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
  46 #include "fib_lookup.h"
  47
  48 static DEFINE_SPINLOCK(fib_info_lock);
  49 static struct hlist_head *fib_info_hash;
  50 static struct hlist_head *fib_info_laddrhash;
  51 static unsigned int fib_info_hash_size;
  52 static unsigned int fib_info_cnt;
  53
  54 #define DEVINDEX_HASHBITS 8
  55 #define DEVINDEX_HASHSIZE (1U << DEVINDEX_HASHBITS)
  56 static struct hlist_head fib_info_devhash[DEVINDEX_HASHSIZE];
  57
  58 #ifdef CONFIG_IP_ROUTE_MULTIPATH
  59
  60 static DEFINE_SPINLOCK(fib_multipath_lock);
  61
  62 #define for_nexthops(fi) {                                              \
  63         int nhsel; const struct fib_nh *nh;                             \
  64         for (nhsel = 0, nh = (fi)->fib_nh;                              \
  65              nhsel < (fi)->fib_nhs;                                     \
  66              nh++, nhsel++)
  67
  68 #define change_nexthops(fi) {                                           \
  69         int nhsel; struct fib_nh *nexthop_nh;                           \
  70         for (nhsel = 0, nexthop_nh = (struct fib_nh *)((fi)->fib_nh);   \
  71              nhsel < (fi)->fib_nhs;                                     \
  72              nexthop_nh++, nhsel++)
  73
  74 #else /* CONFIG_IP_ROUTE_MULTIPATH */
  75
  76 /* Hope, that gcc will optimize it to get rid of dummy loop */
  77
  78 #define for_nexthops(fi) {                                              \
  79         int nhsel; const struct fib_nh *nh = (fi)->fib_nh;              \
  80         for (nhsel = 0; nhsel < 1; nhsel++)
  81
  82 #define change_nexthops(fi) {                                           \
  83         int nhsel;                                                      \
  84         struct fib_nh *nexthop_nh = (struct fib_nh *)((fi)->fib_nh);    \
  85         for (nhsel = 0; nhsel < 1; nhsel++)
  86
  87 #endif /* CONFIG_IP_ROUTE_MULTIPATH */
  88
  89 #define endfor_nexthops(fi) }
  90
  91
  92 const struct fib_prop fib_props[RTN_MAX + 1] = {
  93         [RTN_UNSPEC] = {
  94                 .error  = 0,
  95                 .scope  = RT_SCOPE_NOWHERE,
  96         },
  97         [RTN_UNICAST] = {
  98                 .error  = 0,
  99                 .scope  = RT_SCOPE_UNIVERSE,
 100         },
 101         [RTN_LOCAL] = {
 102                 .error  = 0,
 103                 .scope  = RT_SCOPE_HOST,
 104         },
 105         [RTN_BROADCAST] = {
 106                 .error  = 0,
 107                 .scope  = RT_SCOPE_LINK,
 108         },
 109         [RTN_ANYCAST] = {
 110                 .error  = 0,
 111                 .scope  = RT_SCOPE_LINK,
 112         },
 113         [RTN_MULTICAST] = {
 114                 .error  = 0,
 115                 .scope  = RT_SCOPE_UNIVERSE,
 116         },
 117         [RTN_BLACKHOLE] = {
 118                 .error  = -EINVAL,
 119                 .scope  = RT_SCOPE_UNIVERSE,
 120         },
 121         [RTN_UNREACHABLE] = {
 122                 .error  = -EHOSTUNREACH,
 123                 .scope  = RT_SCOPE_UNIVERSE,
 124         },
 125         [RTN_PROHIBIT] = {
 126                 .error  = -EACCES,
 127                 .scope  = RT_SCOPE_UNIVERSE,
 128         },
 129         [RTN_THROW] = {
 130                 .error  = -EAGAIN,
 131                 .scope  = RT_SCOPE_UNIVERSE,
 132         },
 133         [RTN_NAT] = {
 134                 .error  = -EINVAL,
 135                 .scope  = RT_SCOPE_NOWHERE,
 136         },
 137         [RTN_XRESOLVE] = {
 138                 .error  = -EINVAL,
 139                 .scope  = RT_SCOPE_NOWHERE,
 140         },
 141 };
 142
 143 static void rt_fibinfo_free(struct rtable __rcu **rtp)
 144 {
 145         struct rtable *rt = rcu_dereference_protected(*rtp, 1);
 146
 147         if (!rt)
 148                 return;
 149
 150         /* Not even needed : RCU_INIT_POINTER(*rtp, NULL);
 151          * because we waited an RCU grace period before calling
 152          * free_fib_info_rcu()
 153          */
 154
 155         dst_free(&rt->dst);
 156 }
 157
 158 static void free_nh_exceptions(struct fib_nh *nh)
 159 {
 160         struct fnhe_hash_bucket *hash;
 161         int i;
 162
 163         hash = rcu_dereference_protected(nh->nh_exceptions, 1);
 164         if (!hash)
 165                 return;
 166         for (i = 0; i < FNHE_HASH_SIZE; i++) {
 167                 struct fib_nh_exception *fnhe;
 168
 169                 fnhe = rcu_dereference_protected(hash[i].chain, 1);
 170                 while (fnhe) {
 171                         struct fib_nh_exception *next;
 172
 173                         next = rcu_dereference_protected(fnhe->fnhe_next, 1);
 174
 175                         rt_fibinfo_free(&fnhe->fnhe_rth_input);
 176                         rt_fibinfo_free(&fnhe->fnhe_rth_output);
 177
 178                         kfree(fnhe);
 179
 180                         fnhe = next;
 181                 }
 182         }
 183         kfree(hash);
 184 }
 185
 186 static void rt_fibinfo_free_cpus(struct rtable __rcu * __percpu *rtp)
 187 {
 188         int cpu;
 189
 190         if (!rtp)
 191                 return;
 192
 193         for_each_possible_cpu(cpu) {
 194                 struct rtable *rt;
 195
 196                 rt = rcu_dereference_protected(*per_cpu_ptr(rtp, cpu), 1);
 197                 if (rt)
 198                         dst_free(&rt->dst);
 199         }
 200         free_percpu(rtp);
 201 }
 202
 203 /* Release a nexthop info record */
 204 static void free_fib_info_rcu(struct rcu_head *head)
 205 {
 206         struct fib_info *fi = container_of(head, struct fib_info, rcu);
 207
 208         change_nexthops(fi) {
 209                 if (nexthop_nh->nh_dev)
 210                         dev_put(nexthop_nh->nh_dev);
 211                 free_nh_exceptions(nexthop_nh);
 212                 rt_fibinfo_free_cpus(nexthop_nh->nh_pcpu_rth_output);
 213                 rt_fibinfo_free(&nexthop_nh->nh_rth_input);
 214         } endfor_nexthops(fi);
 215
 216         release_net(fi->fib_net);
 217         if (fi->fib_metrics != (u32 *) dst_default_metrics)
 218                 kfree(fi->fib_metrics);
 219         kfree(fi);
 220 }
 221
 222 void free_fib_info(struct fib_info *fi)
 223 {
 224         if (fi->fib_dead == 0) {
 225                 pr_warn("Freeing alive fib_info %p\n", fi);
 226                 return;
 227         }
 228         fib_info_cnt--;
 229 #ifdef CONFIG_IP_ROUTE_CLASSID
 230         change_nexthops(fi) {
 231                 if (nexthop_nh->nh_tclassid)
 232                         fi->fib_net->ipv4.fib_num_tclassid_users--;
 233         } endfor_nexthops(fi);
 234 #endif
 235         call_rcu(&fi->rcu, free_fib_info_rcu);
 236 }
 237
 238 void fib_release_info(struct fib_info *fi)
 239 {
 240         spin_lock_bh(&fib_info_lock);
 241         if (fi && --fi->fib_treeref == 0) {
 242                 hlist_del(&fi->fib_hash);
 243                 if (fi->fib_prefsrc)
 244                         hlist_del(&fi->fib_lhash);
 245                 change_nexthops(fi) {
 246                         if (!nexthop_nh->nh_dev)
 247                                 continue;
 248                         hlist_del(&nexthop_nh->nh_hash);
 249                 } endfor_nexthops(fi)
 250                 fi->fib_dead = 1;
 251                 fib_info_put(fi);
 252         }
 253         spin_unlock_bh(&fib_info_lock);
 254 }
 255
 256 static inline int nh_comp(const struct fib_info *fi, const struct fib_info *ofi)
 257 {
 258         const struct fib_nh *onh = ofi->fib_nh;
 259
 260         for_nexthops(fi) {
 261                 if (nh->nh_oif != onh->nh_oif ||
 262                     nh->nh_gw  != onh->nh_gw ||
 263                     nh->nh_scope != onh->nh_scope ||
 264 #ifdef CONFIG_IP_ROUTE_MULTIPATH
 265                     nh->nh_weight != onh->nh_weight ||
 266 #endif
 267 #ifdef CONFIG_IP_ROUTE_CLASSID
 268                     nh->nh_tclassid != onh->nh_tclassid ||
 269 #endif
 270                     ((nh->nh_flags ^ onh->nh_flags) & ~RTNH_F_DEAD))
 271                         return -1;
 272                 onh++;
 273         } endfor_nexthops(fi);
 274         return 0;
 275 }
 276
 277 static inline unsigned int fib_devindex_hashfn(unsigned int val)
 278 {
 279         unsigned int mask = DEVINDEX_HASHSIZE - 1;
 280
 281         return (val ^
 282                 (val >> DEVINDEX_HASHBITS) ^
 283                 (val >> (DEVINDEX_HASHBITS * 2))) & mask;
 284 }
 285
 286 static inline unsigned int fib_info_hashfn(const struct fib_info *fi)
 287 {
 288         unsigned int mask = (fib_info_hash_size - 1);
 289         unsigned int val = fi->fib_nhs;
 290
 291         val ^= (fi->fib_protocol << 8) | fi->fib_scope;
 292         val ^= (__force u32)fi->fib_prefsrc;
 293         val ^= fi->fib_priority;
 294         for_nexthops(fi) {
 295                 val ^= fib_devindex_hashfn(nh->nh_oif);
 296         } endfor_nexthops(fi)
 297
 298         return (val ^ (val >> 7) ^ (val >> 12)) & mask;
 299 }
 300
 301 static struct fib_info *fib_find_info(const struct fib_info *nfi)
 302 {
 303         struct hlist_head *head;
 304         struct fib_info *fi;
 305         unsigned int hash;
 306
 307         hash = fib_info_hashfn(nfi);
 308         head = &fib_info_hash[hash];
 309
 310         hlist_for_each_entry(fi, head, fib_hash) {
 311                 if (!net_eq(fi->fib_net, nfi->fib_net))
 312                         continue;
 313                 if (fi->fib_nhs != nfi->fib_nhs)
 314                         continue;
 315                 if (nfi->fib_protocol == fi->fib_protocol &&
 316                     nfi->fib_scope == fi->fib_scope &&
 317                     nfi->fib_prefsrc == fi->fib_prefsrc &&
 318                     nfi->fib_priority == fi->fib_priority &&
 319                     nfi->fib_type == fi->fib_type &&
 320                     memcmp(nfi->fib_metrics, fi->fib_metrics,
 321                            sizeof(u32) * RTAX_MAX) == 0 &&
 322                     ((nfi->fib_flags ^ fi->fib_flags) & ~RTNH_F_DEAD) == 0 &&
 323                     (nfi->fib_nhs == 0 || nh_comp(fi, nfi) == 0))
 324                         return fi;
 325         }
 326
 327         return NULL;
 328 }
 329
 330 /* Check, that the gateway is already configured.
 331  * Used only by redirect accept routine.
 332  */
 333 int ip_fib_check_default(__be32 gw, struct net_device *dev)
 334 {
 335         struct hlist_head *head;
 336         struct fib_nh *nh;
 337         unsigned int hash;
 338
 339         spin_lock(&fib_info_lock);
 340
 341         hash = fib_devindex_hashfn(dev->ifindex);
 342         head = &fib_info_devhash[hash];
 343         hlist_for_each_entry(nh, head, nh_hash) {
 344                 if (nh->nh_dev == dev &&
 345                     nh->nh_gw == gw &&
 346                     !(nh->nh_flags & RTNH_F_DEAD)) {
 347                         spin_unlock(&fib_info_lock);
 348                         return 0;
 349                 }
 350         }
 351
 352         spin_unlock(&fib_info_lock);
 353
 354         return -1;
 355 }
 356
 357 static inline size_t fib_nlmsg_size(struct fib_info *fi)
 358 {
 359         size_t payload = NLMSG_ALIGN(sizeof(struct rtmsg))
 360                          + nla_total_size(4) /* RTA_TABLE */
 361                          + nla_total_size(4) /* RTA_DST */
 362                          + nla_total_size(4) /* RTA_PRIORITY */
 363                          + nla_total_size(4) /* RTA_PREFSRC */
 364                          + nla_total_size(TCP_CA_NAME_MAX); /* RTAX_CC_ALGO */
 365
 366         /* space for nested metrics */
 367         payload += nla_total_size((RTAX_MAX * nla_total_size(4)));
 368
 369         if (fi->fib_nhs) {
 370                 /* Also handles the special case fib_nhs == 1 */
 371
 372                 /* each nexthop is packed in an attribute */
 373                 size_t nhsize = nla_total_size(sizeof(struct rtnexthop));
 374
 375                 /* may contain flow and gateway attribute */
 376                 nhsize += 2 * nla_total_size(4);
 377
 378                 /* all nexthops are packed in a nested attribute */
 379                 payload += nla_total_size(fi->fib_nhs * nhsize);
 380         }
 381
 382         return payload;
 383 }
 384
 385 void rtmsg_fib(int event, __be32 key, struct fib_alias *fa,
 386                int dst_len, u32 tb_id, const struct nl_info *info,
 387                unsigned int nlm_flags)
 388 {
 389         struct sk_buff *skb;
 390         u32 seq = info->nlh ? info->nlh->nlmsg_seq : 0;
 391         int err = -ENOBUFS;
 392
 393         skb = nlmsg_new(fib_nlmsg_size(fa->fa_info), GFP_KERNEL);
 394         if (skb == NULL)
 395                 goto errout;
 396
 397         err = fib_dump_info(skb, info->portid, seq, event, tb_id,
 398                             fa->fa_type, key, dst_len,
 399                             fa->fa_tos, fa->fa_info, nlm_flags);
 400         if (err < 0) {
 401                 /* -EMSGSIZE implies BUG in fib_nlmsg_size() */
 402                 WARN_ON(err == -EMSGSIZE);
 403                 kfree_skb(skb);
 404                 goto errout;
 405         }
 406         rtnl_notify(skb, info->nl_net, info->portid, RTNLGRP_IPV4_ROUTE,
 407                     info->nlh, GFP_KERNEL);
 408         return;
 409 errout:
 410         if (err < 0)
 411                 rtnl_set_sk_err(info->nl_net, RTNLGRP_IPV4_ROUTE, err);
 412 }
 413
 414 static int fib_detect_death(struct fib_info *fi, int order,
 415                             struct fib_info **last_resort, int *last_idx,
 416                             int dflt)
 417 {
 418         struct neighbour *n;
 419         int state = NUD_NONE;
 420
 421         n = neigh_lookup(&arp_tbl, &fi->fib_nh[0].nh_gw, fi->fib_dev);
 422         if (n) {
 423                 state = n->nud_state;
 424                 neigh_release(n);
 425         }
 426         if (state == NUD_REACHABLE)
 427                 return 0;
 428         if ((state & NUD_VALID) && order != dflt)
 429                 return 0;
 430         if ((state & NUD_VALID) ||
 431             (*last_idx < 0 && order > dflt)) {
 432                 *last_resort = fi;
 433                 *last_idx = order;
 434         }
 435         return 1;
 436 }
 437
 438 #ifdef CONFIG_IP_ROUTE_MULTIPATH
 439
 440 static int fib_count_nexthops(struct rtnexthop *rtnh, int remaining)
 441 {
 442         int nhs = 0;
 443
 444         while (rtnh_ok(rtnh, remaining)) {
 445                 nhs++;
 446                 rtnh = rtnh_next(rtnh, &remaining);
 447         }
 448
 449         /* leftover implies invalid nexthop configuration, discard it */
 450         return remaining > 0 ? 0 : nhs;
 451 }
 452
 453 static int fib_get_nhs(struct fib_info *fi, struct rtnexthop *rtnh,
 454                        int remaining, struct fib_config *cfg)
 455 {
 456         change_nexthops(fi) {
 457                 int attrlen;
 458
 459                 if (!rtnh_ok(rtnh, remaining))
 460                         return -EINVAL;
 461
 462                 nexthop_nh->nh_flags =
 463                         (cfg->fc_flags & ~0xFF) | rtnh->rtnh_flags;
 464                 nexthop_nh->nh_oif = rtnh->rtnh_ifindex;
 465                 nexthop_nh->nh_weight = rtnh->rtnh_hops + 1;
 466
 467                 attrlen = rtnh_attrlen(rtnh);
 468                 if (attrlen > 0) {
 469                         struct nlattr *nla, *attrs = rtnh_attrs(rtnh);
 470
 471                         nla = nla_find(attrs, attrlen, RTA_GATEWAY);
 472                         nexthop_nh->nh_gw = nla ? nla_get_be32(nla) : 0;
 473 #ifdef CONFIG_IP_ROUTE_CLASSID
 474                         nla = nla_find(attrs, attrlen, RTA_FLOW);
 475                         nexthop_nh->nh_tclassid = nla ? nla_get_u32(nla) : 0;
 476                         if (nexthop_nh->nh_tclassid)
 477                                 fi->fib_net->ipv4.fib_num_tclassid_users++;
 478 #endif
 479                 }
 480
 481                 rtnh = rtnh_next(rtnh, &remaining);
 482         } endfor_nexthops(fi);
 483
 484         return 0;
 485 }
 486
 487 #endif
 488
 489 int fib_nh_match(struct fib_config *cfg, struct fib_info *fi)
 490 {
 491 #ifdef CONFIG_IP_ROUTE_MULTIPATH
 492         struct rtnexthop *rtnh;
 493         int remaining;
 494 #endif
 495
 496         if (cfg->fc_priority && cfg->fc_priority != fi->fib_priority)
 497                 return 1;
 498
 499         if (cfg->fc_oif || cfg->fc_gw) {
 500                 if ((!cfg->fc_oif || cfg->fc_oif == fi->fib_nh->nh_oif) &&
 501                     (!cfg->fc_gw  || cfg->fc_gw == fi->fib_nh->nh_gw))
 502                         return 0;
 503                 return 1;
 504         }
 505
 506 #ifdef CONFIG_IP_ROUTE_MULTIPATH
 507         if (cfg->fc_mp == NULL)
 508                 return 0;
 509
 510         rtnh = cfg->fc_mp;
 511         remaining = cfg->fc_mp_len;
 512
 513         for_nexthops(fi) {
 514                 int attrlen;
 515
 516                 if (!rtnh_ok(rtnh, remaining))
 517                         return -EINVAL;
 518
 519                 if (rtnh->rtnh_ifindex && rtnh->rtnh_ifindex != nh->nh_oif)
 520                         return 1;
 521
 522                 attrlen = rtnh_attrlen(rtnh);
 523                 if (attrlen > 0) {
 524                         struct nlattr *nla, *attrs = rtnh_attrs(rtnh);
 525
 526                         nla = nla_find(attrs, attrlen, RTA_GATEWAY);
 527                         if (nla && nla_get_be32(nla) != nh->nh_gw)
 528                                 return 1;
 529 #ifdef CONFIG_IP_ROUTE_CLASSID
 530                         nla = nla_find(attrs, attrlen, RTA_FLOW);
 531                         if (nla && nla_get_u32(nla) != nh->nh_tclassid)
 532                                 return 1;
 533 #endif
 534                 }
 535
 536                 rtnh = rtnh_next(rtnh, &remaining);
 537         } endfor_nexthops(fi);
 538 #endif
 539         return 0;
 540 }
 541
 542
 543 /*
 544  * Picture
 545  * -------
 546  *
 547  * Semantics of nexthop is very messy by historical reasons.
 548  * We have to take into account, that:
 549  * a) gateway can be actually local interface address,
 550  *    so that gatewayed route is direct.
 551  * b) gateway must be on-link address, possibly
 552  *    described not by an ifaddr, but also by a direct route.
 553  * c) If both gateway and interface are specified, they should not
 554  *    contradict.
 555  * d) If we use tunnel routes, gateway could be not on-link.
 556  *
 557  * Attempt to reconcile all of these (alas, self-contradictory) conditions
 558  * results in pretty ugly and hairy code with obscure logic.
 559  *
 560  * I chose to generalized it instead, so that the size
 561  * of code does not increase practically, but it becomes
 562  * much more general.
 563  * Every prefix is assigned a "scope" value: "host" is local address,
 564  * "link" is direct route,
 565  * [ ... "site" ... "interior" ... ]
 566  * and "universe" is true gateway route with global meaning.
 567  *
 568  * Every prefix refers to a set of "nexthop"s (gw, oif),
 569  * where gw must have narrower scope. This recursion stops
 570  * when gw has LOCAL scope or if "nexthop" is declared ONLINK,
 571  * which means that gw is forced to be on link.
 572  *
 573  * Code is still hairy, but now it is apparently logically
 574  * consistent and very flexible. F.e. as by-product it allows
 575  * to co-exists in peace independent exterior and interior
 576  * routing processes.
 577  *
 578  * Normally it looks as following.
 579  *
 580  * {universe prefix}  -> (gw, oif) [scope link]
 581  *                |
 582  *                |-> {link prefix} -> (gw, oif) [scope local]
 583  *                                      |
 584  *                                      |-> {local prefix} (terminal node)
 585  */
 586 static int fib_check_nh(struct fib_config *cfg, struct fib_info *fi,
 587                         struct fib_nh *nh)
 588 {
 589         int err;
 590         struct net *net;
 591         struct net_device *dev;
 592
 593         net = cfg->fc_nlinfo.nl_net;
 594         if (nh->nh_gw) {
 595                 struct fib_result res;
 596
 597                 if (nh->nh_flags & RTNH_F_ONLINK) {
 598
 599                         if (cfg->fc_scope >= RT_SCOPE_LINK)
 600                                 return -EINVAL;
 601                         if (inet_addr_type(net, nh->nh_gw) != RTN_UNICAST)
 602                                 return -EINVAL;
 603                         dev = __dev_get_by_index(net, nh->nh_oif);
 604                         if (!dev)
 605                                 return -ENODEV;
 606                         if (!(dev->flags & IFF_UP))
 607                                 return -ENETDOWN;
 608                         nh->nh_dev = dev;
 609                         dev_hold(dev);
 610                         nh->nh_scope = RT_SCOPE_LINK;
 611                         return 0;
 612                 }
 613                 rcu_read_lock();
 614                 {
 615                         struct flowi4 fl4 = {
 616                                 .daddr = nh->nh_gw,
 617                                 .flowi4_scope = cfg->fc_scope + 1,
 618                                 .flowi4_oif = nh->nh_oif,
 619                                 .flowi4_iif = LOOPBACK_IFINDEX,
 620                         };
 621
 622                         /* It is not necessary, but requires a bit of thinking */
 623                         if (fl4.flowi4_scope < RT_SCOPE_LINK)
 624                                 fl4.flowi4_scope = RT_SCOPE_LINK;
 625                         err = fib_lookup(net, &fl4, &res);
 626                         if (err) {
 627                                 rcu_read_unlock();
 628                                 return err;
 629                         }
 630                 }
 631                 err = -EINVAL;
 632                 if (res.type != RTN_UNICAST && res.type != RTN_LOCAL)
 633                         goto out;
 634                 nh->nh_scope = res.scope;
 635                 nh->nh_oif = FIB_RES_OIF(res);
 636                 nh->nh_dev = dev = FIB_RES_DEV(res);
 637                 if (!dev)
 638                         goto out;
 639                 dev_hold(dev);
 640                 err = (dev->flags & IFF_UP) ? 0 : -ENETDOWN;
 641         } else {
 642                 struct in_device *in_dev;
 643
 644                 if (nh->nh_flags & (RTNH_F_PERVASIVE | RTNH_F_ONLINK))
 645                         return -EINVAL;
 646
 647                 rcu_read_lock();
 648                 err = -ENODEV;
 649                 in_dev = inetdev_by_index(net, nh->nh_oif);
 650                 if (in_dev == NULL)
 651                         goto out;
 652                 err = -ENETDOWN;
 653                 if (!(in_dev->dev->flags & IFF_UP))
 654                         goto out;
 655                 nh->nh_dev = in_dev->dev;
 656                 dev_hold(nh->nh_dev);
 657                 nh->nh_scope = RT_SCOPE_HOST;
 658                 err = 0;
 659         }
 660 out:
 661         rcu_read_unlock();
 662         return err;
 663 }
 664
 665 static inline unsigned int fib_laddr_hashfn(__be32 val)
 666 {
 667         unsigned int mask = (fib_info_hash_size - 1);
 668
 669         return ((__force u32)val ^
 670                 ((__force u32)val >> 7) ^
 671                 ((__force u32)val >> 14)) & mask;
 672 }
 673
 674 static struct hlist_head *fib_info_hash_alloc(int bytes)
 675 {
 676         if (bytes <= PAGE_SIZE)
 677                 return kzalloc(bytes, GFP_KERNEL);
 678         else
 679                 return (struct hlist_head *)
 680                         __get_free_pages(GFP_KERNEL | __GFP_ZERO,
 681                                          get_order(bytes));
 682 }
 683
 684 static void fib_info_hash_free(struct hlist_head *hash, int bytes)
 685 {
 686         if (!hash)
 687                 return;
 688
 689         if (bytes <= PAGE_SIZE)
 690                 kfree(hash);
 691         else
 692                 free_pages((unsigned long) hash, get_order(bytes));
 693 }
 694
 695 static void fib_info_hash_move(struct hlist_head *new_info_hash,
 696                                struct hlist_head *new_laddrhash,
 697                                unsigned int new_size)
 698 {
 699         struct hlist_head *old_info_hash, *old_laddrhash;
 700         unsigned int old_size = fib_info_hash_size;
 701         unsigned int i, bytes;
 702
 703         spin_lock_bh(&fib_info_lock);
 704         old_info_hash = fib_info_hash;
 705         old_laddrhash = fib_info_laddrhash;
 706         fib_info_hash_size = new_size;
 707
 708         for (i = 0; i < old_size; i++) {
 709                 struct hlist_head *head = &fib_info_hash[i];
 710                 struct hlist_node *n;
 711                 struct fib_info *fi;
 712
 713                 hlist_for_each_entry_safe(fi, n, head, fib_hash) {
 714                         struct hlist_head *dest;
 715                         unsigned int new_hash;
 716
 717                         hlist_del(&fi->fib_hash);
 718
 719                         new_hash = fib_info_hashfn(fi);
 720                         dest = &new_info_hash[new_hash];
 721                         hlist_add_head(&fi->fib_hash, dest);
 722                 }
 723         }
 724         fib_info_hash = new_info_hash;
 725
 726         for (i = 0; i < old_size; i++) {
 727                 struct hlist_head *lhead = &fib_info_laddrhash[i];
 728                 struct hlist_node *n;
 729                 struct fib_info *fi;
 730
 731                 hlist_for_each_entry_safe(fi, n, lhead, fib_lhash) {
 732                         struct hlist_head *ldest;
 733                         unsigned int new_hash;
 734
 735                         hlist_del(&fi->fib_lhash);
 736
 737                         new_hash = fib_laddr_hashfn(fi->fib_prefsrc);
 738                         ldest = &new_laddrhash[new_hash];
 739                         hlist_add_head(&fi->fib_lhash, ldest);
 740                 }
 741         }
 742         fib_info_laddrhash = new_laddrhash;
 743
 744         spin_unlock_bh(&fib_info_lock);
 745
 746         bytes = old_size * sizeof(struct hlist_head *);
 747         fib_info_hash_free(old_info_hash, bytes);
 748         fib_info_hash_free(old_laddrhash, bytes);
 749 }
 750
 751 __be32 fib_info_update_nh_saddr(struct net *net, struct fib_nh *nh)
 752 {
 753         nh->nh_saddr = inet_select_addr(nh->nh_dev,
 754                                         nh->nh_gw,
 755                                         nh->nh_parent->fib_scope);
 756         nh->nh_saddr_genid = atomic_read(&net->ipv4.dev_addr_genid);
 757
 758         return nh->nh_saddr;
 759 }
 760
 761 struct fib_info *fib_create_info(struct fib_config *cfg)
 762 {
 763         int err;
 764         struct fib_info *fi = NULL;
 765         struct fib_info *ofi;
 766         int nhs = 1;
 767         struct net *net = cfg->fc_nlinfo.nl_net;
 768
 769         if (cfg->fc_type > RTN_MAX)
 770                 goto err_inval;
 771
 772         /* Fast check to catch the most weird cases */
 773         if (fib_props[cfg->fc_type].scope > cfg->fc_scope)
 774                 goto err_inval;
 775
 776 #ifdef CONFIG_IP_ROUTE_MULTIPATH
 777         if (cfg->fc_mp) {
 778                 nhs = fib_count_nexthops(cfg->fc_mp, cfg->fc_mp_len);
 779                 if (nhs == 0)
 780                         goto err_inval;
 781         }
 782 #endif
 783
 784         err = -ENOBUFS;
 785         if (fib_info_cnt >= fib_info_hash_size) {
 786                 unsigned int new_size = fib_info_hash_size << 1;
 787                 struct hlist_head *new_info_hash;
 788                 struct hlist_head *new_laddrhash;
 789                 unsigned int bytes;
 790
 791                 if (!new_size)
 792                         new_size = 16;
 793                 bytes = new_size * sizeof(struct hlist_head *);
 794                 new_info_hash = fib_info_hash_alloc(bytes);
 795                 new_laddrhash = fib_info_hash_alloc(bytes);
 796                 if (!new_info_hash || !new_laddrhash) {
 797                         fib_info_hash_free(new_info_hash, bytes);
 798                         fib_info_hash_free(new_laddrhash, bytes);
 799                 } else
 800                         fib_info_hash_move(new_info_hash, new_laddrhash, new_size);
 801
 802                 if (!fib_info_hash_size)
 803                         goto failure;
 804         }
 805
 806         fi = kzalloc(sizeof(*fi)+nhs*sizeof(struct fib_nh), GFP_KERNEL);
 807         if (fi == NULL)
 808                 goto failure;
 809         fib_info_cnt++;
 810         if (cfg->fc_mx) {
 811                 fi->fib_metrics = kzalloc(sizeof(u32) * RTAX_MAX, GFP_KERNEL);
 812                 if (!fi->fib_metrics)
 813                         goto failure;
 814         } else
 815                 fi->fib_metrics = (u32 *) dst_default_metrics;
 816
 817         fi->fib_net = hold_net(net);
 818         fi->fib_protocol = cfg->fc_protocol;
 819         fi->fib_scope = cfg->fc_scope;
 820         fi->fib_flags = cfg->fc_flags;
 821         fi->fib_priority = cfg->fc_priority;
 822         fi->fib_prefsrc = cfg->fc_prefsrc;
 823         fi->fib_type = cfg->fc_type;
 824
 825         fi->fib_nhs = nhs;
 826         change_nexthops(fi) {
 827                 nexthop_nh->nh_parent = fi;
 828                 nexthop_nh->nh_pcpu_rth_output = alloc_percpu(struct rtable __rcu *);
 829                 if (!nexthop_nh->nh_pcpu_rth_output)
 830                         goto failure;
 831         } endfor_nexthops(fi)
 832
 833         if (cfg->fc_mx) {
 834                 struct nlattr *nla;
 835                 int remaining;
 836
 837                 nla_for_each_attr(nla, cfg->fc_mx, cfg->fc_mx_len, remaining) {
 838                         int type = nla_type(nla);
 839
 840                         if (type) {
 841                                 u32 val;
 842
 843                                 if (type > RTAX_MAX)
 844                                         goto err_inval;
 845                                 if (type == RTAX_CC_ALGO) {
 846                                         char tmp[TCP_CA_NAME_MAX];
 847
 848                                         nla_strlcpy(tmp, nla, sizeof(tmp));
 849                                         val = tcp_ca_get_key_by_name(tmp);
 850                                         if (val == TCP_CA_UNSPEC)
 851                                                 goto err_inval;
 852                                 } else {
 853                                         val = nla_get_u32(nla);
 854                                 }
 855                                 if (type == RTAX_ADVMSS && val > 65535 - 40)
 856                                         val = 65535 - 40;
 857                                 if (type == RTAX_MTU && val > 65535 - 15)
 858                                         val = 65535 - 15;
 859                                 fi->fib_metrics[type - 1] = val;
 860                         }
 861                 }
 862         }
 863
 864         if (cfg->fc_mp) {
 865 #ifdef CONFIG_IP_ROUTE_MULTIPATH
 866                 err = fib_get_nhs(fi, cfg->fc_mp, cfg->fc_mp_len, cfg);
 867                 if (err != 0)
 868                         goto failure;
 869                 if (cfg->fc_oif && fi->fib_nh->nh_oif != cfg->fc_oif)
 870                         goto err_inval;
 871                 if (cfg->fc_gw && fi->fib_nh->nh_gw != cfg->fc_gw)
 872                         goto err_inval;
 873 #ifdef CONFIG_IP_ROUTE_CLASSID
 874                 if (cfg->fc_flow && fi->fib_nh->nh_tclassid != cfg->fc_flow)
 875                         goto err_inval;
 876 #endif
 877 #else
 878                 goto err_inval;
 879 #endif
 880         } else {
 881                 struct fib_nh *nh = fi->fib_nh;
 882
 883                 nh->nh_oif = cfg->fc_oif;
 884                 nh->nh_gw = cfg->fc_gw;
 885                 nh->nh_flags = cfg->fc_flags;
 886 #ifdef CONFIG_IP_ROUTE_CLASSID
 887                 nh->nh_tclassid = cfg->fc_flow;
 888                 if (nh->nh_tclassid)
 889                         fi->fib_net->ipv4.fib_num_tclassid_users++;
 890 #endif
 891 #ifdef CONFIG_IP_ROUTE_MULTIPATH
 892                 nh->nh_weight = 1;
 893 #endif
 894         }
 895
 896         if (fib_props[cfg->fc_type].error) {
 897                 if (cfg->fc_gw || cfg->fc_oif || cfg->fc_mp)
 898                         goto err_inval;
 899                 goto link_it;
 900         } else {
 901                 switch (cfg->fc_type) {
 902                 case RTN_UNICAST:
 903                 case RTN_LOCAL:
 904                 case RTN_BROADCAST:
 905                 case RTN_ANYCAST:
 906                 case RTN_MULTICAST:
 907                         break;
 908                 default:
 909                         goto err_inval;
 910                 }
 911         }
 912
 913         if (cfg->fc_scope > RT_SCOPE_HOST)
 914                 goto err_inval;
 915
 916         if (cfg->fc_scope == RT_SCOPE_HOST) {
 917                 struct fib_nh *nh = fi->fib_nh;
 918
 919                 /* Local address is added. */
 920                 if (nhs != 1 || nh->nh_gw)
 921                         goto err_inval;
 922                 nh->nh_scope = RT_SCOPE_NOWHERE;
 923                 nh->nh_dev = dev_get_by_index(net, fi->fib_nh->nh_oif);
 924                 err = -ENODEV;
 925                 if (nh->nh_dev == NULL)
 926                         goto failure;
 927         } else {
 928                 change_nexthops(fi) {
 929                         err = fib_check_nh(cfg, fi, nexthop_nh);
 930                         if (err != 0)
 931                                 goto failure;
 932                 } endfor_nexthops(fi)
 933         }
 934
 935         if (fi->fib_prefsrc) {
 936                 if (cfg->fc_type != RTN_LOCAL || !cfg->fc_dst ||
 937                     fi->fib_prefsrc != cfg->fc_dst)
 938                         if (inet_addr_type(net, fi->fib_prefsrc) != RTN_LOCAL)
 939                                 goto err_inval;
 940         }
 941
 942         change_nexthops(fi) {
 943                 fib_info_update_nh_saddr(net, nexthop_nh);
 944         } endfor_nexthops(fi)
 945
 946 link_it:
 947         ofi = fib_find_info(fi);
 948         if (ofi) {
 949                 fi->fib_dead = 1;
 950                 free_fib_info(fi);
 951                 ofi->fib_treeref++;
 952                 return ofi;
 953         }
 954
 955         fi->fib_treeref++;
 956         atomic_inc(&fi->fib_clntref);
 957         spin_lock_bh(&fib_info_lock);
 958         hlist_add_head(&fi->fib_hash,
 959                        &fib_info_hash[fib_info_hashfn(fi)]);
 960         if (fi->fib_prefsrc) {
 961                 struct hlist_head *head;
 962
 963                 head = &fib_info_laddrhash[fib_laddr_hashfn(fi->fib_prefsrc)];
 964                 hlist_add_head(&fi->fib_lhash, head);
 965         }
 966         change_nexthops(fi) {
 967                 struct hlist_head *head;
 968                 unsigned int hash;
 969
 970                 if (!nexthop_nh->nh_dev)
 971                         continue;
 972                 hash = fib_devindex_hashfn(nexthop_nh->nh_dev->ifindex);
 973                 head = &fib_info_devhash[hash];
 974                 hlist_add_head(&nexthop_nh->nh_hash, head);
 975         } endfor_nexthops(fi)
 976         spin_unlock_bh(&fib_info_lock);
 977         return fi;
 978
 979 err_inval:
 980         err = -EINVAL;
 981
 982 failure:
 983         if (fi) {
 984                 fi->fib_dead = 1;
 985                 free_fib_info(fi);
 986         }
 987
 988         return ERR_PTR(err);
 989 }
 990
 991 int fib_dump_info(struct sk_buff *skb, u32 portid, u32 seq, int event,
 992                   u32 tb_id, u8 type, __be32 dst, int dst_len, u8 tos,
 993                   struct fib_info *fi, unsigned int flags)
 994 {
 995         struct nlmsghdr *nlh;
 996         struct rtmsg *rtm;
 997
 998         nlh = nlmsg_put(skb, portid, seq, event, sizeof(*rtm), flags);
 999         if (nlh == NULL)
1000                 return -EMSGSIZE;
1001
1002         rtm = nlmsg_data(nlh);
1003         rtm->rtm_family = AF_INET;
1004         rtm->rtm_dst_len = dst_len;
1005         rtm->rtm_src_len = 0;
1006         rtm->rtm_tos = tos;
1007         if (tb_id < 256)
1008                 rtm->rtm_table = tb_id;
1009         else
1010                 rtm->rtm_table = RT_TABLE_COMPAT;
1011         if (nla_put_u32(skb, RTA_TABLE, tb_id))
1012                 goto nla_put_failure;
1013         rtm->rtm_type = type;
1014         rtm->rtm_flags = fi->fib_flags;
1015         rtm->rtm_scope = fi->fib_scope;
1016         rtm->rtm_protocol = fi->fib_protocol;
1017
1018         if (rtm->rtm_dst_len &&
1019             nla_put_be32(skb, RTA_DST, dst))
1020                 goto nla_put_failure;
1021         if (fi->fib_priority &&
1022             nla_put_u32(skb, RTA_PRIORITY, fi->fib_priority))
1023                 goto nla_put_failure;
1024         if (rtnetlink_put_metrics(skb, fi->fib_metrics) < 0)
1025                 goto nla_put_failure;
1026
1027         if (fi->fib_prefsrc &&
1028             nla_put_be32(skb, RTA_PREFSRC, fi->fib_prefsrc))
1029                 goto nla_put_failure;
1030         if (fi->fib_nhs == 1) {
1031                 if (fi->fib_nh->nh_gw &&
1032                     nla_put_be32(skb, RTA_GATEWAY, fi->fib_nh->nh_gw))
1033                         goto nla_put_failure;
1034                 if (fi->fib_nh->nh_oif &&
1035                     nla_put_u32(skb, RTA_OIF, fi->fib_nh->nh_oif))
1036                         goto nla_put_failure;
1037 #ifdef CONFIG_IP_ROUTE_CLASSID
1038                 if (fi->fib_nh[0].nh_tclassid &&
1039                     nla_put_u32(skb, RTA_FLOW, fi->fib_nh[0].nh_tclassid))
1040                         goto nla_put_failure;
1041 #endif
1042         }
1043 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1044         if (fi->fib_nhs > 1) {
1045                 struct rtnexthop *rtnh;
1046                 struct nlattr *mp;
1047
1048                 mp = nla_nest_start(skb, RTA_MULTIPATH);
1049                 if (mp == NULL)
1050                         goto nla_put_failure;
1051
1052                 for_nexthops(fi) {
1053                         rtnh = nla_reserve_nohdr(skb, sizeof(*rtnh));
1054                         if (rtnh == NULL)
1055                                 goto nla_put_failure;
1056
1057                         rtnh->rtnh_flags = nh->nh_flags & 0xFF;
1058                         rtnh->rtnh_hops = nh->nh_weight - 1;
1059                         rtnh->rtnh_ifindex = nh->nh_oif;
1060
1061                         if (nh->nh_gw &&
1062                             nla_put_be32(skb, RTA_GATEWAY, nh->nh_gw))
1063                                 goto nla_put_failure;
1064 #ifdef CONFIG_IP_ROUTE_CLASSID
1065                         if (nh->nh_tclassid &&
1066                             nla_put_u32(skb, RTA_FLOW, nh->nh_tclassid))
1067                                 goto nla_put_failure;
1068 #endif
1069                         /* length of rtnetlink header + attributes */
1070                         rtnh->rtnh_len = nlmsg_get_pos(skb) - (void *) rtnh;
1071                 } endfor_nexthops(fi);
1072
1073                 nla_nest_end(skb, mp);
1074         }
1075 #endif
1076         nlmsg_end(skb, nlh);
1077         return 0;
1078
1079 nla_put_failure:
1080         nlmsg_cancel(skb, nlh);
1081         return -EMSGSIZE;
1082 }
1083
1084 /*
1085  * Update FIB if:
1086  * - local address disappeared -> we must delete all the entries
1087  *   referring to it.
1088  * - device went down -> we must shutdown all nexthops going via it.
1089  */
1090 int fib_sync_down_addr(struct net *net, __be32 local)
1091 {
1092         int ret = 0;
1093         unsigned int hash = fib_laddr_hashfn(local);
1094         struct hlist_head *head = &fib_info_laddrhash[hash];
1095         struct fib_info *fi;
1096
1097         if (fib_info_laddrhash == NULL || local == 0)
1098                 return 0;
1099
1100         hlist_for_each_entry(fi, head, fib_lhash) {
1101                 if (!net_eq(fi->fib_net, net))
1102                         continue;
1103                 if (fi->fib_prefsrc == local) {
1104                         fi->fib_flags |= RTNH_F_DEAD;
1105                         ret++;
1106                 }
1107         }
1108         return ret;
1109 }
1110
1111 int fib_sync_down_dev(struct net_device *dev, int force)
1112 {
1113         int ret = 0;
1114         int scope = RT_SCOPE_NOWHERE;
1115         struct fib_info *prev_fi = NULL;
1116         unsigned int hash = fib_devindex_hashfn(dev->ifindex);
1117         struct hlist_head *head = &fib_info_devhash[hash];
1118         struct fib_nh *nh;
1119
1120         if (force)
1121                 scope = -1;
1122
1123         hlist_for_each_entry(nh, head, nh_hash) {
1124                 struct fib_info *fi = nh->nh_parent;
1125                 int dead;
1126
1127                 BUG_ON(!fi->fib_nhs);
1128                 if (nh->nh_dev != dev || fi == prev_fi)
1129                         continue;
1130                 prev_fi = fi;
1131                 dead = 0;
1132                 change_nexthops(fi) {
1133                         if (nexthop_nh->nh_flags & RTNH_F_DEAD)
1134                                 dead++;
1135                         else if (nexthop_nh->nh_dev == dev &&
1136                                  nexthop_nh->nh_scope != scope) {
1137                                 nexthop_nh->nh_flags |= RTNH_F_DEAD;
1138 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1139                                 spin_lock_bh(&fib_multipath_lock);
1140                                 fi->fib_power -= nexthop_nh->nh_power;
1141                                 nexthop_nh->nh_power = 0;
1142                                 spin_unlock_bh(&fib_multipath_lock);
1143 #endif
1144                                 dead++;
1145                         }
1146 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1147                         if (force > 1 && nexthop_nh->nh_dev == dev) {
1148                                 dead = fi->fib_nhs;
1149                                 break;
1150                         }
1151 #endif
1152                 } endfor_nexthops(fi)
1153                 if (dead == fi->fib_nhs) {
1154                         fi->fib_flags |= RTNH_F_DEAD;
1155                         ret++;
1156                 }
1157         }
1158
1159         return ret;
1160 }
1161
1162 /* Must be invoked inside of an RCU protected region.  */
1163 void fib_select_default(struct fib_result *res)
1164 {
1165         struct fib_info *fi = NULL, *last_resort = NULL;
1166         struct hlist_head *fa_head = res->fa_head;
1167         struct fib_table *tb = res->table;
1168         int order = -1, last_idx = -1;
1169         struct fib_alias *fa;
1170
1171         hlist_for_each_entry_rcu(fa, fa_head, fa_list) {
1172                 struct fib_info *next_fi = fa->fa_info;
1173
1174                 if (next_fi->fib_scope != res->scope ||
1175                     fa->fa_type != RTN_UNICAST)
1176                         continue;
1177
1178                 if (next_fi->fib_priority > res->fi->fib_priority)
1179                         break;
1180                 if (!next_fi->fib_nh[0].nh_gw ||
1181                     next_fi->fib_nh[0].nh_scope != RT_SCOPE_LINK)
1182                         continue;
1183
1184                 fib_alias_accessed(fa);
1185
1186                 if (fi == NULL) {
1187                         if (next_fi != res->fi)
1188                                 break;
1189                 } else if (!fib_detect_death(fi, order, &last_resort,
1190                                              &last_idx, tb->tb_default)) {
1191                         fib_result_assign(res, fi);
1192                         tb->tb_default = order;
1193                         goto out;
1194                 }
1195                 fi = next_fi;
1196                 order++;
1197         }
1198
1199         if (order <= 0 || fi == NULL) {
1200                 tb->tb_default = -1;
1201                 goto out;
1202         }
1203
1204         if (!fib_detect_death(fi, order, &last_resort, &last_idx,
1205                                 tb->tb_default)) {
1206                 fib_result_assign(res, fi);
1207                 tb->tb_default = order;
1208                 goto out;
1209         }
1210
1211         if (last_idx >= 0)
1212                 fib_result_assign(res, last_resort);
1213         tb->tb_default = last_idx;
1214 out:
1215         return;
1216 }
1217
1218 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1219
1220 /*
1221  * Dead device goes up. We wake up dead nexthops.
1222  * It takes sense only on multipath routes.
1223  */
1224 int fib_sync_up(struct net_device *dev)
1225 {
1226         struct fib_info *prev_fi;
1227         unsigned int hash;
1228         struct hlist_head *head;
1229         struct fib_nh *nh;
1230         int ret;
1231
1232         if (!(dev->flags & IFF_UP))
1233                 return 0;
1234
1235         prev_fi = NULL;
1236         hash = fib_devindex_hashfn(dev->ifindex);
1237         head = &fib_info_devhash[hash];
1238         ret = 0;
1239
1240         hlist_for_each_entry(nh, head, nh_hash) {
1241                 struct fib_info *fi = nh->nh_parent;
1242                 int alive;
1243
1244                 BUG_ON(!fi->fib_nhs);
1245                 if (nh->nh_dev != dev || fi == prev_fi)
1246                         continue;
1247
1248                 prev_fi = fi;
1249                 alive = 0;
1250                 change_nexthops(fi) {
1251                         if (!(nexthop_nh->nh_flags & RTNH_F_DEAD)) {
1252                                 alive++;
1253                                 continue;
1254                         }
1255                         if (nexthop_nh->nh_dev == NULL ||
1256                             !(nexthop_nh->nh_dev->flags & IFF_UP))
1257                                 continue;
1258                         if (nexthop_nh->nh_dev != dev ||
1259                             !__in_dev_get_rtnl(dev))
1260                                 continue;
1261                         alive++;
1262                         spin_lock_bh(&fib_multipath_lock);
1263                         nexthop_nh->nh_power = 0;
1264                         nexthop_nh->nh_flags &= ~RTNH_F_DEAD;
1265                         spin_unlock_bh(&fib_multipath_lock);
1266                 } endfor_nexthops(fi)
1267
1268                 if (alive > 0) {
1269                         fi->fib_flags &= ~RTNH_F_DEAD;
1270                         ret++;
1271                 }
1272         }
1273
1274         return ret;
1275 }
1276
1277 /*
1278  * The algorithm is suboptimal, but it provides really
1279  * fair weighted route distribution.
1280  */
1281 void fib_select_multipath(struct fib_result *res)
1282 {
1283         struct fib_info *fi = res->fi;
1284         int w;
1285
1286         spin_lock_bh(&fib_multipath_lock);
1287         if (fi->fib_power <= 0) {
1288                 int power = 0;
1289                 change_nexthops(fi) {
1290                         if (!(nexthop_nh->nh_flags & RTNH_F_DEAD)) {
1291                                 power += nexthop_nh->nh_weight;
1292                                 nexthop_nh->nh_power = nexthop_nh->nh_weight;
1293                         }
1294                 } endfor_nexthops(fi);
1295                 fi->fib_power = power;
1296                 if (power <= 0) {
1297                         spin_unlock_bh(&fib_multipath_lock);
1298                         /* Race condition: route has just become dead. */
1299                         res->nh_sel = 0;
1300                         return;
1301                 }
1302         }
1303
1304
1305         /* w should be random number [0..fi->fib_power-1],
1306          * it is pretty bad approximation.
1307          */
1308
1309         w = jiffies % fi->fib_power;
1310
1311         change_nexthops(fi) {
1312                 if (!(nexthop_nh->nh_flags & RTNH_F_DEAD) &&
1313                     nexthop_nh->nh_power) {
1314                         w -= nexthop_nh->nh_power;
1315                         if (w <= 0) {
1316                                 nexthop_nh->nh_power--;
1317                                 fi->fib_power--;
1318                                 res->nh_sel = nhsel;
1319                                 spin_unlock_bh(&fib_multipath_lock);
1320                                 return;
1321                         }
1322                 }
1323         } endfor_nexthops(fi);
1324
1325         /* Race condition: route has just become dead. */
1326         res->nh_sel = 0;
1327         spin_unlock_bh(&fib_multipath_lock);
1328 }
1329 #endif