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vfio/pci: Fix typos in comments
[deliverable/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 <asm/uaccess.h>
17 #include <linux/bitops.h>
18 #include <linux/types.h>
19 #include <linux/kernel.h>
20 #include <linux/jiffies.h>
21 #include <linux/mm.h>
22 #include <linux/string.h>
23 #include <linux/socket.h>
24 #include <linux/sockios.h>
25 #include <linux/errno.h>
26 #include <linux/in.h>
27 #include <linux/inet.h>
28 #include <linux/inetdevice.h>
29 #include <linux/netdevice.h>
30 #include <linux/if_arp.h>
31 #include <linux/proc_fs.h>
32 #include <linux/skbuff.h>
33 #include <linux/init.h>
34 #include <linux/slab.h>
35
36 #include <net/arp.h>
37 #include <net/ip.h>
38 #include <net/protocol.h>
39 #include <net/route.h>
40 #include <net/tcp.h>
41 #include <net/sock.h>
42 #include <net/ip_fib.h>
43 #include <net/netlink.h>
44 #include <net/nexthop.h>
45 #include <net/lwtunnel.h>
46
47 #include "fib_lookup.h"
48
49 static DEFINE_SPINLOCK(fib_info_lock);
50 static struct hlist_head *fib_info_hash;
51 static struct hlist_head *fib_info_laddrhash;
52 static unsigned int fib_info_hash_size;
53 static unsigned int fib_info_cnt;
54
55 #define DEVINDEX_HASHBITS 8
56 #define DEVINDEX_HASHSIZE (1U << DEVINDEX_HASHBITS)
57 static struct hlist_head fib_info_devhash[DEVINDEX_HASHSIZE];
58
59 #ifdef CONFIG_IP_ROUTE_MULTIPATH
60 u32 fib_multipath_secret __read_mostly;
61
62 #define for_nexthops(fi) { \
63 int nhsel; const struct fib_nh *nh; \
64 for (nhsel = 0, nh = (fi)->fib_nh; \
65 nhsel < (fi)->fib_nhs; \
66 nh++, nhsel++)
67
68 #define change_nexthops(fi) { \
69 int nhsel; struct fib_nh *nexthop_nh; \
70 for (nhsel = 0, nexthop_nh = (struct fib_nh *)((fi)->fib_nh); \
71 nhsel < (fi)->fib_nhs; \
72 nexthop_nh++, nhsel++)
73
74 #else /* CONFIG_IP_ROUTE_MULTIPATH */
75
76 /* Hope, that gcc will optimize it to get rid of dummy loop */
77
78 #define for_nexthops(fi) { \
79 int nhsel; const struct fib_nh *nh = (fi)->fib_nh; \
80 for (nhsel = 0; nhsel < 1; nhsel++)
81
82 #define change_nexthops(fi) { \
83 int nhsel; \
84 struct fib_nh *nexthop_nh = (struct fib_nh *)((fi)->fib_nh); \
85 for (nhsel = 0; nhsel < 1; nhsel++)
86
87 #endif /* CONFIG_IP_ROUTE_MULTIPATH */
88
89 #define endfor_nexthops(fi) }
90
91
92 const struct fib_prop fib_props[RTN_MAX + 1] = {
93 [RTN_UNSPEC] = {
94 .error = 0,
95 .scope = RT_SCOPE_NOWHERE,
96 },
97 [RTN_UNICAST] = {
98 .error = 0,
99 .scope = RT_SCOPE_UNIVERSE,
100 },
101 [RTN_LOCAL] = {
102 .error = 0,
103 .scope = RT_SCOPE_HOST,
104 },
105 [RTN_BROADCAST] = {
106 .error = 0,
107 .scope = RT_SCOPE_LINK,
108 },
109 [RTN_ANYCAST] = {
110 .error = 0,
111 .scope = RT_SCOPE_LINK,
112 },
113 [RTN_MULTICAST] = {
114 .error = 0,
115 .scope = RT_SCOPE_UNIVERSE,
116 },
117 [RTN_BLACKHOLE] = {
118 .error = -EINVAL,
119 .scope = RT_SCOPE_UNIVERSE,
120 },
121 [RTN_UNREACHABLE] = {
122 .error = -EHOSTUNREACH,
123 .scope = RT_SCOPE_UNIVERSE,
124 },
125 [RTN_PROHIBIT] = {
126 .error = -EACCES,
127 .scope = RT_SCOPE_UNIVERSE,
128 },
129 [RTN_THROW] = {
130 .error = -EAGAIN,
131 .scope = RT_SCOPE_UNIVERSE,
132 },
133 [RTN_NAT] = {
134 .error = -EINVAL,
135 .scope = RT_SCOPE_NOWHERE,
136 },
137 [RTN_XRESOLVE] = {
138 .error = -EINVAL,
139 .scope = RT_SCOPE_NOWHERE,
140 },
141 };
142
143 static void rt_fibinfo_free(struct rtable __rcu **rtp)
144 {
145 struct rtable *rt = rcu_dereference_protected(*rtp, 1);
146
147 if (!rt)
148 return;
149
150 /* Not even needed : RCU_INIT_POINTER(*rtp, NULL);
151 * because we waited an RCU grace period before calling
152 * free_fib_info_rcu()
153 */
154
155 dst_free(&rt->dst);
156 }
157
158 static void free_nh_exceptions(struct fib_nh *nh)
159 {
160 struct fnhe_hash_bucket *hash;
161 int i;
162
163 hash = rcu_dereference_protected(nh->nh_exceptions, 1);
164 if (!hash)
165 return;
166 for (i = 0; i < FNHE_HASH_SIZE; i++) {
167 struct fib_nh_exception *fnhe;
168
169 fnhe = rcu_dereference_protected(hash[i].chain, 1);
170 while (fnhe) {
171 struct fib_nh_exception *next;
172
173 next = rcu_dereference_protected(fnhe->fnhe_next, 1);
174
175 rt_fibinfo_free(&fnhe->fnhe_rth_input);
176 rt_fibinfo_free(&fnhe->fnhe_rth_output);
177
178 kfree(fnhe);
179
180 fnhe = next;
181 }
182 }
183 kfree(hash);
184 }
185
186 static void rt_fibinfo_free_cpus(struct rtable __rcu * __percpu *rtp)
187 {
188 int cpu;
189
190 if (!rtp)
191 return;
192
193 for_each_possible_cpu(cpu) {
194 struct rtable *rt;
195
196 rt = rcu_dereference_protected(*per_cpu_ptr(rtp, cpu), 1);
197 if (rt)
198 dst_free(&rt->dst);
199 }
200 free_percpu(rtp);
201 }
202
203 /* Release a nexthop info record */
204 static void free_fib_info_rcu(struct rcu_head *head)
205 {
206 struct fib_info *fi = container_of(head, struct fib_info, rcu);
207
208 change_nexthops(fi) {
209 if (nexthop_nh->nh_dev)
210 dev_put(nexthop_nh->nh_dev);
211 lwtstate_put(nexthop_nh->nh_lwtstate);
212 free_nh_exceptions(nexthop_nh);
213 rt_fibinfo_free_cpus(nexthop_nh->nh_pcpu_rth_output);
214 rt_fibinfo_free(&nexthop_nh->nh_rth_input);
215 } endfor_nexthops(fi);
216
217 if (fi->fib_metrics != (u32 *) dst_default_metrics)
218 kfree(fi->fib_metrics);
219 kfree(fi);
220 }
221
222 void free_fib_info(struct fib_info *fi)
223 {
224 if (fi->fib_dead == 0) {
225 pr_warn("Freeing alive fib_info %p\n", fi);
226 return;
227 }
228 fib_info_cnt--;
229 #ifdef CONFIG_IP_ROUTE_CLASSID
230 change_nexthops(fi) {
231 if (nexthop_nh->nh_tclassid)
232 fi->fib_net->ipv4.fib_num_tclassid_users--;
233 } endfor_nexthops(fi);
234 #endif
235 call_rcu(&fi->rcu, free_fib_info_rcu);
236 }
237
238 void fib_release_info(struct fib_info *fi)
239 {
240 spin_lock_bh(&fib_info_lock);
241 if (fi && --fi->fib_treeref == 0) {
242 hlist_del(&fi->fib_hash);
243 if (fi->fib_prefsrc)
244 hlist_del(&fi->fib_lhash);
245 change_nexthops(fi) {
246 if (!nexthop_nh->nh_dev)
247 continue;
248 hlist_del(&nexthop_nh->nh_hash);
249 } endfor_nexthops(fi)
250 fi->fib_dead = 1;
251 fib_info_put(fi);
252 }
253 spin_unlock_bh(&fib_info_lock);
254 }
255
256 static inline int nh_comp(const struct fib_info *fi, const struct fib_info *ofi)
257 {
258 const struct fib_nh *onh = ofi->fib_nh;
259
260 for_nexthops(fi) {
261 if (nh->nh_oif != onh->nh_oif ||
262 nh->nh_gw != onh->nh_gw ||
263 nh->nh_scope != onh->nh_scope ||
264 #ifdef CONFIG_IP_ROUTE_MULTIPATH
265 nh->nh_weight != onh->nh_weight ||
266 #endif
267 #ifdef CONFIG_IP_ROUTE_CLASSID
268 nh->nh_tclassid != onh->nh_tclassid ||
269 #endif
270 lwtunnel_cmp_encap(nh->nh_lwtstate, onh->nh_lwtstate) ||
271 ((nh->nh_flags ^ onh->nh_flags) & ~RTNH_COMPARE_MASK))
272 return -1;
273 onh++;
274 } endfor_nexthops(fi);
275 return 0;
276 }
277
278 static inline unsigned int fib_devindex_hashfn(unsigned int val)
279 {
280 unsigned int mask = DEVINDEX_HASHSIZE - 1;
281
282 return (val ^
283 (val >> DEVINDEX_HASHBITS) ^
284 (val >> (DEVINDEX_HASHBITS * 2))) & mask;
285 }
286
287 static inline unsigned int fib_info_hashfn(const struct fib_info *fi)
288 {
289 unsigned int mask = (fib_info_hash_size - 1);
290 unsigned int val = fi->fib_nhs;
291
292 val ^= (fi->fib_protocol << 8) | fi->fib_scope;
293 val ^= (__force u32)fi->fib_prefsrc;
294 val ^= fi->fib_priority;
295 for_nexthops(fi) {
296 val ^= fib_devindex_hashfn(nh->nh_oif);
297 } endfor_nexthops(fi)
298
299 return (val ^ (val >> 7) ^ (val >> 12)) & mask;
300 }
301
302 static struct fib_info *fib_find_info(const struct fib_info *nfi)
303 {
304 struct hlist_head *head;
305 struct fib_info *fi;
306 unsigned int hash;
307
308 hash = fib_info_hashfn(nfi);
309 head = &fib_info_hash[hash];
310
311 hlist_for_each_entry(fi, head, fib_hash) {
312 if (!net_eq(fi->fib_net, nfi->fib_net))
313 continue;
314 if (fi->fib_nhs != nfi->fib_nhs)
315 continue;
316 if (nfi->fib_protocol == fi->fib_protocol &&
317 nfi->fib_scope == fi->fib_scope &&
318 nfi->fib_prefsrc == fi->fib_prefsrc &&
319 nfi->fib_priority == fi->fib_priority &&
320 nfi->fib_type == fi->fib_type &&
321 memcmp(nfi->fib_metrics, fi->fib_metrics,
322 sizeof(u32) * RTAX_MAX) == 0 &&
323 !((nfi->fib_flags ^ fi->fib_flags) & ~RTNH_COMPARE_MASK) &&
324 (nfi->fib_nhs == 0 || nh_comp(fi, nfi) == 0))
325 return fi;
326 }
327
328 return NULL;
329 }
330
331 /* Check, that the gateway is already configured.
332 * Used only by redirect accept routine.
333 */
334 int ip_fib_check_default(__be32 gw, struct net_device *dev)
335 {
336 struct hlist_head *head;
337 struct fib_nh *nh;
338 unsigned int hash;
339
340 spin_lock(&fib_info_lock);
341
342 hash = fib_devindex_hashfn(dev->ifindex);
343 head = &fib_info_devhash[hash];
344 hlist_for_each_entry(nh, head, nh_hash) {
345 if (nh->nh_dev == dev &&
346 nh->nh_gw == gw &&
347 !(nh->nh_flags & RTNH_F_DEAD)) {
348 spin_unlock(&fib_info_lock);
349 return 0;
350 }
351 }
352
353 spin_unlock(&fib_info_lock);
354
355 return -1;
356 }
357
358 static inline size_t fib_nlmsg_size(struct fib_info *fi)
359 {
360 size_t payload = NLMSG_ALIGN(sizeof(struct rtmsg))
361 + nla_total_size(4) /* RTA_TABLE */
362 + nla_total_size(4) /* RTA_DST */
363 + nla_total_size(4) /* RTA_PRIORITY */
364 + nla_total_size(4) /* RTA_PREFSRC */
365 + nla_total_size(TCP_CA_NAME_MAX); /* RTAX_CC_ALGO */
366
367 /* space for nested metrics */
368 payload += nla_total_size((RTAX_MAX * nla_total_size(4)));
369
370 if (fi->fib_nhs) {
371 size_t nh_encapsize = 0;
372 /* Also handles the special case fib_nhs == 1 */
373
374 /* each nexthop is packed in an attribute */
375 size_t nhsize = nla_total_size(sizeof(struct rtnexthop));
376
377 /* may contain flow and gateway attribute */
378 nhsize += 2 * nla_total_size(4);
379
380 /* grab encap info */
381 for_nexthops(fi) {
382 if (nh->nh_lwtstate) {
383 /* RTA_ENCAP_TYPE */
384 nh_encapsize += lwtunnel_get_encap_size(
385 nh->nh_lwtstate);
386 /* RTA_ENCAP */
387 nh_encapsize += nla_total_size(2);
388 }
389 } endfor_nexthops(fi);
390
391 /* all nexthops are packed in a nested attribute */
392 payload += nla_total_size((fi->fib_nhs * nhsize) +
393 nh_encapsize);
394
395 }
396
397 return payload;
398 }
399
400 void rtmsg_fib(int event, __be32 key, struct fib_alias *fa,
401 int dst_len, u32 tb_id, const struct nl_info *info,
402 unsigned int nlm_flags)
403 {
404 struct sk_buff *skb;
405 u32 seq = info->nlh ? info->nlh->nlmsg_seq : 0;
406 int err = -ENOBUFS;
407
408 skb = nlmsg_new(fib_nlmsg_size(fa->fa_info), GFP_KERNEL);
409 if (!skb)
410 goto errout;
411
412 err = fib_dump_info(skb, info->portid, seq, event, tb_id,
413 fa->fa_type, key, dst_len,
414 fa->fa_tos, fa->fa_info, nlm_flags);
415 if (err < 0) {
416 /* -EMSGSIZE implies BUG in fib_nlmsg_size() */
417 WARN_ON(err == -EMSGSIZE);
418 kfree_skb(skb);
419 goto errout;
420 }
421 rtnl_notify(skb, info->nl_net, info->portid, RTNLGRP_IPV4_ROUTE,
422 info->nlh, GFP_KERNEL);
423 return;
424 errout:
425 if (err < 0)
426 rtnl_set_sk_err(info->nl_net, RTNLGRP_IPV4_ROUTE, err);
427 }
428
429 static int fib_detect_death(struct fib_info *fi, int order,
430 struct fib_info **last_resort, int *last_idx,
431 int dflt)
432 {
433 struct neighbour *n;
434 int state = NUD_NONE;
435
436 n = neigh_lookup(&arp_tbl, &fi->fib_nh[0].nh_gw, fi->fib_dev);
437 if (n) {
438 state = n->nud_state;
439 neigh_release(n);
440 } else {
441 return 0;
442 }
443 if (state == NUD_REACHABLE)
444 return 0;
445 if ((state & NUD_VALID) && order != dflt)
446 return 0;
447 if ((state & NUD_VALID) ||
448 (*last_idx < 0 && order > dflt && state != NUD_INCOMPLETE)) {
449 *last_resort = fi;
450 *last_idx = order;
451 }
452 return 1;
453 }
454
455 #ifdef CONFIG_IP_ROUTE_MULTIPATH
456
457 static int fib_count_nexthops(struct rtnexthop *rtnh, int remaining)
458 {
459 int nhs = 0;
460
461 while (rtnh_ok(rtnh, remaining)) {
462 nhs++;
463 rtnh = rtnh_next(rtnh, &remaining);
464 }
465
466 /* leftover implies invalid nexthop configuration, discard it */
467 return remaining > 0 ? 0 : nhs;
468 }
469
470 static int fib_get_nhs(struct fib_info *fi, struct rtnexthop *rtnh,
471 int remaining, struct fib_config *cfg)
472 {
473 struct net *net = cfg->fc_nlinfo.nl_net;
474 int ret;
475
476 change_nexthops(fi) {
477 int attrlen;
478
479 if (!rtnh_ok(rtnh, remaining))
480 return -EINVAL;
481
482 if (rtnh->rtnh_flags & (RTNH_F_DEAD | RTNH_F_LINKDOWN))
483 return -EINVAL;
484
485 nexthop_nh->nh_flags =
486 (cfg->fc_flags & ~0xFF) | rtnh->rtnh_flags;
487 nexthop_nh->nh_oif = rtnh->rtnh_ifindex;
488 nexthop_nh->nh_weight = rtnh->rtnh_hops + 1;
489
490 attrlen = rtnh_attrlen(rtnh);
491 if (attrlen > 0) {
492 struct nlattr *nla, *attrs = rtnh_attrs(rtnh);
493
494 nla = nla_find(attrs, attrlen, RTA_GATEWAY);
495 nexthop_nh->nh_gw = nla ? nla_get_in_addr(nla) : 0;
496 #ifdef CONFIG_IP_ROUTE_CLASSID
497 nla = nla_find(attrs, attrlen, RTA_FLOW);
498 nexthop_nh->nh_tclassid = nla ? nla_get_u32(nla) : 0;
499 if (nexthop_nh->nh_tclassid)
500 fi->fib_net->ipv4.fib_num_tclassid_users++;
501 #endif
502 nla = nla_find(attrs, attrlen, RTA_ENCAP);
503 if (nla) {
504 struct lwtunnel_state *lwtstate;
505 struct net_device *dev = NULL;
506 struct nlattr *nla_entype;
507
508 nla_entype = nla_find(attrs, attrlen,
509 RTA_ENCAP_TYPE);
510 if (!nla_entype)
511 goto err_inval;
512 if (cfg->fc_oif)
513 dev = __dev_get_by_index(net, cfg->fc_oif);
514 ret = lwtunnel_build_state(dev, nla_get_u16(
515 nla_entype),
516 nla, AF_INET, cfg,
517 &lwtstate);
518 if (ret)
519 goto errout;
520 nexthop_nh->nh_lwtstate =
521 lwtstate_get(lwtstate);
522 }
523 }
524
525 rtnh = rtnh_next(rtnh, &remaining);
526 } endfor_nexthops(fi);
527
528 return 0;
529
530 err_inval:
531 ret = -EINVAL;
532
533 errout:
534 return ret;
535 }
536
537 static void fib_rebalance(struct fib_info *fi)
538 {
539 int total;
540 int w;
541 struct in_device *in_dev;
542
543 if (fi->fib_nhs < 2)
544 return;
545
546 total = 0;
547 for_nexthops(fi) {
548 if (nh->nh_flags & RTNH_F_DEAD)
549 continue;
550
551 in_dev = __in_dev_get_rtnl(nh->nh_dev);
552
553 if (in_dev &&
554 IN_DEV_IGNORE_ROUTES_WITH_LINKDOWN(in_dev) &&
555 nh->nh_flags & RTNH_F_LINKDOWN)
556 continue;
557
558 total += nh->nh_weight;
559 } endfor_nexthops(fi);
560
561 w = 0;
562 change_nexthops(fi) {
563 int upper_bound;
564
565 in_dev = __in_dev_get_rtnl(nexthop_nh->nh_dev);
566
567 if (nexthop_nh->nh_flags & RTNH_F_DEAD) {
568 upper_bound = -1;
569 } else if (in_dev &&
570 IN_DEV_IGNORE_ROUTES_WITH_LINKDOWN(in_dev) &&
571 nexthop_nh->nh_flags & RTNH_F_LINKDOWN) {
572 upper_bound = -1;
573 } else {
574 w += nexthop_nh->nh_weight;
575 upper_bound = DIV_ROUND_CLOSEST_ULL((u64)w << 31,
576 total) - 1;
577 }
578
579 atomic_set(&nexthop_nh->nh_upper_bound, upper_bound);
580 } endfor_nexthops(fi);
581
582 net_get_random_once(&fib_multipath_secret,
583 sizeof(fib_multipath_secret));
584 }
585
586 static inline void fib_add_weight(struct fib_info *fi,
587 const struct fib_nh *nh)
588 {
589 fi->fib_weight += nh->nh_weight;
590 }
591
592 #else /* CONFIG_IP_ROUTE_MULTIPATH */
593
594 #define fib_rebalance(fi) do { } while (0)
595 #define fib_add_weight(fi, nh) do { } while (0)
596
597 #endif /* CONFIG_IP_ROUTE_MULTIPATH */
598
599 static int fib_encap_match(struct net *net, u16 encap_type,
600 struct nlattr *encap,
601 int oif, const struct fib_nh *nh,
602 const struct fib_config *cfg)
603 {
604 struct lwtunnel_state *lwtstate;
605 struct net_device *dev = NULL;
606 int ret, result = 0;
607
608 if (encap_type == LWTUNNEL_ENCAP_NONE)
609 return 0;
610
611 if (oif)
612 dev = __dev_get_by_index(net, oif);
613 ret = lwtunnel_build_state(dev, encap_type, encap,
614 AF_INET, cfg, &lwtstate);
615 if (!ret) {
616 result = lwtunnel_cmp_encap(lwtstate, nh->nh_lwtstate);
617 lwtstate_free(lwtstate);
618 }
619
620 return result;
621 }
622
623 int fib_nh_match(struct fib_config *cfg, struct fib_info *fi)
624 {
625 struct net *net = cfg->fc_nlinfo.nl_net;
626 #ifdef CONFIG_IP_ROUTE_MULTIPATH
627 struct rtnexthop *rtnh;
628 int remaining;
629 #endif
630
631 if (cfg->fc_priority && cfg->fc_priority != fi->fib_priority)
632 return 1;
633
634 if (cfg->fc_oif || cfg->fc_gw) {
635 if (cfg->fc_encap) {
636 if (fib_encap_match(net, cfg->fc_encap_type,
637 cfg->fc_encap, cfg->fc_oif,
638 fi->fib_nh, cfg))
639 return 1;
640 }
641 if ((!cfg->fc_oif || cfg->fc_oif == fi->fib_nh->nh_oif) &&
642 (!cfg->fc_gw || cfg->fc_gw == fi->fib_nh->nh_gw))
643 return 0;
644 return 1;
645 }
646
647 #ifdef CONFIG_IP_ROUTE_MULTIPATH
648 if (!cfg->fc_mp)
649 return 0;
650
651 rtnh = cfg->fc_mp;
652 remaining = cfg->fc_mp_len;
653
654 for_nexthops(fi) {
655 int attrlen;
656
657 if (!rtnh_ok(rtnh, remaining))
658 return -EINVAL;
659
660 if (rtnh->rtnh_ifindex && rtnh->rtnh_ifindex != nh->nh_oif)
661 return 1;
662
663 attrlen = rtnh_attrlen(rtnh);
664 if (attrlen > 0) {
665 struct nlattr *nla, *attrs = rtnh_attrs(rtnh);
666
667 nla = nla_find(attrs, attrlen, RTA_GATEWAY);
668 if (nla && nla_get_in_addr(nla) != nh->nh_gw)
669 return 1;
670 #ifdef CONFIG_IP_ROUTE_CLASSID
671 nla = nla_find(attrs, attrlen, RTA_FLOW);
672 if (nla && nla_get_u32(nla) != nh->nh_tclassid)
673 return 1;
674 #endif
675 }
676
677 rtnh = rtnh_next(rtnh, &remaining);
678 } endfor_nexthops(fi);
679 #endif
680 return 0;
681 }
682
683
684 /*
685 * Picture
686 * -------
687 *
688 * Semantics of nexthop is very messy by historical reasons.
689 * We have to take into account, that:
690 * a) gateway can be actually local interface address,
691 * so that gatewayed route is direct.
692 * b) gateway must be on-link address, possibly
693 * described not by an ifaddr, but also by a direct route.
694 * c) If both gateway and interface are specified, they should not
695 * contradict.
696 * d) If we use tunnel routes, gateway could be not on-link.
697 *
698 * Attempt to reconcile all of these (alas, self-contradictory) conditions
699 * results in pretty ugly and hairy code with obscure logic.
700 *
701 * I chose to generalized it instead, so that the size
702 * of code does not increase practically, but it becomes
703 * much more general.
704 * Every prefix is assigned a "scope" value: "host" is local address,
705 * "link" is direct route,
706 * [ ... "site" ... "interior" ... ]
707 * and "universe" is true gateway route with global meaning.
708 *
709 * Every prefix refers to a set of "nexthop"s (gw, oif),
710 * where gw must have narrower scope. This recursion stops
711 * when gw has LOCAL scope or if "nexthop" is declared ONLINK,
712 * which means that gw is forced to be on link.
713 *
714 * Code is still hairy, but now it is apparently logically
715 * consistent and very flexible. F.e. as by-product it allows
716 * to co-exists in peace independent exterior and interior
717 * routing processes.
718 *
719 * Normally it looks as following.
720 *
721 * {universe prefix} -> (gw, oif) [scope link]
722 * |
723 * |-> {link prefix} -> (gw, oif) [scope local]
724 * |
725 * |-> {local prefix} (terminal node)
726 */
727 static int fib_check_nh(struct fib_config *cfg, struct fib_info *fi,
728 struct fib_nh *nh)
729 {
730 int err = 0;
731 struct net *net;
732 struct net_device *dev;
733
734 net = cfg->fc_nlinfo.nl_net;
735 if (nh->nh_gw) {
736 struct fib_result res;
737
738 if (nh->nh_flags & RTNH_F_ONLINK) {
739 unsigned int addr_type;
740
741 if (cfg->fc_scope >= RT_SCOPE_LINK)
742 return -EINVAL;
743 dev = __dev_get_by_index(net, nh->nh_oif);
744 if (!dev)
745 return -ENODEV;
746 if (!(dev->flags & IFF_UP))
747 return -ENETDOWN;
748 addr_type = inet_addr_type_dev_table(net, dev, nh->nh_gw);
749 if (addr_type != RTN_UNICAST)
750 return -EINVAL;
751 if (!netif_carrier_ok(dev))
752 nh->nh_flags |= RTNH_F_LINKDOWN;
753 nh->nh_dev = dev;
754 dev_hold(dev);
755 nh->nh_scope = RT_SCOPE_LINK;
756 return 0;
757 }
758 rcu_read_lock();
759 {
760 struct fib_table *tbl = NULL;
761 struct flowi4 fl4 = {
762 .daddr = nh->nh_gw,
763 .flowi4_scope = cfg->fc_scope + 1,
764 .flowi4_oif = nh->nh_oif,
765 .flowi4_iif = LOOPBACK_IFINDEX,
766 };
767
768 /* It is not necessary, but requires a bit of thinking */
769 if (fl4.flowi4_scope < RT_SCOPE_LINK)
770 fl4.flowi4_scope = RT_SCOPE_LINK;
771
772 if (cfg->fc_table)
773 tbl = fib_get_table(net, cfg->fc_table);
774
775 if (tbl)
776 err = fib_table_lookup(tbl, &fl4, &res,
777 FIB_LOOKUP_IGNORE_LINKSTATE |
778 FIB_LOOKUP_NOREF);
779
780 /* on error or if no table given do full lookup. This
781 * is needed for example when nexthops are in the local
782 * table rather than the given table
783 */
784 if (!tbl || err) {
785 err = fib_lookup(net, &fl4, &res,
786 FIB_LOOKUP_IGNORE_LINKSTATE);
787 }
788
789 if (err) {
790 rcu_read_unlock();
791 return err;
792 }
793 }
794 err = -EINVAL;
795 if (res.type != RTN_UNICAST && res.type != RTN_LOCAL)
796 goto out;
797 nh->nh_scope = res.scope;
798 nh->nh_oif = FIB_RES_OIF(res);
799 nh->nh_dev = dev = FIB_RES_DEV(res);
800 if (!dev)
801 goto out;
802 dev_hold(dev);
803 if (!netif_carrier_ok(dev))
804 nh->nh_flags |= RTNH_F_LINKDOWN;
805 err = (dev->flags & IFF_UP) ? 0 : -ENETDOWN;
806 } else {
807 struct in_device *in_dev;
808
809 if (nh->nh_flags & (RTNH_F_PERVASIVE | RTNH_F_ONLINK))
810 return -EINVAL;
811
812 rcu_read_lock();
813 err = -ENODEV;
814 in_dev = inetdev_by_index(net, nh->nh_oif);
815 if (!in_dev)
816 goto out;
817 err = -ENETDOWN;
818 if (!(in_dev->dev->flags & IFF_UP))
819 goto out;
820 nh->nh_dev = in_dev->dev;
821 dev_hold(nh->nh_dev);
822 nh->nh_scope = RT_SCOPE_HOST;
823 if (!netif_carrier_ok(nh->nh_dev))
824 nh->nh_flags |= RTNH_F_LINKDOWN;
825 err = 0;
826 }
827 out:
828 rcu_read_unlock();
829 return err;
830 }
831
832 static inline unsigned int fib_laddr_hashfn(__be32 val)
833 {
834 unsigned int mask = (fib_info_hash_size - 1);
835
836 return ((__force u32)val ^
837 ((__force u32)val >> 7) ^
838 ((__force u32)val >> 14)) & mask;
839 }
840
841 static struct hlist_head *fib_info_hash_alloc(int bytes)
842 {
843 if (bytes <= PAGE_SIZE)
844 return kzalloc(bytes, GFP_KERNEL);
845 else
846 return (struct hlist_head *)
847 __get_free_pages(GFP_KERNEL | __GFP_ZERO,
848 get_order(bytes));
849 }
850
851 static void fib_info_hash_free(struct hlist_head *hash, int bytes)
852 {
853 if (!hash)
854 return;
855
856 if (bytes <= PAGE_SIZE)
857 kfree(hash);
858 else
859 free_pages((unsigned long) hash, get_order(bytes));
860 }
861
862 static void fib_info_hash_move(struct hlist_head *new_info_hash,
863 struct hlist_head *new_laddrhash,
864 unsigned int new_size)
865 {
866 struct hlist_head *old_info_hash, *old_laddrhash;
867 unsigned int old_size = fib_info_hash_size;
868 unsigned int i, bytes;
869
870 spin_lock_bh(&fib_info_lock);
871 old_info_hash = fib_info_hash;
872 old_laddrhash = fib_info_laddrhash;
873 fib_info_hash_size = new_size;
874
875 for (i = 0; i < old_size; i++) {
876 struct hlist_head *head = &fib_info_hash[i];
877 struct hlist_node *n;
878 struct fib_info *fi;
879
880 hlist_for_each_entry_safe(fi, n, head, fib_hash) {
881 struct hlist_head *dest;
882 unsigned int new_hash;
883
884 new_hash = fib_info_hashfn(fi);
885 dest = &new_info_hash[new_hash];
886 hlist_add_head(&fi->fib_hash, dest);
887 }
888 }
889 fib_info_hash = new_info_hash;
890
891 for (i = 0; i < old_size; i++) {
892 struct hlist_head *lhead = &fib_info_laddrhash[i];
893 struct hlist_node *n;
894 struct fib_info *fi;
895
896 hlist_for_each_entry_safe(fi, n, lhead, fib_lhash) {
897 struct hlist_head *ldest;
898 unsigned int new_hash;
899
900 new_hash = fib_laddr_hashfn(fi->fib_prefsrc);
901 ldest = &new_laddrhash[new_hash];
902 hlist_add_head(&fi->fib_lhash, ldest);
903 }
904 }
905 fib_info_laddrhash = new_laddrhash;
906
907 spin_unlock_bh(&fib_info_lock);
908
909 bytes = old_size * sizeof(struct hlist_head *);
910 fib_info_hash_free(old_info_hash, bytes);
911 fib_info_hash_free(old_laddrhash, bytes);
912 }
913
914 __be32 fib_info_update_nh_saddr(struct net *net, struct fib_nh *nh)
915 {
916 nh->nh_saddr = inet_select_addr(nh->nh_dev,
917 nh->nh_gw,
918 nh->nh_parent->fib_scope);
919 nh->nh_saddr_genid = atomic_read(&net->ipv4.dev_addr_genid);
920
921 return nh->nh_saddr;
922 }
923
924 static bool fib_valid_prefsrc(struct fib_config *cfg, __be32 fib_prefsrc)
925 {
926 if (cfg->fc_type != RTN_LOCAL || !cfg->fc_dst ||
927 fib_prefsrc != cfg->fc_dst) {
928 u32 tb_id = cfg->fc_table;
929 int rc;
930
931 if (tb_id == RT_TABLE_MAIN)
932 tb_id = RT_TABLE_LOCAL;
933
934 rc = inet_addr_type_table(cfg->fc_nlinfo.nl_net,
935 fib_prefsrc, tb_id);
936
937 if (rc != RTN_LOCAL && tb_id != RT_TABLE_LOCAL) {
938 rc = inet_addr_type_table(cfg->fc_nlinfo.nl_net,
939 fib_prefsrc, RT_TABLE_LOCAL);
940 }
941
942 if (rc != RTN_LOCAL)
943 return false;
944 }
945 return true;
946 }
947
948 static int
949 fib_convert_metrics(struct fib_info *fi, const struct fib_config *cfg)
950 {
951 bool ecn_ca = false;
952 struct nlattr *nla;
953 int remaining;
954
955 if (!cfg->fc_mx)
956 return 0;
957
958 nla_for_each_attr(nla, cfg->fc_mx, cfg->fc_mx_len, remaining) {
959 int type = nla_type(nla);
960 u32 val;
961
962 if (!type)
963 continue;
964 if (type > RTAX_MAX)
965 return -EINVAL;
966
967 if (type == RTAX_CC_ALGO) {
968 char tmp[TCP_CA_NAME_MAX];
969
970 nla_strlcpy(tmp, nla, sizeof(tmp));
971 val = tcp_ca_get_key_by_name(tmp, &ecn_ca);
972 if (val == TCP_CA_UNSPEC)
973 return -EINVAL;
974 } else {
975 val = nla_get_u32(nla);
976 }
977 if (type == RTAX_ADVMSS && val > 65535 - 40)
978 val = 65535 - 40;
979 if (type == RTAX_MTU && val > 65535 - 15)
980 val = 65535 - 15;
981 if (type == RTAX_HOPLIMIT && val > 255)
982 val = 255;
983 if (type == RTAX_FEATURES && (val & ~RTAX_FEATURE_MASK))
984 return -EINVAL;
985 fi->fib_metrics[type - 1] = val;
986 }
987
988 if (ecn_ca)
989 fi->fib_metrics[RTAX_FEATURES - 1] |= DST_FEATURE_ECN_CA;
990
991 return 0;
992 }
993
994 struct fib_info *fib_create_info(struct fib_config *cfg)
995 {
996 int err;
997 struct fib_info *fi = NULL;
998 struct fib_info *ofi;
999 int nhs = 1;
1000 struct net *net = cfg->fc_nlinfo.nl_net;
1001
1002 if (cfg->fc_type > RTN_MAX)
1003 goto err_inval;
1004
1005 /* Fast check to catch the most weird cases */
1006 if (fib_props[cfg->fc_type].scope > cfg->fc_scope)
1007 goto err_inval;
1008
1009 if (cfg->fc_flags & (RTNH_F_DEAD | RTNH_F_LINKDOWN))
1010 goto err_inval;
1011
1012 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1013 if (cfg->fc_mp) {
1014 nhs = fib_count_nexthops(cfg->fc_mp, cfg->fc_mp_len);
1015 if (nhs == 0)
1016 goto err_inval;
1017 }
1018 #endif
1019
1020 err = -ENOBUFS;
1021 if (fib_info_cnt >= fib_info_hash_size) {
1022 unsigned int new_size = fib_info_hash_size << 1;
1023 struct hlist_head *new_info_hash;
1024 struct hlist_head *new_laddrhash;
1025 unsigned int bytes;
1026
1027 if (!new_size)
1028 new_size = 16;
1029 bytes = new_size * sizeof(struct hlist_head *);
1030 new_info_hash = fib_info_hash_alloc(bytes);
1031 new_laddrhash = fib_info_hash_alloc(bytes);
1032 if (!new_info_hash || !new_laddrhash) {
1033 fib_info_hash_free(new_info_hash, bytes);
1034 fib_info_hash_free(new_laddrhash, bytes);
1035 } else
1036 fib_info_hash_move(new_info_hash, new_laddrhash, new_size);
1037
1038 if (!fib_info_hash_size)
1039 goto failure;
1040 }
1041
1042 fi = kzalloc(sizeof(*fi)+nhs*sizeof(struct fib_nh), GFP_KERNEL);
1043 if (!fi)
1044 goto failure;
1045 fib_info_cnt++;
1046 if (cfg->fc_mx) {
1047 fi->fib_metrics = kzalloc(sizeof(u32) * RTAX_MAX, GFP_KERNEL);
1048 if (!fi->fib_metrics)
1049 goto failure;
1050 } else
1051 fi->fib_metrics = (u32 *) dst_default_metrics;
1052
1053 fi->fib_net = net;
1054 fi->fib_protocol = cfg->fc_protocol;
1055 fi->fib_scope = cfg->fc_scope;
1056 fi->fib_flags = cfg->fc_flags;
1057 fi->fib_priority = cfg->fc_priority;
1058 fi->fib_prefsrc = cfg->fc_prefsrc;
1059 fi->fib_type = cfg->fc_type;
1060
1061 fi->fib_nhs = nhs;
1062 change_nexthops(fi) {
1063 nexthop_nh->nh_parent = fi;
1064 nexthop_nh->nh_pcpu_rth_output = alloc_percpu(struct rtable __rcu *);
1065 if (!nexthop_nh->nh_pcpu_rth_output)
1066 goto failure;
1067 } endfor_nexthops(fi)
1068
1069 err = fib_convert_metrics(fi, cfg);
1070 if (err)
1071 goto failure;
1072
1073 if (cfg->fc_mp) {
1074 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1075 err = fib_get_nhs(fi, cfg->fc_mp, cfg->fc_mp_len, cfg);
1076 if (err != 0)
1077 goto failure;
1078 if (cfg->fc_oif && fi->fib_nh->nh_oif != cfg->fc_oif)
1079 goto err_inval;
1080 if (cfg->fc_gw && fi->fib_nh->nh_gw != cfg->fc_gw)
1081 goto err_inval;
1082 #ifdef CONFIG_IP_ROUTE_CLASSID
1083 if (cfg->fc_flow && fi->fib_nh->nh_tclassid != cfg->fc_flow)
1084 goto err_inval;
1085 #endif
1086 #else
1087 goto err_inval;
1088 #endif
1089 } else {
1090 struct fib_nh *nh = fi->fib_nh;
1091
1092 if (cfg->fc_encap) {
1093 struct lwtunnel_state *lwtstate;
1094 struct net_device *dev = NULL;
1095
1096 if (cfg->fc_encap_type == LWTUNNEL_ENCAP_NONE)
1097 goto err_inval;
1098 if (cfg->fc_oif)
1099 dev = __dev_get_by_index(net, cfg->fc_oif);
1100 err = lwtunnel_build_state(dev, cfg->fc_encap_type,
1101 cfg->fc_encap, AF_INET, cfg,
1102 &lwtstate);
1103 if (err)
1104 goto failure;
1105
1106 nh->nh_lwtstate = lwtstate_get(lwtstate);
1107 }
1108 nh->nh_oif = cfg->fc_oif;
1109 nh->nh_gw = cfg->fc_gw;
1110 nh->nh_flags = cfg->fc_flags;
1111 #ifdef CONFIG_IP_ROUTE_CLASSID
1112 nh->nh_tclassid = cfg->fc_flow;
1113 if (nh->nh_tclassid)
1114 fi->fib_net->ipv4.fib_num_tclassid_users++;
1115 #endif
1116 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1117 nh->nh_weight = 1;
1118 #endif
1119 }
1120
1121 if (fib_props[cfg->fc_type].error) {
1122 if (cfg->fc_gw || cfg->fc_oif || cfg->fc_mp)
1123 goto err_inval;
1124 goto link_it;
1125 } else {
1126 switch (cfg->fc_type) {
1127 case RTN_UNICAST:
1128 case RTN_LOCAL:
1129 case RTN_BROADCAST:
1130 case RTN_ANYCAST:
1131 case RTN_MULTICAST:
1132 break;
1133 default:
1134 goto err_inval;
1135 }
1136 }
1137
1138 if (cfg->fc_scope > RT_SCOPE_HOST)
1139 goto err_inval;
1140
1141 if (cfg->fc_scope == RT_SCOPE_HOST) {
1142 struct fib_nh *nh = fi->fib_nh;
1143
1144 /* Local address is added. */
1145 if (nhs != 1 || nh->nh_gw)
1146 goto err_inval;
1147 nh->nh_scope = RT_SCOPE_NOWHERE;
1148 nh->nh_dev = dev_get_by_index(net, fi->fib_nh->nh_oif);
1149 err = -ENODEV;
1150 if (!nh->nh_dev)
1151 goto failure;
1152 } else {
1153 int linkdown = 0;
1154
1155 change_nexthops(fi) {
1156 err = fib_check_nh(cfg, fi, nexthop_nh);
1157 if (err != 0)
1158 goto failure;
1159 if (nexthop_nh->nh_flags & RTNH_F_LINKDOWN)
1160 linkdown++;
1161 } endfor_nexthops(fi)
1162 if (linkdown == fi->fib_nhs)
1163 fi->fib_flags |= RTNH_F_LINKDOWN;
1164 }
1165
1166 if (fi->fib_prefsrc && !fib_valid_prefsrc(cfg, fi->fib_prefsrc))
1167 goto err_inval;
1168
1169 change_nexthops(fi) {
1170 fib_info_update_nh_saddr(net, nexthop_nh);
1171 fib_add_weight(fi, nexthop_nh);
1172 } endfor_nexthops(fi)
1173
1174 fib_rebalance(fi);
1175
1176 link_it:
1177 ofi = fib_find_info(fi);
1178 if (ofi) {
1179 fi->fib_dead = 1;
1180 free_fib_info(fi);
1181 ofi->fib_treeref++;
1182 return ofi;
1183 }
1184
1185 fi->fib_treeref++;
1186 atomic_inc(&fi->fib_clntref);
1187 spin_lock_bh(&fib_info_lock);
1188 hlist_add_head(&fi->fib_hash,
1189 &fib_info_hash[fib_info_hashfn(fi)]);
1190 if (fi->fib_prefsrc) {
1191 struct hlist_head *head;
1192
1193 head = &fib_info_laddrhash[fib_laddr_hashfn(fi->fib_prefsrc)];
1194 hlist_add_head(&fi->fib_lhash, head);
1195 }
1196 change_nexthops(fi) {
1197 struct hlist_head *head;
1198 unsigned int hash;
1199
1200 if (!nexthop_nh->nh_dev)
1201 continue;
1202 hash = fib_devindex_hashfn(nexthop_nh->nh_dev->ifindex);
1203 head = &fib_info_devhash[hash];
1204 hlist_add_head(&nexthop_nh->nh_hash, head);
1205 } endfor_nexthops(fi)
1206 spin_unlock_bh(&fib_info_lock);
1207 return fi;
1208
1209 err_inval:
1210 err = -EINVAL;
1211
1212 failure:
1213 if (fi) {
1214 fi->fib_dead = 1;
1215 free_fib_info(fi);
1216 }
1217
1218 return ERR_PTR(err);
1219 }
1220
1221 int fib_dump_info(struct sk_buff *skb, u32 portid, u32 seq, int event,
1222 u32 tb_id, u8 type, __be32 dst, int dst_len, u8 tos,
1223 struct fib_info *fi, unsigned int flags)
1224 {
1225 struct nlmsghdr *nlh;
1226 struct rtmsg *rtm;
1227
1228 nlh = nlmsg_put(skb, portid, seq, event, sizeof(*rtm), flags);
1229 if (!nlh)
1230 return -EMSGSIZE;
1231
1232 rtm = nlmsg_data(nlh);
1233 rtm->rtm_family = AF_INET;
1234 rtm->rtm_dst_len = dst_len;
1235 rtm->rtm_src_len = 0;
1236 rtm->rtm_tos = tos;
1237 if (tb_id < 256)
1238 rtm->rtm_table = tb_id;
1239 else
1240 rtm->rtm_table = RT_TABLE_COMPAT;
1241 if (nla_put_u32(skb, RTA_TABLE, tb_id))
1242 goto nla_put_failure;
1243 rtm->rtm_type = type;
1244 rtm->rtm_flags = fi->fib_flags;
1245 rtm->rtm_scope = fi->fib_scope;
1246 rtm->rtm_protocol = fi->fib_protocol;
1247
1248 if (rtm->rtm_dst_len &&
1249 nla_put_in_addr(skb, RTA_DST, dst))
1250 goto nla_put_failure;
1251 if (fi->fib_priority &&
1252 nla_put_u32(skb, RTA_PRIORITY, fi->fib_priority))
1253 goto nla_put_failure;
1254 if (rtnetlink_put_metrics(skb, fi->fib_metrics) < 0)
1255 goto nla_put_failure;
1256
1257 if (fi->fib_prefsrc &&
1258 nla_put_in_addr(skb, RTA_PREFSRC, fi->fib_prefsrc))
1259 goto nla_put_failure;
1260 if (fi->fib_nhs == 1) {
1261 struct in_device *in_dev;
1262
1263 if (fi->fib_nh->nh_gw &&
1264 nla_put_in_addr(skb, RTA_GATEWAY, fi->fib_nh->nh_gw))
1265 goto nla_put_failure;
1266 if (fi->fib_nh->nh_oif &&
1267 nla_put_u32(skb, RTA_OIF, fi->fib_nh->nh_oif))
1268 goto nla_put_failure;
1269 if (fi->fib_nh->nh_flags & RTNH_F_LINKDOWN) {
1270 in_dev = __in_dev_get_rtnl(fi->fib_nh->nh_dev);
1271 if (in_dev &&
1272 IN_DEV_IGNORE_ROUTES_WITH_LINKDOWN(in_dev))
1273 rtm->rtm_flags |= RTNH_F_DEAD;
1274 }
1275 #ifdef CONFIG_IP_ROUTE_CLASSID
1276 if (fi->fib_nh[0].nh_tclassid &&
1277 nla_put_u32(skb, RTA_FLOW, fi->fib_nh[0].nh_tclassid))
1278 goto nla_put_failure;
1279 #endif
1280 if (fi->fib_nh->nh_lwtstate)
1281 lwtunnel_fill_encap(skb, fi->fib_nh->nh_lwtstate);
1282 }
1283 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1284 if (fi->fib_nhs > 1) {
1285 struct rtnexthop *rtnh;
1286 struct nlattr *mp;
1287
1288 mp = nla_nest_start(skb, RTA_MULTIPATH);
1289 if (!mp)
1290 goto nla_put_failure;
1291
1292 for_nexthops(fi) {
1293 struct in_device *in_dev;
1294
1295 rtnh = nla_reserve_nohdr(skb, sizeof(*rtnh));
1296 if (!rtnh)
1297 goto nla_put_failure;
1298
1299 rtnh->rtnh_flags = nh->nh_flags & 0xFF;
1300 if (nh->nh_flags & RTNH_F_LINKDOWN) {
1301 in_dev = __in_dev_get_rtnl(nh->nh_dev);
1302 if (in_dev &&
1303 IN_DEV_IGNORE_ROUTES_WITH_LINKDOWN(in_dev))
1304 rtnh->rtnh_flags |= RTNH_F_DEAD;
1305 }
1306 rtnh->rtnh_hops = nh->nh_weight - 1;
1307 rtnh->rtnh_ifindex = nh->nh_oif;
1308
1309 if (nh->nh_gw &&
1310 nla_put_in_addr(skb, RTA_GATEWAY, nh->nh_gw))
1311 goto nla_put_failure;
1312 #ifdef CONFIG_IP_ROUTE_CLASSID
1313 if (nh->nh_tclassid &&
1314 nla_put_u32(skb, RTA_FLOW, nh->nh_tclassid))
1315 goto nla_put_failure;
1316 #endif
1317 if (nh->nh_lwtstate)
1318 lwtunnel_fill_encap(skb, nh->nh_lwtstate);
1319 /* length of rtnetlink header + attributes */
1320 rtnh->rtnh_len = nlmsg_get_pos(skb) - (void *) rtnh;
1321 } endfor_nexthops(fi);
1322
1323 nla_nest_end(skb, mp);
1324 }
1325 #endif
1326 nlmsg_end(skb, nlh);
1327 return 0;
1328
1329 nla_put_failure:
1330 nlmsg_cancel(skb, nlh);
1331 return -EMSGSIZE;
1332 }
1333
1334 /*
1335 * Update FIB if:
1336 * - local address disappeared -> we must delete all the entries
1337 * referring to it.
1338 * - device went down -> we must shutdown all nexthops going via it.
1339 */
1340 int fib_sync_down_addr(struct net *net, __be32 local)
1341 {
1342 int ret = 0;
1343 unsigned int hash = fib_laddr_hashfn(local);
1344 struct hlist_head *head = &fib_info_laddrhash[hash];
1345 struct fib_info *fi;
1346
1347 if (!fib_info_laddrhash || local == 0)
1348 return 0;
1349
1350 hlist_for_each_entry(fi, head, fib_lhash) {
1351 if (!net_eq(fi->fib_net, net))
1352 continue;
1353 if (fi->fib_prefsrc == local) {
1354 fi->fib_flags |= RTNH_F_DEAD;
1355 ret++;
1356 }
1357 }
1358 return ret;
1359 }
1360
1361 /* Event force Flags Description
1362 * NETDEV_CHANGE 0 LINKDOWN Carrier OFF, not for scope host
1363 * NETDEV_DOWN 0 LINKDOWN|DEAD Link down, not for scope host
1364 * NETDEV_DOWN 1 LINKDOWN|DEAD Last address removed
1365 * NETDEV_UNREGISTER 1 LINKDOWN|DEAD Device removed
1366 */
1367 int fib_sync_down_dev(struct net_device *dev, unsigned long event, bool force)
1368 {
1369 int ret = 0;
1370 int scope = RT_SCOPE_NOWHERE;
1371 struct fib_info *prev_fi = NULL;
1372 unsigned int hash = fib_devindex_hashfn(dev->ifindex);
1373 struct hlist_head *head = &fib_info_devhash[hash];
1374 struct fib_nh *nh;
1375
1376 if (force)
1377 scope = -1;
1378
1379 hlist_for_each_entry(nh, head, nh_hash) {
1380 struct fib_info *fi = nh->nh_parent;
1381 int dead;
1382
1383 BUG_ON(!fi->fib_nhs);
1384 if (nh->nh_dev != dev || fi == prev_fi)
1385 continue;
1386 prev_fi = fi;
1387 dead = 0;
1388 change_nexthops(fi) {
1389 if (nexthop_nh->nh_flags & RTNH_F_DEAD)
1390 dead++;
1391 else if (nexthop_nh->nh_dev == dev &&
1392 nexthop_nh->nh_scope != scope) {
1393 switch (event) {
1394 case NETDEV_DOWN:
1395 case NETDEV_UNREGISTER:
1396 nexthop_nh->nh_flags |= RTNH_F_DEAD;
1397 /* fall through */
1398 case NETDEV_CHANGE:
1399 nexthop_nh->nh_flags |= RTNH_F_LINKDOWN;
1400 break;
1401 }
1402 dead++;
1403 }
1404 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1405 if (event == NETDEV_UNREGISTER &&
1406 nexthop_nh->nh_dev == dev) {
1407 dead = fi->fib_nhs;
1408 break;
1409 }
1410 #endif
1411 } endfor_nexthops(fi)
1412 if (dead == fi->fib_nhs) {
1413 switch (event) {
1414 case NETDEV_DOWN:
1415 case NETDEV_UNREGISTER:
1416 fi->fib_flags |= RTNH_F_DEAD;
1417 /* fall through */
1418 case NETDEV_CHANGE:
1419 fi->fib_flags |= RTNH_F_LINKDOWN;
1420 break;
1421 }
1422 ret++;
1423 }
1424
1425 fib_rebalance(fi);
1426 }
1427
1428 return ret;
1429 }
1430
1431 /* Must be invoked inside of an RCU protected region. */
1432 void fib_select_default(const struct flowi4 *flp, struct fib_result *res)
1433 {
1434 struct fib_info *fi = NULL, *last_resort = NULL;
1435 struct hlist_head *fa_head = res->fa_head;
1436 struct fib_table *tb = res->table;
1437 u8 slen = 32 - res->prefixlen;
1438 int order = -1, last_idx = -1;
1439 struct fib_alias *fa, *fa1 = NULL;
1440 u32 last_prio = res->fi->fib_priority;
1441 u8 last_tos = 0;
1442
1443 hlist_for_each_entry_rcu(fa, fa_head, fa_list) {
1444 struct fib_info *next_fi = fa->fa_info;
1445
1446 if (fa->fa_slen != slen)
1447 continue;
1448 if (fa->fa_tos && fa->fa_tos != flp->flowi4_tos)
1449 continue;
1450 if (fa->tb_id != tb->tb_id)
1451 continue;
1452 if (next_fi->fib_priority > last_prio &&
1453 fa->fa_tos == last_tos) {
1454 if (last_tos)
1455 continue;
1456 break;
1457 }
1458 if (next_fi->fib_flags & RTNH_F_DEAD)
1459 continue;
1460 last_tos = fa->fa_tos;
1461 last_prio = next_fi->fib_priority;
1462
1463 if (next_fi->fib_scope != res->scope ||
1464 fa->fa_type != RTN_UNICAST)
1465 continue;
1466 if (!next_fi->fib_nh[0].nh_gw ||
1467 next_fi->fib_nh[0].nh_scope != RT_SCOPE_LINK)
1468 continue;
1469
1470 fib_alias_accessed(fa);
1471
1472 if (!fi) {
1473 if (next_fi != res->fi)
1474 break;
1475 fa1 = fa;
1476 } else if (!fib_detect_death(fi, order, &last_resort,
1477 &last_idx, fa1->fa_default)) {
1478 fib_result_assign(res, fi);
1479 fa1->fa_default = order;
1480 goto out;
1481 }
1482 fi = next_fi;
1483 order++;
1484 }
1485
1486 if (order <= 0 || !fi) {
1487 if (fa1)
1488 fa1->fa_default = -1;
1489 goto out;
1490 }
1491
1492 if (!fib_detect_death(fi, order, &last_resort, &last_idx,
1493 fa1->fa_default)) {
1494 fib_result_assign(res, fi);
1495 fa1->fa_default = order;
1496 goto out;
1497 }
1498
1499 if (last_idx >= 0)
1500 fib_result_assign(res, last_resort);
1501 fa1->fa_default = last_idx;
1502 out:
1503 return;
1504 }
1505
1506 /*
1507 * Dead device goes up. We wake up dead nexthops.
1508 * It takes sense only on multipath routes.
1509 */
1510 int fib_sync_up(struct net_device *dev, unsigned int nh_flags)
1511 {
1512 struct fib_info *prev_fi;
1513 unsigned int hash;
1514 struct hlist_head *head;
1515 struct fib_nh *nh;
1516 int ret;
1517
1518 if (!(dev->flags & IFF_UP))
1519 return 0;
1520
1521 if (nh_flags & RTNH_F_DEAD) {
1522 unsigned int flags = dev_get_flags(dev);
1523
1524 if (flags & (IFF_RUNNING | IFF_LOWER_UP))
1525 nh_flags |= RTNH_F_LINKDOWN;
1526 }
1527
1528 prev_fi = NULL;
1529 hash = fib_devindex_hashfn(dev->ifindex);
1530 head = &fib_info_devhash[hash];
1531 ret = 0;
1532
1533 hlist_for_each_entry(nh, head, nh_hash) {
1534 struct fib_info *fi = nh->nh_parent;
1535 int alive;
1536
1537 BUG_ON(!fi->fib_nhs);
1538 if (nh->nh_dev != dev || fi == prev_fi)
1539 continue;
1540
1541 prev_fi = fi;
1542 alive = 0;
1543 change_nexthops(fi) {
1544 if (!(nexthop_nh->nh_flags & nh_flags)) {
1545 alive++;
1546 continue;
1547 }
1548 if (!nexthop_nh->nh_dev ||
1549 !(nexthop_nh->nh_dev->flags & IFF_UP))
1550 continue;
1551 if (nexthop_nh->nh_dev != dev ||
1552 !__in_dev_get_rtnl(dev))
1553 continue;
1554 alive++;
1555 nexthop_nh->nh_flags &= ~nh_flags;
1556 } endfor_nexthops(fi)
1557
1558 if (alive > 0) {
1559 fi->fib_flags &= ~nh_flags;
1560 ret++;
1561 }
1562
1563 fib_rebalance(fi);
1564 }
1565
1566 return ret;
1567 }
1568
1569 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1570 static bool fib_good_nh(const struct fib_nh *nh)
1571 {
1572 int state = NUD_REACHABLE;
1573
1574 if (nh->nh_scope == RT_SCOPE_LINK) {
1575 struct neighbour *n;
1576
1577 rcu_read_lock_bh();
1578
1579 n = __ipv4_neigh_lookup_noref(nh->nh_dev, nh->nh_gw);
1580 if (n)
1581 state = n->nud_state;
1582
1583 rcu_read_unlock_bh();
1584 }
1585
1586 return !!(state & NUD_VALID);
1587 }
1588
1589 void fib_select_multipath(struct fib_result *res, int hash)
1590 {
1591 struct fib_info *fi = res->fi;
1592 struct net *net = fi->fib_net;
1593 bool first = false;
1594
1595 for_nexthops(fi) {
1596 if (hash > atomic_read(&nh->nh_upper_bound))
1597 continue;
1598
1599 if (!net->ipv4.sysctl_fib_multipath_use_neigh ||
1600 fib_good_nh(nh)) {
1601 res->nh_sel = nhsel;
1602 return;
1603 }
1604 if (!first) {
1605 res->nh_sel = nhsel;
1606 first = true;
1607 }
1608 } endfor_nexthops(fi);
1609 }
1610 #endif
1611
1612 void fib_select_path(struct net *net, struct fib_result *res,
1613 struct flowi4 *fl4, int mp_hash)
1614 {
1615 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1616 if (res->fi->fib_nhs > 1 && fl4->flowi4_oif == 0) {
1617 if (mp_hash < 0)
1618 mp_hash = get_hash_from_flowi4(fl4) >> 1;
1619
1620 fib_select_multipath(res, mp_hash);
1621 }
1622 else
1623 #endif
1624 if (!res->prefixlen &&
1625 res->table->tb_num_default > 1 &&
1626 res->type == RTN_UNICAST && !fl4->flowi4_oif)
1627 fib_select_default(fl4, res);
1628
1629 if (!fl4->saddr)
1630 fl4->saddr = FIB_RES_PREFSRC(net, *res);
1631 }
1632 EXPORT_SYMBOL_GPL(fib_select_path);
Linux kernel - Deliverables
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