summaryrefslogtreecommitdiffstats
path: root/security/keys/user_defined.c
blob: f66baf44f32d16344756635321fffb98b34f0034 (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
/* user_defined.c: user defined key type
 *
 * Copyright (C) 2004 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells (dhowells@redhat.com)
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version
 * 2 of the License, or (at your option) any later version.
 */

#include <linux/module.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/seq_file.h>
#include <linux/err.h>
#include <keys/user-type.h>
#include <asm/uaccess.h>
#include "internal.h"

/*
 * user defined keys take an arbitrary string as the description and an
 * arbitrary blob of data as the payload
 */
struct key_type key_type_user = {
	.name		= "user",
	.instantiate	= user_instantiate,
	.update		= user_update,
	.match		= user_match,
	.revoke		= user_revoke,
	.destroy	= user_destroy,
	.describe	= user_describe,
	.read		= user_read,
};

EXPORT_SYMBOL_GPL(key_type_user);

/*
 * instantiate a user defined key
 */
int user_instantiate(struct key *key, const void *data, size_t datalen)
{
	struct user_key_payload *upayload;
	int ret;

	ret = -EINVAL;
	if (datalen <= 0 || datalen > 32767 || !data)
		goto error;

	ret = key_payload_reserve(key, datalen);
	if (ret < 0)
		goto error;

	ret = -ENOMEM;
	upayload = kmalloc(sizeof(*upayload) + datalen, GFP_KERNEL);
	if (!upayload)
		goto error;

	/* attach the data */
	upayload->datalen = datalen;
	memcpy(upayload->data, data, datalen);
	rcu_assign_pointer(key->payload.data, upayload);
	ret = 0;

error:
	return ret;
}

EXPORT_SYMBOL_GPL(user_instantiate);

/*
 * update a user defined key
 * - the key's semaphore is write-locked
 */
int user_update(struct key *key, const void *data, size_t datalen)
{
	struct user_key_payload *upayload, *zap;
	int ret;

	ret = -EINVAL;
	if (datalen <= 0 || datalen > 32767 || !data)
		goto error;

	/* construct a replacement payload */
	ret = -ENOMEM;
	upayload = kmalloc(sizeof(*upayload) + datalen, GFP_KERNEL);
	if (!upayload)
		goto error;

	upayload->datalen = datalen;
	memcpy(upayload->data, data, datalen);

	/* check the quota and attach the new data */
	zap = upayload;

	ret = key_payload_reserve(key, datalen);

	if (ret == 0) {
		/* attach the new data, displacing the old */
		zap = key->payload.data;
		rcu_assign_pointer(key->payload.data, upayload);
		key->expiry = 0;
	}

	kfree_rcu(zap, rcu);

error:
	return ret;
}

EXPORT_SYMBOL_GPL(user_update);

/*
 * match users on their name
 */
int user_match(const struct key *key, const void *description)
{
	return strcmp(key->description, description) == 0;
}

EXPORT_SYMBOL_GPL(user_match);

/*
 * dispose of the links from a revoked keyring
 * - called with the key sem write-locked
 */
void user_revoke(struct key *key)
{
	struct user_key_payload *upayload = key->payload.data;

	/* clear the quota */
	key_payload_reserve(key, 0);

	if (upayload) {
		rcu_assign_pointer(key->payload.data, NULL);
		kfree_rcu(upayload, rcu);
	}
}

EXPORT_SYMBOL(user_revoke);

/*
 * dispose of the data dangling from the corpse of a user key
 */
void user_destroy(struct key *key)
{
	struct user_key_payload *upayload = key->payload.data;

	kfree(upayload);
}

EXPORT_SYMBOL_GPL(user_destroy);

/*
 * describe the user key
 */
void user_describe(const struct key *key, struct seq_file *m)
{
	seq_puts(m, key->description);

	seq_printf(m, ": %u", key->datalen);
}

EXPORT_SYMBOL_GPL(user_describe);

/*
 * read the key data
 * - the key's semaphore is read-locked
 */
long user_read(const struct key *key, char __user *buffer, size_t buflen)
{
	struct user_key_payload *upayload;
	long ret;

	upayload = rcu_dereference_key(key);
	ret = upayload->datalen;

	/* we can return the data as is */
	if (buffer && buflen > 0) {
		if (buflen > upayload->datalen)
			buflen = upayload->datalen;

		if (copy_to_user(buffer, upayload->data, buflen) != 0)
			ret = -EFAULT;
	}

	return ret;
}

EXPORT_SYMBOL_GPL(user_read);