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/lwtunnel.h> 20 #include <net/netevent.h> 21 #include <net/netns/generic.h> 22 #include <net/ip6_fib.h> 23 #include <net/route.h> 24 #include <net/seg6.h> 25 #include <linux/seg6.h> 26 #include <linux/seg6_iptunnel.h> 27 #include <net/addrconf.h> 28 #include <net/ip6_route.h> 29 #include <net/dst_cache.h> 30 #ifdef CONFIG_IPV6_SEG6_HMAC 31 #include <net/seg6_hmac.h> 32 #endif 33 34 struct seg6_lwt { 35 struct dst_cache cache; 36 struct seg6_iptunnel_encap tuninfo[0]; 37 }; 38 39 static inline struct seg6_lwt *seg6_lwt_lwtunnel(struct lwtunnel_state *lwt) 40 { 41 return (struct seg6_lwt *)lwt->data; 42 } 43 44 static inline struct seg6_iptunnel_encap * 45 seg6_encap_lwtunnel(struct lwtunnel_state *lwt) 46 { 47 return seg6_lwt_lwtunnel(lwt)->tuninfo; 48 } 49 50 static const struct nla_policy seg6_iptunnel_policy[SEG6_IPTUNNEL_MAX + 1] = { 51 [SEG6_IPTUNNEL_SRH] = { .type = NLA_BINARY }, 52 }; 53 54 static int nla_put_srh(struct sk_buff *skb, int attrtype, 55 struct seg6_iptunnel_encap *tuninfo) 56 { 57 struct seg6_iptunnel_encap *data; 58 struct nlattr *nla; 59 int len; 60 61 len = SEG6_IPTUN_ENCAP_SIZE(tuninfo); 62 63 nla = nla_reserve(skb, attrtype, len); 64 if (!nla) 65 return -EMSGSIZE; 66 67 data = nla_data(nla); 68 memcpy(data, tuninfo, len); 69 70 return 0; 71 } 72 73 static void set_tun_src(struct net *net, struct net_device *dev, 74 struct in6_addr *daddr, struct in6_addr *saddr) 75 { 76 struct seg6_pernet_data *sdata = seg6_pernet(net); 77 struct in6_addr *tun_src; 78 79 rcu_read_lock(); 80 81 tun_src = rcu_dereference(sdata->tun_src); 82 83 if (!ipv6_addr_any(tun_src)) { 84 memcpy(saddr, tun_src, sizeof(struct in6_addr)); 85 } else { 86 ipv6_dev_get_saddr(net, dev, daddr, IPV6_PREFER_SRC_PUBLIC, 87 saddr); 88 } 89 90 rcu_read_unlock(); 91 } 92 93 /* encapsulate an IPv6 packet within an outer IPv6 header with a given SRH */ 94 static int seg6_do_srh_encap(struct sk_buff *skb, struct ipv6_sr_hdr *osrh) 95 { 96 struct net *net = dev_net(skb_dst(skb)->dev); 97 struct ipv6hdr *hdr, *inner_hdr; 98 struct ipv6_sr_hdr *isrh; 99 int hdrlen, tot_len, err; 100 101 hdrlen = (osrh->hdrlen + 1) << 3; 102 tot_len = hdrlen + sizeof(*hdr); 103 104 err = skb_cow_head(skb, tot_len); 105 if (unlikely(err)) 106 return err; 107 108 inner_hdr = ipv6_hdr(skb); 109 110 skb_push(skb, tot_len); 111 skb_reset_network_header(skb); 112 skb_mac_header_rebuild(skb); 113 hdr = ipv6_hdr(skb); 114 115 /* inherit tc, flowlabel and hlim 116 * hlim will be decremented in ip6_forward() afterwards and 117 * decapsulation will overwrite inner hlim with outer hlim 118 */ 119 ip6_flow_hdr(hdr, ip6_tclass(ip6_flowinfo(inner_hdr)), 120 ip6_flowlabel(inner_hdr)); 121 hdr->hop_limit = inner_hdr->hop_limit; 122 hdr->nexthdr = NEXTHDR_ROUTING; 123 124 isrh = (void *)hdr + sizeof(*hdr); 125 memcpy(isrh, osrh, hdrlen); 126 127 isrh->nexthdr = NEXTHDR_IPV6; 128 129 hdr->daddr = isrh->segments[isrh->first_segment]; 130 set_tun_src(net, skb->dev, &hdr->daddr, &hdr->saddr); 131 132 #ifdef CONFIG_IPV6_SEG6_HMAC 133 if (sr_has_hmac(isrh)) { 134 err = seg6_push_hmac(net, &hdr->saddr, isrh); 135 if (unlikely(err)) 136 return err; 137 } 138 #endif 139 140 skb_postpush_rcsum(skb, hdr, tot_len); 141 142 return 0; 143 } 144 145 /* insert an SRH within an IPv6 packet, just after the IPv6 header */ 146 #ifdef CONFIG_IPV6_SEG6_INLINE 147 static int seg6_do_srh_inline(struct sk_buff *skb, struct ipv6_sr_hdr *osrh) 148 { 149 struct ipv6hdr *hdr, *oldhdr; 150 struct ipv6_sr_hdr *isrh; 151 int hdrlen, err; 152 153 hdrlen = (osrh->hdrlen + 1) << 3; 154 155 err = skb_cow_head(skb, hdrlen); 156 if (unlikely(err)) 157 return err; 158 159 oldhdr = ipv6_hdr(skb); 160 161 skb_pull(skb, sizeof(struct ipv6hdr)); 162 skb_postpull_rcsum(skb, skb_network_header(skb), 163 sizeof(struct ipv6hdr)); 164 165 skb_push(skb, sizeof(struct ipv6hdr) + hdrlen); 166 skb_reset_network_header(skb); 167 skb_mac_header_rebuild(skb); 168 169 hdr = ipv6_hdr(skb); 170 171 memmove(hdr, oldhdr, sizeof(*hdr)); 172 173 isrh = (void *)hdr + sizeof(*hdr); 174 memcpy(isrh, osrh, hdrlen); 175 176 isrh->nexthdr = hdr->nexthdr; 177 hdr->nexthdr = NEXTHDR_ROUTING; 178 179 isrh->segments[0] = hdr->daddr; 180 hdr->daddr = isrh->segments[isrh->first_segment]; 181 182 #ifdef CONFIG_IPV6_SEG6_HMAC 183 if (sr_has_hmac(isrh)) { 184 struct net *net = dev_net(skb_dst(skb)->dev); 185 186 err = seg6_push_hmac(net, &hdr->saddr, isrh); 187 if (unlikely(err)) 188 return err; 189 } 190 #endif 191 192 skb_postpush_rcsum(skb, hdr, sizeof(struct ipv6hdr) + hdrlen); 193 194 return 0; 195 } 196 #endif 197 198 static int seg6_do_srh(struct sk_buff *skb) 199 { 200 struct dst_entry *dst = skb_dst(skb); 201 struct seg6_iptunnel_encap *tinfo; 202 int err = 0; 203 204 tinfo = seg6_encap_lwtunnel(dst->lwtstate); 205 206 if (likely(!skb->encapsulation)) { 207 skb_reset_inner_headers(skb); 208 skb->encapsulation = 1; 209 } 210 211 switch (tinfo->mode) { 212 #ifdef CONFIG_IPV6_SEG6_INLINE 213 case SEG6_IPTUN_MODE_INLINE: 214 err = seg6_do_srh_inline(skb, tinfo->srh); 215 skb_reset_inner_headers(skb); 216 break; 217 #endif 218 case SEG6_IPTUN_MODE_ENCAP: 219 err = seg6_do_srh_encap(skb, tinfo->srh); 220 break; 221 } 222 223 if (err) 224 return err; 225 226 ipv6_hdr(skb)->payload_len = htons(skb->len - sizeof(struct ipv6hdr)); 227 skb_set_transport_header(skb, sizeof(struct ipv6hdr)); 228 229 skb_set_inner_protocol(skb, skb->protocol); 230 231 return 0; 232 } 233 234 static int seg6_input(struct sk_buff *skb) 235 { 236 struct dst_entry *orig_dst = skb_dst(skb); 237 struct dst_entry *dst = NULL; 238 struct seg6_lwt *slwt; 239 int err; 240 241 err = seg6_do_srh(skb); 242 if (unlikely(err)) { 243 kfree_skb(skb); 244 return err; 245 } 246 247 slwt = seg6_lwt_lwtunnel(orig_dst->lwtstate); 248 249 preempt_disable(); 250 dst = dst_cache_get(&slwt->cache); 251 preempt_enable(); 252 253 skb_dst_drop(skb); 254 255 if (!dst) { 256 ip6_route_input(skb); 257 dst = skb_dst(skb); 258 if (!dst->error) { 259 preempt_disable(); 260 dst_cache_set_ip6(&slwt->cache, dst, 261 &ipv6_hdr(skb)->saddr); 262 preempt_enable(); 263 } 264 } else { 265 skb_dst_set(skb, dst); 266 } 267 268 err = skb_cow_head(skb, LL_RESERVED_SPACE(dst->dev)); 269 if (unlikely(err)) 270 return err; 271 272 return dst_input(skb); 273 } 274 275 static int seg6_output(struct net *net, struct sock *sk, struct sk_buff *skb) 276 { 277 struct dst_entry *orig_dst = skb_dst(skb); 278 struct dst_entry *dst = NULL; 279 struct seg6_lwt *slwt; 280 int err = -EINVAL; 281 282 err = seg6_do_srh(skb); 283 if (unlikely(err)) 284 goto drop; 285 286 slwt = seg6_lwt_lwtunnel(orig_dst->lwtstate); 287 288 preempt_disable(); 289 dst = dst_cache_get(&slwt->cache); 290 preempt_enable(); 291 292 if (unlikely(!dst)) { 293 struct ipv6hdr *hdr = ipv6_hdr(skb); 294 struct flowi6 fl6; 295 296 fl6.daddr = hdr->daddr; 297 fl6.saddr = hdr->saddr; 298 fl6.flowlabel = ip6_flowinfo(hdr); 299 fl6.flowi6_mark = skb->mark; 300 fl6.flowi6_proto = hdr->nexthdr; 301 302 dst = ip6_route_output(net, NULL, &fl6); 303 if (dst->error) { 304 err = dst->error; 305 dst_release(dst); 306 goto drop; 307 } 308 309 preempt_disable(); 310 dst_cache_set_ip6(&slwt->cache, dst, &fl6.saddr); 311 preempt_enable(); 312 } 313 314 skb_dst_drop(skb); 315 skb_dst_set(skb, dst); 316 317 err = skb_cow_head(skb, LL_RESERVED_SPACE(dst->dev)); 318 if (unlikely(err)) 319 goto drop; 320 321 return dst_output(net, sk, skb); 322 drop: 323 kfree_skb(skb); 324 return err; 325 } 326 327 static int seg6_build_state(struct nlattr *nla, 328 unsigned int family, const void *cfg, 329 struct lwtunnel_state **ts) 330 { 331 struct nlattr *tb[SEG6_IPTUNNEL_MAX + 1]; 332 struct seg6_iptunnel_encap *tuninfo; 333 struct lwtunnel_state *newts; 334 int tuninfo_len, min_size; 335 struct seg6_lwt *slwt; 336 int err; 337 338 err = nla_parse_nested(tb, SEG6_IPTUNNEL_MAX, nla, 339 seg6_iptunnel_policy, NULL); 340 341 if (err < 0) 342 return err; 343 344 if (!tb[SEG6_IPTUNNEL_SRH]) 345 return -EINVAL; 346 347 tuninfo = nla_data(tb[SEG6_IPTUNNEL_SRH]); 348 tuninfo_len = nla_len(tb[SEG6_IPTUNNEL_SRH]); 349 350 /* tuninfo must contain at least the iptunnel encap structure, 351 * the SRH and one segment 352 */ 353 min_size = sizeof(*tuninfo) + sizeof(struct ipv6_sr_hdr) + 354 sizeof(struct in6_addr); 355 if (tuninfo_len < min_size) 356 return -EINVAL; 357 358 switch (tuninfo->mode) { 359 #ifdef CONFIG_IPV6_SEG6_INLINE 360 case SEG6_IPTUN_MODE_INLINE: 361 break; 362 #endif 363 case SEG6_IPTUN_MODE_ENCAP: 364 break; 365 default: 366 return -EINVAL; 367 } 368 369 /* verify that SRH is consistent */ 370 if (!seg6_validate_srh(tuninfo->srh, tuninfo_len - sizeof(*tuninfo))) 371 return -EINVAL; 372 373 newts = lwtunnel_state_alloc(tuninfo_len + sizeof(*slwt)); 374 if (!newts) 375 return -ENOMEM; 376 377 slwt = seg6_lwt_lwtunnel(newts); 378 379 err = dst_cache_init(&slwt->cache, GFP_KERNEL); 380 if (err) { 381 kfree(newts); 382 return err; 383 } 384 385 memcpy(&slwt->tuninfo, tuninfo, tuninfo_len); 386 387 newts->type = LWTUNNEL_ENCAP_SEG6; 388 newts->flags |= LWTUNNEL_STATE_OUTPUT_REDIRECT | 389 LWTUNNEL_STATE_INPUT_REDIRECT; 390 newts->headroom = seg6_lwt_headroom(tuninfo); 391 392 *ts = newts; 393 394 return 0; 395 } 396 397 static void seg6_destroy_state(struct lwtunnel_state *lwt) 398 { 399 dst_cache_destroy(&seg6_lwt_lwtunnel(lwt)->cache); 400 } 401 402 static int seg6_fill_encap_info(struct sk_buff *skb, 403 struct lwtunnel_state *lwtstate) 404 { 405 struct seg6_iptunnel_encap *tuninfo = seg6_encap_lwtunnel(lwtstate); 406 407 if (nla_put_srh(skb, SEG6_IPTUNNEL_SRH, tuninfo)) 408 return -EMSGSIZE; 409 410 return 0; 411 } 412 413 static int seg6_encap_nlsize(struct lwtunnel_state *lwtstate) 414 { 415 struct seg6_iptunnel_encap *tuninfo = seg6_encap_lwtunnel(lwtstate); 416 417 return nla_total_size(SEG6_IPTUN_ENCAP_SIZE(tuninfo)); 418 } 419 420 static int seg6_encap_cmp(struct lwtunnel_state *a, struct lwtunnel_state *b) 421 { 422 struct seg6_iptunnel_encap *a_hdr = seg6_encap_lwtunnel(a); 423 struct seg6_iptunnel_encap *b_hdr = seg6_encap_lwtunnel(b); 424 int len = SEG6_IPTUN_ENCAP_SIZE(a_hdr); 425 426 if (len != SEG6_IPTUN_ENCAP_SIZE(b_hdr)) 427 return 1; 428 429 return memcmp(a_hdr, b_hdr, len); 430 } 431 432 static const struct lwtunnel_encap_ops seg6_iptun_ops = { 433 .build_state = seg6_build_state, 434 .destroy_state = seg6_destroy_state, 435 .output = seg6_output, 436 .input = seg6_input, 437 .fill_encap = seg6_fill_encap_info, 438 .get_encap_size = seg6_encap_nlsize, 439 .cmp_encap = seg6_encap_cmp, 440 .owner = THIS_MODULE, 441 }; 442 443 int __init seg6_iptunnel_init(void) 444 { 445 return lwtunnel_encap_add_ops(&seg6_iptun_ops, LWTUNNEL_ENCAP_SEG6); 446 } 447 448 void seg6_iptunnel_exit(void) 449 { 450 lwtunnel_encap_del_ops(&seg6_iptun_ops, LWTUNNEL_ENCAP_SEG6); 451 } 452