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1da177e4 LT |
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> | |
e8bfdb9d PM |
10 | * Copyright (C) 2007 Hewlett-Packard Development Company, L.P. |
11 | * Paul Moore <paul.moore@hp.com> | |
1da177e4 LT |
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/stddef.h> | |
20 | #include <linux/kernel.h> | |
21 | #include <linux/list.h> | |
22 | #include <linux/notifier.h> | |
23 | #include <linux/netdevice.h> | |
24 | #include <linux/rcupdate.h> | |
e9dc8653 | 25 | #include <net/net_namespace.h> |
1da177e4 LT |
26 | |
27 | #include "security.h" | |
28 | #include "objsec.h" | |
29 | #include "netif.h" | |
30 | ||
31 | #define SEL_NETIF_HASH_SIZE 64 | |
32 | #define SEL_NETIF_HASH_MAX 1024 | |
33 | ||
1da177e4 LT |
34 | struct sel_netif |
35 | { | |
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 | ||
e8bfdb9d PM |
46 | /** |
47 | * sel_netif_hashfn - Hashing function for the interface table | |
48 | * @ifindex: the network interface | |
49 | * | |
50 | * Description: | |
51 | * This is the hashing function for the network interface table, it returns the | |
52 | * bucket number for the given interface. | |
53 | * | |
54 | */ | |
55 | static inline u32 sel_netif_hashfn(int ifindex) | |
1da177e4 | 56 | { |
e8bfdb9d | 57 | return (ifindex & (SEL_NETIF_HASH_SIZE - 1)); |
1da177e4 LT |
58 | } |
59 | ||
e8bfdb9d PM |
60 | /** |
61 | * sel_netif_find - Search for an interface record | |
62 | * @ifindex: the network interface | |
63 | * | |
64 | * Description: | |
65 | * Search the network interface table and return the record matching @ifindex. | |
66 | * If an entry can not be found in the table return NULL. | |
67 | * | |
1da177e4 | 68 | */ |
e8bfdb9d | 69 | static inline struct sel_netif *sel_netif_find(int ifindex) |
1da177e4 | 70 | { |
e8bfdb9d PM |
71 | int idx = sel_netif_hashfn(ifindex); |
72 | struct sel_netif *netif; | |
1da177e4 | 73 | |
e8bfdb9d PM |
74 | list_for_each_entry_rcu(netif, &sel_netif_hash[idx], list) |
75 | /* all of the devices should normally fit in the hash, so we | |
76 | * optimize for that case */ | |
77 | if (likely(netif->nsec.ifindex == ifindex)) | |
1da177e4 | 78 | return netif; |
e8bfdb9d | 79 | |
1da177e4 LT |
80 | return NULL; |
81 | } | |
82 | ||
e8bfdb9d PM |
83 | /** |
84 | * sel_netif_insert - Insert a new interface into the table | |
85 | * @netif: the new interface record | |
86 | * | |
87 | * Description: | |
88 | * Add a new interface record to the network interface hash table. Returns | |
89 | * zero on success, negative values on failure. | |
90 | * | |
91 | */ | |
1da177e4 LT |
92 | static int sel_netif_insert(struct sel_netif *netif) |
93 | { | |
e8bfdb9d | 94 | int idx; |
1da177e4 | 95 | |
e8bfdb9d PM |
96 | if (sel_netif_total >= SEL_NETIF_HASH_MAX) |
97 | return -ENOSPC; | |
1da177e4 | 98 | |
e8bfdb9d | 99 | idx = sel_netif_hashfn(netif->nsec.ifindex); |
1da177e4 LT |
100 | list_add_rcu(&netif->list, &sel_netif_hash[idx]); |
101 | sel_netif_total++; | |
e8bfdb9d PM |
102 | |
103 | return 0; | |
1da177e4 LT |
104 | } |
105 | ||
e8bfdb9d PM |
106 | /** |
107 | * sel_netif_free - Frees an interface entry | |
108 | * @p: the entry's RCU field | |
109 | * | |
110 | * Description: | |
111 | * This function is designed to be used as a callback to the call_rcu() | |
112 | * function so that memory allocated to a hash table interface entry can be | |
113 | * released safely. | |
114 | * | |
115 | */ | |
1da177e4 LT |
116 | static void sel_netif_free(struct rcu_head *p) |
117 | { | |
118 | struct sel_netif *netif = container_of(p, struct sel_netif, rcu_head); | |
1da177e4 LT |
119 | kfree(netif); |
120 | } | |
121 | ||
e8bfdb9d PM |
122 | /** |
123 | * sel_netif_destroy - Remove an interface record from the table | |
124 | * @netif: the existing interface record | |
125 | * | |
126 | * Description: | |
127 | * Remove an existing interface record from the network interface table. | |
128 | * | |
129 | */ | |
1da177e4 LT |
130 | static void sel_netif_destroy(struct sel_netif *netif) |
131 | { | |
1da177e4 LT |
132 | list_del_rcu(&netif->list); |
133 | sel_netif_total--; | |
134 | call_rcu(&netif->rcu_head, sel_netif_free); | |
135 | } | |
136 | ||
e8bfdb9d PM |
137 | /** |
138 | * sel_netif_sid_slow - Lookup the SID of a network interface using the policy | |
139 | * @ifindex: the network interface | |
140 | * @sid: interface SID | |
141 | * | |
142 | * Description: | |
143 | * This function determines the SID of a network interface by quering the | |
144 | * security policy. The result is added to the network interface table to | |
145 | * speedup future queries. Returns zero on success, negative values on | |
146 | * failure. | |
147 | * | |
148 | */ | |
149 | static int sel_netif_sid_slow(int ifindex, u32 *sid) | |
1da177e4 LT |
150 | { |
151 | int ret; | |
e8bfdb9d PM |
152 | struct sel_netif *netif; |
153 | struct sel_netif *new = NULL; | |
154 | struct net_device *dev; | |
1da177e4 | 155 | |
e8bfdb9d PM |
156 | /* NOTE: we always use init's network namespace since we don't |
157 | * currently support containers */ | |
1da177e4 | 158 | |
e8bfdb9d PM |
159 | dev = dev_get_by_index(&init_net, ifindex); |
160 | if (dev == NULL) | |
161 | return -ENOENT; | |
1da177e4 | 162 | |
1da177e4 | 163 | spin_lock_bh(&sel_netif_lock); |
e8bfdb9d PM |
164 | netif = sel_netif_find(ifindex); |
165 | if (netif != NULL) { | |
166 | *sid = netif->nsec.sid; | |
167 | ret = 0; | |
1da177e4 LT |
168 | goto out; |
169 | } | |
e8bfdb9d PM |
170 | new = kzalloc(sizeof(*new), GFP_ATOMIC); |
171 | if (new == NULL) { | |
172 | ret = -ENOMEM; | |
1da177e4 LT |
173 | goto out; |
174 | } | |
e8bfdb9d PM |
175 | ret = security_netif_sid(dev->name, &new->nsec.sid); |
176 | if (ret != 0) | |
177 | goto out; | |
178 | new->nsec.ifindex = ifindex; | |
179 | ret = sel_netif_insert(new); | |
180 | if (ret != 0) | |
181 | goto out; | |
182 | *sid = new->nsec.sid; | |
1da177e4 | 183 | |
1da177e4 | 184 | out: |
e8bfdb9d PM |
185 | spin_unlock_bh(&sel_netif_lock); |
186 | dev_put(dev); | |
187 | if (ret != 0) | |
188 | kfree(new); | |
1da177e4 LT |
189 | return ret; |
190 | } | |
191 | ||
e8bfdb9d PM |
192 | /** |
193 | * sel_netif_sid - Lookup the SID of a network interface | |
194 | * @ifindex: the network interface | |
195 | * @sid: interface SID | |
196 | * | |
197 | * Description: | |
198 | * This function determines the SID of a network interface using the fastest | |
199 | * method possible. First the interface table is queried, but if an entry | |
200 | * can't be found then the policy is queried and the result is added to the | |
201 | * table to speedup future queries. Returns zero on success, negative values | |
202 | * on failure. | |
203 | * | |
204 | */ | |
205 | int sel_netif_sid(int ifindex, u32 *sid) | |
1da177e4 | 206 | { |
1da177e4 LT |
207 | struct sel_netif *netif; |
208 | ||
209 | rcu_read_lock(); | |
e8bfdb9d PM |
210 | netif = sel_netif_find(ifindex); |
211 | if (likely(netif != NULL)) { | |
212 | *sid = netif->nsec.sid; | |
1da177e4 | 213 | rcu_read_unlock(); |
e8bfdb9d | 214 | return 0; |
1da177e4 | 215 | } |
1da177e4 | 216 | rcu_read_unlock(); |
e8bfdb9d PM |
217 | |
218 | return sel_netif_sid_slow(ifindex, sid); | |
1da177e4 LT |
219 | } |
220 | ||
e8bfdb9d PM |
221 | /** |
222 | * sel_netif_kill - Remove an entry from the network interface table | |
223 | * @ifindex: the network interface | |
224 | * | |
225 | * Description: | |
226 | * This function removes the entry matching @ifindex from the network interface | |
227 | * table if it exists. | |
228 | * | |
229 | */ | |
230 | static void sel_netif_kill(int ifindex) | |
1da177e4 LT |
231 | { |
232 | struct sel_netif *netif; | |
233 | ||
234 | spin_lock_bh(&sel_netif_lock); | |
e8bfdb9d | 235 | netif = sel_netif_find(ifindex); |
1da177e4 LT |
236 | if (netif) |
237 | sel_netif_destroy(netif); | |
238 | spin_unlock_bh(&sel_netif_lock); | |
239 | } | |
240 | ||
e8bfdb9d PM |
241 | /** |
242 | * sel_netif_flush - Flush the entire network interface table | |
243 | * | |
244 | * Description: | |
245 | * Remove all entries from the network interface table. | |
246 | * | |
247 | */ | |
1da177e4 LT |
248 | static void sel_netif_flush(void) |
249 | { | |
250 | int idx; | |
e8bfdb9d | 251 | struct sel_netif *netif; |
1da177e4 LT |
252 | |
253 | spin_lock_bh(&sel_netif_lock); | |
e8bfdb9d | 254 | for (idx = 0; idx < SEL_NETIF_HASH_SIZE; idx++) |
1da177e4 LT |
255 | list_for_each_entry(netif, &sel_netif_hash[idx], list) |
256 | sel_netif_destroy(netif); | |
1da177e4 LT |
257 | spin_unlock_bh(&sel_netif_lock); |
258 | } | |
259 | ||
260 | static int sel_netif_avc_callback(u32 event, u32 ssid, u32 tsid, | |
261 | u16 class, u32 perms, u32 *retained) | |
262 | { | |
263 | if (event == AVC_CALLBACK_RESET) { | |
264 | sel_netif_flush(); | |
265 | synchronize_net(); | |
266 | } | |
267 | return 0; | |
268 | } | |
269 | ||
270 | static int sel_netif_netdev_notifier_handler(struct notifier_block *this, | |
271 | unsigned long event, void *ptr) | |
272 | { | |
273 | struct net_device *dev = ptr; | |
274 | ||
e9dc8653 EB |
275 | if (dev->nd_net != &init_net) |
276 | return NOTIFY_DONE; | |
277 | ||
1da177e4 | 278 | if (event == NETDEV_DOWN) |
e8bfdb9d | 279 | sel_netif_kill(dev->ifindex); |
1da177e4 LT |
280 | |
281 | return NOTIFY_DONE; | |
282 | } | |
283 | ||
284 | static struct notifier_block sel_netif_netdev_notifier = { | |
285 | .notifier_call = sel_netif_netdev_notifier_handler, | |
286 | }; | |
287 | ||
288 | static __init int sel_netif_init(void) | |
289 | { | |
e8bfdb9d | 290 | int i, err; |
1da177e4 LT |
291 | |
292 | if (!selinux_enabled) | |
e8bfdb9d | 293 | return 0; |
1da177e4 LT |
294 | |
295 | for (i = 0; i < SEL_NETIF_HASH_SIZE; i++) | |
296 | INIT_LIST_HEAD(&sel_netif_hash[i]); | |
297 | ||
298 | register_netdevice_notifier(&sel_netif_netdev_notifier); | |
299 | ||
300 | err = avc_add_callback(sel_netif_avc_callback, AVC_CALLBACK_RESET, | |
301 | SECSID_NULL, SECSID_NULL, SECCLASS_NULL, 0); | |
302 | if (err) | |
303 | panic("avc_add_callback() failed, error %d\n", err); | |
304 | ||
1da177e4 LT |
305 | return err; |
306 | } | |
307 | ||
308 | __initcall(sel_netif_init); | |
309 |