xref: /openbmc/linux/net/xfrm/xfrm_output.c (revision 0ad53fe3) 
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 
27 static int xfrm_output2(struct net *net, struct sock *sk, struct sk_buff *skb);
28 static int xfrm_inner_extract_output(struct xfrm_state *x, struct sk_buff *skb);
29 
30 static 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 
51 static 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  */
64 static 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)
81 static 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)
141 static 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  */
162 static 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  */
193 static 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 	x->lastused = ktime_get_real_seconds();
213 
214 	return 0;
215 #else
216 	WARN_ON_ONCE(1);
217 	return -EAFNOSUPPORT;
218 #endif
219 }
220 
221 /* Add encapsulation header.
222  *
223  * The top IP header will be constructed per draft-nikander-esp-beet-mode-06.txt.
224  */
225 static int xfrm4_beet_encap_add(struct xfrm_state *x, struct sk_buff *skb)
226 {
227 	struct ip_beet_phdr *ph;
228 	struct iphdr *top_iph;
229 	int hdrlen, optlen;
230 
231 	hdrlen = 0;
232 	optlen = XFRM_MODE_SKB_CB(skb)->optlen;
233 	if (unlikely(optlen))
234 		hdrlen += IPV4_BEET_PHMAXLEN - (optlen & 4);
235 
236 	skb_set_network_header(skb, -x->props.header_len - hdrlen +
237 			       (XFRM_MODE_SKB_CB(skb)->ihl - sizeof(*top_iph)));
238 	if (x->sel.family != AF_INET6)
239 		skb->network_header += IPV4_BEET_PHMAXLEN;
240 	skb->mac_header = skb->network_header +
241 			  offsetof(struct iphdr, protocol);
242 	skb->transport_header = skb->network_header + sizeof(*top_iph);
243 
244 	xfrm4_beet_make_header(skb);
245 
246 	ph = __skb_pull(skb, XFRM_MODE_SKB_CB(skb)->ihl - hdrlen);
247 
248 	top_iph = ip_hdr(skb);
249 
250 	if (unlikely(optlen)) {
251 		if (WARN_ON(optlen < 0))
252 			return -EINVAL;
253 
254 		ph->padlen = 4 - (optlen & 4);
255 		ph->hdrlen = optlen / 8;
256 		ph->nexthdr = top_iph->protocol;
257 		if (ph->padlen)
258 			memset(ph + 1, IPOPT_NOP, ph->padlen);
259 
260 		top_iph->protocol = IPPROTO_BEETPH;
261 		top_iph->ihl = sizeof(struct iphdr) / 4;
262 	}
263 
264 	top_iph->saddr = x->props.saddr.a4;
265 	top_iph->daddr = x->id.daddr.a4;
266 
267 	return 0;
268 }
269 
270 /* Add encapsulation header.
271  *
272  * The top IP header will be constructed per RFC 2401.
273  */
274 static int xfrm4_tunnel_encap_add(struct xfrm_state *x, struct sk_buff *skb)
275 {
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) ?
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)
319 static 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 
354 static 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  */
405 static 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->outer_mode.encap) {
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 
427 static 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->outer_mode.encap) {
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 
453 static int xfrm_outer_mode_output(struct xfrm_state *x, struct sk_buff *skb)
454 {
455 	switch (x->outer_mode.encap) {
456 	case XFRM_MODE_BEET:
457 	case XFRM_MODE_TUNNEL:
458 		if (x->outer_mode.family == AF_INET)
459 			return xfrm4_prepare_output(x, skb);
460 		if (x->outer_mode.family == AF_INET6)
461 			return xfrm6_prepare_output(x, skb);
462 		break;
463 	case XFRM_MODE_TRANSPORT:
464 		if (x->outer_mode.family == AF_INET)
465 			return xfrm4_transport_output(x, skb);
466 		if (x->outer_mode.family == AF_INET6)
467 			return xfrm6_transport_output(x, skb);
468 		break;
469 	case XFRM_MODE_ROUTEOPTIMIZATION:
470 		if (x->outer_mode.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)
483 int pktgen_xfrm_outer_mode_output(struct xfrm_state *x, struct sk_buff *skb)
484 {
485 	return xfrm_outer_mode_output(x, skb);
486 }
487 EXPORT_SYMBOL_GPL(pktgen_xfrm_outer_mode_output);
488 #endif
489 
490 static 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)
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 
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 
557 resume:
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 
575 error:
576 	spin_unlock_bh(&x->lock);
577 error_nolock:
578 	kfree_skb(skb);
579 out:
580 	return err;
581 }
582 
583 int 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 
607 out:
608 	return err;
609 }
610 EXPORT_SYMBOL_GPL(xfrm_output_resume);
611 
612 static int xfrm_output2(struct net *net, struct sock *sk, struct sk_buff *skb)
613 {
614 	return xfrm_output_resume(sk, skb, 1);
615 }
616 
617 static 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  * If the encap type is IPIP, just save skb->inner_ipproto. Otherwise,
651  * get the ip protocol from the IP header.
652  */
653 static void xfrm_get_inner_ipproto(struct sk_buff *skb)
654 {
655 	struct xfrm_offload *xo = xfrm_offload(skb);
656 	const struct ethhdr *eth;
657 
658 	if (!xo)
659 		return;
660 
661 	if (skb->inner_protocol_type == ENCAP_TYPE_IPPROTO) {
662 		xo->inner_ipproto = skb->inner_ipproto;
663 		return;
664 	}
665 
666 	if (skb->inner_protocol_type != ENCAP_TYPE_ETHER)
667 		return;
668 
669 	eth = (struct ethhdr *)skb_inner_mac_header(skb);
670 
671 	switch (ntohs(eth->h_proto)) {
672 	case ETH_P_IPV6:
673 		xo->inner_ipproto = inner_ipv6_hdr(skb)->nexthdr;
674 		break;
675 	case ETH_P_IP:
676 		xo->inner_ipproto = inner_ip_hdr(skb)->protocol;
677 		break;
678 	}
679 }
680 
681 int xfrm_output(struct sock *sk, struct sk_buff *skb)
682 {
683 	struct net *net = dev_net(skb_dst(skb)->dev);
684 	struct xfrm_state *x = skb_dst(skb)->xfrm;
685 	int err;
686 
687 	switch (x->outer_mode.family) {
688 	case AF_INET:
689 		memset(IPCB(skb), 0, sizeof(*IPCB(skb)));
690 		IPCB(skb)->flags |= IPSKB_XFRM_TRANSFORMED;
691 		break;
692 	case AF_INET6:
693 		memset(IP6CB(skb), 0, sizeof(*IP6CB(skb)));
694 
695 		IP6CB(skb)->flags |= IP6SKB_XFRM_TRANSFORMED;
696 		break;
697 	}
698 
699 	secpath_reset(skb);
700 
701 	if (xfrm_dev_offload_ok(skb, x)) {
702 		struct sec_path *sp;
703 
704 		sp = secpath_set(skb);
705 		if (!sp) {
706 			XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTERROR);
707 			kfree_skb(skb);
708 			return -ENOMEM;
709 		}
710 
711 		sp->olen++;
712 		sp->xvec[sp->len++] = x;
713 		xfrm_state_hold(x);
714 
715 		if (skb->encapsulation)
716 			xfrm_get_inner_ipproto(skb);
717 		skb->encapsulation = 1;
718 
719 		if (skb_is_gso(skb)) {
720 			if (skb->inner_protocol)
721 				return xfrm_output_gso(net, sk, skb);
722 
723 			skb_shinfo(skb)->gso_type |= SKB_GSO_ESP;
724 			goto out;
725 		}
726 
727 		if (x->xso.dev && x->xso.dev->features & NETIF_F_HW_ESP_TX_CSUM)
728 			goto out;
729 	} else {
730 		if (skb_is_gso(skb))
731 			return xfrm_output_gso(net, sk, skb);
732 	}
733 
734 	if (skb->ip_summed == CHECKSUM_PARTIAL) {
735 		err = skb_checksum_help(skb);
736 		if (err) {
737 			XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTERROR);
738 			kfree_skb(skb);
739 			return err;
740 		}
741 	}
742 
743 out:
744 	return xfrm_output2(net, sk, skb);
745 }
746 EXPORT_SYMBOL_GPL(xfrm_output);
747 
748 static int xfrm4_tunnel_check_size(struct sk_buff *skb)
749 {
750 	int mtu, ret = 0;
751 
752 	if (IPCB(skb)->flags & IPSKB_XFRM_TUNNEL_SIZE)
753 		goto out;
754 
755 	if (!(ip_hdr(skb)->frag_off & htons(IP_DF)) || skb->ignore_df)
756 		goto out;
757 
758 	mtu = dst_mtu(skb_dst(skb));
759 	if ((!skb_is_gso(skb) && skb->len > mtu) ||
760 	    (skb_is_gso(skb) &&
761 	     !skb_gso_validate_network_len(skb, ip_skb_dst_mtu(skb->sk, skb)))) {
762 		skb->protocol = htons(ETH_P_IP);
763 
764 		if (skb->sk)
765 			xfrm_local_error(skb, mtu);
766 		else
767 			icmp_send(skb, ICMP_DEST_UNREACH,
768 				  ICMP_FRAG_NEEDED, htonl(mtu));
769 		ret = -EMSGSIZE;
770 	}
771 out:
772 	return ret;
773 }
774 
775 static int xfrm4_extract_output(struct xfrm_state *x, struct sk_buff *skb)
776 {
777 	int err;
778 
779 	if (x->outer_mode.encap == XFRM_MODE_BEET &&
780 	    ip_is_fragment(ip_hdr(skb))) {
781 		net_warn_ratelimited("BEET mode doesn't support inner IPv4 fragments\n");
782 		return -EAFNOSUPPORT;
783 	}
784 
785 	err = xfrm4_tunnel_check_size(skb);
786 	if (err)
787 		return err;
788 
789 	XFRM_MODE_SKB_CB(skb)->protocol = ip_hdr(skb)->protocol;
790 
791 	xfrm4_extract_header(skb);
792 	return 0;
793 }
794 
795 #if IS_ENABLED(CONFIG_IPV6)
796 static int xfrm6_tunnel_check_size(struct sk_buff *skb)
797 {
798 	int mtu, ret = 0;
799 	struct dst_entry *dst = skb_dst(skb);
800 
801 	if (skb->ignore_df)
802 		goto out;
803 
804 	mtu = dst_mtu(dst);
805 	if (mtu < IPV6_MIN_MTU)
806 		mtu = IPV6_MIN_MTU;
807 
808 	if ((!skb_is_gso(skb) && skb->len > mtu) ||
809 	    (skb_is_gso(skb) &&
810 	     !skb_gso_validate_network_len(skb, ip6_skb_dst_mtu(skb)))) {
811 		skb->dev = dst->dev;
812 		skb->protocol = htons(ETH_P_IPV6);
813 
814 		if (xfrm6_local_dontfrag(skb->sk))
815 			ipv6_stub->xfrm6_local_rxpmtu(skb, mtu);
816 		else if (skb->sk)
817 			xfrm_local_error(skb, mtu);
818 		else
819 			icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu);
820 		ret = -EMSGSIZE;
821 	}
822 out:
823 	return ret;
824 }
825 #endif
826 
827 static int xfrm6_extract_output(struct xfrm_state *x, struct sk_buff *skb)
828 {
829 #if IS_ENABLED(CONFIG_IPV6)
830 	int err;
831 
832 	err = xfrm6_tunnel_check_size(skb);
833 	if (err)
834 		return err;
835 
836 	XFRM_MODE_SKB_CB(skb)->protocol = ipv6_hdr(skb)->nexthdr;
837 
838 	xfrm6_extract_header(skb);
839 	return 0;
840 #else
841 	WARN_ON_ONCE(1);
842 	return -EAFNOSUPPORT;
843 #endif
844 }
845 
846 static int xfrm_inner_extract_output(struct xfrm_state *x, struct sk_buff *skb)
847 {
848 	const struct xfrm_mode *inner_mode;
849 
850 	if (x->sel.family == AF_UNSPEC)
851 		inner_mode = xfrm_ip2inner_mode(x,
852 				xfrm_af2proto(skb_dst(skb)->ops->family));
853 	else
854 		inner_mode = &x->inner_mode;
855 
856 	if (inner_mode == NULL)
857 		return -EAFNOSUPPORT;
858 
859 	switch (inner_mode->family) {
860 	case AF_INET:
861 		return xfrm4_extract_output(x, skb);
862 	case AF_INET6:
863 		return xfrm6_extract_output(x, skb);
864 	}
865 
866 	return -EAFNOSUPPORT;
867 }
868 
869 void xfrm_local_error(struct sk_buff *skb, int mtu)
870 {
871 	unsigned int proto;
872 	struct xfrm_state_afinfo *afinfo;
873 
874 	if (skb->protocol == htons(ETH_P_IP))
875 		proto = AF_INET;
876 	else if (skb->protocol == htons(ETH_P_IPV6) &&
877 		 skb->sk->sk_family == AF_INET6)
878 		proto = AF_INET6;
879 	else
880 		return;
881 
882 	afinfo = xfrm_state_get_afinfo(proto);
883 	if (afinfo) {
884 		afinfo->local_error(skb, mtu);
885 		rcu_read_unlock();
886 	}
887 }
888 EXPORT_SYMBOL_GPL(xfrm_local_error);
889