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
25struct fib6_rule {
26	struct fib_rule		common;
27	struct rt6key		src;
28	struct rt6key		dst;
29	u8			tclass;
30};
31
32struct dst_entry *fib6_rule_lookup(struct net *net, struct flowi6 *fl6,
33				   int flags, pol_lookup_t lookup)
34{
35	struct fib_lookup_arg arg = {
36		.lookup_ptr = lookup,
37		.flags = FIB_LOOKUP_NOREF,
38	};
39
40	fib_rules_lookup(net->ipv6.fib6_rules_ops,
41			 flowi6_to_flowi(fl6), flags, &arg);
42
43	if (arg.result)
44		return arg.result;
45
46	dst_hold(&net->ipv6.ip6_null_entry->dst);
47	return &net->ipv6.ip6_null_entry->dst;
48}
49
50static int fib6_rule_action(struct fib_rule *rule, struct flowi *flp,
51			    int flags, struct fib_lookup_arg *arg)
52{
53	struct flowi6 *flp6 = &flp->u.ip6;
54	struct rt6_info *rt = NULL;
55	struct fib6_table *table;
56	struct net *net = rule->fr_net;
57	pol_lookup_t lookup = arg->lookup_ptr;
58	int err = 0;
59
60	switch (rule->action) {
61	case FR_ACT_TO_TBL:
62		break;
63	case FR_ACT_UNREACHABLE:
64		err = -ENETUNREACH;
65		rt = net->ipv6.ip6_null_entry;
66		goto discard_pkt;
67	default:
68	case FR_ACT_BLACKHOLE:
69		err = -EINVAL;
70		rt = net->ipv6.ip6_blk_hole_entry;
71		goto discard_pkt;
72	case FR_ACT_PROHIBIT:
73		err = -EACCES;
74		rt = net->ipv6.ip6_prohibit_entry;
75		goto discard_pkt;
76	}
77
78	table = fib6_get_table(net, rule->table);
79	if (!table) {
80		err = -EAGAIN;
81		goto out;
82	}
83
84	rt = lookup(net, table, flp6, flags);
85	if (rt != net->ipv6.ip6_null_entry) {
86		struct fib6_rule *r = (struct fib6_rule *)rule;
87
88		/*
89		 * If we need to find a source address for this traffic,
90		 * we check the result if it meets requirement of the rule.
91		 */
92		if ((rule->flags & FIB_RULE_FIND_SADDR) &&
93		    r->src.plen && !(flags & RT6_LOOKUP_F_HAS_SADDR)) {
94			struct in6_addr saddr;
95
96			if (ipv6_dev_get_saddr(net,
97					       ip6_dst_idev(&rt->dst)->dev,
98					       &flp6->daddr,
99					       rt6_flags2srcprefs(flags),
100					       &saddr))
101				goto again;
102			if (!ipv6_prefix_equal(&saddr, &r->src.addr,
103					       r->src.plen))
104				goto again;
105			flp6->saddr = saddr;
106		}
107		err = rt->dst.error;
108		goto out;
109	}
110again:
111	ip6_rt_put(rt);
112	err = -EAGAIN;
113	rt = NULL;
114	goto out;
115
116discard_pkt:
117	dst_hold(&rt->dst);
118out:
119	arg->result = rt;
120	return err;
121}
122
123static bool fib6_rule_suppress(struct fib_rule *rule, struct fib_lookup_arg *arg)
124{
125	struct rt6_info *rt = (struct rt6_info *) arg->result;
126	struct net_device *dev = NULL;
127
128	if (rt->rt6i_idev)
129		dev = rt->rt6i_idev->dev;
130
131	/* do not accept result if the route does
132	 * not meet the required prefix length
133	 */
134	if (rt->rt6i_dst.plen <= rule->suppress_prefixlen)
135		goto suppress_route;
136
137	/* do not accept result if the route uses a device
138	 * belonging to a forbidden interface group
139	 */
140	if (rule->suppress_ifgroup != -1 && dev && dev->group == rule->suppress_ifgroup)
141		goto suppress_route;
142
143	return false;
144
145suppress_route:
146	ip6_rt_put(rt);
147	return true;
148}
149
150static int fib6_rule_match(struct fib_rule *rule, struct flowi *fl, int flags)
151{
152	struct fib6_rule *r = (struct fib6_rule *) rule;
153	struct flowi6 *fl6 = &fl->u.ip6;
154
155	if (r->dst.plen &&
156	    !ipv6_prefix_equal(&fl6->daddr, &r->dst.addr, r->dst.plen))
157		return 0;
158
159	/*
160	 * If FIB_RULE_FIND_SADDR is set and we do not have a
161	 * source address for the traffic, we defer check for
162	 * source address.
163	 */
164	if (r->src.plen) {
165		if (flags & RT6_LOOKUP_F_HAS_SADDR) {
166			if (!ipv6_prefix_equal(&fl6->saddr, &r->src.addr,
167					       r->src.plen))
168				return 0;
169		} else if (!(r->common.flags & FIB_RULE_FIND_SADDR))
170			return 0;
171	}
172
173	if (r->tclass && r->tclass != ip6_tclass(fl6->flowlabel))
174		return 0;
175
176	return 1;
177}
178
179static const struct nla_policy fib6_rule_policy[FRA_MAX+1] = {
180	FRA_GENERIC_POLICY,
181};
182
183static int fib6_rule_configure(struct fib_rule *rule, struct sk_buff *skb,
184			       struct fib_rule_hdr *frh,
185			       struct nlattr **tb)
186{
187	int err = -EINVAL;
188	struct net *net = sock_net(skb->sk);
189	struct fib6_rule *rule6 = (struct fib6_rule *) rule;
190
191	if (rule->action == FR_ACT_TO_TBL) {
192		if (rule->table == RT6_TABLE_UNSPEC)
193			goto errout;
194
195		if (fib6_new_table(net, rule->table) == NULL) {
196			err = -ENOBUFS;
197			goto errout;
198		}
199	}
200
201	if (frh->src_len)
202		rule6->src.addr = nla_get_in6_addr(tb[FRA_SRC]);
203
204	if (frh->dst_len)
205		rule6->dst.addr = nla_get_in6_addr(tb[FRA_DST]);
206
207	rule6->src.plen = frh->src_len;
208	rule6->dst.plen = frh->dst_len;
209	rule6->tclass = frh->tos;
210
211	err = 0;
212errout:
213	return err;
214}
215
216static int fib6_rule_compare(struct fib_rule *rule, struct fib_rule_hdr *frh,
217			     struct nlattr **tb)
218{
219	struct fib6_rule *rule6 = (struct fib6_rule *) rule;
220
221	if (frh->src_len && (rule6->src.plen != frh->src_len))
222		return 0;
223
224	if (frh->dst_len && (rule6->dst.plen != frh->dst_len))
225		return 0;
226
227	if (frh->tos && (rule6->tclass != frh->tos))
228		return 0;
229
230	if (frh->src_len &&
231	    nla_memcmp(tb[FRA_SRC], &rule6->src.addr, sizeof(struct in6_addr)))
232		return 0;
233
234	if (frh->dst_len &&
235	    nla_memcmp(tb[FRA_DST], &rule6->dst.addr, sizeof(struct in6_addr)))
236		return 0;
237
238	return 1;
239}
240
241static int fib6_rule_fill(struct fib_rule *rule, struct sk_buff *skb,
242			  struct fib_rule_hdr *frh)
243{
244	struct fib6_rule *rule6 = (struct fib6_rule *) rule;
245
246	frh->dst_len = rule6->dst.plen;
247	frh->src_len = rule6->src.plen;
248	frh->tos = rule6->tclass;
249
250	if ((rule6->dst.plen &&
251	     nla_put_in6_addr(skb, FRA_DST, &rule6->dst.addr)) ||
252	    (rule6->src.plen &&
253	     nla_put_in6_addr(skb, FRA_SRC, &rule6->src.addr)))
254		goto nla_put_failure;
255	return 0;
256
257nla_put_failure:
258	return -ENOBUFS;
259}
260
261static u32 fib6_rule_default_pref(struct fib_rules_ops *ops)
262{
263	return 0x3FFF;
264}
265
266static size_t fib6_rule_nlmsg_payload(struct fib_rule *rule)
267{
268	return nla_total_size(16) /* dst */
269	       + nla_total_size(16); /* src */
270}
271
272static const struct fib_rules_ops __net_initconst fib6_rules_ops_template = {
273	.family			= AF_INET6,
274	.rule_size		= sizeof(struct fib6_rule),
275	.addr_size		= sizeof(struct in6_addr),
276	.action			= fib6_rule_action,
277	.match			= fib6_rule_match,
278	.suppress		= fib6_rule_suppress,
279	.configure		= fib6_rule_configure,
280	.compare		= fib6_rule_compare,
281	.fill			= fib6_rule_fill,
282	.default_pref		= fib6_rule_default_pref,
283	.nlmsg_payload		= fib6_rule_nlmsg_payload,
284	.nlgroup		= RTNLGRP_IPV6_RULE,
285	.policy			= fib6_rule_policy,
286	.owner			= THIS_MODULE,
287	.fro_net		= &init_net,
288};
289
290static int __net_init fib6_rules_net_init(struct net *net)
291{
292	struct fib_rules_ops *ops;
293	int err = -ENOMEM;
294
295	ops = fib_rules_register(&fib6_rules_ops_template, net);
296	if (IS_ERR(ops))
297		return PTR_ERR(ops);
298
299	err = fib_default_rule_add(ops, 0, RT6_TABLE_LOCAL, 0);
300	if (err)
301		goto out_fib6_rules_ops;
302
303	err = fib_default_rule_add(ops, 0x7FFE, RT6_TABLE_MAIN, 0);
304	if (err)
305		goto out_fib6_rules_ops;
306
307	net->ipv6.fib6_rules_ops = ops;
308out:
309	return err;
310
311out_fib6_rules_ops:
312	fib_rules_unregister(ops);
313	goto out;
314}
315
316static void __net_exit fib6_rules_net_exit(struct net *net)
317{
318	rtnl_lock();
319	fib_rules_unregister(net->ipv6.fib6_rules_ops);
320	rtnl_unlock();
321}
322
323static struct pernet_operations fib6_rules_net_ops = {
324	.init = fib6_rules_net_init,
325	.exit = fib6_rules_net_exit,
326};
327
328int __init fib6_rules_init(void)
329{
330	return register_pernet_subsys(&fib6_rules_net_ops);
331}
332
333
334void fib6_rules_cleanup(void)
335{
336	unregister_pernet_subsys(&fib6_rules_net_ops);
337}
338