net/ipv4/fib_semantics.c

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