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 static DEFINE_SPINLOCK(fib_info_lock);
54 static struct hlist_head *fib_info_hash;
55 static struct hlist_head *fib_info_laddrhash;
56 static unsigned int fib_info_hash_size;
57 static unsigned int fib_info_hash_bits;
58 static unsigned int fib_info_cnt;
59 
60 #define DEVINDEX_HASHBITS 8
61 #define DEVINDEX_HASHSIZE (1U << DEVINDEX_HASHBITS)
62 static struct hlist_head fib_info_devhash[DEVINDEX_HASHSIZE];
63 
64 /* for_nexthops and change_nexthops only used when nexthop object
65  * is not set in a fib_info. The logic within can reference fib_nh.
66  */
67 #ifdef CONFIG_IP_ROUTE_MULTIPATH
68 
69 #define for_nexthops(fi) {						\
70 	int nhsel; const struct fib_nh *nh;				\
71 	for (nhsel = 0, nh = (fi)->fib_nh;				\
72 	     nhsel < fib_info_num_path((fi));				\
73 	     nh++, nhsel++)
74 
75 #define change_nexthops(fi) {						\
76 	int nhsel; struct fib_nh *nexthop_nh;				\
77 	for (nhsel = 0,	nexthop_nh = (struct fib_nh *)((fi)->fib_nh);	\
78 	     nhsel < fib_info_num_path((fi));				\
79 	     nexthop_nh++, nhsel++)
80 
81 #else /* CONFIG_IP_ROUTE_MULTIPATH */
82 
83 /* Hope, that gcc will optimize it to get rid of dummy loop */
84 
85 #define for_nexthops(fi) {						\
86 	int nhsel; const struct fib_nh *nh = (fi)->fib_nh;		\
87 	for (nhsel = 0; nhsel < 1; nhsel++)
88 
89 #define change_nexthops(fi) {						\
90 	int nhsel;							\
91 	struct fib_nh *nexthop_nh = (struct fib_nh *)((fi)->fib_nh);	\
92 	for (nhsel = 0; nhsel < 1; nhsel++)
93 
94 #endif /* CONFIG_IP_ROUTE_MULTIPATH */
95 
96 #define endfor_nexthops(fi) }
97 
98 
99 const struct fib_prop fib_props[RTN_MAX + 1] = {
100 	[RTN_UNSPEC] = {
101 		.error	= 0,
102 		.scope	= RT_SCOPE_NOWHERE,
103 	},
104 	[RTN_UNICAST] = {
105 		.error	= 0,
106 		.scope	= RT_SCOPE_UNIVERSE,
107 	},
108 	[RTN_LOCAL] = {
109 		.error	= 0,
110 		.scope	= RT_SCOPE_HOST,
111 	},
112 	[RTN_BROADCAST] = {
113 		.error	= 0,
114 		.scope	= RT_SCOPE_LINK,
115 	},
116 	[RTN_ANYCAST] = {
117 		.error	= 0,
118 		.scope	= RT_SCOPE_LINK,
119 	},
120 	[RTN_MULTICAST] = {
121 		.error	= 0,
122 		.scope	= RT_SCOPE_UNIVERSE,
123 	},
124 	[RTN_BLACKHOLE] = {
125 		.error	= -EINVAL,
126 		.scope	= RT_SCOPE_UNIVERSE,
127 	},
128 	[RTN_UNREACHABLE] = {
129 		.error	= -EHOSTUNREACH,
130 		.scope	= RT_SCOPE_UNIVERSE,
131 	},
132 	[RTN_PROHIBIT] = {
133 		.error	= -EACCES,
134 		.scope	= RT_SCOPE_UNIVERSE,
135 	},
136 	[RTN_THROW] = {
137 		.error	= -EAGAIN,
138 		.scope	= RT_SCOPE_UNIVERSE,
139 	},
140 	[RTN_NAT] = {
141 		.error	= -EINVAL,
142 		.scope	= RT_SCOPE_NOWHERE,
143 	},
144 	[RTN_XRESOLVE] = {
145 		.error	= -EINVAL,
146 		.scope	= RT_SCOPE_NOWHERE,
147 	},
148 };
149 
rt_fibinfo_free(struct rtable __rcu ** rtp)150 static void rt_fibinfo_free(struct rtable __rcu **rtp)
151 {
152 	struct rtable *rt = rcu_dereference_protected(*rtp, 1);
153 
154 	if (!rt)
155 		return;
156 
157 	/* Not even needed : RCU_INIT_POINTER(*rtp, NULL);
158 	 * because we waited an RCU grace period before calling
159 	 * free_fib_info_rcu()
160 	 */
161 
162 	dst_dev_put(&rt->dst);
163 	dst_release_immediate(&rt->dst);
164 }
165 
free_nh_exceptions(struct fib_nh_common * nhc)166 static void free_nh_exceptions(struct fib_nh_common *nhc)
167 {
168 	struct fnhe_hash_bucket *hash;
169 	int i;
170 
171 	hash = rcu_dereference_protected(nhc->nhc_exceptions, 1);
172 	if (!hash)
173 		return;
174 	for (i = 0; i < FNHE_HASH_SIZE; i++) {
175 		struct fib_nh_exception *fnhe;
176 
177 		fnhe = rcu_dereference_protected(hash[i].chain, 1);
178 		while (fnhe) {
179 			struct fib_nh_exception *next;
180 
181 			next = rcu_dereference_protected(fnhe->fnhe_next, 1);
182 
183 			rt_fibinfo_free(&fnhe->fnhe_rth_input);
184 			rt_fibinfo_free(&fnhe->fnhe_rth_output);
185 
186 			kfree(fnhe);
187 
188 			fnhe = next;
189 		}
190 	}
191 	kfree(hash);
192 }
193 
rt_fibinfo_free_cpus(struct rtable __rcu * __percpu * rtp)194 static void rt_fibinfo_free_cpus(struct rtable __rcu * __percpu *rtp)
195 {
196 	int cpu;
197 
198 	if (!rtp)
199 		return;
200 
201 	for_each_possible_cpu(cpu) {
202 		struct rtable *rt;
203 
204 		rt = rcu_dereference_protected(*per_cpu_ptr(rtp, cpu), 1);
205 		if (rt) {
206 			dst_dev_put(&rt->dst);
207 			dst_release_immediate(&rt->dst);
208 		}
209 	}
210 	free_percpu(rtp);
211 }
212 
fib_nh_common_release(struct fib_nh_common * nhc)213 void fib_nh_common_release(struct fib_nh_common *nhc)
214 {
215 	netdev_put(nhc->nhc_dev, &nhc->nhc_dev_tracker);
216 	lwtstate_put(nhc->nhc_lwtstate);
217 	rt_fibinfo_free_cpus(nhc->nhc_pcpu_rth_output);
218 	rt_fibinfo_free(&nhc->nhc_rth_input);
219 	free_nh_exceptions(nhc);
220 }
221 EXPORT_SYMBOL_GPL(fib_nh_common_release);
222 
fib_nh_release(struct net * net,struct fib_nh * fib_nh)223 void fib_nh_release(struct net *net, struct fib_nh *fib_nh)
224 {
225 #ifdef CONFIG_IP_ROUTE_CLASSID
226 	if (fib_nh->nh_tclassid)
227 		atomic_dec(&net->ipv4.fib_num_tclassid_users);
228 #endif
229 	fib_nh_common_release(&fib_nh->nh_common);
230 }
231 
232 /* Release a nexthop info record */
free_fib_info_rcu(struct rcu_head * head)233 static void free_fib_info_rcu(struct rcu_head *head)
234 {
235 	struct fib_info *fi = container_of(head, struct fib_info, rcu);
236 
237 	if (fi->nh) {
238 		nexthop_put(fi->nh);
239 	} else {
240 		change_nexthops(fi) {
241 			fib_nh_release(fi->fib_net, nexthop_nh);
242 		} endfor_nexthops(fi);
243 	}
244 
245 	ip_fib_metrics_put(fi->fib_metrics);
246 
247 	kfree(fi);
248 }
249 
free_fib_info(struct fib_info * fi)250 void free_fib_info(struct fib_info *fi)
251 {
252 	if (fi->fib_dead == 0) {
253 		pr_warn("Freeing alive fib_info %p\n", fi);
254 		return;
255 	}
256 
257 	call_rcu(&fi->rcu, free_fib_info_rcu);
258 }
259 EXPORT_SYMBOL_GPL(free_fib_info);
260 
fib_release_info(struct fib_info * fi)261 void fib_release_info(struct fib_info *fi)
262 {
263 	spin_lock_bh(&fib_info_lock);
264 	if (fi && refcount_dec_and_test(&fi->fib_treeref)) {
265 		hlist_del(&fi->fib_hash);
266 
267 		/* Paired with READ_ONCE() in fib_create_info(). */
268 		WRITE_ONCE(fib_info_cnt, fib_info_cnt - 1);
269 
270 		if (fi->fib_prefsrc)
271 			hlist_del(&fi->fib_lhash);
272 		if (fi->nh) {
273 			list_del(&fi->nh_list);
274 		} else {
275 			change_nexthops(fi) {
276 				if (!nexthop_nh->fib_nh_dev)
277 					continue;
278 				hlist_del(&nexthop_nh->nh_hash);
279 			} endfor_nexthops(fi)
280 		}
281 		/* Paired with READ_ONCE() from fib_table_lookup() */
282 		WRITE_ONCE(fi->fib_dead, 1);
283 		fib_info_put(fi);
284 	}
285 	spin_unlock_bh(&fib_info_lock);
286 }
287 
nh_comp(struct fib_info * fi,struct fib_info * ofi)288 static inline int nh_comp(struct fib_info *fi, struct fib_info *ofi)
289 {
290 	const struct fib_nh *onh;
291 
292 	if (fi->nh || ofi->nh)
293 		return nexthop_cmp(fi->nh, ofi->nh) ? 0 : -1;
294 
295 	if (ofi->fib_nhs == 0)
296 		return 0;
297 
298 	for_nexthops(fi) {
299 		onh = fib_info_nh(ofi, nhsel);
300 
301 		if (nh->fib_nh_oif != onh->fib_nh_oif ||
302 		    nh->fib_nh_gw_family != onh->fib_nh_gw_family ||
303 		    nh->fib_nh_scope != onh->fib_nh_scope ||
304 #ifdef CONFIG_IP_ROUTE_MULTIPATH
305 		    nh->fib_nh_weight != onh->fib_nh_weight ||
306 #endif
307 #ifdef CONFIG_IP_ROUTE_CLASSID
308 		    nh->nh_tclassid != onh->nh_tclassid ||
309 #endif
310 		    lwtunnel_cmp_encap(nh->fib_nh_lws, onh->fib_nh_lws) ||
311 		    ((nh->fib_nh_flags ^ onh->fib_nh_flags) & ~RTNH_COMPARE_MASK))
312 			return -1;
313 
314 		if (nh->fib_nh_gw_family == AF_INET &&
315 		    nh->fib_nh_gw4 != onh->fib_nh_gw4)
316 			return -1;
317 
318 		if (nh->fib_nh_gw_family == AF_INET6 &&
319 		    ipv6_addr_cmp(&nh->fib_nh_gw6, &onh->fib_nh_gw6))
320 			return -1;
321 	} endfor_nexthops(fi);
322 	return 0;
323 }
324 
fib_devindex_hashfn(unsigned int val)325 static inline unsigned int fib_devindex_hashfn(unsigned int val)
326 {
327 	return hash_32(val, DEVINDEX_HASHBITS);
328 }
329 
330 static struct hlist_head *
fib_info_devhash_bucket(const struct net_device * dev)331 fib_info_devhash_bucket(const struct net_device *dev)
332 {
333 	u32 val = net_hash_mix(dev_net(dev)) ^ dev->ifindex;
334 
335 	return &fib_info_devhash[fib_devindex_hashfn(val)];
336 }
337 
fib_info_hashfn_1(int init_val,u8 protocol,u8 scope,u32 prefsrc,u32 priority)338 static unsigned int fib_info_hashfn_1(int init_val, u8 protocol, u8 scope,
339 				      u32 prefsrc, u32 priority)
340 {
341 	unsigned int val = init_val;
342 
343 	val ^= (protocol << 8) | scope;
344 	val ^= prefsrc;
345 	val ^= priority;
346 
347 	return val;
348 }
349 
fib_info_hashfn_result(unsigned int val)350 static unsigned int fib_info_hashfn_result(unsigned int val)
351 {
352 	unsigned int mask = (fib_info_hash_size - 1);
353 
354 	return (val ^ (val >> 7) ^ (val >> 12)) & mask;
355 }
356 
fib_info_hashfn(struct fib_info * fi)357 static inline unsigned int fib_info_hashfn(struct fib_info *fi)
358 {
359 	unsigned int val;
360 
361 	val = fib_info_hashfn_1(fi->fib_nhs, fi->fib_protocol,
362 				fi->fib_scope, (__force u32)fi->fib_prefsrc,
363 				fi->fib_priority);
364 
365 	if (fi->nh) {
366 		val ^= fib_devindex_hashfn(fi->nh->id);
367 	} else {
368 		for_nexthops(fi) {
369 			val ^= fib_devindex_hashfn(nh->fib_nh_oif);
370 		} endfor_nexthops(fi)
371 	}
372 
373 	return fib_info_hashfn_result(val);
374 }
375 
376 /* no metrics, only nexthop id */
fib_find_info_nh(struct net * net,const struct fib_config * cfg)377 static struct fib_info *fib_find_info_nh(struct net *net,
378 					 const struct fib_config *cfg)
379 {
380 	struct hlist_head *head;
381 	struct fib_info *fi;
382 	unsigned int hash;
383 
384 	hash = fib_info_hashfn_1(fib_devindex_hashfn(cfg->fc_nh_id),
385 				 cfg->fc_protocol, cfg->fc_scope,
386 				 (__force u32)cfg->fc_prefsrc,
387 				 cfg->fc_priority);
388 	hash = fib_info_hashfn_result(hash);
389 	head = &fib_info_hash[hash];
390 
391 	hlist_for_each_entry(fi, head, fib_hash) {
392 		if (!net_eq(fi->fib_net, net))
393 			continue;
394 		if (!fi->nh || fi->nh->id != cfg->fc_nh_id)
395 			continue;
396 		if (cfg->fc_protocol == fi->fib_protocol &&
397 		    cfg->fc_scope == fi->fib_scope &&
398 		    cfg->fc_prefsrc == fi->fib_prefsrc &&
399 		    cfg->fc_priority == fi->fib_priority &&
400 		    cfg->fc_type == fi->fib_type &&
401 		    cfg->fc_table == fi->fib_tb_id &&
402 		    !((cfg->fc_flags ^ fi->fib_flags) & ~RTNH_COMPARE_MASK))
403 			return fi;
404 	}
405 
406 	return NULL;
407 }
408 
fib_find_info(struct fib_info * nfi)409 static struct fib_info *fib_find_info(struct fib_info *nfi)
410 {
411 	struct hlist_head *head;
412 	struct fib_info *fi;
413 	unsigned int hash;
414 
415 	hash = fib_info_hashfn(nfi);
416 	head = &fib_info_hash[hash];
417 
418 	hlist_for_each_entry(fi, head, fib_hash) {
419 		if (!net_eq(fi->fib_net, nfi->fib_net))
420 			continue;
421 		if (fi->fib_nhs != nfi->fib_nhs)
422 			continue;
423 		if (nfi->fib_protocol == fi->fib_protocol &&
424 		    nfi->fib_scope == fi->fib_scope &&
425 		    nfi->fib_prefsrc == fi->fib_prefsrc &&
426 		    nfi->fib_priority == fi->fib_priority &&
427 		    nfi->fib_type == fi->fib_type &&
428 		    nfi->fib_tb_id == fi->fib_tb_id &&
429 		    memcmp(nfi->fib_metrics, fi->fib_metrics,
430 			   sizeof(u32) * RTAX_MAX) == 0 &&
431 		    !((nfi->fib_flags ^ fi->fib_flags) & ~RTNH_COMPARE_MASK) &&
432 		    nh_comp(fi, nfi) == 0)
433 			return fi;
434 	}
435 
436 	return NULL;
437 }
438 
439 /* Check, that the gateway is already configured.
440  * Used only by redirect accept routine.
441  */
ip_fib_check_default(__be32 gw,struct net_device * dev)442 int ip_fib_check_default(__be32 gw, struct net_device *dev)
443 {
444 	struct hlist_head *head;
445 	struct fib_nh *nh;
446 
447 	spin_lock(&fib_info_lock);
448 
449 	head = fib_info_devhash_bucket(dev);
450 
451 	hlist_for_each_entry(nh, head, nh_hash) {
452 		if (nh->fib_nh_dev == dev &&
453 		    nh->fib_nh_gw4 == gw &&
454 		    !(nh->fib_nh_flags & RTNH_F_DEAD)) {
455 			spin_unlock(&fib_info_lock);
456 			return 0;
457 		}
458 	}
459 
460 	spin_unlock(&fib_info_lock);
461 
462 	return -1;
463 }
464 
fib_nlmsg_size(struct fib_info * fi)465 size_t fib_nlmsg_size(struct fib_info *fi)
466 {
467 	size_t payload = NLMSG_ALIGN(sizeof(struct rtmsg))
468 			 + nla_total_size(4) /* RTA_TABLE */
469 			 + nla_total_size(4) /* RTA_DST */
470 			 + nla_total_size(4) /* RTA_PRIORITY */
471 			 + nla_total_size(4) /* RTA_PREFSRC */
472 			 + nla_total_size(TCP_CA_NAME_MAX); /* RTAX_CC_ALGO */
473 	unsigned int nhs = fib_info_num_path(fi);
474 
475 	/* space for nested metrics */
476 	payload += nla_total_size((RTAX_MAX * nla_total_size(4)));
477 
478 	if (fi->nh)
479 		payload += nla_total_size(4); /* RTA_NH_ID */
480 
481 	if (nhs) {
482 		size_t nh_encapsize = 0;
483 		/* Also handles the special case nhs == 1 */
484 
485 		/* each nexthop is packed in an attribute */
486 		size_t nhsize = nla_total_size(sizeof(struct rtnexthop));
487 		unsigned int i;
488 
489 		/* may contain flow and gateway attribute */
490 		nhsize += 2 * nla_total_size(4);
491 
492 		/* grab encap info */
493 		for (i = 0; i < fib_info_num_path(fi); i++) {
494 			struct fib_nh_common *nhc = fib_info_nhc(fi, i);
495 
496 			if (nhc->nhc_lwtstate) {
497 				/* RTA_ENCAP_TYPE */
498 				nh_encapsize += lwtunnel_get_encap_size(
499 						nhc->nhc_lwtstate);
500 				/* RTA_ENCAP */
501 				nh_encapsize +=  nla_total_size(2);
502 			}
503 		}
504 
505 		/* all nexthops are packed in a nested attribute */
506 		payload += nla_total_size((nhs * nhsize) + nh_encapsize);
507 
508 	}
509 
510 	return payload;
511 }
512 
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)513 void rtmsg_fib(int event, __be32 key, struct fib_alias *fa,
514 	       int dst_len, u32 tb_id, const struct nl_info *info,
515 	       unsigned int nlm_flags)
516 {
517 	struct fib_rt_info fri;
518 	struct sk_buff *skb;
519 	u32 seq = info->nlh ? info->nlh->nlmsg_seq : 0;
520 	int err = -ENOBUFS;
521 
522 	skb = nlmsg_new(fib_nlmsg_size(fa->fa_info), GFP_KERNEL);
523 	if (!skb)
524 		goto errout;
525 
526 	fri.fi = fa->fa_info;
527 	fri.tb_id = tb_id;
528 	fri.dst = key;
529 	fri.dst_len = dst_len;
530 	fri.dscp = fa->fa_dscp;
531 	fri.type = fa->fa_type;
532 	fri.offload = READ_ONCE(fa->offload);
533 	fri.trap = READ_ONCE(fa->trap);
534 	fri.offload_failed = READ_ONCE(fa->offload_failed);
535 	err = fib_dump_info(skb, info->portid, seq, event, &fri, nlm_flags);
536 	if (err < 0) {
537 		/* -EMSGSIZE implies BUG in fib_nlmsg_size() */
538 		WARN_ON(err == -EMSGSIZE);
539 		kfree_skb(skb);
540 		goto errout;
541 	}
542 	rtnl_notify(skb, info->nl_net, info->portid, RTNLGRP_IPV4_ROUTE,
543 		    info->nlh, GFP_KERNEL);
544 	return;
545 errout:
546 	if (err < 0)
547 		rtnl_set_sk_err(info->nl_net, RTNLGRP_IPV4_ROUTE, err);
548 }
549 
fib_detect_death(struct fib_info * fi,int order,struct fib_info ** last_resort,int * last_idx,int dflt)550 static int fib_detect_death(struct fib_info *fi, int order,
551 			    struct fib_info **last_resort, int *last_idx,
552 			    int dflt)
553 {
554 	const struct fib_nh_common *nhc = fib_info_nhc(fi, 0);
555 	struct neighbour *n;
556 	int state = NUD_NONE;
557 
558 	if (likely(nhc->nhc_gw_family == AF_INET))
559 		n = neigh_lookup(&arp_tbl, &nhc->nhc_gw.ipv4, nhc->nhc_dev);
560 	else if (nhc->nhc_gw_family == AF_INET6)
561 		n = neigh_lookup(ipv6_stub->nd_tbl, &nhc->nhc_gw.ipv6,
562 				 nhc->nhc_dev);
563 	else
564 		n = NULL;
565 
566 	if (n) {
567 		state = READ_ONCE(n->nud_state);
568 		neigh_release(n);
569 	} else {
570 		return 0;
571 	}
572 	if (state == NUD_REACHABLE)
573 		return 0;
574 	if ((state & NUD_VALID) && order != dflt)
575 		return 0;
576 	if ((state & NUD_VALID) ||
577 	    (*last_idx < 0 && order > dflt && state != NUD_INCOMPLETE)) {
578 		*last_resort = fi;
579 		*last_idx = order;
580 	}
581 	return 1;
582 }
583 
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)584 int fib_nh_common_init(struct net *net, struct fib_nh_common *nhc,
585 		       struct nlattr *encap, u16 encap_type,
586 		       void *cfg, gfp_t gfp_flags,
587 		       struct netlink_ext_ack *extack)
588 {
589 	int err;
590 
591 	nhc->nhc_pcpu_rth_output = alloc_percpu_gfp(struct rtable __rcu *,
592 						    gfp_flags);
593 	if (!nhc->nhc_pcpu_rth_output)
594 		return -ENOMEM;
595 
596 	if (encap) {
597 		struct lwtunnel_state *lwtstate;
598 
599 		if (encap_type == LWTUNNEL_ENCAP_NONE) {
600 			NL_SET_ERR_MSG(extack, "LWT encap type not specified");
601 			err = -EINVAL;
602 			goto lwt_failure;
603 		}
604 		err = lwtunnel_build_state(net, encap_type, encap,
605 					   nhc->nhc_family, cfg, &lwtstate,
606 					   extack);
607 		if (err)
608 			goto lwt_failure;
609 
610 		nhc->nhc_lwtstate = lwtstate_get(lwtstate);
611 	}
612 
613 	return 0;
614 
615 lwt_failure:
616 	rt_fibinfo_free_cpus(nhc->nhc_pcpu_rth_output);
617 	nhc->nhc_pcpu_rth_output = NULL;
618 	return err;
619 }
620 EXPORT_SYMBOL_GPL(fib_nh_common_init);
621 
fib_nh_init(struct net * net,struct fib_nh * nh,struct fib_config * cfg,int nh_weight,struct netlink_ext_ack * extack)622 int fib_nh_init(struct net *net, struct fib_nh *nh,
623 		struct fib_config *cfg, int nh_weight,
624 		struct netlink_ext_ack *extack)
625 {
626 	int err;
627 
628 	nh->fib_nh_family = AF_INET;
629 
630 	err = fib_nh_common_init(net, &nh->nh_common, cfg->fc_encap,
631 				 cfg->fc_encap_type, cfg, GFP_KERNEL, extack);
632 	if (err)
633 		return err;
634 
635 	nh->fib_nh_oif = cfg->fc_oif;
636 	nh->fib_nh_gw_family = cfg->fc_gw_family;
637 	if (cfg->fc_gw_family == AF_INET)
638 		nh->fib_nh_gw4 = cfg->fc_gw4;
639 	else if (cfg->fc_gw_family == AF_INET6)
640 		nh->fib_nh_gw6 = cfg->fc_gw6;
641 
642 	nh->fib_nh_flags = cfg->fc_flags;
643 
644 #ifdef CONFIG_IP_ROUTE_CLASSID
645 	nh->nh_tclassid = cfg->fc_flow;
646 	if (nh->nh_tclassid)
647 		atomic_inc(&net->ipv4.fib_num_tclassid_users);
648 #endif
649 #ifdef CONFIG_IP_ROUTE_MULTIPATH
650 	nh->fib_nh_weight = nh_weight;
651 #endif
652 	return 0;
653 }
654 
655 #ifdef CONFIG_IP_ROUTE_MULTIPATH
656 
fib_count_nexthops(struct rtnexthop * rtnh,int remaining,struct netlink_ext_ack * extack)657 static int fib_count_nexthops(struct rtnexthop *rtnh, int remaining,
658 			      struct netlink_ext_ack *extack)
659 {
660 	int nhs = 0;
661 
662 	while (rtnh_ok(rtnh, remaining)) {
663 		nhs++;
664 		rtnh = rtnh_next(rtnh, &remaining);
665 	}
666 
667 	/* leftover implies invalid nexthop configuration, discard it */
668 	if (remaining > 0) {
669 		NL_SET_ERR_MSG(extack,
670 			       "Invalid nexthop configuration - extra data after nexthops");
671 		nhs = 0;
672 	}
673 
674 	return nhs;
675 }
676 
fib_gw_from_attr(__be32 * gw,struct nlattr * nla,struct netlink_ext_ack * extack)677 static int fib_gw_from_attr(__be32 *gw, struct nlattr *nla,
678 			    struct netlink_ext_ack *extack)
679 {
680 	if (nla_len(nla) < sizeof(*gw)) {
681 		NL_SET_ERR_MSG(extack, "Invalid IPv4 address in RTA_GATEWAY");
682 		return -EINVAL;
683 	}
684 
685 	*gw = nla_get_in_addr(nla);
686 
687 	return 0;
688 }
689 
690 /* 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)691 static int fib_get_nhs(struct fib_info *fi, struct rtnexthop *rtnh,
692 		       int remaining, struct fib_config *cfg,
693 		       struct netlink_ext_ack *extack)
694 {
695 	struct net *net = fi->fib_net;
696 	struct fib_config fib_cfg;
697 	struct fib_nh *nh;
698 	int ret;
699 
700 	change_nexthops(fi) {
701 		int attrlen;
702 
703 		memset(&fib_cfg, 0, sizeof(fib_cfg));
704 
705 		if (!rtnh_ok(rtnh, remaining)) {
706 			NL_SET_ERR_MSG(extack,
707 				       "Invalid nexthop configuration - extra data after nexthop");
708 			return -EINVAL;
709 		}
710 
711 		if (rtnh->rtnh_flags & (RTNH_F_DEAD | RTNH_F_LINKDOWN)) {
712 			NL_SET_ERR_MSG(extack,
713 				       "Invalid flags for nexthop - can not contain DEAD or LINKDOWN");
714 			return -EINVAL;
715 		}
716 
717 		fib_cfg.fc_flags = (cfg->fc_flags & ~0xFF) | rtnh->rtnh_flags;
718 		fib_cfg.fc_oif = rtnh->rtnh_ifindex;
719 
720 		attrlen = rtnh_attrlen(rtnh);
721 		if (attrlen > 0) {
722 			struct nlattr *nla, *nlav, *attrs = rtnh_attrs(rtnh);
723 
724 			nla = nla_find(attrs, attrlen, RTA_GATEWAY);
725 			nlav = nla_find(attrs, attrlen, RTA_VIA);
726 			if (nla && nlav) {
727 				NL_SET_ERR_MSG(extack,
728 					       "Nexthop configuration can not contain both GATEWAY and VIA");
729 				return -EINVAL;
730 			}
731 			if (nla) {
732 				ret = fib_gw_from_attr(&fib_cfg.fc_gw4, nla,
733 						       extack);
734 				if (ret)
735 					goto errout;
736 
737 				if (fib_cfg.fc_gw4)
738 					fib_cfg.fc_gw_family = AF_INET;
739 			} else if (nlav) {
740 				ret = fib_gw_from_via(&fib_cfg, nlav, extack);
741 				if (ret)
742 					goto errout;
743 			}
744 
745 			nla = nla_find(attrs, attrlen, RTA_FLOW);
746 			if (nla) {
747 				if (nla_len(nla) < sizeof(u32)) {
748 					NL_SET_ERR_MSG(extack, "Invalid RTA_FLOW");
749 					return -EINVAL;
750 				}
751 				fib_cfg.fc_flow = nla_get_u32(nla);
752 			}
753 
754 			fib_cfg.fc_encap = nla_find(attrs, attrlen, RTA_ENCAP);
755 			/* RTA_ENCAP_TYPE length checked in
756 			 * lwtunnel_valid_encap_type_attr
757 			 */
758 			nla = nla_find(attrs, attrlen, RTA_ENCAP_TYPE);
759 			if (nla)
760 				fib_cfg.fc_encap_type = nla_get_u16(nla);
761 		}
762 
763 		ret = fib_nh_init(net, nexthop_nh, &fib_cfg,
764 				  rtnh->rtnh_hops + 1, extack);
765 		if (ret)
766 			goto errout;
767 
768 		rtnh = rtnh_next(rtnh, &remaining);
769 	} endfor_nexthops(fi);
770 
771 	ret = -EINVAL;
772 	nh = fib_info_nh(fi, 0);
773 	if (cfg->fc_oif && nh->fib_nh_oif != cfg->fc_oif) {
774 		NL_SET_ERR_MSG(extack,
775 			       "Nexthop device index does not match RTA_OIF");
776 		goto errout;
777 	}
778 	if (cfg->fc_gw_family) {
779 		if (cfg->fc_gw_family != nh->fib_nh_gw_family ||
780 		    (cfg->fc_gw_family == AF_INET &&
781 		     nh->fib_nh_gw4 != cfg->fc_gw4) ||
782 		    (cfg->fc_gw_family == AF_INET6 &&
783 		     ipv6_addr_cmp(&nh->fib_nh_gw6, &cfg->fc_gw6))) {
784 			NL_SET_ERR_MSG(extack,
785 				       "Nexthop gateway does not match RTA_GATEWAY or RTA_VIA");
786 			goto errout;
787 		}
788 	}
789 #ifdef CONFIG_IP_ROUTE_CLASSID
790 	if (cfg->fc_flow && nh->nh_tclassid != cfg->fc_flow) {
791 		NL_SET_ERR_MSG(extack,
792 			       "Nexthop class id does not match RTA_FLOW");
793 		goto errout;
794 	}
795 #endif
796 	ret = 0;
797 errout:
798 	return ret;
799 }
800 
801 /* only called when fib_nh is integrated into fib_info */
fib_rebalance(struct fib_info * fi)802 static void fib_rebalance(struct fib_info *fi)
803 {
804 	int total;
805 	int w;
806 
807 	if (fib_info_num_path(fi) < 2)
808 		return;
809 
810 	total = 0;
811 	for_nexthops(fi) {
812 		if (nh->fib_nh_flags & RTNH_F_DEAD)
813 			continue;
814 
815 		if (ip_ignore_linkdown(nh->fib_nh_dev) &&
816 		    nh->fib_nh_flags & RTNH_F_LINKDOWN)
817 			continue;
818 
819 		total += nh->fib_nh_weight;
820 	} endfor_nexthops(fi);
821 
822 	w = 0;
823 	change_nexthops(fi) {
824 		int upper_bound;
825 
826 		if (nexthop_nh->fib_nh_flags & RTNH_F_DEAD) {
827 			upper_bound = -1;
828 		} else if (ip_ignore_linkdown(nexthop_nh->fib_nh_dev) &&
829 			   nexthop_nh->fib_nh_flags & RTNH_F_LINKDOWN) {
830 			upper_bound = -1;
831 		} else {
832 			w += nexthop_nh->fib_nh_weight;
833 			upper_bound = DIV_ROUND_CLOSEST_ULL((u64)w << 31,
834 							    total) - 1;
835 		}
836 
837 		atomic_set(&nexthop_nh->fib_nh_upper_bound, upper_bound);
838 	} endfor_nexthops(fi);
839 }
840 #else /* CONFIG_IP_ROUTE_MULTIPATH */
841 
fib_get_nhs(struct fib_info * fi,struct rtnexthop * rtnh,int remaining,struct fib_config * cfg,struct netlink_ext_ack * extack)842 static int fib_get_nhs(struct fib_info *fi, struct rtnexthop *rtnh,
843 		       int remaining, struct fib_config *cfg,
844 		       struct netlink_ext_ack *extack)
845 {
846 	NL_SET_ERR_MSG(extack, "Multipath support not enabled in kernel");
847 
848 	return -EINVAL;
849 }
850 
851 #define fib_rebalance(fi) do { } while (0)
852 
853 #endif /* CONFIG_IP_ROUTE_MULTIPATH */
854 
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)855 static int fib_encap_match(struct net *net, u16 encap_type,
856 			   struct nlattr *encap,
857 			   const struct fib_nh *nh,
858 			   const struct fib_config *cfg,
859 			   struct netlink_ext_ack *extack)
860 {
861 	struct lwtunnel_state *lwtstate;
862 	int ret, result = 0;
863 
864 	if (encap_type == LWTUNNEL_ENCAP_NONE)
865 		return 0;
866 
867 	ret = lwtunnel_build_state(net, encap_type, encap, AF_INET,
868 				   cfg, &lwtstate, extack);
869 	if (!ret) {
870 		result = lwtunnel_cmp_encap(lwtstate, nh->fib_nh_lws);
871 		lwtstate_free(lwtstate);
872 	}
873 
874 	return result;
875 }
876 
fib_nh_match(struct net * net,struct fib_config * cfg,struct fib_info * fi,struct netlink_ext_ack * extack)877 int fib_nh_match(struct net *net, struct fib_config *cfg, struct fib_info *fi,
878 		 struct netlink_ext_ack *extack)
879 {
880 #ifdef CONFIG_IP_ROUTE_MULTIPATH
881 	struct rtnexthop *rtnh;
882 	int remaining;
883 #endif
884 
885 	if (cfg->fc_priority && cfg->fc_priority != fi->fib_priority)
886 		return 1;
887 
888 	if (cfg->fc_nh_id) {
889 		if (fi->nh && cfg->fc_nh_id == fi->nh->id)
890 			return 0;
891 		return 1;
892 	}
893 
894 	if (fi->nh) {
895 		if (cfg->fc_oif || cfg->fc_gw_family || cfg->fc_mp)
896 			return 1;
897 		return 0;
898 	}
899 
900 	if (cfg->fc_oif || cfg->fc_gw_family) {
901 		struct fib_nh *nh;
902 
903 		nh = fib_info_nh(fi, 0);
904 		if (cfg->fc_encap) {
905 			if (fib_encap_match(net, cfg->fc_encap_type,
906 					    cfg->fc_encap, nh, cfg, extack))
907 				return 1;
908 		}
909 #ifdef CONFIG_IP_ROUTE_CLASSID
910 		if (cfg->fc_flow &&
911 		    cfg->fc_flow != nh->nh_tclassid)
912 			return 1;
913 #endif
914 		if ((cfg->fc_oif && cfg->fc_oif != nh->fib_nh_oif) ||
915 		    (cfg->fc_gw_family &&
916 		     cfg->fc_gw_family != nh->fib_nh_gw_family))
917 			return 1;
918 
919 		if (cfg->fc_gw_family == AF_INET &&
920 		    cfg->fc_gw4 != nh->fib_nh_gw4)
921 			return 1;
922 
923 		if (cfg->fc_gw_family == AF_INET6 &&
924 		    ipv6_addr_cmp(&cfg->fc_gw6, &nh->fib_nh_gw6))
925 			return 1;
926 
927 		return 0;
928 	}
929 
930 #ifdef CONFIG_IP_ROUTE_MULTIPATH
931 	if (!cfg->fc_mp)
932 		return 0;
933 
934 	rtnh = cfg->fc_mp;
935 	remaining = cfg->fc_mp_len;
936 
937 	for_nexthops(fi) {
938 		int attrlen;
939 
940 		if (!rtnh_ok(rtnh, remaining))
941 			return -EINVAL;
942 
943 		if (rtnh->rtnh_ifindex && rtnh->rtnh_ifindex != nh->fib_nh_oif)
944 			return 1;
945 
946 		attrlen = rtnh_attrlen(rtnh);
947 		if (attrlen > 0) {
948 			struct nlattr *nla, *nlav, *attrs = rtnh_attrs(rtnh);
949 			int err;
950 
951 			nla = nla_find(attrs, attrlen, RTA_GATEWAY);
952 			nlav = nla_find(attrs, attrlen, RTA_VIA);
953 			if (nla && nlav) {
954 				NL_SET_ERR_MSG(extack,
955 					       "Nexthop configuration can not contain both GATEWAY and VIA");
956 				return -EINVAL;
957 			}
958 
959 			if (nla) {
960 				__be32 gw;
961 
962 				err = fib_gw_from_attr(&gw, nla, extack);
963 				if (err)
964 					return err;
965 
966 				if (nh->fib_nh_gw_family != AF_INET ||
967 				    gw != nh->fib_nh_gw4)
968 					return 1;
969 			} else if (nlav) {
970 				struct fib_config cfg2;
971 
972 				err = fib_gw_from_via(&cfg2, nlav, extack);
973 				if (err)
974 					return err;
975 
976 				switch (nh->fib_nh_gw_family) {
977 				case AF_INET:
978 					if (cfg2.fc_gw_family != AF_INET ||
979 					    cfg2.fc_gw4 != nh->fib_nh_gw4)
980 						return 1;
981 					break;
982 				case AF_INET6:
983 					if (cfg2.fc_gw_family != AF_INET6 ||
984 					    ipv6_addr_cmp(&cfg2.fc_gw6,
985 							  &nh->fib_nh_gw6))
986 						return 1;
987 					break;
988 				}
989 			}
990 
991 #ifdef CONFIG_IP_ROUTE_CLASSID
992 			nla = nla_find(attrs, attrlen, RTA_FLOW);
993 			if (nla) {
994 				if (nla_len(nla) < sizeof(u32)) {
995 					NL_SET_ERR_MSG(extack, "Invalid RTA_FLOW");
996 					return -EINVAL;
997 				}
998 				if (nla_get_u32(nla) != nh->nh_tclassid)
999 					return 1;
1000 			}
1001 #endif
1002 		}
1003 
1004 		rtnh = rtnh_next(rtnh, &remaining);
1005 	} endfor_nexthops(fi);
1006 #endif
1007 	return 0;
1008 }
1009 
fib_metrics_match(struct fib_config * cfg,struct fib_info * fi)1010 bool fib_metrics_match(struct fib_config *cfg, struct fib_info *fi)
1011 {
1012 	struct nlattr *nla;
1013 	int remaining;
1014 
1015 	if (!cfg->fc_mx)
1016 		return true;
1017 
1018 	nla_for_each_attr(nla, cfg->fc_mx, cfg->fc_mx_len, remaining) {
1019 		int type = nla_type(nla);
1020 		u32 fi_val, val;
1021 
1022 		if (!type)
1023 			continue;
1024 		if (type > RTAX_MAX)
1025 			return false;
1026 
1027 		type = array_index_nospec(type, RTAX_MAX + 1);
1028 		if (type == RTAX_CC_ALGO) {
1029 			char tmp[TCP_CA_NAME_MAX];
1030 			bool ecn_ca = false;
1031 
1032 			nla_strscpy(tmp, nla, sizeof(tmp));
1033 			val = tcp_ca_get_key_by_name(fi->fib_net, tmp, &ecn_ca);
1034 		} else {
1035 			if (nla_len(nla) != sizeof(u32))
1036 				return false;
1037 			val = nla_get_u32(nla);
1038 		}
1039 
1040 		fi_val = fi->fib_metrics->metrics[type - 1];
1041 		if (type == RTAX_FEATURES)
1042 			fi_val &= ~DST_FEATURE_ECN_CA;
1043 
1044 		if (fi_val != val)
1045 			return false;
1046 	}
1047 
1048 	return true;
1049 }
1050 
fib_check_nh_v6_gw(struct net * net,struct fib_nh * nh,u32 table,struct netlink_ext_ack * extack)1051 static int fib_check_nh_v6_gw(struct net *net, struct fib_nh *nh,
1052 			      u32 table, struct netlink_ext_ack *extack)
1053 {
1054 	struct fib6_config cfg = {
1055 		.fc_table = table,
1056 		.fc_flags = nh->fib_nh_flags | RTF_GATEWAY,
1057 		.fc_ifindex = nh->fib_nh_oif,
1058 		.fc_gateway = nh->fib_nh_gw6,
1059 	};
1060 	struct fib6_nh fib6_nh = {};
1061 	int err;
1062 
1063 	err = ipv6_stub->fib6_nh_init(net, &fib6_nh, &cfg, GFP_KERNEL, extack);
1064 	if (!err) {
1065 		nh->fib_nh_dev = fib6_nh.fib_nh_dev;
1066 		netdev_hold(nh->fib_nh_dev, &nh->fib_nh_dev_tracker,
1067 			    GFP_KERNEL);
1068 		nh->fib_nh_oif = nh->fib_nh_dev->ifindex;
1069 		nh->fib_nh_scope = RT_SCOPE_LINK;
1070 
1071 		ipv6_stub->fib6_nh_release(&fib6_nh);
1072 	}
1073 
1074 	return err;
1075 }
1076 
1077 /*
1078  * Picture
1079  * -------
1080  *
1081  * Semantics of nexthop is very messy by historical reasons.
1082  * We have to take into account, that:
1083  * a) gateway can be actually local interface address,
1084  *    so that gatewayed route is direct.
1085  * b) gateway must be on-link address, possibly
1086  *    described not by an ifaddr, but also by a direct route.
1087  * c) If both gateway and interface are specified, they should not
1088  *    contradict.
1089  * d) If we use tunnel routes, gateway could be not on-link.
1090  *
1091  * Attempt to reconcile all of these (alas, self-contradictory) conditions
1092  * results in pretty ugly and hairy code with obscure logic.
1093  *
1094  * I chose to generalized it instead, so that the size
1095  * of code does not increase practically, but it becomes
1096  * much more general.
1097  * Every prefix is assigned a "scope" value: "host" is local address,
1098  * "link" is direct route,
1099  * [ ... "site" ... "interior" ... ]
1100  * and "universe" is true gateway route with global meaning.
1101  *
1102  * Every prefix refers to a set of "nexthop"s (gw, oif),
1103  * where gw must have narrower scope. This recursion stops
1104  * when gw has LOCAL scope or if "nexthop" is declared ONLINK,
1105  * which means that gw is forced to be on link.
1106  *
1107  * Code is still hairy, but now it is apparently logically
1108  * consistent and very flexible. F.e. as by-product it allows
1109  * to co-exists in peace independent exterior and interior
1110  * routing processes.
1111  *
1112  * Normally it looks as following.
1113  *
1114  * {universe prefix}  -> (gw, oif) [scope link]
1115  *		  |
1116  *		  |-> {link prefix} -> (gw, oif) [scope local]
1117  *					|
1118  *					|-> {local prefix} (terminal node)
1119  */
fib_check_nh_v4_gw(struct net * net,struct fib_nh * nh,u32 table,u8 scope,struct netlink_ext_ack * extack)1120 static int fib_check_nh_v4_gw(struct net *net, struct fib_nh *nh, u32 table,
1121 			      u8 scope, struct netlink_ext_ack *extack)
1122 {
1123 	struct net_device *dev;
1124 	struct fib_result res;
1125 	int err = 0;
1126 
1127 	if (nh->fib_nh_flags & RTNH_F_ONLINK) {
1128 		unsigned int addr_type;
1129 
1130 		if (scope >= RT_SCOPE_LINK) {
1131 			NL_SET_ERR_MSG(extack, "Nexthop has invalid scope");
1132 			return -EINVAL;
1133 		}
1134 		dev = __dev_get_by_index(net, nh->fib_nh_oif);
1135 		if (!dev) {
1136 			NL_SET_ERR_MSG(extack, "Nexthop device required for onlink");
1137 			return -ENODEV;
1138 		}
1139 		if (!(dev->flags & IFF_UP)) {
1140 			NL_SET_ERR_MSG(extack, "Nexthop device is not up");
1141 			return -ENETDOWN;
1142 		}
1143 		addr_type = inet_addr_type_dev_table(net, dev, nh->fib_nh_gw4);
1144 		if (addr_type != RTN_UNICAST) {
1145 			NL_SET_ERR_MSG(extack, "Nexthop has invalid gateway");
1146 			return -EINVAL;
1147 		}
1148 		if (!netif_carrier_ok(dev))
1149 			nh->fib_nh_flags |= RTNH_F_LINKDOWN;
1150 		nh->fib_nh_dev = dev;
1151 		netdev_hold(dev, &nh->fib_nh_dev_tracker, GFP_ATOMIC);
1152 		nh->fib_nh_scope = RT_SCOPE_LINK;
1153 		return 0;
1154 	}
1155 	rcu_read_lock();
1156 	{
1157 		struct fib_table *tbl = NULL;
1158 		struct flowi4 fl4 = {
1159 			.daddr = nh->fib_nh_gw4,
1160 			.flowi4_scope = scope + 1,
1161 			.flowi4_oif = nh->fib_nh_oif,
1162 			.flowi4_iif = LOOPBACK_IFINDEX,
1163 		};
1164 
1165 		/* It is not necessary, but requires a bit of thinking */
1166 		if (fl4.flowi4_scope < RT_SCOPE_LINK)
1167 			fl4.flowi4_scope = RT_SCOPE_LINK;
1168 
1169 		if (table && table != RT_TABLE_MAIN)
1170 			tbl = fib_get_table(net, table);
1171 
1172 		if (tbl)
1173 			err = fib_table_lookup(tbl, &fl4, &res,
1174 					       FIB_LOOKUP_IGNORE_LINKSTATE |
1175 					       FIB_LOOKUP_NOREF);
1176 
1177 		/* on error or if no table given do full lookup. This
1178 		 * is needed for example when nexthops are in the local
1179 		 * table rather than the given table
1180 		 */
1181 		if (!tbl || err) {
1182 			err = fib_lookup(net, &fl4, &res,
1183 					 FIB_LOOKUP_IGNORE_LINKSTATE);
1184 		}
1185 
1186 		if (err) {
1187 			NL_SET_ERR_MSG(extack, "Nexthop has invalid gateway");
1188 			goto out;
1189 		}
1190 	}
1191 
1192 	err = -EINVAL;
1193 	if (res.type != RTN_UNICAST && res.type != RTN_LOCAL) {
1194 		NL_SET_ERR_MSG(extack, "Nexthop has invalid gateway");
1195 		goto out;
1196 	}
1197 	nh->fib_nh_scope = res.scope;
1198 	nh->fib_nh_oif = FIB_RES_OIF(res);
1199 	nh->fib_nh_dev = dev = FIB_RES_DEV(res);
1200 	if (!dev) {
1201 		NL_SET_ERR_MSG(extack,
1202 			       "No egress device for nexthop gateway");
1203 		goto out;
1204 	}
1205 	netdev_hold(dev, &nh->fib_nh_dev_tracker, GFP_ATOMIC);
1206 	if (!netif_carrier_ok(dev))
1207 		nh->fib_nh_flags |= RTNH_F_LINKDOWN;
1208 	err = (dev->flags & IFF_UP) ? 0 : -ENETDOWN;
1209 out:
1210 	rcu_read_unlock();
1211 	return err;
1212 }
1213 
fib_check_nh_nongw(struct net * net,struct fib_nh * nh,struct netlink_ext_ack * extack)1214 static int fib_check_nh_nongw(struct net *net, struct fib_nh *nh,
1215 			      struct netlink_ext_ack *extack)
1216 {
1217 	struct in_device *in_dev;
1218 	int err;
1219 
1220 	if (nh->fib_nh_flags & (RTNH_F_PERVASIVE | RTNH_F_ONLINK)) {
1221 		NL_SET_ERR_MSG(extack,
1222 			       "Invalid flags for nexthop - PERVASIVE and ONLINK can not be set");
1223 		return -EINVAL;
1224 	}
1225 
1226 	rcu_read_lock();
1227 
1228 	err = -ENODEV;
1229 	in_dev = inetdev_by_index(net, nh->fib_nh_oif);
1230 	if (!in_dev)
1231 		goto out;
1232 	err = -ENETDOWN;
1233 	if (!(in_dev->dev->flags & IFF_UP)) {
1234 		NL_SET_ERR_MSG(extack, "Device for nexthop is not up");
1235 		goto out;
1236 	}
1237 
1238 	nh->fib_nh_dev = in_dev->dev;
1239 	netdev_hold(nh->fib_nh_dev, &nh->fib_nh_dev_tracker, GFP_ATOMIC);
1240 	nh->fib_nh_scope = RT_SCOPE_HOST;
1241 	if (!netif_carrier_ok(nh->fib_nh_dev))
1242 		nh->fib_nh_flags |= RTNH_F_LINKDOWN;
1243 	err = 0;
1244 out:
1245 	rcu_read_unlock();
1246 	return err;
1247 }
1248 
fib_check_nh(struct net * net,struct fib_nh * nh,u32 table,u8 scope,struct netlink_ext_ack * extack)1249 int fib_check_nh(struct net *net, struct fib_nh *nh, u32 table, u8 scope,
1250 		 struct netlink_ext_ack *extack)
1251 {
1252 	int err;
1253 
1254 	if (nh->fib_nh_gw_family == AF_INET)
1255 		err = fib_check_nh_v4_gw(net, nh, table, scope, extack);
1256 	else if (nh->fib_nh_gw_family == AF_INET6)
1257 		err = fib_check_nh_v6_gw(net, nh, table, extack);
1258 	else
1259 		err = fib_check_nh_nongw(net, nh, extack);
1260 
1261 	return err;
1262 }
1263 
1264 static struct hlist_head *
fib_info_laddrhash_bucket(const struct net * net,__be32 val)1265 fib_info_laddrhash_bucket(const struct net *net, __be32 val)
1266 {
1267 	u32 slot = hash_32(net_hash_mix(net) ^ (__force u32)val,
1268 			   fib_info_hash_bits);
1269 
1270 	return &fib_info_laddrhash[slot];
1271 }
1272 
fib_info_hash_move(struct hlist_head * new_info_hash,struct hlist_head * new_laddrhash,unsigned int new_size)1273 static void fib_info_hash_move(struct hlist_head *new_info_hash,
1274 			       struct hlist_head *new_laddrhash,
1275 			       unsigned int new_size)
1276 {
1277 	struct hlist_head *old_info_hash, *old_laddrhash;
1278 	unsigned int old_size = fib_info_hash_size;
1279 	unsigned int i;
1280 
1281 	spin_lock_bh(&fib_info_lock);
1282 	old_info_hash = fib_info_hash;
1283 	old_laddrhash = fib_info_laddrhash;
1284 	fib_info_hash_size = new_size;
1285 	fib_info_hash_bits = ilog2(new_size);
1286 
1287 	for (i = 0; i < old_size; i++) {
1288 		struct hlist_head *head = &fib_info_hash[i];
1289 		struct hlist_node *n;
1290 		struct fib_info *fi;
1291 
1292 		hlist_for_each_entry_safe(fi, n, head, fib_hash) {
1293 			struct hlist_head *dest;
1294 			unsigned int new_hash;
1295 
1296 			new_hash = fib_info_hashfn(fi);
1297 			dest = &new_info_hash[new_hash];
1298 			hlist_add_head(&fi->fib_hash, dest);
1299 		}
1300 	}
1301 	fib_info_hash = new_info_hash;
1302 
1303 	fib_info_laddrhash = new_laddrhash;
1304 	for (i = 0; i < old_size; i++) {
1305 		struct hlist_head *lhead = &old_laddrhash[i];
1306 		struct hlist_node *n;
1307 		struct fib_info *fi;
1308 
1309 		hlist_for_each_entry_safe(fi, n, lhead, fib_lhash) {
1310 			struct hlist_head *ldest;
1311 
1312 			ldest = fib_info_laddrhash_bucket(fi->fib_net,
1313 							  fi->fib_prefsrc);
1314 			hlist_add_head(&fi->fib_lhash, ldest);
1315 		}
1316 	}
1317 
1318 	spin_unlock_bh(&fib_info_lock);
1319 
1320 	kvfree(old_info_hash);
1321 	kvfree(old_laddrhash);
1322 }
1323 
fib_info_update_nhc_saddr(struct net * net,struct fib_nh_common * nhc,unsigned char scope)1324 __be32 fib_info_update_nhc_saddr(struct net *net, struct fib_nh_common *nhc,
1325 				 unsigned char scope)
1326 {
1327 	struct fib_nh *nh;
1328 	__be32 saddr;
1329 
1330 	if (nhc->nhc_family != AF_INET)
1331 		return inet_select_addr(nhc->nhc_dev, 0, scope);
1332 
1333 	nh = container_of(nhc, struct fib_nh, nh_common);
1334 	saddr = inet_select_addr(nh->fib_nh_dev, nh->fib_nh_gw4, scope);
1335 
1336 	WRITE_ONCE(nh->nh_saddr, saddr);
1337 	WRITE_ONCE(nh->nh_saddr_genid, atomic_read(&net->ipv4.dev_addr_genid));
1338 
1339 	return saddr;
1340 }
1341 
fib_result_prefsrc(struct net * net,struct fib_result * res)1342 __be32 fib_result_prefsrc(struct net *net, struct fib_result *res)
1343 {
1344 	struct fib_nh_common *nhc = res->nhc;
1345 
1346 	if (res->fi->fib_prefsrc)
1347 		return res->fi->fib_prefsrc;
1348 
1349 	if (nhc->nhc_family == AF_INET) {
1350 		struct fib_nh *nh;
1351 
1352 		nh = container_of(nhc, struct fib_nh, nh_common);
1353 		if (READ_ONCE(nh->nh_saddr_genid) ==
1354 		    atomic_read(&net->ipv4.dev_addr_genid))
1355 			return READ_ONCE(nh->nh_saddr);
1356 	}
1357 
1358 	return fib_info_update_nhc_saddr(net, nhc, res->fi->fib_scope);
1359 }
1360 
fib_valid_prefsrc(struct fib_config * cfg,__be32 fib_prefsrc)1361 static bool fib_valid_prefsrc(struct fib_config *cfg, __be32 fib_prefsrc)
1362 {
1363 	if (cfg->fc_type != RTN_LOCAL || !cfg->fc_dst ||
1364 	    fib_prefsrc != cfg->fc_dst) {
1365 		u32 tb_id = cfg->fc_table;
1366 		int rc;
1367 
1368 		if (tb_id == RT_TABLE_MAIN)
1369 			tb_id = RT_TABLE_LOCAL;
1370 
1371 		rc = inet_addr_type_table(cfg->fc_nlinfo.nl_net,
1372 					  fib_prefsrc, tb_id);
1373 
1374 		if (rc != RTN_LOCAL && tb_id != RT_TABLE_LOCAL) {
1375 			rc = inet_addr_type_table(cfg->fc_nlinfo.nl_net,
1376 						  fib_prefsrc, RT_TABLE_LOCAL);
1377 		}
1378 
1379 		if (rc != RTN_LOCAL)
1380 			return false;
1381 	}
1382 	return true;
1383 }
1384 
fib_create_info(struct fib_config * cfg,struct netlink_ext_ack * extack)1385 struct fib_info *fib_create_info(struct fib_config *cfg,
1386 				 struct netlink_ext_ack *extack)
1387 {
1388 	int err;
1389 	struct fib_info *fi = NULL;
1390 	struct nexthop *nh = NULL;
1391 	struct fib_info *ofi;
1392 	int nhs = 1;
1393 	struct net *net = cfg->fc_nlinfo.nl_net;
1394 
1395 	if (cfg->fc_type > RTN_MAX)
1396 		goto err_inval;
1397 
1398 	/* Fast check to catch the most weird cases */
1399 	if (fib_props[cfg->fc_type].scope > cfg->fc_scope) {
1400 		NL_SET_ERR_MSG(extack, "Invalid scope");
1401 		goto err_inval;
1402 	}
1403 
1404 	if (cfg->fc_flags & (RTNH_F_DEAD | RTNH_F_LINKDOWN)) {
1405 		NL_SET_ERR_MSG(extack,
1406 			       "Invalid rtm_flags - can not contain DEAD or LINKDOWN");
1407 		goto err_inval;
1408 	}
1409 
1410 	if (cfg->fc_nh_id) {
1411 		if (!cfg->fc_mx) {
1412 			fi = fib_find_info_nh(net, cfg);
1413 			if (fi) {
1414 				refcount_inc(&fi->fib_treeref);
1415 				return fi;
1416 			}
1417 		}
1418 
1419 		nh = nexthop_find_by_id(net, cfg->fc_nh_id);
1420 		if (!nh) {
1421 			NL_SET_ERR_MSG(extack, "Nexthop id does not exist");
1422 			goto err_inval;
1423 		}
1424 		nhs = 0;
1425 	}
1426 
1427 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1428 	if (cfg->fc_mp) {
1429 		nhs = fib_count_nexthops(cfg->fc_mp, cfg->fc_mp_len, extack);
1430 		if (nhs == 0)
1431 			goto err_inval;
1432 	}
1433 #endif
1434 
1435 	err = -ENOBUFS;
1436 
1437 	/* Paired with WRITE_ONCE() in fib_release_info() */
1438 	if (READ_ONCE(fib_info_cnt) >= fib_info_hash_size) {
1439 		unsigned int new_size = fib_info_hash_size << 1;
1440 		struct hlist_head *new_info_hash;
1441 		struct hlist_head *new_laddrhash;
1442 		size_t bytes;
1443 
1444 		if (!new_size)
1445 			new_size = 16;
1446 		bytes = (size_t)new_size * sizeof(struct hlist_head *);
1447 		new_info_hash = kvzalloc(bytes, GFP_KERNEL);
1448 		new_laddrhash = kvzalloc(bytes, GFP_KERNEL);
1449 		if (!new_info_hash || !new_laddrhash) {
1450 			kvfree(new_info_hash);
1451 			kvfree(new_laddrhash);
1452 		} else {
1453 			fib_info_hash_move(new_info_hash, new_laddrhash, new_size);
1454 		}
1455 		if (!fib_info_hash_size)
1456 			goto failure;
1457 	}
1458 
1459 	fi = kzalloc(struct_size(fi, fib_nh, nhs), GFP_KERNEL);
1460 	if (!fi)
1461 		goto failure;
1462 	fi->fib_metrics = ip_fib_metrics_init(fi->fib_net, cfg->fc_mx,
1463 					      cfg->fc_mx_len, extack);
1464 	if (IS_ERR(fi->fib_metrics)) {
1465 		err = PTR_ERR(fi->fib_metrics);
1466 		kfree(fi);
1467 		return ERR_PTR(err);
1468 	}
1469 
1470 	fi->fib_net = net;
1471 	fi->fib_protocol = cfg->fc_protocol;
1472 	fi->fib_scope = cfg->fc_scope;
1473 	fi->fib_flags = cfg->fc_flags;
1474 	fi->fib_priority = cfg->fc_priority;
1475 	fi->fib_prefsrc = cfg->fc_prefsrc;
1476 	fi->fib_type = cfg->fc_type;
1477 	fi->fib_tb_id = cfg->fc_table;
1478 
1479 	fi->fib_nhs = nhs;
1480 	if (nh) {
1481 		if (!nexthop_get(nh)) {
1482 			NL_SET_ERR_MSG(extack, "Nexthop has been deleted");
1483 			err = -EINVAL;
1484 		} else {
1485 			err = 0;
1486 			fi->nh = nh;
1487 		}
1488 	} else {
1489 		change_nexthops(fi) {
1490 			nexthop_nh->nh_parent = fi;
1491 		} endfor_nexthops(fi)
1492 
1493 		if (cfg->fc_mp)
1494 			err = fib_get_nhs(fi, cfg->fc_mp, cfg->fc_mp_len, cfg,
1495 					  extack);
1496 		else
1497 			err = fib_nh_init(net, fi->fib_nh, cfg, 1, extack);
1498 	}
1499 
1500 	if (err != 0)
1501 		goto failure;
1502 
1503 	if (fib_props[cfg->fc_type].error) {
1504 		if (cfg->fc_gw_family || cfg->fc_oif || cfg->fc_mp) {
1505 			NL_SET_ERR_MSG(extack,
1506 				       "Gateway, device and multipath can not be specified for this route type");
1507 			goto err_inval;
1508 		}
1509 		goto link_it;
1510 	} else {
1511 		switch (cfg->fc_type) {
1512 		case RTN_UNICAST:
1513 		case RTN_LOCAL:
1514 		case RTN_BROADCAST:
1515 		case RTN_ANYCAST:
1516 		case RTN_MULTICAST:
1517 			break;
1518 		default:
1519 			NL_SET_ERR_MSG(extack, "Invalid route type");
1520 			goto err_inval;
1521 		}
1522 	}
1523 
1524 	if (cfg->fc_scope > RT_SCOPE_HOST) {
1525 		NL_SET_ERR_MSG(extack, "Invalid scope");
1526 		goto err_inval;
1527 	}
1528 
1529 	if (fi->nh) {
1530 		err = fib_check_nexthop(fi->nh, cfg->fc_scope, extack);
1531 		if (err)
1532 			goto failure;
1533 	} else if (cfg->fc_scope == RT_SCOPE_HOST) {
1534 		struct fib_nh *nh = fi->fib_nh;
1535 
1536 		/* Local address is added. */
1537 		if (nhs != 1) {
1538 			NL_SET_ERR_MSG(extack,
1539 				       "Route with host scope can not have multiple nexthops");
1540 			goto err_inval;
1541 		}
1542 		if (nh->fib_nh_gw_family) {
1543 			NL_SET_ERR_MSG(extack,
1544 				       "Route with host scope can not have a gateway");
1545 			goto err_inval;
1546 		}
1547 		nh->fib_nh_scope = RT_SCOPE_NOWHERE;
1548 		nh->fib_nh_dev = dev_get_by_index(net, nh->fib_nh_oif);
1549 		err = -ENODEV;
1550 		if (!nh->fib_nh_dev)
1551 			goto failure;
1552 		netdev_tracker_alloc(nh->fib_nh_dev, &nh->fib_nh_dev_tracker,
1553 				     GFP_KERNEL);
1554 	} else {
1555 		int linkdown = 0;
1556 
1557 		change_nexthops(fi) {
1558 			err = fib_check_nh(cfg->fc_nlinfo.nl_net, nexthop_nh,
1559 					   cfg->fc_table, cfg->fc_scope,
1560 					   extack);
1561 			if (err != 0)
1562 				goto failure;
1563 			if (nexthop_nh->fib_nh_flags & RTNH_F_LINKDOWN)
1564 				linkdown++;
1565 		} endfor_nexthops(fi)
1566 		if (linkdown == fi->fib_nhs)
1567 			fi->fib_flags |= RTNH_F_LINKDOWN;
1568 	}
1569 
1570 	if (fi->fib_prefsrc && !fib_valid_prefsrc(cfg, fi->fib_prefsrc)) {
1571 		NL_SET_ERR_MSG(extack, "Invalid prefsrc address");
1572 		goto err_inval;
1573 	}
1574 
1575 	if (!fi->nh) {
1576 		change_nexthops(fi) {
1577 			fib_info_update_nhc_saddr(net, &nexthop_nh->nh_common,
1578 						  fi->fib_scope);
1579 			if (nexthop_nh->fib_nh_gw_family == AF_INET6)
1580 				fi->fib_nh_is_v6 = true;
1581 		} endfor_nexthops(fi)
1582 
1583 		fib_rebalance(fi);
1584 	}
1585 
1586 link_it:
1587 	ofi = fib_find_info(fi);
1588 	if (ofi) {
1589 		/* fib_table_lookup() should not see @fi yet. */
1590 		fi->fib_dead = 1;
1591 		free_fib_info(fi);
1592 		refcount_inc(&ofi->fib_treeref);
1593 		return ofi;
1594 	}
1595 
1596 	refcount_set(&fi->fib_treeref, 1);
1597 	refcount_set(&fi->fib_clntref, 1);
1598 	spin_lock_bh(&fib_info_lock);
1599 	fib_info_cnt++;
1600 	hlist_add_head(&fi->fib_hash,
1601 		       &fib_info_hash[fib_info_hashfn(fi)]);
1602 	if (fi->fib_prefsrc) {
1603 		struct hlist_head *head;
1604 
1605 		head = fib_info_laddrhash_bucket(net, fi->fib_prefsrc);
1606 		hlist_add_head(&fi->fib_lhash, head);
1607 	}
1608 	if (fi->nh) {
1609 		list_add(&fi->nh_list, &nh->fi_list);
1610 	} else {
1611 		change_nexthops(fi) {
1612 			struct hlist_head *head;
1613 
1614 			if (!nexthop_nh->fib_nh_dev)
1615 				continue;
1616 			head = fib_info_devhash_bucket(nexthop_nh->fib_nh_dev);
1617 			hlist_add_head(&nexthop_nh->nh_hash, head);
1618 		} endfor_nexthops(fi)
1619 	}
1620 	spin_unlock_bh(&fib_info_lock);
1621 	return fi;
1622 
1623 err_inval:
1624 	err = -EINVAL;
1625 
1626 failure:
1627 	if (fi) {
1628 		/* fib_table_lookup() should not see @fi yet. */
1629 		fi->fib_dead = 1;
1630 		free_fib_info(fi);
1631 	}
1632 
1633 	return ERR_PTR(err);
1634 }
1635 
fib_nexthop_info(struct sk_buff * skb,const struct fib_nh_common * nhc,u8 rt_family,unsigned char * flags,bool skip_oif)1636 int fib_nexthop_info(struct sk_buff *skb, const struct fib_nh_common *nhc,
1637 		     u8 rt_family, unsigned char *flags, bool skip_oif)
1638 {
1639 	if (nhc->nhc_flags & RTNH_F_DEAD)
1640 		*flags |= RTNH_F_DEAD;
1641 
1642 	if (nhc->nhc_flags & RTNH_F_LINKDOWN) {
1643 		*flags |= RTNH_F_LINKDOWN;
1644 
1645 		rcu_read_lock();
1646 		switch (nhc->nhc_family) {
1647 		case AF_INET:
1648 			if (ip_ignore_linkdown(nhc->nhc_dev))
1649 				*flags |= RTNH_F_DEAD;
1650 			break;
1651 		case AF_INET6:
1652 			if (ip6_ignore_linkdown(nhc->nhc_dev))
1653 				*flags |= RTNH_F_DEAD;
1654 			break;
1655 		}
1656 		rcu_read_unlock();
1657 	}
1658 
1659 	switch (nhc->nhc_gw_family) {
1660 	case AF_INET:
1661 		if (nla_put_in_addr(skb, RTA_GATEWAY, nhc->nhc_gw.ipv4))
1662 			goto nla_put_failure;
1663 		break;
1664 	case AF_INET6:
1665 		/* if gateway family does not match nexthop family
1666 		 * gateway is encoded as RTA_VIA
1667 		 */
1668 		if (rt_family != nhc->nhc_gw_family) {
1669 			int alen = sizeof(struct in6_addr);
1670 			struct nlattr *nla;
1671 			struct rtvia *via;
1672 
1673 			nla = nla_reserve(skb, RTA_VIA, alen + 2);
1674 			if (!nla)
1675 				goto nla_put_failure;
1676 
1677 			via = nla_data(nla);
1678 			via->rtvia_family = AF_INET6;
1679 			memcpy(via->rtvia_addr, &nhc->nhc_gw.ipv6, alen);
1680 		} else if (nla_put_in6_addr(skb, RTA_GATEWAY,
1681 					    &nhc->nhc_gw.ipv6) < 0) {
1682 			goto nla_put_failure;
1683 		}
1684 		break;
1685 	}
1686 
1687 	*flags |= (nhc->nhc_flags &
1688 		   (RTNH_F_ONLINK | RTNH_F_OFFLOAD | RTNH_F_TRAP));
1689 
1690 	if (!skip_oif && nhc->nhc_dev &&
1691 	    nla_put_u32(skb, RTA_OIF, nhc->nhc_dev->ifindex))
1692 		goto nla_put_failure;
1693 
1694 	if (nhc->nhc_lwtstate &&
1695 	    lwtunnel_fill_encap(skb, nhc->nhc_lwtstate,
1696 				RTA_ENCAP, RTA_ENCAP_TYPE) < 0)
1697 		goto nla_put_failure;
1698 
1699 	return 0;
1700 
1701 nla_put_failure:
1702 	return -EMSGSIZE;
1703 }
1704 EXPORT_SYMBOL_GPL(fib_nexthop_info);
1705 
1706 #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)1707 int fib_add_nexthop(struct sk_buff *skb, const struct fib_nh_common *nhc,
1708 		    int nh_weight, u8 rt_family, u32 nh_tclassid)
1709 {
1710 	const struct net_device *dev = nhc->nhc_dev;
1711 	struct rtnexthop *rtnh;
1712 	unsigned char flags = 0;
1713 
1714 	rtnh = nla_reserve_nohdr(skb, sizeof(*rtnh));
1715 	if (!rtnh)
1716 		goto nla_put_failure;
1717 
1718 	rtnh->rtnh_hops = nh_weight - 1;
1719 	rtnh->rtnh_ifindex = dev ? dev->ifindex : 0;
1720 
1721 	if (fib_nexthop_info(skb, nhc, rt_family, &flags, true) < 0)
1722 		goto nla_put_failure;
1723 
1724 	rtnh->rtnh_flags = flags;
1725 
1726 	if (nh_tclassid && nla_put_u32(skb, RTA_FLOW, nh_tclassid))
1727 		goto nla_put_failure;
1728 
1729 	/* length of rtnetlink header + attributes */
1730 	rtnh->rtnh_len = nlmsg_get_pos(skb) - (void *)rtnh;
1731 
1732 	return 0;
1733 
1734 nla_put_failure:
1735 	return -EMSGSIZE;
1736 }
1737 EXPORT_SYMBOL_GPL(fib_add_nexthop);
1738 #endif
1739 
1740 #ifdef CONFIG_IP_ROUTE_MULTIPATH
fib_add_multipath(struct sk_buff * skb,struct fib_info * fi)1741 static int fib_add_multipath(struct sk_buff *skb, struct fib_info *fi)
1742 {
1743 	struct nlattr *mp;
1744 
1745 	mp = nla_nest_start_noflag(skb, RTA_MULTIPATH);
1746 	if (!mp)
1747 		goto nla_put_failure;
1748 
1749 	if (unlikely(fi->nh)) {
1750 		if (nexthop_mpath_fill_node(skb, fi->nh, AF_INET) < 0)
1751 			goto nla_put_failure;
1752 		goto mp_end;
1753 	}
1754 
1755 	for_nexthops(fi) {
1756 		u32 nh_tclassid = 0;
1757 #ifdef CONFIG_IP_ROUTE_CLASSID
1758 		nh_tclassid = nh->nh_tclassid;
1759 #endif
1760 		if (fib_add_nexthop(skb, &nh->nh_common, nh->fib_nh_weight,
1761 				    AF_INET, nh_tclassid) < 0)
1762 			goto nla_put_failure;
1763 	} endfor_nexthops(fi);
1764 
1765 mp_end:
1766 	nla_nest_end(skb, mp);
1767 
1768 	return 0;
1769 
1770 nla_put_failure:
1771 	return -EMSGSIZE;
1772 }
1773 #else
fib_add_multipath(struct sk_buff * skb,struct fib_info * fi)1774 static int fib_add_multipath(struct sk_buff *skb, struct fib_info *fi)
1775 {
1776 	return 0;
1777 }
1778 #endif
1779 
fib_dump_info(struct sk_buff * skb,u32 portid,u32 seq,int event,const struct fib_rt_info * fri,unsigned int flags)1780 int fib_dump_info(struct sk_buff *skb, u32 portid, u32 seq, int event,
1781 		  const struct fib_rt_info *fri, unsigned int flags)
1782 {
1783 	unsigned int nhs = fib_info_num_path(fri->fi);
1784 	struct fib_info *fi = fri->fi;
1785 	u32 tb_id = fri->tb_id;
1786 	struct nlmsghdr *nlh;
1787 	struct rtmsg *rtm;
1788 
1789 	nlh = nlmsg_put(skb, portid, seq, event, sizeof(*rtm), flags);
1790 	if (!nlh)
1791 		return -EMSGSIZE;
1792 
1793 	rtm = nlmsg_data(nlh);
1794 	rtm->rtm_family = AF_INET;
1795 	rtm->rtm_dst_len = fri->dst_len;
1796 	rtm->rtm_src_len = 0;
1797 	rtm->rtm_tos = inet_dscp_to_dsfield(fri->dscp);
1798 	if (tb_id < 256)
1799 		rtm->rtm_table = tb_id;
1800 	else
1801 		rtm->rtm_table = RT_TABLE_COMPAT;
1802 	if (nla_put_u32(skb, RTA_TABLE, tb_id))
1803 		goto nla_put_failure;
1804 	rtm->rtm_type = fri->type;
1805 	rtm->rtm_flags = fi->fib_flags;
1806 	rtm->rtm_scope = fi->fib_scope;
1807 	rtm->rtm_protocol = fi->fib_protocol;
1808 
1809 	if (rtm->rtm_dst_len &&
1810 	    nla_put_in_addr(skb, RTA_DST, fri->dst))
1811 		goto nla_put_failure;
1812 	if (fi->fib_priority &&
1813 	    nla_put_u32(skb, RTA_PRIORITY, fi->fib_priority))
1814 		goto nla_put_failure;
1815 	if (rtnetlink_put_metrics(skb, fi->fib_metrics->metrics) < 0)
1816 		goto nla_put_failure;
1817 
1818 	if (fi->fib_prefsrc &&
1819 	    nla_put_in_addr(skb, RTA_PREFSRC, fi->fib_prefsrc))
1820 		goto nla_put_failure;
1821 
1822 	if (fi->nh) {
1823 		if (nla_put_u32(skb, RTA_NH_ID, fi->nh->id))
1824 			goto nla_put_failure;
1825 		if (nexthop_is_blackhole(fi->nh))
1826 			rtm->rtm_type = RTN_BLACKHOLE;
1827 		if (!READ_ONCE(fi->fib_net->ipv4.sysctl_nexthop_compat_mode))
1828 			goto offload;
1829 	}
1830 
1831 	if (nhs == 1) {
1832 		const struct fib_nh_common *nhc = fib_info_nhc(fi, 0);
1833 		unsigned char flags = 0;
1834 
1835 		if (fib_nexthop_info(skb, nhc, AF_INET, &flags, false) < 0)
1836 			goto nla_put_failure;
1837 
1838 		rtm->rtm_flags = flags;
1839 #ifdef CONFIG_IP_ROUTE_CLASSID
1840 		if (nhc->nhc_family == AF_INET) {
1841 			struct fib_nh *nh;
1842 
1843 			nh = container_of(nhc, struct fib_nh, nh_common);
1844 			if (nh->nh_tclassid &&
1845 			    nla_put_u32(skb, RTA_FLOW, nh->nh_tclassid))
1846 				goto nla_put_failure;
1847 		}
1848 #endif
1849 	} else {
1850 		if (fib_add_multipath(skb, fi) < 0)
1851 			goto nla_put_failure;
1852 	}
1853 
1854 offload:
1855 	if (fri->offload)
1856 		rtm->rtm_flags |= RTM_F_OFFLOAD;
1857 	if (fri->trap)
1858 		rtm->rtm_flags |= RTM_F_TRAP;
1859 	if (fri->offload_failed)
1860 		rtm->rtm_flags |= RTM_F_OFFLOAD_FAILED;
1861 
1862 	nlmsg_end(skb, nlh);
1863 	return 0;
1864 
1865 nla_put_failure:
1866 	nlmsg_cancel(skb, nlh);
1867 	return -EMSGSIZE;
1868 }
1869 
1870 /*
1871  * Update FIB if:
1872  * - local address disappeared -> we must delete all the entries
1873  *   referring to it.
1874  * - device went down -> we must shutdown all nexthops going via it.
1875  */
fib_sync_down_addr(struct net_device * dev,__be32 local)1876 int fib_sync_down_addr(struct net_device *dev, __be32 local)
1877 {
1878 	int tb_id = l3mdev_fib_table(dev) ? : RT_TABLE_MAIN;
1879 	struct net *net = dev_net(dev);
1880 	struct hlist_head *head;
1881 	struct fib_info *fi;
1882 	int ret = 0;
1883 
1884 	if (!fib_info_laddrhash || local == 0)
1885 		return 0;
1886 
1887 	head = fib_info_laddrhash_bucket(net, local);
1888 	hlist_for_each_entry(fi, head, fib_lhash) {
1889 		if (!net_eq(fi->fib_net, net) ||
1890 		    fi->fib_tb_id != tb_id)
1891 			continue;
1892 		if (fi->fib_prefsrc == local) {
1893 			fi->fib_flags |= RTNH_F_DEAD;
1894 			fi->pfsrc_removed = true;
1895 			ret++;
1896 		}
1897 	}
1898 	return ret;
1899 }
1900 
call_fib_nh_notifiers(struct fib_nh * nh,enum fib_event_type event_type)1901 static int call_fib_nh_notifiers(struct fib_nh *nh,
1902 				 enum fib_event_type event_type)
1903 {
1904 	bool ignore_link_down = ip_ignore_linkdown(nh->fib_nh_dev);
1905 	struct fib_nh_notifier_info info = {
1906 		.fib_nh = nh,
1907 	};
1908 
1909 	switch (event_type) {
1910 	case FIB_EVENT_NH_ADD:
1911 		if (nh->fib_nh_flags & RTNH_F_DEAD)
1912 			break;
1913 		if (ignore_link_down && nh->fib_nh_flags & RTNH_F_LINKDOWN)
1914 			break;
1915 		return call_fib4_notifiers(dev_net(nh->fib_nh_dev), event_type,
1916 					   &info.info);
1917 	case FIB_EVENT_NH_DEL:
1918 		if ((ignore_link_down && nh->fib_nh_flags & RTNH_F_LINKDOWN) ||
1919 		    (nh->fib_nh_flags & RTNH_F_DEAD))
1920 			return call_fib4_notifiers(dev_net(nh->fib_nh_dev),
1921 						   event_type, &info.info);
1922 		break;
1923 	default:
1924 		break;
1925 	}
1926 
1927 	return NOTIFY_DONE;
1928 }
1929 
1930 /* Update the PMTU of exceptions when:
1931  * - the new MTU of the first hop becomes smaller than the PMTU
1932  * - the old MTU was the same as the PMTU, and it limited discovery of
1933  *   larger MTUs on the path. With that limit raised, we can now
1934  *   discover larger MTUs
1935  * A special case is locked exceptions, for which the PMTU is smaller
1936  * than the minimal accepted PMTU:
1937  * - if the new MTU is greater than the PMTU, don't make any change
1938  * - otherwise, unlock and set PMTU
1939  */
fib_nhc_update_mtu(struct fib_nh_common * nhc,u32 new,u32 orig)1940 void fib_nhc_update_mtu(struct fib_nh_common *nhc, u32 new, u32 orig)
1941 {
1942 	struct fnhe_hash_bucket *bucket;
1943 	int i;
1944 
1945 	bucket = rcu_dereference_protected(nhc->nhc_exceptions, 1);
1946 	if (!bucket)
1947 		return;
1948 
1949 	for (i = 0; i < FNHE_HASH_SIZE; i++) {
1950 		struct fib_nh_exception *fnhe;
1951 
1952 		for (fnhe = rcu_dereference_protected(bucket[i].chain, 1);
1953 		     fnhe;
1954 		     fnhe = rcu_dereference_protected(fnhe->fnhe_next, 1)) {
1955 			if (fnhe->fnhe_mtu_locked) {
1956 				if (new <= fnhe->fnhe_pmtu) {
1957 					fnhe->fnhe_pmtu = new;
1958 					fnhe->fnhe_mtu_locked = false;
1959 				}
1960 			} else if (new < fnhe->fnhe_pmtu ||
1961 				   orig == fnhe->fnhe_pmtu) {
1962 				fnhe->fnhe_pmtu = new;
1963 			}
1964 		}
1965 	}
1966 }
1967 
fib_sync_mtu(struct net_device * dev,u32 orig_mtu)1968 void fib_sync_mtu(struct net_device *dev, u32 orig_mtu)
1969 {
1970 	struct hlist_head *head = fib_info_devhash_bucket(dev);
1971 	struct fib_nh *nh;
1972 
1973 	hlist_for_each_entry(nh, head, nh_hash) {
1974 		if (nh->fib_nh_dev == dev)
1975 			fib_nhc_update_mtu(&nh->nh_common, dev->mtu, orig_mtu);
1976 	}
1977 }
1978 
1979 /* Event              force Flags           Description
1980  * NETDEV_CHANGE      0     LINKDOWN        Carrier OFF, not for scope host
1981  * NETDEV_DOWN        0     LINKDOWN|DEAD   Link down, not for scope host
1982  * NETDEV_DOWN        1     LINKDOWN|DEAD   Last address removed
1983  * NETDEV_UNREGISTER  1     LINKDOWN|DEAD   Device removed
1984  *
1985  * only used when fib_nh is built into fib_info
1986  */
fib_sync_down_dev(struct net_device * dev,unsigned long event,bool force)1987 int fib_sync_down_dev(struct net_device *dev, unsigned long event, bool force)
1988 {
1989 	struct hlist_head *head = fib_info_devhash_bucket(dev);
1990 	struct fib_info *prev_fi = NULL;
1991 	int scope = RT_SCOPE_NOWHERE;
1992 	struct fib_nh *nh;
1993 	int ret = 0;
1994 
1995 	if (force)
1996 		scope = -1;
1997 
1998 	hlist_for_each_entry(nh, head, nh_hash) {
1999 		struct fib_info *fi = nh->nh_parent;
2000 		int dead;
2001 
2002 		BUG_ON(!fi->fib_nhs);
2003 		if (nh->fib_nh_dev != dev || fi == prev_fi)
2004 			continue;
2005 		prev_fi = fi;
2006 		dead = 0;
2007 		change_nexthops(fi) {
2008 			if (nexthop_nh->fib_nh_flags & RTNH_F_DEAD)
2009 				dead++;
2010 			else if (nexthop_nh->fib_nh_dev == dev &&
2011 				 nexthop_nh->fib_nh_scope != scope) {
2012 				switch (event) {
2013 				case NETDEV_DOWN:
2014 				case NETDEV_UNREGISTER:
2015 					nexthop_nh->fib_nh_flags |= RTNH_F_DEAD;
2016 					fallthrough;
2017 				case NETDEV_CHANGE:
2018 					nexthop_nh->fib_nh_flags |= RTNH_F_LINKDOWN;
2019 					break;
2020 				}
2021 				call_fib_nh_notifiers(nexthop_nh,
2022 						      FIB_EVENT_NH_DEL);
2023 				dead++;
2024 			}
2025 #ifdef CONFIG_IP_ROUTE_MULTIPATH
2026 			if (event == NETDEV_UNREGISTER &&
2027 			    nexthop_nh->fib_nh_dev == dev) {
2028 				dead = fi->fib_nhs;
2029 				break;
2030 			}
2031 #endif
2032 		} endfor_nexthops(fi)
2033 		if (dead == fi->fib_nhs) {
2034 			switch (event) {
2035 			case NETDEV_DOWN:
2036 			case NETDEV_UNREGISTER:
2037 				fi->fib_flags |= RTNH_F_DEAD;
2038 				fallthrough;
2039 			case NETDEV_CHANGE:
2040 				fi->fib_flags |= RTNH_F_LINKDOWN;
2041 				break;
2042 			}
2043 			ret++;
2044 		}
2045 
2046 		fib_rebalance(fi);
2047 	}
2048 
2049 	return ret;
2050 }
2051 
2052 /* Must be invoked inside of an RCU protected region.  */
fib_select_default(const struct flowi4 * flp,struct fib_result * res)2053 static void fib_select_default(const struct flowi4 *flp, struct fib_result *res)
2054 {
2055 	struct fib_info *fi = NULL, *last_resort = NULL;
2056 	struct hlist_head *fa_head = res->fa_head;
2057 	struct fib_table *tb = res->table;
2058 	u8 slen = 32 - res->prefixlen;
2059 	int order = -1, last_idx = -1;
2060 	struct fib_alias *fa, *fa1 = NULL;
2061 	u32 last_prio = res->fi->fib_priority;
2062 	dscp_t last_dscp = 0;
2063 
2064 	hlist_for_each_entry_rcu(fa, fa_head, fa_list) {
2065 		struct fib_info *next_fi = fa->fa_info;
2066 		struct fib_nh_common *nhc;
2067 
2068 		if (fa->fa_slen != slen)
2069 			continue;
2070 		if (fa->fa_dscp &&
2071 		    fa->fa_dscp != inet_dsfield_to_dscp(flp->flowi4_tos))
2072 			continue;
2073 		if (fa->tb_id != tb->tb_id)
2074 			continue;
2075 		if (next_fi->fib_priority > last_prio &&
2076 		    fa->fa_dscp == last_dscp) {
2077 			if (last_dscp)
2078 				continue;
2079 			break;
2080 		}
2081 		if (next_fi->fib_flags & RTNH_F_DEAD)
2082 			continue;
2083 		last_dscp = fa->fa_dscp;
2084 		last_prio = next_fi->fib_priority;
2085 
2086 		if (next_fi->fib_scope != res->scope ||
2087 		    fa->fa_type != RTN_UNICAST)
2088 			continue;
2089 
2090 		nhc = fib_info_nhc(next_fi, 0);
2091 		if (!nhc->nhc_gw_family || nhc->nhc_scope != RT_SCOPE_LINK)
2092 			continue;
2093 
2094 		fib_alias_accessed(fa);
2095 
2096 		if (!fi) {
2097 			if (next_fi != res->fi)
2098 				break;
2099 			fa1 = fa;
2100 		} else if (!fib_detect_death(fi, order, &last_resort,
2101 					     &last_idx, fa1->fa_default)) {
2102 			fib_result_assign(res, fi);
2103 			fa1->fa_default = order;
2104 			goto out;
2105 		}
2106 		fi = next_fi;
2107 		order++;
2108 	}
2109 
2110 	if (order <= 0 || !fi) {
2111 		if (fa1)
2112 			fa1->fa_default = -1;
2113 		goto out;
2114 	}
2115 
2116 	if (!fib_detect_death(fi, order, &last_resort, &last_idx,
2117 			      fa1->fa_default)) {
2118 		fib_result_assign(res, fi);
2119 		fa1->fa_default = order;
2120 		goto out;
2121 	}
2122 
2123 	if (last_idx >= 0)
2124 		fib_result_assign(res, last_resort);
2125 	fa1->fa_default = last_idx;
2126 out:
2127 	return;
2128 }
2129 
2130 /*
2131  * Dead device goes up. We wake up dead nexthops.
2132  * It takes sense only on multipath routes.
2133  *
2134  * only used when fib_nh is built into fib_info
2135  */
fib_sync_up(struct net_device * dev,unsigned char nh_flags)2136 int fib_sync_up(struct net_device *dev, unsigned char nh_flags)
2137 {
2138 	struct fib_info *prev_fi;
2139 	struct hlist_head *head;
2140 	struct fib_nh *nh;
2141 	int ret;
2142 
2143 	if (!(dev->flags & IFF_UP))
2144 		return 0;
2145 
2146 	if (nh_flags & RTNH_F_DEAD) {
2147 		unsigned int flags = dev_get_flags(dev);
2148 
2149 		if (flags & (IFF_RUNNING | IFF_LOWER_UP))
2150 			nh_flags |= RTNH_F_LINKDOWN;
2151 	}
2152 
2153 	prev_fi = NULL;
2154 	head = fib_info_devhash_bucket(dev);
2155 	ret = 0;
2156 
2157 	hlist_for_each_entry(nh, head, nh_hash) {
2158 		struct fib_info *fi = nh->nh_parent;
2159 		int alive;
2160 
2161 		BUG_ON(!fi->fib_nhs);
2162 		if (nh->fib_nh_dev != dev || fi == prev_fi)
2163 			continue;
2164 
2165 		prev_fi = fi;
2166 		alive = 0;
2167 		change_nexthops(fi) {
2168 			if (!(nexthop_nh->fib_nh_flags & nh_flags)) {
2169 				alive++;
2170 				continue;
2171 			}
2172 			if (!nexthop_nh->fib_nh_dev ||
2173 			    !(nexthop_nh->fib_nh_dev->flags & IFF_UP))
2174 				continue;
2175 			if (nexthop_nh->fib_nh_dev != dev ||
2176 			    !__in_dev_get_rtnl(dev))
2177 				continue;
2178 			alive++;
2179 			nexthop_nh->fib_nh_flags &= ~nh_flags;
2180 			call_fib_nh_notifiers(nexthop_nh, FIB_EVENT_NH_ADD);
2181 		} endfor_nexthops(fi)
2182 
2183 		if (alive > 0) {
2184 			fi->fib_flags &= ~nh_flags;
2185 			ret++;
2186 		}
2187 
2188 		fib_rebalance(fi);
2189 	}
2190 
2191 	return ret;
2192 }
2193 
2194 #ifdef CONFIG_IP_ROUTE_MULTIPATH
fib_good_nh(const struct fib_nh * nh)2195 static bool fib_good_nh(const struct fib_nh *nh)
2196 {
2197 	int state = NUD_REACHABLE;
2198 
2199 	if (nh->fib_nh_scope == RT_SCOPE_LINK) {
2200 		struct neighbour *n;
2201 
2202 		rcu_read_lock();
2203 
2204 		if (likely(nh->fib_nh_gw_family == AF_INET))
2205 			n = __ipv4_neigh_lookup_noref(nh->fib_nh_dev,
2206 						   (__force u32)nh->fib_nh_gw4);
2207 		else if (nh->fib_nh_gw_family == AF_INET6)
2208 			n = __ipv6_neigh_lookup_noref_stub(nh->fib_nh_dev,
2209 							   &nh->fib_nh_gw6);
2210 		else
2211 			n = NULL;
2212 		if (n)
2213 			state = READ_ONCE(n->nud_state);
2214 
2215 		rcu_read_unlock();
2216 	}
2217 
2218 	return !!(state & NUD_VALID);
2219 }
2220 
fib_select_multipath(struct fib_result * res,int hash)2221 void fib_select_multipath(struct fib_result *res, int hash)
2222 {
2223 	struct fib_info *fi = res->fi;
2224 	struct net *net = fi->fib_net;
2225 	bool first = false;
2226 
2227 	if (unlikely(res->fi->nh)) {
2228 		nexthop_path_fib_result(res, hash);
2229 		return;
2230 	}
2231 
2232 	change_nexthops(fi) {
2233 		if (READ_ONCE(net->ipv4.sysctl_fib_multipath_use_neigh)) {
2234 			if (!fib_good_nh(nexthop_nh))
2235 				continue;
2236 			if (!first) {
2237 				res->nh_sel = nhsel;
2238 				res->nhc = &nexthop_nh->nh_common;
2239 				first = true;
2240 			}
2241 		}
2242 
2243 		if (hash > atomic_read(&nexthop_nh->fib_nh_upper_bound))
2244 			continue;
2245 
2246 		res->nh_sel = nhsel;
2247 		res->nhc = &nexthop_nh->nh_common;
2248 		return;
2249 	} endfor_nexthops(fi);
2250 }
2251 #endif
2252 
fib_select_path(struct net * net,struct fib_result * res,struct flowi4 * fl4,const struct sk_buff * skb)2253 void fib_select_path(struct net *net, struct fib_result *res,
2254 		     struct flowi4 *fl4, const struct sk_buff *skb)
2255 {
2256 	if (fl4->flowi4_oif)
2257 		goto check_saddr;
2258 
2259 #ifdef CONFIG_IP_ROUTE_MULTIPATH
2260 	if (fib_info_num_path(res->fi) > 1) {
2261 		int h = fib_multipath_hash(net, fl4, skb, NULL);
2262 
2263 		fib_select_multipath(res, h);
2264 	}
2265 	else
2266 #endif
2267 	if (!res->prefixlen &&
2268 	    res->table->tb_num_default > 1 &&
2269 	    res->type == RTN_UNICAST)
2270 		fib_select_default(fl4, res);
2271 
2272 check_saddr:
2273 	if (!fl4->saddr)
2274 		fl4->saddr = fib_result_prefsrc(net, res);
2275 }
2276