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 <linux/uidgid.h>
 18#include <keys/system_keyring.h>
 19#include "blacklist.h"
 20#include "common.h"
 21
 22static struct key *blacklist_keyring;
 23
 24#ifdef CONFIG_SYSTEM_REVOCATION_LIST
 25extern __initconst const u8 revocation_certificate_list[];
 26extern __initconst const unsigned long revocation_certificate_list_size;
 27#endif
 28
 29/*
 30 * The description must be a type prefix, a colon and then an even number of
 31 * hex digits.  The hash is kept in the description.
 32 */
 33static int blacklist_vet_description(const char *desc)
 34{
 35	int n = 0;
 36
 37	if (*desc == ':')
 38		return -EINVAL;
 39	for (; *desc; desc++)
 40		if (*desc == ':')
 41			goto found_colon;
 42	return -EINVAL;
 43
 44found_colon:
 45	desc++;
 46	for (; *desc; desc++) {
 47		if (!isxdigit(*desc) || isupper(*desc))
 48			return -EINVAL;
 49		n++;
 50	}
 51
 52	if (n == 0 || n & 1)
 53		return -EINVAL;
 54	return 0;
 55}
 56
 57/*
 58 * The hash to be blacklisted is expected to be in the description.  There will
 59 * be no payload.
 60 */
 61static int blacklist_preparse(struct key_preparsed_payload *prep)
 62{
 63	if (prep->datalen > 0)
 64		return -EINVAL;
 65	return 0;
 66}
 67
 68static void blacklist_free_preparse(struct key_preparsed_payload *prep)
 69{
 70}
 71
 72static void blacklist_describe(const struct key *key, struct seq_file *m)
 73{
 74	seq_puts(m, key->description);
 75}
 76
 77static struct key_type key_type_blacklist = {
 78	.name			= "blacklist",
 79	.vet_description	= blacklist_vet_description,
 80	.preparse		= blacklist_preparse,
 81	.free_preparse		= blacklist_free_preparse,
 82	.instantiate		= generic_key_instantiate,
 83	.describe		= blacklist_describe,
 84};
 85
 86/**
 87 * mark_hash_blacklisted - Add a hash to the system blacklist
 88 * @hash: The hash as a hex string with a type prefix (eg. "tbs:23aa429783")
 89 */
 90int mark_hash_blacklisted(const char *hash)
 91{
 92	key_ref_t key;
 93
 94	key = key_create_or_update(make_key_ref(blacklist_keyring, true),
 95				   "blacklist",
 96				   hash,
 97				   NULL,
 98				   0,
 99				   ((KEY_POS_ALL & ~KEY_POS_SETATTR) |
100				    KEY_USR_VIEW),
101				   KEY_ALLOC_NOT_IN_QUOTA |
102				   KEY_ALLOC_BUILT_IN);
103	if (IS_ERR(key)) {
104		pr_err("Problem blacklisting hash (%ld)\n", PTR_ERR(key));
105		return PTR_ERR(key);
106	}
107	return 0;
108}
109
110/**
111 * is_hash_blacklisted - Determine if a hash is blacklisted
112 * @hash: The hash to be checked as a binary blob
113 * @hash_len: The length of the binary hash
114 * @type: Type of hash
115 */
116int is_hash_blacklisted(const u8 *hash, size_t hash_len, const char *type)
117{
118	key_ref_t kref;
119	size_t type_len = strlen(type);
120	char *buffer, *p;
121	int ret = 0;
122
123	buffer = kmalloc(type_len + 1 + hash_len * 2 + 1, GFP_KERNEL);
124	if (!buffer)
125		return -ENOMEM;
126	p = memcpy(buffer, type, type_len);
127	p += type_len;
128	*p++ = ':';
129	bin2hex(p, hash, hash_len);
130	p += hash_len * 2;
131	*p = 0;
132
133	kref = keyring_search(make_key_ref(blacklist_keyring, true),
134			      &key_type_blacklist, buffer, false);
135	if (!IS_ERR(kref)) {
136		key_ref_put(kref);
137		ret = -EKEYREJECTED;
138	}
139
140	kfree(buffer);
141	return ret;
142}
143EXPORT_SYMBOL_GPL(is_hash_blacklisted);
144
145int is_binary_blacklisted(const u8 *hash, size_t hash_len)
146{
147	if (is_hash_blacklisted(hash, hash_len, "bin") == -EKEYREJECTED)
148		return -EPERM;
149
150	return 0;
151}
152EXPORT_SYMBOL_GPL(is_binary_blacklisted);
153
154#ifdef CONFIG_SYSTEM_REVOCATION_LIST
155/**
156 * add_key_to_revocation_list - Add a revocation certificate to the blacklist
157 * @data: The data blob containing the certificate
158 * @size: The size of data blob
159 */
160int add_key_to_revocation_list(const char *data, size_t size)
161{
162	key_ref_t key;
163
164	key = key_create_or_update(make_key_ref(blacklist_keyring, true),
165				   "asymmetric",
166				   NULL,
167				   data,
168				   size,
169				   ((KEY_POS_ALL & ~KEY_POS_SETATTR) | KEY_USR_VIEW),
170				   KEY_ALLOC_NOT_IN_QUOTA | KEY_ALLOC_BUILT_IN);
171
172	if (IS_ERR(key)) {
173		pr_err("Problem with revocation key (%ld)\n", PTR_ERR(key));
174		return PTR_ERR(key);
175	}
176
177	return 0;
178}
179
180/**
181 * is_key_on_revocation_list - Determine if the key for a PKCS#7 message is revoked
182 * @pkcs7: The PKCS#7 message to check
183 */
184int is_key_on_revocation_list(struct pkcs7_message *pkcs7)
185{
186	int ret;
187
188	ret = pkcs7_validate_trust(pkcs7, blacklist_keyring);
189
190	if (ret == 0)
191		return -EKEYREJECTED;
192
193	return -ENOKEY;
194}
195#endif
196
197/*
198 * Initialise the blacklist
199 */
200static int __init blacklist_init(void)
201{
202	const char *const *bl;
203
204	if (register_key_type(&key_type_blacklist) < 0)
205		panic("Can't allocate system blacklist key type\n");
206
207	blacklist_keyring =
208		keyring_alloc(".blacklist",
209			      GLOBAL_ROOT_UID, GLOBAL_ROOT_GID, 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