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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 | 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 | */ |
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 | */ |
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 | */ |
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 | */ |
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 | */ |
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 | */ |
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 | */ |
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 */ |
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 |
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