xref: /freebsd/sys/netgraph/ng_patch.c (revision 0b57cec536236d46e3dba9bd041533462f33dbb7)
1 /*-
2  * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
3  *
4  * Copyright (c) 2010 Maxim Ignatenko <gelraen.ua@gmail.com>
5  * Copyright (c) 2015 Dmitry Vagin <daemon.hammer@ya.ru>
6  * All rights reserved.
7  *
8  * Redistribution and use in source and binary forms, with or without
9  * modification, are permitted provided that the following conditions
10  * are met:
11  * 1. Redistributions of source code must retain the above copyright
12  *    notice, this list of conditions and the following disclaimer.
13  * 2. Redistributions in binary form must reproduce the above copyright
14  *    notice, this list of conditions and the following disclaimer in the
15  *    documentation and/or other materials provided with the distribution.
16  *
17  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27  * SUCH DAMAGE.
28  *
29  */
30 
31 #include <sys/cdefs.h>
32 __FBSDID("$FreeBSD$");
33 
34 #include <sys/param.h>
35 #include <sys/systm.h>
36 #include <sys/kernel.h>
37 #include <sys/endian.h>
38 #include <sys/malloc.h>
39 #include <sys/mbuf.h>
40 
41 #include <net/bpf.h>
42 #include <net/ethernet.h>
43 
44 #include <netgraph/ng_message.h>
45 #include <netgraph/ng_parse.h>
46 #include <netgraph/netgraph.h>
47 
48 #include <netgraph/ng_patch.h>
49 
50 /* private data */
51 struct ng_patch_priv {
52 	hook_p		in;
53 	hook_p		out;
54 	uint8_t		dlt;	/* DLT_XXX from bpf.h */
55 	struct ng_patch_stats stats;
56 	struct ng_patch_config *conf;
57 };
58 
59 typedef struct ng_patch_priv *priv_p;
60 
61 /* Netgraph methods */
62 static ng_constructor_t	ng_patch_constructor;
63 static ng_rcvmsg_t	ng_patch_rcvmsg;
64 static ng_shutdown_t	ng_patch_shutdown;
65 static ng_newhook_t	ng_patch_newhook;
66 static ng_rcvdata_t	ng_patch_rcvdata;
67 static ng_disconnect_t	ng_patch_disconnect;
68 
69 #define ERROUT(x) { error = (x); goto done; }
70 
71 static int
72 ng_patch_config_getlen(const struct ng_parse_type *type,
73     const u_char *start, const u_char *buf)
74 {
75 	const struct ng_patch_config *conf;
76 
77 	conf = (const struct ng_patch_config *)(buf -
78 	    offsetof(struct ng_patch_config, ops));
79 
80 	return (conf->count);
81 }
82 
83 static const struct ng_parse_struct_field ng_patch_op_type_fields[]
84 	= NG_PATCH_OP_TYPE;
85 static const struct ng_parse_type ng_patch_op_type = {
86 	&ng_parse_struct_type,
87 	&ng_patch_op_type_fields
88 };
89 
90 static const struct ng_parse_array_info ng_patch_ops_array_info = {
91 	&ng_patch_op_type,
92 	&ng_patch_config_getlen
93 };
94 static const struct ng_parse_type ng_patch_ops_array_type = {
95 	&ng_parse_array_type,
96 	&ng_patch_ops_array_info
97 };
98 
99 static const struct ng_parse_struct_field ng_patch_config_type_fields[]
100 	= NG_PATCH_CONFIG_TYPE;
101 static const struct ng_parse_type ng_patch_config_type = {
102 	&ng_parse_struct_type,
103 	&ng_patch_config_type_fields
104 };
105 
106 static const struct ng_parse_struct_field ng_patch_stats_fields[]
107 	= NG_PATCH_STATS_TYPE;
108 static const struct ng_parse_type ng_patch_stats_type = {
109 	&ng_parse_struct_type,
110 	&ng_patch_stats_fields
111 };
112 
113 static const struct ng_cmdlist ng_patch_cmdlist[] = {
114 	{
115 		NGM_PATCH_COOKIE,
116 		NGM_PATCH_GETDLT,
117 		"getdlt",
118 		NULL,
119 		&ng_parse_uint8_type
120 	},
121 	{
122 		NGM_PATCH_COOKIE,
123 		NGM_PATCH_SETDLT,
124 		"setdlt",
125 		&ng_parse_uint8_type,
126 		NULL
127 	},
128 	{
129 		NGM_PATCH_COOKIE,
130 		NGM_PATCH_GETCONFIG,
131 		"getconfig",
132 		NULL,
133 		&ng_patch_config_type
134 	},
135 	{
136 		NGM_PATCH_COOKIE,
137 		NGM_PATCH_SETCONFIG,
138 		"setconfig",
139 		&ng_patch_config_type,
140 		NULL
141 	},
142 	{
143 		NGM_PATCH_COOKIE,
144 		NGM_PATCH_GET_STATS,
145 		"getstats",
146 		NULL,
147 		&ng_patch_stats_type
148 	},
149 	{
150 		NGM_PATCH_COOKIE,
151 		NGM_PATCH_CLR_STATS,
152 		"clrstats",
153 		NULL,
154 		NULL
155 	},
156 	{
157 		NGM_PATCH_COOKIE,
158 		NGM_PATCH_GETCLR_STATS,
159 		"getclrstats",
160 		NULL,
161 		&ng_patch_stats_type
162 	},
163 	{ 0 }
164 };
165 
166 static struct ng_type typestruct = {
167 	.version =	NG_ABI_VERSION,
168 	.name =		NG_PATCH_NODE_TYPE,
169 	.constructor =	ng_patch_constructor,
170 	.rcvmsg =	ng_patch_rcvmsg,
171 	.shutdown =	ng_patch_shutdown,
172 	.newhook =	ng_patch_newhook,
173 	.rcvdata =	ng_patch_rcvdata,
174 	.disconnect =	ng_patch_disconnect,
175 	.cmdlist =	ng_patch_cmdlist,
176 };
177 
178 NETGRAPH_INIT(patch, &typestruct);
179 
180 static int
181 ng_patch_constructor(node_p node)
182 {
183 	priv_p privdata;
184 
185 	privdata = malloc(sizeof(*privdata), M_NETGRAPH, M_WAITOK | M_ZERO);
186 	privdata->dlt = DLT_RAW;
187 
188 	NG_NODE_SET_PRIVATE(node, privdata);
189 
190 	return (0);
191 }
192 
193 static int
194 ng_patch_newhook(node_p node, hook_p hook, const char *name)
195 {
196 	const priv_p privp = NG_NODE_PRIVATE(node);
197 
198 	if (strncmp(name, NG_PATCH_HOOK_IN, strlen(NG_PATCH_HOOK_IN)) == 0) {
199 		privp->in = hook;
200 	} else if (strncmp(name, NG_PATCH_HOOK_OUT,
201 	    strlen(NG_PATCH_HOOK_OUT)) == 0) {
202 		privp->out = hook;
203 	} else
204 		return (EINVAL);
205 
206 	return (0);
207 }
208 
209 static int
210 ng_patch_rcvmsg(node_p node, item_p item, hook_p lasthook)
211 {
212 	const priv_p privp = NG_NODE_PRIVATE(node);
213 	struct ng_patch_config *conf, *newconf;
214 	struct ng_mesg *msg;
215 	struct ng_mesg *resp = NULL;
216 	int i, error = 0;
217 
218 	NGI_GET_MSG(item, msg);
219 
220 	if  (msg->header.typecookie != NGM_PATCH_COOKIE)
221 		ERROUT(EINVAL);
222 
223 	switch (msg->header.cmd)
224 	{
225 		case NGM_PATCH_GETCONFIG:
226 			if (privp->conf == NULL)
227 				ERROUT(0);
228 
229 			NG_MKRESPONSE(resp, msg,
230 			    NG_PATCH_CONF_SIZE(privp->conf->count), M_WAITOK);
231 
232 			if (resp == NULL)
233 				ERROUT(ENOMEM);
234 
235 			bcopy(privp->conf, resp->data,
236 			    NG_PATCH_CONF_SIZE(privp->conf->count));
237 
238 			conf = (struct ng_patch_config *) resp->data;
239 
240 			for (i = 0; i < conf->count; i++) {
241 				switch (conf->ops[i].length)
242 				{
243 					case 1:
244 						conf->ops[i].val.v8 = conf->ops[i].val.v1;
245 						break;
246 					case 2:
247 						conf->ops[i].val.v8 = conf->ops[i].val.v2;
248 						break;
249 					case 4:
250 						conf->ops[i].val.v8 = conf->ops[i].val.v4;
251 						break;
252 					case 8:
253 						break;
254 				}
255 			}
256 
257 			break;
258 
259 		case NGM_PATCH_SETCONFIG:
260 			conf = (struct ng_patch_config *) msg->data;
261 
262 			if (msg->header.arglen < sizeof(struct ng_patch_config) ||
263 			    msg->header.arglen < NG_PATCH_CONF_SIZE(conf->count))
264 				ERROUT(EINVAL);
265 
266 			for (i = 0; i < conf->count; i++) {
267 				switch (conf->ops[i].length)
268 				{
269 					case 1:
270 						conf->ops[i].val.v1 = (uint8_t) conf->ops[i].val.v8;
271 						break;
272 					case 2:
273 						conf->ops[i].val.v2 = (uint16_t) conf->ops[i].val.v8;
274 						break;
275 					case 4:
276 						conf->ops[i].val.v4 = (uint32_t) conf->ops[i].val.v8;
277 						break;
278 					case 8:
279 						break;
280 					default:
281 						ERROUT(EINVAL);
282 				}
283 			}
284 
285 			conf->csum_flags &= NG_PATCH_CSUM_IPV4|NG_PATCH_CSUM_IPV6;
286 			conf->relative_offset = !!conf->relative_offset;
287 
288 			newconf = malloc(NG_PATCH_CONF_SIZE(conf->count), M_NETGRAPH, M_WAITOK | M_ZERO);
289 
290 			bcopy(conf, newconf, NG_PATCH_CONF_SIZE(conf->count));
291 
292 			if (privp->conf)
293 				free(privp->conf, M_NETGRAPH);
294 
295 			privp->conf = newconf;
296 
297 			break;
298 
299 		case NGM_PATCH_GET_STATS:
300 		case NGM_PATCH_CLR_STATS:
301 		case NGM_PATCH_GETCLR_STATS:
302 			if (msg->header.cmd != NGM_PATCH_CLR_STATS) {
303 				NG_MKRESPONSE(resp, msg, sizeof(struct ng_patch_stats), M_WAITOK);
304 
305 				if (resp == NULL)
306 					ERROUT(ENOMEM);
307 
308 				bcopy(&(privp->stats), resp->data, sizeof(struct ng_patch_stats));
309 			}
310 
311 			if (msg->header.cmd != NGM_PATCH_GET_STATS)
312 				bzero(&(privp->stats), sizeof(struct ng_patch_stats));
313 
314 			break;
315 
316 		case NGM_PATCH_GETDLT:
317 			NG_MKRESPONSE(resp, msg, sizeof(uint8_t), M_WAITOK);
318 
319 			if (resp == NULL)
320 				ERROUT(ENOMEM);
321 
322 			*((uint8_t *) resp->data) = privp->dlt;
323 
324 			break;
325 
326 		case NGM_PATCH_SETDLT:
327 			if (msg->header.arglen != sizeof(uint8_t))
328 				ERROUT(EINVAL);
329 
330 			switch (*(uint8_t *) msg->data)
331 			{
332 				case DLT_EN10MB:
333 				case DLT_RAW:
334 					privp->dlt = *(uint8_t *) msg->data;
335 					break;
336 
337 				default:
338 					ERROUT(EINVAL);
339 			}
340 
341 			break;
342 
343 		default:
344 			ERROUT(EINVAL);
345 	}
346 
347 done:
348 	NG_RESPOND_MSG(error, node, item, resp);
349 	NG_FREE_MSG(msg);
350 
351 	return (error);
352 }
353 
354 static void
355 do_patch(priv_p privp, struct mbuf *m, int global_offset)
356 {
357 	int i, offset, patched = 0;
358 	union ng_patch_op_val val;
359 
360 	for (i = 0; i < privp->conf->count; i++) {
361 		offset = global_offset + privp->conf->ops[i].offset;
362 
363 		if (offset + privp->conf->ops[i].length > m->m_pkthdr.len)
364 			continue;
365 
366 		/* for "=" operation we don't need to copy data from mbuf */
367 		if (privp->conf->ops[i].mode != NG_PATCH_MODE_SET)
368 			m_copydata(m, offset, privp->conf->ops[i].length, (caddr_t) &val);
369 
370 		switch (privp->conf->ops[i].length)
371 		{
372 			case 1:
373 				switch (privp->conf->ops[i].mode)
374 				{
375 					case NG_PATCH_MODE_SET:
376 						val.v1 = privp->conf->ops[i].val.v1;
377 						break;
378 					case NG_PATCH_MODE_ADD:
379 						val.v1 += privp->conf->ops[i].val.v1;
380 						break;
381 					case NG_PATCH_MODE_SUB:
382 						val.v1 -= privp->conf->ops[i].val.v1;
383 						break;
384 					case NG_PATCH_MODE_MUL:
385 						val.v1 *= privp->conf->ops[i].val.v1;
386 						break;
387 					case NG_PATCH_MODE_DIV:
388 						val.v1 /= privp->conf->ops[i].val.v1;
389 						break;
390 					case NG_PATCH_MODE_NEG:
391 						*((int8_t *) &val) = - *((int8_t *) &val);
392 						break;
393 					case NG_PATCH_MODE_AND:
394 						val.v1 &= privp->conf->ops[i].val.v1;
395 						break;
396 					case NG_PATCH_MODE_OR:
397 						val.v1 |= privp->conf->ops[i].val.v1;
398 						break;
399 					case NG_PATCH_MODE_XOR:
400 						val.v1 ^= privp->conf->ops[i].val.v1;
401 						break;
402 					case NG_PATCH_MODE_SHL:
403 						val.v1 <<= privp->conf->ops[i].val.v1;
404 						break;
405 					case NG_PATCH_MODE_SHR:
406 						val.v1 >>= privp->conf->ops[i].val.v1;
407 						break;
408 				}
409 				break;
410 
411 			case 2:
412 				val.v2 = ntohs(val.v2);
413 
414 				switch (privp->conf->ops[i].mode)
415 				{
416 					case NG_PATCH_MODE_SET:
417 						val.v2 = privp->conf->ops[i].val.v2;
418 						break;
419 					case NG_PATCH_MODE_ADD:
420 						val.v2 += privp->conf->ops[i].val.v2;
421 						break;
422 					case NG_PATCH_MODE_SUB:
423 						val.v2 -= privp->conf->ops[i].val.v2;
424 						break;
425 					case NG_PATCH_MODE_MUL:
426 						val.v2 *= privp->conf->ops[i].val.v2;
427 						break;
428 					case NG_PATCH_MODE_DIV:
429 						val.v2 /= privp->conf->ops[i].val.v2;
430 						break;
431 					case NG_PATCH_MODE_NEG:
432 						*((int16_t *) &val) = - *((int16_t *) &val);
433 						break;
434 					case NG_PATCH_MODE_AND:
435 						val.v2 &= privp->conf->ops[i].val.v2;
436 						break;
437 					case NG_PATCH_MODE_OR:
438 						val.v2 |= privp->conf->ops[i].val.v2;
439 						break;
440 					case NG_PATCH_MODE_XOR:
441 						val.v2 ^= privp->conf->ops[i].val.v2;
442 						break;
443 					case NG_PATCH_MODE_SHL:
444 						val.v2 <<= privp->conf->ops[i].val.v2;
445 						break;
446 					case NG_PATCH_MODE_SHR:
447 						val.v2 >>= privp->conf->ops[i].val.v2;
448 						break;
449 				}
450 
451 				val.v2 = htons(val.v2);
452 
453 				break;
454 
455 			case 4:
456 				val.v4 = ntohl(val.v4);
457 
458 				switch (privp->conf->ops[i].mode)
459 				{
460 					case NG_PATCH_MODE_SET:
461 						val.v4 = privp->conf->ops[i].val.v4;
462 						break;
463 					case NG_PATCH_MODE_ADD:
464 						val.v4 += privp->conf->ops[i].val.v4;
465 						break;
466 					case NG_PATCH_MODE_SUB:
467 						val.v4 -= privp->conf->ops[i].val.v4;
468 						break;
469 					case NG_PATCH_MODE_MUL:
470 						val.v4 *= privp->conf->ops[i].val.v4;
471 						break;
472 					case NG_PATCH_MODE_DIV:
473 						val.v4 /= privp->conf->ops[i].val.v4;
474 						break;
475 					case NG_PATCH_MODE_NEG:
476 						*((int32_t *) &val) = - *((int32_t *) &val);
477 						break;
478 					case NG_PATCH_MODE_AND:
479 						val.v4 &= privp->conf->ops[i].val.v4;
480 						break;
481 					case NG_PATCH_MODE_OR:
482 						val.v4 |= privp->conf->ops[i].val.v4;
483 						break;
484 					case NG_PATCH_MODE_XOR:
485 						val.v4 ^= privp->conf->ops[i].val.v4;
486 						break;
487 					case NG_PATCH_MODE_SHL:
488 						val.v4 <<= privp->conf->ops[i].val.v4;
489 						break;
490 					case NG_PATCH_MODE_SHR:
491 						val.v4 >>= privp->conf->ops[i].val.v4;
492 						break;
493 				}
494 
495 				val.v4 = htonl(val.v4);
496 
497 				break;
498 
499 			case 8:
500 				val.v8 = be64toh(val.v8);
501 
502 				switch (privp->conf->ops[i].mode)
503 				{
504 					case NG_PATCH_MODE_SET:
505 						val.v8 = privp->conf->ops[i].val.v8;
506 						break;
507 					case NG_PATCH_MODE_ADD:
508 						val.v8 += privp->conf->ops[i].val.v8;
509 						break;
510 					case NG_PATCH_MODE_SUB:
511 						val.v8 -= privp->conf->ops[i].val.v8;
512 						break;
513 					case NG_PATCH_MODE_MUL:
514 						val.v8 *= privp->conf->ops[i].val.v8;
515 						break;
516 					case NG_PATCH_MODE_DIV:
517 						val.v8 /= privp->conf->ops[i].val.v8;
518 						break;
519 					case NG_PATCH_MODE_NEG:
520 						*((int64_t *) &val) = - *((int64_t *) &val);
521 						break;
522 					case NG_PATCH_MODE_AND:
523 						val.v8 &= privp->conf->ops[i].val.v8;
524 						break;
525 					case NG_PATCH_MODE_OR:
526 						val.v8 |= privp->conf->ops[i].val.v8;
527 						break;
528 					case NG_PATCH_MODE_XOR:
529 						val.v8 ^= privp->conf->ops[i].val.v8;
530 						break;
531 					case NG_PATCH_MODE_SHL:
532 						val.v8 <<= privp->conf->ops[i].val.v8;
533 						break;
534 					case NG_PATCH_MODE_SHR:
535 						val.v8 >>= privp->conf->ops[i].val.v8;
536 						break;
537 				}
538 
539 				val.v8 = htobe64(val.v8);
540 
541 				break;
542 		}
543 
544 		m_copyback(m, offset, privp->conf->ops[i].length, (caddr_t) &val);
545 		patched = 1;
546 	}
547 
548 	if (patched)
549 		privp->stats.patched++;
550 }
551 
552 static int
553 ng_patch_rcvdata(hook_p hook, item_p item)
554 {
555 	const priv_p priv = NG_NODE_PRIVATE(NG_HOOK_NODE(hook));
556 	struct mbuf *m;
557 	hook_p out;
558 	int pullup_len = 0;
559 	int error = 0;
560 
561 	priv->stats.received++;
562 
563 	NGI_GET_M(item, m);
564 
565 #define	PULLUP_CHECK(mbuf, length) do {					\
566 	pullup_len += length;						\
567 	if (((mbuf)->m_pkthdr.len < pullup_len) ||			\
568 	    (pullup_len > MHLEN)) {					\
569 		error = EINVAL;						\
570 		goto bypass;						\
571 	}								\
572 	if ((mbuf)->m_len < pullup_len &&				\
573 	    (((mbuf) = m_pullup((mbuf), pullup_len)) == NULL)) {	\
574 		error = ENOBUFS;					\
575 		goto drop;						\
576 	}								\
577 } while (0)
578 
579 	if (priv->conf && hook == priv->in &&
580 	    m && (m->m_flags & M_PKTHDR)) {
581 
582 		m = m_unshare(m, M_NOWAIT);
583 
584 		if (m == NULL)
585 			ERROUT(ENOMEM);
586 
587 		if (priv->conf->relative_offset) {
588 			struct ether_header *eh;
589 			struct ng_patch_vlan_header *vh;
590 			uint16_t etype;
591 
592 			switch (priv->dlt)
593 			{
594 				case DLT_EN10MB:
595 					PULLUP_CHECK(m, sizeof(struct ether_header));
596 					eh = mtod(m, struct ether_header *);
597 					etype = ntohs(eh->ether_type);
598 
599 					for (;;) {	/* QinQ support */
600 						switch (etype)
601 						{
602 							case 0x8100:
603 							case 0x88A8:
604 							case 0x9100:
605 								PULLUP_CHECK(m, sizeof(struct ng_patch_vlan_header));
606 								vh = (struct ng_patch_vlan_header *) mtodo(m,
607 								    pullup_len - sizeof(struct ng_patch_vlan_header));
608 								etype = ntohs(vh->etype);
609 								break;
610 
611 							default:
612 								goto loopend;
613 						}
614 					}
615 loopend:
616 					break;
617 
618 				case DLT_RAW:
619 					break;
620 
621 				default:
622 					ERROUT(EINVAL);
623 			}
624 		}
625 
626 		do_patch(priv, m, pullup_len);
627 
628 		m->m_pkthdr.csum_flags |= priv->conf->csum_flags;
629 	}
630 
631 #undef	PULLUP_CHECK
632 
633 bypass:
634 	out = NULL;
635 
636 	if (hook == priv->in) {
637 		/* return frames on 'in' hook if 'out' not connected */
638 		out = priv->out ? priv->out : priv->in;
639 	} else if (hook == priv->out && priv->in) {
640 		/* pass frames on 'out' hook if 'in' connected */
641 		out = priv->in;
642 	}
643 
644 	if (out == NULL)
645 		ERROUT(0);
646 
647 	NG_FWD_NEW_DATA(error, item, out, m);
648 
649 	return (error);
650 
651 done:
652 drop:
653 	NG_FREE_ITEM(item);
654 	NG_FREE_M(m);
655 
656 	priv->stats.dropped++;
657 
658 	return (error);
659 }
660 
661 static int
662 ng_patch_shutdown(node_p node)
663 {
664 	const priv_p privdata = NG_NODE_PRIVATE(node);
665 
666 	NG_NODE_SET_PRIVATE(node, NULL);
667 	NG_NODE_UNREF(node);
668 
669 	if (privdata->conf != NULL)
670 		free(privdata->conf, M_NETGRAPH);
671 
672 	free(privdata, M_NETGRAPH);
673 
674 	return (0);
675 }
676 
677 static int
678 ng_patch_disconnect(hook_p hook)
679 {
680 	priv_p priv;
681 
682 	priv = NG_NODE_PRIVATE(NG_HOOK_NODE(hook));
683 
684 	if (hook == priv->in) {
685 		priv->in = NULL;
686 	}
687 
688 	if (hook == priv->out) {
689 		priv->out = NULL;
690 	}
691 
692 	if (NG_NODE_NUMHOOKS(NG_HOOK_NODE(hook)) == 0 &&
693 	    NG_NODE_IS_VALID(NG_HOOK_NODE(hook))) /* already shutting down? */
694 		ng_rmnode_self(NG_HOOK_NODE(hook));
695 
696 	return (0);
697 }
698