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