xref: /linux/net/ipv4/route.c (revision 6ca80638b90cec66547011ee1ef79e534589989a)
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  * INET		An implementation of the TCP/IP protocol suite for the LINUX
4  *		operating system.  INET is implemented using the  BSD Socket
5  *		interface as the means of communication with the user level.
6  *
7  *		ROUTE - implementation of the IP router.
8  *
9  * Authors:	Ross Biro
10  *		Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
11  *		Alan Cox, <gw4pts@gw4pts.ampr.org>
12  *		Linus Torvalds, <Linus.Torvalds@helsinki.fi>
13  *		Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
14  *
15  * Fixes:
16  *		Alan Cox	:	Verify area fixes.
17  *		Alan Cox	:	cli() protects routing changes
18  *		Rui Oliveira	:	ICMP routing table updates
19  *		(rco@di.uminho.pt)	Routing table insertion and update
20  *		Linus Torvalds	:	Rewrote bits to be sensible
21  *		Alan Cox	:	Added BSD route gw semantics
22  *		Alan Cox	:	Super /proc >4K
23  *		Alan Cox	:	MTU in route table
24  *		Alan Cox	:	MSS actually. Also added the window
25  *					clamper.
26  *		Sam Lantinga	:	Fixed route matching in rt_del()
27  *		Alan Cox	:	Routing cache support.
28  *		Alan Cox	:	Removed compatibility cruft.
29  *		Alan Cox	:	RTF_REJECT support.
30  *		Alan Cox	:	TCP irtt support.
31  *		Jonathan Naylor	:	Added Metric support.
32  *	Miquel van Smoorenburg	:	BSD API fixes.
33  *	Miquel van Smoorenburg	:	Metrics.
34  *		Alan Cox	:	Use __u32 properly
35  *		Alan Cox	:	Aligned routing errors more closely with BSD
36  *					our system is still very different.
37  *		Alan Cox	:	Faster /proc handling
38  *	Alexey Kuznetsov	:	Massive rework to support tree based routing,
39  *					routing caches and better behaviour.
40  *
41  *		Olaf Erb	:	irtt wasn't being copied right.
42  *		Bjorn Ekwall	:	Kerneld route support.
43  *		Alan Cox	:	Multicast fixed (I hope)
44  *		Pavel Krauz	:	Limited broadcast fixed
45  *		Mike McLagan	:	Routing by source
46  *	Alexey Kuznetsov	:	End of old history. Split to fib.c and
47  *					route.c and rewritten from scratch.
48  *		Andi Kleen	:	Load-limit warning messages.
49  *	Vitaly E. Lavrov	:	Transparent proxy revived after year coma.
50  *	Vitaly E. Lavrov	:	Race condition in ip_route_input_slow.
51  *	Tobias Ringstrom	:	Uninitialized res.type in ip_route_output_slow.
52  *	Vladimir V. Ivanov	:	IP rule info (flowid) is really useful.
53  *		Marc Boucher	:	routing by fwmark
54  *	Robert Olsson		:	Added rt_cache statistics
55  *	Arnaldo C. Melo		:	Convert proc stuff to seq_file
56  *	Eric Dumazet		:	hashed spinlocks and rt_check_expire() fixes.
57  *	Ilia Sotnikov		:	Ignore TOS on PMTUD and Redirect
58  *	Ilia Sotnikov		:	Removed TOS from hash calculations
59  */
60 
61 #define pr_fmt(fmt) "IPv4: " fmt
62 
63 #include <linux/module.h>
64 #include <linux/bitops.h>
65 #include <linux/kernel.h>
66 #include <linux/mm.h>
67 #include <linux/memblock.h>
68 #include <linux/socket.h>
69 #include <linux/errno.h>
70 #include <linux/in.h>
71 #include <linux/inet.h>
72 #include <linux/netdevice.h>
73 #include <linux/proc_fs.h>
74 #include <linux/init.h>
75 #include <linux/skbuff.h>
76 #include <linux/inetdevice.h>
77 #include <linux/igmp.h>
78 #include <linux/pkt_sched.h>
79 #include <linux/mroute.h>
80 #include <linux/netfilter_ipv4.h>
81 #include <linux/random.h>
82 #include <linux/rcupdate.h>
83 #include <linux/slab.h>
84 #include <linux/jhash.h>
85 #include <net/dst.h>
86 #include <net/dst_metadata.h>
87 #include <net/inet_dscp.h>
88 #include <net/net_namespace.h>
89 #include <net/ip.h>
90 #include <net/route.h>
91 #include <net/inetpeer.h>
92 #include <net/sock.h>
93 #include <net/ip_fib.h>
94 #include <net/nexthop.h>
95 #include <net/tcp.h>
96 #include <net/icmp.h>
97 #include <net/xfrm.h>
98 #include <net/lwtunnel.h>
99 #include <net/netevent.h>
100 #include <net/rtnetlink.h>
101 #ifdef CONFIG_SYSCTL
102 #include <linux/sysctl.h>
103 #endif
104 #include <net/secure_seq.h>
105 #include <net/ip_tunnels.h>
106 
107 #include "fib_lookup.h"
108 
109 #define RT_FL_TOS(oldflp4) \
110 	((oldflp4)->flowi4_tos & (IPTOS_RT_MASK | RTO_ONLINK))
111 
112 #define RT_GC_TIMEOUT (300*HZ)
113 
114 #define DEFAULT_MIN_PMTU (512 + 20 + 20)
115 #define DEFAULT_MTU_EXPIRES (10 * 60 * HZ)
116 #define DEFAULT_MIN_ADVMSS 256
117 static int ip_rt_max_size;
118 static int ip_rt_redirect_number __read_mostly	= 9;
119 static int ip_rt_redirect_load __read_mostly	= HZ / 50;
120 static int ip_rt_redirect_silence __read_mostly	= ((HZ / 50) << (9 + 1));
121 static int ip_rt_error_cost __read_mostly	= HZ;
122 static int ip_rt_error_burst __read_mostly	= 5 * HZ;
123 
124 static int ip_rt_gc_timeout __read_mostly	= RT_GC_TIMEOUT;
125 
126 /*
127  *	Interface to generic destination cache.
128  */
129 
130 INDIRECT_CALLABLE_SCOPE
131 struct dst_entry	*ipv4_dst_check(struct dst_entry *dst, u32 cookie);
132 static unsigned int	 ipv4_default_advmss(const struct dst_entry *dst);
133 INDIRECT_CALLABLE_SCOPE
134 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 					   bool confirm_neigh);
140 static void		 ip_do_redirect(struct dst_entry *dst, struct sock *sk,
141 					struct sk_buff *skb);
142 static void		ipv4_dst_destroy(struct dst_entry *dst);
143 
144 static u32 *ipv4_cow_metrics(struct dst_entry *dst, unsigned long old)
145 {
146 	WARN_ON(1);
147 	return NULL;
148 }
149 
150 static struct neighbour *ipv4_neigh_lookup(const struct dst_entry *dst,
151 					   struct sk_buff *skb,
152 					   const void *daddr);
153 static void ipv4_confirm_neigh(const struct dst_entry *dst, const void *daddr);
154 
155 static struct dst_ops ipv4_dst_ops = {
156 	.family =		AF_INET,
157 	.check =		ipv4_dst_check,
158 	.default_advmss =	ipv4_default_advmss,
159 	.mtu =			ipv4_mtu,
160 	.cow_metrics =		ipv4_cow_metrics,
161 	.destroy =		ipv4_dst_destroy,
162 	.negative_advice =	ipv4_negative_advice,
163 	.link_failure =		ipv4_link_failure,
164 	.update_pmtu =		ip_rt_update_pmtu,
165 	.redirect =		ip_do_redirect,
166 	.local_out =		__ip_local_out,
167 	.neigh_lookup =		ipv4_neigh_lookup,
168 	.confirm_neigh =	ipv4_confirm_neigh,
169 };
170 
171 #define ECN_OR_COST(class)	TC_PRIO_##class
172 
173 const __u8 ip_tos2prio[16] = {
174 	TC_PRIO_BESTEFFORT,
175 	ECN_OR_COST(BESTEFFORT),
176 	TC_PRIO_BESTEFFORT,
177 	ECN_OR_COST(BESTEFFORT),
178 	TC_PRIO_BULK,
179 	ECN_OR_COST(BULK),
180 	TC_PRIO_BULK,
181 	ECN_OR_COST(BULK),
182 	TC_PRIO_INTERACTIVE,
183 	ECN_OR_COST(INTERACTIVE),
184 	TC_PRIO_INTERACTIVE,
185 	ECN_OR_COST(INTERACTIVE),
186 	TC_PRIO_INTERACTIVE_BULK,
187 	ECN_OR_COST(INTERACTIVE_BULK),
188 	TC_PRIO_INTERACTIVE_BULK,
189 	ECN_OR_COST(INTERACTIVE_BULK)
190 };
191 EXPORT_SYMBOL(ip_tos2prio);
192 
193 static DEFINE_PER_CPU(struct rt_cache_stat, rt_cache_stat);
194 #define RT_CACHE_STAT_INC(field) raw_cpu_inc(rt_cache_stat.field)
195 
196 #ifdef CONFIG_PROC_FS
197 static void *rt_cache_seq_start(struct seq_file *seq, loff_t *pos)
198 {
199 	if (*pos)
200 		return NULL;
201 	return SEQ_START_TOKEN;
202 }
203 
204 static void *rt_cache_seq_next(struct seq_file *seq, void *v, loff_t *pos)
205 {
206 	++*pos;
207 	return NULL;
208 }
209 
210 static void rt_cache_seq_stop(struct seq_file *seq, void *v)
211 {
212 }
213 
214 static int rt_cache_seq_show(struct seq_file *seq, void *v)
215 {
216 	if (v == SEQ_START_TOKEN)
217 		seq_printf(seq, "%-127s\n",
218 			   "Iface\tDestination\tGateway \tFlags\t\tRefCnt\tUse\t"
219 			   "Metric\tSource\t\tMTU\tWindow\tIRTT\tTOS\tHHRef\t"
220 			   "HHUptod\tSpecDst");
221 	return 0;
222 }
223 
224 static const struct seq_operations rt_cache_seq_ops = {
225 	.start  = rt_cache_seq_start,
226 	.next   = rt_cache_seq_next,
227 	.stop   = rt_cache_seq_stop,
228 	.show   = rt_cache_seq_show,
229 };
230 
231 static void *rt_cpu_seq_start(struct seq_file *seq, loff_t *pos)
232 {
233 	int cpu;
234 
235 	if (*pos == 0)
236 		return SEQ_START_TOKEN;
237 
238 	for (cpu = *pos-1; cpu < nr_cpu_ids; ++cpu) {
239 		if (!cpu_possible(cpu))
240 			continue;
241 		*pos = cpu+1;
242 		return &per_cpu(rt_cache_stat, cpu);
243 	}
244 	return NULL;
245 }
246 
247 static void *rt_cpu_seq_next(struct seq_file *seq, void *v, loff_t *pos)
248 {
249 	int cpu;
250 
251 	for (cpu = *pos; cpu < nr_cpu_ids; ++cpu) {
252 		if (!cpu_possible(cpu))
253 			continue;
254 		*pos = cpu+1;
255 		return &per_cpu(rt_cache_stat, cpu);
256 	}
257 	(*pos)++;
258 	return NULL;
259 
260 }
261 
262 static void rt_cpu_seq_stop(struct seq_file *seq, void *v)
263 {
264 
265 }
266 
267 static int rt_cpu_seq_show(struct seq_file *seq, void *v)
268 {
269 	struct rt_cache_stat *st = v;
270 
271 	if (v == SEQ_START_TOKEN) {
272 		seq_puts(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");
273 		return 0;
274 	}
275 
276 	seq_printf(seq, "%08x %08x %08x    %08x   %08x    %08x %08x       "
277 			"%08x       %08x %08x     %08x    %08x %08x   "
278 			"%08x     %08x        %08x        %08x\n",
279 		   dst_entries_get_slow(&ipv4_dst_ops),
280 		   0, /* st->in_hit */
281 		   st->in_slow_tot,
282 		   st->in_slow_mc,
283 		   st->in_no_route,
284 		   st->in_brd,
285 		   st->in_martian_dst,
286 		   st->in_martian_src,
287 
288 		   0, /* st->out_hit */
289 		   st->out_slow_tot,
290 		   st->out_slow_mc,
291 
292 		   0, /* st->gc_total */
293 		   0, /* st->gc_ignored */
294 		   0, /* st->gc_goal_miss */
295 		   0, /* st->gc_dst_overflow */
296 		   0, /* st->in_hlist_search */
297 		   0  /* st->out_hlist_search */
298 		);
299 	return 0;
300 }
301 
302 static const struct seq_operations rt_cpu_seq_ops = {
303 	.start  = rt_cpu_seq_start,
304 	.next   = rt_cpu_seq_next,
305 	.stop   = rt_cpu_seq_stop,
306 	.show   = rt_cpu_seq_show,
307 };
308 
309 #ifdef CONFIG_IP_ROUTE_CLASSID
310 static int rt_acct_proc_show(struct seq_file *m, void *v)
311 {
312 	struct ip_rt_acct *dst, *src;
313 	unsigned int i, j;
314 
315 	dst = kcalloc(256, sizeof(struct ip_rt_acct), GFP_KERNEL);
316 	if (!dst)
317 		return -ENOMEM;
318 
319 	for_each_possible_cpu(i) {
320 		src = (struct ip_rt_acct *)per_cpu_ptr(ip_rt_acct, i);
321 		for (j = 0; j < 256; j++) {
322 			dst[j].o_bytes   += src[j].o_bytes;
323 			dst[j].o_packets += src[j].o_packets;
324 			dst[j].i_bytes   += src[j].i_bytes;
325 			dst[j].i_packets += src[j].i_packets;
326 		}
327 	}
328 
329 	seq_write(m, dst, 256 * sizeof(struct ip_rt_acct));
330 	kfree(dst);
331 	return 0;
332 }
333 #endif
334 
335 static int __net_init ip_rt_do_proc_init(struct net *net)
336 {
337 	struct proc_dir_entry *pde;
338 
339 	pde = proc_create_seq("rt_cache", 0444, net->proc_net,
340 			      &rt_cache_seq_ops);
341 	if (!pde)
342 		goto err1;
343 
344 	pde = proc_create_seq("rt_cache", 0444, net->proc_net_stat,
345 			      &rt_cpu_seq_ops);
346 	if (!pde)
347 		goto err2;
348 
349 #ifdef CONFIG_IP_ROUTE_CLASSID
350 	pde = proc_create_single("rt_acct", 0, net->proc_net,
351 			rt_acct_proc_show);
352 	if (!pde)
353 		goto err3;
354 #endif
355 	return 0;
356 
357 #ifdef CONFIG_IP_ROUTE_CLASSID
358 err3:
359 	remove_proc_entry("rt_cache", net->proc_net_stat);
360 #endif
361 err2:
362 	remove_proc_entry("rt_cache", net->proc_net);
363 err1:
364 	return -ENOMEM;
365 }
366 
367 static void __net_exit ip_rt_do_proc_exit(struct net *net)
368 {
369 	remove_proc_entry("rt_cache", net->proc_net_stat);
370 	remove_proc_entry("rt_cache", net->proc_net);
371 #ifdef CONFIG_IP_ROUTE_CLASSID
372 	remove_proc_entry("rt_acct", net->proc_net);
373 #endif
374 }
375 
376 static struct pernet_operations ip_rt_proc_ops __net_initdata =  {
377 	.init = ip_rt_do_proc_init,
378 	.exit = ip_rt_do_proc_exit,
379 };
380 
381 static int __init ip_rt_proc_init(void)
382 {
383 	return register_pernet_subsys(&ip_rt_proc_ops);
384 }
385 
386 #else
387 static inline int ip_rt_proc_init(void)
388 {
389 	return 0;
390 }
391 #endif /* CONFIG_PROC_FS */
392 
393 static inline bool rt_is_expired(const struct rtable *rth)
394 {
395 	return rth->rt_genid != rt_genid_ipv4(dev_net(rth->dst.dev));
396 }
397 
398 void rt_cache_flush(struct net *net)
399 {
400 	rt_genid_bump_ipv4(net);
401 }
402 
403 static struct neighbour *ipv4_neigh_lookup(const struct dst_entry *dst,
404 					   struct sk_buff *skb,
405 					   const void *daddr)
406 {
407 	const struct rtable *rt = container_of(dst, struct rtable, dst);
408 	struct net_device *dev = dst->dev;
409 	struct neighbour *n;
410 
411 	rcu_read_lock();
412 
413 	if (likely(rt->rt_gw_family == AF_INET)) {
414 		n = ip_neigh_gw4(dev, rt->rt_gw4);
415 	} else if (rt->rt_gw_family == AF_INET6) {
416 		n = ip_neigh_gw6(dev, &rt->rt_gw6);
417         } else {
418 		__be32 pkey;
419 
420 		pkey = skb ? ip_hdr(skb)->daddr : *((__be32 *) daddr);
421 		n = ip_neigh_gw4(dev, pkey);
422 	}
423 
424 	if (!IS_ERR(n) && !refcount_inc_not_zero(&n->refcnt))
425 		n = NULL;
426 
427 	rcu_read_unlock();
428 
429 	return n;
430 }
431 
432 static void ipv4_confirm_neigh(const struct dst_entry *dst, const void *daddr)
433 {
434 	const struct rtable *rt = container_of(dst, struct rtable, dst);
435 	struct net_device *dev = dst->dev;
436 	const __be32 *pkey = daddr;
437 
438 	if (rt->rt_gw_family == AF_INET) {
439 		pkey = (const __be32 *)&rt->rt_gw4;
440 	} else if (rt->rt_gw_family == AF_INET6) {
441 		return __ipv6_confirm_neigh_stub(dev, &rt->rt_gw6);
442 	} else if (!daddr ||
443 		 (rt->rt_flags &
444 		  (RTCF_MULTICAST | RTCF_BROADCAST | RTCF_LOCAL))) {
445 		return;
446 	}
447 	__ipv4_confirm_neigh(dev, *(__force u32 *)pkey);
448 }
449 
450 /* Hash tables of size 2048..262144 depending on RAM size.
451  * Each bucket uses 8 bytes.
452  */
453 static u32 ip_idents_mask __read_mostly;
454 static atomic_t *ip_idents __read_mostly;
455 static u32 *ip_tstamps __read_mostly;
456 
457 /* In order to protect privacy, we add a perturbation to identifiers
458  * if one generator is seldom used. This makes hard for an attacker
459  * to infer how many packets were sent between two points in time.
460  */
461 static u32 ip_idents_reserve(u32 hash, int segs)
462 {
463 	u32 bucket, old, now = (u32)jiffies;
464 	atomic_t *p_id;
465 	u32 *p_tstamp;
466 	u32 delta = 0;
467 
468 	bucket = hash & ip_idents_mask;
469 	p_tstamp = ip_tstamps + bucket;
470 	p_id = ip_idents + bucket;
471 	old = READ_ONCE(*p_tstamp);
472 
473 	if (old != now && cmpxchg(p_tstamp, old, now) == old)
474 		delta = get_random_u32_below(now - old);
475 
476 	/* If UBSAN reports an error there, please make sure your compiler
477 	 * supports -fno-strict-overflow before reporting it that was a bug
478 	 * in UBSAN, and it has been fixed in GCC-8.
479 	 */
480 	return atomic_add_return(segs + delta, p_id) - segs;
481 }
482 
483 void __ip_select_ident(struct net *net, struct iphdr *iph, int segs)
484 {
485 	u32 hash, id;
486 
487 	/* Note the following code is not safe, but this is okay. */
488 	if (unlikely(siphash_key_is_zero(&net->ipv4.ip_id_key)))
489 		get_random_bytes(&net->ipv4.ip_id_key,
490 				 sizeof(net->ipv4.ip_id_key));
491 
492 	hash = siphash_3u32((__force u32)iph->daddr,
493 			    (__force u32)iph->saddr,
494 			    iph->protocol,
495 			    &net->ipv4.ip_id_key);
496 	id = ip_idents_reserve(hash, segs);
497 	iph->id = htons(id);
498 }
499 EXPORT_SYMBOL(__ip_select_ident);
500 
501 static void ip_rt_fix_tos(struct flowi4 *fl4)
502 {
503 	__u8 tos = RT_FL_TOS(fl4);
504 
505 	fl4->flowi4_tos = tos & IPTOS_RT_MASK;
506 	if (tos & RTO_ONLINK)
507 		fl4->flowi4_scope = RT_SCOPE_LINK;
508 }
509 
510 static void __build_flow_key(const struct net *net, struct flowi4 *fl4,
511 			     const struct sock *sk, const struct iphdr *iph,
512 			     int oif, __u8 tos, u8 prot, u32 mark,
513 			     int flow_flags)
514 {
515 	__u8 scope = RT_SCOPE_UNIVERSE;
516 
517 	if (sk) {
518 		oif = sk->sk_bound_dev_if;
519 		mark = READ_ONCE(sk->sk_mark);
520 		tos = ip_sock_rt_tos(sk);
521 		scope = ip_sock_rt_scope(sk);
522 		prot = inet_test_bit(HDRINCL, sk) ? IPPROTO_RAW :
523 						    sk->sk_protocol;
524 	}
525 
526 	flowi4_init_output(fl4, oif, mark, tos & IPTOS_RT_MASK, scope,
527 			   prot, flow_flags, iph->daddr, iph->saddr, 0, 0,
528 			   sock_net_uid(net, sk));
529 }
530 
531 static void build_skb_flow_key(struct flowi4 *fl4, const struct sk_buff *skb,
532 			       const struct sock *sk)
533 {
534 	const struct net *net = dev_net(skb->dev);
535 	const struct iphdr *iph = ip_hdr(skb);
536 	int oif = skb->dev->ifindex;
537 	u8 prot = iph->protocol;
538 	u32 mark = skb->mark;
539 	__u8 tos = iph->tos;
540 
541 	__build_flow_key(net, fl4, sk, iph, oif, tos, prot, mark, 0);
542 }
543 
544 static void build_sk_flow_key(struct flowi4 *fl4, const struct sock *sk)
545 {
546 	const struct inet_sock *inet = inet_sk(sk);
547 	const struct ip_options_rcu *inet_opt;
548 	__be32 daddr = inet->inet_daddr;
549 
550 	rcu_read_lock();
551 	inet_opt = rcu_dereference(inet->inet_opt);
552 	if (inet_opt && inet_opt->opt.srr)
553 		daddr = inet_opt->opt.faddr;
554 	flowi4_init_output(fl4, sk->sk_bound_dev_if, READ_ONCE(sk->sk_mark),
555 			   ip_sock_rt_tos(sk) & IPTOS_RT_MASK,
556 			   ip_sock_rt_scope(sk),
557 			   inet_test_bit(HDRINCL, sk) ?
558 				IPPROTO_RAW : sk->sk_protocol,
559 			   inet_sk_flowi_flags(sk),
560 			   daddr, inet->inet_saddr, 0, 0, sk->sk_uid);
561 	rcu_read_unlock();
562 }
563 
564 static void ip_rt_build_flow_key(struct flowi4 *fl4, const struct sock *sk,
565 				 const struct sk_buff *skb)
566 {
567 	if (skb)
568 		build_skb_flow_key(fl4, skb, sk);
569 	else
570 		build_sk_flow_key(fl4, sk);
571 }
572 
573 static DEFINE_SPINLOCK(fnhe_lock);
574 
575 static void fnhe_flush_routes(struct fib_nh_exception *fnhe)
576 {
577 	struct rtable *rt;
578 
579 	rt = rcu_dereference(fnhe->fnhe_rth_input);
580 	if (rt) {
581 		RCU_INIT_POINTER(fnhe->fnhe_rth_input, NULL);
582 		dst_dev_put(&rt->dst);
583 		dst_release(&rt->dst);
584 	}
585 	rt = rcu_dereference(fnhe->fnhe_rth_output);
586 	if (rt) {
587 		RCU_INIT_POINTER(fnhe->fnhe_rth_output, NULL);
588 		dst_dev_put(&rt->dst);
589 		dst_release(&rt->dst);
590 	}
591 }
592 
593 static void fnhe_remove_oldest(struct fnhe_hash_bucket *hash)
594 {
595 	struct fib_nh_exception __rcu **fnhe_p, **oldest_p;
596 	struct fib_nh_exception *fnhe, *oldest = NULL;
597 
598 	for (fnhe_p = &hash->chain; ; fnhe_p = &fnhe->fnhe_next) {
599 		fnhe = rcu_dereference_protected(*fnhe_p,
600 						 lockdep_is_held(&fnhe_lock));
601 		if (!fnhe)
602 			break;
603 		if (!oldest ||
604 		    time_before(fnhe->fnhe_stamp, oldest->fnhe_stamp)) {
605 			oldest = fnhe;
606 			oldest_p = fnhe_p;
607 		}
608 	}
609 	fnhe_flush_routes(oldest);
610 	*oldest_p = oldest->fnhe_next;
611 	kfree_rcu(oldest, rcu);
612 }
613 
614 static u32 fnhe_hashfun(__be32 daddr)
615 {
616 	static siphash_aligned_key_t fnhe_hash_key;
617 	u64 hval;
618 
619 	net_get_random_once(&fnhe_hash_key, sizeof(fnhe_hash_key));
620 	hval = siphash_1u32((__force u32)daddr, &fnhe_hash_key);
621 	return hash_64(hval, FNHE_HASH_SHIFT);
622 }
623 
624 static void fill_route_from_fnhe(struct rtable *rt, struct fib_nh_exception *fnhe)
625 {
626 	rt->rt_pmtu = fnhe->fnhe_pmtu;
627 	rt->rt_mtu_locked = fnhe->fnhe_mtu_locked;
628 	rt->dst.expires = fnhe->fnhe_expires;
629 
630 	if (fnhe->fnhe_gw) {
631 		rt->rt_flags |= RTCF_REDIRECTED;
632 		rt->rt_uses_gateway = 1;
633 		rt->rt_gw_family = AF_INET;
634 		rt->rt_gw4 = fnhe->fnhe_gw;
635 	}
636 }
637 
638 static void update_or_create_fnhe(struct fib_nh_common *nhc, __be32 daddr,
639 				  __be32 gw, u32 pmtu, bool lock,
640 				  unsigned long expires)
641 {
642 	struct fnhe_hash_bucket *hash;
643 	struct fib_nh_exception *fnhe;
644 	struct rtable *rt;
645 	u32 genid, hval;
646 	unsigned int i;
647 	int depth;
648 
649 	genid = fnhe_genid(dev_net(nhc->nhc_dev));
650 	hval = fnhe_hashfun(daddr);
651 
652 	spin_lock_bh(&fnhe_lock);
653 
654 	hash = rcu_dereference(nhc->nhc_exceptions);
655 	if (!hash) {
656 		hash = kcalloc(FNHE_HASH_SIZE, sizeof(*hash), GFP_ATOMIC);
657 		if (!hash)
658 			goto out_unlock;
659 		rcu_assign_pointer(nhc->nhc_exceptions, hash);
660 	}
661 
662 	hash += hval;
663 
664 	depth = 0;
665 	for (fnhe = rcu_dereference(hash->chain); fnhe;
666 	     fnhe = rcu_dereference(fnhe->fnhe_next)) {
667 		if (fnhe->fnhe_daddr == daddr)
668 			break;
669 		depth++;
670 	}
671 
672 	if (fnhe) {
673 		if (fnhe->fnhe_genid != genid)
674 			fnhe->fnhe_genid = genid;
675 		if (gw)
676 			fnhe->fnhe_gw = gw;
677 		if (pmtu) {
678 			fnhe->fnhe_pmtu = pmtu;
679 			fnhe->fnhe_mtu_locked = lock;
680 		}
681 		fnhe->fnhe_expires = max(1UL, expires);
682 		/* Update all cached dsts too */
683 		rt = rcu_dereference(fnhe->fnhe_rth_input);
684 		if (rt)
685 			fill_route_from_fnhe(rt, fnhe);
686 		rt = rcu_dereference(fnhe->fnhe_rth_output);
687 		if (rt)
688 			fill_route_from_fnhe(rt, fnhe);
689 	} else {
690 		/* Randomize max depth to avoid some side channels attacks. */
691 		int max_depth = FNHE_RECLAIM_DEPTH +
692 				get_random_u32_below(FNHE_RECLAIM_DEPTH);
693 
694 		while (depth > max_depth) {
695 			fnhe_remove_oldest(hash);
696 			depth--;
697 		}
698 
699 		fnhe = kzalloc(sizeof(*fnhe), GFP_ATOMIC);
700 		if (!fnhe)
701 			goto out_unlock;
702 
703 		fnhe->fnhe_next = hash->chain;
704 
705 		fnhe->fnhe_genid = genid;
706 		fnhe->fnhe_daddr = daddr;
707 		fnhe->fnhe_gw = gw;
708 		fnhe->fnhe_pmtu = pmtu;
709 		fnhe->fnhe_mtu_locked = lock;
710 		fnhe->fnhe_expires = max(1UL, expires);
711 
712 		rcu_assign_pointer(hash->chain, fnhe);
713 
714 		/* Exception created; mark the cached routes for the nexthop
715 		 * stale, so anyone caching it rechecks if this exception
716 		 * applies to them.
717 		 */
718 		rt = rcu_dereference(nhc->nhc_rth_input);
719 		if (rt)
720 			rt->dst.obsolete = DST_OBSOLETE_KILL;
721 
722 		for_each_possible_cpu(i) {
723 			struct rtable __rcu **prt;
724 
725 			prt = per_cpu_ptr(nhc->nhc_pcpu_rth_output, i);
726 			rt = rcu_dereference(*prt);
727 			if (rt)
728 				rt->dst.obsolete = DST_OBSOLETE_KILL;
729 		}
730 	}
731 
732 	fnhe->fnhe_stamp = jiffies;
733 
734 out_unlock:
735 	spin_unlock_bh(&fnhe_lock);
736 }
737 
738 static void __ip_do_redirect(struct rtable *rt, struct sk_buff *skb, struct flowi4 *fl4,
739 			     bool kill_route)
740 {
741 	__be32 new_gw = icmp_hdr(skb)->un.gateway;
742 	__be32 old_gw = ip_hdr(skb)->saddr;
743 	struct net_device *dev = skb->dev;
744 	struct in_device *in_dev;
745 	struct fib_result res;
746 	struct neighbour *n;
747 	struct net *net;
748 
749 	switch (icmp_hdr(skb)->code & 7) {
750 	case ICMP_REDIR_NET:
751 	case ICMP_REDIR_NETTOS:
752 	case ICMP_REDIR_HOST:
753 	case ICMP_REDIR_HOSTTOS:
754 		break;
755 
756 	default:
757 		return;
758 	}
759 
760 	if (rt->rt_gw_family != AF_INET || rt->rt_gw4 != old_gw)
761 		return;
762 
763 	in_dev = __in_dev_get_rcu(dev);
764 	if (!in_dev)
765 		return;
766 
767 	net = dev_net(dev);
768 	if (new_gw == old_gw || !IN_DEV_RX_REDIRECTS(in_dev) ||
769 	    ipv4_is_multicast(new_gw) || ipv4_is_lbcast(new_gw) ||
770 	    ipv4_is_zeronet(new_gw))
771 		goto reject_redirect;
772 
773 	if (!IN_DEV_SHARED_MEDIA(in_dev)) {
774 		if (!inet_addr_onlink(in_dev, new_gw, old_gw))
775 			goto reject_redirect;
776 		if (IN_DEV_SEC_REDIRECTS(in_dev) && ip_fib_check_default(new_gw, dev))
777 			goto reject_redirect;
778 	} else {
779 		if (inet_addr_type(net, new_gw) != RTN_UNICAST)
780 			goto reject_redirect;
781 	}
782 
783 	n = __ipv4_neigh_lookup(rt->dst.dev, new_gw);
784 	if (!n)
785 		n = neigh_create(&arp_tbl, &new_gw, rt->dst.dev);
786 	if (!IS_ERR(n)) {
787 		if (!(READ_ONCE(n->nud_state) & NUD_VALID)) {
788 			neigh_event_send(n, NULL);
789 		} else {
790 			if (fib_lookup(net, fl4, &res, 0) == 0) {
791 				struct fib_nh_common *nhc;
792 
793 				fib_select_path(net, &res, fl4, skb);
794 				nhc = FIB_RES_NHC(res);
795 				update_or_create_fnhe(nhc, fl4->daddr, new_gw,
796 						0, false,
797 						jiffies + ip_rt_gc_timeout);
798 			}
799 			if (kill_route)
800 				rt->dst.obsolete = DST_OBSOLETE_KILL;
801 			call_netevent_notifiers(NETEVENT_NEIGH_UPDATE, n);
802 		}
803 		neigh_release(n);
804 	}
805 	return;
806 
807 reject_redirect:
808 #ifdef CONFIG_IP_ROUTE_VERBOSE
809 	if (IN_DEV_LOG_MARTIANS(in_dev)) {
810 		const struct iphdr *iph = (const struct iphdr *) skb->data;
811 		__be32 daddr = iph->daddr;
812 		__be32 saddr = iph->saddr;
813 
814 		net_info_ratelimited("Redirect from %pI4 on %s about %pI4 ignored\n"
815 				     "  Advised path = %pI4 -> %pI4\n",
816 				     &old_gw, dev->name, &new_gw,
817 				     &saddr, &daddr);
818 	}
819 #endif
820 	;
821 }
822 
823 static void ip_do_redirect(struct dst_entry *dst, struct sock *sk, struct sk_buff *skb)
824 {
825 	struct rtable *rt;
826 	struct flowi4 fl4;
827 	const struct iphdr *iph = (const struct iphdr *) skb->data;
828 	struct net *net = dev_net(skb->dev);
829 	int oif = skb->dev->ifindex;
830 	u8 prot = iph->protocol;
831 	u32 mark = skb->mark;
832 	__u8 tos = iph->tos;
833 
834 	rt = (struct rtable *) dst;
835 
836 	__build_flow_key(net, &fl4, sk, iph, oif, tos, prot, mark, 0);
837 	__ip_do_redirect(rt, skb, &fl4, true);
838 }
839 
840 static struct dst_entry *ipv4_negative_advice(struct dst_entry *dst)
841 {
842 	struct rtable *rt = (struct rtable *)dst;
843 	struct dst_entry *ret = dst;
844 
845 	if (rt) {
846 		if (dst->obsolete > 0) {
847 			ip_rt_put(rt);
848 			ret = NULL;
849 		} else if ((rt->rt_flags & RTCF_REDIRECTED) ||
850 			   rt->dst.expires) {
851 			ip_rt_put(rt);
852 			ret = NULL;
853 		}
854 	}
855 	return ret;
856 }
857 
858 /*
859  * Algorithm:
860  *	1. The first ip_rt_redirect_number redirects are sent
861  *	   with exponential backoff, then we stop sending them at all,
862  *	   assuming that the host ignores our redirects.
863  *	2. If we did not see packets requiring redirects
864  *	   during ip_rt_redirect_silence, we assume that the host
865  *	   forgot redirected route and start to send redirects again.
866  *
867  * This algorithm is much cheaper and more intelligent than dumb load limiting
868  * in icmp.c.
869  *
870  * NOTE. Do not forget to inhibit load limiting for redirects (redundant)
871  * and "frag. need" (breaks PMTU discovery) in icmp.c.
872  */
873 
874 void ip_rt_send_redirect(struct sk_buff *skb)
875 {
876 	struct rtable *rt = skb_rtable(skb);
877 	struct in_device *in_dev;
878 	struct inet_peer *peer;
879 	struct net *net;
880 	int log_martians;
881 	int vif;
882 
883 	rcu_read_lock();
884 	in_dev = __in_dev_get_rcu(rt->dst.dev);
885 	if (!in_dev || !IN_DEV_TX_REDIRECTS(in_dev)) {
886 		rcu_read_unlock();
887 		return;
888 	}
889 	log_martians = IN_DEV_LOG_MARTIANS(in_dev);
890 	vif = l3mdev_master_ifindex_rcu(rt->dst.dev);
891 	rcu_read_unlock();
892 
893 	net = dev_net(rt->dst.dev);
894 	peer = inet_getpeer_v4(net->ipv4.peers, ip_hdr(skb)->saddr, vif, 1);
895 	if (!peer) {
896 		icmp_send(skb, ICMP_REDIRECT, ICMP_REDIR_HOST,
897 			  rt_nexthop(rt, ip_hdr(skb)->daddr));
898 		return;
899 	}
900 
901 	/* No redirected packets during ip_rt_redirect_silence;
902 	 * reset the algorithm.
903 	 */
904 	if (time_after(jiffies, peer->rate_last + ip_rt_redirect_silence)) {
905 		peer->rate_tokens = 0;
906 		peer->n_redirects = 0;
907 	}
908 
909 	/* Too many ignored redirects; do not send anything
910 	 * set dst.rate_last to the last seen redirected packet.
911 	 */
912 	if (peer->n_redirects >= ip_rt_redirect_number) {
913 		peer->rate_last = jiffies;
914 		goto out_put_peer;
915 	}
916 
917 	/* Check for load limit; set rate_last to the latest sent
918 	 * redirect.
919 	 */
920 	if (peer->n_redirects == 0 ||
921 	    time_after(jiffies,
922 		       (peer->rate_last +
923 			(ip_rt_redirect_load << peer->n_redirects)))) {
924 		__be32 gw = rt_nexthop(rt, ip_hdr(skb)->daddr);
925 
926 		icmp_send(skb, ICMP_REDIRECT, ICMP_REDIR_HOST, gw);
927 		peer->rate_last = jiffies;
928 		++peer->n_redirects;
929 #ifdef CONFIG_IP_ROUTE_VERBOSE
930 		if (log_martians &&
931 		    peer->n_redirects == ip_rt_redirect_number)
932 			net_warn_ratelimited("host %pI4/if%d ignores redirects for %pI4 to %pI4\n",
933 					     &ip_hdr(skb)->saddr, inet_iif(skb),
934 					     &ip_hdr(skb)->daddr, &gw);
935 #endif
936 	}
937 out_put_peer:
938 	inet_putpeer(peer);
939 }
940 
941 static int ip_error(struct sk_buff *skb)
942 {
943 	struct rtable *rt = skb_rtable(skb);
944 	struct net_device *dev = skb->dev;
945 	struct in_device *in_dev;
946 	struct inet_peer *peer;
947 	unsigned long now;
948 	struct net *net;
949 	SKB_DR(reason);
950 	bool send;
951 	int code;
952 
953 	if (netif_is_l3_master(skb->dev)) {
954 		dev = __dev_get_by_index(dev_net(skb->dev), IPCB(skb)->iif);
955 		if (!dev)
956 			goto out;
957 	}
958 
959 	in_dev = __in_dev_get_rcu(dev);
960 
961 	/* IP on this device is disabled. */
962 	if (!in_dev)
963 		goto out;
964 
965 	net = dev_net(rt->dst.dev);
966 	if (!IN_DEV_FORWARD(in_dev)) {
967 		switch (rt->dst.error) {
968 		case EHOSTUNREACH:
969 			SKB_DR_SET(reason, IP_INADDRERRORS);
970 			__IP_INC_STATS(net, IPSTATS_MIB_INADDRERRORS);
971 			break;
972 
973 		case ENETUNREACH:
974 			SKB_DR_SET(reason, IP_INNOROUTES);
975 			__IP_INC_STATS(net, IPSTATS_MIB_INNOROUTES);
976 			break;
977 		}
978 		goto out;
979 	}
980 
981 	switch (rt->dst.error) {
982 	case EINVAL:
983 	default:
984 		goto out;
985 	case EHOSTUNREACH:
986 		code = ICMP_HOST_UNREACH;
987 		break;
988 	case ENETUNREACH:
989 		code = ICMP_NET_UNREACH;
990 		SKB_DR_SET(reason, IP_INNOROUTES);
991 		__IP_INC_STATS(net, IPSTATS_MIB_INNOROUTES);
992 		break;
993 	case EACCES:
994 		code = ICMP_PKT_FILTERED;
995 		break;
996 	}
997 
998 	peer = inet_getpeer_v4(net->ipv4.peers, ip_hdr(skb)->saddr,
999 			       l3mdev_master_ifindex(skb->dev), 1);
1000 
1001 	send = true;
1002 	if (peer) {
1003 		now = jiffies;
1004 		peer->rate_tokens += now - peer->rate_last;
1005 		if (peer->rate_tokens > ip_rt_error_burst)
1006 			peer->rate_tokens = ip_rt_error_burst;
1007 		peer->rate_last = now;
1008 		if (peer->rate_tokens >= ip_rt_error_cost)
1009 			peer->rate_tokens -= ip_rt_error_cost;
1010 		else
1011 			send = false;
1012 		inet_putpeer(peer);
1013 	}
1014 	if (send)
1015 		icmp_send(skb, ICMP_DEST_UNREACH, code, 0);
1016 
1017 out:	kfree_skb_reason(skb, reason);
1018 	return 0;
1019 }
1020 
1021 static void __ip_rt_update_pmtu(struct rtable *rt, struct flowi4 *fl4, u32 mtu)
1022 {
1023 	struct dst_entry *dst = &rt->dst;
1024 	struct net *net = dev_net(dst->dev);
1025 	struct fib_result res;
1026 	bool lock = false;
1027 	u32 old_mtu;
1028 
1029 	if (ip_mtu_locked(dst))
1030 		return;
1031 
1032 	old_mtu = ipv4_mtu(dst);
1033 	if (old_mtu < mtu)
1034 		return;
1035 
1036 	if (mtu < net->ipv4.ip_rt_min_pmtu) {
1037 		lock = true;
1038 		mtu = min(old_mtu, net->ipv4.ip_rt_min_pmtu);
1039 	}
1040 
1041 	if (rt->rt_pmtu == mtu && !lock &&
1042 	    time_before(jiffies, dst->expires - net->ipv4.ip_rt_mtu_expires / 2))
1043 		return;
1044 
1045 	rcu_read_lock();
1046 	if (fib_lookup(net, fl4, &res, 0) == 0) {
1047 		struct fib_nh_common *nhc;
1048 
1049 		fib_select_path(net, &res, fl4, NULL);
1050 		nhc = FIB_RES_NHC(res);
1051 		update_or_create_fnhe(nhc, fl4->daddr, 0, mtu, lock,
1052 				      jiffies + net->ipv4.ip_rt_mtu_expires);
1053 	}
1054 	rcu_read_unlock();
1055 }
1056 
1057 static void ip_rt_update_pmtu(struct dst_entry *dst, struct sock *sk,
1058 			      struct sk_buff *skb, u32 mtu,
1059 			      bool confirm_neigh)
1060 {
1061 	struct rtable *rt = (struct rtable *) dst;
1062 	struct flowi4 fl4;
1063 
1064 	ip_rt_build_flow_key(&fl4, sk, skb);
1065 
1066 	/* Don't make lookup fail for bridged encapsulations */
1067 	if (skb && netif_is_any_bridge_port(skb->dev))
1068 		fl4.flowi4_oif = 0;
1069 
1070 	__ip_rt_update_pmtu(rt, &fl4, mtu);
1071 }
1072 
1073 void ipv4_update_pmtu(struct sk_buff *skb, struct net *net, u32 mtu,
1074 		      int oif, u8 protocol)
1075 {
1076 	const struct iphdr *iph = (const struct iphdr *)skb->data;
1077 	struct flowi4 fl4;
1078 	struct rtable *rt;
1079 	u32 mark = IP4_REPLY_MARK(net, skb->mark);
1080 
1081 	__build_flow_key(net, &fl4, NULL, iph, oif, iph->tos, protocol, mark,
1082 			 0);
1083 	rt = __ip_route_output_key(net, &fl4);
1084 	if (!IS_ERR(rt)) {
1085 		__ip_rt_update_pmtu(rt, &fl4, mtu);
1086 		ip_rt_put(rt);
1087 	}
1088 }
1089 EXPORT_SYMBOL_GPL(ipv4_update_pmtu);
1090 
1091 static void __ipv4_sk_update_pmtu(struct sk_buff *skb, struct sock *sk, u32 mtu)
1092 {
1093 	const struct iphdr *iph = (const struct iphdr *)skb->data;
1094 	struct flowi4 fl4;
1095 	struct rtable *rt;
1096 
1097 	__build_flow_key(sock_net(sk), &fl4, sk, iph, 0, 0, 0, 0, 0);
1098 
1099 	if (!fl4.flowi4_mark)
1100 		fl4.flowi4_mark = IP4_REPLY_MARK(sock_net(sk), skb->mark);
1101 
1102 	rt = __ip_route_output_key(sock_net(sk), &fl4);
1103 	if (!IS_ERR(rt)) {
1104 		__ip_rt_update_pmtu(rt, &fl4, mtu);
1105 		ip_rt_put(rt);
1106 	}
1107 }
1108 
1109 void ipv4_sk_update_pmtu(struct sk_buff *skb, struct sock *sk, u32 mtu)
1110 {
1111 	const struct iphdr *iph = (const struct iphdr *)skb->data;
1112 	struct flowi4 fl4;
1113 	struct rtable *rt;
1114 	struct dst_entry *odst = NULL;
1115 	bool new = false;
1116 	struct net *net = sock_net(sk);
1117 
1118 	bh_lock_sock(sk);
1119 
1120 	if (!ip_sk_accept_pmtu(sk))
1121 		goto out;
1122 
1123 	odst = sk_dst_get(sk);
1124 
1125 	if (sock_owned_by_user(sk) || !odst) {
1126 		__ipv4_sk_update_pmtu(skb, sk, mtu);
1127 		goto out;
1128 	}
1129 
1130 	__build_flow_key(net, &fl4, sk, iph, 0, 0, 0, 0, 0);
1131 
1132 	rt = (struct rtable *)odst;
1133 	if (odst->obsolete && !odst->ops->check(odst, 0)) {
1134 		rt = ip_route_output_flow(sock_net(sk), &fl4, sk);
1135 		if (IS_ERR(rt))
1136 			goto out;
1137 
1138 		new = true;
1139 	}
1140 
1141 	__ip_rt_update_pmtu((struct rtable *)xfrm_dst_path(&rt->dst), &fl4, mtu);
1142 
1143 	if (!dst_check(&rt->dst, 0)) {
1144 		if (new)
1145 			dst_release(&rt->dst);
1146 
1147 		rt = ip_route_output_flow(sock_net(sk), &fl4, sk);
1148 		if (IS_ERR(rt))
1149 			goto out;
1150 
1151 		new = true;
1152 	}
1153 
1154 	if (new)
1155 		sk_dst_set(sk, &rt->dst);
1156 
1157 out:
1158 	bh_unlock_sock(sk);
1159 	dst_release(odst);
1160 }
1161 EXPORT_SYMBOL_GPL(ipv4_sk_update_pmtu);
1162 
1163 void ipv4_redirect(struct sk_buff *skb, struct net *net,
1164 		   int oif, u8 protocol)
1165 {
1166 	const struct iphdr *iph = (const struct iphdr *)skb->data;
1167 	struct flowi4 fl4;
1168 	struct rtable *rt;
1169 
1170 	__build_flow_key(net, &fl4, NULL, iph, oif, iph->tos, protocol, 0, 0);
1171 	rt = __ip_route_output_key(net, &fl4);
1172 	if (!IS_ERR(rt)) {
1173 		__ip_do_redirect(rt, skb, &fl4, false);
1174 		ip_rt_put(rt);
1175 	}
1176 }
1177 EXPORT_SYMBOL_GPL(ipv4_redirect);
1178 
1179 void ipv4_sk_redirect(struct sk_buff *skb, struct sock *sk)
1180 {
1181 	const struct iphdr *iph = (const struct iphdr *)skb->data;
1182 	struct flowi4 fl4;
1183 	struct rtable *rt;
1184 	struct net *net = sock_net(sk);
1185 
1186 	__build_flow_key(net, &fl4, sk, iph, 0, 0, 0, 0, 0);
1187 	rt = __ip_route_output_key(net, &fl4);
1188 	if (!IS_ERR(rt)) {
1189 		__ip_do_redirect(rt, skb, &fl4, false);
1190 		ip_rt_put(rt);
1191 	}
1192 }
1193 EXPORT_SYMBOL_GPL(ipv4_sk_redirect);
1194 
1195 INDIRECT_CALLABLE_SCOPE struct dst_entry *ipv4_dst_check(struct dst_entry *dst,
1196 							 u32 cookie)
1197 {
1198 	struct rtable *rt = (struct rtable *) dst;
1199 
1200 	/* All IPV4 dsts are created with ->obsolete set to the value
1201 	 * DST_OBSOLETE_FORCE_CHK which forces validation calls down
1202 	 * into this function always.
1203 	 *
1204 	 * When a PMTU/redirect information update invalidates a route,
1205 	 * this is indicated by setting obsolete to DST_OBSOLETE_KILL or
1206 	 * DST_OBSOLETE_DEAD.
1207 	 */
1208 	if (dst->obsolete != DST_OBSOLETE_FORCE_CHK || rt_is_expired(rt))
1209 		return NULL;
1210 	return dst;
1211 }
1212 EXPORT_INDIRECT_CALLABLE(ipv4_dst_check);
1213 
1214 static void ipv4_send_dest_unreach(struct sk_buff *skb)
1215 {
1216 	struct net_device *dev;
1217 	struct ip_options opt;
1218 	int res;
1219 
1220 	/* Recompile ip options since IPCB may not be valid anymore.
1221 	 * Also check we have a reasonable ipv4 header.
1222 	 */
1223 	if (!pskb_network_may_pull(skb, sizeof(struct iphdr)) ||
1224 	    ip_hdr(skb)->version != 4 || ip_hdr(skb)->ihl < 5)
1225 		return;
1226 
1227 	memset(&opt, 0, sizeof(opt));
1228 	if (ip_hdr(skb)->ihl > 5) {
1229 		if (!pskb_network_may_pull(skb, ip_hdr(skb)->ihl * 4))
1230 			return;
1231 		opt.optlen = ip_hdr(skb)->ihl * 4 - sizeof(struct iphdr);
1232 
1233 		rcu_read_lock();
1234 		dev = skb->dev ? skb->dev : skb_rtable(skb)->dst.dev;
1235 		res = __ip_options_compile(dev_net(dev), &opt, skb, NULL);
1236 		rcu_read_unlock();
1237 
1238 		if (res)
1239 			return;
1240 	}
1241 	__icmp_send(skb, ICMP_DEST_UNREACH, ICMP_HOST_UNREACH, 0, &opt);
1242 }
1243 
1244 static void ipv4_link_failure(struct sk_buff *skb)
1245 {
1246 	struct rtable *rt;
1247 
1248 	ipv4_send_dest_unreach(skb);
1249 
1250 	rt = skb_rtable(skb);
1251 	if (rt)
1252 		dst_set_expires(&rt->dst, 0);
1253 }
1254 
1255 static int ip_rt_bug(struct net *net, struct sock *sk, struct sk_buff *skb)
1256 {
1257 	pr_debug("%s: %pI4 -> %pI4, %s\n",
1258 		 __func__, &ip_hdr(skb)->saddr, &ip_hdr(skb)->daddr,
1259 		 skb->dev ? skb->dev->name : "?");
1260 	kfree_skb(skb);
1261 	WARN_ON(1);
1262 	return 0;
1263 }
1264 
1265 /*
1266  * We do not cache source address of outgoing interface,
1267  * because it is used only by IP RR, TS and SRR options,
1268  * so that it out of fast path.
1269  *
1270  * BTW remember: "addr" is allowed to be not aligned
1271  * in IP options!
1272  */
1273 
1274 void ip_rt_get_source(u8 *addr, struct sk_buff *skb, struct rtable *rt)
1275 {
1276 	__be32 src;
1277 
1278 	if (rt_is_output_route(rt))
1279 		src = ip_hdr(skb)->saddr;
1280 	else {
1281 		struct fib_result res;
1282 		struct iphdr *iph = ip_hdr(skb);
1283 		struct flowi4 fl4 = {
1284 			.daddr = iph->daddr,
1285 			.saddr = iph->saddr,
1286 			.flowi4_tos = RT_TOS(iph->tos),
1287 			.flowi4_oif = rt->dst.dev->ifindex,
1288 			.flowi4_iif = skb->dev->ifindex,
1289 			.flowi4_mark = skb->mark,
1290 		};
1291 
1292 		rcu_read_lock();
1293 		if (fib_lookup(dev_net(rt->dst.dev), &fl4, &res, 0) == 0)
1294 			src = fib_result_prefsrc(dev_net(rt->dst.dev), &res);
1295 		else
1296 			src = inet_select_addr(rt->dst.dev,
1297 					       rt_nexthop(rt, iph->daddr),
1298 					       RT_SCOPE_UNIVERSE);
1299 		rcu_read_unlock();
1300 	}
1301 	memcpy(addr, &src, 4);
1302 }
1303 
1304 #ifdef CONFIG_IP_ROUTE_CLASSID
1305 static void set_class_tag(struct rtable *rt, u32 tag)
1306 {
1307 	if (!(rt->dst.tclassid & 0xFFFF))
1308 		rt->dst.tclassid |= tag & 0xFFFF;
1309 	if (!(rt->dst.tclassid & 0xFFFF0000))
1310 		rt->dst.tclassid |= tag & 0xFFFF0000;
1311 }
1312 #endif
1313 
1314 static unsigned int ipv4_default_advmss(const struct dst_entry *dst)
1315 {
1316 	struct net *net = dev_net(dst->dev);
1317 	unsigned int header_size = sizeof(struct tcphdr) + sizeof(struct iphdr);
1318 	unsigned int advmss = max_t(unsigned int, ipv4_mtu(dst) - header_size,
1319 				    net->ipv4.ip_rt_min_advmss);
1320 
1321 	return min(advmss, IPV4_MAX_PMTU - header_size);
1322 }
1323 
1324 INDIRECT_CALLABLE_SCOPE unsigned int ipv4_mtu(const struct dst_entry *dst)
1325 {
1326 	return ip_dst_mtu_maybe_forward(dst, false);
1327 }
1328 EXPORT_INDIRECT_CALLABLE(ipv4_mtu);
1329 
1330 static void ip_del_fnhe(struct fib_nh_common *nhc, __be32 daddr)
1331 {
1332 	struct fnhe_hash_bucket *hash;
1333 	struct fib_nh_exception *fnhe, __rcu **fnhe_p;
1334 	u32 hval = fnhe_hashfun(daddr);
1335 
1336 	spin_lock_bh(&fnhe_lock);
1337 
1338 	hash = rcu_dereference_protected(nhc->nhc_exceptions,
1339 					 lockdep_is_held(&fnhe_lock));
1340 	hash += hval;
1341 
1342 	fnhe_p = &hash->chain;
1343 	fnhe = rcu_dereference_protected(*fnhe_p, lockdep_is_held(&fnhe_lock));
1344 	while (fnhe) {
1345 		if (fnhe->fnhe_daddr == daddr) {
1346 			rcu_assign_pointer(*fnhe_p, rcu_dereference_protected(
1347 				fnhe->fnhe_next, lockdep_is_held(&fnhe_lock)));
1348 			/* set fnhe_daddr to 0 to ensure it won't bind with
1349 			 * new dsts in rt_bind_exception().
1350 			 */
1351 			fnhe->fnhe_daddr = 0;
1352 			fnhe_flush_routes(fnhe);
1353 			kfree_rcu(fnhe, rcu);
1354 			break;
1355 		}
1356 		fnhe_p = &fnhe->fnhe_next;
1357 		fnhe = rcu_dereference_protected(fnhe->fnhe_next,
1358 						 lockdep_is_held(&fnhe_lock));
1359 	}
1360 
1361 	spin_unlock_bh(&fnhe_lock);
1362 }
1363 
1364 static struct fib_nh_exception *find_exception(struct fib_nh_common *nhc,
1365 					       __be32 daddr)
1366 {
1367 	struct fnhe_hash_bucket *hash = rcu_dereference(nhc->nhc_exceptions);
1368 	struct fib_nh_exception *fnhe;
1369 	u32 hval;
1370 
1371 	if (!hash)
1372 		return NULL;
1373 
1374 	hval = fnhe_hashfun(daddr);
1375 
1376 	for (fnhe = rcu_dereference(hash[hval].chain); fnhe;
1377 	     fnhe = rcu_dereference(fnhe->fnhe_next)) {
1378 		if (fnhe->fnhe_daddr == daddr) {
1379 			if (fnhe->fnhe_expires &&
1380 			    time_after(jiffies, fnhe->fnhe_expires)) {
1381 				ip_del_fnhe(nhc, daddr);
1382 				break;
1383 			}
1384 			return fnhe;
1385 		}
1386 	}
1387 	return NULL;
1388 }
1389 
1390 /* MTU selection:
1391  * 1. mtu on route is locked - use it
1392  * 2. mtu from nexthop exception
1393  * 3. mtu from egress device
1394  */
1395 
1396 u32 ip_mtu_from_fib_result(struct fib_result *res, __be32 daddr)
1397 {
1398 	struct fib_nh_common *nhc = res->nhc;
1399 	struct net_device *dev = nhc->nhc_dev;
1400 	struct fib_info *fi = res->fi;
1401 	u32 mtu = 0;
1402 
1403 	if (READ_ONCE(dev_net(dev)->ipv4.sysctl_ip_fwd_use_pmtu) ||
1404 	    fi->fib_metrics->metrics[RTAX_LOCK - 1] & (1 << RTAX_MTU))
1405 		mtu = fi->fib_mtu;
1406 
1407 	if (likely(!mtu)) {
1408 		struct fib_nh_exception *fnhe;
1409 
1410 		fnhe = find_exception(nhc, daddr);
1411 		if (fnhe && !time_after_eq(jiffies, fnhe->fnhe_expires))
1412 			mtu = fnhe->fnhe_pmtu;
1413 	}
1414 
1415 	if (likely(!mtu))
1416 		mtu = min(READ_ONCE(dev->mtu), IP_MAX_MTU);
1417 
1418 	return mtu - lwtunnel_headroom(nhc->nhc_lwtstate, mtu);
1419 }
1420 
1421 static bool rt_bind_exception(struct rtable *rt, struct fib_nh_exception *fnhe,
1422 			      __be32 daddr, const bool do_cache)
1423 {
1424 	bool ret = false;
1425 
1426 	spin_lock_bh(&fnhe_lock);
1427 
1428 	if (daddr == fnhe->fnhe_daddr) {
1429 		struct rtable __rcu **porig;
1430 		struct rtable *orig;
1431 		int genid = fnhe_genid(dev_net(rt->dst.dev));
1432 
1433 		if (rt_is_input_route(rt))
1434 			porig = &fnhe->fnhe_rth_input;
1435 		else
1436 			porig = &fnhe->fnhe_rth_output;
1437 		orig = rcu_dereference(*porig);
1438 
1439 		if (fnhe->fnhe_genid != genid) {
1440 			fnhe->fnhe_genid = genid;
1441 			fnhe->fnhe_gw = 0;
1442 			fnhe->fnhe_pmtu = 0;
1443 			fnhe->fnhe_expires = 0;
1444 			fnhe->fnhe_mtu_locked = false;
1445 			fnhe_flush_routes(fnhe);
1446 			orig = NULL;
1447 		}
1448 		fill_route_from_fnhe(rt, fnhe);
1449 		if (!rt->rt_gw4) {
1450 			rt->rt_gw4 = daddr;
1451 			rt->rt_gw_family = AF_INET;
1452 		}
1453 
1454 		if (do_cache) {
1455 			dst_hold(&rt->dst);
1456 			rcu_assign_pointer(*porig, rt);
1457 			if (orig) {
1458 				dst_dev_put(&orig->dst);
1459 				dst_release(&orig->dst);
1460 			}
1461 			ret = true;
1462 		}
1463 
1464 		fnhe->fnhe_stamp = jiffies;
1465 	}
1466 	spin_unlock_bh(&fnhe_lock);
1467 
1468 	return ret;
1469 }
1470 
1471 static bool rt_cache_route(struct fib_nh_common *nhc, struct rtable *rt)
1472 {
1473 	struct rtable *orig, *prev, **p;
1474 	bool ret = true;
1475 
1476 	if (rt_is_input_route(rt)) {
1477 		p = (struct rtable **)&nhc->nhc_rth_input;
1478 	} else {
1479 		p = (struct rtable **)raw_cpu_ptr(nhc->nhc_pcpu_rth_output);
1480 	}
1481 	orig = *p;
1482 
1483 	/* hold dst before doing cmpxchg() to avoid race condition
1484 	 * on this dst
1485 	 */
1486 	dst_hold(&rt->dst);
1487 	prev = cmpxchg(p, orig, rt);
1488 	if (prev == orig) {
1489 		if (orig) {
1490 			rt_add_uncached_list(orig);
1491 			dst_release(&orig->dst);
1492 		}
1493 	} else {
1494 		dst_release(&rt->dst);
1495 		ret = false;
1496 	}
1497 
1498 	return ret;
1499 }
1500 
1501 struct uncached_list {
1502 	spinlock_t		lock;
1503 	struct list_head	head;
1504 	struct list_head	quarantine;
1505 };
1506 
1507 static DEFINE_PER_CPU_ALIGNED(struct uncached_list, rt_uncached_list);
1508 
1509 void rt_add_uncached_list(struct rtable *rt)
1510 {
1511 	struct uncached_list *ul = raw_cpu_ptr(&rt_uncached_list);
1512 
1513 	rt->dst.rt_uncached_list = ul;
1514 
1515 	spin_lock_bh(&ul->lock);
1516 	list_add_tail(&rt->dst.rt_uncached, &ul->head);
1517 	spin_unlock_bh(&ul->lock);
1518 }
1519 
1520 void rt_del_uncached_list(struct rtable *rt)
1521 {
1522 	if (!list_empty(&rt->dst.rt_uncached)) {
1523 		struct uncached_list *ul = rt->dst.rt_uncached_list;
1524 
1525 		spin_lock_bh(&ul->lock);
1526 		list_del_init(&rt->dst.rt_uncached);
1527 		spin_unlock_bh(&ul->lock);
1528 	}
1529 }
1530 
1531 static void ipv4_dst_destroy(struct dst_entry *dst)
1532 {
1533 	struct rtable *rt = (struct rtable *)dst;
1534 
1535 	ip_dst_metrics_put(dst);
1536 	rt_del_uncached_list(rt);
1537 }
1538 
1539 void rt_flush_dev(struct net_device *dev)
1540 {
1541 	struct rtable *rt, *safe;
1542 	int cpu;
1543 
1544 	for_each_possible_cpu(cpu) {
1545 		struct uncached_list *ul = &per_cpu(rt_uncached_list, cpu);
1546 
1547 		if (list_empty(&ul->head))
1548 			continue;
1549 
1550 		spin_lock_bh(&ul->lock);
1551 		list_for_each_entry_safe(rt, safe, &ul->head, dst.rt_uncached) {
1552 			if (rt->dst.dev != dev)
1553 				continue;
1554 			rt->dst.dev = blackhole_netdev;
1555 			netdev_ref_replace(dev, blackhole_netdev,
1556 					   &rt->dst.dev_tracker, GFP_ATOMIC);
1557 			list_move(&rt->dst.rt_uncached, &ul->quarantine);
1558 		}
1559 		spin_unlock_bh(&ul->lock);
1560 	}
1561 }
1562 
1563 static bool rt_cache_valid(const struct rtable *rt)
1564 {
1565 	return	rt &&
1566 		rt->dst.obsolete == DST_OBSOLETE_FORCE_CHK &&
1567 		!rt_is_expired(rt);
1568 }
1569 
1570 static void rt_set_nexthop(struct rtable *rt, __be32 daddr,
1571 			   const struct fib_result *res,
1572 			   struct fib_nh_exception *fnhe,
1573 			   struct fib_info *fi, u16 type, u32 itag,
1574 			   const bool do_cache)
1575 {
1576 	bool cached = false;
1577 
1578 	if (fi) {
1579 		struct fib_nh_common *nhc = FIB_RES_NHC(*res);
1580 
1581 		if (nhc->nhc_gw_family && nhc->nhc_scope == RT_SCOPE_LINK) {
1582 			rt->rt_uses_gateway = 1;
1583 			rt->rt_gw_family = nhc->nhc_gw_family;
1584 			/* only INET and INET6 are supported */
1585 			if (likely(nhc->nhc_gw_family == AF_INET))
1586 				rt->rt_gw4 = nhc->nhc_gw.ipv4;
1587 			else
1588 				rt->rt_gw6 = nhc->nhc_gw.ipv6;
1589 		}
1590 
1591 		ip_dst_init_metrics(&rt->dst, fi->fib_metrics);
1592 
1593 #ifdef CONFIG_IP_ROUTE_CLASSID
1594 		if (nhc->nhc_family == AF_INET) {
1595 			struct fib_nh *nh;
1596 
1597 			nh = container_of(nhc, struct fib_nh, nh_common);
1598 			rt->dst.tclassid = nh->nh_tclassid;
1599 		}
1600 #endif
1601 		rt->dst.lwtstate = lwtstate_get(nhc->nhc_lwtstate);
1602 		if (unlikely(fnhe))
1603 			cached = rt_bind_exception(rt, fnhe, daddr, do_cache);
1604 		else if (do_cache)
1605 			cached = rt_cache_route(nhc, rt);
1606 		if (unlikely(!cached)) {
1607 			/* Routes we intend to cache in nexthop exception or
1608 			 * FIB nexthop have the DST_NOCACHE bit clear.
1609 			 * However, if we are unsuccessful at storing this
1610 			 * route into the cache we really need to set it.
1611 			 */
1612 			if (!rt->rt_gw4) {
1613 				rt->rt_gw_family = AF_INET;
1614 				rt->rt_gw4 = daddr;
1615 			}
1616 			rt_add_uncached_list(rt);
1617 		}
1618 	} else
1619 		rt_add_uncached_list(rt);
1620 
1621 #ifdef CONFIG_IP_ROUTE_CLASSID
1622 #ifdef CONFIG_IP_MULTIPLE_TABLES
1623 	set_class_tag(rt, res->tclassid);
1624 #endif
1625 	set_class_tag(rt, itag);
1626 #endif
1627 }
1628 
1629 struct rtable *rt_dst_alloc(struct net_device *dev,
1630 			    unsigned int flags, u16 type,
1631 			    bool noxfrm)
1632 {
1633 	struct rtable *rt;
1634 
1635 	rt = dst_alloc(&ipv4_dst_ops, dev, DST_OBSOLETE_FORCE_CHK,
1636 		       (noxfrm ? DST_NOXFRM : 0));
1637 
1638 	if (rt) {
1639 		rt->rt_genid = rt_genid_ipv4(dev_net(dev));
1640 		rt->rt_flags = flags;
1641 		rt->rt_type = type;
1642 		rt->rt_is_input = 0;
1643 		rt->rt_iif = 0;
1644 		rt->rt_pmtu = 0;
1645 		rt->rt_mtu_locked = 0;
1646 		rt->rt_uses_gateway = 0;
1647 		rt->rt_gw_family = 0;
1648 		rt->rt_gw4 = 0;
1649 
1650 		rt->dst.output = ip_output;
1651 		if (flags & RTCF_LOCAL)
1652 			rt->dst.input = ip_local_deliver;
1653 	}
1654 
1655 	return rt;
1656 }
1657 EXPORT_SYMBOL(rt_dst_alloc);
1658 
1659 struct rtable *rt_dst_clone(struct net_device *dev, struct rtable *rt)
1660 {
1661 	struct rtable *new_rt;
1662 
1663 	new_rt = dst_alloc(&ipv4_dst_ops, dev, DST_OBSOLETE_FORCE_CHK,
1664 			   rt->dst.flags);
1665 
1666 	if (new_rt) {
1667 		new_rt->rt_genid = rt_genid_ipv4(dev_net(dev));
1668 		new_rt->rt_flags = rt->rt_flags;
1669 		new_rt->rt_type = rt->rt_type;
1670 		new_rt->rt_is_input = rt->rt_is_input;
1671 		new_rt->rt_iif = rt->rt_iif;
1672 		new_rt->rt_pmtu = rt->rt_pmtu;
1673 		new_rt->rt_mtu_locked = rt->rt_mtu_locked;
1674 		new_rt->rt_gw_family = rt->rt_gw_family;
1675 		if (rt->rt_gw_family == AF_INET)
1676 			new_rt->rt_gw4 = rt->rt_gw4;
1677 		else if (rt->rt_gw_family == AF_INET6)
1678 			new_rt->rt_gw6 = rt->rt_gw6;
1679 
1680 		new_rt->dst.input = rt->dst.input;
1681 		new_rt->dst.output = rt->dst.output;
1682 		new_rt->dst.error = rt->dst.error;
1683 		new_rt->dst.lastuse = jiffies;
1684 		new_rt->dst.lwtstate = lwtstate_get(rt->dst.lwtstate);
1685 	}
1686 	return new_rt;
1687 }
1688 EXPORT_SYMBOL(rt_dst_clone);
1689 
1690 /* called in rcu_read_lock() section */
1691 int ip_mc_validate_source(struct sk_buff *skb, __be32 daddr, __be32 saddr,
1692 			  u8 tos, struct net_device *dev,
1693 			  struct in_device *in_dev, u32 *itag)
1694 {
1695 	int err;
1696 
1697 	/* Primary sanity checks. */
1698 	if (!in_dev)
1699 		return -EINVAL;
1700 
1701 	if (ipv4_is_multicast(saddr) || ipv4_is_lbcast(saddr) ||
1702 	    skb->protocol != htons(ETH_P_IP))
1703 		return -EINVAL;
1704 
1705 	if (ipv4_is_loopback(saddr) && !IN_DEV_ROUTE_LOCALNET(in_dev))
1706 		return -EINVAL;
1707 
1708 	if (ipv4_is_zeronet(saddr)) {
1709 		if (!ipv4_is_local_multicast(daddr) &&
1710 		    ip_hdr(skb)->protocol != IPPROTO_IGMP)
1711 			return -EINVAL;
1712 	} else {
1713 		err = fib_validate_source(skb, saddr, 0, tos, 0, dev,
1714 					  in_dev, itag);
1715 		if (err < 0)
1716 			return err;
1717 	}
1718 	return 0;
1719 }
1720 
1721 /* called in rcu_read_lock() section */
1722 static int ip_route_input_mc(struct sk_buff *skb, __be32 daddr, __be32 saddr,
1723 			     u8 tos, struct net_device *dev, int our)
1724 {
1725 	struct in_device *in_dev = __in_dev_get_rcu(dev);
1726 	unsigned int flags = RTCF_MULTICAST;
1727 	struct rtable *rth;
1728 	u32 itag = 0;
1729 	int err;
1730 
1731 	err = ip_mc_validate_source(skb, daddr, saddr, tos, dev, in_dev, &itag);
1732 	if (err)
1733 		return err;
1734 
1735 	if (our)
1736 		flags |= RTCF_LOCAL;
1737 
1738 	if (IN_DEV_ORCONF(in_dev, NOPOLICY))
1739 		IPCB(skb)->flags |= IPSKB_NOPOLICY;
1740 
1741 	rth = rt_dst_alloc(dev_net(dev)->loopback_dev, flags, RTN_MULTICAST,
1742 			   false);
1743 	if (!rth)
1744 		return -ENOBUFS;
1745 
1746 #ifdef CONFIG_IP_ROUTE_CLASSID
1747 	rth->dst.tclassid = itag;
1748 #endif
1749 	rth->dst.output = ip_rt_bug;
1750 	rth->rt_is_input= 1;
1751 
1752 #ifdef CONFIG_IP_MROUTE
1753 	if (!ipv4_is_local_multicast(daddr) && IN_DEV_MFORWARD(in_dev))
1754 		rth->dst.input = ip_mr_input;
1755 #endif
1756 	RT_CACHE_STAT_INC(in_slow_mc);
1757 
1758 	skb_dst_drop(skb);
1759 	skb_dst_set(skb, &rth->dst);
1760 	return 0;
1761 }
1762 
1763 
1764 static void ip_handle_martian_source(struct net_device *dev,
1765 				     struct in_device *in_dev,
1766 				     struct sk_buff *skb,
1767 				     __be32 daddr,
1768 				     __be32 saddr)
1769 {
1770 	RT_CACHE_STAT_INC(in_martian_src);
1771 #ifdef CONFIG_IP_ROUTE_VERBOSE
1772 	if (IN_DEV_LOG_MARTIANS(in_dev) && net_ratelimit()) {
1773 		/*
1774 		 *	RFC1812 recommendation, if source is martian,
1775 		 *	the only hint is MAC header.
1776 		 */
1777 		pr_warn("martian source %pI4 from %pI4, on dev %s\n",
1778 			&daddr, &saddr, dev->name);
1779 		if (dev->hard_header_len && skb_mac_header_was_set(skb)) {
1780 			print_hex_dump(KERN_WARNING, "ll header: ",
1781 				       DUMP_PREFIX_OFFSET, 16, 1,
1782 				       skb_mac_header(skb),
1783 				       dev->hard_header_len, false);
1784 		}
1785 	}
1786 #endif
1787 }
1788 
1789 /* called in rcu_read_lock() section */
1790 static int __mkroute_input(struct sk_buff *skb,
1791 			   const struct fib_result *res,
1792 			   struct in_device *in_dev,
1793 			   __be32 daddr, __be32 saddr, u32 tos)
1794 {
1795 	struct fib_nh_common *nhc = FIB_RES_NHC(*res);
1796 	struct net_device *dev = nhc->nhc_dev;
1797 	struct fib_nh_exception *fnhe;
1798 	struct rtable *rth;
1799 	int err;
1800 	struct in_device *out_dev;
1801 	bool do_cache;
1802 	u32 itag = 0;
1803 
1804 	/* get a working reference to the output device */
1805 	out_dev = __in_dev_get_rcu(dev);
1806 	if (!out_dev) {
1807 		net_crit_ratelimited("Bug in ip_route_input_slow(). Please report.\n");
1808 		return -EINVAL;
1809 	}
1810 
1811 	err = fib_validate_source(skb, saddr, daddr, tos, FIB_RES_OIF(*res),
1812 				  in_dev->dev, in_dev, &itag);
1813 	if (err < 0) {
1814 		ip_handle_martian_source(in_dev->dev, in_dev, skb, daddr,
1815 					 saddr);
1816 
1817 		goto cleanup;
1818 	}
1819 
1820 	do_cache = res->fi && !itag;
1821 	if (out_dev == in_dev && err && IN_DEV_TX_REDIRECTS(out_dev) &&
1822 	    skb->protocol == htons(ETH_P_IP)) {
1823 		__be32 gw;
1824 
1825 		gw = nhc->nhc_gw_family == AF_INET ? nhc->nhc_gw.ipv4 : 0;
1826 		if (IN_DEV_SHARED_MEDIA(out_dev) ||
1827 		    inet_addr_onlink(out_dev, saddr, gw))
1828 			IPCB(skb)->flags |= IPSKB_DOREDIRECT;
1829 	}
1830 
1831 	if (skb->protocol != htons(ETH_P_IP)) {
1832 		/* Not IP (i.e. ARP). Do not create route, if it is
1833 		 * invalid for proxy arp. DNAT routes are always valid.
1834 		 *
1835 		 * Proxy arp feature have been extended to allow, ARP
1836 		 * replies back to the same interface, to support
1837 		 * Private VLAN switch technologies. See arp.c.
1838 		 */
1839 		if (out_dev == in_dev &&
1840 		    IN_DEV_PROXY_ARP_PVLAN(in_dev) == 0) {
1841 			err = -EINVAL;
1842 			goto cleanup;
1843 		}
1844 	}
1845 
1846 	if (IN_DEV_ORCONF(in_dev, NOPOLICY))
1847 		IPCB(skb)->flags |= IPSKB_NOPOLICY;
1848 
1849 	fnhe = find_exception(nhc, daddr);
1850 	if (do_cache) {
1851 		if (fnhe)
1852 			rth = rcu_dereference(fnhe->fnhe_rth_input);
1853 		else
1854 			rth = rcu_dereference(nhc->nhc_rth_input);
1855 		if (rt_cache_valid(rth)) {
1856 			skb_dst_set_noref(skb, &rth->dst);
1857 			goto out;
1858 		}
1859 	}
1860 
1861 	rth = rt_dst_alloc(out_dev->dev, 0, res->type,
1862 			   IN_DEV_ORCONF(out_dev, NOXFRM));
1863 	if (!rth) {
1864 		err = -ENOBUFS;
1865 		goto cleanup;
1866 	}
1867 
1868 	rth->rt_is_input = 1;
1869 	RT_CACHE_STAT_INC(in_slow_tot);
1870 
1871 	rth->dst.input = ip_forward;
1872 
1873 	rt_set_nexthop(rth, daddr, res, fnhe, res->fi, res->type, itag,
1874 		       do_cache);
1875 	lwtunnel_set_redirect(&rth->dst);
1876 	skb_dst_set(skb, &rth->dst);
1877 out:
1878 	err = 0;
1879  cleanup:
1880 	return err;
1881 }
1882 
1883 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1884 /* To make ICMP packets follow the right flow, the multipath hash is
1885  * calculated from the inner IP addresses.
1886  */
1887 static void ip_multipath_l3_keys(const struct sk_buff *skb,
1888 				 struct flow_keys *hash_keys)
1889 {
1890 	const struct iphdr *outer_iph = ip_hdr(skb);
1891 	const struct iphdr *key_iph = outer_iph;
1892 	const struct iphdr *inner_iph;
1893 	const struct icmphdr *icmph;
1894 	struct iphdr _inner_iph;
1895 	struct icmphdr _icmph;
1896 
1897 	if (likely(outer_iph->protocol != IPPROTO_ICMP))
1898 		goto out;
1899 
1900 	if (unlikely((outer_iph->frag_off & htons(IP_OFFSET)) != 0))
1901 		goto out;
1902 
1903 	icmph = skb_header_pointer(skb, outer_iph->ihl * 4, sizeof(_icmph),
1904 				   &_icmph);
1905 	if (!icmph)
1906 		goto out;
1907 
1908 	if (!icmp_is_err(icmph->type))
1909 		goto out;
1910 
1911 	inner_iph = skb_header_pointer(skb,
1912 				       outer_iph->ihl * 4 + sizeof(_icmph),
1913 				       sizeof(_inner_iph), &_inner_iph);
1914 	if (!inner_iph)
1915 		goto out;
1916 
1917 	key_iph = inner_iph;
1918 out:
1919 	hash_keys->addrs.v4addrs.src = key_iph->saddr;
1920 	hash_keys->addrs.v4addrs.dst = key_iph->daddr;
1921 }
1922 
1923 static u32 fib_multipath_custom_hash_outer(const struct net *net,
1924 					   const struct sk_buff *skb,
1925 					   bool *p_has_inner)
1926 {
1927 	u32 hash_fields = READ_ONCE(net->ipv4.sysctl_fib_multipath_hash_fields);
1928 	struct flow_keys keys, hash_keys;
1929 
1930 	if (!(hash_fields & FIB_MULTIPATH_HASH_FIELD_OUTER_MASK))
1931 		return 0;
1932 
1933 	memset(&hash_keys, 0, sizeof(hash_keys));
1934 	skb_flow_dissect_flow_keys(skb, &keys, FLOW_DISSECTOR_F_STOP_AT_ENCAP);
1935 
1936 	hash_keys.control.addr_type = FLOW_DISSECTOR_KEY_IPV4_ADDRS;
1937 	if (hash_fields & FIB_MULTIPATH_HASH_FIELD_SRC_IP)
1938 		hash_keys.addrs.v4addrs.src = keys.addrs.v4addrs.src;
1939 	if (hash_fields & FIB_MULTIPATH_HASH_FIELD_DST_IP)
1940 		hash_keys.addrs.v4addrs.dst = keys.addrs.v4addrs.dst;
1941 	if (hash_fields & FIB_MULTIPATH_HASH_FIELD_IP_PROTO)
1942 		hash_keys.basic.ip_proto = keys.basic.ip_proto;
1943 	if (hash_fields & FIB_MULTIPATH_HASH_FIELD_SRC_PORT)
1944 		hash_keys.ports.src = keys.ports.src;
1945 	if (hash_fields & FIB_MULTIPATH_HASH_FIELD_DST_PORT)
1946 		hash_keys.ports.dst = keys.ports.dst;
1947 
1948 	*p_has_inner = !!(keys.control.flags & FLOW_DIS_ENCAPSULATION);
1949 	return flow_hash_from_keys(&hash_keys);
1950 }
1951 
1952 static u32 fib_multipath_custom_hash_inner(const struct net *net,
1953 					   const struct sk_buff *skb,
1954 					   bool has_inner)
1955 {
1956 	u32 hash_fields = READ_ONCE(net->ipv4.sysctl_fib_multipath_hash_fields);
1957 	struct flow_keys keys, hash_keys;
1958 
1959 	/* We assume the packet carries an encapsulation, but if none was
1960 	 * encountered during dissection of the outer flow, then there is no
1961 	 * point in calling the flow dissector again.
1962 	 */
1963 	if (!has_inner)
1964 		return 0;
1965 
1966 	if (!(hash_fields & FIB_MULTIPATH_HASH_FIELD_INNER_MASK))
1967 		return 0;
1968 
1969 	memset(&hash_keys, 0, sizeof(hash_keys));
1970 	skb_flow_dissect_flow_keys(skb, &keys, 0);
1971 
1972 	if (!(keys.control.flags & FLOW_DIS_ENCAPSULATION))
1973 		return 0;
1974 
1975 	if (keys.control.addr_type == FLOW_DISSECTOR_KEY_IPV4_ADDRS) {
1976 		hash_keys.control.addr_type = FLOW_DISSECTOR_KEY_IPV4_ADDRS;
1977 		if (hash_fields & FIB_MULTIPATH_HASH_FIELD_INNER_SRC_IP)
1978 			hash_keys.addrs.v4addrs.src = keys.addrs.v4addrs.src;
1979 		if (hash_fields & FIB_MULTIPATH_HASH_FIELD_INNER_DST_IP)
1980 			hash_keys.addrs.v4addrs.dst = keys.addrs.v4addrs.dst;
1981 	} else if (keys.control.addr_type == FLOW_DISSECTOR_KEY_IPV6_ADDRS) {
1982 		hash_keys.control.addr_type = FLOW_DISSECTOR_KEY_IPV6_ADDRS;
1983 		if (hash_fields & FIB_MULTIPATH_HASH_FIELD_INNER_SRC_IP)
1984 			hash_keys.addrs.v6addrs.src = keys.addrs.v6addrs.src;
1985 		if (hash_fields & FIB_MULTIPATH_HASH_FIELD_INNER_DST_IP)
1986 			hash_keys.addrs.v6addrs.dst = keys.addrs.v6addrs.dst;
1987 		if (hash_fields & FIB_MULTIPATH_HASH_FIELD_INNER_FLOWLABEL)
1988 			hash_keys.tags.flow_label = keys.tags.flow_label;
1989 	}
1990 
1991 	if (hash_fields & FIB_MULTIPATH_HASH_FIELD_INNER_IP_PROTO)
1992 		hash_keys.basic.ip_proto = keys.basic.ip_proto;
1993 	if (hash_fields & FIB_MULTIPATH_HASH_FIELD_INNER_SRC_PORT)
1994 		hash_keys.ports.src = keys.ports.src;
1995 	if (hash_fields & FIB_MULTIPATH_HASH_FIELD_INNER_DST_PORT)
1996 		hash_keys.ports.dst = keys.ports.dst;
1997 
1998 	return flow_hash_from_keys(&hash_keys);
1999 }
2000 
2001 static u32 fib_multipath_custom_hash_skb(const struct net *net,
2002 					 const struct sk_buff *skb)
2003 {
2004 	u32 mhash, mhash_inner;
2005 	bool has_inner = true;
2006 
2007 	mhash = fib_multipath_custom_hash_outer(net, skb, &has_inner);
2008 	mhash_inner = fib_multipath_custom_hash_inner(net, skb, has_inner);
2009 
2010 	return jhash_2words(mhash, mhash_inner, 0);
2011 }
2012 
2013 static u32 fib_multipath_custom_hash_fl4(const struct net *net,
2014 					 const struct flowi4 *fl4)
2015 {
2016 	u32 hash_fields = READ_ONCE(net->ipv4.sysctl_fib_multipath_hash_fields);
2017 	struct flow_keys hash_keys;
2018 
2019 	if (!(hash_fields & FIB_MULTIPATH_HASH_FIELD_OUTER_MASK))
2020 		return 0;
2021 
2022 	memset(&hash_keys, 0, sizeof(hash_keys));
2023 	hash_keys.control.addr_type = FLOW_DISSECTOR_KEY_IPV4_ADDRS;
2024 	if (hash_fields & FIB_MULTIPATH_HASH_FIELD_SRC_IP)
2025 		hash_keys.addrs.v4addrs.src = fl4->saddr;
2026 	if (hash_fields & FIB_MULTIPATH_HASH_FIELD_DST_IP)
2027 		hash_keys.addrs.v4addrs.dst = fl4->daddr;
2028 	if (hash_fields & FIB_MULTIPATH_HASH_FIELD_IP_PROTO)
2029 		hash_keys.basic.ip_proto = fl4->flowi4_proto;
2030 	if (hash_fields & FIB_MULTIPATH_HASH_FIELD_SRC_PORT)
2031 		hash_keys.ports.src = fl4->fl4_sport;
2032 	if (hash_fields & FIB_MULTIPATH_HASH_FIELD_DST_PORT)
2033 		hash_keys.ports.dst = fl4->fl4_dport;
2034 
2035 	return flow_hash_from_keys(&hash_keys);
2036 }
2037 
2038 /* if skb is set it will be used and fl4 can be NULL */
2039 int fib_multipath_hash(const struct net *net, const struct flowi4 *fl4,
2040 		       const struct sk_buff *skb, struct flow_keys *flkeys)
2041 {
2042 	u32 multipath_hash = fl4 ? fl4->flowi4_multipath_hash : 0;
2043 	struct flow_keys hash_keys;
2044 	u32 mhash = 0;
2045 
2046 	switch (READ_ONCE(net->ipv4.sysctl_fib_multipath_hash_policy)) {
2047 	case 0:
2048 		memset(&hash_keys, 0, sizeof(hash_keys));
2049 		hash_keys.control.addr_type = FLOW_DISSECTOR_KEY_IPV4_ADDRS;
2050 		if (skb) {
2051 			ip_multipath_l3_keys(skb, &hash_keys);
2052 		} else {
2053 			hash_keys.addrs.v4addrs.src = fl4->saddr;
2054 			hash_keys.addrs.v4addrs.dst = fl4->daddr;
2055 		}
2056 		mhash = flow_hash_from_keys(&hash_keys);
2057 		break;
2058 	case 1:
2059 		/* skb is currently provided only when forwarding */
2060 		if (skb) {
2061 			unsigned int flag = FLOW_DISSECTOR_F_STOP_AT_ENCAP;
2062 			struct flow_keys keys;
2063 
2064 			/* short-circuit if we already have L4 hash present */
2065 			if (skb->l4_hash)
2066 				return skb_get_hash_raw(skb) >> 1;
2067 
2068 			memset(&hash_keys, 0, sizeof(hash_keys));
2069 
2070 			if (!flkeys) {
2071 				skb_flow_dissect_flow_keys(skb, &keys, flag);
2072 				flkeys = &keys;
2073 			}
2074 
2075 			hash_keys.control.addr_type = FLOW_DISSECTOR_KEY_IPV4_ADDRS;
2076 			hash_keys.addrs.v4addrs.src = flkeys->addrs.v4addrs.src;
2077 			hash_keys.addrs.v4addrs.dst = flkeys->addrs.v4addrs.dst;
2078 			hash_keys.ports.src = flkeys->ports.src;
2079 			hash_keys.ports.dst = flkeys->ports.dst;
2080 			hash_keys.basic.ip_proto = flkeys->basic.ip_proto;
2081 		} else {
2082 			memset(&hash_keys, 0, sizeof(hash_keys));
2083 			hash_keys.control.addr_type = FLOW_DISSECTOR_KEY_IPV4_ADDRS;
2084 			hash_keys.addrs.v4addrs.src = fl4->saddr;
2085 			hash_keys.addrs.v4addrs.dst = fl4->daddr;
2086 			hash_keys.ports.src = fl4->fl4_sport;
2087 			hash_keys.ports.dst = fl4->fl4_dport;
2088 			hash_keys.basic.ip_proto = fl4->flowi4_proto;
2089 		}
2090 		mhash = flow_hash_from_keys(&hash_keys);
2091 		break;
2092 	case 2:
2093 		memset(&hash_keys, 0, sizeof(hash_keys));
2094 		/* skb is currently provided only when forwarding */
2095 		if (skb) {
2096 			struct flow_keys keys;
2097 
2098 			skb_flow_dissect_flow_keys(skb, &keys, 0);
2099 			/* Inner can be v4 or v6 */
2100 			if (keys.control.addr_type == FLOW_DISSECTOR_KEY_IPV4_ADDRS) {
2101 				hash_keys.control.addr_type = FLOW_DISSECTOR_KEY_IPV4_ADDRS;
2102 				hash_keys.addrs.v4addrs.src = keys.addrs.v4addrs.src;
2103 				hash_keys.addrs.v4addrs.dst = keys.addrs.v4addrs.dst;
2104 			} else if (keys.control.addr_type == FLOW_DISSECTOR_KEY_IPV6_ADDRS) {
2105 				hash_keys.control.addr_type = FLOW_DISSECTOR_KEY_IPV6_ADDRS;
2106 				hash_keys.addrs.v6addrs.src = keys.addrs.v6addrs.src;
2107 				hash_keys.addrs.v6addrs.dst = keys.addrs.v6addrs.dst;
2108 				hash_keys.tags.flow_label = keys.tags.flow_label;
2109 				hash_keys.basic.ip_proto = keys.basic.ip_proto;
2110 			} else {
2111 				/* Same as case 0 */
2112 				hash_keys.control.addr_type = FLOW_DISSECTOR_KEY_IPV4_ADDRS;
2113 				ip_multipath_l3_keys(skb, &hash_keys);
2114 			}
2115 		} else {
2116 			/* Same as case 0 */
2117 			hash_keys.control.addr_type = FLOW_DISSECTOR_KEY_IPV4_ADDRS;
2118 			hash_keys.addrs.v4addrs.src = fl4->saddr;
2119 			hash_keys.addrs.v4addrs.dst = fl4->daddr;
2120 		}
2121 		mhash = flow_hash_from_keys(&hash_keys);
2122 		break;
2123 	case 3:
2124 		if (skb)
2125 			mhash = fib_multipath_custom_hash_skb(net, skb);
2126 		else
2127 			mhash = fib_multipath_custom_hash_fl4(net, fl4);
2128 		break;
2129 	}
2130 
2131 	if (multipath_hash)
2132 		mhash = jhash_2words(mhash, multipath_hash, 0);
2133 
2134 	return mhash >> 1;
2135 }
2136 #endif /* CONFIG_IP_ROUTE_MULTIPATH */
2137 
2138 static int ip_mkroute_input(struct sk_buff *skb,
2139 			    struct fib_result *res,
2140 			    struct in_device *in_dev,
2141 			    __be32 daddr, __be32 saddr, u32 tos,
2142 			    struct flow_keys *hkeys)
2143 {
2144 #ifdef CONFIG_IP_ROUTE_MULTIPATH
2145 	if (res->fi && fib_info_num_path(res->fi) > 1) {
2146 		int h = fib_multipath_hash(res->fi->fib_net, NULL, skb, hkeys);
2147 
2148 		fib_select_multipath(res, h);
2149 		IPCB(skb)->flags |= IPSKB_MULTIPATH;
2150 	}
2151 #endif
2152 
2153 	/* create a routing cache entry */
2154 	return __mkroute_input(skb, res, in_dev, daddr, saddr, tos);
2155 }
2156 
2157 /* Implements all the saddr-related checks as ip_route_input_slow(),
2158  * assuming daddr is valid and the destination is not a local broadcast one.
2159  * Uses the provided hint instead of performing a route lookup.
2160  */
2161 int ip_route_use_hint(struct sk_buff *skb, __be32 daddr, __be32 saddr,
2162 		      u8 tos, struct net_device *dev,
2163 		      const struct sk_buff *hint)
2164 {
2165 	struct in_device *in_dev = __in_dev_get_rcu(dev);
2166 	struct rtable *rt = skb_rtable(hint);
2167 	struct net *net = dev_net(dev);
2168 	int err = -EINVAL;
2169 	u32 tag = 0;
2170 
2171 	if (ipv4_is_multicast(saddr) || ipv4_is_lbcast(saddr))
2172 		goto martian_source;
2173 
2174 	if (ipv4_is_zeronet(saddr))
2175 		goto martian_source;
2176 
2177 	if (ipv4_is_loopback(saddr) && !IN_DEV_NET_ROUTE_LOCALNET(in_dev, net))
2178 		goto martian_source;
2179 
2180 	if (rt->rt_type != RTN_LOCAL)
2181 		goto skip_validate_source;
2182 
2183 	tos &= IPTOS_RT_MASK;
2184 	err = fib_validate_source(skb, saddr, daddr, tos, 0, dev, in_dev, &tag);
2185 	if (err < 0)
2186 		goto martian_source;
2187 
2188 skip_validate_source:
2189 	skb_dst_copy(skb, hint);
2190 	return 0;
2191 
2192 martian_source:
2193 	ip_handle_martian_source(dev, in_dev, skb, daddr, saddr);
2194 	return err;
2195 }
2196 
2197 /* get device for dst_alloc with local routes */
2198 static struct net_device *ip_rt_get_dev(struct net *net,
2199 					const struct fib_result *res)
2200 {
2201 	struct fib_nh_common *nhc = res->fi ? res->nhc : NULL;
2202 	struct net_device *dev = NULL;
2203 
2204 	if (nhc)
2205 		dev = l3mdev_master_dev_rcu(nhc->nhc_dev);
2206 
2207 	return dev ? : net->loopback_dev;
2208 }
2209 
2210 /*
2211  *	NOTE. We drop all the packets that has local source
2212  *	addresses, because every properly looped back packet
2213  *	must have correct destination already attached by output routine.
2214  *	Changes in the enforced policies must be applied also to
2215  *	ip_route_use_hint().
2216  *
2217  *	Such approach solves two big problems:
2218  *	1. Not simplex devices are handled properly.
2219  *	2. IP spoofing attempts are filtered with 100% of guarantee.
2220  *	called with rcu_read_lock()
2221  */
2222 
2223 static int ip_route_input_slow(struct sk_buff *skb, __be32 daddr, __be32 saddr,
2224 			       u8 tos, struct net_device *dev,
2225 			       struct fib_result *res)
2226 {
2227 	struct in_device *in_dev = __in_dev_get_rcu(dev);
2228 	struct flow_keys *flkeys = NULL, _flkeys;
2229 	struct net    *net = dev_net(dev);
2230 	struct ip_tunnel_info *tun_info;
2231 	int		err = -EINVAL;
2232 	unsigned int	flags = 0;
2233 	u32		itag = 0;
2234 	struct rtable	*rth;
2235 	struct flowi4	fl4;
2236 	bool do_cache = true;
2237 
2238 	/* IP on this device is disabled. */
2239 
2240 	if (!in_dev)
2241 		goto out;
2242 
2243 	/* Check for the most weird martians, which can be not detected
2244 	 * by fib_lookup.
2245 	 */
2246 
2247 	tun_info = skb_tunnel_info(skb);
2248 	if (tun_info && !(tun_info->mode & IP_TUNNEL_INFO_TX))
2249 		fl4.flowi4_tun_key.tun_id = tun_info->key.tun_id;
2250 	else
2251 		fl4.flowi4_tun_key.tun_id = 0;
2252 	skb_dst_drop(skb);
2253 
2254 	if (ipv4_is_multicast(saddr) || ipv4_is_lbcast(saddr))
2255 		goto martian_source;
2256 
2257 	res->fi = NULL;
2258 	res->table = NULL;
2259 	if (ipv4_is_lbcast(daddr) || (saddr == 0 && daddr == 0))
2260 		goto brd_input;
2261 
2262 	/* Accept zero addresses only to limited broadcast;
2263 	 * I even do not know to fix it or not. Waiting for complains :-)
2264 	 */
2265 	if (ipv4_is_zeronet(saddr))
2266 		goto martian_source;
2267 
2268 	if (ipv4_is_zeronet(daddr))
2269 		goto martian_destination;
2270 
2271 	/* Following code try to avoid calling IN_DEV_NET_ROUTE_LOCALNET(),
2272 	 * and call it once if daddr or/and saddr are loopback addresses
2273 	 */
2274 	if (ipv4_is_loopback(daddr)) {
2275 		if (!IN_DEV_NET_ROUTE_LOCALNET(in_dev, net))
2276 			goto martian_destination;
2277 	} else if (ipv4_is_loopback(saddr)) {
2278 		if (!IN_DEV_NET_ROUTE_LOCALNET(in_dev, net))
2279 			goto martian_source;
2280 	}
2281 
2282 	/*
2283 	 *	Now we are ready to route packet.
2284 	 */
2285 	fl4.flowi4_l3mdev = 0;
2286 	fl4.flowi4_oif = 0;
2287 	fl4.flowi4_iif = dev->ifindex;
2288 	fl4.flowi4_mark = skb->mark;
2289 	fl4.flowi4_tos = tos;
2290 	fl4.flowi4_scope = RT_SCOPE_UNIVERSE;
2291 	fl4.flowi4_flags = 0;
2292 	fl4.daddr = daddr;
2293 	fl4.saddr = saddr;
2294 	fl4.flowi4_uid = sock_net_uid(net, NULL);
2295 	fl4.flowi4_multipath_hash = 0;
2296 
2297 	if (fib4_rules_early_flow_dissect(net, skb, &fl4, &_flkeys)) {
2298 		flkeys = &_flkeys;
2299 	} else {
2300 		fl4.flowi4_proto = 0;
2301 		fl4.fl4_sport = 0;
2302 		fl4.fl4_dport = 0;
2303 	}
2304 
2305 	err = fib_lookup(net, &fl4, res, 0);
2306 	if (err != 0) {
2307 		if (!IN_DEV_FORWARD(in_dev))
2308 			err = -EHOSTUNREACH;
2309 		goto no_route;
2310 	}
2311 
2312 	if (res->type == RTN_BROADCAST) {
2313 		if (IN_DEV_BFORWARD(in_dev))
2314 			goto make_route;
2315 		/* not do cache if bc_forwarding is enabled */
2316 		if (IPV4_DEVCONF_ALL(net, BC_FORWARDING))
2317 			do_cache = false;
2318 		goto brd_input;
2319 	}
2320 
2321 	if (res->type == RTN_LOCAL) {
2322 		err = fib_validate_source(skb, saddr, daddr, tos,
2323 					  0, dev, in_dev, &itag);
2324 		if (err < 0)
2325 			goto martian_source;
2326 		goto local_input;
2327 	}
2328 
2329 	if (!IN_DEV_FORWARD(in_dev)) {
2330 		err = -EHOSTUNREACH;
2331 		goto no_route;
2332 	}
2333 	if (res->type != RTN_UNICAST)
2334 		goto martian_destination;
2335 
2336 make_route:
2337 	err = ip_mkroute_input(skb, res, in_dev, daddr, saddr, tos, flkeys);
2338 out:	return err;
2339 
2340 brd_input:
2341 	if (skb->protocol != htons(ETH_P_IP))
2342 		goto e_inval;
2343 
2344 	if (!ipv4_is_zeronet(saddr)) {
2345 		err = fib_validate_source(skb, saddr, 0, tos, 0, dev,
2346 					  in_dev, &itag);
2347 		if (err < 0)
2348 			goto martian_source;
2349 	}
2350 	flags |= RTCF_BROADCAST;
2351 	res->type = RTN_BROADCAST;
2352 	RT_CACHE_STAT_INC(in_brd);
2353 
2354 local_input:
2355 	if (IN_DEV_ORCONF(in_dev, NOPOLICY))
2356 		IPCB(skb)->flags |= IPSKB_NOPOLICY;
2357 
2358 	do_cache &= res->fi && !itag;
2359 	if (do_cache) {
2360 		struct fib_nh_common *nhc = FIB_RES_NHC(*res);
2361 
2362 		rth = rcu_dereference(nhc->nhc_rth_input);
2363 		if (rt_cache_valid(rth)) {
2364 			skb_dst_set_noref(skb, &rth->dst);
2365 			err = 0;
2366 			goto out;
2367 		}
2368 	}
2369 
2370 	rth = rt_dst_alloc(ip_rt_get_dev(net, res),
2371 			   flags | RTCF_LOCAL, res->type, false);
2372 	if (!rth)
2373 		goto e_nobufs;
2374 
2375 	rth->dst.output= ip_rt_bug;
2376 #ifdef CONFIG_IP_ROUTE_CLASSID
2377 	rth->dst.tclassid = itag;
2378 #endif
2379 	rth->rt_is_input = 1;
2380 
2381 	RT_CACHE_STAT_INC(in_slow_tot);
2382 	if (res->type == RTN_UNREACHABLE) {
2383 		rth->dst.input= ip_error;
2384 		rth->dst.error= -err;
2385 		rth->rt_flags	&= ~RTCF_LOCAL;
2386 	}
2387 
2388 	if (do_cache) {
2389 		struct fib_nh_common *nhc = FIB_RES_NHC(*res);
2390 
2391 		rth->dst.lwtstate = lwtstate_get(nhc->nhc_lwtstate);
2392 		if (lwtunnel_input_redirect(rth->dst.lwtstate)) {
2393 			WARN_ON(rth->dst.input == lwtunnel_input);
2394 			rth->dst.lwtstate->orig_input = rth->dst.input;
2395 			rth->dst.input = lwtunnel_input;
2396 		}
2397 
2398 		if (unlikely(!rt_cache_route(nhc, rth)))
2399 			rt_add_uncached_list(rth);
2400 	}
2401 	skb_dst_set(skb, &rth->dst);
2402 	err = 0;
2403 	goto out;
2404 
2405 no_route:
2406 	RT_CACHE_STAT_INC(in_no_route);
2407 	res->type = RTN_UNREACHABLE;
2408 	res->fi = NULL;
2409 	res->table = NULL;
2410 	goto local_input;
2411 
2412 	/*
2413 	 *	Do not cache martian addresses: they should be logged (RFC1812)
2414 	 */
2415 martian_destination:
2416 	RT_CACHE_STAT_INC(in_martian_dst);
2417 #ifdef CONFIG_IP_ROUTE_VERBOSE
2418 	if (IN_DEV_LOG_MARTIANS(in_dev))
2419 		net_warn_ratelimited("martian destination %pI4 from %pI4, dev %s\n",
2420 				     &daddr, &saddr, dev->name);
2421 #endif
2422 
2423 e_inval:
2424 	err = -EINVAL;
2425 	goto out;
2426 
2427 e_nobufs:
2428 	err = -ENOBUFS;
2429 	goto out;
2430 
2431 martian_source:
2432 	ip_handle_martian_source(dev, in_dev, skb, daddr, saddr);
2433 	goto out;
2434 }
2435 
2436 /* called with rcu_read_lock held */
2437 static int ip_route_input_rcu(struct sk_buff *skb, __be32 daddr, __be32 saddr,
2438 			      u8 tos, struct net_device *dev, struct fib_result *res)
2439 {
2440 	/* Multicast recognition logic is moved from route cache to here.
2441 	 * The problem was that too many Ethernet cards have broken/missing
2442 	 * hardware multicast filters :-( As result the host on multicasting
2443 	 * network acquires a lot of useless route cache entries, sort of
2444 	 * SDR messages from all the world. Now we try to get rid of them.
2445 	 * Really, provided software IP multicast filter is organized
2446 	 * reasonably (at least, hashed), it does not result in a slowdown
2447 	 * comparing with route cache reject entries.
2448 	 * Note, that multicast routers are not affected, because
2449 	 * route cache entry is created eventually.
2450 	 */
2451 	if (ipv4_is_multicast(daddr)) {
2452 		struct in_device *in_dev = __in_dev_get_rcu(dev);
2453 		int our = 0;
2454 		int err = -EINVAL;
2455 
2456 		if (!in_dev)
2457 			return err;
2458 		our = ip_check_mc_rcu(in_dev, daddr, saddr,
2459 				      ip_hdr(skb)->protocol);
2460 
2461 		/* check l3 master if no match yet */
2462 		if (!our && netif_is_l3_slave(dev)) {
2463 			struct in_device *l3_in_dev;
2464 
2465 			l3_in_dev = __in_dev_get_rcu(skb->dev);
2466 			if (l3_in_dev)
2467 				our = ip_check_mc_rcu(l3_in_dev, daddr, saddr,
2468 						      ip_hdr(skb)->protocol);
2469 		}
2470 
2471 		if (our
2472 #ifdef CONFIG_IP_MROUTE
2473 			||
2474 		    (!ipv4_is_local_multicast(daddr) &&
2475 		     IN_DEV_MFORWARD(in_dev))
2476 #endif
2477 		   ) {
2478 			err = ip_route_input_mc(skb, daddr, saddr,
2479 						tos, dev, our);
2480 		}
2481 		return err;
2482 	}
2483 
2484 	return ip_route_input_slow(skb, daddr, saddr, tos, dev, res);
2485 }
2486 
2487 int ip_route_input_noref(struct sk_buff *skb, __be32 daddr, __be32 saddr,
2488 			 u8 tos, struct net_device *dev)
2489 {
2490 	struct fib_result res;
2491 	int err;
2492 
2493 	tos &= IPTOS_RT_MASK;
2494 	rcu_read_lock();
2495 	err = ip_route_input_rcu(skb, daddr, saddr, tos, dev, &res);
2496 	rcu_read_unlock();
2497 
2498 	return err;
2499 }
2500 EXPORT_SYMBOL(ip_route_input_noref);
2501 
2502 /* called with rcu_read_lock() */
2503 static struct rtable *__mkroute_output(const struct fib_result *res,
2504 				       const struct flowi4 *fl4, int orig_oif,
2505 				       struct net_device *dev_out,
2506 				       unsigned int flags)
2507 {
2508 	struct fib_info *fi = res->fi;
2509 	struct fib_nh_exception *fnhe;
2510 	struct in_device *in_dev;
2511 	u16 type = res->type;
2512 	struct rtable *rth;
2513 	bool do_cache;
2514 
2515 	in_dev = __in_dev_get_rcu(dev_out);
2516 	if (!in_dev)
2517 		return ERR_PTR(-EINVAL);
2518 
2519 	if (likely(!IN_DEV_ROUTE_LOCALNET(in_dev)))
2520 		if (ipv4_is_loopback(fl4->saddr) &&
2521 		    !(dev_out->flags & IFF_LOOPBACK) &&
2522 		    !netif_is_l3_master(dev_out))
2523 			return ERR_PTR(-EINVAL);
2524 
2525 	if (ipv4_is_lbcast(fl4->daddr))
2526 		type = RTN_BROADCAST;
2527 	else if (ipv4_is_multicast(fl4->daddr))
2528 		type = RTN_MULTICAST;
2529 	else if (ipv4_is_zeronet(fl4->daddr))
2530 		return ERR_PTR(-EINVAL);
2531 
2532 	if (dev_out->flags & IFF_LOOPBACK)
2533 		flags |= RTCF_LOCAL;
2534 
2535 	do_cache = true;
2536 	if (type == RTN_BROADCAST) {
2537 		flags |= RTCF_BROADCAST | RTCF_LOCAL;
2538 		fi = NULL;
2539 	} else if (type == RTN_MULTICAST) {
2540 		flags |= RTCF_MULTICAST | RTCF_LOCAL;
2541 		if (!ip_check_mc_rcu(in_dev, fl4->daddr, fl4->saddr,
2542 				     fl4->flowi4_proto))
2543 			flags &= ~RTCF_LOCAL;
2544 		else
2545 			do_cache = false;
2546 		/* If multicast route do not exist use
2547 		 * default one, but do not gateway in this case.
2548 		 * Yes, it is hack.
2549 		 */
2550 		if (fi && res->prefixlen < 4)
2551 			fi = NULL;
2552 	} else if ((type == RTN_LOCAL) && (orig_oif != 0) &&
2553 		   (orig_oif != dev_out->ifindex)) {
2554 		/* For local routes that require a particular output interface
2555 		 * we do not want to cache the result.  Caching the result
2556 		 * causes incorrect behaviour when there are multiple source
2557 		 * addresses on the interface, the end result being that if the
2558 		 * intended recipient is waiting on that interface for the
2559 		 * packet he won't receive it because it will be delivered on
2560 		 * the loopback interface and the IP_PKTINFO ipi_ifindex will
2561 		 * be set to the loopback interface as well.
2562 		 */
2563 		do_cache = false;
2564 	}
2565 
2566 	fnhe = NULL;
2567 	do_cache &= fi != NULL;
2568 	if (fi) {
2569 		struct fib_nh_common *nhc = FIB_RES_NHC(*res);
2570 		struct rtable __rcu **prth;
2571 
2572 		fnhe = find_exception(nhc, fl4->daddr);
2573 		if (!do_cache)
2574 			goto add;
2575 		if (fnhe) {
2576 			prth = &fnhe->fnhe_rth_output;
2577 		} else {
2578 			if (unlikely(fl4->flowi4_flags &
2579 				     FLOWI_FLAG_KNOWN_NH &&
2580 				     !(nhc->nhc_gw_family &&
2581 				       nhc->nhc_scope == RT_SCOPE_LINK))) {
2582 				do_cache = false;
2583 				goto add;
2584 			}
2585 			prth = raw_cpu_ptr(nhc->nhc_pcpu_rth_output);
2586 		}
2587 		rth = rcu_dereference(*prth);
2588 		if (rt_cache_valid(rth) && dst_hold_safe(&rth->dst))
2589 			return rth;
2590 	}
2591 
2592 add:
2593 	rth = rt_dst_alloc(dev_out, flags, type,
2594 			   IN_DEV_ORCONF(in_dev, NOXFRM));
2595 	if (!rth)
2596 		return ERR_PTR(-ENOBUFS);
2597 
2598 	rth->rt_iif = orig_oif;
2599 
2600 	RT_CACHE_STAT_INC(out_slow_tot);
2601 
2602 	if (flags & (RTCF_BROADCAST | RTCF_MULTICAST)) {
2603 		if (flags & RTCF_LOCAL &&
2604 		    !(dev_out->flags & IFF_LOOPBACK)) {
2605 			rth->dst.output = ip_mc_output;
2606 			RT_CACHE_STAT_INC(out_slow_mc);
2607 		}
2608 #ifdef CONFIG_IP_MROUTE
2609 		if (type == RTN_MULTICAST) {
2610 			if (IN_DEV_MFORWARD(in_dev) &&
2611 			    !ipv4_is_local_multicast(fl4->daddr)) {
2612 				rth->dst.input = ip_mr_input;
2613 				rth->dst.output = ip_mc_output;
2614 			}
2615 		}
2616 #endif
2617 	}
2618 
2619 	rt_set_nexthop(rth, fl4->daddr, res, fnhe, fi, type, 0, do_cache);
2620 	lwtunnel_set_redirect(&rth->dst);
2621 
2622 	return rth;
2623 }
2624 
2625 /*
2626  * Major route resolver routine.
2627  */
2628 
2629 struct rtable *ip_route_output_key_hash(struct net *net, struct flowi4 *fl4,
2630 					const struct sk_buff *skb)
2631 {
2632 	struct fib_result res = {
2633 		.type		= RTN_UNSPEC,
2634 		.fi		= NULL,
2635 		.table		= NULL,
2636 		.tclassid	= 0,
2637 	};
2638 	struct rtable *rth;
2639 
2640 	fl4->flowi4_iif = LOOPBACK_IFINDEX;
2641 	ip_rt_fix_tos(fl4);
2642 
2643 	rcu_read_lock();
2644 	rth = ip_route_output_key_hash_rcu(net, fl4, &res, skb);
2645 	rcu_read_unlock();
2646 
2647 	return rth;
2648 }
2649 EXPORT_SYMBOL_GPL(ip_route_output_key_hash);
2650 
2651 struct rtable *ip_route_output_key_hash_rcu(struct net *net, struct flowi4 *fl4,
2652 					    struct fib_result *res,
2653 					    const struct sk_buff *skb)
2654 {
2655 	struct net_device *dev_out = NULL;
2656 	int orig_oif = fl4->flowi4_oif;
2657 	unsigned int flags = 0;
2658 	struct rtable *rth;
2659 	int err;
2660 
2661 	if (fl4->saddr) {
2662 		if (ipv4_is_multicast(fl4->saddr) ||
2663 		    ipv4_is_lbcast(fl4->saddr) ||
2664 		    ipv4_is_zeronet(fl4->saddr)) {
2665 			rth = ERR_PTR(-EINVAL);
2666 			goto out;
2667 		}
2668 
2669 		rth = ERR_PTR(-ENETUNREACH);
2670 
2671 		/* I removed check for oif == dev_out->oif here.
2672 		 * It was wrong for two reasons:
2673 		 * 1. ip_dev_find(net, saddr) can return wrong iface, if saddr
2674 		 *    is assigned to multiple interfaces.
2675 		 * 2. Moreover, we are allowed to send packets with saddr
2676 		 *    of another iface. --ANK
2677 		 */
2678 
2679 		if (fl4->flowi4_oif == 0 &&
2680 		    (ipv4_is_multicast(fl4->daddr) ||
2681 		     ipv4_is_lbcast(fl4->daddr))) {
2682 			/* It is equivalent to inet_addr_type(saddr) == RTN_LOCAL */
2683 			dev_out = __ip_dev_find(net, fl4->saddr, false);
2684 			if (!dev_out)
2685 				goto out;
2686 
2687 			/* Special hack: user can direct multicasts
2688 			 * and limited broadcast via necessary interface
2689 			 * without fiddling with IP_MULTICAST_IF or IP_PKTINFO.
2690 			 * This hack is not just for fun, it allows
2691 			 * vic,vat and friends to work.
2692 			 * They bind socket to loopback, set ttl to zero
2693 			 * and expect that it will work.
2694 			 * From the viewpoint of routing cache they are broken,
2695 			 * because we are not allowed to build multicast path
2696 			 * with loopback source addr (look, routing cache
2697 			 * cannot know, that ttl is zero, so that packet
2698 			 * will not leave this host and route is valid).
2699 			 * Luckily, this hack is good workaround.
2700 			 */
2701 
2702 			fl4->flowi4_oif = dev_out->ifindex;
2703 			goto make_route;
2704 		}
2705 
2706 		if (!(fl4->flowi4_flags & FLOWI_FLAG_ANYSRC)) {
2707 			/* It is equivalent to inet_addr_type(saddr) == RTN_LOCAL */
2708 			if (!__ip_dev_find(net, fl4->saddr, false))
2709 				goto out;
2710 		}
2711 	}
2712 
2713 
2714 	if (fl4->flowi4_oif) {
2715 		dev_out = dev_get_by_index_rcu(net, fl4->flowi4_oif);
2716 		rth = ERR_PTR(-ENODEV);
2717 		if (!dev_out)
2718 			goto out;
2719 
2720 		/* RACE: Check return value of inet_select_addr instead. */
2721 		if (!(dev_out->flags & IFF_UP) || !__in_dev_get_rcu(dev_out)) {
2722 			rth = ERR_PTR(-ENETUNREACH);
2723 			goto out;
2724 		}
2725 		if (ipv4_is_local_multicast(fl4->daddr) ||
2726 		    ipv4_is_lbcast(fl4->daddr) ||
2727 		    fl4->flowi4_proto == IPPROTO_IGMP) {
2728 			if (!fl4->saddr)
2729 				fl4->saddr = inet_select_addr(dev_out, 0,
2730 							      RT_SCOPE_LINK);
2731 			goto make_route;
2732 		}
2733 		if (!fl4->saddr) {
2734 			if (ipv4_is_multicast(fl4->daddr))
2735 				fl4->saddr = inet_select_addr(dev_out, 0,
2736 							      fl4->flowi4_scope);
2737 			else if (!fl4->daddr)
2738 				fl4->saddr = inet_select_addr(dev_out, 0,
2739 							      RT_SCOPE_HOST);
2740 		}
2741 	}
2742 
2743 	if (!fl4->daddr) {
2744 		fl4->daddr = fl4->saddr;
2745 		if (!fl4->daddr)
2746 			fl4->daddr = fl4->saddr = htonl(INADDR_LOOPBACK);
2747 		dev_out = net->loopback_dev;
2748 		fl4->flowi4_oif = LOOPBACK_IFINDEX;
2749 		res->type = RTN_LOCAL;
2750 		flags |= RTCF_LOCAL;
2751 		goto make_route;
2752 	}
2753 
2754 	err = fib_lookup(net, fl4, res, 0);
2755 	if (err) {
2756 		res->fi = NULL;
2757 		res->table = NULL;
2758 		if (fl4->flowi4_oif &&
2759 		    (ipv4_is_multicast(fl4->daddr) || !fl4->flowi4_l3mdev)) {
2760 			/* Apparently, routing tables are wrong. Assume,
2761 			 * that the destination is on link.
2762 			 *
2763 			 * WHY? DW.
2764 			 * Because we are allowed to send to iface
2765 			 * even if it has NO routes and NO assigned
2766 			 * addresses. When oif is specified, routing
2767 			 * tables are looked up with only one purpose:
2768 			 * to catch if destination is gatewayed, rather than
2769 			 * direct. Moreover, if MSG_DONTROUTE is set,
2770 			 * we send packet, ignoring both routing tables
2771 			 * and ifaddr state. --ANK
2772 			 *
2773 			 *
2774 			 * We could make it even if oif is unknown,
2775 			 * likely IPv6, but we do not.
2776 			 */
2777 
2778 			if (fl4->saddr == 0)
2779 				fl4->saddr = inet_select_addr(dev_out, 0,
2780 							      RT_SCOPE_LINK);
2781 			res->type = RTN_UNICAST;
2782 			goto make_route;
2783 		}
2784 		rth = ERR_PTR(err);
2785 		goto out;
2786 	}
2787 
2788 	if (res->type == RTN_LOCAL) {
2789 		if (!fl4->saddr) {
2790 			if (res->fi->fib_prefsrc)
2791 				fl4->saddr = res->fi->fib_prefsrc;
2792 			else
2793 				fl4->saddr = fl4->daddr;
2794 		}
2795 
2796 		/* L3 master device is the loopback for that domain */
2797 		dev_out = l3mdev_master_dev_rcu(FIB_RES_DEV(*res)) ? :
2798 			net->loopback_dev;
2799 
2800 		/* make sure orig_oif points to fib result device even
2801 		 * though packet rx/tx happens over loopback or l3mdev
2802 		 */
2803 		orig_oif = FIB_RES_OIF(*res);
2804 
2805 		fl4->flowi4_oif = dev_out->ifindex;
2806 		flags |= RTCF_LOCAL;
2807 		goto make_route;
2808 	}
2809 
2810 	fib_select_path(net, res, fl4, skb);
2811 
2812 	dev_out = FIB_RES_DEV(*res);
2813 
2814 make_route:
2815 	rth = __mkroute_output(res, fl4, orig_oif, dev_out, flags);
2816 
2817 out:
2818 	return rth;
2819 }
2820 
2821 static struct dst_ops ipv4_dst_blackhole_ops = {
2822 	.family			= AF_INET,
2823 	.default_advmss		= ipv4_default_advmss,
2824 	.neigh_lookup		= ipv4_neigh_lookup,
2825 	.check			= dst_blackhole_check,
2826 	.cow_metrics		= dst_blackhole_cow_metrics,
2827 	.update_pmtu		= dst_blackhole_update_pmtu,
2828 	.redirect		= dst_blackhole_redirect,
2829 	.mtu			= dst_blackhole_mtu,
2830 };
2831 
2832 struct dst_entry *ipv4_blackhole_route(struct net *net, struct dst_entry *dst_orig)
2833 {
2834 	struct rtable *ort = (struct rtable *) dst_orig;
2835 	struct rtable *rt;
2836 
2837 	rt = dst_alloc(&ipv4_dst_blackhole_ops, NULL, DST_OBSOLETE_DEAD, 0);
2838 	if (rt) {
2839 		struct dst_entry *new = &rt->dst;
2840 
2841 		new->__use = 1;
2842 		new->input = dst_discard;
2843 		new->output = dst_discard_out;
2844 
2845 		new->dev = net->loopback_dev;
2846 		netdev_hold(new->dev, &new->dev_tracker, GFP_ATOMIC);
2847 
2848 		rt->rt_is_input = ort->rt_is_input;
2849 		rt->rt_iif = ort->rt_iif;
2850 		rt->rt_pmtu = ort->rt_pmtu;
2851 		rt->rt_mtu_locked = ort->rt_mtu_locked;
2852 
2853 		rt->rt_genid = rt_genid_ipv4(net);
2854 		rt->rt_flags = ort->rt_flags;
2855 		rt->rt_type = ort->rt_type;
2856 		rt->rt_uses_gateway = ort->rt_uses_gateway;
2857 		rt->rt_gw_family = ort->rt_gw_family;
2858 		if (rt->rt_gw_family == AF_INET)
2859 			rt->rt_gw4 = ort->rt_gw4;
2860 		else if (rt->rt_gw_family == AF_INET6)
2861 			rt->rt_gw6 = ort->rt_gw6;
2862 	}
2863 
2864 	dst_release(dst_orig);
2865 
2866 	return rt ? &rt->dst : ERR_PTR(-ENOMEM);
2867 }
2868 
2869 struct rtable *ip_route_output_flow(struct net *net, struct flowi4 *flp4,
2870 				    const struct sock *sk)
2871 {
2872 	struct rtable *rt = __ip_route_output_key(net, flp4);
2873 
2874 	if (IS_ERR(rt))
2875 		return rt;
2876 
2877 	if (flp4->flowi4_proto) {
2878 		flp4->flowi4_oif = rt->dst.dev->ifindex;
2879 		rt = (struct rtable *)xfrm_lookup_route(net, &rt->dst,
2880 							flowi4_to_flowi(flp4),
2881 							sk, 0);
2882 	}
2883 
2884 	return rt;
2885 }
2886 EXPORT_SYMBOL_GPL(ip_route_output_flow);
2887 
2888 /* called with rcu_read_lock held */
2889 static int rt_fill_info(struct net *net, __be32 dst, __be32 src,
2890 			struct rtable *rt, u32 table_id, struct flowi4 *fl4,
2891 			struct sk_buff *skb, u32 portid, u32 seq,
2892 			unsigned int flags)
2893 {
2894 	struct rtmsg *r;
2895 	struct nlmsghdr *nlh;
2896 	unsigned long expires = 0;
2897 	u32 error;
2898 	u32 metrics[RTAX_MAX];
2899 
2900 	nlh = nlmsg_put(skb, portid, seq, RTM_NEWROUTE, sizeof(*r), flags);
2901 	if (!nlh)
2902 		return -EMSGSIZE;
2903 
2904 	r = nlmsg_data(nlh);
2905 	r->rtm_family	 = AF_INET;
2906 	r->rtm_dst_len	= 32;
2907 	r->rtm_src_len	= 0;
2908 	r->rtm_tos	= fl4 ? fl4->flowi4_tos : 0;
2909 	r->rtm_table	= table_id < 256 ? table_id : RT_TABLE_COMPAT;
2910 	if (nla_put_u32(skb, RTA_TABLE, table_id))
2911 		goto nla_put_failure;
2912 	r->rtm_type	= rt->rt_type;
2913 	r->rtm_scope	= RT_SCOPE_UNIVERSE;
2914 	r->rtm_protocol = RTPROT_UNSPEC;
2915 	r->rtm_flags	= (rt->rt_flags & ~0xFFFF) | RTM_F_CLONED;
2916 	if (rt->rt_flags & RTCF_NOTIFY)
2917 		r->rtm_flags |= RTM_F_NOTIFY;
2918 	if (IPCB(skb)->flags & IPSKB_DOREDIRECT)
2919 		r->rtm_flags |= RTCF_DOREDIRECT;
2920 
2921 	if (nla_put_in_addr(skb, RTA_DST, dst))
2922 		goto nla_put_failure;
2923 	if (src) {
2924 		r->rtm_src_len = 32;
2925 		if (nla_put_in_addr(skb, RTA_SRC, src))
2926 			goto nla_put_failure;
2927 	}
2928 	if (rt->dst.dev &&
2929 	    nla_put_u32(skb, RTA_OIF, rt->dst.dev->ifindex))
2930 		goto nla_put_failure;
2931 	if (rt->dst.lwtstate &&
2932 	    lwtunnel_fill_encap(skb, rt->dst.lwtstate, RTA_ENCAP, RTA_ENCAP_TYPE) < 0)
2933 		goto nla_put_failure;
2934 #ifdef CONFIG_IP_ROUTE_CLASSID
2935 	if (rt->dst.tclassid &&
2936 	    nla_put_u32(skb, RTA_FLOW, rt->dst.tclassid))
2937 		goto nla_put_failure;
2938 #endif
2939 	if (fl4 && !rt_is_input_route(rt) &&
2940 	    fl4->saddr != src) {
2941 		if (nla_put_in_addr(skb, RTA_PREFSRC, fl4->saddr))
2942 			goto nla_put_failure;
2943 	}
2944 	if (rt->rt_uses_gateway) {
2945 		if (rt->rt_gw_family == AF_INET &&
2946 		    nla_put_in_addr(skb, RTA_GATEWAY, rt->rt_gw4)) {
2947 			goto nla_put_failure;
2948 		} else if (rt->rt_gw_family == AF_INET6) {
2949 			int alen = sizeof(struct in6_addr);
2950 			struct nlattr *nla;
2951 			struct rtvia *via;
2952 
2953 			nla = nla_reserve(skb, RTA_VIA, alen + 2);
2954 			if (!nla)
2955 				goto nla_put_failure;
2956 
2957 			via = nla_data(nla);
2958 			via->rtvia_family = AF_INET6;
2959 			memcpy(via->rtvia_addr, &rt->rt_gw6, alen);
2960 		}
2961 	}
2962 
2963 	expires = rt->dst.expires;
2964 	if (expires) {
2965 		unsigned long now = jiffies;
2966 
2967 		if (time_before(now, expires))
2968 			expires -= now;
2969 		else
2970 			expires = 0;
2971 	}
2972 
2973 	memcpy(metrics, dst_metrics_ptr(&rt->dst), sizeof(metrics));
2974 	if (rt->rt_pmtu && expires)
2975 		metrics[RTAX_MTU - 1] = rt->rt_pmtu;
2976 	if (rt->rt_mtu_locked && expires)
2977 		metrics[RTAX_LOCK - 1] |= BIT(RTAX_MTU);
2978 	if (rtnetlink_put_metrics(skb, metrics) < 0)
2979 		goto nla_put_failure;
2980 
2981 	if (fl4) {
2982 		if (fl4->flowi4_mark &&
2983 		    nla_put_u32(skb, RTA_MARK, fl4->flowi4_mark))
2984 			goto nla_put_failure;
2985 
2986 		if (!uid_eq(fl4->flowi4_uid, INVALID_UID) &&
2987 		    nla_put_u32(skb, RTA_UID,
2988 				from_kuid_munged(current_user_ns(),
2989 						 fl4->flowi4_uid)))
2990 			goto nla_put_failure;
2991 
2992 		if (rt_is_input_route(rt)) {
2993 #ifdef CONFIG_IP_MROUTE
2994 			if (ipv4_is_multicast(dst) &&
2995 			    !ipv4_is_local_multicast(dst) &&
2996 			    IPV4_DEVCONF_ALL(net, MC_FORWARDING)) {
2997 				int err = ipmr_get_route(net, skb,
2998 							 fl4->saddr, fl4->daddr,
2999 							 r, portid);
3000 
3001 				if (err <= 0) {
3002 					if (err == 0)
3003 						return 0;
3004 					goto nla_put_failure;
3005 				}
3006 			} else
3007 #endif
3008 				if (nla_put_u32(skb, RTA_IIF, fl4->flowi4_iif))
3009 					goto nla_put_failure;
3010 		}
3011 	}
3012 
3013 	error = rt->dst.error;
3014 
3015 	if (rtnl_put_cacheinfo(skb, &rt->dst, 0, expires, error) < 0)
3016 		goto nla_put_failure;
3017 
3018 	nlmsg_end(skb, nlh);
3019 	return 0;
3020 
3021 nla_put_failure:
3022 	nlmsg_cancel(skb, nlh);
3023 	return -EMSGSIZE;
3024 }
3025 
3026 static int fnhe_dump_bucket(struct net *net, struct sk_buff *skb,
3027 			    struct netlink_callback *cb, u32 table_id,
3028 			    struct fnhe_hash_bucket *bucket, int genid,
3029 			    int *fa_index, int fa_start, unsigned int flags)
3030 {
3031 	int i;
3032 
3033 	for (i = 0; i < FNHE_HASH_SIZE; i++) {
3034 		struct fib_nh_exception *fnhe;
3035 
3036 		for (fnhe = rcu_dereference(bucket[i].chain); fnhe;
3037 		     fnhe = rcu_dereference(fnhe->fnhe_next)) {
3038 			struct rtable *rt;
3039 			int err;
3040 
3041 			if (*fa_index < fa_start)
3042 				goto next;
3043 
3044 			if (fnhe->fnhe_genid != genid)
3045 				goto next;
3046 
3047 			if (fnhe->fnhe_expires &&
3048 			    time_after(jiffies, fnhe->fnhe_expires))
3049 				goto next;
3050 
3051 			rt = rcu_dereference(fnhe->fnhe_rth_input);
3052 			if (!rt)
3053 				rt = rcu_dereference(fnhe->fnhe_rth_output);
3054 			if (!rt)
3055 				goto next;
3056 
3057 			err = rt_fill_info(net, fnhe->fnhe_daddr, 0, rt,
3058 					   table_id, NULL, skb,
3059 					   NETLINK_CB(cb->skb).portid,
3060 					   cb->nlh->nlmsg_seq, flags);
3061 			if (err)
3062 				return err;
3063 next:
3064 			(*fa_index)++;
3065 		}
3066 	}
3067 
3068 	return 0;
3069 }
3070 
3071 int fib_dump_info_fnhe(struct sk_buff *skb, struct netlink_callback *cb,
3072 		       u32 table_id, struct fib_info *fi,
3073 		       int *fa_index, int fa_start, unsigned int flags)
3074 {
3075 	struct net *net = sock_net(cb->skb->sk);
3076 	int nhsel, genid = fnhe_genid(net);
3077 
3078 	for (nhsel = 0; nhsel < fib_info_num_path(fi); nhsel++) {
3079 		struct fib_nh_common *nhc = fib_info_nhc(fi, nhsel);
3080 		struct fnhe_hash_bucket *bucket;
3081 		int err;
3082 
3083 		if (nhc->nhc_flags & RTNH_F_DEAD)
3084 			continue;
3085 
3086 		rcu_read_lock();
3087 		bucket = rcu_dereference(nhc->nhc_exceptions);
3088 		err = 0;
3089 		if (bucket)
3090 			err = fnhe_dump_bucket(net, skb, cb, table_id, bucket,
3091 					       genid, fa_index, fa_start,
3092 					       flags);
3093 		rcu_read_unlock();
3094 		if (err)
3095 			return err;
3096 	}
3097 
3098 	return 0;
3099 }
3100 
3101 static struct sk_buff *inet_rtm_getroute_build_skb(__be32 src, __be32 dst,
3102 						   u8 ip_proto, __be16 sport,
3103 						   __be16 dport)
3104 {
3105 	struct sk_buff *skb;
3106 	struct iphdr *iph;
3107 
3108 	skb = alloc_skb(NLMSG_GOODSIZE, GFP_KERNEL);
3109 	if (!skb)
3110 		return NULL;
3111 
3112 	/* Reserve room for dummy headers, this skb can pass
3113 	 * through good chunk of routing engine.
3114 	 */
3115 	skb_reset_mac_header(skb);
3116 	skb_reset_network_header(skb);
3117 	skb->protocol = htons(ETH_P_IP);
3118 	iph = skb_put(skb, sizeof(struct iphdr));
3119 	iph->protocol = ip_proto;
3120 	iph->saddr = src;
3121 	iph->daddr = dst;
3122 	iph->version = 0x4;
3123 	iph->frag_off = 0;
3124 	iph->ihl = 0x5;
3125 	skb_set_transport_header(skb, skb->len);
3126 
3127 	switch (iph->protocol) {
3128 	case IPPROTO_UDP: {
3129 		struct udphdr *udph;
3130 
3131 		udph = skb_put_zero(skb, sizeof(struct udphdr));
3132 		udph->source = sport;
3133 		udph->dest = dport;
3134 		udph->len = htons(sizeof(struct udphdr));
3135 		udph->check = 0;
3136 		break;
3137 	}
3138 	case IPPROTO_TCP: {
3139 		struct tcphdr *tcph;
3140 
3141 		tcph = skb_put_zero(skb, sizeof(struct tcphdr));
3142 		tcph->source	= sport;
3143 		tcph->dest	= dport;
3144 		tcph->doff	= sizeof(struct tcphdr) / 4;
3145 		tcph->rst = 1;
3146 		tcph->check = ~tcp_v4_check(sizeof(struct tcphdr),
3147 					    src, dst, 0);
3148 		break;
3149 	}
3150 	case IPPROTO_ICMP: {
3151 		struct icmphdr *icmph;
3152 
3153 		icmph = skb_put_zero(skb, sizeof(struct icmphdr));
3154 		icmph->type = ICMP_ECHO;
3155 		icmph->code = 0;
3156 	}
3157 	}
3158 
3159 	return skb;
3160 }
3161 
3162 static int inet_rtm_valid_getroute_req(struct sk_buff *skb,
3163 				       const struct nlmsghdr *nlh,
3164 				       struct nlattr **tb,
3165 				       struct netlink_ext_ack *extack)
3166 {
3167 	struct rtmsg *rtm;
3168 	int i, err;
3169 
3170 	if (nlh->nlmsg_len < nlmsg_msg_size(sizeof(*rtm))) {
3171 		NL_SET_ERR_MSG(extack,
3172 			       "ipv4: Invalid header for route get request");
3173 		return -EINVAL;
3174 	}
3175 
3176 	if (!netlink_strict_get_check(skb))
3177 		return nlmsg_parse_deprecated(nlh, sizeof(*rtm), tb, RTA_MAX,
3178 					      rtm_ipv4_policy, extack);
3179 
3180 	rtm = nlmsg_data(nlh);
3181 	if ((rtm->rtm_src_len && rtm->rtm_src_len != 32) ||
3182 	    (rtm->rtm_dst_len && rtm->rtm_dst_len != 32) ||
3183 	    rtm->rtm_table || rtm->rtm_protocol ||
3184 	    rtm->rtm_scope || rtm->rtm_type) {
3185 		NL_SET_ERR_MSG(extack, "ipv4: Invalid values in header for route get request");
3186 		return -EINVAL;
3187 	}
3188 
3189 	if (rtm->rtm_flags & ~(RTM_F_NOTIFY |
3190 			       RTM_F_LOOKUP_TABLE |
3191 			       RTM_F_FIB_MATCH)) {
3192 		NL_SET_ERR_MSG(extack, "ipv4: Unsupported rtm_flags for route get request");
3193 		return -EINVAL;
3194 	}
3195 
3196 	err = nlmsg_parse_deprecated_strict(nlh, sizeof(*rtm), tb, RTA_MAX,
3197 					    rtm_ipv4_policy, extack);
3198 	if (err)
3199 		return err;
3200 
3201 	if ((tb[RTA_SRC] && !rtm->rtm_src_len) ||
3202 	    (tb[RTA_DST] && !rtm->rtm_dst_len)) {
3203 		NL_SET_ERR_MSG(extack, "ipv4: rtm_src_len and rtm_dst_len must be 32 for IPv4");
3204 		return -EINVAL;
3205 	}
3206 
3207 	for (i = 0; i <= RTA_MAX; i++) {
3208 		if (!tb[i])
3209 			continue;
3210 
3211 		switch (i) {
3212 		case RTA_IIF:
3213 		case RTA_OIF:
3214 		case RTA_SRC:
3215 		case RTA_DST:
3216 		case RTA_IP_PROTO:
3217 		case RTA_SPORT:
3218 		case RTA_DPORT:
3219 		case RTA_MARK:
3220 		case RTA_UID:
3221 			break;
3222 		default:
3223 			NL_SET_ERR_MSG(extack, "ipv4: Unsupported attribute in route get request");
3224 			return -EINVAL;
3225 		}
3226 	}
3227 
3228 	return 0;
3229 }
3230 
3231 static int inet_rtm_getroute(struct sk_buff *in_skb, struct nlmsghdr *nlh,
3232 			     struct netlink_ext_ack *extack)
3233 {
3234 	struct net *net = sock_net(in_skb->sk);
3235 	struct nlattr *tb[RTA_MAX+1];
3236 	u32 table_id = RT_TABLE_MAIN;
3237 	__be16 sport = 0, dport = 0;
3238 	struct fib_result res = {};
3239 	u8 ip_proto = IPPROTO_UDP;
3240 	struct rtable *rt = NULL;
3241 	struct sk_buff *skb;
3242 	struct rtmsg *rtm;
3243 	struct flowi4 fl4 = {};
3244 	__be32 dst = 0;
3245 	__be32 src = 0;
3246 	kuid_t uid;
3247 	u32 iif;
3248 	int err;
3249 	int mark;
3250 
3251 	err = inet_rtm_valid_getroute_req(in_skb, nlh, tb, extack);
3252 	if (err < 0)
3253 		return err;
3254 
3255 	rtm = nlmsg_data(nlh);
3256 	src = tb[RTA_SRC] ? nla_get_in_addr(tb[RTA_SRC]) : 0;
3257 	dst = tb[RTA_DST] ? nla_get_in_addr(tb[RTA_DST]) : 0;
3258 	iif = tb[RTA_IIF] ? nla_get_u32(tb[RTA_IIF]) : 0;
3259 	mark = tb[RTA_MARK] ? nla_get_u32(tb[RTA_MARK]) : 0;
3260 	if (tb[RTA_UID])
3261 		uid = make_kuid(current_user_ns(), nla_get_u32(tb[RTA_UID]));
3262 	else
3263 		uid = (iif ? INVALID_UID : current_uid());
3264 
3265 	if (tb[RTA_IP_PROTO]) {
3266 		err = rtm_getroute_parse_ip_proto(tb[RTA_IP_PROTO],
3267 						  &ip_proto, AF_INET, extack);
3268 		if (err)
3269 			return err;
3270 	}
3271 
3272 	if (tb[RTA_SPORT])
3273 		sport = nla_get_be16(tb[RTA_SPORT]);
3274 
3275 	if (tb[RTA_DPORT])
3276 		dport = nla_get_be16(tb[RTA_DPORT]);
3277 
3278 	skb = inet_rtm_getroute_build_skb(src, dst, ip_proto, sport, dport);
3279 	if (!skb)
3280 		return -ENOBUFS;
3281 
3282 	fl4.daddr = dst;
3283 	fl4.saddr = src;
3284 	fl4.flowi4_tos = rtm->rtm_tos & IPTOS_RT_MASK;
3285 	fl4.flowi4_oif = tb[RTA_OIF] ? nla_get_u32(tb[RTA_OIF]) : 0;
3286 	fl4.flowi4_mark = mark;
3287 	fl4.flowi4_uid = uid;
3288 	if (sport)
3289 		fl4.fl4_sport = sport;
3290 	if (dport)
3291 		fl4.fl4_dport = dport;
3292 	fl4.flowi4_proto = ip_proto;
3293 
3294 	rcu_read_lock();
3295 
3296 	if (iif) {
3297 		struct net_device *dev;
3298 
3299 		dev = dev_get_by_index_rcu(net, iif);
3300 		if (!dev) {
3301 			err = -ENODEV;
3302 			goto errout_rcu;
3303 		}
3304 
3305 		fl4.flowi4_iif = iif; /* for rt_fill_info */
3306 		skb->dev	= dev;
3307 		skb->mark	= mark;
3308 		err = ip_route_input_rcu(skb, dst, src,
3309 					 rtm->rtm_tos & IPTOS_RT_MASK, dev,
3310 					 &res);
3311 
3312 		rt = skb_rtable(skb);
3313 		if (err == 0 && rt->dst.error)
3314 			err = -rt->dst.error;
3315 	} else {
3316 		fl4.flowi4_iif = LOOPBACK_IFINDEX;
3317 		skb->dev = net->loopback_dev;
3318 		rt = ip_route_output_key_hash_rcu(net, &fl4, &res, skb);
3319 		err = 0;
3320 		if (IS_ERR(rt))
3321 			err = PTR_ERR(rt);
3322 		else
3323 			skb_dst_set(skb, &rt->dst);
3324 	}
3325 
3326 	if (err)
3327 		goto errout_rcu;
3328 
3329 	if (rtm->rtm_flags & RTM_F_NOTIFY)
3330 		rt->rt_flags |= RTCF_NOTIFY;
3331 
3332 	if (rtm->rtm_flags & RTM_F_LOOKUP_TABLE)
3333 		table_id = res.table ? res.table->tb_id : 0;
3334 
3335 	/* reset skb for netlink reply msg */
3336 	skb_trim(skb, 0);
3337 	skb_reset_network_header(skb);
3338 	skb_reset_transport_header(skb);
3339 	skb_reset_mac_header(skb);
3340 
3341 	if (rtm->rtm_flags & RTM_F_FIB_MATCH) {
3342 		struct fib_rt_info fri;
3343 
3344 		if (!res.fi) {
3345 			err = fib_props[res.type].error;
3346 			if (!err)
3347 				err = -EHOSTUNREACH;
3348 			goto errout_rcu;
3349 		}
3350 		fri.fi = res.fi;
3351 		fri.tb_id = table_id;
3352 		fri.dst = res.prefix;
3353 		fri.dst_len = res.prefixlen;
3354 		fri.dscp = inet_dsfield_to_dscp(fl4.flowi4_tos);
3355 		fri.type = rt->rt_type;
3356 		fri.offload = 0;
3357 		fri.trap = 0;
3358 		fri.offload_failed = 0;
3359 		if (res.fa_head) {
3360 			struct fib_alias *fa;
3361 
3362 			hlist_for_each_entry_rcu(fa, res.fa_head, fa_list) {
3363 				u8 slen = 32 - fri.dst_len;
3364 
3365 				if (fa->fa_slen == slen &&
3366 				    fa->tb_id == fri.tb_id &&
3367 				    fa->fa_dscp == fri.dscp &&
3368 				    fa->fa_info == res.fi &&
3369 				    fa->fa_type == fri.type) {
3370 					fri.offload = READ_ONCE(fa->offload);
3371 					fri.trap = READ_ONCE(fa->trap);
3372 					fri.offload_failed =
3373 						READ_ONCE(fa->offload_failed);
3374 					break;
3375 				}
3376 			}
3377 		}
3378 		err = fib_dump_info(skb, NETLINK_CB(in_skb).portid,
3379 				    nlh->nlmsg_seq, RTM_NEWROUTE, &fri, 0);
3380 	} else {
3381 		err = rt_fill_info(net, dst, src, rt, table_id, &fl4, skb,
3382 				   NETLINK_CB(in_skb).portid,
3383 				   nlh->nlmsg_seq, 0);
3384 	}
3385 	if (err < 0)
3386 		goto errout_rcu;
3387 
3388 	rcu_read_unlock();
3389 
3390 	err = rtnl_unicast(skb, net, NETLINK_CB(in_skb).portid);
3391 
3392 errout_free:
3393 	return err;
3394 errout_rcu:
3395 	rcu_read_unlock();
3396 	kfree_skb(skb);
3397 	goto errout_free;
3398 }
3399 
3400 void ip_rt_multicast_event(struct in_device *in_dev)
3401 {
3402 	rt_cache_flush(dev_net(in_dev->dev));
3403 }
3404 
3405 #ifdef CONFIG_SYSCTL
3406 static int ip_rt_gc_interval __read_mostly  = 60 * HZ;
3407 static int ip_rt_gc_min_interval __read_mostly	= HZ / 2;
3408 static int ip_rt_gc_elasticity __read_mostly	= 8;
3409 static int ip_min_valid_pmtu __read_mostly	= IPV4_MIN_MTU;
3410 
3411 static int ipv4_sysctl_rtcache_flush(struct ctl_table *__ctl, int write,
3412 		void *buffer, size_t *lenp, loff_t *ppos)
3413 {
3414 	struct net *net = (struct net *)__ctl->extra1;
3415 
3416 	if (write) {
3417 		rt_cache_flush(net);
3418 		fnhe_genid_bump(net);
3419 		return 0;
3420 	}
3421 
3422 	return -EINVAL;
3423 }
3424 
3425 static struct ctl_table ipv4_route_table[] = {
3426 	{
3427 		.procname	= "gc_thresh",
3428 		.data		= &ipv4_dst_ops.gc_thresh,
3429 		.maxlen		= sizeof(int),
3430 		.mode		= 0644,
3431 		.proc_handler	= proc_dointvec,
3432 	},
3433 	{
3434 		.procname	= "max_size",
3435 		.data		= &ip_rt_max_size,
3436 		.maxlen		= sizeof(int),
3437 		.mode		= 0644,
3438 		.proc_handler	= proc_dointvec,
3439 	},
3440 	{
3441 		/*  Deprecated. Use gc_min_interval_ms */
3442 
3443 		.procname	= "gc_min_interval",
3444 		.data		= &ip_rt_gc_min_interval,
3445 		.maxlen		= sizeof(int),
3446 		.mode		= 0644,
3447 		.proc_handler	= proc_dointvec_jiffies,
3448 	},
3449 	{
3450 		.procname	= "gc_min_interval_ms",
3451 		.data		= &ip_rt_gc_min_interval,
3452 		.maxlen		= sizeof(int),
3453 		.mode		= 0644,
3454 		.proc_handler	= proc_dointvec_ms_jiffies,
3455 	},
3456 	{
3457 		.procname	= "gc_timeout",
3458 		.data		= &ip_rt_gc_timeout,
3459 		.maxlen		= sizeof(int),
3460 		.mode		= 0644,
3461 		.proc_handler	= proc_dointvec_jiffies,
3462 	},
3463 	{
3464 		.procname	= "gc_interval",
3465 		.data		= &ip_rt_gc_interval,
3466 		.maxlen		= sizeof(int),
3467 		.mode		= 0644,
3468 		.proc_handler	= proc_dointvec_jiffies,
3469 	},
3470 	{
3471 		.procname	= "redirect_load",
3472 		.data		= &ip_rt_redirect_load,
3473 		.maxlen		= sizeof(int),
3474 		.mode		= 0644,
3475 		.proc_handler	= proc_dointvec,
3476 	},
3477 	{
3478 		.procname	= "redirect_number",
3479 		.data		= &ip_rt_redirect_number,
3480 		.maxlen		= sizeof(int),
3481 		.mode		= 0644,
3482 		.proc_handler	= proc_dointvec,
3483 	},
3484 	{
3485 		.procname	= "redirect_silence",
3486 		.data		= &ip_rt_redirect_silence,
3487 		.maxlen		= sizeof(int),
3488 		.mode		= 0644,
3489 		.proc_handler	= proc_dointvec,
3490 	},
3491 	{
3492 		.procname	= "error_cost",
3493 		.data		= &ip_rt_error_cost,
3494 		.maxlen		= sizeof(int),
3495 		.mode		= 0644,
3496 		.proc_handler	= proc_dointvec,
3497 	},
3498 	{
3499 		.procname	= "error_burst",
3500 		.data		= &ip_rt_error_burst,
3501 		.maxlen		= sizeof(int),
3502 		.mode		= 0644,
3503 		.proc_handler	= proc_dointvec,
3504 	},
3505 	{
3506 		.procname	= "gc_elasticity",
3507 		.data		= &ip_rt_gc_elasticity,
3508 		.maxlen		= sizeof(int),
3509 		.mode		= 0644,
3510 		.proc_handler	= proc_dointvec,
3511 	},
3512 	{ }
3513 };
3514 
3515 static const char ipv4_route_flush_procname[] = "flush";
3516 
3517 static struct ctl_table ipv4_route_netns_table[] = {
3518 	{
3519 		.procname	= ipv4_route_flush_procname,
3520 		.maxlen		= sizeof(int),
3521 		.mode		= 0200,
3522 		.proc_handler	= ipv4_sysctl_rtcache_flush,
3523 	},
3524 	{
3525 		.procname       = "min_pmtu",
3526 		.data           = &init_net.ipv4.ip_rt_min_pmtu,
3527 		.maxlen         = sizeof(int),
3528 		.mode           = 0644,
3529 		.proc_handler   = proc_dointvec_minmax,
3530 		.extra1         = &ip_min_valid_pmtu,
3531 	},
3532 	{
3533 		.procname       = "mtu_expires",
3534 		.data           = &init_net.ipv4.ip_rt_mtu_expires,
3535 		.maxlen         = sizeof(int),
3536 		.mode           = 0644,
3537 		.proc_handler   = proc_dointvec_jiffies,
3538 	},
3539 	{
3540 		.procname   = "min_adv_mss",
3541 		.data       = &init_net.ipv4.ip_rt_min_advmss,
3542 		.maxlen     = sizeof(int),
3543 		.mode       = 0644,
3544 		.proc_handler   = proc_dointvec,
3545 	},
3546 	{ },
3547 };
3548 
3549 static __net_init int sysctl_route_net_init(struct net *net)
3550 {
3551 	struct ctl_table *tbl;
3552 	size_t table_size = ARRAY_SIZE(ipv4_route_netns_table);
3553 
3554 	tbl = ipv4_route_netns_table;
3555 	if (!net_eq(net, &init_net)) {
3556 		int i;
3557 
3558 		tbl = kmemdup(tbl, sizeof(ipv4_route_netns_table), GFP_KERNEL);
3559 		if (!tbl)
3560 			goto err_dup;
3561 
3562 		/* Don't export non-whitelisted sysctls to unprivileged users */
3563 		if (net->user_ns != &init_user_ns) {
3564 			if (tbl[0].procname != ipv4_route_flush_procname) {
3565 				tbl[0].procname = NULL;
3566 				table_size = 0;
3567 			}
3568 		}
3569 
3570 		/* Update the variables to point into the current struct net
3571 		 * except for the first element flush
3572 		 */
3573 		for (i = 1; i < ARRAY_SIZE(ipv4_route_netns_table) - 1; i++)
3574 			tbl[i].data += (void *)net - (void *)&init_net;
3575 	}
3576 	tbl[0].extra1 = net;
3577 
3578 	net->ipv4.route_hdr = register_net_sysctl_sz(net, "net/ipv4/route",
3579 						     tbl, table_size);
3580 	if (!net->ipv4.route_hdr)
3581 		goto err_reg;
3582 	return 0;
3583 
3584 err_reg:
3585 	if (tbl != ipv4_route_netns_table)
3586 		kfree(tbl);
3587 err_dup:
3588 	return -ENOMEM;
3589 }
3590 
3591 static __net_exit void sysctl_route_net_exit(struct net *net)
3592 {
3593 	struct ctl_table *tbl;
3594 
3595 	tbl = net->ipv4.route_hdr->ctl_table_arg;
3596 	unregister_net_sysctl_table(net->ipv4.route_hdr);
3597 	BUG_ON(tbl == ipv4_route_netns_table);
3598 	kfree(tbl);
3599 }
3600 
3601 static __net_initdata struct pernet_operations sysctl_route_ops = {
3602 	.init = sysctl_route_net_init,
3603 	.exit = sysctl_route_net_exit,
3604 };
3605 #endif
3606 
3607 static __net_init int netns_ip_rt_init(struct net *net)
3608 {
3609 	/* Set default value for namespaceified sysctls */
3610 	net->ipv4.ip_rt_min_pmtu = DEFAULT_MIN_PMTU;
3611 	net->ipv4.ip_rt_mtu_expires = DEFAULT_MTU_EXPIRES;
3612 	net->ipv4.ip_rt_min_advmss = DEFAULT_MIN_ADVMSS;
3613 	return 0;
3614 }
3615 
3616 static struct pernet_operations __net_initdata ip_rt_ops = {
3617 	.init = netns_ip_rt_init,
3618 };
3619 
3620 static __net_init int rt_genid_init(struct net *net)
3621 {
3622 	atomic_set(&net->ipv4.rt_genid, 0);
3623 	atomic_set(&net->fnhe_genid, 0);
3624 	atomic_set(&net->ipv4.dev_addr_genid, get_random_u32());
3625 	return 0;
3626 }
3627 
3628 static __net_initdata struct pernet_operations rt_genid_ops = {
3629 	.init = rt_genid_init,
3630 };
3631 
3632 static int __net_init ipv4_inetpeer_init(struct net *net)
3633 {
3634 	struct inet_peer_base *bp = kmalloc(sizeof(*bp), GFP_KERNEL);
3635 
3636 	if (!bp)
3637 		return -ENOMEM;
3638 	inet_peer_base_init(bp);
3639 	net->ipv4.peers = bp;
3640 	return 0;
3641 }
3642 
3643 static void __net_exit ipv4_inetpeer_exit(struct net *net)
3644 {
3645 	struct inet_peer_base *bp = net->ipv4.peers;
3646 
3647 	net->ipv4.peers = NULL;
3648 	inetpeer_invalidate_tree(bp);
3649 	kfree(bp);
3650 }
3651 
3652 static __net_initdata struct pernet_operations ipv4_inetpeer_ops = {
3653 	.init	=	ipv4_inetpeer_init,
3654 	.exit	=	ipv4_inetpeer_exit,
3655 };
3656 
3657 #ifdef CONFIG_IP_ROUTE_CLASSID
3658 struct ip_rt_acct __percpu *ip_rt_acct __read_mostly;
3659 #endif /* CONFIG_IP_ROUTE_CLASSID */
3660 
3661 int __init ip_rt_init(void)
3662 {
3663 	void *idents_hash;
3664 	int cpu;
3665 
3666 	/* For modern hosts, this will use 2 MB of memory */
3667 	idents_hash = alloc_large_system_hash("IP idents",
3668 					      sizeof(*ip_idents) + sizeof(*ip_tstamps),
3669 					      0,
3670 					      16, /* one bucket per 64 KB */
3671 					      HASH_ZERO,
3672 					      NULL,
3673 					      &ip_idents_mask,
3674 					      2048,
3675 					      256*1024);
3676 
3677 	ip_idents = idents_hash;
3678 
3679 	get_random_bytes(ip_idents, (ip_idents_mask + 1) * sizeof(*ip_idents));
3680 
3681 	ip_tstamps = idents_hash + (ip_idents_mask + 1) * sizeof(*ip_idents);
3682 
3683 	for_each_possible_cpu(cpu) {
3684 		struct uncached_list *ul = &per_cpu(rt_uncached_list, cpu);
3685 
3686 		INIT_LIST_HEAD(&ul->head);
3687 		INIT_LIST_HEAD(&ul->quarantine);
3688 		spin_lock_init(&ul->lock);
3689 	}
3690 #ifdef CONFIG_IP_ROUTE_CLASSID
3691 	ip_rt_acct = __alloc_percpu(256 * sizeof(struct ip_rt_acct), __alignof__(struct ip_rt_acct));
3692 	if (!ip_rt_acct)
3693 		panic("IP: failed to allocate ip_rt_acct\n");
3694 #endif
3695 
3696 	ipv4_dst_ops.kmem_cachep =
3697 		kmem_cache_create("ip_dst_cache", sizeof(struct rtable), 0,
3698 				  SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
3699 
3700 	ipv4_dst_blackhole_ops.kmem_cachep = ipv4_dst_ops.kmem_cachep;
3701 
3702 	if (dst_entries_init(&ipv4_dst_ops) < 0)
3703 		panic("IP: failed to allocate ipv4_dst_ops counter\n");
3704 
3705 	if (dst_entries_init(&ipv4_dst_blackhole_ops) < 0)
3706 		panic("IP: failed to allocate ipv4_dst_blackhole_ops counter\n");
3707 
3708 	ipv4_dst_ops.gc_thresh = ~0;
3709 	ip_rt_max_size = INT_MAX;
3710 
3711 	devinet_init();
3712 	ip_fib_init();
3713 
3714 	if (ip_rt_proc_init())
3715 		pr_err("Unable to create route proc files\n");
3716 #ifdef CONFIG_XFRM
3717 	xfrm_init();
3718 	xfrm4_init();
3719 #endif
3720 	rtnl_register(PF_INET, RTM_GETROUTE, inet_rtm_getroute, NULL,
3721 		      RTNL_FLAG_DOIT_UNLOCKED);
3722 
3723 #ifdef CONFIG_SYSCTL
3724 	register_pernet_subsys(&sysctl_route_ops);
3725 #endif
3726 	register_pernet_subsys(&ip_rt_ops);
3727 	register_pernet_subsys(&rt_genid_ops);
3728 	register_pernet_subsys(&ipv4_inetpeer_ops);
3729 	return 0;
3730 }
3731 
3732 #ifdef CONFIG_SYSCTL
3733 /*
3734  * We really need to sanitize the damn ipv4 init order, then all
3735  * this nonsense will go away.
3736  */
3737 void __init ip_static_sysctl_init(void)
3738 {
3739 	register_net_sysctl(&init_net, "net/ipv4/route", ipv4_route_table);
3740 }
3741 #endif
3742