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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 | ||
45 | /*****************************************************************************/ | |
46 | /* | |
47 | * instantiate a user defined key | |
48 | */ | |
49 | static int user_instantiate(struct key *key, const void *data, size_t datalen) | |
50 | { | |
51 | int ret; | |
52 | ||
53 | ret = -EINVAL; | |
54 | if (datalen <= 0 || datalen > 32767 || !data) | |
55 | goto error; | |
56 | ||
57 | ret = key_payload_reserve(key, datalen); | |
58 | if (ret < 0) | |
59 | goto error; | |
60 | ||
61 | /* attach the data */ | |
62 | ret = -ENOMEM; | |
63 | key->payload.data = kmalloc(datalen, GFP_KERNEL); | |
64 | if (!key->payload.data) | |
65 | goto error; | |
66 | ||
67 | memcpy(key->payload.data, data, datalen); | |
68 | ret = 0; | |
69 | ||
70 | error: | |
71 | return ret; | |
72 | ||
73 | } /* end user_instantiate() */ | |
74 | ||
75 | /*****************************************************************************/ | |
76 | /* | |
77 | * duplicate a user defined key | |
78 | */ | |
79 | static int user_duplicate(struct key *key, const struct key *source) | |
80 | { | |
81 | int ret; | |
82 | ||
83 | /* just copy the payload */ | |
84 | ret = -ENOMEM; | |
85 | key->payload.data = kmalloc(source->datalen, GFP_KERNEL); | |
86 | ||
87 | if (key->payload.data) { | |
88 | key->datalen = source->datalen; | |
89 | memcpy(key->payload.data, source->payload.data, source->datalen); | |
90 | ret = 0; | |
91 | } | |
92 | ||
93 | return ret; | |
94 | ||
95 | } /* end user_duplicate() */ | |
96 | ||
97 | /*****************************************************************************/ | |
98 | /* | |
99 | * update a user defined key | |
100 | */ | |
101 | static int user_update(struct key *key, const void *data, size_t datalen) | |
102 | { | |
103 | void *new, *zap; | |
104 | int ret; | |
105 | ||
106 | ret = -EINVAL; | |
107 | if (datalen <= 0 || datalen > 32767 || !data) | |
108 | goto error; | |
109 | ||
110 | /* copy the data */ | |
111 | ret = -ENOMEM; | |
112 | new = kmalloc(datalen, GFP_KERNEL); | |
113 | if (!new) | |
114 | goto error; | |
115 | ||
116 | memcpy(new, data, datalen); | |
117 | ||
118 | /* check the quota and attach the new data */ | |
119 | zap = new; | |
120 | write_lock(&key->lock); | |
121 | ||
122 | ret = key_payload_reserve(key, datalen); | |
123 | ||
124 | if (ret == 0) { | |
125 | /* attach the new data, displacing the old */ | |
126 | zap = key->payload.data; | |
127 | key->payload.data = new; | |
128 | key->expiry = 0; | |
129 | } | |
130 | ||
131 | write_unlock(&key->lock); | |
132 | kfree(zap); | |
133 | ||
134 | error: | |
135 | return ret; | |
136 | ||
137 | } /* end user_update() */ | |
138 | ||
139 | /*****************************************************************************/ | |
140 | /* | |
141 | * match users on their name | |
142 | */ | |
143 | static int user_match(const struct key *key, const void *description) | |
144 | { | |
145 | return strcmp(key->description, description) == 0; | |
146 | ||
147 | } /* end user_match() */ | |
148 | ||
149 | /*****************************************************************************/ | |
150 | /* | |
151 | * dispose of the data dangling from the corpse of a user | |
152 | */ | |
153 | static void user_destroy(struct key *key) | |
154 | { | |
155 | kfree(key->payload.data); | |
156 | ||
157 | } /* end user_destroy() */ | |
158 | ||
159 | /*****************************************************************************/ | |
160 | /* | |
161 | * describe the user | |
162 | */ | |
163 | static void user_describe(const struct key *key, struct seq_file *m) | |
164 | { | |
165 | seq_puts(m, key->description); | |
166 | ||
167 | seq_printf(m, ": %u", key->datalen); | |
168 | ||
169 | } /* end user_describe() */ | |
170 | ||
171 | /*****************************************************************************/ | |
172 | /* | |
173 | * read the key data | |
174 | */ | |
175 | static long user_read(const struct key *key, | |
176 | char __user *buffer, size_t buflen) | |
177 | { | |
178 | long ret = key->datalen; | |
179 | ||
180 | /* we can return the data as is */ | |
181 | if (buffer && buflen > 0) { | |
182 | if (buflen > key->datalen) | |
183 | buflen = key->datalen; | |
184 | ||
185 | if (copy_to_user(buffer, key->payload.data, buflen) != 0) | |
186 | ret = -EFAULT; | |
187 | } | |
188 | ||
189 | return ret; | |
190 | ||
191 | } /* end user_read() */ |