xref: /freebsd/sys/net/pfil.c (revision 1edb7116f450c1a1793f2fd25f6bdc16735ef888)
1 /*	$NetBSD: pfil.c,v 1.20 2001/11/12 23:49:46 lukem Exp $	*/
2 
3 /*-
4  * SPDX-License-Identifier: BSD-3-Clause
5  *
6  * Copyright (c) 2019 Gleb Smirnoff <glebius@FreeBSD.org>
7  * Copyright (c) 1996 Matthew R. Green
8  * All rights reserved.
9  *
10  * Redistribution and use in source and binary forms, with or without
11  * modification, are permitted provided that the following conditions
12  * are met:
13  * 1. Redistributions of source code must retain the above copyright
14  *    notice, this list of conditions and the following disclaimer.
15  * 2. Redistributions in binary form must reproduce the above copyright
16  *    notice, this list of conditions and the following disclaimer in the
17  *    documentation and/or other materials provided with the distribution.
18  * 3. The name of the author may not be used to endorse or promote products
19  *    derived from this software without specific prior written permission.
20  *
21  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
22  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
23  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
24  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
25  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
26  * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
27  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
28  * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
29  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31  * SUCH DAMAGE.
32  */
33 
34 #include <sys/param.h>
35 #include <sys/conf.h>
36 #include <sys/kernel.h>
37 #include <sys/epoch.h>
38 #include <sys/errno.h>
39 #include <sys/lock.h>
40 #include <sys/malloc.h>
41 #include <sys/socket.h>
42 #include <sys/socketvar.h>
43 #include <sys/systm.h>
44 #include <sys/lock.h>
45 #include <sys/mutex.h>
46 #include <sys/proc.h>
47 #include <sys/queue.h>
48 #include <sys/ucred.h>
49 #include <sys/jail.h>
50 
51 #include <net/if.h>
52 #include <net/if_var.h>
53 #include <net/pfil.h>
54 
55 static MALLOC_DEFINE(M_PFIL, "pfil", "pfil(9) packet filter hooks");
56 
57 static int pfil_ioctl(struct cdev *, u_long, caddr_t, int, struct thread *);
58 static struct cdevsw pfil_cdevsw = {
59 	.d_ioctl =	pfil_ioctl,
60 	.d_name =	PFILDEV,
61 	.d_version =	D_VERSION,
62 };
63 static struct cdev *pfil_dev;
64 
65 static struct mtx pfil_lock;
66 MTX_SYSINIT(pfil_mtxinit, &pfil_lock, "pfil(9) lock", MTX_DEF);
67 #define	PFIL_LOCK()	mtx_lock(&pfil_lock)
68 #define	PFIL_UNLOCK()	mtx_unlock(&pfil_lock)
69 #define	PFIL_LOCK_ASSERT()	mtx_assert(&pfil_lock, MA_OWNED)
70 
71 struct pfil_hook {
72 	pfil_mbuf_chk_t	 hook_mbuf_chk;
73 	pfil_mem_chk_t	 hook_mem_chk;
74 	void		*hook_ruleset;
75 	int		 hook_flags;
76 	int		 hook_links;
77 	enum pfil_types	 hook_type;
78 	const char	*hook_modname;
79 	const char	*hook_rulname;
80 	LIST_ENTRY(pfil_hook) hook_list;
81 };
82 
83 struct pfil_link {
84 	CK_STAILQ_ENTRY(pfil_link) link_chain;
85 	pfil_mbuf_chk_t		 link_mbuf_chk;
86 	pfil_mem_chk_t		 link_mem_chk;
87 	void			*link_ruleset;
88 	int			 link_flags;
89 	struct pfil_hook	*link_hook;
90 	struct epoch_context	 link_epoch_ctx;
91 };
92 
93 typedef CK_STAILQ_HEAD(pfil_chain, pfil_link)	pfil_chain_t;
94 struct pfil_head {
95 	int		 head_nhooksin;
96 	int		 head_nhooksout;
97 	pfil_chain_t	 head_in;
98 	pfil_chain_t	 head_out;
99 	int		 head_flags;
100 	enum pfil_types	 head_type;
101 	LIST_ENTRY(pfil_head) head_list;
102 	const char	*head_name;
103 };
104 
105 LIST_HEAD(pfilheadhead, pfil_head);
106 VNET_DEFINE_STATIC(struct pfilheadhead, pfil_head_list) =
107     LIST_HEAD_INITIALIZER(pfil_head_list);
108 #define	V_pfil_head_list	VNET(pfil_head_list)
109 
110 LIST_HEAD(pfilhookhead, pfil_hook);
111 VNET_DEFINE_STATIC(struct pfilhookhead, pfil_hook_list) =
112     LIST_HEAD_INITIALIZER(pfil_hook_list);
113 #define	V_pfil_hook_list	VNET(pfil_hook_list)
114 
115 static struct pfil_link *pfil_link_remove(pfil_chain_t *, pfil_hook_t );
116 static void pfil_link_free(epoch_context_t);
117 
118 /*
119  * To couple a filtering point that provides memory pointer with a filter that
120  * works on mbufs only.
121  */
122 static __noinline int
123 pfil_fake_mbuf(pfil_mbuf_chk_t func, void *mem, u_int len, struct ifnet *ifp,
124     int flags, void *ruleset, struct mbuf **mp)
125 {
126 	struct mbuf m;
127 	pfil_return_t rv;
128 
129 	(void)m_init(&m, M_NOWAIT, MT_DATA, M_NOFREE | M_PKTHDR);
130 	m_extadd(&m, mem, len, NULL, NULL, NULL, 0, EXT_RXRING);
131 	m.m_len = m.m_pkthdr.len = len;
132 	*mp = &m;
133 
134 	rv = func(mp, ifp, flags, ruleset, NULL);
135 	if (rv == PFIL_PASS && *mp != &m) {
136 		/*
137 		 * Firewalls that need pfil_fake_mbuf() most likely don't
138 		 * know they need return PFIL_REALLOCED.
139 		 */
140 		rv = PFIL_REALLOCED;
141 	}
142 
143 	return (rv);
144 }
145 
146 static __always_inline int
147 pfil_mem_common(pfil_chain_t *pch, void *mem, u_int len, int flags,
148     struct ifnet *ifp, struct mbuf **m)
149 {
150 	struct pfil_link *link;
151 	pfil_return_t rv;
152 	bool realloc = false;
153 
154 	NET_EPOCH_ASSERT();
155 	KASSERT(flags == PFIL_IN || flags == PFIL_OUT,
156 	    ("%s: unsupported flags %d", __func__, flags));
157 
158 	rv = PFIL_PASS;
159 	CK_STAILQ_FOREACH(link, pch, link_chain) {
160 		if (__predict_true(link->link_mem_chk != NULL && !realloc))
161 			rv = link->link_mem_chk(mem, len, flags, ifp,
162 			    link->link_ruleset, m);
163 		else if (!realloc)
164 			rv = pfil_fake_mbuf(link->link_mbuf_chk, mem, len, ifp,
165 			    flags, link->link_ruleset, m);
166 		else
167 			rv = link->link_mbuf_chk(m, ifp, flags,
168 			    link->link_ruleset, NULL);
169 
170 		if (rv == PFIL_DROPPED || rv == PFIL_CONSUMED)
171 			break;
172 		else if (rv == PFIL_REALLOCED)
173 			realloc = true;
174 	}
175 	if (realloc && rv == PFIL_PASS)
176 		rv = PFIL_REALLOCED;
177 	return (rv);
178 }
179 
180 int
181 pfil_mem_in(struct pfil_head *head, void *mem, u_int len, struct ifnet *ifp,
182     struct mbuf **m)
183 {
184 
185 	return (pfil_mem_common(&head->head_in, mem, len, PFIL_IN, ifp, m));
186 }
187 
188 int
189 pfil_mem_out(struct pfil_head *head, void *mem, u_int len, struct ifnet *ifp,
190     struct mbuf **m)
191 {
192 
193 	return (pfil_mem_common(&head->head_out, mem, len, PFIL_OUT, ifp, m));
194 }
195 
196 static __always_inline int
197 pfil_mbuf_common(pfil_chain_t *pch, struct mbuf **m, struct ifnet *ifp,
198     int flags, struct inpcb *inp)
199 {
200 	struct pfil_link *link;
201 	pfil_return_t rv;
202 
203 	NET_EPOCH_ASSERT();
204 	KASSERT((flags & ~(PFIL_IN|PFIL_OUT|PFIL_FWD)) == 0,
205 	    ("%s: unsupported flags %#x", __func__, flags));
206 	KASSERT((flags & ~PFIL_FWD) == PFIL_IN ||
207 	    (flags & ~PFIL_FWD) == PFIL_OUT,
208 	    ("%s: conflicting directions %#x", __func__, flags));
209 
210 	rv = PFIL_PASS;
211 	CK_STAILQ_FOREACH(link, pch, link_chain) {
212 		rv = link->link_mbuf_chk(m, ifp, flags, link->link_ruleset,
213 		    inp);
214 		if (rv == PFIL_DROPPED || rv == PFIL_CONSUMED) {
215 			MPASS(*m == NULL);
216 			break;
217 		} else {
218 			MPASS(*m != NULL);
219 		}
220 	}
221 
222 	return (rv);
223 }
224 
225 int
226 pfil_mbuf_in(struct pfil_head *head, struct mbuf **m, struct ifnet *ifp,
227    struct inpcb *inp)
228 {
229 
230 	return (pfil_mbuf_common(&head->head_in, m, ifp, PFIL_IN, inp));
231 }
232 
233 int
234 pfil_mbuf_out(struct pfil_head *head, struct mbuf **m, struct ifnet *ifp,
235     struct inpcb *inp)
236 {
237 
238 	return (pfil_mbuf_common(&head->head_out, m, ifp, PFIL_OUT, inp));
239 }
240 
241 int
242 pfil_mbuf_fwd(struct pfil_head *head, struct mbuf **m, struct ifnet *ifp,
243     struct inpcb *inp)
244 {
245 
246 	return (pfil_mbuf_common(&head->head_out, m, ifp, PFIL_OUT | PFIL_FWD, inp));
247 }
248 
249 /*
250  * pfil_head_register() registers a pfil_head with the packet filter hook
251  * mechanism.
252  */
253 pfil_head_t
254 pfil_head_register(struct pfil_head_args *pa)
255 {
256 	struct pfil_head *head, *list;
257 
258 	MPASS(pa->pa_version == PFIL_VERSION);
259 
260 	head = malloc(sizeof(struct pfil_head), M_PFIL, M_WAITOK);
261 
262 	head->head_nhooksin = head->head_nhooksout = 0;
263 	head->head_flags = pa->pa_flags;
264 	head->head_type = pa->pa_type;
265 	head->head_name = pa->pa_headname;
266 	CK_STAILQ_INIT(&head->head_in);
267 	CK_STAILQ_INIT(&head->head_out);
268 
269 	PFIL_LOCK();
270 	LIST_FOREACH(list, &V_pfil_head_list, head_list)
271 		if (strcmp(pa->pa_headname, list->head_name) == 0) {
272 			printf("pfil: duplicate head \"%s\"\n",
273 			    pa->pa_headname);
274 		}
275 	LIST_INSERT_HEAD(&V_pfil_head_list, head, head_list);
276 	PFIL_UNLOCK();
277 
278 	return (head);
279 }
280 
281 /*
282  * pfil_head_unregister() removes a pfil_head from the packet filter hook
283  * mechanism.  The producer of the hook promises that all outstanding
284  * invocations of the hook have completed before it unregisters the hook.
285  */
286 void
287 pfil_head_unregister(pfil_head_t ph)
288 {
289 	struct pfil_link *link, *next;
290 
291 	PFIL_LOCK();
292 	LIST_REMOVE(ph, head_list);
293 
294 	CK_STAILQ_FOREACH_SAFE(link, &ph->head_in, link_chain, next) {
295 		link->link_hook->hook_links--;
296 		free(link, M_PFIL);
297 	}
298 	CK_STAILQ_FOREACH_SAFE(link, &ph->head_out, link_chain, next) {
299 		link->link_hook->hook_links--;
300 		free(link, M_PFIL);
301 	}
302 	PFIL_UNLOCK();
303 	free(ph, M_PFIL);
304 }
305 
306 pfil_hook_t
307 pfil_add_hook(struct pfil_hook_args *pa)
308 {
309 	struct pfil_hook *hook, *list;
310 
311 	MPASS(pa->pa_version == PFIL_VERSION);
312 
313 	hook = malloc(sizeof(struct pfil_hook), M_PFIL, M_WAITOK | M_ZERO);
314 	hook->hook_mbuf_chk = pa->pa_mbuf_chk;
315 	hook->hook_mem_chk = pa->pa_mem_chk;
316 	hook->hook_ruleset = pa->pa_ruleset;
317 	hook->hook_flags = pa->pa_flags;
318 	hook->hook_type = pa->pa_type;
319 	hook->hook_modname = pa->pa_modname;
320 	hook->hook_rulname = pa->pa_rulname;
321 
322 	PFIL_LOCK();
323 	LIST_FOREACH(list, &V_pfil_hook_list, hook_list)
324 		if (strcmp(pa->pa_modname, list->hook_modname) == 0 &&
325 		    strcmp(pa->pa_rulname, list->hook_rulname) == 0) {
326 			printf("pfil: duplicate hook \"%s:%s\"\n",
327 			    pa->pa_modname, pa->pa_rulname);
328 		}
329 	LIST_INSERT_HEAD(&V_pfil_hook_list, hook, hook_list);
330 	PFIL_UNLOCK();
331 
332 	return (hook);
333 }
334 
335 static int
336 pfil_unlink(struct pfil_link_args *pa, pfil_head_t head, pfil_hook_t hook)
337 {
338 	struct pfil_link *in, *out;
339 
340 	PFIL_LOCK_ASSERT();
341 
342 	if (pa->pa_flags & PFIL_IN) {
343 		in = pfil_link_remove(&head->head_in, hook);
344 		if (in != NULL) {
345 			head->head_nhooksin--;
346 			hook->hook_links--;
347 		}
348 	} else
349 		in = NULL;
350 	if (pa->pa_flags & PFIL_OUT) {
351 		out = pfil_link_remove(&head->head_out, hook);
352 		if (out != NULL) {
353 			head->head_nhooksout--;
354 			hook->hook_links--;
355 		}
356 	} else
357 		out = NULL;
358 	PFIL_UNLOCK();
359 
360 	if (in != NULL)
361 		NET_EPOCH_CALL(pfil_link_free, &in->link_epoch_ctx);
362 	if (out != NULL)
363 		NET_EPOCH_CALL(pfil_link_free, &out->link_epoch_ctx);
364 
365 	if (in == NULL && out == NULL)
366 		return (ENOENT);
367 	else
368 		return (0);
369 }
370 
371 int
372 pfil_link(struct pfil_link_args *pa)
373 {
374 	struct pfil_link *in, *out, *link;
375 	struct pfil_head *head;
376 	struct pfil_hook *hook;
377 	int error;
378 
379 	MPASS(pa->pa_version == PFIL_VERSION);
380 
381 	if ((pa->pa_flags & (PFIL_IN | PFIL_UNLINK)) == PFIL_IN)
382 		in = malloc(sizeof(*in), M_PFIL, M_WAITOK | M_ZERO);
383 	else
384 		in = NULL;
385 	if ((pa->pa_flags & (PFIL_OUT | PFIL_UNLINK)) == PFIL_OUT)
386 		out = malloc(sizeof(*out), M_PFIL, M_WAITOK | M_ZERO);
387 	else
388 		out = NULL;
389 
390 	PFIL_LOCK();
391 	if (pa->pa_flags & PFIL_HEADPTR)
392 		head = pa->pa_head;
393 	else
394 		LIST_FOREACH(head, &V_pfil_head_list, head_list)
395 			if (strcmp(pa->pa_headname, head->head_name) == 0)
396 				break;
397 	if (pa->pa_flags & PFIL_HOOKPTR)
398 		hook = pa->pa_hook;
399 	else
400 		LIST_FOREACH(hook, &V_pfil_hook_list, hook_list)
401 			if (strcmp(pa->pa_modname, hook->hook_modname) == 0 &&
402 			    strcmp(pa->pa_rulname, hook->hook_rulname) == 0)
403 				break;
404 	if (head == NULL || hook == NULL) {
405 		error = ENOENT;
406 		goto fail;
407 	}
408 
409 	if (pa->pa_flags & PFIL_UNLINK)
410 		return (pfil_unlink(pa, head, hook));
411 
412 	if (head->head_type != hook->hook_type ||
413 	    ((hook->hook_flags & pa->pa_flags) & ~head->head_flags)) {
414 		error = EINVAL;
415 		goto fail;
416 	}
417 
418 	if (pa->pa_flags & PFIL_IN)
419 		CK_STAILQ_FOREACH(link, &head->head_in, link_chain)
420 			if (link->link_hook == hook) {
421 				error = EEXIST;
422 				goto fail;
423 			}
424 	if (pa->pa_flags & PFIL_OUT)
425 		CK_STAILQ_FOREACH(link, &head->head_out, link_chain)
426 			if (link->link_hook == hook) {
427 				error = EEXIST;
428 				goto fail;
429 			}
430 
431 	if (pa->pa_flags & PFIL_IN) {
432 		in->link_hook = hook;
433 		in->link_mbuf_chk = hook->hook_mbuf_chk;
434 		in->link_mem_chk = hook->hook_mem_chk;
435 		in->link_flags = hook->hook_flags;
436 		in->link_ruleset = hook->hook_ruleset;
437 		if (pa->pa_flags & PFIL_APPEND)
438 			CK_STAILQ_INSERT_TAIL(&head->head_in, in, link_chain);
439 		else
440 			CK_STAILQ_INSERT_HEAD(&head->head_in, in, link_chain);
441 		hook->hook_links++;
442 		head->head_nhooksin++;
443 	}
444 	if (pa->pa_flags & PFIL_OUT) {
445 		out->link_hook = hook;
446 		out->link_mbuf_chk = hook->hook_mbuf_chk;
447 		out->link_mem_chk = hook->hook_mem_chk;
448 		out->link_flags = hook->hook_flags;
449 		out->link_ruleset = hook->hook_ruleset;
450 		if (pa->pa_flags & PFIL_APPEND)
451 			CK_STAILQ_INSERT_HEAD(&head->head_out, out, link_chain);
452 		else
453 			CK_STAILQ_INSERT_TAIL(&head->head_out, out, link_chain);
454 		hook->hook_links++;
455 		head->head_nhooksout++;
456 	}
457 	PFIL_UNLOCK();
458 
459 	return (0);
460 
461 fail:
462 	PFIL_UNLOCK();
463 	free(in, M_PFIL);
464 	free(out, M_PFIL);
465 	return (error);
466 }
467 
468 static void
469 pfil_link_free(epoch_context_t ctx)
470 {
471 	struct pfil_link *link;
472 
473 	link = __containerof(ctx, struct pfil_link, link_epoch_ctx);
474 	free(link, M_PFIL);
475 }
476 
477 /*
478  * pfil_remove_hook removes a filter from all filtering points.
479  */
480 void
481 pfil_remove_hook(pfil_hook_t hook)
482 {
483 	struct pfil_head *head;
484 	struct pfil_link *in, *out;
485 
486 	PFIL_LOCK();
487 	LIST_FOREACH(head, &V_pfil_head_list, head_list) {
488 retry:
489 		in = pfil_link_remove(&head->head_in, hook);
490 		if (in != NULL) {
491 			head->head_nhooksin--;
492 			hook->hook_links--;
493 			NET_EPOCH_CALL(pfil_link_free, &in->link_epoch_ctx);
494 		}
495 		out = pfil_link_remove(&head->head_out, hook);
496 		if (out != NULL) {
497 			head->head_nhooksout--;
498 			hook->hook_links--;
499 			NET_EPOCH_CALL(pfil_link_free, &out->link_epoch_ctx);
500 		}
501 		if (in != NULL || out != NULL)
502 			/* What if some stupid admin put same filter twice? */
503 			goto retry;
504 	}
505 	LIST_REMOVE(hook, hook_list);
506 	PFIL_UNLOCK();
507 	MPASS(hook->hook_links == 0);
508 	free(hook, M_PFIL);
509 }
510 
511 /*
512  * Internal: Remove a pfil hook from a hook chain.
513  */
514 static struct pfil_link *
515 pfil_link_remove(pfil_chain_t *chain, pfil_hook_t hook)
516 {
517 	struct pfil_link *link;
518 
519 	PFIL_LOCK_ASSERT();
520 
521 	CK_STAILQ_FOREACH(link, chain, link_chain)
522 		if (link->link_hook == hook) {
523 			CK_STAILQ_REMOVE(chain, link, pfil_link, link_chain);
524 			return (link);
525 		}
526 
527 	return (NULL);
528 }
529 
530 static void
531 pfil_init(const void *unused __unused)
532 {
533 	struct make_dev_args args;
534 	int error __diagused;
535 
536 	make_dev_args_init(&args);
537 	args.mda_flags = MAKEDEV_WAITOK | MAKEDEV_CHECKNAME;
538 	args.mda_devsw = &pfil_cdevsw;
539 	args.mda_uid = UID_ROOT;
540 	args.mda_gid = GID_WHEEL;
541 	args.mda_mode = 0600;
542 	error = make_dev_s(&args, &pfil_dev, PFILDEV);
543 	KASSERT(error == 0, ("%s: failed to create dev: %d", __func__, error));
544 }
545 /*
546  * Make sure the pfil bits are first before any possible subsystem which
547  * might piggyback on the SI_SUB_PROTO_PFIL.
548  */
549 SYSINIT(pfil_init, SI_SUB_PROTO_PFIL, SI_ORDER_FIRST, pfil_init, NULL);
550 
551 /*
552  * User control interface.
553  */
554 static int pfilioc_listheads(struct pfilioc_list *);
555 static int pfilioc_listhooks(struct pfilioc_list *);
556 static int pfilioc_link(struct pfilioc_link *);
557 
558 static int
559 pfil_ioctl(struct cdev *dev, u_long cmd, caddr_t addr, int flags,
560     struct thread *td)
561 {
562 	int error;
563 
564 	CURVNET_SET(TD_TO_VNET(td));
565 	error = 0;
566 	switch (cmd) {
567 	case PFILIOC_LISTHEADS:
568 		error = pfilioc_listheads((struct pfilioc_list *)addr);
569 		break;
570 	case PFILIOC_LISTHOOKS:
571 		error = pfilioc_listhooks((struct pfilioc_list *)addr);
572 		break;
573 	case PFILIOC_LINK:
574 		error = pfilioc_link((struct pfilioc_link *)addr);
575 		break;
576 	default:
577 		error = EINVAL;
578 		break;
579 	}
580 	CURVNET_RESTORE();
581 	return (error);
582 }
583 
584 static int
585 pfilioc_listheads(struct pfilioc_list *req)
586 {
587 	struct pfil_head *head;
588 	struct pfil_link *link;
589 	struct pfilioc_head *iohead;
590 	struct pfilioc_hook *iohook;
591 	u_int nheads, nhooks, hd, hk;
592 	int error;
593 
594 	PFIL_LOCK();
595 restart:
596 	nheads = nhooks = 0;
597 	LIST_FOREACH(head, &V_pfil_head_list, head_list) {
598 		nheads++;
599 		nhooks += head->head_nhooksin + head->head_nhooksout;
600 	}
601 	PFIL_UNLOCK();
602 
603 	if (req->pio_nheads < nheads || req->pio_nhooks < nhooks) {
604 		req->pio_nheads = nheads;
605 		req->pio_nhooks = nhooks;
606 		return (0);
607 	}
608 
609 	iohead = malloc(sizeof(*iohead) * nheads, M_TEMP, M_WAITOK);
610 	iohook = malloc(sizeof(*iohook) * nhooks, M_TEMP, M_WAITOK);
611 
612 	hd = hk = 0;
613 	PFIL_LOCK();
614 	LIST_FOREACH(head, &V_pfil_head_list, head_list) {
615 		if (hd + 1 > nheads ||
616 		    hk + head->head_nhooksin + head->head_nhooksout > nhooks) {
617 			/* Configuration changed during malloc(). */
618 			free(iohead, M_TEMP);
619 			free(iohook, M_TEMP);
620 			goto restart;
621 		}
622 		strlcpy(iohead[hd].pio_name, head->head_name,
623 			sizeof(iohead[0].pio_name));
624 		iohead[hd].pio_nhooksin = head->head_nhooksin;
625 		iohead[hd].pio_nhooksout = head->head_nhooksout;
626 		iohead[hd].pio_type = head->head_type;
627 		CK_STAILQ_FOREACH(link, &head->head_in, link_chain) {
628 			strlcpy(iohook[hk].pio_module,
629 			    link->link_hook->hook_modname,
630 			    sizeof(iohook[0].pio_module));
631 			strlcpy(iohook[hk].pio_ruleset,
632 			    link->link_hook->hook_rulname,
633 			    sizeof(iohook[0].pio_ruleset));
634 			hk++;
635 		}
636 		CK_STAILQ_FOREACH(link, &head->head_out, link_chain) {
637 			strlcpy(iohook[hk].pio_module,
638 			    link->link_hook->hook_modname,
639 			    sizeof(iohook[0].pio_module));
640 			strlcpy(iohook[hk].pio_ruleset,
641 			    link->link_hook->hook_rulname,
642 			    sizeof(iohook[0].pio_ruleset));
643 			hk++;
644 		}
645 		hd++;
646 	}
647 	PFIL_UNLOCK();
648 
649 	error = copyout(iohead, req->pio_heads,
650 	    sizeof(*iohead) * min(hd, req->pio_nheads));
651 	if (error == 0)
652 		error = copyout(iohook, req->pio_hooks,
653 		    sizeof(*iohook) * min(req->pio_nhooks, hk));
654 
655 	req->pio_nheads = hd;
656 	req->pio_nhooks = hk;
657 
658 	free(iohead, M_TEMP);
659 	free(iohook, M_TEMP);
660 
661 	return (error);
662 }
663 
664 static int
665 pfilioc_listhooks(struct pfilioc_list *req)
666 {
667 	struct pfil_hook *hook;
668 	struct pfilioc_hook *iohook;
669 	u_int nhooks, hk;
670 	int error;
671 
672 	PFIL_LOCK();
673 restart:
674 	nhooks = 0;
675 	LIST_FOREACH(hook, &V_pfil_hook_list, hook_list)
676 		nhooks++;
677 	PFIL_UNLOCK();
678 
679 	if (req->pio_nhooks < nhooks) {
680 		req->pio_nhooks = nhooks;
681 		return (0);
682 	}
683 
684 	iohook = malloc(sizeof(*iohook) * nhooks, M_TEMP, M_WAITOK);
685 
686 	hk = 0;
687 	PFIL_LOCK();
688 	LIST_FOREACH(hook, &V_pfil_hook_list, hook_list) {
689 		if (hk + 1 > nhooks) {
690 			/* Configuration changed during malloc(). */
691 			free(iohook, M_TEMP);
692 			goto restart;
693 		}
694 		strlcpy(iohook[hk].pio_module, hook->hook_modname,
695 		    sizeof(iohook[0].pio_module));
696 		strlcpy(iohook[hk].pio_ruleset, hook->hook_rulname,
697 		    sizeof(iohook[0].pio_ruleset));
698 		iohook[hk].pio_type = hook->hook_type;
699 		iohook[hk].pio_flags = hook->hook_flags;
700 		hk++;
701 	}
702 	PFIL_UNLOCK();
703 
704 	error = copyout(iohook, req->pio_hooks,
705 	    sizeof(*iohook) * min(req->pio_nhooks, hk));
706 	req->pio_nhooks = hk;
707 	free(iohook, M_TEMP);
708 
709 	return (error);
710 }
711 
712 static int
713 pfilioc_link(struct pfilioc_link *req)
714 {
715 	struct pfil_link_args args;
716 
717 	if (req->pio_flags & ~(PFIL_IN | PFIL_OUT | PFIL_UNLINK | PFIL_APPEND))
718 		return (EINVAL);
719 
720 	args.pa_version = PFIL_VERSION;
721 	args.pa_flags = req->pio_flags;
722 	args.pa_headname = req->pio_name;
723 	args.pa_modname = req->pio_module;
724 	args.pa_rulname = req->pio_ruleset;
725 
726 	return (pfil_link(&args));
727 }
728