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
  36 #include <net/arp.h>
  37 #include <net/ip.h>
  38 #include <net/protocol.h>
  39 #include <net/route.h>
  40 #include <net/tcp.h>
  41 #include <net/sock.h>
  42 #include <net/ip_fib.h>
  43 #include <net/netlink.h>
  44 #include <net/nexthop.h>
  45
  46 #include "fib_lookup.h"
  47
  48 static DEFINE_SPINLOCK(fib_info_lock);
  49 static struct hlist_head *fib_info_hash;
  50 static struct hlist_head *fib_info_laddrhash;
  51 static unsigned int fib_hash_size;
  52 static unsigned int fib_info_cnt;
  53
  54 #define DEVINDEX_HASHBITS 8
  55 #define DEVINDEX_HASHSIZE (1U << DEVINDEX_HASHBITS)
  56 static struct hlist_head fib_info_devhash[DEVINDEX_HASHSIZE];
  57
  58 #ifdef CONFIG_IP_ROUTE_MULTIPATH
  59
  60 static DEFINE_SPINLOCK(fib_multipath_lock);
  61
  62 #define for_nexthops(fi) { int nhsel; const struct fib_nh * nh; \
  63 for (nhsel=0, nh = (fi)->fib_nh; nhsel < (fi)->fib_nhs; nh++, nhsel++)
  64
  65 #define change_nexthops(fi) { int nhsel; struct fib_nh * nh; \
  66 for (nhsel=0, nh = (struct fib_nh *)((fi)->fib_nh); nhsel < (fi)->fib_nhs; nh++, nhsel++)
  67
  68 #else /* CONFIG_IP_ROUTE_MULTIPATH */
  69
  70 /* Hope, that gcc will optimize it to get rid of dummy loop */
  71
  72 #define for_nexthops(fi) { int nhsel = 0; const struct fib_nh * nh = (fi)->fib_nh; \
  73 for (nhsel=0; nhsel < 1; nhsel++)
  74
  75 #define change_nexthops(fi) { int nhsel = 0; struct fib_nh * nh = (struct fib_nh *)((fi)->fib_nh); \
  76 for (nhsel=0; nhsel < 1; nhsel++)
  77
  78 #endif /* CONFIG_IP_ROUTE_MULTIPATH */
  79
  80 #define endfor_nexthops(fi) }
  81
  82
  83 static const struct
  84 {
  85         int     error;
  86         u8      scope;
  87 } fib_props[RTN_MAX + 1] = {
  88         {
  89                 .error  = 0,
  90                 .scope  = RT_SCOPE_NOWHERE,
  91         },      /* RTN_UNSPEC */
  92         {
  93                 .error  = 0,
  94                 .scope  = RT_SCOPE_UNIVERSE,
  95         },      /* RTN_UNICAST */
  96         {
  97                 .error  = 0,
  98                 .scope  = RT_SCOPE_HOST,
  99         },      /* RTN_LOCAL */
 100         {
 101                 .error  = 0,
 102                 .scope  = RT_SCOPE_LINK,
 103         },      /* RTN_BROADCAST */
 104         {
 105                 .error  = 0,
 106                 .scope  = RT_SCOPE_LINK,
 107         },      /* RTN_ANYCAST */
 108         {
 109                 .error  = 0,
 110                 .scope  = RT_SCOPE_UNIVERSE,
 111         },      /* RTN_MULTICAST */
 112         {
 113                 .error  = -EINVAL,
 114                 .scope  = RT_SCOPE_UNIVERSE,
 115         },      /* RTN_BLACKHOLE */
 116         {
 117                 .error  = -EHOSTUNREACH,
 118                 .scope  = RT_SCOPE_UNIVERSE,
 119         },      /* RTN_UNREACHABLE */
 120         {
 121                 .error  = -EACCES,
 122                 .scope  = RT_SCOPE_UNIVERSE,
 123         },      /* RTN_PROHIBIT */
 124         {
 125                 .error  = -EAGAIN,
 126                 .scope  = RT_SCOPE_UNIVERSE,
 127         },      /* RTN_THROW */
 128         {
 129                 .error  = -EINVAL,
 130                 .scope  = RT_SCOPE_NOWHERE,
 131         },      /* RTN_NAT */
 132         {
 133                 .error  = -EINVAL,
 134                 .scope  = RT_SCOPE_NOWHERE,
 135         },      /* RTN_XRESOLVE */
 136 };
 137
 138
 139 /* Release a nexthop info record */
 140
 141 void free_fib_info(struct fib_info *fi)
 142 {
 143         if (fi->fib_dead == 0) {
 144                 printk(KERN_WARNING "Freeing alive fib_info %p\n", fi);
 145                 return;
 146         }
 147         change_nexthops(fi) {
 148                 if (nh->nh_dev)
 149                         dev_put(nh->nh_dev);
 150                 nh->nh_dev = NULL;
 151         } endfor_nexthops(fi);
 152         fib_info_cnt--;
 153         release_net(fi->fib_net);
 154         kfree(fi);
 155 }
 156
 157 void fib_release_info(struct fib_info *fi)
 158 {
 159         spin_lock_bh(&fib_info_lock);
 160         if (fi && --fi->fib_treeref == 0) {
 161                 hlist_del(&fi->fib_hash);
 162                 if (fi->fib_prefsrc)
 163                         hlist_del(&fi->fib_lhash);
 164                 change_nexthops(fi) {
 165                         if (!nh->nh_dev)
 166                                 continue;
 167                         hlist_del(&nh->nh_hash);
 168                 } endfor_nexthops(fi)
 169                 fi->fib_dead = 1;
 170                 fib_info_put(fi);
 171         }
 172         spin_unlock_bh(&fib_info_lock);
 173 }
 174
 175 static __inline__ int nh_comp(const struct fib_info *fi, const struct fib_info *ofi)
 176 {
 177         const struct fib_nh *onh = ofi->fib_nh;
 178
 179         for_nexthops(fi) {
 180                 if (nh->nh_oif != onh->nh_oif ||
 181                     nh->nh_gw  != onh->nh_gw ||
 182                     nh->nh_scope != onh->nh_scope ||
 183 #ifdef CONFIG_IP_ROUTE_MULTIPATH
 184                     nh->nh_weight != onh->nh_weight ||
 185 #endif
 186 #ifdef CONFIG_NET_CLS_ROUTE
 187                     nh->nh_tclassid != onh->nh_tclassid ||
 188 #endif
 189                     ((nh->nh_flags^onh->nh_flags)&~RTNH_F_DEAD))
 190                         return -1;
 191                 onh++;
 192         } endfor_nexthops(fi);
 193         return 0;
 194 }
 195
 196 static inline unsigned int fib_devindex_hashfn(unsigned int val)
 197 {
 198         unsigned int mask = DEVINDEX_HASHSIZE - 1;
 199
 200         return (val ^
 201                 (val >> DEVINDEX_HASHBITS) ^
 202                 (val >> (DEVINDEX_HASHBITS * 2))) & mask;
 203 }
 204
 205 static inline unsigned int fib_info_hashfn(const struct fib_info *fi)
 206 {
 207         unsigned int mask = (fib_hash_size - 1);
 208         unsigned int val = fi->fib_nhs;
 209
 210         val ^= fi->fib_protocol;
 211         val ^= (__force u32)fi->fib_prefsrc;
 212         val ^= fi->fib_priority;
 213         for_nexthops(fi) {
 214                 val ^= fib_devindex_hashfn(nh->nh_oif);
 215         } endfor_nexthops(fi)
 216
 217         return (val ^ (val >> 7) ^ (val >> 12)) & mask;
 218 }
 219
 220 static struct fib_info *fib_find_info(const struct fib_info *nfi)
 221 {
 222         struct hlist_head *head;
 223         struct hlist_node *node;
 224         struct fib_info *fi;
 225         unsigned int hash;
 226
 227         hash = fib_info_hashfn(nfi);
 228         head = &fib_info_hash[hash];
 229
 230         hlist_for_each_entry(fi, node, head, fib_hash) {
 231                 if (fi->fib_net != nfi->fib_net)
 232                         continue;
 233                 if (fi->fib_nhs != nfi->fib_nhs)
 234                         continue;
 235                 if (nfi->fib_protocol == fi->fib_protocol &&
 236                     nfi->fib_prefsrc == fi->fib_prefsrc &&
 237                     nfi->fib_priority == fi->fib_priority &&
 238                     memcmp(nfi->fib_metrics, fi->fib_metrics,
 239                            sizeof(fi->fib_metrics)) == 0 &&
 240                     ((nfi->fib_flags^fi->fib_flags)&~RTNH_F_DEAD) == 0 &&
 241                     (nfi->fib_nhs == 0 || nh_comp(fi, nfi) == 0))
 242                         return fi;
 243         }
 244
 245         return NULL;
 246 }
 247
 248 /* Check, that the gateway is already configured.
 249    Used only by redirect accept routine.
 250  */
 251
 252 int ip_fib_check_default(__be32 gw, struct net_device *dev)
 253 {
 254         struct hlist_head *head;
 255         struct hlist_node *node;
 256         struct fib_nh *nh;
 257         unsigned int hash;
 258
 259         spin_lock(&fib_info_lock);
 260
 261         hash = fib_devindex_hashfn(dev->ifindex);
 262         head = &fib_info_devhash[hash];
 263         hlist_for_each_entry(nh, node, head, nh_hash) {
 264                 if (nh->nh_dev == dev &&
 265                     nh->nh_gw == gw &&
 266                     !(nh->nh_flags&RTNH_F_DEAD)) {
 267                         spin_unlock(&fib_info_lock);
 268                         return 0;
 269                 }
 270         }
 271
 272         spin_unlock(&fib_info_lock);
 273
 274         return -1;
 275 }
 276
 277 static inline size_t fib_nlmsg_size(struct fib_info *fi)
 278 {
 279         size_t payload = NLMSG_ALIGN(sizeof(struct rtmsg))
 280                          + nla_total_size(4) /* RTA_TABLE */
 281                          + nla_total_size(4) /* RTA_DST */
 282                          + nla_total_size(4) /* RTA_PRIORITY */
 283                          + nla_total_size(4); /* RTA_PREFSRC */
 284
 285         /* space for nested metrics */
 286         payload += nla_total_size((RTAX_MAX * nla_total_size(4)));
 287
 288         if (fi->fib_nhs) {
 289                 /* Also handles the special case fib_nhs == 1 */
 290
 291                 /* each nexthop is packed in an attribute */
 292                 size_t nhsize = nla_total_size(sizeof(struct rtnexthop));
 293
 294                 /* may contain flow and gateway attribute */
 295                 nhsize += 2 * nla_total_size(4);
 296
 297                 /* all nexthops are packed in a nested attribute */
 298                 payload += nla_total_size(fi->fib_nhs * nhsize);
 299         }
 300
 301         return payload;
 302 }
 303
 304 void rtmsg_fib(int event, __be32 key, struct fib_alias *fa,
 305                int dst_len, u32 tb_id, struct nl_info *info,
 306                unsigned int nlm_flags)
 307 {
 308         struct sk_buff *skb;
 309         u32 seq = info->nlh ? info->nlh->nlmsg_seq : 0;
 310         int err = -ENOBUFS;
 311
 312         skb = nlmsg_new(fib_nlmsg_size(fa->fa_info), GFP_KERNEL);
 313         if (skb == NULL)
 314                 goto errout;
 315
 316         err = fib_dump_info(skb, info->pid, seq, event, tb_id,
 317                             fa->fa_type, fa->fa_scope, key, dst_len,
 318                             fa->fa_tos, fa->fa_info, nlm_flags);
 319         if (err < 0) {
 320                 /* -EMSGSIZE implies BUG in fib_nlmsg_size() */
 321                 WARN_ON(err == -EMSGSIZE);
 322                 kfree_skb(skb);
 323                 goto errout;
 324         }
 325         rtnl_notify(skb, info->nl_net, info->pid, RTNLGRP_IPV4_ROUTE,
 326                     info->nlh, GFP_KERNEL);
 327         return;
 328 errout:
 329         if (err < 0)
 330                 rtnl_set_sk_err(info->nl_net, RTNLGRP_IPV4_ROUTE, err);
 331 }
 332
 333 /* Return the first fib alias matching TOS with
 334  * priority less than or equal to PRIO.
 335  */
 336 struct fib_alias *fib_find_alias(struct list_head *fah, u8 tos, u32 prio)
 337 {
 338         if (fah) {
 339                 struct fib_alias *fa;
 340                 list_for_each_entry(fa, fah, fa_list) {
 341                         if (fa->fa_tos > tos)
 342                                 continue;
 343                         if (fa->fa_info->fib_priority >= prio ||
 344                             fa->fa_tos < tos)
 345                                 return fa;
 346                 }
 347         }
 348         return NULL;
 349 }
 350
 351 int fib_detect_death(struct fib_info *fi, int order,
 352                      struct fib_info **last_resort, int *last_idx, int dflt)
 353 {
 354         struct neighbour *n;
 355         int state = NUD_NONE;
 356
 357         n = neigh_lookup(&arp_tbl, &fi->fib_nh[0].nh_gw, fi->fib_dev);
 358         if (n) {
 359                 state = n->nud_state;
 360                 neigh_release(n);
 361         }
 362         if (state == NUD_REACHABLE)
 363                 return 0;
 364         if ((state&NUD_VALID) && order != dflt)
 365                 return 0;
 366         if ((state&NUD_VALID) ||
 367             (*last_idx<0 && order > dflt)) {
 368                 *last_resort = fi;
 369                 *last_idx = order;
 370         }
 371         return 1;
 372 }
 373
 374 #ifdef CONFIG_IP_ROUTE_MULTIPATH
 375
 376 static int fib_count_nexthops(struct rtnexthop *rtnh, int remaining)
 377 {
 378         int nhs = 0;
 379
 380         while (rtnh_ok(rtnh, remaining)) {
 381                 nhs++;
 382                 rtnh = rtnh_next(rtnh, &remaining);
 383         }
 384
 385         /* leftover implies invalid nexthop configuration, discard it */
 386         return remaining > 0 ? 0 : nhs;
 387 }
 388
 389 static int fib_get_nhs(struct fib_info *fi, struct rtnexthop *rtnh,
 390                        int remaining, struct fib_config *cfg)
 391 {
 392         change_nexthops(fi) {
 393                 int attrlen;
 394
 395                 if (!rtnh_ok(rtnh, remaining))
 396                         return -EINVAL;
 397
 398                 nh->nh_flags = (cfg->fc_flags & ~0xFF) | rtnh->rtnh_flags;
 399                 nh->nh_oif = rtnh->rtnh_ifindex;
 400                 nh->nh_weight = rtnh->rtnh_hops + 1;
 401
 402                 attrlen = rtnh_attrlen(rtnh);
 403                 if (attrlen > 0) {
 404                         struct nlattr *nla, *attrs = rtnh_attrs(rtnh);
 405
 406                         nla = nla_find(attrs, attrlen, RTA_GATEWAY);
 407                         nh->nh_gw = nla ? nla_get_be32(nla) : 0;
 408 #ifdef CONFIG_NET_CLS_ROUTE
 409                         nla = nla_find(attrs, attrlen, RTA_FLOW);
 410                         nh->nh_tclassid = nla ? nla_get_u32(nla) : 0;
 411 #endif
 412                 }
 413
 414                 rtnh = rtnh_next(rtnh, &remaining);
 415         } endfor_nexthops(fi);
 416
 417         return 0;
 418 }
 419
 420 #endif
 421
 422 int fib_nh_match(struct fib_config *cfg, struct fib_info *fi)
 423 {
 424 #ifdef CONFIG_IP_ROUTE_MULTIPATH
 425         struct rtnexthop *rtnh;
 426         int remaining;
 427 #endif
 428
 429         if (cfg->fc_priority && cfg->fc_priority != fi->fib_priority)
 430                 return 1;
 431
 432         if (cfg->fc_oif || cfg->fc_gw) {
 433                 if ((!cfg->fc_oif || cfg->fc_oif == fi->fib_nh->nh_oif) &&
 434                     (!cfg->fc_gw  || cfg->fc_gw == fi->fib_nh->nh_gw))
 435                         return 0;
 436                 return 1;
 437         }
 438
 439 #ifdef CONFIG_IP_ROUTE_MULTIPATH
 440         if (cfg->fc_mp == NULL)
 441                 return 0;
 442
 443         rtnh = cfg->fc_mp;
 444         remaining = cfg->fc_mp_len;
 445
 446         for_nexthops(fi) {
 447                 int attrlen;
 448
 449                 if (!rtnh_ok(rtnh, remaining))
 450                         return -EINVAL;
 451
 452                 if (rtnh->rtnh_ifindex && rtnh->rtnh_ifindex != nh->nh_oif)
 453                         return 1;
 454
 455                 attrlen = rtnh_attrlen(rtnh);
 456                 if (attrlen < 0) {
 457                         struct nlattr *nla, *attrs = rtnh_attrs(rtnh);
 458
 459                         nla = nla_find(attrs, attrlen, RTA_GATEWAY);
 460                         if (nla && nla_get_be32(nla) != nh->nh_gw)
 461                                 return 1;
 462 #ifdef CONFIG_NET_CLS_ROUTE
 463                         nla = nla_find(attrs, attrlen, RTA_FLOW);
 464                         if (nla && nla_get_u32(nla) != nh->nh_tclassid)
 465                                 return 1;
 466 #endif
 467                 }
 468
 469                 rtnh = rtnh_next(rtnh, &remaining);
 470         } endfor_nexthops(fi);
 471 #endif
 472         return 0;
 473 }
 474
 475
 476 /*
 477    Picture
 478    -------
 479
 480    Semantics of nexthop is very messy by historical reasons.
 481    We have to take into account, that:
 482    a) gateway can be actually local interface address,
 483       so that gatewayed route is direct.
 484    b) gateway must be on-link address, possibly
 485       described not by an ifaddr, but also by a direct route.
 486    c) If both gateway and interface are specified, they should not
 487       contradict.
 488    d) If we use tunnel routes, gateway could be not on-link.
 489
 490    Attempt to reconcile all of these (alas, self-contradictory) conditions
 491    results in pretty ugly and hairy code with obscure logic.
 492
 493    I chose to generalized it instead, so that the size
 494    of code does not increase practically, but it becomes
 495    much more general.
 496    Every prefix is assigned a "scope" value: "host" is local address,
 497    "link" is direct route,
 498    [ ... "site" ... "interior" ... ]
 499    and "universe" is true gateway route with global meaning.
 500
 501    Every prefix refers to a set of "nexthop"s (gw, oif),
 502    where gw must have narrower scope. This recursion stops
 503    when gw has LOCAL scope or if "nexthop" is declared ONLINK,
 504    which means that gw is forced to be on link.
 505
 506    Code is still hairy, but now it is apparently logically
 507    consistent and very flexible. F.e. as by-product it allows
 508    to co-exists in peace independent exterior and interior
 509    routing processes.
 510
 511    Normally it looks as following.
 512
 513    {universe prefix}  -> (gw, oif) [scope link]
 514                           |
 515                           |-> {link prefix} -> (gw, oif) [scope local]
 516                                                 |
 517                                                 |-> {local prefix} (terminal node)
 518  */
 519
 520 static int fib_check_nh(struct fib_config *cfg, struct fib_info *fi,
 521                         struct fib_nh *nh)
 522 {
 523         int err;
 524         struct net *net;
 525
 526         net = cfg->fc_nlinfo.nl_net;
 527         if (nh->nh_gw) {
 528                 struct fib_result res;
 529
 530 #ifdef CONFIG_IP_ROUTE_PERVASIVE
 531                 if (nh->nh_flags&RTNH_F_PERVASIVE)
 532                         return 0;
 533 #endif
 534                 if (nh->nh_flags&RTNH_F_ONLINK) {
 535                         struct net_device *dev;
 536
 537                         if (cfg->fc_scope >= RT_SCOPE_LINK)
 538                                 return -EINVAL;
 539                         if (inet_addr_type(net, nh->nh_gw) != RTN_UNICAST)
 540                                 return -EINVAL;
 541                         if ((dev = __dev_get_by_index(net, nh->nh_oif)) == NULL)
 542                                 return -ENODEV;
 543                         if (!(dev->flags&IFF_UP))
 544                                 return -ENETDOWN;
 545                         nh->nh_dev = dev;
 546                         dev_hold(dev);
 547                         nh->nh_scope = RT_SCOPE_LINK;
 548                         return 0;
 549                 }
 550                 {
 551                         struct flowi fl = {
 552                                 .nl_u = {
 553                                         .ip4_u = {
 554                                                 .daddr = nh->nh_gw,
 555                                                 .scope = cfg->fc_scope + 1,
 556                                         },
 557                                 },
 558                                 .oif = nh->nh_oif,
 559                         };
 560
 561                         /* It is not necessary, but requires a bit of thinking */
 562                         if (fl.fl4_scope < RT_SCOPE_LINK)
 563                                 fl.fl4_scope = RT_SCOPE_LINK;
 564                         if ((err = fib_lookup(net, &fl, &res)) != 0)
 565                                 return err;
 566                 }
 567                 err = -EINVAL;
 568                 if (res.type != RTN_UNICAST && res.type != RTN_LOCAL)
 569                         goto out;
 570                 nh->nh_scope = res.scope;
 571                 nh->nh_oif = FIB_RES_OIF(res);
 572                 if ((nh->nh_dev = FIB_RES_DEV(res)) == NULL)
 573                         goto out;
 574                 dev_hold(nh->nh_dev);
 575                 err = -ENETDOWN;
 576                 if (!(nh->nh_dev->flags & IFF_UP))
 577                         goto out;
 578                 err = 0;
 579 out:
 580                 fib_res_put(&res);
 581                 return err;
 582         } else {
 583                 struct in_device *in_dev;
 584
 585                 if (nh->nh_flags&(RTNH_F_PERVASIVE|RTNH_F_ONLINK))
 586                         return -EINVAL;
 587
 588                 in_dev = inetdev_by_index(net, nh->nh_oif);
 589                 if (in_dev == NULL)
 590                         return -ENODEV;
 591                 if (!(in_dev->dev->flags&IFF_UP)) {
 592                         in_dev_put(in_dev);
 593                         return -ENETDOWN;
 594                 }
 595                 nh->nh_dev = in_dev->dev;
 596                 dev_hold(nh->nh_dev);
 597                 nh->nh_scope = RT_SCOPE_HOST;
 598                 in_dev_put(in_dev);
 599         }
 600         return 0;
 601 }
 602
 603 static inline unsigned int fib_laddr_hashfn(__be32 val)
 604 {
 605         unsigned int mask = (fib_hash_size - 1);
 606
 607         return ((__force u32)val ^ ((__force u32)val >> 7) ^ ((__force u32)val >> 14)) & mask;
 608 }
 609
 610 static struct hlist_head *fib_hash_alloc(int bytes)
 611 {
 612         if (bytes <= PAGE_SIZE)
 613                 return kzalloc(bytes, GFP_KERNEL);
 614         else
 615                 return (struct hlist_head *)
 616                         __get_free_pages(GFP_KERNEL | __GFP_ZERO, get_order(bytes));
 617 }
 618
 619 static void fib_hash_free(struct hlist_head *hash, int bytes)
 620 {
 621         if (!hash)
 622                 return;
 623
 624         if (bytes <= PAGE_SIZE)
 625                 kfree(hash);
 626         else
 627                 free_pages((unsigned long) hash, get_order(bytes));
 628 }
 629
 630 static void fib_hash_move(struct hlist_head *new_info_hash,
 631                           struct hlist_head *new_laddrhash,
 632                           unsigned int new_size)
 633 {
 634         struct hlist_head *old_info_hash, *old_laddrhash;
 635         unsigned int old_size = fib_hash_size;
 636         unsigned int i, bytes;
 637
 638         spin_lock_bh(&fib_info_lock);
 639         old_info_hash = fib_info_hash;
 640         old_laddrhash = fib_info_laddrhash;
 641         fib_hash_size = new_size;
 642
 643         for (i = 0; i < old_size; i++) {
 644                 struct hlist_head *head = &fib_info_hash[i];
 645                 struct hlist_node *node, *n;
 646                 struct fib_info *fi;
 647
 648                 hlist_for_each_entry_safe(fi, node, n, head, fib_hash) {
 649                         struct hlist_head *dest;
 650                         unsigned int new_hash;
 651
 652                         hlist_del(&fi->fib_hash);
 653
 654                         new_hash = fib_info_hashfn(fi);
 655                         dest = &new_info_hash[new_hash];
 656                         hlist_add_head(&fi->fib_hash, dest);
 657                 }
 658         }
 659         fib_info_hash = new_info_hash;
 660
 661         for (i = 0; i < old_size; i++) {
 662                 struct hlist_head *lhead = &fib_info_laddrhash[i];
 663                 struct hlist_node *node, *n;
 664                 struct fib_info *fi;
 665
 666                 hlist_for_each_entry_safe(fi, node, n, lhead, fib_lhash) {
 667                         struct hlist_head *ldest;
 668                         unsigned int new_hash;
 669
 670                         hlist_del(&fi->fib_lhash);
 671
 672                         new_hash = fib_laddr_hashfn(fi->fib_prefsrc);
 673                         ldest = &new_laddrhash[new_hash];
 674                         hlist_add_head(&fi->fib_lhash, ldest);
 675                 }
 676         }
 677         fib_info_laddrhash = new_laddrhash;
 678
 679         spin_unlock_bh(&fib_info_lock);
 680
 681         bytes = old_size * sizeof(struct hlist_head *);
 682         fib_hash_free(old_info_hash, bytes);
 683         fib_hash_free(old_laddrhash, bytes);
 684 }
 685
 686 struct fib_info *fib_create_info(struct fib_config *cfg)
 687 {
 688         int err;
 689         struct fib_info *fi = NULL;
 690         struct fib_info *ofi;
 691         int nhs = 1;
 692         struct net *net = cfg->fc_nlinfo.nl_net;
 693
 694         /* Fast check to catch the most weird cases */
 695         if (fib_props[cfg->fc_type].scope > cfg->fc_scope)
 696                 goto err_inval;
 697
 698 #ifdef CONFIG_IP_ROUTE_MULTIPATH
 699         if (cfg->fc_mp) {
 700                 nhs = fib_count_nexthops(cfg->fc_mp, cfg->fc_mp_len);
 701                 if (nhs == 0)
 702                         goto err_inval;
 703         }
 704 #endif
 705
 706         err = -ENOBUFS;
 707         if (fib_info_cnt >= fib_hash_size) {
 708                 unsigned int new_size = fib_hash_size << 1;
 709                 struct hlist_head *new_info_hash;
 710                 struct hlist_head *new_laddrhash;
 711                 unsigned int bytes;
 712
 713                 if (!new_size)
 714                         new_size = 1;
 715                 bytes = new_size * sizeof(struct hlist_head *);
 716                 new_info_hash = fib_hash_alloc(bytes);
 717                 new_laddrhash = fib_hash_alloc(bytes);
 718                 if (!new_info_hash || !new_laddrhash) {
 719                         fib_hash_free(new_info_hash, bytes);
 720                         fib_hash_free(new_laddrhash, bytes);
 721                 } else
 722                         fib_hash_move(new_info_hash, new_laddrhash, new_size);
 723
 724                 if (!fib_hash_size)
 725                         goto failure;
 726         }
 727
 728         fi = kzalloc(sizeof(*fi)+nhs*sizeof(struct fib_nh), GFP_KERNEL);
 729         if (fi == NULL)
 730                 goto failure;
 731         fib_info_cnt++;
 732
 733         fi->fib_net = hold_net(net);
 734         fi->fib_protocol = cfg->fc_protocol;
 735         fi->fib_flags = cfg->fc_flags;
 736         fi->fib_priority = cfg->fc_priority;
 737         fi->fib_prefsrc = cfg->fc_prefsrc;
 738
 739         fi->fib_nhs = nhs;
 740         change_nexthops(fi) {
 741                 nh->nh_parent = fi;
 742         } endfor_nexthops(fi)
 743
 744         if (cfg->fc_mx) {
 745                 struct nlattr *nla;
 746                 int remaining;
 747
 748                 nla_for_each_attr(nla, cfg->fc_mx, cfg->fc_mx_len, remaining) {
 749                         int type = nla_type(nla);
 750
 751                         if (type) {
 752                                 if (type > RTAX_MAX)
 753                                         goto err_inval;
 754                                 fi->fib_metrics[type - 1] = nla_get_u32(nla);
 755                         }
 756                 }
 757         }
 758
 759         if (cfg->fc_mp) {
 760 #ifdef CONFIG_IP_ROUTE_MULTIPATH
 761                 err = fib_get_nhs(fi, cfg->fc_mp, cfg->fc_mp_len, cfg);
 762                 if (err != 0)
 763                         goto failure;
 764                 if (cfg->fc_oif && fi->fib_nh->nh_oif != cfg->fc_oif)
 765                         goto err_inval;
 766                 if (cfg->fc_gw && fi->fib_nh->nh_gw != cfg->fc_gw)
 767                         goto err_inval;
 768 #ifdef CONFIG_NET_CLS_ROUTE
 769                 if (cfg->fc_flow && fi->fib_nh->nh_tclassid != cfg->fc_flow)
 770                         goto err_inval;
 771 #endif
 772 #else
 773                 goto err_inval;
 774 #endif
 775         } else {
 776                 struct fib_nh *nh = fi->fib_nh;
 777
 778                 nh->nh_oif = cfg->fc_oif;
 779                 nh->nh_gw = cfg->fc_gw;
 780                 nh->nh_flags = cfg->fc_flags;
 781 #ifdef CONFIG_NET_CLS_ROUTE
 782                 nh->nh_tclassid = cfg->fc_flow;
 783 #endif
 784 #ifdef CONFIG_IP_ROUTE_MULTIPATH
 785                 nh->nh_weight = 1;
 786 #endif
 787         }
 788
 789         if (fib_props[cfg->fc_type].error) {
 790                 if (cfg->fc_gw || cfg->fc_oif || cfg->fc_mp)
 791                         goto err_inval;
 792                 goto link_it;
 793         }
 794
 795         if (cfg->fc_scope > RT_SCOPE_HOST)
 796                 goto err_inval;
 797
 798         if (cfg->fc_scope == RT_SCOPE_HOST) {
 799                 struct fib_nh *nh = fi->fib_nh;
 800
 801                 /* Local address is added. */
 802                 if (nhs != 1 || nh->nh_gw)
 803                         goto err_inval;
 804                 nh->nh_scope = RT_SCOPE_NOWHERE;
 805                 nh->nh_dev = dev_get_by_index(net, fi->fib_nh->nh_oif);
 806                 err = -ENODEV;
 807                 if (nh->nh_dev == NULL)
 808                         goto failure;
 809         } else {
 810                 change_nexthops(fi) {
 811                         if ((err = fib_check_nh(cfg, fi, nh)) != 0)
 812                                 goto failure;
 813                 } endfor_nexthops(fi)
 814         }
 815
 816         if (fi->fib_prefsrc) {
 817                 if (cfg->fc_type != RTN_LOCAL || !cfg->fc_dst ||
 818                     fi->fib_prefsrc != cfg->fc_dst)
 819                         if (inet_addr_type(net, fi->fib_prefsrc) != RTN_LOCAL)
 820                                 goto err_inval;
 821         }
 822
 823 link_it:
 824         if ((ofi = fib_find_info(fi)) != NULL) {
 825                 fi->fib_dead = 1;
 826                 free_fib_info(fi);
 827                 ofi->fib_treeref++;
 828                 return ofi;
 829         }
 830
 831         fi->fib_treeref++;
 832         atomic_inc(&fi->fib_clntref);
 833         spin_lock_bh(&fib_info_lock);
 834         hlist_add_head(&fi->fib_hash,
 835                        &fib_info_hash[fib_info_hashfn(fi)]);
 836         if (fi->fib_prefsrc) {
 837                 struct hlist_head *head;
 838
 839                 head = &fib_info_laddrhash[fib_laddr_hashfn(fi->fib_prefsrc)];
 840                 hlist_add_head(&fi->fib_lhash, head);
 841         }
 842         change_nexthops(fi) {
 843                 struct hlist_head *head;
 844                 unsigned int hash;
 845
 846                 if (!nh->nh_dev)
 847                         continue;
 848                 hash = fib_devindex_hashfn(nh->nh_dev->ifindex);
 849                 head = &fib_info_devhash[hash];
 850                 hlist_add_head(&nh->nh_hash, head);
 851         } endfor_nexthops(fi)
 852         spin_unlock_bh(&fib_info_lock);
 853         return fi;
 854
 855 err_inval:
 856         err = -EINVAL;
 857
 858 failure:
 859         if (fi) {
 860                 fi->fib_dead = 1;
 861                 free_fib_info(fi);
 862         }
 863
 864         return ERR_PTR(err);
 865 }
 866
 867 /* Note! fib_semantic_match intentionally uses  RCU list functions. */
 868 int fib_semantic_match(struct list_head *head, const struct flowi *flp,
 869                        struct fib_result *res, int prefixlen)
 870 {
 871         struct fib_alias *fa;
 872         int nh_sel = 0;
 873
 874         list_for_each_entry_rcu(fa, head, fa_list) {
 875                 int err;
 876
 877                 if (fa->fa_tos &&
 878                     fa->fa_tos != flp->fl4_tos)
 879                         continue;
 880
 881                 if (fa->fa_scope < flp->fl4_scope)
 882                         continue;
 883
 884                 fa->fa_state |= FA_S_ACCESSED;
 885
 886                 err = fib_props[fa->fa_type].error;
 887                 if (err == 0) {
 888                         struct fib_info *fi = fa->fa_info;
 889
 890                         if (fi->fib_flags & RTNH_F_DEAD)
 891                                 continue;
 892
 893                         switch (fa->fa_type) {
 894                         case RTN_UNICAST:
 895                         case RTN_LOCAL:
 896                         case RTN_BROADCAST:
 897                         case RTN_ANYCAST:
 898                         case RTN_MULTICAST:
 899                                 for_nexthops(fi) {
 900                                         if (nh->nh_flags&RTNH_F_DEAD)
 901                                                 continue;
 902                                         if (!flp->oif || flp->oif == nh->nh_oif)
 903                                                 break;
 904                                 }
 905 #ifdef CONFIG_IP_ROUTE_MULTIPATH
 906                                 if (nhsel < fi->fib_nhs) {
 907                                         nh_sel = nhsel;
 908                                         goto out_fill_res;
 909                                 }
 910 #else
 911                                 if (nhsel < 1) {
 912                                         goto out_fill_res;
 913                                 }
 914 #endif
 915                                 endfor_nexthops(fi);
 916                                 continue;
 917
 918                         default:
 919                                 printk(KERN_WARNING "fib_semantic_match bad type %#x\n",
 920                                         fa->fa_type);
 921                                 return -EINVAL;
 922                         }
 923                 }
 924                 return err;
 925         }
 926         return 1;
 927
 928 out_fill_res:
 929         res->prefixlen = prefixlen;
 930         res->nh_sel = nh_sel;
 931         res->type = fa->fa_type;
 932         res->scope = fa->fa_scope;
 933         res->fi = fa->fa_info;
 934         atomic_inc(&res->fi->fib_clntref);
 935         return 0;
 936 }
 937
 938 /* Find appropriate source address to this destination */
 939
 940 __be32 __fib_res_prefsrc(struct fib_result *res)
 941 {
 942         return inet_select_addr(FIB_RES_DEV(*res), FIB_RES_GW(*res), res->scope);
 943 }
 944
 945 int fib_dump_info(struct sk_buff *skb, u32 pid, u32 seq, int event,
 946                   u32 tb_id, u8 type, u8 scope, __be32 dst, int dst_len, u8 tos,
 947                   struct fib_info *fi, unsigned int flags)
 948 {
 949         struct nlmsghdr *nlh;
 950         struct rtmsg *rtm;
 951
 952         nlh = nlmsg_put(skb, pid, seq, event, sizeof(*rtm), flags);
 953         if (nlh == NULL)
 954                 return -EMSGSIZE;
 955
 956         rtm = nlmsg_data(nlh);
 957         rtm->rtm_family = AF_INET;
 958         rtm->rtm_dst_len = dst_len;
 959         rtm->rtm_src_len = 0;
 960         rtm->rtm_tos = tos;
 961         if (tb_id < 256)
 962                 rtm->rtm_table = tb_id;
 963         else
 964                 rtm->rtm_table = RT_TABLE_COMPAT;
 965         NLA_PUT_U32(skb, RTA_TABLE, tb_id);
 966         rtm->rtm_type = type;
 967         rtm->rtm_flags = fi->fib_flags;
 968         rtm->rtm_scope = scope;
 969         rtm->rtm_protocol = fi->fib_protocol;
 970
 971         if (rtm->rtm_dst_len)
 972                 NLA_PUT_BE32(skb, RTA_DST, dst);
 973
 974         if (fi->fib_priority)
 975                 NLA_PUT_U32(skb, RTA_PRIORITY, fi->fib_priority);
 976
 977         if (rtnetlink_put_metrics(skb, fi->fib_metrics) < 0)
 978                 goto nla_put_failure;
 979
 980         if (fi->fib_prefsrc)
 981                 NLA_PUT_BE32(skb, RTA_PREFSRC, fi->fib_prefsrc);
 982
 983         if (fi->fib_nhs == 1) {
 984                 if (fi->fib_nh->nh_gw)
 985                         NLA_PUT_BE32(skb, RTA_GATEWAY, fi->fib_nh->nh_gw);
 986
 987                 if (fi->fib_nh->nh_oif)
 988                         NLA_PUT_U32(skb, RTA_OIF, fi->fib_nh->nh_oif);
 989 #ifdef CONFIG_NET_CLS_ROUTE
 990                 if (fi->fib_nh[0].nh_tclassid)
 991                         NLA_PUT_U32(skb, RTA_FLOW, fi->fib_nh[0].nh_tclassid);
 992 #endif
 993         }
 994 #ifdef CONFIG_IP_ROUTE_MULTIPATH
 995         if (fi->fib_nhs > 1) {
 996                 struct rtnexthop *rtnh;
 997                 struct nlattr *mp;
 998
 999                 mp = nla_nest_start(skb, RTA_MULTIPATH);
1000                 if (mp == NULL)
1001                         goto nla_put_failure;
1002
1003                 for_nexthops(fi) {
1004                         rtnh = nla_reserve_nohdr(skb, sizeof(*rtnh));
1005                         if (rtnh == NULL)
1006                                 goto nla_put_failure;
1007
1008                         rtnh->rtnh_flags = nh->nh_flags & 0xFF;
1009                         rtnh->rtnh_hops = nh->nh_weight - 1;
1010                         rtnh->rtnh_ifindex = nh->nh_oif;
1011
1012                         if (nh->nh_gw)
1013                                 NLA_PUT_BE32(skb, RTA_GATEWAY, nh->nh_gw);
1014 #ifdef CONFIG_NET_CLS_ROUTE
1015                         if (nh->nh_tclassid)
1016                                 NLA_PUT_U32(skb, RTA_FLOW, nh->nh_tclassid);
1017 #endif
1018                         /* length of rtnetlink header + attributes */
1019                         rtnh->rtnh_len = nlmsg_get_pos(skb) - (void *) rtnh;
1020                 } endfor_nexthops(fi);
1021
1022                 nla_nest_end(skb, mp);
1023         }
1024 #endif
1025         return nlmsg_end(skb, nlh);
1026
1027 nla_put_failure:
1028         nlmsg_cancel(skb, nlh);
1029         return -EMSGSIZE;
1030 }
1031
1032 /*
1033    Update FIB if:
1034    - local address disappeared -> we must delete all the entries
1035      referring to it.
1036    - device went down -> we must shutdown all nexthops going via it.
1037  */
1038 int fib_sync_down_addr(struct net *net, __be32 local)
1039 {
1040         int ret = 0;
1041         unsigned int hash = fib_laddr_hashfn(local);
1042         struct hlist_head *head = &fib_info_laddrhash[hash];
1043         struct hlist_node *node;
1044         struct fib_info *fi;
1045
1046         if (fib_info_laddrhash == NULL || local == 0)
1047                 return 0;
1048
1049         hlist_for_each_entry(fi, node, head, fib_lhash) {
1050                 if (fi->fib_net != net)
1051                         continue;
1052                 if (fi->fib_prefsrc == local) {
1053                         fi->fib_flags |= RTNH_F_DEAD;
1054                         ret++;
1055                 }
1056         }
1057         return ret;
1058 }
1059
1060 int fib_sync_down_dev(struct net_device *dev, int force)
1061 {
1062         int ret = 0;
1063         int scope = RT_SCOPE_NOWHERE;
1064         struct fib_info *prev_fi = NULL;
1065         unsigned int hash = fib_devindex_hashfn(dev->ifindex);
1066         struct hlist_head *head = &fib_info_devhash[hash];
1067         struct hlist_node *node;
1068         struct fib_nh *nh;
1069
1070         if (force)
1071                 scope = -1;
1072
1073         hlist_for_each_entry(nh, node, head, nh_hash) {
1074                 struct fib_info *fi = nh->nh_parent;
1075                 int dead;
1076
1077                 BUG_ON(!fi->fib_nhs);
1078                 if (nh->nh_dev != dev || fi == prev_fi)
1079                         continue;
1080                 prev_fi = fi;
1081                 dead = 0;
1082                 change_nexthops(fi) {
1083                         if (nh->nh_flags&RTNH_F_DEAD)
1084                                 dead++;
1085                         else if (nh->nh_dev == dev &&
1086                                         nh->nh_scope != scope) {
1087                                 nh->nh_flags |= RTNH_F_DEAD;
1088 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1089                                 spin_lock_bh(&fib_multipath_lock);
1090                                 fi->fib_power -= nh->nh_power;
1091                                 nh->nh_power = 0;
1092                                 spin_unlock_bh(&fib_multipath_lock);
1093 #endif
1094                                 dead++;
1095                         }
1096 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1097                         if (force > 1 && nh->nh_dev == dev) {
1098                                 dead = fi->fib_nhs;
1099                                 break;
1100                         }
1101 #endif
1102                 } endfor_nexthops(fi)
1103                 if (dead == fi->fib_nhs) {
1104                         fi->fib_flags |= RTNH_F_DEAD;
1105                         ret++;
1106                 }
1107         }
1108
1109         return ret;
1110 }
1111
1112 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1113
1114 /*
1115    Dead device goes up. We wake up dead nexthops.
1116    It takes sense only on multipath routes.
1117  */
1118
1119 int fib_sync_up(struct net_device *dev)
1120 {
1121         struct fib_info *prev_fi;
1122         unsigned int hash;
1123         struct hlist_head *head;
1124         struct hlist_node *node;
1125         struct fib_nh *nh;
1126         int ret;
1127
1128         if (!(dev->flags&IFF_UP))
1129                 return 0;
1130
1131         prev_fi = NULL;
1132         hash = fib_devindex_hashfn(dev->ifindex);
1133         head = &fib_info_devhash[hash];
1134         ret = 0;
1135
1136         hlist_for_each_entry(nh, node, head, nh_hash) {
1137                 struct fib_info *fi = nh->nh_parent;
1138                 int alive;
1139
1140                 BUG_ON(!fi->fib_nhs);
1141                 if (nh->nh_dev != dev || fi == prev_fi)
1142                         continue;
1143
1144                 prev_fi = fi;
1145                 alive = 0;
1146                 change_nexthops(fi) {
1147                         if (!(nh->nh_flags&RTNH_F_DEAD)) {
1148                                 alive++;
1149                                 continue;
1150                         }
1151                         if (nh->nh_dev == NULL || !(nh->nh_dev->flags&IFF_UP))
1152                                 continue;
1153                         if (nh->nh_dev != dev || !__in_dev_get_rtnl(dev))
1154                                 continue;
1155                         alive++;
1156                         spin_lock_bh(&fib_multipath_lock);
1157                         nh->nh_power = 0;
1158                         nh->nh_flags &= ~RTNH_F_DEAD;
1159                         spin_unlock_bh(&fib_multipath_lock);
1160                 } endfor_nexthops(fi)
1161
1162                 if (alive > 0) {
1163                         fi->fib_flags &= ~RTNH_F_DEAD;
1164                         ret++;
1165                 }
1166         }
1167
1168         return ret;
1169 }
1170
1171 /*
1172    The algorithm is suboptimal, but it provides really
1173    fair weighted route distribution.
1174  */
1175
1176 void fib_select_multipath(const struct flowi *flp, struct fib_result *res)
1177 {
1178         struct fib_info *fi = res->fi;
1179         int w;
1180
1181         spin_lock_bh(&fib_multipath_lock);
1182         if (fi->fib_power <= 0) {
1183                 int power = 0;
1184                 change_nexthops(fi) {
1185                         if (!(nh->nh_flags&RTNH_F_DEAD)) {
1186                                 power += nh->nh_weight;
1187                                 nh->nh_power = nh->nh_weight;
1188                         }
1189                 } endfor_nexthops(fi);
1190                 fi->fib_power = power;
1191                 if (power <= 0) {
1192                         spin_unlock_bh(&fib_multipath_lock);
1193                         /* Race condition: route has just become dead. */
1194                         res->nh_sel = 0;
1195                         return;
1196                 }
1197         }
1198
1199
1200         /* w should be random number [0..fi->fib_power-1],
1201            it is pretty bad approximation.
1202          */
1203
1204         w = jiffies % fi->fib_power;
1205
1206         change_nexthops(fi) {
1207                 if (!(nh->nh_flags&RTNH_F_DEAD) && nh->nh_power) {
1208                         if ((w -= nh->nh_power) <= 0) {
1209                                 nh->nh_power--;
1210                                 fi->fib_power--;
1211                                 res->nh_sel = nhsel;
1212                                 spin_unlock_bh(&fib_multipath_lock);
1213                                 return;
1214                         }
1215                 }
1216         } endfor_nexthops(fi);
1217
1218         /* Race condition: route has just become dead. */
1219         res->nh_sel = 0;
1220         spin_unlock_bh(&fib_multipath_lock);
1221 }
1222 #endif