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James Morris27cc2a62008-04-14 15:09:53 +10001/*
2 * Network port table
3 *
4 * SELinux must keep a mapping of network ports 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.
7 *
8 * Author: Paul Moore <paul.moore@hp.com>
9 *
10 * This code is heavily based on the "netif" concept originally developed by
11 * James Morris <jmorris@redhat.com>
12 * (see security/selinux/netif.c for more information)
13 *
14 */
15
16/*
17 * (c) Copyright Hewlett-Packard Development Company, L.P., 2008
18 *
19 * This program is free software: you can redistribute it and/or modify
20 * it under the terms of version 2 of the GNU General Public License as
21 * published by the Free Software Foundation.
22 *
23 * This program is distributed in the hope that it will be useful,
24 * but WITHOUT ANY WARRANTY; without even the implied warranty of
25 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
26 * GNU General Public License for more details.
27 *
28 */
29
30#include <linux/types.h>
31#include <linux/rcupdate.h>
32#include <linux/list.h>
Tejun Heo5a0e3ad2010-03-24 17:04:11 +090033#include <linux/slab.h>
James Morris27cc2a62008-04-14 15:09:53 +100034#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>
James Morris27cc2a62008-04-14 15:09:53 +100041
42#include "netport.h"
43#include "objsec.h"
44
45#define SEL_NETPORT_HASH_SIZE 256
46#define SEL_NETPORT_HASH_BKT_LIMIT 16
47
48struct sel_netport_bkt {
49 int size;
50 struct list_head list;
51};
52
53struct sel_netport {
54 struct netport_security_struct psec;
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_netport_list);
67static DEFINE_SPINLOCK(sel_netport_lock);
68static struct sel_netport_bkt sel_netport_hash[SEL_NETPORT_HASH_SIZE];
69
70/**
71 * sel_netport_free - Frees a port 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 port entry can be
77 * released safely.
78 *
79 */
80static void sel_netport_free(struct rcu_head *p)
81{
82 struct sel_netport *port = container_of(p, struct sel_netport, rcu);
83 kfree(port);
84}
85
86/**
87 * sel_netport_hashfn - Hashing function for the port table
88 * @pnum: port number
89 *
90 * Description:
91 * This is the hashing function for the port table, it returns the bucket
92 * number for the given port.
93 *
94 */
95static unsigned int sel_netport_hashfn(u16 pnum)
96{
97 return (pnum & (SEL_NETPORT_HASH_SIZE - 1));
98}
99
100/**
101 * sel_netport_find - Search for a port record
102 * @protocol: protocol
103 * @port: pnum
104 *
105 * Description:
106 * Search the network port table and return the matching record. If an entry
107 * can not be found in the table return NULL.
108 *
109 */
110static struct sel_netport *sel_netport_find(u8 protocol, u16 pnum)
111{
112 unsigned int idx;
113 struct sel_netport *port;
114
115 idx = sel_netport_hashfn(pnum);
116 list_for_each_entry_rcu(port, &sel_netport_hash[idx].list, list)
Paul Moorec9b7b972008-04-25 15:03:39 -0400117 if (port->psec.port == pnum && port->psec.protocol == protocol)
James Morris27cc2a62008-04-14 15:09:53 +1000118 return port;
119
120 return NULL;
121}
122
123/**
124 * sel_netport_insert - Insert a new port into the table
125 * @port: the new port record
126 *
127 * Description:
Paul Moorec9b7b972008-04-25 15:03:39 -0400128 * Add a new port record to the network address hash table.
James Morris27cc2a62008-04-14 15:09:53 +1000129 *
130 */
Paul Moorec9b7b972008-04-25 15:03:39 -0400131static void sel_netport_insert(struct sel_netport *port)
James Morris27cc2a62008-04-14 15:09:53 +1000132{
133 unsigned int idx;
134
135 /* we need to impose a limit on the growth of the hash table so check
136 * this bucket to make sure it is within the specified bounds */
137 idx = sel_netport_hashfn(port->psec.port);
138 list_add_rcu(&port->list, &sel_netport_hash[idx].list);
139 if (sel_netport_hash[idx].size == SEL_NETPORT_HASH_BKT_LIMIT) {
140 struct sel_netport *tail;
Paul Moorec9b7b972008-04-25 15:03:39 -0400141 tail = list_entry(
142 rcu_dereference(sel_netport_hash[idx].list.prev),
143 struct sel_netport, list);
144 list_del_rcu(&tail->list);
James Morris27cc2a62008-04-14 15:09:53 +1000145 call_rcu(&tail->rcu, sel_netport_free);
146 } else
147 sel_netport_hash[idx].size++;
James Morris27cc2a62008-04-14 15:09:53 +1000148}
149
150/**
151 * sel_netport_sid_slow - Lookup the SID of a network address using the policy
152 * @protocol: protocol
153 * @pnum: port
154 * @sid: port SID
155 *
156 * Description:
157 * This function determines the SID of a network port by quering the security
158 * policy. The result is added to the network port table to speedup future
159 * queries. Returns zero on success, negative values on failure.
160 *
161 */
162static int sel_netport_sid_slow(u8 protocol, u16 pnum, u32 *sid)
163{
Paul Moorec9b7b972008-04-25 15:03:39 -0400164 int ret = -ENOMEM;
James Morris27cc2a62008-04-14 15:09:53 +1000165 struct sel_netport *port;
166 struct sel_netport *new = NULL;
167
168 spin_lock_bh(&sel_netport_lock);
169 port = sel_netport_find(protocol, pnum);
170 if (port != NULL) {
171 *sid = port->psec.sid;
Paul Moorec9b7b972008-04-25 15:03:39 -0400172 spin_unlock_bh(&sel_netport_lock);
173 return 0;
James Morris27cc2a62008-04-14 15:09:53 +1000174 }
175 new = kzalloc(sizeof(*new), GFP_ATOMIC);
Paul Moorec9b7b972008-04-25 15:03:39 -0400176 if (new == NULL)
James Morris27cc2a62008-04-14 15:09:53 +1000177 goto out;
Paul Moorec9b7b972008-04-25 15:03:39 -0400178 ret = security_port_sid(protocol, pnum, sid);
James Morris27cc2a62008-04-14 15:09:53 +1000179 if (ret != 0)
180 goto out;
Paul Moorec9b7b972008-04-25 15:03:39 -0400181
James Morris27cc2a62008-04-14 15:09:53 +1000182 new->psec.port = pnum;
183 new->psec.protocol = protocol;
Paul Moorec9b7b972008-04-25 15:03:39 -0400184 new->psec.sid = *sid;
185 sel_netport_insert(new);
James Morris27cc2a62008-04-14 15:09:53 +1000186
187out:
188 spin_unlock_bh(&sel_netport_lock);
189 if (unlikely(ret)) {
190 printk(KERN_WARNING
191 "SELinux: failure in sel_netport_sid_slow(),"
192 " unable to determine network port label\n");
193 kfree(new);
194 }
195 return ret;
196}
197
198/**
199 * sel_netport_sid - Lookup the SID of a network port
200 * @protocol: protocol
201 * @pnum: port
202 * @sid: port SID
203 *
204 * Description:
205 * This function determines the SID of a network port using the fastest method
206 * possible. First the port table is queried, but if an entry can't be found
207 * then the policy is queried and the result is added to the table to speedup
208 * future queries. Returns zero on success, negative values on failure.
209 *
210 */
211int sel_netport_sid(u8 protocol, u16 pnum, u32 *sid)
212{
213 struct sel_netport *port;
214
215 rcu_read_lock();
216 port = sel_netport_find(protocol, pnum);
217 if (port != NULL) {
218 *sid = port->psec.sid;
219 rcu_read_unlock();
220 return 0;
221 }
222 rcu_read_unlock();
223
224 return sel_netport_sid_slow(protocol, pnum, sid);
225}
226
227/**
228 * sel_netport_flush - Flush the entire network port table
229 *
230 * Description:
231 * Remove all entries from the network address table.
232 *
233 */
234static void sel_netport_flush(void)
235{
236 unsigned int idx;
Paul Moorec9b7b972008-04-25 15:03:39 -0400237 struct sel_netport *port, *port_tmp;
James Morris27cc2a62008-04-14 15:09:53 +1000238
239 spin_lock_bh(&sel_netport_lock);
240 for (idx = 0; idx < SEL_NETPORT_HASH_SIZE; idx++) {
Paul Moorec9b7b972008-04-25 15:03:39 -0400241 list_for_each_entry_safe(port, port_tmp,
242 &sel_netport_hash[idx].list, list) {
James Morris27cc2a62008-04-14 15:09:53 +1000243 list_del_rcu(&port->list);
244 call_rcu(&port->rcu, sel_netport_free);
245 }
246 sel_netport_hash[idx].size = 0;
247 }
248 spin_unlock_bh(&sel_netport_lock);
249}
250
251static int sel_netport_avc_callback(u32 event, u32 ssid, u32 tsid,
252 u16 class, u32 perms, u32 *retained)
253{
254 if (event == AVC_CALLBACK_RESET) {
255 sel_netport_flush();
256 synchronize_net();
257 }
258 return 0;
259}
260
261static __init int sel_netport_init(void)
262{
263 int iter;
264 int ret;
265
266 if (!selinux_enabled)
267 return 0;
268
269 for (iter = 0; iter < SEL_NETPORT_HASH_SIZE; iter++) {
270 INIT_LIST_HEAD(&sel_netport_hash[iter].list);
271 sel_netport_hash[iter].size = 0;
272 }
273
274 ret = avc_add_callback(sel_netport_avc_callback, AVC_CALLBACK_RESET,
Eric Parisf5269712008-05-14 11:27:45 -0400275 SECSID_NULL, SECSID_NULL, SECCLASS_NULL, 0);
James Morris27cc2a62008-04-14 15:09:53 +1000276 if (ret != 0)
277 panic("avc_add_callback() failed, error %d\n", ret);
278
279 return ret;
280}
281
282__initcall(sel_netport_init);