net/ipv4/fib_semantics.c

   1 /*
   2  * INET         An implementation of the TCP/IP protocol suite for the LINUX
   3  *              operating system.  INET is implemented using the  BSD Socket
   4  *              interface as the means of communication with the user level.
   5  *
   6  *              IPv4 Forwarding Information Base: semantics.
   7  *
   8  * Authors:     Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
   9  *
  10  *              This program is free software; you can redistribute it and/or
  11  *              modify it under the terms of the GNU General Public License
  12  *              as published by the Free Software Foundation; either version
  13  *              2 of the License, or (at your option) any later version.
  14  */
  15
  16 #include <linux/uaccess.h>
  17 #include <linux/bitops.h>
  18 #include <linux/types.h>
  19 #include <linux/kernel.h>
  20 #include <linux/jiffies.h>
  21 #include <linux/mm.h>
  22 #include <linux/string.h>
  23 #include <linux/socket.h>
  24 #include <linux/sockios.h>
  25 #include <linux/errno.h>
  26 #include <linux/in.h>
  27 #include <linux/inet.h>
  28 #include <linux/inetdevice.h>
  29 #include <linux/netdevice.h>
  30 #include <linux/if_arp.h>
  31 #include <linux/proc_fs.h>
  32 #include <linux/skbuff.h>
  33 #include <linux/init.h>
  34 #include <linux/slab.h>
  35
  36 #include <net/arp.h>
  37 #include <net/ip.h>
  38 #include <net/protocol.h>
  39 #include <net/route.h>
  40 #include <net/tcp.h>
  41 #include <net/sock.h>
  42 #include <net/ip_fib.h>
  43 #include <net/netlink.h>
  44 #include <net/nexthop.h>
  45 #include <net/lwtunnel.h>
  46
  47 #include "fib_lookup.h"
  48
  49 static DEFINE_SPINLOCK(fib_info_lock);
  50 static struct hlist_head *fib_info_hash;
  51 static struct hlist_head *fib_info_laddrhash;
  52 static unsigned int fib_info_hash_size;
  53 static unsigned int fib_info_cnt;
  54
  55 #define DEVINDEX_HASHBITS 8
  56 #define DEVINDEX_HASHSIZE (1U << DEVINDEX_HASHBITS)
  57 static struct hlist_head fib_info_devhash[DEVINDEX_HASHSIZE];
  58
  59 #ifdef CONFIG_IP_ROUTE_MULTIPATH
  60 u32 fib_multipath_secret __read_mostly;
  61
  62 #define for_nexthops(fi) {                                              \
  63         int nhsel; const struct fib_nh *nh;                             \
  64         for (nhsel = 0, nh = (fi)->fib_nh;                              \
  65              nhsel < (fi)->fib_nhs;                                     \
  66              nh++, nhsel++)
  67
  68 #define change_nexthops(fi) {                                           \
  69         int nhsel; struct fib_nh *nexthop_nh;                           \
  70         for (nhsel = 0, nexthop_nh = (struct fib_nh *)((fi)->fib_nh);   \
  71              nhsel < (fi)->fib_nhs;                                     \
  72              nexthop_nh++, nhsel++)
  73
  74 #else /* CONFIG_IP_ROUTE_MULTIPATH */
  75
  76 /* Hope, that gcc will optimize it to get rid of dummy loop */
  77
  78 #define for_nexthops(fi) {                                              \
  79         int nhsel; const struct fib_nh *nh = (fi)->fib_nh;              \
  80         for (nhsel = 0; nhsel < 1; nhsel++)
  81
  82 #define change_nexthops(fi) {                                           \
  83         int nhsel;                                                      \
  84         struct fib_nh *nexthop_nh = (struct fib_nh *)((fi)->fib_nh);    \
  85         for (nhsel = 0; nhsel < 1; nhsel++)
  86
  87 #endif /* CONFIG_IP_ROUTE_MULTIPATH */
  88
  89 #define endfor_nexthops(fi) }
  90
  91
  92 const struct fib_prop fib_props[RTN_MAX + 1] = {
  93         [RTN_UNSPEC] = {
  94                 .error  = 0,
  95                 .scope  = RT_SCOPE_NOWHERE,
  96         },
  97         [RTN_UNICAST] = {
  98                 .error  = 0,
  99                 .scope  = RT_SCOPE_UNIVERSE,
 100         },
 101         [RTN_LOCAL] = {
 102                 .error  = 0,
 103                 .scope  = RT_SCOPE_HOST,
 104         },
 105         [RTN_BROADCAST] = {
 106                 .error  = 0,
 107                 .scope  = RT_SCOPE_LINK,
 108         },
 109         [RTN_ANYCAST] = {
 110                 .error  = 0,
 111                 .scope  = RT_SCOPE_LINK,
 112         },
 113         [RTN_MULTICAST] = {
 114                 .error  = 0,
 115                 .scope  = RT_SCOPE_UNIVERSE,
 116         },
 117         [RTN_BLACKHOLE] = {
 118                 .error  = -EINVAL,
 119                 .scope  = RT_SCOPE_UNIVERSE,
 120         },
 121         [RTN_UNREACHABLE] = {
 122                 .error  = -EHOSTUNREACH,
 123                 .scope  = RT_SCOPE_UNIVERSE,
 124         },
 125         [RTN_PROHIBIT] = {
 126                 .error  = -EACCES,
 127                 .scope  = RT_SCOPE_UNIVERSE,
 128         },
 129         [RTN_THROW] = {
 130                 .error  = -EAGAIN,
 131                 .scope  = RT_SCOPE_UNIVERSE,
 132         },
 133         [RTN_NAT] = {
 134                 .error  = -EINVAL,
 135                 .scope  = RT_SCOPE_NOWHERE,
 136         },
 137         [RTN_XRESOLVE] = {
 138                 .error  = -EINVAL,
 139                 .scope  = RT_SCOPE_NOWHERE,
 140         },
 141 };
 142
 143 static void rt_fibinfo_free(struct rtable __rcu **rtp)
 144 {
 145         struct rtable *rt = rcu_dereference_protected(*rtp, 1);
 146
 147         if (!rt)
 148                 return;
 149
 150         /* Not even needed : RCU_INIT_POINTER(*rtp, NULL);
 151          * because we waited an RCU grace period before calling
 152          * free_fib_info_rcu()
 153          */
 154
 155         dst_free(&rt->dst);
 156 }
 157
 158 static void free_nh_exceptions(struct fib_nh *nh)
 159 {
 160         struct fnhe_hash_bucket *hash;
 161         int i;
 162
 163         hash = rcu_dereference_protected(nh->nh_exceptions, 1);
 164         if (!hash)
 165                 return;
 166         for (i = 0; i < FNHE_HASH_SIZE; i++) {
 167                 struct fib_nh_exception *fnhe;
 168
 169                 fnhe = rcu_dereference_protected(hash[i].chain, 1);
 170                 while (fnhe) {
 171                         struct fib_nh_exception *next;
 172
 173                         next = rcu_dereference_protected(fnhe->fnhe_next, 1);
 174
 175                         rt_fibinfo_free(&fnhe->fnhe_rth_input);
 176                         rt_fibinfo_free(&fnhe->fnhe_rth_output);
 177
 178                         kfree(fnhe);
 179
 180                         fnhe = next;
 181                 }
 182         }
 183         kfree(hash);
 184 }
 185
 186 static void rt_fibinfo_free_cpus(struct rtable __rcu * __percpu *rtp)
 187 {
 188         int cpu;
 189
 190         if (!rtp)
 191                 return;
 192
 193         for_each_possible_cpu(cpu) {
 194                 struct rtable *rt;
 195
 196                 rt = rcu_dereference_protected(*per_cpu_ptr(rtp, cpu), 1);
 197                 if (rt)
 198                         dst_free(&rt->dst);
 199         }
 200         free_percpu(rtp);
 201 }
 202
 203 /* Release a nexthop info record */
 204 static void free_fib_info_rcu(struct rcu_head *head)
 205 {
 206         struct fib_info *fi = container_of(head, struct fib_info, rcu);
 207
 208         change_nexthops(fi) {
 209                 if (nexthop_nh->nh_dev)
 210                         dev_put(nexthop_nh->nh_dev);
 211                 lwtstate_put(nexthop_nh->nh_lwtstate);
 212                 free_nh_exceptions(nexthop_nh);
 213                 rt_fibinfo_free_cpus(nexthop_nh->nh_pcpu_rth_output);
 214                 rt_fibinfo_free(&nexthop_nh->nh_rth_input);
 215         } endfor_nexthops(fi);
 216
 217         if (fi->fib_metrics != (u32 *) dst_default_metrics)
 218                 kfree(fi->fib_metrics);
 219         kfree(fi);
 220 }
 221
 222 void free_fib_info(struct fib_info *fi)
 223 {
 224         if (fi->fib_dead == 0) {
 225                 pr_warn("Freeing alive fib_info %p\n", fi);
 226                 return;
 227         }
 228         fib_info_cnt--;
 229 #ifdef CONFIG_IP_ROUTE_CLASSID
 230         change_nexthops(fi) {
 231                 if (nexthop_nh->nh_tclassid)
 232                         fi->fib_net->ipv4.fib_num_tclassid_users--;
 233         } endfor_nexthops(fi);
 234 #endif
 235         call_rcu(&fi->rcu, free_fib_info_rcu);
 236 }
 237 EXPORT_SYMBOL_GPL(free_fib_info);
 238
 239 void fib_release_info(struct fib_info *fi)
 240 {
 241         spin_lock_bh(&fib_info_lock);
 242         if (fi && --fi->fib_treeref == 0) {
 243                 hlist_del(&fi->fib_hash);
 244                 if (fi->fib_prefsrc)
 245                         hlist_del(&fi->fib_lhash);
 246                 change_nexthops(fi) {
 247                         if (!nexthop_nh->nh_dev)
 248                                 continue;
 249                         hlist_del(&nexthop_nh->nh_hash);
 250                 } endfor_nexthops(fi)
 251                 fi->fib_dead = 1;
 252                 fib_info_put(fi);
 253         }
 254         spin_unlock_bh(&fib_info_lock);
 255 }
 256
 257 static inline int nh_comp(const struct fib_info *fi, const struct fib_info *ofi)
 258 {
 259         const struct fib_nh *onh = ofi->fib_nh;
 260
 261         for_nexthops(fi) {
 262                 if (nh->nh_oif != onh->nh_oif ||
 263                     nh->nh_gw  != onh->nh_gw ||
 264                     nh->nh_scope != onh->nh_scope ||
 265 #ifdef CONFIG_IP_ROUTE_MULTIPATH
 266                     nh->nh_weight != onh->nh_weight ||
 267 #endif
 268 #ifdef CONFIG_IP_ROUTE_CLASSID
 269                     nh->nh_tclassid != onh->nh_tclassid ||
 270 #endif
 271                     lwtunnel_cmp_encap(nh->nh_lwtstate, onh->nh_lwtstate) ||
 272                     ((nh->nh_flags ^ onh->nh_flags) & ~RTNH_COMPARE_MASK))
 273                         return -1;
 274                 onh++;
 275         } endfor_nexthops(fi);
 276         return 0;
 277 }
 278
 279 static inline unsigned int fib_devindex_hashfn(unsigned int val)
 280 {
 281         unsigned int mask = DEVINDEX_HASHSIZE - 1;
 282
 283         return (val ^
 284                 (val >> DEVINDEX_HASHBITS) ^
 285                 (val >> (DEVINDEX_HASHBITS * 2))) & mask;
 286 }
 287
 288 static inline unsigned int fib_info_hashfn(const struct fib_info *fi)
 289 {
 290         unsigned int mask = (fib_info_hash_size - 1);
 291         unsigned int val = fi->fib_nhs;
 292
 293         val ^= (fi->fib_protocol << 8) | fi->fib_scope;
 294         val ^= (__force u32)fi->fib_prefsrc;
 295         val ^= fi->fib_priority;
 296         for_nexthops(fi) {
 297                 val ^= fib_devindex_hashfn(nh->nh_oif);
 298         } endfor_nexthops(fi)
 299
 300         return (val ^ (val >> 7) ^ (val >> 12)) & mask;
 301 }
 302
 303 static struct fib_info *fib_find_info(const struct fib_info *nfi)
 304 {
 305         struct hlist_head *head;
 306         struct fib_info *fi;
 307         unsigned int hash;
 308
 309         hash = fib_info_hashfn(nfi);
 310         head = &fib_info_hash[hash];
 311
 312         hlist_for_each_entry(fi, head, fib_hash) {
 313                 if (!net_eq(fi->fib_net, nfi->fib_net))
 314                         continue;
 315                 if (fi->fib_nhs != nfi->fib_nhs)
 316                         continue;
 317                 if (nfi->fib_protocol == fi->fib_protocol &&
 318                     nfi->fib_scope == fi->fib_scope &&
 319                     nfi->fib_prefsrc == fi->fib_prefsrc &&
 320                     nfi->fib_priority == fi->fib_priority &&
 321                     nfi->fib_type == fi->fib_type &&
 322                     memcmp(nfi->fib_metrics, fi->fib_metrics,
 323                            sizeof(u32) * RTAX_MAX) == 0 &&
 324                     !((nfi->fib_flags ^ fi->fib_flags) & ~RTNH_COMPARE_MASK) &&
 325                     (nfi->fib_nhs == 0 || nh_comp(fi, nfi) == 0))
 326                         return fi;
 327         }
 328
 329         return NULL;
 330 }
 331
 332 /* Check, that the gateway is already configured.
 333  * Used only by redirect accept routine.
 334  */
 335 int ip_fib_check_default(__be32 gw, struct net_device *dev)
 336 {
 337         struct hlist_head *head;
 338         struct fib_nh *nh;
 339         unsigned int hash;
 340
 341         spin_lock(&fib_info_lock);
 342
 343         hash = fib_devindex_hashfn(dev->ifindex);
 344         head = &fib_info_devhash[hash];
 345         hlist_for_each_entry(nh, head, nh_hash) {
 346                 if (nh->nh_dev == dev &&
 347                     nh->nh_gw == gw &&
 348                     !(nh->nh_flags & RTNH_F_DEAD)) {
 349                         spin_unlock(&fib_info_lock);
 350                         return 0;
 351                 }
 352         }
 353
 354         spin_unlock(&fib_info_lock);
 355
 356         return -1;
 357 }
 358
 359 static inline size_t fib_nlmsg_size(struct fib_info *fi)
 360 {
 361         size_t payload = NLMSG_ALIGN(sizeof(struct rtmsg))
 362                          + nla_total_size(4) /* RTA_TABLE */
 363                          + nla_total_size(4) /* RTA_DST */
 364                          + nla_total_size(4) /* RTA_PRIORITY */
 365                          + nla_total_size(4) /* RTA_PREFSRC */
 366                          + nla_total_size(TCP_CA_NAME_MAX); /* RTAX_CC_ALGO */
 367
 368         /* space for nested metrics */
 369         payload += nla_total_size((RTAX_MAX * nla_total_size(4)));
 370
 371         if (fi->fib_nhs) {
 372                 size_t nh_encapsize = 0;
 373                 /* Also handles the special case fib_nhs == 1 */
 374
 375                 /* each nexthop is packed in an attribute */
 376                 size_t nhsize = nla_total_size(sizeof(struct rtnexthop));
 377
 378                 /* may contain flow and gateway attribute */
 379                 nhsize += 2 * nla_total_size(4);
 380
 381                 /* grab encap info */
 382                 for_nexthops(fi) {
 383                         if (nh->nh_lwtstate) {
 384                                 /* RTA_ENCAP_TYPE */
 385                                 nh_encapsize += lwtunnel_get_encap_size(
 386                                                 nh->nh_lwtstate);
 387                                 /* RTA_ENCAP */
 388                                 nh_encapsize +=  nla_total_size(2);
 389                         }
 390                 } endfor_nexthops(fi);
 391
 392                 /* all nexthops are packed in a nested attribute */
 393                 payload += nla_total_size((fi->fib_nhs * nhsize) +
 394                                           nh_encapsize);
 395
 396         }
 397
 398         return payload;
 399 }
 400
 401 void rtmsg_fib(int event, __be32 key, struct fib_alias *fa,
 402                int dst_len, u32 tb_id, const struct nl_info *info,
 403                unsigned int nlm_flags)
 404 {
 405         struct sk_buff *skb;
 406         u32 seq = info->nlh ? info->nlh->nlmsg_seq : 0;
 407         int err = -ENOBUFS;
 408
 409         skb = nlmsg_new(fib_nlmsg_size(fa->fa_info), GFP_KERNEL);
 410         if (!skb)
 411                 goto errout;
 412
 413         err = fib_dump_info(skb, info->portid, seq, event, tb_id,
 414                             fa->fa_type, key, dst_len,
 415                             fa->fa_tos, fa->fa_info, nlm_flags);
 416         if (err < 0) {
 417                 /* -EMSGSIZE implies BUG in fib_nlmsg_size() */
 418                 WARN_ON(err == -EMSGSIZE);
 419                 kfree_skb(skb);
 420                 goto errout;
 421         }
 422         rtnl_notify(skb, info->nl_net, info->portid, RTNLGRP_IPV4_ROUTE,
 423                     info->nlh, GFP_KERNEL);
 424         return;
 425 errout:
 426         if (err < 0)
 427                 rtnl_set_sk_err(info->nl_net, RTNLGRP_IPV4_ROUTE, err);
 428 }
 429
 430 static int fib_detect_death(struct fib_info *fi, int order,
 431                             struct fib_info **last_resort, int *last_idx,
 432                             int dflt)
 433 {
 434         struct neighbour *n;
 435         int state = NUD_NONE;
 436
 437         n = neigh_lookup(&arp_tbl, &fi->fib_nh[0].nh_gw, fi->fib_dev);
 438         if (n) {
 439                 state = n->nud_state;
 440                 neigh_release(n);
 441         } else {
 442                 return 0;
 443         }
 444         if (state == NUD_REACHABLE)
 445                 return 0;
 446         if ((state & NUD_VALID) && order != dflt)
 447                 return 0;
 448         if ((state & NUD_VALID) ||
 449             (*last_idx < 0 && order > dflt && state != NUD_INCOMPLETE)) {
 450                 *last_resort = fi;
 451                 *last_idx = order;
 452         }
 453         return 1;
 454 }
 455
 456 #ifdef CONFIG_IP_ROUTE_MULTIPATH
 457
 458 static int fib_count_nexthops(struct rtnexthop *rtnh, int remaining)
 459 {
 460         int nhs = 0;
 461
 462         while (rtnh_ok(rtnh, remaining)) {
 463                 nhs++;
 464                 rtnh = rtnh_next(rtnh, &remaining);
 465         }
 466
 467         /* leftover implies invalid nexthop configuration, discard it */
 468         return remaining > 0 ? 0 : nhs;
 469 }
 470
 471 static int fib_get_nhs(struct fib_info *fi, struct rtnexthop *rtnh,
 472                        int remaining, struct fib_config *cfg)
 473 {
 474         int ret;
 475
 476         change_nexthops(fi) {
 477                 int attrlen;
 478
 479                 if (!rtnh_ok(rtnh, remaining))
 480                         return -EINVAL;
 481
 482                 if (rtnh->rtnh_flags & (RTNH_F_DEAD | RTNH_F_LINKDOWN))
 483                         return -EINVAL;
 484
 485                 nexthop_nh->nh_flags =
 486                         (cfg->fc_flags & ~0xFF) | rtnh->rtnh_flags;
 487                 nexthop_nh->nh_oif = rtnh->rtnh_ifindex;
 488                 nexthop_nh->nh_weight = rtnh->rtnh_hops + 1;
 489
 490                 attrlen = rtnh_attrlen(rtnh);
 491                 if (attrlen > 0) {
 492                         struct nlattr *nla, *attrs = rtnh_attrs(rtnh);
 493
 494                         nla = nla_find(attrs, attrlen, RTA_GATEWAY);
 495                         nexthop_nh->nh_gw = nla ? nla_get_in_addr(nla) : 0;
 496 #ifdef CONFIG_IP_ROUTE_CLASSID
 497                         nla = nla_find(attrs, attrlen, RTA_FLOW);
 498                         nexthop_nh->nh_tclassid = nla ? nla_get_u32(nla) : 0;
 499                         if (nexthop_nh->nh_tclassid)
 500                                 fi->fib_net->ipv4.fib_num_tclassid_users++;
 501 #endif
 502                         nla = nla_find(attrs, attrlen, RTA_ENCAP);
 503                         if (nla) {
 504                                 struct lwtunnel_state *lwtstate;
 505                                 struct nlattr *nla_entype;
 506
 507                                 nla_entype = nla_find(attrs, attrlen,
 508                                                       RTA_ENCAP_TYPE);
 509                                 if (!nla_entype)
 510                                         goto err_inval;
 511
 512                                 ret = lwtunnel_build_state(nla_get_u16(
 513                                                            nla_entype),
 514                                                            nla,  AF_INET, cfg,
 515                                                            &lwtstate);
 516                                 if (ret)
 517                                         goto errout;
 518                                 nexthop_nh->nh_lwtstate =
 519                                         lwtstate_get(lwtstate);
 520                         }
 521                 }
 522
 523                 rtnh = rtnh_next(rtnh, &remaining);
 524         } endfor_nexthops(fi);
 525
 526         return 0;
 527
 528 err_inval:
 529         ret = -EINVAL;
 530
 531 errout:
 532         return ret;
 533 }
 534
 535 static void fib_rebalance(struct fib_info *fi)
 536 {
 537         int total;
 538         int w;
 539         struct in_device *in_dev;
 540
 541         if (fi->fib_nhs < 2)
 542                 return;
 543
 544         total = 0;
 545         for_nexthops(fi) {
 546                 if (nh->nh_flags & RTNH_F_DEAD)
 547                         continue;
 548
 549                 in_dev = __in_dev_get_rtnl(nh->nh_dev);
 550
 551                 if (in_dev &&
 552                     IN_DEV_IGNORE_ROUTES_WITH_LINKDOWN(in_dev) &&
 553                     nh->nh_flags & RTNH_F_LINKDOWN)
 554                         continue;
 555
 556                 total += nh->nh_weight;
 557         } endfor_nexthops(fi);
 558
 559         w = 0;
 560         change_nexthops(fi) {
 561                 int upper_bound;
 562
 563                 in_dev = __in_dev_get_rtnl(nexthop_nh->nh_dev);
 564
 565                 if (nexthop_nh->nh_flags & RTNH_F_DEAD) {
 566                         upper_bound = -1;
 567                 } else if (in_dev &&
 568                            IN_DEV_IGNORE_ROUTES_WITH_LINKDOWN(in_dev) &&
 569                            nexthop_nh->nh_flags & RTNH_F_LINKDOWN) {
 570                         upper_bound = -1;
 571                 } else {
 572                         w += nexthop_nh->nh_weight;
 573                         upper_bound = DIV_ROUND_CLOSEST_ULL((u64)w << 31,
 574                                                             total) - 1;
 575                 }
 576
 577                 atomic_set(&nexthop_nh->nh_upper_bound, upper_bound);
 578         } endfor_nexthops(fi);
 579
 580         net_get_random_once(&fib_multipath_secret,
 581                             sizeof(fib_multipath_secret));
 582 }
 583
 584 static inline void fib_add_weight(struct fib_info *fi,
 585                                   const struct fib_nh *nh)
 586 {
 587         fi->fib_weight += nh->nh_weight;
 588 }
 589
 590 #else /* CONFIG_IP_ROUTE_MULTIPATH */
 591
 592 #define fib_rebalance(fi) do { } while (0)
 593 #define fib_add_weight(fi, nh) do { } while (0)
 594
 595 #endif /* CONFIG_IP_ROUTE_MULTIPATH */
 596
 597 static int fib_encap_match(u16 encap_type,
 598                            struct nlattr *encap,
 599                            const struct fib_nh *nh,
 600                            const struct fib_config *cfg)
 601 {
 602         struct lwtunnel_state *lwtstate;
 603         int ret, result = 0;
 604
 605         if (encap_type == LWTUNNEL_ENCAP_NONE)
 606                 return 0;
 607
 608         ret = lwtunnel_build_state(encap_type, encap,
 609                                    AF_INET, cfg, &lwtstate);
 610         if (!ret) {
 611                 result = lwtunnel_cmp_encap(lwtstate, nh->nh_lwtstate);
 612                 lwtstate_free(lwtstate);
 613         }
 614
 615         return result;
 616 }
 617
 618 int fib_nh_match(struct fib_config *cfg, struct fib_info *fi)
 619 {
 620 #ifdef CONFIG_IP_ROUTE_MULTIPATH
 621         struct rtnexthop *rtnh;
 622         int remaining;
 623 #endif
 624
 625         if (cfg->fc_priority && cfg->fc_priority != fi->fib_priority)
 626                 return 1;
 627
 628         if (cfg->fc_oif || cfg->fc_gw) {
 629                 if (cfg->fc_encap) {
 630                         if (fib_encap_match(cfg->fc_encap_type,
 631                                             cfg->fc_encap, fi->fib_nh, cfg))
 632                             return 1;
 633                 }
 634                 if ((!cfg->fc_oif || cfg->fc_oif == fi->fib_nh->nh_oif) &&
 635                     (!cfg->fc_gw  || cfg->fc_gw == fi->fib_nh->nh_gw))
 636                         return 0;
 637                 return 1;
 638         }
 639
 640 #ifdef CONFIG_IP_ROUTE_MULTIPATH
 641         if (!cfg->fc_mp)
 642                 return 0;
 643
 644         rtnh = cfg->fc_mp;
 645         remaining = cfg->fc_mp_len;
 646
 647         for_nexthops(fi) {
 648                 int attrlen;
 649
 650                 if (!rtnh_ok(rtnh, remaining))
 651                         return -EINVAL;
 652
 653                 if (rtnh->rtnh_ifindex && rtnh->rtnh_ifindex != nh->nh_oif)
 654                         return 1;
 655
 656                 attrlen = rtnh_attrlen(rtnh);
 657                 if (attrlen > 0) {
 658                         struct nlattr *nla, *attrs = rtnh_attrs(rtnh);
 659
 660                         nla = nla_find(attrs, attrlen, RTA_GATEWAY);
 661                         if (nla && nla_get_in_addr(nla) != nh->nh_gw)
 662                                 return 1;
 663 #ifdef CONFIG_IP_ROUTE_CLASSID
 664                         nla = nla_find(attrs, attrlen, RTA_FLOW);
 665                         if (nla && nla_get_u32(nla) != nh->nh_tclassid)
 666                                 return 1;
 667 #endif
 668                 }
 669
 670                 rtnh = rtnh_next(rtnh, &remaining);
 671         } endfor_nexthops(fi);
 672 #endif
 673         return 0;
 674 }
 675
 676
 677 /*
 678  * Picture
 679  * -------
 680  *
 681  * Semantics of nexthop is very messy by historical reasons.
 682  * We have to take into account, that:
 683  * a) gateway can be actually local interface address,
 684  *    so that gatewayed route is direct.
 685  * b) gateway must be on-link address, possibly
 686  *    described not by an ifaddr, but also by a direct route.
 687  * c) If both gateway and interface are specified, they should not
 688  *    contradict.
 689  * d) If we use tunnel routes, gateway could be not on-link.
 690  *
 691  * Attempt to reconcile all of these (alas, self-contradictory) conditions
 692  * results in pretty ugly and hairy code with obscure logic.
 693  *
 694  * I chose to generalized it instead, so that the size
 695  * of code does not increase practically, but it becomes
 696  * much more general.
 697  * Every prefix is assigned a "scope" value: "host" is local address,
 698  * "link" is direct route,
 699  * [ ... "site" ... "interior" ... ]
 700  * and "universe" is true gateway route with global meaning.
 701  *
 702  * Every prefix refers to a set of "nexthop"s (gw, oif),
 703  * where gw must have narrower scope. This recursion stops
 704  * when gw has LOCAL scope or if "nexthop" is declared ONLINK,
 705  * which means that gw is forced to be on link.
 706  *
 707  * Code is still hairy, but now it is apparently logically
 708  * consistent and very flexible. F.e. as by-product it allows
 709  * to co-exists in peace independent exterior and interior
 710  * routing processes.
 711  *
 712  * Normally it looks as following.
 713  *
 714  * {universe prefix}  -> (gw, oif) [scope link]
 715  *                |
 716  *                |-> {link prefix} -> (gw, oif) [scope local]
 717  *                                      |
 718  *                                      |-> {local prefix} (terminal node)
 719  */
 720 static int fib_check_nh(struct fib_config *cfg, struct fib_info *fi,
 721                         struct fib_nh *nh)
 722 {
 723         int err = 0;
 724         struct net *net;
 725         struct net_device *dev;
 726
 727         net = cfg->fc_nlinfo.nl_net;
 728         if (nh->nh_gw) {
 729                 struct fib_result res;
 730
 731                 if (nh->nh_flags & RTNH_F_ONLINK) {
 732                         unsigned int addr_type;
 733
 734                         if (cfg->fc_scope >= RT_SCOPE_LINK)
 735                                 return -EINVAL;
 736                         dev = __dev_get_by_index(net, nh->nh_oif);
 737                         if (!dev)
 738                                 return -ENODEV;
 739                         if (!(dev->flags & IFF_UP))
 740                                 return -ENETDOWN;
 741                         addr_type = inet_addr_type_dev_table(net, dev, nh->nh_gw);
 742                         if (addr_type != RTN_UNICAST)
 743                                 return -EINVAL;
 744                         if (!netif_carrier_ok(dev))
 745                                 nh->nh_flags |= RTNH_F_LINKDOWN;
 746                         nh->nh_dev = dev;
 747                         dev_hold(dev);
 748                         nh->nh_scope = RT_SCOPE_LINK;
 749                         return 0;
 750                 }
 751                 rcu_read_lock();
 752                 {
 753                         struct fib_table *tbl = NULL;
 754                         struct flowi4 fl4 = {
 755                                 .daddr = nh->nh_gw,
 756                                 .flowi4_scope = cfg->fc_scope + 1,
 757                                 .flowi4_oif = nh->nh_oif,
 758                                 .flowi4_iif = LOOPBACK_IFINDEX,
 759                         };
 760
 761                         /* It is not necessary, but requires a bit of thinking */
 762                         if (fl4.flowi4_scope < RT_SCOPE_LINK)
 763                                 fl4.flowi4_scope = RT_SCOPE_LINK;
 764
 765                         if (cfg->fc_table)
 766                                 tbl = fib_get_table(net, cfg->fc_table);
 767
 768                         if (tbl)
 769                                 err = fib_table_lookup(tbl, &fl4, &res,
 770                                                        FIB_LOOKUP_IGNORE_LINKSTATE |
 771                                                        FIB_LOOKUP_NOREF);
 772
 773                         /* on error or if no table given do full lookup. This
 774                          * is needed for example when nexthops are in the local
 775                          * table rather than the given table
 776                          */
 777                         if (!tbl || err) {
 778                                 err = fib_lookup(net, &fl4, &res,
 779                                                  FIB_LOOKUP_IGNORE_LINKSTATE);
 780                         }
 781
 782                         if (err) {
 783                                 rcu_read_unlock();
 784                                 return err;
 785                         }
 786                 }
 787                 err = -EINVAL;
 788                 if (res.type != RTN_UNICAST && res.type != RTN_LOCAL)
 789                         goto out;
 790                 nh->nh_scope = res.scope;
 791                 nh->nh_oif = FIB_RES_OIF(res);
 792                 nh->nh_dev = dev = FIB_RES_DEV(res);
 793                 if (!dev)
 794                         goto out;
 795                 dev_hold(dev);
 796                 if (!netif_carrier_ok(dev))
 797                         nh->nh_flags |= RTNH_F_LINKDOWN;
 798                 err = (dev->flags & IFF_UP) ? 0 : -ENETDOWN;
 799         } else {
 800                 struct in_device *in_dev;
 801
 802                 if (nh->nh_flags & (RTNH_F_PERVASIVE | RTNH_F_ONLINK))
 803                         return -EINVAL;
 804
 805                 rcu_read_lock();
 806                 err = -ENODEV;
 807                 in_dev = inetdev_by_index(net, nh->nh_oif);
 808                 if (!in_dev)
 809                         goto out;
 810                 err = -ENETDOWN;
 811                 if (!(in_dev->dev->flags & IFF_UP))
 812                         goto out;
 813                 nh->nh_dev = in_dev->dev;
 814                 dev_hold(nh->nh_dev);
 815                 nh->nh_scope = RT_SCOPE_HOST;
 816                 if (!netif_carrier_ok(nh->nh_dev))
 817                         nh->nh_flags |= RTNH_F_LINKDOWN;
 818                 err = 0;
 819         }
 820 out:
 821         rcu_read_unlock();
 822         return err;
 823 }
 824
 825 static inline unsigned int fib_laddr_hashfn(__be32 val)
 826 {
 827         unsigned int mask = (fib_info_hash_size - 1);
 828
 829         return ((__force u32)val ^
 830                 ((__force u32)val >> 7) ^
 831                 ((__force u32)val >> 14)) & mask;
 832 }
 833
 834 static struct hlist_head *fib_info_hash_alloc(int bytes)
 835 {
 836         if (bytes <= PAGE_SIZE)
 837                 return kzalloc(bytes, GFP_KERNEL);
 838         else
 839                 return (struct hlist_head *)
 840                         __get_free_pages(GFP_KERNEL | __GFP_ZERO,
 841                                          get_order(bytes));
 842 }
 843
 844 static void fib_info_hash_free(struct hlist_head *hash, int bytes)
 845 {
 846         if (!hash)
 847                 return;
 848
 849         if (bytes <= PAGE_SIZE)
 850                 kfree(hash);
 851         else
 852                 free_pages((unsigned long) hash, get_order(bytes));
 853 }
 854
 855 static void fib_info_hash_move(struct hlist_head *new_info_hash,
 856                                struct hlist_head *new_laddrhash,
 857                                unsigned int new_size)
 858 {
 859         struct hlist_head *old_info_hash, *old_laddrhash;
 860         unsigned int old_size = fib_info_hash_size;
 861         unsigned int i, bytes;
 862
 863         spin_lock_bh(&fib_info_lock);
 864         old_info_hash = fib_info_hash;
 865         old_laddrhash = fib_info_laddrhash;
 866         fib_info_hash_size = new_size;
 867
 868         for (i = 0; i < old_size; i++) {
 869                 struct hlist_head *head = &fib_info_hash[i];
 870                 struct hlist_node *n;
 871                 struct fib_info *fi;
 872
 873                 hlist_for_each_entry_safe(fi, n, head, fib_hash) {
 874                         struct hlist_head *dest;
 875                         unsigned int new_hash;
 876
 877                         new_hash = fib_info_hashfn(fi);
 878                         dest = &new_info_hash[new_hash];
 879                         hlist_add_head(&fi->fib_hash, dest);
 880                 }
 881         }
 882         fib_info_hash = new_info_hash;
 883
 884         for (i = 0; i < old_size; i++) {
 885                 struct hlist_head *lhead = &fib_info_laddrhash[i];
 886                 struct hlist_node *n;
 887                 struct fib_info *fi;
 888
 889                 hlist_for_each_entry_safe(fi, n, lhead, fib_lhash) {
 890                         struct hlist_head *ldest;
 891                         unsigned int new_hash;
 892
 893                         new_hash = fib_laddr_hashfn(fi->fib_prefsrc);
 894                         ldest = &new_laddrhash[new_hash];
 895                         hlist_add_head(&fi->fib_lhash, ldest);
 896                 }
 897         }
 898         fib_info_laddrhash = new_laddrhash;
 899
 900         spin_unlock_bh(&fib_info_lock);
 901
 902         bytes = old_size * sizeof(struct hlist_head *);
 903         fib_info_hash_free(old_info_hash, bytes);
 904         fib_info_hash_free(old_laddrhash, bytes);
 905 }
 906
 907 __be32 fib_info_update_nh_saddr(struct net *net, struct fib_nh *nh)
 908 {
 909         nh->nh_saddr = inet_select_addr(nh->nh_dev,
 910                                         nh->nh_gw,
 911                                         nh->nh_parent->fib_scope);
 912         nh->nh_saddr_genid = atomic_read(&net->ipv4.dev_addr_genid);
 913
 914         return nh->nh_saddr;
 915 }
 916
 917 static bool fib_valid_prefsrc(struct fib_config *cfg, __be32 fib_prefsrc)
 918 {
 919         if (cfg->fc_type != RTN_LOCAL || !cfg->fc_dst ||
 920             fib_prefsrc != cfg->fc_dst) {
 921                 u32 tb_id = cfg->fc_table;
 922                 int rc;
 923
 924                 if (tb_id == RT_TABLE_MAIN)
 925                         tb_id = RT_TABLE_LOCAL;
 926
 927                 rc = inet_addr_type_table(cfg->fc_nlinfo.nl_net,
 928                                           fib_prefsrc, tb_id);
 929
 930                 if (rc != RTN_LOCAL && tb_id != RT_TABLE_LOCAL) {
 931                         rc = inet_addr_type_table(cfg->fc_nlinfo.nl_net,
 932                                                   fib_prefsrc, RT_TABLE_LOCAL);
 933                 }
 934
 935                 if (rc != RTN_LOCAL)
 936                         return false;
 937         }
 938         return true;
 939 }
 940
 941 static int
 942 fib_convert_metrics(struct fib_info *fi, const struct fib_config *cfg)
 943 {
 944         bool ecn_ca = false;
 945         struct nlattr *nla;
 946         int remaining;
 947
 948         if (!cfg->fc_mx)
 949                 return 0;
 950
 951         nla_for_each_attr(nla, cfg->fc_mx, cfg->fc_mx_len, remaining) {
 952                 int type = nla_type(nla);
 953                 u32 val;
 954
 955                 if (!type)
 956                         continue;
 957                 if (type > RTAX_MAX)
 958                         return -EINVAL;
 959
 960                 if (type == RTAX_CC_ALGO) {
 961                         char tmp[TCP_CA_NAME_MAX];
 962
 963                         nla_strlcpy(tmp, nla, sizeof(tmp));
 964                         val = tcp_ca_get_key_by_name(tmp, &ecn_ca);
 965                         if (val == TCP_CA_UNSPEC)
 966                                 return -EINVAL;
 967                 } else {
 968                         val = nla_get_u32(nla);
 969                 }
 970                 if (type == RTAX_ADVMSS && val > 65535 - 40)
 971                         val = 65535 - 40;
 972                 if (type == RTAX_MTU && val > 65535 - 15)
 973                         val = 65535 - 15;
 974                 if (type == RTAX_HOPLIMIT && val > 255)
 975                         val = 255;
 976                 if (type == RTAX_FEATURES && (val & ~RTAX_FEATURE_MASK))
 977                         return -EINVAL;
 978                 fi->fib_metrics[type - 1] = val;
 979         }
 980
 981         if (ecn_ca)
 982                 fi->fib_metrics[RTAX_FEATURES - 1] |= DST_FEATURE_ECN_CA;
 983
 984         return 0;
 985 }
 986
 987 struct fib_info *fib_create_info(struct fib_config *cfg)
 988 {
 989         int err;
 990         struct fib_info *fi = NULL;
 991         struct fib_info *ofi;
 992         int nhs = 1;
 993         struct net *net = cfg->fc_nlinfo.nl_net;
 994
 995         if (cfg->fc_type > RTN_MAX)
 996                 goto err_inval;
 997
 998         /* Fast check to catch the most weird cases */
 999         if (fib_props[cfg->fc_type].scope > cfg->fc_scope)
1000                 goto err_inval;
1001
1002         if (cfg->fc_flags & (RTNH_F_DEAD | RTNH_F_LINKDOWN))
1003                 goto err_inval;
1004
1005 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1006         if (cfg->fc_mp) {
1007                 nhs = fib_count_nexthops(cfg->fc_mp, cfg->fc_mp_len);
1008                 if (nhs == 0)
1009                         goto err_inval;
1010         }
1011 #endif
1012
1013         err = -ENOBUFS;
1014         if (fib_info_cnt >= fib_info_hash_size) {
1015                 unsigned int new_size = fib_info_hash_size << 1;
1016                 struct hlist_head *new_info_hash;
1017                 struct hlist_head *new_laddrhash;
1018                 unsigned int bytes;
1019
1020                 if (!new_size)
1021                         new_size = 16;
1022                 bytes = new_size * sizeof(struct hlist_head *);
1023                 new_info_hash = fib_info_hash_alloc(bytes);
1024                 new_laddrhash = fib_info_hash_alloc(bytes);
1025                 if (!new_info_hash || !new_laddrhash) {
1026                         fib_info_hash_free(new_info_hash, bytes);
1027                         fib_info_hash_free(new_laddrhash, bytes);
1028                 } else
1029                         fib_info_hash_move(new_info_hash, new_laddrhash, new_size);
1030
1031                 if (!fib_info_hash_size)
1032                         goto failure;
1033         }
1034
1035         fi = kzalloc(sizeof(*fi)+nhs*sizeof(struct fib_nh), GFP_KERNEL);
1036         if (!fi)
1037                 goto failure;
1038         fib_info_cnt++;
1039         if (cfg->fc_mx) {
1040                 fi->fib_metrics = kzalloc(sizeof(u32) * RTAX_MAX, GFP_KERNEL);
1041                 if (!fi->fib_metrics)
1042                         goto failure;
1043         } else
1044                 fi->fib_metrics = (u32 *) dst_default_metrics;
1045
1046         fi->fib_net = net;
1047         fi->fib_protocol = cfg->fc_protocol;
1048         fi->fib_scope = cfg->fc_scope;
1049         fi->fib_flags = cfg->fc_flags;
1050         fi->fib_priority = cfg->fc_priority;
1051         fi->fib_prefsrc = cfg->fc_prefsrc;
1052         fi->fib_type = cfg->fc_type;
1053         fi->fib_tb_id = cfg->fc_table;
1054
1055         fi->fib_nhs = nhs;
1056         change_nexthops(fi) {
1057                 nexthop_nh->nh_parent = fi;
1058                 nexthop_nh->nh_pcpu_rth_output = alloc_percpu(struct rtable __rcu *);
1059                 if (!nexthop_nh->nh_pcpu_rth_output)
1060                         goto failure;
1061         } endfor_nexthops(fi)
1062
1063         err = fib_convert_metrics(fi, cfg);
1064         if (err)
1065                 goto failure;
1066
1067         if (cfg->fc_mp) {
1068 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1069                 err = fib_get_nhs(fi, cfg->fc_mp, cfg->fc_mp_len, cfg);
1070                 if (err != 0)
1071                         goto failure;
1072                 if (cfg->fc_oif && fi->fib_nh->nh_oif != cfg->fc_oif)
1073                         goto err_inval;
1074                 if (cfg->fc_gw && fi->fib_nh->nh_gw != cfg->fc_gw)
1075                         goto err_inval;
1076 #ifdef CONFIG_IP_ROUTE_CLASSID
1077                 if (cfg->fc_flow && fi->fib_nh->nh_tclassid != cfg->fc_flow)
1078                         goto err_inval;
1079 #endif
1080 #else
1081                 goto err_inval;
1082 #endif
1083         } else {
1084                 struct fib_nh *nh = fi->fib_nh;
1085
1086                 if (cfg->fc_encap) {
1087                         struct lwtunnel_state *lwtstate;
1088
1089                         if (cfg->fc_encap_type == LWTUNNEL_ENCAP_NONE)
1090                                 goto err_inval;
1091                         err = lwtunnel_build_state(cfg->fc_encap_type,
1092                                                    cfg->fc_encap, AF_INET, cfg,
1093                                                    &lwtstate);
1094                         if (err)
1095                                 goto failure;
1096
1097                         nh->nh_lwtstate = lwtstate_get(lwtstate);
1098                 }
1099                 nh->nh_oif = cfg->fc_oif;
1100                 nh->nh_gw = cfg->fc_gw;
1101                 nh->nh_flags = cfg->fc_flags;
1102 #ifdef CONFIG_IP_ROUTE_CLASSID
1103                 nh->nh_tclassid = cfg->fc_flow;
1104                 if (nh->nh_tclassid)
1105                         fi->fib_net->ipv4.fib_num_tclassid_users++;
1106 #endif
1107 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1108                 nh->nh_weight = 1;
1109 #endif
1110         }
1111
1112         if (fib_props[cfg->fc_type].error) {
1113                 if (cfg->fc_gw || cfg->fc_oif || cfg->fc_mp)
1114                         goto err_inval;
1115                 goto link_it;
1116         } else {
1117                 switch (cfg->fc_type) {
1118                 case RTN_UNICAST:
1119                 case RTN_LOCAL:
1120                 case RTN_BROADCAST:
1121                 case RTN_ANYCAST:
1122                 case RTN_MULTICAST:
1123                         break;
1124                 default:
1125                         goto err_inval;
1126                 }
1127         }
1128
1129         if (cfg->fc_scope > RT_SCOPE_HOST)
1130                 goto err_inval;
1131
1132         if (cfg->fc_scope == RT_SCOPE_HOST) {
1133                 struct fib_nh *nh = fi->fib_nh;
1134
1135                 /* Local address is added. */
1136                 if (nhs != 1 || nh->nh_gw)
1137                         goto err_inval;
1138                 nh->nh_scope = RT_SCOPE_NOWHERE;
1139                 nh->nh_dev = dev_get_by_index(net, fi->fib_nh->nh_oif);
1140                 err = -ENODEV;
1141                 if (!nh->nh_dev)
1142                         goto failure;
1143         } else {
1144                 int linkdown = 0;
1145
1146                 change_nexthops(fi) {
1147                         err = fib_check_nh(cfg, fi, nexthop_nh);
1148                         if (err != 0)
1149                                 goto failure;
1150                         if (nexthop_nh->nh_flags & RTNH_F_LINKDOWN)
1151                                 linkdown++;
1152                 } endfor_nexthops(fi)
1153                 if (linkdown == fi->fib_nhs)
1154                         fi->fib_flags |= RTNH_F_LINKDOWN;
1155         }
1156
1157         if (fi->fib_prefsrc && !fib_valid_prefsrc(cfg, fi->fib_prefsrc))
1158                 goto err_inval;
1159
1160         change_nexthops(fi) {
1161                 fib_info_update_nh_saddr(net, nexthop_nh);
1162                 fib_add_weight(fi, nexthop_nh);
1163         } endfor_nexthops(fi)
1164
1165         fib_rebalance(fi);
1166
1167 link_it:
1168         ofi = fib_find_info(fi);
1169         if (ofi) {
1170                 fi->fib_dead = 1;
1171                 free_fib_info(fi);
1172                 ofi->fib_treeref++;
1173                 return ofi;
1174         }
1175
1176         fi->fib_treeref++;
1177         atomic_inc(&fi->fib_clntref);
1178         spin_lock_bh(&fib_info_lock);
1179         hlist_add_head(&fi->fib_hash,
1180                        &fib_info_hash[fib_info_hashfn(fi)]);
1181         if (fi->fib_prefsrc) {
1182                 struct hlist_head *head;
1183
1184                 head = &fib_info_laddrhash[fib_laddr_hashfn(fi->fib_prefsrc)];
1185                 hlist_add_head(&fi->fib_lhash, head);
1186         }
1187         change_nexthops(fi) {
1188                 struct hlist_head *head;
1189                 unsigned int hash;
1190
1191                 if (!nexthop_nh->nh_dev)
1192                         continue;
1193                 hash = fib_devindex_hashfn(nexthop_nh->nh_dev->ifindex);
1194                 head = &fib_info_devhash[hash];
1195                 hlist_add_head(&nexthop_nh->nh_hash, head);
1196         } endfor_nexthops(fi)
1197         spin_unlock_bh(&fib_info_lock);
1198         return fi;
1199
1200 err_inval:
1201         err = -EINVAL;
1202
1203 failure:
1204         if (fi) {
1205                 fi->fib_dead = 1;
1206                 free_fib_info(fi);
1207         }
1208
1209         return ERR_PTR(err);
1210 }
1211
1212 int fib_dump_info(struct sk_buff *skb, u32 portid, u32 seq, int event,
1213                   u32 tb_id, u8 type, __be32 dst, int dst_len, u8 tos,
1214                   struct fib_info *fi, unsigned int flags)
1215 {
1216         struct nlmsghdr *nlh;
1217         struct rtmsg *rtm;
1218
1219         nlh = nlmsg_put(skb, portid, seq, event, sizeof(*rtm), flags);
1220         if (!nlh)
1221                 return -EMSGSIZE;
1222
1223         rtm = nlmsg_data(nlh);
1224         rtm->rtm_family = AF_INET;
1225         rtm->rtm_dst_len = dst_len;
1226         rtm->rtm_src_len = 0;
1227         rtm->rtm_tos = tos;
1228         if (tb_id < 256)
1229                 rtm->rtm_table = tb_id;
1230         else
1231                 rtm->rtm_table = RT_TABLE_COMPAT;
1232         if (nla_put_u32(skb, RTA_TABLE, tb_id))
1233                 goto nla_put_failure;
1234         rtm->rtm_type = type;
1235         rtm->rtm_flags = fi->fib_flags;
1236         rtm->rtm_scope = fi->fib_scope;
1237         rtm->rtm_protocol = fi->fib_protocol;
1238
1239         if (rtm->rtm_dst_len &&
1240             nla_put_in_addr(skb, RTA_DST, dst))
1241                 goto nla_put_failure;
1242         if (fi->fib_priority &&
1243             nla_put_u32(skb, RTA_PRIORITY, fi->fib_priority))
1244                 goto nla_put_failure;
1245         if (rtnetlink_put_metrics(skb, fi->fib_metrics) < 0)
1246                 goto nla_put_failure;
1247
1248         if (fi->fib_prefsrc &&
1249             nla_put_in_addr(skb, RTA_PREFSRC, fi->fib_prefsrc))
1250                 goto nla_put_failure;
1251         if (fi->fib_nhs == 1) {
1252                 struct in_device *in_dev;
1253
1254                 if (fi->fib_nh->nh_gw &&
1255                     nla_put_in_addr(skb, RTA_GATEWAY, fi->fib_nh->nh_gw))
1256                         goto nla_put_failure;
1257                 if (fi->fib_nh->nh_oif &&
1258                     nla_put_u32(skb, RTA_OIF, fi->fib_nh->nh_oif))
1259                         goto nla_put_failure;
1260                 if (fi->fib_nh->nh_flags & RTNH_F_LINKDOWN) {
1261                         in_dev = __in_dev_get_rtnl(fi->fib_nh->nh_dev);
1262                         if (in_dev &&
1263                             IN_DEV_IGNORE_ROUTES_WITH_LINKDOWN(in_dev))
1264                                 rtm->rtm_flags |= RTNH_F_DEAD;
1265                 }
1266 #ifdef CONFIG_IP_ROUTE_CLASSID
1267                 if (fi->fib_nh[0].nh_tclassid &&
1268                     nla_put_u32(skb, RTA_FLOW, fi->fib_nh[0].nh_tclassid))
1269                         goto nla_put_failure;
1270 #endif
1271                 if (fi->fib_nh->nh_lwtstate &&
1272                     lwtunnel_fill_encap(skb, fi->fib_nh->nh_lwtstate) < 0)
1273                         goto nla_put_failure;
1274         }
1275 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1276         if (fi->fib_nhs > 1) {
1277                 struct rtnexthop *rtnh;
1278                 struct nlattr *mp;
1279
1280                 mp = nla_nest_start(skb, RTA_MULTIPATH);
1281                 if (!mp)
1282                         goto nla_put_failure;
1283
1284                 for_nexthops(fi) {
1285                         struct in_device *in_dev;
1286
1287                         rtnh = nla_reserve_nohdr(skb, sizeof(*rtnh));
1288                         if (!rtnh)
1289                                 goto nla_put_failure;
1290
1291                         rtnh->rtnh_flags = nh->nh_flags & 0xFF;
1292                         if (nh->nh_flags & RTNH_F_LINKDOWN) {
1293                                 in_dev = __in_dev_get_rtnl(nh->nh_dev);
1294                                 if (in_dev &&
1295                                     IN_DEV_IGNORE_ROUTES_WITH_LINKDOWN(in_dev))
1296                                         rtnh->rtnh_flags |= RTNH_F_DEAD;
1297                         }
1298                         rtnh->rtnh_hops = nh->nh_weight - 1;
1299                         rtnh->rtnh_ifindex = nh->nh_oif;
1300
1301                         if (nh->nh_gw &&
1302                             nla_put_in_addr(skb, RTA_GATEWAY, nh->nh_gw))
1303                                 goto nla_put_failure;
1304 #ifdef CONFIG_IP_ROUTE_CLASSID
1305                         if (nh->nh_tclassid &&
1306                             nla_put_u32(skb, RTA_FLOW, nh->nh_tclassid))
1307                                 goto nla_put_failure;
1308 #endif
1309                         if (nh->nh_lwtstate &&
1310                             lwtunnel_fill_encap(skb, nh->nh_lwtstate) < 0)
1311                                 goto nla_put_failure;
1312
1313                         /* length of rtnetlink header + attributes */
1314                         rtnh->rtnh_len = nlmsg_get_pos(skb) - (void *) rtnh;
1315                 } endfor_nexthops(fi);
1316
1317                 nla_nest_end(skb, mp);
1318         }
1319 #endif
1320         nlmsg_end(skb, nlh);
1321         return 0;
1322
1323 nla_put_failure:
1324         nlmsg_cancel(skb, nlh);
1325         return -EMSGSIZE;
1326 }
1327
1328 /*
1329  * Update FIB if:
1330  * - local address disappeared -> we must delete all the entries
1331  *   referring to it.
1332  * - device went down -> we must shutdown all nexthops going via it.
1333  */
1334 int fib_sync_down_addr(struct net_device *dev, __be32 local)
1335 {
1336         int ret = 0;
1337         unsigned int hash = fib_laddr_hashfn(local);
1338         struct hlist_head *head = &fib_info_laddrhash[hash];
1339         struct net *net = dev_net(dev);
1340         int tb_id = l3mdev_fib_table(dev);
1341         struct fib_info *fi;
1342
1343         if (!fib_info_laddrhash || local == 0)
1344                 return 0;
1345
1346         hlist_for_each_entry(fi, head, fib_lhash) {
1347                 if (!net_eq(fi->fib_net, net) ||
1348                     fi->fib_tb_id != tb_id)
1349                         continue;
1350                 if (fi->fib_prefsrc == local) {
1351                         fi->fib_flags |= RTNH_F_DEAD;
1352                         ret++;
1353                 }
1354         }
1355         return ret;
1356 }
1357
1358 static int call_fib_nh_notifiers(struct fib_nh *fib_nh,
1359                                  enum fib_event_type event_type)
1360 {
1361         struct in_device *in_dev = __in_dev_get_rtnl(fib_nh->nh_dev);
1362         struct fib_nh_notifier_info info = {
1363                 .fib_nh = fib_nh,
1364         };
1365
1366         switch (event_type) {
1367         case FIB_EVENT_NH_ADD:
1368                 if (fib_nh->nh_flags & RTNH_F_DEAD)
1369                         break;
1370                 if (IN_DEV_IGNORE_ROUTES_WITH_LINKDOWN(in_dev) &&
1371                     fib_nh->nh_flags & RTNH_F_LINKDOWN)
1372                         break;
1373                 return call_fib_notifiers(dev_net(fib_nh->nh_dev), event_type,
1374                                           &info.info);
1375         case FIB_EVENT_NH_DEL:
1376                 if ((IN_DEV_IGNORE_ROUTES_WITH_LINKDOWN(in_dev) &&
1377                      fib_nh->nh_flags & RTNH_F_LINKDOWN) ||
1378                     (fib_nh->nh_flags & RTNH_F_DEAD))
1379                         return call_fib_notifiers(dev_net(fib_nh->nh_dev),
1380                                                   event_type, &info.info);
1381         default:
1382                 break;
1383         }
1384
1385         return NOTIFY_DONE;
1386 }
1387
1388 /* Event              force Flags           Description
1389  * NETDEV_CHANGE      0     LINKDOWN        Carrier OFF, not for scope host
1390  * NETDEV_DOWN        0     LINKDOWN|DEAD   Link down, not for scope host
1391  * NETDEV_DOWN        1     LINKDOWN|DEAD   Last address removed
1392  * NETDEV_UNREGISTER  1     LINKDOWN|DEAD   Device removed
1393  */
1394 int fib_sync_down_dev(struct net_device *dev, unsigned long event, bool force)
1395 {
1396         int ret = 0;
1397         int scope = RT_SCOPE_NOWHERE;
1398         struct fib_info *prev_fi = NULL;
1399         unsigned int hash = fib_devindex_hashfn(dev->ifindex);
1400         struct hlist_head *head = &fib_info_devhash[hash];
1401         struct fib_nh *nh;
1402
1403         if (force)
1404                 scope = -1;
1405
1406         hlist_for_each_entry(nh, head, nh_hash) {
1407                 struct fib_info *fi = nh->nh_parent;
1408                 int dead;
1409
1410                 BUG_ON(!fi->fib_nhs);
1411                 if (nh->nh_dev != dev || fi == prev_fi)
1412                         continue;
1413                 prev_fi = fi;
1414                 dead = 0;
1415                 change_nexthops(fi) {
1416                         if (nexthop_nh->nh_flags & RTNH_F_DEAD)
1417                                 dead++;
1418                         else if (nexthop_nh->nh_dev == dev &&
1419                                  nexthop_nh->nh_scope != scope) {
1420                                 switch (event) {
1421                                 case NETDEV_DOWN:
1422                                 case NETDEV_UNREGISTER:
1423                                         nexthop_nh->nh_flags |= RTNH_F_DEAD;
1424                                         /* fall through */
1425                                 case NETDEV_CHANGE:
1426                                         nexthop_nh->nh_flags |= RTNH_F_LINKDOWN;
1427                                         break;
1428                                 }
1429                                 call_fib_nh_notifiers(nexthop_nh,
1430                                                       FIB_EVENT_NH_DEL);
1431                                 dead++;
1432                         }
1433 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1434                         if (event == NETDEV_UNREGISTER &&
1435                             nexthop_nh->nh_dev == dev) {
1436                                 dead = fi->fib_nhs;
1437                                 break;
1438                         }
1439 #endif
1440                 } endfor_nexthops(fi)
1441                 if (dead == fi->fib_nhs) {
1442                         switch (event) {
1443                         case NETDEV_DOWN:
1444                         case NETDEV_UNREGISTER:
1445                                 fi->fib_flags |= RTNH_F_DEAD;
1446                                 /* fall through */
1447                         case NETDEV_CHANGE:
1448                                 fi->fib_flags |= RTNH_F_LINKDOWN;
1449                                 break;
1450                         }
1451                         ret++;
1452                 }
1453
1454                 fib_rebalance(fi);
1455         }
1456
1457         return ret;
1458 }
1459
1460 /* Must be invoked inside of an RCU protected region.  */
1461 static void fib_select_default(const struct flowi4 *flp, struct fib_result *res)
1462 {
1463         struct fib_info *fi = NULL, *last_resort = NULL;
1464         struct hlist_head *fa_head = res->fa_head;
1465         struct fib_table *tb = res->table;
1466         u8 slen = 32 - res->prefixlen;
1467         int order = -1, last_idx = -1;
1468         struct fib_alias *fa, *fa1 = NULL;
1469         u32 last_prio = res->fi->fib_priority;
1470         u8 last_tos = 0;
1471
1472         hlist_for_each_entry_rcu(fa, fa_head, fa_list) {
1473                 struct fib_info *next_fi = fa->fa_info;
1474
1475                 if (fa->fa_slen != slen)
1476                         continue;
1477                 if (fa->fa_tos && fa->fa_tos != flp->flowi4_tos)
1478                         continue;
1479                 if (fa->tb_id != tb->tb_id)
1480                         continue;
1481                 if (next_fi->fib_priority > last_prio &&
1482                     fa->fa_tos == last_tos) {
1483                         if (last_tos)
1484                                 continue;
1485                         break;
1486                 }
1487                 if (next_fi->fib_flags & RTNH_F_DEAD)
1488                         continue;
1489                 last_tos = fa->fa_tos;
1490                 last_prio = next_fi->fib_priority;
1491
1492                 if (next_fi->fib_scope != res->scope ||
1493                     fa->fa_type != RTN_UNICAST)
1494                         continue;
1495                 if (!next_fi->fib_nh[0].nh_gw ||
1496                     next_fi->fib_nh[0].nh_scope != RT_SCOPE_LINK)
1497                         continue;
1498
1499                 fib_alias_accessed(fa);
1500
1501                 if (!fi) {
1502                         if (next_fi != res->fi)
1503                                 break;
1504                         fa1 = fa;
1505                 } else if (!fib_detect_death(fi, order, &last_resort,
1506                                              &last_idx, fa1->fa_default)) {
1507                         fib_result_assign(res, fi);
1508                         fa1->fa_default = order;
1509                         goto out;
1510                 }
1511                 fi = next_fi;
1512                 order++;
1513         }
1514
1515         if (order <= 0 || !fi) {
1516                 if (fa1)
1517                         fa1->fa_default = -1;
1518                 goto out;
1519         }
1520
1521         if (!fib_detect_death(fi, order, &last_resort, &last_idx,
1522                               fa1->fa_default)) {
1523                 fib_result_assign(res, fi);
1524                 fa1->fa_default = order;
1525                 goto out;
1526         }
1527
1528         if (last_idx >= 0)
1529                 fib_result_assign(res, last_resort);
1530         fa1->fa_default = last_idx;
1531 out:
1532         return;
1533 }
1534
1535 /*
1536  * Dead device goes up. We wake up dead nexthops.
1537  * It takes sense only on multipath routes.
1538  */
1539 int fib_sync_up(struct net_device *dev, unsigned int nh_flags)
1540 {
1541         struct fib_info *prev_fi;
1542         unsigned int hash;
1543         struct hlist_head *head;
1544         struct fib_nh *nh;
1545         int ret;
1546
1547         if (!(dev->flags & IFF_UP))
1548                 return 0;
1549
1550         if (nh_flags & RTNH_F_DEAD) {
1551                 unsigned int flags = dev_get_flags(dev);
1552
1553                 if (flags & (IFF_RUNNING | IFF_LOWER_UP))
1554                         nh_flags |= RTNH_F_LINKDOWN;
1555         }
1556
1557         prev_fi = NULL;
1558         hash = fib_devindex_hashfn(dev->ifindex);
1559         head = &fib_info_devhash[hash];
1560         ret = 0;
1561
1562         hlist_for_each_entry(nh, head, nh_hash) {
1563                 struct fib_info *fi = nh->nh_parent;
1564                 int alive;
1565
1566                 BUG_ON(!fi->fib_nhs);
1567                 if (nh->nh_dev != dev || fi == prev_fi)
1568                         continue;
1569
1570                 prev_fi = fi;
1571                 alive = 0;
1572                 change_nexthops(fi) {
1573                         if (!(nexthop_nh->nh_flags & nh_flags)) {
1574                                 alive++;
1575                                 continue;
1576                         }
1577                         if (!nexthop_nh->nh_dev ||
1578                             !(nexthop_nh->nh_dev->flags & IFF_UP))
1579                                 continue;
1580                         if (nexthop_nh->nh_dev != dev ||
1581                             !__in_dev_get_rtnl(dev))
1582                                 continue;
1583                         alive++;
1584                         nexthop_nh->nh_flags &= ~nh_flags;
1585                         call_fib_nh_notifiers(nexthop_nh, FIB_EVENT_NH_ADD);
1586                 } endfor_nexthops(fi)
1587
1588                 if (alive > 0) {
1589                         fi->fib_flags &= ~nh_flags;
1590                         ret++;
1591                 }
1592
1593                 fib_rebalance(fi);
1594         }
1595
1596         return ret;
1597 }
1598
1599 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1600 static bool fib_good_nh(const struct fib_nh *nh)
1601 {
1602         int state = NUD_REACHABLE;
1603
1604         if (nh->nh_scope == RT_SCOPE_LINK) {
1605                 struct neighbour *n;
1606
1607                 rcu_read_lock_bh();
1608
1609                 n = __ipv4_neigh_lookup_noref(nh->nh_dev,
1610                                               (__force u32)nh->nh_gw);
1611                 if (n)
1612                         state = n->nud_state;
1613
1614                 rcu_read_unlock_bh();
1615         }
1616
1617         return !!(state & NUD_VALID);
1618 }
1619
1620 void fib_select_multipath(struct fib_result *res, int hash)
1621 {
1622         struct fib_info *fi = res->fi;
1623         struct net *net = fi->fib_net;
1624         bool first = false;
1625
1626         for_nexthops(fi) {
1627                 if (hash > atomic_read(&nh->nh_upper_bound))
1628                         continue;
1629
1630                 if (!net->ipv4.sysctl_fib_multipath_use_neigh ||
1631                     fib_good_nh(nh)) {
1632                         res->nh_sel = nhsel;
1633                         return;
1634                 }
1635                 if (!first) {
1636                         res->nh_sel = nhsel;
1637                         first = true;
1638                 }
1639         } endfor_nexthops(fi);
1640 }
1641 #endif
1642
1643 void fib_select_path(struct net *net, struct fib_result *res,
1644                      struct flowi4 *fl4, int mp_hash)
1645 {
1646         bool oif_check;
1647
1648         oif_check = (fl4->flowi4_oif == 0 ||
1649                      fl4->flowi4_flags & FLOWI_FLAG_SKIP_NH_OIF);
1650
1651 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1652         if (res->fi->fib_nhs > 1 && oif_check) {
1653                 if (mp_hash < 0)
1654                         mp_hash = get_hash_from_flowi4(fl4) >> 1;
1655
1656                 fib_select_multipath(res, mp_hash);
1657         }
1658         else
1659 #endif
1660         if (!res->prefixlen &&
1661             res->table->tb_num_default > 1 &&
1662             res->type == RTN_UNICAST && oif_check)
1663                 fib_select_default(fl4, res);
1664
1665         if (!fl4->saddr)
1666                 fl4->saddr = FIB_RES_PREFSRC(net, *res);
1667 }
1668 EXPORT_SYMBOL_GPL(fib_select_path);