net/ipv6/seg6.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/errno.h>
  10 #include <linux/types.h>
  11 #include <linux/socket.h>
  12 #include <linux/net.h>
  13 #include <linux/in6.h>
  14 #include <linux/slab.h>
  15 #include <linux/rhashtable.h>
  16
  17 #include <net/ipv6.h>
  18 #include <net/protocol.h>
  19
  20 #include <net/seg6.h>
  21 #include <net/genetlink.h>
  22 #include <linux/seg6.h>
  23 #include <linux/seg6_genl.h>
  24 #ifdef CONFIG_IPV6_SEG6_HMAC
  25 #include <net/seg6_hmac.h>
  26 #endif
  27
  28 bool seg6_validate_srh(struct ipv6_sr_hdr *srh, int len, bool reduced)
  29 {
  30         unsigned int tlv_offset;
  31         int max_last_entry;
  32         int trailing;
  33
  34         if (srh->type != IPV6_SRCRT_TYPE_4)
  35                 return false;
  36
  37         if (((srh->hdrlen + 1) << 3) != len)
  38                 return false;
  39
  40         if (!reduced && srh->segments_left > srh->first_segment) {
  41                 return false;
  42         } else {
  43                 max_last_entry = (srh->hdrlen / 2) - 1;
  44
  45                 if (srh->first_segment > max_last_entry)
  46                         return false;
  47
  48                 if (srh->segments_left > srh->first_segment + 1)
  49                         return false;
  50         }
  51
  52         tlv_offset = sizeof(*srh) + ((srh->first_segment + 1) << 4);
  53
  54         trailing = len - tlv_offset;
  55         if (trailing < 0)
  56                 return false;
  57
  58         while (trailing) {
  59                 struct sr6_tlv *tlv;
  60                 unsigned int tlv_len;
  61
  62                 if (trailing < sizeof(*tlv))
  63                         return false;
  64
  65                 tlv = (struct sr6_tlv *)((unsigned char *)srh + tlv_offset);
  66                 tlv_len = sizeof(*tlv) + tlv->len;
  67
  68                 trailing -= tlv_len;
  69                 if (trailing < 0)
  70                         return false;
  71
  72                 tlv_offset += tlv_len;
  73         }
  74
  75         return true;
  76 }
  77
  78 struct ipv6_sr_hdr *seg6_get_srh(struct sk_buff *skb, int flags)
  79 {
  80         struct ipv6_sr_hdr *srh;
  81         int len, srhoff = 0;
  82
  83         if (ipv6_find_hdr(skb, &srhoff, IPPROTO_ROUTING, NULL, &flags) < 0)
  84                 return NULL;
  85
  86         if (!pskb_may_pull(skb, srhoff + sizeof(*srh)))
  87                 return NULL;
  88
  89         srh = (struct ipv6_sr_hdr *)(skb->data + srhoff);
  90
  91         len = (srh->hdrlen + 1) << 3;
  92
  93         if (!pskb_may_pull(skb, srhoff + len))
  94                 return NULL;
  95
  96         /* note that pskb_may_pull may change pointers in header;
  97          * for this reason it is necessary to reload them when needed.
  98          */
  99         srh = (struct ipv6_sr_hdr *)(skb->data + srhoff);
 100
 101         if (!seg6_validate_srh(srh, len, true))
 102                 return NULL;
 103
 104         return srh;
 105 }
 106
 107 /* Determine if an ICMP invoking packet contains a segment routing
 108  * header.  If it does, extract the offset to the true destination
 109  * address, which is in the first segment address.
 110  */
 111 void seg6_icmp_srh(struct sk_buff *skb, struct inet6_skb_parm *opt)
 112 {
 113         __u16 network_header = skb->network_header;
 114         struct ipv6_sr_hdr *srh;
 115
 116         /* Update network header to point to the invoking packet
 117          * inside the ICMP packet, so we can use the seg6_get_srh()
 118          * helper.
 119          */
 120         skb_reset_network_header(skb);
 121
 122         srh = seg6_get_srh(skb, 0);
 123         if (!srh)
 124                 goto out;
 125
 126         if (srh->type != IPV6_SRCRT_TYPE_4)
 127                 goto out;
 128
 129         opt->flags |= IP6SKB_SEG6;
 130         opt->srhoff = (unsigned char *)srh - skb->data;
 131
 132 out:
 133         /* Restore the network header back to the ICMP packet */
 134         skb->network_header = network_header;
 135 }
 136
 137 static struct genl_family seg6_genl_family;
 138
 139 static const struct nla_policy seg6_genl_policy[SEG6_ATTR_MAX + 1] = {
 140         [SEG6_ATTR_DST]                         = { .type = NLA_BINARY,
 141                 .len = sizeof(struct in6_addr) },
 142         [SEG6_ATTR_DSTLEN]                      = { .type = NLA_S32, },
 143         [SEG6_ATTR_HMACKEYID]           = { .type = NLA_U32, },
 144         [SEG6_ATTR_SECRET]                      = { .type = NLA_BINARY, },
 145         [SEG6_ATTR_SECRETLEN]           = { .type = NLA_U8, },
 146         [SEG6_ATTR_ALGID]                       = { .type = NLA_U8, },
 147         [SEG6_ATTR_HMACINFO]            = { .type = NLA_NESTED, },
 148 };
 149
 150 #ifdef CONFIG_IPV6_SEG6_HMAC
 151
 152 static int seg6_genl_sethmac(struct sk_buff *skb, struct genl_info *info)
 153 {
 154         struct net *net = genl_info_net(info);
 155         struct seg6_pernet_data *sdata;
 156         struct seg6_hmac_info *hinfo;
 157         u32 hmackeyid;
 158         char *secret;
 159         int err = 0;
 160         u8 algid;
 161         u8 slen;
 162
 163         sdata = seg6_pernet(net);
 164
 165         if (!info->attrs[SEG6_ATTR_HMACKEYID] ||
 166             !info->attrs[SEG6_ATTR_SECRETLEN] ||
 167             !info->attrs[SEG6_ATTR_ALGID])
 168                 return -EINVAL;
 169
 170         hmackeyid = nla_get_u32(info->attrs[SEG6_ATTR_HMACKEYID]);
 171         slen = nla_get_u8(info->attrs[SEG6_ATTR_SECRETLEN]);
 172         algid = nla_get_u8(info->attrs[SEG6_ATTR_ALGID]);
 173
 174         if (hmackeyid == 0)
 175                 return -EINVAL;
 176
 177         if (slen > SEG6_HMAC_SECRET_LEN)
 178                 return -EINVAL;
 179
 180         mutex_lock(&sdata->lock);
 181         hinfo = seg6_hmac_info_lookup(net, hmackeyid);
 182
 183         if (!slen) {
 184                 err = seg6_hmac_info_del(net, hmackeyid);
 185
 186                 goto out_unlock;
 187         }
 188
 189         if (!info->attrs[SEG6_ATTR_SECRET]) {
 190                 err = -EINVAL;
 191                 goto out_unlock;
 192         }
 193
 194         if (slen > nla_len(info->attrs[SEG6_ATTR_SECRET])) {
 195                 err = -EINVAL;
 196                 goto out_unlock;
 197         }
 198
 199         if (hinfo) {
 200                 err = seg6_hmac_info_del(net, hmackeyid);
 201                 if (err)
 202                         goto out_unlock;
 203         }
 204
 205         secret = (char *)nla_data(info->attrs[SEG6_ATTR_SECRET]);
 206
 207         hinfo = kzalloc(sizeof(*hinfo), GFP_KERNEL);
 208         if (!hinfo) {
 209                 err = -ENOMEM;
 210                 goto out_unlock;
 211         }
 212
 213         memcpy(hinfo->secret, secret, slen);
 214         hinfo->slen = slen;
 215         hinfo->alg_id = algid;
 216         hinfo->hmackeyid = hmackeyid;
 217
 218         err = seg6_hmac_info_add(net, hmackeyid, hinfo);
 219         if (err)
 220                 kfree(hinfo);
 221
 222 out_unlock:
 223         mutex_unlock(&sdata->lock);
 224         return err;
 225 }
 226
 227 #else
 228
 229 static int seg6_genl_sethmac(struct sk_buff *skb, struct genl_info *info)
 230 {
 231         return -ENOTSUPP;
 232 }
 233
 234 #endif
 235
 236 static int seg6_genl_set_tunsrc(struct sk_buff *skb, struct genl_info *info)
 237 {
 238         struct net *net = genl_info_net(info);
 239         struct in6_addr *val, *t_old, *t_new;
 240         struct seg6_pernet_data *sdata;
 241
 242         sdata = seg6_pernet(net);
 243
 244         if (!info->attrs[SEG6_ATTR_DST])
 245                 return -EINVAL;
 246
 247         val = nla_data(info->attrs[SEG6_ATTR_DST]);
 248         t_new = kmemdup(val, sizeof(*val), GFP_KERNEL);
 249         if (!t_new)
 250                 return -ENOMEM;
 251
 252         mutex_lock(&sdata->lock);
 253
 254         t_old = sdata->tun_src;
 255         rcu_assign_pointer(sdata->tun_src, t_new);
 256
 257         mutex_unlock(&sdata->lock);
 258
 259         synchronize_net();
 260         kfree(t_old);
 261
 262         return 0;
 263 }
 264
 265 static int seg6_genl_get_tunsrc(struct sk_buff *skb, struct genl_info *info)
 266 {
 267         struct net *net = genl_info_net(info);
 268         struct in6_addr *tun_src;
 269         struct sk_buff *msg;
 270         void *hdr;
 271
 272         msg = genlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
 273         if (!msg)
 274                 return -ENOMEM;
 275
 276         hdr = genlmsg_put(msg, info->snd_portid, info->snd_seq,
 277                           &seg6_genl_family, 0, SEG6_CMD_GET_TUNSRC);
 278         if (!hdr)
 279                 goto free_msg;
 280
 281         rcu_read_lock();
 282         tun_src = rcu_dereference(seg6_pernet(net)->tun_src);
 283
 284         if (nla_put(msg, SEG6_ATTR_DST, sizeof(struct in6_addr), tun_src))
 285                 goto nla_put_failure;
 286
 287         rcu_read_unlock();
 288
 289         genlmsg_end(msg, hdr);
 290         return genlmsg_reply(msg, info);
 291
 292 nla_put_failure:
 293         rcu_read_unlock();
 294 free_msg:
 295         nlmsg_free(msg);
 296         return -ENOMEM;
 297 }
 298
 299 #ifdef CONFIG_IPV6_SEG6_HMAC
 300
 301 static int __seg6_hmac_fill_info(struct seg6_hmac_info *hinfo,
 302                                  struct sk_buff *msg)
 303 {
 304         if (nla_put_u32(msg, SEG6_ATTR_HMACKEYID, hinfo->hmackeyid) ||
 305             nla_put_u8(msg, SEG6_ATTR_SECRETLEN, hinfo->slen) ||
 306             nla_put(msg, SEG6_ATTR_SECRET, hinfo->slen, hinfo->secret) ||
 307             nla_put_u8(msg, SEG6_ATTR_ALGID, hinfo->alg_id))
 308                 return -1;
 309
 310         return 0;
 311 }
 312
 313 static int __seg6_genl_dumphmac_element(struct seg6_hmac_info *hinfo,
 314                                         u32 portid, u32 seq, u32 flags,
 315                                         struct sk_buff *skb, u8 cmd)
 316 {
 317         void *hdr;
 318
 319         hdr = genlmsg_put(skb, portid, seq, &seg6_genl_family, flags, cmd);
 320         if (!hdr)
 321                 return -ENOMEM;
 322
 323         if (__seg6_hmac_fill_info(hinfo, skb) < 0)
 324                 goto nla_put_failure;
 325
 326         genlmsg_end(skb, hdr);
 327         return 0;
 328
 329 nla_put_failure:
 330         genlmsg_cancel(skb, hdr);
 331         return -EMSGSIZE;
 332 }
 333
 334 static int seg6_genl_dumphmac_start(struct netlink_callback *cb)
 335 {
 336         struct net *net = sock_net(cb->skb->sk);
 337         struct seg6_pernet_data *sdata;
 338         struct rhashtable_iter *iter;
 339
 340         sdata = seg6_pernet(net);
 341         iter = (struct rhashtable_iter *)cb->args[0];
 342
 343         if (!iter) {
 344                 iter = kmalloc(sizeof(*iter), GFP_KERNEL);
 345                 if (!iter)
 346                         return -ENOMEM;
 347
 348                 cb->args[0] = (long)iter;
 349         }
 350
 351         rhashtable_walk_enter(&sdata->hmac_infos, iter);
 352
 353         return 0;
 354 }
 355
 356 static int seg6_genl_dumphmac_done(struct netlink_callback *cb)
 357 {
 358         struct rhashtable_iter *iter = (struct rhashtable_iter *)cb->args[0];
 359
 360         rhashtable_walk_exit(iter);
 361
 362         kfree(iter);
 363
 364         return 0;
 365 }
 366
 367 static int seg6_genl_dumphmac(struct sk_buff *skb, struct netlink_callback *cb)
 368 {
 369         struct rhashtable_iter *iter = (struct rhashtable_iter *)cb->args[0];
 370         struct seg6_hmac_info *hinfo;
 371         int ret;
 372
 373         rhashtable_walk_start(iter);
 374
 375         for (;;) {
 376                 hinfo = rhashtable_walk_next(iter);
 377
 378                 if (IS_ERR(hinfo)) {
 379                         if (PTR_ERR(hinfo) == -EAGAIN)
 380                                 continue;
 381                         ret = PTR_ERR(hinfo);
 382                         goto done;
 383                 } else if (!hinfo) {
 384                         break;
 385                 }
 386
 387                 ret = __seg6_genl_dumphmac_element(hinfo,
 388                                                    NETLINK_CB(cb->skb).portid,
 389                                                    cb->nlh->nlmsg_seq,
 390                                                    NLM_F_MULTI,
 391                                                    skb, SEG6_CMD_DUMPHMAC);
 392                 if (ret)
 393                         goto done;
 394         }
 395
 396         ret = skb->len;
 397
 398 done:
 399         rhashtable_walk_stop(iter);
 400         return ret;
 401 }
 402
 403 #else
 404
 405 static int seg6_genl_dumphmac_start(struct netlink_callback *cb)
 406 {
 407         return 0;
 408 }
 409
 410 static int seg6_genl_dumphmac_done(struct netlink_callback *cb)
 411 {
 412         return 0;
 413 }
 414
 415 static int seg6_genl_dumphmac(struct sk_buff *skb, struct netlink_callback *cb)
 416 {
 417         return -ENOTSUPP;
 418 }
 419
 420 #endif
 421
 422 static int __net_init seg6_net_init(struct net *net)
 423 {
 424         struct seg6_pernet_data *sdata;
 425
 426         sdata = kzalloc(sizeof(*sdata), GFP_KERNEL);
 427         if (!sdata)
 428                 return -ENOMEM;
 429
 430         mutex_init(&sdata->lock);
 431
 432         sdata->tun_src = kzalloc(sizeof(*sdata->tun_src), GFP_KERNEL);
 433         if (!sdata->tun_src) {
 434                 kfree(sdata);
 435                 return -ENOMEM;
 436         }
 437
 438         net->ipv6.seg6_data = sdata;
 439
 440 #ifdef CONFIG_IPV6_SEG6_HMAC
 441         if (seg6_hmac_net_init(net)) {
 442                 kfree(rcu_dereference_raw(sdata->tun_src));
 443                 kfree(sdata);
 444                 return -ENOMEM;
 445         }
 446 #endif
 447
 448         return 0;
 449 }
 450
 451 static void __net_exit seg6_net_exit(struct net *net)
 452 {
 453         struct seg6_pernet_data *sdata = seg6_pernet(net);
 454
 455 #ifdef CONFIG_IPV6_SEG6_HMAC
 456         seg6_hmac_net_exit(net);
 457 #endif
 458
 459         kfree(rcu_dereference_raw(sdata->tun_src));
 460         kfree(sdata);
 461 }
 462
 463 static struct pernet_operations ip6_segments_ops = {
 464         .init = seg6_net_init,
 465         .exit = seg6_net_exit,
 466 };
 467
 468 static const struct genl_ops seg6_genl_ops[] = {
 469         {
 470                 .cmd    = SEG6_CMD_SETHMAC,
 471                 .validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
 472                 .doit   = seg6_genl_sethmac,
 473                 .flags  = GENL_ADMIN_PERM,
 474         },
 475         {
 476                 .cmd    = SEG6_CMD_DUMPHMAC,
 477                 .validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
 478                 .start  = seg6_genl_dumphmac_start,
 479                 .dumpit = seg6_genl_dumphmac,
 480                 .done   = seg6_genl_dumphmac_done,
 481                 .flags  = GENL_ADMIN_PERM,
 482         },
 483         {
 484                 .cmd    = SEG6_CMD_SET_TUNSRC,
 485                 .validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
 486                 .doit   = seg6_genl_set_tunsrc,
 487                 .flags  = GENL_ADMIN_PERM,
 488         },
 489         {
 490                 .cmd    = SEG6_CMD_GET_TUNSRC,
 491                 .validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
 492                 .doit   = seg6_genl_get_tunsrc,
 493                 .flags  = GENL_ADMIN_PERM,
 494         },
 495 };
 496
 497 static struct genl_family seg6_genl_family __ro_after_init = {
 498         .hdrsize        = 0,
 499         .name           = SEG6_GENL_NAME,
 500         .version        = SEG6_GENL_VERSION,
 501         .maxattr        = SEG6_ATTR_MAX,
 502         .policy = seg6_genl_policy,
 503         .netnsok        = true,
 504         .parallel_ops   = true,
 505         .ops            = seg6_genl_ops,
 506         .n_ops          = ARRAY_SIZE(seg6_genl_ops),
 507         .resv_start_op  = SEG6_CMD_GET_TUNSRC + 1,
 508         .module         = THIS_MODULE,
 509 };
 510
 511 int __init seg6_init(void)
 512 {
 513         int err;
 514
 515         err = genl_register_family(&seg6_genl_family);
 516         if (err)
 517                 goto out;
 518
 519         err = register_pernet_subsys(&ip6_segments_ops);
 520         if (err)
 521                 goto out_unregister_genl;
 522
 523 #ifdef CONFIG_IPV6_SEG6_LWTUNNEL
 524         err = seg6_iptunnel_init();
 525         if (err)
 526                 goto out_unregister_pernet;
 527
 528         err = seg6_local_init();
 529         if (err)
 530                 goto out_unregister_pernet;
 531 #endif
 532
 533 #ifdef CONFIG_IPV6_SEG6_HMAC
 534         err = seg6_hmac_init();
 535         if (err)
 536                 goto out_unregister_iptun;
 537 #endif
 538
 539         pr_info("Segment Routing with IPv6\n");
 540
 541 out:
 542         return err;
 543 #ifdef CONFIG_IPV6_SEG6_HMAC
 544 out_unregister_iptun:
 545 #ifdef CONFIG_IPV6_SEG6_LWTUNNEL
 546         seg6_local_exit();
 547         seg6_iptunnel_exit();
 548 #endif
 549 #endif
 550 #ifdef CONFIG_IPV6_SEG6_LWTUNNEL
 551 out_unregister_pernet:
 552         unregister_pernet_subsys(&ip6_segments_ops);
 553 #endif
 554 out_unregister_genl:
 555         genl_unregister_family(&seg6_genl_family);
 556         goto out;
 557 }
 558
 559 void seg6_exit(void)
 560 {
 561 #ifdef CONFIG_IPV6_SEG6_HMAC
 562         seg6_hmac_exit();
 563 #endif
 564 #ifdef CONFIG_IPV6_SEG6_LWTUNNEL
 565         seg6_iptunnel_exit();
 566 #endif
 567         unregister_pernet_subsys(&ip6_segments_ops);
 568         genl_unregister_family(&seg6_genl_family);
 569 }