1 /* $OpenBSD: kern_resource.c,v 1.84 2024/06/03 12:48:25 claudio Exp $ */
2 /* $NetBSD: kern_resource.c,v 1.38 1996/10/23 07:19:38 matthias Exp $ */
3
4 /*-
5 * Copyright (c) 1982, 1986, 1991, 1993
6 * The Regents of the University of California. All rights reserved.
7 * (c) UNIX System Laboratories, Inc.
8 * All or some portions of this file are derived from material licensed
9 * to the University of California by American Telephone and Telegraph
10 * Co. or Unix System Laboratories, Inc. and are reproduced herein with
11 * the permission of UNIX System Laboratories, Inc.
12 *
13 * Redistribution and use in source and binary forms, with or without
14 * modification, are permitted provided that the following conditions
15 * are met:
16 * 1. Redistributions of source code must retain the above copyright
17 * notice, this list of conditions and the following disclaimer.
18 * 2. Redistributions in binary form must reproduce the above copyright
19 * notice, this list of conditions and the following disclaimer in the
20 * documentation and/or other materials provided with the distribution.
21 * 3. Neither the name of the University nor the names of its contributors
22 * may be used to endorse or promote products derived from this software
23 * without specific prior written permission.
24 *
25 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
26 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
27 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
28 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
29 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
30 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
31 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
32 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
33 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
34 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
35 * SUCH DAMAGE.
36 *
37 * @(#)kern_resource.c 8.5 (Berkeley) 1/21/94
38 */
39
40 #include <sys/param.h>
41 #include <sys/systm.h>
42 #include <sys/kernel.h>
43 #include <sys/file.h>
44 #include <sys/resourcevar.h>
45 #include <sys/pool.h>
46 #include <sys/proc.h>
47 #include <sys/ktrace.h>
48 #include <sys/sched.h>
49 #include <sys/signalvar.h>
50
51 #include <sys/mount.h>
52 #include <sys/syscallargs.h>
53
54 #include <uvm/uvm_extern.h>
55 #include <uvm/uvm.h>
56
57 /* Resource usage check interval in msec */
58 #define RUCHECK_INTERVAL 1000
59
60 /* SIGXCPU interval in seconds of process runtime */
61 #define SIGXCPU_INTERVAL 5
62
63 struct plimit *lim_copy(struct plimit *);
64 struct plimit *lim_write_begin(void);
65 void lim_write_commit(struct plimit *);
66
67 void tuagg_sub(struct tusage *, struct proc *, const struct timespec *);
68
69 /*
70 * Patchable maximum data and stack limits.
71 */
72 rlim_t maxdmap = MAXDSIZ;
73 rlim_t maxsmap = MAXSSIZ;
74
75 /*
76 * Serializes resource limit updates.
77 * This lock has to be held together with ps_mtx when updating
78 * the process' ps_limit.
79 */
80 struct rwlock rlimit_lock = RWLOCK_INITIALIZER("rlimitlk");
81
82 /*
83 * Resource controls and accounting.
84 */
85
86 int
sys_getpriority(struct proc * curp,void * v,register_t * retval)87 sys_getpriority(struct proc *curp, void *v, register_t *retval)
88 {
89 struct sys_getpriority_args /* {
90 syscallarg(int) which;
91 syscallarg(id_t) who;
92 } */ *uap = v;
93 struct process *pr;
94 int low = NZERO + PRIO_MAX + 1;
95
96 switch (SCARG(uap, which)) {
97
98 case PRIO_PROCESS:
99 if (SCARG(uap, who) == 0)
100 pr = curp->p_p;
101 else
102 pr = prfind(SCARG(uap, who));
103 if (pr == NULL)
104 break;
105 if (pr->ps_nice < low)
106 low = pr->ps_nice;
107 break;
108
109 case PRIO_PGRP: {
110 struct pgrp *pg;
111
112 if (SCARG(uap, who) == 0)
113 pg = curp->p_p->ps_pgrp;
114 else if ((pg = pgfind(SCARG(uap, who))) == NULL)
115 break;
116 LIST_FOREACH(pr, &pg->pg_members, ps_pglist)
117 if (pr->ps_nice < low)
118 low = pr->ps_nice;
119 break;
120 }
121
122 case PRIO_USER:
123 if (SCARG(uap, who) == 0)
124 SCARG(uap, who) = curp->p_ucred->cr_uid;
125 LIST_FOREACH(pr, &allprocess, ps_list)
126 if (pr->ps_ucred->cr_uid == SCARG(uap, who) &&
127 pr->ps_nice < low)
128 low = pr->ps_nice;
129 break;
130
131 default:
132 return (EINVAL);
133 }
134 if (low == NZERO + PRIO_MAX + 1)
135 return (ESRCH);
136 *retval = low - NZERO;
137 return (0);
138 }
139
140 int
sys_setpriority(struct proc * curp,void * v,register_t * retval)141 sys_setpriority(struct proc *curp, void *v, register_t *retval)
142 {
143 struct sys_setpriority_args /* {
144 syscallarg(int) which;
145 syscallarg(id_t) who;
146 syscallarg(int) prio;
147 } */ *uap = v;
148 struct process *pr;
149 int found = 0, error = 0;
150
151 switch (SCARG(uap, which)) {
152
153 case PRIO_PROCESS:
154 if (SCARG(uap, who) == 0)
155 pr = curp->p_p;
156 else
157 pr = prfind(SCARG(uap, who));
158 if (pr == NULL)
159 break;
160 error = donice(curp, pr, SCARG(uap, prio));
161 found = 1;
162 break;
163
164 case PRIO_PGRP: {
165 struct pgrp *pg;
166
167 if (SCARG(uap, who) == 0)
168 pg = curp->p_p->ps_pgrp;
169 else if ((pg = pgfind(SCARG(uap, who))) == NULL)
170 break;
171 LIST_FOREACH(pr, &pg->pg_members, ps_pglist) {
172 error = donice(curp, pr, SCARG(uap, prio));
173 found = 1;
174 }
175 break;
176 }
177
178 case PRIO_USER:
179 if (SCARG(uap, who) == 0)
180 SCARG(uap, who) = curp->p_ucred->cr_uid;
181 LIST_FOREACH(pr, &allprocess, ps_list)
182 if (pr->ps_ucred->cr_uid == SCARG(uap, who)) {
183 error = donice(curp, pr, SCARG(uap, prio));
184 found = 1;
185 }
186 break;
187
188 default:
189 return (EINVAL);
190 }
191 if (!found)
192 return (ESRCH);
193 return (error);
194 }
195
196 int
donice(struct proc * curp,struct process * chgpr,int n)197 donice(struct proc *curp, struct process *chgpr, int n)
198 {
199 struct ucred *ucred = curp->p_ucred;
200 struct proc *p;
201
202 if (ucred->cr_uid != 0 && ucred->cr_ruid != 0 &&
203 ucred->cr_uid != chgpr->ps_ucred->cr_uid &&
204 ucred->cr_ruid != chgpr->ps_ucred->cr_uid)
205 return (EPERM);
206 if (n > PRIO_MAX)
207 n = PRIO_MAX;
208 if (n < PRIO_MIN)
209 n = PRIO_MIN;
210 n += NZERO;
211 if (n < chgpr->ps_nice && suser(curp))
212 return (EACCES);
213 chgpr->ps_nice = n;
214 mtx_enter(&chgpr->ps_mtx);
215 SCHED_LOCK();
216 TAILQ_FOREACH(p, &chgpr->ps_threads, p_thr_link) {
217 setpriority(p, p->p_estcpu, n);
218 }
219 SCHED_UNLOCK();
220 mtx_leave(&chgpr->ps_mtx);
221 return (0);
222 }
223
224 int
sys_setrlimit(struct proc * p,void * v,register_t * retval)225 sys_setrlimit(struct proc *p, void *v, register_t *retval)
226 {
227 struct sys_setrlimit_args /* {
228 syscallarg(int) which;
229 syscallarg(const struct rlimit *) rlp;
230 } */ *uap = v;
231 struct rlimit alim;
232 int error;
233
234 error = copyin((caddr_t)SCARG(uap, rlp), (caddr_t)&alim,
235 sizeof (struct rlimit));
236 if (error)
237 return (error);
238 #ifdef KTRACE
239 if (KTRPOINT(p, KTR_STRUCT))
240 ktrrlimit(p, &alim);
241 #endif
242 return (dosetrlimit(p, SCARG(uap, which), &alim));
243 }
244
245 int
dosetrlimit(struct proc * p,u_int which,struct rlimit * limp)246 dosetrlimit(struct proc *p, u_int which, struct rlimit *limp)
247 {
248 struct rlimit *alimp;
249 struct plimit *limit;
250 rlim_t maxlim;
251 int error;
252
253 if (which >= RLIM_NLIMITS || limp->rlim_cur > limp->rlim_max)
254 return (EINVAL);
255
256 rw_enter_write(&rlimit_lock);
257
258 alimp = &p->p_p->ps_limit->pl_rlimit[which];
259 if (limp->rlim_max > alimp->rlim_max) {
260 if ((error = suser(p)) != 0) {
261 rw_exit_write(&rlimit_lock);
262 return (error);
263 }
264 }
265
266 /* Get exclusive write access to the limit structure. */
267 limit = lim_write_begin();
268 alimp = &limit->pl_rlimit[which];
269
270 switch (which) {
271 case RLIMIT_DATA:
272 maxlim = maxdmap;
273 break;
274 case RLIMIT_STACK:
275 maxlim = maxsmap;
276 break;
277 case RLIMIT_NOFILE:
278 maxlim = maxfiles;
279 break;
280 case RLIMIT_NPROC:
281 maxlim = maxprocess;
282 break;
283 default:
284 maxlim = RLIM_INFINITY;
285 break;
286 }
287
288 if (limp->rlim_max > maxlim)
289 limp->rlim_max = maxlim;
290 if (limp->rlim_cur > limp->rlim_max)
291 limp->rlim_cur = limp->rlim_max;
292
293 if (which == RLIMIT_CPU && limp->rlim_cur != RLIM_INFINITY &&
294 alimp->rlim_cur == RLIM_INFINITY)
295 timeout_add_msec(&p->p_p->ps_rucheck_to, RUCHECK_INTERVAL);
296
297 if (which == RLIMIT_STACK) {
298 /*
299 * Stack is allocated to the max at exec time with only
300 * "rlim_cur" bytes accessible. If stack limit is going
301 * up make more accessible, if going down make inaccessible.
302 */
303 if (limp->rlim_cur != alimp->rlim_cur) {
304 vaddr_t addr;
305 vsize_t size;
306 vm_prot_t prot;
307 struct vmspace *vm = p->p_vmspace;
308
309 if (limp->rlim_cur > alimp->rlim_cur) {
310 prot = PROT_READ | PROT_WRITE;
311 size = limp->rlim_cur - alimp->rlim_cur;
312 #ifdef MACHINE_STACK_GROWS_UP
313 addr = (vaddr_t)vm->vm_maxsaddr +
314 alimp->rlim_cur;
315 #else
316 addr = (vaddr_t)vm->vm_minsaddr -
317 limp->rlim_cur;
318 #endif
319 } else {
320 prot = PROT_NONE;
321 size = alimp->rlim_cur - limp->rlim_cur;
322 #ifdef MACHINE_STACK_GROWS_UP
323 addr = (vaddr_t)vm->vm_maxsaddr +
324 limp->rlim_cur;
325 #else
326 addr = (vaddr_t)vm->vm_minsaddr -
327 alimp->rlim_cur;
328 #endif
329 }
330 addr = trunc_page(addr);
331 size = round_page(size);
332 KERNEL_LOCK();
333 (void) uvm_map_protect(&vm->vm_map, addr,
334 addr+size, prot, UVM_ET_STACK, FALSE, FALSE);
335 KERNEL_UNLOCK();
336 }
337 }
338
339 *alimp = *limp;
340
341 lim_write_commit(limit);
342 rw_exit_write(&rlimit_lock);
343
344 return (0);
345 }
346
347 int
sys_getrlimit(struct proc * p,void * v,register_t * retval)348 sys_getrlimit(struct proc *p, void *v, register_t *retval)
349 {
350 struct sys_getrlimit_args /* {
351 syscallarg(int) which;
352 syscallarg(struct rlimit *) rlp;
353 } */ *uap = v;
354 struct plimit *limit;
355 struct rlimit alimp;
356 int error;
357
358 if (SCARG(uap, which) < 0 || SCARG(uap, which) >= RLIM_NLIMITS)
359 return (EINVAL);
360 limit = lim_read_enter();
361 alimp = limit->pl_rlimit[SCARG(uap, which)];
362 lim_read_leave(limit);
363 error = copyout(&alimp, SCARG(uap, rlp), sizeof(struct rlimit));
364 #ifdef KTRACE
365 if (error == 0 && KTRPOINT(p, KTR_STRUCT))
366 ktrrlimit(p, &alimp);
367 #endif
368 return (error);
369 }
370
371 void
tuagg_sub(struct tusage * tup,struct proc * p,const struct timespec * ts)372 tuagg_sub(struct tusage *tup, struct proc *p, const struct timespec *ts)
373 {
374 if (ts != NULL)
375 timespecadd(&tup->tu_runtime, ts, &tup->tu_runtime);
376 tup->tu_uticks += p->p_uticks;
377 tup->tu_sticks += p->p_sticks;
378 tup->tu_iticks += p->p_iticks;
379 }
380
381 /*
382 * Aggregate a single thread's immediate time counts into the running
383 * totals for the thread and process
384 */
385 void
tuagg_locked(struct process * pr,struct proc * p,const struct timespec * ts)386 tuagg_locked(struct process *pr, struct proc *p, const struct timespec *ts)
387 {
388 tuagg_sub(&pr->ps_tu, p, ts);
389 tuagg_sub(&p->p_tu, p, ts);
390 p->p_uticks = 0;
391 p->p_sticks = 0;
392 p->p_iticks = 0;
393 }
394
395 void
tuagg(struct process * pr,struct proc * p)396 tuagg(struct process *pr, struct proc *p)
397 {
398 SCHED_LOCK();
399 tuagg_locked(pr, p, NULL);
400 SCHED_UNLOCK();
401 }
402
403 /*
404 * Transform the running time and tick information in a struct tusage
405 * into user, system, and interrupt time usage.
406 */
407 void
calctsru(struct tusage * tup,struct timespec * up,struct timespec * sp,struct timespec * ip)408 calctsru(struct tusage *tup, struct timespec *up, struct timespec *sp,
409 struct timespec *ip)
410 {
411 u_quad_t st, ut, it;
412
413 st = tup->tu_sticks;
414 ut = tup->tu_uticks;
415 it = tup->tu_iticks;
416
417 if (st + ut + it == 0) {
418 timespecclear(up);
419 timespecclear(sp);
420 if (ip != NULL)
421 timespecclear(ip);
422 return;
423 }
424
425 st = st * 1000000000 / stathz;
426 sp->tv_sec = st / 1000000000;
427 sp->tv_nsec = st % 1000000000;
428 ut = ut * 1000000000 / stathz;
429 up->tv_sec = ut / 1000000000;
430 up->tv_nsec = ut % 1000000000;
431 if (ip != NULL) {
432 it = it * 1000000000 / stathz;
433 ip->tv_sec = it / 1000000000;
434 ip->tv_nsec = it % 1000000000;
435 }
436 }
437
438 void
calcru(struct tusage * tup,struct timeval * up,struct timeval * sp,struct timeval * ip)439 calcru(struct tusage *tup, struct timeval *up, struct timeval *sp,
440 struct timeval *ip)
441 {
442 struct timespec u, s, i;
443
444 calctsru(tup, &u, &s, ip != NULL ? &i : NULL);
445 TIMESPEC_TO_TIMEVAL(up, &u);
446 TIMESPEC_TO_TIMEVAL(sp, &s);
447 if (ip != NULL)
448 TIMESPEC_TO_TIMEVAL(ip, &i);
449 }
450
451 int
sys_getrusage(struct proc * p,void * v,register_t * retval)452 sys_getrusage(struct proc *p, void *v, register_t *retval)
453 {
454 struct sys_getrusage_args /* {
455 syscallarg(int) who;
456 syscallarg(struct rusage *) rusage;
457 } */ *uap = v;
458 struct rusage ru;
459 int error;
460
461 error = dogetrusage(p, SCARG(uap, who), &ru);
462 if (error == 0) {
463 error = copyout(&ru, SCARG(uap, rusage), sizeof(ru));
464 #ifdef KTRACE
465 if (error == 0 && KTRPOINT(p, KTR_STRUCT))
466 ktrrusage(p, &ru);
467 #endif
468 }
469 return (error);
470 }
471
472 int
dogetrusage(struct proc * p,int who,struct rusage * rup)473 dogetrusage(struct proc *p, int who, struct rusage *rup)
474 {
475 struct process *pr = p->p_p;
476 struct proc *q;
477
478 KERNEL_ASSERT_LOCKED();
479
480 switch (who) {
481 case RUSAGE_SELF:
482 /* start with the sum of dead threads, if any */
483 if (pr->ps_ru != NULL)
484 *rup = *pr->ps_ru;
485 else
486 memset(rup, 0, sizeof(*rup));
487
488 /* add on all living threads */
489 TAILQ_FOREACH(q, &pr->ps_threads, p_thr_link) {
490 ruadd(rup, &q->p_ru);
491 tuagg(pr, q);
492 }
493
494 calcru(&pr->ps_tu, &rup->ru_utime, &rup->ru_stime, NULL);
495 break;
496
497 case RUSAGE_THREAD:
498 *rup = p->p_ru;
499 calcru(&p->p_tu, &rup->ru_utime, &rup->ru_stime, NULL);
500 break;
501
502 case RUSAGE_CHILDREN:
503 *rup = pr->ps_cru;
504 break;
505
506 default:
507 return (EINVAL);
508 }
509 return (0);
510 }
511
512 void
ruadd(struct rusage * ru,struct rusage * ru2)513 ruadd(struct rusage *ru, struct rusage *ru2)
514 {
515 long *ip, *ip2;
516 int i;
517
518 timeradd(&ru->ru_utime, &ru2->ru_utime, &ru->ru_utime);
519 timeradd(&ru->ru_stime, &ru2->ru_stime, &ru->ru_stime);
520 if (ru->ru_maxrss < ru2->ru_maxrss)
521 ru->ru_maxrss = ru2->ru_maxrss;
522 ip = &ru->ru_first; ip2 = &ru2->ru_first;
523 for (i = &ru->ru_last - &ru->ru_first; i >= 0; i--)
524 *ip++ += *ip2++;
525 }
526
527 /*
528 * Check if the process exceeds its cpu resource allocation.
529 * If over max, kill it.
530 */
531 void
rucheck(void * arg)532 rucheck(void *arg)
533 {
534 struct rlimit rlim;
535 struct process *pr = arg;
536 time_t runtime;
537
538 KERNEL_ASSERT_LOCKED();
539
540 SCHED_LOCK();
541 runtime = pr->ps_tu.tu_runtime.tv_sec;
542 SCHED_UNLOCK();
543
544 mtx_enter(&pr->ps_mtx);
545 rlim = pr->ps_limit->pl_rlimit[RLIMIT_CPU];
546 mtx_leave(&pr->ps_mtx);
547
548 if ((rlim_t)runtime >= rlim.rlim_cur) {
549 if ((rlim_t)runtime >= rlim.rlim_max) {
550 prsignal(pr, SIGKILL);
551 } else if (runtime >= pr->ps_nextxcpu) {
552 prsignal(pr, SIGXCPU);
553 pr->ps_nextxcpu = runtime + SIGXCPU_INTERVAL;
554 }
555 }
556
557 timeout_add_msec(&pr->ps_rucheck_to, RUCHECK_INTERVAL);
558 }
559
560 struct pool plimit_pool;
561
562 void
lim_startup(struct plimit * limit0)563 lim_startup(struct plimit *limit0)
564 {
565 rlim_t lim;
566 int i;
567
568 pool_init(&plimit_pool, sizeof(struct plimit), 0, IPL_MPFLOOR,
569 PR_WAITOK, "plimitpl", NULL);
570
571 for (i = 0; i < nitems(limit0->pl_rlimit); i++)
572 limit0->pl_rlimit[i].rlim_cur =
573 limit0->pl_rlimit[i].rlim_max = RLIM_INFINITY;
574 limit0->pl_rlimit[RLIMIT_NOFILE].rlim_cur = NOFILE;
575 limit0->pl_rlimit[RLIMIT_NOFILE].rlim_max = MIN(NOFILE_MAX,
576 (maxfiles - NOFILE > NOFILE) ? maxfiles - NOFILE : NOFILE);
577 limit0->pl_rlimit[RLIMIT_NPROC].rlim_cur = MAXUPRC;
578 lim = ptoa(uvmexp.free);
579 limit0->pl_rlimit[RLIMIT_RSS].rlim_max = lim;
580 lim = ptoa(64*1024); /* Default to very low */
581 limit0->pl_rlimit[RLIMIT_MEMLOCK].rlim_max = lim;
582 limit0->pl_rlimit[RLIMIT_MEMLOCK].rlim_cur = lim / 3;
583 refcnt_init(&limit0->pl_refcnt);
584 }
585
586 /*
587 * Make a copy of the plimit structure.
588 * We share these structures copy-on-write after fork,
589 * and copy when a limit is changed.
590 */
591 struct plimit *
lim_copy(struct plimit * lim)592 lim_copy(struct plimit *lim)
593 {
594 struct plimit *newlim;
595
596 newlim = pool_get(&plimit_pool, PR_WAITOK);
597 memcpy(newlim->pl_rlimit, lim->pl_rlimit,
598 sizeof(struct rlimit) * RLIM_NLIMITS);
599 refcnt_init(&newlim->pl_refcnt);
600 return (newlim);
601 }
602
603 void
lim_free(struct plimit * lim)604 lim_free(struct plimit *lim)
605 {
606 if (refcnt_rele(&lim->pl_refcnt) == 0)
607 return;
608 pool_put(&plimit_pool, lim);
609 }
610
611 void
lim_fork(struct process * parent,struct process * child)612 lim_fork(struct process *parent, struct process *child)
613 {
614 struct plimit *limit;
615
616 mtx_enter(&parent->ps_mtx);
617 limit = parent->ps_limit;
618 refcnt_take(&limit->pl_refcnt);
619 mtx_leave(&parent->ps_mtx);
620
621 child->ps_limit = limit;
622
623 if (limit->pl_rlimit[RLIMIT_CPU].rlim_cur != RLIM_INFINITY)
624 timeout_add_msec(&child->ps_rucheck_to, RUCHECK_INTERVAL);
625 }
626
627 /*
628 * Return an exclusive write reference to the process' resource limit structure.
629 * The caller has to release the structure by calling lim_write_commit().
630 *
631 * This invalidates any plimit read reference held by the calling thread.
632 */
633 struct plimit *
lim_write_begin(void)634 lim_write_begin(void)
635 {
636 struct plimit *limit;
637 struct proc *p = curproc;
638
639 rw_assert_wrlock(&rlimit_lock);
640
641 if (p->p_limit != NULL)
642 lim_free(p->p_limit);
643 p->p_limit = NULL;
644
645 /*
646 * It is safe to access ps_limit here without holding ps_mtx
647 * because rlimit_lock excludes other writers.
648 */
649
650 limit = p->p_p->ps_limit;
651 if (P_HASSIBLING(p) || refcnt_shared(&limit->pl_refcnt))
652 limit = lim_copy(limit);
653
654 return (limit);
655 }
656
657 /*
658 * Finish exclusive write access to the plimit structure.
659 * This makes the structure visible to other threads in the process.
660 */
661 void
lim_write_commit(struct plimit * limit)662 lim_write_commit(struct plimit *limit)
663 {
664 struct plimit *olimit;
665 struct proc *p = curproc;
666
667 rw_assert_wrlock(&rlimit_lock);
668
669 if (limit != p->p_p->ps_limit) {
670 mtx_enter(&p->p_p->ps_mtx);
671 olimit = p->p_p->ps_limit;
672 p->p_p->ps_limit = limit;
673 mtx_leave(&p->p_p->ps_mtx);
674
675 lim_free(olimit);
676 }
677 }
678
679 /*
680 * Begin read access to the process' resource limit structure.
681 * The access has to be finished by calling lim_read_leave().
682 *
683 * Sections denoted by lim_read_enter() and lim_read_leave() cannot nest.
684 */
685 struct plimit *
lim_read_enter(void)686 lim_read_enter(void)
687 {
688 struct plimit *limit;
689 struct proc *p = curproc;
690 struct process *pr = p->p_p;
691
692 /*
693 * This thread might not observe the latest value of ps_limit
694 * if another thread updated the limits very recently on another CPU.
695 * However, the anomaly should disappear quickly, especially if
696 * there is any synchronization activity between the threads (or
697 * the CPUs).
698 */
699
700 limit = p->p_limit;
701 if (limit != pr->ps_limit) {
702 mtx_enter(&pr->ps_mtx);
703 limit = pr->ps_limit;
704 refcnt_take(&limit->pl_refcnt);
705 mtx_leave(&pr->ps_mtx);
706 if (p->p_limit != NULL)
707 lim_free(p->p_limit);
708 p->p_limit = limit;
709 }
710 KASSERT(limit != NULL);
711 return (limit);
712 }
713
714 /*
715 * Get the value of the resource limit in given process.
716 */
717 rlim_t
lim_cur_proc(struct proc * p,int which)718 lim_cur_proc(struct proc *p, int which)
719 {
720 struct process *pr = p->p_p;
721 rlim_t val;
722
723 KASSERT(which >= 0 && which < RLIM_NLIMITS);
724
725 mtx_enter(&pr->ps_mtx);
726 val = pr->ps_limit->pl_rlimit[which].rlim_cur;
727 mtx_leave(&pr->ps_mtx);
728 return (val);
729 }
730