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 static struct genl_family seg6_genl_family;
 108
 109 static const struct nla_policy seg6_genl_policy[SEG6_ATTR_MAX + 1] = {
 110         [SEG6_ATTR_DST]                         = { .type = NLA_BINARY,
 111                 .len = sizeof(struct in6_addr) },
 112         [SEG6_ATTR_DSTLEN]                      = { .type = NLA_S32, },
 113         [SEG6_ATTR_HMACKEYID]           = { .type = NLA_U32, },
 114         [SEG6_ATTR_SECRET]                      = { .type = NLA_BINARY, },
 115         [SEG6_ATTR_SECRETLEN]           = { .type = NLA_U8, },
 116         [SEG6_ATTR_ALGID]                       = { .type = NLA_U8, },
 117         [SEG6_ATTR_HMACINFO]            = { .type = NLA_NESTED, },
 118 };
 119
 120 #ifdef CONFIG_IPV6_SEG6_HMAC
 121
 122 static int seg6_genl_sethmac(struct sk_buff *skb, struct genl_info *info)
 123 {
 124         struct net *net = genl_info_net(info);
 125         struct seg6_pernet_data *sdata;
 126         struct seg6_hmac_info *hinfo;
 127         u32 hmackeyid;
 128         char *secret;
 129         int err = 0;
 130         u8 algid;
 131         u8 slen;
 132
 133         sdata = seg6_pernet(net);
 134
 135         if (!info->attrs[SEG6_ATTR_HMACKEYID] ||
 136             !info->attrs[SEG6_ATTR_SECRETLEN] ||
 137             !info->attrs[SEG6_ATTR_ALGID])
 138                 return -EINVAL;
 139
 140         hmackeyid = nla_get_u32(info->attrs[SEG6_ATTR_HMACKEYID]);
 141         slen = nla_get_u8(info->attrs[SEG6_ATTR_SECRETLEN]);
 142         algid = nla_get_u8(info->attrs[SEG6_ATTR_ALGID]);
 143
 144         if (hmackeyid == 0)
 145                 return -EINVAL;
 146
 147         if (slen > SEG6_HMAC_SECRET_LEN)
 148                 return -EINVAL;
 149
 150         mutex_lock(&sdata->lock);
 151         hinfo = seg6_hmac_info_lookup(net, hmackeyid);
 152
 153         if (!slen) {
 154                 err = seg6_hmac_info_del(net, hmackeyid);
 155
 156                 goto out_unlock;
 157         }
 158
 159         if (!info->attrs[SEG6_ATTR_SECRET]) {
 160                 err = -EINVAL;
 161                 goto out_unlock;
 162         }
 163
 164         if (hinfo) {
 165                 err = seg6_hmac_info_del(net, hmackeyid);
 166                 if (err)
 167                         goto out_unlock;
 168         }
 169
 170         secret = (char *)nla_data(info->attrs[SEG6_ATTR_SECRET]);
 171
 172         hinfo = kzalloc(sizeof(*hinfo), GFP_KERNEL);
 173         if (!hinfo) {
 174                 err = -ENOMEM;
 175                 goto out_unlock;
 176         }
 177
 178         memcpy(hinfo->secret, secret, slen);
 179         hinfo->slen = slen;
 180         hinfo->alg_id = algid;
 181         hinfo->hmackeyid = hmackeyid;
 182
 183         err = seg6_hmac_info_add(net, hmackeyid, hinfo);
 184         if (err)
 185                 kfree(hinfo);
 186
 187 out_unlock:
 188         mutex_unlock(&sdata->lock);
 189         return err;
 190 }
 191
 192 #else
 193
 194 static int seg6_genl_sethmac(struct sk_buff *skb, struct genl_info *info)
 195 {
 196         return -ENOTSUPP;
 197 }
 198
 199 #endif
 200
 201 static int seg6_genl_set_tunsrc(struct sk_buff *skb, struct genl_info *info)
 202 {
 203         struct net *net = genl_info_net(info);
 204         struct in6_addr *val, *t_old, *t_new;
 205         struct seg6_pernet_data *sdata;
 206
 207         sdata = seg6_pernet(net);
 208
 209         if (!info->attrs[SEG6_ATTR_DST])
 210                 return -EINVAL;
 211
 212         val = nla_data(info->attrs[SEG6_ATTR_DST]);
 213         t_new = kmemdup(val, sizeof(*val), GFP_KERNEL);
 214         if (!t_new)
 215                 return -ENOMEM;
 216
 217         mutex_lock(&sdata->lock);
 218
 219         t_old = sdata->tun_src;
 220         rcu_assign_pointer(sdata->tun_src, t_new);
 221
 222         mutex_unlock(&sdata->lock);
 223
 224         synchronize_net();
 225         kfree(t_old);
 226
 227         return 0;
 228 }
 229
 230 static int seg6_genl_get_tunsrc(struct sk_buff *skb, struct genl_info *info)
 231 {
 232         struct net *net = genl_info_net(info);
 233         struct in6_addr *tun_src;
 234         struct sk_buff *msg;
 235         void *hdr;
 236
 237         msg = genlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
 238         if (!msg)
 239                 return -ENOMEM;
 240
 241         hdr = genlmsg_put(msg, info->snd_portid, info->snd_seq,
 242                           &seg6_genl_family, 0, SEG6_CMD_GET_TUNSRC);
 243         if (!hdr)
 244                 goto free_msg;
 245
 246         rcu_read_lock();
 247         tun_src = rcu_dereference(seg6_pernet(net)->tun_src);
 248
 249         if (nla_put(msg, SEG6_ATTR_DST, sizeof(struct in6_addr), tun_src))
 250                 goto nla_put_failure;
 251
 252         rcu_read_unlock();
 253
 254         genlmsg_end(msg, hdr);
 255         return genlmsg_reply(msg, info);
 256
 257 nla_put_failure:
 258         rcu_read_unlock();
 259 free_msg:
 260         nlmsg_free(msg);
 261         return -ENOMEM;
 262 }
 263
 264 #ifdef CONFIG_IPV6_SEG6_HMAC
 265
 266 static int __seg6_hmac_fill_info(struct seg6_hmac_info *hinfo,
 267                                  struct sk_buff *msg)
 268 {
 269         if (nla_put_u32(msg, SEG6_ATTR_HMACKEYID, hinfo->hmackeyid) ||
 270             nla_put_u8(msg, SEG6_ATTR_SECRETLEN, hinfo->slen) ||
 271             nla_put(msg, SEG6_ATTR_SECRET, hinfo->slen, hinfo->secret) ||
 272             nla_put_u8(msg, SEG6_ATTR_ALGID, hinfo->alg_id))
 273                 return -1;
 274
 275         return 0;
 276 }
 277
 278 static int __seg6_genl_dumphmac_element(struct seg6_hmac_info *hinfo,
 279                                         u32 portid, u32 seq, u32 flags,
 280                                         struct sk_buff *skb, u8 cmd)
 281 {
 282         void *hdr;
 283
 284         hdr = genlmsg_put(skb, portid, seq, &seg6_genl_family, flags, cmd);
 285         if (!hdr)
 286                 return -ENOMEM;
 287
 288         if (__seg6_hmac_fill_info(hinfo, skb) < 0)
 289                 goto nla_put_failure;
 290
 291         genlmsg_end(skb, hdr);
 292         return 0;
 293
 294 nla_put_failure:
 295         genlmsg_cancel(skb, hdr);
 296         return -EMSGSIZE;
 297 }
 298
 299 static int seg6_genl_dumphmac_start(struct netlink_callback *cb)
 300 {
 301         struct net *net = sock_net(cb->skb->sk);
 302         struct seg6_pernet_data *sdata;
 303         struct rhashtable_iter *iter;
 304
 305         sdata = seg6_pernet(net);
 306         iter = (struct rhashtable_iter *)cb->args[0];
 307
 308         if (!iter) {
 309                 iter = kmalloc(sizeof(*iter), GFP_KERNEL);
 310                 if (!iter)
 311                         return -ENOMEM;
 312
 313                 cb->args[0] = (long)iter;
 314         }
 315
 316         rhashtable_walk_enter(&sdata->hmac_infos, iter);
 317
 318         return 0;
 319 }
 320
 321 static int seg6_genl_dumphmac_done(struct netlink_callback *cb)
 322 {
 323         struct rhashtable_iter *iter = (struct rhashtable_iter *)cb->args[0];
 324
 325         rhashtable_walk_exit(iter);
 326
 327         kfree(iter);
 328
 329         return 0;
 330 }
 331
 332 static int seg6_genl_dumphmac(struct sk_buff *skb, struct netlink_callback *cb)
 333 {
 334         struct rhashtable_iter *iter = (struct rhashtable_iter *)cb->args[0];
 335         struct seg6_hmac_info *hinfo;
 336         int ret;
 337
 338         rhashtable_walk_start(iter);
 339
 340         for (;;) {
 341                 hinfo = rhashtable_walk_next(iter);
 342
 343                 if (IS_ERR(hinfo)) {
 344                         if (PTR_ERR(hinfo) == -EAGAIN)
 345                                 continue;
 346                         ret = PTR_ERR(hinfo);
 347                         goto done;
 348                 } else if (!hinfo) {
 349                         break;
 350                 }
 351
 352                 ret = __seg6_genl_dumphmac_element(hinfo,
 353                                                    NETLINK_CB(cb->skb).portid,
 354                                                    cb->nlh->nlmsg_seq,
 355                                                    NLM_F_MULTI,
 356                                                    skb, SEG6_CMD_DUMPHMAC);
 357                 if (ret)
 358                         goto done;
 359         }
 360
 361         ret = skb->len;
 362
 363 done:
 364         rhashtable_walk_stop(iter);
 365         return ret;
 366 }
 367
 368 #else
 369
 370 static int seg6_genl_dumphmac_start(struct netlink_callback *cb)
 371 {
 372         return 0;
 373 }
 374
 375 static int seg6_genl_dumphmac_done(struct netlink_callback *cb)
 376 {
 377         return 0;
 378 }
 379
 380 static int seg6_genl_dumphmac(struct sk_buff *skb, struct netlink_callback *cb)
 381 {
 382         return -ENOTSUPP;
 383 }
 384
 385 #endif
 386
 387 static int __net_init seg6_net_init(struct net *net)
 388 {
 389         struct seg6_pernet_data *sdata;
 390
 391         sdata = kzalloc(sizeof(*sdata), GFP_KERNEL);
 392         if (!sdata)
 393                 return -ENOMEM;
 394
 395         mutex_init(&sdata->lock);
 396
 397         sdata->tun_src = kzalloc(sizeof(*sdata->tun_src), GFP_KERNEL);
 398         if (!sdata->tun_src) {
 399                 kfree(sdata);
 400                 return -ENOMEM;
 401         }
 402
 403         net->ipv6.seg6_data = sdata;
 404
 405 #ifdef CONFIG_IPV6_SEG6_HMAC
 406         seg6_hmac_net_init(net);
 407 #endif
 408
 409         return 0;
 410 }
 411
 412 static void __net_exit seg6_net_exit(struct net *net)
 413 {
 414         struct seg6_pernet_data *sdata = seg6_pernet(net);
 415
 416 #ifdef CONFIG_IPV6_SEG6_HMAC
 417         seg6_hmac_net_exit(net);
 418 #endif
 419
 420         kfree(sdata->tun_src);
 421         kfree(sdata);
 422 }
 423
 424 static struct pernet_operations ip6_segments_ops = {
 425         .init = seg6_net_init,
 426         .exit = seg6_net_exit,
 427 };
 428
 429 static const struct genl_ops seg6_genl_ops[] = {
 430         {
 431                 .cmd    = SEG6_CMD_SETHMAC,
 432                 .validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
 433                 .doit   = seg6_genl_sethmac,
 434                 .flags  = GENL_ADMIN_PERM,
 435         },
 436         {
 437                 .cmd    = SEG6_CMD_DUMPHMAC,
 438                 .validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
 439                 .start  = seg6_genl_dumphmac_start,
 440                 .dumpit = seg6_genl_dumphmac,
 441                 .done   = seg6_genl_dumphmac_done,
 442                 .flags  = GENL_ADMIN_PERM,
 443         },
 444         {
 445                 .cmd    = SEG6_CMD_SET_TUNSRC,
 446                 .validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
 447                 .doit   = seg6_genl_set_tunsrc,
 448                 .flags  = GENL_ADMIN_PERM,
 449         },
 450         {
 451                 .cmd    = SEG6_CMD_GET_TUNSRC,
 452                 .validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
 453                 .doit   = seg6_genl_get_tunsrc,
 454                 .flags  = GENL_ADMIN_PERM,
 455         },
 456 };
 457
 458 static struct genl_family seg6_genl_family __ro_after_init = {
 459         .hdrsize        = 0,
 460         .name           = SEG6_GENL_NAME,
 461         .version        = SEG6_GENL_VERSION,
 462         .maxattr        = SEG6_ATTR_MAX,
 463         .policy = seg6_genl_policy,
 464         .netnsok        = true,
 465         .parallel_ops   = true,
 466         .ops            = seg6_genl_ops,
 467         .n_ops          = ARRAY_SIZE(seg6_genl_ops),
 468         .module         = THIS_MODULE,
 469 };
 470
 471 int __init seg6_init(void)
 472 {
 473         int err;
 474
 475         err = genl_register_family(&seg6_genl_family);
 476         if (err)
 477                 goto out;
 478
 479         err = register_pernet_subsys(&ip6_segments_ops);
 480         if (err)
 481                 goto out_unregister_genl;
 482
 483 #ifdef CONFIG_IPV6_SEG6_LWTUNNEL
 484         err = seg6_iptunnel_init();
 485         if (err)
 486                 goto out_unregister_pernet;
 487
 488         err = seg6_local_init();
 489         if (err)
 490                 goto out_unregister_pernet;
 491 #endif
 492
 493 #ifdef CONFIG_IPV6_SEG6_HMAC
 494         err = seg6_hmac_init();
 495         if (err)
 496                 goto out_unregister_iptun;
 497 #endif
 498
 499         pr_info("Segment Routing with IPv6\n");
 500
 501 out:
 502         return err;
 503 #ifdef CONFIG_IPV6_SEG6_HMAC
 504 out_unregister_iptun:
 505 #ifdef CONFIG_IPV6_SEG6_LWTUNNEL
 506         seg6_local_exit();
 507         seg6_iptunnel_exit();
 508 #endif
 509 #endif
 510 #ifdef CONFIG_IPV6_SEG6_LWTUNNEL
 511 out_unregister_pernet:
 512         unregister_pernet_subsys(&ip6_segments_ops);
 513 #endif
 514 out_unregister_genl:
 515         genl_unregister_family(&seg6_genl_family);
 516         goto out;
 517 }
 518
 519 void seg6_exit(void)
 520 {
 521 #ifdef CONFIG_IPV6_SEG6_HMAC
 522         seg6_hmac_exit();
 523 #endif
 524 #ifdef CONFIG_IPV6_SEG6_LWTUNNEL
 525         seg6_iptunnel_exit();
 526 #endif
 527         unregister_pernet_subsys(&ip6_segments_ops);
 528         genl_unregister_family(&seg6_genl_family);
 529 }