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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 <asm/uaccess.h>
19#include "internal.h"
20
21static int user_instantiate(struct key *key, const void *data, size_t datalen);
22static int user_duplicate(struct key *key, const struct key *source);
23static int user_update(struct key *key, const void *data, size_t datalen);
24static int user_match(const struct key *key, const void *criterion);
25static void user_destroy(struct key *key);
26static void user_describe(const struct key *user, struct seq_file *m);
27static long user_read(const struct key *key,
28 char __user *buffer, size_t buflen);
29
30/*
31 * user defined keys take an arbitrary string as the description and an
32 * arbitrary blob of data as the payload
33 */
34struct key_type key_type_user = {
35 .name = "user",
36 .instantiate = user_instantiate,
37 .duplicate = user_duplicate,
38 .update = user_update,
39 .match = user_match,
40 .destroy = user_destroy,
41 .describe = user_describe,
42 .read = user_read,
43};
44
45/*****************************************************************************/
46/*
47 * instantiate a user defined key
48 */
49static int user_instantiate(struct key *key, const void *data, size_t datalen)
50{
51 int ret;
52
53 ret = -EINVAL;
54 if (datalen <= 0 || datalen > 32767 || !data)
55 goto error;
56
57 ret = key_payload_reserve(key, datalen);
58 if (ret < 0)
59 goto error;
60
61 /* attach the data */
62 ret = -ENOMEM;
63 key->payload.data = kmalloc(datalen, GFP_KERNEL);
64 if (!key->payload.data)
65 goto error;
66
67 memcpy(key->payload.data, data, datalen);
68 ret = 0;
69
70 error:
71 return ret;
72
73} /* end user_instantiate() */
74
75/*****************************************************************************/
76/*
77 * duplicate a user defined key
78 */
79static int user_duplicate(struct key *key, const struct key *source)
80{
81 int ret;
82
83 /* just copy the payload */
84 ret = -ENOMEM;
85 key->payload.data = kmalloc(source->datalen, GFP_KERNEL);
86
87 if (key->payload.data) {
88 key->datalen = source->datalen;
89 memcpy(key->payload.data, source->payload.data, source->datalen);
90 ret = 0;
91 }
92
93 return ret;
94
95} /* end user_duplicate() */
96
97/*****************************************************************************/
98/*
99 * update a user defined key
100 */
101static int user_update(struct key *key, const void *data, size_t datalen)
102{
103 void *new, *zap;
104 int ret;
105
106 ret = -EINVAL;
107 if (datalen <= 0 || datalen > 32767 || !data)
108 goto error;
109
110 /* copy the data */
111 ret = -ENOMEM;
112 new = kmalloc(datalen, GFP_KERNEL);
113 if (!new)
114 goto error;
115
116 memcpy(new, data, datalen);
117
118 /* check the quota and attach the new data */
119 zap = new;
120 write_lock(&key->lock);
121
122 ret = key_payload_reserve(key, datalen);
123
124 if (ret == 0) {
125 /* attach the new data, displacing the old */
126 zap = key->payload.data;
127 key->payload.data = new;
128 key->expiry = 0;
129 }
130
131 write_unlock(&key->lock);
132 kfree(zap);
133
134 error:
135 return ret;
136
137} /* end user_update() */
138
139/*****************************************************************************/
140/*
141 * match users on their name
142 */
143static int user_match(const struct key *key, const void *description)
144{
145 return strcmp(key->description, description) == 0;
146
147} /* end user_match() */
148
149/*****************************************************************************/
150/*
151 * dispose of the data dangling from the corpse of a user
152 */
153static void user_destroy(struct key *key)
154{
155 kfree(key->payload.data);
156
157} /* end user_destroy() */
158
159/*****************************************************************************/
160/*
161 * describe the user
162 */
163static void user_describe(const struct key *key, struct seq_file *m)
164{
165 seq_puts(m, key->description);
166
167 seq_printf(m, ": %u", key->datalen);
168
169} /* end user_describe() */
170
171/*****************************************************************************/
172/*
173 * read the key data
174 */
175static long user_read(const struct key *key,
176 char __user *buffer, size_t buflen)
177{
178 long ret = key->datalen;
179
180 /* we can return the data as is */
181 if (buffer && buflen > 0) {
182 if (buflen > key->datalen)
183 buflen = key->datalen;
184
185 if (copy_to_user(buffer, key->payload.data, buflen) != 0)
186 ret = -EFAULT;
187 }
188
189 return ret;
190
191} /* end user_read() */