xref: /freebsd/sys/netgraph/ng_patch.c (revision e0c4386e7e71d93b0edc0c8fa156263fc4a8b0b6)
1 /*-
2  * SPDX-License-Identifier: BSD-2-Clause
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/param.h>
32 #include <sys/systm.h>
33 #include <sys/kernel.h>
34 #include <sys/endian.h>
35 #include <sys/malloc.h>
36 #include <sys/mbuf.h>
37 
38 #include <net/bpf.h>
39 #include <net/ethernet.h>
40 
41 #include <netgraph/ng_message.h>
42 #include <netgraph/ng_parse.h>
43 #include <netgraph/netgraph.h>
44 
45 #include <netgraph/ng_patch.h>
46 
47 /* private data */
48 struct ng_patch_priv {
49 	hook_p		in;
50 	hook_p		out;
51 	uint8_t		dlt;	/* DLT_XXX from bpf.h */
52 	struct ng_patch_stats stats;
53 	struct ng_patch_config *conf;
54 };
55 
56 typedef struct ng_patch_priv *priv_p;
57 
58 /* Netgraph methods */
59 static ng_constructor_t	ng_patch_constructor;
60 static ng_rcvmsg_t	ng_patch_rcvmsg;
61 static ng_shutdown_t	ng_patch_shutdown;
62 static ng_newhook_t	ng_patch_newhook;
63 static ng_rcvdata_t	ng_patch_rcvdata;
64 static ng_disconnect_t	ng_patch_disconnect;
65 #define ERROUT(x) { error = (x); goto done; }
66 
67 static int
68 ng_patch_config_getlen(const struct ng_parse_type *type,
69     const u_char *start, const u_char *buf)
70 {
71 	const struct ng_patch_config *conf;
72 
73 	conf = (const struct ng_patch_config *)(buf -
74 	    offsetof(struct ng_patch_config, ops));
75 
76 	return (conf->count);
77 }
78 
79 static const struct ng_parse_struct_field ng_patch_op_type_fields[]
80 	= NG_PATCH_OP_TYPE;
81 static const struct ng_parse_type ng_patch_op_type = {
82 	&ng_parse_struct_type,
83 	&ng_patch_op_type_fields
84 };
85 
86 static const struct ng_parse_array_info ng_patch_ops_array_info = {
87 	&ng_patch_op_type,
88 	&ng_patch_config_getlen
89 };
90 static const struct ng_parse_type ng_patch_ops_array_type = {
91 	&ng_parse_array_type,
92 	&ng_patch_ops_array_info
93 };
94 
95 static const struct ng_parse_struct_field ng_patch_config_type_fields[]
96 	= NG_PATCH_CONFIG_TYPE;
97 static const struct ng_parse_type ng_patch_config_type = {
98 	&ng_parse_struct_type,
99 	&ng_patch_config_type_fields
100 };
101 
102 static const struct ng_parse_struct_field ng_patch_stats_fields[]
103 	= NG_PATCH_STATS_TYPE;
104 static const struct ng_parse_type ng_patch_stats_type = {
105 	&ng_parse_struct_type,
106 	&ng_patch_stats_fields
107 };
108 
109 static const struct ng_cmdlist ng_patch_cmdlist[] = {
110 	{
111 		NGM_PATCH_COOKIE,
112 		NGM_PATCH_GETDLT,
113 		"getdlt",
114 		NULL,
115 		&ng_parse_uint8_type
116 	},
117 	{
118 		NGM_PATCH_COOKIE,
119 		NGM_PATCH_SETDLT,
120 		"setdlt",
121 		&ng_parse_uint8_type,
122 		NULL
123 	},
124 	{
125 		NGM_PATCH_COOKIE,
126 		NGM_PATCH_GETCONFIG,
127 		"getconfig",
128 		NULL,
129 		&ng_patch_config_type
130 	},
131 	{
132 		NGM_PATCH_COOKIE,
133 		NGM_PATCH_SETCONFIG,
134 		"setconfig",
135 		&ng_patch_config_type,
136 		NULL
137 	},
138 	{
139 		NGM_PATCH_COOKIE,
140 		NGM_PATCH_GET_STATS,
141 		"getstats",
142 		NULL,
143 		&ng_patch_stats_type
144 	},
145 	{
146 		NGM_PATCH_COOKIE,
147 		NGM_PATCH_CLR_STATS,
148 		"clrstats",
149 		NULL,
150 		NULL
151 	},
152 	{
153 		NGM_PATCH_COOKIE,
154 		NGM_PATCH_GETCLR_STATS,
155 		"getclrstats",
156 		NULL,
157 		&ng_patch_stats_type
158 	},
159 	{ 0 }
160 };
161 
162 static struct ng_type typestruct = {
163 	.version =	NG_ABI_VERSION,
164 	.name =		NG_PATCH_NODE_TYPE,
165 	.constructor =	ng_patch_constructor,
166 	.rcvmsg =	ng_patch_rcvmsg,
167 	.shutdown =	ng_patch_shutdown,
168 	.newhook =	ng_patch_newhook,
169 	.rcvdata =	ng_patch_rcvdata,
170 	.disconnect =	ng_patch_disconnect,
171 	.cmdlist =	ng_patch_cmdlist,
172 };
173 
174 NETGRAPH_INIT(patch, &typestruct);
175 
176 static int
177 ng_patch_constructor(node_p node)
178 {
179 	priv_p privdata;
180 
181 	privdata = malloc(sizeof(*privdata), M_NETGRAPH, M_WAITOK | M_ZERO);
182 	privdata->dlt = DLT_RAW;
183 
184 	NG_NODE_SET_PRIVATE(node, privdata);
185 
186 	return (0);
187 }
188 
189 static int
190 ng_patch_newhook(node_p node, hook_p hook, const char *name)
191 {
192 	const priv_p privp = NG_NODE_PRIVATE(node);
193 
194 	if (strncmp(name, NG_PATCH_HOOK_IN, strlen(NG_PATCH_HOOK_IN)) == 0) {
195 		privp->in = hook;
196 	} else if (strncmp(name, NG_PATCH_HOOK_OUT,
197 	    strlen(NG_PATCH_HOOK_OUT)) == 0) {
198 		privp->out = hook;
199 	} else
200 		return (EINVAL);
201 
202 	return (0);
203 }
204 
205 static int
206 ng_patch_rcvmsg(node_p node, item_p item, hook_p lasthook)
207 {
208 	const priv_p privp = NG_NODE_PRIVATE(node);
209 	struct ng_patch_config *conf, *newconf;
210 	struct ng_mesg *msg;
211 	struct ng_mesg *resp = NULL;
212 	int i, error = 0;
213 
214 	NGI_GET_MSG(item, msg);
215 
216 	if  (msg->header.typecookie != NGM_PATCH_COOKIE)
217 		ERROUT(EINVAL);
218 
219 	switch (msg->header.cmd)
220 	{
221 		case NGM_PATCH_GETCONFIG:
222 			if (privp->conf == NULL)
223 				ERROUT(0);
224 
225 			NG_MKRESPONSE(resp, msg,
226 			    NG_PATCH_CONF_SIZE(privp->conf->count), M_WAITOK);
227 
228 			if (resp == NULL)
229 				ERROUT(ENOMEM);
230 
231 			bcopy(privp->conf, resp->data,
232 			    NG_PATCH_CONF_SIZE(privp->conf->count));
233 
234 			conf = (struct ng_patch_config *) resp->data;
235 
236 			for (i = 0; i < conf->count; i++) {
237 				switch (conf->ops[i].length)
238 				{
239 					case 1:
240 						conf->ops[i].val.v8 = conf->ops[i].val.v1;
241 						break;
242 					case 2:
243 						conf->ops[i].val.v8 = conf->ops[i].val.v2;
244 						break;
245 					case 4:
246 						conf->ops[i].val.v8 = conf->ops[i].val.v4;
247 						break;
248 					case 8:
249 						break;
250 				}
251 			}
252 
253 			break;
254 
255 		case NGM_PATCH_SETCONFIG:
256 			conf = (struct ng_patch_config *) msg->data;
257 
258 			if (msg->header.arglen < sizeof(struct ng_patch_config) ||
259 			    msg->header.arglen < NG_PATCH_CONF_SIZE(conf->count))
260 				ERROUT(EINVAL);
261 
262 			for (i = 0; i < conf->count; i++) {
263 				switch (conf->ops[i].length)
264 				{
265 					case 1:
266 						conf->ops[i].val.v1 = (uint8_t) conf->ops[i].val.v8;
267 						break;
268 					case 2:
269 						conf->ops[i].val.v2 = (uint16_t) conf->ops[i].val.v8;
270 						break;
271 					case 4:
272 						conf->ops[i].val.v4 = (uint32_t) conf->ops[i].val.v8;
273 						break;
274 					case 8:
275 						break;
276 					default:
277 						ERROUT(EINVAL);
278 				}
279 			}
280 
281 			conf->csum_flags &= NG_PATCH_CSUM_IPV4|NG_PATCH_CSUM_IPV6;
282 			conf->relative_offset = !!conf->relative_offset;
283 
284 			newconf = malloc(NG_PATCH_CONF_SIZE(conf->count), M_NETGRAPH, M_WAITOK | M_ZERO);
285 
286 			bcopy(conf, newconf, NG_PATCH_CONF_SIZE(conf->count));
287 
288 			if (privp->conf)
289 				free(privp->conf, M_NETGRAPH);
290 
291 			privp->conf = newconf;
292 
293 			break;
294 
295 		case NGM_PATCH_GET_STATS:
296 		case NGM_PATCH_CLR_STATS:
297 		case NGM_PATCH_GETCLR_STATS:
298 			if (msg->header.cmd != NGM_PATCH_CLR_STATS) {
299 				NG_MKRESPONSE(resp, msg, sizeof(struct ng_patch_stats), M_WAITOK);
300 
301 				if (resp == NULL)
302 					ERROUT(ENOMEM);
303 
304 				bcopy(&(privp->stats), resp->data, sizeof(struct ng_patch_stats));
305 			}
306 
307 			if (msg->header.cmd != NGM_PATCH_GET_STATS)
308 				bzero(&(privp->stats), sizeof(struct ng_patch_stats));
309 
310 			break;
311 
312 		case NGM_PATCH_GETDLT:
313 			NG_MKRESPONSE(resp, msg, sizeof(uint8_t), M_WAITOK);
314 
315 			if (resp == NULL)
316 				ERROUT(ENOMEM);
317 
318 			*((uint8_t *) resp->data) = privp->dlt;
319 
320 			break;
321 
322 		case NGM_PATCH_SETDLT:
323 			if (msg->header.arglen != sizeof(uint8_t))
324 				ERROUT(EINVAL);
325 
326 			switch (*(uint8_t *) msg->data)
327 			{
328 				case DLT_EN10MB:
329 				case DLT_RAW:
330 					privp->dlt = *(uint8_t *) msg->data;
331 					break;
332 
333 				default:
334 					ERROUT(EINVAL);
335 			}
336 
337 			break;
338 
339 		default:
340 			ERROUT(EINVAL);
341 	}
342 
343 done:
344 	NG_RESPOND_MSG(error, node, item, resp);
345 	NG_FREE_MSG(msg);
346 
347 	return (error);
348 }
349 
350 static void
351 do_patch(priv_p privp, struct mbuf *m, int global_offset)
352 {
353 	int i, offset, patched = 0;
354 	union ng_patch_op_val val;
355 
356 	for (i = 0; i < privp->conf->count; i++) {
357 		offset = global_offset + privp->conf->ops[i].offset;
358 
359 		if (offset + privp->conf->ops[i].length > m->m_pkthdr.len)
360 			continue;
361 
362 		/* for "=" operation we don't need to copy data from mbuf */
363 		if (privp->conf->ops[i].mode != NG_PATCH_MODE_SET)
364 			m_copydata(m, offset, privp->conf->ops[i].length, (caddr_t) &val);
365 
366 		switch (privp->conf->ops[i].length)
367 		{
368 			case 1:
369 				switch (privp->conf->ops[i].mode)
370 				{
371 					case NG_PATCH_MODE_SET:
372 						val.v1 = privp->conf->ops[i].val.v1;
373 						break;
374 					case NG_PATCH_MODE_ADD:
375 						val.v1 += privp->conf->ops[i].val.v1;
376 						break;
377 					case NG_PATCH_MODE_SUB:
378 						val.v1 -= privp->conf->ops[i].val.v1;
379 						break;
380 					case NG_PATCH_MODE_MUL:
381 						val.v1 *= privp->conf->ops[i].val.v1;
382 						break;
383 					case NG_PATCH_MODE_DIV:
384 						val.v1 /= privp->conf->ops[i].val.v1;
385 						break;
386 					case NG_PATCH_MODE_NEG:
387 						*((int8_t *) &val) = - *((int8_t *) &val);
388 						break;
389 					case NG_PATCH_MODE_AND:
390 						val.v1 &= privp->conf->ops[i].val.v1;
391 						break;
392 					case NG_PATCH_MODE_OR:
393 						val.v1 |= privp->conf->ops[i].val.v1;
394 						break;
395 					case NG_PATCH_MODE_XOR:
396 						val.v1 ^= privp->conf->ops[i].val.v1;
397 						break;
398 					case NG_PATCH_MODE_SHL:
399 						val.v1 <<= privp->conf->ops[i].val.v1;
400 						break;
401 					case NG_PATCH_MODE_SHR:
402 						val.v1 >>= privp->conf->ops[i].val.v1;
403 						break;
404 				}
405 				break;
406 
407 			case 2:
408 				val.v2 = ntohs(val.v2);
409 
410 				switch (privp->conf->ops[i].mode)
411 				{
412 					case NG_PATCH_MODE_SET:
413 						val.v2 = privp->conf->ops[i].val.v2;
414 						break;
415 					case NG_PATCH_MODE_ADD:
416 						val.v2 += privp->conf->ops[i].val.v2;
417 						break;
418 					case NG_PATCH_MODE_SUB:
419 						val.v2 -= privp->conf->ops[i].val.v2;
420 						break;
421 					case NG_PATCH_MODE_MUL:
422 						val.v2 *= privp->conf->ops[i].val.v2;
423 						break;
424 					case NG_PATCH_MODE_DIV:
425 						val.v2 /= privp->conf->ops[i].val.v2;
426 						break;
427 					case NG_PATCH_MODE_NEG:
428 						*((int16_t *) &val) = - *((int16_t *) &val);
429 						break;
430 					case NG_PATCH_MODE_AND:
431 						val.v2 &= privp->conf->ops[i].val.v2;
432 						break;
433 					case NG_PATCH_MODE_OR:
434 						val.v2 |= privp->conf->ops[i].val.v2;
435 						break;
436 					case NG_PATCH_MODE_XOR:
437 						val.v2 ^= privp->conf->ops[i].val.v2;
438 						break;
439 					case NG_PATCH_MODE_SHL:
440 						val.v2 <<= privp->conf->ops[i].val.v2;
441 						break;
442 					case NG_PATCH_MODE_SHR:
443 						val.v2 >>= privp->conf->ops[i].val.v2;
444 						break;
445 				}
446 
447 				val.v2 = htons(val.v2);
448 
449 				break;
450 
451 			case 4:
452 				val.v4 = ntohl(val.v4);
453 
454 				switch (privp->conf->ops[i].mode)
455 				{
456 					case NG_PATCH_MODE_SET:
457 						val.v4 = privp->conf->ops[i].val.v4;
458 						break;
459 					case NG_PATCH_MODE_ADD:
460 						val.v4 += privp->conf->ops[i].val.v4;
461 						break;
462 					case NG_PATCH_MODE_SUB:
463 						val.v4 -= privp->conf->ops[i].val.v4;
464 						break;
465 					case NG_PATCH_MODE_MUL:
466 						val.v4 *= privp->conf->ops[i].val.v4;
467 						break;
468 					case NG_PATCH_MODE_DIV:
469 						val.v4 /= privp->conf->ops[i].val.v4;
470 						break;
471 					case NG_PATCH_MODE_NEG:
472 						*((int32_t *) &val) = - *((int32_t *) &val);
473 						break;
474 					case NG_PATCH_MODE_AND:
475 						val.v4 &= privp->conf->ops[i].val.v4;
476 						break;
477 					case NG_PATCH_MODE_OR:
478 						val.v4 |= privp->conf->ops[i].val.v4;
479 						break;
480 					case NG_PATCH_MODE_XOR:
481 						val.v4 ^= privp->conf->ops[i].val.v4;
482 						break;
483 					case NG_PATCH_MODE_SHL:
484 						val.v4 <<= privp->conf->ops[i].val.v4;
485 						break;
486 					case NG_PATCH_MODE_SHR:
487 						val.v4 >>= privp->conf->ops[i].val.v4;
488 						break;
489 				}
490 
491 				val.v4 = htonl(val.v4);
492 
493 				break;
494 
495 			case 8:
496 				val.v8 = be64toh(val.v8);
497 
498 				switch (privp->conf->ops[i].mode)
499 				{
500 					case NG_PATCH_MODE_SET:
501 						val.v8 = privp->conf->ops[i].val.v8;
502 						break;
503 					case NG_PATCH_MODE_ADD:
504 						val.v8 += privp->conf->ops[i].val.v8;
505 						break;
506 					case NG_PATCH_MODE_SUB:
507 						val.v8 -= privp->conf->ops[i].val.v8;
508 						break;
509 					case NG_PATCH_MODE_MUL:
510 						val.v8 *= privp->conf->ops[i].val.v8;
511 						break;
512 					case NG_PATCH_MODE_DIV:
513 						val.v8 /= privp->conf->ops[i].val.v8;
514 						break;
515 					case NG_PATCH_MODE_NEG:
516 						*((int64_t *) &val) = - *((int64_t *) &val);
517 						break;
518 					case NG_PATCH_MODE_AND:
519 						val.v8 &= privp->conf->ops[i].val.v8;
520 						break;
521 					case NG_PATCH_MODE_OR:
522 						val.v8 |= privp->conf->ops[i].val.v8;
523 						break;
524 					case NG_PATCH_MODE_XOR:
525 						val.v8 ^= privp->conf->ops[i].val.v8;
526 						break;
527 					case NG_PATCH_MODE_SHL:
528 						val.v8 <<= privp->conf->ops[i].val.v8;
529 						break;
530 					case NG_PATCH_MODE_SHR:
531 						val.v8 >>= privp->conf->ops[i].val.v8;
532 						break;
533 				}
534 
535 				val.v8 = htobe64(val.v8);
536 
537 				break;
538 		}
539 
540 		m_copyback(m, offset, privp->conf->ops[i].length, (caddr_t) &val);
541 		patched = 1;
542 	}
543 
544 	if (patched)
545 		privp->stats.patched++;
546 }
547 
548 static int
549 ng_patch_rcvdata(hook_p hook, item_p item)
550 {
551 	const priv_p priv = NG_NODE_PRIVATE(NG_HOOK_NODE(hook));
552 	struct mbuf *m;
553 	hook_p out;
554 	int pullup_len = 0;
555 	int error = 0;
556 
557 	priv->stats.received++;
558 
559 	NGI_GET_M(item, m);
560 
561 #define	PULLUP_CHECK(mbuf, length) do {					\
562 	pullup_len += length;						\
563 	if (((mbuf)->m_pkthdr.len < pullup_len) ||			\
564 	    (pullup_len > MHLEN)) {					\
565 		error = EINVAL;						\
566 		goto bypass;						\
567 	}								\
568 	if ((mbuf)->m_len < pullup_len &&				\
569 	    (((mbuf) = m_pullup((mbuf), pullup_len)) == NULL)) {	\
570 		error = ENOBUFS;					\
571 		goto drop;						\
572 	}								\
573 } while (0)
574 
575 	if (priv->conf && hook == priv->in &&
576 	    m && (m->m_flags & M_PKTHDR)) {
577 		m = m_unshare(m, M_NOWAIT);
578 
579 		if (m == NULL)
580 			ERROUT(ENOMEM);
581 
582 		if (priv->conf->relative_offset) {
583 			struct ether_header *eh;
584 			struct ng_patch_vlan_header *vh;
585 			uint16_t etype;
586 
587 			switch (priv->dlt)
588 			{
589 				case DLT_EN10MB:
590 					PULLUP_CHECK(m, sizeof(struct ether_header));
591 					eh = mtod(m, struct ether_header *);
592 					etype = ntohs(eh->ether_type);
593 
594 					for (;;) {	/* QinQ support */
595 						switch (etype)
596 						{
597 							case 0x8100:
598 							case 0x88A8:
599 							case 0x9100:
600 								PULLUP_CHECK(m, sizeof(struct ng_patch_vlan_header));
601 								vh = (struct ng_patch_vlan_header *) mtodo(m,
602 								    pullup_len - sizeof(struct ng_patch_vlan_header));
603 								etype = ntohs(vh->etype);
604 								break;
605 
606 							default:
607 								goto loopend;
608 						}
609 					}
610 loopend:
611 					break;
612 
613 				case DLT_RAW:
614 					break;
615 
616 				default:
617 					ERROUT(EINVAL);
618 			}
619 		}
620 
621 		do_patch(priv, m, pullup_len);
622 
623 		m->m_pkthdr.csum_flags |= priv->conf->csum_flags;
624 	}
625 
626 #undef	PULLUP_CHECK
627 
628 bypass:
629 	out = NULL;
630 
631 	if (hook == priv->in) {
632 		/* return frames on 'in' hook if 'out' not connected */
633 		out = priv->out ? priv->out : priv->in;
634 	} else if (hook == priv->out && priv->in) {
635 		/* pass frames on 'out' hook if 'in' connected */
636 		out = priv->in;
637 	}
638 
639 	if (out == NULL)
640 		ERROUT(0);
641 
642 	NG_FWD_NEW_DATA(error, item, out, m);
643 
644 	return (error);
645 
646 done:
647 drop:
648 	NG_FREE_ITEM(item);
649 	NG_FREE_M(m);
650 
651 	priv->stats.dropped++;
652 
653 	return (error);
654 }
655 
656 static int
657 ng_patch_shutdown(node_p node)
658 {
659 	const priv_p privdata = NG_NODE_PRIVATE(node);
660 
661 	NG_NODE_SET_PRIVATE(node, NULL);
662 	NG_NODE_UNREF(node);
663 
664 	if (privdata->conf != NULL)
665 		free(privdata->conf, M_NETGRAPH);
666 
667 	free(privdata, M_NETGRAPH);
668 
669 	return (0);
670 }
671 
672 static int
673 ng_patch_disconnect(hook_p hook)
674 {
675 	priv_p priv;
676 
677 	priv = NG_NODE_PRIVATE(NG_HOOK_NODE(hook));
678 
679 	if (hook == priv->in) {
680 		priv->in = NULL;
681 	}
682 
683 	if (hook == priv->out) {
684 		priv->out = NULL;
685 	}
686 
687 	if (NG_NODE_NUMHOOKS(NG_HOOK_NODE(hook)) == 0 &&
688 	    NG_NODE_IS_VALID(NG_HOOK_NODE(hook))) /* already shutting down? */
689 		ng_rmnode_self(NG_HOOK_NODE(hook));
690 
691 	return (0);
692 }
693