1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /* Request key authorisation token key definition.
4 * Copyright (C) 2005 Red Hat, Inc. All Rights Reserved.
5 * Written by David Howells (dhowells@redhat.com)
7 * See Documentation/security/keys/request-key.rst
10 #include <linux/sched.h>
11 #include <linux/err.h>
12 #include <linux/seq_file.h>
13 #include <linux/slab.h>
14 #include <linux/uaccess.h>
16 #include <keys/request_key_auth-type.h>
18 static int request_key_auth_preparse(struct key_preparsed_payload *);
19 static void request_key_auth_free_preparse(struct key_preparsed_payload *);
20 static int request_key_auth_instantiate(struct key *,
21 struct key_preparsed_payload *);
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 .preparse = request_key_auth_preparse,
34 .free_preparse = request_key_auth_free_preparse,
35 .instantiate = request_key_auth_instantiate,
36 .describe = request_key_auth_describe,
37 .revoke = request_key_auth_revoke,
38 .destroy = request_key_auth_destroy,
39 .read = request_key_auth_read,
42 static int request_key_auth_preparse(struct key_preparsed_payload *prep)
47 static void request_key_auth_free_preparse(struct key_preparsed_payload *prep)
52 * Instantiate a request-key authorisation key.
54 static int request_key_auth_instantiate(struct key *key,
55 struct key_preparsed_payload *prep)
57 key->payload.data[0] = (struct request_key_auth *)prep->data;
62 * Describe an authorisation token.
64 static void request_key_auth_describe(const struct key *key,
67 struct request_key_auth *rka = get_request_key_auth(key);
70 seq_puts(m, key->description);
71 if (key_is_positive(key))
72 seq_printf(m, " pid:%d ci:%zu", rka->pid, rka->callout_len);
76 * Read the callout_info data (retrieves the callout information).
77 * - the key's semaphore is read-locked
79 static long request_key_auth_read(const struct key *key,
80 char __user *buffer, size_t buflen)
82 struct request_key_auth *rka = get_request_key_auth(key);
86 datalen = rka->callout_len;
89 /* we can return the data as is */
90 if (buffer && buflen > 0) {
94 if (copy_to_user(buffer, rka->callout_info, buflen) != 0)
102 * Handle revocation of an authorisation token key.
104 * Called with the key sem write-locked.
106 static void request_key_auth_revoke(struct key *key)
108 struct request_key_auth *rka = get_request_key_auth(key);
110 kenter("{%d}", key->serial);
118 static void free_request_key_auth(struct request_key_auth *rka)
122 key_put(rka->target_key);
123 key_put(rka->dest_keyring);
126 kfree(rka->callout_info);
131 * Destroy an instantiation authorisation token key.
133 static void request_key_auth_destroy(struct key *key)
135 struct request_key_auth *rka = get_request_key_auth(key);
137 kenter("{%d}", key->serial);
139 free_request_key_auth(rka);
143 * Create an authorisation token for /sbin/request-key or whoever to gain
144 * access to the caller's security data.
146 struct key *request_key_auth_new(struct key *target, const char *op,
147 const void *callout_info, size_t callout_len,
148 struct key *dest_keyring)
150 struct request_key_auth *rka, *irka;
151 const struct cred *cred = current->cred;
152 struct key *authkey = NULL;
156 kenter("%d,", target->serial);
158 /* allocate a auth record */
159 rka = kzalloc(sizeof(*rka), GFP_KERNEL);
162 rka->callout_info = kmemdup(callout_info, callout_len, GFP_KERNEL);
163 if (!rka->callout_info)
165 rka->callout_len = callout_len;
166 strlcpy(rka->op, op, sizeof(rka->op));
168 /* see if the calling process is already servicing the key request of
170 if (cred->request_key_auth) {
171 /* it is - use that instantiation context here too */
172 down_read(&cred->request_key_auth->sem);
174 /* if the auth key has been revoked, then the key we're
175 * servicing is already instantiated */
176 if (test_bit(KEY_FLAG_REVOKED,
177 &cred->request_key_auth->flags)) {
178 up_read(&cred->request_key_auth->sem);
183 irka = cred->request_key_auth->payload.data[0];
184 rka->cred = get_cred(irka->cred);
185 rka->pid = irka->pid;
187 up_read(&cred->request_key_auth->sem);
190 /* it isn't - use this process as the context */
191 rka->cred = get_cred(cred);
192 rka->pid = current->pid;
195 rka->target_key = key_get(target);
196 rka->dest_keyring = key_get(dest_keyring);
198 /* allocate the auth key */
199 sprintf(desc, "%x", target->serial);
201 authkey = key_alloc(&key_type_request_key_auth, desc,
202 cred->fsuid, cred->fsgid, cred,
203 KEY_POS_VIEW | KEY_POS_READ | KEY_POS_SEARCH |
204 KEY_USR_VIEW, KEY_ALLOC_NOT_IN_QUOTA, NULL);
205 if (IS_ERR(authkey)) {
206 ret = PTR_ERR(authkey);
210 /* construct the auth key */
211 ret = key_instantiate_and_link(authkey, rka, 0, NULL, NULL);
213 goto error_put_authkey;
215 kleave(" = {%d,%d}", authkey->serial, refcount_read(&authkey->usage));
221 free_request_key_auth(rka);
228 * Search the current process's keyrings for the authorisation key for
229 * instantiation of a key.
231 struct key *key_get_instantiation_authkey(key_serial_t target_id)
233 char description[16];
234 struct keyring_search_context ctx = {
235 .index_key.type = &key_type_request_key_auth,
236 .index_key.description = description,
237 .cred = current_cred(),
238 .match_data.cmp = key_default_cmp,
239 .match_data.raw_data = description,
240 .match_data.lookup_type = KEYRING_SEARCH_LOOKUP_DIRECT,
241 .flags = KEYRING_SEARCH_DO_STATE_CHECK,
244 key_ref_t authkey_ref;
246 ctx.index_key.desc_len = sprintf(description, "%x", target_id);
248 authkey_ref = search_process_keyrings(&ctx);
250 if (IS_ERR(authkey_ref)) {
251 authkey = ERR_CAST(authkey_ref);
252 if (authkey == ERR_PTR(-EAGAIN))
253 authkey = ERR_PTR(-ENOKEY);
257 authkey = key_ref_to_ptr(authkey_ref);
258 if (test_bit(KEY_FLAG_REVOKED, &authkey->flags)) {
260 authkey = ERR_PTR(-EKEYREVOKED);