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3e30148c DH |
1 | /* request_key_auth.c: request key authorisation controlling key def |
2 | * | |
3 | * Copyright (C) 2005 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. | |
f1a9badc DH |
10 | * |
11 | * See Documentation/keys-request-key.txt | |
3e30148c DH |
12 | */ |
13 | ||
14 | #include <linux/module.h> | |
15 | #include <linux/sched.h> | |
16 | #include <linux/err.h> | |
17 | #include <linux/seq_file.h> | |
b5f545c8 | 18 | #include <asm/uaccess.h> |
3e30148c DH |
19 | #include "internal.h" |
20 | ||
21 | static int request_key_auth_instantiate(struct key *, const void *, size_t); | |
22 | static void request_key_auth_describe(const struct key *, struct seq_file *); | |
04c567d9 | 23 | static void request_key_auth_revoke(struct key *); |
3e30148c | 24 | static void request_key_auth_destroy(struct key *); |
b5f545c8 | 25 | static long request_key_auth_read(const struct key *, char __user *, size_t); |
3e30148c DH |
26 | |
27 | /* | |
28 | * the request-key authorisation key type definition | |
29 | */ | |
30 | struct key_type key_type_request_key_auth = { | |
31 | .name = ".request_key_auth", | |
32 | .def_datalen = sizeof(struct request_key_auth), | |
33 | .instantiate = request_key_auth_instantiate, | |
34 | .describe = request_key_auth_describe, | |
04c567d9 | 35 | .revoke = request_key_auth_revoke, |
3e30148c | 36 | .destroy = request_key_auth_destroy, |
b5f545c8 | 37 | .read = request_key_auth_read, |
3e30148c DH |
38 | }; |
39 | ||
40 | /*****************************************************************************/ | |
41 | /* | |
b5f545c8 | 42 | * instantiate a request-key authorisation key |
3e30148c DH |
43 | */ |
44 | static int request_key_auth_instantiate(struct key *key, | |
45 | const void *data, | |
46 | size_t datalen) | |
47 | { | |
b5f545c8 DH |
48 | key->payload.data = (struct request_key_auth *) data; |
49 | return 0; | |
3e30148c DH |
50 | |
51 | } /* end request_key_auth_instantiate() */ | |
52 | ||
53 | /*****************************************************************************/ | |
54 | /* | |
b5f545c8 | 55 | * reading a request-key authorisation key retrieves the callout information |
3e30148c DH |
56 | */ |
57 | static void request_key_auth_describe(const struct key *key, | |
58 | struct seq_file *m) | |
59 | { | |
60 | struct request_key_auth *rka = key->payload.data; | |
61 | ||
62 | seq_puts(m, "key:"); | |
63 | seq_puts(m, key->description); | |
b5f545c8 | 64 | seq_printf(m, " pid:%d ci:%zu", rka->pid, strlen(rka->callout_info)); |
3e30148c DH |
65 | |
66 | } /* end request_key_auth_describe() */ | |
67 | ||
b5f545c8 DH |
68 | /*****************************************************************************/ |
69 | /* | |
70 | * read the callout_info data | |
71 | * - the key's semaphore is read-locked | |
72 | */ | |
73 | static long request_key_auth_read(const struct key *key, | |
74 | char __user *buffer, size_t buflen) | |
75 | { | |
76 | struct request_key_auth *rka = key->payload.data; | |
77 | size_t datalen; | |
78 | long ret; | |
79 | ||
80 | datalen = strlen(rka->callout_info); | |
81 | ret = datalen; | |
82 | ||
83 | /* we can return the data as is */ | |
84 | if (buffer && buflen > 0) { | |
85 | if (buflen > datalen) | |
86 | buflen = datalen; | |
87 | ||
88 | if (copy_to_user(buffer, rka->callout_info, buflen) != 0) | |
89 | ret = -EFAULT; | |
90 | } | |
91 | ||
92 | return ret; | |
93 | ||
94 | } /* end request_key_auth_read() */ | |
95 | ||
04c567d9 DH |
96 | /*****************************************************************************/ |
97 | /* | |
98 | * handle revocation of an authorisation token key | |
99 | * - called with the key sem write-locked | |
100 | */ | |
101 | static void request_key_auth_revoke(struct key *key) | |
102 | { | |
103 | struct request_key_auth *rka = key->payload.data; | |
104 | ||
105 | kenter("{%d}", key->serial); | |
106 | ||
107 | if (rka->context) { | |
108 | put_task_struct(rka->context); | |
109 | rka->context = NULL; | |
110 | } | |
111 | ||
112 | } /* end request_key_auth_revoke() */ | |
113 | ||
3e30148c DH |
114 | /*****************************************************************************/ |
115 | /* | |
116 | * destroy an instantiation authorisation token key | |
117 | */ | |
118 | static void request_key_auth_destroy(struct key *key) | |
119 | { | |
120 | struct request_key_auth *rka = key->payload.data; | |
121 | ||
122 | kenter("{%d}", key->serial); | |
123 | ||
04c567d9 DH |
124 | if (rka->context) { |
125 | put_task_struct(rka->context); | |
126 | rka->context = NULL; | |
127 | } | |
128 | ||
3e30148c | 129 | key_put(rka->target_key); |
74fd92c5 | 130 | kfree(rka); |
3e30148c DH |
131 | |
132 | } /* end request_key_auth_destroy() */ | |
133 | ||
134 | /*****************************************************************************/ | |
135 | /* | |
b5f545c8 DH |
136 | * create an authorisation token for /sbin/request-key or whoever to gain |
137 | * access to the caller's security data | |
3e30148c | 138 | */ |
b5f545c8 | 139 | struct key *request_key_auth_new(struct key *target, const char *callout_info) |
3e30148c | 140 | { |
b5f545c8 DH |
141 | struct request_key_auth *rka, *irka; |
142 | struct key *authkey = NULL; | |
3e30148c DH |
143 | char desc[20]; |
144 | int ret; | |
145 | ||
146 | kenter("%d,", target->serial); | |
147 | ||
b5f545c8 DH |
148 | /* allocate a auth record */ |
149 | rka = kmalloc(sizeof(*rka), GFP_KERNEL); | |
150 | if (!rka) { | |
151 | kleave(" = -ENOMEM"); | |
152 | return ERR_PTR(-ENOMEM); | |
153 | } | |
3e30148c | 154 | |
b5f545c8 DH |
155 | /* see if the calling process is already servicing the key request of |
156 | * another process */ | |
157 | if (current->request_key_auth) { | |
158 | /* it is - use that instantiation context here too */ | |
04c567d9 DH |
159 | down_read(¤t->request_key_auth->sem); |
160 | ||
161 | /* if the auth key has been revoked, then the key we're | |
162 | * servicing is already instantiated */ | |
163 | if (test_bit(KEY_FLAG_REVOKED, | |
164 | ¤t->request_key_auth->flags)) | |
165 | goto auth_key_revoked; | |
166 | ||
b5f545c8 DH |
167 | irka = current->request_key_auth->payload.data; |
168 | rka->context = irka->context; | |
169 | rka->pid = irka->pid; | |
04c567d9 DH |
170 | get_task_struct(rka->context); |
171 | ||
172 | up_read(¤t->request_key_auth->sem); | |
3e30148c | 173 | } |
b5f545c8 DH |
174 | else { |
175 | /* it isn't - use this process as the context */ | |
176 | rka->context = current; | |
177 | rka->pid = current->pid; | |
04c567d9 | 178 | get_task_struct(rka->context); |
b5f545c8 DH |
179 | } |
180 | ||
181 | rka->target_key = key_get(target); | |
182 | rka->callout_info = callout_info; | |
3e30148c DH |
183 | |
184 | /* allocate the auth key */ | |
185 | sprintf(desc, "%x", target->serial); | |
186 | ||
b5f545c8 | 187 | authkey = key_alloc(&key_type_request_key_auth, desc, |
d720024e | 188 | current->fsuid, current->fsgid, current, |
b5f545c8 | 189 | KEY_POS_VIEW | KEY_POS_READ | KEY_POS_SEARCH | |
7e047ef5 | 190 | KEY_USR_VIEW, KEY_ALLOC_NOT_IN_QUOTA); |
b5f545c8 DH |
191 | if (IS_ERR(authkey)) { |
192 | ret = PTR_ERR(authkey); | |
193 | goto error_alloc; | |
3e30148c DH |
194 | } |
195 | ||
196 | /* construct and attach to the keyring */ | |
b5f545c8 DH |
197 | ret = key_instantiate_and_link(authkey, rka, 0, NULL, NULL); |
198 | if (ret < 0) | |
199 | goto error_inst; | |
3e30148c | 200 | |
04c567d9 | 201 | kleave(" = {%d}", authkey->serial); |
b5f545c8 DH |
202 | return authkey; |
203 | ||
04c567d9 DH |
204 | auth_key_revoked: |
205 | up_read(¤t->request_key_auth->sem); | |
206 | kfree(rka); | |
207 | kleave("= -EKEYREVOKED"); | |
208 | return ERR_PTR(-EKEYREVOKED); | |
209 | ||
b5f545c8 DH |
210 | error_inst: |
211 | key_revoke(authkey); | |
212 | key_put(authkey); | |
213 | error_alloc: | |
214 | key_put(rka->target_key); | |
215 | kfree(rka); | |
216 | kleave("= %d", ret); | |
217 | return ERR_PTR(ret); | |
3e30148c DH |
218 | |
219 | } /* end request_key_auth_new() */ | |
220 | ||
b5f545c8 DH |
221 | /*****************************************************************************/ |
222 | /* | |
223 | * see if an authorisation key is associated with a particular key | |
224 | */ | |
225 | static int key_get_instantiation_authkey_match(const struct key *key, | |
226 | const void *_id) | |
227 | { | |
228 | struct request_key_auth *rka = key->payload.data; | |
229 | key_serial_t id = (key_serial_t)(unsigned long) _id; | |
230 | ||
231 | return rka->target_key->serial == id; | |
232 | ||
233 | } /* end key_get_instantiation_authkey_match() */ | |
234 | ||
3e30148c DH |
235 | /*****************************************************************************/ |
236 | /* | |
237 | * get the authorisation key for instantiation of a specific key if attached to | |
238 | * the current process's keyrings | |
239 | * - this key is inserted into a keyring and that is set as /sbin/request-key's | |
240 | * session keyring | |
241 | * - a target_id of zero specifies any valid token | |
242 | */ | |
243 | struct key *key_get_instantiation_authkey(key_serial_t target_id) | |
244 | { | |
b5f545c8 DH |
245 | struct key *authkey; |
246 | key_ref_t authkey_ref; | |
247 | ||
248 | authkey_ref = search_process_keyrings( | |
249 | &key_type_request_key_auth, | |
250 | (void *) (unsigned long) target_id, | |
251 | key_get_instantiation_authkey_match, | |
252 | current); | |
253 | ||
254 | if (IS_ERR(authkey_ref)) { | |
255 | authkey = ERR_PTR(PTR_ERR(authkey_ref)); | |
256 | goto error; | |
257 | } | |
3e30148c | 258 | |
b5f545c8 DH |
259 | authkey = key_ref_to_ptr(authkey_ref); |
260 | if (test_bit(KEY_FLAG_REVOKED, &authkey->flags)) { | |
261 | key_put(authkey); | |
262 | authkey = ERR_PTR(-EKEYREVOKED); | |
263 | } | |
3e30148c | 264 | |
b5f545c8 DH |
265 | error: |
266 | return authkey; | |
3e30148c DH |
267 | |
268 | } /* end key_get_instantiation_authkey() */ |