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2874c5fd | 1 | // SPDX-License-Identifier: GPL-2.0-or-later |
973c9f4f | 2 | /* Request key authorisation token key definition. |
3e30148c DH |
3 | * |
4 | * Copyright (C) 2005 Red Hat, Inc. All Rights Reserved. | |
5 | * Written by David Howells (dhowells@redhat.com) | |
6 | * | |
3db38ed7 | 7 | * See Documentation/security/keys/request-key.rst |
3e30148c DH |
8 | */ |
9 | ||
3e30148c DH |
10 | #include <linux/sched.h> |
11 | #include <linux/err.h> | |
12 | #include <linux/seq_file.h> | |
fdb89bce | 13 | #include <linux/slab.h> |
7c0f6ba6 | 14 | #include <linux/uaccess.h> |
3e30148c | 15 | #include "internal.h" |
822ad64d | 16 | #include <keys/request_key_auth-type.h> |
3e30148c | 17 | |
f1dcde91 DH |
18 | static int request_key_auth_preparse(struct key_preparsed_payload *); |
19 | static void request_key_auth_free_preparse(struct key_preparsed_payload *); | |
cf7f601c DH |
20 | static int request_key_auth_instantiate(struct key *, |
21 | struct key_preparsed_payload *); | |
3e30148c | 22 | static void request_key_auth_describe(const struct key *, struct seq_file *); |
04c567d9 | 23 | static void request_key_auth_revoke(struct key *); |
3e30148c | 24 | static void request_key_auth_destroy(struct key *); |
b5f545c8 | 25 | static long request_key_auth_read(const struct key *, char __user *, size_t); |
3e30148c DH |
26 | |
27 | /* | |
973c9f4f | 28 | * The request-key authorisation key type definition. |
3e30148c DH |
29 | */ |
30 | struct key_type key_type_request_key_auth = { | |
31 | .name = ".request_key_auth", | |
32 | .def_datalen = sizeof(struct request_key_auth), | |
f1dcde91 DH |
33 | .preparse = request_key_auth_preparse, |
34 | .free_preparse = request_key_auth_free_preparse, | |
3e30148c DH |
35 | .instantiate = request_key_auth_instantiate, |
36 | .describe = request_key_auth_describe, | |
04c567d9 | 37 | .revoke = request_key_auth_revoke, |
3e30148c | 38 | .destroy = request_key_auth_destroy, |
b5f545c8 | 39 | .read = request_key_auth_read, |
3e30148c DH |
40 | }; |
41 | ||
8da79b64 | 42 | static int request_key_auth_preparse(struct key_preparsed_payload *prep) |
f1dcde91 DH |
43 | { |
44 | return 0; | |
45 | } | |
46 | ||
8da79b64 | 47 | static void request_key_auth_free_preparse(struct key_preparsed_payload *prep) |
f1dcde91 DH |
48 | { |
49 | } | |
50 | ||
3e30148c | 51 | /* |
973c9f4f | 52 | * Instantiate a request-key authorisation key. |
3e30148c DH |
53 | */ |
54 | static int request_key_auth_instantiate(struct key *key, | |
cf7f601c | 55 | struct key_preparsed_payload *prep) |
3e30148c | 56 | { |
e59428f7 | 57 | rcu_assign_keypointer(key, (struct request_key_auth *)prep->data); |
b5f545c8 | 58 | return 0; |
a8b17ed0 | 59 | } |
3e30148c | 60 | |
3e30148c | 61 | /* |
973c9f4f | 62 | * Describe an authorisation token. |
3e30148c DH |
63 | */ |
64 | static void request_key_auth_describe(const struct key *key, | |
65 | struct seq_file *m) | |
66 | { | |
e59428f7 | 67 | struct request_key_auth *rka = dereference_key_rcu(key); |
3e30148c DH |
68 | |
69 | seq_puts(m, "key:"); | |
70 | seq_puts(m, key->description); | |
363b02da | 71 | if (key_is_positive(key)) |
78b7280c | 72 | seq_printf(m, " pid:%d ci:%zu", rka->pid, rka->callout_len); |
a8b17ed0 | 73 | } |
3e30148c | 74 | |
b5f545c8 | 75 | /* |
973c9f4f | 76 | * Read the callout_info data (retrieves the callout information). |
b5f545c8 DH |
77 | * - the key's semaphore is read-locked |
78 | */ | |
79 | static long request_key_auth_read(const struct key *key, | |
80 | char __user *buffer, size_t buflen) | |
81 | { | |
e59428f7 | 82 | struct request_key_auth *rka = dereference_key_locked(key); |
b5f545c8 DH |
83 | size_t datalen; |
84 | long ret; | |
85 | ||
4a38e122 | 86 | datalen = rka->callout_len; |
b5f545c8 DH |
87 | ret = datalen; |
88 | ||
89 | /* we can return the data as is */ | |
90 | if (buffer && buflen > 0) { | |
91 | if (buflen > datalen) | |
92 | buflen = datalen; | |
93 | ||
94 | if (copy_to_user(buffer, rka->callout_info, buflen) != 0) | |
95 | ret = -EFAULT; | |
96 | } | |
97 | ||
98 | return ret; | |
a8b17ed0 | 99 | } |
b5f545c8 | 100 | |
44d81433 EB |
101 | static void free_request_key_auth(struct request_key_auth *rka) |
102 | { | |
103 | if (!rka) | |
104 | return; | |
105 | key_put(rka->target_key); | |
106 | key_put(rka->dest_keyring); | |
107 | if (rka->cred) | |
108 | put_cred(rka->cred); | |
109 | kfree(rka->callout_info); | |
110 | kfree(rka); | |
111 | } | |
112 | ||
e59428f7 DH |
113 | /* |
114 | * Dispose of the request_key_auth record under RCU conditions | |
115 | */ | |
116 | static void request_key_auth_rcu_disposal(struct rcu_head *rcu) | |
117 | { | |
118 | struct request_key_auth *rka = | |
119 | container_of(rcu, struct request_key_auth, rcu); | |
120 | ||
121 | free_request_key_auth(rka); | |
122 | } | |
123 | ||
124 | /* | |
125 | * Handle revocation of an authorisation token key. | |
126 | * | |
127 | * Called with the key sem write-locked. | |
128 | */ | |
129 | static void request_key_auth_revoke(struct key *key) | |
130 | { | |
131 | struct request_key_auth *rka = dereference_key_locked(key); | |
132 | ||
133 | kenter("{%d}", key->serial); | |
134 | rcu_assign_keypointer(key, NULL); | |
135 | call_rcu(&rka->rcu, request_key_auth_rcu_disposal); | |
136 | } | |
137 | ||
3e30148c | 138 | /* |
973c9f4f | 139 | * Destroy an instantiation authorisation token key. |
3e30148c DH |
140 | */ |
141 | static void request_key_auth_destroy(struct key *key) | |
142 | { | |
e59428f7 | 143 | struct request_key_auth *rka = rcu_access_pointer(key->payload.rcu_data0); |
3e30148c DH |
144 | |
145 | kenter("{%d}", key->serial); | |
e59428f7 DH |
146 | if (rka) { |
147 | rcu_assign_keypointer(key, NULL); | |
148 | call_rcu(&rka->rcu, request_key_auth_rcu_disposal); | |
149 | } | |
a8b17ed0 | 150 | } |
3e30148c | 151 | |
3e30148c | 152 | /* |
973c9f4f DH |
153 | * Create an authorisation token for /sbin/request-key or whoever to gain |
154 | * access to the caller's security data. | |
3e30148c | 155 | */ |
822ad64d DH |
156 | struct key *request_key_auth_new(struct key *target, const char *op, |
157 | const void *callout_info, size_t callout_len, | |
158 | struct key *dest_keyring) | |
3e30148c | 159 | { |
b5f545c8 | 160 | struct request_key_auth *rka, *irka; |
7936d16d | 161 | const struct cred *cred = current_cred(); |
b5f545c8 | 162 | struct key *authkey = NULL; |
3e30148c | 163 | char desc[20]; |
44d81433 | 164 | int ret = -ENOMEM; |
3e30148c DH |
165 | |
166 | kenter("%d,", target->serial); | |
167 | ||
b5f545c8 | 168 | /* allocate a auth record */ |
44d81433 EB |
169 | rka = kzalloc(sizeof(*rka), GFP_KERNEL); |
170 | if (!rka) | |
171 | goto error; | |
e007ce9c | 172 | rka->callout_info = kmemdup(callout_info, callout_len, GFP_KERNEL); |
44d81433 EB |
173 | if (!rka->callout_info) |
174 | goto error_free_rka; | |
e007ce9c | 175 | rka->callout_len = callout_len; |
822ad64d | 176 | strlcpy(rka->op, op, sizeof(rka->op)); |
3e30148c | 177 | |
b5f545c8 DH |
178 | /* see if the calling process is already servicing the key request of |
179 | * another process */ | |
d84f4f99 | 180 | if (cred->request_key_auth) { |
b5f545c8 | 181 | /* it is - use that instantiation context here too */ |
d84f4f99 | 182 | down_read(&cred->request_key_auth->sem); |
04c567d9 DH |
183 | |
184 | /* if the auth key has been revoked, then the key we're | |
185 | * servicing is already instantiated */ | |
44d81433 EB |
186 | if (test_bit(KEY_FLAG_REVOKED, |
187 | &cred->request_key_auth->flags)) { | |
188 | up_read(&cred->request_key_auth->sem); | |
189 | ret = -EKEYREVOKED; | |
190 | goto error_free_rka; | |
191 | } | |
04c567d9 | 192 | |
146aa8b1 | 193 | irka = cred->request_key_auth->payload.data[0]; |
d84f4f99 | 194 | rka->cred = get_cred(irka->cred); |
b5f545c8 | 195 | rka->pid = irka->pid; |
04c567d9 | 196 | |
d84f4f99 | 197 | up_read(&cred->request_key_auth->sem); |
3e30148c | 198 | } |
b5f545c8 DH |
199 | else { |
200 | /* it isn't - use this process as the context */ | |
d84f4f99 | 201 | rka->cred = get_cred(cred); |
b5f545c8 DH |
202 | rka->pid = current->pid; |
203 | } | |
204 | ||
205 | rka->target_key = key_get(target); | |
8bbf4976 | 206 | rka->dest_keyring = key_get(dest_keyring); |
3e30148c DH |
207 | |
208 | /* allocate the auth key */ | |
209 | sprintf(desc, "%x", target->serial); | |
210 | ||
b5f545c8 | 211 | authkey = key_alloc(&key_type_request_key_auth, desc, |
d84f4f99 | 212 | cred->fsuid, cred->fsgid, cred, |
028db3e2 LT |
213 | KEY_POS_VIEW | KEY_POS_READ | KEY_POS_SEARCH | KEY_POS_LINK | |
214 | KEY_USR_VIEW, KEY_ALLOC_NOT_IN_QUOTA, NULL); | |
b5f545c8 DH |
215 | if (IS_ERR(authkey)) { |
216 | ret = PTR_ERR(authkey); | |
44d81433 | 217 | goto error_free_rka; |
3e30148c DH |
218 | } |
219 | ||
d84f4f99 | 220 | /* construct the auth key */ |
b5f545c8 DH |
221 | ret = key_instantiate_and_link(authkey, rka, 0, NULL, NULL); |
222 | if (ret < 0) | |
44d81433 | 223 | goto error_put_authkey; |
3e30148c | 224 | |
fff29291 | 225 | kleave(" = {%d,%d}", authkey->serial, refcount_read(&authkey->usage)); |
b5f545c8 DH |
226 | return authkey; |
227 | ||
44d81433 | 228 | error_put_authkey: |
b5f545c8 | 229 | key_put(authkey); |
44d81433 EB |
230 | error_free_rka: |
231 | free_request_key_auth(rka); | |
232 | error: | |
b5f545c8 DH |
233 | kleave("= %d", ret); |
234 | return ERR_PTR(ret); | |
a8b17ed0 | 235 | } |
3e30148c | 236 | |
3e30148c | 237 | /* |
973c9f4f DH |
238 | * Search the current process's keyrings for the authorisation key for |
239 | * instantiation of a key. | |
3e30148c DH |
240 | */ |
241 | struct key *key_get_instantiation_authkey(key_serial_t target_id) | |
242 | { | |
d0a059ca | 243 | char description[16]; |
4bdf0bc3 DH |
244 | struct keyring_search_context ctx = { |
245 | .index_key.type = &key_type_request_key_auth, | |
d0a059ca | 246 | .index_key.description = description, |
4bdf0bc3 | 247 | .cred = current_cred(), |
c06cfb08 | 248 | .match_data.cmp = key_default_cmp, |
46291959 DH |
249 | .match_data.raw_data = description, |
250 | .match_data.lookup_type = KEYRING_SEARCH_LOOKUP_DIRECT, | |
dcf49dbc DH |
251 | .flags = (KEYRING_SEARCH_DO_STATE_CHECK | |
252 | KEYRING_SEARCH_RECURSE), | |
4bdf0bc3 | 253 | }; |
b5f545c8 DH |
254 | struct key *authkey; |
255 | key_ref_t authkey_ref; | |
256 | ||
ede0fa98 | 257 | ctx.index_key.desc_len = sprintf(description, "%x", target_id); |
d0a059ca | 258 | |
e59428f7 DH |
259 | rcu_read_lock(); |
260 | authkey_ref = search_process_keyrings_rcu(&ctx); | |
261 | rcu_read_unlock(); | |
b5f545c8 DH |
262 | |
263 | if (IS_ERR(authkey_ref)) { | |
e231c2ee | 264 | authkey = ERR_CAST(authkey_ref); |
4d67431f DH |
265 | if (authkey == ERR_PTR(-EAGAIN)) |
266 | authkey = ERR_PTR(-ENOKEY); | |
b5f545c8 DH |
267 | goto error; |
268 | } | |
3e30148c | 269 | |
b5f545c8 DH |
270 | authkey = key_ref_to_ptr(authkey_ref); |
271 | if (test_bit(KEY_FLAG_REVOKED, &authkey->flags)) { | |
272 | key_put(authkey); | |
273 | authkey = ERR_PTR(-EKEYREVOKED); | |
274 | } | |
3e30148c | 275 | |
b5f545c8 DH |
276 | error: |
277 | return authkey; | |
a8b17ed0 | 278 | } |