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1da177e4 LT |
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 | ||
21 | static int user_instantiate(struct key *key, const void *data, size_t datalen); | |
22 | static int user_duplicate(struct key *key, const struct key *source); | |
23 | static int user_update(struct key *key, const void *data, size_t datalen); | |
24 | static int user_match(const struct key *key, const void *criterion); | |
25 | static void user_destroy(struct key *key); | |
26 | static void user_describe(const struct key *user, struct seq_file *m); | |
27 | static 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 | */ | |
34 | struct 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 | ||
76d8aeab DH |
45 | struct user_key_payload { |
46 | struct rcu_head rcu; /* RCU destructor */ | |
47 | unsigned short datalen; /* length of this data */ | |
48 | char data[0]; /* actual data */ | |
49 | }; | |
50 | ||
16c29b67 MH |
51 | EXPORT_SYMBOL_GPL(key_type_user); |
52 | ||
1da177e4 LT |
53 | /*****************************************************************************/ |
54 | /* | |
55 | * instantiate a user defined key | |
56 | */ | |
57 | static int user_instantiate(struct key *key, const void *data, size_t datalen) | |
58 | { | |
76d8aeab | 59 | struct user_key_payload *upayload; |
1da177e4 LT |
60 | int ret; |
61 | ||
62 | ret = -EINVAL; | |
63 | if (datalen <= 0 || datalen > 32767 || !data) | |
64 | goto error; | |
65 | ||
66 | ret = key_payload_reserve(key, datalen); | |
67 | if (ret < 0) | |
68 | goto error; | |
69 | ||
1da177e4 | 70 | ret = -ENOMEM; |
76d8aeab DH |
71 | upayload = kmalloc(sizeof(*upayload) + datalen, GFP_KERNEL); |
72 | if (!upayload) | |
1da177e4 LT |
73 | goto error; |
74 | ||
76d8aeab DH |
75 | /* attach the data */ |
76 | upayload->datalen = datalen; | |
77 | memcpy(upayload->data, data, datalen); | |
78 | rcu_assign_pointer(key->payload.data, upayload); | |
1da177e4 LT |
79 | ret = 0; |
80 | ||
81 | error: | |
82 | return ret; | |
83 | ||
84 | } /* end user_instantiate() */ | |
85 | ||
86 | /*****************************************************************************/ | |
87 | /* | |
88 | * duplicate a user defined key | |
76d8aeab DH |
89 | * - both keys' semaphores are locked against further modification |
90 | * - the new key cannot yet be accessed | |
1da177e4 LT |
91 | */ |
92 | static int user_duplicate(struct key *key, const struct key *source) | |
93 | { | |
76d8aeab | 94 | struct user_key_payload *upayload, *spayload; |
1da177e4 LT |
95 | int ret; |
96 | ||
97 | /* just copy the payload */ | |
98 | ret = -ENOMEM; | |
76d8aeab DH |
99 | upayload = kmalloc(sizeof(*upayload) + source->datalen, GFP_KERNEL); |
100 | if (upayload) { | |
101 | spayload = rcu_dereference(source->payload.data); | |
102 | BUG_ON(source->datalen != spayload->datalen); | |
1da177e4 | 103 | |
76d8aeab DH |
104 | upayload->datalen = key->datalen = spayload->datalen; |
105 | memcpy(upayload->data, spayload->data, key->datalen); | |
106 | ||
107 | key->payload.data = upayload; | |
1da177e4 LT |
108 | ret = 0; |
109 | } | |
110 | ||
111 | return ret; | |
112 | ||
113 | } /* end user_duplicate() */ | |
114 | ||
76d8aeab DH |
115 | /*****************************************************************************/ |
116 | /* | |
117 | * dispose of the old data from an updated user defined key | |
118 | */ | |
119 | static void user_update_rcu_disposal(struct rcu_head *rcu) | |
120 | { | |
121 | struct user_key_payload *upayload; | |
122 | ||
123 | upayload = container_of(rcu, struct user_key_payload, rcu); | |
124 | ||
125 | kfree(upayload); | |
126 | ||
127 | } /* end user_update_rcu_disposal() */ | |
128 | ||
1da177e4 LT |
129 | /*****************************************************************************/ |
130 | /* | |
131 | * update a user defined key | |
76d8aeab | 132 | * - the key's semaphore is write-locked |
1da177e4 LT |
133 | */ |
134 | static int user_update(struct key *key, const void *data, size_t datalen) | |
135 | { | |
76d8aeab | 136 | struct user_key_payload *upayload, *zap; |
1da177e4 LT |
137 | int ret; |
138 | ||
139 | ret = -EINVAL; | |
140 | if (datalen <= 0 || datalen > 32767 || !data) | |
141 | goto error; | |
142 | ||
76d8aeab | 143 | /* construct a replacement payload */ |
1da177e4 | 144 | ret = -ENOMEM; |
76d8aeab DH |
145 | upayload = kmalloc(sizeof(*upayload) + datalen, GFP_KERNEL); |
146 | if (!upayload) | |
1da177e4 LT |
147 | goto error; |
148 | ||
76d8aeab DH |
149 | upayload->datalen = datalen; |
150 | memcpy(upayload->data, data, datalen); | |
1da177e4 LT |
151 | |
152 | /* check the quota and attach the new data */ | |
76d8aeab | 153 | zap = upayload; |
1da177e4 LT |
154 | |
155 | ret = key_payload_reserve(key, datalen); | |
156 | ||
157 | if (ret == 0) { | |
158 | /* attach the new data, displacing the old */ | |
159 | zap = key->payload.data; | |
76d8aeab | 160 | rcu_assign_pointer(key->payload.data, upayload); |
1da177e4 LT |
161 | key->expiry = 0; |
162 | } | |
163 | ||
76d8aeab | 164 | call_rcu(&zap->rcu, user_update_rcu_disposal); |
1da177e4 LT |
165 | |
166 | error: | |
167 | return ret; | |
168 | ||
169 | } /* end user_update() */ | |
170 | ||
171 | /*****************************************************************************/ | |
172 | /* | |
173 | * match users on their name | |
174 | */ | |
175 | static int user_match(const struct key *key, const void *description) | |
176 | { | |
177 | return strcmp(key->description, description) == 0; | |
178 | ||
179 | } /* end user_match() */ | |
180 | ||
181 | /*****************************************************************************/ | |
182 | /* | |
183 | * dispose of the data dangling from the corpse of a user | |
184 | */ | |
185 | static void user_destroy(struct key *key) | |
186 | { | |
76d8aeab DH |
187 | struct user_key_payload *upayload = key->payload.data; |
188 | ||
189 | kfree(upayload); | |
1da177e4 LT |
190 | |
191 | } /* end user_destroy() */ | |
192 | ||
193 | /*****************************************************************************/ | |
194 | /* | |
76d8aeab | 195 | * describe the user key |
1da177e4 LT |
196 | */ |
197 | static void user_describe(const struct key *key, struct seq_file *m) | |
198 | { | |
199 | seq_puts(m, key->description); | |
200 | ||
201 | seq_printf(m, ": %u", key->datalen); | |
202 | ||
203 | } /* end user_describe() */ | |
204 | ||
205 | /*****************************************************************************/ | |
206 | /* | |
207 | * read the key data | |
76d8aeab | 208 | * - the key's semaphore is read-locked |
1da177e4 LT |
209 | */ |
210 | static long user_read(const struct key *key, | |
211 | char __user *buffer, size_t buflen) | |
212 | { | |
76d8aeab DH |
213 | struct user_key_payload *upayload; |
214 | long ret; | |
215 | ||
216 | upayload = rcu_dereference(key->payload.data); | |
217 | ret = upayload->datalen; | |
1da177e4 LT |
218 | |
219 | /* we can return the data as is */ | |
220 | if (buffer && buflen > 0) { | |
76d8aeab DH |
221 | if (buflen > upayload->datalen) |
222 | buflen = upayload->datalen; | |
1da177e4 | 223 | |
76d8aeab | 224 | if (copy_to_user(buffer, upayload->data, buflen) != 0) |
1da177e4 LT |
225 | ret = -EFAULT; |
226 | } | |
227 | ||
228 | return ret; | |
229 | ||
230 | } /* end user_read() */ |