1 // SPDX-License-Identifier: GPL-2.0-only
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
10 * Author: Paul Moore <paul@paul-moore.com>
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)
18 * (c) Copyright Hewlett-Packard Development Company, L.P., 2007
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>
27 #include <linux/in6.h>
29 #include <linux/ipv6.h>
36 #define SEL_NETNODE_HASH_SIZE 256
37 #define SEL_NETNODE_HASH_BKT_LIMIT 16
39 struct sel_netnode_bkt {
41 struct list_head list;
45 struct netnode_security_struct nsec;
47 struct list_head list;
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
57 static DEFINE_SPINLOCK(sel_netnode_lock);
58 static struct sel_netnode_bkt sel_netnode_hash[SEL_NETNODE_HASH_SIZE];
61 * sel_netnode_hashfn_ipv4 - IPv4 hashing function for the node table
65 * This is the IPv4 hashing function for the node interface table, it returns
66 * the bucket number for the given IP address.
69 static unsigned int sel_netnode_hashfn_ipv4(__be32 addr)
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));
77 * sel_netnode_hashfn_ipv6 - IPv6 hashing function for the node table
81 * This is the IPv6 hashing function for the node interface table, it returns
82 * the bucket number for the given IP address.
85 static unsigned int sel_netnode_hashfn_ipv6(const struct in6_addr *addr)
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
90 return (addr->s6_addr32[3] & (SEL_NETNODE_HASH_SIZE - 1));
94 * sel_netnode_find - Search for a node record
96 * @family: address family
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.
103 static struct sel_netnode *sel_netnode_find(const void *addr, u16 family)
106 struct sel_netnode *node;
110 idx = sel_netnode_hashfn_ipv4(*(__be32 *)addr);
113 idx = sel_netnode_hashfn_ipv6(addr);
120 list_for_each_entry_rcu(node, &sel_netnode_hash[idx].list, list)
121 if (node->nsec.family == family)
124 if (node->nsec.addr.ipv4 == *(__be32 *)addr)
128 if (ipv6_addr_equal(&node->nsec.addr.ipv6,
138 * sel_netnode_insert - Insert a new node into the table
139 * @node: the new node record
142 * Add a new node record to the network address hash table.
145 static void sel_netnode_insert(struct sel_netnode *node)
149 switch (node->nsec.family) {
151 idx = sel_netnode_hashfn_ipv4(node->nsec.addr.ipv4);
154 idx = sel_netnode_hashfn_ipv6(&node->nsec.addr.ipv6);
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;
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);
173 sel_netnode_hash[idx].size++;
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
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
189 static int sel_netnode_sid_slow(void *addr, u16 family, u32 *sid)
192 struct sel_netnode *node;
193 struct sel_netnode *new;
195 spin_lock_bh(&sel_netnode_lock);
196 node = sel_netnode_find(addr, family);
198 *sid = node->nsec.sid;
199 spin_unlock_bh(&sel_netnode_lock);
203 new = kzalloc(sizeof(*new), GFP_ATOMIC);
206 ret = security_node_sid(&selinux_state, PF_INET,
207 addr, sizeof(struct in_addr), sid);
209 new->nsec.addr.ipv4 = *(__be32 *)addr;
212 ret = security_node_sid(&selinux_state, PF_INET6,
213 addr, sizeof(struct in6_addr), sid);
215 new->nsec.addr.ipv6 = *(struct in6_addr *)addr;
221 if (ret == 0 && new) {
222 new->nsec.family = family;
223 new->nsec.sid = *sid;
224 sel_netnode_insert(new);
228 spin_unlock_bh(&sel_netnode_lock);
230 pr_warn("SELinux: failure in %s(), unable to determine network node label\n",
236 * sel_netnode_sid - Lookup the SID of a network address
237 * @addr: the IP address
238 * @family: the address family
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
249 int sel_netnode_sid(void *addr, u16 family, u32 *sid)
251 struct sel_netnode *node;
254 node = sel_netnode_find(addr, family);
256 *sid = node->nsec.sid;
262 return sel_netnode_sid_slow(addr, family, sid);
266 * sel_netnode_flush - Flush the entire network address table
269 * Remove all entries from the network address table.
272 void sel_netnode_flush(void)
275 struct sel_netnode *node, *node_tmp;
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);
284 sel_netnode_hash[idx].size = 0;
286 spin_unlock_bh(&sel_netnode_lock);
289 static __init int sel_netnode_init(void)
293 if (!selinux_enabled_boot)
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;
304 __initcall(sel_netnode_init);