/*-
* Copyright (c) 2006, 2007, 2008, 2019, 2023 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
* by Andrew Doran.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
/*
* Copyright (c) 1982, 1986, 1989, 1991, 1993
* The Regents of the University of California. All rights reserved.
* (c) UNIX System Laboratories, Inc.
* All or some portions of this file are derived from material licensed
* to the University of California by American Telephone and Telegraph
* Co. or Unix System Laboratories, Inc. and are reproduced herein with
* the permission of UNIX System Laboratories, Inc.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* @(#)kern_sig.c 8.14 (Berkeley) 5/14/95
*/
/*
* sigactsinit:
*
* Create an initial sigacts structure, using the same signal state
* as of specified process. If 'share' is set, share the sigacts by
* holding a reference, otherwise just copy it from parent.
*/
struct sigacts *
sigactsinit(struct proc *pp, int share)
{
struct sigacts *ps = pp->p_sigacts, *ps2;
/*
* sigactsunshare:
*
* Make this process not share its sigacts, maintaining all signal state.
*/
void
sigactsunshare(struct proc *p)
{
struct sigacts *ps, *oldps = p->p_sigacts;
if (__predict_true(oldps->sa_refcnt == 1))
return;
/*
* siginit:
*
* Initialize signal state for process 0; set to ignore signals that
* are ignored by default and disable the signal stack. Locking not
* required as the system is still cold.
*/
void
siginit(struct proc *p)
{
struct lwp *l;
struct sigacts *ps;
int signo, prop;
/*
* Reset per LWP state.
*/
l = LIST_FIRST(&p->p_lwps);
l->l_sigwaited = NULL;
l->l_sigstk = SS_INIT;
ksiginfo_queue_init(&l->l_sigpend.sp_info);
sigemptyset(&l->l_sigpend.sp_set);
/* One reference. */
ps->sa_refcnt = 1;
}
/*
* execsigs:
*
* Reset signals for an exec of the specified process.
*/
void
execsigs(struct proc *p)
{
struct sigacts *ps;
struct lwp *l;
int signo, prop;
sigset_t tset;
ksiginfoq_t kq;
KASSERT(p->p_nlwps == 1);
sigactsunshare(p);
ps = p->p_sigacts;
/*
* Reset caught signals. Held signals remain held through
* l->l_sigmask (unless they were caught, and are now ignored
* by default).
*
* No need to lock yet, the process has only one LWP and
* at this point the sigacts are private to the process.
*/
sigemptyset(&tset);
for (signo = 1; signo < NSIG; signo++) {
if (sigismember(&p->p_sigctx.ps_sigcatch, signo)) {
prop = sigprop[signo];
if (prop & SA_IGNORE) {
if ((prop & SA_CONT) == 0)
sigaddset(&p->p_sigctx.ps_sigignore,
signo);
sigaddset(&tset, signo);
}
SIGACTION_PS(ps, signo).sa_handler = SIG_DFL;
}
sigemptyset(&SIGACTION_PS(ps, signo).sa_mask);
SIGACTION_PS(ps, signo).sa_flags = SA_RESTART;
}
ksiginfo_queue_init(&kq);
/*
* Reset no zombies if child dies flag as Solaris does.
*/
p->p_flag &= ~(PK_NOCLDWAIT | PK_CLDSIGIGN);
if (SIGACTION_PS(ps, SIGCHLD).sa_handler == SIG_IGN)
SIGACTION_PS(ps, SIGCHLD).sa_handler = SIG_DFL;
/*
* ksiginfo_alloc:
*
* Allocate a new ksiginfo structure from the pool, and optionally copy
* an existing one. If the existing ksiginfo_t is from the pool, and
* has not been queued somewhere, then just return it. Additionally,
* if the existing ksiginfo_t does not contain any information beyond
* the signal number, then just return it.
*/
ksiginfo_t *
ksiginfo_alloc(struct proc *p, ksiginfo_t *ok, int flags)
{
ksiginfo_t *kp;
if (ok != NULL) {
if ((ok->ksi_flags & (KSI_QUEUED | KSI_FROMPOOL)) ==
KSI_FROMPOOL)
return ok;
if (KSI_EMPTY_P(ok))
return ok;
}
kp = pool_cache_get(ksiginfo_cache, flags);
if (kp == NULL) {
#ifdef DIAGNOSTIC
printf("Out of memory allocating ksiginfo for pid %d\n",
p->p_pid);
#endif
return NULL;
}
static int
siggetinfo(sigpend_t *sp, ksiginfo_t *out, int signo)
{
ksiginfo_t *ksi, *nksi;
if (sp == NULL)
goto out;
/* Find siginfo and copy it out. */
int count = 0;
TAILQ_FOREACH_SAFE(ksi, &sp->sp_info, ksi_list, nksi) {
if (ksi->ksi_signo != signo)
continue;
if (count++ > 0) /* Only remove the first, count all of them */
continue;
TAILQ_REMOVE(&sp->sp_info, ksi, ksi_list);
KASSERT((ksi->ksi_flags & KSI_FROMPOOL) != 0);
KASSERT((ksi->ksi_flags & KSI_QUEUED) != 0);
ksi->ksi_flags &= ~KSI_QUEUED;
if (out != NULL) {
memcpy(out, ksi, sizeof(*out));
out->ksi_flags &= ~(KSI_FROMPOOL | KSI_QUEUED);
}
ksiginfo_free(ksi);
}
if (count)
return count;
out:
/* If there is no siginfo, then manufacture it. */
if (out != NULL) {
KSI_INIT(out);
out->ksi_info._signo = signo;
out->ksi_info._code = SI_NOINFO;
}
return 0;
}
/*
* sigget:
*
* Fetch the first pending signal from a set. Optionally, also fetch
* or manufacture a ksiginfo element. Returns the number of the first
* pending signal, or zero.
*/
int
sigget(sigpend_t *sp, ksiginfo_t *out, int signo, const sigset_t *mask)
{
sigset_t tset;
int count;
/* If there's no pending set, the signal is from the debugger. */
if (sp == NULL)
goto out;
/* Construct mask from signo, and 'mask'. */
if (signo == 0) {
if (mask != NULL) {
tset = *mask;
__sigandset(&sp->sp_set, &tset);
} else
tset = sp->sp_set;
/* If there are no signals pending - return. */
if ((signo = firstsig(&tset)) == 0)
goto out;
} else {
KASSERT(sigismember(&sp->sp_set, signo));
}
/*
* sigput:
*
* Append a new ksiginfo element to the list of pending ksiginfo's.
*/
static int
sigput(sigpend_t *sp, struct proc *p, ksiginfo_t *ksi)
{
ksiginfo_t *kp;
/*
* sigclearall:
*
* Clear all pending signals in the specified set from a process and
* its LWPs.
*/
void
sigclearall(struct proc *p, const sigset_t *mask, ksiginfoq_t *kq)
{
struct lwp *l;
/*
* sigispending:
*
* Return the first signal number if there are pending signals for the
* current LWP. May be called unlocked provided that LW_PENDSIG is set,
* and that the signal has been posted to the appopriate queue before
* LW_PENDSIG is set.
*
* This should only ever be called with (l == curlwp), unless the
* result does not matter (procfs, sysctl).
*/
int
sigispending(struct lwp *l, int signo)
{
struct proc *p = l->l_proc;
sigset_t tset;
/*
* If there was stack information, update whether or not we are
* still running on an alternate signal stack.
*/
if ((ucp->uc_flags & _UC_STACK) != 0) {
if (ucp->uc_stack.ss_flags & SS_ONSTACK)
l->l_sigstk.ss_flags |= SS_ONSTACK;
else
l->l_sigstk.ss_flags &= ~SS_ONSTACK;
}
return 0;
}
/*
* killpg1: common code for kill process group/broadcast kill.
*/
int
killpg1(struct lwp *l, ksiginfo_t *ksi, int pgid, int all)
{
struct proc *p, *cp;
kauth_cred_t pc;
struct pgrp *pgrp;
int nfound;
int signo = ksi->ksi_signo;
cp = l->l_proc;
pc = l->l_cred;
nfound = 0;
mutex_enter(&proc_lock);
if (all) {
/*
* Broadcast.
*/
PROCLIST_FOREACH(p, &allproc) {
if (p->p_pid <= 1 || p == cp ||
(p->p_flag & PK_SYSTEM) != 0)
continue;
mutex_enter(p->p_lock);
if (kauth_authorize_process(pc,
KAUTH_PROCESS_SIGNAL, p, KAUTH_ARG(signo), NULL,
NULL) == 0) {
nfound++;
if (signo)
kpsignal2(p, ksi);
}
mutex_exit(p->p_lock);
}
} else {
if (pgid == 0)
/* Zero pgid means send to my process group. */
pgrp = cp->p_pgrp;
else {
pgrp = pgrp_find(pgid);
if (pgrp == NULL)
goto out;
}
LIST_FOREACH(p, &pgrp->pg_members, p_pglist) {
if (p->p_pid <= 1 || p->p_flag & PK_SYSTEM)
continue;
mutex_enter(p->p_lock);
if (kauth_authorize_process(pc, KAUTH_PROCESS_SIGNAL,
p, KAUTH_ARG(signo), NULL, NULL) == 0) {
nfound++;
if (signo && P_ZOMBIE(p) == 0)
kpsignal2(p, ksi);
}
mutex_exit(p->p_lock);
}
}
out:
mutex_exit(&proc_lock);
return nfound ? 0 : ESRCH;
}
/*
* Send a signal to a process group. If checktty is set, limit to members
* which have a controlling terminal.
*/
void
pgsignal(struct pgrp *pgrp, int sig, int checkctty)
{
ksiginfo_t ksi;
/*
* Send a signal caused by a trap to the current LWP. If it will be caught
* immediately, deliver it with correct code. Otherwise, post it normally.
*/
void
trapsignal(struct lwp *l, ksiginfo_t *ksi)
{
struct proc *p;
struct sigacts *ps;
int signo = ksi->ksi_signo;
sigset_t *mask;
sig_t action;
repeat:
/*
* If we are exiting, demise now.
*
* This avoids notifying tracer and deadlocking.
*/
if (__predict_false(ISSET(p->p_sflag, PS_WEXIT))) {
mutex_exit(p->p_lock);
mutex_exit(&proc_lock);
lwp_exit(l);
panic("trapsignal");
/* NOTREACHED */
}
/*
* The process is already stopping.
*/
if ((p->p_sflag & PS_STOPPING) != 0) {
mutex_exit(&proc_lock);
sigswitch_unlock_and_switch_away(l);
mutex_enter(&proc_lock);
mutex_enter(p->p_lock);
goto repeat;
}
if (ktrpoint(KTR_PSIG)) {
if (p->p_emul->e_ktrpsig)
p->p_emul->e_ktrpsig(signo, action, mask, ksi);
else
ktrpsig(signo, action, mask, ksi);
}
return;
}
/*
* If the signal is masked or ignored, then unmask it and
* reset it to the default action so that the process or
* its tracer will be notified.
*/
const bool ignored = action == SIG_IGN;
if (masked || ignored) {
mutex_enter(&ps->sa_mutex);
sigdelset(mask, signo);
sigdelset(&p->p_sigctx.ps_sigcatch, signo);
sigdelset(&p->p_sigctx.ps_sigignore, signo);
sigdelset(&SIGACTION_PS(ps, signo).sa_mask, signo);
SIGACTION_PS(ps, signo).sa_handler = SIG_DFL;
mutex_exit(&ps->sa_mutex);
}
/*
* Fill in signal information and signal the parent for a child status change.
*/
void
child_psignal(struct proc *p, int mask)
{
ksiginfo_t ksi;
struct proc *q;
int xsig;
/*
* sigismasked:
*
* Returns true if signal is ignored or masked for the specified LWP.
*/
int
sigismasked(struct lwp *l, int sig)
{
struct proc *p = l->l_proc;
/*
* sigpost:
*
* Post a pending signal to an LWP. Returns non-zero if the LWP may
* be able to take the signal.
*/
static int
sigpost(struct lwp *l, sig_t action, int prop, int sig)
{
int rv, masked;
struct proc *p = l->l_proc;
KASSERT(mutex_owned(p->p_lock));
/*
* If the LWP is on the way out, sigclear() will be busy draining all
* pending signals. Don't give it more.
*/
if (l->l_stat == LSZOMB)
return 0;
/*
* Have the LWP check for signals. This ensures that even if no LWP
* is found to take the signal immediately, it should be taken soon.
*/
signotify(l);
/*
* SIGCONT can be masked, but if LWP is stopped, it needs restart.
* Note: SIGKILL and SIGSTOP cannot be masked.
*/
masked = sigismember(&l->l_sigmask, sig);
if (masked && ((prop & SA_CONT) == 0 || l->l_stat != LSSTOP)) {
lwp_unlock(l);
return 0;
}
/*
* If killing the process, make it run fast.
*/
if (__predict_false((prop & SA_KILL) != 0) &&
action == SIG_DFL && l->l_priority < MAXPRI_USER) {
KASSERT(l->l_class == SCHED_OTHER);
lwp_changepri(l, MAXPRI_USER);
}
/*
* If the LWP is running or on a run queue, then we win. If it's
* sleeping interruptably, wake it and make it take the signal. If
* the sleep isn't interruptable, then the chances are it will get
* to see the signal soon anyhow. If suspended, it can't take the
* signal right now. If it's LWP private or for all LWPs, save it
* for later; otherwise punt.
*/
rv = 0;
switch (l->l_stat) {
case LSRUN:
case LSONPROC:
rv = 1;
break;
case LSSLEEP:
if ((l->l_flag & LW_SINTR) != 0) {
/* setrunnable() will release the lock. */
setrunnable(l);
return 1;
}
break;
case LSSUSPENDED:
if ((prop & SA_KILL) != 0 && (l->l_flag & LW_WCORE) != 0) {
/* lwp_continue() will release the lock. */
lwp_continue(l);
return 1;
}
break;
case LSSTOP:
if ((prop & SA_STOP) != 0)
break;
/*
* If the LWP is stopped and we are sending a continue
* signal, then start it again.
*/
if ((prop & SA_CONT) != 0) {
if (l->l_wchan != NULL) {
l->l_stat = LSSLEEP;
p->p_nrlwps++;
rv = 1;
break;
}
/* setrunnable() will release the lock. */
setrunnable(l);
return 1;
} else if (l->l_wchan == NULL || (l->l_flag & LW_SINTR) != 0) {
/* setrunnable() will release the lock. */
setrunnable(l);
return 1;
}
break;
default:
break;
}
lwp_unlock(l);
return rv;
}
/*
* Notify an LWP that it has a pending signal.
*/
void
signotify(struct lwp *l)
{
KASSERT(lwp_locked(l, NULL));
l->l_flag |= LW_PENDSIG;
lwp_need_userret(l);
}
/*
* Find an LWP within process p that is waiting on signal ksi, and hand
* it on.
*/
static int
sigunwait(struct proc *p, const ksiginfo_t *ksi)
{
struct lwp *l;
int signo;
KASSERT(mutex_owned(p->p_lock));
signo = ksi->ksi_signo;
if (ksi->ksi_lid != 0) {
/*
* Signal came via _lwp_kill(). Find the LWP and see if
* it's interested.
*/
if ((l = lwp_find(p, ksi->ksi_lid)) == NULL)
return 0;
if (l->l_sigwaited == NULL ||
!sigismember(&l->l_sigwaitset, signo))
return 0;
} else {
/*
* Look for any LWP that may be interested.
*/
LIST_FOREACH(l, &p->p_sigwaiters, l_sigwaiter) {
KASSERT(l->l_sigwaited != NULL);
if (sigismember(&l->l_sigwaitset, signo))
break;
}
}
/*
* 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.
*/
int
kpsignal2(struct proc *p, ksiginfo_t *ksi)
{
int prop, signo = ksi->ksi_signo;
struct lwp *l = NULL;
ksiginfo_t *kp;
lwpid_t lid;
sig_t action;
bool toall;
bool traced;
int error = 0;
/*
* If the process is being created by fork, is a zombie or is
* exiting, then just drop the signal here and bail out.
*/
if (p->p_stat != SACTIVE && p->p_stat != SSTOP)
return 0;
/*
* Notify any interested parties of the signal.
*/
KNOTE(&p->p_klist, NOTE_SIGNAL | signo);
/*
* Some signals including SIGKILL must act on the entire process.
*/
kp = NULL;
prop = sigprop[signo];
toall = ((prop & SA_TOALL) != 0);
lid = toall ? 0 : ksi->ksi_lid;
traced = ISSET(p->p_slflag, PSL_TRACED) &&
!sigismember(&p->p_sigctx.ps_sigpass, signo);
/*
* If proc is traced, always give parent a chance.
*/
if (traced) {
action = SIG_DFL;
if (lid == 0) {
/*
* If the process is being traced and the signal
* is being caught, make sure to save any ksiginfo.
*/
if ((kp = ksiginfo_alloc(p, ksi, PR_NOWAIT)) == NULL)
goto discard;
if ((error = sigput(&p->p_sigpend, p, kp)) != 0)
goto out;
}
} else {
/*
* If the signal is being ignored, then drop it. Note: we
* don't set SIGCONT in ps_sigignore, and if it is set to
* SIG_IGN, action will be SIG_DFL here.
*/
if (sigismember(&p->p_sigctx.ps_sigignore, signo))
goto discard;
/*
* 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)
goto discard;
/*
* If stopping or continuing a process, discard any pending
* signals that would do the inverse.
*/
if ((prop & (SA_CONT | SA_STOP)) != 0) {
ksiginfoq_t kq;
/*
* If the signal doesn't have SA_CANTMASK (no override for SIGKILL,
* please!), check if any LWPs are waiting on it. If yes, pass on
* the signal info. The signal won't be processed further here.
*/
if ((prop & SA_CANTMASK) == 0 && !LIST_EMPTY(&p->p_sigwaiters) &&
p->p_stat == SACTIVE && (p->p_sflag & PS_STOPPING) == 0 &&
sigunwait(p, ksi))
goto discard;
/*
* XXXSMP Should be allocated by the caller, we're holding locks
* here.
*/
if (kp == NULL && (kp = ksiginfo_alloc(p, ksi, PR_NOWAIT)) == NULL)
goto discard;
/*
* LWP private signals are easy - just find the LWP and post
* the signal to it.
*/
if (lid != 0) {
l = lwp_find(p, lid);
if (l != NULL) {
if ((error = sigput(&l->l_sigpend, p, kp)) != 0)
goto out;
membar_producer();
if (sigpost(l, action, prop, kp->ksi_signo) != 0)
signo = -1;
}
goto out;
}
/*
* Some signals go to all LWPs, even if posted with _lwp_kill()
* or for an SA process.
*/
if (p->p_stat == SACTIVE && (p->p_sflag & PS_STOPPING) == 0) {
if (traced)
goto deliver;
/*
* If SIGCONT is default (or ignored) and process is
* asleep, we are finished; the process should not
* be awakened.
*/
if ((prop & SA_CONT) != 0 && action == SIG_DFL)
goto out;
} else {
/*
* Process is stopped or stopping.
* - If traced, then no action is needed, unless killing.
* - Run the process only if sending SIGCONT or SIGKILL.
*/
if (traced && signo != SIGKILL) {
goto out;
}
if ((prop & SA_CONT) != 0 || signo == SIGKILL) {
/*
* Re-adjust p_nstopchild if the process was
* stopped but not yet collected by its parent.
*/
if (p->p_stat == SSTOP && !p->p_waited)
p->p_pptr->p_nstopchild--;
p->p_stat = SACTIVE;
p->p_sflag &= ~PS_STOPPING;
if (traced) {
KASSERT(signo == SIGKILL);
goto deliver;
}
/*
* Do not make signal pending if SIGCONT is default.
*
* If the process catches SIGCONT, let it handle the
* signal itself (if waiting on event - process runs,
* otherwise continues sleeping).
*/
if ((prop & SA_CONT) != 0) {
p->p_xsig = SIGCONT;
p->p_sflag |= PS_CONTINUED;
child_psignal(p, 0);
if (action == SIG_DFL) {
KASSERT(signo != SIGKILL);
goto deliver;
}
}
} else if ((prop & SA_STOP) != 0) {
/*
* Already stopped, don't need to stop again.
* (If we did the shell could get confused.)
*/
goto out;
}
}
/*
* Make signal pending.
*/
KASSERT(!traced);
if ((error = sigput(&p->p_sigpend, p, kp)) != 0)
goto out;
deliver:
/*
* Before we set LW_PENDSIG on any LWP, ensure that the signal is
* visible on the per process list (for sigispending()). This
* is unlikely to be needed in practice, but...
*/
membar_producer();
/*
* Try to find an LWP that can take the signal.
*/
LIST_FOREACH(l, &p->p_lwps, l_sibling) {
if (sigpost(l, action, prop, kp->ksi_signo) && !toall)
break;
}
signo = -1;
out:
/*
* If the ksiginfo wasn't used, then bin it. XXXSMP freeing memory
* with locks held. The caller should take care of this.
*/
ksiginfo_free(kp);
if (signo == -1)
return error;
discard:
SDT_PROBE(proc, kernel, , signal__discard, l, p, signo, 0, 0);
return error;
}
/*
* Finish stopping of a process. Mark it stopped and notify the parent.
*
* Drop p_lock briefly if ppsig is true.
*/
static void
proc_stop_done(struct proc *p, int ppmask)
{
/*
* Stop the current process and switch away to the debugger notifying
* an event specific to a traced process only.
*/
void
eventswitch(int code, int pe_report_event, int entity)
{
struct lwp *l = curlwp;
struct proc *p = l->l_proc;
struct sigacts *ps;
sigset_t *mask;
sig_t action;
ksiginfo_t ksi;
const int signo = SIGTRAP;
repeat:
/*
* If we are exiting, demise now.
*
* This avoids notifying tracer and deadlocking.
*/
if (__predict_false(ISSET(p->p_sflag, PS_WEXIT))) {
mutex_exit(p->p_lock);
mutex_exit(&proc_lock);
if (pe_report_event == PTRACE_LWP_EXIT) {
/* Avoid double lwp_exit() and panic. */
return;
}
/*
* If we are no longer traced, abandon this event signal.
*
* This avoids killing a process after detaching the debugger.
*/
if (__predict_false(!ISSET(p->p_slflag, PSL_TRACED))) {
mutex_exit(p->p_lock);
mutex_exit(&proc_lock);
return;
}
/*
* If there's a pending SIGKILL process it immediately.
*/
if (p->p_xsig == SIGKILL ||
sigismember(&p->p_sigpend.sp_set, SIGKILL)) {
mutex_exit(p->p_lock);
mutex_exit(&proc_lock);
return;
}
/*
* The process is already stopping.
*/
if ((p->p_sflag & PS_STOPPING) != 0) {
mutex_exit(&proc_lock);
sigswitch_unlock_and_switch_away(l);
mutex_enter(&proc_lock);
mutex_enter(p->p_lock);
goto repeat;
}
if (code == TRAP_CHLD) {
mutex_enter(&proc_lock);
while (l->l_vforkwaiting)
cv_wait(&l->l_waitcv, &proc_lock);
mutex_exit(&proc_lock);
}
if (ktrpoint(KTR_PSIG)) {
if (p->p_emul->e_ktrpsig)
p->p_emul->e_ktrpsig(signo, action, mask, &ksi);
else
ktrpsig(signo, action, mask, &ksi);
}
}
void
eventswitchchild(struct proc *p, int code, int pe_report_event)
{
mutex_enter(&proc_lock);
mutex_enter(p->p_lock);
if ((p->p_slflag & (PSL_TRACED|PSL_TRACEDCHILD)) !=
(PSL_TRACED|PSL_TRACEDCHILD)) {
mutex_exit(p->p_lock);
mutex_exit(&proc_lock);
return;
}
eventswitch(code, pe_report_event, p->p_oppid);
}
/*
* Stop the current process and switch away when being stopped or traced.
*/
static void
sigswitch(int ppmask, int signo, bool proc_lock_held)
{
struct lwp *l = curlwp;
struct proc *p = l->l_proc;
if (proc_lock_held) {
KASSERT(mutex_owned(&proc_lock));
} else {
KASSERT(!mutex_owned(&proc_lock));
}
/*
* On entry we know that the process needs to stop. If it's
* the result of a 'sideways' stop signal that has been sourced
* through issignal(), then stop other LWPs in the process too.
*/
if (p->p_stat == SACTIVE && (p->p_sflag & PS_STOPPING) == 0) {
KASSERT(signo != 0);
proc_stop(p, signo);
KASSERT(p->p_nrlwps > 0);
}
/*
* If we are the last live LWP, and the stop was a result of
* a new signal, then signal the parent.
*/
if ((p->p_sflag & PS_STOPPING) != 0) {
if (!proc_lock_held && !mutex_tryenter(&proc_lock)) {
mutex_exit(p->p_lock);
mutex_enter(&proc_lock);
mutex_enter(p->p_lock);
}
if (p->p_nrlwps == 1 && (p->p_sflag & PS_STOPPING) != 0) {
/*
* Note that proc_stop_done() can drop
* p->p_lock briefly.
*/
proc_stop_done(p, ppmask);
}
/*
* Check for a signal from the debugger.
*/
static int
sigchecktrace(void)
{
struct lwp *l = curlwp;
struct proc *p = l->l_proc;
int signo;
KASSERT(mutex_owned(p->p_lock));
/* If there's a pending SIGKILL, process it immediately. */
if (sigismember(&p->p_sigpend.sp_set, SIGKILL))
return 0;
/*
* If we are no longer being traced, or the parent didn't
* give us a signal, or we're stopping, look for more signals.
*/
if ((p->p_slflag & PSL_TRACED) == 0 || p->p_xsig == 0 ||
(p->p_sflag & PS_STOPPING) != 0)
return 0;
/*
* If the new signal is being masked, look for other signals.
* `p->p_sigctx.ps_siglist |= mask' is done in setrunnable().
*/
signo = p->p_xsig;
p->p_xsig = 0;
if (sigismember(&l->l_sigmask, signo)) {
signo = 0;
}
return signo;
}
/*
* If the current process has received a signal (should be caught or cause
* termination, should interrupt current syscall), return the signal number.
*
* Stop signals with default action are processed immediately, then cleared;
* they aren't returned. This is checked after each entry to the system for
* a syscall or trap.
*
* We will also return -1 if the process is exiting and the current LWP must
* follow suit.
*/
int
issignal(struct lwp *l)
{
struct proc *p;
int siglwp, signo, prop;
sigpend_t *sp;
sigset_t ss;
bool traced;
for (;;) {
/* Discard any signals that we have decided not to take. */
if (signo != 0) {
(void)sigget(sp, NULL, signo, NULL);
}
/*
* If the process is stopped/stopping, then stop ourselves
* now that we're on the kernel/userspace boundary. When
* we awaken, check for a signal from the debugger.
*/
if (p->p_stat == SSTOP || (p->p_sflag & PS_STOPPING) != 0) {
sigswitch_unlock_and_switch_away(l);
mutex_enter(p->p_lock);
continue;
} else if (p->p_stat == SACTIVE)
signo = sigchecktrace();
else
signo = 0;
/* Signals from the debugger are "out of band". */
sp = NULL;
/*
* If the debugger didn't provide a signal, find a pending
* signal from our set. Check per-LWP signals first, and
* then per-process.
*/
if (signo == 0) {
sp = &l->l_sigpend;
ss = sp->sp_set;
siglwp = l->l_lid;
if ((p->p_lflag & PL_PPWAIT) != 0)
sigminusset(&vforksigmask, &ss);
sigminusset(&l->l_sigmask, &ss);
if ((signo = firstsig(&ss)) == 0) {
sp = &p->p_sigpend;
ss = sp->sp_set;
siglwp = 0;
if ((p->p_lflag & PL_PPWAIT) != 0)
sigminusset(&vforksigmask, &ss);
sigminusset(&l->l_sigmask, &ss);
if ((signo = firstsig(&ss)) == 0) {
/*
* No signal pending - clear the
* indicator and bail out.
*/
lwp_lock(l);
l->l_flag &= ~LW_PENDSIG;
lwp_unlock(l);
sp = NULL;
break;
}
}
}
if (sp) {
/* Overwrite process' signal context to correspond
* to the currently reported LWP. This is necessary
* for PT_GET_SIGINFO to report the correct signal when
* multiple LWPs have pending signals. We do this only
* when the signal comes from the queue, for signals
* created by the debugger we assume it set correct
* siginfo.
*/
ksiginfo_t *ksi = TAILQ_FIRST(&sp->sp_info);
if (ksi) {
p->p_sigctx.ps_lwp = ksi->ksi_lid;
p->p_sigctx.ps_info = ksi->ksi_info;
} else {
p->p_sigctx.ps_lwp = siglwp;
memset(&p->p_sigctx.ps_info, 0,
sizeof(p->p_sigctx.ps_info));
p->p_sigctx.ps_info._signo = signo;
p->p_sigctx.ps_info._code = SI_NOINFO;
}
}
/*
* We should see pending but ignored signals only if
* we are being traced.
*/
if (sigismember(&p->p_sigctx.ps_sigignore, signo) &&
!traced) {
/* Discard the signal. */
continue;
}
/*
* If traced, always stop, and stay stopped until released
* by the debugger. If the our parent is our debugger waiting
* for us and we vforked, don't hang as we could deadlock.
*/
if (traced && signo != SIGKILL &&
!(ISSET(p->p_lflag, PL_PPWAIT) &&
(p->p_pptr == p->p_opptr))) {
/*
* Take the signal, but don't remove it from the
* siginfo queue, because the debugger can send
* it later.
*/
if (sp)
sigdelset(&sp->sp_set, signo);
p->p_xsig = signo;
/* Handling of signal trace */
sigswitch(0, signo, false);
mutex_enter(p->p_lock);
/* Check for a signal from the debugger. */
if ((signo = sigchecktrace()) == 0)
continue;
/* Signals from the debugger are "out of band". */
sp = NULL;
}
prop = sigprop[signo];
/*
* Decide whether the signal should be returned.
*/
switch ((long)SIGACTION(p, signo).sa_handler) {
case (long)SIG_DFL:
/*
* Don't take default actions on system processes.
*/
if (p->p_pid <= 1) {
#ifdef DIAGNOSTIC
/*
* Are you sure you want to ignore SIGSEGV
* in init? XXX
*/
printf_nolog("Process (pid %d) got sig %d\n",
p->p_pid, signo);
#endif
continue;
}
/*
* If there is a pending stop signal to process with
* default action, stop here, then clear the signal.
* However, if process is member of an orphaned
* process group, ignore tty stop signals.
*/
if (prop & SA_STOP) {
/*
* XXX Don't hold proc_lock for p_lflag,
* but it's not a big deal.
*/
if ((traced &&
!(ISSET(p->p_lflag, PL_PPWAIT) &&
(p->p_pptr == p->p_opptr))) ||
((p->p_lflag & PL_ORPHANPG) != 0 &&
prop & SA_TTYSTOP)) {
/* Ignore the signal. */
continue;
}
/* Take the signal. */
(void)sigget(sp, NULL, signo, NULL);
p->p_xsig = signo;
p->p_sflag &= ~PS_CONTINUED;
signo = 0;
sigswitch(PS_NOCLDSTOP, p->p_xsig, false);
mutex_enter(p->p_lock);
} else if (prop & SA_IGNORE) {
/*
* Except for SIGCONT, shouldn't get here.
* Default action is to ignore; drop it.
*/
continue;
}
break;
case (long)SIG_IGN:
#ifdef DEBUG_ISSIGNAL
/*
* Masking above should prevent us ever trying
* to take action on an ignored signal other
* than SIGCONT, unless process is traced.
*/
if ((prop & SA_CONT) == 0 && !traced)
printf_nolog("issignal\n");
#endif
continue;
default:
/*
* This signal has an action, let postsig() process
* it.
*/
break;
}
break;
}
l->l_sigpendset = sp;
return signo;
}
/*
* Take the action for the specified signal
* from the current set of pending signals.
*/
void
postsig(int signo)
{
struct lwp *l;
struct proc *p;
struct sigacts *ps;
sig_t action;
sigset_t *returnmask;
ksiginfo_t ksi;
/*
* Set the new mask value and also defer further occurrences of this
* signal.
*
* Special case: user has done a sigsuspend. Here the current mask is
* not of interest, but rather the mask from before the sigsuspend is
* what we want restored after the signal processing is completed.
*/
if (l->l_sigrestore) {
returnmask = &l->l_sigoldmask;
l->l_sigrestore = 0;
} else
returnmask = &l->l_sigmask;
/*
* Commit to taking the signal before releasing the mutex.
*/
action = SIGACTION_PS(ps, signo).sa_handler;
l->l_ru.ru_nsignals++;
if (l->l_sigpendset == NULL) {
/* From the debugger */
if (p->p_sigctx.ps_faked &&
signo == p->p_sigctx.ps_info._signo) {
KSI_INIT(&ksi);
ksi.ksi_info = p->p_sigctx.ps_info;
ksi.ksi_lid = p->p_sigctx.ps_lwp;
p->p_sigctx.ps_faked = false;
} else {
if (!siggetinfo(&l->l_sigpend, &ksi, signo))
(void)siggetinfo(&p->p_sigpend, &ksi, signo);
}
} else
sigget(l->l_sigpendset, &ksi, signo, NULL);
if (ktrpoint(KTR_PSIG)) {
mutex_exit(p->p_lock);
if (p->p_emul->e_ktrpsig)
p->p_emul->e_ktrpsig(signo, action,
returnmask, &ksi);
else
ktrpsig(signo, action, returnmask, &ksi);
mutex_enter(p->p_lock);
}
if (action == SIG_DFL) {
/*
* Default action, where the default is to kill
* the process. (Other cases were ignored above.)
*/
sigexit(l, signo);
return;
}
/*
* If we get here, the signal must be caught.
*/
#ifdef DIAGNOSTIC
if (action == SIG_IGN || sigismember(&l->l_sigmask, signo))
panic("postsig action");
#endif
kpsendsig(l, &ksi, returnmask);
}
/*
* sendsig:
*
* Default signal delivery method for NetBSD.
*/
void
sendsig(const struct ksiginfo *ksi, const sigset_t *mask)
{
struct sigacts *sa;
int sig;
sig = ksi->ksi_signo;
sa = curproc->p_sigacts;
switch (sa->sa_sigdesc[sig].sd_vers) {
case __SIGTRAMP_SIGCODE_VERSION:
#ifdef __HAVE_STRUCT_SIGCONTEXT
case __SIGTRAMP_SIGCONTEXT_VERSION_MIN ...
__SIGTRAMP_SIGCONTEXT_VERSION_MAX:
/* Compat for 1.6 and earlier. */
MODULE_HOOK_CALL_VOID(sendsig_sigcontext_16_hook, (ksi, mask),
break);
return;
#endif /* __HAVE_STRUCT_SIGCONTEXT */
case __SIGTRAMP_SIGINFO_VERSION_MIN ...
__SIGTRAMP_SIGINFO_VERSION_MAX:
sendsig_siginfo(ksi, mask);
return;
default:
break;
}
printf("sendsig: bad version %d\n", sa->sa_sigdesc[sig].sd_vers);
sigexit(curlwp, SIGILL);
}
/*
* sendsig_reset:
*
* Reset the signal action. Called from emulation specific sendsig()
* before unlocking to deliver the signal.
*/
void
sendsig_reset(struct lwp *l, int signo)
{
struct proc *p = l->l_proc;
struct sigacts *ps = p->p_sigacts;
/*
* Kill the current process for stated reason.
*/
void
killproc(struct proc *p, const char *why)
{
KASSERT(mutex_owned(&proc_lock));
log(LOG_ERR, "pid %d was killed: %s\n", p->p_pid, why);
uprintf_locked("sorry, pid %d was killed: %s\n", p->p_pid, why);
psignal(p, SIGKILL);
}
/*
* Force the current process to exit with the specified signal, dumping core
* if appropriate. We bypass the normal tests for masked and caught
* signals, allowing unrecoverable failures to terminate the process without
* changing signal state. Mark the accounting record with the signal
* termination. If dumping core, save the signal number for the debugger.
* Calls exit and does not return.
*/
void
sigexit(struct lwp *l, int signo)
{
int exitsig, error, docore;
struct proc *p;
struct lwp *t;
/*
* Don't permit coredump() multiple times in the same process.
* Call back into sigexit, where we will be suspended until
* the deed is done. Note that this is a recursive call, but
* LW_WCORE will prevent us from coming back this way.
*/
if ((p->p_sflag & PS_WCORE) != 0) {
lwp_lock(l);
l->l_flag |= (LW_WCORE | LW_WEXIT | LW_WSUSPEND);
lwp_need_userret(l);
lwp_unlock(l);
mutex_exit(p->p_lock);
lwp_userret(l);
panic("sigexit 1");
/* NOTREACHED */
}
/* If process is already on the way out, then bail now. */
if ((p->p_sflag & PS_WEXIT) != 0) {
mutex_exit(p->p_lock);
lwp_exit(l);
panic("sigexit 2");
/* NOTREACHED */
}
/*
* Prepare all other LWPs for exit. If dumping core, suspend them
* so that their registers are available long enough to be dumped.
*/
if ((docore = (sigprop[signo] & SA_CORE)) != 0) {
p->p_sflag |= PS_WCORE;
for (;;) {
LIST_FOREACH(t, &p->p_lwps, l_sibling) {
lwp_lock(t);
if (t == l) {
t->l_flag &=
~(LW_WSUSPEND | LW_DBGSUSPEND);
lwp_unlock(t);
continue;
}
t->l_flag |= (LW_WCORE | LW_WEXIT);
lwp_need_userret(t);
lwp_suspend(l, t);
}
if (p->p_nrlwps == 1)
break;
/*
* Kick any LWPs sitting in lwp_wait1(), and wait
* for everyone else to stop before proceeding.
*/
p->p_nlwpwait++;
cv_broadcast(&p->p_lwpcv);
cv_wait(&p->p_lwpcv, p->p_lock);
p->p_nlwpwait--;
}
}
/*
* Put process 'p' into the stopped state and optionally, notify the parent.
*/
void
proc_stop(struct proc *p, int signo)
{
struct lwp *l;
KASSERT(mutex_owned(p->p_lock));
/*
* First off, set the stopping indicator and bring all sleeping
* LWPs to a halt so they are included in p->p_nrlwps. We mustn't
* unlock between here and the p->p_nrlwps check below.
*/
p->p_sflag |= PS_STOPPING;
membar_producer();
proc_stop_lwps(p);
/*
* If there are no LWPs available to take the signal, then we
* signal the parent process immediately. Otherwise, the last
* LWP to stop will take care of it.
*/
if (p->p_nrlwps == 0) {
proc_stop_done(p, PS_NOCLDSTOP);
} else {
/*
* Have the remaining LWPs come to a halt, and trigger
* proc_stop_callout() to ensure that they do.
*/
LIST_FOREACH(l, &p->p_lwps, l_sibling) {
sigpost(l, SIG_DFL, SA_STOP, signo);
}
callout_schedule(&proc_stop_ch, 1);
}
}
/*
* When stopping a process, we do not immediately set sleeping LWPs stopped,
* but wait for them to come to a halt at the kernel-user boundary. This is
* to allow LWPs to release any locks that they may hold before stopping.
*
* Non-interruptable sleeps can be long, and there is the potential for an
* LWP to begin sleeping interruptably soon after the process has been set
* stopping (PS_STOPPING). These LWPs will not notice that the process is
* stopping, and so complete halt of the process and the return of status
* information to the parent could be delayed indefinitely.
*
* To handle this race, proc_stop_callout() runs once per tick while there
* are stopping processes in the system. It sets LWPs that are sleeping
* interruptably into the LSSTOP state.
*
* Note that we are not concerned about keeping all LWPs stopped while the
* process is stopped: stopped LWPs can awaken briefly to handle signals.
* What we do need to ensure is that all LWPs in a stopping process have
* stopped at least once, so that notification can be sent to the parent
* process.
*/
static void
proc_stop_callout(void *cookie)
{
bool more, restart;
struct proc *p;
if ((p->p_sflag & PS_STOPPING) == 0) {
mutex_exit(p->p_lock);
continue;
}
/* Stop any LWPs sleeping interruptably. */
proc_stop_lwps(p);
if (p->p_nrlwps == 0) {
/*
* We brought the process to a halt.
* Mark it as stopped and notify the
* parent.
*
* Note that proc_stop_done() will
* drop p->p_lock briefly.
* Arrange to restart and check
* all processes again.
*/
restart = true;
proc_stop_done(p, PS_NOCLDSTOP);
} else
more = true;
mutex_exit(p->p_lock);
if (restart)
break;
}
mutex_exit(&proc_lock);
} while (restart);
/*
* If we noted processes that are stopping but still have
* running LWPs, then arrange to check again in 1 tick.
*/
if (more)
callout_schedule(&proc_stop_ch, 1);
}
/*
* Given a process in state SSTOP, set the state back to SACTIVE and
* move LSSTOP'd LWPs to LSSLEEP or make them runnable.
*/
void
proc_unstop(struct proc *p)
{
struct lwp *l;
int sig;
for (i = 0; i < sy_narg; i++)
ksi.ksi_args[i] = args[i];
mutex_enter(p->p_lock);
repeat:
/*
* If we are exiting, demise now.
*
* This avoids notifying tracer and deadlocking.
*/
if (__predict_false(ISSET(p->p_sflag, PS_WEXIT))) {
mutex_exit(p->p_lock);
lwp_exit(l);
panic("proc_stoptrace");
/* NOTREACHED */
}
/*
* If there's a pending SIGKILL process it immediately.
*/
if (p->p_xsig == SIGKILL ||
sigismember(&p->p_sigpend.sp_set, SIGKILL)) {
mutex_exit(p->p_lock);
return;
}
/*
* If we are no longer traced, abandon this event signal.
*
* This avoids killing a process after detaching the debugger.
*/
if (__predict_false(!ISSET(p->p_slflag, PSL_TRACED))) {
mutex_exit(p->p_lock);
return;
}
/*
* The process is already stopping.
*/
if ((p->p_sflag & PS_STOPPING) != 0) {
sigswitch_unlock_and_switch_away(l);
mutex_enter(p->p_lock);
goto repeat;
}
/*
* 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)
{
