xref: /linux/net/ipv6/fib6_rules.c (revision a8cb826aeab84553a30af22ca6d6b95a6513adb2) 
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 	fib_rules_lookup(net->ipv6.fib6_rules_ops,
42 			 flowi6_to_flowi(fl6), flags, &arg);
43 
44 	rt = arg.result;
45 
46 	if (!rt) {
47 		dst_hold(&net->ipv6.ip6_null_entry->dst);
48 		return &net->ipv6.ip6_null_entry->dst;
49 	}
50 
51 	if (rt->rt6i_flags & RTF_REJECT &&
52 	    rt->dst.error == -EAGAIN) {
53 		ip6_rt_put(rt);
54 		rt = net->ipv6.ip6_null_entry;
55 		dst_hold(&rt->dst);
56 	}
57 
58 	return &rt->dst;
59 }
60 
61 static int fib6_rule_action(struct fib_rule *rule, struct flowi *flp,
62 			    int flags, struct fib_lookup_arg *arg)
63 {
64 	struct flowi6 *flp6 = &flp->u.ip6;
65 	struct rt6_info *rt = NULL;
66 	struct fib6_table *table;
67 	struct net *net = rule->fr_net;
68 	pol_lookup_t lookup = arg->lookup_ptr;
69 	int err = 0;
70 
71 	switch (rule->action) {
72 	case FR_ACT_TO_TBL:
73 		break;
74 	case FR_ACT_UNREACHABLE:
75 		err = -ENETUNREACH;
76 		rt = net->ipv6.ip6_null_entry;
77 		goto discard_pkt;
78 	default:
79 	case FR_ACT_BLACKHOLE:
80 		err = -EINVAL;
81 		rt = net->ipv6.ip6_blk_hole_entry;
82 		goto discard_pkt;
83 	case FR_ACT_PROHIBIT:
84 		err = -EACCES;
85 		rt = net->ipv6.ip6_prohibit_entry;
86 		goto discard_pkt;
87 	}
88 
89 	table = fib6_get_table(net, rule->table);
90 	if (!table) {
91 		err = -EAGAIN;
92 		goto out;
93 	}
94 
95 	rt = lookup(net, table, flp6, flags);
96 	if (rt != net->ipv6.ip6_null_entry) {
97 		struct fib6_rule *r = (struct fib6_rule *)rule;
98 
99 		/*
100 		 * If we need to find a source address for this traffic,
101 		 * we check the result if it meets requirement of the rule.
102 		 */
103 		if ((rule->flags & FIB_RULE_FIND_SADDR) &&
104 		    r->src.plen && !(flags & RT6_LOOKUP_F_HAS_SADDR)) {
105 			struct in6_addr saddr;
106 
107 			if (ipv6_dev_get_saddr(net,
108 					       ip6_dst_idev(&rt->dst)->dev,
109 					       &flp6->daddr,
110 					       rt6_flags2srcprefs(flags),
111 					       &saddr))
112 				goto again;
113 			if (!ipv6_prefix_equal(&saddr, &r->src.addr,
114 					       r->src.plen))
115 				goto again;
116 			flp6->saddr = saddr;
117 		}
118 		err = rt->dst.error;
119 		goto out;
120 	}
121 again:
122 	ip6_rt_put(rt);
123 	err = -EAGAIN;
124 	rt = NULL;
125 	goto out;
126 
127 discard_pkt:
128 	dst_hold(&rt->dst);
129 out:
130 	arg->result = rt;
131 	return err;
132 }
133 
134 static bool fib6_rule_suppress(struct fib_rule *rule, struct fib_lookup_arg *arg)
135 {
136 	struct rt6_info *rt = (struct rt6_info *) arg->result;
137 	struct net_device *dev = NULL;
138 
139 	if (rt->rt6i_idev)
140 		dev = rt->rt6i_idev->dev;
141 
142 	/* do not accept result if the route does
143 	 * not meet the required prefix length
144 	 */
145 	if (rt->rt6i_dst.plen <= rule->suppress_prefixlen)
146 		goto suppress_route;
147 
148 	/* do not accept result if the route uses a device
149 	 * belonging to a forbidden interface group
150 	 */
151 	if (rule->suppress_ifgroup != -1 && dev && dev->group == rule->suppress_ifgroup)
152 		goto suppress_route;
153 
154 	return false;
155 
156 suppress_route:
157 	ip6_rt_put(rt);
158 	return true;
159 }
160 
161 static int fib6_rule_match(struct fib_rule *rule, struct flowi *fl, int flags)
162 {
163 	struct fib6_rule *r = (struct fib6_rule *) rule;
164 	struct flowi6 *fl6 = &fl->u.ip6;
165 
166 	if (r->dst.plen &&
167 	    !ipv6_prefix_equal(&fl6->daddr, &r->dst.addr, r->dst.plen))
168 		return 0;
169 
170 	/*
171 	 * If FIB_RULE_FIND_SADDR is set and we do not have a
172 	 * source address for the traffic, we defer check for
173 	 * source address.
174 	 */
175 	if (r->src.plen) {
176 		if (flags & RT6_LOOKUP_F_HAS_SADDR) {
177 			if (!ipv6_prefix_equal(&fl6->saddr, &r->src.addr,
178 					       r->src.plen))
179 				return 0;
180 		} else if (!(r->common.flags & FIB_RULE_FIND_SADDR))
181 			return 0;
182 	}
183 
184 	if (r->tclass && r->tclass != ip6_tclass(fl6->flowlabel))
185 		return 0;
186 
187 	return 1;
188 }
189 
190 static const struct nla_policy fib6_rule_policy[FRA_MAX+1] = {
191 	FRA_GENERIC_POLICY,
192 };
193 
194 static int fib6_rule_configure(struct fib_rule *rule, struct sk_buff *skb,
195 			       struct fib_rule_hdr *frh,
196 			       struct nlattr **tb)
197 {
198 	int err = -EINVAL;
199 	struct net *net = sock_net(skb->sk);
200 	struct fib6_rule *rule6 = (struct fib6_rule *) rule;
201 
202 	if (rule->action == FR_ACT_TO_TBL) {
203 		if (rule->table == RT6_TABLE_UNSPEC)
204 			goto errout;
205 
206 		if (fib6_new_table(net, rule->table) == NULL) {
207 			err = -ENOBUFS;
208 			goto errout;
209 		}
210 	}
211 
212 	if (frh->src_len)
213 		rule6->src.addr = nla_get_in6_addr(tb[FRA_SRC]);
214 
215 	if (frh->dst_len)
216 		rule6->dst.addr = nla_get_in6_addr(tb[FRA_DST]);
217 
218 	rule6->src.plen = frh->src_len;
219 	rule6->dst.plen = frh->dst_len;
220 	rule6->tclass = frh->tos;
221 
222 	err = 0;
223 errout:
224 	return err;
225 }
226 
227 static int fib6_rule_compare(struct fib_rule *rule, struct fib_rule_hdr *frh,
228 			     struct nlattr **tb)
229 {
230 	struct fib6_rule *rule6 = (struct fib6_rule *) rule;
231 
232 	if (frh->src_len && (rule6->src.plen != frh->src_len))
233 		return 0;
234 
235 	if (frh->dst_len && (rule6->dst.plen != frh->dst_len))
236 		return 0;
237 
238 	if (frh->tos && (rule6->tclass != frh->tos))
239 		return 0;
240 
241 	if (frh->src_len &&
242 	    nla_memcmp(tb[FRA_SRC], &rule6->src.addr, sizeof(struct in6_addr)))
243 		return 0;
244 
245 	if (frh->dst_len &&
246 	    nla_memcmp(tb[FRA_DST], &rule6->dst.addr, sizeof(struct in6_addr)))
247 		return 0;
248 
249 	return 1;
250 }
251 
252 static int fib6_rule_fill(struct fib_rule *rule, struct sk_buff *skb,
253 			  struct fib_rule_hdr *frh)
254 {
255 	struct fib6_rule *rule6 = (struct fib6_rule *) rule;
256 
257 	frh->dst_len = rule6->dst.plen;
258 	frh->src_len = rule6->src.plen;
259 	frh->tos = rule6->tclass;
260 
261 	if ((rule6->dst.plen &&
262 	     nla_put_in6_addr(skb, FRA_DST, &rule6->dst.addr)) ||
263 	    (rule6->src.plen &&
264 	     nla_put_in6_addr(skb, FRA_SRC, &rule6->src.addr)))
265 		goto nla_put_failure;
266 	return 0;
267 
268 nla_put_failure:
269 	return -ENOBUFS;
270 }
271 
272 static size_t fib6_rule_nlmsg_payload(struct fib_rule *rule)
273 {
274 	return nla_total_size(16) /* dst */
275 	       + nla_total_size(16); /* src */
276 }
277 
278 static const struct fib_rules_ops __net_initconst fib6_rules_ops_template = {
279 	.family			= AF_INET6,
280 	.rule_size		= sizeof(struct fib6_rule),
281 	.addr_size		= sizeof(struct in6_addr),
282 	.action			= fib6_rule_action,
283 	.match			= fib6_rule_match,
284 	.suppress		= fib6_rule_suppress,
285 	.configure		= fib6_rule_configure,
286 	.compare		= fib6_rule_compare,
287 	.fill			= fib6_rule_fill,
288 	.nlmsg_payload		= fib6_rule_nlmsg_payload,
289 	.nlgroup		= RTNLGRP_IPV6_RULE,
290 	.policy			= fib6_rule_policy,
291 	.owner			= THIS_MODULE,
292 	.fro_net		= &init_net,
293 };
294 
295 static int __net_init fib6_rules_net_init(struct net *net)
296 {
297 	struct fib_rules_ops *ops;
298 	int err = -ENOMEM;
299 
300 	ops = fib_rules_register(&fib6_rules_ops_template, net);
301 	if (IS_ERR(ops))
302 		return PTR_ERR(ops);
303 
304 	err = fib_default_rule_add(ops, 0, RT6_TABLE_LOCAL, 0);
305 	if (err)
306 		goto out_fib6_rules_ops;
307 
308 	err = fib_default_rule_add(ops, 0x7FFE, RT6_TABLE_MAIN, 0);
309 	if (err)
310 		goto out_fib6_rules_ops;
311 
312 	net->ipv6.fib6_rules_ops = ops;
313 out:
314 	return err;
315 
316 out_fib6_rules_ops:
317 	fib_rules_unregister(ops);
318 	goto out;
319 }
320 
321 static void __net_exit fib6_rules_net_exit(struct net *net)
322 {
323 	rtnl_lock();
324 	fib_rules_unregister(net->ipv6.fib6_rules_ops);
325 	rtnl_unlock();
326 }
327 
328 static struct pernet_operations fib6_rules_net_ops = {
329 	.init = fib6_rules_net_init,
330 	.exit = fib6_rules_net_exit,
331 };
332 
333 int __init fib6_rules_init(void)
334 {
335 	return register_pernet_subsys(&fib6_rules_net_ops);
336 }
337 
338 
339 void fib6_rules_cleanup(void)
340 {
341 	unregister_pernet_subsys(&fib6_rules_net_ops);
342 }
343