fs: use kmem_cache_zalloc instead
[pv_ops_mirror.git] / security / keys / request_key_auth.c
blobcbf58a91b00a4c945ec72ca7db2867c19548dd6c
1 /* request_key_auth.c: request key authorisation controlling key def
3 * Copyright (C) 2005 Red Hat, Inc. All Rights Reserved.
4 * Written by David Howells (dhowells@redhat.com)
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.
11 * See Documentation/keys-request-key.txt
14 #include <linux/module.h>
15 #include <linux/sched.h>
16 #include <linux/err.h>
17 #include <linux/seq_file.h>
18 #include <asm/uaccess.h>
19 #include "internal.h"
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 *);
23 static void request_key_auth_revoke(struct key *);
24 static void request_key_auth_destroy(struct key *);
25 static long request_key_auth_read(const struct key *, char __user *, size_t);
28 * the request-key authorisation key type definition
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,
35 .revoke = request_key_auth_revoke,
36 .destroy = request_key_auth_destroy,
37 .read = request_key_auth_read,
40 /*****************************************************************************/
42 * instantiate a request-key authorisation key
44 static int request_key_auth_instantiate(struct key *key,
45 const void *data,
46 size_t datalen)
48 key->payload.data = (struct request_key_auth *) data;
49 return 0;
51 } /* end request_key_auth_instantiate() */
53 /*****************************************************************************/
55 * reading a request-key authorisation key retrieves the callout information
57 static void request_key_auth_describe(const struct key *key,
58 struct seq_file *m)
60 struct request_key_auth *rka = key->payload.data;
62 seq_puts(m, "key:");
63 seq_puts(m, key->description);
64 seq_printf(m, " pid:%d ci:%zu", rka->pid, strlen(rka->callout_info));
66 } /* end request_key_auth_describe() */
68 /*****************************************************************************/
70 * read the callout_info data
71 * - the key's semaphore is read-locked
73 static long request_key_auth_read(const struct key *key,
74 char __user *buffer, size_t buflen)
76 struct request_key_auth *rka = key->payload.data;
77 size_t datalen;
78 long ret;
80 datalen = strlen(rka->callout_info);
81 ret = datalen;
83 /* we can return the data as is */
84 if (buffer && buflen > 0) {
85 if (buflen > datalen)
86 buflen = datalen;
88 if (copy_to_user(buffer, rka->callout_info, buflen) != 0)
89 ret = -EFAULT;
92 return ret;
94 } /* end request_key_auth_read() */
96 /*****************************************************************************/
98 * handle revocation of an authorisation token key
99 * - called with the key sem write-locked
101 static void request_key_auth_revoke(struct key *key)
103 struct request_key_auth *rka = key->payload.data;
105 kenter("{%d}", key->serial);
107 if (rka->context) {
108 put_task_struct(rka->context);
109 rka->context = NULL;
112 } /* end request_key_auth_revoke() */
114 /*****************************************************************************/
116 * destroy an instantiation authorisation token key
118 static void request_key_auth_destroy(struct key *key)
120 struct request_key_auth *rka = key->payload.data;
122 kenter("{%d}", key->serial);
124 if (rka->context) {
125 put_task_struct(rka->context);
126 rka->context = NULL;
129 key_put(rka->target_key);
130 kfree(rka);
132 } /* end request_key_auth_destroy() */
134 /*****************************************************************************/
136 * create an authorisation token for /sbin/request-key or whoever to gain
137 * access to the caller's security data
139 struct key *request_key_auth_new(struct key *target, const char *callout_info)
141 struct request_key_auth *rka, *irka;
142 struct key *authkey = NULL;
143 char desc[20];
144 int ret;
146 kenter("%d,", target->serial);
148 /* allocate a auth record */
149 rka = kmalloc(sizeof(*rka), GFP_KERNEL);
150 if (!rka) {
151 kleave(" = -ENOMEM");
152 return ERR_PTR(-ENOMEM);
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 */
159 down_read(&current->request_key_auth->sem);
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 &current->request_key_auth->flags))
165 goto auth_key_revoked;
167 irka = current->request_key_auth->payload.data;
168 rka->context = irka->context;
169 rka->pid = irka->pid;
170 get_task_struct(rka->context);
172 up_read(&current->request_key_auth->sem);
174 else {
175 /* it isn't - use this process as the context */
176 rka->context = current;
177 rka->pid = current->pid;
178 get_task_struct(rka->context);
181 rka->target_key = key_get(target);
182 rka->callout_info = callout_info;
184 /* allocate the auth key */
185 sprintf(desc, "%x", target->serial);
187 authkey = key_alloc(&key_type_request_key_auth, desc,
188 current->fsuid, current->fsgid, current,
189 KEY_POS_VIEW | KEY_POS_READ | KEY_POS_SEARCH |
190 KEY_USR_VIEW, KEY_ALLOC_NOT_IN_QUOTA);
191 if (IS_ERR(authkey)) {
192 ret = PTR_ERR(authkey);
193 goto error_alloc;
196 /* construct and attach to the keyring */
197 ret = key_instantiate_and_link(authkey, rka, 0, NULL, NULL);
198 if (ret < 0)
199 goto error_inst;
201 kleave(" = {%d}", authkey->serial);
202 return authkey;
204 auth_key_revoked:
205 up_read(&current->request_key_auth->sem);
206 kfree(rka);
207 kleave("= -EKEYREVOKED");
208 return ERR_PTR(-EKEYREVOKED);
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);
219 } /* end request_key_auth_new() */
221 /*****************************************************************************/
223 * see if an authorisation key is associated with a particular key
225 static int key_get_instantiation_authkey_match(const struct key *key,
226 const void *_id)
228 struct request_key_auth *rka = key->payload.data;
229 key_serial_t id = (key_serial_t)(unsigned long) _id;
231 return rka->target_key->serial == id;
233 } /* end key_get_instantiation_authkey_match() */
235 /*****************************************************************************/
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
243 struct key *key_get_instantiation_authkey(key_serial_t target_id)
245 struct key *authkey;
246 key_ref_t authkey_ref;
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);
254 if (IS_ERR(authkey_ref)) {
255 authkey = ERR_PTR(PTR_ERR(authkey_ref));
256 goto error;
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);
265 error:
266 return authkey;
268 } /* end key_get_instantiation_authkey() */