net/ipv4/fib_semantics.c

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