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         struct dst_metrics *m;
 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         m = fi->fib_metrics;
 218         if (m != &dst_default_metrics && atomic_dec_and_test(&m->refcnt))
 219                 kfree(m);
 220         kfree(fi);
 221 }
 222
 223 void free_fib_info(struct fib_info *fi)
 224 {
 225         if (fi->fib_dead == 0) {
 226                 pr_warn("Freeing alive fib_info %p\n", fi);
 227                 return;
 228         }
 229         fib_info_cnt--;
 230 #ifdef CONFIG_IP_ROUTE_CLASSID
 231         change_nexthops(fi) {
 232                 if (nexthop_nh->nh_tclassid)
 233                         fi->fib_net->ipv4.fib_num_tclassid_users--;
 234         } endfor_nexthops(fi);
 235 #endif
 236         call_rcu(&fi->rcu, free_fib_info_rcu);
 237 }
 238 EXPORT_SYMBOL_GPL(free_fib_info);
 239
 240 void fib_release_info(struct fib_info *fi)
 241 {
 242         spin_lock_bh(&fib_info_lock);
 243         if (fi && --fi->fib_treeref == 0) {
 244                 hlist_del(&fi->fib_hash);
 245                 if (fi->fib_prefsrc)
 246                         hlist_del(&fi->fib_lhash);
 247                 change_nexthops(fi) {
 248                         if (!nexthop_nh->nh_dev)
 249                                 continue;
 250                         hlist_del(&nexthop_nh->nh_hash);
 251                 } endfor_nexthops(fi)
 252                 fi->fib_dead = 1;
 253                 fib_info_put(fi);
 254         }
 255         spin_unlock_bh(&fib_info_lock);
 256 }
 257
 258 static inline int nh_comp(const struct fib_info *fi, const struct fib_info *ofi)
 259 {
 260         const struct fib_nh *onh = ofi->fib_nh;
 261
 262         for_nexthops(fi) {
 263                 if (nh->nh_oif != onh->nh_oif ||
 264                     nh->nh_gw  != onh->nh_gw ||
 265                     nh->nh_scope != onh->nh_scope ||
 266 #ifdef CONFIG_IP_ROUTE_MULTIPATH
 267                     nh->nh_weight != onh->nh_weight ||
 268 #endif
 269 #ifdef CONFIG_IP_ROUTE_CLASSID
 270                     nh->nh_tclassid != onh->nh_tclassid ||
 271 #endif
 272                     lwtunnel_cmp_encap(nh->nh_lwtstate, onh->nh_lwtstate) ||
 273                     ((nh->nh_flags ^ onh->nh_flags) & ~RTNH_COMPARE_MASK))
 274                         return -1;
 275                 onh++;
 276         } endfor_nexthops(fi);
 277         return 0;
 278 }
 279
 280 static inline unsigned int fib_devindex_hashfn(unsigned int val)
 281 {
 282         unsigned int mask = DEVINDEX_HASHSIZE - 1;
 283
 284         return (val ^
 285                 (val >> DEVINDEX_HASHBITS) ^
 286                 (val >> (DEVINDEX_HASHBITS * 2))) & mask;
 287 }
 288
 289 static inline unsigned int fib_info_hashfn(const struct fib_info *fi)
 290 {
 291         unsigned int mask = (fib_info_hash_size - 1);
 292         unsigned int val = fi->fib_nhs;
 293
 294         val ^= (fi->fib_protocol << 8) | fi->fib_scope;
 295         val ^= (__force u32)fi->fib_prefsrc;
 296         val ^= fi->fib_priority;
 297         for_nexthops(fi) {
 298                 val ^= fib_devindex_hashfn(nh->nh_oif);
 299         } endfor_nexthops(fi)
 300
 301         return (val ^ (val >> 7) ^ (val >> 12)) & mask;
 302 }
 303
 304 static struct fib_info *fib_find_info(const struct fib_info *nfi)
 305 {
 306         struct hlist_head *head;
 307         struct fib_info *fi;
 308         unsigned int hash;
 309
 310         hash = fib_info_hashfn(nfi);
 311         head = &fib_info_hash[hash];
 312
 313         hlist_for_each_entry(fi, head, fib_hash) {
 314                 if (!net_eq(fi->fib_net, nfi->fib_net))
 315                         continue;
 316                 if (fi->fib_nhs != nfi->fib_nhs)
 317                         continue;
 318                 if (nfi->fib_protocol == fi->fib_protocol &&
 319                     nfi->fib_scope == fi->fib_scope &&
 320                     nfi->fib_prefsrc == fi->fib_prefsrc &&
 321                     nfi->fib_priority == fi->fib_priority &&
 322                     nfi->fib_type == fi->fib_type &&
 323                     memcmp(nfi->fib_metrics, fi->fib_metrics,
 324                            sizeof(u32) * RTAX_MAX) == 0 &&
 325                     !((nfi->fib_flags ^ fi->fib_flags) & ~RTNH_COMPARE_MASK) &&
 326                     (nfi->fib_nhs == 0 || nh_comp(fi, nfi) == 0))
 327                         return fi;
 328         }
 329
 330         return NULL;
 331 }
 332
 333 /* Check, that the gateway is already configured.
 334  * Used only by redirect accept routine.
 335  */
 336 int ip_fib_check_default(__be32 gw, struct net_device *dev)
 337 {
 338         struct hlist_head *head;
 339         struct fib_nh *nh;
 340         unsigned int hash;
 341
 342         spin_lock(&fib_info_lock);
 343
 344         hash = fib_devindex_hashfn(dev->ifindex);
 345         head = &fib_info_devhash[hash];
 346         hlist_for_each_entry(nh, head, nh_hash) {
 347                 if (nh->nh_dev == dev &&
 348                     nh->nh_gw == gw &&
 349                     !(nh->nh_flags & RTNH_F_DEAD)) {
 350                         spin_unlock(&fib_info_lock);
 351                         return 0;
 352                 }
 353         }
 354
 355         spin_unlock(&fib_info_lock);
 356
 357         return -1;
 358 }
 359
 360 static inline size_t fib_nlmsg_size(struct fib_info *fi)
 361 {
 362         size_t payload = NLMSG_ALIGN(sizeof(struct rtmsg))
 363                          + nla_total_size(4) /* RTA_TABLE */
 364                          + nla_total_size(4) /* RTA_DST */
 365                          + nla_total_size(4) /* RTA_PRIORITY */
 366                          + nla_total_size(4) /* RTA_PREFSRC */
 367                          + nla_total_size(TCP_CA_NAME_MAX); /* RTAX_CC_ALGO */
 368
 369         /* space for nested metrics */
 370         payload += nla_total_size((RTAX_MAX * nla_total_size(4)));
 371
 372         if (fi->fib_nhs) {
 373                 size_t nh_encapsize = 0;
 374                 /* Also handles the special case fib_nhs == 1 */
 375
 376                 /* each nexthop is packed in an attribute */
 377                 size_t nhsize = nla_total_size(sizeof(struct rtnexthop));
 378
 379                 /* may contain flow and gateway attribute */
 380                 nhsize += 2 * nla_total_size(4);
 381
 382                 /* grab encap info */
 383                 for_nexthops(fi) {
 384                         if (nh->nh_lwtstate) {
 385                                 /* RTA_ENCAP_TYPE */
 386                                 nh_encapsize += lwtunnel_get_encap_size(
 387                                                 nh->nh_lwtstate);
 388                                 /* RTA_ENCAP */
 389                                 nh_encapsize +=  nla_total_size(2);
 390                         }
 391                 } endfor_nexthops(fi);
 392
 393                 /* all nexthops are packed in a nested attribute */
 394                 payload += nla_total_size((fi->fib_nhs * nhsize) +
 395                                           nh_encapsize);
 396
 397         }
 398
 399         return payload;
 400 }
 401
 402 void rtmsg_fib(int event, __be32 key, struct fib_alias *fa,
 403                int dst_len, u32 tb_id, const struct nl_info *info,
 404                unsigned int nlm_flags)
 405 {
 406         struct sk_buff *skb;
 407         u32 seq = info->nlh ? info->nlh->nlmsg_seq : 0;
 408         int err = -ENOBUFS;
 409
 410         skb = nlmsg_new(fib_nlmsg_size(fa->fa_info), GFP_KERNEL);
 411         if (!skb)
 412                 goto errout;
 413
 414         err = fib_dump_info(skb, info->portid, seq, event, tb_id,
 415                             fa->fa_type, key, dst_len,
 416                             fa->fa_tos, fa->fa_info, nlm_flags);
 417         if (err < 0) {
 418                 /* -EMSGSIZE implies BUG in fib_nlmsg_size() */
 419                 WARN_ON(err == -EMSGSIZE);
 420                 kfree_skb(skb);
 421                 goto errout;
 422         }
 423         rtnl_notify(skb, info->nl_net, info->portid, RTNLGRP_IPV4_ROUTE,
 424                     info->nlh, GFP_KERNEL);
 425         return;
 426 errout:
 427         if (err < 0)
 428                 rtnl_set_sk_err(info->nl_net, RTNLGRP_IPV4_ROUTE, err);
 429 }
 430
 431 static int fib_detect_death(struct fib_info *fi, int order,
 432                             struct fib_info **last_resort, int *last_idx,
 433                             int dflt)
 434 {
 435         struct neighbour *n;
 436         int state = NUD_NONE;
 437
 438         n = neigh_lookup(&arp_tbl, &fi->fib_nh[0].nh_gw, fi->fib_dev);
 439         if (n) {
 440                 state = n->nud_state;
 441                 neigh_release(n);
 442         } else {
 443                 return 0;
 444         }
 445         if (state == NUD_REACHABLE)
 446                 return 0;
 447         if ((state & NUD_VALID) && order != dflt)
 448                 return 0;
 449         if ((state & NUD_VALID) ||
 450             (*last_idx < 0 && order > dflt && state != NUD_INCOMPLETE)) {
 451                 *last_resort = fi;
 452                 *last_idx = order;
 453         }
 454         return 1;
 455 }
 456
 457 #ifdef CONFIG_IP_ROUTE_MULTIPATH
 458
 459 static int fib_count_nexthops(struct rtnexthop *rtnh, int remaining)
 460 {
 461         int nhs = 0;
 462
 463         while (rtnh_ok(rtnh, remaining)) {
 464                 nhs++;
 465                 rtnh = rtnh_next(rtnh, &remaining);
 466         }
 467
 468         /* leftover implies invalid nexthop configuration, discard it */
 469         return remaining > 0 ? 0 : nhs;
 470 }
 471
 472 static int fib_get_nhs(struct fib_info *fi, struct rtnexthop *rtnh,
 473                        int remaining, struct fib_config *cfg)
 474 {
 475         int ret;
 476
 477         change_nexthops(fi) {
 478                 int attrlen;
 479
 480                 if (!rtnh_ok(rtnh, remaining))
 481                         return -EINVAL;
 482
 483                 if (rtnh->rtnh_flags & (RTNH_F_DEAD | RTNH_F_LINKDOWN))
 484                         return -EINVAL;
 485
 486                 nexthop_nh->nh_flags =
 487                         (cfg->fc_flags & ~0xFF) | rtnh->rtnh_flags;
 488                 nexthop_nh->nh_oif = rtnh->rtnh_ifindex;
 489                 nexthop_nh->nh_weight = rtnh->rtnh_hops + 1;
 490
 491                 attrlen = rtnh_attrlen(rtnh);
 492                 if (attrlen > 0) {
 493                         struct nlattr *nla, *attrs = rtnh_attrs(rtnh);
 494
 495                         nla = nla_find(attrs, attrlen, RTA_GATEWAY);
 496                         nexthop_nh->nh_gw = nla ? nla_get_in_addr(nla) : 0;
 497 #ifdef CONFIG_IP_ROUTE_CLASSID
 498                         nla = nla_find(attrs, attrlen, RTA_FLOW);
 499                         nexthop_nh->nh_tclassid = nla ? nla_get_u32(nla) : 0;
 500                         if (nexthop_nh->nh_tclassid)
 501                                 fi->fib_net->ipv4.fib_num_tclassid_users++;
 502 #endif
 503                         nla = nla_find(attrs, attrlen, RTA_ENCAP);
 504                         if (nla) {
 505                                 struct lwtunnel_state *lwtstate;
 506                                 struct nlattr *nla_entype;
 507
 508                                 nla_entype = nla_find(attrs, attrlen,
 509                                                       RTA_ENCAP_TYPE);
 510                                 if (!nla_entype)
 511                                         goto err_inval;
 512
 513                                 ret = lwtunnel_build_state(nla_get_u16(
 514                                                            nla_entype),
 515                                                            nla,  AF_INET, cfg,
 516                                                            &lwtstate);
 517                                 if (ret)
 518                                         goto errout;
 519                                 nexthop_nh->nh_lwtstate =
 520                                         lwtstate_get(lwtstate);
 521                         }
 522                 }
 523
 524                 rtnh = rtnh_next(rtnh, &remaining);
 525         } endfor_nexthops(fi);
 526
 527         return 0;
 528
 529 err_inval:
 530         ret = -EINVAL;
 531
 532 errout:
 533         return ret;
 534 }
 535
 536 static void fib_rebalance(struct fib_info *fi)
 537 {
 538         int total;
 539         int w;
 540         struct in_device *in_dev;
 541
 542         if (fi->fib_nhs < 2)
 543                 return;
 544
 545         total = 0;
 546         for_nexthops(fi) {
 547                 if (nh->nh_flags & RTNH_F_DEAD)
 548                         continue;
 549
 550                 in_dev = __in_dev_get_rtnl(nh->nh_dev);
 551
 552                 if (in_dev &&
 553                     IN_DEV_IGNORE_ROUTES_WITH_LINKDOWN(in_dev) &&
 554                     nh->nh_flags & RTNH_F_LINKDOWN)
 555                         continue;
 556
 557                 total += nh->nh_weight;
 558         } endfor_nexthops(fi);
 559
 560         w = 0;
 561         change_nexthops(fi) {
 562                 int upper_bound;
 563
 564                 in_dev = __in_dev_get_rtnl(nexthop_nh->nh_dev);
 565
 566                 if (nexthop_nh->nh_flags & RTNH_F_DEAD) {
 567                         upper_bound = -1;
 568                 } else if (in_dev &&
 569                            IN_DEV_IGNORE_ROUTES_WITH_LINKDOWN(in_dev) &&
 570                            nexthop_nh->nh_flags & RTNH_F_LINKDOWN) {
 571                         upper_bound = -1;
 572                 } else {
 573                         w += nexthop_nh->nh_weight;
 574                         upper_bound = DIV_ROUND_CLOSEST_ULL((u64)w << 31,
 575                                                             total) - 1;
 576                 }
 577
 578                 atomic_set(&nexthop_nh->nh_upper_bound, upper_bound);
 579         } endfor_nexthops(fi);
 580 }
 581
 582 static inline void fib_add_weight(struct fib_info *fi,
 583                                   const struct fib_nh *nh)
 584 {
 585         fi->fib_weight += nh->nh_weight;
 586 }
 587
 588 #else /* CONFIG_IP_ROUTE_MULTIPATH */
 589
 590 #define fib_rebalance(fi) do { } while (0)
 591 #define fib_add_weight(fi, nh) do { } while (0)
 592
 593 #endif /* CONFIG_IP_ROUTE_MULTIPATH */
 594
 595 static int fib_encap_match(u16 encap_type,
 596                            struct nlattr *encap,
 597                            const struct fib_nh *nh,
 598                            const struct fib_config *cfg)
 599 {
 600         struct lwtunnel_state *lwtstate;
 601         int ret, result = 0;
 602
 603         if (encap_type == LWTUNNEL_ENCAP_NONE)
 604                 return 0;
 605
 606         ret = lwtunnel_build_state(encap_type, encap,
 607                                    AF_INET, cfg, &lwtstate);
 608         if (!ret) {
 609                 result = lwtunnel_cmp_encap(lwtstate, nh->nh_lwtstate);
 610                 lwtstate_free(lwtstate);
 611         }
 612
 613         return result;
 614 }
 615
 616 int fib_nh_match(struct fib_config *cfg, struct fib_info *fi)
 617 {
 618 #ifdef CONFIG_IP_ROUTE_MULTIPATH
 619         struct rtnexthop *rtnh;
 620         int remaining;
 621 #endif
 622
 623         if (cfg->fc_priority && cfg->fc_priority != fi->fib_priority)
 624                 return 1;
 625
 626         if (cfg->fc_oif || cfg->fc_gw) {
 627                 if (cfg->fc_encap) {
 628                         if (fib_encap_match(cfg->fc_encap_type,
 629                                             cfg->fc_encap, fi->fib_nh, cfg))
 630                             return 1;
 631                 }
 632                 if ((!cfg->fc_oif || cfg->fc_oif == fi->fib_nh->nh_oif) &&
 633                     (!cfg->fc_gw  || cfg->fc_gw == fi->fib_nh->nh_gw))
 634                         return 0;
 635                 return 1;
 636         }
 637
 638 #ifdef CONFIG_IP_ROUTE_MULTIPATH
 639         if (!cfg->fc_mp)
 640                 return 0;
 641
 642         rtnh = cfg->fc_mp;
 643         remaining = cfg->fc_mp_len;
 644
 645         for_nexthops(fi) {
 646                 int attrlen;
 647
 648                 if (!rtnh_ok(rtnh, remaining))
 649                         return -EINVAL;
 650
 651                 if (rtnh->rtnh_ifindex && rtnh->rtnh_ifindex != nh->nh_oif)
 652                         return 1;
 653
 654                 attrlen = rtnh_attrlen(rtnh);
 655                 if (attrlen > 0) {
 656                         struct nlattr *nla, *attrs = rtnh_attrs(rtnh);
 657
 658                         nla = nla_find(attrs, attrlen, RTA_GATEWAY);
 659                         if (nla && nla_get_in_addr(nla) != nh->nh_gw)
 660                                 return 1;
 661 #ifdef CONFIG_IP_ROUTE_CLASSID
 662                         nla = nla_find(attrs, attrlen, RTA_FLOW);
 663                         if (nla && nla_get_u32(nla) != nh->nh_tclassid)
 664                                 return 1;
 665 #endif
 666                 }
 667
 668                 rtnh = rtnh_next(rtnh, &remaining);
 669         } endfor_nexthops(fi);
 670 #endif
 671         return 0;
 672 }
 673
 674
 675 /*
 676  * Picture
 677  * -------
 678  *
 679  * Semantics of nexthop is very messy by historical reasons.
 680  * We have to take into account, that:
 681  * a) gateway can be actually local interface address,
 682  *    so that gatewayed route is direct.
 683  * b) gateway must be on-link address, possibly
 684  *    described not by an ifaddr, but also by a direct route.
 685  * c) If both gateway and interface are specified, they should not
 686  *    contradict.
 687  * d) If we use tunnel routes, gateway could be not on-link.
 688  *
 689  * Attempt to reconcile all of these (alas, self-contradictory) conditions
 690  * results in pretty ugly and hairy code with obscure logic.
 691  *
 692  * I chose to generalized it instead, so that the size
 693  * of code does not increase practically, but it becomes
 694  * much more general.
 695  * Every prefix is assigned a "scope" value: "host" is local address,
 696  * "link" is direct route,
 697  * [ ... "site" ... "interior" ... ]
 698  * and "universe" is true gateway route with global meaning.
 699  *
 700  * Every prefix refers to a set of "nexthop"s (gw, oif),
 701  * where gw must have narrower scope. This recursion stops
 702  * when gw has LOCAL scope or if "nexthop" is declared ONLINK,
 703  * which means that gw is forced to be on link.
 704  *
 705  * Code is still hairy, but now it is apparently logically
 706  * consistent and very flexible. F.e. as by-product it allows
 707  * to co-exists in peace independent exterior and interior
 708  * routing processes.
 709  *
 710  * Normally it looks as following.
 711  *
 712  * {universe prefix}  -> (gw, oif) [scope link]
 713  *                |
 714  *                |-> {link prefix} -> (gw, oif) [scope local]
 715  *                                      |
 716  *                                      |-> {local prefix} (terminal node)
 717  */
 718 static int fib_check_nh(struct fib_config *cfg, struct fib_info *fi,
 719                         struct fib_nh *nh)
 720 {
 721         int err = 0;
 722         struct net *net;
 723         struct net_device *dev;
 724
 725         net = cfg->fc_nlinfo.nl_net;
 726         if (nh->nh_gw) {
 727                 struct fib_result res;
 728
 729                 if (nh->nh_flags & RTNH_F_ONLINK) {
 730                         unsigned int addr_type;
 731
 732                         if (cfg->fc_scope >= RT_SCOPE_LINK)
 733                                 return -EINVAL;
 734                         dev = __dev_get_by_index(net, nh->nh_oif);
 735                         if (!dev)
 736                                 return -ENODEV;
 737                         if (!(dev->flags & IFF_UP))
 738                                 return -ENETDOWN;
 739                         addr_type = inet_addr_type_dev_table(net, dev, nh->nh_gw);
 740                         if (addr_type != RTN_UNICAST)
 741                                 return -EINVAL;
 742                         if (!netif_carrier_ok(dev))
 743                                 nh->nh_flags |= RTNH_F_LINKDOWN;
 744                         nh->nh_dev = dev;
 745                         dev_hold(dev);
 746                         nh->nh_scope = RT_SCOPE_LINK;
 747                         return 0;
 748                 }
 749                 rcu_read_lock();
 750                 {
 751                         struct fib_table *tbl = NULL;
 752                         struct flowi4 fl4 = {
 753                                 .daddr = nh->nh_gw,
 754                                 .flowi4_scope = cfg->fc_scope + 1,
 755                                 .flowi4_oif = nh->nh_oif,
 756                                 .flowi4_iif = LOOPBACK_IFINDEX,
 757                         };
 758
 759                         /* It is not necessary, but requires a bit of thinking */
 760                         if (fl4.flowi4_scope < RT_SCOPE_LINK)
 761                                 fl4.flowi4_scope = RT_SCOPE_LINK;
 762
 763                         if (cfg->fc_table)
 764                                 tbl = fib_get_table(net, cfg->fc_table);
 765
 766                         if (tbl)
 767                                 err = fib_table_lookup(tbl, &fl4, &res,
 768                                                        FIB_LOOKUP_IGNORE_LINKSTATE |
 769                                                        FIB_LOOKUP_NOREF);
 770
 771                         /* on error or if no table given do full lookup. This
 772                          * is needed for example when nexthops are in the local
 773                          * table rather than the given table
 774                          */
 775                         if (!tbl || err) {
 776                                 err = fib_lookup(net, &fl4, &res,
 777                                                  FIB_LOOKUP_IGNORE_LINKSTATE);
 778                         }
 779
 780                         if (err) {
 781                                 rcu_read_unlock();
 782                                 return err;
 783                         }
 784                 }
 785                 err = -EINVAL;
 786                 if (res.type != RTN_UNICAST && res.type != RTN_LOCAL)
 787                         goto out;
 788                 nh->nh_scope = res.scope;
 789                 nh->nh_oif = FIB_RES_OIF(res);
 790                 nh->nh_dev = dev = FIB_RES_DEV(res);
 791                 if (!dev)
 792                         goto out;
 793                 dev_hold(dev);
 794                 if (!netif_carrier_ok(dev))
 795                         nh->nh_flags |= RTNH_F_LINKDOWN;
 796                 err = (dev->flags & IFF_UP) ? 0 : -ENETDOWN;
 797         } else {
 798                 struct in_device *in_dev;
 799
 800                 if (nh->nh_flags & (RTNH_F_PERVASIVE | RTNH_F_ONLINK))
 801                         return -EINVAL;
 802
 803                 rcu_read_lock();
 804                 err = -ENODEV;
 805                 in_dev = inetdev_by_index(net, nh->nh_oif);
 806                 if (!in_dev)
 807                         goto out;
 808                 err = -ENETDOWN;
 809                 if (!(in_dev->dev->flags & IFF_UP))
 810                         goto out;
 811                 nh->nh_dev = in_dev->dev;
 812                 dev_hold(nh->nh_dev);
 813                 nh->nh_scope = RT_SCOPE_HOST;
 814                 if (!netif_carrier_ok(nh->nh_dev))
 815                         nh->nh_flags |= RTNH_F_LINKDOWN;
 816                 err = 0;
 817         }
 818 out:
 819         rcu_read_unlock();
 820         return err;
 821 }
 822
 823 static inline unsigned int fib_laddr_hashfn(__be32 val)
 824 {
 825         unsigned int mask = (fib_info_hash_size - 1);
 826
 827         return ((__force u32)val ^
 828                 ((__force u32)val >> 7) ^
 829                 ((__force u32)val >> 14)) & mask;
 830 }
 831
 832 static struct hlist_head *fib_info_hash_alloc(int bytes)
 833 {
 834         if (bytes <= PAGE_SIZE)
 835                 return kzalloc(bytes, GFP_KERNEL);
 836         else
 837                 return (struct hlist_head *)
 838                         __get_free_pages(GFP_KERNEL | __GFP_ZERO,
 839                                          get_order(bytes));
 840 }
 841
 842 static void fib_info_hash_free(struct hlist_head *hash, int bytes)
 843 {
 844         if (!hash)
 845                 return;
 846
 847         if (bytes <= PAGE_SIZE)
 848                 kfree(hash);
 849         else
 850                 free_pages((unsigned long) hash, get_order(bytes));
 851 }
 852
 853 static void fib_info_hash_move(struct hlist_head *new_info_hash,
 854                                struct hlist_head *new_laddrhash,
 855                                unsigned int new_size)
 856 {
 857         struct hlist_head *old_info_hash, *old_laddrhash;
 858         unsigned int old_size = fib_info_hash_size;
 859         unsigned int i, bytes;
 860
 861         spin_lock_bh(&fib_info_lock);
 862         old_info_hash = fib_info_hash;
 863         old_laddrhash = fib_info_laddrhash;
 864         fib_info_hash_size = new_size;
 865
 866         for (i = 0; i < old_size; i++) {
 867                 struct hlist_head *head = &fib_info_hash[i];
 868                 struct hlist_node *n;
 869                 struct fib_info *fi;
 870
 871                 hlist_for_each_entry_safe(fi, n, head, fib_hash) {
 872                         struct hlist_head *dest;
 873                         unsigned int new_hash;
 874
 875                         new_hash = fib_info_hashfn(fi);
 876                         dest = &new_info_hash[new_hash];
 877                         hlist_add_head(&fi->fib_hash, dest);
 878                 }
 879         }
 880         fib_info_hash = new_info_hash;
 881
 882         for (i = 0; i < old_size; i++) {
 883                 struct hlist_head *lhead = &fib_info_laddrhash[i];
 884                 struct hlist_node *n;
 885                 struct fib_info *fi;
 886
 887                 hlist_for_each_entry_safe(fi, n, lhead, fib_lhash) {
 888                         struct hlist_head *ldest;
 889                         unsigned int new_hash;
 890
 891                         new_hash = fib_laddr_hashfn(fi->fib_prefsrc);
 892                         ldest = &new_laddrhash[new_hash];
 893                         hlist_add_head(&fi->fib_lhash, ldest);
 894                 }
 895         }
 896         fib_info_laddrhash = new_laddrhash;
 897
 898         spin_unlock_bh(&fib_info_lock);
 899
 900         bytes = old_size * sizeof(struct hlist_head *);
 901         fib_info_hash_free(old_info_hash, bytes);
 902         fib_info_hash_free(old_laddrhash, bytes);
 903 }
 904
 905 __be32 fib_info_update_nh_saddr(struct net *net, struct fib_nh *nh)
 906 {
 907         nh->nh_saddr = inet_select_addr(nh->nh_dev,
 908                                         nh->nh_gw,
 909                                         nh->nh_parent->fib_scope);
 910         nh->nh_saddr_genid = atomic_read(&net->ipv4.dev_addr_genid);
 911
 912         return nh->nh_saddr;
 913 }
 914
 915 static bool fib_valid_prefsrc(struct fib_config *cfg, __be32 fib_prefsrc)
 916 {
 917         if (cfg->fc_type != RTN_LOCAL || !cfg->fc_dst ||
 918             fib_prefsrc != cfg->fc_dst) {
 919                 u32 tb_id = cfg->fc_table;
 920                 int rc;
 921
 922                 if (tb_id == RT_TABLE_MAIN)
 923                         tb_id = RT_TABLE_LOCAL;
 924
 925                 rc = inet_addr_type_table(cfg->fc_nlinfo.nl_net,
 926                                           fib_prefsrc, tb_id);
 927
 928                 if (rc != RTN_LOCAL && tb_id != RT_TABLE_LOCAL) {
 929                         rc = inet_addr_type_table(cfg->fc_nlinfo.nl_net,
 930                                                   fib_prefsrc, RT_TABLE_LOCAL);
 931                 }
 932
 933                 if (rc != RTN_LOCAL)
 934                         return false;
 935         }
 936         return true;
 937 }
 938
 939 static int
 940 fib_convert_metrics(struct fib_info *fi, const struct fib_config *cfg)
 941 {
 942         bool ecn_ca = false;
 943         struct nlattr *nla;
 944         int remaining;
 945
 946         if (!cfg->fc_mx)
 947                 return 0;
 948
 949         nla_for_each_attr(nla, cfg->fc_mx, cfg->fc_mx_len, remaining) {
 950                 int type = nla_type(nla);
 951                 u32 val;
 952
 953                 if (!type)
 954                         continue;
 955                 if (type > RTAX_MAX)
 956                         return -EINVAL;
 957
 958                 if (type == RTAX_CC_ALGO) {
 959                         char tmp[TCP_CA_NAME_MAX];
 960
 961                         nla_strlcpy(tmp, nla, sizeof(tmp));
 962                         val = tcp_ca_get_key_by_name(tmp, &ecn_ca);
 963                         if (val == TCP_CA_UNSPEC)
 964                                 return -EINVAL;
 965                 } else {
 966                         val = nla_get_u32(nla);
 967                 }
 968                 if (type == RTAX_ADVMSS && val > 65535 - 40)
 969                         val = 65535 - 40;
 970                 if (type == RTAX_MTU && val > 65535 - 15)
 971                         val = 65535 - 15;
 972                 if (type == RTAX_HOPLIMIT && val > 255)
 973                         val = 255;
 974                 if (type == RTAX_FEATURES && (val & ~RTAX_FEATURE_MASK))
 975                         return -EINVAL;
 976                 fi->fib_metrics->metrics[type - 1] = val;
 977         }
 978
 979         if (ecn_ca)
 980                 fi->fib_metrics->metrics[RTAX_FEATURES - 1] |= DST_FEATURE_ECN_CA;
 981
 982         return 0;
 983 }
 984
 985 struct fib_info *fib_create_info(struct fib_config *cfg)
 986 {
 987         int err;
 988         struct fib_info *fi = NULL;
 989         struct fib_info *ofi;
 990         int nhs = 1;
 991         struct net *net = cfg->fc_nlinfo.nl_net;
 992
 993         if (cfg->fc_type > RTN_MAX)
 994                 goto err_inval;
 995
 996         /* Fast check to catch the most weird cases */
 997         if (fib_props[cfg->fc_type].scope > cfg->fc_scope)
 998                 goto err_inval;
 999
1000         if (cfg->fc_flags & (RTNH_F_DEAD | RTNH_F_LINKDOWN))
1001                 goto err_inval;
1002
1003 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1004         if (cfg->fc_mp) {
1005                 nhs = fib_count_nexthops(cfg->fc_mp, cfg->fc_mp_len);
1006                 if (nhs == 0)
1007                         goto err_inval;
1008         }
1009 #endif
1010
1011         err = -ENOBUFS;
1012         if (fib_info_cnt >= fib_info_hash_size) {
1013                 unsigned int new_size = fib_info_hash_size << 1;
1014                 struct hlist_head *new_info_hash;
1015                 struct hlist_head *new_laddrhash;
1016                 unsigned int bytes;
1017
1018                 if (!new_size)
1019                         new_size = 16;
1020                 bytes = new_size * sizeof(struct hlist_head *);
1021                 new_info_hash = fib_info_hash_alloc(bytes);
1022                 new_laddrhash = fib_info_hash_alloc(bytes);
1023                 if (!new_info_hash || !new_laddrhash) {
1024                         fib_info_hash_free(new_info_hash, bytes);
1025                         fib_info_hash_free(new_laddrhash, bytes);
1026                 } else
1027                         fib_info_hash_move(new_info_hash, new_laddrhash, new_size);
1028
1029                 if (!fib_info_hash_size)
1030                         goto failure;
1031         }
1032
1033         fi = kzalloc(sizeof(*fi)+nhs*sizeof(struct fib_nh), GFP_KERNEL);
1034         if (!fi)
1035                 goto failure;
1036         fib_info_cnt++;
1037         if (cfg->fc_mx) {
1038                 fi->fib_metrics = kzalloc(sizeof(*fi->fib_metrics), GFP_KERNEL);
1039                 if (!fi->fib_metrics)
1040                         goto failure;
1041                 atomic_set(&fi->fib_metrics->refcnt, 1);
1042         } else
1043                 fi->fib_metrics = (struct dst_metrics *)&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         fi->fib_tb_id = cfg->fc_table;
1053
1054         fi->fib_nhs = nhs;
1055         change_nexthops(fi) {
1056                 nexthop_nh->nh_parent = fi;
1057                 nexthop_nh->nh_pcpu_rth_output = alloc_percpu(struct rtable __rcu *);
1058                 if (!nexthop_nh->nh_pcpu_rth_output)
1059                         goto failure;
1060         } endfor_nexthops(fi)
1061
1062         err = fib_convert_metrics(fi, cfg);
1063         if (err)
1064                 goto failure;
1065
1066         if (cfg->fc_mp) {
1067 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1068                 err = fib_get_nhs(fi, cfg->fc_mp, cfg->fc_mp_len, cfg);
1069                 if (err != 0)
1070                         goto failure;
1071                 if (cfg->fc_oif && fi->fib_nh->nh_oif != cfg->fc_oif)
1072                         goto err_inval;
1073                 if (cfg->fc_gw && fi->fib_nh->nh_gw != cfg->fc_gw)
1074                         goto err_inval;
1075 #ifdef CONFIG_IP_ROUTE_CLASSID
1076                 if (cfg->fc_flow && fi->fib_nh->nh_tclassid != cfg->fc_flow)
1077                         goto err_inval;
1078 #endif
1079 #else
1080                 goto err_inval;
1081 #endif
1082         } else {
1083                 struct fib_nh *nh = fi->fib_nh;
1084
1085                 if (cfg->fc_encap) {
1086                         struct lwtunnel_state *lwtstate;
1087
1088                         if (cfg->fc_encap_type == LWTUNNEL_ENCAP_NONE)
1089                                 goto err_inval;
1090                         err = lwtunnel_build_state(cfg->fc_encap_type,
1091                                                    cfg->fc_encap, AF_INET, cfg,
1092                                                    &lwtstate);
1093                         if (err)
1094                                 goto failure;
1095
1096                         nh->nh_lwtstate = lwtstate_get(lwtstate);
1097                 }
1098                 nh->nh_oif = cfg->fc_oif;
1099                 nh->nh_gw = cfg->fc_gw;
1100                 nh->nh_flags = cfg->fc_flags;
1101 #ifdef CONFIG_IP_ROUTE_CLASSID
1102                 nh->nh_tclassid = cfg->fc_flow;
1103                 if (nh->nh_tclassid)
1104                         fi->fib_net->ipv4.fib_num_tclassid_users++;
1105 #endif
1106 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1107                 nh->nh_weight = 1;
1108 #endif
1109         }
1110
1111         if (fib_props[cfg->fc_type].error) {
1112                 if (cfg->fc_gw || cfg->fc_oif || cfg->fc_mp)
1113                         goto err_inval;
1114                 goto link_it;
1115         } else {
1116                 switch (cfg->fc_type) {
1117                 case RTN_UNICAST:
1118                 case RTN_LOCAL:
1119                 case RTN_BROADCAST:
1120                 case RTN_ANYCAST:
1121                 case RTN_MULTICAST:
1122                         break;
1123                 default:
1124                         goto err_inval;
1125                 }
1126         }
1127
1128         if (cfg->fc_scope > RT_SCOPE_HOST)
1129                 goto err_inval;
1130
1131         if (cfg->fc_scope == RT_SCOPE_HOST) {
1132                 struct fib_nh *nh = fi->fib_nh;
1133
1134                 /* Local address is added. */
1135                 if (nhs != 1 || nh->nh_gw)
1136                         goto err_inval;
1137                 nh->nh_scope = RT_SCOPE_NOWHERE;
1138                 nh->nh_dev = dev_get_by_index(net, fi->fib_nh->nh_oif);
1139                 err = -ENODEV;
1140                 if (!nh->nh_dev)
1141                         goto failure;
1142         } else {
1143                 int linkdown = 0;
1144
1145                 change_nexthops(fi) {
1146                         err = fib_check_nh(cfg, fi, nexthop_nh);
1147                         if (err != 0)
1148                                 goto failure;
1149                         if (nexthop_nh->nh_flags & RTNH_F_LINKDOWN)
1150                                 linkdown++;
1151                 } endfor_nexthops(fi)
1152                 if (linkdown == fi->fib_nhs)
1153                         fi->fib_flags |= RTNH_F_LINKDOWN;
1154         }
1155
1156         if (fi->fib_prefsrc && !fib_valid_prefsrc(cfg, fi->fib_prefsrc))
1157                 goto err_inval;
1158
1159         change_nexthops(fi) {
1160                 fib_info_update_nh_saddr(net, nexthop_nh);
1161                 fib_add_weight(fi, nexthop_nh);
1162         } endfor_nexthops(fi)
1163
1164         fib_rebalance(fi);
1165
1166 link_it:
1167         ofi = fib_find_info(fi);
1168         if (ofi) {
1169                 fi->fib_dead = 1;
1170                 free_fib_info(fi);
1171                 ofi->fib_treeref++;
1172                 return ofi;
1173         }
1174
1175         fi->fib_treeref++;
1176         atomic_inc(&fi->fib_clntref);
1177         spin_lock_bh(&fib_info_lock);
1178         hlist_add_head(&fi->fib_hash,
1179                        &fib_info_hash[fib_info_hashfn(fi)]);
1180         if (fi->fib_prefsrc) {
1181                 struct hlist_head *head;
1182
1183                 head = &fib_info_laddrhash[fib_laddr_hashfn(fi->fib_prefsrc)];
1184                 hlist_add_head(&fi->fib_lhash, head);
1185         }
1186         change_nexthops(fi) {
1187                 struct hlist_head *head;
1188                 unsigned int hash;
1189
1190                 if (!nexthop_nh->nh_dev)
1191                         continue;
1192                 hash = fib_devindex_hashfn(nexthop_nh->nh_dev->ifindex);
1193                 head = &fib_info_devhash[hash];
1194                 hlist_add_head(&nexthop_nh->nh_hash, head);
1195         } endfor_nexthops(fi)
1196         spin_unlock_bh(&fib_info_lock);
1197         return fi;
1198
1199 err_inval:
1200         err = -EINVAL;
1201
1202 failure:
1203         if (fi) {
1204                 fi->fib_dead = 1;
1205                 free_fib_info(fi);
1206         }
1207
1208         return ERR_PTR(err);
1209 }
1210
1211 int fib_dump_info(struct sk_buff *skb, u32 portid, u32 seq, int event,
1212                   u32 tb_id, u8 type, __be32 dst, int dst_len, u8 tos,
1213                   struct fib_info *fi, unsigned int flags)
1214 {
1215         struct nlmsghdr *nlh;
1216         struct rtmsg *rtm;
1217
1218         nlh = nlmsg_put(skb, portid, seq, event, sizeof(*rtm), flags);
1219         if (!nlh)
1220                 return -EMSGSIZE;
1221
1222         rtm = nlmsg_data(nlh);
1223         rtm->rtm_family = AF_INET;
1224         rtm->rtm_dst_len = dst_len;
1225         rtm->rtm_src_len = 0;
1226         rtm->rtm_tos = tos;
1227         if (tb_id < 256)
1228                 rtm->rtm_table = tb_id;
1229         else
1230                 rtm->rtm_table = RT_TABLE_COMPAT;
1231         if (nla_put_u32(skb, RTA_TABLE, tb_id))
1232                 goto nla_put_failure;
1233         rtm->rtm_type = type;
1234         rtm->rtm_flags = fi->fib_flags;
1235         rtm->rtm_scope = fi->fib_scope;
1236         rtm->rtm_protocol = fi->fib_protocol;
1237
1238         if (rtm->rtm_dst_len &&
1239             nla_put_in_addr(skb, RTA_DST, dst))
1240                 goto nla_put_failure;
1241         if (fi->fib_priority &&
1242             nla_put_u32(skb, RTA_PRIORITY, fi->fib_priority))
1243                 goto nla_put_failure;
1244         if (rtnetlink_put_metrics(skb, fi->fib_metrics->metrics) < 0)
1245                 goto nla_put_failure;
1246
1247         if (fi->fib_prefsrc &&
1248             nla_put_in_addr(skb, RTA_PREFSRC, fi->fib_prefsrc))
1249                 goto nla_put_failure;
1250         if (fi->fib_nhs == 1) {
1251                 struct in_device *in_dev;
1252
1253                 if (fi->fib_nh->nh_gw &&
1254                     nla_put_in_addr(skb, RTA_GATEWAY, fi->fib_nh->nh_gw))
1255                         goto nla_put_failure;
1256                 if (fi->fib_nh->nh_oif &&
1257                     nla_put_u32(skb, RTA_OIF, fi->fib_nh->nh_oif))
1258                         goto nla_put_failure;
1259                 if (fi->fib_nh->nh_flags & RTNH_F_LINKDOWN) {
1260                         in_dev = __in_dev_get_rtnl(fi->fib_nh->nh_dev);
1261                         if (in_dev &&
1262                             IN_DEV_IGNORE_ROUTES_WITH_LINKDOWN(in_dev))
1263                                 rtm->rtm_flags |= RTNH_F_DEAD;
1264                 }
1265 #ifdef CONFIG_IP_ROUTE_CLASSID
1266                 if (fi->fib_nh[0].nh_tclassid &&
1267                     nla_put_u32(skb, RTA_FLOW, fi->fib_nh[0].nh_tclassid))
1268                         goto nla_put_failure;
1269 #endif
1270                 if (fi->fib_nh->nh_lwtstate &&
1271                     lwtunnel_fill_encap(skb, fi->fib_nh->nh_lwtstate) < 0)
1272                         goto nla_put_failure;
1273         }
1274 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1275         if (fi->fib_nhs > 1) {
1276                 struct rtnexthop *rtnh;
1277                 struct nlattr *mp;
1278
1279                 mp = nla_nest_start(skb, RTA_MULTIPATH);
1280                 if (!mp)
1281                         goto nla_put_failure;
1282
1283                 for_nexthops(fi) {
1284                         struct in_device *in_dev;
1285
1286                         rtnh = nla_reserve_nohdr(skb, sizeof(*rtnh));
1287                         if (!rtnh)
1288                                 goto nla_put_failure;
1289
1290                         rtnh->rtnh_flags = nh->nh_flags & 0xFF;
1291                         if (nh->nh_flags & RTNH_F_LINKDOWN) {
1292                                 in_dev = __in_dev_get_rtnl(nh->nh_dev);
1293                                 if (in_dev &&
1294                                     IN_DEV_IGNORE_ROUTES_WITH_LINKDOWN(in_dev))
1295                                         rtnh->rtnh_flags |= RTNH_F_DEAD;
1296                         }
1297                         rtnh->rtnh_hops = nh->nh_weight - 1;
1298                         rtnh->rtnh_ifindex = nh->nh_oif;
1299
1300                         if (nh->nh_gw &&
1301                             nla_put_in_addr(skb, RTA_GATEWAY, nh->nh_gw))
1302                                 goto nla_put_failure;
1303 #ifdef CONFIG_IP_ROUTE_CLASSID
1304                         if (nh->nh_tclassid &&
1305                             nla_put_u32(skb, RTA_FLOW, nh->nh_tclassid))
1306                                 goto nla_put_failure;
1307 #endif
1308                         if (nh->nh_lwtstate &&
1309                             lwtunnel_fill_encap(skb, nh->nh_lwtstate) < 0)
1310                                 goto nla_put_failure;
1311
1312                         /* length of rtnetlink header + attributes */
1313                         rtnh->rtnh_len = nlmsg_get_pos(skb) - (void *) rtnh;
1314                 } endfor_nexthops(fi);
1315
1316                 nla_nest_end(skb, mp);
1317         }
1318 #endif
1319         nlmsg_end(skb, nlh);
1320         return 0;
1321
1322 nla_put_failure:
1323         nlmsg_cancel(skb, nlh);
1324         return -EMSGSIZE;
1325 }
1326
1327 /*
1328  * Update FIB if:
1329  * - local address disappeared -> we must delete all the entries
1330  *   referring to it.
1331  * - device went down -> we must shutdown all nexthops going via it.
1332  */
1333 int fib_sync_down_addr(struct net_device *dev, __be32 local)
1334 {
1335         int ret = 0;
1336         unsigned int hash = fib_laddr_hashfn(local);
1337         struct hlist_head *head = &fib_info_laddrhash[hash];
1338         struct net *net = dev_net(dev);
1339         int tb_id = l3mdev_fib_table(dev);
1340         struct fib_info *fi;
1341
1342         if (!fib_info_laddrhash || local == 0)
1343                 return 0;
1344
1345         hlist_for_each_entry(fi, head, fib_lhash) {
1346                 if (!net_eq(fi->fib_net, net) ||
1347                     fi->fib_tb_id != tb_id)
1348                         continue;
1349                 if (fi->fib_prefsrc == local) {
1350                         fi->fib_flags |= RTNH_F_DEAD;
1351                         ret++;
1352                 }
1353         }
1354         return ret;
1355 }
1356
1357 static int call_fib_nh_notifiers(struct fib_nh *fib_nh,
1358                                  enum fib_event_type event_type)
1359 {
1360         struct in_device *in_dev = __in_dev_get_rtnl(fib_nh->nh_dev);
1361         struct fib_nh_notifier_info info = {
1362                 .fib_nh = fib_nh,
1363         };
1364
1365         switch (event_type) {
1366         case FIB_EVENT_NH_ADD:
1367                 if (fib_nh->nh_flags & RTNH_F_DEAD)
1368                         break;
1369                 if (IN_DEV_IGNORE_ROUTES_WITH_LINKDOWN(in_dev) &&
1370                     fib_nh->nh_flags & RTNH_F_LINKDOWN)
1371                         break;
1372                 return call_fib_notifiers(dev_net(fib_nh->nh_dev), event_type,
1373                                           &info.info);
1374         case FIB_EVENT_NH_DEL:
1375                 if ((IN_DEV_IGNORE_ROUTES_WITH_LINKDOWN(in_dev) &&
1376                      fib_nh->nh_flags & RTNH_F_LINKDOWN) ||
1377                     (fib_nh->nh_flags & RTNH_F_DEAD))
1378                         return call_fib_notifiers(dev_net(fib_nh->nh_dev),
1379                                                   event_type, &info.info);
1380         default:
1381                 break;
1382         }
1383
1384         return NOTIFY_DONE;
1385 }
1386
1387 /* Event              force Flags           Description
1388  * NETDEV_CHANGE      0     LINKDOWN        Carrier OFF, not for scope host
1389  * NETDEV_DOWN        0     LINKDOWN|DEAD   Link down, not for scope host
1390  * NETDEV_DOWN        1     LINKDOWN|DEAD   Last address removed
1391  * NETDEV_UNREGISTER  1     LINKDOWN|DEAD   Device removed
1392  */
1393 int fib_sync_down_dev(struct net_device *dev, unsigned long event, bool force)
1394 {
1395         int ret = 0;
1396         int scope = RT_SCOPE_NOWHERE;
1397         struct fib_info *prev_fi = NULL;
1398         unsigned int hash = fib_devindex_hashfn(dev->ifindex);
1399         struct hlist_head *head = &fib_info_devhash[hash];
1400         struct fib_nh *nh;
1401
1402         if (force)
1403                 scope = -1;
1404
1405         hlist_for_each_entry(nh, head, nh_hash) {
1406                 struct fib_info *fi = nh->nh_parent;
1407                 int dead;
1408
1409                 BUG_ON(!fi->fib_nhs);
1410                 if (nh->nh_dev != dev || fi == prev_fi)
1411                         continue;
1412                 prev_fi = fi;
1413                 dead = 0;
1414                 change_nexthops(fi) {
1415                         if (nexthop_nh->nh_flags & RTNH_F_DEAD)
1416                                 dead++;
1417                         else if (nexthop_nh->nh_dev == dev &&
1418                                  nexthop_nh->nh_scope != scope) {
1419                                 switch (event) {
1420                                 case NETDEV_DOWN:
1421                                 case NETDEV_UNREGISTER:
1422                                         nexthop_nh->nh_flags |= RTNH_F_DEAD;
1423                                         /* fall through */
1424                                 case NETDEV_CHANGE:
1425                                         nexthop_nh->nh_flags |= RTNH_F_LINKDOWN;
1426                                         break;
1427                                 }
1428                                 call_fib_nh_notifiers(nexthop_nh,
1429                                                       FIB_EVENT_NH_DEL);
1430                                 dead++;
1431                         }
1432 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1433                         if (event == NETDEV_UNREGISTER &&
1434                             nexthop_nh->nh_dev == dev) {
1435                                 dead = fi->fib_nhs;
1436                                 break;
1437                         }
1438 #endif
1439                 } endfor_nexthops(fi)
1440                 if (dead == fi->fib_nhs) {
1441                         switch (event) {
1442                         case NETDEV_DOWN:
1443                         case NETDEV_UNREGISTER:
1444                                 fi->fib_flags |= RTNH_F_DEAD;
1445                                 /* fall through */
1446                         case NETDEV_CHANGE:
1447                                 fi->fib_flags |= RTNH_F_LINKDOWN;
1448                                 break;
1449                         }
1450                         ret++;
1451                 }
1452
1453                 fib_rebalance(fi);
1454         }
1455
1456         return ret;
1457 }
1458
1459 /* Must be invoked inside of an RCU protected region.  */
1460 static void fib_select_default(const struct flowi4 *flp, struct fib_result *res)
1461 {
1462         struct fib_info *fi = NULL, *last_resort = NULL;
1463         struct hlist_head *fa_head = res->fa_head;
1464         struct fib_table *tb = res->table;
1465         u8 slen = 32 - res->prefixlen;
1466         int order = -1, last_idx = -1;
1467         struct fib_alias *fa, *fa1 = NULL;
1468         u32 last_prio = res->fi->fib_priority;
1469         u8 last_tos = 0;
1470
1471         hlist_for_each_entry_rcu(fa, fa_head, fa_list) {
1472                 struct fib_info *next_fi = fa->fa_info;
1473
1474                 if (fa->fa_slen != slen)
1475                         continue;
1476                 if (fa->fa_tos && fa->fa_tos != flp->flowi4_tos)
1477                         continue;
1478                 if (fa->tb_id != tb->tb_id)
1479                         continue;
1480                 if (next_fi->fib_priority > last_prio &&
1481                     fa->fa_tos == last_tos) {
1482                         if (last_tos)
1483                                 continue;
1484                         break;
1485                 }
1486                 if (next_fi->fib_flags & RTNH_F_DEAD)
1487                         continue;
1488                 last_tos = fa->fa_tos;
1489                 last_prio = next_fi->fib_priority;
1490
1491                 if (next_fi->fib_scope != res->scope ||
1492                     fa->fa_type != RTN_UNICAST)
1493                         continue;
1494                 if (!next_fi->fib_nh[0].nh_gw ||
1495                     next_fi->fib_nh[0].nh_scope != RT_SCOPE_LINK)
1496                         continue;
1497
1498                 fib_alias_accessed(fa);
1499
1500                 if (!fi) {
1501                         if (next_fi != res->fi)
1502                                 break;
1503                         fa1 = fa;
1504                 } else if (!fib_detect_death(fi, order, &last_resort,
1505                                              &last_idx, fa1->fa_default)) {
1506                         fib_result_assign(res, fi);
1507                         fa1->fa_default = order;
1508                         goto out;
1509                 }
1510                 fi = next_fi;
1511                 order++;
1512         }
1513
1514         if (order <= 0 || !fi) {
1515                 if (fa1)
1516                         fa1->fa_default = -1;
1517                 goto out;
1518         }
1519
1520         if (!fib_detect_death(fi, order, &last_resort, &last_idx,
1521                               fa1->fa_default)) {
1522                 fib_result_assign(res, fi);
1523                 fa1->fa_default = order;
1524                 goto out;
1525         }
1526
1527         if (last_idx >= 0)
1528                 fib_result_assign(res, last_resort);
1529         fa1->fa_default = last_idx;
1530 out:
1531         return;
1532 }
1533
1534 /*
1535  * Dead device goes up. We wake up dead nexthops.
1536  * It takes sense only on multipath routes.
1537  */
1538 int fib_sync_up(struct net_device *dev, unsigned int nh_flags)
1539 {
1540         struct fib_info *prev_fi;
1541         unsigned int hash;
1542         struct hlist_head *head;
1543         struct fib_nh *nh;
1544         int ret;
1545
1546         if (!(dev->flags & IFF_UP))
1547                 return 0;
1548
1549         if (nh_flags & RTNH_F_DEAD) {
1550                 unsigned int flags = dev_get_flags(dev);
1551
1552                 if (flags & (IFF_RUNNING | IFF_LOWER_UP))
1553                         nh_flags |= RTNH_F_LINKDOWN;
1554         }
1555
1556         prev_fi = NULL;
1557         hash = fib_devindex_hashfn(dev->ifindex);
1558         head = &fib_info_devhash[hash];
1559         ret = 0;
1560
1561         hlist_for_each_entry(nh, head, nh_hash) {
1562                 struct fib_info *fi = nh->nh_parent;
1563                 int alive;
1564
1565                 BUG_ON(!fi->fib_nhs);
1566                 if (nh->nh_dev != dev || fi == prev_fi)
1567                         continue;
1568
1569                 prev_fi = fi;
1570                 alive = 0;
1571                 change_nexthops(fi) {
1572                         if (!(nexthop_nh->nh_flags & nh_flags)) {
1573                                 alive++;
1574                                 continue;
1575                         }
1576                         if (!nexthop_nh->nh_dev ||
1577                             !(nexthop_nh->nh_dev->flags & IFF_UP))
1578                                 continue;
1579                         if (nexthop_nh->nh_dev != dev ||
1580                             !__in_dev_get_rtnl(dev))
1581                                 continue;
1582                         alive++;
1583                         nexthop_nh->nh_flags &= ~nh_flags;
1584                         call_fib_nh_notifiers(nexthop_nh, FIB_EVENT_NH_ADD);
1585                 } endfor_nexthops(fi)
1586
1587                 if (alive > 0) {
1588                         fi->fib_flags &= ~nh_flags;
1589                         ret++;
1590                 }
1591
1592                 fib_rebalance(fi);
1593         }
1594
1595         return ret;
1596 }
1597
1598 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1599 static bool fib_good_nh(const struct fib_nh *nh)
1600 {
1601         int state = NUD_REACHABLE;
1602
1603         if (nh->nh_scope == RT_SCOPE_LINK) {
1604                 struct neighbour *n;
1605
1606                 rcu_read_lock_bh();
1607
1608                 n = __ipv4_neigh_lookup_noref(nh->nh_dev,
1609                                               (__force u32)nh->nh_gw);
1610                 if (n)
1611                         state = n->nud_state;
1612
1613                 rcu_read_unlock_bh();
1614         }
1615
1616         return !!(state & NUD_VALID);
1617 }
1618
1619 void fib_select_multipath(struct fib_result *res, int hash)
1620 {
1621         struct fib_info *fi = res->fi;
1622         struct net *net = fi->fib_net;
1623         bool first = false;
1624
1625         for_nexthops(fi) {
1626                 if (hash > atomic_read(&nh->nh_upper_bound))
1627                         continue;
1628
1629                 if (!net->ipv4.sysctl_fib_multipath_use_neigh ||
1630                     fib_good_nh(nh)) {
1631                         res->nh_sel = nhsel;
1632                         return;
1633                 }
1634                 if (!first) {
1635                         res->nh_sel = nhsel;
1636                         first = true;
1637                 }
1638         } endfor_nexthops(fi);
1639 }
1640 #endif
1641
1642 void fib_select_path(struct net *net, struct fib_result *res,
1643                      struct flowi4 *fl4, const struct sk_buff *skb)
1644 {
1645         bool oif_check;
1646
1647         oif_check = (fl4->flowi4_oif == 0 ||
1648                      fl4->flowi4_flags & FLOWI_FLAG_SKIP_NH_OIF);
1649
1650 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1651         if (res->fi->fib_nhs > 1 && oif_check) {
1652                 int h = fib_multipath_hash(res->fi, fl4, skb);
1653
1654                 fib_select_multipath(res, h);
1655         }
1656         else
1657 #endif
1658         if (!res->prefixlen &&
1659             res->table->tb_num_default > 1 &&
1660             res->type == RTN_UNICAST && oif_check)
1661                 fib_select_default(fl4, res);
1662
1663         if (!fl4->saddr)
1664                 fl4->saddr = FIB_RES_PREFSRC(net, *res);
1665 }
1666 EXPORT_SYMBOL_GPL(fib_select_path);