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 <asm/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
  61 static DEFINE_SPINLOCK(fib_multipath_lock);
  62
  63 #define for_nexthops(fi) {                                              \
  64         int nhsel; const struct fib_nh *nh;                             \
  65         for (nhsel = 0, nh = (fi)->fib_nh;                              \
  66              nhsel < (fi)->fib_nhs;                                     \
  67              nh++, nhsel++)
  68
  69 #define change_nexthops(fi) {                                           \
  70         int nhsel; struct fib_nh *nexthop_nh;                           \
  71         for (nhsel = 0, nexthop_nh = (struct fib_nh *)((fi)->fib_nh);   \
  72              nhsel < (fi)->fib_nhs;                                     \
  73              nexthop_nh++, nhsel++)
  74
  75 #else /* CONFIG_IP_ROUTE_MULTIPATH */
  76
  77 /* Hope, that gcc will optimize it to get rid of dummy loop */
  78
  79 #define for_nexthops(fi) {                                              \
  80         int nhsel; const struct fib_nh *nh = (fi)->fib_nh;              \
  81         for (nhsel = 0; nhsel < 1; nhsel++)
  82
  83 #define change_nexthops(fi) {                                           \
  84         int nhsel;                                                      \
  85         struct fib_nh *nexthop_nh = (struct fib_nh *)((fi)->fib_nh);    \
  86         for (nhsel = 0; nhsel < 1; nhsel++)
  87
  88 #endif /* CONFIG_IP_ROUTE_MULTIPATH */
  89
  90 #define endfor_nexthops(fi) }
  91
  92
  93 const struct fib_prop fib_props[RTN_MAX + 1] = {
  94         [RTN_UNSPEC] = {
  95                 .error  = 0,
  96                 .scope  = RT_SCOPE_NOWHERE,
  97         },
  98         [RTN_UNICAST] = {
  99                 .error  = 0,
 100                 .scope  = RT_SCOPE_UNIVERSE,
 101         },
 102         [RTN_LOCAL] = {
 103                 .error  = 0,
 104                 .scope  = RT_SCOPE_HOST,
 105         },
 106         [RTN_BROADCAST] = {
 107                 .error  = 0,
 108                 .scope  = RT_SCOPE_LINK,
 109         },
 110         [RTN_ANYCAST] = {
 111                 .error  = 0,
 112                 .scope  = RT_SCOPE_LINK,
 113         },
 114         [RTN_MULTICAST] = {
 115                 .error  = 0,
 116                 .scope  = RT_SCOPE_UNIVERSE,
 117         },
 118         [RTN_BLACKHOLE] = {
 119                 .error  = -EINVAL,
 120                 .scope  = RT_SCOPE_UNIVERSE,
 121         },
 122         [RTN_UNREACHABLE] = {
 123                 .error  = -EHOSTUNREACH,
 124                 .scope  = RT_SCOPE_UNIVERSE,
 125         },
 126         [RTN_PROHIBIT] = {
 127                 .error  = -EACCES,
 128                 .scope  = RT_SCOPE_UNIVERSE,
 129         },
 130         [RTN_THROW] = {
 131                 .error  = -EAGAIN,
 132                 .scope  = RT_SCOPE_UNIVERSE,
 133         },
 134         [RTN_NAT] = {
 135                 .error  = -EINVAL,
 136                 .scope  = RT_SCOPE_NOWHERE,
 137         },
 138         [RTN_XRESOLVE] = {
 139                 .error  = -EINVAL,
 140                 .scope  = RT_SCOPE_NOWHERE,
 141         },
 142 };
 143
 144 static void rt_fibinfo_free(struct rtable __rcu **rtp)
 145 {
 146         struct rtable *rt = rcu_dereference_protected(*rtp, 1);
 147
 148         if (!rt)
 149                 return;
 150
 151         /* Not even needed : RCU_INIT_POINTER(*rtp, NULL);
 152          * because we waited an RCU grace period before calling
 153          * free_fib_info_rcu()
 154          */
 155
 156         dst_free(&rt->dst);
 157 }
 158
 159 static void free_nh_exceptions(struct fib_nh *nh)
 160 {
 161         struct fnhe_hash_bucket *hash;
 162         int i;
 163
 164         hash = rcu_dereference_protected(nh->nh_exceptions, 1);
 165         if (!hash)
 166                 return;
 167         for (i = 0; i < FNHE_HASH_SIZE; i++) {
 168                 struct fib_nh_exception *fnhe;
 169
 170                 fnhe = rcu_dereference_protected(hash[i].chain, 1);
 171                 while (fnhe) {
 172                         struct fib_nh_exception *next;
 173
 174                         next = rcu_dereference_protected(fnhe->fnhe_next, 1);
 175
 176                         rt_fibinfo_free(&fnhe->fnhe_rth_input);
 177                         rt_fibinfo_free(&fnhe->fnhe_rth_output);
 178
 179                         kfree(fnhe);
 180
 181                         fnhe = next;
 182                 }
 183         }
 184         kfree(hash);
 185 }
 186
 187 static void rt_fibinfo_free_cpus(struct rtable __rcu * __percpu *rtp)
 188 {
 189         int cpu;
 190
 191         if (!rtp)
 192                 return;
 193
 194         for_each_possible_cpu(cpu) {
 195                 struct rtable *rt;
 196
 197                 rt = rcu_dereference_protected(*per_cpu_ptr(rtp, cpu), 1);
 198                 if (rt)
 199                         dst_free(&rt->dst);
 200         }
 201         free_percpu(rtp);
 202 }
 203
 204 /* Release a nexthop info record */
 205 static void free_fib_info_rcu(struct rcu_head *head)
 206 {
 207         struct fib_info *fi = container_of(head, struct fib_info, rcu);
 208
 209         change_nexthops(fi) {
 210                 if (nexthop_nh->nh_dev)
 211                         dev_put(nexthop_nh->nh_dev);
 212                 lwtstate_put(nexthop_nh->nh_lwtstate);
 213                 free_nh_exceptions(nexthop_nh);
 214                 rt_fibinfo_free_cpus(nexthop_nh->nh_pcpu_rth_output);
 215                 rt_fibinfo_free(&nexthop_nh->nh_rth_input);
 216         } endfor_nexthops(fi);
 217
 218         if (fi->fib_metrics != (u32 *) dst_default_metrics)
 219                 kfree(fi->fib_metrics);
 220         kfree(fi);
 221 }
 222
 223 void free_fib_info(struct fib_info *fi)
 224 {
 225         if (fi->fib_dead == 0) {
 226                 pr_warn("Freeing alive fib_info %p\n", fi);
 227                 return;
 228         }
 229         fib_info_cnt--;
 230 #ifdef CONFIG_IP_ROUTE_CLASSID
 231         change_nexthops(fi) {
 232                 if (nexthop_nh->nh_tclassid)
 233                         fi->fib_net->ipv4.fib_num_tclassid_users--;
 234         } endfor_nexthops(fi);
 235 #endif
 236         call_rcu(&fi->rcu, free_fib_info_rcu);
 237 }
 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         struct net *net = cfg->fc_nlinfo.nl_net;
 475         int ret;
 476
 477         change_nexthops(fi) {
 478                 int attrlen;
 479
 480                 if (!rtnh_ok(rtnh, remaining))
 481                         return -EINVAL;
 482
 483                 nexthop_nh->nh_flags =
 484                         (cfg->fc_flags & ~0xFF) | rtnh->rtnh_flags;
 485                 nexthop_nh->nh_oif = rtnh->rtnh_ifindex;
 486                 nexthop_nh->nh_weight = rtnh->rtnh_hops + 1;
 487
 488                 attrlen = rtnh_attrlen(rtnh);
 489                 if (attrlen > 0) {
 490                         struct nlattr *nla, *attrs = rtnh_attrs(rtnh);
 491
 492                         nla = nla_find(attrs, attrlen, RTA_GATEWAY);
 493                         nexthop_nh->nh_gw = nla ? nla_get_in_addr(nla) : 0;
 494 #ifdef CONFIG_IP_ROUTE_CLASSID
 495                         nla = nla_find(attrs, attrlen, RTA_FLOW);
 496                         nexthop_nh->nh_tclassid = nla ? nla_get_u32(nla) : 0;
 497                         if (nexthop_nh->nh_tclassid)
 498                                 fi->fib_net->ipv4.fib_num_tclassid_users++;
 499 #endif
 500                         nla = nla_find(attrs, attrlen, RTA_ENCAP);
 501                         if (nla) {
 502                                 struct lwtunnel_state *lwtstate;
 503                                 struct net_device *dev = NULL;
 504                                 struct nlattr *nla_entype;
 505
 506                                 nla_entype = nla_find(attrs, attrlen,
 507                                                       RTA_ENCAP_TYPE);
 508                                 if (!nla_entype)
 509                                         goto err_inval;
 510                                 if (cfg->fc_oif)
 511                                         dev = __dev_get_by_index(net, cfg->fc_oif);
 512                                 ret = lwtunnel_build_state(dev, 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 #endif
 536
 537 static int fib_encap_match(struct net *net, u16 encap_type,
 538                            struct nlattr *encap,
 539                            int oif, const struct fib_nh *nh,
 540                            const struct fib_config *cfg)
 541 {
 542         struct lwtunnel_state *lwtstate;
 543         struct net_device *dev = NULL;
 544         int ret, result = 0;
 545
 546         if (encap_type == LWTUNNEL_ENCAP_NONE)
 547                 return 0;
 548
 549         if (oif)
 550                 dev = __dev_get_by_index(net, oif);
 551         ret = lwtunnel_build_state(dev, encap_type, encap,
 552                                    AF_INET, cfg, &lwtstate);
 553         if (!ret) {
 554                 result = lwtunnel_cmp_encap(lwtstate, nh->nh_lwtstate);
 555                 lwtstate_free(lwtstate);
 556         }
 557
 558         return result;
 559 }
 560
 561 int fib_nh_match(struct fib_config *cfg, struct fib_info *fi)
 562 {
 563         struct net *net = cfg->fc_nlinfo.nl_net;
 564 #ifdef CONFIG_IP_ROUTE_MULTIPATH
 565         struct rtnexthop *rtnh;
 566         int remaining;
 567 #endif
 568
 569         if (cfg->fc_priority && cfg->fc_priority != fi->fib_priority)
 570                 return 1;
 571
 572         if (cfg->fc_oif || cfg->fc_gw) {
 573                 if (cfg->fc_encap) {
 574                         if (fib_encap_match(net, cfg->fc_encap_type,
 575                                             cfg->fc_encap, cfg->fc_oif,
 576                                             fi->fib_nh, cfg))
 577                             return 1;
 578                 }
 579                 if ((!cfg->fc_oif || cfg->fc_oif == fi->fib_nh->nh_oif) &&
 580                     (!cfg->fc_gw  || cfg->fc_gw == fi->fib_nh->nh_gw))
 581                         return 0;
 582                 return 1;
 583         }
 584
 585 #ifdef CONFIG_IP_ROUTE_MULTIPATH
 586         if (!cfg->fc_mp)
 587                 return 0;
 588
 589         rtnh = cfg->fc_mp;
 590         remaining = cfg->fc_mp_len;
 591
 592         for_nexthops(fi) {
 593                 int attrlen;
 594
 595                 if (!rtnh_ok(rtnh, remaining))
 596                         return -EINVAL;
 597
 598                 if (rtnh->rtnh_ifindex && rtnh->rtnh_ifindex != nh->nh_oif)
 599                         return 1;
 600
 601                 attrlen = rtnh_attrlen(rtnh);
 602                 if (attrlen > 0) {
 603                         struct nlattr *nla, *attrs = rtnh_attrs(rtnh);
 604
 605                         nla = nla_find(attrs, attrlen, RTA_GATEWAY);
 606                         if (nla && nla_get_in_addr(nla) != nh->nh_gw)
 607                                 return 1;
 608 #ifdef CONFIG_IP_ROUTE_CLASSID
 609                         nla = nla_find(attrs, attrlen, RTA_FLOW);
 610                         if (nla && nla_get_u32(nla) != nh->nh_tclassid)
 611                                 return 1;
 612 #endif
 613                 }
 614
 615                 rtnh = rtnh_next(rtnh, &remaining);
 616         } endfor_nexthops(fi);
 617 #endif
 618         return 0;
 619 }
 620
 621
 622 /*
 623  * Picture
 624  * -------
 625  *
 626  * Semantics of nexthop is very messy by historical reasons.
 627  * We have to take into account, that:
 628  * a) gateway can be actually local interface address,
 629  *    so that gatewayed route is direct.
 630  * b) gateway must be on-link address, possibly
 631  *    described not by an ifaddr, but also by a direct route.
 632  * c) If both gateway and interface are specified, they should not
 633  *    contradict.
 634  * d) If we use tunnel routes, gateway could be not on-link.
 635  *
 636  * Attempt to reconcile all of these (alas, self-contradictory) conditions
 637  * results in pretty ugly and hairy code with obscure logic.
 638  *
 639  * I chose to generalized it instead, so that the size
 640  * of code does not increase practically, but it becomes
 641  * much more general.
 642  * Every prefix is assigned a "scope" value: "host" is local address,
 643  * "link" is direct route,
 644  * [ ... "site" ... "interior" ... ]
 645  * and "universe" is true gateway route with global meaning.
 646  *
 647  * Every prefix refers to a set of "nexthop"s (gw, oif),
 648  * where gw must have narrower scope. This recursion stops
 649  * when gw has LOCAL scope or if "nexthop" is declared ONLINK,
 650  * which means that gw is forced to be on link.
 651  *
 652  * Code is still hairy, but now it is apparently logically
 653  * consistent and very flexible. F.e. as by-product it allows
 654  * to co-exists in peace independent exterior and interior
 655  * routing processes.
 656  *
 657  * Normally it looks as following.
 658  *
 659  * {universe prefix}  -> (gw, oif) [scope link]
 660  *                |
 661  *                |-> {link prefix} -> (gw, oif) [scope local]
 662  *                                      |
 663  *                                      |-> {local prefix} (terminal node)
 664  */
 665 static int fib_check_nh(struct fib_config *cfg, struct fib_info *fi,
 666                         struct fib_nh *nh)
 667 {
 668         int err = 0;
 669         struct net *net;
 670         struct net_device *dev;
 671
 672         net = cfg->fc_nlinfo.nl_net;
 673         if (nh->nh_gw) {
 674                 struct fib_result res;
 675
 676                 if (nh->nh_flags & RTNH_F_ONLINK) {
 677                         unsigned int addr_type;
 678
 679                         if (cfg->fc_scope >= RT_SCOPE_LINK)
 680                                 return -EINVAL;
 681                         dev = __dev_get_by_index(net, nh->nh_oif);
 682                         if (!dev)
 683                                 return -ENODEV;
 684                         if (!(dev->flags & IFF_UP))
 685                                 return -ENETDOWN;
 686                         addr_type = inet_addr_type_dev_table(net, dev, nh->nh_gw);
 687                         if (addr_type != RTN_UNICAST)
 688                                 return -EINVAL;
 689                         if (!netif_carrier_ok(dev))
 690                                 nh->nh_flags |= RTNH_F_LINKDOWN;
 691                         nh->nh_dev = dev;
 692                         dev_hold(dev);
 693                         nh->nh_scope = RT_SCOPE_LINK;
 694                         return 0;
 695                 }
 696                 rcu_read_lock();
 697                 {
 698                         struct fib_table *tbl = NULL;
 699                         struct flowi4 fl4 = {
 700                                 .daddr = nh->nh_gw,
 701                                 .flowi4_scope = cfg->fc_scope + 1,
 702                                 .flowi4_oif = nh->nh_oif,
 703                                 .flowi4_iif = LOOPBACK_IFINDEX,
 704                         };
 705
 706                         /* It is not necessary, but requires a bit of thinking */
 707                         if (fl4.flowi4_scope < RT_SCOPE_LINK)
 708                                 fl4.flowi4_scope = RT_SCOPE_LINK;
 709
 710                         if (cfg->fc_table)
 711                                 tbl = fib_get_table(net, cfg->fc_table);
 712
 713                         if (tbl)
 714                                 err = fib_table_lookup(tbl, &fl4, &res,
 715                                                        FIB_LOOKUP_IGNORE_LINKSTATE |
 716                                                        FIB_LOOKUP_NOREF);
 717
 718                         /* on error or if no table given do full lookup. This
 719                          * is needed for example when nexthops are in the local
 720                          * table rather than the given table
 721                          */
 722                         if (!tbl || err) {
 723                                 err = fib_lookup(net, &fl4, &res,
 724                                                  FIB_LOOKUP_IGNORE_LINKSTATE);
 725                         }
 726
 727                         if (err) {
 728                                 rcu_read_unlock();
 729                                 return err;
 730                         }
 731                 }
 732                 err = -EINVAL;
 733                 if (res.type != RTN_UNICAST && res.type != RTN_LOCAL)
 734                         goto out;
 735                 nh->nh_scope = res.scope;
 736                 nh->nh_oif = FIB_RES_OIF(res);
 737                 nh->nh_dev = dev = FIB_RES_DEV(res);
 738                 if (!dev)
 739                         goto out;
 740                 dev_hold(dev);
 741                 if (!netif_carrier_ok(dev))
 742                         nh->nh_flags |= RTNH_F_LINKDOWN;
 743                 err = (dev->flags & IFF_UP) ? 0 : -ENETDOWN;
 744         } else {
 745                 struct in_device *in_dev;
 746
 747                 if (nh->nh_flags & (RTNH_F_PERVASIVE | RTNH_F_ONLINK))
 748                         return -EINVAL;
 749
 750                 rcu_read_lock();
 751                 err = -ENODEV;
 752                 in_dev = inetdev_by_index(net, nh->nh_oif);
 753                 if (!in_dev)
 754                         goto out;
 755                 err = -ENETDOWN;
 756                 if (!(in_dev->dev->flags & IFF_UP))
 757                         goto out;
 758                 nh->nh_dev = in_dev->dev;
 759                 dev_hold(nh->nh_dev);
 760                 nh->nh_scope = RT_SCOPE_HOST;
 761                 if (!netif_carrier_ok(nh->nh_dev))
 762                         nh->nh_flags |= RTNH_F_LINKDOWN;
 763                 err = 0;
 764         }
 765 out:
 766         rcu_read_unlock();
 767         return err;
 768 }
 769
 770 static inline unsigned int fib_laddr_hashfn(__be32 val)
 771 {
 772         unsigned int mask = (fib_info_hash_size - 1);
 773
 774         return ((__force u32)val ^
 775                 ((__force u32)val >> 7) ^
 776                 ((__force u32)val >> 14)) & mask;
 777 }
 778
 779 static struct hlist_head *fib_info_hash_alloc(int bytes)
 780 {
 781         if (bytes <= PAGE_SIZE)
 782                 return kzalloc(bytes, GFP_KERNEL);
 783         else
 784                 return (struct hlist_head *)
 785                         __get_free_pages(GFP_KERNEL | __GFP_ZERO,
 786                                          get_order(bytes));
 787 }
 788
 789 static void fib_info_hash_free(struct hlist_head *hash, int bytes)
 790 {
 791         if (!hash)
 792                 return;
 793
 794         if (bytes <= PAGE_SIZE)
 795                 kfree(hash);
 796         else
 797                 free_pages((unsigned long) hash, get_order(bytes));
 798 }
 799
 800 static void fib_info_hash_move(struct hlist_head *new_info_hash,
 801                                struct hlist_head *new_laddrhash,
 802                                unsigned int new_size)
 803 {
 804         struct hlist_head *old_info_hash, *old_laddrhash;
 805         unsigned int old_size = fib_info_hash_size;
 806         unsigned int i, bytes;
 807
 808         spin_lock_bh(&fib_info_lock);
 809         old_info_hash = fib_info_hash;
 810         old_laddrhash = fib_info_laddrhash;
 811         fib_info_hash_size = new_size;
 812
 813         for (i = 0; i < old_size; i++) {
 814                 struct hlist_head *head = &fib_info_hash[i];
 815                 struct hlist_node *n;
 816                 struct fib_info *fi;
 817
 818                 hlist_for_each_entry_safe(fi, n, head, fib_hash) {
 819                         struct hlist_head *dest;
 820                         unsigned int new_hash;
 821
 822                         new_hash = fib_info_hashfn(fi);
 823                         dest = &new_info_hash[new_hash];
 824                         hlist_add_head(&fi->fib_hash, dest);
 825                 }
 826         }
 827         fib_info_hash = new_info_hash;
 828
 829         for (i = 0; i < old_size; i++) {
 830                 struct hlist_head *lhead = &fib_info_laddrhash[i];
 831                 struct hlist_node *n;
 832                 struct fib_info *fi;
 833
 834                 hlist_for_each_entry_safe(fi, n, lhead, fib_lhash) {
 835                         struct hlist_head *ldest;
 836                         unsigned int new_hash;
 837
 838                         new_hash = fib_laddr_hashfn(fi->fib_prefsrc);
 839                         ldest = &new_laddrhash[new_hash];
 840                         hlist_add_head(&fi->fib_lhash, ldest);
 841                 }
 842         }
 843         fib_info_laddrhash = new_laddrhash;
 844
 845         spin_unlock_bh(&fib_info_lock);
 846
 847         bytes = old_size * sizeof(struct hlist_head *);
 848         fib_info_hash_free(old_info_hash, bytes);
 849         fib_info_hash_free(old_laddrhash, bytes);
 850 }
 851
 852 __be32 fib_info_update_nh_saddr(struct net *net, struct fib_nh *nh)
 853 {
 854         nh->nh_saddr = inet_select_addr(nh->nh_dev,
 855                                         nh->nh_gw,
 856                                         nh->nh_parent->fib_scope);
 857         nh->nh_saddr_genid = atomic_read(&net->ipv4.dev_addr_genid);
 858
 859         return nh->nh_saddr;
 860 }
 861
 862 static bool fib_valid_prefsrc(struct fib_config *cfg, __be32 fib_prefsrc)
 863 {
 864         if (cfg->fc_type != RTN_LOCAL || !cfg->fc_dst ||
 865             fib_prefsrc != cfg->fc_dst) {
 866                 u32 tb_id = cfg->fc_table;
 867
 868                 if (tb_id == RT_TABLE_MAIN)
 869                         tb_id = RT_TABLE_LOCAL;
 870
 871                 if (inet_addr_type_table(cfg->fc_nlinfo.nl_net,
 872                                          fib_prefsrc, tb_id) != RTN_LOCAL) {
 873                         return false;
 874                 }
 875         }
 876         return true;
 877 }
 878
 879 static int
 880 fib_convert_metrics(struct fib_info *fi, const struct fib_config *cfg)
 881 {
 882         bool ecn_ca = false;
 883         struct nlattr *nla;
 884         int remaining;
 885
 886         if (!cfg->fc_mx)
 887                 return 0;
 888
 889         nla_for_each_attr(nla, cfg->fc_mx, cfg->fc_mx_len, remaining) {
 890                 int type = nla_type(nla);
 891                 u32 val;
 892
 893                 if (!type)
 894                         continue;
 895                 if (type > RTAX_MAX)
 896                         return -EINVAL;
 897
 898                 if (type == RTAX_CC_ALGO) {
 899                         char tmp[TCP_CA_NAME_MAX];
 900
 901                         nla_strlcpy(tmp, nla, sizeof(tmp));
 902                         val = tcp_ca_get_key_by_name(tmp, &ecn_ca);
 903                         if (val == TCP_CA_UNSPEC)
 904                                 return -EINVAL;
 905                 } else {
 906                         val = nla_get_u32(nla);
 907                 }
 908                 if (type == RTAX_ADVMSS && val > 65535 - 40)
 909                         val = 65535 - 40;
 910                 if (type == RTAX_MTU && val > 65535 - 15)
 911                         val = 65535 - 15;
 912                 if (type == RTAX_FEATURES && (val & ~RTAX_FEATURE_MASK))
 913                         return -EINVAL;
 914                 fi->fib_metrics[type - 1] = val;
 915         }
 916
 917         if (ecn_ca)
 918                 fi->fib_metrics[RTAX_FEATURES - 1] |= DST_FEATURE_ECN_CA;
 919
 920         return 0;
 921 }
 922
 923 struct fib_info *fib_create_info(struct fib_config *cfg)
 924 {
 925         int err;
 926         struct fib_info *fi = NULL;
 927         struct fib_info *ofi;
 928         int nhs = 1;
 929         struct net *net = cfg->fc_nlinfo.nl_net;
 930
 931         if (cfg->fc_type > RTN_MAX)
 932                 goto err_inval;
 933
 934         /* Fast check to catch the most weird cases */
 935         if (fib_props[cfg->fc_type].scope > cfg->fc_scope)
 936                 goto err_inval;
 937
 938 #ifdef CONFIG_IP_ROUTE_MULTIPATH
 939         if (cfg->fc_mp) {
 940                 nhs = fib_count_nexthops(cfg->fc_mp, cfg->fc_mp_len);
 941                 if (nhs == 0)
 942                         goto err_inval;
 943         }
 944 #endif
 945
 946         err = -ENOBUFS;
 947         if (fib_info_cnt >= fib_info_hash_size) {
 948                 unsigned int new_size = fib_info_hash_size << 1;
 949                 struct hlist_head *new_info_hash;
 950                 struct hlist_head *new_laddrhash;
 951                 unsigned int bytes;
 952
 953                 if (!new_size)
 954                         new_size = 16;
 955                 bytes = new_size * sizeof(struct hlist_head *);
 956                 new_info_hash = fib_info_hash_alloc(bytes);
 957                 new_laddrhash = fib_info_hash_alloc(bytes);
 958                 if (!new_info_hash || !new_laddrhash) {
 959                         fib_info_hash_free(new_info_hash, bytes);
 960                         fib_info_hash_free(new_laddrhash, bytes);
 961                 } else
 962                         fib_info_hash_move(new_info_hash, new_laddrhash, new_size);
 963
 964                 if (!fib_info_hash_size)
 965                         goto failure;
 966         }
 967
 968         fi = kzalloc(sizeof(*fi)+nhs*sizeof(struct fib_nh), GFP_KERNEL);
 969         if (!fi)
 970                 goto failure;
 971         fib_info_cnt++;
 972         if (cfg->fc_mx) {
 973                 fi->fib_metrics = kzalloc(sizeof(u32) * RTAX_MAX, GFP_KERNEL);
 974                 if (!fi->fib_metrics)
 975                         goto failure;
 976         } else
 977                 fi->fib_metrics = (u32 *) dst_default_metrics;
 978
 979         fi->fib_net = net;
 980         fi->fib_protocol = cfg->fc_protocol;
 981         fi->fib_scope = cfg->fc_scope;
 982         fi->fib_flags = cfg->fc_flags;
 983         fi->fib_priority = cfg->fc_priority;
 984         fi->fib_prefsrc = cfg->fc_prefsrc;
 985         fi->fib_type = cfg->fc_type;
 986
 987         fi->fib_nhs = nhs;
 988         change_nexthops(fi) {
 989                 nexthop_nh->nh_parent = fi;
 990                 nexthop_nh->nh_pcpu_rth_output = alloc_percpu(struct rtable __rcu *);
 991                 if (!nexthop_nh->nh_pcpu_rth_output)
 992                         goto failure;
 993         } endfor_nexthops(fi)
 994
 995         err = fib_convert_metrics(fi, cfg);
 996         if (err)
 997                 goto failure;
 998
 999         if (cfg->fc_mp) {
1000 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1001                 err = fib_get_nhs(fi, cfg->fc_mp, cfg->fc_mp_len, cfg);
1002                 if (err != 0)
1003                         goto failure;
1004                 if (cfg->fc_oif && fi->fib_nh->nh_oif != cfg->fc_oif)
1005                         goto err_inval;
1006                 if (cfg->fc_gw && fi->fib_nh->nh_gw != cfg->fc_gw)
1007                         goto err_inval;
1008 #ifdef CONFIG_IP_ROUTE_CLASSID
1009                 if (cfg->fc_flow && fi->fib_nh->nh_tclassid != cfg->fc_flow)
1010                         goto err_inval;
1011 #endif
1012 #else
1013                 goto err_inval;
1014 #endif
1015         } else {
1016                 struct fib_nh *nh = fi->fib_nh;
1017
1018                 if (cfg->fc_encap) {
1019                         struct lwtunnel_state *lwtstate;
1020                         struct net_device *dev = NULL;
1021
1022                         if (cfg->fc_encap_type == LWTUNNEL_ENCAP_NONE)
1023                                 goto err_inval;
1024                         if (cfg->fc_oif)
1025                                 dev = __dev_get_by_index(net, cfg->fc_oif);
1026                         err = lwtunnel_build_state(dev, cfg->fc_encap_type,
1027                                                    cfg->fc_encap, AF_INET, cfg,
1028                                                    &lwtstate);
1029                         if (err)
1030                                 goto failure;
1031
1032                         nh->nh_lwtstate = lwtstate_get(lwtstate);
1033                 }
1034                 nh->nh_oif = cfg->fc_oif;
1035                 nh->nh_gw = cfg->fc_gw;
1036                 nh->nh_flags = cfg->fc_flags;
1037 #ifdef CONFIG_IP_ROUTE_CLASSID
1038                 nh->nh_tclassid = cfg->fc_flow;
1039                 if (nh->nh_tclassid)
1040                         fi->fib_net->ipv4.fib_num_tclassid_users++;
1041 #endif
1042 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1043                 nh->nh_weight = 1;
1044 #endif
1045         }
1046
1047         if (fib_props[cfg->fc_type].error) {
1048                 if (cfg->fc_gw || cfg->fc_oif || cfg->fc_mp)
1049                         goto err_inval;
1050                 goto link_it;
1051         } else {
1052                 switch (cfg->fc_type) {
1053                 case RTN_UNICAST:
1054                 case RTN_LOCAL:
1055                 case RTN_BROADCAST:
1056                 case RTN_ANYCAST:
1057                 case RTN_MULTICAST:
1058                         break;
1059                 default:
1060                         goto err_inval;
1061                 }
1062         }
1063
1064         if (cfg->fc_scope > RT_SCOPE_HOST)
1065                 goto err_inval;
1066
1067         if (cfg->fc_scope == RT_SCOPE_HOST) {
1068                 struct fib_nh *nh = fi->fib_nh;
1069
1070                 /* Local address is added. */
1071                 if (nhs != 1 || nh->nh_gw)
1072                         goto err_inval;
1073                 nh->nh_scope = RT_SCOPE_NOWHERE;
1074                 nh->nh_dev = dev_get_by_index(net, fi->fib_nh->nh_oif);
1075                 err = -ENODEV;
1076                 if (!nh->nh_dev)
1077                         goto failure;
1078         } else {
1079                 int linkdown = 0;
1080
1081                 change_nexthops(fi) {
1082                         err = fib_check_nh(cfg, fi, nexthop_nh);
1083                         if (err != 0)
1084                                 goto failure;
1085                         if (nexthop_nh->nh_flags & RTNH_F_LINKDOWN)
1086                                 linkdown++;
1087                 } endfor_nexthops(fi)
1088                 if (linkdown == fi->fib_nhs)
1089                         fi->fib_flags |= RTNH_F_LINKDOWN;
1090         }
1091
1092         if (fi->fib_prefsrc && !fib_valid_prefsrc(cfg, fi->fib_prefsrc))
1093                 goto err_inval;
1094
1095         change_nexthops(fi) {
1096                 fib_info_update_nh_saddr(net, nexthop_nh);
1097         } endfor_nexthops(fi)
1098
1099 link_it:
1100         ofi = fib_find_info(fi);
1101         if (ofi) {
1102                 fi->fib_dead = 1;
1103                 free_fib_info(fi);
1104                 ofi->fib_treeref++;
1105                 return ofi;
1106         }
1107
1108         fi->fib_treeref++;
1109         atomic_inc(&fi->fib_clntref);
1110         spin_lock_bh(&fib_info_lock);
1111         hlist_add_head(&fi->fib_hash,
1112                        &fib_info_hash[fib_info_hashfn(fi)]);
1113         if (fi->fib_prefsrc) {
1114                 struct hlist_head *head;
1115
1116                 head = &fib_info_laddrhash[fib_laddr_hashfn(fi->fib_prefsrc)];
1117                 hlist_add_head(&fi->fib_lhash, head);
1118         }
1119         change_nexthops(fi) {
1120                 struct hlist_head *head;
1121                 unsigned int hash;
1122
1123                 if (!nexthop_nh->nh_dev)
1124                         continue;
1125                 hash = fib_devindex_hashfn(nexthop_nh->nh_dev->ifindex);
1126                 head = &fib_info_devhash[hash];
1127                 hlist_add_head(&nexthop_nh->nh_hash, head);
1128         } endfor_nexthops(fi)
1129         spin_unlock_bh(&fib_info_lock);
1130         return fi;
1131
1132 err_inval:
1133         err = -EINVAL;
1134
1135 failure:
1136         if (fi) {
1137                 fi->fib_dead = 1;
1138                 free_fib_info(fi);
1139         }
1140
1141         return ERR_PTR(err);
1142 }
1143
1144 int fib_dump_info(struct sk_buff *skb, u32 portid, u32 seq, int event,
1145                   u32 tb_id, u8 type, __be32 dst, int dst_len, u8 tos,
1146                   struct fib_info *fi, unsigned int flags)
1147 {
1148         struct nlmsghdr *nlh;
1149         struct rtmsg *rtm;
1150
1151         nlh = nlmsg_put(skb, portid, seq, event, sizeof(*rtm), flags);
1152         if (!nlh)
1153                 return -EMSGSIZE;
1154
1155         rtm = nlmsg_data(nlh);
1156         rtm->rtm_family = AF_INET;
1157         rtm->rtm_dst_len = dst_len;
1158         rtm->rtm_src_len = 0;
1159         rtm->rtm_tos = tos;
1160         if (tb_id < 256)
1161                 rtm->rtm_table = tb_id;
1162         else
1163                 rtm->rtm_table = RT_TABLE_COMPAT;
1164         if (nla_put_u32(skb, RTA_TABLE, tb_id))
1165                 goto nla_put_failure;
1166         rtm->rtm_type = type;
1167         rtm->rtm_flags = fi->fib_flags;
1168         rtm->rtm_scope = fi->fib_scope;
1169         rtm->rtm_protocol = fi->fib_protocol;
1170
1171         if (rtm->rtm_dst_len &&
1172             nla_put_in_addr(skb, RTA_DST, dst))
1173                 goto nla_put_failure;
1174         if (fi->fib_priority &&
1175             nla_put_u32(skb, RTA_PRIORITY, fi->fib_priority))
1176                 goto nla_put_failure;
1177         if (rtnetlink_put_metrics(skb, fi->fib_metrics) < 0)
1178                 goto nla_put_failure;
1179
1180         if (fi->fib_prefsrc &&
1181             nla_put_in_addr(skb, RTA_PREFSRC, fi->fib_prefsrc))
1182                 goto nla_put_failure;
1183         if (fi->fib_nhs == 1) {
1184                 struct in_device *in_dev;
1185
1186                 if (fi->fib_nh->nh_gw &&
1187                     nla_put_in_addr(skb, RTA_GATEWAY, fi->fib_nh->nh_gw))
1188                         goto nla_put_failure;
1189                 if (fi->fib_nh->nh_oif &&
1190                     nla_put_u32(skb, RTA_OIF, fi->fib_nh->nh_oif))
1191                         goto nla_put_failure;
1192                 if (fi->fib_nh->nh_flags & RTNH_F_LINKDOWN) {
1193                         in_dev = __in_dev_get_rtnl(fi->fib_nh->nh_dev);
1194                         if (in_dev &&
1195                             IN_DEV_IGNORE_ROUTES_WITH_LINKDOWN(in_dev))
1196                                 rtm->rtm_flags |= RTNH_F_DEAD;
1197                 }
1198 #ifdef CONFIG_IP_ROUTE_CLASSID
1199                 if (fi->fib_nh[0].nh_tclassid &&
1200                     nla_put_u32(skb, RTA_FLOW, fi->fib_nh[0].nh_tclassid))
1201                         goto nla_put_failure;
1202 #endif
1203                 if (fi->fib_nh->nh_lwtstate)
1204                         lwtunnel_fill_encap(skb, fi->fib_nh->nh_lwtstate);
1205         }
1206 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1207         if (fi->fib_nhs > 1) {
1208                 struct rtnexthop *rtnh;
1209                 struct nlattr *mp;
1210
1211                 mp = nla_nest_start(skb, RTA_MULTIPATH);
1212                 if (!mp)
1213                         goto nla_put_failure;
1214
1215                 for_nexthops(fi) {
1216                         struct in_device *in_dev;
1217
1218                         rtnh = nla_reserve_nohdr(skb, sizeof(*rtnh));
1219                         if (!rtnh)
1220                                 goto nla_put_failure;
1221
1222                         rtnh->rtnh_flags = nh->nh_flags & 0xFF;
1223                         if (nh->nh_flags & RTNH_F_LINKDOWN) {
1224                                 in_dev = __in_dev_get_rtnl(nh->nh_dev);
1225                                 if (in_dev &&
1226                                     IN_DEV_IGNORE_ROUTES_WITH_LINKDOWN(in_dev))
1227                                         rtnh->rtnh_flags |= RTNH_F_DEAD;
1228                         }
1229                         rtnh->rtnh_hops = nh->nh_weight - 1;
1230                         rtnh->rtnh_ifindex = nh->nh_oif;
1231
1232                         if (nh->nh_gw &&
1233                             nla_put_in_addr(skb, RTA_GATEWAY, nh->nh_gw))
1234                                 goto nla_put_failure;
1235 #ifdef CONFIG_IP_ROUTE_CLASSID
1236                         if (nh->nh_tclassid &&
1237                             nla_put_u32(skb, RTA_FLOW, nh->nh_tclassid))
1238                                 goto nla_put_failure;
1239 #endif
1240                         if (nh->nh_lwtstate)
1241                                 lwtunnel_fill_encap(skb, nh->nh_lwtstate);
1242                         /* length of rtnetlink header + attributes */
1243                         rtnh->rtnh_len = nlmsg_get_pos(skb) - (void *) rtnh;
1244                 } endfor_nexthops(fi);
1245
1246                 nla_nest_end(skb, mp);
1247         }
1248 #endif
1249         nlmsg_end(skb, nlh);
1250         return 0;
1251
1252 nla_put_failure:
1253         nlmsg_cancel(skb, nlh);
1254         return -EMSGSIZE;
1255 }
1256
1257 /*
1258  * Update FIB if:
1259  * - local address disappeared -> we must delete all the entries
1260  *   referring to it.
1261  * - device went down -> we must shutdown all nexthops going via it.
1262  */
1263 int fib_sync_down_addr(struct net *net, __be32 local)
1264 {
1265         int ret = 0;
1266         unsigned int hash = fib_laddr_hashfn(local);
1267         struct hlist_head *head = &fib_info_laddrhash[hash];
1268         struct fib_info *fi;
1269
1270         if (!fib_info_laddrhash || local == 0)
1271                 return 0;
1272
1273         hlist_for_each_entry(fi, head, fib_lhash) {
1274                 if (!net_eq(fi->fib_net, net))
1275                         continue;
1276                 if (fi->fib_prefsrc == local) {
1277                         fi->fib_flags |= RTNH_F_DEAD;
1278                         ret++;
1279                 }
1280         }
1281         return ret;
1282 }
1283
1284 int fib_sync_down_dev(struct net_device *dev, unsigned long event)
1285 {
1286         int ret = 0;
1287         int scope = RT_SCOPE_NOWHERE;
1288         struct fib_info *prev_fi = NULL;
1289         unsigned int hash = fib_devindex_hashfn(dev->ifindex);
1290         struct hlist_head *head = &fib_info_devhash[hash];
1291         struct fib_nh *nh;
1292
1293         if (event == NETDEV_UNREGISTER ||
1294             event == NETDEV_DOWN)
1295                 scope = -1;
1296
1297         hlist_for_each_entry(nh, head, nh_hash) {
1298                 struct fib_info *fi = nh->nh_parent;
1299                 int dead;
1300
1301                 BUG_ON(!fi->fib_nhs);
1302                 if (nh->nh_dev != dev || fi == prev_fi)
1303                         continue;
1304                 prev_fi = fi;
1305                 dead = 0;
1306                 change_nexthops(fi) {
1307                         if (nexthop_nh->nh_flags & RTNH_F_DEAD)
1308                                 dead++;
1309                         else if (nexthop_nh->nh_dev == dev &&
1310                                  nexthop_nh->nh_scope != scope) {
1311                                 switch (event) {
1312                                 case NETDEV_DOWN:
1313                                 case NETDEV_UNREGISTER:
1314                                         nexthop_nh->nh_flags |= RTNH_F_DEAD;
1315                                         /* fall through */
1316                                 case NETDEV_CHANGE:
1317                                         nexthop_nh->nh_flags |= RTNH_F_LINKDOWN;
1318                                         break;
1319                                 }
1320 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1321                                 spin_lock_bh(&fib_multipath_lock);
1322                                 fi->fib_power -= nexthop_nh->nh_power;
1323                                 nexthop_nh->nh_power = 0;
1324                                 spin_unlock_bh(&fib_multipath_lock);
1325 #endif
1326                                 dead++;
1327                         }
1328 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1329                         if (event == NETDEV_UNREGISTER &&
1330                             nexthop_nh->nh_dev == dev) {
1331                                 dead = fi->fib_nhs;
1332                                 break;
1333                         }
1334 #endif
1335                 } endfor_nexthops(fi)
1336                 if (dead == fi->fib_nhs) {
1337                         switch (event) {
1338                         case NETDEV_DOWN:
1339                         case NETDEV_UNREGISTER:
1340                                 fi->fib_flags |= RTNH_F_DEAD;
1341                                 /* fall through */
1342                         case NETDEV_CHANGE:
1343                                 fi->fib_flags |= RTNH_F_LINKDOWN;
1344                                 break;
1345                         }
1346                         ret++;
1347                 }
1348         }
1349
1350         return ret;
1351 }
1352
1353 /* Must be invoked inside of an RCU protected region.  */
1354 void fib_select_default(const struct flowi4 *flp, struct fib_result *res)
1355 {
1356         struct fib_info *fi = NULL, *last_resort = NULL;
1357         struct hlist_head *fa_head = res->fa_head;
1358         struct fib_table *tb = res->table;
1359         u8 slen = 32 - res->prefixlen;
1360         int order = -1, last_idx = -1;
1361         struct fib_alias *fa, *fa1 = NULL;
1362         u32 last_prio = res->fi->fib_priority;
1363         u8 last_tos = 0;
1364
1365         hlist_for_each_entry_rcu(fa, fa_head, fa_list) {
1366                 struct fib_info *next_fi = fa->fa_info;
1367
1368                 if (fa->fa_slen != slen)
1369                         continue;
1370                 if (fa->fa_tos && fa->fa_tos != flp->flowi4_tos)
1371                         continue;
1372                 if (fa->tb_id != tb->tb_id)
1373                         continue;
1374                 if (next_fi->fib_priority > last_prio &&
1375                     fa->fa_tos == last_tos) {
1376                         if (last_tos)
1377                                 continue;
1378                         break;
1379                 }
1380                 if (next_fi->fib_flags & RTNH_F_DEAD)
1381                         continue;
1382                 last_tos = fa->fa_tos;
1383                 last_prio = next_fi->fib_priority;
1384
1385                 if (next_fi->fib_scope != res->scope ||
1386                     fa->fa_type != RTN_UNICAST)
1387                         continue;
1388                 if (!next_fi->fib_nh[0].nh_gw ||
1389                     next_fi->fib_nh[0].nh_scope != RT_SCOPE_LINK)
1390                         continue;
1391
1392                 fib_alias_accessed(fa);
1393
1394                 if (!fi) {
1395                         if (next_fi != res->fi)
1396                                 break;
1397                         fa1 = fa;
1398                 } else if (!fib_detect_death(fi, order, &last_resort,
1399                                              &last_idx, fa1->fa_default)) {
1400                         fib_result_assign(res, fi);
1401                         fa1->fa_default = order;
1402                         goto out;
1403                 }
1404                 fi = next_fi;
1405                 order++;
1406         }
1407
1408         if (order <= 0 || !fi) {
1409                 if (fa1)
1410                         fa1->fa_default = -1;
1411                 goto out;
1412         }
1413
1414         if (!fib_detect_death(fi, order, &last_resort, &last_idx,
1415                               fa1->fa_default)) {
1416                 fib_result_assign(res, fi);
1417                 fa1->fa_default = order;
1418                 goto out;
1419         }
1420
1421         if (last_idx >= 0)
1422                 fib_result_assign(res, last_resort);
1423         fa1->fa_default = last_idx;
1424 out:
1425         return;
1426 }
1427
1428 /*
1429  * Dead device goes up. We wake up dead nexthops.
1430  * It takes sense only on multipath routes.
1431  */
1432 int fib_sync_up(struct net_device *dev, unsigned int nh_flags)
1433 {
1434         struct fib_info *prev_fi;
1435         unsigned int hash;
1436         struct hlist_head *head;
1437         struct fib_nh *nh;
1438         int ret;
1439
1440         if (!(dev->flags & IFF_UP))
1441                 return 0;
1442
1443         prev_fi = NULL;
1444         hash = fib_devindex_hashfn(dev->ifindex);
1445         head = &fib_info_devhash[hash];
1446         ret = 0;
1447
1448         hlist_for_each_entry(nh, head, nh_hash) {
1449                 struct fib_info *fi = nh->nh_parent;
1450                 int alive;
1451
1452                 BUG_ON(!fi->fib_nhs);
1453                 if (nh->nh_dev != dev || fi == prev_fi)
1454                         continue;
1455
1456                 prev_fi = fi;
1457                 alive = 0;
1458                 change_nexthops(fi) {
1459                         if (!(nexthop_nh->nh_flags & nh_flags)) {
1460                                 alive++;
1461                                 continue;
1462                         }
1463                         if (!nexthop_nh->nh_dev ||
1464                             !(nexthop_nh->nh_dev->flags & IFF_UP))
1465                                 continue;
1466                         if (nexthop_nh->nh_dev != dev ||
1467                             !__in_dev_get_rtnl(dev))
1468                                 continue;
1469                         alive++;
1470 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1471                         spin_lock_bh(&fib_multipath_lock);
1472                         nexthop_nh->nh_power = 0;
1473                         nexthop_nh->nh_flags &= ~nh_flags;
1474                         spin_unlock_bh(&fib_multipath_lock);
1475 #else
1476                         nexthop_nh->nh_flags &= ~nh_flags;
1477 #endif
1478                 } endfor_nexthops(fi)
1479
1480                 if (alive > 0) {
1481                         fi->fib_flags &= ~nh_flags;
1482                         ret++;
1483                 }
1484         }
1485
1486         return ret;
1487 }
1488
1489 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1490
1491 /*
1492  * The algorithm is suboptimal, but it provides really
1493  * fair weighted route distribution.
1494  */
1495 void fib_select_multipath(struct fib_result *res)
1496 {
1497         struct fib_info *fi = res->fi;
1498         struct in_device *in_dev;
1499         int w;
1500
1501         spin_lock_bh(&fib_multipath_lock);
1502         if (fi->fib_power <= 0) {
1503                 int power = 0;
1504                 change_nexthops(fi) {
1505                         in_dev = __in_dev_get_rcu(nexthop_nh->nh_dev);
1506                         if (nexthop_nh->nh_flags & RTNH_F_DEAD)
1507                                 continue;
1508                         if (in_dev &&
1509                             IN_DEV_IGNORE_ROUTES_WITH_LINKDOWN(in_dev) &&
1510                             nexthop_nh->nh_flags & RTNH_F_LINKDOWN)
1511                                 continue;
1512                         power += nexthop_nh->nh_weight;
1513                         nexthop_nh->nh_power = nexthop_nh->nh_weight;
1514                 } endfor_nexthops(fi);
1515                 fi->fib_power = power;
1516                 if (power <= 0) {
1517                         spin_unlock_bh(&fib_multipath_lock);
1518                         /* Race condition: route has just become dead. */
1519                         res->nh_sel = 0;
1520                         return;
1521                 }
1522         }
1523
1524
1525         /* w should be random number [0..fi->fib_power-1],
1526          * it is pretty bad approximation.
1527          */
1528
1529         w = jiffies % fi->fib_power;
1530
1531         change_nexthops(fi) {
1532                 if (!(nexthop_nh->nh_flags & RTNH_F_DEAD) &&
1533                     nexthop_nh->nh_power) {
1534                         w -= nexthop_nh->nh_power;
1535                         if (w <= 0) {
1536                                 nexthop_nh->nh_power--;
1537                                 fi->fib_power--;
1538                                 res->nh_sel = nhsel;
1539                                 spin_unlock_bh(&fib_multipath_lock);
1540                                 return;
1541                         }
1542                 }
1543         } endfor_nexthops(fi);
1544
1545         /* Race condition: route has just become dead. */
1546         res->nh_sel = 0;
1547         spin_unlock_bh(&fib_multipath_lock);
1548 }
1549 #endif