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1/* user_defined.c: user defined key type
2 *
3 * Copyright (C) 2004 Red Hat, Inc. All Rights Reserved.
4 * Written by David Howells (dhowells@redhat.com)
5 *
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public License
8 * as published by the Free Software Foundation; either version
9 * 2 of the License, or (at your option) any later version.
10 */
11
12#include <linux/module.h>
13#include <linux/init.h>
14#include <linux/sched.h>
15#include <linux/slab.h>
16#include <linux/seq_file.h>
17#include <linux/err.h>
18#include <keys/user-type.h>
19#include <asm/uaccess.h>
20#include "internal.h"
21
22/*
23 * user defined keys take an arbitrary string as the description and an
24 * arbitrary blob of data as the payload
25 */
26struct key_type key_type_user = {
27 .name = "user",
28 .instantiate = user_instantiate,
29 .update = user_update,
30 .match = user_match,
31 .destroy = user_destroy,
32 .describe = user_describe,
33 .read = user_read,
34};
35
36EXPORT_SYMBOL_GPL(key_type_user);
37
38/*****************************************************************************/
39/*
40 * instantiate a user defined key
41 */
42int user_instantiate(struct key *key, const void *data, size_t datalen)
43{
44 struct user_key_payload *upayload;
45 int ret;
46
47 ret = -EINVAL;
48 if (datalen <= 0 || datalen > 32767 || !data)
49 goto error;
50
51 ret = key_payload_reserve(key, datalen);
52 if (ret < 0)
53 goto error;
54
55 ret = -ENOMEM;
56 upayload = kmalloc(sizeof(*upayload) + datalen, GFP_KERNEL);
57 if (!upayload)
58 goto error;
59
60 /* attach the data */
61 upayload->datalen = datalen;
62 memcpy(upayload->data, data, datalen);
63 rcu_assign_pointer(key->payload.data, upayload);
64 ret = 0;
65
66error:
67 return ret;
68
69} /* end user_instantiate() */
70EXPORT_SYMBOL_GPL(user_instantiate);
71
72/*****************************************************************************/
73/*
74 * dispose of the old data from an updated user defined key
75 */
76static void user_update_rcu_disposal(struct rcu_head *rcu)
77{
78 struct user_key_payload *upayload;
79
80 upayload = container_of(rcu, struct user_key_payload, rcu);
81
82 kfree(upayload);
83
84} /* end user_update_rcu_disposal() */
85
86/*****************************************************************************/
87/*
88 * update a user defined key
89 * - the key's semaphore is write-locked
90 */
91int user_update(struct key *key, const void *data, size_t datalen)
92{
93 struct user_key_payload *upayload, *zap;
94 int ret;
95
96 ret = -EINVAL;
97 if (datalen <= 0 || datalen > 32767 || !data)
98 goto error;
99
100 /* construct a replacement payload */
101 ret = -ENOMEM;
102 upayload = kmalloc(sizeof(*upayload) + datalen, GFP_KERNEL);
103 if (!upayload)
104 goto error;
105
106 upayload->datalen = datalen;
107 memcpy(upayload->data, data, datalen);
108
109 /* check the quota and attach the new data */
110 zap = upayload;
111
112 ret = key_payload_reserve(key, datalen);
113
114 if (ret == 0) {
115 /* attach the new data, displacing the old */
116 zap = key->payload.data;
117 rcu_assign_pointer(key->payload.data, upayload);
118 key->expiry = 0;
119 }
120
121 call_rcu(&zap->rcu, user_update_rcu_disposal);
122
123error:
124 return ret;
125
126} /* end user_update() */
127
128EXPORT_SYMBOL_GPL(user_update);
129
130/*****************************************************************************/
131/*
132 * match users on their name
133 */
134int user_match(const struct key *key, const void *description)
135{
136 return strcmp(key->description, description) == 0;
137
138} /* end user_match() */
139
140EXPORT_SYMBOL_GPL(user_match);
141
142/*****************************************************************************/
143/*
144 * dispose of the data dangling from the corpse of a user
145 */
146void user_destroy(struct key *key)
147{
148 struct user_key_payload *upayload = key->payload.data;
149
150 kfree(upayload);
151
152} /* end user_destroy() */
153
154EXPORT_SYMBOL_GPL(user_destroy);
155
156/*****************************************************************************/
157/*
158 * describe the user key
159 */
160void user_describe(const struct key *key, struct seq_file *m)
161{
162 seq_puts(m, key->description);
163
164 seq_printf(m, ": %u", key->datalen);
165
166} /* end user_describe() */
167
168EXPORT_SYMBOL_GPL(user_describe);
169
170/*****************************************************************************/
171/*
172 * read the key data
173 * - the key's semaphore is read-locked
174 */
175long user_read(const struct key *key, char __user *buffer, size_t buflen)
176{
177 struct user_key_payload *upayload;
178 long ret;
179
180 upayload = rcu_dereference(key->payload.data);
181 ret = upayload->datalen;
182
183 /* we can return the data as is */
184 if (buffer && buflen > 0) {
185 if (buflen > upayload->datalen)
186 buflen = upayload->datalen;
187
188 if (copy_to_user(buffer, upayload->data, buflen) != 0)
189 ret = -EFAULT;
190 }
191
192 return ret;
193
194} /* end user_read() */
195
196EXPORT_SYMBOL_GPL(user_read);