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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 <linux/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 #include <linux/netlink.h>
 36 
 37 #include <net/arp.h>
 38 #include <net/ip.h>
 39 #include <net/protocol.h>
 40 #include <net/route.h>
 41 #include <net/tcp.h>
 42 #include <net/sock.h>
 43 #include <net/ip_fib.h>
 44 #include <net/netlink.h>
 45 #include <net/nexthop.h>
 46 #include <net/lwtunnel.h>
 47 #include <net/fib_notifier.h>
 48 
 49 #include "fib_lookup.h"
 50 
 51 static DEFINE_SPINLOCK(fib_info_lock);
 52 static struct hlist_head *fib_info_hash;
 53 static struct hlist_head *fib_info_laddrhash;
 54 static unsigned int fib_info_hash_size;
 55 static unsigned int fib_info_cnt;
 56 
 57 #define DEVINDEX_HASHBITS 8
 58 #define DEVINDEX_HASHSIZE (1U << DEVINDEX_HASHBITS)
 59 static struct hlist_head fib_info_devhash[DEVINDEX_HASHSIZE];
 60 
 61 #ifdef CONFIG_IP_ROUTE_MULTIPATH
 62 
 63 #define for_nexthops(fi) {                                              \
 64         int nhsel; const struct fib_nh *nh;                             \
 65         for (nhsel = 0, nh = (fi)->fib_nh;                              \
 66              nhsel < (fi)->fib_nhs;                                     \
 67              nh++, nhsel++)
 68 
 69 #define change_nexthops(fi) {                                           \
 70         int nhsel; struct fib_nh *nexthop_nh;                           \
 71         for (nhsel = 0, nexthop_nh = (struct fib_nh *)((fi)->fib_nh);   \
 72              nhsel < (fi)->fib_nhs;                                     \
 73              nexthop_nh++, nhsel++)
 74 
 75 #else /* CONFIG_IP_ROUTE_MULTIPATH */
 76 
 77 /* Hope, that gcc will optimize it to get rid of dummy loop */
 78 
 79 #define for_nexthops(fi) {                                              \
 80         int nhsel; const struct fib_nh *nh = (fi)->fib_nh;              \
 81         for (nhsel = 0; nhsel < 1; nhsel++)
 82 
 83 #define change_nexthops(fi) {                                           \
 84         int nhsel;                                                      \
 85         struct fib_nh *nexthop_nh = (struct fib_nh *)((fi)->fib_nh);    \
 86         for (nhsel = 0; nhsel < 1; nhsel++)
 87 
 88 #endif /* CONFIG_IP_ROUTE_MULTIPATH */
 89 
 90 #define endfor_nexthops(fi) }
 91 
 92 
 93 const struct fib_prop fib_props[RTN_MAX + 1] = {
 94         [RTN_UNSPEC] = {
 95                 .error  = 0,
 96                 .scope  = RT_SCOPE_NOWHERE,
 97         },
 98         [RTN_UNICAST] = {
 99                 .error  = 0,
100                 .scope  = RT_SCOPE_UNIVERSE,
101         },
102         [RTN_LOCAL] = {
103                 .error  = 0,
104                 .scope  = RT_SCOPE_HOST,
105         },
106         [RTN_BROADCAST] = {
107                 .error  = 0,
108                 .scope  = RT_SCOPE_LINK,
109         },
110         [RTN_ANYCAST] = {
111                 .error  = 0,
112                 .scope  = RT_SCOPE_LINK,
113         },
114         [RTN_MULTICAST] = {
115                 .error  = 0,
116                 .scope  = RT_SCOPE_UNIVERSE,
117         },
118         [RTN_BLACKHOLE] = {
119                 .error  = -EINVAL,
120                 .scope  = RT_SCOPE_UNIVERSE,
121         },
122         [RTN_UNREACHABLE] = {
123                 .error  = -EHOSTUNREACH,
124                 .scope  = RT_SCOPE_UNIVERSE,
125         },
126         [RTN_PROHIBIT] = {
127                 .error  = -EACCES,
128                 .scope  = RT_SCOPE_UNIVERSE,
129         },
130         [RTN_THROW] = {
131                 .error  = -EAGAIN,
132                 .scope  = RT_SCOPE_UNIVERSE,
133         },
134         [RTN_NAT] = {
135                 .error  = -EINVAL,
136                 .scope  = RT_SCOPE_NOWHERE,
137         },
138         [RTN_XRESOLVE] = {
139                 .error  = -EINVAL,
140                 .scope  = RT_SCOPE_NOWHERE,
141         },
142 };
143 
144 static void rt_fibinfo_free(struct rtable __rcu **rtp)
145 {
146         struct rtable *rt = rcu_dereference_protected(*rtp, 1);
147 
148         if (!rt)
149                 return;
150 
151         /* Not even needed : RCU_INIT_POINTER(*rtp, NULL);
152          * because we waited an RCU grace period before calling
153          * free_fib_info_rcu()
154          */
155 
156         dst_dev_put(&rt->dst);
157         dst_release_immediate(&rt->dst);
158 }
159 
160 static void free_nh_exceptions(struct fib_nh *nh)
161 {
162         struct fnhe_hash_bucket *hash;
163         int i;
164 
165         hash = rcu_dereference_protected(nh->nh_exceptions, 1);
166         if (!hash)
167                 return;
168         for (i = 0; i < FNHE_HASH_SIZE; i++) {
169                 struct fib_nh_exception *fnhe;
170 
171                 fnhe = rcu_dereference_protected(hash[i].chain, 1);
172                 while (fnhe) {
173                         struct fib_nh_exception *next;
174                         
175                         next = rcu_dereference_protected(fnhe->fnhe_next, 1);
176 
177                         rt_fibinfo_free(&fnhe->fnhe_rth_input);
178                         rt_fibinfo_free(&fnhe->fnhe_rth_output);
179 
180                         kfree(fnhe);
181 
182                         fnhe = next;
183                 }
184         }
185         kfree(hash);
186 }
187 
188 static void rt_fibinfo_free_cpus(struct rtable __rcu * __percpu *rtp)
189 {
190         int cpu;
191 
192         if (!rtp)
193                 return;
194 
195         for_each_possible_cpu(cpu) {
196                 struct rtable *rt;
197 
198                 rt = rcu_dereference_protected(*per_cpu_ptr(rtp, cpu), 1);
199                 if (rt) {
200                         dst_dev_put(&rt->dst);
201                         dst_release_immediate(&rt->dst);
202                 }
203         }
204         free_percpu(rtp);
205 }
206 
207 /* Release a nexthop info record */
208 static void free_fib_info_rcu(struct rcu_head *head)
209 {
210         struct fib_info *fi = container_of(head, struct fib_info, rcu);
211         struct dst_metrics *m;
212 
213         change_nexthops(fi) {
214                 if (nexthop_nh->nh_dev)
215                         dev_put(nexthop_nh->nh_dev);
216                 lwtstate_put(nexthop_nh->nh_lwtstate);
217                 free_nh_exceptions(nexthop_nh);
218                 rt_fibinfo_free_cpus(nexthop_nh->nh_pcpu_rth_output);
219                 rt_fibinfo_free(&nexthop_nh->nh_rth_input);
220         } endfor_nexthops(fi);
221 
222         m = fi->fib_metrics;
223         if (m != &dst_default_metrics && refcount_dec_and_test(&m->refcnt))
224                 kfree(m);
225         kfree(fi);
226 }
227 
228 void free_fib_info(struct fib_info *fi)
229 {
230         if (fi->fib_dead == 0) {
231                 pr_warn("Freeing alive fib_info %p\n", fi);
232                 return;
233         }
234         fib_info_cnt--;
235 #ifdef CONFIG_IP_ROUTE_CLASSID
236         change_nexthops(fi) {
237                 if (nexthop_nh->nh_tclassid)
238                         fi->fib_net->ipv4.fib_num_tclassid_users--;
239         } endfor_nexthops(fi);
240 #endif
241         call_rcu(&fi->rcu, free_fib_info_rcu);
242 }
243 EXPORT_SYMBOL_GPL(free_fib_info);
244 
245 void fib_release_info(struct fib_info *fi)
246 {
247         spin_lock_bh(&fib_info_lock);
248         if (fi && --fi->fib_treeref == 0) {
249                 hlist_del(&fi->fib_hash);
250                 if (fi->fib_prefsrc)
251                         hlist_del(&fi->fib_lhash);
252                 change_nexthops(fi) {
253                         if (!nexthop_nh->nh_dev)
254                                 continue;
255                         hlist_del(&nexthop_nh->nh_hash);
256                 } endfor_nexthops(fi)
257                 fi->fib_dead = 1;
258                 fib_info_put(fi);
259         }
260         spin_unlock_bh(&fib_info_lock);
261 }
262 
263 static inline int nh_comp(const struct fib_info *fi, const struct fib_info *ofi)
264 {
265         const struct fib_nh *onh = ofi->fib_nh;
266 
267         for_nexthops(fi) {
268                 if (nh->nh_oif != onh->nh_oif ||
269                     nh->nh_gw  != onh->nh_gw ||
270                     nh->nh_scope != onh->nh_scope ||
271 #ifdef CONFIG_IP_ROUTE_MULTIPATH
272                     nh->nh_weight != onh->nh_weight ||
273 #endif
274 #ifdef CONFIG_IP_ROUTE_CLASSID
275                     nh->nh_tclassid != onh->nh_tclassid ||
276 #endif
277                     lwtunnel_cmp_encap(nh->nh_lwtstate, onh->nh_lwtstate) ||
278                     ((nh->nh_flags ^ onh->nh_flags) & ~RTNH_COMPARE_MASK))
279                         return -1;
280                 onh++;
281         } endfor_nexthops(fi);
282         return 0;
283 }
284 
285 static inline unsigned int fib_devindex_hashfn(unsigned int val)
286 {
287         unsigned int mask = DEVINDEX_HASHSIZE - 1;
288 
289         return (val ^
290                 (val >> DEVINDEX_HASHBITS) ^
291                 (val >> (DEVINDEX_HASHBITS * 2))) & mask;
292 }
293 
294 static inline unsigned int fib_info_hashfn(const struct fib_info *fi)
295 {
296         unsigned int mask = (fib_info_hash_size - 1);
297         unsigned int val = fi->fib_nhs;
298 
299         val ^= (fi->fib_protocol << 8) | fi->fib_scope;
300         val ^= (__force u32)fi->fib_prefsrc;
301         val ^= fi->fib_priority;
302         for_nexthops(fi) {
303                 val ^= fib_devindex_hashfn(nh->nh_oif);
304         } endfor_nexthops(fi)
305 
306         return (val ^ (val >> 7) ^ (val >> 12)) & mask;
307 }
308 
309 static struct fib_info *fib_find_info(const struct fib_info *nfi)
310 {
311         struct hlist_head *head;
312         struct fib_info *fi;
313         unsigned int hash;
314 
315         hash = fib_info_hashfn(nfi);
316         head = &fib_info_hash[hash];
317 
318         hlist_for_each_entry(fi, head, fib_hash) {
319                 if (!net_eq(fi->fib_net, nfi->fib_net))
320                         continue;
321                 if (fi->fib_nhs != nfi->fib_nhs)
322                         continue;
323                 if (nfi->fib_protocol == fi->fib_protocol &&
324                     nfi->fib_scope == fi->fib_scope &&
325                     nfi->fib_prefsrc == fi->fib_prefsrc &&
326                     nfi->fib_priority == fi->fib_priority &&
327                     nfi->fib_type == fi->fib_type &&
328                     memcmp(nfi->fib_metrics, fi->fib_metrics,
329                            sizeof(u32) * RTAX_MAX) == 0 &&
330                     !((nfi->fib_flags ^ fi->fib_flags) & ~RTNH_COMPARE_MASK) &&
331                     (nfi->fib_nhs == 0 || nh_comp(fi, nfi) == 0))
332                         return fi;
333         }
334 
335         return NULL;
336 }
337 
338 /* Check, that the gateway is already configured.
339  * Used only by redirect accept routine.
340  */
341 int ip_fib_check_default(__be32 gw, struct net_device *dev)
342 {
343         struct hlist_head *head;
344         struct fib_nh *nh;
345         unsigned int hash;
346 
347         spin_lock(&fib_info_lock);
348 
349         hash = fib_devindex_hashfn(dev->ifindex);
350         head = &fib_info_devhash[hash];
351         hlist_for_each_entry(nh, head, nh_hash) {
352                 if (nh->nh_dev == dev &&
353                     nh->nh_gw == gw &&
354                     !(nh->nh_flags & RTNH_F_DEAD)) {
355                         spin_unlock(&fib_info_lock);
356                         return 0;
357                 }
358         }
359 
360         spin_unlock(&fib_info_lock);
361 
362         return -1;
363 }
364 
365 static inline size_t fib_nlmsg_size(struct fib_info *fi)
366 {
367         size_t payload = NLMSG_ALIGN(sizeof(struct rtmsg))
368                          + nla_total_size(4) /* RTA_TABLE */
369                          + nla_total_size(4) /* RTA_DST */
370                          + nla_total_size(4) /* RTA_PRIORITY */
371                          + nla_total_size(4) /* RTA_PREFSRC */
372                          + nla_total_size(TCP_CA_NAME_MAX); /* RTAX_CC_ALGO */
373 
374         /* space for nested metrics */
375         payload += nla_total_size((RTAX_MAX * nla_total_size(4)));
376 
377         if (fi->fib_nhs) {
378                 size_t nh_encapsize = 0;
379                 /* Also handles the special case fib_nhs == 1 */
380 
381                 /* each nexthop is packed in an attribute */
382                 size_t nhsize = nla_total_size(sizeof(struct rtnexthop));
383 
384                 /* may contain flow and gateway attribute */
385                 nhsize += 2 * nla_total_size(4);
386 
387                 /* grab encap info */
388                 for_nexthops(fi) {
389                         if (nh->nh_lwtstate) {
390                                 /* RTA_ENCAP_TYPE */
391                                 nh_encapsize += lwtunnel_get_encap_size(
392                                                 nh->nh_lwtstate);
393                                 /* RTA_ENCAP */
394                                 nh_encapsize +=  nla_total_size(2);
395                         }
396                 } endfor_nexthops(fi);
397 
398                 /* all nexthops are packed in a nested attribute */
399                 payload += nla_total_size((fi->fib_nhs * nhsize) +
400                                           nh_encapsize);
401 
402         }
403 
404         return payload;
405 }
406 
407 void rtmsg_fib(int event, __be32 key, struct fib_alias *fa,
408                int dst_len, u32 tb_id, const struct nl_info *info,
409                unsigned int nlm_flags)
410 {
411         struct sk_buff *skb;
412         u32 seq = info->nlh ? info->nlh->nlmsg_seq : 0;
413         int err = -ENOBUFS;
414 
415         skb = nlmsg_new(fib_nlmsg_size(fa->fa_info), GFP_KERNEL);
416         if (!skb)
417                 goto errout;
418 
419         err = fib_dump_info(skb, info->portid, seq, event, tb_id,
420                             fa->fa_type, key, dst_len,
421                             fa->fa_tos, fa->fa_info, nlm_flags);
422         if (err < 0) {
423                 /* -EMSGSIZE implies BUG in fib_nlmsg_size() */
424                 WARN_ON(err == -EMSGSIZE);
425                 kfree_skb(skb);
426                 goto errout;
427         }
428         rtnl_notify(skb, info->nl_net, info->portid, RTNLGRP_IPV4_ROUTE,
429                     info->nlh, GFP_KERNEL);
430         return;
431 errout:
432         if (err < 0)
433                 rtnl_set_sk_err(info->nl_net, RTNLGRP_IPV4_ROUTE, err);
434 }
435 
436 static int fib_detect_death(struct fib_info *fi, int order,
437                             struct fib_info **last_resort, int *last_idx,
438                             int dflt)
439 {
440         struct neighbour *n;
441         int state = NUD_NONE;
442 
443         n = neigh_lookup(&arp_tbl, &fi->fib_nh[0].nh_gw, fi->fib_dev);
444         if (n) {
445                 state = n->nud_state;
446                 neigh_release(n);
447         } else {
448                 return 0;
449         }
450         if (state == NUD_REACHABLE)
451                 return 0;
452         if ((state & NUD_VALID) && order != dflt)
453                 return 0;
454         if ((state & NUD_VALID) ||
455             (*last_idx < 0 && order > dflt && state != NUD_INCOMPLETE)) {
456                 *last_resort = fi;
457                 *last_idx = order;
458         }
459         return 1;
460 }
461 
462 #ifdef CONFIG_IP_ROUTE_MULTIPATH
463 
464 static int fib_count_nexthops(struct rtnexthop *rtnh, int remaining,
465                               struct netlink_ext_ack *extack)
466 {
467         int nhs = 0;
468 
469         while (rtnh_ok(rtnh, remaining)) {
470                 nhs++;
471                 rtnh = rtnh_next(rtnh, &remaining);
472         }
473 
474         /* leftover implies invalid nexthop configuration, discard it */
475         if (remaining > 0) {
476                 NL_SET_ERR_MSG(extack,
477                                "Invalid nexthop configuration - extra data after nexthops");
478                 nhs = 0;
479         }
480 
481         return nhs;
482 }
483 
484 static int fib_get_nhs(struct fib_info *fi, struct rtnexthop *rtnh,
485                        int remaining, struct fib_config *cfg,
486                        struct netlink_ext_ack *extack)
487 {
488         int ret;
489 
490         change_nexthops(fi) {
491                 int attrlen;
492 
493                 if (!rtnh_ok(rtnh, remaining)) {
494                         NL_SET_ERR_MSG(extack,
495                                        "Invalid nexthop configuration - extra data after nexthop");
496                         return -EINVAL;
497                 }
498 
499                 if (rtnh->rtnh_flags & (RTNH_F_DEAD | RTNH_F_LINKDOWN)) {
500                         NL_SET_ERR_MSG(extack,
501                                        "Invalid flags for nexthop - can not contain DEAD or LINKDOWN");
502                         return -EINVAL;
503                 }
504 
505                 nexthop_nh->nh_flags =
506                         (cfg->fc_flags & ~0xFF) | rtnh->rtnh_flags;
507                 nexthop_nh->nh_oif = rtnh->rtnh_ifindex;
508                 nexthop_nh->nh_weight = rtnh->rtnh_hops + 1;
509 
510                 attrlen = rtnh_attrlen(rtnh);
511                 if (attrlen > 0) {
512                         struct nlattr *nla, *attrs = rtnh_attrs(rtnh);
513 
514                         nla = nla_find(attrs, attrlen, RTA_GATEWAY);
515                         nexthop_nh->nh_gw = nla ? nla_get_in_addr(nla) : 0;
516 #ifdef CONFIG_IP_ROUTE_CLASSID
517                         nla = nla_find(attrs, attrlen, RTA_FLOW);
518                         nexthop_nh->nh_tclassid = nla ? nla_get_u32(nla) : 0;
519                         if (nexthop_nh->nh_tclassid)
520                                 fi->fib_net->ipv4.fib_num_tclassid_users++;
521 #endif
522                         nla = nla_find(attrs, attrlen, RTA_ENCAP);
523                         if (nla) {
524                                 struct lwtunnel_state *lwtstate;
525                                 struct nlattr *nla_entype;
526 
527                                 nla_entype = nla_find(attrs, attrlen,
528                                                       RTA_ENCAP_TYPE);
529                                 if (!nla_entype) {
530                                         NL_SET_BAD_ATTR(extack, nla);
531                                         NL_SET_ERR_MSG(extack,
532                                                        "Encap type is missing");
533                                         goto err_inval;
534                                 }
535 
536                                 ret = lwtunnel_build_state(nla_get_u16(
537                                                            nla_entype),
538                                                            nla,  AF_INET, cfg,
539                                                            &lwtstate, extack);
540                                 if (ret)
541                                         goto errout;
542                                 nexthop_nh->nh_lwtstate =
543                                         lwtstate_get(lwtstate);
544                         }
545                 }
546 
547                 rtnh = rtnh_next(rtnh, &remaining);
548         } endfor_nexthops(fi);
549 
550         return 0;
551 
552 err_inval:
553         ret = -EINVAL;
554 
555 errout:
556         return ret;
557 }
558 
559 static void fib_rebalance(struct fib_info *fi)
560 {
561         int total;
562         int w;
563         struct in_device *in_dev;
564 
565         if (fi->fib_nhs < 2)
566                 return;
567 
568         total = 0;
569         for_nexthops(fi) {
570                 if (nh->nh_flags & RTNH_F_DEAD)
571                         continue;
572 
573                 in_dev = __in_dev_get_rtnl(nh->nh_dev);
574 
575                 if (in_dev &&
576                     IN_DEV_IGNORE_ROUTES_WITH_LINKDOWN(in_dev) &&
577                     nh->nh_flags & RTNH_F_LINKDOWN)
578                         continue;
579 
580                 total += nh->nh_weight;
581         } endfor_nexthops(fi);
582 
583         w = 0;
584         change_nexthops(fi) {
585                 int upper_bound;
586 
587                 in_dev = __in_dev_get_rtnl(nexthop_nh->nh_dev);
588 
589                 if (nexthop_nh->nh_flags & RTNH_F_DEAD) {
590                         upper_bound = -1;
591                 } else if (in_dev &&
592                            IN_DEV_IGNORE_ROUTES_WITH_LINKDOWN(in_dev) &&
593                            nexthop_nh->nh_flags & RTNH_F_LINKDOWN) {
594                         upper_bound = -1;
595                 } else {
596                         w += nexthop_nh->nh_weight;
597                         upper_bound = DIV_ROUND_CLOSEST_ULL((u64)w << 31,
598                                                             total) - 1;
599                 }
600 
601                 atomic_set(&nexthop_nh->nh_upper_bound, upper_bound);
602         } endfor_nexthops(fi);
603 }
604 #else /* CONFIG_IP_ROUTE_MULTIPATH */
605 
606 #define fib_rebalance(fi) do { } while (0)
607 
608 #endif /* CONFIG_IP_ROUTE_MULTIPATH */
609 
610 static int fib_encap_match(u16 encap_type,
611                            struct nlattr *encap,
612                            const struct fib_nh *nh,
613                            const struct fib_config *cfg,
614                            struct netlink_ext_ack *extack)
615 {
616         struct lwtunnel_state *lwtstate;
617         int ret, result = 0;
618 
619         if (encap_type == LWTUNNEL_ENCAP_NONE)
620                 return 0;
621 
622         ret = lwtunnel_build_state(encap_type, encap, AF_INET,
623                                    cfg, &lwtstate, extack);
624         if (!ret) {
625                 result = lwtunnel_cmp_encap(lwtstate, nh->nh_lwtstate);
626                 lwtstate_free(lwtstate);
627         }
628 
629         return result;
630 }
631 
632 int fib_nh_match(struct fib_config *cfg, struct fib_info *fi,
633                  struct netlink_ext_ack *extack)
634 {
635 #ifdef CONFIG_IP_ROUTE_MULTIPATH
636         struct rtnexthop *rtnh;
637         int remaining;
638 #endif
639 
640         if (cfg->fc_priority && cfg->fc_priority != fi->fib_priority)
641                 return 1;
642 
643         if (cfg->fc_oif || cfg->fc_gw) {
644                 if (cfg->fc_encap) {
645                         if (fib_encap_match(cfg->fc_encap_type, cfg->fc_encap,
646                                             fi->fib_nh, cfg, extack))
647                                 return 1;
648                 }
649 #ifdef CONFIG_IP_ROUTE_CLASSID
650                 if (cfg->fc_flow &&
651                     cfg->fc_flow != fi->fib_nh->nh_tclassid)
652                         return 1;
653 #endif
654                 if ((!cfg->fc_oif || cfg->fc_oif == fi->fib_nh->nh_oif) &&
655                     (!cfg->fc_gw  || cfg->fc_gw == fi->fib_nh->nh_gw))
656                         return 0;
657                 return 1;
658         }
659 
660 #ifdef CONFIG_IP_ROUTE_MULTIPATH
661         if (!cfg->fc_mp)
662                 return 0;
663 
664         rtnh = cfg->fc_mp;
665         remaining = cfg->fc_mp_len;
666 
667         for_nexthops(fi) {
668                 int attrlen;
669 
670                 if (!rtnh_ok(rtnh, remaining))
671                         return -EINVAL;
672 
673                 if (rtnh->rtnh_ifindex && rtnh->rtnh_ifindex != nh->nh_oif)
674                         return 1;
675 
676                 attrlen = rtnh_attrlen(rtnh);
677                 if (attrlen > 0) {
678                         struct nlattr *nla, *attrs = rtnh_attrs(rtnh);
679 
680                         nla = nla_find(attrs, attrlen, RTA_GATEWAY);
681                         if (nla && nla_get_in_addr(nla) != nh->nh_gw)
682                                 return 1;
683 #ifdef CONFIG_IP_ROUTE_CLASSID
684                         nla = nla_find(attrs, attrlen, RTA_FLOW);
685                         if (nla && nla_get_u32(nla) != nh->nh_tclassid)
686                                 return 1;
687 #endif
688                 }
689 
690                 rtnh = rtnh_next(rtnh, &remaining);
691         } endfor_nexthops(fi);
692 #endif
693         return 0;
694 }
695 
696 bool fib_metrics_match(struct fib_config *cfg, struct fib_info *fi)
697 {
698         struct nlattr *nla;
699         int remaining;
700 
701         if (!cfg->fc_mx)
702                 return true;
703 
704         nla_for_each_attr(nla, cfg->fc_mx, cfg->fc_mx_len, remaining) {
705                 int type = nla_type(nla);
706                 u32 fi_val, val;
707 
708                 if (!type)
709                         continue;
710                 if (type > RTAX_MAX)
711                         return false;
712 
713                 if (type == RTAX_CC_ALGO) {
714                         char tmp[TCP_CA_NAME_MAX];
715                         bool ecn_ca = false;
716 
717                         nla_strlcpy(tmp, nla, sizeof(tmp));
718                         val = tcp_ca_get_key_by_name(fi->fib_net, tmp, &ecn_ca);
719                 } else {
720                         val = nla_get_u32(nla);
721                 }
722 
723                 fi_val = fi->fib_metrics->metrics[type - 1];
724                 if (type == RTAX_FEATURES)
725                         fi_val &= ~DST_FEATURE_ECN_CA;
726 
727                 if (fi_val != val)
728                         return false;
729         }
730 
731         return true;
732 }
733 
734 
735 /*
736  * Picture
737  * -------
738  *
739  * Semantics of nexthop is very messy by historical reasons.
740  * We have to take into account, that:
741  * a) gateway can be actually local interface address,
742  *    so that gatewayed route is direct.
743  * b) gateway must be on-link address, possibly
744  *    described not by an ifaddr, but also by a direct route.
745  * c) If both gateway and interface are specified, they should not
746  *    contradict.
747  * d) If we use tunnel routes, gateway could be not on-link.
748  *
749  * Attempt to reconcile all of these (alas, self-contradictory) conditions
750  * results in pretty ugly and hairy code with obscure logic.
751  *
752  * I chose to generalized it instead, so that the size
753  * of code does not increase practically, but it becomes
754  * much more general.
755  * Every prefix is assigned a "scope" value: "host" is local address,
756  * "link" is direct route,
757  * [ ... "site" ... "interior" ... ]
758  * and "universe" is true gateway route with global meaning.
759  *
760  * Every prefix refers to a set of "nexthop"s (gw, oif),
761  * where gw must have narrower scope. This recursion stops
762  * when gw has LOCAL scope or if "nexthop" is declared ONLINK,
763  * which means that gw is forced to be on link.
764  *
765  * Code is still hairy, but now it is apparently logically
766  * consistent and very flexible. F.e. as by-product it allows
767  * to co-exists in peace independent exterior and interior
768  * routing processes.
769  *
770  * Normally it looks as following.
771  *
772  * {universe prefix}  -> (gw, oif) [scope link]
773  *                |
774  *                |-> {link prefix} -> (gw, oif) [scope local]
775  *                                      |
776  *                                      |-> {local prefix} (terminal node)
777  */
778 static int fib_check_nh(struct fib_config *cfg, struct fib_nh *nh,
779                         struct netlink_ext_ack *extack)
780 {
781         int err = 0;
782         struct net *net;
783         struct net_device *dev;
784 
785         net = cfg->fc_nlinfo.nl_net;
786         if (nh->nh_gw) {
787                 struct fib_result res;
788 
789                 if (nh->nh_flags & RTNH_F_ONLINK) {
790                         unsigned int addr_type;
791 
792                         if (cfg->fc_scope >= RT_SCOPE_LINK) {
793                                 NL_SET_ERR_MSG(extack,
794                                                "Nexthop has invalid scope");
795                                 return -EINVAL;
796                         }
797                         dev = __dev_get_by_index(net, nh->nh_oif);
798                         if (!dev)
799                                 return -ENODEV;
800                         if (!(dev->flags & IFF_UP)) {
801                                 NL_SET_ERR_MSG(extack,
802                                                "Nexthop device is not up");
803                                 return -ENETDOWN;
804                         }
805                         addr_type = inet_addr_type_dev_table(net, dev, nh->nh_gw);
806                         if (addr_type != RTN_UNICAST) {
807                                 NL_SET_ERR_MSG(extack,
808                                                "Nexthop has invalid gateway");
809                                 return -EINVAL;
810                         }
811                         if (!netif_carrier_ok(dev))
812                                 nh->nh_flags |= RTNH_F_LINKDOWN;
813                         nh->nh_dev = dev;
814                         dev_hold(dev);
815                         nh->nh_scope = RT_SCOPE_LINK;
816                         return 0;
817                 }
818                 rcu_read_lock();
819                 {
820                         struct fib_table *tbl = NULL;
821                         struct flowi4 fl4 = {
822                                 .daddr = nh->nh_gw,
823                                 .flowi4_scope = cfg->fc_scope + 1,
824                                 .flowi4_oif = nh->nh_oif,
825                                 .flowi4_iif = LOOPBACK_IFINDEX,
826                         };
827 
828                         /* It is not necessary, but requires a bit of thinking */
829                         if (fl4.flowi4_scope < RT_SCOPE_LINK)
830                                 fl4.flowi4_scope = RT_SCOPE_LINK;
831 
832                         if (cfg->fc_table)
833                                 tbl = fib_get_table(net, cfg->fc_table);
834 
835                         if (tbl)
836                                 err = fib_table_lookup(tbl, &fl4, &res,
837                                                        FIB_LOOKUP_IGNORE_LINKSTATE |
838                                                        FIB_LOOKUP_NOREF);
839 
840                         /* on error or if no table given do full lookup. This
841                          * is needed for example when nexthops are in the local
842                          * table rather than the given table
843                          */
844                         if (!tbl || err) {
845                                 err = fib_lookup(net, &fl4, &res,
846                                                  FIB_LOOKUP_IGNORE_LINKSTATE);
847                         }
848 
849                         if (err) {
850                                 NL_SET_ERR_MSG(extack,
851                                                "Nexthop has invalid gateway");
852                                 rcu_read_unlock();
853                                 return err;
854                         }
855                 }
856                 err = -EINVAL;
857                 if (res.type != RTN_UNICAST && res.type != RTN_LOCAL) {
858                         NL_SET_ERR_MSG(extack, "Nexthop has invalid gateway");
859                         goto out;
860                 }
861                 nh->nh_scope = res.scope;
862                 nh->nh_oif = FIB_RES_OIF(res);
863                 nh->nh_dev = dev = FIB_RES_DEV(res);
864                 if (!dev) {
865                         NL_SET_ERR_MSG(extack,
866                                        "No egress device for nexthop gateway");
867                         goto out;
868                 }
869                 dev_hold(dev);
870                 if (!netif_carrier_ok(dev))
871                         nh->nh_flags |= RTNH_F_LINKDOWN;
872                 err = (dev->flags & IFF_UP) ? 0 : -ENETDOWN;
873         } else {
874                 struct in_device *in_dev;
875 
876                 if (nh->nh_flags & (RTNH_F_PERVASIVE | RTNH_F_ONLINK)) {
877                         NL_SET_ERR_MSG(extack,
878                                        "Invalid flags for nexthop - PERVASIVE and ONLINK can not be set");
879                         return -EINVAL;
880                 }
881                 rcu_read_lock();
882                 err = -ENODEV;
883                 in_dev = inetdev_by_index(net, nh->nh_oif);
884                 if (!in_dev)
885                         goto out;
886                 err = -ENETDOWN;
887                 if (!(in_dev->dev->flags & IFF_UP)) {
888                         NL_SET_ERR_MSG(extack, "Device for nexthop is not up");
889                         goto out;
890                 }
891                 nh->nh_dev = in_dev->dev;
892                 dev_hold(nh->nh_dev);
893                 nh->nh_scope = RT_SCOPE_HOST;
894                 if (!netif_carrier_ok(nh->nh_dev))
895                         nh->nh_flags |= RTNH_F_LINKDOWN;
896                 err = 0;
897         }
898 out:
899         rcu_read_unlock();
900         return err;
901 }
902 
903 static inline unsigned int fib_laddr_hashfn(__be32 val)
904 {
905         unsigned int mask = (fib_info_hash_size - 1);
906 
907         return ((__force u32)val ^
908                 ((__force u32)val >> 7) ^
909                 ((__force u32)val >> 14)) & mask;
910 }
911 
912 static struct hlist_head *fib_info_hash_alloc(int bytes)
913 {
914         if (bytes <= PAGE_SIZE)
915                 return kzalloc(bytes, GFP_KERNEL);
916         else
917                 return (struct hlist_head *)
918                         __get_free_pages(GFP_KERNEL | __GFP_ZERO,
919                                          get_order(bytes));
920 }
921 
922 static void fib_info_hash_free(struct hlist_head *hash, int bytes)
923 {
924         if (!hash)
925                 return;
926 
927         if (bytes <= PAGE_SIZE)
928                 kfree(hash);
929         else
930                 free_pages((unsigned long) hash, get_order(bytes));
931 }
932 
933 static void fib_info_hash_move(struct hlist_head *new_info_hash,
934                                struct hlist_head *new_laddrhash,
935                                unsigned int new_size)
936 {
937         struct hlist_head *old_info_hash, *old_laddrhash;
938         unsigned int old_size = fib_info_hash_size;
939         unsigned int i, bytes;
940 
941         spin_lock_bh(&fib_info_lock);
942         old_info_hash = fib_info_hash;
943         old_laddrhash = fib_info_laddrhash;
944         fib_info_hash_size = new_size;
945 
946         for (i = 0; i < old_size; i++) {
947                 struct hlist_head *head = &fib_info_hash[i];
948                 struct hlist_node *n;
949                 struct fib_info *fi;
950 
951                 hlist_for_each_entry_safe(fi, n, head, fib_hash) {
952                         struct hlist_head *dest;
953                         unsigned int new_hash;
954 
955                         new_hash = fib_info_hashfn(fi);
956                         dest = &new_info_hash[new_hash];
957                         hlist_add_head(&fi->fib_hash, dest);
958                 }
959         }
960         fib_info_hash = new_info_hash;
961 
962         for (i = 0; i < old_size; i++) {
963                 struct hlist_head *lhead = &fib_info_laddrhash[i];
964                 struct hlist_node *n;
965                 struct fib_info *fi;
966 
967                 hlist_for_each_entry_safe(fi, n, lhead, fib_lhash) {
968                         struct hlist_head *ldest;
969                         unsigned int new_hash;
970 
971                         new_hash = fib_laddr_hashfn(fi->fib_prefsrc);
972                         ldest = &new_laddrhash[new_hash];
973                         hlist_add_head(&fi->fib_lhash, ldest);
974                 }
975         }
976         fib_info_laddrhash = new_laddrhash;
977 
978         spin_unlock_bh(&fib_info_lock);
979 
980         bytes = old_size * sizeof(struct hlist_head *);
981         fib_info_hash_free(old_info_hash, bytes);
982         fib_info_hash_free(old_laddrhash, bytes);
983 }
984 
985 __be32 fib_info_update_nh_saddr(struct net *net, struct fib_nh *nh)
986 {
987         nh->nh_saddr = inet_select_addr(nh->nh_dev,
988                                         nh->nh_gw,
989                                         nh->nh_parent->fib_scope);
990         nh->nh_saddr_genid = atomic_read(&net->ipv4.dev_addr_genid);
991 
992         return nh->nh_saddr;
993 }
994 
995 static bool fib_valid_prefsrc(struct fib_config *cfg, __be32 fib_prefsrc)
996 {
997         if (cfg->fc_type != RTN_LOCAL || !cfg->fc_dst ||
998             fib_prefsrc != cfg->fc_dst) {
999                 u32 tb_id = cfg->fc_table;
1000                 int rc;
1001 
1002                 if (tb_id == RT_TABLE_MAIN)
1003                         tb_id = RT_TABLE_LOCAL;
1004 
1005                 rc = inet_addr_type_table(cfg->fc_nlinfo.nl_net,
1006                                           fib_prefsrc, tb_id);
1007 
1008                 if (rc != RTN_LOCAL && tb_id != RT_TABLE_LOCAL) {
1009                         rc = inet_addr_type_table(cfg->fc_nlinfo.nl_net,
1010                                                   fib_prefsrc, RT_TABLE_LOCAL);
1011                 }
1012 
1013                 if (rc != RTN_LOCAL)
1014                         return false;
1015         }
1016         return true;
1017 }
1018 
1019 static int
1020 fib_convert_metrics(struct fib_info *fi, const struct fib_config *cfg)
1021 {
1022         bool ecn_ca = false;
1023         struct nlattr *nla;
1024         int remaining;
1025 
1026         if (!cfg->fc_mx)
1027                 return 0;
1028 
1029         nla_for_each_attr(nla, cfg->fc_mx, cfg->fc_mx_len, remaining) {
1030                 int type = nla_type(nla);
1031                 u32 val;
1032 
1033                 if (!type)
1034                         continue;
1035                 if (type > RTAX_MAX)
1036                         return -EINVAL;
1037 
1038                 if (type == RTAX_CC_ALGO) {
1039                         char tmp[TCP_CA_NAME_MAX];
1040 
1041                         nla_strlcpy(tmp, nla, sizeof(tmp));
1042                         val = tcp_ca_get_key_by_name(fi->fib_net, tmp, &ecn_ca);
1043                         if (val == TCP_CA_UNSPEC)
1044                                 return -EINVAL;
1045                 } else {
1046                         val = nla_get_u32(nla);
1047                 }
1048                 if (type == RTAX_ADVMSS && val > 65535 - 40)
1049                         val = 65535 - 40;
1050                 if (type == RTAX_MTU && val > 65535 - 15)
1051                         val = 65535 - 15;
1052                 if (type == RTAX_HOPLIMIT && val > 255)
1053                         val = 255;
1054                 if (type == RTAX_FEATURES && (val & ~RTAX_FEATURE_MASK))
1055                         return -EINVAL;
1056                 fi->fib_metrics->metrics[type - 1] = val;
1057         }
1058 
1059         if (ecn_ca)
1060                 fi->fib_metrics->metrics[RTAX_FEATURES - 1] |= DST_FEATURE_ECN_CA;
1061 
1062         return 0;
1063 }
1064 
1065 struct fib_info *fib_create_info(struct fib_config *cfg,
1066                                  struct netlink_ext_ack *extack)
1067 {
1068         int err;
1069         struct fib_info *fi = NULL;
1070         struct fib_info *ofi;
1071         int nhs = 1;
1072         struct net *net = cfg->fc_nlinfo.nl_net;
1073 
1074         if (cfg->fc_type > RTN_MAX)
1075                 goto err_inval;
1076 
1077         /* Fast check to catch the most weird cases */
1078         if (fib_props[cfg->fc_type].scope > cfg->fc_scope) {
1079                 NL_SET_ERR_MSG(extack, "Invalid scope");
1080                 goto err_inval;
1081         }
1082 
1083         if (cfg->fc_flags & (RTNH_F_DEAD | RTNH_F_LINKDOWN)) {
1084                 NL_SET_ERR_MSG(extack,
1085                                "Invalid rtm_flags - can not contain DEAD or LINKDOWN");
1086                 goto err_inval;
1087         }
1088 
1089 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1090         if (cfg->fc_mp) {
1091                 nhs = fib_count_nexthops(cfg->fc_mp, cfg->fc_mp_len, extack);
1092                 if (nhs == 0)
1093                         goto err_inval;
1094         }
1095 #endif
1096 
1097         err = -ENOBUFS;
1098         if (fib_info_cnt >= fib_info_hash_size) {
1099                 unsigned int new_size = fib_info_hash_size << 1;
1100                 struct hlist_head *new_info_hash;
1101                 struct hlist_head *new_laddrhash;
1102                 unsigned int bytes;
1103 
1104                 if (!new_size)
1105                         new_size = 16;
1106                 bytes = new_size * sizeof(struct hlist_head *);
1107                 new_info_hash = fib_info_hash_alloc(bytes);
1108                 new_laddrhash = fib_info_hash_alloc(bytes);
1109                 if (!new_info_hash || !new_laddrhash) {
1110                         fib_info_hash_free(new_info_hash, bytes);
1111                         fib_info_hash_free(new_laddrhash, bytes);
1112                 } else
1113                         fib_info_hash_move(new_info_hash, new_laddrhash, new_size);
1114 
1115                 if (!fib_info_hash_size)
1116                         goto failure;
1117         }
1118 
1119         fi = kzalloc(sizeof(*fi)+nhs*sizeof(struct fib_nh), GFP_KERNEL);
1120         if (!fi)
1121                 goto failure;
1122         if (cfg->fc_mx) {
1123                 fi->fib_metrics = kzalloc(sizeof(*fi->fib_metrics), GFP_KERNEL);
1124                 if (unlikely(!fi->fib_metrics)) {
1125                         kfree(fi);
1126                         return ERR_PTR(err);
1127                 }
1128                 refcount_set(&fi->fib_metrics->refcnt, 1);
1129         } else {
1130                 fi->fib_metrics = (struct dst_metrics *)&dst_default_metrics;
1131         }
1132         fib_info_cnt++;
1133         fi->fib_net = net;
1134         fi->fib_protocol = cfg->fc_protocol;
1135         fi->fib_scope = cfg->fc_scope;
1136         fi->fib_flags = cfg->fc_flags;
1137         fi->fib_priority = cfg->fc_priority;
1138         fi->fib_prefsrc = cfg->fc_prefsrc;
1139         fi->fib_type = cfg->fc_type;
1140         fi->fib_tb_id = cfg->fc_table;
1141 
1142         fi->fib_nhs = nhs;
1143         change_nexthops(fi) {
1144                 nexthop_nh->nh_parent = fi;
1145                 nexthop_nh->nh_pcpu_rth_output = alloc_percpu(struct rtable __rcu *);
1146                 if (!nexthop_nh->nh_pcpu_rth_output)
1147                         goto failure;
1148         } endfor_nexthops(fi)
1149 
1150         err = fib_convert_metrics(fi, cfg);
1151         if (err)
1152                 goto failure;
1153 
1154         if (cfg->fc_mp) {
1155 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1156                 err = fib_get_nhs(fi, cfg->fc_mp, cfg->fc_mp_len, cfg, extack);
1157                 if (err != 0)
1158                         goto failure;
1159                 if (cfg->fc_oif && fi->fib_nh->nh_oif != cfg->fc_oif) {
1160                         NL_SET_ERR_MSG(extack,
1161                                        "Nexthop device index does not match RTA_OIF");
1162                         goto err_inval;
1163                 }
1164                 if (cfg->fc_gw && fi->fib_nh->nh_gw != cfg->fc_gw) {
1165                         NL_SET_ERR_MSG(extack,
1166                                        "Nexthop gateway does not match RTA_GATEWAY");
1167                         goto err_inval;
1168                 }
1169 #ifdef CONFIG_IP_ROUTE_CLASSID
1170                 if (cfg->fc_flow && fi->fib_nh->nh_tclassid != cfg->fc_flow) {
1171                         NL_SET_ERR_MSG(extack,
1172                                        "Nexthop class id does not match RTA_FLOW");
1173                         goto err_inval;
1174                 }
1175 #endif
1176 #else
1177                 NL_SET_ERR_MSG(extack,
1178                                "Multipath support not enabled in kernel");
1179                 goto err_inval;
1180 #endif
1181         } else {
1182                 struct fib_nh *nh = fi->fib_nh;
1183 
1184                 if (cfg->fc_encap) {
1185                         struct lwtunnel_state *lwtstate;
1186 
1187                         if (cfg->fc_encap_type == LWTUNNEL_ENCAP_NONE) {
1188                                 NL_SET_ERR_MSG(extack,
1189                                                "LWT encap type not specified");
1190                                 goto err_inval;
1191                         }
1192                         err = lwtunnel_build_state(cfg->fc_encap_type,
1193                                                    cfg->fc_encap, AF_INET, cfg,
1194                                                    &lwtstate, extack);
1195                         if (err)
1196                                 goto failure;
1197 
1198                         nh->nh_lwtstate = lwtstate_get(lwtstate);
1199                 }
1200                 nh->nh_oif = cfg->fc_oif;
1201                 nh->nh_gw = cfg->fc_gw;
1202                 nh->nh_flags = cfg->fc_flags;
1203 #ifdef CONFIG_IP_ROUTE_CLASSID
1204                 nh->nh_tclassid = cfg->fc_flow;
1205                 if (nh->nh_tclassid)
1206                         fi->fib_net->ipv4.fib_num_tclassid_users++;
1207 #endif
1208 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1209                 nh->nh_weight = 1;
1210 #endif
1211         }
1212 
1213         if (fib_props[cfg->fc_type].error) {
1214                 if (cfg->fc_gw || cfg->fc_oif || cfg->fc_mp) {
1215                         NL_SET_ERR_MSG(extack,
1216                                        "Gateway, device and multipath can not be specified for this route type");
1217                         goto err_inval;
1218                 }
1219                 goto link_it;
1220         } else {
1221                 switch (cfg->fc_type) {
1222                 case RTN_UNICAST:
1223                 case RTN_LOCAL:
1224                 case RTN_BROADCAST:
1225                 case RTN_ANYCAST:
1226                 case RTN_MULTICAST:
1227                         break;
1228                 default:
1229                         NL_SET_ERR_MSG(extack, "Invalid route type");
1230                         goto err_inval;
1231                 }
1232         }
1233 
1234         if (cfg->fc_scope > RT_SCOPE_HOST) {
1235                 NL_SET_ERR_MSG(extack, "Invalid scope");
1236                 goto err_inval;
1237         }
1238 
1239         if (cfg->fc_scope == RT_SCOPE_HOST) {
1240                 struct fib_nh *nh = fi->fib_nh;
1241 
1242                 /* Local address is added. */
1243                 if (nhs != 1) {
1244                         NL_SET_ERR_MSG(extack,
1245                                        "Route with host scope can not have multiple nexthops");
1246                         goto err_inval;
1247                 }
1248                 if (nh->nh_gw) {
1249                         NL_SET_ERR_MSG(extack,
1250                                        "Route with host scope can not have a gateway");
1251                         goto err_inval;
1252                 }
1253                 nh->nh_scope = RT_SCOPE_NOWHERE;
1254                 nh->nh_dev = dev_get_by_index(net, fi->fib_nh->nh_oif);
1255                 err = -ENODEV;
1256                 if (!nh->nh_dev)
1257                         goto failure;
1258         } else {
1259                 int linkdown = 0;
1260 
1261                 change_nexthops(fi) {
1262                         err = fib_check_nh(cfg, nexthop_nh, extack);
1263                         if (err != 0)
1264                                 goto failure;
1265                         if (nexthop_nh->nh_flags & RTNH_F_LINKDOWN)
1266                                 linkdown++;
1267                 } endfor_nexthops(fi)
1268                 if (linkdown == fi->fib_nhs)
1269                         fi->fib_flags |= RTNH_F_LINKDOWN;
1270         }
1271 
1272         if (fi->fib_prefsrc && !fib_valid_prefsrc(cfg, fi->fib_prefsrc)) {
1273                 NL_SET_ERR_MSG(extack, "Invalid prefsrc address");
1274                 goto err_inval;
1275         }
1276 
1277         change_nexthops(fi) {
1278                 fib_info_update_nh_saddr(net, nexthop_nh);
1279         } endfor_nexthops(fi)
1280 
1281         fib_rebalance(fi);
1282 
1283 link_it:
1284         ofi = fib_find_info(fi);
1285         if (ofi) {
1286                 fi->fib_dead = 1;
1287                 free_fib_info(fi);
1288                 ofi->fib_treeref++;
1289                 return ofi;
1290         }
1291 
1292         fi->fib_treeref++;
1293         refcount_set(&fi->fib_clntref, 1);
1294         spin_lock_bh(&fib_info_lock);
1295         hlist_add_head(&fi->fib_hash,
1296                        &fib_info_hash[fib_info_hashfn(fi)]);
1297         if (fi->fib_prefsrc) {
1298                 struct hlist_head *head;
1299 
1300                 head = &fib_info_laddrhash[fib_laddr_hashfn(fi->fib_prefsrc)];
1301                 hlist_add_head(&fi->fib_lhash, head);
1302         }
1303         change_nexthops(fi) {
1304                 struct hlist_head *head;
1305                 unsigned int hash;
1306 
1307                 if (!nexthop_nh->nh_dev)
1308                         continue;
1309                 hash = fib_devindex_hashfn(nexthop_nh->nh_dev->ifindex);
1310                 head = &fib_info_devhash[hash];
1311                 hlist_add_head(&nexthop_nh->nh_hash, head);
1312         } endfor_nexthops(fi)
1313         spin_unlock_bh(&fib_info_lock);
1314         return fi;
1315 
1316 err_inval:
1317         err = -EINVAL;
1318 
1319 failure:
1320         if (fi) {
1321                 fi->fib_dead = 1;
1322                 free_fib_info(fi);
1323         }
1324 
1325         return ERR_PTR(err);
1326 }
1327 
1328 int fib_dump_info(struct sk_buff *skb, u32 portid, u32 seq, int event,
1329                   u32 tb_id, u8 type, __be32 dst, int dst_len, u8 tos,
1330                   struct fib_info *fi, unsigned int flags)
1331 {
1332         struct nlmsghdr *nlh;
1333         struct rtmsg *rtm;
1334 
1335         nlh = nlmsg_put(skb, portid, seq, event, sizeof(*rtm), flags);
1336         if (!nlh)
1337                 return -EMSGSIZE;
1338 
1339         rtm = nlmsg_data(nlh);
1340         rtm->rtm_family = AF_INET;
1341         rtm->rtm_dst_len = dst_len;
1342         rtm->rtm_src_len = 0;
1343         rtm->rtm_tos = tos;
1344         if (tb_id < 256)
1345                 rtm->rtm_table = tb_id;
1346         else
1347                 rtm->rtm_table = RT_TABLE_COMPAT;
1348         if (nla_put_u32(skb, RTA_TABLE, tb_id))
1349                 goto nla_put_failure;
1350         rtm->rtm_type = type;
1351         rtm->rtm_flags = fi->fib_flags;
1352         rtm->rtm_scope = fi->fib_scope;
1353         rtm->rtm_protocol = fi->fib_protocol;
1354 
1355         if (rtm->rtm_dst_len &&
1356             nla_put_in_addr(skb, RTA_DST, dst))
1357                 goto nla_put_failure;
1358         if (fi->fib_priority &&
1359             nla_put_u32(skb, RTA_PRIORITY, fi->fib_priority))
1360                 goto nla_put_failure;
1361         if (rtnetlink_put_metrics(skb, fi->fib_metrics->metrics) < 0)
1362                 goto nla_put_failure;
1363 
1364         if (fi->fib_prefsrc &&
1365             nla_put_in_addr(skb, RTA_PREFSRC, fi->fib_prefsrc))
1366                 goto nla_put_failure;
1367         if (fi->fib_nhs == 1) {
1368                 if (fi->fib_nh->nh_gw &&
1369                     nla_put_in_addr(skb, RTA_GATEWAY, fi->fib_nh->nh_gw))
1370                         goto nla_put_failure;
1371                 if (fi->fib_nh->nh_oif &&
1372                     nla_put_u32(skb, RTA_OIF, fi->fib_nh->nh_oif))
1373                         goto nla_put_failure;
1374                 if (fi->fib_nh->nh_flags & RTNH_F_LINKDOWN) {
1375                         struct in_device *in_dev;
1376 
1377                         rcu_read_lock();
1378                         in_dev = __in_dev_get_rcu(fi->fib_nh->nh_dev);
1379                         if (in_dev &&
1380                             IN_DEV_IGNORE_ROUTES_WITH_LINKDOWN(in_dev))
1381                                 rtm->rtm_flags |= RTNH_F_DEAD;
1382                         rcu_read_unlock();
1383                 }
1384                 if (fi->fib_nh->nh_flags & RTNH_F_OFFLOAD)
1385                         rtm->rtm_flags |= RTNH_F_OFFLOAD;
1386 #ifdef CONFIG_IP_ROUTE_CLASSID
1387                 if (fi->fib_nh[0].nh_tclassid &&
1388                     nla_put_u32(skb, RTA_FLOW, fi->fib_nh[0].nh_tclassid))
1389                         goto nla_put_failure;
1390 #endif
1391                 if (fi->fib_nh->nh_lwtstate &&
1392                     lwtunnel_fill_encap(skb, fi->fib_nh->nh_lwtstate) < 0)
1393                         goto nla_put_failure;
1394         }
1395 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1396         if (fi->fib_nhs > 1) {
1397                 struct rtnexthop *rtnh;
1398                 struct nlattr *mp;
1399 
1400                 mp = nla_nest_start(skb, RTA_MULTIPATH);
1401                 if (!mp)
1402                         goto nla_put_failure;
1403 
1404                 for_nexthops(fi) {
1405                         rtnh = nla_reserve_nohdr(skb, sizeof(*rtnh));
1406                         if (!rtnh)
1407                                 goto nla_put_failure;
1408 
1409                         rtnh->rtnh_flags = nh->nh_flags & 0xFF;
1410                         if (nh->nh_flags & RTNH_F_LINKDOWN) {
1411                                 struct in_device *in_dev;
1412 
1413                                 rcu_read_lock();
1414                                 in_dev = __in_dev_get_rcu(nh->nh_dev);
1415                                 if (in_dev &&
1416                                     IN_DEV_IGNORE_ROUTES_WITH_LINKDOWN(in_dev))
1417                                         rtnh->rtnh_flags |= RTNH_F_DEAD;
1418                                 rcu_read_unlock();
1419                         }
1420                         rtnh->rtnh_hops = nh->nh_weight - 1;
1421                         rtnh->rtnh_ifindex = nh->nh_oif;
1422 
1423                         if (nh->nh_gw &&
1424                             nla_put_in_addr(skb, RTA_GATEWAY, nh->nh_gw))
1425                                 goto nla_put_failure;
1426 #ifdef CONFIG_IP_ROUTE_CLASSID
1427                         if (nh->nh_tclassid &&
1428                             nla_put_u32(skb, RTA_FLOW, nh->nh_tclassid))
1429                                 goto nla_put_failure;
1430 #endif
1431                         if (nh->nh_lwtstate &&
1432                             lwtunnel_fill_encap(skb, nh->nh_lwtstate) < 0)
1433                                 goto nla_put_failure;
1434 
1435                         /* length of rtnetlink header + attributes */
1436                         rtnh->rtnh_len = nlmsg_get_pos(skb) - (void *) rtnh;
1437                 } endfor_nexthops(fi);
1438 
1439                 nla_nest_end(skb, mp);
1440         }
1441 #endif
1442         nlmsg_end(skb, nlh);
1443         return 0;
1444 
1445 nla_put_failure:
1446         nlmsg_cancel(skb, nlh);
1447         return -EMSGSIZE;
1448 }
1449 
1450 /*
1451  * Update FIB if:
1452  * - local address disappeared -> we must delete all the entries
1453  *   referring to it.
1454  * - device went down -> we must shutdown all nexthops going via it.
1455  */
1456 int fib_sync_down_addr(struct net_device *dev, __be32 local)
1457 {
1458         int ret = 0;
1459         unsigned int hash = fib_laddr_hashfn(local);
1460         struct hlist_head *head = &fib_info_laddrhash[hash];
1461         struct net *net = dev_net(dev);
1462         int tb_id = l3mdev_fib_table(dev);
1463         struct fib_info *fi;
1464 
1465         if (!fib_info_laddrhash || local == 0)
1466                 return 0;
1467 
1468         hlist_for_each_entry(fi, head, fib_lhash) {
1469                 if (!net_eq(fi->fib_net, net) ||
1470                     fi->fib_tb_id != tb_id)
1471                         continue;
1472                 if (fi->fib_prefsrc == local) {
1473                         fi->fib_flags |= RTNH_F_DEAD;
1474                         ret++;
1475                 }
1476         }
1477         return ret;
1478 }
1479 
1480 static int call_fib_nh_notifiers(struct fib_nh *fib_nh,
1481                                  enum fib_event_type event_type)
1482 {
1483         struct in_device *in_dev = __in_dev_get_rtnl(fib_nh->nh_dev);
1484         struct fib_nh_notifier_info info = {
1485                 .fib_nh = fib_nh,
1486         };
1487 
1488         switch (event_type) {
1489         case FIB_EVENT_NH_ADD:
1490                 if (fib_nh->nh_flags & RTNH_F_DEAD)
1491                         break;
1492                 if (IN_DEV_IGNORE_ROUTES_WITH_LINKDOWN(in_dev) &&
1493                     fib_nh->nh_flags & RTNH_F_LINKDOWN)
1494                         break;
1495                 return call_fib4_notifiers(dev_net(fib_nh->nh_dev), event_type,
1496                                            &info.info);
1497         case FIB_EVENT_NH_DEL:
1498                 if ((in_dev && IN_DEV_IGNORE_ROUTES_WITH_LINKDOWN(in_dev) &&
1499                      fib_nh->nh_flags & RTNH_F_LINKDOWN) ||
1500                     (fib_nh->nh_flags & RTNH_F_DEAD))
1501                         return call_fib4_notifiers(dev_net(fib_nh->nh_dev),
1502                                                    event_type, &info.info);
1503         default:
1504                 break;
1505         }
1506 
1507         return NOTIFY_DONE;
1508 }
1509 
1510 /* Event              force Flags           Description
1511  * NETDEV_CHANGE      0     LINKDOWN        Carrier OFF, not for scope host
1512  * NETDEV_DOWN        0     LINKDOWN|DEAD   Link down, not for scope host
1513  * NETDEV_DOWN        1     LINKDOWN|DEAD   Last address removed
1514  * NETDEV_UNREGISTER  1     LINKDOWN|DEAD   Device removed
1515  */
1516 int fib_sync_down_dev(struct net_device *dev, unsigned long event, bool force)
1517 {
1518         int ret = 0;
1519         int scope = RT_SCOPE_NOWHERE;
1520         struct fib_info *prev_fi = NULL;
1521         unsigned int hash = fib_devindex_hashfn(dev->ifindex);
1522         struct hlist_head *head = &fib_info_devhash[hash];
1523         struct fib_nh *nh;
1524 
1525         if (force)
1526                 scope = -1;
1527 
1528         hlist_for_each_entry(nh, head, nh_hash) {
1529                 struct fib_info *fi = nh->nh_parent;
1530                 int dead;
1531 
1532                 BUG_ON(!fi->fib_nhs);
1533                 if (nh->nh_dev != dev || fi == prev_fi)
1534                         continue;
1535                 prev_fi = fi;
1536                 dead = 0;
1537                 change_nexthops(fi) {
1538                         if (nexthop_nh->nh_flags & RTNH_F_DEAD)
1539                                 dead++;
1540                         else if (nexthop_nh->nh_dev == dev &&
1541                                  nexthop_nh->nh_scope != scope) {
1542                                 switch (event) {
1543                                 case NETDEV_DOWN:
1544                                 case NETDEV_UNREGISTER:
1545                                         nexthop_nh->nh_flags |= RTNH_F_DEAD;
1546                                         /* fall through */
1547                                 case NETDEV_CHANGE:
1548                                         nexthop_nh->nh_flags |= RTNH_F_LINKDOWN;
1549                                         break;
1550                                 }
1551                                 call_fib_nh_notifiers(nexthop_nh,
1552                                                       FIB_EVENT_NH_DEL);
1553                                 dead++;
1554                         }
1555 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1556                         if (event == NETDEV_UNREGISTER &&
1557                             nexthop_nh->nh_dev == dev) {
1558                                 dead = fi->fib_nhs;
1559                                 break;
1560                         }
1561 #endif
1562                 } endfor_nexthops(fi)
1563                 if (dead == fi->fib_nhs) {
1564                         switch (event) {
1565                         case NETDEV_DOWN:
1566                         case NETDEV_UNREGISTER:
1567                                 fi->fib_flags |= RTNH_F_DEAD;
1568                                 /* fall through */
1569                         case NETDEV_CHANGE:
1570                                 fi->fib_flags |= RTNH_F_LINKDOWN;
1571                                 break;
1572                         }
1573                         ret++;
1574                 }
1575 
1576                 fib_rebalance(fi);
1577         }
1578 
1579         return ret;
1580 }
1581 
1582 /* Must be invoked inside of an RCU protected region.  */
1583 static void fib_select_default(const struct flowi4 *flp, struct fib_result *res)
1584 {
1585         struct fib_info *fi = NULL, *last_resort = NULL;
1586         struct hlist_head *fa_head = res->fa_head;
1587         struct fib_table *tb = res->table;
1588         u8 slen = 32 - res->prefixlen;
1589         int order = -1, last_idx = -1;
1590         struct fib_alias *fa, *fa1 = NULL;
1591         u32 last_prio = res->fi->fib_priority;
1592         u8 last_tos = 0;
1593 
1594         hlist_for_each_entry_rcu(fa, fa_head, fa_list) {
1595                 struct fib_info *next_fi = fa->fa_info;
1596 
1597                 if (fa->fa_slen != slen)
1598                         continue;
1599                 if (fa->fa_tos && fa->fa_tos != flp->flowi4_tos)
1600                         continue;
1601                 if (fa->tb_id != tb->tb_id)
1602                         continue;
1603                 if (next_fi->fib_priority > last_prio &&
1604                     fa->fa_tos == last_tos) {
1605                         if (last_tos)
1606                                 continue;
1607                         break;
1608                 }
1609                 if (next_fi->fib_flags & RTNH_F_DEAD)
1610                         continue;
1611                 last_tos = fa->fa_tos;
1612                 last_prio = next_fi->fib_priority;
1613 
1614                 if (next_fi->fib_scope != res->scope ||
1615                     fa->fa_type != RTN_UNICAST)
1616                         continue;
1617                 if (!next_fi->fib_nh[0].nh_gw ||
1618                     next_fi->fib_nh[0].nh_scope != RT_SCOPE_LINK)
1619                         continue;
1620 
1621                 fib_alias_accessed(fa);
1622 
1623                 if (!fi) {
1624                         if (next_fi != res->fi)
1625                                 break;
1626                         fa1 = fa;
1627                 } else if (!fib_detect_death(fi, order, &last_resort,
1628                                              &last_idx, fa1->fa_default)) {
1629                         fib_result_assign(res, fi);
1630                         fa1->fa_default = order;
1631                         goto out;
1632                 }
1633                 fi = next_fi;
1634                 order++;
1635         }
1636 
1637         if (order <= 0 || !fi) {
1638                 if (fa1)
1639                         fa1->fa_default = -1;
1640                 goto out;
1641         }
1642 
1643         if (!fib_detect_death(fi, order, &last_resort, &last_idx,
1644                               fa1->fa_default)) {
1645                 fib_result_assign(res, fi);
1646                 fa1->fa_default = order;
1647                 goto out;
1648         }
1649 
1650         if (last_idx >= 0)
1651                 fib_result_assign(res, last_resort);
1652         fa1->fa_default = last_idx;
1653 out:
1654         return;
1655 }
1656 
1657 /*
1658  * Dead device goes up. We wake up dead nexthops.
1659  * It takes sense only on multipath routes.
1660  */
1661 int fib_sync_up(struct net_device *dev, unsigned int nh_flags)
1662 {
1663         struct fib_info *prev_fi;
1664         unsigned int hash;
1665         struct hlist_head *head;
1666         struct fib_nh *nh;
1667         int ret;
1668 
1669         if (!(dev->flags & IFF_UP))
1670                 return 0;
1671 
1672         if (nh_flags & RTNH_F_DEAD) {
1673                 unsigned int flags = dev_get_flags(dev);
1674 
1675                 if (flags & (IFF_RUNNING | IFF_LOWER_UP))
1676                         nh_flags |= RTNH_F_LINKDOWN;
1677         }
1678 
1679         prev_fi = NULL;
1680         hash = fib_devindex_hashfn(dev->ifindex);
1681         head = &fib_info_devhash[hash];
1682         ret = 0;
1683 
1684         hlist_for_each_entry(nh, head, nh_hash) {
1685                 struct fib_info *fi = nh->nh_parent;
1686                 int alive;
1687 
1688                 BUG_ON(!fi->fib_nhs);
1689                 if (nh->nh_dev != dev || fi == prev_fi)
1690                         continue;
1691 
1692                 prev_fi = fi;
1693                 alive = 0;
1694                 change_nexthops(fi) {
1695                         if (!(nexthop_nh->nh_flags & nh_flags)) {
1696                                 alive++;
1697                                 continue;
1698                         }
1699                         if (!nexthop_nh->nh_dev ||
1700                             !(nexthop_nh->nh_dev->flags & IFF_UP))
1701                                 continue;
1702                         if (nexthop_nh->nh_dev != dev ||
1703                             !__in_dev_get_rtnl(dev))
1704                                 continue;
1705                         alive++;
1706                         nexthop_nh->nh_flags &= ~nh_flags;
1707                         call_fib_nh_notifiers(nexthop_nh, FIB_EVENT_NH_ADD);
1708                 } endfor_nexthops(fi)
1709 
1710                 if (alive > 0) {
1711                         fi->fib_flags &= ~nh_flags;
1712                         ret++;
1713                 }
1714 
1715                 fib_rebalance(fi);
1716         }
1717 
1718         return ret;
1719 }
1720 
1721 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1722 static bool fib_good_nh(const struct fib_nh *nh)
1723 {
1724         int state = NUD_REACHABLE;
1725 
1726         if (nh->nh_scope == RT_SCOPE_LINK) {
1727                 struct neighbour *n;
1728 
1729                 rcu_read_lock_bh();
1730 
1731                 n = __ipv4_neigh_lookup_noref(nh->nh_dev,
1732                                               (__force u32)nh->nh_gw);
1733                 if (n)
1734                         state = n->nud_state;
1735 
1736                 rcu_read_unlock_bh();
1737         }
1738 
1739         return !!(state & NUD_VALID);
1740 }
1741 
1742 void fib_select_multipath(struct fib_result *res, int hash)
1743 {
1744         struct fib_info *fi = res->fi;
1745         struct net *net = fi->fib_net;
1746         bool first = false;
1747 
1748         for_nexthops(fi) {
1749                 if (net->ipv4.sysctl_fib_multipath_use_neigh) {
1750                         if (!fib_good_nh(nh))
1751                                 continue;
1752                         if (!first) {
1753                                 res->nh_sel = nhsel;
1754                                 first = true;
1755                         }
1756                 }
1757 
1758                 if (hash > atomic_read(&nh->nh_upper_bound))
1759                         continue;
1760 
1761                 res->nh_sel = nhsel;
1762                 return;
1763         } endfor_nexthops(fi);
1764 }
1765 #endif
1766 
1767 void fib_select_path(struct net *net, struct fib_result *res,
1768                      struct flowi4 *fl4, const struct sk_buff *skb)
1769 {
1770         bool oif_check;
1771 
1772         oif_check = (fl4->flowi4_oif == 0 ||
1773                      fl4->flowi4_flags & FLOWI_FLAG_SKIP_NH_OIF);
1774 
1775 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1776         if (res->fi->fib_nhs > 1 && oif_check) {
1777                 int h = fib_multipath_hash(res->fi, fl4, skb);
1778 
1779                 fib_select_multipath(res, h);
1780         }
1781         else
1782 #endif
1783         if (!res->prefixlen &&
1784             res->table->tb_num_default > 1 &&
1785             res->type == RTN_UNICAST && oif_check)
1786                 fib_select_default(fl4, res);
1787 
1788         if (!fl4->saddr)
1789                 fl4->saddr = FIB_RES_PREFSRC(net, *res);
1790 }
1791 EXPORT_SYMBOL_GPL(fib_select_path);
1792 

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