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Linux/net/ipv4/fib_semantics.c

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  1 // SPDX-License-Identifier: GPL-2.0-or-later
  2 /*
  3  * INET         An implementation of the TCP/IP protocol suite for the LINUX
  4  *              operating system.  INET is implemented using the  BSD Socket
  5  *              interface as the means of communication with the user level.
  6  *
  7  *              IPv4 Forwarding Information Base: semantics.
  8  *
  9  * Authors:     Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
 10  */
 11 
 12 #include <linux/uaccess.h>
 13 #include <linux/bitops.h>
 14 #include <linux/types.h>
 15 #include <linux/kernel.h>
 16 #include <linux/jiffies.h>
 17 #include <linux/mm.h>
 18 #include <linux/string.h>
 19 #include <linux/socket.h>
 20 #include <linux/sockios.h>
 21 #include <linux/errno.h>
 22 #include <linux/in.h>
 23 #include <linux/inet.h>
 24 #include <linux/inetdevice.h>
 25 #include <linux/netdevice.h>
 26 #include <linux/if_arp.h>
 27 #include <linux/proc_fs.h>
 28 #include <linux/skbuff.h>
 29 #include <linux/init.h>
 30 #include <linux/slab.h>
 31 #include <linux/netlink.h>
 32 
 33 #include <net/arp.h>
 34 #include <net/ip.h>
 35 #include <net/protocol.h>
 36 #include <net/route.h>
 37 #include <net/tcp.h>
 38 #include <net/sock.h>
 39 #include <net/ip_fib.h>
 40 #include <net/ip6_fib.h>
 41 #include <net/nexthop.h>
 42 #include <net/netlink.h>
 43 #include <net/rtnh.h>
 44 #include <net/lwtunnel.h>
 45 #include <net/fib_notifier.h>
 46 #include <net/addrconf.h>
 47 
 48 #include "fib_lookup.h"
 49 
 50 static DEFINE_SPINLOCK(fib_info_lock);
 51 static struct hlist_head *fib_info_hash;
 52 static struct hlist_head *fib_info_laddrhash;
 53 static unsigned int fib_info_hash_size;
 54 static unsigned int fib_info_cnt;
 55 
 56 #define DEVINDEX_HASHBITS 8
 57 #define DEVINDEX_HASHSIZE (1U << DEVINDEX_HASHBITS)
 58 static struct hlist_head fib_info_devhash[DEVINDEX_HASHSIZE];
 59 
 60 /* for_nexthops and change_nexthops only used when nexthop object
 61  * is not set in a fib_info. The logic within can reference fib_nh.
 62  */
 63 #ifdef CONFIG_IP_ROUTE_MULTIPATH
 64 
 65 #define for_nexthops(fi) {                                              \
 66         int nhsel; const struct fib_nh *nh;                             \
 67         for (nhsel = 0, nh = (fi)->fib_nh;                              \
 68              nhsel < fib_info_num_path((fi));                           \
 69              nh++, nhsel++)
 70 
 71 #define change_nexthops(fi) {                                           \
 72         int nhsel; struct fib_nh *nexthop_nh;                           \
 73         for (nhsel = 0, nexthop_nh = (struct fib_nh *)((fi)->fib_nh);   \
 74              nhsel < fib_info_num_path((fi));                           \
 75              nexthop_nh++, nhsel++)
 76 
 77 #else /* CONFIG_IP_ROUTE_MULTIPATH */
 78 
 79 /* Hope, that gcc will optimize it to get rid of dummy loop */
 80 
 81 #define for_nexthops(fi) {                                              \
 82         int nhsel; const struct fib_nh *nh = (fi)->fib_nh;              \
 83         for (nhsel = 0; nhsel < 1; nhsel++)
 84 
 85 #define change_nexthops(fi) {                                           \
 86         int nhsel;                                                      \
 87         struct fib_nh *nexthop_nh = (struct fib_nh *)((fi)->fib_nh);    \
 88         for (nhsel = 0; nhsel < 1; nhsel++)
 89 
 90 #endif /* CONFIG_IP_ROUTE_MULTIPATH */
 91 
 92 #define endfor_nexthops(fi) }
 93 
 94 
 95 const struct fib_prop fib_props[RTN_MAX + 1] = {
 96         [RTN_UNSPEC] = {
 97                 .error  = 0,
 98                 .scope  = RT_SCOPE_NOWHERE,
 99         },
100         [RTN_UNICAST] = {
101                 .error  = 0,
102                 .scope  = RT_SCOPE_UNIVERSE,
103         },
104         [RTN_LOCAL] = {
105                 .error  = 0,
106                 .scope  = RT_SCOPE_HOST,
107         },
108         [RTN_BROADCAST] = {
109                 .error  = 0,
110                 .scope  = RT_SCOPE_LINK,
111         },
112         [RTN_ANYCAST] = {
113                 .error  = 0,
114                 .scope  = RT_SCOPE_LINK,
115         },
116         [RTN_MULTICAST] = {
117                 .error  = 0,
118                 .scope  = RT_SCOPE_UNIVERSE,
119         },
120         [RTN_BLACKHOLE] = {
121                 .error  = -EINVAL,
122                 .scope  = RT_SCOPE_UNIVERSE,
123         },
124         [RTN_UNREACHABLE] = {
125                 .error  = -EHOSTUNREACH,
126                 .scope  = RT_SCOPE_UNIVERSE,
127         },
128         [RTN_PROHIBIT] = {
129                 .error  = -EACCES,
130                 .scope  = RT_SCOPE_UNIVERSE,
131         },
132         [RTN_THROW] = {
133                 .error  = -EAGAIN,
134                 .scope  = RT_SCOPE_UNIVERSE,
135         },
136         [RTN_NAT] = {
137                 .error  = -EINVAL,
138                 .scope  = RT_SCOPE_NOWHERE,
139         },
140         [RTN_XRESOLVE] = {
141                 .error  = -EINVAL,
142                 .scope  = RT_SCOPE_NOWHERE,
143         },
144 };
145 
146 static void rt_fibinfo_free(struct rtable __rcu **rtp)
147 {
148         struct rtable *rt = rcu_dereference_protected(*rtp, 1);
149 
150         if (!rt)
151                 return;
152 
153         /* Not even needed : RCU_INIT_POINTER(*rtp, NULL);
154          * because we waited an RCU grace period before calling
155          * free_fib_info_rcu()
156          */
157 
158         dst_dev_put(&rt->dst);
159         dst_release_immediate(&rt->dst);
160 }
161 
162 static void free_nh_exceptions(struct fib_nh_common *nhc)
163 {
164         struct fnhe_hash_bucket *hash;
165         int i;
166 
167         hash = rcu_dereference_protected(nhc->nhc_exceptions, 1);
168         if (!hash)
169                 return;
170         for (i = 0; i < FNHE_HASH_SIZE; i++) {
171                 struct fib_nh_exception *fnhe;
172 
173                 fnhe = rcu_dereference_protected(hash[i].chain, 1);
174                 while (fnhe) {
175                         struct fib_nh_exception *next;
176 
177                         next = rcu_dereference_protected(fnhe->fnhe_next, 1);
178 
179                         rt_fibinfo_free(&fnhe->fnhe_rth_input);
180                         rt_fibinfo_free(&fnhe->fnhe_rth_output);
181 
182                         kfree(fnhe);
183 
184                         fnhe = next;
185                 }
186         }
187         kfree(hash);
188 }
189 
190 static void rt_fibinfo_free_cpus(struct rtable __rcu * __percpu *rtp)
191 {
192         int cpu;
193 
194         if (!rtp)
195                 return;
196 
197         for_each_possible_cpu(cpu) {
198                 struct rtable *rt;
199 
200                 rt = rcu_dereference_protected(*per_cpu_ptr(rtp, cpu), 1);
201                 if (rt) {
202                         dst_dev_put(&rt->dst);
203                         dst_release_immediate(&rt->dst);
204                 }
205         }
206         free_percpu(rtp);
207 }
208 
209 void fib_nh_common_release(struct fib_nh_common *nhc)
210 {
211         if (nhc->nhc_dev)
212                 dev_put(nhc->nhc_dev);
213 
214         lwtstate_put(nhc->nhc_lwtstate);
215         rt_fibinfo_free_cpus(nhc->nhc_pcpu_rth_output);
216         rt_fibinfo_free(&nhc->nhc_rth_input);
217         free_nh_exceptions(nhc);
218 }
219 EXPORT_SYMBOL_GPL(fib_nh_common_release);
220 
221 void fib_nh_release(struct net *net, struct fib_nh *fib_nh)
222 {
223 #ifdef CONFIG_IP_ROUTE_CLASSID
224         if (fib_nh->nh_tclassid)
225                 net->ipv4.fib_num_tclassid_users--;
226 #endif
227         fib_nh_common_release(&fib_nh->nh_common);
228 }
229 
230 /* Release a nexthop info record */
231 static void free_fib_info_rcu(struct rcu_head *head)
232 {
233         struct fib_info *fi = container_of(head, struct fib_info, rcu);
234 
235         if (fi->nh) {
236                 nexthop_put(fi->nh);
237         } else {
238                 change_nexthops(fi) {
239                         fib_nh_release(fi->fib_net, nexthop_nh);
240                 } endfor_nexthops(fi);
241         }
242 
243         ip_fib_metrics_put(fi->fib_metrics);
244 
245         kfree(fi);
246 }
247 
248 void free_fib_info(struct fib_info *fi)
249 {
250         if (fi->fib_dead == 0) {
251                 pr_warn("Freeing alive fib_info %p\n", fi);
252                 return;
253         }
254         fib_info_cnt--;
255 
256         call_rcu(&fi->rcu, free_fib_info_rcu);
257 }
258 EXPORT_SYMBOL_GPL(free_fib_info);
259 
260 void fib_release_info(struct fib_info *fi)
261 {
262         spin_lock_bh(&fib_info_lock);
263         if (fi && --fi->fib_treeref == 0) {
264                 hlist_del(&fi->fib_hash);
265                 if (fi->fib_prefsrc)
266                         hlist_del(&fi->fib_lhash);
267                 if (fi->nh) {
268                         list_del(&fi->nh_list);
269                 } else {
270                         change_nexthops(fi) {
271                                 if (!nexthop_nh->fib_nh_dev)
272                                         continue;
273                                 hlist_del(&nexthop_nh->nh_hash);
274                         } endfor_nexthops(fi)
275                 }
276                 fi->fib_dead = 1;
277                 fib_info_put(fi);
278         }
279         spin_unlock_bh(&fib_info_lock);
280 }
281 
282 static inline int nh_comp(struct fib_info *fi, struct fib_info *ofi)
283 {
284         const struct fib_nh *onh;
285 
286         if (fi->nh || ofi->nh)
287                 return nexthop_cmp(fi->nh, ofi->nh) ? 0 : -1;
288 
289         if (ofi->fib_nhs == 0)
290                 return 0;
291 
292         for_nexthops(fi) {
293                 onh = fib_info_nh(ofi, nhsel);
294 
295                 if (nh->fib_nh_oif != onh->fib_nh_oif ||
296                     nh->fib_nh_gw_family != onh->fib_nh_gw_family ||
297                     nh->fib_nh_scope != onh->fib_nh_scope ||
298 #ifdef CONFIG_IP_ROUTE_MULTIPATH
299                     nh->fib_nh_weight != onh->fib_nh_weight ||
300 #endif
301 #ifdef CONFIG_IP_ROUTE_CLASSID
302                     nh->nh_tclassid != onh->nh_tclassid ||
303 #endif
304                     lwtunnel_cmp_encap(nh->fib_nh_lws, onh->fib_nh_lws) ||
305                     ((nh->fib_nh_flags ^ onh->fib_nh_flags) & ~RTNH_COMPARE_MASK))
306                         return -1;
307 
308                 if (nh->fib_nh_gw_family == AF_INET &&
309                     nh->fib_nh_gw4 != onh->fib_nh_gw4)
310                         return -1;
311 
312                 if (nh->fib_nh_gw_family == AF_INET6 &&
313                     ipv6_addr_cmp(&nh->fib_nh_gw6, &onh->fib_nh_gw6))
314                         return -1;
315         } endfor_nexthops(fi);
316         return 0;
317 }
318 
319 static inline unsigned int fib_devindex_hashfn(unsigned int val)
320 {
321         unsigned int mask = DEVINDEX_HASHSIZE - 1;
322 
323         return (val ^
324                 (val >> DEVINDEX_HASHBITS) ^
325                 (val >> (DEVINDEX_HASHBITS * 2))) & mask;
326 }
327 
328 static unsigned int fib_info_hashfn_1(int init_val, u8 protocol, u8 scope,
329                                       u32 prefsrc, u32 priority)
330 {
331         unsigned int val = init_val;
332 
333         val ^= (protocol << 8) | scope;
334         val ^= prefsrc;
335         val ^= priority;
336 
337         return val;
338 }
339 
340 static unsigned int fib_info_hashfn_result(unsigned int val)
341 {
342         unsigned int mask = (fib_info_hash_size - 1);
343 
344         return (val ^ (val >> 7) ^ (val >> 12)) & mask;
345 }
346 
347 static inline unsigned int fib_info_hashfn(struct fib_info *fi)
348 {
349         unsigned int val;
350 
351         val = fib_info_hashfn_1(fi->fib_nhs, fi->fib_protocol,
352                                 fi->fib_scope, (__force u32)fi->fib_prefsrc,
353                                 fi->fib_priority);
354 
355         if (fi->nh) {
356                 val ^= fib_devindex_hashfn(fi->nh->id);
357         } else {
358                 for_nexthops(fi) {
359                         val ^= fib_devindex_hashfn(nh->fib_nh_oif);
360                 } endfor_nexthops(fi)
361         }
362 
363         return fib_info_hashfn_result(val);
364 }
365 
366 /* no metrics, only nexthop id */
367 static struct fib_info *fib_find_info_nh(struct net *net,
368                                          const struct fib_config *cfg)
369 {
370         struct hlist_head *head;
371         struct fib_info *fi;
372         unsigned int hash;
373 
374         hash = fib_info_hashfn_1(fib_devindex_hashfn(cfg->fc_nh_id),
375                                  cfg->fc_protocol, cfg->fc_scope,
376                                  (__force u32)cfg->fc_prefsrc,
377                                  cfg->fc_priority);
378         hash = fib_info_hashfn_result(hash);
379         head = &fib_info_hash[hash];
380 
381         hlist_for_each_entry(fi, head, fib_hash) {
382                 if (!net_eq(fi->fib_net, net))
383                         continue;
384                 if (!fi->nh || fi->nh->id != cfg->fc_nh_id)
385                         continue;
386                 if (cfg->fc_protocol == fi->fib_protocol &&
387                     cfg->fc_scope == fi->fib_scope &&
388                     cfg->fc_prefsrc == fi->fib_prefsrc &&
389                     cfg->fc_priority == fi->fib_priority &&
390                     cfg->fc_type == fi->fib_type &&
391                     cfg->fc_table == fi->fib_tb_id &&
392                     !((cfg->fc_flags ^ fi->fib_flags) & ~RTNH_COMPARE_MASK))
393                         return fi;
394         }
395 
396         return NULL;
397 }
398 
399 static struct fib_info *fib_find_info(struct fib_info *nfi)
400 {
401         struct hlist_head *head;
402         struct fib_info *fi;
403         unsigned int hash;
404 
405         hash = fib_info_hashfn(nfi);
406         head = &fib_info_hash[hash];
407 
408         hlist_for_each_entry(fi, head, fib_hash) {
409                 if (!net_eq(fi->fib_net, nfi->fib_net))
410                         continue;
411                 if (fi->fib_nhs != nfi->fib_nhs)
412                         continue;
413                 if (nfi->fib_protocol == fi->fib_protocol &&
414                     nfi->fib_scope == fi->fib_scope &&
415                     nfi->fib_prefsrc == fi->fib_prefsrc &&
416                     nfi->fib_priority == fi->fib_priority &&
417                     nfi->fib_type == fi->fib_type &&
418                     memcmp(nfi->fib_metrics, fi->fib_metrics,
419                            sizeof(u32) * RTAX_MAX) == 0 &&
420                     !((nfi->fib_flags ^ fi->fib_flags) & ~RTNH_COMPARE_MASK) &&
421                     nh_comp(fi, nfi) == 0)
422                         return fi;
423         }
424 
425         return NULL;
426 }
427 
428 /* Check, that the gateway is already configured.
429  * Used only by redirect accept routine.
430  */
431 int ip_fib_check_default(__be32 gw, struct net_device *dev)
432 {
433         struct hlist_head *head;
434         struct fib_nh *nh;
435         unsigned int hash;
436 
437         spin_lock(&fib_info_lock);
438 
439         hash = fib_devindex_hashfn(dev->ifindex);
440         head = &fib_info_devhash[hash];
441         hlist_for_each_entry(nh, head, nh_hash) {
442                 if (nh->fib_nh_dev == dev &&
443                     nh->fib_nh_gw4 == gw &&
444                     !(nh->fib_nh_flags & RTNH_F_DEAD)) {
445                         spin_unlock(&fib_info_lock);
446                         return 0;
447                 }
448         }
449 
450         spin_unlock(&fib_info_lock);
451 
452         return -1;
453 }
454 
455 static inline size_t fib_nlmsg_size(struct fib_info *fi)
456 {
457         size_t payload = NLMSG_ALIGN(sizeof(struct rtmsg))
458                          + nla_total_size(4) /* RTA_TABLE */
459                          + nla_total_size(4) /* RTA_DST */
460                          + nla_total_size(4) /* RTA_PRIORITY */
461                          + nla_total_size(4) /* RTA_PREFSRC */
462                          + nla_total_size(TCP_CA_NAME_MAX); /* RTAX_CC_ALGO */
463         unsigned int nhs = fib_info_num_path(fi);
464 
465         /* space for nested metrics */
466         payload += nla_total_size((RTAX_MAX * nla_total_size(4)));
467 
468         if (fi->nh)
469                 payload += nla_total_size(4); /* RTA_NH_ID */
470 
471         if (nhs) {
472                 size_t nh_encapsize = 0;
473                 /* Also handles the special case nhs == 1 */
474 
475                 /* each nexthop is packed in an attribute */
476                 size_t nhsize = nla_total_size(sizeof(struct rtnexthop));
477                 unsigned int i;
478 
479                 /* may contain flow and gateway attribute */
480                 nhsize += 2 * nla_total_size(4);
481 
482                 /* grab encap info */
483                 for (i = 0; i < fib_info_num_path(fi); i++) {
484                         struct fib_nh_common *nhc = fib_info_nhc(fi, i);
485 
486                         if (nhc->nhc_lwtstate) {
487                                 /* RTA_ENCAP_TYPE */
488                                 nh_encapsize += lwtunnel_get_encap_size(
489                                                 nhc->nhc_lwtstate);
490                                 /* RTA_ENCAP */
491                                 nh_encapsize +=  nla_total_size(2);
492                         }
493                 }
494 
495                 /* all nexthops are packed in a nested attribute */
496                 payload += nla_total_size((nhs * nhsize) + nh_encapsize);
497 
498         }
499 
500         return payload;
501 }
502 
503 void rtmsg_fib(int event, __be32 key, struct fib_alias *fa,
504                int dst_len, u32 tb_id, const struct nl_info *info,
505                unsigned int nlm_flags)
506 {
507         struct fib_rt_info fri;
508         struct sk_buff *skb;
509         u32 seq = info->nlh ? info->nlh->nlmsg_seq : 0;
510         int err = -ENOBUFS;
511 
512         skb = nlmsg_new(fib_nlmsg_size(fa->fa_info), GFP_KERNEL);
513         if (!skb)
514                 goto errout;
515 
516         fri.fi = fa->fa_info;
517         fri.tb_id = tb_id;
518         fri.dst = key;
519         fri.dst_len = dst_len;
520         fri.tos = fa->fa_tos;
521         fri.type = fa->fa_type;
522         fri.offload = fa->offload;
523         fri.trap = fa->trap;
524         err = fib_dump_info(skb, info->portid, seq, event, &fri, nlm_flags);
525         if (err < 0) {
526                 /* -EMSGSIZE implies BUG in fib_nlmsg_size() */
527                 WARN_ON(err == -EMSGSIZE);
528                 kfree_skb(skb);
529                 goto errout;
530         }
531         rtnl_notify(skb, info->nl_net, info->portid, RTNLGRP_IPV4_ROUTE,
532                     info->nlh, GFP_KERNEL);
533         return;
534 errout:
535         if (err < 0)
536                 rtnl_set_sk_err(info->nl_net, RTNLGRP_IPV4_ROUTE, err);
537 }
538 
539 static int fib_detect_death(struct fib_info *fi, int order,
540                             struct fib_info **last_resort, int *last_idx,
541                             int dflt)
542 {
543         const struct fib_nh_common *nhc = fib_info_nhc(fi, 0);
544         struct neighbour *n;
545         int state = NUD_NONE;
546 
547         if (likely(nhc->nhc_gw_family == AF_INET))
548                 n = neigh_lookup(&arp_tbl, &nhc->nhc_gw.ipv4, nhc->nhc_dev);
549         else if (nhc->nhc_gw_family == AF_INET6)
550                 n = neigh_lookup(ipv6_stub->nd_tbl, &nhc->nhc_gw.ipv6,
551                                  nhc->nhc_dev);
552         else
553                 n = NULL;
554 
555         if (n) {
556                 state = n->nud_state;
557                 neigh_release(n);
558         } else {
559                 return 0;
560         }
561         if (state == NUD_REACHABLE)
562                 return 0;
563         if ((state & NUD_VALID) && order != dflt)
564                 return 0;
565         if ((state & NUD_VALID) ||
566             (*last_idx < 0 && order > dflt && state != NUD_INCOMPLETE)) {
567                 *last_resort = fi;
568                 *last_idx = order;
569         }
570         return 1;
571 }
572 
573 int fib_nh_common_init(struct net *net, struct fib_nh_common *nhc,
574                        struct nlattr *encap, u16 encap_type,
575                        void *cfg, gfp_t gfp_flags,
576                        struct netlink_ext_ack *extack)
577 {
578         int err;
579 
580         nhc->nhc_pcpu_rth_output = alloc_percpu_gfp(struct rtable __rcu *,
581                                                     gfp_flags);
582         if (!nhc->nhc_pcpu_rth_output)
583                 return -ENOMEM;
584 
585         if (encap) {
586                 struct lwtunnel_state *lwtstate;
587 
588                 if (encap_type == LWTUNNEL_ENCAP_NONE) {
589                         NL_SET_ERR_MSG(extack, "LWT encap type not specified");
590                         err = -EINVAL;
591                         goto lwt_failure;
592                 }
593                 err = lwtunnel_build_state(net, encap_type, encap,
594                                            nhc->nhc_family, cfg, &lwtstate,
595                                            extack);
596                 if (err)
597                         goto lwt_failure;
598 
599                 nhc->nhc_lwtstate = lwtstate_get(lwtstate);
600         }
601 
602         return 0;
603 
604 lwt_failure:
605         rt_fibinfo_free_cpus(nhc->nhc_pcpu_rth_output);
606         nhc->nhc_pcpu_rth_output = NULL;
607         return err;
608 }
609 EXPORT_SYMBOL_GPL(fib_nh_common_init);
610 
611 int fib_nh_init(struct net *net, struct fib_nh *nh,
612                 struct fib_config *cfg, int nh_weight,
613                 struct netlink_ext_ack *extack)
614 {
615         int err;
616 
617         nh->fib_nh_family = AF_INET;
618 
619         err = fib_nh_common_init(net, &nh->nh_common, cfg->fc_encap,
620                                  cfg->fc_encap_type, cfg, GFP_KERNEL, extack);
621         if (err)
622                 return err;
623 
624         nh->fib_nh_oif = cfg->fc_oif;
625         nh->fib_nh_gw_family = cfg->fc_gw_family;
626         if (cfg->fc_gw_family == AF_INET)
627                 nh->fib_nh_gw4 = cfg->fc_gw4;
628         else if (cfg->fc_gw_family == AF_INET6)
629                 nh->fib_nh_gw6 = cfg->fc_gw6;
630 
631         nh->fib_nh_flags = cfg->fc_flags;
632 
633 #ifdef CONFIG_IP_ROUTE_CLASSID
634         nh->nh_tclassid = cfg->fc_flow;
635         if (nh->nh_tclassid)
636                 net->ipv4.fib_num_tclassid_users++;
637 #endif
638 #ifdef CONFIG_IP_ROUTE_MULTIPATH
639         nh->fib_nh_weight = nh_weight;
640 #endif
641         return 0;
642 }
643 
644 #ifdef CONFIG_IP_ROUTE_MULTIPATH
645 
646 static int fib_count_nexthops(struct rtnexthop *rtnh, int remaining,
647                               struct netlink_ext_ack *extack)
648 {
649         int nhs = 0;
650 
651         while (rtnh_ok(rtnh, remaining)) {
652                 nhs++;
653                 rtnh = rtnh_next(rtnh, &remaining);
654         }
655 
656         /* leftover implies invalid nexthop configuration, discard it */
657         if (remaining > 0) {
658                 NL_SET_ERR_MSG(extack,
659                                "Invalid nexthop configuration - extra data after nexthops");
660                 nhs = 0;
661         }
662 
663         return nhs;
664 }
665 
666 /* only called when fib_nh is integrated into fib_info */
667 static int fib_get_nhs(struct fib_info *fi, struct rtnexthop *rtnh,
668                        int remaining, struct fib_config *cfg,
669                        struct netlink_ext_ack *extack)
670 {
671         struct net *net = fi->fib_net;
672         struct fib_config fib_cfg;
673         struct fib_nh *nh;
674         int ret;
675 
676         change_nexthops(fi) {
677                 int attrlen;
678 
679                 memset(&fib_cfg, 0, sizeof(fib_cfg));
680 
681                 if (!rtnh_ok(rtnh, remaining)) {
682                         NL_SET_ERR_MSG(extack,
683                                        "Invalid nexthop configuration - extra data after nexthop");
684                         return -EINVAL;
685                 }
686 
687                 if (rtnh->rtnh_flags & (RTNH_F_DEAD | RTNH_F_LINKDOWN)) {
688                         NL_SET_ERR_MSG(extack,
689                                        "Invalid flags for nexthop - can not contain DEAD or LINKDOWN");
690                         return -EINVAL;
691                 }
692 
693                 fib_cfg.fc_flags = (cfg->fc_flags & ~0xFF) | rtnh->rtnh_flags;
694                 fib_cfg.fc_oif = rtnh->rtnh_ifindex;
695 
696                 attrlen = rtnh_attrlen(rtnh);
697                 if (attrlen > 0) {
698                         struct nlattr *nla, *nlav, *attrs = rtnh_attrs(rtnh);
699 
700                         nla = nla_find(attrs, attrlen, RTA_GATEWAY);
701                         nlav = nla_find(attrs, attrlen, RTA_VIA);
702                         if (nla && nlav) {
703                                 NL_SET_ERR_MSG(extack,
704                                                "Nexthop configuration can not contain both GATEWAY and VIA");
705                                 return -EINVAL;
706                         }
707                         if (nla) {
708                                 fib_cfg.fc_gw4 = nla_get_in_addr(nla);
709                                 if (fib_cfg.fc_gw4)
710                                         fib_cfg.fc_gw_family = AF_INET;
711                         } else if (nlav) {
712                                 ret = fib_gw_from_via(&fib_cfg, nlav, extack);
713                                 if (ret)
714                                         goto errout;
715                         }
716 
717                         nla = nla_find(attrs, attrlen, RTA_FLOW);
718                         if (nla)
719                                 fib_cfg.fc_flow = nla_get_u32(nla);
720 
721                         fib_cfg.fc_encap = nla_find(attrs, attrlen, RTA_ENCAP);
722                         nla = nla_find(attrs, attrlen, RTA_ENCAP_TYPE);
723                         if (nla)
724                                 fib_cfg.fc_encap_type = nla_get_u16(nla);
725                 }
726 
727                 ret = fib_nh_init(net, nexthop_nh, &fib_cfg,
728                                   rtnh->rtnh_hops + 1, extack);
729                 if (ret)
730                         goto errout;
731 
732                 rtnh = rtnh_next(rtnh, &remaining);
733         } endfor_nexthops(fi);
734 
735         ret = -EINVAL;
736         nh = fib_info_nh(fi, 0);
737         if (cfg->fc_oif && nh->fib_nh_oif != cfg->fc_oif) {
738                 NL_SET_ERR_MSG(extack,
739                                "Nexthop device index does not match RTA_OIF");
740                 goto errout;
741         }
742         if (cfg->fc_gw_family) {
743                 if (cfg->fc_gw_family != nh->fib_nh_gw_family ||
744                     (cfg->fc_gw_family == AF_INET &&
745                      nh->fib_nh_gw4 != cfg->fc_gw4) ||
746                     (cfg->fc_gw_family == AF_INET6 &&
747                      ipv6_addr_cmp(&nh->fib_nh_gw6, &cfg->fc_gw6))) {
748                         NL_SET_ERR_MSG(extack,
749                                        "Nexthop gateway does not match RTA_GATEWAY or RTA_VIA");
750                         goto errout;
751                 }
752         }
753 #ifdef CONFIG_IP_ROUTE_CLASSID
754         if (cfg->fc_flow && nh->nh_tclassid != cfg->fc_flow) {
755                 NL_SET_ERR_MSG(extack,
756                                "Nexthop class id does not match RTA_FLOW");
757                 goto errout;
758         }
759 #endif
760         ret = 0;
761 errout:
762         return ret;
763 }
764 
765 /* only called when fib_nh is integrated into fib_info */
766 static void fib_rebalance(struct fib_info *fi)
767 {
768         int total;
769         int w;
770 
771         if (fib_info_num_path(fi) < 2)
772                 return;
773 
774         total = 0;
775         for_nexthops(fi) {
776                 if (nh->fib_nh_flags & RTNH_F_DEAD)
777                         continue;
778 
779                 if (ip_ignore_linkdown(nh->fib_nh_dev) &&
780                     nh->fib_nh_flags & RTNH_F_LINKDOWN)
781                         continue;
782 
783                 total += nh->fib_nh_weight;
784         } endfor_nexthops(fi);
785 
786         w = 0;
787         change_nexthops(fi) {
788                 int upper_bound;
789 
790                 if (nexthop_nh->fib_nh_flags & RTNH_F_DEAD) {
791                         upper_bound = -1;
792                 } else if (ip_ignore_linkdown(nexthop_nh->fib_nh_dev) &&
793                            nexthop_nh->fib_nh_flags & RTNH_F_LINKDOWN) {
794                         upper_bound = -1;
795                 } else {
796                         w += nexthop_nh->fib_nh_weight;
797                         upper_bound = DIV_ROUND_CLOSEST_ULL((u64)w << 31,
798                                                             total) - 1;
799                 }
800 
801                 atomic_set(&nexthop_nh->fib_nh_upper_bound, upper_bound);
802         } endfor_nexthops(fi);
803 }
804 #else /* CONFIG_IP_ROUTE_MULTIPATH */
805 
806 static int fib_get_nhs(struct fib_info *fi, struct rtnexthop *rtnh,
807                        int remaining, struct fib_config *cfg,
808                        struct netlink_ext_ack *extack)
809 {
810         NL_SET_ERR_MSG(extack, "Multipath support not enabled in kernel");
811 
812         return -EINVAL;
813 }
814 
815 #define fib_rebalance(fi) do { } while (0)
816 
817 #endif /* CONFIG_IP_ROUTE_MULTIPATH */
818 
819 static int fib_encap_match(struct net *net, u16 encap_type,
820                            struct nlattr *encap,
821                            const struct fib_nh *nh,
822                            const struct fib_config *cfg,
823                            struct netlink_ext_ack *extack)
824 {
825         struct lwtunnel_state *lwtstate;
826         int ret, result = 0;
827 
828         if (encap_type == LWTUNNEL_ENCAP_NONE)
829                 return 0;
830 
831         ret = lwtunnel_build_state(net, encap_type, encap, AF_INET,
832                                    cfg, &lwtstate, extack);
833         if (!ret) {
834                 result = lwtunnel_cmp_encap(lwtstate, nh->fib_nh_lws);
835                 lwtstate_free(lwtstate);
836         }
837 
838         return result;
839 }
840 
841 int fib_nh_match(struct net *net, struct fib_config *cfg, struct fib_info *fi,
842                  struct netlink_ext_ack *extack)
843 {
844 #ifdef CONFIG_IP_ROUTE_MULTIPATH
845         struct rtnexthop *rtnh;
846         int remaining;
847 #endif
848 
849         if (cfg->fc_priority && cfg->fc_priority != fi->fib_priority)
850                 return 1;
851 
852         if (cfg->fc_nh_id) {
853                 if (fi->nh && cfg->fc_nh_id == fi->nh->id)
854                         return 0;
855                 return 1;
856         }
857 
858         if (cfg->fc_oif || cfg->fc_gw_family) {
859                 struct fib_nh *nh = fib_info_nh(fi, 0);
860 
861                 if (cfg->fc_encap) {
862                         if (fib_encap_match(net, cfg->fc_encap_type,
863                                             cfg->fc_encap, nh, cfg, extack))
864                                 return 1;
865                 }
866 #ifdef CONFIG_IP_ROUTE_CLASSID
867                 if (cfg->fc_flow &&
868                     cfg->fc_flow != nh->nh_tclassid)
869                         return 1;
870 #endif
871                 if ((cfg->fc_oif && cfg->fc_oif != nh->fib_nh_oif) ||
872                     (cfg->fc_gw_family &&
873                      cfg->fc_gw_family != nh->fib_nh_gw_family))
874                         return 1;
875 
876                 if (cfg->fc_gw_family == AF_INET &&
877                     cfg->fc_gw4 != nh->fib_nh_gw4)
878                         return 1;
879 
880                 if (cfg->fc_gw_family == AF_INET6 &&
881                     ipv6_addr_cmp(&cfg->fc_gw6, &nh->fib_nh_gw6))
882                         return 1;
883 
884                 return 0;
885         }
886 
887 #ifdef CONFIG_IP_ROUTE_MULTIPATH
888         if (!cfg->fc_mp)
889                 return 0;
890 
891         rtnh = cfg->fc_mp;
892         remaining = cfg->fc_mp_len;
893 
894         for_nexthops(fi) {
895                 int attrlen;
896 
897                 if (!rtnh_ok(rtnh, remaining))
898                         return -EINVAL;
899 
900                 if (rtnh->rtnh_ifindex && rtnh->rtnh_ifindex != nh->fib_nh_oif)
901                         return 1;
902 
903                 attrlen = rtnh_attrlen(rtnh);
904                 if (attrlen > 0) {
905                         struct nlattr *nla, *nlav, *attrs = rtnh_attrs(rtnh);
906 
907                         nla = nla_find(attrs, attrlen, RTA_GATEWAY);
908                         nlav = nla_find(attrs, attrlen, RTA_VIA);
909                         if (nla && nlav) {
910                                 NL_SET_ERR_MSG(extack,
911                                                "Nexthop configuration can not contain both GATEWAY and VIA");
912                                 return -EINVAL;
913                         }
914 
915                         if (nla) {
916                                 if (nh->fib_nh_gw_family != AF_INET ||
917                                     nla_get_in_addr(nla) != nh->fib_nh_gw4)
918                                         return 1;
919                         } else if (nlav) {
920                                 struct fib_config cfg2;
921                                 int err;
922 
923                                 err = fib_gw_from_via(&cfg2, nlav, extack);
924                                 if (err)
925                                         return err;
926 
927                                 switch (nh->fib_nh_gw_family) {
928                                 case AF_INET:
929                                         if (cfg2.fc_gw_family != AF_INET ||
930                                             cfg2.fc_gw4 != nh->fib_nh_gw4)
931                                                 return 1;
932                                         break;
933                                 case AF_INET6:
934                                         if (cfg2.fc_gw_family != AF_INET6 ||
935                                             ipv6_addr_cmp(&cfg2.fc_gw6,
936                                                           &nh->fib_nh_gw6))
937                                                 return 1;
938                                         break;
939                                 }
940                         }
941 
942 #ifdef CONFIG_IP_ROUTE_CLASSID
943                         nla = nla_find(attrs, attrlen, RTA_FLOW);
944                         if (nla && nla_get_u32(nla) != nh->nh_tclassid)
945                                 return 1;
946 #endif
947                 }
948 
949                 rtnh = rtnh_next(rtnh, &remaining);
950         } endfor_nexthops(fi);
951 #endif
952         return 0;
953 }
954 
955 bool fib_metrics_match(struct fib_config *cfg, struct fib_info *fi)
956 {
957         struct nlattr *nla;
958         int remaining;
959 
960         if (!cfg->fc_mx)
961                 return true;
962 
963         nla_for_each_attr(nla, cfg->fc_mx, cfg->fc_mx_len, remaining) {
964                 int type = nla_type(nla);
965                 u32 fi_val, val;
966 
967                 if (!type)
968                         continue;
969                 if (type > RTAX_MAX)
970                         return false;
971 
972                 if (type == RTAX_CC_ALGO) {
973                         char tmp[TCP_CA_NAME_MAX];
974                         bool ecn_ca = false;
975 
976                         nla_strlcpy(tmp, nla, sizeof(tmp));
977                         val = tcp_ca_get_key_by_name(fi->fib_net, tmp, &ecn_ca);
978                 } else {
979                         if (nla_len(nla) != sizeof(u32))
980                                 return false;
981                         val = nla_get_u32(nla);
982                 }
983 
984                 fi_val = fi->fib_metrics->metrics[type - 1];
985                 if (type == RTAX_FEATURES)
986                         fi_val &= ~DST_FEATURE_ECN_CA;
987 
988                 if (fi_val != val)
989                         return false;
990         }
991 
992         return true;
993 }
994 
995 static int fib_check_nh_v6_gw(struct net *net, struct fib_nh *nh,
996                               u32 table, struct netlink_ext_ack *extack)
997 {
998         struct fib6_config cfg = {
999                 .fc_table = table,
1000                 .fc_flags = nh->fib_nh_flags | RTF_GATEWAY,
1001                 .fc_ifindex = nh->fib_nh_oif,
1002                 .fc_gateway = nh->fib_nh_gw6,
1003         };
1004         struct fib6_nh fib6_nh = {};
1005         int err;
1006 
1007         err = ipv6_stub->fib6_nh_init(net, &fib6_nh, &cfg, GFP_KERNEL, extack);
1008         if (!err) {
1009                 nh->fib_nh_dev = fib6_nh.fib_nh_dev;
1010                 dev_hold(nh->fib_nh_dev);
1011                 nh->fib_nh_oif = nh->fib_nh_dev->ifindex;
1012                 nh->fib_nh_scope = RT_SCOPE_LINK;
1013 
1014                 ipv6_stub->fib6_nh_release(&fib6_nh);
1015         }
1016 
1017         return err;
1018 }
1019 
1020 /*
1021  * Picture
1022  * -------
1023  *
1024  * Semantics of nexthop is very messy by historical reasons.
1025  * We have to take into account, that:
1026  * a) gateway can be actually local interface address,
1027  *    so that gatewayed route is direct.
1028  * b) gateway must be on-link address, possibly
1029  *    described not by an ifaddr, but also by a direct route.
1030  * c) If both gateway and interface are specified, they should not
1031  *    contradict.
1032  * d) If we use tunnel routes, gateway could be not on-link.
1033  *
1034  * Attempt to reconcile all of these (alas, self-contradictory) conditions
1035  * results in pretty ugly and hairy code with obscure logic.
1036  *
1037  * I chose to generalized it instead, so that the size
1038  * of code does not increase practically, but it becomes
1039  * much more general.
1040  * Every prefix is assigned a "scope" value: "host" is local address,
1041  * "link" is direct route,
1042  * [ ... "site" ... "interior" ... ]
1043  * and "universe" is true gateway route with global meaning.
1044  *
1045  * Every prefix refers to a set of "nexthop"s (gw, oif),
1046  * where gw must have narrower scope. This recursion stops
1047  * when gw has LOCAL scope or if "nexthop" is declared ONLINK,
1048  * which means that gw is forced to be on link.
1049  *
1050  * Code is still hairy, but now it is apparently logically
1051  * consistent and very flexible. F.e. as by-product it allows
1052  * to co-exists in peace independent exterior and interior
1053  * routing processes.
1054  *
1055  * Normally it looks as following.
1056  *
1057  * {universe prefix}  -> (gw, oif) [scope link]
1058  *                |
1059  *                |-> {link prefix} -> (gw, oif) [scope local]
1060  *                                      |
1061  *                                      |-> {local prefix} (terminal node)
1062  */
1063 static int fib_check_nh_v4_gw(struct net *net, struct fib_nh *nh, u32 table,
1064                               u8 scope, struct netlink_ext_ack *extack)
1065 {
1066         struct net_device *dev;
1067         struct fib_result res;
1068         int err = 0;
1069 
1070         if (nh->fib_nh_flags & RTNH_F_ONLINK) {
1071                 unsigned int addr_type;
1072 
1073                 if (scope >= RT_SCOPE_LINK) {
1074                         NL_SET_ERR_MSG(extack, "Nexthop has invalid scope");
1075                         return -EINVAL;
1076                 }
1077                 dev = __dev_get_by_index(net, nh->fib_nh_oif);
1078                 if (!dev) {
1079                         NL_SET_ERR_MSG(extack, "Nexthop device required for onlink");
1080                         return -ENODEV;
1081                 }
1082                 if (!(dev->flags & IFF_UP)) {
1083                         NL_SET_ERR_MSG(extack, "Nexthop device is not up");
1084                         return -ENETDOWN;
1085                 }
1086                 addr_type = inet_addr_type_dev_table(net, dev, nh->fib_nh_gw4);
1087                 if (addr_type != RTN_UNICAST) {
1088                         NL_SET_ERR_MSG(extack, "Nexthop has invalid gateway");
1089                         return -EINVAL;
1090                 }
1091                 if (!netif_carrier_ok(dev))
1092                         nh->fib_nh_flags |= RTNH_F_LINKDOWN;
1093                 nh->fib_nh_dev = dev;
1094                 dev_hold(dev);
1095                 nh->fib_nh_scope = RT_SCOPE_LINK;
1096                 return 0;
1097         }
1098         rcu_read_lock();
1099         {
1100                 struct fib_table *tbl = NULL;
1101                 struct flowi4 fl4 = {
1102                         .daddr = nh->fib_nh_gw4,
1103                         .flowi4_scope = scope + 1,
1104                         .flowi4_oif = nh->fib_nh_oif,
1105                         .flowi4_iif = LOOPBACK_IFINDEX,
1106                 };
1107 
1108                 /* It is not necessary, but requires a bit of thinking */
1109                 if (fl4.flowi4_scope < RT_SCOPE_LINK)
1110                         fl4.flowi4_scope = RT_SCOPE_LINK;
1111 
1112                 if (table && table != RT_TABLE_MAIN)
1113                         tbl = fib_get_table(net, table);
1114 
1115                 if (tbl)
1116                         err = fib_table_lookup(tbl, &fl4, &res,
1117                                                FIB_LOOKUP_IGNORE_LINKSTATE |
1118                                                FIB_LOOKUP_NOREF);
1119 
1120                 /* on error or if no table given do full lookup. This
1121                  * is needed for example when nexthops are in the local
1122                  * table rather than the given table
1123                  */
1124                 if (!tbl || err) {
1125                         err = fib_lookup(net, &fl4, &res,
1126                                          FIB_LOOKUP_IGNORE_LINKSTATE);
1127                 }
1128 
1129                 if (err) {
1130                         NL_SET_ERR_MSG(extack, "Nexthop has invalid gateway");
1131                         goto out;
1132                 }
1133         }
1134 
1135         err = -EINVAL;
1136         if (res.type != RTN_UNICAST && res.type != RTN_LOCAL) {
1137                 NL_SET_ERR_MSG(extack, "Nexthop has invalid gateway");
1138                 goto out;
1139         }
1140         nh->fib_nh_scope = res.scope;
1141         nh->fib_nh_oif = FIB_RES_OIF(res);
1142         nh->fib_nh_dev = dev = FIB_RES_DEV(res);
1143         if (!dev) {
1144                 NL_SET_ERR_MSG(extack,
1145                                "No egress device for nexthop gateway");
1146                 goto out;
1147         }
1148         dev_hold(dev);
1149         if (!netif_carrier_ok(dev))
1150                 nh->fib_nh_flags |= RTNH_F_LINKDOWN;
1151         err = (dev->flags & IFF_UP) ? 0 : -ENETDOWN;
1152 out:
1153         rcu_read_unlock();
1154         return err;
1155 }
1156 
1157 static int fib_check_nh_nongw(struct net *net, struct fib_nh *nh,
1158                               struct netlink_ext_ack *extack)
1159 {
1160         struct in_device *in_dev;
1161         int err;
1162 
1163         if (nh->fib_nh_flags & (RTNH_F_PERVASIVE | RTNH_F_ONLINK)) {
1164                 NL_SET_ERR_MSG(extack,
1165                                "Invalid flags for nexthop - PERVASIVE and ONLINK can not be set");
1166                 return -EINVAL;
1167         }
1168 
1169         rcu_read_lock();
1170 
1171         err = -ENODEV;
1172         in_dev = inetdev_by_index(net, nh->fib_nh_oif);
1173         if (!in_dev)
1174                 goto out;
1175         err = -ENETDOWN;
1176         if (!(in_dev->dev->flags & IFF_UP)) {
1177                 NL_SET_ERR_MSG(extack, "Device for nexthop is not up");
1178                 goto out;
1179         }
1180 
1181         nh->fib_nh_dev = in_dev->dev;
1182         dev_hold(nh->fib_nh_dev);
1183         nh->fib_nh_scope = RT_SCOPE_HOST;
1184         if (!netif_carrier_ok(nh->fib_nh_dev))
1185                 nh->fib_nh_flags |= RTNH_F_LINKDOWN;
1186         err = 0;
1187 out:
1188         rcu_read_unlock();
1189         return err;
1190 }
1191 
1192 int fib_check_nh(struct net *net, struct fib_nh *nh, u32 table, u8 scope,
1193                  struct netlink_ext_ack *extack)
1194 {
1195         int err;
1196 
1197         if (nh->fib_nh_gw_family == AF_INET)
1198                 err = fib_check_nh_v4_gw(net, nh, table, scope, extack);
1199         else if (nh->fib_nh_gw_family == AF_INET6)
1200                 err = fib_check_nh_v6_gw(net, nh, table, extack);
1201         else
1202                 err = fib_check_nh_nongw(net, nh, extack);
1203 
1204         return err;
1205 }
1206 
1207 static inline unsigned int fib_laddr_hashfn(__be32 val)
1208 {
1209         unsigned int mask = (fib_info_hash_size - 1);
1210 
1211         return ((__force u32)val ^
1212                 ((__force u32)val >> 7) ^
1213                 ((__force u32)val >> 14)) & mask;
1214 }
1215 
1216 static struct hlist_head *fib_info_hash_alloc(int bytes)
1217 {
1218         if (bytes <= PAGE_SIZE)
1219                 return kzalloc(bytes, GFP_KERNEL);
1220         else
1221                 return (struct hlist_head *)
1222                         __get_free_pages(GFP_KERNEL | __GFP_ZERO,
1223                                          get_order(bytes));
1224 }
1225 
1226 static void fib_info_hash_free(struct hlist_head *hash, int bytes)
1227 {
1228         if (!hash)
1229                 return;
1230 
1231         if (bytes <= PAGE_SIZE)
1232                 kfree(hash);
1233         else
1234                 free_pages((unsigned long) hash, get_order(bytes));
1235 }
1236 
1237 static void fib_info_hash_move(struct hlist_head *new_info_hash,
1238                                struct hlist_head *new_laddrhash,
1239                                unsigned int new_size)
1240 {
1241         struct hlist_head *old_info_hash, *old_laddrhash;
1242         unsigned int old_size = fib_info_hash_size;
1243         unsigned int i, bytes;
1244 
1245         spin_lock_bh(&fib_info_lock);
1246         old_info_hash = fib_info_hash;
1247         old_laddrhash = fib_info_laddrhash;
1248         fib_info_hash_size = new_size;
1249 
1250         for (i = 0; i < old_size; i++) {
1251                 struct hlist_head *head = &fib_info_hash[i];
1252                 struct hlist_node *n;
1253                 struct fib_info *fi;
1254 
1255                 hlist_for_each_entry_safe(fi, n, head, fib_hash) {
1256                         struct hlist_head *dest;
1257                         unsigned int new_hash;
1258 
1259                         new_hash = fib_info_hashfn(fi);
1260                         dest = &new_info_hash[new_hash];
1261                         hlist_add_head(&fi->fib_hash, dest);
1262                 }
1263         }
1264         fib_info_hash = new_info_hash;
1265 
1266         for (i = 0; i < old_size; i++) {
1267                 struct hlist_head *lhead = &fib_info_laddrhash[i];
1268                 struct hlist_node *n;
1269                 struct fib_info *fi;
1270 
1271                 hlist_for_each_entry_safe(fi, n, lhead, fib_lhash) {
1272                         struct hlist_head *ldest;
1273                         unsigned int new_hash;
1274 
1275                         new_hash = fib_laddr_hashfn(fi->fib_prefsrc);
1276                         ldest = &new_laddrhash[new_hash];
1277                         hlist_add_head(&fi->fib_lhash, ldest);
1278                 }
1279         }
1280         fib_info_laddrhash = new_laddrhash;
1281 
1282         spin_unlock_bh(&fib_info_lock);
1283 
1284         bytes = old_size * sizeof(struct hlist_head *);
1285         fib_info_hash_free(old_info_hash, bytes);
1286         fib_info_hash_free(old_laddrhash, bytes);
1287 }
1288 
1289 __be32 fib_info_update_nhc_saddr(struct net *net, struct fib_nh_common *nhc,
1290                                  unsigned char scope)
1291 {
1292         struct fib_nh *nh;
1293 
1294         if (nhc->nhc_family != AF_INET)
1295                 return inet_select_addr(nhc->nhc_dev, 0, scope);
1296 
1297         nh = container_of(nhc, struct fib_nh, nh_common);
1298         nh->nh_saddr = inet_select_addr(nh->fib_nh_dev, nh->fib_nh_gw4, scope);
1299         nh->nh_saddr_genid = atomic_read(&net->ipv4.dev_addr_genid);
1300 
1301         return nh->nh_saddr;
1302 }
1303 
1304 __be32 fib_result_prefsrc(struct net *net, struct fib_result *res)
1305 {
1306         struct fib_nh_common *nhc = res->nhc;
1307 
1308         if (res->fi->fib_prefsrc)
1309                 return res->fi->fib_prefsrc;
1310 
1311         if (nhc->nhc_family == AF_INET) {
1312                 struct fib_nh *nh;
1313 
1314                 nh = container_of(nhc, struct fib_nh, nh_common);
1315                 if (nh->nh_saddr_genid == atomic_read(&net->ipv4.dev_addr_genid))
1316                         return nh->nh_saddr;
1317         }
1318 
1319         return fib_info_update_nhc_saddr(net, nhc, res->fi->fib_scope);
1320 }
1321 
1322 static bool fib_valid_prefsrc(struct fib_config *cfg, __be32 fib_prefsrc)
1323 {
1324         if (cfg->fc_type != RTN_LOCAL || !cfg->fc_dst ||
1325             fib_prefsrc != cfg->fc_dst) {
1326                 u32 tb_id = cfg->fc_table;
1327                 int rc;
1328 
1329                 if (tb_id == RT_TABLE_MAIN)
1330                         tb_id = RT_TABLE_LOCAL;
1331 
1332                 rc = inet_addr_type_table(cfg->fc_nlinfo.nl_net,
1333                                           fib_prefsrc, tb_id);
1334 
1335                 if (rc != RTN_LOCAL && tb_id != RT_TABLE_LOCAL) {
1336                         rc = inet_addr_type_table(cfg->fc_nlinfo.nl_net,
1337                                                   fib_prefsrc, RT_TABLE_LOCAL);
1338                 }
1339 
1340                 if (rc != RTN_LOCAL)
1341                         return false;
1342         }
1343         return true;
1344 }
1345 
1346 struct fib_info *fib_create_info(struct fib_config *cfg,
1347                                  struct netlink_ext_ack *extack)
1348 {
1349         int err;
1350         struct fib_info *fi = NULL;
1351         struct nexthop *nh = NULL;
1352         struct fib_info *ofi;
1353         int nhs = 1;
1354         struct net *net = cfg->fc_nlinfo.nl_net;
1355 
1356         if (cfg->fc_type > RTN_MAX)
1357                 goto err_inval;
1358 
1359         /* Fast check to catch the most weird cases */
1360         if (fib_props[cfg->fc_type].scope > cfg->fc_scope) {
1361                 NL_SET_ERR_MSG(extack, "Invalid scope");
1362                 goto err_inval;
1363         }
1364 
1365         if (cfg->fc_flags & (RTNH_F_DEAD | RTNH_F_LINKDOWN)) {
1366                 NL_SET_ERR_MSG(extack,
1367                                "Invalid rtm_flags - can not contain DEAD or LINKDOWN");
1368                 goto err_inval;
1369         }
1370 
1371         if (cfg->fc_nh_id) {
1372                 if (!cfg->fc_mx) {
1373                         fi = fib_find_info_nh(net, cfg);
1374                         if (fi) {
1375                                 fi->fib_treeref++;
1376                                 return fi;
1377                         }
1378                 }
1379 
1380                 nh = nexthop_find_by_id(net, cfg->fc_nh_id);
1381                 if (!nh) {
1382                         NL_SET_ERR_MSG(extack, "Nexthop id does not exist");
1383                         goto err_inval;
1384                 }
1385                 nhs = 0;
1386         }
1387 
1388 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1389         if (cfg->fc_mp) {
1390                 nhs = fib_count_nexthops(cfg->fc_mp, cfg->fc_mp_len, extack);
1391                 if (nhs == 0)
1392                         goto err_inval;
1393         }
1394 #endif
1395 
1396         err = -ENOBUFS;
1397         if (fib_info_cnt >= fib_info_hash_size) {
1398                 unsigned int new_size = fib_info_hash_size << 1;
1399                 struct hlist_head *new_info_hash;
1400                 struct hlist_head *new_laddrhash;
1401                 unsigned int bytes;
1402 
1403                 if (!new_size)
1404                         new_size = 16;
1405                 bytes = new_size * sizeof(struct hlist_head *);
1406                 new_info_hash = fib_info_hash_alloc(bytes);
1407                 new_laddrhash = fib_info_hash_alloc(bytes);
1408                 if (!new_info_hash || !new_laddrhash) {
1409                         fib_info_hash_free(new_info_hash, bytes);
1410                         fib_info_hash_free(new_laddrhash, bytes);
1411                 } else
1412                         fib_info_hash_move(new_info_hash, new_laddrhash, new_size);
1413 
1414                 if (!fib_info_hash_size)
1415                         goto failure;
1416         }
1417 
1418         fi = kzalloc(struct_size(fi, fib_nh, nhs), GFP_KERNEL);
1419         if (!fi)
1420                 goto failure;
1421         fi->fib_metrics = ip_fib_metrics_init(fi->fib_net, cfg->fc_mx,
1422                                               cfg->fc_mx_len, extack);
1423         if (IS_ERR(fi->fib_metrics)) {
1424                 err = PTR_ERR(fi->fib_metrics);
1425                 kfree(fi);
1426                 return ERR_PTR(err);
1427         }
1428 
1429         fib_info_cnt++;
1430         fi->fib_net = net;
1431         fi->fib_protocol = cfg->fc_protocol;
1432         fi->fib_scope = cfg->fc_scope;
1433         fi->fib_flags = cfg->fc_flags;
1434         fi->fib_priority = cfg->fc_priority;
1435         fi->fib_prefsrc = cfg->fc_prefsrc;
1436         fi->fib_type = cfg->fc_type;
1437         fi->fib_tb_id = cfg->fc_table;
1438 
1439         fi->fib_nhs = nhs;
1440         if (nh) {
1441                 if (!nexthop_get(nh)) {
1442                         NL_SET_ERR_MSG(extack, "Nexthop has been deleted");
1443                         err = -EINVAL;
1444                 } else {
1445                         err = 0;
1446                         fi->nh = nh;
1447                 }
1448         } else {
1449                 change_nexthops(fi) {
1450                         nexthop_nh->nh_parent = fi;
1451                 } endfor_nexthops(fi)
1452 
1453                 if (cfg->fc_mp)
1454                         err = fib_get_nhs(fi, cfg->fc_mp, cfg->fc_mp_len, cfg,
1455                                           extack);
1456                 else
1457                         err = fib_nh_init(net, fi->fib_nh, cfg, 1, extack);
1458         }
1459 
1460         if (err != 0)
1461                 goto failure;
1462 
1463         if (fib_props[cfg->fc_type].error) {
1464                 if (cfg->fc_gw_family || cfg->fc_oif || cfg->fc_mp) {
1465                         NL_SET_ERR_MSG(extack,
1466                                        "Gateway, device and multipath can not be specified for this route type");
1467                         goto err_inval;
1468                 }
1469                 goto link_it;
1470         } else {
1471                 switch (cfg->fc_type) {
1472                 case RTN_UNICAST:
1473                 case RTN_LOCAL:
1474                 case RTN_BROADCAST:
1475                 case RTN_ANYCAST:
1476                 case RTN_MULTICAST:
1477                         break;
1478                 default:
1479                         NL_SET_ERR_MSG(extack, "Invalid route type");
1480                         goto err_inval;
1481                 }
1482         }
1483 
1484         if (cfg->fc_scope > RT_SCOPE_HOST) {
1485                 NL_SET_ERR_MSG(extack, "Invalid scope");
1486                 goto err_inval;
1487         }
1488 
1489         if (fi->nh) {
1490                 err = fib_check_nexthop(fi->nh, cfg->fc_scope, extack);
1491                 if (err)
1492                         goto failure;
1493         } else if (cfg->fc_scope == RT_SCOPE_HOST) {
1494                 struct fib_nh *nh = fi->fib_nh;
1495 
1496                 /* Local address is added. */
1497                 if (nhs != 1) {
1498                         NL_SET_ERR_MSG(extack,
1499                                        "Route with host scope can not have multiple nexthops");
1500                         goto err_inval;
1501                 }
1502                 if (nh->fib_nh_gw_family) {
1503                         NL_SET_ERR_MSG(extack,
1504                                        "Route with host scope can not have a gateway");
1505                         goto err_inval;
1506                 }
1507                 nh->fib_nh_scope = RT_SCOPE_NOWHERE;
1508                 nh->fib_nh_dev = dev_get_by_index(net, nh->fib_nh_oif);
1509                 err = -ENODEV;
1510                 if (!nh->fib_nh_dev)
1511                         goto failure;
1512         } else {
1513                 int linkdown = 0;
1514 
1515                 change_nexthops(fi) {
1516                         err = fib_check_nh(cfg->fc_nlinfo.nl_net, nexthop_nh,
1517                                            cfg->fc_table, cfg->fc_scope,
1518                                            extack);
1519                         if (err != 0)
1520                                 goto failure;
1521                         if (nexthop_nh->fib_nh_flags & RTNH_F_LINKDOWN)
1522                                 linkdown++;
1523                 } endfor_nexthops(fi)
1524                 if (linkdown == fi->fib_nhs)
1525                         fi->fib_flags |= RTNH_F_LINKDOWN;
1526         }
1527 
1528         if (fi->fib_prefsrc && !fib_valid_prefsrc(cfg, fi->fib_prefsrc)) {
1529                 NL_SET_ERR_MSG(extack, "Invalid prefsrc address");
1530                 goto err_inval;
1531         }
1532 
1533         if (!fi->nh) {
1534                 change_nexthops(fi) {
1535                         fib_info_update_nhc_saddr(net, &nexthop_nh->nh_common,
1536                                                   fi->fib_scope);
1537                         if (nexthop_nh->fib_nh_gw_family == AF_INET6)
1538                                 fi->fib_nh_is_v6 = true;
1539                 } endfor_nexthops(fi)
1540 
1541                 fib_rebalance(fi);
1542         }
1543 
1544 link_it:
1545         ofi = fib_find_info(fi);
1546         if (ofi) {
1547                 fi->fib_dead = 1;
1548                 free_fib_info(fi);
1549                 ofi->fib_treeref++;
1550                 return ofi;
1551         }
1552 
1553         fi->fib_treeref++;
1554         refcount_set(&fi->fib_clntref, 1);
1555         spin_lock_bh(&fib_info_lock);
1556         hlist_add_head(&fi->fib_hash,
1557                        &fib_info_hash[fib_info_hashfn(fi)]);
1558         if (fi->fib_prefsrc) {
1559                 struct hlist_head *head;
1560 
1561                 head = &fib_info_laddrhash[fib_laddr_hashfn(fi->fib_prefsrc)];
1562                 hlist_add_head(&fi->fib_lhash, head);
1563         }
1564         if (fi->nh) {
1565                 list_add(&fi->nh_list, &nh->fi_list);
1566         } else {
1567                 change_nexthops(fi) {
1568                         struct hlist_head *head;
1569                         unsigned int hash;
1570 
1571                         if (!nexthop_nh->fib_nh_dev)
1572                                 continue;
1573                         hash = fib_devindex_hashfn(nexthop_nh->fib_nh_dev->ifindex);
1574                         head = &fib_info_devhash[hash];
1575                         hlist_add_head(&nexthop_nh->nh_hash, head);
1576                 } endfor_nexthops(fi)
1577         }
1578         spin_unlock_bh(&fib_info_lock);
1579         return fi;
1580 
1581 err_inval:
1582         err = -EINVAL;
1583 
1584 failure:
1585         if (fi) {
1586                 fi->fib_dead = 1;
1587                 free_fib_info(fi);
1588         }
1589 
1590         return ERR_PTR(err);
1591 }
1592 
1593 int fib_nexthop_info(struct sk_buff *skb, const struct fib_nh_common *nhc,
1594                      u8 rt_family, unsigned char *flags, bool skip_oif)
1595 {
1596         if (nhc->nhc_flags & RTNH_F_DEAD)
1597                 *flags |= RTNH_F_DEAD;
1598 
1599         if (nhc->nhc_flags & RTNH_F_LINKDOWN) {
1600                 *flags |= RTNH_F_LINKDOWN;
1601 
1602                 rcu_read_lock();
1603                 switch (nhc->nhc_family) {
1604                 case AF_INET:
1605                         if (ip_ignore_linkdown(nhc->nhc_dev))
1606                                 *flags |= RTNH_F_DEAD;
1607                         break;
1608                 case AF_INET6:
1609                         if (ip6_ignore_linkdown(nhc->nhc_dev))
1610                                 *flags |= RTNH_F_DEAD;
1611                         break;
1612                 }
1613                 rcu_read_unlock();
1614         }
1615 
1616         switch (nhc->nhc_gw_family) {
1617         case AF_INET:
1618                 if (nla_put_in_addr(skb, RTA_GATEWAY, nhc->nhc_gw.ipv4))
1619                         goto nla_put_failure;
1620                 break;
1621         case AF_INET6:
1622                 /* if gateway family does not match nexthop family
1623                  * gateway is encoded as RTA_VIA
1624                  */
1625                 if (rt_family != nhc->nhc_gw_family) {
1626                         int alen = sizeof(struct in6_addr);
1627                         struct nlattr *nla;
1628                         struct rtvia *via;
1629 
1630                         nla = nla_reserve(skb, RTA_VIA, alen + 2);
1631                         if (!nla)
1632                                 goto nla_put_failure;
1633 
1634                         via = nla_data(nla);
1635                         via->rtvia_family = AF_INET6;
1636                         memcpy(via->rtvia_addr, &nhc->nhc_gw.ipv6, alen);
1637                 } else if (nla_put_in6_addr(skb, RTA_GATEWAY,
1638                                             &nhc->nhc_gw.ipv6) < 0) {
1639                         goto nla_put_failure;
1640                 }
1641                 break;
1642         }
1643 
1644         *flags |= (nhc->nhc_flags & RTNH_F_ONLINK);
1645         if (nhc->nhc_flags & RTNH_F_OFFLOAD)
1646                 *flags |= RTNH_F_OFFLOAD;
1647 
1648         if (!skip_oif && nhc->nhc_dev &&
1649             nla_put_u32(skb, RTA_OIF, nhc->nhc_dev->ifindex))
1650                 goto nla_put_failure;
1651 
1652         if (nhc->nhc_lwtstate &&
1653             lwtunnel_fill_encap(skb, nhc->nhc_lwtstate,
1654                                 RTA_ENCAP, RTA_ENCAP_TYPE) < 0)
1655                 goto nla_put_failure;
1656 
1657         return 0;
1658 
1659 nla_put_failure:
1660         return -EMSGSIZE;
1661 }
1662 EXPORT_SYMBOL_GPL(fib_nexthop_info);
1663 
1664 #if IS_ENABLED(CONFIG_IP_ROUTE_MULTIPATH) || IS_ENABLED(CONFIG_IPV6)
1665 int fib_add_nexthop(struct sk_buff *skb, const struct fib_nh_common *nhc,
1666                     int nh_weight, u8 rt_family)
1667 {
1668         const struct net_device *dev = nhc->nhc_dev;
1669         struct rtnexthop *rtnh;
1670         unsigned char flags = 0;
1671 
1672         rtnh = nla_reserve_nohdr(skb, sizeof(*rtnh));
1673         if (!rtnh)
1674                 goto nla_put_failure;
1675 
1676         rtnh->rtnh_hops = nh_weight - 1;
1677         rtnh->rtnh_ifindex = dev ? dev->ifindex : 0;
1678 
1679         if (fib_nexthop_info(skb, nhc, rt_family, &flags, true) < 0)
1680                 goto nla_put_failure;
1681 
1682         rtnh->rtnh_flags = flags;
1683 
1684         /* length of rtnetlink header + attributes */
1685         rtnh->rtnh_len = nlmsg_get_pos(skb) - (void *)rtnh;
1686 
1687         return 0;
1688 
1689 nla_put_failure:
1690         return -EMSGSIZE;
1691 }
1692 EXPORT_SYMBOL_GPL(fib_add_nexthop);
1693 #endif
1694 
1695 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1696 static int fib_add_multipath(struct sk_buff *skb, struct fib_info *fi)
1697 {
1698         struct nlattr *mp;
1699 
1700         mp = nla_nest_start_noflag(skb, RTA_MULTIPATH);
1701         if (!mp)
1702                 goto nla_put_failure;
1703 
1704         if (unlikely(fi->nh)) {
1705                 if (nexthop_mpath_fill_node(skb, fi->nh, AF_INET) < 0)
1706                         goto nla_put_failure;
1707                 goto mp_end;
1708         }
1709 
1710         for_nexthops(fi) {
1711                 if (fib_add_nexthop(skb, &nh->nh_common, nh->fib_nh_weight,
1712                                     AF_INET) < 0)
1713                         goto nla_put_failure;
1714 #ifdef CONFIG_IP_ROUTE_CLASSID
1715                 if (nh->nh_tclassid &&
1716                     nla_put_u32(skb, RTA_FLOW, nh->nh_tclassid))
1717                         goto nla_put_failure;
1718 #endif
1719         } endfor_nexthops(fi);
1720 
1721 mp_end:
1722         nla_nest_end(skb, mp);
1723 
1724         return 0;
1725 
1726 nla_put_failure:
1727         return -EMSGSIZE;
1728 }
1729 #else
1730 static int fib_add_multipath(struct sk_buff *skb, struct fib_info *fi)
1731 {
1732         return 0;
1733 }
1734 #endif
1735 
1736 int fib_dump_info(struct sk_buff *skb, u32 portid, u32 seq, int event,
1737                   struct fib_rt_info *fri, unsigned int flags)
1738 {
1739         unsigned int nhs = fib_info_num_path(fri->fi);
1740         struct fib_info *fi = fri->fi;
1741         u32 tb_id = fri->tb_id;
1742         struct nlmsghdr *nlh;
1743         struct rtmsg *rtm;
1744 
1745         nlh = nlmsg_put(skb, portid, seq, event, sizeof(*rtm), flags);
1746         if (!nlh)
1747                 return -EMSGSIZE;
1748 
1749         rtm = nlmsg_data(nlh);
1750         rtm->rtm_family = AF_INET;
1751         rtm->rtm_dst_len = fri->dst_len;
1752         rtm->rtm_src_len = 0;
1753         rtm->rtm_tos = fri->tos;
1754         if (tb_id < 256)
1755                 rtm->rtm_table = tb_id;
1756         else
1757                 rtm->rtm_table = RT_TABLE_COMPAT;
1758         if (nla_put_u32(skb, RTA_TABLE, tb_id))
1759                 goto nla_put_failure;
1760         rtm->rtm_type = fri->type;
1761         rtm->rtm_flags = fi->fib_flags;
1762         rtm->rtm_scope = fi->fib_scope;
1763         rtm->rtm_protocol = fi->fib_protocol;
1764 
1765         if (rtm->rtm_dst_len &&
1766             nla_put_in_addr(skb, RTA_DST, fri->dst))
1767                 goto nla_put_failure;
1768         if (fi->fib_priority &&
1769             nla_put_u32(skb, RTA_PRIORITY, fi->fib_priority))
1770                 goto nla_put_failure;
1771         if (rtnetlink_put_metrics(skb, fi->fib_metrics->metrics) < 0)
1772                 goto nla_put_failure;
1773 
1774         if (fi->fib_prefsrc &&
1775             nla_put_in_addr(skb, RTA_PREFSRC, fi->fib_prefsrc))
1776                 goto nla_put_failure;
1777 
1778         if (fi->nh) {
1779                 if (nla_put_u32(skb, RTA_NH_ID, fi->nh->id))
1780                         goto nla_put_failure;
1781                 if (nexthop_is_blackhole(fi->nh))
1782                         rtm->rtm_type = RTN_BLACKHOLE;
1783                 if (!fi->fib_net->ipv4.sysctl_nexthop_compat_mode)
1784                         goto offload;
1785         }
1786 
1787         if (nhs == 1) {
1788                 const struct fib_nh_common *nhc = fib_info_nhc(fi, 0);
1789                 unsigned char flags = 0;
1790 
1791                 if (fib_nexthop_info(skb, nhc, AF_INET, &flags, false) < 0)
1792                         goto nla_put_failure;
1793 
1794                 rtm->rtm_flags = flags;
1795 #ifdef CONFIG_IP_ROUTE_CLASSID
1796                 if (nhc->nhc_family == AF_INET) {
1797                         struct fib_nh *nh;
1798 
1799                         nh = container_of(nhc, struct fib_nh, nh_common);
1800                         if (nh->nh_tclassid &&
1801                             nla_put_u32(skb, RTA_FLOW, nh->nh_tclassid))
1802                                 goto nla_put_failure;
1803                 }
1804 #endif
1805         } else {
1806                 if (fib_add_multipath(skb, fi) < 0)
1807                         goto nla_put_failure;
1808         }
1809 
1810 offload:
1811         if (fri->offload)
1812                 rtm->rtm_flags |= RTM_F_OFFLOAD;
1813         if (fri->trap)
1814                 rtm->rtm_flags |= RTM_F_TRAP;
1815 
1816         nlmsg_end(skb, nlh);
1817         return 0;
1818 
1819 nla_put_failure:
1820         nlmsg_cancel(skb, nlh);
1821         return -EMSGSIZE;
1822 }
1823 
1824 /*
1825  * Update FIB if:
1826  * - local address disappeared -> we must delete all the entries
1827  *   referring to it.
1828  * - device went down -> we must shutdown all nexthops going via it.
1829  */
1830 int fib_sync_down_addr(struct net_device *dev, __be32 local)
1831 {
1832         int ret = 0;
1833         unsigned int hash = fib_laddr_hashfn(local);
1834         struct hlist_head *head = &fib_info_laddrhash[hash];
1835         int tb_id = l3mdev_fib_table(dev) ? : RT_TABLE_MAIN;
1836         struct net *net = dev_net(dev);
1837         struct fib_info *fi;
1838 
1839         if (!fib_info_laddrhash || local == 0)
1840                 return 0;
1841 
1842         hlist_for_each_entry(fi, head, fib_lhash) {
1843                 if (!net_eq(fi->fib_net, net) ||
1844                     fi->fib_tb_id != tb_id)
1845                         continue;
1846                 if (fi->fib_prefsrc == local) {
1847                         fi->fib_flags |= RTNH_F_DEAD;
1848                         ret++;
1849                 }
1850         }
1851         return ret;
1852 }
1853 
1854 static int call_fib_nh_notifiers(struct fib_nh *nh,
1855                                  enum fib_event_type event_type)
1856 {
1857         bool ignore_link_down = ip_ignore_linkdown(nh->fib_nh_dev);
1858         struct fib_nh_notifier_info info = {
1859                 .fib_nh = nh,
1860         };
1861 
1862         switch (event_type) {
1863         case FIB_EVENT_NH_ADD:
1864                 if (nh->fib_nh_flags & RTNH_F_DEAD)
1865                         break;
1866                 if (ignore_link_down && nh->fib_nh_flags & RTNH_F_LINKDOWN)
1867                         break;
1868                 return call_fib4_notifiers(dev_net(nh->fib_nh_dev), event_type,
1869                                            &info.info);
1870         case FIB_EVENT_NH_DEL:
1871                 if ((ignore_link_down && nh->fib_nh_flags & RTNH_F_LINKDOWN) ||
1872                     (nh->fib_nh_flags & RTNH_F_DEAD))
1873                         return call_fib4_notifiers(dev_net(nh->fib_nh_dev),
1874                                                    event_type, &info.info);
1875         default:
1876                 break;
1877         }
1878 
1879         return NOTIFY_DONE;
1880 }
1881 
1882 /* Update the PMTU of exceptions when:
1883  * - the new MTU of the first hop becomes smaller than the PMTU
1884  * - the old MTU was the same as the PMTU, and it limited discovery of
1885  *   larger MTUs on the path. With that limit raised, we can now
1886  *   discover larger MTUs
1887  * A special case is locked exceptions, for which the PMTU is smaller
1888  * than the minimal accepted PMTU:
1889  * - if the new MTU is greater than the PMTU, don't make any change
1890  * - otherwise, unlock and set PMTU
1891  */
1892 void fib_nhc_update_mtu(struct fib_nh_common *nhc, u32 new, u32 orig)
1893 {
1894         struct fnhe_hash_bucket *bucket;
1895         int i;
1896 
1897         bucket = rcu_dereference_protected(nhc->nhc_exceptions, 1);
1898         if (!bucket)
1899                 return;
1900 
1901         for (i = 0; i < FNHE_HASH_SIZE; i++) {
1902                 struct fib_nh_exception *fnhe;
1903 
1904                 for (fnhe = rcu_dereference_protected(bucket[i].chain, 1);
1905                      fnhe;
1906                      fnhe = rcu_dereference_protected(fnhe->fnhe_next, 1)) {
1907                         if (fnhe->fnhe_mtu_locked) {
1908                                 if (new <= fnhe->fnhe_pmtu) {
1909                                         fnhe->fnhe_pmtu = new;
1910                                         fnhe->fnhe_mtu_locked = false;
1911                                 }
1912                         } else if (new < fnhe->fnhe_pmtu ||
1913                                    orig == fnhe->fnhe_pmtu) {
1914                                 fnhe->fnhe_pmtu = new;
1915                         }
1916                 }
1917         }
1918 }
1919 
1920 void fib_sync_mtu(struct net_device *dev, u32 orig_mtu)
1921 {
1922         unsigned int hash = fib_devindex_hashfn(dev->ifindex);
1923         struct hlist_head *head = &fib_info_devhash[hash];
1924         struct fib_nh *nh;
1925 
1926         hlist_for_each_entry(nh, head, nh_hash) {
1927                 if (nh->fib_nh_dev == dev)
1928                         fib_nhc_update_mtu(&nh->nh_common, dev->mtu, orig_mtu);
1929         }
1930 }
1931 
1932 /* Event              force Flags           Description
1933  * NETDEV_CHANGE      0     LINKDOWN        Carrier OFF, not for scope host
1934  * NETDEV_DOWN        0     LINKDOWN|DEAD   Link down, not for scope host
1935  * NETDEV_DOWN        1     LINKDOWN|DEAD   Last address removed
1936  * NETDEV_UNREGISTER  1     LINKDOWN|DEAD   Device removed
1937  *
1938  * only used when fib_nh is built into fib_info
1939  */
1940 int fib_sync_down_dev(struct net_device *dev, unsigned long event, bool force)
1941 {
1942         int ret = 0;
1943         int scope = RT_SCOPE_NOWHERE;
1944         struct fib_info *prev_fi = NULL;
1945         unsigned int hash = fib_devindex_hashfn(dev->ifindex);
1946         struct hlist_head *head = &fib_info_devhash[hash];
1947         struct fib_nh *nh;
1948 
1949         if (force)
1950                 scope = -1;
1951 
1952         hlist_for_each_entry(nh, head, nh_hash) {
1953                 struct fib_info *fi = nh->nh_parent;
1954                 int dead;
1955 
1956                 BUG_ON(!fi->fib_nhs);
1957                 if (nh->fib_nh_dev != dev || fi == prev_fi)
1958                         continue;
1959                 prev_fi = fi;
1960                 dead = 0;
1961                 change_nexthops(fi) {
1962                         if (nexthop_nh->fib_nh_flags & RTNH_F_DEAD)
1963                                 dead++;
1964                         else if (nexthop_nh->fib_nh_dev == dev &&
1965                                  nexthop_nh->fib_nh_scope != scope) {
1966                                 switch (event) {
1967                                 case NETDEV_DOWN:
1968                                 case NETDEV_UNREGISTER:
1969                                         nexthop_nh->fib_nh_flags |= RTNH_F_DEAD;
1970                                         fallthrough;
1971                                 case NETDEV_CHANGE:
1972                                         nexthop_nh->fib_nh_flags |= RTNH_F_LINKDOWN;
1973                                         break;
1974                                 }
1975                                 call_fib_nh_notifiers(nexthop_nh,
1976                                                       FIB_EVENT_NH_DEL);
1977                                 dead++;
1978                         }
1979 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1980                         if (event == NETDEV_UNREGISTER &&
1981                             nexthop_nh->fib_nh_dev == dev) {
1982                                 dead = fi->fib_nhs;
1983                                 break;
1984                         }
1985 #endif
1986                 } endfor_nexthops(fi)
1987                 if (dead == fi->fib_nhs) {
1988                         switch (event) {
1989                         case NETDEV_DOWN:
1990                         case NETDEV_UNREGISTER:
1991                                 fi->fib_flags |= RTNH_F_DEAD;
1992                                 fallthrough;
1993                         case NETDEV_CHANGE:
1994                                 fi->fib_flags |= RTNH_F_LINKDOWN;
1995                                 break;
1996                         }
1997                         ret++;
1998                 }
1999 
2000                 fib_rebalance(fi);
2001         }
2002 
2003         return ret;
2004 }
2005 
2006 /* Must be invoked inside of an RCU protected region.  */
2007 static void fib_select_default(const struct flowi4 *flp, struct fib_result *res)
2008 {
2009         struct fib_info *fi = NULL, *last_resort = NULL;
2010         struct hlist_head *fa_head = res->fa_head;
2011         struct fib_table *tb = res->table;
2012         u8 slen = 32 - res->prefixlen;
2013         int order = -1, last_idx = -1;
2014         struct fib_alias *fa, *fa1 = NULL;
2015         u32 last_prio = res->fi->fib_priority;
2016         u8 last_tos = 0;
2017 
2018         hlist_for_each_entry_rcu(fa, fa_head, fa_list) {
2019                 struct fib_info *next_fi = fa->fa_info;
2020                 struct fib_nh_common *nhc;
2021 
2022                 if (fa->fa_slen != slen)
2023                         continue;
2024                 if (fa->fa_tos && fa->fa_tos != flp->flowi4_tos)
2025                         continue;
2026                 if (fa->tb_id != tb->tb_id)
2027                         continue;
2028                 if (next_fi->fib_priority > last_prio &&
2029                     fa->fa_tos == last_tos) {
2030                         if (last_tos)
2031                                 continue;
2032                         break;
2033                 }
2034                 if (next_fi->fib_flags & RTNH_F_DEAD)
2035                         continue;
2036                 last_tos = fa->fa_tos;
2037                 last_prio = next_fi->fib_priority;
2038 
2039                 if (next_fi->fib_scope != res->scope ||
2040                     fa->fa_type != RTN_UNICAST)
2041                         continue;
2042 
2043                 nhc = fib_info_nhc(next_fi, 0);
2044                 if (!nhc->nhc_gw_family || nhc->nhc_scope != RT_SCOPE_LINK)
2045                         continue;
2046 
2047                 fib_alias_accessed(fa);
2048 
2049                 if (!fi) {
2050                         if (next_fi != res->fi)
2051                                 break;
2052                         fa1 = fa;
2053                 } else if (!fib_detect_death(fi, order, &last_resort,
2054                                              &last_idx, fa1->fa_default)) {
2055                         fib_result_assign(res, fi);
2056                         fa1->fa_default = order;
2057                         goto out;
2058                 }
2059                 fi = next_fi;
2060                 order++;
2061         }
2062 
2063         if (order <= 0 || !fi) {
2064                 if (fa1)
2065                         fa1->fa_default = -1;
2066                 goto out;
2067         }
2068 
2069         if (!fib_detect_death(fi, order, &last_resort, &last_idx,
2070                               fa1->fa_default)) {
2071                 fib_result_assign(res, fi);
2072                 fa1->fa_default = order;
2073                 goto out;
2074         }
2075 
2076         if (last_idx >= 0)
2077                 fib_result_assign(res, last_resort);
2078         fa1->fa_default = last_idx;
2079 out:
2080         return;
2081 }
2082 
2083 /*
2084  * Dead device goes up. We wake up dead nexthops.
2085  * It takes sense only on multipath routes.
2086  *
2087  * only used when fib_nh is built into fib_info
2088  */
2089 int fib_sync_up(struct net_device *dev, unsigned char nh_flags)
2090 {
2091         struct fib_info *prev_fi;
2092         unsigned int hash;
2093         struct hlist_head *head;
2094         struct fib_nh *nh;
2095         int ret;
2096 
2097         if (!(dev->flags & IFF_UP))
2098                 return 0;
2099 
2100         if (nh_flags & RTNH_F_DEAD) {
2101                 unsigned int flags = dev_get_flags(dev);
2102 
2103                 if (flags & (IFF_RUNNING | IFF_LOWER_UP))
2104                         nh_flags |= RTNH_F_LINKDOWN;
2105         }
2106 
2107         prev_fi = NULL;
2108         hash = fib_devindex_hashfn(dev->ifindex);
2109         head = &fib_info_devhash[hash];
2110         ret = 0;
2111 
2112         hlist_for_each_entry(nh, head, nh_hash) {
2113                 struct fib_info *fi = nh->nh_parent;
2114                 int alive;
2115 
2116                 BUG_ON(!fi->fib_nhs);
2117                 if (nh->fib_nh_dev != dev || fi == prev_fi)
2118                         continue;
2119 
2120                 prev_fi = fi;
2121                 alive = 0;
2122                 change_nexthops(fi) {
2123                         if (!(nexthop_nh->fib_nh_flags & nh_flags)) {
2124                                 alive++;
2125                                 continue;
2126                         }
2127                         if (!nexthop_nh->fib_nh_dev ||
2128                             !(nexthop_nh->fib_nh_dev->flags & IFF_UP))
2129                                 continue;
2130                         if (nexthop_nh->fib_nh_dev != dev ||
2131                             !__in_dev_get_rtnl(dev))
2132                                 continue;
2133                         alive++;
2134                         nexthop_nh->fib_nh_flags &= ~nh_flags;
2135                         call_fib_nh_notifiers(nexthop_nh, FIB_EVENT_NH_ADD);
2136                 } endfor_nexthops(fi)
2137 
2138                 if (alive > 0) {
2139                         fi->fib_flags &= ~nh_flags;
2140                         ret++;
2141                 }
2142 
2143                 fib_rebalance(fi);
2144         }
2145 
2146         return ret;
2147 }
2148 
2149 #ifdef CONFIG_IP_ROUTE_MULTIPATH
2150 static bool fib_good_nh(const struct fib_nh *nh)
2151 {
2152         int state = NUD_REACHABLE;
2153 
2154         if (nh->fib_nh_scope == RT_SCOPE_LINK) {
2155                 struct neighbour *n;
2156 
2157                 rcu_read_lock_bh();
2158 
2159                 if (likely(nh->fib_nh_gw_family == AF_INET))
2160                         n = __ipv4_neigh_lookup_noref(nh->fib_nh_dev,
2161                                                    (__force u32)nh->fib_nh_gw4);
2162                 else if (nh->fib_nh_gw_family == AF_INET6)
2163                         n = __ipv6_neigh_lookup_noref_stub(nh->fib_nh_dev,
2164                                                            &nh->fib_nh_gw6);
2165                 else
2166                         n = NULL;
2167                 if (n)
2168                         state = n->nud_state;
2169 
2170                 rcu_read_unlock_bh();
2171         }
2172 
2173         return !!(state & NUD_VALID);
2174 }
2175 
2176 void fib_select_multipath(struct fib_result *res, int hash)
2177 {
2178         struct fib_info *fi = res->fi;
2179         struct net *net = fi->fib_net;
2180         bool first = false;
2181 
2182         if (unlikely(res->fi->nh)) {
2183                 nexthop_path_fib_result(res, hash);
2184                 return;
2185         }
2186 
2187         change_nexthops(fi) {
2188                 if (net->ipv4.sysctl_fib_multipath_use_neigh) {
2189                         if (!fib_good_nh(nexthop_nh))
2190                                 continue;
2191                         if (!first) {
2192                                 res->nh_sel = nhsel;
2193                                 res->nhc = &nexthop_nh->nh_common;
2194                                 first = true;
2195                         }
2196                 }
2197 
2198                 if (hash > atomic_read(&nexthop_nh->fib_nh_upper_bound))
2199                         continue;
2200 
2201                 res->nh_sel = nhsel;
2202                 res->nhc = &nexthop_nh->nh_common;
2203                 return;
2204         } endfor_nexthops(fi);
2205 }
2206 #endif
2207 
2208 void fib_select_path(struct net *net, struct fib_result *res,
2209                      struct flowi4 *fl4, const struct sk_buff *skb)
2210 {
2211         if (fl4->flowi4_oif && !(fl4->flowi4_flags & FLOWI_FLAG_SKIP_NH_OIF))
2212                 goto check_saddr;
2213 
2214 #ifdef CONFIG_IP_ROUTE_MULTIPATH
2215         if (fib_info_num_path(res->fi) > 1) {
2216                 int h = fib_multipath_hash(net, fl4, skb, NULL);
2217 
2218                 fib_select_multipath(res, h);
2219         }
2220         else
2221 #endif
2222         if (!res->prefixlen &&
2223             res->table->tb_num_default > 1 &&
2224             res->type == RTN_UNICAST)
2225                 fib_select_default(fl4, res);
2226 
2227 check_saddr:
2228         if (!fl4->saddr)
2229                 fl4->saddr = fib_result_prefsrc(net, res);
2230 }
2231 

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