aboutsummaryrefslogtreecommitdiff
path: root/security/selinux/netif.c
blob: 326f22cbe405d745912965a11bd7c6babb28e7b6 (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
/*
 * Network interface table.
 *
 * Network interfaces (devices) do not have a security field, so we
 * maintain a table associating each interface with a SID.
 *
 * Author: James Morris <jmorris@redhat.com>
 *
 * Copyright (C) 2003 Red Hat, Inc., James Morris <jmorris@redhat.com>
 * Copyright (C) 2007 Hewlett-Packard Development Company, L.P.
 *		      Paul Moore <paul@paul-moore.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2,
 * as published by the Free Software Foundation.
 */
#include <linux/init.h>
#include <linux/types.h>
#include <linux/slab.h>
#include <linux/stddef.h>
#include <linux/kernel.h>
#include <linux/list.h>
#include <linux/notifier.h>
#include <linux/netdevice.h>
#include <linux/rcupdate.h>
#include <net/net_namespace.h>

#include "security.h"
#include "objsec.h"
#include "netif.h"

#define SEL_NETIF_HASH_SIZE	64
#define SEL_NETIF_HASH_MAX	1024

struct sel_netif {
	struct list_head list;
	struct netif_security_struct nsec;
	struct rcu_head rcu_head;
};

static u32 sel_netif_total;
static LIST_HEAD(sel_netif_list);
static DEFINE_SPINLOCK(sel_netif_lock);
static struct list_head sel_netif_hash[SEL_NETIF_HASH_SIZE];

/**
 * sel_netif_hashfn - Hashing function for the interface table
 * @ifindex: the network interface
 *
 * Description:
 * This is the hashing function for the network interface table, it returns the
 * bucket number for the given interface.
 *
 */
static inline u32 sel_netif_hashfn(int ifindex)
{
	return (ifindex & (SEL_NETIF_HASH_SIZE - 1));
}

/**
 * sel_netif_find - Search for an interface record
 * @ifindex: the network interface
 *
 * Description:
 * Search the network interface table and return the record matching @ifindex.
 * If an entry can not be found in the table return NULL.
 *
 */
static inline struct sel_netif *sel_netif_find(int ifindex)
{
	int idx = sel_netif_hashfn(ifindex);
	struct sel_netif *netif;

	list_for_each_entry_rcu(netif, &sel_netif_hash[idx], list)
		/* all of the devices should normally fit in the hash, so we
		 * optimize for that case */
		if (likely(netif->nsec.ifindex == ifindex))
			return netif;

	return NULL;
}

/**
 * sel_netif_insert - Insert a new interface into the table
 * @netif: the new interface record
 *
 * Description:
 * Add a new interface record to the network interface hash table.  Returns
 * zero on success, negative values on failure.
 *
 */
static int sel_netif_insert(struct sel_netif *netif)
{
	int idx;

	if (sel_netif_total >= SEL_NETIF_HASH_MAX)
		return -ENOSPC;

	idx = sel_netif_hashfn(netif->nsec.ifindex);
	list_add_rcu(&netif->list, &sel_netif_hash[idx]);
	sel_netif_total++;

	return 0;
}

/**
 * sel_netif_destroy - Remove an interface record from the table
 * @netif: the existing interface record
 *
 * Description:
 * Remove an existing interface record from the network interface table.
 *
 */
static void sel_netif_destroy(struct sel_netif *netif)
{
	list_del_rcu(&netif->list);
	sel_netif_total--;
	kfree_rcu(netif, rcu_head);
}

/**
 * sel_netif_sid_slow - Lookup the SID of a network interface using the policy
 * @ifindex: the network interface
 * @sid: interface SID
 *
 * Description:
 * This function determines the SID of a network interface by quering the
 * security policy.  The result is added to the network interface table to
 * speedup future queries.  Returns zero on success, negative values on
 * failure.
 *
 */
static int sel_netif_sid_slow(int ifindex, u32 *sid)
{
	int ret;
	struct sel_netif *netif;
	struct sel_netif *new = NULL;
	struct net_device *dev;

	/* NOTE: we always use init's network namespace since we don't
	 * currently support containers */

	dev = dev_get_by_index(&init_net, ifindex);
	if (unlikely(dev == NULL)) {
		printk(KERN_WARNING
		       "SELinux: failure in sel_netif_sid_slow(),"
		       " invalid network interface (%d)\n", ifindex);
		return -ENOENT;
	}

	spin_lock_bh(&sel_netif_lock);
	netif = sel_netif_find(ifindex);
	if (netif != NULL) {
		*sid = netif->nsec.sid;
		ret = 0;
		goto out;
	}
	new = kzalloc(sizeof(*new), GFP_ATOMIC);
	if (new == NULL) {
		ret = -ENOMEM;
		goto out;
	}
	ret = security_netif_sid(dev->name, &new->nsec.sid);
	if (ret != 0)
		goto out;
	new->nsec.ifindex = ifindex;
	ret = sel_netif_insert(new);
	if (ret != 0)
		goto out;
	*sid = new->nsec.sid;

out:
	spin_unlock_bh(&sel_netif_lock);
	dev_put(dev);
	if (unlikely(ret)) {
		printk(KERN_WARNING
		       "SELinux: failure in sel_netif_sid_slow(),"
		       " unable to determine network interface label (%d)\n",
		       ifindex);
		kfree(new);
	}
	return ret;
}

/**
 * sel_netif_sid - Lookup the SID of a network interface
 * @ifindex: the network interface
 * @sid: interface SID
 *
 * Description:
 * This function determines the SID of a network interface using the fastest
 * method possible.  First the interface table is queried, but if an entry
 * can't be found then the policy is queried and the result is added to the
 * table to speedup future queries.  Returns zero on success, negative values
 * on failure.
 *
 */
int sel_netif_sid(int ifindex, u32 *sid)
{
	struct sel_netif *netif;

	rcu_read_lock();
	netif = sel_netif_find(ifindex);
	if (likely(netif != NULL)) {
		*sid = netif->nsec.sid;
		rcu_read_unlock();
		return 0;
	}
	rcu_read_unlock();

	return sel_netif_sid_slow(ifindex, sid);
}

/**
 * sel_netif_kill - Remove an entry from the network interface table
 * @ifindex: the network interface
 *
 * Description:
 * This function removes the entry matching @ifindex from the network interface
 * table if it exists.
 *
 */
static void sel_netif_kill(int ifindex)
{
	struct sel_netif *netif;

	rcu_read_lock();
	spin_lock_bh(&sel_netif_lock);
	netif = sel_netif_find(ifindex);
	if (netif)
		sel_netif_destroy(netif);
	spin_unlock_bh(&sel_netif_lock);
	rcu_read_unlock();
}

/**
 * sel_netif_flush - Flush the entire network interface table
 *
 * Description:
 * Remove all entries from the network interface table.
 *
 */
static void sel_netif_flush(void)
{
	int idx;
	struct sel_netif *netif;

	spin_lock_bh(&sel_netif_lock);
	for (idx = 0; idx < SEL_NETIF_HASH_SIZE; idx++)
		list_for_each_entry(netif, &sel_netif_hash[idx], list)
			sel_netif_destroy(netif);
	spin_unlock_bh(&sel_netif_lock);
}

static int sel_netif_avc_callback(u32 event, u32 ssid, u32 tsid,
				  u16 class, u32 perms, u32 *retained)
{
	if (event == AVC_CALLBACK_RESET) {
		sel_netif_flush();
		synchronize_net();
	}
	return 0;
}

static int sel_netif_netdev_notifier_handler(struct notifier_block *this,
					     unsigned long event, void *ptr)
{
	struct net_device *dev = ptr;

	if (dev_net(dev) != &init_net)
		return NOTIFY_DONE;

	if (event == NETDEV_DOWN)
		sel_netif_kill(dev->ifindex);

	return NOTIFY_DONE;
}

static struct notifier_block sel_netif_netdev_notifier = {
	.notifier_call = sel_netif_netdev_notifier_handler,
};

static __init int sel_netif_init(void)
{
	int i, err;

	if (!selinux_enabled)
		return 0;

	for (i = 0; i < SEL_NETIF_HASH_SIZE; i++)
		INIT_LIST_HEAD(&sel_netif_hash[i]);

	register_netdevice_notifier(&sel_netif_netdev_notifier);

	err = avc_add_callback(sel_netif_avc_callback, AVC_CALLBACK_RESET,
			       SECSID_NULL, SECSID_NULL, SECCLASS_NULL, 0);
	if (err)
		panic("avc_add_callback() failed, error %d\n", err);

	return err;
}

__initcall(sel_netif_init);