1/*
2 * Network interface table.
3 *
4 * Network interfaces (devices) do not have a security field, so we
5 * maintain a table associating each interface with a SID.
6 *
7 * Author: James Morris <jmorris@redhat.com>
8 *
9 * Copyright (C) 2003 Red Hat, Inc., James Morris <jmorris@redhat.com>
10 *
11 * This program is free software; you can redistribute it and/or modify
12 * it under the terms of the GNU General Public License version 2,
13 * as published by the Free Software Foundation.
14 */
15#include <linux/init.h>
16#include <linux/types.h>
17#include <linux/stddef.h>
18#include <linux/kernel.h>
19#include <linux/list.h>
20#include <linux/notifier.h>
21#include <linux/netdevice.h>
22#include <linux/rcupdate.h>
23
24#include "security.h"
25#include "objsec.h"
26#include "netif.h"
27
28#define SEL_NETIF_HASH_SIZE	64
29#define SEL_NETIF_HASH_MAX	1024
30
31#undef DEBUG
32
33#ifdef DEBUG
34#define DEBUGP printk
35#else
36#define DEBUGP(format, args...)
37#endif
38
39struct sel_netif
40{
41	struct list_head list;
42	struct netif_security_struct nsec;
43	struct rcu_head rcu_head;
44};
45
46static u32 sel_netif_total;
47static LIST_HEAD(sel_netif_list);
48static DEFINE_SPINLOCK(sel_netif_lock);
49static struct list_head sel_netif_hash[SEL_NETIF_HASH_SIZE];
50
51static inline u32 sel_netif_hasfn(struct net_device *dev)
52{
53	return (dev->ifindex & (SEL_NETIF_HASH_SIZE - 1));
54}
55
56/*
57 * All of the devices should normally fit in the hash, so we optimize
58 * for that case.
59 */
60static inline struct sel_netif *sel_netif_find(struct net_device *dev)
61{
62	struct list_head *pos;
63	int idx = sel_netif_hasfn(dev);
64
65	__list_for_each_rcu(pos, &sel_netif_hash[idx]) {
66		struct sel_netif *netif = list_entry(pos,
67		                                     struct sel_netif, list);
68		if (likely(netif->nsec.dev == dev))
69			return netif;
70	}
71	return NULL;
72}
73
74static int sel_netif_insert(struct sel_netif *netif)
75{
76	int idx, ret = 0;
77
78	if (sel_netif_total >= SEL_NETIF_HASH_MAX) {
79		ret = -ENOSPC;
80		goto out;
81	}
82
83	idx = sel_netif_hasfn(netif->nsec.dev);
84	list_add_rcu(&netif->list, &sel_netif_hash[idx]);
85	sel_netif_total++;
86out:
87	return ret;
88}
89
90static void sel_netif_free(struct rcu_head *p)
91{
92	struct sel_netif *netif = container_of(p, struct sel_netif, rcu_head);
93
94	DEBUGP("%s: %s\n", __FUNCTION__, netif->nsec.dev->name);
95	kfree(netif);
96}
97
98static void sel_netif_destroy(struct sel_netif *netif)
99{
100	DEBUGP("%s: %s\n", __FUNCTION__, netif->nsec.dev->name);
101
102	list_del_rcu(&netif->list);
103	sel_netif_total--;
104	call_rcu(&netif->rcu_head, sel_netif_free);
105}
106
107static struct sel_netif *sel_netif_lookup(struct net_device *dev)
108{
109	int ret;
110	struct sel_netif *netif, *new;
111	struct netif_security_struct *nsec;
112
113	netif = sel_netif_find(dev);
114	if (likely(netif != NULL))
115		goto out;
116
117	new = kzalloc(sizeof(*new), GFP_ATOMIC);
118	if (!new) {
119		netif = ERR_PTR(-ENOMEM);
120		goto out;
121	}
122
123	nsec = &new->nsec;
124
125	ret = security_netif_sid(dev->name, &nsec->if_sid, &nsec->msg_sid);
126	if (ret < 0) {
127		kfree(new);
128		netif = ERR_PTR(ret);
129		goto out;
130	}
131
132	nsec->dev = dev;
133
134	spin_lock_bh(&sel_netif_lock);
135
136	netif = sel_netif_find(dev);
137	if (netif) {
138		spin_unlock_bh(&sel_netif_lock);
139		kfree(new);
140		goto out;
141	}
142
143	ret = sel_netif_insert(new);
144	spin_unlock_bh(&sel_netif_lock);
145
146	if (ret) {
147		kfree(new);
148		netif = ERR_PTR(ret);
149		goto out;
150	}
151
152	netif = new;
153
154	DEBUGP("new: ifindex=%u name=%s if_sid=%u msg_sid=%u\n", dev->ifindex, dev->name,
155	        nsec->if_sid, nsec->msg_sid);
156out:
157	return netif;
158}
159
160static void sel_netif_assign_sids(u32 if_sid_in, u32 msg_sid_in, u32 *if_sid_out, u32 *msg_sid_out)
161{
162	if (if_sid_out)
163		*if_sid_out = if_sid_in;
164	if (msg_sid_out)
165		*msg_sid_out = msg_sid_in;
166}
167
168static int sel_netif_sids_slow(struct net_device *dev, u32 *if_sid, u32 *msg_sid)
169{
170	int ret = 0;
171	u32 tmp_if_sid, tmp_msg_sid;
172
173	ret = security_netif_sid(dev->name, &tmp_if_sid, &tmp_msg_sid);
174	if (!ret)
175		sel_netif_assign_sids(tmp_if_sid, tmp_msg_sid, if_sid, msg_sid);
176	return ret;
177}
178
179int sel_netif_sids(struct net_device *dev, u32 *if_sid, u32 *msg_sid)
180{
181	int ret = 0;
182	struct sel_netif *netif;
183
184	rcu_read_lock();
185	netif = sel_netif_lookup(dev);
186	if (IS_ERR(netif)) {
187		rcu_read_unlock();
188		ret = sel_netif_sids_slow(dev, if_sid, msg_sid);
189		goto out;
190	}
191	sel_netif_assign_sids(netif->nsec.if_sid, netif->nsec.msg_sid, if_sid, msg_sid);
192	rcu_read_unlock();
193out:
194	return ret;
195}
196
197static void sel_netif_kill(struct net_device *dev)
198{
199	struct sel_netif *netif;
200
201	spin_lock_bh(&sel_netif_lock);
202	netif = sel_netif_find(dev);
203	if (netif)
204		sel_netif_destroy(netif);
205	spin_unlock_bh(&sel_netif_lock);
206}
207
208static void sel_netif_flush(void)
209{
210	int idx;
211
212	spin_lock_bh(&sel_netif_lock);
213	for (idx = 0; idx < SEL_NETIF_HASH_SIZE; idx++) {
214		struct sel_netif *netif;
215
216		list_for_each_entry(netif, &sel_netif_hash[idx], list)
217			sel_netif_destroy(netif);
218	}
219	spin_unlock_bh(&sel_netif_lock);
220}
221
222static int sel_netif_avc_callback(u32 event, u32 ssid, u32 tsid,
223                                  u16 class, u32 perms, u32 *retained)
224{
225	if (event == AVC_CALLBACK_RESET) {
226		sel_netif_flush();
227		synchronize_net();
228	}
229	return 0;
230}
231
232static int sel_netif_netdev_notifier_handler(struct notifier_block *this,
233                                             unsigned long event, void *ptr)
234{
235	struct net_device *dev = ptr;
236
237	if (event == NETDEV_DOWN)
238		sel_netif_kill(dev);
239
240	return NOTIFY_DONE;
241}
242
243static struct notifier_block sel_netif_netdev_notifier = {
244	.notifier_call = sel_netif_netdev_notifier_handler,
245};
246
247static __init int sel_netif_init(void)
248{
249	int i, err = 0;
250
251	if (!selinux_enabled)
252		goto out;
253
254	for (i = 0; i < SEL_NETIF_HASH_SIZE; i++)
255		INIT_LIST_HEAD(&sel_netif_hash[i]);
256
257	register_netdevice_notifier(&sel_netif_netdev_notifier);
258
259	err = avc_add_callback(sel_netif_avc_callback, AVC_CALLBACK_RESET,
260	                       SECSID_NULL, SECSID_NULL, SECCLASS_NULL, 0);
261	if (err)
262		panic("avc_add_callback() failed, error %d\n", err);
263
264out:
265	return err;
266}
267
268__initcall(sel_netif_init);
269