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 */ 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 */ 61 static int blacklist_preparse(struct key_preparsed_payload *prep) 62 { 63 if (prep->datalen > 0) 64 return -EINVAL; 65 return 0; 66 } 67 68 static void blacklist_free_preparse(struct key_preparsed_payload *prep) 69 { 70 } 71 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 */ 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 */ 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); 144 145 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 */ 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 */ 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 */ 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 */ 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