seg6_iptunnel.c 11 KB

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  1. /*
  2. * SR-IPv6 implementation
  3. *
  4. * Author:
  5. * David Lebrun <david.lebrun@uclouvain.be>
  6. *
  7. *
  8. * This program is free software; you can redistribute it and/or
  9. * modify it under the terms of the GNU General Public License
  10. * as published by the Free Software Foundation; either version
  11. * 2 of the License, or (at your option) any later version.
  12. */
  13. #include <linux/types.h>
  14. #include <linux/skbuff.h>
  15. #include <linux/net.h>
  16. #include <linux/module.h>
  17. #include <net/ip.h>
  18. #include <net/lwtunnel.h>
  19. #include <net/netevent.h>
  20. #include <net/netns/generic.h>
  21. #include <net/ip6_fib.h>
  22. #include <net/route.h>
  23. #include <net/seg6.h>
  24. #include <linux/seg6.h>
  25. #include <linux/seg6_iptunnel.h>
  26. #include <net/addrconf.h>
  27. #include <net/ip6_route.h>
  28. #include <net/dst_cache.h>
  29. #ifdef CONFIG_IPV6_SEG6_HMAC
  30. #include <net/seg6_hmac.h>
  31. #endif
  32. struct seg6_lwt {
  33. struct dst_cache cache;
  34. struct seg6_iptunnel_encap tuninfo[0];
  35. };
  36. static inline struct seg6_lwt *seg6_lwt_lwtunnel(struct lwtunnel_state *lwt)
  37. {
  38. return (struct seg6_lwt *)lwt->data;
  39. }
  40. static inline struct seg6_iptunnel_encap *
  41. seg6_encap_lwtunnel(struct lwtunnel_state *lwt)
  42. {
  43. return seg6_lwt_lwtunnel(lwt)->tuninfo;
  44. }
  45. static const struct nla_policy seg6_iptunnel_policy[SEG6_IPTUNNEL_MAX + 1] = {
  46. [SEG6_IPTUNNEL_SRH] = { .type = NLA_BINARY },
  47. };
  48. static int nla_put_srh(struct sk_buff *skb, int attrtype,
  49. struct seg6_iptunnel_encap *tuninfo)
  50. {
  51. struct seg6_iptunnel_encap *data;
  52. struct nlattr *nla;
  53. int len;
  54. len = SEG6_IPTUN_ENCAP_SIZE(tuninfo);
  55. nla = nla_reserve(skb, attrtype, len);
  56. if (!nla)
  57. return -EMSGSIZE;
  58. data = nla_data(nla);
  59. memcpy(data, tuninfo, len);
  60. return 0;
  61. }
  62. static void set_tun_src(struct net *net, struct net_device *dev,
  63. struct in6_addr *daddr, struct in6_addr *saddr)
  64. {
  65. struct seg6_pernet_data *sdata = seg6_pernet(net);
  66. struct in6_addr *tun_src;
  67. rcu_read_lock();
  68. tun_src = rcu_dereference(sdata->tun_src);
  69. if (!ipv6_addr_any(tun_src)) {
  70. memcpy(saddr, tun_src, sizeof(struct in6_addr));
  71. } else {
  72. ipv6_dev_get_saddr(net, dev, daddr, IPV6_PREFER_SRC_PUBLIC,
  73. saddr);
  74. }
  75. rcu_read_unlock();
  76. }
  77. /* encapsulate an IPv6 packet within an outer IPv6 header with a given SRH */
  78. int seg6_do_srh_encap(struct sk_buff *skb, struct ipv6_sr_hdr *osrh, int proto)
  79. {
  80. struct net *net = dev_net(skb_dst(skb)->dev);
  81. struct ipv6hdr *hdr, *inner_hdr;
  82. struct ipv6_sr_hdr *isrh;
  83. int hdrlen, tot_len, err;
  84. hdrlen = (osrh->hdrlen + 1) << 3;
  85. tot_len = hdrlen + sizeof(*hdr);
  86. err = skb_cow_head(skb, tot_len);
  87. if (unlikely(err))
  88. return err;
  89. inner_hdr = ipv6_hdr(skb);
  90. skb_push(skb, tot_len);
  91. skb_reset_network_header(skb);
  92. skb_mac_header_rebuild(skb);
  93. hdr = ipv6_hdr(skb);
  94. /* inherit tc, flowlabel and hlim
  95. * hlim will be decremented in ip6_forward() afterwards and
  96. * decapsulation will overwrite inner hlim with outer hlim
  97. */
  98. if (skb->protocol == htons(ETH_P_IPV6)) {
  99. ip6_flow_hdr(hdr, ip6_tclass(ip6_flowinfo(inner_hdr)),
  100. ip6_flowlabel(inner_hdr));
  101. hdr->hop_limit = inner_hdr->hop_limit;
  102. } else {
  103. ip6_flow_hdr(hdr, 0, 0);
  104. hdr->hop_limit = ip6_dst_hoplimit(skb_dst(skb));
  105. }
  106. hdr->nexthdr = NEXTHDR_ROUTING;
  107. isrh = (void *)hdr + sizeof(*hdr);
  108. memcpy(isrh, osrh, hdrlen);
  109. isrh->nexthdr = proto;
  110. hdr->daddr = isrh->segments[isrh->first_segment];
  111. set_tun_src(net, skb->dev, &hdr->daddr, &hdr->saddr);
  112. #ifdef CONFIG_IPV6_SEG6_HMAC
  113. if (sr_has_hmac(isrh)) {
  114. err = seg6_push_hmac(net, &hdr->saddr, isrh);
  115. if (unlikely(err))
  116. return err;
  117. }
  118. #endif
  119. skb_postpush_rcsum(skb, hdr, tot_len);
  120. return 0;
  121. }
  122. EXPORT_SYMBOL_GPL(seg6_do_srh_encap);
  123. /* insert an SRH within an IPv6 packet, just after the IPv6 header */
  124. int seg6_do_srh_inline(struct sk_buff *skb, struct ipv6_sr_hdr *osrh)
  125. {
  126. struct ipv6hdr *hdr, *oldhdr;
  127. struct ipv6_sr_hdr *isrh;
  128. int hdrlen, err;
  129. hdrlen = (osrh->hdrlen + 1) << 3;
  130. err = skb_cow_head(skb, hdrlen);
  131. if (unlikely(err))
  132. return err;
  133. oldhdr = ipv6_hdr(skb);
  134. skb_pull(skb, sizeof(struct ipv6hdr));
  135. skb_postpull_rcsum(skb, skb_network_header(skb),
  136. sizeof(struct ipv6hdr));
  137. skb_push(skb, sizeof(struct ipv6hdr) + hdrlen);
  138. skb_reset_network_header(skb);
  139. skb_mac_header_rebuild(skb);
  140. hdr = ipv6_hdr(skb);
  141. memmove(hdr, oldhdr, sizeof(*hdr));
  142. isrh = (void *)hdr + sizeof(*hdr);
  143. memcpy(isrh, osrh, hdrlen);
  144. isrh->nexthdr = hdr->nexthdr;
  145. hdr->nexthdr = NEXTHDR_ROUTING;
  146. isrh->segments[0] = hdr->daddr;
  147. hdr->daddr = isrh->segments[isrh->first_segment];
  148. #ifdef CONFIG_IPV6_SEG6_HMAC
  149. if (sr_has_hmac(isrh)) {
  150. struct net *net = dev_net(skb_dst(skb)->dev);
  151. err = seg6_push_hmac(net, &hdr->saddr, isrh);
  152. if (unlikely(err))
  153. return err;
  154. }
  155. #endif
  156. skb_postpush_rcsum(skb, hdr, sizeof(struct ipv6hdr) + hdrlen);
  157. return 0;
  158. }
  159. EXPORT_SYMBOL_GPL(seg6_do_srh_inline);
  160. static int seg6_do_srh(struct sk_buff *skb)
  161. {
  162. struct dst_entry *dst = skb_dst(skb);
  163. struct seg6_iptunnel_encap *tinfo;
  164. int proto, err = 0;
  165. tinfo = seg6_encap_lwtunnel(dst->lwtstate);
  166. if (likely(!skb->encapsulation)) {
  167. skb_reset_inner_headers(skb);
  168. skb->encapsulation = 1;
  169. }
  170. switch (tinfo->mode) {
  171. case SEG6_IPTUN_MODE_INLINE:
  172. if (skb->protocol != htons(ETH_P_IPV6))
  173. return -EINVAL;
  174. err = seg6_do_srh_inline(skb, tinfo->srh);
  175. if (err)
  176. return err;
  177. skb_reset_inner_headers(skb);
  178. break;
  179. case SEG6_IPTUN_MODE_ENCAP:
  180. if (skb->protocol == htons(ETH_P_IPV6))
  181. proto = IPPROTO_IPV6;
  182. else if (skb->protocol == htons(ETH_P_IP))
  183. proto = IPPROTO_IPIP;
  184. else
  185. return -EINVAL;
  186. err = seg6_do_srh_encap(skb, tinfo->srh, proto);
  187. if (err)
  188. return err;
  189. skb->protocol = htons(ETH_P_IPV6);
  190. break;
  191. case SEG6_IPTUN_MODE_L2ENCAP:
  192. if (!skb_mac_header_was_set(skb))
  193. return -EINVAL;
  194. if (pskb_expand_head(skb, skb->mac_len, 0, GFP_ATOMIC) < 0)
  195. return -ENOMEM;
  196. skb_mac_header_rebuild(skb);
  197. skb_push(skb, skb->mac_len);
  198. err = seg6_do_srh_encap(skb, tinfo->srh, NEXTHDR_NONE);
  199. if (err)
  200. return err;
  201. skb->protocol = htons(ETH_P_IPV6);
  202. break;
  203. }
  204. ipv6_hdr(skb)->payload_len = htons(skb->len - sizeof(struct ipv6hdr));
  205. skb_set_transport_header(skb, sizeof(struct ipv6hdr));
  206. skb_set_inner_protocol(skb, skb->protocol);
  207. return 0;
  208. }
  209. static int seg6_input(struct sk_buff *skb)
  210. {
  211. struct dst_entry *orig_dst = skb_dst(skb);
  212. struct dst_entry *dst = NULL;
  213. struct seg6_lwt *slwt;
  214. int err;
  215. err = seg6_do_srh(skb);
  216. if (unlikely(err)) {
  217. kfree_skb(skb);
  218. return err;
  219. }
  220. slwt = seg6_lwt_lwtunnel(orig_dst->lwtstate);
  221. preempt_disable();
  222. dst = dst_cache_get(&slwt->cache);
  223. preempt_enable();
  224. skb_dst_drop(skb);
  225. if (!dst) {
  226. ip6_route_input(skb);
  227. dst = skb_dst(skb);
  228. if (!dst->error) {
  229. preempt_disable();
  230. dst_cache_set_ip6(&slwt->cache, dst,
  231. &ipv6_hdr(skb)->saddr);
  232. preempt_enable();
  233. }
  234. } else {
  235. skb_dst_set(skb, dst);
  236. }
  237. err = skb_cow_head(skb, LL_RESERVED_SPACE(dst->dev));
  238. if (unlikely(err))
  239. return err;
  240. return dst_input(skb);
  241. }
  242. static int seg6_output(struct net *net, struct sock *sk, struct sk_buff *skb)
  243. {
  244. struct dst_entry *orig_dst = skb_dst(skb);
  245. struct dst_entry *dst = NULL;
  246. struct seg6_lwt *slwt;
  247. int err = -EINVAL;
  248. err = seg6_do_srh(skb);
  249. if (unlikely(err))
  250. goto drop;
  251. slwt = seg6_lwt_lwtunnel(orig_dst->lwtstate);
  252. preempt_disable();
  253. dst = dst_cache_get(&slwt->cache);
  254. preempt_enable();
  255. if (unlikely(!dst)) {
  256. struct ipv6hdr *hdr = ipv6_hdr(skb);
  257. struct flowi6 fl6;
  258. fl6.daddr = hdr->daddr;
  259. fl6.saddr = hdr->saddr;
  260. fl6.flowlabel = ip6_flowinfo(hdr);
  261. fl6.flowi6_mark = skb->mark;
  262. fl6.flowi6_proto = hdr->nexthdr;
  263. dst = ip6_route_output(net, NULL, &fl6);
  264. if (dst->error) {
  265. err = dst->error;
  266. dst_release(dst);
  267. goto drop;
  268. }
  269. preempt_disable();
  270. dst_cache_set_ip6(&slwt->cache, dst, &fl6.saddr);
  271. preempt_enable();
  272. }
  273. skb_dst_drop(skb);
  274. skb_dst_set(skb, dst);
  275. err = skb_cow_head(skb, LL_RESERVED_SPACE(dst->dev));
  276. if (unlikely(err))
  277. goto drop;
  278. return dst_output(net, sk, skb);
  279. drop:
  280. kfree_skb(skb);
  281. return err;
  282. }
  283. static int seg6_build_state(struct nlattr *nla,
  284. unsigned int family, const void *cfg,
  285. struct lwtunnel_state **ts,
  286. struct netlink_ext_ack *extack)
  287. {
  288. struct nlattr *tb[SEG6_IPTUNNEL_MAX + 1];
  289. struct seg6_iptunnel_encap *tuninfo;
  290. struct lwtunnel_state *newts;
  291. int tuninfo_len, min_size;
  292. struct seg6_lwt *slwt;
  293. int err;
  294. if (family != AF_INET && family != AF_INET6)
  295. return -EINVAL;
  296. err = nla_parse_nested(tb, SEG6_IPTUNNEL_MAX, nla,
  297. seg6_iptunnel_policy, extack);
  298. if (err < 0)
  299. return err;
  300. if (!tb[SEG6_IPTUNNEL_SRH])
  301. return -EINVAL;
  302. tuninfo = nla_data(tb[SEG6_IPTUNNEL_SRH]);
  303. tuninfo_len = nla_len(tb[SEG6_IPTUNNEL_SRH]);
  304. /* tuninfo must contain at least the iptunnel encap structure,
  305. * the SRH and one segment
  306. */
  307. min_size = sizeof(*tuninfo) + sizeof(struct ipv6_sr_hdr) +
  308. sizeof(struct in6_addr);
  309. if (tuninfo_len < min_size)
  310. return -EINVAL;
  311. switch (tuninfo->mode) {
  312. case SEG6_IPTUN_MODE_INLINE:
  313. if (family != AF_INET6)
  314. return -EINVAL;
  315. break;
  316. case SEG6_IPTUN_MODE_ENCAP:
  317. break;
  318. case SEG6_IPTUN_MODE_L2ENCAP:
  319. break;
  320. default:
  321. return -EINVAL;
  322. }
  323. /* verify that SRH is consistent */
  324. if (!seg6_validate_srh(tuninfo->srh, tuninfo_len - sizeof(*tuninfo)))
  325. return -EINVAL;
  326. newts = lwtunnel_state_alloc(tuninfo_len + sizeof(*slwt));
  327. if (!newts)
  328. return -ENOMEM;
  329. slwt = seg6_lwt_lwtunnel(newts);
  330. err = dst_cache_init(&slwt->cache, GFP_KERNEL);
  331. if (err) {
  332. kfree(newts);
  333. return err;
  334. }
  335. memcpy(&slwt->tuninfo, tuninfo, tuninfo_len);
  336. newts->type = LWTUNNEL_ENCAP_SEG6;
  337. newts->flags |= LWTUNNEL_STATE_INPUT_REDIRECT;
  338. if (tuninfo->mode != SEG6_IPTUN_MODE_L2ENCAP)
  339. newts->flags |= LWTUNNEL_STATE_OUTPUT_REDIRECT;
  340. newts->headroom = seg6_lwt_headroom(tuninfo);
  341. *ts = newts;
  342. return 0;
  343. }
  344. static void seg6_destroy_state(struct lwtunnel_state *lwt)
  345. {
  346. dst_cache_destroy(&seg6_lwt_lwtunnel(lwt)->cache);
  347. }
  348. static int seg6_fill_encap_info(struct sk_buff *skb,
  349. struct lwtunnel_state *lwtstate)
  350. {
  351. struct seg6_iptunnel_encap *tuninfo = seg6_encap_lwtunnel(lwtstate);
  352. if (nla_put_srh(skb, SEG6_IPTUNNEL_SRH, tuninfo))
  353. return -EMSGSIZE;
  354. return 0;
  355. }
  356. static int seg6_encap_nlsize(struct lwtunnel_state *lwtstate)
  357. {
  358. struct seg6_iptunnel_encap *tuninfo = seg6_encap_lwtunnel(lwtstate);
  359. return nla_total_size(SEG6_IPTUN_ENCAP_SIZE(tuninfo));
  360. }
  361. static int seg6_encap_cmp(struct lwtunnel_state *a, struct lwtunnel_state *b)
  362. {
  363. struct seg6_iptunnel_encap *a_hdr = seg6_encap_lwtunnel(a);
  364. struct seg6_iptunnel_encap *b_hdr = seg6_encap_lwtunnel(b);
  365. int len = SEG6_IPTUN_ENCAP_SIZE(a_hdr);
  366. if (len != SEG6_IPTUN_ENCAP_SIZE(b_hdr))
  367. return 1;
  368. return memcmp(a_hdr, b_hdr, len);
  369. }
  370. static const struct lwtunnel_encap_ops seg6_iptun_ops = {
  371. .build_state = seg6_build_state,
  372. .destroy_state = seg6_destroy_state,
  373. .output = seg6_output,
  374. .input = seg6_input,
  375. .fill_encap = seg6_fill_encap_info,
  376. .get_encap_size = seg6_encap_nlsize,
  377. .cmp_encap = seg6_encap_cmp,
  378. .owner = THIS_MODULE,
  379. };
  380. int __init seg6_iptunnel_init(void)
  381. {
  382. return lwtunnel_encap_add_ops(&seg6_iptun_ops, LWTUNNEL_ENCAP_SEG6);
  383. }
  384. void seg6_iptunnel_exit(void)
  385. {
  386. lwtunnel_encap_del_ops(&seg6_iptun_ops, LWTUNNEL_ENCAP_SEG6);
  387. }