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, &lwtstate);
 515                                 if (ret)
 516                                         goto errout;
 517                                 nexthop_nh->nh_lwtstate =
 518                                         lwtstate_get(lwtstate);
 519                         }
 520                 }
 521
 522                 rtnh = rtnh_next(rtnh, &remaining);
 523         } endfor_nexthops(fi);
 524
 525         return 0;
 526
 527 err_inval:
 528         ret = -EINVAL;
 529
 530 errout:
 531         return ret;
 532 }
 533
 534 #endif
 535
 536 int fib_encap_match(struct net *net, u16 encap_type,
 537                     struct nlattr *encap,
 538                     int oif, const struct fib_nh *nh)
 539 {
 540         struct lwtunnel_state *lwtstate;
 541         struct net_device *dev = NULL;
 542         int ret;
 543
 544         if (encap_type == LWTUNNEL_ENCAP_NONE)
 545                 return 0;
 546
 547         if (oif)
 548                 dev = __dev_get_by_index(net, oif);
 549         ret = lwtunnel_build_state(dev, encap_type,
 550                                    encap, &lwtstate);
 551         if (!ret)
 552                 return lwtunnel_cmp_encap(lwtstate, nh->nh_lwtstate);
 553
 554         return 0;
 555 }
 556
 557 int fib_nh_match(struct fib_config *cfg, struct fib_info *fi)
 558 {
 559         struct net *net = cfg->fc_nlinfo.nl_net;
 560 #ifdef CONFIG_IP_ROUTE_MULTIPATH
 561         struct rtnexthop *rtnh;
 562         int remaining;
 563 #endif
 564
 565         if (cfg->fc_priority && cfg->fc_priority != fi->fib_priority)
 566                 return 1;
 567
 568         if (cfg->fc_oif || cfg->fc_gw) {
 569                 if (cfg->fc_encap) {
 570                         if (fib_encap_match(net, cfg->fc_encap_type,
 571                                             cfg->fc_encap, cfg->fc_oif,
 572                                             fi->fib_nh))
 573                             return 1;
 574                 }
 575                 if ((!cfg->fc_oif || cfg->fc_oif == fi->fib_nh->nh_oif) &&
 576                     (!cfg->fc_gw  || cfg->fc_gw == fi->fib_nh->nh_gw))
 577                         return 0;
 578                 return 1;
 579         }
 580
 581 #ifdef CONFIG_IP_ROUTE_MULTIPATH
 582         if (!cfg->fc_mp)
 583                 return 0;
 584
 585         rtnh = cfg->fc_mp;
 586         remaining = cfg->fc_mp_len;
 587
 588         for_nexthops(fi) {
 589                 int attrlen;
 590
 591                 if (!rtnh_ok(rtnh, remaining))
 592                         return -EINVAL;
 593
 594                 if (rtnh->rtnh_ifindex && rtnh->rtnh_ifindex != nh->nh_oif)
 595                         return 1;
 596
 597                 attrlen = rtnh_attrlen(rtnh);
 598                 if (attrlen > 0) {
 599                         struct nlattr *nla, *attrs = rtnh_attrs(rtnh);
 600
 601                         nla = nla_find(attrs, attrlen, RTA_GATEWAY);
 602                         if (nla && nla_get_in_addr(nla) != nh->nh_gw)
 603                                 return 1;
 604 #ifdef CONFIG_IP_ROUTE_CLASSID
 605                         nla = nla_find(attrs, attrlen, RTA_FLOW);
 606                         if (nla && nla_get_u32(nla) != nh->nh_tclassid)
 607                                 return 1;
 608 #endif
 609                 }
 610
 611                 rtnh = rtnh_next(rtnh, &remaining);
 612         } endfor_nexthops(fi);
 613 #endif
 614         return 0;
 615 }
 616
 617
 618 /*
 619  * Picture
 620  * -------
 621  *
 622  * Semantics of nexthop is very messy by historical reasons.
 623  * We have to take into account, that:
 624  * a) gateway can be actually local interface address,
 625  *    so that gatewayed route is direct.
 626  * b) gateway must be on-link address, possibly
 627  *    described not by an ifaddr, but also by a direct route.
 628  * c) If both gateway and interface are specified, they should not
 629  *    contradict.
 630  * d) If we use tunnel routes, gateway could be not on-link.
 631  *
 632  * Attempt to reconcile all of these (alas, self-contradictory) conditions
 633  * results in pretty ugly and hairy code with obscure logic.
 634  *
 635  * I chose to generalized it instead, so that the size
 636  * of code does not increase practically, but it becomes
 637  * much more general.
 638  * Every prefix is assigned a "scope" value: "host" is local address,
 639  * "link" is direct route,
 640  * [ ... "site" ... "interior" ... ]
 641  * and "universe" is true gateway route with global meaning.
 642  *
 643  * Every prefix refers to a set of "nexthop"s (gw, oif),
 644  * where gw must have narrower scope. This recursion stops
 645  * when gw has LOCAL scope or if "nexthop" is declared ONLINK,
 646  * which means that gw is forced to be on link.
 647  *
 648  * Code is still hairy, but now it is apparently logically
 649  * consistent and very flexible. F.e. as by-product it allows
 650  * to co-exists in peace independent exterior and interior
 651  * routing processes.
 652  *
 653  * Normally it looks as following.
 654  *
 655  * {universe prefix}  -> (gw, oif) [scope link]
 656  *                |
 657  *                |-> {link prefix} -> (gw, oif) [scope local]
 658  *                                      |
 659  *                                      |-> {local prefix} (terminal node)
 660  */
 661 static int fib_check_nh(struct fib_config *cfg, struct fib_info *fi,
 662                         struct fib_nh *nh)
 663 {
 664         int err;
 665         struct net *net;
 666         struct net_device *dev;
 667
 668         net = cfg->fc_nlinfo.nl_net;
 669         if (nh->nh_gw) {
 670                 struct fib_result res;
 671
 672                 if (nh->nh_flags & RTNH_F_ONLINK) {
 673
 674                         if (cfg->fc_scope >= RT_SCOPE_LINK)
 675                                 return -EINVAL;
 676                         if (inet_addr_type(net, nh->nh_gw) != RTN_UNICAST)
 677                                 return -EINVAL;
 678                         dev = __dev_get_by_index(net, nh->nh_oif);
 679                         if (!dev)
 680                                 return -ENODEV;
 681                         if (!(dev->flags & IFF_UP))
 682                                 return -ENETDOWN;
 683                         if (!netif_carrier_ok(dev))
 684                                 nh->nh_flags |= RTNH_F_LINKDOWN;
 685                         nh->nh_dev = dev;
 686                         dev_hold(dev);
 687                         nh->nh_scope = RT_SCOPE_LINK;
 688                         return 0;
 689                 }
 690                 rcu_read_lock();
 691                 {
 692                         struct flowi4 fl4 = {
 693                                 .daddr = nh->nh_gw,
 694                                 .flowi4_scope = cfg->fc_scope + 1,
 695                                 .flowi4_oif = nh->nh_oif,
 696                                 .flowi4_iif = LOOPBACK_IFINDEX,
 697                         };
 698
 699                         /* It is not necessary, but requires a bit of thinking */
 700                         if (fl4.flowi4_scope < RT_SCOPE_LINK)
 701                                 fl4.flowi4_scope = RT_SCOPE_LINK;
 702                         err = fib_lookup(net, &fl4, &res,
 703                                          FIB_LOOKUP_IGNORE_LINKSTATE);
 704                         if (err) {
 705                                 rcu_read_unlock();
 706                                 return err;
 707                         }
 708                 }
 709                 err = -EINVAL;
 710                 if (res.type != RTN_UNICAST && res.type != RTN_LOCAL)
 711                         goto out;
 712                 nh->nh_scope = res.scope;
 713                 nh->nh_oif = FIB_RES_OIF(res);
 714                 nh->nh_dev = dev = FIB_RES_DEV(res);
 715                 if (!dev)
 716                         goto out;
 717                 dev_hold(dev);
 718                 if (!netif_carrier_ok(dev))
 719                         nh->nh_flags |= RTNH_F_LINKDOWN;
 720                 err = (dev->flags & IFF_UP) ? 0 : -ENETDOWN;
 721         } else {
 722                 struct in_device *in_dev;
 723
 724                 if (nh->nh_flags & (RTNH_F_PERVASIVE | RTNH_F_ONLINK))
 725                         return -EINVAL;
 726
 727                 rcu_read_lock();
 728                 err = -ENODEV;
 729                 in_dev = inetdev_by_index(net, nh->nh_oif);
 730                 if (!in_dev)
 731                         goto out;
 732                 err = -ENETDOWN;
 733                 if (!(in_dev->dev->flags & IFF_UP))
 734                         goto out;
 735                 nh->nh_dev = in_dev->dev;
 736                 dev_hold(nh->nh_dev);
 737                 nh->nh_scope = RT_SCOPE_HOST;
 738                 if (!netif_carrier_ok(nh->nh_dev))
 739                         nh->nh_flags |= RTNH_F_LINKDOWN;
 740                 err = 0;
 741         }
 742 out:
 743         rcu_read_unlock();
 744         return err;
 745 }
 746
 747 static inline unsigned int fib_laddr_hashfn(__be32 val)
 748 {
 749         unsigned int mask = (fib_info_hash_size - 1);
 750
 751         return ((__force u32)val ^
 752                 ((__force u32)val >> 7) ^
 753                 ((__force u32)val >> 14)) & mask;
 754 }
 755
 756 static struct hlist_head *fib_info_hash_alloc(int bytes)
 757 {
 758         if (bytes <= PAGE_SIZE)
 759                 return kzalloc(bytes, GFP_KERNEL);
 760         else
 761                 return (struct hlist_head *)
 762                         __get_free_pages(GFP_KERNEL | __GFP_ZERO,
 763                                          get_order(bytes));
 764 }
 765
 766 static void fib_info_hash_free(struct hlist_head *hash, int bytes)
 767 {
 768         if (!hash)
 769                 return;
 770
 771         if (bytes <= PAGE_SIZE)
 772                 kfree(hash);
 773         else
 774                 free_pages((unsigned long) hash, get_order(bytes));
 775 }
 776
 777 static void fib_info_hash_move(struct hlist_head *new_info_hash,
 778                                struct hlist_head *new_laddrhash,
 779                                unsigned int new_size)
 780 {
 781         struct hlist_head *old_info_hash, *old_laddrhash;
 782         unsigned int old_size = fib_info_hash_size;
 783         unsigned int i, bytes;
 784
 785         spin_lock_bh(&fib_info_lock);
 786         old_info_hash = fib_info_hash;
 787         old_laddrhash = fib_info_laddrhash;
 788         fib_info_hash_size = new_size;
 789
 790         for (i = 0; i < old_size; i++) {
 791                 struct hlist_head *head = &fib_info_hash[i];
 792                 struct hlist_node *n;
 793                 struct fib_info *fi;
 794
 795                 hlist_for_each_entry_safe(fi, n, head, fib_hash) {
 796                         struct hlist_head *dest;
 797                         unsigned int new_hash;
 798
 799                         new_hash = fib_info_hashfn(fi);
 800                         dest = &new_info_hash[new_hash];
 801                         hlist_add_head(&fi->fib_hash, dest);
 802                 }
 803         }
 804         fib_info_hash = new_info_hash;
 805
 806         for (i = 0; i < old_size; i++) {
 807                 struct hlist_head *lhead = &fib_info_laddrhash[i];
 808                 struct hlist_node *n;
 809                 struct fib_info *fi;
 810
 811                 hlist_for_each_entry_safe(fi, n, lhead, fib_lhash) {
 812                         struct hlist_head *ldest;
 813                         unsigned int new_hash;
 814
 815                         new_hash = fib_laddr_hashfn(fi->fib_prefsrc);
 816                         ldest = &new_laddrhash[new_hash];
 817                         hlist_add_head(&fi->fib_lhash, ldest);
 818                 }
 819         }
 820         fib_info_laddrhash = new_laddrhash;
 821
 822         spin_unlock_bh(&fib_info_lock);
 823
 824         bytes = old_size * sizeof(struct hlist_head *);
 825         fib_info_hash_free(old_info_hash, bytes);
 826         fib_info_hash_free(old_laddrhash, bytes);
 827 }
 828
 829 __be32 fib_info_update_nh_saddr(struct net *net, struct fib_nh *nh)
 830 {
 831         nh->nh_saddr = inet_select_addr(nh->nh_dev,
 832                                         nh->nh_gw,
 833                                         nh->nh_parent->fib_scope);
 834         nh->nh_saddr_genid = atomic_read(&net->ipv4.dev_addr_genid);
 835
 836         return nh->nh_saddr;
 837 }
 838
 839 struct fib_info *fib_create_info(struct fib_config *cfg)
 840 {
 841         int err;
 842         struct fib_info *fi = NULL;
 843         struct fib_info *ofi;
 844         int nhs = 1;
 845         struct net *net = cfg->fc_nlinfo.nl_net;
 846
 847         if (cfg->fc_type > RTN_MAX)
 848                 goto err_inval;
 849
 850         /* Fast check to catch the most weird cases */
 851         if (fib_props[cfg->fc_type].scope > cfg->fc_scope)
 852                 goto err_inval;
 853
 854 #ifdef CONFIG_IP_ROUTE_MULTIPATH
 855         if (cfg->fc_mp) {
 856                 nhs = fib_count_nexthops(cfg->fc_mp, cfg->fc_mp_len);
 857                 if (nhs == 0)
 858                         goto err_inval;
 859         }
 860 #endif
 861
 862         err = -ENOBUFS;
 863         if (fib_info_cnt >= fib_info_hash_size) {
 864                 unsigned int new_size = fib_info_hash_size << 1;
 865                 struct hlist_head *new_info_hash;
 866                 struct hlist_head *new_laddrhash;
 867                 unsigned int bytes;
 868
 869                 if (!new_size)
 870                         new_size = 16;
 871                 bytes = new_size * sizeof(struct hlist_head *);
 872                 new_info_hash = fib_info_hash_alloc(bytes);
 873                 new_laddrhash = fib_info_hash_alloc(bytes);
 874                 if (!new_info_hash || !new_laddrhash) {
 875                         fib_info_hash_free(new_info_hash, bytes);
 876                         fib_info_hash_free(new_laddrhash, bytes);
 877                 } else
 878                         fib_info_hash_move(new_info_hash, new_laddrhash, new_size);
 879
 880                 if (!fib_info_hash_size)
 881                         goto failure;
 882         }
 883
 884         fi = kzalloc(sizeof(*fi)+nhs*sizeof(struct fib_nh), GFP_KERNEL);
 885         if (!fi)
 886                 goto failure;
 887         fib_info_cnt++;
 888         if (cfg->fc_mx) {
 889                 fi->fib_metrics = kzalloc(sizeof(u32) * RTAX_MAX, GFP_KERNEL);
 890                 if (!fi->fib_metrics)
 891                         goto failure;
 892         } else
 893                 fi->fib_metrics = (u32 *) dst_default_metrics;
 894
 895         fi->fib_net = net;
 896         fi->fib_protocol = cfg->fc_protocol;
 897         fi->fib_scope = cfg->fc_scope;
 898         fi->fib_flags = cfg->fc_flags;
 899         fi->fib_priority = cfg->fc_priority;
 900         fi->fib_prefsrc = cfg->fc_prefsrc;
 901         fi->fib_type = cfg->fc_type;
 902
 903         fi->fib_nhs = nhs;
 904         change_nexthops(fi) {
 905                 nexthop_nh->nh_parent = fi;
 906                 nexthop_nh->nh_pcpu_rth_output = alloc_percpu(struct rtable __rcu *);
 907                 if (!nexthop_nh->nh_pcpu_rth_output)
 908                         goto failure;
 909         } endfor_nexthops(fi)
 910
 911         if (cfg->fc_mx) {
 912                 struct nlattr *nla;
 913                 int remaining;
 914
 915                 nla_for_each_attr(nla, cfg->fc_mx, cfg->fc_mx_len, remaining) {
 916                         int type = nla_type(nla);
 917
 918                         if (type) {
 919                                 u32 val;
 920
 921                                 if (type > RTAX_MAX)
 922                                         goto err_inval;
 923                                 if (type == RTAX_CC_ALGO) {
 924                                         char tmp[TCP_CA_NAME_MAX];
 925
 926                                         nla_strlcpy(tmp, nla, sizeof(tmp));
 927                                         val = tcp_ca_get_key_by_name(tmp);
 928                                         if (val == TCP_CA_UNSPEC)
 929                                                 goto err_inval;
 930                                 } else {
 931                                         val = nla_get_u32(nla);
 932                                 }
 933                                 if (type == RTAX_ADVMSS && val > 65535 - 40)
 934                                         val = 65535 - 40;
 935                                 if (type == RTAX_MTU && val > 65535 - 15)
 936                                         val = 65535 - 15;
 937                                 fi->fib_metrics[type - 1] = val;
 938                         }
 939                 }
 940         }
 941
 942         if (cfg->fc_mp) {
 943 #ifdef CONFIG_IP_ROUTE_MULTIPATH
 944                 err = fib_get_nhs(fi, cfg->fc_mp, cfg->fc_mp_len, cfg);
 945                 if (err != 0)
 946                         goto failure;
 947                 if (cfg->fc_oif && fi->fib_nh->nh_oif != cfg->fc_oif)
 948                         goto err_inval;
 949                 if (cfg->fc_gw && fi->fib_nh->nh_gw != cfg->fc_gw)
 950                         goto err_inval;
 951 #ifdef CONFIG_IP_ROUTE_CLASSID
 952                 if (cfg->fc_flow && fi->fib_nh->nh_tclassid != cfg->fc_flow)
 953                         goto err_inval;
 954 #endif
 955 #else
 956                 goto err_inval;
 957 #endif
 958         } else {
 959                 struct fib_nh *nh = fi->fib_nh;
 960
 961                 if (cfg->fc_encap) {
 962                         struct lwtunnel_state *lwtstate;
 963                         struct net_device *dev = NULL;
 964
 965                         if (cfg->fc_encap_type == LWTUNNEL_ENCAP_NONE)
 966                                 goto err_inval;
 967                         if (cfg->fc_oif)
 968                                 dev = __dev_get_by_index(net, cfg->fc_oif);
 969                         err = lwtunnel_build_state(dev, cfg->fc_encap_type,
 970                                                    cfg->fc_encap, &lwtstate);
 971                         if (err)
 972                                 goto failure;
 973
 974                         nh->nh_lwtstate = lwtstate_get(lwtstate);
 975                 }
 976                 nh->nh_oif = cfg->fc_oif;
 977                 nh->nh_gw = cfg->fc_gw;
 978                 nh->nh_flags = cfg->fc_flags;
 979 #ifdef CONFIG_IP_ROUTE_CLASSID
 980                 nh->nh_tclassid = cfg->fc_flow;
 981                 if (nh->nh_tclassid)
 982                         fi->fib_net->ipv4.fib_num_tclassid_users++;
 983 #endif
 984 #ifdef CONFIG_IP_ROUTE_MULTIPATH
 985                 nh->nh_weight = 1;
 986 #endif
 987         }
 988
 989         if (fib_props[cfg->fc_type].error) {
 990                 if (cfg->fc_gw || cfg->fc_oif || cfg->fc_mp)
 991                         goto err_inval;
 992                 goto link_it;
 993         } else {
 994                 switch (cfg->fc_type) {
 995                 case RTN_UNICAST:
 996                 case RTN_LOCAL:
 997                 case RTN_BROADCAST:
 998                 case RTN_ANYCAST:
 999                 case RTN_MULTICAST:
1000                         break;
1001                 default:
1002                         goto err_inval;
1003                 }
1004         }
1005
1006         if (cfg->fc_scope > RT_SCOPE_HOST)
1007                 goto err_inval;
1008
1009         if (cfg->fc_scope == RT_SCOPE_HOST) {
1010                 struct fib_nh *nh = fi->fib_nh;
1011
1012                 /* Local address is added. */
1013                 if (nhs != 1 || nh->nh_gw)
1014                         goto err_inval;
1015                 nh->nh_scope = RT_SCOPE_NOWHERE;
1016                 nh->nh_dev = dev_get_by_index(net, fi->fib_nh->nh_oif);
1017                 err = -ENODEV;
1018                 if (!nh->nh_dev)
1019                         goto failure;
1020         } else {
1021                 int linkdown = 0;
1022
1023                 change_nexthops(fi) {
1024                         err = fib_check_nh(cfg, fi, nexthop_nh);
1025                         if (err != 0)
1026                                 goto failure;
1027                         if (nexthop_nh->nh_flags & RTNH_F_LINKDOWN)
1028                                 linkdown++;
1029                 } endfor_nexthops(fi)
1030                 if (linkdown == fi->fib_nhs)
1031                         fi->fib_flags |= RTNH_F_LINKDOWN;
1032         }
1033
1034         if (fi->fib_prefsrc) {
1035                 if (cfg->fc_type != RTN_LOCAL || !cfg->fc_dst ||
1036                     fi->fib_prefsrc != cfg->fc_dst)
1037                         if (inet_addr_type(net, fi->fib_prefsrc) != RTN_LOCAL)
1038                                 goto err_inval;
1039         }
1040
1041         change_nexthops(fi) {
1042                 fib_info_update_nh_saddr(net, nexthop_nh);
1043         } endfor_nexthops(fi)
1044
1045 link_it:
1046         ofi = fib_find_info(fi);
1047         if (ofi) {
1048                 fi->fib_dead = 1;
1049                 free_fib_info(fi);
1050                 ofi->fib_treeref++;
1051                 return ofi;
1052         }
1053
1054         fi->fib_treeref++;
1055         atomic_inc(&fi->fib_clntref);
1056         spin_lock_bh(&fib_info_lock);
1057         hlist_add_head(&fi->fib_hash,
1058                        &fib_info_hash[fib_info_hashfn(fi)]);
1059         if (fi->fib_prefsrc) {
1060                 struct hlist_head *head;
1061
1062                 head = &fib_info_laddrhash[fib_laddr_hashfn(fi->fib_prefsrc)];
1063                 hlist_add_head(&fi->fib_lhash, head);
1064         }
1065         change_nexthops(fi) {
1066                 struct hlist_head *head;
1067                 unsigned int hash;
1068
1069                 if (!nexthop_nh->nh_dev)
1070                         continue;
1071                 hash = fib_devindex_hashfn(nexthop_nh->nh_dev->ifindex);
1072                 head = &fib_info_devhash[hash];
1073                 hlist_add_head(&nexthop_nh->nh_hash, head);
1074         } endfor_nexthops(fi)
1075         spin_unlock_bh(&fib_info_lock);
1076         return fi;
1077
1078 err_inval:
1079         err = -EINVAL;
1080
1081 failure:
1082         if (fi) {
1083                 fi->fib_dead = 1;
1084                 free_fib_info(fi);
1085         }
1086
1087         return ERR_PTR(err);
1088 }
1089
1090 int fib_dump_info(struct sk_buff *skb, u32 portid, u32 seq, int event,
1091                   u32 tb_id, u8 type, __be32 dst, int dst_len, u8 tos,
1092                   struct fib_info *fi, unsigned int flags)
1093 {
1094         struct nlmsghdr *nlh;
1095         struct rtmsg *rtm;
1096
1097         nlh = nlmsg_put(skb, portid, seq, event, sizeof(*rtm), flags);
1098         if (!nlh)
1099                 return -EMSGSIZE;
1100
1101         rtm = nlmsg_data(nlh);
1102         rtm->rtm_family = AF_INET;
1103         rtm->rtm_dst_len = dst_len;
1104         rtm->rtm_src_len = 0;
1105         rtm->rtm_tos = tos;
1106         if (tb_id < 256)
1107                 rtm->rtm_table = tb_id;
1108         else
1109                 rtm->rtm_table = RT_TABLE_COMPAT;
1110         if (nla_put_u32(skb, RTA_TABLE, tb_id))
1111                 goto nla_put_failure;
1112         rtm->rtm_type = type;
1113         rtm->rtm_flags = fi->fib_flags;
1114         rtm->rtm_scope = fi->fib_scope;
1115         rtm->rtm_protocol = fi->fib_protocol;
1116
1117         if (rtm->rtm_dst_len &&
1118             nla_put_in_addr(skb, RTA_DST, dst))
1119                 goto nla_put_failure;
1120         if (fi->fib_priority &&
1121             nla_put_u32(skb, RTA_PRIORITY, fi->fib_priority))
1122                 goto nla_put_failure;
1123         if (rtnetlink_put_metrics(skb, fi->fib_metrics) < 0)
1124                 goto nla_put_failure;
1125
1126         if (fi->fib_prefsrc &&
1127             nla_put_in_addr(skb, RTA_PREFSRC, fi->fib_prefsrc))
1128                 goto nla_put_failure;
1129         if (fi->fib_nhs == 1) {
1130                 struct in_device *in_dev;
1131
1132                 if (fi->fib_nh->nh_gw &&
1133                     nla_put_in_addr(skb, RTA_GATEWAY, fi->fib_nh->nh_gw))
1134                         goto nla_put_failure;
1135                 if (fi->fib_nh->nh_oif &&
1136                     nla_put_u32(skb, RTA_OIF, fi->fib_nh->nh_oif))
1137                         goto nla_put_failure;
1138                 if (fi->fib_nh->nh_flags & RTNH_F_LINKDOWN) {
1139                         in_dev = __in_dev_get_rtnl(fi->fib_nh->nh_dev);
1140                         if (in_dev &&
1141                             IN_DEV_IGNORE_ROUTES_WITH_LINKDOWN(in_dev))
1142                                 rtm->rtm_flags |= RTNH_F_DEAD;
1143                 }
1144 #ifdef CONFIG_IP_ROUTE_CLASSID
1145                 if (fi->fib_nh[0].nh_tclassid &&
1146                     nla_put_u32(skb, RTA_FLOW, fi->fib_nh[0].nh_tclassid))
1147                         goto nla_put_failure;
1148 #endif
1149                 if (fi->fib_nh->nh_lwtstate)
1150                         lwtunnel_fill_encap(skb, fi->fib_nh->nh_lwtstate);
1151         }
1152 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1153         if (fi->fib_nhs > 1) {
1154                 struct rtnexthop *rtnh;
1155                 struct nlattr *mp;
1156
1157                 mp = nla_nest_start(skb, RTA_MULTIPATH);
1158                 if (!mp)
1159                         goto nla_put_failure;
1160
1161                 for_nexthops(fi) {
1162                         struct in_device *in_dev;
1163
1164                         rtnh = nla_reserve_nohdr(skb, sizeof(*rtnh));
1165                         if (!rtnh)
1166                                 goto nla_put_failure;
1167
1168                         rtnh->rtnh_flags = nh->nh_flags & 0xFF;
1169                         if (nh->nh_flags & RTNH_F_LINKDOWN) {
1170                                 in_dev = __in_dev_get_rtnl(nh->nh_dev);
1171                                 if (in_dev &&
1172                                     IN_DEV_IGNORE_ROUTES_WITH_LINKDOWN(in_dev))
1173                                         rtnh->rtnh_flags |= RTNH_F_DEAD;
1174                         }
1175                         rtnh->rtnh_hops = nh->nh_weight - 1;
1176                         rtnh->rtnh_ifindex = nh->nh_oif;
1177
1178                         if (nh->nh_gw &&
1179                             nla_put_in_addr(skb, RTA_GATEWAY, nh->nh_gw))
1180                                 goto nla_put_failure;
1181 #ifdef CONFIG_IP_ROUTE_CLASSID
1182                         if (nh->nh_tclassid &&
1183                             nla_put_u32(skb, RTA_FLOW, nh->nh_tclassid))
1184                                 goto nla_put_failure;
1185 #endif
1186                         if (nh->nh_lwtstate)
1187                                 lwtunnel_fill_encap(skb, nh->nh_lwtstate);
1188                         /* length of rtnetlink header + attributes */
1189                         rtnh->rtnh_len = nlmsg_get_pos(skb) - (void *) rtnh;
1190                 } endfor_nexthops(fi);
1191
1192                 nla_nest_end(skb, mp);
1193         }
1194 #endif
1195         nlmsg_end(skb, nlh);
1196         return 0;
1197
1198 nla_put_failure:
1199         nlmsg_cancel(skb, nlh);
1200         return -EMSGSIZE;
1201 }
1202
1203 /*
1204  * Update FIB if:
1205  * - local address disappeared -> we must delete all the entries
1206  *   referring to it.
1207  * - device went down -> we must shutdown all nexthops going via it.
1208  */
1209 int fib_sync_down_addr(struct net *net, __be32 local)
1210 {
1211         int ret = 0;
1212         unsigned int hash = fib_laddr_hashfn(local);
1213         struct hlist_head *head = &fib_info_laddrhash[hash];
1214         struct fib_info *fi;
1215
1216         if (!fib_info_laddrhash || local == 0)
1217                 return 0;
1218
1219         hlist_for_each_entry(fi, head, fib_lhash) {
1220                 if (!net_eq(fi->fib_net, net))
1221                         continue;
1222                 if (fi->fib_prefsrc == local) {
1223                         fi->fib_flags |= RTNH_F_DEAD;
1224                         ret++;
1225                 }
1226         }
1227         return ret;
1228 }
1229
1230 int fib_sync_down_dev(struct net_device *dev, unsigned long event)
1231 {
1232         int ret = 0;
1233         int scope = RT_SCOPE_NOWHERE;
1234         struct fib_info *prev_fi = NULL;
1235         unsigned int hash = fib_devindex_hashfn(dev->ifindex);
1236         struct hlist_head *head = &fib_info_devhash[hash];
1237         struct fib_nh *nh;
1238
1239         if (event == NETDEV_UNREGISTER ||
1240             event == NETDEV_DOWN)
1241                 scope = -1;
1242
1243         hlist_for_each_entry(nh, head, nh_hash) {
1244                 struct fib_info *fi = nh->nh_parent;
1245                 int dead;
1246
1247                 BUG_ON(!fi->fib_nhs);
1248                 if (nh->nh_dev != dev || fi == prev_fi)
1249                         continue;
1250                 prev_fi = fi;
1251                 dead = 0;
1252                 change_nexthops(fi) {
1253                         if (nexthop_nh->nh_flags & RTNH_F_DEAD)
1254                                 dead++;
1255                         else if (nexthop_nh->nh_dev == dev &&
1256                                  nexthop_nh->nh_scope != scope) {
1257                                 switch (event) {
1258                                 case NETDEV_DOWN:
1259                                 case NETDEV_UNREGISTER:
1260                                         nexthop_nh->nh_flags |= RTNH_F_DEAD;
1261                                         /* fall through */
1262                                 case NETDEV_CHANGE:
1263                                         nexthop_nh->nh_flags |= RTNH_F_LINKDOWN;
1264                                         break;
1265                                 }
1266 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1267                                 spin_lock_bh(&fib_multipath_lock);
1268                                 fi->fib_power -= nexthop_nh->nh_power;
1269                                 nexthop_nh->nh_power = 0;
1270                                 spin_unlock_bh(&fib_multipath_lock);
1271 #endif
1272                                 dead++;
1273                         }
1274 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1275                         if (event == NETDEV_UNREGISTER &&
1276                             nexthop_nh->nh_dev == dev) {
1277                                 dead = fi->fib_nhs;
1278                                 break;
1279                         }
1280 #endif
1281                 } endfor_nexthops(fi)
1282                 if (dead == fi->fib_nhs) {
1283                         switch (event) {
1284                         case NETDEV_DOWN:
1285                         case NETDEV_UNREGISTER:
1286                                 fi->fib_flags |= RTNH_F_DEAD;
1287                                 /* fall through */
1288                         case NETDEV_CHANGE:
1289                                 fi->fib_flags |= RTNH_F_LINKDOWN;
1290                                 break;
1291                         }
1292                         ret++;
1293                 }
1294         }
1295
1296         return ret;
1297 }
1298
1299 /* Must be invoked inside of an RCU protected region.  */
1300 void fib_select_default(const struct flowi4 *flp, struct fib_result *res)
1301 {
1302         struct fib_info *fi = NULL, *last_resort = NULL;
1303         struct hlist_head *fa_head = res->fa_head;
1304         struct fib_table *tb = res->table;
1305         u8 slen = 32 - res->prefixlen;
1306         int order = -1, last_idx = -1;
1307         struct fib_alias *fa, *fa1 = NULL;
1308         u32 last_prio = res->fi->fib_priority;
1309         u8 last_tos = 0;
1310
1311         hlist_for_each_entry_rcu(fa, fa_head, fa_list) {
1312                 struct fib_info *next_fi = fa->fa_info;
1313
1314                 if (fa->fa_slen != slen)
1315                         continue;
1316                 if (fa->fa_tos && fa->fa_tos != flp->flowi4_tos)
1317                         continue;
1318                 if (fa->tb_id != tb->tb_id)
1319                         continue;
1320                 if (next_fi->fib_priority > last_prio &&
1321                     fa->fa_tos == last_tos) {
1322                         if (last_tos)
1323                                 continue;
1324                         break;
1325                 }
1326                 if (next_fi->fib_flags & RTNH_F_DEAD)
1327                         continue;
1328                 last_tos = fa->fa_tos;
1329                 last_prio = next_fi->fib_priority;
1330
1331                 if (next_fi->fib_scope != res->scope ||
1332                     fa->fa_type != RTN_UNICAST)
1333                         continue;
1334                 if (!next_fi->fib_nh[0].nh_gw ||
1335                     next_fi->fib_nh[0].nh_scope != RT_SCOPE_LINK)
1336                         continue;
1337
1338                 fib_alias_accessed(fa);
1339
1340                 if (!fi) {
1341                         if (next_fi != res->fi)
1342                                 break;
1343                         fa1 = fa;
1344                 } else if (!fib_detect_death(fi, order, &last_resort,
1345                                              &last_idx, fa1->fa_default)) {
1346                         fib_result_assign(res, fi);
1347                         fa1->fa_default = order;
1348                         goto out;
1349                 }
1350                 fi = next_fi;
1351                 order++;
1352         }
1353
1354         if (order <= 0 || !fi) {
1355                 if (fa1)
1356                         fa1->fa_default = -1;
1357                 goto out;
1358         }
1359
1360         if (!fib_detect_death(fi, order, &last_resort, &last_idx,
1361                               fa1->fa_default)) {
1362                 fib_result_assign(res, fi);
1363                 fa1->fa_default = order;
1364                 goto out;
1365         }
1366
1367         if (last_idx >= 0)
1368                 fib_result_assign(res, last_resort);
1369         fa1->fa_default = last_idx;
1370 out:
1371         return;
1372 }
1373
1374 /*
1375  * Dead device goes up. We wake up dead nexthops.
1376  * It takes sense only on multipath routes.
1377  */
1378 int fib_sync_up(struct net_device *dev, unsigned int nh_flags)
1379 {
1380         struct fib_info *prev_fi;
1381         unsigned int hash;
1382         struct hlist_head *head;
1383         struct fib_nh *nh;
1384         int ret;
1385
1386         if (!(dev->flags & IFF_UP))
1387                 return 0;
1388
1389         prev_fi = NULL;
1390         hash = fib_devindex_hashfn(dev->ifindex);
1391         head = &fib_info_devhash[hash];
1392         ret = 0;
1393
1394         hlist_for_each_entry(nh, head, nh_hash) {
1395                 struct fib_info *fi = nh->nh_parent;
1396                 int alive;
1397
1398                 BUG_ON(!fi->fib_nhs);
1399                 if (nh->nh_dev != dev || fi == prev_fi)
1400                         continue;
1401
1402                 prev_fi = fi;
1403                 alive = 0;
1404                 change_nexthops(fi) {
1405                         if (!(nexthop_nh->nh_flags & nh_flags)) {
1406                                 alive++;
1407                                 continue;
1408                         }
1409                         if (!nexthop_nh->nh_dev ||
1410                             !(nexthop_nh->nh_dev->flags & IFF_UP))
1411                                 continue;
1412                         if (nexthop_nh->nh_dev != dev ||
1413                             !__in_dev_get_rtnl(dev))
1414                                 continue;
1415                         alive++;
1416 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1417                         spin_lock_bh(&fib_multipath_lock);
1418                         nexthop_nh->nh_power = 0;
1419                         nexthop_nh->nh_flags &= ~nh_flags;
1420                         spin_unlock_bh(&fib_multipath_lock);
1421 #else
1422                         nexthop_nh->nh_flags &= ~nh_flags;
1423 #endif
1424                 } endfor_nexthops(fi)
1425
1426                 if (alive > 0) {
1427                         fi->fib_flags &= ~nh_flags;
1428                         ret++;
1429                 }
1430         }
1431
1432         return ret;
1433 }
1434
1435 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1436
1437 /*
1438  * The algorithm is suboptimal, but it provides really
1439  * fair weighted route distribution.
1440  */
1441 void fib_select_multipath(struct fib_result *res)
1442 {
1443         struct fib_info *fi = res->fi;
1444         struct in_device *in_dev;
1445         int w;
1446
1447         spin_lock_bh(&fib_multipath_lock);
1448         if (fi->fib_power <= 0) {
1449                 int power = 0;
1450                 change_nexthops(fi) {
1451                         in_dev = __in_dev_get_rcu(nexthop_nh->nh_dev);
1452                         if (nexthop_nh->nh_flags & RTNH_F_DEAD)
1453                                 continue;
1454                         if (in_dev &&
1455                             IN_DEV_IGNORE_ROUTES_WITH_LINKDOWN(in_dev) &&
1456                             nexthop_nh->nh_flags & RTNH_F_LINKDOWN)
1457                                 continue;
1458                         power += nexthop_nh->nh_weight;
1459                         nexthop_nh->nh_power = nexthop_nh->nh_weight;
1460                 } endfor_nexthops(fi);
1461                 fi->fib_power = power;
1462                 if (power <= 0) {
1463                         spin_unlock_bh(&fib_multipath_lock);
1464                         /* Race condition: route has just become dead. */
1465                         res->nh_sel = 0;
1466                         return;
1467                 }
1468         }
1469
1470
1471         /* w should be random number [0..fi->fib_power-1],
1472          * it is pretty bad approximation.
1473          */
1474
1475         w = jiffies % fi->fib_power;
1476
1477         change_nexthops(fi) {
1478                 if (!(nexthop_nh->nh_flags & RTNH_F_DEAD) &&
1479                     nexthop_nh->nh_power) {
1480                         w -= nexthop_nh->nh_power;
1481                         if (w <= 0) {
1482                                 nexthop_nh->nh_power--;
1483                                 fi->fib_power--;
1484                                 res->nh_sel = nhsel;
1485                                 spin_unlock_bh(&fib_multipath_lock);
1486                                 return;
1487                         }
1488                 }
1489         } endfor_nexthops(fi);
1490
1491         /* Race condition: route has just become dead. */
1492         res->nh_sel = 0;
1493         spin_unlock_bh(&fib_multipath_lock);
1494 }
1495 #endif