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