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/icmp.h>
 17#include <net/inet_ecn.h>
 18#include <net/xfrm.h>
 19
 20#if IS_ENABLED(CONFIG_IPV6)
 21#include <net/ip6_route.h>
 22#include <net/ipv6_stubs.h>
 23#endif
 24
 25#include "xfrm_inout.h"
 26
 27static int xfrm_output2(struct net *net, struct sock *sk, struct sk_buff *skb);
 28static int xfrm_inner_extract_output(struct xfrm_state *x, struct sk_buff *skb);
 29
 30static int xfrm_skb_check_space(struct sk_buff *skb)
 31{
 32	struct dst_entry *dst = skb_dst(skb);
 33	int nhead = dst->header_len + LL_RESERVED_SPACE(dst->dev)
 34		- skb_headroom(skb);
 35	int ntail = dst->dev->needed_tailroom - skb_tailroom(skb);
 36
 37	if (nhead <= 0) {
 38		if (ntail <= 0)
 39			return 0;
 40		nhead = 0;
 41	} else if (ntail < 0)
 42		ntail = 0;
 43
 44	return pskb_expand_head(skb, nhead, ntail, GFP_ATOMIC);
 45}
 46
 47/* Children define the path of the packet through the
 48 * Linux networking.  Thus, destinations are stackable.
 49 */
 50
 51static struct dst_entry *skb_dst_pop(struct sk_buff *skb)
 52{
 53	struct dst_entry *child = dst_clone(xfrm_dst_child(skb_dst(skb)));
 54
 55	skb_dst_drop(skb);
 56	return child;
 57}
 58
 59/* Add encapsulation header.
 60 *
 61 * The IP header will be moved forward to make space for the encapsulation
 62 * header.
 63 */
 64static int xfrm4_transport_output(struct xfrm_state *x, struct sk_buff *skb)
 65{
 66	struct iphdr *iph = ip_hdr(skb);
 67	int ihl = iph->ihl * 4;
 68
 69	skb_set_inner_transport_header(skb, skb_transport_offset(skb));
 70
 71	skb_set_network_header(skb, -x->props.header_len);
 72	skb->mac_header = skb->network_header +
 73			  offsetof(struct iphdr, protocol);
 74	skb->transport_header = skb->network_header + ihl;
 75	__skb_pull(skb, ihl);
 76	memmove(skb_network_header(skb), iph, ihl);
 77	return 0;
 78}
 79
 80/* Add encapsulation header.
 81 *
 82 * The IP header and mutable extension headers will be moved forward to make
 83 * space for the encapsulation header.
 84 */
 85static int xfrm6_transport_output(struct xfrm_state *x, struct sk_buff *skb)
 86{
 87#if IS_ENABLED(CONFIG_IPV6)
 88	struct ipv6hdr *iph;
 89	u8 *prevhdr;
 90	int hdr_len;
 91
 92	iph = ipv6_hdr(skb);
 93	skb_set_inner_transport_header(skb, skb_transport_offset(skb));
 94
 95	hdr_len = x->type->hdr_offset(x, skb, &prevhdr);
 96	if (hdr_len < 0)
 97		return hdr_len;
 98	skb_set_mac_header(skb,
 99			   (prevhdr - x->props.header_len) - skb->data);
100	skb_set_network_header(skb, -x->props.header_len);
101	skb->transport_header = skb->network_header + hdr_len;
102	__skb_pull(skb, hdr_len);
103	memmove(ipv6_hdr(skb), iph, hdr_len);
104	return 0;
105#else
106	WARN_ON_ONCE(1);
107	return -EAFNOSUPPORT;
108#endif
109}
110
111/* Add route optimization header space.
112 *
113 * The IP header and mutable extension headers will be moved forward to make
114 * space for the route optimization header.
115 */
116static int xfrm6_ro_output(struct xfrm_state *x, struct sk_buff *skb)
117{
118#if IS_ENABLED(CONFIG_IPV6)
119	struct ipv6hdr *iph;
120	u8 *prevhdr;
121	int hdr_len;
122
123	iph = ipv6_hdr(skb);
124
125	hdr_len = x->type->hdr_offset(x, skb, &prevhdr);
126	if (hdr_len < 0)
127		return hdr_len;
128	skb_set_mac_header(skb,
129			   (prevhdr - x->props.header_len) - skb->data);
130	skb_set_network_header(skb, -x->props.header_len);
131	skb->transport_header = skb->network_header + hdr_len;
132	__skb_pull(skb, hdr_len);
133	memmove(ipv6_hdr(skb), iph, hdr_len);
134
135	x->lastused = ktime_get_real_seconds();
136
137	return 0;
138#else
139	WARN_ON_ONCE(1);
140	return -EAFNOSUPPORT;
141#endif
142}
143
144/* Add encapsulation header.
145 *
146 * The top IP header will be constructed per draft-nikander-esp-beet-mode-06.txt.
147 */
148static int xfrm4_beet_encap_add(struct xfrm_state *x, struct sk_buff *skb)
149{
150	struct ip_beet_phdr *ph;
151	struct iphdr *top_iph;
152	int hdrlen, optlen;
153
154	hdrlen = 0;
155	optlen = XFRM_MODE_SKB_CB(skb)->optlen;
156	if (unlikely(optlen))
157		hdrlen += IPV4_BEET_PHMAXLEN - (optlen & 4);
158
159	skb_set_network_header(skb, -x->props.header_len - hdrlen +
160			       (XFRM_MODE_SKB_CB(skb)->ihl - sizeof(*top_iph)));
161	if (x->sel.family != AF_INET6)
162		skb->network_header += IPV4_BEET_PHMAXLEN;
163	skb->mac_header = skb->network_header +
164			  offsetof(struct iphdr, protocol);
165	skb->transport_header = skb->network_header + sizeof(*top_iph);
166
167	xfrm4_beet_make_header(skb);
168
169	ph = __skb_pull(skb, XFRM_MODE_SKB_CB(skb)->ihl - hdrlen);
170
171	top_iph = ip_hdr(skb);
172
173	if (unlikely(optlen)) {
174		if (WARN_ON(optlen < 0))
175			return -EINVAL;
176
177		ph->padlen = 4 - (optlen & 4);
178		ph->hdrlen = optlen / 8;
179		ph->nexthdr = top_iph->protocol;
180		if (ph->padlen)
181			memset(ph + 1, IPOPT_NOP, ph->padlen);
182
183		top_iph->protocol = IPPROTO_BEETPH;
184		top_iph->ihl = sizeof(struct iphdr) / 4;
185	}
186
187	top_iph->saddr = x->props.saddr.a4;
188	top_iph->daddr = x->id.daddr.a4;
189
190	return 0;
191}
192
193/* Add encapsulation header.
194 *
195 * The top IP header will be constructed per RFC 2401.
196 */
197static int xfrm4_tunnel_encap_add(struct xfrm_state *x, struct sk_buff *skb)
198{
199	struct dst_entry *dst = skb_dst(skb);
200	struct iphdr *top_iph;
201	int flags;
202
203	skb_set_inner_network_header(skb, skb_network_offset(skb));
204	skb_set_inner_transport_header(skb, skb_transport_offset(skb));
205
206	skb_set_network_header(skb, -x->props.header_len);
207	skb->mac_header = skb->network_header +
208			  offsetof(struct iphdr, protocol);
209	skb->transport_header = skb->network_header + sizeof(*top_iph);
210	top_iph = ip_hdr(skb);
211
212	top_iph->ihl = 5;
213	top_iph->version = 4;
214
215	top_iph->protocol = xfrm_af2proto(skb_dst(skb)->ops->family);
216
217	/* DS disclosing depends on XFRM_SA_XFLAG_DONT_ENCAP_DSCP */
218	if (x->props.extra_flags & XFRM_SA_XFLAG_DONT_ENCAP_DSCP)
219		top_iph->tos = 0;
220	else
221		top_iph->tos = XFRM_MODE_SKB_CB(skb)->tos;
222	top_iph->tos = INET_ECN_encapsulate(top_iph->tos,
223					    XFRM_MODE_SKB_CB(skb)->tos);
224
225	flags = x->props.flags;
226	if (flags & XFRM_STATE_NOECN)
227		IP_ECN_clear(top_iph);
228
229	top_iph->frag_off = (flags & XFRM_STATE_NOPMTUDISC) ?
230		0 : (XFRM_MODE_SKB_CB(skb)->frag_off & htons(IP_DF));
231
232	top_iph->ttl = ip4_dst_hoplimit(xfrm_dst_child(dst));
233
234	top_iph->saddr = x->props.saddr.a4;
235	top_iph->daddr = x->id.daddr.a4;
236	ip_select_ident(dev_net(dst->dev), skb, NULL);
237
238	return 0;
239}
240
241#if IS_ENABLED(CONFIG_IPV6)
242static int xfrm6_tunnel_encap_add(struct xfrm_state *x, struct sk_buff *skb)
243{
244	struct dst_entry *dst = skb_dst(skb);
245	struct ipv6hdr *top_iph;
246	int dsfield;
247
248	skb_set_inner_network_header(skb, skb_network_offset(skb));
249	skb_set_inner_transport_header(skb, skb_transport_offset(skb));
250
251	skb_set_network_header(skb, -x->props.header_len);
252	skb->mac_header = skb->network_header +
253			  offsetof(struct ipv6hdr, nexthdr);
254	skb->transport_header = skb->network_header + sizeof(*top_iph);
255	top_iph = ipv6_hdr(skb);
256
257	top_iph->version = 6;
258
259	memcpy(top_iph->flow_lbl, XFRM_MODE_SKB_CB(skb)->flow_lbl,
260	       sizeof(top_iph->flow_lbl));
261	top_iph->nexthdr = xfrm_af2proto(skb_dst(skb)->ops->family);
262
263	if (x->props.extra_flags & XFRM_SA_XFLAG_DONT_ENCAP_DSCP)
264		dsfield = 0;
265	else
266		dsfield = XFRM_MODE_SKB_CB(skb)->tos;
267	dsfield = INET_ECN_encapsulate(dsfield, XFRM_MODE_SKB_CB(skb)->tos);
268	if (x->props.flags & XFRM_STATE_NOECN)
269		dsfield &= ~INET_ECN_MASK;
270	ipv6_change_dsfield(top_iph, 0, dsfield);
271	top_iph->hop_limit = ip6_dst_hoplimit(xfrm_dst_child(dst));
272	top_iph->saddr = *(struct in6_addr *)&x->props.saddr;
273	top_iph->daddr = *(struct in6_addr *)&x->id.daddr;
274	return 0;
275}
276
277static int xfrm6_beet_encap_add(struct xfrm_state *x, struct sk_buff *skb)
278{
279	struct ipv6hdr *top_iph;
280	struct ip_beet_phdr *ph;
281	int optlen, hdr_len;
282
283	hdr_len = 0;
284	optlen = XFRM_MODE_SKB_CB(skb)->optlen;
285	if (unlikely(optlen))
286		hdr_len += IPV4_BEET_PHMAXLEN - (optlen & 4);
287
288	skb_set_network_header(skb, -x->props.header_len - hdr_len);
289	if (x->sel.family != AF_INET6)
290		skb->network_header += IPV4_BEET_PHMAXLEN;
291	skb->mac_header = skb->network_header +
292			  offsetof(struct ipv6hdr, nexthdr);
293	skb->transport_header = skb->network_header + sizeof(*top_iph);
294	ph = __skb_pull(skb, XFRM_MODE_SKB_CB(skb)->ihl - hdr_len);
295
296	xfrm6_beet_make_header(skb);
297
298	top_iph = ipv6_hdr(skb);
299	if (unlikely(optlen)) {
300		if (WARN_ON(optlen < 0))
301			return -EINVAL;
302
303		ph->padlen = 4 - (optlen & 4);
304		ph->hdrlen = optlen / 8;
305		ph->nexthdr = top_iph->nexthdr;
306		if (ph->padlen)
307			memset(ph + 1, IPOPT_NOP, ph->padlen);
308
309		top_iph->nexthdr = IPPROTO_BEETPH;
310	}
311
312	top_iph->saddr = *(struct in6_addr *)&x->props.saddr;
313	top_iph->daddr = *(struct in6_addr *)&x->id.daddr;
314	return 0;
315}
316#endif
317
318/* Add encapsulation header.
319 *
320 * On exit, the transport header will be set to the start of the
321 * encapsulation header to be filled in by x->type->output and the mac
322 * header will be set to the nextheader (protocol for IPv4) field of the
323 * extension header directly preceding the encapsulation header, or in
324 * its absence, that of the top IP header.
325 * The value of the network header will always point to the top IP header
326 * while skb->data will point to the payload.
327 */
328static int xfrm4_prepare_output(struct xfrm_state *x, struct sk_buff *skb)
329{
330	int err;
331
332	err = xfrm_inner_extract_output(x, skb);
333	if (err)
334		return err;
335
336	IPCB(skb)->flags |= IPSKB_XFRM_TUNNEL_SIZE;
337	skb->protocol = htons(ETH_P_IP);
338
339	switch (x->outer_mode.encap) {
340	case XFRM_MODE_BEET:
341		return xfrm4_beet_encap_add(x, skb);
342	case XFRM_MODE_TUNNEL:
343		return xfrm4_tunnel_encap_add(x, skb);
344	}
345
346	WARN_ON_ONCE(1);
347	return -EOPNOTSUPP;
348}
349
350static int xfrm6_prepare_output(struct xfrm_state *x, struct sk_buff *skb)
351{
352#if IS_ENABLED(CONFIG_IPV6)
353	int err;
354
355	err = xfrm_inner_extract_output(x, skb);
356	if (err)
357		return err;
358
359	skb->ignore_df = 1;
360	skb->protocol = htons(ETH_P_IPV6);
361
362	switch (x->outer_mode.encap) {
363	case XFRM_MODE_BEET:
364		return xfrm6_beet_encap_add(x, skb);
365	case XFRM_MODE_TUNNEL:
366		return xfrm6_tunnel_encap_add(x, skb);
367	default:
368		WARN_ON_ONCE(1);
369		return -EOPNOTSUPP;
370	}
371#endif
372	WARN_ON_ONCE(1);
373	return -EAFNOSUPPORT;
374}
375
376static int xfrm_outer_mode_output(struct xfrm_state *x, struct sk_buff *skb)
377{
378	switch (x->outer_mode.encap) {
379	case XFRM_MODE_BEET:
380	case XFRM_MODE_TUNNEL:
381		if (x->outer_mode.family == AF_INET)
382			return xfrm4_prepare_output(x, skb);
383		if (x->outer_mode.family == AF_INET6)
384			return xfrm6_prepare_output(x, skb);
385		break;
386	case XFRM_MODE_TRANSPORT:
387		if (x->outer_mode.family == AF_INET)
388			return xfrm4_transport_output(x, skb);
389		if (x->outer_mode.family == AF_INET6)
390			return xfrm6_transport_output(x, skb);
391		break;
392	case XFRM_MODE_ROUTEOPTIMIZATION:
393		if (x->outer_mode.family == AF_INET6)
394			return xfrm6_ro_output(x, skb);
395		WARN_ON_ONCE(1);
396		break;
397	default:
398		WARN_ON_ONCE(1);
399		break;
400	}
401
402	return -EOPNOTSUPP;
403}
404
405#if IS_ENABLED(CONFIG_NET_PKTGEN)
406int pktgen_xfrm_outer_mode_output(struct xfrm_state *x, struct sk_buff *skb)
407{
408	return xfrm_outer_mode_output(x, skb);
409}
410EXPORT_SYMBOL_GPL(pktgen_xfrm_outer_mode_output);
411#endif
412
413static int xfrm_output_one(struct sk_buff *skb, int err)
414{
415	struct dst_entry *dst = skb_dst(skb);
416	struct xfrm_state *x = dst->xfrm;
417	struct net *net = xs_net(x);
418
419	if (err <= 0)
420		goto resume;
421
422	do {
423		err = xfrm_skb_check_space(skb);
424		if (err) {
425			XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTERROR);
426			goto error_nolock;
427		}
428
429		skb->mark = xfrm_smark_get(skb->mark, x);
430
431		err = xfrm_outer_mode_output(x, skb);
432		if (err) {
433			XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATEMODEERROR);
434			goto error_nolock;
435		}
436
437		spin_lock_bh(&x->lock);
438
439		if (unlikely(x->km.state != XFRM_STATE_VALID)) {
440			XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATEINVALID);
441			err = -EINVAL;
442			goto error;
443		}
444
445		err = xfrm_state_check_expire(x);
446		if (err) {
447			XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATEEXPIRED);
448			goto error;
449		}
450
451		err = x->repl->overflow(x, skb);
452		if (err) {
453			XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATESEQERROR);
454			goto error;
455		}
456
457		x->curlft.bytes += skb->len;
458		x->curlft.packets++;
459
460		spin_unlock_bh(&x->lock);
461
462		skb_dst_force(skb);
463		if (!skb_dst(skb)) {
464			XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTERROR);
465			err = -EHOSTUNREACH;
466			goto error_nolock;
467		}
468
469		if (xfrm_offload(skb)) {
470			x->type_offload->encap(x, skb);
471		} else {
472			/* Inner headers are invalid now. */
473			skb->encapsulation = 0;
474
475			err = x->type->output(x, skb);
476			if (err == -EINPROGRESS)
477				goto out;
478		}
479
480resume:
481		if (err) {
482			XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATEPROTOERROR);
483			goto error_nolock;
484		}
485
486		dst = skb_dst_pop(skb);
487		if (!dst) {
488			XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTERROR);
489			err = -EHOSTUNREACH;
490			goto error_nolock;
491		}
492		skb_dst_set(skb, dst);
493		x = dst->xfrm;
494	} while (x && !(x->outer_mode.flags & XFRM_MODE_FLAG_TUNNEL));
495
496	return 0;
497
 
 
498error:
499	spin_unlock_bh(&x->lock);
500error_nolock:
501	kfree_skb(skb);
502out:
503	return err;
504}
505
506int xfrm_output_resume(struct sk_buff *skb, int err)
507{
508	struct net *net = xs_net(skb_dst(skb)->xfrm);
509
510	while (likely((err = xfrm_output_one(skb, err)) == 0)) {
511		nf_reset_ct(skb);
512
513		err = skb_dst(skb)->ops->local_out(net, skb->sk, skb);
514		if (unlikely(err != 1))
515			goto out;
516
517		if (!skb_dst(skb)->xfrm)
518			return dst_output(net, skb->sk, skb);
519
520		err = nf_hook(skb_dst(skb)->ops->family,
521			      NF_INET_POST_ROUTING, net, skb->sk, skb,
522			      NULL, skb_dst(skb)->dev, xfrm_output2);
523		if (unlikely(err != 1))
524			goto out;
525	}
526
527	if (err == -EINPROGRESS)
528		err = 0;
529
530out:
531	return err;
532}
533EXPORT_SYMBOL_GPL(xfrm_output_resume);
534
535static int xfrm_output2(struct net *net, struct sock *sk, struct sk_buff *skb)
536{
537	return xfrm_output_resume(skb, 1);
538}
539
540static int xfrm_output_gso(struct net *net, struct sock *sk, struct sk_buff *skb)
541{
542	struct sk_buff *segs, *nskb;
543
544	BUILD_BUG_ON(sizeof(*IPCB(skb)) > SKB_GSO_CB_OFFSET);
545	BUILD_BUG_ON(sizeof(*IP6CB(skb)) > SKB_GSO_CB_OFFSET);
546	segs = skb_gso_segment(skb, 0);
547	kfree_skb(skb);
548	if (IS_ERR(segs))
549		return PTR_ERR(segs);
550	if (segs == NULL)
551		return -EINVAL;
552
553	skb_list_walk_safe(segs, segs, nskb) {
 
554		int err;
555
556		skb_mark_not_on_list(segs);
557		err = xfrm_output2(net, sk, segs);
558
559		if (unlikely(err)) {
560			kfree_skb_list(nskb);
 
 
 
 
561			return err;
562		}
563	}
 
 
564
565	return 0;
566}
567
568int xfrm_output(struct sock *sk, struct sk_buff *skb)
569{
570	struct net *net = dev_net(skb_dst(skb)->dev);
571	struct xfrm_state *x = skb_dst(skb)->xfrm;
572	int err;
573
574	switch (x->outer_mode.family) {
575	case AF_INET:
576		memset(IPCB(skb), 0, sizeof(*IPCB(skb)));
577		IPCB(skb)->flags |= IPSKB_XFRM_TRANSFORMED;
578		break;
579	case AF_INET6:
580		memset(IP6CB(skb), 0, sizeof(*IP6CB(skb)));
581
582		IP6CB(skb)->flags |= IP6SKB_XFRM_TRANSFORMED;
583		break;
584	}
585
586	secpath_reset(skb);
587
588	if (xfrm_dev_offload_ok(skb, x)) {
589		struct sec_path *sp;
590
591		sp = secpath_set(skb);
592		if (!sp) {
593			XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTERROR);
594			kfree_skb(skb);
595			return -ENOMEM;
596		}
597		skb->encapsulation = 1;
598
599		sp->olen++;
600		sp->xvec[sp->len++] = x;
601		xfrm_state_hold(x);
602
603		if (skb_is_gso(skb)) {
604			if (skb->inner_protocol)
605				return xfrm_output_gso(net, sk, skb);
606
607			skb_shinfo(skb)->gso_type |= SKB_GSO_ESP;
608			goto out;
609		}
610
611		if (x->xso.dev && x->xso.dev->features & NETIF_F_HW_ESP_TX_CSUM)
612			goto out;
613	} else {
614		if (skb_is_gso(skb))
615			return xfrm_output_gso(net, sk, skb);
616	}
617
618	if (skb->ip_summed == CHECKSUM_PARTIAL) {
619		err = skb_checksum_help(skb);
620		if (err) {
621			XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTERROR);
622			kfree_skb(skb);
623			return err;
624		}
625	}
626
627out:
628	return xfrm_output2(net, sk, skb);
629}
630EXPORT_SYMBOL_GPL(xfrm_output);
631
632static int xfrm4_tunnel_check_size(struct sk_buff *skb)
633{
634	int mtu, ret = 0;
635
636	if (IPCB(skb)->flags & IPSKB_XFRM_TUNNEL_SIZE)
637		goto out;
638
639	if (!(ip_hdr(skb)->frag_off & htons(IP_DF)) || skb->ignore_df)
640		goto out;
641
642	mtu = dst_mtu(skb_dst(skb));
643	if ((!skb_is_gso(skb) && skb->len > mtu) ||
644	    (skb_is_gso(skb) &&
645	     !skb_gso_validate_network_len(skb, ip_skb_dst_mtu(skb->sk, skb)))) {
646		skb->protocol = htons(ETH_P_IP);
647
648		if (skb->sk)
649			xfrm_local_error(skb, mtu);
650		else
651			icmp_send(skb, ICMP_DEST_UNREACH,
652				  ICMP_FRAG_NEEDED, htonl(mtu));
653		ret = -EMSGSIZE;
654	}
655out:
656	return ret;
657}
658
659static int xfrm4_extract_output(struct xfrm_state *x, struct sk_buff *skb)
660{
661	int err;
662
663	err = xfrm4_tunnel_check_size(skb);
664	if (err)
665		return err;
666
667	XFRM_MODE_SKB_CB(skb)->protocol = ip_hdr(skb)->protocol;
668
669	xfrm4_extract_header(skb);
670	return 0;
671}
672
673#if IS_ENABLED(CONFIG_IPV6)
674static int xfrm6_tunnel_check_size(struct sk_buff *skb)
675{
676	int mtu, ret = 0;
677	struct dst_entry *dst = skb_dst(skb);
678
679	if (skb->ignore_df)
680		goto out;
681
682	mtu = dst_mtu(dst);
683	if (mtu < IPV6_MIN_MTU)
684		mtu = IPV6_MIN_MTU;
685
686	if ((!skb_is_gso(skb) && skb->len > mtu) ||
687	    (skb_is_gso(skb) &&
688	     !skb_gso_validate_network_len(skb, ip6_skb_dst_mtu(skb)))) {
689		skb->dev = dst->dev;
690		skb->protocol = htons(ETH_P_IPV6);
691
692		if (xfrm6_local_dontfrag(skb->sk))
693			ipv6_stub->xfrm6_local_rxpmtu(skb, mtu);
694		else if (skb->sk)
695			xfrm_local_error(skb, mtu);
696		else
697			icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu);
698		ret = -EMSGSIZE;
699	}
700out:
701	return ret;
702}
703#endif
704
705static int xfrm6_extract_output(struct xfrm_state *x, struct sk_buff *skb)
706{
707#if IS_ENABLED(CONFIG_IPV6)
708	int err;
709
710	err = xfrm6_tunnel_check_size(skb);
711	if (err)
712		return err;
713
714	XFRM_MODE_SKB_CB(skb)->protocol = ipv6_hdr(skb)->nexthdr;
715
716	xfrm6_extract_header(skb);
717	return 0;
718#else
719	WARN_ON_ONCE(1);
720	return -EAFNOSUPPORT;
721#endif
722}
723
724static int xfrm_inner_extract_output(struct xfrm_state *x, struct sk_buff *skb)
725{
726	const struct xfrm_mode *inner_mode;
727
728	if (x->sel.family == AF_UNSPEC)
729		inner_mode = xfrm_ip2inner_mode(x,
730				xfrm_af2proto(skb_dst(skb)->ops->family));
731	else
732		inner_mode = &x->inner_mode;
733
734	if (inner_mode == NULL)
735		return -EAFNOSUPPORT;
736
737	switch (inner_mode->family) {
738	case AF_INET:
739		return xfrm4_extract_output(x, skb);
740	case AF_INET6:
741		return xfrm6_extract_output(x, skb);
742	}
743
744	return -EAFNOSUPPORT;
745}
746
747void xfrm_local_error(struct sk_buff *skb, int mtu)
748{
749	unsigned int proto;
750	struct xfrm_state_afinfo *afinfo;
751
752	if (skb->protocol == htons(ETH_P_IP))
753		proto = AF_INET;
754	else if (skb->protocol == htons(ETH_P_IPV6) &&
755		 skb->sk->sk_family == AF_INET6)
756		proto = AF_INET6;
757	else
758		return;
759
760	afinfo = xfrm_state_get_afinfo(proto);
761	if (afinfo) {
762		afinfo->local_error(skb, mtu);
763		rcu_read_unlock();
764	}
765}
766EXPORT_SYMBOL_GPL(xfrm_local_error);