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