blob: fe7fba67f19f0dd2c0b2c96c5a736ecb15bd362d [file] [log] [blame]
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>
33#include <linux/spinlock.h>
34#include <linux/in.h>
35#include <linux/in6.h>
36#include <linux/ip.h>
37#include <linux/ipv6.h>
38#include <net/ip.h>
39#include <net/ipv6.h>
James Morris27cc2a62008-04-14 15:09:53 +100040
41#include "netport.h"
42#include "objsec.h"
43
44#define SEL_NETPORT_HASH_SIZE 256
45#define SEL_NETPORT_HASH_BKT_LIMIT 16
46
47struct sel_netport_bkt {
48 int size;
49 struct list_head list;
50};
51
52struct sel_netport {
53 struct netport_security_struct psec;
54
55 struct list_head list;
56 struct rcu_head rcu;
57};
58
59/* NOTE: we are using a combined hash table for both IPv4 and IPv6, the reason
60 * for this is that I suspect most users will not make heavy use of both
61 * address families at the same time so one table will usually end up wasted,
62 * if this becomes a problem we can always add a hash table for each address
63 * family later */
64
65static LIST_HEAD(sel_netport_list);
66static DEFINE_SPINLOCK(sel_netport_lock);
67static struct sel_netport_bkt sel_netport_hash[SEL_NETPORT_HASH_SIZE];
68
69/**
70 * sel_netport_free - Frees a port entry
71 * @p: the entry's RCU field
72 *
73 * Description:
74 * This function is designed to be used as a callback to the call_rcu()
75 * function so that memory allocated to a hash table port entry can be
76 * released safely.
77 *
78 */
79static void sel_netport_free(struct rcu_head *p)
80{
81 struct sel_netport *port = container_of(p, struct sel_netport, rcu);
82 kfree(port);
83}
84
85/**
86 * sel_netport_hashfn - Hashing function for the port table
87 * @pnum: port number
88 *
89 * Description:
90 * This is the hashing function for the port table, it returns the bucket
91 * number for the given port.
92 *
93 */
94static unsigned int sel_netport_hashfn(u16 pnum)
95{
96 return (pnum & (SEL_NETPORT_HASH_SIZE - 1));
97}
98
99/**
100 * sel_netport_find - Search for a port record
101 * @protocol: protocol
102 * @port: pnum
103 *
104 * Description:
105 * Search the network port table and return the matching record. If an entry
106 * can not be found in the table return NULL.
107 *
108 */
109static struct sel_netport *sel_netport_find(u8 protocol, u16 pnum)
110{
111 unsigned int idx;
112 struct sel_netport *port;
113
114 idx = sel_netport_hashfn(pnum);
115 list_for_each_entry_rcu(port, &sel_netport_hash[idx].list, list)
Paul Moorec9b7b972008-04-25 15:03:39 -0400116 if (port->psec.port == pnum && port->psec.protocol == protocol)
James Morris27cc2a62008-04-14 15:09:53 +1000117 return port;
118
119 return NULL;
120}
121
122/**
123 * sel_netport_insert - Insert a new port into the table
124 * @port: the new port record
125 *
126 * Description:
Paul Moorec9b7b972008-04-25 15:03:39 -0400127 * Add a new port record to the network address hash table.
James Morris27cc2a62008-04-14 15:09:53 +1000128 *
129 */
Paul Moorec9b7b972008-04-25 15:03:39 -0400130static void sel_netport_insert(struct sel_netport *port)
James Morris27cc2a62008-04-14 15:09:53 +1000131{
132 unsigned int idx;
133
134 /* we need to impose a limit on the growth of the hash table so check
135 * this bucket to make sure it is within the specified bounds */
136 idx = sel_netport_hashfn(port->psec.port);
137 list_add_rcu(&port->list, &sel_netport_hash[idx].list);
138 if (sel_netport_hash[idx].size == SEL_NETPORT_HASH_BKT_LIMIT) {
139 struct sel_netport *tail;
Paul Moorec9b7b972008-04-25 15:03:39 -0400140 tail = list_entry(
141 rcu_dereference(sel_netport_hash[idx].list.prev),
142 struct sel_netport, list);
143 list_del_rcu(&tail->list);
James Morris27cc2a62008-04-14 15:09:53 +1000144 call_rcu(&tail->rcu, sel_netport_free);
145 } else
146 sel_netport_hash[idx].size++;
James Morris27cc2a62008-04-14 15:09:53 +1000147}
148
149/**
150 * sel_netport_sid_slow - Lookup the SID of a network address using the policy
151 * @protocol: protocol
152 * @pnum: port
153 * @sid: port SID
154 *
155 * Description:
156 * This function determines the SID of a network port by quering the security
157 * policy. The result is added to the network port table to speedup future
158 * queries. Returns zero on success, negative values on failure.
159 *
160 */
161static int sel_netport_sid_slow(u8 protocol, u16 pnum, u32 *sid)
162{
Paul Moorec9b7b972008-04-25 15:03:39 -0400163 int ret = -ENOMEM;
James Morris27cc2a62008-04-14 15:09:53 +1000164 struct sel_netport *port;
165 struct sel_netport *new = NULL;
166
167 spin_lock_bh(&sel_netport_lock);
168 port = sel_netport_find(protocol, pnum);
169 if (port != NULL) {
170 *sid = port->psec.sid;
Paul Moorec9b7b972008-04-25 15:03:39 -0400171 spin_unlock_bh(&sel_netport_lock);
172 return 0;
James Morris27cc2a62008-04-14 15:09:53 +1000173 }
174 new = kzalloc(sizeof(*new), GFP_ATOMIC);
Paul Moorec9b7b972008-04-25 15:03:39 -0400175 if (new == NULL)
James Morris27cc2a62008-04-14 15:09:53 +1000176 goto out;
Paul Moorec9b7b972008-04-25 15:03:39 -0400177 ret = security_port_sid(protocol, pnum, sid);
James Morris27cc2a62008-04-14 15:09:53 +1000178 if (ret != 0)
179 goto out;
Paul Moorec9b7b972008-04-25 15:03:39 -0400180
James Morris27cc2a62008-04-14 15:09:53 +1000181 new->psec.port = pnum;
182 new->psec.protocol = protocol;
Paul Moorec9b7b972008-04-25 15:03:39 -0400183 new->psec.sid = *sid;
184 sel_netport_insert(new);
James Morris27cc2a62008-04-14 15:09:53 +1000185
186out:
187 spin_unlock_bh(&sel_netport_lock);
188 if (unlikely(ret)) {
189 printk(KERN_WARNING
190 "SELinux: failure in sel_netport_sid_slow(),"
191 " unable to determine network port label\n");
192 kfree(new);
193 }
194 return ret;
195}
196
197/**
198 * sel_netport_sid - Lookup the SID of a network port
199 * @protocol: protocol
200 * @pnum: port
201 * @sid: port SID
202 *
203 * Description:
204 * This function determines the SID of a network port using the fastest method
205 * possible. First the port table is queried, but if an entry can't be found
206 * then the policy is queried and the result is added to the table to speedup
207 * future queries. Returns zero on success, negative values on failure.
208 *
209 */
210int sel_netport_sid(u8 protocol, u16 pnum, u32 *sid)
211{
212 struct sel_netport *port;
213
214 rcu_read_lock();
215 port = sel_netport_find(protocol, pnum);
216 if (port != NULL) {
217 *sid = port->psec.sid;
218 rcu_read_unlock();
219 return 0;
220 }
221 rcu_read_unlock();
222
223 return sel_netport_sid_slow(protocol, pnum, sid);
224}
225
226/**
227 * sel_netport_flush - Flush the entire network port table
228 *
229 * Description:
230 * Remove all entries from the network address table.
231 *
232 */
233static void sel_netport_flush(void)
234{
235 unsigned int idx;
Paul Moorec9b7b972008-04-25 15:03:39 -0400236 struct sel_netport *port, *port_tmp;
James Morris27cc2a62008-04-14 15:09:53 +1000237
238 spin_lock_bh(&sel_netport_lock);
239 for (idx = 0; idx < SEL_NETPORT_HASH_SIZE; idx++) {
Paul Moorec9b7b972008-04-25 15:03:39 -0400240 list_for_each_entry_safe(port, port_tmp,
241 &sel_netport_hash[idx].list, list) {
James Morris27cc2a62008-04-14 15:09:53 +1000242 list_del_rcu(&port->list);
243 call_rcu(&port->rcu, sel_netport_free);
244 }
245 sel_netport_hash[idx].size = 0;
246 }
247 spin_unlock_bh(&sel_netport_lock);
248}
249
250static int sel_netport_avc_callback(u32 event, u32 ssid, u32 tsid,
251 u16 class, u32 perms, u32 *retained)
252{
253 if (event == AVC_CALLBACK_RESET) {
254 sel_netport_flush();
255 synchronize_net();
256 }
257 return 0;
258}
259
260static __init int sel_netport_init(void)
261{
262 int iter;
263 int ret;
264
265 if (!selinux_enabled)
266 return 0;
267
268 for (iter = 0; iter < SEL_NETPORT_HASH_SIZE; iter++) {
269 INIT_LIST_HEAD(&sel_netport_hash[iter].list);
270 sel_netport_hash[iter].size = 0;
271 }
272
273 ret = avc_add_callback(sel_netport_avc_callback, AVC_CALLBACK_RESET,
Eric Parisf5269712008-05-14 11:27:45 -0400274 SECSID_NULL, SECSID_NULL, SECCLASS_NULL, 0);
James Morris27cc2a62008-04-14 15:09:53 +1000275 if (ret != 0)
276 panic("avc_add_callback() failed, error %d\n", ret);
277
278 return ret;
279}
280
281__initcall(sel_netport_init);