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