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TOMOYO Linux Cross Reference
Linux/net/ipv4/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, <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 <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 #include <net/lwtunnel.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 u32 fib_multipath_secret __read_mostly;
 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;
161         int i;
162 
163         hash = rcu_dereference_protected(nh->nh_exceptions, 1);
164         if (!hash)
165                 return;
166         for (i = 0; i < FNHE_HASH_SIZE; i++) {
167                 struct fib_nh_exception *fnhe;
168 
169                 fnhe = rcu_dereference_protected(hash[i].chain, 1);
170                 while (fnhe) {
171                         struct fib_nh_exception *next;
172                         
173                         next = rcu_dereference_protected(fnhe->fnhe_next, 1);
174 
175                         rt_fibinfo_free(&fnhe->fnhe_rth_input);
176                         rt_fibinfo_free(&fnhe->fnhe_rth_output);
177 
178                         kfree(fnhe);
179 
180                         fnhe = next;
181                 }
182         }
183         kfree(hash);
184 }
185 
186 static void rt_fibinfo_free_cpus(struct rtable __rcu * __percpu *rtp)
187 {
188         int cpu;
189 
190         if (!rtp)
191                 return;
192 
193         for_each_possible_cpu(cpu) {
194                 struct rtable *rt;
195 
196                 rt = rcu_dereference_protected(*per_cpu_ptr(rtp, cpu), 1);
197                 if (rt)
198                         dst_free(&rt->dst);
199         }
200         free_percpu(rtp);
201 }
202 
203 /* Release a nexthop info record */
204 static void free_fib_info_rcu(struct rcu_head *head)
205 {
206         struct fib_info *fi = container_of(head, struct fib_info, rcu);
207 
208         change_nexthops(fi) {
209                 if (nexthop_nh->nh_dev)
210                         dev_put(nexthop_nh->nh_dev);
211                 lwtstate_put(nexthop_nh->nh_lwtstate);
212                 free_nh_exceptions(nexthop_nh);
213                 rt_fibinfo_free_cpus(nexthop_nh->nh_pcpu_rth_output);
214                 rt_fibinfo_free(&nexthop_nh->nh_rth_input);
215         } endfor_nexthops(fi);
216 
217         if (fi->fib_metrics != (u32 *) dst_default_metrics)
218                 kfree(fi->fib_metrics);
219         kfree(fi);
220 }
221 
222 void free_fib_info(struct fib_info *fi)
223 {
224         if (fi->fib_dead == 0) {
225                 pr_warn("Freeing alive fib_info %p\n", fi);
226                 return;
227         }
228         fib_info_cnt--;
229 #ifdef CONFIG_IP_ROUTE_CLASSID
230         change_nexthops(fi) {
231                 if (nexthop_nh->nh_tclassid)
232                         fi->fib_net->ipv4.fib_num_tclassid_users--;
233         } endfor_nexthops(fi);
234 #endif
235         call_rcu(&fi->rcu, free_fib_info_rcu);
236 }
237 
238 void fib_release_info(struct fib_info *fi)
239 {
240         spin_lock_bh(&fib_info_lock);
241         if (fi && --fi->fib_treeref == 0) {
242                 hlist_del(&fi->fib_hash);
243                 if (fi->fib_prefsrc)
244                         hlist_del(&fi->fib_lhash);
245                 change_nexthops(fi) {
246                         if (!nexthop_nh->nh_dev)
247                                 continue;
248                         hlist_del(&nexthop_nh->nh_hash);
249                 } endfor_nexthops(fi)
250                 fi->fib_dead = 1;
251                 fib_info_put(fi);
252         }
253         spin_unlock_bh(&fib_info_lock);
254 }
255 
256 static inline int nh_comp(const struct fib_info *fi, const struct fib_info *ofi)
257 {
258         const struct fib_nh *onh = ofi->fib_nh;
259 
260         for_nexthops(fi) {
261                 if (nh->nh_oif != onh->nh_oif ||
262                     nh->nh_gw  != onh->nh_gw ||
263                     nh->nh_scope != onh->nh_scope ||
264 #ifdef CONFIG_IP_ROUTE_MULTIPATH
265                     nh->nh_weight != onh->nh_weight ||
266 #endif
267 #ifdef CONFIG_IP_ROUTE_CLASSID
268                     nh->nh_tclassid != onh->nh_tclassid ||
269 #endif
270                     lwtunnel_cmp_encap(nh->nh_lwtstate, onh->nh_lwtstate) ||
271                     ((nh->nh_flags ^ onh->nh_flags) & ~RTNH_COMPARE_MASK))
272                         return -1;
273                 onh++;
274         } endfor_nexthops(fi);
275         return 0;
276 }
277 
278 static inline unsigned int fib_devindex_hashfn(unsigned int val)
279 {
280         unsigned int mask = DEVINDEX_HASHSIZE - 1;
281 
282         return (val ^
283                 (val >> DEVINDEX_HASHBITS) ^
284                 (val >> (DEVINDEX_HASHBITS * 2))) & mask;
285 }
286 
287 static inline unsigned int fib_info_hashfn(const struct fib_info *fi)
288 {
289         unsigned int mask = (fib_info_hash_size - 1);
290         unsigned int val = fi->fib_nhs;
291 
292         val ^= (fi->fib_protocol << 8) | fi->fib_scope;
293         val ^= (__force u32)fi->fib_prefsrc;
294         val ^= fi->fib_priority;
295         for_nexthops(fi) {
296                 val ^= fib_devindex_hashfn(nh->nh_oif);
297         } endfor_nexthops(fi)
298 
299         return (val ^ (val >> 7) ^ (val >> 12)) & mask;
300 }
301 
302 static struct fib_info *fib_find_info(const struct fib_info *nfi)
303 {
304         struct hlist_head *head;
305         struct fib_info *fi;
306         unsigned int hash;
307 
308         hash = fib_info_hashfn(nfi);
309         head = &fib_info_hash[hash];
310 
311         hlist_for_each_entry(fi, head, fib_hash) {
312                 if (!net_eq(fi->fib_net, nfi->fib_net))
313                         continue;
314                 if (fi->fib_nhs != nfi->fib_nhs)
315                         continue;
316                 if (nfi->fib_protocol == fi->fib_protocol &&
317                     nfi->fib_scope == fi->fib_scope &&
318                     nfi->fib_prefsrc == fi->fib_prefsrc &&
319                     nfi->fib_priority == fi->fib_priority &&
320                     nfi->fib_type == fi->fib_type &&
321                     memcmp(nfi->fib_metrics, fi->fib_metrics,
322                            sizeof(u32) * RTAX_MAX) == 0 &&
323                     !((nfi->fib_flags ^ fi->fib_flags) & ~RTNH_COMPARE_MASK) &&
324                     (nfi->fib_nhs == 0 || nh_comp(fi, nfi) == 0))
325                         return fi;
326         }
327 
328         return NULL;
329 }
330 
331 /* Check, that the gateway is already configured.
332  * Used only by redirect accept routine.
333  */
334 int ip_fib_check_default(__be32 gw, struct net_device *dev)
335 {
336         struct hlist_head *head;
337         struct fib_nh *nh;
338         unsigned int hash;
339 
340         spin_lock(&fib_info_lock);
341 
342         hash = fib_devindex_hashfn(dev->ifindex);
343         head = &fib_info_devhash[hash];
344         hlist_for_each_entry(nh, head, nh_hash) {
345                 if (nh->nh_dev == dev &&
346                     nh->nh_gw == gw &&
347                     !(nh->nh_flags & RTNH_F_DEAD)) {
348                         spin_unlock(&fib_info_lock);
349                         return 0;
350                 }
351         }
352 
353         spin_unlock(&fib_info_lock);
354 
355         return -1;
356 }
357 
358 static inline size_t fib_nlmsg_size(struct fib_info *fi)
359 {
360         size_t payload = NLMSG_ALIGN(sizeof(struct rtmsg))
361                          + nla_total_size(4) /* RTA_TABLE */
362                          + nla_total_size(4) /* RTA_DST */
363                          + nla_total_size(4) /* RTA_PRIORITY */
364                          + nla_total_size(4) /* RTA_PREFSRC */
365                          + nla_total_size(TCP_CA_NAME_MAX); /* RTAX_CC_ALGO */
366 
367         /* space for nested metrics */
368         payload += nla_total_size((RTAX_MAX * nla_total_size(4)));
369 
370         if (fi->fib_nhs) {
371                 size_t nh_encapsize = 0;
372                 /* Also handles the special case fib_nhs == 1 */
373 
374                 /* each nexthop is packed in an attribute */
375                 size_t nhsize = nla_total_size(sizeof(struct rtnexthop));
376 
377                 /* may contain flow and gateway attribute */
378                 nhsize += 2 * nla_total_size(4);
379 
380                 /* grab encap info */
381                 for_nexthops(fi) {
382                         if (nh->nh_lwtstate) {
383                                 /* RTA_ENCAP_TYPE */
384                                 nh_encapsize += lwtunnel_get_encap_size(
385                                                 nh->nh_lwtstate);
386                                 /* RTA_ENCAP */
387                                 nh_encapsize +=  nla_total_size(2);
388                         }
389                 } endfor_nexthops(fi);
390 
391                 /* all nexthops are packed in a nested attribute */
392                 payload += nla_total_size((fi->fib_nhs * nhsize) +
393                                           nh_encapsize);
394 
395         }
396 
397         return payload;
398 }
399 
400 void rtmsg_fib(int event, __be32 key, struct fib_alias *fa,
401                int dst_len, u32 tb_id, const struct nl_info *info,
402                unsigned int nlm_flags)
403 {
404         struct sk_buff *skb;
405         u32 seq = info->nlh ? info->nlh->nlmsg_seq : 0;
406         int err = -ENOBUFS;
407 
408         skb = nlmsg_new(fib_nlmsg_size(fa->fa_info), GFP_KERNEL);
409         if (!skb)
410                 goto errout;
411 
412         err = fib_dump_info(skb, info->portid, seq, event, tb_id,
413                             fa->fa_type, key, dst_len,
414                             fa->fa_tos, fa->fa_info, nlm_flags);
415         if (err < 0) {
416                 /* -EMSGSIZE implies BUG in fib_nlmsg_size() */
417                 WARN_ON(err == -EMSGSIZE);
418                 kfree_skb(skb);
419                 goto errout;
420         }
421         rtnl_notify(skb, info->nl_net, info->portid, RTNLGRP_IPV4_ROUTE,
422                     info->nlh, GFP_KERNEL);
423         return;
424 errout:
425         if (err < 0)
426                 rtnl_set_sk_err(info->nl_net, RTNLGRP_IPV4_ROUTE, err);
427 }
428 
429 static int fib_detect_death(struct fib_info *fi, int order,
430                             struct fib_info **last_resort, int *last_idx,
431                             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         } else {
441                 return 0;
442         }
443         if (state == NUD_REACHABLE)
444                 return 0;
445         if ((state & NUD_VALID) && order != dflt)
446                 return 0;
447         if ((state & NUD_VALID) ||
448             (*last_idx < 0 && order > dflt && state != NUD_INCOMPLETE)) {
449                 *last_resort = fi;
450                 *last_idx = order;
451         }
452         return 1;
453 }
454 
455 #ifdef CONFIG_IP_ROUTE_MULTIPATH
456 
457 static int fib_count_nexthops(struct rtnexthop *rtnh, int remaining)
458 {
459         int nhs = 0;
460 
461         while (rtnh_ok(rtnh, remaining)) {
462                 nhs++;
463                 rtnh = rtnh_next(rtnh, &remaining);
464         }
465 
466         /* leftover implies invalid nexthop configuration, discard it */
467         return remaining > 0 ? 0 : nhs;
468 }
469 
470 static int fib_get_nhs(struct fib_info *fi, struct rtnexthop *rtnh,
471                        int remaining, struct fib_config *cfg)
472 {
473         struct net *net = cfg->fc_nlinfo.nl_net;
474         int ret;
475 
476         change_nexthops(fi) {
477                 int attrlen;
478 
479                 if (!rtnh_ok(rtnh, remaining))
480                         return -EINVAL;
481 
482                 if (rtnh->rtnh_flags & (RTNH_F_DEAD | RTNH_F_LINKDOWN))
483                         return -EINVAL;
484 
485                 nexthop_nh->nh_flags =
486                         (cfg->fc_flags & ~0xFF) | rtnh->rtnh_flags;
487                 nexthop_nh->nh_oif = rtnh->rtnh_ifindex;
488                 nexthop_nh->nh_weight = rtnh->rtnh_hops + 1;
489 
490                 attrlen = rtnh_attrlen(rtnh);
491                 if (attrlen > 0) {
492                         struct nlattr *nla, *attrs = rtnh_attrs(rtnh);
493 
494                         nla = nla_find(attrs, attrlen, RTA_GATEWAY);
495                         nexthop_nh->nh_gw = nla ? nla_get_in_addr(nla) : 0;
496 #ifdef CONFIG_IP_ROUTE_CLASSID
497                         nla = nla_find(attrs, attrlen, RTA_FLOW);
498                         nexthop_nh->nh_tclassid = nla ? nla_get_u32(nla) : 0;
499                         if (nexthop_nh->nh_tclassid)
500                                 fi->fib_net->ipv4.fib_num_tclassid_users++;
501 #endif
502                         nla = nla_find(attrs, attrlen, RTA_ENCAP);
503                         if (nla) {
504                                 struct lwtunnel_state *lwtstate;
505                                 struct net_device *dev = NULL;
506                                 struct nlattr *nla_entype;
507 
508                                 nla_entype = nla_find(attrs, attrlen,
509                                                       RTA_ENCAP_TYPE);
510                                 if (!nla_entype)
511                                         goto err_inval;
512                                 if (cfg->fc_oif)
513                                         dev = __dev_get_by_index(net, cfg->fc_oif);
514                                 ret = lwtunnel_build_state(dev, nla_get_u16(
515                                                            nla_entype),
516                                                            nla,  AF_INET, cfg,
517                                                            &lwtstate);
518                                 if (ret)
519                                         goto errout;
520                                 nexthop_nh->nh_lwtstate =
521                                         lwtstate_get(lwtstate);
522                         }
523                 }
524 
525                 rtnh = rtnh_next(rtnh, &remaining);
526         } endfor_nexthops(fi);
527 
528         return 0;
529 
530 err_inval:
531         ret = -EINVAL;
532 
533 errout:
534         return ret;
535 }
536 
537 static void fib_rebalance(struct fib_info *fi)
538 {
539         int total;
540         int w;
541         struct in_device *in_dev;
542 
543         if (fi->fib_nhs < 2)
544                 return;
545 
546         total = 0;
547         for_nexthops(fi) {
548                 if (nh->nh_flags & RTNH_F_DEAD)
549                         continue;
550 
551                 in_dev = __in_dev_get_rtnl(nh->nh_dev);
552 
553                 if (in_dev &&
554                     IN_DEV_IGNORE_ROUTES_WITH_LINKDOWN(in_dev) &&
555                     nh->nh_flags & RTNH_F_LINKDOWN)
556                         continue;
557 
558                 total += nh->nh_weight;
559         } endfor_nexthops(fi);
560 
561         w = 0;
562         change_nexthops(fi) {
563                 int upper_bound;
564 
565                 in_dev = __in_dev_get_rtnl(nexthop_nh->nh_dev);
566 
567                 if (nexthop_nh->nh_flags & RTNH_F_DEAD) {
568                         upper_bound = -1;
569                 } else if (in_dev &&
570                            IN_DEV_IGNORE_ROUTES_WITH_LINKDOWN(in_dev) &&
571                            nexthop_nh->nh_flags & RTNH_F_LINKDOWN) {
572                         upper_bound = -1;
573                 } else {
574                         w += nexthop_nh->nh_weight;
575                         upper_bound = DIV_ROUND_CLOSEST_ULL((u64)w << 31,
576                                                             total) - 1;
577                 }
578 
579                 atomic_set(&nexthop_nh->nh_upper_bound, upper_bound);
580         } endfor_nexthops(fi);
581 
582         net_get_random_once(&fib_multipath_secret,
583                             sizeof(fib_multipath_secret));
584 }
585 
586 static inline void fib_add_weight(struct fib_info *fi,
587                                   const struct fib_nh *nh)
588 {
589         fi->fib_weight += nh->nh_weight;
590 }
591 
592 #else /* CONFIG_IP_ROUTE_MULTIPATH */
593 
594 #define fib_rebalance(fi) do { } while (0)
595 #define fib_add_weight(fi, nh) do { } while (0)
596 
597 #endif /* CONFIG_IP_ROUTE_MULTIPATH */
598 
599 static int fib_encap_match(struct net *net, u16 encap_type,
600                            struct nlattr *encap,
601                            int oif, const struct fib_nh *nh,
602                            const struct fib_config *cfg)
603 {
604         struct lwtunnel_state *lwtstate;
605         struct net_device *dev = NULL;
606         int ret, result = 0;
607 
608         if (encap_type == LWTUNNEL_ENCAP_NONE)
609                 return 0;
610 
611         if (oif)
612                 dev = __dev_get_by_index(net, oif);
613         ret = lwtunnel_build_state(dev, encap_type, encap,
614                                    AF_INET, cfg, &lwtstate);
615         if (!ret) {
616                 result = lwtunnel_cmp_encap(lwtstate, nh->nh_lwtstate);
617                 lwtstate_free(lwtstate);
618         }
619 
620         return result;
621 }
622 
623 int fib_nh_match(struct fib_config *cfg, struct fib_info *fi)
624 {
625         struct net *net = cfg->fc_nlinfo.nl_net;
626 #ifdef CONFIG_IP_ROUTE_MULTIPATH
627         struct rtnexthop *rtnh;
628         int remaining;
629 #endif
630 
631         if (cfg->fc_priority && cfg->fc_priority != fi->fib_priority)
632                 return 1;
633 
634         if (cfg->fc_oif || cfg->fc_gw) {
635                 if (cfg->fc_encap) {
636                         if (fib_encap_match(net, cfg->fc_encap_type,
637                                             cfg->fc_encap, cfg->fc_oif,
638                                             fi->fib_nh, cfg))
639                             return 1;
640                 }
641                 if ((!cfg->fc_oif || cfg->fc_oif == fi->fib_nh->nh_oif) &&
642                     (!cfg->fc_gw  || cfg->fc_gw == fi->fib_nh->nh_gw))
643                         return 0;
644                 return 1;
645         }
646 
647 #ifdef CONFIG_IP_ROUTE_MULTIPATH
648         if (!cfg->fc_mp)
649                 return 0;
650 
651         rtnh = cfg->fc_mp;
652         remaining = cfg->fc_mp_len;
653 
654         for_nexthops(fi) {
655                 int attrlen;
656 
657                 if (!rtnh_ok(rtnh, remaining))
658                         return -EINVAL;
659 
660                 if (rtnh->rtnh_ifindex && rtnh->rtnh_ifindex != nh->nh_oif)
661                         return 1;
662 
663                 attrlen = rtnh_attrlen(rtnh);
664                 if (attrlen > 0) {
665                         struct nlattr *nla, *attrs = rtnh_attrs(rtnh);
666 
667                         nla = nla_find(attrs, attrlen, RTA_GATEWAY);
668                         if (nla && nla_get_in_addr(nla) != nh->nh_gw)
669                                 return 1;
670 #ifdef CONFIG_IP_ROUTE_CLASSID
671                         nla = nla_find(attrs, attrlen, RTA_FLOW);
672                         if (nla && nla_get_u32(nla) != nh->nh_tclassid)
673                                 return 1;
674 #endif
675                 }
676 
677                 rtnh = rtnh_next(rtnh, &remaining);
678         } endfor_nexthops(fi);
679 #endif
680         return 0;
681 }
682 
683 
684 /*
685  * Picture
686  * -------
687  *
688  * Semantics of nexthop is very messy by historical reasons.
689  * We have to take into account, that:
690  * a) gateway can be actually local interface address,
691  *    so that gatewayed route is direct.
692  * b) gateway must be on-link address, possibly
693  *    described not by an ifaddr, but also by a direct route.
694  * c) If both gateway and interface are specified, they should not
695  *    contradict.
696  * d) If we use tunnel routes, gateway could be not on-link.
697  *
698  * Attempt to reconcile all of these (alas, self-contradictory) conditions
699  * results in pretty ugly and hairy code with obscure logic.
700  *
701  * I chose to generalized it instead, so that the size
702  * of code does not increase practically, but it becomes
703  * much more general.
704  * Every prefix is assigned a "scope" value: "host" is local address,
705  * "link" is direct route,
706  * [ ... "site" ... "interior" ... ]
707  * and "universe" is true gateway route with global meaning.
708  *
709  * Every prefix refers to a set of "nexthop"s (gw, oif),
710  * where gw must have narrower scope. This recursion stops
711  * when gw has LOCAL scope or if "nexthop" is declared ONLINK,
712  * which means that gw is forced to be on link.
713  *
714  * Code is still hairy, but now it is apparently logically
715  * consistent and very flexible. F.e. as by-product it allows
716  * to co-exists in peace independent exterior and interior
717  * routing processes.
718  *
719  * Normally it looks as following.
720  *
721  * {universe prefix}  -> (gw, oif) [scope link]
722  *                |
723  *                |-> {link prefix} -> (gw, oif) [scope local]
724  *                                      |
725  *                                      |-> {local prefix} (terminal node)
726  */
727 static int fib_check_nh(struct fib_config *cfg, struct fib_info *fi,
728                         struct fib_nh *nh)
729 {
730         int err = 0;
731         struct net *net;
732         struct net_device *dev;
733 
734         net = cfg->fc_nlinfo.nl_net;
735         if (nh->nh_gw) {
736                 struct fib_result res;
737 
738                 if (nh->nh_flags & RTNH_F_ONLINK) {
739                         unsigned int addr_type;
740 
741                         if (cfg->fc_scope >= RT_SCOPE_LINK)
742                                 return -EINVAL;
743                         dev = __dev_get_by_index(net, nh->nh_oif);
744                         if (!dev)
745                                 return -ENODEV;
746                         if (!(dev->flags & IFF_UP))
747                                 return -ENETDOWN;
748                         addr_type = inet_addr_type_dev_table(net, dev, nh->nh_gw);
749                         if (addr_type != RTN_UNICAST)
750                                 return -EINVAL;
751                         if (!netif_carrier_ok(dev))
752                                 nh->nh_flags |= RTNH_F_LINKDOWN;
753                         nh->nh_dev = dev;
754                         dev_hold(dev);
755                         nh->nh_scope = RT_SCOPE_LINK;
756                         return 0;
757                 }
758                 rcu_read_lock();
759                 {
760                         struct fib_table *tbl = NULL;
761                         struct flowi4 fl4 = {
762                                 .daddr = nh->nh_gw,
763                                 .flowi4_scope = cfg->fc_scope + 1,
764                                 .flowi4_oif = nh->nh_oif,
765                                 .flowi4_iif = LOOPBACK_IFINDEX,
766                         };
767 
768                         /* It is not necessary, but requires a bit of thinking */
769                         if (fl4.flowi4_scope < RT_SCOPE_LINK)
770                                 fl4.flowi4_scope = RT_SCOPE_LINK;
771 
772                         if (cfg->fc_table)
773                                 tbl = fib_get_table(net, cfg->fc_table);
774 
775                         if (tbl)
776                                 err = fib_table_lookup(tbl, &fl4, &res,
777                                                        FIB_LOOKUP_IGNORE_LINKSTATE |
778                                                        FIB_LOOKUP_NOREF);
779 
780                         /* on error or if no table given do full lookup. This
781                          * is needed for example when nexthops are in the local
782                          * table rather than the given table
783                          */
784                         if (!tbl || err) {
785                                 err = fib_lookup(net, &fl4, &res,
786                                                  FIB_LOOKUP_IGNORE_LINKSTATE);
787                         }
788 
789                         if (err) {
790                                 rcu_read_unlock();
791                                 return err;
792                         }
793                 }
794                 err = -EINVAL;
795                 if (res.type != RTN_UNICAST && res.type != RTN_LOCAL)
796                         goto out;
797                 nh->nh_scope = res.scope;
798                 nh->nh_oif = FIB_RES_OIF(res);
799                 nh->nh_dev = dev = FIB_RES_DEV(res);
800                 if (!dev)
801                         goto out;
802                 dev_hold(dev);
803                 if (!netif_carrier_ok(dev))
804                         nh->nh_flags |= RTNH_F_LINKDOWN;
805                 err = (dev->flags & IFF_UP) ? 0 : -ENETDOWN;
806         } else {
807                 struct in_device *in_dev;
808 
809                 if (nh->nh_flags & (RTNH_F_PERVASIVE | RTNH_F_ONLINK))
810                         return -EINVAL;
811 
812                 rcu_read_lock();
813                 err = -ENODEV;
814                 in_dev = inetdev_by_index(net, nh->nh_oif);
815                 if (!in_dev)
816                         goto out;
817                 err = -ENETDOWN;
818                 if (!(in_dev->dev->flags & IFF_UP))
819                         goto out;
820                 nh->nh_dev = in_dev->dev;
821                 dev_hold(nh->nh_dev);
822                 nh->nh_scope = RT_SCOPE_HOST;
823                 if (!netif_carrier_ok(nh->nh_dev))
824                         nh->nh_flags |= RTNH_F_LINKDOWN;
825                 err = 0;
826         }
827 out:
828         rcu_read_unlock();
829         return err;
830 }
831 
832 static inline unsigned int fib_laddr_hashfn(__be32 val)
833 {
834         unsigned int mask = (fib_info_hash_size - 1);
835 
836         return ((__force u32)val ^
837                 ((__force u32)val >> 7) ^
838                 ((__force u32)val >> 14)) & mask;
839 }
840 
841 static struct hlist_head *fib_info_hash_alloc(int bytes)
842 {
843         if (bytes <= PAGE_SIZE)
844                 return kzalloc(bytes, GFP_KERNEL);
845         else
846                 return (struct hlist_head *)
847                         __get_free_pages(GFP_KERNEL | __GFP_ZERO,
848                                          get_order(bytes));
849 }
850 
851 static void fib_info_hash_free(struct hlist_head *hash, int bytes)
852 {
853         if (!hash)
854                 return;
855 
856         if (bytes <= PAGE_SIZE)
857                 kfree(hash);
858         else
859                 free_pages((unsigned long) hash, get_order(bytes));
860 }
861 
862 static void fib_info_hash_move(struct hlist_head *new_info_hash,
863                                struct hlist_head *new_laddrhash,
864                                unsigned int new_size)
865 {
866         struct hlist_head *old_info_hash, *old_laddrhash;
867         unsigned int old_size = fib_info_hash_size;
868         unsigned int i, bytes;
869 
870         spin_lock_bh(&fib_info_lock);
871         old_info_hash = fib_info_hash;
872         old_laddrhash = fib_info_laddrhash;
873         fib_info_hash_size = new_size;
874 
875         for (i = 0; i < old_size; i++) {
876                 struct hlist_head *head = &fib_info_hash[i];
877                 struct hlist_node *n;
878                 struct fib_info *fi;
879 
880                 hlist_for_each_entry_safe(fi, n, head, fib_hash) {
881                         struct hlist_head *dest;
882                         unsigned int new_hash;
883 
884                         new_hash = fib_info_hashfn(fi);
885                         dest = &new_info_hash[new_hash];
886                         hlist_add_head(&fi->fib_hash, dest);
887                 }
888         }
889         fib_info_hash = new_info_hash;
890 
891         for (i = 0; i < old_size; i++) {
892                 struct hlist_head *lhead = &fib_info_laddrhash[i];
893                 struct hlist_node *n;
894                 struct fib_info *fi;
895 
896                 hlist_for_each_entry_safe(fi, n, lhead, fib_lhash) {
897                         struct hlist_head *ldest;
898                         unsigned int new_hash;
899 
900                         new_hash = fib_laddr_hashfn(fi->fib_prefsrc);
901                         ldest = &new_laddrhash[new_hash];
902                         hlist_add_head(&fi->fib_lhash, ldest);
903                 }
904         }
905         fib_info_laddrhash = new_laddrhash;
906 
907         spin_unlock_bh(&fib_info_lock);
908 
909         bytes = old_size * sizeof(struct hlist_head *);
910         fib_info_hash_free(old_info_hash, bytes);
911         fib_info_hash_free(old_laddrhash, bytes);
912 }
913 
914 __be32 fib_info_update_nh_saddr(struct net *net, struct fib_nh *nh)
915 {
916         nh->nh_saddr = inet_select_addr(nh->nh_dev,
917                                         nh->nh_gw,
918                                         nh->nh_parent->fib_scope);
919         nh->nh_saddr_genid = atomic_read(&net->ipv4.dev_addr_genid);
920 
921         return nh->nh_saddr;
922 }
923 
924 static bool fib_valid_prefsrc(struct fib_config *cfg, __be32 fib_prefsrc)
925 {
926         if (cfg->fc_type != RTN_LOCAL || !cfg->fc_dst ||
927             fib_prefsrc != cfg->fc_dst) {
928                 u32 tb_id = cfg->fc_table;
929                 int rc;
930 
931                 if (tb_id == RT_TABLE_MAIN)
932                         tb_id = RT_TABLE_LOCAL;
933 
934                 rc = inet_addr_type_table(cfg->fc_nlinfo.nl_net,
935                                           fib_prefsrc, tb_id);
936 
937                 if (rc != RTN_LOCAL && tb_id != RT_TABLE_LOCAL) {
938                         rc = inet_addr_type_table(cfg->fc_nlinfo.nl_net,
939                                                   fib_prefsrc, RT_TABLE_LOCAL);
940                 }
941 
942                 if (rc != RTN_LOCAL)
943                         return false;
944         }
945         return true;
946 }
947 
948 static int
949 fib_convert_metrics(struct fib_info *fi, const struct fib_config *cfg)
950 {
951         bool ecn_ca = false;
952         struct nlattr *nla;
953         int remaining;
954 
955         if (!cfg->fc_mx)
956                 return 0;
957 
958         nla_for_each_attr(nla, cfg->fc_mx, cfg->fc_mx_len, remaining) {
959                 int type = nla_type(nla);
960                 u32 val;
961 
962                 if (!type)
963                         continue;
964                 if (type > RTAX_MAX)
965                         return -EINVAL;
966 
967                 if (type == RTAX_CC_ALGO) {
968                         char tmp[TCP_CA_NAME_MAX];
969 
970                         nla_strlcpy(tmp, nla, sizeof(tmp));
971                         val = tcp_ca_get_key_by_name(tmp, &ecn_ca);
972                         if (val == TCP_CA_UNSPEC)
973                                 return -EINVAL;
974                 } else {
975                         val = nla_get_u32(nla);
976                 }
977                 if (type == RTAX_ADVMSS && val > 65535 - 40)
978                         val = 65535 - 40;
979                 if (type == RTAX_MTU && val > 65535 - 15)
980                         val = 65535 - 15;
981                 if (type == RTAX_HOPLIMIT && val > 255)
982                         val = 255;
983                 if (type == RTAX_FEATURES && (val & ~RTAX_FEATURE_MASK))
984                         return -EINVAL;
985                 fi->fib_metrics[type - 1] = val;
986         }
987 
988         if (ecn_ca)
989                 fi->fib_metrics[RTAX_FEATURES - 1] |= DST_FEATURE_ECN_CA;
990 
991         return 0;
992 }
993 
994 struct fib_info *fib_create_info(struct fib_config *cfg)
995 {
996         int err;
997         struct fib_info *fi = NULL;
998         struct fib_info *ofi;
999         int nhs = 1;
1000         struct net *net = cfg->fc_nlinfo.nl_net;
1001 
1002         if (cfg->fc_type > RTN_MAX)
1003                 goto err_inval;
1004 
1005         /* Fast check to catch the most weird cases */
1006         if (fib_props[cfg->fc_type].scope > cfg->fc_scope)
1007                 goto err_inval;
1008 
1009         if (cfg->fc_flags & (RTNH_F_DEAD | RTNH_F_LINKDOWN))
1010                 goto err_inval;
1011 
1012 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1013         if (cfg->fc_mp) {
1014                 nhs = fib_count_nexthops(cfg->fc_mp, cfg->fc_mp_len);
1015                 if (nhs == 0)
1016                         goto err_inval;
1017         }
1018 #endif
1019 
1020         err = -ENOBUFS;
1021         if (fib_info_cnt >= fib_info_hash_size) {
1022                 unsigned int new_size = fib_info_hash_size << 1;
1023                 struct hlist_head *new_info_hash;
1024                 struct hlist_head *new_laddrhash;
1025                 unsigned int bytes;
1026 
1027                 if (!new_size)
1028                         new_size = 16;
1029                 bytes = new_size * sizeof(struct hlist_head *);
1030                 new_info_hash = fib_info_hash_alloc(bytes);
1031                 new_laddrhash = fib_info_hash_alloc(bytes);
1032                 if (!new_info_hash || !new_laddrhash) {
1033                         fib_info_hash_free(new_info_hash, bytes);
1034                         fib_info_hash_free(new_laddrhash, bytes);
1035                 } else
1036                         fib_info_hash_move(new_info_hash, new_laddrhash, new_size);
1037 
1038                 if (!fib_info_hash_size)
1039                         goto failure;
1040         }
1041 
1042         fi = kzalloc(sizeof(*fi)+nhs*sizeof(struct fib_nh), GFP_KERNEL);
1043         if (!fi)
1044                 goto failure;
1045         fib_info_cnt++;
1046         if (cfg->fc_mx) {
1047                 fi->fib_metrics = kzalloc(sizeof(u32) * RTAX_MAX, GFP_KERNEL);
1048                 if (!fi->fib_metrics)
1049                         goto failure;
1050         } else
1051                 fi->fib_metrics = (u32 *) dst_default_metrics;
1052 
1053         fi->fib_net = net;
1054         fi->fib_protocol = cfg->fc_protocol;
1055         fi->fib_scope = cfg->fc_scope;
1056         fi->fib_flags = cfg->fc_flags;
1057         fi->fib_priority = cfg->fc_priority;
1058         fi->fib_prefsrc = cfg->fc_prefsrc;
1059         fi->fib_type = cfg->fc_type;
1060         fi->fib_tb_id = cfg->fc_table;
1061 
1062         fi->fib_nhs = nhs;
1063         change_nexthops(fi) {
1064                 nexthop_nh->nh_parent = fi;
1065                 nexthop_nh->nh_pcpu_rth_output = alloc_percpu(struct rtable __rcu *);
1066                 if (!nexthop_nh->nh_pcpu_rth_output)
1067                         goto failure;
1068         } endfor_nexthops(fi)
1069 
1070         err = fib_convert_metrics(fi, cfg);
1071         if (err)
1072                 goto failure;
1073 
1074         if (cfg->fc_mp) {
1075 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1076                 err = fib_get_nhs(fi, cfg->fc_mp, cfg->fc_mp_len, cfg);
1077                 if (err != 0)
1078                         goto failure;
1079                 if (cfg->fc_oif && fi->fib_nh->nh_oif != cfg->fc_oif)
1080                         goto err_inval;
1081                 if (cfg->fc_gw && fi->fib_nh->nh_gw != cfg->fc_gw)
1082                         goto err_inval;
1083 #ifdef CONFIG_IP_ROUTE_CLASSID
1084                 if (cfg->fc_flow && fi->fib_nh->nh_tclassid != cfg->fc_flow)
1085                         goto err_inval;
1086 #endif
1087 #else
1088                 goto err_inval;
1089 #endif
1090         } else {
1091                 struct fib_nh *nh = fi->fib_nh;
1092 
1093                 if (cfg->fc_encap) {
1094                         struct lwtunnel_state *lwtstate;
1095                         struct net_device *dev = NULL;
1096 
1097                         if (cfg->fc_encap_type == LWTUNNEL_ENCAP_NONE)
1098                                 goto err_inval;
1099                         if (cfg->fc_oif)
1100                                 dev = __dev_get_by_index(net, cfg->fc_oif);
1101                         err = lwtunnel_build_state(dev, cfg->fc_encap_type,
1102                                                    cfg->fc_encap, AF_INET, cfg,
1103                                                    &lwtstate);
1104                         if (err)
1105                                 goto failure;
1106 
1107                         nh->nh_lwtstate = lwtstate_get(lwtstate);
1108                 }
1109                 nh->nh_oif = cfg->fc_oif;
1110                 nh->nh_gw = cfg->fc_gw;
1111                 nh->nh_flags = cfg->fc_flags;
1112 #ifdef CONFIG_IP_ROUTE_CLASSID
1113                 nh->nh_tclassid = cfg->fc_flow;
1114                 if (nh->nh_tclassid)
1115                         fi->fib_net->ipv4.fib_num_tclassid_users++;
1116 #endif
1117 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1118                 nh->nh_weight = 1;
1119 #endif
1120         }
1121 
1122         if (fib_props[cfg->fc_type].error) {
1123                 if (cfg->fc_gw || cfg->fc_oif || cfg->fc_mp)
1124                         goto err_inval;
1125                 goto link_it;
1126         } else {
1127                 switch (cfg->fc_type) {
1128                 case RTN_UNICAST:
1129                 case RTN_LOCAL:
1130                 case RTN_BROADCAST:
1131                 case RTN_ANYCAST:
1132                 case RTN_MULTICAST:
1133                         break;
1134                 default:
1135                         goto err_inval;
1136                 }
1137         }
1138 
1139         if (cfg->fc_scope > RT_SCOPE_HOST)
1140                 goto err_inval;
1141 
1142         if (cfg->fc_scope == RT_SCOPE_HOST) {
1143                 struct fib_nh *nh = fi->fib_nh;
1144 
1145                 /* Local address is added. */
1146                 if (nhs != 1 || nh->nh_gw)
1147                         goto err_inval;
1148                 nh->nh_scope = RT_SCOPE_NOWHERE;
1149                 nh->nh_dev = dev_get_by_index(net, fi->fib_nh->nh_oif);
1150                 err = -ENODEV;
1151                 if (!nh->nh_dev)
1152                         goto failure;
1153         } else {
1154                 int linkdown = 0;
1155 
1156                 change_nexthops(fi) {
1157                         err = fib_check_nh(cfg, fi, nexthop_nh);
1158                         if (err != 0)
1159                                 goto failure;
1160                         if (nexthop_nh->nh_flags & RTNH_F_LINKDOWN)
1161                                 linkdown++;
1162                 } endfor_nexthops(fi)
1163                 if (linkdown == fi->fib_nhs)
1164                         fi->fib_flags |= RTNH_F_LINKDOWN;
1165         }
1166 
1167         if (fi->fib_prefsrc && !fib_valid_prefsrc(cfg, fi->fib_prefsrc))
1168                 goto err_inval;
1169 
1170         change_nexthops(fi) {
1171                 fib_info_update_nh_saddr(net, nexthop_nh);
1172                 fib_add_weight(fi, nexthop_nh);
1173         } endfor_nexthops(fi)
1174 
1175         fib_rebalance(fi);
1176 
1177 link_it:
1178         ofi = fib_find_info(fi);
1179         if (ofi) {
1180                 fi->fib_dead = 1;
1181                 free_fib_info(fi);
1182                 ofi->fib_treeref++;
1183                 return ofi;
1184         }
1185 
1186         fi->fib_treeref++;
1187         atomic_inc(&fi->fib_clntref);
1188         spin_lock_bh(&fib_info_lock);
1189         hlist_add_head(&fi->fib_hash,
1190                        &fib_info_hash[fib_info_hashfn(fi)]);
1191         if (fi->fib_prefsrc) {
1192                 struct hlist_head *head;
1193 
1194                 head = &fib_info_laddrhash[fib_laddr_hashfn(fi->fib_prefsrc)];
1195                 hlist_add_head(&fi->fib_lhash, head);
1196         }
1197         change_nexthops(fi) {
1198                 struct hlist_head *head;
1199                 unsigned int hash;
1200 
1201                 if (!nexthop_nh->nh_dev)
1202                         continue;
1203                 hash = fib_devindex_hashfn(nexthop_nh->nh_dev->ifindex);
1204                 head = &fib_info_devhash[hash];
1205                 hlist_add_head(&nexthop_nh->nh_hash, head);
1206         } endfor_nexthops(fi)
1207         spin_unlock_bh(&fib_info_lock);
1208         return fi;
1209 
1210 err_inval:
1211         err = -EINVAL;
1212 
1213 failure:
1214         if (fi) {
1215                 fi->fib_dead = 1;
1216                 free_fib_info(fi);
1217         }
1218 
1219         return ERR_PTR(err);
1220 }
1221 
1222 int fib_dump_info(struct sk_buff *skb, u32 portid, u32 seq, int event,
1223                   u32 tb_id, u8 type, __be32 dst, int dst_len, u8 tos,
1224                   struct fib_info *fi, unsigned int flags)
1225 {
1226         struct nlmsghdr *nlh;
1227         struct rtmsg *rtm;
1228 
1229         nlh = nlmsg_put(skb, portid, seq, event, sizeof(*rtm), flags);
1230         if (!nlh)
1231                 return -EMSGSIZE;
1232 
1233         rtm = nlmsg_data(nlh);
1234         rtm->rtm_family = AF_INET;
1235         rtm->rtm_dst_len = dst_len;
1236         rtm->rtm_src_len = 0;
1237         rtm->rtm_tos = tos;
1238         if (tb_id < 256)
1239                 rtm->rtm_table = tb_id;
1240         else
1241                 rtm->rtm_table = RT_TABLE_COMPAT;
1242         if (nla_put_u32(skb, RTA_TABLE, tb_id))
1243                 goto nla_put_failure;
1244         rtm->rtm_type = type;
1245         rtm->rtm_flags = fi->fib_flags;
1246         rtm->rtm_scope = fi->fib_scope;
1247         rtm->rtm_protocol = fi->fib_protocol;
1248 
1249         if (rtm->rtm_dst_len &&
1250             nla_put_in_addr(skb, RTA_DST, dst))
1251                 goto nla_put_failure;
1252         if (fi->fib_priority &&
1253             nla_put_u32(skb, RTA_PRIORITY, fi->fib_priority))
1254                 goto nla_put_failure;
1255         if (rtnetlink_put_metrics(skb, fi->fib_metrics) < 0)
1256                 goto nla_put_failure;
1257 
1258         if (fi->fib_prefsrc &&
1259             nla_put_in_addr(skb, RTA_PREFSRC, fi->fib_prefsrc))
1260                 goto nla_put_failure;
1261         if (fi->fib_nhs == 1) {
1262                 struct in_device *in_dev;
1263 
1264                 if (fi->fib_nh->nh_gw &&
1265                     nla_put_in_addr(skb, RTA_GATEWAY, fi->fib_nh->nh_gw))
1266                         goto nla_put_failure;
1267                 if (fi->fib_nh->nh_oif &&
1268                     nla_put_u32(skb, RTA_OIF, fi->fib_nh->nh_oif))
1269                         goto nla_put_failure;
1270                 if (fi->fib_nh->nh_flags & RTNH_F_LINKDOWN) {
1271                         in_dev = __in_dev_get_rtnl(fi->fib_nh->nh_dev);
1272                         if (in_dev &&
1273                             IN_DEV_IGNORE_ROUTES_WITH_LINKDOWN(in_dev))
1274                                 rtm->rtm_flags |= RTNH_F_DEAD;
1275                 }
1276 #ifdef CONFIG_IP_ROUTE_CLASSID
1277                 if (fi->fib_nh[0].nh_tclassid &&
1278                     nla_put_u32(skb, RTA_FLOW, fi->fib_nh[0].nh_tclassid))
1279                         goto nla_put_failure;
1280 #endif
1281                 if (fi->fib_nh->nh_lwtstate)
1282                         lwtunnel_fill_encap(skb, fi->fib_nh->nh_lwtstate);
1283         }
1284 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1285         if (fi->fib_nhs > 1) {
1286                 struct rtnexthop *rtnh;
1287                 struct nlattr *mp;
1288 
1289                 mp = nla_nest_start(skb, RTA_MULTIPATH);
1290                 if (!mp)
1291                         goto nla_put_failure;
1292 
1293                 for_nexthops(fi) {
1294                         struct in_device *in_dev;
1295 
1296                         rtnh = nla_reserve_nohdr(skb, sizeof(*rtnh));
1297                         if (!rtnh)
1298                                 goto nla_put_failure;
1299 
1300                         rtnh->rtnh_flags = nh->nh_flags & 0xFF;
1301                         if (nh->nh_flags & RTNH_F_LINKDOWN) {
1302                                 in_dev = __in_dev_get_rtnl(nh->nh_dev);
1303                                 if (in_dev &&
1304                                     IN_DEV_IGNORE_ROUTES_WITH_LINKDOWN(in_dev))
1305                                         rtnh->rtnh_flags |= RTNH_F_DEAD;
1306                         }
1307                         rtnh->rtnh_hops = nh->nh_weight - 1;
1308                         rtnh->rtnh_ifindex = nh->nh_oif;
1309 
1310                         if (nh->nh_gw &&
1311                             nla_put_in_addr(skb, RTA_GATEWAY, nh->nh_gw))
1312                                 goto nla_put_failure;
1313 #ifdef CONFIG_IP_ROUTE_CLASSID
1314                         if (nh->nh_tclassid &&
1315                             nla_put_u32(skb, RTA_FLOW, nh->nh_tclassid))
1316                                 goto nla_put_failure;
1317 #endif
1318                         if (nh->nh_lwtstate)
1319                                 lwtunnel_fill_encap(skb, nh->nh_lwtstate);
1320                         /* length of rtnetlink header + attributes */
1321                         rtnh->rtnh_len = nlmsg_get_pos(skb) - (void *) rtnh;
1322                 } endfor_nexthops(fi);
1323 
1324                 nla_nest_end(skb, mp);
1325         }
1326 #endif
1327         nlmsg_end(skb, nlh);
1328         return 0;
1329 
1330 nla_put_failure:
1331         nlmsg_cancel(skb, nlh);
1332         return -EMSGSIZE;
1333 }
1334 
1335 /*
1336  * Update FIB if:
1337  * - local address disappeared -> we must delete all the entries
1338  *   referring to it.
1339  * - device went down -> we must shutdown all nexthops going via it.
1340  */
1341 int fib_sync_down_addr(struct net_device *dev, __be32 local)
1342 {
1343         int ret = 0;
1344         unsigned int hash = fib_laddr_hashfn(local);
1345         struct hlist_head *head = &fib_info_laddrhash[hash];
1346         struct net *net = dev_net(dev);
1347         int tb_id = l3mdev_fib_table(dev);
1348         struct fib_info *fi;
1349 
1350         if (!fib_info_laddrhash || local == 0)
1351                 return 0;
1352 
1353         hlist_for_each_entry(fi, head, fib_lhash) {
1354                 if (!net_eq(fi->fib_net, net) ||
1355                     fi->fib_tb_id != tb_id)
1356                         continue;
1357                 if (fi->fib_prefsrc == local) {
1358                         fi->fib_flags |= RTNH_F_DEAD;
1359                         ret++;
1360                 }
1361         }
1362         return ret;
1363 }
1364 
1365 /* Event              force Flags           Description
1366  * NETDEV_CHANGE      0     LINKDOWN        Carrier OFF, not for scope host
1367  * NETDEV_DOWN        0     LINKDOWN|DEAD   Link down, not for scope host
1368  * NETDEV_DOWN        1     LINKDOWN|DEAD   Last address removed
1369  * NETDEV_UNREGISTER  1     LINKDOWN|DEAD   Device removed
1370  */
1371 int fib_sync_down_dev(struct net_device *dev, unsigned long event, bool force)
1372 {
1373         int ret = 0;
1374         int scope = RT_SCOPE_NOWHERE;
1375         struct fib_info *prev_fi = NULL;
1376         unsigned int hash = fib_devindex_hashfn(dev->ifindex);
1377         struct hlist_head *head = &fib_info_devhash[hash];
1378         struct fib_nh *nh;
1379 
1380         if (force)
1381                 scope = -1;
1382 
1383         hlist_for_each_entry(nh, head, nh_hash) {
1384                 struct fib_info *fi = nh->nh_parent;
1385                 int dead;
1386 
1387                 BUG_ON(!fi->fib_nhs);
1388                 if (nh->nh_dev != dev || fi == prev_fi)
1389                         continue;
1390                 prev_fi = fi;
1391                 dead = 0;
1392                 change_nexthops(fi) {
1393                         if (nexthop_nh->nh_flags & RTNH_F_DEAD)
1394                                 dead++;
1395                         else if (nexthop_nh->nh_dev == dev &&
1396                                  nexthop_nh->nh_scope != scope) {
1397                                 switch (event) {
1398                                 case NETDEV_DOWN:
1399                                 case NETDEV_UNREGISTER:
1400                                         nexthop_nh->nh_flags |= RTNH_F_DEAD;
1401                                         /* fall through */
1402                                 case NETDEV_CHANGE:
1403                                         nexthop_nh->nh_flags |= RTNH_F_LINKDOWN;
1404                                         break;
1405                                 }
1406                                 dead++;
1407                         }
1408 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1409                         if (event == NETDEV_UNREGISTER &&
1410                             nexthop_nh->nh_dev == dev) {
1411                                 dead = fi->fib_nhs;
1412                                 break;
1413                         }
1414 #endif
1415                 } endfor_nexthops(fi)
1416                 if (dead == fi->fib_nhs) {
1417                         switch (event) {
1418                         case NETDEV_DOWN:
1419                         case NETDEV_UNREGISTER:
1420                                 fi->fib_flags |= RTNH_F_DEAD;
1421                                 /* fall through */
1422                         case NETDEV_CHANGE:
1423                                 fi->fib_flags |= RTNH_F_LINKDOWN;
1424                                 break;
1425                         }
1426                         ret++;
1427                 }
1428 
1429                 fib_rebalance(fi);
1430         }
1431 
1432         return ret;
1433 }
1434 
1435 /* Must be invoked inside of an RCU protected region.  */
1436 void fib_select_default(const struct flowi4 *flp, struct fib_result *res)
1437 {
1438         struct fib_info *fi = NULL, *last_resort = NULL;
1439         struct hlist_head *fa_head = res->fa_head;
1440         struct fib_table *tb = res->table;
1441         u8 slen = 32 - res->prefixlen;
1442         int order = -1, last_idx = -1;
1443         struct fib_alias *fa, *fa1 = NULL;
1444         u32 last_prio = res->fi->fib_priority;
1445         u8 last_tos = 0;
1446 
1447         hlist_for_each_entry_rcu(fa, fa_head, fa_list) {
1448                 struct fib_info *next_fi = fa->fa_info;
1449 
1450                 if (fa->fa_slen != slen)
1451                         continue;
1452                 if (fa->fa_tos && fa->fa_tos != flp->flowi4_tos)
1453                         continue;
1454                 if (fa->tb_id != tb->tb_id)
1455                         continue;
1456                 if (next_fi->fib_priority > last_prio &&
1457                     fa->fa_tos == last_tos) {
1458                         if (last_tos)
1459                                 continue;
1460                         break;
1461                 }
1462                 if (next_fi->fib_flags & RTNH_F_DEAD)
1463                         continue;
1464                 last_tos = fa->fa_tos;
1465                 last_prio = next_fi->fib_priority;
1466 
1467                 if (next_fi->fib_scope != res->scope ||
1468                     fa->fa_type != RTN_UNICAST)
1469                         continue;
1470                 if (!next_fi->fib_nh[0].nh_gw ||
1471                     next_fi->fib_nh[0].nh_scope != RT_SCOPE_LINK)
1472                         continue;
1473 
1474                 fib_alias_accessed(fa);
1475 
1476                 if (!fi) {
1477                         if (next_fi != res->fi)
1478                                 break;
1479                         fa1 = fa;
1480                 } else if (!fib_detect_death(fi, order, &last_resort,
1481                                              &last_idx, fa1->fa_default)) {
1482                         fib_result_assign(res, fi);
1483                         fa1->fa_default = order;
1484                         goto out;
1485                 }
1486                 fi = next_fi;
1487                 order++;
1488         }
1489 
1490         if (order <= 0 || !fi) {
1491                 if (fa1)
1492                         fa1->fa_default = -1;
1493                 goto out;
1494         }
1495 
1496         if (!fib_detect_death(fi, order, &last_resort, &last_idx,
1497                               fa1->fa_default)) {
1498                 fib_result_assign(res, fi);
1499                 fa1->fa_default = order;
1500                 goto out;
1501         }
1502 
1503         if (last_idx >= 0)
1504                 fib_result_assign(res, last_resort);
1505         fa1->fa_default = last_idx;
1506 out:
1507         return;
1508 }
1509 
1510 /*
1511  * Dead device goes up. We wake up dead nexthops.
1512  * It takes sense only on multipath routes.
1513  */
1514 int fib_sync_up(struct net_device *dev, unsigned int nh_flags)
1515 {
1516         struct fib_info *prev_fi;
1517         unsigned int hash;
1518         struct hlist_head *head;
1519         struct fib_nh *nh;
1520         int ret;
1521 
1522         if (!(dev->flags & IFF_UP))
1523                 return 0;
1524 
1525         if (nh_flags & RTNH_F_DEAD) {
1526                 unsigned int flags = dev_get_flags(dev);
1527 
1528                 if (flags & (IFF_RUNNING | IFF_LOWER_UP))
1529                         nh_flags |= RTNH_F_LINKDOWN;
1530         }
1531 
1532         prev_fi = NULL;
1533         hash = fib_devindex_hashfn(dev->ifindex);
1534         head = &fib_info_devhash[hash];
1535         ret = 0;
1536 
1537         hlist_for_each_entry(nh, head, nh_hash) {
1538                 struct fib_info *fi = nh->nh_parent;
1539                 int alive;
1540 
1541                 BUG_ON(!fi->fib_nhs);
1542                 if (nh->nh_dev != dev || fi == prev_fi)
1543                         continue;
1544 
1545                 prev_fi = fi;
1546                 alive = 0;
1547                 change_nexthops(fi) {
1548                         if (!(nexthop_nh->nh_flags & nh_flags)) {
1549                                 alive++;
1550                                 continue;
1551                         }
1552                         if (!nexthop_nh->nh_dev ||
1553                             !(nexthop_nh->nh_dev->flags & IFF_UP))
1554                                 continue;
1555                         if (nexthop_nh->nh_dev != dev ||
1556                             !__in_dev_get_rtnl(dev))
1557                                 continue;
1558                         alive++;
1559                         nexthop_nh->nh_flags &= ~nh_flags;
1560                 } endfor_nexthops(fi)
1561 
1562                 if (alive > 0) {
1563                         fi->fib_flags &= ~nh_flags;
1564                         ret++;
1565                 }
1566 
1567                 fib_rebalance(fi);
1568         }
1569 
1570         return ret;
1571 }
1572 
1573 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1574 static bool fib_good_nh(const struct fib_nh *nh)
1575 {
1576         int state = NUD_REACHABLE;
1577 
1578         if (nh->nh_scope == RT_SCOPE_LINK) {
1579                 struct neighbour *n;
1580 
1581                 rcu_read_lock_bh();
1582 
1583                 n = __ipv4_neigh_lookup_noref(nh->nh_dev, nh->nh_gw);
1584                 if (n)
1585                         state = n->nud_state;
1586 
1587                 rcu_read_unlock_bh();
1588         }
1589 
1590         return !!(state & NUD_VALID);
1591 }
1592 
1593 void fib_select_multipath(struct fib_result *res, int hash)
1594 {
1595         struct fib_info *fi = res->fi;
1596         struct net *net = fi->fib_net;
1597         bool first = false;
1598 
1599         for_nexthops(fi) {
1600                 if (hash > atomic_read(&nh->nh_upper_bound))
1601                         continue;
1602 
1603                 if (!net->ipv4.sysctl_fib_multipath_use_neigh ||
1604                     fib_good_nh(nh)) {
1605                         res->nh_sel = nhsel;
1606                         return;
1607                 }
1608                 if (!first) {
1609                         res->nh_sel = nhsel;
1610                         first = true;
1611                 }
1612         } endfor_nexthops(fi);
1613 }
1614 #endif
1615 
1616 void fib_select_path(struct net *net, struct fib_result *res,
1617                      struct flowi4 *fl4, int mp_hash)
1618 {
1619 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1620         if (res->fi->fib_nhs > 1 && fl4->flowi4_oif == 0) {
1621                 if (mp_hash < 0)
1622                         mp_hash = get_hash_from_flowi4(fl4) >> 1;
1623 
1624                 fib_select_multipath(res, mp_hash);
1625         }
1626         else
1627 #endif
1628         if (!res->prefixlen &&
1629             res->table->tb_num_default > 1 &&
1630             res->type == RTN_UNICAST && !fl4->flowi4_oif)
1631                 fib_select_default(fl4, res);
1632 
1633         if (!fl4->saddr)
1634                 fl4->saddr = FIB_RES_PREFSRC(net, *res);
1635 }
1636 EXPORT_SYMBOL_GPL(fib_select_path);
1637 

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