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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> | |
27cc2a6e JM |
40 | |
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 | ||
47 | struct sel_netport_bkt { | |
48 | int size; | |
49 | struct list_head list; | |
50 | }; | |
51 | ||
52 | struct 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 | ||
65 | static LIST_HEAD(sel_netport_list); | |
66 | static DEFINE_SPINLOCK(sel_netport_lock); | |
67 | static 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 | */ | |
79 | static 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 | */ | |
94 | static 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 | */ | |
109 | static 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) | |
c9b7b979 | 116 | if (port->psec.port == pnum && port->psec.protocol == protocol) |
27cc2a6e JM |
117 | 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: | |
c9b7b979 | 127 | * Add a new port record to the network address hash table. |
27cc2a6e JM |
128 | * |
129 | */ | |
c9b7b979 | 130 | static void sel_netport_insert(struct sel_netport *port) |
27cc2a6e JM |
131 | { |
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; | |
c9b7b979 PM |
140 | tail = list_entry( |
141 | rcu_dereference(sel_netport_hash[idx].list.prev), | |
142 | struct sel_netport, list); | |
143 | list_del_rcu(&tail->list); | |
27cc2a6e JM |
144 | call_rcu(&tail->rcu, sel_netport_free); |
145 | } else | |
146 | sel_netport_hash[idx].size++; | |
27cc2a6e JM |
147 | } |
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 | */ | |
161 | static int sel_netport_sid_slow(u8 protocol, u16 pnum, u32 *sid) | |
162 | { | |
c9b7b979 | 163 | int ret = -ENOMEM; |
27cc2a6e JM |
164 | 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; | |
c9b7b979 PM |
171 | spin_unlock_bh(&sel_netport_lock); |
172 | return 0; | |
27cc2a6e JM |
173 | } |
174 | new = kzalloc(sizeof(*new), GFP_ATOMIC); | |
c9b7b979 | 175 | if (new == NULL) |
27cc2a6e | 176 | goto out; |
c9b7b979 | 177 | ret = security_port_sid(protocol, pnum, sid); |
27cc2a6e JM |
178 | if (ret != 0) |
179 | goto out; | |
c9b7b979 | 180 | |
27cc2a6e JM |
181 | new->psec.port = pnum; |
182 | new->psec.protocol = protocol; | |
c9b7b979 PM |
183 | new->psec.sid = *sid; |
184 | sel_netport_insert(new); | |
27cc2a6e JM |
185 | |
186 | out: | |
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 | */ | |
210 | int 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 | */ | |
233 | static void sel_netport_flush(void) | |
234 | { | |
235 | unsigned int idx; | |
c9b7b979 | 236 | struct sel_netport *port, *port_tmp; |
27cc2a6e JM |
237 | |
238 | spin_lock_bh(&sel_netport_lock); | |
239 | for (idx = 0; idx < SEL_NETPORT_HASH_SIZE; idx++) { | |
c9b7b979 PM |
240 | list_for_each_entry_safe(port, port_tmp, |
241 | &sel_netport_hash[idx].list, list) { | |
27cc2a6e JM |
242 | 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 | ||
250 | static 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 | ||
260 | static __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, | |
f5269710 | 274 | SECSID_NULL, SECSID_NULL, SECCLASS_NULL, 0); |
27cc2a6e JM |
275 | if (ret != 0) |
276 | panic("avc_add_callback() failed, error %d\n", ret); | |
277 | ||
278 | return ret; | |
279 | } | |
280 | ||
281 | __initcall(sel_netport_init); |