1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Network port table
4 *
5 * SELinux must keep a mapping of network ports to labels/SIDs. This
6 * mapping is maintained as part of the normal policy but a fast cache is
7 * needed to reduce the lookup overhead.
8 *
9 * Author: Paul Moore <paul@paul-moore.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 * (c) Copyright Hewlett-Packard Development Company, L.P., 2008
18 */
19
20 #include <linux/types.h>
21 #include <linux/rcupdate.h>
22 #include <linux/list.h>
23 #include <linux/slab.h>
24 #include <linux/spinlock.h>
25 #include <linux/in.h>
26 #include <linux/in6.h>
27 #include <linux/ip.h>
28 #include <linux/ipv6.h>
29 #include <net/ip.h>
30 #include <net/ipv6.h>
31
32 #include "netport.h"
33 #include "objsec.h"
34
35 #define SEL_NETPORT_HASH_SIZE 256
36 #define SEL_NETPORT_HASH_BKT_LIMIT 16
37
38 struct sel_netport_bkt {
39 int size;
40 struct list_head list;
41 };
42
43 struct sel_netport {
44 struct netport_security_struct psec;
45
46 struct list_head list;
47 struct rcu_head rcu;
48 };
49
50 /* NOTE: we are using a combined hash table for both IPv4 and IPv6, the reason
51 * for this is that I suspect most users will not make heavy use of both
52 * address families at the same time so one table will usually end up wasted,
53 * if this becomes a problem we can always add a hash table for each address
54 * family later */
55
56 static DEFINE_SPINLOCK(sel_netport_lock);
57 static struct sel_netport_bkt sel_netport_hash[SEL_NETPORT_HASH_SIZE];
58
59 /**
60 * sel_netport_hashfn - Hashing function for the port table
61 * @pnum: port number
62 *
63 * Description:
64 * This is the hashing function for the port table, it returns the bucket
65 * number for the given port.
66 *
67 */
sel_netport_hashfn(u16 pnum)68 static unsigned int sel_netport_hashfn(u16 pnum)
69 {
70 return (pnum & (SEL_NETPORT_HASH_SIZE - 1));
71 }
72
73 /**
74 * sel_netport_find - Search for a port record
75 * @protocol: protocol
76 * @pnum: port
77 *
78 * Description:
79 * Search the network port table and return the matching record. If an entry
80 * can not be found in the table return NULL.
81 *
82 */
sel_netport_find(u8 protocol,u16 pnum)83 static struct sel_netport *sel_netport_find(u8 protocol, u16 pnum)
84 {
85 unsigned int idx;
86 struct sel_netport *port;
87
88 idx = sel_netport_hashfn(pnum);
89 list_for_each_entry_rcu(port, &sel_netport_hash[idx].list, list)
90 if (port->psec.port == pnum && port->psec.protocol == protocol)
91 return port;
92
93 return NULL;
94 }
95
96 /**
97 * sel_netport_insert - Insert a new port into the table
98 * @port: the new port record
99 *
100 * Description:
101 * Add a new port record to the network address hash table.
102 *
103 */
sel_netport_insert(struct sel_netport * port)104 static void sel_netport_insert(struct sel_netport *port)
105 {
106 unsigned int idx;
107
108 /* we need to impose a limit on the growth of the hash table so check
109 * this bucket to make sure it is within the specified bounds */
110 idx = sel_netport_hashfn(port->psec.port);
111 list_add_rcu(&port->list, &sel_netport_hash[idx].list);
112 if (sel_netport_hash[idx].size == SEL_NETPORT_HASH_BKT_LIMIT) {
113 struct sel_netport *tail;
114 tail = list_entry(
115 rcu_dereference_protected(
116 list_tail_rcu(&sel_netport_hash[idx].list),
117 lockdep_is_held(&sel_netport_lock)),
118 struct sel_netport, list);
119 list_del_rcu(&tail->list);
120 kfree_rcu(tail, rcu);
121 } else
122 sel_netport_hash[idx].size++;
123 }
124
125 /**
126 * sel_netport_sid_slow - Lookup the SID of a network address using the policy
127 * @protocol: protocol
128 * @pnum: port
129 * @sid: port SID
130 *
131 * Description:
132 * This function determines the SID of a network port by querying the security
133 * policy. The result is added to the network port table to speedup future
134 * queries. Returns zero on success, negative values on failure.
135 *
136 */
sel_netport_sid_slow(u8 protocol,u16 pnum,u32 * sid)137 static int sel_netport_sid_slow(u8 protocol, u16 pnum, u32 *sid)
138 {
139 int ret;
140 struct sel_netport *port;
141 struct sel_netport *new;
142
143 spin_lock_bh(&sel_netport_lock);
144 port = sel_netport_find(protocol, pnum);
145 if (port != NULL) {
146 *sid = port->psec.sid;
147 spin_unlock_bh(&sel_netport_lock);
148 return 0;
149 }
150
151 ret = security_port_sid(protocol, pnum, sid);
152 if (ret != 0)
153 goto out;
154 new = kzalloc(sizeof(*new), GFP_ATOMIC);
155 if (new) {
156 new->psec.port = pnum;
157 new->psec.protocol = protocol;
158 new->psec.sid = *sid;
159 sel_netport_insert(new);
160 }
161
162 out:
163 spin_unlock_bh(&sel_netport_lock);
164 if (unlikely(ret))
165 pr_warn("SELinux: failure in %s(), unable to determine network port label\n",
166 __func__);
167 return ret;
168 }
169
170 /**
171 * sel_netport_sid - Lookup the SID of a network port
172 * @protocol: protocol
173 * @pnum: port
174 * @sid: port SID
175 *
176 * Description:
177 * This function determines the SID of a network port using the fastest method
178 * possible. First the port table is queried, but if an entry can't be found
179 * then the policy is queried and the result is added to the table to speedup
180 * future queries. Returns zero on success, negative values on failure.
181 *
182 */
sel_netport_sid(u8 protocol,u16 pnum,u32 * sid)183 int sel_netport_sid(u8 protocol, u16 pnum, u32 *sid)
184 {
185 struct sel_netport *port;
186
187 rcu_read_lock();
188 port = sel_netport_find(protocol, pnum);
189 if (port != NULL) {
190 *sid = port->psec.sid;
191 rcu_read_unlock();
192 return 0;
193 }
194 rcu_read_unlock();
195
196 return sel_netport_sid_slow(protocol, pnum, sid);
197 }
198
199 /**
200 * sel_netport_flush - Flush the entire network port table
201 *
202 * Description:
203 * Remove all entries from the network address table.
204 *
205 */
sel_netport_flush(void)206 void sel_netport_flush(void)
207 {
208 unsigned int idx;
209 struct sel_netport *port, *port_tmp;
210
211 spin_lock_bh(&sel_netport_lock);
212 for (idx = 0; idx < SEL_NETPORT_HASH_SIZE; idx++) {
213 list_for_each_entry_safe(port, port_tmp,
214 &sel_netport_hash[idx].list, list) {
215 list_del_rcu(&port->list);
216 kfree_rcu(port, rcu);
217 }
218 sel_netport_hash[idx].size = 0;
219 }
220 spin_unlock_bh(&sel_netport_lock);
221 }
222
sel_netport_init(void)223 static __init int sel_netport_init(void)
224 {
225 int iter;
226
227 if (!selinux_enabled_boot)
228 return 0;
229
230 for (iter = 0; iter < SEL_NETPORT_HASH_SIZE; iter++) {
231 INIT_LIST_HEAD(&sel_netport_hash[iter].list);
232 sel_netport_hash[iter].size = 0;
233 }
234
235 return 0;
236 }
237
238 __initcall(sel_netport_init);
239