xref: /linux/net/ipv6/fib6_rules.c (revision e5c86679d5e864947a52fb31e45a425dea3e7fa9) 
1 /*
2  * net/ipv6/fib6_rules.c	IPv6 Routing Policy Rules
3  *
4  * Copyright (C)2003-2006 Helsinki University of Technology
5  * Copyright (C)2003-2006 USAGI/WIDE Project
6  *
7  *	This program is free software; you can redistribute it and/or
8  *	modify it under the terms of the GNU General Public License as
9  *	published by the Free Software Foundation, version 2.
10  *
11  * Authors
12  *	Thomas Graf		<tgraf@suug.ch>
13  *	Ville Nuorvala		<vnuorval@tcs.hut.fi>
14  */
15 
16 #include <linux/netdevice.h>
17 #include <linux/export.h>
18 
19 #include <net/fib_rules.h>
20 #include <net/ipv6.h>
21 #include <net/addrconf.h>
22 #include <net/ip6_route.h>
23 #include <net/netlink.h>
24 
25 struct fib6_rule {
26 	struct fib_rule		common;
27 	struct rt6key		src;
28 	struct rt6key		dst;
29 	u8			tclass;
30 };
31 
32 struct dst_entry *fib6_rule_lookup(struct net *net, struct flowi6 *fl6,
33 				   int flags, pol_lookup_t lookup)
34 {
35 	struct rt6_info *rt;
36 	struct fib_lookup_arg arg = {
37 		.lookup_ptr = lookup,
38 		.flags = FIB_LOOKUP_NOREF,
39 	};
40 
41 	/* update flow if oif or iif point to device enslaved to l3mdev */
42 	l3mdev_update_flow(net, flowi6_to_flowi(fl6));
43 
44 	fib_rules_lookup(net->ipv6.fib6_rules_ops,
45 			 flowi6_to_flowi(fl6), flags, &arg);
46 
47 	rt = arg.result;
48 
49 	if (!rt) {
50 		dst_hold(&net->ipv6.ip6_null_entry->dst);
51 		return &net->ipv6.ip6_null_entry->dst;
52 	}
53 
54 	if (rt->rt6i_flags & RTF_REJECT &&
55 	    rt->dst.error == -EAGAIN) {
56 		ip6_rt_put(rt);
57 		rt = net->ipv6.ip6_null_entry;
58 		dst_hold(&rt->dst);
59 	}
60 
61 	return &rt->dst;
62 }
63 
64 static int fib6_rule_action(struct fib_rule *rule, struct flowi *flp,
65 			    int flags, struct fib_lookup_arg *arg)
66 {
67 	struct flowi6 *flp6 = &flp->u.ip6;
68 	struct rt6_info *rt = NULL;
69 	struct fib6_table *table;
70 	struct net *net = rule->fr_net;
71 	pol_lookup_t lookup = arg->lookup_ptr;
72 	int err = 0;
73 	u32 tb_id;
74 
75 	switch (rule->action) {
76 	case FR_ACT_TO_TBL:
77 		break;
78 	case FR_ACT_UNREACHABLE:
79 		err = -ENETUNREACH;
80 		rt = net->ipv6.ip6_null_entry;
81 		goto discard_pkt;
82 	default:
83 	case FR_ACT_BLACKHOLE:
84 		err = -EINVAL;
85 		rt = net->ipv6.ip6_blk_hole_entry;
86 		goto discard_pkt;
87 	case FR_ACT_PROHIBIT:
88 		err = -EACCES;
89 		rt = net->ipv6.ip6_prohibit_entry;
90 		goto discard_pkt;
91 	}
92 
93 	tb_id = fib_rule_get_table(rule, arg);
94 	table = fib6_get_table(net, tb_id);
95 	if (!table) {
96 		err = -EAGAIN;
97 		goto out;
98 	}
99 
100 	rt = lookup(net, table, flp6, flags);
101 	if (rt != net->ipv6.ip6_null_entry) {
102 		struct fib6_rule *r = (struct fib6_rule *)rule;
103 
104 		/*
105 		 * If we need to find a source address for this traffic,
106 		 * we check the result if it meets requirement of the rule.
107 		 */
108 		if ((rule->flags & FIB_RULE_FIND_SADDR) &&
109 		    r->src.plen && !(flags & RT6_LOOKUP_F_HAS_SADDR)) {
110 			struct in6_addr saddr;
111 
112 			if (ipv6_dev_get_saddr(net,
113 					       ip6_dst_idev(&rt->dst)->dev,
114 					       &flp6->daddr,
115 					       rt6_flags2srcprefs(flags),
116 					       &saddr))
117 				goto again;
118 			if (!ipv6_prefix_equal(&saddr, &r->src.addr,
119 					       r->src.plen))
120 				goto again;
121 			flp6->saddr = saddr;
122 		}
123 		err = rt->dst.error;
124 		goto out;
125 	}
126 again:
127 	ip6_rt_put(rt);
128 	err = -EAGAIN;
129 	rt = NULL;
130 	goto out;
131 
132 discard_pkt:
133 	dst_hold(&rt->dst);
134 out:
135 	arg->result = rt;
136 	return err;
137 }
138 
139 static bool fib6_rule_suppress(struct fib_rule *rule, struct fib_lookup_arg *arg)
140 {
141 	struct rt6_info *rt = (struct rt6_info *) arg->result;
142 	struct net_device *dev = NULL;
143 
144 	if (rt->rt6i_idev)
145 		dev = rt->rt6i_idev->dev;
146 
147 	/* do not accept result if the route does
148 	 * not meet the required prefix length
149 	 */
150 	if (rt->rt6i_dst.plen <= rule->suppress_prefixlen)
151 		goto suppress_route;
152 
153 	/* do not accept result if the route uses a device
154 	 * belonging to a forbidden interface group
155 	 */
156 	if (rule->suppress_ifgroup != -1 && dev && dev->group == rule->suppress_ifgroup)
157 		goto suppress_route;
158 
159 	return false;
160 
161 suppress_route:
162 	ip6_rt_put(rt);
163 	return true;
164 }
165 
166 static int fib6_rule_match(struct fib_rule *rule, struct flowi *fl, int flags)
167 {
168 	struct fib6_rule *r = (struct fib6_rule *) rule;
169 	struct flowi6 *fl6 = &fl->u.ip6;
170 
171 	if (r->dst.plen &&
172 	    !ipv6_prefix_equal(&fl6->daddr, &r->dst.addr, r->dst.plen))
173 		return 0;
174 
175 	/*
176 	 * If FIB_RULE_FIND_SADDR is set and we do not have a
177 	 * source address for the traffic, we defer check for
178 	 * source address.
179 	 */
180 	if (r->src.plen) {
181 		if (flags & RT6_LOOKUP_F_HAS_SADDR) {
182 			if (!ipv6_prefix_equal(&fl6->saddr, &r->src.addr,
183 					       r->src.plen))
184 				return 0;
185 		} else if (!(r->common.flags & FIB_RULE_FIND_SADDR))
186 			return 0;
187 	}
188 
189 	if (r->tclass && r->tclass != ip6_tclass(fl6->flowlabel))
190 		return 0;
191 
192 	return 1;
193 }
194 
195 static const struct nla_policy fib6_rule_policy[FRA_MAX+1] = {
196 	FRA_GENERIC_POLICY,
197 };
198 
199 static int fib6_rule_configure(struct fib_rule *rule, struct sk_buff *skb,
200 			       struct fib_rule_hdr *frh,
201 			       struct nlattr **tb)
202 {
203 	int err = -EINVAL;
204 	struct net *net = sock_net(skb->sk);
205 	struct fib6_rule *rule6 = (struct fib6_rule *) rule;
206 
207 	if (rule->action == FR_ACT_TO_TBL && !rule->l3mdev) {
208 		if (rule->table == RT6_TABLE_UNSPEC)
209 			goto errout;
210 
211 		if (fib6_new_table(net, rule->table) == NULL) {
212 			err = -ENOBUFS;
213 			goto errout;
214 		}
215 	}
216 
217 	if (frh->src_len)
218 		rule6->src.addr = nla_get_in6_addr(tb[FRA_SRC]);
219 
220 	if (frh->dst_len)
221 		rule6->dst.addr = nla_get_in6_addr(tb[FRA_DST]);
222 
223 	rule6->src.plen = frh->src_len;
224 	rule6->dst.plen = frh->dst_len;
225 	rule6->tclass = frh->tos;
226 
227 	err = 0;
228 errout:
229 	return err;
230 }
231 
232 static int fib6_rule_compare(struct fib_rule *rule, struct fib_rule_hdr *frh,
233 			     struct nlattr **tb)
234 {
235 	struct fib6_rule *rule6 = (struct fib6_rule *) rule;
236 
237 	if (frh->src_len && (rule6->src.plen != frh->src_len))
238 		return 0;
239 
240 	if (frh->dst_len && (rule6->dst.plen != frh->dst_len))
241 		return 0;
242 
243 	if (frh->tos && (rule6->tclass != frh->tos))
244 		return 0;
245 
246 	if (frh->src_len &&
247 	    nla_memcmp(tb[FRA_SRC], &rule6->src.addr, sizeof(struct in6_addr)))
248 		return 0;
249 
250 	if (frh->dst_len &&
251 	    nla_memcmp(tb[FRA_DST], &rule6->dst.addr, sizeof(struct in6_addr)))
252 		return 0;
253 
254 	return 1;
255 }
256 
257 static int fib6_rule_fill(struct fib_rule *rule, struct sk_buff *skb,
258 			  struct fib_rule_hdr *frh)
259 {
260 	struct fib6_rule *rule6 = (struct fib6_rule *) rule;
261 
262 	frh->dst_len = rule6->dst.plen;
263 	frh->src_len = rule6->src.plen;
264 	frh->tos = rule6->tclass;
265 
266 	if ((rule6->dst.plen &&
267 	     nla_put_in6_addr(skb, FRA_DST, &rule6->dst.addr)) ||
268 	    (rule6->src.plen &&
269 	     nla_put_in6_addr(skb, FRA_SRC, &rule6->src.addr)))
270 		goto nla_put_failure;
271 	return 0;
272 
273 nla_put_failure:
274 	return -ENOBUFS;
275 }
276 
277 static size_t fib6_rule_nlmsg_payload(struct fib_rule *rule)
278 {
279 	return nla_total_size(16) /* dst */
280 	       + nla_total_size(16); /* src */
281 }
282 
283 static const struct fib_rules_ops __net_initconst fib6_rules_ops_template = {
284 	.family			= AF_INET6,
285 	.rule_size		= sizeof(struct fib6_rule),
286 	.addr_size		= sizeof(struct in6_addr),
287 	.action			= fib6_rule_action,
288 	.match			= fib6_rule_match,
289 	.suppress		= fib6_rule_suppress,
290 	.configure		= fib6_rule_configure,
291 	.compare		= fib6_rule_compare,
292 	.fill			= fib6_rule_fill,
293 	.nlmsg_payload		= fib6_rule_nlmsg_payload,
294 	.nlgroup		= RTNLGRP_IPV6_RULE,
295 	.policy			= fib6_rule_policy,
296 	.owner			= THIS_MODULE,
297 	.fro_net		= &init_net,
298 };
299 
300 static int __net_init fib6_rules_net_init(struct net *net)
301 {
302 	struct fib_rules_ops *ops;
303 	int err = -ENOMEM;
304 
305 	ops = fib_rules_register(&fib6_rules_ops_template, net);
306 	if (IS_ERR(ops))
307 		return PTR_ERR(ops);
308 
309 	err = fib_default_rule_add(ops, 0, RT6_TABLE_LOCAL, 0);
310 	if (err)
311 		goto out_fib6_rules_ops;
312 
313 	err = fib_default_rule_add(ops, 0x7FFE, RT6_TABLE_MAIN, 0);
314 	if (err)
315 		goto out_fib6_rules_ops;
316 
317 	net->ipv6.fib6_rules_ops = ops;
318 out:
319 	return err;
320 
321 out_fib6_rules_ops:
322 	fib_rules_unregister(ops);
323 	goto out;
324 }
325 
326 static void __net_exit fib6_rules_net_exit(struct net *net)
327 {
328 	rtnl_lock();
329 	fib_rules_unregister(net->ipv6.fib6_rules_ops);
330 	rtnl_unlock();
331 }
332 
333 static struct pernet_operations fib6_rules_net_ops = {
334 	.init = fib6_rules_net_init,
335 	.exit = fib6_rules_net_exit,
336 };
337 
338 int __init fib6_rules_init(void)
339 {
340 	return register_pernet_subsys(&fib6_rules_net_ops);
341 }
342 
343 
344 void fib6_rules_cleanup(void)
345 {
346 	unregister_pernet_subsys(&fib6_rules_net_ops);
347 }
348