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