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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 <asm/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[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 kfree(prep->payload[0]);
90}
91EXPORT_SYMBOL_GPL(user_free_preparse);
92
93/*
94 * update a user defined key
95 * - the key's semaphore is write-locked
96 */
97int user_update(struct key *key, struct key_preparsed_payload *prep)
98{
99 struct user_key_payload *upayload, *zap;
100 size_t datalen = prep->datalen;
101 int ret;
102
103 ret = -EINVAL;
104 if (datalen <= 0 || datalen > 32767 || !prep->data)
105 goto error;
106
107 /* construct a replacement payload */
108 ret = -ENOMEM;
109 upayload = kmalloc(sizeof(*upayload) + datalen, GFP_KERNEL);
110 if (!upayload)
111 goto error;
112
113 upayload->datalen = datalen;
114 memcpy(upayload->data, prep->data, datalen);
115
116 /* check the quota and attach the new data */
117 zap = upayload;
118
119 ret = key_payload_reserve(key, datalen);
120
121 if (ret == 0) {
122 /* attach the new data, displacing the old */
123 zap = key->payload.data;
124 rcu_assign_keypointer(key, upayload);
125 key->expiry = 0;
126 }
127
128 if (zap)
129 kfree_rcu(zap, rcu);
130
131error:
132 return ret;
133}
134
135EXPORT_SYMBOL_GPL(user_update);
136
137/*
138 * dispose of the links from a revoked keyring
139 * - called with the key sem write-locked
140 */
141void user_revoke(struct key *key)
142{
143 struct user_key_payload *upayload = key->payload.data;
144
145 /* clear the quota */
146 key_payload_reserve(key, 0);
147
148 if (upayload) {
149 rcu_assign_keypointer(key, NULL);
150 kfree_rcu(upayload, rcu);
151 }
152}
153
154EXPORT_SYMBOL(user_revoke);
155
156/*
157 * dispose of the data dangling from the corpse of a user key
158 */
159void user_destroy(struct key *key)
160{
161 struct user_key_payload *upayload = key->payload.data;
162
163 kfree(upayload);
164}
165
166EXPORT_SYMBOL_GPL(user_destroy);
167
168/*
169 * describe the user key
170 */
171void user_describe(const struct key *key, struct seq_file *m)
172{
173 seq_puts(m, key->description);
174 if (key_is_instantiated(key))
175 seq_printf(m, ": %u", key->datalen);
176}
177
178EXPORT_SYMBOL_GPL(user_describe);
179
180/*
181 * read the key data
182 * - the key's semaphore is read-locked
183 */
184long user_read(const struct key *key, char __user *buffer, size_t buflen)
185{
186 struct user_key_payload *upayload;
187 long ret;
188
189 upayload = rcu_dereference_key(key);
190 ret = upayload->datalen;
191
192 /* we can return the data as is */
193 if (buffer && buflen > 0) {
194 if (buflen > upayload->datalen)
195 buflen = upayload->datalen;
196
197 if (copy_to_user(buffer, upayload->data, buflen) != 0)
198 ret = -EFAULT;
199 }
200
201 return ret;
202}
203
204EXPORT_SYMBOL_GPL(user_read);
205
206/* Vet the description for a "logon" key */
207static int logon_vet_description(const char *desc)
208{
209 char *p;
210
211 /* require a "qualified" description string */
212 p = strchr(desc, ':');
213 if (!p)
214 return -EINVAL;
215
216 /* also reject description with ':' as first char */
217 if (p == desc)
218 return -EINVAL;
219
220 return 0;
221}