while (tsleep((caddr_t) ps, PPAUSE|PCATCH, "pause", 0) == 0)
		/* void */;
	/* always return EINTR rather than ERESTART... */
	return (EINTR);
}

#if defined(COMPAT_43) || defined(COMPAT_SUNOS)
struct osigstack_args {
	struct	sigstack *nss;
	struct	sigstack *oss;
};
/* ARGSUSED */
osigstack(p, uap, retval)
	struct proc *p;
	register struct osigstack_args *uap;
	int *retval;
{
	struct sigstack ss;
	struct sigacts *psp;
	int error = 0;

	psp = p->p_sigacts;
	ss.ss_sp = psp->ps_sigstk.ss_base;
	ss.ss_onstack = psp->ps_sigstk.ss_flags & SA_ONSTACK;
	if (uap->oss && (error = copyout((caddr_t)&ss, (caddr_t)uap->oss,
	    sizeof (struct sigstack))))
		return (error);
	if (uap->nss && (error = copyin((caddr_t)uap->nss, (caddr_t)&ss,
	    sizeof (ss))) == 0) {
		psp->ps_sigstk.ss_base = ss.ss_sp;
		psp->ps_sigstk.ss_size = 0;
		psp->ps_sigstk.ss_flags |= ss.ss_onstack & SA_ONSTACK;
		psp->ps_flags |= SAS_ALTSTACK;
	}
	return (error);
}
#endif /* COMPAT_43 || COMPAT_SUNOS */

struct sigaltstack_args {
	struct	sigaltstack *nss;
	struct	sigaltstack *oss;
};
/* ARGSUSED */
sigaltstack(p, uap, retval)
	struct proc *p;
	register struct sigaltstack_args *uap;
	int *retval;
{
	struct sigacts *psp;
	struct sigaltstack ss;
	int error;

	psp = p->p_sigacts;
	if ((psp->ps_flags & SAS_ALTSTACK) == 0)
		psp->ps_sigstk.ss_flags |= SA_DISABLE;
	if (uap->oss && (error = copyout((caddr_t)&psp->ps_sigstk,
	    (caddr_t)uap->oss, sizeof (struct sigaltstack))))
		return (error);
	if (uap->nss == 0)
		return (0);
	if (error = copyin((caddr_t)uap->nss, (caddr_t)&ss, sizeof (ss)))
		return (error);
	if (ss.ss_flags & SA_DISABLE) {
		if (psp->ps_sigstk.ss_flags & SA_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);
}

struct kill_args {
	int	pid;
	int	signum;
};
/* ARGSUSED */
kill(cp, uap, retval)
	register struct proc *cp;
	register struct kill_args *uap;
	int *retval;
{
	register struct proc *p;
	register struct pcred *pc = cp->p_cred;

	if ((u_int)uap->signum >= NSIG)
		return (EINVAL);
	if (uap->pid > 0) {
		/* kill single process */
		if ((p = pfind(uap->pid)) == NULL)
			return (ESRCH);
		if (!CANSIGNAL(cp, pc, p, uap->signum))
			return (EPERM);
		if (uap->signum)
			psignal(p, uap->signum);
		return (0);
	}
	switch (uap->pid) {
	case -1:		/* broadcast signal */
		return (killpg1(cp, uap->signum, 0, 1));
	case 0:			/* signal own process group */
		return (killpg1(cp, uap->signum, 0, 0));
	default:		/* negative explicit process group */
		return (killpg1(cp, uap->signum, -uap->pid, 0));
	}
	/* NOTREACHED */
}

#if defined(COMPAT_43) || defined(COMPAT_SUNOS)
struct okillpg_args {
	int	pgid;
	int	signum;
};
/* ARGSUSED */
okillpg(p, uap, retval)
	struct proc *p;
	register struct okillpg_args *uap;
	int *retval;
{

	if ((u_int)uap->signum >= NSIG)
		return (EINVAL);
	return (killpg1(p, uap->signum, uap->pgid, 0));
}
#endif /* COMPAT_43 || COMPAT_SUNOS */

/*
 * Common code for kill process group/broadcast kill.
 * cp is calling process.
 */
killpg1(cp, signum, pgid, all)
	register struct proc *cp;
	int signum, pgid, all;
{
	register struct proc *p;
	register struct pcred *pc = cp->p_cred;
	struct pgrp *pgrp;
	int nfound = 0;
	
	if (all)	
		/* 
		 * broadcast 
		 */
		for (p = (struct proc *)allproc; p != NULL; p = p->p_next) {
			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);
		}
		for (p = pgrp->pg_mem; p != NULL; p = p->p_pgrpnxt) {
			if (p->p_pid <= 1 || p->p_flag & P_SYSTEM ||
			    p->p_stat == SZOMB ||
			    !CANSIGNAL(cp, pc, p, signum))
				continue;
			nfound++;
			if (signum)
				psignal(p, signum);
		}
	}
	return (nfound ? 0 : ESRCH);
}

/*
 * Send a signal to a process group.
 */
void
gsignal(pgid, signum)
	int pgid, signum;
{
	struct pgrp *pgrp;

	if (pgid && (pgrp = pgfind(pgid)))
		pgsignal(pgrp, signum, 0);
}

/*