4.2BSD/usr/src/sys/sys/kern_sig.c
/* kern_sig.c 6.2 83/09/08 */
#include "../machine/reg.h"
#include "../machine/pte.h"
#include "../machine/psl.h"
#include "../h/param.h"
#include "../h/systm.h"
#include "../h/dir.h"
#include "../h/user.h"
#include "../h/inode.h"
#include "../h/proc.h"
#include "../h/timeb.h"
#include "../h/times.h"
#include "../h/conf.h"
#include "../h/buf.h"
#include "../h/mount.h"
#include "../h/text.h"
#include "../h/seg.h"
#include "../h/vm.h"
#include "../h/acct.h"
#include "../h/uio.h"
#include "../h/kernel.h"
#include "../h/nami.h"
#define mask(s) (1 << ((s)-1))
#define cantmask (mask(SIGKILL)|mask(SIGCONT)|mask(SIGSTOP))
sigvec()
{
register struct a {
int signo;
struct sigvec *nsv;
struct sigvec *osv;
} *uap = (struct a *)u.u_ap;
struct sigvec vec;
register struct sigvec *sv;
register int sig;
sig = uap->signo;
if (sig <= 0 || sig >= NSIG || sig == SIGKILL || sig == SIGSTOP) {
u.u_error = EINVAL;
return;
}
sv = &vec;
if (uap->osv) {
sv->sv_handler = u.u_signal[sig];
sv->sv_mask = u.u_sigmask[sig];
sv->sv_onstack = (u.u_sigonstack & mask(sig)) != 0;
u.u_error =
copyout((caddr_t)sv, (caddr_t)uap->osv, sizeof (vec));
if (u.u_error)
return;
}
if (uap->nsv) {
u.u_error =
copyin((caddr_t)uap->nsv, (caddr_t)sv, sizeof (vec));
if (u.u_error)
return;
if (sig == SIGCONT && sv->sv_handler == SIG_IGN) {
u.u_error = EINVAL;
return;
}
setsigvec(sig, sv);
}
}
setsigvec(sig, sv)
int sig;
register struct sigvec *sv;
{
register struct proc *p;
register int bit;
bit = mask(sig);
p = u.u_procp;
/*
* Change setting atomically.
*/
(void) spl6();
u.u_signal[sig] = sv->sv_handler;
u.u_sigmask[sig] = sv->sv_mask &~ cantmask;
if (sv->sv_onstack)
u.u_sigonstack |= bit;
else
u.u_sigonstack &= ~bit;
if (sv->sv_handler == SIG_IGN) {
p->p_sig &= ~bit; /* never to be seen again */
p->p_sigignore |= bit;
p->p_sigcatch &= ~bit;
} else {
p->p_sigignore &= ~bit;
if (sv->sv_handler == SIG_DFL)
p->p_sigcatch &= ~bit;
else
p->p_sigcatch |= bit;
}
(void) spl0();
}
sigblock()
{
struct a {
int sigmask;
} *uap = (struct a *)u.u_ap;
register struct proc *p = u.u_procp;
(void) spl6();
u.u_r.r_val1 = p->p_sigmask;
p->p_sigmask |= uap->sigmask &~ cantmask;
(void) spl0();
}
sigsetmask()
{
struct a {
int sigmask;
} *uap = (struct a *)u.u_ap;
register struct proc *p = u.u_procp;
(void) spl6();
u.u_r.r_val1 = p->p_sigmask;
p->p_sigmask = uap->sigmask &~ cantmask;
(void) spl0();
}
sigpause()
{
struct a {
int sigmask;
} *uap = (struct a *)u.u_ap;
register struct proc *p = u.u_procp;
/*
* 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 proc structure
* to indicate this (should be in u.).
*/
u.u_oldmask = p->p_sigmask;
p->p_flag |= SOMASK;
p->p_sigmask = uap->sigmask &~ cantmask;
for (;;)
sleep((caddr_t)&u, PSLEP);
/*NOTREACHED*/
}
#undef cantmask
#undef mask
sigstack()
{
register struct a {
struct sigstack *nss;
struct sigstack *oss;
} *uap = (struct a *)u.u_ap;
struct sigstack ss;
if (uap->oss) {
u.u_error = copyout((caddr_t)&u.u_sigstack, (caddr_t)uap->oss,
sizeof (struct sigstack));
if (u.u_error)
return;
}
if (uap->nss) {
u.u_error =
copyin((caddr_t)uap->nss, (caddr_t)&ss, sizeof (ss));
if (u.u_error == 0)
u.u_sigstack = ss;
}
}
/* KILL SHOULD BE UPDATED */
kill()
{
register struct a {
int pid;
int signo;
} *uap = (struct a *)u.u_ap;
u.u_error = kill1(uap->signo < 0,
uap->signo < 0 ? -uap->signo : uap->signo, uap->pid);
}
killpg()
{
register struct a {
int pgrp;
int signo;
} *uap = (struct a *)u.u_ap;
u.u_error = kill1(1, uap->signo, uap->pgrp);
}
/* KILL CODE SHOULDNT KNOW ABOUT PROCESS INTERNALS !?! */
kill1(ispgrp, signo, who)
int ispgrp, signo, who;
{
register struct proc *p;
int f, priv = 0;
if (signo < 0 || signo > NSIG)
return (EINVAL);
if (who > 0 && !ispgrp) {
p = pfind(who);
if (p == 0)
return (ESRCH);
if (u.u_uid && u.u_uid != p->p_uid)
return (EPERM);
if (signo)
psignal(p, signo);
return (0);
}
if (who == -1 && u.u_uid == 0)
priv++, who = 0, ispgrp = 1; /* like sending to pgrp */
else if (who == 0) {
/*
* Zero process id means send to my process group.
*/
ispgrp = 1;
who = u.u_procp->p_pgrp;
if (who == 0)
return (EINVAL);
}
for (f = 0, p = proc; p < procNPROC; p++) {
if (p->p_stat == NULL)
continue;
if (!ispgrp) {
if (p->p_pid != who)
continue;
} else if (p->p_pgrp != who && priv == 0 || p->p_ppid == 0 ||
(p->p_flag&SSYS) || (priv && p == u.u_procp))
continue;
if (u.u_uid != 0 && u.u_uid != p->p_uid &&
(signo != SIGCONT || !inferior(p)))
continue;
f++;
if (signo)
psignal(p, signo);
}
return (f == 0 ? ESRCH : 0);
}
/*
* Send the specified signal to
* all processes with 'pgrp' as
* process group.
*/
gsignal(pgrp, sig)
register int pgrp;
{
register struct proc *p;
if (pgrp == 0)
return;
for(p = proc; p < procNPROC; p++)
if (p->p_pgrp == pgrp)
psignal(p, sig);
}
/*
* Send the specified signal to
* the specified process.
*/
psignal(p, sig)
register struct proc *p;
register int sig;
{
register int s;
register int (*action)();
int sigmask;
if ((unsigned)sig >= NSIG)
return;
sigmask = 1 << (sig-1);
/*
* If proc is traced, always give parent a chance.
*/
if (p->p_flag & STRC)
action = SIG_DFL;
else {
/*
* If the signal is being ignored,
* then we forget about it immediately.
*/
if (p->p_sigignore & sigmask)
return;
if (p->p_sigmask & sigmask)
action = SIG_HOLD;
else if (p->p_sigcatch & sigmask)
action = SIG_CATCH;
else
action = SIG_DFL;
}
#define mask(sig) (1<<(sig-1))
#define stops (mask(SIGSTOP)|mask(SIGTSTP)|mask(SIGTTIN)|mask(SIGTTOU))
if (sig) {
p->p_sig |= sigmask;
switch (sig) {
case SIGTERM:
if ((p->p_flag&STRC) || action != SIG_DFL)
break;
/* fall into ... */
case SIGKILL:
if (p->p_nice > NZERO)
p->p_nice = NZERO;
break;
case SIGCONT:
p->p_sig &= ~stops;
break;
case SIGSTOP:
case SIGTSTP:
case SIGTTIN:
case SIGTTOU:
p->p_sig &= ~mask(SIGCONT);
break;
}
}
#undef mask
#undef stops
/*
* Defer further processing for signals which are held.
*/
if (action == SIG_HOLD)
return;
s = spl6();
switch (p->p_stat) {
case SSLEEP:
/*
* If process is sleeping at negative priority
* we can't interrupt the sleep... the signal will
* be noticed when the process returns through
* trap() or syscall().
*/
if (p->p_pri <= PZERO)
goto out;
/*
* Process is sleeping and traced... make it runnable
* so it can discover the signal in issig() and stop
* for the parent.
*/
if (p->p_flag&STRC)
goto run;
switch (sig) {
case SIGSTOP:
case SIGTSTP:
case SIGTTIN:
case SIGTTOU:
/*
* These are the signals which by default
* stop a process.
*/
if (action != SIG_DFL)
goto run;
/*
* Don't clog system with children of init
* stopped from the keyboard.
*/
if (sig != SIGSTOP && p->p_pptr == &proc[1]) {
psignal(p, SIGKILL);
p->p_sig &= ~sigmask;
splx(s);
return;
}
/*
* If a child in vfork(), stopping could
* cause deadlock.
*/
if (p->p_flag&SVFORK)
goto out;
p->p_sig &= ~sigmask;
p->p_cursig = sig;
stop(p);
goto out;
case SIGIO:
case SIGURG:
case SIGCHLD:
/*
* These signals are special in that they
* don't get propogated... if the process
* isn't interested, forget it.
*/
if (action != SIG_DFL)
goto run;
p->p_sig &= ~sigmask; /* take it away */
goto out;
default:
/*
* All other signals cause the process to run
*/
goto run;
}
/*NOTREACHED*/
case SSTOP:
/*
* If traced process is already stopped,
* then no further action is necessary.
*/
if (p->p_flag&STRC)
goto out;
switch (sig) {
case SIGKILL:
/*
* Kill signal always sets processes running.
*/
goto run;
case SIGCONT:
/*
* 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 || p->p_wchan == 0)
goto run;
p->p_stat = SSLEEP;
goto out;
case SIGSTOP:
case SIGTSTP:
case SIGTTIN:
case SIGTTOU:
/*
* Already stopped, don't need to stop again.
* (If we did the shell could get confused.)
*/
p->p_sig &= ~sigmask; /* take it away */
goto out;
default:
/*
* If process is sleeping interruptibly, then
* unstick it so that when it is continued
* it can look at the signal.
* But don't setrun the process as its not to
* be unstopped by the signal alone.
*/
if (p->p_wchan && p->p_pri > PZERO)
unsleep(p);
goto out;
}
/*NOTREACHED*/
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.
*/
if (p == u.u_procp && !noproc)
#include "../vax/mtpr.h"
aston();
goto out;
}
/*NOTREACHED*/
run:
/*
* Raise priority to at least PUSER.
*/
if (p->p_pri > PUSER)
if ((p != u.u_procp || noproc) && p->p_stat == SRUN &&
(p->p_flag & SLOAD)) {
remrq(p);
p->p_pri = PUSER;
setrq(p);
} else
p->p_pri = PUSER;
setrun(p);
out:
splx(s);
}
/*
* Returns true if the current
* process has a signal to process.
* The signal to process is put in p_cursig.
* This is asked at least once each time a process enters the
* system (though this can usually be done without actually
* calling issig by checking the pending signal masks.)
* A signal does not do anything
* directly to a process; it sets
* a flag that asks the process to
* do something to itself.
*/
issig()
{
register struct proc *p;
register int sig;
int sigbits, sigmask;
p = u.u_procp;
for (;;) {
sigbits = p->p_sig &~ p->p_sigmask;
if ((p->p_flag&STRC) == 0)
sigbits &= ~p->p_sigignore;
if (p->p_flag&SVFORK)
#define bit(a) (1<<(a-1))
sigbits &= ~(bit(SIGSTOP)|bit(SIGTSTP)|bit(SIGTTIN)|bit(SIGTTOU));
if (sigbits == 0)
break;
sig = ffs(sigbits);
sigmask = 1 << (sig-1);
p->p_sig &= ~sigmask; /* take the signal! */
p->p_cursig = sig;
if (p->p_flag&STRC && (p->p_flag&SVFORK) == 0) {
/*
* If traced, always stop, and stay
* stopped until released by the parent.
*/
do {
stop(p);
swtch();
} while (!procxmt() && p->p_flag&STRC);
/*
* If the traced bit got turned off,
* then put the signal taken above back into p_sig
* and go back up to the top to rescan signals.
* This ensures that p_sig* and u_signal are consistent.
*/
if ((p->p_flag&STRC) == 0) {
p->p_sig |= sigmask;
continue;
}
/*
* If parent wants us to take the signal,
* then it will leave it in p->p_cursig;
* otherwise we just look for signals again.
*/
sig = p->p_cursig;
if (sig == 0)
continue;
/*
* If signal is being masked put it back
* into p_sig and look for other signals.
*/
sigmask = 1 << (sig-1);
if (p->p_sigmask & sigmask) {
p->p_sig |= sigmask;
continue;
}
}
switch (u.u_signal[sig]) {
case SIG_DFL:
/*
* Don't take default actions on system processes.
*/
if (p->p_ppid == 0)
break;
switch (sig) {
case SIGTSTP:
case SIGTTIN:
case SIGTTOU:
/*
* Children of init aren't allowed to stop
* on signals from the keyboard.
*/
if (p->p_pptr == &proc[1]) {
psignal(p, SIGKILL);
continue;
}
/* fall into ... */
case SIGSTOP:
if (p->p_flag&STRC)
continue;
stop(p);
swtch();
continue;
case SIGCONT:
case SIGCHLD:
case SIGURG:
case SIGIO:
/*
* These signals are normally not
* sent if the action is the default.
*/
continue; /* == ignore */
default:
goto send;
}
/*NOTREACHED*/
case SIG_HOLD:
case SIG_IGN:
/*
* Masking above should prevent us
* ever trying to take action on a held
* or ignored signal, unless process is traced.
*/
if ((p->p_flag&STRC) == 0)
printf("issig\n");
continue;
default:
/*
* This signal has an action, let
* psig process it.
*/
goto send;
}
/*NOTREACHED*/
}
/*
* Didn't find a signal to send.
*/
p->p_cursig = 0;
return (0);
send:
/*
* Let psig process the signal.
*/
return (sig);
}
/*
* Put the argument process into the stopped
* state and notify the parent via wakeup and/or signal.
*/
stop(p)
register struct proc *p;
{
p->p_stat = SSTOP;
p->p_flag &= ~SWTED;
wakeup((caddr_t)p->p_pptr);
/*
* Avoid sending signal to parent if process is traced
*/
if (p->p_flag&STRC)
return;
psignal(p->p_pptr, SIGCHLD);
}
/*
* Perform the action specified by
* the current signal.
* The usual sequence is:
* if (issig())
* psig();
* The signal bit has already been cleared by issig,
* and the current signal number stored in p->p_cursig.
*/
psig()
{
register struct proc *p = u.u_procp;
register int sig = p->p_cursig;
int sigmask = 1 << (sig - 1), returnmask;
register int (*action)();
if (sig == 0)
panic("psig");
action = u.u_signal[sig];
if (action != SIG_DFL) {
if (action == SIG_IGN || (p->p_sigmask & sigmask))
panic("psig action");
u.u_error = 0;
/*
* Set the new mask value and also defer further
* occurences of this signal (unless we're simulating
* the old signal facilities).
*
* 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.
*/
(void) spl6();
if (p->p_flag & SOUSIG) {
if (sig != SIGILL && sig != SIGTRAP) {
u.u_signal[sig] = SIG_DFL;
p->p_sigcatch &= ~sigmask;
}
sigmask = 0;
}
if (p->p_flag & SOMASK) {
returnmask = u.u_oldmask;
p->p_flag &= ~SOMASK;
} else
returnmask = p->p_sigmask;
p->p_sigmask |= u.u_sigmask[sig] | sigmask;
(void) spl0();
u.u_ru.ru_nsignals++;
sendsig(action, sig, returnmask);
p->p_cursig = 0;
return;
}
u.u_acflag |= AXSIG;
switch (sig) {
case SIGILL:
case SIGIOT:
case SIGBUS:
case SIGQUIT:
case SIGTRAP:
case SIGEMT:
case SIGFPE:
case SIGSEGV:
case SIGSYS:
u.u_arg[0] = sig;
if (core())
sig += 0200;
}
exit(sig);
}
/*
* Create a core image on the file "core"
* If you are looking for protection glitches,
* there are probably a wealth of them here
* when this occurs to a suid command.
*
* It writes UPAGES block of the
* user.h area followed by the entire
* data+stack segments.
*/
core()
{
register struct inode *ip;
extern schar();
if (u.u_uid != u.u_ruid || u.u_gid != u.u_rgid)
return (0);
if (ctob(UPAGES+u.u_dsize+u.u_ssize) >=
u.u_rlimit[RLIMIT_CORE].rlim_cur)
return (0);
u.u_error = 0;
u.u_dirp = "core";
ip = namei(schar, CREATE, 1);
if (ip == NULL) {
if (u.u_error)
return (0);
ip = maknode(0644);
if (ip==NULL)
return (0);
}
if (access(ip, IWRITE) ||
(ip->i_mode&IFMT) != IFREG ||
ip->i_nlink != 1) {
u.u_error = EFAULT;
goto out;
}
itrunc(ip, (u_long)0);
u.u_acflag |= ACORE;
u.u_error = rdwri(UIO_WRITE, ip,
(caddr_t)&u,
ctob(UPAGES),
0, 1, (int *)0);
if (u.u_error == 0)
u.u_error = rdwri(UIO_WRITE, ip,
(caddr_t)ctob(dptov(u.u_procp, 0)),
ctob(u.u_dsize),
ctob(UPAGES), 0, (int *)0);
if (u.u_error == 0)
u.u_error = rdwri(UIO_WRITE, ip,
(caddr_t)ctob(sptov(u.u_procp, u.u_ssize - 1)),
ctob(u.u_ssize),
ctob(UPAGES)+ctob(u.u_dsize), 0, (int *)0);
out:
iput(ip);
return (u.u_error == 0);
}