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 DEFINE_SPINLOCK(sel_ib_pkey_lock);
44 static struct sel_ib_pkey_bkt sel_ib_pkey_hash[SEL_PKEY_HASH_SIZE];
45
46 /**
47 * sel_ib_pkey_hashfn - Hashing function for the pkey table
48 * @pkey: pkey number
49 *
50 * Description:
51 * This is the hashing function for the pkey table, it returns the bucket
52 * number for the given pkey.
53 *
54 */
55 static unsigned int sel_ib_pkey_hashfn(u16 pkey)
56 {
57 return (pkey & (SEL_PKEY_HASH_SIZE - 1));
58 }
59
60 /**
61 * sel_ib_pkey_find - Search for a pkey record
62 * @subnet_prefix: subnet_prefix
63 * @pkey_num: pkey_num
64 *
65 * Description:
66 * Search the pkey table and return the matching record. If an entry
67 * can not be found in the table return NULL.
68 *
69 */
70 static struct sel_ib_pkey *sel_ib_pkey_find(u64 subnet_prefix, u16 pkey_num)
71 {
72 unsigned int idx;
73 struct sel_ib_pkey *pkey;
74
75 idx = sel_ib_pkey_hashfn(pkey_num);
76 list_for_each_entry_rcu(pkey, &sel_ib_pkey_hash[idx].list, list) {
77 if (pkey->psec.pkey == pkey_num &&
78 pkey->psec.subnet_prefix == subnet_prefix)
79 return pkey;
80 }
81
82 return NULL;
83 }
84
85 /**
86 * sel_ib_pkey_insert - Insert a new pkey into the table
87 * @pkey: the new pkey record
88 *
89 * Description:
90 * Add a new pkey record to the hash table.
91 *
92 */
93 static void sel_ib_pkey_insert(struct sel_ib_pkey *pkey)
94 {
95 unsigned int idx;
96
97 /* we need to impose a limit on the growth of the hash table so check
98 * this bucket to make sure it is within the specified bounds
99 */
100 idx = sel_ib_pkey_hashfn(pkey->psec.pkey);
101 list_add_rcu(&pkey->list, &sel_ib_pkey_hash[idx].list);
102 if (sel_ib_pkey_hash[idx].size == SEL_PKEY_HASH_BKT_LIMIT) {
103 struct sel_ib_pkey *tail;
104
105 tail = list_entry(
106 rcu_dereference_protected(
107 list_tail_rcu(&sel_ib_pkey_hash[idx].list),
108 lockdep_is_held(&sel_ib_pkey_lock)),
109 struct sel_ib_pkey, list);
110 list_del_rcu(&tail->list);
111 kfree_rcu(tail, rcu);
112 } else {
113 sel_ib_pkey_hash[idx].size++;
114 }
115 }
116
117 /**
118 * sel_ib_pkey_sid_slow - Lookup the SID of a pkey using the policy
119 * @subnet_prefix: subnet prefix
120 * @pkey_num: pkey number
121 * @sid: pkey SID
122 *
123 * Description:
124 * This function determines the SID of a pkey by querying the security
125 * policy. The result is added to the pkey table to speedup future
126 * queries. Returns zero on success, negative values on failure.
127 *
128 */
129 static int sel_ib_pkey_sid_slow(u64 subnet_prefix, u16 pkey_num, u32 *sid)
130 {
131 int ret;
132 struct sel_ib_pkey *pkey;
133 struct sel_ib_pkey *new = NULL;
134 unsigned long flags;
135
136 spin_lock_irqsave(&sel_ib_pkey_lock, flags);
137 pkey = sel_ib_pkey_find(subnet_prefix, pkey_num);
138 if (pkey) {
139 *sid = pkey->psec.sid;
140 spin_unlock_irqrestore(&sel_ib_pkey_lock, flags);
141 return 0;
142 }
143
144 ret = security_ib_pkey_sid(subnet_prefix, pkey_num,
145 sid);
146 if (ret)
147 goto out;
148
149 /* If this memory allocation fails still return 0. The SID
150 * is valid, it just won't be added to the cache.
151 */
152 new = kzalloc(sizeof(*new), GFP_ATOMIC);
153 if (!new) {
154 ret = -ENOMEM;
155 goto out;
156 }
157
158 new->psec.subnet_prefix = subnet_prefix;
159 new->psec.pkey = pkey_num;
160 new->psec.sid = *sid;
161 sel_ib_pkey_insert(new);
162
163 out:
164 spin_unlock_irqrestore(&sel_ib_pkey_lock, flags);
165 return ret;
166 }
167
168 /**
169 * sel_ib_pkey_sid - Lookup the SID of a PKEY
170 * @subnet_prefix: subnet_prefix
171 * @pkey_num: pkey number
172 * @sid: pkey SID
173 *
174 * Description:
175 * This function determines the SID of a PKEY using the fastest method
176 * possible. First the pkey table is queried, but if an entry can't be found
177 * then the policy is queried and the result is added to the table to speedup
178 * future queries. Returns zero on success, negative values on failure.
179 *
180 */
181 int sel_ib_pkey_sid(u64 subnet_prefix, u16 pkey_num, u32 *sid)
182 {
183 struct sel_ib_pkey *pkey;
184
185 rcu_read_lock();
186 pkey = sel_ib_pkey_find(subnet_prefix, pkey_num);
187 if (pkey) {
188 *sid = pkey->psec.sid;
189 rcu_read_unlock();
190 return 0;
191 }
192 rcu_read_unlock();
193
194 return sel_ib_pkey_sid_slow(subnet_prefix, pkey_num, sid);
195 }
196
197 /**
198 * sel_ib_pkey_flush - Flush the entire pkey table
199 *
200 * Description:
201 * Remove all entries from the pkey table
202 *
203 */
204 void sel_ib_pkey_flush(void)
205 {
206 unsigned int idx;
207 struct sel_ib_pkey *pkey, *pkey_tmp;
208 unsigned long flags;
209
210 spin_lock_irqsave(&sel_ib_pkey_lock, flags);
211 for (idx = 0; idx < SEL_PKEY_HASH_SIZE; idx++) {
212 list_for_each_entry_safe(pkey, pkey_tmp,
213 &sel_ib_pkey_hash[idx].list, list) {
214 list_del_rcu(&pkey->list);
215 kfree_rcu(pkey, rcu);
216 }
217 sel_ib_pkey_hash[idx].size = 0;
218 }
219 spin_unlock_irqrestore(&sel_ib_pkey_lock, flags);
220 }
221
222 static __init int sel_ib_pkey_init(void)
223 {
224 int iter;
225
226 if (!selinux_enabled_boot)
227 return 0;
228
229 for (iter = 0; iter < SEL_PKEY_HASH_SIZE; iter++) {
230 INIT_LIST_HEAD(&sel_ib_pkey_hash[iter].list);
231 sel_ib_pkey_hash[iter].size = 0;
232 }
233
234 return 0;
235 }
236
237 subsys_initcall(sel_ib_pkey_init);
238
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