1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * xfrm_output.c - Common IPsec encapsulation code.
4 *
5 * Copyright (c) 2007 Herbert Xu <herbert@gondor.apana.org.au>
6 */
7
8 #include <linux/errno.h>
9 #include <linux/module.h>
10 #include <linux/netdevice.h>
11 #include <linux/netfilter.h>
12 #include <linux/skbuff.h>
13 #include <linux/slab.h>
14 #include <linux/spinlock.h>
15 #include <net/dst.h>
16 #include <net/inet_ecn.h>
17 #include <net/xfrm.h>
18
19 #include "xfrm_inout.h"
20
21 static int xfrm_output2(struct net *net, struct sock *sk, struct sk_buff *skb);
22 static int xfrm_inner_extract_output(struct xfrm_state *x, struct sk_buff *skb);
23
xfrm_skb_check_space(struct sk_buff * skb)24 static int xfrm_skb_check_space(struct sk_buff *skb)
25 {
26 struct dst_entry *dst = skb_dst(skb);
27 int nhead = dst->header_len + LL_RESERVED_SPACE(dst->dev)
28 - skb_headroom(skb);
29 int ntail = dst->dev->needed_tailroom - skb_tailroom(skb);
30
31 if (nhead <= 0) {
32 if (ntail <= 0)
33 return 0;
34 nhead = 0;
35 } else if (ntail < 0)
36 ntail = 0;
37
38 return pskb_expand_head(skb, nhead, ntail, GFP_ATOMIC);
39 }
40
41 /* Children define the path of the packet through the
42 * Linux networking. Thus, destinations are stackable.
43 */
44
skb_dst_pop(struct sk_buff * skb)45 static struct dst_entry *skb_dst_pop(struct sk_buff *skb)
46 {
47 struct dst_entry *child = dst_clone(xfrm_dst_child(skb_dst(skb)));
48
49 skb_dst_drop(skb);
50 return child;
51 }
52
53 /* Add encapsulation header.
54 *
55 * The IP header will be moved forward to make space for the encapsulation
56 * header.
57 */
xfrm4_transport_output(struct xfrm_state * x,struct sk_buff * skb)58 static int xfrm4_transport_output(struct xfrm_state *x, struct sk_buff *skb)
59 {
60 struct iphdr *iph = ip_hdr(skb);
61 int ihl = iph->ihl * 4;
62
63 skb_set_inner_transport_header(skb, skb_transport_offset(skb));
64
65 skb_set_network_header(skb, -x->props.header_len);
66 skb->mac_header = skb->network_header +
67 offsetof(struct iphdr, protocol);
68 skb->transport_header = skb->network_header + ihl;
69 __skb_pull(skb, ihl);
70 memmove(skb_network_header(skb), iph, ihl);
71 return 0;
72 }
73
74 /* Add encapsulation header.
75 *
76 * The IP header and mutable extension headers will be moved forward to make
77 * space for the encapsulation header.
78 */
xfrm6_transport_output(struct xfrm_state * x,struct sk_buff * skb)79 static int xfrm6_transport_output(struct xfrm_state *x, struct sk_buff *skb)
80 {
81 #if IS_ENABLED(CONFIG_IPV6)
82 struct ipv6hdr *iph;
83 u8 *prevhdr;
84 int hdr_len;
85
86 iph = ipv6_hdr(skb);
87 skb_set_inner_transport_header(skb, skb_transport_offset(skb));
88
89 hdr_len = x->type->hdr_offset(x, skb, &prevhdr);
90 if (hdr_len < 0)
91 return hdr_len;
92 skb_set_mac_header(skb,
93 (prevhdr - x->props.header_len) - skb->data);
94 skb_set_network_header(skb, -x->props.header_len);
95 skb->transport_header = skb->network_header + hdr_len;
96 __skb_pull(skb, hdr_len);
97 memmove(ipv6_hdr(skb), iph, hdr_len);
98 return 0;
99 #else
100 WARN_ON_ONCE(1);
101 return -EAFNOSUPPORT;
102 #endif
103 }
104
105 /* Add route optimization header space.
106 *
107 * The IP header and mutable extension headers will be moved forward to make
108 * space for the route optimization header.
109 */
xfrm6_ro_output(struct xfrm_state * x,struct sk_buff * skb)110 static int xfrm6_ro_output(struct xfrm_state *x, struct sk_buff *skb)
111 {
112 #if IS_ENABLED(CONFIG_IPV6)
113 struct ipv6hdr *iph;
114 u8 *prevhdr;
115 int hdr_len;
116
117 iph = ipv6_hdr(skb);
118
119 hdr_len = x->type->hdr_offset(x, skb, &prevhdr);
120 if (hdr_len < 0)
121 return hdr_len;
122 skb_set_mac_header(skb,
123 (prevhdr - x->props.header_len) - skb->data);
124 skb_set_network_header(skb, -x->props.header_len);
125 skb->transport_header = skb->network_header + hdr_len;
126 __skb_pull(skb, hdr_len);
127 memmove(ipv6_hdr(skb), iph, hdr_len);
128
129 x->lastused = ktime_get_real_seconds();
130
131 return 0;
132 #else
133 WARN_ON_ONCE(1);
134 return -EAFNOSUPPORT;
135 #endif
136 }
137
138 /* Add encapsulation header.
139 *
140 * The top IP header will be constructed per draft-nikander-esp-beet-mode-06.txt.
141 */
xfrm4_beet_encap_add(struct xfrm_state * x,struct sk_buff * skb)142 static int xfrm4_beet_encap_add(struct xfrm_state *x, struct sk_buff *skb)
143 {
144 struct ip_beet_phdr *ph;
145 struct iphdr *top_iph;
146 int hdrlen, optlen;
147
148 hdrlen = 0;
149 optlen = XFRM_MODE_SKB_CB(skb)->optlen;
150 if (unlikely(optlen))
151 hdrlen += IPV4_BEET_PHMAXLEN - (optlen & 4);
152
153 skb_set_network_header(skb, -x->props.header_len - hdrlen +
154 (XFRM_MODE_SKB_CB(skb)->ihl - sizeof(*top_iph)));
155 if (x->sel.family != AF_INET6)
156 skb->network_header += IPV4_BEET_PHMAXLEN;
157 skb->mac_header = skb->network_header +
158 offsetof(struct iphdr, protocol);
159 skb->transport_header = skb->network_header + sizeof(*top_iph);
160
161 xfrm4_beet_make_header(skb);
162
163 ph = __skb_pull(skb, XFRM_MODE_SKB_CB(skb)->ihl - hdrlen);
164
165 top_iph = ip_hdr(skb);
166
167 if (unlikely(optlen)) {
168 if (WARN_ON(optlen < 0))
169 return -EINVAL;
170
171 ph->padlen = 4 - (optlen & 4);
172 ph->hdrlen = optlen / 8;
173 ph->nexthdr = top_iph->protocol;
174 if (ph->padlen)
175 memset(ph + 1, IPOPT_NOP, ph->padlen);
176
177 top_iph->protocol = IPPROTO_BEETPH;
178 top_iph->ihl = sizeof(struct iphdr) / 4;
179 }
180
181 top_iph->saddr = x->props.saddr.a4;
182 top_iph->daddr = x->id.daddr.a4;
183
184 return 0;
185 }
186
187 /* Add encapsulation header.
188 *
189 * The top IP header will be constructed per RFC 2401.
190 */
xfrm4_tunnel_encap_add(struct xfrm_state * x,struct sk_buff * skb)191 static int xfrm4_tunnel_encap_add(struct xfrm_state *x, struct sk_buff *skb)
192 {
193 struct dst_entry *dst = skb_dst(skb);
194 struct iphdr *top_iph;
195 int flags;
196
197 skb_set_inner_network_header(skb, skb_network_offset(skb));
198 skb_set_inner_transport_header(skb, skb_transport_offset(skb));
199
200 skb_set_network_header(skb, -x->props.header_len);
201 skb->mac_header = skb->network_header +
202 offsetof(struct iphdr, protocol);
203 skb->transport_header = skb->network_header + sizeof(*top_iph);
204 top_iph = ip_hdr(skb);
205
206 top_iph->ihl = 5;
207 top_iph->version = 4;
208
209 top_iph->protocol = xfrm_af2proto(skb_dst(skb)->ops->family);
210
211 /* DS disclosing depends on XFRM_SA_XFLAG_DONT_ENCAP_DSCP */
212 if (x->props.extra_flags & XFRM_SA_XFLAG_DONT_ENCAP_DSCP)
213 top_iph->tos = 0;
214 else
215 top_iph->tos = XFRM_MODE_SKB_CB(skb)->tos;
216 top_iph->tos = INET_ECN_encapsulate(top_iph->tos,
217 XFRM_MODE_SKB_CB(skb)->tos);
218
219 flags = x->props.flags;
220 if (flags & XFRM_STATE_NOECN)
221 IP_ECN_clear(top_iph);
222
223 top_iph->frag_off = (flags & XFRM_STATE_NOPMTUDISC) ?
224 0 : (XFRM_MODE_SKB_CB(skb)->frag_off & htons(IP_DF));
225
226 top_iph->ttl = ip4_dst_hoplimit(xfrm_dst_child(dst));
227
228 top_iph->saddr = x->props.saddr.a4;
229 top_iph->daddr = x->id.daddr.a4;
230 ip_select_ident(dev_net(dst->dev), skb, NULL);
231
232 return 0;
233 }
234
235 #if IS_ENABLED(CONFIG_IPV6)
xfrm6_tunnel_encap_add(struct xfrm_state * x,struct sk_buff * skb)236 static int xfrm6_tunnel_encap_add(struct xfrm_state *x, struct sk_buff *skb)
237 {
238 struct dst_entry *dst = skb_dst(skb);
239 struct ipv6hdr *top_iph;
240 int dsfield;
241
242 skb_set_inner_network_header(skb, skb_network_offset(skb));
243 skb_set_inner_transport_header(skb, skb_transport_offset(skb));
244
245 skb_set_network_header(skb, -x->props.header_len);
246 skb->mac_header = skb->network_header +
247 offsetof(struct ipv6hdr, nexthdr);
248 skb->transport_header = skb->network_header + sizeof(*top_iph);
249 top_iph = ipv6_hdr(skb);
250
251 top_iph->version = 6;
252
253 memcpy(top_iph->flow_lbl, XFRM_MODE_SKB_CB(skb)->flow_lbl,
254 sizeof(top_iph->flow_lbl));
255 top_iph->nexthdr = xfrm_af2proto(skb_dst(skb)->ops->family);
256
257 if (x->props.extra_flags & XFRM_SA_XFLAG_DONT_ENCAP_DSCP)
258 dsfield = 0;
259 else
260 dsfield = XFRM_MODE_SKB_CB(skb)->tos;
261 dsfield = INET_ECN_encapsulate(dsfield, XFRM_MODE_SKB_CB(skb)->tos);
262 if (x->props.flags & XFRM_STATE_NOECN)
263 dsfield &= ~INET_ECN_MASK;
264 ipv6_change_dsfield(top_iph, 0, dsfield);
265 top_iph->hop_limit = ip6_dst_hoplimit(xfrm_dst_child(dst));
266 top_iph->saddr = *(struct in6_addr *)&x->props.saddr;
267 top_iph->daddr = *(struct in6_addr *)&x->id.daddr;
268 return 0;
269 }
270
xfrm6_beet_encap_add(struct xfrm_state * x,struct sk_buff * skb)271 static int xfrm6_beet_encap_add(struct xfrm_state *x, struct sk_buff *skb)
272 {
273 struct ipv6hdr *top_iph;
274 struct ip_beet_phdr *ph;
275 int optlen, hdr_len;
276
277 hdr_len = 0;
278 optlen = XFRM_MODE_SKB_CB(skb)->optlen;
279 if (unlikely(optlen))
280 hdr_len += IPV4_BEET_PHMAXLEN - (optlen & 4);
281
282 skb_set_network_header(skb, -x->props.header_len - hdr_len);
283 if (x->sel.family != AF_INET6)
284 skb->network_header += IPV4_BEET_PHMAXLEN;
285 skb->mac_header = skb->network_header +
286 offsetof(struct ipv6hdr, nexthdr);
287 skb->transport_header = skb->network_header + sizeof(*top_iph);
288 ph = __skb_pull(skb, XFRM_MODE_SKB_CB(skb)->ihl - hdr_len);
289
290 xfrm6_beet_make_header(skb);
291
292 top_iph = ipv6_hdr(skb);
293 if (unlikely(optlen)) {
294 if (WARN_ON(optlen < 0))
295 return -EINVAL;
296
297 ph->padlen = 4 - (optlen & 4);
298 ph->hdrlen = optlen / 8;
299 ph->nexthdr = top_iph->nexthdr;
300 if (ph->padlen)
301 memset(ph + 1, IPOPT_NOP, ph->padlen);
302
303 top_iph->nexthdr = IPPROTO_BEETPH;
304 }
305
306 top_iph->saddr = *(struct in6_addr *)&x->props.saddr;
307 top_iph->daddr = *(struct in6_addr *)&x->id.daddr;
308 return 0;
309 }
310 #endif
311
312 /* Add encapsulation header.
313 *
314 * On exit, the transport header will be set to the start of the
315 * encapsulation header to be filled in by x->type->output and the mac
316 * header will be set to the nextheader (protocol for IPv4) field of the
317 * extension header directly preceding the encapsulation header, or in
318 * its absence, that of the top IP header.
319 * The value of the network header will always point to the top IP header
320 * while skb->data will point to the payload.
321 */
xfrm4_prepare_output(struct xfrm_state * x,struct sk_buff * skb)322 static int xfrm4_prepare_output(struct xfrm_state *x, struct sk_buff *skb)
323 {
324 int err;
325
326 err = xfrm_inner_extract_output(x, skb);
327 if (err)
328 return err;
329
330 IPCB(skb)->flags |= IPSKB_XFRM_TUNNEL_SIZE;
331 skb->protocol = htons(ETH_P_IP);
332
333 switch (x->outer_mode.encap) {
334 case XFRM_MODE_BEET:
335 return xfrm4_beet_encap_add(x, skb);
336 case XFRM_MODE_TUNNEL:
337 return xfrm4_tunnel_encap_add(x, skb);
338 }
339
340 WARN_ON_ONCE(1);
341 return -EOPNOTSUPP;
342 }
343
xfrm6_prepare_output(struct xfrm_state * x,struct sk_buff * skb)344 static int xfrm6_prepare_output(struct xfrm_state *x, struct sk_buff *skb)
345 {
346 #if IS_ENABLED(CONFIG_IPV6)
347 int err;
348
349 err = xfrm_inner_extract_output(x, skb);
350 if (err)
351 return err;
352
353 skb->ignore_df = 1;
354 skb->protocol = htons(ETH_P_IPV6);
355
356 switch (x->outer_mode.encap) {
357 case XFRM_MODE_BEET:
358 return xfrm6_beet_encap_add(x, skb);
359 case XFRM_MODE_TUNNEL:
360 return xfrm6_tunnel_encap_add(x, skb);
361 default:
362 WARN_ON_ONCE(1);
363 return -EOPNOTSUPP;
364 }
365 #endif
366 WARN_ON_ONCE(1);
367 return -EAFNOSUPPORT;
368 }
369
xfrm_outer_mode_output(struct xfrm_state * x,struct sk_buff * skb)370 static int xfrm_outer_mode_output(struct xfrm_state *x, struct sk_buff *skb)
371 {
372 switch (x->outer_mode.encap) {
373 case XFRM_MODE_BEET:
374 case XFRM_MODE_TUNNEL:
375 if (x->outer_mode.family == AF_INET)
376 return xfrm4_prepare_output(x, skb);
377 if (x->outer_mode.family == AF_INET6)
378 return xfrm6_prepare_output(x, skb);
379 break;
380 case XFRM_MODE_TRANSPORT:
381 if (x->outer_mode.family == AF_INET)
382 return xfrm4_transport_output(x, skb);
383 if (x->outer_mode.family == AF_INET6)
384 return xfrm6_transport_output(x, skb);
385 break;
386 case XFRM_MODE_ROUTEOPTIMIZATION:
387 if (x->outer_mode.family == AF_INET6)
388 return xfrm6_ro_output(x, skb);
389 WARN_ON_ONCE(1);
390 break;
391 default:
392 WARN_ON_ONCE(1);
393 break;
394 }
395
396 return -EOPNOTSUPP;
397 }
398
399 #if IS_ENABLED(CONFIG_NET_PKTGEN)
pktgen_xfrm_outer_mode_output(struct xfrm_state * x,struct sk_buff * skb)400 int pktgen_xfrm_outer_mode_output(struct xfrm_state *x, struct sk_buff *skb)
401 {
402 return xfrm_outer_mode_output(x, skb);
403 }
404 EXPORT_SYMBOL_GPL(pktgen_xfrm_outer_mode_output);
405 #endif
406
xfrm_output_one(struct sk_buff * skb,int err)407 static int xfrm_output_one(struct sk_buff *skb, int err)
408 {
409 struct dst_entry *dst = skb_dst(skb);
410 struct xfrm_state *x = dst->xfrm;
411 struct net *net = xs_net(x);
412
413 if (err <= 0)
414 goto resume;
415
416 do {
417 err = xfrm_skb_check_space(skb);
418 if (err) {
419 XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTERROR);
420 goto error_nolock;
421 }
422
423 skb->mark = xfrm_smark_get(skb->mark, x);
424
425 err = xfrm_outer_mode_output(x, skb);
426 if (err) {
427 XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATEMODEERROR);
428 goto error_nolock;
429 }
430
431 spin_lock_bh(&x->lock);
432
433 if (unlikely(x->km.state != XFRM_STATE_VALID)) {
434 XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATEINVALID);
435 err = -EINVAL;
436 goto error;
437 }
438
439 err = xfrm_state_check_expire(x);
440 if (err) {
441 XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATEEXPIRED);
442 goto error;
443 }
444
445 err = x->repl->overflow(x, skb);
446 if (err) {
447 XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATESEQERROR);
448 goto error;
449 }
450
451 x->curlft.bytes += skb->len;
452 x->curlft.packets++;
453
454 spin_unlock_bh(&x->lock);
455
456 skb_dst_force(skb);
457 if (!skb_dst(skb)) {
458 XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTERROR);
459 err = -EHOSTUNREACH;
460 goto error_nolock;
461 }
462
463 if (xfrm_offload(skb)) {
464 x->type_offload->encap(x, skb);
465 } else {
466 /* Inner headers are invalid now. */
467 skb->encapsulation = 0;
468
469 err = x->type->output(x, skb);
470 if (err == -EINPROGRESS)
471 goto out;
472 }
473
474 resume:
475 if (err) {
476 XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATEPROTOERROR);
477 goto error_nolock;
478 }
479
480 dst = skb_dst_pop(skb);
481 if (!dst) {
482 XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTERROR);
483 err = -EHOSTUNREACH;
484 goto error_nolock;
485 }
486 skb_dst_set(skb, dst);
487 x = dst->xfrm;
488 } while (x && !(x->outer_mode.flags & XFRM_MODE_FLAG_TUNNEL));
489
490 return 0;
491
492 error:
493 spin_unlock_bh(&x->lock);
494 error_nolock:
495 kfree_skb(skb);
496 out:
497 return err;
498 }
499
xfrm_output_resume(struct sk_buff * skb,int err)500 int xfrm_output_resume(struct sk_buff *skb, int err)
501 {
502 struct net *net = xs_net(skb_dst(skb)->xfrm);
503
504 while (likely((err = xfrm_output_one(skb, err)) == 0)) {
505 nf_reset_ct(skb);
506
507 err = skb_dst(skb)->ops->local_out(net, skb->sk, skb);
508 if (unlikely(err != 1))
509 goto out;
510
511 if (!skb_dst(skb)->xfrm)
512 return dst_output(net, skb->sk, skb);
513
514 err = nf_hook(skb_dst(skb)->ops->family,
515 NF_INET_POST_ROUTING, net, skb->sk, skb,
516 NULL, skb_dst(skb)->dev, xfrm_output2);
517 if (unlikely(err != 1))
518 goto out;
519 }
520
521 if (err == -EINPROGRESS)
522 err = 0;
523
524 out:
525 return err;
526 }
527 EXPORT_SYMBOL_GPL(xfrm_output_resume);
528
xfrm_output2(struct net * net,struct sock * sk,struct sk_buff * skb)529 static int xfrm_output2(struct net *net, struct sock *sk, struct sk_buff *skb)
530 {
531 return xfrm_output_resume(skb, 1);
532 }
533
xfrm_output_gso(struct net * net,struct sock * sk,struct sk_buff * skb)534 static int xfrm_output_gso(struct net *net, struct sock *sk, struct sk_buff *skb)
535 {
536 struct sk_buff *segs;
537
538 BUILD_BUG_ON(sizeof(*IPCB(skb)) > SKB_SGO_CB_OFFSET);
539 BUILD_BUG_ON(sizeof(*IP6CB(skb)) > SKB_SGO_CB_OFFSET);
540 segs = skb_gso_segment(skb, 0);
541 kfree_skb(skb);
542 if (IS_ERR(segs))
543 return PTR_ERR(segs);
544 if (segs == NULL)
545 return -EINVAL;
546
547 do {
548 struct sk_buff *nskb = segs->next;
549 int err;
550
551 skb_mark_not_on_list(segs);
552 err = xfrm_output2(net, sk, segs);
553
554 if (unlikely(err)) {
555 kfree_skb_list(nskb);
556 return err;
557 }
558
559 segs = nskb;
560 } while (segs);
561
562 return 0;
563 }
564
xfrm_output(struct sock * sk,struct sk_buff * skb)565 int xfrm_output(struct sock *sk, struct sk_buff *skb)
566 {
567 struct net *net = dev_net(skb_dst(skb)->dev);
568 struct xfrm_state *x = skb_dst(skb)->xfrm;
569 int err;
570
571 secpath_reset(skb);
572
573 if (xfrm_dev_offload_ok(skb, x)) {
574 struct sec_path *sp;
575
576 sp = secpath_set(skb);
577 if (!sp) {
578 XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTERROR);
579 kfree_skb(skb);
580 return -ENOMEM;
581 }
582 skb->encapsulation = 1;
583
584 sp->olen++;
585 sp->xvec[sp->len++] = x;
586 xfrm_state_hold(x);
587
588 if (skb_is_gso(skb)) {
589 skb_shinfo(skb)->gso_type |= SKB_GSO_ESP;
590
591 return xfrm_output2(net, sk, skb);
592 }
593
594 if (x->xso.dev && x->xso.dev->features & NETIF_F_HW_ESP_TX_CSUM)
595 goto out;
596 }
597
598 if (skb_is_gso(skb))
599 return xfrm_output_gso(net, sk, skb);
600
601 if (skb->ip_summed == CHECKSUM_PARTIAL) {
602 err = skb_checksum_help(skb);
603 if (err) {
604 XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTERROR);
605 kfree_skb(skb);
606 return err;
607 }
608 }
609
610 out:
611 return xfrm_output2(net, sk, skb);
612 }
613 EXPORT_SYMBOL_GPL(xfrm_output);
614
xfrm_inner_extract_output(struct xfrm_state * x,struct sk_buff * skb)615 static int xfrm_inner_extract_output(struct xfrm_state *x, struct sk_buff *skb)
616 {
617 const struct xfrm_state_afinfo *afinfo;
618 const struct xfrm_mode *inner_mode;
619 int err = -EAFNOSUPPORT;
620
621 if (x->sel.family == AF_UNSPEC)
622 inner_mode = xfrm_ip2inner_mode(x,
623 xfrm_af2proto(skb_dst(skb)->ops->family));
624 else
625 inner_mode = &x->inner_mode;
626
627 if (inner_mode == NULL)
628 return -EAFNOSUPPORT;
629
630 rcu_read_lock();
631 afinfo = xfrm_state_afinfo_get_rcu(inner_mode->family);
632 if (likely(afinfo))
633 err = afinfo->extract_output(x, skb);
634 rcu_read_unlock();
635
636 return err;
637 }
638
xfrm_local_error(struct sk_buff * skb,int mtu)639 void xfrm_local_error(struct sk_buff *skb, int mtu)
640 {
641 unsigned int proto;
642 struct xfrm_state_afinfo *afinfo;
643
644 if (skb->protocol == htons(ETH_P_IP))
645 proto = AF_INET;
646 else if (skb->protocol == htons(ETH_P_IPV6))
647 proto = AF_INET6;
648 else
649 return;
650
651 afinfo = xfrm_state_get_afinfo(proto);
652 if (afinfo) {
653 afinfo->local_error(skb, mtu);
654 rcu_read_unlock();
655 }
656 }
657 EXPORT_SYMBOL_GPL(xfrm_local_error);
658