David Howells | 964f3b3 | 2012-09-13 15:17:21 +0100 | [diff] [blame] | 1 | /* Asymmetric public-key cryptography key type |
| 2 | * |
| 3 | * See Documentation/security/asymmetric-keys.txt |
| 4 | * |
| 5 | * Copyright (C) 2012 Red Hat, Inc. All Rights Reserved. |
| 6 | * Written by David Howells (dhowells@redhat.com) |
| 7 | * |
| 8 | * This program is free software; you can redistribute it and/or |
| 9 | * modify it under the terms of the GNU General Public Licence |
| 10 | * as published by the Free Software Foundation; either version |
| 11 | * 2 of the Licence, or (at your option) any later version. |
| 12 | */ |
| 13 | #include <keys/asymmetric-subtype.h> |
David Howells | 46c6f17 | 2012-09-13 15:17:32 +0100 | [diff] [blame] | 14 | #include <keys/asymmetric-parser.h> |
David Howells | 964f3b3 | 2012-09-13 15:17:21 +0100 | [diff] [blame] | 15 | #include <linux/seq_file.h> |
| 16 | #include <linux/module.h> |
| 17 | #include <linux/slab.h> |
| 18 | #include "asymmetric_keys.h" |
| 19 | |
| 20 | MODULE_LICENSE("GPL"); |
| 21 | |
David Howells | 46c6f17 | 2012-09-13 15:17:32 +0100 | [diff] [blame] | 22 | static LIST_HEAD(asymmetric_key_parsers); |
| 23 | static DECLARE_RWSEM(asymmetric_key_parsers_sem); |
| 24 | |
David Howells | 964f3b3 | 2012-09-13 15:17:21 +0100 | [diff] [blame] | 25 | /* |
| 26 | * Match asymmetric keys on (part of) their name |
| 27 | * We have some shorthand methods for matching keys. We allow: |
| 28 | * |
| 29 | * "<desc>" - request a key by description |
| 30 | * "id:<id>" - request a key matching the ID |
| 31 | * "<subtype>:<id>" - request a key of a subtype |
| 32 | */ |
| 33 | static int asymmetric_key_match(const struct key *key, const void *description) |
| 34 | { |
| 35 | const struct asymmetric_key_subtype *subtype = asymmetric_key_subtype(key); |
| 36 | const char *spec = description; |
| 37 | const char *id, *kid; |
| 38 | ptrdiff_t speclen; |
| 39 | size_t idlen, kidlen; |
| 40 | |
| 41 | if (!subtype || !spec || !*spec) |
| 42 | return 0; |
| 43 | |
| 44 | /* See if the full key description matches as is */ |
| 45 | if (key->description && strcmp(key->description, description) == 0) |
| 46 | return 1; |
| 47 | |
| 48 | /* All tests from here on break the criterion description into a |
| 49 | * specifier, a colon and then an identifier. |
| 50 | */ |
| 51 | id = strchr(spec, ':'); |
| 52 | if (!id) |
| 53 | return 0; |
| 54 | |
| 55 | speclen = id - spec; |
| 56 | id++; |
| 57 | |
| 58 | /* Anything after here requires a partial match on the ID string */ |
| 59 | kid = asymmetric_key_id(key); |
| 60 | if (!kid) |
| 61 | return 0; |
| 62 | |
| 63 | idlen = strlen(id); |
| 64 | kidlen = strlen(kid); |
| 65 | if (idlen > kidlen) |
| 66 | return 0; |
| 67 | |
| 68 | kid += kidlen - idlen; |
| 69 | if (strcasecmp(id, kid) != 0) |
| 70 | return 0; |
| 71 | |
| 72 | if (speclen == 2 && |
| 73 | memcmp(spec, "id", 2) == 0) |
| 74 | return 1; |
| 75 | |
| 76 | if (speclen == subtype->name_len && |
| 77 | memcmp(spec, subtype->name, speclen) == 0) |
| 78 | return 1; |
| 79 | |
| 80 | return 0; |
| 81 | } |
| 82 | |
| 83 | /* |
| 84 | * Describe the asymmetric key |
| 85 | */ |
| 86 | static void asymmetric_key_describe(const struct key *key, struct seq_file *m) |
| 87 | { |
| 88 | const struct asymmetric_key_subtype *subtype = asymmetric_key_subtype(key); |
| 89 | const char *kid = asymmetric_key_id(key); |
| 90 | size_t n; |
| 91 | |
| 92 | seq_puts(m, key->description); |
| 93 | |
| 94 | if (subtype) { |
| 95 | seq_puts(m, ": "); |
| 96 | subtype->describe(key, m); |
| 97 | |
| 98 | if (kid) { |
| 99 | seq_putc(m, ' '); |
| 100 | n = strlen(kid); |
| 101 | if (n <= 8) |
| 102 | seq_puts(m, kid); |
| 103 | else |
| 104 | seq_puts(m, kid + n - 8); |
| 105 | } |
| 106 | |
| 107 | seq_puts(m, " ["); |
| 108 | /* put something here to indicate the key's capabilities */ |
| 109 | seq_putc(m, ']'); |
| 110 | } |
| 111 | } |
| 112 | |
| 113 | /* |
David Howells | 46c6f17 | 2012-09-13 15:17:32 +0100 | [diff] [blame] | 114 | * Preparse a asymmetric payload to get format the contents appropriately for the |
| 115 | * internal payload to cut down on the number of scans of the data performed. |
| 116 | * |
| 117 | * We also generate a proposed description from the contents of the key that |
| 118 | * can be used to name the key if the user doesn't want to provide one. |
| 119 | */ |
| 120 | static int asymmetric_key_preparse(struct key_preparsed_payload *prep) |
| 121 | { |
| 122 | struct asymmetric_key_parser *parser; |
| 123 | int ret; |
| 124 | |
| 125 | pr_devel("==>%s()\n", __func__); |
| 126 | |
| 127 | if (prep->datalen == 0) |
| 128 | return -EINVAL; |
| 129 | |
| 130 | down_read(&asymmetric_key_parsers_sem); |
| 131 | |
| 132 | ret = -EBADMSG; |
| 133 | list_for_each_entry(parser, &asymmetric_key_parsers, link) { |
| 134 | pr_debug("Trying parser '%s'\n", parser->name); |
| 135 | |
| 136 | ret = parser->parse(prep); |
| 137 | if (ret != -EBADMSG) { |
| 138 | pr_debug("Parser recognised the format (ret %d)\n", |
| 139 | ret); |
| 140 | break; |
| 141 | } |
| 142 | } |
| 143 | |
| 144 | up_read(&asymmetric_key_parsers_sem); |
| 145 | pr_devel("<==%s() = %d\n", __func__, ret); |
| 146 | return ret; |
| 147 | } |
| 148 | |
| 149 | /* |
| 150 | * Clean up the preparse data |
| 151 | */ |
| 152 | static void asymmetric_key_free_preparse(struct key_preparsed_payload *prep) |
| 153 | { |
| 154 | struct asymmetric_key_subtype *subtype = prep->type_data[0]; |
| 155 | |
| 156 | pr_devel("==>%s()\n", __func__); |
| 157 | |
| 158 | if (subtype) { |
| 159 | subtype->destroy(prep->payload); |
| 160 | module_put(subtype->owner); |
| 161 | } |
| 162 | kfree(prep->type_data[1]); |
| 163 | kfree(prep->description); |
| 164 | } |
| 165 | |
| 166 | /* |
David Howells | 964f3b3 | 2012-09-13 15:17:21 +0100 | [diff] [blame] | 167 | * Instantiate a asymmetric_key defined key. The key was preparsed, so we just |
| 168 | * have to transfer the data here. |
| 169 | */ |
| 170 | static int asymmetric_key_instantiate(struct key *key, struct key_preparsed_payload *prep) |
| 171 | { |
David Howells | 46c6f17 | 2012-09-13 15:17:32 +0100 | [diff] [blame] | 172 | int ret; |
| 173 | |
| 174 | pr_devel("==>%s()\n", __func__); |
| 175 | |
| 176 | ret = key_payload_reserve(key, prep->quotalen); |
| 177 | if (ret == 0) { |
| 178 | key->type_data.p[0] = prep->type_data[0]; |
| 179 | key->type_data.p[1] = prep->type_data[1]; |
| 180 | key->payload.data = prep->payload; |
| 181 | prep->type_data[0] = NULL; |
| 182 | prep->type_data[1] = NULL; |
| 183 | prep->payload = NULL; |
| 184 | } |
| 185 | pr_devel("<==%s() = %d\n", __func__, ret); |
| 186 | return ret; |
David Howells | 964f3b3 | 2012-09-13 15:17:21 +0100 | [diff] [blame] | 187 | } |
| 188 | |
| 189 | /* |
| 190 | * dispose of the data dangling from the corpse of a asymmetric key |
| 191 | */ |
| 192 | static void asymmetric_key_destroy(struct key *key) |
| 193 | { |
| 194 | struct asymmetric_key_subtype *subtype = asymmetric_key_subtype(key); |
| 195 | if (subtype) { |
| 196 | subtype->destroy(key->payload.data); |
| 197 | module_put(subtype->owner); |
| 198 | key->type_data.p[0] = NULL; |
| 199 | } |
| 200 | kfree(key->type_data.p[1]); |
| 201 | key->type_data.p[1] = NULL; |
| 202 | } |
| 203 | |
| 204 | struct key_type key_type_asymmetric = { |
| 205 | .name = "asymmetric", |
David Howells | 46c6f17 | 2012-09-13 15:17:32 +0100 | [diff] [blame] | 206 | .preparse = asymmetric_key_preparse, |
| 207 | .free_preparse = asymmetric_key_free_preparse, |
David Howells | 964f3b3 | 2012-09-13 15:17:21 +0100 | [diff] [blame] | 208 | .instantiate = asymmetric_key_instantiate, |
| 209 | .match = asymmetric_key_match, |
| 210 | .destroy = asymmetric_key_destroy, |
| 211 | .describe = asymmetric_key_describe, |
| 212 | }; |
| 213 | EXPORT_SYMBOL_GPL(key_type_asymmetric); |
| 214 | |
David Howells | 46c6f17 | 2012-09-13 15:17:32 +0100 | [diff] [blame] | 215 | /** |
| 216 | * register_asymmetric_key_parser - Register a asymmetric key blob parser |
| 217 | * @parser: The parser to register |
| 218 | */ |
| 219 | int register_asymmetric_key_parser(struct asymmetric_key_parser *parser) |
| 220 | { |
| 221 | struct asymmetric_key_parser *cursor; |
| 222 | int ret; |
| 223 | |
| 224 | down_write(&asymmetric_key_parsers_sem); |
| 225 | |
| 226 | list_for_each_entry(cursor, &asymmetric_key_parsers, link) { |
| 227 | if (strcmp(cursor->name, parser->name) == 0) { |
| 228 | pr_err("Asymmetric key parser '%s' already registered\n", |
| 229 | parser->name); |
| 230 | ret = -EEXIST; |
| 231 | goto out; |
| 232 | } |
| 233 | } |
| 234 | |
| 235 | list_add_tail(&parser->link, &asymmetric_key_parsers); |
| 236 | |
| 237 | pr_notice("Asymmetric key parser '%s' registered\n", parser->name); |
| 238 | ret = 0; |
| 239 | |
| 240 | out: |
| 241 | up_write(&asymmetric_key_parsers_sem); |
| 242 | return ret; |
| 243 | } |
| 244 | EXPORT_SYMBOL_GPL(register_asymmetric_key_parser); |
| 245 | |
| 246 | /** |
| 247 | * unregister_asymmetric_key_parser - Unregister a asymmetric key blob parser |
| 248 | * @parser: The parser to unregister |
| 249 | */ |
| 250 | void unregister_asymmetric_key_parser(struct asymmetric_key_parser *parser) |
| 251 | { |
| 252 | down_write(&asymmetric_key_parsers_sem); |
| 253 | list_del(&parser->link); |
| 254 | up_write(&asymmetric_key_parsers_sem); |
| 255 | |
| 256 | pr_notice("Asymmetric key parser '%s' unregistered\n", parser->name); |
| 257 | } |
| 258 | EXPORT_SYMBOL_GPL(unregister_asymmetric_key_parser); |
| 259 | |
David Howells | 964f3b3 | 2012-09-13 15:17:21 +0100 | [diff] [blame] | 260 | /* |
| 261 | * Module stuff |
| 262 | */ |
| 263 | static int __init asymmetric_key_init(void) |
| 264 | { |
| 265 | return register_key_type(&key_type_asymmetric); |
| 266 | } |
| 267 | |
| 268 | static void __exit asymmetric_key_cleanup(void) |
| 269 | { |
| 270 | unregister_key_type(&key_type_asymmetric); |
| 271 | } |
| 272 | |
| 273 | module_init(asymmetric_key_init); |
| 274 | module_exit(asymmetric_key_cleanup); |