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#if IS_ENABLED(CONFIG_IPV6_MIP6)
 81static int mip6_rthdr_offset(struct sk_buff *skb, u8 **nexthdr, int type)
 82{
 83	const unsigned char *nh = skb_network_header(skb);
 84	unsigned int offset = sizeof(struct ipv6hdr);
 85	unsigned int packet_len;
 86	int found_rhdr = 0;
 87
 88	packet_len = skb_tail_pointer(skb) - nh;
 89	*nexthdr = &ipv6_hdr(skb)->nexthdr;
 90
 91	while (offset <= packet_len) {
 92		struct ipv6_opt_hdr *exthdr;
 93
 94		switch (**nexthdr) {
 95		case NEXTHDR_HOP:
 96			break;
 97		case NEXTHDR_ROUTING:
 98			if (type == IPPROTO_ROUTING && offset + 3 <= packet_len) {
 99				struct ipv6_rt_hdr *rt;
100
101				rt = (struct ipv6_rt_hdr *)(nh + offset);
102				if (rt->type != 0)
103					return offset;
104			}
105			found_rhdr = 1;
106			break;
107		case NEXTHDR_DEST:
108			/* HAO MUST NOT appear more than once.
109			 * XXX: It is better to try to find by the end of
110			 * XXX: packet if HAO exists.
111			 */
112			if (ipv6_find_tlv(skb, offset, IPV6_TLV_HAO) >= 0) {
113				net_dbg_ratelimited("mip6: hao exists already, override\n");
114				return offset;
115			}
116
117			if (found_rhdr)
118				return offset;
119
120			break;
121		default:
122			return offset;
123		}
124
125		if (offset + sizeof(struct ipv6_opt_hdr) > packet_len)
126			return -EINVAL;
127
128		exthdr = (struct ipv6_opt_hdr *)(skb_network_header(skb) +
129						 offset);
130		offset += ipv6_optlen(exthdr);
131		if (offset > IPV6_MAXPLEN)
132			return -EINVAL;
133		*nexthdr = &exthdr->nexthdr;
134	}
135
136	return -EINVAL;
137}
138#endif
139
140#if IS_ENABLED(CONFIG_IPV6)
141static int xfrm6_hdr_offset(struct xfrm_state *x, struct sk_buff *skb, u8 **prevhdr)
142{
143	switch (x->type->proto) {
144#if IS_ENABLED(CONFIG_IPV6_MIP6)
145	case IPPROTO_DSTOPTS:
146	case IPPROTO_ROUTING:
147		return mip6_rthdr_offset(skb, prevhdr, x->type->proto);
148#endif
149	default:
150		break;
151	}
152
153	return ip6_find_1stfragopt(skb, prevhdr);
154}
155#endif
156
157/* Add encapsulation header.
158 *
159 * The IP header and mutable extension headers will be moved forward to make
160 * space for the encapsulation header.
161 */
162static int xfrm6_transport_output(struct xfrm_state *x, struct sk_buff *skb)
163{
164#if IS_ENABLED(CONFIG_IPV6)
165	struct ipv6hdr *iph;
166	u8 *prevhdr;
167	int hdr_len;
168
169	iph = ipv6_hdr(skb);
170	skb_set_inner_transport_header(skb, skb_transport_offset(skb));
171
172	hdr_len = xfrm6_hdr_offset(x, skb, &prevhdr);
173	if (hdr_len < 0)
174		return hdr_len;
175	skb_set_mac_header(skb,
176			   (prevhdr - x->props.header_len) - skb->data);
177	skb_set_network_header(skb, -x->props.header_len);
178	skb->transport_header = skb->network_header + hdr_len;
179	__skb_pull(skb, hdr_len);
180	memmove(ipv6_hdr(skb), iph, hdr_len);
181	return 0;
182#else
183	WARN_ON_ONCE(1);
184	return -EAFNOSUPPORT;
185#endif
186}
187
188/* Add route optimization header space.
189 *
190 * The IP header and mutable extension headers will be moved forward to make
191 * space for the route optimization header.
192 */
193static int xfrm6_ro_output(struct xfrm_state *x, struct sk_buff *skb)
194{
195#if IS_ENABLED(CONFIG_IPV6)
196	struct ipv6hdr *iph;
197	u8 *prevhdr;
198	int hdr_len;
199
200	iph = ipv6_hdr(skb);
201
202	hdr_len = xfrm6_hdr_offset(x, skb, &prevhdr);
203	if (hdr_len < 0)
204		return hdr_len;
205	skb_set_mac_header(skb,
206			   (prevhdr - x->props.header_len) - skb->data);
207	skb_set_network_header(skb, -x->props.header_len);
208	skb->transport_header = skb->network_header + hdr_len;
209	__skb_pull(skb, hdr_len);
210	memmove(ipv6_hdr(skb), iph, hdr_len);
211
212	return 0;
213#else
214	WARN_ON_ONCE(1);
215	return -EAFNOSUPPORT;
216#endif
217}
218
219/* Add encapsulation header.
220 *
221 * The top IP header will be constructed per draft-nikander-esp-beet-mode-06.txt.
222 */
223static int xfrm4_beet_encap_add(struct xfrm_state *x, struct sk_buff *skb)
224{
225	struct ip_beet_phdr *ph;
226	struct iphdr *top_iph;
227	int hdrlen, optlen;
228
229	hdrlen = 0;
230	optlen = XFRM_MODE_SKB_CB(skb)->optlen;
231	if (unlikely(optlen))
232		hdrlen += IPV4_BEET_PHMAXLEN - (optlen & 4);
233
234	skb_set_network_header(skb, -x->props.header_len - hdrlen +
235			       (XFRM_MODE_SKB_CB(skb)->ihl - sizeof(*top_iph)));
236	if (x->sel.family != AF_INET6)
237		skb->network_header += IPV4_BEET_PHMAXLEN;
238	skb->mac_header = skb->network_header +
239			  offsetof(struct iphdr, protocol);
240	skb->transport_header = skb->network_header + sizeof(*top_iph);
241
242	xfrm4_beet_make_header(skb);
243
244	ph = __skb_pull(skb, XFRM_MODE_SKB_CB(skb)->ihl - hdrlen);
245
246	top_iph = ip_hdr(skb);
247
248	if (unlikely(optlen)) {
249		if (WARN_ON(optlen < 0))
250			return -EINVAL;
251
252		ph->padlen = 4 - (optlen & 4);
253		ph->hdrlen = optlen / 8;
254		ph->nexthdr = top_iph->protocol;
255		if (ph->padlen)
256			memset(ph + 1, IPOPT_NOP, ph->padlen);
257
258		top_iph->protocol = IPPROTO_BEETPH;
259		top_iph->ihl = sizeof(struct iphdr) / 4;
260	}
261
262	top_iph->saddr = x->props.saddr.a4;
263	top_iph->daddr = x->id.daddr.a4;
264
265	return 0;
266}
267
268/* Add encapsulation header.
269 *
270 * The top IP header will be constructed per RFC 2401.
271 */
272static int xfrm4_tunnel_encap_add(struct xfrm_state *x, struct sk_buff *skb)
273{
274	bool small_ipv6 = (skb->protocol == htons(ETH_P_IPV6)) && (skb->len <= IPV6_MIN_MTU);
275	struct dst_entry *dst = skb_dst(skb);
276	struct iphdr *top_iph;
277	int flags;
278
279	skb_set_inner_network_header(skb, skb_network_offset(skb));
280	skb_set_inner_transport_header(skb, skb_transport_offset(skb));
281
282	skb_set_network_header(skb, -x->props.header_len);
283	skb->mac_header = skb->network_header +
284			  offsetof(struct iphdr, protocol);
285	skb->transport_header = skb->network_header + sizeof(*top_iph);
286	top_iph = ip_hdr(skb);
287
288	top_iph->ihl = 5;
289	top_iph->version = 4;
290
291	top_iph->protocol = xfrm_af2proto(skb_dst(skb)->ops->family);
292
293	/* DS disclosing depends on XFRM_SA_XFLAG_DONT_ENCAP_DSCP */
294	if (x->props.extra_flags & XFRM_SA_XFLAG_DONT_ENCAP_DSCP)
295		top_iph->tos = 0;
296	else
297		top_iph->tos = XFRM_MODE_SKB_CB(skb)->tos;
298	top_iph->tos = INET_ECN_encapsulate(top_iph->tos,
299					    XFRM_MODE_SKB_CB(skb)->tos);
300
301	flags = x->props.flags;
302	if (flags & XFRM_STATE_NOECN)
303		IP_ECN_clear(top_iph);
304
305	top_iph->frag_off = (flags & XFRM_STATE_NOPMTUDISC) || small_ipv6 ?
306		0 : (XFRM_MODE_SKB_CB(skb)->frag_off & htons(IP_DF));
307
308	top_iph->ttl = ip4_dst_hoplimit(xfrm_dst_child(dst));
309
310	top_iph->saddr = x->props.saddr.a4;
311	top_iph->daddr = x->id.daddr.a4;
312	ip_select_ident(dev_net(dst->dev), skb, NULL);
313
314	return 0;
315}
316
317#if IS_ENABLED(CONFIG_IPV6)
318static int xfrm6_tunnel_encap_add(struct xfrm_state *x, struct sk_buff *skb)
319{
320	struct dst_entry *dst = skb_dst(skb);
321	struct ipv6hdr *top_iph;
322	int dsfield;
323
324	skb_set_inner_network_header(skb, skb_network_offset(skb));
325	skb_set_inner_transport_header(skb, skb_transport_offset(skb));
326
327	skb_set_network_header(skb, -x->props.header_len);
328	skb->mac_header = skb->network_header +
329			  offsetof(struct ipv6hdr, nexthdr);
330	skb->transport_header = skb->network_header + sizeof(*top_iph);
331	top_iph = ipv6_hdr(skb);
332
333	top_iph->version = 6;
334
335	memcpy(top_iph->flow_lbl, XFRM_MODE_SKB_CB(skb)->flow_lbl,
336	       sizeof(top_iph->flow_lbl));
337	top_iph->nexthdr = xfrm_af2proto(skb_dst(skb)->ops->family);
338
339	if (x->props.extra_flags & XFRM_SA_XFLAG_DONT_ENCAP_DSCP)
340		dsfield = 0;
341	else
342		dsfield = XFRM_MODE_SKB_CB(skb)->tos;
343	dsfield = INET_ECN_encapsulate(dsfield, XFRM_MODE_SKB_CB(skb)->tos);
344	if (x->props.flags & XFRM_STATE_NOECN)
345		dsfield &= ~INET_ECN_MASK;
346	ipv6_change_dsfield(top_iph, 0, dsfield);
347	top_iph->hop_limit = ip6_dst_hoplimit(xfrm_dst_child(dst));
348	top_iph->saddr = *(struct in6_addr *)&x->props.saddr;
349	top_iph->daddr = *(struct in6_addr *)&x->id.daddr;
350	return 0;
351}
352
353static int xfrm6_beet_encap_add(struct xfrm_state *x, struct sk_buff *skb)
354{
355	struct ipv6hdr *top_iph;
356	struct ip_beet_phdr *ph;
357	int optlen, hdr_len;
358
359	hdr_len = 0;
360	optlen = XFRM_MODE_SKB_CB(skb)->optlen;
361	if (unlikely(optlen))
362		hdr_len += IPV4_BEET_PHMAXLEN - (optlen & 4);
363
364	skb_set_network_header(skb, -x->props.header_len - hdr_len);
365	if (x->sel.family != AF_INET6)
366		skb->network_header += IPV4_BEET_PHMAXLEN;
367	skb->mac_header = skb->network_header +
368			  offsetof(struct ipv6hdr, nexthdr);
369	skb->transport_header = skb->network_header + sizeof(*top_iph);
370	ph = __skb_pull(skb, XFRM_MODE_SKB_CB(skb)->ihl - hdr_len);
371
372	xfrm6_beet_make_header(skb);
373
374	top_iph = ipv6_hdr(skb);
375	if (unlikely(optlen)) {
376		if (WARN_ON(optlen < 0))
377			return -EINVAL;
378
379		ph->padlen = 4 - (optlen & 4);
380		ph->hdrlen = optlen / 8;
381		ph->nexthdr = top_iph->nexthdr;
382		if (ph->padlen)
383			memset(ph + 1, IPOPT_NOP, ph->padlen);
384
385		top_iph->nexthdr = IPPROTO_BEETPH;
386	}
387
388	top_iph->saddr = *(struct in6_addr *)&x->props.saddr;
389	top_iph->daddr = *(struct in6_addr *)&x->id.daddr;
390	return 0;
391}
392#endif
393
394/* Add encapsulation header.
395 *
396 * On exit, the transport header will be set to the start of the
397 * encapsulation header to be filled in by x->type->output and the mac
398 * header will be set to the nextheader (protocol for IPv4) field of the
399 * extension header directly preceding the encapsulation header, or in
400 * its absence, that of the top IP header.
401 * The value of the network header will always point to the top IP header
402 * while skb->data will point to the payload.
403 */
404static int xfrm4_prepare_output(struct xfrm_state *x, struct sk_buff *skb)
405{
406	int err;
407
408	err = xfrm_inner_extract_output(x, skb);
409	if (err)
410		return err;
411
412	IPCB(skb)->flags |= IPSKB_XFRM_TUNNEL_SIZE;
413	skb->protocol = htons(ETH_P_IP);
414
415	switch (x->outer_mode.encap) {
416	case XFRM_MODE_BEET:
417		return xfrm4_beet_encap_add(x, skb);
418	case XFRM_MODE_TUNNEL:
419		return xfrm4_tunnel_encap_add(x, skb);
420	}
421
422	WARN_ON_ONCE(1);
423	return -EOPNOTSUPP;
424}
425
426static int xfrm6_prepare_output(struct xfrm_state *x, struct sk_buff *skb)
427{
428#if IS_ENABLED(CONFIG_IPV6)
429	int err;
430
431	err = xfrm_inner_extract_output(x, skb);
432	if (err)
433		return err;
434
435	skb->ignore_df = 1;
436	skb->protocol = htons(ETH_P_IPV6);
437
438	switch (x->outer_mode.encap) {
439	case XFRM_MODE_BEET:
440		return xfrm6_beet_encap_add(x, skb);
441	case XFRM_MODE_TUNNEL:
442		return xfrm6_tunnel_encap_add(x, skb);
443	default:
444		WARN_ON_ONCE(1);
445		return -EOPNOTSUPP;
446	}
447#endif
448	WARN_ON_ONCE(1);
449	return -EAFNOSUPPORT;
450}
451
452static int xfrm_outer_mode_output(struct xfrm_state *x, struct sk_buff *skb)
453{
454	switch (x->outer_mode.encap) {
455	case XFRM_MODE_BEET:
456	case XFRM_MODE_TUNNEL:
457		if (x->outer_mode.family == AF_INET)
458			return xfrm4_prepare_output(x, skb);
459		if (x->outer_mode.family == AF_INET6)
460			return xfrm6_prepare_output(x, skb);
461		break;
462	case XFRM_MODE_TRANSPORT:
463		if (x->outer_mode.family == AF_INET)
464			return xfrm4_transport_output(x, skb);
465		if (x->outer_mode.family == AF_INET6)
466			return xfrm6_transport_output(x, skb);
467		break;
468	case XFRM_MODE_ROUTEOPTIMIZATION:
469		if (x->outer_mode.family == AF_INET6)
470			return xfrm6_ro_output(x, skb);
471		WARN_ON_ONCE(1);
472		break;
473	default:
474		WARN_ON_ONCE(1);
475		break;
476	}
477
478	return -EOPNOTSUPP;
479}
480
481#if IS_ENABLED(CONFIG_NET_PKTGEN)
482int pktgen_xfrm_outer_mode_output(struct xfrm_state *x, struct sk_buff *skb)
483{
484	return xfrm_outer_mode_output(x, skb);
485}
486EXPORT_SYMBOL_GPL(pktgen_xfrm_outer_mode_output);
487#endif
488
489static int xfrm_output_one(struct sk_buff *skb, int err)
490{
491	struct dst_entry *dst = skb_dst(skb);
492	struct xfrm_state *x = dst->xfrm;
493	struct net *net = xs_net(x);
494
495	if (err <= 0 || x->xso.type == XFRM_DEV_OFFLOAD_PACKET)
496		goto resume;
497
498	do {
499		err = xfrm_skb_check_space(skb);
500		if (err) {
501			XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTERROR);
502			goto error_nolock;
503		}
504
505		skb->mark = xfrm_smark_get(skb->mark, x);
506
507		err = xfrm_outer_mode_output(x, skb);
508		if (err) {
509			XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATEMODEERROR);
510			goto error_nolock;
511		}
512
513		spin_lock_bh(&x->lock);
514
515		if (unlikely(x->km.state != XFRM_STATE_VALID)) {
516			XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATEINVALID);
517			err = -EINVAL;
518			goto error;
519		}
520
521		err = xfrm_state_check_expire(x);
522		if (err) {
523			XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATEEXPIRED);
524			goto error;
525		}
526
527		err = xfrm_replay_overflow(x, skb);
528		if (err) {
529			XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATESEQERROR);
530			goto error;
531		}
532
533		x->curlft.bytes += skb->len;
534		x->curlft.packets++;
535		x->lastused = ktime_get_real_seconds();
536
537		spin_unlock_bh(&x->lock);
538
539		skb_dst_force(skb);
540		if (!skb_dst(skb)) {
541			XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTERROR);
542			err = -EHOSTUNREACH;
543			goto error_nolock;
544		}
545
546		if (xfrm_offload(skb)) {
547			x->type_offload->encap(x, skb);
548		} else {
549			/* Inner headers are invalid now. */
550			skb->encapsulation = 0;
551
552			err = x->type->output(x, skb);
553			if (err == -EINPROGRESS)
554				goto out;
555		}
556
557resume:
558		if (err) {
559			XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATEPROTOERROR);
560			goto error_nolock;
561		}
562
563		dst = skb_dst_pop(skb);
564		if (!dst) {
565			XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTERROR);
566			err = -EHOSTUNREACH;
567			goto error_nolock;
568		}
569		skb_dst_set(skb, dst);
570		x = dst->xfrm;
571	} while (x && !(x->outer_mode.flags & XFRM_MODE_FLAG_TUNNEL));
572
573	return 0;
574
 
 
575error:
576	spin_unlock_bh(&x->lock);
577error_nolock:
578	kfree_skb(skb);
579out:
580	return err;
581}
582
583int xfrm_output_resume(struct sock *sk, struct sk_buff *skb, int err)
584{
585	struct net *net = xs_net(skb_dst(skb)->xfrm);
586
587	while (likely((err = xfrm_output_one(skb, err)) == 0)) {
588		nf_reset_ct(skb);
589
590		err = skb_dst(skb)->ops->local_out(net, sk, skb);
591		if (unlikely(err != 1))
592			goto out;
593
594		if (!skb_dst(skb)->xfrm)
595			return dst_output(net, sk, skb);
596
597		err = nf_hook(skb_dst(skb)->ops->family,
598			      NF_INET_POST_ROUTING, net, sk, skb,
599			      NULL, skb_dst(skb)->dev, xfrm_output2);
600		if (unlikely(err != 1))
601			goto out;
602	}
603
604	if (err == -EINPROGRESS)
605		err = 0;
606
607out:
608	return err;
609}
610EXPORT_SYMBOL_GPL(xfrm_output_resume);
611
612static int xfrm_output2(struct net *net, struct sock *sk, struct sk_buff *skb)
613{
614	return xfrm_output_resume(sk, skb, 1);
615}
616
617static int xfrm_output_gso(struct net *net, struct sock *sk, struct sk_buff *skb)
618{
619	struct sk_buff *segs, *nskb;
620
621	BUILD_BUG_ON(sizeof(*IPCB(skb)) > SKB_GSO_CB_OFFSET);
622	BUILD_BUG_ON(sizeof(*IP6CB(skb)) > SKB_GSO_CB_OFFSET);
623	segs = skb_gso_segment(skb, 0);
624	kfree_skb(skb);
625	if (IS_ERR(segs))
626		return PTR_ERR(segs);
627	if (segs == NULL)
628		return -EINVAL;
629
630	skb_list_walk_safe(segs, segs, nskb) {
 
631		int err;
632
633		skb_mark_not_on_list(segs);
634		err = xfrm_output2(net, sk, segs);
635
636		if (unlikely(err)) {
637			kfree_skb_list(nskb);
 
 
 
 
638			return err;
639		}
640	}
641
642	return 0;
643}
644
645/* For partial checksum offload, the outer header checksum is calculated
646 * by software and the inner header checksum is calculated by hardware.
647 * This requires hardware to know the inner packet type to calculate
648 * the inner header checksum. Save inner ip protocol here to avoid
649 * traversing the packet in the vendor's xmit code.
650 * For IPsec tunnel mode save the ip protocol from the IP header of the
651 * plain text packet. Otherwise If the encap type is IPIP, just save
652 * skb->inner_ipproto in any other case get the ip protocol from the IP
653 * header.
654 */
655static void xfrm_get_inner_ipproto(struct sk_buff *skb, struct xfrm_state *x)
656{
657	struct xfrm_offload *xo = xfrm_offload(skb);
658	const struct ethhdr *eth;
659
660	if (!xo)
661		return;
662
663	if (x->outer_mode.encap == XFRM_MODE_TUNNEL) {
664		switch (x->outer_mode.family) {
665		case AF_INET:
666			xo->inner_ipproto = ip_hdr(skb)->protocol;
667			break;
668		case AF_INET6:
669			xo->inner_ipproto = ipv6_hdr(skb)->nexthdr;
670			break;
671		default:
672			break;
673		}
674
675		return;
676	}
677
678	/* non-Tunnel Mode */
679	if (!skb->encapsulation)
680		return;
681
682	if (skb->inner_protocol_type == ENCAP_TYPE_IPPROTO) {
683		xo->inner_ipproto = skb->inner_ipproto;
684		return;
685	}
686
687	if (skb->inner_protocol_type != ENCAP_TYPE_ETHER)
688		return;
689
690	eth = (struct ethhdr *)skb_inner_mac_header(skb);
691
692	switch (ntohs(eth->h_proto)) {
693	case ETH_P_IPV6:
694		xo->inner_ipproto = inner_ipv6_hdr(skb)->nexthdr;
695		break;
696	case ETH_P_IP:
697		xo->inner_ipproto = inner_ip_hdr(skb)->protocol;
698		break;
699	}
700}
701
702int xfrm_output(struct sock *sk, struct sk_buff *skb)
703{
704	struct net *net = dev_net(skb_dst(skb)->dev);
705	struct xfrm_state *x = skb_dst(skb)->xfrm;
706	int err;
707
708	switch (x->outer_mode.family) {
709	case AF_INET:
710		memset(IPCB(skb), 0, sizeof(*IPCB(skb)));
711		IPCB(skb)->flags |= IPSKB_XFRM_TRANSFORMED;
712		break;
713	case AF_INET6:
714		memset(IP6CB(skb), 0, sizeof(*IP6CB(skb)));
715
716		IP6CB(skb)->flags |= IP6SKB_XFRM_TRANSFORMED;
717		break;
718	}
719
720	if (x->xso.type == XFRM_DEV_OFFLOAD_PACKET) {
721		if (!xfrm_dev_offload_ok(skb, x)) {
722			XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTERROR);
723			kfree_skb(skb);
724			return -EHOSTUNREACH;
725		}
726
727		return xfrm_output_resume(sk, skb, 0);
728	}
729
730	secpath_reset(skb);
731
732	if (xfrm_dev_offload_ok(skb, x)) {
733		struct sec_path *sp;
734
735		sp = secpath_set(skb);
736		if (!sp) {
737			XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTERROR);
738			kfree_skb(skb);
739			return -ENOMEM;
740		}
741
742		sp->olen++;
743		sp->xvec[sp->len++] = x;
744		xfrm_state_hold(x);
745
746		xfrm_get_inner_ipproto(skb, x);
747		skb->encapsulation = 1;
748
749		if (skb_is_gso(skb)) {
750			if (skb->inner_protocol)
751				return xfrm_output_gso(net, sk, skb);
752
753			skb_shinfo(skb)->gso_type |= SKB_GSO_ESP;
754			goto out;
755		}
756
757		if (x->xso.dev && x->xso.dev->features & NETIF_F_HW_ESP_TX_CSUM)
758			goto out;
759	} else {
760		if (skb_is_gso(skb))
761			return xfrm_output_gso(net, sk, skb);
762	}
763
764	if (skb->ip_summed == CHECKSUM_PARTIAL) {
765		err = skb_checksum_help(skb);
766		if (err) {
767			XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTERROR);
768			kfree_skb(skb);
769			return err;
770		}
771	}
772
773out:
774	return xfrm_output2(net, sk, skb);
775}
776EXPORT_SYMBOL_GPL(xfrm_output);
777
778static int xfrm4_tunnel_check_size(struct sk_buff *skb)
779{
780	int mtu, ret = 0;
781
782	if (IPCB(skb)->flags & IPSKB_XFRM_TUNNEL_SIZE)
783		goto out;
784
785	if (!(ip_hdr(skb)->frag_off & htons(IP_DF)) || skb->ignore_df)
786		goto out;
787
788	mtu = dst_mtu(skb_dst(skb));
789	if ((!skb_is_gso(skb) && skb->len > mtu) ||
790	    (skb_is_gso(skb) &&
791	     !skb_gso_validate_network_len(skb, ip_skb_dst_mtu(skb->sk, skb)))) {
792		skb->protocol = htons(ETH_P_IP);
793
794		if (skb->sk)
795			xfrm_local_error(skb, mtu);
796		else
797			icmp_send(skb, ICMP_DEST_UNREACH,
798				  ICMP_FRAG_NEEDED, htonl(mtu));
799		ret = -EMSGSIZE;
800	}
801out:
802	return ret;
803}
804
805static int xfrm4_extract_output(struct xfrm_state *x, struct sk_buff *skb)
806{
807	int err;
808
809	if (x->outer_mode.encap == XFRM_MODE_BEET &&
810	    ip_is_fragment(ip_hdr(skb))) {
811		net_warn_ratelimited("BEET mode doesn't support inner IPv4 fragments\n");
812		return -EAFNOSUPPORT;
813	}
814
815	err = xfrm4_tunnel_check_size(skb);
816	if (err)
817		return err;
818
819	XFRM_MODE_SKB_CB(skb)->protocol = ip_hdr(skb)->protocol;
820
821	xfrm4_extract_header(skb);
822	return 0;
823}
824
825#if IS_ENABLED(CONFIG_IPV6)
826static int xfrm6_tunnel_check_size(struct sk_buff *skb)
827{
828	int mtu, ret = 0;
829	struct dst_entry *dst = skb_dst(skb);
830
831	if (skb->ignore_df)
832		goto out;
833
834	mtu = dst_mtu(dst);
835	if (mtu < IPV6_MIN_MTU)
836		mtu = IPV6_MIN_MTU;
837
838	if ((!skb_is_gso(skb) && skb->len > mtu) ||
839	    (skb_is_gso(skb) &&
840	     !skb_gso_validate_network_len(skb, ip6_skb_dst_mtu(skb)))) {
841		skb->dev = dst->dev;
842		skb->protocol = htons(ETH_P_IPV6);
843
844		if (xfrm6_local_dontfrag(skb->sk))
845			ipv6_stub->xfrm6_local_rxpmtu(skb, mtu);
846		else if (skb->sk)
847			xfrm_local_error(skb, mtu);
848		else
849			icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu);
850		ret = -EMSGSIZE;
851	}
852out:
853	return ret;
854}
855#endif
856
857static int xfrm6_extract_output(struct xfrm_state *x, struct sk_buff *skb)
858{
859#if IS_ENABLED(CONFIG_IPV6)
860	int err;
861
862	err = xfrm6_tunnel_check_size(skb);
863	if (err)
864		return err;
865
866	XFRM_MODE_SKB_CB(skb)->protocol = ipv6_hdr(skb)->nexthdr;
867
868	xfrm6_extract_header(skb);
869	return 0;
870#else
871	WARN_ON_ONCE(1);
872	return -EAFNOSUPPORT;
873#endif
874}
875
876static int xfrm_inner_extract_output(struct xfrm_state *x, struct sk_buff *skb)
877{
878	const struct xfrm_mode *inner_mode;
879
880	if (x->sel.family == AF_UNSPEC)
881		inner_mode = xfrm_ip2inner_mode(x,
882				xfrm_af2proto(skb_dst(skb)->ops->family));
883	else
884		inner_mode = &x->inner_mode;
885
886	if (inner_mode == NULL)
887		return -EAFNOSUPPORT;
888
889	switch (inner_mode->family) {
890	case AF_INET:
891		return xfrm4_extract_output(x, skb);
892	case AF_INET6:
893		return xfrm6_extract_output(x, skb);
894	}
895
896	return -EAFNOSUPPORT;
897}
898
899void xfrm_local_error(struct sk_buff *skb, int mtu)
900{
901	unsigned int proto;
902	struct xfrm_state_afinfo *afinfo;
903
904	if (skb->protocol == htons(ETH_P_IP))
905		proto = AF_INET;
906	else if (skb->protocol == htons(ETH_P_IPV6) &&
907		 skb->sk->sk_family == AF_INET6)
908		proto = AF_INET6;
909	else
910		return;
911
912	afinfo = xfrm_state_get_afinfo(proto);
913	if (afinfo) {
914		afinfo->local_error(skb, mtu);
915		rcu_read_unlock();
916	}
917}
918EXPORT_SYMBOL_GPL(xfrm_local_error);