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
21 static 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 */
27 struct key_type key_type_user = {
28 .name = "user",
29 .instantiate = user_instantiate,
30 .update = user_update,
31 .match = user_match,
32 .revoke = user_revoke,
33 .destroy = user_destroy,
34 .describe = user_describe,
35 .read = user_read,
36 };
37
38 EXPORT_SYMBOL_GPL(key_type_user);
39
40 /*
41 * This key type is essentially the same as key_type_user, but it does
42 * not define a .read op. This is suitable for storing username and
43 * password pairs in the keyring that you do not want to be readable
44 * from userspace.
45 */
46 struct key_type key_type_logon = {
47 .name = "logon",
48 .instantiate = user_instantiate,
49 .update = user_update,
50 .match = user_match,
51 .revoke = user_revoke,
52 .destroy = user_destroy,
53 .describe = user_describe,
54 .vet_description = logon_vet_description,
55 };
56 EXPORT_SYMBOL_GPL(key_type_logon);
57
58 /*
59 * instantiate a user defined key
60 */
user_instantiate(struct key * key,const void * data,size_t datalen)61 int user_instantiate(struct key *key, const void *data, size_t datalen)
62 {
63 struct user_key_payload *upayload;
64 int ret;
65
66 ret = -EINVAL;
67 if (datalen <= 0 || datalen > 32767 || !data)
68 goto error;
69
70 ret = key_payload_reserve(key, datalen);
71 if (ret < 0)
72 goto error;
73
74 ret = -ENOMEM;
75 upayload = kmalloc(sizeof(*upayload) + datalen, GFP_KERNEL);
76 if (!upayload)
77 goto error;
78
79 /* attach the data */
80 upayload->datalen = datalen;
81 memcpy(upayload->data, data, datalen);
82 rcu_assign_keypointer(key, upayload);
83 ret = 0;
84
85 error:
86 return ret;
87 }
88
89 EXPORT_SYMBOL_GPL(user_instantiate);
90
91 /*
92 * update a user defined key
93 * - the key's semaphore is write-locked
94 */
user_update(struct key * key,const void * data,size_t datalen)95 int user_update(struct key *key, const void *data, size_t datalen)
96 {
97 struct user_key_payload *upayload, *zap;
98 int ret;
99
100 ret = -EINVAL;
101 if (datalen <= 0 || datalen > 32767 || !data)
102 goto error;
103
104 /* construct a replacement payload */
105 ret = -ENOMEM;
106 upayload = kmalloc(sizeof(*upayload) + datalen, GFP_KERNEL);
107 if (!upayload)
108 goto error;
109
110 upayload->datalen = datalen;
111 memcpy(upayload->data, data, datalen);
112
113 /* check the quota and attach the new data */
114 zap = upayload;
115
116 ret = key_payload_reserve(key, datalen);
117
118 if (ret == 0) {
119 /* attach the new data, displacing the old */
120 zap = key->payload.data;
121 rcu_assign_keypointer(key, upayload);
122 key->expiry = 0;
123 }
124
125 if (zap)
126 kfree_rcu(zap, rcu);
127
128 error:
129 return ret;
130 }
131
132 EXPORT_SYMBOL_GPL(user_update);
133
134 /*
135 * match users on their name
136 */
user_match(const struct key * key,const void * description)137 int user_match(const struct key *key, const void *description)
138 {
139 return strcmp(key->description, description) == 0;
140 }
141
142 EXPORT_SYMBOL_GPL(user_match);
143
144 /*
145 * dispose of the links from a revoked keyring
146 * - called with the key sem write-locked
147 */
user_revoke(struct key * key)148 void user_revoke(struct key *key)
149 {
150 struct user_key_payload *upayload = key->payload.data;
151
152 /* clear the quota */
153 key_payload_reserve(key, 0);
154
155 if (upayload) {
156 rcu_assign_keypointer(key, NULL);
157 kfree_rcu(upayload, rcu);
158 }
159 }
160
161 EXPORT_SYMBOL(user_revoke);
162
163 /*
164 * dispose of the data dangling from the corpse of a user key
165 */
user_destroy(struct key * key)166 void user_destroy(struct key *key)
167 {
168 struct user_key_payload *upayload = key->payload.data;
169
170 kfree(upayload);
171 }
172
173 EXPORT_SYMBOL_GPL(user_destroy);
174
175 /*
176 * describe the user key
177 */
user_describe(const struct key * key,struct seq_file * m)178 void user_describe(const struct key *key, struct seq_file *m)
179 {
180 seq_puts(m, key->description);
181 if (key_is_instantiated(key))
182 seq_printf(m, ": %u", key->datalen);
183 }
184
185 EXPORT_SYMBOL_GPL(user_describe);
186
187 /*
188 * read the key data
189 * - the key's semaphore is read-locked
190 */
user_read(const struct key * key,char __user * buffer,size_t buflen)191 long user_read(const struct key *key, char __user *buffer, size_t buflen)
192 {
193 struct user_key_payload *upayload;
194 long ret;
195
196 upayload = rcu_dereference_key(key);
197 ret = upayload->datalen;
198
199 /* we can return the data as is */
200 if (buffer && buflen > 0) {
201 if (buflen > upayload->datalen)
202 buflen = upayload->datalen;
203
204 if (copy_to_user(buffer, upayload->data, buflen) != 0)
205 ret = -EFAULT;
206 }
207
208 return ret;
209 }
210
211 EXPORT_SYMBOL_GPL(user_read);
212
213 /* Vet the description for a "logon" key */
logon_vet_description(const char * desc)214 static int logon_vet_description(const char *desc)
215 {
216 char *p;
217
218 /* require a "qualified" description string */
219 p = strchr(desc, ':');
220 if (!p)
221 return -EINVAL;
222
223 /* also reject description with ':' as first char */
224 if (p == desc)
225 return -EINVAL;
226
227 return 0;
228 }
229