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freebsd-dev/sys/kern/kern_resource.c
Robert Watson 387d2c036b o Centralize inter-process access control, introducing: 
int p_can(p1, p2, operation, privused)

  which allows specification of subject process, object process,
  inter-process operation, and an optional call-by-reference privused
  flag, allowing the caller to determine if privilege was required
  for the call to succeed.  This allows jail, kern.ps_showallprocs and
  regular credential-based interaction checks to occur in one block of
  code.  Possible operations are P_CAN_SEE, P_CAN_SCHED, P_CAN_KILL,
  and P_CAN_DEBUG.  p_can currently breaks out as a wrapper to a
  series of static function checks in kern_prot, which should not
  be invoked directly.

o Commented out capabilities entries are included for some checks.

o Update most inter-process authorization to make use of p_can() instead
  of manual checks, PRISON_CHECK(), P_TRESPASS(), and
  kern.ps_showallprocs.

o Modify suser{,_xxx} to use const arguments, as it no longer modifies
  process flags due to the disabling of ASU.

o Modify some checks/errors in procfs so that ENOENT is returned instead
  of ESRCH, further improving concealment of processes that should not
  be visible to other processes.  Also introduce new access checks to
  improve hiding of processes for procfs_lookup(), procfs_getattr(),
  procfs_readdir().  Correct a bug reported by bp concerning not
  handling the CREATE case in procfs_lookup().  Remove volatile flag in
  procfs that caused apparently spurious qualifier warnigns (approved by
  bde).

o Add comment noting that ktrace() has not been updated, as its access
  control checks are different from ptrace(), whereas they should
  probably be the same.  Further discussion should happen on this topic.

Reviewed by:	bde, green, phk, freebsd-security, others
Approved by:	bde
Obtained from:	TrustedBSD Project
2000-08-30 04:49:09 +00:00

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/*-
* Copyright (c) 1982, 1986, 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_resource.c 8.5 (Berkeley) 1/21/94
* $FreeBSD$
*/
#include "opt_compat.h"
#include "opt_rlimit.h"
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/sysproto.h>
#include <sys/file.h>
#include <sys/resourcevar.h>
#include <sys/malloc.h>
#include <sys/proc.h>
#include <sys/time.h>
#include <vm/vm.h>
#include <vm/vm_param.h>
#include <sys/lock.h>
#include <vm/pmap.h>
#include <vm/vm_map.h>
static int donice __P((struct proc *curp, struct proc *chgp, int n));
/* dosetrlimit non-static: Needed by SysVR4 emulator */
int dosetrlimit __P((struct proc *p, u_int which, struct rlimit *limp));
/*
* Resource controls and accounting.
*/
#ifndef _SYS_SYSPROTO_H_
struct getpriority_args {
int which;
int who;
};
#endif
int
getpriority(curp, uap)
struct proc *curp;
register struct getpriority_args *uap;
{
register struct proc *p;
register int low = PRIO_MAX + 1;
switch (uap->which) {
case PRIO_PROCESS:
if (uap->who == 0)
p = curp;
else
p = pfind(uap->who);
if (p == 0)
break;
if (p_can(curp, p, P_CAN_SEE, NULL))
break;
low = p->p_nice;
break;
case PRIO_PGRP: {
register struct pgrp *pg;
if (uap->who == 0)
pg = curp->p_pgrp;
else if ((pg = pgfind(uap->who)) == NULL)
break;
LIST_FOREACH(p, &pg->pg_members, p_pglist) {
if (!p_can(curp, p, P_CAN_SEE, NULL) && p->p_nice < low)
low = p->p_nice;
}
break;
}
case PRIO_USER:
if (uap->who == 0)
uap->who = curp->p_ucred->cr_uid;
LIST_FOREACH(p, &allproc, p_list)
if (!p_can(curp, p, P_CAN_SEE, NULL) &&
p->p_ucred->cr_uid == uap->who &&
p->p_nice < low)
low = p->p_nice;
break;
default:
return (EINVAL);
}
if (low == PRIO_MAX + 1)
return (ESRCH);
curp->p_retval[0] = low;
return (0);
}
#ifndef _SYS_SYSPROTO_H_
struct setpriority_args {
int which;
int who;
int prio;
};
#endif
/* ARGSUSED */
int
setpriority(curp, uap)
struct proc *curp;
register struct setpriority_args *uap;
{
register struct proc *p;
int found = 0, error = 0;
switch (uap->which) {
case PRIO_PROCESS:
if (uap->who == 0)
p = curp;
else
p = pfind(uap->who);
if (p == 0)
break;
if (p_can(curp, p, P_CAN_SEE, NULL))
break;
error = donice(curp, p, uap->prio);
found++;
break;
case PRIO_PGRP: {
register struct pgrp *pg;
if (uap->who == 0)
pg = curp->p_pgrp;
else if ((pg = pgfind(uap->who)) == NULL)
break;
LIST_FOREACH(p, &pg->pg_members, p_pglist) {
if (!p_can(curp, p, P_CAN_SEE, NULL)) {
error = donice(curp, p, uap->prio);
found++;
}
}
break;
}
case PRIO_USER:
if (uap->who == 0)
uap->who = curp->p_ucred->cr_uid;
LIST_FOREACH(p, &allproc, p_list)
if (p->p_ucred->cr_uid == uap->who &&
!p_can(curp, p, P_CAN_SEE, NULL)) {
error = donice(curp, p, uap->prio);
found++;
}
break;
default:
return (EINVAL);
}
if (found == 0)
return (ESRCH);
return (error);
}
static int
donice(curp, chgp, n)
register struct proc *curp, *chgp;
register int n;
{
int error;
if ((error = p_can(curp, chgp, P_CAN_SCHED, NULL)))
return (error);
if (n > PRIO_MAX)
n = PRIO_MAX;
if (n < PRIO_MIN)
n = PRIO_MIN;
if (n < chgp->p_nice && suser(curp))
return (EACCES);
chgp->p_nice = n;
(void)resetpriority(chgp);
return (0);
}
/* rtprio system call */
#ifndef _SYS_SYSPROTO_H_
struct rtprio_args {
int function;
pid_t pid;
struct rtprio *rtp;
};
#endif
/*
* Set realtime priority
*/
/* ARGSUSED */
int
rtprio(curp, uap)
struct proc *curp;
register struct rtprio_args *uap;
{
register struct proc *p;
struct rtprio rtp;
int error;
error = copyin(uap->rtp, &rtp, sizeof(struct rtprio));
if (error)
return (error);
if (uap->pid == 0)
p = curp;
else
p = pfind(uap->pid);
if (p == 0)
return (ESRCH);
switch (uap->function) {
case RTP_LOOKUP:
return (copyout(&p->p_rtprio, uap->rtp, sizeof(struct rtprio)));
case RTP_SET:
if ((error = p_can(curp, p, P_CAN_SCHED, NULL)))
return (error);
/* disallow setting rtprio in most cases if not superuser */
if (suser(curp) != 0) {
/* can't set someone else's */
if (uap->pid)
return (EPERM);
/* can't set realtime priority */
/*
* Realtime priority has to be restricted for reasons which should be
* obvious. However, for idle priority, there is a potential for
* system deadlock if an idleprio process gains a lock on a resource
* that other processes need (and the idleprio process can't run
* due to a CPU-bound normal process). Fix me! XXX
*/
#if 0
if (RTP_PRIO_IS_REALTIME(rtp.type))
#endif
if (rtp.type != RTP_PRIO_NORMAL)
return (EPERM);
}
switch (rtp.type) {
#ifdef RTP_PRIO_FIFO
case RTP_PRIO_FIFO:
#endif
case RTP_PRIO_REALTIME:
case RTP_PRIO_NORMAL:
case RTP_PRIO_IDLE:
if (rtp.prio > RTP_PRIO_MAX)
return (EINVAL);
p->p_rtprio = rtp;
return (0);
default:
return (EINVAL);
}
default:
return (EINVAL);
}
}
#if defined(COMPAT_43) || defined(COMPAT_SUNOS)
#ifndef _SYS_SYSPROTO_H_
struct osetrlimit_args {
u_int which;
struct orlimit *rlp;
};
#endif
/* ARGSUSED */
int
osetrlimit(p, uap)
struct proc *p;
register struct osetrlimit_args *uap;
{
struct orlimit olim;
struct rlimit lim;
int error;
if ((error =
copyin((caddr_t)uap->rlp, (caddr_t)&olim, sizeof(struct orlimit))))
return (error);
lim.rlim_cur = olim.rlim_cur;
lim.rlim_max = olim.rlim_max;
return (dosetrlimit(p, uap->which, &lim));
}
#ifndef _SYS_SYSPROTO_H_
struct ogetrlimit_args {
u_int which;
struct orlimit *rlp;
};
#endif
/* ARGSUSED */
int
ogetrlimit(p, uap)
struct proc *p;
register struct ogetrlimit_args *uap;
{
struct orlimit olim;
if (uap->which >= RLIM_NLIMITS)
return (EINVAL);
olim.rlim_cur = p->p_rlimit[uap->which].rlim_cur;
if (olim.rlim_cur == -1)
olim.rlim_cur = 0x7fffffff;
olim.rlim_max = p->p_rlimit[uap->which].rlim_max;
if (olim.rlim_max == -1)
olim.rlim_max = 0x7fffffff;
return (copyout((caddr_t)&olim, (caddr_t)uap->rlp, sizeof(olim)));
}
#endif /* COMPAT_43 || COMPAT_SUNOS */
#ifndef _SYS_SYSPROTO_H_
struct __setrlimit_args {
u_int which;
struct rlimit *rlp;
};
#endif
/* ARGSUSED */
int
setrlimit(p, uap)
struct proc *p;
register struct __setrlimit_args *uap;
{
struct rlimit alim;
int error;
if ((error =
copyin((caddr_t)uap->rlp, (caddr_t)&alim, sizeof (struct rlimit))))
return (error);
return (dosetrlimit(p, uap->which, &alim));
}
int
dosetrlimit(p, which, limp)
struct proc *p;
u_int which;
struct rlimit *limp;
{
register struct rlimit *alimp;
int error;
if (which >= RLIM_NLIMITS)
return (EINVAL);
alimp = &p->p_rlimit[which];
/*
* Preserve historical bugs by treating negative limits as unsigned.
*/
if (limp->rlim_cur < 0)
limp->rlim_cur = RLIM_INFINITY;
if (limp->rlim_max < 0)
limp->rlim_max = RLIM_INFINITY;
if (limp->rlim_cur > alimp->rlim_max ||
limp->rlim_max > alimp->rlim_max)
if ((error = suser_xxx(0, p, PRISON_ROOT)))
return (error);
if (limp->rlim_cur > limp->rlim_max)
limp->rlim_cur = limp->rlim_max;
if (p->p_limit->p_refcnt > 1 &&
(p->p_limit->p_lflags & PL_SHAREMOD) == 0) {
p->p_limit->p_refcnt--;
p->p_limit = limcopy(p->p_limit);
alimp = &p->p_rlimit[which];
}
switch (which) {
case RLIMIT_CPU:
if (limp->rlim_cur > RLIM_INFINITY / (rlim_t)1000000)
p->p_limit->p_cpulimit = RLIM_INFINITY;
else
p->p_limit->p_cpulimit =
(rlim_t)1000000 * limp->rlim_cur;
break;
case RLIMIT_DATA:
if (limp->rlim_cur > MAXDSIZ)
limp->rlim_cur = MAXDSIZ;
if (limp->rlim_max > MAXDSIZ)
limp->rlim_max = MAXDSIZ;
break;
case RLIMIT_STACK:
if (limp->rlim_cur > MAXSSIZ)
limp->rlim_cur = MAXSSIZ;
if (limp->rlim_max > MAXSSIZ)
limp->rlim_max = MAXSSIZ;
/*
* Stack is allocated to the max at exec time with only
* "rlim_cur" bytes accessible. If stack limit is going
* up make more accessible, if going down make inaccessible.
*/
if (limp->rlim_cur != alimp->rlim_cur) {
vm_offset_t addr;
vm_size_t size;
vm_prot_t prot;
if (limp->rlim_cur > alimp->rlim_cur) {
prot = VM_PROT_ALL;
size = limp->rlim_cur - alimp->rlim_cur;
addr = USRSTACK - limp->rlim_cur;
} else {
prot = VM_PROT_NONE;
size = alimp->rlim_cur - limp->rlim_cur;
addr = USRSTACK - alimp->rlim_cur;
}
addr = trunc_page(addr);
size = round_page(size);
(void) vm_map_protect(&p->p_vmspace->vm_map,
addr, addr+size, prot, FALSE);
}
break;
case RLIMIT_NOFILE:
if (limp->rlim_cur > maxfilesperproc)
limp->rlim_cur = maxfilesperproc;
if (limp->rlim_max > maxfilesperproc)
limp->rlim_max = maxfilesperproc;
break;
case RLIMIT_NPROC:
if (limp->rlim_cur > maxprocperuid)
limp->rlim_cur = maxprocperuid;
if (limp->rlim_max > maxprocperuid)
limp->rlim_max = maxprocperuid;
break;
}
*alimp = *limp;
return (0);
}
#ifndef _SYS_SYSPROTO_H_
struct __getrlimit_args {
u_int which;
struct rlimit *rlp;
};
#endif
/* ARGSUSED */
int
getrlimit(p, uap)
struct proc *p;
register struct __getrlimit_args *uap;
{
if (uap->which >= RLIM_NLIMITS)
return (EINVAL);
return (copyout((caddr_t)&p->p_rlimit[uap->which], (caddr_t)uap->rlp,
sizeof (struct rlimit)));
}
/*
* Transform the running time and tick information in proc p into user,
* system, and interrupt time usage.
*/
void
calcru(p, up, sp, ip)
struct proc *p;
struct timeval *up;
struct timeval *sp;
struct timeval *ip;
{
/* {user, system, interrupt, total} {ticks, usec}; previous tu: */
u_int64_t ut, uu, st, su, it, iu, tt, tu, ptu;
int s;
struct timeval tv;
/* XXX: why spl-protect ? worst case is an off-by-one report */
s = splstatclock();
ut = p->p_uticks;
st = p->p_sticks;
it = p->p_iticks;
splx(s);
tt = ut + st + it;
if (tt == 0) {
st = 1;
tt = 1;
}
tu = p->p_runtime;
if (p == curproc) {
/*
* Adjust for the current time slice. This is actually fairly
* important since the error here is on the order of a time
* quantum, which is much greater than the sampling error.
*/
microuptime(&tv);
if (timevalcmp(&tv, &switchtime, <))
printf("microuptime() went backwards (%ld.%06ld -> %ld.%06ld)\n",
switchtime.tv_sec, switchtime.tv_usec,
tv.tv_sec, tv.tv_usec);
else
tu += (tv.tv_usec - switchtime.tv_usec) +
(tv.tv_sec - switchtime.tv_sec) * (int64_t)1000000;
}
ptu = p->p_uu + p->p_su + p->p_iu;
if (tu < ptu || (int64_t)tu < 0) {
/* XXX no %qd in kernel. Truncate. */
printf("calcru: negative time of %ld usec for pid %d (%s)\n",
(long)tu, p->p_pid, p->p_comm);
tu = ptu;
}
/* Subdivide tu. */
uu = (tu * ut) / tt;
su = (tu * st) / tt;
iu = tu - uu - su;
/* Enforce monotonicity. */
if (uu < p->p_uu || su < p->p_su || iu < p->p_iu) {
if (uu < p->p_uu)
uu = p->p_uu;
else if (uu + p->p_su + p->p_iu > tu)
uu = tu - p->p_su - p->p_iu;
if (st == 0)
su = p->p_su;
else {
su = ((tu - uu) * st) / (st + it);
if (su < p->p_su)
su = p->p_su;
else if (uu + su + p->p_iu > tu)
su = tu - uu - p->p_iu;
}
KASSERT(uu + su + p->p_iu <= tu,
("calcru: monotonisation botch 1"));
iu = tu - uu - su;
KASSERT(iu >= p->p_iu,
("calcru: monotonisation botch 2"));
}
p->p_uu = uu;
p->p_su = su;
p->p_iu = iu;
up->tv_sec = uu / 1000000;
up->tv_usec = uu % 1000000;
sp->tv_sec = su / 1000000;
sp->tv_usec = su % 1000000;
if (ip != NULL) {
ip->tv_sec = iu / 1000000;
ip->tv_usec = iu % 1000000;
}
}
#ifndef _SYS_SYSPROTO_H_
struct getrusage_args {
int who;
struct rusage *rusage;
};
#endif
/* ARGSUSED */
int
getrusage(p, uap)
register struct proc *p;
register struct getrusage_args *uap;
{
register struct rusage *rup;
switch (uap->who) {
case RUSAGE_SELF:
rup = &p->p_stats->p_ru;
calcru(p, &rup->ru_utime, &rup->ru_stime, NULL);
break;
case RUSAGE_CHILDREN:
rup = &p->p_stats->p_cru;
break;
default:
return (EINVAL);
}
return (copyout((caddr_t)rup, (caddr_t)uap->rusage,
sizeof (struct rusage)));
}
void
ruadd(ru, ru2)
register struct rusage *ru, *ru2;
{
register long *ip, *ip2;
register int i;
timevaladd(&ru->ru_utime, &ru2->ru_utime);
timevaladd(&ru->ru_stime, &ru2->ru_stime);
if (ru->ru_maxrss < ru2->ru_maxrss)
ru->ru_maxrss = ru2->ru_maxrss;
ip = &ru->ru_first; ip2 = &ru2->ru_first;
for (i = &ru->ru_last - &ru->ru_first; i >= 0; i--)
*ip++ += *ip2++;
}
/*
* Make a copy of the plimit structure.
* We share these structures copy-on-write after fork,
* and copy when a limit is changed.
*/
struct plimit *
limcopy(lim)
struct plimit *lim;
{
register struct plimit *copy;
MALLOC(copy, struct plimit *, sizeof(struct plimit),
M_SUBPROC, M_WAITOK);
bcopy(lim->pl_rlimit, copy->pl_rlimit, sizeof(struct plimit));
copy->p_lflags = 0;
copy->p_refcnt = 1;
return (copy);
}
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