ipv4: Adjust semantics of rt->rt_gateway.
[linux-3.10.git] / net / ipv4 / route.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  *              ROUTE - implementation of the IP router.
7  *
8  * Authors:     Ross Biro
9  *              Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
10  *              Alan Cox, <gw4pts@gw4pts.ampr.org>
11  *              Linus Torvalds, <Linus.Torvalds@helsinki.fi>
12  *              Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
13  *
14  * Fixes:
15  *              Alan Cox        :       Verify area fixes.
16  *              Alan Cox        :       cli() protects routing changes
17  *              Rui Oliveira    :       ICMP routing table updates
18  *              (rco@di.uminho.pt)      Routing table insertion and update
19  *              Linus Torvalds  :       Rewrote bits to be sensible
20  *              Alan Cox        :       Added BSD route gw semantics
21  *              Alan Cox        :       Super /proc >4K
22  *              Alan Cox        :       MTU in route table
23  *              Alan Cox        :       MSS actually. Also added the window
24  *                                      clamper.
25  *              Sam Lantinga    :       Fixed route matching in rt_del()
26  *              Alan Cox        :       Routing cache support.
27  *              Alan Cox        :       Removed compatibility cruft.
28  *              Alan Cox        :       RTF_REJECT support.
29  *              Alan Cox        :       TCP irtt support.
30  *              Jonathan Naylor :       Added Metric support.
31  *      Miquel van Smoorenburg  :       BSD API fixes.
32  *      Miquel van Smoorenburg  :       Metrics.
33  *              Alan Cox        :       Use __u32 properly
34  *              Alan Cox        :       Aligned routing errors more closely with BSD
35  *                                      our system is still very different.
36  *              Alan Cox        :       Faster /proc handling
37  *      Alexey Kuznetsov        :       Massive rework to support tree based routing,
38  *                                      routing caches and better behaviour.
39  *
40  *              Olaf Erb        :       irtt wasn't being copied right.
41  *              Bjorn Ekwall    :       Kerneld route support.
42  *              Alan Cox        :       Multicast fixed (I hope)
43  *              Pavel Krauz     :       Limited broadcast fixed
44  *              Mike McLagan    :       Routing by source
45  *      Alexey Kuznetsov        :       End of old history. Split to fib.c and
46  *                                      route.c and rewritten from scratch.
47  *              Andi Kleen      :       Load-limit warning messages.
48  *      Vitaly E. Lavrov        :       Transparent proxy revived after year coma.
49  *      Vitaly E. Lavrov        :       Race condition in ip_route_input_slow.
50  *      Tobias Ringstrom        :       Uninitialized res.type in ip_route_output_slow.
51  *      Vladimir V. Ivanov      :       IP rule info (flowid) is really useful.
52  *              Marc Boucher    :       routing by fwmark
53  *      Robert Olsson           :       Added rt_cache statistics
54  *      Arnaldo C. Melo         :       Convert proc stuff to seq_file
55  *      Eric Dumazet            :       hashed spinlocks and rt_check_expire() fixes.
56  *      Ilia Sotnikov           :       Ignore TOS on PMTUD and Redirect
57  *      Ilia Sotnikov           :       Removed TOS from hash calculations
58  *
59  *              This program is free software; you can redistribute it and/or
60  *              modify it under the terms of the GNU General Public License
61  *              as published by the Free Software Foundation; either version
62  *              2 of the License, or (at your option) any later version.
63  */
64
65 #define pr_fmt(fmt) "IPv4: " fmt
66
67 #include <linux/module.h>
68 #include <asm/uaccess.h>
69 #include <linux/bitops.h>
70 #include <linux/types.h>
71 #include <linux/kernel.h>
72 #include <linux/mm.h>
73 #include <linux/bootmem.h>
74 #include <linux/string.h>
75 #include <linux/socket.h>
76 #include <linux/sockios.h>
77 #include <linux/errno.h>
78 #include <linux/in.h>
79 #include <linux/inet.h>
80 #include <linux/netdevice.h>
81 #include <linux/proc_fs.h>
82 #include <linux/init.h>
83 #include <linux/workqueue.h>
84 #include <linux/skbuff.h>
85 #include <linux/inetdevice.h>
86 #include <linux/igmp.h>
87 #include <linux/pkt_sched.h>
88 #include <linux/mroute.h>
89 #include <linux/netfilter_ipv4.h>
90 #include <linux/random.h>
91 #include <linux/jhash.h>
92 #include <linux/rcupdate.h>
93 #include <linux/times.h>
94 #include <linux/slab.h>
95 #include <linux/prefetch.h>
96 #include <net/dst.h>
97 #include <net/net_namespace.h>
98 #include <net/protocol.h>
99 #include <net/ip.h>
100 #include <net/route.h>
101 #include <net/inetpeer.h>
102 #include <net/sock.h>
103 #include <net/ip_fib.h>
104 #include <net/arp.h>
105 #include <net/tcp.h>
106 #include <net/icmp.h>
107 #include <net/xfrm.h>
108 #include <net/netevent.h>
109 #include <net/rtnetlink.h>
110 #ifdef CONFIG_SYSCTL
111 #include <linux/sysctl.h>
112 #include <linux/kmemleak.h>
113 #endif
114 #include <net/secure_seq.h>
115
116 #define RT_FL_TOS(oldflp4) \
117         ((oldflp4)->flowi4_tos & (IPTOS_RT_MASK | RTO_ONLINK))
118
119 #define IP_MAX_MTU      0xFFF0
120
121 #define RT_GC_TIMEOUT (300*HZ)
122
123 static int ip_rt_max_size;
124 static int ip_rt_gc_timeout __read_mostly       = RT_GC_TIMEOUT;
125 static int ip_rt_gc_interval __read_mostly  = 60 * HZ;
126 static int ip_rt_gc_min_interval __read_mostly  = HZ / 2;
127 static int ip_rt_redirect_number __read_mostly  = 9;
128 static int ip_rt_redirect_load __read_mostly    = HZ / 50;
129 static int ip_rt_redirect_silence __read_mostly = ((HZ / 50) << (9 + 1));
130 static int ip_rt_error_cost __read_mostly       = HZ;
131 static int ip_rt_error_burst __read_mostly      = 5 * HZ;
132 static int ip_rt_gc_elasticity __read_mostly    = 8;
133 static int ip_rt_mtu_expires __read_mostly      = 10 * 60 * HZ;
134 static int ip_rt_min_pmtu __read_mostly         = 512 + 20 + 20;
135 static int ip_rt_min_advmss __read_mostly       = 256;
136
137 /*
138  *      Interface to generic destination cache.
139  */
140
141 static struct dst_entry *ipv4_dst_check(struct dst_entry *dst, u32 cookie);
142 static unsigned int      ipv4_default_advmss(const struct dst_entry *dst);
143 static unsigned int      ipv4_mtu(const struct dst_entry *dst);
144 static void              ipv4_dst_destroy(struct dst_entry *dst);
145 static struct dst_entry *ipv4_negative_advice(struct dst_entry *dst);
146 static void              ipv4_link_failure(struct sk_buff *skb);
147 static void              ip_rt_update_pmtu(struct dst_entry *dst, struct sock *sk,
148                                            struct sk_buff *skb, u32 mtu);
149 static void              ip_do_redirect(struct dst_entry *dst, struct sock *sk,
150                                         struct sk_buff *skb);
151
152 static void ipv4_dst_ifdown(struct dst_entry *dst, struct net_device *dev,
153                             int how)
154 {
155 }
156
157 static u32 *ipv4_cow_metrics(struct dst_entry *dst, unsigned long old)
158 {
159         WARN_ON(1);
160         return NULL;
161 }
162
163 static struct neighbour *ipv4_neigh_lookup(const struct dst_entry *dst,
164                                            struct sk_buff *skb,
165                                            const void *daddr);
166
167 static struct dst_ops ipv4_dst_ops = {
168         .family =               AF_INET,
169         .protocol =             cpu_to_be16(ETH_P_IP),
170         .check =                ipv4_dst_check,
171         .default_advmss =       ipv4_default_advmss,
172         .mtu =                  ipv4_mtu,
173         .cow_metrics =          ipv4_cow_metrics,
174         .destroy =              ipv4_dst_destroy,
175         .ifdown =               ipv4_dst_ifdown,
176         .negative_advice =      ipv4_negative_advice,
177         .link_failure =         ipv4_link_failure,
178         .update_pmtu =          ip_rt_update_pmtu,
179         .redirect =             ip_do_redirect,
180         .local_out =            __ip_local_out,
181         .neigh_lookup =         ipv4_neigh_lookup,
182 };
183
184 #define ECN_OR_COST(class)      TC_PRIO_##class
185
186 const __u8 ip_tos2prio[16] = {
187         TC_PRIO_BESTEFFORT,
188         ECN_OR_COST(BESTEFFORT),
189         TC_PRIO_BESTEFFORT,
190         ECN_OR_COST(BESTEFFORT),
191         TC_PRIO_BULK,
192         ECN_OR_COST(BULK),
193         TC_PRIO_BULK,
194         ECN_OR_COST(BULK),
195         TC_PRIO_INTERACTIVE,
196         ECN_OR_COST(INTERACTIVE),
197         TC_PRIO_INTERACTIVE,
198         ECN_OR_COST(INTERACTIVE),
199         TC_PRIO_INTERACTIVE_BULK,
200         ECN_OR_COST(INTERACTIVE_BULK),
201         TC_PRIO_INTERACTIVE_BULK,
202         ECN_OR_COST(INTERACTIVE_BULK)
203 };
204 EXPORT_SYMBOL(ip_tos2prio);
205
206 static DEFINE_PER_CPU(struct rt_cache_stat, rt_cache_stat);
207 #define RT_CACHE_STAT_INC(field) __this_cpu_inc(rt_cache_stat.field)
208
209 static inline int rt_genid(struct net *net)
210 {
211         return atomic_read(&net->ipv4.rt_genid);
212 }
213
214 #ifdef CONFIG_PROC_FS
215 static void *rt_cache_seq_start(struct seq_file *seq, loff_t *pos)
216 {
217         if (*pos)
218                 return NULL;
219         return SEQ_START_TOKEN;
220 }
221
222 static void *rt_cache_seq_next(struct seq_file *seq, void *v, loff_t *pos)
223 {
224         ++*pos;
225         return NULL;
226 }
227
228 static void rt_cache_seq_stop(struct seq_file *seq, void *v)
229 {
230 }
231
232 static int rt_cache_seq_show(struct seq_file *seq, void *v)
233 {
234         if (v == SEQ_START_TOKEN)
235                 seq_printf(seq, "%-127s\n",
236                            "Iface\tDestination\tGateway \tFlags\t\tRefCnt\tUse\t"
237                            "Metric\tSource\t\tMTU\tWindow\tIRTT\tTOS\tHHRef\t"
238                            "HHUptod\tSpecDst");
239         return 0;
240 }
241
242 static const struct seq_operations rt_cache_seq_ops = {
243         .start  = rt_cache_seq_start,
244         .next   = rt_cache_seq_next,
245         .stop   = rt_cache_seq_stop,
246         .show   = rt_cache_seq_show,
247 };
248
249 static int rt_cache_seq_open(struct inode *inode, struct file *file)
250 {
251         return seq_open(file, &rt_cache_seq_ops);
252 }
253
254 static const struct file_operations rt_cache_seq_fops = {
255         .owner   = THIS_MODULE,
256         .open    = rt_cache_seq_open,
257         .read    = seq_read,
258         .llseek  = seq_lseek,
259         .release = seq_release,
260 };
261
262
263 static void *rt_cpu_seq_start(struct seq_file *seq, loff_t *pos)
264 {
265         int cpu;
266
267         if (*pos == 0)
268                 return SEQ_START_TOKEN;
269
270         for (cpu = *pos-1; cpu < nr_cpu_ids; ++cpu) {
271                 if (!cpu_possible(cpu))
272                         continue;
273                 *pos = cpu+1;
274                 return &per_cpu(rt_cache_stat, cpu);
275         }
276         return NULL;
277 }
278
279 static void *rt_cpu_seq_next(struct seq_file *seq, void *v, loff_t *pos)
280 {
281         int cpu;
282
283         for (cpu = *pos; cpu < nr_cpu_ids; ++cpu) {
284                 if (!cpu_possible(cpu))
285                         continue;
286                 *pos = cpu+1;
287                 return &per_cpu(rt_cache_stat, cpu);
288         }
289         return NULL;
290
291 }
292
293 static void rt_cpu_seq_stop(struct seq_file *seq, void *v)
294 {
295
296 }
297
298 static int rt_cpu_seq_show(struct seq_file *seq, void *v)
299 {
300         struct rt_cache_stat *st = v;
301
302         if (v == SEQ_START_TOKEN) {
303                 seq_printf(seq, "entries  in_hit in_slow_tot in_slow_mc in_no_route in_brd in_martian_dst in_martian_src  out_hit out_slow_tot out_slow_mc  gc_total gc_ignored gc_goal_miss gc_dst_overflow in_hlist_search out_hlist_search\n");
304                 return 0;
305         }
306
307         seq_printf(seq,"%08x  %08x %08x %08x %08x %08x %08x %08x "
308                    " %08x %08x %08x %08x %08x %08x %08x %08x %08x \n",
309                    dst_entries_get_slow(&ipv4_dst_ops),
310                    st->in_hit,
311                    st->in_slow_tot,
312                    st->in_slow_mc,
313                    st->in_no_route,
314                    st->in_brd,
315                    st->in_martian_dst,
316                    st->in_martian_src,
317
318                    st->out_hit,
319                    st->out_slow_tot,
320                    st->out_slow_mc,
321
322                    st->gc_total,
323                    st->gc_ignored,
324                    st->gc_goal_miss,
325                    st->gc_dst_overflow,
326                    st->in_hlist_search,
327                    st->out_hlist_search
328                 );
329         return 0;
330 }
331
332 static const struct seq_operations rt_cpu_seq_ops = {
333         .start  = rt_cpu_seq_start,
334         .next   = rt_cpu_seq_next,
335         .stop   = rt_cpu_seq_stop,
336         .show   = rt_cpu_seq_show,
337 };
338
339
340 static int rt_cpu_seq_open(struct inode *inode, struct file *file)
341 {
342         return seq_open(file, &rt_cpu_seq_ops);
343 }
344
345 static const struct file_operations rt_cpu_seq_fops = {
346         .owner   = THIS_MODULE,
347         .open    = rt_cpu_seq_open,
348         .read    = seq_read,
349         .llseek  = seq_lseek,
350         .release = seq_release,
351 };
352
353 #ifdef CONFIG_IP_ROUTE_CLASSID
354 static int rt_acct_proc_show(struct seq_file *m, void *v)
355 {
356         struct ip_rt_acct *dst, *src;
357         unsigned int i, j;
358
359         dst = kcalloc(256, sizeof(struct ip_rt_acct), GFP_KERNEL);
360         if (!dst)
361                 return -ENOMEM;
362
363         for_each_possible_cpu(i) {
364                 src = (struct ip_rt_acct *)per_cpu_ptr(ip_rt_acct, i);
365                 for (j = 0; j < 256; j++) {
366                         dst[j].o_bytes   += src[j].o_bytes;
367                         dst[j].o_packets += src[j].o_packets;
368                         dst[j].i_bytes   += src[j].i_bytes;
369                         dst[j].i_packets += src[j].i_packets;
370                 }
371         }
372
373         seq_write(m, dst, 256 * sizeof(struct ip_rt_acct));
374         kfree(dst);
375         return 0;
376 }
377
378 static int rt_acct_proc_open(struct inode *inode, struct file *file)
379 {
380         return single_open(file, rt_acct_proc_show, NULL);
381 }
382
383 static const struct file_operations rt_acct_proc_fops = {
384         .owner          = THIS_MODULE,
385         .open           = rt_acct_proc_open,
386         .read           = seq_read,
387         .llseek         = seq_lseek,
388         .release        = single_release,
389 };
390 #endif
391
392 static int __net_init ip_rt_do_proc_init(struct net *net)
393 {
394         struct proc_dir_entry *pde;
395
396         pde = proc_net_fops_create(net, "rt_cache", S_IRUGO,
397                         &rt_cache_seq_fops);
398         if (!pde)
399                 goto err1;
400
401         pde = proc_create("rt_cache", S_IRUGO,
402                           net->proc_net_stat, &rt_cpu_seq_fops);
403         if (!pde)
404                 goto err2;
405
406 #ifdef CONFIG_IP_ROUTE_CLASSID
407         pde = proc_create("rt_acct", 0, net->proc_net, &rt_acct_proc_fops);
408         if (!pde)
409                 goto err3;
410 #endif
411         return 0;
412
413 #ifdef CONFIG_IP_ROUTE_CLASSID
414 err3:
415         remove_proc_entry("rt_cache", net->proc_net_stat);
416 #endif
417 err2:
418         remove_proc_entry("rt_cache", net->proc_net);
419 err1:
420         return -ENOMEM;
421 }
422
423 static void __net_exit ip_rt_do_proc_exit(struct net *net)
424 {
425         remove_proc_entry("rt_cache", net->proc_net_stat);
426         remove_proc_entry("rt_cache", net->proc_net);
427 #ifdef CONFIG_IP_ROUTE_CLASSID
428         remove_proc_entry("rt_acct", net->proc_net);
429 #endif
430 }
431
432 static struct pernet_operations ip_rt_proc_ops __net_initdata =  {
433         .init = ip_rt_do_proc_init,
434         .exit = ip_rt_do_proc_exit,
435 };
436
437 static int __init ip_rt_proc_init(void)
438 {
439         return register_pernet_subsys(&ip_rt_proc_ops);
440 }
441
442 #else
443 static inline int ip_rt_proc_init(void)
444 {
445         return 0;
446 }
447 #endif /* CONFIG_PROC_FS */
448
449 static inline int rt_is_expired(struct rtable *rth)
450 {
451         return rth->rt_genid != rt_genid(dev_net(rth->dst.dev));
452 }
453
454 /*
455  * Perturbation of rt_genid by a small quantity [1..256]
456  * Using 8 bits of shuffling ensure we can call rt_cache_invalidate()
457  * many times (2^24) without giving recent rt_genid.
458  * Jenkins hash is strong enough that litle changes of rt_genid are OK.
459  */
460 static void rt_cache_invalidate(struct net *net)
461 {
462         unsigned char shuffle;
463
464         get_random_bytes(&shuffle, sizeof(shuffle));
465         atomic_add(shuffle + 1U, &net->ipv4.rt_genid);
466 }
467
468 /*
469  * delay < 0  : invalidate cache (fast : entries will be deleted later)
470  * delay >= 0 : invalidate & flush cache (can be long)
471  */
472 void rt_cache_flush(struct net *net, int delay)
473 {
474         rt_cache_invalidate(net);
475 }
476
477 static struct neighbour *ipv4_neigh_lookup(const struct dst_entry *dst,
478                                            struct sk_buff *skb,
479                                            const void *daddr)
480 {
481         struct net_device *dev = dst->dev;
482         const __be32 *pkey = daddr;
483         const struct rtable *rt;
484         struct neighbour *n;
485
486         rt = (const struct rtable *) dst;
487         if (rt->rt_gateway)
488                 pkey = (const __be32 *) &rt->rt_gateway;
489         else if (skb)
490                 pkey = &ip_hdr(skb)->daddr;
491
492         n = __ipv4_neigh_lookup(dev, *(__force u32 *)pkey);
493         if (n)
494                 return n;
495         return neigh_create(&arp_tbl, pkey, dev);
496 }
497
498 /*
499  * Peer allocation may fail only in serious out-of-memory conditions.  However
500  * we still can generate some output.
501  * Random ID selection looks a bit dangerous because we have no chances to
502  * select ID being unique in a reasonable period of time.
503  * But broken packet identifier may be better than no packet at all.
504  */
505 static void ip_select_fb_ident(struct iphdr *iph)
506 {
507         static DEFINE_SPINLOCK(ip_fb_id_lock);
508         static u32 ip_fallback_id;
509         u32 salt;
510
511         spin_lock_bh(&ip_fb_id_lock);
512         salt = secure_ip_id((__force __be32)ip_fallback_id ^ iph->daddr);
513         iph->id = htons(salt & 0xFFFF);
514         ip_fallback_id = salt;
515         spin_unlock_bh(&ip_fb_id_lock);
516 }
517
518 void __ip_select_ident(struct iphdr *iph, struct dst_entry *dst, int more)
519 {
520         struct net *net = dev_net(dst->dev);
521         struct inet_peer *peer;
522
523         peer = inet_getpeer_v4(net->ipv4.peers, iph->daddr, 1);
524         if (peer) {
525                 iph->id = htons(inet_getid(peer, more));
526                 inet_putpeer(peer);
527                 return;
528         }
529
530         ip_select_fb_ident(iph);
531 }
532 EXPORT_SYMBOL(__ip_select_ident);
533
534 static void __build_flow_key(struct flowi4 *fl4, const struct sock *sk,
535                              const struct iphdr *iph,
536                              int oif, u8 tos,
537                              u8 prot, u32 mark, int flow_flags)
538 {
539         if (sk) {
540                 const struct inet_sock *inet = inet_sk(sk);
541
542                 oif = sk->sk_bound_dev_if;
543                 mark = sk->sk_mark;
544                 tos = RT_CONN_FLAGS(sk);
545                 prot = inet->hdrincl ? IPPROTO_RAW : sk->sk_protocol;
546         }
547         flowi4_init_output(fl4, oif, mark, tos,
548                            RT_SCOPE_UNIVERSE, prot,
549                            flow_flags,
550                            iph->daddr, iph->saddr, 0, 0);
551 }
552
553 static void build_skb_flow_key(struct flowi4 *fl4, const struct sk_buff *skb,
554                                const struct sock *sk)
555 {
556         const struct iphdr *iph = ip_hdr(skb);
557         int oif = skb->dev->ifindex;
558         u8 tos = RT_TOS(iph->tos);
559         u8 prot = iph->protocol;
560         u32 mark = skb->mark;
561
562         __build_flow_key(fl4, sk, iph, oif, tos, prot, mark, 0);
563 }
564
565 static void build_sk_flow_key(struct flowi4 *fl4, const struct sock *sk)
566 {
567         const struct inet_sock *inet = inet_sk(sk);
568         const struct ip_options_rcu *inet_opt;
569         __be32 daddr = inet->inet_daddr;
570
571         rcu_read_lock();
572         inet_opt = rcu_dereference(inet->inet_opt);
573         if (inet_opt && inet_opt->opt.srr)
574                 daddr = inet_opt->opt.faddr;
575         flowi4_init_output(fl4, sk->sk_bound_dev_if, sk->sk_mark,
576                            RT_CONN_FLAGS(sk), RT_SCOPE_UNIVERSE,
577                            inet->hdrincl ? IPPROTO_RAW : sk->sk_protocol,
578                            inet_sk_flowi_flags(sk),
579                            daddr, inet->inet_saddr, 0, 0);
580         rcu_read_unlock();
581 }
582
583 static void ip_rt_build_flow_key(struct flowi4 *fl4, const struct sock *sk,
584                                  const struct sk_buff *skb)
585 {
586         if (skb)
587                 build_skb_flow_key(fl4, skb, sk);
588         else
589                 build_sk_flow_key(fl4, sk);
590 }
591
592 static DEFINE_SEQLOCK(fnhe_seqlock);
593
594 static struct fib_nh_exception *fnhe_oldest(struct fnhe_hash_bucket *hash)
595 {
596         struct fib_nh_exception *fnhe, *oldest;
597
598         oldest = rcu_dereference(hash->chain);
599         for (fnhe = rcu_dereference(oldest->fnhe_next); fnhe;
600              fnhe = rcu_dereference(fnhe->fnhe_next)) {
601                 if (time_before(fnhe->fnhe_stamp, oldest->fnhe_stamp))
602                         oldest = fnhe;
603         }
604         return oldest;
605 }
606
607 static inline u32 fnhe_hashfun(__be32 daddr)
608 {
609         u32 hval;
610
611         hval = (__force u32) daddr;
612         hval ^= (hval >> 11) ^ (hval >> 22);
613
614         return hval & (FNHE_HASH_SIZE - 1);
615 }
616
617 static void update_or_create_fnhe(struct fib_nh *nh, __be32 daddr, __be32 gw,
618                                   u32 pmtu, unsigned long expires)
619 {
620         struct fnhe_hash_bucket *hash;
621         struct fib_nh_exception *fnhe;
622         int depth;
623         u32 hval = fnhe_hashfun(daddr);
624
625         write_seqlock_bh(&fnhe_seqlock);
626
627         hash = nh->nh_exceptions;
628         if (!hash) {
629                 hash = kzalloc(FNHE_HASH_SIZE * sizeof(*hash), GFP_ATOMIC);
630                 if (!hash)
631                         goto out_unlock;
632                 nh->nh_exceptions = hash;
633         }
634
635         hash += hval;
636
637         depth = 0;
638         for (fnhe = rcu_dereference(hash->chain); fnhe;
639              fnhe = rcu_dereference(fnhe->fnhe_next)) {
640                 if (fnhe->fnhe_daddr == daddr)
641                         break;
642                 depth++;
643         }
644
645         if (fnhe) {
646                 if (gw)
647                         fnhe->fnhe_gw = gw;
648                 if (pmtu) {
649                         fnhe->fnhe_pmtu = pmtu;
650                         fnhe->fnhe_expires = expires;
651                 }
652         } else {
653                 if (depth > FNHE_RECLAIM_DEPTH)
654                         fnhe = fnhe_oldest(hash);
655                 else {
656                         fnhe = kzalloc(sizeof(*fnhe), GFP_ATOMIC);
657                         if (!fnhe)
658                                 goto out_unlock;
659
660                         fnhe->fnhe_next = hash->chain;
661                         rcu_assign_pointer(hash->chain, fnhe);
662                 }
663                 fnhe->fnhe_daddr = daddr;
664                 fnhe->fnhe_gw = gw;
665                 fnhe->fnhe_pmtu = pmtu;
666                 fnhe->fnhe_expires = expires;
667         }
668
669         fnhe->fnhe_stamp = jiffies;
670
671 out_unlock:
672         write_sequnlock_bh(&fnhe_seqlock);
673         return;
674 }
675
676 static void __ip_do_redirect(struct rtable *rt, struct sk_buff *skb, struct flowi4 *fl4)
677 {
678         __be32 new_gw = icmp_hdr(skb)->un.gateway;
679         __be32 old_gw = ip_hdr(skb)->saddr;
680         struct net_device *dev = skb->dev;
681         struct in_device *in_dev;
682         struct fib_result res;
683         struct neighbour *n;
684         struct net *net;
685
686         switch (icmp_hdr(skb)->code & 7) {
687         case ICMP_REDIR_NET:
688         case ICMP_REDIR_NETTOS:
689         case ICMP_REDIR_HOST:
690         case ICMP_REDIR_HOSTTOS:
691                 break;
692
693         default:
694                 return;
695         }
696
697         if (rt->rt_gateway != old_gw)
698                 return;
699
700         in_dev = __in_dev_get_rcu(dev);
701         if (!in_dev)
702                 return;
703
704         net = dev_net(dev);
705         if (new_gw == old_gw || !IN_DEV_RX_REDIRECTS(in_dev) ||
706             ipv4_is_multicast(new_gw) || ipv4_is_lbcast(new_gw) ||
707             ipv4_is_zeronet(new_gw))
708                 goto reject_redirect;
709
710         if (!IN_DEV_SHARED_MEDIA(in_dev)) {
711                 if (!inet_addr_onlink(in_dev, new_gw, old_gw))
712                         goto reject_redirect;
713                 if (IN_DEV_SEC_REDIRECTS(in_dev) && ip_fib_check_default(new_gw, dev))
714                         goto reject_redirect;
715         } else {
716                 if (inet_addr_type(net, new_gw) != RTN_UNICAST)
717                         goto reject_redirect;
718         }
719
720         n = ipv4_neigh_lookup(&rt->dst, NULL, &new_gw);
721         if (n) {
722                 if (!(n->nud_state & NUD_VALID)) {
723                         neigh_event_send(n, NULL);
724                 } else {
725                         if (fib_lookup(net, fl4, &res) == 0) {
726                                 struct fib_nh *nh = &FIB_RES_NH(res);
727
728                                 update_or_create_fnhe(nh, fl4->daddr, new_gw,
729                                                       0, 0);
730                         }
731                         rt->rt_gateway = new_gw;
732                         rt->rt_flags |= RTCF_REDIRECTED;
733                         call_netevent_notifiers(NETEVENT_NEIGH_UPDATE, n);
734                 }
735                 neigh_release(n);
736         }
737         return;
738
739 reject_redirect:
740 #ifdef CONFIG_IP_ROUTE_VERBOSE
741         if (IN_DEV_LOG_MARTIANS(in_dev)) {
742                 const struct iphdr *iph = (const struct iphdr *) skb->data;
743                 __be32 daddr = iph->daddr;
744                 __be32 saddr = iph->saddr;
745
746                 net_info_ratelimited("Redirect from %pI4 on %s about %pI4 ignored\n"
747                                      "  Advised path = %pI4 -> %pI4\n",
748                                      &old_gw, dev->name, &new_gw,
749                                      &saddr, &daddr);
750         }
751 #endif
752         ;
753 }
754
755 static void ip_do_redirect(struct dst_entry *dst, struct sock *sk, struct sk_buff *skb)
756 {
757         struct rtable *rt;
758         struct flowi4 fl4;
759
760         rt = (struct rtable *) dst;
761
762         ip_rt_build_flow_key(&fl4, sk, skb);
763         __ip_do_redirect(rt, skb, &fl4);
764 }
765
766 static struct dst_entry *ipv4_negative_advice(struct dst_entry *dst)
767 {
768         struct rtable *rt = (struct rtable *)dst;
769         struct dst_entry *ret = dst;
770
771         if (rt) {
772                 if (dst->obsolete > 0) {
773                         ip_rt_put(rt);
774                         ret = NULL;
775                 } else if ((rt->rt_flags & RTCF_REDIRECTED) ||
776                            rt->dst.expires) {
777                         ip_rt_put(rt);
778                         ret = NULL;
779                 }
780         }
781         return ret;
782 }
783
784 /*
785  * Algorithm:
786  *      1. The first ip_rt_redirect_number redirects are sent
787  *         with exponential backoff, then we stop sending them at all,
788  *         assuming that the host ignores our redirects.
789  *      2. If we did not see packets requiring redirects
790  *         during ip_rt_redirect_silence, we assume that the host
791  *         forgot redirected route and start to send redirects again.
792  *
793  * This algorithm is much cheaper and more intelligent than dumb load limiting
794  * in icmp.c.
795  *
796  * NOTE. Do not forget to inhibit load limiting for redirects (redundant)
797  * and "frag. need" (breaks PMTU discovery) in icmp.c.
798  */
799
800 void ip_rt_send_redirect(struct sk_buff *skb)
801 {
802         struct rtable *rt = skb_rtable(skb);
803         struct in_device *in_dev;
804         struct inet_peer *peer;
805         struct net *net;
806         int log_martians;
807
808         rcu_read_lock();
809         in_dev = __in_dev_get_rcu(rt->dst.dev);
810         if (!in_dev || !IN_DEV_TX_REDIRECTS(in_dev)) {
811                 rcu_read_unlock();
812                 return;
813         }
814         log_martians = IN_DEV_LOG_MARTIANS(in_dev);
815         rcu_read_unlock();
816
817         net = dev_net(rt->dst.dev);
818         peer = inet_getpeer_v4(net->ipv4.peers, ip_hdr(skb)->saddr, 1);
819         if (!peer) {
820                 icmp_send(skb, ICMP_REDIRECT, ICMP_REDIR_HOST, rt->rt_gateway);
821                 return;
822         }
823
824         /* No redirected packets during ip_rt_redirect_silence;
825          * reset the algorithm.
826          */
827         if (time_after(jiffies, peer->rate_last + ip_rt_redirect_silence))
828                 peer->rate_tokens = 0;
829
830         /* Too many ignored redirects; do not send anything
831          * set dst.rate_last to the last seen redirected packet.
832          */
833         if (peer->rate_tokens >= ip_rt_redirect_number) {
834                 peer->rate_last = jiffies;
835                 goto out_put_peer;
836         }
837
838         /* Check for load limit; set rate_last to the latest sent
839          * redirect.
840          */
841         if (peer->rate_tokens == 0 ||
842             time_after(jiffies,
843                        (peer->rate_last +
844                         (ip_rt_redirect_load << peer->rate_tokens)))) {
845                 icmp_send(skb, ICMP_REDIRECT, ICMP_REDIR_HOST, rt->rt_gateway);
846                 peer->rate_last = jiffies;
847                 ++peer->rate_tokens;
848 #ifdef CONFIG_IP_ROUTE_VERBOSE
849                 if (log_martians &&
850                     peer->rate_tokens == ip_rt_redirect_number)
851                         net_warn_ratelimited("host %pI4/if%d ignores redirects for %pI4 to %pI4\n",
852                                              &ip_hdr(skb)->saddr, rt->rt_iif,
853                                              &ip_hdr(skb)->daddr, &rt->rt_gateway);
854 #endif
855         }
856 out_put_peer:
857         inet_putpeer(peer);
858 }
859
860 static int ip_error(struct sk_buff *skb)
861 {
862         struct in_device *in_dev = __in_dev_get_rcu(skb->dev);
863         struct rtable *rt = skb_rtable(skb);
864         struct inet_peer *peer;
865         unsigned long now;
866         struct net *net;
867         bool send;
868         int code;
869
870         net = dev_net(rt->dst.dev);
871         if (!IN_DEV_FORWARD(in_dev)) {
872                 switch (rt->dst.error) {
873                 case EHOSTUNREACH:
874                         IP_INC_STATS_BH(net, IPSTATS_MIB_INADDRERRORS);
875                         break;
876
877                 case ENETUNREACH:
878                         IP_INC_STATS_BH(net, IPSTATS_MIB_INNOROUTES);
879                         break;
880                 }
881                 goto out;
882         }
883
884         switch (rt->dst.error) {
885         case EINVAL:
886         default:
887                 goto out;
888         case EHOSTUNREACH:
889                 code = ICMP_HOST_UNREACH;
890                 break;
891         case ENETUNREACH:
892                 code = ICMP_NET_UNREACH;
893                 IP_INC_STATS_BH(net, IPSTATS_MIB_INNOROUTES);
894                 break;
895         case EACCES:
896                 code = ICMP_PKT_FILTERED;
897                 break;
898         }
899
900         peer = inet_getpeer_v4(net->ipv4.peers, ip_hdr(skb)->saddr, 1);
901
902         send = true;
903         if (peer) {
904                 now = jiffies;
905                 peer->rate_tokens += now - peer->rate_last;
906                 if (peer->rate_tokens > ip_rt_error_burst)
907                         peer->rate_tokens = ip_rt_error_burst;
908                 peer->rate_last = now;
909                 if (peer->rate_tokens >= ip_rt_error_cost)
910                         peer->rate_tokens -= ip_rt_error_cost;
911                 else
912                         send = false;
913                 inet_putpeer(peer);
914         }
915         if (send)
916                 icmp_send(skb, ICMP_DEST_UNREACH, code, 0);
917
918 out:    kfree_skb(skb);
919         return 0;
920 }
921
922 static void __ip_rt_update_pmtu(struct rtable *rt, struct flowi4 *fl4, u32 mtu)
923 {
924         struct fib_result res;
925
926         if (mtu < ip_rt_min_pmtu)
927                 mtu = ip_rt_min_pmtu;
928
929         if (fib_lookup(dev_net(rt->dst.dev), fl4, &res) == 0) {
930                 struct fib_nh *nh = &FIB_RES_NH(res);
931
932                 update_or_create_fnhe(nh, fl4->daddr, 0, mtu,
933                                       jiffies + ip_rt_mtu_expires);
934         }
935         rt->rt_pmtu = mtu;
936         dst_set_expires(&rt->dst, ip_rt_mtu_expires);
937 }
938
939 static void ip_rt_update_pmtu(struct dst_entry *dst, struct sock *sk,
940                               struct sk_buff *skb, u32 mtu)
941 {
942         struct rtable *rt = (struct rtable *) dst;
943         struct flowi4 fl4;
944
945         ip_rt_build_flow_key(&fl4, sk, skb);
946         __ip_rt_update_pmtu(rt, &fl4, mtu);
947 }
948
949 void ipv4_update_pmtu(struct sk_buff *skb, struct net *net, u32 mtu,
950                       int oif, u32 mark, u8 protocol, int flow_flags)
951 {
952         const struct iphdr *iph = (const struct iphdr *) skb->data;
953         struct flowi4 fl4;
954         struct rtable *rt;
955
956         __build_flow_key(&fl4, NULL, iph, oif,
957                          RT_TOS(iph->tos), protocol, mark, flow_flags);
958         rt = __ip_route_output_key(net, &fl4);
959         if (!IS_ERR(rt)) {
960                 __ip_rt_update_pmtu(rt, &fl4, mtu);
961                 ip_rt_put(rt);
962         }
963 }
964 EXPORT_SYMBOL_GPL(ipv4_update_pmtu);
965
966 void ipv4_sk_update_pmtu(struct sk_buff *skb, struct sock *sk, u32 mtu)
967 {
968         const struct iphdr *iph = (const struct iphdr *) skb->data;
969         struct flowi4 fl4;
970         struct rtable *rt;
971
972         __build_flow_key(&fl4, sk, iph, 0, 0, 0, 0, 0);
973         rt = __ip_route_output_key(sock_net(sk), &fl4);
974         if (!IS_ERR(rt)) {
975                 __ip_rt_update_pmtu(rt, &fl4, mtu);
976                 ip_rt_put(rt);
977         }
978 }
979 EXPORT_SYMBOL_GPL(ipv4_sk_update_pmtu);
980
981 void ipv4_redirect(struct sk_buff *skb, struct net *net,
982                    int oif, u32 mark, u8 protocol, int flow_flags)
983 {
984         const struct iphdr *iph = (const struct iphdr *) skb->data;
985         struct flowi4 fl4;
986         struct rtable *rt;
987
988         __build_flow_key(&fl4, NULL, iph, oif,
989                          RT_TOS(iph->tos), protocol, mark, flow_flags);
990         rt = __ip_route_output_key(net, &fl4);
991         if (!IS_ERR(rt)) {
992                 __ip_do_redirect(rt, skb, &fl4);
993                 ip_rt_put(rt);
994         }
995 }
996 EXPORT_SYMBOL_GPL(ipv4_redirect);
997
998 void ipv4_sk_redirect(struct sk_buff *skb, struct sock *sk)
999 {
1000         const struct iphdr *iph = (const struct iphdr *) skb->data;
1001         struct flowi4 fl4;
1002         struct rtable *rt;
1003
1004         __build_flow_key(&fl4, sk, iph, 0, 0, 0, 0, 0);
1005         rt = __ip_route_output_key(sock_net(sk), &fl4);
1006         if (!IS_ERR(rt)) {
1007                 __ip_do_redirect(rt, skb, &fl4);
1008                 ip_rt_put(rt);
1009         }
1010 }
1011 EXPORT_SYMBOL_GPL(ipv4_sk_redirect);
1012
1013 static struct dst_entry *ipv4_dst_check(struct dst_entry *dst, u32 cookie)
1014 {
1015         struct rtable *rt = (struct rtable *) dst;
1016
1017         if (rt_is_expired(rt))
1018                 return NULL;
1019         return dst;
1020 }
1021
1022 static void ipv4_dst_destroy(struct dst_entry *dst)
1023 {
1024         struct rtable *rt = (struct rtable *) dst;
1025
1026         if (rt->fi) {
1027                 fib_info_put(rt->fi);
1028                 rt->fi = NULL;
1029         }
1030 }
1031
1032
1033 static void ipv4_link_failure(struct sk_buff *skb)
1034 {
1035         struct rtable *rt;
1036
1037         icmp_send(skb, ICMP_DEST_UNREACH, ICMP_HOST_UNREACH, 0);
1038
1039         rt = skb_rtable(skb);
1040         if (rt)
1041                 dst_set_expires(&rt->dst, 0);
1042 }
1043
1044 static int ip_rt_bug(struct sk_buff *skb)
1045 {
1046         pr_debug("%s: %pI4 -> %pI4, %s\n",
1047                  __func__, &ip_hdr(skb)->saddr, &ip_hdr(skb)->daddr,
1048                  skb->dev ? skb->dev->name : "?");
1049         kfree_skb(skb);
1050         WARN_ON(1);
1051         return 0;
1052 }
1053
1054 /*
1055    We do not cache source address of outgoing interface,
1056    because it is used only by IP RR, TS and SRR options,
1057    so that it out of fast path.
1058
1059    BTW remember: "addr" is allowed to be not aligned
1060    in IP options!
1061  */
1062
1063 void ip_rt_get_source(u8 *addr, struct sk_buff *skb, struct rtable *rt)
1064 {
1065         __be32 src;
1066
1067         if (rt_is_output_route(rt))
1068                 src = ip_hdr(skb)->saddr;
1069         else {
1070                 struct fib_result res;
1071                 struct flowi4 fl4;
1072                 struct iphdr *iph;
1073
1074                 iph = ip_hdr(skb);
1075
1076                 memset(&fl4, 0, sizeof(fl4));
1077                 fl4.daddr = iph->daddr;
1078                 fl4.saddr = iph->saddr;
1079                 fl4.flowi4_tos = RT_TOS(iph->tos);
1080                 fl4.flowi4_oif = rt->dst.dev->ifindex;
1081                 fl4.flowi4_iif = skb->dev->ifindex;
1082                 fl4.flowi4_mark = skb->mark;
1083
1084                 rcu_read_lock();
1085                 if (fib_lookup(dev_net(rt->dst.dev), &fl4, &res) == 0)
1086                         src = FIB_RES_PREFSRC(dev_net(rt->dst.dev), res);
1087                 else
1088                         src = inet_select_addr(rt->dst.dev,
1089                                                rt_nexthop(rt, iph->daddr),
1090                                                RT_SCOPE_UNIVERSE);
1091                 rcu_read_unlock();
1092         }
1093         memcpy(addr, &src, 4);
1094 }
1095
1096 #ifdef CONFIG_IP_ROUTE_CLASSID
1097 static void set_class_tag(struct rtable *rt, u32 tag)
1098 {
1099         if (!(rt->dst.tclassid & 0xFFFF))
1100                 rt->dst.tclassid |= tag & 0xFFFF;
1101         if (!(rt->dst.tclassid & 0xFFFF0000))
1102                 rt->dst.tclassid |= tag & 0xFFFF0000;
1103 }
1104 #endif
1105
1106 static unsigned int ipv4_default_advmss(const struct dst_entry *dst)
1107 {
1108         unsigned int advmss = dst_metric_raw(dst, RTAX_ADVMSS);
1109
1110         if (advmss == 0) {
1111                 advmss = max_t(unsigned int, dst->dev->mtu - 40,
1112                                ip_rt_min_advmss);
1113                 if (advmss > 65535 - 40)
1114                         advmss = 65535 - 40;
1115         }
1116         return advmss;
1117 }
1118
1119 static unsigned int ipv4_mtu(const struct dst_entry *dst)
1120 {
1121         const struct rtable *rt = (const struct rtable *) dst;
1122         unsigned int mtu = rt->rt_pmtu;
1123
1124         if (mtu && time_after_eq(jiffies, rt->dst.expires))
1125                 mtu = 0;
1126
1127         if (!mtu)
1128                 mtu = dst_metric_raw(dst, RTAX_MTU);
1129
1130         if (mtu && rt_is_output_route(rt))
1131                 return mtu;
1132
1133         mtu = dst->dev->mtu;
1134
1135         if (unlikely(dst_metric_locked(dst, RTAX_MTU))) {
1136                 if (rt->rt_gateway && mtu > 576)
1137                         mtu = 576;
1138         }
1139
1140         if (mtu > IP_MAX_MTU)
1141                 mtu = IP_MAX_MTU;
1142
1143         return mtu;
1144 }
1145
1146 static void rt_init_metrics(struct rtable *rt, const struct flowi4 *fl4,
1147                             struct fib_info *fi)
1148 {
1149         if (fi->fib_metrics != (u32 *) dst_default_metrics) {
1150                 rt->fi = fi;
1151                 atomic_inc(&fi->fib_clntref);
1152         }
1153         dst_init_metrics(&rt->dst, fi->fib_metrics, true);
1154 }
1155
1156 static void rt_bind_exception(struct rtable *rt, struct fib_nh *nh, __be32 daddr)
1157 {
1158         struct fnhe_hash_bucket *hash = nh->nh_exceptions;
1159         struct fib_nh_exception *fnhe;
1160         u32 hval;
1161
1162         hval = fnhe_hashfun(daddr);
1163
1164 restart:
1165         for (fnhe = rcu_dereference(hash[hval].chain); fnhe;
1166              fnhe = rcu_dereference(fnhe->fnhe_next)) {
1167                 __be32 fnhe_daddr, gw;
1168                 unsigned long expires;
1169                 unsigned int seq;
1170                 u32 pmtu;
1171
1172                 seq = read_seqbegin(&fnhe_seqlock);
1173                 fnhe_daddr = fnhe->fnhe_daddr;
1174                 gw = fnhe->fnhe_gw;
1175                 pmtu = fnhe->fnhe_pmtu;
1176                 expires = fnhe->fnhe_expires;
1177                 if (read_seqretry(&fnhe_seqlock, seq))
1178                         goto restart;
1179                 if (daddr != fnhe_daddr)
1180                         continue;
1181                 if (pmtu) {
1182                         unsigned long diff = expires - jiffies;
1183
1184                         if (time_before(jiffies, expires)) {
1185                                 rt->rt_pmtu = pmtu;
1186                                 dst_set_expires(&rt->dst, diff);
1187                         }
1188                 }
1189                 if (gw)
1190                         rt->rt_gateway = gw;
1191                 fnhe->fnhe_stamp = jiffies;
1192                 break;
1193         }
1194 }
1195
1196 static void rt_set_nexthop(struct rtable *rt, const struct flowi4 *fl4,
1197                            const struct fib_result *res,
1198                            struct fib_info *fi, u16 type, u32 itag)
1199 {
1200         if (fi) {
1201                 struct fib_nh *nh = &FIB_RES_NH(*res);
1202
1203                 if (nh->nh_gw && nh->nh_scope == RT_SCOPE_LINK)
1204                         rt->rt_gateway = nh->nh_gw;
1205                 if (unlikely(nh->nh_exceptions))
1206                         rt_bind_exception(rt, nh, fl4->daddr);
1207                 rt_init_metrics(rt, fl4, fi);
1208 #ifdef CONFIG_IP_ROUTE_CLASSID
1209                 rt->dst.tclassid = FIB_RES_NH(*res).nh_tclassid;
1210 #endif
1211         }
1212
1213 #ifdef CONFIG_IP_ROUTE_CLASSID
1214 #ifdef CONFIG_IP_MULTIPLE_TABLES
1215         set_class_tag(rt, res->tclassid);
1216 #endif
1217         set_class_tag(rt, itag);
1218 #endif
1219 }
1220
1221 static struct rtable *rt_dst_alloc(struct net_device *dev,
1222                                    bool nopolicy, bool noxfrm)
1223 {
1224         return dst_alloc(&ipv4_dst_ops, dev, 1, -1,
1225                          DST_HOST | DST_NOCACHE |
1226                          (nopolicy ? DST_NOPOLICY : 0) |
1227                          (noxfrm ? DST_NOXFRM : 0));
1228 }
1229
1230 /* called in rcu_read_lock() section */
1231 static int ip_route_input_mc(struct sk_buff *skb, __be32 daddr, __be32 saddr,
1232                                 u8 tos, struct net_device *dev, int our)
1233 {
1234         struct rtable *rth;
1235         struct in_device *in_dev = __in_dev_get_rcu(dev);
1236         u32 itag = 0;
1237         int err;
1238
1239         /* Primary sanity checks. */
1240
1241         if (in_dev == NULL)
1242                 return -EINVAL;
1243
1244         if (ipv4_is_multicast(saddr) || ipv4_is_lbcast(saddr) ||
1245             skb->protocol != htons(ETH_P_IP))
1246                 goto e_inval;
1247
1248         if (likely(!IN_DEV_ROUTE_LOCALNET(in_dev)))
1249                 if (ipv4_is_loopback(saddr))
1250                         goto e_inval;
1251
1252         if (ipv4_is_zeronet(saddr)) {
1253                 if (!ipv4_is_local_multicast(daddr))
1254                         goto e_inval;
1255         } else {
1256                 err = fib_validate_source(skb, saddr, 0, tos, 0, dev,
1257                                           in_dev, &itag);
1258                 if (err < 0)
1259                         goto e_err;
1260         }
1261         rth = rt_dst_alloc(dev_net(dev)->loopback_dev,
1262                            IN_DEV_CONF_GET(in_dev, NOPOLICY), false);
1263         if (!rth)
1264                 goto e_nobufs;
1265
1266 #ifdef CONFIG_IP_ROUTE_CLASSID
1267         rth->dst.tclassid = itag;
1268 #endif
1269         rth->dst.output = ip_rt_bug;
1270
1271         rth->rt_genid   = rt_genid(dev_net(dev));
1272         rth->rt_flags   = RTCF_MULTICAST;
1273         rth->rt_type    = RTN_MULTICAST;
1274         rth->rt_route_iif = dev->ifindex;
1275         rth->rt_iif     = dev->ifindex;
1276         rth->rt_oif     = 0;
1277         rth->rt_pmtu    = 0;
1278         rth->rt_gateway = 0;
1279         rth->fi = NULL;
1280         if (our) {
1281                 rth->dst.input= ip_local_deliver;
1282                 rth->rt_flags |= RTCF_LOCAL;
1283         }
1284
1285 #ifdef CONFIG_IP_MROUTE
1286         if (!ipv4_is_local_multicast(daddr) && IN_DEV_MFORWARD(in_dev))
1287                 rth->dst.input = ip_mr_input;
1288 #endif
1289         RT_CACHE_STAT_INC(in_slow_mc);
1290
1291         skb_dst_set(skb, &rth->dst);
1292         return 0;
1293
1294 e_nobufs:
1295         return -ENOBUFS;
1296 e_inval:
1297         return -EINVAL;
1298 e_err:
1299         return err;
1300 }
1301
1302
1303 static void ip_handle_martian_source(struct net_device *dev,
1304                                      struct in_device *in_dev,
1305                                      struct sk_buff *skb,
1306                                      __be32 daddr,
1307                                      __be32 saddr)
1308 {
1309         RT_CACHE_STAT_INC(in_martian_src);
1310 #ifdef CONFIG_IP_ROUTE_VERBOSE
1311         if (IN_DEV_LOG_MARTIANS(in_dev) && net_ratelimit()) {
1312                 /*
1313                  *      RFC1812 recommendation, if source is martian,
1314                  *      the only hint is MAC header.
1315                  */
1316                 pr_warn("martian source %pI4 from %pI4, on dev %s\n",
1317                         &daddr, &saddr, dev->name);
1318                 if (dev->hard_header_len && skb_mac_header_was_set(skb)) {
1319                         print_hex_dump(KERN_WARNING, "ll header: ",
1320                                        DUMP_PREFIX_OFFSET, 16, 1,
1321                                        skb_mac_header(skb),
1322                                        dev->hard_header_len, true);
1323                 }
1324         }
1325 #endif
1326 }
1327
1328 /* called in rcu_read_lock() section */
1329 static int __mkroute_input(struct sk_buff *skb,
1330                            const struct fib_result *res,
1331                            struct in_device *in_dev,
1332                            __be32 daddr, __be32 saddr, u32 tos,
1333                            struct rtable **result)
1334 {
1335         struct rtable *rth;
1336         int err;
1337         struct in_device *out_dev;
1338         unsigned int flags = 0;
1339         u32 itag;
1340
1341         /* get a working reference to the output device */
1342         out_dev = __in_dev_get_rcu(FIB_RES_DEV(*res));
1343         if (out_dev == NULL) {
1344                 net_crit_ratelimited("Bug in ip_route_input_slow(). Please report.\n");
1345                 return -EINVAL;
1346         }
1347
1348
1349         err = fib_validate_source(skb, saddr, daddr, tos, FIB_RES_OIF(*res),
1350                                   in_dev->dev, in_dev, &itag);
1351         if (err < 0) {
1352                 ip_handle_martian_source(in_dev->dev, in_dev, skb, daddr,
1353                                          saddr);
1354
1355                 goto cleanup;
1356         }
1357
1358         if (err)
1359                 flags |= RTCF_DIRECTSRC;
1360
1361         if (out_dev == in_dev && err &&
1362             (IN_DEV_SHARED_MEDIA(out_dev) ||
1363              inet_addr_onlink(out_dev, saddr, FIB_RES_GW(*res))))
1364                 flags |= RTCF_DOREDIRECT;
1365
1366         if (skb->protocol != htons(ETH_P_IP)) {
1367                 /* Not IP (i.e. ARP). Do not create route, if it is
1368                  * invalid for proxy arp. DNAT routes are always valid.
1369                  *
1370                  * Proxy arp feature have been extended to allow, ARP
1371                  * replies back to the same interface, to support
1372                  * Private VLAN switch technologies. See arp.c.
1373                  */
1374                 if (out_dev == in_dev &&
1375                     IN_DEV_PROXY_ARP_PVLAN(in_dev) == 0) {
1376                         err = -EINVAL;
1377                         goto cleanup;
1378                 }
1379         }
1380
1381         rth = rt_dst_alloc(out_dev->dev,
1382                            IN_DEV_CONF_GET(in_dev, NOPOLICY),
1383                            IN_DEV_CONF_GET(out_dev, NOXFRM));
1384         if (!rth) {
1385                 err = -ENOBUFS;
1386                 goto cleanup;
1387         }
1388
1389         rth->rt_genid = rt_genid(dev_net(rth->dst.dev));
1390         rth->rt_flags = flags;
1391         rth->rt_type = res->type;
1392         rth->rt_route_iif = in_dev->dev->ifindex;
1393         rth->rt_iif     = in_dev->dev->ifindex;
1394         rth->rt_oif     = 0;
1395         rth->rt_pmtu    = 0;
1396         rth->rt_gateway = 0;
1397         rth->fi = NULL;
1398
1399         rth->dst.input = ip_forward;
1400         rth->dst.output = ip_output;
1401
1402         rt_set_nexthop(rth, NULL, res, res->fi, res->type, itag);
1403
1404         *result = rth;
1405         err = 0;
1406  cleanup:
1407         return err;
1408 }
1409
1410 static int ip_mkroute_input(struct sk_buff *skb,
1411                             struct fib_result *res,
1412                             const struct flowi4 *fl4,
1413                             struct in_device *in_dev,
1414                             __be32 daddr, __be32 saddr, u32 tos)
1415 {
1416         struct rtable *rth = NULL;
1417         int err;
1418
1419 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1420         if (res->fi && res->fi->fib_nhs > 1)
1421                 fib_select_multipath(res);
1422 #endif
1423
1424         /* create a routing cache entry */
1425         err = __mkroute_input(skb, res, in_dev, daddr, saddr, tos, &rth);
1426         if (err)
1427                 return err;
1428
1429         skb_dst_set(skb, &rth->dst);
1430         return 0;
1431 }
1432
1433 /*
1434  *      NOTE. We drop all the packets that has local source
1435  *      addresses, because every properly looped back packet
1436  *      must have correct destination already attached by output routine.
1437  *
1438  *      Such approach solves two big problems:
1439  *      1. Not simplex devices are handled properly.
1440  *      2. IP spoofing attempts are filtered with 100% of guarantee.
1441  *      called with rcu_read_lock()
1442  */
1443
1444 static int ip_route_input_slow(struct sk_buff *skb, __be32 daddr, __be32 saddr,
1445                                u8 tos, struct net_device *dev)
1446 {
1447         struct fib_result res;
1448         struct in_device *in_dev = __in_dev_get_rcu(dev);
1449         struct flowi4   fl4;
1450         unsigned int    flags = 0;
1451         u32             itag = 0;
1452         struct rtable   *rth;
1453         int             err = -EINVAL;
1454         struct net    *net = dev_net(dev);
1455
1456         /* IP on this device is disabled. */
1457
1458         if (!in_dev)
1459                 goto out;
1460
1461         /* Check for the most weird martians, which can be not detected
1462            by fib_lookup.
1463          */
1464
1465         if (ipv4_is_multicast(saddr) || ipv4_is_lbcast(saddr))
1466                 goto martian_source;
1467
1468         if (ipv4_is_lbcast(daddr) || (saddr == 0 && daddr == 0))
1469                 goto brd_input;
1470
1471         /* Accept zero addresses only to limited broadcast;
1472          * I even do not know to fix it or not. Waiting for complains :-)
1473          */
1474         if (ipv4_is_zeronet(saddr))
1475                 goto martian_source;
1476
1477         if (ipv4_is_zeronet(daddr))
1478                 goto martian_destination;
1479
1480         if (likely(!IN_DEV_ROUTE_LOCALNET(in_dev))) {
1481                 if (ipv4_is_loopback(daddr))
1482                         goto martian_destination;
1483
1484                 if (ipv4_is_loopback(saddr))
1485                         goto martian_source;
1486         }
1487
1488         /*
1489          *      Now we are ready to route packet.
1490          */
1491         fl4.flowi4_oif = 0;
1492         fl4.flowi4_iif = dev->ifindex;
1493         fl4.flowi4_mark = skb->mark;
1494         fl4.flowi4_tos = tos;
1495         fl4.flowi4_scope = RT_SCOPE_UNIVERSE;
1496         fl4.daddr = daddr;
1497         fl4.saddr = saddr;
1498         err = fib_lookup(net, &fl4, &res);
1499         if (err != 0)
1500                 goto no_route;
1501
1502         RT_CACHE_STAT_INC(in_slow_tot);
1503
1504         if (res.type == RTN_BROADCAST)
1505                 goto brd_input;
1506
1507         if (res.type == RTN_LOCAL) {
1508                 err = fib_validate_source(skb, saddr, daddr, tos,
1509                                           net->loopback_dev->ifindex,
1510                                           dev, in_dev, &itag);
1511                 if (err < 0)
1512                         goto martian_source_keep_err;
1513                 if (err)
1514                         flags |= RTCF_DIRECTSRC;
1515                 goto local_input;
1516         }
1517
1518         if (!IN_DEV_FORWARD(in_dev))
1519                 goto no_route;
1520         if (res.type != RTN_UNICAST)
1521                 goto martian_destination;
1522
1523         err = ip_mkroute_input(skb, &res, &fl4, in_dev, daddr, saddr, tos);
1524 out:    return err;
1525
1526 brd_input:
1527         if (skb->protocol != htons(ETH_P_IP))
1528                 goto e_inval;
1529
1530         if (!ipv4_is_zeronet(saddr)) {
1531                 err = fib_validate_source(skb, saddr, 0, tos, 0, dev,
1532                                           in_dev, &itag);
1533                 if (err < 0)
1534                         goto martian_source_keep_err;
1535                 if (err)
1536                         flags |= RTCF_DIRECTSRC;
1537         }
1538         flags |= RTCF_BROADCAST;
1539         res.type = RTN_BROADCAST;
1540         RT_CACHE_STAT_INC(in_brd);
1541
1542 local_input:
1543         rth = rt_dst_alloc(net->loopback_dev,
1544                            IN_DEV_CONF_GET(in_dev, NOPOLICY), false);
1545         if (!rth)
1546                 goto e_nobufs;
1547
1548         rth->dst.input= ip_local_deliver;
1549         rth->dst.output= ip_rt_bug;
1550 #ifdef CONFIG_IP_ROUTE_CLASSID
1551         rth->dst.tclassid = itag;
1552 #endif
1553
1554         rth->rt_genid = rt_genid(net);
1555         rth->rt_flags   = flags|RTCF_LOCAL;
1556         rth->rt_type    = res.type;
1557         rth->rt_route_iif = dev->ifindex;
1558         rth->rt_iif     = dev->ifindex;
1559         rth->rt_oif     = 0;
1560         rth->rt_pmtu    = 0;
1561         rth->rt_gateway = 0;
1562         rth->fi = NULL;
1563         if (res.type == RTN_UNREACHABLE) {
1564                 rth->dst.input= ip_error;
1565                 rth->dst.error= -err;
1566                 rth->rt_flags   &= ~RTCF_LOCAL;
1567         }
1568         skb_dst_set(skb, &rth->dst);
1569         err = 0;
1570         goto out;
1571
1572 no_route:
1573         RT_CACHE_STAT_INC(in_no_route);
1574         res.type = RTN_UNREACHABLE;
1575         if (err == -ESRCH)
1576                 err = -ENETUNREACH;
1577         goto local_input;
1578
1579         /*
1580          *      Do not cache martian addresses: they should be logged (RFC1812)
1581          */
1582 martian_destination:
1583         RT_CACHE_STAT_INC(in_martian_dst);
1584 #ifdef CONFIG_IP_ROUTE_VERBOSE
1585         if (IN_DEV_LOG_MARTIANS(in_dev))
1586                 net_warn_ratelimited("martian destination %pI4 from %pI4, dev %s\n",
1587                                      &daddr, &saddr, dev->name);
1588 #endif
1589
1590 e_inval:
1591         err = -EINVAL;
1592         goto out;
1593
1594 e_nobufs:
1595         err = -ENOBUFS;
1596         goto out;
1597
1598 martian_source:
1599         err = -EINVAL;
1600 martian_source_keep_err:
1601         ip_handle_martian_source(dev, in_dev, skb, daddr, saddr);
1602         goto out;
1603 }
1604
1605 int ip_route_input(struct sk_buff *skb, __be32 daddr, __be32 saddr,
1606                    u8 tos, struct net_device *dev)
1607 {
1608         int res;
1609
1610         rcu_read_lock();
1611
1612         /* Multicast recognition logic is moved from route cache to here.
1613            The problem was that too many Ethernet cards have broken/missing
1614            hardware multicast filters :-( As result the host on multicasting
1615            network acquires a lot of useless route cache entries, sort of
1616            SDR messages from all the world. Now we try to get rid of them.
1617            Really, provided software IP multicast filter is organized
1618            reasonably (at least, hashed), it does not result in a slowdown
1619            comparing with route cache reject entries.
1620            Note, that multicast routers are not affected, because
1621            route cache entry is created eventually.
1622          */
1623         if (ipv4_is_multicast(daddr)) {
1624                 struct in_device *in_dev = __in_dev_get_rcu(dev);
1625
1626                 if (in_dev) {
1627                         int our = ip_check_mc_rcu(in_dev, daddr, saddr,
1628                                                   ip_hdr(skb)->protocol);
1629                         if (our
1630 #ifdef CONFIG_IP_MROUTE
1631                                 ||
1632                             (!ipv4_is_local_multicast(daddr) &&
1633                              IN_DEV_MFORWARD(in_dev))
1634 #endif
1635                            ) {
1636                                 int res = ip_route_input_mc(skb, daddr, saddr,
1637                                                             tos, dev, our);
1638                                 rcu_read_unlock();
1639                                 return res;
1640                         }
1641                 }
1642                 rcu_read_unlock();
1643                 return -EINVAL;
1644         }
1645         res = ip_route_input_slow(skb, daddr, saddr, tos, dev);
1646         rcu_read_unlock();
1647         return res;
1648 }
1649 EXPORT_SYMBOL(ip_route_input);
1650
1651 /* called with rcu_read_lock() */
1652 static struct rtable *__mkroute_output(const struct fib_result *res,
1653                                        const struct flowi4 *fl4, int orig_oif,
1654                                        struct net_device *dev_out,
1655                                        unsigned int flags)
1656 {
1657         struct fib_info *fi = res->fi;
1658         struct in_device *in_dev;
1659         u16 type = res->type;
1660         struct rtable *rth;
1661
1662         in_dev = __in_dev_get_rcu(dev_out);
1663         if (!in_dev)
1664                 return ERR_PTR(-EINVAL);
1665
1666         if (likely(!IN_DEV_ROUTE_LOCALNET(in_dev)))
1667                 if (ipv4_is_loopback(fl4->saddr) && !(dev_out->flags & IFF_LOOPBACK))
1668                         return ERR_PTR(-EINVAL);
1669
1670         if (ipv4_is_lbcast(fl4->daddr))
1671                 type = RTN_BROADCAST;
1672         else if (ipv4_is_multicast(fl4->daddr))
1673                 type = RTN_MULTICAST;
1674         else if (ipv4_is_zeronet(fl4->daddr))
1675                 return ERR_PTR(-EINVAL);
1676
1677         if (dev_out->flags & IFF_LOOPBACK)
1678                 flags |= RTCF_LOCAL;
1679
1680         if (type == RTN_BROADCAST) {
1681                 flags |= RTCF_BROADCAST | RTCF_LOCAL;
1682                 fi = NULL;
1683         } else if (type == RTN_MULTICAST) {
1684                 flags |= RTCF_MULTICAST | RTCF_LOCAL;
1685                 if (!ip_check_mc_rcu(in_dev, fl4->daddr, fl4->saddr,
1686                                      fl4->flowi4_proto))
1687                         flags &= ~RTCF_LOCAL;
1688                 /* If multicast route do not exist use
1689                  * default one, but do not gateway in this case.
1690                  * Yes, it is hack.
1691                  */
1692                 if (fi && res->prefixlen < 4)
1693                         fi = NULL;
1694         }
1695
1696         rth = rt_dst_alloc(dev_out,
1697                            IN_DEV_CONF_GET(in_dev, NOPOLICY),
1698                            IN_DEV_CONF_GET(in_dev, NOXFRM));
1699         if (!rth)
1700                 return ERR_PTR(-ENOBUFS);
1701
1702         rth->dst.output = ip_output;
1703
1704         rth->rt_genid = rt_genid(dev_net(dev_out));
1705         rth->rt_flags   = flags;
1706         rth->rt_type    = type;
1707         rth->rt_route_iif = 0;
1708         rth->rt_iif     = orig_oif ? : dev_out->ifindex;
1709         rth->rt_oif     = orig_oif;
1710         rth->rt_pmtu    = 0;
1711         rth->rt_gateway = 0;
1712         rth->fi = NULL;
1713
1714         RT_CACHE_STAT_INC(out_slow_tot);
1715
1716         if (flags & RTCF_LOCAL)
1717                 rth->dst.input = ip_local_deliver;
1718         if (flags & (RTCF_BROADCAST | RTCF_MULTICAST)) {
1719                 if (flags & RTCF_LOCAL &&
1720                     !(dev_out->flags & IFF_LOOPBACK)) {
1721                         rth->dst.output = ip_mc_output;
1722                         RT_CACHE_STAT_INC(out_slow_mc);
1723                 }
1724 #ifdef CONFIG_IP_MROUTE
1725                 if (type == RTN_MULTICAST) {
1726                         if (IN_DEV_MFORWARD(in_dev) &&
1727                             !ipv4_is_local_multicast(fl4->daddr)) {
1728                                 rth->dst.input = ip_mr_input;
1729                                 rth->dst.output = ip_mc_output;
1730                         }
1731                 }
1732 #endif
1733         }
1734
1735         rt_set_nexthop(rth, fl4, res, fi, type, 0);
1736
1737         if (fl4->flowi4_flags & FLOWI_FLAG_RT_NOCACHE)
1738                 rth->dst.flags |= DST_NOCACHE;
1739
1740         return rth;
1741 }
1742
1743 /*
1744  * Major route resolver routine.
1745  */
1746
1747 struct rtable *__ip_route_output_key(struct net *net, struct flowi4 *fl4)
1748 {
1749         struct net_device *dev_out = NULL;
1750         __u8 tos = RT_FL_TOS(fl4);
1751         unsigned int flags = 0;
1752         struct fib_result res;
1753         struct rtable *rth;
1754         int orig_oif;
1755
1756         res.tclassid    = 0;
1757         res.fi          = NULL;
1758         res.table       = NULL;
1759
1760         orig_oif = fl4->flowi4_oif;
1761
1762         fl4->flowi4_iif = net->loopback_dev->ifindex;
1763         fl4->flowi4_tos = tos & IPTOS_RT_MASK;
1764         fl4->flowi4_scope = ((tos & RTO_ONLINK) ?
1765                          RT_SCOPE_LINK : RT_SCOPE_UNIVERSE);
1766
1767         rcu_read_lock();
1768         if (fl4->saddr) {
1769                 rth = ERR_PTR(-EINVAL);
1770                 if (ipv4_is_multicast(fl4->saddr) ||
1771                     ipv4_is_lbcast(fl4->saddr) ||
1772                     ipv4_is_zeronet(fl4->saddr))
1773                         goto out;
1774
1775                 /* I removed check for oif == dev_out->oif here.
1776                    It was wrong for two reasons:
1777                    1. ip_dev_find(net, saddr) can return wrong iface, if saddr
1778                       is assigned to multiple interfaces.
1779                    2. Moreover, we are allowed to send packets with saddr
1780                       of another iface. --ANK
1781                  */
1782
1783                 if (fl4->flowi4_oif == 0 &&
1784                     (ipv4_is_multicast(fl4->daddr) ||
1785                      ipv4_is_lbcast(fl4->daddr))) {
1786                         /* It is equivalent to inet_addr_type(saddr) == RTN_LOCAL */
1787                         dev_out = __ip_dev_find(net, fl4->saddr, false);
1788                         if (dev_out == NULL)
1789                                 goto out;
1790
1791                         /* Special hack: user can direct multicasts
1792                            and limited broadcast via necessary interface
1793                            without fiddling with IP_MULTICAST_IF or IP_PKTINFO.
1794                            This hack is not just for fun, it allows
1795                            vic,vat and friends to work.
1796                            They bind socket to loopback, set ttl to zero
1797                            and expect that it will work.
1798                            From the viewpoint of routing cache they are broken,
1799                            because we are not allowed to build multicast path
1800                            with loopback source addr (look, routing cache
1801                            cannot know, that ttl is zero, so that packet
1802                            will not leave this host and route is valid).
1803                            Luckily, this hack is good workaround.
1804                          */
1805
1806                         fl4->flowi4_oif = dev_out->ifindex;
1807                         goto make_route;
1808                 }
1809
1810                 if (!(fl4->flowi4_flags & FLOWI_FLAG_ANYSRC)) {
1811                         /* It is equivalent to inet_addr_type(saddr) == RTN_LOCAL */
1812                         if (!__ip_dev_find(net, fl4->saddr, false))
1813                                 goto out;
1814                 }
1815         }
1816
1817
1818         if (fl4->flowi4_oif) {
1819                 dev_out = dev_get_by_index_rcu(net, fl4->flowi4_oif);
1820                 rth = ERR_PTR(-ENODEV);
1821                 if (dev_out == NULL)
1822                         goto out;
1823
1824                 /* RACE: Check return value of inet_select_addr instead. */
1825                 if (!(dev_out->flags & IFF_UP) || !__in_dev_get_rcu(dev_out)) {
1826                         rth = ERR_PTR(-ENETUNREACH);
1827                         goto out;
1828                 }
1829                 if (ipv4_is_local_multicast(fl4->daddr) ||
1830                     ipv4_is_lbcast(fl4->daddr)) {
1831                         if (!fl4->saddr)
1832                                 fl4->saddr = inet_select_addr(dev_out, 0,
1833                                                               RT_SCOPE_LINK);
1834                         goto make_route;
1835                 }
1836                 if (fl4->saddr) {
1837                         if (ipv4_is_multicast(fl4->daddr))
1838                                 fl4->saddr = inet_select_addr(dev_out, 0,
1839                                                               fl4->flowi4_scope);
1840                         else if (!fl4->daddr)
1841                                 fl4->saddr = inet_select_addr(dev_out, 0,
1842                                                               RT_SCOPE_HOST);
1843                 }
1844         }
1845
1846         if (!fl4->daddr) {
1847                 fl4->daddr = fl4->saddr;
1848                 if (!fl4->daddr)
1849                         fl4->daddr = fl4->saddr = htonl(INADDR_LOOPBACK);
1850                 dev_out = net->loopback_dev;
1851                 fl4->flowi4_oif = net->loopback_dev->ifindex;
1852                 res.type = RTN_LOCAL;
1853                 flags |= RTCF_LOCAL;
1854                 goto make_route;
1855         }
1856
1857         if (fib_lookup(net, fl4, &res)) {
1858                 res.fi = NULL;
1859                 res.table = NULL;
1860                 if (fl4->flowi4_oif) {
1861                         /* Apparently, routing tables are wrong. Assume,
1862                            that the destination is on link.
1863
1864                            WHY? DW.
1865                            Because we are allowed to send to iface
1866                            even if it has NO routes and NO assigned
1867                            addresses. When oif is specified, routing
1868                            tables are looked up with only one purpose:
1869                            to catch if destination is gatewayed, rather than
1870                            direct. Moreover, if MSG_DONTROUTE is set,
1871                            we send packet, ignoring both routing tables
1872                            and ifaddr state. --ANK
1873
1874
1875                            We could make it even if oif is unknown,
1876                            likely IPv6, but we do not.
1877                          */
1878
1879                         if (fl4->saddr == 0)
1880                                 fl4->saddr = inet_select_addr(dev_out, 0,
1881                                                               RT_SCOPE_LINK);
1882                         res.type = RTN_UNICAST;
1883                         goto make_route;
1884                 }
1885                 rth = ERR_PTR(-ENETUNREACH);
1886                 goto out;
1887         }
1888
1889         if (res.type == RTN_LOCAL) {
1890                 if (!fl4->saddr) {
1891                         if (res.fi->fib_prefsrc)
1892                                 fl4->saddr = res.fi->fib_prefsrc;
1893                         else
1894                                 fl4->saddr = fl4->daddr;
1895                 }
1896                 dev_out = net->loopback_dev;
1897                 fl4->flowi4_oif = dev_out->ifindex;
1898                 res.fi = NULL;
1899                 flags |= RTCF_LOCAL;
1900                 goto make_route;
1901         }
1902
1903 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1904         if (res.fi->fib_nhs > 1 && fl4->flowi4_oif == 0)
1905                 fib_select_multipath(&res);
1906         else
1907 #endif
1908         if (!res.prefixlen &&
1909             res.table->tb_num_default > 1 &&
1910             res.type == RTN_UNICAST && !fl4->flowi4_oif)
1911                 fib_select_default(&res);
1912
1913         if (!fl4->saddr)
1914                 fl4->saddr = FIB_RES_PREFSRC(net, res);
1915
1916         dev_out = FIB_RES_DEV(res);
1917         fl4->flowi4_oif = dev_out->ifindex;
1918
1919
1920 make_route:
1921         rth = __mkroute_output(&res, fl4, orig_oif, dev_out, flags);
1922
1923 out:
1924         rcu_read_unlock();
1925         return rth;
1926 }
1927 EXPORT_SYMBOL_GPL(__ip_route_output_key);
1928
1929 static struct dst_entry *ipv4_blackhole_dst_check(struct dst_entry *dst, u32 cookie)
1930 {
1931         return NULL;
1932 }
1933
1934 static unsigned int ipv4_blackhole_mtu(const struct dst_entry *dst)
1935 {
1936         unsigned int mtu = dst_metric_raw(dst, RTAX_MTU);
1937
1938         return mtu ? : dst->dev->mtu;
1939 }
1940
1941 static void ipv4_rt_blackhole_update_pmtu(struct dst_entry *dst, struct sock *sk,
1942                                           struct sk_buff *skb, u32 mtu)
1943 {
1944 }
1945
1946 static void ipv4_rt_blackhole_redirect(struct dst_entry *dst, struct sock *sk,
1947                                        struct sk_buff *skb)
1948 {
1949 }
1950
1951 static u32 *ipv4_rt_blackhole_cow_metrics(struct dst_entry *dst,
1952                                           unsigned long old)
1953 {
1954         return NULL;
1955 }
1956
1957 static struct dst_ops ipv4_dst_blackhole_ops = {
1958         .family                 =       AF_INET,
1959         .protocol               =       cpu_to_be16(ETH_P_IP),
1960         .destroy                =       ipv4_dst_destroy,
1961         .check                  =       ipv4_blackhole_dst_check,
1962         .mtu                    =       ipv4_blackhole_mtu,
1963         .default_advmss         =       ipv4_default_advmss,
1964         .update_pmtu            =       ipv4_rt_blackhole_update_pmtu,
1965         .redirect               =       ipv4_rt_blackhole_redirect,
1966         .cow_metrics            =       ipv4_rt_blackhole_cow_metrics,
1967         .neigh_lookup           =       ipv4_neigh_lookup,
1968 };
1969
1970 struct dst_entry *ipv4_blackhole_route(struct net *net, struct dst_entry *dst_orig)
1971 {
1972         struct rtable *rt = dst_alloc(&ipv4_dst_blackhole_ops, NULL, 1, 0, 0);
1973         struct rtable *ort = (struct rtable *) dst_orig;
1974
1975         if (rt) {
1976                 struct dst_entry *new = &rt->dst;
1977
1978                 new->__use = 1;
1979                 new->input = dst_discard;
1980                 new->output = dst_discard;
1981
1982                 new->dev = ort->dst.dev;
1983                 if (new->dev)
1984                         dev_hold(new->dev);
1985
1986                 rt->rt_route_iif = ort->rt_route_iif;
1987                 rt->rt_iif = ort->rt_iif;
1988                 rt->rt_oif = ort->rt_oif;
1989                 rt->rt_pmtu = ort->rt_pmtu;
1990
1991                 rt->rt_genid = rt_genid(net);
1992                 rt->rt_flags = ort->rt_flags;
1993                 rt->rt_type = ort->rt_type;
1994                 rt->rt_gateway = ort->rt_gateway;
1995                 rt->fi = ort->fi;
1996                 if (rt->fi)
1997                         atomic_inc(&rt->fi->fib_clntref);
1998
1999                 dst_free(new);
2000         }
2001
2002         dst_release(dst_orig);
2003
2004         return rt ? &rt->dst : ERR_PTR(-ENOMEM);
2005 }
2006
2007 struct rtable *ip_route_output_flow(struct net *net, struct flowi4 *flp4,
2008                                     struct sock *sk)
2009 {
2010         struct rtable *rt = __ip_route_output_key(net, flp4);
2011
2012         if (IS_ERR(rt))
2013                 return rt;
2014
2015         if (flp4->flowi4_proto)
2016                 rt = (struct rtable *) xfrm_lookup(net, &rt->dst,
2017                                                    flowi4_to_flowi(flp4),
2018                                                    sk, 0);
2019
2020         return rt;
2021 }
2022 EXPORT_SYMBOL_GPL(ip_route_output_flow);
2023
2024 static int rt_fill_info(struct net *net,  __be32 dst, __be32 src,
2025                         struct flowi4 *fl4, struct sk_buff *skb, u32 pid,
2026                         u32 seq, int event, int nowait, unsigned int flags)
2027 {
2028         struct rtable *rt = skb_rtable(skb);
2029         struct rtmsg *r;
2030         struct nlmsghdr *nlh;
2031         unsigned long expires = 0;
2032         u32 error;
2033         u32 metrics[RTAX_MAX];
2034
2035         nlh = nlmsg_put(skb, pid, seq, event, sizeof(*r), flags);
2036         if (nlh == NULL)
2037                 return -EMSGSIZE;
2038
2039         r = nlmsg_data(nlh);
2040         r->rtm_family    = AF_INET;
2041         r->rtm_dst_len  = 32;
2042         r->rtm_src_len  = 0;
2043         r->rtm_tos      = fl4->flowi4_tos;
2044         r->rtm_table    = RT_TABLE_MAIN;
2045         if (nla_put_u32(skb, RTA_TABLE, RT_TABLE_MAIN))
2046                 goto nla_put_failure;
2047         r->rtm_type     = rt->rt_type;
2048         r->rtm_scope    = RT_SCOPE_UNIVERSE;
2049         r->rtm_protocol = RTPROT_UNSPEC;
2050         r->rtm_flags    = (rt->rt_flags & ~0xFFFF) | RTM_F_CLONED;
2051         if (rt->rt_flags & RTCF_NOTIFY)
2052                 r->rtm_flags |= RTM_F_NOTIFY;
2053
2054         if (nla_put_be32(skb, RTA_DST, dst))
2055                 goto nla_put_failure;
2056         if (src) {
2057                 r->rtm_src_len = 32;
2058                 if (nla_put_be32(skb, RTA_SRC, src))
2059                         goto nla_put_failure;
2060         }
2061         if (rt->dst.dev &&
2062             nla_put_u32(skb, RTA_OIF, rt->dst.dev->ifindex))
2063                 goto nla_put_failure;
2064 #ifdef CONFIG_IP_ROUTE_CLASSID
2065         if (rt->dst.tclassid &&
2066             nla_put_u32(skb, RTA_FLOW, rt->dst.tclassid))
2067                 goto nla_put_failure;
2068 #endif
2069         if (!rt_is_input_route(rt) &&
2070             fl4->saddr != src) {
2071                 if (nla_put_be32(skb, RTA_PREFSRC, fl4->saddr))
2072                         goto nla_put_failure;
2073         }
2074         if (rt->rt_gateway &&
2075             nla_put_be32(skb, RTA_GATEWAY, rt->rt_gateway))
2076                 goto nla_put_failure;
2077
2078         memcpy(metrics, dst_metrics_ptr(&rt->dst), sizeof(metrics));
2079         if (rt->rt_pmtu)
2080                 metrics[RTAX_MTU - 1] = rt->rt_pmtu;
2081         if (rtnetlink_put_metrics(skb, metrics) < 0)
2082                 goto nla_put_failure;
2083
2084         if (fl4->flowi4_mark &&
2085             nla_put_be32(skb, RTA_MARK, fl4->flowi4_mark))
2086                 goto nla_put_failure;
2087
2088         error = rt->dst.error;
2089         expires = rt->dst.expires;
2090         if (expires) {
2091                 if (time_before(jiffies, expires))
2092                         expires -= jiffies;
2093                 else
2094                         expires = 0;
2095         }
2096
2097         if (rt_is_input_route(rt)) {
2098                 if (nla_put_u32(skb, RTA_IIF, rt->rt_iif))
2099                         goto nla_put_failure;
2100         }
2101
2102         if (rtnl_put_cacheinfo(skb, &rt->dst, 0, expires, error) < 0)
2103                 goto nla_put_failure;
2104
2105         return nlmsg_end(skb, nlh);
2106
2107 nla_put_failure:
2108         nlmsg_cancel(skb, nlh);
2109         return -EMSGSIZE;
2110 }
2111
2112 static int inet_rtm_getroute(struct sk_buff *in_skb, struct nlmsghdr *nlh, void *arg)
2113 {
2114         struct net *net = sock_net(in_skb->sk);
2115         struct rtmsg *rtm;
2116         struct nlattr *tb[RTA_MAX+1];
2117         struct rtable *rt = NULL;
2118         struct flowi4 fl4;
2119         __be32 dst = 0;
2120         __be32 src = 0;
2121         u32 iif;
2122         int err;
2123         int mark;
2124         struct sk_buff *skb;
2125
2126         err = nlmsg_parse(nlh, sizeof(*rtm), tb, RTA_MAX, rtm_ipv4_policy);
2127         if (err < 0)
2128                 goto errout;
2129
2130         rtm = nlmsg_data(nlh);
2131
2132         skb = alloc_skb(NLMSG_GOODSIZE, GFP_KERNEL);
2133         if (skb == NULL) {
2134                 err = -ENOBUFS;
2135                 goto errout;
2136         }
2137
2138         /* Reserve room for dummy headers, this skb can pass
2139            through good chunk of routing engine.
2140          */
2141         skb_reset_mac_header(skb);
2142         skb_reset_network_header(skb);
2143
2144         /* Bugfix: need to give ip_route_input enough of an IP header to not gag. */
2145         ip_hdr(skb)->protocol = IPPROTO_ICMP;
2146         skb_reserve(skb, MAX_HEADER + sizeof(struct iphdr));
2147
2148         src = tb[RTA_SRC] ? nla_get_be32(tb[RTA_SRC]) : 0;
2149         dst = tb[RTA_DST] ? nla_get_be32(tb[RTA_DST]) : 0;
2150         iif = tb[RTA_IIF] ? nla_get_u32(tb[RTA_IIF]) : 0;
2151         mark = tb[RTA_MARK] ? nla_get_u32(tb[RTA_MARK]) : 0;
2152
2153         memset(&fl4, 0, sizeof(fl4));
2154         fl4.daddr = dst;
2155         fl4.saddr = src;
2156         fl4.flowi4_tos = rtm->rtm_tos;
2157         fl4.flowi4_oif = tb[RTA_OIF] ? nla_get_u32(tb[RTA_OIF]) : 0;
2158         fl4.flowi4_mark = mark;
2159
2160         if (iif) {
2161                 struct net_device *dev;
2162
2163                 dev = __dev_get_by_index(net, iif);
2164                 if (dev == NULL) {
2165                         err = -ENODEV;
2166                         goto errout_free;
2167                 }
2168
2169                 skb->protocol   = htons(ETH_P_IP);
2170                 skb->dev        = dev;
2171                 skb->mark       = mark;
2172                 local_bh_disable();
2173                 err = ip_route_input(skb, dst, src, rtm->rtm_tos, dev);
2174                 local_bh_enable();
2175
2176                 rt = skb_rtable(skb);
2177                 if (err == 0 && rt->dst.error)
2178                         err = -rt->dst.error;
2179         } else {
2180                 rt = ip_route_output_key(net, &fl4);
2181
2182                 err = 0;
2183                 if (IS_ERR(rt))
2184                         err = PTR_ERR(rt);
2185         }
2186
2187         if (err)
2188                 goto errout_free;
2189
2190         skb_dst_set(skb, &rt->dst);
2191         if (rtm->rtm_flags & RTM_F_NOTIFY)
2192                 rt->rt_flags |= RTCF_NOTIFY;
2193
2194         err = rt_fill_info(net, dst, src, &fl4, skb,
2195                            NETLINK_CB(in_skb).pid, nlh->nlmsg_seq,
2196                            RTM_NEWROUTE, 0, 0);
2197         if (err <= 0)
2198                 goto errout_free;
2199
2200         err = rtnl_unicast(skb, net, NETLINK_CB(in_skb).pid);
2201 errout:
2202         return err;
2203
2204 errout_free:
2205         kfree_skb(skb);
2206         goto errout;
2207 }
2208
2209 int ip_rt_dump(struct sk_buff *skb,  struct netlink_callback *cb)
2210 {
2211         return skb->len;
2212 }
2213
2214 void ip_rt_multicast_event(struct in_device *in_dev)
2215 {
2216         rt_cache_flush(dev_net(in_dev->dev), 0);
2217 }
2218
2219 #ifdef CONFIG_SYSCTL
2220 static int ipv4_sysctl_rtcache_flush(ctl_table *__ctl, int write,
2221                                         void __user *buffer,
2222                                         size_t *lenp, loff_t *ppos)
2223 {
2224         if (write) {
2225                 int flush_delay;
2226                 ctl_table ctl;
2227                 struct net *net;
2228
2229                 memcpy(&ctl, __ctl, sizeof(ctl));
2230                 ctl.data = &flush_delay;
2231                 proc_dointvec(&ctl, write, buffer, lenp, ppos);
2232
2233                 net = (struct net *)__ctl->extra1;
2234                 rt_cache_flush(net, flush_delay);
2235                 return 0;
2236         }
2237
2238         return -EINVAL;
2239 }
2240
2241 static ctl_table ipv4_route_table[] = {
2242         {
2243                 .procname       = "gc_thresh",
2244                 .data           = &ipv4_dst_ops.gc_thresh,
2245                 .maxlen         = sizeof(int),
2246                 .mode           = 0644,
2247                 .proc_handler   = proc_dointvec,
2248         },
2249         {
2250                 .procname       = "max_size",
2251                 .data           = &ip_rt_max_size,
2252                 .maxlen         = sizeof(int),
2253                 .mode           = 0644,
2254                 .proc_handler   = proc_dointvec,
2255         },
2256         {
2257                 /*  Deprecated. Use gc_min_interval_ms */
2258
2259                 .procname       = "gc_min_interval",
2260                 .data           = &ip_rt_gc_min_interval,
2261                 .maxlen         = sizeof(int),
2262                 .mode           = 0644,
2263                 .proc_handler   = proc_dointvec_jiffies,
2264         },
2265         {
2266                 .procname       = "gc_min_interval_ms",
2267                 .data           = &ip_rt_gc_min_interval,
2268                 .maxlen         = sizeof(int),
2269                 .mode           = 0644,
2270                 .proc_handler   = proc_dointvec_ms_jiffies,
2271         },
2272         {
2273                 .procname       = "gc_timeout",
2274                 .data           = &ip_rt_gc_timeout,
2275                 .maxlen         = sizeof(int),
2276                 .mode           = 0644,
2277                 .proc_handler   = proc_dointvec_jiffies,
2278         },
2279         {
2280                 .procname       = "gc_interval",
2281                 .data           = &ip_rt_gc_interval,
2282                 .maxlen         = sizeof(int),
2283                 .mode           = 0644,
2284                 .proc_handler   = proc_dointvec_jiffies,
2285         },
2286         {
2287                 .procname       = "redirect_load",
2288                 .data           = &ip_rt_redirect_load,
2289                 .maxlen         = sizeof(int),
2290                 .mode           = 0644,
2291                 .proc_handler   = proc_dointvec,
2292         },
2293         {
2294                 .procname       = "redirect_number",
2295                 .data           = &ip_rt_redirect_number,
2296                 .maxlen         = sizeof(int),
2297                 .mode           = 0644,
2298                 .proc_handler   = proc_dointvec,
2299         },
2300         {
2301                 .procname       = "redirect_silence",
2302                 .data           = &ip_rt_redirect_silence,
2303                 .maxlen         = sizeof(int),
2304                 .mode           = 0644,
2305                 .proc_handler   = proc_dointvec,
2306         },
2307         {
2308                 .procname       = "error_cost",
2309                 .data           = &ip_rt_error_cost,
2310                 .maxlen         = sizeof(int),
2311                 .mode           = 0644,
2312                 .proc_handler   = proc_dointvec,
2313         },
2314         {
2315                 .procname       = "error_burst",
2316                 .data           = &ip_rt_error_burst,
2317                 .maxlen         = sizeof(int),
2318                 .mode           = 0644,
2319                 .proc_handler   = proc_dointvec,
2320         },
2321         {
2322                 .procname       = "gc_elasticity",
2323                 .data           = &ip_rt_gc_elasticity,
2324                 .maxlen         = sizeof(int),
2325                 .mode           = 0644,
2326                 .proc_handler   = proc_dointvec,
2327         },
2328         {
2329                 .procname       = "mtu_expires",
2330                 .data           = &ip_rt_mtu_expires,
2331                 .maxlen         = sizeof(int),
2332                 .mode           = 0644,
2333                 .proc_handler   = proc_dointvec_jiffies,
2334         },
2335         {
2336                 .procname       = "min_pmtu",
2337                 .data           = &ip_rt_min_pmtu,
2338                 .maxlen         = sizeof(int),
2339                 .mode           = 0644,
2340                 .proc_handler   = proc_dointvec,
2341         },
2342         {
2343                 .procname       = "min_adv_mss",
2344                 .data           = &ip_rt_min_advmss,
2345                 .maxlen         = sizeof(int),
2346                 .mode           = 0644,
2347                 .proc_handler   = proc_dointvec,
2348         },
2349         { }
2350 };
2351
2352 static struct ctl_table ipv4_route_flush_table[] = {
2353         {
2354                 .procname       = "flush",
2355                 .maxlen         = sizeof(int),
2356                 .mode           = 0200,
2357                 .proc_handler   = ipv4_sysctl_rtcache_flush,
2358         },
2359         { },
2360 };
2361
2362 static __net_init int sysctl_route_net_init(struct net *net)
2363 {
2364         struct ctl_table *tbl;
2365
2366         tbl = ipv4_route_flush_table;
2367         if (!net_eq(net, &init_net)) {
2368                 tbl = kmemdup(tbl, sizeof(ipv4_route_flush_table), GFP_KERNEL);
2369                 if (tbl == NULL)
2370                         goto err_dup;
2371         }
2372         tbl[0].extra1 = net;
2373
2374         net->ipv4.route_hdr = register_net_sysctl(net, "net/ipv4/route", tbl);
2375         if (net->ipv4.route_hdr == NULL)
2376                 goto err_reg;
2377         return 0;
2378
2379 err_reg:
2380         if (tbl != ipv4_route_flush_table)
2381                 kfree(tbl);
2382 err_dup:
2383         return -ENOMEM;
2384 }
2385
2386 static __net_exit void sysctl_route_net_exit(struct net *net)
2387 {
2388         struct ctl_table *tbl;
2389
2390         tbl = net->ipv4.route_hdr->ctl_table_arg;
2391         unregister_net_sysctl_table(net->ipv4.route_hdr);
2392         BUG_ON(tbl == ipv4_route_flush_table);
2393         kfree(tbl);
2394 }
2395
2396 static __net_initdata struct pernet_operations sysctl_route_ops = {
2397         .init = sysctl_route_net_init,
2398         .exit = sysctl_route_net_exit,
2399 };
2400 #endif
2401
2402 static __net_init int rt_genid_init(struct net *net)
2403 {
2404         get_random_bytes(&net->ipv4.rt_genid,
2405                          sizeof(net->ipv4.rt_genid));
2406         get_random_bytes(&net->ipv4.dev_addr_genid,
2407                          sizeof(net->ipv4.dev_addr_genid));
2408         return 0;
2409 }
2410
2411 static __net_initdata struct pernet_operations rt_genid_ops = {
2412         .init = rt_genid_init,
2413 };
2414
2415 static int __net_init ipv4_inetpeer_init(struct net *net)
2416 {
2417         struct inet_peer_base *bp = kmalloc(sizeof(*bp), GFP_KERNEL);
2418
2419         if (!bp)
2420                 return -ENOMEM;
2421         inet_peer_base_init(bp);
2422         net->ipv4.peers = bp;
2423         return 0;
2424 }
2425
2426 static void __net_exit ipv4_inetpeer_exit(struct net *net)
2427 {
2428         struct inet_peer_base *bp = net->ipv4.peers;
2429
2430         net->ipv4.peers = NULL;
2431         inetpeer_invalidate_tree(bp);
2432         kfree(bp);
2433 }
2434
2435 static __net_initdata struct pernet_operations ipv4_inetpeer_ops = {
2436         .init   =       ipv4_inetpeer_init,
2437         .exit   =       ipv4_inetpeer_exit,
2438 };
2439
2440 #ifdef CONFIG_IP_ROUTE_CLASSID
2441 struct ip_rt_acct __percpu *ip_rt_acct __read_mostly;
2442 #endif /* CONFIG_IP_ROUTE_CLASSID */
2443
2444 int __init ip_rt_init(void)
2445 {
2446         int rc = 0;
2447
2448 #ifdef CONFIG_IP_ROUTE_CLASSID
2449         ip_rt_acct = __alloc_percpu(256 * sizeof(struct ip_rt_acct), __alignof__(struct ip_rt_acct));
2450         if (!ip_rt_acct)
2451                 panic("IP: failed to allocate ip_rt_acct\n");
2452 #endif
2453
2454         ipv4_dst_ops.kmem_cachep =
2455                 kmem_cache_create("ip_dst_cache", sizeof(struct rtable), 0,
2456                                   SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
2457
2458         ipv4_dst_blackhole_ops.kmem_cachep = ipv4_dst_ops.kmem_cachep;
2459
2460         if (dst_entries_init(&ipv4_dst_ops) < 0)
2461                 panic("IP: failed to allocate ipv4_dst_ops counter\n");
2462
2463         if (dst_entries_init(&ipv4_dst_blackhole_ops) < 0)
2464                 panic("IP: failed to allocate ipv4_dst_blackhole_ops counter\n");
2465
2466         ipv4_dst_ops.gc_thresh = ~0;
2467         ip_rt_max_size = INT_MAX;
2468
2469         devinet_init();
2470         ip_fib_init();
2471
2472         if (ip_rt_proc_init())
2473                 pr_err("Unable to create route proc files\n");
2474 #ifdef CONFIG_XFRM
2475         xfrm_init();
2476         xfrm4_init(ip_rt_max_size);
2477 #endif
2478         rtnl_register(PF_INET, RTM_GETROUTE, inet_rtm_getroute, NULL, NULL);
2479
2480 #ifdef CONFIG_SYSCTL
2481         register_pernet_subsys(&sysctl_route_ops);
2482 #endif
2483         register_pernet_subsys(&rt_genid_ops);
2484         register_pernet_subsys(&ipv4_inetpeer_ops);
2485         return rc;
2486 }
2487
2488 #ifdef CONFIG_SYSCTL
2489 /*
2490  * We really need to sanitize the damn ipv4 init order, then all
2491  * this nonsense will go away.
2492  */
2493 void __init ip_static_sysctl_init(void)
2494 {
2495         register_net_sysctl(&init_net, "net/ipv4/route", ipv4_route_table);
2496 }
2497 #endif