1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Network node table
4 *
5 * SELinux must keep a mapping of network nodes to labels/SIDs. This
6 * mapping is maintained as part of the normal policy but a fast cache is
7 * needed to reduce the lookup overhead since most of these queries happen on
8 * a per-packet basis.
9 *
10 * Author: Paul Moore <paul@paul-moore.com>
11 *
12 * This code is heavily based on the "netif" concept originally developed by
13 * James Morris <jmorris@redhat.com>
14 * (see security/selinux/netif.c for more information)
15 */
16
17 /*
18 * (c) Copyright Hewlett-Packard Development Company, L.P., 2007
19 */
20
21 #include <linux/types.h>
22 #include <linux/rcupdate.h>
23 #include <linux/list.h>
24 #include <linux/slab.h>
25 #include <linux/spinlock.h>
26 #include <linux/in.h>
27 #include <linux/in6.h>
28 #include <linux/ip.h>
29 #include <linux/ipv6.h>
30 #include <net/ip.h>
31 #include <net/ipv6.h>
32
33 #include "netnode.h"
34 #include "objsec.h"
35
36 #define SEL_NETNODE_HASH_SIZE 256
37 #define SEL_NETNODE_HASH_BKT_LIMIT 16
38
39 struct sel_netnode_bkt {
40 unsigned int size;
41 struct list_head list;
42 };
43
44 struct sel_netnode {
45 struct netnode_security_struct nsec;
46
47 struct list_head list;
48 struct rcu_head rcu;
49 };
50
51 /* NOTE: we are using a combined hash table for both IPv4 and IPv6, the reason
52 * for this is that I suspect most users will not make heavy use of both
53 * address families at the same time so one table will usually end up wasted,
54 * if this becomes a problem we can always add a hash table for each address
55 * family later */
56
57 static DEFINE_SPINLOCK(sel_netnode_lock);
58 static struct sel_netnode_bkt sel_netnode_hash[SEL_NETNODE_HASH_SIZE];
59
60 /**
61 * sel_netnode_hashfn_ipv4 - IPv4 hashing function for the node table
62 * @addr: IPv4 address
63 *
64 * Description:
65 * This is the IPv4 hashing function for the node interface table, it returns
66 * the bucket number for the given IP address.
67 *
68 */
69 static unsigned int sel_netnode_hashfn_ipv4(__be32 addr)
70 {
71 /* at some point we should determine if the mismatch in byte order
72 * affects the hash function dramatically */
73 return (addr & (SEL_NETNODE_HASH_SIZE - 1));
74 }
75
76 /**
77 * sel_netnode_hashfn_ipv6 - IPv6 hashing function for the node table
78 * @addr: IPv6 address
79 *
80 * Description:
81 * This is the IPv6 hashing function for the node interface table, it returns
82 * the bucket number for the given IP address.
83 *
84 */
85 static unsigned int sel_netnode_hashfn_ipv6(const struct in6_addr *addr)
86 {
87 /* just hash the least significant 32 bits to keep things fast (they
88 * are the most likely to be different anyway), we can revisit this
89 * later if needed */
90 return (addr->s6_addr32[3] & (SEL_NETNODE_HASH_SIZE - 1));
91 }
92
93 /**
94 * sel_netnode_find - Search for a node record
95 * @addr: IP address
96 * @family: address family
97 *
98 * Description:
99 * Search the network node table and return the record matching @addr. If an
100 * entry can not be found in the table return NULL.
101 *
102 */
103 static struct sel_netnode *sel_netnode_find(const void *addr, u16 family)
104 {
105 unsigned int idx;
106 struct sel_netnode *node;
107
108 switch (family) {
109 case PF_INET:
110 idx = sel_netnode_hashfn_ipv4(*(const __be32 *)addr);
111 break;
112 case PF_INET6:
113 idx = sel_netnode_hashfn_ipv6(addr);
114 break;
115 default:
116 BUG();
117 return NULL;
118 }
119
120 list_for_each_entry_rcu(node, &sel_netnode_hash[idx].list, list)
121 if (node->nsec.family == family)
122 switch (family) {
123 case PF_INET:
124 if (node->nsec.addr.ipv4 == *(const __be32 *)addr)
125 return node;
126 break;
127 case PF_INET6:
128 if (ipv6_addr_equal(&node->nsec.addr.ipv6,
129 addr))
130 return node;
131 break;
132 }
133
134 return NULL;
135 }
136
137 /**
138 * sel_netnode_insert - Insert a new node into the table
139 * @node: the new node record
140 *
141 * Description:
142 * Add a new node record to the network address hash table.
143 *
144 */
145 static void sel_netnode_insert(struct sel_netnode *node)
146 {
147 unsigned int idx;
148
149 switch (node->nsec.family) {
150 case PF_INET:
151 idx = sel_netnode_hashfn_ipv4(node->nsec.addr.ipv4);
152 break;
153 case PF_INET6:
154 idx = sel_netnode_hashfn_ipv6(&node->nsec.addr.ipv6);
155 break;
156 default:
157 BUG();
158 return;
159 }
160
161 /* we need to impose a limit on the growth of the hash table so check
162 * this bucket to make sure it is within the specified bounds */
163 list_add_rcu(&node->list, &sel_netnode_hash[idx].list);
164 if (sel_netnode_hash[idx].size == SEL_NETNODE_HASH_BKT_LIMIT) {
165 struct sel_netnode *tail;
166 tail = list_entry(
167 rcu_dereference_protected(
168 list_tail_rcu(&sel_netnode_hash[idx].list),
169 lockdep_is_held(&sel_netnode_lock)),
170 struct sel_netnode, list);
171 list_del_rcu(&tail->list);
172 kfree_rcu(tail, rcu);
173 } else
174 sel_netnode_hash[idx].size++;
175 }
176
177 /**
178 * sel_netnode_sid_slow - Lookup the SID of a network address using the policy
179 * @addr: the IP address
180 * @family: the address family
181 * @sid: node SID
182 *
183 * Description:
184 * This function determines the SID of a network address by querying the
185 * security policy. The result is added to the network address table to
186 * speedup future queries. Returns zero on success, negative values on
187 * failure.
188 *
189 */
190 static int sel_netnode_sid_slow(void *addr, u16 family, u32 *sid)
191 {
192 int ret;
193 struct sel_netnode *node;
194 struct sel_netnode *new;
195
196 spin_lock_bh(&sel_netnode_lock);
197 node = sel_netnode_find(addr, family);
198 if (node != NULL) {
199 *sid = node->nsec.sid;
200 spin_unlock_bh(&sel_netnode_lock);
201 return 0;
202 }
203
204 new = kzalloc(sizeof(*new), GFP_ATOMIC);
205 switch (family) {
206 case PF_INET:
207 ret = security_node_sid(PF_INET,
208 addr, sizeof(struct in_addr), sid);
209 if (new)
210 new->nsec.addr.ipv4 = *(__be32 *)addr;
211 break;
212 case PF_INET6:
213 ret = security_node_sid(PF_INET6,
214 addr, sizeof(struct in6_addr), sid);
215 if (new)
216 new->nsec.addr.ipv6 = *(struct in6_addr *)addr;
217 break;
218 default:
219 BUG();
220 ret = -EINVAL;
221 }
222 if (ret == 0 && new) {
223 new->nsec.family = family;
224 new->nsec.sid = *sid;
225 sel_netnode_insert(new);
226 } else
227 kfree(new);
228
229 spin_unlock_bh(&sel_netnode_lock);
230 if (unlikely(ret))
231 pr_warn("SELinux: failure in %s(), unable to determine network node label\n",
232 __func__);
233 return ret;
234 }
235
236 /**
237 * sel_netnode_sid - Lookup the SID of a network address
238 * @addr: the IP address
239 * @family: the address family
240 * @sid: node SID
241 *
242 * Description:
243 * This function determines the SID of a network address using the fastest
244 * method possible. First the address table is queried, but if an entry
245 * can't be found then the policy is queried and the result is added to the
246 * table to speedup future queries. Returns zero on success, negative values
247 * on failure.
248 *
249 */
250 int sel_netnode_sid(void *addr, u16 family, u32 *sid)
251 {
252 struct sel_netnode *node;
253
254 rcu_read_lock();
255 node = sel_netnode_find(addr, family);
256 if (node != NULL) {
257 *sid = node->nsec.sid;
258 rcu_read_unlock();
259 return 0;
260 }
261 rcu_read_unlock();
262
263 return sel_netnode_sid_slow(addr, family, sid);
264 }
265
266 /**
267 * sel_netnode_flush - Flush the entire network address table
268 *
269 * Description:
270 * Remove all entries from the network address table.
271 *
272 */
273 void sel_netnode_flush(void)
274 {
275 unsigned int idx;
276 struct sel_netnode *node, *node_tmp;
277
278 spin_lock_bh(&sel_netnode_lock);
279 for (idx = 0; idx < SEL_NETNODE_HASH_SIZE; idx++) {
280 list_for_each_entry_safe(node, node_tmp,
281 &sel_netnode_hash[idx].list, list) {
282 list_del_rcu(&node->list);
283 kfree_rcu(node, rcu);
284 }
285 sel_netnode_hash[idx].size = 0;
286 }
287 spin_unlock_bh(&sel_netnode_lock);
288 }
289
290 static __init int sel_netnode_init(void)
291 {
292 int iter;
293
294 if (!selinux_enabled_boot)
295 return 0;
296
297 for (iter = 0; iter < SEL_NETNODE_HASH_SIZE; iter++) {
298 INIT_LIST_HEAD(&sel_netnode_hash[iter].list);
299 sel_netnode_hash[iter].size = 0;
300 }
301
302 return 0;
303 }
304
305 __initcall(sel_netnode_init);
306
Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.