xref: /freebsd/sys/netipsec/ipsec_input.c (revision d7d962ead0b6e5e8a39202d0590022082bf5bfb6)
1 /*	$OpenBSD: ipsec_input.c,v 1.63 2003/02/20 18:35:43 deraadt Exp $	*/
2 /*-
3  * The authors of this code are John Ioannidis (ji@tla.org),
4  * Angelos D. Keromytis (kermit@csd.uch.gr) and
5  * Niels Provos (provos@physnet.uni-hamburg.de).
6  *
7  * This code was written by John Ioannidis for BSD/OS in Athens, Greece,
8  * in November 1995.
9  *
10  * Ported to OpenBSD and NetBSD, with additional transforms, in December 1996,
11  * by Angelos D. Keromytis.
12  *
13  * Additional transforms and features in 1997 and 1998 by Angelos D. Keromytis
14  * and Niels Provos.
15  *
16  * Additional features in 1999 by Angelos D. Keromytis.
17  *
18  * Copyright (C) 1995, 1996, 1997, 1998, 1999 by John Ioannidis,
19  * Angelos D. Keromytis and Niels Provos.
20  * Copyright (c) 2001, Angelos D. Keromytis.
21  * Copyright (c) 2016 Andrey V. Elsukov <ae@FreeBSD.org>
22  *
23  * Permission to use, copy, and modify this software with or without fee
24  * is hereby granted, provided that this entire notice is included in
25  * all copies of any software which is or includes a copy or
26  * modification of this software.
27  * You may use this code under the GNU public license if you so wish. Please
28  * contribute changes back to the authors under this freer than GPL license
29  * so that we may further the use of strong encryption without limitations to
30  * all.
31  *
32  * THIS SOFTWARE IS BEING PROVIDED "AS IS", WITHOUT ANY EXPRESS OR
33  * IMPLIED WARRANTY. IN PARTICULAR, NONE OF THE AUTHORS MAKES ANY
34  * REPRESENTATION OR WARRANTY OF ANY KIND CONCERNING THE
35  * MERCHANTABILITY OF THIS SOFTWARE OR ITS FITNESS FOR ANY PARTICULAR
36  * PURPOSE.
37  */
38 
39 /*
40  * IPsec input processing.
41  */
42 
43 #include <sys/cdefs.h>
44 __FBSDID("$FreeBSD$");
45 
46 #include "opt_inet.h"
47 #include "opt_inet6.h"
48 #include "opt_ipsec.h"
49 
50 #include <sys/param.h>
51 #include <sys/systm.h>
52 #include <sys/malloc.h>
53 #include <sys/mbuf.h>
54 #include <sys/domain.h>
55 #include <sys/protosw.h>
56 #include <sys/socket.h>
57 #include <sys/errno.h>
58 #include <sys/hhook.h>
59 #include <sys/syslog.h>
60 
61 #include <net/if.h>
62 #include <net/if_var.h>
63 #include <net/if_enc.h>
64 #include <net/netisr.h>
65 #include <net/vnet.h>
66 
67 #include <netinet/in.h>
68 #include <netinet/in_systm.h>
69 #include <netinet/ip.h>
70 #include <netinet/ip_var.h>
71 #include <netinet/ip_icmp.h>
72 #include <netinet/in_var.h>
73 #include <netinet/tcp_var.h>
74 
75 #include <netinet/ip6.h>
76 #ifdef INET6
77 #include <netinet6/ip6_var.h>
78 #endif
79 #include <netinet/in_pcb.h>
80 #ifdef INET6
81 #include <netinet/icmp6.h>
82 #endif
83 
84 #include <netipsec/ipsec.h>
85 #ifdef INET6
86 #include <netipsec/ipsec6.h>
87 #endif
88 #include <netipsec/ah_var.h>
89 #include <netipsec/esp.h>
90 #include <netipsec/esp_var.h>
91 #include <netipsec/ipcomp_var.h>
92 
93 #include <netipsec/key.h>
94 #include <netipsec/keydb.h>
95 #include <netipsec/key_debug.h>
96 
97 #include <netipsec/xform.h>
98 #include <netinet6/ip6protosw.h>
99 
100 #include <machine/in_cksum.h>
101 #include <machine/stdarg.h>
102 
103 #define	IPSEC_ISTAT(proto, name)	do {	\
104 	if ((proto) == IPPROTO_ESP)		\
105 		ESPSTAT_INC(esps_##name);	\
106 	else if ((proto) == IPPROTO_AH)		\
107 		AHSTAT_INC(ahs_##name);		\
108 	else					\
109 		IPCOMPSTAT_INC(ipcomps_##name);	\
110 } while (0)
111 
112 /*
113  * ipsec_common_input gets called when an IPsec-protected packet
114  * is received by IPv4 or IPv6.  Its job is to find the right SA
115  * and call the appropriate transform.  The transform callback
116  * takes care of further processing (like ingress filtering).
117  */
118 static int
119 ipsec_common_input(struct mbuf *m, int skip, int protoff, int af, int sproto)
120 {
121 	IPSEC_DEBUG_DECLARE(char buf[IPSEC_ADDRSTRLEN]);
122 	union sockaddr_union dst_address;
123 	struct secasvar *sav;
124 	uint32_t spi;
125 	int error;
126 
127 	IPSEC_ISTAT(sproto, input);
128 
129 	IPSEC_ASSERT(m != NULL, ("null packet"));
130 
131 	IPSEC_ASSERT(sproto == IPPROTO_ESP || sproto == IPPROTO_AH ||
132 		sproto == IPPROTO_IPCOMP,
133 		("unexpected security protocol %u", sproto));
134 
135 	if ((sproto == IPPROTO_ESP && !V_esp_enable) ||
136 	    (sproto == IPPROTO_AH && !V_ah_enable) ||
137 	    (sproto == IPPROTO_IPCOMP && !V_ipcomp_enable)) {
138 		m_freem(m);
139 		IPSEC_ISTAT(sproto, pdrops);
140 		return EOPNOTSUPP;
141 	}
142 
143 	if (m->m_pkthdr.len - skip < 2 * sizeof (u_int32_t)) {
144 		m_freem(m);
145 		IPSEC_ISTAT(sproto, hdrops);
146 		DPRINTF(("%s: packet too small\n", __func__));
147 		return EINVAL;
148 	}
149 
150 	/* Retrieve the SPI from the relevant IPsec header */
151 	if (sproto == IPPROTO_ESP)
152 		m_copydata(m, skip, sizeof(u_int32_t), (caddr_t) &spi);
153 	else if (sproto == IPPROTO_AH)
154 		m_copydata(m, skip + sizeof(u_int32_t), sizeof(u_int32_t),
155 		    (caddr_t) &spi);
156 	else if (sproto == IPPROTO_IPCOMP) {
157 		u_int16_t cpi;
158 		m_copydata(m, skip + sizeof(u_int16_t), sizeof(u_int16_t),
159 		    (caddr_t) &cpi);
160 		spi = ntohl(htons(cpi));
161 	}
162 
163 	/*
164 	 * Find the SA and (indirectly) call the appropriate
165 	 * kernel crypto routine. The resulting mbuf chain is a valid
166 	 * IP packet ready to go through input processing.
167 	 */
168 	bzero(&dst_address, sizeof (dst_address));
169 	dst_address.sa.sa_family = af;
170 	switch (af) {
171 #ifdef INET
172 	case AF_INET:
173 		dst_address.sin.sin_len = sizeof(struct sockaddr_in);
174 		m_copydata(m, offsetof(struct ip, ip_dst),
175 		    sizeof(struct in_addr),
176 		    (caddr_t) &dst_address.sin.sin_addr);
177 		break;
178 #endif /* INET */
179 #ifdef INET6
180 	case AF_INET6:
181 		dst_address.sin6.sin6_len = sizeof(struct sockaddr_in6);
182 		m_copydata(m, offsetof(struct ip6_hdr, ip6_dst),
183 		    sizeof(struct in6_addr),
184 		    (caddr_t) &dst_address.sin6.sin6_addr);
185 		/* We keep addresses in SADB without embedded scope id */
186 		if (IN6_IS_SCOPE_LINKLOCAL(&dst_address.sin6.sin6_addr)) {
187 			/* XXX: sa6_recoverscope() */
188 			dst_address.sin6.sin6_scope_id =
189 			    ntohs(dst_address.sin6.sin6_addr.s6_addr16[1]);
190 			dst_address.sin6.sin6_addr.s6_addr16[1] = 0;
191 		}
192 		break;
193 #endif /* INET6 */
194 	default:
195 		DPRINTF(("%s: unsupported protocol family %u\n", __func__, af));
196 		m_freem(m);
197 		IPSEC_ISTAT(sproto, nopf);
198 		return EPFNOSUPPORT;
199 	}
200 
201 	/* NB: only pass dst since key_allocsa follows RFC2401 */
202 	sav = key_allocsa(&dst_address, sproto, spi);
203 	if (sav == NULL) {
204 		DPRINTF(("%s: no key association found for SA %s/%08lx/%u\n",
205 		    __func__, ipsec_address(&dst_address, buf, sizeof(buf)),
206 		    (u_long) ntohl(spi), sproto));
207 		IPSEC_ISTAT(sproto, notdb);
208 		m_freem(m);
209 		return ENOENT;
210 	}
211 
212 	if (sav->tdb_xform == NULL) {
213 		DPRINTF(("%s: attempted to use uninitialized SA %s/%08lx/%u\n",
214 		    __func__, ipsec_address(&dst_address, buf, sizeof(buf)),
215 		    (u_long) ntohl(spi), sproto));
216 		IPSEC_ISTAT(sproto, noxform);
217 		key_freesav(&sav);
218 		m_freem(m);
219 		return ENXIO;
220 	}
221 
222 	/*
223 	 * Call appropriate transform and return -- callback takes care of
224 	 * everything else.
225 	 */
226 	error = (*sav->tdb_xform->xf_input)(m, sav, skip, protoff);
227 	return (error);
228 }
229 
230 #ifdef INET
231 extern struct protosw inetsw[];
232 
233 /*
234  * IPSEC_INPUT() method implementation for IPv4.
235  *  0 - Permitted by inbound security policy for further processing.
236  *  EACCES - Forbidden by inbound security policy.
237  *  EINPROGRESS - consumed by IPsec.
238  */
239 int
240 ipsec4_input(struct mbuf *m, int offset, int proto)
241 {
242 
243 	switch (proto) {
244 	case IPPROTO_AH:
245 	case IPPROTO_ESP:
246 	case IPPROTO_IPCOMP:
247 		/* Do inbound IPsec processing for AH/ESP/IPCOMP */
248 		ipsec_common_input(m, offset,
249 		    offsetof(struct ip, ip_p), AF_INET, proto);
250 		return (EINPROGRESS); /* mbuf consumed by IPsec */
251 	default:
252 		/*
253 		 * Protocols with further headers get their IPsec treatment
254 		 * within the protocol specific processing.
255 		 */
256 		if ((inetsw[ip_protox[proto]].pr_flags & PR_LASTHDR) == 0)
257 			return (0);
258 		/* FALLTHROUGH */
259 	};
260 	/*
261 	 * Enforce IPsec policy checking if we are seeing last header.
262 	 */
263 	if (ipsec4_in_reject(m, NULL) != 0) {
264 		/* Forbidden by inbound security policy */
265 		m_freem(m);
266 		return (EACCES);
267 	}
268 	return (0);
269 }
270 
271 int
272 ipsec4_ctlinput(int code, struct sockaddr *sa, void *v)
273 {
274 	struct in_conninfo inc;
275 	struct secasvar *sav;
276 	struct icmp *icp;
277 	struct ip *ip = v;
278 	uint32_t pmtu, spi;
279 	uint8_t proto;
280 
281 	if (code != PRC_MSGSIZE || ip == NULL)
282 		return (EINVAL);
283 	if (sa->sa_family != AF_INET ||
284 	    sa->sa_len != sizeof(struct sockaddr_in))
285 		return (EAFNOSUPPORT);
286 
287 	icp = __containerof(ip, struct icmp, icmp_ip);
288 	pmtu = ntohs(icp->icmp_nextmtu);
289 
290 	if (pmtu < V_ip4_ipsec_min_pmtu)
291 		return (EINVAL);
292 
293 	proto = ip->ip_p;
294 	if (proto != IPPROTO_ESP && proto != IPPROTO_AH &&
295 	    proto != IPPROTO_IPCOMP)
296 		return (EINVAL);
297 
298 	memcpy(&spi, (caddr_t)ip + (ip->ip_hl << 2), sizeof(spi));
299 	sav = key_allocsa((union sockaddr_union *)sa, proto, spi);
300 	if (sav == NULL)
301 		return (ENOENT);
302 
303 	key_freesav(&sav);
304 
305 	memset(&inc, 0, sizeof(inc));
306 	inc.inc_faddr = satosin(sa)->sin_addr;
307 	tcp_hc_updatemtu(&inc, pmtu);
308 	return (0);
309 }
310 
311 /*
312  * IPsec input callback for INET protocols.
313  * This routine is called as the transform callback.
314  * Takes care of filtering and other sanity checks on
315  * the processed packet.
316  */
317 int
318 ipsec4_common_input_cb(struct mbuf *m, struct secasvar *sav, int skip,
319     int protoff)
320 {
321 	IPSEC_DEBUG_DECLARE(char buf[IPSEC_ADDRSTRLEN]);
322 	struct epoch_tracker et;
323 	struct ipsec_ctx_data ctx;
324 	struct xform_history *xh;
325 	struct secasindex *saidx;
326 	struct m_tag *mtag;
327 	struct ip *ip;
328 	int error, prot, af, sproto, isr_prot;
329 
330 	IPSEC_ASSERT(sav != NULL, ("null SA"));
331 	IPSEC_ASSERT(sav->sah != NULL, ("null SAH"));
332 	saidx = &sav->sah->saidx;
333 	af = saidx->dst.sa.sa_family;
334 	IPSEC_ASSERT(af == AF_INET, ("unexpected af %u", af));
335 	sproto = saidx->proto;
336 	IPSEC_ASSERT(sproto == IPPROTO_ESP || sproto == IPPROTO_AH ||
337 		sproto == IPPROTO_IPCOMP,
338 		("unexpected security protocol %u", sproto));
339 
340 	if (skip != 0) {
341 		/*
342 		 * Fix IPv4 header
343 		 */
344 		if (m->m_len < skip && (m = m_pullup(m, skip)) == NULL) {
345 			DPRINTF(("%s: processing failed for SA %s/%08lx\n",
346 			    __func__, ipsec_address(&sav->sah->saidx.dst,
347 			    buf, sizeof(buf)), (u_long) ntohl(sav->spi)));
348 			IPSEC_ISTAT(sproto, hdrops);
349 			error = ENOBUFS;
350 			goto bad;
351 		}
352 
353 		ip = mtod(m, struct ip *);
354 		ip->ip_len = htons(m->m_pkthdr.len);
355 		ip->ip_sum = 0;
356 		ip->ip_sum = in_cksum(m, ip->ip_hl << 2);
357 	} else {
358 		ip = mtod(m, struct ip *);
359 	}
360 	prot = ip->ip_p;
361 	/*
362 	 * Check that we have NAT-T enabled and apply transport mode
363 	 * decapsulation NAT procedure (RFC3948).
364 	 * Do this before invoking into the PFIL.
365 	 */
366 	if (sav->natt != NULL &&
367 	    (prot == IPPROTO_UDP || prot == IPPROTO_TCP))
368 		udp_ipsec_adjust_cksum(m, sav, prot, skip);
369 
370 	IPSEC_INIT_CTX(&ctx, &m, NULL, sav, AF_INET, IPSEC_ENC_BEFORE);
371 	if ((error = ipsec_run_hhooks(&ctx, HHOOK_TYPE_IPSEC_IN)) != 0)
372 		goto bad;
373 	ip = mtod(m, struct ip *);	/* update pointer */
374 
375 	/* IP-in-IP encapsulation */
376 	if (prot == IPPROTO_IPIP &&
377 	    saidx->mode != IPSEC_MODE_TRANSPORT) {
378 		if (m->m_pkthdr.len - skip < sizeof(struct ip)) {
379 			IPSEC_ISTAT(sproto, hdrops);
380 			error = EINVAL;
381 			goto bad;
382 		}
383 		/* enc0: strip outer IPv4 header */
384 		m_striphdr(m, 0, ip->ip_hl << 2);
385 	}
386 #ifdef INET6
387 	/* IPv6-in-IP encapsulation. */
388 	else if (prot == IPPROTO_IPV6 &&
389 	    saidx->mode != IPSEC_MODE_TRANSPORT) {
390 		if (m->m_pkthdr.len - skip < sizeof(struct ip6_hdr)) {
391 			IPSEC_ISTAT(sproto, hdrops);
392 			error = EINVAL;
393 			goto bad;
394 		}
395 		/* enc0: strip IPv4 header, keep IPv6 header only */
396 		m_striphdr(m, 0, ip->ip_hl << 2);
397 	}
398 #endif /* INET6 */
399 	else if (prot != IPPROTO_IPV6 && saidx->mode == IPSEC_MODE_ANY) {
400 		/*
401 		 * When mode is wildcard, inner protocol is IPv6 and
402 		 * we have no INET6 support - drop this packet a bit later.
403 		 * In other cases we assume transport mode. Set prot to
404 		 * correctly choose netisr.
405 		 */
406 		prot = IPPROTO_IPIP;
407 	}
408 
409 	/*
410 	 * Record what we've done to the packet (under what SA it was
411 	 * processed).
412 	 */
413 	if (sproto != IPPROTO_IPCOMP) {
414 		mtag = m_tag_get(PACKET_TAG_IPSEC_IN_DONE,
415 		    sizeof(struct xform_history), M_NOWAIT);
416 		if (mtag == NULL) {
417 			DPRINTF(("%s: failed to get tag\n", __func__));
418 			IPSEC_ISTAT(sproto, hdrops);
419 			error = ENOMEM;
420 			goto bad;
421 		}
422 
423 		xh = (struct xform_history *)(mtag + 1);
424 		bcopy(&saidx->dst, &xh->dst, saidx->dst.sa.sa_len);
425 		xh->spi = sav->spi;
426 		xh->proto = sproto;
427 		xh->mode = saidx->mode;
428 		m_tag_prepend(m, mtag);
429 	}
430 
431 	key_sa_recordxfer(sav, m);		/* record data transfer */
432 
433 	/*
434 	 * In transport mode requeue decrypted mbuf back to IPv4 protocol
435 	 * handler. This is necessary to correctly expose rcvif.
436 	 */
437 	if (saidx->mode == IPSEC_MODE_TRANSPORT)
438 		prot = IPPROTO_IPIP;
439 	/*
440 	 * Re-dispatch via software interrupt.
441 	 */
442 	switch (prot) {
443 	case IPPROTO_IPIP:
444 		isr_prot = NETISR_IP;
445 		af = AF_INET;
446 		break;
447 #ifdef INET6
448 	case IPPROTO_IPV6:
449 		isr_prot = NETISR_IPV6;
450 		af = AF_INET6;
451 		break;
452 #endif
453 	default:
454 		DPRINTF(("%s: cannot handle inner ip proto %d\n",
455 			    __func__, prot));
456 		IPSEC_ISTAT(sproto, nopf);
457 		error = EPFNOSUPPORT;
458 		goto bad;
459 	}
460 
461 	IPSEC_INIT_CTX(&ctx, &m, NULL, sav, af, IPSEC_ENC_AFTER);
462 	if ((error = ipsec_run_hhooks(&ctx, HHOOK_TYPE_IPSEC_IN)) != 0)
463 		goto bad;
464 
465 	/* Handle virtual tunneling interfaces */
466 	if (saidx->mode == IPSEC_MODE_TUNNEL)
467 		error = ipsec_if_input(m, sav, af);
468 	if (error == 0) {
469 		NET_EPOCH_ENTER(et);
470 		error = netisr_queue_src(isr_prot, (uintptr_t)sav->spi, m);
471 		NET_EPOCH_EXIT(et);
472 		if (error) {
473 			IPSEC_ISTAT(sproto, qfull);
474 			DPRINTF(("%s: queue full; proto %u packet dropped\n",
475 			    __func__, sproto));
476 		}
477 	}
478 	key_freesav(&sav);
479 	return (error);
480 bad:
481 	key_freesav(&sav);
482 	if (m != NULL)
483 		m_freem(m);
484 	return (error);
485 }
486 #endif /* INET */
487 
488 #ifdef INET6
489 /*
490  * IPSEC_INPUT() method implementation for IPv6.
491  *  0 - Permitted by inbound security policy for further processing.
492  *  EACCES - Forbidden by inbound security policy.
493  *  EINPROGRESS - consumed by IPsec.
494  */
495 int
496 ipsec6_input(struct mbuf *m, int offset, int proto)
497 {
498 
499 	switch (proto) {
500 	case IPPROTO_AH:
501 	case IPPROTO_ESP:
502 	case IPPROTO_IPCOMP:
503 		/* Do inbound IPsec processing for AH/ESP/IPCOMP */
504 		ipsec_common_input(m, offset,
505 		    offsetof(struct ip6_hdr, ip6_nxt), AF_INET6, proto);
506 		return (EINPROGRESS); /* mbuf consumed by IPsec */
507 	default:
508 		/*
509 		 * Protocols with further headers get their IPsec treatment
510 		 * within the protocol specific processing.
511 		 */
512 		if ((inet6sw[ip6_protox[proto]].pr_flags & PR_LASTHDR) == 0)
513 			return (0);
514 		/* FALLTHROUGH */
515 	};
516 	/*
517 	 * Enforce IPsec policy checking if we are seeing last header.
518 	 */
519 	if (ipsec6_in_reject(m, NULL) != 0) {
520 		/* Forbidden by inbound security policy */
521 		m_freem(m);
522 		return (EACCES);
523 	}
524 	return (0);
525 }
526 
527 int
528 ipsec6_ctlinput(int code, struct sockaddr *sa, void *v)
529 {
530 	return (0);
531 }
532 
533 /*
534  * IPsec input callback, called by the transform callback. Takes care of
535  * filtering and other sanity checks on the processed packet.
536  */
537 int
538 ipsec6_common_input_cb(struct mbuf *m, struct secasvar *sav, int skip,
539     int protoff)
540 {
541 	IPSEC_DEBUG_DECLARE(char buf[IPSEC_ADDRSTRLEN]);
542 	struct epoch_tracker et;
543 	struct ipsec_ctx_data ctx;
544 	struct xform_history *xh;
545 	struct secasindex *saidx;
546 	struct ip6_hdr *ip6;
547 	struct m_tag *mtag;
548 	int prot, af, sproto;
549 	int nxt, isr_prot;
550 	int error, nest;
551 	uint8_t nxt8;
552 
553 	IPSEC_ASSERT(sav != NULL, ("null SA"));
554 	IPSEC_ASSERT(sav->sah != NULL, ("null SAH"));
555 	saidx = &sav->sah->saidx;
556 	af = saidx->dst.sa.sa_family;
557 	IPSEC_ASSERT(af == AF_INET6, ("unexpected af %u", af));
558 	sproto = saidx->proto;
559 	IPSEC_ASSERT(sproto == IPPROTO_ESP || sproto == IPPROTO_AH ||
560 		sproto == IPPROTO_IPCOMP,
561 		("unexpected security protocol %u", sproto));
562 
563 	/* Fix IPv6 header */
564 	if (m->m_len < sizeof(struct ip6_hdr) &&
565 	    (m = m_pullup(m, sizeof(struct ip6_hdr))) == NULL) {
566 		DPRINTF(("%s: processing failed for SA %s/%08lx\n",
567 		    __func__, ipsec_address(&sav->sah->saidx.dst, buf,
568 		    sizeof(buf)), (u_long) ntohl(sav->spi)));
569 
570 		IPSEC_ISTAT(sproto, hdrops);
571 		error = EACCES;
572 		goto bad;
573 	}
574 
575 	IPSEC_INIT_CTX(&ctx, &m, NULL, sav, af, IPSEC_ENC_BEFORE);
576 	if ((error = ipsec_run_hhooks(&ctx, HHOOK_TYPE_IPSEC_IN)) != 0)
577 		goto bad;
578 
579 	ip6 = mtod(m, struct ip6_hdr *);
580 	ip6->ip6_plen = htons(m->m_pkthdr.len - sizeof(struct ip6_hdr));
581 
582 	/* Save protocol */
583 	m_copydata(m, protoff, 1, &nxt8);
584 	prot = nxt8;
585 
586 	/* IPv6-in-IP encapsulation */
587 	if (prot == IPPROTO_IPV6 &&
588 	    saidx->mode != IPSEC_MODE_TRANSPORT) {
589 		if (m->m_pkthdr.len - skip < sizeof(struct ip6_hdr)) {
590 			IPSEC_ISTAT(sproto, hdrops);
591 			error = EINVAL;
592 			goto bad;
593 		}
594 		/* ip6n will now contain the inner IPv6 header. */
595 		m_striphdr(m, 0, skip);
596 		skip = 0;
597 	}
598 #ifdef INET
599 	/* IP-in-IP encapsulation */
600 	else if (prot == IPPROTO_IPIP &&
601 	    saidx->mode != IPSEC_MODE_TRANSPORT) {
602 		if (m->m_pkthdr.len - skip < sizeof(struct ip)) {
603 			IPSEC_ISTAT(sproto, hdrops);
604 			error = EINVAL;
605 			goto bad;
606 		}
607 		/* ipn will now contain the inner IPv4 header */
608 		m_striphdr(m, 0, skip);
609 		skip = 0;
610 	}
611 #endif /* INET */
612 	else {
613 		prot = IPPROTO_IPV6; /* for correct BPF processing */
614 	}
615 
616 	/*
617 	 * Record what we've done to the packet (under what SA it was
618 	 * processed).
619 	 */
620 	if (sproto != IPPROTO_IPCOMP) {
621 		mtag = m_tag_get(PACKET_TAG_IPSEC_IN_DONE,
622 		    sizeof(struct xform_history), M_NOWAIT);
623 		if (mtag == NULL) {
624 			DPRINTF(("%s: failed to get tag\n", __func__));
625 			IPSEC_ISTAT(sproto, hdrops);
626 			error = ENOMEM;
627 			goto bad;
628 		}
629 
630 		xh = (struct xform_history *)(mtag + 1);
631 		bcopy(&saidx->dst, &xh->dst, saidx->dst.sa.sa_len);
632 		xh->spi = sav->spi;
633 		xh->proto = sproto;
634 		xh->mode = saidx->mode;
635 		m_tag_prepend(m, mtag);
636 	}
637 
638 	key_sa_recordxfer(sav, m);
639 
640 #ifdef INET
641 	if (prot == IPPROTO_IPIP)
642 		af = AF_INET;
643 	else
644 #endif
645 		af = AF_INET6;
646 	IPSEC_INIT_CTX(&ctx, &m, NULL, sav, af, IPSEC_ENC_AFTER);
647 	if ((error = ipsec_run_hhooks(&ctx, HHOOK_TYPE_IPSEC_IN)) != 0)
648 		goto bad;
649 	if (skip == 0) {
650 		/*
651 		 * We stripped outer IPv6 header.
652 		 * Now we should requeue decrypted packet via netisr.
653 		 */
654 		switch (prot) {
655 #ifdef INET
656 		case IPPROTO_IPIP:
657 			isr_prot = NETISR_IP;
658 			break;
659 #endif
660 		case IPPROTO_IPV6:
661 			isr_prot = NETISR_IPV6;
662 			break;
663 		default:
664 			DPRINTF(("%s: cannot handle inner ip proto %d\n",
665 			    __func__, prot));
666 			IPSEC_ISTAT(sproto, nopf);
667 			error = EPFNOSUPPORT;
668 			goto bad;
669 		}
670 		/* Handle virtual tunneling interfaces */
671 		if (saidx->mode == IPSEC_MODE_TUNNEL)
672 			error = ipsec_if_input(m, sav, af);
673 		if (error == 0) {
674 			NET_EPOCH_ENTER(et);
675 			error = netisr_queue_src(isr_prot,
676 			    (uintptr_t)sav->spi, m);
677 			NET_EPOCH_EXIT(et);
678 			if (error) {
679 				IPSEC_ISTAT(sproto, qfull);
680 				DPRINTF(("%s: queue full; proto %u packet"
681 				    " dropped\n", __func__, sproto));
682 			}
683 		}
684 		key_freesav(&sav);
685 		return (error);
686 	}
687 	/*
688 	 * See the end of ip6_input for this logic.
689 	 * IPPROTO_IPV[46] case will be processed just like other ones
690 	 */
691 	nest = 0;
692 	nxt = nxt8;
693 	NET_EPOCH_ENTER(et);
694 	while (nxt != IPPROTO_DONE) {
695 		if (V_ip6_hdrnestlimit && (++nest > V_ip6_hdrnestlimit)) {
696 			IP6STAT_INC(ip6s_toomanyhdr);
697 			error = EINVAL;
698 			goto bad_epoch;
699 		}
700 
701 		/*
702 		 * Protection against faulty packet - there should be
703 		 * more sanity checks in header chain processing.
704 		 */
705 		if (m->m_pkthdr.len < skip) {
706 			IP6STAT_INC(ip6s_tooshort);
707 			in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_truncated);
708 			error = EINVAL;
709 			goto bad_epoch;
710 		}
711 		/*
712 		 * Enforce IPsec policy checking if we are seeing last header.
713 		 * note that we do not visit this with protocols with pcb layer
714 		 * code - like udp/tcp/raw ip.
715 		 */
716 		if ((inet6sw[ip6_protox[nxt]].pr_flags & PR_LASTHDR) != 0 &&
717 		    ipsec6_in_reject(m, NULL)) {
718 			error = EINVAL;
719 			goto bad_epoch;
720 		}
721 		nxt = (*inet6sw[ip6_protox[nxt]].pr_input)(&m, &skip, nxt);
722 	}
723 	NET_EPOCH_EXIT(et);
724 	key_freesav(&sav);
725 	return (0);
726 bad_epoch:
727 	NET_EPOCH_EXIT(et);
728 bad:
729 	key_freesav(&sav);
730 	if (m)
731 		m_freem(m);
732 	return (error);
733 }
734 #endif /* INET6 */
735