xref: /netbsd-src/sys/kern/kern_resource.c (revision f3cfa6f6ce31685c6c4a758bc430e69eb99f50a4)
1 /*	$NetBSD: kern_resource.c,v 1.182 2019/04/05 00:33:21 mlelstv Exp $	*/
2 
3 /*-
4  * Copyright (c) 1982, 1986, 1991, 1993
5  *	The Regents of the University of California.  All rights reserved.
6  * (c) UNIX System Laboratories, Inc.
7  * All or some portions of this file are derived from material licensed
8  * to the University of California by American Telephone and Telegraph
9  * Co. or Unix System Laboratories, Inc. and are reproduced herein with
10  * the permission of UNIX System Laboratories, Inc.
11  *
12  * Redistribution and use in source and binary forms, with or without
13  * modification, are permitted provided that the following conditions
14  * are met:
15  * 1. Redistributions of source code must retain the above copyright
16  *    notice, this list of conditions and the following disclaimer.
17  * 2. Redistributions in binary form must reproduce the above copyright
18  *    notice, this list of conditions and the following disclaimer in the
19  *    documentation and/or other materials provided with the distribution.
20  * 3. Neither the name of the University nor the names of its contributors
21  *    may be used to endorse or promote products derived from this software
22  *    without specific prior written permission.
23  *
24  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
25  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
26  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
27  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
28  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
29  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
30  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
31  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
32  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
33  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
34  * SUCH DAMAGE.
35  *
36  *	@(#)kern_resource.c	8.8 (Berkeley) 2/14/95
37  */
38 
39 #include <sys/cdefs.h>
40 __KERNEL_RCSID(0, "$NetBSD: kern_resource.c,v 1.182 2019/04/05 00:33:21 mlelstv Exp $");
41 
42 #include <sys/param.h>
43 #include <sys/systm.h>
44 #include <sys/kernel.h>
45 #include <sys/file.h>
46 #include <sys/resourcevar.h>
47 #include <sys/kmem.h>
48 #include <sys/namei.h>
49 #include <sys/pool.h>
50 #include <sys/proc.h>
51 #include <sys/sysctl.h>
52 #include <sys/timevar.h>
53 #include <sys/kauth.h>
54 #include <sys/atomic.h>
55 #include <sys/mount.h>
56 #include <sys/syscallargs.h>
57 #include <sys/atomic.h>
58 
59 #include <uvm/uvm_extern.h>
60 
61 /*
62  * Maximum process data and stack limits.
63  * They are variables so they are patchable.
64  */
65 rlim_t			maxdmap = MAXDSIZ;
66 rlim_t			maxsmap = MAXSSIZ;
67 
68 static pool_cache_t	plimit_cache	__read_mostly;
69 static pool_cache_t	pstats_cache	__read_mostly;
70 
71 static kauth_listener_t	resource_listener;
72 static struct sysctllog	*proc_sysctllog;
73 
74 static int	donice(struct lwp *, struct proc *, int);
75 static void	sysctl_proc_setup(void);
76 
77 static int
78 resource_listener_cb(kauth_cred_t cred, kauth_action_t action, void *cookie,
79     void *arg0, void *arg1, void *arg2, void *arg3)
80 {
81 	struct proc *p;
82 	int result;
83 
84 	result = KAUTH_RESULT_DEFER;
85 	p = arg0;
86 
87 	switch (action) {
88 	case KAUTH_PROCESS_NICE:
89 		if (kauth_cred_geteuid(cred) != kauth_cred_geteuid(p->p_cred) &&
90 		    kauth_cred_getuid(cred) != kauth_cred_geteuid(p->p_cred)) {
91 			break;
92 		}
93 
94 		if ((u_long)arg1 >= p->p_nice)
95 			result = KAUTH_RESULT_ALLOW;
96 
97 		break;
98 
99 	case KAUTH_PROCESS_RLIMIT: {
100 		enum kauth_process_req req;
101 
102 		req = (enum kauth_process_req)(unsigned long)arg1;
103 
104 		switch (req) {
105 		case KAUTH_REQ_PROCESS_RLIMIT_GET:
106 			result = KAUTH_RESULT_ALLOW;
107 			break;
108 
109 		case KAUTH_REQ_PROCESS_RLIMIT_SET: {
110 			struct rlimit *new_rlimit;
111 			u_long which;
112 
113 			if ((p != curlwp->l_proc) &&
114 			    (proc_uidmatch(cred, p->p_cred) != 0))
115 				break;
116 
117 			new_rlimit = arg2;
118 			which = (u_long)arg3;
119 
120 			if (new_rlimit->rlim_max <= p->p_rlimit[which].rlim_max)
121 				result = KAUTH_RESULT_ALLOW;
122 
123 			break;
124 			}
125 
126 		default:
127 			break;
128 		}
129 
130 		break;
131 	}
132 
133 	default:
134 		break;
135 	}
136 
137 	return result;
138 }
139 
140 void
141 resource_init(void)
142 {
143 
144 	plimit_cache = pool_cache_init(sizeof(struct plimit), 0, 0, 0,
145 	    "plimitpl", NULL, IPL_NONE, NULL, NULL, NULL);
146 	pstats_cache = pool_cache_init(sizeof(struct pstats), 0, 0, 0,
147 	    "pstatspl", NULL, IPL_NONE, NULL, NULL, NULL);
148 
149 	resource_listener = kauth_listen_scope(KAUTH_SCOPE_PROCESS,
150 	    resource_listener_cb, NULL);
151 
152 	sysctl_proc_setup();
153 }
154 
155 /*
156  * Resource controls and accounting.
157  */
158 
159 int
160 sys_getpriority(struct lwp *l, const struct sys_getpriority_args *uap,
161     register_t *retval)
162 {
163 	/* {
164 		syscallarg(int) which;
165 		syscallarg(id_t) who;
166 	} */
167 	struct proc *curp = l->l_proc, *p;
168 	id_t who = SCARG(uap, who);
169 	int low = NZERO + PRIO_MAX + 1;
170 
171 	mutex_enter(proc_lock);
172 	switch (SCARG(uap, which)) {
173 	case PRIO_PROCESS:
174 		p = who ? proc_find(who) : curp;
175 		if (p != NULL)
176 			low = p->p_nice;
177 		break;
178 
179 	case PRIO_PGRP: {
180 		struct pgrp *pg;
181 
182 		if (who == 0)
183 			pg = curp->p_pgrp;
184 		else if ((pg = pgrp_find(who)) == NULL)
185 			break;
186 		LIST_FOREACH(p, &pg->pg_members, p_pglist) {
187 			if (p->p_nice < low)
188 				low = p->p_nice;
189 		}
190 		break;
191 	}
192 
193 	case PRIO_USER:
194 		if (who == 0)
195 			who = (int)kauth_cred_geteuid(l->l_cred);
196 		PROCLIST_FOREACH(p, &allproc) {
197 			mutex_enter(p->p_lock);
198 			if (kauth_cred_geteuid(p->p_cred) ==
199 			    (uid_t)who && p->p_nice < low)
200 				low = p->p_nice;
201 			mutex_exit(p->p_lock);
202 		}
203 		break;
204 
205 	default:
206 		mutex_exit(proc_lock);
207 		return EINVAL;
208 	}
209 	mutex_exit(proc_lock);
210 
211 	if (low == NZERO + PRIO_MAX + 1) {
212 		return ESRCH;
213 	}
214 	*retval = low - NZERO;
215 	return 0;
216 }
217 
218 int
219 sys_setpriority(struct lwp *l, const struct sys_setpriority_args *uap,
220     register_t *retval)
221 {
222 	/* {
223 		syscallarg(int) which;
224 		syscallarg(id_t) who;
225 		syscallarg(int) prio;
226 	} */
227 	struct proc *curp = l->l_proc, *p;
228 	id_t who = SCARG(uap, who);
229 	int found = 0, error = 0;
230 
231 	mutex_enter(proc_lock);
232 	switch (SCARG(uap, which)) {
233 	case PRIO_PROCESS:
234 		p = who ? proc_find(who) : curp;
235 		if (p != NULL) {
236 			mutex_enter(p->p_lock);
237 			found++;
238 			error = donice(l, p, SCARG(uap, prio));
239 			mutex_exit(p->p_lock);
240 		}
241 		break;
242 
243 	case PRIO_PGRP: {
244 		struct pgrp *pg;
245 
246 		if (who == 0)
247 			pg = curp->p_pgrp;
248 		else if ((pg = pgrp_find(who)) == NULL)
249 			break;
250 		LIST_FOREACH(p, &pg->pg_members, p_pglist) {
251 			mutex_enter(p->p_lock);
252 			found++;
253 			error = donice(l, p, SCARG(uap, prio));
254 			mutex_exit(p->p_lock);
255 			if (error)
256 				break;
257 		}
258 		break;
259 	}
260 
261 	case PRIO_USER:
262 		if (who == 0)
263 			who = (int)kauth_cred_geteuid(l->l_cred);
264 		PROCLIST_FOREACH(p, &allproc) {
265 			mutex_enter(p->p_lock);
266 			if (kauth_cred_geteuid(p->p_cred) ==
267 			    (uid_t)SCARG(uap, who)) {
268 				found++;
269 				error = donice(l, p, SCARG(uap, prio));
270 			}
271 			mutex_exit(p->p_lock);
272 			if (error)
273 				break;
274 		}
275 		break;
276 
277 	default:
278 		mutex_exit(proc_lock);
279 		return EINVAL;
280 	}
281 	mutex_exit(proc_lock);
282 
283 	return (found == 0) ? ESRCH : error;
284 }
285 
286 /*
287  * Renice a process.
288  *
289  * Call with the target process' credentials locked.
290  */
291 static int
292 donice(struct lwp *l, struct proc *chgp, int n)
293 {
294 	kauth_cred_t cred = l->l_cred;
295 
296 	KASSERT(mutex_owned(chgp->p_lock));
297 
298 	if (kauth_cred_geteuid(cred) && kauth_cred_getuid(cred) &&
299 	    kauth_cred_geteuid(cred) != kauth_cred_geteuid(chgp->p_cred) &&
300 	    kauth_cred_getuid(cred) != kauth_cred_geteuid(chgp->p_cred))
301 		return EPERM;
302 
303 	if (n > PRIO_MAX) {
304 		n = PRIO_MAX;
305 	}
306 	if (n < PRIO_MIN) {
307 		n = PRIO_MIN;
308 	}
309 	n += NZERO;
310 
311 	if (kauth_authorize_process(cred, KAUTH_PROCESS_NICE, chgp,
312 	    KAUTH_ARG(n), NULL, NULL)) {
313 		return EACCES;
314 	}
315 
316 	sched_nice(chgp, n);
317 	return 0;
318 }
319 
320 int
321 sys_setrlimit(struct lwp *l, const struct sys_setrlimit_args *uap,
322     register_t *retval)
323 {
324 	/* {
325 		syscallarg(int) which;
326 		syscallarg(const struct rlimit *) rlp;
327 	} */
328 	int error, which = SCARG(uap, which);
329 	struct rlimit alim;
330 
331 	error = copyin(SCARG(uap, rlp), &alim, sizeof(struct rlimit));
332 	if (error) {
333 		return error;
334 	}
335 	return dosetrlimit(l, l->l_proc, which, &alim);
336 }
337 
338 int
339 dosetrlimit(struct lwp *l, struct proc *p, int which, struct rlimit *limp)
340 {
341 	struct rlimit *alimp;
342 	int error;
343 
344 	if ((u_int)which >= RLIM_NLIMITS)
345 		return EINVAL;
346 
347 	if (limp->rlim_cur > limp->rlim_max) {
348 		/*
349 		 * This is programming error. According to SUSv2, we should
350 		 * return error in this case.
351 		 */
352 		return EINVAL;
353 	}
354 
355 	alimp = &p->p_rlimit[which];
356 	/* if we don't change the value, no need to limcopy() */
357 	if (limp->rlim_cur == alimp->rlim_cur &&
358 	    limp->rlim_max == alimp->rlim_max)
359 		return 0;
360 
361 	error = kauth_authorize_process(l->l_cred, KAUTH_PROCESS_RLIMIT,
362 	    p, KAUTH_ARG(KAUTH_REQ_PROCESS_RLIMIT_SET), limp, KAUTH_ARG(which));
363 	if (error)
364 		return error;
365 
366 	lim_privatise(p);
367 	/* p->p_limit is now unchangeable */
368 	alimp = &p->p_rlimit[which];
369 
370 	switch (which) {
371 
372 	case RLIMIT_DATA:
373 		if (limp->rlim_cur > maxdmap)
374 			limp->rlim_cur = maxdmap;
375 		if (limp->rlim_max > maxdmap)
376 			limp->rlim_max = maxdmap;
377 		break;
378 
379 	case RLIMIT_STACK:
380 		if (limp->rlim_cur > maxsmap)
381 			limp->rlim_cur = maxsmap;
382 		if (limp->rlim_max > maxsmap)
383 			limp->rlim_max = maxsmap;
384 
385 		/*
386 		 * Return EINVAL if the new stack size limit is lower than
387 		 * current usage. Otherwise, the process would get SIGSEGV the
388 		 * moment it would try to access anything on its current stack.
389 		 * This conforms to SUSv2.
390 		 */
391 		if (btoc(limp->rlim_cur) < p->p_vmspace->vm_ssize ||
392 		    btoc(limp->rlim_max) < p->p_vmspace->vm_ssize) {
393 			return EINVAL;
394 		}
395 
396 		/*
397 		 * Stack is allocated to the max at exec time with
398 		 * only "rlim_cur" bytes accessible (In other words,
399 		 * allocates stack dividing two contiguous regions at
400 		 * "rlim_cur" bytes boundary).
401 		 *
402 		 * Since allocation is done in terms of page, roundup
403 		 * "rlim_cur" (otherwise, contiguous regions
404 		 * overlap).  If stack limit is going up make more
405 		 * accessible, if going down make inaccessible.
406 		 */
407 		limp->rlim_max = round_page(limp->rlim_max);
408 		limp->rlim_cur = round_page(limp->rlim_cur);
409 		if (limp->rlim_cur != alimp->rlim_cur) {
410 			vaddr_t addr;
411 			vsize_t size;
412 			vm_prot_t prot;
413 			char *base, *tmp;
414 
415 			base = p->p_vmspace->vm_minsaddr;
416 			if (limp->rlim_cur > alimp->rlim_cur) {
417 				prot = VM_PROT_READ | VM_PROT_WRITE;
418 				size = limp->rlim_cur - alimp->rlim_cur;
419 				tmp = STACK_GROW(base, alimp->rlim_cur);
420 			} else {
421 				prot = VM_PROT_NONE;
422 				size = alimp->rlim_cur - limp->rlim_cur;
423 				tmp = STACK_GROW(base, limp->rlim_cur);
424 			}
425 			addr = (vaddr_t)STACK_ALLOC(tmp, size);
426 			(void) uvm_map_protect(&p->p_vmspace->vm_map,
427 			    addr, addr + size, prot, false);
428 		}
429 		break;
430 
431 	case RLIMIT_NOFILE:
432 		if (limp->rlim_cur > maxfiles)
433 			limp->rlim_cur = maxfiles;
434 		if (limp->rlim_max > maxfiles)
435 			limp->rlim_max = maxfiles;
436 		break;
437 
438 	case RLIMIT_NPROC:
439 		if (limp->rlim_cur > maxproc)
440 			limp->rlim_cur = maxproc;
441 		if (limp->rlim_max > maxproc)
442 			limp->rlim_max = maxproc;
443 		break;
444 
445 	case RLIMIT_NTHR:
446 		if (limp->rlim_cur > maxlwp)
447 			limp->rlim_cur = maxlwp;
448 		if (limp->rlim_max > maxlwp)
449 			limp->rlim_max = maxlwp;
450 		break;
451 	}
452 
453 	mutex_enter(&p->p_limit->pl_lock);
454 	*alimp = *limp;
455 	mutex_exit(&p->p_limit->pl_lock);
456 	return 0;
457 }
458 
459 int
460 sys_getrlimit(struct lwp *l, const struct sys_getrlimit_args *uap,
461     register_t *retval)
462 {
463 	/* {
464 		syscallarg(int) which;
465 		syscallarg(struct rlimit *) rlp;
466 	} */
467 	struct proc *p = l->l_proc;
468 	int which = SCARG(uap, which);
469 	struct rlimit rl;
470 
471 	if ((u_int)which >= RLIM_NLIMITS)
472 		return EINVAL;
473 
474 	mutex_enter(p->p_lock);
475 	memcpy(&rl, &p->p_rlimit[which], sizeof(rl));
476 	mutex_exit(p->p_lock);
477 
478 	return copyout(&rl, SCARG(uap, rlp), sizeof(rl));
479 }
480 
481 /*
482  * Transform the running time and tick information in proc p into user,
483  * system, and interrupt time usage.
484  *
485  * Should be called with p->p_lock held unless called from exit1().
486  */
487 void
488 calcru(struct proc *p, struct timeval *up, struct timeval *sp,
489     struct timeval *ip, struct timeval *rp)
490 {
491 	uint64_t u, st, ut, it, tot, dt;
492 	struct lwp *l;
493 	struct bintime tm;
494 	struct timeval tv;
495 
496 	KASSERT(p->p_stat == SDEAD || mutex_owned(p->p_lock));
497 
498 	mutex_spin_enter(&p->p_stmutex);
499 	st = p->p_sticks;
500 	ut = p->p_uticks;
501 	it = p->p_iticks;
502 	mutex_spin_exit(&p->p_stmutex);
503 
504 	tm = p->p_rtime;
505 
506 	LIST_FOREACH(l, &p->p_lwps, l_sibling) {
507 		lwp_lock(l);
508 		bintime_add(&tm, &l->l_rtime);
509 		if ((l->l_pflag & LP_RUNNING) != 0) {
510 			struct bintime diff;
511 			/*
512 			 * Adjust for the current time slice.  This is
513 			 * actually fairly important since the error
514 			 * here is on the order of a time quantum,
515 			 * which is much greater than the sampling
516 			 * error.
517 			 */
518 			binuptime(&diff);
519 			bintime_sub(&diff, &l->l_stime);
520 			bintime_add(&tm, &diff);
521 		}
522 		lwp_unlock(l);
523 	}
524 
525 	tot = st + ut + it;
526 	bintime2timeval(&tm, &tv);
527 	u = (uint64_t)tv.tv_sec * 1000000ul + tv.tv_usec;
528 
529 	if (tot == 0) {
530 		/* No ticks, so can't use to share time out, split 50-50 */
531 		st = ut = u / 2;
532 	} else {
533 		st = (u * st) / tot;
534 		ut = (u * ut) / tot;
535 	}
536 
537 	/*
538 	 * Try to avoid lying to the users (too much)
539 	 *
540 	 * Of course, user/sys time are based on sampling (ie: statistics)
541 	 * so that would be impossible, but convincing the mark
542 	 * that we have used less ?time this call than we had
543 	 * last time, is beyond reasonable...  (the con fails!)
544 	 *
545 	 * Note that since actual used time cannot decrease, either
546 	 * utime or stime (or both) must be greater now than last time
547 	 * (or both the same) - if one seems to have decreased, hold
548 	 * it constant and steal the necessary bump from the other
549 	 * which must have increased.
550 	 */
551 	if (p->p_xutime > ut) {
552 		dt = p->p_xutime - ut;
553 		st -= uimin(dt, st);
554 		ut = p->p_xutime;
555 	} else if (p->p_xstime > st) {
556 		dt = p->p_xstime - st;
557 		ut -= uimin(dt, ut);
558 		st = p->p_xstime;
559 	}
560 
561 	if (sp != NULL) {
562 		p->p_xstime = st;
563 		sp->tv_sec = st / 1000000;
564 		sp->tv_usec = st % 1000000;
565 	}
566 	if (up != NULL) {
567 		p->p_xutime = ut;
568 		up->tv_sec = ut / 1000000;
569 		up->tv_usec = ut % 1000000;
570 	}
571 	if (ip != NULL) {
572 		if (it != 0)		/* it != 0 --> tot != 0 */
573 			it = (u * it) / tot;
574 		ip->tv_sec = it / 1000000;
575 		ip->tv_usec = it % 1000000;
576 	}
577 	if (rp != NULL) {
578 		*rp = tv;
579 	}
580 }
581 
582 int
583 sys___getrusage50(struct lwp *l, const struct sys___getrusage50_args *uap,
584     register_t *retval)
585 {
586 	/* {
587 		syscallarg(int) who;
588 		syscallarg(struct rusage *) rusage;
589 	} */
590 	int error;
591 	struct rusage ru;
592 	struct proc *p = l->l_proc;
593 
594 	error = getrusage1(p, SCARG(uap, who), &ru);
595 	if (error != 0)
596 		return error;
597 
598 	return copyout(&ru, SCARG(uap, rusage), sizeof(ru));
599 }
600 
601 int
602 getrusage1(struct proc *p, int who, struct rusage *ru) {
603 
604 	switch (who) {
605 	case RUSAGE_SELF:
606 		mutex_enter(p->p_lock);
607 		ruspace(p);
608 		memcpy(ru, &p->p_stats->p_ru, sizeof(*ru));
609 		calcru(p, &ru->ru_utime, &ru->ru_stime, NULL, NULL);
610 		rulwps(p, ru);
611 		mutex_exit(p->p_lock);
612 		break;
613 	case RUSAGE_CHILDREN:
614 		mutex_enter(p->p_lock);
615 		memcpy(ru, &p->p_stats->p_cru, sizeof(*ru));
616 		mutex_exit(p->p_lock);
617 		break;
618 	default:
619 		return EINVAL;
620 	}
621 
622 	return 0;
623 }
624 
625 void
626 ruspace(struct proc *p)
627 {
628 	struct vmspace *vm = p->p_vmspace;
629 	struct rusage *ru = &p->p_stats->p_ru;
630 
631 	ru->ru_ixrss = vm->vm_tsize << (PAGE_SHIFT - 10);
632 	ru->ru_idrss = vm->vm_dsize << (PAGE_SHIFT - 10);
633 	ru->ru_isrss = vm->vm_ssize << (PAGE_SHIFT - 10);
634 #ifdef __HAVE_NO_PMAP_STATS
635 	/* We don't keep track of the max so we get the current */
636 	ru->ru_maxrss = vm_resident_count(vm) << (PAGE_SHIFT - 10);
637 #else
638 	ru->ru_maxrss = vm->vm_rssmax << (PAGE_SHIFT - 10);
639 #endif
640 }
641 
642 void
643 ruadd(struct rusage *ru, struct rusage *ru2)
644 {
645 	long *ip, *ip2;
646 	int i;
647 
648 	timeradd(&ru->ru_utime, &ru2->ru_utime, &ru->ru_utime);
649 	timeradd(&ru->ru_stime, &ru2->ru_stime, &ru->ru_stime);
650 	if (ru->ru_maxrss < ru2->ru_maxrss)
651 		ru->ru_maxrss = ru2->ru_maxrss;
652 	ip = &ru->ru_first; ip2 = &ru2->ru_first;
653 	for (i = &ru->ru_last - &ru->ru_first; i >= 0; i--)
654 		*ip++ += *ip2++;
655 }
656 
657 void
658 rulwps(proc_t *p, struct rusage *ru)
659 {
660 	lwp_t *l;
661 
662 	KASSERT(mutex_owned(p->p_lock));
663 
664 	LIST_FOREACH(l, &p->p_lwps, l_sibling) {
665 		ruadd(ru, &l->l_ru);
666 		ru->ru_nvcsw += (l->l_ncsw - l->l_nivcsw);
667 		ru->ru_nivcsw += l->l_nivcsw;
668 	}
669 }
670 
671 /*
672  * lim_copy: make a copy of the plimit structure.
673  *
674  * We use copy-on-write after fork, and copy when a limit is changed.
675  */
676 struct plimit *
677 lim_copy(struct plimit *lim)
678 {
679 	struct plimit *newlim;
680 	char *corename;
681 	size_t alen, len;
682 
683 	newlim = pool_cache_get(plimit_cache, PR_WAITOK);
684 	mutex_init(&newlim->pl_lock, MUTEX_DEFAULT, IPL_NONE);
685 	newlim->pl_writeable = false;
686 	newlim->pl_refcnt = 1;
687 	newlim->pl_sv_limit = NULL;
688 
689 	mutex_enter(&lim->pl_lock);
690 	memcpy(newlim->pl_rlimit, lim->pl_rlimit,
691 	    sizeof(struct rlimit) * RLIM_NLIMITS);
692 
693 	/*
694 	 * Note: the common case is a use of default core name.
695 	 */
696 	alen = 0;
697 	corename = NULL;
698 	for (;;) {
699 		if (lim->pl_corename == defcorename) {
700 			newlim->pl_corename = defcorename;
701 			newlim->pl_cnlen = 0;
702 			break;
703 		}
704 		len = lim->pl_cnlen;
705 		if (len == alen) {
706 			newlim->pl_corename = corename;
707 			newlim->pl_cnlen = len;
708 			memcpy(corename, lim->pl_corename, len);
709 			corename = NULL;
710 			break;
711 		}
712 		mutex_exit(&lim->pl_lock);
713 		if (corename) {
714 			kmem_free(corename, alen);
715 		}
716 		alen = len;
717 		corename = kmem_alloc(alen, KM_SLEEP);
718 		mutex_enter(&lim->pl_lock);
719 	}
720 	mutex_exit(&lim->pl_lock);
721 
722 	if (corename) {
723 		kmem_free(corename, alen);
724 	}
725 	return newlim;
726 }
727 
728 void
729 lim_addref(struct plimit *lim)
730 {
731 	atomic_inc_uint(&lim->pl_refcnt);
732 }
733 
734 /*
735  * lim_privatise: give a process its own private plimit structure.
736  */
737 void
738 lim_privatise(proc_t *p)
739 {
740 	struct plimit *lim = p->p_limit, *newlim;
741 
742 	if (lim->pl_writeable) {
743 		return;
744 	}
745 
746 	newlim = lim_copy(lim);
747 
748 	mutex_enter(p->p_lock);
749 	if (p->p_limit->pl_writeable) {
750 		/* Other thread won the race. */
751 		mutex_exit(p->p_lock);
752 		lim_free(newlim);
753 		return;
754 	}
755 
756 	/*
757 	 * Since p->p_limit can be accessed without locked held,
758 	 * old limit structure must not be deleted yet.
759 	 */
760 	newlim->pl_sv_limit = p->p_limit;
761 	newlim->pl_writeable = true;
762 	p->p_limit = newlim;
763 	mutex_exit(p->p_lock);
764 }
765 
766 void
767 lim_setcorename(proc_t *p, char *name, size_t len)
768 {
769 	struct plimit *lim;
770 	char *oname;
771 	size_t olen;
772 
773 	lim_privatise(p);
774 	lim = p->p_limit;
775 
776 	mutex_enter(&lim->pl_lock);
777 	oname = lim->pl_corename;
778 	olen = lim->pl_cnlen;
779 	lim->pl_corename = name;
780 	lim->pl_cnlen = len;
781 	mutex_exit(&lim->pl_lock);
782 
783 	if (oname != defcorename) {
784 		kmem_free(oname, olen);
785 	}
786 }
787 
788 void
789 lim_free(struct plimit *lim)
790 {
791 	struct plimit *sv_lim;
792 
793 	do {
794 		if (atomic_dec_uint_nv(&lim->pl_refcnt) > 0) {
795 			return;
796 		}
797 		if (lim->pl_corename != defcorename) {
798 			kmem_free(lim->pl_corename, lim->pl_cnlen);
799 		}
800 		sv_lim = lim->pl_sv_limit;
801 		mutex_destroy(&lim->pl_lock);
802 		pool_cache_put(plimit_cache, lim);
803 	} while ((lim = sv_lim) != NULL);
804 }
805 
806 struct pstats *
807 pstatscopy(struct pstats *ps)
808 {
809 	struct pstats *nps;
810 	size_t len;
811 
812 	nps = pool_cache_get(pstats_cache, PR_WAITOK);
813 
814 	len = (char *)&nps->pstat_endzero - (char *)&nps->pstat_startzero;
815 	memset(&nps->pstat_startzero, 0, len);
816 
817 	len = (char *)&nps->pstat_endcopy - (char *)&nps->pstat_startcopy;
818 	memcpy(&nps->pstat_startcopy, &ps->pstat_startcopy, len);
819 
820 	return nps;
821 }
822 
823 void
824 pstatsfree(struct pstats *ps)
825 {
826 
827 	pool_cache_put(pstats_cache, ps);
828 }
829 
830 /*
831  * sysctl_proc_findproc: a routine for sysctl proc subtree helpers that
832  * need to pick a valid process by PID.
833  *
834  * => Hold a reference on the process, on success.
835  */
836 static int
837 sysctl_proc_findproc(lwp_t *l, pid_t pid, proc_t **p2)
838 {
839 	proc_t *p;
840 	int error;
841 
842 	if (pid == PROC_CURPROC) {
843 		p = l->l_proc;
844 	} else {
845 		mutex_enter(proc_lock);
846 		p = proc_find(pid);
847 		if (p == NULL) {
848 			mutex_exit(proc_lock);
849 			return ESRCH;
850 		}
851 	}
852 	error = rw_tryenter(&p->p_reflock, RW_READER) ? 0 : EBUSY;
853 	if (pid != PROC_CURPROC) {
854 		mutex_exit(proc_lock);
855 	}
856 	*p2 = p;
857 	return error;
858 }
859 
860 /*
861  * sysctl_proc_paxflags: helper routine to get process's paxctl flags
862  */
863 static int
864 sysctl_proc_paxflags(SYSCTLFN_ARGS)
865 {
866 	struct proc *p;
867 	struct sysctlnode node;
868 	int paxflags;
869 	int error;
870 
871 	/* First, validate the request. */
872 	if (namelen != 0 || name[-1] != PROC_PID_PAXFLAGS)
873 		return EINVAL;
874 
875 	/* Find the process.  Hold a reference (p_reflock), if found. */
876 	error = sysctl_proc_findproc(l, (pid_t)name[-2], &p);
877 	if (error)
878 		return error;
879 
880 	/* XXX-elad */
881 	error = kauth_authorize_process(l->l_cred, KAUTH_PROCESS_CANSEE, p,
882 	    KAUTH_ARG(KAUTH_REQ_PROCESS_CANSEE_ENTRY), NULL, NULL);
883 	if (error) {
884 		rw_exit(&p->p_reflock);
885 		return error;
886 	}
887 
888 	/* Retrieve the limits. */
889 	node = *rnode;
890 	paxflags = p->p_pax;
891 	node.sysctl_data = &paxflags;
892 
893 	error = sysctl_lookup(SYSCTLFN_CALL(&node));
894 
895 	/* If attempting to write new value, it's an error */
896 	if (error == 0 && newp != NULL)
897 		error = EACCES;
898 
899 	rw_exit(&p->p_reflock);
900 	return error;
901 }
902 
903 /*
904  * sysctl_proc_corename: helper routine to get or set the core file name
905  * for a process specified by PID.
906  */
907 static int
908 sysctl_proc_corename(SYSCTLFN_ARGS)
909 {
910 	struct proc *p;
911 	struct plimit *lim;
912 	char *cnbuf, *cname;
913 	struct sysctlnode node;
914 	size_t len;
915 	int error;
916 
917 	/* First, validate the request. */
918 	if (namelen != 0 || name[-1] != PROC_PID_CORENAME)
919 		return EINVAL;
920 
921 	/* Find the process.  Hold a reference (p_reflock), if found. */
922 	error = sysctl_proc_findproc(l, (pid_t)name[-2], &p);
923 	if (error)
924 		return error;
925 
926 	/* XXX-elad */
927 	error = kauth_authorize_process(l->l_cred, KAUTH_PROCESS_CANSEE, p,
928 	    KAUTH_ARG(KAUTH_REQ_PROCESS_CANSEE_ENTRY), NULL, NULL);
929 	if (error) {
930 		rw_exit(&p->p_reflock);
931 		return error;
932 	}
933 
934 	cnbuf = PNBUF_GET();
935 
936 	if (oldp) {
937 		/* Get case: copy the core name into the buffer. */
938 		error = kauth_authorize_process(l->l_cred,
939 		    KAUTH_PROCESS_CORENAME, p,
940 		    KAUTH_ARG(KAUTH_REQ_PROCESS_CORENAME_GET), NULL, NULL);
941 		if (error) {
942 			goto done;
943 		}
944 		lim = p->p_limit;
945 		mutex_enter(&lim->pl_lock);
946 		strlcpy(cnbuf, lim->pl_corename, MAXPATHLEN);
947 		mutex_exit(&lim->pl_lock);
948 	}
949 
950 	node = *rnode;
951 	node.sysctl_data = cnbuf;
952 	error = sysctl_lookup(SYSCTLFN_CALL(&node));
953 
954 	/* Return if error, or if caller is only getting the core name. */
955 	if (error || newp == NULL) {
956 		goto done;
957 	}
958 
959 	/*
960 	 * Set case.  Check permission and then validate new core name.
961 	 * It must be either "core", "/core", or end in ".core".
962 	 */
963 	error = kauth_authorize_process(l->l_cred, KAUTH_PROCESS_CORENAME,
964 	    p, KAUTH_ARG(KAUTH_REQ_PROCESS_CORENAME_SET), cnbuf, NULL);
965 	if (error) {
966 		goto done;
967 	}
968 	len = strlen(cnbuf);
969 	if ((len < 4 || strcmp(cnbuf + len - 4, "core") != 0) ||
970 	    (len > 4 && cnbuf[len - 5] != '/' && cnbuf[len - 5] != '.')) {
971 		error = EINVAL;
972 		goto done;
973 	}
974 
975 	/* Allocate, copy and set the new core name for plimit structure. */
976 	cname = kmem_alloc(++len, KM_NOSLEEP);
977 	if (cname == NULL) {
978 		error = ENOMEM;
979 		goto done;
980 	}
981 	memcpy(cname, cnbuf, len);
982 	lim_setcorename(p, cname, len);
983 done:
984 	rw_exit(&p->p_reflock);
985 	PNBUF_PUT(cnbuf);
986 	return error;
987 }
988 
989 /*
990  * sysctl_proc_stop: helper routine for checking/setting the stop flags.
991  */
992 static int
993 sysctl_proc_stop(SYSCTLFN_ARGS)
994 {
995 	struct proc *p;
996 	int isset, flag, error = 0;
997 	struct sysctlnode node;
998 
999 	if (namelen != 0)
1000 		return EINVAL;
1001 
1002 	/* Find the process.  Hold a reference (p_reflock), if found. */
1003 	error = sysctl_proc_findproc(l, (pid_t)name[-2], &p);
1004 	if (error)
1005 		return error;
1006 
1007 	/* XXX-elad */
1008 	error = kauth_authorize_process(l->l_cred, KAUTH_PROCESS_CANSEE, p,
1009 	    KAUTH_ARG(KAUTH_REQ_PROCESS_CANSEE_ENTRY), NULL, NULL);
1010 	if (error) {
1011 		goto out;
1012 	}
1013 
1014 	/* Determine the flag. */
1015 	switch (rnode->sysctl_num) {
1016 	case PROC_PID_STOPFORK:
1017 		flag = PS_STOPFORK;
1018 		break;
1019 	case PROC_PID_STOPEXEC:
1020 		flag = PS_STOPEXEC;
1021 		break;
1022 	case PROC_PID_STOPEXIT:
1023 		flag = PS_STOPEXIT;
1024 		break;
1025 	default:
1026 		error = EINVAL;
1027 		goto out;
1028 	}
1029 	isset = (p->p_flag & flag) ? 1 : 0;
1030 	node = *rnode;
1031 	node.sysctl_data = &isset;
1032 	error = sysctl_lookup(SYSCTLFN_CALL(&node));
1033 
1034 	/* Return if error, or if callers is only getting the flag. */
1035 	if (error || newp == NULL) {
1036 		goto out;
1037 	}
1038 
1039 	/* Check if caller can set the flags. */
1040 	error = kauth_authorize_process(l->l_cred, KAUTH_PROCESS_STOPFLAG,
1041 	    p, KAUTH_ARG(flag), NULL, NULL);
1042 	if (error) {
1043 		goto out;
1044 	}
1045 	mutex_enter(p->p_lock);
1046 	if (isset) {
1047 		p->p_sflag |= flag;
1048 	} else {
1049 		p->p_sflag &= ~flag;
1050 	}
1051 	mutex_exit(p->p_lock);
1052 out:
1053 	rw_exit(&p->p_reflock);
1054 	return error;
1055 }
1056 
1057 /*
1058  * sysctl_proc_plimit: helper routine to get/set rlimits of a process.
1059  */
1060 static int
1061 sysctl_proc_plimit(SYSCTLFN_ARGS)
1062 {
1063 	struct proc *p;
1064 	u_int limitno;
1065 	int which, error = 0;
1066         struct rlimit alim;
1067 	struct sysctlnode node;
1068 
1069 	if (namelen != 0)
1070 		return EINVAL;
1071 
1072 	which = name[-1];
1073 	if (which != PROC_PID_LIMIT_TYPE_SOFT &&
1074 	    which != PROC_PID_LIMIT_TYPE_HARD)
1075 		return EINVAL;
1076 
1077 	limitno = name[-2] - 1;
1078 	if (limitno >= RLIM_NLIMITS)
1079 		return EINVAL;
1080 
1081 	if (name[-3] != PROC_PID_LIMIT)
1082 		return EINVAL;
1083 
1084 	/* Find the process.  Hold a reference (p_reflock), if found. */
1085 	error = sysctl_proc_findproc(l, (pid_t)name[-4], &p);
1086 	if (error)
1087 		return error;
1088 
1089 	/* XXX-elad */
1090 	error = kauth_authorize_process(l->l_cred, KAUTH_PROCESS_CANSEE, p,
1091 	    KAUTH_ARG(KAUTH_REQ_PROCESS_CANSEE_ENTRY), NULL, NULL);
1092 	if (error)
1093 		goto out;
1094 
1095 	/* Check if caller can retrieve the limits. */
1096 	if (newp == NULL) {
1097 		error = kauth_authorize_process(l->l_cred, KAUTH_PROCESS_RLIMIT,
1098 		    p, KAUTH_ARG(KAUTH_REQ_PROCESS_RLIMIT_GET), &alim,
1099 		    KAUTH_ARG(which));
1100 		if (error)
1101 			goto out;
1102 	}
1103 
1104 	/* Retrieve the limits. */
1105 	node = *rnode;
1106 	memcpy(&alim, &p->p_rlimit[limitno], sizeof(alim));
1107 	if (which == PROC_PID_LIMIT_TYPE_HARD) {
1108 		node.sysctl_data = &alim.rlim_max;
1109 	} else {
1110 		node.sysctl_data = &alim.rlim_cur;
1111 	}
1112 	error = sysctl_lookup(SYSCTLFN_CALL(&node));
1113 
1114 	/* Return if error, or if we are only retrieving the limits. */
1115 	if (error || newp == NULL) {
1116 		goto out;
1117 	}
1118 	error = dosetrlimit(l, p, limitno, &alim);
1119 out:
1120 	rw_exit(&p->p_reflock);
1121 	return error;
1122 }
1123 
1124 /*
1125  * Setup sysctl nodes.
1126  */
1127 static void
1128 sysctl_proc_setup(void)
1129 {
1130 
1131 	sysctl_createv(&proc_sysctllog, 0, NULL, NULL,
1132 		       CTLFLAG_PERMANENT|CTLFLAG_ANYNUMBER,
1133 		       CTLTYPE_NODE, "curproc",
1134 		       SYSCTL_DESCR("Per-process settings"),
1135 		       NULL, 0, NULL, 0,
1136 		       CTL_PROC, PROC_CURPROC, CTL_EOL);
1137 
1138 	sysctl_createv(&proc_sysctllog, 0, NULL, NULL,
1139 		       CTLFLAG_PERMANENT|CTLFLAG_READONLY,
1140 		       CTLTYPE_INT, "paxflags",
1141 		       SYSCTL_DESCR("Process PAX control flags"),
1142 		       sysctl_proc_paxflags, 0, NULL, 0,
1143 		       CTL_PROC, PROC_CURPROC, PROC_PID_PAXFLAGS, CTL_EOL);
1144 
1145 	sysctl_createv(&proc_sysctllog, 0, NULL, NULL,
1146 		       CTLFLAG_PERMANENT|CTLFLAG_READWRITE|CTLFLAG_ANYWRITE,
1147 		       CTLTYPE_STRING, "corename",
1148 		       SYSCTL_DESCR("Core file name"),
1149 		       sysctl_proc_corename, 0, NULL, MAXPATHLEN,
1150 		       CTL_PROC, PROC_CURPROC, PROC_PID_CORENAME, CTL_EOL);
1151 	sysctl_createv(&proc_sysctllog, 0, NULL, NULL,
1152 		       CTLFLAG_PERMANENT,
1153 		       CTLTYPE_NODE, "rlimit",
1154 		       SYSCTL_DESCR("Process limits"),
1155 		       NULL, 0, NULL, 0,
1156 		       CTL_PROC, PROC_CURPROC, PROC_PID_LIMIT, CTL_EOL);
1157 
1158 #define create_proc_plimit(s, n) do {					\
1159 	sysctl_createv(&proc_sysctllog, 0, NULL, NULL,			\
1160 		       CTLFLAG_PERMANENT,				\
1161 		       CTLTYPE_NODE, s,					\
1162 		       SYSCTL_DESCR("Process " s " limits"),		\
1163 		       NULL, 0, NULL, 0,				\
1164 		       CTL_PROC, PROC_CURPROC, PROC_PID_LIMIT, n,	\
1165 		       CTL_EOL);					\
1166 	sysctl_createv(&proc_sysctllog, 0, NULL, NULL,			\
1167 		       CTLFLAG_PERMANENT|CTLFLAG_READWRITE|CTLFLAG_ANYWRITE, \
1168 		       CTLTYPE_QUAD, "soft",				\
1169 		       SYSCTL_DESCR("Process soft " s " limit"),	\
1170 		       sysctl_proc_plimit, 0, NULL, 0,			\
1171 		       CTL_PROC, PROC_CURPROC, PROC_PID_LIMIT, n,	\
1172 		       PROC_PID_LIMIT_TYPE_SOFT, CTL_EOL);		\
1173 	sysctl_createv(&proc_sysctllog, 0, NULL, NULL,			\
1174 		       CTLFLAG_PERMANENT|CTLFLAG_READWRITE|CTLFLAG_ANYWRITE, \
1175 		       CTLTYPE_QUAD, "hard",				\
1176 		       SYSCTL_DESCR("Process hard " s " limit"),	\
1177 		       sysctl_proc_plimit, 0, NULL, 0,			\
1178 		       CTL_PROC, PROC_CURPROC, PROC_PID_LIMIT, n,	\
1179 		       PROC_PID_LIMIT_TYPE_HARD, CTL_EOL);		\
1180 	} while (0/*CONSTCOND*/)
1181 
1182 	create_proc_plimit("cputime",		PROC_PID_LIMIT_CPU);
1183 	create_proc_plimit("filesize",		PROC_PID_LIMIT_FSIZE);
1184 	create_proc_plimit("datasize",		PROC_PID_LIMIT_DATA);
1185 	create_proc_plimit("stacksize",		PROC_PID_LIMIT_STACK);
1186 	create_proc_plimit("coredumpsize",	PROC_PID_LIMIT_CORE);
1187 	create_proc_plimit("memoryuse",		PROC_PID_LIMIT_RSS);
1188 	create_proc_plimit("memorylocked",	PROC_PID_LIMIT_MEMLOCK);
1189 	create_proc_plimit("maxproc",		PROC_PID_LIMIT_NPROC);
1190 	create_proc_plimit("descriptors",	PROC_PID_LIMIT_NOFILE);
1191 	create_proc_plimit("sbsize",		PROC_PID_LIMIT_SBSIZE);
1192 	create_proc_plimit("vmemoryuse",	PROC_PID_LIMIT_AS);
1193 	create_proc_plimit("maxlwp",		PROC_PID_LIMIT_NTHR);
1194 
1195 #undef create_proc_plimit
1196 
1197 	sysctl_createv(&proc_sysctllog, 0, NULL, NULL,
1198 		       CTLFLAG_PERMANENT|CTLFLAG_READWRITE|CTLFLAG_ANYWRITE,
1199 		       CTLTYPE_INT, "stopfork",
1200 		       SYSCTL_DESCR("Stop process at fork(2)"),
1201 		       sysctl_proc_stop, 0, NULL, 0,
1202 		       CTL_PROC, PROC_CURPROC, PROC_PID_STOPFORK, CTL_EOL);
1203 	sysctl_createv(&proc_sysctllog, 0, NULL, NULL,
1204 		       CTLFLAG_PERMANENT|CTLFLAG_READWRITE|CTLFLAG_ANYWRITE,
1205 		       CTLTYPE_INT, "stopexec",
1206 		       SYSCTL_DESCR("Stop process at execve(2)"),
1207 		       sysctl_proc_stop, 0, NULL, 0,
1208 		       CTL_PROC, PROC_CURPROC, PROC_PID_STOPEXEC, CTL_EOL);
1209 	sysctl_createv(&proc_sysctllog, 0, NULL, NULL,
1210 		       CTLFLAG_PERMANENT|CTLFLAG_READWRITE|CTLFLAG_ANYWRITE,
1211 		       CTLTYPE_INT, "stopexit",
1212 		       SYSCTL_DESCR("Stop process before completing exit"),
1213 		       sysctl_proc_stop, 0, NULL, 0,
1214 		       CTL_PROC, PROC_CURPROC, PROC_PID_STOPEXIT, CTL_EOL);
1215 }
1216