xref: /linux/net/ipv4/fib_frontend.c (revision 3fd6c59042dbba50391e30862beac979491145fe)
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: FIB frontend.
8  *
9  * Authors:	Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
10  */
11 
12 #include <linux/module.h>
13 #include <linux/uaccess.h>
14 #include <linux/bitops.h>
15 #include <linux/capability.h>
16 #include <linux/types.h>
17 #include <linux/kernel.h>
18 #include <linux/mm.h>
19 #include <linux/string.h>
20 #include <linux/socket.h>
21 #include <linux/sockios.h>
22 #include <linux/errno.h>
23 #include <linux/in.h>
24 #include <linux/inet.h>
25 #include <linux/inetdevice.h>
26 #include <linux/netdevice.h>
27 #include <linux/if_addr.h>
28 #include <linux/if_arp.h>
29 #include <linux/skbuff.h>
30 #include <linux/cache.h>
31 #include <linux/init.h>
32 #include <linux/list.h>
33 #include <linux/slab.h>
34 
35 #include <net/inet_dscp.h>
36 #include <net/ip.h>
37 #include <net/protocol.h>
38 #include <net/route.h>
39 #include <net/tcp.h>
40 #include <net/sock.h>
41 #include <net/arp.h>
42 #include <net/ip_fib.h>
43 #include <net/nexthop.h>
44 #include <net/rtnetlink.h>
45 #include <net/xfrm.h>
46 #include <net/l3mdev.h>
47 #include <net/lwtunnel.h>
48 #include <trace/events/fib.h>
49 
50 #ifndef CONFIG_IP_MULTIPLE_TABLES
51 
fib4_rules_init(struct net * net)52 static int __net_init fib4_rules_init(struct net *net)
53 {
54 	struct fib_table *local_table, *main_table;
55 
56 	main_table  = fib_trie_table(RT_TABLE_MAIN, NULL);
57 	if (!main_table)
58 		return -ENOMEM;
59 
60 	local_table = fib_trie_table(RT_TABLE_LOCAL, main_table);
61 	if (!local_table)
62 		goto fail;
63 
64 	hlist_add_head_rcu(&local_table->tb_hlist,
65 				&net->ipv4.fib_table_hash[TABLE_LOCAL_INDEX]);
66 	hlist_add_head_rcu(&main_table->tb_hlist,
67 				&net->ipv4.fib_table_hash[TABLE_MAIN_INDEX]);
68 	return 0;
69 
70 fail:
71 	fib_free_table(main_table);
72 	return -ENOMEM;
73 }
74 #else
75 
fib_new_table(struct net * net,u32 id)76 struct fib_table *fib_new_table(struct net *net, u32 id)
77 {
78 	struct fib_table *tb, *alias = NULL;
79 	unsigned int h;
80 
81 	if (id == 0)
82 		id = RT_TABLE_MAIN;
83 	tb = fib_get_table(net, id);
84 	if (tb)
85 		return tb;
86 
87 	if (id == RT_TABLE_LOCAL && !net->ipv4.fib_has_custom_rules)
88 		alias = fib_new_table(net, RT_TABLE_MAIN);
89 
90 	tb = fib_trie_table(id, alias);
91 	if (!tb)
92 		return NULL;
93 
94 	switch (id) {
95 	case RT_TABLE_MAIN:
96 		rcu_assign_pointer(net->ipv4.fib_main, tb);
97 		break;
98 	case RT_TABLE_DEFAULT:
99 		rcu_assign_pointer(net->ipv4.fib_default, tb);
100 		break;
101 	default:
102 		break;
103 	}
104 
105 	h = id & (FIB_TABLE_HASHSZ - 1);
106 	hlist_add_head_rcu(&tb->tb_hlist, &net->ipv4.fib_table_hash[h]);
107 	return tb;
108 }
109 EXPORT_SYMBOL_GPL(fib_new_table);
110 
111 /* caller must hold either rtnl or rcu read lock */
fib_get_table(struct net * net,u32 id)112 struct fib_table *fib_get_table(struct net *net, u32 id)
113 {
114 	struct fib_table *tb;
115 	struct hlist_head *head;
116 	unsigned int h;
117 
118 	if (id == 0)
119 		id = RT_TABLE_MAIN;
120 	h = id & (FIB_TABLE_HASHSZ - 1);
121 
122 	head = &net->ipv4.fib_table_hash[h];
123 	hlist_for_each_entry_rcu(tb, head, tb_hlist,
124 				 lockdep_rtnl_is_held()) {
125 		if (tb->tb_id == id)
126 			return tb;
127 	}
128 	return NULL;
129 }
130 #endif /* CONFIG_IP_MULTIPLE_TABLES */
131 
fib_replace_table(struct net * net,struct fib_table * old,struct fib_table * new)132 static void fib_replace_table(struct net *net, struct fib_table *old,
133 			      struct fib_table *new)
134 {
135 #ifdef CONFIG_IP_MULTIPLE_TABLES
136 	switch (new->tb_id) {
137 	case RT_TABLE_MAIN:
138 		rcu_assign_pointer(net->ipv4.fib_main, new);
139 		break;
140 	case RT_TABLE_DEFAULT:
141 		rcu_assign_pointer(net->ipv4.fib_default, new);
142 		break;
143 	default:
144 		break;
145 	}
146 
147 #endif
148 	/* replace the old table in the hlist */
149 	hlist_replace_rcu(&old->tb_hlist, &new->tb_hlist);
150 }
151 
fib_unmerge(struct net * net)152 int fib_unmerge(struct net *net)
153 {
154 	struct fib_table *old, *new, *main_table;
155 
156 	/* attempt to fetch local table if it has been allocated */
157 	old = fib_get_table(net, RT_TABLE_LOCAL);
158 	if (!old)
159 		return 0;
160 
161 	new = fib_trie_unmerge(old);
162 	if (!new)
163 		return -ENOMEM;
164 
165 	/* table is already unmerged */
166 	if (new == old)
167 		return 0;
168 
169 	/* replace merged table with clean table */
170 	fib_replace_table(net, old, new);
171 	fib_free_table(old);
172 
173 	/* attempt to fetch main table if it has been allocated */
174 	main_table = fib_get_table(net, RT_TABLE_MAIN);
175 	if (!main_table)
176 		return 0;
177 
178 	/* flush local entries from main table */
179 	fib_table_flush_external(main_table);
180 
181 	return 0;
182 }
183 
fib_flush(struct net * net)184 void fib_flush(struct net *net)
185 {
186 	int flushed = 0;
187 	unsigned int h;
188 
189 	for (h = 0; h < FIB_TABLE_HASHSZ; h++) {
190 		struct hlist_head *head = &net->ipv4.fib_table_hash[h];
191 		struct hlist_node *tmp;
192 		struct fib_table *tb;
193 
194 		hlist_for_each_entry_safe(tb, tmp, head, tb_hlist)
195 			flushed += fib_table_flush(net, tb, false);
196 	}
197 
198 	if (flushed)
199 		rt_cache_flush(net);
200 }
201 
202 /*
203  * Find address type as if only "dev" was present in the system. If
204  * on_dev is NULL then all interfaces are taken into consideration.
205  */
__inet_dev_addr_type(struct net * net,const struct net_device * dev,__be32 addr,u32 tb_id)206 static inline unsigned int __inet_dev_addr_type(struct net *net,
207 						const struct net_device *dev,
208 						__be32 addr, u32 tb_id)
209 {
210 	struct flowi4		fl4 = { .daddr = addr };
211 	struct fib_result	res;
212 	unsigned int ret = RTN_BROADCAST;
213 	struct fib_table *table;
214 
215 	if (ipv4_is_zeronet(addr) || ipv4_is_lbcast(addr))
216 		return RTN_BROADCAST;
217 	if (ipv4_is_multicast(addr))
218 		return RTN_MULTICAST;
219 
220 	rcu_read_lock();
221 
222 	table = fib_get_table(net, tb_id);
223 	if (table) {
224 		ret = RTN_UNICAST;
225 		if (!fib_table_lookup(table, &fl4, &res, FIB_LOOKUP_NOREF)) {
226 			struct fib_nh_common *nhc = fib_info_nhc(res.fi, 0);
227 
228 			if (!dev || dev == nhc->nhc_dev)
229 				ret = res.type;
230 		}
231 	}
232 
233 	rcu_read_unlock();
234 	return ret;
235 }
236 
inet_addr_type_table(struct net * net,__be32 addr,u32 tb_id)237 unsigned int inet_addr_type_table(struct net *net, __be32 addr, u32 tb_id)
238 {
239 	return __inet_dev_addr_type(net, NULL, addr, tb_id);
240 }
241 EXPORT_SYMBOL(inet_addr_type_table);
242 
inet_addr_type(struct net * net,__be32 addr)243 unsigned int inet_addr_type(struct net *net, __be32 addr)
244 {
245 	return __inet_dev_addr_type(net, NULL, addr, RT_TABLE_LOCAL);
246 }
247 EXPORT_SYMBOL(inet_addr_type);
248 
inet_dev_addr_type(struct net * net,const struct net_device * dev,__be32 addr)249 unsigned int inet_dev_addr_type(struct net *net, const struct net_device *dev,
250 				__be32 addr)
251 {
252 	u32 rt_table = l3mdev_fib_table(dev) ? : RT_TABLE_LOCAL;
253 
254 	return __inet_dev_addr_type(net, dev, addr, rt_table);
255 }
256 EXPORT_SYMBOL(inet_dev_addr_type);
257 
258 /* inet_addr_type with dev == NULL but using the table from a dev
259  * if one is associated
260  */
inet_addr_type_dev_table(struct net * net,const struct net_device * dev,__be32 addr)261 unsigned int inet_addr_type_dev_table(struct net *net,
262 				      const struct net_device *dev,
263 				      __be32 addr)
264 {
265 	u32 rt_table = l3mdev_fib_table(dev) ? : RT_TABLE_LOCAL;
266 
267 	return __inet_dev_addr_type(net, NULL, addr, rt_table);
268 }
269 EXPORT_SYMBOL(inet_addr_type_dev_table);
270 
fib_compute_spec_dst(struct sk_buff * skb)271 __be32 fib_compute_spec_dst(struct sk_buff *skb)
272 {
273 	struct net_device *dev = skb->dev;
274 	struct in_device *in_dev;
275 	struct fib_result res;
276 	struct rtable *rt;
277 	struct net *net;
278 	int scope;
279 
280 	rt = skb_rtable(skb);
281 	if ((rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST | RTCF_LOCAL)) ==
282 	    RTCF_LOCAL)
283 		return ip_hdr(skb)->daddr;
284 
285 	in_dev = __in_dev_get_rcu(dev);
286 
287 	net = dev_net(dev);
288 
289 	scope = RT_SCOPE_UNIVERSE;
290 	if (!ipv4_is_zeronet(ip_hdr(skb)->saddr)) {
291 		bool vmark = in_dev && IN_DEV_SRC_VMARK(in_dev);
292 		struct flowi4 fl4 = {
293 			.flowi4_iif = LOOPBACK_IFINDEX,
294 			.flowi4_l3mdev = l3mdev_master_ifindex_rcu(dev),
295 			.daddr = ip_hdr(skb)->saddr,
296 			.flowi4_tos = inet_dscp_to_dsfield(ip4h_dscp(ip_hdr(skb))),
297 			.flowi4_scope = scope,
298 			.flowi4_mark = vmark ? skb->mark : 0,
299 		};
300 		if (!fib_lookup(net, &fl4, &res, 0))
301 			return fib_result_prefsrc(net, &res);
302 	} else {
303 		scope = RT_SCOPE_LINK;
304 	}
305 
306 	return inet_select_addr(dev, ip_hdr(skb)->saddr, scope);
307 }
308 
fib_info_nh_uses_dev(struct fib_info * fi,const struct net_device * dev)309 bool fib_info_nh_uses_dev(struct fib_info *fi, const struct net_device *dev)
310 {
311 	bool dev_match = false;
312 #ifdef CONFIG_IP_ROUTE_MULTIPATH
313 	if (unlikely(fi->nh)) {
314 		dev_match = nexthop_uses_dev(fi->nh, dev);
315 	} else {
316 		int ret;
317 
318 		for (ret = 0; ret < fib_info_num_path(fi); ret++) {
319 			const struct fib_nh_common *nhc = fib_info_nhc(fi, ret);
320 
321 			if (nhc_l3mdev_matches_dev(nhc, dev)) {
322 				dev_match = true;
323 				break;
324 			}
325 		}
326 	}
327 #else
328 	if (fib_info_nhc(fi, 0)->nhc_dev == dev)
329 		dev_match = true;
330 #endif
331 
332 	return dev_match;
333 }
334 EXPORT_SYMBOL_GPL(fib_info_nh_uses_dev);
335 
336 /* Given (packet source, input interface) and optional (dst, oif, tos):
337  * - (main) check, that source is valid i.e. not broadcast or our local
338  *   address.
339  * - figure out what "logical" interface this packet arrived
340  *   and calculate "specific destination" address.
341  * - check, that packet arrived from expected physical interface.
342  * called with rcu_read_lock()
343  */
__fib_validate_source(struct sk_buff * skb,__be32 src,__be32 dst,dscp_t dscp,int oif,struct net_device * dev,int rpf,struct in_device * idev,u32 * itag)344 static int __fib_validate_source(struct sk_buff *skb, __be32 src, __be32 dst,
345 				 dscp_t dscp, int oif, struct net_device *dev,
346 				 int rpf, struct in_device *idev, u32 *itag)
347 {
348 	struct net *net = dev_net(dev);
349 	enum skb_drop_reason reason;
350 	struct flow_keys flkeys;
351 	int ret, no_addr;
352 	struct fib_result res;
353 	struct flowi4 fl4;
354 	bool dev_match;
355 
356 	fl4.flowi4_oif = 0;
357 	fl4.flowi4_l3mdev = l3mdev_master_ifindex_rcu(dev);
358 	fl4.flowi4_iif = oif ? : LOOPBACK_IFINDEX;
359 	fl4.daddr = src;
360 	fl4.saddr = dst;
361 	fl4.flowi4_tos = inet_dscp_to_dsfield(dscp);
362 	fl4.flowi4_scope = RT_SCOPE_UNIVERSE;
363 	fl4.flowi4_tun_key.tun_id = 0;
364 	fl4.flowi4_flags = 0;
365 	fl4.flowi4_uid = sock_net_uid(net, NULL);
366 	fl4.flowi4_multipath_hash = 0;
367 
368 	no_addr = idev->ifa_list == NULL;
369 
370 	fl4.flowi4_mark = IN_DEV_SRC_VMARK(idev) ? skb->mark : 0;
371 	if (!fib4_rules_early_flow_dissect(net, skb, &fl4, &flkeys)) {
372 		fl4.flowi4_proto = 0;
373 		fl4.fl4_sport = 0;
374 		fl4.fl4_dport = 0;
375 	} else {
376 		swap(fl4.fl4_sport, fl4.fl4_dport);
377 	}
378 
379 	if (fib_lookup(net, &fl4, &res, 0))
380 		goto last_resort;
381 	if (res.type != RTN_UNICAST) {
382 		if (res.type != RTN_LOCAL) {
383 			reason = SKB_DROP_REASON_IP_INVALID_SOURCE;
384 			goto e_inval;
385 		} else if (!IN_DEV_ACCEPT_LOCAL(idev)) {
386 			reason = SKB_DROP_REASON_IP_LOCAL_SOURCE;
387 			goto e_inval;
388 		}
389 	}
390 	fib_combine_itag(itag, &res);
391 
392 	dev_match = fib_info_nh_uses_dev(res.fi, dev);
393 	/* This is not common, loopback packets retain skb_dst so normally they
394 	 * would not even hit this slow path.
395 	 */
396 	dev_match = dev_match || (res.type == RTN_LOCAL &&
397 				  dev == net->loopback_dev);
398 	if (dev_match) {
399 		ret = FIB_RES_NHC(res)->nhc_scope >= RT_SCOPE_HOST;
400 		return ret;
401 	}
402 	if (no_addr)
403 		goto last_resort;
404 	if (rpf == 1)
405 		goto e_rpf;
406 	fl4.flowi4_oif = dev->ifindex;
407 
408 	ret = 0;
409 	if (fib_lookup(net, &fl4, &res, FIB_LOOKUP_IGNORE_LINKSTATE) == 0) {
410 		if (res.type == RTN_UNICAST)
411 			ret = FIB_RES_NHC(res)->nhc_scope >= RT_SCOPE_HOST;
412 	}
413 	return ret;
414 
415 last_resort:
416 	if (rpf)
417 		goto e_rpf;
418 	*itag = 0;
419 	return 0;
420 
421 e_inval:
422 	return -reason;
423 e_rpf:
424 	return -SKB_DROP_REASON_IP_RPFILTER;
425 }
426 
427 /* Ignore rp_filter for packets protected by IPsec. */
fib_validate_source(struct sk_buff * skb,__be32 src,__be32 dst,dscp_t dscp,int oif,struct net_device * dev,struct in_device * idev,u32 * itag)428 int fib_validate_source(struct sk_buff *skb, __be32 src, __be32 dst,
429 			dscp_t dscp, int oif, struct net_device *dev,
430 			struct in_device *idev, u32 *itag)
431 {
432 	int r = secpath_exists(skb) ? 0 : IN_DEV_RPFILTER(idev);
433 	struct net *net = dev_net(dev);
434 
435 	if (!r && !fib_num_tclassid_users(net) &&
436 	    (dev->ifindex != oif || !IN_DEV_TX_REDIRECTS(idev))) {
437 		if (IN_DEV_ACCEPT_LOCAL(idev))
438 			goto ok;
439 		/* with custom local routes in place, checking local addresses
440 		 * only will be too optimistic, with custom rules, checking
441 		 * local addresses only can be too strict, e.g. due to vrf
442 		 */
443 		if (net->ipv4.fib_has_custom_local_routes ||
444 		    fib4_has_custom_rules(net))
445 			goto full_check;
446 		/* Within the same container, it is regarded as a martian source,
447 		 * and the same host but different containers are not.
448 		 */
449 		if (inet_lookup_ifaddr_rcu(net, src))
450 			return -SKB_DROP_REASON_IP_LOCAL_SOURCE;
451 
452 ok:
453 		*itag = 0;
454 		return 0;
455 	}
456 
457 full_check:
458 	return __fib_validate_source(skb, src, dst, dscp, oif, dev, r, idev,
459 				     itag);
460 }
461 
sk_extract_addr(struct sockaddr * addr)462 static inline __be32 sk_extract_addr(struct sockaddr *addr)
463 {
464 	return ((struct sockaddr_in *) addr)->sin_addr.s_addr;
465 }
466 
put_rtax(struct nlattr * mx,int len,int type,u32 value)467 static int put_rtax(struct nlattr *mx, int len, int type, u32 value)
468 {
469 	struct nlattr *nla;
470 
471 	nla = (struct nlattr *) ((char *) mx + len);
472 	nla->nla_type = type;
473 	nla->nla_len = nla_attr_size(4);
474 	*(u32 *) nla_data(nla) = value;
475 
476 	return len + nla_total_size(4);
477 }
478 
rtentry_to_fib_config(struct net * net,int cmd,struct rtentry * rt,struct fib_config * cfg)479 static int rtentry_to_fib_config(struct net *net, int cmd, struct rtentry *rt,
480 				 struct fib_config *cfg)
481 {
482 	__be32 addr;
483 	int plen;
484 
485 	memset(cfg, 0, sizeof(*cfg));
486 	cfg->fc_nlinfo.nl_net = net;
487 
488 	if (rt->rt_dst.sa_family != AF_INET)
489 		return -EAFNOSUPPORT;
490 
491 	/*
492 	 * Check mask for validity:
493 	 * a) it must be contiguous.
494 	 * b) destination must have all host bits clear.
495 	 * c) if application forgot to set correct family (AF_INET),
496 	 *    reject request unless it is absolutely clear i.e.
497 	 *    both family and mask are zero.
498 	 */
499 	plen = 32;
500 	addr = sk_extract_addr(&rt->rt_dst);
501 	if (!(rt->rt_flags & RTF_HOST)) {
502 		__be32 mask = sk_extract_addr(&rt->rt_genmask);
503 
504 		if (rt->rt_genmask.sa_family != AF_INET) {
505 			if (mask || rt->rt_genmask.sa_family)
506 				return -EAFNOSUPPORT;
507 		}
508 
509 		if (bad_mask(mask, addr))
510 			return -EINVAL;
511 
512 		plen = inet_mask_len(mask);
513 	}
514 
515 	cfg->fc_dst_len = plen;
516 	cfg->fc_dst = addr;
517 
518 	if (cmd != SIOCDELRT) {
519 		cfg->fc_nlflags = NLM_F_CREATE;
520 		cfg->fc_protocol = RTPROT_BOOT;
521 	}
522 
523 	if (rt->rt_metric)
524 		cfg->fc_priority = rt->rt_metric - 1;
525 
526 	if (rt->rt_flags & RTF_REJECT) {
527 		cfg->fc_scope = RT_SCOPE_HOST;
528 		cfg->fc_type = RTN_UNREACHABLE;
529 		return 0;
530 	}
531 
532 	cfg->fc_scope = RT_SCOPE_NOWHERE;
533 	cfg->fc_type = RTN_UNICAST;
534 
535 	if (rt->rt_dev) {
536 		char *colon;
537 		struct net_device *dev;
538 		char devname[IFNAMSIZ];
539 
540 		if (copy_from_user(devname, rt->rt_dev, IFNAMSIZ-1))
541 			return -EFAULT;
542 
543 		devname[IFNAMSIZ-1] = 0;
544 		colon = strchr(devname, ':');
545 		if (colon)
546 			*colon = 0;
547 		dev = __dev_get_by_name(net, devname);
548 		if (!dev)
549 			return -ENODEV;
550 		cfg->fc_oif = dev->ifindex;
551 		cfg->fc_table = l3mdev_fib_table(dev);
552 		if (colon) {
553 			const struct in_ifaddr *ifa;
554 			struct in_device *in_dev;
555 
556 			in_dev = __in_dev_get_rtnl(dev);
557 			if (!in_dev)
558 				return -ENODEV;
559 
560 			*colon = ':';
561 
562 			rcu_read_lock();
563 			in_dev_for_each_ifa_rcu(ifa, in_dev) {
564 				if (strcmp(ifa->ifa_label, devname) == 0)
565 					break;
566 			}
567 			rcu_read_unlock();
568 
569 			if (!ifa)
570 				return -ENODEV;
571 			cfg->fc_prefsrc = ifa->ifa_local;
572 		}
573 	}
574 
575 	addr = sk_extract_addr(&rt->rt_gateway);
576 	if (rt->rt_gateway.sa_family == AF_INET && addr) {
577 		unsigned int addr_type;
578 
579 		cfg->fc_gw4 = addr;
580 		cfg->fc_gw_family = AF_INET;
581 		addr_type = inet_addr_type_table(net, addr, cfg->fc_table);
582 		if (rt->rt_flags & RTF_GATEWAY &&
583 		    addr_type == RTN_UNICAST)
584 			cfg->fc_scope = RT_SCOPE_UNIVERSE;
585 	}
586 
587 	if (!cfg->fc_table)
588 		cfg->fc_table = RT_TABLE_MAIN;
589 
590 	if (cmd == SIOCDELRT)
591 		return 0;
592 
593 	if (rt->rt_flags & RTF_GATEWAY && !cfg->fc_gw_family)
594 		return -EINVAL;
595 
596 	if (cfg->fc_scope == RT_SCOPE_NOWHERE)
597 		cfg->fc_scope = RT_SCOPE_LINK;
598 
599 	if (rt->rt_flags & (RTF_MTU | RTF_WINDOW | RTF_IRTT)) {
600 		struct nlattr *mx;
601 		int len = 0;
602 
603 		mx = kcalloc(3, nla_total_size(4), GFP_KERNEL);
604 		if (!mx)
605 			return -ENOMEM;
606 
607 		if (rt->rt_flags & RTF_MTU)
608 			len = put_rtax(mx, len, RTAX_ADVMSS, rt->rt_mtu - 40);
609 
610 		if (rt->rt_flags & RTF_WINDOW)
611 			len = put_rtax(mx, len, RTAX_WINDOW, rt->rt_window);
612 
613 		if (rt->rt_flags & RTF_IRTT)
614 			len = put_rtax(mx, len, RTAX_RTT, rt->rt_irtt << 3);
615 
616 		cfg->fc_mx = mx;
617 		cfg->fc_mx_len = len;
618 	}
619 
620 	return 0;
621 }
622 
623 /*
624  * Handle IP routing ioctl calls.
625  * These are used to manipulate the routing tables
626  */
ip_rt_ioctl(struct net * net,unsigned int cmd,struct rtentry * rt)627 int ip_rt_ioctl(struct net *net, unsigned int cmd, struct rtentry *rt)
628 {
629 	struct fib_config cfg;
630 	int err;
631 
632 	switch (cmd) {
633 	case SIOCADDRT:		/* Add a route */
634 	case SIOCDELRT:		/* Delete a route */
635 		if (!ns_capable(net->user_ns, CAP_NET_ADMIN))
636 			return -EPERM;
637 
638 		rtnl_lock();
639 		err = rtentry_to_fib_config(net, cmd, rt, &cfg);
640 		if (err == 0) {
641 			struct fib_table *tb;
642 
643 			if (cmd == SIOCDELRT) {
644 				tb = fib_get_table(net, cfg.fc_table);
645 				if (tb)
646 					err = fib_table_delete(net, tb, &cfg,
647 							       NULL);
648 				else
649 					err = -ESRCH;
650 			} else {
651 				tb = fib_new_table(net, cfg.fc_table);
652 				if (tb)
653 					err = fib_table_insert(net, tb,
654 							       &cfg, NULL);
655 				else
656 					err = -ENOBUFS;
657 			}
658 
659 			/* allocated by rtentry_to_fib_config() */
660 			kfree(cfg.fc_mx);
661 		}
662 		rtnl_unlock();
663 		return err;
664 	}
665 	return -EINVAL;
666 }
667 
668 const struct nla_policy rtm_ipv4_policy[RTA_MAX + 1] = {
669 	[RTA_UNSPEC]		= { .strict_start_type = RTA_DPORT + 1 },
670 	[RTA_DST]		= { .type = NLA_U32 },
671 	[RTA_SRC]		= { .type = NLA_U32 },
672 	[RTA_IIF]		= { .type = NLA_U32 },
673 	[RTA_OIF]		= { .type = NLA_U32 },
674 	[RTA_GATEWAY]		= { .type = NLA_U32 },
675 	[RTA_PRIORITY]		= { .type = NLA_U32 },
676 	[RTA_PREFSRC]		= { .type = NLA_U32 },
677 	[RTA_METRICS]		= { .type = NLA_NESTED },
678 	[RTA_MULTIPATH]		= { .len = sizeof(struct rtnexthop) },
679 	[RTA_FLOW]		= { .type = NLA_U32 },
680 	[RTA_ENCAP_TYPE]	= { .type = NLA_U16 },
681 	[RTA_ENCAP]		= { .type = NLA_NESTED },
682 	[RTA_UID]		= { .type = NLA_U32 },
683 	[RTA_MARK]		= { .type = NLA_U32 },
684 	[RTA_TABLE]		= { .type = NLA_U32 },
685 	[RTA_IP_PROTO]		= { .type = NLA_U8 },
686 	[RTA_SPORT]		= { .type = NLA_U16 },
687 	[RTA_DPORT]		= { .type = NLA_U16 },
688 	[RTA_NH_ID]		= { .type = NLA_U32 },
689 };
690 
fib_gw_from_via(struct fib_config * cfg,struct nlattr * nla,struct netlink_ext_ack * extack)691 int fib_gw_from_via(struct fib_config *cfg, struct nlattr *nla,
692 		    struct netlink_ext_ack *extack)
693 {
694 	struct rtvia *via;
695 	int alen;
696 
697 	if (nla_len(nla) < offsetof(struct rtvia, rtvia_addr)) {
698 		NL_SET_ERR_MSG(extack, "Invalid attribute length for RTA_VIA");
699 		return -EINVAL;
700 	}
701 
702 	via = nla_data(nla);
703 	alen = nla_len(nla) - offsetof(struct rtvia, rtvia_addr);
704 
705 	switch (via->rtvia_family) {
706 	case AF_INET:
707 		if (alen != sizeof(__be32)) {
708 			NL_SET_ERR_MSG(extack, "Invalid IPv4 address in RTA_VIA");
709 			return -EINVAL;
710 		}
711 		cfg->fc_gw_family = AF_INET;
712 		cfg->fc_gw4 = *((__be32 *)via->rtvia_addr);
713 		break;
714 	case AF_INET6:
715 #if IS_ENABLED(CONFIG_IPV6)
716 		if (alen != sizeof(struct in6_addr)) {
717 			NL_SET_ERR_MSG(extack, "Invalid IPv6 address in RTA_VIA");
718 			return -EINVAL;
719 		}
720 		cfg->fc_gw_family = AF_INET6;
721 		cfg->fc_gw6 = *((struct in6_addr *)via->rtvia_addr);
722 #else
723 		NL_SET_ERR_MSG(extack, "IPv6 support not enabled in kernel");
724 		return -EINVAL;
725 #endif
726 		break;
727 	default:
728 		NL_SET_ERR_MSG(extack, "Unsupported address family in RTA_VIA");
729 		return -EINVAL;
730 	}
731 
732 	return 0;
733 }
734 
rtm_to_fib_config(struct net * net,struct sk_buff * skb,struct nlmsghdr * nlh,struct fib_config * cfg,struct netlink_ext_ack * extack)735 static int rtm_to_fib_config(struct net *net, struct sk_buff *skb,
736 			     struct nlmsghdr *nlh, struct fib_config *cfg,
737 			     struct netlink_ext_ack *extack)
738 {
739 	bool has_gw = false, has_via = false;
740 	struct nlattr *attr;
741 	int err, remaining;
742 	struct rtmsg *rtm;
743 
744 	err = nlmsg_validate_deprecated(nlh, sizeof(*rtm), RTA_MAX,
745 					rtm_ipv4_policy, extack);
746 	if (err < 0)
747 		goto errout;
748 
749 	memset(cfg, 0, sizeof(*cfg));
750 
751 	rtm = nlmsg_data(nlh);
752 
753 	if (!inet_validate_dscp(rtm->rtm_tos)) {
754 		NL_SET_ERR_MSG(extack,
755 			       "Invalid dsfield (tos): ECN bits must be 0");
756 		err = -EINVAL;
757 		goto errout;
758 	}
759 	cfg->fc_dscp = inet_dsfield_to_dscp(rtm->rtm_tos);
760 
761 	cfg->fc_dst_len = rtm->rtm_dst_len;
762 	cfg->fc_table = rtm->rtm_table;
763 	cfg->fc_protocol = rtm->rtm_protocol;
764 	cfg->fc_scope = rtm->rtm_scope;
765 	cfg->fc_type = rtm->rtm_type;
766 	cfg->fc_flags = rtm->rtm_flags;
767 	cfg->fc_nlflags = nlh->nlmsg_flags;
768 
769 	cfg->fc_nlinfo.portid = NETLINK_CB(skb).portid;
770 	cfg->fc_nlinfo.nlh = nlh;
771 	cfg->fc_nlinfo.nl_net = net;
772 
773 	if (cfg->fc_type > RTN_MAX) {
774 		NL_SET_ERR_MSG(extack, "Invalid route type");
775 		err = -EINVAL;
776 		goto errout;
777 	}
778 
779 	nlmsg_for_each_attr(attr, nlh, sizeof(struct rtmsg), remaining) {
780 		switch (nla_type(attr)) {
781 		case RTA_DST:
782 			cfg->fc_dst = nla_get_be32(attr);
783 			break;
784 		case RTA_OIF:
785 			cfg->fc_oif = nla_get_u32(attr);
786 			break;
787 		case RTA_GATEWAY:
788 			has_gw = true;
789 			cfg->fc_gw4 = nla_get_be32(attr);
790 			if (cfg->fc_gw4)
791 				cfg->fc_gw_family = AF_INET;
792 			break;
793 		case RTA_VIA:
794 			has_via = true;
795 			err = fib_gw_from_via(cfg, attr, extack);
796 			if (err)
797 				goto errout;
798 			break;
799 		case RTA_PRIORITY:
800 			cfg->fc_priority = nla_get_u32(attr);
801 			break;
802 		case RTA_PREFSRC:
803 			cfg->fc_prefsrc = nla_get_be32(attr);
804 			break;
805 		case RTA_METRICS:
806 			cfg->fc_mx = nla_data(attr);
807 			cfg->fc_mx_len = nla_len(attr);
808 			break;
809 		case RTA_MULTIPATH:
810 			err = lwtunnel_valid_encap_type_attr(nla_data(attr),
811 							     nla_len(attr),
812 							     extack);
813 			if (err < 0)
814 				goto errout;
815 			cfg->fc_mp = nla_data(attr);
816 			cfg->fc_mp_len = nla_len(attr);
817 			break;
818 		case RTA_FLOW:
819 			cfg->fc_flow = nla_get_u32(attr);
820 			break;
821 		case RTA_TABLE:
822 			cfg->fc_table = nla_get_u32(attr);
823 			break;
824 		case RTA_ENCAP:
825 			cfg->fc_encap = attr;
826 			break;
827 		case RTA_ENCAP_TYPE:
828 			cfg->fc_encap_type = nla_get_u16(attr);
829 			err = lwtunnel_valid_encap_type(cfg->fc_encap_type,
830 							extack);
831 			if (err < 0)
832 				goto errout;
833 			break;
834 		case RTA_NH_ID:
835 			cfg->fc_nh_id = nla_get_u32(attr);
836 			break;
837 		}
838 	}
839 
840 	if (cfg->fc_nh_id) {
841 		if (cfg->fc_oif || cfg->fc_gw_family ||
842 		    cfg->fc_encap || cfg->fc_mp) {
843 			NL_SET_ERR_MSG(extack,
844 				       "Nexthop specification and nexthop id are mutually exclusive");
845 			return -EINVAL;
846 		}
847 	}
848 
849 	if (has_gw && has_via) {
850 		NL_SET_ERR_MSG(extack,
851 			       "Nexthop configuration can not contain both GATEWAY and VIA");
852 		return -EINVAL;
853 	}
854 
855 	if (!cfg->fc_table)
856 		cfg->fc_table = RT_TABLE_MAIN;
857 
858 	return 0;
859 errout:
860 	return err;
861 }
862 
inet_rtm_delroute(struct sk_buff * skb,struct nlmsghdr * nlh,struct netlink_ext_ack * extack)863 static int inet_rtm_delroute(struct sk_buff *skb, struct nlmsghdr *nlh,
864 			     struct netlink_ext_ack *extack)
865 {
866 	struct net *net = sock_net(skb->sk);
867 	struct fib_config cfg;
868 	struct fib_table *tb;
869 	int err;
870 
871 	err = rtm_to_fib_config(net, skb, nlh, &cfg, extack);
872 	if (err < 0)
873 		goto errout;
874 
875 	if (cfg.fc_nh_id && !nexthop_find_by_id(net, cfg.fc_nh_id)) {
876 		NL_SET_ERR_MSG(extack, "Nexthop id does not exist");
877 		err = -EINVAL;
878 		goto errout;
879 	}
880 
881 	tb = fib_get_table(net, cfg.fc_table);
882 	if (!tb) {
883 		NL_SET_ERR_MSG(extack, "FIB table does not exist");
884 		err = -ESRCH;
885 		goto errout;
886 	}
887 
888 	err = fib_table_delete(net, tb, &cfg, extack);
889 errout:
890 	return err;
891 }
892 
inet_rtm_newroute(struct sk_buff * skb,struct nlmsghdr * nlh,struct netlink_ext_ack * extack)893 static int inet_rtm_newroute(struct sk_buff *skb, struct nlmsghdr *nlh,
894 			     struct netlink_ext_ack *extack)
895 {
896 	struct net *net = sock_net(skb->sk);
897 	struct fib_config cfg;
898 	struct fib_table *tb;
899 	int err;
900 
901 	err = rtm_to_fib_config(net, skb, nlh, &cfg, extack);
902 	if (err < 0)
903 		goto errout;
904 
905 	tb = fib_new_table(net, cfg.fc_table);
906 	if (!tb) {
907 		err = -ENOBUFS;
908 		goto errout;
909 	}
910 
911 	err = fib_table_insert(net, tb, &cfg, extack);
912 	if (!err && cfg.fc_type == RTN_LOCAL)
913 		net->ipv4.fib_has_custom_local_routes = true;
914 errout:
915 	return err;
916 }
917 
ip_valid_fib_dump_req(struct net * net,const struct nlmsghdr * nlh,struct fib_dump_filter * filter,struct netlink_callback * cb)918 int ip_valid_fib_dump_req(struct net *net, const struct nlmsghdr *nlh,
919 			  struct fib_dump_filter *filter,
920 			  struct netlink_callback *cb)
921 {
922 	struct netlink_ext_ack *extack = cb->extack;
923 	struct nlattr *tb[RTA_MAX + 1];
924 	struct rtmsg *rtm;
925 	int err, i;
926 
927 	if (filter->rtnl_held)
928 		ASSERT_RTNL();
929 
930 	if (nlh->nlmsg_len < nlmsg_msg_size(sizeof(*rtm))) {
931 		NL_SET_ERR_MSG(extack, "Invalid header for FIB dump request");
932 		return -EINVAL;
933 	}
934 
935 	rtm = nlmsg_data(nlh);
936 	if (rtm->rtm_dst_len || rtm->rtm_src_len  || rtm->rtm_tos   ||
937 	    rtm->rtm_scope) {
938 		NL_SET_ERR_MSG(extack, "Invalid values in header for FIB dump request");
939 		return -EINVAL;
940 	}
941 
942 	if (rtm->rtm_flags & ~(RTM_F_CLONED | RTM_F_PREFIX)) {
943 		NL_SET_ERR_MSG(extack, "Invalid flags for FIB dump request");
944 		return -EINVAL;
945 	}
946 	if (rtm->rtm_flags & RTM_F_CLONED)
947 		filter->dump_routes = false;
948 	else
949 		filter->dump_exceptions = false;
950 
951 	filter->flags    = rtm->rtm_flags;
952 	filter->protocol = rtm->rtm_protocol;
953 	filter->rt_type  = rtm->rtm_type;
954 	filter->table_id = rtm->rtm_table;
955 
956 	err = nlmsg_parse_deprecated_strict(nlh, sizeof(*rtm), tb, RTA_MAX,
957 					    rtm_ipv4_policy, extack);
958 	if (err < 0)
959 		return err;
960 
961 	for (i = 0; i <= RTA_MAX; ++i) {
962 		int ifindex;
963 
964 		if (!tb[i])
965 			continue;
966 
967 		switch (i) {
968 		case RTA_TABLE:
969 			filter->table_id = nla_get_u32(tb[i]);
970 			break;
971 		case RTA_OIF:
972 			ifindex = nla_get_u32(tb[i]);
973 			if (filter->rtnl_held)
974 				filter->dev = __dev_get_by_index(net, ifindex);
975 			else
976 				filter->dev = dev_get_by_index_rcu(net, ifindex);
977 			if (!filter->dev)
978 				return -ENODEV;
979 			break;
980 		default:
981 			NL_SET_ERR_MSG(extack, "Unsupported attribute in dump request");
982 			return -EINVAL;
983 		}
984 	}
985 
986 	if (filter->flags || filter->protocol || filter->rt_type ||
987 	    filter->table_id || filter->dev) {
988 		filter->filter_set = 1;
989 		cb->answer_flags = NLM_F_DUMP_FILTERED;
990 	}
991 
992 	return 0;
993 }
994 EXPORT_SYMBOL_GPL(ip_valid_fib_dump_req);
995 
inet_dump_fib(struct sk_buff * skb,struct netlink_callback * cb)996 static int inet_dump_fib(struct sk_buff *skb, struct netlink_callback *cb)
997 {
998 	struct fib_dump_filter filter = {
999 		.dump_routes = true,
1000 		.dump_exceptions = true,
1001 		.rtnl_held = false,
1002 	};
1003 	const struct nlmsghdr *nlh = cb->nlh;
1004 	struct net *net = sock_net(skb->sk);
1005 	unsigned int h, s_h;
1006 	unsigned int e = 0, s_e;
1007 	struct fib_table *tb;
1008 	struct hlist_head *head;
1009 	int dumped = 0, err = 0;
1010 
1011 	rcu_read_lock();
1012 	if (cb->strict_check) {
1013 		err = ip_valid_fib_dump_req(net, nlh, &filter, cb);
1014 		if (err < 0)
1015 			goto unlock;
1016 	} else if (nlmsg_len(nlh) >= sizeof(struct rtmsg)) {
1017 		struct rtmsg *rtm = nlmsg_data(nlh);
1018 
1019 		filter.flags = rtm->rtm_flags & (RTM_F_PREFIX | RTM_F_CLONED);
1020 	}
1021 
1022 	/* ipv4 does not use prefix flag */
1023 	if (filter.flags & RTM_F_PREFIX)
1024 		goto unlock;
1025 
1026 	if (filter.table_id) {
1027 		tb = fib_get_table(net, filter.table_id);
1028 		if (!tb) {
1029 			if (rtnl_msg_family(cb->nlh) != PF_INET)
1030 				goto unlock;
1031 
1032 			NL_SET_ERR_MSG(cb->extack, "ipv4: FIB table does not exist");
1033 			err = -ENOENT;
1034 			goto unlock;
1035 		}
1036 		err = fib_table_dump(tb, skb, cb, &filter);
1037 		goto unlock;
1038 	}
1039 
1040 	s_h = cb->args[0];
1041 	s_e = cb->args[1];
1042 
1043 	err = 0;
1044 	for (h = s_h; h < FIB_TABLE_HASHSZ; h++, s_e = 0) {
1045 		e = 0;
1046 		head = &net->ipv4.fib_table_hash[h];
1047 		hlist_for_each_entry_rcu(tb, head, tb_hlist) {
1048 			if (e < s_e)
1049 				goto next;
1050 			if (dumped)
1051 				memset(&cb->args[2], 0, sizeof(cb->args) -
1052 						 2 * sizeof(cb->args[0]));
1053 			err = fib_table_dump(tb, skb, cb, &filter);
1054 			if (err < 0)
1055 				goto out;
1056 			dumped = 1;
1057 next:
1058 			e++;
1059 		}
1060 	}
1061 out:
1062 
1063 	cb->args[1] = e;
1064 	cb->args[0] = h;
1065 
1066 unlock:
1067 	rcu_read_unlock();
1068 	return err;
1069 }
1070 
1071 /* Prepare and feed intra-kernel routing request.
1072  * Really, it should be netlink message, but :-( netlink
1073  * can be not configured, so that we feed it directly
1074  * to fib engine. It is legal, because all events occur
1075  * only when netlink is already locked.
1076  */
fib_magic(int cmd,int type,__be32 dst,int dst_len,struct in_ifaddr * ifa,u32 rt_priority)1077 static void fib_magic(int cmd, int type, __be32 dst, int dst_len,
1078 		      struct in_ifaddr *ifa, u32 rt_priority)
1079 {
1080 	struct net *net = dev_net(ifa->ifa_dev->dev);
1081 	u32 tb_id = l3mdev_fib_table(ifa->ifa_dev->dev);
1082 	struct fib_table *tb;
1083 	struct fib_config cfg = {
1084 		.fc_protocol = RTPROT_KERNEL,
1085 		.fc_type = type,
1086 		.fc_dst = dst,
1087 		.fc_dst_len = dst_len,
1088 		.fc_priority = rt_priority,
1089 		.fc_prefsrc = ifa->ifa_local,
1090 		.fc_oif = ifa->ifa_dev->dev->ifindex,
1091 		.fc_nlflags = NLM_F_CREATE | NLM_F_APPEND,
1092 		.fc_nlinfo = {
1093 			.nl_net = net,
1094 		},
1095 	};
1096 
1097 	if (!tb_id)
1098 		tb_id = (type == RTN_UNICAST) ? RT_TABLE_MAIN : RT_TABLE_LOCAL;
1099 
1100 	tb = fib_new_table(net, tb_id);
1101 	if (!tb)
1102 		return;
1103 
1104 	cfg.fc_table = tb->tb_id;
1105 
1106 	if (type != RTN_LOCAL)
1107 		cfg.fc_scope = RT_SCOPE_LINK;
1108 	else
1109 		cfg.fc_scope = RT_SCOPE_HOST;
1110 
1111 	if (cmd == RTM_NEWROUTE)
1112 		fib_table_insert(net, tb, &cfg, NULL);
1113 	else
1114 		fib_table_delete(net, tb, &cfg, NULL);
1115 }
1116 
fib_add_ifaddr(struct in_ifaddr * ifa)1117 void fib_add_ifaddr(struct in_ifaddr *ifa)
1118 {
1119 	struct in_device *in_dev = ifa->ifa_dev;
1120 	struct net_device *dev = in_dev->dev;
1121 	struct in_ifaddr *prim = ifa;
1122 	__be32 mask = ifa->ifa_mask;
1123 	__be32 addr = ifa->ifa_local;
1124 	__be32 prefix = ifa->ifa_address & mask;
1125 
1126 	if (ifa->ifa_flags & IFA_F_SECONDARY) {
1127 		prim = inet_ifa_byprefix(in_dev, prefix, mask);
1128 		if (!prim) {
1129 			pr_warn("%s: bug: prim == NULL\n", __func__);
1130 			return;
1131 		}
1132 	}
1133 
1134 	fib_magic(RTM_NEWROUTE, RTN_LOCAL, addr, 32, prim, 0);
1135 
1136 	if (!(dev->flags & IFF_UP))
1137 		return;
1138 
1139 	/* Add broadcast address, if it is explicitly assigned. */
1140 	if (ifa->ifa_broadcast && ifa->ifa_broadcast != htonl(0xFFFFFFFF)) {
1141 		fib_magic(RTM_NEWROUTE, RTN_BROADCAST, ifa->ifa_broadcast, 32,
1142 			  prim, 0);
1143 		arp_invalidate(dev, ifa->ifa_broadcast, false);
1144 	}
1145 
1146 	if (!ipv4_is_zeronet(prefix) && !(ifa->ifa_flags & IFA_F_SECONDARY) &&
1147 	    (prefix != addr || ifa->ifa_prefixlen < 32)) {
1148 		if (!(ifa->ifa_flags & IFA_F_NOPREFIXROUTE))
1149 			fib_magic(RTM_NEWROUTE,
1150 				  dev->flags & IFF_LOOPBACK ? RTN_LOCAL : RTN_UNICAST,
1151 				  prefix, ifa->ifa_prefixlen, prim,
1152 				  ifa->ifa_rt_priority);
1153 
1154 		/* Add the network broadcast address, when it makes sense */
1155 		if (ifa->ifa_prefixlen < 31) {
1156 			fib_magic(RTM_NEWROUTE, RTN_BROADCAST, prefix | ~mask,
1157 				  32, prim, 0);
1158 			arp_invalidate(dev, prefix | ~mask, false);
1159 		}
1160 	}
1161 }
1162 
fib_modify_prefix_metric(struct in_ifaddr * ifa,u32 new_metric)1163 void fib_modify_prefix_metric(struct in_ifaddr *ifa, u32 new_metric)
1164 {
1165 	__be32 prefix = ifa->ifa_address & ifa->ifa_mask;
1166 	struct in_device *in_dev = ifa->ifa_dev;
1167 	struct net_device *dev = in_dev->dev;
1168 
1169 	if (!(dev->flags & IFF_UP) ||
1170 	    ifa->ifa_flags & (IFA_F_SECONDARY | IFA_F_NOPREFIXROUTE) ||
1171 	    ipv4_is_zeronet(prefix) ||
1172 	    (prefix == ifa->ifa_local && ifa->ifa_prefixlen == 32))
1173 		return;
1174 
1175 	/* add the new */
1176 	fib_magic(RTM_NEWROUTE,
1177 		  dev->flags & IFF_LOOPBACK ? RTN_LOCAL : RTN_UNICAST,
1178 		  prefix, ifa->ifa_prefixlen, ifa, new_metric);
1179 
1180 	/* delete the old */
1181 	fib_magic(RTM_DELROUTE,
1182 		  dev->flags & IFF_LOOPBACK ? RTN_LOCAL : RTN_UNICAST,
1183 		  prefix, ifa->ifa_prefixlen, ifa, ifa->ifa_rt_priority);
1184 }
1185 
1186 /* Delete primary or secondary address.
1187  * Optionally, on secondary address promotion consider the addresses
1188  * from subnet iprim as deleted, even if they are in device list.
1189  * In this case the secondary ifa can be in device list.
1190  */
fib_del_ifaddr(struct in_ifaddr * ifa,struct in_ifaddr * iprim)1191 void fib_del_ifaddr(struct in_ifaddr *ifa, struct in_ifaddr *iprim)
1192 {
1193 	struct in_device *in_dev = ifa->ifa_dev;
1194 	struct net_device *dev = in_dev->dev;
1195 	struct in_ifaddr *ifa1;
1196 	struct in_ifaddr *prim = ifa, *prim1 = NULL;
1197 	__be32 brd = ifa->ifa_address | ~ifa->ifa_mask;
1198 	__be32 any = ifa->ifa_address & ifa->ifa_mask;
1199 #define LOCAL_OK	1
1200 #define BRD_OK		2
1201 #define BRD0_OK		4
1202 #define BRD1_OK		8
1203 	unsigned int ok = 0;
1204 	int subnet = 0;		/* Primary network */
1205 	int gone = 1;		/* Address is missing */
1206 	int same_prefsrc = 0;	/* Another primary with same IP */
1207 
1208 	if (ifa->ifa_flags & IFA_F_SECONDARY) {
1209 		prim = inet_ifa_byprefix(in_dev, any, ifa->ifa_mask);
1210 		if (!prim) {
1211 			/* if the device has been deleted, we don't perform
1212 			 * address promotion
1213 			 */
1214 			if (!in_dev->dead)
1215 				pr_warn("%s: bug: prim == NULL\n", __func__);
1216 			return;
1217 		}
1218 		if (iprim && iprim != prim) {
1219 			pr_warn("%s: bug: iprim != prim\n", __func__);
1220 			return;
1221 		}
1222 	} else if (!ipv4_is_zeronet(any) &&
1223 		   (any != ifa->ifa_local || ifa->ifa_prefixlen < 32)) {
1224 		if (!(ifa->ifa_flags & IFA_F_NOPREFIXROUTE))
1225 			fib_magic(RTM_DELROUTE,
1226 				  dev->flags & IFF_LOOPBACK ? RTN_LOCAL : RTN_UNICAST,
1227 				  any, ifa->ifa_prefixlen, prim, 0);
1228 		subnet = 1;
1229 	}
1230 
1231 	if (in_dev->dead)
1232 		goto no_promotions;
1233 
1234 	/* Deletion is more complicated than add.
1235 	 * We should take care of not to delete too much :-)
1236 	 *
1237 	 * Scan address list to be sure that addresses are really gone.
1238 	 */
1239 	rcu_read_lock();
1240 	in_dev_for_each_ifa_rcu(ifa1, in_dev) {
1241 		if (ifa1 == ifa) {
1242 			/* promotion, keep the IP */
1243 			gone = 0;
1244 			continue;
1245 		}
1246 		/* Ignore IFAs from our subnet */
1247 		if (iprim && ifa1->ifa_mask == iprim->ifa_mask &&
1248 		    inet_ifa_match(ifa1->ifa_address, iprim))
1249 			continue;
1250 
1251 		/* Ignore ifa1 if it uses different primary IP (prefsrc) */
1252 		if (ifa1->ifa_flags & IFA_F_SECONDARY) {
1253 			/* Another address from our subnet? */
1254 			if (ifa1->ifa_mask == prim->ifa_mask &&
1255 			    inet_ifa_match(ifa1->ifa_address, prim))
1256 				prim1 = prim;
1257 			else {
1258 				/* We reached the secondaries, so
1259 				 * same_prefsrc should be determined.
1260 				 */
1261 				if (!same_prefsrc)
1262 					continue;
1263 				/* Search new prim1 if ifa1 is not
1264 				 * using the current prim1
1265 				 */
1266 				if (!prim1 ||
1267 				    ifa1->ifa_mask != prim1->ifa_mask ||
1268 				    !inet_ifa_match(ifa1->ifa_address, prim1))
1269 					prim1 = inet_ifa_byprefix(in_dev,
1270 							ifa1->ifa_address,
1271 							ifa1->ifa_mask);
1272 				if (!prim1)
1273 					continue;
1274 				if (prim1->ifa_local != prim->ifa_local)
1275 					continue;
1276 			}
1277 		} else {
1278 			if (prim->ifa_local != ifa1->ifa_local)
1279 				continue;
1280 			prim1 = ifa1;
1281 			if (prim != prim1)
1282 				same_prefsrc = 1;
1283 		}
1284 		if (ifa->ifa_local == ifa1->ifa_local)
1285 			ok |= LOCAL_OK;
1286 		if (ifa->ifa_broadcast == ifa1->ifa_broadcast)
1287 			ok |= BRD_OK;
1288 		if (brd == ifa1->ifa_broadcast)
1289 			ok |= BRD1_OK;
1290 		if (any == ifa1->ifa_broadcast)
1291 			ok |= BRD0_OK;
1292 		/* primary has network specific broadcasts */
1293 		if (prim1 == ifa1 && ifa1->ifa_prefixlen < 31) {
1294 			__be32 brd1 = ifa1->ifa_address | ~ifa1->ifa_mask;
1295 			__be32 any1 = ifa1->ifa_address & ifa1->ifa_mask;
1296 
1297 			if (!ipv4_is_zeronet(any1)) {
1298 				if (ifa->ifa_broadcast == brd1 ||
1299 				    ifa->ifa_broadcast == any1)
1300 					ok |= BRD_OK;
1301 				if (brd == brd1 || brd == any1)
1302 					ok |= BRD1_OK;
1303 				if (any == brd1 || any == any1)
1304 					ok |= BRD0_OK;
1305 			}
1306 		}
1307 	}
1308 	rcu_read_unlock();
1309 
1310 no_promotions:
1311 	if (!(ok & BRD_OK))
1312 		fib_magic(RTM_DELROUTE, RTN_BROADCAST, ifa->ifa_broadcast, 32,
1313 			  prim, 0);
1314 	if (subnet && ifa->ifa_prefixlen < 31) {
1315 		if (!(ok & BRD1_OK))
1316 			fib_magic(RTM_DELROUTE, RTN_BROADCAST, brd, 32,
1317 				  prim, 0);
1318 		if (!(ok & BRD0_OK))
1319 			fib_magic(RTM_DELROUTE, RTN_BROADCAST, any, 32,
1320 				  prim, 0);
1321 	}
1322 	if (!(ok & LOCAL_OK)) {
1323 		unsigned int addr_type;
1324 
1325 		fib_magic(RTM_DELROUTE, RTN_LOCAL, ifa->ifa_local, 32, prim, 0);
1326 
1327 		/* Check, that this local address finally disappeared. */
1328 		addr_type = inet_addr_type_dev_table(dev_net(dev), dev,
1329 						     ifa->ifa_local);
1330 		if (gone && addr_type != RTN_LOCAL) {
1331 			/* And the last, but not the least thing.
1332 			 * We must flush stray FIB entries.
1333 			 *
1334 			 * First of all, we scan fib_info list searching
1335 			 * for stray nexthop entries, then ignite fib_flush.
1336 			 */
1337 			if (fib_sync_down_addr(dev, ifa->ifa_local))
1338 				fib_flush(dev_net(dev));
1339 		}
1340 	}
1341 #undef LOCAL_OK
1342 #undef BRD_OK
1343 #undef BRD0_OK
1344 #undef BRD1_OK
1345 }
1346 
nl_fib_lookup(struct net * net,struct fib_result_nl * frn)1347 static void nl_fib_lookup(struct net *net, struct fib_result_nl *frn)
1348 {
1349 
1350 	struct fib_result       res;
1351 	struct flowi4           fl4 = {
1352 		.flowi4_mark = frn->fl_mark,
1353 		.daddr = frn->fl_addr,
1354 		.flowi4_tos = frn->fl_tos & INET_DSCP_MASK,
1355 		.flowi4_scope = frn->fl_scope,
1356 	};
1357 	struct fib_table *tb;
1358 
1359 	rcu_read_lock();
1360 
1361 	tb = fib_get_table(net, frn->tb_id_in);
1362 
1363 	frn->err = -ENOENT;
1364 	if (tb) {
1365 		local_bh_disable();
1366 
1367 		frn->tb_id = tb->tb_id;
1368 		frn->err = fib_table_lookup(tb, &fl4, &res, FIB_LOOKUP_NOREF);
1369 
1370 		if (!frn->err) {
1371 			frn->prefixlen = res.prefixlen;
1372 			frn->nh_sel = res.nh_sel;
1373 			frn->type = res.type;
1374 			frn->scope = res.scope;
1375 		}
1376 		local_bh_enable();
1377 	}
1378 
1379 	rcu_read_unlock();
1380 }
1381 
nl_fib_input(struct sk_buff * skb)1382 static void nl_fib_input(struct sk_buff *skb)
1383 {
1384 	struct net *net;
1385 	struct fib_result_nl *frn;
1386 	struct nlmsghdr *nlh;
1387 	u32 portid;
1388 
1389 	net = sock_net(skb->sk);
1390 	nlh = nlmsg_hdr(skb);
1391 	if (skb->len < nlmsg_total_size(sizeof(*frn)) ||
1392 	    skb->len < nlh->nlmsg_len ||
1393 	    nlmsg_len(nlh) < sizeof(*frn))
1394 		return;
1395 
1396 	skb = netlink_skb_clone(skb, GFP_KERNEL);
1397 	if (!skb)
1398 		return;
1399 	nlh = nlmsg_hdr(skb);
1400 
1401 	frn = nlmsg_data(nlh);
1402 	nl_fib_lookup(net, frn);
1403 
1404 	portid = NETLINK_CB(skb).portid;      /* netlink portid */
1405 	NETLINK_CB(skb).portid = 0;        /* from kernel */
1406 	NETLINK_CB(skb).dst_group = 0;  /* unicast */
1407 	nlmsg_unicast(net->ipv4.fibnl, skb, portid);
1408 }
1409 
nl_fib_lookup_init(struct net * net)1410 static int __net_init nl_fib_lookup_init(struct net *net)
1411 {
1412 	struct sock *sk;
1413 	struct netlink_kernel_cfg cfg = {
1414 		.input	= nl_fib_input,
1415 	};
1416 
1417 	sk = netlink_kernel_create(net, NETLINK_FIB_LOOKUP, &cfg);
1418 	if (!sk)
1419 		return -EAFNOSUPPORT;
1420 	net->ipv4.fibnl = sk;
1421 	return 0;
1422 }
1423 
nl_fib_lookup_exit(struct net * net)1424 static void nl_fib_lookup_exit(struct net *net)
1425 {
1426 	netlink_kernel_release(net->ipv4.fibnl);
1427 	net->ipv4.fibnl = NULL;
1428 }
1429 
fib_disable_ip(struct net_device * dev,unsigned long event,bool force)1430 static void fib_disable_ip(struct net_device *dev, unsigned long event,
1431 			   bool force)
1432 {
1433 	if (fib_sync_down_dev(dev, event, force))
1434 		fib_flush(dev_net(dev));
1435 	else
1436 		rt_cache_flush(dev_net(dev));
1437 	arp_ifdown(dev);
1438 }
1439 
fib_inetaddr_event(struct notifier_block * this,unsigned long event,void * ptr)1440 static int fib_inetaddr_event(struct notifier_block *this, unsigned long event, void *ptr)
1441 {
1442 	struct in_ifaddr *ifa = ptr;
1443 	struct net_device *dev = ifa->ifa_dev->dev;
1444 	struct net *net = dev_net(dev);
1445 
1446 	switch (event) {
1447 	case NETDEV_UP:
1448 		fib_add_ifaddr(ifa);
1449 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1450 		fib_sync_up(dev, RTNH_F_DEAD);
1451 #endif
1452 		atomic_inc(&net->ipv4.dev_addr_genid);
1453 		rt_cache_flush(dev_net(dev));
1454 		break;
1455 	case NETDEV_DOWN:
1456 		fib_del_ifaddr(ifa, NULL);
1457 		atomic_inc(&net->ipv4.dev_addr_genid);
1458 		if (!ifa->ifa_dev->ifa_list) {
1459 			/* Last address was deleted from this interface.
1460 			 * Disable IP.
1461 			 */
1462 			fib_disable_ip(dev, event, true);
1463 		} else {
1464 			rt_cache_flush(dev_net(dev));
1465 		}
1466 		break;
1467 	}
1468 	return NOTIFY_DONE;
1469 }
1470 
fib_netdev_event(struct notifier_block * this,unsigned long event,void * ptr)1471 static int fib_netdev_event(struct notifier_block *this, unsigned long event, void *ptr)
1472 {
1473 	struct net_device *dev = netdev_notifier_info_to_dev(ptr);
1474 	struct netdev_notifier_changeupper_info *upper_info = ptr;
1475 	struct netdev_notifier_info_ext *info_ext = ptr;
1476 	struct in_device *in_dev;
1477 	struct net *net = dev_net(dev);
1478 	struct in_ifaddr *ifa;
1479 	unsigned int flags;
1480 
1481 	if (event == NETDEV_UNREGISTER) {
1482 		fib_disable_ip(dev, event, true);
1483 		rt_flush_dev(dev);
1484 		return NOTIFY_DONE;
1485 	}
1486 
1487 	in_dev = __in_dev_get_rtnl(dev);
1488 	if (!in_dev)
1489 		return NOTIFY_DONE;
1490 
1491 	switch (event) {
1492 	case NETDEV_UP:
1493 		in_dev_for_each_ifa_rtnl(ifa, in_dev) {
1494 			fib_add_ifaddr(ifa);
1495 		}
1496 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1497 		fib_sync_up(dev, RTNH_F_DEAD);
1498 #endif
1499 		atomic_inc(&net->ipv4.dev_addr_genid);
1500 		rt_cache_flush(net);
1501 		break;
1502 	case NETDEV_DOWN:
1503 		fib_disable_ip(dev, event, false);
1504 		break;
1505 	case NETDEV_CHANGE:
1506 		flags = dev_get_flags(dev);
1507 		if (flags & (IFF_RUNNING | IFF_LOWER_UP))
1508 			fib_sync_up(dev, RTNH_F_LINKDOWN);
1509 		else
1510 			fib_sync_down_dev(dev, event, false);
1511 		rt_cache_flush(net);
1512 		break;
1513 	case NETDEV_CHANGEMTU:
1514 		fib_sync_mtu(dev, info_ext->ext.mtu);
1515 		rt_cache_flush(net);
1516 		break;
1517 	case NETDEV_CHANGEUPPER:
1518 		upper_info = ptr;
1519 		/* flush all routes if dev is linked to or unlinked from
1520 		 * an L3 master device (e.g., VRF)
1521 		 */
1522 		if (upper_info->upper_dev &&
1523 		    netif_is_l3_master(upper_info->upper_dev))
1524 			fib_disable_ip(dev, NETDEV_DOWN, true);
1525 		break;
1526 	}
1527 	return NOTIFY_DONE;
1528 }
1529 
1530 static struct notifier_block fib_inetaddr_notifier = {
1531 	.notifier_call = fib_inetaddr_event,
1532 };
1533 
1534 static struct notifier_block fib_netdev_notifier = {
1535 	.notifier_call = fib_netdev_event,
1536 };
1537 
ip_fib_net_init(struct net * net)1538 static int __net_init ip_fib_net_init(struct net *net)
1539 {
1540 	int err;
1541 	size_t size = sizeof(struct hlist_head) * FIB_TABLE_HASHSZ;
1542 
1543 	err = fib4_notifier_init(net);
1544 	if (err)
1545 		return err;
1546 
1547 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1548 	/* Default to 3-tuple */
1549 	net->ipv4.sysctl_fib_multipath_hash_fields =
1550 		FIB_MULTIPATH_HASH_FIELD_DEFAULT_MASK;
1551 #endif
1552 
1553 	/* Avoid false sharing : Use at least a full cache line */
1554 	size = max_t(size_t, size, L1_CACHE_BYTES);
1555 
1556 	net->ipv4.fib_table_hash = kzalloc(size, GFP_KERNEL);
1557 	if (!net->ipv4.fib_table_hash) {
1558 		err = -ENOMEM;
1559 		goto err_table_hash_alloc;
1560 	}
1561 
1562 	err = fib4_rules_init(net);
1563 	if (err < 0)
1564 		goto err_rules_init;
1565 	return 0;
1566 
1567 err_rules_init:
1568 	kfree(net->ipv4.fib_table_hash);
1569 err_table_hash_alloc:
1570 	fib4_notifier_exit(net);
1571 	return err;
1572 }
1573 
ip_fib_net_exit(struct net * net)1574 static void ip_fib_net_exit(struct net *net)
1575 {
1576 	int i;
1577 
1578 	ASSERT_RTNL();
1579 #ifdef CONFIG_IP_MULTIPLE_TABLES
1580 	RCU_INIT_POINTER(net->ipv4.fib_main, NULL);
1581 	RCU_INIT_POINTER(net->ipv4.fib_default, NULL);
1582 #endif
1583 	/* Destroy the tables in reverse order to guarantee that the
1584 	 * local table, ID 255, is destroyed before the main table, ID
1585 	 * 254. This is necessary as the local table may contain
1586 	 * references to data contained in the main table.
1587 	 */
1588 	for (i = FIB_TABLE_HASHSZ - 1; i >= 0; i--) {
1589 		struct hlist_head *head = &net->ipv4.fib_table_hash[i];
1590 		struct hlist_node *tmp;
1591 		struct fib_table *tb;
1592 
1593 		hlist_for_each_entry_safe(tb, tmp, head, tb_hlist) {
1594 			hlist_del(&tb->tb_hlist);
1595 			fib_table_flush(net, tb, true);
1596 			fib_free_table(tb);
1597 		}
1598 	}
1599 
1600 #ifdef CONFIG_IP_MULTIPLE_TABLES
1601 	fib4_rules_exit(net);
1602 #endif
1603 
1604 	kfree(net->ipv4.fib_table_hash);
1605 	fib4_notifier_exit(net);
1606 }
1607 
fib_net_init(struct net * net)1608 static int __net_init fib_net_init(struct net *net)
1609 {
1610 	int error;
1611 
1612 #ifdef CONFIG_IP_ROUTE_CLASSID
1613 	atomic_set(&net->ipv4.fib_num_tclassid_users, 0);
1614 #endif
1615 	error = ip_fib_net_init(net);
1616 	if (error < 0)
1617 		goto out;
1618 	error = nl_fib_lookup_init(net);
1619 	if (error < 0)
1620 		goto out_nlfl;
1621 	error = fib_proc_init(net);
1622 	if (error < 0)
1623 		goto out_proc;
1624 out:
1625 	return error;
1626 
1627 out_proc:
1628 	nl_fib_lookup_exit(net);
1629 out_nlfl:
1630 	rtnl_lock();
1631 	ip_fib_net_exit(net);
1632 	rtnl_unlock();
1633 	goto out;
1634 }
1635 
fib_net_exit(struct net * net)1636 static void __net_exit fib_net_exit(struct net *net)
1637 {
1638 	fib_proc_exit(net);
1639 	nl_fib_lookup_exit(net);
1640 }
1641 
fib_net_exit_batch(struct list_head * net_list)1642 static void __net_exit fib_net_exit_batch(struct list_head *net_list)
1643 {
1644 	struct net *net;
1645 
1646 	rtnl_lock();
1647 	list_for_each_entry(net, net_list, exit_list)
1648 		ip_fib_net_exit(net);
1649 
1650 	rtnl_unlock();
1651 }
1652 
1653 static struct pernet_operations fib_net_ops = {
1654 	.init = fib_net_init,
1655 	.exit = fib_net_exit,
1656 	.exit_batch = fib_net_exit_batch,
1657 };
1658 
1659 static const struct rtnl_msg_handler fib_rtnl_msg_handlers[] __initconst = {
1660 	{.protocol = PF_INET, .msgtype = RTM_NEWROUTE,
1661 	 .doit = inet_rtm_newroute},
1662 	{.protocol = PF_INET, .msgtype = RTM_DELROUTE,
1663 	 .doit = inet_rtm_delroute},
1664 	{.protocol = PF_INET, .msgtype = RTM_GETROUTE, .dumpit = inet_dump_fib,
1665 	 .flags = RTNL_FLAG_DUMP_UNLOCKED | RTNL_FLAG_DUMP_SPLIT_NLM_DONE},
1666 };
1667 
ip_fib_init(void)1668 void __init ip_fib_init(void)
1669 {
1670 	fib_trie_init();
1671 
1672 	register_pernet_subsys(&fib_net_ops);
1673 
1674 	register_netdevice_notifier(&fib_netdev_notifier);
1675 	register_inetaddr_notifier(&fib_inetaddr_notifier);
1676 
1677 	rtnl_register_many(fib_rtnl_msg_handlers);
1678 }
1679