blob: 7100072bb1b0c88f56f4b9e50a48fa675338e297 [file] [log] [blame]
Paul Moore224dfbd2008-01-29 08:38:13 -05001/*
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.moore@hp.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/spinlock.h>
35#include <linux/in.h>
36#include <linux/in6.h>
37#include <linux/ip.h>
38#include <linux/ipv6.h>
39#include <net/ip.h>
40#include <net/ipv6.h>
Paul Moore224dfbd2008-01-29 08:38:13 -050041
Paul Moorea639e7ca2008-04-25 15:03:34 -040042#include "netnode.h"
Paul Moore224dfbd2008-01-29 08:38:13 -050043#include "objsec.h"
44
45#define SEL_NETNODE_HASH_SIZE 256
46#define SEL_NETNODE_HASH_BKT_LIMIT 16
47
Paul Moorea639e7ca2008-04-25 15:03:34 -040048struct sel_netnode_bkt {
49 unsigned int size;
50 struct list_head list;
51};
52
Paul Moore224dfbd2008-01-29 08:38:13 -050053struct sel_netnode {
54 struct netnode_security_struct nsec;
55
56 struct list_head list;
57 struct rcu_head rcu;
58};
59
60/* NOTE: we are using a combined hash table for both IPv4 and IPv6, the reason
61 * for this is that I suspect most users will not make heavy use of both
62 * address families at the same time so one table will usually end up wasted,
63 * if this becomes a problem we can always add a hash table for each address
64 * family later */
65
66static LIST_HEAD(sel_netnode_list);
67static DEFINE_SPINLOCK(sel_netnode_lock);
Paul Moorea639e7ca2008-04-25 15:03:34 -040068static struct sel_netnode_bkt sel_netnode_hash[SEL_NETNODE_HASH_SIZE];
Paul Moore224dfbd2008-01-29 08:38:13 -050069
70/**
71 * sel_netnode_free - Frees a node entry
72 * @p: the entry's RCU field
73 *
74 * Description:
75 * This function is designed to be used as a callback to the call_rcu()
76 * function so that memory allocated to a hash table node entry can be
77 * released safely.
78 *
79 */
80static void sel_netnode_free(struct rcu_head *p)
81{
82 struct sel_netnode *node = container_of(p, struct sel_netnode, rcu);
83 kfree(node);
84}
85
86/**
87 * sel_netnode_hashfn_ipv4 - IPv4 hashing function for the node table
88 * @addr: IPv4 address
89 *
90 * Description:
91 * This is the IPv4 hashing function for the node interface table, it returns
92 * the bucket number for the given IP address.
93 *
94 */
Paul Moorea639e7ca2008-04-25 15:03:34 -040095static unsigned int sel_netnode_hashfn_ipv4(__be32 addr)
Paul Moore224dfbd2008-01-29 08:38:13 -050096{
97 /* at some point we should determine if the mismatch in byte order
98 * affects the hash function dramatically */
99 return (addr & (SEL_NETNODE_HASH_SIZE - 1));
100}
101
102/**
103 * sel_netnode_hashfn_ipv6 - IPv6 hashing function for the node table
104 * @addr: IPv6 address
105 *
106 * Description:
107 * This is the IPv6 hashing function for the node interface table, it returns
108 * the bucket number for the given IP address.
109 *
110 */
Paul Moorea639e7ca2008-04-25 15:03:34 -0400111static unsigned int sel_netnode_hashfn_ipv6(const struct in6_addr *addr)
Paul Moore224dfbd2008-01-29 08:38:13 -0500112{
113 /* just hash the least significant 32 bits to keep things fast (they
114 * are the most likely to be different anyway), we can revisit this
115 * later if needed */
116 return (addr->s6_addr32[3] & (SEL_NETNODE_HASH_SIZE - 1));
117}
118
119/**
120 * sel_netnode_find - Search for a node record
121 * @addr: IP address
122 * @family: address family
123 *
124 * Description:
125 * Search the network node table and return the record matching @addr. If an
126 * entry can not be found in the table return NULL.
127 *
128 */
129static struct sel_netnode *sel_netnode_find(const void *addr, u16 family)
130{
Paul Moorea639e7ca2008-04-25 15:03:34 -0400131 unsigned int idx;
Paul Moore224dfbd2008-01-29 08:38:13 -0500132 struct sel_netnode *node;
133
134 switch (family) {
135 case PF_INET:
136 idx = sel_netnode_hashfn_ipv4(*(__be32 *)addr);
137 break;
138 case PF_INET6:
139 idx = sel_netnode_hashfn_ipv6(addr);
140 break;
141 default:
142 BUG();
143 }
144
Paul Moorea639e7ca2008-04-25 15:03:34 -0400145 list_for_each_entry_rcu(node, &sel_netnode_hash[idx].list, list)
Paul Moore224dfbd2008-01-29 08:38:13 -0500146 if (node->nsec.family == family)
147 switch (family) {
148 case PF_INET:
149 if (node->nsec.addr.ipv4 == *(__be32 *)addr)
150 return node;
151 break;
152 case PF_INET6:
153 if (ipv6_addr_equal(&node->nsec.addr.ipv6,
154 addr))
155 return node;
156 break;
157 }
158
159 return NULL;
160}
161
162/**
163 * sel_netnode_insert - Insert a new node into the table
164 * @node: the new node record
165 *
166 * Description:
Paul Moorea639e7ca2008-04-25 15:03:34 -0400167 * Add a new node record to the network address hash table.
Paul Moore224dfbd2008-01-29 08:38:13 -0500168 *
169 */
Paul Moorea639e7ca2008-04-25 15:03:34 -0400170static void sel_netnode_insert(struct sel_netnode *node)
Paul Moore224dfbd2008-01-29 08:38:13 -0500171{
Paul Moorea639e7ca2008-04-25 15:03:34 -0400172 unsigned int idx;
Paul Moore224dfbd2008-01-29 08:38:13 -0500173
174 switch (node->nsec.family) {
175 case PF_INET:
176 idx = sel_netnode_hashfn_ipv4(node->nsec.addr.ipv4);
177 break;
178 case PF_INET6:
179 idx = sel_netnode_hashfn_ipv6(&node->nsec.addr.ipv6);
180 break;
181 default:
182 BUG();
183 }
Paul Moorea639e7ca2008-04-25 15:03:34 -0400184
185 INIT_RCU_HEAD(&node->rcu);
Paul Moore224dfbd2008-01-29 08:38:13 -0500186
187 /* we need to impose a limit on the growth of the hash table so check
188 * this bucket to make sure it is within the specified bounds */
Paul Moorea639e7ca2008-04-25 15:03:34 -0400189 list_add_rcu(&node->list, &sel_netnode_hash[idx].list);
190 if (sel_netnode_hash[idx].size == SEL_NETNODE_HASH_BKT_LIMIT) {
191 struct sel_netnode *tail;
192 tail = list_entry(
193 rcu_dereference(sel_netnode_hash[idx].list.prev),
194 struct sel_netnode, list);
195 list_del_rcu(&tail->list);
196 call_rcu(&tail->rcu, sel_netnode_free);
197 } else
198 sel_netnode_hash[idx].size++;
Paul Moore224dfbd2008-01-29 08:38:13 -0500199}
200
201/**
202 * sel_netnode_sid_slow - Lookup the SID of a network address using the policy
203 * @addr: the IP address
204 * @family: the address family
205 * @sid: node SID
206 *
207 * Description:
208 * This function determines the SID of a network address by quering the
209 * security policy. The result is added to the network address table to
210 * speedup future queries. Returns zero on success, negative values on
211 * failure.
212 *
213 */
214static int sel_netnode_sid_slow(void *addr, u16 family, u32 *sid)
215{
Paul Moorea639e7ca2008-04-25 15:03:34 -0400216 int ret = -ENOMEM;
Paul Moore224dfbd2008-01-29 08:38:13 -0500217 struct sel_netnode *node;
218 struct sel_netnode *new = NULL;
219
220 spin_lock_bh(&sel_netnode_lock);
221 node = sel_netnode_find(addr, family);
222 if (node != NULL) {
223 *sid = node->nsec.sid;
Paul Moorea639e7ca2008-04-25 15:03:34 -0400224 spin_unlock_bh(&sel_netnode_lock);
225 return 0;
Paul Moore224dfbd2008-01-29 08:38:13 -0500226 }
227 new = kzalloc(sizeof(*new), GFP_ATOMIC);
Paul Moorea639e7ca2008-04-25 15:03:34 -0400228 if (new == NULL)
Paul Moore224dfbd2008-01-29 08:38:13 -0500229 goto out;
Paul Moore224dfbd2008-01-29 08:38:13 -0500230 switch (family) {
231 case PF_INET:
232 ret = security_node_sid(PF_INET,
Paul Moorea639e7ca2008-04-25 15:03:34 -0400233 addr, sizeof(struct in_addr), sid);
Paul Moore224dfbd2008-01-29 08:38:13 -0500234 new->nsec.addr.ipv4 = *(__be32 *)addr;
235 break;
236 case PF_INET6:
237 ret = security_node_sid(PF_INET6,
Paul Moorea639e7ca2008-04-25 15:03:34 -0400238 addr, sizeof(struct in6_addr), sid);
Paul Moore224dfbd2008-01-29 08:38:13 -0500239 ipv6_addr_copy(&new->nsec.addr.ipv6, addr);
240 break;
241 default:
242 BUG();
243 }
244 if (ret != 0)
245 goto out;
Paul Moorea639e7ca2008-04-25 15:03:34 -0400246
Paul Moore224dfbd2008-01-29 08:38:13 -0500247 new->nsec.family = family;
Paul Moorea639e7ca2008-04-25 15:03:34 -0400248 new->nsec.sid = *sid;
249 sel_netnode_insert(new);
Paul Moore224dfbd2008-01-29 08:38:13 -0500250
251out:
252 spin_unlock_bh(&sel_netnode_lock);
Paul Moore71f1cb02008-01-29 08:51:16 -0500253 if (unlikely(ret)) {
254 printk(KERN_WARNING
255 "SELinux: failure in sel_netnode_sid_slow(),"
256 " unable to determine network node label\n");
Paul Moore224dfbd2008-01-29 08:38:13 -0500257 kfree(new);
Paul Moore71f1cb02008-01-29 08:51:16 -0500258 }
Paul Moore224dfbd2008-01-29 08:38:13 -0500259 return ret;
260}
261
262/**
263 * sel_netnode_sid - Lookup the SID of a network address
264 * @addr: the IP address
265 * @family: the address family
266 * @sid: node SID
267 *
268 * Description:
269 * This function determines the SID of a network address using the fastest
270 * method possible. First the address table is queried, but if an entry
271 * can't be found then the policy is queried and the result is added to the
272 * table to speedup future queries. Returns zero on success, negative values
273 * on failure.
274 *
275 */
276int sel_netnode_sid(void *addr, u16 family, u32 *sid)
277{
278 struct sel_netnode *node;
279
280 rcu_read_lock();
281 node = sel_netnode_find(addr, family);
282 if (node != NULL) {
283 *sid = node->nsec.sid;
284 rcu_read_unlock();
285 return 0;
286 }
287 rcu_read_unlock();
288
289 return sel_netnode_sid_slow(addr, family, sid);
290}
291
292/**
293 * sel_netnode_flush - Flush the entire network address table
294 *
295 * Description:
296 * Remove all entries from the network address table.
297 *
298 */
299static void sel_netnode_flush(void)
300{
Paul Moorea639e7ca2008-04-25 15:03:34 -0400301 unsigned int idx;
302 struct sel_netnode *node, *node_tmp;
Paul Moore224dfbd2008-01-29 08:38:13 -0500303
304 spin_lock_bh(&sel_netnode_lock);
Paul Moorea639e7ca2008-04-25 15:03:34 -0400305 for (idx = 0; idx < SEL_NETNODE_HASH_SIZE; idx++) {
306 list_for_each_entry_safe(node, node_tmp,
307 &sel_netnode_hash[idx].list, list) {
308 list_del_rcu(&node->list);
309 call_rcu(&node->rcu, sel_netnode_free);
310 }
311 sel_netnode_hash[idx].size = 0;
312 }
Paul Moore224dfbd2008-01-29 08:38:13 -0500313 spin_unlock_bh(&sel_netnode_lock);
314}
315
316static int sel_netnode_avc_callback(u32 event, u32 ssid, u32 tsid,
317 u16 class, u32 perms, u32 *retained)
318{
319 if (event == AVC_CALLBACK_RESET) {
320 sel_netnode_flush();
321 synchronize_net();
322 }
323 return 0;
324}
325
326static __init int sel_netnode_init(void)
327{
328 int iter;
329 int ret;
330
331 if (!selinux_enabled)
332 return 0;
333
Paul Moorea639e7ca2008-04-25 15:03:34 -0400334 for (iter = 0; iter < SEL_NETNODE_HASH_SIZE; iter++) {
335 INIT_LIST_HEAD(&sel_netnode_hash[iter].list);
336 sel_netnode_hash[iter].size = 0;
337 }
Paul Moore224dfbd2008-01-29 08:38:13 -0500338
339 ret = avc_add_callback(sel_netnode_avc_callback, AVC_CALLBACK_RESET,
Eric Paris7b6b2392008-04-18 17:38:25 -0400340 SECSID_NULL, SECSID_NULL, SECCLASS_NULL, 0);
Paul Moore224dfbd2008-01-29 08:38:13 -0500341 if (ret != 0)
342 panic("avc_add_callback() failed, error %d\n", ret);
343
344 return ret;
345}
346
347__initcall(sel_netnode_init);