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 "initcalls.h"
27 #include "ibpkey.h"
28 #include "objsec.h"
29
30 #define SEL_PKEY_HASH_SIZE 256
31 #define SEL_PKEY_HASH_BKT_LIMIT 16
32
33 struct sel_ib_pkey_bkt {
34 int size;
35 struct list_head list;
36 };
37
38 struct sel_ib_pkey {
39 struct pkey_security_struct psec;
40 struct list_head list;
41 struct rcu_head rcu;
42 };
43
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 list_tail_rcu(&sel_ib_pkey_hash[idx].list),
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;
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(subnet_prefix, pkey_num,
146 sid);
147 if (ret)
148 goto out;
149
150 new = kmalloc(sizeof(*new), GFP_ATOMIC);
151 if (!new) {
152 /* If this memory allocation fails still return 0. The SID
153 * is valid, it just won't be added to the cache.
154 */
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 */
sel_ib_pkey_sid(u64 subnet_prefix,u16 pkey_num,u32 * sid)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 (likely(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 */
sel_ib_pkey_flush(void)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
sel_ib_pkey_init(void)222 int __init 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