net/ipv6/seg6_iptunnel.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  *  SR-IPv6 implementation
   4  *
   5  *  Author:
   6  *  David Lebrun <david.lebrun@uclouvain.be>
   7  */
   8
   9 #include <linux/types.h>
  10 #include <linux/skbuff.h>
  11 #include <linux/net.h>
  12 #include <linux/module.h>
  13 #include <net/ip.h>
  14 #include <net/ip_tunnels.h>
  15 #include <net/lwtunnel.h>
  16 #include <net/netevent.h>
  17 #include <net/netns/generic.h>
  18 #include <net/ip6_fib.h>
  19 #include <net/route.h>
  20 #include <net/seg6.h>
  21 #include <linux/seg6.h>
  22 #include <linux/seg6_iptunnel.h>
  23 #include <net/addrconf.h>
  24 #include <net/ip6_route.h>
  25 #include <net/dst_cache.h>
  26 #ifdef CONFIG_IPV6_SEG6_HMAC
  27 #include <net/seg6_hmac.h>
  28 #endif
  29 #include <linux/netfilter.h>
  30
  31 static size_t seg6_lwt_headroom(struct seg6_iptunnel_encap *tuninfo)
  32 {
  33         int head = 0;
  34
  35         switch (tuninfo->mode) {
  36         case SEG6_IPTUN_MODE_INLINE:
  37                 break;
  38         case SEG6_IPTUN_MODE_ENCAP:
  39         case SEG6_IPTUN_MODE_ENCAP_RED:
  40                 head = sizeof(struct ipv6hdr);
  41                 break;
  42         case SEG6_IPTUN_MODE_L2ENCAP:
  43         case SEG6_IPTUN_MODE_L2ENCAP_RED:
  44                 return 0;
  45         }
  46
  47         return ((tuninfo->srh->hdrlen + 1) << 3) + head;
  48 }
  49
  50 struct seg6_lwt {
  51         struct dst_cache cache;
  52         struct seg6_iptunnel_encap tuninfo[];
  53 };
  54
  55 static inline struct seg6_lwt *seg6_lwt_lwtunnel(struct lwtunnel_state *lwt)
  56 {
  57         return (struct seg6_lwt *)lwt->data;
  58 }
  59
  60 static inline struct seg6_iptunnel_encap *
  61 seg6_encap_lwtunnel(struct lwtunnel_state *lwt)
  62 {
  63         return seg6_lwt_lwtunnel(lwt)->tuninfo;
  64 }
  65
  66 static const struct nla_policy seg6_iptunnel_policy[SEG6_IPTUNNEL_MAX + 1] = {
  67         [SEG6_IPTUNNEL_SRH]     = { .type = NLA_BINARY },
  68 };
  69
  70 static int nla_put_srh(struct sk_buff *skb, int attrtype,
  71                        struct seg6_iptunnel_encap *tuninfo)
  72 {
  73         struct seg6_iptunnel_encap *data;
  74         struct nlattr *nla;
  75         int len;
  76
  77         len = SEG6_IPTUN_ENCAP_SIZE(tuninfo);
  78
  79         nla = nla_reserve(skb, attrtype, len);
  80         if (!nla)
  81                 return -EMSGSIZE;
  82
  83         data = nla_data(nla);
  84         memcpy(data, tuninfo, len);
  85
  86         return 0;
  87 }
  88
  89 static void set_tun_src(struct net *net, struct net_device *dev,
  90                         struct in6_addr *daddr, struct in6_addr *saddr)
  91 {
  92         struct seg6_pernet_data *sdata = seg6_pernet(net);
  93         struct in6_addr *tun_src;
  94
  95         rcu_read_lock();
  96
  97         tun_src = rcu_dereference(sdata->tun_src);
  98
  99         if (!ipv6_addr_any(tun_src)) {
 100                 memcpy(saddr, tun_src, sizeof(struct in6_addr));
 101         } else {
 102                 ipv6_dev_get_saddr(net, dev, daddr, IPV6_PREFER_SRC_PUBLIC,
 103                                    saddr);
 104         }
 105
 106         rcu_read_unlock();
 107 }
 108
 109 /* Compute flowlabel for outer IPv6 header */
 110 static __be32 seg6_make_flowlabel(struct net *net, struct sk_buff *skb,
 111                                   struct ipv6hdr *inner_hdr)
 112 {
 113         int do_flowlabel = net->ipv6.sysctl.seg6_flowlabel;
 114         __be32 flowlabel = 0;
 115         u32 hash;
 116
 117         if (do_flowlabel > 0) {
 118                 hash = skb_get_hash(skb);
 119                 hash = rol32(hash, 16);
 120                 flowlabel = (__force __be32)hash & IPV6_FLOWLABEL_MASK;
 121         } else if (!do_flowlabel && skb->protocol == htons(ETH_P_IPV6)) {
 122                 flowlabel = ip6_flowlabel(inner_hdr);
 123         }
 124         return flowlabel;
 125 }
 126
 127 static int __seg6_do_srh_encap(struct sk_buff *skb, struct ipv6_sr_hdr *osrh,
 128                                int proto, struct dst_entry *cache_dst)
 129 {
 130         struct dst_entry *dst = skb_dst(skb);
 131         struct net *net = dev_net(dst->dev);
 132         struct ipv6hdr *hdr, *inner_hdr;
 133         struct ipv6_sr_hdr *isrh;
 134         int hdrlen, tot_len, err;
 135         __be32 flowlabel;
 136
 137         hdrlen = (osrh->hdrlen + 1) << 3;
 138         tot_len = hdrlen + sizeof(*hdr);
 139
 140         err = skb_cow_head(skb, tot_len + dst_dev_overhead(cache_dst, skb));
 141         if (unlikely(err))
 142                 return err;
 143
 144         inner_hdr = ipv6_hdr(skb);
 145         flowlabel = seg6_make_flowlabel(net, skb, inner_hdr);
 146
 147         skb_push(skb, tot_len);
 148         skb_reset_network_header(skb);
 149         skb_mac_header_rebuild(skb);
 150         hdr = ipv6_hdr(skb);
 151
 152         /* inherit tc, flowlabel and hlim
 153          * hlim will be decremented in ip6_forward() afterwards and
 154          * decapsulation will overwrite inner hlim with outer hlim
 155          */
 156
 157         if (skb->protocol == htons(ETH_P_IPV6)) {
 158                 ip6_flow_hdr(hdr, ip6_tclass(ip6_flowinfo(inner_hdr)),
 159                              flowlabel);
 160                 hdr->hop_limit = inner_hdr->hop_limit;
 161         } else {
 162                 ip6_flow_hdr(hdr, 0, flowlabel);
 163                 hdr->hop_limit = ip6_dst_hoplimit(skb_dst(skb));
 164
 165                 memset(IP6CB(skb), 0, sizeof(*IP6CB(skb)));
 166
 167                 /* the control block has been erased, so we have to set the
 168                  * iif once again.
 169                  * We read the receiving interface index directly from the
 170                  * skb->skb_iif as it is done in the IPv4 receiving path (i.e.:
 171                  * ip_rcv_core(...)).
 172                  */
 173                 IP6CB(skb)->iif = skb->skb_iif;
 174         }
 175
 176         hdr->nexthdr = NEXTHDR_ROUTING;
 177
 178         isrh = (void *)hdr + sizeof(*hdr);
 179         memcpy(isrh, osrh, hdrlen);
 180
 181         isrh->nexthdr = proto;
 182
 183         hdr->daddr = isrh->segments[isrh->first_segment];
 184         set_tun_src(net, dst->dev, &hdr->daddr, &hdr->saddr);
 185
 186 #ifdef CONFIG_IPV6_SEG6_HMAC
 187         if (sr_has_hmac(isrh)) {
 188                 err = seg6_push_hmac(net, &hdr->saddr, isrh);
 189                 if (unlikely(err))
 190                         return err;
 191         }
 192 #endif
 193
 194         hdr->payload_len = htons(skb->len - sizeof(struct ipv6hdr));
 195
 196         skb_postpush_rcsum(skb, hdr, tot_len);
 197
 198         return 0;
 199 }
 200
 201 /* encapsulate an IPv6 packet within an outer IPv6 header with a given SRH */
 202 int seg6_do_srh_encap(struct sk_buff *skb, struct ipv6_sr_hdr *osrh, int proto)
 203 {
 204         return __seg6_do_srh_encap(skb, osrh, proto, NULL);
 205 }
 206 EXPORT_SYMBOL_GPL(seg6_do_srh_encap);
 207
 208 /* encapsulate an IPv6 packet within an outer IPv6 header with reduced SRH */
 209 static int seg6_do_srh_encap_red(struct sk_buff *skb,
 210                                  struct ipv6_sr_hdr *osrh, int proto,
 211                                  struct dst_entry *cache_dst)
 212 {
 213         __u8 first_seg = osrh->first_segment;
 214         struct dst_entry *dst = skb_dst(skb);
 215         struct net *net = dev_net(dst->dev);
 216         struct ipv6hdr *hdr, *inner_hdr;
 217         int hdrlen = ipv6_optlen(osrh);
 218         int red_tlv_offset, tlv_offset;
 219         struct ipv6_sr_hdr *isrh;
 220         bool skip_srh = false;
 221         __be32 flowlabel;
 222         int tot_len, err;
 223         int red_hdrlen;
 224         int tlvs_len;
 225
 226         if (first_seg > 0) {
 227                 red_hdrlen = hdrlen - sizeof(struct in6_addr);
 228         } else {
 229                 /* NOTE: if tag/flags and/or other TLVs are introduced in the
 230                  * seg6_iptunnel infrastructure, they should be considered when
 231                  * deciding to skip the SRH.
 232                  */
 233                 skip_srh = !sr_has_hmac(osrh);
 234
 235                 red_hdrlen = skip_srh ? 0 : hdrlen;
 236         }
 237
 238         tot_len = red_hdrlen + sizeof(struct ipv6hdr);
 239
 240         err = skb_cow_head(skb, tot_len + dst_dev_overhead(cache_dst, skb));
 241         if (unlikely(err))
 242                 return err;
 243
 244         inner_hdr = ipv6_hdr(skb);
 245         flowlabel = seg6_make_flowlabel(net, skb, inner_hdr);
 246
 247         skb_push(skb, tot_len);
 248         skb_reset_network_header(skb);
 249         skb_mac_header_rebuild(skb);
 250         hdr = ipv6_hdr(skb);
 251
 252         /* based on seg6_do_srh_encap() */
 253         if (skb->protocol == htons(ETH_P_IPV6)) {
 254                 ip6_flow_hdr(hdr, ip6_tclass(ip6_flowinfo(inner_hdr)),
 255                              flowlabel);
 256                 hdr->hop_limit = inner_hdr->hop_limit;
 257         } else {
 258                 ip6_flow_hdr(hdr, 0, flowlabel);
 259                 hdr->hop_limit = ip6_dst_hoplimit(skb_dst(skb));
 260
 261                 memset(IP6CB(skb), 0, sizeof(*IP6CB(skb)));
 262                 IP6CB(skb)->iif = skb->skb_iif;
 263         }
 264
 265         /* no matter if we have to skip the SRH or not, the first segment
 266          * always comes in the pushed IPv6 header.
 267          */
 268         hdr->daddr = osrh->segments[first_seg];
 269
 270         if (skip_srh) {
 271                 hdr->nexthdr = proto;
 272
 273                 set_tun_src(net, dst->dev, &hdr->daddr, &hdr->saddr);
 274                 goto out;
 275         }
 276
 277         /* we cannot skip the SRH, slow path */
 278
 279         hdr->nexthdr = NEXTHDR_ROUTING;
 280         isrh = (void *)hdr + sizeof(struct ipv6hdr);
 281
 282         if (unlikely(!first_seg)) {
 283                 /* this is a very rare case; we have only one SID but
 284                  * we cannot skip the SRH since we are carrying some
 285                  * other info.
 286                  */
 287                 memcpy(isrh, osrh, hdrlen);
 288                 goto srcaddr;
 289         }
 290
 291         tlv_offset = sizeof(*osrh) + (first_seg + 1) * sizeof(struct in6_addr);
 292         red_tlv_offset = tlv_offset - sizeof(struct in6_addr);
 293
 294         memcpy(isrh, osrh, red_tlv_offset);
 295
 296         tlvs_len = hdrlen - tlv_offset;
 297         if (unlikely(tlvs_len > 0)) {
 298                 const void *s = (const void *)osrh + tlv_offset;
 299                 void *d = (void *)isrh + red_tlv_offset;
 300
 301                 memcpy(d, s, tlvs_len);
 302         }
 303
 304         --isrh->first_segment;
 305         isrh->hdrlen -= 2;
 306
 307 srcaddr:
 308         isrh->nexthdr = proto;
 309         set_tun_src(net, dst->dev, &hdr->daddr, &hdr->saddr);
 310
 311 #ifdef CONFIG_IPV6_SEG6_HMAC
 312         if (unlikely(!skip_srh && sr_has_hmac(isrh))) {
 313                 err = seg6_push_hmac(net, &hdr->saddr, isrh);
 314                 if (unlikely(err))
 315                         return err;
 316         }
 317 #endif
 318
 319 out:
 320         hdr->payload_len = htons(skb->len - sizeof(struct ipv6hdr));
 321
 322         skb_postpush_rcsum(skb, hdr, tot_len);
 323
 324         return 0;
 325 }
 326
 327 static int __seg6_do_srh_inline(struct sk_buff *skb, struct ipv6_sr_hdr *osrh,
 328                                 struct dst_entry *cache_dst)
 329 {
 330         struct ipv6hdr *hdr, *oldhdr;
 331         struct ipv6_sr_hdr *isrh;
 332         int hdrlen, err;
 333
 334         hdrlen = (osrh->hdrlen + 1) << 3;
 335
 336         err = skb_cow_head(skb, hdrlen + dst_dev_overhead(cache_dst, skb));
 337         if (unlikely(err))
 338                 return err;
 339
 340         oldhdr = ipv6_hdr(skb);
 341
 342         skb_pull(skb, sizeof(struct ipv6hdr));
 343         skb_postpull_rcsum(skb, skb_network_header(skb),
 344                            sizeof(struct ipv6hdr));
 345
 346         skb_push(skb, sizeof(struct ipv6hdr) + hdrlen);
 347         skb_reset_network_header(skb);
 348         skb_mac_header_rebuild(skb);
 349
 350         hdr = ipv6_hdr(skb);
 351
 352         memmove(hdr, oldhdr, sizeof(*hdr));
 353
 354         isrh = (void *)hdr + sizeof(*hdr);
 355         memcpy(isrh, osrh, hdrlen);
 356
 357         isrh->nexthdr = hdr->nexthdr;
 358         hdr->nexthdr = NEXTHDR_ROUTING;
 359
 360         isrh->segments[0] = hdr->daddr;
 361         hdr->daddr = isrh->segments[isrh->first_segment];
 362
 363 #ifdef CONFIG_IPV6_SEG6_HMAC
 364         if (sr_has_hmac(isrh)) {
 365                 struct net *net = dev_net(skb_dst(skb)->dev);
 366
 367                 err = seg6_push_hmac(net, &hdr->saddr, isrh);
 368                 if (unlikely(err))
 369                         return err;
 370         }
 371 #endif
 372
 373         hdr->payload_len = htons(skb->len - sizeof(struct ipv6hdr));
 374
 375         skb_postpush_rcsum(skb, hdr, sizeof(struct ipv6hdr) + hdrlen);
 376
 377         return 0;
 378 }
 379
 380 static int seg6_do_srh(struct sk_buff *skb, struct dst_entry *cache_dst)
 381 {
 382         struct dst_entry *dst = skb_dst(skb);
 383         struct seg6_iptunnel_encap *tinfo;
 384         int proto, err = 0;
 385
 386         tinfo = seg6_encap_lwtunnel(dst->lwtstate);
 387
 388         switch (tinfo->mode) {
 389         case SEG6_IPTUN_MODE_INLINE:
 390                 if (skb->protocol != htons(ETH_P_IPV6))
 391                         return -EINVAL;
 392
 393                 err = __seg6_do_srh_inline(skb, tinfo->srh, cache_dst);
 394                 if (err)
 395                         return err;
 396                 break;
 397         case SEG6_IPTUN_MODE_ENCAP:
 398         case SEG6_IPTUN_MODE_ENCAP_RED:
 399                 err = iptunnel_handle_offloads(skb, SKB_GSO_IPXIP6);
 400                 if (err)
 401                         return err;
 402
 403                 if (skb->protocol == htons(ETH_P_IPV6))
 404                         proto = IPPROTO_IPV6;
 405                 else if (skb->protocol == htons(ETH_P_IP))
 406                         proto = IPPROTO_IPIP;
 407                 else
 408                         return -EINVAL;
 409
 410                 if (tinfo->mode == SEG6_IPTUN_MODE_ENCAP)
 411                         err = __seg6_do_srh_encap(skb, tinfo->srh,
 412                                                   proto, cache_dst);
 413                 else
 414                         err = seg6_do_srh_encap_red(skb, tinfo->srh,
 415                                                     proto, cache_dst);
 416
 417                 if (err)
 418                         return err;
 419
 420                 skb_set_inner_transport_header(skb, skb_transport_offset(skb));
 421                 skb_set_inner_protocol(skb, skb->protocol);
 422                 skb->protocol = htons(ETH_P_IPV6);
 423                 break;
 424         case SEG6_IPTUN_MODE_L2ENCAP:
 425         case SEG6_IPTUN_MODE_L2ENCAP_RED:
 426                 if (!skb_mac_header_was_set(skb))
 427                         return -EINVAL;
 428
 429                 if (pskb_expand_head(skb, skb->mac_len, 0, GFP_ATOMIC) < 0)
 430                         return -ENOMEM;
 431
 432                 skb_mac_header_rebuild(skb);
 433                 skb_push(skb, skb->mac_len);
 434
 435                 if (tinfo->mode == SEG6_IPTUN_MODE_L2ENCAP)
 436                         err = __seg6_do_srh_encap(skb, tinfo->srh,
 437                                                   IPPROTO_ETHERNET,
 438                                                   cache_dst);
 439                 else
 440                         err = seg6_do_srh_encap_red(skb, tinfo->srh,
 441                                                     IPPROTO_ETHERNET,
 442                                                     cache_dst);
 443
 444                 if (err)
 445                         return err;
 446
 447                 skb->protocol = htons(ETH_P_IPV6);
 448                 break;
 449         }
 450
 451         skb_set_transport_header(skb, sizeof(struct ipv6hdr));
 452         nf_reset_ct(skb);
 453
 454         return 0;
 455 }
 456
 457 /* insert an SRH within an IPv6 packet, just after the IPv6 header */
 458 int seg6_do_srh_inline(struct sk_buff *skb, struct ipv6_sr_hdr *osrh)
 459 {
 460         return __seg6_do_srh_inline(skb, osrh, NULL);
 461 }
 462 EXPORT_SYMBOL_GPL(seg6_do_srh_inline);
 463
 464 static int seg6_input_finish(struct net *net, struct sock *sk,
 465                              struct sk_buff *skb)
 466 {
 467         return dst_input(skb);
 468 }
 469
 470 static int seg6_input_core(struct net *net, struct sock *sk,
 471                            struct sk_buff *skb)
 472 {
 473         struct dst_entry *orig_dst = skb_dst(skb);
 474         struct dst_entry *dst = NULL;
 475         struct seg6_lwt *slwt;
 476         int err;
 477
 478         slwt = seg6_lwt_lwtunnel(orig_dst->lwtstate);
 479
 480         local_bh_disable();
 481         dst = dst_cache_get(&slwt->cache);
 482         local_bh_enable();
 483
 484         err = seg6_do_srh(skb, dst);
 485         if (unlikely(err))
 486                 goto drop;
 487
 488         if (!dst) {
 489                 ip6_route_input(skb);
 490                 dst = skb_dst(skb);
 491                 if (!dst->error) {
 492                         local_bh_disable();
 493                         dst_cache_set_ip6(&slwt->cache, dst,
 494                                           &ipv6_hdr(skb)->saddr);
 495                         local_bh_enable();
 496                 }
 497
 498                 err = skb_cow_head(skb, LL_RESERVED_SPACE(dst->dev));
 499                 if (unlikely(err))
 500                         goto drop;
 501         } else {
 502                 skb_dst_drop(skb);
 503                 skb_dst_set(skb, dst);
 504         }
 505
 506         if (static_branch_unlikely(&nf_hooks_lwtunnel_enabled))
 507                 return NF_HOOK(NFPROTO_IPV6, NF_INET_LOCAL_OUT,
 508                                dev_net(skb->dev), NULL, skb, NULL,
 509                                skb_dst(skb)->dev, seg6_input_finish);
 510
 511         return seg6_input_finish(dev_net(skb->dev), NULL, skb);
 512 drop:
 513         kfree_skb(skb);
 514         return err;
 515 }
 516
 517 static int seg6_input_nf(struct sk_buff *skb)
 518 {
 519         struct net_device *dev = skb_dst(skb)->dev;
 520         struct net *net = dev_net(skb->dev);
 521
 522         switch (skb->protocol) {
 523         case htons(ETH_P_IP):
 524                 return NF_HOOK(NFPROTO_IPV4, NF_INET_POST_ROUTING, net, NULL,
 525                                skb, NULL, dev, seg6_input_core);
 526         case htons(ETH_P_IPV6):
 527                 return NF_HOOK(NFPROTO_IPV6, NF_INET_POST_ROUTING, net, NULL,
 528                                skb, NULL, dev, seg6_input_core);
 529         }
 530
 531         return -EINVAL;
 532 }
 533
 534 static int seg6_input(struct sk_buff *skb)
 535 {
 536         if (static_branch_unlikely(&nf_hooks_lwtunnel_enabled))
 537                 return seg6_input_nf(skb);
 538
 539         return seg6_input_core(dev_net(skb->dev), NULL, skb);
 540 }
 541
 542 static int seg6_output_core(struct net *net, struct sock *sk,
 543                             struct sk_buff *skb)
 544 {
 545         struct dst_entry *orig_dst = skb_dst(skb);
 546         struct dst_entry *dst = NULL;
 547         struct seg6_lwt *slwt;
 548         int err;
 549
 550         slwt = seg6_lwt_lwtunnel(orig_dst->lwtstate);
 551
 552         local_bh_disable();
 553         dst = dst_cache_get(&slwt->cache);
 554         local_bh_enable();
 555
 556         err = seg6_do_srh(skb, dst);
 557         if (unlikely(err))
 558                 goto drop;
 559
 560         if (unlikely(!dst)) {
 561                 struct ipv6hdr *hdr = ipv6_hdr(skb);
 562                 struct flowi6 fl6;
 563
 564                 memset(&fl6, 0, sizeof(fl6));
 565                 fl6.daddr = hdr->daddr;
 566                 fl6.saddr = hdr->saddr;
 567                 fl6.flowlabel = ip6_flowinfo(hdr);
 568                 fl6.flowi6_mark = skb->mark;
 569                 fl6.flowi6_proto = hdr->nexthdr;
 570
 571                 dst = ip6_route_output(net, NULL, &fl6);
 572                 if (dst->error) {
 573                         err = dst->error;
 574                         dst_release(dst);
 575                         goto drop;
 576                 }
 577
 578                 local_bh_disable();
 579                 dst_cache_set_ip6(&slwt->cache, dst, &fl6.saddr);
 580                 local_bh_enable();
 581
 582                 err = skb_cow_head(skb, LL_RESERVED_SPACE(dst->dev));
 583                 if (unlikely(err))
 584                         goto drop;
 585         }
 586
 587         skb_dst_drop(skb);
 588         skb_dst_set(skb, dst);
 589
 590         if (static_branch_unlikely(&nf_hooks_lwtunnel_enabled))
 591                 return NF_HOOK(NFPROTO_IPV6, NF_INET_LOCAL_OUT, net, sk, skb,
 592                                NULL, skb_dst(skb)->dev, dst_output);
 593
 594         return dst_output(net, sk, skb);
 595 drop:
 596         kfree_skb(skb);
 597         return err;
 598 }
 599
 600 static int seg6_output_nf(struct net *net, struct sock *sk, struct sk_buff *skb)
 601 {
 602         struct net_device *dev = skb_dst(skb)->dev;
 603
 604         switch (skb->protocol) {
 605         case htons(ETH_P_IP):
 606                 return NF_HOOK(NFPROTO_IPV4, NF_INET_POST_ROUTING, net, sk, skb,
 607                                NULL, dev, seg6_output_core);
 608         case htons(ETH_P_IPV6):
 609                 return NF_HOOK(NFPROTO_IPV6, NF_INET_POST_ROUTING, net, sk, skb,
 610                                NULL, dev, seg6_output_core);
 611         }
 612
 613         return -EINVAL;
 614 }
 615
 616 static int seg6_output(struct net *net, struct sock *sk, struct sk_buff *skb)
 617 {
 618         if (static_branch_unlikely(&nf_hooks_lwtunnel_enabled))
 619                 return seg6_output_nf(net, sk, skb);
 620
 621         return seg6_output_core(net, sk, skb);
 622 }
 623
 624 static int seg6_build_state(struct net *net, struct nlattr *nla,
 625                             unsigned int family, const void *cfg,
 626                             struct lwtunnel_state **ts,
 627                             struct netlink_ext_ack *extack)
 628 {
 629         struct nlattr *tb[SEG6_IPTUNNEL_MAX + 1];
 630         struct seg6_iptunnel_encap *tuninfo;
 631         struct lwtunnel_state *newts;
 632         int tuninfo_len, min_size;
 633         struct seg6_lwt *slwt;
 634         int err;
 635
 636         if (family != AF_INET && family != AF_INET6)
 637                 return -EINVAL;
 638
 639         err = nla_parse_nested_deprecated(tb, SEG6_IPTUNNEL_MAX, nla,
 640                                           seg6_iptunnel_policy, extack);
 641
 642         if (err < 0)
 643                 return err;
 644
 645         if (!tb[SEG6_IPTUNNEL_SRH])
 646                 return -EINVAL;
 647
 648         tuninfo = nla_data(tb[SEG6_IPTUNNEL_SRH]);
 649         tuninfo_len = nla_len(tb[SEG6_IPTUNNEL_SRH]);
 650
 651         /* tuninfo must contain at least the iptunnel encap structure,
 652          * the SRH and one segment
 653          */
 654         min_size = sizeof(*tuninfo) + sizeof(struct ipv6_sr_hdr) +
 655                    sizeof(struct in6_addr);
 656         if (tuninfo_len < min_size)
 657                 return -EINVAL;
 658
 659         switch (tuninfo->mode) {
 660         case SEG6_IPTUN_MODE_INLINE:
 661                 if (family != AF_INET6)
 662                         return -EINVAL;
 663
 664                 break;
 665         case SEG6_IPTUN_MODE_ENCAP:
 666                 break;
 667         case SEG6_IPTUN_MODE_L2ENCAP:
 668                 break;
 669         case SEG6_IPTUN_MODE_ENCAP_RED:
 670                 break;
 671         case SEG6_IPTUN_MODE_L2ENCAP_RED:
 672                 break;
 673         default:
 674                 return -EINVAL;
 675         }
 676
 677         /* verify that SRH is consistent */
 678         if (!seg6_validate_srh(tuninfo->srh, tuninfo_len - sizeof(*tuninfo), false))
 679                 return -EINVAL;
 680
 681         newts = lwtunnel_state_alloc(tuninfo_len + sizeof(*slwt));
 682         if (!newts)
 683                 return -ENOMEM;
 684
 685         slwt = seg6_lwt_lwtunnel(newts);
 686
 687         err = dst_cache_init(&slwt->cache, GFP_ATOMIC);
 688         if (err) {
 689                 kfree(newts);
 690                 return err;
 691         }
 692
 693         memcpy(&slwt->tuninfo, tuninfo, tuninfo_len);
 694
 695         newts->type = LWTUNNEL_ENCAP_SEG6;
 696         newts->flags |= LWTUNNEL_STATE_INPUT_REDIRECT;
 697
 698         if (tuninfo->mode != SEG6_IPTUN_MODE_L2ENCAP)
 699                 newts->flags |= LWTUNNEL_STATE_OUTPUT_REDIRECT;
 700
 701         newts->headroom = seg6_lwt_headroom(tuninfo);
 702
 703         *ts = newts;
 704
 705         return 0;
 706 }
 707
 708 static void seg6_destroy_state(struct lwtunnel_state *lwt)
 709 {
 710         dst_cache_destroy(&seg6_lwt_lwtunnel(lwt)->cache);
 711 }
 712
 713 static int seg6_fill_encap_info(struct sk_buff *skb,
 714                                 struct lwtunnel_state *lwtstate)
 715 {
 716         struct seg6_iptunnel_encap *tuninfo = seg6_encap_lwtunnel(lwtstate);
 717
 718         if (nla_put_srh(skb, SEG6_IPTUNNEL_SRH, tuninfo))
 719                 return -EMSGSIZE;
 720
 721         return 0;
 722 }
 723
 724 static int seg6_encap_nlsize(struct lwtunnel_state *lwtstate)
 725 {
 726         struct seg6_iptunnel_encap *tuninfo = seg6_encap_lwtunnel(lwtstate);
 727
 728         return nla_total_size(SEG6_IPTUN_ENCAP_SIZE(tuninfo));
 729 }
 730
 731 static int seg6_encap_cmp(struct lwtunnel_state *a, struct lwtunnel_state *b)
 732 {
 733         struct seg6_iptunnel_encap *a_hdr = seg6_encap_lwtunnel(a);
 734         struct seg6_iptunnel_encap *b_hdr = seg6_encap_lwtunnel(b);
 735         int len = SEG6_IPTUN_ENCAP_SIZE(a_hdr);
 736
 737         if (len != SEG6_IPTUN_ENCAP_SIZE(b_hdr))
 738                 return 1;
 739
 740         return memcmp(a_hdr, b_hdr, len);
 741 }
 742
 743 static const struct lwtunnel_encap_ops seg6_iptun_ops = {
 744         .build_state = seg6_build_state,
 745         .destroy_state = seg6_destroy_state,
 746         .output = seg6_output,
 747         .input = seg6_input,
 748         .fill_encap = seg6_fill_encap_info,
 749         .get_encap_size = seg6_encap_nlsize,
 750         .cmp_encap = seg6_encap_cmp,
 751         .owner = THIS_MODULE,
 752 };
 753
 754 int __init seg6_iptunnel_init(void)
 755 {
 756         return lwtunnel_encap_add_ops(&seg6_iptun_ops, LWTUNNEL_ENCAP_SEG6);
 757 }
 758
 759 void seg6_iptunnel_exit(void)
 760 {
 761         lwtunnel_encap_del_ops(&seg6_iptun_ops, LWTUNNEL_ENCAP_SEG6);
 762 }