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/gso.h>
17#include <net/icmp.h>
18#include <net/inet_ecn.h>
19#include <net/xfrm.h>
20
21#if IS_ENABLED(CONFIG_IPV6)
22#include <net/ip6_route.h>
23#include <net/ipv6_stubs.h>
24#endif
25
26#include "xfrm_inout.h"
27
28static int xfrm_output2(struct net *net, struct sock *sk, struct sk_buff *skb);
29static int xfrm_inner_extract_output(struct xfrm_state *x, struct sk_buff *skb);
30
31static int xfrm_skb_check_space(struct sk_buff *skb)
32{
33	struct dst_entry *dst = skb_dst(skb);
34	int nhead = dst->header_len + LL_RESERVED_SPACE(dst->dev)
35		- skb_headroom(skb);
36	int ntail = dst->dev->needed_tailroom - skb_tailroom(skb);
37
38	if (nhead <= 0) {
39		if (ntail <= 0)
40			return 0;
41		nhead = 0;
42	} else if (ntail < 0)
43		ntail = 0;
44
45	return pskb_expand_head(skb, nhead, ntail, GFP_ATOMIC);
46}
47
48/* Children define the path of the packet through the
49 * Linux networking.  Thus, destinations are stackable.
50 */
51
52static struct dst_entry *skb_dst_pop(struct sk_buff *skb)
53{
54	struct dst_entry *child = dst_clone(xfrm_dst_child(skb_dst(skb)));
55
56	skb_dst_drop(skb);
57	return child;
58}
59
60/* Add encapsulation header.
61 *
62 * The IP header will be moved forward to make space for the encapsulation
63 * header.
64 */
65static int xfrm4_transport_output(struct xfrm_state *x, struct sk_buff *skb)
66{
67	struct iphdr *iph = ip_hdr(skb);
68	int ihl = iph->ihl * 4;
69
70	skb_set_inner_transport_header(skb, skb_transport_offset(skb));
71
72	skb_set_network_header(skb, -x->props.header_len);
73	skb->mac_header = skb->network_header +
74			  offsetof(struct iphdr, protocol);
75	skb->transport_header = skb->network_header + ihl;
76	__skb_pull(skb, ihl);
77	memmove(skb_network_header(skb), iph, ihl);
78	return 0;
79}
80
81#if IS_ENABLED(CONFIG_IPV6_MIP6)
82static int mip6_rthdr_offset(struct sk_buff *skb, u8 **nexthdr, int type)
83{
84	const unsigned char *nh = skb_network_header(skb);
85	unsigned int offset = sizeof(struct ipv6hdr);
86	unsigned int packet_len;
87	int found_rhdr = 0;
88
89	packet_len = skb_tail_pointer(skb) - nh;
90	*nexthdr = &ipv6_hdr(skb)->nexthdr;
91
92	while (offset <= packet_len) {
93		struct ipv6_opt_hdr *exthdr;
94
95		switch (**nexthdr) {
96		case NEXTHDR_HOP:
97			break;
98		case NEXTHDR_ROUTING:
99			if (type == IPPROTO_ROUTING && offset + 3 <= packet_len) {
100				struct ipv6_rt_hdr *rt;
101
102				rt = (struct ipv6_rt_hdr *)(nh + offset);
103				if (rt->type != 0)
104					return offset;
105			}
106			found_rhdr = 1;
107			break;
108		case NEXTHDR_DEST:
109			/* HAO MUST NOT appear more than once.
110			 * XXX: It is better to try to find by the end of
111			 * XXX: packet if HAO exists.
112			 */
113			if (ipv6_find_tlv(skb, offset, IPV6_TLV_HAO) >= 0) {
114				net_dbg_ratelimited("mip6: hao exists already, override\n");
115				return offset;
116			}
117
118			if (found_rhdr)
119				return offset;
120
121			break;
122		default:
123			return offset;
124		}
125
126		if (offset + sizeof(struct ipv6_opt_hdr) > packet_len)
127			return -EINVAL;
128
129		exthdr = (struct ipv6_opt_hdr *)(skb_network_header(skb) +
130						 offset);
131		offset += ipv6_optlen(exthdr);
132		if (offset > IPV6_MAXPLEN)
133			return -EINVAL;
134		*nexthdr = &exthdr->nexthdr;
135	}
136
137	return -EINVAL;
138}
139#endif
140
141#if IS_ENABLED(CONFIG_IPV6)
142static int xfrm6_hdr_offset(struct xfrm_state *x, struct sk_buff *skb, u8 **prevhdr)
143{
144	switch (x->type->proto) {
145#if IS_ENABLED(CONFIG_IPV6_MIP6)
146	case IPPROTO_DSTOPTS:
147	case IPPROTO_ROUTING:
148		return mip6_rthdr_offset(skb, prevhdr, x->type->proto);
149#endif
150	default:
151		break;
152	}
153
154	return ip6_find_1stfragopt(skb, prevhdr);
155}
156#endif
157
158/* Add encapsulation header.
159 *
160 * The IP header and mutable extension headers will be moved forward to make
161 * space for the encapsulation header.
162 */
163static int xfrm6_transport_output(struct xfrm_state *x, struct sk_buff *skb)
164{
165#if IS_ENABLED(CONFIG_IPV6)
166	struct ipv6hdr *iph;
167	u8 *prevhdr;
168	int hdr_len;
169
170	iph = ipv6_hdr(skb);
171	skb_set_inner_transport_header(skb, skb_transport_offset(skb));
172
173	hdr_len = xfrm6_hdr_offset(x, skb, &prevhdr);
174	if (hdr_len < 0)
175		return hdr_len;
176	skb_set_mac_header(skb,
177			   (prevhdr - x->props.header_len) - skb->data);
178	skb_set_network_header(skb, -x->props.header_len);
179	skb->transport_header = skb->network_header + hdr_len;
180	__skb_pull(skb, hdr_len);
181	memmove(ipv6_hdr(skb), iph, hdr_len);
182	return 0;
183#else
184	WARN_ON_ONCE(1);
185	return -EAFNOSUPPORT;
186#endif
187}
188
189/* Add route optimization header space.
190 *
191 * The IP header and mutable extension headers will be moved forward to make
192 * space for the route optimization header.
193 */
194static int xfrm6_ro_output(struct xfrm_state *x, struct sk_buff *skb)
195{
196#if IS_ENABLED(CONFIG_IPV6)
197	struct ipv6hdr *iph;
198	u8 *prevhdr;
199	int hdr_len;
200
201	iph = ipv6_hdr(skb);
202
203	hdr_len = xfrm6_hdr_offset(x, skb, &prevhdr);
204	if (hdr_len < 0)
205		return hdr_len;
206	skb_set_mac_header(skb,
207			   (prevhdr - x->props.header_len) - skb->data);
208	skb_set_network_header(skb, -x->props.header_len);
209	skb->transport_header = skb->network_header + hdr_len;
210	__skb_pull(skb, hdr_len);
211	memmove(ipv6_hdr(skb), iph, hdr_len);
212
213	return 0;
214#else
215	WARN_ON_ONCE(1);
216	return -EAFNOSUPPORT;
217#endif
218}
219
220/* Add encapsulation header.
221 *
222 * The top IP header will be constructed per draft-nikander-esp-beet-mode-06.txt.
223 */
224static int xfrm4_beet_encap_add(struct xfrm_state *x, struct sk_buff *skb)
225{
226	struct ip_beet_phdr *ph;
227	struct iphdr *top_iph;
228	int hdrlen, optlen;
229
230	hdrlen = 0;
231	optlen = XFRM_MODE_SKB_CB(skb)->optlen;
232	if (unlikely(optlen))
233		hdrlen += IPV4_BEET_PHMAXLEN - (optlen & 4);
234
235	skb_set_network_header(skb, -x->props.header_len - hdrlen +
236			       (XFRM_MODE_SKB_CB(skb)->ihl - sizeof(*top_iph)));
237	if (x->sel.family != AF_INET6)
238		skb->network_header += IPV4_BEET_PHMAXLEN;
239	skb->mac_header = skb->network_header +
240			  offsetof(struct iphdr, protocol);
241	skb->transport_header = skb->network_header + sizeof(*top_iph);
242
243	xfrm4_beet_make_header(skb);
244
245	ph = __skb_pull(skb, XFRM_MODE_SKB_CB(skb)->ihl - hdrlen);
246
247	top_iph = ip_hdr(skb);
248
249	if (unlikely(optlen)) {
250		if (WARN_ON(optlen < 0))
251			return -EINVAL;
252
253		ph->padlen = 4 - (optlen & 4);
254		ph->hdrlen = optlen / 8;
255		ph->nexthdr = top_iph->protocol;
256		if (ph->padlen)
257			memset(ph + 1, IPOPT_NOP, ph->padlen);
258
259		top_iph->protocol = IPPROTO_BEETPH;
260		top_iph->ihl = sizeof(struct iphdr) / 4;
261	}
262
263	top_iph->saddr = x->props.saddr.a4;
264	top_iph->daddr = x->id.daddr.a4;
265
266	return 0;
267}
268
269/* Add encapsulation header.
270 *
271 * The top IP header will be constructed per RFC 2401.
272 */
273static int xfrm4_tunnel_encap_add(struct xfrm_state *x, struct sk_buff *skb)
274{
275	bool small_ipv6 = (skb->protocol == htons(ETH_P_IPV6)) && (skb->len <= IPV6_MIN_MTU);
276	struct dst_entry *dst = skb_dst(skb);
277	struct iphdr *top_iph;
278	int flags;
279
280	skb_set_inner_network_header(skb, skb_network_offset(skb));
281	skb_set_inner_transport_header(skb, skb_transport_offset(skb));
282
283	skb_set_network_header(skb, -x->props.header_len);
284	skb->mac_header = skb->network_header +
285			  offsetof(struct iphdr, protocol);
286	skb->transport_header = skb->network_header + sizeof(*top_iph);
287	top_iph = ip_hdr(skb);
288
289	top_iph->ihl = 5;
290	top_iph->version = 4;
291
292	top_iph->protocol = xfrm_af2proto(skb_dst(skb)->ops->family);
293
294	/* DS disclosing depends on XFRM_SA_XFLAG_DONT_ENCAP_DSCP */
295	if (x->props.extra_flags & XFRM_SA_XFLAG_DONT_ENCAP_DSCP)
296		top_iph->tos = 0;
297	else
298		top_iph->tos = XFRM_MODE_SKB_CB(skb)->tos;
299	top_iph->tos = INET_ECN_encapsulate(top_iph->tos,
300					    XFRM_MODE_SKB_CB(skb)->tos);
301
302	flags = x->props.flags;
303	if (flags & XFRM_STATE_NOECN)
304		IP_ECN_clear(top_iph);
305
306	top_iph->frag_off = (flags & XFRM_STATE_NOPMTUDISC) || small_ipv6 ?
307		0 : (XFRM_MODE_SKB_CB(skb)->frag_off & htons(IP_DF));
308
309	top_iph->ttl = ip4_dst_hoplimit(xfrm_dst_child(dst));
310
311	top_iph->saddr = x->props.saddr.a4;
312	top_iph->daddr = x->id.daddr.a4;
313	ip_select_ident(dev_net(dst->dev), skb, NULL);
314
315	return 0;
316}
317
318#if IS_ENABLED(CONFIG_IPV6)
319static int xfrm6_tunnel_encap_add(struct xfrm_state *x, struct sk_buff *skb)
320{
321	struct dst_entry *dst = skb_dst(skb);
322	struct ipv6hdr *top_iph;
323	int dsfield;
324
325	skb_set_inner_network_header(skb, skb_network_offset(skb));
326	skb_set_inner_transport_header(skb, skb_transport_offset(skb));
327
328	skb_set_network_header(skb, -x->props.header_len);
329	skb->mac_header = skb->network_header +
330			  offsetof(struct ipv6hdr, nexthdr);
331	skb->transport_header = skb->network_header + sizeof(*top_iph);
332	top_iph = ipv6_hdr(skb);
333
334	top_iph->version = 6;
335
336	memcpy(top_iph->flow_lbl, XFRM_MODE_SKB_CB(skb)->flow_lbl,
337	       sizeof(top_iph->flow_lbl));
338	top_iph->nexthdr = xfrm_af2proto(skb_dst(skb)->ops->family);
339
340	if (x->props.extra_flags & XFRM_SA_XFLAG_DONT_ENCAP_DSCP)
341		dsfield = 0;
342	else
343		dsfield = XFRM_MODE_SKB_CB(skb)->tos;
344	dsfield = INET_ECN_encapsulate(dsfield, XFRM_MODE_SKB_CB(skb)->tos);
345	if (x->props.flags & XFRM_STATE_NOECN)
346		dsfield &= ~INET_ECN_MASK;
347	ipv6_change_dsfield(top_iph, 0, dsfield);
348	top_iph->hop_limit = ip6_dst_hoplimit(xfrm_dst_child(dst));
349	top_iph->saddr = *(struct in6_addr *)&x->props.saddr;
350	top_iph->daddr = *(struct in6_addr *)&x->id.daddr;
351	return 0;
352}
353
354static int xfrm6_beet_encap_add(struct xfrm_state *x, struct sk_buff *skb)
355{
356	struct ipv6hdr *top_iph;
357	struct ip_beet_phdr *ph;
358	int optlen, hdr_len;
359
360	hdr_len = 0;
361	optlen = XFRM_MODE_SKB_CB(skb)->optlen;
362	if (unlikely(optlen))
363		hdr_len += IPV4_BEET_PHMAXLEN - (optlen & 4);
364
365	skb_set_network_header(skb, -x->props.header_len - hdr_len);
366	if (x->sel.family != AF_INET6)
367		skb->network_header += IPV4_BEET_PHMAXLEN;
368	skb->mac_header = skb->network_header +
369			  offsetof(struct ipv6hdr, nexthdr);
370	skb->transport_header = skb->network_header + sizeof(*top_iph);
371	ph = __skb_pull(skb, XFRM_MODE_SKB_CB(skb)->ihl - hdr_len);
372
373	xfrm6_beet_make_header(skb);
374
375	top_iph = ipv6_hdr(skb);
376	if (unlikely(optlen)) {
377		if (WARN_ON(optlen < 0))
378			return -EINVAL;
379
380		ph->padlen = 4 - (optlen & 4);
381		ph->hdrlen = optlen / 8;
382		ph->nexthdr = top_iph->nexthdr;
383		if (ph->padlen)
384			memset(ph + 1, IPOPT_NOP, ph->padlen);
385
386		top_iph->nexthdr = IPPROTO_BEETPH;
387	}
388
389	top_iph->saddr = *(struct in6_addr *)&x->props.saddr;
390	top_iph->daddr = *(struct in6_addr *)&x->id.daddr;
391	return 0;
392}
393#endif
394
395/* Add encapsulation header.
396 *
397 * On exit, the transport header will be set to the start of the
398 * encapsulation header to be filled in by x->type->output and the mac
399 * header will be set to the nextheader (protocol for IPv4) field of the
400 * extension header directly preceding the encapsulation header, or in
401 * its absence, that of the top IP header.
402 * The value of the network header will always point to the top IP header
403 * while skb->data will point to the payload.
404 */
405static int xfrm4_prepare_output(struct xfrm_state *x, struct sk_buff *skb)
406{
407	int err;
408
409	err = xfrm_inner_extract_output(x, skb);
410	if (err)
411		return err;
412
413	IPCB(skb)->flags |= IPSKB_XFRM_TUNNEL_SIZE;
414	skb->protocol = htons(ETH_P_IP);
415
416	switch (x->props.mode) {
417	case XFRM_MODE_BEET:
418		return xfrm4_beet_encap_add(x, skb);
419	case XFRM_MODE_TUNNEL:
420		return xfrm4_tunnel_encap_add(x, skb);
421	}
422
423	WARN_ON_ONCE(1);
424	return -EOPNOTSUPP;
425}
426
427static int xfrm6_prepare_output(struct xfrm_state *x, struct sk_buff *skb)
428{
429#if IS_ENABLED(CONFIG_IPV6)
430	int err;
431
432	err = xfrm_inner_extract_output(x, skb);
433	if (err)
434		return err;
435
436	skb->ignore_df = 1;
437	skb->protocol = htons(ETH_P_IPV6);
438
439	switch (x->props.mode) {
440	case XFRM_MODE_BEET:
441		return xfrm6_beet_encap_add(x, skb);
442	case XFRM_MODE_TUNNEL:
443		return xfrm6_tunnel_encap_add(x, skb);
444	default:
445		WARN_ON_ONCE(1);
446		return -EOPNOTSUPP;
447	}
448#endif
449	WARN_ON_ONCE(1);
450	return -EAFNOSUPPORT;
451}
452
453static int xfrm_outer_mode_output(struct xfrm_state *x, struct sk_buff *skb)
454{
455	switch (x->props.mode) {
456	case XFRM_MODE_BEET:
457	case XFRM_MODE_TUNNEL:
458		if (x->props.family == AF_INET)
459			return xfrm4_prepare_output(x, skb);
460		if (x->props.family == AF_INET6)
461			return xfrm6_prepare_output(x, skb);
462		break;
463	case XFRM_MODE_TRANSPORT:
464		if (x->props.family == AF_INET)
465			return xfrm4_transport_output(x, skb);
466		if (x->props.family == AF_INET6)
467			return xfrm6_transport_output(x, skb);
468		break;
469	case XFRM_MODE_ROUTEOPTIMIZATION:
470		if (x->props.family == AF_INET6)
471			return xfrm6_ro_output(x, skb);
472		WARN_ON_ONCE(1);
473		break;
474	default:
475		WARN_ON_ONCE(1);
476		break;
477	}
478
479	return -EOPNOTSUPP;
480}
481
482#if IS_ENABLED(CONFIG_NET_PKTGEN)
483int pktgen_xfrm_outer_mode_output(struct xfrm_state *x, struct sk_buff *skb)
484{
485	return xfrm_outer_mode_output(x, skb);
486}
487EXPORT_SYMBOL_GPL(pktgen_xfrm_outer_mode_output);
488#endif
489
490static int xfrm_output_one(struct sk_buff *skb, int err)
491{
492	struct dst_entry *dst = skb_dst(skb);
493	struct xfrm_state *x = dst->xfrm;
494	struct net *net = xs_net(x);
495
496	if (err <= 0 || x->xso.type == XFRM_DEV_OFFLOAD_PACKET)
497		goto resume;
498
499	do {
500		err = xfrm_skb_check_space(skb);
501		if (err) {
502			XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTERROR);
503			goto error_nolock;
504		}
505
506		skb->mark = xfrm_smark_get(skb->mark, x);
507
508		err = xfrm_outer_mode_output(x, skb);
509		if (err) {
510			XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATEMODEERROR);
511			goto error_nolock;
512		}
513
514		spin_lock_bh(&x->lock);
515
516		if (unlikely(x->km.state != XFRM_STATE_VALID)) {
517			XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATEINVALID);
518			err = -EINVAL;
519			goto error;
520		}
521
522		err = xfrm_state_check_expire(x);
523		if (err) {
524			XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATEEXPIRED);
525			goto error;
526		}
527
528		err = xfrm_replay_overflow(x, skb);
529		if (err) {
530			XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATESEQERROR);
531			goto error;
532		}
533
534		x->curlft.bytes += skb->len;
535		x->curlft.packets++;
536		x->lastused = ktime_get_real_seconds();
537
538		spin_unlock_bh(&x->lock);
539
540		skb_dst_force(skb);
541		if (!skb_dst(skb)) {
542			XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTERROR);
543			err = -EHOSTUNREACH;
544			goto error_nolock;
545		}
546
547		if (xfrm_offload(skb)) {
548			x->type_offload->encap(x, skb);
549		} else {
550			/* Inner headers are invalid now. */
551			skb->encapsulation = 0;
552
553			err = x->type->output(x, skb);
554			if (err == -EINPROGRESS)
555				goto out;
556		}
557
558resume:
559		if (err) {
560			XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATEPROTOERROR);
561			goto error_nolock;
562		}
563
564		dst = skb_dst_pop(skb);
565		if (!dst) {
566			XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTERROR);
567			err = -EHOSTUNREACH;
568			goto error_nolock;
569		}
570		skb_dst_set(skb, dst);
571		x = dst->xfrm;
572	} while (x && !(x->outer_mode.flags & XFRM_MODE_FLAG_TUNNEL));
573
574	return 0;
575
576error:
577	spin_unlock_bh(&x->lock);
578error_nolock:
579	kfree_skb(skb);
580out:
581	return err;
582}
583
584int xfrm_output_resume(struct sock *sk, struct sk_buff *skb, int err)
585{
586	struct net *net = xs_net(skb_dst(skb)->xfrm);
587
588	while (likely((err = xfrm_output_one(skb, err)) == 0)) {
589		nf_reset_ct(skb);
590
591		err = skb_dst(skb)->ops->local_out(net, sk, skb);
592		if (unlikely(err != 1))
593			goto out;
594
595		if (!skb_dst(skb)->xfrm)
596			return dst_output(net, sk, skb);
597
598		err = nf_hook(skb_dst(skb)->ops->family,
599			      NF_INET_POST_ROUTING, net, sk, skb,
600			      NULL, skb_dst(skb)->dev, xfrm_output2);
601		if (unlikely(err != 1))
602			goto out;
603	}
604
605	if (err == -EINPROGRESS)
606		err = 0;
607
608out:
609	return err;
610}
611EXPORT_SYMBOL_GPL(xfrm_output_resume);
612
613static int xfrm_output2(struct net *net, struct sock *sk, struct sk_buff *skb)
614{
615	return xfrm_output_resume(sk, skb, 1);
616}
617
618static int xfrm_output_gso(struct net *net, struct sock *sk, struct sk_buff *skb)
619{
620	struct sk_buff *segs, *nskb;
621
622	BUILD_BUG_ON(sizeof(*IPCB(skb)) > SKB_GSO_CB_OFFSET);
623	BUILD_BUG_ON(sizeof(*IP6CB(skb)) > SKB_GSO_CB_OFFSET);
624	segs = skb_gso_segment(skb, 0);
625	kfree_skb(skb);
626	if (IS_ERR(segs))
627		return PTR_ERR(segs);
628	if (segs == NULL)
629		return -EINVAL;
630
631	skb_list_walk_safe(segs, segs, nskb) {
632		int err;
633
634		skb_mark_not_on_list(segs);
635		err = xfrm_output2(net, sk, segs);
636
637		if (unlikely(err)) {
638			kfree_skb_list(nskb);
639			return err;
640		}
641	}
642
643	return 0;
644}
645
646/* For partial checksum offload, the outer header checksum is calculated
647 * by software and the inner header checksum is calculated by hardware.
648 * This requires hardware to know the inner packet type to calculate
649 * the inner header checksum. Save inner ip protocol here to avoid
650 * traversing the packet in the vendor's xmit code.
651 * For IPsec tunnel mode save the ip protocol from the IP header of the
652 * plain text packet. Otherwise If the encap type is IPIP, just save
653 * skb->inner_ipproto in any other case get the ip protocol from the IP
654 * header.
655 */
656static void xfrm_get_inner_ipproto(struct sk_buff *skb, struct xfrm_state *x)
657{
658	struct xfrm_offload *xo = xfrm_offload(skb);
659	const struct ethhdr *eth;
660
661	if (!xo)
662		return;
663
664	if (x->outer_mode.encap == XFRM_MODE_TUNNEL) {
665		switch (x->outer_mode.family) {
666		case AF_INET:
667			xo->inner_ipproto = ip_hdr(skb)->protocol;
668			break;
669		case AF_INET6:
670			xo->inner_ipproto = ipv6_hdr(skb)->nexthdr;
671			break;
672		default:
673			break;
674		}
675
676		return;
677	}
678
679	/* non-Tunnel Mode */
680	if (!skb->encapsulation)
681		return;
682
683	if (skb->inner_protocol_type == ENCAP_TYPE_IPPROTO) {
684		xo->inner_ipproto = skb->inner_ipproto;
685		return;
686	}
687
688	if (skb->inner_protocol_type != ENCAP_TYPE_ETHER)
689		return;
690
691	eth = (struct ethhdr *)skb_inner_mac_header(skb);
692
693	switch (ntohs(eth->h_proto)) {
694	case ETH_P_IPV6:
695		xo->inner_ipproto = inner_ipv6_hdr(skb)->nexthdr;
696		break;
697	case ETH_P_IP:
698		xo->inner_ipproto = inner_ip_hdr(skb)->protocol;
699		break;
700	}
701}
702
703int xfrm_output(struct sock *sk, struct sk_buff *skb)
704{
705	struct net *net = dev_net(skb_dst(skb)->dev);
706	struct xfrm_state *x = skb_dst(skb)->xfrm;
707	int family;
708	int err;
709
710	family = (x->xso.type != XFRM_DEV_OFFLOAD_PACKET) ? x->outer_mode.family
711		: skb_dst(skb)->ops->family;
712
713	switch (family) {
714	case AF_INET:
715		memset(IPCB(skb), 0, sizeof(*IPCB(skb)));
716		IPCB(skb)->flags |= IPSKB_XFRM_TRANSFORMED;
717		break;
718	case AF_INET6:
719		memset(IP6CB(skb), 0, sizeof(*IP6CB(skb)));
720
721		IP6CB(skb)->flags |= IP6SKB_XFRM_TRANSFORMED;
722		break;
723	}
724
725	if (x->xso.type == XFRM_DEV_OFFLOAD_PACKET) {
726		if (!xfrm_dev_offload_ok(skb, x)) {
727			XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTERROR);
728			kfree_skb(skb);
729			return -EHOSTUNREACH;
730		}
731
732		return xfrm_output_resume(sk, skb, 0);
733	}
734
735	secpath_reset(skb);
736
737	if (xfrm_dev_offload_ok(skb, x)) {
738		struct sec_path *sp;
739
740		sp = secpath_set(skb);
741		if (!sp) {
742			XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTERROR);
743			kfree_skb(skb);
744			return -ENOMEM;
745		}
746
747		sp->olen++;
748		sp->xvec[sp->len++] = x;
749		xfrm_state_hold(x);
750
751		xfrm_get_inner_ipproto(skb, x);
752		skb->encapsulation = 1;
753
754		if (skb_is_gso(skb)) {
755			if (skb->inner_protocol)
756				return xfrm_output_gso(net, sk, skb);
757
758			skb_shinfo(skb)->gso_type |= SKB_GSO_ESP;
759			goto out;
760		}
761
762		if (x->xso.dev && x->xso.dev->features & NETIF_F_HW_ESP_TX_CSUM)
763			goto out;
764	} else {
765		if (skb_is_gso(skb))
766			return xfrm_output_gso(net, sk, skb);
767	}
768
769	if (skb->ip_summed == CHECKSUM_PARTIAL) {
770		err = skb_checksum_help(skb);
771		if (err) {
772			XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTERROR);
773			kfree_skb(skb);
774			return err;
775		}
776	}
777
778out:
779	return xfrm_output2(net, sk, skb);
780}
781EXPORT_SYMBOL_GPL(xfrm_output);
782
783static int xfrm4_tunnel_check_size(struct sk_buff *skb)
784{
785	int mtu, ret = 0;
786
787	if (IPCB(skb)->flags & IPSKB_XFRM_TUNNEL_SIZE)
788		goto out;
789
790	if (!(ip_hdr(skb)->frag_off & htons(IP_DF)) || skb->ignore_df)
791		goto out;
792
793	mtu = dst_mtu(skb_dst(skb));
794	if ((!skb_is_gso(skb) && skb->len > mtu) ||
795	    (skb_is_gso(skb) &&
796	     !skb_gso_validate_network_len(skb, ip_skb_dst_mtu(skb->sk, skb)))) {
797		skb->protocol = htons(ETH_P_IP);
798
799		if (skb->sk)
800			xfrm_local_error(skb, mtu);
801		else
802			icmp_send(skb, ICMP_DEST_UNREACH,
803				  ICMP_FRAG_NEEDED, htonl(mtu));
804		ret = -EMSGSIZE;
805	}
806out:
807	return ret;
808}
809
810static int xfrm4_extract_output(struct xfrm_state *x, struct sk_buff *skb)
811{
812	int err;
813
814	if (x->outer_mode.encap == XFRM_MODE_BEET &&
815	    ip_is_fragment(ip_hdr(skb))) {
816		net_warn_ratelimited("BEET mode doesn't support inner IPv4 fragments\n");
817		return -EAFNOSUPPORT;
818	}
819
820	err = xfrm4_tunnel_check_size(skb);
821	if (err)
822		return err;
823
824	XFRM_MODE_SKB_CB(skb)->protocol = ip_hdr(skb)->protocol;
825
826	xfrm4_extract_header(skb);
827	return 0;
828}
829
830#if IS_ENABLED(CONFIG_IPV6)
831static int xfrm6_tunnel_check_size(struct sk_buff *skb)
832{
833	int mtu, ret = 0;
834	struct dst_entry *dst = skb_dst(skb);
835
836	if (skb->ignore_df)
837		goto out;
838
839	mtu = dst_mtu(dst);
840	if (mtu < IPV6_MIN_MTU)
841		mtu = IPV6_MIN_MTU;
842
843	if ((!skb_is_gso(skb) && skb->len > mtu) ||
844	    (skb_is_gso(skb) &&
845	     !skb_gso_validate_network_len(skb, ip6_skb_dst_mtu(skb)))) {
846		skb->dev = dst->dev;
847		skb->protocol = htons(ETH_P_IPV6);
848
849		if (xfrm6_local_dontfrag(skb->sk))
850			ipv6_stub->xfrm6_local_rxpmtu(skb, mtu);
851		else if (skb->sk)
852			xfrm_local_error(skb, mtu);
853		else
854			icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu);
855		ret = -EMSGSIZE;
856	}
857out:
858	return ret;
859}
860#endif
861
862static int xfrm6_extract_output(struct xfrm_state *x, struct sk_buff *skb)
863{
864#if IS_ENABLED(CONFIG_IPV6)
865	int err;
866
867	err = xfrm6_tunnel_check_size(skb);
868	if (err)
869		return err;
870
871	XFRM_MODE_SKB_CB(skb)->protocol = ipv6_hdr(skb)->nexthdr;
872
873	xfrm6_extract_header(skb);
874	return 0;
875#else
876	WARN_ON_ONCE(1);
877	return -EAFNOSUPPORT;
878#endif
879}
880
881static int xfrm_inner_extract_output(struct xfrm_state *x, struct sk_buff *skb)
882{
883	switch (skb->protocol) {
884	case htons(ETH_P_IP):
885		return xfrm4_extract_output(x, skb);
886	case htons(ETH_P_IPV6):
887		return xfrm6_extract_output(x, skb);
888	}
889
890	return -EAFNOSUPPORT;
891}
892
893void xfrm_local_error(struct sk_buff *skb, int mtu)
894{
895	unsigned int proto;
896	struct xfrm_state_afinfo *afinfo;
897
898	if (skb->protocol == htons(ETH_P_IP))
899		proto = AF_INET;
900	else if (skb->protocol == htons(ETH_P_IPV6) &&
901		 skb->sk->sk_family == AF_INET6)
902		proto = AF_INET6;
903	else
904		return;
905
906	afinfo = xfrm_state_get_afinfo(proto);
907	if (afinfo) {
908		afinfo->local_error(skb, mtu);
909		rcu_read_unlock();
910	}
911}
912EXPORT_SYMBOL_GPL(xfrm_local_error);
913