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 * Copyright (C) 2007 Hewlett-Packard Development Company, L.P.
11 * Paul Moore <paul@paul-moore.com>
12 *
13 * This program is free software; you can redistribute it and/or modify
14 * it under the terms of the GNU General Public License version 2,
15 * as published by the Free Software Foundation.
16 */
17 #include <linux/init.h>
18 #include <linux/types.h>
19 #include <linux/slab.h>
20 #include <linux/stddef.h>
21 #include <linux/kernel.h>
22 #include <linux/list.h>
23 #include <linux/notifier.h>
24 #include <linux/netdevice.h>
25 #include <linux/rcupdate.h>
26 #include <net/net_namespace.h>
27
28 #include "security.h"
29 #include "objsec.h"
30 #include "netif.h"
31
32 #define SEL_NETIF_HASH_SIZE 64
33 #define SEL_NETIF_HASH_MAX 1024
34
35 struct sel_netif {
36 struct list_head list;
37 struct netif_security_struct nsec;
38 struct rcu_head rcu_head;
39 };
40
41 static u32 sel_netif_total;
42 static LIST_HEAD(sel_netif_list);
43 static DEFINE_SPINLOCK(sel_netif_lock);
44 static struct list_head sel_netif_hash[SEL_NETIF_HASH_SIZE];
45
46 /**
47 * sel_netif_hashfn - Hashing function for the interface table
48 * @ns: the network namespace
49 * @ifindex: the network interface
50 *
51 * Description:
52 * This is the hashing function for the network interface table, it returns the
53 * bucket number for the given interface.
54 *
55 */
sel_netif_hashfn(const struct net * ns,int ifindex)56 static inline u32 sel_netif_hashfn(const struct net *ns, int ifindex)
57 {
58 return (((uintptr_t)ns + ifindex) & (SEL_NETIF_HASH_SIZE - 1));
59 }
60
61 /**
62 * sel_netif_find - Search for an interface record
63 * @ns: the network namespace
64 * @ifindex: the network interface
65 *
66 * Description:
67 * Search the network interface table and return the record matching @ifindex.
68 * If an entry can not be found in the table return NULL.
69 *
70 */
sel_netif_find(const struct net * ns,int ifindex)71 static inline struct sel_netif *sel_netif_find(const struct net *ns,
72 int ifindex)
73 {
74 int idx = sel_netif_hashfn(ns, ifindex);
75 struct sel_netif *netif;
76
77 list_for_each_entry_rcu(netif, &sel_netif_hash[idx], list)
78 if (net_eq(netif->nsec.ns, ns) &&
79 netif->nsec.ifindex == ifindex)
80 return netif;
81
82 return NULL;
83 }
84
85 /**
86 * sel_netif_insert - Insert a new interface into the table
87 * @netif: the new interface record
88 *
89 * Description:
90 * Add a new interface record to the network interface hash table. Returns
91 * zero on success, negative values on failure.
92 *
93 */
sel_netif_insert(struct sel_netif * netif)94 static int sel_netif_insert(struct sel_netif *netif)
95 {
96 int idx;
97
98 if (sel_netif_total >= SEL_NETIF_HASH_MAX)
99 return -ENOSPC;
100
101 idx = sel_netif_hashfn(netif->nsec.ns, netif->nsec.ifindex);
102 list_add_rcu(&netif->list, &sel_netif_hash[idx]);
103 sel_netif_total++;
104
105 return 0;
106 }
107
108 /**
109 * sel_netif_destroy - Remove an interface record from the table
110 * @netif: the existing interface record
111 *
112 * Description:
113 * Remove an existing interface record from the network interface table.
114 *
115 */
sel_netif_destroy(struct sel_netif * netif)116 static void sel_netif_destroy(struct sel_netif *netif)
117 {
118 list_del_rcu(&netif->list);
119 sel_netif_total--;
120 kfree_rcu(netif, rcu_head);
121 }
122
123 /**
124 * sel_netif_sid_slow - Lookup the SID of a network interface using the policy
125 * @ns: the network namespace
126 * @ifindex: the network interface
127 * @sid: interface SID
128 *
129 * Description:
130 * This function determines the SID of a network interface by quering the
131 * security policy. The result is added to the network interface table to
132 * speedup future queries. Returns zero on success, negative values on
133 * failure.
134 *
135 */
sel_netif_sid_slow(struct net * ns,int ifindex,u32 * sid)136 static int sel_netif_sid_slow(struct net *ns, int ifindex, u32 *sid)
137 {
138 int ret;
139 struct sel_netif *netif;
140 struct sel_netif *new = NULL;
141 struct net_device *dev;
142
143 /* NOTE: we always use init's network namespace since we don't
144 * currently support containers */
145
146 dev = dev_get_by_index(ns, ifindex);
147 if (unlikely(dev == NULL)) {
148 printk(KERN_WARNING
149 "SELinux: failure in sel_netif_sid_slow(),"
150 " invalid network interface (%d)\n", ifindex);
151 return -ENOENT;
152 }
153
154 spin_lock_bh(&sel_netif_lock);
155 netif = sel_netif_find(ns, ifindex);
156 if (netif != NULL) {
157 *sid = netif->nsec.sid;
158 ret = 0;
159 goto out;
160 }
161 new = kzalloc(sizeof(*new), GFP_ATOMIC);
162 if (new == NULL) {
163 ret = -ENOMEM;
164 goto out;
165 }
166 ret = security_netif_sid(dev->name, &new->nsec.sid);
167 if (ret != 0)
168 goto out;
169 new->nsec.ns = ns;
170 new->nsec.ifindex = ifindex;
171 ret = sel_netif_insert(new);
172 if (ret != 0)
173 goto out;
174 *sid = new->nsec.sid;
175
176 out:
177 spin_unlock_bh(&sel_netif_lock);
178 dev_put(dev);
179 if (unlikely(ret)) {
180 printk(KERN_WARNING
181 "SELinux: failure in sel_netif_sid_slow(),"
182 " unable to determine network interface label (%d)\n",
183 ifindex);
184 kfree(new);
185 }
186 return ret;
187 }
188
189 /**
190 * sel_netif_sid - Lookup the SID of a network interface
191 * @ns: the network namespace
192 * @ifindex: the network interface
193 * @sid: interface SID
194 *
195 * Description:
196 * This function determines the SID of a network interface using the fastest
197 * method possible. First the interface table is queried, but if an entry
198 * can't be found then the policy is queried and the result is added to the
199 * table to speedup future queries. Returns zero on success, negative values
200 * on failure.
201 *
202 */
sel_netif_sid(struct net * ns,int ifindex,u32 * sid)203 int sel_netif_sid(struct net *ns, int ifindex, u32 *sid)
204 {
205 struct sel_netif *netif;
206
207 rcu_read_lock();
208 netif = sel_netif_find(ns, ifindex);
209 if (likely(netif != NULL)) {
210 *sid = netif->nsec.sid;
211 rcu_read_unlock();
212 return 0;
213 }
214 rcu_read_unlock();
215
216 return sel_netif_sid_slow(ns, ifindex, sid);
217 }
218
219 /**
220 * sel_netif_kill - Remove an entry from the network interface table
221 * @ns: the network namespace
222 * @ifindex: the network interface
223 *
224 * Description:
225 * This function removes the entry matching @ifindex from the network interface
226 * table if it exists.
227 *
228 */
sel_netif_kill(const struct net * ns,int ifindex)229 static void sel_netif_kill(const struct net *ns, int ifindex)
230 {
231 struct sel_netif *netif;
232
233 rcu_read_lock();
234 spin_lock_bh(&sel_netif_lock);
235 netif = sel_netif_find(ns, ifindex);
236 if (netif)
237 sel_netif_destroy(netif);
238 spin_unlock_bh(&sel_netif_lock);
239 rcu_read_unlock();
240 }
241
242 /**
243 * sel_netif_flush - Flush the entire network interface table
244 *
245 * Description:
246 * Remove all entries from the network interface table.
247 *
248 */
sel_netif_flush(void)249 void sel_netif_flush(void)
250 {
251 int idx;
252 struct sel_netif *netif;
253
254 spin_lock_bh(&sel_netif_lock);
255 for (idx = 0; idx < SEL_NETIF_HASH_SIZE; idx++)
256 list_for_each_entry(netif, &sel_netif_hash[idx], list)
257 sel_netif_destroy(netif);
258 spin_unlock_bh(&sel_netif_lock);
259 }
260
sel_netif_netdev_notifier_handler(struct notifier_block * this,unsigned long event,void * ptr)261 static int sel_netif_netdev_notifier_handler(struct notifier_block *this,
262 unsigned long event, void *ptr)
263 {
264 struct net_device *dev = netdev_notifier_info_to_dev(ptr);
265
266 if (event == NETDEV_DOWN)
267 sel_netif_kill(dev_net(dev), dev->ifindex);
268
269 return NOTIFY_DONE;
270 }
271
272 static struct notifier_block sel_netif_netdev_notifier = {
273 .notifier_call = sel_netif_netdev_notifier_handler,
274 };
275
sel_netif_init(void)276 static __init int sel_netif_init(void)
277 {
278 int i;
279
280 if (!selinux_enabled)
281 return 0;
282
283 for (i = 0; i < SEL_NETIF_HASH_SIZE; i++)
284 INIT_LIST_HEAD(&sel_netif_hash[i]);
285
286 register_netdevice_notifier(&sel_netif_netdev_notifier);
287
288 return 0;
289 }
290
291 __initcall(sel_netif_init);
292
293