Version:  2.0.40 2.2.26 2.4.37 3.8 3.9 3.10 3.11 3.12 3.13 3.14 3.15 3.16 3.17 3.18 3.19 4.0 4.1 4.2 4.3 4.4 4.5

Linux/net/ipv4/route.c

  1 /*
  2  * INET         An implementation of the TCP/IP protocol suite for the LINUX
  3  *              operating system.  INET is implemented using the  BSD Socket
  4  *              interface as the means of communication with the user level.
  5  *
  6  *              ROUTE - implementation of the IP router.
  7  *
  8  * Authors:     Ross Biro
  9  *              Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
 10  *              Alan Cox, <gw4pts@gw4pts.ampr.org>
 11  *              Linus Torvalds, <Linus.Torvalds@helsinki.fi>
 12  *              Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
 13  *
 14  * Fixes:
 15  *              Alan Cox        :       Verify area fixes.
 16  *              Alan Cox        :       cli() protects routing changes
 17  *              Rui Oliveira    :       ICMP routing table updates
 18  *              (rco@di.uminho.pt)      Routing table insertion and update
 19  *              Linus Torvalds  :       Rewrote bits to be sensible
 20  *              Alan Cox        :       Added BSD route gw semantics
 21  *              Alan Cox        :       Super /proc >4K
 22  *              Alan Cox        :       MTU in route table
 23  *              Alan Cox        :       MSS actually. Also added the window
 24  *                                      clamper.
 25  *              Sam Lantinga    :       Fixed route matching in rt_del()
 26  *              Alan Cox        :       Routing cache support.
 27  *              Alan Cox        :       Removed compatibility cruft.
 28  *              Alan Cox        :       RTF_REJECT support.
 29  *              Alan Cox        :       TCP irtt support.
 30  *              Jonathan Naylor :       Added Metric support.
 31  *      Miquel van Smoorenburg  :       BSD API fixes.
 32  *      Miquel van Smoorenburg  :       Metrics.
 33  *              Alan Cox        :       Use __u32 properly
 34  *              Alan Cox        :       Aligned routing errors more closely with BSD
 35  *                                      our system is still very different.
 36  *              Alan Cox        :       Faster /proc handling
 37  *      Alexey Kuznetsov        :       Massive rework to support tree based routing,
 38  *                                      routing caches and better behaviour.
 39  *
 40  *              Olaf Erb        :       irtt wasn't being copied right.
 41  *              Bjorn Ekwall    :       Kerneld route support.
 42  *              Alan Cox        :       Multicast fixed (I hope)
 43  *              Pavel Krauz     :       Limited broadcast fixed
 44  *              Mike McLagan    :       Routing by source
 45  *      Alexey Kuznetsov        :       End of old history. Split to fib.c and
 46  *                                      route.c and rewritten from scratch.
 47  *              Andi Kleen      :       Load-limit warning messages.
 48  *      Vitaly E. Lavrov        :       Transparent proxy revived after year coma.
 49  *      Vitaly E. Lavrov        :       Race condition in ip_route_input_slow.
 50  *      Tobias Ringstrom        :       Uninitialized res.type in ip_route_output_slow.
 51  *      Vladimir V. Ivanov      :       IP rule info (flowid) is really useful.
 52  *              Marc Boucher    :       routing by fwmark
 53  *      Robert Olsson           :       Added rt_cache statistics
 54  *      Arnaldo C. Melo         :       Convert proc stuff to seq_file
 55  *      Eric Dumazet            :       hashed spinlocks and rt_check_expire() fixes.
 56  *      Ilia Sotnikov           :       Ignore TOS on PMTUD and Redirect
 57  *      Ilia Sotnikov           :       Removed TOS from hash calculations
 58  *
 59  *              This program is free software; you can redistribute it and/or
 60  *              modify it under the terms of the GNU General Public License
 61  *              as published by the Free Software Foundation; either version
 62  *              2 of the License, or (at your option) any later version.
 63  */
 64 
 65 #define pr_fmt(fmt) "IPv4: " fmt
 66 
 67 #include <linux/module.h>
 68 #include <asm/uaccess.h>
 69 #include <linux/bitops.h>
 70 #include <linux/types.h>
 71 #include <linux/kernel.h>
 72 #include <linux/mm.h>
 73 #include <linux/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 
158 static struct dst_ops ipv4_dst_ops = {
159         .family =               AF_INET,
160         .check =                ipv4_dst_check,
161         .default_advmss =       ipv4_default_advmss,
162         .mtu =                  ipv4_mtu,
163         .cow_metrics =          ipv4_cow_metrics,
164         .destroy =              ipv4_dst_destroy,
165         .negative_advice =      ipv4_negative_advice,
166         .link_failure =         ipv4_link_failure,
167         .update_pmtu =          ip_rt_update_pmtu,
168         .redirect =             ip_do_redirect,
169         .local_out =            __ip_local_out,
170         .neigh_lookup =         ipv4_neigh_lookup,
171 };
172 
173 #define ECN_OR_COST(class)      TC_PRIO_##class
174 
175 const __u8 ip_tos2prio[16] = {
176         TC_PRIO_BESTEFFORT,
177         ECN_OR_COST(BESTEFFORT),
178         TC_PRIO_BESTEFFORT,
179         ECN_OR_COST(BESTEFFORT),
180         TC_PRIO_BULK,
181         ECN_OR_COST(BULK),
182         TC_PRIO_BULK,
183         ECN_OR_COST(BULK),
184         TC_PRIO_INTERACTIVE,
185         ECN_OR_COST(INTERACTIVE),
186         TC_PRIO_INTERACTIVE,
187         ECN_OR_COST(INTERACTIVE),
188         TC_PRIO_INTERACTIVE_BULK,
189         ECN_OR_COST(INTERACTIVE_BULK),
190         TC_PRIO_INTERACTIVE_BULK,
191         ECN_OR_COST(INTERACTIVE_BULK)
192 };
193 EXPORT_SYMBOL(ip_tos2prio);
194 
195 static DEFINE_PER_CPU(struct rt_cache_stat, rt_cache_stat);
196 #define RT_CACHE_STAT_INC(field) raw_cpu_inc(rt_cache_stat.field)
197 
198 #ifdef CONFIG_PROC_FS
199 static void *rt_cache_seq_start(struct seq_file *seq, loff_t *pos)
200 {
201         if (*pos)
202                 return NULL;
203         return SEQ_START_TOKEN;
204 }
205 
206 static void *rt_cache_seq_next(struct seq_file *seq, void *v, loff_t *pos)
207 {
208         ++*pos;
209         return NULL;
210 }
211 
212 static void rt_cache_seq_stop(struct seq_file *seq, void *v)
213 {
214 }
215 
216 static int rt_cache_seq_show(struct seq_file *seq, void *v)
217 {
218         if (v == SEQ_START_TOKEN)
219                 seq_printf(seq, "%-127s\n",
220                            "Iface\tDestination\tGateway \tFlags\t\tRefCnt\tUse\t"
221                            "Metric\tSource\t\tMTU\tWindow\tIRTT\tTOS\tHHRef\t"
222                            "HHUptod\tSpecDst");
223         return 0;
224 }
225 
226 static const struct seq_operations rt_cache_seq_ops = {
227         .start  = rt_cache_seq_start,
228         .next   = rt_cache_seq_next,
229         .stop   = rt_cache_seq_stop,
230         .show   = rt_cache_seq_show,
231 };
232 
233 static int rt_cache_seq_open(struct inode *inode, struct file *file)
234 {
235         return seq_open(file, &rt_cache_seq_ops);
236 }
237 
238 static const struct file_operations rt_cache_seq_fops = {
239         .owner   = THIS_MODULE,
240         .open    = rt_cache_seq_open,
241         .read    = seq_read,
242         .llseek  = seq_lseek,
243         .release = seq_release,
244 };
245 
246 
247 static void *rt_cpu_seq_start(struct seq_file *seq, loff_t *pos)
248 {
249         int cpu;
250 
251         if (*pos == 0)
252                 return SEQ_START_TOKEN;
253 
254         for (cpu = *pos-1; cpu < nr_cpu_ids; ++cpu) {
255                 if (!cpu_possible(cpu))
256                         continue;
257                 *pos = cpu+1;
258                 return &per_cpu(rt_cache_stat, cpu);
259         }
260         return NULL;
261 }
262 
263 static void *rt_cpu_seq_next(struct seq_file *seq, void *v, loff_t *pos)
264 {
265         int cpu;
266 
267         for (cpu = *pos; cpu < nr_cpu_ids; ++cpu) {
268                 if (!cpu_possible(cpu))
269                         continue;
270                 *pos = cpu+1;
271                 return &per_cpu(rt_cache_stat, cpu);
272         }
273         return NULL;
274 
275 }
276 
277 static void rt_cpu_seq_stop(struct seq_file *seq, void *v)
278 {
279 
280 }
281 
282 static int rt_cpu_seq_show(struct seq_file *seq, void *v)
283 {
284         struct rt_cache_stat *st = v;
285 
286         if (v == SEQ_START_TOKEN) {
287                 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");
288                 return 0;
289         }
290 
291         seq_printf(seq,"%08x  %08x %08x %08x %08x %08x %08x %08x "
292                    " %08x %08x %08x %08x %08x %08x %08x %08x %08x \n",
293                    dst_entries_get_slow(&ipv4_dst_ops),
294                    0, /* st->in_hit */
295                    st->in_slow_tot,
296                    st->in_slow_mc,
297                    st->in_no_route,
298                    st->in_brd,
299                    st->in_martian_dst,
300                    st->in_martian_src,
301 
302                    0, /* st->out_hit */
303                    st->out_slow_tot,
304                    st->out_slow_mc,
305 
306                    0, /* st->gc_total */
307                    0, /* st->gc_ignored */
308                    0, /* st->gc_goal_miss */
309                    0, /* st->gc_dst_overflow */
310                    0, /* st->in_hlist_search */
311                    0  /* st->out_hlist_search */
312                 );
313         return 0;
314 }
315 
316 static const struct seq_operations rt_cpu_seq_ops = {
317         .start  = rt_cpu_seq_start,
318         .next   = rt_cpu_seq_next,
319         .stop   = rt_cpu_seq_stop,
320         .show   = rt_cpu_seq_show,
321 };
322 
323 
324 static int rt_cpu_seq_open(struct inode *inode, struct file *file)
325 {
326         return seq_open(file, &rt_cpu_seq_ops);
327 }
328 
329 static const struct file_operations rt_cpu_seq_fops = {
330         .owner   = THIS_MODULE,
331         .open    = rt_cpu_seq_open,
332         .read    = seq_read,
333         .llseek  = seq_lseek,
334         .release = seq_release,
335 };
336 
337 #ifdef CONFIG_IP_ROUTE_CLASSID
338 static int rt_acct_proc_show(struct seq_file *m, void *v)
339 {
340         struct ip_rt_acct *dst, *src;
341         unsigned int i, j;
342 
343         dst = kcalloc(256, sizeof(struct ip_rt_acct), GFP_KERNEL);
344         if (!dst)
345                 return -ENOMEM;
346 
347         for_each_possible_cpu(i) {
348                 src = (struct ip_rt_acct *)per_cpu_ptr(ip_rt_acct, i);
349                 for (j = 0; j < 256; j++) {
350                         dst[j].o_bytes   += src[j].o_bytes;
351                         dst[j].o_packets += src[j].o_packets;
352                         dst[j].i_bytes   += src[j].i_bytes;
353                         dst[j].i_packets += src[j].i_packets;
354                 }
355         }
356 
357         seq_write(m, dst, 256 * sizeof(struct ip_rt_acct));
358         kfree(dst);
359         return 0;
360 }
361 
362 static int rt_acct_proc_open(struct inode *inode, struct file *file)
363 {
364         return single_open(file, rt_acct_proc_show, NULL);
365 }
366 
367 static const struct file_operations rt_acct_proc_fops = {
368         .owner          = THIS_MODULE,
369         .open           = rt_acct_proc_open,
370         .read           = seq_read,
371         .llseek         = seq_lseek,
372         .release        = single_release,
373 };
374 #endif
375 
376 static int __net_init ip_rt_do_proc_init(struct net *net)
377 {
378         struct proc_dir_entry *pde;
379 
380         pde = proc_create("rt_cache", S_IRUGO, net->proc_net,
381                           &rt_cache_seq_fops);
382         if (!pde)
383                 goto err1;
384 
385         pde = proc_create("rt_cache", S_IRUGO,
386                           net->proc_net_stat, &rt_cpu_seq_fops);
387         if (!pde)
388                 goto err2;
389 
390 #ifdef CONFIG_IP_ROUTE_CLASSID
391         pde = proc_create("rt_acct", 0, net->proc_net, &rt_acct_proc_fops);
392         if (!pde)
393                 goto err3;
394 #endif
395         return 0;
396 
397 #ifdef CONFIG_IP_ROUTE_CLASSID
398 err3:
399         remove_proc_entry("rt_cache", net->proc_net_stat);
400 #endif
401 err2:
402         remove_proc_entry("rt_cache", net->proc_net);
403 err1:
404         return -ENOMEM;
405 }
406 
407 static void __net_exit ip_rt_do_proc_exit(struct net *net)
408 {
409         remove_proc_entry("rt_cache", net->proc_net_stat);
410         remove_proc_entry("rt_cache", net->proc_net);
411 #ifdef CONFIG_IP_ROUTE_CLASSID
412         remove_proc_entry("rt_acct", net->proc_net);
413 #endif
414 }
415 
416 static struct pernet_operations ip_rt_proc_ops __net_initdata =  {
417         .init = ip_rt_do_proc_init,
418         .exit = ip_rt_do_proc_exit,
419 };
420 
421 static int __init ip_rt_proc_init(void)
422 {
423         return register_pernet_subsys(&ip_rt_proc_ops);
424 }
425 
426 #else
427 static inline int ip_rt_proc_init(void)
428 {
429         return 0;
430 }
431 #endif /* CONFIG_PROC_FS */
432 
433 static inline bool rt_is_expired(const struct rtable *rth)
434 {
435         return rth->rt_genid != rt_genid_ipv4(dev_net(rth->dst.dev));
436 }
437 
438 void rt_cache_flush(struct net *net)
439 {
440         rt_genid_bump_ipv4(net);
441 }
442 
443 static struct neighbour *ipv4_neigh_lookup(const struct dst_entry *dst,
444                                            struct sk_buff *skb,
445                                            const void *daddr)
446 {
447         struct net_device *dev = dst->dev;
448         const __be32 *pkey = daddr;
449         const struct rtable *rt;
450         struct neighbour *n;
451 
452         rt = (const struct rtable *) dst;
453         if (rt->rt_gateway)
454                 pkey = (const __be32 *) &rt->rt_gateway;
455         else if (skb)
456                 pkey = &ip_hdr(skb)->daddr;
457 
458         n = __ipv4_neigh_lookup(dev, *(__force u32 *)pkey);
459         if (n)
460                 return n;
461         return neigh_create(&arp_tbl, pkey, dev);
462 }
463 
464 #define IP_IDENTS_SZ 2048u
465 
466 static atomic_t *ip_idents __read_mostly;
467 static u32 *ip_tstamps __read_mostly;
468 
469 /* In order to protect privacy, we add a perturbation to identifiers
470  * if one generator is seldom used. This makes hard for an attacker
471  * to infer how many packets were sent between two points in time.
472  */
473 u32 ip_idents_reserve(u32 hash, int segs)
474 {
475         u32 *p_tstamp = ip_tstamps + hash % IP_IDENTS_SZ;
476         atomic_t *p_id = ip_idents + hash % IP_IDENTS_SZ;
477         u32 old = ACCESS_ONCE(*p_tstamp);
478         u32 now = (u32)jiffies;
479         u32 delta = 0;
480 
481         if (old != now && cmpxchg(p_tstamp, old, now) == old)
482                 delta = prandom_u32_max(now - old);
483 
484         return atomic_add_return(segs + delta, p_id) - segs;
485 }
486 EXPORT_SYMBOL(ip_idents_reserve);
487 
488 void __ip_select_ident(struct net *net, struct iphdr *iph, int segs)
489 {
490         static u32 ip_idents_hashrnd __read_mostly;
491         u32 hash, id;
492 
493         net_get_random_once(&ip_idents_hashrnd, sizeof(ip_idents_hashrnd));
494 
495         hash = jhash_3words((__force u32)iph->daddr,
496                             (__force u32)iph->saddr,
497                             iph->protocol ^ net_hash_mix(net),
498                             ip_idents_hashrnd);
499         id = ip_idents_reserve(hash, segs);
500         iph->id = htons(id);
501 }
502 EXPORT_SYMBOL(__ip_select_ident);
503 
504 static void __build_flow_key(struct flowi4 *fl4, const struct sock *sk,
505                              const struct iphdr *iph,
506                              int oif, u8 tos,
507                              u8 prot, u32 mark, int flow_flags)
508 {
509         if (sk) {
510                 const struct inet_sock *inet = inet_sk(sk);
511 
512                 oif = sk->sk_bound_dev_if;
513                 mark = sk->sk_mark;
514                 tos = RT_CONN_FLAGS(sk);
515                 prot = inet->hdrincl ? IPPROTO_RAW : sk->sk_protocol;
516         }
517         flowi4_init_output(fl4, oif, mark, tos,
518                            RT_SCOPE_UNIVERSE, prot,
519                            flow_flags,
520                            iph->daddr, iph->saddr, 0, 0);
521 }
522 
523 static void build_skb_flow_key(struct flowi4 *fl4, const struct sk_buff *skb,
524                                const struct sock *sk)
525 {
526         const struct iphdr *iph = ip_hdr(skb);
527         int oif = skb->dev->ifindex;
528         u8 tos = RT_TOS(iph->tos);
529         u8 prot = iph->protocol;
530         u32 mark = skb->mark;
531 
532         __build_flow_key(fl4, sk, iph, oif, tos, prot, mark, 0);
533 }
534 
535 static void build_sk_flow_key(struct flowi4 *fl4, const struct sock *sk)
536 {
537         const struct inet_sock *inet = inet_sk(sk);
538         const struct ip_options_rcu *inet_opt;
539         __be32 daddr = inet->inet_daddr;
540 
541         rcu_read_lock();
542         inet_opt = rcu_dereference(inet->inet_opt);
543         if (inet_opt && inet_opt->opt.srr)
544                 daddr = inet_opt->opt.faddr;
545         flowi4_init_output(fl4, sk->sk_bound_dev_if, sk->sk_mark,
546                            RT_CONN_FLAGS(sk), RT_SCOPE_UNIVERSE,
547                            inet->hdrincl ? IPPROTO_RAW : sk->sk_protocol,
548                            inet_sk_flowi_flags(sk),
549                            daddr, inet->inet_saddr, 0, 0);
550         rcu_read_unlock();
551 }
552 
553 static void ip_rt_build_flow_key(struct flowi4 *fl4, const struct sock *sk,
554                                  const struct sk_buff *skb)
555 {
556         if (skb)
557                 build_skb_flow_key(fl4, skb, sk);
558         else
559                 build_sk_flow_key(fl4, sk);
560 }
561 
562 static inline void rt_free(struct rtable *rt)
563 {
564         call_rcu(&rt->dst.rcu_head, dst_rcu_free);
565 }
566 
567 static DEFINE_SPINLOCK(fnhe_lock);
568 
569 static void fnhe_flush_routes(struct fib_nh_exception *fnhe)
570 {
571         struct rtable *rt;
572 
573         rt = rcu_dereference(fnhe->fnhe_rth_input);
574         if (rt) {
575                 RCU_INIT_POINTER(fnhe->fnhe_rth_input, NULL);
576                 rt_free(rt);
577         }
578         rt = rcu_dereference(fnhe->fnhe_rth_output);
579         if (rt) {
580                 RCU_INIT_POINTER(fnhe->fnhe_rth_output, NULL);
581                 rt_free(rt);
582         }
583 }
584 
585 static struct fib_nh_exception *fnhe_oldest(struct fnhe_hash_bucket *hash)
586 {
587         struct fib_nh_exception *fnhe, *oldest;
588 
589         oldest = rcu_dereference(hash->chain);
590         for (fnhe = rcu_dereference(oldest->fnhe_next); fnhe;
591              fnhe = rcu_dereference(fnhe->fnhe_next)) {
592                 if (time_before(fnhe->fnhe_stamp, oldest->fnhe_stamp))
593                         oldest = fnhe;
594         }
595         fnhe_flush_routes(oldest);
596         return oldest;
597 }
598 
599 static inline u32 fnhe_hashfun(__be32 daddr)
600 {
601         static u32 fnhe_hashrnd __read_mostly;
602         u32 hval;
603 
604         net_get_random_once(&fnhe_hashrnd, sizeof(fnhe_hashrnd));
605         hval = jhash_1word((__force u32) daddr, fnhe_hashrnd);
606         return hash_32(hval, FNHE_HASH_SHIFT);
607 }
608 
609 static void fill_route_from_fnhe(struct rtable *rt, struct fib_nh_exception *fnhe)
610 {
611         rt->rt_pmtu = fnhe->fnhe_pmtu;
612         rt->dst.expires = fnhe->fnhe_expires;
613 
614         if (fnhe->fnhe_gw) {
615                 rt->rt_flags |= RTCF_REDIRECTED;
616                 rt->rt_gateway = fnhe->fnhe_gw;
617                 rt->rt_uses_gateway = 1;
618         }
619 }
620 
621 static void update_or_create_fnhe(struct fib_nh *nh, __be32 daddr, __be32 gw,
622                                   u32 pmtu, unsigned long expires)
623 {
624         struct fnhe_hash_bucket *hash;
625         struct fib_nh_exception *fnhe;
626         struct rtable *rt;
627         unsigned int i;
628         int depth;
629         u32 hval = fnhe_hashfun(daddr);
630 
631         spin_lock_bh(&fnhe_lock);
632 
633         hash = rcu_dereference(nh->nh_exceptions);
634         if (!hash) {
635                 hash = kzalloc(FNHE_HASH_SIZE * sizeof(*hash), GFP_ATOMIC);
636                 if (!hash)
637                         goto out_unlock;
638                 rcu_assign_pointer(nh->nh_exceptions, hash);
639         }
640 
641         hash += hval;
642 
643         depth = 0;
644         for (fnhe = rcu_dereference(hash->chain); fnhe;
645              fnhe = rcu_dereference(fnhe->fnhe_next)) {
646                 if (fnhe->fnhe_daddr == daddr)
647                         break;
648                 depth++;
649         }
650 
651         if (fnhe) {
652                 if (gw)
653                         fnhe->fnhe_gw = gw;
654                 if (pmtu) {
655                         fnhe->fnhe_pmtu = pmtu;
656                         fnhe->fnhe_expires = max(1UL, expires);
657                 }
658                 /* Update all cached dsts too */
659                 rt = rcu_dereference(fnhe->fnhe_rth_input);
660                 if (rt)
661                         fill_route_from_fnhe(rt, fnhe);
662                 rt = rcu_dereference(fnhe->fnhe_rth_output);
663                 if (rt)
664                         fill_route_from_fnhe(rt, fnhe);
665         } else {
666                 if (depth > FNHE_RECLAIM_DEPTH)
667                         fnhe = fnhe_oldest(hash);
668                 else {
669                         fnhe = kzalloc(sizeof(*fnhe), GFP_ATOMIC);
670                         if (!fnhe)
671                                 goto out_unlock;
672 
673                         fnhe->fnhe_next = hash->chain;
674                         rcu_assign_pointer(hash->chain, fnhe);
675                 }
676                 fnhe->fnhe_genid = fnhe_genid(dev_net(nh->nh_dev));
677                 fnhe->fnhe_daddr = daddr;
678                 fnhe->fnhe_gw = gw;
679                 fnhe->fnhe_pmtu = pmtu;
680                 fnhe->fnhe_expires = expires;
681 
682                 /* Exception created; mark the cached routes for the nexthop
683                  * stale, so anyone caching it rechecks if this exception
684                  * applies to them.
685                  */
686                 rt = rcu_dereference(nh->nh_rth_input);
687                 if (rt)
688                         rt->dst.obsolete = DST_OBSOLETE_KILL;
689 
690                 for_each_possible_cpu(i) {
691                         struct rtable __rcu **prt;
692                         prt = per_cpu_ptr(nh->nh_pcpu_rth_output, i);
693                         rt = rcu_dereference(*prt);
694                         if (rt)
695                                 rt->dst.obsolete = DST_OBSOLETE_KILL;
696                 }
697         }
698 
699         fnhe->fnhe_stamp = jiffies;
700 
701 out_unlock:
702         spin_unlock_bh(&fnhe_lock);
703 }
704 
705 static void __ip_do_redirect(struct rtable *rt, struct sk_buff *skb, struct flowi4 *fl4,
706                              bool kill_route)
707 {
708         __be32 new_gw = icmp_hdr(skb)->un.gateway;
709         __be32 old_gw = ip_hdr(skb)->saddr;
710         struct net_device *dev = skb->dev;
711         struct in_device *in_dev;
712         struct fib_result res;
713         struct neighbour *n;
714         struct net *net;
715 
716         switch (icmp_hdr(skb)->code & 7) {
717         case ICMP_REDIR_NET:
718         case ICMP_REDIR_NETTOS:
719         case ICMP_REDIR_HOST:
720         case ICMP_REDIR_HOSTTOS:
721                 break;
722 
723         default:
724                 return;
725         }
726 
727         if (rt->rt_gateway != old_gw)
728                 return;
729 
730         in_dev = __in_dev_get_rcu(dev);
731         if (!in_dev)
732                 return;
733 
734         net = dev_net(dev);
735         if (new_gw == old_gw || !IN_DEV_RX_REDIRECTS(in_dev) ||
736             ipv4_is_multicast(new_gw) || ipv4_is_lbcast(new_gw) ||
737             ipv4_is_zeronet(new_gw))
738                 goto reject_redirect;
739 
740         if (!IN_DEV_SHARED_MEDIA(in_dev)) {
741                 if (!inet_addr_onlink(in_dev, new_gw, old_gw))
742                         goto reject_redirect;
743                 if (IN_DEV_SEC_REDIRECTS(in_dev) && ip_fib_check_default(new_gw, dev))
744                         goto reject_redirect;
745         } else {
746                 if (inet_addr_type(net, new_gw) != RTN_UNICAST)
747                         goto reject_redirect;
748         }
749 
750         n = ipv4_neigh_lookup(&rt->dst, NULL, &new_gw);
751         if (!IS_ERR(n)) {
752                 if (!(n->nud_state & NUD_VALID)) {
753                         neigh_event_send(n, NULL);
754                 } else {
755                         if (fib_lookup(net, fl4, &res, 0) == 0) {
756                                 struct fib_nh *nh = &FIB_RES_NH(res);
757 
758                                 update_or_create_fnhe(nh, fl4->daddr, new_gw,
759                                                 0, jiffies + ip_rt_gc_timeout);
760                         }
761                         if (kill_route)
762                                 rt->dst.obsolete = DST_OBSOLETE_KILL;
763                         call_netevent_notifiers(NETEVENT_NEIGH_UPDATE, n);
764                 }
765                 neigh_release(n);
766         }
767         return;
768 
769 reject_redirect:
770 #ifdef CONFIG_IP_ROUTE_VERBOSE
771         if (IN_DEV_LOG_MARTIANS(in_dev)) {
772                 const struct iphdr *iph = (const struct iphdr *) skb->data;
773                 __be32 daddr = iph->daddr;
774                 __be32 saddr = iph->saddr;
775 
776                 net_info_ratelimited("Redirect from %pI4 on %s about %pI4 ignored\n"
777                                      "  Advised path = %pI4 -> %pI4\n",
778                                      &old_gw, dev->name, &new_gw,
779                                      &saddr, &daddr);
780         }
781 #endif
782         ;
783 }
784 
785 static void ip_do_redirect(struct dst_entry *dst, struct sock *sk, struct sk_buff *skb)
786 {
787         struct rtable *rt;
788         struct flowi4 fl4;
789         const struct iphdr *iph = (const struct iphdr *) skb->data;
790         int oif = skb->dev->ifindex;
791         u8 tos = RT_TOS(iph->tos);
792         u8 prot = iph->protocol;
793         u32 mark = skb->mark;
794 
795         rt = (struct rtable *) dst;
796 
797         __build_flow_key(&fl4, sk, iph, oif, tos, prot, mark, 0);
798         __ip_do_redirect(rt, skb, &fl4, true);
799 }
800 
801 static struct dst_entry *ipv4_negative_advice(struct dst_entry *dst)
802 {
803         struct rtable *rt = (struct rtable *)dst;
804         struct dst_entry *ret = dst;
805 
806         if (rt) {
807                 if (dst->obsolete > 0) {
808                         ip_rt_put(rt);
809                         ret = NULL;
810                 } else if ((rt->rt_flags & RTCF_REDIRECTED) ||
811                            rt->dst.expires) {
812                         ip_rt_put(rt);
813                         ret = NULL;
814                 }
815         }
816         return ret;
817 }
818 
819 /*
820  * Algorithm:
821  *      1. The first ip_rt_redirect_number redirects are sent
822  *         with exponential backoff, then we stop sending them at all,
823  *         assuming that the host ignores our redirects.
824  *      2. If we did not see packets requiring redirects
825  *         during ip_rt_redirect_silence, we assume that the host
826  *         forgot redirected route and start to send redirects again.
827  *
828  * This algorithm is much cheaper and more intelligent than dumb load limiting
829  * in icmp.c.
830  *
831  * NOTE. Do not forget to inhibit load limiting for redirects (redundant)
832  * and "frag. need" (breaks PMTU discovery) in icmp.c.
833  */
834 
835 void ip_rt_send_redirect(struct sk_buff *skb)
836 {
837         struct rtable *rt = skb_rtable(skb);
838         struct in_device *in_dev;
839         struct inet_peer *peer;
840         struct net *net;
841         int log_martians;
842         int vif;
843 
844         rcu_read_lock();
845         in_dev = __in_dev_get_rcu(rt->dst.dev);
846         if (!in_dev || !IN_DEV_TX_REDIRECTS(in_dev)) {
847                 rcu_read_unlock();
848                 return;
849         }
850         log_martians = IN_DEV_LOG_MARTIANS(in_dev);
851         vif = l3mdev_master_ifindex_rcu(rt->dst.dev);
852         rcu_read_unlock();
853 
854         net = dev_net(rt->dst.dev);
855         peer = inet_getpeer_v4(net->ipv4.peers, ip_hdr(skb)->saddr, vif, 1);
856         if (!peer) {
857                 icmp_send(skb, ICMP_REDIRECT, ICMP_REDIR_HOST,
858                           rt_nexthop(rt, ip_hdr(skb)->daddr));
859                 return;
860         }
861 
862         /* No redirected packets during ip_rt_redirect_silence;
863          * reset the algorithm.
864          */
865         if (time_after(jiffies, peer->rate_last + ip_rt_redirect_silence))
866                 peer->rate_tokens = 0;
867 
868         /* Too many ignored redirects; do not send anything
869          * set dst.rate_last to the last seen redirected packet.
870          */
871         if (peer->rate_tokens >= ip_rt_redirect_number) {
872                 peer->rate_last = jiffies;
873                 goto out_put_peer;
874         }
875 
876         /* Check for load limit; set rate_last to the latest sent
877          * redirect.
878          */
879         if (peer->rate_tokens == 0 ||
880             time_after(jiffies,
881                        (peer->rate_last +
882                         (ip_rt_redirect_load << peer->rate_tokens)))) {
883                 __be32 gw = rt_nexthop(rt, ip_hdr(skb)->daddr);
884 
885                 icmp_send(skb, ICMP_REDIRECT, ICMP_REDIR_HOST, gw);
886                 peer->rate_last = jiffies;
887                 ++peer->rate_tokens;
888 #ifdef CONFIG_IP_ROUTE_VERBOSE
889                 if (log_martians &&
890                     peer->rate_tokens == ip_rt_redirect_number)
891                         net_warn_ratelimited("host %pI4/if%d ignores redirects for %pI4 to %pI4\n",
892                                              &ip_hdr(skb)->saddr, inet_iif(skb),
893                                              &ip_hdr(skb)->daddr, &gw);
894 #endif
895         }
896 out_put_peer:
897         inet_putpeer(peer);
898 }
899 
900 static int ip_error(struct sk_buff *skb)
901 {
902         struct in_device *in_dev = __in_dev_get_rcu(skb->dev);
903         struct rtable *rt = skb_rtable(skb);
904         struct inet_peer *peer;
905         unsigned long now;
906         struct net *net;
907         bool send;
908         int code;
909 
910         /* IP on this device is disabled. */
911         if (!in_dev)
912                 goto out;
913 
914         net = dev_net(rt->dst.dev);
915         if (!IN_DEV_FORWARD(in_dev)) {
916                 switch (rt->dst.error) {
917                 case EHOSTUNREACH:
918                         IP_INC_STATS_BH(net, IPSTATS_MIB_INADDRERRORS);
919                         break;
920 
921                 case ENETUNREACH:
922                         IP_INC_STATS_BH(net, IPSTATS_MIB_INNOROUTES);
923                         break;
924                 }
925                 goto out;
926         }
927 
928         switch (rt->dst.error) {
929         case EINVAL:
930         default:
931                 goto out;
932         case EHOSTUNREACH:
933                 code = ICMP_HOST_UNREACH;
934                 break;
935         case ENETUNREACH:
936                 code = ICMP_NET_UNREACH;
937                 IP_INC_STATS_BH(net, IPSTATS_MIB_INNOROUTES);
938                 break;
939         case EACCES:
940                 code = ICMP_PKT_FILTERED;
941                 break;
942         }
943 
944         peer = inet_getpeer_v4(net->ipv4.peers, ip_hdr(skb)->saddr,
945                                l3mdev_master_ifindex(skb->dev), 1);
946 
947         send = true;
948         if (peer) {
949                 now = jiffies;
950                 peer->rate_tokens += now - peer->rate_last;
951                 if (peer->rate_tokens > ip_rt_error_burst)
952                         peer->rate_tokens = ip_rt_error_burst;
953                 peer->rate_last = now;
954                 if (peer->rate_tokens >= ip_rt_error_cost)
955                         peer->rate_tokens -= ip_rt_error_cost;
956                 else
957                         send = false;
958                 inet_putpeer(peer);
959         }
960         if (send)
961                 icmp_send(skb, ICMP_DEST_UNREACH, code, 0);
962 
963 out:    kfree_skb(skb);
964         return 0;
965 }
966 
967 static void __ip_rt_update_pmtu(struct rtable *rt, struct flowi4 *fl4, u32 mtu)
968 {
969         struct dst_entry *dst = &rt->dst;
970         struct fib_result res;
971 
972         if (dst_metric_locked(dst, RTAX_MTU))
973                 return;
974 
975         if (ipv4_mtu(dst) < mtu)
976                 return;
977 
978         if (mtu < ip_rt_min_pmtu)
979                 mtu = ip_rt_min_pmtu;
980 
981         if (rt->rt_pmtu == mtu &&
982             time_before(jiffies, dst->expires - ip_rt_mtu_expires / 2))
983                 return;
984 
985         rcu_read_lock();
986         if (fib_lookup(dev_net(dst->dev), fl4, &res, 0) == 0) {
987                 struct fib_nh *nh = &FIB_RES_NH(res);
988 
989                 update_or_create_fnhe(nh, fl4->daddr, 0, mtu,
990                                       jiffies + ip_rt_mtu_expires);
991         }
992         rcu_read_unlock();
993 }
994 
995 static void ip_rt_update_pmtu(struct dst_entry *dst, struct sock *sk,
996                               struct sk_buff *skb, u32 mtu)
997 {
998         struct rtable *rt = (struct rtable *) dst;
999         struct flowi4 fl4;
1000 
1001         ip_rt_build_flow_key(&fl4, sk, skb);
1002         __ip_rt_update_pmtu(rt, &fl4, mtu);
1003 }
1004 
1005 void ipv4_update_pmtu(struct sk_buff *skb, struct net *net, u32 mtu,
1006                       int oif, u32 mark, u8 protocol, int flow_flags)
1007 {
1008         const struct iphdr *iph = (const struct iphdr *) skb->data;
1009         struct flowi4 fl4;
1010         struct rtable *rt;
1011 
1012         if (!mark)
1013                 mark = IP4_REPLY_MARK(net, skb->mark);
1014 
1015         __build_flow_key(&fl4, NULL, iph, oif,
1016                          RT_TOS(iph->tos), protocol, mark, flow_flags);
1017         rt = __ip_route_output_key(net, &fl4);
1018         if (!IS_ERR(rt)) {
1019                 __ip_rt_update_pmtu(rt, &fl4, mtu);
1020                 ip_rt_put(rt);
1021         }
1022 }
1023 EXPORT_SYMBOL_GPL(ipv4_update_pmtu);
1024 
1025 static void __ipv4_sk_update_pmtu(struct sk_buff *skb, struct sock *sk, u32 mtu)
1026 {
1027         const struct iphdr *iph = (const struct iphdr *) skb->data;
1028         struct flowi4 fl4;
1029         struct rtable *rt;
1030 
1031         __build_flow_key(&fl4, sk, iph, 0, 0, 0, 0, 0);
1032 
1033         if (!fl4.flowi4_mark)
1034                 fl4.flowi4_mark = IP4_REPLY_MARK(sock_net(sk), skb->mark);
1035 
1036         rt = __ip_route_output_key(sock_net(sk), &fl4);
1037         if (!IS_ERR(rt)) {
1038                 __ip_rt_update_pmtu(rt, &fl4, mtu);
1039                 ip_rt_put(rt);
1040         }
1041 }
1042 
1043 void ipv4_sk_update_pmtu(struct sk_buff *skb, struct sock *sk, u32 mtu)
1044 {
1045         const struct iphdr *iph = (const struct iphdr *) skb->data;
1046         struct flowi4 fl4;
1047         struct rtable *rt;
1048         struct dst_entry *odst = NULL;
1049         bool new = false;
1050 
1051         bh_lock_sock(sk);
1052 
1053         if (!ip_sk_accept_pmtu(sk))
1054                 goto out;
1055 
1056         odst = sk_dst_get(sk);
1057 
1058         if (sock_owned_by_user(sk) || !odst) {
1059                 __ipv4_sk_update_pmtu(skb, sk, mtu);
1060                 goto out;
1061         }
1062 
1063         __build_flow_key(&fl4, sk, iph, 0, 0, 0, 0, 0);
1064 
1065         rt = (struct rtable *)odst;
1066         if (odst->obsolete && !odst->ops->check(odst, 0)) {
1067                 rt = ip_route_output_flow(sock_net(sk), &fl4, sk);
1068                 if (IS_ERR(rt))
1069                         goto out;
1070 
1071                 new = true;
1072         }
1073 
1074         __ip_rt_update_pmtu((struct rtable *) rt->dst.path, &fl4, mtu);
1075 
1076         if (!dst_check(&rt->dst, 0)) {
1077                 if (new)
1078                         dst_release(&rt->dst);
1079 
1080                 rt = ip_route_output_flow(sock_net(sk), &fl4, sk);
1081                 if (IS_ERR(rt))
1082                         goto out;
1083 
1084                 new = true;
1085         }
1086 
1087         if (new)
1088                 sk_dst_set(sk, &rt->dst);
1089 
1090 out:
1091         bh_unlock_sock(sk);
1092         dst_release(odst);
1093 }
1094 EXPORT_SYMBOL_GPL(ipv4_sk_update_pmtu);
1095 
1096 void ipv4_redirect(struct sk_buff *skb, struct net *net,
1097                    int oif, u32 mark, u8 protocol, int flow_flags)
1098 {
1099         const struct iphdr *iph = (const struct iphdr *) skb->data;
1100         struct flowi4 fl4;
1101         struct rtable *rt;
1102 
1103         __build_flow_key(&fl4, NULL, iph, oif,
1104                          RT_TOS(iph->tos), protocol, mark, flow_flags);
1105         rt = __ip_route_output_key(net, &fl4);
1106         if (!IS_ERR(rt)) {
1107                 __ip_do_redirect(rt, skb, &fl4, false);
1108                 ip_rt_put(rt);
1109         }
1110 }
1111 EXPORT_SYMBOL_GPL(ipv4_redirect);
1112 
1113 void ipv4_sk_redirect(struct sk_buff *skb, struct sock *sk)
1114 {
1115         const struct iphdr *iph = (const struct iphdr *) skb->data;
1116         struct flowi4 fl4;
1117         struct rtable *rt;
1118 
1119         __build_flow_key(&fl4, sk, iph, 0, 0, 0, 0, 0);
1120         rt = __ip_route_output_key(sock_net(sk), &fl4);
1121         if (!IS_ERR(rt)) {
1122                 __ip_do_redirect(rt, skb, &fl4, false);
1123                 ip_rt_put(rt);
1124         }
1125 }
1126 EXPORT_SYMBOL_GPL(ipv4_sk_redirect);
1127 
1128 static struct dst_entry *ipv4_dst_check(struct dst_entry *dst, u32 cookie)
1129 {
1130         struct rtable *rt = (struct rtable *) dst;
1131 
1132         /* All IPV4 dsts are created with ->obsolete set to the value
1133          * DST_OBSOLETE_FORCE_CHK which forces validation calls down
1134          * into this function always.
1135          *
1136          * When a PMTU/redirect information update invalidates a route,
1137          * this is indicated by setting obsolete to DST_OBSOLETE_KILL or
1138          * DST_OBSOLETE_DEAD by dst_free().
1139          */
1140         if (dst->obsolete != DST_OBSOLETE_FORCE_CHK || rt_is_expired(rt))
1141                 return NULL;
1142         return dst;
1143 }
1144 
1145 static void ipv4_link_failure(struct sk_buff *skb)
1146 {
1147         struct rtable *rt;
1148 
1149         icmp_send(skb, ICMP_DEST_UNREACH, ICMP_HOST_UNREACH, 0);
1150 
1151         rt = skb_rtable(skb);
1152         if (rt)
1153                 dst_set_expires(&rt->dst, 0);
1154 }
1155 
1156 static int ip_rt_bug(struct net *net, struct sock *sk, struct sk_buff *skb)
1157 {
1158         pr_debug("%s: %pI4 -> %pI4, %s\n",
1159                  __func__, &ip_hdr(skb)->saddr, &ip_hdr(skb)->daddr,
1160                  skb->dev ? skb->dev->name : "?");
1161         kfree_skb(skb);
1162         WARN_ON(1);
1163         return 0;
1164 }
1165 
1166 /*
1167    We do not cache source address of outgoing interface,
1168    because it is used only by IP RR, TS and SRR options,
1169    so that it out of fast path.
1170 
1171    BTW remember: "addr" is allowed to be not aligned
1172    in IP options!
1173  */
1174 
1175 void ip_rt_get_source(u8 *addr, struct sk_buff *skb, struct rtable *rt)
1176 {
1177         __be32 src;
1178 
1179         if (rt_is_output_route(rt))
1180                 src = ip_hdr(skb)->saddr;
1181         else {
1182                 struct fib_result res;
1183                 struct flowi4 fl4;
1184                 struct iphdr *iph;
1185 
1186                 iph = ip_hdr(skb);
1187 
1188                 memset(&fl4, 0, sizeof(fl4));
1189                 fl4.daddr = iph->daddr;
1190                 fl4.saddr = iph->saddr;
1191                 fl4.flowi4_tos = RT_TOS(iph->tos);
1192                 fl4.flowi4_oif = rt->dst.dev->ifindex;
1193                 fl4.flowi4_iif = skb->dev->ifindex;
1194                 fl4.flowi4_mark = skb->mark;
1195 
1196                 rcu_read_lock();
1197                 if (fib_lookup(dev_net(rt->dst.dev), &fl4, &res, 0) == 0)
1198                         src = FIB_RES_PREFSRC(dev_net(rt->dst.dev), res);
1199                 else
1200                         src = inet_select_addr(rt->dst.dev,
1201                                                rt_nexthop(rt, iph->daddr),
1202                                                RT_SCOPE_UNIVERSE);
1203                 rcu_read_unlock();
1204         }
1205         memcpy(addr, &src, 4);
1206 }
1207 
1208 #ifdef CONFIG_IP_ROUTE_CLASSID
1209 static void set_class_tag(struct rtable *rt, u32 tag)
1210 {
1211         if (!(rt->dst.tclassid & 0xFFFF))
1212                 rt->dst.tclassid |= tag & 0xFFFF;
1213         if (!(rt->dst.tclassid & 0xFFFF0000))
1214                 rt->dst.tclassid |= tag & 0xFFFF0000;
1215 }
1216 #endif
1217 
1218 static unsigned int ipv4_default_advmss(const struct dst_entry *dst)
1219 {
1220         unsigned int advmss = dst_metric_raw(dst, RTAX_ADVMSS);
1221 
1222         if (advmss == 0) {
1223                 advmss = max_t(unsigned int, dst->dev->mtu - 40,
1224                                ip_rt_min_advmss);
1225                 if (advmss > 65535 - 40)
1226                         advmss = 65535 - 40;
1227         }
1228         return advmss;
1229 }
1230 
1231 static unsigned int ipv4_mtu(const struct dst_entry *dst)
1232 {
1233         const struct rtable *rt = (const struct rtable *) dst;
1234         unsigned int mtu = rt->rt_pmtu;
1235 
1236         if (!mtu || time_after_eq(jiffies, rt->dst.expires))
1237                 mtu = dst_metric_raw(dst, RTAX_MTU);
1238 
1239         if (mtu)
1240                 return mtu;
1241 
1242         mtu = dst->dev->mtu;
1243 
1244         if (unlikely(dst_metric_locked(dst, RTAX_MTU))) {
1245                 if (rt->rt_uses_gateway && mtu > 576)
1246                         mtu = 576;
1247         }
1248 
1249         return min_t(unsigned int, mtu, IP_MAX_MTU);
1250 }
1251 
1252 static struct fib_nh_exception *find_exception(struct fib_nh *nh, __be32 daddr)
1253 {
1254         struct fnhe_hash_bucket *hash = rcu_dereference(nh->nh_exceptions);
1255         struct fib_nh_exception *fnhe;
1256         u32 hval;
1257 
1258         if (!hash)
1259                 return NULL;
1260 
1261         hval = fnhe_hashfun(daddr);
1262 
1263         for (fnhe = rcu_dereference(hash[hval].chain); fnhe;
1264              fnhe = rcu_dereference(fnhe->fnhe_next)) {
1265                 if (fnhe->fnhe_daddr == daddr)
1266                         return fnhe;
1267         }
1268         return NULL;
1269 }
1270 
1271 static bool rt_bind_exception(struct rtable *rt, struct fib_nh_exception *fnhe,
1272                               __be32 daddr)
1273 {
1274         bool ret = false;
1275 
1276         spin_lock_bh(&fnhe_lock);
1277 
1278         if (daddr == fnhe->fnhe_daddr) {
1279                 struct rtable __rcu **porig;
1280                 struct rtable *orig;
1281                 int genid = fnhe_genid(dev_net(rt->dst.dev));
1282 
1283                 if (rt_is_input_route(rt))
1284                         porig = &fnhe->fnhe_rth_input;
1285                 else
1286                         porig = &fnhe->fnhe_rth_output;
1287                 orig = rcu_dereference(*porig);
1288 
1289                 if (fnhe->fnhe_genid != genid) {
1290                         fnhe->fnhe_genid = genid;
1291                         fnhe->fnhe_gw = 0;
1292                         fnhe->fnhe_pmtu = 0;
1293                         fnhe->fnhe_expires = 0;
1294                         fnhe_flush_routes(fnhe);
1295                         orig = NULL;
1296                 }
1297                 fill_route_from_fnhe(rt, fnhe);
1298                 if (!rt->rt_gateway)
1299                         rt->rt_gateway = daddr;
1300 
1301                 if (!(rt->dst.flags & DST_NOCACHE)) {
1302                         rcu_assign_pointer(*porig, rt);
1303                         if (orig)
1304                                 rt_free(orig);
1305                         ret = true;
1306                 }
1307 
1308                 fnhe->fnhe_stamp = jiffies;
1309         }
1310         spin_unlock_bh(&fnhe_lock);
1311 
1312         return ret;
1313 }
1314 
1315 static bool rt_cache_route(struct fib_nh *nh, struct rtable *rt)
1316 {
1317         struct rtable *orig, *prev, **p;
1318         bool ret = true;
1319 
1320         if (rt_is_input_route(rt)) {
1321                 p = (struct rtable **)&nh->nh_rth_input;
1322         } else {
1323                 p = (struct rtable **)raw_cpu_ptr(nh->nh_pcpu_rth_output);
1324         }
1325         orig = *p;
1326 
1327         prev = cmpxchg(p, orig, rt);
1328         if (prev == orig) {
1329                 if (orig)
1330                         rt_free(orig);
1331         } else
1332                 ret = false;
1333 
1334         return ret;
1335 }
1336 
1337 struct uncached_list {
1338         spinlock_t              lock;
1339         struct list_head        head;
1340 };
1341 
1342 static DEFINE_PER_CPU_ALIGNED(struct uncached_list, rt_uncached_list);
1343 
1344 static void rt_add_uncached_list(struct rtable *rt)
1345 {
1346         struct uncached_list *ul = raw_cpu_ptr(&rt_uncached_list);
1347 
1348         rt->rt_uncached_list = ul;
1349 
1350         spin_lock_bh(&ul->lock);
1351         list_add_tail(&rt->rt_uncached, &ul->head);
1352         spin_unlock_bh(&ul->lock);
1353 }
1354 
1355 static void ipv4_dst_destroy(struct dst_entry *dst)
1356 {
1357         struct rtable *rt = (struct rtable *) dst;
1358 
1359         if (!list_empty(&rt->rt_uncached)) {
1360                 struct uncached_list *ul = rt->rt_uncached_list;
1361 
1362                 spin_lock_bh(&ul->lock);
1363                 list_del(&rt->rt_uncached);
1364                 spin_unlock_bh(&ul->lock);
1365         }
1366 }
1367 
1368 void rt_flush_dev(struct net_device *dev)
1369 {
1370         struct net *net = dev_net(dev);
1371         struct rtable *rt;
1372         int cpu;
1373 
1374         for_each_possible_cpu(cpu) {
1375                 struct uncached_list *ul = &per_cpu(rt_uncached_list, cpu);
1376 
1377                 spin_lock_bh(&ul->lock);
1378                 list_for_each_entry(rt, &ul->head, rt_uncached) {
1379                         if (rt->dst.dev != dev)
1380                                 continue;
1381                         rt->dst.dev = net->loopback_dev;
1382                         dev_hold(rt->dst.dev);
1383                         dev_put(dev);
1384                 }
1385                 spin_unlock_bh(&ul->lock);
1386         }
1387 }
1388 
1389 static bool rt_cache_valid(const struct rtable *rt)
1390 {
1391         return  rt &&
1392                 rt->dst.obsolete == DST_OBSOLETE_FORCE_CHK &&
1393                 !rt_is_expired(rt);
1394 }
1395 
1396 static void rt_set_nexthop(struct rtable *rt, __be32 daddr,
1397                            const struct fib_result *res,
1398                            struct fib_nh_exception *fnhe,
1399                            struct fib_info *fi, u16 type, u32 itag)
1400 {
1401         bool cached = false;
1402 
1403         if (fi) {
1404                 struct fib_nh *nh = &FIB_RES_NH(*res);
1405 
1406                 if (nh->nh_gw && nh->nh_scope == RT_SCOPE_LINK) {
1407                         rt->rt_gateway = nh->nh_gw;
1408                         rt->rt_uses_gateway = 1;
1409                 }
1410                 dst_init_metrics(&rt->dst, fi->fib_metrics, true);
1411 #ifdef CONFIG_IP_ROUTE_CLASSID
1412                 rt->dst.tclassid = nh->nh_tclassid;
1413 #endif
1414                 rt->dst.lwtstate = lwtstate_get(nh->nh_lwtstate);
1415                 if (unlikely(fnhe))
1416                         cached = rt_bind_exception(rt, fnhe, daddr);
1417                 else if (!(rt->dst.flags & DST_NOCACHE))
1418                         cached = rt_cache_route(nh, rt);
1419                 if (unlikely(!cached)) {
1420                         /* Routes we intend to cache in nexthop exception or
1421                          * FIB nexthop have the DST_NOCACHE bit clear.
1422                          * However, if we are unsuccessful at storing this
1423                          * route into the cache we really need to set it.
1424                          */
1425                         rt->dst.flags |= DST_NOCACHE;
1426                         if (!rt->rt_gateway)
1427                                 rt->rt_gateway = daddr;
1428                         rt_add_uncached_list(rt);
1429                 }
1430         } else
1431                 rt_add_uncached_list(rt);
1432 
1433 #ifdef CONFIG_IP_ROUTE_CLASSID
1434 #ifdef CONFIG_IP_MULTIPLE_TABLES
1435         set_class_tag(rt, res->tclassid);
1436 #endif
1437         set_class_tag(rt, itag);
1438 #endif
1439 }
1440 
1441 static struct rtable *rt_dst_alloc(struct net_device *dev,
1442                                    unsigned int flags, u16 type,
1443                                    bool nopolicy, bool noxfrm, bool will_cache)
1444 {
1445         struct rtable *rt;
1446 
1447         rt = dst_alloc(&ipv4_dst_ops, dev, 1, DST_OBSOLETE_FORCE_CHK,
1448                        (will_cache ? 0 : (DST_HOST | DST_NOCACHE)) |
1449                        (nopolicy ? DST_NOPOLICY : 0) |
1450                        (noxfrm ? DST_NOXFRM : 0));
1451 
1452         if (rt) {
1453                 rt->rt_genid = rt_genid_ipv4(dev_net(dev));
1454                 rt->rt_flags = flags;
1455                 rt->rt_type = type;
1456                 rt->rt_is_input = 0;
1457                 rt->rt_iif = 0;
1458                 rt->rt_pmtu = 0;
1459                 rt->rt_gateway = 0;
1460                 rt->rt_uses_gateway = 0;
1461                 rt->rt_table_id = 0;
1462                 INIT_LIST_HEAD(&rt->rt_uncached);
1463 
1464                 rt->dst.output = ip_output;
1465                 if (flags & RTCF_LOCAL)
1466                         rt->dst.input = ip_local_deliver;
1467         }
1468 
1469         return rt;
1470 }
1471 
1472 /* called in rcu_read_lock() section */
1473 static int ip_route_input_mc(struct sk_buff *skb, __be32 daddr, __be32 saddr,
1474                                 u8 tos, struct net_device *dev, int our)
1475 {
1476         struct rtable *rth;
1477         struct in_device *in_dev = __in_dev_get_rcu(dev);
1478         unsigned int flags = RTCF_MULTICAST;
1479         u32 itag = 0;
1480         int err;
1481 
1482         /* Primary sanity checks. */
1483 
1484         if (!in_dev)
1485                 return -EINVAL;
1486 
1487         if (ipv4_is_multicast(saddr) || ipv4_is_lbcast(saddr) ||
1488             skb->protocol != htons(ETH_P_IP))
1489                 goto e_inval;
1490 
1491         if (ipv4_is_loopback(saddr) && !IN_DEV_ROUTE_LOCALNET(in_dev))
1492                 goto e_inval;
1493 
1494         if (ipv4_is_zeronet(saddr)) {
1495                 if (!ipv4_is_local_multicast(daddr))
1496                         goto e_inval;
1497         } else {
1498                 err = fib_validate_source(skb, saddr, 0, tos, 0, dev,
1499                                           in_dev, &itag);
1500                 if (err < 0)
1501                         goto e_err;
1502         }
1503         if (our)
1504                 flags |= RTCF_LOCAL;
1505 
1506         rth = rt_dst_alloc(dev_net(dev)->loopback_dev, flags, RTN_MULTICAST,
1507                            IN_DEV_CONF_GET(in_dev, NOPOLICY), false, false);
1508         if (!rth)
1509                 goto e_nobufs;
1510 
1511 #ifdef CONFIG_IP_ROUTE_CLASSID
1512         rth->dst.tclassid = itag;
1513 #endif
1514         rth->dst.output = ip_rt_bug;
1515         rth->rt_is_input= 1;
1516 
1517 #ifdef CONFIG_IP_MROUTE
1518         if (!ipv4_is_local_multicast(daddr) && IN_DEV_MFORWARD(in_dev))
1519                 rth->dst.input = ip_mr_input;
1520 #endif
1521         RT_CACHE_STAT_INC(in_slow_mc);
1522 
1523         skb_dst_set(skb, &rth->dst);
1524         return 0;
1525 
1526 e_nobufs:
1527         return -ENOBUFS;
1528 e_inval:
1529         return -EINVAL;
1530 e_err:
1531         return err;
1532 }
1533 
1534 
1535 static void ip_handle_martian_source(struct net_device *dev,
1536                                      struct in_device *in_dev,
1537                                      struct sk_buff *skb,
1538                                      __be32 daddr,
1539                                      __be32 saddr)
1540 {
1541         RT_CACHE_STAT_INC(in_martian_src);
1542 #ifdef CONFIG_IP_ROUTE_VERBOSE
1543         if (IN_DEV_LOG_MARTIANS(in_dev) && net_ratelimit()) {
1544                 /*
1545                  *      RFC1812 recommendation, if source is martian,
1546                  *      the only hint is MAC header.
1547                  */
1548                 pr_warn("martian source %pI4 from %pI4, on dev %s\n",
1549                         &daddr, &saddr, dev->name);
1550                 if (dev->hard_header_len && skb_mac_header_was_set(skb)) {
1551                         print_hex_dump(KERN_WARNING, "ll header: ",
1552                                        DUMP_PREFIX_OFFSET, 16, 1,
1553                                        skb_mac_header(skb),
1554                                        dev->hard_header_len, true);
1555                 }
1556         }
1557 #endif
1558 }
1559 
1560 static void ip_del_fnhe(struct fib_nh *nh, __be32 daddr)
1561 {
1562         struct fnhe_hash_bucket *hash;
1563         struct fib_nh_exception *fnhe, __rcu **fnhe_p;
1564         u32 hval = fnhe_hashfun(daddr);
1565 
1566         spin_lock_bh(&fnhe_lock);
1567 
1568         hash = rcu_dereference_protected(nh->nh_exceptions,
1569                                          lockdep_is_held(&fnhe_lock));
1570         hash += hval;
1571 
1572         fnhe_p = &hash->chain;
1573         fnhe = rcu_dereference_protected(*fnhe_p, lockdep_is_held(&fnhe_lock));
1574         while (fnhe) {
1575                 if (fnhe->fnhe_daddr == daddr) {
1576                         rcu_assign_pointer(*fnhe_p, rcu_dereference_protected(
1577                                 fnhe->fnhe_next, lockdep_is_held(&fnhe_lock)));
1578                         fnhe_flush_routes(fnhe);
1579                         kfree_rcu(fnhe, rcu);
1580                         break;
1581                 }
1582                 fnhe_p = &fnhe->fnhe_next;
1583                 fnhe = rcu_dereference_protected(fnhe->fnhe_next,
1584                                                  lockdep_is_held(&fnhe_lock));
1585         }
1586 
1587         spin_unlock_bh(&fnhe_lock);
1588 }
1589 
1590 /* called in rcu_read_lock() section */
1591 static int __mkroute_input(struct sk_buff *skb,
1592                            const struct fib_result *res,
1593                            struct in_device *in_dev,
1594                            __be32 daddr, __be32 saddr, u32 tos)
1595 {
1596         struct fib_nh_exception *fnhe;
1597         struct rtable *rth;
1598         int err;
1599         struct in_device *out_dev;
1600         bool do_cache;
1601         u32 itag = 0;
1602 
1603         /* get a working reference to the output device */
1604         out_dev = __in_dev_get_rcu(FIB_RES_DEV(*res));
1605         if (!out_dev) {
1606                 net_crit_ratelimited("Bug in ip_route_input_slow(). Please report.\n");
1607                 return -EINVAL;
1608         }
1609 
1610         err = fib_validate_source(skb, saddr, daddr, tos, FIB_RES_OIF(*res),
1611                                   in_dev->dev, in_dev, &itag);
1612         if (err < 0) {
1613                 ip_handle_martian_source(in_dev->dev, in_dev, skb, daddr,
1614                                          saddr);
1615 
1616                 goto cleanup;
1617         }
1618 
1619         do_cache = res->fi && !itag;
1620         if (out_dev == in_dev && err && IN_DEV_TX_REDIRECTS(out_dev) &&
1621             skb->protocol == htons(ETH_P_IP) &&
1622             (IN_DEV_SHARED_MEDIA(out_dev) ||
1623              inet_addr_onlink(out_dev, saddr, FIB_RES_GW(*res))))
1624                 IPCB(skb)->flags |= IPSKB_DOREDIRECT;
1625 
1626         if (skb->protocol != htons(ETH_P_IP)) {
1627                 /* Not IP (i.e. ARP). Do not create route, if it is
1628                  * invalid for proxy arp. DNAT routes are always valid.
1629                  *
1630                  * Proxy arp feature have been extended to allow, ARP
1631                  * replies back to the same interface, to support
1632                  * Private VLAN switch technologies. See arp.c.
1633                  */
1634                 if (out_dev == in_dev &&
1635                     IN_DEV_PROXY_ARP_PVLAN(in_dev) == 0) {
1636                         err = -EINVAL;
1637                         goto cleanup;
1638                 }
1639         }
1640 
1641         fnhe = find_exception(&FIB_RES_NH(*res), daddr);
1642         if (do_cache) {
1643                 if (fnhe) {
1644                         rth = rcu_dereference(fnhe->fnhe_rth_input);
1645                         if (rth && rth->dst.expires &&
1646                             time_after(jiffies, rth->dst.expires)) {
1647                                 ip_del_fnhe(&FIB_RES_NH(*res), daddr);
1648                                 fnhe = NULL;
1649                         } else {
1650                                 goto rt_cache;
1651                         }
1652                 }
1653 
1654                 rth = rcu_dereference(FIB_RES_NH(*res).nh_rth_input);
1655 
1656 rt_cache:
1657                 if (rt_cache_valid(rth)) {
1658                         skb_dst_set_noref(skb, &rth->dst);
1659                         goto out;
1660                 }
1661         }
1662 
1663         rth = rt_dst_alloc(out_dev->dev, 0, res->type,
1664                            IN_DEV_CONF_GET(in_dev, NOPOLICY),
1665                            IN_DEV_CONF_GET(out_dev, NOXFRM), do_cache);
1666         if (!rth) {
1667                 err = -ENOBUFS;
1668                 goto cleanup;
1669         }
1670 
1671         rth->rt_is_input = 1;
1672         if (res->table)
1673                 rth->rt_table_id = res->table->tb_id;
1674         RT_CACHE_STAT_INC(in_slow_tot);
1675 
1676         rth->dst.input = ip_forward;
1677 
1678         rt_set_nexthop(rth, daddr, res, fnhe, res->fi, res->type, itag);
1679         if (lwtunnel_output_redirect(rth->dst.lwtstate)) {
1680                 rth->dst.lwtstate->orig_output = rth->dst.output;
1681                 rth->dst.output = lwtunnel_output;
1682         }
1683         if (lwtunnel_input_redirect(rth->dst.lwtstate)) {
1684                 rth->dst.lwtstate->orig_input = rth->dst.input;
1685                 rth->dst.input = lwtunnel_input;
1686         }
1687         skb_dst_set(skb, &rth->dst);
1688 out:
1689         err = 0;
1690  cleanup:
1691         return err;
1692 }
1693 
1694 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1695 
1696 /* To make ICMP packets follow the right flow, the multipath hash is
1697  * calculated from the inner IP addresses in reverse order.
1698  */
1699 static int ip_multipath_icmp_hash(struct sk_buff *skb)
1700 {
1701         const struct iphdr *outer_iph = ip_hdr(skb);
1702         struct icmphdr _icmph;
1703         const struct icmphdr *icmph;
1704         struct iphdr _inner_iph;
1705         const struct iphdr *inner_iph;
1706 
1707         if (unlikely((outer_iph->frag_off & htons(IP_OFFSET)) != 0))
1708                 goto standard_hash;
1709 
1710         icmph = skb_header_pointer(skb, outer_iph->ihl * 4, sizeof(_icmph),
1711                                    &_icmph);
1712         if (!icmph)
1713                 goto standard_hash;
1714 
1715         if (icmph->type != ICMP_DEST_UNREACH &&
1716             icmph->type != ICMP_REDIRECT &&
1717             icmph->type != ICMP_TIME_EXCEEDED &&
1718             icmph->type != ICMP_PARAMETERPROB) {
1719                 goto standard_hash;
1720         }
1721 
1722         inner_iph = skb_header_pointer(skb,
1723                                        outer_iph->ihl * 4 + sizeof(_icmph),
1724                                        sizeof(_inner_iph), &_inner_iph);
1725         if (!inner_iph)
1726                 goto standard_hash;
1727 
1728         return fib_multipath_hash(inner_iph->daddr, inner_iph->saddr);
1729 
1730 standard_hash:
1731         return fib_multipath_hash(outer_iph->saddr, outer_iph->daddr);
1732 }
1733 
1734 #endif /* CONFIG_IP_ROUTE_MULTIPATH */
1735 
1736 static int ip_mkroute_input(struct sk_buff *skb,
1737                             struct fib_result *res,
1738                             const struct flowi4 *fl4,
1739                             struct in_device *in_dev,
1740                             __be32 daddr, __be32 saddr, u32 tos)
1741 {
1742 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1743         if (res->fi && res->fi->fib_nhs > 1) {
1744                 int h;
1745 
1746                 if (unlikely(ip_hdr(skb)->protocol == IPPROTO_ICMP))
1747                         h = ip_multipath_icmp_hash(skb);
1748                 else
1749                         h = fib_multipath_hash(saddr, daddr);
1750                 fib_select_multipath(res, h);
1751         }
1752 #endif
1753 
1754         /* create a routing cache entry */
1755         return __mkroute_input(skb, res, in_dev, daddr, saddr, tos);
1756 }
1757 
1758 /*
1759  *      NOTE. We drop all the packets that has local source
1760  *      addresses, because every properly looped back packet
1761  *      must have correct destination already attached by output routine.
1762  *
1763  *      Such approach solves two big problems:
1764  *      1. Not simplex devices are handled properly.
1765  *      2. IP spoofing attempts are filtered with 100% of guarantee.
1766  *      called with rcu_read_lock()
1767  */
1768 
1769 static int ip_route_input_slow(struct sk_buff *skb, __be32 daddr, __be32 saddr,
1770                                u8 tos, struct net_device *dev)
1771 {
1772         struct fib_result res;
1773         struct in_device *in_dev = __in_dev_get_rcu(dev);
1774         struct ip_tunnel_info *tun_info;
1775         struct flowi4   fl4;
1776         unsigned int    flags = 0;
1777         u32             itag = 0;
1778         struct rtable   *rth;
1779         int             err = -EINVAL;
1780         struct net    *net = dev_net(dev);
1781         bool do_cache;
1782 
1783         /* IP on this device is disabled. */
1784 
1785         if (!in_dev)
1786                 goto out;
1787 
1788         /* Check for the most weird martians, which can be not detected
1789            by fib_lookup.
1790          */
1791 
1792         tun_info = skb_tunnel_info(skb);
1793         if (tun_info && !(tun_info->mode & IP_TUNNEL_INFO_TX))
1794                 fl4.flowi4_tun_key.tun_id = tun_info->key.tun_id;
1795         else
1796                 fl4.flowi4_tun_key.tun_id = 0;
1797         skb_dst_drop(skb);
1798 
1799         if (ipv4_is_multicast(saddr) || ipv4_is_lbcast(saddr))
1800                 goto martian_source;
1801 
1802         res.fi = NULL;
1803         res.table = NULL;
1804         if (ipv4_is_lbcast(daddr) || (saddr == 0 && daddr == 0))
1805                 goto brd_input;
1806 
1807         /* Accept zero addresses only to limited broadcast;
1808          * I even do not know to fix it or not. Waiting for complains :-)
1809          */
1810         if (ipv4_is_zeronet(saddr))
1811                 goto martian_source;
1812 
1813         if (ipv4_is_zeronet(daddr))
1814                 goto martian_destination;
1815 
1816         /* Following code try to avoid calling IN_DEV_NET_ROUTE_LOCALNET(),
1817          * and call it once if daddr or/and saddr are loopback addresses
1818          */
1819         if (ipv4_is_loopback(daddr)) {
1820                 if (!IN_DEV_NET_ROUTE_LOCALNET(in_dev, net))
1821                         goto martian_destination;
1822         } else if (ipv4_is_loopback(saddr)) {
1823                 if (!IN_DEV_NET_ROUTE_LOCALNET(in_dev, net))
1824                         goto martian_source;
1825         }
1826 
1827         /*
1828          *      Now we are ready to route packet.
1829          */
1830         fl4.flowi4_oif = 0;
1831         fl4.flowi4_iif = l3mdev_fib_oif_rcu(dev);
1832         fl4.flowi4_mark = skb->mark;
1833         fl4.flowi4_tos = tos;
1834         fl4.flowi4_scope = RT_SCOPE_UNIVERSE;
1835         fl4.flowi4_flags = 0;
1836         fl4.daddr = daddr;
1837         fl4.saddr = saddr;
1838         err = fib_lookup(net, &fl4, &res, 0);
1839         if (err != 0) {
1840                 if (!IN_DEV_FORWARD(in_dev))
1841                         err = -EHOSTUNREACH;
1842                 goto no_route;
1843         }
1844 
1845         if (res.type == RTN_BROADCAST)
1846                 goto brd_input;
1847 
1848         if (res.type == RTN_LOCAL) {
1849                 err = fib_validate_source(skb, saddr, daddr, tos,
1850                                           0, dev, in_dev, &itag);
1851                 if (err < 0)
1852                         goto martian_source;
1853                 goto local_input;
1854         }
1855 
1856         if (!IN_DEV_FORWARD(in_dev)) {
1857                 err = -EHOSTUNREACH;
1858                 goto no_route;
1859         }
1860         if (res.type != RTN_UNICAST)
1861                 goto martian_destination;
1862 
1863         err = ip_mkroute_input(skb, &res, &fl4, in_dev, daddr, saddr, tos);
1864 out:    return err;
1865 
1866 brd_input:
1867         if (skb->protocol != htons(ETH_P_IP))
1868                 goto e_inval;
1869 
1870         if (!ipv4_is_zeronet(saddr)) {
1871                 err = fib_validate_source(skb, saddr, 0, tos, 0, dev,
1872                                           in_dev, &itag);
1873                 if (err < 0)
1874                         goto martian_source;
1875         }
1876         flags |= RTCF_BROADCAST;
1877         res.type = RTN_BROADCAST;
1878         RT_CACHE_STAT_INC(in_brd);
1879 
1880 local_input:
1881         do_cache = false;
1882         if (res.fi) {
1883                 if (!itag) {
1884                         rth = rcu_dereference(FIB_RES_NH(res).nh_rth_input);
1885                         if (rt_cache_valid(rth)) {
1886                                 skb_dst_set_noref(skb, &rth->dst);
1887                                 err = 0;
1888                                 goto out;
1889                         }
1890                         do_cache = true;
1891                 }
1892         }
1893 
1894         rth = rt_dst_alloc(net->loopback_dev, flags | RTCF_LOCAL, res.type,
1895                            IN_DEV_CONF_GET(in_dev, NOPOLICY), false, do_cache);
1896         if (!rth)
1897                 goto e_nobufs;
1898 
1899         rth->dst.output= ip_rt_bug;
1900 #ifdef CONFIG_IP_ROUTE_CLASSID
1901         rth->dst.tclassid = itag;
1902 #endif
1903         rth->rt_is_input = 1;
1904         if (res.table)
1905                 rth->rt_table_id = res.table->tb_id;
1906 
1907         RT_CACHE_STAT_INC(in_slow_tot);
1908         if (res.type == RTN_UNREACHABLE) {
1909                 rth->dst.input= ip_error;
1910                 rth->dst.error= -err;
1911                 rth->rt_flags   &= ~RTCF_LOCAL;
1912         }
1913         if (do_cache) {
1914                 if (unlikely(!rt_cache_route(&FIB_RES_NH(res), rth))) {
1915                         rth->dst.flags |= DST_NOCACHE;
1916                         rt_add_uncached_list(rth);
1917                 }
1918         }
1919         skb_dst_set(skb, &rth->dst);
1920         err = 0;
1921         goto out;
1922 
1923 no_route:
1924         RT_CACHE_STAT_INC(in_no_route);
1925         res.type = RTN_UNREACHABLE;
1926         res.fi = NULL;
1927         res.table = NULL;
1928         goto local_input;
1929 
1930         /*
1931          *      Do not cache martian addresses: they should be logged (RFC1812)
1932          */
1933 martian_destination:
1934         RT_CACHE_STAT_INC(in_martian_dst);
1935 #ifdef CONFIG_IP_ROUTE_VERBOSE
1936         if (IN_DEV_LOG_MARTIANS(in_dev))
1937                 net_warn_ratelimited("martian destination %pI4 from %pI4, dev %s\n",
1938                                      &daddr, &saddr, dev->name);
1939 #endif
1940 
1941 e_inval:
1942         err = -EINVAL;
1943         goto out;
1944 
1945 e_nobufs:
1946         err = -ENOBUFS;
1947         goto out;
1948 
1949 martian_source:
1950         ip_handle_martian_source(dev, in_dev, skb, daddr, saddr);
1951         goto out;
1952 }
1953 
1954 int ip_route_input_noref(struct sk_buff *skb, __be32 daddr, __be32 saddr,
1955                          u8 tos, struct net_device *dev)
1956 {
1957         int res;
1958 
1959         rcu_read_lock();
1960 
1961         /* Multicast recognition logic is moved from route cache to here.
1962            The problem was that too many Ethernet cards have broken/missing
1963            hardware multicast filters :-( As result the host on multicasting
1964            network acquires a lot of useless route cache entries, sort of
1965            SDR messages from all the world. Now we try to get rid of them.
1966            Really, provided software IP multicast filter is organized
1967            reasonably (at least, hashed), it does not result in a slowdown
1968            comparing with route cache reject entries.
1969            Note, that multicast routers are not affected, because
1970            route cache entry is created eventually.
1971          */
1972         if (ipv4_is_multicast(daddr)) {
1973                 struct in_device *in_dev = __in_dev_get_rcu(dev);
1974 
1975                 if (in_dev) {
1976                         int our = ip_check_mc_rcu(in_dev, daddr, saddr,
1977                                                   ip_hdr(skb)->protocol);
1978                         if (our
1979 #ifdef CONFIG_IP_MROUTE
1980                                 ||
1981                             (!ipv4_is_local_multicast(daddr) &&
1982                              IN_DEV_MFORWARD(in_dev))
1983 #endif
1984                            ) {
1985                                 int res = ip_route_input_mc(skb, daddr, saddr,
1986                                                             tos, dev, our);
1987                                 rcu_read_unlock();
1988                                 return res;
1989                         }
1990                 }
1991                 rcu_read_unlock();
1992                 return -EINVAL;
1993         }
1994         res = ip_route_input_slow(skb, daddr, saddr, tos, dev);
1995         rcu_read_unlock();
1996         return res;
1997 }
1998 EXPORT_SYMBOL(ip_route_input_noref);
1999 
2000 /* called with rcu_read_lock() */
2001 static struct rtable *__mkroute_output(const struct fib_result *res,
2002                                        const struct flowi4 *fl4, int orig_oif,
2003                                        struct net_device *dev_out,
2004                                        unsigned int flags)
2005 {
2006         struct fib_info *fi = res->fi;
2007         struct fib_nh_exception *fnhe;
2008         struct in_device *in_dev;
2009         u16 type = res->type;
2010         struct rtable *rth;
2011         bool do_cache;
2012 
2013         in_dev = __in_dev_get_rcu(dev_out);
2014         if (!in_dev)
2015                 return ERR_PTR(-EINVAL);
2016 
2017         if (likely(!IN_DEV_ROUTE_LOCALNET(in_dev)))
2018                 if (ipv4_is_loopback(fl4->saddr) && !(dev_out->flags & IFF_LOOPBACK))
2019                         return ERR_PTR(-EINVAL);
2020 
2021         if (ipv4_is_lbcast(fl4->daddr))
2022                 type = RTN_BROADCAST;
2023         else if (ipv4_is_multicast(fl4->daddr))
2024                 type = RTN_MULTICAST;
2025         else if (ipv4_is_zeronet(fl4->daddr))
2026                 return ERR_PTR(-EINVAL);
2027 
2028         if (dev_out->flags & IFF_LOOPBACK)
2029                 flags |= RTCF_LOCAL;
2030 
2031         do_cache = true;
2032         if (type == RTN_BROADCAST) {
2033                 flags |= RTCF_BROADCAST | RTCF_LOCAL;
2034                 fi = NULL;
2035         } else if (type == RTN_MULTICAST) {
2036                 flags |= RTCF_MULTICAST | RTCF_LOCAL;
2037                 if (!ip_check_mc_rcu(in_dev, fl4->daddr, fl4->saddr,
2038                                      fl4->flowi4_proto))
2039                         flags &= ~RTCF_LOCAL;
2040                 else
2041                         do_cache = false;
2042                 /* If multicast route do not exist use
2043                  * default one, but do not gateway in this case.
2044                  * Yes, it is hack.
2045                  */
2046                 if (fi && res->prefixlen < 4)
2047                         fi = NULL;
2048         }
2049 
2050         fnhe = NULL;
2051         do_cache &= fi != NULL;
2052         if (do_cache) {
2053                 struct rtable __rcu **prth;
2054                 struct fib_nh *nh = &FIB_RES_NH(*res);
2055 
2056                 fnhe = find_exception(nh, fl4->daddr);
2057                 if (fnhe) {
2058                         prth = &fnhe->fnhe_rth_output;
2059                         rth = rcu_dereference(*prth);
2060                         if (rth && rth->dst.expires &&
2061                             time_after(jiffies, rth->dst.expires)) {
2062                                 ip_del_fnhe(nh, fl4->daddr);
2063                                 fnhe = NULL;
2064                         } else {
2065                                 goto rt_cache;
2066                         }
2067                 }
2068 
2069                 if (unlikely(fl4->flowi4_flags &
2070                              FLOWI_FLAG_KNOWN_NH &&
2071                              !(nh->nh_gw &&
2072                                nh->nh_scope == RT_SCOPE_LINK))) {
2073                         do_cache = false;
2074                         goto add;
2075                 }
2076                 prth = raw_cpu_ptr(nh->nh_pcpu_rth_output);
2077                 rth = rcu_dereference(*prth);
2078 
2079 rt_cache:
2080                 if (rt_cache_valid(rth)) {
2081                         dst_hold(&rth->dst);
2082                         return rth;
2083                 }
2084         }
2085 
2086 add:
2087         rth = rt_dst_alloc(dev_out, flags, type,
2088                            IN_DEV_CONF_GET(in_dev, NOPOLICY),
2089                            IN_DEV_CONF_GET(in_dev, NOXFRM),
2090                            do_cache);
2091         if (!rth)
2092                 return ERR_PTR(-ENOBUFS);
2093 
2094         rth->rt_iif     = orig_oif ? : 0;
2095         if (res->table)
2096                 rth->rt_table_id = res->table->tb_id;
2097 
2098         RT_CACHE_STAT_INC(out_slow_tot);
2099 
2100         if (flags & (RTCF_BROADCAST | RTCF_MULTICAST)) {
2101                 if (flags & RTCF_LOCAL &&
2102                     !(dev_out->flags & IFF_LOOPBACK)) {
2103                         rth->dst.output = ip_mc_output;
2104                         RT_CACHE_STAT_INC(out_slow_mc);
2105                 }
2106 #ifdef CONFIG_IP_MROUTE
2107                 if (type == RTN_MULTICAST) {
2108                         if (IN_DEV_MFORWARD(in_dev) &&
2109                             !ipv4_is_local_multicast(fl4->daddr)) {
2110                                 rth->dst.input = ip_mr_input;
2111                                 rth->dst.output = ip_mc_output;
2112                         }
2113                 }
2114 #endif
2115         }
2116 
2117         rt_set_nexthop(rth, fl4->daddr, res, fnhe, fi, type, 0);
2118         if (lwtunnel_output_redirect(rth->dst.lwtstate))
2119                 rth->dst.output = lwtunnel_output;
2120 
2121         return rth;
2122 }
2123 
2124 /*
2125  * Major route resolver routine.
2126  */
2127 
2128 struct rtable *__ip_route_output_key_hash(struct net *net, struct flowi4 *fl4,
2129                                           int mp_hash)
2130 {
2131         struct net_device *dev_out = NULL;
2132         __u8 tos = RT_FL_TOS(fl4);
2133         unsigned int flags = 0;
2134         struct fib_result res;
2135         struct rtable *rth;
2136         int orig_oif;
2137         int err = -ENETUNREACH;
2138 
2139         res.tclassid    = 0;
2140         res.fi          = NULL;
2141         res.table       = NULL;
2142 
2143         orig_oif = fl4->flowi4_oif;
2144 
2145         fl4->flowi4_iif = LOOPBACK_IFINDEX;
2146         fl4->flowi4_tos = tos & IPTOS_RT_MASK;
2147         fl4->flowi4_scope = ((tos & RTO_ONLINK) ?
2148                          RT_SCOPE_LINK : RT_SCOPE_UNIVERSE);
2149 
2150         rcu_read_lock();
2151         if (fl4->saddr) {
2152                 rth = ERR_PTR(-EINVAL);
2153                 if (ipv4_is_multicast(fl4->saddr) ||
2154                     ipv4_is_lbcast(fl4->saddr) ||
2155                     ipv4_is_zeronet(fl4->saddr))
2156                         goto out;
2157 
2158                 /* I removed check for oif == dev_out->oif here.
2159                    It was wrong for two reasons:
2160                    1. ip_dev_find(net, saddr) can return wrong iface, if saddr
2161                       is assigned to multiple interfaces.
2162                    2. Moreover, we are allowed to send packets with saddr
2163                       of another iface. --ANK
2164                  */
2165 
2166                 if (fl4->flowi4_oif == 0 &&
2167                     (ipv4_is_multicast(fl4->daddr) ||
2168                      ipv4_is_lbcast(fl4->daddr))) {
2169                         /* It is equivalent to inet_addr_type(saddr) == RTN_LOCAL */
2170                         dev_out = __ip_dev_find(net, fl4->saddr, false);
2171                         if (!dev_out)
2172                                 goto out;
2173 
2174                         /* Special hack: user can direct multicasts
2175                            and limited broadcast via necessary interface
2176                            without fiddling with IP_MULTICAST_IF or IP_PKTINFO.
2177                            This hack is not just for fun, it allows
2178                            vic,vat and friends to work.
2179                            They bind socket to loopback, set ttl to zero
2180                            and expect that it will work.
2181                            From the viewpoint of routing cache they are broken,
2182                            because we are not allowed to build multicast path
2183                            with loopback source addr (look, routing cache
2184                            cannot know, that ttl is zero, so that packet
2185                            will not leave this host and route is valid).
2186                            Luckily, this hack is good workaround.
2187                          */
2188 
2189                         fl4->flowi4_oif = dev_out->ifindex;
2190                         goto make_route;
2191                 }
2192 
2193                 if (!(fl4->flowi4_flags & FLOWI_FLAG_ANYSRC)) {
2194                         /* It is equivalent to inet_addr_type(saddr) == RTN_LOCAL */
2195                         if (!__ip_dev_find(net, fl4->saddr, false))
2196                                 goto out;
2197                 }
2198         }
2199 
2200 
2201         if (fl4->flowi4_oif) {
2202                 dev_out = dev_get_by_index_rcu(net, fl4->flowi4_oif);
2203                 rth = ERR_PTR(-ENODEV);
2204                 if (!dev_out)
2205                         goto out;
2206 
2207                 /* RACE: Check return value of inet_select_addr instead. */
2208                 if (!(dev_out->flags & IFF_UP) || !__in_dev_get_rcu(dev_out)) {
2209                         rth = ERR_PTR(-ENETUNREACH);
2210                         goto out;
2211                 }
2212                 if (ipv4_is_local_multicast(fl4->daddr) ||
2213                     ipv4_is_lbcast(fl4->daddr) ||
2214                     fl4->flowi4_proto == IPPROTO_IGMP) {
2215                         if (!fl4->saddr)
2216                                 fl4->saddr = inet_select_addr(dev_out, 0,
2217                                                               RT_SCOPE_LINK);
2218                         goto make_route;
2219                 }
2220                 if (!fl4->saddr) {
2221                         if (ipv4_is_multicast(fl4->daddr))
2222                                 fl4->saddr = inet_select_addr(dev_out, 0,
2223                                                               fl4->flowi4_scope);
2224                         else if (!fl4->daddr)
2225                                 fl4->saddr = inet_select_addr(dev_out, 0,
2226                                                               RT_SCOPE_HOST);
2227                 }
2228 
2229                 rth = l3mdev_get_rtable(dev_out, fl4);
2230                 if (rth)
2231                         goto out;
2232         }
2233 
2234         if (!fl4->daddr) {
2235                 fl4->daddr = fl4->saddr;
2236                 if (!fl4->daddr)
2237                         fl4->daddr = fl4->saddr = htonl(INADDR_LOOPBACK);
2238                 dev_out = net->loopback_dev;
2239                 fl4->flowi4_oif = LOOPBACK_IFINDEX;
2240                 res.type = RTN_LOCAL;
2241                 flags |= RTCF_LOCAL;
2242                 goto make_route;
2243         }
2244 
2245         err = fib_lookup(net, fl4, &res, 0);
2246         if (err) {
2247                 res.fi = NULL;
2248                 res.table = NULL;
2249                 if (fl4->flowi4_oif &&
2250                     !netif_index_is_l3_master(net, fl4->flowi4_oif)) {
2251                         /* Apparently, routing tables are wrong. Assume,
2252                            that the destination is on link.
2253 
2254                            WHY? DW.
2255                            Because we are allowed to send to iface
2256                            even if it has NO routes and NO assigned
2257                            addresses. When oif is specified, routing
2258                            tables are looked up with only one purpose:
2259                            to catch if destination is gatewayed, rather than
2260                            direct. Moreover, if MSG_DONTROUTE is set,
2261                            we send packet, ignoring both routing tables
2262                            and ifaddr state. --ANK
2263 
2264 
2265                            We could make it even if oif is unknown,
2266                            likely IPv6, but we do not.
2267                          */
2268 
2269                         if (fl4->saddr == 0)
2270                                 fl4->saddr = inet_select_addr(dev_out, 0,
2271                                                               RT_SCOPE_LINK);
2272                         res.type = RTN_UNICAST;
2273                         goto make_route;
2274                 }
2275                 rth = ERR_PTR(err);
2276                 goto out;
2277         }
2278 
2279         if (res.type == RTN_LOCAL) {
2280                 if (!fl4->saddr) {
2281                         if (res.fi->fib_prefsrc)
2282                                 fl4->saddr = res.fi->fib_prefsrc;
2283                         else
2284                                 fl4->saddr = fl4->daddr;
2285                 }
2286                 dev_out = net->loopback_dev;
2287                 fl4->flowi4_oif = dev_out->ifindex;
2288                 flags |= RTCF_LOCAL;
2289                 goto make_route;
2290         }
2291 
2292         fib_select_path(net, &res, fl4, mp_hash);
2293 
2294         dev_out = FIB_RES_DEV(res);
2295         fl4->flowi4_oif = dev_out->ifindex;
2296 
2297 
2298 make_route:
2299         rth = __mkroute_output(&res, fl4, orig_oif, dev_out, flags);
2300 
2301 out:
2302         rcu_read_unlock();
2303         return rth;
2304 }
2305 EXPORT_SYMBOL_GPL(__ip_route_output_key_hash);
2306 
2307 static struct dst_entry *ipv4_blackhole_dst_check(struct dst_entry *dst, u32 cookie)
2308 {
2309         return NULL;
2310 }
2311 
2312 static unsigned int ipv4_blackhole_mtu(const struct dst_entry *dst)
2313 {
2314         unsigned int mtu = dst_metric_raw(dst, RTAX_MTU);
2315 
2316         return mtu ? : dst->dev->mtu;
2317 }
2318 
2319 static void ipv4_rt_blackhole_update_pmtu(struct dst_entry *dst, struct sock *sk,
2320                                           struct sk_buff *skb, u32 mtu)
2321 {
2322 }
2323 
2324 static void ipv4_rt_blackhole_redirect(struct dst_entry *dst, struct sock *sk,
2325                                        struct sk_buff *skb)
2326 {
2327 }
2328 
2329 static u32 *ipv4_rt_blackhole_cow_metrics(struct dst_entry *dst,
2330                                           unsigned long old)
2331 {
2332         return NULL;
2333 }
2334 
2335 static struct dst_ops ipv4_dst_blackhole_ops = {
2336         .family                 =       AF_INET,
2337         .check                  =       ipv4_blackhole_dst_check,
2338         .mtu                    =       ipv4_blackhole_mtu,
2339         .default_advmss         =       ipv4_default_advmss,
2340         .update_pmtu            =       ipv4_rt_blackhole_update_pmtu,
2341         .redirect               =       ipv4_rt_blackhole_redirect,
2342         .cow_metrics            =       ipv4_rt_blackhole_cow_metrics,
2343         .neigh_lookup           =       ipv4_neigh_lookup,
2344 };
2345 
2346 struct dst_entry *ipv4_blackhole_route(struct net *net, struct dst_entry *dst_orig)
2347 {
2348         struct rtable *ort = (struct rtable *) dst_orig;
2349         struct rtable *rt;
2350 
2351         rt = dst_alloc(&ipv4_dst_blackhole_ops, NULL, 1, DST_OBSOLETE_NONE, 0);
2352         if (rt) {
2353                 struct dst_entry *new = &rt->dst;
2354 
2355                 new->__use = 1;
2356                 new->input = dst_discard;
2357                 new->output = dst_discard_out;
2358 
2359                 new->dev = ort->dst.dev;
2360                 if (new->dev)
2361                         dev_hold(new->dev);
2362 
2363                 rt->rt_is_input = ort->rt_is_input;
2364                 rt->rt_iif = ort->rt_iif;
2365                 rt->rt_pmtu = ort->rt_pmtu;
2366 
2367                 rt->rt_genid = rt_genid_ipv4(net);
2368                 rt->rt_flags = ort->rt_flags;
2369                 rt->rt_type = ort->rt_type;
2370                 rt->rt_gateway = ort->rt_gateway;
2371                 rt->rt_uses_gateway = ort->rt_uses_gateway;
2372 
2373                 INIT_LIST_HEAD(&rt->rt_uncached);
2374                 dst_free(new);
2375         }
2376 
2377         dst_release(dst_orig);
2378 
2379         return rt ? &rt->dst : ERR_PTR(-ENOMEM);
2380 }
2381 
2382 struct rtable *ip_route_output_flow(struct net *net, struct flowi4 *flp4,
2383                                     const struct sock *sk)
2384 {
2385         struct rtable *rt = __ip_route_output_key(net, flp4);
2386 
2387         if (IS_ERR(rt))
2388                 return rt;
2389 
2390         if (flp4->flowi4_proto)
2391                 rt = (struct rtable *)xfrm_lookup_route(net, &rt->dst,
2392                                                         flowi4_to_flowi(flp4),
2393                                                         sk, 0);
2394 
2395         return rt;
2396 }
2397 EXPORT_SYMBOL_GPL(ip_route_output_flow);
2398 
2399 static int rt_fill_info(struct net *net,  __be32 dst, __be32 src, u32 table_id,
2400                         struct flowi4 *fl4, struct sk_buff *skb, u32 portid,
2401                         u32 seq, int event, int nowait, unsigned int flags)
2402 {
2403         struct rtable *rt = skb_rtable(skb);
2404         struct rtmsg *r;
2405         struct nlmsghdr *nlh;
2406         unsigned long expires = 0;
2407         u32 error;
2408         u32 metrics[RTAX_MAX];
2409 
2410         nlh = nlmsg_put(skb, portid, seq, event, sizeof(*r), flags);
2411         if (!nlh)
2412                 return -EMSGSIZE;
2413 
2414         r = nlmsg_data(nlh);
2415         r->rtm_family    = AF_INET;
2416         r->rtm_dst_len  = 32;
2417         r->rtm_src_len  = 0;
2418         r->rtm_tos      = fl4->flowi4_tos;
2419         r->rtm_table    = table_id;
2420         if (nla_put_u32(skb, RTA_TABLE, table_id))
2421                 goto nla_put_failure;
2422         r->rtm_type     = rt->rt_type;
2423         r->rtm_scope    = RT_SCOPE_UNIVERSE;
2424         r->rtm_protocol = RTPROT_UNSPEC;
2425         r->rtm_flags    = (rt->rt_flags & ~0xFFFF) | RTM_F_CLONED;
2426         if (rt->rt_flags & RTCF_NOTIFY)
2427                 r->rtm_flags |= RTM_F_NOTIFY;
2428         if (IPCB(skb)->flags & IPSKB_DOREDIRECT)
2429                 r->rtm_flags |= RTCF_DOREDIRECT;
2430 
2431         if (nla_put_in_addr(skb, RTA_DST, dst))
2432                 goto nla_put_failure;
2433         if (src) {
2434                 r->rtm_src_len = 32;
2435                 if (nla_put_in_addr(skb, RTA_SRC, src))
2436                         goto nla_put_failure;
2437         }
2438         if (rt->dst.dev &&
2439             nla_put_u32(skb, RTA_OIF, rt->dst.dev->ifindex))
2440                 goto nla_put_failure;
2441 #ifdef CONFIG_IP_ROUTE_CLASSID
2442         if (rt->dst.tclassid &&
2443             nla_put_u32(skb, RTA_FLOW, rt->dst.tclassid))
2444                 goto nla_put_failure;
2445 #endif
2446         if (!rt_is_input_route(rt) &&
2447             fl4->saddr != src) {
2448                 if (nla_put_in_addr(skb, RTA_PREFSRC, fl4->saddr))
2449                         goto nla_put_failure;
2450         }
2451         if (rt->rt_uses_gateway &&
2452             nla_put_in_addr(skb, RTA_GATEWAY, rt->rt_gateway))
2453                 goto nla_put_failure;
2454 
2455         expires = rt->dst.expires;
2456         if (expires) {
2457                 unsigned long now = jiffies;
2458 
2459                 if (time_before(now, expires))
2460                         expires -= now;
2461                 else
2462                         expires = 0;
2463         }
2464 
2465         memcpy(metrics, dst_metrics_ptr(&rt->dst), sizeof(metrics));
2466         if (rt->rt_pmtu && expires)
2467                 metrics[RTAX_MTU - 1] = rt->rt_pmtu;
2468         if (rtnetlink_put_metrics(skb, metrics) < 0)
2469                 goto nla_put_failure;
2470 
2471         if (fl4->flowi4_mark &&
2472             nla_put_u32(skb, RTA_MARK, fl4->flowi4_mark))
2473                 goto nla_put_failure;
2474 
2475         error = rt->dst.error;
2476 
2477         if (rt_is_input_route(rt)) {
2478 #ifdef CONFIG_IP_MROUTE
2479                 if (ipv4_is_multicast(dst) && !ipv4_is_local_multicast(dst) &&
2480                     IPV4_DEVCONF_ALL(net, MC_FORWARDING)) {
2481                         int err = ipmr_get_route(net, skb,
2482                                                  fl4->saddr, fl4->daddr,
2483                                                  r, nowait);
2484                         if (err <= 0) {
2485                                 if (!nowait) {
2486                                         if (err == 0)
2487                                                 return 0;
2488                                         goto nla_put_failure;
2489                                 } else {
2490                                         if (err == -EMSGSIZE)
2491                                                 goto nla_put_failure;
2492                                         error = err;
2493                                 }
2494                         }
2495                 } else
2496 #endif
2497                         if (nla_put_u32(skb, RTA_IIF, skb->dev->ifindex))
2498                                 goto nla_put_failure;
2499         }
2500 
2501         if (rtnl_put_cacheinfo(skb, &rt->dst, 0, expires, error) < 0)
2502                 goto nla_put_failure;
2503 
2504         nlmsg_end(skb, nlh);
2505         return 0;
2506 
2507 nla_put_failure:
2508         nlmsg_cancel(skb, nlh);
2509         return -EMSGSIZE;
2510 }
2511 
2512 static int inet_rtm_getroute(struct sk_buff *in_skb, struct nlmsghdr *nlh)
2513 {
2514         struct net *net = sock_net(in_skb->sk);
2515         struct rtmsg *rtm;
2516         struct nlattr *tb[RTA_MAX+1];
2517         struct rtable *rt = NULL;
2518         struct flowi4 fl4;
2519         __be32 dst = 0;
2520         __be32 src = 0;
2521         u32 iif;
2522         int err;
2523         int mark;
2524         struct sk_buff *skb;
2525         u32 table_id = RT_TABLE_MAIN;
2526 
2527         err = nlmsg_parse(nlh, sizeof(*rtm), tb, RTA_MAX, rtm_ipv4_policy);
2528         if (err < 0)
2529                 goto errout;
2530 
2531         rtm = nlmsg_data(nlh);
2532 
2533         skb = alloc_skb(NLMSG_GOODSIZE, GFP_KERNEL);
2534         if (!skb) {
2535                 err = -ENOBUFS;
2536                 goto errout;
2537         }
2538 
2539         /* Reserve room for dummy headers, this skb can pass
2540            through good chunk of routing engine.
2541          */
2542         skb_reset_mac_header(skb);
2543         skb_reset_network_header(skb);
2544 
2545         /* Bugfix: need to give ip_route_input enough of an IP header to not gag. */
2546         ip_hdr(skb)->protocol = IPPROTO_ICMP;
2547         skb_reserve(skb, MAX_HEADER + sizeof(struct iphdr));
2548 
2549         src = tb[RTA_SRC] ? nla_get_in_addr(tb[RTA_SRC]) : 0;
2550         dst = tb[RTA_DST] ? nla_get_in_addr(tb[RTA_DST]) : 0;
2551         iif = tb[RTA_IIF] ? nla_get_u32(tb[RTA_IIF]) : 0;
2552         mark = tb[RTA_MARK] ? nla_get_u32(tb[RTA_MARK]) : 0;
2553 
2554         memset(&fl4, 0, sizeof(fl4));
2555         fl4.daddr = dst;
2556         fl4.saddr = src;
2557         fl4.flowi4_tos = rtm->rtm_tos;
2558         fl4.flowi4_oif = tb[RTA_OIF] ? nla_get_u32(tb[RTA_OIF]) : 0;
2559         fl4.flowi4_mark = mark;
2560 
2561         if (netif_index_is_l3_master(net, fl4.flowi4_oif))
2562                 fl4.flowi4_flags = FLOWI_FLAG_L3MDEV_SRC | FLOWI_FLAG_SKIP_NH_OIF;
2563 
2564         if (iif) {
2565                 struct net_device *dev;
2566 
2567                 dev = __dev_get_by_index(net, iif);
2568                 if (!dev) {
2569                         err = -ENODEV;
2570                         goto errout_free;
2571                 }
2572 
2573                 skb->protocol   = htons(ETH_P_IP);
2574                 skb->dev        = dev;
2575                 skb->mark       = mark;
2576                 local_bh_disable();
2577                 err = ip_route_input(skb, dst, src, rtm->rtm_tos, dev);
2578                 local_bh_enable();
2579 
2580                 rt = skb_rtable(skb);
2581                 if (err == 0 && rt->dst.error)
2582                         err = -rt->dst.error;
2583         } else {
2584                 rt = ip_route_output_key(net, &fl4);
2585 
2586                 err = 0;
2587                 if (IS_ERR(rt))
2588                         err = PTR_ERR(rt);
2589         }
2590 
2591         if (err)
2592                 goto errout_free;
2593 
2594         skb_dst_set(skb, &rt->dst);
2595         if (rtm->rtm_flags & RTM_F_NOTIFY)
2596                 rt->rt_flags |= RTCF_NOTIFY;
2597 
2598         if (rtm->rtm_flags & RTM_F_LOOKUP_TABLE)
2599                 table_id = rt->rt_table_id;
2600 
2601         err = rt_fill_info(net, dst, src, table_id, &fl4, skb,
2602                            NETLINK_CB(in_skb).portid, nlh->nlmsg_seq,
2603                            RTM_NEWROUTE, 0, 0);
2604         if (err < 0)
2605                 goto errout_free;
2606 
2607         err = rtnl_unicast(skb, net, NETLINK_CB(in_skb).portid);
2608 errout:
2609         return err;
2610 
2611 errout_free:
2612         kfree_skb(skb);
2613         goto errout;
2614 }
2615 
2616 void ip_rt_multicast_event(struct in_device *in_dev)
2617 {
2618         rt_cache_flush(dev_net(in_dev->dev));
2619 }
2620 
2621 #ifdef CONFIG_SYSCTL
2622 static int ip_rt_gc_interval __read_mostly  = 60 * HZ;
2623 static int ip_rt_gc_min_interval __read_mostly  = HZ / 2;
2624 static int ip_rt_gc_elasticity __read_mostly    = 8;
2625 
2626 static int ipv4_sysctl_rtcache_flush(struct ctl_table *__ctl, int write,
2627                                         void __user *buffer,
2628                                         size_t *lenp, loff_t *ppos)
2629 {
2630         struct net *net = (struct net *)__ctl->extra1;
2631 
2632         if (write) {
2633                 rt_cache_flush(net);
2634                 fnhe_genid_bump(net);
2635                 return 0;
2636         }
2637 
2638         return -EINVAL;
2639 }
2640 
2641 static struct ctl_table ipv4_route_table[] = {
2642         {
2643                 .procname       = "gc_thresh",
2644                 .data           = &ipv4_dst_ops.gc_thresh,
2645                 .maxlen         = sizeof(int),
2646                 .mode           = 0644,
2647                 .proc_handler   = proc_dointvec,
2648         },
2649         {
2650                 .procname       = "max_size",
2651                 .data           = &ip_rt_max_size,
2652                 .maxlen         = sizeof(int),
2653                 .mode           = 0644,
2654                 .proc_handler   = proc_dointvec,
2655         },
2656         {
2657                 /*  Deprecated. Use gc_min_interval_ms */
2658 
2659                 .procname       = "gc_min_interval",
2660                 .data           = &ip_rt_gc_min_interval,
2661                 .maxlen         = sizeof(int),
2662                 .mode           = 0644,
2663                 .proc_handler   = proc_dointvec_jiffies,
2664         },
2665         {
2666                 .procname       = "gc_min_interval_ms",
2667                 .data           = &ip_rt_gc_min_interval,
2668                 .maxlen         = sizeof(int),
2669                 .mode           = 0644,
2670                 .proc_handler   = proc_dointvec_ms_jiffies,
2671         },
2672         {
2673                 .procname       = "gc_timeout",
2674                 .data           = &ip_rt_gc_timeout,
2675                 .maxlen         = sizeof(int),
2676                 .mode           = 0644,
2677                 .proc_handler   = proc_dointvec_jiffies,
2678         },
2679         {
2680                 .procname       = "gc_interval",
2681                 .data           = &ip_rt_gc_interval,
2682                 .maxlen         = sizeof(int),
2683                 .mode           = 0644,
2684                 .proc_handler   = proc_dointvec_jiffies,
2685         },
2686         {
2687                 .procname       = "redirect_load",
2688                 .data           = &ip_rt_redirect_load,
2689                 .maxlen         = sizeof(int),
2690                 .mode           = 0644,
2691                 .proc_handler   = proc_dointvec,
2692         },
2693         {
2694                 .procname       = "redirect_number",
2695                 .data           = &ip_rt_redirect_number,
2696                 .maxlen         = sizeof(int),
2697                 .mode           = 0644,
2698                 .proc_handler   = proc_dointvec,
2699         },
2700         {
2701                 .procname       = "redirect_silence",
2702                 .data           = &ip_rt_redirect_silence,
2703                 .maxlen         = sizeof(int),
2704                 .mode           = 0644,
2705                 .proc_handler   = proc_dointvec,
2706         },
2707         {
2708                 .procname       = "error_cost",
2709                 .data           = &ip_rt_error_cost,
2710                 .maxlen         = sizeof(int),
2711                 .mode           = 0644,
2712                 .proc_handler   = proc_dointvec,
2713         },
2714         {
2715                 .procname       = "error_burst",
2716                 .data           = &ip_rt_error_burst,
2717                 .maxlen         = sizeof(int),
2718                 .mode           = 0644,
2719                 .proc_handler   = proc_dointvec,
2720         },
2721         {
2722                 .procname       = "gc_elasticity",
2723                 .data           = &ip_rt_gc_elasticity,
2724                 .maxlen         = sizeof(int),
2725                 .mode           = 0644,
2726                 .proc_handler   = proc_dointvec,
2727         },
2728         {
2729                 .procname       = "mtu_expires",
2730                 .data           = &ip_rt_mtu_expires,
2731                 .maxlen         = sizeof(int),
2732                 .mode           = 0644,
2733                 .proc_handler   = proc_dointvec_jiffies,
2734         },
2735         {
2736                 .procname       = "min_pmtu",
2737                 .data           = &ip_rt_min_pmtu,
2738                 .maxlen         = sizeof(int),
2739                 .mode           = 0644,
2740                 .proc_handler   = proc_dointvec,
2741         },
2742         {
2743                 .procname       = "min_adv_mss",
2744                 .data           = &ip_rt_min_advmss,
2745                 .maxlen         = sizeof(int),
2746                 .mode           = 0644,
2747                 .proc_handler   = proc_dointvec,
2748         },
2749         { }
2750 };
2751 
2752 static struct ctl_table ipv4_route_flush_table[] = {
2753         {
2754                 .procname       = "flush",
2755                 .maxlen         = sizeof(int),
2756                 .mode           = 0200,
2757                 .proc_handler   = ipv4_sysctl_rtcache_flush,
2758         },
2759         { },
2760 };
2761 
2762 static __net_init int sysctl_route_net_init(struct net *net)
2763 {
2764         struct ctl_table *tbl;
2765 
2766         tbl = ipv4_route_flush_table;
2767         if (!net_eq(net, &init_net)) {
2768                 tbl = kmemdup(tbl, sizeof(ipv4_route_flush_table), GFP_KERNEL);
2769                 if (!tbl)
2770                         goto err_dup;
2771 
2772                 /* Don't export sysctls to unprivileged users */
2773                 if (net->user_ns != &init_user_ns)
2774                         tbl[0].procname = NULL;
2775         }
2776         tbl[0].extra1 = net;
2777 
2778         net->ipv4.route_hdr = register_net_sysctl(net, "net/ipv4/route", tbl);
2779         if (!net->ipv4.route_hdr)
2780                 goto err_reg;
2781         return 0;
2782 
2783 err_reg:
2784         if (tbl != ipv4_route_flush_table)
2785                 kfree(tbl);
2786 err_dup:
2787         return -ENOMEM;
2788 }
2789 
2790 static __net_exit void sysctl_route_net_exit(struct net *net)
2791 {
2792         struct ctl_table *tbl;
2793 
2794         tbl = net->ipv4.route_hdr->ctl_table_arg;
2795         unregister_net_sysctl_table(net->ipv4.route_hdr);
2796         BUG_ON(tbl == ipv4_route_flush_table);
2797         kfree(tbl);
2798 }
2799 
2800 static __net_initdata struct pernet_operations sysctl_route_ops = {
2801         .init = sysctl_route_net_init,
2802         .exit = sysctl_route_net_exit,
2803 };
2804 #endif
2805 
2806 static __net_init int rt_genid_init(struct net *net)
2807 {
2808         atomic_set(&net->ipv4.rt_genid, 0);
2809         atomic_set(&net->fnhe_genid, 0);
2810         get_random_bytes(&net->ipv4.dev_addr_genid,
2811                          sizeof(net->ipv4.dev_addr_genid));
2812         return 0;
2813 }
2814 
2815 static __net_initdata struct pernet_operations rt_genid_ops = {
2816         .init = rt_genid_init,
2817 };
2818 
2819 static int __net_init ipv4_inetpeer_init(struct net *net)
2820 {
2821         struct inet_peer_base *bp = kmalloc(sizeof(*bp), GFP_KERNEL);
2822 
2823         if (!bp)
2824                 return -ENOMEM;
2825         inet_peer_base_init(bp);
2826         net->ipv4.peers = bp;
2827         return 0;
2828 }
2829 
2830 static void __net_exit ipv4_inetpeer_exit(struct net *net)
2831 {
2832         struct inet_peer_base *bp = net->ipv4.peers;
2833 
2834         net->ipv4.peers = NULL;
2835         inetpeer_invalidate_tree(bp);
2836         kfree(bp);
2837 }
2838 
2839 static __net_initdata struct pernet_operations ipv4_inetpeer_ops = {
2840         .init   =       ipv4_inetpeer_init,
2841         .exit   =       ipv4_inetpeer_exit,
2842 };
2843 
2844 #ifdef CONFIG_IP_ROUTE_CLASSID
2845 struct ip_rt_acct __percpu *ip_rt_acct __read_mostly;
2846 #endif /* CONFIG_IP_ROUTE_CLASSID */
2847 
2848 int __init ip_rt_init(void)
2849 {
2850         int rc = 0;
2851         int cpu;
2852 
2853         ip_idents = kmalloc(IP_IDENTS_SZ * sizeof(*ip_idents), GFP_KERNEL);
2854         if (!ip_idents)
2855                 panic("IP: failed to allocate ip_idents\n");
2856 
2857         prandom_bytes(ip_idents, IP_IDENTS_SZ * sizeof(*ip_idents));
2858 
2859         ip_tstamps = kcalloc(IP_IDENTS_SZ, sizeof(*ip_tstamps), GFP_KERNEL);
2860         if (!ip_tstamps)
2861                 panic("IP: failed to allocate ip_tstamps\n");
2862 
2863         for_each_possible_cpu(cpu) {
2864                 struct uncached_list *ul = &per_cpu(rt_uncached_list, cpu);
2865 
2866                 INIT_LIST_HEAD(&ul->head);
2867                 spin_lock_init(&ul->lock);
2868         }
2869 #ifdef CONFIG_IP_ROUTE_CLASSID
2870         ip_rt_acct = __alloc_percpu(256 * sizeof(struct ip_rt_acct), __alignof__(struct ip_rt_acct));
2871         if (!ip_rt_acct)
2872                 panic("IP: failed to allocate ip_rt_acct\n");
2873 #endif
2874 
2875         ipv4_dst_ops.kmem_cachep =
2876                 kmem_cache_create("ip_dst_cache", sizeof(struct rtable), 0,
2877                                   SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
2878 
2879         ipv4_dst_blackhole_ops.kmem_cachep = ipv4_dst_ops.kmem_cachep;
2880 
2881         if (dst_entries_init(&ipv4_dst_ops) < 0)
2882                 panic("IP: failed to allocate ipv4_dst_ops counter\n");
2883 
2884         if (dst_entries_init(&ipv4_dst_blackhole_ops) < 0)
2885                 panic("IP: failed to allocate ipv4_dst_blackhole_ops counter\n");
2886 
2887         ipv4_dst_ops.gc_thresh = ~0;
2888         ip_rt_max_size = INT_MAX;
2889 
2890         devinet_init();
2891         ip_fib_init();
2892 
2893         if (ip_rt_proc_init())
2894                 pr_err("Unable to create route proc files\n");
2895 #ifdef CONFIG_XFRM
2896         xfrm_init();
2897         xfrm4_init();
2898 #endif
2899         rtnl_register(PF_INET, RTM_GETROUTE, inet_rtm_getroute, NULL, NULL);
2900 
2901 #ifdef CONFIG_SYSCTL
2902         register_pernet_subsys(&sysctl_route_ops);
2903 #endif
2904         register_pernet_subsys(&rt_genid_ops);
2905         register_pernet_subsys(&ipv4_inetpeer_ops);
2906         return rc;
2907 }
2908 
2909 #ifdef CONFIG_SYSCTL
2910 /*
2911  * We really need to sanitize the damn ipv4 init order, then all
2912  * this nonsense will go away.
2913  */
2914 void __init ip_static_sysctl_init(void)
2915 {
2916         register_net_sysctl(&init_net, "net/ipv4/route", ipv4_route_table);
2917 }
2918 #endif
2919 

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