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
22 static struct key *blacklist_keyring;
23
24 #ifdef CONFIG_SYSTEM_REVOCATION_LIST
25 extern __initconst const u8 revocation_certificate_list[];
26 extern __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 */
blacklist_vet_description(const char * desc)33 static 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
44 found_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 */
blacklist_preparse(struct key_preparsed_payload * prep)61 static int blacklist_preparse(struct key_preparsed_payload *prep)
62 {
63 if (prep->datalen > 0)
64 return -EINVAL;
65 return 0;
66 }
67
blacklist_free_preparse(struct key_preparsed_payload * prep)68 static void blacklist_free_preparse(struct key_preparsed_payload *prep)
69 {
70 }
71
blacklist_describe(const struct key * key,struct seq_file * m)72 static void blacklist_describe(const struct key *key, struct seq_file *m)
73 {
74 seq_puts(m, key->description);
75 }
76
77 static 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 */
mark_hash_blacklisted(const char * hash)90 int 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 */
is_hash_blacklisted(const u8 * hash,size_t hash_len,const char * type)116 int 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 }
143 EXPORT_SYMBOL_GPL(is_hash_blacklisted);
144
is_binary_blacklisted(const u8 * hash,size_t hash_len)145 int 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 }
152 EXPORT_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 */
add_key_to_revocation_list(const char * data,size_t size)160 int 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 */
is_key_on_revocation_list(struct pkcs7_message * pkcs7)184 int 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 */
blacklist_init(void)200 static 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 */
228 device_initcall(blacklist_init);
229
230 #ifdef CONFIG_SYSTEM_REVOCATION_LIST
231 /*
232 * Load the compiled-in list of revocation X.509 certificates.
233 */
load_revocation_certificate_list(void)234 static __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 }
242 late_initcall(load_revocation_certificate_list);
243 #endif
244
