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 <linux/slab.h>
19 #include <asm/uaccess.h>
22 static int request_key_auth_instantiate(struct key *, const void *, size_t);
23 static void request_key_auth_describe(const struct key *, struct seq_file *);
24 static void request_key_auth_revoke(struct key *);
25 static void request_key_auth_destroy(struct key *);
26 static long request_key_auth_read(const struct key *, char __user *, size_t);
29 * the request-key authorisation key type definition
31 struct key_type key_type_request_key_auth = {
32 .name = ".request_key_auth",
33 .def_datalen = sizeof(struct request_key_auth),
34 .instantiate = request_key_auth_instantiate,
35 .describe = request_key_auth_describe,
36 .revoke = request_key_auth_revoke,
37 .destroy = request_key_auth_destroy,
38 .read = request_key_auth_read,
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;
53 * reading a request-key authorisation key retrieves the callout information
55 static void request_key_auth_describe(const struct key *key,
58 struct request_key_auth *rka = key->payload.data;
61 seq_puts(m, key->description);
62 seq_printf(m, " pid:%d ci:%zu", rka->pid, rka->callout_len);
66 * read the callout_info data
67 * - the key's semaphore is read-locked
69 static long request_key_auth_read(const struct key *key,
70 char __user *buffer, size_t buflen)
72 struct request_key_auth *rka = key->payload.data;
76 datalen = rka->callout_len;
79 /* we can return the data as is */
80 if (buffer && buflen > 0) {
84 if (copy_to_user(buffer, rka->callout_info, buflen) != 0)
92 * handle revocation of an authorisation token key
93 * - called with the key sem write-locked
95 static void request_key_auth_revoke(struct key *key)
97 struct request_key_auth *rka = key->payload.data;
99 kenter("{%d}", key->serial);
108 * destroy an instantiation authorisation token key
110 static void request_key_auth_destroy(struct key *key)
112 struct request_key_auth *rka = key->payload.data;
114 kenter("{%d}", key->serial);
121 key_put(rka->target_key);
122 key_put(rka->dest_keyring);
123 kfree(rka->callout_info);
128 * create an authorisation token for /sbin/request-key or whoever to gain
129 * access to the caller's security data
131 struct key *request_key_auth_new(struct key *target, const void *callout_info,
132 size_t callout_len, struct key *dest_keyring)
134 struct request_key_auth *rka, *irka;
135 const struct cred *cred = current->cred;
136 struct key *authkey = NULL;
140 kenter("%d,", target->serial);
142 /* allocate a auth record */
143 rka = kmalloc(sizeof(*rka), GFP_KERNEL);
145 kleave(" = -ENOMEM");
146 return ERR_PTR(-ENOMEM);
148 rka->callout_info = kmalloc(callout_len, GFP_KERNEL);
149 if (!rka->callout_info) {
150 kleave(" = -ENOMEM");
152 return ERR_PTR(-ENOMEM);
155 /* see if the calling process is already servicing the key request of
157 if (cred->request_key_auth) {
158 /* it is - use that instantiation context here too */
159 down_read(&cred->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, &cred->request_key_auth->flags))
164 goto auth_key_revoked;
166 irka = cred->request_key_auth->payload.data;
167 rka->cred = get_cred(irka->cred);
168 rka->pid = irka->pid;
170 up_read(&cred->request_key_auth->sem);
173 /* it isn't - use this process as the context */
174 rka->cred = get_cred(cred);
175 rka->pid = current->pid;
178 rka->target_key = key_get(target);
179 rka->dest_keyring = key_get(dest_keyring);
180 memcpy(rka->callout_info, callout_info, callout_len);
181 rka->callout_len = callout_len;
183 /* allocate the auth key */
184 sprintf(desc, "%x", target->serial);
186 authkey = key_alloc(&key_type_request_key_auth, desc,
187 cred->fsuid, cred->fsgid, cred,
188 KEY_POS_VIEW | KEY_POS_READ | KEY_POS_SEARCH |
189 KEY_USR_VIEW, KEY_ALLOC_NOT_IN_QUOTA);
190 if (IS_ERR(authkey)) {
191 ret = PTR_ERR(authkey);
195 /* construct the auth key */
196 ret = key_instantiate_and_link(authkey, rka, 0, NULL, NULL);
200 kleave(" = {%d,%d}", authkey->serial, atomic_read(&authkey->usage));
204 up_read(&cred->request_key_auth->sem);
205 kfree(rka->callout_info);
207 kleave("= -EKEYREVOKED");
208 return ERR_PTR(-EKEYREVOKED);
214 key_put(rka->target_key);
215 key_put(rka->dest_keyring);
216 kfree(rka->callout_info);
223 * see if an authorisation key is associated with a particular key
225 static int key_get_instantiation_authkey_match(const struct key *key,
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;
235 * get the authorisation key for instantiation of a specific key if attached to
236 * the current process's keyrings
237 * - this key is inserted into a keyring and that is set as /sbin/request-key's
239 * - a target_id of zero specifies any valid token
241 struct key *key_get_instantiation_authkey(key_serial_t target_id)
243 const struct cred *cred = current_cred();
245 key_ref_t authkey_ref;
247 authkey_ref = search_process_keyrings(
248 &key_type_request_key_auth,
249 (void *) (unsigned long) target_id,
250 key_get_instantiation_authkey_match,
253 if (IS_ERR(authkey_ref)) {
254 authkey = ERR_CAST(authkey_ref);
258 authkey = key_ref_to_ptr(authkey_ref);
259 if (test_bit(KEY_FLAG_REVOKED, &authkey->flags)) {
261 authkey = ERR_PTR(-EKEYREVOKED);