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