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b4d0d230 | 1 | // SPDX-License-Identifier: GPL-2.0-or-later |
734114f8 DH |
2 | /* System hash blacklist. |
3 | * | |
4 | * Copyright (C) 2016 Red Hat, Inc. All Rights Reserved. | |
5 | * Written by David Howells (dhowells@redhat.com) | |
734114f8 DH |
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 | ||
20 | static struct key *blacklist_keyring; | |
21 | ||
22 | /* | |
23 | * The description must be a type prefix, a colon and then an even number of | |
24 | * hex digits. The hash is kept in the description. | |
25 | */ | |
26 | static int blacklist_vet_description(const char *desc) | |
27 | { | |
28 | int n = 0; | |
29 | ||
30 | if (*desc == ':') | |
31 | return -EINVAL; | |
32 | for (; *desc; desc++) | |
33 | if (*desc == ':') | |
34 | goto found_colon; | |
35 | return -EINVAL; | |
36 | ||
37 | found_colon: | |
38 | desc++; | |
39 | for (; *desc; desc++) { | |
40 | if (!isxdigit(*desc)) | |
41 | return -EINVAL; | |
42 | n++; | |
43 | } | |
44 | ||
45 | if (n == 0 || n & 1) | |
46 | return -EINVAL; | |
47 | return 0; | |
48 | } | |
49 | ||
50 | /* | |
51 | * The hash to be blacklisted is expected to be in the description. There will | |
52 | * be no payload. | |
53 | */ | |
54 | static int blacklist_preparse(struct key_preparsed_payload *prep) | |
55 | { | |
56 | if (prep->datalen > 0) | |
57 | return -EINVAL; | |
58 | return 0; | |
59 | } | |
60 | ||
61 | static void blacklist_free_preparse(struct key_preparsed_payload *prep) | |
62 | { | |
63 | } | |
64 | ||
65 | static void blacklist_describe(const struct key *key, struct seq_file *m) | |
66 | { | |
67 | seq_puts(m, key->description); | |
68 | } | |
69 | ||
70 | static struct key_type key_type_blacklist = { | |
71 | .name = "blacklist", | |
72 | .vet_description = blacklist_vet_description, | |
73 | .preparse = blacklist_preparse, | |
74 | .free_preparse = blacklist_free_preparse, | |
75 | .instantiate = generic_key_instantiate, | |
76 | .describe = blacklist_describe, | |
77 | }; | |
78 | ||
79 | /** | |
80 | * mark_hash_blacklisted - Add a hash to the system blacklist | |
81 | * @hash - The hash as a hex string with a type prefix (eg. "tbs:23aa429783") | |
82 | */ | |
83 | int mark_hash_blacklisted(const char *hash) | |
84 | { | |
85 | key_ref_t key; | |
86 | ||
87 | key = key_create_or_update(make_key_ref(blacklist_keyring, true), | |
88 | "blacklist", | |
89 | hash, | |
90 | NULL, | |
91 | 0, | |
028db3e2 LT |
92 | ((KEY_POS_ALL & ~KEY_POS_SETATTR) | |
93 | KEY_USR_VIEW), | |
734114f8 DH |
94 | KEY_ALLOC_NOT_IN_QUOTA | |
95 | KEY_ALLOC_BUILT_IN); | |
96 | if (IS_ERR(key)) { | |
97 | pr_err("Problem blacklisting hash (%ld)\n", PTR_ERR(key)); | |
98 | return PTR_ERR(key); | |
99 | } | |
100 | return 0; | |
101 | } | |
102 | ||
103 | /** | |
104 | * is_hash_blacklisted - Determine if a hash is blacklisted | |
105 | * @hash: The hash to be checked as a binary blob | |
106 | * @hash_len: The length of the binary hash | |
107 | * @type: Type of hash | |
108 | */ | |
109 | int is_hash_blacklisted(const u8 *hash, size_t hash_len, const char *type) | |
110 | { | |
111 | key_ref_t kref; | |
112 | size_t type_len = strlen(type); | |
113 | char *buffer, *p; | |
114 | int ret = 0; | |
115 | ||
116 | buffer = kmalloc(type_len + 1 + hash_len * 2 + 1, GFP_KERNEL); | |
117 | if (!buffer) | |
118 | return -ENOMEM; | |
119 | p = memcpy(buffer, type, type_len); | |
120 | p += type_len; | |
121 | *p++ = ':'; | |
122 | bin2hex(p, hash, hash_len); | |
123 | p += hash_len * 2; | |
124 | *p = 0; | |
125 | ||
126 | kref = keyring_search(make_key_ref(blacklist_keyring, true), | |
dcf49dbc | 127 | &key_type_blacklist, buffer, false); |
734114f8 DH |
128 | if (!IS_ERR(kref)) { |
129 | key_ref_put(kref); | |
130 | ret = -EKEYREJECTED; | |
131 | } | |
132 | ||
133 | kfree(buffer); | |
134 | return ret; | |
135 | } | |
136 | EXPORT_SYMBOL_GPL(is_hash_blacklisted); | |
137 | ||
2434f7d2 NJ |
138 | int is_binary_blacklisted(const u8 *hash, size_t hash_len) |
139 | { | |
140 | if (is_hash_blacklisted(hash, hash_len, "bin") == -EKEYREJECTED) | |
141 | return -EPERM; | |
142 | ||
143 | return 0; | |
144 | } | |
145 | EXPORT_SYMBOL_GPL(is_binary_blacklisted); | |
146 | ||
734114f8 | 147 | /* |
6e7c2b4d | 148 | * Initialise the blacklist |
734114f8 DH |
149 | */ |
150 | static int __init blacklist_init(void) | |
151 | { | |
152 | const char *const *bl; | |
153 | ||
154 | if (register_key_type(&key_type_blacklist) < 0) | |
155 | panic("Can't allocate system blacklist key type\n"); | |
156 | ||
157 | blacklist_keyring = | |
158 | keyring_alloc(".blacklist", | |
159 | KUIDT_INIT(0), KGIDT_INIT(0), | |
160 | current_cred(), | |
028db3e2 LT |
161 | (KEY_POS_ALL & ~KEY_POS_SETATTR) | |
162 | KEY_USR_VIEW | KEY_USR_READ | | |
163 | KEY_USR_SEARCH, | |
734114f8 DH |
164 | KEY_ALLOC_NOT_IN_QUOTA | |
165 | KEY_FLAG_KEEP, | |
166 | NULL, NULL); | |
167 | if (IS_ERR(blacklist_keyring)) | |
168 | panic("Can't allocate system blacklist keyring\n"); | |
169 | ||
170 | for (bl = blacklist_hashes; *bl; bl++) | |
171 | if (mark_hash_blacklisted(*bl) < 0) | |
172 | pr_err("- blacklisting failed\n"); | |
173 | return 0; | |
174 | } | |
175 | ||
176 | /* | |
177 | * Must be initialised before we try and load the keys into the keyring. | |
178 | */ | |
179 | device_initcall(blacklist_init); |