1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Network interface table.
4 *
5 * Network interfaces (devices) do not have a security field, so we
6 * maintain a table associating each interface with a SID.
7 *
8 * Author: James Morris <jmorris@redhat.com>
9 *
10 * Copyright (C) 2003 Red Hat, Inc., James Morris <jmorris@redhat.com>
11 * Copyright (C) 2007 Hewlett-Packard Development Company, L.P.
12 * Paul Moore <paul@paul-moore.com>
13 */
14 #include <linux/init.h>
15 #include <linux/types.h>
16 #include <linux/slab.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 #include <net/net_namespace.h>
24
25 #include "initcalls.h"
26 #include "security.h"
27 #include "objsec.h"
28 #include "netif.h"
29
30 #define SEL_NETIF_HASH_SIZE 64
31 #define SEL_NETIF_HASH_MAX 1024
32
33 struct sel_netif {
34 struct list_head list;
35 struct netif_security_struct nsec;
36 struct rcu_head rcu_head;
37 };
38
39 static u32 sel_netif_total;
40 static DEFINE_SPINLOCK(sel_netif_lock);
41 static struct list_head sel_netif_hash[SEL_NETIF_HASH_SIZE];
42
43 /**
44 * sel_netif_hashfn - Hashing function for the interface table
45 * @ns: the network namespace
46 * @ifindex: the network interface
47 *
48 * Description:
49 * This is the hashing function for the network interface table, it returns the
50 * bucket number for the given interface.
51 *
52 */
sel_netif_hashfn(const struct net * ns,int ifindex)53 static inline u32 sel_netif_hashfn(const struct net *ns, int ifindex)
54 {
55 return (((uintptr_t)ns + ifindex) & (SEL_NETIF_HASH_SIZE - 1));
56 }
57
58 /**
59 * sel_netif_find - Search for an interface record
60 * @ns: the network namespace
61 * @ifindex: the network interface
62 *
63 * Description:
64 * Search the network interface table and return the record matching @ifindex.
65 * If an entry can not be found in the table return NULL.
66 *
67 */
sel_netif_find(const struct net * ns,int ifindex)68 static inline struct sel_netif *sel_netif_find(const struct net *ns,
69 int ifindex)
70 {
71 u32 idx = sel_netif_hashfn(ns, ifindex);
72 struct sel_netif *netif;
73
74 list_for_each_entry_rcu(netif, &sel_netif_hash[idx], list)
75 if (net_eq(netif->nsec.ns, ns) &&
76 netif->nsec.ifindex == ifindex)
77 return netif;
78
79 return NULL;
80 }
81
82 /**
83 * sel_netif_insert - Insert a new interface into the table
84 * @netif: the new interface record
85 *
86 * Description:
87 * Add a new interface record to the network interface hash table. Returns
88 * zero on success, negative values on failure.
89 *
90 */
sel_netif_insert(struct sel_netif * netif)91 static int sel_netif_insert(struct sel_netif *netif)
92 {
93 u32 idx;
94
95 if (sel_netif_total >= SEL_NETIF_HASH_MAX)
96 return -ENOSPC;
97
98 idx = sel_netif_hashfn(netif->nsec.ns, netif->nsec.ifindex);
99 list_add_rcu(&netif->list, &sel_netif_hash[idx]);
100 sel_netif_total++;
101
102 return 0;
103 }
104
105 /**
106 * sel_netif_destroy - Remove an interface record from the table
107 * @netif: the existing interface record
108 *
109 * Description:
110 * Remove an existing interface record from the network interface table.
111 *
112 */
sel_netif_destroy(struct sel_netif * netif)113 static void sel_netif_destroy(struct sel_netif *netif)
114 {
115 list_del_rcu(&netif->list);
116 sel_netif_total--;
117 kfree_rcu(netif, rcu_head);
118 }
119
120 /**
121 * sel_netif_sid_slow - Lookup the SID of a network interface using the policy
122 * @ns: the network namespace
123 * @ifindex: the network interface
124 * @sid: interface SID
125 *
126 * Description:
127 * This function determines the SID of a network interface by querying 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 */
sel_netif_sid_slow(struct net * ns,int ifindex,u32 * sid)133 static int sel_netif_sid_slow(struct net *ns, int ifindex, u32 *sid)
134 {
135 int ret = 0;
136 struct sel_netif *netif;
137 struct sel_netif *new;
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(ns, ifindex);
144 if (unlikely(dev == NULL)) {
145 pr_warn("SELinux: failure in %s(), invalid network interface (%d)\n",
146 __func__, ifindex);
147 return -ENOENT;
148 }
149
150 spin_lock_bh(&sel_netif_lock);
151 netif = sel_netif_find(ns, ifindex);
152 if (netif != NULL) {
153 *sid = netif->nsec.sid;
154 goto out;
155 }
156
157 ret = security_netif_sid(dev->name, sid);
158 if (ret != 0)
159 goto out;
160
161 /* If this memory allocation fails still return 0. The SID
162 * is valid, it just won't be added to the cache.
163 */
164 new = kmalloc(sizeof(*new), GFP_ATOMIC);
165 if (new) {
166 new->nsec.ns = ns;
167 new->nsec.ifindex = ifindex;
168 new->nsec.sid = *sid;
169 if (sel_netif_insert(new))
170 kfree(new);
171 }
172
173 out:
174 spin_unlock_bh(&sel_netif_lock);
175 dev_put(dev);
176 if (unlikely(ret))
177 pr_warn("SELinux: failure in %s(), unable to determine network interface label (%d)\n",
178 __func__, ifindex);
179 return ret;
180 }
181
182 /**
183 * sel_netif_sid - Lookup the SID of a network interface
184 * @ns: the network namespace
185 * @ifindex: the network interface
186 * @sid: interface SID
187 *
188 * Description:
189 * This function determines the SID of a network interface using the fastest
190 * method possible. First the interface table is queried, but if an entry
191 * can't be found then the policy is queried and the result is added to the
192 * table to speedup future queries. Returns zero on success, negative values
193 * on failure.
194 *
195 */
sel_netif_sid(struct net * ns,int ifindex,u32 * sid)196 int sel_netif_sid(struct net *ns, int ifindex, u32 *sid)
197 {
198 struct sel_netif *netif;
199
200 rcu_read_lock();
201 netif = sel_netif_find(ns, ifindex);
202 if (likely(netif != NULL)) {
203 *sid = netif->nsec.sid;
204 rcu_read_unlock();
205 return 0;
206 }
207 rcu_read_unlock();
208
209 return sel_netif_sid_slow(ns, ifindex, sid);
210 }
211
212 /**
213 * sel_netif_kill - Remove an entry from the network interface table
214 * @ns: the network namespace
215 * @ifindex: the network interface
216 *
217 * Description:
218 * This function removes the entry matching @ifindex from the network interface
219 * table if it exists.
220 *
221 */
sel_netif_kill(const struct net * ns,int ifindex)222 static void sel_netif_kill(const struct net *ns, int ifindex)
223 {
224 struct sel_netif *netif;
225
226 rcu_read_lock();
227 spin_lock_bh(&sel_netif_lock);
228 netif = sel_netif_find(ns, ifindex);
229 if (netif)
230 sel_netif_destroy(netif);
231 spin_unlock_bh(&sel_netif_lock);
232 rcu_read_unlock();
233 }
234
235 /**
236 * sel_netif_flush - Flush the entire network interface table
237 *
238 * Description:
239 * Remove all entries from the network interface table.
240 *
241 */
sel_netif_flush(void)242 void sel_netif_flush(void)
243 {
244 int idx;
245 struct sel_netif *netif;
246
247 spin_lock_bh(&sel_netif_lock);
248 for (idx = 0; idx < SEL_NETIF_HASH_SIZE; idx++)
249 list_for_each_entry(netif, &sel_netif_hash[idx], list)
250 sel_netif_destroy(netif);
251 spin_unlock_bh(&sel_netif_lock);
252 }
253
sel_netif_netdev_notifier_handler(struct notifier_block * this,unsigned long event,void * ptr)254 static int sel_netif_netdev_notifier_handler(struct notifier_block *this,
255 unsigned long event, void *ptr)
256 {
257 struct net_device *dev = netdev_notifier_info_to_dev(ptr);
258
259 if (event == NETDEV_DOWN)
260 sel_netif_kill(dev_net(dev), dev->ifindex);
261
262 return NOTIFY_DONE;
263 }
264
265 static struct notifier_block sel_netif_netdev_notifier = {
266 .notifier_call = sel_netif_netdev_notifier_handler,
267 };
268
sel_netif_init(void)269 int __init sel_netif_init(void)
270 {
271 int i;
272
273 if (!selinux_enabled_boot)
274 return 0;
275
276 for (i = 0; i < SEL_NETIF_HASH_SIZE; i++)
277 INIT_LIST_HEAD(&sel_netif_hash[i]);
278
279 register_netdevice_notifier(&sel_netif_netdev_notifier);
280
281 return 0;
282 }
283
284