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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>
Tejun Heo5a0e3ad2010-03-24 17:04:11 +090034#include <linux/slab.h>
Paul Moore224dfbd2008-01-29 08:38:13 -050035#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>
Paul Moore224dfbd2008-01-29 08:38:13 -050042
Paul Moorea639e7ca2008-04-25 15:03:34 -040043#include "netnode.h"
Paul Moore224dfbd2008-01-29 08:38:13 -050044#include "objsec.h"
45
46#define SEL_NETNODE_HASH_SIZE 256
47#define SEL_NETNODE_HASH_BKT_LIMIT 16
48
Paul Moorea639e7ca2008-04-25 15:03:34 -040049struct sel_netnode_bkt {
50 unsigned int size;
51 struct list_head list;
52};
53
Paul Moore224dfbd2008-01-29 08:38:13 -050054struct 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
67static LIST_HEAD(sel_netnode_list);
68static DEFINE_SPINLOCK(sel_netnode_lock);
Paul Moorea639e7ca2008-04-25 15:03:34 -040069static struct sel_netnode_bkt sel_netnode_hash[SEL_NETNODE_HASH_SIZE];
Paul Moore224dfbd2008-01-29 08:38:13 -050070
71/**
72 * sel_netnode_free - Frees a node entry
73 * @p: the entry's RCU field
74 *
75 * Description:
76 * This function is designed to be used as a callback to the call_rcu()
77 * function so that memory allocated to a hash table node entry can be
78 * released safely.
79 *
80 */
81static void sel_netnode_free(struct rcu_head *p)
82{
83 struct sel_netnode *node = container_of(p, struct sel_netnode, rcu);
84 kfree(node);
85}
86
87/**
88 * sel_netnode_hashfn_ipv4 - IPv4 hashing function for the node table
89 * @addr: IPv4 address
90 *
91 * Description:
92 * This is the IPv4 hashing function for the node interface table, it returns
93 * the bucket number for the given IP address.
94 *
95 */
Paul Moorea639e7ca2008-04-25 15:03:34 -040096static unsigned int sel_netnode_hashfn_ipv4(__be32 addr)
Paul Moore224dfbd2008-01-29 08:38:13 -050097{
98 /* at some point we should determine if the mismatch in byte order
99 * affects the hash function dramatically */
100 return (addr & (SEL_NETNODE_HASH_SIZE - 1));
101}
102
103/**
104 * sel_netnode_hashfn_ipv6 - IPv6 hashing function for the node table
105 * @addr: IPv6 address
106 *
107 * Description:
108 * This is the IPv6 hashing function for the node interface table, it returns
109 * the bucket number for the given IP address.
110 *
111 */
Paul Moorea639e7ca2008-04-25 15:03:34 -0400112static unsigned int sel_netnode_hashfn_ipv6(const struct in6_addr *addr)
Paul Moore224dfbd2008-01-29 08:38:13 -0500113{
114 /* just hash the least significant 32 bits to keep things fast (they
115 * are the most likely to be different anyway), we can revisit this
116 * later if needed */
117 return (addr->s6_addr32[3] & (SEL_NETNODE_HASH_SIZE - 1));
118}
119
120/**
121 * sel_netnode_find - Search for a node record
122 * @addr: IP address
123 * @family: address family
124 *
125 * Description:
126 * Search the network node table and return the record matching @addr. If an
127 * entry can not be found in the table return NULL.
128 *
129 */
130static struct sel_netnode *sel_netnode_find(const void *addr, u16 family)
131{
Paul Moorea639e7ca2008-04-25 15:03:34 -0400132 unsigned int idx;
Paul Moore224dfbd2008-01-29 08:38:13 -0500133 struct sel_netnode *node;
134
135 switch (family) {
136 case PF_INET:
137 idx = sel_netnode_hashfn_ipv4(*(__be32 *)addr);
138 break;
139 case PF_INET6:
140 idx = sel_netnode_hashfn_ipv6(addr);
141 break;
142 default:
143 BUG();
144 }
145
Paul Moorea639e7ca2008-04-25 15:03:34 -0400146 list_for_each_entry_rcu(node, &sel_netnode_hash[idx].list, list)
Paul Moore224dfbd2008-01-29 08:38:13 -0500147 if (node->nsec.family == family)
148 switch (family) {
149 case PF_INET:
150 if (node->nsec.addr.ipv4 == *(__be32 *)addr)
151 return node;
152 break;
153 case PF_INET6:
154 if (ipv6_addr_equal(&node->nsec.addr.ipv6,
155 addr))
156 return node;
157 break;
158 }
159
160 return NULL;
161}
162
163/**
164 * sel_netnode_insert - Insert a new node into the table
165 * @node: the new node record
166 *
167 * Description:
Paul Moorea639e7ca2008-04-25 15:03:34 -0400168 * Add a new node record to the network address hash table.
Paul Moore224dfbd2008-01-29 08:38:13 -0500169 *
170 */
Paul Moorea639e7ca2008-04-25 15:03:34 -0400171static void sel_netnode_insert(struct sel_netnode *node)
Paul Moore224dfbd2008-01-29 08:38:13 -0500172{
Paul Moorea639e7ca2008-04-25 15:03:34 -0400173 unsigned int idx;
Paul Moore224dfbd2008-01-29 08:38:13 -0500174
175 switch (node->nsec.family) {
176 case PF_INET:
177 idx = sel_netnode_hashfn_ipv4(node->nsec.addr.ipv4);
178 break;
179 case PF_INET6:
180 idx = sel_netnode_hashfn_ipv6(&node->nsec.addr.ipv6);
181 break;
182 default:
183 BUG();
184 }
Paul Moorea639e7ca2008-04-25 15:03:34 -0400185
Paul Moore224dfbd2008-01-29 08:38:13 -0500186 /* we need to impose a limit on the growth of the hash table so check
187 * this bucket to make sure it is within the specified bounds */
Paul Moorea639e7ca2008-04-25 15:03:34 -0400188 list_add_rcu(&node->list, &sel_netnode_hash[idx].list);
189 if (sel_netnode_hash[idx].size == SEL_NETNODE_HASH_BKT_LIMIT) {
190 struct sel_netnode *tail;
191 tail = list_entry(
192 rcu_dereference(sel_netnode_hash[idx].list.prev),
193 struct sel_netnode, list);
194 list_del_rcu(&tail->list);
195 call_rcu(&tail->rcu, sel_netnode_free);
196 } else
197 sel_netnode_hash[idx].size++;
Paul Moore224dfbd2008-01-29 08:38:13 -0500198}
199
200/**
201 * sel_netnode_sid_slow - Lookup the SID of a network address using the policy
202 * @addr: the IP address
203 * @family: the address family
204 * @sid: node SID
205 *
206 * Description:
207 * This function determines the SID of a network address by quering the
208 * security policy. The result is added to the network address table to
209 * speedup future queries. Returns zero on success, negative values on
210 * failure.
211 *
212 */
213static int sel_netnode_sid_slow(void *addr, u16 family, u32 *sid)
214{
Paul Moorea639e7ca2008-04-25 15:03:34 -0400215 int ret = -ENOMEM;
Paul Moore224dfbd2008-01-29 08:38:13 -0500216 struct sel_netnode *node;
217 struct sel_netnode *new = NULL;
218
219 spin_lock_bh(&sel_netnode_lock);
220 node = sel_netnode_find(addr, family);
221 if (node != NULL) {
222 *sid = node->nsec.sid;
Paul Moorea639e7ca2008-04-25 15:03:34 -0400223 spin_unlock_bh(&sel_netnode_lock);
224 return 0;
Paul Moore224dfbd2008-01-29 08:38:13 -0500225 }
226 new = kzalloc(sizeof(*new), GFP_ATOMIC);
Paul Moorea639e7ca2008-04-25 15:03:34 -0400227 if (new == NULL)
Paul Moore224dfbd2008-01-29 08:38:13 -0500228 goto out;
Paul Moore224dfbd2008-01-29 08:38:13 -0500229 switch (family) {
230 case PF_INET:
231 ret = security_node_sid(PF_INET,
Paul Moorea639e7ca2008-04-25 15:03:34 -0400232 addr, sizeof(struct in_addr), sid);
Paul Moore224dfbd2008-01-29 08:38:13 -0500233 new->nsec.addr.ipv4 = *(__be32 *)addr;
234 break;
235 case PF_INET6:
236 ret = security_node_sid(PF_INET6,
Paul Moorea639e7ca2008-04-25 15:03:34 -0400237 addr, sizeof(struct in6_addr), sid);
Paul Moore224dfbd2008-01-29 08:38:13 -0500238 ipv6_addr_copy(&new->nsec.addr.ipv6, addr);
239 break;
240 default:
241 BUG();
242 }
243 if (ret != 0)
244 goto out;
Paul Moorea639e7ca2008-04-25 15:03:34 -0400245
Paul Moore224dfbd2008-01-29 08:38:13 -0500246 new->nsec.family = family;
Paul Moorea639e7ca2008-04-25 15:03:34 -0400247 new->nsec.sid = *sid;
248 sel_netnode_insert(new);
Paul Moore224dfbd2008-01-29 08:38:13 -0500249
250out:
251 spin_unlock_bh(&sel_netnode_lock);
Paul Moore71f1cb02008-01-29 08:51:16 -0500252 if (unlikely(ret)) {
253 printk(KERN_WARNING
254 "SELinux: failure in sel_netnode_sid_slow(),"
255 " unable to determine network node label\n");
Paul Moore224dfbd2008-01-29 08:38:13 -0500256 kfree(new);
Paul Moore71f1cb02008-01-29 08:51:16 -0500257 }
Paul Moore224dfbd2008-01-29 08:38:13 -0500258 return ret;
259}
260
261/**
262 * sel_netnode_sid - Lookup the SID of a network address
263 * @addr: the IP address
264 * @family: the address family
265 * @sid: node SID
266 *
267 * Description:
268 * This function determines the SID of a network address using the fastest
269 * method possible. First the address table is queried, but if an entry
270 * can't be found then the policy is queried and the result is added to the
271 * table to speedup future queries. Returns zero on success, negative values
272 * on failure.
273 *
274 */
275int sel_netnode_sid(void *addr, u16 family, u32 *sid)
276{
277 struct sel_netnode *node;
278
279 rcu_read_lock();
280 node = sel_netnode_find(addr, family);
281 if (node != NULL) {
282 *sid = node->nsec.sid;
283 rcu_read_unlock();
284 return 0;
285 }
286 rcu_read_unlock();
287
288 return sel_netnode_sid_slow(addr, family, sid);
289}
290
291/**
292 * sel_netnode_flush - Flush the entire network address table
293 *
294 * Description:
295 * Remove all entries from the network address table.
296 *
297 */
298static void sel_netnode_flush(void)
299{
Paul Moorea639e7ca2008-04-25 15:03:34 -0400300 unsigned int idx;
301 struct sel_netnode *node, *node_tmp;
Paul Moore224dfbd2008-01-29 08:38:13 -0500302
303 spin_lock_bh(&sel_netnode_lock);
Paul Moorea639e7ca2008-04-25 15:03:34 -0400304 for (idx = 0; idx < SEL_NETNODE_HASH_SIZE; idx++) {
305 list_for_each_entry_safe(node, node_tmp,
306 &sel_netnode_hash[idx].list, list) {
307 list_del_rcu(&node->list);
308 call_rcu(&node->rcu, sel_netnode_free);
309 }
310 sel_netnode_hash[idx].size = 0;
311 }
Paul Moore224dfbd2008-01-29 08:38:13 -0500312 spin_unlock_bh(&sel_netnode_lock);
313}
314
315static int sel_netnode_avc_callback(u32 event, u32 ssid, u32 tsid,
316 u16 class, u32 perms, u32 *retained)
317{
318 if (event == AVC_CALLBACK_RESET) {
319 sel_netnode_flush();
320 synchronize_net();
321 }
322 return 0;
323}
324
325static __init int sel_netnode_init(void)
326{
327 int iter;
328 int ret;
329
330 if (!selinux_enabled)
331 return 0;
332
Paul Moorea639e7ca2008-04-25 15:03:34 -0400333 for (iter = 0; iter < SEL_NETNODE_HASH_SIZE; iter++) {
334 INIT_LIST_HEAD(&sel_netnode_hash[iter].list);
335 sel_netnode_hash[iter].size = 0;
336 }
Paul Moore224dfbd2008-01-29 08:38:13 -0500337
338 ret = avc_add_callback(sel_netnode_avc_callback, AVC_CALLBACK_RESET,
Eric Paris7b6b2392008-04-18 17:38:25 -0400339 SECSID_NULL, SECSID_NULL, SECCLASS_NULL, 0);
Paul Moore224dfbd2008-01-29 08:38:13 -0500340 if (ret != 0)
341 panic("avc_add_callback() failed, error %d\n", ret);
342
343 return ret;
344}
345
346__initcall(sel_netnode_init);