1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Network node table
4 *
5 * SELinux must keep a mapping of network nodes 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 since most of these queries happen on
8 * a per-packet basis.
9 *
10 * Author: Paul Moore <paul@paul-moore.com>
11 *
12 * This code is heavily based on the "netif" concept originally developed by
13 * James Morris <jmorris@redhat.com>
14 * (see security/selinux/netif.c for more information)
15 */
16
17 /*
18 * (c) Copyright Hewlett-Packard Development Company, L.P., 2007
19 */
20
21 #include <linux/types.h>
22 #include <linux/rcupdate.h>
23 #include <linux/list.h>
24 #include <linux/slab.h>
25 #include <linux/spinlock.h>
26 #include <linux/in.h>
27 #include <linux/in6.h>
28 #include <linux/ip.h>
29 #include <linux/ipv6.h>
30 #include <net/ip.h>
31 #include <net/ipv6.h>
32
33 #include "netnode.h"
34 #include "objsec.h"
35
36 #define SEL_NETNODE_HASH_SIZE 256
37 #define SEL_NETNODE_HASH_BKT_LIMIT 16
38
39 struct sel_netnode_bkt {
40 unsigned int size;
41 struct list_head list;
42 };
43
44 struct sel_netnode {
45 struct netnode_security_struct nsec;
46
47 struct list_head list;
48 struct rcu_head rcu;
49 };
50
51 /* NOTE: we are using a combined hash table for both IPv4 and IPv6, the reason
52 * for this is that I suspect most users will not make heavy use of both
53 * address families at the same time so one table will usually end up wasted,
54 * if this becomes a problem we can always add a hash table for each address
55 * family later */
56
57 static DEFINE_SPINLOCK(sel_netnode_lock);
58 static struct sel_netnode_bkt sel_netnode_hash[SEL_NETNODE_HASH_SIZE];
59
60 /**
61 * sel_netnode_hashfn_ipv4 - IPv4 hashing function for the node table
62 * @addr: IPv4 address
63 *
64 * Description:
65 * This is the IPv4 hashing function for the node interface table, it returns
66 * the bucket number for the given IP address.
67 *
68 */
sel_netnode_hashfn_ipv4(__be32 addr)69 static unsigned int sel_netnode_hashfn_ipv4(__be32 addr)
70 {
71 /* at some point we should determine if the mismatch in byte order
72 * affects the hash function dramatically */
73 return (addr & (SEL_NETNODE_HASH_SIZE - 1));
74 }
75
76 /**
77 * sel_netnode_hashfn_ipv6 - IPv6 hashing function for the node table
78 * @addr: IPv6 address
79 *
80 * Description:
81 * This is the IPv6 hashing function for the node interface table, it returns
82 * the bucket number for the given IP address.
83 *
84 */
sel_netnode_hashfn_ipv6(const struct in6_addr * addr)85 static unsigned int sel_netnode_hashfn_ipv6(const struct in6_addr *addr)
86 {
87 /* just hash the least significant 32 bits to keep things fast (they
88 * are the most likely to be different anyway), we can revisit this
89 * later if needed */
90 return (addr->s6_addr32[3] & (SEL_NETNODE_HASH_SIZE - 1));
91 }
92
93 /**
94 * sel_netnode_find - Search for a node record
95 * @addr: IP address
96 * @family: address family
97 *
98 * Description:
99 * Search the network node table and return the record matching @addr. If an
100 * entry can not be found in the table return NULL.
101 *
102 */
sel_netnode_find(const void * addr,u16 family)103 static struct sel_netnode *sel_netnode_find(const void *addr, u16 family)
104 {
105 unsigned int idx;
106 struct sel_netnode *node;
107
108 switch (family) {
109 case PF_INET:
110 idx = sel_netnode_hashfn_ipv4(*(__be32 *)addr);
111 break;
112 case PF_INET6:
113 idx = sel_netnode_hashfn_ipv6(addr);
114 break;
115 default:
116 BUG();
117 return NULL;
118 }
119
120 list_for_each_entry_rcu(node, &sel_netnode_hash[idx].list, list)
121 if (node->nsec.family == family)
122 switch (family) {
123 case PF_INET:
124 if (node->nsec.addr.ipv4 == *(__be32 *)addr)
125 return node;
126 break;
127 case PF_INET6:
128 if (ipv6_addr_equal(&node->nsec.addr.ipv6,
129 addr))
130 return node;
131 break;
132 }
133
134 return NULL;
135 }
136
137 /**
138 * sel_netnode_insert - Insert a new node into the table
139 * @node: the new node record
140 *
141 * Description:
142 * Add a new node record to the network address hash table.
143 *
144 */
sel_netnode_insert(struct sel_netnode * node)145 static void sel_netnode_insert(struct sel_netnode *node)
146 {
147 unsigned int idx;
148
149 switch (node->nsec.family) {
150 case PF_INET:
151 idx = sel_netnode_hashfn_ipv4(node->nsec.addr.ipv4);
152 break;
153 case PF_INET6:
154 idx = sel_netnode_hashfn_ipv6(&node->nsec.addr.ipv6);
155 break;
156 default:
157 BUG();
158 return;
159 }
160
161 /* we need to impose a limit on the growth of the hash table so check
162 * this bucket to make sure it is within the specified bounds */
163 list_add_rcu(&node->list, &sel_netnode_hash[idx].list);
164 if (sel_netnode_hash[idx].size == SEL_NETNODE_HASH_BKT_LIMIT) {
165 struct sel_netnode *tail;
166 tail = list_entry(
167 rcu_dereference_protected(sel_netnode_hash[idx].list.prev,
168 lockdep_is_held(&sel_netnode_lock)),
169 struct sel_netnode, list);
170 list_del_rcu(&tail->list);
171 kfree_rcu(tail, rcu);
172 } else
173 sel_netnode_hash[idx].size++;
174 }
175
176 /**
177 * sel_netnode_sid_slow - Lookup the SID of a network address using the policy
178 * @addr: the IP address
179 * @family: the address family
180 * @sid: node SID
181 *
182 * Description:
183 * This function determines the SID of a network address by querying the
184 * security policy. The result is added to the network address table to
185 * speedup future queries. Returns zero on success, negative values on
186 * failure.
187 *
188 */
sel_netnode_sid_slow(void * addr,u16 family,u32 * sid)189 static int sel_netnode_sid_slow(void *addr, u16 family, u32 *sid)
190 {
191 int ret;
192 struct sel_netnode *node;
193 struct sel_netnode *new;
194
195 spin_lock_bh(&sel_netnode_lock);
196 node = sel_netnode_find(addr, family);
197 if (node != NULL) {
198 *sid = node->nsec.sid;
199 spin_unlock_bh(&sel_netnode_lock);
200 return 0;
201 }
202
203 new = kzalloc(sizeof(*new), GFP_ATOMIC);
204 switch (family) {
205 case PF_INET:
206 ret = security_node_sid(&selinux_state, PF_INET,
207 addr, sizeof(struct in_addr), sid);
208 if (new)
209 new->nsec.addr.ipv4 = *(__be32 *)addr;
210 break;
211 case PF_INET6:
212 ret = security_node_sid(&selinux_state, PF_INET6,
213 addr, sizeof(struct in6_addr), sid);
214 if (new)
215 new->nsec.addr.ipv6 = *(struct in6_addr *)addr;
216 break;
217 default:
218 BUG();
219 ret = -EINVAL;
220 }
221 if (ret == 0 && new) {
222 new->nsec.family = family;
223 new->nsec.sid = *sid;
224 sel_netnode_insert(new);
225 } else
226 kfree(new);
227
228 spin_unlock_bh(&sel_netnode_lock);
229 if (unlikely(ret))
230 pr_warn("SELinux: failure in %s(), unable to determine network node label\n",
231 __func__);
232 return ret;
233 }
234
235 /**
236 * sel_netnode_sid - Lookup the SID of a network address
237 * @addr: the IP address
238 * @family: the address family
239 * @sid: node SID
240 *
241 * Description:
242 * This function determines the SID of a network address using the fastest
243 * method possible. First the address table is queried, but if an entry
244 * can't be found then the policy is queried and the result is added to the
245 * table to speedup future queries. Returns zero on success, negative values
246 * on failure.
247 *
248 */
sel_netnode_sid(void * addr,u16 family,u32 * sid)249 int sel_netnode_sid(void *addr, u16 family, u32 *sid)
250 {
251 struct sel_netnode *node;
252
253 rcu_read_lock();
254 node = sel_netnode_find(addr, family);
255 if (node != NULL) {
256 *sid = node->nsec.sid;
257 rcu_read_unlock();
258 return 0;
259 }
260 rcu_read_unlock();
261
262 return sel_netnode_sid_slow(addr, family, sid);
263 }
264
265 /**
266 * sel_netnode_flush - Flush the entire network address table
267 *
268 * Description:
269 * Remove all entries from the network address table.
270 *
271 */
sel_netnode_flush(void)272 void sel_netnode_flush(void)
273 {
274 unsigned int idx;
275 struct sel_netnode *node, *node_tmp;
276
277 spin_lock_bh(&sel_netnode_lock);
278 for (idx = 0; idx < SEL_NETNODE_HASH_SIZE; idx++) {
279 list_for_each_entry_safe(node, node_tmp,
280 &sel_netnode_hash[idx].list, list) {
281 list_del_rcu(&node->list);
282 kfree_rcu(node, rcu);
283 }
284 sel_netnode_hash[idx].size = 0;
285 }
286 spin_unlock_bh(&sel_netnode_lock);
287 }
288
sel_netnode_init(void)289 static __init int sel_netnode_init(void)
290 {
291 int iter;
292
293 if (!selinux_enabled_boot)
294 return 0;
295
296 for (iter = 0; iter < SEL_NETNODE_HASH_SIZE; iter++) {
297 INIT_LIST_HEAD(&sel_netnode_hash[iter].list);
298 sel_netnode_hash[iter].size = 0;
299 }
300
301 return 0;
302 }
303
304 __initcall(sel_netnode_init);
305