xref: /linux/net/ipv6/fib6_rules.c (revision 80483c3abf8423e6ec4fb63647a8e2e1f5976801) 
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 	u32 tb_id;
71 
72 	switch (rule->action) {
73 	case FR_ACT_TO_TBL:
74 		break;
75 	case FR_ACT_UNREACHABLE:
76 		err = -ENETUNREACH;
77 		rt = net->ipv6.ip6_null_entry;
78 		goto discard_pkt;
79 	default:
80 	case FR_ACT_BLACKHOLE:
81 		err = -EINVAL;
82 		rt = net->ipv6.ip6_blk_hole_entry;
83 		goto discard_pkt;
84 	case FR_ACT_PROHIBIT:
85 		err = -EACCES;
86 		rt = net->ipv6.ip6_prohibit_entry;
87 		goto discard_pkt;
88 	}
89 
90 	tb_id = fib_rule_get_table(rule, arg);
91 	table = fib6_get_table(net, tb_id);
92 	if (!table) {
93 		err = -EAGAIN;
94 		goto out;
95 	}
96 
97 	rt = lookup(net, table, flp6, flags);
98 	if (rt != net->ipv6.ip6_null_entry) {
99 		struct fib6_rule *r = (struct fib6_rule *)rule;
100 
101 		/*
102 		 * If we need to find a source address for this traffic,
103 		 * we check the result if it meets requirement of the rule.
104 		 */
105 		if ((rule->flags & FIB_RULE_FIND_SADDR) &&
106 		    r->src.plen && !(flags & RT6_LOOKUP_F_HAS_SADDR)) {
107 			struct in6_addr saddr;
108 
109 			if (ipv6_dev_get_saddr(net,
110 					       ip6_dst_idev(&rt->dst)->dev,
111 					       &flp6->daddr,
112 					       rt6_flags2srcprefs(flags),
113 					       &saddr))
114 				goto again;
115 			if (!ipv6_prefix_equal(&saddr, &r->src.addr,
116 					       r->src.plen))
117 				goto again;
118 			flp6->saddr = saddr;
119 		}
120 		err = rt->dst.error;
121 		goto out;
122 	}
123 again:
124 	ip6_rt_put(rt);
125 	err = -EAGAIN;
126 	rt = NULL;
127 	goto out;
128 
129 discard_pkt:
130 	dst_hold(&rt->dst);
131 out:
132 	arg->result = rt;
133 	return err;
134 }
135 
136 static bool fib6_rule_suppress(struct fib_rule *rule, struct fib_lookup_arg *arg)
137 {
138 	struct rt6_info *rt = (struct rt6_info *) arg->result;
139 	struct net_device *dev = NULL;
140 
141 	if (rt->rt6i_idev)
142 		dev = rt->rt6i_idev->dev;
143 
144 	/* do not accept result if the route does
145 	 * not meet the required prefix length
146 	 */
147 	if (rt->rt6i_dst.plen <= rule->suppress_prefixlen)
148 		goto suppress_route;
149 
150 	/* do not accept result if the route uses a device
151 	 * belonging to a forbidden interface group
152 	 */
153 	if (rule->suppress_ifgroup != -1 && dev && dev->group == rule->suppress_ifgroup)
154 		goto suppress_route;
155 
156 	return false;
157 
158 suppress_route:
159 	ip6_rt_put(rt);
160 	return true;
161 }
162 
163 static int fib6_rule_match(struct fib_rule *rule, struct flowi *fl, int flags)
164 {
165 	struct fib6_rule *r = (struct fib6_rule *) rule;
166 	struct flowi6 *fl6 = &fl->u.ip6;
167 
168 	if (r->dst.plen &&
169 	    !ipv6_prefix_equal(&fl6->daddr, &r->dst.addr, r->dst.plen))
170 		return 0;
171 
172 	/*
173 	 * If FIB_RULE_FIND_SADDR is set and we do not have a
174 	 * source address for the traffic, we defer check for
175 	 * source address.
176 	 */
177 	if (r->src.plen) {
178 		if (flags & RT6_LOOKUP_F_HAS_SADDR) {
179 			if (!ipv6_prefix_equal(&fl6->saddr, &r->src.addr,
180 					       r->src.plen))
181 				return 0;
182 		} else if (!(r->common.flags & FIB_RULE_FIND_SADDR))
183 			return 0;
184 	}
185 
186 	if (r->tclass && r->tclass != ip6_tclass(fl6->flowlabel))
187 		return 0;
188 
189 	return 1;
190 }
191 
192 static const struct nla_policy fib6_rule_policy[FRA_MAX+1] = {
193 	FRA_GENERIC_POLICY,
194 };
195 
196 static int fib6_rule_configure(struct fib_rule *rule, struct sk_buff *skb,
197 			       struct fib_rule_hdr *frh,
198 			       struct nlattr **tb)
199 {
200 	int err = -EINVAL;
201 	struct net *net = sock_net(skb->sk);
202 	struct fib6_rule *rule6 = (struct fib6_rule *) rule;
203 
204 	if (rule->action == FR_ACT_TO_TBL && !rule->l3mdev) {
205 		if (rule->table == RT6_TABLE_UNSPEC)
206 			goto errout;
207 
208 		if (fib6_new_table(net, rule->table) == NULL) {
209 			err = -ENOBUFS;
210 			goto errout;
211 		}
212 	}
213 
214 	if (frh->src_len)
215 		rule6->src.addr = nla_get_in6_addr(tb[FRA_SRC]);
216 
217 	if (frh->dst_len)
218 		rule6->dst.addr = nla_get_in6_addr(tb[FRA_DST]);
219 
220 	rule6->src.plen = frh->src_len;
221 	rule6->dst.plen = frh->dst_len;
222 	rule6->tclass = frh->tos;
223 
224 	err = 0;
225 errout:
226 	return err;
227 }
228 
229 static int fib6_rule_compare(struct fib_rule *rule, struct fib_rule_hdr *frh,
230 			     struct nlattr **tb)
231 {
232 	struct fib6_rule *rule6 = (struct fib6_rule *) rule;
233 
234 	if (frh->src_len && (rule6->src.plen != frh->src_len))
235 		return 0;
236 
237 	if (frh->dst_len && (rule6->dst.plen != frh->dst_len))
238 		return 0;
239 
240 	if (frh->tos && (rule6->tclass != frh->tos))
241 		return 0;
242 
243 	if (frh->src_len &&
244 	    nla_memcmp(tb[FRA_SRC], &rule6->src.addr, sizeof(struct in6_addr)))
245 		return 0;
246 
247 	if (frh->dst_len &&
248 	    nla_memcmp(tb[FRA_DST], &rule6->dst.addr, sizeof(struct in6_addr)))
249 		return 0;
250 
251 	return 1;
252 }
253 
254 static int fib6_rule_fill(struct fib_rule *rule, struct sk_buff *skb,
255 			  struct fib_rule_hdr *frh)
256 {
257 	struct fib6_rule *rule6 = (struct fib6_rule *) rule;
258 
259 	frh->dst_len = rule6->dst.plen;
260 	frh->src_len = rule6->src.plen;
261 	frh->tos = rule6->tclass;
262 
263 	if ((rule6->dst.plen &&
264 	     nla_put_in6_addr(skb, FRA_DST, &rule6->dst.addr)) ||
265 	    (rule6->src.plen &&
266 	     nla_put_in6_addr(skb, FRA_SRC, &rule6->src.addr)))
267 		goto nla_put_failure;
268 	return 0;
269 
270 nla_put_failure:
271 	return -ENOBUFS;
272 }
273 
274 static size_t fib6_rule_nlmsg_payload(struct fib_rule *rule)
275 {
276 	return nla_total_size(16) /* dst */
277 	       + nla_total_size(16); /* src */
278 }
279 
280 static const struct fib_rules_ops __net_initconst fib6_rules_ops_template = {
281 	.family			= AF_INET6,
282 	.rule_size		= sizeof(struct fib6_rule),
283 	.addr_size		= sizeof(struct in6_addr),
284 	.action			= fib6_rule_action,
285 	.match			= fib6_rule_match,
286 	.suppress		= fib6_rule_suppress,
287 	.configure		= fib6_rule_configure,
288 	.compare		= fib6_rule_compare,
289 	.fill			= fib6_rule_fill,
290 	.nlmsg_payload		= fib6_rule_nlmsg_payload,
291 	.nlgroup		= RTNLGRP_IPV6_RULE,
292 	.policy			= fib6_rule_policy,
293 	.owner			= THIS_MODULE,
294 	.fro_net		= &init_net,
295 };
296 
297 static int __net_init fib6_rules_net_init(struct net *net)
298 {
299 	struct fib_rules_ops *ops;
300 	int err = -ENOMEM;
301 
302 	ops = fib_rules_register(&fib6_rules_ops_template, net);
303 	if (IS_ERR(ops))
304 		return PTR_ERR(ops);
305 
306 	err = fib_default_rule_add(ops, 0, RT6_TABLE_LOCAL, 0);
307 	if (err)
308 		goto out_fib6_rules_ops;
309 
310 	err = fib_default_rule_add(ops, 0x7FFE, RT6_TABLE_MAIN, 0);
311 	if (err)
312 		goto out_fib6_rules_ops;
313 
314 	net->ipv6.fib6_rules_ops = ops;
315 out:
316 	return err;
317 
318 out_fib6_rules_ops:
319 	fib_rules_unregister(ops);
320 	goto out;
321 }
322 
323 static void __net_exit fib6_rules_net_exit(struct net *net)
324 {
325 	rtnl_lock();
326 	fib_rules_unregister(net->ipv6.fib6_rules_ops);
327 	rtnl_unlock();
328 }
329 
330 static struct pernet_operations fib6_rules_net_ops = {
331 	.init = fib6_rules_net_init,
332 	.exit = fib6_rules_net_exit,
333 };
334 
335 int __init fib6_rules_init(void)
336 {
337 	return register_pernet_subsys(&fib6_rules_net_ops);
338 }
339 
340 
341 void fib6_rules_cleanup(void)
342 {
343 	unregister_pernet_subsys(&fib6_rules_net_ops);
344 }
345