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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 | ||
21 | /* | |
22 | * user defined keys take an arbitrary string as the description and an | |
23 | * arbitrary blob of data as the payload | |
24 | */ | |
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, | |
34 | }; | |
35 | ||
36 | EXPORT_SYMBOL_GPL(key_type_user); | |
37 | ||
38 | /*****************************************************************************/ | |
39 | /* | |
40 | * instantiate a user defined key | |
41 | */ | |
42 | int user_instantiate(struct key *key, const void *data, size_t datalen) | |
43 | { | |
44 | struct user_key_payload *upayload; | |
45 | int ret; | |
46 | ||
47 | ret = -EINVAL; | |
48 | if (datalen <= 0 || datalen > 32767 || !data) | |
49 | goto error; | |
50 | ||
51 | ret = key_payload_reserve(key, datalen); | |
52 | if (ret < 0) | |
53 | goto error; | |
54 | ||
55 | ret = -ENOMEM; | |
56 | upayload = kmalloc(sizeof(*upayload) + datalen, GFP_KERNEL); | |
57 | if (!upayload) | |
58 | goto error; | |
59 | ||
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; | |
65 | ||
66 | error: | |
67 | return ret; | |
68 | ||
69 | } /* end user_instantiate() */ | |
70 | ||
71 | EXPORT_SYMBOL_GPL(user_instantiate); | |
72 | ||
73 | /*****************************************************************************/ | |
74 | /* | |
75 | * dispose of the old data from an updated user defined key | |
76 | */ | |
77 | static void user_update_rcu_disposal(struct rcu_head *rcu) | |
78 | { | |
79 | struct user_key_payload *upayload; | |
80 | ||
81 | upayload = container_of(rcu, struct user_key_payload, rcu); | |
82 | ||
83 | kfree(upayload); | |
84 | ||
85 | } /* end user_update_rcu_disposal() */ | |
86 | ||
87 | /*****************************************************************************/ | |
88 | /* | |
89 | * update a user defined key | |
90 | * - the key's semaphore is write-locked | |
91 | */ | |
92 | int user_update(struct key *key, const void *data, size_t datalen) | |
93 | { | |
94 | struct user_key_payload *upayload, *zap; | |
95 | int ret; | |
96 | ||
97 | ret = -EINVAL; | |
98 | if (datalen <= 0 || datalen > 32767 || !data) | |
99 | goto error; | |
100 | ||
101 | /* construct a replacement payload */ | |
102 | ret = -ENOMEM; | |
103 | upayload = kmalloc(sizeof(*upayload) + datalen, GFP_KERNEL); | |
104 | if (!upayload) | |
105 | goto error; | |
106 | ||
107 | upayload->datalen = datalen; | |
108 | memcpy(upayload->data, data, datalen); | |
109 | ||
110 | /* check the quota and attach the new data */ | |
111 | zap = upayload; | |
112 | ||
113 | ret = key_payload_reserve(key, datalen); | |
114 | ||
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; | |
120 | } | |
121 | ||
122 | call_rcu(&zap->rcu, user_update_rcu_disposal); | |
123 | ||
124 | error: | |
125 | return ret; | |
126 | ||
127 | } /* end user_update() */ | |
128 | ||
129 | EXPORT_SYMBOL_GPL(user_update); | |
130 | ||
131 | /*****************************************************************************/ | |
132 | /* | |
133 | * match users on their name | |
134 | */ | |
135 | int user_match(const struct key *key, const void *description) | |
136 | { | |
137 | return strcmp(key->description, description) == 0; | |
138 | ||
139 | } /* end user_match() */ | |
140 | ||
141 | EXPORT_SYMBOL_GPL(user_match); | |
142 | ||
143 | /*****************************************************************************/ | |
144 | /* | |
145 | * dispose of the links from a revoked keyring | |
146 | * - called with the key sem write-locked | |
147 | */ | |
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_pointer(key->payload.data, NULL); | |
157 | call_rcu(&upayload->rcu, user_update_rcu_disposal); | |
158 | } | |
159 | ||
160 | } /* end user_revoke() */ | |
161 | ||
162 | EXPORT_SYMBOL(user_revoke); | |
163 | ||
164 | /*****************************************************************************/ | |
165 | /* | |
166 | * dispose of the data dangling from the corpse of a user key | |
167 | */ | |
168 | void user_destroy(struct key *key) | |
169 | { | |
170 | struct user_key_payload *upayload = key->payload.data; | |
171 | ||
172 | kfree(upayload); | |
173 | ||
174 | } /* end user_destroy() */ | |
175 | ||
176 | EXPORT_SYMBOL_GPL(user_destroy); | |
177 | ||
178 | /*****************************************************************************/ | |
179 | /* | |
180 | * describe the user key | |
181 | */ | |
182 | void user_describe(const struct key *key, struct seq_file *m) | |
183 | { | |
184 | seq_puts(m, key->description); | |
185 | ||
186 | seq_printf(m, ": %u", key->datalen); | |
187 | ||
188 | } /* end user_describe() */ | |
189 | ||
190 | EXPORT_SYMBOL_GPL(user_describe); | |
191 | ||
192 | /*****************************************************************************/ | |
193 | /* | |
194 | * read the key data | |
195 | * - the key's semaphore is read-locked | |
196 | */ | |
197 | long user_read(const struct key *key, char __user *buffer, size_t buflen) | |
198 | { | |
199 | struct user_key_payload *upayload; | |
200 | long ret; | |
201 | ||
202 | upayload = rcu_dereference_protected( | |
203 | key->payload.data, rwsem_is_locked(&((struct key *)key)->sem)); | |
204 | ret = upayload->datalen; | |
205 | ||
206 | /* we can return the data as is */ | |
207 | if (buffer && buflen > 0) { | |
208 | if (buflen > upayload->datalen) | |
209 | buflen = upayload->datalen; | |
210 | ||
211 | if (copy_to_user(buffer, upayload->data, buflen) != 0) | |
212 | ret = -EFAULT; | |
213 | } | |
214 | ||
215 | return ret; | |
216 | ||
217 | } /* end user_read() */ | |
218 | ||
219 | EXPORT_SYMBOL_GPL(user_read); |