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0c8b378fe3
freebsd-dev/sys/kern/kern_exit.c
rwatson 0283388af8 o Merge contents of struct pcred into struct ucred. Specifically, add the 
real uid, saved uid, real gid, and saved gid to ucred, as well as the
  pcred->pc_uidinfo, which was associated with the real uid, only rename
  it to cr_ruidinfo so as not to conflict with cr_uidinfo, which
  corresponds to the effective uid.
o Remove p_cred from struct proc; add p_ucred to struct proc, replacing
  original macro that pointed.
  p->p_ucred to p->p_cred->pc_ucred.
o Universally update code so that it makes use of ucred instead of pcred,
  p->p_ucred instead of p->p_pcred, cr_ruidinfo instead of p_uidinfo,
  cr_{r,sv}{u,g}id instead of p_*, etc.
o Remove pcred0 and its initialization from init_main.c; initialize
  cr_ruidinfo there.
o Restruction many credential modification chunks to always crdup while
  we figure out locking and optimizations; generally speaking, this
  means moving to a structure like this:
        newcred = crdup(oldcred);
        ...
        p->p_ucred = newcred;
        crfree(oldcred);
  It's not race-free, but better than nothing.  There are also races
  in sys_process.c, all inter-process authorization, fork, exec, and
  exit.
o Remove sigio->sio_ruid since sigio->sio_ucred now contains the ruid;
  remove comments indicating that the old arrangement was a problem.
o Restructure exec1() a little to use newcred/oldcred arrangement, and
  use improved uid management primitives.
o Clean up exit1() so as to do less work in credential cleanup due to
  pcred removal.
o Clean up fork1() so as to do less work in credential cleanup and
  allocation.
o Clean up ktrcanset() to take into account changes, and move to using
  suser_xxx() instead of performing a direct uid==0 comparision.
o Improve commenting in various kern_prot.c credential modification
  calls to better document current behavior.  In a couple of places,
  current behavior is a little questionable and we need to check
  POSIX.1 to make sure it's "right".  More commenting work still
  remains to be done.
o Update credential management calls, such as crfree(), to take into
  account new ruidinfo reference.
o Modify or add the following uid and gid helper routines:
      change_euid()
      change_egid()
      change_ruid()
      change_rgid()
      change_svuid()
      change_svgid()
  In each case, the call now acts on a credential not a process, and as
  such no longer requires more complicated process locking/etc.  They
  now assume the caller will do any necessary allocation of an
  exclusive credential reference.  Each is commented to document its
  reference requirements.
o CANSIGIO() is simplified to require only credentials, not processes
  and pcreds.
o Remove lots of (p_pcred==NULL) checks.
o Add an XXX to authorization code in nfs_lock.c, since it's
  questionable, and needs to be considered carefully.
o Simplify posix4 authorization code to require only credentials, not
  processes and pcreds.  Note that this authorization, as well as
  CANSIGIO(), needs to be updated to use the p_cansignal() and
  p_cansched() centralized authorization routines, as they currently
  do not take into account some desirable restrictions that are handled
  by the centralized routines, as well as being inconsistent with other
  similar authorization instances.
o Update libkvm to take these changes into account.

Obtained from:	TrustedBSD Project
Reviewed by:	green, bde, jhb, freebsd-arch, freebsd-audit
2001-05-25 16:59:11 +00:00

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/*
* Copyright (c) 1982, 1986, 1989, 1991, 1993
* The Regents of the University of California. All rights reserved.
* (c) UNIX System Laboratories, Inc.
* All or some portions of this file are derived from material licensed
* to the University of California by American Telephone and Telegraph
* Co. or Unix System Laboratories, Inc. and are reproduced herein with
* the permission of UNIX System Laboratories, Inc.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* @(#)kern_exit.c 8.7 (Berkeley) 2/12/94
* $FreeBSD$
*/
#include "opt_compat.h"
#include "opt_ktrace.h"
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/sysproto.h>
#include <sys/kernel.h>
#include <sys/malloc.h>
#include <sys/lock.h>
#include <sys/mutex.h>
#include <sys/proc.h>
#include <sys/pioctl.h>
#include <sys/tty.h>
#include <sys/wait.h>
#include <sys/vnode.h>
#include <sys/resourcevar.h>
#include <sys/signalvar.h>
#include <sys/sx.h>
#include <sys/ptrace.h>
#include <sys/acct.h> /* for acct_process() function prototype */
#include <sys/filedesc.h>
#include <sys/shm.h>
#include <sys/sem.h>
#include <sys/aio.h>
#include <sys/jail.h>
#include <vm/vm.h>
#include <vm/vm_param.h>
#include <vm/pmap.h>
#include <vm/vm_map.h>
#include <vm/vm_zone.h>
#include <sys/user.h>
/* Required to be non-static for SysVR4 emulator */
MALLOC_DEFINE(M_ZOMBIE, "zombie", "zombie proc status");
static MALLOC_DEFINE(M_ATEXIT, "atexit", "atexit callback");
static int wait1 __P((struct proc *, struct wait_args *, int));
/*
* callout list for things to do at exit time
*/
struct exitlist {
exitlist_fn function;
TAILQ_ENTRY(exitlist) next;
};
TAILQ_HEAD(exit_list_head, exitlist);
static struct exit_list_head exit_list = TAILQ_HEAD_INITIALIZER(exit_list);
/*
* exit --
* Death of process.
*/
void
sys_exit(p, uap)
struct proc *p;
struct sys_exit_args /* {
int rval;
} */ *uap;
{
exit1(p, W_EXITCODE(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(p, rv)
register struct proc *p;
int rv;
{
register struct proc *q, *nq;
register struct vmspace *vm;
struct exitlist *ep;
if (p->p_pid == 1) {
printf("init died (signal %d, exit %d)\n",
WTERMSIG(rv), WEXITSTATUS(rv));
panic("Going nowhere without my init!");
}
aio_proc_rundown(p);
/* are we a task leader? */
PROC_LOCK(p);
if(p == p->p_leader) {
struct kill_args killArgs;
killArgs.signum = SIGKILL;
q = p->p_peers;
while(q) {
killArgs.pid = q->p_pid;
/*
* The interface for kill is better
* than the internal signal
*/
PROC_UNLOCK(p);
kill(p, &killArgs);
PROC_LOCK(p);
nq = q;
q = q->p_peers;
}
while (p->p_peers)
msleep((caddr_t)p, &p->p_mtx, PWAIT, "exit1", 0);
}
PROC_UNLOCK(p);
#ifdef PGINPROF
vmsizmon();
#endif
STOPEVENT(p, S_EXIT, rv);
wakeup(&p->p_stype); /* Wakeup anyone in procfs' PIOCWAIT */
/*
* Check if any loadable modules need anything done at process exit.
* e.g. SYSV IPC stuff
* XXX what if one of these generates an error?
*/
TAILQ_FOREACH(ep, &exit_list, next)
(*ep->function)(p);
stopprofclock(p);
MALLOC(p->p_ru, struct rusage *, sizeof(struct rusage),
M_ZOMBIE, M_WAITOK);
/*
* If parent is waiting for us to exit or exec,
* P_PPWAIT is set; we will wakeup the parent below.
*/
PROC_LOCK(p);
p->p_flag &= ~(P_TRACED | P_PPWAIT);
p->p_flag |= P_WEXIT;
SIGEMPTYSET(p->p_siglist);
PROC_UNLOCK(p);
if (timevalisset(&p->p_realtimer.it_value))
callout_stop(&p->p_itcallout);
/*
* Reset any sigio structures pointing to us as a result of
* F_SETOWN with our pid.
*/
funsetownlst(&p->p_sigiolst);
/*
* Close open files and release open-file table.
* This may block!
*/
fdfree(p);
/*
* Remove ourself from our leader's peer list and wake our leader.
*/
PROC_LOCK(p);
if(p->p_leader->p_peers) {
q = p->p_leader;
while(q->p_peers != p)
q = q->p_peers;
q->p_peers = p->p_peers;
wakeup((caddr_t)p->p_leader);
}
PROC_UNLOCK(p);
/*
* XXX Shutdown SYSV semaphores
*/
semexit(p);
/* The next two chunks should probably be moved to vmspace_exit. */
vm = p->p_vmspace;
/*
* Release user portion of address space.
* This releases references to vnodes,
* which could cause I/O if the file has been unlinked.
* Need to do this early enough that we can still sleep.
* Can't free the entire vmspace as the kernel stack
* may be mapped within that space also.
*/
mtx_lock(&vm_mtx);
if (vm->vm_refcnt == 1) {
if (vm->vm_shm)
shmexit(p);
pmap_remove_pages(vmspace_pmap(vm), VM_MIN_ADDRESS,
VM_MAXUSER_ADDRESS);
(void) vm_map_remove(&vm->vm_map, VM_MIN_ADDRESS,
VM_MAXUSER_ADDRESS);
}
mtx_unlock(&vm_mtx);
PROC_LOCK(p);
if (SESS_LEADER(p)) {
register struct session *sp = p->p_session;
PROC_UNLOCK(p);
if (sp->s_ttyvp) {
/*
* Controlling process.
* Signal foreground pgrp,
* drain controlling terminal
* and revoke access to controlling terminal.
*/
if (sp->s_ttyp && (sp->s_ttyp->t_session == sp)) {
if (sp->s_ttyp->t_pgrp)
pgsignal(sp->s_ttyp->t_pgrp, SIGHUP, 1);
(void) ttywait(sp->s_ttyp);
/*
* The tty could have been revoked
* if we blocked.
*/
if (sp->s_ttyvp)
VOP_REVOKE(sp->s_ttyvp, REVOKEALL);
}
if (sp->s_ttyvp)
vrele(sp->s_ttyvp);
sp->s_ttyvp = NULL;
/*
* s_ttyp is not zero'd; we use this to indicate
* that the session once had a controlling terminal.
* (for logging and informational purposes)
*/
}
sp->s_leader = NULL;
} else
PROC_UNLOCK(p);
fixjobc(p, p->p_pgrp, 0);
(void)acct_process(p);
#ifdef KTRACE
/*
* release trace file
*/
p->p_traceflag = 0; /* don't trace the vrele() */
if (p->p_tracep)
vrele(p->p_tracep);
#endif
/*
* 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);
sx_xlock(&proctree_lock);
q = LIST_FIRST(&p->p_children);
if (q != NULL) /* only need this if any child is S_ZOMB */
wakeup((caddr_t) initproc);
for (; q != NULL; q = nq) {
nq = LIST_NEXT(q, p_sibling);
PROC_LOCK(q);
proc_reparent(q, initproc);
q->p_sigparent = SIGCHLD;
/*
* Traced processes are killed
* since their existence means someone is screwing up.
*/
if (q->p_flag & P_TRACED) {
q->p_flag &= ~P_TRACED;
psignal(q, SIGKILL);
}
PROC_UNLOCK(q);
}
/*
* Save exit status and final rusage info, adding in child rusage
* info and self times.
*/
p->p_xstat = rv;
*p->p_ru = p->p_stats->p_ru;
mtx_lock_spin(&sched_lock);
calcru(p, &p->p_ru->ru_utime, &p->p_ru->ru_stime, NULL);
mtx_unlock_spin(&sched_lock);
ruadd(p->p_ru, &p->p_stats->p_cru);
/*
* Pretend that an mi_switch() to the next process occurs now. We
* must set `switchtime' directly since we will call cpu_switch()
* directly. Set it now so that the rest of the exit time gets
* counted somewhere if possible.
*/
mtx_lock_spin(&sched_lock);
microuptime(PCPU_PTR(switchtime));
PCPU_SET(switchticks, ticks);
mtx_unlock_spin(&sched_lock);
/*
* notify interested parties of our demise.
*/
PROC_LOCK(p);
KNOTE(&p->p_klist, NOTE_EXIT);
/*
* Notify parent that we're gone. If parent has the PS_NOCLDWAIT
* flag set, notify process 1 instead (and hope it will handle
* this situation).
*/
if (p->p_pptr->p_procsig->ps_flag & PS_NOCLDWAIT) {
struct proc *pp = p->p_pptr;
proc_reparent(p, initproc);
/*
* If this was the last child of our parent, notify
* parent, so in case he was wait(2)ing, he will
* continue.
*/
if (LIST_EMPTY(&pp->p_children))
wakeup((caddr_t)pp);
}
PROC_LOCK(p->p_pptr);
if (p->p_sigparent && p->p_pptr != initproc)
psignal(p->p_pptr, p->p_sigparent);
else
psignal(p->p_pptr, SIGCHLD);
PROC_UNLOCK(p->p_pptr);
PROC_UNLOCK(p);
sx_xunlock(&proctree_lock);
/*
* Clear curproc after we've done all operations
* that could block, and before tearing down the rest
* of the process state that might be used from clock, etc.
* Also, can't clear curproc while we're still runnable,
* as we're not on a run queue (we are current, just not
* a proper proc any longer!).
*
* Other substructures are freed from wait().
*/
mtx_assert(&Giant, MA_OWNED);
if (--p->p_limit->p_refcnt == 0) {
FREE(p->p_limit, M_SUBPROC);
p->p_limit = NULL;
}
/*
* Finally, call machine-dependent code to release the remaining
* resources including address space, the kernel stack and pcb.
* The address space is released by "vmspace_free(p->p_vmspace)";
* This is machine-dependent, as we may have to change stacks
* or ensure that the current one isn't reallocated before we
* finish. cpu_exit will end with a call to cpu_switch(), finishing
* our execution (pun intended).
*/
cpu_exit(p);
}
#ifdef COMPAT_43
int
owait(p, uap)
struct proc *p;
register struct owait_args /* {
int dummy;
} */ *uap;
{
struct wait_args w;
w.options = 0;
w.rusage = NULL;
w.pid = WAIT_ANY;
w.status = NULL;
return (wait1(p, &w, 1));
}
#endif /* COMPAT_43 */
int
wait4(p, uap)
struct proc *p;
struct wait_args *uap;
{
return (wait1(p, uap, 0));
}
static int
wait1(q, uap, compat)
register struct proc *q;
register struct wait_args /* {
int pid;
int *status;
int options;
struct rusage *rusage;
} */ *uap;
int compat;
{
register int nfound;
register struct proc *p, *t;
int status, error;
if (uap->pid == 0)
uap->pid = -q->p_pgid;
if (uap->options &~ (WUNTRACED|WNOHANG|WLINUXCLONE))
return (EINVAL);
loop:
nfound = 0;
sx_slock(&proctree_lock);
LIST_FOREACH(p, &q->p_children, p_sibling) {
if (uap->pid != WAIT_ANY &&
p->p_pid != uap->pid && p->p_pgid != -uap->pid)
continue;
/*
* 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.
*/
PROC_LOCK(p);
if ((p->p_sigparent != SIGCHLD) ^
((uap->options & WLINUXCLONE) != 0)) {
PROC_UNLOCK(p);
continue;
}
nfound++;
mtx_lock_spin(&sched_lock);
if (p->p_stat == SZOMB) {
/* charge childs scheduling cpu usage to parent */
if (curproc->p_pid != 1) {
curproc->p_estcpu =
ESTCPULIM(curproc->p_estcpu + p->p_estcpu);
}
mtx_unlock_spin(&sched_lock);
PROC_UNLOCK(p);
sx_sunlock(&proctree_lock);
q->p_retval[0] = p->p_pid;
#ifdef COMPAT_43
if (compat)
q->p_retval[1] = p->p_xstat;
else
#endif
if (uap->status) {
status = p->p_xstat; /* convert to int */
if ((error = copyout((caddr_t)&status,
(caddr_t)uap->status, sizeof(status))))
return (error);
}
if (uap->rusage && (error = copyout((caddr_t)p->p_ru,
(caddr_t)uap->rusage, sizeof (struct rusage))))
return (error);
/*
* If we got the child via a ptrace 'attach',
* we need to give it back to the old parent.
*/
sx_xlock(&proctree_lock);
if (p->p_oppid) {
if ((t = pfind(p->p_oppid)) != NULL) {
PROC_LOCK(p);
p->p_oppid = 0;
proc_reparent(p, t);
PROC_UNLOCK(p);
psignal(t, SIGCHLD);
wakeup((caddr_t)t);
PROC_UNLOCK(t);
sx_xunlock(&proctree_lock);
return (0);
}
}
sx_xunlock(&proctree_lock);
PROC_LOCK(p);
p->p_xstat = 0;
PROC_UNLOCK(p);
ruadd(&q->p_stats->p_cru, p->p_ru);
FREE(p->p_ru, M_ZOMBIE);
p->p_ru = NULL;
/*
* Decrement the count of procs running with this uid.
*/
(void)chgproccnt(p->p_ucred->cr_ruidinfo, -1, 0);
/*
* Release reference to text vnode
*/
if (p->p_textvp)
vrele(p->p_textvp);
/*
* Finally finished with old proc entry.
* Unlink it from its process group and free it.
*/
leavepgrp(p);
sx_xlock(&allproc_lock);
LIST_REMOVE(p, p_list); /* off zombproc */
sx_xunlock(&allproc_lock);
sx_xlock(&proctree_lock);
LIST_REMOVE(p, p_sibling);
sx_xunlock(&proctree_lock);
/*
* Free up credentials.
*/
crfree(p->p_ucred);
p->p_ucred = NULL;
/*
* Remove unused arguments
*/
if (p->p_args && --p->p_args->ar_ref == 0)
FREE(p->p_args, M_PARGS);
if (--p->p_procsig->ps_refcnt == 0) {
if (p->p_sigacts != &p->p_addr->u_sigacts)
FREE(p->p_sigacts, M_SUBPROC);
FREE(p->p_procsig, M_SUBPROC);
p->p_procsig = NULL;
}
/*
* Give machine-dependent layer a chance
* to free anything that cpu_exit couldn't
* release while still running in process context.
*/
cpu_wait(p);
mtx_destroy(&p->p_mtx);
zfree(proc_zone, p);
nprocs--;
return (0);
}
if (p->p_stat == SSTOP && (p->p_flag & P_WAITED) == 0 &&
(p->p_flag & P_TRACED || uap->options & WUNTRACED)) {
mtx_unlock_spin(&sched_lock);
p->p_flag |= P_WAITED;
PROC_UNLOCK(p);
sx_sunlock(&proctree_lock);
q->p_retval[0] = p->p_pid;
#ifdef COMPAT_43
if (compat) {
q->p_retval[1] = W_STOPCODE(p->p_xstat);
error = 0;
} else
#endif
if (uap->status) {
status = W_STOPCODE(p->p_xstat);
error = copyout((caddr_t)&status,
(caddr_t)uap->status, sizeof(status));
} else
error = 0;
return (error);
}
mtx_unlock_spin(&sched_lock);
PROC_UNLOCK(p);
}
sx_sunlock(&proctree_lock);
if (nfound == 0)
return (ECHILD);
if (uap->options & WNOHANG) {
q->p_retval[0] = 0;
return (0);
}
if ((error = tsleep((caddr_t)q, PWAIT | PCATCH, "wait", 0)))
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(child, parent)
register struct proc *child;
register struct proc *parent;
{
SX_ASSERT_XLOCKED(&proctree_lock);
PROC_LOCK_ASSERT(child, MA_OWNED);
if (child->p_pptr == parent)
return;
LIST_REMOVE(child, p_sibling);
LIST_INSERT_HEAD(&parent->p_children, child, p_sibling);
child->p_pptr = parent;
}
/*
* The next two functions are to handle adding/deleting items on the
* exit callout list
*
* at_exit():
* Take the arguments given and put them onto the exit callout list,
* However first make sure that it's not already there.
* returns 0 on success.
*/
int
at_exit(function)
exitlist_fn function;
{
struct exitlist *ep;
#ifdef INVARIANTS
/* Be noisy if the programmer has lost track of things */
if (rm_at_exit(function))
printf("WARNING: exit callout entry (%p) already present\n",
function);
#endif
ep = malloc(sizeof(*ep), M_ATEXIT, M_NOWAIT);
if (ep == NULL)
return (ENOMEM);
ep->function = function;
TAILQ_INSERT_TAIL(&exit_list, ep, next);
return (0);
}
/*
* Scan the exit callout list for the given item and remove it.
* Returns the number of items removed (0 or 1)
*/
int
rm_at_exit(function)
exitlist_fn function;
{
struct exitlist *ep;
TAILQ_FOREACH(ep, &exit_list, next) {
if (ep->function == function) {
TAILQ_REMOVE(&exit_list, ep, next);
free(ep, M_ATEXIT);
return(1);
}
}
return (0);
}
void check_sigacts (void)
{
struct proc *p = curproc;
struct sigacts *pss;
int s;
PROC_LOCK(p);
if (p->p_procsig->ps_refcnt == 1 &&
p->p_sigacts != &p->p_addr->u_sigacts) {
pss = p->p_sigacts;
s = splhigh();
p->p_addr->u_sigacts = *pss;
p->p_sigacts = &p->p_addr->u_sigacts;
splx(s);
FREE(pss, M_SUBPROC);
}
PROC_UNLOCK(p);
}
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