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>
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,
48 key->payload.data = (struct request_key_auth *) data;
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,
60 struct request_key_auth *rka = key->payload.data;
63 seq_puts(m, key->description);
64 seq_printf(m, " pid:%d ci:%zu", rka->pid, rka->callout_len);
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;
80 datalen = rka->callout_len;
83 /* we can return the data as is */
84 if (buffer && buflen > 0) {
88 if (copy_to_user(buffer, rka->callout_info, buflen) != 0)
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);
108 put_task_struct(rka->context);
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);
125 put_task_struct(rka->context);
129 key_put(rka->target_key);
130 kfree(rka->callout_info);
133 } /* end request_key_auth_destroy() */
135 /*****************************************************************************/
137 * create an authorisation token for /sbin/request-key or whoever to gain
138 * access to the caller's security data
140 struct key *request_key_auth_new(struct key *target, const void *callout_info,
143 struct request_key_auth *rka, *irka;
144 struct key *authkey = NULL;
148 kenter("%d,", target->serial);
150 /* allocate a auth record */
151 rka = kmalloc(sizeof(*rka), GFP_KERNEL);
153 kleave(" = -ENOMEM");
154 return ERR_PTR(-ENOMEM);
156 rka->callout_info = kmalloc(callout_len, GFP_KERNEL);
157 if (!rka->callout_info) {
158 kleave(" = -ENOMEM");
160 return ERR_PTR(-ENOMEM);
163 /* see if the calling process is already servicing the key request of
165 if (current->request_key_auth) {
166 /* it is - use that instantiation context here too */
167 down_read(¤t->request_key_auth->sem);
169 /* if the auth key has been revoked, then the key we're
170 * servicing is already instantiated */
171 if (test_bit(KEY_FLAG_REVOKED,
172 ¤t->request_key_auth->flags))
173 goto auth_key_revoked;
175 irka = current->request_key_auth->payload.data;
176 rka->context = irka->context;
177 rka->pid = irka->pid;
178 get_task_struct(rka->context);
180 up_read(¤t->request_key_auth->sem);
183 /* it isn't - use this process as the context */
184 rka->context = current;
185 rka->pid = current->pid;
186 get_task_struct(rka->context);
189 rka->target_key = key_get(target);
190 memcpy(rka->callout_info, callout_info, callout_len);
191 rka->callout_len = callout_len;
193 /* allocate the auth key */
194 sprintf(desc, "%x", target->serial);
196 authkey = key_alloc(&key_type_request_key_auth, desc,
197 current->fsuid, current->fsgid, current,
198 KEY_POS_VIEW | KEY_POS_READ | KEY_POS_SEARCH |
199 KEY_USR_VIEW, KEY_ALLOC_NOT_IN_QUOTA);
200 if (IS_ERR(authkey)) {
201 ret = PTR_ERR(authkey);
205 /* construct and attach to the keyring */
206 ret = key_instantiate_and_link(authkey, rka, 0, NULL, NULL);
210 kleave(" = {%d}", authkey->serial);
214 up_read(¤t->request_key_auth->sem);
215 kfree(rka->callout_info);
217 kleave("= -EKEYREVOKED");
218 return ERR_PTR(-EKEYREVOKED);
224 key_put(rka->target_key);
225 kfree(rka->callout_info);
230 } /* end request_key_auth_new() */
232 /*****************************************************************************/
234 * see if an authorisation key is associated with a particular key
236 static int key_get_instantiation_authkey_match(const struct key *key,
239 struct request_key_auth *rka = key->payload.data;
240 key_serial_t id = (key_serial_t)(unsigned long) _id;
242 return rka->target_key->serial == id;
244 } /* end key_get_instantiation_authkey_match() */
246 /*****************************************************************************/
248 * get the authorisation key for instantiation of a specific key if attached to
249 * the current process's keyrings
250 * - this key is inserted into a keyring and that is set as /sbin/request-key's
252 * - a target_id of zero specifies any valid token
254 struct key *key_get_instantiation_authkey(key_serial_t target_id)
257 key_ref_t authkey_ref;
259 authkey_ref = search_process_keyrings(
260 &key_type_request_key_auth,
261 (void *) (unsigned long) target_id,
262 key_get_instantiation_authkey_match,
265 if (IS_ERR(authkey_ref)) {
266 authkey = ERR_CAST(authkey_ref);
270 authkey = key_ref_to_ptr(authkey_ref);
271 if (test_bit(KEY_FLAG_REVOKED, &authkey->flags)) {
273 authkey = ERR_PTR(-EKEYREVOKED);
279 } /* end key_get_instantiation_authkey() */