xref: /linux/net/ipv4/fib_semantics.c (revision 1a9239bb4253f9076b5b4b2a1a4e8d7defd77a95)
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  *		IPv4 Forwarding Information Base: semantics.
8  *
9  * Authors:	Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
10  */
11 
12 #include <linux/uaccess.h>
13 #include <linux/bitops.h>
14 #include <linux/types.h>
15 #include <linux/kernel.h>
16 #include <linux/jiffies.h>
17 #include <linux/mm.h>
18 #include <linux/string.h>
19 #include <linux/socket.h>
20 #include <linux/sockios.h>
21 #include <linux/errno.h>
22 #include <linux/in.h>
23 #include <linux/inet.h>
24 #include <linux/inetdevice.h>
25 #include <linux/netdevice.h>
26 #include <linux/if_arp.h>
27 #include <linux/proc_fs.h>
28 #include <linux/skbuff.h>
29 #include <linux/init.h>
30 #include <linux/slab.h>
31 #include <linux/netlink.h>
32 #include <linux/hash.h>
33 #include <linux/nospec.h>
34 
35 #include <net/arp.h>
36 #include <net/inet_dscp.h>
37 #include <net/ip.h>
38 #include <net/protocol.h>
39 #include <net/route.h>
40 #include <net/tcp.h>
41 #include <net/sock.h>
42 #include <net/ip_fib.h>
43 #include <net/ip6_fib.h>
44 #include <net/nexthop.h>
45 #include <net/netlink.h>
46 #include <net/rtnh.h>
47 #include <net/lwtunnel.h>
48 #include <net/fib_notifier.h>
49 #include <net/addrconf.h>
50 
51 #include "fib_lookup.h"
52 
53 /* for_nexthops and change_nexthops only used when nexthop object
54  * is not set in a fib_info. The logic within can reference fib_nh.
55  */
56 #ifdef CONFIG_IP_ROUTE_MULTIPATH
57 
58 #define for_nexthops(fi) {						\
59 	int nhsel; const struct fib_nh *nh;				\
60 	for (nhsel = 0, nh = (fi)->fib_nh;				\
61 	     nhsel < fib_info_num_path((fi));				\
62 	     nh++, nhsel++)
63 
64 #define change_nexthops(fi) {						\
65 	int nhsel; struct fib_nh *nexthop_nh;				\
66 	for (nhsel = 0,	nexthop_nh = (struct fib_nh *)((fi)->fib_nh);	\
67 	     nhsel < fib_info_num_path((fi));				\
68 	     nexthop_nh++, nhsel++)
69 
70 #else /* CONFIG_IP_ROUTE_MULTIPATH */
71 
72 /* Hope, that gcc will optimize it to get rid of dummy loop */
73 
74 #define for_nexthops(fi) {						\
75 	int nhsel; const struct fib_nh *nh = (fi)->fib_nh;		\
76 	for (nhsel = 0; nhsel < 1; nhsel++)
77 
78 #define change_nexthops(fi) {						\
79 	int nhsel;							\
80 	struct fib_nh *nexthop_nh = (struct fib_nh *)((fi)->fib_nh);	\
81 	for (nhsel = 0; nhsel < 1; nhsel++)
82 
83 #endif /* CONFIG_IP_ROUTE_MULTIPATH */
84 
85 #define endfor_nexthops(fi) }
86 
87 
88 const struct fib_prop fib_props[RTN_MAX + 1] = {
89 	[RTN_UNSPEC] = {
90 		.error	= 0,
91 		.scope	= RT_SCOPE_NOWHERE,
92 	},
93 	[RTN_UNICAST] = {
94 		.error	= 0,
95 		.scope	= RT_SCOPE_UNIVERSE,
96 	},
97 	[RTN_LOCAL] = {
98 		.error	= 0,
99 		.scope	= RT_SCOPE_HOST,
100 	},
101 	[RTN_BROADCAST] = {
102 		.error	= 0,
103 		.scope	= RT_SCOPE_LINK,
104 	},
105 	[RTN_ANYCAST] = {
106 		.error	= 0,
107 		.scope	= RT_SCOPE_LINK,
108 	},
109 	[RTN_MULTICAST] = {
110 		.error	= 0,
111 		.scope	= RT_SCOPE_UNIVERSE,
112 	},
113 	[RTN_BLACKHOLE] = {
114 		.error	= -EINVAL,
115 		.scope	= RT_SCOPE_UNIVERSE,
116 	},
117 	[RTN_UNREACHABLE] = {
118 		.error	= -EHOSTUNREACH,
119 		.scope	= RT_SCOPE_UNIVERSE,
120 	},
121 	[RTN_PROHIBIT] = {
122 		.error	= -EACCES,
123 		.scope	= RT_SCOPE_UNIVERSE,
124 	},
125 	[RTN_THROW] = {
126 		.error	= -EAGAIN,
127 		.scope	= RT_SCOPE_UNIVERSE,
128 	},
129 	[RTN_NAT] = {
130 		.error	= -EINVAL,
131 		.scope	= RT_SCOPE_NOWHERE,
132 	},
133 	[RTN_XRESOLVE] = {
134 		.error	= -EINVAL,
135 		.scope	= RT_SCOPE_NOWHERE,
136 	},
137 };
138 
rt_fibinfo_free(struct rtable __rcu ** rtp)139 static void rt_fibinfo_free(struct rtable __rcu **rtp)
140 {
141 	struct rtable *rt = rcu_dereference_protected(*rtp, 1);
142 
143 	if (!rt)
144 		return;
145 
146 	/* Not even needed : RCU_INIT_POINTER(*rtp, NULL);
147 	 * because we waited an RCU grace period before calling
148 	 * free_fib_info_rcu()
149 	 */
150 
151 	dst_dev_put(&rt->dst);
152 	dst_release_immediate(&rt->dst);
153 }
154 
free_nh_exceptions(struct fib_nh_common * nhc)155 static void free_nh_exceptions(struct fib_nh_common *nhc)
156 {
157 	struct fnhe_hash_bucket *hash;
158 	int i;
159 
160 	hash = rcu_dereference_protected(nhc->nhc_exceptions, 1);
161 	if (!hash)
162 		return;
163 	for (i = 0; i < FNHE_HASH_SIZE; i++) {
164 		struct fib_nh_exception *fnhe;
165 
166 		fnhe = rcu_dereference_protected(hash[i].chain, 1);
167 		while (fnhe) {
168 			struct fib_nh_exception *next;
169 
170 			next = rcu_dereference_protected(fnhe->fnhe_next, 1);
171 
172 			rt_fibinfo_free(&fnhe->fnhe_rth_input);
173 			rt_fibinfo_free(&fnhe->fnhe_rth_output);
174 
175 			kfree(fnhe);
176 
177 			fnhe = next;
178 		}
179 	}
180 	kfree(hash);
181 }
182 
rt_fibinfo_free_cpus(struct rtable __rcu * __percpu * rtp)183 static void rt_fibinfo_free_cpus(struct rtable __rcu * __percpu *rtp)
184 {
185 	int cpu;
186 
187 	if (!rtp)
188 		return;
189 
190 	for_each_possible_cpu(cpu) {
191 		struct rtable *rt;
192 
193 		rt = rcu_dereference_protected(*per_cpu_ptr(rtp, cpu), 1);
194 		if (rt) {
195 			dst_dev_put(&rt->dst);
196 			dst_release_immediate(&rt->dst);
197 		}
198 	}
199 	free_percpu(rtp);
200 }
201 
fib_nh_common_release(struct fib_nh_common * nhc)202 void fib_nh_common_release(struct fib_nh_common *nhc)
203 {
204 	netdev_put(nhc->nhc_dev, &nhc->nhc_dev_tracker);
205 	lwtstate_put(nhc->nhc_lwtstate);
206 	rt_fibinfo_free_cpus(nhc->nhc_pcpu_rth_output);
207 	rt_fibinfo_free(&nhc->nhc_rth_input);
208 	free_nh_exceptions(nhc);
209 }
210 EXPORT_SYMBOL_GPL(fib_nh_common_release);
211 
fib_nh_release(struct net * net,struct fib_nh * fib_nh)212 void fib_nh_release(struct net *net, struct fib_nh *fib_nh)
213 {
214 #ifdef CONFIG_IP_ROUTE_CLASSID
215 	if (fib_nh->nh_tclassid)
216 		atomic_dec(&net->ipv4.fib_num_tclassid_users);
217 #endif
218 	fib_nh_common_release(&fib_nh->nh_common);
219 }
220 
221 /* Release a nexthop info record */
free_fib_info_rcu(struct rcu_head * head)222 static void free_fib_info_rcu(struct rcu_head *head)
223 {
224 	struct fib_info *fi = container_of(head, struct fib_info, rcu);
225 
226 	if (fi->nh) {
227 		nexthop_put(fi->nh);
228 	} else {
229 		change_nexthops(fi) {
230 			fib_nh_release(fi->fib_net, nexthop_nh);
231 		} endfor_nexthops(fi);
232 	}
233 
234 	ip_fib_metrics_put(fi->fib_metrics);
235 
236 	kfree(fi);
237 }
238 
free_fib_info(struct fib_info * fi)239 void free_fib_info(struct fib_info *fi)
240 {
241 	if (fi->fib_dead == 0) {
242 		pr_warn("Freeing alive fib_info %p\n", fi);
243 		return;
244 	}
245 
246 	call_rcu_hurry(&fi->rcu, free_fib_info_rcu);
247 }
248 EXPORT_SYMBOL_GPL(free_fib_info);
249 
fib_release_info(struct fib_info * fi)250 void fib_release_info(struct fib_info *fi)
251 {
252 	ASSERT_RTNL();
253 	if (fi && refcount_dec_and_test(&fi->fib_treeref)) {
254 		hlist_del(&fi->fib_hash);
255 		fi->fib_net->ipv4.fib_info_cnt--;
256 
257 		if (fi->fib_prefsrc)
258 			hlist_del(&fi->fib_lhash);
259 		if (fi->nh) {
260 			list_del(&fi->nh_list);
261 		} else {
262 			change_nexthops(fi) {
263 				if (!nexthop_nh->fib_nh_dev)
264 					continue;
265 				hlist_del_rcu(&nexthop_nh->nh_hash);
266 			} endfor_nexthops(fi)
267 		}
268 		/* Paired with READ_ONCE() from fib_table_lookup() */
269 		WRITE_ONCE(fi->fib_dead, 1);
270 		fib_info_put(fi);
271 	}
272 }
273 
nh_comp(struct fib_info * fi,struct fib_info * ofi)274 static inline int nh_comp(struct fib_info *fi, struct fib_info *ofi)
275 {
276 	const struct fib_nh *onh;
277 
278 	if (fi->nh || ofi->nh)
279 		return nexthop_cmp(fi->nh, ofi->nh) ? 0 : -1;
280 
281 	if (ofi->fib_nhs == 0)
282 		return 0;
283 
284 	for_nexthops(fi) {
285 		onh = fib_info_nh(ofi, nhsel);
286 
287 		if (nh->fib_nh_oif != onh->fib_nh_oif ||
288 		    nh->fib_nh_gw_family != onh->fib_nh_gw_family ||
289 		    nh->fib_nh_scope != onh->fib_nh_scope ||
290 #ifdef CONFIG_IP_ROUTE_MULTIPATH
291 		    nh->fib_nh_weight != onh->fib_nh_weight ||
292 #endif
293 #ifdef CONFIG_IP_ROUTE_CLASSID
294 		    nh->nh_tclassid != onh->nh_tclassid ||
295 #endif
296 		    lwtunnel_cmp_encap(nh->fib_nh_lws, onh->fib_nh_lws) ||
297 		    ((nh->fib_nh_flags ^ onh->fib_nh_flags) & ~RTNH_COMPARE_MASK))
298 			return -1;
299 
300 		if (nh->fib_nh_gw_family == AF_INET &&
301 		    nh->fib_nh_gw4 != onh->fib_nh_gw4)
302 			return -1;
303 
304 		if (nh->fib_nh_gw_family == AF_INET6 &&
305 		    ipv6_addr_cmp(&nh->fib_nh_gw6, &onh->fib_nh_gw6))
306 			return -1;
307 	} endfor_nexthops(fi);
308 	return 0;
309 }
310 
fib_nh_head(struct net_device * dev)311 static struct hlist_head *fib_nh_head(struct net_device *dev)
312 {
313 	return &dev->fib_nh_head;
314 }
315 
fib_info_hashfn_1(int init_val,u8 protocol,u8 scope,u32 prefsrc,u32 priority)316 static unsigned int fib_info_hashfn_1(int init_val, u8 protocol, u8 scope,
317 				      u32 prefsrc, u32 priority)
318 {
319 	unsigned int val = init_val;
320 
321 	val ^= (protocol << 8) | scope;
322 	val ^= prefsrc;
323 	val ^= priority;
324 
325 	return val;
326 }
327 
fib_info_hashfn_result(const struct net * net,unsigned int val)328 static unsigned int fib_info_hashfn_result(const struct net *net,
329 					   unsigned int val)
330 {
331 	return hash_32(val ^ net_hash_mix(net), net->ipv4.fib_info_hash_bits);
332 }
333 
fib_info_hash_bucket(struct fib_info * fi)334 static struct hlist_head *fib_info_hash_bucket(struct fib_info *fi)
335 {
336 	struct net *net = fi->fib_net;
337 	unsigned int val;
338 
339 	val = fib_info_hashfn_1(fi->fib_nhs, fi->fib_protocol,
340 				fi->fib_scope, (__force u32)fi->fib_prefsrc,
341 				fi->fib_priority);
342 
343 	if (fi->nh) {
344 		val ^= fi->nh->id;
345 	} else {
346 		for_nexthops(fi) {
347 			val ^= nh->fib_nh_oif;
348 		} endfor_nexthops(fi)
349 	}
350 
351 	return &net->ipv4.fib_info_hash[fib_info_hashfn_result(net, val)];
352 }
353 
fib_info_laddrhash_bucket(const struct net * net,__be32 val)354 static struct hlist_head *fib_info_laddrhash_bucket(const struct net *net,
355 						    __be32 val)
356 {
357 	unsigned int hash_bits = net->ipv4.fib_info_hash_bits;
358 	u32 slot;
359 
360 	slot = hash_32(net_hash_mix(net) ^ (__force u32)val, hash_bits);
361 
362 	return &net->ipv4.fib_info_hash[(1 << hash_bits) + slot];
363 }
364 
fib_info_hash_alloc(unsigned int hash_bits)365 static struct hlist_head *fib_info_hash_alloc(unsigned int hash_bits)
366 {
367 	/* The second half is used for prefsrc */
368 	return kvcalloc((1 << hash_bits) * 2, sizeof(struct hlist_head *),
369 			GFP_KERNEL);
370 }
371 
fib_info_hash_free(struct hlist_head * head)372 static void fib_info_hash_free(struct hlist_head *head)
373 {
374 	kvfree(head);
375 }
376 
fib_info_hash_grow(struct net * net)377 static void fib_info_hash_grow(struct net *net)
378 {
379 	unsigned int old_size = 1 << net->ipv4.fib_info_hash_bits;
380 	struct hlist_head *new_info_hash, *old_info_hash;
381 	unsigned int i;
382 
383 	if (net->ipv4.fib_info_cnt < old_size)
384 		return;
385 
386 	new_info_hash = fib_info_hash_alloc(net->ipv4.fib_info_hash_bits + 1);
387 	if (!new_info_hash)
388 		return;
389 
390 	old_info_hash = net->ipv4.fib_info_hash;
391 	net->ipv4.fib_info_hash = new_info_hash;
392 	net->ipv4.fib_info_hash_bits += 1;
393 
394 	for (i = 0; i < old_size; i++) {
395 		struct hlist_head *head = &old_info_hash[i];
396 		struct hlist_node *n;
397 		struct fib_info *fi;
398 
399 		hlist_for_each_entry_safe(fi, n, head, fib_hash)
400 			hlist_add_head(&fi->fib_hash, fib_info_hash_bucket(fi));
401 	}
402 
403 	for (i = 0; i < old_size; i++) {
404 		struct hlist_head *lhead = &old_info_hash[old_size + i];
405 		struct hlist_node *n;
406 		struct fib_info *fi;
407 
408 		hlist_for_each_entry_safe(fi, n, lhead, fib_lhash)
409 			hlist_add_head(&fi->fib_lhash,
410 				       fib_info_laddrhash_bucket(fi->fib_net,
411 								 fi->fib_prefsrc));
412 	}
413 
414 	fib_info_hash_free(old_info_hash);
415 }
416 
417 /* no metrics, only nexthop id */
fib_find_info_nh(struct net * net,const struct fib_config * cfg)418 static struct fib_info *fib_find_info_nh(struct net *net,
419 					 const struct fib_config *cfg)
420 {
421 	struct hlist_head *head;
422 	struct fib_info *fi;
423 	unsigned int hash;
424 
425 	hash = fib_info_hashfn_1(cfg->fc_nh_id,
426 				 cfg->fc_protocol, cfg->fc_scope,
427 				 (__force u32)cfg->fc_prefsrc,
428 				 cfg->fc_priority);
429 	hash = fib_info_hashfn_result(net, hash);
430 	head = &net->ipv4.fib_info_hash[hash];
431 
432 	hlist_for_each_entry(fi, head, fib_hash) {
433 		if (!fi->nh || fi->nh->id != cfg->fc_nh_id)
434 			continue;
435 
436 		if (cfg->fc_protocol == fi->fib_protocol &&
437 		    cfg->fc_scope == fi->fib_scope &&
438 		    cfg->fc_prefsrc == fi->fib_prefsrc &&
439 		    cfg->fc_priority == fi->fib_priority &&
440 		    cfg->fc_type == fi->fib_type &&
441 		    cfg->fc_table == fi->fib_tb_id &&
442 		    !((cfg->fc_flags ^ fi->fib_flags) & ~RTNH_COMPARE_MASK))
443 			return fi;
444 	}
445 
446 	return NULL;
447 }
448 
fib_find_info(struct fib_info * nfi)449 static struct fib_info *fib_find_info(struct fib_info *nfi)
450 {
451 	struct hlist_head *head = fib_info_hash_bucket(nfi);
452 	struct fib_info *fi;
453 
454 	hlist_for_each_entry(fi, head, fib_hash) {
455 		if (fi->fib_nhs != nfi->fib_nhs)
456 			continue;
457 
458 		if (nfi->fib_protocol == fi->fib_protocol &&
459 		    nfi->fib_scope == fi->fib_scope &&
460 		    nfi->fib_prefsrc == fi->fib_prefsrc &&
461 		    nfi->fib_priority == fi->fib_priority &&
462 		    nfi->fib_type == fi->fib_type &&
463 		    nfi->fib_tb_id == fi->fib_tb_id &&
464 		    memcmp(nfi->fib_metrics, fi->fib_metrics,
465 			   sizeof(u32) * RTAX_MAX) == 0 &&
466 		    !((nfi->fib_flags ^ fi->fib_flags) & ~RTNH_COMPARE_MASK) &&
467 		    nh_comp(fi, nfi) == 0)
468 			return fi;
469 	}
470 
471 	return NULL;
472 }
473 
474 /* Check, that the gateway is already configured.
475  * Used only by redirect accept routine, under rcu_read_lock();
476  */
ip_fib_check_default(__be32 gw,struct net_device * dev)477 int ip_fib_check_default(__be32 gw, struct net_device *dev)
478 {
479 	struct hlist_head *head;
480 	struct fib_nh *nh;
481 
482 	head = fib_nh_head(dev);
483 
484 	hlist_for_each_entry_rcu(nh, head, nh_hash) {
485 		DEBUG_NET_WARN_ON_ONCE(nh->fib_nh_dev != dev);
486 		if (nh->fib_nh_gw4 == gw &&
487 		    !(nh->fib_nh_flags & RTNH_F_DEAD)) {
488 			return 0;
489 		}
490 	}
491 
492 	return -1;
493 }
494 
fib_nlmsg_size(struct fib_info * fi)495 size_t fib_nlmsg_size(struct fib_info *fi)
496 {
497 	size_t payload = NLMSG_ALIGN(sizeof(struct rtmsg))
498 			 + nla_total_size(4) /* RTA_TABLE */
499 			 + nla_total_size(4) /* RTA_DST */
500 			 + nla_total_size(4) /* RTA_PRIORITY */
501 			 + nla_total_size(4) /* RTA_PREFSRC */
502 			 + nla_total_size(TCP_CA_NAME_MAX); /* RTAX_CC_ALGO */
503 	unsigned int nhs = fib_info_num_path(fi);
504 
505 	/* space for nested metrics */
506 	payload += nla_total_size((RTAX_MAX * nla_total_size(4)));
507 
508 	if (fi->nh)
509 		payload += nla_total_size(4); /* RTA_NH_ID */
510 
511 	if (nhs) {
512 		size_t nh_encapsize = 0;
513 		/* Also handles the special case nhs == 1 */
514 
515 		/* each nexthop is packed in an attribute */
516 		size_t nhsize = nla_total_size(sizeof(struct rtnexthop));
517 		unsigned int i;
518 
519 		/* may contain flow and gateway attribute */
520 		nhsize += 2 * nla_total_size(4);
521 
522 		/* grab encap info */
523 		for (i = 0; i < fib_info_num_path(fi); i++) {
524 			struct fib_nh_common *nhc = fib_info_nhc(fi, i);
525 
526 			if (nhc->nhc_lwtstate) {
527 				/* RTA_ENCAP_TYPE */
528 				nh_encapsize += lwtunnel_get_encap_size(
529 						nhc->nhc_lwtstate);
530 				/* RTA_ENCAP */
531 				nh_encapsize +=  nla_total_size(2);
532 			}
533 		}
534 
535 		/* all nexthops are packed in a nested attribute */
536 		payload += nla_total_size((nhs * nhsize) + nh_encapsize);
537 
538 	}
539 
540 	return payload;
541 }
542 
rtmsg_fib(int event,__be32 key,struct fib_alias * fa,int dst_len,u32 tb_id,const struct nl_info * info,unsigned int nlm_flags)543 void rtmsg_fib(int event, __be32 key, struct fib_alias *fa,
544 	       int dst_len, u32 tb_id, const struct nl_info *info,
545 	       unsigned int nlm_flags)
546 {
547 	struct fib_rt_info fri;
548 	struct sk_buff *skb;
549 	u32 seq = info->nlh ? info->nlh->nlmsg_seq : 0;
550 	int err = -ENOBUFS;
551 
552 	skb = nlmsg_new(fib_nlmsg_size(fa->fa_info), GFP_KERNEL);
553 	if (!skb)
554 		goto errout;
555 
556 	fri.fi = fa->fa_info;
557 	fri.tb_id = tb_id;
558 	fri.dst = key;
559 	fri.dst_len = dst_len;
560 	fri.dscp = fa->fa_dscp;
561 	fri.type = fa->fa_type;
562 	fri.offload = READ_ONCE(fa->offload);
563 	fri.trap = READ_ONCE(fa->trap);
564 	fri.offload_failed = READ_ONCE(fa->offload_failed);
565 	err = fib_dump_info(skb, info->portid, seq, event, &fri, nlm_flags);
566 	if (err < 0) {
567 		/* -EMSGSIZE implies BUG in fib_nlmsg_size() */
568 		WARN_ON(err == -EMSGSIZE);
569 		kfree_skb(skb);
570 		goto errout;
571 	}
572 	rtnl_notify(skb, info->nl_net, info->portid, RTNLGRP_IPV4_ROUTE,
573 		    info->nlh, GFP_KERNEL);
574 	return;
575 errout:
576 	rtnl_set_sk_err(info->nl_net, RTNLGRP_IPV4_ROUTE, err);
577 }
578 
fib_detect_death(struct fib_info * fi,int order,struct fib_info ** last_resort,int * last_idx,int dflt)579 static int fib_detect_death(struct fib_info *fi, int order,
580 			    struct fib_info **last_resort, int *last_idx,
581 			    int dflt)
582 {
583 	const struct fib_nh_common *nhc = fib_info_nhc(fi, 0);
584 	struct neighbour *n;
585 	int state = NUD_NONE;
586 
587 	if (likely(nhc->nhc_gw_family == AF_INET))
588 		n = neigh_lookup(&arp_tbl, &nhc->nhc_gw.ipv4, nhc->nhc_dev);
589 	else if (nhc->nhc_gw_family == AF_INET6)
590 		n = neigh_lookup(ipv6_stub->nd_tbl, &nhc->nhc_gw.ipv6,
591 				 nhc->nhc_dev);
592 	else
593 		n = NULL;
594 
595 	if (n) {
596 		state = READ_ONCE(n->nud_state);
597 		neigh_release(n);
598 	} else {
599 		return 0;
600 	}
601 	if (state == NUD_REACHABLE)
602 		return 0;
603 	if ((state & NUD_VALID) && order != dflt)
604 		return 0;
605 	if ((state & NUD_VALID) ||
606 	    (*last_idx < 0 && order > dflt && state != NUD_INCOMPLETE)) {
607 		*last_resort = fi;
608 		*last_idx = order;
609 	}
610 	return 1;
611 }
612 
fib_nh_common_init(struct net * net,struct fib_nh_common * nhc,struct nlattr * encap,u16 encap_type,void * cfg,gfp_t gfp_flags,struct netlink_ext_ack * extack)613 int fib_nh_common_init(struct net *net, struct fib_nh_common *nhc,
614 		       struct nlattr *encap, u16 encap_type,
615 		       void *cfg, gfp_t gfp_flags,
616 		       struct netlink_ext_ack *extack)
617 {
618 	int err;
619 
620 	nhc->nhc_pcpu_rth_output = alloc_percpu_gfp(struct rtable __rcu *,
621 						    gfp_flags);
622 	if (!nhc->nhc_pcpu_rth_output)
623 		return -ENOMEM;
624 
625 	if (encap) {
626 		struct lwtunnel_state *lwtstate;
627 
628 		if (encap_type == LWTUNNEL_ENCAP_NONE) {
629 			NL_SET_ERR_MSG(extack, "LWT encap type not specified");
630 			err = -EINVAL;
631 			goto lwt_failure;
632 		}
633 		err = lwtunnel_build_state(net, encap_type, encap,
634 					   nhc->nhc_family, cfg, &lwtstate,
635 					   extack);
636 		if (err)
637 			goto lwt_failure;
638 
639 		nhc->nhc_lwtstate = lwtstate_get(lwtstate);
640 	}
641 
642 	return 0;
643 
644 lwt_failure:
645 	rt_fibinfo_free_cpus(nhc->nhc_pcpu_rth_output);
646 	nhc->nhc_pcpu_rth_output = NULL;
647 	return err;
648 }
649 EXPORT_SYMBOL_GPL(fib_nh_common_init);
650 
fib_nh_init(struct net * net,struct fib_nh * nh,struct fib_config * cfg,int nh_weight,struct netlink_ext_ack * extack)651 int fib_nh_init(struct net *net, struct fib_nh *nh,
652 		struct fib_config *cfg, int nh_weight,
653 		struct netlink_ext_ack *extack)
654 {
655 	int err;
656 
657 	nh->fib_nh_family = AF_INET;
658 
659 	err = fib_nh_common_init(net, &nh->nh_common, cfg->fc_encap,
660 				 cfg->fc_encap_type, cfg, GFP_KERNEL, extack);
661 	if (err)
662 		return err;
663 
664 	nh->fib_nh_oif = cfg->fc_oif;
665 	nh->fib_nh_gw_family = cfg->fc_gw_family;
666 	if (cfg->fc_gw_family == AF_INET)
667 		nh->fib_nh_gw4 = cfg->fc_gw4;
668 	else if (cfg->fc_gw_family == AF_INET6)
669 		nh->fib_nh_gw6 = cfg->fc_gw6;
670 
671 	nh->fib_nh_flags = cfg->fc_flags;
672 
673 #ifdef CONFIG_IP_ROUTE_CLASSID
674 	nh->nh_tclassid = cfg->fc_flow;
675 	if (nh->nh_tclassid)
676 		atomic_inc(&net->ipv4.fib_num_tclassid_users);
677 #endif
678 #ifdef CONFIG_IP_ROUTE_MULTIPATH
679 	nh->fib_nh_weight = nh_weight;
680 #endif
681 	return 0;
682 }
683 
684 #ifdef CONFIG_IP_ROUTE_MULTIPATH
685 
fib_count_nexthops(struct rtnexthop * rtnh,int remaining,struct netlink_ext_ack * extack)686 static int fib_count_nexthops(struct rtnexthop *rtnh, int remaining,
687 			      struct netlink_ext_ack *extack)
688 {
689 	int nhs = 0;
690 
691 	while (rtnh_ok(rtnh, remaining)) {
692 		nhs++;
693 		rtnh = rtnh_next(rtnh, &remaining);
694 	}
695 
696 	/* leftover implies invalid nexthop configuration, discard it */
697 	if (remaining > 0) {
698 		NL_SET_ERR_MSG(extack,
699 			       "Invalid nexthop configuration - extra data after nexthops");
700 		nhs = 0;
701 	}
702 
703 	return nhs;
704 }
705 
fib_gw_from_attr(__be32 * gw,struct nlattr * nla,struct netlink_ext_ack * extack)706 static int fib_gw_from_attr(__be32 *gw, struct nlattr *nla,
707 			    struct netlink_ext_ack *extack)
708 {
709 	if (nla_len(nla) < sizeof(*gw)) {
710 		NL_SET_ERR_MSG(extack, "Invalid IPv4 address in RTA_GATEWAY");
711 		return -EINVAL;
712 	}
713 
714 	*gw = nla_get_in_addr(nla);
715 
716 	return 0;
717 }
718 
719 /* only called when fib_nh is integrated into fib_info */
fib_get_nhs(struct fib_info * fi,struct rtnexthop * rtnh,int remaining,struct fib_config * cfg,struct netlink_ext_ack * extack)720 static int fib_get_nhs(struct fib_info *fi, struct rtnexthop *rtnh,
721 		       int remaining, struct fib_config *cfg,
722 		       struct netlink_ext_ack *extack)
723 {
724 	struct net *net = fi->fib_net;
725 	struct fib_config fib_cfg;
726 	struct fib_nh *nh;
727 	int ret;
728 
729 	change_nexthops(fi) {
730 		int attrlen;
731 
732 		memset(&fib_cfg, 0, sizeof(fib_cfg));
733 
734 		if (!rtnh_ok(rtnh, remaining)) {
735 			NL_SET_ERR_MSG(extack,
736 				       "Invalid nexthop configuration - extra data after nexthop");
737 			return -EINVAL;
738 		}
739 
740 		if (rtnh->rtnh_flags & (RTNH_F_DEAD | RTNH_F_LINKDOWN)) {
741 			NL_SET_ERR_MSG(extack,
742 				       "Invalid flags for nexthop - can not contain DEAD or LINKDOWN");
743 			return -EINVAL;
744 		}
745 
746 		fib_cfg.fc_flags = (cfg->fc_flags & ~0xFF) | rtnh->rtnh_flags;
747 		fib_cfg.fc_oif = rtnh->rtnh_ifindex;
748 
749 		attrlen = rtnh_attrlen(rtnh);
750 		if (attrlen > 0) {
751 			struct nlattr *nla, *nlav, *attrs = rtnh_attrs(rtnh);
752 
753 			nla = nla_find(attrs, attrlen, RTA_GATEWAY);
754 			nlav = nla_find(attrs, attrlen, RTA_VIA);
755 			if (nla && nlav) {
756 				NL_SET_ERR_MSG(extack,
757 					       "Nexthop configuration can not contain both GATEWAY and VIA");
758 				return -EINVAL;
759 			}
760 			if (nla) {
761 				ret = fib_gw_from_attr(&fib_cfg.fc_gw4, nla,
762 						       extack);
763 				if (ret)
764 					goto errout;
765 
766 				if (fib_cfg.fc_gw4)
767 					fib_cfg.fc_gw_family = AF_INET;
768 			} else if (nlav) {
769 				ret = fib_gw_from_via(&fib_cfg, nlav, extack);
770 				if (ret)
771 					goto errout;
772 			}
773 
774 			nla = nla_find(attrs, attrlen, RTA_FLOW);
775 			if (nla) {
776 				if (nla_len(nla) < sizeof(u32)) {
777 					NL_SET_ERR_MSG(extack, "Invalid RTA_FLOW");
778 					return -EINVAL;
779 				}
780 				fib_cfg.fc_flow = nla_get_u32(nla);
781 			}
782 
783 			fib_cfg.fc_encap = nla_find(attrs, attrlen, RTA_ENCAP);
784 			/* RTA_ENCAP_TYPE length checked in
785 			 * lwtunnel_valid_encap_type_attr
786 			 */
787 			nla = nla_find(attrs, attrlen, RTA_ENCAP_TYPE);
788 			if (nla)
789 				fib_cfg.fc_encap_type = nla_get_u16(nla);
790 		}
791 
792 		ret = fib_nh_init(net, nexthop_nh, &fib_cfg,
793 				  rtnh->rtnh_hops + 1, extack);
794 		if (ret)
795 			goto errout;
796 
797 		rtnh = rtnh_next(rtnh, &remaining);
798 	} endfor_nexthops(fi);
799 
800 	ret = -EINVAL;
801 	nh = fib_info_nh(fi, 0);
802 	if (cfg->fc_oif && nh->fib_nh_oif != cfg->fc_oif) {
803 		NL_SET_ERR_MSG(extack,
804 			       "Nexthop device index does not match RTA_OIF");
805 		goto errout;
806 	}
807 	if (cfg->fc_gw_family) {
808 		if (cfg->fc_gw_family != nh->fib_nh_gw_family ||
809 		    (cfg->fc_gw_family == AF_INET &&
810 		     nh->fib_nh_gw4 != cfg->fc_gw4) ||
811 		    (cfg->fc_gw_family == AF_INET6 &&
812 		     ipv6_addr_cmp(&nh->fib_nh_gw6, &cfg->fc_gw6))) {
813 			NL_SET_ERR_MSG(extack,
814 				       "Nexthop gateway does not match RTA_GATEWAY or RTA_VIA");
815 			goto errout;
816 		}
817 	}
818 #ifdef CONFIG_IP_ROUTE_CLASSID
819 	if (cfg->fc_flow && nh->nh_tclassid != cfg->fc_flow) {
820 		NL_SET_ERR_MSG(extack,
821 			       "Nexthop class id does not match RTA_FLOW");
822 		goto errout;
823 	}
824 #endif
825 	ret = 0;
826 errout:
827 	return ret;
828 }
829 
830 /* only called when fib_nh is integrated into fib_info */
fib_rebalance(struct fib_info * fi)831 static void fib_rebalance(struct fib_info *fi)
832 {
833 	int total;
834 	int w;
835 
836 	if (fib_info_num_path(fi) < 2)
837 		return;
838 
839 	total = 0;
840 	for_nexthops(fi) {
841 		if (nh->fib_nh_flags & RTNH_F_DEAD)
842 			continue;
843 
844 		if (ip_ignore_linkdown(nh->fib_nh_dev) &&
845 		    nh->fib_nh_flags & RTNH_F_LINKDOWN)
846 			continue;
847 
848 		total += nh->fib_nh_weight;
849 	} endfor_nexthops(fi);
850 
851 	w = 0;
852 	change_nexthops(fi) {
853 		int upper_bound;
854 
855 		if (nexthop_nh->fib_nh_flags & RTNH_F_DEAD) {
856 			upper_bound = -1;
857 		} else if (ip_ignore_linkdown(nexthop_nh->fib_nh_dev) &&
858 			   nexthop_nh->fib_nh_flags & RTNH_F_LINKDOWN) {
859 			upper_bound = -1;
860 		} else {
861 			w += nexthop_nh->fib_nh_weight;
862 			upper_bound = DIV_ROUND_CLOSEST_ULL((u64)w << 31,
863 							    total) - 1;
864 		}
865 
866 		atomic_set(&nexthop_nh->fib_nh_upper_bound, upper_bound);
867 	} endfor_nexthops(fi);
868 }
869 #else /* CONFIG_IP_ROUTE_MULTIPATH */
870 
fib_get_nhs(struct fib_info * fi,struct rtnexthop * rtnh,int remaining,struct fib_config * cfg,struct netlink_ext_ack * extack)871 static int fib_get_nhs(struct fib_info *fi, struct rtnexthop *rtnh,
872 		       int remaining, struct fib_config *cfg,
873 		       struct netlink_ext_ack *extack)
874 {
875 	NL_SET_ERR_MSG(extack, "Multipath support not enabled in kernel");
876 
877 	return -EINVAL;
878 }
879 
880 #define fib_rebalance(fi) do { } while (0)
881 
882 #endif /* CONFIG_IP_ROUTE_MULTIPATH */
883 
fib_encap_match(struct net * net,u16 encap_type,struct nlattr * encap,const struct fib_nh * nh,const struct fib_config * cfg,struct netlink_ext_ack * extack)884 static int fib_encap_match(struct net *net, u16 encap_type,
885 			   struct nlattr *encap,
886 			   const struct fib_nh *nh,
887 			   const struct fib_config *cfg,
888 			   struct netlink_ext_ack *extack)
889 {
890 	struct lwtunnel_state *lwtstate;
891 	int ret, result = 0;
892 
893 	if (encap_type == LWTUNNEL_ENCAP_NONE)
894 		return 0;
895 
896 	ret = lwtunnel_build_state(net, encap_type, encap, AF_INET,
897 				   cfg, &lwtstate, extack);
898 	if (!ret) {
899 		result = lwtunnel_cmp_encap(lwtstate, nh->fib_nh_lws);
900 		lwtstate_free(lwtstate);
901 	}
902 
903 	return result;
904 }
905 
fib_nh_match(struct net * net,struct fib_config * cfg,struct fib_info * fi,struct netlink_ext_ack * extack)906 int fib_nh_match(struct net *net, struct fib_config *cfg, struct fib_info *fi,
907 		 struct netlink_ext_ack *extack)
908 {
909 #ifdef CONFIG_IP_ROUTE_MULTIPATH
910 	struct rtnexthop *rtnh;
911 	int remaining;
912 #endif
913 
914 	if (cfg->fc_priority && cfg->fc_priority != fi->fib_priority)
915 		return 1;
916 
917 	if (cfg->fc_nh_id) {
918 		if (fi->nh && cfg->fc_nh_id == fi->nh->id)
919 			return 0;
920 		return 1;
921 	}
922 
923 	if (fi->nh) {
924 		if (cfg->fc_oif || cfg->fc_gw_family || cfg->fc_mp)
925 			return 1;
926 		return 0;
927 	}
928 
929 	if (cfg->fc_oif || cfg->fc_gw_family) {
930 		struct fib_nh *nh;
931 
932 		nh = fib_info_nh(fi, 0);
933 		if (cfg->fc_encap) {
934 			if (fib_encap_match(net, cfg->fc_encap_type,
935 					    cfg->fc_encap, nh, cfg, extack))
936 				return 1;
937 		}
938 #ifdef CONFIG_IP_ROUTE_CLASSID
939 		if (cfg->fc_flow &&
940 		    cfg->fc_flow != nh->nh_tclassid)
941 			return 1;
942 #endif
943 		if ((cfg->fc_oif && cfg->fc_oif != nh->fib_nh_oif) ||
944 		    (cfg->fc_gw_family &&
945 		     cfg->fc_gw_family != nh->fib_nh_gw_family))
946 			return 1;
947 
948 		if (cfg->fc_gw_family == AF_INET &&
949 		    cfg->fc_gw4 != nh->fib_nh_gw4)
950 			return 1;
951 
952 		if (cfg->fc_gw_family == AF_INET6 &&
953 		    ipv6_addr_cmp(&cfg->fc_gw6, &nh->fib_nh_gw6))
954 			return 1;
955 
956 		return 0;
957 	}
958 
959 #ifdef CONFIG_IP_ROUTE_MULTIPATH
960 	if (!cfg->fc_mp)
961 		return 0;
962 
963 	rtnh = cfg->fc_mp;
964 	remaining = cfg->fc_mp_len;
965 
966 	for_nexthops(fi) {
967 		int attrlen;
968 
969 		if (!rtnh_ok(rtnh, remaining))
970 			return -EINVAL;
971 
972 		if (rtnh->rtnh_ifindex && rtnh->rtnh_ifindex != nh->fib_nh_oif)
973 			return 1;
974 
975 		attrlen = rtnh_attrlen(rtnh);
976 		if (attrlen > 0) {
977 			struct nlattr *nla, *nlav, *attrs = rtnh_attrs(rtnh);
978 			int err;
979 
980 			nla = nla_find(attrs, attrlen, RTA_GATEWAY);
981 			nlav = nla_find(attrs, attrlen, RTA_VIA);
982 			if (nla && nlav) {
983 				NL_SET_ERR_MSG(extack,
984 					       "Nexthop configuration can not contain both GATEWAY and VIA");
985 				return -EINVAL;
986 			}
987 
988 			if (nla) {
989 				__be32 gw;
990 
991 				err = fib_gw_from_attr(&gw, nla, extack);
992 				if (err)
993 					return err;
994 
995 				if (nh->fib_nh_gw_family != AF_INET ||
996 				    gw != nh->fib_nh_gw4)
997 					return 1;
998 			} else if (nlav) {
999 				struct fib_config cfg2;
1000 
1001 				err = fib_gw_from_via(&cfg2, nlav, extack);
1002 				if (err)
1003 					return err;
1004 
1005 				switch (nh->fib_nh_gw_family) {
1006 				case AF_INET:
1007 					if (cfg2.fc_gw_family != AF_INET ||
1008 					    cfg2.fc_gw4 != nh->fib_nh_gw4)
1009 						return 1;
1010 					break;
1011 				case AF_INET6:
1012 					if (cfg2.fc_gw_family != AF_INET6 ||
1013 					    ipv6_addr_cmp(&cfg2.fc_gw6,
1014 							  &nh->fib_nh_gw6))
1015 						return 1;
1016 					break;
1017 				}
1018 			}
1019 
1020 #ifdef CONFIG_IP_ROUTE_CLASSID
1021 			nla = nla_find(attrs, attrlen, RTA_FLOW);
1022 			if (nla) {
1023 				if (nla_len(nla) < sizeof(u32)) {
1024 					NL_SET_ERR_MSG(extack, "Invalid RTA_FLOW");
1025 					return -EINVAL;
1026 				}
1027 				if (nla_get_u32(nla) != nh->nh_tclassid)
1028 					return 1;
1029 			}
1030 #endif
1031 		}
1032 
1033 		rtnh = rtnh_next(rtnh, &remaining);
1034 	} endfor_nexthops(fi);
1035 #endif
1036 	return 0;
1037 }
1038 
fib_metrics_match(struct fib_config * cfg,struct fib_info * fi)1039 bool fib_metrics_match(struct fib_config *cfg, struct fib_info *fi)
1040 {
1041 	struct nlattr *nla;
1042 	int remaining;
1043 
1044 	if (!cfg->fc_mx)
1045 		return true;
1046 
1047 	nla_for_each_attr(nla, cfg->fc_mx, cfg->fc_mx_len, remaining) {
1048 		int type = nla_type(nla);
1049 		u32 fi_val, val;
1050 
1051 		if (!type)
1052 			continue;
1053 		if (type > RTAX_MAX)
1054 			return false;
1055 
1056 		type = array_index_nospec(type, RTAX_MAX + 1);
1057 		if (type == RTAX_CC_ALGO) {
1058 			char tmp[TCP_CA_NAME_MAX];
1059 			bool ecn_ca = false;
1060 
1061 			nla_strscpy(tmp, nla, sizeof(tmp));
1062 			val = tcp_ca_get_key_by_name(tmp, &ecn_ca);
1063 		} else {
1064 			if (nla_len(nla) != sizeof(u32))
1065 				return false;
1066 			val = nla_get_u32(nla);
1067 		}
1068 
1069 		fi_val = fi->fib_metrics->metrics[type - 1];
1070 		if (type == RTAX_FEATURES)
1071 			fi_val &= ~DST_FEATURE_ECN_CA;
1072 
1073 		if (fi_val != val)
1074 			return false;
1075 	}
1076 
1077 	return true;
1078 }
1079 
fib_check_nh_v6_gw(struct net * net,struct fib_nh * nh,u32 table,struct netlink_ext_ack * extack)1080 static int fib_check_nh_v6_gw(struct net *net, struct fib_nh *nh,
1081 			      u32 table, struct netlink_ext_ack *extack)
1082 {
1083 	struct fib6_config cfg = {
1084 		.fc_table = table,
1085 		.fc_flags = nh->fib_nh_flags | RTF_GATEWAY,
1086 		.fc_ifindex = nh->fib_nh_oif,
1087 		.fc_gateway = nh->fib_nh_gw6,
1088 	};
1089 	struct fib6_nh fib6_nh = {};
1090 	int err;
1091 
1092 	err = ipv6_stub->fib6_nh_init(net, &fib6_nh, &cfg, GFP_KERNEL, extack);
1093 	if (!err) {
1094 		nh->fib_nh_dev = fib6_nh.fib_nh_dev;
1095 		netdev_hold(nh->fib_nh_dev, &nh->fib_nh_dev_tracker,
1096 			    GFP_KERNEL);
1097 		nh->fib_nh_oif = nh->fib_nh_dev->ifindex;
1098 		nh->fib_nh_scope = RT_SCOPE_LINK;
1099 
1100 		ipv6_stub->fib6_nh_release(&fib6_nh);
1101 	}
1102 
1103 	return err;
1104 }
1105 
1106 /*
1107  * Picture
1108  * -------
1109  *
1110  * Semantics of nexthop is very messy by historical reasons.
1111  * We have to take into account, that:
1112  * a) gateway can be actually local interface address,
1113  *    so that gatewayed route is direct.
1114  * b) gateway must be on-link address, possibly
1115  *    described not by an ifaddr, but also by a direct route.
1116  * c) If both gateway and interface are specified, they should not
1117  *    contradict.
1118  * d) If we use tunnel routes, gateway could be not on-link.
1119  *
1120  * Attempt to reconcile all of these (alas, self-contradictory) conditions
1121  * results in pretty ugly and hairy code with obscure logic.
1122  *
1123  * I chose to generalized it instead, so that the size
1124  * of code does not increase practically, but it becomes
1125  * much more general.
1126  * Every prefix is assigned a "scope" value: "host" is local address,
1127  * "link" is direct route,
1128  * [ ... "site" ... "interior" ... ]
1129  * and "universe" is true gateway route with global meaning.
1130  *
1131  * Every prefix refers to a set of "nexthop"s (gw, oif),
1132  * where gw must have narrower scope. This recursion stops
1133  * when gw has LOCAL scope or if "nexthop" is declared ONLINK,
1134  * which means that gw is forced to be on link.
1135  *
1136  * Code is still hairy, but now it is apparently logically
1137  * consistent and very flexible. F.e. as by-product it allows
1138  * to co-exists in peace independent exterior and interior
1139  * routing processes.
1140  *
1141  * Normally it looks as following.
1142  *
1143  * {universe prefix}  -> (gw, oif) [scope link]
1144  *		  |
1145  *		  |-> {link prefix} -> (gw, oif) [scope local]
1146  *					|
1147  *					|-> {local prefix} (terminal node)
1148  */
fib_check_nh_v4_gw(struct net * net,struct fib_nh * nh,u32 table,u8 scope,struct netlink_ext_ack * extack)1149 static int fib_check_nh_v4_gw(struct net *net, struct fib_nh *nh, u32 table,
1150 			      u8 scope, struct netlink_ext_ack *extack)
1151 {
1152 	struct net_device *dev;
1153 	struct fib_result res;
1154 	int err = 0;
1155 
1156 	if (nh->fib_nh_flags & RTNH_F_ONLINK) {
1157 		unsigned int addr_type;
1158 
1159 		if (scope >= RT_SCOPE_LINK) {
1160 			NL_SET_ERR_MSG(extack, "Nexthop has invalid scope");
1161 			return -EINVAL;
1162 		}
1163 		dev = __dev_get_by_index(net, nh->fib_nh_oif);
1164 		if (!dev) {
1165 			NL_SET_ERR_MSG(extack, "Nexthop device required for onlink");
1166 			return -ENODEV;
1167 		}
1168 		if (!(dev->flags & IFF_UP)) {
1169 			NL_SET_ERR_MSG(extack, "Nexthop device is not up");
1170 			return -ENETDOWN;
1171 		}
1172 		addr_type = inet_addr_type_dev_table(net, dev, nh->fib_nh_gw4);
1173 		if (addr_type != RTN_UNICAST) {
1174 			NL_SET_ERR_MSG(extack, "Nexthop has invalid gateway");
1175 			return -EINVAL;
1176 		}
1177 		if (!netif_carrier_ok(dev))
1178 			nh->fib_nh_flags |= RTNH_F_LINKDOWN;
1179 		nh->fib_nh_dev = dev;
1180 		netdev_hold(dev, &nh->fib_nh_dev_tracker, GFP_ATOMIC);
1181 		nh->fib_nh_scope = RT_SCOPE_LINK;
1182 		return 0;
1183 	}
1184 	rcu_read_lock();
1185 	{
1186 		struct fib_table *tbl = NULL;
1187 		struct flowi4 fl4 = {
1188 			.daddr = nh->fib_nh_gw4,
1189 			.flowi4_scope = scope + 1,
1190 			.flowi4_oif = nh->fib_nh_oif,
1191 			.flowi4_iif = LOOPBACK_IFINDEX,
1192 		};
1193 
1194 		/* It is not necessary, but requires a bit of thinking */
1195 		if (fl4.flowi4_scope < RT_SCOPE_LINK)
1196 			fl4.flowi4_scope = RT_SCOPE_LINK;
1197 
1198 		if (table && table != RT_TABLE_MAIN)
1199 			tbl = fib_get_table(net, table);
1200 
1201 		if (tbl)
1202 			err = fib_table_lookup(tbl, &fl4, &res,
1203 					       FIB_LOOKUP_IGNORE_LINKSTATE |
1204 					       FIB_LOOKUP_NOREF);
1205 
1206 		/* on error or if no table given do full lookup. This
1207 		 * is needed for example when nexthops are in the local
1208 		 * table rather than the given table
1209 		 */
1210 		if (!tbl || err) {
1211 			err = fib_lookup(net, &fl4, &res,
1212 					 FIB_LOOKUP_IGNORE_LINKSTATE);
1213 		}
1214 
1215 		if (err) {
1216 			NL_SET_ERR_MSG(extack, "Nexthop has invalid gateway");
1217 			goto out;
1218 		}
1219 	}
1220 
1221 	err = -EINVAL;
1222 	if (res.type != RTN_UNICAST && res.type != RTN_LOCAL) {
1223 		NL_SET_ERR_MSG(extack, "Nexthop has invalid gateway");
1224 		goto out;
1225 	}
1226 	nh->fib_nh_scope = res.scope;
1227 	nh->fib_nh_oif = FIB_RES_OIF(res);
1228 	nh->fib_nh_dev = dev = FIB_RES_DEV(res);
1229 	if (!dev) {
1230 		NL_SET_ERR_MSG(extack,
1231 			       "No egress device for nexthop gateway");
1232 		goto out;
1233 	}
1234 	netdev_hold(dev, &nh->fib_nh_dev_tracker, GFP_ATOMIC);
1235 	if (!netif_carrier_ok(dev))
1236 		nh->fib_nh_flags |= RTNH_F_LINKDOWN;
1237 	err = (dev->flags & IFF_UP) ? 0 : -ENETDOWN;
1238 out:
1239 	rcu_read_unlock();
1240 	return err;
1241 }
1242 
fib_check_nh_nongw(struct net * net,struct fib_nh * nh,struct netlink_ext_ack * extack)1243 static int fib_check_nh_nongw(struct net *net, struct fib_nh *nh,
1244 			      struct netlink_ext_ack *extack)
1245 {
1246 	struct in_device *in_dev;
1247 	int err;
1248 
1249 	if (nh->fib_nh_flags & (RTNH_F_PERVASIVE | RTNH_F_ONLINK)) {
1250 		NL_SET_ERR_MSG(extack,
1251 			       "Invalid flags for nexthop - PERVASIVE and ONLINK can not be set");
1252 		return -EINVAL;
1253 	}
1254 
1255 	rcu_read_lock();
1256 
1257 	err = -ENODEV;
1258 	in_dev = inetdev_by_index(net, nh->fib_nh_oif);
1259 	if (!in_dev)
1260 		goto out;
1261 	err = -ENETDOWN;
1262 	if (!(in_dev->dev->flags & IFF_UP)) {
1263 		NL_SET_ERR_MSG(extack, "Device for nexthop is not up");
1264 		goto out;
1265 	}
1266 
1267 	nh->fib_nh_dev = in_dev->dev;
1268 	netdev_hold(nh->fib_nh_dev, &nh->fib_nh_dev_tracker, GFP_ATOMIC);
1269 	nh->fib_nh_scope = RT_SCOPE_HOST;
1270 	if (!netif_carrier_ok(nh->fib_nh_dev))
1271 		nh->fib_nh_flags |= RTNH_F_LINKDOWN;
1272 	err = 0;
1273 out:
1274 	rcu_read_unlock();
1275 	return err;
1276 }
1277 
fib_check_nh(struct net * net,struct fib_nh * nh,u32 table,u8 scope,struct netlink_ext_ack * extack)1278 int fib_check_nh(struct net *net, struct fib_nh *nh, u32 table, u8 scope,
1279 		 struct netlink_ext_ack *extack)
1280 {
1281 	int err;
1282 
1283 	if (nh->fib_nh_gw_family == AF_INET)
1284 		err = fib_check_nh_v4_gw(net, nh, table, scope, extack);
1285 	else if (nh->fib_nh_gw_family == AF_INET6)
1286 		err = fib_check_nh_v6_gw(net, nh, table, extack);
1287 	else
1288 		err = fib_check_nh_nongw(net, nh, extack);
1289 
1290 	return err;
1291 }
1292 
fib_info_update_nhc_saddr(struct net * net,struct fib_nh_common * nhc,unsigned char scope)1293 __be32 fib_info_update_nhc_saddr(struct net *net, struct fib_nh_common *nhc,
1294 				 unsigned char scope)
1295 {
1296 	struct fib_nh *nh;
1297 	__be32 saddr;
1298 
1299 	if (nhc->nhc_family != AF_INET)
1300 		return inet_select_addr(nhc->nhc_dev, 0, scope);
1301 
1302 	nh = container_of(nhc, struct fib_nh, nh_common);
1303 	saddr = inet_select_addr(nh->fib_nh_dev, nh->fib_nh_gw4, scope);
1304 
1305 	WRITE_ONCE(nh->nh_saddr, saddr);
1306 	WRITE_ONCE(nh->nh_saddr_genid, atomic_read(&net->ipv4.dev_addr_genid));
1307 
1308 	return saddr;
1309 }
1310 
fib_result_prefsrc(struct net * net,struct fib_result * res)1311 __be32 fib_result_prefsrc(struct net *net, struct fib_result *res)
1312 {
1313 	struct fib_nh_common *nhc = res->nhc;
1314 
1315 	if (res->fi->fib_prefsrc)
1316 		return res->fi->fib_prefsrc;
1317 
1318 	if (nhc->nhc_family == AF_INET) {
1319 		struct fib_nh *nh;
1320 
1321 		nh = container_of(nhc, struct fib_nh, nh_common);
1322 		if (READ_ONCE(nh->nh_saddr_genid) ==
1323 		    atomic_read(&net->ipv4.dev_addr_genid))
1324 			return READ_ONCE(nh->nh_saddr);
1325 	}
1326 
1327 	return fib_info_update_nhc_saddr(net, nhc, res->fi->fib_scope);
1328 }
1329 
fib_valid_prefsrc(struct fib_config * cfg,__be32 fib_prefsrc)1330 static bool fib_valid_prefsrc(struct fib_config *cfg, __be32 fib_prefsrc)
1331 {
1332 	if (cfg->fc_type != RTN_LOCAL || !cfg->fc_dst ||
1333 	    fib_prefsrc != cfg->fc_dst) {
1334 		u32 tb_id = cfg->fc_table;
1335 		int rc;
1336 
1337 		if (tb_id == RT_TABLE_MAIN)
1338 			tb_id = RT_TABLE_LOCAL;
1339 
1340 		rc = inet_addr_type_table(cfg->fc_nlinfo.nl_net,
1341 					  fib_prefsrc, tb_id);
1342 
1343 		if (rc != RTN_LOCAL && tb_id != RT_TABLE_LOCAL) {
1344 			rc = inet_addr_type_table(cfg->fc_nlinfo.nl_net,
1345 						  fib_prefsrc, RT_TABLE_LOCAL);
1346 		}
1347 
1348 		if (rc != RTN_LOCAL)
1349 			return false;
1350 	}
1351 	return true;
1352 }
1353 
fib_create_info(struct fib_config * cfg,struct netlink_ext_ack * extack)1354 struct fib_info *fib_create_info(struct fib_config *cfg,
1355 				 struct netlink_ext_ack *extack)
1356 {
1357 	int err;
1358 	struct fib_info *fi = NULL;
1359 	struct nexthop *nh = NULL;
1360 	struct fib_info *ofi;
1361 	int nhs = 1;
1362 	struct net *net = cfg->fc_nlinfo.nl_net;
1363 
1364 	ASSERT_RTNL();
1365 	if (cfg->fc_type > RTN_MAX)
1366 		goto err_inval;
1367 
1368 	/* Fast check to catch the most weird cases */
1369 	if (fib_props[cfg->fc_type].scope > cfg->fc_scope) {
1370 		NL_SET_ERR_MSG(extack, "Invalid scope");
1371 		goto err_inval;
1372 	}
1373 
1374 	if (cfg->fc_flags & (RTNH_F_DEAD | RTNH_F_LINKDOWN)) {
1375 		NL_SET_ERR_MSG(extack,
1376 			       "Invalid rtm_flags - can not contain DEAD or LINKDOWN");
1377 		goto err_inval;
1378 	}
1379 
1380 	if (cfg->fc_nh_id) {
1381 		if (!cfg->fc_mx) {
1382 			fi = fib_find_info_nh(net, cfg);
1383 			if (fi) {
1384 				refcount_inc(&fi->fib_treeref);
1385 				return fi;
1386 			}
1387 		}
1388 
1389 		nh = nexthop_find_by_id(net, cfg->fc_nh_id);
1390 		if (!nh) {
1391 			NL_SET_ERR_MSG(extack, "Nexthop id does not exist");
1392 			goto err_inval;
1393 		}
1394 		nhs = 0;
1395 	}
1396 
1397 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1398 	if (cfg->fc_mp) {
1399 		nhs = fib_count_nexthops(cfg->fc_mp, cfg->fc_mp_len, extack);
1400 		if (nhs == 0)
1401 			goto err_inval;
1402 	}
1403 #endif
1404 
1405 	fib_info_hash_grow(net);
1406 
1407 	fi = kzalloc(struct_size(fi, fib_nh, nhs), GFP_KERNEL);
1408 	if (!fi) {
1409 		err = -ENOBUFS;
1410 		goto failure;
1411 	}
1412 
1413 	fi->fib_metrics = ip_fib_metrics_init(cfg->fc_mx, cfg->fc_mx_len, extack);
1414 	if (IS_ERR(fi->fib_metrics)) {
1415 		err = PTR_ERR(fi->fib_metrics);
1416 		kfree(fi);
1417 		return ERR_PTR(err);
1418 	}
1419 
1420 	fi->fib_net = net;
1421 	fi->fib_protocol = cfg->fc_protocol;
1422 	fi->fib_scope = cfg->fc_scope;
1423 	fi->fib_flags = cfg->fc_flags;
1424 	fi->fib_priority = cfg->fc_priority;
1425 	fi->fib_prefsrc = cfg->fc_prefsrc;
1426 	fi->fib_type = cfg->fc_type;
1427 	fi->fib_tb_id = cfg->fc_table;
1428 
1429 	fi->fib_nhs = nhs;
1430 	if (nh) {
1431 		if (!nexthop_get(nh)) {
1432 			NL_SET_ERR_MSG(extack, "Nexthop has been deleted");
1433 			err = -EINVAL;
1434 		} else {
1435 			err = 0;
1436 			fi->nh = nh;
1437 		}
1438 	} else {
1439 		change_nexthops(fi) {
1440 			nexthop_nh->nh_parent = fi;
1441 		} endfor_nexthops(fi)
1442 
1443 		if (cfg->fc_mp)
1444 			err = fib_get_nhs(fi, cfg->fc_mp, cfg->fc_mp_len, cfg,
1445 					  extack);
1446 		else
1447 			err = fib_nh_init(net, fi->fib_nh, cfg, 1, extack);
1448 	}
1449 
1450 	if (err != 0)
1451 		goto failure;
1452 
1453 	if (fib_props[cfg->fc_type].error) {
1454 		if (cfg->fc_gw_family || cfg->fc_oif || cfg->fc_mp) {
1455 			NL_SET_ERR_MSG(extack,
1456 				       "Gateway, device and multipath can not be specified for this route type");
1457 			goto err_inval;
1458 		}
1459 		goto link_it;
1460 	} else {
1461 		switch (cfg->fc_type) {
1462 		case RTN_UNICAST:
1463 		case RTN_LOCAL:
1464 		case RTN_BROADCAST:
1465 		case RTN_ANYCAST:
1466 		case RTN_MULTICAST:
1467 			break;
1468 		default:
1469 			NL_SET_ERR_MSG(extack, "Invalid route type");
1470 			goto err_inval;
1471 		}
1472 	}
1473 
1474 	if (cfg->fc_scope > RT_SCOPE_HOST) {
1475 		NL_SET_ERR_MSG(extack, "Invalid scope");
1476 		goto err_inval;
1477 	}
1478 
1479 	if (fi->nh) {
1480 		err = fib_check_nexthop(fi->nh, cfg->fc_scope, extack);
1481 		if (err)
1482 			goto failure;
1483 	} else if (cfg->fc_scope == RT_SCOPE_HOST) {
1484 		struct fib_nh *nh = fi->fib_nh;
1485 
1486 		/* Local address is added. */
1487 		if (nhs != 1) {
1488 			NL_SET_ERR_MSG(extack,
1489 				       "Route with host scope can not have multiple nexthops");
1490 			goto err_inval;
1491 		}
1492 		if (nh->fib_nh_gw_family) {
1493 			NL_SET_ERR_MSG(extack,
1494 				       "Route with host scope can not have a gateway");
1495 			goto err_inval;
1496 		}
1497 		nh->fib_nh_scope = RT_SCOPE_NOWHERE;
1498 		nh->fib_nh_dev = dev_get_by_index(net, nh->fib_nh_oif);
1499 		err = -ENODEV;
1500 		if (!nh->fib_nh_dev)
1501 			goto failure;
1502 		netdev_tracker_alloc(nh->fib_nh_dev, &nh->fib_nh_dev_tracker,
1503 				     GFP_KERNEL);
1504 	} else {
1505 		int linkdown = 0;
1506 
1507 		change_nexthops(fi) {
1508 			err = fib_check_nh(cfg->fc_nlinfo.nl_net, nexthop_nh,
1509 					   cfg->fc_table, cfg->fc_scope,
1510 					   extack);
1511 			if (err != 0)
1512 				goto failure;
1513 			if (nexthop_nh->fib_nh_flags & RTNH_F_LINKDOWN)
1514 				linkdown++;
1515 		} endfor_nexthops(fi)
1516 		if (linkdown == fi->fib_nhs)
1517 			fi->fib_flags |= RTNH_F_LINKDOWN;
1518 	}
1519 
1520 	if (fi->fib_prefsrc && !fib_valid_prefsrc(cfg, fi->fib_prefsrc)) {
1521 		NL_SET_ERR_MSG(extack, "Invalid prefsrc address");
1522 		goto err_inval;
1523 	}
1524 
1525 	if (!fi->nh) {
1526 		change_nexthops(fi) {
1527 			fib_info_update_nhc_saddr(net, &nexthop_nh->nh_common,
1528 						  fi->fib_scope);
1529 			if (nexthop_nh->fib_nh_gw_family == AF_INET6)
1530 				fi->fib_nh_is_v6 = true;
1531 		} endfor_nexthops(fi)
1532 
1533 		fib_rebalance(fi);
1534 	}
1535 
1536 link_it:
1537 	ofi = fib_find_info(fi);
1538 	if (ofi) {
1539 		/* fib_table_lookup() should not see @fi yet. */
1540 		fi->fib_dead = 1;
1541 		free_fib_info(fi);
1542 		refcount_inc(&ofi->fib_treeref);
1543 		return ofi;
1544 	}
1545 
1546 	refcount_set(&fi->fib_treeref, 1);
1547 	refcount_set(&fi->fib_clntref, 1);
1548 
1549 	net->ipv4.fib_info_cnt++;
1550 	hlist_add_head(&fi->fib_hash, fib_info_hash_bucket(fi));
1551 
1552 	if (fi->fib_prefsrc) {
1553 		struct hlist_head *head;
1554 
1555 		head = fib_info_laddrhash_bucket(net, fi->fib_prefsrc);
1556 		hlist_add_head(&fi->fib_lhash, head);
1557 	}
1558 	if (fi->nh) {
1559 		list_add(&fi->nh_list, &nh->fi_list);
1560 	} else {
1561 		change_nexthops(fi) {
1562 			struct hlist_head *head;
1563 
1564 			if (!nexthop_nh->fib_nh_dev)
1565 				continue;
1566 			head = fib_nh_head(nexthop_nh->fib_nh_dev);
1567 			hlist_add_head_rcu(&nexthop_nh->nh_hash, head);
1568 		} endfor_nexthops(fi)
1569 	}
1570 	return fi;
1571 
1572 err_inval:
1573 	err = -EINVAL;
1574 
1575 failure:
1576 	if (fi) {
1577 		/* fib_table_lookup() should not see @fi yet. */
1578 		fi->fib_dead = 1;
1579 		free_fib_info(fi);
1580 	}
1581 
1582 	return ERR_PTR(err);
1583 }
1584 
fib_nexthop_info(struct sk_buff * skb,const struct fib_nh_common * nhc,u8 rt_family,unsigned char * flags,bool skip_oif)1585 int fib_nexthop_info(struct sk_buff *skb, const struct fib_nh_common *nhc,
1586 		     u8 rt_family, unsigned char *flags, bool skip_oif)
1587 {
1588 	if (nhc->nhc_flags & RTNH_F_DEAD)
1589 		*flags |= RTNH_F_DEAD;
1590 
1591 	if (nhc->nhc_flags & RTNH_F_LINKDOWN) {
1592 		*flags |= RTNH_F_LINKDOWN;
1593 
1594 		rcu_read_lock();
1595 		switch (nhc->nhc_family) {
1596 		case AF_INET:
1597 			if (ip_ignore_linkdown(nhc->nhc_dev))
1598 				*flags |= RTNH_F_DEAD;
1599 			break;
1600 		case AF_INET6:
1601 			if (ip6_ignore_linkdown(nhc->nhc_dev))
1602 				*flags |= RTNH_F_DEAD;
1603 			break;
1604 		}
1605 		rcu_read_unlock();
1606 	}
1607 
1608 	switch (nhc->nhc_gw_family) {
1609 	case AF_INET:
1610 		if (nla_put_in_addr(skb, RTA_GATEWAY, nhc->nhc_gw.ipv4))
1611 			goto nla_put_failure;
1612 		break;
1613 	case AF_INET6:
1614 		/* if gateway family does not match nexthop family
1615 		 * gateway is encoded as RTA_VIA
1616 		 */
1617 		if (rt_family != nhc->nhc_gw_family) {
1618 			int alen = sizeof(struct in6_addr);
1619 			struct nlattr *nla;
1620 			struct rtvia *via;
1621 
1622 			nla = nla_reserve(skb, RTA_VIA, alen + 2);
1623 			if (!nla)
1624 				goto nla_put_failure;
1625 
1626 			via = nla_data(nla);
1627 			via->rtvia_family = AF_INET6;
1628 			memcpy(via->rtvia_addr, &nhc->nhc_gw.ipv6, alen);
1629 		} else if (nla_put_in6_addr(skb, RTA_GATEWAY,
1630 					    &nhc->nhc_gw.ipv6) < 0) {
1631 			goto nla_put_failure;
1632 		}
1633 		break;
1634 	}
1635 
1636 	*flags |= (nhc->nhc_flags &
1637 		   (RTNH_F_ONLINK | RTNH_F_OFFLOAD | RTNH_F_TRAP));
1638 
1639 	if (!skip_oif && nhc->nhc_dev &&
1640 	    nla_put_u32(skb, RTA_OIF, nhc->nhc_dev->ifindex))
1641 		goto nla_put_failure;
1642 
1643 	if (nhc->nhc_lwtstate &&
1644 	    lwtunnel_fill_encap(skb, nhc->nhc_lwtstate,
1645 				RTA_ENCAP, RTA_ENCAP_TYPE) < 0)
1646 		goto nla_put_failure;
1647 
1648 	return 0;
1649 
1650 nla_put_failure:
1651 	return -EMSGSIZE;
1652 }
1653 EXPORT_SYMBOL_GPL(fib_nexthop_info);
1654 
1655 #if IS_ENABLED(CONFIG_IP_ROUTE_MULTIPATH) || IS_ENABLED(CONFIG_IPV6)
fib_add_nexthop(struct sk_buff * skb,const struct fib_nh_common * nhc,int nh_weight,u8 rt_family,u32 nh_tclassid)1656 int fib_add_nexthop(struct sk_buff *skb, const struct fib_nh_common *nhc,
1657 		    int nh_weight, u8 rt_family, u32 nh_tclassid)
1658 {
1659 	const struct net_device *dev = nhc->nhc_dev;
1660 	struct rtnexthop *rtnh;
1661 	unsigned char flags = 0;
1662 
1663 	rtnh = nla_reserve_nohdr(skb, sizeof(*rtnh));
1664 	if (!rtnh)
1665 		goto nla_put_failure;
1666 
1667 	rtnh->rtnh_hops = nh_weight - 1;
1668 	rtnh->rtnh_ifindex = dev ? dev->ifindex : 0;
1669 
1670 	if (fib_nexthop_info(skb, nhc, rt_family, &flags, true) < 0)
1671 		goto nla_put_failure;
1672 
1673 	rtnh->rtnh_flags = flags;
1674 
1675 	if (nh_tclassid && nla_put_u32(skb, RTA_FLOW, nh_tclassid))
1676 		goto nla_put_failure;
1677 
1678 	/* length of rtnetlink header + attributes */
1679 	rtnh->rtnh_len = nlmsg_get_pos(skb) - (void *)rtnh;
1680 
1681 	return 0;
1682 
1683 nla_put_failure:
1684 	return -EMSGSIZE;
1685 }
1686 EXPORT_SYMBOL_GPL(fib_add_nexthop);
1687 #endif
1688 
1689 #ifdef CONFIG_IP_ROUTE_MULTIPATH
fib_add_multipath(struct sk_buff * skb,struct fib_info * fi)1690 static int fib_add_multipath(struct sk_buff *skb, struct fib_info *fi)
1691 {
1692 	struct nlattr *mp;
1693 
1694 	mp = nla_nest_start_noflag(skb, RTA_MULTIPATH);
1695 	if (!mp)
1696 		goto nla_put_failure;
1697 
1698 	if (unlikely(fi->nh)) {
1699 		if (nexthop_mpath_fill_node(skb, fi->nh, AF_INET) < 0)
1700 			goto nla_put_failure;
1701 		goto mp_end;
1702 	}
1703 
1704 	for_nexthops(fi) {
1705 		u32 nh_tclassid = 0;
1706 #ifdef CONFIG_IP_ROUTE_CLASSID
1707 		nh_tclassid = nh->nh_tclassid;
1708 #endif
1709 		if (fib_add_nexthop(skb, &nh->nh_common, nh->fib_nh_weight,
1710 				    AF_INET, nh_tclassid) < 0)
1711 			goto nla_put_failure;
1712 	} endfor_nexthops(fi);
1713 
1714 mp_end:
1715 	nla_nest_end(skb, mp);
1716 
1717 	return 0;
1718 
1719 nla_put_failure:
1720 	return -EMSGSIZE;
1721 }
1722 #else
fib_add_multipath(struct sk_buff * skb,struct fib_info * fi)1723 static int fib_add_multipath(struct sk_buff *skb, struct fib_info *fi)
1724 {
1725 	return 0;
1726 }
1727 #endif
1728 
fib_dump_info(struct sk_buff * skb,u32 portid,u32 seq,int event,const struct fib_rt_info * fri,unsigned int flags)1729 int fib_dump_info(struct sk_buff *skb, u32 portid, u32 seq, int event,
1730 		  const struct fib_rt_info *fri, unsigned int flags)
1731 {
1732 	unsigned int nhs = fib_info_num_path(fri->fi);
1733 	struct fib_info *fi = fri->fi;
1734 	u32 tb_id = fri->tb_id;
1735 	struct nlmsghdr *nlh;
1736 	struct rtmsg *rtm;
1737 
1738 	nlh = nlmsg_put(skb, portid, seq, event, sizeof(*rtm), flags);
1739 	if (!nlh)
1740 		return -EMSGSIZE;
1741 
1742 	rtm = nlmsg_data(nlh);
1743 	rtm->rtm_family = AF_INET;
1744 	rtm->rtm_dst_len = fri->dst_len;
1745 	rtm->rtm_src_len = 0;
1746 	rtm->rtm_tos = inet_dscp_to_dsfield(fri->dscp);
1747 	if (tb_id < 256)
1748 		rtm->rtm_table = tb_id;
1749 	else
1750 		rtm->rtm_table = RT_TABLE_COMPAT;
1751 	if (nla_put_u32(skb, RTA_TABLE, tb_id))
1752 		goto nla_put_failure;
1753 	rtm->rtm_type = fri->type;
1754 	rtm->rtm_flags = fi->fib_flags;
1755 	rtm->rtm_scope = fi->fib_scope;
1756 	rtm->rtm_protocol = fi->fib_protocol;
1757 
1758 	if (rtm->rtm_dst_len &&
1759 	    nla_put_in_addr(skb, RTA_DST, fri->dst))
1760 		goto nla_put_failure;
1761 	if (fi->fib_priority &&
1762 	    nla_put_u32(skb, RTA_PRIORITY, fi->fib_priority))
1763 		goto nla_put_failure;
1764 	if (rtnetlink_put_metrics(skb, fi->fib_metrics->metrics) < 0)
1765 		goto nla_put_failure;
1766 
1767 	if (fi->fib_prefsrc &&
1768 	    nla_put_in_addr(skb, RTA_PREFSRC, fi->fib_prefsrc))
1769 		goto nla_put_failure;
1770 
1771 	if (fi->nh) {
1772 		if (nla_put_u32(skb, RTA_NH_ID, fi->nh->id))
1773 			goto nla_put_failure;
1774 		if (nexthop_is_blackhole(fi->nh))
1775 			rtm->rtm_type = RTN_BLACKHOLE;
1776 		if (!READ_ONCE(fi->fib_net->ipv4.sysctl_nexthop_compat_mode))
1777 			goto offload;
1778 	}
1779 
1780 	if (nhs == 1) {
1781 		const struct fib_nh_common *nhc = fib_info_nhc(fi, 0);
1782 		unsigned char flags = 0;
1783 
1784 		if (fib_nexthop_info(skb, nhc, AF_INET, &flags, false) < 0)
1785 			goto nla_put_failure;
1786 
1787 		rtm->rtm_flags = flags;
1788 #ifdef CONFIG_IP_ROUTE_CLASSID
1789 		if (nhc->nhc_family == AF_INET) {
1790 			struct fib_nh *nh;
1791 
1792 			nh = container_of(nhc, struct fib_nh, nh_common);
1793 			if (nh->nh_tclassid &&
1794 			    nla_put_u32(skb, RTA_FLOW, nh->nh_tclassid))
1795 				goto nla_put_failure;
1796 		}
1797 #endif
1798 	} else {
1799 		if (fib_add_multipath(skb, fi) < 0)
1800 			goto nla_put_failure;
1801 	}
1802 
1803 offload:
1804 	if (fri->offload)
1805 		rtm->rtm_flags |= RTM_F_OFFLOAD;
1806 	if (fri->trap)
1807 		rtm->rtm_flags |= RTM_F_TRAP;
1808 	if (fri->offload_failed)
1809 		rtm->rtm_flags |= RTM_F_OFFLOAD_FAILED;
1810 
1811 	nlmsg_end(skb, nlh);
1812 	return 0;
1813 
1814 nla_put_failure:
1815 	nlmsg_cancel(skb, nlh);
1816 	return -EMSGSIZE;
1817 }
1818 
1819 /*
1820  * Update FIB if:
1821  * - local address disappeared -> we must delete all the entries
1822  *   referring to it.
1823  * - device went down -> we must shutdown all nexthops going via it.
1824  */
fib_sync_down_addr(struct net_device * dev,__be32 local)1825 int fib_sync_down_addr(struct net_device *dev, __be32 local)
1826 {
1827 	int tb_id = l3mdev_fib_table(dev) ? : RT_TABLE_MAIN;
1828 	struct net *net = dev_net(dev);
1829 	struct hlist_head *head;
1830 	struct fib_info *fi;
1831 	int ret = 0;
1832 
1833 	if (!local)
1834 		return 0;
1835 
1836 	head = fib_info_laddrhash_bucket(net, local);
1837 	hlist_for_each_entry(fi, head, fib_lhash) {
1838 		if (!net_eq(fi->fib_net, net) ||
1839 		    fi->fib_tb_id != tb_id)
1840 			continue;
1841 		if (fi->fib_prefsrc == local) {
1842 			fi->fib_flags |= RTNH_F_DEAD;
1843 			fi->pfsrc_removed = true;
1844 			ret++;
1845 		}
1846 	}
1847 	return ret;
1848 }
1849 
call_fib_nh_notifiers(struct fib_nh * nh,enum fib_event_type event_type)1850 static int call_fib_nh_notifiers(struct fib_nh *nh,
1851 				 enum fib_event_type event_type)
1852 {
1853 	bool ignore_link_down = ip_ignore_linkdown(nh->fib_nh_dev);
1854 	struct fib_nh_notifier_info info = {
1855 		.fib_nh = nh,
1856 	};
1857 
1858 	switch (event_type) {
1859 	case FIB_EVENT_NH_ADD:
1860 		if (nh->fib_nh_flags & RTNH_F_DEAD)
1861 			break;
1862 		if (ignore_link_down && nh->fib_nh_flags & RTNH_F_LINKDOWN)
1863 			break;
1864 		return call_fib4_notifiers(dev_net(nh->fib_nh_dev), event_type,
1865 					   &info.info);
1866 	case FIB_EVENT_NH_DEL:
1867 		if ((ignore_link_down && nh->fib_nh_flags & RTNH_F_LINKDOWN) ||
1868 		    (nh->fib_nh_flags & RTNH_F_DEAD))
1869 			return call_fib4_notifiers(dev_net(nh->fib_nh_dev),
1870 						   event_type, &info.info);
1871 		break;
1872 	default:
1873 		break;
1874 	}
1875 
1876 	return NOTIFY_DONE;
1877 }
1878 
1879 /* Update the PMTU of exceptions when:
1880  * - the new MTU of the first hop becomes smaller than the PMTU
1881  * - the old MTU was the same as the PMTU, and it limited discovery of
1882  *   larger MTUs on the path. With that limit raised, we can now
1883  *   discover larger MTUs
1884  * A special case is locked exceptions, for which the PMTU is smaller
1885  * than the minimal accepted PMTU:
1886  * - if the new MTU is greater than the PMTU, don't make any change
1887  * - otherwise, unlock and set PMTU
1888  */
fib_nhc_update_mtu(struct fib_nh_common * nhc,u32 new,u32 orig)1889 void fib_nhc_update_mtu(struct fib_nh_common *nhc, u32 new, u32 orig)
1890 {
1891 	struct fnhe_hash_bucket *bucket;
1892 	int i;
1893 
1894 	bucket = rcu_dereference_protected(nhc->nhc_exceptions, 1);
1895 	if (!bucket)
1896 		return;
1897 
1898 	for (i = 0; i < FNHE_HASH_SIZE; i++) {
1899 		struct fib_nh_exception *fnhe;
1900 
1901 		for (fnhe = rcu_dereference_protected(bucket[i].chain, 1);
1902 		     fnhe;
1903 		     fnhe = rcu_dereference_protected(fnhe->fnhe_next, 1)) {
1904 			if (fnhe->fnhe_mtu_locked) {
1905 				if (new <= fnhe->fnhe_pmtu) {
1906 					fnhe->fnhe_pmtu = new;
1907 					fnhe->fnhe_mtu_locked = false;
1908 				}
1909 			} else if (new < fnhe->fnhe_pmtu ||
1910 				   orig == fnhe->fnhe_pmtu) {
1911 				fnhe->fnhe_pmtu = new;
1912 			}
1913 		}
1914 	}
1915 }
1916 
fib_sync_mtu(struct net_device * dev,u32 orig_mtu)1917 void fib_sync_mtu(struct net_device *dev, u32 orig_mtu)
1918 {
1919 	struct hlist_head *head = fib_nh_head(dev);
1920 	struct fib_nh *nh;
1921 
1922 	hlist_for_each_entry(nh, head, nh_hash) {
1923 		DEBUG_NET_WARN_ON_ONCE(nh->fib_nh_dev != dev);
1924 		fib_nhc_update_mtu(&nh->nh_common, dev->mtu, orig_mtu);
1925 	}
1926 }
1927 
1928 /* Event              force Flags           Description
1929  * NETDEV_CHANGE      0     LINKDOWN        Carrier OFF, not for scope host
1930  * NETDEV_DOWN        0     LINKDOWN|DEAD   Link down, not for scope host
1931  * NETDEV_DOWN        1     LINKDOWN|DEAD   Last address removed
1932  * NETDEV_UNREGISTER  1     LINKDOWN|DEAD   Device removed
1933  *
1934  * only used when fib_nh is built into fib_info
1935  */
fib_sync_down_dev(struct net_device * dev,unsigned long event,bool force)1936 int fib_sync_down_dev(struct net_device *dev, unsigned long event, bool force)
1937 {
1938 	struct hlist_head *head = fib_nh_head(dev);
1939 	struct fib_info *prev_fi = NULL;
1940 	int scope = RT_SCOPE_NOWHERE;
1941 	struct fib_nh *nh;
1942 	int ret = 0;
1943 
1944 	if (force)
1945 		scope = -1;
1946 
1947 	hlist_for_each_entry(nh, head, nh_hash) {
1948 		struct fib_info *fi = nh->nh_parent;
1949 		int dead;
1950 
1951 		BUG_ON(!fi->fib_nhs);
1952 		DEBUG_NET_WARN_ON_ONCE(nh->fib_nh_dev != dev);
1953 		if (fi == prev_fi)
1954 			continue;
1955 		prev_fi = fi;
1956 		dead = 0;
1957 		change_nexthops(fi) {
1958 			if (nexthop_nh->fib_nh_flags & RTNH_F_DEAD)
1959 				dead++;
1960 			else if (nexthop_nh->fib_nh_dev == dev &&
1961 				 nexthop_nh->fib_nh_scope != scope) {
1962 				switch (event) {
1963 				case NETDEV_DOWN:
1964 				case NETDEV_UNREGISTER:
1965 					nexthop_nh->fib_nh_flags |= RTNH_F_DEAD;
1966 					fallthrough;
1967 				case NETDEV_CHANGE:
1968 					nexthop_nh->fib_nh_flags |= RTNH_F_LINKDOWN;
1969 					break;
1970 				}
1971 				call_fib_nh_notifiers(nexthop_nh,
1972 						      FIB_EVENT_NH_DEL);
1973 				dead++;
1974 			}
1975 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1976 			if (event == NETDEV_UNREGISTER &&
1977 			    nexthop_nh->fib_nh_dev == dev) {
1978 				dead = fi->fib_nhs;
1979 				break;
1980 			}
1981 #endif
1982 		} endfor_nexthops(fi)
1983 		if (dead == fi->fib_nhs) {
1984 			switch (event) {
1985 			case NETDEV_DOWN:
1986 			case NETDEV_UNREGISTER:
1987 				fi->fib_flags |= RTNH_F_DEAD;
1988 				fallthrough;
1989 			case NETDEV_CHANGE:
1990 				fi->fib_flags |= RTNH_F_LINKDOWN;
1991 				break;
1992 			}
1993 			ret++;
1994 		}
1995 
1996 		fib_rebalance(fi);
1997 	}
1998 
1999 	return ret;
2000 }
2001 
2002 /* Must be invoked inside of an RCU protected region.  */
fib_select_default(const struct flowi4 * flp,struct fib_result * res)2003 static void fib_select_default(const struct flowi4 *flp, struct fib_result *res)
2004 {
2005 	struct fib_info *fi = NULL, *last_resort = NULL;
2006 	struct hlist_head *fa_head = res->fa_head;
2007 	struct fib_table *tb = res->table;
2008 	u8 slen = 32 - res->prefixlen;
2009 	int order = -1, last_idx = -1;
2010 	struct fib_alias *fa, *fa1 = NULL;
2011 	u32 last_prio = res->fi->fib_priority;
2012 	dscp_t last_dscp = 0;
2013 
2014 	hlist_for_each_entry_rcu(fa, fa_head, fa_list) {
2015 		struct fib_info *next_fi = fa->fa_info;
2016 		struct fib_nh_common *nhc;
2017 
2018 		if (fa->fa_slen != slen)
2019 			continue;
2020 		if (fa->fa_dscp && !fib_dscp_masked_match(fa->fa_dscp, flp))
2021 			continue;
2022 		if (fa->tb_id != tb->tb_id)
2023 			continue;
2024 		if (next_fi->fib_priority > last_prio &&
2025 		    fa->fa_dscp == last_dscp) {
2026 			if (last_dscp)
2027 				continue;
2028 			break;
2029 		}
2030 		if (next_fi->fib_flags & RTNH_F_DEAD)
2031 			continue;
2032 		last_dscp = fa->fa_dscp;
2033 		last_prio = next_fi->fib_priority;
2034 
2035 		if (next_fi->fib_scope != res->scope ||
2036 		    fa->fa_type != RTN_UNICAST)
2037 			continue;
2038 
2039 		nhc = fib_info_nhc(next_fi, 0);
2040 		if (!nhc->nhc_gw_family || nhc->nhc_scope != RT_SCOPE_LINK)
2041 			continue;
2042 
2043 		fib_alias_accessed(fa);
2044 
2045 		if (!fi) {
2046 			if (next_fi != res->fi)
2047 				break;
2048 			fa1 = fa;
2049 		} else if (!fib_detect_death(fi, order, &last_resort,
2050 					     &last_idx, fa1->fa_default)) {
2051 			fib_result_assign(res, fi);
2052 			fa1->fa_default = order;
2053 			goto out;
2054 		}
2055 		fi = next_fi;
2056 		order++;
2057 	}
2058 
2059 	if (order <= 0 || !fi) {
2060 		if (fa1)
2061 			fa1->fa_default = -1;
2062 		goto out;
2063 	}
2064 
2065 	if (!fib_detect_death(fi, order, &last_resort, &last_idx,
2066 			      fa1->fa_default)) {
2067 		fib_result_assign(res, fi);
2068 		fa1->fa_default = order;
2069 		goto out;
2070 	}
2071 
2072 	if (last_idx >= 0)
2073 		fib_result_assign(res, last_resort);
2074 	fa1->fa_default = last_idx;
2075 out:
2076 	return;
2077 }
2078 
2079 /*
2080  * Dead device goes up. We wake up dead nexthops.
2081  * It takes sense only on multipath routes.
2082  *
2083  * only used when fib_nh is built into fib_info
2084  */
fib_sync_up(struct net_device * dev,unsigned char nh_flags)2085 int fib_sync_up(struct net_device *dev, unsigned char nh_flags)
2086 {
2087 	struct fib_info *prev_fi;
2088 	struct hlist_head *head;
2089 	struct fib_nh *nh;
2090 	int ret;
2091 
2092 	if (!(dev->flags & IFF_UP))
2093 		return 0;
2094 
2095 	if (nh_flags & RTNH_F_DEAD) {
2096 		unsigned int flags = dev_get_flags(dev);
2097 
2098 		if (flags & (IFF_RUNNING | IFF_LOWER_UP))
2099 			nh_flags |= RTNH_F_LINKDOWN;
2100 	}
2101 
2102 	prev_fi = NULL;
2103 	head = fib_nh_head(dev);
2104 	ret = 0;
2105 
2106 	hlist_for_each_entry(nh, head, nh_hash) {
2107 		struct fib_info *fi = nh->nh_parent;
2108 		int alive;
2109 
2110 		BUG_ON(!fi->fib_nhs);
2111 		DEBUG_NET_WARN_ON_ONCE(nh->fib_nh_dev != dev);
2112 		if (fi == prev_fi)
2113 			continue;
2114 
2115 		prev_fi = fi;
2116 		alive = 0;
2117 		change_nexthops(fi) {
2118 			if (!(nexthop_nh->fib_nh_flags & nh_flags)) {
2119 				alive++;
2120 				continue;
2121 			}
2122 			if (!nexthop_nh->fib_nh_dev ||
2123 			    !(nexthop_nh->fib_nh_dev->flags & IFF_UP))
2124 				continue;
2125 			if (nexthop_nh->fib_nh_dev != dev ||
2126 			    !__in_dev_get_rtnl(dev))
2127 				continue;
2128 			alive++;
2129 			nexthop_nh->fib_nh_flags &= ~nh_flags;
2130 			call_fib_nh_notifiers(nexthop_nh, FIB_EVENT_NH_ADD);
2131 		} endfor_nexthops(fi)
2132 
2133 		if (alive > 0) {
2134 			fi->fib_flags &= ~nh_flags;
2135 			ret++;
2136 		}
2137 
2138 		fib_rebalance(fi);
2139 	}
2140 
2141 	return ret;
2142 }
2143 
2144 #ifdef CONFIG_IP_ROUTE_MULTIPATH
fib_good_nh(const struct fib_nh * nh)2145 static bool fib_good_nh(const struct fib_nh *nh)
2146 {
2147 	int state = NUD_REACHABLE;
2148 
2149 	if (nh->fib_nh_scope == RT_SCOPE_LINK) {
2150 		struct neighbour *n;
2151 
2152 		rcu_read_lock();
2153 
2154 		if (likely(nh->fib_nh_gw_family == AF_INET))
2155 			n = __ipv4_neigh_lookup_noref(nh->fib_nh_dev,
2156 						   (__force u32)nh->fib_nh_gw4);
2157 		else if (nh->fib_nh_gw_family == AF_INET6)
2158 			n = __ipv6_neigh_lookup_noref_stub(nh->fib_nh_dev,
2159 							   &nh->fib_nh_gw6);
2160 		else
2161 			n = NULL;
2162 		if (n)
2163 			state = READ_ONCE(n->nud_state);
2164 
2165 		rcu_read_unlock();
2166 	}
2167 
2168 	return !!(state & NUD_VALID);
2169 }
2170 
fib_select_multipath(struct fib_result * res,int hash)2171 void fib_select_multipath(struct fib_result *res, int hash)
2172 {
2173 	struct fib_info *fi = res->fi;
2174 	struct net *net = fi->fib_net;
2175 	bool first = false;
2176 
2177 	if (unlikely(res->fi->nh)) {
2178 		nexthop_path_fib_result(res, hash);
2179 		return;
2180 	}
2181 
2182 	change_nexthops(fi) {
2183 		if (READ_ONCE(net->ipv4.sysctl_fib_multipath_use_neigh)) {
2184 			if (!fib_good_nh(nexthop_nh))
2185 				continue;
2186 			if (!first) {
2187 				res->nh_sel = nhsel;
2188 				res->nhc = &nexthop_nh->nh_common;
2189 				first = true;
2190 			}
2191 		}
2192 
2193 		if (hash > atomic_read(&nexthop_nh->fib_nh_upper_bound))
2194 			continue;
2195 
2196 		res->nh_sel = nhsel;
2197 		res->nhc = &nexthop_nh->nh_common;
2198 		return;
2199 	} endfor_nexthops(fi);
2200 }
2201 #endif
2202 
fib_select_path(struct net * net,struct fib_result * res,struct flowi4 * fl4,const struct sk_buff * skb)2203 void fib_select_path(struct net *net, struct fib_result *res,
2204 		     struct flowi4 *fl4, const struct sk_buff *skb)
2205 {
2206 	if (fl4->flowi4_oif)
2207 		goto check_saddr;
2208 
2209 #ifdef CONFIG_IP_ROUTE_MULTIPATH
2210 	if (fib_info_num_path(res->fi) > 1) {
2211 		int h = fib_multipath_hash(net, fl4, skb, NULL);
2212 
2213 		fib_select_multipath(res, h);
2214 	}
2215 	else
2216 #endif
2217 	if (!res->prefixlen &&
2218 	    res->table->tb_num_default > 1 &&
2219 	    res->type == RTN_UNICAST)
2220 		fib_select_default(fl4, res);
2221 
2222 check_saddr:
2223 	if (!fl4->saddr) {
2224 		struct net_device *l3mdev;
2225 
2226 		l3mdev = dev_get_by_index_rcu(net, fl4->flowi4_l3mdev);
2227 
2228 		if (!l3mdev ||
2229 		    l3mdev_master_dev_rcu(FIB_RES_DEV(*res)) == l3mdev)
2230 			fl4->saddr = fib_result_prefsrc(net, res);
2231 		else
2232 			fl4->saddr = inet_select_addr(l3mdev, 0, RT_SCOPE_LINK);
2233 	}
2234 }
2235 
fib4_semantics_init(struct net * net)2236 int __net_init fib4_semantics_init(struct net *net)
2237 {
2238 	unsigned int hash_bits = 4;
2239 
2240 	net->ipv4.fib_info_hash = fib_info_hash_alloc(hash_bits);
2241 	if (!net->ipv4.fib_info_hash)
2242 		return -ENOMEM;
2243 
2244 	net->ipv4.fib_info_hash_bits = hash_bits;
2245 	net->ipv4.fib_info_cnt = 0;
2246 
2247 	return 0;
2248 }
2249 
fib4_semantics_exit(struct net * net)2250 void __net_exit fib4_semantics_exit(struct net *net)
2251 {
2252 	fib_info_hash_free(net->ipv4.fib_info_hash);
2253 }
2254