1 /*
2 * Network node table
3 *
4 * SELinux must keep a mapping of network nodes to labels/SIDs. This
5 * mapping is maintained as part of the normal policy but a fast cache is
6 * needed to reduce the lookup overhead since most of these queries happen on
7 * a per-packet basis.
8 *
9 * Author: Paul Moore <paul@paul-moore.com>
10 *
11 * This code is heavily based on the "netif" concept originally developed by
12 * James Morris <jmorris@redhat.com>
13 * (see security/selinux/netif.c for more information)
14 *
15 */
16
17 /*
18 * (c) Copyright Hewlett-Packard Development Company, L.P., 2007
19 *
20 * This program is free software: you can redistribute it and/or modify
21 * it under the terms of version 2 of the GNU General Public License as
22 * published by the Free Software Foundation.
23 *
24 * This program is distributed in the hope that it will be useful,
25 * but WITHOUT ANY WARRANTY; without even the implied warranty of
26 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
27 * GNU General Public License for more details.
28 *
29 */
30
31 #include <linux/types.h>
32 #include <linux/rcupdate.h>
33 #include <linux/list.h>
34 #include <linux/slab.h>
35 #include <linux/spinlock.h>
36 #include <linux/in.h>
37 #include <linux/in6.h>
38 #include <linux/ip.h>
39 #include <linux/ipv6.h>
40 #include <net/ip.h>
41 #include <net/ipv6.h>
42
43 #include "netnode.h"
44 #include "objsec.h"
45
46 #define SEL_NETNODE_HASH_SIZE 256
47 #define SEL_NETNODE_HASH_BKT_LIMIT 16
48
49 struct sel_netnode_bkt {
50 unsigned int size;
51 struct list_head list;
52 };
53
54 struct sel_netnode {
55 struct netnode_security_struct nsec;
56
57 struct list_head list;
58 struct rcu_head rcu;
59 };
60
61 /* NOTE: we are using a combined hash table for both IPv4 and IPv6, the reason
62 * for this is that I suspect most users will not make heavy use of both
63 * address families at the same time so one table will usually end up wasted,
64 * if this becomes a problem we can always add a hash table for each address
65 * family later */
66
67 static LIST_HEAD(sel_netnode_list);
68 static DEFINE_SPINLOCK(sel_netnode_lock);
69 static struct sel_netnode_bkt sel_netnode_hash[SEL_NETNODE_HASH_SIZE];
70
71 /**
72 * sel_netnode_hashfn_ipv4 - IPv4 hashing function for the node table
73 * @addr: IPv4 address
74 *
75 * Description:
76 * This is the IPv4 hashing function for the node interface table, it returns
77 * the bucket number for the given IP address.
78 *
79 */
sel_netnode_hashfn_ipv4(__be32 addr)80 static unsigned int sel_netnode_hashfn_ipv4(__be32 addr)
81 {
82 /* at some point we should determine if the mismatch in byte order
83 * affects the hash function dramatically */
84 return (addr & (SEL_NETNODE_HASH_SIZE - 1));
85 }
86
87 /**
88 * sel_netnode_hashfn_ipv6 - IPv6 hashing function for the node table
89 * @addr: IPv6 address
90 *
91 * Description:
92 * This is the IPv6 hashing function for the node interface table, it returns
93 * the bucket number for the given IP address.
94 *
95 */
sel_netnode_hashfn_ipv6(const struct in6_addr * addr)96 static unsigned int sel_netnode_hashfn_ipv6(const struct in6_addr *addr)
97 {
98 /* just hash the least significant 32 bits to keep things fast (they
99 * are the most likely to be different anyway), we can revisit this
100 * later if needed */
101 return (addr->s6_addr32[3] & (SEL_NETNODE_HASH_SIZE - 1));
102 }
103
104 /**
105 * sel_netnode_find - Search for a node record
106 * @addr: IP address
107 * @family: address family
108 *
109 * Description:
110 * Search the network node table and return the record matching @addr. If an
111 * entry can not be found in the table return NULL.
112 *
113 */
sel_netnode_find(const void * addr,u16 family)114 static struct sel_netnode *sel_netnode_find(const void *addr, u16 family)
115 {
116 unsigned int idx;
117 struct sel_netnode *node;
118
119 switch (family) {
120 case PF_INET:
121 idx = sel_netnode_hashfn_ipv4(*(__be32 *)addr);
122 break;
123 case PF_INET6:
124 idx = sel_netnode_hashfn_ipv6(addr);
125 break;
126 default:
127 BUG();
128 return NULL;
129 }
130
131 list_for_each_entry_rcu(node, &sel_netnode_hash[idx].list, list)
132 if (node->nsec.family == family)
133 switch (family) {
134 case PF_INET:
135 if (node->nsec.addr.ipv4 == *(__be32 *)addr)
136 return node;
137 break;
138 case PF_INET6:
139 if (ipv6_addr_equal(&node->nsec.addr.ipv6,
140 addr))
141 return node;
142 break;
143 }
144
145 return NULL;
146 }
147
148 /**
149 * sel_netnode_insert - Insert a new node into the table
150 * @node: the new node record
151 *
152 * Description:
153 * Add a new node record to the network address hash table.
154 *
155 */
sel_netnode_insert(struct sel_netnode * node)156 static void sel_netnode_insert(struct sel_netnode *node)
157 {
158 unsigned int idx;
159
160 switch (node->nsec.family) {
161 case PF_INET:
162 idx = sel_netnode_hashfn_ipv4(node->nsec.addr.ipv4);
163 break;
164 case PF_INET6:
165 idx = sel_netnode_hashfn_ipv6(&node->nsec.addr.ipv6);
166 break;
167 default:
168 BUG();
169 return;
170 }
171
172 /* we need to impose a limit on the growth of the hash table so check
173 * this bucket to make sure it is within the specified bounds */
174 list_add_rcu(&node->list, &sel_netnode_hash[idx].list);
175 if (sel_netnode_hash[idx].size == SEL_NETNODE_HASH_BKT_LIMIT) {
176 struct sel_netnode *tail;
177 tail = list_entry(
178 rcu_dereference_protected(sel_netnode_hash[idx].list.prev,
179 lockdep_is_held(&sel_netnode_lock)),
180 struct sel_netnode, list);
181 list_del_rcu(&tail->list);
182 kfree_rcu(tail, rcu);
183 } else
184 sel_netnode_hash[idx].size++;
185 }
186
187 /**
188 * sel_netnode_sid_slow - Lookup the SID of a network address using the policy
189 * @addr: the IP address
190 * @family: the address family
191 * @sid: node SID
192 *
193 * Description:
194 * This function determines the SID of a network address by quering the
195 * security policy. The result is added to the network address table to
196 * speedup future queries. Returns zero on success, negative values on
197 * failure.
198 *
199 */
sel_netnode_sid_slow(void * addr,u16 family,u32 * sid)200 static int sel_netnode_sid_slow(void *addr, u16 family, u32 *sid)
201 {
202 int ret = -ENOMEM;
203 struct sel_netnode *node;
204 struct sel_netnode *new = NULL;
205
206 spin_lock_bh(&sel_netnode_lock);
207 node = sel_netnode_find(addr, family);
208 if (node != NULL) {
209 *sid = node->nsec.sid;
210 spin_unlock_bh(&sel_netnode_lock);
211 return 0;
212 }
213 new = kzalloc(sizeof(*new), GFP_ATOMIC);
214 if (new == NULL)
215 goto out;
216 switch (family) {
217 case PF_INET:
218 ret = security_node_sid(PF_INET,
219 addr, sizeof(struct in_addr), sid);
220 new->nsec.addr.ipv4 = *(__be32 *)addr;
221 break;
222 case PF_INET6:
223 ret = security_node_sid(PF_INET6,
224 addr, sizeof(struct in6_addr), sid);
225 new->nsec.addr.ipv6 = *(struct in6_addr *)addr;
226 break;
227 default:
228 BUG();
229 ret = -EINVAL;
230 }
231 if (ret != 0)
232 goto out;
233
234 new->nsec.family = family;
235 new->nsec.sid = *sid;
236 sel_netnode_insert(new);
237
238 out:
239 spin_unlock_bh(&sel_netnode_lock);
240 if (unlikely(ret)) {
241 printk(KERN_WARNING
242 "SELinux: failure in sel_netnode_sid_slow(),"
243 " unable to determine network node label\n");
244 kfree(new);
245 }
246 return ret;
247 }
248
249 /**
250 * sel_netnode_sid - Lookup the SID of a network address
251 * @addr: the IP address
252 * @family: the address family
253 * @sid: node SID
254 *
255 * Description:
256 * This function determines the SID of a network address using the fastest
257 * method possible. First the address table is queried, but if an entry
258 * can't be found then the policy is queried and the result is added to the
259 * table to speedup future queries. Returns zero on success, negative values
260 * on failure.
261 *
262 */
sel_netnode_sid(void * addr,u16 family,u32 * sid)263 int sel_netnode_sid(void *addr, u16 family, u32 *sid)
264 {
265 struct sel_netnode *node;
266
267 rcu_read_lock();
268 node = sel_netnode_find(addr, family);
269 if (node != NULL) {
270 *sid = node->nsec.sid;
271 rcu_read_unlock();
272 return 0;
273 }
274 rcu_read_unlock();
275
276 return sel_netnode_sid_slow(addr, family, sid);
277 }
278
279 /**
280 * sel_netnode_flush - Flush the entire network address table
281 *
282 * Description:
283 * Remove all entries from the network address table.
284 *
285 */
sel_netnode_flush(void)286 void sel_netnode_flush(void)
287 {
288 unsigned int idx;
289 struct sel_netnode *node, *node_tmp;
290
291 spin_lock_bh(&sel_netnode_lock);
292 for (idx = 0; idx < SEL_NETNODE_HASH_SIZE; idx++) {
293 list_for_each_entry_safe(node, node_tmp,
294 &sel_netnode_hash[idx].list, list) {
295 list_del_rcu(&node->list);
296 kfree_rcu(node, rcu);
297 }
298 sel_netnode_hash[idx].size = 0;
299 }
300 spin_unlock_bh(&sel_netnode_lock);
301 }
302
sel_netnode_init(void)303 static __init int sel_netnode_init(void)
304 {
305 int iter;
306
307 if (!selinux_enabled)
308 return 0;
309
310 for (iter = 0; iter < SEL_NETNODE_HASH_SIZE; iter++) {
311 INIT_LIST_HEAD(&sel_netnode_hash[iter].list);
312 sel_netnode_hash[iter].size = 0;
313 }
314
315 return 0;
316 }
317
318 __initcall(sel_netnode_init);
319