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 (hinfo) {
 195                 err = seg6_hmac_info_del(net, hmackeyid);
 196                 if (err)
 197                         goto out_unlock;
 198         }
 199
 200         secret = (char *)nla_data(info->attrs[SEG6_ATTR_SECRET]);
 201
 202         hinfo = kzalloc(sizeof(*hinfo), GFP_KERNEL);
 203         if (!hinfo) {
 204                 err = -ENOMEM;
 205                 goto out_unlock;
 206         }
 207
 208         memcpy(hinfo->secret, secret, slen);
 209         hinfo->slen = slen;
 210         hinfo->alg_id = algid;
 211         hinfo->hmackeyid = hmackeyid;
 212
 213         err = seg6_hmac_info_add(net, hmackeyid, hinfo);
 214         if (err)
 215                 kfree(hinfo);
 216
 217 out_unlock:
 218         mutex_unlock(&sdata->lock);
 219         return err;
 220 }
 221
 222 #else
 223
 224 static int seg6_genl_sethmac(struct sk_buff *skb, struct genl_info *info)
 225 {
 226         return -ENOTSUPP;
 227 }
 228
 229 #endif
 230
 231 static int seg6_genl_set_tunsrc(struct sk_buff *skb, struct genl_info *info)
 232 {
 233         struct net *net = genl_info_net(info);
 234         struct in6_addr *val, *t_old, *t_new;
 235         struct seg6_pernet_data *sdata;
 236
 237         sdata = seg6_pernet(net);
 238
 239         if (!info->attrs[SEG6_ATTR_DST])
 240                 return -EINVAL;
 241
 242         val = nla_data(info->attrs[SEG6_ATTR_DST]);
 243         t_new = kmemdup(val, sizeof(*val), GFP_KERNEL);
 244         if (!t_new)
 245                 return -ENOMEM;
 246
 247         mutex_lock(&sdata->lock);
 248
 249         t_old = sdata->tun_src;
 250         rcu_assign_pointer(sdata->tun_src, t_new);
 251
 252         mutex_unlock(&sdata->lock);
 253
 254         synchronize_net();
 255         kfree(t_old);
 256
 257         return 0;
 258 }
 259
 260 static int seg6_genl_get_tunsrc(struct sk_buff *skb, struct genl_info *info)
 261 {
 262         struct net *net = genl_info_net(info);
 263         struct in6_addr *tun_src;
 264         struct sk_buff *msg;
 265         void *hdr;
 266
 267         msg = genlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
 268         if (!msg)
 269                 return -ENOMEM;
 270
 271         hdr = genlmsg_put(msg, info->snd_portid, info->snd_seq,
 272                           &seg6_genl_family, 0, SEG6_CMD_GET_TUNSRC);
 273         if (!hdr)
 274                 goto free_msg;
 275
 276         rcu_read_lock();
 277         tun_src = rcu_dereference(seg6_pernet(net)->tun_src);
 278
 279         if (nla_put(msg, SEG6_ATTR_DST, sizeof(struct in6_addr), tun_src))
 280                 goto nla_put_failure;
 281
 282         rcu_read_unlock();
 283
 284         genlmsg_end(msg, hdr);
 285         return genlmsg_reply(msg, info);
 286
 287 nla_put_failure:
 288         rcu_read_unlock();
 289 free_msg:
 290         nlmsg_free(msg);
 291         return -ENOMEM;
 292 }
 293
 294 #ifdef CONFIG_IPV6_SEG6_HMAC
 295
 296 static int __seg6_hmac_fill_info(struct seg6_hmac_info *hinfo,
 297                                  struct sk_buff *msg)
 298 {
 299         if (nla_put_u32(msg, SEG6_ATTR_HMACKEYID, hinfo->hmackeyid) ||
 300             nla_put_u8(msg, SEG6_ATTR_SECRETLEN, hinfo->slen) ||
 301             nla_put(msg, SEG6_ATTR_SECRET, hinfo->slen, hinfo->secret) ||
 302             nla_put_u8(msg, SEG6_ATTR_ALGID, hinfo->alg_id))
 303                 return -1;
 304
 305         return 0;
 306 }
 307
 308 static int __seg6_genl_dumphmac_element(struct seg6_hmac_info *hinfo,
 309                                         u32 portid, u32 seq, u32 flags,
 310                                         struct sk_buff *skb, u8 cmd)
 311 {
 312         void *hdr;
 313
 314         hdr = genlmsg_put(skb, portid, seq, &seg6_genl_family, flags, cmd);
 315         if (!hdr)
 316                 return -ENOMEM;
 317
 318         if (__seg6_hmac_fill_info(hinfo, skb) < 0)
 319                 goto nla_put_failure;
 320
 321         genlmsg_end(skb, hdr);
 322         return 0;
 323
 324 nla_put_failure:
 325         genlmsg_cancel(skb, hdr);
 326         return -EMSGSIZE;
 327 }
 328
 329 static int seg6_genl_dumphmac_start(struct netlink_callback *cb)
 330 {
 331         struct net *net = sock_net(cb->skb->sk);
 332         struct seg6_pernet_data *sdata;
 333         struct rhashtable_iter *iter;
 334
 335         sdata = seg6_pernet(net);
 336         iter = (struct rhashtable_iter *)cb->args[0];
 337
 338         if (!iter) {
 339                 iter = kmalloc(sizeof(*iter), GFP_KERNEL);
 340                 if (!iter)
 341                         return -ENOMEM;
 342
 343                 cb->args[0] = (long)iter;
 344         }
 345
 346         rhashtable_walk_enter(&sdata->hmac_infos, iter);
 347
 348         return 0;
 349 }
 350
 351 static int seg6_genl_dumphmac_done(struct netlink_callback *cb)
 352 {
 353         struct rhashtable_iter *iter = (struct rhashtable_iter *)cb->args[0];
 354
 355         rhashtable_walk_exit(iter);
 356
 357         kfree(iter);
 358
 359         return 0;
 360 }
 361
 362 static int seg6_genl_dumphmac(struct sk_buff *skb, struct netlink_callback *cb)
 363 {
 364         struct rhashtable_iter *iter = (struct rhashtable_iter *)cb->args[0];
 365         struct seg6_hmac_info *hinfo;
 366         int ret;
 367
 368         rhashtable_walk_start(iter);
 369
 370         for (;;) {
 371                 hinfo = rhashtable_walk_next(iter);
 372
 373                 if (IS_ERR(hinfo)) {
 374                         if (PTR_ERR(hinfo) == -EAGAIN)
 375                                 continue;
 376                         ret = PTR_ERR(hinfo);
 377                         goto done;
 378                 } else if (!hinfo) {
 379                         break;
 380                 }
 381
 382                 ret = __seg6_genl_dumphmac_element(hinfo,
 383                                                    NETLINK_CB(cb->skb).portid,
 384                                                    cb->nlh->nlmsg_seq,
 385                                                    NLM_F_MULTI,
 386                                                    skb, SEG6_CMD_DUMPHMAC);
 387                 if (ret)
 388                         goto done;
 389         }
 390
 391         ret = skb->len;
 392
 393 done:
 394         rhashtable_walk_stop(iter);
 395         return ret;
 396 }
 397
 398 #else
 399
 400 static int seg6_genl_dumphmac_start(struct netlink_callback *cb)
 401 {
 402         return 0;
 403 }
 404
 405 static int seg6_genl_dumphmac_done(struct netlink_callback *cb)
 406 {
 407         return 0;
 408 }
 409
 410 static int seg6_genl_dumphmac(struct sk_buff *skb, struct netlink_callback *cb)
 411 {
 412         return -ENOTSUPP;
 413 }
 414
 415 #endif
 416
 417 static int __net_init seg6_net_init(struct net *net)
 418 {
 419         struct seg6_pernet_data *sdata;
 420
 421         sdata = kzalloc(sizeof(*sdata), GFP_KERNEL);
 422         if (!sdata)
 423                 return -ENOMEM;
 424
 425         mutex_init(&sdata->lock);
 426
 427         sdata->tun_src = kzalloc(sizeof(*sdata->tun_src), GFP_KERNEL);
 428         if (!sdata->tun_src) {
 429                 kfree(sdata);
 430                 return -ENOMEM;
 431         }
 432
 433         net->ipv6.seg6_data = sdata;
 434
 435 #ifdef CONFIG_IPV6_SEG6_HMAC
 436         if (seg6_hmac_net_init(net)) {
 437                 kfree(rcu_dereference_raw(sdata->tun_src));
 438                 kfree(sdata);
 439                 return -ENOMEM;
 440         }
 441 #endif
 442
 443         return 0;
 444 }
 445
 446 static void __net_exit seg6_net_exit(struct net *net)
 447 {
 448         struct seg6_pernet_data *sdata = seg6_pernet(net);
 449
 450 #ifdef CONFIG_IPV6_SEG6_HMAC
 451         seg6_hmac_net_exit(net);
 452 #endif
 453
 454         kfree(rcu_dereference_raw(sdata->tun_src));
 455         kfree(sdata);
 456 }
 457
 458 static struct pernet_operations ip6_segments_ops = {
 459         .init = seg6_net_init,
 460         .exit = seg6_net_exit,
 461 };
 462
 463 static const struct genl_ops seg6_genl_ops[] = {
 464         {
 465                 .cmd    = SEG6_CMD_SETHMAC,
 466                 .validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
 467                 .doit   = seg6_genl_sethmac,
 468                 .flags  = GENL_ADMIN_PERM,
 469         },
 470         {
 471                 .cmd    = SEG6_CMD_DUMPHMAC,
 472                 .validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
 473                 .start  = seg6_genl_dumphmac_start,
 474                 .dumpit = seg6_genl_dumphmac,
 475                 .done   = seg6_genl_dumphmac_done,
 476                 .flags  = GENL_ADMIN_PERM,
 477         },
 478         {
 479                 .cmd    = SEG6_CMD_SET_TUNSRC,
 480                 .validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
 481                 .doit   = seg6_genl_set_tunsrc,
 482                 .flags  = GENL_ADMIN_PERM,
 483         },
 484         {
 485                 .cmd    = SEG6_CMD_GET_TUNSRC,
 486                 .validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
 487                 .doit   = seg6_genl_get_tunsrc,
 488                 .flags  = GENL_ADMIN_PERM,
 489         },
 490 };
 491
 492 static struct genl_family seg6_genl_family __ro_after_init = {
 493         .hdrsize        = 0,
 494         .name           = SEG6_GENL_NAME,
 495         .version        = SEG6_GENL_VERSION,
 496         .maxattr        = SEG6_ATTR_MAX,
 497         .policy = seg6_genl_policy,
 498         .netnsok        = true,
 499         .parallel_ops   = true,
 500         .ops            = seg6_genl_ops,
 501         .n_ops          = ARRAY_SIZE(seg6_genl_ops),
 502         .module         = THIS_MODULE,
 503 };
 504
 505 int __init seg6_init(void)
 506 {
 507         int err;
 508
 509         err = genl_register_family(&seg6_genl_family);
 510         if (err)
 511                 goto out;
 512
 513         err = register_pernet_subsys(&ip6_segments_ops);
 514         if (err)
 515                 goto out_unregister_genl;
 516
 517 #ifdef CONFIG_IPV6_SEG6_LWTUNNEL
 518         err = seg6_iptunnel_init();
 519         if (err)
 520                 goto out_unregister_pernet;
 521
 522         err = seg6_local_init();
 523         if (err)
 524                 goto out_unregister_pernet;
 525 #endif
 526
 527 #ifdef CONFIG_IPV6_SEG6_HMAC
 528         err = seg6_hmac_init();
 529         if (err)
 530                 goto out_unregister_iptun;
 531 #endif
 532
 533         pr_info("Segment Routing with IPv6\n");
 534
 535 out:
 536         return err;
 537 #ifdef CONFIG_IPV6_SEG6_HMAC
 538 out_unregister_iptun:
 539 #ifdef CONFIG_IPV6_SEG6_LWTUNNEL
 540         seg6_local_exit();
 541         seg6_iptunnel_exit();
 542 #endif
 543 #endif
 544 #ifdef CONFIG_IPV6_SEG6_LWTUNNEL
 545 out_unregister_pernet:
 546         unregister_pernet_subsys(&ip6_segments_ops);
 547 #endif
 548 out_unregister_genl:
 549         genl_unregister_family(&seg6_genl_family);
 550         goto out;
 551 }
 552
 553 void seg6_exit(void)
 554 {
 555 #ifdef CONFIG_IPV6_SEG6_HMAC
 556         seg6_hmac_exit();
 557 #endif
 558 #ifdef CONFIG_IPV6_SEG6_LWTUNNEL
 559         seg6_iptunnel_exit();
 560 #endif
 561         unregister_pernet_subsys(&ip6_segments_ops);
 562         genl_unregister_family(&seg6_genl_family);
 563 }