xref: /kernel/linux/linux-5.10/certs/blacklist.c (revision 8c2ecf20) 
1// SPDX-License-Identifier: GPL-2.0-or-later
2/* System hash blacklist.
3 *
4 * Copyright (C) 2016 Red Hat, Inc. All Rights Reserved.
5 * Written by David Howells (dhowells@redhat.com)
6 */
7
8#define pr_fmt(fmt) "blacklist: "fmt
9#include <linux/module.h>
10#include <linux/slab.h>
11#include <linux/key.h>
12#include <linux/key-type.h>
13#include <linux/sched.h>
14#include <linux/ctype.h>
15#include <linux/err.h>
16#include <linux/seq_file.h>
17#include <keys/system_keyring.h>
18#include "blacklist.h"
19#include "common.h"
20
21static struct key *blacklist_keyring;
22
23#ifdef CONFIG_SYSTEM_REVOCATION_LIST
24extern __initconst const u8 revocation_certificate_list[];
25extern __initconst const unsigned long revocation_certificate_list_size;
26#endif
27
28/*
29 * The description must be a type prefix, a colon and then an even number of
30 * hex digits.  The hash is kept in the description.
31 */
32static int blacklist_vet_description(const char *desc)
33{
34	int n = 0;
35
36	if (*desc == ':')
37		return -EINVAL;
38	for (; *desc; desc++)
39		if (*desc == ':')
40			goto found_colon;
41	return -EINVAL;
42
43found_colon:
44	desc++;
45	for (; *desc; desc++) {
46		if (!isxdigit(*desc))
47			return -EINVAL;
48		n++;
49	}
50
51	if (n == 0 || n & 1)
52		return -EINVAL;
53	return 0;
54}
55
56/*
57 * The hash to be blacklisted is expected to be in the description.  There will
58 * be no payload.
59 */
60static int blacklist_preparse(struct key_preparsed_payload *prep)
61{
62	if (prep->datalen > 0)
63		return -EINVAL;
64	return 0;
65}
66
67static void blacklist_free_preparse(struct key_preparsed_payload *prep)
68{
69}
70
71static void blacklist_describe(const struct key *key, struct seq_file *m)
72{
73	seq_puts(m, key->description);
74}
75
76static struct key_type key_type_blacklist = {
77	.name			= "blacklist",
78	.vet_description	= blacklist_vet_description,
79	.preparse		= blacklist_preparse,
80	.free_preparse		= blacklist_free_preparse,
81	.instantiate		= generic_key_instantiate,
82	.describe		= blacklist_describe,
83};
84
85/**
86 * mark_hash_blacklisted - Add a hash to the system blacklist
87 * @hash - The hash as a hex string with a type prefix (eg. "tbs:23aa429783")
88 */
89int mark_hash_blacklisted(const char *hash)
90{
91	key_ref_t key;
92
93	key = key_create_or_update(make_key_ref(blacklist_keyring, true),
94				   "blacklist",
95				   hash,
96				   NULL,
97				   0,
98				   ((KEY_POS_ALL & ~KEY_POS_SETATTR) |
99				    KEY_USR_VIEW),
100				   KEY_ALLOC_NOT_IN_QUOTA |
101				   KEY_ALLOC_BUILT_IN);
102	if (IS_ERR(key)) {
103		pr_err("Problem blacklisting hash (%ld)\n", PTR_ERR(key));
104		return PTR_ERR(key);
105	}
106	return 0;
107}
108
109/**
110 * is_hash_blacklisted - Determine if a hash is blacklisted
111 * @hash: The hash to be checked as a binary blob
112 * @hash_len: The length of the binary hash
113 * @type: Type of hash
114 */
115int is_hash_blacklisted(const u8 *hash, size_t hash_len, const char *type)
116{
117	key_ref_t kref;
118	size_t type_len = strlen(type);
119	char *buffer, *p;
120	int ret = 0;
121
122	buffer = kmalloc(type_len + 1 + hash_len * 2 + 1, GFP_KERNEL);
123	if (!buffer)
124		return -ENOMEM;
125	p = memcpy(buffer, type, type_len);
126	p += type_len;
127	*p++ = ':';
128	bin2hex(p, hash, hash_len);
129	p += hash_len * 2;
130	*p = 0;
131
132	kref = keyring_search(make_key_ref(blacklist_keyring, true),
133			      &key_type_blacklist, buffer, false);
134	if (!IS_ERR(kref)) {
135		key_ref_put(kref);
136		ret = -EKEYREJECTED;
137	}
138
139	kfree(buffer);
140	return ret;
141}
142EXPORT_SYMBOL_GPL(is_hash_blacklisted);
143
144int is_binary_blacklisted(const u8 *hash, size_t hash_len)
145{
146	if (is_hash_blacklisted(hash, hash_len, "bin") == -EKEYREJECTED)
147		return -EPERM;
148
149	return 0;
150}
151EXPORT_SYMBOL_GPL(is_binary_blacklisted);
152
153#ifdef CONFIG_SYSTEM_REVOCATION_LIST
154/**
155 * add_key_to_revocation_list - Add a revocation certificate to the blacklist
156 * @data: The data blob containing the certificate
157 * @size: The size of data blob
158 */
159int add_key_to_revocation_list(const char *data, size_t size)
160{
161	key_ref_t key;
162
163	key = key_create_or_update(make_key_ref(blacklist_keyring, true),
164				   "asymmetric",
165				   NULL,
166				   data,
167				   size,
168				   ((KEY_POS_ALL & ~KEY_POS_SETATTR) | KEY_USR_VIEW),
169				   KEY_ALLOC_NOT_IN_QUOTA | KEY_ALLOC_BUILT_IN);
170
171	if (IS_ERR(key)) {
172		pr_err("Problem with revocation key (%ld)\n", PTR_ERR(key));
173		return PTR_ERR(key);
174	}
175
176	return 0;
177}
178
179/**
180 * is_key_on_revocation_list - Determine if the key for a PKCS#7 message is revoked
181 * @pkcs7: The PKCS#7 message to check
182 */
183int is_key_on_revocation_list(struct pkcs7_message *pkcs7)
184{
185	int ret;
186
187	ret = pkcs7_validate_trust(pkcs7, blacklist_keyring);
188
189	if (ret == 0)
190		return -EKEYREJECTED;
191
192	return -ENOKEY;
193}
194#endif
195
196/*
197 * Initialise the blacklist
198 */
199static int __init blacklist_init(void)
200{
201	const char *const *bl;
202
203	if (register_key_type(&key_type_blacklist) < 0)
204		panic("Can't allocate system blacklist key type\n");
205
206	blacklist_keyring =
207		keyring_alloc(".blacklist",
208			      KUIDT_INIT(0), KGIDT_INIT(0),
209			      current_cred(),
210			      (KEY_POS_ALL & ~KEY_POS_SETATTR) |
211			      KEY_USR_VIEW | KEY_USR_READ |
212			      KEY_USR_SEARCH,
213			      KEY_ALLOC_NOT_IN_QUOTA |
214			      KEY_ALLOC_SET_KEEP,
215			      NULL, NULL);
216	if (IS_ERR(blacklist_keyring))
217		panic("Can't allocate system blacklist keyring\n");
218
219	for (bl = blacklist_hashes; *bl; bl++)
220		if (mark_hash_blacklisted(*bl) < 0)
221			pr_err("- blacklisting failed\n");
222	return 0;
223}
224
225/*
226 * Must be initialised before we try and load the keys into the keyring.
227 */
228device_initcall(blacklist_init);
229
230#ifdef CONFIG_SYSTEM_REVOCATION_LIST
231/*
232 * Load the compiled-in list of revocation X.509 certificates.
233 */
234static __init int load_revocation_certificate_list(void)
235{
236	if (revocation_certificate_list_size)
237		pr_notice("Loading compiled-in revocation X.509 certificates\n");
238
239	return load_certificate_list(revocation_certificate_list, revocation_certificate_list_size,
240				     blacklist_keyring);
241}
242late_initcall(load_revocation_certificate_list);
243#endif
244