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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/slab.h>
15#include <linux/seq_file.h>
16#include <linux/err.h>
17#include <keys/user-type.h>
18#include <linux/uaccess.h>
19#include "internal.h"
20
21static int logon_vet_description(const char *desc);
22
23/*
24 * user defined keys take an arbitrary string as the description and an
25 * arbitrary blob of data as the payload
26 */
27struct key_type key_type_user = {
28 .name = "user",
29 .preparse = user_preparse,
30 .free_preparse = user_free_preparse,
31 .instantiate = generic_key_instantiate,
32 .update = user_update,
33 .revoke = user_revoke,
34 .destroy = user_destroy,
35 .describe = user_describe,
36 .read = user_read,
37};
38
39EXPORT_SYMBOL_GPL(key_type_user);
40
41/*
42 * This key type is essentially the same as key_type_user, but it does
43 * not define a .read op. This is suitable for storing username and
44 * password pairs in the keyring that you do not want to be readable
45 * from userspace.
46 */
47struct key_type key_type_logon = {
48 .name = "logon",
49 .preparse = user_preparse,
50 .free_preparse = user_free_preparse,
51 .instantiate = generic_key_instantiate,
52 .update = user_update,
53 .revoke = user_revoke,
54 .destroy = user_destroy,
55 .describe = user_describe,
56 .vet_description = logon_vet_description,
57};
58EXPORT_SYMBOL_GPL(key_type_logon);
59
60/*
61 * Preparse a user defined key payload
62 */
63int user_preparse(struct key_preparsed_payload *prep)
64{
65 struct user_key_payload *upayload;
66 size_t datalen = prep->datalen;
67
68 if (datalen <= 0 || datalen > 32767 || !prep->data)
69 return -EINVAL;
70
71 upayload = kmalloc(sizeof(*upayload) + datalen, GFP_KERNEL);
72 if (!upayload)
73 return -ENOMEM;
74
75 /* attach the data */
76 prep->quotalen = datalen;
77 prep->payload.data[0] = upayload;
78 upayload->datalen = datalen;
79 memcpy(upayload->data, prep->data, datalen);
80 return 0;
81}
82EXPORT_SYMBOL_GPL(user_preparse);
83
84/*
85 * Free a preparse of a user defined key payload
86 */
87void user_free_preparse(struct key_preparsed_payload *prep)
88{
89 kzfree(prep->payload.data[0]);
90}
91EXPORT_SYMBOL_GPL(user_free_preparse);
92
93static void user_free_payload_rcu(struct rcu_head *head)
94{
95 struct user_key_payload *payload;
96
97 payload = container_of(head, struct user_key_payload, rcu);
98 kzfree(payload);
99}
100
101/*
102 * update a user defined key
103 * - the key's semaphore is write-locked
104 */
105int user_update(struct key *key, struct key_preparsed_payload *prep)
106{
107 struct user_key_payload *zap = NULL;
108 int ret;
109
110 /* check the quota and attach the new data */
111 ret = key_payload_reserve(key, prep->datalen);
112 if (ret < 0)
113 return ret;
114
115 /* attach the new data, displacing the old */
116 key->expiry = prep->expiry;
117 if (!test_bit(KEY_FLAG_NEGATIVE, &key->flags))
118 zap = dereference_key_locked(key);
119 rcu_assign_keypointer(key, prep->payload.data[0]);
120 prep->payload.data[0] = NULL;
121
122 if (zap)
123 call_rcu(&zap->rcu, user_free_payload_rcu);
124 return ret;
125}
126EXPORT_SYMBOL_GPL(user_update);
127
128/*
129 * dispose of the links from a revoked keyring
130 * - called with the key sem write-locked
131 */
132void user_revoke(struct key *key)
133{
134 struct user_key_payload *upayload = user_key_payload_locked(key);
135
136 /* clear the quota */
137 key_payload_reserve(key, 0);
138
139 if (upayload) {
140 rcu_assign_keypointer(key, NULL);
141 call_rcu(&upayload->rcu, user_free_payload_rcu);
142 }
143}
144
145EXPORT_SYMBOL(user_revoke);
146
147/*
148 * dispose of the data dangling from the corpse of a user key
149 */
150void user_destroy(struct key *key)
151{
152 struct user_key_payload *upayload = key->payload.data[0];
153
154 kzfree(upayload);
155}
156
157EXPORT_SYMBOL_GPL(user_destroy);
158
159/*
160 * describe the user key
161 */
162void user_describe(const struct key *key, struct seq_file *m)
163{
164 seq_puts(m, key->description);
165 if (key_is_instantiated(key))
166 seq_printf(m, ": %u", key->datalen);
167}
168
169EXPORT_SYMBOL_GPL(user_describe);
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 const struct user_key_payload *upayload;
178 long ret;
179
180 upayload = user_key_payload_locked(key);
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
195EXPORT_SYMBOL_GPL(user_read);
196
197/* Vet the description for a "logon" key */
198static int logon_vet_description(const char *desc)
199{
200 char *p;
201
202 /* require a "qualified" description string */
203 p = strchr(desc, ':');
204 if (!p)
205 return -EINVAL;
206
207 /* also reject description with ':' as first char */
208 if (p == desc)
209 return -EINVAL;
210
211 return 0;
212}