fs: use kmem_cache_zalloc instead
[pv_ops_mirror.git] / security / keys / user_defined.c
blob7c687d568221cd71a3e863b9c9c50f5cd9352005
1 /* user_defined.c: user defined key type
3 * Copyright (C) 2004 Red Hat, Inc. All Rights Reserved.
4 * Written by David Howells (dhowells@redhat.com)
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.
12 #include <linux/module.h>
13 #include <linux/init.h>
14 #include <linux/slab.h>
15 #include <linux/seq_file.h>
16 #include <linux/err.h>
17 #include <keys/user-type.h>
18 #include <asm/uaccess.h>
19 #include "internal.h"
22 * user defined keys take an arbitrary string as the description and an
23 * arbitrary blob of data as the payload
25 struct key_type key_type_user = {
26 .name = "user",
27 .instantiate = user_instantiate,
28 .update = user_update,
29 .match = user_match,
30 .revoke = user_revoke,
31 .destroy = user_destroy,
32 .describe = user_describe,
33 .read = user_read,
36 EXPORT_SYMBOL_GPL(key_type_user);
38 /*****************************************************************************/
40 * instantiate a user defined key
42 int user_instantiate(struct key *key, const void *data, size_t datalen)
44 struct user_key_payload *upayload;
45 int ret;
47 ret = -EINVAL;
48 if (datalen <= 0 || datalen > 32767 || !data)
49 goto error;
51 ret = key_payload_reserve(key, datalen);
52 if (ret < 0)
53 goto error;
55 ret = -ENOMEM;
56 upayload = kmalloc(sizeof(*upayload) + datalen, GFP_KERNEL);
57 if (!upayload)
58 goto error;
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;
66 error:
67 return ret;
69 } /* end user_instantiate() */
71 EXPORT_SYMBOL_GPL(user_instantiate);
73 /*****************************************************************************/
75 * dispose of the old data from an updated user defined key
77 static void user_update_rcu_disposal(struct rcu_head *rcu)
79 struct user_key_payload *upayload;
81 upayload = container_of(rcu, struct user_key_payload, rcu);
83 kfree(upayload);
85 } /* end user_update_rcu_disposal() */
87 /*****************************************************************************/
89 * update a user defined key
90 * - the key's semaphore is write-locked
92 int user_update(struct key *key, const void *data, size_t datalen)
94 struct user_key_payload *upayload, *zap;
95 int ret;
97 ret = -EINVAL;
98 if (datalen <= 0 || datalen > 32767 || !data)
99 goto error;
101 /* construct a replacement payload */
102 ret = -ENOMEM;
103 upayload = kmalloc(sizeof(*upayload) + datalen, GFP_KERNEL);
104 if (!upayload)
105 goto error;
107 upayload->datalen = datalen;
108 memcpy(upayload->data, data, datalen);
110 /* check the quota and attach the new data */
111 zap = upayload;
113 ret = key_payload_reserve(key, datalen);
115 if (ret == 0) {
116 /* attach the new data, displacing the old */
117 zap = key->payload.data;
118 rcu_assign_pointer(key->payload.data, upayload);
119 key->expiry = 0;
122 call_rcu(&zap->rcu, user_update_rcu_disposal);
124 error:
125 return ret;
127 } /* end user_update() */
129 EXPORT_SYMBOL_GPL(user_update);
131 /*****************************************************************************/
133 * match users on their name
135 int user_match(const struct key *key, const void *description)
137 return strcmp(key->description, description) == 0;
139 } /* end user_match() */
141 EXPORT_SYMBOL_GPL(user_match);
143 /*****************************************************************************/
145 * dispose of the links from a revoked keyring
146 * - called with the key sem write-locked
148 void user_revoke(struct key *key)
150 struct user_key_payload *upayload = key->payload.data;
152 /* clear the quota */
153 key_payload_reserve(key, 0);
155 if (upayload) {
156 rcu_assign_pointer(key->payload.data, NULL);
157 call_rcu(&upayload->rcu, user_update_rcu_disposal);
160 } /* end user_revoke() */
162 EXPORT_SYMBOL(user_revoke);
164 /*****************************************************************************/
166 * dispose of the data dangling from the corpse of a user key
168 void user_destroy(struct key *key)
170 struct user_key_payload *upayload = key->payload.data;
172 kfree(upayload);
174 } /* end user_destroy() */
176 EXPORT_SYMBOL_GPL(user_destroy);
178 /*****************************************************************************/
180 * describe the user key
182 void user_describe(const struct key *key, struct seq_file *m)
184 seq_puts(m, key->description);
186 seq_printf(m, ": %u", key->datalen);
188 } /* end user_describe() */
190 EXPORT_SYMBOL_GPL(user_describe);
192 /*****************************************************************************/
194 * read the key data
195 * - the key's semaphore is read-locked
197 long user_read(const struct key *key, char __user *buffer, size_t buflen)
199 struct user_key_payload *upayload;
200 long ret;
202 upayload = rcu_dereference(key->payload.data);
203 ret = upayload->datalen;
205 /* we can return the data as is */
206 if (buffer && buflen > 0) {
207 if (buflen > upayload->datalen)
208 buflen = upayload->datalen;
210 if (copy_to_user(buffer, upayload->data, buflen) != 0)
211 ret = -EFAULT;
214 return ret;
216 } /* end user_read() */
218 EXPORT_SYMBOL_GPL(user_read);