summaryrefslogtreecommitdiffstats
path: root/security/selinux/ibpkey.c
blob: e3614ee5f1c0ecb5697221a25ebfe46b885bb35f (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
/*
 * Pkey table
 *
 * SELinux must keep a mapping of Infinband PKEYs to labels/SIDs.  This
 * mapping is maintained as part of the normal policy but a fast cache is
 * needed to reduce the lookup overhead.
 *
 * This code is heavily based on the "netif" and "netport" concept originally
 * developed by
 * James Morris <jmorris@redhat.com> and
 * Paul Moore <paul@paul-moore.com>
 *   (see security/selinux/netif.c and security/selinux/netport.c for more
 *   information)
 *
 */

/*
 * (c) Mellanox Technologies, 2016
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of version 2 of the GNU General Public License as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 */

#include <linux/types.h>
#include <linux/rcupdate.h>
#include <linux/list.h>
#include <linux/spinlock.h>

#include "ibpkey.h"
#include "objsec.h"

#define SEL_PKEY_HASH_SIZE       256
#define SEL_PKEY_HASH_BKT_LIMIT   16

struct sel_ib_pkey_bkt {
	int size;
	struct list_head list;
};

struct sel_ib_pkey {
	struct pkey_security_struct psec;
	struct list_head list;
	struct rcu_head rcu;
};

static LIST_HEAD(sel_ib_pkey_list);
static DEFINE_SPINLOCK(sel_ib_pkey_lock);
static struct sel_ib_pkey_bkt sel_ib_pkey_hash[SEL_PKEY_HASH_SIZE];

/**
 * sel_ib_pkey_hashfn - Hashing function for the pkey table
 * @pkey: pkey number
 *
 * Description:
 * This is the hashing function for the pkey table, it returns the bucket
 * number for the given pkey.
 *
 */
static unsigned int sel_ib_pkey_hashfn(u16 pkey)
{
	return (pkey & (SEL_PKEY_HASH_SIZE - 1));
}

/**
 * sel_ib_pkey_find - Search for a pkey record
 * @subnet_prefix: subnet_prefix
 * @pkey_num: pkey_num
 *
 * Description:
 * Search the pkey table and return the matching record.  If an entry
 * can not be found in the table return NULL.
 *
 */
static struct sel_ib_pkey *sel_ib_pkey_find(u64 subnet_prefix, u16 pkey_num)
{
	unsigned int idx;
	struct sel_ib_pkey *pkey;

	idx = sel_ib_pkey_hashfn(pkey_num);
	list_for_each_entry_rcu(pkey, &sel_ib_pkey_hash[idx].list, list) {
		if (pkey->psec.pkey == pkey_num &&
		    pkey->psec.subnet_prefix == subnet_prefix)
			return pkey;
	}

	return NULL;
}

/**
 * sel_ib_pkey_insert - Insert a new pkey into the table
 * @pkey: the new pkey record
 *
 * Description:
 * Add a new pkey record to the hash table.
 *
 */
static void sel_ib_pkey_insert(struct sel_ib_pkey *pkey)
{
	unsigned int idx;

	/* we need to impose a limit on the growth of the hash table so check
	 * this bucket to make sure it is within the specified bounds
	 */
	idx = sel_ib_pkey_hashfn(pkey->psec.pkey);
	list_add_rcu(&pkey->list, &sel_ib_pkey_hash[idx].list);
	if (sel_ib_pkey_hash[idx].size == SEL_PKEY_HASH_BKT_LIMIT) {
		struct sel_ib_pkey *tail;

		tail = list_entry(
			rcu_dereference_protected(
				sel_ib_pkey_hash[idx].list.prev,
				lockdep_is_held(&sel_ib_pkey_lock)),
			struct sel_ib_pkey, list);
		list_del_rcu(&tail->list);
		kfree_rcu(tail, rcu);
	} else {
		sel_ib_pkey_hash[idx].size++;
	}
}

/**
 * sel_ib_pkey_sid_slow - Lookup the SID of a pkey using the policy
 * @subnet_prefix: subnet prefix
 * @pkey_num: pkey number
 * @sid: pkey SID
 *
 * Description:
 * This function determines the SID of a pkey by querying the security
 * policy.  The result is added to the pkey table to speedup future
 * queries.  Returns zero on success, negative values on failure.
 *
 */
static int sel_ib_pkey_sid_slow(u64 subnet_prefix, u16 pkey_num, u32 *sid)
{
	int ret;
	struct sel_ib_pkey *pkey;
	struct sel_ib_pkey *new = NULL;
	unsigned long flags;

	spin_lock_irqsave(&sel_ib_pkey_lock, flags);
	pkey = sel_ib_pkey_find(subnet_prefix, pkey_num);
	if (pkey) {
		*sid = pkey->psec.sid;
		spin_unlock_irqrestore(&sel_ib_pkey_lock, flags);
		return 0;
	}

	ret = security_ib_pkey_sid(subnet_prefix, pkey_num, sid);
	if (ret)
		goto out;

	/* If this memory allocation fails still return 0. The SID
	 * is valid, it just won't be added to the cache.
	 */
	new = kzalloc(sizeof(*new), GFP_ATOMIC);
	if (!new)
		goto out;

	new->psec.subnet_prefix = subnet_prefix;
	new->psec.pkey = pkey_num;
	new->psec.sid = *sid;
	sel_ib_pkey_insert(new);

out:
	spin_unlock_irqrestore(&sel_ib_pkey_lock, flags);
	return ret;
}

/**
 * sel_ib_pkey_sid - Lookup the SID of a PKEY
 * @subnet_prefix: subnet_prefix
 * @pkey_num: pkey number
 * @sid: pkey SID
 *
 * Description:
 * This function determines the SID of a PKEY using the fastest method
 * possible.  First the pkey table is queried, but if an entry can't be found
 * then the policy is queried and the result is added to the table to speedup
 * future queries.  Returns zero on success, negative values on failure.
 *
 */
int sel_ib_pkey_sid(u64 subnet_prefix, u16 pkey_num, u32 *sid)
{
	struct sel_ib_pkey *pkey;

	rcu_read_lock();
	pkey = sel_ib_pkey_find(subnet_prefix, pkey_num);
	if (pkey) {
		*sid = pkey->psec.sid;
		rcu_read_unlock();
		return 0;
	}
	rcu_read_unlock();

	return sel_ib_pkey_sid_slow(subnet_prefix, pkey_num, sid);
}

/**
 * sel_ib_pkey_flush - Flush the entire pkey table
 *
 * Description:
 * Remove all entries from the pkey table
 *
 */
void sel_ib_pkey_flush(void)
{
	unsigned int idx;
	struct sel_ib_pkey *pkey, *pkey_tmp;
	unsigned long flags;

	spin_lock_irqsave(&sel_ib_pkey_lock, flags);
	for (idx = 0; idx < SEL_PKEY_HASH_SIZE; idx++) {
		list_for_each_entry_safe(pkey, pkey_tmp,
					 &sel_ib_pkey_hash[idx].list, list) {
			list_del_rcu(&pkey->list);
			kfree_rcu(pkey, rcu);
		}
		sel_ib_pkey_hash[idx].size = 0;
	}
	spin_unlock_irqrestore(&sel_ib_pkey_lock, flags);
}

static __init int sel_ib_pkey_init(void)
{
	int iter;

	if (!selinux_enabled)
		return 0;

	for (iter = 0; iter < SEL_PKEY_HASH_SIZE; iter++) {
		INIT_LIST_HEAD(&sel_ib_pkey_hash[iter].list);
		sel_ib_pkey_hash[iter].size = 0;
	}

	return 0;
}

subsys_initcall(sel_ib_pkey_init);