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1// SPDX-License-Identifier: GPL-2.0-or-later
2/* Request key authorisation token key definition.
3 *
4 * Copyright (C) 2005 Red Hat, Inc. All Rights Reserved.
5 * Written by David Howells (dhowells@redhat.com)
6 *
7 * See Documentation/security/keys/request-key.rst
8 */
9
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>
15#include "internal.h"
16#include <keys/request_key_auth-type.h>
17
18static int request_key_auth_preparse(struct key_preparsed_payload *);
19static void request_key_auth_free_preparse(struct key_preparsed_payload *);
20static int request_key_auth_instantiate(struct key *,
21 struct key_preparsed_payload *);
22static void request_key_auth_describe(const struct key *, struct seq_file *);
23static void request_key_auth_revoke(struct key *);
24static void request_key_auth_destroy(struct key *);
25static long request_key_auth_read(const struct key *, char __user *, size_t);
26
27/*
28 * The request-key authorisation key type definition.
29 */
30struct 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,
40};
41
42static int request_key_auth_preparse(struct key_preparsed_payload *prep)
43{
44 return 0;
45}
46
47static void request_key_auth_free_preparse(struct key_preparsed_payload *prep)
48{
49}
50
51/*
52 * Instantiate a request-key authorisation key.
53 */
54static int request_key_auth_instantiate(struct key *key,
55 struct key_preparsed_payload *prep)
56{
57 rcu_assign_keypointer(key, (struct request_key_auth *)prep->data);
58 return 0;
59}
60
61/*
62 * Describe an authorisation token.
63 */
64static void request_key_auth_describe(const struct key *key,
65 struct seq_file *m)
66{
67 struct request_key_auth *rka = dereference_key_rcu(key);
68
69 if (!rka)
70 return;
71
72 seq_puts(m, "key:");
73 seq_puts(m, key->description);
74 if (key_is_positive(key))
75 seq_printf(m, " pid:%d ci:%zu", rka->pid, rka->callout_len);
76}
77
78/*
79 * Read the callout_info data (retrieves the callout information).
80 * - the key's semaphore is read-locked
81 */
82static long request_key_auth_read(const struct key *key,
83 char __user *buffer, size_t buflen)
84{
85 struct request_key_auth *rka = dereference_key_locked(key);
86 size_t datalen;
87 long ret;
88
89 if (!rka)
90 return -EKEYREVOKED;
91
92 datalen = rka->callout_len;
93 ret = datalen;
94
95 /* we can return the data as is */
96 if (buffer && buflen > 0) {
97 if (buflen > datalen)
98 buflen = datalen;
99
100 if (copy_to_user(buffer, rka->callout_info, buflen) != 0)
101 ret = -EFAULT;
102 }
103
104 return ret;
105}
106
107static void free_request_key_auth(struct request_key_auth *rka)
108{
109 if (!rka)
110 return;
111 key_put(rka->target_key);
112 key_put(rka->dest_keyring);
113 if (rka->cred)
114 put_cred(rka->cred);
115 kfree(rka->callout_info);
116 kfree(rka);
117}
118
119/*
120 * Dispose of the request_key_auth record under RCU conditions
121 */
122static void request_key_auth_rcu_disposal(struct rcu_head *rcu)
123{
124 struct request_key_auth *rka =
125 container_of(rcu, struct request_key_auth, rcu);
126
127 free_request_key_auth(rka);
128}
129
130/*
131 * Handle revocation of an authorisation token key.
132 *
133 * Called with the key sem write-locked.
134 */
135static void request_key_auth_revoke(struct key *key)
136{
137 struct request_key_auth *rka = dereference_key_locked(key);
138
139 kenter("{%d}", key->serial);
140 rcu_assign_keypointer(key, NULL);
141 call_rcu(&rka->rcu, request_key_auth_rcu_disposal);
142}
143
144/*
145 * Destroy an instantiation authorisation token key.
146 */
147static void request_key_auth_destroy(struct key *key)
148{
149 struct request_key_auth *rka = rcu_access_pointer(key->payload.rcu_data0);
150
151 kenter("{%d}", key->serial);
152 if (rka) {
153 rcu_assign_keypointer(key, NULL);
154 call_rcu(&rka->rcu, request_key_auth_rcu_disposal);
155 }
156}
157
158/*
159 * Create an authorisation token for /sbin/request-key or whoever to gain
160 * access to the caller's security data.
161 */
162struct key *request_key_auth_new(struct key *target, const char *op,
163 const void *callout_info, size_t callout_len,
164 struct key *dest_keyring)
165{
166 struct request_key_auth *rka, *irka;
167 const struct cred *cred = current_cred();
168 struct key *authkey = NULL;
169 char desc[20];
170 int ret = -ENOMEM;
171
172 kenter("%d,", target->serial);
173
174 /* allocate a auth record */
175 rka = kzalloc(sizeof(*rka), GFP_KERNEL);
176 if (!rka)
177 goto error;
178 rka->callout_info = kmemdup(callout_info, callout_len, GFP_KERNEL);
179 if (!rka->callout_info)
180 goto error_free_rka;
181 rka->callout_len = callout_len;
182 strlcpy(rka->op, op, sizeof(rka->op));
183
184 /* see if the calling process is already servicing the key request of
185 * another process */
186 if (cred->request_key_auth) {
187 /* it is - use that instantiation context here too */
188 down_read(&cred->request_key_auth->sem);
189
190 /* if the auth key has been revoked, then the key we're
191 * servicing is already instantiated */
192 if (test_bit(KEY_FLAG_REVOKED,
193 &cred->request_key_auth->flags)) {
194 up_read(&cred->request_key_auth->sem);
195 ret = -EKEYREVOKED;
196 goto error_free_rka;
197 }
198
199 irka = cred->request_key_auth->payload.data[0];
200 rka->cred = get_cred(irka->cred);
201 rka->pid = irka->pid;
202
203 up_read(&cred->request_key_auth->sem);
204 }
205 else {
206 /* it isn't - use this process as the context */
207 rka->cred = get_cred(cred);
208 rka->pid = current->pid;
209 }
210
211 rka->target_key = key_get(target);
212 rka->dest_keyring = key_get(dest_keyring);
213
214 /* allocate the auth key */
215 sprintf(desc, "%x", target->serial);
216
217 authkey = key_alloc(&key_type_request_key_auth, desc,
218 cred->fsuid, cred->fsgid, cred,
219 KEY_POS_VIEW | KEY_POS_READ | KEY_POS_SEARCH | KEY_POS_LINK |
220 KEY_USR_VIEW, KEY_ALLOC_NOT_IN_QUOTA, NULL);
221 if (IS_ERR(authkey)) {
222 ret = PTR_ERR(authkey);
223 goto error_free_rka;
224 }
225
226 /* construct the auth key */
227 ret = key_instantiate_and_link(authkey, rka, 0, NULL, NULL);
228 if (ret < 0)
229 goto error_put_authkey;
230
231 kleave(" = {%d,%d}", authkey->serial, refcount_read(&authkey->usage));
232 return authkey;
233
234error_put_authkey:
235 key_put(authkey);
236error_free_rka:
237 free_request_key_auth(rka);
238error:
239 kleave("= %d", ret);
240 return ERR_PTR(ret);
241}
242
243/*
244 * Search the current process's keyrings for the authorisation key for
245 * instantiation of a key.
246 */
247struct key *key_get_instantiation_authkey(key_serial_t target_id)
248{
249 char description[16];
250 struct keyring_search_context ctx = {
251 .index_key.type = &key_type_request_key_auth,
252 .index_key.description = description,
253 .cred = current_cred(),
254 .match_data.cmp = key_default_cmp,
255 .match_data.raw_data = description,
256 .match_data.lookup_type = KEYRING_SEARCH_LOOKUP_DIRECT,
257 .flags = (KEYRING_SEARCH_DO_STATE_CHECK |
258 KEYRING_SEARCH_RECURSE),
259 };
260 struct key *authkey;
261 key_ref_t authkey_ref;
262
263 ctx.index_key.desc_len = sprintf(description, "%x", target_id);
264
265 rcu_read_lock();
266 authkey_ref = search_process_keyrings_rcu(&ctx);
267 rcu_read_unlock();
268
269 if (IS_ERR(authkey_ref)) {
270 authkey = ERR_CAST(authkey_ref);
271 if (authkey == ERR_PTR(-EAGAIN))
272 authkey = ERR_PTR(-ENOKEY);
273 goto error;
274 }
275
276 authkey = key_ref_to_ptr(authkey_ref);
277 if (test_bit(KEY_FLAG_REVOKED, &authkey->flags)) {
278 key_put(authkey);
279 authkey = ERR_PTR(-EKEYREVOKED);
280 }
281
282error:
283 return authkey;
284}
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.txt
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 <asm/uaccess.h>
20#include "internal.h"
21
22static int request_key_auth_instantiate(struct key *, const void *, size_t);
23static void request_key_auth_describe(const struct key *, struct seq_file *);
24static void request_key_auth_revoke(struct key *);
25static void request_key_auth_destroy(struct key *);
26static long request_key_auth_read(const struct key *, char __user *, size_t);
27
28/*
29 * The request-key authorisation key type definition.
30 */
31struct 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,
39};
40
41/*
42 * Instantiate a request-key authorisation key.
43 */
44static int request_key_auth_instantiate(struct key *key,
45 const void *data,
46 size_t datalen)
47{
48 key->payload.data = (struct request_key_auth *) data;
49 return 0;
50}
51
52/*
53 * Describe an authorisation token.
54 */
55static 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);
62 if (key_is_instantiated(key))
63 seq_printf(m, " pid:%d ci:%zu", rka->pid, rka->callout_len);
64}
65
66/*
67 * Read the callout_info data (retrieves the callout information).
68 * - the key's semaphore is read-locked
69 */
70static long request_key_auth_read(const struct key *key,
71 char __user *buffer, size_t buflen)
72{
73 struct request_key_auth *rka = key->payload.data;
74 size_t datalen;
75 long ret;
76
77 datalen = rka->callout_len;
78 ret = datalen;
79
80 /* we can return the data as is */
81 if (buffer && buflen > 0) {
82 if (buflen > datalen)
83 buflen = datalen;
84
85 if (copy_to_user(buffer, rka->callout_info, buflen) != 0)
86 ret = -EFAULT;
87 }
88
89 return ret;
90}
91
92/*
93 * Handle revocation of an authorisation token key.
94 *
95 * Called with the key sem write-locked.
96 */
97static void request_key_auth_revoke(struct key *key)
98{
99 struct request_key_auth *rka = key->payload.data;
100
101 kenter("{%d}", key->serial);
102
103 if (rka->cred) {
104 put_cred(rka->cred);
105 rka->cred = NULL;
106 }
107}
108
109/*
110 * Destroy an instantiation authorisation token key.
111 */
112static void request_key_auth_destroy(struct key *key)
113{
114 struct request_key_auth *rka = key->payload.data;
115
116 kenter("{%d}", key->serial);
117
118 if (rka->cred) {
119 put_cred(rka->cred);
120 rka->cred = NULL;
121 }
122
123 key_put(rka->target_key);
124 key_put(rka->dest_keyring);
125 kfree(rka->callout_info);
126 kfree(rka);
127}
128
129/*
130 * Create an authorisation token for /sbin/request-key or whoever to gain
131 * access to the caller's security data.
132 */
133struct key *request_key_auth_new(struct key *target, const void *callout_info,
134 size_t callout_len, struct key *dest_keyring)
135{
136 struct request_key_auth *rka, *irka;
137 const struct cred *cred = current->cred;
138 struct key *authkey = NULL;
139 char desc[20];
140 int ret;
141
142 kenter("%d,", target->serial);
143
144 /* allocate a auth record */
145 rka = kmalloc(sizeof(*rka), GFP_KERNEL);
146 if (!rka) {
147 kleave(" = -ENOMEM");
148 return ERR_PTR(-ENOMEM);
149 }
150 rka->callout_info = kmalloc(callout_len, GFP_KERNEL);
151 if (!rka->callout_info) {
152 kleave(" = -ENOMEM");
153 kfree(rka);
154 return ERR_PTR(-ENOMEM);
155 }
156
157 /* see if the calling process is already servicing the key request of
158 * another process */
159 if (cred->request_key_auth) {
160 /* it is - use that instantiation context here too */
161 down_read(&cred->request_key_auth->sem);
162
163 /* if the auth key has been revoked, then the key we're
164 * servicing is already instantiated */
165 if (test_bit(KEY_FLAG_REVOKED, &cred->request_key_auth->flags))
166 goto auth_key_revoked;
167
168 irka = cred->request_key_auth->payload.data;
169 rka->cred = get_cred(irka->cred);
170 rka->pid = irka->pid;
171
172 up_read(&cred->request_key_auth->sem);
173 }
174 else {
175 /* it isn't - use this process as the context */
176 rka->cred = get_cred(cred);
177 rka->pid = current->pid;
178 }
179
180 rka->target_key = key_get(target);
181 rka->dest_keyring = key_get(dest_keyring);
182 memcpy(rka->callout_info, callout_info, callout_len);
183 rka->callout_len = callout_len;
184
185 /* allocate the auth key */
186 sprintf(desc, "%x", target->serial);
187
188 authkey = key_alloc(&key_type_request_key_auth, desc,
189 cred->fsuid, cred->fsgid, cred,
190 KEY_POS_VIEW | KEY_POS_READ | KEY_POS_SEARCH |
191 KEY_USR_VIEW, KEY_ALLOC_NOT_IN_QUOTA);
192 if (IS_ERR(authkey)) {
193 ret = PTR_ERR(authkey);
194 goto error_alloc;
195 }
196
197 /* construct the auth key */
198 ret = key_instantiate_and_link(authkey, rka, 0, NULL, NULL);
199 if (ret < 0)
200 goto error_inst;
201
202 kleave(" = {%d,%d}", authkey->serial, atomic_read(&authkey->usage));
203 return authkey;
204
205auth_key_revoked:
206 up_read(&cred->request_key_auth->sem);
207 kfree(rka->callout_info);
208 kfree(rka);
209 kleave("= -EKEYREVOKED");
210 return ERR_PTR(-EKEYREVOKED);
211
212error_inst:
213 key_revoke(authkey);
214 key_put(authkey);
215error_alloc:
216 key_put(rka->target_key);
217 key_put(rka->dest_keyring);
218 kfree(rka->callout_info);
219 kfree(rka);
220 kleave("= %d", ret);
221 return ERR_PTR(ret);
222}
223
224/*
225 * See if an authorisation key is associated with a particular key.
226 */
227static int key_get_instantiation_authkey_match(const struct key *key,
228 const void *_id)
229{
230 struct request_key_auth *rka = key->payload.data;
231 key_serial_t id = (key_serial_t)(unsigned long) _id;
232
233 return rka->target_key->serial == id;
234}
235
236/*
237 * Search the current process's keyrings for the authorisation key for
238 * instantiation of a key.
239 */
240struct key *key_get_instantiation_authkey(key_serial_t target_id)
241{
242 const struct cred *cred = current_cred();
243 struct key *authkey;
244 key_ref_t authkey_ref;
245
246 authkey_ref = search_process_keyrings(
247 &key_type_request_key_auth,
248 (void *) (unsigned long) target_id,
249 key_get_instantiation_authkey_match,
250 cred);
251
252 if (IS_ERR(authkey_ref)) {
253 authkey = ERR_CAST(authkey_ref);
254 if (authkey == ERR_PTR(-EAGAIN))
255 authkey = ERR_PTR(-ENOKEY);
256 goto error;
257 }
258
259 authkey = key_ref_to_ptr(authkey_ref);
260 if (test_bit(KEY_FLAG_REVOKED, &authkey->flags)) {
261 key_put(authkey);
262 authkey = ERR_PTR(-EKEYREVOKED);
263 }
264
265error:
266 return authkey;
267}