1/* user_defined.c: user defined key type
2 *
3 * Copyright (C) 2004 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
12#include <linux/module.h>
13#include <linux/init.h>
14#include <linux/slab.h>
15#include <linux/seq_file.h>
16#include <linux/err.h>
17#include <keys/user-type.h>
18#include <asm/uaccess.h>
19#include "internal.h"
20
21static int logon_vet_description(const char *desc);
22
23/*
24 * user defined keys take an arbitrary string as the description and an
25 * arbitrary blob of data as the payload
26 */
27struct key_type key_type_user = {
28	.name			= "user",
29	.preparse		= user_preparse,
30	.free_preparse		= user_free_preparse,
31	.instantiate		= generic_key_instantiate,
32	.update			= user_update,
33	.revoke			= user_revoke,
34	.destroy		= user_destroy,
35	.describe		= user_describe,
36	.read			= user_read,
37};
38
39EXPORT_SYMBOL_GPL(key_type_user);
40
41/*
42 * This key type is essentially the same as key_type_user, but it does
43 * not define a .read op. This is suitable for storing username and
44 * password pairs in the keyring that you do not want to be readable
45 * from userspace.
46 */
47struct key_type key_type_logon = {
48	.name			= "logon",
49	.preparse		= user_preparse,
50	.free_preparse		= user_free_preparse,
51	.instantiate		= generic_key_instantiate,
52	.update			= user_update,
53	.revoke			= user_revoke,
54	.destroy		= user_destroy,
55	.describe		= user_describe,
56	.vet_description	= logon_vet_description,
57};
58EXPORT_SYMBOL_GPL(key_type_logon);
59
60/*
61 * Preparse a user defined key payload
62 */
63int user_preparse(struct key_preparsed_payload *prep)
64{
65	struct user_key_payload *upayload;
66	size_t datalen = prep->datalen;
67
68	if (datalen <= 0 || datalen > 32767 || !prep->data)
69		return -EINVAL;
70
71	upayload = kmalloc(sizeof(*upayload) + datalen, GFP_KERNEL);
72	if (!upayload)
73		return -ENOMEM;
74
75	/* attach the data */
76	prep->quotalen = datalen;
77	prep->payload[0] = upayload;
78	upayload->datalen = datalen;
79	memcpy(upayload->data, prep->data, datalen);
80	return 0;
81}
82EXPORT_SYMBOL_GPL(user_preparse);
83
84/*
85 * Free a preparse of a user defined key payload
86 */
87void user_free_preparse(struct key_preparsed_payload *prep)
88{
89	kfree(prep->payload[0]);
90}
91EXPORT_SYMBOL_GPL(user_free_preparse);
92
93/*
94 * update a user defined key
95 * - the key's semaphore is write-locked
96 */
97int user_update(struct key *key, struct key_preparsed_payload *prep)
98{
99	struct user_key_payload *upayload, *zap;
100	size_t datalen = prep->datalen;
101	int ret;
102
103	ret = -EINVAL;
104	if (datalen <= 0 || datalen > 32767 || !prep->data)
105		goto error;
106
107	/* construct a replacement payload */
108	ret = -ENOMEM;
109	upayload = kmalloc(sizeof(*upayload) + datalen, GFP_KERNEL);
110	if (!upayload)
111		goto error;
112
113	upayload->datalen = datalen;
114	memcpy(upayload->data, prep->data, datalen);
115
116	/* check the quota and attach the new data */
117	zap = upayload;
118
119	ret = key_payload_reserve(key, datalen);
120
121	if (ret == 0) {
122		/* attach the new data, displacing the old */
123		if (!test_bit(KEY_FLAG_NEGATIVE, &key->flags))
124			zap = key->payload.data;
125		else
126			zap = NULL;
127		rcu_assign_keypointer(key, upayload);
128		key->expiry = 0;
129	}
130
131	if (zap)
132		kfree_rcu(zap, rcu);
133
134error:
135	return ret;
136}
137
138EXPORT_SYMBOL_GPL(user_update);
139
140/*
141 * dispose of the links from a revoked keyring
142 * - called with the key sem write-locked
143 */
144void user_revoke(struct key *key)
145{
146	struct user_key_payload *upayload = key->payload.data;
147
148	/* clear the quota */
149	key_payload_reserve(key, 0);
150
151	if (upayload) {
152		rcu_assign_keypointer(key, NULL);
153		kfree_rcu(upayload, rcu);
154	}
155}
156
157EXPORT_SYMBOL(user_revoke);
158
159/*
160 * dispose of the data dangling from the corpse of a user key
161 */
162void user_destroy(struct key *key)
163{
164	struct user_key_payload *upayload = key->payload.data;
165
166	kfree(upayload);
167}
168
169EXPORT_SYMBOL_GPL(user_destroy);
170
171/*
172 * describe the user key
173 */
174void user_describe(const struct key *key, struct seq_file *m)
175{
176	seq_puts(m, key->description);
177	if (key_is_instantiated(key))
178		seq_printf(m, ": %u", key->datalen);
179}
180
181EXPORT_SYMBOL_GPL(user_describe);
182
183/*
184 * read the key data
185 * - the key's semaphore is read-locked
186 */
187long user_read(const struct key *key, char __user *buffer, size_t buflen)
188{
189	struct user_key_payload *upayload;
190	long ret;
191
192	upayload = rcu_dereference_key(key);
193	ret = upayload->datalen;
194
195	/* we can return the data as is */
196	if (buffer && buflen > 0) {
197		if (buflen > upayload->datalen)
198			buflen = upayload->datalen;
199
200		if (copy_to_user(buffer, upayload->data, buflen) != 0)
201			ret = -EFAULT;
202	}
203
204	return ret;
205}
206
207EXPORT_SYMBOL_GPL(user_read);
208
209/* Vet the description for a "logon" key */
210static int logon_vet_description(const char *desc)
211{
212	char *p;
213
214	/* require a "qualified" description string */
215	p = strchr(desc, ':');
216	if (!p)
217		return -EINVAL;
218
219	/* also reject description with ':' as first char */
220	if (p == desc)
221		return -EINVAL;
222
223	return 0;
224}
225