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TOMOYO Linux Cross Reference
Linux/net/ipv4/route.c

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  1 /*
  2  * INET         An implementation of the TCP/IP protocol suite for the LINUX
  3  *              operating system.  INET is implemented using the  BSD Socket
  4  *              interface as the means of communication with the user level.
  5  *
  6  *              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 <linux/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/string.h>
 74 #include <linux/socket.h>
 75 #include <linux/sockios.h>
 76 #include <linux/errno.h>
 77 #include <linux/in.h>
 78 #include <linux/inet.h>
 79 #include <linux/netdevice.h>
 80 #include <linux/proc_fs.h>
 81 #include <linux/init.h>
 82 #include <linux/skbuff.h>
 83 #include <linux/inetdevice.h>
 84 #include <linux/igmp.h>
 85 #include <linux/pkt_sched.h>
 86 #include <linux/mroute.h>
 87 #include <linux/netfilter_ipv4.h>
 88 #include <linux/random.h>
 89 #include <linux/rcupdate.h>
 90 #include <linux/times.h>
 91 #include <linux/slab.h>
 92 #include <linux/jhash.h>
 93 #include <net/dst.h>
 94 #include <net/dst_metadata.h>
 95 #include <net/net_namespace.h>
 96 #include <net/protocol.h>
 97 #include <net/ip.h>
 98 #include <net/route.h>
 99 #include <net/inetpeer.h>
100 #include <net/sock.h>
101 #include <net/ip_fib.h>
102 #include <net/arp.h>
103 #include <net/tcp.h>
104 #include <net/icmp.h>
105 #include <net/xfrm.h>
106 #include <net/lwtunnel.h>
107 #include <net/netevent.h>
108 #include <net/rtnetlink.h>
109 #ifdef CONFIG_SYSCTL
110 #include <linux/sysctl.h>
111 #include <linux/kmemleak.h>
112 #endif
113 #include <net/secure_seq.h>
114 #include <net/ip_tunnels.h>
115 #include <net/l3mdev.h>
116 
117 #define RT_FL_TOS(oldflp4) \
118         ((oldflp4)->flowi4_tos & (IPTOS_RT_MASK | RTO_ONLINK))
119 
120 #define RT_GC_TIMEOUT (300*HZ)
121 
122 static int ip_rt_max_size;
123 static int ip_rt_redirect_number __read_mostly  = 9;
124 static int ip_rt_redirect_load __read_mostly    = HZ / 50;
125 static int ip_rt_redirect_silence __read_mostly = ((HZ / 50) << (9 + 1));
126 static int ip_rt_error_cost __read_mostly       = HZ;
127 static int ip_rt_error_burst __read_mostly      = 5 * HZ;
128 static int ip_rt_mtu_expires __read_mostly      = 10 * 60 * HZ;
129 static int ip_rt_min_pmtu __read_mostly         = 512 + 20 + 20;
130 static int ip_rt_min_advmss __read_mostly       = 256;
131 
132 static int ip_rt_gc_timeout __read_mostly       = RT_GC_TIMEOUT;
133 /*
134  *      Interface to generic destination cache.
135  */
136 
137 static struct dst_entry *ipv4_dst_check(struct dst_entry *dst, u32 cookie);
138 static unsigned int      ipv4_default_advmss(const struct dst_entry *dst);
139 static unsigned int      ipv4_mtu(const struct dst_entry *dst);
140 static struct dst_entry *ipv4_negative_advice(struct dst_entry *dst);
141 static void              ipv4_link_failure(struct sk_buff *skb);
142 static void              ip_rt_update_pmtu(struct dst_entry *dst, struct sock *sk,
143                                            struct sk_buff *skb, u32 mtu);
144 static void              ip_do_redirect(struct dst_entry *dst, struct sock *sk,
145                                         struct sk_buff *skb);
146 static void             ipv4_dst_destroy(struct dst_entry *dst);
147 
148 static u32 *ipv4_cow_metrics(struct dst_entry *dst, unsigned long old)
149 {
150         WARN_ON(1);
151         return NULL;
152 }
153 
154 static struct neighbour *ipv4_neigh_lookup(const struct dst_entry *dst,
155                                            struct sk_buff *skb,
156                                            const void *daddr);
157 static void ipv4_confirm_neigh(const struct dst_entry *dst, const void *daddr);
158 
159 static struct dst_ops ipv4_dst_ops = {
160         .family =               AF_INET,
161         .check =                ipv4_dst_check,
162         .default_advmss =       ipv4_default_advmss,
163         .mtu =                  ipv4_mtu,
164         .cow_metrics =          ipv4_cow_metrics,
165         .destroy =              ipv4_dst_destroy,
166         .negative_advice =      ipv4_negative_advice,
167         .link_failure =         ipv4_link_failure,
168         .update_pmtu =          ip_rt_update_pmtu,
169         .redirect =             ip_do_redirect,
170         .local_out =            __ip_local_out,
171         .neigh_lookup =         ipv4_neigh_lookup,
172         .confirm_neigh =        ipv4_confirm_neigh,
173 };
174 
175 #define ECN_OR_COST(class)      TC_PRIO_##class
176 
177 const __u8 ip_tos2prio[16] = {
178         TC_PRIO_BESTEFFORT,
179         ECN_OR_COST(BESTEFFORT),
180         TC_PRIO_BESTEFFORT,
181         ECN_OR_COST(BESTEFFORT),
182         TC_PRIO_BULK,
183         ECN_OR_COST(BULK),
184         TC_PRIO_BULK,
185         ECN_OR_COST(BULK),
186         TC_PRIO_INTERACTIVE,
187         ECN_OR_COST(INTERACTIVE),
188         TC_PRIO_INTERACTIVE,
189         ECN_OR_COST(INTERACTIVE),
190         TC_PRIO_INTERACTIVE_BULK,
191         ECN_OR_COST(INTERACTIVE_BULK),
192         TC_PRIO_INTERACTIVE_BULK,
193         ECN_OR_COST(INTERACTIVE_BULK)
194 };
195 EXPORT_SYMBOL(ip_tos2prio);
196 
197 static DEFINE_PER_CPU(struct rt_cache_stat, rt_cache_stat);
198 #define RT_CACHE_STAT_INC(field) raw_cpu_inc(rt_cache_stat.field)
199 
200 #ifdef CONFIG_PROC_FS
201 static void *rt_cache_seq_start(struct seq_file *seq, loff_t *pos)
202 {
203         if (*pos)
204                 return NULL;
205         return SEQ_START_TOKEN;
206 }
207 
208 static void *rt_cache_seq_next(struct seq_file *seq, void *v, loff_t *pos)
209 {
210         ++*pos;
211         return NULL;
212 }
213 
214 static void rt_cache_seq_stop(struct seq_file *seq, void *v)
215 {
216 }
217 
218 static int rt_cache_seq_show(struct seq_file *seq, void *v)
219 {
220         if (v == SEQ_START_TOKEN)
221                 seq_printf(seq, "%-127s\n",
222                            "Iface\tDestination\tGateway \tFlags\t\tRefCnt\tUse\t"
223                            "Metric\tSource\t\tMTU\tWindow\tIRTT\tTOS\tHHRef\t"
224                            "HHUptod\tSpecDst");
225         return 0;
226 }
227 
228 static const struct seq_operations rt_cache_seq_ops = {
229         .start  = rt_cache_seq_start,
230         .next   = rt_cache_seq_next,
231         .stop   = rt_cache_seq_stop,
232         .show   = rt_cache_seq_show,
233 };
234 
235 static int rt_cache_seq_open(struct inode *inode, struct file *file)
236 {
237         return seq_open(file, &rt_cache_seq_ops);
238 }
239 
240 static const struct file_operations rt_cache_seq_fops = {
241         .owner   = THIS_MODULE,
242         .open    = rt_cache_seq_open,
243         .read    = seq_read,
244         .llseek  = seq_lseek,
245         .release = seq_release,
246 };
247 
248 
249 static void *rt_cpu_seq_start(struct seq_file *seq, loff_t *pos)
250 {
251         int cpu;
252 
253         if (*pos == 0)
254                 return SEQ_START_TOKEN;
255 
256         for (cpu = *pos-1; cpu < nr_cpu_ids; ++cpu) {
257                 if (!cpu_possible(cpu))
258                         continue;
259                 *pos = cpu+1;
260                 return &per_cpu(rt_cache_stat, cpu);
261         }
262         return NULL;
263 }
264 
265 static void *rt_cpu_seq_next(struct seq_file *seq, void *v, loff_t *pos)
266 {
267         int cpu;
268 
269         for (cpu = *pos; cpu < nr_cpu_ids; ++cpu) {
270                 if (!cpu_possible(cpu))
271                         continue;
272                 *pos = cpu+1;
273                 return &per_cpu(rt_cache_stat, cpu);
274         }
275         return NULL;
276 
277 }
278 
279 static void rt_cpu_seq_stop(struct seq_file *seq, void *v)
280 {
281 
282 }
283 
284 static int rt_cpu_seq_show(struct seq_file *seq, void *v)
285 {
286         struct rt_cache_stat *st = v;
287 
288         if (v == SEQ_START_TOKEN) {
289                 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");
290                 return 0;
291         }
292 
293         seq_printf(seq,"%08x  %08x %08x %08x %08x %08x %08x %08x "
294                    " %08x %08x %08x %08x %08x %08x %08x %08x %08x \n",
295                    dst_entries_get_slow(&ipv4_dst_ops),
296                    0, /* st->in_hit */
297                    st->in_slow_tot,
298                    st->in_slow_mc,
299                    st->in_no_route,
300                    st->in_brd,
301                    st->in_martian_dst,
302                    st->in_martian_src,
303 
304                    0, /* st->out_hit */
305                    st->out_slow_tot,
306                    st->out_slow_mc,
307 
308                    0, /* st->gc_total */
309                    0, /* st->gc_ignored */
310                    0, /* st->gc_goal_miss */
311                    0, /* st->gc_dst_overflow */
312                    0, /* st->in_hlist_search */
313                    0  /* st->out_hlist_search */
314                 );
315         return 0;
316 }
317 
318 static const struct seq_operations rt_cpu_seq_ops = {
319         .start  = rt_cpu_seq_start,
320         .next   = rt_cpu_seq_next,
321         .stop   = rt_cpu_seq_stop,
322         .show   = rt_cpu_seq_show,
323 };
324 
325 
326 static int rt_cpu_seq_open(struct inode *inode, struct file *file)
327 {
328         return seq_open(file, &rt_cpu_seq_ops);
329 }
330 
331 static const struct file_operations rt_cpu_seq_fops = {
332         .owner   = THIS_MODULE,
333         .open    = rt_cpu_seq_open,
334         .read    = seq_read,
335         .llseek  = seq_lseek,
336         .release = seq_release,
337 };
338 
339 #ifdef CONFIG_IP_ROUTE_CLASSID
340 static int rt_acct_proc_show(struct seq_file *m, void *v)
341 {
342         struct ip_rt_acct *dst, *src;
343         unsigned int i, j;
344 
345         dst = kcalloc(256, sizeof(struct ip_rt_acct), GFP_KERNEL);
346         if (!dst)
347                 return -ENOMEM;
348 
349         for_each_possible_cpu(i) {
350                 src = (struct ip_rt_acct *)per_cpu_ptr(ip_rt_acct, i);
351                 for (j = 0; j < 256; j++) {
352                         dst[j].o_bytes   += src[j].o_bytes;
353                         dst[j].o_packets += src[j].o_packets;
354                         dst[j].i_bytes   += src[j].i_bytes;
355                         dst[j].i_packets += src[j].i_packets;
356                 }
357         }
358 
359         seq_write(m, dst, 256 * sizeof(struct ip_rt_acct));
360         kfree(dst);
361         return 0;
362 }
363 
364 static int rt_acct_proc_open(struct inode *inode, struct file *file)
365 {
366         return single_open(file, rt_acct_proc_show, NULL);
367 }
368 
369 static const struct file_operations rt_acct_proc_fops = {
370         .owner          = THIS_MODULE,
371         .open           = rt_acct_proc_open,
372         .read           = seq_read,
373         .llseek         = seq_lseek,
374         .release        = single_release,
375 };
376 #endif
377 
378 static int __net_init ip_rt_do_proc_init(struct net *net)
379 {
380         struct proc_dir_entry *pde;
381 
382         pde = proc_create("rt_cache", S_IRUGO, net->proc_net,
383                           &rt_cache_seq_fops);
384         if (!pde)
385                 goto err1;
386 
387         pde = proc_create("rt_cache", S_IRUGO,
388                           net->proc_net_stat, &rt_cpu_seq_fops);
389         if (!pde)
390                 goto err2;
391 
392 #ifdef CONFIG_IP_ROUTE_CLASSID
393         pde = proc_create("rt_acct", 0, net->proc_net, &rt_acct_proc_fops);
394         if (!pde)
395                 goto err3;
396 #endif
397         return 0;
398 
399 #ifdef CONFIG_IP_ROUTE_CLASSID
400 err3:
401         remove_proc_entry("rt_cache", net->proc_net_stat);
402 #endif
403 err2:
404         remove_proc_entry("rt_cache", net->proc_net);
405 err1:
406         return -ENOMEM;
407 }
408 
409 static void __net_exit ip_rt_do_proc_exit(struct net *net)
410 {
411         remove_proc_entry("rt_cache", net->proc_net_stat);
412         remove_proc_entry("rt_cache", net->proc_net);
413 #ifdef CONFIG_IP_ROUTE_CLASSID
414         remove_proc_entry("rt_acct", net->proc_net);
415 #endif
416 }
417 
418 static struct pernet_operations ip_rt_proc_ops __net_initdata =  {
419         .init = ip_rt_do_proc_init,
420         .exit = ip_rt_do_proc_exit,
421 };
422 
423 static int __init ip_rt_proc_init(void)
424 {
425         return register_pernet_subsys(&ip_rt_proc_ops);
426 }
427 
428 #else
429 static inline int ip_rt_proc_init(void)
430 {
431         return 0;
432 }
433 #endif /* CONFIG_PROC_FS */
434 
435 static inline bool rt_is_expired(const struct rtable *rth)
436 {
437         return rth->rt_genid != rt_genid_ipv4(dev_net(rth->dst.dev));
438 }
439 
440 void rt_cache_flush(struct net *net)
441 {
442         rt_genid_bump_ipv4(net);
443 }
444 
445 static struct neighbour *ipv4_neigh_lookup(const struct dst_entry *dst,
446                                            struct sk_buff *skb,
447                                            const void *daddr)
448 {
449         struct net_device *dev = dst->dev;
450         const __be32 *pkey = daddr;
451         const struct rtable *rt;
452         struct neighbour *n;
453 
454         rt = (const struct rtable *) dst;
455         if (rt->rt_gateway)
456                 pkey = (const __be32 *) &rt->rt_gateway;
457         else if (skb)
458                 pkey = &ip_hdr(skb)->daddr;
459 
460         n = __ipv4_neigh_lookup(dev, *(__force u32 *)pkey);
461         if (n)
462                 return n;
463         return neigh_create(&arp_tbl, pkey, dev);
464 }
465 
466 static void ipv4_confirm_neigh(const struct dst_entry *dst, const void *daddr)
467 {
468         struct net_device *dev = dst->dev;
469         const __be32 *pkey = daddr;
470         const struct rtable *rt;
471 
472         rt = (const struct rtable *)dst;
473         if (rt->rt_gateway)
474                 pkey = (const __be32 *)&rt->rt_gateway;
475         else if (!daddr ||
476                  (rt->rt_flags &
477                   (RTCF_MULTICAST | RTCF_BROADCAST | RTCF_LOCAL)))
478                 return;
479 
480         __ipv4_confirm_neigh(dev, *(__force u32 *)pkey);
481 }
482 
483 #define IP_IDENTS_SZ 2048u
484 
485 static atomic_t *ip_idents __read_mostly;
486 static u32 *ip_tstamps __read_mostly;
487 
488 /* In order to protect privacy, we add a perturbation to identifiers
489  * if one generator is seldom used. This makes hard for an attacker
490  * to infer how many packets were sent between two points in time.
491  */
492 u32 ip_idents_reserve(u32 hash, int segs)
493 {
494         u32 *p_tstamp = ip_tstamps + hash % IP_IDENTS_SZ;
495         atomic_t *p_id = ip_idents + hash % IP_IDENTS_SZ;
496         u32 old = ACCESS_ONCE(*p_tstamp);
497         u32 now = (u32)jiffies;
498         u32 new, delta = 0;
499 
500         if (old != now && cmpxchg(p_tstamp, old, now) == old)
501                 delta = prandom_u32_max(now - old);
502 
503         /* Do not use atomic_add_return() as it makes UBSAN unhappy */
504         do {
505                 old = (u32)atomic_read(p_id);
506                 new = old + delta + segs;
507         } while (atomic_cmpxchg(p_id, old, new) != old);
508 
509         return new - segs;
510 }
511 EXPORT_SYMBOL(ip_idents_reserve);
512 
513 void __ip_select_ident(struct net *net, struct iphdr *iph, int segs)
514 {
515         static u32 ip_idents_hashrnd __read_mostly;
516         u32 hash, id;
517 
518         net_get_random_once(&ip_idents_hashrnd, sizeof(ip_idents_hashrnd));
519 
520         hash = jhash_3words((__force u32)iph->daddr,
521                             (__force u32)iph->saddr,
522                             iph->protocol ^ net_hash_mix(net),
523                             ip_idents_hashrnd);
524         id = ip_idents_reserve(hash, segs);
525         iph->id = htons(id);
526 }
527 EXPORT_SYMBOL(__ip_select_ident);
528 
529 static void __build_flow_key(const struct net *net, struct flowi4 *fl4,
530                              const struct sock *sk,
531                              const struct iphdr *iph,
532                              int oif, u8 tos,
533                              u8 prot, u32 mark, int flow_flags)
534 {
535         if (sk) {
536                 const struct inet_sock *inet = inet_sk(sk);
537 
538                 oif = sk->sk_bound_dev_if;
539                 mark = sk->sk_mark;
540                 tos = RT_CONN_FLAGS(sk);
541                 prot = inet->hdrincl ? IPPROTO_RAW : sk->sk_protocol;
542         }
543         flowi4_init_output(fl4, oif, mark, tos,
544                            RT_SCOPE_UNIVERSE, prot,
545                            flow_flags,
546                            iph->daddr, iph->saddr, 0, 0,
547                            sock_net_uid(net, sk));
548 }
549 
550 static void build_skb_flow_key(struct flowi4 *fl4, const struct sk_buff *skb,
551                                const struct sock *sk)
552 {
553         const struct net *net = dev_net(skb->dev);
554         const struct iphdr *iph = ip_hdr(skb);
555         int oif = skb->dev->ifindex;
556         u8 tos = RT_TOS(iph->tos);
557         u8 prot = iph->protocol;
558         u32 mark = skb->mark;
559 
560         __build_flow_key(net, fl4, sk, iph, oif, tos, prot, mark, 0);
561 }
562 
563 static void build_sk_flow_key(struct flowi4 *fl4, const struct sock *sk)
564 {
565         const struct inet_sock *inet = inet_sk(sk);
566         const struct ip_options_rcu *inet_opt;
567         __be32 daddr = inet->inet_daddr;
568 
569         rcu_read_lock();
570         inet_opt = rcu_dereference(inet->inet_opt);
571         if (inet_opt && inet_opt->opt.srr)
572                 daddr = inet_opt->opt.faddr;
573         flowi4_init_output(fl4, sk->sk_bound_dev_if, sk->sk_mark,
574                            RT_CONN_FLAGS(sk), RT_SCOPE_UNIVERSE,
575                            inet->hdrincl ? IPPROTO_RAW : sk->sk_protocol,
576                            inet_sk_flowi_flags(sk),
577                            daddr, inet->inet_saddr, 0, 0, sk->sk_uid);
578         rcu_read_unlock();
579 }
580 
581 static void ip_rt_build_flow_key(struct flowi4 *fl4, const struct sock *sk,
582                                  const struct sk_buff *skb)
583 {
584         if (skb)
585                 build_skb_flow_key(fl4, skb, sk);
586         else
587                 build_sk_flow_key(fl4, sk);
588 }
589 
590 static inline void rt_free(struct rtable *rt)
591 {
592         call_rcu(&rt->dst.rcu_head, dst_rcu_free);
593 }
594 
595 static DEFINE_SPINLOCK(fnhe_lock);
596 
597 static void fnhe_flush_routes(struct fib_nh_exception *fnhe)
598 {
599         struct rtable *rt;
600 
601         rt = rcu_dereference(fnhe->fnhe_rth_input);
602         if (rt) {
603                 RCU_INIT_POINTER(fnhe->fnhe_rth_input, NULL);
604                 rt_free(rt);
605         }
606         rt = rcu_dereference(fnhe->fnhe_rth_output);
607         if (rt) {
608                 RCU_INIT_POINTER(fnhe->fnhe_rth_output, NULL);
609                 rt_free(rt);
610         }
611 }
612 
613 static struct fib_nh_exception *fnhe_oldest(struct fnhe_hash_bucket *hash)
614 {
615         struct fib_nh_exception *fnhe, *oldest;
616 
617         oldest = rcu_dereference(hash->chain);
618         for (fnhe = rcu_dereference(oldest->fnhe_next); fnhe;
619              fnhe = rcu_dereference(fnhe->fnhe_next)) {
620                 if (time_before(fnhe->fnhe_stamp, oldest->fnhe_stamp))
621                         oldest = fnhe;
622         }
623         fnhe_flush_routes(oldest);
624         return oldest;
625 }
626 
627 static inline u32 fnhe_hashfun(__be32 daddr)
628 {
629         static u32 fnhe_hashrnd __read_mostly;
630         u32 hval;
631 
632         net_get_random_once(&fnhe_hashrnd, sizeof(fnhe_hashrnd));
633         hval = jhash_1word((__force u32) daddr, fnhe_hashrnd);
634         return hash_32(hval, FNHE_HASH_SHIFT);
635 }
636 
637 static void fill_route_from_fnhe(struct rtable *rt, struct fib_nh_exception *fnhe)
638 {
639         rt->rt_pmtu = fnhe->fnhe_pmtu;
640         rt->dst.expires = fnhe->fnhe_expires;
641 
642         if (fnhe->fnhe_gw) {
643                 rt->rt_flags |= RTCF_REDIRECTED;
644                 rt->rt_gateway = fnhe->fnhe_gw;
645                 rt->rt_uses_gateway = 1;
646         }
647 }
648 
649 static void update_or_create_fnhe(struct fib_nh *nh, __be32 daddr, __be32 gw,
650                                   u32 pmtu, unsigned long expires)
651 {
652         struct fnhe_hash_bucket *hash;
653         struct fib_nh_exception *fnhe;
654         struct rtable *rt;
655         unsigned int i;
656         int depth;
657         u32 hval = fnhe_hashfun(daddr);
658 
659         spin_lock_bh(&fnhe_lock);
660 
661         hash = rcu_dereference(nh->nh_exceptions);
662         if (!hash) {
663                 hash = kzalloc(FNHE_HASH_SIZE * sizeof(*hash), GFP_ATOMIC);
664                 if (!hash)
665                         goto out_unlock;
666                 rcu_assign_pointer(nh->nh_exceptions, hash);
667         }
668 
669         hash += hval;
670 
671         depth = 0;
672         for (fnhe = rcu_dereference(hash->chain); fnhe;
673              fnhe = rcu_dereference(fnhe->fnhe_next)) {
674                 if (fnhe->fnhe_daddr == daddr)
675                         break;
676                 depth++;
677         }
678 
679         if (fnhe) {
680                 if (gw)
681                         fnhe->fnhe_gw = gw;
682                 if (pmtu) {
683                         fnhe->fnhe_pmtu = pmtu;
684                         fnhe->fnhe_expires = max(1UL, expires);
685                 }
686                 /* Update all cached dsts too */
687                 rt = rcu_dereference(fnhe->fnhe_rth_input);
688                 if (rt)
689                         fill_route_from_fnhe(rt, fnhe);
690                 rt = rcu_dereference(fnhe->fnhe_rth_output);
691                 if (rt)
692                         fill_route_from_fnhe(rt, fnhe);
693         } else {
694                 if (depth > FNHE_RECLAIM_DEPTH)
695                         fnhe = fnhe_oldest(hash);
696                 else {
697                         fnhe = kzalloc(sizeof(*fnhe), GFP_ATOMIC);
698                         if (!fnhe)
699                                 goto out_unlock;
700 
701                         fnhe->fnhe_next = hash->chain;
702                         rcu_assign_pointer(hash->chain, fnhe);
703                 }
704                 fnhe->fnhe_genid = fnhe_genid(dev_net(nh->nh_dev));
705                 fnhe->fnhe_daddr = daddr;
706                 fnhe->fnhe_gw = gw;
707                 fnhe->fnhe_pmtu = pmtu;
708                 fnhe->fnhe_expires = expires;
709 
710                 /* Exception created; mark the cached routes for the nexthop
711                  * stale, so anyone caching it rechecks if this exception
712                  * applies to them.
713                  */
714                 rt = rcu_dereference(nh->nh_rth_input);
715                 if (rt)
716                         rt->dst.obsolete = DST_OBSOLETE_KILL;
717 
718                 for_each_possible_cpu(i) {
719                         struct rtable __rcu **prt;
720                         prt = per_cpu_ptr(nh->nh_pcpu_rth_output, i);
721                         rt = rcu_dereference(*prt);
722                         if (rt)
723                                 rt->dst.obsolete = DST_OBSOLETE_KILL;
724                 }
725         }
726 
727         fnhe->fnhe_stamp = jiffies;
728 
729 out_unlock:
730         spin_unlock_bh(&fnhe_lock);
731 }
732 
733 static void __ip_do_redirect(struct rtable *rt, struct sk_buff *skb, struct flowi4 *fl4,
734                              bool kill_route)
735 {
736         __be32 new_gw = icmp_hdr(skb)->un.gateway;
737         __be32 old_gw = ip_hdr(skb)->saddr;
738         struct net_device *dev = skb->dev;
739         struct in_device *in_dev;
740         struct fib_result res;
741         struct neighbour *n;
742         struct net *net;
743 
744         switch (icmp_hdr(skb)->code & 7) {
745         case ICMP_REDIR_NET:
746         case ICMP_REDIR_NETTOS:
747         case ICMP_REDIR_HOST:
748         case ICMP_REDIR_HOSTTOS:
749                 break;
750 
751         default:
752                 return;
753         }
754 
755         if (rt->rt_gateway != old_gw)
756                 return;
757 
758         in_dev = __in_dev_get_rcu(dev);
759         if (!in_dev)
760                 return;
761 
762         net = dev_net(dev);
763         if (new_gw == old_gw || !IN_DEV_RX_REDIRECTS(in_dev) ||
764             ipv4_is_multicast(new_gw) || ipv4_is_lbcast(new_gw) ||
765             ipv4_is_zeronet(new_gw))
766                 goto reject_redirect;
767 
768         if (!IN_DEV_SHARED_MEDIA(in_dev)) {
769                 if (!inet_addr_onlink(in_dev, new_gw, old_gw))
770                         goto reject_redirect;
771                 if (IN_DEV_SEC_REDIRECTS(in_dev) && ip_fib_check_default(new_gw, dev))
772                         goto reject_redirect;
773         } else {
774                 if (inet_addr_type(net, new_gw) != RTN_UNICAST)
775                         goto reject_redirect;
776         }
777 
778         n = __ipv4_neigh_lookup(rt->dst.dev, new_gw);
779         if (!n)
780                 n = neigh_create(&arp_tbl, &new_gw, rt->dst.dev);
781         if (!IS_ERR(n)) {
782                 if (!(n->nud_state & NUD_VALID)) {
783                         neigh_event_send(n, NULL);
784                 } else {
785                         if (fib_lookup(net, fl4, &res, 0) == 0) {
786                                 struct fib_nh *nh = &FIB_RES_NH(res);
787 
788                                 update_or_create_fnhe(nh, fl4->daddr, new_gw,
789                                                 0, jiffies + ip_rt_gc_timeout);
790                         }
791                         if (kill_route)
792                                 rt->dst.obsolete = DST_OBSOLETE_KILL;
793                         call_netevent_notifiers(NETEVENT_NEIGH_UPDATE, n);
794                 }
795                 neigh_release(n);
796         }
797         return;
798 
799 reject_redirect:
800 #ifdef CONFIG_IP_ROUTE_VERBOSE
801         if (IN_DEV_LOG_MARTIANS(in_dev)) {
802                 const struct iphdr *iph = (const struct iphdr *) skb->data;
803                 __be32 daddr = iph->daddr;
804                 __be32 saddr = iph->saddr;
805 
806                 net_info_ratelimited("Redirect from %pI4 on %s about %pI4 ignored\n"
807                                      "  Advised path = %pI4 -> %pI4\n",
808                                      &old_gw, dev->name, &new_gw,
809                                      &saddr, &daddr);
810         }
811 #endif
812         ;
813 }
814 
815 static void ip_do_redirect(struct dst_entry *dst, struct sock *sk, struct sk_buff *skb)
816 {
817         struct rtable *rt;
818         struct flowi4 fl4;
819         const struct iphdr *iph = (const struct iphdr *) skb->data;
820         struct net *net = dev_net(skb->dev);
821         int oif = skb->dev->ifindex;
822         u8 tos = RT_TOS(iph->tos);
823         u8 prot = iph->protocol;
824         u32 mark = skb->mark;
825 
826         rt = (struct rtable *) dst;
827 
828         __build_flow_key(net, &fl4, sk, iph, oif, tos, prot, mark, 0);
829         __ip_do_redirect(rt, skb, &fl4, true);
830 }
831 
832 static struct dst_entry *ipv4_negative_advice(struct dst_entry *dst)
833 {
834         struct rtable *rt = (struct rtable *)dst;
835         struct dst_entry *ret = dst;
836 
837         if (rt) {
838                 if (dst->obsolete > 0) {
839                         ip_rt_put(rt);
840                         ret = NULL;
841                 } else if ((rt->rt_flags & RTCF_REDIRECTED) ||
842                            rt->dst.expires) {
843                         ip_rt_put(rt);
844                         ret = NULL;
845                 }
846         }
847         return ret;
848 }
849 
850 /*
851  * Algorithm:
852  *      1. The first ip_rt_redirect_number redirects are sent
853  *         with exponential backoff, then we stop sending them at all,
854  *         assuming that the host ignores our redirects.
855  *      2. If we did not see packets requiring redirects
856  *         during ip_rt_redirect_silence, we assume that the host
857  *         forgot redirected route and start to send redirects again.
858  *
859  * This algorithm is much cheaper and more intelligent than dumb load limiting
860  * in icmp.c.
861  *
862  * NOTE. Do not forget to inhibit load limiting for redirects (redundant)
863  * and "frag. need" (breaks PMTU discovery) in icmp.c.
864  */
865 
866 void ip_rt_send_redirect(struct sk_buff *skb)
867 {
868         struct rtable *rt = skb_rtable(skb);
869         struct in_device *in_dev;
870         struct inet_peer *peer;
871         struct net *net;
872         int log_martians;
873         int vif;
874 
875         rcu_read_lock();
876         in_dev = __in_dev_get_rcu(rt->dst.dev);
877         if (!in_dev || !IN_DEV_TX_REDIRECTS(in_dev)) {
878                 rcu_read_unlock();
879                 return;
880         }
881         log_martians = IN_DEV_LOG_MARTIANS(in_dev);
882         vif = l3mdev_master_ifindex_rcu(rt->dst.dev);
883         rcu_read_unlock();
884 
885         net = dev_net(rt->dst.dev);
886         peer = inet_getpeer_v4(net->ipv4.peers, ip_hdr(skb)->saddr, vif, 1);
887         if (!peer) {
888                 icmp_send(skb, ICMP_REDIRECT, ICMP_REDIR_HOST,
889                           rt_nexthop(rt, ip_hdr(skb)->daddr));
890                 return;
891         }
892 
893         /* No redirected packets during ip_rt_redirect_silence;
894          * reset the algorithm.
895          */
896         if (time_after(jiffies, peer->rate_last + ip_rt_redirect_silence))
897                 peer->rate_tokens = 0;
898 
899         /* Too many ignored redirects; do not send anything
900          * set dst.rate_last to the last seen redirected packet.
901          */
902         if (peer->rate_tokens >= ip_rt_redirect_number) {
903                 peer->rate_last = jiffies;
904                 goto out_put_peer;
905         }
906 
907         /* Check for load limit; set rate_last to the latest sent
908          * redirect.
909          */
910         if (peer->rate_tokens == 0 ||
911             time_after(jiffies,
912                        (peer->rate_last +
913                         (ip_rt_redirect_load << peer->rate_tokens)))) {
914                 __be32 gw = rt_nexthop(rt, ip_hdr(skb)->daddr);
915 
916                 icmp_send(skb, ICMP_REDIRECT, ICMP_REDIR_HOST, gw);
917                 peer->rate_last = jiffies;
918                 ++peer->rate_tokens;
919 #ifdef CONFIG_IP_ROUTE_VERBOSE
920                 if (log_martians &&
921                     peer->rate_tokens == ip_rt_redirect_number)
922                         net_warn_ratelimited("host %pI4/if%d ignores redirects for %pI4 to %pI4\n",
923                                              &ip_hdr(skb)->saddr, inet_iif(skb),
924                                              &ip_hdr(skb)->daddr, &gw);
925 #endif
926         }
927 out_put_peer:
928         inet_putpeer(peer);
929 }
930 
931 static int ip_error(struct sk_buff *skb)
932 {
933         struct in_device *in_dev = __in_dev_get_rcu(skb->dev);
934         struct rtable *rt = skb_rtable(skb);
935         struct inet_peer *peer;
936         unsigned long now;
937         struct net *net;
938         bool send;
939         int code;
940 
941         /* IP on this device is disabled. */
942         if (!in_dev)
943                 goto out;
944 
945         net = dev_net(rt->dst.dev);
946         if (!IN_DEV_FORWARD(in_dev)) {
947                 switch (rt->dst.error) {
948                 case EHOSTUNREACH:
949                         __IP_INC_STATS(net, IPSTATS_MIB_INADDRERRORS);
950                         break;
951 
952                 case ENETUNREACH:
953                         __IP_INC_STATS(net, IPSTATS_MIB_INNOROUTES);
954                         break;
955                 }
956                 goto out;
957         }
958 
959         switch (rt->dst.error) {
960         case EINVAL:
961         default:
962                 goto out;
963         case EHOSTUNREACH:
964                 code = ICMP_HOST_UNREACH;
965                 break;
966         case ENETUNREACH:
967                 code = ICMP_NET_UNREACH;
968                 __IP_INC_STATS(net, IPSTATS_MIB_INNOROUTES);
969                 break;
970         case EACCES:
971                 code = ICMP_PKT_FILTERED;
972                 break;
973         }
974 
975         peer = inet_getpeer_v4(net->ipv4.peers, ip_hdr(skb)->saddr,
976                                l3mdev_master_ifindex(skb->dev), 1);
977 
978         send = true;
979         if (peer) {
980                 now = jiffies;
981                 peer->rate_tokens += now - peer->rate_last;
982                 if (peer->rate_tokens > ip_rt_error_burst)
983                         peer->rate_tokens = ip_rt_error_burst;
984                 peer->rate_last = now;
985                 if (peer->rate_tokens >= ip_rt_error_cost)
986                         peer->rate_tokens -= ip_rt_error_cost;
987                 else
988                         send = false;
989                 inet_putpeer(peer);
990         }
991         if (send)
992                 icmp_send(skb, ICMP_DEST_UNREACH, code, 0);
993 
994 out:    kfree_skb(skb);
995         return 0;
996 }
997 
998 static void __ip_rt_update_pmtu(struct rtable *rt, struct flowi4 *fl4, u32 mtu)
999 {
1000         struct dst_entry *dst = &rt->dst;
1001         struct fib_result res;
1002 
1003         if (dst_metric_locked(dst, RTAX_MTU))
1004                 return;
1005 
1006         if (ipv4_mtu(dst) < mtu)
1007                 return;
1008 
1009         if (mtu < ip_rt_min_pmtu)
1010                 mtu = ip_rt_min_pmtu;
1011 
1012         if (rt->rt_pmtu == mtu &&
1013             time_before(jiffies, dst->expires - ip_rt_mtu_expires / 2))
1014                 return;
1015 
1016         rcu_read_lock();
1017         if (fib_lookup(dev_net(dst->dev), fl4, &res, 0) == 0) {
1018                 struct fib_nh *nh = &FIB_RES_NH(res);
1019 
1020                 update_or_create_fnhe(nh, fl4->daddr, 0, mtu,
1021                                       jiffies + ip_rt_mtu_expires);
1022         }
1023         rcu_read_unlock();
1024 }
1025 
1026 static void ip_rt_update_pmtu(struct dst_entry *dst, struct sock *sk,
1027                               struct sk_buff *skb, u32 mtu)
1028 {
1029         struct rtable *rt = (struct rtable *) dst;
1030         struct flowi4 fl4;
1031 
1032         ip_rt_build_flow_key(&fl4, sk, skb);
1033         __ip_rt_update_pmtu(rt, &fl4, mtu);
1034 }
1035 
1036 void ipv4_update_pmtu(struct sk_buff *skb, struct net *net, u32 mtu,
1037                       int oif, u32 mark, u8 protocol, int flow_flags)
1038 {
1039         const struct iphdr *iph = (const struct iphdr *) skb->data;
1040         struct flowi4 fl4;
1041         struct rtable *rt;
1042 
1043         if (!mark)
1044                 mark = IP4_REPLY_MARK(net, skb->mark);
1045 
1046         __build_flow_key(net, &fl4, NULL, iph, oif,
1047                          RT_TOS(iph->tos), protocol, mark, flow_flags);
1048         rt = __ip_route_output_key(net, &fl4);
1049         if (!IS_ERR(rt)) {
1050                 __ip_rt_update_pmtu(rt, &fl4, mtu);
1051                 ip_rt_put(rt);
1052         }
1053 }
1054 EXPORT_SYMBOL_GPL(ipv4_update_pmtu);
1055 
1056 static void __ipv4_sk_update_pmtu(struct sk_buff *skb, struct sock *sk, u32 mtu)
1057 {
1058         const struct iphdr *iph = (const struct iphdr *) skb->data;
1059         struct flowi4 fl4;
1060         struct rtable *rt;
1061 
1062         __build_flow_key(sock_net(sk), &fl4, sk, iph, 0, 0, 0, 0, 0);
1063 
1064         if (!fl4.flowi4_mark)
1065                 fl4.flowi4_mark = IP4_REPLY_MARK(sock_net(sk), skb->mark);
1066 
1067         rt = __ip_route_output_key(sock_net(sk), &fl4);
1068         if (!IS_ERR(rt)) {
1069                 __ip_rt_update_pmtu(rt, &fl4, mtu);
1070                 ip_rt_put(rt);
1071         }
1072 }
1073 
1074 void ipv4_sk_update_pmtu(struct sk_buff *skb, struct sock *sk, u32 mtu)
1075 {
1076         const struct iphdr *iph = (const struct iphdr *) skb->data;
1077         struct flowi4 fl4;
1078         struct rtable *rt;
1079         struct dst_entry *odst = NULL;
1080         bool new = false;
1081         struct net *net = sock_net(sk);
1082 
1083         bh_lock_sock(sk);
1084 
1085         if (!ip_sk_accept_pmtu(sk))
1086                 goto out;
1087 
1088         odst = sk_dst_get(sk);
1089 
1090         if (sock_owned_by_user(sk) || !odst) {
1091                 __ipv4_sk_update_pmtu(skb, sk, mtu);
1092                 goto out;
1093         }
1094 
1095         __build_flow_key(net, &fl4, sk, iph, 0, 0, 0, 0, 0);
1096 
1097         rt = (struct rtable *)odst;
1098         if (odst->obsolete && !odst->ops->check(odst, 0)) {
1099                 rt = ip_route_output_flow(sock_net(sk), &fl4, sk);
1100                 if (IS_ERR(rt))
1101                         goto out;
1102 
1103                 new = true;
1104         }
1105 
1106         __ip_rt_update_pmtu((struct rtable *) rt->dst.path, &fl4, mtu);
1107 
1108         if (!dst_check(&rt->dst, 0)) {
1109                 if (new)
1110                         dst_release(&rt->dst);
1111 
1112                 rt = ip_route_output_flow(sock_net(sk), &fl4, sk);
1113                 if (IS_ERR(rt))
1114                         goto out;
1115 
1116                 new = true;
1117         }
1118 
1119         if (new)
1120                 sk_dst_set(sk, &rt->dst);
1121 
1122 out:
1123         bh_unlock_sock(sk);
1124         dst_release(odst);
1125 }
1126 EXPORT_SYMBOL_GPL(ipv4_sk_update_pmtu);
1127 
1128 void ipv4_redirect(struct sk_buff *skb, struct net *net,
1129                    int oif, u32 mark, u8 protocol, int flow_flags)
1130 {
1131         const struct iphdr *iph = (const struct iphdr *) skb->data;
1132         struct flowi4 fl4;
1133         struct rtable *rt;
1134 
1135         __build_flow_key(net, &fl4, NULL, iph, oif,
1136                          RT_TOS(iph->tos), protocol, mark, flow_flags);
1137         rt = __ip_route_output_key(net, &fl4);
1138         if (!IS_ERR(rt)) {
1139                 __ip_do_redirect(rt, skb, &fl4, false);
1140                 ip_rt_put(rt);
1141         }
1142 }
1143 EXPORT_SYMBOL_GPL(ipv4_redirect);
1144 
1145 void ipv4_sk_redirect(struct sk_buff *skb, struct sock *sk)
1146 {
1147         const struct iphdr *iph = (const struct iphdr *) skb->data;
1148         struct flowi4 fl4;
1149         struct rtable *rt;
1150         struct net *net = sock_net(sk);
1151 
1152         __build_flow_key(net, &fl4, sk, iph, 0, 0, 0, 0, 0);
1153         rt = __ip_route_output_key(net, &fl4);
1154         if (!IS_ERR(rt)) {
1155                 __ip_do_redirect(rt, skb, &fl4, false);
1156                 ip_rt_put(rt);
1157         }
1158 }
1159 EXPORT_SYMBOL_GPL(ipv4_sk_redirect);
1160 
1161 static struct dst_entry *ipv4_dst_check(struct dst_entry *dst, u32 cookie)
1162 {
1163         struct rtable *rt = (struct rtable *) dst;
1164 
1165         /* All IPV4 dsts are created with ->obsolete set to the value
1166          * DST_OBSOLETE_FORCE_CHK which forces validation calls down
1167          * into this function always.
1168          *
1169          * When a PMTU/redirect information update invalidates a route,
1170          * this is indicated by setting obsolete to DST_OBSOLETE_KILL or
1171          * DST_OBSOLETE_DEAD by dst_free().
1172          */
1173         if (dst->obsolete != DST_OBSOLETE_FORCE_CHK || rt_is_expired(rt))
1174                 return NULL;
1175         return dst;
1176 }
1177 
1178 static void ipv4_link_failure(struct sk_buff *skb)
1179 {
1180         struct rtable *rt;
1181 
1182         icmp_send(skb, ICMP_DEST_UNREACH, ICMP_HOST_UNREACH, 0);
1183 
1184         rt = skb_rtable(skb);
1185         if (rt)
1186                 dst_set_expires(&rt->dst, 0);
1187 }
1188 
1189 static int ip_rt_bug(struct net *net, struct sock *sk, struct sk_buff *skb)
1190 {
1191         pr_debug("%s: %pI4 -> %pI4, %s\n",
1192                  __func__, &ip_hdr(skb)->saddr, &ip_hdr(skb)->daddr,
1193                  skb->dev ? skb->dev->name : "?");
1194         kfree_skb(skb);
1195         WARN_ON(1);
1196         return 0;
1197 }
1198 
1199 /*
1200    We do not cache source address of outgoing interface,
1201    because it is used only by IP RR, TS and SRR options,
1202    so that it out of fast path.
1203 
1204    BTW remember: "addr" is allowed to be not aligned
1205    in IP options!
1206  */
1207 
1208 void ip_rt_get_source(u8 *addr, struct sk_buff *skb, struct rtable *rt)
1209 {
1210         __be32 src;
1211 
1212         if (rt_is_output_route(rt))
1213                 src = ip_hdr(skb)->saddr;
1214         else {
1215                 struct fib_result res;
1216                 struct flowi4 fl4;
1217                 struct iphdr *iph;
1218 
1219                 iph = ip_hdr(skb);
1220 
1221                 memset(&fl4, 0, sizeof(fl4));
1222                 fl4.daddr = iph->daddr;
1223                 fl4.saddr = iph->saddr;
1224                 fl4.flowi4_tos = RT_TOS(iph->tos);
1225                 fl4.flowi4_oif = rt->dst.dev->ifindex;
1226                 fl4.flowi4_iif = skb->dev->ifindex;
1227                 fl4.flowi4_mark = skb->mark;
1228 
1229                 rcu_read_lock();
1230                 if (fib_lookup(dev_net(rt->dst.dev), &fl4, &res, 0) == 0)
1231                         src = FIB_RES_PREFSRC(dev_net(rt->dst.dev), res);
1232                 else
1233                         src = inet_select_addr(rt->dst.dev,
1234                                                rt_nexthop(rt, iph->daddr),
1235                                                RT_SCOPE_UNIVERSE);
1236                 rcu_read_unlock();
1237         }
1238         memcpy(addr, &src, 4);
1239 }
1240 
1241 #ifdef CONFIG_IP_ROUTE_CLASSID
1242 static void set_class_tag(struct rtable *rt, u32 tag)
1243 {
1244         if (!(rt->dst.tclassid & 0xFFFF))
1245                 rt->dst.tclassid |= tag & 0xFFFF;
1246         if (!(rt->dst.tclassid & 0xFFFF0000))
1247                 rt->dst.tclassid |= tag & 0xFFFF0000;
1248 }
1249 #endif
1250 
1251 static unsigned int ipv4_default_advmss(const struct dst_entry *dst)
1252 {
1253         unsigned int advmss = dst_metric_raw(dst, RTAX_ADVMSS);
1254 
1255         if (advmss == 0) {
1256                 advmss = max_t(unsigned int, dst->dev->mtu - 40,
1257                                ip_rt_min_advmss);
1258                 if (advmss > 65535 - 40)
1259                         advmss = 65535 - 40;
1260         }
1261         return advmss;
1262 }
1263 
1264 static unsigned int ipv4_mtu(const struct dst_entry *dst)
1265 {
1266         const struct rtable *rt = (const struct rtable *) dst;
1267         unsigned int mtu = rt->rt_pmtu;
1268 
1269         if (!mtu || time_after_eq(jiffies, rt->dst.expires))
1270                 mtu = dst_metric_raw(dst, RTAX_MTU);
1271 
1272         if (mtu)
1273                 return mtu;
1274 
1275         mtu = dst->dev->mtu;
1276 
1277         if (unlikely(dst_metric_locked(dst, RTAX_MTU))) {
1278                 if (rt->rt_uses_gateway && mtu > 576)
1279                         mtu = 576;
1280         }
1281 
1282         mtu = min_t(unsigned int, mtu, IP_MAX_MTU);
1283 
1284         return mtu - lwtunnel_headroom(dst->lwtstate, mtu);
1285 }
1286 
1287 static struct fib_nh_exception *find_exception(struct fib_nh *nh, __be32 daddr)
1288 {
1289         struct fnhe_hash_bucket *hash = rcu_dereference(nh->nh_exceptions);
1290         struct fib_nh_exception *fnhe;
1291         u32 hval;
1292 
1293         if (!hash)
1294                 return NULL;
1295 
1296         hval = fnhe_hashfun(daddr);
1297 
1298         for (fnhe = rcu_dereference(hash[hval].chain); fnhe;
1299              fnhe = rcu_dereference(fnhe->fnhe_next)) {
1300                 if (fnhe->fnhe_daddr == daddr)
1301                         return fnhe;
1302         }
1303         return NULL;
1304 }
1305 
1306 static bool rt_bind_exception(struct rtable *rt, struct fib_nh_exception *fnhe,
1307                               __be32 daddr)
1308 {
1309         bool ret = false;
1310 
1311         spin_lock_bh(&fnhe_lock);
1312 
1313         if (daddr == fnhe->fnhe_daddr) {
1314                 struct rtable __rcu **porig;
1315                 struct rtable *orig;
1316                 int genid = fnhe_genid(dev_net(rt->dst.dev));
1317 
1318                 if (rt_is_input_route(rt))
1319                         porig = &fnhe->fnhe_rth_input;
1320                 else
1321                         porig = &fnhe->fnhe_rth_output;
1322                 orig = rcu_dereference(*porig);
1323 
1324                 if (fnhe->fnhe_genid != genid) {
1325                         fnhe->fnhe_genid = genid;
1326                         fnhe->fnhe_gw = 0;
1327                         fnhe->fnhe_pmtu = 0;
1328                         fnhe->fnhe_expires = 0;
1329                         fnhe_flush_routes(fnhe);
1330                         orig = NULL;
1331                 }
1332                 fill_route_from_fnhe(rt, fnhe);
1333                 if (!rt->rt_gateway)
1334                         rt->rt_gateway = daddr;
1335 
1336                 if (!(rt->dst.flags & DST_NOCACHE)) {
1337                         rcu_assign_pointer(*porig, rt);
1338                         if (orig)
1339                                 rt_free(orig);
1340                         ret = true;
1341                 }
1342 
1343                 fnhe->fnhe_stamp = jiffies;
1344         }
1345         spin_unlock_bh(&fnhe_lock);
1346 
1347         return ret;
1348 }
1349 
1350 static bool rt_cache_route(struct fib_nh *nh, struct rtable *rt)
1351 {
1352         struct rtable *orig, *prev, **p;
1353         bool ret = true;
1354 
1355         if (rt_is_input_route(rt)) {
1356                 p = (struct rtable **)&nh->nh_rth_input;
1357         } else {
1358                 p = (struct rtable **)raw_cpu_ptr(nh->nh_pcpu_rth_output);
1359         }
1360         orig = *p;
1361 
1362         prev = cmpxchg(p, orig, rt);
1363         if (prev == orig) {
1364                 if (orig)
1365                         rt_free(orig);
1366         } else
1367                 ret = false;
1368 
1369         return ret;
1370 }
1371 
1372 struct uncached_list {
1373         spinlock_t              lock;
1374         struct list_head        head;
1375 };
1376 
1377 static DEFINE_PER_CPU_ALIGNED(struct uncached_list, rt_uncached_list);
1378 
1379 static void rt_add_uncached_list(struct rtable *rt)
1380 {
1381         struct uncached_list *ul = raw_cpu_ptr(&rt_uncached_list);
1382 
1383         rt->rt_uncached_list = ul;
1384 
1385         spin_lock_bh(&ul->lock);
1386         list_add_tail(&rt->rt_uncached, &ul->head);
1387         spin_unlock_bh(&ul->lock);
1388 }
1389 
1390 static void ipv4_dst_destroy(struct dst_entry *dst)
1391 {
1392         struct dst_metrics *p = (struct dst_metrics *)DST_METRICS_PTR(dst);
1393         struct rtable *rt = (struct rtable *) dst;
1394 
1395         if (p != &dst_default_metrics && atomic_dec_and_test(&p->refcnt))
1396                 kfree(p);
1397 
1398         if (!list_empty(&rt->rt_uncached)) {
1399                 struct uncached_list *ul = rt->rt_uncached_list;
1400 
1401                 spin_lock_bh(&ul->lock);
1402                 list_del(&rt->rt_uncached);
1403                 spin_unlock_bh(&ul->lock);
1404         }
1405 }
1406 
1407 void rt_flush_dev(struct net_device *dev)
1408 {
1409         struct net *net = dev_net(dev);
1410         struct rtable *rt;
1411         int cpu;
1412 
1413         for_each_possible_cpu(cpu) {
1414                 struct uncached_list *ul = &per_cpu(rt_uncached_list, cpu);
1415 
1416                 spin_lock_bh(&ul->lock);
1417                 list_for_each_entry(rt, &ul->head, rt_uncached) {
1418                         if (rt->dst.dev != dev)
1419                                 continue;
1420                         rt->dst.dev = net->loopback_dev;
1421                         dev_hold(rt->dst.dev);
1422                         dev_put(dev);
1423                 }
1424                 spin_unlock_bh(&ul->lock);
1425         }
1426 }
1427 
1428 static bool rt_cache_valid(const struct rtable *rt)
1429 {
1430         return  rt &&
1431                 rt->dst.obsolete == DST_OBSOLETE_FORCE_CHK &&
1432                 !rt_is_expired(rt);
1433 }
1434 
1435 static void rt_set_nexthop(struct rtable *rt, __be32 daddr,
1436                            const struct fib_result *res,
1437                            struct fib_nh_exception *fnhe,
1438                            struct fib_info *fi, u16 type, u32 itag)
1439 {
1440         bool cached = false;
1441 
1442         if (fi) {
1443                 struct fib_nh *nh = &FIB_RES_NH(*res);
1444 
1445                 if (nh->nh_gw && nh->nh_scope == RT_SCOPE_LINK) {
1446                         rt->rt_gateway = nh->nh_gw;
1447                         rt->rt_uses_gateway = 1;
1448                 }
1449                 dst_init_metrics(&rt->dst, fi->fib_metrics->metrics, true);
1450                 if (fi->fib_metrics != &dst_default_metrics) {
1451                         rt->dst._metrics |= DST_METRICS_REFCOUNTED;
1452                         atomic_inc(&fi->fib_metrics->refcnt);
1453                 }
1454 #ifdef CONFIG_IP_ROUTE_CLASSID
1455                 rt->dst.tclassid = nh->nh_tclassid;
1456 #endif
1457                 rt->dst.lwtstate = lwtstate_get(nh->nh_lwtstate);
1458                 if (unlikely(fnhe))
1459                         cached = rt_bind_exception(rt, fnhe, daddr);
1460                 else if (!(rt->dst.flags & DST_NOCACHE))
1461                         cached = rt_cache_route(nh, rt);
1462                 if (unlikely(!cached)) {
1463                         /* Routes we intend to cache in nexthop exception or
1464                          * FIB nexthop have the DST_NOCACHE bit clear.
1465                          * However, if we are unsuccessful at storing this
1466                          * route into the cache we really need to set it.
1467                          */
1468                         rt->dst.flags |= DST_NOCACHE;
1469                         if (!rt->rt_gateway)
1470                                 rt->rt_gateway = daddr;
1471                         rt_add_uncached_list(rt);
1472                 }
1473         } else
1474                 rt_add_uncached_list(rt);
1475 
1476 #ifdef CONFIG_IP_ROUTE_CLASSID
1477 #ifdef CONFIG_IP_MULTIPLE_TABLES
1478         set_class_tag(rt, res->tclassid);
1479 #endif
1480         set_class_tag(rt, itag);
1481 #endif
1482 }
1483 
1484 struct rtable *rt_dst_alloc(struct net_device *dev,
1485                             unsigned int flags, u16 type,
1486                             bool nopolicy, bool noxfrm, bool will_cache)
1487 {
1488         struct rtable *rt;
1489 
1490         rt = dst_alloc(&ipv4_dst_ops, dev, 1, DST_OBSOLETE_FORCE_CHK,
1491                        (will_cache ? 0 : (DST_HOST | DST_NOCACHE)) |
1492                        (nopolicy ? DST_NOPOLICY : 0) |
1493                        (noxfrm ? DST_NOXFRM : 0));
1494 
1495         if (rt) {
1496                 rt->rt_genid = rt_genid_ipv4(dev_net(dev));
1497                 rt->rt_flags = flags;
1498                 rt->rt_type = type;
1499                 rt->rt_is_input = 0;
1500                 rt->rt_iif = 0;
1501                 rt->rt_pmtu = 0;
1502                 rt->rt_gateway = 0;
1503                 rt->rt_uses_gateway = 0;
1504                 rt->rt_table_id = 0;
1505                 INIT_LIST_HEAD(&rt->rt_uncached);
1506 
1507                 rt->dst.output = ip_output;
1508                 if (flags & RTCF_LOCAL)
1509                         rt->dst.input = ip_local_deliver;
1510         }
1511 
1512         return rt;
1513 }
1514 EXPORT_SYMBOL(rt_dst_alloc);
1515 
1516 /* called in rcu_read_lock() section */
1517 static int ip_route_input_mc(struct sk_buff *skb, __be32 daddr, __be32 saddr,
1518                                 u8 tos, struct net_device *dev, int our)
1519 {
1520         struct rtable *rth;
1521         struct in_device *in_dev = __in_dev_get_rcu(dev);
1522         unsigned int flags = RTCF_MULTICAST;
1523         u32 itag = 0;
1524         int err;
1525 
1526         /* Primary sanity checks. */
1527 
1528         if (!in_dev)
1529                 return -EINVAL;
1530 
1531         if (ipv4_is_multicast(saddr) || ipv4_is_lbcast(saddr) ||
1532             skb->protocol != htons(ETH_P_IP))
1533                 goto e_inval;
1534 
1535         if (ipv4_is_loopback(saddr) && !IN_DEV_ROUTE_LOCALNET(in_dev))
1536                 goto e_inval;
1537 
1538         if (ipv4_is_zeronet(saddr)) {
1539                 if (!ipv4_is_local_multicast(daddr))
1540                         goto e_inval;
1541         } else {
1542                 err = fib_validate_source(skb, saddr, 0, tos, 0, dev,
1543                                           in_dev, &itag);
1544                 if (err < 0)
1545                         goto e_err;
1546         }
1547         if (our)
1548                 flags |= RTCF_LOCAL;
1549 
1550         rth = rt_dst_alloc(dev_net(dev)->loopback_dev, flags, RTN_MULTICAST,
1551                            IN_DEV_CONF_GET(in_dev, NOPOLICY), false, false);
1552         if (!rth)
1553                 goto e_nobufs;
1554 
1555 #ifdef CONFIG_IP_ROUTE_CLASSID
1556         rth->dst.tclassid = itag;
1557 #endif
1558         rth->dst.output = ip_rt_bug;
1559         rth->rt_is_input= 1;
1560 
1561 #ifdef CONFIG_IP_MROUTE
1562         if (!ipv4_is_local_multicast(daddr) && IN_DEV_MFORWARD(in_dev))
1563                 rth->dst.input = ip_mr_input;
1564 #endif
1565         RT_CACHE_STAT_INC(in_slow_mc);
1566 
1567         skb_dst_set(skb, &rth->dst);
1568         return 0;
1569 
1570 e_nobufs:
1571         return -ENOBUFS;
1572 e_inval:
1573         return -EINVAL;
1574 e_err:
1575         return err;
1576 }
1577 
1578 
1579 static void ip_handle_martian_source(struct net_device *dev,
1580                                      struct in_device *in_dev,
1581                                      struct sk_buff *skb,
1582                                      __be32 daddr,
1583                                      __be32 saddr)
1584 {
1585         RT_CACHE_STAT_INC(in_martian_src);
1586 #ifdef CONFIG_IP_ROUTE_VERBOSE
1587         if (IN_DEV_LOG_MARTIANS(in_dev) && net_ratelimit()) {
1588                 /*
1589                  *      RFC1812 recommendation, if source is martian,
1590                  *      the only hint is MAC header.
1591                  */
1592                 pr_warn("martian source %pI4 from %pI4, on dev %s\n",
1593                         &daddr, &saddr, dev->name);
1594                 if (dev->hard_header_len && skb_mac_header_was_set(skb)) {
1595                         print_hex_dump(KERN_WARNING, "ll header: ",
1596                                        DUMP_PREFIX_OFFSET, 16, 1,
1597                                        skb_mac_header(skb),
1598                                        dev->hard_header_len, true);
1599                 }
1600         }
1601 #endif
1602 }
1603 
1604 static void ip_del_fnhe(struct fib_nh *nh, __be32 daddr)
1605 {
1606         struct fnhe_hash_bucket *hash;
1607         struct fib_nh_exception *fnhe, __rcu **fnhe_p;
1608         u32 hval = fnhe_hashfun(daddr);
1609 
1610         spin_lock_bh(&fnhe_lock);
1611 
1612         hash = rcu_dereference_protected(nh->nh_exceptions,
1613                                          lockdep_is_held(&fnhe_lock));
1614         hash += hval;
1615 
1616         fnhe_p = &hash->chain;
1617         fnhe = rcu_dereference_protected(*fnhe_p, lockdep_is_held(&fnhe_lock));
1618         while (fnhe) {
1619                 if (fnhe->fnhe_daddr == daddr) {
1620                         rcu_assign_pointer(*fnhe_p, rcu_dereference_protected(
1621                                 fnhe->fnhe_next, lockdep_is_held(&fnhe_lock)));
1622                         fnhe_flush_routes(fnhe);
1623                         kfree_rcu(fnhe, rcu);
1624                         break;
1625                 }
1626                 fnhe_p = &fnhe->fnhe_next;
1627                 fnhe = rcu_dereference_protected(fnhe->fnhe_next,
1628                                                  lockdep_is_held(&fnhe_lock));
1629         }
1630 
1631         spin_unlock_bh(&fnhe_lock);
1632 }
1633 
1634 static void set_lwt_redirect(struct rtable *rth)
1635 {
1636         if (lwtunnel_output_redirect(rth->dst.lwtstate)) {
1637                 rth->dst.lwtstate->orig_output = rth->dst.output;
1638                 rth->dst.output = lwtunnel_output;
1639         }
1640 
1641         if (lwtunnel_input_redirect(rth->dst.lwtstate)) {
1642                 rth->dst.lwtstate->orig_input = rth->dst.input;
1643                 rth->dst.input = lwtunnel_input;
1644         }
1645 }
1646 
1647 /* called in rcu_read_lock() section */
1648 static int __mkroute_input(struct sk_buff *skb,
1649                            const struct fib_result *res,
1650                            struct in_device *in_dev,
1651                            __be32 daddr, __be32 saddr, u32 tos)
1652 {
1653         struct fib_nh_exception *fnhe;
1654         struct rtable *rth;
1655         int err;
1656         struct in_device *out_dev;
1657         bool do_cache;
1658         u32 itag = 0;
1659 
1660         /* get a working reference to the output device */
1661         out_dev = __in_dev_get_rcu(FIB_RES_DEV(*res));
1662         if (!out_dev) {
1663                 net_crit_ratelimited("Bug in ip_route_input_slow(). Please report.\n");
1664                 return -EINVAL;
1665         }
1666 
1667         err = fib_validate_source(skb, saddr, daddr, tos, FIB_RES_OIF(*res),
1668                                   in_dev->dev, in_dev, &itag);
1669         if (err < 0) {
1670                 ip_handle_martian_source(in_dev->dev, in_dev, skb, daddr,
1671                                          saddr);
1672 
1673                 goto cleanup;
1674         }
1675 
1676         do_cache = res->fi && !itag;
1677         if (out_dev == in_dev && err && IN_DEV_TX_REDIRECTS(out_dev) &&
1678             skb->protocol == htons(ETH_P_IP) &&
1679             (IN_DEV_SHARED_MEDIA(out_dev) ||
1680              inet_addr_onlink(out_dev, saddr, FIB_RES_GW(*res))))
1681                 IPCB(skb)->flags |= IPSKB_DOREDIRECT;
1682 
1683         if (skb->protocol != htons(ETH_P_IP)) {
1684                 /* Not IP (i.e. ARP). Do not create route, if it is
1685                  * invalid for proxy arp. DNAT routes are always valid.
1686                  *
1687                  * Proxy arp feature have been extended to allow, ARP
1688                  * replies back to the same interface, to support
1689                  * Private VLAN switch technologies. See arp.c.
1690                  */
1691                 if (out_dev == in_dev &&
1692                     IN_DEV_PROXY_ARP_PVLAN(in_dev) == 0) {
1693                         err = -EINVAL;
1694                         goto cleanup;
1695                 }
1696         }
1697 
1698         fnhe = find_exception(&FIB_RES_NH(*res), daddr);
1699         if (do_cache) {
1700                 if (fnhe) {
1701                         rth = rcu_dereference(fnhe->fnhe_rth_input);
1702                         if (rth && rth->dst.expires &&
1703                             time_after(jiffies, rth->dst.expires)) {
1704                                 ip_del_fnhe(&FIB_RES_NH(*res), daddr);
1705                                 fnhe = NULL;
1706                         } else {
1707                                 goto rt_cache;
1708                         }
1709                 }
1710 
1711                 rth = rcu_dereference(FIB_RES_NH(*res).nh_rth_input);
1712 
1713 rt_cache:
1714                 if (rt_cache_valid(rth)) {
1715                         skb_dst_set_noref(skb, &rth->dst);
1716                         goto out;
1717                 }
1718         }
1719 
1720         rth = rt_dst_alloc(out_dev->dev, 0, res->type,
1721                            IN_DEV_CONF_GET(in_dev, NOPOLICY),
1722                            IN_DEV_CONF_GET(out_dev, NOXFRM), do_cache);
1723         if (!rth) {
1724                 err = -ENOBUFS;
1725                 goto cleanup;
1726         }
1727 
1728         rth->rt_is_input = 1;
1729         if (res->table)
1730                 rth->rt_table_id = res->table->tb_id;
1731         RT_CACHE_STAT_INC(in_slow_tot);
1732 
1733         rth->dst.input = ip_forward;
1734 
1735         rt_set_nexthop(rth, daddr, res, fnhe, res->fi, res->type, itag);
1736         set_lwt_redirect(rth);
1737         skb_dst_set(skb, &rth->dst);
1738 out:
1739         err = 0;
1740  cleanup:
1741         return err;
1742 }
1743 
1744 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1745 
1746 /* To make ICMP packets follow the right flow, the multipath hash is
1747  * calculated from the inner IP addresses in reverse order.
1748  */
1749 static int ip_multipath_icmp_hash(struct sk_buff *skb)
1750 {
1751         const struct iphdr *outer_iph = ip_hdr(skb);
1752         struct icmphdr _icmph;
1753         const struct icmphdr *icmph;
1754         struct iphdr _inner_iph;
1755         const struct iphdr *inner_iph;
1756 
1757         if (unlikely((outer_iph->frag_off & htons(IP_OFFSET)) != 0))
1758                 goto standard_hash;
1759 
1760         icmph = skb_header_pointer(skb, outer_iph->ihl * 4, sizeof(_icmph),
1761                                    &_icmph);
1762         if (!icmph)
1763                 goto standard_hash;
1764 
1765         if (icmph->type != ICMP_DEST_UNREACH &&
1766             icmph->type != ICMP_REDIRECT &&
1767             icmph->type != ICMP_TIME_EXCEEDED &&
1768             icmph->type != ICMP_PARAMETERPROB) {
1769                 goto standard_hash;
1770         }
1771 
1772         inner_iph = skb_header_pointer(skb,
1773                                        outer_iph->ihl * 4 + sizeof(_icmph),
1774                                        sizeof(_inner_iph), &_inner_iph);
1775         if (!inner_iph)
1776                 goto standard_hash;
1777 
1778         return fib_multipath_hash(inner_iph->daddr, inner_iph->saddr);
1779 
1780 standard_hash:
1781         return fib_multipath_hash(outer_iph->saddr, outer_iph->daddr);
1782 }
1783 
1784 #endif /* CONFIG_IP_ROUTE_MULTIPATH */
1785 
1786 static int ip_mkroute_input(struct sk_buff *skb,
1787                             struct fib_result *res,
1788                             struct in_device *in_dev,
1789                             __be32 daddr, __be32 saddr, u32 tos)
1790 {
1791 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1792         if (res->fi && res->fi->fib_nhs > 1) {
1793                 int h;
1794 
1795                 if (unlikely(ip_hdr(skb)->protocol == IPPROTO_ICMP))
1796                         h = ip_multipath_icmp_hash(skb);
1797                 else
1798                         h = fib_multipath_hash(saddr, daddr);
1799                 fib_select_multipath(res, h);
1800         }
1801 #endif
1802 
1803         /* create a routing cache entry */
1804         return __mkroute_input(skb, res, in_dev, daddr, saddr, tos);
1805 }
1806 
1807 /*
1808  *      NOTE. We drop all the packets that has local source
1809  *      addresses, because every properly looped back packet
1810  *      must have correct destination already attached by output routine.
1811  *
1812  *      Such approach solves two big problems:
1813  *      1. Not simplex devices are handled properly.
1814  *      2. IP spoofing attempts are filtered with 100% of guarantee.
1815  *      called with rcu_read_lock()
1816  */
1817 
1818 static int ip_route_input_slow(struct sk_buff *skb, __be32 daddr, __be32 saddr,
1819                                u8 tos, struct net_device *dev)
1820 {
1821         struct fib_result res;
1822         struct in_device *in_dev = __in_dev_get_rcu(dev);
1823         struct ip_tunnel_info *tun_info;
1824         struct flowi4   fl4;
1825         unsigned int    flags = 0;
1826         u32             itag = 0;
1827         struct rtable   *rth;
1828         int             err = -EINVAL;
1829         struct net    *net = dev_net(dev);
1830         bool do_cache;
1831 
1832         /* IP on this device is disabled. */
1833 
1834         if (!in_dev)
1835                 goto out;
1836 
1837         /* Check for the most weird martians, which can be not detected
1838            by fib_lookup.
1839          */
1840 
1841         tun_info = skb_tunnel_info(skb);
1842         if (tun_info && !(tun_info->mode & IP_TUNNEL_INFO_TX))
1843                 fl4.flowi4_tun_key.tun_id = tun_info->key.tun_id;
1844         else
1845                 fl4.flowi4_tun_key.tun_id = 0;
1846         skb_dst_drop(skb);
1847 
1848         if (ipv4_is_multicast(saddr) || ipv4_is_lbcast(saddr))
1849                 goto martian_source;
1850 
1851         res.fi = NULL;
1852         res.table = NULL;
1853         if (ipv4_is_lbcast(daddr) || (saddr == 0 && daddr == 0))
1854                 goto brd_input;
1855 
1856         /* Accept zero addresses only to limited broadcast;
1857          * I even do not know to fix it or not. Waiting for complains :-)
1858          */
1859         if (ipv4_is_zeronet(saddr))
1860                 goto martian_source;
1861 
1862         if (ipv4_is_zeronet(daddr))
1863                 goto martian_destination;
1864 
1865         /* Following code try to avoid calling IN_DEV_NET_ROUTE_LOCALNET(),
1866          * and call it once if daddr or/and saddr are loopback addresses
1867          */
1868         if (ipv4_is_loopback(daddr)) {
1869                 if (!IN_DEV_NET_ROUTE_LOCALNET(in_dev, net))
1870                         goto martian_destination;
1871         } else if (ipv4_is_loopback(saddr)) {
1872                 if (!IN_DEV_NET_ROUTE_LOCALNET(in_dev, net))
1873                         goto martian_source;
1874         }
1875 
1876         /*
1877          *      Now we are ready to route packet.
1878          */
1879         fl4.flowi4_oif = 0;
1880         fl4.flowi4_iif = dev->ifindex;
1881         fl4.flowi4_mark = skb->mark;
1882         fl4.flowi4_tos = tos;
1883         fl4.flowi4_scope = RT_SCOPE_UNIVERSE;
1884         fl4.flowi4_flags = 0;
1885         fl4.daddr = daddr;
1886         fl4.saddr = saddr;
1887         fl4.flowi4_uid = sock_net_uid(net, NULL);
1888         err = fib_lookup(net, &fl4, &res, 0);
1889         if (err != 0) {
1890                 if (!IN_DEV_FORWARD(in_dev))
1891                         err = -EHOSTUNREACH;
1892                 goto no_route;
1893         }
1894 
1895         if (res.type == RTN_BROADCAST)
1896                 goto brd_input;
1897 
1898         if (res.type == RTN_LOCAL) {
1899                 err = fib_validate_source(skb, saddr, daddr, tos,
1900                                           0, dev, in_dev, &itag);
1901                 if (err < 0)
1902                         goto martian_source;
1903                 goto local_input;
1904         }
1905 
1906         if (!IN_DEV_FORWARD(in_dev)) {
1907                 err = -EHOSTUNREACH;
1908                 goto no_route;
1909         }
1910         if (res.type != RTN_UNICAST)
1911                 goto martian_destination;
1912 
1913         err = ip_mkroute_input(skb, &res, in_dev, daddr, saddr, tos);
1914 out:    return err;
1915 
1916 brd_input:
1917         if (skb->protocol != htons(ETH_P_IP))
1918                 goto e_inval;
1919 
1920         if (!ipv4_is_zeronet(saddr)) {
1921                 err = fib_validate_source(skb, saddr, 0, tos, 0, dev,
1922                                           in_dev, &itag);
1923                 if (err < 0)
1924                         goto martian_source;
1925         }
1926         flags |= RTCF_BROADCAST;
1927         res.type = RTN_BROADCAST;
1928         RT_CACHE_STAT_INC(in_brd);
1929 
1930 local_input:
1931         do_cache = false;
1932         if (res.fi) {
1933                 if (!itag) {
1934                         rth = rcu_dereference(FIB_RES_NH(res).nh_rth_input);
1935                         if (rt_cache_valid(rth)) {
1936                                 skb_dst_set_noref(skb, &rth->dst);
1937                                 err = 0;
1938                                 goto out;
1939                         }
1940                         do_cache = true;
1941                 }
1942         }
1943 
1944         rth = rt_dst_alloc(l3mdev_master_dev_rcu(dev) ? : net->loopback_dev,
1945                            flags | RTCF_LOCAL, res.type,
1946                            IN_DEV_CONF_GET(in_dev, NOPOLICY), false, do_cache);
1947         if (!rth)
1948                 goto e_nobufs;
1949 
1950         rth->dst.output= ip_rt_bug;
1951 #ifdef CONFIG_IP_ROUTE_CLASSID
1952         rth->dst.tclassid = itag;
1953 #endif
1954         rth->rt_is_input = 1;
1955         if (res.table)
1956                 rth->rt_table_id = res.table->tb_id;
1957 
1958         RT_CACHE_STAT_INC(in_slow_tot);
1959         if (res.type == RTN_UNREACHABLE) {
1960                 rth->dst.input= ip_error;
1961                 rth->dst.error= -err;
1962                 rth->rt_flags   &= ~RTCF_LOCAL;
1963         }
1964 
1965         if (do_cache) {
1966                 struct fib_nh *nh = &FIB_RES_NH(res);
1967 
1968                 rth->dst.lwtstate = lwtstate_get(nh->nh_lwtstate);
1969                 if (lwtunnel_input_redirect(rth->dst.lwtstate)) {
1970                         WARN_ON(rth->dst.input == lwtunnel_input);
1971                         rth->dst.lwtstate->orig_input = rth->dst.input;
1972                         rth->dst.input = lwtunnel_input;
1973                 }
1974 
1975                 if (unlikely(!rt_cache_route(nh, rth))) {
1976                         rth->dst.flags |= DST_NOCACHE;
1977                         rt_add_uncached_list(rth);
1978                 }
1979         }
1980         skb_dst_set(skb, &rth->dst);
1981         err = 0;
1982         goto out;
1983 
1984 no_route:
1985         RT_CACHE_STAT_INC(in_no_route);
1986         res.type = RTN_UNREACHABLE;
1987         res.fi = NULL;
1988         res.table = NULL;
1989         goto local_input;
1990 
1991         /*
1992          *      Do not cache martian addresses: they should be logged (RFC1812)
1993          */
1994 martian_destination:
1995         RT_CACHE_STAT_INC(in_martian_dst);
1996 #ifdef CONFIG_IP_ROUTE_VERBOSE
1997         if (IN_DEV_LOG_MARTIANS(in_dev))
1998                 net_warn_ratelimited("martian destination %pI4 from %pI4, dev %s\n",
1999                                      &daddr, &saddr, dev->name);
2000 #endif
2001 
2002 e_inval:
2003         err = -EINVAL;
2004         goto out;
2005 
2006 e_nobufs:
2007         err = -ENOBUFS;
2008         goto out;
2009 
2010 martian_source:
2011         ip_handle_martian_source(dev, in_dev, skb, daddr, saddr);
2012         goto out;
2013 }
2014 
2015 int ip_route_input_noref(struct sk_buff *skb, __be32 daddr, __be32 saddr,
2016                          u8 tos, struct net_device *dev)
2017 {
2018         int res;
2019 
2020         tos &= IPTOS_RT_MASK;
2021         rcu_read_lock();
2022 
2023         /* Multicast recognition logic is moved from route cache to here.
2024            The problem was that too many Ethernet cards have broken/missing
2025            hardware multicast filters :-( As result the host on multicasting
2026            network acquires a lot of useless route cache entries, sort of
2027            SDR messages from all the world. Now we try to get rid of them.
2028            Really, provided software IP multicast filter is organized
2029            reasonably (at least, hashed), it does not result in a slowdown
2030            comparing with route cache reject entries.
2031            Note, that multicast routers are not affected, because
2032            route cache entry is created eventually.
2033          */
2034         if (ipv4_is_multicast(daddr)) {
2035                 struct in_device *in_dev = __in_dev_get_rcu(dev);
2036                 int our = 0;
2037 
2038                 if (in_dev)
2039                         our = ip_check_mc_rcu(in_dev, daddr, saddr,
2040                                               ip_hdr(skb)->protocol);
2041 
2042                 /* check l3 master if no match yet */
2043                 if ((!in_dev || !our) && netif_is_l3_slave(dev)) {
2044                         struct in_device *l3_in_dev;
2045 
2046                         l3_in_dev = __in_dev_get_rcu(skb->dev);
2047                         if (l3_in_dev)
2048                                 our = ip_check_mc_rcu(l3_in_dev, daddr, saddr,
2049                                                       ip_hdr(skb)->protocol);
2050                 }
2051 
2052                 res = -EINVAL;
2053                 if (our
2054 #ifdef CONFIG_IP_MROUTE
2055                         ||
2056                     (!ipv4_is_local_multicast(daddr) &&
2057                      IN_DEV_MFORWARD(in_dev))
2058 #endif
2059                    ) {
2060                         res = ip_route_input_mc(skb, daddr, saddr,
2061                                                 tos, dev, our);
2062                 }
2063                 rcu_read_unlock();
2064                 return res;
2065         }
2066         res = ip_route_input_slow(skb, daddr, saddr, tos, dev);
2067         rcu_read_unlock();
2068         return res;
2069 }
2070 EXPORT_SYMBOL(ip_route_input_noref);
2071 
2072 /* called with rcu_read_lock() */
2073 static struct rtable *__mkroute_output(const struct fib_result *res,
2074                                        const struct flowi4 *fl4, int orig_oif,
2075                                        struct net_device *dev_out,
2076                                        unsigned int flags)
2077 {
2078         struct fib_info *fi = res->fi;
2079         struct fib_nh_exception *fnhe;
2080         struct in_device *in_dev;
2081         u16 type = res->type;
2082         struct rtable *rth;
2083         bool do_cache;
2084 
2085         in_dev = __in_dev_get_rcu(dev_out);
2086         if (!in_dev)
2087                 return ERR_PTR(-EINVAL);
2088 
2089         if (likely(!IN_DEV_ROUTE_LOCALNET(in_dev)))
2090                 if (ipv4_is_loopback(fl4->saddr) &&
2091                     !(dev_out->flags & IFF_LOOPBACK) &&
2092                     !netif_is_l3_master(dev_out))
2093                         return ERR_PTR(-EINVAL);
2094 
2095         if (ipv4_is_lbcast(fl4->daddr))
2096                 type = RTN_BROADCAST;
2097         else if (ipv4_is_multicast(fl4->daddr))
2098                 type = RTN_MULTICAST;
2099         else if (ipv4_is_zeronet(fl4->daddr))
2100                 return ERR_PTR(-EINVAL);
2101 
2102         if (dev_out->flags & IFF_LOOPBACK)
2103                 flags |= RTCF_LOCAL;
2104 
2105         do_cache = true;
2106         if (type == RTN_BROADCAST) {
2107                 flags |= RTCF_BROADCAST | RTCF_LOCAL;
2108                 fi = NULL;
2109         } else if (type == RTN_MULTICAST) {
2110                 flags |= RTCF_MULTICAST | RTCF_LOCAL;
2111                 if (!ip_check_mc_rcu(in_dev, fl4->daddr, fl4->saddr,
2112                                      fl4->flowi4_proto))
2113                         flags &= ~RTCF_LOCAL;
2114                 else
2115                         do_cache = false;
2116                 /* If multicast route do not exist use
2117                  * default one, but do not gateway in this case.
2118                  * Yes, it is hack.
2119                  */
2120                 if (fi && res->prefixlen < 4)
2121                         fi = NULL;
2122         } else if ((type == RTN_LOCAL) && (orig_oif != 0) &&
2123                    (orig_oif != dev_out->ifindex)) {
2124                 /* For local routes that require a particular output interface
2125                  * we do not want to cache the result.  Caching the result
2126                  * causes incorrect behaviour when there are multiple source
2127                  * addresses on the interface, the end result being that if the
2128                  * intended recipient is waiting on that interface for the
2129                  * packet he won't receive it because it will be delivered on
2130                  * the loopback interface and the IP_PKTINFO ipi_ifindex will
2131                  * be set to the loopback interface as well.
2132                  */
2133                 fi = NULL;
2134         }
2135 
2136         fnhe = NULL;
2137         do_cache &= fi != NULL;
2138         if (do_cache) {
2139                 struct rtable __rcu **prth;
2140                 struct fib_nh *nh = &FIB_RES_NH(*res);
2141 
2142                 fnhe = find_exception(nh, fl4->daddr);
2143                 if (fnhe) {
2144                         prth = &fnhe->fnhe_rth_output;
2145                         rth = rcu_dereference(*prth);
2146                         if (rth && rth->dst.expires &&
2147                             time_after(jiffies, rth->dst.expires)) {
2148                                 ip_del_fnhe(nh, fl4->daddr);
2149                                 fnhe = NULL;
2150                         } else {
2151                                 goto rt_cache;
2152                         }
2153                 }
2154 
2155                 if (unlikely(fl4->flowi4_flags &
2156                              FLOWI_FLAG_KNOWN_NH &&
2157                              !(nh->nh_gw &&
2158                                nh->nh_scope == RT_SCOPE_LINK))) {
2159                         do_cache = false;
2160                         goto add;
2161                 }
2162                 prth = raw_cpu_ptr(nh->nh_pcpu_rth_output);
2163                 rth = rcu_dereference(*prth);
2164 
2165 rt_cache:
2166                 if (rt_cache_valid(rth)) {
2167                         dst_hold(&rth->dst);
2168                         return rth;
2169                 }
2170         }
2171 
2172 add:
2173         rth = rt_dst_alloc(dev_out, flags, type,
2174                            IN_DEV_CONF_GET(in_dev, NOPOLICY),
2175                            IN_DEV_CONF_GET(in_dev, NOXFRM),
2176                            do_cache);
2177         if (!rth)
2178                 return ERR_PTR(-ENOBUFS);
2179 
2180         rth->rt_iif     = orig_oif ? : 0;
2181         if (res->table)
2182                 rth->rt_table_id = res->table->tb_id;
2183 
2184         RT_CACHE_STAT_INC(out_slow_tot);
2185 
2186         if (flags & (RTCF_BROADCAST | RTCF_MULTICAST)) {
2187                 if (flags & RTCF_LOCAL &&
2188                     !(dev_out->flags & IFF_LOOPBACK)) {
2189                         rth->dst.output = ip_mc_output;
2190                         RT_CACHE_STAT_INC(out_slow_mc);
2191                 }
2192 #ifdef CONFIG_IP_MROUTE
2193                 if (type == RTN_MULTICAST) {
2194                         if (IN_DEV_MFORWARD(in_dev) &&
2195                             !ipv4_is_local_multicast(fl4->daddr)) {
2196                                 rth->dst.input = ip_mr_input;
2197                                 rth->dst.output = ip_mc_output;
2198                         }
2199                 }
2200 #endif
2201         }
2202 
2203         rt_set_nexthop(rth, fl4->daddr, res, fnhe, fi, type, 0);
2204         set_lwt_redirect(rth);
2205 
2206         return rth;
2207 }
2208 
2209 /*
2210  * Major route resolver routine.
2211  */
2212 
2213 struct rtable *__ip_route_output_key_hash(struct net *net, struct flowi4 *fl4,
2214                                           int mp_hash)
2215 {
2216         struct net_device *dev_out = NULL;
2217         __u8 tos = RT_FL_TOS(fl4);
2218         unsigned int flags = 0;
2219         struct fib_result res;
2220         struct rtable *rth;
2221         int orig_oif;
2222         int err = -ENETUNREACH;
2223 
2224         res.tclassid    = 0;
2225         res.fi          = NULL;
2226         res.table       = NULL;
2227 
2228         orig_oif = fl4->flowi4_oif;
2229 
2230         fl4->flowi4_iif = LOOPBACK_IFINDEX;
2231         fl4->flowi4_tos = tos & IPTOS_RT_MASK;
2232         fl4->flowi4_scope = ((tos & RTO_ONLINK) ?
2233                          RT_SCOPE_LINK : RT_SCOPE_UNIVERSE);
2234 
2235         rcu_read_lock();
2236         if (fl4->saddr) {
2237                 rth = ERR_PTR(-EINVAL);
2238                 if (ipv4_is_multicast(fl4->saddr) ||
2239                     ipv4_is_lbcast(fl4->saddr) ||
2240                     ipv4_is_zeronet(fl4->saddr))
2241                         goto out;
2242 
2243                 /* I removed check for oif == dev_out->oif here.
2244                    It was wrong for two reasons:
2245                    1. ip_dev_find(net, saddr) can return wrong iface, if saddr
2246                       is assigned to multiple interfaces.
2247                    2. Moreover, we are allowed to send packets with saddr
2248                       of another iface. --ANK
2249                  */
2250 
2251                 if (fl4->flowi4_oif == 0 &&
2252                     (ipv4_is_multicast(fl4->daddr) ||
2253                      ipv4_is_lbcast(fl4->daddr))) {
2254                         /* It is equivalent to inet_addr_type(saddr) == RTN_LOCAL */
2255                         dev_out = __ip_dev_find(net, fl4->saddr, false);
2256                         if (!dev_out)
2257                                 goto out;
2258 
2259                         /* Special hack: user can direct multicasts
2260                            and limited broadcast via necessary interface
2261                            without fiddling with IP_MULTICAST_IF or IP_PKTINFO.
2262                            This hack is not just for fun, it allows
2263                            vic,vat and friends to work.
2264                            They bind socket to loopback, set ttl to zero
2265                            and expect that it will work.
2266                            From the viewpoint of routing cache they are broken,
2267                            because we are not allowed to build multicast path
2268                            with loopback source addr (look, routing cache
2269                            cannot know, that ttl is zero, so that packet
2270                            will not leave this host and route is valid).
2271                            Luckily, this hack is good workaround.
2272                          */
2273 
2274                         fl4->flowi4_oif = dev_out->ifindex;
2275                         goto make_route;
2276                 }
2277 
2278                 if (!(fl4->flowi4_flags & FLOWI_FLAG_ANYSRC)) {
2279                         /* It is equivalent to inet_addr_type(saddr) == RTN_LOCAL */
2280                         if (!__ip_dev_find(net, fl4->saddr, false))
2281                                 goto out;
2282                 }
2283         }
2284 
2285 
2286         if (fl4->flowi4_oif) {
2287                 dev_out = dev_get_by_index_rcu(net, fl4->flowi4_oif);
2288                 rth = ERR_PTR(-ENODEV);
2289                 if (!dev_out)
2290                         goto out;
2291 
2292                 /* RACE: Check return value of inet_select_addr instead. */
2293                 if (!(dev_out->flags & IFF_UP) || !__in_dev_get_rcu(dev_out)) {
2294                         rth = ERR_PTR(-ENETUNREACH);
2295                         goto out;
2296                 }
2297                 if (ipv4_is_local_multicast(fl4->daddr) ||
2298                     ipv4_is_lbcast(fl4->daddr) ||
2299                     fl4->flowi4_proto == IPPROTO_IGMP) {
2300                         if (!fl4->saddr)
2301                                 fl4->saddr = inet_select_addr(dev_out, 0,
2302                                                               RT_SCOPE_LINK);
2303                         goto make_route;
2304                 }
2305                 if (!fl4->saddr) {
2306                         if (ipv4_is_multicast(fl4->daddr))
2307                                 fl4->saddr = inet_select_addr(dev_out, 0,
2308                                                               fl4->flowi4_scope);
2309                         else if (!fl4->daddr)
2310                                 fl4->saddr = inet_select_addr(dev_out, 0,
2311                                                               RT_SCOPE_HOST);
2312                 }
2313         }
2314 
2315         if (!fl4->daddr) {
2316                 fl4->daddr = fl4->saddr;
2317                 if (!fl4->daddr)
2318                         fl4->daddr = fl4->saddr = htonl(INADDR_LOOPBACK);
2319                 dev_out = net->loopback_dev;
2320                 fl4->flowi4_oif = LOOPBACK_IFINDEX;
2321                 res.type = RTN_LOCAL;
2322                 flags |= RTCF_LOCAL;
2323                 goto make_route;
2324         }
2325 
2326         err = fib_lookup(net, fl4, &res, 0);
2327         if (err) {
2328                 res.fi = NULL;
2329                 res.table = NULL;
2330                 if (fl4->flowi4_oif &&
2331                     (ipv4_is_multicast(fl4->daddr) ||
2332                     !netif_index_is_l3_master(net, fl4->flowi4_oif))) {
2333                         /* Apparently, routing tables are wrong. Assume,
2334                            that the destination is on link.
2335 
2336                            WHY? DW.
2337                            Because we are allowed to send to iface
2338                            even if it has NO routes and NO assigned
2339                            addresses. When oif is specified, routing
2340                            tables are looked up with only one purpose:
2341                            to catch if destination is gatewayed, rather than
2342                            direct. Moreover, if MSG_DONTROUTE is set,
2343                            we send packet, ignoring both routing tables
2344                            and ifaddr state. --ANK
2345 
2346 
2347                            We could make it even if oif is unknown,
2348                            likely IPv6, but we do not.
2349                          */
2350 
2351                         if (fl4->saddr == 0)
2352                                 fl4->saddr = inet_select_addr(dev_out, 0,
2353                                                               RT_SCOPE_LINK);
2354                         res.type = RTN_UNICAST;
2355                         goto make_route;
2356                 }
2357                 rth = ERR_PTR(err);
2358                 goto out;
2359         }
2360 
2361         if (res.type == RTN_LOCAL) {
2362                 if (!fl4->saddr) {
2363                         if (res.fi->fib_prefsrc)
2364                                 fl4->saddr = res.fi->fib_prefsrc;
2365                         else
2366                                 fl4->saddr = fl4->daddr;
2367                 }
2368 
2369                 /* L3 master device is the loopback for that domain */
2370                 dev_out = l3mdev_master_dev_rcu(FIB_RES_DEV(res)) ? :
2371                         net->loopback_dev;
2372                 fl4->flowi4_oif = dev_out->ifindex;
2373                 flags |= RTCF_LOCAL;
2374                 goto make_route;
2375         }
2376 
2377         fib_select_path(net, &res, fl4, mp_hash);
2378 
2379         dev_out = FIB_RES_DEV(res);
2380         fl4->flowi4_oif = dev_out->ifindex;
2381 
2382 
2383 make_route:
2384         rth = __mkroute_output(&res, fl4, orig_oif, dev_out, flags);
2385 
2386 out:
2387         rcu_read_unlock();
2388         return rth;
2389 }
2390 EXPORT_SYMBOL_GPL(__ip_route_output_key_hash);
2391 
2392 static struct dst_entry *ipv4_blackhole_dst_check(struct dst_entry *dst, u32 cookie)
2393 {
2394         return NULL;
2395 }
2396 
2397 static unsigned int ipv4_blackhole_mtu(const struct dst_entry *dst)
2398 {
2399         unsigned int mtu = dst_metric_raw(dst, RTAX_MTU);
2400 
2401         return mtu ? : dst->dev->mtu;
2402 }
2403 
2404 static void ipv4_rt_blackhole_update_pmtu(struct dst_entry *dst, struct sock *sk,
2405                                           struct sk_buff *skb, u32 mtu)
2406 {
2407 }
2408 
2409 static void ipv4_rt_blackhole_redirect(struct dst_entry *dst, struct sock *sk,
2410                                        struct sk_buff *skb)
2411 {
2412 }
2413 
2414 static u32 *ipv4_rt_blackhole_cow_metrics(struct dst_entry *dst,
2415                                           unsigned long old)
2416 {
2417         return NULL;
2418 }
2419 
2420 static struct dst_ops ipv4_dst_blackhole_ops = {
2421         .family                 =       AF_INET,
2422         .check                  =       ipv4_blackhole_dst_check,
2423         .mtu                    =       ipv4_blackhole_mtu,
2424         .default_advmss         =       ipv4_default_advmss,
2425         .update_pmtu            =       ipv4_rt_blackhole_update_pmtu,
2426         .redirect               =       ipv4_rt_blackhole_redirect,
2427         .cow_metrics            =       ipv4_rt_blackhole_cow_metrics,
2428         .neigh_lookup           =       ipv4_neigh_lookup,
2429 };
2430 
2431 struct dst_entry *ipv4_blackhole_route(struct net *net, struct dst_entry *dst_orig)
2432 {
2433         struct rtable *ort = (struct rtable *) dst_orig;
2434         struct rtable *rt;
2435 
2436         rt = dst_alloc(&ipv4_dst_blackhole_ops, NULL, 1, DST_OBSOLETE_NONE, 0);
2437         if (rt) {
2438                 struct dst_entry *new = &rt->dst;
2439 
2440                 new->__use = 1;
2441                 new->input = dst_discard;
2442                 new->output = dst_discard_out;
2443 
2444                 new->dev = ort->dst.dev;
2445                 if (new->dev)
2446                         dev_hold(new->dev);
2447 
2448                 rt->rt_is_input = ort->rt_is_input;
2449                 rt->rt_iif = ort->rt_iif;
2450                 rt->rt_pmtu = ort->rt_pmtu;
2451 
2452                 rt->rt_genid = rt_genid_ipv4(net);
2453                 rt->rt_flags = ort->rt_flags;
2454                 rt->rt_type = ort->rt_type;
2455                 rt->rt_gateway = ort->rt_gateway;
2456                 rt->rt_uses_gateway = ort->rt_uses_gateway;
2457 
2458                 INIT_LIST_HEAD(&rt->rt_uncached);
2459                 dst_free(new);
2460         }
2461 
2462         dst_release(dst_orig);
2463 
2464         return rt ? &rt->dst : ERR_PTR(-ENOMEM);
2465 }
2466 
2467 struct rtable *ip_route_output_flow(struct net *net, struct flowi4 *flp4,
2468                                     const struct sock *sk)
2469 {
2470         struct rtable *rt = __ip_route_output_key(net, flp4);
2471 
2472         if (IS_ERR(rt))
2473                 return rt;
2474 
2475         if (flp4->flowi4_proto)
2476                 rt = (struct rtable *)xfrm_lookup_route(net, &rt->dst,
2477                                                         flowi4_to_flowi(flp4),
2478                                                         sk, 0);
2479 
2480         return rt;
2481 }
2482 EXPORT_SYMBOL_GPL(ip_route_output_flow);
2483 
2484 static int rt_fill_info(struct net *net,  __be32 dst, __be32 src, u32 table_id,
2485                         struct flowi4 *fl4, struct sk_buff *skb, u32 portid,
2486                         u32 seq, int event)
2487 {
2488         struct rtable *rt = skb_rtable(skb);
2489         struct rtmsg *r;
2490         struct nlmsghdr *nlh;
2491         unsigned long expires = 0;
2492         u32 error;
2493         u32 metrics[RTAX_MAX];
2494 
2495         nlh = nlmsg_put(skb, portid, seq, event, sizeof(*r), 0);
2496         if (!nlh)
2497                 return -EMSGSIZE;
2498 
2499         r = nlmsg_data(nlh);
2500         r->rtm_family    = AF_INET;
2501         r->rtm_dst_len  = 32;
2502         r->rtm_src_len  = 0;
2503         r->rtm_tos      = fl4->flowi4_tos;
2504         r->rtm_table    = table_id < 256 ? table_id : RT_TABLE_COMPAT;
2505         if (nla_put_u32(skb, RTA_TABLE, table_id))
2506                 goto nla_put_failure;
2507         r->rtm_type     = rt->rt_type;
2508         r->rtm_scope    = RT_SCOPE_UNIVERSE;
2509         r->rtm_protocol = RTPROT_UNSPEC;
2510         r->rtm_flags    = (rt->rt_flags & ~0xFFFF) | RTM_F_CLONED;
2511         if (rt->rt_flags & RTCF_NOTIFY)
2512                 r->rtm_flags |= RTM_F_NOTIFY;
2513         if (IPCB(skb)->flags & IPSKB_DOREDIRECT)
2514                 r->rtm_flags |= RTCF_DOREDIRECT;
2515 
2516         if (nla_put_in_addr(skb, RTA_DST, dst))
2517                 goto nla_put_failure;
2518         if (src) {
2519                 r->rtm_src_len = 32;
2520                 if (nla_put_in_addr(skb, RTA_SRC, src))
2521                         goto nla_put_failure;
2522         }
2523         if (rt->dst.dev &&
2524             nla_put_u32(skb, RTA_OIF, rt->dst.dev->ifindex))
2525                 goto nla_put_failure;
2526 #ifdef CONFIG_IP_ROUTE_CLASSID
2527         if (rt->dst.tclassid &&
2528             nla_put_u32(skb, RTA_FLOW, rt->dst.tclassid))
2529                 goto nla_put_failure;
2530 #endif
2531         if (!rt_is_input_route(rt) &&
2532             fl4->saddr != src) {
2533                 if (nla_put_in_addr(skb, RTA_PREFSRC, fl4->saddr))
2534                         goto nla_put_failure;
2535         }
2536         if (rt->rt_uses_gateway &&
2537             nla_put_in_addr(skb, RTA_GATEWAY, rt->rt_gateway))
2538                 goto nla_put_failure;
2539 
2540         expires = rt->dst.expires;
2541         if (expires) {
2542                 unsigned long now = jiffies;
2543 
2544                 if (time_before(now, expires))
2545                         expires -= now;
2546                 else
2547                         expires = 0;
2548         }
2549 
2550         memcpy(metrics, dst_metrics_ptr(&rt->dst), sizeof(metrics));
2551         if (rt->rt_pmtu && expires)
2552                 metrics[RTAX_MTU - 1] = rt->rt_pmtu;
2553         if (rtnetlink_put_metrics(skb, metrics) < 0)
2554                 goto nla_put_failure;
2555 
2556         if (fl4->flowi4_mark &&
2557             nla_put_u32(skb, RTA_MARK, fl4->flowi4_mark))
2558                 goto nla_put_failure;
2559 
2560         if (!uid_eq(fl4->flowi4_uid, INVALID_UID) &&
2561             nla_put_u32(skb, RTA_UID,
2562                         from_kuid_munged(current_user_ns(), fl4->flowi4_uid)))
2563                 goto nla_put_failure;
2564 
2565         error = rt->dst.error;
2566 
2567         if (rt_is_input_route(rt)) {
2568 #ifdef CONFIG_IP_MROUTE
2569                 if (ipv4_is_multicast(dst) && !ipv4_is_local_multicast(dst) &&
2570                     IPV4_DEVCONF_ALL(net, MC_FORWARDING)) {
2571                         int err = ipmr_get_route(net, skb,
2572                                                  fl4->saddr, fl4->daddr,
2573                                                  r, portid);
2574 
2575                         if (err <= 0) {
2576                                 if (err == 0)
2577                                         return 0;
2578                                 goto nla_put_failure;
2579                         }
2580                 } else
2581 #endif
2582                         if (nla_put_u32(skb, RTA_IIF, skb->dev->ifindex))
2583                                 goto nla_put_failure;
2584         }
2585 
2586         if (rtnl_put_cacheinfo(skb, &rt->dst, 0, expires, error) < 0)
2587                 goto nla_put_failure;
2588 
2589         nlmsg_end(skb, nlh);
2590         return 0;
2591 
2592 nla_put_failure:
2593         nlmsg_cancel(skb, nlh);
2594         return -EMSGSIZE;
2595 }
2596 
2597 static int inet_rtm_getroute(struct sk_buff *in_skb, struct nlmsghdr *nlh)
2598 {
2599         struct net *net = sock_net(in_skb->sk);
2600         struct rtmsg *rtm;
2601         struct nlattr *tb[RTA_MAX+1];
2602         struct rtable *rt = NULL;
2603         struct flowi4 fl4;
2604         __be32 dst = 0;
2605         __be32 src = 0;
2606         u32 iif;
2607         int err;
2608         int mark;
2609         struct sk_buff *skb;
2610         u32 table_id = RT_TABLE_MAIN;
2611         kuid_t uid;
2612 
2613         err = nlmsg_parse(nlh, sizeof(*rtm), tb, RTA_MAX, rtm_ipv4_policy);
2614         if (err < 0)
2615                 goto errout;
2616 
2617         rtm = nlmsg_data(nlh);
2618 
2619         skb = alloc_skb(NLMSG_GOODSIZE, GFP_KERNEL);
2620         if (!skb) {
2621                 err = -ENOBUFS;
2622                 goto errout;
2623         }
2624 
2625         /* Reserve room for dummy headers, this skb can pass
2626            through good chunk of routing engine.
2627          */
2628         skb_reset_mac_header(skb);
2629         skb_reset_network_header(skb);
2630 
2631         /* Bugfix: need to give ip_route_input enough of an IP header to not gag. */
2632         ip_hdr(skb)->protocol = IPPROTO_UDP;
2633         skb_reserve(skb, MAX_HEADER + sizeof(struct iphdr));
2634 
2635         src = tb[RTA_SRC] ? nla_get_in_addr(tb[RTA_SRC]) : 0;
2636         dst = tb[RTA_DST] ? nla_get_in_addr(tb[RTA_DST]) : 0;
2637         iif = tb[RTA_IIF] ? nla_get_u32(tb[RTA_IIF]) : 0;
2638         mark = tb[RTA_MARK] ? nla_get_u32(tb[RTA_MARK]) : 0;
2639         if (tb[RTA_UID])
2640                 uid = make_kuid(current_user_ns(), nla_get_u32(tb[RTA_UID]));
2641         else
2642                 uid = (iif ? INVALID_UID : current_uid());
2643 
2644         memset(&fl4, 0, sizeof(fl4));
2645         fl4.daddr = dst;
2646         fl4.saddr = src;
2647         fl4.flowi4_tos = rtm->rtm_tos;
2648         fl4.flowi4_oif = tb[RTA_OIF] ? nla_get_u32(tb[RTA_OIF]) : 0;
2649         fl4.flowi4_mark = mark;
2650         fl4.flowi4_uid = uid;
2651 
2652         if (iif) {
2653                 struct net_device *dev;
2654 
2655                 dev = __dev_get_by_index(net, iif);
2656                 if (!dev) {
2657                         err = -ENODEV;
2658                         goto errout_free;
2659                 }
2660 
2661                 skb->protocol   = htons(ETH_P_IP);
2662                 skb->dev        = dev;
2663                 skb->mark       = mark;
2664                 err = ip_route_input(skb, dst, src, rtm->rtm_tos, dev);
2665 
2666                 rt = skb_rtable(skb);
2667                 if (err == 0 && rt->dst.error)
2668                         err = -rt->dst.error;
2669         } else {
2670                 rt = ip_route_output_key(net, &fl4);
2671 
2672                 err = 0;
2673                 if (IS_ERR(rt))
2674                         err = PTR_ERR(rt);
2675         }
2676 
2677         if (err)
2678                 goto errout_free;
2679 
2680         skb_dst_set(skb, &rt->dst);
2681         if (rtm->rtm_flags & RTM_F_NOTIFY)
2682                 rt->rt_flags |= RTCF_NOTIFY;
2683 
2684         if (rtm->rtm_flags & RTM_F_LOOKUP_TABLE)
2685                 table_id = rt->rt_table_id;
2686 
2687         err = rt_fill_info(net, dst, src, table_id, &fl4, skb,
2688                            NETLINK_CB(in_skb).portid, nlh->nlmsg_seq,
2689                            RTM_NEWROUTE);
2690         if (err < 0)
2691                 goto errout_free;
2692 
2693         err = rtnl_unicast(skb, net, NETLINK_CB(in_skb).portid);
2694 errout:
2695         return err;
2696 
2697 errout_free:
2698         kfree_skb(skb);
2699         goto errout;
2700 }
2701 
2702 void ip_rt_multicast_event(struct in_device *in_dev)
2703 {
2704         rt_cache_flush(dev_net(in_dev->dev));
2705 }
2706 
2707 #ifdef CONFIG_SYSCTL
2708 static int ip_rt_gc_interval __read_mostly  = 60 * HZ;
2709 static int ip_rt_gc_min_interval __read_mostly  = HZ / 2;
2710 static int ip_rt_gc_elasticity __read_mostly    = 8;
2711 
2712 static int ipv4_sysctl_rtcache_flush(struct ctl_table *__ctl, int write,
2713                                         void __user *buffer,
2714                                         size_t *lenp, loff_t *ppos)
2715 {
2716         struct net *net = (struct net *)__ctl->extra1;
2717 
2718         if (write) {
2719                 rt_cache_flush(net);
2720                 fnhe_genid_bump(net);
2721                 return 0;
2722         }
2723 
2724         return -EINVAL;
2725 }
2726 
2727 static struct ctl_table ipv4_route_table[] = {
2728         {
2729                 .procname       = "gc_thresh",
2730                 .data           = &ipv4_dst_ops.gc_thresh,
2731                 .maxlen         = sizeof(int),
2732                 .mode           = 0644,
2733                 .proc_handler   = proc_dointvec,
2734         },
2735         {
2736                 .procname       = "max_size",
2737                 .data           = &ip_rt_max_size,
2738                 .maxlen         = sizeof(int),
2739                 .mode           = 0644,
2740                 .proc_handler   = proc_dointvec,
2741         },
2742         {
2743                 /*  Deprecated. Use gc_min_interval_ms */
2744 
2745                 .procname       = "gc_min_interval",
2746                 .data           = &ip_rt_gc_min_interval,
2747                 .maxlen         = sizeof(int),
2748                 .mode           = 0644,
2749                 .proc_handler   = proc_dointvec_jiffies,
2750         },
2751         {
2752                 .procname       = "gc_min_interval_ms",
2753                 .data           = &ip_rt_gc_min_interval,
2754                 .maxlen         = sizeof(int),
2755                 .mode           = 0644,
2756                 .proc_handler   = proc_dointvec_ms_jiffies,
2757         },
2758         {
2759                 .procname       = "gc_timeout",
2760                 .data           = &ip_rt_gc_timeout,
2761                 .maxlen         = sizeof(int),
2762                 .mode           = 0644,
2763                 .proc_handler   = proc_dointvec_jiffies,
2764         },
2765         {
2766                 .procname       = "gc_interval",
2767                 .data           = &ip_rt_gc_interval,
2768                 .maxlen         = sizeof(int),
2769                 .mode           = 0644,
2770                 .proc_handler   = proc_dointvec_jiffies,
2771         },
2772         {
2773                 .procname       = "redirect_load",
2774                 .data           = &ip_rt_redirect_load,
2775                 .maxlen         = sizeof(int),
2776                 .mode           = 0644,
2777                 .proc_handler   = proc_dointvec,
2778         },
2779         {
2780                 .procname       = "redirect_number",
2781                 .data           = &ip_rt_redirect_number,
2782                 .maxlen         = sizeof(int),
2783                 .mode           = 0644,
2784                 .proc_handler   = proc_dointvec,
2785         },
2786         {
2787                 .procname       = "redirect_silence",
2788                 .data           = &ip_rt_redirect_silence,
2789                 .maxlen         = sizeof(int),
2790                 .mode           = 0644,
2791                 .proc_handler   = proc_dointvec,
2792         },
2793         {
2794                 .procname       = "error_cost",
2795                 .data           = &ip_rt_error_cost,
2796                 .maxlen         = sizeof(int),
2797                 .mode           = 0644,
2798                 .proc_handler   = proc_dointvec,
2799         },
2800         {
2801                 .procname       = "error_burst",
2802                 .data           = &ip_rt_error_burst,
2803                 .maxlen         = sizeof(int),
2804                 .mode           = 0644,
2805                 .proc_handler   = proc_dointvec,
2806         },
2807         {
2808                 .procname       = "gc_elasticity",
2809                 .data           = &ip_rt_gc_elasticity,
2810                 .maxlen         = sizeof(int),
2811                 .mode           = 0644,
2812                 .proc_handler   = proc_dointvec,
2813         },
2814         {
2815                 .procname       = "mtu_expires",
2816                 .data           = &ip_rt_mtu_expires,
2817                 .maxlen         = sizeof(int),
2818                 .mode           = 0644,
2819                 .proc_handler   = proc_dointvec_jiffies,
2820         },
2821         {
2822                 .procname       = "min_pmtu",
2823                 .data           = &ip_rt_min_pmtu,
2824                 .maxlen         = sizeof(int),
2825                 .mode           = 0644,
2826                 .proc_handler   = proc_dointvec,
2827         },
2828         {
2829                 .procname       = "min_adv_mss",
2830                 .data           = &ip_rt_min_advmss,
2831                 .maxlen         = sizeof(int),
2832                 .mode           = 0644,
2833                 .proc_handler   = proc_dointvec,
2834         },
2835         { }
2836 };
2837 
2838 static struct ctl_table ipv4_route_flush_table[] = {
2839         {
2840                 .procname       = "flush",
2841                 .maxlen         = sizeof(int),
2842                 .mode           = 0200,
2843                 .proc_handler   = ipv4_sysctl_rtcache_flush,
2844         },
2845         { },
2846 };
2847 
2848 static __net_init int sysctl_route_net_init(struct net *net)
2849 {
2850         struct ctl_table *tbl;
2851 
2852         tbl = ipv4_route_flush_table;
2853         if (!net_eq(net, &init_net)) {
2854                 tbl = kmemdup(tbl, sizeof(ipv4_route_flush_table), GFP_KERNEL);
2855                 if (!tbl)
2856                         goto err_dup;
2857 
2858                 /* Don't export sysctls to unprivileged users */
2859                 if (net->user_ns != &init_user_ns)
2860                         tbl[0].procname = NULL;
2861         }
2862         tbl[0].extra1 = net;
2863 
2864         net->ipv4.route_hdr = register_net_sysctl(net, "net/ipv4/route", tbl);
2865         if (!net->ipv4.route_hdr)
2866                 goto err_reg;
2867         return 0;
2868 
2869 err_reg:
2870         if (tbl != ipv4_route_flush_table)
2871                 kfree(tbl);
2872 err_dup:
2873         return -ENOMEM;
2874 }
2875 
2876 static __net_exit void sysctl_route_net_exit(struct net *net)
2877 {
2878         struct ctl_table *tbl;
2879 
2880         tbl = net->ipv4.route_hdr->ctl_table_arg;
2881         unregister_net_sysctl_table(net->ipv4.route_hdr);
2882         BUG_ON(tbl == ipv4_route_flush_table);
2883         kfree(tbl);
2884 }
2885 
2886 static __net_initdata struct pernet_operations sysctl_route_ops = {
2887         .init = sysctl_route_net_init,
2888         .exit = sysctl_route_net_exit,
2889 };
2890 #endif
2891 
2892 static __net_init int rt_genid_init(struct net *net)
2893 {
2894         atomic_set(&net->ipv4.rt_genid, 0);
2895         atomic_set(&net->fnhe_genid, 0);
2896         get_random_bytes(&net->ipv4.dev_addr_genid,
2897                          sizeof(net->ipv4.dev_addr_genid));
2898         return 0;
2899 }
2900 
2901 static __net_initdata struct pernet_operations rt_genid_ops = {
2902         .init = rt_genid_init,
2903 };
2904 
2905 static int __net_init ipv4_inetpeer_init(struct net *net)
2906 {
2907         struct inet_peer_base *bp = kmalloc(sizeof(*bp), GFP_KERNEL);
2908 
2909         if (!bp)
2910                 return -ENOMEM;
2911         inet_peer_base_init(bp);
2912         net->ipv4.peers = bp;
2913         return 0;
2914 }
2915 
2916 static void __net_exit ipv4_inetpeer_exit(struct net *net)
2917 {
2918         struct inet_peer_base *bp = net->ipv4.peers;
2919 
2920         net->ipv4.peers = NULL;
2921         inetpeer_invalidate_tree(bp);
2922         kfree(bp);
2923 }
2924 
2925 static __net_initdata struct pernet_operations ipv4_inetpeer_ops = {
2926         .init   =       ipv4_inetpeer_init,
2927         .exit   =       ipv4_inetpeer_exit,
2928 };
2929 
2930 #ifdef CONFIG_IP_ROUTE_CLASSID
2931 struct ip_rt_acct __percpu *ip_rt_acct __read_mostly;
2932 #endif /* CONFIG_IP_ROUTE_CLASSID */
2933 
2934 int __init ip_rt_init(void)
2935 {
2936         int rc = 0;
2937         int cpu;
2938 
2939         ip_idents = kmalloc(IP_IDENTS_SZ * sizeof(*ip_idents), GFP_KERNEL);
2940         if (!ip_idents)
2941                 panic("IP: failed to allocate ip_idents\n");
2942 
2943         prandom_bytes(ip_idents, IP_IDENTS_SZ * sizeof(*ip_idents));
2944 
2945         ip_tstamps = kcalloc(IP_IDENTS_SZ, sizeof(*ip_tstamps), GFP_KERNEL);
2946         if (!ip_tstamps)
2947                 panic("IP: failed to allocate ip_tstamps\n");
2948 
2949         for_each_possible_cpu(cpu) {
2950                 struct uncached_list *ul = &per_cpu(rt_uncached_list, cpu);
2951 
2952                 INIT_LIST_HEAD(&ul->head);
2953                 spin_lock_init(&ul->lock);
2954         }
2955 #ifdef CONFIG_IP_ROUTE_CLASSID
2956         ip_rt_acct = __alloc_percpu(256 * sizeof(struct ip_rt_acct), __alignof__(struct ip_rt_acct));
2957         if (!ip_rt_acct)
2958                 panic("IP: failed to allocate ip_rt_acct\n");
2959 #endif
2960 
2961         ipv4_dst_ops.kmem_cachep =
2962                 kmem_cache_create("ip_dst_cache", sizeof(struct rtable), 0,
2963                                   SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
2964 
2965         ipv4_dst_blackhole_ops.kmem_cachep = ipv4_dst_ops.kmem_cachep;
2966 
2967         if (dst_entries_init(&ipv4_dst_ops) < 0)
2968                 panic("IP: failed to allocate ipv4_dst_ops counter\n");
2969 
2970         if (dst_entries_init(&ipv4_dst_blackhole_ops) < 0)
2971                 panic("IP: failed to allocate ipv4_dst_blackhole_ops counter\n");
2972 
2973         ipv4_dst_ops.gc_thresh = ~0;
2974         ip_rt_max_size = INT_MAX;
2975 
2976         devinet_init();
2977         ip_fib_init();
2978 
2979         if (ip_rt_proc_init())
2980                 pr_err("Unable to create route proc files\n");
2981 #ifdef CONFIG_XFRM
2982         xfrm_init();
2983         xfrm4_init();
2984 #endif
2985         rtnl_register(PF_INET, RTM_GETROUTE, inet_rtm_getroute, NULL, NULL);
2986 
2987 #ifdef CONFIG_SYSCTL
2988         register_pernet_subsys(&sysctl_route_ops);
2989 #endif
2990         register_pernet_subsys(&rt_genid_ops);
2991         register_pernet_subsys(&ipv4_inetpeer_ops);
2992         return rc;
2993 }
2994 
2995 #ifdef CONFIG_SYSCTL
2996 /*
2997  * We really need to sanitize the damn ipv4 init order, then all
2998  * this nonsense will go away.
2999  */
3000 void __init ip_static_sysctl_init(void)
3001 {
3002         register_net_sysctl(&init_net, "net/ipv4/route", ipv4_route_table);
3003 }
3004 #endif
3005 

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