Version:  2.0.40 2.2.26 2.4.37 3.4 3.5 3.6 3.7 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

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/net_namespace.h>
 95 #include <net/protocol.h>
 96 #include <net/ip.h>
 97 #include <net/route.h>
 98 #include <net/inetpeer.h>
 99 #include <net/sock.h>
100 #include <net/ip_fib.h>
101 #include <net/arp.h>
102 #include <net/tcp.h>
103 #include <net/icmp.h>
104 #include <net/xfrm.h>
105 #include <net/netevent.h>
106 #include <net/rtnetlink.h>
107 #ifdef CONFIG_SYSCTL
108 #include <linux/sysctl.h>
109 #include <linux/kmemleak.h>
110 #endif
111 #include <net/secure_seq.h>
112 
113 #define RT_FL_TOS(oldflp4) \
114         ((oldflp4)->flowi4_tos & (IPTOS_RT_MASK | RTO_ONLINK))
115 
116 #define RT_GC_TIMEOUT (300*HZ)
117 
118 static int ip_rt_max_size;
119 static int ip_rt_redirect_number __read_mostly  = 9;
120 static int ip_rt_redirect_load __read_mostly    = HZ / 50;
121 static int ip_rt_redirect_silence __read_mostly = ((HZ / 50) << (9 + 1));
122 static int ip_rt_error_cost __read_mostly       = HZ;
123 static int ip_rt_error_burst __read_mostly      = 5 * HZ;
124 static int ip_rt_mtu_expires __read_mostly      = 10 * 60 * HZ;
125 static int ip_rt_min_pmtu __read_mostly         = 512 + 20 + 20;
126 static int ip_rt_min_advmss __read_mostly       = 256;
127 
128 /*
129  *      Interface to generic destination cache.
130  */
131 
132 static struct dst_entry *ipv4_dst_check(struct dst_entry *dst, u32 cookie);
133 static unsigned int      ipv4_default_advmss(const struct dst_entry *dst);
134 static unsigned int      ipv4_mtu(const struct dst_entry *dst);
135 static struct dst_entry *ipv4_negative_advice(struct dst_entry *dst);
136 static void              ipv4_link_failure(struct sk_buff *skb);
137 static void              ip_rt_update_pmtu(struct dst_entry *dst, struct sock *sk,
138                                            struct sk_buff *skb, u32 mtu);
139 static void              ip_do_redirect(struct dst_entry *dst, struct sock *sk,
140                                         struct sk_buff *skb);
141 static void             ipv4_dst_destroy(struct dst_entry *dst);
142 
143 static u32 *ipv4_cow_metrics(struct dst_entry *dst, unsigned long old)
144 {
145         WARN_ON(1);
146         return NULL;
147 }
148 
149 static struct neighbour *ipv4_neigh_lookup(const struct dst_entry *dst,
150                                            struct sk_buff *skb,
151                                            const void *daddr);
152 
153 static struct dst_ops ipv4_dst_ops = {
154         .family =               AF_INET,
155         .protocol =             cpu_to_be16(ETH_P_IP),
156         .check =                ipv4_dst_check,
157         .default_advmss =       ipv4_default_advmss,
158         .mtu =                  ipv4_mtu,
159         .cow_metrics =          ipv4_cow_metrics,
160         .destroy =              ipv4_dst_destroy,
161         .negative_advice =      ipv4_negative_advice,
162         .link_failure =         ipv4_link_failure,
163         .update_pmtu =          ip_rt_update_pmtu,
164         .redirect =             ip_do_redirect,
165         .local_out =            __ip_local_out,
166         .neigh_lookup =         ipv4_neigh_lookup,
167 };
168 
169 #define ECN_OR_COST(class)      TC_PRIO_##class
170 
171 const __u8 ip_tos2prio[16] = {
172         TC_PRIO_BESTEFFORT,
173         ECN_OR_COST(BESTEFFORT),
174         TC_PRIO_BESTEFFORT,
175         ECN_OR_COST(BESTEFFORT),
176         TC_PRIO_BULK,
177         ECN_OR_COST(BULK),
178         TC_PRIO_BULK,
179         ECN_OR_COST(BULK),
180         TC_PRIO_INTERACTIVE,
181         ECN_OR_COST(INTERACTIVE),
182         TC_PRIO_INTERACTIVE,
183         ECN_OR_COST(INTERACTIVE),
184         TC_PRIO_INTERACTIVE_BULK,
185         ECN_OR_COST(INTERACTIVE_BULK),
186         TC_PRIO_INTERACTIVE_BULK,
187         ECN_OR_COST(INTERACTIVE_BULK)
188 };
189 EXPORT_SYMBOL(ip_tos2prio);
190 
191 static DEFINE_PER_CPU(struct rt_cache_stat, rt_cache_stat);
192 #define RT_CACHE_STAT_INC(field) raw_cpu_inc(rt_cache_stat.field)
193 
194 #ifdef CONFIG_PROC_FS
195 static void *rt_cache_seq_start(struct seq_file *seq, loff_t *pos)
196 {
197         if (*pos)
198                 return NULL;
199         return SEQ_START_TOKEN;
200 }
201 
202 static void *rt_cache_seq_next(struct seq_file *seq, void *v, loff_t *pos)
203 {
204         ++*pos;
205         return NULL;
206 }
207 
208 static void rt_cache_seq_stop(struct seq_file *seq, void *v)
209 {
210 }
211 
212 static int rt_cache_seq_show(struct seq_file *seq, void *v)
213 {
214         if (v == SEQ_START_TOKEN)
215                 seq_printf(seq, "%-127s\n",
216                            "Iface\tDestination\tGateway \tFlags\t\tRefCnt\tUse\t"
217                            "Metric\tSource\t\tMTU\tWindow\tIRTT\tTOS\tHHRef\t"
218                            "HHUptod\tSpecDst");
219         return 0;
220 }
221 
222 static const struct seq_operations rt_cache_seq_ops = {
223         .start  = rt_cache_seq_start,
224         .next   = rt_cache_seq_next,
225         .stop   = rt_cache_seq_stop,
226         .show   = rt_cache_seq_show,
227 };
228 
229 static int rt_cache_seq_open(struct inode *inode, struct file *file)
230 {
231         return seq_open(file, &rt_cache_seq_ops);
232 }
233 
234 static const struct file_operations rt_cache_seq_fops = {
235         .owner   = THIS_MODULE,
236         .open    = rt_cache_seq_open,
237         .read    = seq_read,
238         .llseek  = seq_lseek,
239         .release = seq_release,
240 };
241 
242 
243 static void *rt_cpu_seq_start(struct seq_file *seq, loff_t *pos)
244 {
245         int cpu;
246 
247         if (*pos == 0)
248                 return SEQ_START_TOKEN;
249 
250         for (cpu = *pos-1; cpu < nr_cpu_ids; ++cpu) {
251                 if (!cpu_possible(cpu))
252                         continue;
253                 *pos = cpu+1;
254                 return &per_cpu(rt_cache_stat, cpu);
255         }
256         return NULL;
257 }
258 
259 static void *rt_cpu_seq_next(struct seq_file *seq, void *v, loff_t *pos)
260 {
261         int cpu;
262 
263         for (cpu = *pos; cpu < nr_cpu_ids; ++cpu) {
264                 if (!cpu_possible(cpu))
265                         continue;
266                 *pos = cpu+1;
267                 return &per_cpu(rt_cache_stat, cpu);
268         }
269         return NULL;
270 
271 }
272 
273 static void rt_cpu_seq_stop(struct seq_file *seq, void *v)
274 {
275 
276 }
277 
278 static int rt_cpu_seq_show(struct seq_file *seq, void *v)
279 {
280         struct rt_cache_stat *st = v;
281 
282         if (v == SEQ_START_TOKEN) {
283                 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");
284                 return 0;
285         }
286 
287         seq_printf(seq,"%08x  %08x %08x %08x %08x %08x %08x %08x "
288                    " %08x %08x %08x %08x %08x %08x %08x %08x %08x \n",
289                    dst_entries_get_slow(&ipv4_dst_ops),
290                    0, /* st->in_hit */
291                    st->in_slow_tot,
292                    st->in_slow_mc,
293                    st->in_no_route,
294                    st->in_brd,
295                    st->in_martian_dst,
296                    st->in_martian_src,
297 
298                    0, /* st->out_hit */
299                    st->out_slow_tot,
300                    st->out_slow_mc,
301 
302                    0, /* st->gc_total */
303                    0, /* st->gc_ignored */
304                    0, /* st->gc_goal_miss */
305                    0, /* st->gc_dst_overflow */
306                    0, /* st->in_hlist_search */
307                    0  /* st->out_hlist_search */
308                 );
309         return 0;
310 }
311 
312 static const struct seq_operations rt_cpu_seq_ops = {
313         .start  = rt_cpu_seq_start,
314         .next   = rt_cpu_seq_next,
315         .stop   = rt_cpu_seq_stop,
316         .show   = rt_cpu_seq_show,
317 };
318 
319 
320 static int rt_cpu_seq_open(struct inode *inode, struct file *file)
321 {
322         return seq_open(file, &rt_cpu_seq_ops);
323 }
324 
325 static const struct file_operations rt_cpu_seq_fops = {
326         .owner   = THIS_MODULE,
327         .open    = rt_cpu_seq_open,
328         .read    = seq_read,
329         .llseek  = seq_lseek,
330         .release = seq_release,
331 };
332 
333 #ifdef CONFIG_IP_ROUTE_CLASSID
334 static int rt_acct_proc_show(struct seq_file *m, void *v)
335 {
336         struct ip_rt_acct *dst, *src;
337         unsigned int i, j;
338 
339         dst = kcalloc(256, sizeof(struct ip_rt_acct), GFP_KERNEL);
340         if (!dst)
341                 return -ENOMEM;
342 
343         for_each_possible_cpu(i) {
344                 src = (struct ip_rt_acct *)per_cpu_ptr(ip_rt_acct, i);
345                 for (j = 0; j < 256; j++) {
346                         dst[j].o_bytes   += src[j].o_bytes;
347                         dst[j].o_packets += src[j].o_packets;
348                         dst[j].i_bytes   += src[j].i_bytes;
349                         dst[j].i_packets += src[j].i_packets;
350                 }
351         }
352 
353         seq_write(m, dst, 256 * sizeof(struct ip_rt_acct));
354         kfree(dst);
355         return 0;
356 }
357 
358 static int rt_acct_proc_open(struct inode *inode, struct file *file)
359 {
360         return single_open(file, rt_acct_proc_show, NULL);
361 }
362 
363 static const struct file_operations rt_acct_proc_fops = {
364         .owner          = THIS_MODULE,
365         .open           = rt_acct_proc_open,
366         .read           = seq_read,
367         .llseek         = seq_lseek,
368         .release        = single_release,
369 };
370 #endif
371 
372 static int __net_init ip_rt_do_proc_init(struct net *net)
373 {
374         struct proc_dir_entry *pde;
375 
376         pde = proc_create("rt_cache", S_IRUGO, net->proc_net,
377                           &rt_cache_seq_fops);
378         if (!pde)
379                 goto err1;
380 
381         pde = proc_create("rt_cache", S_IRUGO,
382                           net->proc_net_stat, &rt_cpu_seq_fops);
383         if (!pde)
384                 goto err2;
385 
386 #ifdef CONFIG_IP_ROUTE_CLASSID
387         pde = proc_create("rt_acct", 0, net->proc_net, &rt_acct_proc_fops);
388         if (!pde)
389                 goto err3;
390 #endif
391         return 0;
392 
393 #ifdef CONFIG_IP_ROUTE_CLASSID
394 err3:
395         remove_proc_entry("rt_cache", net->proc_net_stat);
396 #endif
397 err2:
398         remove_proc_entry("rt_cache", net->proc_net);
399 err1:
400         return -ENOMEM;
401 }
402 
403 static void __net_exit ip_rt_do_proc_exit(struct net *net)
404 {
405         remove_proc_entry("rt_cache", net->proc_net_stat);
406         remove_proc_entry("rt_cache", net->proc_net);
407 #ifdef CONFIG_IP_ROUTE_CLASSID
408         remove_proc_entry("rt_acct", net->proc_net);
409 #endif
410 }
411 
412 static struct pernet_operations ip_rt_proc_ops __net_initdata =  {
413         .init = ip_rt_do_proc_init,
414         .exit = ip_rt_do_proc_exit,
415 };
416 
417 static int __init ip_rt_proc_init(void)
418 {
419         return register_pernet_subsys(&ip_rt_proc_ops);
420 }
421 
422 #else
423 static inline int ip_rt_proc_init(void)
424 {
425         return 0;
426 }
427 #endif /* CONFIG_PROC_FS */
428 
429 static inline bool rt_is_expired(const struct rtable *rth)
430 {
431         return rth->rt_genid != rt_genid_ipv4(dev_net(rth->dst.dev));
432 }
433 
434 void rt_cache_flush(struct net *net)
435 {
436         rt_genid_bump_ipv4(net);
437 }
438 
439 static struct neighbour *ipv4_neigh_lookup(const struct dst_entry *dst,
440                                            struct sk_buff *skb,
441                                            const void *daddr)
442 {
443         struct net_device *dev = dst->dev;
444         const __be32 *pkey = daddr;
445         const struct rtable *rt;
446         struct neighbour *n;
447 
448         rt = (const struct rtable *) dst;
449         if (rt->rt_gateway)
450                 pkey = (const __be32 *) &rt->rt_gateway;
451         else if (skb)
452                 pkey = &ip_hdr(skb)->daddr;
453 
454         n = __ipv4_neigh_lookup(dev, *(__force u32 *)pkey);
455         if (n)
456                 return n;
457         return neigh_create(&arp_tbl, pkey, dev);
458 }
459 
460 #define IP_IDENTS_SZ 2048u
461 struct ip_ident_bucket {
462         atomic_t        id;
463         u32             stamp32;
464 };
465 
466 static struct ip_ident_bucket *ip_idents __read_mostly;
467 
468 /* In order to protect privacy, we add a perturbation to identifiers
469  * if one generator is seldom used. This makes hard for an attacker
470  * to infer how many packets were sent between two points in time.
471  */
472 u32 ip_idents_reserve(u32 hash, int segs)
473 {
474         struct ip_ident_bucket *bucket = ip_idents + hash % IP_IDENTS_SZ;
475         u32 old = ACCESS_ONCE(bucket->stamp32);
476         u32 now = (u32)jiffies;
477         u32 delta = 0;
478 
479         if (old != now && cmpxchg(&bucket->stamp32, old, now) == old)
480                 delta = prandom_u32_max(now - old);
481 
482         return atomic_add_return(segs + delta, &bucket->id) - segs;
483 }
484 EXPORT_SYMBOL(ip_idents_reserve);
485 
486 void __ip_select_ident(struct iphdr *iph, int segs)
487 {
488         static u32 ip_idents_hashrnd __read_mostly;
489         u32 hash, id;
490 
491         net_get_random_once(&ip_idents_hashrnd, sizeof(ip_idents_hashrnd));
492 
493         hash = jhash_3words((__force u32)iph->daddr,
494                             (__force u32)iph->saddr,
495                             iph->protocol,
496                             ip_idents_hashrnd);
497         id = ip_idents_reserve(hash, segs);
498         iph->id = htons(id);
499 }
500 EXPORT_SYMBOL(__ip_select_ident);
501 
502 static void __build_flow_key(struct flowi4 *fl4, const struct sock *sk,
503                              const struct iphdr *iph,
504                              int oif, u8 tos,
505                              u8 prot, u32 mark, int flow_flags)
506 {
507         if (sk) {
508                 const struct inet_sock *inet = inet_sk(sk);
509 
510                 oif = sk->sk_bound_dev_if;
511                 mark = sk->sk_mark;
512                 tos = RT_CONN_FLAGS(sk);
513                 prot = inet->hdrincl ? IPPROTO_RAW : sk->sk_protocol;
514         }
515         flowi4_init_output(fl4, oif, mark, tos,
516                            RT_SCOPE_UNIVERSE, prot,
517                            flow_flags,
518                            iph->daddr, iph->saddr, 0, 0);
519 }
520 
521 static void build_skb_flow_key(struct flowi4 *fl4, const struct sk_buff *skb,
522                                const struct sock *sk)
523 {
524         const struct iphdr *iph = ip_hdr(skb);
525         int oif = skb->dev->ifindex;
526         u8 tos = RT_TOS(iph->tos);
527         u8 prot = iph->protocol;
528         u32 mark = skb->mark;
529 
530         __build_flow_key(fl4, sk, iph, oif, tos, prot, mark, 0);
531 }
532 
533 static void build_sk_flow_key(struct flowi4 *fl4, const struct sock *sk)
534 {
535         const struct inet_sock *inet = inet_sk(sk);
536         const struct ip_options_rcu *inet_opt;
537         __be32 daddr = inet->inet_daddr;
538 
539         rcu_read_lock();
540         inet_opt = rcu_dereference(inet->inet_opt);
541         if (inet_opt && inet_opt->opt.srr)
542                 daddr = inet_opt->opt.faddr;
543         flowi4_init_output(fl4, sk->sk_bound_dev_if, sk->sk_mark,
544                            RT_CONN_FLAGS(sk), RT_SCOPE_UNIVERSE,
545                            inet->hdrincl ? IPPROTO_RAW : sk->sk_protocol,
546                            inet_sk_flowi_flags(sk),
547                            daddr, inet->inet_saddr, 0, 0);
548         rcu_read_unlock();
549 }
550 
551 static void ip_rt_build_flow_key(struct flowi4 *fl4, const struct sock *sk,
552                                  const struct sk_buff *skb)
553 {
554         if (skb)
555                 build_skb_flow_key(fl4, skb, sk);
556         else
557                 build_sk_flow_key(fl4, sk);
558 }
559 
560 static inline void rt_free(struct rtable *rt)
561 {
562         call_rcu(&rt->dst.rcu_head, dst_rcu_free);
563 }
564 
565 static DEFINE_SPINLOCK(fnhe_lock);
566 
567 static void fnhe_flush_routes(struct fib_nh_exception *fnhe)
568 {
569         struct rtable *rt;
570 
571         rt = rcu_dereference(fnhe->fnhe_rth_input);
572         if (rt) {
573                 RCU_INIT_POINTER(fnhe->fnhe_rth_input, NULL);
574                 rt_free(rt);
575         }
576         rt = rcu_dereference(fnhe->fnhe_rth_output);
577         if (rt) {
578                 RCU_INIT_POINTER(fnhe->fnhe_rth_output, NULL);
579                 rt_free(rt);
580         }
581 }
582 
583 static struct fib_nh_exception *fnhe_oldest(struct fnhe_hash_bucket *hash)
584 {
585         struct fib_nh_exception *fnhe, *oldest;
586 
587         oldest = rcu_dereference(hash->chain);
588         for (fnhe = rcu_dereference(oldest->fnhe_next); fnhe;
589              fnhe = rcu_dereference(fnhe->fnhe_next)) {
590                 if (time_before(fnhe->fnhe_stamp, oldest->fnhe_stamp))
591                         oldest = fnhe;
592         }
593         fnhe_flush_routes(oldest);
594         return oldest;
595 }
596 
597 static inline u32 fnhe_hashfun(__be32 daddr)
598 {
599         static u32 fnhe_hashrnd __read_mostly;
600         u32 hval;
601 
602         net_get_random_once(&fnhe_hashrnd, sizeof(fnhe_hashrnd));
603         hval = jhash_1word((__force u32) daddr, fnhe_hashrnd);
604         return hash_32(hval, FNHE_HASH_SHIFT);
605 }
606 
607 static void fill_route_from_fnhe(struct rtable *rt, struct fib_nh_exception *fnhe)
608 {
609         rt->rt_pmtu = fnhe->fnhe_pmtu;
610         rt->dst.expires = fnhe->fnhe_expires;
611 
612         if (fnhe->fnhe_gw) {
613                 rt->rt_flags |= RTCF_REDIRECTED;
614                 rt->rt_gateway = fnhe->fnhe_gw;
615                 rt->rt_uses_gateway = 1;
616         }
617 }
618 
619 static void update_or_create_fnhe(struct fib_nh *nh, __be32 daddr, __be32 gw,
620                                   u32 pmtu, unsigned long expires)
621 {
622         struct fnhe_hash_bucket *hash;
623         struct fib_nh_exception *fnhe;
624         struct rtable *rt;
625         unsigned int i;
626         int depth;
627         u32 hval = fnhe_hashfun(daddr);
628 
629         spin_lock_bh(&fnhe_lock);
630 
631         hash = rcu_dereference(nh->nh_exceptions);
632         if (!hash) {
633                 hash = kzalloc(FNHE_HASH_SIZE * sizeof(*hash), GFP_ATOMIC);
634                 if (!hash)
635                         goto out_unlock;
636                 rcu_assign_pointer(nh->nh_exceptions, hash);
637         }
638 
639         hash += hval;
640 
641         depth = 0;
642         for (fnhe = rcu_dereference(hash->chain); fnhe;
643              fnhe = rcu_dereference(fnhe->fnhe_next)) {
644                 if (fnhe->fnhe_daddr == daddr)
645                         break;
646                 depth++;
647         }
648 
649         if (fnhe) {
650                 if (gw)
651                         fnhe->fnhe_gw = gw;
652                 if (pmtu) {
653                         fnhe->fnhe_pmtu = pmtu;
654                         fnhe->fnhe_expires = max(1UL, expires);
655                 }
656                 /* Update all cached dsts too */
657                 rt = rcu_dereference(fnhe->fnhe_rth_input);
658                 if (rt)
659                         fill_route_from_fnhe(rt, fnhe);
660                 rt = rcu_dereference(fnhe->fnhe_rth_output);
661                 if (rt)
662                         fill_route_from_fnhe(rt, fnhe);
663         } else {
664                 if (depth > FNHE_RECLAIM_DEPTH)
665                         fnhe = fnhe_oldest(hash);
666                 else {
667                         fnhe = kzalloc(sizeof(*fnhe), GFP_ATOMIC);
668                         if (!fnhe)
669                                 goto out_unlock;
670 
671                         fnhe->fnhe_next = hash->chain;
672                         rcu_assign_pointer(hash->chain, fnhe);
673                 }
674                 fnhe->fnhe_genid = fnhe_genid(dev_net(nh->nh_dev));
675                 fnhe->fnhe_daddr = daddr;
676                 fnhe->fnhe_gw = gw;
677                 fnhe->fnhe_pmtu = pmtu;
678                 fnhe->fnhe_expires = expires;
679 
680                 /* Exception created; mark the cached routes for the nexthop
681                  * stale, so anyone caching it rechecks if this exception
682                  * applies to them.
683                  */
684                 rt = rcu_dereference(nh->nh_rth_input);
685                 if (rt)
686                         rt->dst.obsolete = DST_OBSOLETE_KILL;
687 
688                 for_each_possible_cpu(i) {
689                         struct rtable __rcu **prt;
690                         prt = per_cpu_ptr(nh->nh_pcpu_rth_output, i);
691                         rt = rcu_dereference(*prt);
692                         if (rt)
693                                 rt->dst.obsolete = DST_OBSOLETE_KILL;
694                 }
695         }
696 
697         fnhe->fnhe_stamp = jiffies;
698 
699 out_unlock:
700         spin_unlock_bh(&fnhe_lock);
701 }
702 
703 static void __ip_do_redirect(struct rtable *rt, struct sk_buff *skb, struct flowi4 *fl4,
704                              bool kill_route)
705 {
706         __be32 new_gw = icmp_hdr(skb)->un.gateway;
707         __be32 old_gw = ip_hdr(skb)->saddr;
708         struct net_device *dev = skb->dev;
709         struct in_device *in_dev;
710         struct fib_result res;
711         struct neighbour *n;
712         struct net *net;
713 
714         switch (icmp_hdr(skb)->code & 7) {
715         case ICMP_REDIR_NET:
716         case ICMP_REDIR_NETTOS:
717         case ICMP_REDIR_HOST:
718         case ICMP_REDIR_HOSTTOS:
719                 break;
720 
721         default:
722                 return;
723         }
724 
725         if (rt->rt_gateway != old_gw)
726                 return;
727 
728         in_dev = __in_dev_get_rcu(dev);
729         if (!in_dev)
730                 return;
731 
732         net = dev_net(dev);
733         if (new_gw == old_gw || !IN_DEV_RX_REDIRECTS(in_dev) ||
734             ipv4_is_multicast(new_gw) || ipv4_is_lbcast(new_gw) ||
735             ipv4_is_zeronet(new_gw))
736                 goto reject_redirect;
737 
738         if (!IN_DEV_SHARED_MEDIA(in_dev)) {
739                 if (!inet_addr_onlink(in_dev, new_gw, old_gw))
740                         goto reject_redirect;
741                 if (IN_DEV_SEC_REDIRECTS(in_dev) && ip_fib_check_default(new_gw, dev))
742                         goto reject_redirect;
743         } else {
744                 if (inet_addr_type(net, new_gw) != RTN_UNICAST)
745                         goto reject_redirect;
746         }
747 
748         n = ipv4_neigh_lookup(&rt->dst, NULL, &new_gw);
749         if (!IS_ERR(n)) {
750                 if (!(n->nud_state & NUD_VALID)) {
751                         neigh_event_send(n, NULL);
752                 } else {
753                         if (fib_lookup(net, fl4, &res) == 0) {
754                                 struct fib_nh *nh = &FIB_RES_NH(res);
755 
756                                 update_or_create_fnhe(nh, fl4->daddr, new_gw,
757                                                       0, 0);
758                         }
759                         if (kill_route)
760                                 rt->dst.obsolete = DST_OBSOLETE_KILL;
761                         call_netevent_notifiers(NETEVENT_NEIGH_UPDATE, n);
762                 }
763                 neigh_release(n);
764         }
765         return;
766 
767 reject_redirect:
768 #ifdef CONFIG_IP_ROUTE_VERBOSE
769         if (IN_DEV_LOG_MARTIANS(in_dev)) {
770                 const struct iphdr *iph = (const struct iphdr *) skb->data;
771                 __be32 daddr = iph->daddr;
772                 __be32 saddr = iph->saddr;
773 
774                 net_info_ratelimited("Redirect from %pI4 on %s about %pI4 ignored\n"
775                                      "  Advised path = %pI4 -> %pI4\n",
776                                      &old_gw, dev->name, &new_gw,
777                                      &saddr, &daddr);
778         }
779 #endif
780         ;
781 }
782 
783 static void ip_do_redirect(struct dst_entry *dst, struct sock *sk, struct sk_buff *skb)
784 {
785         struct rtable *rt;
786         struct flowi4 fl4;
787         const struct iphdr *iph = (const struct iphdr *) skb->data;
788         int oif = skb->dev->ifindex;
789         u8 tos = RT_TOS(iph->tos);
790         u8 prot = iph->protocol;
791         u32 mark = skb->mark;
792 
793         rt = (struct rtable *) dst;
794 
795         __build_flow_key(&fl4, sk, iph, oif, tos, prot, mark, 0);
796         __ip_do_redirect(rt, skb, &fl4, true);
797 }
798 
799 static struct dst_entry *ipv4_negative_advice(struct dst_entry *dst)
800 {
801         struct rtable *rt = (struct rtable *)dst;
802         struct dst_entry *ret = dst;
803 
804         if (rt) {
805                 if (dst->obsolete > 0) {
806                         ip_rt_put(rt);
807                         ret = NULL;
808                 } else if ((rt->rt_flags & RTCF_REDIRECTED) ||
809                            rt->dst.expires) {
810                         ip_rt_put(rt);
811                         ret = NULL;
812                 }
813         }
814         return ret;
815 }
816 
817 /*
818  * Algorithm:
819  *      1. The first ip_rt_redirect_number redirects are sent
820  *         with exponential backoff, then we stop sending them at all,
821  *         assuming that the host ignores our redirects.
822  *      2. If we did not see packets requiring redirects
823  *         during ip_rt_redirect_silence, we assume that the host
824  *         forgot redirected route and start to send redirects again.
825  *
826  * This algorithm is much cheaper and more intelligent than dumb load limiting
827  * in icmp.c.
828  *
829  * NOTE. Do not forget to inhibit load limiting for redirects (redundant)
830  * and "frag. need" (breaks PMTU discovery) in icmp.c.
831  */
832 
833 void ip_rt_send_redirect(struct sk_buff *skb)
834 {
835         struct rtable *rt = skb_rtable(skb);
836         struct in_device *in_dev;
837         struct inet_peer *peer;
838         struct net *net;
839         int log_martians;
840 
841         rcu_read_lock();
842         in_dev = __in_dev_get_rcu(rt->dst.dev);
843         if (!in_dev || !IN_DEV_TX_REDIRECTS(in_dev)) {
844                 rcu_read_unlock();
845                 return;
846         }
847         log_martians = IN_DEV_LOG_MARTIANS(in_dev);
848         rcu_read_unlock();
849 
850         net = dev_net(rt->dst.dev);
851         peer = inet_getpeer_v4(net->ipv4.peers, ip_hdr(skb)->saddr, 1);
852         if (!peer) {
853                 icmp_send(skb, ICMP_REDIRECT, ICMP_REDIR_HOST,
854                           rt_nexthop(rt, ip_hdr(skb)->daddr));
855                 return;
856         }
857 
858         /* No redirected packets during ip_rt_redirect_silence;
859          * reset the algorithm.
860          */
861         if (time_after(jiffies, peer->rate_last + ip_rt_redirect_silence))
862                 peer->rate_tokens = 0;
863 
864         /* Too many ignored redirects; do not send anything
865          * set dst.rate_last to the last seen redirected packet.
866          */
867         if (peer->rate_tokens >= ip_rt_redirect_number) {
868                 peer->rate_last = jiffies;
869                 goto out_put_peer;
870         }
871 
872         /* Check for load limit; set rate_last to the latest sent
873          * redirect.
874          */
875         if (peer->rate_tokens == 0 ||
876             time_after(jiffies,
877                        (peer->rate_last +
878                         (ip_rt_redirect_load << peer->rate_tokens)))) {
879                 __be32 gw = rt_nexthop(rt, ip_hdr(skb)->daddr);
880 
881                 icmp_send(skb, ICMP_REDIRECT, ICMP_REDIR_HOST, gw);
882                 peer->rate_last = jiffies;
883                 ++peer->rate_tokens;
884 #ifdef CONFIG_IP_ROUTE_VERBOSE
885                 if (log_martians &&
886                     peer->rate_tokens == ip_rt_redirect_number)
887                         net_warn_ratelimited("host %pI4/if%d ignores redirects for %pI4 to %pI4\n",
888                                              &ip_hdr(skb)->saddr, inet_iif(skb),
889                                              &ip_hdr(skb)->daddr, &gw);
890 #endif
891         }
892 out_put_peer:
893         inet_putpeer(peer);
894 }
895 
896 static int ip_error(struct sk_buff *skb)
897 {
898         struct in_device *in_dev = __in_dev_get_rcu(skb->dev);
899         struct rtable *rt = skb_rtable(skb);
900         struct inet_peer *peer;
901         unsigned long now;
902         struct net *net;
903         bool send;
904         int code;
905 
906         net = dev_net(rt->dst.dev);
907         if (!IN_DEV_FORWARD(in_dev)) {
908                 switch (rt->dst.error) {
909                 case EHOSTUNREACH:
910                         IP_INC_STATS_BH(net, IPSTATS_MIB_INADDRERRORS);
911                         break;
912 
913                 case ENETUNREACH:
914                         IP_INC_STATS_BH(net, IPSTATS_MIB_INNOROUTES);
915                         break;
916                 }
917                 goto out;
918         }
919 
920         switch (rt->dst.error) {
921         case EINVAL:
922         default:
923                 goto out;
924         case EHOSTUNREACH:
925                 code = ICMP_HOST_UNREACH;
926                 break;
927         case ENETUNREACH:
928                 code = ICMP_NET_UNREACH;
929                 IP_INC_STATS_BH(net, IPSTATS_MIB_INNOROUTES);
930                 break;
931         case EACCES:
932                 code = ICMP_PKT_FILTERED;
933                 break;
934         }
935 
936         peer = inet_getpeer_v4(net->ipv4.peers, ip_hdr(skb)->saddr, 1);
937 
938         send = true;
939         if (peer) {
940                 now = jiffies;
941                 peer->rate_tokens += now - peer->rate_last;
942                 if (peer->rate_tokens > ip_rt_error_burst)
943                         peer->rate_tokens = ip_rt_error_burst;
944                 peer->rate_last = now;
945                 if (peer->rate_tokens >= ip_rt_error_cost)
946                         peer->rate_tokens -= ip_rt_error_cost;
947                 else
948                         send = false;
949                 inet_putpeer(peer);
950         }
951         if (send)
952                 icmp_send(skb, ICMP_DEST_UNREACH, code, 0);
953 
954 out:    kfree_skb(skb);
955         return 0;
956 }
957 
958 static void __ip_rt_update_pmtu(struct rtable *rt, struct flowi4 *fl4, u32 mtu)
959 {
960         struct dst_entry *dst = &rt->dst;
961         struct fib_result res;
962 
963         if (dst_metric_locked(dst, RTAX_MTU))
964                 return;
965 
966         if (dst->dev->mtu < mtu)
967                 return;
968 
969         if (rt->rt_pmtu && rt->rt_pmtu < mtu)
970                 return;
971 
972         if (mtu < ip_rt_min_pmtu)
973                 mtu = ip_rt_min_pmtu;
974 
975         if (rt->rt_pmtu == mtu &&
976             time_before(jiffies, dst->expires - ip_rt_mtu_expires / 2))
977                 return;
978 
979         rcu_read_lock();
980         if (fib_lookup(dev_net(dst->dev), fl4, &res) == 0) {
981                 struct fib_nh *nh = &FIB_RES_NH(res);
982 
983                 update_or_create_fnhe(nh, fl4->daddr, 0, mtu,
984                                       jiffies + ip_rt_mtu_expires);
985         }
986         rcu_read_unlock();
987 }
988 
989 static void ip_rt_update_pmtu(struct dst_entry *dst, struct sock *sk,
990                               struct sk_buff *skb, u32 mtu)
991 {
992         struct rtable *rt = (struct rtable *) dst;
993         struct flowi4 fl4;
994 
995         ip_rt_build_flow_key(&fl4, sk, skb);
996         __ip_rt_update_pmtu(rt, &fl4, mtu);
997 }
998 
999 void ipv4_update_pmtu(struct sk_buff *skb, struct net *net, u32 mtu,
1000                       int oif, u32 mark, u8 protocol, int flow_flags)
1001 {
1002         const struct iphdr *iph = (const struct iphdr *) skb->data;
1003         struct flowi4 fl4;
1004         struct rtable *rt;
1005 
1006         if (!mark)
1007                 mark = IP4_REPLY_MARK(net, skb->mark);
1008 
1009         __build_flow_key(&fl4, NULL, iph, oif,
1010                          RT_TOS(iph->tos), protocol, mark, flow_flags);
1011         rt = __ip_route_output_key(net, &fl4);
1012         if (!IS_ERR(rt)) {
1013                 __ip_rt_update_pmtu(rt, &fl4, mtu);
1014                 ip_rt_put(rt);
1015         }
1016 }
1017 EXPORT_SYMBOL_GPL(ipv4_update_pmtu);
1018 
1019 static void __ipv4_sk_update_pmtu(struct sk_buff *skb, struct sock *sk, u32 mtu)
1020 {
1021         const struct iphdr *iph = (const struct iphdr *) skb->data;
1022         struct flowi4 fl4;
1023         struct rtable *rt;
1024 
1025         __build_flow_key(&fl4, sk, iph, 0, 0, 0, 0, 0);
1026 
1027         if (!fl4.flowi4_mark)
1028                 fl4.flowi4_mark = IP4_REPLY_MARK(sock_net(sk), skb->mark);
1029 
1030         rt = __ip_route_output_key(sock_net(sk), &fl4);
1031         if (!IS_ERR(rt)) {
1032                 __ip_rt_update_pmtu(rt, &fl4, mtu);
1033                 ip_rt_put(rt);
1034         }
1035 }
1036 
1037 void ipv4_sk_update_pmtu(struct sk_buff *skb, struct sock *sk, u32 mtu)
1038 {
1039         const struct iphdr *iph = (const struct iphdr *) skb->data;
1040         struct flowi4 fl4;
1041         struct rtable *rt;
1042         struct dst_entry *odst = NULL;
1043         bool new = false;
1044 
1045         bh_lock_sock(sk);
1046 
1047         if (!ip_sk_accept_pmtu(sk))
1048                 goto out;
1049 
1050         odst = sk_dst_get(sk);
1051 
1052         if (sock_owned_by_user(sk) || !odst) {
1053                 __ipv4_sk_update_pmtu(skb, sk, mtu);
1054                 goto out;
1055         }
1056 
1057         __build_flow_key(&fl4, sk, iph, 0, 0, 0, 0, 0);
1058 
1059         rt = (struct rtable *)odst;
1060         if (odst->obsolete && odst->ops->check(odst, 0) == NULL) {
1061                 rt = ip_route_output_flow(sock_net(sk), &fl4, sk);
1062                 if (IS_ERR(rt))
1063                         goto out;
1064 
1065                 new = true;
1066         }
1067 
1068         __ip_rt_update_pmtu((struct rtable *) rt->dst.path, &fl4, mtu);
1069 
1070         if (!dst_check(&rt->dst, 0)) {
1071                 if (new)
1072                         dst_release(&rt->dst);
1073 
1074                 rt = ip_route_output_flow(sock_net(sk), &fl4, sk);
1075                 if (IS_ERR(rt))
1076                         goto out;
1077 
1078                 new = true;
1079         }
1080 
1081         if (new)
1082                 sk_dst_set(sk, &rt->dst);
1083 
1084 out:
1085         bh_unlock_sock(sk);
1086         dst_release(odst);
1087 }
1088 EXPORT_SYMBOL_GPL(ipv4_sk_update_pmtu);
1089 
1090 void ipv4_redirect(struct sk_buff *skb, struct net *net,
1091                    int oif, u32 mark, u8 protocol, int flow_flags)
1092 {
1093         const struct iphdr *iph = (const struct iphdr *) skb->data;
1094         struct flowi4 fl4;
1095         struct rtable *rt;
1096 
1097         __build_flow_key(&fl4, NULL, iph, oif,
1098                          RT_TOS(iph->tos), protocol, mark, flow_flags);
1099         rt = __ip_route_output_key(net, &fl4);
1100         if (!IS_ERR(rt)) {
1101                 __ip_do_redirect(rt, skb, &fl4, false);
1102                 ip_rt_put(rt);
1103         }
1104 }
1105 EXPORT_SYMBOL_GPL(ipv4_redirect);
1106 
1107 void ipv4_sk_redirect(struct sk_buff *skb, struct sock *sk)
1108 {
1109         const struct iphdr *iph = (const struct iphdr *) skb->data;
1110         struct flowi4 fl4;
1111         struct rtable *rt;
1112 
1113         __build_flow_key(&fl4, sk, iph, 0, 0, 0, 0, 0);
1114         rt = __ip_route_output_key(sock_net(sk), &fl4);
1115         if (!IS_ERR(rt)) {
1116                 __ip_do_redirect(rt, skb, &fl4, false);
1117                 ip_rt_put(rt);
1118         }
1119 }
1120 EXPORT_SYMBOL_GPL(ipv4_sk_redirect);
1121 
1122 static struct dst_entry *ipv4_dst_check(struct dst_entry *dst, u32 cookie)
1123 {
1124         struct rtable *rt = (struct rtable *) dst;
1125 
1126         /* All IPV4 dsts are created with ->obsolete set to the value
1127          * DST_OBSOLETE_FORCE_CHK which forces validation calls down
1128          * into this function always.
1129          *
1130          * When a PMTU/redirect information update invalidates a route,
1131          * this is indicated by setting obsolete to DST_OBSOLETE_KILL or
1132          * DST_OBSOLETE_DEAD by dst_free().
1133          */
1134         if (dst->obsolete != DST_OBSOLETE_FORCE_CHK || rt_is_expired(rt))
1135                 return NULL;
1136         return dst;
1137 }
1138 
1139 static void ipv4_link_failure(struct sk_buff *skb)
1140 {
1141         struct rtable *rt;
1142 
1143         icmp_send(skb, ICMP_DEST_UNREACH, ICMP_HOST_UNREACH, 0);
1144 
1145         rt = skb_rtable(skb);
1146         if (rt)
1147                 dst_set_expires(&rt->dst, 0);
1148 }
1149 
1150 static int ip_rt_bug(struct sock *sk, struct sk_buff *skb)
1151 {
1152         pr_debug("%s: %pI4 -> %pI4, %s\n",
1153                  __func__, &ip_hdr(skb)->saddr, &ip_hdr(skb)->daddr,
1154                  skb->dev ? skb->dev->name : "?");
1155         kfree_skb(skb);
1156         WARN_ON(1);
1157         return 0;
1158 }
1159 
1160 /*
1161    We do not cache source address of outgoing interface,
1162    because it is used only by IP RR, TS and SRR options,
1163    so that it out of fast path.
1164 
1165    BTW remember: "addr" is allowed to be not aligned
1166    in IP options!
1167  */
1168 
1169 void ip_rt_get_source(u8 *addr, struct sk_buff *skb, struct rtable *rt)
1170 {
1171         __be32 src;
1172 
1173         if (rt_is_output_route(rt))
1174                 src = ip_hdr(skb)->saddr;
1175         else {
1176                 struct fib_result res;
1177                 struct flowi4 fl4;
1178                 struct iphdr *iph;
1179 
1180                 iph = ip_hdr(skb);
1181 
1182                 memset(&fl4, 0, sizeof(fl4));
1183                 fl4.daddr = iph->daddr;
1184                 fl4.saddr = iph->saddr;
1185                 fl4.flowi4_tos = RT_TOS(iph->tos);
1186                 fl4.flowi4_oif = rt->dst.dev->ifindex;
1187                 fl4.flowi4_iif = skb->dev->ifindex;
1188                 fl4.flowi4_mark = skb->mark;
1189 
1190                 rcu_read_lock();
1191                 if (fib_lookup(dev_net(rt->dst.dev), &fl4, &res) == 0)
1192                         src = FIB_RES_PREFSRC(dev_net(rt->dst.dev), res);
1193                 else
1194                         src = inet_select_addr(rt->dst.dev,
1195                                                rt_nexthop(rt, iph->daddr),
1196                                                RT_SCOPE_UNIVERSE);
1197                 rcu_read_unlock();
1198         }
1199         memcpy(addr, &src, 4);
1200 }
1201 
1202 #ifdef CONFIG_IP_ROUTE_CLASSID
1203 static void set_class_tag(struct rtable *rt, u32 tag)
1204 {
1205         if (!(rt->dst.tclassid & 0xFFFF))
1206                 rt->dst.tclassid |= tag & 0xFFFF;
1207         if (!(rt->dst.tclassid & 0xFFFF0000))
1208                 rt->dst.tclassid |= tag & 0xFFFF0000;
1209 }
1210 #endif
1211 
1212 static unsigned int ipv4_default_advmss(const struct dst_entry *dst)
1213 {
1214         unsigned int advmss = dst_metric_raw(dst, RTAX_ADVMSS);
1215 
1216         if (advmss == 0) {
1217                 advmss = max_t(unsigned int, dst->dev->mtu - 40,
1218                                ip_rt_min_advmss);
1219                 if (advmss > 65535 - 40)
1220                         advmss = 65535 - 40;
1221         }
1222         return advmss;
1223 }
1224 
1225 static unsigned int ipv4_mtu(const struct dst_entry *dst)
1226 {
1227         const struct rtable *rt = (const struct rtable *) dst;
1228         unsigned int mtu = rt->rt_pmtu;
1229 
1230         if (!mtu || time_after_eq(jiffies, rt->dst.expires))
1231                 mtu = dst_metric_raw(dst, RTAX_MTU);
1232 
1233         if (mtu)
1234                 return mtu;
1235 
1236         mtu = dst->dev->mtu;
1237 
1238         if (unlikely(dst_metric_locked(dst, RTAX_MTU))) {
1239                 if (rt->rt_uses_gateway && mtu > 576)
1240                         mtu = 576;
1241         }
1242 
1243         return min_t(unsigned int, mtu, IP_MAX_MTU);
1244 }
1245 
1246 static struct fib_nh_exception *find_exception(struct fib_nh *nh, __be32 daddr)
1247 {
1248         struct fnhe_hash_bucket *hash = rcu_dereference(nh->nh_exceptions);
1249         struct fib_nh_exception *fnhe;
1250         u32 hval;
1251 
1252         if (!hash)
1253                 return NULL;
1254 
1255         hval = fnhe_hashfun(daddr);
1256 
1257         for (fnhe = rcu_dereference(hash[hval].chain); fnhe;
1258              fnhe = rcu_dereference(fnhe->fnhe_next)) {
1259                 if (fnhe->fnhe_daddr == daddr)
1260                         return fnhe;
1261         }
1262         return NULL;
1263 }
1264 
1265 static bool rt_bind_exception(struct rtable *rt, struct fib_nh_exception *fnhe,
1266                               __be32 daddr)
1267 {
1268         bool ret = false;
1269 
1270         spin_lock_bh(&fnhe_lock);
1271 
1272         if (daddr == fnhe->fnhe_daddr) {
1273                 struct rtable __rcu **porig;
1274                 struct rtable *orig;
1275                 int genid = fnhe_genid(dev_net(rt->dst.dev));
1276 
1277                 if (rt_is_input_route(rt))
1278                         porig = &fnhe->fnhe_rth_input;
1279                 else
1280                         porig = &fnhe->fnhe_rth_output;
1281                 orig = rcu_dereference(*porig);
1282 
1283                 if (fnhe->fnhe_genid != genid) {
1284                         fnhe->fnhe_genid = genid;
1285                         fnhe->fnhe_gw = 0;
1286                         fnhe->fnhe_pmtu = 0;
1287                         fnhe->fnhe_expires = 0;
1288                         fnhe_flush_routes(fnhe);
1289                         orig = NULL;
1290                 }
1291                 fill_route_from_fnhe(rt, fnhe);
1292                 if (!rt->rt_gateway)
1293                         rt->rt_gateway = daddr;
1294 
1295                 if (!(rt->dst.flags & DST_NOCACHE)) {
1296                         rcu_assign_pointer(*porig, rt);
1297                         if (orig)
1298                                 rt_free(orig);
1299                         ret = true;
1300                 }
1301 
1302                 fnhe->fnhe_stamp = jiffies;
1303         }
1304         spin_unlock_bh(&fnhe_lock);
1305 
1306         return ret;
1307 }
1308 
1309 static bool rt_cache_route(struct fib_nh *nh, struct rtable *rt)
1310 {
1311         struct rtable *orig, *prev, **p;
1312         bool ret = true;
1313 
1314         if (rt_is_input_route(rt)) {
1315                 p = (struct rtable **)&nh->nh_rth_input;
1316         } else {
1317                 p = (struct rtable **)raw_cpu_ptr(nh->nh_pcpu_rth_output);
1318         }
1319         orig = *p;
1320 
1321         prev = cmpxchg(p, orig, rt);
1322         if (prev == orig) {
1323                 if (orig)
1324                         rt_free(orig);
1325         } else
1326                 ret = false;
1327 
1328         return ret;
1329 }
1330 
1331 struct uncached_list {
1332         spinlock_t              lock;
1333         struct list_head        head;
1334 };
1335 
1336 static DEFINE_PER_CPU_ALIGNED(struct uncached_list, rt_uncached_list);
1337 
1338 static void rt_add_uncached_list(struct rtable *rt)
1339 {
1340         struct uncached_list *ul = raw_cpu_ptr(&rt_uncached_list);
1341 
1342         rt->rt_uncached_list = ul;
1343 
1344         spin_lock_bh(&ul->lock);
1345         list_add_tail(&rt->rt_uncached, &ul->head);
1346         spin_unlock_bh(&ul->lock);
1347 }
1348 
1349 static void ipv4_dst_destroy(struct dst_entry *dst)
1350 {
1351         struct rtable *rt = (struct rtable *) dst;
1352 
1353         if (!list_empty(&rt->rt_uncached)) {
1354                 struct uncached_list *ul = rt->rt_uncached_list;
1355 
1356                 spin_lock_bh(&ul->lock);
1357                 list_del(&rt->rt_uncached);
1358                 spin_unlock_bh(&ul->lock);
1359         }
1360 }
1361 
1362 void rt_flush_dev(struct net_device *dev)
1363 {
1364         struct net *net = dev_net(dev);
1365         struct rtable *rt;
1366         int cpu;
1367 
1368         for_each_possible_cpu(cpu) {
1369                 struct uncached_list *ul = &per_cpu(rt_uncached_list, cpu);
1370 
1371                 spin_lock_bh(&ul->lock);
1372                 list_for_each_entry(rt, &ul->head, rt_uncached) {
1373                         if (rt->dst.dev != dev)
1374                                 continue;
1375                         rt->dst.dev = net->loopback_dev;
1376                         dev_hold(rt->dst.dev);
1377                         dev_put(dev);
1378                 }
1379                 spin_unlock_bh(&ul->lock);
1380         }
1381 }
1382 
1383 static bool rt_cache_valid(const struct rtable *rt)
1384 {
1385         return  rt &&
1386                 rt->dst.obsolete == DST_OBSOLETE_FORCE_CHK &&
1387                 !rt_is_expired(rt);
1388 }
1389 
1390 static void rt_set_nexthop(struct rtable *rt, __be32 daddr,
1391                            const struct fib_result *res,
1392                            struct fib_nh_exception *fnhe,
1393                            struct fib_info *fi, u16 type, u32 itag)
1394 {
1395         bool cached = false;
1396 
1397         if (fi) {
1398                 struct fib_nh *nh = &FIB_RES_NH(*res);
1399 
1400                 if (nh->nh_gw && nh->nh_scope == RT_SCOPE_LINK) {
1401                         rt->rt_gateway = nh->nh_gw;
1402                         rt->rt_uses_gateway = 1;
1403                 }
1404                 dst_init_metrics(&rt->dst, fi->fib_metrics, true);
1405 #ifdef CONFIG_IP_ROUTE_CLASSID
1406                 rt->dst.tclassid = nh->nh_tclassid;
1407 #endif
1408                 if (unlikely(fnhe))
1409                         cached = rt_bind_exception(rt, fnhe, daddr);
1410                 else if (!(rt->dst.flags & DST_NOCACHE))
1411                         cached = rt_cache_route(nh, rt);
1412                 if (unlikely(!cached)) {
1413                         /* Routes we intend to cache in nexthop exception or
1414                          * FIB nexthop have the DST_NOCACHE bit clear.
1415                          * However, if we are unsuccessful at storing this
1416                          * route into the cache we really need to set it.
1417                          */
1418                         rt->dst.flags |= DST_NOCACHE;
1419                         if (!rt->rt_gateway)
1420                                 rt->rt_gateway = daddr;
1421                         rt_add_uncached_list(rt);
1422                 }
1423         } else
1424                 rt_add_uncached_list(rt);
1425 
1426 #ifdef CONFIG_IP_ROUTE_CLASSID
1427 #ifdef CONFIG_IP_MULTIPLE_TABLES
1428         set_class_tag(rt, res->tclassid);
1429 #endif
1430         set_class_tag(rt, itag);
1431 #endif
1432 }
1433 
1434 static struct rtable *rt_dst_alloc(struct net_device *dev,
1435                                    bool nopolicy, bool noxfrm, bool will_cache)
1436 {
1437         return dst_alloc(&ipv4_dst_ops, dev, 1, DST_OBSOLETE_FORCE_CHK,
1438                          (will_cache ? 0 : (DST_HOST | DST_NOCACHE)) |
1439                          (nopolicy ? DST_NOPOLICY : 0) |
1440                          (noxfrm ? DST_NOXFRM : 0));
1441 }
1442 
1443 /* called in rcu_read_lock() section */
1444 static int ip_route_input_mc(struct sk_buff *skb, __be32 daddr, __be32 saddr,
1445                                 u8 tos, struct net_device *dev, int our)
1446 {
1447         struct rtable *rth;
1448         struct in_device *in_dev = __in_dev_get_rcu(dev);
1449         u32 itag = 0;
1450         int err;
1451 
1452         /* Primary sanity checks. */
1453 
1454         if (in_dev == NULL)
1455                 return -EINVAL;
1456 
1457         if (ipv4_is_multicast(saddr) || ipv4_is_lbcast(saddr) ||
1458             skb->protocol != htons(ETH_P_IP))
1459                 goto e_inval;
1460 
1461         if (likely(!IN_DEV_ROUTE_LOCALNET(in_dev)))
1462                 if (ipv4_is_loopback(saddr))
1463                         goto e_inval;
1464 
1465         if (ipv4_is_zeronet(saddr)) {
1466                 if (!ipv4_is_local_multicast(daddr))
1467                         goto e_inval;
1468         } else {
1469                 err = fib_validate_source(skb, saddr, 0, tos, 0, dev,
1470                                           in_dev, &itag);
1471                 if (err < 0)
1472                         goto e_err;
1473         }
1474         rth = rt_dst_alloc(dev_net(dev)->loopback_dev,
1475                            IN_DEV_CONF_GET(in_dev, NOPOLICY), false, false);
1476         if (!rth)
1477                 goto e_nobufs;
1478 
1479 #ifdef CONFIG_IP_ROUTE_CLASSID
1480         rth->dst.tclassid = itag;
1481 #endif
1482         rth->dst.output = ip_rt_bug;
1483 
1484         rth->rt_genid   = rt_genid_ipv4(dev_net(dev));
1485         rth->rt_flags   = RTCF_MULTICAST;
1486         rth->rt_type    = RTN_MULTICAST;
1487         rth->rt_is_input= 1;
1488         rth->rt_iif     = 0;
1489         rth->rt_pmtu    = 0;
1490         rth->rt_gateway = 0;
1491         rth->rt_uses_gateway = 0;
1492         INIT_LIST_HEAD(&rth->rt_uncached);
1493         if (our) {
1494                 rth->dst.input= ip_local_deliver;
1495                 rth->rt_flags |= RTCF_LOCAL;
1496         }
1497 
1498 #ifdef CONFIG_IP_MROUTE
1499         if (!ipv4_is_local_multicast(daddr) && IN_DEV_MFORWARD(in_dev))
1500                 rth->dst.input = ip_mr_input;
1501 #endif
1502         RT_CACHE_STAT_INC(in_slow_mc);
1503 
1504         skb_dst_set(skb, &rth->dst);
1505         return 0;
1506 
1507 e_nobufs:
1508         return -ENOBUFS;
1509 e_inval:
1510         return -EINVAL;
1511 e_err:
1512         return err;
1513 }
1514 
1515 
1516 static void ip_handle_martian_source(struct net_device *dev,
1517                                      struct in_device *in_dev,
1518                                      struct sk_buff *skb,
1519                                      __be32 daddr,
1520                                      __be32 saddr)
1521 {
1522         RT_CACHE_STAT_INC(in_martian_src);
1523 #ifdef CONFIG_IP_ROUTE_VERBOSE
1524         if (IN_DEV_LOG_MARTIANS(in_dev) && net_ratelimit()) {
1525                 /*
1526                  *      RFC1812 recommendation, if source is martian,
1527                  *      the only hint is MAC header.
1528                  */
1529                 pr_warn("martian source %pI4 from %pI4, on dev %s\n",
1530                         &daddr, &saddr, dev->name);
1531                 if (dev->hard_header_len && skb_mac_header_was_set(skb)) {
1532                         print_hex_dump(KERN_WARNING, "ll header: ",
1533                                        DUMP_PREFIX_OFFSET, 16, 1,
1534                                        skb_mac_header(skb),
1535                                        dev->hard_header_len, true);
1536                 }
1537         }
1538 #endif
1539 }
1540 
1541 /* called in rcu_read_lock() section */
1542 static int __mkroute_input(struct sk_buff *skb,
1543                            const struct fib_result *res,
1544                            struct in_device *in_dev,
1545                            __be32 daddr, __be32 saddr, u32 tos)
1546 {
1547         struct fib_nh_exception *fnhe;
1548         struct rtable *rth;
1549         int err;
1550         struct in_device *out_dev;
1551         unsigned int flags = 0;
1552         bool do_cache;
1553         u32 itag = 0;
1554 
1555         /* get a working reference to the output device */
1556         out_dev = __in_dev_get_rcu(FIB_RES_DEV(*res));
1557         if (out_dev == NULL) {
1558                 net_crit_ratelimited("Bug in ip_route_input_slow(). Please report.\n");
1559                 return -EINVAL;
1560         }
1561 
1562         err = fib_validate_source(skb, saddr, daddr, tos, FIB_RES_OIF(*res),
1563                                   in_dev->dev, in_dev, &itag);
1564         if (err < 0) {
1565                 ip_handle_martian_source(in_dev->dev, in_dev, skb, daddr,
1566                                          saddr);
1567 
1568                 goto cleanup;
1569         }
1570 
1571         do_cache = res->fi && !itag;
1572         if (out_dev == in_dev && err && IN_DEV_TX_REDIRECTS(out_dev) &&
1573             skb->protocol == htons(ETH_P_IP) &&
1574             (IN_DEV_SHARED_MEDIA(out_dev) ||
1575              inet_addr_onlink(out_dev, saddr, FIB_RES_GW(*res))))
1576                 IPCB(skb)->flags |= IPSKB_DOREDIRECT;
1577 
1578         if (skb->protocol != htons(ETH_P_IP)) {
1579                 /* Not IP (i.e. ARP). Do not create route, if it is
1580                  * invalid for proxy arp. DNAT routes are always valid.
1581                  *
1582                  * Proxy arp feature have been extended to allow, ARP
1583                  * replies back to the same interface, to support
1584                  * Private VLAN switch technologies. See arp.c.
1585                  */
1586                 if (out_dev == in_dev &&
1587                     IN_DEV_PROXY_ARP_PVLAN(in_dev) == 0) {
1588                         err = -EINVAL;
1589                         goto cleanup;
1590                 }
1591         }
1592 
1593         fnhe = find_exception(&FIB_RES_NH(*res), daddr);
1594         if (do_cache) {
1595                 if (fnhe != NULL)
1596                         rth = rcu_dereference(fnhe->fnhe_rth_input);
1597                 else
1598                         rth = rcu_dereference(FIB_RES_NH(*res).nh_rth_input);
1599 
1600                 if (rt_cache_valid(rth)) {
1601                         skb_dst_set_noref(skb, &rth->dst);
1602                         goto out;
1603                 }
1604         }
1605 
1606         rth = rt_dst_alloc(out_dev->dev,
1607                            IN_DEV_CONF_GET(in_dev, NOPOLICY),
1608                            IN_DEV_CONF_GET(out_dev, NOXFRM), do_cache);
1609         if (!rth) {
1610                 err = -ENOBUFS;
1611                 goto cleanup;
1612         }
1613 
1614         rth->rt_genid = rt_genid_ipv4(dev_net(rth->dst.dev));
1615         rth->rt_flags = flags;
1616         rth->rt_type = res->type;
1617         rth->rt_is_input = 1;
1618         rth->rt_iif     = 0;
1619         rth->rt_pmtu    = 0;
1620         rth->rt_gateway = 0;
1621         rth->rt_uses_gateway = 0;
1622         INIT_LIST_HEAD(&rth->rt_uncached);
1623         RT_CACHE_STAT_INC(in_slow_tot);
1624 
1625         rth->dst.input = ip_forward;
1626         rth->dst.output = ip_output;
1627 
1628         rt_set_nexthop(rth, daddr, res, fnhe, res->fi, res->type, itag);
1629         skb_dst_set(skb, &rth->dst);
1630 out:
1631         err = 0;
1632  cleanup:
1633         return err;
1634 }
1635 
1636 static int ip_mkroute_input(struct sk_buff *skb,
1637                             struct fib_result *res,
1638                             const struct flowi4 *fl4,
1639                             struct in_device *in_dev,
1640                             __be32 daddr, __be32 saddr, u32 tos)
1641 {
1642 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1643         if (res->fi && res->fi->fib_nhs > 1)
1644                 fib_select_multipath(res);
1645 #endif
1646 
1647         /* create a routing cache entry */
1648         return __mkroute_input(skb, res, in_dev, daddr, saddr, tos);
1649 }
1650 
1651 /*
1652  *      NOTE. We drop all the packets that has local source
1653  *      addresses, because every properly looped back packet
1654  *      must have correct destination already attached by output routine.
1655  *
1656  *      Such approach solves two big problems:
1657  *      1. Not simplex devices are handled properly.
1658  *      2. IP spoofing attempts are filtered with 100% of guarantee.
1659  *      called with rcu_read_lock()
1660  */
1661 
1662 static int ip_route_input_slow(struct sk_buff *skb, __be32 daddr, __be32 saddr,
1663                                u8 tos, struct net_device *dev)
1664 {
1665         struct fib_result res;
1666         struct in_device *in_dev = __in_dev_get_rcu(dev);
1667         struct flowi4   fl4;
1668         unsigned int    flags = 0;
1669         u32             itag = 0;
1670         struct rtable   *rth;
1671         int             err = -EINVAL;
1672         struct net    *net = dev_net(dev);
1673         bool do_cache;
1674 
1675         /* IP on this device is disabled. */
1676 
1677         if (!in_dev)
1678                 goto out;
1679 
1680         /* Check for the most weird martians, which can be not detected
1681            by fib_lookup.
1682          */
1683 
1684         if (ipv4_is_multicast(saddr) || ipv4_is_lbcast(saddr))
1685                 goto martian_source;
1686 
1687         res.fi = NULL;
1688         if (ipv4_is_lbcast(daddr) || (saddr == 0 && daddr == 0))
1689                 goto brd_input;
1690 
1691         /* Accept zero addresses only to limited broadcast;
1692          * I even do not know to fix it or not. Waiting for complains :-)
1693          */
1694         if (ipv4_is_zeronet(saddr))
1695                 goto martian_source;
1696 
1697         if (ipv4_is_zeronet(daddr))
1698                 goto martian_destination;
1699 
1700         /* Following code try to avoid calling IN_DEV_NET_ROUTE_LOCALNET(),
1701          * and call it once if daddr or/and saddr are loopback addresses
1702          */
1703         if (ipv4_is_loopback(daddr)) {
1704                 if (!IN_DEV_NET_ROUTE_LOCALNET(in_dev, net))
1705                         goto martian_destination;
1706         } else if (ipv4_is_loopback(saddr)) {
1707                 if (!IN_DEV_NET_ROUTE_LOCALNET(in_dev, net))
1708                         goto martian_source;
1709         }
1710 
1711         /*
1712          *      Now we are ready to route packet.
1713          */
1714         fl4.flowi4_oif = 0;
1715         fl4.flowi4_iif = dev->ifindex;
1716         fl4.flowi4_mark = skb->mark;
1717         fl4.flowi4_tos = tos;
1718         fl4.flowi4_scope = RT_SCOPE_UNIVERSE;
1719         fl4.daddr = daddr;
1720         fl4.saddr = saddr;
1721         err = fib_lookup(net, &fl4, &res);
1722         if (err != 0) {
1723                 if (!IN_DEV_FORWARD(in_dev))
1724                         err = -EHOSTUNREACH;
1725                 goto no_route;
1726         }
1727 
1728         if (res.type == RTN_BROADCAST)
1729                 goto brd_input;
1730 
1731         if (res.type == RTN_LOCAL) {
1732                 err = fib_validate_source(skb, saddr, daddr, tos,
1733                                           0, dev, in_dev, &itag);
1734                 if (err < 0)
1735                         goto martian_source_keep_err;
1736                 goto local_input;
1737         }
1738 
1739         if (!IN_DEV_FORWARD(in_dev)) {
1740                 err = -EHOSTUNREACH;
1741                 goto no_route;
1742         }
1743         if (res.type != RTN_UNICAST)
1744                 goto martian_destination;
1745 
1746         err = ip_mkroute_input(skb, &res, &fl4, in_dev, daddr, saddr, tos);
1747 out:    return err;
1748 
1749 brd_input:
1750         if (skb->protocol != htons(ETH_P_IP))
1751                 goto e_inval;
1752 
1753         if (!ipv4_is_zeronet(saddr)) {
1754                 err = fib_validate_source(skb, saddr, 0, tos, 0, dev,
1755                                           in_dev, &itag);
1756                 if (err < 0)
1757                         goto martian_source_keep_err;
1758         }
1759         flags |= RTCF_BROADCAST;
1760         res.type = RTN_BROADCAST;
1761         RT_CACHE_STAT_INC(in_brd);
1762 
1763 local_input:
1764         do_cache = false;
1765         if (res.fi) {
1766                 if (!itag) {
1767                         rth = rcu_dereference(FIB_RES_NH(res).nh_rth_input);
1768                         if (rt_cache_valid(rth)) {
1769                                 skb_dst_set_noref(skb, &rth->dst);
1770                                 err = 0;
1771                                 goto out;
1772                         }
1773                         do_cache = true;
1774                 }
1775         }
1776 
1777         rth = rt_dst_alloc(net->loopback_dev,
1778                            IN_DEV_CONF_GET(in_dev, NOPOLICY), false, do_cache);
1779         if (!rth)
1780                 goto e_nobufs;
1781 
1782         rth->dst.input= ip_local_deliver;
1783         rth->dst.output= ip_rt_bug;
1784 #ifdef CONFIG_IP_ROUTE_CLASSID
1785         rth->dst.tclassid = itag;
1786 #endif
1787 
1788         rth->rt_genid = rt_genid_ipv4(net);
1789         rth->rt_flags   = flags|RTCF_LOCAL;
1790         rth->rt_type    = res.type;
1791         rth->rt_is_input = 1;
1792         rth->rt_iif     = 0;
1793         rth->rt_pmtu    = 0;
1794         rth->rt_gateway = 0;
1795         rth->rt_uses_gateway = 0;
1796         INIT_LIST_HEAD(&rth->rt_uncached);
1797         RT_CACHE_STAT_INC(in_slow_tot);
1798         if (res.type == RTN_UNREACHABLE) {
1799                 rth->dst.input= ip_error;
1800                 rth->dst.error= -err;
1801                 rth->rt_flags   &= ~RTCF_LOCAL;
1802         }
1803         if (do_cache) {
1804                 if (unlikely(!rt_cache_route(&FIB_RES_NH(res), rth))) {
1805                         rth->dst.flags |= DST_NOCACHE;
1806                         rt_add_uncached_list(rth);
1807                 }
1808         }
1809         skb_dst_set(skb, &rth->dst);
1810         err = 0;
1811         goto out;
1812 
1813 no_route:
1814         RT_CACHE_STAT_INC(in_no_route);
1815         res.type = RTN_UNREACHABLE;
1816         res.fi = NULL;
1817         goto local_input;
1818 
1819         /*
1820          *      Do not cache martian addresses: they should be logged (RFC1812)
1821          */
1822 martian_destination:
1823         RT_CACHE_STAT_INC(in_martian_dst);
1824 #ifdef CONFIG_IP_ROUTE_VERBOSE
1825         if (IN_DEV_LOG_MARTIANS(in_dev))
1826                 net_warn_ratelimited("martian destination %pI4 from %pI4, dev %s\n",
1827                                      &daddr, &saddr, dev->name);
1828 #endif
1829 
1830 e_inval:
1831         err = -EINVAL;
1832         goto out;
1833 
1834 e_nobufs:
1835         err = -ENOBUFS;
1836         goto out;
1837 
1838 martian_source:
1839         err = -EINVAL;
1840 martian_source_keep_err:
1841         ip_handle_martian_source(dev, in_dev, skb, daddr, saddr);
1842         goto out;
1843 }
1844 
1845 int ip_route_input_noref(struct sk_buff *skb, __be32 daddr, __be32 saddr,
1846                          u8 tos, struct net_device *dev)
1847 {
1848         int res;
1849 
1850         rcu_read_lock();
1851 
1852         /* Multicast recognition logic is moved from route cache to here.
1853            The problem was that too many Ethernet cards have broken/missing
1854            hardware multicast filters :-( As result the host on multicasting
1855            network acquires a lot of useless route cache entries, sort of
1856            SDR messages from all the world. Now we try to get rid of them.
1857            Really, provided software IP multicast filter is organized
1858            reasonably (at least, hashed), it does not result in a slowdown
1859            comparing with route cache reject entries.
1860            Note, that multicast routers are not affected, because
1861            route cache entry is created eventually.
1862          */
1863         if (ipv4_is_multicast(daddr)) {
1864                 struct in_device *in_dev = __in_dev_get_rcu(dev);
1865 
1866                 if (in_dev) {
1867                         int our = ip_check_mc_rcu(in_dev, daddr, saddr,
1868                                                   ip_hdr(skb)->protocol);
1869                         if (our
1870 #ifdef CONFIG_IP_MROUTE
1871                                 ||
1872                             (!ipv4_is_local_multicast(daddr) &&
1873                              IN_DEV_MFORWARD(in_dev))
1874 #endif
1875                            ) {
1876                                 int res = ip_route_input_mc(skb, daddr, saddr,
1877                                                             tos, dev, our);
1878                                 rcu_read_unlock();
1879                                 return res;
1880                         }
1881                 }
1882                 rcu_read_unlock();
1883                 return -EINVAL;
1884         }
1885         res = ip_route_input_slow(skb, daddr, saddr, tos, dev);
1886         rcu_read_unlock();
1887         return res;
1888 }
1889 EXPORT_SYMBOL(ip_route_input_noref);
1890 
1891 /* called with rcu_read_lock() */
1892 static struct rtable *__mkroute_output(const struct fib_result *res,
1893                                        const struct flowi4 *fl4, int orig_oif,
1894                                        struct net_device *dev_out,
1895                                        unsigned int flags)
1896 {
1897         struct fib_info *fi = res->fi;
1898         struct fib_nh_exception *fnhe;
1899         struct in_device *in_dev;
1900         u16 type = res->type;
1901         struct rtable *rth;
1902         bool do_cache;
1903 
1904         in_dev = __in_dev_get_rcu(dev_out);
1905         if (!in_dev)
1906                 return ERR_PTR(-EINVAL);
1907 
1908         if (likely(!IN_DEV_ROUTE_LOCALNET(in_dev)))
1909                 if (ipv4_is_loopback(fl4->saddr) && !(dev_out->flags & IFF_LOOPBACK))
1910                         return ERR_PTR(-EINVAL);
1911 
1912         if (ipv4_is_lbcast(fl4->daddr))
1913                 type = RTN_BROADCAST;
1914         else if (ipv4_is_multicast(fl4->daddr))
1915                 type = RTN_MULTICAST;
1916         else if (ipv4_is_zeronet(fl4->daddr))
1917                 return ERR_PTR(-EINVAL);
1918 
1919         if (dev_out->flags & IFF_LOOPBACK)
1920                 flags |= RTCF_LOCAL;
1921 
1922         do_cache = true;
1923         if (type == RTN_BROADCAST) {
1924                 flags |= RTCF_BROADCAST | RTCF_LOCAL;
1925                 fi = NULL;
1926         } else if (type == RTN_MULTICAST) {
1927                 flags |= RTCF_MULTICAST | RTCF_LOCAL;
1928                 if (!ip_check_mc_rcu(in_dev, fl4->daddr, fl4->saddr,
1929                                      fl4->flowi4_proto))
1930                         flags &= ~RTCF_LOCAL;
1931                 else
1932                         do_cache = false;
1933                 /* If multicast route do not exist use
1934                  * default one, but do not gateway in this case.
1935                  * Yes, it is hack.
1936                  */
1937                 if (fi && res->prefixlen < 4)
1938                         fi = NULL;
1939         }
1940 
1941         fnhe = NULL;
1942         do_cache &= fi != NULL;
1943         if (do_cache) {
1944                 struct rtable __rcu **prth;
1945                 struct fib_nh *nh = &FIB_RES_NH(*res);
1946 
1947                 fnhe = find_exception(nh, fl4->daddr);
1948                 if (fnhe)
1949                         prth = &fnhe->fnhe_rth_output;
1950                 else {
1951                         if (unlikely(fl4->flowi4_flags &
1952                                      FLOWI_FLAG_KNOWN_NH &&
1953                                      !(nh->nh_gw &&
1954                                        nh->nh_scope == RT_SCOPE_LINK))) {
1955                                 do_cache = false;
1956                                 goto add;
1957                         }
1958                         prth = raw_cpu_ptr(nh->nh_pcpu_rth_output);
1959                 }
1960                 rth = rcu_dereference(*prth);
1961                 if (rt_cache_valid(rth)) {
1962                         dst_hold(&rth->dst);
1963                         return rth;
1964                 }
1965         }
1966 
1967 add:
1968         rth = rt_dst_alloc(dev_out,
1969                            IN_DEV_CONF_GET(in_dev, NOPOLICY),
1970                            IN_DEV_CONF_GET(in_dev, NOXFRM),
1971                            do_cache);
1972         if (!rth)
1973                 return ERR_PTR(-ENOBUFS);
1974 
1975         rth->dst.output = ip_output;
1976 
1977         rth->rt_genid = rt_genid_ipv4(dev_net(dev_out));
1978         rth->rt_flags   = flags;
1979         rth->rt_type    = type;
1980         rth->rt_is_input = 0;
1981         rth->rt_iif     = orig_oif ? : 0;
1982         rth->rt_pmtu    = 0;
1983         rth->rt_gateway = 0;
1984         rth->rt_uses_gateway = 0;
1985         INIT_LIST_HEAD(&rth->rt_uncached);
1986 
1987         RT_CACHE_STAT_INC(out_slow_tot);
1988 
1989         if (flags & RTCF_LOCAL)
1990                 rth->dst.input = ip_local_deliver;
1991         if (flags & (RTCF_BROADCAST | RTCF_MULTICAST)) {
1992                 if (flags & RTCF_LOCAL &&
1993                     !(dev_out->flags & IFF_LOOPBACK)) {
1994                         rth->dst.output = ip_mc_output;
1995                         RT_CACHE_STAT_INC(out_slow_mc);
1996                 }
1997 #ifdef CONFIG_IP_MROUTE
1998                 if (type == RTN_MULTICAST) {
1999                         if (IN_DEV_MFORWARD(in_dev) &&
2000                             !ipv4_is_local_multicast(fl4->daddr)) {
2001                                 rth->dst.input = ip_mr_input;
2002                                 rth->dst.output = ip_mc_output;
2003                         }
2004                 }
2005 #endif
2006         }
2007 
2008         rt_set_nexthop(rth, fl4->daddr, res, fnhe, fi, type, 0);
2009 
2010         return rth;
2011 }
2012 
2013 /*
2014  * Major route resolver routine.
2015  */
2016 
2017 struct rtable *__ip_route_output_key(struct net *net, struct flowi4 *fl4)
2018 {
2019         struct net_device *dev_out = NULL;
2020         __u8 tos = RT_FL_TOS(fl4);
2021         unsigned int flags = 0;
2022         struct fib_result res;
2023         struct rtable *rth;
2024         int orig_oif;
2025 
2026         res.tclassid    = 0;
2027         res.fi          = NULL;
2028         res.table       = NULL;
2029 
2030         orig_oif = fl4->flowi4_oif;
2031 
2032         fl4->flowi4_iif = LOOPBACK_IFINDEX;
2033         fl4->flowi4_tos = tos & IPTOS_RT_MASK;
2034         fl4->flowi4_scope = ((tos & RTO_ONLINK) ?
2035                          RT_SCOPE_LINK : RT_SCOPE_UNIVERSE);
2036 
2037         rcu_read_lock();
2038         if (fl4->saddr) {
2039                 rth = ERR_PTR(-EINVAL);
2040                 if (ipv4_is_multicast(fl4->saddr) ||
2041                     ipv4_is_lbcast(fl4->saddr) ||
2042                     ipv4_is_zeronet(fl4->saddr))
2043                         goto out;
2044 
2045                 /* I removed check for oif == dev_out->oif here.
2046                    It was wrong for two reasons:
2047                    1. ip_dev_find(net, saddr) can return wrong iface, if saddr
2048                       is assigned to multiple interfaces.
2049                    2. Moreover, we are allowed to send packets with saddr
2050                       of another iface. --ANK
2051                  */
2052 
2053                 if (fl4->flowi4_oif == 0 &&
2054                     (ipv4_is_multicast(fl4->daddr) ||
2055                      ipv4_is_lbcast(fl4->daddr))) {
2056                         /* It is equivalent to inet_addr_type(saddr) == RTN_LOCAL */
2057                         dev_out = __ip_dev_find(net, fl4->saddr, false);
2058                         if (dev_out == NULL)
2059                                 goto out;
2060 
2061                         /* Special hack: user can direct multicasts
2062                            and limited broadcast via necessary interface
2063                            without fiddling with IP_MULTICAST_IF or IP_PKTINFO.
2064                            This hack is not just for fun, it allows
2065                            vic,vat and friends to work.
2066                            They bind socket to loopback, set ttl to zero
2067                            and expect that it will work.
2068                            From the viewpoint of routing cache they are broken,
2069                            because we are not allowed to build multicast path
2070                            with loopback source addr (look, routing cache
2071                            cannot know, that ttl is zero, so that packet
2072                            will not leave this host and route is valid).
2073                            Luckily, this hack is good workaround.
2074                          */
2075 
2076                         fl4->flowi4_oif = dev_out->ifindex;
2077                         goto make_route;
2078                 }
2079 
2080                 if (!(fl4->flowi4_flags & FLOWI_FLAG_ANYSRC)) {
2081                         /* It is equivalent to inet_addr_type(saddr) == RTN_LOCAL */
2082                         if (!__ip_dev_find(net, fl4->saddr, false))
2083                                 goto out;
2084                 }
2085         }
2086 
2087 
2088         if (fl4->flowi4_oif) {
2089                 dev_out = dev_get_by_index_rcu(net, fl4->flowi4_oif);
2090                 rth = ERR_PTR(-ENODEV);
2091                 if (dev_out == NULL)
2092                         goto out;
2093 
2094                 /* RACE: Check return value of inet_select_addr instead. */
2095                 if (!(dev_out->flags & IFF_UP) || !__in_dev_get_rcu(dev_out)) {
2096                         rth = ERR_PTR(-ENETUNREACH);
2097                         goto out;
2098                 }
2099                 if (ipv4_is_local_multicast(fl4->daddr) ||
2100                     ipv4_is_lbcast(fl4->daddr)) {
2101                         if (!fl4->saddr)
2102                                 fl4->saddr = inet_select_addr(dev_out, 0,
2103                                                               RT_SCOPE_LINK);
2104                         goto make_route;
2105                 }
2106                 if (!fl4->saddr) {
2107                         if (ipv4_is_multicast(fl4->daddr))
2108                                 fl4->saddr = inet_select_addr(dev_out, 0,
2109                                                               fl4->flowi4_scope);
2110                         else if (!fl4->daddr)
2111                                 fl4->saddr = inet_select_addr(dev_out, 0,
2112                                                               RT_SCOPE_HOST);
2113                 }
2114         }
2115 
2116         if (!fl4->daddr) {
2117                 fl4->daddr = fl4->saddr;
2118                 if (!fl4->daddr)
2119                         fl4->daddr = fl4->saddr = htonl(INADDR_LOOPBACK);
2120                 dev_out = net->loopback_dev;
2121                 fl4->flowi4_oif = LOOPBACK_IFINDEX;
2122                 res.type = RTN_LOCAL;
2123                 flags |= RTCF_LOCAL;
2124                 goto make_route;
2125         }
2126 
2127         if (fib_lookup(net, fl4, &res)) {
2128                 res.fi = NULL;
2129                 res.table = NULL;
2130                 if (fl4->flowi4_oif) {
2131                         /* Apparently, routing tables are wrong. Assume,
2132                            that the destination is on link.
2133 
2134                            WHY? DW.
2135                            Because we are allowed to send to iface
2136                            even if it has NO routes and NO assigned
2137                            addresses. When oif is specified, routing
2138                            tables are looked up with only one purpose:
2139                            to catch if destination is gatewayed, rather than
2140                            direct. Moreover, if MSG_DONTROUTE is set,
2141                            we send packet, ignoring both routing tables
2142                            and ifaddr state. --ANK
2143 
2144 
2145                            We could make it even if oif is unknown,
2146                            likely IPv6, but we do not.
2147                          */
2148 
2149                         if (fl4->saddr == 0)
2150                                 fl4->saddr = inet_select_addr(dev_out, 0,
2151                                                               RT_SCOPE_LINK);
2152                         res.type = RTN_UNICAST;
2153                         goto make_route;
2154                 }
2155                 rth = ERR_PTR(-ENETUNREACH);
2156                 goto out;
2157         }
2158 
2159         if (res.type == RTN_LOCAL) {
2160                 if (!fl4->saddr) {
2161                         if (res.fi->fib_prefsrc)
2162                                 fl4->saddr = res.fi->fib_prefsrc;
2163                         else
2164                                 fl4->saddr = fl4->daddr;
2165                 }
2166                 dev_out = net->loopback_dev;
2167                 fl4->flowi4_oif = dev_out->ifindex;
2168                 flags |= RTCF_LOCAL;
2169                 goto make_route;
2170         }
2171 
2172 #ifdef CONFIG_IP_ROUTE_MULTIPATH
2173         if (res.fi->fib_nhs > 1 && fl4->flowi4_oif == 0)
2174                 fib_select_multipath(&res);
2175         else
2176 #endif
2177         if (!res.prefixlen &&
2178             res.table->tb_num_default > 1 &&
2179             res.type == RTN_UNICAST && !fl4->flowi4_oif)
2180                 fib_select_default(&res);
2181 
2182         if (!fl4->saddr)
2183                 fl4->saddr = FIB_RES_PREFSRC(net, res);
2184 
2185         dev_out = FIB_RES_DEV(res);
2186         fl4->flowi4_oif = dev_out->ifindex;
2187 
2188 
2189 make_route:
2190         rth = __mkroute_output(&res, fl4, orig_oif, dev_out, flags);
2191 
2192 out:
2193         rcu_read_unlock();
2194         return rth;
2195 }
2196 EXPORT_SYMBOL_GPL(__ip_route_output_key);
2197 
2198 static struct dst_entry *ipv4_blackhole_dst_check(struct dst_entry *dst, u32 cookie)
2199 {
2200         return NULL;
2201 }
2202 
2203 static unsigned int ipv4_blackhole_mtu(const struct dst_entry *dst)
2204 {
2205         unsigned int mtu = dst_metric_raw(dst, RTAX_MTU);
2206 
2207         return mtu ? : dst->dev->mtu;
2208 }
2209 
2210 static void ipv4_rt_blackhole_update_pmtu(struct dst_entry *dst, struct sock *sk,
2211                                           struct sk_buff *skb, u32 mtu)
2212 {
2213 }
2214 
2215 static void ipv4_rt_blackhole_redirect(struct dst_entry *dst, struct sock *sk,
2216                                        struct sk_buff *skb)
2217 {
2218 }
2219 
2220 static u32 *ipv4_rt_blackhole_cow_metrics(struct dst_entry *dst,
2221                                           unsigned long old)
2222 {
2223         return NULL;
2224 }
2225 
2226 static struct dst_ops ipv4_dst_blackhole_ops = {
2227         .family                 =       AF_INET,
2228         .protocol               =       cpu_to_be16(ETH_P_IP),
2229         .check                  =       ipv4_blackhole_dst_check,
2230         .mtu                    =       ipv4_blackhole_mtu,
2231         .default_advmss         =       ipv4_default_advmss,
2232         .update_pmtu            =       ipv4_rt_blackhole_update_pmtu,
2233         .redirect               =       ipv4_rt_blackhole_redirect,
2234         .cow_metrics            =       ipv4_rt_blackhole_cow_metrics,
2235         .neigh_lookup           =       ipv4_neigh_lookup,
2236 };
2237 
2238 struct dst_entry *ipv4_blackhole_route(struct net *net, struct dst_entry *dst_orig)
2239 {
2240         struct rtable *ort = (struct rtable *) dst_orig;
2241         struct rtable *rt;
2242 
2243         rt = dst_alloc(&ipv4_dst_blackhole_ops, NULL, 1, DST_OBSOLETE_NONE, 0);
2244         if (rt) {
2245                 struct dst_entry *new = &rt->dst;
2246 
2247                 new->__use = 1;
2248                 new->input = dst_discard;
2249                 new->output = dst_discard_sk;
2250 
2251                 new->dev = ort->dst.dev;
2252                 if (new->dev)
2253                         dev_hold(new->dev);
2254 
2255                 rt->rt_is_input = ort->rt_is_input;
2256                 rt->rt_iif = ort->rt_iif;
2257                 rt->rt_pmtu = ort->rt_pmtu;
2258 
2259                 rt->rt_genid = rt_genid_ipv4(net);
2260                 rt->rt_flags = ort->rt_flags;
2261                 rt->rt_type = ort->rt_type;
2262                 rt->rt_gateway = ort->rt_gateway;
2263                 rt->rt_uses_gateway = ort->rt_uses_gateway;
2264 
2265                 INIT_LIST_HEAD(&rt->rt_uncached);
2266 
2267                 dst_free(new);
2268         }
2269 
2270         dst_release(dst_orig);
2271 
2272         return rt ? &rt->dst : ERR_PTR(-ENOMEM);
2273 }
2274 
2275 struct rtable *ip_route_output_flow(struct net *net, struct flowi4 *flp4,
2276                                     struct sock *sk)
2277 {
2278         struct rtable *rt = __ip_route_output_key(net, flp4);
2279 
2280         if (IS_ERR(rt))
2281                 return rt;
2282 
2283         if (flp4->flowi4_proto)
2284                 rt = (struct rtable *)xfrm_lookup_route(net, &rt->dst,
2285                                                         flowi4_to_flowi(flp4),
2286                                                         sk, 0);
2287 
2288         return rt;
2289 }
2290 EXPORT_SYMBOL_GPL(ip_route_output_flow);
2291 
2292 static int rt_fill_info(struct net *net,  __be32 dst, __be32 src,
2293                         struct flowi4 *fl4, struct sk_buff *skb, u32 portid,
2294                         u32 seq, int event, int nowait, unsigned int flags)
2295 {
2296         struct rtable *rt = skb_rtable(skb);
2297         struct rtmsg *r;
2298         struct nlmsghdr *nlh;
2299         unsigned long expires = 0;
2300         u32 error;
2301         u32 metrics[RTAX_MAX];
2302 
2303         nlh = nlmsg_put(skb, portid, seq, event, sizeof(*r), flags);
2304         if (nlh == NULL)
2305                 return -EMSGSIZE;
2306 
2307         r = nlmsg_data(nlh);
2308         r->rtm_family    = AF_INET;
2309         r->rtm_dst_len  = 32;
2310         r->rtm_src_len  = 0;
2311         r->rtm_tos      = fl4->flowi4_tos;
2312         r->rtm_table    = RT_TABLE_MAIN;
2313         if (nla_put_u32(skb, RTA_TABLE, RT_TABLE_MAIN))
2314                 goto nla_put_failure;
2315         r->rtm_type     = rt->rt_type;
2316         r->rtm_scope    = RT_SCOPE_UNIVERSE;
2317         r->rtm_protocol = RTPROT_UNSPEC;
2318         r->rtm_flags    = (rt->rt_flags & ~0xFFFF) | RTM_F_CLONED;
2319         if (rt->rt_flags & RTCF_NOTIFY)
2320                 r->rtm_flags |= RTM_F_NOTIFY;
2321         if (IPCB(skb)->flags & IPSKB_DOREDIRECT)
2322                 r->rtm_flags |= RTCF_DOREDIRECT;
2323 
2324         if (nla_put_be32(skb, RTA_DST, dst))
2325                 goto nla_put_failure;
2326         if (src) {
2327                 r->rtm_src_len = 32;
2328                 if (nla_put_be32(skb, RTA_SRC, src))
2329                         goto nla_put_failure;
2330         }
2331         if (rt->dst.dev &&
2332             nla_put_u32(skb, RTA_OIF, rt->dst.dev->ifindex))
2333                 goto nla_put_failure;
2334 #ifdef CONFIG_IP_ROUTE_CLASSID
2335         if (rt->dst.tclassid &&
2336             nla_put_u32(skb, RTA_FLOW, rt->dst.tclassid))
2337                 goto nla_put_failure;
2338 #endif
2339         if (!rt_is_input_route(rt) &&
2340             fl4->saddr != src) {
2341                 if (nla_put_be32(skb, RTA_PREFSRC, fl4->saddr))
2342                         goto nla_put_failure;
2343         }
2344         if (rt->rt_uses_gateway &&
2345             nla_put_be32(skb, RTA_GATEWAY, rt->rt_gateway))
2346                 goto nla_put_failure;
2347 
2348         expires = rt->dst.expires;
2349         if (expires) {
2350                 unsigned long now = jiffies;
2351 
2352                 if (time_before(now, expires))
2353                         expires -= now;
2354                 else
2355                         expires = 0;
2356         }
2357 
2358         memcpy(metrics, dst_metrics_ptr(&rt->dst), sizeof(metrics));
2359         if (rt->rt_pmtu && expires)
2360                 metrics[RTAX_MTU - 1] = rt->rt_pmtu;
2361         if (rtnetlink_put_metrics(skb, metrics) < 0)
2362                 goto nla_put_failure;
2363 
2364         if (fl4->flowi4_mark &&
2365             nla_put_u32(skb, RTA_MARK, fl4->flowi4_mark))
2366                 goto nla_put_failure;
2367 
2368         error = rt->dst.error;
2369 
2370         if (rt_is_input_route(rt)) {
2371 #ifdef CONFIG_IP_MROUTE
2372                 if (ipv4_is_multicast(dst) && !ipv4_is_local_multicast(dst) &&
2373                     IPV4_DEVCONF_ALL(net, MC_FORWARDING)) {
2374                         int err = ipmr_get_route(net, skb,
2375                                                  fl4->saddr, fl4->daddr,
2376                                                  r, nowait);
2377                         if (err <= 0) {
2378                                 if (!nowait) {
2379                                         if (err == 0)
2380                                                 return 0;
2381                                         goto nla_put_failure;
2382                                 } else {
2383                                         if (err == -EMSGSIZE)
2384                                                 goto nla_put_failure;
2385                                         error = err;
2386                                 }
2387                         }
2388                 } else
2389 #endif
2390                         if (nla_put_u32(skb, RTA_IIF, skb->dev->ifindex))
2391                                 goto nla_put_failure;
2392         }
2393 
2394         if (rtnl_put_cacheinfo(skb, &rt->dst, 0, expires, error) < 0)
2395                 goto nla_put_failure;
2396 
2397         nlmsg_end(skb, nlh);
2398         return 0;
2399 
2400 nla_put_failure:
2401         nlmsg_cancel(skb, nlh);
2402         return -EMSGSIZE;
2403 }
2404 
2405 static int inet_rtm_getroute(struct sk_buff *in_skb, struct nlmsghdr *nlh)
2406 {
2407         struct net *net = sock_net(in_skb->sk);
2408         struct rtmsg *rtm;
2409         struct nlattr *tb[RTA_MAX+1];
2410         struct rtable *rt = NULL;
2411         struct flowi4 fl4;
2412         __be32 dst = 0;
2413         __be32 src = 0;
2414         u32 iif;
2415         int err;
2416         int mark;
2417         struct sk_buff *skb;
2418 
2419         err = nlmsg_parse(nlh, sizeof(*rtm), tb, RTA_MAX, rtm_ipv4_policy);
2420         if (err < 0)
2421                 goto errout;
2422 
2423         rtm = nlmsg_data(nlh);
2424 
2425         skb = alloc_skb(NLMSG_GOODSIZE, GFP_KERNEL);
2426         if (skb == NULL) {
2427                 err = -ENOBUFS;
2428                 goto errout;
2429         }
2430 
2431         /* Reserve room for dummy headers, this skb can pass
2432            through good chunk of routing engine.
2433          */
2434         skb_reset_mac_header(skb);
2435         skb_reset_network_header(skb);
2436 
2437         /* Bugfix: need to give ip_route_input enough of an IP header to not gag. */
2438         ip_hdr(skb)->protocol = IPPROTO_ICMP;
2439         skb_reserve(skb, MAX_HEADER + sizeof(struct iphdr));
2440 
2441         src = tb[RTA_SRC] ? nla_get_be32(tb[RTA_SRC]) : 0;
2442         dst = tb[RTA_DST] ? nla_get_be32(tb[RTA_DST]) : 0;
2443         iif = tb[RTA_IIF] ? nla_get_u32(tb[RTA_IIF]) : 0;
2444         mark = tb[RTA_MARK] ? nla_get_u32(tb[RTA_MARK]) : 0;
2445 
2446         memset(&fl4, 0, sizeof(fl4));
2447         fl4.daddr = dst;
2448         fl4.saddr = src;
2449         fl4.flowi4_tos = rtm->rtm_tos;
2450         fl4.flowi4_oif = tb[RTA_OIF] ? nla_get_u32(tb[RTA_OIF]) : 0;
2451         fl4.flowi4_mark = mark;
2452 
2453         if (iif) {
2454                 struct net_device *dev;
2455 
2456                 dev = __dev_get_by_index(net, iif);
2457                 if (dev == NULL) {
2458                         err = -ENODEV;
2459                         goto errout_free;
2460                 }
2461 
2462                 skb->protocol   = htons(ETH_P_IP);
2463                 skb->dev        = dev;
2464                 skb->mark       = mark;
2465                 local_bh_disable();
2466                 err = ip_route_input(skb, dst, src, rtm->rtm_tos, dev);
2467                 local_bh_enable();
2468 
2469                 rt = skb_rtable(skb);
2470                 if (err == 0 && rt->dst.error)
2471                         err = -rt->dst.error;
2472         } else {
2473                 rt = ip_route_output_key(net, &fl4);
2474 
2475                 err = 0;
2476                 if (IS_ERR(rt))
2477                         err = PTR_ERR(rt);
2478         }
2479 
2480         if (err)
2481                 goto errout_free;
2482 
2483         skb_dst_set(skb, &rt->dst);
2484         if (rtm->rtm_flags & RTM_F_NOTIFY)
2485                 rt->rt_flags |= RTCF_NOTIFY;
2486 
2487         err = rt_fill_info(net, dst, src, &fl4, skb,
2488                            NETLINK_CB(in_skb).portid, nlh->nlmsg_seq,
2489                            RTM_NEWROUTE, 0, 0);
2490         if (err < 0)
2491                 goto errout_free;
2492 
2493         err = rtnl_unicast(skb, net, NETLINK_CB(in_skb).portid);
2494 errout:
2495         return err;
2496 
2497 errout_free:
2498         kfree_skb(skb);
2499         goto errout;
2500 }
2501 
2502 void ip_rt_multicast_event(struct in_device *in_dev)
2503 {
2504         rt_cache_flush(dev_net(in_dev->dev));
2505 }
2506 
2507 #ifdef CONFIG_SYSCTL
2508 static int ip_rt_gc_timeout __read_mostly       = RT_GC_TIMEOUT;
2509 static int ip_rt_gc_interval __read_mostly  = 60 * HZ;
2510 static int ip_rt_gc_min_interval __read_mostly  = HZ / 2;
2511 static int ip_rt_gc_elasticity __read_mostly    = 8;
2512 
2513 static int ipv4_sysctl_rtcache_flush(struct ctl_table *__ctl, int write,
2514                                         void __user *buffer,
2515                                         size_t *lenp, loff_t *ppos)
2516 {
2517         struct net *net = (struct net *)__ctl->extra1;
2518 
2519         if (write) {
2520                 rt_cache_flush(net);
2521                 fnhe_genid_bump(net);
2522                 return 0;
2523         }
2524 
2525         return -EINVAL;
2526 }
2527 
2528 static struct ctl_table ipv4_route_table[] = {
2529         {
2530                 .procname       = "gc_thresh",
2531                 .data           = &ipv4_dst_ops.gc_thresh,
2532                 .maxlen         = sizeof(int),
2533                 .mode           = 0644,
2534                 .proc_handler   = proc_dointvec,
2535         },
2536         {
2537                 .procname       = "max_size",
2538                 .data           = &ip_rt_max_size,
2539                 .maxlen         = sizeof(int),
2540                 .mode           = 0644,
2541                 .proc_handler   = proc_dointvec,
2542         },
2543         {
2544                 /*  Deprecated. Use gc_min_interval_ms */
2545 
2546                 .procname       = "gc_min_interval",
2547                 .data           = &ip_rt_gc_min_interval,
2548                 .maxlen         = sizeof(int),
2549                 .mode           = 0644,
2550                 .proc_handler   = proc_dointvec_jiffies,
2551         },
2552         {
2553                 .procname       = "gc_min_interval_ms",
2554                 .data           = &ip_rt_gc_min_interval,
2555                 .maxlen         = sizeof(int),
2556                 .mode           = 0644,
2557                 .proc_handler   = proc_dointvec_ms_jiffies,
2558         },
2559         {
2560                 .procname       = "gc_timeout",
2561                 .data           = &ip_rt_gc_timeout,
2562                 .maxlen         = sizeof(int),
2563                 .mode           = 0644,
2564                 .proc_handler   = proc_dointvec_jiffies,
2565         },
2566         {
2567                 .procname       = "gc_interval",
2568                 .data           = &ip_rt_gc_interval,
2569                 .maxlen         = sizeof(int),
2570                 .mode           = 0644,
2571                 .proc_handler   = proc_dointvec_jiffies,
2572         },
2573         {
2574                 .procname       = "redirect_load",
2575                 .data           = &ip_rt_redirect_load,
2576                 .maxlen         = sizeof(int),
2577                 .mode           = 0644,
2578                 .proc_handler   = proc_dointvec,
2579         },
2580         {
2581                 .procname       = "redirect_number",
2582                 .data           = &ip_rt_redirect_number,
2583                 .maxlen         = sizeof(int),
2584                 .mode           = 0644,
2585                 .proc_handler   = proc_dointvec,
2586         },
2587         {
2588                 .procname       = "redirect_silence",
2589                 .data           = &ip_rt_redirect_silence,
2590                 .maxlen         = sizeof(int),
2591                 .mode           = 0644,
2592                 .proc_handler   = proc_dointvec,
2593         },
2594         {
2595                 .procname       = "error_cost",
2596                 .data           = &ip_rt_error_cost,
2597                 .maxlen         = sizeof(int),
2598                 .mode           = 0644,
2599                 .proc_handler   = proc_dointvec,
2600         },
2601         {
2602                 .procname       = "error_burst",
2603                 .data           = &ip_rt_error_burst,
2604                 .maxlen         = sizeof(int),
2605                 .mode           = 0644,
2606                 .proc_handler   = proc_dointvec,
2607         },
2608         {
2609                 .procname       = "gc_elasticity",
2610                 .data           = &ip_rt_gc_elasticity,
2611                 .maxlen         = sizeof(int),
2612                 .mode           = 0644,
2613                 .proc_handler   = proc_dointvec,
2614         },
2615         {
2616                 .procname       = "mtu_expires",
2617                 .data           = &ip_rt_mtu_expires,
2618                 .maxlen         = sizeof(int),
2619                 .mode           = 0644,
2620                 .proc_handler   = proc_dointvec_jiffies,
2621         },
2622         {
2623                 .procname       = "min_pmtu",
2624                 .data           = &ip_rt_min_pmtu,
2625                 .maxlen         = sizeof(int),
2626                 .mode           = 0644,
2627                 .proc_handler   = proc_dointvec,
2628         },
2629         {
2630                 .procname       = "min_adv_mss",
2631                 .data           = &ip_rt_min_advmss,
2632                 .maxlen         = sizeof(int),
2633                 .mode           = 0644,
2634                 .proc_handler   = proc_dointvec,
2635         },
2636         { }
2637 };
2638 
2639 static struct ctl_table ipv4_route_flush_table[] = {
2640         {
2641                 .procname       = "flush",
2642                 .maxlen         = sizeof(int),
2643                 .mode           = 0200,
2644                 .proc_handler   = ipv4_sysctl_rtcache_flush,
2645         },
2646         { },
2647 };
2648 
2649 static __net_init int sysctl_route_net_init(struct net *net)
2650 {
2651         struct ctl_table *tbl;
2652 
2653         tbl = ipv4_route_flush_table;
2654         if (!net_eq(net, &init_net)) {
2655                 tbl = kmemdup(tbl, sizeof(ipv4_route_flush_table), GFP_KERNEL);
2656                 if (tbl == NULL)
2657                         goto err_dup;
2658 
2659                 /* Don't export sysctls to unprivileged users */
2660                 if (net->user_ns != &init_user_ns)
2661                         tbl[0].procname = NULL;
2662         }
2663         tbl[0].extra1 = net;
2664 
2665         net->ipv4.route_hdr = register_net_sysctl(net, "net/ipv4/route", tbl);
2666         if (net->ipv4.route_hdr == NULL)
2667                 goto err_reg;
2668         return 0;
2669 
2670 err_reg:
2671         if (tbl != ipv4_route_flush_table)
2672                 kfree(tbl);
2673 err_dup:
2674         return -ENOMEM;
2675 }
2676 
2677 static __net_exit void sysctl_route_net_exit(struct net *net)
2678 {
2679         struct ctl_table *tbl;
2680 
2681         tbl = net->ipv4.route_hdr->ctl_table_arg;
2682         unregister_net_sysctl_table(net->ipv4.route_hdr);
2683         BUG_ON(tbl == ipv4_route_flush_table);
2684         kfree(tbl);
2685 }
2686 
2687 static __net_initdata struct pernet_operations sysctl_route_ops = {
2688         .init = sysctl_route_net_init,
2689         .exit = sysctl_route_net_exit,
2690 };
2691 #endif
2692 
2693 static __net_init int rt_genid_init(struct net *net)
2694 {
2695         atomic_set(&net->ipv4.rt_genid, 0);
2696         atomic_set(&net->fnhe_genid, 0);
2697         get_random_bytes(&net->ipv4.dev_addr_genid,
2698                          sizeof(net->ipv4.dev_addr_genid));
2699         return 0;
2700 }
2701 
2702 static __net_initdata struct pernet_operations rt_genid_ops = {
2703         .init = rt_genid_init,
2704 };
2705 
2706 static int __net_init ipv4_inetpeer_init(struct net *net)
2707 {
2708         struct inet_peer_base *bp = kmalloc(sizeof(*bp), GFP_KERNEL);
2709 
2710         if (!bp)
2711                 return -ENOMEM;
2712         inet_peer_base_init(bp);
2713         net->ipv4.peers = bp;
2714         return 0;
2715 }
2716 
2717 static void __net_exit ipv4_inetpeer_exit(struct net *net)
2718 {
2719         struct inet_peer_base *bp = net->ipv4.peers;
2720 
2721         net->ipv4.peers = NULL;
2722         inetpeer_invalidate_tree(bp);
2723         kfree(bp);
2724 }
2725 
2726 static __net_initdata struct pernet_operations ipv4_inetpeer_ops = {
2727         .init   =       ipv4_inetpeer_init,
2728         .exit   =       ipv4_inetpeer_exit,
2729 };
2730 
2731 #ifdef CONFIG_IP_ROUTE_CLASSID
2732 struct ip_rt_acct __percpu *ip_rt_acct __read_mostly;
2733 #endif /* CONFIG_IP_ROUTE_CLASSID */
2734 
2735 int __init ip_rt_init(void)
2736 {
2737         int rc = 0;
2738         int cpu;
2739 
2740         ip_idents = kmalloc(IP_IDENTS_SZ * sizeof(*ip_idents), GFP_KERNEL);
2741         if (!ip_idents)
2742                 panic("IP: failed to allocate ip_idents\n");
2743 
2744         prandom_bytes(ip_idents, IP_IDENTS_SZ * sizeof(*ip_idents));
2745 
2746         for_each_possible_cpu(cpu) {
2747                 struct uncached_list *ul = &per_cpu(rt_uncached_list, cpu);
2748 
2749                 INIT_LIST_HEAD(&ul->head);
2750                 spin_lock_init(&ul->lock);
2751         }
2752 #ifdef CONFIG_IP_ROUTE_CLASSID
2753         ip_rt_acct = __alloc_percpu(256 * sizeof(struct ip_rt_acct), __alignof__(struct ip_rt_acct));
2754         if (!ip_rt_acct)
2755                 panic("IP: failed to allocate ip_rt_acct\n");
2756 #endif
2757 
2758         ipv4_dst_ops.kmem_cachep =
2759                 kmem_cache_create("ip_dst_cache", sizeof(struct rtable), 0,
2760                                   SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
2761 
2762         ipv4_dst_blackhole_ops.kmem_cachep = ipv4_dst_ops.kmem_cachep;
2763 
2764         if (dst_entries_init(&ipv4_dst_ops) < 0)
2765                 panic("IP: failed to allocate ipv4_dst_ops counter\n");
2766 
2767         if (dst_entries_init(&ipv4_dst_blackhole_ops) < 0)
2768                 panic("IP: failed to allocate ipv4_dst_blackhole_ops counter\n");
2769 
2770         ipv4_dst_ops.gc_thresh = ~0;
2771         ip_rt_max_size = INT_MAX;
2772 
2773         devinet_init();
2774         ip_fib_init();
2775 
2776         if (ip_rt_proc_init())
2777                 pr_err("Unable to create route proc files\n");
2778 #ifdef CONFIG_XFRM
2779         xfrm_init();
2780         xfrm4_init();
2781 #endif
2782         rtnl_register(PF_INET, RTM_GETROUTE, inet_rtm_getroute, NULL, NULL);
2783 
2784 #ifdef CONFIG_SYSCTL
2785         register_pernet_subsys(&sysctl_route_ops);
2786 #endif
2787         register_pernet_subsys(&rt_genid_ops);
2788         register_pernet_subsys(&ipv4_inetpeer_ops);
2789         return rc;
2790 }
2791 
2792 #ifdef CONFIG_SYSCTL
2793 /*
2794  * We really need to sanitize the damn ipv4 init order, then all
2795  * this nonsense will go away.
2796  */
2797 void __init ip_static_sysctl_init(void)
2798 {
2799         register_net_sysctl(&init_net, "net/ipv4/route", ipv4_route_table);
2800 }
2801 #endif
2802 

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