net/ipv4/fib_semantics.c

   1 /*
   2  * INET         An implementation of the TCP/IP protocol suite for the LINUX
   3  *              operating system.  INET is implemented using the  BSD Socket
   4  *              interface as the means of communication with the user level.
   5  *
   6  *              IPv4 Forwarding Information Base: semantics.
   7  *
   8  * Authors:     Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
   9  *
  10  *              This program is free software; you can redistribute it and/or
  11  *              modify it under the terms of the GNU General Public License
  12  *              as published by the Free Software Foundation; either version
  13  *              2 of the License, or (at your option) any later version.
  14  */
  15
  16 #include <asm/uaccess.h>
  17 #include <asm/system.h>
  18 #include <linux/bitops.h>
  19 #include <linux/types.h>
  20 #include <linux/kernel.h>
  21 #include <linux/jiffies.h>
  22 #include <linux/mm.h>
  23 #include <linux/string.h>
  24 #include <linux/socket.h>
  25 #include <linux/sockios.h>
  26 #include <linux/errno.h>
  27 #include <linux/in.h>
  28 #include <linux/inet.h>
  29 #include <linux/inetdevice.h>
  30 #include <linux/netdevice.h>
  31 #include <linux/if_arp.h>
  32 #include <linux/proc_fs.h>
  33 #include <linux/skbuff.h>
  34 #include <linux/init.h>
  35 #include <linux/slab.h>
  36
  37 #include <net/arp.h>
  38 #include <net/ip.h>
  39 #include <net/protocol.h>
  40 #include <net/route.h>
  41 #include <net/tcp.h>
  42 #include <net/sock.h>
  43 #include <net/ip_fib.h>
  44 #include <net/netlink.h>
  45 #include <net/nexthop.h>
  46
  47 #include "fib_lookup.h"
  48
  49 static DEFINE_SPINLOCK(fib_info_lock);
  50 static struct hlist_head *fib_info_hash;
  51 static struct hlist_head *fib_info_laddrhash;
  52 static unsigned int fib_info_hash_size;
  53 static unsigned int fib_info_cnt;
  54
  55 #define DEVINDEX_HASHBITS 8
  56 #define DEVINDEX_HASHSIZE (1U << DEVINDEX_HASHBITS)
  57 static struct hlist_head fib_info_devhash[DEVINDEX_HASHSIZE];
  58
  59 #ifdef CONFIG_IP_ROUTE_MULTIPATH
  60
  61 static DEFINE_SPINLOCK(fib_multipath_lock);
  62
  63 #define for_nexthops(fi) {                                              \
  64         int nhsel; const struct fib_nh *nh;                             \
  65         for (nhsel = 0, nh = (fi)->fib_nh;                              \
  66              nhsel < (fi)->fib_nhs;                                     \
  67              nh++, nhsel++)
  68
  69 #define change_nexthops(fi) {                                           \
  70         int nhsel; struct fib_nh *nexthop_nh;                           \
  71         for (nhsel = 0, nexthop_nh = (struct fib_nh *)((fi)->fib_nh);   \
  72              nhsel < (fi)->fib_nhs;                                     \
  73              nexthop_nh++, nhsel++)
  74
  75 #else /* CONFIG_IP_ROUTE_MULTIPATH */
  76
  77 /* Hope, that gcc will optimize it to get rid of dummy loop */
  78
  79 #define for_nexthops(fi) {                                              \
  80         int nhsel; const struct fib_nh *nh = (fi)->fib_nh;              \
  81         for (nhsel = 0; nhsel < 1; nhsel++)
  82
  83 #define change_nexthops(fi) {                                           \
  84         int nhsel;                                                      \
  85         struct fib_nh *nexthop_nh = (struct fib_nh *)((fi)->fib_nh);    \
  86         for (nhsel = 0; nhsel < 1; nhsel++)
  87
  88 #endif /* CONFIG_IP_ROUTE_MULTIPATH */
  89
  90 #define endfor_nexthops(fi) }
  91
  92
  93 const struct fib_prop fib_props[RTN_MAX + 1] = {
  94         [RTN_UNSPEC] = {
  95                 .error  = 0,
  96                 .scope  = RT_SCOPE_NOWHERE,
  97         },
  98         [RTN_UNICAST] = {
  99                 .error  = 0,
 100                 .scope  = RT_SCOPE_UNIVERSE,
 101         },
 102         [RTN_LOCAL] = {
 103                 .error  = 0,
 104                 .scope  = RT_SCOPE_HOST,
 105         },
 106         [RTN_BROADCAST] = {
 107                 .error  = 0,
 108                 .scope  = RT_SCOPE_LINK,
 109         },
 110         [RTN_ANYCAST] = {
 111                 .error  = 0,
 112                 .scope  = RT_SCOPE_LINK,
 113         },
 114         [RTN_MULTICAST] = {
 115                 .error  = 0,
 116                 .scope  = RT_SCOPE_UNIVERSE,
 117         },
 118         [RTN_BLACKHOLE] = {
 119                 .error  = -EINVAL,
 120                 .scope  = RT_SCOPE_UNIVERSE,
 121         },
 122         [RTN_UNREACHABLE] = {
 123                 .error  = -EHOSTUNREACH,
 124                 .scope  = RT_SCOPE_UNIVERSE,
 125         },
 126         [RTN_PROHIBIT] = {
 127                 .error  = -EACCES,
 128                 .scope  = RT_SCOPE_UNIVERSE,
 129         },
 130         [RTN_THROW] = {
 131                 .error  = -EAGAIN,
 132                 .scope  = RT_SCOPE_UNIVERSE,
 133         },
 134         [RTN_NAT] = {
 135                 .error  = -EINVAL,
 136                 .scope  = RT_SCOPE_NOWHERE,
 137         },
 138         [RTN_XRESOLVE] = {
 139                 .error  = -EINVAL,
 140                 .scope  = RT_SCOPE_NOWHERE,
 141         },
 142 };
 143
 144
 145 /* Release a nexthop info record */
 146
 147 static void free_fib_info_rcu(struct rcu_head *head)
 148 {
 149         struct fib_info *fi = container_of(head, struct fib_info, rcu);
 150
 151         if (fi->fib_metrics != (u32 *) dst_default_metrics)
 152                 kfree(fi->fib_metrics);
 153         kfree(fi);
 154 }
 155
 156 void free_fib_info(struct fib_info *fi)
 157 {
 158         if (fi->fib_dead == 0) {
 159                 pr_warning("Freeing alive fib_info %p\n", fi);
 160                 return;
 161         }
 162         change_nexthops(fi) {
 163                 if (nexthop_nh->nh_dev)
 164                         dev_put(nexthop_nh->nh_dev);
 165                 nexthop_nh->nh_dev = NULL;
 166         } endfor_nexthops(fi);
 167         fib_info_cnt--;
 168         release_net(fi->fib_net);
 169         call_rcu(&fi->rcu, free_fib_info_rcu);
 170 }
 171
 172 void fib_release_info(struct fib_info *fi)
 173 {
 174         spin_lock_bh(&fib_info_lock);
 175         if (fi && --fi->fib_treeref == 0) {
 176                 hlist_del(&fi->fib_hash);
 177                 if (fi->fib_prefsrc)
 178                         hlist_del(&fi->fib_lhash);
 179                 change_nexthops(fi) {
 180                         if (!nexthop_nh->nh_dev)
 181                                 continue;
 182                         hlist_del(&nexthop_nh->nh_hash);
 183                 } endfor_nexthops(fi)
 184                 fi->fib_dead = 1;
 185                 fib_info_put(fi);
 186         }
 187         spin_unlock_bh(&fib_info_lock);
 188 }
 189
 190 static inline int nh_comp(const struct fib_info *fi, const struct fib_info *ofi)
 191 {
 192         const struct fib_nh *onh = ofi->fib_nh;
 193
 194         for_nexthops(fi) {
 195                 if (nh->nh_oif != onh->nh_oif ||
 196                     nh->nh_gw  != onh->nh_gw ||
 197                     nh->nh_scope != onh->nh_scope ||
 198 #ifdef CONFIG_IP_ROUTE_MULTIPATH
 199                     nh->nh_weight != onh->nh_weight ||
 200 #endif
 201 #ifdef CONFIG_IP_ROUTE_CLASSID
 202                     nh->nh_tclassid != onh->nh_tclassid ||
 203 #endif
 204                     ((nh->nh_flags ^ onh->nh_flags) & ~RTNH_F_DEAD))
 205                         return -1;
 206                 onh++;
 207         } endfor_nexthops(fi);
 208         return 0;
 209 }
 210
 211 static inline unsigned int fib_devindex_hashfn(unsigned int val)
 212 {
 213         unsigned int mask = DEVINDEX_HASHSIZE - 1;
 214
 215         return (val ^
 216                 (val >> DEVINDEX_HASHBITS) ^
 217                 (val >> (DEVINDEX_HASHBITS * 2))) & mask;
 218 }
 219
 220 static inline unsigned int fib_info_hashfn(const struct fib_info *fi)
 221 {
 222         unsigned int mask = (fib_info_hash_size - 1);
 223         unsigned int val = fi->fib_nhs;
 224
 225         val ^= fi->fib_protocol;
 226         val ^= (__force u32)fi->fib_prefsrc;
 227         val ^= fi->fib_priority;
 228         for_nexthops(fi) {
 229                 val ^= fib_devindex_hashfn(nh->nh_oif);
 230         } endfor_nexthops(fi)
 231
 232         return (val ^ (val >> 7) ^ (val >> 12)) & mask;
 233 }
 234
 235 static struct fib_info *fib_find_info(const struct fib_info *nfi)
 236 {
 237         struct hlist_head *head;
 238         struct hlist_node *node;
 239         struct fib_info *fi;
 240         unsigned int hash;
 241
 242         hash = fib_info_hashfn(nfi);
 243         head = &fib_info_hash[hash];
 244
 245         hlist_for_each_entry(fi, node, head, fib_hash) {
 246                 if (!net_eq(fi->fib_net, nfi->fib_net))
 247                         continue;
 248                 if (fi->fib_nhs != nfi->fib_nhs)
 249                         continue;
 250                 if (nfi->fib_protocol == fi->fib_protocol &&
 251                     nfi->fib_prefsrc == fi->fib_prefsrc &&
 252                     nfi->fib_priority == fi->fib_priority &&
 253                     memcmp(nfi->fib_metrics, fi->fib_metrics,
 254                            sizeof(u32) * RTAX_MAX) == 0 &&
 255                     ((nfi->fib_flags ^ fi->fib_flags) & ~RTNH_F_DEAD) == 0 &&
 256                     (nfi->fib_nhs == 0 || nh_comp(fi, nfi) == 0))
 257                         return fi;
 258         }
 259
 260         return NULL;
 261 }
 262
 263 /* Check, that the gateway is already configured.
 264  * Used only by redirect accept routine.
 265  */
 266 int ip_fib_check_default(__be32 gw, struct net_device *dev)
 267 {
 268         struct hlist_head *head;
 269         struct hlist_node *node;
 270         struct fib_nh *nh;
 271         unsigned int hash;
 272
 273         spin_lock(&fib_info_lock);
 274
 275         hash = fib_devindex_hashfn(dev->ifindex);
 276         head = &fib_info_devhash[hash];
 277         hlist_for_each_entry(nh, node, head, nh_hash) {
 278                 if (nh->nh_dev == dev &&
 279                     nh->nh_gw == gw &&
 280                     !(nh->nh_flags & RTNH_F_DEAD)) {
 281                         spin_unlock(&fib_info_lock);
 282                         return 0;
 283                 }
 284         }
 285
 286         spin_unlock(&fib_info_lock);
 287
 288         return -1;
 289 }
 290
 291 static inline size_t fib_nlmsg_size(struct fib_info *fi)
 292 {
 293         size_t payload = NLMSG_ALIGN(sizeof(struct rtmsg))
 294                          + nla_total_size(4) /* RTA_TABLE */
 295                          + nla_total_size(4) /* RTA_DST */
 296                          + nla_total_size(4) /* RTA_PRIORITY */
 297                          + nla_total_size(4); /* RTA_PREFSRC */
 298
 299         /* space for nested metrics */
 300         payload += nla_total_size((RTAX_MAX * nla_total_size(4)));
 301
 302         if (fi->fib_nhs) {
 303                 /* Also handles the special case fib_nhs == 1 */
 304
 305                 /* each nexthop is packed in an attribute */
 306                 size_t nhsize = nla_total_size(sizeof(struct rtnexthop));
 307
 308                 /* may contain flow and gateway attribute */
 309                 nhsize += 2 * nla_total_size(4);
 310
 311                 /* all nexthops are packed in a nested attribute */
 312                 payload += nla_total_size(fi->fib_nhs * nhsize);
 313         }
 314
 315         return payload;
 316 }
 317
 318 void rtmsg_fib(int event, __be32 key, struct fib_alias *fa,
 319                int dst_len, u32 tb_id, struct nl_info *info,
 320                unsigned int nlm_flags)
 321 {
 322         struct sk_buff *skb;
 323         u32 seq = info->nlh ? info->nlh->nlmsg_seq : 0;
 324         int err = -ENOBUFS;
 325
 326         skb = nlmsg_new(fib_nlmsg_size(fa->fa_info), GFP_KERNEL);
 327         if (skb == NULL)
 328                 goto errout;
 329
 330         err = fib_dump_info(skb, info->pid, seq, event, tb_id,
 331                             fa->fa_type, fa->fa_scope, key, dst_len,
 332                             fa->fa_tos, fa->fa_info, nlm_flags);
 333         if (err < 0) {
 334                 /* -EMSGSIZE implies BUG in fib_nlmsg_size() */
 335                 WARN_ON(err == -EMSGSIZE);
 336                 kfree_skb(skb);
 337                 goto errout;
 338         }
 339         rtnl_notify(skb, info->nl_net, info->pid, RTNLGRP_IPV4_ROUTE,
 340                     info->nlh, GFP_KERNEL);
 341         return;
 342 errout:
 343         if (err < 0)
 344                 rtnl_set_sk_err(info->nl_net, RTNLGRP_IPV4_ROUTE, err);
 345 }
 346
 347 /* Return the first fib alias matching TOS with
 348  * priority less than or equal to PRIO.
 349  */
 350 struct fib_alias *fib_find_alias(struct list_head *fah, u8 tos, u32 prio)
 351 {
 352         if (fah) {
 353                 struct fib_alias *fa;
 354                 list_for_each_entry(fa, fah, fa_list) {
 355                         if (fa->fa_tos > tos)
 356                                 continue;
 357                         if (fa->fa_info->fib_priority >= prio ||
 358                             fa->fa_tos < tos)
 359                                 return fa;
 360                 }
 361         }
 362         return NULL;
 363 }
 364
 365 int fib_detect_death(struct fib_info *fi, int order,
 366                      struct fib_info **last_resort, int *last_idx, int dflt)
 367 {
 368         struct neighbour *n;
 369         int state = NUD_NONE;
 370
 371         n = neigh_lookup(&arp_tbl, &fi->fib_nh[0].nh_gw, fi->fib_dev);
 372         if (n) {
 373                 state = n->nud_state;
 374                 neigh_release(n);
 375         }
 376         if (state == NUD_REACHABLE)
 377                 return 0;
 378         if ((state & NUD_VALID) && order != dflt)
 379                 return 0;
 380         if ((state & NUD_VALID) ||
 381             (*last_idx < 0 && order > dflt)) {
 382                 *last_resort = fi;
 383                 *last_idx = order;
 384         }
 385         return 1;
 386 }
 387
 388 #ifdef CONFIG_IP_ROUTE_MULTIPATH
 389
 390 static int fib_count_nexthops(struct rtnexthop *rtnh, int remaining)
 391 {
 392         int nhs = 0;
 393
 394         while (rtnh_ok(rtnh, remaining)) {
 395                 nhs++;
 396                 rtnh = rtnh_next(rtnh, &remaining);
 397         }
 398
 399         /* leftover implies invalid nexthop configuration, discard it */
 400         return remaining > 0 ? 0 : nhs;
 401 }
 402
 403 static int fib_get_nhs(struct fib_info *fi, struct rtnexthop *rtnh,
 404                        int remaining, struct fib_config *cfg)
 405 {
 406         change_nexthops(fi) {
 407                 int attrlen;
 408
 409                 if (!rtnh_ok(rtnh, remaining))
 410                         return -EINVAL;
 411
 412                 nexthop_nh->nh_flags =
 413                         (cfg->fc_flags & ~0xFF) | rtnh->rtnh_flags;
 414                 nexthop_nh->nh_oif = rtnh->rtnh_ifindex;
 415                 nexthop_nh->nh_weight = rtnh->rtnh_hops + 1;
 416
 417                 attrlen = rtnh_attrlen(rtnh);
 418                 if (attrlen > 0) {
 419                         struct nlattr *nla, *attrs = rtnh_attrs(rtnh);
 420
 421                         nla = nla_find(attrs, attrlen, RTA_GATEWAY);
 422                         nexthop_nh->nh_gw = nla ? nla_get_be32(nla) : 0;
 423 #ifdef CONFIG_IP_ROUTE_CLASSID
 424                         nla = nla_find(attrs, attrlen, RTA_FLOW);
 425                         nexthop_nh->nh_tclassid = nla ? nla_get_u32(nla) : 0;
 426 #endif
 427                 }
 428
 429                 rtnh = rtnh_next(rtnh, &remaining);
 430         } endfor_nexthops(fi);
 431
 432         return 0;
 433 }
 434
 435 #endif
 436
 437 int fib_nh_match(struct fib_config *cfg, struct fib_info *fi)
 438 {
 439 #ifdef CONFIG_IP_ROUTE_MULTIPATH
 440         struct rtnexthop *rtnh;
 441         int remaining;
 442 #endif
 443
 444         if (cfg->fc_priority && cfg->fc_priority != fi->fib_priority)
 445                 return 1;
 446
 447         if (cfg->fc_oif || cfg->fc_gw) {
 448                 if ((!cfg->fc_oif || cfg->fc_oif == fi->fib_nh->nh_oif) &&
 449                     (!cfg->fc_gw  || cfg->fc_gw == fi->fib_nh->nh_gw))
 450                         return 0;
 451                 return 1;
 452         }
 453
 454 #ifdef CONFIG_IP_ROUTE_MULTIPATH
 455         if (cfg->fc_mp == NULL)
 456                 return 0;
 457
 458         rtnh = cfg->fc_mp;
 459         remaining = cfg->fc_mp_len;
 460
 461         for_nexthops(fi) {
 462                 int attrlen;
 463
 464                 if (!rtnh_ok(rtnh, remaining))
 465                         return -EINVAL;
 466
 467                 if (rtnh->rtnh_ifindex && rtnh->rtnh_ifindex != nh->nh_oif)
 468                         return 1;
 469
 470                 attrlen = rtnh_attrlen(rtnh);
 471                 if (attrlen < 0) {
 472                         struct nlattr *nla, *attrs = rtnh_attrs(rtnh);
 473
 474                         nla = nla_find(attrs, attrlen, RTA_GATEWAY);
 475                         if (nla && nla_get_be32(nla) != nh->nh_gw)
 476                                 return 1;
 477 #ifdef CONFIG_IP_ROUTE_CLASSID
 478                         nla = nla_find(attrs, attrlen, RTA_FLOW);
 479                         if (nla && nla_get_u32(nla) != nh->nh_tclassid)
 480                                 return 1;
 481 #endif
 482                 }
 483
 484                 rtnh = rtnh_next(rtnh, &remaining);
 485         } endfor_nexthops(fi);
 486 #endif
 487         return 0;
 488 }
 489
 490
 491 /*
 492  * Picture
 493  * -------
 494  *
 495  * Semantics of nexthop is very messy by historical reasons.
 496  * We have to take into account, that:
 497  * a) gateway can be actually local interface address,
 498  *    so that gatewayed route is direct.
 499  * b) gateway must be on-link address, possibly
 500  *    described not by an ifaddr, but also by a direct route.
 501  * c) If both gateway and interface are specified, they should not
 502  *    contradict.
 503  * d) If we use tunnel routes, gateway could be not on-link.
 504  *
 505  * Attempt to reconcile all of these (alas, self-contradictory) conditions
 506  * results in pretty ugly and hairy code with obscure logic.
 507  *
 508  * I chose to generalized it instead, so that the size
 509  * of code does not increase practically, but it becomes
 510  * much more general.
 511  * Every prefix is assigned a "scope" value: "host" is local address,
 512  * "link" is direct route,
 513  * [ ... "site" ... "interior" ... ]
 514  * and "universe" is true gateway route with global meaning.
 515  *
 516  * Every prefix refers to a set of "nexthop"s (gw, oif),
 517  * where gw must have narrower scope. This recursion stops
 518  * when gw has LOCAL scope or if "nexthop" is declared ONLINK,
 519  * which means that gw is forced to be on link.
 520  *
 521  * Code is still hairy, but now it is apparently logically
 522  * consistent and very flexible. F.e. as by-product it allows
 523  * to co-exists in peace independent exterior and interior
 524  * routing processes.
 525  *
 526  * Normally it looks as following.
 527  *
 528  * {universe prefix}  -> (gw, oif) [scope link]
 529  *                |
 530  *                |-> {link prefix} -> (gw, oif) [scope local]
 531  *                                      |
 532  *                                      |-> {local prefix} (terminal node)
 533  */
 534 static int fib_check_nh(struct fib_config *cfg, struct fib_info *fi,
 535                         struct fib_nh *nh)
 536 {
 537         int err;
 538         struct net *net;
 539         struct net_device *dev;
 540
 541         net = cfg->fc_nlinfo.nl_net;
 542         if (nh->nh_gw) {
 543                 struct fib_result res;
 544
 545                 if (nh->nh_flags & RTNH_F_ONLINK) {
 546
 547                         if (cfg->fc_scope >= RT_SCOPE_LINK)
 548                                 return -EINVAL;
 549                         if (inet_addr_type(net, nh->nh_gw) != RTN_UNICAST)
 550                                 return -EINVAL;
 551                         dev = __dev_get_by_index(net, nh->nh_oif);
 552                         if (!dev)
 553                                 return -ENODEV;
 554                         if (!(dev->flags & IFF_UP))
 555                                 return -ENETDOWN;
 556                         nh->nh_dev = dev;
 557                         dev_hold(dev);
 558                         nh->nh_scope = RT_SCOPE_LINK;
 559                         return 0;
 560                 }
 561                 rcu_read_lock();
 562                 {
 563                         struct flowi4 fl4 = {
 564                                 .daddr = nh->nh_gw,
 565                                 .flowi4_scope = cfg->fc_scope + 1,
 566                                 .flowi4_oif = nh->nh_oif,
 567                         };
 568
 569                         /* It is not necessary, but requires a bit of thinking */
 570                         if (fl4.flowi4_scope < RT_SCOPE_LINK)
 571                                 fl4.flowi4_scope = RT_SCOPE_LINK;
 572                         err = fib_lookup(net, &fl4, &res);
 573                         if (err) {
 574                                 rcu_read_unlock();
 575                                 return err;
 576                         }
 577                 }
 578                 err = -EINVAL;
 579                 if (res.type != RTN_UNICAST && res.type != RTN_LOCAL)
 580                         goto out;
 581                 nh->nh_scope = res.scope;
 582                 nh->nh_oif = FIB_RES_OIF(res);
 583                 nh->nh_dev = dev = FIB_RES_DEV(res);
 584                 if (!dev)
 585                         goto out;
 586                 dev_hold(dev);
 587                 err = (dev->flags & IFF_UP) ? 0 : -ENETDOWN;
 588         } else {
 589                 struct in_device *in_dev;
 590
 591                 if (nh->nh_flags & (RTNH_F_PERVASIVE | RTNH_F_ONLINK))
 592                         return -EINVAL;
 593
 594                 rcu_read_lock();
 595                 err = -ENODEV;
 596                 in_dev = inetdev_by_index(net, nh->nh_oif);
 597                 if (in_dev == NULL)
 598                         goto out;
 599                 err = -ENETDOWN;
 600                 if (!(in_dev->dev->flags & IFF_UP))
 601                         goto out;
 602                 nh->nh_dev = in_dev->dev;
 603                 dev_hold(nh->nh_dev);
 604                 nh->nh_scope = RT_SCOPE_HOST;
 605                 err = 0;
 606         }
 607 out:
 608         rcu_read_unlock();
 609         return err;
 610 }
 611
 612 static inline unsigned int fib_laddr_hashfn(__be32 val)
 613 {
 614         unsigned int mask = (fib_info_hash_size - 1);
 615
 616         return ((__force u32)val ^
 617                 ((__force u32)val >> 7) ^
 618                 ((__force u32)val >> 14)) & mask;
 619 }
 620
 621 static struct hlist_head *fib_info_hash_alloc(int bytes)
 622 {
 623         if (bytes <= PAGE_SIZE)
 624                 return kzalloc(bytes, GFP_KERNEL);
 625         else
 626                 return (struct hlist_head *)
 627                         __get_free_pages(GFP_KERNEL | __GFP_ZERO,
 628                                          get_order(bytes));
 629 }
 630
 631 static void fib_info_hash_free(struct hlist_head *hash, int bytes)
 632 {
 633         if (!hash)
 634                 return;
 635
 636         if (bytes <= PAGE_SIZE)
 637                 kfree(hash);
 638         else
 639                 free_pages((unsigned long) hash, get_order(bytes));
 640 }
 641
 642 static void fib_info_hash_move(struct hlist_head *new_info_hash,
 643                                struct hlist_head *new_laddrhash,
 644                                unsigned int new_size)
 645 {
 646         struct hlist_head *old_info_hash, *old_laddrhash;
 647         unsigned int old_size = fib_info_hash_size;
 648         unsigned int i, bytes;
 649
 650         spin_lock_bh(&fib_info_lock);
 651         old_info_hash = fib_info_hash;
 652         old_laddrhash = fib_info_laddrhash;
 653         fib_info_hash_size = new_size;
 654
 655         for (i = 0; i < old_size; i++) {
 656                 struct hlist_head *head = &fib_info_hash[i];
 657                 struct hlist_node *node, *n;
 658                 struct fib_info *fi;
 659
 660                 hlist_for_each_entry_safe(fi, node, n, head, fib_hash) {
 661                         struct hlist_head *dest;
 662                         unsigned int new_hash;
 663
 664                         hlist_del(&fi->fib_hash);
 665
 666                         new_hash = fib_info_hashfn(fi);
 667                         dest = &new_info_hash[new_hash];
 668                         hlist_add_head(&fi->fib_hash, dest);
 669                 }
 670         }
 671         fib_info_hash = new_info_hash;
 672
 673         for (i = 0; i < old_size; i++) {
 674                 struct hlist_head *lhead = &fib_info_laddrhash[i];
 675                 struct hlist_node *node, *n;
 676                 struct fib_info *fi;
 677
 678                 hlist_for_each_entry_safe(fi, node, n, lhead, fib_lhash) {
 679                         struct hlist_head *ldest;
 680                         unsigned int new_hash;
 681
 682                         hlist_del(&fi->fib_lhash);
 683
 684                         new_hash = fib_laddr_hashfn(fi->fib_prefsrc);
 685                         ldest = &new_laddrhash[new_hash];
 686                         hlist_add_head(&fi->fib_lhash, ldest);
 687                 }
 688         }
 689         fib_info_laddrhash = new_laddrhash;
 690
 691         spin_unlock_bh(&fib_info_lock);
 692
 693         bytes = old_size * sizeof(struct hlist_head *);
 694         fib_info_hash_free(old_info_hash, bytes);
 695         fib_info_hash_free(old_laddrhash, bytes);
 696 }
 697
 698 __be32 fib_info_update_nh_saddr(struct net *net, struct fib_nh *nh)
 699 {
 700         nh->nh_saddr = inet_select_addr(nh->nh_dev,
 701                                         nh->nh_gw,
 702                                         nh->nh_cfg_scope);
 703         nh->nh_saddr_genid = atomic_read(&net->ipv4.dev_addr_genid);
 704
 705         return nh->nh_saddr;
 706 }
 707
 708 struct fib_info *fib_create_info(struct fib_config *cfg)
 709 {
 710         int err;
 711         struct fib_info *fi = NULL;
 712         struct fib_info *ofi;
 713         int nhs = 1;
 714         struct net *net = cfg->fc_nlinfo.nl_net;
 715
 716         if (cfg->fc_type > RTN_MAX)
 717                 goto err_inval;
 718
 719         /* Fast check to catch the most weird cases */
 720         if (fib_props[cfg->fc_type].scope > cfg->fc_scope)
 721                 goto err_inval;
 722
 723 #ifdef CONFIG_IP_ROUTE_MULTIPATH
 724         if (cfg->fc_mp) {
 725                 nhs = fib_count_nexthops(cfg->fc_mp, cfg->fc_mp_len);
 726                 if (nhs == 0)
 727                         goto err_inval;
 728         }
 729 #endif
 730
 731         err = -ENOBUFS;
 732         if (fib_info_cnt >= fib_info_hash_size) {
 733                 unsigned int new_size = fib_info_hash_size << 1;
 734                 struct hlist_head *new_info_hash;
 735                 struct hlist_head *new_laddrhash;
 736                 unsigned int bytes;
 737
 738                 if (!new_size)
 739                         new_size = 1;
 740                 bytes = new_size * sizeof(struct hlist_head *);
 741                 new_info_hash = fib_info_hash_alloc(bytes);
 742                 new_laddrhash = fib_info_hash_alloc(bytes);
 743                 if (!new_info_hash || !new_laddrhash) {
 744                         fib_info_hash_free(new_info_hash, bytes);
 745                         fib_info_hash_free(new_laddrhash, bytes);
 746                 } else
 747                         fib_info_hash_move(new_info_hash, new_laddrhash, new_size);
 748
 749                 if (!fib_info_hash_size)
 750                         goto failure;
 751         }
 752
 753         fi = kzalloc(sizeof(*fi)+nhs*sizeof(struct fib_nh), GFP_KERNEL);
 754         if (fi == NULL)
 755                 goto failure;
 756         if (cfg->fc_mx) {
 757                 fi->fib_metrics = kzalloc(sizeof(u32) * RTAX_MAX, GFP_KERNEL);
 758                 if (!fi->fib_metrics)
 759                         goto failure;
 760         } else
 761                 fi->fib_metrics = (u32 *) dst_default_metrics;
 762         fib_info_cnt++;
 763
 764         fi->fib_net = hold_net(net);
 765         fi->fib_protocol = cfg->fc_protocol;
 766         fi->fib_flags = cfg->fc_flags;
 767         fi->fib_priority = cfg->fc_priority;
 768         fi->fib_prefsrc = cfg->fc_prefsrc;
 769
 770         fi->fib_nhs = nhs;
 771         change_nexthops(fi) {
 772                 nexthop_nh->nh_parent = fi;
 773         } endfor_nexthops(fi)
 774
 775         if (cfg->fc_mx) {
 776                 struct nlattr *nla;
 777                 int remaining;
 778
 779                 nla_for_each_attr(nla, cfg->fc_mx, cfg->fc_mx_len, remaining) {
 780                         int type = nla_type(nla);
 781
 782                         if (type) {
 783                                 if (type > RTAX_MAX)
 784                                         goto err_inval;
 785                                 fi->fib_metrics[type - 1] = nla_get_u32(nla);
 786                         }
 787                 }
 788         }
 789
 790         if (cfg->fc_mp) {
 791 #ifdef CONFIG_IP_ROUTE_MULTIPATH
 792                 err = fib_get_nhs(fi, cfg->fc_mp, cfg->fc_mp_len, cfg);
 793                 if (err != 0)
 794                         goto failure;
 795                 if (cfg->fc_oif && fi->fib_nh->nh_oif != cfg->fc_oif)
 796                         goto err_inval;
 797                 if (cfg->fc_gw && fi->fib_nh->nh_gw != cfg->fc_gw)
 798                         goto err_inval;
 799 #ifdef CONFIG_IP_ROUTE_CLASSID
 800                 if (cfg->fc_flow && fi->fib_nh->nh_tclassid != cfg->fc_flow)
 801                         goto err_inval;
 802 #endif
 803 #else
 804                 goto err_inval;
 805 #endif
 806         } else {
 807                 struct fib_nh *nh = fi->fib_nh;
 808
 809                 nh->nh_oif = cfg->fc_oif;
 810                 nh->nh_gw = cfg->fc_gw;
 811                 nh->nh_flags = cfg->fc_flags;
 812 #ifdef CONFIG_IP_ROUTE_CLASSID
 813                 nh->nh_tclassid = cfg->fc_flow;
 814 #endif
 815 #ifdef CONFIG_IP_ROUTE_MULTIPATH
 816                 nh->nh_weight = 1;
 817 #endif
 818         }
 819
 820         if (fib_props[cfg->fc_type].error) {
 821                 if (cfg->fc_gw || cfg->fc_oif || cfg->fc_mp)
 822                         goto err_inval;
 823                 goto link_it;
 824         } else {
 825                 switch (cfg->fc_type) {
 826                 case RTN_UNICAST:
 827                 case RTN_LOCAL:
 828                 case RTN_BROADCAST:
 829                 case RTN_ANYCAST:
 830                 case RTN_MULTICAST:
 831                         break;
 832                 default:
 833                         goto err_inval;
 834                 }
 835         }
 836
 837         if (cfg->fc_scope > RT_SCOPE_HOST)
 838                 goto err_inval;
 839
 840         if (cfg->fc_scope == RT_SCOPE_HOST) {
 841                 struct fib_nh *nh = fi->fib_nh;
 842
 843                 /* Local address is added. */
 844                 if (nhs != 1 || nh->nh_gw)
 845                         goto err_inval;
 846                 nh->nh_scope = RT_SCOPE_NOWHERE;
 847                 nh->nh_dev = dev_get_by_index(net, fi->fib_nh->nh_oif);
 848                 err = -ENODEV;
 849                 if (nh->nh_dev == NULL)
 850                         goto failure;
 851         } else {
 852                 change_nexthops(fi) {
 853                         err = fib_check_nh(cfg, fi, nexthop_nh);
 854                         if (err != 0)
 855                                 goto failure;
 856                 } endfor_nexthops(fi)
 857         }
 858
 859         if (fi->fib_prefsrc) {
 860                 if (cfg->fc_type != RTN_LOCAL || !cfg->fc_dst ||
 861                     fi->fib_prefsrc != cfg->fc_dst)
 862                         if (inet_addr_type(net, fi->fib_prefsrc) != RTN_LOCAL)
 863                                 goto err_inval;
 864         }
 865
 866         change_nexthops(fi) {
 867                 nexthop_nh->nh_cfg_scope = cfg->fc_scope;
 868                 fib_info_update_nh_saddr(net, nexthop_nh);
 869         } endfor_nexthops(fi)
 870
 871 link_it:
 872         ofi = fib_find_info(fi);
 873         if (ofi) {
 874                 fi->fib_dead = 1;
 875                 free_fib_info(fi);
 876                 ofi->fib_treeref++;
 877                 return ofi;
 878         }
 879
 880         fi->fib_treeref++;
 881         atomic_inc(&fi->fib_clntref);
 882         spin_lock_bh(&fib_info_lock);
 883         hlist_add_head(&fi->fib_hash,
 884                        &fib_info_hash[fib_info_hashfn(fi)]);
 885         if (fi->fib_prefsrc) {
 886                 struct hlist_head *head;
 887
 888                 head = &fib_info_laddrhash[fib_laddr_hashfn(fi->fib_prefsrc)];
 889                 hlist_add_head(&fi->fib_lhash, head);
 890         }
 891         change_nexthops(fi) {
 892                 struct hlist_head *head;
 893                 unsigned int hash;
 894
 895                 if (!nexthop_nh->nh_dev)
 896                         continue;
 897                 hash = fib_devindex_hashfn(nexthop_nh->nh_dev->ifindex);
 898                 head = &fib_info_devhash[hash];
 899                 hlist_add_head(&nexthop_nh->nh_hash, head);
 900         } endfor_nexthops(fi)
 901         spin_unlock_bh(&fib_info_lock);
 902         return fi;
 903
 904 err_inval:
 905         err = -EINVAL;
 906
 907 failure:
 908         if (fi) {
 909                 fi->fib_dead = 1;
 910                 free_fib_info(fi);
 911         }
 912
 913         return ERR_PTR(err);
 914 }
 915
 916 int fib_dump_info(struct sk_buff *skb, u32 pid, u32 seq, int event,
 917                   u32 tb_id, u8 type, u8 scope, __be32 dst, int dst_len, u8 tos,
 918                   struct fib_info *fi, unsigned int flags)
 919 {
 920         struct nlmsghdr *nlh;
 921         struct rtmsg *rtm;
 922
 923         nlh = nlmsg_put(skb, pid, seq, event, sizeof(*rtm), flags);
 924         if (nlh == NULL)
 925                 return -EMSGSIZE;
 926
 927         rtm = nlmsg_data(nlh);
 928         rtm->rtm_family = AF_INET;
 929         rtm->rtm_dst_len = dst_len;
 930         rtm->rtm_src_len = 0;
 931         rtm->rtm_tos = tos;
 932         if (tb_id < 256)
 933                 rtm->rtm_table = tb_id;
 934         else
 935                 rtm->rtm_table = RT_TABLE_COMPAT;
 936         NLA_PUT_U32(skb, RTA_TABLE, tb_id);
 937         rtm->rtm_type = type;
 938         rtm->rtm_flags = fi->fib_flags;
 939         rtm->rtm_scope = scope;
 940         rtm->rtm_protocol = fi->fib_protocol;
 941
 942         if (rtm->rtm_dst_len)
 943                 NLA_PUT_BE32(skb, RTA_DST, dst);
 944
 945         if (fi->fib_priority)
 946                 NLA_PUT_U32(skb, RTA_PRIORITY, fi->fib_priority);
 947
 948         if (rtnetlink_put_metrics(skb, fi->fib_metrics) < 0)
 949                 goto nla_put_failure;
 950
 951         if (fi->fib_prefsrc)
 952                 NLA_PUT_BE32(skb, RTA_PREFSRC, fi->fib_prefsrc);
 953
 954         if (fi->fib_nhs == 1) {
 955                 if (fi->fib_nh->nh_gw)
 956                         NLA_PUT_BE32(skb, RTA_GATEWAY, fi->fib_nh->nh_gw);
 957
 958                 if (fi->fib_nh->nh_oif)
 959                         NLA_PUT_U32(skb, RTA_OIF, fi->fib_nh->nh_oif);
 960 #ifdef CONFIG_IP_ROUTE_CLASSID
 961                 if (fi->fib_nh[0].nh_tclassid)
 962                         NLA_PUT_U32(skb, RTA_FLOW, fi->fib_nh[0].nh_tclassid);
 963 #endif
 964         }
 965 #ifdef CONFIG_IP_ROUTE_MULTIPATH
 966         if (fi->fib_nhs > 1) {
 967                 struct rtnexthop *rtnh;
 968                 struct nlattr *mp;
 969
 970                 mp = nla_nest_start(skb, RTA_MULTIPATH);
 971                 if (mp == NULL)
 972                         goto nla_put_failure;
 973
 974                 for_nexthops(fi) {
 975                         rtnh = nla_reserve_nohdr(skb, sizeof(*rtnh));
 976                         if (rtnh == NULL)
 977                                 goto nla_put_failure;
 978
 979                         rtnh->rtnh_flags = nh->nh_flags & 0xFF;
 980                         rtnh->rtnh_hops = nh->nh_weight - 1;
 981                         rtnh->rtnh_ifindex = nh->nh_oif;
 982
 983                         if (nh->nh_gw)
 984                                 NLA_PUT_BE32(skb, RTA_GATEWAY, nh->nh_gw);
 985 #ifdef CONFIG_IP_ROUTE_CLASSID
 986                         if (nh->nh_tclassid)
 987                                 NLA_PUT_U32(skb, RTA_FLOW, nh->nh_tclassid);
 988 #endif
 989                         /* length of rtnetlink header + attributes */
 990                         rtnh->rtnh_len = nlmsg_get_pos(skb) - (void *) rtnh;
 991                 } endfor_nexthops(fi);
 992
 993                 nla_nest_end(skb, mp);
 994         }
 995 #endif
 996         return nlmsg_end(skb, nlh);
 997
 998 nla_put_failure:
 999         nlmsg_cancel(skb, nlh);
1000         return -EMSGSIZE;
1001 }
1002
1003 /*
1004  * Update FIB if:
1005  * - local address disappeared -> we must delete all the entries
1006  *   referring to it.
1007  * - device went down -> we must shutdown all nexthops going via it.
1008  */
1009 int fib_sync_down_addr(struct net *net, __be32 local)
1010 {
1011         int ret = 0;
1012         unsigned int hash = fib_laddr_hashfn(local);
1013         struct hlist_head *head = &fib_info_laddrhash[hash];
1014         struct hlist_node *node;
1015         struct fib_info *fi;
1016
1017         if (fib_info_laddrhash == NULL || local == 0)
1018                 return 0;
1019
1020         hlist_for_each_entry(fi, node, head, fib_lhash) {
1021                 if (!net_eq(fi->fib_net, net))
1022                         continue;
1023                 if (fi->fib_prefsrc == local) {
1024                         fi->fib_flags |= RTNH_F_DEAD;
1025                         ret++;
1026                 }
1027         }
1028         return ret;
1029 }
1030
1031 int fib_sync_down_dev(struct net_device *dev, int force)
1032 {
1033         int ret = 0;
1034         int scope = RT_SCOPE_NOWHERE;
1035         struct fib_info *prev_fi = NULL;
1036         unsigned int hash = fib_devindex_hashfn(dev->ifindex);
1037         struct hlist_head *head = &fib_info_devhash[hash];
1038         struct hlist_node *node;
1039         struct fib_nh *nh;
1040
1041         if (force)
1042                 scope = -1;
1043
1044         hlist_for_each_entry(nh, node, head, nh_hash) {
1045                 struct fib_info *fi = nh->nh_parent;
1046                 int dead;
1047
1048                 BUG_ON(!fi->fib_nhs);
1049                 if (nh->nh_dev != dev || fi == prev_fi)
1050                         continue;
1051                 prev_fi = fi;
1052                 dead = 0;
1053                 change_nexthops(fi) {
1054                         if (nexthop_nh->nh_flags & RTNH_F_DEAD)
1055                                 dead++;
1056                         else if (nexthop_nh->nh_dev == dev &&
1057                                  nexthop_nh->nh_scope != scope) {
1058                                 nexthop_nh->nh_flags |= RTNH_F_DEAD;
1059 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1060                                 spin_lock_bh(&fib_multipath_lock);
1061                                 fi->fib_power -= nexthop_nh->nh_power;
1062                                 nexthop_nh->nh_power = 0;
1063                                 spin_unlock_bh(&fib_multipath_lock);
1064 #endif
1065                                 dead++;
1066                         }
1067 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1068                         if (force > 1 && nexthop_nh->nh_dev == dev) {
1069                                 dead = fi->fib_nhs;
1070                                 break;
1071                         }
1072 #endif
1073                 } endfor_nexthops(fi)
1074                 if (dead == fi->fib_nhs) {
1075                         fi->fib_flags |= RTNH_F_DEAD;
1076                         ret++;
1077                 }
1078         }
1079
1080         return ret;
1081 }
1082
1083 /* Must be invoked inside of an RCU protected region.  */
1084 void fib_select_default(struct fib_result *res)
1085 {
1086         struct fib_info *fi = NULL, *last_resort = NULL;
1087         struct list_head *fa_head = res->fa_head;
1088         struct fib_table *tb = res->table;
1089         int order = -1, last_idx = -1;
1090         struct fib_alias *fa;
1091
1092         list_for_each_entry_rcu(fa, fa_head, fa_list) {
1093                 struct fib_info *next_fi = fa->fa_info;
1094
1095                 if (fa->fa_scope != res->scope ||
1096                     fa->fa_type != RTN_UNICAST)
1097                         continue;
1098
1099                 if (next_fi->fib_priority > res->fi->fib_priority)
1100                         break;
1101                 if (!next_fi->fib_nh[0].nh_gw ||
1102                     next_fi->fib_nh[0].nh_scope != RT_SCOPE_LINK)
1103                         continue;
1104
1105                 fib_alias_accessed(fa);
1106
1107                 if (fi == NULL) {
1108                         if (next_fi != res->fi)
1109                                 break;
1110                 } else if (!fib_detect_death(fi, order, &last_resort,
1111                                              &last_idx, tb->tb_default)) {
1112                         fib_result_assign(res, fi);
1113                         tb->tb_default = order;
1114                         goto out;
1115                 }
1116                 fi = next_fi;
1117                 order++;
1118         }
1119
1120         if (order <= 0 || fi == NULL) {
1121                 tb->tb_default = -1;
1122                 goto out;
1123         }
1124
1125         if (!fib_detect_death(fi, order, &last_resort, &last_idx,
1126                                 tb->tb_default)) {
1127                 fib_result_assign(res, fi);
1128                 tb->tb_default = order;
1129                 goto out;
1130         }
1131
1132         if (last_idx >= 0)
1133                 fib_result_assign(res, last_resort);
1134         tb->tb_default = last_idx;
1135 out:
1136         return;
1137 }
1138
1139 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1140
1141 /*
1142  * Dead device goes up. We wake up dead nexthops.
1143  * It takes sense only on multipath routes.
1144  */
1145 int fib_sync_up(struct net_device *dev)
1146 {
1147         struct fib_info *prev_fi;
1148         unsigned int hash;
1149         struct hlist_head *head;
1150         struct hlist_node *node;
1151         struct fib_nh *nh;
1152         int ret;
1153
1154         if (!(dev->flags & IFF_UP))
1155                 return 0;
1156
1157         prev_fi = NULL;
1158         hash = fib_devindex_hashfn(dev->ifindex);
1159         head = &fib_info_devhash[hash];
1160         ret = 0;
1161
1162         hlist_for_each_entry(nh, node, head, nh_hash) {
1163                 struct fib_info *fi = nh->nh_parent;
1164                 int alive;
1165
1166                 BUG_ON(!fi->fib_nhs);
1167                 if (nh->nh_dev != dev || fi == prev_fi)
1168                         continue;
1169
1170                 prev_fi = fi;
1171                 alive = 0;
1172                 change_nexthops(fi) {
1173                         if (!(nexthop_nh->nh_flags & RTNH_F_DEAD)) {
1174                                 alive++;
1175                                 continue;
1176                         }
1177                         if (nexthop_nh->nh_dev == NULL ||
1178                             !(nexthop_nh->nh_dev->flags & IFF_UP))
1179                                 continue;
1180                         if (nexthop_nh->nh_dev != dev ||
1181                             !__in_dev_get_rtnl(dev))
1182                                 continue;
1183                         alive++;
1184                         spin_lock_bh(&fib_multipath_lock);
1185                         nexthop_nh->nh_power = 0;
1186                         nexthop_nh->nh_flags &= ~RTNH_F_DEAD;
1187                         spin_unlock_bh(&fib_multipath_lock);
1188                 } endfor_nexthops(fi)
1189
1190                 if (alive > 0) {
1191                         fi->fib_flags &= ~RTNH_F_DEAD;
1192                         ret++;
1193                 }
1194         }
1195
1196         return ret;
1197 }
1198
1199 /*
1200  * The algorithm is suboptimal, but it provides really
1201  * fair weighted route distribution.
1202  */
1203 void fib_select_multipath(struct fib_result *res)
1204 {
1205         struct fib_info *fi = res->fi;
1206         int w;
1207
1208         spin_lock_bh(&fib_multipath_lock);
1209         if (fi->fib_power <= 0) {
1210                 int power = 0;
1211                 change_nexthops(fi) {
1212                         if (!(nexthop_nh->nh_flags & RTNH_F_DEAD)) {
1213                                 power += nexthop_nh->nh_weight;
1214                                 nexthop_nh->nh_power = nexthop_nh->nh_weight;
1215                         }
1216                 } endfor_nexthops(fi);
1217                 fi->fib_power = power;
1218                 if (power <= 0) {
1219                         spin_unlock_bh(&fib_multipath_lock);
1220                         /* Race condition: route has just become dead. */
1221                         res->nh_sel = 0;
1222                         return;
1223                 }
1224         }
1225
1226
1227         /* w should be random number [0..fi->fib_power-1],
1228          * it is pretty bad approximation.
1229          */
1230
1231         w = jiffies % fi->fib_power;
1232
1233         change_nexthops(fi) {
1234                 if (!(nexthop_nh->nh_flags & RTNH_F_DEAD) &&
1235                     nexthop_nh->nh_power) {
1236                         w -= nexthop_nh->nh_power;
1237                         if (w <= 0) {
1238                                 nexthop_nh->nh_power--;
1239                                 fi->fib_power--;
1240                                 res->nh_sel = nhsel;
1241                                 spin_unlock_bh(&fib_multipath_lock);
1242                                 return;
1243                         }
1244                 }
1245         } endfor_nexthops(fi);
1246
1247         /* Race condition: route has just become dead. */
1248         res->nh_sel = 0;
1249         spin_unlock_bh(&fib_multipath_lock);
1250 }
1251 #endif