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3e30148c DH |
1 | /* request_key_auth.c: request key authorisation controlling key def |
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. | |
f1a9badc DH |
10 | * |
11 | * See Documentation/keys-request-key.txt | |
3e30148c DH |
12 | */ |
13 | ||
14 | #include <linux/module.h> | |
15 | #include <linux/sched.h> | |
16 | #include <linux/err.h> | |
17 | #include <linux/seq_file.h> | |
fdb89bce | 18 | #include <linux/slab.h> |
b5f545c8 | 19 | #include <asm/uaccess.h> |
3e30148c DH |
20 | #include "internal.h" |
21 | ||
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 *); | |
04c567d9 | 24 | static void request_key_auth_revoke(struct key *); |
3e30148c | 25 | static void request_key_auth_destroy(struct key *); |
b5f545c8 | 26 | static long request_key_auth_read(const struct key *, char __user *, size_t); |
3e30148c DH |
27 | |
28 | /* | |
29 | * the request-key authorisation key type definition | |
30 | */ | |
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, | |
04c567d9 | 36 | .revoke = request_key_auth_revoke, |
3e30148c | 37 | .destroy = request_key_auth_destroy, |
b5f545c8 | 38 | .read = request_key_auth_read, |
3e30148c DH |
39 | }; |
40 | ||
3e30148c | 41 | /* |
b5f545c8 | 42 | * instantiate a request-key authorisation key |
3e30148c DH |
43 | */ |
44 | static int request_key_auth_instantiate(struct key *key, | |
45 | const void *data, | |
46 | size_t datalen) | |
47 | { | |
b5f545c8 DH |
48 | key->payload.data = (struct request_key_auth *) data; |
49 | return 0; | |
a8b17ed0 | 50 | } |
3e30148c | 51 | |
3e30148c | 52 | /* |
b5f545c8 | 53 | * reading a request-key authorisation key retrieves the callout information |
3e30148c DH |
54 | */ |
55 | static void request_key_auth_describe(const struct key *key, | |
56 | struct seq_file *m) | |
57 | { | |
58 | struct request_key_auth *rka = key->payload.data; | |
59 | ||
60 | seq_puts(m, "key:"); | |
61 | seq_puts(m, key->description); | |
4a38e122 | 62 | seq_printf(m, " pid:%d ci:%zu", rka->pid, rka->callout_len); |
a8b17ed0 | 63 | } |
3e30148c | 64 | |
b5f545c8 DH |
65 | /* |
66 | * read the callout_info data | |
67 | * - the key's semaphore is read-locked | |
68 | */ | |
69 | static long request_key_auth_read(const struct key *key, | |
70 | char __user *buffer, size_t buflen) | |
71 | { | |
72 | struct request_key_auth *rka = key->payload.data; | |
73 | size_t datalen; | |
74 | long ret; | |
75 | ||
4a38e122 | 76 | datalen = rka->callout_len; |
b5f545c8 DH |
77 | ret = datalen; |
78 | ||
79 | /* we can return the data as is */ | |
80 | if (buffer && buflen > 0) { | |
81 | if (buflen > datalen) | |
82 | buflen = datalen; | |
83 | ||
84 | if (copy_to_user(buffer, rka->callout_info, buflen) != 0) | |
85 | ret = -EFAULT; | |
86 | } | |
87 | ||
88 | return ret; | |
a8b17ed0 | 89 | } |
b5f545c8 | 90 | |
04c567d9 DH |
91 | /* |
92 | * handle revocation of an authorisation token key | |
93 | * - called with the key sem write-locked | |
94 | */ | |
95 | static void request_key_auth_revoke(struct key *key) | |
96 | { | |
97 | struct request_key_auth *rka = key->payload.data; | |
98 | ||
99 | kenter("{%d}", key->serial); | |
100 | ||
d84f4f99 DH |
101 | if (rka->cred) { |
102 | put_cred(rka->cred); | |
103 | rka->cred = NULL; | |
04c567d9 | 104 | } |
a8b17ed0 | 105 | } |
04c567d9 | 106 | |
3e30148c DH |
107 | /* |
108 | * destroy an instantiation authorisation token key | |
109 | */ | |
110 | static void request_key_auth_destroy(struct key *key) | |
111 | { | |
112 | struct request_key_auth *rka = key->payload.data; | |
113 | ||
114 | kenter("{%d}", key->serial); | |
115 | ||
d84f4f99 DH |
116 | if (rka->cred) { |
117 | put_cred(rka->cred); | |
118 | rka->cred = NULL; | |
04c567d9 DH |
119 | } |
120 | ||
3e30148c | 121 | key_put(rka->target_key); |
8bbf4976 | 122 | key_put(rka->dest_keyring); |
76181c13 | 123 | kfree(rka->callout_info); |
74fd92c5 | 124 | kfree(rka); |
a8b17ed0 | 125 | } |
3e30148c | 126 | |
3e30148c | 127 | /* |
b5f545c8 DH |
128 | * create an authorisation token for /sbin/request-key or whoever to gain |
129 | * access to the caller's security data | |
3e30148c | 130 | */ |
4a38e122 | 131 | struct key *request_key_auth_new(struct key *target, const void *callout_info, |
8bbf4976 | 132 | size_t callout_len, struct key *dest_keyring) |
3e30148c | 133 | { |
b5f545c8 | 134 | struct request_key_auth *rka, *irka; |
d84f4f99 | 135 | const struct cred *cred = current->cred; |
b5f545c8 | 136 | struct key *authkey = NULL; |
3e30148c DH |
137 | char desc[20]; |
138 | int ret; | |
139 | ||
140 | kenter("%d,", target->serial); | |
141 | ||
b5f545c8 DH |
142 | /* allocate a auth record */ |
143 | rka = kmalloc(sizeof(*rka), GFP_KERNEL); | |
144 | if (!rka) { | |
145 | kleave(" = -ENOMEM"); | |
146 | return ERR_PTR(-ENOMEM); | |
147 | } | |
4a38e122 | 148 | rka->callout_info = kmalloc(callout_len, GFP_KERNEL); |
76181c13 DH |
149 | if (!rka->callout_info) { |
150 | kleave(" = -ENOMEM"); | |
151 | kfree(rka); | |
152 | return ERR_PTR(-ENOMEM); | |
153 | } | |
3e30148c | 154 | |
b5f545c8 DH |
155 | /* see if the calling process is already servicing the key request of |
156 | * another process */ | |
d84f4f99 | 157 | if (cred->request_key_auth) { |
b5f545c8 | 158 | /* it is - use that instantiation context here too */ |
d84f4f99 | 159 | down_read(&cred->request_key_auth->sem); |
04c567d9 DH |
160 | |
161 | /* if the auth key has been revoked, then the key we're | |
162 | * servicing is already instantiated */ | |
d84f4f99 | 163 | if (test_bit(KEY_FLAG_REVOKED, &cred->request_key_auth->flags)) |
04c567d9 DH |
164 | goto auth_key_revoked; |
165 | ||
d84f4f99 DH |
166 | irka = cred->request_key_auth->payload.data; |
167 | rka->cred = get_cred(irka->cred); | |
b5f545c8 | 168 | rka->pid = irka->pid; |
04c567d9 | 169 | |
d84f4f99 | 170 | up_read(&cred->request_key_auth->sem); |
3e30148c | 171 | } |
b5f545c8 DH |
172 | else { |
173 | /* it isn't - use this process as the context */ | |
d84f4f99 | 174 | rka->cred = get_cred(cred); |
b5f545c8 DH |
175 | rka->pid = current->pid; |
176 | } | |
177 | ||
178 | rka->target_key = key_get(target); | |
8bbf4976 | 179 | rka->dest_keyring = key_get(dest_keyring); |
4a38e122 DH |
180 | memcpy(rka->callout_info, callout_info, callout_len); |
181 | rka->callout_len = callout_len; | |
3e30148c DH |
182 | |
183 | /* allocate the auth key */ | |
184 | sprintf(desc, "%x", target->serial); | |
185 | ||
b5f545c8 | 186 | authkey = key_alloc(&key_type_request_key_auth, desc, |
d84f4f99 | 187 | cred->fsuid, cred->fsgid, cred, |
b5f545c8 | 188 | KEY_POS_VIEW | KEY_POS_READ | KEY_POS_SEARCH | |
7e047ef5 | 189 | KEY_USR_VIEW, KEY_ALLOC_NOT_IN_QUOTA); |
b5f545c8 DH |
190 | if (IS_ERR(authkey)) { |
191 | ret = PTR_ERR(authkey); | |
192 | goto error_alloc; | |
3e30148c DH |
193 | } |
194 | ||
d84f4f99 | 195 | /* construct the auth key */ |
b5f545c8 DH |
196 | ret = key_instantiate_and_link(authkey, rka, 0, NULL, NULL); |
197 | if (ret < 0) | |
198 | goto error_inst; | |
3e30148c | 199 | |
d84f4f99 | 200 | kleave(" = {%d,%d}", authkey->serial, atomic_read(&authkey->usage)); |
b5f545c8 DH |
201 | return authkey; |
202 | ||
04c567d9 | 203 | auth_key_revoked: |
d84f4f99 | 204 | up_read(&cred->request_key_auth->sem); |
76181c13 | 205 | kfree(rka->callout_info); |
04c567d9 DH |
206 | kfree(rka); |
207 | kleave("= -EKEYREVOKED"); | |
208 | return ERR_PTR(-EKEYREVOKED); | |
209 | ||
b5f545c8 DH |
210 | error_inst: |
211 | key_revoke(authkey); | |
212 | key_put(authkey); | |
213 | error_alloc: | |
214 | key_put(rka->target_key); | |
8bbf4976 | 215 | key_put(rka->dest_keyring); |
76181c13 | 216 | kfree(rka->callout_info); |
b5f545c8 DH |
217 | kfree(rka); |
218 | kleave("= %d", ret); | |
219 | return ERR_PTR(ret); | |
a8b17ed0 | 220 | } |
3e30148c | 221 | |
b5f545c8 DH |
222 | /* |
223 | * see if an authorisation key is associated with a particular key | |
224 | */ | |
225 | static int key_get_instantiation_authkey_match(const struct key *key, | |
226 | const void *_id) | |
227 | { | |
228 | struct request_key_auth *rka = key->payload.data; | |
229 | key_serial_t id = (key_serial_t)(unsigned long) _id; | |
230 | ||
231 | return rka->target_key->serial == id; | |
a8b17ed0 | 232 | } |
b5f545c8 | 233 | |
3e30148c DH |
234 | /* |
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 | |
238 | * session keyring | |
239 | * - a target_id of zero specifies any valid token | |
240 | */ | |
241 | struct key *key_get_instantiation_authkey(key_serial_t target_id) | |
242 | { | |
d84f4f99 | 243 | const struct cred *cred = current_cred(); |
b5f545c8 DH |
244 | struct key *authkey; |
245 | key_ref_t authkey_ref; | |
246 | ||
247 | authkey_ref = search_process_keyrings( | |
248 | &key_type_request_key_auth, | |
249 | (void *) (unsigned long) target_id, | |
250 | key_get_instantiation_authkey_match, | |
d84f4f99 | 251 | cred); |
b5f545c8 DH |
252 | |
253 | if (IS_ERR(authkey_ref)) { | |
e231c2ee | 254 | authkey = ERR_CAST(authkey_ref); |
b5f545c8 DH |
255 | goto error; |
256 | } | |
3e30148c | 257 | |
b5f545c8 DH |
258 | authkey = key_ref_to_ptr(authkey_ref); |
259 | if (test_bit(KEY_FLAG_REVOKED, &authkey->flags)) { | |
260 | key_put(authkey); | |
261 | authkey = ERR_PTR(-EKEYREVOKED); | |
262 | } | |
3e30148c | 263 | |
b5f545c8 DH |
264 | error: |
265 | return authkey; | |
a8b17ed0 | 266 | } |