xref: /openbmc/linux/net/ipv4/route.c (revision fd5e9fccbd504c5179ab57ff695c610bca8809d6)
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 void		ipv4_negative_advice(struct sock *sk,
136 					     struct dst_entry *dst);
137 static void		 ipv4_link_failure(struct sk_buff *skb);
138 static void		 ip_rt_update_pmtu(struct dst_entry *dst, struct sock *sk,
139 					   struct sk_buff *skb, u32 mtu,
140 					   bool confirm_neigh);
141 static void		 ip_do_redirect(struct dst_entry *dst, struct sock *sk,
142 					struct sk_buff *skb);
143 static void		ipv4_dst_destroy(struct dst_entry *dst);
144 
ipv4_cow_metrics(struct dst_entry * dst,unsigned long old)145 static u32 *ipv4_cow_metrics(struct dst_entry *dst, unsigned long old)
146 {
147 	WARN_ON(1);
148 	return NULL;
149 }
150 
151 static struct neighbour *ipv4_neigh_lookup(const struct dst_entry *dst,
152 					   struct sk_buff *skb,
153 					   const void *daddr);
154 static void ipv4_confirm_neigh(const struct dst_entry *dst, const void *daddr);
155 
156 static struct dst_ops ipv4_dst_ops = {
157 	.family =		AF_INET,
158 	.check =		ipv4_dst_check,
159 	.default_advmss =	ipv4_default_advmss,
160 	.mtu =			ipv4_mtu,
161 	.cow_metrics =		ipv4_cow_metrics,
162 	.destroy =		ipv4_dst_destroy,
163 	.negative_advice =	ipv4_negative_advice,
164 	.link_failure =		ipv4_link_failure,
165 	.update_pmtu =		ip_rt_update_pmtu,
166 	.redirect =		ip_do_redirect,
167 	.local_out =		__ip_local_out,
168 	.neigh_lookup =		ipv4_neigh_lookup,
169 	.confirm_neigh =	ipv4_confirm_neigh,
170 };
171 
172 #define ECN_OR_COST(class)	TC_PRIO_##class
173 
174 const __u8 ip_tos2prio[16] = {
175 	TC_PRIO_BESTEFFORT,
176 	ECN_OR_COST(BESTEFFORT),
177 	TC_PRIO_BESTEFFORT,
178 	ECN_OR_COST(BESTEFFORT),
179 	TC_PRIO_BULK,
180 	ECN_OR_COST(BULK),
181 	TC_PRIO_BULK,
182 	ECN_OR_COST(BULK),
183 	TC_PRIO_INTERACTIVE,
184 	ECN_OR_COST(INTERACTIVE),
185 	TC_PRIO_INTERACTIVE,
186 	ECN_OR_COST(INTERACTIVE),
187 	TC_PRIO_INTERACTIVE_BULK,
188 	ECN_OR_COST(INTERACTIVE_BULK),
189 	TC_PRIO_INTERACTIVE_BULK,
190 	ECN_OR_COST(INTERACTIVE_BULK)
191 };
192 EXPORT_SYMBOL(ip_tos2prio);
193 
194 static DEFINE_PER_CPU(struct rt_cache_stat, rt_cache_stat);
195 #define RT_CACHE_STAT_INC(field) raw_cpu_inc(rt_cache_stat.field)
196 
197 #ifdef CONFIG_PROC_FS
rt_cache_seq_start(struct seq_file * seq,loff_t * pos)198 static void *rt_cache_seq_start(struct seq_file *seq, loff_t *pos)
199 {
200 	if (*pos)
201 		return NULL;
202 	return SEQ_START_TOKEN;
203 }
204 
rt_cache_seq_next(struct seq_file * seq,void * v,loff_t * pos)205 static void *rt_cache_seq_next(struct seq_file *seq, void *v, loff_t *pos)
206 {
207 	++*pos;
208 	return NULL;
209 }
210 
rt_cache_seq_stop(struct seq_file * seq,void * v)211 static void rt_cache_seq_stop(struct seq_file *seq, void *v)
212 {
213 }
214 
rt_cache_seq_show(struct seq_file * seq,void * v)215 static int rt_cache_seq_show(struct seq_file *seq, void *v)
216 {
217 	if (v == SEQ_START_TOKEN)
218 		seq_printf(seq, "%-127s\n",
219 			   "Iface\tDestination\tGateway \tFlags\t\tRefCnt\tUse\t"
220 			   "Metric\tSource\t\tMTU\tWindow\tIRTT\tTOS\tHHRef\t"
221 			   "HHUptod\tSpecDst");
222 	return 0;
223 }
224 
225 static const struct seq_operations rt_cache_seq_ops = {
226 	.start  = rt_cache_seq_start,
227 	.next   = rt_cache_seq_next,
228 	.stop   = rt_cache_seq_stop,
229 	.show   = rt_cache_seq_show,
230 };
231 
rt_cpu_seq_start(struct seq_file * seq,loff_t * pos)232 static void *rt_cpu_seq_start(struct seq_file *seq, loff_t *pos)
233 {
234 	int cpu;
235 
236 	if (*pos == 0)
237 		return SEQ_START_TOKEN;
238 
239 	for (cpu = *pos-1; cpu < nr_cpu_ids; ++cpu) {
240 		if (!cpu_possible(cpu))
241 			continue;
242 		*pos = cpu+1;
243 		return &per_cpu(rt_cache_stat, cpu);
244 	}
245 	return NULL;
246 }
247 
rt_cpu_seq_next(struct seq_file * seq,void * v,loff_t * pos)248 static void *rt_cpu_seq_next(struct seq_file *seq, void *v, loff_t *pos)
249 {
250 	int cpu;
251 
252 	for (cpu = *pos; cpu < nr_cpu_ids; ++cpu) {
253 		if (!cpu_possible(cpu))
254 			continue;
255 		*pos = cpu+1;
256 		return &per_cpu(rt_cache_stat, cpu);
257 	}
258 	(*pos)++;
259 	return NULL;
260 
261 }
262 
rt_cpu_seq_stop(struct seq_file * seq,void * v)263 static void rt_cpu_seq_stop(struct seq_file *seq, void *v)
264 {
265 
266 }
267 
rt_cpu_seq_show(struct seq_file * seq,void * v)268 static int rt_cpu_seq_show(struct seq_file *seq, void *v)
269 {
270 	struct rt_cache_stat *st = v;
271 
272 	if (v == SEQ_START_TOKEN) {
273 		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");
274 		return 0;
275 	}
276 
277 	seq_printf(seq, "%08x %08x %08x    %08x   %08x    %08x %08x       "
278 			"%08x       %08x %08x     %08x    %08x %08x   "
279 			"%08x     %08x        %08x        %08x\n",
280 		   dst_entries_get_slow(&ipv4_dst_ops),
281 		   0, /* st->in_hit */
282 		   st->in_slow_tot,
283 		   st->in_slow_mc,
284 		   st->in_no_route,
285 		   st->in_brd,
286 		   st->in_martian_dst,
287 		   st->in_martian_src,
288 
289 		   0, /* st->out_hit */
290 		   st->out_slow_tot,
291 		   st->out_slow_mc,
292 
293 		   0, /* st->gc_total */
294 		   0, /* st->gc_ignored */
295 		   0, /* st->gc_goal_miss */
296 		   0, /* st->gc_dst_overflow */
297 		   0, /* st->in_hlist_search */
298 		   0  /* st->out_hlist_search */
299 		);
300 	return 0;
301 }
302 
303 static const struct seq_operations rt_cpu_seq_ops = {
304 	.start  = rt_cpu_seq_start,
305 	.next   = rt_cpu_seq_next,
306 	.stop   = rt_cpu_seq_stop,
307 	.show   = rt_cpu_seq_show,
308 };
309 
310 #ifdef CONFIG_IP_ROUTE_CLASSID
rt_acct_proc_show(struct seq_file * m,void * v)311 static int rt_acct_proc_show(struct seq_file *m, void *v)
312 {
313 	struct ip_rt_acct *dst, *src;
314 	unsigned int i, j;
315 
316 	dst = kcalloc(256, sizeof(struct ip_rt_acct), GFP_KERNEL);
317 	if (!dst)
318 		return -ENOMEM;
319 
320 	for_each_possible_cpu(i) {
321 		src = (struct ip_rt_acct *)per_cpu_ptr(ip_rt_acct, i);
322 		for (j = 0; j < 256; j++) {
323 			dst[j].o_bytes   += src[j].o_bytes;
324 			dst[j].o_packets += src[j].o_packets;
325 			dst[j].i_bytes   += src[j].i_bytes;
326 			dst[j].i_packets += src[j].i_packets;
327 		}
328 	}
329 
330 	seq_write(m, dst, 256 * sizeof(struct ip_rt_acct));
331 	kfree(dst);
332 	return 0;
333 }
334 #endif
335 
ip_rt_do_proc_init(struct net * net)336 static int __net_init ip_rt_do_proc_init(struct net *net)
337 {
338 	struct proc_dir_entry *pde;
339 
340 	pde = proc_create_seq("rt_cache", 0444, net->proc_net,
341 			      &rt_cache_seq_ops);
342 	if (!pde)
343 		goto err1;
344 
345 	pde = proc_create_seq("rt_cache", 0444, net->proc_net_stat,
346 			      &rt_cpu_seq_ops);
347 	if (!pde)
348 		goto err2;
349 
350 #ifdef CONFIG_IP_ROUTE_CLASSID
351 	pde = proc_create_single("rt_acct", 0, net->proc_net,
352 			rt_acct_proc_show);
353 	if (!pde)
354 		goto err3;
355 #endif
356 	return 0;
357 
358 #ifdef CONFIG_IP_ROUTE_CLASSID
359 err3:
360 	remove_proc_entry("rt_cache", net->proc_net_stat);
361 #endif
362 err2:
363 	remove_proc_entry("rt_cache", net->proc_net);
364 err1:
365 	return -ENOMEM;
366 }
367 
ip_rt_do_proc_exit(struct net * net)368 static void __net_exit ip_rt_do_proc_exit(struct net *net)
369 {
370 	remove_proc_entry("rt_cache", net->proc_net_stat);
371 	remove_proc_entry("rt_cache", net->proc_net);
372 #ifdef CONFIG_IP_ROUTE_CLASSID
373 	remove_proc_entry("rt_acct", net->proc_net);
374 #endif
375 }
376 
377 static struct pernet_operations ip_rt_proc_ops __net_initdata =  {
378 	.init = ip_rt_do_proc_init,
379 	.exit = ip_rt_do_proc_exit,
380 };
381 
ip_rt_proc_init(void)382 static int __init ip_rt_proc_init(void)
383 {
384 	return register_pernet_subsys(&ip_rt_proc_ops);
385 }
386 
387 #else
ip_rt_proc_init(void)388 static inline int ip_rt_proc_init(void)
389 {
390 	return 0;
391 }
392 #endif /* CONFIG_PROC_FS */
393 
rt_is_expired(const struct rtable * rth)394 static inline bool rt_is_expired(const struct rtable *rth)
395 {
396 	bool res;
397 
398 	rcu_read_lock();
399 	res = rth->rt_genid != rt_genid_ipv4(dev_net_rcu(rth->dst.dev));
400 	rcu_read_unlock();
401 
402 	return res;
403 }
404 
rt_cache_flush(struct net * net)405 void rt_cache_flush(struct net *net)
406 {
407 	rt_genid_bump_ipv4(net);
408 }
409 
ipv4_neigh_lookup(const struct dst_entry * dst,struct sk_buff * skb,const void * daddr)410 static struct neighbour *ipv4_neigh_lookup(const struct dst_entry *dst,
411 					   struct sk_buff *skb,
412 					   const void *daddr)
413 {
414 	const struct rtable *rt = container_of(dst, struct rtable, dst);
415 	struct net_device *dev = dst->dev;
416 	struct neighbour *n;
417 
418 	rcu_read_lock();
419 
420 	if (likely(rt->rt_gw_family == AF_INET)) {
421 		n = ip_neigh_gw4(dev, rt->rt_gw4);
422 	} else if (rt->rt_gw_family == AF_INET6) {
423 		n = ip_neigh_gw6(dev, &rt->rt_gw6);
424         } else {
425 		__be32 pkey;
426 
427 		pkey = skb ? ip_hdr(skb)->daddr : *((__be32 *) daddr);
428 		n = ip_neigh_gw4(dev, pkey);
429 	}
430 
431 	if (!IS_ERR(n) && !refcount_inc_not_zero(&n->refcnt))
432 		n = NULL;
433 
434 	rcu_read_unlock();
435 
436 	return n;
437 }
438 
ipv4_confirm_neigh(const struct dst_entry * dst,const void * daddr)439 static void ipv4_confirm_neigh(const struct dst_entry *dst, const void *daddr)
440 {
441 	const struct rtable *rt = container_of(dst, struct rtable, dst);
442 	struct net_device *dev = dst->dev;
443 	const __be32 *pkey = daddr;
444 
445 	if (rt->rt_gw_family == AF_INET) {
446 		pkey = (const __be32 *)&rt->rt_gw4;
447 	} else if (rt->rt_gw_family == AF_INET6) {
448 		return __ipv6_confirm_neigh_stub(dev, &rt->rt_gw6);
449 	} else if (!daddr ||
450 		 (rt->rt_flags &
451 		  (RTCF_MULTICAST | RTCF_BROADCAST | RTCF_LOCAL))) {
452 		return;
453 	}
454 	__ipv4_confirm_neigh(dev, *(__force u32 *)pkey);
455 }
456 
457 /* Hash tables of size 2048..262144 depending on RAM size.
458  * Each bucket uses 8 bytes.
459  */
460 static u32 ip_idents_mask __read_mostly;
461 static atomic_t *ip_idents __read_mostly;
462 static u32 *ip_tstamps __read_mostly;
463 
464 /* In order to protect privacy, we add a perturbation to identifiers
465  * if one generator is seldom used. This makes hard for an attacker
466  * to infer how many packets were sent between two points in time.
467  */
ip_idents_reserve(u32 hash,int segs)468 static u32 ip_idents_reserve(u32 hash, int segs)
469 {
470 	u32 bucket, old, now = (u32)jiffies;
471 	atomic_t *p_id;
472 	u32 *p_tstamp;
473 	u32 delta = 0;
474 
475 	bucket = hash & ip_idents_mask;
476 	p_tstamp = ip_tstamps + bucket;
477 	p_id = ip_idents + bucket;
478 	old = READ_ONCE(*p_tstamp);
479 
480 	if (old != now && cmpxchg(p_tstamp, old, now) == old)
481 		delta = get_random_u32_below(now - old);
482 
483 	/* If UBSAN reports an error there, please make sure your compiler
484 	 * supports -fno-strict-overflow before reporting it that was a bug
485 	 * in UBSAN, and it has been fixed in GCC-8.
486 	 */
487 	return atomic_add_return(segs + delta, p_id) - segs;
488 }
489 
__ip_select_ident(struct net * net,struct iphdr * iph,int segs)490 void __ip_select_ident(struct net *net, struct iphdr *iph, int segs)
491 {
492 	u32 hash, id;
493 
494 	/* Note the following code is not safe, but this is okay. */
495 	if (unlikely(siphash_key_is_zero(&net->ipv4.ip_id_key)))
496 		get_random_bytes(&net->ipv4.ip_id_key,
497 				 sizeof(net->ipv4.ip_id_key));
498 
499 	hash = siphash_3u32((__force u32)iph->daddr,
500 			    (__force u32)iph->saddr,
501 			    iph->protocol,
502 			    &net->ipv4.ip_id_key);
503 	id = ip_idents_reserve(hash, segs);
504 	iph->id = htons(id);
505 }
506 EXPORT_SYMBOL(__ip_select_ident);
507 
ip_rt_fix_tos(struct flowi4 * fl4)508 static void ip_rt_fix_tos(struct flowi4 *fl4)
509 {
510 	__u8 tos = RT_FL_TOS(fl4);
511 
512 	fl4->flowi4_tos = tos & IPTOS_RT_MASK;
513 	if (tos & RTO_ONLINK)
514 		fl4->flowi4_scope = RT_SCOPE_LINK;
515 }
516 
__build_flow_key(const struct net * net,struct flowi4 * fl4,const struct sock * sk,const struct iphdr * iph,int oif,__u8 tos,u8 prot,u32 mark,int flow_flags)517 static void __build_flow_key(const struct net *net, struct flowi4 *fl4,
518 			     const struct sock *sk, const struct iphdr *iph,
519 			     int oif, __u8 tos, u8 prot, u32 mark,
520 			     int flow_flags)
521 {
522 	__u8 scope = RT_SCOPE_UNIVERSE;
523 
524 	if (sk) {
525 		oif = sk->sk_bound_dev_if;
526 		mark = READ_ONCE(sk->sk_mark);
527 		tos = ip_sock_rt_tos(sk);
528 		scope = ip_sock_rt_scope(sk);
529 		prot = inet_test_bit(HDRINCL, sk) ? IPPROTO_RAW :
530 						    sk->sk_protocol;
531 	}
532 
533 	flowi4_init_output(fl4, oif, mark, tos & IPTOS_RT_MASK, scope,
534 			   prot, flow_flags, iph->daddr, iph->saddr, 0, 0,
535 			   sock_net_uid(net, sk));
536 }
537 
build_skb_flow_key(struct flowi4 * fl4,const struct sk_buff * skb,const struct sock * sk)538 static void build_skb_flow_key(struct flowi4 *fl4, const struct sk_buff *skb,
539 			       const struct sock *sk)
540 {
541 	const struct net *net = dev_net(skb->dev);
542 	const struct iphdr *iph = ip_hdr(skb);
543 	int oif = skb->dev->ifindex;
544 	u8 prot = iph->protocol;
545 	u32 mark = skb->mark;
546 	__u8 tos = iph->tos;
547 
548 	__build_flow_key(net, fl4, sk, iph, oif, tos, prot, mark, 0);
549 }
550 
build_sk_flow_key(struct flowi4 * fl4,const struct sock * sk)551 static void build_sk_flow_key(struct flowi4 *fl4, const struct sock *sk)
552 {
553 	const struct inet_sock *inet = inet_sk(sk);
554 	const struct ip_options_rcu *inet_opt;
555 	__be32 daddr = inet->inet_daddr;
556 
557 	rcu_read_lock();
558 	inet_opt = rcu_dereference(inet->inet_opt);
559 	if (inet_opt && inet_opt->opt.srr)
560 		daddr = inet_opt->opt.faddr;
561 	flowi4_init_output(fl4, sk->sk_bound_dev_if, READ_ONCE(sk->sk_mark),
562 			   ip_sock_rt_tos(sk) & IPTOS_RT_MASK,
563 			   ip_sock_rt_scope(sk),
564 			   inet_test_bit(HDRINCL, sk) ?
565 				IPPROTO_RAW : sk->sk_protocol,
566 			   inet_sk_flowi_flags(sk),
567 			   daddr, inet->inet_saddr, 0, 0, sk->sk_uid);
568 	rcu_read_unlock();
569 }
570 
ip_rt_build_flow_key(struct flowi4 * fl4,const struct sock * sk,const struct sk_buff * skb)571 static void ip_rt_build_flow_key(struct flowi4 *fl4, const struct sock *sk,
572 				 const struct sk_buff *skb)
573 {
574 	if (skb)
575 		build_skb_flow_key(fl4, skb, sk);
576 	else
577 		build_sk_flow_key(fl4, sk);
578 }
579 
580 static DEFINE_SPINLOCK(fnhe_lock);
581 
fnhe_flush_routes(struct fib_nh_exception * fnhe)582 static void fnhe_flush_routes(struct fib_nh_exception *fnhe)
583 {
584 	struct rtable *rt;
585 
586 	rt = rcu_dereference(fnhe->fnhe_rth_input);
587 	if (rt) {
588 		RCU_INIT_POINTER(fnhe->fnhe_rth_input, NULL);
589 		dst_dev_put(&rt->dst);
590 		dst_release(&rt->dst);
591 	}
592 	rt = rcu_dereference(fnhe->fnhe_rth_output);
593 	if (rt) {
594 		RCU_INIT_POINTER(fnhe->fnhe_rth_output, NULL);
595 		dst_dev_put(&rt->dst);
596 		dst_release(&rt->dst);
597 	}
598 }
599 
fnhe_remove_oldest(struct fnhe_hash_bucket * hash)600 static void fnhe_remove_oldest(struct fnhe_hash_bucket *hash)
601 {
602 	struct fib_nh_exception __rcu **fnhe_p, **oldest_p;
603 	struct fib_nh_exception *fnhe, *oldest = NULL;
604 
605 	for (fnhe_p = &hash->chain; ; fnhe_p = &fnhe->fnhe_next) {
606 		fnhe = rcu_dereference_protected(*fnhe_p,
607 						 lockdep_is_held(&fnhe_lock));
608 		if (!fnhe)
609 			break;
610 		if (!oldest ||
611 		    time_before(fnhe->fnhe_stamp, oldest->fnhe_stamp)) {
612 			oldest = fnhe;
613 			oldest_p = fnhe_p;
614 		}
615 	}
616 	fnhe_flush_routes(oldest);
617 	*oldest_p = oldest->fnhe_next;
618 	kfree_rcu(oldest, rcu);
619 }
620 
fnhe_hashfun(__be32 daddr)621 static u32 fnhe_hashfun(__be32 daddr)
622 {
623 	static siphash_aligned_key_t fnhe_hash_key;
624 	u64 hval;
625 
626 	net_get_random_once(&fnhe_hash_key, sizeof(fnhe_hash_key));
627 	hval = siphash_1u32((__force u32)daddr, &fnhe_hash_key);
628 	return hash_64(hval, FNHE_HASH_SHIFT);
629 }
630 
fill_route_from_fnhe(struct rtable * rt,struct fib_nh_exception * fnhe)631 static void fill_route_from_fnhe(struct rtable *rt, struct fib_nh_exception *fnhe)
632 {
633 	rt->rt_pmtu = fnhe->fnhe_pmtu;
634 	rt->rt_mtu_locked = fnhe->fnhe_mtu_locked;
635 	rt->dst.expires = fnhe->fnhe_expires;
636 
637 	if (fnhe->fnhe_gw) {
638 		rt->rt_flags |= RTCF_REDIRECTED;
639 		rt->rt_uses_gateway = 1;
640 		rt->rt_gw_family = AF_INET;
641 		rt->rt_gw4 = fnhe->fnhe_gw;
642 	}
643 }
644 
update_or_create_fnhe(struct fib_nh_common * nhc,__be32 daddr,__be32 gw,u32 pmtu,bool lock,unsigned long expires)645 static void update_or_create_fnhe(struct fib_nh_common *nhc, __be32 daddr,
646 				  __be32 gw, u32 pmtu, bool lock,
647 				  unsigned long expires)
648 {
649 	struct fnhe_hash_bucket *hash;
650 	struct fib_nh_exception *fnhe;
651 	struct rtable *rt;
652 	u32 genid, hval;
653 	unsigned int i;
654 	int depth;
655 
656 	genid = fnhe_genid(dev_net(nhc->nhc_dev));
657 	hval = fnhe_hashfun(daddr);
658 
659 	spin_lock_bh(&fnhe_lock);
660 
661 	hash = rcu_dereference(nhc->nhc_exceptions);
662 	if (!hash) {
663 		hash = kcalloc(FNHE_HASH_SIZE, sizeof(*hash), GFP_ATOMIC);
664 		if (!hash)
665 			goto out_unlock;
666 		rcu_assign_pointer(nhc->nhc_exceptions, hash);
667 	}
668 
669 	hash += hval;
670 
671 	depth = 0;
672 	for (fnhe = rcu_dereference(hash->chain); fnhe;
673 	     fnhe = rcu_dereference(fnhe->fnhe_next)) {
674 		if (fnhe->fnhe_daddr == daddr)
675 			break;
676 		depth++;
677 	}
678 
679 	if (fnhe) {
680 		if (fnhe->fnhe_genid != genid)
681 			fnhe->fnhe_genid = genid;
682 		if (gw)
683 			fnhe->fnhe_gw = gw;
684 		if (pmtu) {
685 			fnhe->fnhe_pmtu = pmtu;
686 			fnhe->fnhe_mtu_locked = lock;
687 		}
688 		fnhe->fnhe_expires = max(1UL, expires);
689 		/* Update all cached dsts too */
690 		rt = rcu_dereference(fnhe->fnhe_rth_input);
691 		if (rt)
692 			fill_route_from_fnhe(rt, fnhe);
693 		rt = rcu_dereference(fnhe->fnhe_rth_output);
694 		if (rt)
695 			fill_route_from_fnhe(rt, fnhe);
696 	} else {
697 		/* Randomize max depth to avoid some side channels attacks. */
698 		int max_depth = FNHE_RECLAIM_DEPTH +
699 				get_random_u32_below(FNHE_RECLAIM_DEPTH);
700 
701 		while (depth > max_depth) {
702 			fnhe_remove_oldest(hash);
703 			depth--;
704 		}
705 
706 		fnhe = kzalloc(sizeof(*fnhe), GFP_ATOMIC);
707 		if (!fnhe)
708 			goto out_unlock;
709 
710 		fnhe->fnhe_next = hash->chain;
711 
712 		fnhe->fnhe_genid = genid;
713 		fnhe->fnhe_daddr = daddr;
714 		fnhe->fnhe_gw = gw;
715 		fnhe->fnhe_pmtu = pmtu;
716 		fnhe->fnhe_mtu_locked = lock;
717 		fnhe->fnhe_expires = max(1UL, expires);
718 
719 		rcu_assign_pointer(hash->chain, fnhe);
720 
721 		/* Exception created; mark the cached routes for the nexthop
722 		 * stale, so anyone caching it rechecks if this exception
723 		 * applies to them.
724 		 */
725 		rt = rcu_dereference(nhc->nhc_rth_input);
726 		if (rt)
727 			rt->dst.obsolete = DST_OBSOLETE_KILL;
728 
729 		for_each_possible_cpu(i) {
730 			struct rtable __rcu **prt;
731 
732 			prt = per_cpu_ptr(nhc->nhc_pcpu_rth_output, i);
733 			rt = rcu_dereference(*prt);
734 			if (rt)
735 				rt->dst.obsolete = DST_OBSOLETE_KILL;
736 		}
737 	}
738 
739 	fnhe->fnhe_stamp = jiffies;
740 
741 out_unlock:
742 	spin_unlock_bh(&fnhe_lock);
743 }
744 
__ip_do_redirect(struct rtable * rt,struct sk_buff * skb,struct flowi4 * fl4,bool kill_route)745 static void __ip_do_redirect(struct rtable *rt, struct sk_buff *skb, struct flowi4 *fl4,
746 			     bool kill_route)
747 {
748 	__be32 new_gw = icmp_hdr(skb)->un.gateway;
749 	__be32 old_gw = ip_hdr(skb)->saddr;
750 	struct net_device *dev = skb->dev;
751 	struct in_device *in_dev;
752 	struct fib_result res;
753 	struct neighbour *n;
754 	struct net *net;
755 
756 	switch (icmp_hdr(skb)->code & 7) {
757 	case ICMP_REDIR_NET:
758 	case ICMP_REDIR_NETTOS:
759 	case ICMP_REDIR_HOST:
760 	case ICMP_REDIR_HOSTTOS:
761 		break;
762 
763 	default:
764 		return;
765 	}
766 
767 	if (rt->rt_gw_family != AF_INET || rt->rt_gw4 != old_gw)
768 		return;
769 
770 	in_dev = __in_dev_get_rcu(dev);
771 	if (!in_dev)
772 		return;
773 
774 	net = dev_net(dev);
775 	if (new_gw == old_gw || !IN_DEV_RX_REDIRECTS(in_dev) ||
776 	    ipv4_is_multicast(new_gw) || ipv4_is_lbcast(new_gw) ||
777 	    ipv4_is_zeronet(new_gw))
778 		goto reject_redirect;
779 
780 	if (!IN_DEV_SHARED_MEDIA(in_dev)) {
781 		if (!inet_addr_onlink(in_dev, new_gw, old_gw))
782 			goto reject_redirect;
783 		if (IN_DEV_SEC_REDIRECTS(in_dev) && ip_fib_check_default(new_gw, dev))
784 			goto reject_redirect;
785 	} else {
786 		if (inet_addr_type(net, new_gw) != RTN_UNICAST)
787 			goto reject_redirect;
788 	}
789 
790 	n = __ipv4_neigh_lookup(rt->dst.dev, (__force u32)new_gw);
791 	if (!n)
792 		n = neigh_create(&arp_tbl, &new_gw, rt->dst.dev);
793 	if (!IS_ERR(n)) {
794 		if (!(READ_ONCE(n->nud_state) & NUD_VALID)) {
795 			neigh_event_send(n, NULL);
796 		} else {
797 			if (fib_lookup(net, fl4, &res, 0) == 0) {
798 				struct fib_nh_common *nhc;
799 
800 				fib_select_path(net, &res, fl4, skb);
801 				nhc = FIB_RES_NHC(res);
802 				update_or_create_fnhe(nhc, fl4->daddr, new_gw,
803 						0, false,
804 						jiffies + ip_rt_gc_timeout);
805 			}
806 			if (kill_route)
807 				rt->dst.obsolete = DST_OBSOLETE_KILL;
808 			call_netevent_notifiers(NETEVENT_NEIGH_UPDATE, n);
809 		}
810 		neigh_release(n);
811 	}
812 	return;
813 
814 reject_redirect:
815 #ifdef CONFIG_IP_ROUTE_VERBOSE
816 	if (IN_DEV_LOG_MARTIANS(in_dev)) {
817 		const struct iphdr *iph = (const struct iphdr *) skb->data;
818 		__be32 daddr = iph->daddr;
819 		__be32 saddr = iph->saddr;
820 
821 		net_info_ratelimited("Redirect from %pI4 on %s about %pI4 ignored\n"
822 				     "  Advised path = %pI4 -> %pI4\n",
823 				     &old_gw, dev->name, &new_gw,
824 				     &saddr, &daddr);
825 	}
826 #endif
827 	;
828 }
829 
ip_do_redirect(struct dst_entry * dst,struct sock * sk,struct sk_buff * skb)830 static void ip_do_redirect(struct dst_entry *dst, struct sock *sk, struct sk_buff *skb)
831 {
832 	struct rtable *rt;
833 	struct flowi4 fl4;
834 	const struct iphdr *iph = (const struct iphdr *) skb->data;
835 	struct net *net = dev_net(skb->dev);
836 	int oif = skb->dev->ifindex;
837 	u8 prot = iph->protocol;
838 	u32 mark = skb->mark;
839 	__u8 tos = iph->tos;
840 
841 	rt = (struct rtable *) dst;
842 
843 	__build_flow_key(net, &fl4, sk, iph, oif, tos, prot, mark, 0);
844 	__ip_do_redirect(rt, skb, &fl4, true);
845 }
846 
ipv4_negative_advice(struct sock * sk,struct dst_entry * dst)847 static void ipv4_negative_advice(struct sock *sk,
848 				 struct dst_entry *dst)
849 {
850 	struct rtable *rt = (struct rtable *)dst;
851 
852 	if ((dst->obsolete > 0) ||
853 	    (rt->rt_flags & RTCF_REDIRECTED) ||
854 	    rt->dst.expires)
855 		sk_dst_reset(sk);
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 
ip_rt_send_redirect(struct sk_buff * skb)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 
892 	net = dev_net(rt->dst.dev);
893 	peer = inet_getpeer_v4(net->ipv4.peers, ip_hdr(skb)->saddr, vif);
894 	if (!peer) {
895 		rcu_read_unlock();
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_unlock;
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 		if (IS_ENABLED(CONFIG_IP_ROUTE_VERBOSE) && log_martians &&
930 		    peer->n_redirects == ip_rt_redirect_number)
931 			net_warn_ratelimited("host %pI4/if%d ignores redirects for %pI4 to %pI4\n",
932 					     &ip_hdr(skb)->saddr, inet_iif(skb),
933 					     &ip_hdr(skb)->daddr, &gw);
934 	}
935 out_unlock:
936 	rcu_read_unlock();
937 }
938 
ip_error(struct sk_buff * skb)939 static int ip_error(struct sk_buff *skb)
940 {
941 	struct rtable *rt = skb_rtable(skb);
942 	struct net_device *dev = skb->dev;
943 	struct in_device *in_dev;
944 	struct inet_peer *peer;
945 	unsigned long now;
946 	struct net *net;
947 	SKB_DR(reason);
948 	bool send;
949 	int code;
950 
951 	if (netif_is_l3_master(skb->dev)) {
952 		dev = __dev_get_by_index(dev_net(skb->dev), IPCB(skb)->iif);
953 		if (!dev)
954 			goto out;
955 	}
956 
957 	in_dev = __in_dev_get_rcu(dev);
958 
959 	/* IP on this device is disabled. */
960 	if (!in_dev)
961 		goto out;
962 
963 	net = dev_net(rt->dst.dev);
964 	if (!IN_DEV_FORWARD(in_dev)) {
965 		switch (rt->dst.error) {
966 		case EHOSTUNREACH:
967 			SKB_DR_SET(reason, IP_INADDRERRORS);
968 			__IP_INC_STATS(net, IPSTATS_MIB_INADDRERRORS);
969 			break;
970 
971 		case ENETUNREACH:
972 			SKB_DR_SET(reason, IP_INNOROUTES);
973 			__IP_INC_STATS(net, IPSTATS_MIB_INNOROUTES);
974 			break;
975 		}
976 		goto out;
977 	}
978 
979 	switch (rt->dst.error) {
980 	case EINVAL:
981 	default:
982 		goto out;
983 	case EHOSTUNREACH:
984 		code = ICMP_HOST_UNREACH;
985 		break;
986 	case ENETUNREACH:
987 		code = ICMP_NET_UNREACH;
988 		SKB_DR_SET(reason, IP_INNOROUTES);
989 		__IP_INC_STATS(net, IPSTATS_MIB_INNOROUTES);
990 		break;
991 	case EACCES:
992 		code = ICMP_PKT_FILTERED;
993 		break;
994 	}
995 
996 	rcu_read_lock();
997 	peer = inet_getpeer_v4(net->ipv4.peers, ip_hdr(skb)->saddr,
998 			       l3mdev_master_ifindex_rcu(skb->dev));
999 	send = true;
1000 	if (peer) {
1001 		now = jiffies;
1002 		peer->rate_tokens += now - peer->rate_last;
1003 		if (peer->rate_tokens > ip_rt_error_burst)
1004 			peer->rate_tokens = ip_rt_error_burst;
1005 		peer->rate_last = now;
1006 		if (peer->rate_tokens >= ip_rt_error_cost)
1007 			peer->rate_tokens -= ip_rt_error_cost;
1008 		else
1009 			send = false;
1010 	}
1011 	rcu_read_unlock();
1012 
1013 	if (send)
1014 		icmp_send(skb, ICMP_DEST_UNREACH, code, 0);
1015 
1016 out:	kfree_skb_reason(skb, reason);
1017 	return 0;
1018 }
1019 
__ip_rt_update_pmtu(struct rtable * rt,struct flowi4 * fl4,u32 mtu)1020 static void __ip_rt_update_pmtu(struct rtable *rt, struct flowi4 *fl4, u32 mtu)
1021 {
1022 	struct dst_entry *dst = &rt->dst;
1023 	struct fib_result res;
1024 	bool lock = false;
1025 	struct net *net;
1026 	u32 old_mtu;
1027 
1028 	if (ip_mtu_locked(dst))
1029 		return;
1030 
1031 	old_mtu = ipv4_mtu(dst);
1032 	if (old_mtu < mtu)
1033 		return;
1034 
1035 	rcu_read_lock();
1036 	net = dev_net_rcu(dst->dev);
1037 	if (mtu < net->ipv4.ip_rt_min_pmtu) {
1038 		lock = true;
1039 		mtu = min(old_mtu, net->ipv4.ip_rt_min_pmtu);
1040 	}
1041 
1042 	if (rt->rt_pmtu == mtu && !lock &&
1043 	    time_before(jiffies, dst->expires - net->ipv4.ip_rt_mtu_expires / 2))
1044 		goto out;
1045 
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 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1051 		if (fib_info_num_path(res.fi) > 1) {
1052 			int nhsel;
1053 
1054 			for (nhsel = 0; nhsel < fib_info_num_path(res.fi); nhsel++) {
1055 				nhc = fib_info_nhc(res.fi, nhsel);
1056 				update_or_create_fnhe(nhc, fl4->daddr, 0, mtu, lock,
1057 						      jiffies + net->ipv4.ip_rt_mtu_expires);
1058 			}
1059 			goto out;
1060 		}
1061 #endif /* CONFIG_IP_ROUTE_MULTIPATH */
1062 		nhc = FIB_RES_NHC(res);
1063 		update_or_create_fnhe(nhc, fl4->daddr, 0, mtu, lock,
1064 				      jiffies + net->ipv4.ip_rt_mtu_expires);
1065 	}
1066 out:
1067 	rcu_read_unlock();
1068 }
1069 
ip_rt_update_pmtu(struct dst_entry * dst,struct sock * sk,struct sk_buff * skb,u32 mtu,bool confirm_neigh)1070 static void ip_rt_update_pmtu(struct dst_entry *dst, struct sock *sk,
1071 			      struct sk_buff *skb, u32 mtu,
1072 			      bool confirm_neigh)
1073 {
1074 	struct rtable *rt = (struct rtable *) dst;
1075 	struct flowi4 fl4;
1076 
1077 	ip_rt_build_flow_key(&fl4, sk, skb);
1078 
1079 	/* Don't make lookup fail for bridged encapsulations */
1080 	if (skb && netif_is_any_bridge_port(skb->dev))
1081 		fl4.flowi4_oif = 0;
1082 
1083 	__ip_rt_update_pmtu(rt, &fl4, mtu);
1084 }
1085 
ipv4_update_pmtu(struct sk_buff * skb,struct net * net,u32 mtu,int oif,u8 protocol)1086 void ipv4_update_pmtu(struct sk_buff *skb, struct net *net, u32 mtu,
1087 		      int oif, u8 protocol)
1088 {
1089 	const struct iphdr *iph = (const struct iphdr *)skb->data;
1090 	struct flowi4 fl4;
1091 	struct rtable *rt;
1092 	u32 mark = IP4_REPLY_MARK(net, skb->mark);
1093 
1094 	__build_flow_key(net, &fl4, NULL, iph, oif, iph->tos, protocol, mark,
1095 			 0);
1096 	rt = __ip_route_output_key(net, &fl4);
1097 	if (!IS_ERR(rt)) {
1098 		__ip_rt_update_pmtu(rt, &fl4, mtu);
1099 		ip_rt_put(rt);
1100 	}
1101 }
1102 EXPORT_SYMBOL_GPL(ipv4_update_pmtu);
1103 
__ipv4_sk_update_pmtu(struct sk_buff * skb,struct sock * sk,u32 mtu)1104 static void __ipv4_sk_update_pmtu(struct sk_buff *skb, struct sock *sk, u32 mtu)
1105 {
1106 	const struct iphdr *iph = (const struct iphdr *)skb->data;
1107 	struct flowi4 fl4;
1108 	struct rtable *rt;
1109 
1110 	__build_flow_key(sock_net(sk), &fl4, sk, iph, 0, 0, 0, 0, 0);
1111 
1112 	if (!fl4.flowi4_mark)
1113 		fl4.flowi4_mark = IP4_REPLY_MARK(sock_net(sk), skb->mark);
1114 
1115 	rt = __ip_route_output_key(sock_net(sk), &fl4);
1116 	if (!IS_ERR(rt)) {
1117 		__ip_rt_update_pmtu(rt, &fl4, mtu);
1118 		ip_rt_put(rt);
1119 	}
1120 }
1121 
ipv4_sk_update_pmtu(struct sk_buff * skb,struct sock * sk,u32 mtu)1122 void ipv4_sk_update_pmtu(struct sk_buff *skb, struct sock *sk, u32 mtu)
1123 {
1124 	const struct iphdr *iph = (const struct iphdr *)skb->data;
1125 	struct flowi4 fl4;
1126 	struct rtable *rt;
1127 	struct dst_entry *odst = NULL;
1128 	bool new = false;
1129 	struct net *net = sock_net(sk);
1130 
1131 	bh_lock_sock(sk);
1132 
1133 	if (!ip_sk_accept_pmtu(sk))
1134 		goto out;
1135 
1136 	odst = sk_dst_get(sk);
1137 
1138 	if (sock_owned_by_user(sk) || !odst) {
1139 		__ipv4_sk_update_pmtu(skb, sk, mtu);
1140 		goto out;
1141 	}
1142 
1143 	__build_flow_key(net, &fl4, sk, iph, 0, 0, 0, 0, 0);
1144 
1145 	rt = (struct rtable *)odst;
1146 	if (odst->obsolete && !odst->ops->check(odst, 0)) {
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 	__ip_rt_update_pmtu((struct rtable *)xfrm_dst_path(&rt->dst), &fl4, mtu);
1155 
1156 	if (!dst_check(&rt->dst, 0)) {
1157 		if (new)
1158 			dst_release(&rt->dst);
1159 
1160 		rt = ip_route_output_flow(sock_net(sk), &fl4, sk);
1161 		if (IS_ERR(rt))
1162 			goto out;
1163 
1164 		new = true;
1165 	}
1166 
1167 	if (new)
1168 		sk_dst_set(sk, &rt->dst);
1169 
1170 out:
1171 	bh_unlock_sock(sk);
1172 	dst_release(odst);
1173 }
1174 EXPORT_SYMBOL_GPL(ipv4_sk_update_pmtu);
1175 
ipv4_redirect(struct sk_buff * skb,struct net * net,int oif,u8 protocol)1176 void ipv4_redirect(struct sk_buff *skb, struct net *net,
1177 		   int oif, u8 protocol)
1178 {
1179 	const struct iphdr *iph = (const struct iphdr *)skb->data;
1180 	struct flowi4 fl4;
1181 	struct rtable *rt;
1182 
1183 	__build_flow_key(net, &fl4, NULL, iph, oif, iph->tos, protocol, 0, 0);
1184 	rt = __ip_route_output_key(net, &fl4);
1185 	if (!IS_ERR(rt)) {
1186 		__ip_do_redirect(rt, skb, &fl4, false);
1187 		ip_rt_put(rt);
1188 	}
1189 }
1190 EXPORT_SYMBOL_GPL(ipv4_redirect);
1191 
ipv4_sk_redirect(struct sk_buff * skb,struct sock * sk)1192 void ipv4_sk_redirect(struct sk_buff *skb, struct sock *sk)
1193 {
1194 	const struct iphdr *iph = (const struct iphdr *)skb->data;
1195 	struct flowi4 fl4;
1196 	struct rtable *rt;
1197 	struct net *net = sock_net(sk);
1198 
1199 	__build_flow_key(net, &fl4, sk, iph, 0, 0, 0, 0, 0);
1200 	rt = __ip_route_output_key(net, &fl4);
1201 	if (!IS_ERR(rt)) {
1202 		__ip_do_redirect(rt, skb, &fl4, false);
1203 		ip_rt_put(rt);
1204 	}
1205 }
1206 EXPORT_SYMBOL_GPL(ipv4_sk_redirect);
1207 
ipv4_dst_check(struct dst_entry * dst,u32 cookie)1208 INDIRECT_CALLABLE_SCOPE struct dst_entry *ipv4_dst_check(struct dst_entry *dst,
1209 							 u32 cookie)
1210 {
1211 	struct rtable *rt = (struct rtable *) dst;
1212 
1213 	/* All IPV4 dsts are created with ->obsolete set to the value
1214 	 * DST_OBSOLETE_FORCE_CHK which forces validation calls down
1215 	 * into this function always.
1216 	 *
1217 	 * When a PMTU/redirect information update invalidates a route,
1218 	 * this is indicated by setting obsolete to DST_OBSOLETE_KILL or
1219 	 * DST_OBSOLETE_DEAD.
1220 	 */
1221 	if (dst->obsolete != DST_OBSOLETE_FORCE_CHK || rt_is_expired(rt))
1222 		return NULL;
1223 	return dst;
1224 }
1225 EXPORT_INDIRECT_CALLABLE(ipv4_dst_check);
1226 
ipv4_send_dest_unreach(struct sk_buff * skb)1227 static void ipv4_send_dest_unreach(struct sk_buff *skb)
1228 {
1229 	struct net_device *dev;
1230 	struct ip_options opt;
1231 	int res;
1232 
1233 	/* Recompile ip options since IPCB may not be valid anymore.
1234 	 * Also check we have a reasonable ipv4 header.
1235 	 */
1236 	if (!pskb_network_may_pull(skb, sizeof(struct iphdr)) ||
1237 	    ip_hdr(skb)->version != 4 || ip_hdr(skb)->ihl < 5)
1238 		return;
1239 
1240 	memset(&opt, 0, sizeof(opt));
1241 	if (ip_hdr(skb)->ihl > 5) {
1242 		if (!pskb_network_may_pull(skb, ip_hdr(skb)->ihl * 4))
1243 			return;
1244 		opt.optlen = ip_hdr(skb)->ihl * 4 - sizeof(struct iphdr);
1245 
1246 		rcu_read_lock();
1247 		dev = skb->dev ? skb->dev : skb_rtable(skb)->dst.dev;
1248 		res = __ip_options_compile(dev_net(dev), &opt, skb, NULL);
1249 		rcu_read_unlock();
1250 
1251 		if (res)
1252 			return;
1253 	}
1254 	__icmp_send(skb, ICMP_DEST_UNREACH, ICMP_HOST_UNREACH, 0, &opt);
1255 }
1256 
ipv4_link_failure(struct sk_buff * skb)1257 static void ipv4_link_failure(struct sk_buff *skb)
1258 {
1259 	struct rtable *rt;
1260 
1261 	ipv4_send_dest_unreach(skb);
1262 
1263 	rt = skb_rtable(skb);
1264 	if (rt)
1265 		dst_set_expires(&rt->dst, 0);
1266 }
1267 
ip_rt_bug(struct net * net,struct sock * sk,struct sk_buff * skb)1268 static int ip_rt_bug(struct net *net, struct sock *sk, struct sk_buff *skb)
1269 {
1270 	pr_debug("%s: %pI4 -> %pI4, %s\n",
1271 		 __func__, &ip_hdr(skb)->saddr, &ip_hdr(skb)->daddr,
1272 		 skb->dev ? skb->dev->name : "?");
1273 	kfree_skb(skb);
1274 	WARN_ON(1);
1275 	return 0;
1276 }
1277 
1278 /*
1279  * We do not cache source address of outgoing interface,
1280  * because it is used only by IP RR, TS and SRR options,
1281  * so that it out of fast path.
1282  *
1283  * BTW remember: "addr" is allowed to be not aligned
1284  * in IP options!
1285  */
1286 
ip_rt_get_source(u8 * addr,struct sk_buff * skb,struct rtable * rt)1287 void ip_rt_get_source(u8 *addr, struct sk_buff *skb, struct rtable *rt)
1288 {
1289 	__be32 src;
1290 
1291 	if (rt_is_output_route(rt))
1292 		src = ip_hdr(skb)->saddr;
1293 	else {
1294 		struct fib_result res;
1295 		struct iphdr *iph = ip_hdr(skb);
1296 		struct flowi4 fl4 = {
1297 			.daddr = iph->daddr,
1298 			.saddr = iph->saddr,
1299 			.flowi4_tos = iph->tos & IPTOS_RT_MASK,
1300 			.flowi4_oif = rt->dst.dev->ifindex,
1301 			.flowi4_iif = skb->dev->ifindex,
1302 			.flowi4_mark = skb->mark,
1303 		};
1304 
1305 		rcu_read_lock();
1306 		if (fib_lookup(dev_net(rt->dst.dev), &fl4, &res, 0) == 0)
1307 			src = fib_result_prefsrc(dev_net(rt->dst.dev), &res);
1308 		else
1309 			src = inet_select_addr(rt->dst.dev,
1310 					       rt_nexthop(rt, iph->daddr),
1311 					       RT_SCOPE_UNIVERSE);
1312 		rcu_read_unlock();
1313 	}
1314 	memcpy(addr, &src, 4);
1315 }
1316 
1317 #ifdef CONFIG_IP_ROUTE_CLASSID
set_class_tag(struct rtable * rt,u32 tag)1318 static void set_class_tag(struct rtable *rt, u32 tag)
1319 {
1320 	if (!(rt->dst.tclassid & 0xFFFF))
1321 		rt->dst.tclassid |= tag & 0xFFFF;
1322 	if (!(rt->dst.tclassid & 0xFFFF0000))
1323 		rt->dst.tclassid |= tag & 0xFFFF0000;
1324 }
1325 #endif
1326 
ipv4_default_advmss(const struct dst_entry * dst)1327 static unsigned int ipv4_default_advmss(const struct dst_entry *dst)
1328 {
1329 	unsigned int header_size = sizeof(struct tcphdr) + sizeof(struct iphdr);
1330 	unsigned int advmss;
1331 	struct net *net;
1332 
1333 	rcu_read_lock();
1334 	net = dev_net_rcu(dst->dev);
1335 	advmss = max_t(unsigned int, ipv4_mtu(dst) - header_size,
1336 				   net->ipv4.ip_rt_min_advmss);
1337 	rcu_read_unlock();
1338 
1339 	return min(advmss, IPV4_MAX_PMTU - header_size);
1340 }
1341 
ipv4_mtu(const struct dst_entry * dst)1342 INDIRECT_CALLABLE_SCOPE unsigned int ipv4_mtu(const struct dst_entry *dst)
1343 {
1344 	return ip_dst_mtu_maybe_forward(dst, false);
1345 }
1346 EXPORT_INDIRECT_CALLABLE(ipv4_mtu);
1347 
ip_del_fnhe(struct fib_nh_common * nhc,__be32 daddr)1348 static void ip_del_fnhe(struct fib_nh_common *nhc, __be32 daddr)
1349 {
1350 	struct fnhe_hash_bucket *hash;
1351 	struct fib_nh_exception *fnhe, __rcu **fnhe_p;
1352 	u32 hval = fnhe_hashfun(daddr);
1353 
1354 	spin_lock_bh(&fnhe_lock);
1355 
1356 	hash = rcu_dereference_protected(nhc->nhc_exceptions,
1357 					 lockdep_is_held(&fnhe_lock));
1358 	hash += hval;
1359 
1360 	fnhe_p = &hash->chain;
1361 	fnhe = rcu_dereference_protected(*fnhe_p, lockdep_is_held(&fnhe_lock));
1362 	while (fnhe) {
1363 		if (fnhe->fnhe_daddr == daddr) {
1364 			rcu_assign_pointer(*fnhe_p, rcu_dereference_protected(
1365 				fnhe->fnhe_next, lockdep_is_held(&fnhe_lock)));
1366 			/* set fnhe_daddr to 0 to ensure it won't bind with
1367 			 * new dsts in rt_bind_exception().
1368 			 */
1369 			fnhe->fnhe_daddr = 0;
1370 			fnhe_flush_routes(fnhe);
1371 			kfree_rcu(fnhe, rcu);
1372 			break;
1373 		}
1374 		fnhe_p = &fnhe->fnhe_next;
1375 		fnhe = rcu_dereference_protected(fnhe->fnhe_next,
1376 						 lockdep_is_held(&fnhe_lock));
1377 	}
1378 
1379 	spin_unlock_bh(&fnhe_lock);
1380 }
1381 
find_exception(struct fib_nh_common * nhc,__be32 daddr)1382 static struct fib_nh_exception *find_exception(struct fib_nh_common *nhc,
1383 					       __be32 daddr)
1384 {
1385 	struct fnhe_hash_bucket *hash = rcu_dereference(nhc->nhc_exceptions);
1386 	struct fib_nh_exception *fnhe;
1387 	u32 hval;
1388 
1389 	if (!hash)
1390 		return NULL;
1391 
1392 	hval = fnhe_hashfun(daddr);
1393 
1394 	for (fnhe = rcu_dereference(hash[hval].chain); fnhe;
1395 	     fnhe = rcu_dereference(fnhe->fnhe_next)) {
1396 		if (fnhe->fnhe_daddr == daddr) {
1397 			if (fnhe->fnhe_expires &&
1398 			    time_after(jiffies, fnhe->fnhe_expires)) {
1399 				ip_del_fnhe(nhc, daddr);
1400 				break;
1401 			}
1402 			return fnhe;
1403 		}
1404 	}
1405 	return NULL;
1406 }
1407 
1408 /* MTU selection:
1409  * 1. mtu on route is locked - use it
1410  * 2. mtu from nexthop exception
1411  * 3. mtu from egress device
1412  */
1413 
ip_mtu_from_fib_result(struct fib_result * res,__be32 daddr)1414 u32 ip_mtu_from_fib_result(struct fib_result *res, __be32 daddr)
1415 {
1416 	struct fib_nh_common *nhc = res->nhc;
1417 	struct net_device *dev = nhc->nhc_dev;
1418 	struct fib_info *fi = res->fi;
1419 	u32 mtu = 0;
1420 
1421 	if (READ_ONCE(dev_net(dev)->ipv4.sysctl_ip_fwd_use_pmtu) ||
1422 	    fi->fib_metrics->metrics[RTAX_LOCK - 1] & (1 << RTAX_MTU))
1423 		mtu = fi->fib_mtu;
1424 
1425 	if (likely(!mtu)) {
1426 		struct fib_nh_exception *fnhe;
1427 
1428 		fnhe = find_exception(nhc, daddr);
1429 		if (fnhe && !time_after_eq(jiffies, fnhe->fnhe_expires))
1430 			mtu = fnhe->fnhe_pmtu;
1431 	}
1432 
1433 	if (likely(!mtu))
1434 		mtu = min(READ_ONCE(dev->mtu), IP_MAX_MTU);
1435 
1436 	return mtu - lwtunnel_headroom(nhc->nhc_lwtstate, mtu);
1437 }
1438 
rt_bind_exception(struct rtable * rt,struct fib_nh_exception * fnhe,__be32 daddr,const bool do_cache)1439 static bool rt_bind_exception(struct rtable *rt, struct fib_nh_exception *fnhe,
1440 			      __be32 daddr, const bool do_cache)
1441 {
1442 	bool ret = false;
1443 
1444 	spin_lock_bh(&fnhe_lock);
1445 
1446 	if (daddr == fnhe->fnhe_daddr) {
1447 		struct rtable __rcu **porig;
1448 		struct rtable *orig;
1449 		int genid = fnhe_genid(dev_net(rt->dst.dev));
1450 
1451 		if (rt_is_input_route(rt))
1452 			porig = &fnhe->fnhe_rth_input;
1453 		else
1454 			porig = &fnhe->fnhe_rth_output;
1455 		orig = rcu_dereference(*porig);
1456 
1457 		if (fnhe->fnhe_genid != genid) {
1458 			fnhe->fnhe_genid = genid;
1459 			fnhe->fnhe_gw = 0;
1460 			fnhe->fnhe_pmtu = 0;
1461 			fnhe->fnhe_expires = 0;
1462 			fnhe->fnhe_mtu_locked = false;
1463 			fnhe_flush_routes(fnhe);
1464 			orig = NULL;
1465 		}
1466 		fill_route_from_fnhe(rt, fnhe);
1467 		if (!rt->rt_gw4) {
1468 			rt->rt_gw4 = daddr;
1469 			rt->rt_gw_family = AF_INET;
1470 		}
1471 
1472 		if (do_cache) {
1473 			dst_hold(&rt->dst);
1474 			rcu_assign_pointer(*porig, rt);
1475 			if (orig) {
1476 				dst_dev_put(&orig->dst);
1477 				dst_release(&orig->dst);
1478 			}
1479 			ret = true;
1480 		}
1481 
1482 		fnhe->fnhe_stamp = jiffies;
1483 	}
1484 	spin_unlock_bh(&fnhe_lock);
1485 
1486 	return ret;
1487 }
1488 
rt_cache_route(struct fib_nh_common * nhc,struct rtable * rt)1489 static bool rt_cache_route(struct fib_nh_common *nhc, struct rtable *rt)
1490 {
1491 	struct rtable *orig, *prev, **p;
1492 	bool ret = true;
1493 
1494 	if (rt_is_input_route(rt)) {
1495 		p = (struct rtable **)&nhc->nhc_rth_input;
1496 	} else {
1497 		p = (struct rtable **)raw_cpu_ptr(nhc->nhc_pcpu_rth_output);
1498 	}
1499 	orig = *p;
1500 
1501 	/* hold dst before doing cmpxchg() to avoid race condition
1502 	 * on this dst
1503 	 */
1504 	dst_hold(&rt->dst);
1505 	prev = cmpxchg(p, orig, rt);
1506 	if (prev == orig) {
1507 		if (orig) {
1508 			rt_add_uncached_list(orig);
1509 			dst_release(&orig->dst);
1510 		}
1511 	} else {
1512 		dst_release(&rt->dst);
1513 		ret = false;
1514 	}
1515 
1516 	return ret;
1517 }
1518 
1519 struct uncached_list {
1520 	spinlock_t		lock;
1521 	struct list_head	head;
1522 	struct list_head	quarantine;
1523 };
1524 
1525 static DEFINE_PER_CPU_ALIGNED(struct uncached_list, rt_uncached_list);
1526 
rt_add_uncached_list(struct rtable * rt)1527 void rt_add_uncached_list(struct rtable *rt)
1528 {
1529 	struct uncached_list *ul = raw_cpu_ptr(&rt_uncached_list);
1530 
1531 	rt->dst.rt_uncached_list = ul;
1532 
1533 	spin_lock_bh(&ul->lock);
1534 	list_add_tail(&rt->dst.rt_uncached, &ul->head);
1535 	spin_unlock_bh(&ul->lock);
1536 }
1537 
rt_del_uncached_list(struct rtable * rt)1538 void rt_del_uncached_list(struct rtable *rt)
1539 {
1540 	if (!list_empty(&rt->dst.rt_uncached)) {
1541 		struct uncached_list *ul = rt->dst.rt_uncached_list;
1542 
1543 		spin_lock_bh(&ul->lock);
1544 		list_del_init(&rt->dst.rt_uncached);
1545 		spin_unlock_bh(&ul->lock);
1546 	}
1547 }
1548 
ipv4_dst_destroy(struct dst_entry * dst)1549 static void ipv4_dst_destroy(struct dst_entry *dst)
1550 {
1551 	struct rtable *rt = (struct rtable *)dst;
1552 
1553 	ip_dst_metrics_put(dst);
1554 	rt_del_uncached_list(rt);
1555 }
1556 
rt_flush_dev(struct net_device * dev)1557 void rt_flush_dev(struct net_device *dev)
1558 {
1559 	struct rtable *rt, *safe;
1560 	int cpu;
1561 
1562 	for_each_possible_cpu(cpu) {
1563 		struct uncached_list *ul = &per_cpu(rt_uncached_list, cpu);
1564 
1565 		if (list_empty(&ul->head))
1566 			continue;
1567 
1568 		spin_lock_bh(&ul->lock);
1569 		list_for_each_entry_safe(rt, safe, &ul->head, dst.rt_uncached) {
1570 			if (rt->dst.dev != dev)
1571 				continue;
1572 			rt->dst.dev = blackhole_netdev;
1573 			netdev_ref_replace(dev, blackhole_netdev,
1574 					   &rt->dst.dev_tracker, GFP_ATOMIC);
1575 			list_move(&rt->dst.rt_uncached, &ul->quarantine);
1576 		}
1577 		spin_unlock_bh(&ul->lock);
1578 	}
1579 }
1580 
rt_cache_valid(const struct rtable * rt)1581 static bool rt_cache_valid(const struct rtable *rt)
1582 {
1583 	return	rt &&
1584 		rt->dst.obsolete == DST_OBSOLETE_FORCE_CHK &&
1585 		!rt_is_expired(rt);
1586 }
1587 
rt_set_nexthop(struct rtable * rt,__be32 daddr,const struct fib_result * res,struct fib_nh_exception * fnhe,struct fib_info * fi,u16 type,u32 itag,const bool do_cache)1588 static void rt_set_nexthop(struct rtable *rt, __be32 daddr,
1589 			   const struct fib_result *res,
1590 			   struct fib_nh_exception *fnhe,
1591 			   struct fib_info *fi, u16 type, u32 itag,
1592 			   const bool do_cache)
1593 {
1594 	bool cached = false;
1595 
1596 	if (fi) {
1597 		struct fib_nh_common *nhc = FIB_RES_NHC(*res);
1598 
1599 		if (nhc->nhc_gw_family && nhc->nhc_scope == RT_SCOPE_LINK) {
1600 			rt->rt_uses_gateway = 1;
1601 			rt->rt_gw_family = nhc->nhc_gw_family;
1602 			/* only INET and INET6 are supported */
1603 			if (likely(nhc->nhc_gw_family == AF_INET))
1604 				rt->rt_gw4 = nhc->nhc_gw.ipv4;
1605 			else
1606 				rt->rt_gw6 = nhc->nhc_gw.ipv6;
1607 		}
1608 
1609 		ip_dst_init_metrics(&rt->dst, fi->fib_metrics);
1610 
1611 #ifdef CONFIG_IP_ROUTE_CLASSID
1612 		if (nhc->nhc_family == AF_INET) {
1613 			struct fib_nh *nh;
1614 
1615 			nh = container_of(nhc, struct fib_nh, nh_common);
1616 			rt->dst.tclassid = nh->nh_tclassid;
1617 		}
1618 #endif
1619 		rt->dst.lwtstate = lwtstate_get(nhc->nhc_lwtstate);
1620 		if (unlikely(fnhe))
1621 			cached = rt_bind_exception(rt, fnhe, daddr, do_cache);
1622 		else if (do_cache)
1623 			cached = rt_cache_route(nhc, rt);
1624 		if (unlikely(!cached)) {
1625 			/* Routes we intend to cache in nexthop exception or
1626 			 * FIB nexthop have the DST_NOCACHE bit clear.
1627 			 * However, if we are unsuccessful at storing this
1628 			 * route into the cache we really need to set it.
1629 			 */
1630 			if (!rt->rt_gw4) {
1631 				rt->rt_gw_family = AF_INET;
1632 				rt->rt_gw4 = daddr;
1633 			}
1634 			rt_add_uncached_list(rt);
1635 		}
1636 	} else
1637 		rt_add_uncached_list(rt);
1638 
1639 #ifdef CONFIG_IP_ROUTE_CLASSID
1640 #ifdef CONFIG_IP_MULTIPLE_TABLES
1641 	set_class_tag(rt, res->tclassid);
1642 #endif
1643 	set_class_tag(rt, itag);
1644 #endif
1645 }
1646 
rt_dst_alloc(struct net_device * dev,unsigned int flags,u16 type,bool noxfrm)1647 struct rtable *rt_dst_alloc(struct net_device *dev,
1648 			    unsigned int flags, u16 type,
1649 			    bool noxfrm)
1650 {
1651 	struct rtable *rt;
1652 
1653 	rt = dst_alloc(&ipv4_dst_ops, dev, 1, DST_OBSOLETE_FORCE_CHK,
1654 		       (noxfrm ? DST_NOXFRM : 0));
1655 
1656 	if (rt) {
1657 		rt->rt_genid = rt_genid_ipv4(dev_net(dev));
1658 		rt->rt_flags = flags;
1659 		rt->rt_type = type;
1660 		rt->rt_is_input = 0;
1661 		rt->rt_iif = 0;
1662 		rt->rt_pmtu = 0;
1663 		rt->rt_mtu_locked = 0;
1664 		rt->rt_uses_gateway = 0;
1665 		rt->rt_gw_family = 0;
1666 		rt->rt_gw4 = 0;
1667 
1668 		rt->dst.output = ip_output;
1669 		if (flags & RTCF_LOCAL)
1670 			rt->dst.input = ip_local_deliver;
1671 	}
1672 
1673 	return rt;
1674 }
1675 EXPORT_SYMBOL(rt_dst_alloc);
1676 
rt_dst_clone(struct net_device * dev,struct rtable * rt)1677 struct rtable *rt_dst_clone(struct net_device *dev, struct rtable *rt)
1678 {
1679 	struct rtable *new_rt;
1680 
1681 	new_rt = dst_alloc(&ipv4_dst_ops, dev, 1, DST_OBSOLETE_FORCE_CHK,
1682 			   rt->dst.flags);
1683 
1684 	if (new_rt) {
1685 		new_rt->rt_genid = rt_genid_ipv4(dev_net(dev));
1686 		new_rt->rt_flags = rt->rt_flags;
1687 		new_rt->rt_type = rt->rt_type;
1688 		new_rt->rt_is_input = rt->rt_is_input;
1689 		new_rt->rt_iif = rt->rt_iif;
1690 		new_rt->rt_pmtu = rt->rt_pmtu;
1691 		new_rt->rt_mtu_locked = rt->rt_mtu_locked;
1692 		new_rt->rt_gw_family = rt->rt_gw_family;
1693 		if (rt->rt_gw_family == AF_INET)
1694 			new_rt->rt_gw4 = rt->rt_gw4;
1695 		else if (rt->rt_gw_family == AF_INET6)
1696 			new_rt->rt_gw6 = rt->rt_gw6;
1697 
1698 		new_rt->dst.input = rt->dst.input;
1699 		new_rt->dst.output = rt->dst.output;
1700 		new_rt->dst.error = rt->dst.error;
1701 		new_rt->dst.lastuse = jiffies;
1702 		new_rt->dst.lwtstate = lwtstate_get(rt->dst.lwtstate);
1703 	}
1704 	return new_rt;
1705 }
1706 EXPORT_SYMBOL(rt_dst_clone);
1707 
1708 /* called in rcu_read_lock() section */
ip_mc_validate_source(struct sk_buff * skb,__be32 daddr,__be32 saddr,u8 tos,struct net_device * dev,struct in_device * in_dev,u32 * itag)1709 int ip_mc_validate_source(struct sk_buff *skb, __be32 daddr, __be32 saddr,
1710 			  u8 tos, struct net_device *dev,
1711 			  struct in_device *in_dev, u32 *itag)
1712 {
1713 	int err;
1714 
1715 	/* Primary sanity checks. */
1716 	if (!in_dev)
1717 		return -EINVAL;
1718 
1719 	if (ipv4_is_multicast(saddr) || ipv4_is_lbcast(saddr) ||
1720 	    skb->protocol != htons(ETH_P_IP))
1721 		return -EINVAL;
1722 
1723 	if (ipv4_is_loopback(saddr) && !IN_DEV_ROUTE_LOCALNET(in_dev))
1724 		return -EINVAL;
1725 
1726 	if (ipv4_is_zeronet(saddr)) {
1727 		if (!ipv4_is_local_multicast(daddr) &&
1728 		    ip_hdr(skb)->protocol != IPPROTO_IGMP)
1729 			return -EINVAL;
1730 	} else {
1731 		err = fib_validate_source(skb, saddr, 0, tos, 0, dev,
1732 					  in_dev, itag);
1733 		if (err < 0)
1734 			return err;
1735 	}
1736 	return 0;
1737 }
1738 
1739 /* called in rcu_read_lock() section */
ip_route_input_mc(struct sk_buff * skb,__be32 daddr,__be32 saddr,u8 tos,struct net_device * dev,int our)1740 static int ip_route_input_mc(struct sk_buff *skb, __be32 daddr, __be32 saddr,
1741 			     u8 tos, struct net_device *dev, int our)
1742 {
1743 	struct in_device *in_dev = __in_dev_get_rcu(dev);
1744 	unsigned int flags = RTCF_MULTICAST;
1745 	struct rtable *rth;
1746 	u32 itag = 0;
1747 	int err;
1748 
1749 	err = ip_mc_validate_source(skb, daddr, saddr, tos, dev, in_dev, &itag);
1750 	if (err)
1751 		return err;
1752 
1753 	if (our)
1754 		flags |= RTCF_LOCAL;
1755 
1756 	if (IN_DEV_ORCONF(in_dev, NOPOLICY))
1757 		IPCB(skb)->flags |= IPSKB_NOPOLICY;
1758 
1759 	rth = rt_dst_alloc(dev_net(dev)->loopback_dev, flags, RTN_MULTICAST,
1760 			   false);
1761 	if (!rth)
1762 		return -ENOBUFS;
1763 
1764 #ifdef CONFIG_IP_ROUTE_CLASSID
1765 	rth->dst.tclassid = itag;
1766 #endif
1767 	rth->dst.output = ip_rt_bug;
1768 	rth->rt_is_input= 1;
1769 
1770 #ifdef CONFIG_IP_MROUTE
1771 	if (!ipv4_is_local_multicast(daddr) && IN_DEV_MFORWARD(in_dev))
1772 		rth->dst.input = ip_mr_input;
1773 #endif
1774 	RT_CACHE_STAT_INC(in_slow_mc);
1775 
1776 	skb_dst_drop(skb);
1777 	skb_dst_set(skb, &rth->dst);
1778 	return 0;
1779 }
1780 
1781 
ip_handle_martian_source(struct net_device * dev,struct in_device * in_dev,struct sk_buff * skb,__be32 daddr,__be32 saddr)1782 static void ip_handle_martian_source(struct net_device *dev,
1783 				     struct in_device *in_dev,
1784 				     struct sk_buff *skb,
1785 				     __be32 daddr,
1786 				     __be32 saddr)
1787 {
1788 	RT_CACHE_STAT_INC(in_martian_src);
1789 #ifdef CONFIG_IP_ROUTE_VERBOSE
1790 	if (IN_DEV_LOG_MARTIANS(in_dev) && net_ratelimit()) {
1791 		/*
1792 		 *	RFC1812 recommendation, if source is martian,
1793 		 *	the only hint is MAC header.
1794 		 */
1795 		pr_warn("martian source %pI4 from %pI4, on dev %s\n",
1796 			&daddr, &saddr, dev->name);
1797 		if (dev->hard_header_len && skb_mac_header_was_set(skb)) {
1798 			print_hex_dump(KERN_WARNING, "ll header: ",
1799 				       DUMP_PREFIX_OFFSET, 16, 1,
1800 				       skb_mac_header(skb),
1801 				       dev->hard_header_len, false);
1802 		}
1803 	}
1804 #endif
1805 }
1806 
1807 /* called in rcu_read_lock() section */
__mkroute_input(struct sk_buff * skb,const struct fib_result * res,struct in_device * in_dev,__be32 daddr,__be32 saddr,u32 tos)1808 static int __mkroute_input(struct sk_buff *skb,
1809 			   const struct fib_result *res,
1810 			   struct in_device *in_dev,
1811 			   __be32 daddr, __be32 saddr, u32 tos)
1812 {
1813 	struct fib_nh_common *nhc = FIB_RES_NHC(*res);
1814 	struct net_device *dev = nhc->nhc_dev;
1815 	struct fib_nh_exception *fnhe;
1816 	struct rtable *rth;
1817 	int err;
1818 	struct in_device *out_dev;
1819 	bool do_cache;
1820 	u32 itag = 0;
1821 
1822 	/* get a working reference to the output device */
1823 	out_dev = __in_dev_get_rcu(dev);
1824 	if (!out_dev) {
1825 		net_crit_ratelimited("Bug in ip_route_input_slow(). Please report.\n");
1826 		return -EINVAL;
1827 	}
1828 
1829 	err = fib_validate_source(skb, saddr, daddr, tos, FIB_RES_OIF(*res),
1830 				  in_dev->dev, in_dev, &itag);
1831 	if (err < 0) {
1832 		ip_handle_martian_source(in_dev->dev, in_dev, skb, daddr,
1833 					 saddr);
1834 
1835 		goto cleanup;
1836 	}
1837 
1838 	do_cache = res->fi && !itag;
1839 	if (out_dev == in_dev && err && IN_DEV_TX_REDIRECTS(out_dev) &&
1840 	    skb->protocol == htons(ETH_P_IP)) {
1841 		__be32 gw;
1842 
1843 		gw = nhc->nhc_gw_family == AF_INET ? nhc->nhc_gw.ipv4 : 0;
1844 		if (IN_DEV_SHARED_MEDIA(out_dev) ||
1845 		    inet_addr_onlink(out_dev, saddr, gw))
1846 			IPCB(skb)->flags |= IPSKB_DOREDIRECT;
1847 	}
1848 
1849 	if (skb->protocol != htons(ETH_P_IP)) {
1850 		/* Not IP (i.e. ARP). Do not create route, if it is
1851 		 * invalid for proxy arp. DNAT routes are always valid.
1852 		 *
1853 		 * Proxy arp feature have been extended to allow, ARP
1854 		 * replies back to the same interface, to support
1855 		 * Private VLAN switch technologies. See arp.c.
1856 		 */
1857 		if (out_dev == in_dev &&
1858 		    IN_DEV_PROXY_ARP_PVLAN(in_dev) == 0) {
1859 			err = -EINVAL;
1860 			goto cleanup;
1861 		}
1862 	}
1863 
1864 	if (IN_DEV_ORCONF(in_dev, NOPOLICY))
1865 		IPCB(skb)->flags |= IPSKB_NOPOLICY;
1866 
1867 	fnhe = find_exception(nhc, daddr);
1868 	if (do_cache) {
1869 		if (fnhe)
1870 			rth = rcu_dereference(fnhe->fnhe_rth_input);
1871 		else
1872 			rth = rcu_dereference(nhc->nhc_rth_input);
1873 		if (rt_cache_valid(rth)) {
1874 			skb_dst_set_noref(skb, &rth->dst);
1875 			goto out;
1876 		}
1877 	}
1878 
1879 	rth = rt_dst_alloc(out_dev->dev, 0, res->type,
1880 			   IN_DEV_ORCONF(out_dev, NOXFRM));
1881 	if (!rth) {
1882 		err = -ENOBUFS;
1883 		goto cleanup;
1884 	}
1885 
1886 	rth->rt_is_input = 1;
1887 	RT_CACHE_STAT_INC(in_slow_tot);
1888 
1889 	rth->dst.input = ip_forward;
1890 
1891 	rt_set_nexthop(rth, daddr, res, fnhe, res->fi, res->type, itag,
1892 		       do_cache);
1893 	lwtunnel_set_redirect(&rth->dst);
1894 	skb_dst_set(skb, &rth->dst);
1895 out:
1896 	err = 0;
1897  cleanup:
1898 	return err;
1899 }
1900 
1901 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1902 /* To make ICMP packets follow the right flow, the multipath hash is
1903  * calculated from the inner IP addresses.
1904  */
ip_multipath_l3_keys(const struct sk_buff * skb,struct flow_keys * hash_keys)1905 static void ip_multipath_l3_keys(const struct sk_buff *skb,
1906 				 struct flow_keys *hash_keys)
1907 {
1908 	const struct iphdr *outer_iph = ip_hdr(skb);
1909 	const struct iphdr *key_iph = outer_iph;
1910 	const struct iphdr *inner_iph;
1911 	const struct icmphdr *icmph;
1912 	struct iphdr _inner_iph;
1913 	struct icmphdr _icmph;
1914 
1915 	if (likely(outer_iph->protocol != IPPROTO_ICMP))
1916 		goto out;
1917 
1918 	if (unlikely((outer_iph->frag_off & htons(IP_OFFSET)) != 0))
1919 		goto out;
1920 
1921 	icmph = skb_header_pointer(skb, outer_iph->ihl * 4, sizeof(_icmph),
1922 				   &_icmph);
1923 	if (!icmph)
1924 		goto out;
1925 
1926 	if (!icmp_is_err(icmph->type))
1927 		goto out;
1928 
1929 	inner_iph = skb_header_pointer(skb,
1930 				       outer_iph->ihl * 4 + sizeof(_icmph),
1931 				       sizeof(_inner_iph), &_inner_iph);
1932 	if (!inner_iph)
1933 		goto out;
1934 
1935 	key_iph = inner_iph;
1936 out:
1937 	hash_keys->addrs.v4addrs.src = key_iph->saddr;
1938 	hash_keys->addrs.v4addrs.dst = key_iph->daddr;
1939 }
1940 
fib_multipath_custom_hash_outer(const struct net * net,const struct sk_buff * skb,bool * p_has_inner)1941 static u32 fib_multipath_custom_hash_outer(const struct net *net,
1942 					   const struct sk_buff *skb,
1943 					   bool *p_has_inner)
1944 {
1945 	u32 hash_fields = READ_ONCE(net->ipv4.sysctl_fib_multipath_hash_fields);
1946 	struct flow_keys keys, hash_keys;
1947 
1948 	if (!(hash_fields & FIB_MULTIPATH_HASH_FIELD_OUTER_MASK))
1949 		return 0;
1950 
1951 	memset(&hash_keys, 0, sizeof(hash_keys));
1952 	skb_flow_dissect_flow_keys(skb, &keys, FLOW_DISSECTOR_F_STOP_AT_ENCAP);
1953 
1954 	hash_keys.control.addr_type = FLOW_DISSECTOR_KEY_IPV4_ADDRS;
1955 	if (hash_fields & FIB_MULTIPATH_HASH_FIELD_SRC_IP)
1956 		hash_keys.addrs.v4addrs.src = keys.addrs.v4addrs.src;
1957 	if (hash_fields & FIB_MULTIPATH_HASH_FIELD_DST_IP)
1958 		hash_keys.addrs.v4addrs.dst = keys.addrs.v4addrs.dst;
1959 	if (hash_fields & FIB_MULTIPATH_HASH_FIELD_IP_PROTO)
1960 		hash_keys.basic.ip_proto = keys.basic.ip_proto;
1961 	if (hash_fields & FIB_MULTIPATH_HASH_FIELD_SRC_PORT)
1962 		hash_keys.ports.src = keys.ports.src;
1963 	if (hash_fields & FIB_MULTIPATH_HASH_FIELD_DST_PORT)
1964 		hash_keys.ports.dst = keys.ports.dst;
1965 
1966 	*p_has_inner = !!(keys.control.flags & FLOW_DIS_ENCAPSULATION);
1967 	return flow_hash_from_keys(&hash_keys);
1968 }
1969 
fib_multipath_custom_hash_inner(const struct net * net,const struct sk_buff * skb,bool has_inner)1970 static u32 fib_multipath_custom_hash_inner(const struct net *net,
1971 					   const struct sk_buff *skb,
1972 					   bool has_inner)
1973 {
1974 	u32 hash_fields = READ_ONCE(net->ipv4.sysctl_fib_multipath_hash_fields);
1975 	struct flow_keys keys, hash_keys;
1976 
1977 	/* We assume the packet carries an encapsulation, but if none was
1978 	 * encountered during dissection of the outer flow, then there is no
1979 	 * point in calling the flow dissector again.
1980 	 */
1981 	if (!has_inner)
1982 		return 0;
1983 
1984 	if (!(hash_fields & FIB_MULTIPATH_HASH_FIELD_INNER_MASK))
1985 		return 0;
1986 
1987 	memset(&hash_keys, 0, sizeof(hash_keys));
1988 	skb_flow_dissect_flow_keys(skb, &keys, 0);
1989 
1990 	if (!(keys.control.flags & FLOW_DIS_ENCAPSULATION))
1991 		return 0;
1992 
1993 	if (keys.control.addr_type == FLOW_DISSECTOR_KEY_IPV4_ADDRS) {
1994 		hash_keys.control.addr_type = FLOW_DISSECTOR_KEY_IPV4_ADDRS;
1995 		if (hash_fields & FIB_MULTIPATH_HASH_FIELD_INNER_SRC_IP)
1996 			hash_keys.addrs.v4addrs.src = keys.addrs.v4addrs.src;
1997 		if (hash_fields & FIB_MULTIPATH_HASH_FIELD_INNER_DST_IP)
1998 			hash_keys.addrs.v4addrs.dst = keys.addrs.v4addrs.dst;
1999 	} else if (keys.control.addr_type == FLOW_DISSECTOR_KEY_IPV6_ADDRS) {
2000 		hash_keys.control.addr_type = FLOW_DISSECTOR_KEY_IPV6_ADDRS;
2001 		if (hash_fields & FIB_MULTIPATH_HASH_FIELD_INNER_SRC_IP)
2002 			hash_keys.addrs.v6addrs.src = keys.addrs.v6addrs.src;
2003 		if (hash_fields & FIB_MULTIPATH_HASH_FIELD_INNER_DST_IP)
2004 			hash_keys.addrs.v6addrs.dst = keys.addrs.v6addrs.dst;
2005 		if (hash_fields & FIB_MULTIPATH_HASH_FIELD_INNER_FLOWLABEL)
2006 			hash_keys.tags.flow_label = keys.tags.flow_label;
2007 	}
2008 
2009 	if (hash_fields & FIB_MULTIPATH_HASH_FIELD_INNER_IP_PROTO)
2010 		hash_keys.basic.ip_proto = keys.basic.ip_proto;
2011 	if (hash_fields & FIB_MULTIPATH_HASH_FIELD_INNER_SRC_PORT)
2012 		hash_keys.ports.src = keys.ports.src;
2013 	if (hash_fields & FIB_MULTIPATH_HASH_FIELD_INNER_DST_PORT)
2014 		hash_keys.ports.dst = keys.ports.dst;
2015 
2016 	return flow_hash_from_keys(&hash_keys);
2017 }
2018 
fib_multipath_custom_hash_skb(const struct net * net,const struct sk_buff * skb)2019 static u32 fib_multipath_custom_hash_skb(const struct net *net,
2020 					 const struct sk_buff *skb)
2021 {
2022 	u32 mhash, mhash_inner;
2023 	bool has_inner = true;
2024 
2025 	mhash = fib_multipath_custom_hash_outer(net, skb, &has_inner);
2026 	mhash_inner = fib_multipath_custom_hash_inner(net, skb, has_inner);
2027 
2028 	return jhash_2words(mhash, mhash_inner, 0);
2029 }
2030 
fib_multipath_custom_hash_fl4(const struct net * net,const struct flowi4 * fl4)2031 static u32 fib_multipath_custom_hash_fl4(const struct net *net,
2032 					 const struct flowi4 *fl4)
2033 {
2034 	u32 hash_fields = READ_ONCE(net->ipv4.sysctl_fib_multipath_hash_fields);
2035 	struct flow_keys hash_keys;
2036 
2037 	if (!(hash_fields & FIB_MULTIPATH_HASH_FIELD_OUTER_MASK))
2038 		return 0;
2039 
2040 	memset(&hash_keys, 0, sizeof(hash_keys));
2041 	hash_keys.control.addr_type = FLOW_DISSECTOR_KEY_IPV4_ADDRS;
2042 	if (hash_fields & FIB_MULTIPATH_HASH_FIELD_SRC_IP)
2043 		hash_keys.addrs.v4addrs.src = fl4->saddr;
2044 	if (hash_fields & FIB_MULTIPATH_HASH_FIELD_DST_IP)
2045 		hash_keys.addrs.v4addrs.dst = fl4->daddr;
2046 	if (hash_fields & FIB_MULTIPATH_HASH_FIELD_IP_PROTO)
2047 		hash_keys.basic.ip_proto = fl4->flowi4_proto;
2048 	if (hash_fields & FIB_MULTIPATH_HASH_FIELD_SRC_PORT)
2049 		hash_keys.ports.src = fl4->fl4_sport;
2050 	if (hash_fields & FIB_MULTIPATH_HASH_FIELD_DST_PORT)
2051 		hash_keys.ports.dst = fl4->fl4_dport;
2052 
2053 	return flow_hash_from_keys(&hash_keys);
2054 }
2055 
2056 /* if skb is set it will be used and fl4 can be NULL */
fib_multipath_hash(const struct net * net,const struct flowi4 * fl4,const struct sk_buff * skb,struct flow_keys * flkeys)2057 int fib_multipath_hash(const struct net *net, const struct flowi4 *fl4,
2058 		       const struct sk_buff *skb, struct flow_keys *flkeys)
2059 {
2060 	u32 multipath_hash = fl4 ? fl4->flowi4_multipath_hash : 0;
2061 	struct flow_keys hash_keys;
2062 	u32 mhash = 0;
2063 
2064 	switch (READ_ONCE(net->ipv4.sysctl_fib_multipath_hash_policy)) {
2065 	case 0:
2066 		memset(&hash_keys, 0, sizeof(hash_keys));
2067 		hash_keys.control.addr_type = FLOW_DISSECTOR_KEY_IPV4_ADDRS;
2068 		if (skb) {
2069 			ip_multipath_l3_keys(skb, &hash_keys);
2070 		} else {
2071 			hash_keys.addrs.v4addrs.src = fl4->saddr;
2072 			hash_keys.addrs.v4addrs.dst = fl4->daddr;
2073 		}
2074 		mhash = flow_hash_from_keys(&hash_keys);
2075 		break;
2076 	case 1:
2077 		/* skb is currently provided only when forwarding */
2078 		if (skb) {
2079 			unsigned int flag = FLOW_DISSECTOR_F_STOP_AT_ENCAP;
2080 			struct flow_keys keys;
2081 
2082 			/* short-circuit if we already have L4 hash present */
2083 			if (skb->l4_hash)
2084 				return skb_get_hash_raw(skb) >> 1;
2085 
2086 			memset(&hash_keys, 0, sizeof(hash_keys));
2087 
2088 			if (!flkeys) {
2089 				skb_flow_dissect_flow_keys(skb, &keys, flag);
2090 				flkeys = &keys;
2091 			}
2092 
2093 			hash_keys.control.addr_type = FLOW_DISSECTOR_KEY_IPV4_ADDRS;
2094 			hash_keys.addrs.v4addrs.src = flkeys->addrs.v4addrs.src;
2095 			hash_keys.addrs.v4addrs.dst = flkeys->addrs.v4addrs.dst;
2096 			hash_keys.ports.src = flkeys->ports.src;
2097 			hash_keys.ports.dst = flkeys->ports.dst;
2098 			hash_keys.basic.ip_proto = flkeys->basic.ip_proto;
2099 		} else {
2100 			memset(&hash_keys, 0, sizeof(hash_keys));
2101 			hash_keys.control.addr_type = FLOW_DISSECTOR_KEY_IPV4_ADDRS;
2102 			hash_keys.addrs.v4addrs.src = fl4->saddr;
2103 			hash_keys.addrs.v4addrs.dst = fl4->daddr;
2104 			hash_keys.ports.src = fl4->fl4_sport;
2105 			hash_keys.ports.dst = fl4->fl4_dport;
2106 			hash_keys.basic.ip_proto = fl4->flowi4_proto;
2107 		}
2108 		mhash = flow_hash_from_keys(&hash_keys);
2109 		break;
2110 	case 2:
2111 		memset(&hash_keys, 0, sizeof(hash_keys));
2112 		/* skb is currently provided only when forwarding */
2113 		if (skb) {
2114 			struct flow_keys keys;
2115 
2116 			skb_flow_dissect_flow_keys(skb, &keys, 0);
2117 			/* Inner can be v4 or v6 */
2118 			if (keys.control.addr_type == FLOW_DISSECTOR_KEY_IPV4_ADDRS) {
2119 				hash_keys.control.addr_type = FLOW_DISSECTOR_KEY_IPV4_ADDRS;
2120 				hash_keys.addrs.v4addrs.src = keys.addrs.v4addrs.src;
2121 				hash_keys.addrs.v4addrs.dst = keys.addrs.v4addrs.dst;
2122 			} else if (keys.control.addr_type == FLOW_DISSECTOR_KEY_IPV6_ADDRS) {
2123 				hash_keys.control.addr_type = FLOW_DISSECTOR_KEY_IPV6_ADDRS;
2124 				hash_keys.addrs.v6addrs.src = keys.addrs.v6addrs.src;
2125 				hash_keys.addrs.v6addrs.dst = keys.addrs.v6addrs.dst;
2126 				hash_keys.tags.flow_label = keys.tags.flow_label;
2127 				hash_keys.basic.ip_proto = keys.basic.ip_proto;
2128 			} else {
2129 				/* Same as case 0 */
2130 				hash_keys.control.addr_type = FLOW_DISSECTOR_KEY_IPV4_ADDRS;
2131 				ip_multipath_l3_keys(skb, &hash_keys);
2132 			}
2133 		} else {
2134 			/* Same as case 0 */
2135 			hash_keys.control.addr_type = FLOW_DISSECTOR_KEY_IPV4_ADDRS;
2136 			hash_keys.addrs.v4addrs.src = fl4->saddr;
2137 			hash_keys.addrs.v4addrs.dst = fl4->daddr;
2138 		}
2139 		mhash = flow_hash_from_keys(&hash_keys);
2140 		break;
2141 	case 3:
2142 		if (skb)
2143 			mhash = fib_multipath_custom_hash_skb(net, skb);
2144 		else
2145 			mhash = fib_multipath_custom_hash_fl4(net, fl4);
2146 		break;
2147 	}
2148 
2149 	if (multipath_hash)
2150 		mhash = jhash_2words(mhash, multipath_hash, 0);
2151 
2152 	return mhash >> 1;
2153 }
2154 #endif /* CONFIG_IP_ROUTE_MULTIPATH */
2155 
ip_mkroute_input(struct sk_buff * skb,struct fib_result * res,struct in_device * in_dev,__be32 daddr,__be32 saddr,u32 tos,struct flow_keys * hkeys)2156 static int ip_mkroute_input(struct sk_buff *skb,
2157 			    struct fib_result *res,
2158 			    struct in_device *in_dev,
2159 			    __be32 daddr, __be32 saddr, u32 tos,
2160 			    struct flow_keys *hkeys)
2161 {
2162 #ifdef CONFIG_IP_ROUTE_MULTIPATH
2163 	if (res->fi && fib_info_num_path(res->fi) > 1) {
2164 		int h = fib_multipath_hash(res->fi->fib_net, NULL, skb, hkeys);
2165 
2166 		fib_select_multipath(res, h);
2167 		IPCB(skb)->flags |= IPSKB_MULTIPATH;
2168 	}
2169 #endif
2170 
2171 	/* create a routing cache entry */
2172 	return __mkroute_input(skb, res, in_dev, daddr, saddr, tos);
2173 }
2174 
2175 /* Implements all the saddr-related checks as ip_route_input_slow(),
2176  * assuming daddr is valid and the destination is not a local broadcast one.
2177  * Uses the provided hint instead of performing a route lookup.
2178  */
ip_route_use_hint(struct sk_buff * skb,__be32 daddr,__be32 saddr,u8 tos,struct net_device * dev,const struct sk_buff * hint)2179 int ip_route_use_hint(struct sk_buff *skb, __be32 daddr, __be32 saddr,
2180 		      u8 tos, struct net_device *dev,
2181 		      const struct sk_buff *hint)
2182 {
2183 	struct in_device *in_dev = __in_dev_get_rcu(dev);
2184 	struct rtable *rt = skb_rtable(hint);
2185 	struct net *net = dev_net(dev);
2186 	int err = -EINVAL;
2187 	u32 tag = 0;
2188 
2189 	if (!in_dev)
2190 		return -EINVAL;
2191 
2192 	if (ipv4_is_multicast(saddr) || ipv4_is_lbcast(saddr))
2193 		goto martian_source;
2194 
2195 	if (ipv4_is_zeronet(saddr))
2196 		goto martian_source;
2197 
2198 	if (ipv4_is_loopback(saddr) && !IN_DEV_NET_ROUTE_LOCALNET(in_dev, net))
2199 		goto martian_source;
2200 
2201 	if (rt->rt_type != RTN_LOCAL)
2202 		goto skip_validate_source;
2203 
2204 	tos &= IPTOS_RT_MASK;
2205 	err = fib_validate_source(skb, saddr, daddr, tos, 0, dev, in_dev, &tag);
2206 	if (err < 0)
2207 		goto martian_source;
2208 
2209 skip_validate_source:
2210 	skb_dst_copy(skb, hint);
2211 	return 0;
2212 
2213 martian_source:
2214 	ip_handle_martian_source(dev, in_dev, skb, daddr, saddr);
2215 	return err;
2216 }
2217 
2218 /* get device for dst_alloc with local routes */
ip_rt_get_dev(struct net * net,const struct fib_result * res)2219 static struct net_device *ip_rt_get_dev(struct net *net,
2220 					const struct fib_result *res)
2221 {
2222 	struct fib_nh_common *nhc = res->fi ? res->nhc : NULL;
2223 	struct net_device *dev = NULL;
2224 
2225 	if (nhc)
2226 		dev = l3mdev_master_dev_rcu(nhc->nhc_dev);
2227 
2228 	return dev ? : net->loopback_dev;
2229 }
2230 
2231 /*
2232  *	NOTE. We drop all the packets that has local source
2233  *	addresses, because every properly looped back packet
2234  *	must have correct destination already attached by output routine.
2235  *	Changes in the enforced policies must be applied also to
2236  *	ip_route_use_hint().
2237  *
2238  *	Such approach solves two big problems:
2239  *	1. Not simplex devices are handled properly.
2240  *	2. IP spoofing attempts are filtered with 100% of guarantee.
2241  *	called with rcu_read_lock()
2242  */
2243 
ip_route_input_slow(struct sk_buff * skb,__be32 daddr,__be32 saddr,u8 tos,struct net_device * dev,struct fib_result * res)2244 static int ip_route_input_slow(struct sk_buff *skb, __be32 daddr, __be32 saddr,
2245 			       u8 tos, struct net_device *dev,
2246 			       struct fib_result *res)
2247 {
2248 	struct in_device *in_dev = __in_dev_get_rcu(dev);
2249 	struct flow_keys *flkeys = NULL, _flkeys;
2250 	struct net    *net = dev_net(dev);
2251 	struct ip_tunnel_info *tun_info;
2252 	int		err = -EINVAL;
2253 	unsigned int	flags = 0;
2254 	u32		itag = 0;
2255 	struct rtable	*rth;
2256 	struct flowi4	fl4;
2257 	bool do_cache = true;
2258 
2259 	/* IP on this device is disabled. */
2260 
2261 	if (!in_dev)
2262 		goto out;
2263 
2264 	/* Check for the most weird martians, which can be not detected
2265 	 * by fib_lookup.
2266 	 */
2267 
2268 	tun_info = skb_tunnel_info(skb);
2269 	if (tun_info && !(tun_info->mode & IP_TUNNEL_INFO_TX))
2270 		fl4.flowi4_tun_key.tun_id = tun_info->key.tun_id;
2271 	else
2272 		fl4.flowi4_tun_key.tun_id = 0;
2273 	skb_dst_drop(skb);
2274 
2275 	if (ipv4_is_multicast(saddr) || ipv4_is_lbcast(saddr))
2276 		goto martian_source;
2277 
2278 	res->fi = NULL;
2279 	res->table = NULL;
2280 	if (ipv4_is_lbcast(daddr) || (saddr == 0 && daddr == 0))
2281 		goto brd_input;
2282 
2283 	/* Accept zero addresses only to limited broadcast;
2284 	 * I even do not know to fix it or not. Waiting for complains :-)
2285 	 */
2286 	if (ipv4_is_zeronet(saddr))
2287 		goto martian_source;
2288 
2289 	if (ipv4_is_zeronet(daddr))
2290 		goto martian_destination;
2291 
2292 	/* Following code try to avoid calling IN_DEV_NET_ROUTE_LOCALNET(),
2293 	 * and call it once if daddr or/and saddr are loopback addresses
2294 	 */
2295 	if (ipv4_is_loopback(daddr)) {
2296 		if (!IN_DEV_NET_ROUTE_LOCALNET(in_dev, net))
2297 			goto martian_destination;
2298 	} else if (ipv4_is_loopback(saddr)) {
2299 		if (!IN_DEV_NET_ROUTE_LOCALNET(in_dev, net))
2300 			goto martian_source;
2301 	}
2302 
2303 	/*
2304 	 *	Now we are ready to route packet.
2305 	 */
2306 	fl4.flowi4_l3mdev = 0;
2307 	fl4.flowi4_oif = 0;
2308 	fl4.flowi4_iif = dev->ifindex;
2309 	fl4.flowi4_mark = skb->mark;
2310 	fl4.flowi4_tos = tos;
2311 	fl4.flowi4_scope = RT_SCOPE_UNIVERSE;
2312 	fl4.flowi4_flags = 0;
2313 	fl4.daddr = daddr;
2314 	fl4.saddr = saddr;
2315 	fl4.flowi4_uid = sock_net_uid(net, NULL);
2316 	fl4.flowi4_multipath_hash = 0;
2317 
2318 	if (fib4_rules_early_flow_dissect(net, skb, &fl4, &_flkeys)) {
2319 		flkeys = &_flkeys;
2320 	} else {
2321 		fl4.flowi4_proto = 0;
2322 		fl4.fl4_sport = 0;
2323 		fl4.fl4_dport = 0;
2324 	}
2325 
2326 	err = fib_lookup(net, &fl4, res, 0);
2327 	if (err != 0) {
2328 		if (!IN_DEV_FORWARD(in_dev))
2329 			err = -EHOSTUNREACH;
2330 		goto no_route;
2331 	}
2332 
2333 	if (res->type == RTN_BROADCAST) {
2334 		if (IN_DEV_BFORWARD(in_dev))
2335 			goto make_route;
2336 		/* not do cache if bc_forwarding is enabled */
2337 		if (IPV4_DEVCONF_ALL(net, BC_FORWARDING))
2338 			do_cache = false;
2339 		goto brd_input;
2340 	}
2341 
2342 	if (res->type == RTN_LOCAL) {
2343 		err = fib_validate_source(skb, saddr, daddr, tos,
2344 					  0, dev, in_dev, &itag);
2345 		if (err < 0)
2346 			goto martian_source;
2347 		goto local_input;
2348 	}
2349 
2350 	if (!IN_DEV_FORWARD(in_dev)) {
2351 		err = -EHOSTUNREACH;
2352 		goto no_route;
2353 	}
2354 	if (res->type != RTN_UNICAST)
2355 		goto martian_destination;
2356 
2357 make_route:
2358 	err = ip_mkroute_input(skb, res, in_dev, daddr, saddr, tos, flkeys);
2359 out:	return err;
2360 
2361 brd_input:
2362 	if (skb->protocol != htons(ETH_P_IP))
2363 		goto e_inval;
2364 
2365 	if (!ipv4_is_zeronet(saddr)) {
2366 		err = fib_validate_source(skb, saddr, 0, tos, 0, dev,
2367 					  in_dev, &itag);
2368 		if (err < 0)
2369 			goto martian_source;
2370 	}
2371 	flags |= RTCF_BROADCAST;
2372 	res->type = RTN_BROADCAST;
2373 	RT_CACHE_STAT_INC(in_brd);
2374 
2375 local_input:
2376 	if (IN_DEV_ORCONF(in_dev, NOPOLICY))
2377 		IPCB(skb)->flags |= IPSKB_NOPOLICY;
2378 
2379 	do_cache &= res->fi && !itag;
2380 	if (do_cache) {
2381 		struct fib_nh_common *nhc = FIB_RES_NHC(*res);
2382 
2383 		rth = rcu_dereference(nhc->nhc_rth_input);
2384 		if (rt_cache_valid(rth)) {
2385 			skb_dst_set_noref(skb, &rth->dst);
2386 			err = 0;
2387 			goto out;
2388 		}
2389 	}
2390 
2391 	rth = rt_dst_alloc(ip_rt_get_dev(net, res),
2392 			   flags | RTCF_LOCAL, res->type, false);
2393 	if (!rth)
2394 		goto e_nobufs;
2395 
2396 	rth->dst.output= ip_rt_bug;
2397 #ifdef CONFIG_IP_ROUTE_CLASSID
2398 	rth->dst.tclassid = itag;
2399 #endif
2400 	rth->rt_is_input = 1;
2401 
2402 	RT_CACHE_STAT_INC(in_slow_tot);
2403 	if (res->type == RTN_UNREACHABLE) {
2404 		rth->dst.input= ip_error;
2405 		rth->dst.error= -err;
2406 		rth->rt_flags	&= ~RTCF_LOCAL;
2407 	}
2408 
2409 	if (do_cache) {
2410 		struct fib_nh_common *nhc = FIB_RES_NHC(*res);
2411 
2412 		rth->dst.lwtstate = lwtstate_get(nhc->nhc_lwtstate);
2413 		if (lwtunnel_input_redirect(rth->dst.lwtstate)) {
2414 			WARN_ON(rth->dst.input == lwtunnel_input);
2415 			rth->dst.lwtstate->orig_input = rth->dst.input;
2416 			rth->dst.input = lwtunnel_input;
2417 		}
2418 
2419 		if (unlikely(!rt_cache_route(nhc, rth)))
2420 			rt_add_uncached_list(rth);
2421 	}
2422 	skb_dst_set(skb, &rth->dst);
2423 	err = 0;
2424 	goto out;
2425 
2426 no_route:
2427 	RT_CACHE_STAT_INC(in_no_route);
2428 	res->type = RTN_UNREACHABLE;
2429 	res->fi = NULL;
2430 	res->table = NULL;
2431 	goto local_input;
2432 
2433 	/*
2434 	 *	Do not cache martian addresses: they should be logged (RFC1812)
2435 	 */
2436 martian_destination:
2437 	RT_CACHE_STAT_INC(in_martian_dst);
2438 #ifdef CONFIG_IP_ROUTE_VERBOSE
2439 	if (IN_DEV_LOG_MARTIANS(in_dev))
2440 		net_warn_ratelimited("martian destination %pI4 from %pI4, dev %s\n",
2441 				     &daddr, &saddr, dev->name);
2442 #endif
2443 
2444 e_inval:
2445 	err = -EINVAL;
2446 	goto out;
2447 
2448 e_nobufs:
2449 	err = -ENOBUFS;
2450 	goto out;
2451 
2452 martian_source:
2453 	ip_handle_martian_source(dev, in_dev, skb, daddr, saddr);
2454 	goto out;
2455 }
2456 
2457 /* called with rcu_read_lock held */
ip_route_input_rcu(struct sk_buff * skb,__be32 daddr,__be32 saddr,u8 tos,struct net_device * dev,struct fib_result * res)2458 static int ip_route_input_rcu(struct sk_buff *skb, __be32 daddr, __be32 saddr,
2459 			      u8 tos, struct net_device *dev, struct fib_result *res)
2460 {
2461 	/* Multicast recognition logic is moved from route cache to here.
2462 	 * The problem was that too many Ethernet cards have broken/missing
2463 	 * hardware multicast filters :-( As result the host on multicasting
2464 	 * network acquires a lot of useless route cache entries, sort of
2465 	 * SDR messages from all the world. Now we try to get rid of them.
2466 	 * Really, provided software IP multicast filter is organized
2467 	 * reasonably (at least, hashed), it does not result in a slowdown
2468 	 * comparing with route cache reject entries.
2469 	 * Note, that multicast routers are not affected, because
2470 	 * route cache entry is created eventually.
2471 	 */
2472 	if (ipv4_is_multicast(daddr)) {
2473 		struct in_device *in_dev = __in_dev_get_rcu(dev);
2474 		int our = 0;
2475 		int err = -EINVAL;
2476 
2477 		if (!in_dev)
2478 			return err;
2479 		our = ip_check_mc_rcu(in_dev, daddr, saddr,
2480 				      ip_hdr(skb)->protocol);
2481 
2482 		/* check l3 master if no match yet */
2483 		if (!our && netif_is_l3_slave(dev)) {
2484 			struct in_device *l3_in_dev;
2485 
2486 			l3_in_dev = __in_dev_get_rcu(skb->dev);
2487 			if (l3_in_dev)
2488 				our = ip_check_mc_rcu(l3_in_dev, daddr, saddr,
2489 						      ip_hdr(skb)->protocol);
2490 		}
2491 
2492 		if (our
2493 #ifdef CONFIG_IP_MROUTE
2494 			||
2495 		    (!ipv4_is_local_multicast(daddr) &&
2496 		     IN_DEV_MFORWARD(in_dev))
2497 #endif
2498 		   ) {
2499 			err = ip_route_input_mc(skb, daddr, saddr,
2500 						tos, dev, our);
2501 		}
2502 		return err;
2503 	}
2504 
2505 	return ip_route_input_slow(skb, daddr, saddr, tos, dev, res);
2506 }
2507 
ip_route_input_noref(struct sk_buff * skb,__be32 daddr,__be32 saddr,u8 tos,struct net_device * dev)2508 int ip_route_input_noref(struct sk_buff *skb, __be32 daddr, __be32 saddr,
2509 			 u8 tos, struct net_device *dev)
2510 {
2511 	struct fib_result res;
2512 	int err;
2513 
2514 	tos &= IPTOS_RT_MASK;
2515 	rcu_read_lock();
2516 	err = ip_route_input_rcu(skb, daddr, saddr, tos, dev, &res);
2517 	rcu_read_unlock();
2518 
2519 	return err;
2520 }
2521 EXPORT_SYMBOL(ip_route_input_noref);
2522 
2523 /* called with rcu_read_lock() */
__mkroute_output(const struct fib_result * res,const struct flowi4 * fl4,int orig_oif,struct net_device * dev_out,unsigned int flags)2524 static struct rtable *__mkroute_output(const struct fib_result *res,
2525 				       const struct flowi4 *fl4, int orig_oif,
2526 				       struct net_device *dev_out,
2527 				       unsigned int flags)
2528 {
2529 	struct fib_info *fi = res->fi;
2530 	struct fib_nh_exception *fnhe;
2531 	struct in_device *in_dev;
2532 	u16 type = res->type;
2533 	struct rtable *rth;
2534 	bool do_cache;
2535 
2536 	in_dev = __in_dev_get_rcu(dev_out);
2537 	if (!in_dev)
2538 		return ERR_PTR(-EINVAL);
2539 
2540 	if (likely(!IN_DEV_ROUTE_LOCALNET(in_dev)))
2541 		if (ipv4_is_loopback(fl4->saddr) &&
2542 		    !(dev_out->flags & IFF_LOOPBACK) &&
2543 		    !netif_is_l3_master(dev_out))
2544 			return ERR_PTR(-EINVAL);
2545 
2546 	if (ipv4_is_lbcast(fl4->daddr))
2547 		type = RTN_BROADCAST;
2548 	else if (ipv4_is_multicast(fl4->daddr))
2549 		type = RTN_MULTICAST;
2550 	else if (ipv4_is_zeronet(fl4->daddr))
2551 		return ERR_PTR(-EINVAL);
2552 
2553 	if (dev_out->flags & IFF_LOOPBACK)
2554 		flags |= RTCF_LOCAL;
2555 
2556 	do_cache = true;
2557 	if (type == RTN_BROADCAST) {
2558 		flags |= RTCF_BROADCAST | RTCF_LOCAL;
2559 		fi = NULL;
2560 	} else if (type == RTN_MULTICAST) {
2561 		flags |= RTCF_MULTICAST | RTCF_LOCAL;
2562 		if (!ip_check_mc_rcu(in_dev, fl4->daddr, fl4->saddr,
2563 				     fl4->flowi4_proto))
2564 			flags &= ~RTCF_LOCAL;
2565 		else
2566 			do_cache = false;
2567 		/* If multicast route do not exist use
2568 		 * default one, but do not gateway in this case.
2569 		 * Yes, it is hack.
2570 		 */
2571 		if (fi && res->prefixlen < 4)
2572 			fi = NULL;
2573 	} else if ((type == RTN_LOCAL) && (orig_oif != 0) &&
2574 		   (orig_oif != dev_out->ifindex)) {
2575 		/* For local routes that require a particular output interface
2576 		 * we do not want to cache the result.  Caching the result
2577 		 * causes incorrect behaviour when there are multiple source
2578 		 * addresses on the interface, the end result being that if the
2579 		 * intended recipient is waiting on that interface for the
2580 		 * packet he won't receive it because it will be delivered on
2581 		 * the loopback interface and the IP_PKTINFO ipi_ifindex will
2582 		 * be set to the loopback interface as well.
2583 		 */
2584 		do_cache = false;
2585 	}
2586 
2587 	fnhe = NULL;
2588 	do_cache &= fi != NULL;
2589 	if (fi) {
2590 		struct fib_nh_common *nhc = FIB_RES_NHC(*res);
2591 		struct rtable __rcu **prth;
2592 
2593 		fnhe = find_exception(nhc, fl4->daddr);
2594 		if (!do_cache)
2595 			goto add;
2596 		if (fnhe) {
2597 			prth = &fnhe->fnhe_rth_output;
2598 		} else {
2599 			if (unlikely(fl4->flowi4_flags &
2600 				     FLOWI_FLAG_KNOWN_NH &&
2601 				     !(nhc->nhc_gw_family &&
2602 				       nhc->nhc_scope == RT_SCOPE_LINK))) {
2603 				do_cache = false;
2604 				goto add;
2605 			}
2606 			prth = raw_cpu_ptr(nhc->nhc_pcpu_rth_output);
2607 		}
2608 		rth = rcu_dereference(*prth);
2609 		if (rt_cache_valid(rth) && dst_hold_safe(&rth->dst))
2610 			return rth;
2611 	}
2612 
2613 add:
2614 	rth = rt_dst_alloc(dev_out, flags, type,
2615 			   IN_DEV_ORCONF(in_dev, NOXFRM));
2616 	if (!rth)
2617 		return ERR_PTR(-ENOBUFS);
2618 
2619 	rth->rt_iif = orig_oif;
2620 
2621 	RT_CACHE_STAT_INC(out_slow_tot);
2622 
2623 	if (flags & (RTCF_BROADCAST | RTCF_MULTICAST)) {
2624 		if (flags & RTCF_LOCAL &&
2625 		    !(dev_out->flags & IFF_LOOPBACK)) {
2626 			rth->dst.output = ip_mc_output;
2627 			RT_CACHE_STAT_INC(out_slow_mc);
2628 		}
2629 #ifdef CONFIG_IP_MROUTE
2630 		if (type == RTN_MULTICAST) {
2631 			if (IN_DEV_MFORWARD(in_dev) &&
2632 			    !ipv4_is_local_multicast(fl4->daddr)) {
2633 				rth->dst.input = ip_mr_input;
2634 				rth->dst.output = ip_mc_output;
2635 			}
2636 		}
2637 #endif
2638 	}
2639 
2640 	rt_set_nexthop(rth, fl4->daddr, res, fnhe, fi, type, 0, do_cache);
2641 	lwtunnel_set_redirect(&rth->dst);
2642 
2643 	return rth;
2644 }
2645 
2646 /*
2647  * Major route resolver routine.
2648  */
2649 
ip_route_output_key_hash(struct net * net,struct flowi4 * fl4,const struct sk_buff * skb)2650 struct rtable *ip_route_output_key_hash(struct net *net, struct flowi4 *fl4,
2651 					const struct sk_buff *skb)
2652 {
2653 	struct fib_result res = {
2654 		.type		= RTN_UNSPEC,
2655 		.fi		= NULL,
2656 		.table		= NULL,
2657 		.tclassid	= 0,
2658 	};
2659 	struct rtable *rth;
2660 
2661 	fl4->flowi4_iif = LOOPBACK_IFINDEX;
2662 	ip_rt_fix_tos(fl4);
2663 
2664 	rcu_read_lock();
2665 	rth = ip_route_output_key_hash_rcu(net, fl4, &res, skb);
2666 	rcu_read_unlock();
2667 
2668 	return rth;
2669 }
2670 EXPORT_SYMBOL_GPL(ip_route_output_key_hash);
2671 
ip_route_output_key_hash_rcu(struct net * net,struct flowi4 * fl4,struct fib_result * res,const struct sk_buff * skb)2672 struct rtable *ip_route_output_key_hash_rcu(struct net *net, struct flowi4 *fl4,
2673 					    struct fib_result *res,
2674 					    const struct sk_buff *skb)
2675 {
2676 	struct net_device *dev_out = NULL;
2677 	int orig_oif = fl4->flowi4_oif;
2678 	unsigned int flags = 0;
2679 	struct rtable *rth;
2680 	int err;
2681 
2682 	if (fl4->saddr) {
2683 		if (ipv4_is_multicast(fl4->saddr) ||
2684 		    ipv4_is_lbcast(fl4->saddr) ||
2685 		    ipv4_is_zeronet(fl4->saddr)) {
2686 			rth = ERR_PTR(-EINVAL);
2687 			goto out;
2688 		}
2689 
2690 		rth = ERR_PTR(-ENETUNREACH);
2691 
2692 		/* I removed check for oif == dev_out->oif here.
2693 		 * It was wrong for two reasons:
2694 		 * 1. ip_dev_find(net, saddr) can return wrong iface, if saddr
2695 		 *    is assigned to multiple interfaces.
2696 		 * 2. Moreover, we are allowed to send packets with saddr
2697 		 *    of another iface. --ANK
2698 		 */
2699 
2700 		if (fl4->flowi4_oif == 0 &&
2701 		    (ipv4_is_multicast(fl4->daddr) ||
2702 		     ipv4_is_lbcast(fl4->daddr))) {
2703 			/* It is equivalent to inet_addr_type(saddr) == RTN_LOCAL */
2704 			dev_out = __ip_dev_find(net, fl4->saddr, false);
2705 			if (!dev_out)
2706 				goto out;
2707 
2708 			/* Special hack: user can direct multicasts
2709 			 * and limited broadcast via necessary interface
2710 			 * without fiddling with IP_MULTICAST_IF or IP_PKTINFO.
2711 			 * This hack is not just for fun, it allows
2712 			 * vic,vat and friends to work.
2713 			 * They bind socket to loopback, set ttl to zero
2714 			 * and expect that it will work.
2715 			 * From the viewpoint of routing cache they are broken,
2716 			 * because we are not allowed to build multicast path
2717 			 * with loopback source addr (look, routing cache
2718 			 * cannot know, that ttl is zero, so that packet
2719 			 * will not leave this host and route is valid).
2720 			 * Luckily, this hack is good workaround.
2721 			 */
2722 
2723 			fl4->flowi4_oif = dev_out->ifindex;
2724 			goto make_route;
2725 		}
2726 
2727 		if (!(fl4->flowi4_flags & FLOWI_FLAG_ANYSRC)) {
2728 			/* It is equivalent to inet_addr_type(saddr) == RTN_LOCAL */
2729 			if (!__ip_dev_find(net, fl4->saddr, false))
2730 				goto out;
2731 		}
2732 	}
2733 
2734 
2735 	if (fl4->flowi4_oif) {
2736 		dev_out = dev_get_by_index_rcu(net, fl4->flowi4_oif);
2737 		rth = ERR_PTR(-ENODEV);
2738 		if (!dev_out)
2739 			goto out;
2740 
2741 		/* RACE: Check return value of inet_select_addr instead. */
2742 		if (!(dev_out->flags & IFF_UP) || !__in_dev_get_rcu(dev_out)) {
2743 			rth = ERR_PTR(-ENETUNREACH);
2744 			goto out;
2745 		}
2746 		if (ipv4_is_local_multicast(fl4->daddr) ||
2747 		    ipv4_is_lbcast(fl4->daddr) ||
2748 		    fl4->flowi4_proto == IPPROTO_IGMP) {
2749 			if (!fl4->saddr)
2750 				fl4->saddr = inet_select_addr(dev_out, 0,
2751 							      RT_SCOPE_LINK);
2752 			goto make_route;
2753 		}
2754 		if (!fl4->saddr) {
2755 			if (ipv4_is_multicast(fl4->daddr))
2756 				fl4->saddr = inet_select_addr(dev_out, 0,
2757 							      fl4->flowi4_scope);
2758 			else if (!fl4->daddr)
2759 				fl4->saddr = inet_select_addr(dev_out, 0,
2760 							      RT_SCOPE_HOST);
2761 		}
2762 	}
2763 
2764 	if (!fl4->daddr) {
2765 		fl4->daddr = fl4->saddr;
2766 		if (!fl4->daddr)
2767 			fl4->daddr = fl4->saddr = htonl(INADDR_LOOPBACK);
2768 		dev_out = net->loopback_dev;
2769 		fl4->flowi4_oif = LOOPBACK_IFINDEX;
2770 		res->type = RTN_LOCAL;
2771 		flags |= RTCF_LOCAL;
2772 		goto make_route;
2773 	}
2774 
2775 	err = fib_lookup(net, fl4, res, 0);
2776 	if (err) {
2777 		res->fi = NULL;
2778 		res->table = NULL;
2779 		if (fl4->flowi4_oif &&
2780 		    (ipv4_is_multicast(fl4->daddr) || !fl4->flowi4_l3mdev)) {
2781 			/* Apparently, routing tables are wrong. Assume,
2782 			 * that the destination is on link.
2783 			 *
2784 			 * WHY? DW.
2785 			 * Because we are allowed to send to iface
2786 			 * even if it has NO routes and NO assigned
2787 			 * addresses. When oif is specified, routing
2788 			 * tables are looked up with only one purpose:
2789 			 * to catch if destination is gatewayed, rather than
2790 			 * direct. Moreover, if MSG_DONTROUTE is set,
2791 			 * we send packet, ignoring both routing tables
2792 			 * and ifaddr state. --ANK
2793 			 *
2794 			 *
2795 			 * We could make it even if oif is unknown,
2796 			 * likely IPv6, but we do not.
2797 			 */
2798 
2799 			if (fl4->saddr == 0)
2800 				fl4->saddr = inet_select_addr(dev_out, 0,
2801 							      RT_SCOPE_LINK);
2802 			res->type = RTN_UNICAST;
2803 			goto make_route;
2804 		}
2805 		rth = ERR_PTR(err);
2806 		goto out;
2807 	}
2808 
2809 	if (res->type == RTN_LOCAL) {
2810 		if (!fl4->saddr) {
2811 			if (res->fi->fib_prefsrc)
2812 				fl4->saddr = res->fi->fib_prefsrc;
2813 			else
2814 				fl4->saddr = fl4->daddr;
2815 		}
2816 
2817 		/* L3 master device is the loopback for that domain */
2818 		dev_out = l3mdev_master_dev_rcu(FIB_RES_DEV(*res)) ? :
2819 			net->loopback_dev;
2820 
2821 		/* make sure orig_oif points to fib result device even
2822 		 * though packet rx/tx happens over loopback or l3mdev
2823 		 */
2824 		orig_oif = FIB_RES_OIF(*res);
2825 
2826 		fl4->flowi4_oif = dev_out->ifindex;
2827 		flags |= RTCF_LOCAL;
2828 		goto make_route;
2829 	}
2830 
2831 	fib_select_path(net, res, fl4, skb);
2832 
2833 	dev_out = FIB_RES_DEV(*res);
2834 
2835 make_route:
2836 	rth = __mkroute_output(res, fl4, orig_oif, dev_out, flags);
2837 
2838 out:
2839 	return rth;
2840 }
2841 
2842 static struct dst_ops ipv4_dst_blackhole_ops = {
2843 	.family			= AF_INET,
2844 	.default_advmss		= ipv4_default_advmss,
2845 	.neigh_lookup		= ipv4_neigh_lookup,
2846 	.check			= dst_blackhole_check,
2847 	.cow_metrics		= dst_blackhole_cow_metrics,
2848 	.update_pmtu		= dst_blackhole_update_pmtu,
2849 	.redirect		= dst_blackhole_redirect,
2850 	.mtu			= dst_blackhole_mtu,
2851 };
2852 
ipv4_blackhole_route(struct net * net,struct dst_entry * dst_orig)2853 struct dst_entry *ipv4_blackhole_route(struct net *net, struct dst_entry *dst_orig)
2854 {
2855 	struct rtable *ort = (struct rtable *) dst_orig;
2856 	struct rtable *rt;
2857 
2858 	rt = dst_alloc(&ipv4_dst_blackhole_ops, NULL, 1, DST_OBSOLETE_DEAD, 0);
2859 	if (rt) {
2860 		struct dst_entry *new = &rt->dst;
2861 
2862 		new->__use = 1;
2863 		new->input = dst_discard;
2864 		new->output = dst_discard_out;
2865 
2866 		new->dev = net->loopback_dev;
2867 		netdev_hold(new->dev, &new->dev_tracker, GFP_ATOMIC);
2868 
2869 		rt->rt_is_input = ort->rt_is_input;
2870 		rt->rt_iif = ort->rt_iif;
2871 		rt->rt_pmtu = ort->rt_pmtu;
2872 		rt->rt_mtu_locked = ort->rt_mtu_locked;
2873 
2874 		rt->rt_genid = rt_genid_ipv4(net);
2875 		rt->rt_flags = ort->rt_flags;
2876 		rt->rt_type = ort->rt_type;
2877 		rt->rt_uses_gateway = ort->rt_uses_gateway;
2878 		rt->rt_gw_family = ort->rt_gw_family;
2879 		if (rt->rt_gw_family == AF_INET)
2880 			rt->rt_gw4 = ort->rt_gw4;
2881 		else if (rt->rt_gw_family == AF_INET6)
2882 			rt->rt_gw6 = ort->rt_gw6;
2883 	}
2884 
2885 	dst_release(dst_orig);
2886 
2887 	return rt ? &rt->dst : ERR_PTR(-ENOMEM);
2888 }
2889 
ip_route_output_flow(struct net * net,struct flowi4 * flp4,const struct sock * sk)2890 struct rtable *ip_route_output_flow(struct net *net, struct flowi4 *flp4,
2891 				    const struct sock *sk)
2892 {
2893 	struct rtable *rt = __ip_route_output_key(net, flp4);
2894 
2895 	if (IS_ERR(rt))
2896 		return rt;
2897 
2898 	if (flp4->flowi4_proto) {
2899 		flp4->flowi4_oif = rt->dst.dev->ifindex;
2900 		rt = (struct rtable *)xfrm_lookup_route(net, &rt->dst,
2901 							flowi4_to_flowi(flp4),
2902 							sk, 0);
2903 	}
2904 
2905 	return rt;
2906 }
2907 EXPORT_SYMBOL_GPL(ip_route_output_flow);
2908 
ip_route_output_tunnel(struct sk_buff * skb,struct net_device * dev,struct net * net,__be32 * saddr,const struct ip_tunnel_info * info,u8 protocol,bool use_cache)2909 struct rtable *ip_route_output_tunnel(struct sk_buff *skb,
2910 				      struct net_device *dev,
2911 				      struct net *net, __be32 *saddr,
2912 				      const struct ip_tunnel_info *info,
2913 				      u8 protocol, bool use_cache)
2914 {
2915 #ifdef CONFIG_DST_CACHE
2916 	struct dst_cache *dst_cache;
2917 #endif
2918 	struct rtable *rt = NULL;
2919 	struct flowi4 fl4;
2920 	__u8 tos;
2921 
2922 #ifdef CONFIG_DST_CACHE
2923 	dst_cache = (struct dst_cache *)&info->dst_cache;
2924 	if (use_cache) {
2925 		rt = dst_cache_get_ip4(dst_cache, saddr);
2926 		if (rt)
2927 			return rt;
2928 	}
2929 #endif
2930 	memset(&fl4, 0, sizeof(fl4));
2931 	fl4.flowi4_mark = skb->mark;
2932 	fl4.flowi4_proto = protocol;
2933 	fl4.daddr = info->key.u.ipv4.dst;
2934 	fl4.saddr = info->key.u.ipv4.src;
2935 	tos = info->key.tos;
2936 	fl4.flowi4_tos = RT_TOS(tos);
2937 
2938 	rt = ip_route_output_key(net, &fl4);
2939 	if (IS_ERR(rt)) {
2940 		netdev_dbg(dev, "no route to %pI4\n", &fl4.daddr);
2941 		return ERR_PTR(-ENETUNREACH);
2942 	}
2943 	if (rt->dst.dev == dev) { /* is this necessary? */
2944 		netdev_dbg(dev, "circular route to %pI4\n", &fl4.daddr);
2945 		ip_rt_put(rt);
2946 		return ERR_PTR(-ELOOP);
2947 	}
2948 #ifdef CONFIG_DST_CACHE
2949 	if (use_cache)
2950 		dst_cache_set_ip4(dst_cache, &rt->dst, fl4.saddr);
2951 #endif
2952 	*saddr = fl4.saddr;
2953 	return rt;
2954 }
2955 EXPORT_SYMBOL_GPL(ip_route_output_tunnel);
2956 
2957 /* called with rcu_read_lock held */
rt_fill_info(struct net * net,__be32 dst,__be32 src,struct rtable * rt,u32 table_id,dscp_t dscp,struct flowi4 * fl4,struct sk_buff * skb,u32 portid,u32 seq,unsigned int flags)2958 static int rt_fill_info(struct net *net, __be32 dst, __be32 src,
2959 			struct rtable *rt, u32 table_id, dscp_t dscp,
2960 			struct flowi4 *fl4, struct sk_buff *skb, u32 portid,
2961 			u32 seq, unsigned int flags)
2962 {
2963 	struct rtmsg *r;
2964 	struct nlmsghdr *nlh;
2965 	unsigned long expires = 0;
2966 	u32 error;
2967 	u32 metrics[RTAX_MAX];
2968 
2969 	nlh = nlmsg_put(skb, portid, seq, RTM_NEWROUTE, sizeof(*r), flags);
2970 	if (!nlh)
2971 		return -EMSGSIZE;
2972 
2973 	r = nlmsg_data(nlh);
2974 	r->rtm_family	 = AF_INET;
2975 	r->rtm_dst_len	= 32;
2976 	r->rtm_src_len	= 0;
2977 	r->rtm_tos	= inet_dscp_to_dsfield(dscp);
2978 	r->rtm_table	= table_id < 256 ? table_id : RT_TABLE_COMPAT;
2979 	if (nla_put_u32(skb, RTA_TABLE, table_id))
2980 		goto nla_put_failure;
2981 	r->rtm_type	= rt->rt_type;
2982 	r->rtm_scope	= RT_SCOPE_UNIVERSE;
2983 	r->rtm_protocol = RTPROT_UNSPEC;
2984 	r->rtm_flags	= (rt->rt_flags & ~0xFFFF) | RTM_F_CLONED;
2985 	if (rt->rt_flags & RTCF_NOTIFY)
2986 		r->rtm_flags |= RTM_F_NOTIFY;
2987 	if (IPCB(skb)->flags & IPSKB_DOREDIRECT)
2988 		r->rtm_flags |= RTCF_DOREDIRECT;
2989 
2990 	if (nla_put_in_addr(skb, RTA_DST, dst))
2991 		goto nla_put_failure;
2992 	if (src) {
2993 		r->rtm_src_len = 32;
2994 		if (nla_put_in_addr(skb, RTA_SRC, src))
2995 			goto nla_put_failure;
2996 	}
2997 	if (rt->dst.dev &&
2998 	    nla_put_u32(skb, RTA_OIF, rt->dst.dev->ifindex))
2999 		goto nla_put_failure;
3000 	if (rt->dst.lwtstate &&
3001 	    lwtunnel_fill_encap(skb, rt->dst.lwtstate, RTA_ENCAP, RTA_ENCAP_TYPE) < 0)
3002 		goto nla_put_failure;
3003 #ifdef CONFIG_IP_ROUTE_CLASSID
3004 	if (rt->dst.tclassid &&
3005 	    nla_put_u32(skb, RTA_FLOW, rt->dst.tclassid))
3006 		goto nla_put_failure;
3007 #endif
3008 	if (fl4 && !rt_is_input_route(rt) &&
3009 	    fl4->saddr != src) {
3010 		if (nla_put_in_addr(skb, RTA_PREFSRC, fl4->saddr))
3011 			goto nla_put_failure;
3012 	}
3013 	if (rt->rt_uses_gateway) {
3014 		if (rt->rt_gw_family == AF_INET &&
3015 		    nla_put_in_addr(skb, RTA_GATEWAY, rt->rt_gw4)) {
3016 			goto nla_put_failure;
3017 		} else if (rt->rt_gw_family == AF_INET6) {
3018 			int alen = sizeof(struct in6_addr);
3019 			struct nlattr *nla;
3020 			struct rtvia *via;
3021 
3022 			nla = nla_reserve(skb, RTA_VIA, alen + 2);
3023 			if (!nla)
3024 				goto nla_put_failure;
3025 
3026 			via = nla_data(nla);
3027 			via->rtvia_family = AF_INET6;
3028 			memcpy(via->rtvia_addr, &rt->rt_gw6, alen);
3029 		}
3030 	}
3031 
3032 	expires = rt->dst.expires;
3033 	if (expires) {
3034 		unsigned long now = jiffies;
3035 
3036 		if (time_before(now, expires))
3037 			expires -= now;
3038 		else
3039 			expires = 0;
3040 	}
3041 
3042 	memcpy(metrics, dst_metrics_ptr(&rt->dst), sizeof(metrics));
3043 	if (rt->rt_pmtu && expires)
3044 		metrics[RTAX_MTU - 1] = rt->rt_pmtu;
3045 	if (rt->rt_mtu_locked && expires)
3046 		metrics[RTAX_LOCK - 1] |= BIT(RTAX_MTU);
3047 	if (rtnetlink_put_metrics(skb, metrics) < 0)
3048 		goto nla_put_failure;
3049 
3050 	if (fl4) {
3051 		if (fl4->flowi4_mark &&
3052 		    nla_put_u32(skb, RTA_MARK, fl4->flowi4_mark))
3053 			goto nla_put_failure;
3054 
3055 		if (!uid_eq(fl4->flowi4_uid, INVALID_UID) &&
3056 		    nla_put_u32(skb, RTA_UID,
3057 				from_kuid_munged(current_user_ns(),
3058 						 fl4->flowi4_uid)))
3059 			goto nla_put_failure;
3060 
3061 		if (rt_is_input_route(rt)) {
3062 #ifdef CONFIG_IP_MROUTE
3063 			if (ipv4_is_multicast(dst) &&
3064 			    !ipv4_is_local_multicast(dst) &&
3065 			    IPV4_DEVCONF_ALL(net, MC_FORWARDING)) {
3066 				int err = ipmr_get_route(net, skb,
3067 							 fl4->saddr, fl4->daddr,
3068 							 r, portid);
3069 
3070 				if (err <= 0) {
3071 					if (err == 0)
3072 						return 0;
3073 					goto nla_put_failure;
3074 				}
3075 			} else
3076 #endif
3077 				if (nla_put_u32(skb, RTA_IIF, fl4->flowi4_iif))
3078 					goto nla_put_failure;
3079 		}
3080 	}
3081 
3082 	error = rt->dst.error;
3083 
3084 	if (rtnl_put_cacheinfo(skb, &rt->dst, 0, expires, error) < 0)
3085 		goto nla_put_failure;
3086 
3087 	nlmsg_end(skb, nlh);
3088 	return 0;
3089 
3090 nla_put_failure:
3091 	nlmsg_cancel(skb, nlh);
3092 	return -EMSGSIZE;
3093 }
3094 
fnhe_dump_bucket(struct net * net,struct sk_buff * skb,struct netlink_callback * cb,u32 table_id,struct fnhe_hash_bucket * bucket,int genid,int * fa_index,int fa_start,unsigned int flags)3095 static int fnhe_dump_bucket(struct net *net, struct sk_buff *skb,
3096 			    struct netlink_callback *cb, u32 table_id,
3097 			    struct fnhe_hash_bucket *bucket, int genid,
3098 			    int *fa_index, int fa_start, unsigned int flags)
3099 {
3100 	int i;
3101 
3102 	for (i = 0; i < FNHE_HASH_SIZE; i++) {
3103 		struct fib_nh_exception *fnhe;
3104 
3105 		for (fnhe = rcu_dereference(bucket[i].chain); fnhe;
3106 		     fnhe = rcu_dereference(fnhe->fnhe_next)) {
3107 			struct rtable *rt;
3108 			int err;
3109 
3110 			if (*fa_index < fa_start)
3111 				goto next;
3112 
3113 			if (fnhe->fnhe_genid != genid)
3114 				goto next;
3115 
3116 			if (fnhe->fnhe_expires &&
3117 			    time_after(jiffies, fnhe->fnhe_expires))
3118 				goto next;
3119 
3120 			rt = rcu_dereference(fnhe->fnhe_rth_input);
3121 			if (!rt)
3122 				rt = rcu_dereference(fnhe->fnhe_rth_output);
3123 			if (!rt)
3124 				goto next;
3125 
3126 			err = rt_fill_info(net, fnhe->fnhe_daddr, 0, rt,
3127 					   table_id, 0, NULL, skb,
3128 					   NETLINK_CB(cb->skb).portid,
3129 					   cb->nlh->nlmsg_seq, flags);
3130 			if (err)
3131 				return err;
3132 next:
3133 			(*fa_index)++;
3134 		}
3135 	}
3136 
3137 	return 0;
3138 }
3139 
fib_dump_info_fnhe(struct sk_buff * skb,struct netlink_callback * cb,u32 table_id,struct fib_info * fi,int * fa_index,int fa_start,unsigned int flags)3140 int fib_dump_info_fnhe(struct sk_buff *skb, struct netlink_callback *cb,
3141 		       u32 table_id, struct fib_info *fi,
3142 		       int *fa_index, int fa_start, unsigned int flags)
3143 {
3144 	struct net *net = sock_net(cb->skb->sk);
3145 	int nhsel, genid = fnhe_genid(net);
3146 
3147 	for (nhsel = 0; nhsel < fib_info_num_path(fi); nhsel++) {
3148 		struct fib_nh_common *nhc = fib_info_nhc(fi, nhsel);
3149 		struct fnhe_hash_bucket *bucket;
3150 		int err;
3151 
3152 		if (nhc->nhc_flags & RTNH_F_DEAD)
3153 			continue;
3154 
3155 		rcu_read_lock();
3156 		bucket = rcu_dereference(nhc->nhc_exceptions);
3157 		err = 0;
3158 		if (bucket)
3159 			err = fnhe_dump_bucket(net, skb, cb, table_id, bucket,
3160 					       genid, fa_index, fa_start,
3161 					       flags);
3162 		rcu_read_unlock();
3163 		if (err)
3164 			return err;
3165 	}
3166 
3167 	return 0;
3168 }
3169 
inet_rtm_getroute_build_skb(__be32 src,__be32 dst,u8 ip_proto,__be16 sport,__be16 dport)3170 static struct sk_buff *inet_rtm_getroute_build_skb(__be32 src, __be32 dst,
3171 						   u8 ip_proto, __be16 sport,
3172 						   __be16 dport)
3173 {
3174 	struct sk_buff *skb;
3175 	struct iphdr *iph;
3176 
3177 	skb = alloc_skb(NLMSG_GOODSIZE, GFP_KERNEL);
3178 	if (!skb)
3179 		return NULL;
3180 
3181 	/* Reserve room for dummy headers, this skb can pass
3182 	 * through good chunk of routing engine.
3183 	 */
3184 	skb_reset_mac_header(skb);
3185 	skb_reset_network_header(skb);
3186 	skb->protocol = htons(ETH_P_IP);
3187 	iph = skb_put(skb, sizeof(struct iphdr));
3188 	iph->protocol = ip_proto;
3189 	iph->saddr = src;
3190 	iph->daddr = dst;
3191 	iph->version = 0x4;
3192 	iph->frag_off = 0;
3193 	iph->ihl = 0x5;
3194 	skb_set_transport_header(skb, skb->len);
3195 
3196 	switch (iph->protocol) {
3197 	case IPPROTO_UDP: {
3198 		struct udphdr *udph;
3199 
3200 		udph = skb_put_zero(skb, sizeof(struct udphdr));
3201 		udph->source = sport;
3202 		udph->dest = dport;
3203 		udph->len = htons(sizeof(struct udphdr));
3204 		udph->check = 0;
3205 		break;
3206 	}
3207 	case IPPROTO_TCP: {
3208 		struct tcphdr *tcph;
3209 
3210 		tcph = skb_put_zero(skb, sizeof(struct tcphdr));
3211 		tcph->source	= sport;
3212 		tcph->dest	= dport;
3213 		tcph->doff	= sizeof(struct tcphdr) / 4;
3214 		tcph->rst = 1;
3215 		tcph->check = ~tcp_v4_check(sizeof(struct tcphdr),
3216 					    src, dst, 0);
3217 		break;
3218 	}
3219 	case IPPROTO_ICMP: {
3220 		struct icmphdr *icmph;
3221 
3222 		icmph = skb_put_zero(skb, sizeof(struct icmphdr));
3223 		icmph->type = ICMP_ECHO;
3224 		icmph->code = 0;
3225 	}
3226 	}
3227 
3228 	return skb;
3229 }
3230 
inet_rtm_valid_getroute_req(struct sk_buff * skb,const struct nlmsghdr * nlh,struct nlattr ** tb,struct netlink_ext_ack * extack)3231 static int inet_rtm_valid_getroute_req(struct sk_buff *skb,
3232 				       const struct nlmsghdr *nlh,
3233 				       struct nlattr **tb,
3234 				       struct netlink_ext_ack *extack)
3235 {
3236 	struct rtmsg *rtm;
3237 	int i, err;
3238 
3239 	if (nlh->nlmsg_len < nlmsg_msg_size(sizeof(*rtm))) {
3240 		NL_SET_ERR_MSG(extack,
3241 			       "ipv4: Invalid header for route get request");
3242 		return -EINVAL;
3243 	}
3244 
3245 	if (!netlink_strict_get_check(skb))
3246 		return nlmsg_parse_deprecated(nlh, sizeof(*rtm), tb, RTA_MAX,
3247 					      rtm_ipv4_policy, extack);
3248 
3249 	rtm = nlmsg_data(nlh);
3250 	if ((rtm->rtm_src_len && rtm->rtm_src_len != 32) ||
3251 	    (rtm->rtm_dst_len && rtm->rtm_dst_len != 32) ||
3252 	    rtm->rtm_table || rtm->rtm_protocol ||
3253 	    rtm->rtm_scope || rtm->rtm_type) {
3254 		NL_SET_ERR_MSG(extack, "ipv4: Invalid values in header for route get request");
3255 		return -EINVAL;
3256 	}
3257 
3258 	if (rtm->rtm_flags & ~(RTM_F_NOTIFY |
3259 			       RTM_F_LOOKUP_TABLE |
3260 			       RTM_F_FIB_MATCH)) {
3261 		NL_SET_ERR_MSG(extack, "ipv4: Unsupported rtm_flags for route get request");
3262 		return -EINVAL;
3263 	}
3264 
3265 	err = nlmsg_parse_deprecated_strict(nlh, sizeof(*rtm), tb, RTA_MAX,
3266 					    rtm_ipv4_policy, extack);
3267 	if (err)
3268 		return err;
3269 
3270 	if ((tb[RTA_SRC] && !rtm->rtm_src_len) ||
3271 	    (tb[RTA_DST] && !rtm->rtm_dst_len)) {
3272 		NL_SET_ERR_MSG(extack, "ipv4: rtm_src_len and rtm_dst_len must be 32 for IPv4");
3273 		return -EINVAL;
3274 	}
3275 
3276 	for (i = 0; i <= RTA_MAX; i++) {
3277 		if (!tb[i])
3278 			continue;
3279 
3280 		switch (i) {
3281 		case RTA_IIF:
3282 		case RTA_OIF:
3283 		case RTA_SRC:
3284 		case RTA_DST:
3285 		case RTA_IP_PROTO:
3286 		case RTA_SPORT:
3287 		case RTA_DPORT:
3288 		case RTA_MARK:
3289 		case RTA_UID:
3290 			break;
3291 		default:
3292 			NL_SET_ERR_MSG(extack, "ipv4: Unsupported attribute in route get request");
3293 			return -EINVAL;
3294 		}
3295 	}
3296 
3297 	return 0;
3298 }
3299 
inet_rtm_getroute(struct sk_buff * in_skb,struct nlmsghdr * nlh,struct netlink_ext_ack * extack)3300 static int inet_rtm_getroute(struct sk_buff *in_skb, struct nlmsghdr *nlh,
3301 			     struct netlink_ext_ack *extack)
3302 {
3303 	struct net *net = sock_net(in_skb->sk);
3304 	struct nlattr *tb[RTA_MAX+1];
3305 	u32 table_id = RT_TABLE_MAIN;
3306 	__be16 sport = 0, dport = 0;
3307 	struct fib_result res = {};
3308 	u8 ip_proto = IPPROTO_UDP;
3309 	struct rtable *rt = NULL;
3310 	struct sk_buff *skb;
3311 	struct rtmsg *rtm;
3312 	struct flowi4 fl4 = {};
3313 	__be32 dst = 0;
3314 	__be32 src = 0;
3315 	kuid_t uid;
3316 	u32 iif;
3317 	int err;
3318 	int mark;
3319 
3320 	err = inet_rtm_valid_getroute_req(in_skb, nlh, tb, extack);
3321 	if (err < 0)
3322 		return err;
3323 
3324 	rtm = nlmsg_data(nlh);
3325 	src = tb[RTA_SRC] ? nla_get_in_addr(tb[RTA_SRC]) : 0;
3326 	dst = tb[RTA_DST] ? nla_get_in_addr(tb[RTA_DST]) : 0;
3327 	iif = tb[RTA_IIF] ? nla_get_u32(tb[RTA_IIF]) : 0;
3328 	mark = tb[RTA_MARK] ? nla_get_u32(tb[RTA_MARK]) : 0;
3329 	if (tb[RTA_UID])
3330 		uid = make_kuid(current_user_ns(), nla_get_u32(tb[RTA_UID]));
3331 	else
3332 		uid = (iif ? INVALID_UID : current_uid());
3333 
3334 	if (tb[RTA_IP_PROTO]) {
3335 		err = rtm_getroute_parse_ip_proto(tb[RTA_IP_PROTO],
3336 						  &ip_proto, AF_INET, extack);
3337 		if (err)
3338 			return err;
3339 	}
3340 
3341 	if (tb[RTA_SPORT])
3342 		sport = nla_get_be16(tb[RTA_SPORT]);
3343 
3344 	if (tb[RTA_DPORT])
3345 		dport = nla_get_be16(tb[RTA_DPORT]);
3346 
3347 	skb = inet_rtm_getroute_build_skb(src, dst, ip_proto, sport, dport);
3348 	if (!skb)
3349 		return -ENOBUFS;
3350 
3351 	fl4.daddr = dst;
3352 	fl4.saddr = src;
3353 	fl4.flowi4_tos = rtm->rtm_tos & IPTOS_RT_MASK;
3354 	fl4.flowi4_oif = tb[RTA_OIF] ? nla_get_u32(tb[RTA_OIF]) : 0;
3355 	fl4.flowi4_mark = mark;
3356 	fl4.flowi4_uid = uid;
3357 	if (sport)
3358 		fl4.fl4_sport = sport;
3359 	if (dport)
3360 		fl4.fl4_dport = dport;
3361 	fl4.flowi4_proto = ip_proto;
3362 
3363 	rcu_read_lock();
3364 
3365 	if (iif) {
3366 		struct net_device *dev;
3367 
3368 		dev = dev_get_by_index_rcu(net, iif);
3369 		if (!dev) {
3370 			err = -ENODEV;
3371 			goto errout_rcu;
3372 		}
3373 
3374 		fl4.flowi4_iif = iif; /* for rt_fill_info */
3375 		skb->dev	= dev;
3376 		skb->mark	= mark;
3377 		err = ip_route_input_rcu(skb, dst, src,
3378 					 rtm->rtm_tos & IPTOS_RT_MASK, dev,
3379 					 &res);
3380 
3381 		rt = skb_rtable(skb);
3382 		if (err == 0 && rt->dst.error)
3383 			err = -rt->dst.error;
3384 	} else {
3385 		fl4.flowi4_iif = LOOPBACK_IFINDEX;
3386 		skb->dev = net->loopback_dev;
3387 		rt = ip_route_output_key_hash_rcu(net, &fl4, &res, skb);
3388 		err = 0;
3389 		if (IS_ERR(rt))
3390 			err = PTR_ERR(rt);
3391 		else
3392 			skb_dst_set(skb, &rt->dst);
3393 	}
3394 
3395 	if (err)
3396 		goto errout_rcu;
3397 
3398 	if (rtm->rtm_flags & RTM_F_NOTIFY)
3399 		rt->rt_flags |= RTCF_NOTIFY;
3400 
3401 	if (rtm->rtm_flags & RTM_F_LOOKUP_TABLE)
3402 		table_id = res.table ? res.table->tb_id : 0;
3403 
3404 	/* reset skb for netlink reply msg */
3405 	skb_trim(skb, 0);
3406 	skb_reset_network_header(skb);
3407 	skb_reset_transport_header(skb);
3408 	skb_reset_mac_header(skb);
3409 
3410 	if (rtm->rtm_flags & RTM_F_FIB_MATCH) {
3411 		struct fib_rt_info fri;
3412 
3413 		if (!res.fi) {
3414 			err = fib_props[res.type].error;
3415 			if (!err)
3416 				err = -EHOSTUNREACH;
3417 			goto errout_rcu;
3418 		}
3419 		fri.fi = res.fi;
3420 		fri.tb_id = table_id;
3421 		fri.dst = res.prefix;
3422 		fri.dst_len = res.prefixlen;
3423 		fri.dscp = res.dscp;
3424 		fri.type = rt->rt_type;
3425 		fri.offload = 0;
3426 		fri.trap = 0;
3427 		fri.offload_failed = 0;
3428 		if (res.fa_head) {
3429 			struct fib_alias *fa;
3430 
3431 			hlist_for_each_entry_rcu(fa, res.fa_head, fa_list) {
3432 				u8 slen = 32 - fri.dst_len;
3433 
3434 				if (fa->fa_slen == slen &&
3435 				    fa->tb_id == fri.tb_id &&
3436 				    fa->fa_dscp == fri.dscp &&
3437 				    fa->fa_info == res.fi &&
3438 				    fa->fa_type == fri.type) {
3439 					fri.offload = READ_ONCE(fa->offload);
3440 					fri.trap = READ_ONCE(fa->trap);
3441 					fri.offload_failed =
3442 						READ_ONCE(fa->offload_failed);
3443 					break;
3444 				}
3445 			}
3446 		}
3447 		err = fib_dump_info(skb, NETLINK_CB(in_skb).portid,
3448 				    nlh->nlmsg_seq, RTM_NEWROUTE, &fri, 0);
3449 	} else {
3450 		err = rt_fill_info(net, dst, src, rt, table_id, res.dscp, &fl4,
3451 				   skb, NETLINK_CB(in_skb).portid,
3452 				   nlh->nlmsg_seq, 0);
3453 	}
3454 	if (err < 0)
3455 		goto errout_rcu;
3456 
3457 	rcu_read_unlock();
3458 
3459 	err = rtnl_unicast(skb, net, NETLINK_CB(in_skb).portid);
3460 
3461 errout_free:
3462 	return err;
3463 errout_rcu:
3464 	rcu_read_unlock();
3465 	kfree_skb(skb);
3466 	goto errout_free;
3467 }
3468 
ip_rt_multicast_event(struct in_device * in_dev)3469 void ip_rt_multicast_event(struct in_device *in_dev)
3470 {
3471 	rt_cache_flush(dev_net(in_dev->dev));
3472 }
3473 
3474 #ifdef CONFIG_SYSCTL
3475 static int ip_rt_gc_interval __read_mostly  = 60 * HZ;
3476 static int ip_rt_gc_min_interval __read_mostly	= HZ / 2;
3477 static int ip_rt_gc_elasticity __read_mostly	= 8;
3478 static int ip_min_valid_pmtu __read_mostly	= IPV4_MIN_MTU;
3479 
ipv4_sysctl_rtcache_flush(struct ctl_table * __ctl,int write,void * buffer,size_t * lenp,loff_t * ppos)3480 static int ipv4_sysctl_rtcache_flush(struct ctl_table *__ctl, int write,
3481 		void *buffer, size_t *lenp, loff_t *ppos)
3482 {
3483 	struct net *net = (struct net *)__ctl->extra1;
3484 
3485 	if (write) {
3486 		rt_cache_flush(net);
3487 		fnhe_genid_bump(net);
3488 		return 0;
3489 	}
3490 
3491 	return -EINVAL;
3492 }
3493 
3494 static struct ctl_table ipv4_route_table[] = {
3495 	{
3496 		.procname	= "gc_thresh",
3497 		.data		= &ipv4_dst_ops.gc_thresh,
3498 		.maxlen		= sizeof(int),
3499 		.mode		= 0644,
3500 		.proc_handler	= proc_dointvec,
3501 	},
3502 	{
3503 		.procname	= "max_size",
3504 		.data		= &ip_rt_max_size,
3505 		.maxlen		= sizeof(int),
3506 		.mode		= 0644,
3507 		.proc_handler	= proc_dointvec,
3508 	},
3509 	{
3510 		/*  Deprecated. Use gc_min_interval_ms */
3511 
3512 		.procname	= "gc_min_interval",
3513 		.data		= &ip_rt_gc_min_interval,
3514 		.maxlen		= sizeof(int),
3515 		.mode		= 0644,
3516 		.proc_handler	= proc_dointvec_jiffies,
3517 	},
3518 	{
3519 		.procname	= "gc_min_interval_ms",
3520 		.data		= &ip_rt_gc_min_interval,
3521 		.maxlen		= sizeof(int),
3522 		.mode		= 0644,
3523 		.proc_handler	= proc_dointvec_ms_jiffies,
3524 	},
3525 	{
3526 		.procname	= "gc_timeout",
3527 		.data		= &ip_rt_gc_timeout,
3528 		.maxlen		= sizeof(int),
3529 		.mode		= 0644,
3530 		.proc_handler	= proc_dointvec_jiffies,
3531 	},
3532 	{
3533 		.procname	= "gc_interval",
3534 		.data		= &ip_rt_gc_interval,
3535 		.maxlen		= sizeof(int),
3536 		.mode		= 0644,
3537 		.proc_handler	= proc_dointvec_jiffies,
3538 	},
3539 	{
3540 		.procname	= "redirect_load",
3541 		.data		= &ip_rt_redirect_load,
3542 		.maxlen		= sizeof(int),
3543 		.mode		= 0644,
3544 		.proc_handler	= proc_dointvec,
3545 	},
3546 	{
3547 		.procname	= "redirect_number",
3548 		.data		= &ip_rt_redirect_number,
3549 		.maxlen		= sizeof(int),
3550 		.mode		= 0644,
3551 		.proc_handler	= proc_dointvec,
3552 	},
3553 	{
3554 		.procname	= "redirect_silence",
3555 		.data		= &ip_rt_redirect_silence,
3556 		.maxlen		= sizeof(int),
3557 		.mode		= 0644,
3558 		.proc_handler	= proc_dointvec,
3559 	},
3560 	{
3561 		.procname	= "error_cost",
3562 		.data		= &ip_rt_error_cost,
3563 		.maxlen		= sizeof(int),
3564 		.mode		= 0644,
3565 		.proc_handler	= proc_dointvec,
3566 	},
3567 	{
3568 		.procname	= "error_burst",
3569 		.data		= &ip_rt_error_burst,
3570 		.maxlen		= sizeof(int),
3571 		.mode		= 0644,
3572 		.proc_handler	= proc_dointvec,
3573 	},
3574 	{
3575 		.procname	= "gc_elasticity",
3576 		.data		= &ip_rt_gc_elasticity,
3577 		.maxlen		= sizeof(int),
3578 		.mode		= 0644,
3579 		.proc_handler	= proc_dointvec,
3580 	},
3581 	{ }
3582 };
3583 
3584 static const char ipv4_route_flush_procname[] = "flush";
3585 
3586 static struct ctl_table ipv4_route_netns_table[] = {
3587 	{
3588 		.procname	= ipv4_route_flush_procname,
3589 		.maxlen		= sizeof(int),
3590 		.mode		= 0200,
3591 		.proc_handler	= ipv4_sysctl_rtcache_flush,
3592 	},
3593 	{
3594 		.procname       = "min_pmtu",
3595 		.data           = &init_net.ipv4.ip_rt_min_pmtu,
3596 		.maxlen         = sizeof(int),
3597 		.mode           = 0644,
3598 		.proc_handler   = proc_dointvec_minmax,
3599 		.extra1         = &ip_min_valid_pmtu,
3600 	},
3601 	{
3602 		.procname       = "mtu_expires",
3603 		.data           = &init_net.ipv4.ip_rt_mtu_expires,
3604 		.maxlen         = sizeof(int),
3605 		.mode           = 0644,
3606 		.proc_handler   = proc_dointvec_jiffies,
3607 	},
3608 	{
3609 		.procname   = "min_adv_mss",
3610 		.data       = &init_net.ipv4.ip_rt_min_advmss,
3611 		.maxlen     = sizeof(int),
3612 		.mode       = 0644,
3613 		.proc_handler   = proc_dointvec,
3614 	},
3615 	{ },
3616 };
3617 
sysctl_route_net_init(struct net * net)3618 static __net_init int sysctl_route_net_init(struct net *net)
3619 {
3620 	struct ctl_table *tbl;
3621 	size_t table_size = ARRAY_SIZE(ipv4_route_netns_table);
3622 
3623 	tbl = ipv4_route_netns_table;
3624 	if (!net_eq(net, &init_net)) {
3625 		int i;
3626 
3627 		tbl = kmemdup(tbl, sizeof(ipv4_route_netns_table), GFP_KERNEL);
3628 		if (!tbl)
3629 			goto err_dup;
3630 
3631 		/* Don't export non-whitelisted sysctls to unprivileged users */
3632 		if (net->user_ns != &init_user_ns) {
3633 			if (tbl[0].procname != ipv4_route_flush_procname) {
3634 				tbl[0].procname = NULL;
3635 				table_size = 0;
3636 			}
3637 		}
3638 
3639 		/* Update the variables to point into the current struct net
3640 		 * except for the first element flush
3641 		 */
3642 		for (i = 1; i < ARRAY_SIZE(ipv4_route_netns_table) - 1; i++)
3643 			tbl[i].data += (void *)net - (void *)&init_net;
3644 	}
3645 	tbl[0].extra1 = net;
3646 
3647 	net->ipv4.route_hdr = register_net_sysctl_sz(net, "net/ipv4/route",
3648 						     tbl, table_size);
3649 	if (!net->ipv4.route_hdr)
3650 		goto err_reg;
3651 	return 0;
3652 
3653 err_reg:
3654 	if (tbl != ipv4_route_netns_table)
3655 		kfree(tbl);
3656 err_dup:
3657 	return -ENOMEM;
3658 }
3659 
sysctl_route_net_exit(struct net * net)3660 static __net_exit void sysctl_route_net_exit(struct net *net)
3661 {
3662 	struct ctl_table *tbl;
3663 
3664 	tbl = net->ipv4.route_hdr->ctl_table_arg;
3665 	unregister_net_sysctl_table(net->ipv4.route_hdr);
3666 	BUG_ON(tbl == ipv4_route_netns_table);
3667 	kfree(tbl);
3668 }
3669 
3670 static __net_initdata struct pernet_operations sysctl_route_ops = {
3671 	.init = sysctl_route_net_init,
3672 	.exit = sysctl_route_net_exit,
3673 };
3674 #endif
3675 
netns_ip_rt_init(struct net * net)3676 static __net_init int netns_ip_rt_init(struct net *net)
3677 {
3678 	/* Set default value for namespaceified sysctls */
3679 	net->ipv4.ip_rt_min_pmtu = DEFAULT_MIN_PMTU;
3680 	net->ipv4.ip_rt_mtu_expires = DEFAULT_MTU_EXPIRES;
3681 	net->ipv4.ip_rt_min_advmss = DEFAULT_MIN_ADVMSS;
3682 	return 0;
3683 }
3684 
3685 static struct pernet_operations __net_initdata ip_rt_ops = {
3686 	.init = netns_ip_rt_init,
3687 };
3688 
rt_genid_init(struct net * net)3689 static __net_init int rt_genid_init(struct net *net)
3690 {
3691 	atomic_set(&net->ipv4.rt_genid, 0);
3692 	atomic_set(&net->fnhe_genid, 0);
3693 	atomic_set(&net->ipv4.dev_addr_genid, get_random_u32());
3694 	return 0;
3695 }
3696 
3697 static __net_initdata struct pernet_operations rt_genid_ops = {
3698 	.init = rt_genid_init,
3699 };
3700 
ipv4_inetpeer_init(struct net * net)3701 static int __net_init ipv4_inetpeer_init(struct net *net)
3702 {
3703 	struct inet_peer_base *bp = kmalloc(sizeof(*bp), GFP_KERNEL);
3704 
3705 	if (!bp)
3706 		return -ENOMEM;
3707 	inet_peer_base_init(bp);
3708 	net->ipv4.peers = bp;
3709 	return 0;
3710 }
3711 
ipv4_inetpeer_exit(struct net * net)3712 static void __net_exit ipv4_inetpeer_exit(struct net *net)
3713 {
3714 	struct inet_peer_base *bp = net->ipv4.peers;
3715 
3716 	net->ipv4.peers = NULL;
3717 	inetpeer_invalidate_tree(bp);
3718 	kfree(bp);
3719 }
3720 
3721 static __net_initdata struct pernet_operations ipv4_inetpeer_ops = {
3722 	.init	=	ipv4_inetpeer_init,
3723 	.exit	=	ipv4_inetpeer_exit,
3724 };
3725 
3726 #ifdef CONFIG_IP_ROUTE_CLASSID
3727 struct ip_rt_acct __percpu *ip_rt_acct __read_mostly;
3728 #endif /* CONFIG_IP_ROUTE_CLASSID */
3729 
ip_rt_init(void)3730 int __init ip_rt_init(void)
3731 {
3732 	void *idents_hash;
3733 	int cpu;
3734 
3735 	/* For modern hosts, this will use 2 MB of memory */
3736 	idents_hash = alloc_large_system_hash("IP idents",
3737 					      sizeof(*ip_idents) + sizeof(*ip_tstamps),
3738 					      0,
3739 					      16, /* one bucket per 64 KB */
3740 					      HASH_ZERO,
3741 					      NULL,
3742 					      &ip_idents_mask,
3743 					      2048,
3744 					      256*1024);
3745 
3746 	ip_idents = idents_hash;
3747 
3748 	get_random_bytes(ip_idents, (ip_idents_mask + 1) * sizeof(*ip_idents));
3749 
3750 	ip_tstamps = idents_hash + (ip_idents_mask + 1) * sizeof(*ip_idents);
3751 
3752 	for_each_possible_cpu(cpu) {
3753 		struct uncached_list *ul = &per_cpu(rt_uncached_list, cpu);
3754 
3755 		INIT_LIST_HEAD(&ul->head);
3756 		INIT_LIST_HEAD(&ul->quarantine);
3757 		spin_lock_init(&ul->lock);
3758 	}
3759 #ifdef CONFIG_IP_ROUTE_CLASSID
3760 	ip_rt_acct = __alloc_percpu(256 * sizeof(struct ip_rt_acct), __alignof__(struct ip_rt_acct));
3761 	if (!ip_rt_acct)
3762 		panic("IP: failed to allocate ip_rt_acct\n");
3763 #endif
3764 
3765 	ipv4_dst_ops.kmem_cachep =
3766 		kmem_cache_create("ip_dst_cache", sizeof(struct rtable), 0,
3767 				  SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
3768 
3769 	ipv4_dst_blackhole_ops.kmem_cachep = ipv4_dst_ops.kmem_cachep;
3770 
3771 	if (dst_entries_init(&ipv4_dst_ops) < 0)
3772 		panic("IP: failed to allocate ipv4_dst_ops counter\n");
3773 
3774 	if (dst_entries_init(&ipv4_dst_blackhole_ops) < 0)
3775 		panic("IP: failed to allocate ipv4_dst_blackhole_ops counter\n");
3776 
3777 	ipv4_dst_ops.gc_thresh = ~0;
3778 	ip_rt_max_size = INT_MAX;
3779 
3780 	devinet_init();
3781 	ip_fib_init();
3782 
3783 	if (ip_rt_proc_init())
3784 		pr_err("Unable to create route proc files\n");
3785 #ifdef CONFIG_XFRM
3786 	xfrm_init();
3787 	xfrm4_init();
3788 #endif
3789 	rtnl_register(PF_INET, RTM_GETROUTE, inet_rtm_getroute, NULL,
3790 		      RTNL_FLAG_DOIT_UNLOCKED);
3791 
3792 #ifdef CONFIG_SYSCTL
3793 	register_pernet_subsys(&sysctl_route_ops);
3794 #endif
3795 	register_pernet_subsys(&ip_rt_ops);
3796 	register_pernet_subsys(&rt_genid_ops);
3797 	register_pernet_subsys(&ipv4_inetpeer_ops);
3798 	return 0;
3799 }
3800 
3801 #ifdef CONFIG_SYSCTL
3802 /*
3803  * We really need to sanitize the damn ipv4 init order, then all
3804  * this nonsense will go away.
3805  */
ip_static_sysctl_init(void)3806 void __init ip_static_sysctl_init(void)
3807 {
3808 	register_net_sysctl(&init_net, "net/ipv4/route", ipv4_route_table);
3809 }
3810 #endif
3811