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TOMOYO Linux Cross Reference
Linux/security/selinux/netif.c

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  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  * @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)
 56 {
 57         return (ifindex & (SEL_NETIF_HASH_SIZE - 1));
 58 }
 59 
 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  *
 68  */
 69 static inline struct sel_netif *sel_netif_find(int ifindex)
 70 {
 71         int idx = sel_netif_hashfn(ifindex);
 72         struct sel_netif *netif;
 73 
 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))
 78                         return netif;
 79 
 80         return NULL;
 81 }
 82 
 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  */
 92 static int sel_netif_insert(struct sel_netif *netif)
 93 {
 94         int idx;
 95 
 96         if (sel_netif_total >= SEL_NETIF_HASH_MAX)
 97                 return -ENOSPC;
 98 
 99         idx = sel_netif_hashfn(netif->nsec.ifindex);
100         list_add_rcu(&netif->list, &sel_netif_hash[idx]);
101         sel_netif_total++;
102 
103         return 0;
104 }
105 
106 /**
107  * sel_netif_destroy - Remove an interface record from the table
108  * @netif: the existing interface record
109  *
110  * Description:
111  * Remove an existing interface record from the network interface table.
112  *
113  */
114 static void sel_netif_destroy(struct sel_netif *netif)
115 {
116         list_del_rcu(&netif->list);
117         sel_netif_total--;
118         kfree_rcu(netif, rcu_head);
119 }
120 
121 /**
122  * sel_netif_sid_slow - Lookup the SID of a network interface using the policy
123  * @ifindex: the network interface
124  * @sid: interface SID
125  *
126  * Description:
127  * This function determines the SID of a network interface by quering the
128  * security policy.  The result is added to the network interface table to
129  * speedup future queries.  Returns zero on success, negative values on
130  * failure.
131  *
132  */
133 static int sel_netif_sid_slow(int ifindex, u32 *sid)
134 {
135         int ret;
136         struct sel_netif *netif;
137         struct sel_netif *new = NULL;
138         struct net_device *dev;
139 
140         /* NOTE: we always use init's network namespace since we don't
141          * currently support containers */
142 
143         dev = dev_get_by_index(&init_net, ifindex);
144         if (unlikely(dev == NULL)) {
145                 printk(KERN_WARNING
146                        "SELinux: failure in sel_netif_sid_slow(),"
147                        " invalid network interface (%d)\n", ifindex);
148                 return -ENOENT;
149         }
150 
151         spin_lock_bh(&sel_netif_lock);
152         netif = sel_netif_find(ifindex);
153         if (netif != NULL) {
154                 *sid = netif->nsec.sid;
155                 ret = 0;
156                 goto out;
157         }
158         new = kzalloc(sizeof(*new), GFP_ATOMIC);
159         if (new == NULL) {
160                 ret = -ENOMEM;
161                 goto out;
162         }
163         ret = security_netif_sid(dev->name, &new->nsec.sid);
164         if (ret != 0)
165                 goto out;
166         new->nsec.ifindex = ifindex;
167         ret = sel_netif_insert(new);
168         if (ret != 0)
169                 goto out;
170         *sid = new->nsec.sid;
171 
172 out:
173         spin_unlock_bh(&sel_netif_lock);
174         dev_put(dev);
175         if (unlikely(ret)) {
176                 printk(KERN_WARNING
177                        "SELinux: failure in sel_netif_sid_slow(),"
178                        " unable to determine network interface label (%d)\n",
179                        ifindex);
180                 kfree(new);
181         }
182         return ret;
183 }
184 
185 /**
186  * sel_netif_sid - Lookup the SID of a network interface
187  * @ifindex: the network interface
188  * @sid: interface SID
189  *
190  * Description:
191  * This function determines the SID of a network interface using the fastest
192  * method possible.  First the interface table is queried, but if an entry
193  * can't be found then the policy is queried and the result is added to the
194  * table to speedup future queries.  Returns zero on success, negative values
195  * on failure.
196  *
197  */
198 int sel_netif_sid(int ifindex, u32 *sid)
199 {
200         struct sel_netif *netif;
201 
202         rcu_read_lock();
203         netif = sel_netif_find(ifindex);
204         if (likely(netif != NULL)) {
205                 *sid = netif->nsec.sid;
206                 rcu_read_unlock();
207                 return 0;
208         }
209         rcu_read_unlock();
210 
211         return sel_netif_sid_slow(ifindex, sid);
212 }
213 
214 /**
215  * sel_netif_kill - Remove an entry from the network interface table
216  * @ifindex: the network interface
217  *
218  * Description:
219  * This function removes the entry matching @ifindex from the network interface
220  * table if it exists.
221  *
222  */
223 static void sel_netif_kill(int ifindex)
224 {
225         struct sel_netif *netif;
226 
227         rcu_read_lock();
228         spin_lock_bh(&sel_netif_lock);
229         netif = sel_netif_find(ifindex);
230         if (netif)
231                 sel_netif_destroy(netif);
232         spin_unlock_bh(&sel_netif_lock);
233         rcu_read_unlock();
234 }
235 
236 /**
237  * sel_netif_flush - Flush the entire network interface table
238  *
239  * Description:
240  * Remove all entries from the network interface table.
241  *
242  */
243 static void sel_netif_flush(void)
244 {
245         int idx;
246         struct sel_netif *netif;
247 
248         spin_lock_bh(&sel_netif_lock);
249         for (idx = 0; idx < SEL_NETIF_HASH_SIZE; idx++)
250                 list_for_each_entry(netif, &sel_netif_hash[idx], list)
251                         sel_netif_destroy(netif);
252         spin_unlock_bh(&sel_netif_lock);
253 }
254 
255 static int sel_netif_avc_callback(u32 event)
256 {
257         if (event == AVC_CALLBACK_RESET) {
258                 sel_netif_flush();
259                 synchronize_net();
260         }
261         return 0;
262 }
263 
264 static int sel_netif_netdev_notifier_handler(struct notifier_block *this,
265                                              unsigned long event, void *ptr)
266 {
267         struct net_device *dev = netdev_notifier_info_to_dev(ptr);
268 
269         if (dev_net(dev) != &init_net)
270                 return NOTIFY_DONE;
271 
272         if (event == NETDEV_DOWN)
273                 sel_netif_kill(dev->ifindex);
274 
275         return NOTIFY_DONE;
276 }
277 
278 static struct notifier_block sel_netif_netdev_notifier = {
279         .notifier_call = sel_netif_netdev_notifier_handler,
280 };
281 
282 static __init int sel_netif_init(void)
283 {
284         int i, err;
285 
286         if (!selinux_enabled)
287                 return 0;
288 
289         for (i = 0; i < SEL_NETIF_HASH_SIZE; i++)
290                 INIT_LIST_HEAD(&sel_netif_hash[i]);
291 
292         register_netdevice_notifier(&sel_netif_netdev_notifier);
293 
294         err = avc_add_callback(sel_netif_avc_callback, AVC_CALLBACK_RESET);
295         if (err)
296                 panic("avc_add_callback() failed, error %d\n", err);
297 
298         return err;
299 }
300 
301 __initcall(sel_netif_init);
302 
303 

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