ipv4: fix NULL dereference in free_fib_info_rcu()
[karo-tx-linux.git] / net / ipv4 / fib_semantics.c
1 /*
2  * INET         An implementation of the TCP/IP protocol suite for the LINUX
3  *              operating system.  INET is implemented using the  BSD Socket
4  *              interface as the means of communication with the user level.
5  *
6  *              IPv4 Forwarding Information Base: semantics.
7  *
8  * Authors:     Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
9  *
10  *              This program is free software; you can redistribute it and/or
11  *              modify it under the terms of the GNU General Public License
12  *              as published by the Free Software Foundation; either version
13  *              2 of the License, or (at your option) any later version.
14  */
15
16 #include <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
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 #ifdef CONFIG_IP_ROUTE_MULTIPATH
61
62 #define for_nexthops(fi) {                                              \
63         int nhsel; const struct fib_nh *nh;                             \
64         for (nhsel = 0, nh = (fi)->fib_nh;                              \
65              nhsel < (fi)->fib_nhs;                                     \
66              nh++, nhsel++)
67
68 #define change_nexthops(fi) {                                           \
69         int nhsel; struct fib_nh *nexthop_nh;                           \
70         for (nhsel = 0, nexthop_nh = (struct fib_nh *)((fi)->fib_nh);   \
71              nhsel < (fi)->fib_nhs;                                     \
72              nexthop_nh++, nhsel++)
73
74 #else /* CONFIG_IP_ROUTE_MULTIPATH */
75
76 /* Hope, that gcc will optimize it to get rid of dummy loop */
77
78 #define for_nexthops(fi) {                                              \
79         int nhsel; const struct fib_nh *nh = (fi)->fib_nh;              \
80         for (nhsel = 0; nhsel < 1; nhsel++)
81
82 #define change_nexthops(fi) {                                           \
83         int nhsel;                                                      \
84         struct fib_nh *nexthop_nh = (struct fib_nh *)((fi)->fib_nh);    \
85         for (nhsel = 0; nhsel < 1; nhsel++)
86
87 #endif /* CONFIG_IP_ROUTE_MULTIPATH */
88
89 #define endfor_nexthops(fi) }
90
91
92 const struct fib_prop fib_props[RTN_MAX + 1] = {
93         [RTN_UNSPEC] = {
94                 .error  = 0,
95                 .scope  = RT_SCOPE_NOWHERE,
96         },
97         [RTN_UNICAST] = {
98                 .error  = 0,
99                 .scope  = RT_SCOPE_UNIVERSE,
100         },
101         [RTN_LOCAL] = {
102                 .error  = 0,
103                 .scope  = RT_SCOPE_HOST,
104         },
105         [RTN_BROADCAST] = {
106                 .error  = 0,
107                 .scope  = RT_SCOPE_LINK,
108         },
109         [RTN_ANYCAST] = {
110                 .error  = 0,
111                 .scope  = RT_SCOPE_LINK,
112         },
113         [RTN_MULTICAST] = {
114                 .error  = 0,
115                 .scope  = RT_SCOPE_UNIVERSE,
116         },
117         [RTN_BLACKHOLE] = {
118                 .error  = -EINVAL,
119                 .scope  = RT_SCOPE_UNIVERSE,
120         },
121         [RTN_UNREACHABLE] = {
122                 .error  = -EHOSTUNREACH,
123                 .scope  = RT_SCOPE_UNIVERSE,
124         },
125         [RTN_PROHIBIT] = {
126                 .error  = -EACCES,
127                 .scope  = RT_SCOPE_UNIVERSE,
128         },
129         [RTN_THROW] = {
130                 .error  = -EAGAIN,
131                 .scope  = RT_SCOPE_UNIVERSE,
132         },
133         [RTN_NAT] = {
134                 .error  = -EINVAL,
135                 .scope  = RT_SCOPE_NOWHERE,
136         },
137         [RTN_XRESOLVE] = {
138                 .error  = -EINVAL,
139                 .scope  = RT_SCOPE_NOWHERE,
140         },
141 };
142
143 static void rt_fibinfo_free(struct rtable __rcu **rtp)
144 {
145         struct rtable *rt = rcu_dereference_protected(*rtp, 1);
146
147         if (!rt)
148                 return;
149
150         /* Not even needed : RCU_INIT_POINTER(*rtp, NULL);
151          * because we waited an RCU grace period before calling
152          * free_fib_info_rcu()
153          */
154
155         dst_dev_put(&rt->dst);
156         dst_release_immediate(&rt->dst);
157 }
158
159 static void free_nh_exceptions(struct fib_nh *nh)
160 {
161         struct fnhe_hash_bucket *hash;
162         int i;
163
164         hash = rcu_dereference_protected(nh->nh_exceptions, 1);
165         if (!hash)
166                 return;
167         for (i = 0; i < FNHE_HASH_SIZE; i++) {
168                 struct fib_nh_exception *fnhe;
169
170                 fnhe = rcu_dereference_protected(hash[i].chain, 1);
171                 while (fnhe) {
172                         struct fib_nh_exception *next;
173                         
174                         next = rcu_dereference_protected(fnhe->fnhe_next, 1);
175
176                         rt_fibinfo_free(&fnhe->fnhe_rth_input);
177                         rt_fibinfo_free(&fnhe->fnhe_rth_output);
178
179                         kfree(fnhe);
180
181                         fnhe = next;
182                 }
183         }
184         kfree(hash);
185 }
186
187 static void rt_fibinfo_free_cpus(struct rtable __rcu * __percpu *rtp)
188 {
189         int cpu;
190
191         if (!rtp)
192                 return;
193
194         for_each_possible_cpu(cpu) {
195                 struct rtable *rt;
196
197                 rt = rcu_dereference_protected(*per_cpu_ptr(rtp, cpu), 1);
198                 if (rt) {
199                         dst_dev_put(&rt->dst);
200                         dst_release_immediate(&rt->dst);
201                 }
202         }
203         free_percpu(rtp);
204 }
205
206 /* Release a nexthop info record */
207 static void free_fib_info_rcu(struct rcu_head *head)
208 {
209         struct fib_info *fi = container_of(head, struct fib_info, rcu);
210         struct dst_metrics *m;
211
212         change_nexthops(fi) {
213                 if (nexthop_nh->nh_dev)
214                         dev_put(nexthop_nh->nh_dev);
215                 lwtstate_put(nexthop_nh->nh_lwtstate);
216                 free_nh_exceptions(nexthop_nh);
217                 rt_fibinfo_free_cpus(nexthop_nh->nh_pcpu_rth_output);
218                 rt_fibinfo_free(&nexthop_nh->nh_rth_input);
219         } endfor_nexthops(fi);
220
221         m = fi->fib_metrics;
222         if (m != &dst_default_metrics && atomic_dec_and_test(&m->refcnt))
223                 kfree(m);
224         kfree(fi);
225 }
226
227 void free_fib_info(struct fib_info *fi)
228 {
229         if (fi->fib_dead == 0) {
230                 pr_warn("Freeing alive fib_info %p\n", fi);
231                 return;
232         }
233         fib_info_cnt--;
234 #ifdef CONFIG_IP_ROUTE_CLASSID
235         change_nexthops(fi) {
236                 if (nexthop_nh->nh_tclassid)
237                         fi->fib_net->ipv4.fib_num_tclassid_users--;
238         } endfor_nexthops(fi);
239 #endif
240         call_rcu(&fi->rcu, free_fib_info_rcu);
241 }
242 EXPORT_SYMBOL_GPL(free_fib_info);
243
244 void fib_release_info(struct fib_info *fi)
245 {
246         spin_lock_bh(&fib_info_lock);
247         if (fi && --fi->fib_treeref == 0) {
248                 hlist_del(&fi->fib_hash);
249                 if (fi->fib_prefsrc)
250                         hlist_del(&fi->fib_lhash);
251                 change_nexthops(fi) {
252                         if (!nexthop_nh->nh_dev)
253                                 continue;
254                         hlist_del(&nexthop_nh->nh_hash);
255                 } endfor_nexthops(fi)
256                 fi->fib_dead = 1;
257                 fib_info_put(fi);
258         }
259         spin_unlock_bh(&fib_info_lock);
260 }
261
262 static inline int nh_comp(const struct fib_info *fi, const struct fib_info *ofi)
263 {
264         const struct fib_nh *onh = ofi->fib_nh;
265
266         for_nexthops(fi) {
267                 if (nh->nh_oif != onh->nh_oif ||
268                     nh->nh_gw  != onh->nh_gw ||
269                     nh->nh_scope != onh->nh_scope ||
270 #ifdef CONFIG_IP_ROUTE_MULTIPATH
271                     nh->nh_weight != onh->nh_weight ||
272 #endif
273 #ifdef CONFIG_IP_ROUTE_CLASSID
274                     nh->nh_tclassid != onh->nh_tclassid ||
275 #endif
276                     lwtunnel_cmp_encap(nh->nh_lwtstate, onh->nh_lwtstate) ||
277                     ((nh->nh_flags ^ onh->nh_flags) & ~RTNH_COMPARE_MASK))
278                         return -1;
279                 onh++;
280         } endfor_nexthops(fi);
281         return 0;
282 }
283
284 static inline unsigned int fib_devindex_hashfn(unsigned int val)
285 {
286         unsigned int mask = DEVINDEX_HASHSIZE - 1;
287
288         return (val ^
289                 (val >> DEVINDEX_HASHBITS) ^
290                 (val >> (DEVINDEX_HASHBITS * 2))) & mask;
291 }
292
293 static inline unsigned int fib_info_hashfn(const struct fib_info *fi)
294 {
295         unsigned int mask = (fib_info_hash_size - 1);
296         unsigned int val = fi->fib_nhs;
297
298         val ^= (fi->fib_protocol << 8) | fi->fib_scope;
299         val ^= (__force u32)fi->fib_prefsrc;
300         val ^= fi->fib_priority;
301         for_nexthops(fi) {
302                 val ^= fib_devindex_hashfn(nh->nh_oif);
303         } endfor_nexthops(fi)
304
305         return (val ^ (val >> 7) ^ (val >> 12)) & mask;
306 }
307
308 static struct fib_info *fib_find_info(const struct fib_info *nfi)
309 {
310         struct hlist_head *head;
311         struct fib_info *fi;
312         unsigned int hash;
313
314         hash = fib_info_hashfn(nfi);
315         head = &fib_info_hash[hash];
316
317         hlist_for_each_entry(fi, head, fib_hash) {
318                 if (!net_eq(fi->fib_net, nfi->fib_net))
319                         continue;
320                 if (fi->fib_nhs != nfi->fib_nhs)
321                         continue;
322                 if (nfi->fib_protocol == fi->fib_protocol &&
323                     nfi->fib_scope == fi->fib_scope &&
324                     nfi->fib_prefsrc == fi->fib_prefsrc &&
325                     nfi->fib_priority == fi->fib_priority &&
326                     nfi->fib_type == fi->fib_type &&
327                     memcmp(nfi->fib_metrics, fi->fib_metrics,
328                            sizeof(u32) * RTAX_MAX) == 0 &&
329                     !((nfi->fib_flags ^ fi->fib_flags) & ~RTNH_COMPARE_MASK) &&
330                     (nfi->fib_nhs == 0 || nh_comp(fi, nfi) == 0))
331                         return fi;
332         }
333
334         return NULL;
335 }
336
337 /* Check, that the gateway is already configured.
338  * Used only by redirect accept routine.
339  */
340 int ip_fib_check_default(__be32 gw, struct net_device *dev)
341 {
342         struct hlist_head *head;
343         struct fib_nh *nh;
344         unsigned int hash;
345
346         spin_lock(&fib_info_lock);
347
348         hash = fib_devindex_hashfn(dev->ifindex);
349         head = &fib_info_devhash[hash];
350         hlist_for_each_entry(nh, head, nh_hash) {
351                 if (nh->nh_dev == dev &&
352                     nh->nh_gw == gw &&
353                     !(nh->nh_flags & RTNH_F_DEAD)) {
354                         spin_unlock(&fib_info_lock);
355                         return 0;
356                 }
357         }
358
359         spin_unlock(&fib_info_lock);
360
361         return -1;
362 }
363
364 static inline size_t fib_nlmsg_size(struct fib_info *fi)
365 {
366         size_t payload = NLMSG_ALIGN(sizeof(struct rtmsg))
367                          + nla_total_size(4) /* RTA_TABLE */
368                          + nla_total_size(4) /* RTA_DST */
369                          + nla_total_size(4) /* RTA_PRIORITY */
370                          + nla_total_size(4) /* RTA_PREFSRC */
371                          + nla_total_size(TCP_CA_NAME_MAX); /* RTAX_CC_ALGO */
372
373         /* space for nested metrics */
374         payload += nla_total_size((RTAX_MAX * nla_total_size(4)));
375
376         if (fi->fib_nhs) {
377                 size_t nh_encapsize = 0;
378                 /* Also handles the special case fib_nhs == 1 */
379
380                 /* each nexthop is packed in an attribute */
381                 size_t nhsize = nla_total_size(sizeof(struct rtnexthop));
382
383                 /* may contain flow and gateway attribute */
384                 nhsize += 2 * nla_total_size(4);
385
386                 /* grab encap info */
387                 for_nexthops(fi) {
388                         if (nh->nh_lwtstate) {
389                                 /* RTA_ENCAP_TYPE */
390                                 nh_encapsize += lwtunnel_get_encap_size(
391                                                 nh->nh_lwtstate);
392                                 /* RTA_ENCAP */
393                                 nh_encapsize +=  nla_total_size(2);
394                         }
395                 } endfor_nexthops(fi);
396
397                 /* all nexthops are packed in a nested attribute */
398                 payload += nla_total_size((fi->fib_nhs * nhsize) +
399                                           nh_encapsize);
400
401         }
402
403         return payload;
404 }
405
406 void rtmsg_fib(int event, __be32 key, struct fib_alias *fa,
407                int dst_len, u32 tb_id, const struct nl_info *info,
408                unsigned int nlm_flags)
409 {
410         struct sk_buff *skb;
411         u32 seq = info->nlh ? info->nlh->nlmsg_seq : 0;
412         int err = -ENOBUFS;
413
414         skb = nlmsg_new(fib_nlmsg_size(fa->fa_info), GFP_KERNEL);
415         if (!skb)
416                 goto errout;
417
418         err = fib_dump_info(skb, info->portid, seq, event, tb_id,
419                             fa->fa_type, key, dst_len,
420                             fa->fa_tos, fa->fa_info, nlm_flags);
421         if (err < 0) {
422                 /* -EMSGSIZE implies BUG in fib_nlmsg_size() */
423                 WARN_ON(err == -EMSGSIZE);
424                 kfree_skb(skb);
425                 goto errout;
426         }
427         rtnl_notify(skb, info->nl_net, info->portid, RTNLGRP_IPV4_ROUTE,
428                     info->nlh, GFP_KERNEL);
429         return;
430 errout:
431         if (err < 0)
432                 rtnl_set_sk_err(info->nl_net, RTNLGRP_IPV4_ROUTE, err);
433 }
434
435 static int fib_detect_death(struct fib_info *fi, int order,
436                             struct fib_info **last_resort, int *last_idx,
437                             int dflt)
438 {
439         struct neighbour *n;
440         int state = NUD_NONE;
441
442         n = neigh_lookup(&arp_tbl, &fi->fib_nh[0].nh_gw, fi->fib_dev);
443         if (n) {
444                 state = n->nud_state;
445                 neigh_release(n);
446         } else {
447                 return 0;
448         }
449         if (state == NUD_REACHABLE)
450                 return 0;
451         if ((state & NUD_VALID) && order != dflt)
452                 return 0;
453         if ((state & NUD_VALID) ||
454             (*last_idx < 0 && order > dflt && state != NUD_INCOMPLETE)) {
455                 *last_resort = fi;
456                 *last_idx = order;
457         }
458         return 1;
459 }
460
461 #ifdef CONFIG_IP_ROUTE_MULTIPATH
462
463 static int fib_count_nexthops(struct rtnexthop *rtnh, int remaining,
464                               struct netlink_ext_ack *extack)
465 {
466         int nhs = 0;
467
468         while (rtnh_ok(rtnh, remaining)) {
469                 nhs++;
470                 rtnh = rtnh_next(rtnh, &remaining);
471         }
472
473         /* leftover implies invalid nexthop configuration, discard it */
474         if (remaining > 0) {
475                 NL_SET_ERR_MSG(extack,
476                                "Invalid nexthop configuration - extra data after nexthops");
477                 nhs = 0;
478         }
479
480         return nhs;
481 }
482
483 static int fib_get_nhs(struct fib_info *fi, struct rtnexthop *rtnh,
484                        int remaining, struct fib_config *cfg,
485                        struct netlink_ext_ack *extack)
486 {
487         int ret;
488
489         change_nexthops(fi) {
490                 int attrlen;
491
492                 if (!rtnh_ok(rtnh, remaining)) {
493                         NL_SET_ERR_MSG(extack,
494                                        "Invalid nexthop configuration - extra data after nexthop");
495                         return -EINVAL;
496                 }
497
498                 if (rtnh->rtnh_flags & (RTNH_F_DEAD | RTNH_F_LINKDOWN)) {
499                         NL_SET_ERR_MSG(extack,
500                                        "Invalid flags for nexthop - can not contain DEAD or LINKDOWN");
501                         return -EINVAL;
502                 }
503
504                 nexthop_nh->nh_flags =
505                         (cfg->fc_flags & ~0xFF) | rtnh->rtnh_flags;
506                 nexthop_nh->nh_oif = rtnh->rtnh_ifindex;
507                 nexthop_nh->nh_weight = rtnh->rtnh_hops + 1;
508
509                 attrlen = rtnh_attrlen(rtnh);
510                 if (attrlen > 0) {
511                         struct nlattr *nla, *attrs = rtnh_attrs(rtnh);
512
513                         nla = nla_find(attrs, attrlen, RTA_GATEWAY);
514                         nexthop_nh->nh_gw = nla ? nla_get_in_addr(nla) : 0;
515 #ifdef CONFIG_IP_ROUTE_CLASSID
516                         nla = nla_find(attrs, attrlen, RTA_FLOW);
517                         nexthop_nh->nh_tclassid = nla ? nla_get_u32(nla) : 0;
518                         if (nexthop_nh->nh_tclassid)
519                                 fi->fib_net->ipv4.fib_num_tclassid_users++;
520 #endif
521                         nla = nla_find(attrs, attrlen, RTA_ENCAP);
522                         if (nla) {
523                                 struct lwtunnel_state *lwtstate;
524                                 struct nlattr *nla_entype;
525
526                                 nla_entype = nla_find(attrs, attrlen,
527                                                       RTA_ENCAP_TYPE);
528                                 if (!nla_entype) {
529                                         NL_SET_BAD_ATTR(extack, nla);
530                                         NL_SET_ERR_MSG(extack,
531                                                        "Encap type is missing");
532                                         goto err_inval;
533                                 }
534
535                                 ret = lwtunnel_build_state(nla_get_u16(
536                                                            nla_entype),
537                                                            nla,  AF_INET, cfg,
538                                                            &lwtstate, extack);
539                                 if (ret)
540                                         goto errout;
541                                 nexthop_nh->nh_lwtstate =
542                                         lwtstate_get(lwtstate);
543                         }
544                 }
545
546                 rtnh = rtnh_next(rtnh, &remaining);
547         } endfor_nexthops(fi);
548
549         return 0;
550
551 err_inval:
552         ret = -EINVAL;
553
554 errout:
555         return ret;
556 }
557
558 static void fib_rebalance(struct fib_info *fi)
559 {
560         int total;
561         int w;
562         struct in_device *in_dev;
563
564         if (fi->fib_nhs < 2)
565                 return;
566
567         total = 0;
568         for_nexthops(fi) {
569                 if (nh->nh_flags & RTNH_F_DEAD)
570                         continue;
571
572                 in_dev = __in_dev_get_rtnl(nh->nh_dev);
573
574                 if (in_dev &&
575                     IN_DEV_IGNORE_ROUTES_WITH_LINKDOWN(in_dev) &&
576                     nh->nh_flags & RTNH_F_LINKDOWN)
577                         continue;
578
579                 total += nh->nh_weight;
580         } endfor_nexthops(fi);
581
582         w = 0;
583         change_nexthops(fi) {
584                 int upper_bound;
585
586                 in_dev = __in_dev_get_rtnl(nexthop_nh->nh_dev);
587
588                 if (nexthop_nh->nh_flags & RTNH_F_DEAD) {
589                         upper_bound = -1;
590                 } else if (in_dev &&
591                            IN_DEV_IGNORE_ROUTES_WITH_LINKDOWN(in_dev) &&
592                            nexthop_nh->nh_flags & RTNH_F_LINKDOWN) {
593                         upper_bound = -1;
594                 } else {
595                         w += nexthop_nh->nh_weight;
596                         upper_bound = DIV_ROUND_CLOSEST_ULL((u64)w << 31,
597                                                             total) - 1;
598                 }
599
600                 atomic_set(&nexthop_nh->nh_upper_bound, upper_bound);
601         } endfor_nexthops(fi);
602 }
603
604 static inline void fib_add_weight(struct fib_info *fi,
605                                   const struct fib_nh *nh)
606 {
607         fi->fib_weight += nh->nh_weight;
608 }
609
610 #else /* CONFIG_IP_ROUTE_MULTIPATH */
611
612 #define fib_rebalance(fi) do { } while (0)
613 #define fib_add_weight(fi, nh) do { } while (0)
614
615 #endif /* CONFIG_IP_ROUTE_MULTIPATH */
616
617 static int fib_encap_match(u16 encap_type,
618                            struct nlattr *encap,
619                            const struct fib_nh *nh,
620                            const struct fib_config *cfg,
621                            struct netlink_ext_ack *extack)
622 {
623         struct lwtunnel_state *lwtstate;
624         int ret, result = 0;
625
626         if (encap_type == LWTUNNEL_ENCAP_NONE)
627                 return 0;
628
629         ret = lwtunnel_build_state(encap_type, encap, AF_INET,
630                                    cfg, &lwtstate, extack);
631         if (!ret) {
632                 result = lwtunnel_cmp_encap(lwtstate, nh->nh_lwtstate);
633                 lwtstate_free(lwtstate);
634         }
635
636         return result;
637 }
638
639 int fib_nh_match(struct fib_config *cfg, struct fib_info *fi,
640                  struct netlink_ext_ack *extack)
641 {
642 #ifdef CONFIG_IP_ROUTE_MULTIPATH
643         struct rtnexthop *rtnh;
644         int remaining;
645 #endif
646
647         if (cfg->fc_priority && cfg->fc_priority != fi->fib_priority)
648                 return 1;
649
650         if (cfg->fc_oif || cfg->fc_gw) {
651                 if (cfg->fc_encap) {
652                         if (fib_encap_match(cfg->fc_encap_type, cfg->fc_encap,
653                                             fi->fib_nh, cfg, extack))
654                                 return 1;
655                 }
656                 if ((!cfg->fc_oif || cfg->fc_oif == fi->fib_nh->nh_oif) &&
657                     (!cfg->fc_gw  || cfg->fc_gw == fi->fib_nh->nh_gw))
658                         return 0;
659                 return 1;
660         }
661
662 #ifdef CONFIG_IP_ROUTE_MULTIPATH
663         if (!cfg->fc_mp)
664                 return 0;
665
666         rtnh = cfg->fc_mp;
667         remaining = cfg->fc_mp_len;
668
669         for_nexthops(fi) {
670                 int attrlen;
671
672                 if (!rtnh_ok(rtnh, remaining))
673                         return -EINVAL;
674
675                 if (rtnh->rtnh_ifindex && rtnh->rtnh_ifindex != nh->nh_oif)
676                         return 1;
677
678                 attrlen = rtnh_attrlen(rtnh);
679                 if (attrlen > 0) {
680                         struct nlattr *nla, *attrs = rtnh_attrs(rtnh);
681
682                         nla = nla_find(attrs, attrlen, RTA_GATEWAY);
683                         if (nla && nla_get_in_addr(nla) != nh->nh_gw)
684                                 return 1;
685 #ifdef CONFIG_IP_ROUTE_CLASSID
686                         nla = nla_find(attrs, attrlen, RTA_FLOW);
687                         if (nla && nla_get_u32(nla) != nh->nh_tclassid)
688                                 return 1;
689 #endif
690                 }
691
692                 rtnh = rtnh_next(rtnh, &remaining);
693         } endfor_nexthops(fi);
694 #endif
695         return 0;
696 }
697
698
699 /*
700  * Picture
701  * -------
702  *
703  * Semantics of nexthop is very messy by historical reasons.
704  * We have to take into account, that:
705  * a) gateway can be actually local interface address,
706  *    so that gatewayed route is direct.
707  * b) gateway must be on-link address, possibly
708  *    described not by an ifaddr, but also by a direct route.
709  * c) If both gateway and interface are specified, they should not
710  *    contradict.
711  * d) If we use tunnel routes, gateway could be not on-link.
712  *
713  * Attempt to reconcile all of these (alas, self-contradictory) conditions
714  * results in pretty ugly and hairy code with obscure logic.
715  *
716  * I chose to generalized it instead, so that the size
717  * of code does not increase practically, but it becomes
718  * much more general.
719  * Every prefix is assigned a "scope" value: "host" is local address,
720  * "link" is direct route,
721  * [ ... "site" ... "interior" ... ]
722  * and "universe" is true gateway route with global meaning.
723  *
724  * Every prefix refers to a set of "nexthop"s (gw, oif),
725  * where gw must have narrower scope. This recursion stops
726  * when gw has LOCAL scope or if "nexthop" is declared ONLINK,
727  * which means that gw is forced to be on link.
728  *
729  * Code is still hairy, but now it is apparently logically
730  * consistent and very flexible. F.e. as by-product it allows
731  * to co-exists in peace independent exterior and interior
732  * routing processes.
733  *
734  * Normally it looks as following.
735  *
736  * {universe prefix}  -> (gw, oif) [scope link]
737  *                |
738  *                |-> {link prefix} -> (gw, oif) [scope local]
739  *                                      |
740  *                                      |-> {local prefix} (terminal node)
741  */
742 static int fib_check_nh(struct fib_config *cfg, struct fib_info *fi,
743                         struct fib_nh *nh, struct netlink_ext_ack *extack)
744 {
745         int err = 0;
746         struct net *net;
747         struct net_device *dev;
748
749         net = cfg->fc_nlinfo.nl_net;
750         if (nh->nh_gw) {
751                 struct fib_result res;
752
753                 if (nh->nh_flags & RTNH_F_ONLINK) {
754                         unsigned int addr_type;
755
756                         if (cfg->fc_scope >= RT_SCOPE_LINK) {
757                                 NL_SET_ERR_MSG(extack,
758                                                "Nexthop has invalid scope");
759                                 return -EINVAL;
760                         }
761                         dev = __dev_get_by_index(net, nh->nh_oif);
762                         if (!dev)
763                                 return -ENODEV;
764                         if (!(dev->flags & IFF_UP)) {
765                                 NL_SET_ERR_MSG(extack,
766                                                "Nexthop device is not up");
767                                 return -ENETDOWN;
768                         }
769                         addr_type = inet_addr_type_dev_table(net, dev, nh->nh_gw);
770                         if (addr_type != RTN_UNICAST) {
771                                 NL_SET_ERR_MSG(extack,
772                                                "Nexthop has invalid gateway");
773                                 return -EINVAL;
774                         }
775                         if (!netif_carrier_ok(dev))
776                                 nh->nh_flags |= RTNH_F_LINKDOWN;
777                         nh->nh_dev = dev;
778                         dev_hold(dev);
779                         nh->nh_scope = RT_SCOPE_LINK;
780                         return 0;
781                 }
782                 rcu_read_lock();
783                 {
784                         struct fib_table *tbl = NULL;
785                         struct flowi4 fl4 = {
786                                 .daddr = nh->nh_gw,
787                                 .flowi4_scope = cfg->fc_scope + 1,
788                                 .flowi4_oif = nh->nh_oif,
789                                 .flowi4_iif = LOOPBACK_IFINDEX,
790                         };
791
792                         /* It is not necessary, but requires a bit of thinking */
793                         if (fl4.flowi4_scope < RT_SCOPE_LINK)
794                                 fl4.flowi4_scope = RT_SCOPE_LINK;
795
796                         if (cfg->fc_table)
797                                 tbl = fib_get_table(net, cfg->fc_table);
798
799                         if (tbl)
800                                 err = fib_table_lookup(tbl, &fl4, &res,
801                                                        FIB_LOOKUP_IGNORE_LINKSTATE |
802                                                        FIB_LOOKUP_NOREF);
803
804                         /* on error or if no table given do full lookup. This
805                          * is needed for example when nexthops are in the local
806                          * table rather than the given table
807                          */
808                         if (!tbl || err) {
809                                 err = fib_lookup(net, &fl4, &res,
810                                                  FIB_LOOKUP_IGNORE_LINKSTATE);
811                         }
812
813                         if (err) {
814                                 NL_SET_ERR_MSG(extack,
815                                                "Nexthop has invalid gateway");
816                                 rcu_read_unlock();
817                                 return err;
818                         }
819                 }
820                 err = -EINVAL;
821                 if (res.type != RTN_UNICAST && res.type != RTN_LOCAL) {
822                         NL_SET_ERR_MSG(extack, "Nexthop has invalid gateway");
823                         goto out;
824                 }
825                 nh->nh_scope = res.scope;
826                 nh->nh_oif = FIB_RES_OIF(res);
827                 nh->nh_dev = dev = FIB_RES_DEV(res);
828                 if (!dev) {
829                         NL_SET_ERR_MSG(extack,
830                                        "No egress device for nexthop gateway");
831                         goto out;
832                 }
833                 dev_hold(dev);
834                 if (!netif_carrier_ok(dev))
835                         nh->nh_flags |= RTNH_F_LINKDOWN;
836                 err = (dev->flags & IFF_UP) ? 0 : -ENETDOWN;
837         } else {
838                 struct in_device *in_dev;
839
840                 if (nh->nh_flags & (RTNH_F_PERVASIVE | RTNH_F_ONLINK)) {
841                         NL_SET_ERR_MSG(extack,
842                                        "Invalid flags for nexthop - PERVASIVE and ONLINK can not be set");
843                         return -EINVAL;
844                 }
845                 rcu_read_lock();
846                 err = -ENODEV;
847                 in_dev = inetdev_by_index(net, nh->nh_oif);
848                 if (!in_dev)
849                         goto out;
850                 err = -ENETDOWN;
851                 if (!(in_dev->dev->flags & IFF_UP)) {
852                         NL_SET_ERR_MSG(extack, "Device for nexthop is not up");
853                         goto out;
854                 }
855                 nh->nh_dev = in_dev->dev;
856                 dev_hold(nh->nh_dev);
857                 nh->nh_scope = RT_SCOPE_HOST;
858                 if (!netif_carrier_ok(nh->nh_dev))
859                         nh->nh_flags |= RTNH_F_LINKDOWN;
860                 err = 0;
861         }
862 out:
863         rcu_read_unlock();
864         return err;
865 }
866
867 static inline unsigned int fib_laddr_hashfn(__be32 val)
868 {
869         unsigned int mask = (fib_info_hash_size - 1);
870
871         return ((__force u32)val ^
872                 ((__force u32)val >> 7) ^
873                 ((__force u32)val >> 14)) & mask;
874 }
875
876 static struct hlist_head *fib_info_hash_alloc(int bytes)
877 {
878         if (bytes <= PAGE_SIZE)
879                 return kzalloc(bytes, GFP_KERNEL);
880         else
881                 return (struct hlist_head *)
882                         __get_free_pages(GFP_KERNEL | __GFP_ZERO,
883                                          get_order(bytes));
884 }
885
886 static void fib_info_hash_free(struct hlist_head *hash, int bytes)
887 {
888         if (!hash)
889                 return;
890
891         if (bytes <= PAGE_SIZE)
892                 kfree(hash);
893         else
894                 free_pages((unsigned long) hash, get_order(bytes));
895 }
896
897 static void fib_info_hash_move(struct hlist_head *new_info_hash,
898                                struct hlist_head *new_laddrhash,
899                                unsigned int new_size)
900 {
901         struct hlist_head *old_info_hash, *old_laddrhash;
902         unsigned int old_size = fib_info_hash_size;
903         unsigned int i, bytes;
904
905         spin_lock_bh(&fib_info_lock);
906         old_info_hash = fib_info_hash;
907         old_laddrhash = fib_info_laddrhash;
908         fib_info_hash_size = new_size;
909
910         for (i = 0; i < old_size; i++) {
911                 struct hlist_head *head = &fib_info_hash[i];
912                 struct hlist_node *n;
913                 struct fib_info *fi;
914
915                 hlist_for_each_entry_safe(fi, n, head, fib_hash) {
916                         struct hlist_head *dest;
917                         unsigned int new_hash;
918
919                         new_hash = fib_info_hashfn(fi);
920                         dest = &new_info_hash[new_hash];
921                         hlist_add_head(&fi->fib_hash, dest);
922                 }
923         }
924         fib_info_hash = new_info_hash;
925
926         for (i = 0; i < old_size; i++) {
927                 struct hlist_head *lhead = &fib_info_laddrhash[i];
928                 struct hlist_node *n;
929                 struct fib_info *fi;
930
931                 hlist_for_each_entry_safe(fi, n, lhead, fib_lhash) {
932                         struct hlist_head *ldest;
933                         unsigned int new_hash;
934
935                         new_hash = fib_laddr_hashfn(fi->fib_prefsrc);
936                         ldest = &new_laddrhash[new_hash];
937                         hlist_add_head(&fi->fib_lhash, ldest);
938                 }
939         }
940         fib_info_laddrhash = new_laddrhash;
941
942         spin_unlock_bh(&fib_info_lock);
943
944         bytes = old_size * sizeof(struct hlist_head *);
945         fib_info_hash_free(old_info_hash, bytes);
946         fib_info_hash_free(old_laddrhash, bytes);
947 }
948
949 __be32 fib_info_update_nh_saddr(struct net *net, struct fib_nh *nh)
950 {
951         nh->nh_saddr = inet_select_addr(nh->nh_dev,
952                                         nh->nh_gw,
953                                         nh->nh_parent->fib_scope);
954         nh->nh_saddr_genid = atomic_read(&net->ipv4.dev_addr_genid);
955
956         return nh->nh_saddr;
957 }
958
959 static bool fib_valid_prefsrc(struct fib_config *cfg, __be32 fib_prefsrc)
960 {
961         if (cfg->fc_type != RTN_LOCAL || !cfg->fc_dst ||
962             fib_prefsrc != cfg->fc_dst) {
963                 u32 tb_id = cfg->fc_table;
964                 int rc;
965
966                 if (tb_id == RT_TABLE_MAIN)
967                         tb_id = RT_TABLE_LOCAL;
968
969                 rc = inet_addr_type_table(cfg->fc_nlinfo.nl_net,
970                                           fib_prefsrc, tb_id);
971
972                 if (rc != RTN_LOCAL && tb_id != RT_TABLE_LOCAL) {
973                         rc = inet_addr_type_table(cfg->fc_nlinfo.nl_net,
974                                                   fib_prefsrc, RT_TABLE_LOCAL);
975                 }
976
977                 if (rc != RTN_LOCAL)
978                         return false;
979         }
980         return true;
981 }
982
983 static int
984 fib_convert_metrics(struct fib_info *fi, const struct fib_config *cfg)
985 {
986         bool ecn_ca = false;
987         struct nlattr *nla;
988         int remaining;
989
990         if (!cfg->fc_mx)
991                 return 0;
992
993         nla_for_each_attr(nla, cfg->fc_mx, cfg->fc_mx_len, remaining) {
994                 int type = nla_type(nla);
995                 u32 val;
996
997                 if (!type)
998                         continue;
999                 if (type > RTAX_MAX)
1000                         return -EINVAL;
1001
1002                 if (type == RTAX_CC_ALGO) {
1003                         char tmp[TCP_CA_NAME_MAX];
1004
1005                         nla_strlcpy(tmp, nla, sizeof(tmp));
1006                         val = tcp_ca_get_key_by_name(tmp, &ecn_ca);
1007                         if (val == TCP_CA_UNSPEC)
1008                                 return -EINVAL;
1009                 } else {
1010                         val = nla_get_u32(nla);
1011                 }
1012                 if (type == RTAX_ADVMSS && val > 65535 - 40)
1013                         val = 65535 - 40;
1014                 if (type == RTAX_MTU && val > 65535 - 15)
1015                         val = 65535 - 15;
1016                 if (type == RTAX_HOPLIMIT && val > 255)
1017                         val = 255;
1018                 if (type == RTAX_FEATURES && (val & ~RTAX_FEATURE_MASK))
1019                         return -EINVAL;
1020                 fi->fib_metrics->metrics[type - 1] = val;
1021         }
1022
1023         if (ecn_ca)
1024                 fi->fib_metrics->metrics[RTAX_FEATURES - 1] |= DST_FEATURE_ECN_CA;
1025
1026         return 0;
1027 }
1028
1029 struct fib_info *fib_create_info(struct fib_config *cfg,
1030                                  struct netlink_ext_ack *extack)
1031 {
1032         int err;
1033         struct fib_info *fi = NULL;
1034         struct fib_info *ofi;
1035         int nhs = 1;
1036         struct net *net = cfg->fc_nlinfo.nl_net;
1037
1038         if (cfg->fc_type > RTN_MAX)
1039                 goto err_inval;
1040
1041         /* Fast check to catch the most weird cases */
1042         if (fib_props[cfg->fc_type].scope > cfg->fc_scope) {
1043                 NL_SET_ERR_MSG(extack, "Invalid scope");
1044                 goto err_inval;
1045         }
1046
1047         if (cfg->fc_flags & (RTNH_F_DEAD | RTNH_F_LINKDOWN)) {
1048                 NL_SET_ERR_MSG(extack,
1049                                "Invalid rtm_flags - can not contain DEAD or LINKDOWN");
1050                 goto err_inval;
1051         }
1052
1053 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1054         if (cfg->fc_mp) {
1055                 nhs = fib_count_nexthops(cfg->fc_mp, cfg->fc_mp_len, extack);
1056                 if (nhs == 0)
1057                         goto err_inval;
1058         }
1059 #endif
1060
1061         err = -ENOBUFS;
1062         if (fib_info_cnt >= fib_info_hash_size) {
1063                 unsigned int new_size = fib_info_hash_size << 1;
1064                 struct hlist_head *new_info_hash;
1065                 struct hlist_head *new_laddrhash;
1066                 unsigned int bytes;
1067
1068                 if (!new_size)
1069                         new_size = 16;
1070                 bytes = new_size * sizeof(struct hlist_head *);
1071                 new_info_hash = fib_info_hash_alloc(bytes);
1072                 new_laddrhash = fib_info_hash_alloc(bytes);
1073                 if (!new_info_hash || !new_laddrhash) {
1074                         fib_info_hash_free(new_info_hash, bytes);
1075                         fib_info_hash_free(new_laddrhash, bytes);
1076                 } else
1077                         fib_info_hash_move(new_info_hash, new_laddrhash, new_size);
1078
1079                 if (!fib_info_hash_size)
1080                         goto failure;
1081         }
1082
1083         fi = kzalloc(sizeof(*fi)+nhs*sizeof(struct fib_nh), GFP_KERNEL);
1084         if (!fi)
1085                 goto failure;
1086         if (cfg->fc_mx) {
1087                 fi->fib_metrics = kzalloc(sizeof(*fi->fib_metrics), GFP_KERNEL);
1088                 if (unlikely(!fi->fib_metrics)) {
1089                         kfree(fi);
1090                         return ERR_PTR(err);
1091                 }
1092                 atomic_set(&fi->fib_metrics->refcnt, 1);
1093         } else {
1094                 fi->fib_metrics = (struct dst_metrics *)&dst_default_metrics;
1095         }
1096         fib_info_cnt++;
1097         fi->fib_net = net;
1098         fi->fib_protocol = cfg->fc_protocol;
1099         fi->fib_scope = cfg->fc_scope;
1100         fi->fib_flags = cfg->fc_flags;
1101         fi->fib_priority = cfg->fc_priority;
1102         fi->fib_prefsrc = cfg->fc_prefsrc;
1103         fi->fib_type = cfg->fc_type;
1104         fi->fib_tb_id = cfg->fc_table;
1105
1106         fi->fib_nhs = nhs;
1107         change_nexthops(fi) {
1108                 nexthop_nh->nh_parent = fi;
1109                 nexthop_nh->nh_pcpu_rth_output = alloc_percpu(struct rtable __rcu *);
1110                 if (!nexthop_nh->nh_pcpu_rth_output)
1111                         goto failure;
1112         } endfor_nexthops(fi)
1113
1114         err = fib_convert_metrics(fi, cfg);
1115         if (err)
1116                 goto failure;
1117
1118         if (cfg->fc_mp) {
1119 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1120                 err = fib_get_nhs(fi, cfg->fc_mp, cfg->fc_mp_len, cfg, extack);
1121                 if (err != 0)
1122                         goto failure;
1123                 if (cfg->fc_oif && fi->fib_nh->nh_oif != cfg->fc_oif) {
1124                         NL_SET_ERR_MSG(extack,
1125                                        "Nexthop device index does not match RTA_OIF");
1126                         goto err_inval;
1127                 }
1128                 if (cfg->fc_gw && fi->fib_nh->nh_gw != cfg->fc_gw) {
1129                         NL_SET_ERR_MSG(extack,
1130                                        "Nexthop gateway does not match RTA_GATEWAY");
1131                         goto err_inval;
1132                 }
1133 #ifdef CONFIG_IP_ROUTE_CLASSID
1134                 if (cfg->fc_flow && fi->fib_nh->nh_tclassid != cfg->fc_flow) {
1135                         NL_SET_ERR_MSG(extack,
1136                                        "Nexthop class id does not match RTA_FLOW");
1137                         goto err_inval;
1138                 }
1139 #endif
1140 #else
1141                 NL_SET_ERR_MSG(extack,
1142                                "Multipath support not enabled in kernel");
1143                 goto err_inval;
1144 #endif
1145         } else {
1146                 struct fib_nh *nh = fi->fib_nh;
1147
1148                 if (cfg->fc_encap) {
1149                         struct lwtunnel_state *lwtstate;
1150
1151                         if (cfg->fc_encap_type == LWTUNNEL_ENCAP_NONE) {
1152                                 NL_SET_ERR_MSG(extack,
1153                                                "LWT encap type not specified");
1154                                 goto err_inval;
1155                         }
1156                         err = lwtunnel_build_state(cfg->fc_encap_type,
1157                                                    cfg->fc_encap, AF_INET, cfg,
1158                                                    &lwtstate, extack);
1159                         if (err)
1160                                 goto failure;
1161
1162                         nh->nh_lwtstate = lwtstate_get(lwtstate);
1163                 }
1164                 nh->nh_oif = cfg->fc_oif;
1165                 nh->nh_gw = cfg->fc_gw;
1166                 nh->nh_flags = cfg->fc_flags;
1167 #ifdef CONFIG_IP_ROUTE_CLASSID
1168                 nh->nh_tclassid = cfg->fc_flow;
1169                 if (nh->nh_tclassid)
1170                         fi->fib_net->ipv4.fib_num_tclassid_users++;
1171 #endif
1172 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1173                 nh->nh_weight = 1;
1174 #endif
1175         }
1176
1177         if (fib_props[cfg->fc_type].error) {
1178                 if (cfg->fc_gw || cfg->fc_oif || cfg->fc_mp) {
1179                         NL_SET_ERR_MSG(extack,
1180                                        "Gateway, device and multipath can not be specified for this route type");
1181                         goto err_inval;
1182                 }
1183                 goto link_it;
1184         } else {
1185                 switch (cfg->fc_type) {
1186                 case RTN_UNICAST:
1187                 case RTN_LOCAL:
1188                 case RTN_BROADCAST:
1189                 case RTN_ANYCAST:
1190                 case RTN_MULTICAST:
1191                         break;
1192                 default:
1193                         NL_SET_ERR_MSG(extack, "Invalid route type");
1194                         goto err_inval;
1195                 }
1196         }
1197
1198         if (cfg->fc_scope > RT_SCOPE_HOST) {
1199                 NL_SET_ERR_MSG(extack, "Invalid scope");
1200                 goto err_inval;
1201         }
1202
1203         if (cfg->fc_scope == RT_SCOPE_HOST) {
1204                 struct fib_nh *nh = fi->fib_nh;
1205
1206                 /* Local address is added. */
1207                 if (nhs != 1) {
1208                         NL_SET_ERR_MSG(extack,
1209                                        "Route with host scope can not have multiple nexthops");
1210                         goto err_inval;
1211                 }
1212                 if (nh->nh_gw) {
1213                         NL_SET_ERR_MSG(extack,
1214                                        "Route with host scope can not have a gateway");
1215                         goto err_inval;
1216                 }
1217                 nh->nh_scope = RT_SCOPE_NOWHERE;
1218                 nh->nh_dev = dev_get_by_index(net, fi->fib_nh->nh_oif);
1219                 err = -ENODEV;
1220                 if (!nh->nh_dev)
1221                         goto failure;
1222         } else {
1223                 int linkdown = 0;
1224
1225                 change_nexthops(fi) {
1226                         err = fib_check_nh(cfg, fi, nexthop_nh, extack);
1227                         if (err != 0)
1228                                 goto failure;
1229                         if (nexthop_nh->nh_flags & RTNH_F_LINKDOWN)
1230                                 linkdown++;
1231                 } endfor_nexthops(fi)
1232                 if (linkdown == fi->fib_nhs)
1233                         fi->fib_flags |= RTNH_F_LINKDOWN;
1234         }
1235
1236         if (fi->fib_prefsrc && !fib_valid_prefsrc(cfg, fi->fib_prefsrc)) {
1237                 NL_SET_ERR_MSG(extack, "Invalid prefsrc address");
1238                 goto err_inval;
1239         }
1240
1241         change_nexthops(fi) {
1242                 fib_info_update_nh_saddr(net, nexthop_nh);
1243                 fib_add_weight(fi, nexthop_nh);
1244         } endfor_nexthops(fi)
1245
1246         fib_rebalance(fi);
1247
1248 link_it:
1249         ofi = fib_find_info(fi);
1250         if (ofi) {
1251                 fi->fib_dead = 1;
1252                 free_fib_info(fi);
1253                 ofi->fib_treeref++;
1254                 return ofi;
1255         }
1256
1257         fi->fib_treeref++;
1258         refcount_set(&fi->fib_clntref, 1);
1259         spin_lock_bh(&fib_info_lock);
1260         hlist_add_head(&fi->fib_hash,
1261                        &fib_info_hash[fib_info_hashfn(fi)]);
1262         if (fi->fib_prefsrc) {
1263                 struct hlist_head *head;
1264
1265                 head = &fib_info_laddrhash[fib_laddr_hashfn(fi->fib_prefsrc)];
1266                 hlist_add_head(&fi->fib_lhash, head);
1267         }
1268         change_nexthops(fi) {
1269                 struct hlist_head *head;
1270                 unsigned int hash;
1271
1272                 if (!nexthop_nh->nh_dev)
1273                         continue;
1274                 hash = fib_devindex_hashfn(nexthop_nh->nh_dev->ifindex);
1275                 head = &fib_info_devhash[hash];
1276                 hlist_add_head(&nexthop_nh->nh_hash, head);
1277         } endfor_nexthops(fi)
1278         spin_unlock_bh(&fib_info_lock);
1279         return fi;
1280
1281 err_inval:
1282         err = -EINVAL;
1283
1284 failure:
1285         if (fi) {
1286                 fi->fib_dead = 1;
1287                 free_fib_info(fi);
1288         }
1289
1290         return ERR_PTR(err);
1291 }
1292
1293 int fib_dump_info(struct sk_buff *skb, u32 portid, u32 seq, int event,
1294                   u32 tb_id, u8 type, __be32 dst, int dst_len, u8 tos,
1295                   struct fib_info *fi, unsigned int flags)
1296 {
1297         struct nlmsghdr *nlh;
1298         struct rtmsg *rtm;
1299
1300         nlh = nlmsg_put(skb, portid, seq, event, sizeof(*rtm), flags);
1301         if (!nlh)
1302                 return -EMSGSIZE;
1303
1304         rtm = nlmsg_data(nlh);
1305         rtm->rtm_family = AF_INET;
1306         rtm->rtm_dst_len = dst_len;
1307         rtm->rtm_src_len = 0;
1308         rtm->rtm_tos = tos;
1309         if (tb_id < 256)
1310                 rtm->rtm_table = tb_id;
1311         else
1312                 rtm->rtm_table = RT_TABLE_COMPAT;
1313         if (nla_put_u32(skb, RTA_TABLE, tb_id))
1314                 goto nla_put_failure;
1315         rtm->rtm_type = type;
1316         rtm->rtm_flags = fi->fib_flags;
1317         rtm->rtm_scope = fi->fib_scope;
1318         rtm->rtm_protocol = fi->fib_protocol;
1319
1320         if (rtm->rtm_dst_len &&
1321             nla_put_in_addr(skb, RTA_DST, dst))
1322                 goto nla_put_failure;
1323         if (fi->fib_priority &&
1324             nla_put_u32(skb, RTA_PRIORITY, fi->fib_priority))
1325                 goto nla_put_failure;
1326         if (rtnetlink_put_metrics(skb, fi->fib_metrics->metrics) < 0)
1327                 goto nla_put_failure;
1328
1329         if (fi->fib_prefsrc &&
1330             nla_put_in_addr(skb, RTA_PREFSRC, fi->fib_prefsrc))
1331                 goto nla_put_failure;
1332         if (fi->fib_nhs == 1) {
1333                 struct in_device *in_dev;
1334
1335                 if (fi->fib_nh->nh_gw &&
1336                     nla_put_in_addr(skb, RTA_GATEWAY, fi->fib_nh->nh_gw))
1337                         goto nla_put_failure;
1338                 if (fi->fib_nh->nh_oif &&
1339                     nla_put_u32(skb, RTA_OIF, fi->fib_nh->nh_oif))
1340                         goto nla_put_failure;
1341                 if (fi->fib_nh->nh_flags & RTNH_F_LINKDOWN) {
1342                         in_dev = __in_dev_get_rtnl(fi->fib_nh->nh_dev);
1343                         if (in_dev &&
1344                             IN_DEV_IGNORE_ROUTES_WITH_LINKDOWN(in_dev))
1345                                 rtm->rtm_flags |= RTNH_F_DEAD;
1346                 }
1347 #ifdef CONFIG_IP_ROUTE_CLASSID
1348                 if (fi->fib_nh[0].nh_tclassid &&
1349                     nla_put_u32(skb, RTA_FLOW, fi->fib_nh[0].nh_tclassid))
1350                         goto nla_put_failure;
1351 #endif
1352                 if (fi->fib_nh->nh_lwtstate &&
1353                     lwtunnel_fill_encap(skb, fi->fib_nh->nh_lwtstate) < 0)
1354                         goto nla_put_failure;
1355         }
1356 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1357         if (fi->fib_nhs > 1) {
1358                 struct rtnexthop *rtnh;
1359                 struct nlattr *mp;
1360
1361                 mp = nla_nest_start(skb, RTA_MULTIPATH);
1362                 if (!mp)
1363                         goto nla_put_failure;
1364
1365                 for_nexthops(fi) {
1366                         struct in_device *in_dev;
1367
1368                         rtnh = nla_reserve_nohdr(skb, sizeof(*rtnh));
1369                         if (!rtnh)
1370                                 goto nla_put_failure;
1371
1372                         rtnh->rtnh_flags = nh->nh_flags & 0xFF;
1373                         if (nh->nh_flags & RTNH_F_LINKDOWN) {
1374                                 in_dev = __in_dev_get_rtnl(nh->nh_dev);
1375                                 if (in_dev &&
1376                                     IN_DEV_IGNORE_ROUTES_WITH_LINKDOWN(in_dev))
1377                                         rtnh->rtnh_flags |= RTNH_F_DEAD;
1378                         }
1379                         rtnh->rtnh_hops = nh->nh_weight - 1;
1380                         rtnh->rtnh_ifindex = nh->nh_oif;
1381
1382                         if (nh->nh_gw &&
1383                             nla_put_in_addr(skb, RTA_GATEWAY, nh->nh_gw))
1384                                 goto nla_put_failure;
1385 #ifdef CONFIG_IP_ROUTE_CLASSID
1386                         if (nh->nh_tclassid &&
1387                             nla_put_u32(skb, RTA_FLOW, nh->nh_tclassid))
1388                                 goto nla_put_failure;
1389 #endif
1390                         if (nh->nh_lwtstate &&
1391                             lwtunnel_fill_encap(skb, nh->nh_lwtstate) < 0)
1392                                 goto nla_put_failure;
1393
1394                         /* length of rtnetlink header + attributes */
1395                         rtnh->rtnh_len = nlmsg_get_pos(skb) - (void *) rtnh;
1396                 } endfor_nexthops(fi);
1397
1398                 nla_nest_end(skb, mp);
1399         }
1400 #endif
1401         nlmsg_end(skb, nlh);
1402         return 0;
1403
1404 nla_put_failure:
1405         nlmsg_cancel(skb, nlh);
1406         return -EMSGSIZE;
1407 }
1408
1409 /*
1410  * Update FIB if:
1411  * - local address disappeared -> we must delete all the entries
1412  *   referring to it.
1413  * - device went down -> we must shutdown all nexthops going via it.
1414  */
1415 int fib_sync_down_addr(struct net_device *dev, __be32 local)
1416 {
1417         int ret = 0;
1418         unsigned int hash = fib_laddr_hashfn(local);
1419         struct hlist_head *head = &fib_info_laddrhash[hash];
1420         struct net *net = dev_net(dev);
1421         int tb_id = l3mdev_fib_table(dev);
1422         struct fib_info *fi;
1423
1424         if (!fib_info_laddrhash || local == 0)
1425                 return 0;
1426
1427         hlist_for_each_entry(fi, head, fib_lhash) {
1428                 if (!net_eq(fi->fib_net, net) ||
1429                     fi->fib_tb_id != tb_id)
1430                         continue;
1431                 if (fi->fib_prefsrc == local) {
1432                         fi->fib_flags |= RTNH_F_DEAD;
1433                         ret++;
1434                 }
1435         }
1436         return ret;
1437 }
1438
1439 static int call_fib_nh_notifiers(struct fib_nh *fib_nh,
1440                                  enum fib_event_type event_type)
1441 {
1442         struct in_device *in_dev = __in_dev_get_rtnl(fib_nh->nh_dev);
1443         struct fib_nh_notifier_info info = {
1444                 .fib_nh = fib_nh,
1445         };
1446
1447         switch (event_type) {
1448         case FIB_EVENT_NH_ADD:
1449                 if (fib_nh->nh_flags & RTNH_F_DEAD)
1450                         break;
1451                 if (IN_DEV_IGNORE_ROUTES_WITH_LINKDOWN(in_dev) &&
1452                     fib_nh->nh_flags & RTNH_F_LINKDOWN)
1453                         break;
1454                 return call_fib_notifiers(dev_net(fib_nh->nh_dev), event_type,
1455                                           &info.info);
1456         case FIB_EVENT_NH_DEL:
1457                 if ((in_dev && IN_DEV_IGNORE_ROUTES_WITH_LINKDOWN(in_dev) &&
1458                      fib_nh->nh_flags & RTNH_F_LINKDOWN) ||
1459                     (fib_nh->nh_flags & RTNH_F_DEAD))
1460                         return call_fib_notifiers(dev_net(fib_nh->nh_dev),
1461                                                   event_type, &info.info);
1462         default:
1463                 break;
1464         }
1465
1466         return NOTIFY_DONE;
1467 }
1468
1469 /* Event              force Flags           Description
1470  * NETDEV_CHANGE      0     LINKDOWN        Carrier OFF, not for scope host
1471  * NETDEV_DOWN        0     LINKDOWN|DEAD   Link down, not for scope host
1472  * NETDEV_DOWN        1     LINKDOWN|DEAD   Last address removed
1473  * NETDEV_UNREGISTER  1     LINKDOWN|DEAD   Device removed
1474  */
1475 int fib_sync_down_dev(struct net_device *dev, unsigned long event, bool force)
1476 {
1477         int ret = 0;
1478         int scope = RT_SCOPE_NOWHERE;
1479         struct fib_info *prev_fi = NULL;
1480         unsigned int hash = fib_devindex_hashfn(dev->ifindex);
1481         struct hlist_head *head = &fib_info_devhash[hash];
1482         struct fib_nh *nh;
1483
1484         if (force)
1485                 scope = -1;
1486
1487         hlist_for_each_entry(nh, head, nh_hash) {
1488                 struct fib_info *fi = nh->nh_parent;
1489                 int dead;
1490
1491                 BUG_ON(!fi->fib_nhs);
1492                 if (nh->nh_dev != dev || fi == prev_fi)
1493                         continue;
1494                 prev_fi = fi;
1495                 dead = 0;
1496                 change_nexthops(fi) {
1497                         if (nexthop_nh->nh_flags & RTNH_F_DEAD)
1498                                 dead++;
1499                         else if (nexthop_nh->nh_dev == dev &&
1500                                  nexthop_nh->nh_scope != scope) {
1501                                 switch (event) {
1502                                 case NETDEV_DOWN:
1503                                 case NETDEV_UNREGISTER:
1504                                         nexthop_nh->nh_flags |= RTNH_F_DEAD;
1505                                         /* fall through */
1506                                 case NETDEV_CHANGE:
1507                                         nexthop_nh->nh_flags |= RTNH_F_LINKDOWN;
1508                                         break;
1509                                 }
1510                                 call_fib_nh_notifiers(nexthop_nh,
1511                                                       FIB_EVENT_NH_DEL);
1512                                 dead++;
1513                         }
1514 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1515                         if (event == NETDEV_UNREGISTER &&
1516                             nexthop_nh->nh_dev == dev) {
1517                                 dead = fi->fib_nhs;
1518                                 break;
1519                         }
1520 #endif
1521                 } endfor_nexthops(fi)
1522                 if (dead == fi->fib_nhs) {
1523                         switch (event) {
1524                         case NETDEV_DOWN:
1525                         case NETDEV_UNREGISTER:
1526                                 fi->fib_flags |= RTNH_F_DEAD;
1527                                 /* fall through */
1528                         case NETDEV_CHANGE:
1529                                 fi->fib_flags |= RTNH_F_LINKDOWN;
1530                                 break;
1531                         }
1532                         ret++;
1533                 }
1534
1535                 fib_rebalance(fi);
1536         }
1537
1538         return ret;
1539 }
1540
1541 /* Must be invoked inside of an RCU protected region.  */
1542 static void fib_select_default(const struct flowi4 *flp, struct fib_result *res)
1543 {
1544         struct fib_info *fi = NULL, *last_resort = NULL;
1545         struct hlist_head *fa_head = res->fa_head;
1546         struct fib_table *tb = res->table;
1547         u8 slen = 32 - res->prefixlen;
1548         int order = -1, last_idx = -1;
1549         struct fib_alias *fa, *fa1 = NULL;
1550         u32 last_prio = res->fi->fib_priority;
1551         u8 last_tos = 0;
1552
1553         hlist_for_each_entry_rcu(fa, fa_head, fa_list) {
1554                 struct fib_info *next_fi = fa->fa_info;
1555
1556                 if (fa->fa_slen != slen)
1557                         continue;
1558                 if (fa->fa_tos && fa->fa_tos != flp->flowi4_tos)
1559                         continue;
1560                 if (fa->tb_id != tb->tb_id)
1561                         continue;
1562                 if (next_fi->fib_priority > last_prio &&
1563                     fa->fa_tos == last_tos) {
1564                         if (last_tos)
1565                                 continue;
1566                         break;
1567                 }
1568                 if (next_fi->fib_flags & RTNH_F_DEAD)
1569                         continue;
1570                 last_tos = fa->fa_tos;
1571                 last_prio = next_fi->fib_priority;
1572
1573                 if (next_fi->fib_scope != res->scope ||
1574                     fa->fa_type != RTN_UNICAST)
1575                         continue;
1576                 if (!next_fi->fib_nh[0].nh_gw ||
1577                     next_fi->fib_nh[0].nh_scope != RT_SCOPE_LINK)
1578                         continue;
1579
1580                 fib_alias_accessed(fa);
1581
1582                 if (!fi) {
1583                         if (next_fi != res->fi)
1584                                 break;
1585                         fa1 = fa;
1586                 } else if (!fib_detect_death(fi, order, &last_resort,
1587                                              &last_idx, fa1->fa_default)) {
1588                         fib_result_assign(res, fi);
1589                         fa1->fa_default = order;
1590                         goto out;
1591                 }
1592                 fi = next_fi;
1593                 order++;
1594         }
1595
1596         if (order <= 0 || !fi) {
1597                 if (fa1)
1598                         fa1->fa_default = -1;
1599                 goto out;
1600         }
1601
1602         if (!fib_detect_death(fi, order, &last_resort, &last_idx,
1603                               fa1->fa_default)) {
1604                 fib_result_assign(res, fi);
1605                 fa1->fa_default = order;
1606                 goto out;
1607         }
1608
1609         if (last_idx >= 0)
1610                 fib_result_assign(res, last_resort);
1611         fa1->fa_default = last_idx;
1612 out:
1613         return;
1614 }
1615
1616 /*
1617  * Dead device goes up. We wake up dead nexthops.
1618  * It takes sense only on multipath routes.
1619  */
1620 int fib_sync_up(struct net_device *dev, unsigned int nh_flags)
1621 {
1622         struct fib_info *prev_fi;
1623         unsigned int hash;
1624         struct hlist_head *head;
1625         struct fib_nh *nh;
1626         int ret;
1627
1628         if (!(dev->flags & IFF_UP))
1629                 return 0;
1630
1631         if (nh_flags & RTNH_F_DEAD) {
1632                 unsigned int flags = dev_get_flags(dev);
1633
1634                 if (flags & (IFF_RUNNING | IFF_LOWER_UP))
1635                         nh_flags |= RTNH_F_LINKDOWN;
1636         }
1637
1638         prev_fi = NULL;
1639         hash = fib_devindex_hashfn(dev->ifindex);
1640         head = &fib_info_devhash[hash];
1641         ret = 0;
1642
1643         hlist_for_each_entry(nh, head, nh_hash) {
1644                 struct fib_info *fi = nh->nh_parent;
1645                 int alive;
1646
1647                 BUG_ON(!fi->fib_nhs);
1648                 if (nh->nh_dev != dev || fi == prev_fi)
1649                         continue;
1650
1651                 prev_fi = fi;
1652                 alive = 0;
1653                 change_nexthops(fi) {
1654                         if (!(nexthop_nh->nh_flags & nh_flags)) {
1655                                 alive++;
1656                                 continue;
1657                         }
1658                         if (!nexthop_nh->nh_dev ||
1659                             !(nexthop_nh->nh_dev->flags & IFF_UP))
1660                                 continue;
1661                         if (nexthop_nh->nh_dev != dev ||
1662                             !__in_dev_get_rtnl(dev))
1663                                 continue;
1664                         alive++;
1665                         nexthop_nh->nh_flags &= ~nh_flags;
1666                         call_fib_nh_notifiers(nexthop_nh, FIB_EVENT_NH_ADD);
1667                 } endfor_nexthops(fi)
1668
1669                 if (alive > 0) {
1670                         fi->fib_flags &= ~nh_flags;
1671                         ret++;
1672                 }
1673
1674                 fib_rebalance(fi);
1675         }
1676
1677         return ret;
1678 }
1679
1680 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1681 static bool fib_good_nh(const struct fib_nh *nh)
1682 {
1683         int state = NUD_REACHABLE;
1684
1685         if (nh->nh_scope == RT_SCOPE_LINK) {
1686                 struct neighbour *n;
1687
1688                 rcu_read_lock_bh();
1689
1690                 n = __ipv4_neigh_lookup_noref(nh->nh_dev,
1691                                               (__force u32)nh->nh_gw);
1692                 if (n)
1693                         state = n->nud_state;
1694
1695                 rcu_read_unlock_bh();
1696         }
1697
1698         return !!(state & NUD_VALID);
1699 }
1700
1701 void fib_select_multipath(struct fib_result *res, int hash)
1702 {
1703         struct fib_info *fi = res->fi;
1704         struct net *net = fi->fib_net;
1705         bool first = false;
1706
1707         for_nexthops(fi) {
1708                 if (hash > atomic_read(&nh->nh_upper_bound))
1709                         continue;
1710
1711                 if (!net->ipv4.sysctl_fib_multipath_use_neigh ||
1712                     fib_good_nh(nh)) {
1713                         res->nh_sel = nhsel;
1714                         return;
1715                 }
1716                 if (!first) {
1717                         res->nh_sel = nhsel;
1718                         first = true;
1719                 }
1720         } endfor_nexthops(fi);
1721 }
1722 #endif
1723
1724 void fib_select_path(struct net *net, struct fib_result *res,
1725                      struct flowi4 *fl4, const struct sk_buff *skb)
1726 {
1727         bool oif_check;
1728
1729         oif_check = (fl4->flowi4_oif == 0 ||
1730                      fl4->flowi4_flags & FLOWI_FLAG_SKIP_NH_OIF);
1731
1732 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1733         if (res->fi->fib_nhs > 1 && oif_check) {
1734                 int h = fib_multipath_hash(res->fi, fl4, skb);
1735
1736                 fib_select_multipath(res, h);
1737         }
1738         else
1739 #endif
1740         if (!res->prefixlen &&
1741             res->table->tb_num_default > 1 &&
1742             res->type == RTN_UNICAST && oif_check)
1743                 fib_select_default(fl4, res);
1744
1745         if (!fl4->saddr)
1746                 fl4->saddr = FIB_RES_PREFSRC(net, *res);
1747 }
1748 EXPORT_SYMBOL_GPL(fib_select_path);