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fib_semantics.c
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1 /*
2  * INET An implementation of the TCP/IP protocol suite for the LINUX
3  * operating system. INET is implemented using the BSD Socket
4  * interface as the means of communication with the user level.
5  *
6  * IPv4 Forwarding Information Base: semantics.
7  *
8  * Authors: Alexey Kuznetsov, <[email protected]>
9  *
10  * This program is free software; you can redistribute it and/or
11  * modify it under the terms of the GNU General Public License
12  * as published by the Free Software Foundation; either version
13  * 2 of the License, or (at your option) any later version.
14  */
15 
16 #include <asm/uaccess.h>
17 #include <linux/bitops.h>
18 #include <linux/types.h>
19 #include <linux/kernel.h>
20 #include <linux/jiffies.h>
21 #include <linux/mm.h>
22 #include <linux/string.h>
23 #include <linux/socket.h>
24 #include <linux/sockios.h>
25 #include <linux/errno.h>
26 #include <linux/in.h>
27 #include <linux/inet.h>
28 #include <linux/inetdevice.h>
29 #include <linux/netdevice.h>
30 #include <linux/if_arp.h>
31 #include <linux/proc_fs.h>
32 #include <linux/skbuff.h>
33 #include <linux/init.h>
34 #include <linux/slab.h>
35 
36 #include <net/arp.h>
37 #include <net/ip.h>
38 #include <net/protocol.h>
39 #include <net/route.h>
40 #include <net/tcp.h>
41 #include <net/sock.h>
42 #include <net/ip_fib.h>
43 #include <net/netlink.h>
44 #include <net/nexthop.h>
45 
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_info_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) { \
63  int nhsel; const struct fib_nh *nh; \
64  for (nhsel = 0, nh = (fi)->fib_nh; \
65  nhsel < (fi)->fib_nhs; \
66  nh++, nhsel++)
67 
68 #define change_nexthops(fi) { \
69  int nhsel; struct fib_nh *nexthop_nh; \
70  for (nhsel = 0, nexthop_nh = (struct fib_nh *)((fi)->fib_nh); \
71  nhsel < (fi)->fib_nhs; \
72  nexthop_nh++, nhsel++)
73 
74 #else /* CONFIG_IP_ROUTE_MULTIPATH */
75 
76 /* Hope, that gcc will optimize it to get rid of dummy loop */
77 
78 #define for_nexthops(fi) { \
79  int nhsel; const struct fib_nh *nh = (fi)->fib_nh; \
80  for (nhsel = 0; nhsel < 1; nhsel++)
81 
82 #define change_nexthops(fi) { \
83  int nhsel; \
84  struct fib_nh *nexthop_nh = (struct fib_nh *)((fi)->fib_nh); \
85  for (nhsel = 0; nhsel < 1; nhsel++)
86 
87 #endif /* CONFIG_IP_ROUTE_MULTIPATH */
88 
89 #define endfor_nexthops(fi) }
90 
91 
92 const struct fib_prop fib_props[RTN_MAX + 1] = {
93  [RTN_UNSPEC] = {
94  .error = 0,
95  .scope = RT_SCOPE_NOWHERE,
96  },
97  [RTN_UNICAST] = {
98  .error = 0,
99  .scope = RT_SCOPE_UNIVERSE,
100  },
101  [RTN_LOCAL] = {
102  .error = 0,
103  .scope = RT_SCOPE_HOST,
104  },
105  [RTN_BROADCAST] = {
106  .error = 0,
107  .scope = RT_SCOPE_LINK,
108  },
109  [RTN_ANYCAST] = {
110  .error = 0,
111  .scope = RT_SCOPE_LINK,
112  },
113  [RTN_MULTICAST] = {
114  .error = 0,
115  .scope = RT_SCOPE_UNIVERSE,
116  },
117  [RTN_BLACKHOLE] = {
118  .error = -EINVAL,
119  .scope = RT_SCOPE_UNIVERSE,
120  },
121  [RTN_UNREACHABLE] = {
122  .error = -EHOSTUNREACH,
123  .scope = RT_SCOPE_UNIVERSE,
124  },
125  [RTN_PROHIBIT] = {
126  .error = -EACCES,
127  .scope = RT_SCOPE_UNIVERSE,
128  },
129  [RTN_THROW] = {
130  .error = -EAGAIN,
131  .scope = RT_SCOPE_UNIVERSE,
132  },
133  [RTN_NAT] = {
134  .error = -EINVAL,
135  .scope = RT_SCOPE_NOWHERE,
136  },
137  [RTN_XRESOLVE] = {
138  .error = -EINVAL,
139  .scope = RT_SCOPE_NOWHERE,
140  },
141 };
142 
143 static void rt_fibinfo_free(struct rtable __rcu **rtp)
144 {
145  struct rtable *rt = rcu_dereference_protected(*rtp, 1);
146 
147  if (!rt)
148  return;
149 
150  /* Not even needed : RCU_INIT_POINTER(*rtp, NULL);
151  * because we waited an RCU grace period before calling
152  * free_fib_info_rcu()
153  */
154 
155  dst_free(&rt->dst);
156 }
157 
158 static void free_nh_exceptions(struct fib_nh *nh)
159 {
160  struct fnhe_hash_bucket *hash = nh->nh_exceptions;
161  int i;
162 
163  for (i = 0; i < FNHE_HASH_SIZE; i++) {
164  struct fib_nh_exception *fnhe;
165 
166  fnhe = rcu_dereference_protected(hash[i].chain, 1);
167  while (fnhe) {
168  struct fib_nh_exception *next;
169 
170  next = rcu_dereference_protected(fnhe->fnhe_next, 1);
171 
172  rt_fibinfo_free(&fnhe->fnhe_rth);
173 
174  kfree(fnhe);
175 
176  fnhe = next;
177  }
178  }
179  kfree(hash);
180 }
181 
182 static void rt_fibinfo_free_cpus(struct rtable __rcu * __percpu *rtp)
183 {
184  int cpu;
185 
186  if (!rtp)
187  return;
188 
189  for_each_possible_cpu(cpu) {
190  struct rtable *rt;
191 
192  rt = rcu_dereference_protected(*per_cpu_ptr(rtp, cpu), 1);
193  if (rt)
194  dst_free(&rt->dst);
195  }
196  free_percpu(rtp);
197 }
198 
199 /* Release a nexthop info record */
200 static void free_fib_info_rcu(struct rcu_head *head)
201 {
202  struct fib_info *fi = container_of(head, struct fib_info, rcu);
203 
204  change_nexthops(fi) {
205  if (nexthop_nh->nh_dev)
206  dev_put(nexthop_nh->nh_dev);
207  if (nexthop_nh->nh_exceptions)
208  free_nh_exceptions(nexthop_nh);
209  rt_fibinfo_free_cpus(nexthop_nh->nh_pcpu_rth_output);
210  rt_fibinfo_free(&nexthop_nh->nh_rth_input);
211  } endfor_nexthops(fi);
212 
213  release_net(fi->fib_net);
214  if (fi->fib_metrics != (u32 *) dst_default_metrics)
215  kfree(fi->fib_metrics);
216  kfree(fi);
217 }
218 
219 void free_fib_info(struct fib_info *fi)
220 {
221  if (fi->fib_dead == 0) {
222  pr_warn("Freeing alive fib_info %p\n", fi);
223  return;
224  }
225  fib_info_cnt--;
226 #ifdef CONFIG_IP_ROUTE_CLASSID
227  change_nexthops(fi) {
228  if (nexthop_nh->nh_tclassid)
229  fi->fib_net->ipv4.fib_num_tclassid_users--;
230  } endfor_nexthops(fi);
231 #endif
232  call_rcu(&fi->rcu, free_fib_info_rcu);
233 }
234 
235 void fib_release_info(struct fib_info *fi)
236 {
237  spin_lock_bh(&fib_info_lock);
238  if (fi && --fi->fib_treeref == 0) {
239  hlist_del(&fi->fib_hash);
240  if (fi->fib_prefsrc)
241  hlist_del(&fi->fib_lhash);
242  change_nexthops(fi) {
243  if (!nexthop_nh->nh_dev)
244  continue;
245  hlist_del(&nexthop_nh->nh_hash);
246  } endfor_nexthops(fi)
247  fi->fib_dead = 1;
248  fib_info_put(fi);
249  }
250  spin_unlock_bh(&fib_info_lock);
251 }
252 
253 static inline int nh_comp(const struct fib_info *fi, const struct fib_info *ofi)
254 {
255  const struct fib_nh *onh = ofi->fib_nh;
256 
257  for_nexthops(fi) {
258  if (nh->nh_oif != onh->nh_oif ||
259  nh->nh_gw != onh->nh_gw ||
260  nh->nh_scope != onh->nh_scope ||
261 #ifdef CONFIG_IP_ROUTE_MULTIPATH
262  nh->nh_weight != onh->nh_weight ||
263 #endif
264 #ifdef CONFIG_IP_ROUTE_CLASSID
265  nh->nh_tclassid != onh->nh_tclassid ||
266 #endif
267  ((nh->nh_flags ^ onh->nh_flags) & ~RTNH_F_DEAD))
268  return -1;
269  onh++;
270  } endfor_nexthops(fi);
271  return 0;
272 }
273 
274 static inline unsigned int fib_devindex_hashfn(unsigned int val)
275 {
276  unsigned int mask = DEVINDEX_HASHSIZE - 1;
277 
278  return (val ^
279  (val >> DEVINDEX_HASHBITS) ^
280  (val >> (DEVINDEX_HASHBITS * 2))) & mask;
281 }
282 
283 static inline unsigned int fib_info_hashfn(const struct fib_info *fi)
284 {
285  unsigned int mask = (fib_info_hash_size - 1);
286  unsigned int val = fi->fib_nhs;
287 
288  val ^= (fi->fib_protocol << 8) | fi->fib_scope;
289  val ^= (__force u32)fi->fib_prefsrc;
290  val ^= fi->fib_priority;
291  for_nexthops(fi) {
292  val ^= fib_devindex_hashfn(nh->nh_oif);
293  } endfor_nexthops(fi)
294 
295  return (val ^ (val >> 7) ^ (val >> 12)) & mask;
296 }
297 
298 static struct fib_info *fib_find_info(const struct fib_info *nfi)
299 {
300  struct hlist_head *head;
301  struct hlist_node *node;
302  struct fib_info *fi;
303  unsigned int hash;
304 
305  hash = fib_info_hashfn(nfi);
306  head = &fib_info_hash[hash];
307 
308  hlist_for_each_entry(fi, node, head, fib_hash) {
309  if (!net_eq(fi->fib_net, nfi->fib_net))
310  continue;
311  if (fi->fib_nhs != nfi->fib_nhs)
312  continue;
313  if (nfi->fib_protocol == fi->fib_protocol &&
314  nfi->fib_scope == fi->fib_scope &&
315  nfi->fib_prefsrc == fi->fib_prefsrc &&
316  nfi->fib_priority == fi->fib_priority &&
317  nfi->fib_type == fi->fib_type &&
318  memcmp(nfi->fib_metrics, fi->fib_metrics,
319  sizeof(u32) * RTAX_MAX) == 0 &&
320  ((nfi->fib_flags ^ fi->fib_flags) & ~RTNH_F_DEAD) == 0 &&
321  (nfi->fib_nhs == 0 || nh_comp(fi, nfi) == 0))
322  return fi;
323  }
324 
325  return NULL;
326 }
327 
328 /* Check, that the gateway is already configured.
329  * Used only by redirect accept routine.
330  */
331 int ip_fib_check_default(__be32 gw, struct net_device *dev)
332 {
333  struct hlist_head *head;
334  struct hlist_node *node;
335  struct fib_nh *nh;
336  unsigned int hash;
337 
338  spin_lock(&fib_info_lock);
339 
340  hash = fib_devindex_hashfn(dev->ifindex);
341  head = &fib_info_devhash[hash];
342  hlist_for_each_entry(nh, node, head, nh_hash) {
343  if (nh->nh_dev == dev &&
344  nh->nh_gw == gw &&
345  !(nh->nh_flags & RTNH_F_DEAD)) {
346  spin_unlock(&fib_info_lock);
347  return 0;
348  }
349  }
350 
351  spin_unlock(&fib_info_lock);
352 
353  return -1;
354 }
355 
356 static inline size_t fib_nlmsg_size(struct fib_info *fi)
357 {
358  size_t payload = NLMSG_ALIGN(sizeof(struct rtmsg))
359  + nla_total_size(4) /* RTA_TABLE */
360  + nla_total_size(4) /* RTA_DST */
361  + nla_total_size(4) /* RTA_PRIORITY */
362  + nla_total_size(4); /* RTA_PREFSRC */
363 
364  /* space for nested metrics */
365  payload += nla_total_size((RTAX_MAX * nla_total_size(4)));
366 
367  if (fi->fib_nhs) {
368  /* Also handles the special case fib_nhs == 1 */
369 
370  /* each nexthop is packed in an attribute */
371  size_t nhsize = nla_total_size(sizeof(struct rtnexthop));
372 
373  /* may contain flow and gateway attribute */
374  nhsize += 2 * nla_total_size(4);
375 
376  /* all nexthops are packed in a nested attribute */
377  payload += nla_total_size(fi->fib_nhs * nhsize);
378  }
379 
380  return payload;
381 }
382 
383 void rtmsg_fib(int event, __be32 key, struct fib_alias *fa,
384  int dst_len, u32 tb_id, struct nl_info *info,
385  unsigned int nlm_flags)
386 {
387  struct sk_buff *skb;
388  u32 seq = info->nlh ? info->nlh->nlmsg_seq : 0;
389  int err = -ENOBUFS;
390 
391  skb = nlmsg_new(fib_nlmsg_size(fa->fa_info), GFP_KERNEL);
392  if (skb == NULL)
393  goto errout;
394 
395  err = fib_dump_info(skb, info->portid, seq, event, tb_id,
396  fa->fa_type, key, dst_len,
397  fa->fa_tos, fa->fa_info, nlm_flags);
398  if (err < 0) {
399  /* -EMSGSIZE implies BUG in fib_nlmsg_size() */
400  WARN_ON(err == -EMSGSIZE);
401  kfree_skb(skb);
402  goto errout;
403  }
404  rtnl_notify(skb, info->nl_net, info->portid, RTNLGRP_IPV4_ROUTE,
405  info->nlh, GFP_KERNEL);
406  return;
407 errout:
408  if (err < 0)
409  rtnl_set_sk_err(info->nl_net, RTNLGRP_IPV4_ROUTE, err);
410 }
411 
412 /* Return the first fib alias matching TOS with
413  * priority less than or equal to PRIO.
414  */
415 struct fib_alias *fib_find_alias(struct list_head *fah, u8 tos, u32 prio)
416 {
417  if (fah) {
418  struct fib_alias *fa;
419  list_for_each_entry(fa, fah, fa_list) {
420  if (fa->fa_tos > tos)
421  continue;
422  if (fa->fa_info->fib_priority >= prio ||
423  fa->fa_tos < tos)
424  return fa;
425  }
426  }
427  return NULL;
428 }
429 
430 int fib_detect_death(struct fib_info *fi, int order,
431  struct fib_info **last_resort, int *last_idx, int dflt)
432 {
433  struct neighbour *n;
434  int state = NUD_NONE;
435 
436  n = neigh_lookup(&arp_tbl, &fi->fib_nh[0].nh_gw, fi->fib_dev);
437  if (n) {
438  state = n->nud_state;
439  neigh_release(n);
440  }
441  if (state == NUD_REACHABLE)
442  return 0;
443  if ((state & NUD_VALID) && order != dflt)
444  return 0;
445  if ((state & NUD_VALID) ||
446  (*last_idx < 0 && order > dflt)) {
447  *last_resort = fi;
448  *last_idx = order;
449  }
450  return 1;
451 }
452 
453 #ifdef CONFIG_IP_ROUTE_MULTIPATH
454 
455 static int fib_count_nexthops(struct rtnexthop *rtnh, int remaining)
456 {
457  int nhs = 0;
458 
459  while (rtnh_ok(rtnh, remaining)) {
460  nhs++;
461  rtnh = rtnh_next(rtnh, &remaining);
462  }
463 
464  /* leftover implies invalid nexthop configuration, discard it */
465  return remaining > 0 ? 0 : nhs;
466 }
467 
468 static int fib_get_nhs(struct fib_info *fi, struct rtnexthop *rtnh,
469  int remaining, struct fib_config *cfg)
470 {
471  change_nexthops(fi) {
472  int attrlen;
473 
474  if (!rtnh_ok(rtnh, remaining))
475  return -EINVAL;
476 
477  nexthop_nh->nh_flags =
478  (cfg->fc_flags & ~0xFF) | rtnh->rtnh_flags;
479  nexthop_nh->nh_oif = rtnh->rtnh_ifindex;
480  nexthop_nh->nh_weight = rtnh->rtnh_hops + 1;
481 
482  attrlen = rtnh_attrlen(rtnh);
483  if (attrlen > 0) {
484  struct nlattr *nla, *attrs = rtnh_attrs(rtnh);
485 
486  nla = nla_find(attrs, attrlen, RTA_GATEWAY);
487  nexthop_nh->nh_gw = nla ? nla_get_be32(nla) : 0;
488 #ifdef CONFIG_IP_ROUTE_CLASSID
489  nla = nla_find(attrs, attrlen, RTA_FLOW);
490  nexthop_nh->nh_tclassid = nla ? nla_get_u32(nla) : 0;
491  if (nexthop_nh->nh_tclassid)
492  fi->fib_net->ipv4.fib_num_tclassid_users++;
493 #endif
494  }
495 
496  rtnh = rtnh_next(rtnh, &remaining);
497  } endfor_nexthops(fi);
498 
499  return 0;
500 }
501 
502 #endif
503 
504 int fib_nh_match(struct fib_config *cfg, struct fib_info *fi)
505 {
506 #ifdef CONFIG_IP_ROUTE_MULTIPATH
507  struct rtnexthop *rtnh;
508  int remaining;
509 #endif
510 
511  if (cfg->fc_priority && cfg->fc_priority != fi->fib_priority)
512  return 1;
513 
514  if (cfg->fc_oif || cfg->fc_gw) {
515  if ((!cfg->fc_oif || cfg->fc_oif == fi->fib_nh->nh_oif) &&
516  (!cfg->fc_gw || cfg->fc_gw == fi->fib_nh->nh_gw))
517  return 0;
518  return 1;
519  }
520 
521 #ifdef CONFIG_IP_ROUTE_MULTIPATH
522  if (cfg->fc_mp == NULL)
523  return 0;
524 
525  rtnh = cfg->fc_mp;
526  remaining = cfg->fc_mp_len;
527 
528  for_nexthops(fi) {
529  int attrlen;
530 
531  if (!rtnh_ok(rtnh, remaining))
532  return -EINVAL;
533 
534  if (rtnh->rtnh_ifindex && rtnh->rtnh_ifindex != nh->nh_oif)
535  return 1;
536 
537  attrlen = rtnh_attrlen(rtnh);
538  if (attrlen < 0) {
539  struct nlattr *nla, *attrs = rtnh_attrs(rtnh);
540 
541  nla = nla_find(attrs, attrlen, RTA_GATEWAY);
542  if (nla && nla_get_be32(nla) != nh->nh_gw)
543  return 1;
544 #ifdef CONFIG_IP_ROUTE_CLASSID
545  nla = nla_find(attrs, attrlen, RTA_FLOW);
546  if (nla && nla_get_u32(nla) != nh->nh_tclassid)
547  return 1;
548 #endif
549  }
550 
551  rtnh = rtnh_next(rtnh, &remaining);
552  } endfor_nexthops(fi);
553 #endif
554  return 0;
555 }
556 
557 
558 /*
559  * Picture
560  * -------
561  *
562  * Semantics of nexthop is very messy by historical reasons.
563  * We have to take into account, that:
564  * a) gateway can be actually local interface address,
565  * so that gatewayed route is direct.
566  * b) gateway must be on-link address, possibly
567  * described not by an ifaddr, but also by a direct route.
568  * c) If both gateway and interface are specified, they should not
569  * contradict.
570  * d) If we use tunnel routes, gateway could be not on-link.
571  *
572  * Attempt to reconcile all of these (alas, self-contradictory) conditions
573  * results in pretty ugly and hairy code with obscure logic.
574  *
575  * I chose to generalized it instead, so that the size
576  * of code does not increase practically, but it becomes
577  * much more general.
578  * Every prefix is assigned a "scope" value: "host" is local address,
579  * "link" is direct route,
580  * [ ... "site" ... "interior" ... ]
581  * and "universe" is true gateway route with global meaning.
582  *
583  * Every prefix refers to a set of "nexthop"s (gw, oif),
584  * where gw must have narrower scope. This recursion stops
585  * when gw has LOCAL scope or if "nexthop" is declared ONLINK,
586  * which means that gw is forced to be on link.
587  *
588  * Code is still hairy, but now it is apparently logically
589  * consistent and very flexible. F.e. as by-product it allows
590  * to co-exists in peace independent exterior and interior
591  * routing processes.
592  *
593  * Normally it looks as following.
594  *
595  * {universe prefix} -> (gw, oif) [scope link]
596  * |
597  * |-> {link prefix} -> (gw, oif) [scope local]
598  * |
599  * |-> {local prefix} (terminal node)
600  */
601 static int fib_check_nh(struct fib_config *cfg, struct fib_info *fi,
602  struct fib_nh *nh)
603 {
604  int err;
605  struct net *net;
606  struct net_device *dev;
607 
608  net = cfg->fc_nlinfo.nl_net;
609  if (nh->nh_gw) {
610  struct fib_result res;
611 
612  if (nh->nh_flags & RTNH_F_ONLINK) {
613 
614  if (cfg->fc_scope >= RT_SCOPE_LINK)
615  return -EINVAL;
616  if (inet_addr_type(net, nh->nh_gw) != RTN_UNICAST)
617  return -EINVAL;
618  dev = __dev_get_by_index(net, nh->nh_oif);
619  if (!dev)
620  return -ENODEV;
621  if (!(dev->flags & IFF_UP))
622  return -ENETDOWN;
623  nh->nh_dev = dev;
624  dev_hold(dev);
625  nh->nh_scope = RT_SCOPE_LINK;
626  return 0;
627  }
628  rcu_read_lock();
629  {
630  struct flowi4 fl4 = {
631  .daddr = nh->nh_gw,
632  .flowi4_scope = cfg->fc_scope + 1,
633  .flowi4_oif = nh->nh_oif,
634  };
635 
636  /* It is not necessary, but requires a bit of thinking */
637  if (fl4.flowi4_scope < RT_SCOPE_LINK)
638  fl4.flowi4_scope = RT_SCOPE_LINK;
639  err = fib_lookup(net, &fl4, &res);
640  if (err) {
641  rcu_read_unlock();
642  return err;
643  }
644  }
645  err = -EINVAL;
646  if (res.type != RTN_UNICAST && res.type != RTN_LOCAL)
647  goto out;
648  nh->nh_scope = res.scope;
649  nh->nh_oif = FIB_RES_OIF(res);
650  nh->nh_dev = dev = FIB_RES_DEV(res);
651  if (!dev)
652  goto out;
653  dev_hold(dev);
654  err = (dev->flags & IFF_UP) ? 0 : -ENETDOWN;
655  } else {
656  struct in_device *in_dev;
657 
658  if (nh->nh_flags & (RTNH_F_PERVASIVE | RTNH_F_ONLINK))
659  return -EINVAL;
660 
661  rcu_read_lock();
662  err = -ENODEV;
663  in_dev = inetdev_by_index(net, nh->nh_oif);
664  if (in_dev == NULL)
665  goto out;
666  err = -ENETDOWN;
667  if (!(in_dev->dev->flags & IFF_UP))
668  goto out;
669  nh->nh_dev = in_dev->dev;
670  dev_hold(nh->nh_dev);
671  nh->nh_scope = RT_SCOPE_HOST;
672  err = 0;
673  }
674 out:
675  rcu_read_unlock();
676  return err;
677 }
678 
679 static inline unsigned int fib_laddr_hashfn(__be32 val)
680 {
681  unsigned int mask = (fib_info_hash_size - 1);
682 
683  return ((__force u32)val ^
684  ((__force u32)val >> 7) ^
685  ((__force u32)val >> 14)) & mask;
686 }
687 
688 static struct hlist_head *fib_info_hash_alloc(int bytes)
689 {
690  if (bytes <= PAGE_SIZE)
691  return kzalloc(bytes, GFP_KERNEL);
692  else
693  return (struct hlist_head *)
694  __get_free_pages(GFP_KERNEL | __GFP_ZERO,
695  get_order(bytes));
696 }
697 
698 static void fib_info_hash_free(struct hlist_head *hash, int bytes)
699 {
700  if (!hash)
701  return;
702 
703  if (bytes <= PAGE_SIZE)
704  kfree(hash);
705  else
706  free_pages((unsigned long) hash, get_order(bytes));
707 }
708 
709 static void fib_info_hash_move(struct hlist_head *new_info_hash,
710  struct hlist_head *new_laddrhash,
711  unsigned int new_size)
712 {
713  struct hlist_head *old_info_hash, *old_laddrhash;
714  unsigned int old_size = fib_info_hash_size;
715  unsigned int i, bytes;
716 
717  spin_lock_bh(&fib_info_lock);
718  old_info_hash = fib_info_hash;
719  old_laddrhash = fib_info_laddrhash;
720  fib_info_hash_size = new_size;
721 
722  for (i = 0; i < old_size; i++) {
723  struct hlist_head *head = &fib_info_hash[i];
724  struct hlist_node *node, *n;
725  struct fib_info *fi;
726 
727  hlist_for_each_entry_safe(fi, node, n, head, fib_hash) {
728  struct hlist_head *dest;
729  unsigned int new_hash;
730 
731  hlist_del(&fi->fib_hash);
732 
733  new_hash = fib_info_hashfn(fi);
734  dest = &new_info_hash[new_hash];
735  hlist_add_head(&fi->fib_hash, dest);
736  }
737  }
738  fib_info_hash = new_info_hash;
739 
740  for (i = 0; i < old_size; i++) {
741  struct hlist_head *lhead = &fib_info_laddrhash[i];
742  struct hlist_node *node, *n;
743  struct fib_info *fi;
744 
745  hlist_for_each_entry_safe(fi, node, n, lhead, fib_lhash) {
746  struct hlist_head *ldest;
747  unsigned int new_hash;
748 
749  hlist_del(&fi->fib_lhash);
750 
751  new_hash = fib_laddr_hashfn(fi->fib_prefsrc);
752  ldest = &new_laddrhash[new_hash];
753  hlist_add_head(&fi->fib_lhash, ldest);
754  }
755  }
756  fib_info_laddrhash = new_laddrhash;
757 
758  spin_unlock_bh(&fib_info_lock);
759 
760  bytes = old_size * sizeof(struct hlist_head *);
761  fib_info_hash_free(old_info_hash, bytes);
762  fib_info_hash_free(old_laddrhash, bytes);
763 }
764 
765 __be32 fib_info_update_nh_saddr(struct net *net, struct fib_nh *nh)
766 {
767  nh->nh_saddr = inet_select_addr(nh->nh_dev,
768  nh->nh_gw,
769  nh->nh_parent->fib_scope);
770  nh->nh_saddr_genid = atomic_read(&net->ipv4.dev_addr_genid);
771 
772  return nh->nh_saddr;
773 }
774 
775 struct fib_info *fib_create_info(struct fib_config *cfg)
776 {
777  int err;
778  struct fib_info *fi = NULL;
779  struct fib_info *ofi;
780  int nhs = 1;
781  struct net *net = cfg->fc_nlinfo.nl_net;
782 
783  if (cfg->fc_type > RTN_MAX)
784  goto err_inval;
785 
786  /* Fast check to catch the most weird cases */
787  if (fib_props[cfg->fc_type].scope > cfg->fc_scope)
788  goto err_inval;
789 
790 #ifdef CONFIG_IP_ROUTE_MULTIPATH
791  if (cfg->fc_mp) {
792  nhs = fib_count_nexthops(cfg->fc_mp, cfg->fc_mp_len);
793  if (nhs == 0)
794  goto err_inval;
795  }
796 #endif
797 
798  err = -ENOBUFS;
799  if (fib_info_cnt >= fib_info_hash_size) {
800  unsigned int new_size = fib_info_hash_size << 1;
801  struct hlist_head *new_info_hash;
802  struct hlist_head *new_laddrhash;
803  unsigned int bytes;
804 
805  if (!new_size)
806  new_size = 1;
807  bytes = new_size * sizeof(struct hlist_head *);
808  new_info_hash = fib_info_hash_alloc(bytes);
809  new_laddrhash = fib_info_hash_alloc(bytes);
810  if (!new_info_hash || !new_laddrhash) {
811  fib_info_hash_free(new_info_hash, bytes);
812  fib_info_hash_free(new_laddrhash, bytes);
813  } else
814  fib_info_hash_move(new_info_hash, new_laddrhash, new_size);
815 
816  if (!fib_info_hash_size)
817  goto failure;
818  }
819 
820  fi = kzalloc(sizeof(*fi)+nhs*sizeof(struct fib_nh), GFP_KERNEL);
821  if (fi == NULL)
822  goto failure;
823  if (cfg->fc_mx) {
824  fi->fib_metrics = kzalloc(sizeof(u32) * RTAX_MAX, GFP_KERNEL);
825  if (!fi->fib_metrics)
826  goto failure;
827  } else
828  fi->fib_metrics = (u32 *) dst_default_metrics;
829  fib_info_cnt++;
830 
831  fi->fib_net = hold_net(net);
832  fi->fib_protocol = cfg->fc_protocol;
833  fi->fib_scope = cfg->fc_scope;
834  fi->fib_flags = cfg->fc_flags;
835  fi->fib_priority = cfg->fc_priority;
836  fi->fib_prefsrc = cfg->fc_prefsrc;
837  fi->fib_type = cfg->fc_type;
838 
839  fi->fib_nhs = nhs;
840  change_nexthops(fi) {
841  nexthop_nh->nh_parent = fi;
842  nexthop_nh->nh_pcpu_rth_output = alloc_percpu(struct rtable __rcu *);
843  if (!nexthop_nh->nh_pcpu_rth_output)
844  goto failure;
845  } endfor_nexthops(fi)
846 
847  if (cfg->fc_mx) {
848  struct nlattr *nla;
849  int remaining;
850 
851  nla_for_each_attr(nla, cfg->fc_mx, cfg->fc_mx_len, remaining) {
852  int type = nla_type(nla);
853 
854  if (type) {
855  u32 val;
856 
857  if (type > RTAX_MAX)
858  goto err_inval;
859  val = nla_get_u32(nla);
860  if (type == RTAX_ADVMSS && val > 65535 - 40)
861  val = 65535 - 40;
862  if (type == RTAX_MTU && val > 65535 - 15)
863  val = 65535 - 15;
864  fi->fib_metrics[type - 1] = val;
865  }
866  }
867  }
868 
869  if (cfg->fc_mp) {
870 #ifdef CONFIG_IP_ROUTE_MULTIPATH
871  err = fib_get_nhs(fi, cfg->fc_mp, cfg->fc_mp_len, cfg);
872  if (err != 0)
873  goto failure;
874  if (cfg->fc_oif && fi->fib_nh->nh_oif != cfg->fc_oif)
875  goto err_inval;
876  if (cfg->fc_gw && fi->fib_nh->nh_gw != cfg->fc_gw)
877  goto err_inval;
878 #ifdef CONFIG_IP_ROUTE_CLASSID
879  if (cfg->fc_flow && fi->fib_nh->nh_tclassid != cfg->fc_flow)
880  goto err_inval;
881 #endif
882 #else
883  goto err_inval;
884 #endif
885  } else {
886  struct fib_nh *nh = fi->fib_nh;
887 
888  nh->nh_oif = cfg->fc_oif;
889  nh->nh_gw = cfg->fc_gw;
890  nh->nh_flags = cfg->fc_flags;
891 #ifdef CONFIG_IP_ROUTE_CLASSID
892  nh->nh_tclassid = cfg->fc_flow;
893  if (nh->nh_tclassid)
894  fi->fib_net->ipv4.fib_num_tclassid_users++;
895 #endif
896 #ifdef CONFIG_IP_ROUTE_MULTIPATH
897  nh->nh_weight = 1;
898 #endif
899  }
900 
901  if (fib_props[cfg->fc_type].error) {
902  if (cfg->fc_gw || cfg->fc_oif || cfg->fc_mp)
903  goto err_inval;
904  goto link_it;
905  } else {
906  switch (cfg->fc_type) {
907  case RTN_UNICAST:
908  case RTN_LOCAL:
909  case RTN_BROADCAST:
910  case RTN_ANYCAST:
911  case RTN_MULTICAST:
912  break;
913  default:
914  goto err_inval;
915  }
916  }
917 
918  if (cfg->fc_scope > RT_SCOPE_HOST)
919  goto err_inval;
920 
921  if (cfg->fc_scope == RT_SCOPE_HOST) {
922  struct fib_nh *nh = fi->fib_nh;
923 
924  /* Local address is added. */
925  if (nhs != 1 || nh->nh_gw)
926  goto err_inval;
927  nh->nh_scope = RT_SCOPE_NOWHERE;
928  nh->nh_dev = dev_get_by_index(net, fi->fib_nh->nh_oif);
929  err = -ENODEV;
930  if (nh->nh_dev == NULL)
931  goto failure;
932  } else {
933  change_nexthops(fi) {
934  err = fib_check_nh(cfg, fi, nexthop_nh);
935  if (err != 0)
936  goto failure;
937  } endfor_nexthops(fi)
938  }
939 
940  if (fi->fib_prefsrc) {
941  if (cfg->fc_type != RTN_LOCAL || !cfg->fc_dst ||
942  fi->fib_prefsrc != cfg->fc_dst)
943  if (inet_addr_type(net, fi->fib_prefsrc) != RTN_LOCAL)
944  goto err_inval;
945  }
946 
947  change_nexthops(fi) {
948  fib_info_update_nh_saddr(net, nexthop_nh);
949  } endfor_nexthops(fi)
950 
951 link_it:
952  ofi = fib_find_info(fi);
953  if (ofi) {
954  fi->fib_dead = 1;
955  free_fib_info(fi);
956  ofi->fib_treeref++;
957  return ofi;
958  }
959 
960  fi->fib_treeref++;
961  atomic_inc(&fi->fib_clntref);
962  spin_lock_bh(&fib_info_lock);
963  hlist_add_head(&fi->fib_hash,
964  &fib_info_hash[fib_info_hashfn(fi)]);
965  if (fi->fib_prefsrc) {
966  struct hlist_head *head;
967 
968  head = &fib_info_laddrhash[fib_laddr_hashfn(fi->fib_prefsrc)];
969  hlist_add_head(&fi->fib_lhash, head);
970  }
971  change_nexthops(fi) {
972  struct hlist_head *head;
973  unsigned int hash;
974 
975  if (!nexthop_nh->nh_dev)
976  continue;
977  hash = fib_devindex_hashfn(nexthop_nh->nh_dev->ifindex);
978  head = &fib_info_devhash[hash];
979  hlist_add_head(&nexthop_nh->nh_hash, head);
980  } endfor_nexthops(fi)
981  spin_unlock_bh(&fib_info_lock);
982  return fi;
983 
984 err_inval:
985  err = -EINVAL;
986 
987 failure:
988  if (fi) {
989  fi->fib_dead = 1;
990  free_fib_info(fi);
991  }
992 
993  return ERR_PTR(err);
994 }
995 
996 int fib_dump_info(struct sk_buff *skb, u32 portid, u32 seq, int event,
997  u32 tb_id, u8 type, __be32 dst, int dst_len, u8 tos,
998  struct fib_info *fi, unsigned int flags)
999 {
1000  struct nlmsghdr *nlh;
1001  struct rtmsg *rtm;
1002 
1003  nlh = nlmsg_put(skb, portid, seq, event, sizeof(*rtm), flags);
1004  if (nlh == NULL)
1005  return -EMSGSIZE;
1006 
1007  rtm = nlmsg_data(nlh);
1008  rtm->rtm_family = AF_INET;
1009  rtm->rtm_dst_len = dst_len;
1010  rtm->rtm_src_len = 0;
1011  rtm->rtm_tos = tos;
1012  if (tb_id < 256)
1013  rtm->rtm_table = tb_id;
1014  else
1015  rtm->rtm_table = RT_TABLE_COMPAT;
1016  if (nla_put_u32(skb, RTA_TABLE, tb_id))
1017  goto nla_put_failure;
1018  rtm->rtm_type = type;
1019  rtm->rtm_flags = fi->fib_flags;
1020  rtm->rtm_scope = fi->fib_scope;
1021  rtm->rtm_protocol = fi->fib_protocol;
1022 
1023  if (rtm->rtm_dst_len &&
1024  nla_put_be32(skb, RTA_DST, dst))
1025  goto nla_put_failure;
1026  if (fi->fib_priority &&
1027  nla_put_u32(skb, RTA_PRIORITY, fi->fib_priority))
1028  goto nla_put_failure;
1029  if (rtnetlink_put_metrics(skb, fi->fib_metrics) < 0)
1030  goto nla_put_failure;
1031 
1032  if (fi->fib_prefsrc &&
1033  nla_put_be32(skb, RTA_PREFSRC, fi->fib_prefsrc))
1034  goto nla_put_failure;
1035  if (fi->fib_nhs == 1) {
1036  if (fi->fib_nh->nh_gw &&
1037  nla_put_be32(skb, RTA_GATEWAY, fi->fib_nh->nh_gw))
1038  goto nla_put_failure;
1039  if (fi->fib_nh->nh_oif &&
1040  nla_put_u32(skb, RTA_OIF, fi->fib_nh->nh_oif))
1041  goto nla_put_failure;
1042 #ifdef CONFIG_IP_ROUTE_CLASSID
1043  if (fi->fib_nh[0].nh_tclassid &&
1044  nla_put_u32(skb, RTA_FLOW, fi->fib_nh[0].nh_tclassid))
1045  goto nla_put_failure;
1046 #endif
1047  }
1048 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1049  if (fi->fib_nhs > 1) {
1050  struct rtnexthop *rtnh;
1051  struct nlattr *mp;
1052 
1053  mp = nla_nest_start(skb, RTA_MULTIPATH);
1054  if (mp == NULL)
1055  goto nla_put_failure;
1056 
1057  for_nexthops(fi) {
1058  rtnh = nla_reserve_nohdr(skb, sizeof(*rtnh));
1059  if (rtnh == NULL)
1060  goto nla_put_failure;
1061 
1062  rtnh->rtnh_flags = nh->nh_flags & 0xFF;
1063  rtnh->rtnh_hops = nh->nh_weight - 1;
1064  rtnh->rtnh_ifindex = nh->nh_oif;
1065 
1066  if (nh->nh_gw &&
1067  nla_put_be32(skb, RTA_GATEWAY, nh->nh_gw))
1068  goto nla_put_failure;
1069 #ifdef CONFIG_IP_ROUTE_CLASSID
1070  if (nh->nh_tclassid &&
1071  nla_put_u32(skb, RTA_FLOW, nh->nh_tclassid))
1072  goto nla_put_failure;
1073 #endif
1074  /* length of rtnetlink header + attributes */
1075  rtnh->rtnh_len = nlmsg_get_pos(skb) - (void *) rtnh;
1076  } endfor_nexthops(fi);
1077 
1078  nla_nest_end(skb, mp);
1079  }
1080 #endif
1081  return nlmsg_end(skb, nlh);
1082 
1083 nla_put_failure:
1084  nlmsg_cancel(skb, nlh);
1085  return -EMSGSIZE;
1086 }
1087 
1088 /*
1089  * Update FIB if:
1090  * - local address disappeared -> we must delete all the entries
1091  * referring to it.
1092  * - device went down -> we must shutdown all nexthops going via it.
1093  */
1094 int fib_sync_down_addr(struct net *net, __be32 local)
1095 {
1096  int ret = 0;
1097  unsigned int hash = fib_laddr_hashfn(local);
1098  struct hlist_head *head = &fib_info_laddrhash[hash];
1099  struct hlist_node *node;
1100  struct fib_info *fi;
1101 
1102  if (fib_info_laddrhash == NULL || local == 0)
1103  return 0;
1104 
1105  hlist_for_each_entry(fi, node, head, fib_lhash) {
1106  if (!net_eq(fi->fib_net, net))
1107  continue;
1108  if (fi->fib_prefsrc == local) {
1109  fi->fib_flags |= RTNH_F_DEAD;
1110  ret++;
1111  }
1112  }
1113  return ret;
1114 }
1115 
1116 int fib_sync_down_dev(struct net_device *dev, int force)
1117 {
1118  int ret = 0;
1119  int scope = RT_SCOPE_NOWHERE;
1120  struct fib_info *prev_fi = NULL;
1121  unsigned int hash = fib_devindex_hashfn(dev->ifindex);
1122  struct hlist_head *head = &fib_info_devhash[hash];
1123  struct hlist_node *node;
1124  struct fib_nh *nh;
1125 
1126  if (force)
1127  scope = -1;
1128 
1129  hlist_for_each_entry(nh, node, head, nh_hash) {
1130  struct fib_info *fi = nh->nh_parent;
1131  int dead;
1132 
1133  BUG_ON(!fi->fib_nhs);
1134  if (nh->nh_dev != dev || fi == prev_fi)
1135  continue;
1136  prev_fi = fi;
1137  dead = 0;
1138  change_nexthops(fi) {
1139  if (nexthop_nh->nh_flags & RTNH_F_DEAD)
1140  dead++;
1141  else if (nexthop_nh->nh_dev == dev &&
1142  nexthop_nh->nh_scope != scope) {
1143  nexthop_nh->nh_flags |= RTNH_F_DEAD;
1144 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1145  spin_lock_bh(&fib_multipath_lock);
1146  fi->fib_power -= nexthop_nh->nh_power;
1147  nexthop_nh->nh_power = 0;
1148  spin_unlock_bh(&fib_multipath_lock);
1149 #endif
1150  dead++;
1151  }
1152 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1153  if (force > 1 && nexthop_nh->nh_dev == dev) {
1154  dead = fi->fib_nhs;
1155  break;
1156  }
1157 #endif
1158  } endfor_nexthops(fi)
1159  if (dead == fi->fib_nhs) {
1160  fi->fib_flags |= RTNH_F_DEAD;
1161  ret++;
1162  }
1163  }
1164 
1165  return ret;
1166 }
1167 
1168 /* Must be invoked inside of an RCU protected region. */
1169 void fib_select_default(struct fib_result *res)
1170 {
1171  struct fib_info *fi = NULL, *last_resort = NULL;
1172  struct list_head *fa_head = res->fa_head;
1173  struct fib_table *tb = res->table;
1174  int order = -1, last_idx = -1;
1175  struct fib_alias *fa;
1176 
1177  list_for_each_entry_rcu(fa, fa_head, fa_list) {
1178  struct fib_info *next_fi = fa->fa_info;
1179 
1180  if (next_fi->fib_scope != res->scope ||
1181  fa->fa_type != RTN_UNICAST)
1182  continue;
1183 
1184  if (next_fi->fib_priority > res->fi->fib_priority)
1185  break;
1186  if (!next_fi->fib_nh[0].nh_gw ||
1187  next_fi->fib_nh[0].nh_scope != RT_SCOPE_LINK)
1188  continue;
1189 
1190  fib_alias_accessed(fa);
1191 
1192  if (fi == NULL) {
1193  if (next_fi != res->fi)
1194  break;
1195  } else if (!fib_detect_death(fi, order, &last_resort,
1196  &last_idx, tb->tb_default)) {
1197  fib_result_assign(res, fi);
1198  tb->tb_default = order;
1199  goto out;
1200  }
1201  fi = next_fi;
1202  order++;
1203  }
1204 
1205  if (order <= 0 || fi == NULL) {
1206  tb->tb_default = -1;
1207  goto out;
1208  }
1209 
1210  if (!fib_detect_death(fi, order, &last_resort, &last_idx,
1211  tb->tb_default)) {
1212  fib_result_assign(res, fi);
1213  tb->tb_default = order;
1214  goto out;
1215  }
1216 
1217  if (last_idx >= 0)
1218  fib_result_assign(res, last_resort);
1219  tb->tb_default = last_idx;
1220 out:
1221  return;
1222 }
1223 
1224 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1225 
1226 /*
1227  * Dead device goes up. We wake up dead nexthops.
1228  * It takes sense only on multipath routes.
1229  */
1230 int fib_sync_up(struct net_device *dev)
1231 {
1232  struct fib_info *prev_fi;
1233  unsigned int hash;
1234  struct hlist_head *head;
1235  struct hlist_node *node;
1236  struct fib_nh *nh;
1237  int ret;
1238 
1239  if (!(dev->flags & IFF_UP))
1240  return 0;
1241 
1242  prev_fi = NULL;
1243  hash = fib_devindex_hashfn(dev->ifindex);
1244  head = &fib_info_devhash[hash];
1245  ret = 0;
1246 
1247  hlist_for_each_entry(nh, node, head, nh_hash) {
1248  struct fib_info *fi = nh->nh_parent;
1249  int alive;
1250 
1251  BUG_ON(!fi->fib_nhs);
1252  if (nh->nh_dev != dev || fi == prev_fi)
1253  continue;
1254 
1255  prev_fi = fi;
1256  alive = 0;
1257  change_nexthops(fi) {
1258  if (!(nexthop_nh->nh_flags & RTNH_F_DEAD)) {
1259  alive++;
1260  continue;
1261  }
1262  if (nexthop_nh->nh_dev == NULL ||
1263  !(nexthop_nh->nh_dev->flags & IFF_UP))
1264  continue;
1265  if (nexthop_nh->nh_dev != dev ||
1266  !__in_dev_get_rtnl(dev))
1267  continue;
1268  alive++;
1269  spin_lock_bh(&fib_multipath_lock);
1270  nexthop_nh->nh_power = 0;
1271  nexthop_nh->nh_flags &= ~RTNH_F_DEAD;
1272  spin_unlock_bh(&fib_multipath_lock);
1273  } endfor_nexthops(fi)
1274 
1275  if (alive > 0) {
1276  fi->fib_flags &= ~RTNH_F_DEAD;
1277  ret++;
1278  }
1279  }
1280 
1281  return ret;
1282 }
1283 
1284 /*
1285  * The algorithm is suboptimal, but it provides really
1286  * fair weighted route distribution.
1287  */
1288 void fib_select_multipath(struct fib_result *res)
1289 {
1290  struct fib_info *fi = res->fi;
1291  int w;
1292 
1293  spin_lock_bh(&fib_multipath_lock);
1294  if (fi->fib_power <= 0) {
1295  int power = 0;
1296  change_nexthops(fi) {
1297  if (!(nexthop_nh->nh_flags & RTNH_F_DEAD)) {
1298  power += nexthop_nh->nh_weight;
1299  nexthop_nh->nh_power = nexthop_nh->nh_weight;
1300  }
1301  } endfor_nexthops(fi);
1302  fi->fib_power = power;
1303  if (power <= 0) {
1304  spin_unlock_bh(&fib_multipath_lock);
1305  /* Race condition: route has just become dead. */
1306  res->nh_sel = 0;
1307  return;
1308  }
1309  }
1310 
1311 
1312  /* w should be random number [0..fi->fib_power-1],
1313  * it is pretty bad approximation.
1314  */
1315 
1316  w = jiffies % fi->fib_power;
1317 
1318  change_nexthops(fi) {
1319  if (!(nexthop_nh->nh_flags & RTNH_F_DEAD) &&
1320  nexthop_nh->nh_power) {
1321  w -= nexthop_nh->nh_power;
1322  if (w <= 0) {
1323  nexthop_nh->nh_power--;
1324  fi->fib_power--;
1325  res->nh_sel = nhsel;
1326  spin_unlock_bh(&fib_multipath_lock);
1327  return;
1328  }
1329  }
1330  } endfor_nexthops(fi);
1331 
1332  /* Race condition: route has just become dead. */
1333  res->nh_sel = 0;
1334  spin_unlock_bh(&fib_multipath_lock);
1335 }
1336 #endif
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