1// SPDX-License-Identifier: GPL-2.0-or-later
2/* user_defined.c: user defined key type
3 *
4 * Copyright (C) 2004 Red Hat, Inc. All Rights Reserved.
5 * Written by David Howells (dhowells@redhat.com)
6 */
7
8#include <linux/export.h>
9#include <linux/init.h>
10#include <linux/slab.h>
11#include <linux/seq_file.h>
12#include <linux/err.h>
13#include <keys/user-type.h>
14#include <linux/uaccess.h>
15#include "internal.h"
16
17static int logon_vet_description(const char *desc);
18
19/*
20 * user defined keys take an arbitrary string as the description and an
21 * arbitrary blob of data as the payload
22 */
23struct key_type key_type_user = {
24 .name = "user",
25 .preparse = user_preparse,
26 .free_preparse = user_free_preparse,
27 .instantiate = generic_key_instantiate,
28 .update = user_update,
29 .revoke = user_revoke,
30 .destroy = user_destroy,
31 .describe = user_describe,
32 .read = user_read,
33};
34
35EXPORT_SYMBOL_GPL(key_type_user);
36
37/*
38 * This key type is essentially the same as key_type_user, but it does
39 * not define a .read op. This is suitable for storing username and
40 * password pairs in the keyring that you do not want to be readable
41 * from userspace.
42 */
43struct key_type key_type_logon = {
44 .name = "logon",
45 .preparse = user_preparse,
46 .free_preparse = user_free_preparse,
47 .instantiate = generic_key_instantiate,
48 .update = user_update,
49 .revoke = user_revoke,
50 .destroy = user_destroy,
51 .describe = user_describe,
52 .vet_description = logon_vet_description,
53};
54EXPORT_SYMBOL_GPL(key_type_logon);
55
56/*
57 * Preparse a user defined key payload
58 */
59int user_preparse(struct key_preparsed_payload *prep)
60{
61 struct user_key_payload *upayload;
62 size_t datalen = prep->datalen;
63
64 if (datalen <= 0 || datalen > 32767 || !prep->data)
65 return -EINVAL;
66
67 upayload = kmalloc(sizeof(*upayload) + datalen, GFP_KERNEL);
68 if (!upayload)
69 return -ENOMEM;
70
71 /* attach the data */
72 prep->quotalen = datalen;
73 prep->payload.data[0] = upayload;
74 upayload->datalen = datalen;
75 memcpy(to: upayload->data, from: prep->data, len: datalen);
76 return 0;
77}
78EXPORT_SYMBOL_GPL(user_preparse);
79
80/*
81 * Free a preparse of a user defined key payload
82 */
83void user_free_preparse(struct key_preparsed_payload *prep)
84{
85 kfree_sensitive(objp: prep->payload.data[0]);
86}
87EXPORT_SYMBOL_GPL(user_free_preparse);
88
89static void user_free_payload_rcu(struct rcu_head *head)
90{
91 struct user_key_payload *payload;
92
93 payload = container_of(head, struct user_key_payload, rcu);
94 kfree_sensitive(objp: payload);
95}
96
97/*
98 * update a user defined key
99 * - the key's semaphore is write-locked
100 */
101int user_update(struct key *key, struct key_preparsed_payload *prep)
102{
103 struct user_key_payload *zap = NULL;
104 int ret;
105
106 /* check the quota and attach the new data */
107 ret = key_payload_reserve(key, datalen: prep->datalen);
108 if (ret < 0)
109 return ret;
110
111 /* attach the new data, displacing the old */
112 key->expiry = prep->expiry;
113 if (key_is_positive(key))
114 zap = dereference_key_locked(key);
115 rcu_assign_keypointer(key, prep->payload.data[0]);
116 prep->payload.data[0] = NULL;
117
118 if (zap)
119 call_rcu(head: &zap->rcu, func: user_free_payload_rcu);
120 return ret;
121}
122EXPORT_SYMBOL_GPL(user_update);
123
124/*
125 * dispose of the links from a revoked keyring
126 * - called with the key sem write-locked
127 */
128void user_revoke(struct key *key)
129{
130 struct user_key_payload *upayload = user_key_payload_locked(key);
131
132 /* clear the quota */
133 key_payload_reserve(key, datalen: 0);
134
135 if (upayload) {
136 rcu_assign_keypointer(key, NULL);
137 call_rcu(head: &upayload->rcu, func: user_free_payload_rcu);
138 }
139}
140
141EXPORT_SYMBOL(user_revoke);
142
143/*
144 * dispose of the data dangling from the corpse of a user key
145 */
146void user_destroy(struct key *key)
147{
148 struct user_key_payload *upayload = key->payload.data[0];
149
150 kfree_sensitive(objp: upayload);
151}
152
153EXPORT_SYMBOL_GPL(user_destroy);
154
155/*
156 * describe the user key
157 */
158void user_describe(const struct key *key, struct seq_file *m)
159{
160 seq_puts(m, s: key->description);
161 if (key_is_positive(key))
162 seq_printf(m, fmt: ": %u", key->datalen);
163}
164
165EXPORT_SYMBOL_GPL(user_describe);
166
167/*
168 * read the key data
169 * - the key's semaphore is read-locked
170 */
171long user_read(const struct key *key, char *buffer, size_t buflen)
172{
173 const struct user_key_payload *upayload;
174 long ret;
175
176 upayload = user_key_payload_locked(key);
177 ret = upayload->datalen;
178
179 /* we can return the data as is */
180 if (buffer && buflen > 0) {
181 if (buflen > upayload->datalen)
182 buflen = upayload->datalen;
183
184 memcpy(to: buffer, from: upayload->data, len: buflen);
185 }
186
187 return ret;
188}
189
190EXPORT_SYMBOL_GPL(user_read);
191
192/* Vet the description for a "logon" key */
193static int logon_vet_description(const char *desc)
194{
195 char *p;
196
197 /* require a "qualified" description string */
198 p = strchr(desc, ':');
199 if (!p)
200 return -EINVAL;
201
202 /* also reject description with ':' as first char */
203 if (p == desc)
204 return -EINVAL;
205
206 return 0;
207}
208