freebsd-dev/sys/kern/kern_exit.c
Mateusz Guzik e3d3e8289b Revert "fork: fix use-after-free with vfork"
This unreliably breaks libc handling of vfork where forking succeded,
but execve did not.

vfork code in libc performs waitpid with WNOHANG in case of failed exec.
With the fix exit codepath was waking up the parent before the child
fully transitioned to a zombie. Woken up parent would waitpid, which
could find a not-yet-zombie child and fail to reap it due to the WNOHANG
flag.

While removing the flag fixes the problem, it is not an option due to older
releases which would still suffer from the kernel change.

Revert the fix until a solution can be worked out.

Note that while use-after-free which gets back due to the revert is a real
bug, it's side-effects are limited due to the fact that struct proc memory
is never released by UMA.
2018-11-23 04:38:50 +00:00

1361 lines
34 KiB
C

/*-
* SPDX-License-Identifier: BSD-3-Clause
*
* 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_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>
#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);
EVENTHANDLER_LIST_DECLARE(process_exit);
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)
return (child->p_pptr->p_pid == child->p_oppid ?
child->p_pptr : initproc);
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, true);
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;
ksiginfo_t *ksi, *ksi1;
int signal_parent;
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_DIRECT_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);
/*
* 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);
sx_xlock(&proctree_lock);
/*
* Move proc from allproc queue to zombproc.
*/
sx_xlock(&allproc_lock);
LIST_REMOVE(p, p_list);
LIST_INSERT_HEAD(&zombproc, p, p_list);
sx_xunlock(&allproc_lock);
/*
* Reparent all children processes:
* - traced ones to the original parent (or init if we are that parent)
* - the rest to init
*/
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);
ksi = ksiginfo_alloc(TRUE);
PROC_LOCK(q);
q->p_sigparent = SIGCHLD;
if (!(q->p_flag & P_TRACED)) {
proc_reparent(q, q->p_reaper, true);
if (q->p_state == PRS_ZOMBIE) {
/*
* Inform reaper about the reparented
* zombie, since wait(2) has something
* new to report. Guarantee queueing
* of the SIGCHLD signal, similar to
* the _exit() behaviour, by providing
* our ksiginfo. Ksi is freed by the
* signal delivery.
*/
if (q->p_ksi == NULL) {
ksi1 = NULL;
} else {
ksiginfo_copy(q->p_ksi, ksi);
ksi->ksi_flags |= KSI_INS;
ksi1 = ksi;
ksi = NULL;
}
PROC_LOCK(q->p_reaper);
pksignal(q->p_reaper, SIGCHLD, ksi1);
PROC_UNLOCK(q->p_reaper);
} else if (q->p_pdeathsig > 0) {
/*
* The child asked to received a signal
* when we exit.
*/
kern_psignal(q, q->p_pdeathsig);
}
} 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, true);
} else {
PROC_LOCK(t);
proc_reparent(q, t, true);
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);
if (ksi != NULL)
ksiginfo_free(ksi);
}
/*
* Also get rid of our orphans.
*/
while ((q = LIST_FIRST(&p->p_orphans)) != NULL) {
PROC_LOCK(q);
/*
* If we are the real parent of this process
* but it has been reparented to a debugger, then
* check if it asked for a signal when we exit.
*/
if (q->p_pdeathsig > 0)
kern_psignal(q, q->p_pdeathsig);
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;
#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().
*/
signal_parent = 0;
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, true);
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) {
signal_parent = 1;
} else if (p->p_sigparent != 0) {
if (p->p_sigparent == SIGCHLD) {
signal_parent = 1;
} else { /* LINUX thread */
signal_parent = 2;
}
}
} else
PROC_LOCK(p->p_pptr);
sx_xunlock(&proctree_lock);
if (signal_parent == 1) {
childproc_exited(p);
} else if (signal_parent == 2) {
kern_psignal(p->p_pptr, p->p_sigparent);
}
/* Tell the prison that we are gone. */
prison_proc_free(p->p_ucred->cr_prison);
/*
* 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);
KASSERT(p->p_state == PRS_ZOMBIE, ("proc_reap: !PRS_ZOMBIE"));
mtx_spin_wait_unlocked(&p->p_slock);
q = td->td_proc;
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 != 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, false);
PROC_UNLOCK(p);
pksignal(t, SIGCHLD, p->p_ksi);
wakeup(t);
cv_broadcast(&p->p_pwait);
PROC_UNLOCK(t);
sx_xunlock(&proctree_lock);
return;
}
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);
sx_xlock(PIDHASHLOCK(p->p_pid));
LIST_REMOVE(p, p_hash);
sx_xunlock(PIDHASHLOCK(p->p_pid));
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
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_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;
bool report;
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);
}
sx_xlock(&proctree_lock);
loop_locked:
nfound = 0;
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) {
td->td_retval[0] = pid;
return (0);
}
nfound++;
PROC_LOCK_ASSERT(p, MA_OWNED);
if ((options & WTRAPPED) != 0 &&
(p->p_flag & P_TRACED) != 0) {
PROC_SLOCK(p);
report =
((p->p_flag & (P_STOPPED_TRACE | P_STOPPED_SIG)) &&
p->p_suspcount == p->p_numthreads &&
(p->p_flag & P_WAITED) == 0);
PROC_SUNLOCK(p);
if (report) {
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) {
PROC_SLOCK(p);
report = (p->p_suspcount == p->p_numthreads &&
((p->p_flag & P_WAITED) == 0));
PROC_SUNLOCK(p);
if (report) {
report_alive_proc(td, p, siginfo, status,
options, CLD_STOPPED);
return (0);
}
}
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);
if (q->p_flag & P_STATCHILD) {
q->p_flag &= ~P_STATCHILD;
PROC_UNLOCK(q);
goto loop_locked;
}
sx_xunlock(&proctree_lock);
error = msleep(q, &q->p_mtx, PWAIT | PCATCH | PDROP, "wait", 0);
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, bool set_oppid)
{
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;
if (set_oppid)
child->p_oppid = parent->p_pid;
}