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27cc2a6e JM |
1 | /* |
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> | |
40 | #include <asm/bug.h> | |
41 | ||
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 | ||
48 | struct sel_netport_bkt { | |
49 | int size; | |
50 | struct list_head list; | |
51 | }; | |
52 | ||
53 | struct 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 | ||
66 | static LIST_HEAD(sel_netport_list); | |
67 | static DEFINE_SPINLOCK(sel_netport_lock); | |
68 | static 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 | */ | |
80 | static 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 | */ | |
95 | static 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 | */ | |
110 | static 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) | |
117 | if (port->psec.port == pnum && | |
118 | port->psec.protocol == protocol) | |
119 | return port; | |
120 | ||
121 | return NULL; | |
122 | } | |
123 | ||
124 | /** | |
125 | * sel_netport_insert - Insert a new port into the table | |
126 | * @port: the new port record | |
127 | * | |
128 | * Description: | |
129 | * Add a new port record to the network address hash table. Returns zero on | |
130 | * success, negative values on failure. | |
131 | * | |
132 | */ | |
133 | static int sel_netport_insert(struct sel_netport *port) | |
134 | { | |
135 | unsigned int idx; | |
136 | ||
137 | /* we need to impose a limit on the growth of the hash table so check | |
138 | * this bucket to make sure it is within the specified bounds */ | |
139 | idx = sel_netport_hashfn(port->psec.port); | |
140 | list_add_rcu(&port->list, &sel_netport_hash[idx].list); | |
141 | if (sel_netport_hash[idx].size == SEL_NETPORT_HASH_BKT_LIMIT) { | |
142 | struct sel_netport *tail; | |
143 | tail = list_entry(port->list.prev, struct sel_netport, list); | |
144 | list_del_rcu(port->list.prev); | |
145 | call_rcu(&tail->rcu, sel_netport_free); | |
146 | } else | |
147 | sel_netport_hash[idx].size++; | |
148 | ||
149 | return 0; | |
150 | } | |
151 | ||
152 | /** | |
153 | * sel_netport_sid_slow - Lookup the SID of a network address using the policy | |
154 | * @protocol: protocol | |
155 | * @pnum: port | |
156 | * @sid: port SID | |
157 | * | |
158 | * Description: | |
159 | * This function determines the SID of a network port by quering the security | |
160 | * policy. The result is added to the network port table to speedup future | |
161 | * queries. Returns zero on success, negative values on failure. | |
162 | * | |
163 | */ | |
164 | static int sel_netport_sid_slow(u8 protocol, u16 pnum, u32 *sid) | |
165 | { | |
166 | int ret; | |
167 | struct sel_netport *port; | |
168 | struct sel_netport *new = NULL; | |
169 | ||
170 | spin_lock_bh(&sel_netport_lock); | |
171 | port = sel_netport_find(protocol, pnum); | |
172 | if (port != NULL) { | |
173 | *sid = port->psec.sid; | |
174 | ret = 0; | |
175 | goto out; | |
176 | } | |
177 | new = kzalloc(sizeof(*new), GFP_ATOMIC); | |
178 | if (new == NULL) { | |
179 | ret = -ENOMEM; | |
180 | goto out; | |
181 | } | |
182 | ret = security_port_sid(protocol, pnum, &new->psec.sid); | |
183 | if (ret != 0) | |
184 | goto out; | |
185 | new->psec.port = pnum; | |
186 | new->psec.protocol = protocol; | |
187 | ret = sel_netport_insert(new); | |
188 | if (ret != 0) | |
189 | goto out; | |
190 | *sid = new->psec.sid; | |
191 | ||
192 | out: | |
193 | spin_unlock_bh(&sel_netport_lock); | |
194 | if (unlikely(ret)) { | |
195 | printk(KERN_WARNING | |
196 | "SELinux: failure in sel_netport_sid_slow()," | |
197 | " unable to determine network port label\n"); | |
198 | kfree(new); | |
199 | } | |
200 | return ret; | |
201 | } | |
202 | ||
203 | /** | |
204 | * sel_netport_sid - Lookup the SID of a network port | |
205 | * @protocol: protocol | |
206 | * @pnum: port | |
207 | * @sid: port SID | |
208 | * | |
209 | * Description: | |
210 | * This function determines the SID of a network port using the fastest method | |
211 | * possible. First the port table is queried, but if an entry can't be found | |
212 | * then the policy is queried and the result is added to the table to speedup | |
213 | * future queries. Returns zero on success, negative values on failure. | |
214 | * | |
215 | */ | |
216 | int sel_netport_sid(u8 protocol, u16 pnum, u32 *sid) | |
217 | { | |
218 | struct sel_netport *port; | |
219 | ||
220 | rcu_read_lock(); | |
221 | port = sel_netport_find(protocol, pnum); | |
222 | if (port != NULL) { | |
223 | *sid = port->psec.sid; | |
224 | rcu_read_unlock(); | |
225 | return 0; | |
226 | } | |
227 | rcu_read_unlock(); | |
228 | ||
229 | return sel_netport_sid_slow(protocol, pnum, sid); | |
230 | } | |
231 | ||
232 | /** | |
233 | * sel_netport_flush - Flush the entire network port table | |
234 | * | |
235 | * Description: | |
236 | * Remove all entries from the network address table. | |
237 | * | |
238 | */ | |
239 | static void sel_netport_flush(void) | |
240 | { | |
241 | unsigned int idx; | |
242 | struct sel_netport *port; | |
243 | ||
244 | spin_lock_bh(&sel_netport_lock); | |
245 | for (idx = 0; idx < SEL_NETPORT_HASH_SIZE; idx++) { | |
246 | list_for_each_entry(port, &sel_netport_hash[idx].list, list) { | |
247 | list_del_rcu(&port->list); | |
248 | call_rcu(&port->rcu, sel_netport_free); | |
249 | } | |
250 | sel_netport_hash[idx].size = 0; | |
251 | } | |
252 | spin_unlock_bh(&sel_netport_lock); | |
253 | } | |
254 | ||
255 | static int sel_netport_avc_callback(u32 event, u32 ssid, u32 tsid, | |
256 | u16 class, u32 perms, u32 *retained) | |
257 | { | |
258 | if (event == AVC_CALLBACK_RESET) { | |
259 | sel_netport_flush(); | |
260 | synchronize_net(); | |
261 | } | |
262 | return 0; | |
263 | } | |
264 | ||
265 | static __init int sel_netport_init(void) | |
266 | { | |
267 | int iter; | |
268 | int ret; | |
269 | ||
270 | if (!selinux_enabled) | |
271 | return 0; | |
272 | ||
273 | for (iter = 0; iter < SEL_NETPORT_HASH_SIZE; iter++) { | |
274 | INIT_LIST_HEAD(&sel_netport_hash[iter].list); | |
275 | sel_netport_hash[iter].size = 0; | |
276 | } | |
277 | ||
278 | ret = avc_add_callback(sel_netport_avc_callback, AVC_CALLBACK_RESET, | |
279 | SECSID_NULL, SECSID_NULL, SECCLASS_NULL, 0); | |
280 | if (ret != 0) | |
281 | panic("avc_add_callback() failed, error %d\n", ret); | |
282 | ||
283 | return ret; | |
284 | } | |
285 | ||
286 | __initcall(sel_netport_init); |