summaryrefslogtreecommitdiffstats
path: root/net/ipv4/fib_rules.c
blob: d531bc94b15ea23bb6f291388e83d06b0de50d8f (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
/*
 * INET		An implementation of the TCP/IP protocol suite for the LINUX
 *		operating system.  INET is implemented using the  BSD Socket
 *		interface as the means of communication with the user level.
 *
 *		IPv4 Forwarding Information Base: policy rules.
 *
 * Authors:	Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
 *		Thomas Graf <tgraf@suug.ch>
 *
 *		This program is free software; you can redistribute it and/or
 *		modify it under the terms of the GNU General Public License
 *		as published by the Free Software Foundation; either version
 *		2 of the License, or (at your option) any later version.
 *
 * Fixes:
 *		Rani Assaf	:	local_rule cannot be deleted
 *		Marc Boucher	:	routing by fwmark
 */

#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/netdevice.h>
#include <linux/netlink.h>
#include <linux/inetdevice.h>
#include <linux/init.h>
#include <linux/list.h>
#include <linux/rcupdate.h>
#include <linux/export.h>
#include <net/ip.h>
#include <net/route.h>
#include <net/tcp.h>
#include <net/ip_fib.h>
#include <net/fib_rules.h>

struct fib4_rule {
	struct fib_rule		common;
	u8			dst_len;
	u8			src_len;
	u8			tos;
	__be32			src;
	__be32			srcmask;
	__be32			dst;
	__be32			dstmask;
#ifdef CONFIG_IP_ROUTE_CLASSID
	u32			tclassid;
#endif
};

static bool fib4_rule_matchall(const struct fib_rule *rule)
{
	struct fib4_rule *r = container_of(rule, struct fib4_rule, common);

	if (r->dst_len || r->src_len || r->tos)
		return false;
	return fib_rule_matchall(rule);
}

bool fib4_rule_default(const struct fib_rule *rule)
{
	if (!fib4_rule_matchall(rule) || rule->action != FR_ACT_TO_TBL ||
	    rule->l3mdev)
		return false;
	if (rule->table != RT_TABLE_LOCAL && rule->table != RT_TABLE_MAIN &&
	    rule->table != RT_TABLE_DEFAULT)
		return false;
	return true;
}
EXPORT_SYMBOL_GPL(fib4_rule_default);

int __fib_lookup(struct net *net, struct flowi4 *flp,
		 struct fib_result *res, unsigned int flags)
{
	struct fib_lookup_arg arg = {
		.result = res,
		.flags = flags,
	};
	int err;

	/* update flow if oif or iif point to device enslaved to l3mdev */
	l3mdev_update_flow(net, flowi4_to_flowi(flp));

	err = fib_rules_lookup(net->ipv4.rules_ops, flowi4_to_flowi(flp), 0, &arg);
#ifdef CONFIG_IP_ROUTE_CLASSID
	if (arg.rule)
		res->tclassid = ((struct fib4_rule *)arg.rule)->tclassid;
	else
		res->tclassid = 0;
#endif

	if (err == -ESRCH)
		err = -ENETUNREACH;

	return err;
}
EXPORT_SYMBOL_GPL(__fib_lookup);

static int fib4_rule_action(struct fib_rule *rule, struct flowi *flp,
			    int flags, struct fib_lookup_arg *arg)
{
	int err = -EAGAIN;
	struct fib_table *tbl;
	u32 tb_id;

	switch (rule->action) {
	case FR_ACT_TO_TBL:
		break;

	case FR_ACT_UNREACHABLE:
		return -ENETUNREACH;

	case FR_ACT_PROHIBIT:
		return -EACCES;

	case FR_ACT_BLACKHOLE:
	default:
		return -EINVAL;
	}

	rcu_read_lock();

	tb_id = fib_rule_get_table(rule, arg);
	tbl = fib_get_table(rule->fr_net, tb_id);
	if (tbl)
		err = fib_table_lookup(tbl, &flp->u.ip4,
				       (struct fib_result *)arg->result,
				       arg->flags);

	rcu_read_unlock();
	return err;
}

static bool fib4_rule_suppress(struct fib_rule *rule, struct fib_lookup_arg *arg)
{
	struct fib_result *result = (struct fib_result *) arg->result;
	struct net_device *dev = NULL;

	if (result->fi)
		dev = result->fi->fib_dev;

	/* do not accept result if the route does
	 * not meet the required prefix length
	 */
	if (result->prefixlen <= rule->suppress_prefixlen)
		goto suppress_route;

	/* do not accept result if the route uses a device
	 * belonging to a forbidden interface group
	 */
	if (rule->suppress_ifgroup != -1 && dev && dev->group == rule->suppress_ifgroup)
		goto suppress_route;

	return false;

suppress_route:
	if (!(arg->flags & FIB_LOOKUP_NOREF))
		fib_info_put(result->fi);
	return true;
}

static int fib4_rule_match(struct fib_rule *rule, struct flowi *fl, int flags)
{
	struct fib4_rule *r = (struct fib4_rule *) rule;
	struct flowi4 *fl4 = &fl->u.ip4;
	__be32 daddr = fl4->daddr;
	__be32 saddr = fl4->saddr;

	if (((saddr ^ r->src) & r->srcmask) ||
	    ((daddr ^ r->dst) & r->dstmask))
		return 0;

	if (r->tos && (r->tos != fl4->flowi4_tos))
		return 0;

	return 1;
}

static struct fib_table *fib_empty_table(struct net *net)
{
	u32 id;

	for (id = 1; id <= RT_TABLE_MAX; id++)
		if (!fib_get_table(net, id))
			return fib_new_table(net, id);
	return NULL;
}

static int call_fib_rule_notifiers(struct net *net,
				   enum fib_event_type event_type)
{
	struct fib_notifier_info info;

	return call_fib_notifiers(net, event_type, &info);
}

void fib_rules_notify(struct net *net, struct notifier_block *nb)
{
	struct fib_notifier_info info;

	if (net->ipv4.fib_has_custom_rules)
		call_fib_notifier(nb, net, FIB_EVENT_RULE_ADD, &info);
}

static const struct nla_policy fib4_rule_policy[FRA_MAX+1] = {
	FRA_GENERIC_POLICY,
	[FRA_FLOW]	= { .type = NLA_U32 },
};

static int fib4_rule_configure(struct fib_rule *rule, struct sk_buff *skb,
			       struct fib_rule_hdr *frh,
			       struct nlattr **tb)
{
	struct net *net = sock_net(skb->sk);
	int err = -EINVAL;
	struct fib4_rule *rule4 = (struct fib4_rule *) rule;

	if (frh->tos & ~IPTOS_TOS_MASK)
		goto errout;

	/* split local/main if they are not already split */
	err = fib_unmerge(net);
	if (err)
		goto errout;

	if (rule->table == RT_TABLE_UNSPEC && !rule->l3mdev) {
		if (rule->action == FR_ACT_TO_TBL) {
			struct fib_table *table;

			table = fib_empty_table(net);
			if (!table) {
				err = -ENOBUFS;
				goto errout;
			}

			rule->table = table->tb_id;
		}
	}

	if (frh->src_len)
		rule4->src = nla_get_in_addr(tb[FRA_SRC]);

	if (frh->dst_len)
		rule4->dst = nla_get_in_addr(tb[FRA_DST]);

#ifdef CONFIG_IP_ROUTE_CLASSID
	if (tb[FRA_FLOW]) {
		rule4->tclassid = nla_get_u32(tb[FRA_FLOW]);
		if (rule4->tclassid)
			net->ipv4.fib_num_tclassid_users++;
	}
#endif

	rule4->src_len = frh->src_len;
	rule4->srcmask = inet_make_mask(rule4->src_len);
	rule4->dst_len = frh->dst_len;
	rule4->dstmask = inet_make_mask(rule4->dst_len);
	rule4->tos = frh->tos;

	net->ipv4.fib_has_custom_rules = true;
	call_fib_rule_notifiers(net, FIB_EVENT_RULE_ADD);

	err = 0;
errout:
	return err;
}

static int fib4_rule_delete(struct fib_rule *rule)
{
	struct net *net = rule->fr_net;
	int err;

	/* split local/main if they are not already split */
	err = fib_unmerge(net);
	if (err)
		goto errout;

#ifdef CONFIG_IP_ROUTE_CLASSID
	if (((struct fib4_rule *)rule)->tclassid)
		net->ipv4.fib_num_tclassid_users--;
#endif
	net->ipv4.fib_has_custom_rules = true;
	call_fib_rule_notifiers(net, FIB_EVENT_RULE_DEL);
errout:
	return err;
}

static int fib4_rule_compare(struct fib_rule *rule, struct fib_rule_hdr *frh,
			     struct nlattr **tb)
{
	struct fib4_rule *rule4 = (struct fib4_rule *) rule;

	if (frh->src_len && (rule4->src_len != frh->src_len))
		return 0;

	if (frh->dst_len && (rule4->dst_len != frh->dst_len))
		return 0;

	if (frh->tos && (rule4->tos != frh->tos))
		return 0;

#ifdef CONFIG_IP_ROUTE_CLASSID
	if (tb[FRA_FLOW] && (rule4->tclassid != nla_get_u32(tb[FRA_FLOW])))
		return 0;
#endif

	if (frh->src_len && (rule4->src != nla_get_in_addr(tb[FRA_SRC])))
		return 0;

	if (frh->dst_len && (rule4->dst != nla_get_in_addr(tb[FRA_DST])))
		return 0;

	return 1;
}

static int fib4_rule_fill(struct fib_rule *rule, struct sk_buff *skb,
			  struct fib_rule_hdr *frh)
{
	struct fib4_rule *rule4 = (struct fib4_rule *) rule;

	frh->dst_len = rule4->dst_len;
	frh->src_len = rule4->src_len;
	frh->tos = rule4->tos;

	if ((rule4->dst_len &&
	     nla_put_in_addr(skb, FRA_DST, rule4->dst)) ||
	    (rule4->src_len &&
	     nla_put_in_addr(skb, FRA_SRC, rule4->src)))
		goto nla_put_failure;
#ifdef CONFIG_IP_ROUTE_CLASSID
	if (rule4->tclassid &&
	    nla_put_u32(skb, FRA_FLOW, rule4->tclassid))
		goto nla_put_failure;
#endif
	return 0;

nla_put_failure:
	return -ENOBUFS;
}

static size_t fib4_rule_nlmsg_payload(struct fib_rule *rule)
{
	return nla_total_size(4) /* dst */
	       + nla_total_size(4) /* src */
	       + nla_total_size(4); /* flow */
}

static void fib4_rule_flush_cache(struct fib_rules_ops *ops)
{
	rt_cache_flush(ops->fro_net);
}

static const struct fib_rules_ops __net_initconst fib4_rules_ops_template = {
	.family		= AF_INET,
	.rule_size	= sizeof(struct fib4_rule),
	.addr_size	= sizeof(u32),
	.action		= fib4_rule_action,
	.suppress	= fib4_rule_suppress,
	.match		= fib4_rule_match,
	.configure	= fib4_rule_configure,
	.delete		= fib4_rule_delete,
	.compare	= fib4_rule_compare,
	.fill		= fib4_rule_fill,
	.nlmsg_payload	= fib4_rule_nlmsg_payload,
	.flush_cache	= fib4_rule_flush_cache,
	.nlgroup	= RTNLGRP_IPV4_RULE,
	.policy		= fib4_rule_policy,
	.owner		= THIS_MODULE,
};

static int fib_default_rules_init(struct fib_rules_ops *ops)
{
	int err;

	err = fib_default_rule_add(ops, 0, RT_TABLE_LOCAL, 0);
	if (err < 0)
		return err;
	err = fib_default_rule_add(ops, 0x7FFE, RT_TABLE_MAIN, 0);
	if (err < 0)
		return err;
	err = fib_default_rule_add(ops, 0x7FFF, RT_TABLE_DEFAULT, 0);
	if (err < 0)
		return err;
	return 0;
}

int __net_init fib4_rules_init(struct net *net)
{
	int err;
	struct fib_rules_ops *ops;

	ops = fib_rules_register(&fib4_rules_ops_template, net);
	if (IS_ERR(ops))
		return PTR_ERR(ops);

	err = fib_default_rules_init(ops);
	if (err < 0)
		goto fail;
	net->ipv4.rules_ops = ops;
	net->ipv4.fib_has_custom_rules = false;
	return 0;

fail:
	/* also cleans all rules already added */
	fib_rules_unregister(ops);
	return err;
}

void __net_exit fib4_rules_exit(struct net *net)
{
	fib_rules_unregister(net->ipv4.rules_ops);
}