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 "initcalls.h"
33 #include "netport.h"
34 #include "objsec.h"
35
36 #define SEL_NETPORT_HASH_SIZE 256
37 #define SEL_NETPORT_HASH_BKT_LIMIT 16
38
39 struct sel_netport_bkt {
40 int size;
41 struct list_head list;
42 };
43
44 struct sel_netport {
45 struct netport_security_struct psec;
46
47 struct list_head list;
48 struct rcu_head rcu;
49 };
50
51 static DEFINE_SPINLOCK(sel_netport_lock);
52 static struct sel_netport_bkt sel_netport_hash[SEL_NETPORT_HASH_SIZE];
53
54 /**
55 * sel_netport_hashfn - Hashing function for the port table
56 * @pnum: port number
57 *
58 * Description:
59 * This is the hashing function for the port table, it returns the bucket
60 * number for the given port.
61 *
62 */
sel_netport_hashfn(u16 pnum)63 static unsigned int sel_netport_hashfn(u16 pnum)
64 {
65 return (pnum & (SEL_NETPORT_HASH_SIZE - 1));
66 }
67
68 /**
69 * sel_netport_find - Search for a port record
70 * @protocol: protocol
71 * @pnum: port
72 *
73 * Description:
74 * Search the network port table and return the matching record. If an entry
75 * can not be found in the table return NULL.
76 *
77 */
sel_netport_find(u8 protocol,u16 pnum)78 static struct sel_netport *sel_netport_find(u8 protocol, u16 pnum)
79 {
80 unsigned int idx;
81 struct sel_netport *port;
82
83 idx = sel_netport_hashfn(pnum);
84 list_for_each_entry_rcu(port, &sel_netport_hash[idx].list, list)
85 if (port->psec.port == pnum && port->psec.protocol == protocol)
86 return port;
87
88 return NULL;
89 }
90
91 /**
92 * sel_netport_insert - Insert a new port into the table
93 * @port: the new port record
94 *
95 * Description:
96 * Add a new port record to the network address hash table.
97 *
98 */
sel_netport_insert(struct sel_netport * port)99 static void sel_netport_insert(struct sel_netport *port)
100 {
101 unsigned int idx;
102
103 /* we need to impose a limit on the growth of the hash table so check
104 * this bucket to make sure it is within the specified bounds */
105 idx = sel_netport_hashfn(port->psec.port);
106 list_add_rcu(&port->list, &sel_netport_hash[idx].list);
107 if (sel_netport_hash[idx].size == SEL_NETPORT_HASH_BKT_LIMIT) {
108 struct sel_netport *tail;
109 tail = list_entry(
110 rcu_dereference_protected(
111 list_tail_rcu(&sel_netport_hash[idx].list),
112 lockdep_is_held(&sel_netport_lock)),
113 struct sel_netport, list);
114 list_del_rcu(&tail->list);
115 kfree_rcu(tail, rcu);
116 } else
117 sel_netport_hash[idx].size++;
118 }
119
120 /**
121 * sel_netport_sid_slow - Lookup the SID of a network address using the policy
122 * @protocol: protocol
123 * @pnum: port
124 * @sid: port SID
125 *
126 * Description:
127 * This function determines the SID of a network port by querying the security
128 * policy. The result is added to the network port table to speedup future
129 * queries. Returns zero on success, negative values on failure.
130 *
131 */
sel_netport_sid_slow(u8 protocol,u16 pnum,u32 * sid)132 static int sel_netport_sid_slow(u8 protocol, u16 pnum, u32 *sid)
133 {
134 int ret;
135 struct sel_netport *port;
136 struct sel_netport *new;
137
138 spin_lock_bh(&sel_netport_lock);
139 port = sel_netport_find(protocol, pnum);
140 if (port != NULL) {
141 *sid = port->psec.sid;
142 spin_unlock_bh(&sel_netport_lock);
143 return 0;
144 }
145
146 ret = security_port_sid(protocol, pnum, sid);
147 if (ret != 0)
148 goto out;
149
150 /* If this memory allocation fails still return 0. The SID
151 * is valid, it just won't be added to the cache.
152 */
153 new = kmalloc(sizeof(*new), GFP_ATOMIC);
154 if (new) {
155 new->psec.port = pnum;
156 new->psec.protocol = protocol;
157 new->psec.sid = *sid;
158 sel_netport_insert(new);
159 }
160
161 out:
162 spin_unlock_bh(&sel_netport_lock);
163 if (unlikely(ret))
164 pr_warn("SELinux: failure in %s(), unable to determine network port label\n",
165 __func__);
166 return ret;
167 }
168
169 /**
170 * sel_netport_sid - Lookup the SID of a network port
171 * @protocol: protocol
172 * @pnum: port
173 * @sid: port SID
174 *
175 * Description:
176 * This function determines the SID of a network port using the fastest method
177 * possible. First the port table is queried, but if an entry can't be found
178 * then the policy is queried and the result is added to the table to speedup
179 * future queries. Returns zero on success, negative values on failure.
180 *
181 */
sel_netport_sid(u8 protocol,u16 pnum,u32 * sid)182 int sel_netport_sid(u8 protocol, u16 pnum, u32 *sid)
183 {
184 struct sel_netport *port;
185
186 rcu_read_lock();
187 port = sel_netport_find(protocol, pnum);
188 if (likely(port != NULL)) {
189 *sid = port->psec.sid;
190 rcu_read_unlock();
191 return 0;
192 }
193 rcu_read_unlock();
194
195 return sel_netport_sid_slow(protocol, pnum, sid);
196 }
197
198 /**
199 * sel_netport_flush - Flush the entire network port table
200 *
201 * Description:
202 * Remove all entries from the network address table.
203 *
204 */
sel_netport_flush(void)205 void sel_netport_flush(void)
206 {
207 unsigned int idx;
208 struct sel_netport *port, *port_tmp;
209
210 spin_lock_bh(&sel_netport_lock);
211 for (idx = 0; idx < SEL_NETPORT_HASH_SIZE; idx++) {
212 list_for_each_entry_safe(port, port_tmp,
213 &sel_netport_hash[idx].list, list) {
214 list_del_rcu(&port->list);
215 kfree_rcu(port, rcu);
216 }
217 sel_netport_hash[idx].size = 0;
218 }
219 spin_unlock_bh(&sel_netport_lock);
220 }
221
sel_netport_init(void)222 int __init sel_netport_init(void)
223 {
224 int iter;
225
226 if (!selinux_enabled_boot)
227 return 0;
228
229 for (iter = 0; iter < SEL_NETPORT_HASH_SIZE; iter++) {
230 INIT_LIST_HEAD(&sel_netport_hash[iter].list);
231 sel_netport_hash[iter].size = 0;
232 }
233
234 return 0;
235 }
236