1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Pkey table
4 *
5 * SELinux must keep a mapping of Infinband PKEYs 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 * This code is heavily based on the "netif" and "netport" concept originally
10 * developed by
11 * James Morris <jmorris@redhat.com> and
12 * Paul Moore <paul@paul-moore.com>
13 * (see security/selinux/netif.c and security/selinux/netport.c for more
14 * information)
15 */
16
17 /*
18 * (c) Mellanox Technologies, 2016
19 */
20
21 #include <linux/types.h>
22 #include <linux/rcupdate.h>
23 #include <linux/list.h>
24 #include <linux/spinlock.h>
25
26 #include "ibpkey.h"
27 #include "objsec.h"
28
29 #define SEL_PKEY_HASH_SIZE 256
30 #define SEL_PKEY_HASH_BKT_LIMIT 16
31
32 struct sel_ib_pkey_bkt {
33 int size;
34 struct list_head list;
35 };
36
37 struct sel_ib_pkey {
38 struct pkey_security_struct psec;
39 struct list_head list;
40 struct rcu_head rcu;
41 };
42
43 static LIST_HEAD(sel_ib_pkey_list);
44 static DEFINE_SPINLOCK(sel_ib_pkey_lock);
45 static struct sel_ib_pkey_bkt sel_ib_pkey_hash[SEL_PKEY_HASH_SIZE];
46
47 /**
48 * sel_ib_pkey_hashfn - Hashing function for the pkey table
49 * @pkey: pkey number
50 *
51 * Description:
52 * This is the hashing function for the pkey table, it returns the bucket
53 * number for the given pkey.
54 *
55 */
sel_ib_pkey_hashfn(u16 pkey)56 static unsigned int sel_ib_pkey_hashfn(u16 pkey)
57 {
58 return (pkey & (SEL_PKEY_HASH_SIZE - 1));
59 }
60
61 /**
62 * sel_ib_pkey_find - Search for a pkey record
63 * @subnet_prefix: subnet_prefix
64 * @pkey_num: pkey_num
65 *
66 * Description:
67 * Search the pkey table and return the matching record. If an entry
68 * can not be found in the table return NULL.
69 *
70 */
sel_ib_pkey_find(u64 subnet_prefix,u16 pkey_num)71 static struct sel_ib_pkey *sel_ib_pkey_find(u64 subnet_prefix, u16 pkey_num)
72 {
73 unsigned int idx;
74 struct sel_ib_pkey *pkey;
75
76 idx = sel_ib_pkey_hashfn(pkey_num);
77 list_for_each_entry_rcu(pkey, &sel_ib_pkey_hash[idx].list, list) {
78 if (pkey->psec.pkey == pkey_num &&
79 pkey->psec.subnet_prefix == subnet_prefix)
80 return pkey;
81 }
82
83 return NULL;
84 }
85
86 /**
87 * sel_ib_pkey_insert - Insert a new pkey into the table
88 * @pkey: the new pkey record
89 *
90 * Description:
91 * Add a new pkey record to the hash table.
92 *
93 */
sel_ib_pkey_insert(struct sel_ib_pkey * pkey)94 static void sel_ib_pkey_insert(struct sel_ib_pkey *pkey)
95 {
96 unsigned int idx;
97
98 /* we need to impose a limit on the growth of the hash table so check
99 * this bucket to make sure it is within the specified bounds
100 */
101 idx = sel_ib_pkey_hashfn(pkey->psec.pkey);
102 list_add_rcu(&pkey->list, &sel_ib_pkey_hash[idx].list);
103 if (sel_ib_pkey_hash[idx].size == SEL_PKEY_HASH_BKT_LIMIT) {
104 struct sel_ib_pkey *tail;
105
106 tail = list_entry(
107 rcu_dereference_protected(
108 sel_ib_pkey_hash[idx].list.prev,
109 lockdep_is_held(&sel_ib_pkey_lock)),
110 struct sel_ib_pkey, list);
111 list_del_rcu(&tail->list);
112 kfree_rcu(tail, rcu);
113 } else {
114 sel_ib_pkey_hash[idx].size++;
115 }
116 }
117
118 /**
119 * sel_ib_pkey_sid_slow - Lookup the SID of a pkey using the policy
120 * @subnet_prefix: subnet prefix
121 * @pkey_num: pkey number
122 * @sid: pkey SID
123 *
124 * Description:
125 * This function determines the SID of a pkey by querying the security
126 * policy. The result is added to the pkey table to speedup future
127 * queries. Returns zero on success, negative values on failure.
128 *
129 */
sel_ib_pkey_sid_slow(u64 subnet_prefix,u16 pkey_num,u32 * sid)130 static int sel_ib_pkey_sid_slow(u64 subnet_prefix, u16 pkey_num, u32 *sid)
131 {
132 int ret;
133 struct sel_ib_pkey *pkey;
134 struct sel_ib_pkey *new = NULL;
135 unsigned long flags;
136
137 spin_lock_irqsave(&sel_ib_pkey_lock, flags);
138 pkey = sel_ib_pkey_find(subnet_prefix, pkey_num);
139 if (pkey) {
140 *sid = pkey->psec.sid;
141 spin_unlock_irqrestore(&sel_ib_pkey_lock, flags);
142 return 0;
143 }
144
145 ret = security_ib_pkey_sid(&selinux_state, subnet_prefix, pkey_num,
146 sid);
147 if (ret)
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 = kzalloc(sizeof(*new), GFP_ATOMIC);
154 if (!new)
155 goto out;
156
157 new->psec.subnet_prefix = subnet_prefix;
158 new->psec.pkey = pkey_num;
159 new->psec.sid = *sid;
160 sel_ib_pkey_insert(new);
161
162 out:
163 spin_unlock_irqrestore(&sel_ib_pkey_lock, flags);
164 return ret;
165 }
166
167 /**
168 * sel_ib_pkey_sid - Lookup the SID of a PKEY
169 * @subnet_prefix: subnet_prefix
170 * @pkey_num: pkey number
171 * @sid: pkey SID
172 *
173 * Description:
174 * This function determines the SID of a PKEY using the fastest method
175 * possible. First the pkey table is queried, but if an entry can't be found
176 * then the policy is queried and the result is added to the table to speedup
177 * future queries. Returns zero on success, negative values on failure.
178 *
179 */
sel_ib_pkey_sid(u64 subnet_prefix,u16 pkey_num,u32 * sid)180 int sel_ib_pkey_sid(u64 subnet_prefix, u16 pkey_num, u32 *sid)
181 {
182 struct sel_ib_pkey *pkey;
183
184 rcu_read_lock();
185 pkey = sel_ib_pkey_find(subnet_prefix, pkey_num);
186 if (pkey) {
187 *sid = pkey->psec.sid;
188 rcu_read_unlock();
189 return 0;
190 }
191 rcu_read_unlock();
192
193 return sel_ib_pkey_sid_slow(subnet_prefix, pkey_num, sid);
194 }
195
196 /**
197 * sel_ib_pkey_flush - Flush the entire pkey table
198 *
199 * Description:
200 * Remove all entries from the pkey table
201 *
202 */
sel_ib_pkey_flush(void)203 void sel_ib_pkey_flush(void)
204 {
205 unsigned int idx;
206 struct sel_ib_pkey *pkey, *pkey_tmp;
207 unsigned long flags;
208
209 spin_lock_irqsave(&sel_ib_pkey_lock, flags);
210 for (idx = 0; idx < SEL_PKEY_HASH_SIZE; idx++) {
211 list_for_each_entry_safe(pkey, pkey_tmp,
212 &sel_ib_pkey_hash[idx].list, list) {
213 list_del_rcu(&pkey->list);
214 kfree_rcu(pkey, rcu);
215 }
216 sel_ib_pkey_hash[idx].size = 0;
217 }
218 spin_unlock_irqrestore(&sel_ib_pkey_lock, flags);
219 }
220
sel_ib_pkey_init(void)221 static __init int sel_ib_pkey_init(void)
222 {
223 int iter;
224
225 if (!selinux_enabled)
226 return 0;
227
228 for (iter = 0; iter < SEL_PKEY_HASH_SIZE; iter++) {
229 INIT_LIST_HEAD(&sel_ib_pkey_hash[iter].list);
230 sel_ib_pkey_hash[iter].size = 0;
231 }
232
233 return 0;
234 }
235
236 subsys_initcall(sel_ib_pkey_init);
237