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Linux/net/xfrm/xfrm_output.c

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  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 /* 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  */
 85 static 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  */
116 static 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  */
148 static 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  */
197 static 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)
242 static 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 
277 static 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  */
328 static 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 
350 static 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 
376 static 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)
406 int pktgen_xfrm_outer_mode_output(struct xfrm_state *x, struct sk_buff *skb)
407 {
408         return xfrm_outer_mode_output(x, skb);
409 }
410 EXPORT_SYMBOL_GPL(pktgen_xfrm_outer_mode_output);
411 #endif
412 
413 static 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 
480 resume:
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 
498 error:
499         spin_unlock_bh(&x->lock);
500 error_nolock:
501         kfree_skb(skb);
502 out:
503         return err;
504 }
505 
506 int 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 
530 out:
531         return err;
532 }
533 EXPORT_SYMBOL_GPL(xfrm_output_resume);
534 
535 static int xfrm_output2(struct net *net, struct sock *sk, struct sk_buff *skb)
536 {
537         return xfrm_output_resume(skb, 1);
538 }
539 
540 static 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 
568 int 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 
627 out:
628         return xfrm_output2(net, sk, skb);
629 }
630 EXPORT_SYMBOL_GPL(xfrm_output);
631 
632 static 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         }
655 out:
656         return ret;
657 }
658 
659 static 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)
674 static 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         }
700 out:
701         return ret;
702 }
703 #endif
704 
705 static 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 
724 static 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 
747 void 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 }
766 EXPORT_SYMBOL_GPL(xfrm_local_error);
767 

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