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
39struct sel_netnode_bkt {
40 unsigned int size;
41 struct list_head list;
42};
43
44struct 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
57static DEFINE_SPINLOCK(sel_netnode_lock);
58static 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 */
69static 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 */
85static 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 */
103static 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(addr: *(const __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 == *(const __be32 *)addr)
125 return node;
126 break;
127 case PF_INET6:
128 if (ipv6_addr_equal(a1: &node->nsec.addr.ipv6,
129 a2: 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 */
145static 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(addr: node->nsec.addr.ipv4);
152 break;
153 case PF_INET6:
154 idx = sel_netnode_hashfn_ipv6(addr: &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(new: &node->list, head: &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(
168 list_tail_rcu(&sel_netnode_hash[idx].list),
169 lockdep_is_held(&sel_netnode_lock)),
170 struct sel_netnode, list);
171 list_del_rcu(entry: &tail->list);
172 kfree_rcu(tail, rcu);
173 } else
174 sel_netnode_hash[idx].size++;
175}
176
177/**
178 * sel_netnode_sid_slow - Lookup the SID of a network address using the policy
179 * @addr: the IP address
180 * @family: the address family
181 * @sid: node SID
182 *
183 * Description:
184 * This function determines the SID of a network address by querying the
185 * security policy. The result is added to the network address table to
186 * speedup future queries. Returns zero on success, negative values on
187 * failure.
188 *
189 */
190static int sel_netnode_sid_slow(const void *addr, u16 family, u32 *sid)
191{
192 int ret;
193 struct sel_netnode *node;
194 struct sel_netnode *new;
195
196 spin_lock_bh(lock: &sel_netnode_lock);
197 node = sel_netnode_find(addr, family);
198 if (node != NULL) {
199 *sid = node->nsec.sid;
200 spin_unlock_bh(lock: &sel_netnode_lock);
201 return 0;
202 }
203
204 /* If this memory allocation fails still return 0. The SID
205 * is valid, it just won't be added to the cache.
206 */
207 new = kmalloc(sizeof(*new), GFP_ATOMIC);
208 switch (family) {
209 case PF_INET:
210 ret = security_node_sid(PF_INET,
211 addr, addrlen: sizeof(struct in_addr), out_sid: sid);
212 if (new)
213 new->nsec.addr.ipv4 = *(const __be32 *)addr;
214 break;
215 case PF_INET6:
216 ret = security_node_sid(PF_INET6,
217 addr, addrlen: sizeof(struct in6_addr), out_sid: sid);
218 if (new)
219 new->nsec.addr.ipv6 = *(const struct in6_addr *)addr;
220 break;
221 default:
222 BUG();
223 ret = -EINVAL;
224 }
225 if (ret == 0 && new) {
226 new->nsec.family = family;
227 new->nsec.sid = *sid;
228 sel_netnode_insert(node: new);
229 } else
230 kfree(objp: new);
231
232 spin_unlock_bh(lock: &sel_netnode_lock);
233 if (unlikely(ret))
234 pr_warn("SELinux: failure in %s(), unable to determine network node label\n",
235 __func__);
236 return ret;
237}
238
239/**
240 * sel_netnode_sid - Lookup the SID of a network address
241 * @addr: the IP address
242 * @family: the address family
243 * @sid: node SID
244 *
245 * Description:
246 * This function determines the SID of a network address using the fastest
247 * method possible. First the address table is queried, but if an entry
248 * can't be found then the policy is queried and the result is added to the
249 * table to speedup future queries. Returns zero on success, negative values
250 * on failure.
251 *
252 */
253int sel_netnode_sid(const void *addr, u16 family, u32 *sid)
254{
255 struct sel_netnode *node;
256
257 rcu_read_lock();
258 node = sel_netnode_find(addr, family);
259 if (likely(node != NULL)) {
260 *sid = node->nsec.sid;
261 rcu_read_unlock();
262 return 0;
263 }
264 rcu_read_unlock();
265
266 return sel_netnode_sid_slow(addr, family, sid);
267}
268
269/**
270 * sel_netnode_flush - Flush the entire network address table
271 *
272 * Description:
273 * Remove all entries from the network address table.
274 *
275 */
276void sel_netnode_flush(void)
277{
278 unsigned int idx;
279 struct sel_netnode *node, *node_tmp;
280
281 spin_lock_bh(lock: &sel_netnode_lock);
282 for (idx = 0; idx < SEL_NETNODE_HASH_SIZE; idx++) {
283 list_for_each_entry_safe(node, node_tmp,
284 &sel_netnode_hash[idx].list, list) {
285 list_del_rcu(entry: &node->list);
286 kfree_rcu(node, rcu);
287 }
288 sel_netnode_hash[idx].size = 0;
289 }
290 spin_unlock_bh(lock: &sel_netnode_lock);
291}
292
293static __init int sel_netnode_init(void)
294{
295 int iter;
296
297 if (!selinux_enabled_boot)
298 return 0;
299
300 for (iter = 0; iter < SEL_NETNODE_HASH_SIZE; iter++) {
301 INIT_LIST_HEAD(list: &sel_netnode_hash[iter].list);
302 sel_netnode_hash[iter].size = 0;
303 }
304
305 return 0;
306}
307
308__initcall(sel_netnode_init);
309