Loading...
1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * SR-IPv6 implementation
4 *
5 * Author:
6 * David Lebrun <david.lebrun@uclouvain.be>
7 */
8
9#include <linux/types.h>
10#include <linux/skbuff.h>
11#include <linux/net.h>
12#include <linux/module.h>
13#include <net/ip.h>
14#include <net/ip_tunnels.h>
15#include <net/lwtunnel.h>
16#include <net/netevent.h>
17#include <net/netns/generic.h>
18#include <net/ip6_fib.h>
19#include <net/route.h>
20#include <net/seg6.h>
21#include <linux/seg6.h>
22#include <linux/seg6_iptunnel.h>
23#include <net/addrconf.h>
24#include <net/ip6_route.h>
25#include <net/dst_cache.h>
26#ifdef CONFIG_IPV6_SEG6_HMAC
27#include <net/seg6_hmac.h>
28#endif
29#include <linux/netfilter.h>
30
31static size_t seg6_lwt_headroom(struct seg6_iptunnel_encap *tuninfo)
32{
33 int head = 0;
34
35 switch (tuninfo->mode) {
36 case SEG6_IPTUN_MODE_INLINE:
37 break;
38 case SEG6_IPTUN_MODE_ENCAP:
39 case SEG6_IPTUN_MODE_ENCAP_RED:
40 head = sizeof(struct ipv6hdr);
41 break;
42 case SEG6_IPTUN_MODE_L2ENCAP:
43 case SEG6_IPTUN_MODE_L2ENCAP_RED:
44 return 0;
45 }
46
47 return ((tuninfo->srh->hdrlen + 1) << 3) + head;
48}
49
50struct seg6_lwt {
51 struct dst_cache cache;
52 struct seg6_iptunnel_encap tuninfo[];
53};
54
55static inline struct seg6_lwt *seg6_lwt_lwtunnel(struct lwtunnel_state *lwt)
56{
57 return (struct seg6_lwt *)lwt->data;
58}
59
60static inline struct seg6_iptunnel_encap *
61seg6_encap_lwtunnel(struct lwtunnel_state *lwt)
62{
63 return seg6_lwt_lwtunnel(lwt)->tuninfo;
64}
65
66static const struct nla_policy seg6_iptunnel_policy[SEG6_IPTUNNEL_MAX + 1] = {
67 [SEG6_IPTUNNEL_SRH] = { .type = NLA_BINARY },
68};
69
70static int nla_put_srh(struct sk_buff *skb, int attrtype,
71 struct seg6_iptunnel_encap *tuninfo)
72{
73 struct seg6_iptunnel_encap *data;
74 struct nlattr *nla;
75 int len;
76
77 len = SEG6_IPTUN_ENCAP_SIZE(tuninfo);
78
79 nla = nla_reserve(skb, attrtype, len);
80 if (!nla)
81 return -EMSGSIZE;
82
83 data = nla_data(nla);
84 memcpy(data, tuninfo, len);
85
86 return 0;
87}
88
89static void set_tun_src(struct net *net, struct net_device *dev,
90 struct in6_addr *daddr, struct in6_addr *saddr)
91{
92 struct seg6_pernet_data *sdata = seg6_pernet(net);
93 struct in6_addr *tun_src;
94
95 rcu_read_lock();
96
97 tun_src = rcu_dereference(sdata->tun_src);
98
99 if (!ipv6_addr_any(tun_src)) {
100 memcpy(saddr, tun_src, sizeof(struct in6_addr));
101 } else {
102 ipv6_dev_get_saddr(net, dev, daddr, IPV6_PREFER_SRC_PUBLIC,
103 saddr);
104 }
105
106 rcu_read_unlock();
107}
108
109/* Compute flowlabel for outer IPv6 header */
110static __be32 seg6_make_flowlabel(struct net *net, struct sk_buff *skb,
111 struct ipv6hdr *inner_hdr)
112{
113 int do_flowlabel = net->ipv6.sysctl.seg6_flowlabel;
114 __be32 flowlabel = 0;
115 u32 hash;
116
117 if (do_flowlabel > 0) {
118 hash = skb_get_hash(skb);
119 hash = rol32(hash, 16);
120 flowlabel = (__force __be32)hash & IPV6_FLOWLABEL_MASK;
121 } else if (!do_flowlabel && skb->protocol == htons(ETH_P_IPV6)) {
122 flowlabel = ip6_flowlabel(inner_hdr);
123 }
124 return flowlabel;
125}
126
127static int __seg6_do_srh_encap(struct sk_buff *skb, struct ipv6_sr_hdr *osrh,
128 int proto, struct dst_entry *cache_dst)
129{
130 struct dst_entry *dst = skb_dst(skb);
131 struct net *net = dev_net(dst->dev);
132 struct ipv6hdr *hdr, *inner_hdr;
133 struct ipv6_sr_hdr *isrh;
134 int hdrlen, tot_len, err;
135 __be32 flowlabel;
136
137 hdrlen = (osrh->hdrlen + 1) << 3;
138 tot_len = hdrlen + sizeof(*hdr);
139
140 err = skb_cow_head(skb, tot_len + dst_dev_overhead(cache_dst, skb));
141 if (unlikely(err))
142 return err;
143
144 inner_hdr = ipv6_hdr(skb);
145 flowlabel = seg6_make_flowlabel(net, skb, inner_hdr);
146
147 skb_push(skb, tot_len);
148 skb_reset_network_header(skb);
149 skb_mac_header_rebuild(skb);
150 hdr = ipv6_hdr(skb);
151
152 /* inherit tc, flowlabel and hlim
153 * hlim will be decremented in ip6_forward() afterwards and
154 * decapsulation will overwrite inner hlim with outer hlim
155 */
156
157 if (skb->protocol == htons(ETH_P_IPV6)) {
158 ip6_flow_hdr(hdr, ip6_tclass(ip6_flowinfo(inner_hdr)),
159 flowlabel);
160 hdr->hop_limit = inner_hdr->hop_limit;
161 } else {
162 ip6_flow_hdr(hdr, 0, flowlabel);
163 hdr->hop_limit = ip6_dst_hoplimit(skb_dst(skb));
164
165 memset(IP6CB(skb), 0, sizeof(*IP6CB(skb)));
166
167 /* the control block has been erased, so we have to set the
168 * iif once again.
169 * We read the receiving interface index directly from the
170 * skb->skb_iif as it is done in the IPv4 receiving path (i.e.:
171 * ip_rcv_core(...)).
172 */
173 IP6CB(skb)->iif = skb->skb_iif;
174 }
175
176 hdr->nexthdr = NEXTHDR_ROUTING;
177
178 isrh = (void *)hdr + sizeof(*hdr);
179 memcpy(isrh, osrh, hdrlen);
180
181 isrh->nexthdr = proto;
182
183 hdr->daddr = isrh->segments[isrh->first_segment];
184 set_tun_src(net, dst->dev, &hdr->daddr, &hdr->saddr);
185
186#ifdef CONFIG_IPV6_SEG6_HMAC
187 if (sr_has_hmac(isrh)) {
188 err = seg6_push_hmac(net, &hdr->saddr, isrh);
189 if (unlikely(err))
190 return err;
191 }
192#endif
193
194 hdr->payload_len = htons(skb->len - sizeof(struct ipv6hdr));
195
196 skb_postpush_rcsum(skb, hdr, tot_len);
197
198 return 0;
199}
200
201/* encapsulate an IPv6 packet within an outer IPv6 header with a given SRH */
202int seg6_do_srh_encap(struct sk_buff *skb, struct ipv6_sr_hdr *osrh, int proto)
203{
204 return __seg6_do_srh_encap(skb, osrh, proto, NULL);
205}
206EXPORT_SYMBOL_GPL(seg6_do_srh_encap);
207
208/* encapsulate an IPv6 packet within an outer IPv6 header with reduced SRH */
209static int seg6_do_srh_encap_red(struct sk_buff *skb,
210 struct ipv6_sr_hdr *osrh, int proto,
211 struct dst_entry *cache_dst)
212{
213 __u8 first_seg = osrh->first_segment;
214 struct dst_entry *dst = skb_dst(skb);
215 struct net *net = dev_net(dst->dev);
216 struct ipv6hdr *hdr, *inner_hdr;
217 int hdrlen = ipv6_optlen(osrh);
218 int red_tlv_offset, tlv_offset;
219 struct ipv6_sr_hdr *isrh;
220 bool skip_srh = false;
221 __be32 flowlabel;
222 int tot_len, err;
223 int red_hdrlen;
224 int tlvs_len;
225
226 if (first_seg > 0) {
227 red_hdrlen = hdrlen - sizeof(struct in6_addr);
228 } else {
229 /* NOTE: if tag/flags and/or other TLVs are introduced in the
230 * seg6_iptunnel infrastructure, they should be considered when
231 * deciding to skip the SRH.
232 */
233 skip_srh = !sr_has_hmac(osrh);
234
235 red_hdrlen = skip_srh ? 0 : hdrlen;
236 }
237
238 tot_len = red_hdrlen + sizeof(struct ipv6hdr);
239
240 err = skb_cow_head(skb, tot_len + dst_dev_overhead(cache_dst, skb));
241 if (unlikely(err))
242 return err;
243
244 inner_hdr = ipv6_hdr(skb);
245 flowlabel = seg6_make_flowlabel(net, skb, inner_hdr);
246
247 skb_push(skb, tot_len);
248 skb_reset_network_header(skb);
249 skb_mac_header_rebuild(skb);
250 hdr = ipv6_hdr(skb);
251
252 /* based on seg6_do_srh_encap() */
253 if (skb->protocol == htons(ETH_P_IPV6)) {
254 ip6_flow_hdr(hdr, ip6_tclass(ip6_flowinfo(inner_hdr)),
255 flowlabel);
256 hdr->hop_limit = inner_hdr->hop_limit;
257 } else {
258 ip6_flow_hdr(hdr, 0, flowlabel);
259 hdr->hop_limit = ip6_dst_hoplimit(skb_dst(skb));
260
261 memset(IP6CB(skb), 0, sizeof(*IP6CB(skb)));
262 IP6CB(skb)->iif = skb->skb_iif;
263 }
264
265 /* no matter if we have to skip the SRH or not, the first segment
266 * always comes in the pushed IPv6 header.
267 */
268 hdr->daddr = osrh->segments[first_seg];
269
270 if (skip_srh) {
271 hdr->nexthdr = proto;
272
273 set_tun_src(net, dst->dev, &hdr->daddr, &hdr->saddr);
274 goto out;
275 }
276
277 /* we cannot skip the SRH, slow path */
278
279 hdr->nexthdr = NEXTHDR_ROUTING;
280 isrh = (void *)hdr + sizeof(struct ipv6hdr);
281
282 if (unlikely(!first_seg)) {
283 /* this is a very rare case; we have only one SID but
284 * we cannot skip the SRH since we are carrying some
285 * other info.
286 */
287 memcpy(isrh, osrh, hdrlen);
288 goto srcaddr;
289 }
290
291 tlv_offset = sizeof(*osrh) + (first_seg + 1) * sizeof(struct in6_addr);
292 red_tlv_offset = tlv_offset - sizeof(struct in6_addr);
293
294 memcpy(isrh, osrh, red_tlv_offset);
295
296 tlvs_len = hdrlen - tlv_offset;
297 if (unlikely(tlvs_len > 0)) {
298 const void *s = (const void *)osrh + tlv_offset;
299 void *d = (void *)isrh + red_tlv_offset;
300
301 memcpy(d, s, tlvs_len);
302 }
303
304 --isrh->first_segment;
305 isrh->hdrlen -= 2;
306
307srcaddr:
308 isrh->nexthdr = proto;
309 set_tun_src(net, dst->dev, &hdr->daddr, &hdr->saddr);
310
311#ifdef CONFIG_IPV6_SEG6_HMAC
312 if (unlikely(!skip_srh && sr_has_hmac(isrh))) {
313 err = seg6_push_hmac(net, &hdr->saddr, isrh);
314 if (unlikely(err))
315 return err;
316 }
317#endif
318
319out:
320 hdr->payload_len = htons(skb->len - sizeof(struct ipv6hdr));
321
322 skb_postpush_rcsum(skb, hdr, tot_len);
323
324 return 0;
325}
326
327static int __seg6_do_srh_inline(struct sk_buff *skb, struct ipv6_sr_hdr *osrh,
328 struct dst_entry *cache_dst)
329{
330 struct ipv6hdr *hdr, *oldhdr;
331 struct ipv6_sr_hdr *isrh;
332 int hdrlen, err;
333
334 hdrlen = (osrh->hdrlen + 1) << 3;
335
336 err = skb_cow_head(skb, hdrlen + dst_dev_overhead(cache_dst, skb));
337 if (unlikely(err))
338 return err;
339
340 oldhdr = ipv6_hdr(skb);
341
342 skb_pull(skb, sizeof(struct ipv6hdr));
343 skb_postpull_rcsum(skb, skb_network_header(skb),
344 sizeof(struct ipv6hdr));
345
346 skb_push(skb, sizeof(struct ipv6hdr) + hdrlen);
347 skb_reset_network_header(skb);
348 skb_mac_header_rebuild(skb);
349
350 hdr = ipv6_hdr(skb);
351
352 memmove(hdr, oldhdr, sizeof(*hdr));
353
354 isrh = (void *)hdr + sizeof(*hdr);
355 memcpy(isrh, osrh, hdrlen);
356
357 isrh->nexthdr = hdr->nexthdr;
358 hdr->nexthdr = NEXTHDR_ROUTING;
359
360 isrh->segments[0] = hdr->daddr;
361 hdr->daddr = isrh->segments[isrh->first_segment];
362
363#ifdef CONFIG_IPV6_SEG6_HMAC
364 if (sr_has_hmac(isrh)) {
365 struct net *net = dev_net(skb_dst(skb)->dev);
366
367 err = seg6_push_hmac(net, &hdr->saddr, isrh);
368 if (unlikely(err))
369 return err;
370 }
371#endif
372
373 hdr->payload_len = htons(skb->len - sizeof(struct ipv6hdr));
374
375 skb_postpush_rcsum(skb, hdr, sizeof(struct ipv6hdr) + hdrlen);
376
377 return 0;
378}
379
380static int seg6_do_srh(struct sk_buff *skb, struct dst_entry *cache_dst)
381{
382 struct dst_entry *dst = skb_dst(skb);
383 struct seg6_iptunnel_encap *tinfo;
384 int proto, err = 0;
385
386 tinfo = seg6_encap_lwtunnel(dst->lwtstate);
387
388 switch (tinfo->mode) {
389 case SEG6_IPTUN_MODE_INLINE:
390 if (skb->protocol != htons(ETH_P_IPV6))
391 return -EINVAL;
392
393 err = __seg6_do_srh_inline(skb, tinfo->srh, cache_dst);
394 if (err)
395 return err;
396 break;
397 case SEG6_IPTUN_MODE_ENCAP:
398 case SEG6_IPTUN_MODE_ENCAP_RED:
399 err = iptunnel_handle_offloads(skb, SKB_GSO_IPXIP6);
400 if (err)
401 return err;
402
403 if (skb->protocol == htons(ETH_P_IPV6))
404 proto = IPPROTO_IPV6;
405 else if (skb->protocol == htons(ETH_P_IP))
406 proto = IPPROTO_IPIP;
407 else
408 return -EINVAL;
409
410 if (tinfo->mode == SEG6_IPTUN_MODE_ENCAP)
411 err = __seg6_do_srh_encap(skb, tinfo->srh,
412 proto, cache_dst);
413 else
414 err = seg6_do_srh_encap_red(skb, tinfo->srh,
415 proto, cache_dst);
416
417 if (err)
418 return err;
419
420 skb_set_inner_transport_header(skb, skb_transport_offset(skb));
421 skb_set_inner_protocol(skb, skb->protocol);
422 skb->protocol = htons(ETH_P_IPV6);
423 break;
424 case SEG6_IPTUN_MODE_L2ENCAP:
425 case SEG6_IPTUN_MODE_L2ENCAP_RED:
426 if (!skb_mac_header_was_set(skb))
427 return -EINVAL;
428
429 if (pskb_expand_head(skb, skb->mac_len, 0, GFP_ATOMIC) < 0)
430 return -ENOMEM;
431
432 skb_mac_header_rebuild(skb);
433 skb_push(skb, skb->mac_len);
434
435 if (tinfo->mode == SEG6_IPTUN_MODE_L2ENCAP)
436 err = __seg6_do_srh_encap(skb, tinfo->srh,
437 IPPROTO_ETHERNET,
438 cache_dst);
439 else
440 err = seg6_do_srh_encap_red(skb, tinfo->srh,
441 IPPROTO_ETHERNET,
442 cache_dst);
443
444 if (err)
445 return err;
446
447 skb->protocol = htons(ETH_P_IPV6);
448 break;
449 }
450
451 skb_set_transport_header(skb, sizeof(struct ipv6hdr));
452 nf_reset_ct(skb);
453
454 return 0;
455}
456
457/* insert an SRH within an IPv6 packet, just after the IPv6 header */
458int seg6_do_srh_inline(struct sk_buff *skb, struct ipv6_sr_hdr *osrh)
459{
460 return __seg6_do_srh_inline(skb, osrh, NULL);
461}
462EXPORT_SYMBOL_GPL(seg6_do_srh_inline);
463
464static int seg6_input_finish(struct net *net, struct sock *sk,
465 struct sk_buff *skb)
466{
467 return dst_input(skb);
468}
469
470static int seg6_input_core(struct net *net, struct sock *sk,
471 struct sk_buff *skb)
472{
473 struct dst_entry *orig_dst = skb_dst(skb);
474 struct dst_entry *dst = NULL;
475 struct lwtunnel_state *lwtst;
476 struct seg6_lwt *slwt;
477 int err;
478
479 /* We cannot dereference "orig_dst" once ip6_route_input() or
480 * skb_dst_drop() is called. However, in order to detect a dst loop, we
481 * need the address of its lwtstate. So, save the address of lwtstate
482 * now and use it later as a comparison.
483 */
484 lwtst = orig_dst->lwtstate;
485
486 slwt = seg6_lwt_lwtunnel(lwtst);
487
488 local_bh_disable();
489 dst = dst_cache_get(&slwt->cache);
490 local_bh_enable();
491
492 err = seg6_do_srh(skb, dst);
493 if (unlikely(err)) {
494 dst_release(dst);
495 goto drop;
496 }
497
498 if (!dst) {
499 ip6_route_input(skb);
500 dst = skb_dst(skb);
501
502 /* cache only if we don't create a dst reference loop */
503 if (!dst->error && lwtst != dst->lwtstate) {
504 local_bh_disable();
505 dst_cache_set_ip6(&slwt->cache, dst,
506 &ipv6_hdr(skb)->saddr);
507 local_bh_enable();
508 }
509
510 err = skb_cow_head(skb, LL_RESERVED_SPACE(dst->dev));
511 if (unlikely(err))
512 goto drop;
513 } else {
514 skb_dst_drop(skb);
515 skb_dst_set(skb, dst);
516 }
517
518 if (static_branch_unlikely(&nf_hooks_lwtunnel_enabled))
519 return NF_HOOK(NFPROTO_IPV6, NF_INET_LOCAL_OUT,
520 dev_net(skb->dev), NULL, skb, NULL,
521 skb_dst(skb)->dev, seg6_input_finish);
522
523 return seg6_input_finish(dev_net(skb->dev), NULL, skb);
524drop:
525 kfree_skb(skb);
526 return err;
527}
528
529static int seg6_input_nf(struct sk_buff *skb)
530{
531 struct net_device *dev = skb_dst(skb)->dev;
532 struct net *net = dev_net(skb->dev);
533
534 switch (skb->protocol) {
535 case htons(ETH_P_IP):
536 return NF_HOOK(NFPROTO_IPV4, NF_INET_POST_ROUTING, net, NULL,
537 skb, NULL, dev, seg6_input_core);
538 case htons(ETH_P_IPV6):
539 return NF_HOOK(NFPROTO_IPV6, NF_INET_POST_ROUTING, net, NULL,
540 skb, NULL, dev, seg6_input_core);
541 }
542
543 return -EINVAL;
544}
545
546static int seg6_input(struct sk_buff *skb)
547{
548 if (static_branch_unlikely(&nf_hooks_lwtunnel_enabled))
549 return seg6_input_nf(skb);
550
551 return seg6_input_core(dev_net(skb->dev), NULL, skb);
552}
553
554static int seg6_output_core(struct net *net, struct sock *sk,
555 struct sk_buff *skb)
556{
557 struct dst_entry *orig_dst = skb_dst(skb);
558 struct dst_entry *dst = NULL;
559 struct seg6_lwt *slwt;
560 int err;
561
562 slwt = seg6_lwt_lwtunnel(orig_dst->lwtstate);
563
564 local_bh_disable();
565 dst = dst_cache_get(&slwt->cache);
566 local_bh_enable();
567
568 err = seg6_do_srh(skb, dst);
569 if (unlikely(err))
570 goto drop;
571
572 if (unlikely(!dst)) {
573 struct ipv6hdr *hdr = ipv6_hdr(skb);
574 struct flowi6 fl6;
575
576 memset(&fl6, 0, sizeof(fl6));
577 fl6.daddr = hdr->daddr;
578 fl6.saddr = hdr->saddr;
579 fl6.flowlabel = ip6_flowinfo(hdr);
580 fl6.flowi6_mark = skb->mark;
581 fl6.flowi6_proto = hdr->nexthdr;
582
583 dst = ip6_route_output(net, NULL, &fl6);
584 if (dst->error) {
585 err = dst->error;
586 goto drop;
587 }
588
589 /* cache only if we don't create a dst reference loop */
590 if (orig_dst->lwtstate != dst->lwtstate) {
591 local_bh_disable();
592 dst_cache_set_ip6(&slwt->cache, dst, &fl6.saddr);
593 local_bh_enable();
594 }
595
596 err = skb_cow_head(skb, LL_RESERVED_SPACE(dst->dev));
597 if (unlikely(err))
598 goto drop;
599 }
600
601 skb_dst_drop(skb);
602 skb_dst_set(skb, dst);
603
604 if (static_branch_unlikely(&nf_hooks_lwtunnel_enabled))
605 return NF_HOOK(NFPROTO_IPV6, NF_INET_LOCAL_OUT, net, sk, skb,
606 NULL, skb_dst(skb)->dev, dst_output);
607
608 return dst_output(net, sk, skb);
609drop:
610 dst_release(dst);
611 kfree_skb(skb);
612 return err;
613}
614
615static int seg6_output_nf(struct net *net, struct sock *sk, struct sk_buff *skb)
616{
617 struct net_device *dev = skb_dst(skb)->dev;
618
619 switch (skb->protocol) {
620 case htons(ETH_P_IP):
621 return NF_HOOK(NFPROTO_IPV4, NF_INET_POST_ROUTING, net, sk, skb,
622 NULL, dev, seg6_output_core);
623 case htons(ETH_P_IPV6):
624 return NF_HOOK(NFPROTO_IPV6, NF_INET_POST_ROUTING, net, sk, skb,
625 NULL, dev, seg6_output_core);
626 }
627
628 return -EINVAL;
629}
630
631static int seg6_output(struct net *net, struct sock *sk, struct sk_buff *skb)
632{
633 if (static_branch_unlikely(&nf_hooks_lwtunnel_enabled))
634 return seg6_output_nf(net, sk, skb);
635
636 return seg6_output_core(net, sk, skb);
637}
638
639static int seg6_build_state(struct net *net, struct nlattr *nla,
640 unsigned int family, const void *cfg,
641 struct lwtunnel_state **ts,
642 struct netlink_ext_ack *extack)
643{
644 struct nlattr *tb[SEG6_IPTUNNEL_MAX + 1];
645 struct seg6_iptunnel_encap *tuninfo;
646 struct lwtunnel_state *newts;
647 int tuninfo_len, min_size;
648 struct seg6_lwt *slwt;
649 int err;
650
651 if (family != AF_INET && family != AF_INET6)
652 return -EINVAL;
653
654 err = nla_parse_nested_deprecated(tb, SEG6_IPTUNNEL_MAX, nla,
655 seg6_iptunnel_policy, extack);
656
657 if (err < 0)
658 return err;
659
660 if (!tb[SEG6_IPTUNNEL_SRH])
661 return -EINVAL;
662
663 tuninfo = nla_data(tb[SEG6_IPTUNNEL_SRH]);
664 tuninfo_len = nla_len(tb[SEG6_IPTUNNEL_SRH]);
665
666 /* tuninfo must contain at least the iptunnel encap structure,
667 * the SRH and one segment
668 */
669 min_size = sizeof(*tuninfo) + sizeof(struct ipv6_sr_hdr) +
670 sizeof(struct in6_addr);
671 if (tuninfo_len < min_size)
672 return -EINVAL;
673
674 switch (tuninfo->mode) {
675 case SEG6_IPTUN_MODE_INLINE:
676 if (family != AF_INET6)
677 return -EINVAL;
678
679 break;
680 case SEG6_IPTUN_MODE_ENCAP:
681 break;
682 case SEG6_IPTUN_MODE_L2ENCAP:
683 break;
684 case SEG6_IPTUN_MODE_ENCAP_RED:
685 break;
686 case SEG6_IPTUN_MODE_L2ENCAP_RED:
687 break;
688 default:
689 return -EINVAL;
690 }
691
692 /* verify that SRH is consistent */
693 if (!seg6_validate_srh(tuninfo->srh, tuninfo_len - sizeof(*tuninfo), false))
694 return -EINVAL;
695
696 newts = lwtunnel_state_alloc(tuninfo_len + sizeof(*slwt));
697 if (!newts)
698 return -ENOMEM;
699
700 slwt = seg6_lwt_lwtunnel(newts);
701
702 err = dst_cache_init(&slwt->cache, GFP_ATOMIC);
703 if (err) {
704 kfree(newts);
705 return err;
706 }
707
708 memcpy(&slwt->tuninfo, tuninfo, tuninfo_len);
709
710 newts->type = LWTUNNEL_ENCAP_SEG6;
711 newts->flags |= LWTUNNEL_STATE_INPUT_REDIRECT;
712
713 if (tuninfo->mode != SEG6_IPTUN_MODE_L2ENCAP)
714 newts->flags |= LWTUNNEL_STATE_OUTPUT_REDIRECT;
715
716 newts->headroom = seg6_lwt_headroom(tuninfo);
717
718 *ts = newts;
719
720 return 0;
721}
722
723static void seg6_destroy_state(struct lwtunnel_state *lwt)
724{
725 dst_cache_destroy(&seg6_lwt_lwtunnel(lwt)->cache);
726}
727
728static int seg6_fill_encap_info(struct sk_buff *skb,
729 struct lwtunnel_state *lwtstate)
730{
731 struct seg6_iptunnel_encap *tuninfo = seg6_encap_lwtunnel(lwtstate);
732
733 if (nla_put_srh(skb, SEG6_IPTUNNEL_SRH, tuninfo))
734 return -EMSGSIZE;
735
736 return 0;
737}
738
739static int seg6_encap_nlsize(struct lwtunnel_state *lwtstate)
740{
741 struct seg6_iptunnel_encap *tuninfo = seg6_encap_lwtunnel(lwtstate);
742
743 return nla_total_size(SEG6_IPTUN_ENCAP_SIZE(tuninfo));
744}
745
746static int seg6_encap_cmp(struct lwtunnel_state *a, struct lwtunnel_state *b)
747{
748 struct seg6_iptunnel_encap *a_hdr = seg6_encap_lwtunnel(a);
749 struct seg6_iptunnel_encap *b_hdr = seg6_encap_lwtunnel(b);
750 int len = SEG6_IPTUN_ENCAP_SIZE(a_hdr);
751
752 if (len != SEG6_IPTUN_ENCAP_SIZE(b_hdr))
753 return 1;
754
755 return memcmp(a_hdr, b_hdr, len);
756}
757
758static const struct lwtunnel_encap_ops seg6_iptun_ops = {
759 .build_state = seg6_build_state,
760 .destroy_state = seg6_destroy_state,
761 .output = seg6_output,
762 .input = seg6_input,
763 .fill_encap = seg6_fill_encap_info,
764 .get_encap_size = seg6_encap_nlsize,
765 .cmp_encap = seg6_encap_cmp,
766 .owner = THIS_MODULE,
767};
768
769int __init seg6_iptunnel_init(void)
770{
771 return lwtunnel_encap_add_ops(&seg6_iptun_ops, LWTUNNEL_ENCAP_SEG6);
772}
773
774void seg6_iptunnel_exit(void)
775{
776 lwtunnel_encap_del_ops(&seg6_iptun_ops, LWTUNNEL_ENCAP_SEG6);
777}
1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * SR-IPv6 implementation
4 *
5 * Author:
6 * David Lebrun <david.lebrun@uclouvain.be>
7 */
8
9#include <linux/types.h>
10#include <linux/skbuff.h>
11#include <linux/net.h>
12#include <linux/module.h>
13#include <net/ip.h>
14#include <net/ip_tunnels.h>
15#include <net/lwtunnel.h>
16#include <net/netevent.h>
17#include <net/netns/generic.h>
18#include <net/ip6_fib.h>
19#include <net/route.h>
20#include <net/seg6.h>
21#include <linux/seg6.h>
22#include <linux/seg6_iptunnel.h>
23#include <net/addrconf.h>
24#include <net/ip6_route.h>
25#include <net/dst_cache.h>
26#ifdef CONFIG_IPV6_SEG6_HMAC
27#include <net/seg6_hmac.h>
28#endif
29
30struct seg6_lwt {
31 struct dst_cache cache;
32 struct seg6_iptunnel_encap tuninfo[0];
33};
34
35static inline struct seg6_lwt *seg6_lwt_lwtunnel(struct lwtunnel_state *lwt)
36{
37 return (struct seg6_lwt *)lwt->data;
38}
39
40static inline struct seg6_iptunnel_encap *
41seg6_encap_lwtunnel(struct lwtunnel_state *lwt)
42{
43 return seg6_lwt_lwtunnel(lwt)->tuninfo;
44}
45
46static const struct nla_policy seg6_iptunnel_policy[SEG6_IPTUNNEL_MAX + 1] = {
47 [SEG6_IPTUNNEL_SRH] = { .type = NLA_BINARY },
48};
49
50static int nla_put_srh(struct sk_buff *skb, int attrtype,
51 struct seg6_iptunnel_encap *tuninfo)
52{
53 struct seg6_iptunnel_encap *data;
54 struct nlattr *nla;
55 int len;
56
57 len = SEG6_IPTUN_ENCAP_SIZE(tuninfo);
58
59 nla = nla_reserve(skb, attrtype, len);
60 if (!nla)
61 return -EMSGSIZE;
62
63 data = nla_data(nla);
64 memcpy(data, tuninfo, len);
65
66 return 0;
67}
68
69static void set_tun_src(struct net *net, struct net_device *dev,
70 struct in6_addr *daddr, struct in6_addr *saddr)
71{
72 struct seg6_pernet_data *sdata = seg6_pernet(net);
73 struct in6_addr *tun_src;
74
75 rcu_read_lock();
76
77 tun_src = rcu_dereference(sdata->tun_src);
78
79 if (!ipv6_addr_any(tun_src)) {
80 memcpy(saddr, tun_src, sizeof(struct in6_addr));
81 } else {
82 ipv6_dev_get_saddr(net, dev, daddr, IPV6_PREFER_SRC_PUBLIC,
83 saddr);
84 }
85
86 rcu_read_unlock();
87}
88
89/* Compute flowlabel for outer IPv6 header */
90static __be32 seg6_make_flowlabel(struct net *net, struct sk_buff *skb,
91 struct ipv6hdr *inner_hdr)
92{
93 int do_flowlabel = net->ipv6.sysctl.seg6_flowlabel;
94 __be32 flowlabel = 0;
95 u32 hash;
96
97 if (do_flowlabel > 0) {
98 hash = skb_get_hash(skb);
99 hash = rol32(hash, 16);
100 flowlabel = (__force __be32)hash & IPV6_FLOWLABEL_MASK;
101 } else if (!do_flowlabel && skb->protocol == htons(ETH_P_IPV6)) {
102 flowlabel = ip6_flowlabel(inner_hdr);
103 }
104 return flowlabel;
105}
106
107/* encapsulate an IPv6 packet within an outer IPv6 header with a given SRH */
108int seg6_do_srh_encap(struct sk_buff *skb, struct ipv6_sr_hdr *osrh, int proto)
109{
110 struct dst_entry *dst = skb_dst(skb);
111 struct net *net = dev_net(dst->dev);
112 struct ipv6hdr *hdr, *inner_hdr;
113 struct ipv6_sr_hdr *isrh;
114 int hdrlen, tot_len, err;
115 __be32 flowlabel;
116
117 hdrlen = (osrh->hdrlen + 1) << 3;
118 tot_len = hdrlen + sizeof(*hdr);
119
120 err = skb_cow_head(skb, tot_len + skb->mac_len);
121 if (unlikely(err))
122 return err;
123
124 inner_hdr = ipv6_hdr(skb);
125 flowlabel = seg6_make_flowlabel(net, skb, inner_hdr);
126
127 skb_push(skb, tot_len);
128 skb_reset_network_header(skb);
129 skb_mac_header_rebuild(skb);
130 hdr = ipv6_hdr(skb);
131
132 /* inherit tc, flowlabel and hlim
133 * hlim will be decremented in ip6_forward() afterwards and
134 * decapsulation will overwrite inner hlim with outer hlim
135 */
136
137 if (skb->protocol == htons(ETH_P_IPV6)) {
138 ip6_flow_hdr(hdr, ip6_tclass(ip6_flowinfo(inner_hdr)),
139 flowlabel);
140 hdr->hop_limit = inner_hdr->hop_limit;
141 } else {
142 ip6_flow_hdr(hdr, 0, flowlabel);
143 hdr->hop_limit = ip6_dst_hoplimit(skb_dst(skb));
144
145 memset(IP6CB(skb), 0, sizeof(*IP6CB(skb)));
146 }
147
148 hdr->nexthdr = NEXTHDR_ROUTING;
149
150 isrh = (void *)hdr + sizeof(*hdr);
151 memcpy(isrh, osrh, hdrlen);
152
153 isrh->nexthdr = proto;
154
155 hdr->daddr = isrh->segments[isrh->first_segment];
156 set_tun_src(net, dst->dev, &hdr->daddr, &hdr->saddr);
157
158#ifdef CONFIG_IPV6_SEG6_HMAC
159 if (sr_has_hmac(isrh)) {
160 err = seg6_push_hmac(net, &hdr->saddr, isrh);
161 if (unlikely(err))
162 return err;
163 }
164#endif
165
166 skb_postpush_rcsum(skb, hdr, tot_len);
167
168 return 0;
169}
170EXPORT_SYMBOL_GPL(seg6_do_srh_encap);
171
172/* insert an SRH within an IPv6 packet, just after the IPv6 header */
173int seg6_do_srh_inline(struct sk_buff *skb, struct ipv6_sr_hdr *osrh)
174{
175 struct ipv6hdr *hdr, *oldhdr;
176 struct ipv6_sr_hdr *isrh;
177 int hdrlen, err;
178
179 hdrlen = (osrh->hdrlen + 1) << 3;
180
181 err = skb_cow_head(skb, hdrlen + skb->mac_len);
182 if (unlikely(err))
183 return err;
184
185 oldhdr = ipv6_hdr(skb);
186
187 skb_pull(skb, sizeof(struct ipv6hdr));
188 skb_postpull_rcsum(skb, skb_network_header(skb),
189 sizeof(struct ipv6hdr));
190
191 skb_push(skb, sizeof(struct ipv6hdr) + hdrlen);
192 skb_reset_network_header(skb);
193 skb_mac_header_rebuild(skb);
194
195 hdr = ipv6_hdr(skb);
196
197 memmove(hdr, oldhdr, sizeof(*hdr));
198
199 isrh = (void *)hdr + sizeof(*hdr);
200 memcpy(isrh, osrh, hdrlen);
201
202 isrh->nexthdr = hdr->nexthdr;
203 hdr->nexthdr = NEXTHDR_ROUTING;
204
205 isrh->segments[0] = hdr->daddr;
206 hdr->daddr = isrh->segments[isrh->first_segment];
207
208#ifdef CONFIG_IPV6_SEG6_HMAC
209 if (sr_has_hmac(isrh)) {
210 struct net *net = dev_net(skb_dst(skb)->dev);
211
212 err = seg6_push_hmac(net, &hdr->saddr, isrh);
213 if (unlikely(err))
214 return err;
215 }
216#endif
217
218 skb_postpush_rcsum(skb, hdr, sizeof(struct ipv6hdr) + hdrlen);
219
220 return 0;
221}
222EXPORT_SYMBOL_GPL(seg6_do_srh_inline);
223
224static int seg6_do_srh(struct sk_buff *skb)
225{
226 struct dst_entry *dst = skb_dst(skb);
227 struct seg6_iptunnel_encap *tinfo;
228 int proto, err = 0;
229
230 tinfo = seg6_encap_lwtunnel(dst->lwtstate);
231
232 switch (tinfo->mode) {
233 case SEG6_IPTUN_MODE_INLINE:
234 if (skb->protocol != htons(ETH_P_IPV6))
235 return -EINVAL;
236
237 err = seg6_do_srh_inline(skb, tinfo->srh);
238 if (err)
239 return err;
240 break;
241 case SEG6_IPTUN_MODE_ENCAP:
242 err = iptunnel_handle_offloads(skb, SKB_GSO_IPXIP6);
243 if (err)
244 return err;
245
246 if (skb->protocol == htons(ETH_P_IPV6))
247 proto = IPPROTO_IPV6;
248 else if (skb->protocol == htons(ETH_P_IP))
249 proto = IPPROTO_IPIP;
250 else
251 return -EINVAL;
252
253 err = seg6_do_srh_encap(skb, tinfo->srh, proto);
254 if (err)
255 return err;
256
257 skb_set_inner_transport_header(skb, skb_transport_offset(skb));
258 skb_set_inner_protocol(skb, skb->protocol);
259 skb->protocol = htons(ETH_P_IPV6);
260 break;
261 case SEG6_IPTUN_MODE_L2ENCAP:
262 if (!skb_mac_header_was_set(skb))
263 return -EINVAL;
264
265 if (pskb_expand_head(skb, skb->mac_len, 0, GFP_ATOMIC) < 0)
266 return -ENOMEM;
267
268 skb_mac_header_rebuild(skb);
269 skb_push(skb, skb->mac_len);
270
271 err = seg6_do_srh_encap(skb, tinfo->srh, NEXTHDR_NONE);
272 if (err)
273 return err;
274
275 skb->protocol = htons(ETH_P_IPV6);
276 break;
277 }
278
279 ipv6_hdr(skb)->payload_len = htons(skb->len - sizeof(struct ipv6hdr));
280 skb_set_transport_header(skb, sizeof(struct ipv6hdr));
281
282 return 0;
283}
284
285static int seg6_input(struct sk_buff *skb)
286{
287 struct dst_entry *orig_dst = skb_dst(skb);
288 struct dst_entry *dst = NULL;
289 struct seg6_lwt *slwt;
290 int err;
291
292 err = seg6_do_srh(skb);
293 if (unlikely(err)) {
294 kfree_skb(skb);
295 return err;
296 }
297
298 slwt = seg6_lwt_lwtunnel(orig_dst->lwtstate);
299
300 preempt_disable();
301 dst = dst_cache_get(&slwt->cache);
302 preempt_enable();
303
304 skb_dst_drop(skb);
305
306 if (!dst) {
307 ip6_route_input(skb);
308 dst = skb_dst(skb);
309 if (!dst->error) {
310 preempt_disable();
311 dst_cache_set_ip6(&slwt->cache, dst,
312 &ipv6_hdr(skb)->saddr);
313 preempt_enable();
314 }
315 } else {
316 skb_dst_set(skb, dst);
317 }
318
319 err = skb_cow_head(skb, LL_RESERVED_SPACE(dst->dev));
320 if (unlikely(err))
321 return err;
322
323 return dst_input(skb);
324}
325
326static int seg6_output(struct net *net, struct sock *sk, struct sk_buff *skb)
327{
328 struct dst_entry *orig_dst = skb_dst(skb);
329 struct dst_entry *dst = NULL;
330 struct seg6_lwt *slwt;
331 int err = -EINVAL;
332
333 err = seg6_do_srh(skb);
334 if (unlikely(err))
335 goto drop;
336
337 slwt = seg6_lwt_lwtunnel(orig_dst->lwtstate);
338
339 preempt_disable();
340 dst = dst_cache_get(&slwt->cache);
341 preempt_enable();
342
343 if (unlikely(!dst)) {
344 struct ipv6hdr *hdr = ipv6_hdr(skb);
345 struct flowi6 fl6;
346
347 memset(&fl6, 0, sizeof(fl6));
348 fl6.daddr = hdr->daddr;
349 fl6.saddr = hdr->saddr;
350 fl6.flowlabel = ip6_flowinfo(hdr);
351 fl6.flowi6_mark = skb->mark;
352 fl6.flowi6_proto = hdr->nexthdr;
353
354 dst = ip6_route_output(net, NULL, &fl6);
355 if (dst->error) {
356 err = dst->error;
357 dst_release(dst);
358 goto drop;
359 }
360
361 preempt_disable();
362 dst_cache_set_ip6(&slwt->cache, dst, &fl6.saddr);
363 preempt_enable();
364 }
365
366 skb_dst_drop(skb);
367 skb_dst_set(skb, dst);
368
369 err = skb_cow_head(skb, LL_RESERVED_SPACE(dst->dev));
370 if (unlikely(err))
371 goto drop;
372
373 return dst_output(net, sk, skb);
374drop:
375 kfree_skb(skb);
376 return err;
377}
378
379static int seg6_build_state(struct nlattr *nla,
380 unsigned int family, const void *cfg,
381 struct lwtunnel_state **ts,
382 struct netlink_ext_ack *extack)
383{
384 struct nlattr *tb[SEG6_IPTUNNEL_MAX + 1];
385 struct seg6_iptunnel_encap *tuninfo;
386 struct lwtunnel_state *newts;
387 int tuninfo_len, min_size;
388 struct seg6_lwt *slwt;
389 int err;
390
391 if (family != AF_INET && family != AF_INET6)
392 return -EINVAL;
393
394 err = nla_parse_nested_deprecated(tb, SEG6_IPTUNNEL_MAX, nla,
395 seg6_iptunnel_policy, extack);
396
397 if (err < 0)
398 return err;
399
400 if (!tb[SEG6_IPTUNNEL_SRH])
401 return -EINVAL;
402
403 tuninfo = nla_data(tb[SEG6_IPTUNNEL_SRH]);
404 tuninfo_len = nla_len(tb[SEG6_IPTUNNEL_SRH]);
405
406 /* tuninfo must contain at least the iptunnel encap structure,
407 * the SRH and one segment
408 */
409 min_size = sizeof(*tuninfo) + sizeof(struct ipv6_sr_hdr) +
410 sizeof(struct in6_addr);
411 if (tuninfo_len < min_size)
412 return -EINVAL;
413
414 switch (tuninfo->mode) {
415 case SEG6_IPTUN_MODE_INLINE:
416 if (family != AF_INET6)
417 return -EINVAL;
418
419 break;
420 case SEG6_IPTUN_MODE_ENCAP:
421 break;
422 case SEG6_IPTUN_MODE_L2ENCAP:
423 break;
424 default:
425 return -EINVAL;
426 }
427
428 /* verify that SRH is consistent */
429 if (!seg6_validate_srh(tuninfo->srh, tuninfo_len - sizeof(*tuninfo)))
430 return -EINVAL;
431
432 newts = lwtunnel_state_alloc(tuninfo_len + sizeof(*slwt));
433 if (!newts)
434 return -ENOMEM;
435
436 slwt = seg6_lwt_lwtunnel(newts);
437
438 err = dst_cache_init(&slwt->cache, GFP_ATOMIC);
439 if (err) {
440 kfree(newts);
441 return err;
442 }
443
444 memcpy(&slwt->tuninfo, tuninfo, tuninfo_len);
445
446 newts->type = LWTUNNEL_ENCAP_SEG6;
447 newts->flags |= LWTUNNEL_STATE_INPUT_REDIRECT;
448
449 if (tuninfo->mode != SEG6_IPTUN_MODE_L2ENCAP)
450 newts->flags |= LWTUNNEL_STATE_OUTPUT_REDIRECT;
451
452 newts->headroom = seg6_lwt_headroom(tuninfo);
453
454 *ts = newts;
455
456 return 0;
457}
458
459static void seg6_destroy_state(struct lwtunnel_state *lwt)
460{
461 dst_cache_destroy(&seg6_lwt_lwtunnel(lwt)->cache);
462}
463
464static int seg6_fill_encap_info(struct sk_buff *skb,
465 struct lwtunnel_state *lwtstate)
466{
467 struct seg6_iptunnel_encap *tuninfo = seg6_encap_lwtunnel(lwtstate);
468
469 if (nla_put_srh(skb, SEG6_IPTUNNEL_SRH, tuninfo))
470 return -EMSGSIZE;
471
472 return 0;
473}
474
475static int seg6_encap_nlsize(struct lwtunnel_state *lwtstate)
476{
477 struct seg6_iptunnel_encap *tuninfo = seg6_encap_lwtunnel(lwtstate);
478
479 return nla_total_size(SEG6_IPTUN_ENCAP_SIZE(tuninfo));
480}
481
482static int seg6_encap_cmp(struct lwtunnel_state *a, struct lwtunnel_state *b)
483{
484 struct seg6_iptunnel_encap *a_hdr = seg6_encap_lwtunnel(a);
485 struct seg6_iptunnel_encap *b_hdr = seg6_encap_lwtunnel(b);
486 int len = SEG6_IPTUN_ENCAP_SIZE(a_hdr);
487
488 if (len != SEG6_IPTUN_ENCAP_SIZE(b_hdr))
489 return 1;
490
491 return memcmp(a_hdr, b_hdr, len);
492}
493
494static const struct lwtunnel_encap_ops seg6_iptun_ops = {
495 .build_state = seg6_build_state,
496 .destroy_state = seg6_destroy_state,
497 .output = seg6_output,
498 .input = seg6_input,
499 .fill_encap = seg6_fill_encap_info,
500 .get_encap_size = seg6_encap_nlsize,
501 .cmp_encap = seg6_encap_cmp,
502 .owner = THIS_MODULE,
503};
504
505int __init seg6_iptunnel_init(void)
506{
507 return lwtunnel_encap_add_ops(&seg6_iptun_ops, LWTUNNEL_ENCAP_SEG6);
508}
509
510void seg6_iptunnel_exit(void)
511{
512 lwtunnel_encap_del_ops(&seg6_iptun_ops, LWTUNNEL_ENCAP_SEG6);
513}