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 14 #include <linux/types.h> 15 #include <linux/skbuff.h> 16 #include <linux/net.h> 17 #include <linux/module.h> 18 #include <net/ip.h> 19 #include <net/ip_tunnels.h> 20 #include <net/lwtunnel.h> 21 #include <net/netevent.h> 22 #include <net/netns/generic.h> 23 #include <net/ip6_fib.h> 24 #include <net/route.h> 25 #include <net/seg6.h> 26 #include <linux/seg6.h> 27 #include <linux/seg6_iptunnel.h> 28 #include <net/addrconf.h> 29 #include <net/ip6_route.h> 30 #include <net/dst_cache.h> 31 #ifdef CONFIG_IPV6_SEG6_HMAC 32 #include <net/seg6_hmac.h> 33 #endif 34 35 struct seg6_lwt { 36 struct dst_cache cache; 37 struct seg6_iptunnel_encap tuninfo[0]; 38 }; 39 40 static inline struct seg6_lwt *seg6_lwt_lwtunnel(struct lwtunnel_state *lwt) 41 { 42 return (struct seg6_lwt *)lwt->data; 43 } 44 45 static inline struct seg6_iptunnel_encap * 46 seg6_encap_lwtunnel(struct lwtunnel_state *lwt) 47 { 48 return seg6_lwt_lwtunnel(lwt)->tuninfo; 49 } 50 51 static const struct nla_policy seg6_iptunnel_policy[SEG6_IPTUNNEL_MAX + 1] = { 52 [SEG6_IPTUNNEL_SRH] = { .type = NLA_BINARY }, 53 }; 54 55 static int nla_put_srh(struct sk_buff *skb, int attrtype, 56 struct seg6_iptunnel_encap *tuninfo) 57 { 58 struct seg6_iptunnel_encap *data; 59 struct nlattr *nla; 60 int len; 61 62 len = SEG6_IPTUN_ENCAP_SIZE(tuninfo); 63 64 nla = nla_reserve(skb, attrtype, len); 65 if (!nla) 66 return -EMSGSIZE; 67 68 data = nla_data(nla); 69 memcpy(data, tuninfo, len); 70 71 return 0; 72 } 73 74 static void set_tun_src(struct net *net, struct net_device *dev, 75 struct in6_addr *daddr, struct in6_addr *saddr) 76 { 77 struct seg6_pernet_data *sdata = seg6_pernet(net); 78 struct in6_addr *tun_src; 79 80 rcu_read_lock(); 81 82 tun_src = rcu_dereference(sdata->tun_src); 83 84 if (!ipv6_addr_any(tun_src)) { 85 memcpy(saddr, tun_src, sizeof(struct in6_addr)); 86 } else { 87 ipv6_dev_get_saddr(net, dev, daddr, IPV6_PREFER_SRC_PUBLIC, 88 saddr); 89 } 90 91 rcu_read_unlock(); 92 } 93 94 /* encapsulate an IPv6 packet within an outer IPv6 header with a given SRH */ 95 int seg6_do_srh_encap(struct sk_buff *skb, struct ipv6_sr_hdr *osrh, int proto) 96 { 97 struct dst_entry *dst = skb_dst(skb); 98 struct net *net = dev_net(dst->dev); 99 struct ipv6hdr *hdr, *inner_hdr; 100 struct ipv6_sr_hdr *isrh; 101 int hdrlen, tot_len, err; 102 103 hdrlen = (osrh->hdrlen + 1) << 3; 104 tot_len = hdrlen + sizeof(*hdr); 105 106 err = skb_cow_head(skb, tot_len); 107 if (unlikely(err)) 108 return err; 109 110 inner_hdr = ipv6_hdr(skb); 111 112 skb_push(skb, tot_len); 113 skb_reset_network_header(skb); 114 skb_mac_header_rebuild(skb); 115 hdr = ipv6_hdr(skb); 116 117 /* inherit tc, flowlabel and hlim 118 * hlim will be decremented in ip6_forward() afterwards and 119 * decapsulation will overwrite inner hlim with outer hlim 120 */ 121 122 if (skb->protocol == htons(ETH_P_IPV6)) { 123 ip6_flow_hdr(hdr, ip6_tclass(ip6_flowinfo(inner_hdr)), 124 ip6_flowlabel(inner_hdr)); 125 hdr->hop_limit = inner_hdr->hop_limit; 126 } else { 127 ip6_flow_hdr(hdr, 0, 0); 128 hdr->hop_limit = ip6_dst_hoplimit(skb_dst(skb)); 129 } 130 131 hdr->nexthdr = NEXTHDR_ROUTING; 132 133 isrh = (void *)hdr + sizeof(*hdr); 134 memcpy(isrh, osrh, hdrlen); 135 136 isrh->nexthdr = proto; 137 138 hdr->daddr = isrh->segments[isrh->first_segment]; 139 set_tun_src(net, dst->dev, &hdr->daddr, &hdr->saddr); 140 141 #ifdef CONFIG_IPV6_SEG6_HMAC 142 if (sr_has_hmac(isrh)) { 143 err = seg6_push_hmac(net, &hdr->saddr, isrh); 144 if (unlikely(err)) 145 return err; 146 } 147 #endif 148 149 skb_postpush_rcsum(skb, hdr, tot_len); 150 151 return 0; 152 } 153 EXPORT_SYMBOL_GPL(seg6_do_srh_encap); 154 155 /* insert an SRH within an IPv6 packet, just after the IPv6 header */ 156 int seg6_do_srh_inline(struct sk_buff *skb, struct ipv6_sr_hdr *osrh) 157 { 158 struct ipv6hdr *hdr, *oldhdr; 159 struct ipv6_sr_hdr *isrh; 160 int hdrlen, err; 161 162 hdrlen = (osrh->hdrlen + 1) << 3; 163 164 err = skb_cow_head(skb, hdrlen); 165 if (unlikely(err)) 166 return err; 167 168 oldhdr = ipv6_hdr(skb); 169 170 skb_pull(skb, sizeof(struct ipv6hdr)); 171 skb_postpull_rcsum(skb, skb_network_header(skb), 172 sizeof(struct ipv6hdr)); 173 174 skb_push(skb, sizeof(struct ipv6hdr) + hdrlen); 175 skb_reset_network_header(skb); 176 skb_mac_header_rebuild(skb); 177 178 hdr = ipv6_hdr(skb); 179 180 memmove(hdr, oldhdr, sizeof(*hdr)); 181 182 isrh = (void *)hdr + sizeof(*hdr); 183 memcpy(isrh, osrh, hdrlen); 184 185 isrh->nexthdr = hdr->nexthdr; 186 hdr->nexthdr = NEXTHDR_ROUTING; 187 188 isrh->segments[0] = hdr->daddr; 189 hdr->daddr = isrh->segments[isrh->first_segment]; 190 191 #ifdef CONFIG_IPV6_SEG6_HMAC 192 if (sr_has_hmac(isrh)) { 193 struct net *net = dev_net(skb_dst(skb)->dev); 194 195 err = seg6_push_hmac(net, &hdr->saddr, isrh); 196 if (unlikely(err)) 197 return err; 198 } 199 #endif 200 201 skb_postpush_rcsum(skb, hdr, sizeof(struct ipv6hdr) + hdrlen); 202 203 return 0; 204 } 205 EXPORT_SYMBOL_GPL(seg6_do_srh_inline); 206 207 static int seg6_do_srh(struct sk_buff *skb) 208 { 209 struct dst_entry *dst = skb_dst(skb); 210 struct seg6_iptunnel_encap *tinfo; 211 int proto, err = 0; 212 213 tinfo = seg6_encap_lwtunnel(dst->lwtstate); 214 215 switch (tinfo->mode) { 216 case SEG6_IPTUN_MODE_INLINE: 217 if (skb->protocol != htons(ETH_P_IPV6)) 218 return -EINVAL; 219 220 err = seg6_do_srh_inline(skb, tinfo->srh); 221 if (err) 222 return err; 223 break; 224 case SEG6_IPTUN_MODE_ENCAP: 225 err = iptunnel_handle_offloads(skb, SKB_GSO_IPXIP6); 226 if (err) 227 return err; 228 229 if (skb->protocol == htons(ETH_P_IPV6)) 230 proto = IPPROTO_IPV6; 231 else if (skb->protocol == htons(ETH_P_IP)) 232 proto = IPPROTO_IPIP; 233 else 234 return -EINVAL; 235 236 err = seg6_do_srh_encap(skb, tinfo->srh, proto); 237 if (err) 238 return err; 239 240 skb_set_inner_transport_header(skb, skb_transport_offset(skb)); 241 skb_set_inner_protocol(skb, skb->protocol); 242 skb->protocol = htons(ETH_P_IPV6); 243 break; 244 case SEG6_IPTUN_MODE_L2ENCAP: 245 if (!skb_mac_header_was_set(skb)) 246 return -EINVAL; 247 248 if (pskb_expand_head(skb, skb->mac_len, 0, GFP_ATOMIC) < 0) 249 return -ENOMEM; 250 251 skb_mac_header_rebuild(skb); 252 skb_push(skb, skb->mac_len); 253 254 err = seg6_do_srh_encap(skb, tinfo->srh, NEXTHDR_NONE); 255 if (err) 256 return err; 257 258 skb->protocol = htons(ETH_P_IPV6); 259 break; 260 } 261 262 ipv6_hdr(skb)->payload_len = htons(skb->len - sizeof(struct ipv6hdr)); 263 skb_set_transport_header(skb, sizeof(struct ipv6hdr)); 264 265 return 0; 266 } 267 268 static int seg6_input(struct sk_buff *skb) 269 { 270 struct dst_entry *orig_dst = skb_dst(skb); 271 struct dst_entry *dst = NULL; 272 struct seg6_lwt *slwt; 273 int err; 274 275 err = seg6_do_srh(skb); 276 if (unlikely(err)) { 277 kfree_skb(skb); 278 return err; 279 } 280 281 slwt = seg6_lwt_lwtunnel(orig_dst->lwtstate); 282 283 preempt_disable(); 284 dst = dst_cache_get(&slwt->cache); 285 preempt_enable(); 286 287 skb_dst_drop(skb); 288 289 if (!dst) { 290 ip6_route_input(skb); 291 dst = skb_dst(skb); 292 if (!dst->error) { 293 preempt_disable(); 294 dst_cache_set_ip6(&slwt->cache, dst, 295 &ipv6_hdr(skb)->saddr); 296 preempt_enable(); 297 } 298 } else { 299 skb_dst_set(skb, dst); 300 } 301 302 err = skb_cow_head(skb, LL_RESERVED_SPACE(dst->dev)); 303 if (unlikely(err)) 304 return err; 305 306 return dst_input(skb); 307 } 308 309 static int seg6_output(struct net *net, struct sock *sk, struct sk_buff *skb) 310 { 311 struct dst_entry *orig_dst = skb_dst(skb); 312 struct dst_entry *dst = NULL; 313 struct seg6_lwt *slwt; 314 int err = -EINVAL; 315 316 err = seg6_do_srh(skb); 317 if (unlikely(err)) 318 goto drop; 319 320 slwt = seg6_lwt_lwtunnel(orig_dst->lwtstate); 321 322 preempt_disable(); 323 dst = dst_cache_get(&slwt->cache); 324 preempt_enable(); 325 326 if (unlikely(!dst)) { 327 struct ipv6hdr *hdr = ipv6_hdr(skb); 328 struct flowi6 fl6; 329 330 fl6.daddr = hdr->daddr; 331 fl6.saddr = hdr->saddr; 332 fl6.flowlabel = ip6_flowinfo(hdr); 333 fl6.flowi6_mark = skb->mark; 334 fl6.flowi6_proto = hdr->nexthdr; 335 336 dst = ip6_route_output(net, NULL, &fl6); 337 if (dst->error) { 338 err = dst->error; 339 dst_release(dst); 340 goto drop; 341 } 342 343 preempt_disable(); 344 dst_cache_set_ip6(&slwt->cache, dst, &fl6.saddr); 345 preempt_enable(); 346 } 347 348 skb_dst_drop(skb); 349 skb_dst_set(skb, dst); 350 351 err = skb_cow_head(skb, LL_RESERVED_SPACE(dst->dev)); 352 if (unlikely(err)) 353 goto drop; 354 355 return dst_output(net, sk, skb); 356 drop: 357 kfree_skb(skb); 358 return err; 359 } 360 361 static int seg6_build_state(struct nlattr *nla, 362 unsigned int family, const void *cfg, 363 struct lwtunnel_state **ts, 364 struct netlink_ext_ack *extack) 365 { 366 struct nlattr *tb[SEG6_IPTUNNEL_MAX + 1]; 367 struct seg6_iptunnel_encap *tuninfo; 368 struct lwtunnel_state *newts; 369 int tuninfo_len, min_size; 370 struct seg6_lwt *slwt; 371 int err; 372 373 if (family != AF_INET && family != AF_INET6) 374 return -EINVAL; 375 376 err = nla_parse_nested(tb, SEG6_IPTUNNEL_MAX, nla, 377 seg6_iptunnel_policy, extack); 378 379 if (err < 0) 380 return err; 381 382 if (!tb[SEG6_IPTUNNEL_SRH]) 383 return -EINVAL; 384 385 tuninfo = nla_data(tb[SEG6_IPTUNNEL_SRH]); 386 tuninfo_len = nla_len(tb[SEG6_IPTUNNEL_SRH]); 387 388 /* tuninfo must contain at least the iptunnel encap structure, 389 * the SRH and one segment 390 */ 391 min_size = sizeof(*tuninfo) + sizeof(struct ipv6_sr_hdr) + 392 sizeof(struct in6_addr); 393 if (tuninfo_len < min_size) 394 return -EINVAL; 395 396 switch (tuninfo->mode) { 397 case SEG6_IPTUN_MODE_INLINE: 398 if (family != AF_INET6) 399 return -EINVAL; 400 401 break; 402 case SEG6_IPTUN_MODE_ENCAP: 403 break; 404 case SEG6_IPTUN_MODE_L2ENCAP: 405 break; 406 default: 407 return -EINVAL; 408 } 409 410 /* verify that SRH is consistent */ 411 if (!seg6_validate_srh(tuninfo->srh, tuninfo_len - sizeof(*tuninfo))) 412 return -EINVAL; 413 414 newts = lwtunnel_state_alloc(tuninfo_len + sizeof(*slwt)); 415 if (!newts) 416 return -ENOMEM; 417 418 slwt = seg6_lwt_lwtunnel(newts); 419 420 err = dst_cache_init(&slwt->cache, GFP_ATOMIC); 421 if (err) { 422 kfree(newts); 423 return err; 424 } 425 426 memcpy(&slwt->tuninfo, tuninfo, tuninfo_len); 427 428 newts->type = LWTUNNEL_ENCAP_SEG6; 429 newts->flags |= LWTUNNEL_STATE_INPUT_REDIRECT; 430 431 if (tuninfo->mode != SEG6_IPTUN_MODE_L2ENCAP) 432 newts->flags |= LWTUNNEL_STATE_OUTPUT_REDIRECT; 433 434 newts->headroom = seg6_lwt_headroom(tuninfo); 435 436 *ts = newts; 437 438 return 0; 439 } 440 441 static void seg6_destroy_state(struct lwtunnel_state *lwt) 442 { 443 dst_cache_destroy(&seg6_lwt_lwtunnel(lwt)->cache); 444 } 445 446 static int seg6_fill_encap_info(struct sk_buff *skb, 447 struct lwtunnel_state *lwtstate) 448 { 449 struct seg6_iptunnel_encap *tuninfo = seg6_encap_lwtunnel(lwtstate); 450 451 if (nla_put_srh(skb, SEG6_IPTUNNEL_SRH, tuninfo)) 452 return -EMSGSIZE; 453 454 return 0; 455 } 456 457 static int seg6_encap_nlsize(struct lwtunnel_state *lwtstate) 458 { 459 struct seg6_iptunnel_encap *tuninfo = seg6_encap_lwtunnel(lwtstate); 460 461 return nla_total_size(SEG6_IPTUN_ENCAP_SIZE(tuninfo)); 462 } 463 464 static int seg6_encap_cmp(struct lwtunnel_state *a, struct lwtunnel_state *b) 465 { 466 struct seg6_iptunnel_encap *a_hdr = seg6_encap_lwtunnel(a); 467 struct seg6_iptunnel_encap *b_hdr = seg6_encap_lwtunnel(b); 468 int len = SEG6_IPTUN_ENCAP_SIZE(a_hdr); 469 470 if (len != SEG6_IPTUN_ENCAP_SIZE(b_hdr)) 471 return 1; 472 473 return memcmp(a_hdr, b_hdr, len); 474 } 475 476 static const struct lwtunnel_encap_ops seg6_iptun_ops = { 477 .build_state = seg6_build_state, 478 .destroy_state = seg6_destroy_state, 479 .output = seg6_output, 480 .input = seg6_input, 481 .fill_encap = seg6_fill_encap_info, 482 .get_encap_size = seg6_encap_nlsize, 483 .cmp_encap = seg6_encap_cmp, 484 .owner = THIS_MODULE, 485 }; 486 487 int __init seg6_iptunnel_init(void) 488 { 489 return lwtunnel_encap_add_ops(&seg6_iptun_ops, LWTUNNEL_ENCAP_SEG6); 490 } 491 492 void seg6_iptunnel_exit(void) 493 { 494 lwtunnel_encap_del_ops(&seg6_iptun_ops, LWTUNNEL_ENCAP_SEG6); 495 } 496