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 "security.h"
26 #include "objsec.h"
27 #include "netif.h"
28
29 #define SEL_NETIF_HASH_SIZE 64
30 #define SEL_NETIF_HASH_MAX 1024
31
32 struct sel_netif {
33 struct list_head list;
34 struct netif_security_struct nsec;
35 struct rcu_head rcu_head;
36 };
37
38 static u32 sel_netif_total;
39 static LIST_HEAD(sel_netif_list);
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 int 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 int 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 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 */
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(&selinux_state, dev->name, sid);
158 if (ret != 0)
159 goto out;
160 new = kzalloc(sizeof(*new), GFP_ATOMIC);
161 if (new) {
162 new->nsec.ns = ns;
163 new->nsec.ifindex = ifindex;
164 new->nsec.sid = *sid;
165 if (sel_netif_insert(new))
166 kfree(new);
167 }
168
169 out:
170 spin_unlock_bh(&sel_netif_lock);
171 dev_put(dev);
172 if (unlikely(ret))
173 pr_warn("SELinux: failure in %s(), unable to determine network interface label (%d)\n",
174 __func__, ifindex);
175 return ret;
176 }
177
178 /**
179 * sel_netif_sid - Lookup the SID of a network interface
180 * @ns: the network namespace
181 * @ifindex: the network interface
182 * @sid: interface SID
183 *
184 * Description:
185 * This function determines the SID of a network interface using the fastest
186 * method possible. First the interface table is queried, but if an entry
187 * can't be found then the policy is queried and the result is added to the
188 * table to speedup future queries. Returns zero on success, negative values
189 * on failure.
190 *
191 */
sel_netif_sid(struct net * ns,int ifindex,u32 * sid)192 int sel_netif_sid(struct net *ns, int ifindex, u32 *sid)
193 {
194 struct sel_netif *netif;
195
196 rcu_read_lock();
197 netif = sel_netif_find(ns, ifindex);
198 if (likely(netif != NULL)) {
199 *sid = netif->nsec.sid;
200 rcu_read_unlock();
201 return 0;
202 }
203 rcu_read_unlock();
204
205 return sel_netif_sid_slow(ns, ifindex, sid);
206 }
207
208 /**
209 * sel_netif_kill - Remove an entry from the network interface table
210 * @ns: the network namespace
211 * @ifindex: the network interface
212 *
213 * Description:
214 * This function removes the entry matching @ifindex from the network interface
215 * table if it exists.
216 *
217 */
sel_netif_kill(const struct net * ns,int ifindex)218 static void sel_netif_kill(const struct net *ns, int ifindex)
219 {
220 struct sel_netif *netif;
221
222 rcu_read_lock();
223 spin_lock_bh(&sel_netif_lock);
224 netif = sel_netif_find(ns, ifindex);
225 if (netif)
226 sel_netif_destroy(netif);
227 spin_unlock_bh(&sel_netif_lock);
228 rcu_read_unlock();
229 }
230
231 /**
232 * sel_netif_flush - Flush the entire network interface table
233 *
234 * Description:
235 * Remove all entries from the network interface table.
236 *
237 */
sel_netif_flush(void)238 void sel_netif_flush(void)
239 {
240 int idx;
241 struct sel_netif *netif;
242
243 spin_lock_bh(&sel_netif_lock);
244 for (idx = 0; idx < SEL_NETIF_HASH_SIZE; idx++)
245 list_for_each_entry(netif, &sel_netif_hash[idx], list)
246 sel_netif_destroy(netif);
247 spin_unlock_bh(&sel_netif_lock);
248 }
249
sel_netif_netdev_notifier_handler(struct notifier_block * this,unsigned long event,void * ptr)250 static int sel_netif_netdev_notifier_handler(struct notifier_block *this,
251 unsigned long event, void *ptr)
252 {
253 struct net_device *dev = netdev_notifier_info_to_dev(ptr);
254
255 if (event == NETDEV_DOWN)
256 sel_netif_kill(dev_net(dev), dev->ifindex);
257
258 return NOTIFY_DONE;
259 }
260
261 static struct notifier_block sel_netif_netdev_notifier = {
262 .notifier_call = sel_netif_netdev_notifier_handler,
263 };
264
sel_netif_init(void)265 static __init int sel_netif_init(void)
266 {
267 int i;
268
269 if (!selinux_enabled)
270 return 0;
271
272 for (i = 0; i < SEL_NETIF_HASH_SIZE; i++)
273 INIT_LIST_HEAD(&sel_netif_hash[i]);
274
275 register_netdevice_notifier(&sel_netif_netdev_notifier);
276
277 return 0;
278 }
279
280 __initcall(sel_netif_init);
281
282