fib_rules.c revision 49dd18ba4615eaa72f15c9087dea1c2ab4744cf5 
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
36struct 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
50int __fib_lookup(struct net *net, struct flowi4 *flp, struct fib_result *res)
51{
52	struct fib_lookup_arg arg = {
53		.result = res,
54		.flags = FIB_LOOKUP_NOREF,
55	};
56	int err;
57
58	err = fib_rules_lookup(net->ipv4.rules_ops, flowi4_to_flowi(flp), 0, &arg);
59#ifdef CONFIG_IP_ROUTE_CLASSID
60	if (arg.rule)
61		res->tclassid = ((struct fib4_rule *)arg.rule)->tclassid;
62	else
63		res->tclassid = 0;
64#endif
65
66	if (err == -ESRCH)
67		err = -ENETUNREACH;
68
69	return err;
70}
71EXPORT_SYMBOL_GPL(__fib_lookup);
72
73static int fib4_rule_action(struct fib_rule *rule, struct flowi *flp,
74			    int flags, struct fib_lookup_arg *arg)
75{
76	int err = -EAGAIN;
77	struct fib_table *tbl;
78
79	switch (rule->action) {
80	case FR_ACT_TO_TBL:
81		break;
82
83	case FR_ACT_UNREACHABLE:
84		err = -ENETUNREACH;
85		goto errout;
86
87	case FR_ACT_PROHIBIT:
88		err = -EACCES;
89		goto errout;
90
91	case FR_ACT_BLACKHOLE:
92	default:
93		err = -EINVAL;
94		goto errout;
95	}
96
97	tbl = fib_get_table(rule->fr_net, rule->table);
98	if (!tbl)
99		goto errout;
100
101	err = fib_table_lookup(tbl, &flp->u.ip4, (struct fib_result *) arg->result, arg->flags);
102	if (err > 0)
103		err = -EAGAIN;
104errout:
105	return err;
106}
107
108static bool fib4_rule_suppress(struct fib_rule *rule, struct fib_lookup_arg *arg)
109{
110	struct fib_result *result = (struct fib_result *) arg->result;
111	struct net_device *dev = NULL;
112
113	if (result->fi)
114		dev = result->fi->fib_dev;
115
116	/* do not accept result if the route does
117	 * not meet the required prefix length
118	 */
119	if (result->prefixlen <= rule->suppress_prefixlen)
120		goto suppress_route;
121
122	/* do not accept result if the route uses a device
123	 * belonging to a forbidden interface group
124	 */
125	if (rule->suppress_ifgroup != -1 && dev && dev->group == rule->suppress_ifgroup)
126		goto suppress_route;
127
128	return false;
129
130suppress_route:
131	if (!(arg->flags & FIB_LOOKUP_NOREF))
132		fib_info_put(result->fi);
133	return true;
134}
135
136static int fib4_rule_match(struct fib_rule *rule, struct flowi *fl, int flags)
137{
138	struct fib4_rule *r = (struct fib4_rule *) rule;
139	struct flowi4 *fl4 = &fl->u.ip4;
140	__be32 daddr = fl4->daddr;
141	__be32 saddr = fl4->saddr;
142
143	if (((saddr ^ r->src) & r->srcmask) ||
144	    ((daddr ^ r->dst) & r->dstmask))
145		return 0;
146
147	if (r->tos && (r->tos != fl4->flowi4_tos))
148		return 0;
149
150	return 1;
151}
152
153static struct fib_table *fib_empty_table(struct net *net)
154{
155	u32 id;
156
157	for (id = 1; id <= RT_TABLE_MAX; id++)
158		if (fib_get_table(net, id) == NULL)
159			return fib_new_table(net, id);
160	return NULL;
161}
162
163static const struct nla_policy fib4_rule_policy[FRA_MAX+1] = {
164	FRA_GENERIC_POLICY,
165	[FRA_FLOW]	= { .type = NLA_U32 },
166};
167
168static int fib4_rule_configure(struct fib_rule *rule, struct sk_buff *skb,
169			       struct fib_rule_hdr *frh,
170			       struct nlattr **tb)
171{
172	struct net *net = sock_net(skb->sk);
173	int err = -EINVAL;
174	struct fib4_rule *rule4 = (struct fib4_rule *) rule;
175
176	if (frh->tos & ~IPTOS_TOS_MASK)
177		goto errout;
178
179	if (rule->table == RT_TABLE_UNSPEC) {
180		if (rule->action == FR_ACT_TO_TBL) {
181			struct fib_table *table;
182
183			table = fib_empty_table(net);
184			if (table == NULL) {
185				err = -ENOBUFS;
186				goto errout;
187			}
188
189			rule->table = table->tb_id;
190		}
191	}
192
193	if (frh->src_len)
194		rule4->src = nla_get_be32(tb[FRA_SRC]);
195
196	if (frh->dst_len)
197		rule4->dst = nla_get_be32(tb[FRA_DST]);
198
199#ifdef CONFIG_IP_ROUTE_CLASSID
200	if (tb[FRA_FLOW]) {
201		rule4->tclassid = nla_get_u32(tb[FRA_FLOW]);
202		if (rule4->tclassid)
203			net->ipv4.fib_num_tclassid_users++;
204	}
205#endif
206
207	rule4->src_len = frh->src_len;
208	rule4->srcmask = inet_make_mask(rule4->src_len);
209	rule4->dst_len = frh->dst_len;
210	rule4->dstmask = inet_make_mask(rule4->dst_len);
211	rule4->tos = frh->tos;
212
213	net->ipv4.fib_has_custom_rules = true;
214	err = 0;
215errout:
216	return err;
217}
218
219static void fib4_rule_delete(struct fib_rule *rule)
220{
221	struct net *net = rule->fr_net;
222#ifdef CONFIG_IP_ROUTE_CLASSID
223	struct fib4_rule *rule4 = (struct fib4_rule *) rule;
224
225	if (rule4->tclassid)
226		net->ipv4.fib_num_tclassid_users--;
227#endif
228	net->ipv4.fib_has_custom_rules = true;
229}
230
231static int fib4_rule_compare(struct fib_rule *rule, struct fib_rule_hdr *frh,
232			     struct nlattr **tb)
233{
234	struct fib4_rule *rule4 = (struct fib4_rule *) rule;
235
236	if (frh->src_len && (rule4->src_len != frh->src_len))
237		return 0;
238
239	if (frh->dst_len && (rule4->dst_len != frh->dst_len))
240		return 0;
241
242	if (frh->tos && (rule4->tos != frh->tos))
243		return 0;
244
245#ifdef CONFIG_IP_ROUTE_CLASSID
246	if (tb[FRA_FLOW] && (rule4->tclassid != nla_get_u32(tb[FRA_FLOW])))
247		return 0;
248#endif
249
250	if (frh->src_len && (rule4->src != nla_get_be32(tb[FRA_SRC])))
251		return 0;
252
253	if (frh->dst_len && (rule4->dst != nla_get_be32(tb[FRA_DST])))
254		return 0;
255
256	return 1;
257}
258
259static int fib4_rule_fill(struct fib_rule *rule, struct sk_buff *skb,
260			  struct fib_rule_hdr *frh)
261{
262	struct fib4_rule *rule4 = (struct fib4_rule *) rule;
263
264	frh->dst_len = rule4->dst_len;
265	frh->src_len = rule4->src_len;
266	frh->tos = rule4->tos;
267
268	if ((rule4->dst_len &&
269	     nla_put_be32(skb, FRA_DST, rule4->dst)) ||
270	    (rule4->src_len &&
271	     nla_put_be32(skb, FRA_SRC, rule4->src)))
272		goto nla_put_failure;
273#ifdef CONFIG_IP_ROUTE_CLASSID
274	if (rule4->tclassid &&
275	    nla_put_u32(skb, FRA_FLOW, rule4->tclassid))
276		goto nla_put_failure;
277#endif
278	return 0;
279
280nla_put_failure:
281	return -ENOBUFS;
282}
283
284static size_t fib4_rule_nlmsg_payload(struct fib_rule *rule)
285{
286	return nla_total_size(4) /* dst */
287	       + nla_total_size(4) /* src */
288	       + nla_total_size(4); /* flow */
289}
290
291static void fib4_rule_flush_cache(struct fib_rules_ops *ops)
292{
293	rt_cache_flush(ops->fro_net);
294}
295
296static const struct fib_rules_ops __net_initconst fib4_rules_ops_template = {
297	.family		= AF_INET,
298	.rule_size	= sizeof(struct fib4_rule),
299	.addr_size	= sizeof(u32),
300	.action		= fib4_rule_action,
301	.suppress	= fib4_rule_suppress,
302	.match		= fib4_rule_match,
303	.configure	= fib4_rule_configure,
304	.delete		= fib4_rule_delete,
305	.compare	= fib4_rule_compare,
306	.fill		= fib4_rule_fill,
307	.default_pref	= fib_default_rule_pref,
308	.nlmsg_payload	= fib4_rule_nlmsg_payload,
309	.flush_cache	= fib4_rule_flush_cache,
310	.nlgroup	= RTNLGRP_IPV4_RULE,
311	.policy		= fib4_rule_policy,
312	.owner		= THIS_MODULE,
313};
314
315static int fib_default_rules_init(struct fib_rules_ops *ops)
316{
317	int err;
318
319	err = fib_default_rule_add(ops, 0, RT_TABLE_LOCAL, 0);
320	if (err < 0)
321		return err;
322	err = fib_default_rule_add(ops, 0x7FFE, RT_TABLE_MAIN, 0);
323	if (err < 0)
324		return err;
325	err = fib_default_rule_add(ops, 0x7FFF, RT_TABLE_DEFAULT, 0);
326	if (err < 0)
327		return err;
328	return 0;
329}
330
331int __net_init fib4_rules_init(struct net *net)
332{
333	int err;
334	struct fib_rules_ops *ops;
335
336	ops = fib_rules_register(&fib4_rules_ops_template, net);
337	if (IS_ERR(ops))
338		return PTR_ERR(ops);
339
340	err = fib_default_rules_init(ops);
341	if (err < 0)
342		goto fail;
343	net->ipv4.rules_ops = ops;
344	net->ipv4.fib_has_custom_rules = false;
345	return 0;
346
347fail:
348	/* also cleans all rules already added */
349	fib_rules_unregister(ops);
350	return err;
351}
352
353void __net_exit fib4_rules_exit(struct net *net)
354{
355	fib_rules_unregister(net->ipv4.rules_ops);
356}
357