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 <net/ip.h>
30#include <net/route.h>
31#include <net/tcp.h>
32#include <net/ip_fib.h>
33#include <net/fib_rules.h>
34
35static struct fib_rules_ops fib4_rules_ops;
36
37struct fib4_rule
38{
39	struct fib_rule		common;
40	u8			dst_len;
41	u8			src_len;
42	u8			tos;
43	__be32			src;
44	__be32			srcmask;
45	__be32			dst;
46	__be32			dstmask;
47#ifdef CONFIG_NET_CLS_ROUTE
48	u32			tclassid;
49#endif
50};
51
52static struct fib4_rule default_rule = {
53	.common = {
54		.refcnt =	ATOMIC_INIT(2),
55		.pref =		0x7FFF,
56		.table =	RT_TABLE_DEFAULT,
57		.action =	FR_ACT_TO_TBL,
58	},
59};
60
61static struct fib4_rule main_rule = {
62	.common = {
63		.refcnt =	ATOMIC_INIT(2),
64		.pref =		0x7FFE,
65		.table =	RT_TABLE_MAIN,
66		.action =	FR_ACT_TO_TBL,
67	},
68};
69
70static struct fib4_rule local_rule = {
71	.common = {
72		.refcnt =	ATOMIC_INIT(2),
73		.table =	RT_TABLE_LOCAL,
74		.action =	FR_ACT_TO_TBL,
75		.flags =	FIB_RULE_PERMANENT,
76	},
77};
78
79static LIST_HEAD(fib4_rules);
80
81#ifdef CONFIG_NET_CLS_ROUTE
82u32 fib_rules_tclass(struct fib_result *res)
83{
84	return res->r ? ((struct fib4_rule *) res->r)->tclassid : 0;
85}
86#endif
87
88int fib_lookup(struct flowi *flp, struct fib_result *res)
89{
90	struct fib_lookup_arg arg = {
91		.result = res,
92	};
93	int err;
94
95	err = fib_rules_lookup(&fib4_rules_ops, flp, 0, &arg);
96	res->r = arg.rule;
97
98	return err;
99}
100
101static int fib4_rule_action(struct fib_rule *rule, struct flowi *flp,
102			    int flags, struct fib_lookup_arg *arg)
103{
104	int err = -EAGAIN;
105	struct fib_table *tbl;
106
107	switch (rule->action) {
108	case FR_ACT_TO_TBL:
109		break;
110
111	case FR_ACT_UNREACHABLE:
112		err = -ENETUNREACH;
113		goto errout;
114
115	case FR_ACT_PROHIBIT:
116		err = -EACCES;
117		goto errout;
118
119	case FR_ACT_BLACKHOLE:
120	default:
121		err = -EINVAL;
122		goto errout;
123	}
124
125	if ((tbl = fib_get_table(rule->table)) == NULL)
126		goto errout;
127
128	err = tbl->tb_lookup(tbl, flp, (struct fib_result *) arg->result);
129	if (err > 0)
130		err = -EAGAIN;
131errout:
132	return err;
133}
134
135
136void fib_select_default(const struct flowi *flp, struct fib_result *res)
137{
138	if (res->r && res->r->action == FR_ACT_TO_TBL &&
139	    FIB_RES_GW(*res) && FIB_RES_NH(*res).nh_scope == RT_SCOPE_LINK) {
140		struct fib_table *tb;
141		if ((tb = fib_get_table(res->r->table)) != NULL)
142			tb->tb_select_default(tb, flp, res);
143	}
144}
145
146static int fib4_rule_match(struct fib_rule *rule, struct flowi *fl, int flags)
147{
148	struct fib4_rule *r = (struct fib4_rule *) rule;
149	__be32 daddr = fl->fl4_dst;
150	__be32 saddr = fl->fl4_src;
151
152	if (((saddr ^ r->src) & r->srcmask) ||
153	    ((daddr ^ r->dst) & r->dstmask))
154		return 0;
155
156	if (r->tos && (r->tos != fl->fl4_tos))
157		return 0;
158
159	return 1;
160}
161
162static struct fib_table *fib_empty_table(void)
163{
164	u32 id;
165
166	for (id = 1; id <= RT_TABLE_MAX; id++)
167		if (fib_get_table(id) == NULL)
168			return fib_new_table(id);
169	return NULL;
170}
171
172static const struct nla_policy fib4_rule_policy[FRA_MAX+1] = {
173	FRA_GENERIC_POLICY,
174	[FRA_FLOW]	= { .type = NLA_U32 },
175};
176
177static int fib4_rule_configure(struct fib_rule *rule, struct sk_buff *skb,
178			       struct nlmsghdr *nlh, struct fib_rule_hdr *frh,
179			       struct nlattr **tb)
180{
181	int err = -EINVAL;
182	struct fib4_rule *rule4 = (struct fib4_rule *) rule;
183
184	if (frh->tos & ~IPTOS_TOS_MASK)
185		goto errout;
186
187	if (rule->table == RT_TABLE_UNSPEC) {
188		if (rule->action == FR_ACT_TO_TBL) {
189			struct fib_table *table;
190
191			table = fib_empty_table();
192			if (table == NULL) {
193				err = -ENOBUFS;
194				goto errout;
195			}
196
197			rule->table = table->tb_id;
198		}
199	}
200
201	if (frh->src_len)
202		rule4->src = nla_get_be32(tb[FRA_SRC]);
203
204	if (frh->dst_len)
205		rule4->dst = nla_get_be32(tb[FRA_DST]);
206
207#ifdef CONFIG_NET_CLS_ROUTE
208	if (tb[FRA_FLOW])
209		rule4->tclassid = nla_get_u32(tb[FRA_FLOW]);
210#endif
211
212	rule4->src_len = frh->src_len;
213	rule4->srcmask = inet_make_mask(rule4->src_len);
214	rule4->dst_len = frh->dst_len;
215	rule4->dstmask = inet_make_mask(rule4->dst_len);
216	rule4->tos = frh->tos;
217
218	err = 0;
219errout:
220	return err;
221}
222
223static int fib4_rule_compare(struct fib_rule *rule, struct fib_rule_hdr *frh,
224			     struct nlattr **tb)
225{
226	struct fib4_rule *rule4 = (struct fib4_rule *) rule;
227
228	if (frh->src_len && (rule4->src_len != frh->src_len))
229		return 0;
230
231	if (frh->dst_len && (rule4->dst_len != frh->dst_len))
232		return 0;
233
234	if (frh->tos && (rule4->tos != frh->tos))
235		return 0;
236
237#ifdef CONFIG_NET_CLS_ROUTE
238	if (tb[FRA_FLOW] && (rule4->tclassid != nla_get_u32(tb[FRA_FLOW])))
239		return 0;
240#endif
241
242	if (frh->src_len && (rule4->src != nla_get_be32(tb[FRA_SRC])))
243		return 0;
244
245	if (frh->dst_len && (rule4->dst != nla_get_be32(tb[FRA_DST])))
246		return 0;
247
248	return 1;
249}
250
251static int fib4_rule_fill(struct fib_rule *rule, struct sk_buff *skb,
252			  struct nlmsghdr *nlh, struct fib_rule_hdr *frh)
253{
254	struct fib4_rule *rule4 = (struct fib4_rule *) rule;
255
256	frh->family = AF_INET;
257	frh->dst_len = rule4->dst_len;
258	frh->src_len = rule4->src_len;
259	frh->tos = rule4->tos;
260
261	if (rule4->dst_len)
262		NLA_PUT_BE32(skb, FRA_DST, rule4->dst);
263
264	if (rule4->src_len)
265		NLA_PUT_BE32(skb, FRA_SRC, rule4->src);
266
267#ifdef CONFIG_NET_CLS_ROUTE
268	if (rule4->tclassid)
269		NLA_PUT_U32(skb, FRA_FLOW, rule4->tclassid);
270#endif
271	return 0;
272
273nla_put_failure:
274	return -ENOBUFS;
275}
276
277static u32 fib4_rule_default_pref(void)
278{
279	struct list_head *pos;
280	struct fib_rule *rule;
281
282	if (!list_empty(&fib4_rules)) {
283		pos = fib4_rules.next;
284		if (pos->next != &fib4_rules) {
285			rule = list_entry(pos->next, struct fib_rule, list);
286			if (rule->pref)
287				return rule->pref - 1;
288		}
289	}
290
291	return 0;
292}
293
294static size_t fib4_rule_nlmsg_payload(struct fib_rule *rule)
295{
296	return nla_total_size(4) /* dst */
297	       + nla_total_size(4) /* src */
298	       + nla_total_size(4); /* flow */
299}
300
301static void fib4_rule_flush_cache(void)
302{
303	rt_cache_flush(-1);
304}
305
306static struct fib_rules_ops fib4_rules_ops = {
307	.family		= AF_INET,
308	.rule_size	= sizeof(struct fib4_rule),
309	.addr_size	= sizeof(u32),
310	.action		= fib4_rule_action,
311	.match		= fib4_rule_match,
312	.configure	= fib4_rule_configure,
313	.compare	= fib4_rule_compare,
314	.fill		= fib4_rule_fill,
315	.default_pref	= fib4_rule_default_pref,
316	.nlmsg_payload	= fib4_rule_nlmsg_payload,
317	.flush_cache	= fib4_rule_flush_cache,
318	.nlgroup	= RTNLGRP_IPV4_RULE,
319	.policy		= fib4_rule_policy,
320	.rules_list	= &fib4_rules,
321	.owner		= THIS_MODULE,
322};
323
324void __init fib4_rules_init(void)
325{
326	list_add_tail(&local_rule.common.list, &fib4_rules);
327	list_add_tail(&main_rule.common.list, &fib4_rules);
328	list_add_tail(&default_rule.common.list, &fib4_rules);
329
330	fib_rules_register(&fib4_rules_ops);
331}
332