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 /* Compute flowlabel for outer IPv6 header */ 95 static __be32 seg6_make_flowlabel(struct net *net, struct sk_buff *skb, 96 struct ipv6hdr *inner_hdr) 97 { 98 int do_flowlabel = net->ipv6.sysctl.seg6_flowlabel; 99 __be32 flowlabel = 0; 100 u32 hash; 101 102 if (do_flowlabel > 0) { 103 hash = skb_get_hash(skb); 104 hash = rol32(hash, 16); 105 flowlabel = (__force __be32)hash & IPV6_FLOWLABEL_MASK; 106 } else if (!do_flowlabel && skb->protocol == htons(ETH_P_IPV6)) { 107 flowlabel = ip6_flowlabel(inner_hdr); 108 } 109 return flowlabel; 110 } 111 112 /* encapsulate an IPv6 packet within an outer IPv6 header with a given SRH */ 113 int seg6_do_srh_encap(struct sk_buff *skb, struct ipv6_sr_hdr *osrh, int proto) 114 { 115 struct dst_entry *dst = skb_dst(skb); 116 struct net *net = dev_net(dst->dev); 117 struct ipv6hdr *hdr, *inner_hdr; 118 struct ipv6_sr_hdr *isrh; 119 int hdrlen, tot_len, err; 120 __be32 flowlabel; 121 122 hdrlen = (osrh->hdrlen + 1) << 3; 123 tot_len = hdrlen + sizeof(*hdr); 124 125 err = skb_cow_head(skb, tot_len + skb->mac_len); 126 if (unlikely(err)) 127 return err; 128 129 inner_hdr = ipv6_hdr(skb); 130 flowlabel = seg6_make_flowlabel(net, skb, inner_hdr); 131 132 skb_push(skb, tot_len); 133 skb_reset_network_header(skb); 134 skb_mac_header_rebuild(skb); 135 hdr = ipv6_hdr(skb); 136 137 /* inherit tc, flowlabel and hlim 138 * hlim will be decremented in ip6_forward() afterwards and 139 * decapsulation will overwrite inner hlim with outer hlim 140 */ 141 142 if (skb->protocol == htons(ETH_P_IPV6)) { 143 ip6_flow_hdr(hdr, ip6_tclass(ip6_flowinfo(inner_hdr)), 144 flowlabel); 145 hdr->hop_limit = inner_hdr->hop_limit; 146 } else { 147 ip6_flow_hdr(hdr, 0, flowlabel); 148 hdr->hop_limit = ip6_dst_hoplimit(skb_dst(skb)); 149 150 memset(IP6CB(skb), 0, sizeof(*IP6CB(skb))); 151 } 152 153 hdr->nexthdr = NEXTHDR_ROUTING; 154 155 isrh = (void *)hdr + sizeof(*hdr); 156 memcpy(isrh, osrh, hdrlen); 157 158 isrh->nexthdr = proto; 159 160 hdr->daddr = isrh->segments[isrh->first_segment]; 161 set_tun_src(net, dst->dev, &hdr->daddr, &hdr->saddr); 162 163 #ifdef CONFIG_IPV6_SEG6_HMAC 164 if (sr_has_hmac(isrh)) { 165 err = seg6_push_hmac(net, &hdr->saddr, isrh); 166 if (unlikely(err)) 167 return err; 168 } 169 #endif 170 171 skb_postpush_rcsum(skb, hdr, tot_len); 172 173 return 0; 174 } 175 EXPORT_SYMBOL_GPL(seg6_do_srh_encap); 176 177 /* insert an SRH within an IPv6 packet, just after the IPv6 header */ 178 int seg6_do_srh_inline(struct sk_buff *skb, struct ipv6_sr_hdr *osrh) 179 { 180 struct ipv6hdr *hdr, *oldhdr; 181 struct ipv6_sr_hdr *isrh; 182 int hdrlen, err; 183 184 hdrlen = (osrh->hdrlen + 1) << 3; 185 186 err = skb_cow_head(skb, hdrlen + skb->mac_len); 187 if (unlikely(err)) 188 return err; 189 190 oldhdr = ipv6_hdr(skb); 191 192 skb_pull(skb, sizeof(struct ipv6hdr)); 193 skb_postpull_rcsum(skb, skb_network_header(skb), 194 sizeof(struct ipv6hdr)); 195 196 skb_push(skb, sizeof(struct ipv6hdr) + hdrlen); 197 skb_reset_network_header(skb); 198 skb_mac_header_rebuild(skb); 199 200 hdr = ipv6_hdr(skb); 201 202 memmove(hdr, oldhdr, sizeof(*hdr)); 203 204 isrh = (void *)hdr + sizeof(*hdr); 205 memcpy(isrh, osrh, hdrlen); 206 207 isrh->nexthdr = hdr->nexthdr; 208 hdr->nexthdr = NEXTHDR_ROUTING; 209 210 isrh->segments[0] = hdr->daddr; 211 hdr->daddr = isrh->segments[isrh->first_segment]; 212 213 #ifdef CONFIG_IPV6_SEG6_HMAC 214 if (sr_has_hmac(isrh)) { 215 struct net *net = dev_net(skb_dst(skb)->dev); 216 217 err = seg6_push_hmac(net, &hdr->saddr, isrh); 218 if (unlikely(err)) 219 return err; 220 } 221 #endif 222 223 skb_postpush_rcsum(skb, hdr, sizeof(struct ipv6hdr) + hdrlen); 224 225 return 0; 226 } 227 EXPORT_SYMBOL_GPL(seg6_do_srh_inline); 228 229 static int seg6_do_srh(struct sk_buff *skb) 230 { 231 struct dst_entry *dst = skb_dst(skb); 232 struct seg6_iptunnel_encap *tinfo; 233 int proto, err = 0; 234 235 tinfo = seg6_encap_lwtunnel(dst->lwtstate); 236 237 switch (tinfo->mode) { 238 case SEG6_IPTUN_MODE_INLINE: 239 if (skb->protocol != htons(ETH_P_IPV6)) 240 return -EINVAL; 241 242 err = seg6_do_srh_inline(skb, tinfo->srh); 243 if (err) 244 return err; 245 break; 246 case SEG6_IPTUN_MODE_ENCAP: 247 err = iptunnel_handle_offloads(skb, SKB_GSO_IPXIP6); 248 if (err) 249 return err; 250 251 if (skb->protocol == htons(ETH_P_IPV6)) 252 proto = IPPROTO_IPV6; 253 else if (skb->protocol == htons(ETH_P_IP)) 254 proto = IPPROTO_IPIP; 255 else 256 return -EINVAL; 257 258 err = seg6_do_srh_encap(skb, tinfo->srh, proto); 259 if (err) 260 return err; 261 262 skb_set_inner_transport_header(skb, skb_transport_offset(skb)); 263 skb_set_inner_protocol(skb, skb->protocol); 264 skb->protocol = htons(ETH_P_IPV6); 265 break; 266 case SEG6_IPTUN_MODE_L2ENCAP: 267 if (!skb_mac_header_was_set(skb)) 268 return -EINVAL; 269 270 if (pskb_expand_head(skb, skb->mac_len, 0, GFP_ATOMIC) < 0) 271 return -ENOMEM; 272 273 skb_mac_header_rebuild(skb); 274 skb_push(skb, skb->mac_len); 275 276 err = seg6_do_srh_encap(skb, tinfo->srh, NEXTHDR_NONE); 277 if (err) 278 return err; 279 280 skb->protocol = htons(ETH_P_IPV6); 281 break; 282 } 283 284 ipv6_hdr(skb)->payload_len = htons(skb->len - sizeof(struct ipv6hdr)); 285 skb_set_transport_header(skb, sizeof(struct ipv6hdr)); 286 287 return 0; 288 } 289 290 static int seg6_input(struct sk_buff *skb) 291 { 292 struct dst_entry *orig_dst = skb_dst(skb); 293 struct dst_entry *dst = NULL; 294 struct seg6_lwt *slwt; 295 int err; 296 297 err = seg6_do_srh(skb); 298 if (unlikely(err)) { 299 kfree_skb(skb); 300 return err; 301 } 302 303 slwt = seg6_lwt_lwtunnel(orig_dst->lwtstate); 304 305 preempt_disable(); 306 dst = dst_cache_get(&slwt->cache); 307 preempt_enable(); 308 309 skb_dst_drop(skb); 310 311 if (!dst) { 312 ip6_route_input(skb); 313 dst = skb_dst(skb); 314 if (!dst->error) { 315 preempt_disable(); 316 dst_cache_set_ip6(&slwt->cache, dst, 317 &ipv6_hdr(skb)->saddr); 318 preempt_enable(); 319 } 320 } else { 321 skb_dst_set(skb, dst); 322 } 323 324 err = skb_cow_head(skb, LL_RESERVED_SPACE(dst->dev)); 325 if (unlikely(err)) 326 return err; 327 328 return dst_input(skb); 329 } 330 331 static int seg6_output(struct net *net, struct sock *sk, struct sk_buff *skb) 332 { 333 struct dst_entry *orig_dst = skb_dst(skb); 334 struct dst_entry *dst = NULL; 335 struct seg6_lwt *slwt; 336 int err = -EINVAL; 337 338 err = seg6_do_srh(skb); 339 if (unlikely(err)) 340 goto drop; 341 342 slwt = seg6_lwt_lwtunnel(orig_dst->lwtstate); 343 344 preempt_disable(); 345 dst = dst_cache_get(&slwt->cache); 346 preempt_enable(); 347 348 if (unlikely(!dst)) { 349 struct ipv6hdr *hdr = ipv6_hdr(skb); 350 struct flowi6 fl6; 351 352 memset(&fl6, 0, sizeof(fl6)); 353 fl6.daddr = hdr->daddr; 354 fl6.saddr = hdr->saddr; 355 fl6.flowlabel = ip6_flowinfo(hdr); 356 fl6.flowi6_mark = skb->mark; 357 fl6.flowi6_proto = hdr->nexthdr; 358 359 dst = ip6_route_output(net, NULL, &fl6); 360 if (dst->error) { 361 err = dst->error; 362 dst_release(dst); 363 goto drop; 364 } 365 366 preempt_disable(); 367 dst_cache_set_ip6(&slwt->cache, dst, &fl6.saddr); 368 preempt_enable(); 369 } 370 371 skb_dst_drop(skb); 372 skb_dst_set(skb, dst); 373 374 err = skb_cow_head(skb, LL_RESERVED_SPACE(dst->dev)); 375 if (unlikely(err)) 376 goto drop; 377 378 return dst_output(net, sk, skb); 379 drop: 380 kfree_skb(skb); 381 return err; 382 } 383 384 static int seg6_build_state(struct nlattr *nla, 385 unsigned int family, const void *cfg, 386 struct lwtunnel_state **ts, 387 struct netlink_ext_ack *extack) 388 { 389 struct nlattr *tb[SEG6_IPTUNNEL_MAX + 1]; 390 struct seg6_iptunnel_encap *tuninfo; 391 struct lwtunnel_state *newts; 392 int tuninfo_len, min_size; 393 struct seg6_lwt *slwt; 394 int err; 395 396 if (family != AF_INET && family != AF_INET6) 397 return -EINVAL; 398 399 err = nla_parse_nested(tb, SEG6_IPTUNNEL_MAX, nla, 400 seg6_iptunnel_policy, extack); 401 402 if (err < 0) 403 return err; 404 405 if (!tb[SEG6_IPTUNNEL_SRH]) 406 return -EINVAL; 407 408 tuninfo = nla_data(tb[SEG6_IPTUNNEL_SRH]); 409 tuninfo_len = nla_len(tb[SEG6_IPTUNNEL_SRH]); 410 411 /* tuninfo must contain at least the iptunnel encap structure, 412 * the SRH and one segment 413 */ 414 min_size = sizeof(*tuninfo) + sizeof(struct ipv6_sr_hdr) + 415 sizeof(struct in6_addr); 416 if (tuninfo_len < min_size) 417 return -EINVAL; 418 419 switch (tuninfo->mode) { 420 case SEG6_IPTUN_MODE_INLINE: 421 if (family != AF_INET6) 422 return -EINVAL; 423 424 break; 425 case SEG6_IPTUN_MODE_ENCAP: 426 break; 427 case SEG6_IPTUN_MODE_L2ENCAP: 428 break; 429 default: 430 return -EINVAL; 431 } 432 433 /* verify that SRH is consistent */ 434 if (!seg6_validate_srh(tuninfo->srh, tuninfo_len - sizeof(*tuninfo))) 435 return -EINVAL; 436 437 newts = lwtunnel_state_alloc(tuninfo_len + sizeof(*slwt)); 438 if (!newts) 439 return -ENOMEM; 440 441 slwt = seg6_lwt_lwtunnel(newts); 442 443 err = dst_cache_init(&slwt->cache, GFP_ATOMIC); 444 if (err) { 445 kfree(newts); 446 return err; 447 } 448 449 memcpy(&slwt->tuninfo, tuninfo, tuninfo_len); 450 451 newts->type = LWTUNNEL_ENCAP_SEG6; 452 newts->flags |= LWTUNNEL_STATE_INPUT_REDIRECT; 453 454 if (tuninfo->mode != SEG6_IPTUN_MODE_L2ENCAP) 455 newts->flags |= LWTUNNEL_STATE_OUTPUT_REDIRECT; 456 457 newts->headroom = seg6_lwt_headroom(tuninfo); 458 459 *ts = newts; 460 461 return 0; 462 } 463 464 static void seg6_destroy_state(struct lwtunnel_state *lwt) 465 { 466 dst_cache_destroy(&seg6_lwt_lwtunnel(lwt)->cache); 467 } 468 469 static int seg6_fill_encap_info(struct sk_buff *skb, 470 struct lwtunnel_state *lwtstate) 471 { 472 struct seg6_iptunnel_encap *tuninfo = seg6_encap_lwtunnel(lwtstate); 473 474 if (nla_put_srh(skb, SEG6_IPTUNNEL_SRH, tuninfo)) 475 return -EMSGSIZE; 476 477 return 0; 478 } 479 480 static int seg6_encap_nlsize(struct lwtunnel_state *lwtstate) 481 { 482 struct seg6_iptunnel_encap *tuninfo = seg6_encap_lwtunnel(lwtstate); 483 484 return nla_total_size(SEG6_IPTUN_ENCAP_SIZE(tuninfo)); 485 } 486 487 static int seg6_encap_cmp(struct lwtunnel_state *a, struct lwtunnel_state *b) 488 { 489 struct seg6_iptunnel_encap *a_hdr = seg6_encap_lwtunnel(a); 490 struct seg6_iptunnel_encap *b_hdr = seg6_encap_lwtunnel(b); 491 int len = SEG6_IPTUN_ENCAP_SIZE(a_hdr); 492 493 if (len != SEG6_IPTUN_ENCAP_SIZE(b_hdr)) 494 return 1; 495 496 return memcmp(a_hdr, b_hdr, len); 497 } 498 499 static const struct lwtunnel_encap_ops seg6_iptun_ops = { 500 .build_state = seg6_build_state, 501 .destroy_state = seg6_destroy_state, 502 .output = seg6_output, 503 .input = seg6_input, 504 .fill_encap = seg6_fill_encap_info, 505 .get_encap_size = seg6_encap_nlsize, 506 .cmp_encap = seg6_encap_cmp, 507 .owner = THIS_MODULE, 508 }; 509 510 int __init seg6_iptunnel_init(void) 511 { 512 return lwtunnel_encap_add_ops(&seg6_iptun_ops, LWTUNNEL_ENCAP_SEG6); 513 } 514 515 void seg6_iptunnel_exit(void) 516 { 517 lwtunnel_encap_del_ops(&seg6_iptun_ops, LWTUNNEL_ENCAP_SEG6); 518 } 519