xref: /openbmc/linux/net/ipv4/fib_rules.c (revision b96fc2f3)
1 /*
2  * INET		An implementation of the TCP/IP protocol suite for the LINUX
3  *		operating system.  INET is implemented using the  BSD Socket
4  *		interface as the means of communication with the user level.
5  *
6  *		IPv4 Forwarding Information Base: policy rules.
7  *
8  * Authors:	Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
9  *		Thomas Graf <tgraf@suug.ch>
10  *
11  *		This program is free software; you can redistribute it and/or
12  *		modify it under the terms of the GNU General Public License
13  *		as published by the Free Software Foundation; either version
14  *		2 of the License, or (at your option) any later version.
15  *
16  * Fixes:
17  *		Rani Assaf	:	local_rule cannot be deleted
18  *		Marc Boucher	:	routing by fwmark
19  */
20 
21 #include <linux/types.h>
22 #include <linux/kernel.h>
23 #include <linux/netdevice.h>
24 #include <linux/netlink.h>
25 #include <linux/inetdevice.h>
26 #include <linux/init.h>
27 #include <linux/list.h>
28 #include <linux/rcupdate.h>
29 #include <linux/export.h>
30 #include <net/ip.h>
31 #include <net/route.h>
32 #include <net/tcp.h>
33 #include <net/ip_fib.h>
34 #include <net/fib_rules.h>
35 
36 struct fib4_rule {
37 	struct fib_rule		common;
38 	u8			dst_len;
39 	u8			src_len;
40 	u8			tos;
41 	__be32			src;
42 	__be32			srcmask;
43 	__be32			dst;
44 	__be32			dstmask;
45 #ifdef CONFIG_IP_ROUTE_CLASSID
46 	u32			tclassid;
47 #endif
48 };
49 
50 int __fib_lookup(struct net *net, struct flowi4 *flp,
51 		 struct fib_result *res, unsigned int flags)
52 {
53 	struct fib_lookup_arg arg = {
54 		.result = res,
55 		.flags = flags,
56 	};
57 	int err;
58 
59 	err = fib_rules_lookup(net->ipv4.rules_ops, flowi4_to_flowi(flp), 0, &arg);
60 #ifdef CONFIG_IP_ROUTE_CLASSID
61 	if (arg.rule)
62 		res->tclassid = ((struct fib4_rule *)arg.rule)->tclassid;
63 	else
64 		res->tclassid = 0;
65 #endif
66 
67 	if (err == -ESRCH)
68 		err = -ENETUNREACH;
69 
70 	return err;
71 }
72 EXPORT_SYMBOL_GPL(__fib_lookup);
73 
74 static int fib4_rule_action(struct fib_rule *rule, struct flowi *flp,
75 			    int flags, struct fib_lookup_arg *arg)
76 {
77 	int err = -EAGAIN;
78 	struct fib_table *tbl;
79 
80 	switch (rule->action) {
81 	case FR_ACT_TO_TBL:
82 		break;
83 
84 	case FR_ACT_UNREACHABLE:
85 		return -ENETUNREACH;
86 
87 	case FR_ACT_PROHIBIT:
88 		return -EACCES;
89 
90 	case FR_ACT_BLACKHOLE:
91 	default:
92 		return -EINVAL;
93 	}
94 
95 	rcu_read_lock();
96 
97 	tbl = fib_get_table(rule->fr_net, rule->table);
98 	if (tbl)
99 		err = fib_table_lookup(tbl, &flp->u.ip4,
100 				       (struct fib_result *)arg->result,
101 				       arg->flags);
102 
103 	rcu_read_unlock();
104 	return err;
105 }
106 
107 static bool fib4_rule_suppress(struct fib_rule *rule, struct fib_lookup_arg *arg)
108 {
109 	struct fib_result *result = (struct fib_result *) arg->result;
110 	struct net_device *dev = NULL;
111 
112 	if (result->fi)
113 		dev = result->fi->fib_dev;
114 
115 	/* do not accept result if the route does
116 	 * not meet the required prefix length
117 	 */
118 	if (result->prefixlen <= rule->suppress_prefixlen)
119 		goto suppress_route;
120 
121 	/* do not accept result if the route uses a device
122 	 * belonging to a forbidden interface group
123 	 */
124 	if (rule->suppress_ifgroup != -1 && dev && dev->group == rule->suppress_ifgroup)
125 		goto suppress_route;
126 
127 	return false;
128 
129 suppress_route:
130 	if (!(arg->flags & FIB_LOOKUP_NOREF))
131 		fib_info_put(result->fi);
132 	return true;
133 }
134 
135 static int fib4_rule_match(struct fib_rule *rule, struct flowi *fl, int flags)
136 {
137 	struct fib4_rule *r = (struct fib4_rule *) rule;
138 	struct flowi4 *fl4 = &fl->u.ip4;
139 	__be32 daddr = fl4->daddr;
140 	__be32 saddr = fl4->saddr;
141 
142 	if (((saddr ^ r->src) & r->srcmask) ||
143 	    ((daddr ^ r->dst) & r->dstmask))
144 		return 0;
145 
146 	if (r->tos && (r->tos != fl4->flowi4_tos))
147 		return 0;
148 
149 	return 1;
150 }
151 
152 static struct fib_table *fib_empty_table(struct net *net)
153 {
154 	u32 id;
155 
156 	for (id = 1; id <= RT_TABLE_MAX; id++)
157 		if (!fib_get_table(net, id))
158 			return fib_new_table(net, id);
159 	return NULL;
160 }
161 
162 static const struct nla_policy fib4_rule_policy[FRA_MAX+1] = {
163 	FRA_GENERIC_POLICY,
164 	[FRA_FLOW]	= { .type = NLA_U32 },
165 };
166 
167 static int fib4_rule_configure(struct fib_rule *rule, struct sk_buff *skb,
168 			       struct fib_rule_hdr *frh,
169 			       struct nlattr **tb)
170 {
171 	struct net *net = sock_net(skb->sk);
172 	int err = -EINVAL;
173 	struct fib4_rule *rule4 = (struct fib4_rule *) rule;
174 
175 	if (frh->tos & ~IPTOS_TOS_MASK)
176 		goto errout;
177 
178 	/* split local/main if they are not already split */
179 	err = fib_unmerge(net);
180 	if (err)
181 		goto errout;
182 
183 	if (rule->table == RT_TABLE_UNSPEC) {
184 		if (rule->action == FR_ACT_TO_TBL) {
185 			struct fib_table *table;
186 
187 			table = fib_empty_table(net);
188 			if (!table) {
189 				err = -ENOBUFS;
190 				goto errout;
191 			}
192 
193 			rule->table = table->tb_id;
194 		}
195 	}
196 
197 	if (frh->src_len)
198 		rule4->src = nla_get_in_addr(tb[FRA_SRC]);
199 
200 	if (frh->dst_len)
201 		rule4->dst = nla_get_in_addr(tb[FRA_DST]);
202 
203 #ifdef CONFIG_IP_ROUTE_CLASSID
204 	if (tb[FRA_FLOW]) {
205 		rule4->tclassid = nla_get_u32(tb[FRA_FLOW]);
206 		if (rule4->tclassid)
207 			net->ipv4.fib_num_tclassid_users++;
208 	}
209 #endif
210 
211 	rule4->src_len = frh->src_len;
212 	rule4->srcmask = inet_make_mask(rule4->src_len);
213 	rule4->dst_len = frh->dst_len;
214 	rule4->dstmask = inet_make_mask(rule4->dst_len);
215 	rule4->tos = frh->tos;
216 
217 	net->ipv4.fib_has_custom_rules = true;
218 	fib_flush_external(rule->fr_net);
219 
220 	err = 0;
221 errout:
222 	return err;
223 }
224 
225 static int fib4_rule_delete(struct fib_rule *rule)
226 {
227 	struct net *net = rule->fr_net;
228 	int err;
229 
230 	/* split local/main if they are not already split */
231 	err = fib_unmerge(net);
232 	if (err)
233 		goto errout;
234 
235 #ifdef CONFIG_IP_ROUTE_CLASSID
236 	if (((struct fib4_rule *)rule)->tclassid)
237 		net->ipv4.fib_num_tclassid_users--;
238 #endif
239 	net->ipv4.fib_has_custom_rules = true;
240 	fib_flush_external(rule->fr_net);
241 errout:
242 	return err;
243 }
244 
245 static int fib4_rule_compare(struct fib_rule *rule, struct fib_rule_hdr *frh,
246 			     struct nlattr **tb)
247 {
248 	struct fib4_rule *rule4 = (struct fib4_rule *) rule;
249 
250 	if (frh->src_len && (rule4->src_len != frh->src_len))
251 		return 0;
252 
253 	if (frh->dst_len && (rule4->dst_len != frh->dst_len))
254 		return 0;
255 
256 	if (frh->tos && (rule4->tos != frh->tos))
257 		return 0;
258 
259 #ifdef CONFIG_IP_ROUTE_CLASSID
260 	if (tb[FRA_FLOW] && (rule4->tclassid != nla_get_u32(tb[FRA_FLOW])))
261 		return 0;
262 #endif
263 
264 	if (frh->src_len && (rule4->src != nla_get_in_addr(tb[FRA_SRC])))
265 		return 0;
266 
267 	if (frh->dst_len && (rule4->dst != nla_get_in_addr(tb[FRA_DST])))
268 		return 0;
269 
270 	return 1;
271 }
272 
273 static int fib4_rule_fill(struct fib_rule *rule, struct sk_buff *skb,
274 			  struct fib_rule_hdr *frh)
275 {
276 	struct fib4_rule *rule4 = (struct fib4_rule *) rule;
277 
278 	frh->dst_len = rule4->dst_len;
279 	frh->src_len = rule4->src_len;
280 	frh->tos = rule4->tos;
281 
282 	if ((rule4->dst_len &&
283 	     nla_put_in_addr(skb, FRA_DST, rule4->dst)) ||
284 	    (rule4->src_len &&
285 	     nla_put_in_addr(skb, FRA_SRC, rule4->src)))
286 		goto nla_put_failure;
287 #ifdef CONFIG_IP_ROUTE_CLASSID
288 	if (rule4->tclassid &&
289 	    nla_put_u32(skb, FRA_FLOW, rule4->tclassid))
290 		goto nla_put_failure;
291 #endif
292 	return 0;
293 
294 nla_put_failure:
295 	return -ENOBUFS;
296 }
297 
298 static size_t fib4_rule_nlmsg_payload(struct fib_rule *rule)
299 {
300 	return nla_total_size(4) /* dst */
301 	       + nla_total_size(4) /* src */
302 	       + nla_total_size(4); /* flow */
303 }
304 
305 static void fib4_rule_flush_cache(struct fib_rules_ops *ops)
306 {
307 	rt_cache_flush(ops->fro_net);
308 }
309 
310 static const struct fib_rules_ops __net_initconst fib4_rules_ops_template = {
311 	.family		= AF_INET,
312 	.rule_size	= sizeof(struct fib4_rule),
313 	.addr_size	= sizeof(u32),
314 	.action		= fib4_rule_action,
315 	.suppress	= fib4_rule_suppress,
316 	.match		= fib4_rule_match,
317 	.configure	= fib4_rule_configure,
318 	.delete		= fib4_rule_delete,
319 	.compare	= fib4_rule_compare,
320 	.fill		= fib4_rule_fill,
321 	.nlmsg_payload	= fib4_rule_nlmsg_payload,
322 	.flush_cache	= fib4_rule_flush_cache,
323 	.nlgroup	= RTNLGRP_IPV4_RULE,
324 	.policy		= fib4_rule_policy,
325 	.owner		= THIS_MODULE,
326 };
327 
328 static int fib_default_rules_init(struct fib_rules_ops *ops)
329 {
330 	int err;
331 
332 	err = fib_default_rule_add(ops, 0, RT_TABLE_LOCAL, 0);
333 	if (err < 0)
334 		return err;
335 	err = fib_default_rule_add(ops, 0x7FFE, RT_TABLE_MAIN, 0);
336 	if (err < 0)
337 		return err;
338 	err = fib_default_rule_add(ops, 0x7FFF, RT_TABLE_DEFAULT, 0);
339 	if (err < 0)
340 		return err;
341 	return 0;
342 }
343 
344 int __net_init fib4_rules_init(struct net *net)
345 {
346 	int err;
347 	struct fib_rules_ops *ops;
348 
349 	ops = fib_rules_register(&fib4_rules_ops_template, net);
350 	if (IS_ERR(ops))
351 		return PTR_ERR(ops);
352 
353 	err = fib_default_rules_init(ops);
354 	if (err < 0)
355 		goto fail;
356 	net->ipv4.rules_ops = ops;
357 	net->ipv4.fib_has_custom_rules = false;
358 	return 0;
359 
360 fail:
361 	/* also cleans all rules already added */
362 	fib_rules_unregister(ops);
363 	return err;
364 }
365 
366 void __net_exit fib4_rules_exit(struct net *net)
367 {
368 	fib_rules_unregister(net->ipv4.rules_ops);
369 }
370