freebsd-dev/sys/kern/kern_exit.c
Konstantin Belousov aca4bb9112 Do not leak mount references for dying threads.
Thread might create a condition for delayed SU cleanup, which creates
a reference to the mount point in td_su, but exit without returning
through userret(), e.g. when terminating due to single-threading or
process exit.  In this case, td_su reference is not dropped and mount
point cannot be freed.

Handle the situation by clearing td_su also in the thread destructor
and in exit1().  softdep_ast_cleanup() has to receive the thread as
argument, since e.g. thread destructor is executed in different
context.

Reported and tested by:	pho
Sponsored by:	The FreeBSD Foundation
MFC after:	2 weeks
2017-02-25 10:38:18 +00:00

1322 lines
33 KiB
C

/*-
* 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_exit.c 8.7 (Berkeley) 2/12/94
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include "opt_compat.h"
#include "opt_ktrace.h"
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/sysproto.h>
#include <sys/capsicum.h>
#include <sys/eventhandler.h>
#include <sys/kernel.h>
#include <sys/malloc.h>
#include <sys/lock.h>
#include <sys/mutex.h>
#include <sys/proc.h>
#include <sys/procdesc.h>
#include <sys/pioctl.h>
#include <sys/jail.h>
#include <sys/tty.h>
#include <sys/wait.h>
#include <sys/vmmeter.h>
#include <sys/vnode.h>
#include <sys/racct.h>
#include <sys/resourcevar.h>
#include <sys/sbuf.h>
#include <sys/signalvar.h>
#include <sys/sched.h>
#include <sys/sx.h>
#include <sys/syscallsubr.h>
#include <sys/syslog.h>
#include <sys/ptrace.h>
#include <sys/acct.h> /* for acct_process() function prototype */
#include <sys/filedesc.h>
#include <sys/sdt.h>
#include <sys/shm.h>
#include <sys/sem.h>
#include <sys/umtx.h>
#ifdef KTRACE
#include <sys/ktrace.h>
#endif
#include <security/audit/audit.h>
#include <security/mac/mac_framework.h>
#include <vm/vm.h>
#include <vm/vm_extern.h>
#include <vm/vm_param.h>
#include <vm/pmap.h>
#include <vm/vm_map.h>
#include <vm/vm_page.h>
#include <vm/uma.h>
#include <vm/vm_domain.h>
#ifdef KDTRACE_HOOKS
#include <sys/dtrace_bsd.h>
dtrace_execexit_func_t dtrace_fasttrap_exit;
#endif
SDT_PROVIDER_DECLARE(proc);
SDT_PROBE_DEFINE1(proc, , , exit, "int");
/* Hook for NFS teardown procedure. */
void (*nlminfo_release_p)(struct proc *p);
struct proc *
proc_realparent(struct proc *child)
{
struct proc *p, *parent;
sx_assert(&proctree_lock, SX_LOCKED);
if ((child->p_treeflag & P_TREE_ORPHANED) == 0) {
if (child->p_oppid == 0 ||
child->p_pptr->p_pid == child->p_oppid)
parent = child->p_pptr;
else
parent = initproc;
return (parent);
}
for (p = child; (p->p_treeflag & P_TREE_FIRST_ORPHAN) == 0;) {
/* Cannot use LIST_PREV(), since the list head is not known. */
p = __containerof(p->p_orphan.le_prev, struct proc,
p_orphan.le_next);
KASSERT((p->p_treeflag & P_TREE_ORPHANED) != 0,
("missing P_ORPHAN %p", p));
}
parent = __containerof(p->p_orphan.le_prev, struct proc,
p_orphans.lh_first);
return (parent);
}
void
reaper_abandon_children(struct proc *p, bool exiting)
{
struct proc *p1, *p2, *ptmp;
sx_assert(&proctree_lock, SX_LOCKED);
KASSERT(p != initproc, ("reaper_abandon_children for initproc"));
if ((p->p_treeflag & P_TREE_REAPER) == 0)
return;
p1 = p->p_reaper;
LIST_FOREACH_SAFE(p2, &p->p_reaplist, p_reapsibling, ptmp) {
LIST_REMOVE(p2, p_reapsibling);
p2->p_reaper = p1;
p2->p_reapsubtree = p->p_reapsubtree;
LIST_INSERT_HEAD(&p1->p_reaplist, p2, p_reapsibling);
if (exiting && p2->p_pptr == p) {
PROC_LOCK(p2);
proc_reparent(p2, p1);
PROC_UNLOCK(p2);
}
}
KASSERT(LIST_EMPTY(&p->p_reaplist), ("p_reaplist not empty"));
p->p_treeflag &= ~P_TREE_REAPER;
}
static void
clear_orphan(struct proc *p)
{
struct proc *p1;
sx_assert(&proctree_lock, SA_XLOCKED);
if ((p->p_treeflag & P_TREE_ORPHANED) == 0)
return;
if ((p->p_treeflag & P_TREE_FIRST_ORPHAN) != 0) {
p1 = LIST_NEXT(p, p_orphan);
if (p1 != NULL)
p1->p_treeflag |= P_TREE_FIRST_ORPHAN;
p->p_treeflag &= ~P_TREE_FIRST_ORPHAN;
}
LIST_REMOVE(p, p_orphan);
p->p_treeflag &= ~P_TREE_ORPHANED;
}
/*
* exit -- death of process.
*/
void
sys_sys_exit(struct thread *td, struct sys_exit_args *uap)
{
exit1(td, uap->rval, 0);
/* NOTREACHED */
}
/*
* Exit: deallocate address space and other resources, change proc state to
* zombie, and unlink proc from allproc and parent's lists. Save exit status
* and rusage for wait(). Check for child processes and orphan them.
*/
void
exit1(struct thread *td, int rval, int signo)
{
struct proc *p, *nq, *q, *t;
struct thread *tdt;
mtx_assert(&Giant, MA_NOTOWNED);
KASSERT(rval == 0 || signo == 0, ("exit1 rv %d sig %d", rval, signo));
p = td->td_proc;
/*
* XXX in case we're rebooting we just let init die in order to
* work around an unsolved stack overflow seen very late during
* shutdown on sparc64 when the gmirror worker process exists.
*/
if (p == initproc && rebooting == 0) {
printf("init died (signal %d, exit %d)\n", signo, rval);
panic("Going nowhere without my init!");
}
/*
* Deref SU mp, since the thread does not return to userspace.
*/
td_softdep_cleanup(td);
/*
* MUST abort all other threads before proceeding past here.
*/
PROC_LOCK(p);
/*
* First check if some other thread or external request got
* here before us. If so, act appropriately: exit or suspend.
* We must ensure that stop requests are handled before we set
* P_WEXIT.
*/
thread_suspend_check(0);
while (p->p_flag & P_HADTHREADS) {
/*
* Kill off the other threads. This requires
* some co-operation from other parts of the kernel
* so it may not be instantaneous. With this state set
* any thread entering the kernel from userspace will
* thread_exit() in trap(). Any thread attempting to
* sleep will return immediately with EINTR or EWOULDBLOCK
* which will hopefully force them to back out to userland
* freeing resources as they go. Any thread attempting
* to return to userland will thread_exit() from userret().
* thread_exit() will unsuspend us when the last of the
* other threads exits.
* If there is already a thread singler after resumption,
* calling thread_single will fail; in that case, we just
* re-check all suspension request, the thread should
* either be suspended there or exit.
*/
if (!thread_single(p, SINGLE_EXIT))
/*
* All other activity in this process is now
* stopped. Threading support has been turned
* off.
*/
break;
/*
* Recheck for new stop or suspend requests which
* might appear while process lock was dropped in
* thread_single().
*/
thread_suspend_check(0);
}
KASSERT(p->p_numthreads == 1,
("exit1: proc %p exiting with %d threads", p, p->p_numthreads));
racct_sub(p, RACCT_NTHR, 1);
/* Let event handler change exit status */
p->p_xexit = rval;
p->p_xsig = signo;
/*
* Wakeup anyone in procfs' PIOCWAIT. They should have a hold
* on our vmspace, so we should block below until they have
* released their reference to us. Note that if they have
* requested S_EXIT stops we will block here until they ack
* via PIOCCONT.
*/
_STOPEVENT(p, S_EXIT, 0);
/*
* Ignore any pending request to stop due to a stop signal.
* Once P_WEXIT is set, future requests will be ignored as
* well.
*/
p->p_flag &= ~P_STOPPED_SIG;
KASSERT(!P_SHOULDSTOP(p), ("exiting process is stopped"));
/*
* Note that we are exiting and do another wakeup of anyone in
* PIOCWAIT in case they aren't listening for S_EXIT stops or
* decided to wait again after we told them we are exiting.
*/
p->p_flag |= P_WEXIT;
wakeup(&p->p_stype);
/*
* Wait for any processes that have a hold on our vmspace to
* release their reference.
*/
while (p->p_lock > 0)
msleep(&p->p_lock, &p->p_mtx, PWAIT, "exithold", 0);
PROC_UNLOCK(p);
/* Drain the limit callout while we don't have the proc locked */
callout_drain(&p->p_limco);
#ifdef AUDIT
/*
* The Sun BSM exit token contains two components: an exit status as
* passed to exit(), and a return value to indicate what sort of exit
* it was. The exit status is WEXITSTATUS(rv), but it's not clear
* what the return value is.
*/
AUDIT_ARG_EXIT(rval, 0);
AUDIT_SYSCALL_EXIT(0, td);
#endif
/* Are we a task leader with peers? */
if (p->p_peers != NULL && p == p->p_leader) {
mtx_lock(&ppeers_lock);
q = p->p_peers;
while (q != NULL) {
PROC_LOCK(q);
kern_psignal(q, SIGKILL);
PROC_UNLOCK(q);
q = q->p_peers;
}
while (p->p_peers != NULL)
msleep(p, &ppeers_lock, PWAIT, "exit1", 0);
mtx_unlock(&ppeers_lock);
}
/*
* Check if any loadable modules need anything done at process exit.
* E.g. SYSV IPC stuff.
* Event handler could change exit status.
* XXX what if one of these generates an error?
*/
EVENTHANDLER_INVOKE(process_exit, p);
/*
* If parent is waiting for us to exit or exec,
* P_PPWAIT is set; we will wakeup the parent below.
*/
PROC_LOCK(p);
stopprofclock(p);
p->p_flag &= ~(P_TRACED | P_PPWAIT | P_PPTRACE);
p->p_ptevents = 0;
/*
* Stop the real interval timer. If the handler is currently
* executing, prevent it from rearming itself and let it finish.
*/
if (timevalisset(&p->p_realtimer.it_value) &&
_callout_stop_safe(&p->p_itcallout, CS_EXECUTING, NULL) == 0) {
timevalclear(&p->p_realtimer.it_interval);
msleep(&p->p_itcallout, &p->p_mtx, PWAIT, "ritwait", 0);
KASSERT(!timevalisset(&p->p_realtimer.it_value),
("realtime timer is still armed"));
}
PROC_UNLOCK(p);
umtx_thread_exit(td);
/*
* Reset any sigio structures pointing to us as a result of
* F_SETOWN with our pid.
*/
funsetownlst(&p->p_sigiolst);
/*
* If this process has an nlminfo data area (for lockd), release it
*/
if (nlminfo_release_p != NULL && p->p_nlminfo != NULL)
(*nlminfo_release_p)(p);
/*
* Close open files and release open-file table.
* This may block!
*/
fdescfree(td);
/*
* If this thread tickled GEOM, we need to wait for the giggling to
* stop before we return to userland
*/
if (td->td_pflags & TDP_GEOM)
g_waitidle();
/*
* Remove ourself from our leader's peer list and wake our leader.
*/
if (p->p_leader->p_peers != NULL) {
mtx_lock(&ppeers_lock);
if (p->p_leader->p_peers != NULL) {
q = p->p_leader;
while (q->p_peers != p)
q = q->p_peers;
q->p_peers = p->p_peers;
wakeup(p->p_leader);
}
mtx_unlock(&ppeers_lock);
}
vmspace_exit(td);
killjobc();
(void)acct_process(td);
#ifdef KTRACE
ktrprocexit(td);
#endif
/*
* Release reference to text vnode
*/
if (p->p_textvp != NULL) {
vrele(p->p_textvp);
p->p_textvp = NULL;
}
/*
* Release our limits structure.
*/
lim_free(p->p_limit);
p->p_limit = NULL;
tidhash_remove(td);
/*
* Remove proc from allproc queue and pidhash chain.
* Place onto zombproc. Unlink from parent's child list.
*/
sx_xlock(&allproc_lock);
LIST_REMOVE(p, p_list);
LIST_INSERT_HEAD(&zombproc, p, p_list);
LIST_REMOVE(p, p_hash);
sx_xunlock(&allproc_lock);
/*
* Call machine-dependent code to release any
* machine-dependent resources other than the address space.
* The address space is released by "vmspace_exitfree(p)" in
* vm_waitproc().
*/
cpu_exit(td);
WITNESS_WARN(WARN_PANIC, NULL, "process (pid %d) exiting", p->p_pid);
/*
* Reparent all children processes:
* - traced ones to the original parent (or init if we are that parent)
* - the rest to init
*/
sx_xlock(&proctree_lock);
q = LIST_FIRST(&p->p_children);
if (q != NULL) /* only need this if any child is S_ZOMB */
wakeup(q->p_reaper);
for (; q != NULL; q = nq) {
nq = LIST_NEXT(q, p_sibling);
PROC_LOCK(q);
q->p_sigparent = SIGCHLD;
if (!(q->p_flag & P_TRACED)) {
proc_reparent(q, q->p_reaper);
if (q->p_state == PRS_ZOMBIE) {
PROC_LOCK(q->p_reaper);
pksignal(q->p_reaper, SIGCHLD, q->p_ksi);
PROC_UNLOCK(q->p_reaper);
}
} else {
/*
* Traced processes are killed since their existence
* means someone is screwing up.
*/
t = proc_realparent(q);
if (t == p) {
proc_reparent(q, q->p_reaper);
} else {
PROC_LOCK(t);
proc_reparent(q, t);
PROC_UNLOCK(t);
}
/*
* Since q was found on our children list, the
* proc_reparent() call moved q to the orphan
* list due to present P_TRACED flag. Clear
* orphan link for q now while q is locked.
*/
clear_orphan(q);
q->p_flag &= ~(P_TRACED | P_STOPPED_TRACE);
q->p_flag2 &= ~P2_PTRACE_FSTP;
q->p_ptevents = 0;
FOREACH_THREAD_IN_PROC(q, tdt) {
tdt->td_dbgflags &= ~(TDB_SUSPEND | TDB_XSIG |
TDB_FSTP);
}
kern_psignal(q, SIGKILL);
}
PROC_UNLOCK(q);
}
/*
* Also get rid of our orphans.
*/
while ((q = LIST_FIRST(&p->p_orphans)) != NULL) {
PROC_LOCK(q);
CTR2(KTR_PTRACE, "exit: pid %d, clearing orphan %d", p->p_pid,
q->p_pid);
clear_orphan(q);
PROC_UNLOCK(q);
}
/* Save exit status. */
PROC_LOCK(p);
p->p_xthread = td;
/* Tell the prison that we are gone. */
prison_proc_free(p->p_ucred->cr_prison);
#ifdef KDTRACE_HOOKS
/*
* Tell the DTrace fasttrap provider about the exit if it
* has declared an interest.
*/
if (dtrace_fasttrap_exit)
dtrace_fasttrap_exit(p);
#endif
/*
* Notify interested parties of our demise.
*/
KNOTE_LOCKED(p->p_klist, NOTE_EXIT);
#ifdef KDTRACE_HOOKS
int reason = CLD_EXITED;
if (WCOREDUMP(signo))
reason = CLD_DUMPED;
else if (WIFSIGNALED(signo))
reason = CLD_KILLED;
SDT_PROBE1(proc, , , exit, reason);
#endif
/*
* If this is a process with a descriptor, we may not need to deliver
* a signal to the parent. proctree_lock is held over
* procdesc_exit() to serialize concurrent calls to close() and
* exit().
*/
if (p->p_procdesc == NULL || procdesc_exit(p)) {
/*
* Notify parent that we're gone. If parent has the
* PS_NOCLDWAIT flag set, or if the handler is set to SIG_IGN,
* notify process 1 instead (and hope it will handle this
* situation).
*/
PROC_LOCK(p->p_pptr);
mtx_lock(&p->p_pptr->p_sigacts->ps_mtx);
if (p->p_pptr->p_sigacts->ps_flag &
(PS_NOCLDWAIT | PS_CLDSIGIGN)) {
struct proc *pp;
mtx_unlock(&p->p_pptr->p_sigacts->ps_mtx);
pp = p->p_pptr;
PROC_UNLOCK(pp);
proc_reparent(p, p->p_reaper);
p->p_sigparent = SIGCHLD;
PROC_LOCK(p->p_pptr);
/*
* Notify parent, so in case he was wait(2)ing or
* executing waitpid(2) with our pid, he will
* continue.
*/
wakeup(pp);
} else
mtx_unlock(&p->p_pptr->p_sigacts->ps_mtx);
if (p->p_pptr == p->p_reaper || p->p_pptr == initproc)
childproc_exited(p);
else if (p->p_sigparent != 0) {
if (p->p_sigparent == SIGCHLD)
childproc_exited(p);
else /* LINUX thread */
kern_psignal(p->p_pptr, p->p_sigparent);
}
} else
PROC_LOCK(p->p_pptr);
sx_xunlock(&proctree_lock);
/*
* The state PRS_ZOMBIE prevents other proesses from sending
* signal to the process, to avoid memory leak, we free memory
* for signal queue at the time when the state is set.
*/
sigqueue_flush(&p->p_sigqueue);
sigqueue_flush(&td->td_sigqueue);
/*
* We have to wait until after acquiring all locks before
* changing p_state. We need to avoid all possible context
* switches (including ones from blocking on a mutex) while
* marked as a zombie. We also have to set the zombie state
* before we release the parent process' proc lock to avoid
* a lost wakeup. So, we first call wakeup, then we grab the
* sched lock, update the state, and release the parent process'
* proc lock.
*/
wakeup(p->p_pptr);
cv_broadcast(&p->p_pwait);
sched_exit(p->p_pptr, td);
PROC_SLOCK(p);
p->p_state = PRS_ZOMBIE;
PROC_UNLOCK(p->p_pptr);
/*
* Save our children's rusage information in our exit rusage.
*/
PROC_STATLOCK(p);
ruadd(&p->p_ru, &p->p_rux, &p->p_stats->p_cru, &p->p_crux);
PROC_STATUNLOCK(p);
/*
* Make sure the scheduler takes this thread out of its tables etc.
* This will also release this thread's reference to the ucred.
* Other thread parts to release include pcb bits and such.
*/
thread_exit();
}
#ifndef _SYS_SYSPROTO_H_
struct abort2_args {
char *why;
int nargs;
void **args;
};
#endif
int
sys_abort2(struct thread *td, struct abort2_args *uap)
{
struct proc *p = td->td_proc;
struct sbuf *sb;
void *uargs[16];
int error, i, sig;
/*
* Do it right now so we can log either proper call of abort2(), or
* note, that invalid argument was passed. 512 is big enough to
* handle 16 arguments' descriptions with additional comments.
*/
sb = sbuf_new(NULL, NULL, 512, SBUF_FIXEDLEN);
sbuf_clear(sb);
sbuf_printf(sb, "%s(pid %d uid %d) aborted: ",
p->p_comm, p->p_pid, td->td_ucred->cr_uid);
/*
* Since we can't return from abort2(), send SIGKILL in cases, where
* abort2() was called improperly
*/
sig = SIGKILL;
/* Prevent from DoSes from user-space. */
if (uap->nargs < 0 || uap->nargs > 16)
goto out;
if (uap->nargs > 0) {
if (uap->args == NULL)
goto out;
error = copyin(uap->args, uargs, uap->nargs * sizeof(void *));
if (error != 0)
goto out;
}
/*
* Limit size of 'reason' string to 128. Will fit even when
* maximal number of arguments was chosen to be logged.
*/
if (uap->why != NULL) {
error = sbuf_copyin(sb, uap->why, 128);
if (error < 0)
goto out;
} else {
sbuf_printf(sb, "(null)");
}
if (uap->nargs > 0) {
sbuf_printf(sb, "(");
for (i = 0;i < uap->nargs; i++)
sbuf_printf(sb, "%s%p", i == 0 ? "" : ", ", uargs[i]);
sbuf_printf(sb, ")");
}
/*
* Final stage: arguments were proper, string has been
* successfully copied from userspace, and copying pointers
* from user-space succeed.
*/
sig = SIGABRT;
out:
if (sig == SIGKILL) {
sbuf_trim(sb);
sbuf_printf(sb, " (Reason text inaccessible)");
}
sbuf_cat(sb, "\n");
sbuf_finish(sb);
log(LOG_INFO, "%s", sbuf_data(sb));
sbuf_delete(sb);
exit1(td, 0, sig);
return (0);
}
#ifdef COMPAT_43
/*
* The dirty work is handled by kern_wait().
*/
int
owait(struct thread *td, struct owait_args *uap __unused)
{
int error, status;
error = kern_wait(td, WAIT_ANY, &status, 0, NULL);
if (error == 0)
td->td_retval[1] = status;
return (error);
}
#endif /* COMPAT_43 */
/*
* The dirty work is handled by kern_wait().
*/
int
sys_wait4(struct thread *td, struct wait4_args *uap)
{
struct rusage ru, *rup;
int error, status;
if (uap->rusage != NULL)
rup = &ru;
else
rup = NULL;
error = kern_wait(td, uap->pid, &status, uap->options, rup);
if (uap->status != NULL && error == 0 && td->td_retval[0] != 0)
error = copyout(&status, uap->status, sizeof(status));
if (uap->rusage != NULL && error == 0 && td->td_retval[0] != 0)
error = copyout(&ru, uap->rusage, sizeof(struct rusage));
return (error);
}
int
sys_wait6(struct thread *td, struct wait6_args *uap)
{
struct __wrusage wru, *wrup;
siginfo_t si, *sip;
idtype_t idtype;
id_t id;
int error, status;
idtype = uap->idtype;
id = uap->id;
if (uap->wrusage != NULL)
wrup = &wru;
else
wrup = NULL;
if (uap->info != NULL) {
sip = &si;
bzero(sip, sizeof(*sip));
} else
sip = NULL;
/*
* We expect all callers of wait6() to know about WEXITED and
* WTRAPPED.
*/
error = kern_wait6(td, idtype, id, &status, uap->options, wrup, sip);
if (uap->status != NULL && error == 0 && td->td_retval[0] != 0)
error = copyout(&status, uap->status, sizeof(status));
if (uap->wrusage != NULL && error == 0 && td->td_retval[0] != 0)
error = copyout(&wru, uap->wrusage, sizeof(wru));
if (uap->info != NULL && error == 0)
error = copyout(&si, uap->info, sizeof(si));
return (error);
}
/*
* Reap the remains of a zombie process and optionally return status and
* rusage. Asserts and will release both the proctree_lock and the process
* lock as part of its work.
*/
void
proc_reap(struct thread *td, struct proc *p, int *status, int options)
{
struct proc *q, *t;
sx_assert(&proctree_lock, SA_XLOCKED);
PROC_LOCK_ASSERT(p, MA_OWNED);
PROC_SLOCK_ASSERT(p, MA_OWNED);
KASSERT(p->p_state == PRS_ZOMBIE, ("proc_reap: !PRS_ZOMBIE"));
q = td->td_proc;
PROC_SUNLOCK(p);
if (status)
*status = KW_EXITCODE(p->p_xexit, p->p_xsig);
if (options & WNOWAIT) {
/*
* Only poll, returning the status. Caller does not wish to
* release the proc struct just yet.
*/
PROC_UNLOCK(p);
sx_xunlock(&proctree_lock);
return;
}
PROC_LOCK(q);
sigqueue_take(p->p_ksi);
PROC_UNLOCK(q);
/*
* If we got the child via a ptrace 'attach', we need to give it back
* to the old parent.
*/
if (p->p_oppid != 0 && p->p_oppid != p->p_pptr->p_pid) {
PROC_UNLOCK(p);
t = proc_realparent(p);
PROC_LOCK(t);
PROC_LOCK(p);
CTR2(KTR_PTRACE,
"wait: traced child %d moved back to parent %d", p->p_pid,
t->p_pid);
proc_reparent(p, t);
p->p_oppid = 0;
PROC_UNLOCK(p);
pksignal(t, SIGCHLD, p->p_ksi);
wakeup(t);
cv_broadcast(&p->p_pwait);
PROC_UNLOCK(t);
sx_xunlock(&proctree_lock);
return;
}
p->p_oppid = 0;
PROC_UNLOCK(p);
/*
* Remove other references to this process to ensure we have an
* exclusive reference.
*/
sx_xlock(&allproc_lock);
LIST_REMOVE(p, p_list); /* off zombproc */
sx_xunlock(&allproc_lock);
LIST_REMOVE(p, p_sibling);
reaper_abandon_children(p, true);
LIST_REMOVE(p, p_reapsibling);
PROC_LOCK(p);
clear_orphan(p);
PROC_UNLOCK(p);
leavepgrp(p);
if (p->p_procdesc != NULL)
procdesc_reap(p);
sx_xunlock(&proctree_lock);
PROC_LOCK(p);
knlist_detach(p->p_klist);
p->p_klist = NULL;
PROC_UNLOCK(p);
/*
* Removal from allproc list and process group list paired with
* PROC_LOCK which was executed during that time should guarantee
* nothing can reach this process anymore. As such further locking
* is unnecessary.
*/
p->p_xexit = p->p_xsig = 0; /* XXX: why? */
PROC_LOCK(q);
ruadd(&q->p_stats->p_cru, &q->p_crux, &p->p_ru, &p->p_rux);
PROC_UNLOCK(q);
/*
* Decrement the count of procs running with this uid.
*/
(void)chgproccnt(p->p_ucred->cr_ruidinfo, -1, 0);
/*
* Destroy resource accounting information associated with the process.
*/
#ifdef RACCT
if (racct_enable) {
PROC_LOCK(p);
racct_sub(p, RACCT_NPROC, 1);
PROC_UNLOCK(p);
}
#endif
racct_proc_exit(p);
/*
* Free credentials, arguments, and sigacts.
*/
crfree(p->p_ucred);
proc_set_cred(p, NULL);
pargs_drop(p->p_args);
p->p_args = NULL;
sigacts_free(p->p_sigacts);
p->p_sigacts = NULL;
/*
* Do any thread-system specific cleanups.
*/
thread_wait(p);
/*
* Give vm and machine-dependent layer a chance to free anything that
* cpu_exit couldn't release while still running in process context.
*/
vm_waitproc(p);
#ifdef MAC
mac_proc_destroy(p);
#endif
/*
* Free any domain policy that's still hiding around.
*/
vm_domain_policy_cleanup(&p->p_vm_dom_policy);
KASSERT(FIRST_THREAD_IN_PROC(p),
("proc_reap: no residual thread!"));
uma_zfree(proc_zone, p);
atomic_add_int(&nprocs, -1);
}
static int
proc_to_reap(struct thread *td, struct proc *p, idtype_t idtype, id_t id,
int *status, int options, struct __wrusage *wrusage, siginfo_t *siginfo,
int check_only)
{
struct rusage *rup;
sx_assert(&proctree_lock, SA_XLOCKED);
PROC_LOCK(p);
switch (idtype) {
case P_ALL:
if (p->p_procdesc != NULL) {
PROC_UNLOCK(p);
return (0);
}
break;
case P_PID:
if (p->p_pid != (pid_t)id) {
PROC_UNLOCK(p);
return (0);
}
break;
case P_PGID:
if (p->p_pgid != (pid_t)id) {
PROC_UNLOCK(p);
return (0);
}
break;
case P_SID:
if (p->p_session->s_sid != (pid_t)id) {
PROC_UNLOCK(p);
return (0);
}
break;
case P_UID:
if (p->p_ucred->cr_uid != (uid_t)id) {
PROC_UNLOCK(p);
return (0);
}
break;
case P_GID:
if (p->p_ucred->cr_gid != (gid_t)id) {
PROC_UNLOCK(p);
return (0);
}
break;
case P_JAILID:
if (p->p_ucred->cr_prison->pr_id != (int)id) {
PROC_UNLOCK(p);
return (0);
}
break;
/*
* It seems that the thread structures get zeroed out
* at process exit. This makes it impossible to
* support P_SETID, P_CID or P_CPUID.
*/
default:
PROC_UNLOCK(p);
return (0);
}
if (p_canwait(td, p)) {
PROC_UNLOCK(p);
return (0);
}
if (((options & WEXITED) == 0) && (p->p_state == PRS_ZOMBIE)) {
PROC_UNLOCK(p);
return (0);
}
/*
* This special case handles a kthread spawned by linux_clone
* (see linux_misc.c). The linux_wait4 and linux_waitpid
* functions need to be able to distinguish between waiting
* on a process and waiting on a thread. It is a thread if
* p_sigparent is not SIGCHLD, and the WLINUXCLONE option
* signifies we want to wait for threads and not processes.
*/
if ((p->p_sigparent != SIGCHLD) ^
((options & WLINUXCLONE) != 0)) {
PROC_UNLOCK(p);
return (0);
}
if (siginfo != NULL) {
bzero(siginfo, sizeof(*siginfo));
siginfo->si_errno = 0;
/*
* SUSv4 requires that the si_signo value is always
* SIGCHLD. Obey it despite the rfork(2) interface
* allows to request other signal for child exit
* notification.
*/
siginfo->si_signo = SIGCHLD;
/*
* This is still a rough estimate. We will fix the
* cases TRAPPED, STOPPED, and CONTINUED later.
*/
if (WCOREDUMP(p->p_xsig)) {
siginfo->si_code = CLD_DUMPED;
siginfo->si_status = WTERMSIG(p->p_xsig);
} else if (WIFSIGNALED(p->p_xsig)) {
siginfo->si_code = CLD_KILLED;
siginfo->si_status = WTERMSIG(p->p_xsig);
} else {
siginfo->si_code = CLD_EXITED;
siginfo->si_status = p->p_xexit;
}
siginfo->si_pid = p->p_pid;
siginfo->si_uid = p->p_ucred->cr_uid;
/*
* The si_addr field would be useful additional
* detail, but apparently the PC value may be lost
* when we reach this point. bzero() above sets
* siginfo->si_addr to NULL.
*/
}
/*
* There should be no reason to limit resources usage info to
* exited processes only. A snapshot about any resources used
* by a stopped process may be exactly what is needed.
*/
if (wrusage != NULL) {
rup = &wrusage->wru_self;
*rup = p->p_ru;
PROC_STATLOCK(p);
calcru(p, &rup->ru_utime, &rup->ru_stime);
PROC_STATUNLOCK(p);
rup = &wrusage->wru_children;
*rup = p->p_stats->p_cru;
calccru(p, &rup->ru_utime, &rup->ru_stime);
}
if (p->p_state == PRS_ZOMBIE && !check_only) {
PROC_SLOCK(p);
proc_reap(td, p, status, options);
return (-1);
}
return (1);
}
int
kern_wait(struct thread *td, pid_t pid, int *status, int options,
struct rusage *rusage)
{
struct __wrusage wru, *wrup;
idtype_t idtype;
id_t id;
int ret;
/*
* Translate the special pid values into the (idtype, pid)
* pair for kern_wait6. The WAIT_MYPGRP case is handled by
* kern_wait6() on its own.
*/
if (pid == WAIT_ANY) {
idtype = P_ALL;
id = 0;
} else if (pid < 0) {
idtype = P_PGID;
id = (id_t)-pid;
} else {
idtype = P_PID;
id = (id_t)pid;
}
if (rusage != NULL)
wrup = &wru;
else
wrup = NULL;
/*
* For backward compatibility we implicitly add flags WEXITED
* and WTRAPPED here.
*/
options |= WEXITED | WTRAPPED;
ret = kern_wait6(td, idtype, id, status, options, wrup, NULL);
if (rusage != NULL)
*rusage = wru.wru_self;
return (ret);
}
static void
report_alive_proc(struct thread *td, struct proc *p, siginfo_t *siginfo,
int *status, int options, int si_code)
{
bool cont;
PROC_LOCK_ASSERT(p, MA_OWNED);
sx_assert(&proctree_lock, SA_XLOCKED);
MPASS(si_code == CLD_TRAPPED || si_code == CLD_STOPPED ||
si_code == CLD_CONTINUED);
cont = si_code == CLD_CONTINUED;
if ((options & WNOWAIT) == 0) {
if (cont)
p->p_flag &= ~P_CONTINUED;
else
p->p_flag |= P_WAITED;
PROC_LOCK(td->td_proc);
sigqueue_take(p->p_ksi);
PROC_UNLOCK(td->td_proc);
}
sx_xunlock(&proctree_lock);
if (siginfo != NULL) {
siginfo->si_code = si_code;
siginfo->si_status = cont ? SIGCONT : p->p_xsig;
}
if (status != NULL)
*status = cont ? SIGCONT : W_STOPCODE(p->p_xsig);
PROC_UNLOCK(p);
td->td_retval[0] = p->p_pid;
}
int
kern_wait6(struct thread *td, idtype_t idtype, id_t id, int *status,
int options, struct __wrusage *wrusage, siginfo_t *siginfo)
{
struct proc *p, *q;
pid_t pid;
int error, nfound, ret;
AUDIT_ARG_VALUE((int)idtype); /* XXX - This is likely wrong! */
AUDIT_ARG_PID((pid_t)id); /* XXX - This may be wrong! */
AUDIT_ARG_VALUE(options);
q = td->td_proc;
if ((pid_t)id == WAIT_MYPGRP && (idtype == P_PID || idtype == P_PGID)) {
PROC_LOCK(q);
id = (id_t)q->p_pgid;
PROC_UNLOCK(q);
idtype = P_PGID;
}
/* If we don't know the option, just return. */
if ((options & ~(WUNTRACED | WNOHANG | WCONTINUED | WNOWAIT |
WEXITED | WTRAPPED | WLINUXCLONE)) != 0)
return (EINVAL);
if ((options & (WEXITED | WUNTRACED | WCONTINUED | WTRAPPED)) == 0) {
/*
* We will be unable to find any matching processes,
* because there are no known events to look for.
* Prefer to return error instead of blocking
* indefinitely.
*/
return (EINVAL);
}
loop:
if (q->p_flag & P_STATCHILD) {
PROC_LOCK(q);
q->p_flag &= ~P_STATCHILD;
PROC_UNLOCK(q);
}
nfound = 0;
sx_xlock(&proctree_lock);
LIST_FOREACH(p, &q->p_children, p_sibling) {
pid = p->p_pid;
ret = proc_to_reap(td, p, idtype, id, status, options,
wrusage, siginfo, 0);
if (ret == 0)
continue;
else if (ret == 1)
nfound++;
else {
td->td_retval[0] = pid;
return (0);
}
PROC_LOCK_ASSERT(p, MA_OWNED);
if ((options & (WTRAPPED | WUNTRACED)) != 0)
PROC_SLOCK(p);
if ((options & WTRAPPED) != 0 &&
(p->p_flag & P_TRACED) != 0 &&
(p->p_flag & (P_STOPPED_TRACE | P_STOPPED_SIG)) != 0 &&
p->p_suspcount == p->p_numthreads &&
(p->p_flag & P_WAITED) == 0) {
PROC_SUNLOCK(p);
CTR4(KTR_PTRACE,
"wait: returning trapped pid %d status %#x "
"(xstat %d) xthread %d",
p->p_pid, W_STOPCODE(p->p_xsig), p->p_xsig,
p->p_xthread != NULL ?
p->p_xthread->td_tid : -1);
report_alive_proc(td, p, siginfo, status, options,
CLD_TRAPPED);
return (0);
}
if ((options & WUNTRACED) != 0 &&
(p->p_flag & P_STOPPED_SIG) != 0 &&
p->p_suspcount == p->p_numthreads &&
(p->p_flag & P_WAITED) == 0) {
PROC_SUNLOCK(p);
report_alive_proc(td, p, siginfo, status, options,
CLD_STOPPED);
return (0);
}
if ((options & (WTRAPPED | WUNTRACED)) != 0)
PROC_SUNLOCK(p);
if ((options & WCONTINUED) != 0 &&
(p->p_flag & P_CONTINUED) != 0) {
report_alive_proc(td, p, siginfo, status, options,
CLD_CONTINUED);
return (0);
}
PROC_UNLOCK(p);
}
/*
* Look in the orphans list too, to allow the parent to
* collect it's child exit status even if child is being
* debugged.
*
* Debugger detaches from the parent upon successful
* switch-over from parent to child. At this point due to
* re-parenting the parent loses the child to debugger and a
* wait4(2) call would report that it has no children to wait
* for. By maintaining a list of orphans we allow the parent
* to successfully wait until the child becomes a zombie.
*/
if (nfound == 0) {
LIST_FOREACH(p, &q->p_orphans, p_orphan) {
ret = proc_to_reap(td, p, idtype, id, NULL, options,
NULL, NULL, 1);
if (ret != 0) {
KASSERT(ret != -1, ("reaped an orphan (pid %d)",
(int)td->td_retval[0]));
PROC_UNLOCK(p);
nfound++;
break;
}
}
}
if (nfound == 0) {
sx_xunlock(&proctree_lock);
return (ECHILD);
}
if (options & WNOHANG) {
sx_xunlock(&proctree_lock);
td->td_retval[0] = 0;
return (0);
}
PROC_LOCK(q);
sx_xunlock(&proctree_lock);
if (q->p_flag & P_STATCHILD) {
q->p_flag &= ~P_STATCHILD;
error = 0;
} else
error = msleep(q, &q->p_mtx, PWAIT | PCATCH, "wait", 0);
PROC_UNLOCK(q);
if (error)
return (error);
goto loop;
}
/*
* Make process 'parent' the new parent of process 'child'.
* Must be called with an exclusive hold of proctree lock.
*/
void
proc_reparent(struct proc *child, struct proc *parent)
{
sx_assert(&proctree_lock, SX_XLOCKED);
PROC_LOCK_ASSERT(child, MA_OWNED);
if (child->p_pptr == parent)
return;
PROC_LOCK(child->p_pptr);
sigqueue_take(child->p_ksi);
PROC_UNLOCK(child->p_pptr);
LIST_REMOVE(child, p_sibling);
LIST_INSERT_HEAD(&parent->p_children, child, p_sibling);
clear_orphan(child);
if (child->p_flag & P_TRACED) {
if (LIST_EMPTY(&child->p_pptr->p_orphans)) {
child->p_treeflag |= P_TREE_FIRST_ORPHAN;
LIST_INSERT_HEAD(&child->p_pptr->p_orphans, child,
p_orphan);
} else {
LIST_INSERT_AFTER(LIST_FIRST(&child->p_pptr->p_orphans),
child, p_orphan);
}
child->p_treeflag |= P_TREE_ORPHANED;
}
child->p_pptr = parent;
}