projects/linux·blob master · refs

307 lines · 7.6 KiB

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 <[email protected]>
11 *
12 * This code is heavily based on the "netif" concept originally developed by
13 * James Morris <[email protected]>
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 "initcalls.h"
34#include "netnode.h"
35#include "objsec.h"
36
37#define SEL_NETNODE_HASH_SIZE 256
38#define SEL_NETNODE_HASH_BKT_LIMIT 16
39
40struct sel_netnode_bkt {
41 unsigned int size;
42 struct list_head list;
43};
44
45struct sel_netnode {
46 struct netnode_security_struct nsec;
47
48 struct list_head list;
49 struct rcu_head rcu;
50};
51
52/* NOTE: we are using a combined hash table for both IPv4 and IPv6, the reason
53 * for this is that I suspect most users will not make heavy use of both
54 * address families at the same time so one table will usually end up wasted,
55 * if this becomes a problem we can always add a hash table for each address
56 * family later */
57
58static DEFINE_SPINLOCK(sel_netnode_lock);
59static struct sel_netnode_bkt sel_netnode_hash[SEL_NETNODE_HASH_SIZE];
60
61/**
62 * sel_netnode_hashfn_ipv4 - IPv4 hashing function for the node table
63 * @addr: IPv4 address
64 *
65 * Description:
66 * This is the IPv4 hashing function for the node interface table, it returns
67 * the bucket number for the given IP address.
68 *
69 */
70static unsigned int sel_netnode_hashfn_ipv4(__be32 addr)
71{
72 /* at some point we should determine if the mismatch in byte order
73 * affects the hash function dramatically */
74 return (addr & (SEL_NETNODE_HASH_SIZE - 1));
75}
76
77/**
78 * sel_netnode_hashfn_ipv6 - IPv6 hashing function for the node table
79 * @addr: IPv6 address
80 *
81 * Description:
82 * This is the IPv6 hashing function for the node interface table, it returns
83 * the bucket number for the given IP address.
84 *
85 */
86static unsigned int sel_netnode_hashfn_ipv6(const struct in6_addr *addr)
87{
88 /* just hash the least significant 32 bits to keep things fast (they
89 * are the most likely to be different anyway), we can revisit this
90 * later if needed */
91 return (addr->s6_addr32[3] & (SEL_NETNODE_HASH_SIZE - 1));
92}
93
94/**
95 * sel_netnode_find - Search for a node record
96 * @addr: IP address
97 * @family: address family
98 *
99 * Description:
100 * Search the network node table and return the record matching @addr. If an
101 * entry can not be found in the table return NULL.
102 *
103 */
104static struct sel_netnode *sel_netnode_find(const void *addr, u16 family)
105{
106 unsigned int idx;
107 struct sel_netnode *node;
108
109 switch (family) {
110 case PF_INET:
111 idx = sel_netnode_hashfn_ipv4(*(const __be32 *)addr);
112 break;
113 case PF_INET6:
114 idx = sel_netnode_hashfn_ipv6(addr);
115 break;
116 default:
117 BUG();
118 return NULL;
119 }
120
121 list_for_each_entry_rcu(node, &sel_netnode_hash[idx].list, list)
122 if (node->nsec.family == family)
123 switch (family) {
124 case PF_INET:
125 if (node->nsec.addr.ipv4 == *(const __be32 *)addr)
126 return node;
127 break;
128 case PF_INET6:
129 if (ipv6_addr_equal(&node->nsec.addr.ipv6,
130 addr))
131 return node;
132 break;
133 }
134
135 return NULL;
136}
137
138/**
139 * sel_netnode_insert - Insert a new node into the table
140 * @node: the new node record
141 *
142 * Description:
143 * Add a new node record to the network address hash table.
144 *
145 */
146static void sel_netnode_insert(struct sel_netnode *node)
147{
148 unsigned int idx;
149
150 switch (node->nsec.family) {
151 case PF_INET:
152 idx = sel_netnode_hashfn_ipv4(node->nsec.addr.ipv4);
153 break;
154 case PF_INET6:
155 idx = sel_netnode_hashfn_ipv6(&node->nsec.addr.ipv6);
156 break;
157 default:
158 BUG();
159 return;
160 }
161
162 /* we need to impose a limit on the growth of the hash table so check
163 * this bucket to make sure it is within the specified bounds */
164 list_add_rcu(&node->list, &sel_netnode_hash[idx].list);
165 if (sel_netnode_hash[idx].size == SEL_NETNODE_HASH_BKT_LIMIT) {
166 struct sel_netnode *tail;
167 tail = list_entry(
168 rcu_dereference_protected(
169 list_tail_rcu(&sel_netnode_hash[idx].list),
170 lockdep_is_held(&sel_netnode_lock)),
171 struct sel_netnode, list);
172 list_del_rcu(&tail->list);
173 kfree_rcu(tail, rcu);
174 } else
175 sel_netnode_hash[idx].size++;
176}
177
178/**
179 * sel_netnode_sid_slow - Lookup the SID of a network address using the policy
180 * @addr: the IP address
181 * @family: the address family
182 * @sid: node SID
183 *
184 * Description:
185 * This function determines the SID of a network address by querying the
186 * security policy. The result is added to the network address table to
187 * speedup future queries. Returns zero on success, negative values on
188 * failure.
189 *
190 */
191static int sel_netnode_sid_slow(const void *addr, u16 family, u32 *sid)
192{
193 int ret;
194 struct sel_netnode *node;
195 struct sel_netnode *new;
196
197 spin_lock_bh(&sel_netnode_lock);
198 node = sel_netnode_find(addr, family);
199 if (node != NULL) {
200 *sid = node->nsec.sid;
201 spin_unlock_bh(&sel_netnode_lock);
202 return 0;
203 }
204
205 /* If this memory allocation fails still return 0. The SID
206 * is valid, it just won't be added to the cache.
207 */
208 new = kmalloc_obj(*new, GFP_ATOMIC);
209 switch (family) {
210 case PF_INET:
211 ret = security_node_sid(PF_INET,
212 addr, sizeof(struct in_addr), sid);
213 if (new)
214 new->nsec.addr.ipv4 = *(const __be32 *)addr;
215 break;
216 case PF_INET6:
217 ret = security_node_sid(PF_INET6,
218 addr, sizeof(struct in6_addr), sid);
219 if (new)
220 new->nsec.addr.ipv6 = *(const struct in6_addr *)addr;
221 break;
222 default:
223 BUG();
224 ret = -EINVAL;
225 }
226 if (ret == 0 && new) {
227 new->nsec.family = family;
228 new->nsec.sid = *sid;
229 sel_netnode_insert(new);
230 } else
231 kfree(new);
232
233 spin_unlock_bh(&sel_netnode_lock);
234 if (unlikely(ret))
235 pr_warn("SELinux: failure in %s(), unable to determine network node label\n",
236 __func__);
237 return ret;
238}
239
240/**
241 * sel_netnode_sid - Lookup the SID of a network address
242 * @addr: the IP address
243 * @family: the address family
244 * @sid: node SID
245 *
246 * Description:
247 * This function determines the SID of a network address using the fastest
248 * method possible. First the address table is queried, but if an entry
249 * can't be found then the policy is queried and the result is added to the
250 * table to speedup future queries. Returns zero on success, negative values
251 * on failure.
252 *
253 */
254int sel_netnode_sid(const void *addr, u16 family, u32 *sid)
255{
256 struct sel_netnode *node;
257
258 rcu_read_lock();
259 node = sel_netnode_find(addr, family);
260 if (likely(node != NULL)) {
261 *sid = node->nsec.sid;
262 rcu_read_unlock();
263 return 0;
264 }
265 rcu_read_unlock();
266
267 return sel_netnode_sid_slow(addr, family, sid);
268}
269
270/**
271 * sel_netnode_flush - Flush the entire network address table
272 *
273 * Description:
274 * Remove all entries from the network address table.
275 *
276 */
277void sel_netnode_flush(void)
278{
279 unsigned int idx;
280 struct sel_netnode *node, *node_tmp;
281
282 spin_lock_bh(&sel_netnode_lock);
283 for (idx = 0; idx < SEL_NETNODE_HASH_SIZE; idx++) {
284 list_for_each_entry_safe(node, node_tmp,
285 &sel_netnode_hash[idx].list, list) {
286 list_del_rcu(&node->list);
287 kfree_rcu(node, rcu);
288 }
289 sel_netnode_hash[idx].size = 0;
290 }
291 spin_unlock_bh(&sel_netnode_lock);
292}
293
294int __init sel_netnode_init(void)
295{
296 int iter;
297
298 if (!selinux_enabled_boot)
299 return 0;
300
301 for (iter = 0; iter < SEL_NETNODE_HASH_SIZE; iter++) {
302 INIT_LIST_HEAD(&sel_netnode_hash[iter].list);
303 sel_netnode_hash[iter].size = 0;
304 }
305
306 return 0;
307}