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 #include <net/seg6_hmac.h>
  25
  26 bool seg6_validate_srh(struct ipv6_sr_hdr *srh, int len, bool reduced)
  27 {
  28         unsigned int tlv_offset;
  29         int max_last_entry;
  30         int trailing;
  31
  32         if (srh->type != IPV6_SRCRT_TYPE_4)
  33                 return false;
  34
  35         if (((srh->hdrlen + 1) << 3) != len)
  36                 return false;
  37
  38         if (!reduced && srh->segments_left > srh->first_segment) {
  39                 return false;
  40         } else {
  41                 max_last_entry = (srh->hdrlen / 2) - 1;
  42
  43                 if (srh->first_segment > max_last_entry)
  44                         return false;
  45
  46                 if (srh->segments_left > srh->first_segment + 1)
  47                         return false;
  48         }
  49
  50         tlv_offset = sizeof(*srh) + ((srh->first_segment + 1) << 4);
  51
  52         trailing = len - tlv_offset;
  53         if (trailing < 0)
  54                 return false;
  55
  56         while (trailing) {
  57                 struct sr6_tlv *tlv;
  58                 unsigned int tlv_len;
  59
  60                 if (trailing < sizeof(*tlv))
  61                         return false;
  62
  63                 tlv = (struct sr6_tlv *)((unsigned char *)srh + tlv_offset);
  64                 tlv_len = sizeof(*tlv) + tlv->len;
  65
  66                 trailing -= tlv_len;
  67                 if (trailing < 0)
  68                         return false;
  69
  70                 tlv_offset += tlv_len;
  71         }
  72
  73         return true;
  74 }
  75
  76 struct ipv6_sr_hdr *seg6_get_srh(struct sk_buff *skb, int flags)
  77 {
  78         struct ipv6_sr_hdr *srh;
  79         int len, srhoff = 0;
  80
  81         if (ipv6_find_hdr(skb, &srhoff, IPPROTO_ROUTING, NULL, &flags) < 0)
  82                 return NULL;
  83
  84         if (!pskb_may_pull(skb, srhoff + sizeof(*srh)))
  85                 return NULL;
  86
  87         srh = (struct ipv6_sr_hdr *)(skb->data + srhoff);
  88
  89         len = (srh->hdrlen + 1) << 3;
  90
  91         if (!pskb_may_pull(skb, srhoff + len))
  92                 return NULL;
  93
  94         /* note that pskb_may_pull may change pointers in header;
  95          * for this reason it is necessary to reload them when needed.
  96          */
  97         srh = (struct ipv6_sr_hdr *)(skb->data + srhoff);
  98
  99         if (!seg6_validate_srh(srh, len, true))
 100                 return NULL;
 101
 102         return srh;
 103 }
 104
 105 /* Determine if an ICMP invoking packet contains a segment routing
 106  * header.  If it does, extract the offset to the true destination
 107  * address, which is in the first segment address.
 108  */
 109 void seg6_icmp_srh(struct sk_buff *skb, struct inet6_skb_parm *opt)
 110 {
 111         __u16 network_header = skb->network_header;
 112         struct ipv6_sr_hdr *srh;
 113
 114         /* Update network header to point to the invoking packet
 115          * inside the ICMP packet, so we can use the seg6_get_srh()
 116          * helper.
 117          */
 118         skb_reset_network_header(skb);
 119
 120         srh = seg6_get_srh(skb, 0);
 121         if (!srh)
 122                 goto out;
 123
 124         if (srh->type != IPV6_SRCRT_TYPE_4)
 125                 goto out;
 126
 127         opt->flags |= IP6SKB_SEG6;
 128         opt->srhoff = (unsigned char *)srh - skb->data;
 129
 130 out:
 131         /* Restore the network header back to the ICMP packet */
 132         skb->network_header = network_header;
 133 }
 134
 135 static struct genl_family seg6_genl_family;
 136
 137 static const struct nla_policy seg6_genl_policy[SEG6_ATTR_MAX + 1] = {
 138         [SEG6_ATTR_DST]                         = { .type = NLA_BINARY,
 139                 .len = sizeof(struct in6_addr) },
 140         [SEG6_ATTR_DSTLEN]                      = { .type = NLA_S32, },
 141         [SEG6_ATTR_HMACKEYID]           = { .type = NLA_U32, },
 142         [SEG6_ATTR_SECRET]                      = { .type = NLA_BINARY, },
 143         [SEG6_ATTR_SECRETLEN]           = { .type = NLA_U8, },
 144         [SEG6_ATTR_ALGID]                       = { .type = NLA_U8, },
 145         [SEG6_ATTR_HMACINFO]            = { .type = NLA_NESTED, },
 146 };
 147
 148 #ifdef CONFIG_IPV6_SEG6_HMAC
 149
 150 static int seg6_genl_sethmac(struct sk_buff *skb, struct genl_info *info)
 151 {
 152         struct net *net = genl_info_net(info);
 153         struct seg6_pernet_data *sdata;
 154         struct seg6_hmac_info *hinfo;
 155         u32 hmackeyid;
 156         char *secret;
 157         int err = 0;
 158         u8 algid;
 159         u8 slen;
 160
 161         sdata = seg6_pernet(net);
 162
 163         if (!info->attrs[SEG6_ATTR_HMACKEYID] ||
 164             !info->attrs[SEG6_ATTR_SECRETLEN] ||
 165             !info->attrs[SEG6_ATTR_ALGID])
 166                 return -EINVAL;
 167
 168         hmackeyid = nla_get_u32(info->attrs[SEG6_ATTR_HMACKEYID]);
 169         slen = nla_get_u8(info->attrs[SEG6_ATTR_SECRETLEN]);
 170         algid = nla_get_u8(info->attrs[SEG6_ATTR_ALGID]);
 171
 172         if (hmackeyid == 0)
 173                 return -EINVAL;
 174
 175         if (slen > SEG6_HMAC_SECRET_LEN)
 176                 return -EINVAL;
 177
 178         mutex_lock(&sdata->lock);
 179         hinfo = seg6_hmac_info_lookup(net, hmackeyid);
 180
 181         if (!slen) {
 182                 err = seg6_hmac_info_del(net, hmackeyid);
 183
 184                 goto out_unlock;
 185         }
 186
 187         if (!info->attrs[SEG6_ATTR_SECRET]) {
 188                 err = -EINVAL;
 189                 goto out_unlock;
 190         }
 191
 192         if (slen > nla_len(info->attrs[SEG6_ATTR_SECRET])) {
 193                 err = -EINVAL;
 194                 goto out_unlock;
 195         }
 196
 197         if (hinfo) {
 198                 err = seg6_hmac_info_del(net, hmackeyid);
 199                 if (err)
 200                         goto out_unlock;
 201         }
 202
 203         secret = (char *)nla_data(info->attrs[SEG6_ATTR_SECRET]);
 204
 205         hinfo = kzalloc(sizeof(*hinfo), GFP_KERNEL);
 206         if (!hinfo) {
 207                 err = -ENOMEM;
 208                 goto out_unlock;
 209         }
 210
 211         memcpy(hinfo->secret, secret, slen);
 212         hinfo->slen = slen;
 213         hinfo->alg_id = algid;
 214         hinfo->hmackeyid = hmackeyid;
 215
 216         err = seg6_hmac_info_add(net, hmackeyid, hinfo);
 217         if (err)
 218                 kfree(hinfo);
 219
 220 out_unlock:
 221         mutex_unlock(&sdata->lock);
 222         return err;
 223 }
 224
 225 #else
 226
 227 static int seg6_genl_sethmac(struct sk_buff *skb, struct genl_info *info)
 228 {
 229         return -ENOTSUPP;
 230 }
 231
 232 #endif
 233
 234 static int seg6_genl_set_tunsrc(struct sk_buff *skb, struct genl_info *info)
 235 {
 236         struct net *net = genl_info_net(info);
 237         struct in6_addr *val, *t_old, *t_new;
 238         struct seg6_pernet_data *sdata;
 239
 240         sdata = seg6_pernet(net);
 241
 242         if (!info->attrs[SEG6_ATTR_DST])
 243                 return -EINVAL;
 244
 245         val = nla_data(info->attrs[SEG6_ATTR_DST]);
 246         t_new = kmemdup(val, sizeof(*val), GFP_KERNEL);
 247         if (!t_new)
 248                 return -ENOMEM;
 249
 250         mutex_lock(&sdata->lock);
 251
 252         t_old = sdata->tun_src;
 253         rcu_assign_pointer(sdata->tun_src, t_new);
 254
 255         mutex_unlock(&sdata->lock);
 256
 257         synchronize_net();
 258         kfree(t_old);
 259
 260         return 0;
 261 }
 262
 263 static int seg6_genl_get_tunsrc(struct sk_buff *skb, struct genl_info *info)
 264 {
 265         struct net *net = genl_info_net(info);
 266         struct in6_addr *tun_src;
 267         struct sk_buff *msg;
 268         void *hdr;
 269
 270         msg = genlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
 271         if (!msg)
 272                 return -ENOMEM;
 273
 274         hdr = genlmsg_put(msg, info->snd_portid, info->snd_seq,
 275                           &seg6_genl_family, 0, SEG6_CMD_GET_TUNSRC);
 276         if (!hdr)
 277                 goto free_msg;
 278
 279         rcu_read_lock();
 280         tun_src = rcu_dereference(seg6_pernet(net)->tun_src);
 281
 282         if (nla_put(msg, SEG6_ATTR_DST, sizeof(struct in6_addr), tun_src))
 283                 goto nla_put_failure;
 284
 285         rcu_read_unlock();
 286
 287         genlmsg_end(msg, hdr);
 288         return genlmsg_reply(msg, info);
 289
 290 nla_put_failure:
 291         rcu_read_unlock();
 292 free_msg:
 293         nlmsg_free(msg);
 294         return -ENOMEM;
 295 }
 296
 297 #ifdef CONFIG_IPV6_SEG6_HMAC
 298
 299 static int __seg6_hmac_fill_info(struct seg6_hmac_info *hinfo,
 300                                  struct sk_buff *msg)
 301 {
 302         if (nla_put_u32(msg, SEG6_ATTR_HMACKEYID, hinfo->hmackeyid) ||
 303             nla_put_u8(msg, SEG6_ATTR_SECRETLEN, hinfo->slen) ||
 304             nla_put(msg, SEG6_ATTR_SECRET, hinfo->slen, hinfo->secret) ||
 305             nla_put_u8(msg, SEG6_ATTR_ALGID, hinfo->alg_id))
 306                 return -1;
 307
 308         return 0;
 309 }
 310
 311 static int __seg6_genl_dumphmac_element(struct seg6_hmac_info *hinfo,
 312                                         u32 portid, u32 seq, u32 flags,
 313                                         struct sk_buff *skb, u8 cmd)
 314 {
 315         void *hdr;
 316
 317         hdr = genlmsg_put(skb, portid, seq, &seg6_genl_family, flags, cmd);
 318         if (!hdr)
 319                 return -ENOMEM;
 320
 321         if (__seg6_hmac_fill_info(hinfo, skb) < 0)
 322                 goto nla_put_failure;
 323
 324         genlmsg_end(skb, hdr);
 325         return 0;
 326
 327 nla_put_failure:
 328         genlmsg_cancel(skb, hdr);
 329         return -EMSGSIZE;
 330 }
 331
 332 static int seg6_genl_dumphmac_start(struct netlink_callback *cb)
 333 {
 334         struct net *net = sock_net(cb->skb->sk);
 335         struct seg6_pernet_data *sdata;
 336         struct rhashtable_iter *iter;
 337
 338         sdata = seg6_pernet(net);
 339         iter = (struct rhashtable_iter *)cb->args[0];
 340
 341         if (!iter) {
 342                 iter = kmalloc(sizeof(*iter), GFP_KERNEL);
 343                 if (!iter)
 344                         return -ENOMEM;
 345
 346                 cb->args[0] = (long)iter;
 347         }
 348
 349         rhashtable_walk_enter(&sdata->hmac_infos, iter);
 350
 351         return 0;
 352 }
 353
 354 static int seg6_genl_dumphmac_done(struct netlink_callback *cb)
 355 {
 356         struct rhashtable_iter *iter = (struct rhashtable_iter *)cb->args[0];
 357
 358         rhashtable_walk_exit(iter);
 359
 360         kfree(iter);
 361
 362         return 0;
 363 }
 364
 365 static int seg6_genl_dumphmac(struct sk_buff *skb, struct netlink_callback *cb)
 366 {
 367         struct rhashtable_iter *iter = (struct rhashtable_iter *)cb->args[0];
 368         struct seg6_hmac_info *hinfo;
 369         int ret;
 370
 371         rhashtable_walk_start(iter);
 372
 373         for (;;) {
 374                 hinfo = rhashtable_walk_next(iter);
 375
 376                 if (IS_ERR(hinfo)) {
 377                         if (PTR_ERR(hinfo) == -EAGAIN)
 378                                 continue;
 379                         ret = PTR_ERR(hinfo);
 380                         goto done;
 381                 } else if (!hinfo) {
 382                         break;
 383                 }
 384
 385                 ret = __seg6_genl_dumphmac_element(hinfo,
 386                                                    NETLINK_CB(cb->skb).portid,
 387                                                    cb->nlh->nlmsg_seq,
 388                                                    NLM_F_MULTI,
 389                                                    skb, SEG6_CMD_DUMPHMAC);
 390                 if (ret)
 391                         goto done;
 392         }
 393
 394         ret = skb->len;
 395
 396 done:
 397         rhashtable_walk_stop(iter);
 398         return ret;
 399 }
 400
 401 #else
 402
 403 static int seg6_genl_dumphmac_start(struct netlink_callback *cb)
 404 {
 405         return 0;
 406 }
 407
 408 static int seg6_genl_dumphmac_done(struct netlink_callback *cb)
 409 {
 410         return 0;
 411 }
 412
 413 static int seg6_genl_dumphmac(struct sk_buff *skb, struct netlink_callback *cb)
 414 {
 415         return -ENOTSUPP;
 416 }
 417
 418 #endif
 419
 420 static int __net_init seg6_net_init(struct net *net)
 421 {
 422         struct seg6_pernet_data *sdata;
 423
 424         sdata = kzalloc(sizeof(*sdata), GFP_KERNEL);
 425         if (!sdata)
 426                 return -ENOMEM;
 427
 428         mutex_init(&sdata->lock);
 429
 430         sdata->tun_src = kzalloc(sizeof(*sdata->tun_src), GFP_KERNEL);
 431         if (!sdata->tun_src) {
 432                 kfree(sdata);
 433                 return -ENOMEM;
 434         }
 435
 436         net->ipv6.seg6_data = sdata;
 437
 438         if (seg6_hmac_net_init(net)) {
 439                 kfree(rcu_dereference_raw(sdata->tun_src));
 440                 kfree(sdata);
 441                 return -ENOMEM;
 442         }
 443
 444         return 0;
 445 }
 446
 447 static void __net_exit seg6_net_exit(struct net *net)
 448 {
 449         struct seg6_pernet_data *sdata = seg6_pernet(net);
 450
 451         seg6_hmac_net_exit(net);
 452
 453         kfree(rcu_dereference_raw(sdata->tun_src));
 454         kfree(sdata);
 455 }
 456
 457 static struct pernet_operations ip6_segments_ops = {
 458         .init = seg6_net_init,
 459         .exit = seg6_net_exit,
 460 };
 461
 462 static const struct genl_ops seg6_genl_ops[] = {
 463         {
 464                 .cmd    = SEG6_CMD_SETHMAC,
 465                 .validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
 466                 .doit   = seg6_genl_sethmac,
 467                 .flags  = GENL_ADMIN_PERM,
 468         },
 469         {
 470                 .cmd    = SEG6_CMD_DUMPHMAC,
 471                 .validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
 472                 .start  = seg6_genl_dumphmac_start,
 473                 .dumpit = seg6_genl_dumphmac,
 474                 .done   = seg6_genl_dumphmac_done,
 475                 .flags  = GENL_ADMIN_PERM,
 476         },
 477         {
 478                 .cmd    = SEG6_CMD_SET_TUNSRC,
 479                 .validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
 480                 .doit   = seg6_genl_set_tunsrc,
 481                 .flags  = GENL_ADMIN_PERM,
 482         },
 483         {
 484                 .cmd    = SEG6_CMD_GET_TUNSRC,
 485                 .validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
 486                 .doit   = seg6_genl_get_tunsrc,
 487                 .flags  = GENL_ADMIN_PERM,
 488         },
 489 };
 490
 491 static struct genl_family seg6_genl_family __ro_after_init = {
 492         .hdrsize        = 0,
 493         .name           = SEG6_GENL_NAME,
 494         .version        = SEG6_GENL_VERSION,
 495         .maxattr        = SEG6_ATTR_MAX,
 496         .policy = seg6_genl_policy,
 497         .netnsok        = true,
 498         .parallel_ops   = true,
 499         .ops            = seg6_genl_ops,
 500         .n_ops          = ARRAY_SIZE(seg6_genl_ops),
 501         .resv_start_op  = SEG6_CMD_GET_TUNSRC + 1,
 502         .module         = THIS_MODULE,
 503 };
 504
 505 int __init seg6_init(void)
 506 {
 507         int err;
 508
 509         err = register_pernet_subsys(&ip6_segments_ops);
 510         if (err)
 511                 goto out;
 512
 513         err = genl_register_family(&seg6_genl_family);
 514         if (err)
 515                 goto out_unregister_pernet;
 516
 517         err = seg6_iptunnel_init();
 518         if (err)
 519                 goto out_unregister_genl;
 520
 521         err = seg6_local_init();
 522         if (err)
 523                 goto out_unregister_iptun;
 524
 525         err = seg6_hmac_init();
 526         if (err)
 527                 goto out_unregister_seg6;
 528
 529         pr_info("Segment Routing with IPv6\n");
 530
 531 out:
 532         return err;
 533 out_unregister_seg6:
 534         seg6_local_exit();
 535 out_unregister_iptun:
 536         seg6_iptunnel_exit();
 537 out_unregister_genl:
 538         genl_unregister_family(&seg6_genl_family);
 539 out_unregister_pernet:
 540         unregister_pernet_subsys(&ip6_segments_ops);
 541         goto out;
 542 }
 543
 544 void seg6_exit(void)
 545 {
 546         seg6_hmac_exit();
 547         seg6_local_exit();
 548         seg6_iptunnel_exit();
 549         genl_unregister_family(&seg6_genl_family);
 550         unregister_pernet_subsys(&ip6_segments_ops);
 551 }