crypto/asymmetric_keys/asymmetric_type.c

   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>
  14 #include <keys/asymmetric-parser.h>
  15 #include <linux/seq_file.h>
  16 #include <linux/module.h>
  17 #include <linux/slab.h>
  18 #include <linux/ctype.h>
  19 #include "asymmetric_keys.h"
  20
  21 MODULE_LICENSE("GPL");
  22
  23 static LIST_HEAD(asymmetric_key_parsers);
  24 static DECLARE_RWSEM(asymmetric_key_parsers_sem);
  25
  26 /**
  27  * asymmetric_key_generate_id: Construct an asymmetric key ID
  28  * @val_1: First binary blob
  29  * @len_1: Length of first binary blob
  30  * @val_2: Second binary blob
  31  * @len_2: Length of second binary blob
  32  *
  33  * Construct an asymmetric key ID from a pair of binary blobs.
  34  */
  35 struct asymmetric_key_id *asymmetric_key_generate_id(const void *val_1,
  36                                                      size_t len_1,
  37                                                      const void *val_2,
  38                                                      size_t len_2)
  39 {
  40         struct asymmetric_key_id *kid;
  41
  42         kid = kmalloc(sizeof(struct asymmetric_key_id) + len_1 + len_2,
  43                       GFP_KERNEL);
  44         if (!kid)
  45                 return ERR_PTR(-ENOMEM);
  46         kid->len = len_1 + len_2;
  47         memcpy(kid->data, val_1, len_1);
  48         memcpy(kid->data + len_1, val_2, len_2);
  49         return kid;
  50 }
  51 EXPORT_SYMBOL_GPL(asymmetric_key_generate_id);
  52
  53 /**
  54  * asymmetric_key_id_same - Return true if two asymmetric keys IDs are the same.
  55  * @kid_1, @kid_2: The key IDs to compare
  56  */
  57 bool asymmetric_key_id_same(const struct asymmetric_key_id *kid1,
  58                             const struct asymmetric_key_id *kid2)
  59 {
  60         if (!kid1 || !kid2)
  61                 return false;
  62         if (kid1->len != kid2->len)
  63                 return false;
  64         return memcmp(kid1->data, kid2->data, kid1->len) == 0;
  65 }
  66 EXPORT_SYMBOL_GPL(asymmetric_key_id_same);
  67
  68 /**
  69  * asymmetric_key_id_partial - Return true if two asymmetric keys IDs
  70  * partially match
  71  * @kid_1, @kid_2: The key IDs to compare
  72  */
  73 bool asymmetric_key_id_partial(const struct asymmetric_key_id *kid1,
  74                                const struct asymmetric_key_id *kid2)
  75 {
  76         if (!kid1 || !kid2)
  77                 return false;
  78         if (kid1->len < kid2->len)
  79                 return false;
  80         return memcmp(kid1->data + (kid1->len - kid2->len),
  81                       kid2->data, kid2->len) == 0;
  82 }
  83 EXPORT_SYMBOL_GPL(asymmetric_key_id_partial);
  84
  85 /**
  86  * asymmetric_match_key_ids - Search asymmetric key IDs
  87  * @kids: The list of key IDs to check
  88  * @match_id: The key ID we're looking for
  89  * @match: The match function to use
  90  */
  91 static bool asymmetric_match_key_ids(
  92         const struct asymmetric_key_ids *kids,
  93         const struct asymmetric_key_id *match_id,
  94         bool (*match)(const struct asymmetric_key_id *kid1,
  95                       const struct asymmetric_key_id *kid2))
  96 {
  97         int i;
  98
  99         if (!kids || !match_id)
 100                 return false;
 101         for (i = 0; i < ARRAY_SIZE(kids->id); i++)
 102                 if (match(kids->id[i], match_id))
 103                         return true;
 104         return false;
 105 }
 106
 107 /**
 108  * asymmetric_key_hex_to_key_id - Convert a hex string into a key ID.
 109  * @id: The ID as a hex string.
 110  */
 111 struct asymmetric_key_id *asymmetric_key_hex_to_key_id(const char *id)
 112 {
 113         struct asymmetric_key_id *match_id;
 114         size_t hexlen;
 115         int ret;
 116
 117         if (!*id)
 118                 return ERR_PTR(-EINVAL);
 119         hexlen = strlen(id);
 120         if (hexlen & 1)
 121                 return ERR_PTR(-EINVAL);
 122
 123         match_id = kmalloc(sizeof(struct asymmetric_key_id) + hexlen / 2,
 124                            GFP_KERNEL);
 125         if (!match_id)
 126                 return ERR_PTR(-ENOMEM);
 127         match_id->len = hexlen / 2;
 128         ret = hex2bin(match_id->data, id, hexlen / 2);
 129         if (ret < 0) {
 130                 kfree(match_id);
 131                 return ERR_PTR(-EINVAL);
 132         }
 133         return match_id;
 134 }
 135
 136 /*
 137  * Match asymmetric keys by an exact match on an ID.
 138  */
 139 static bool asymmetric_key_cmp(const struct key *key,
 140                                const struct key_match_data *match_data)
 141 {
 142         const struct asymmetric_key_ids *kids = asymmetric_key_ids(key);
 143         const struct asymmetric_key_id *match_id = match_data->preparsed;
 144
 145         return asymmetric_match_key_ids(kids, match_id,
 146                                         asymmetric_key_id_same);
 147 }
 148
 149 /*
 150  * Match asymmetric keys by a partial match on an IDs.
 151  */
 152 static bool asymmetric_key_cmp_partial(const struct key *key,
 153                                        const struct key_match_data *match_data)
 154 {
 155         const struct asymmetric_key_ids *kids = asymmetric_key_ids(key);
 156         const struct asymmetric_key_id *match_id = match_data->preparsed;
 157
 158         return asymmetric_match_key_ids(kids, match_id,
 159                                         asymmetric_key_id_partial);
 160 }
 161
 162 /*
 163  * Preparse the match criterion.  If we don't set lookup_type and cmp,
 164  * the default will be an exact match on the key description.
 165  *
 166  * There are some specifiers for matching key IDs rather than by the key
 167  * description:
 168  *
 169  *      "id:<id>" - find a key by partial match on any available ID
 170  *      "ex:<id>" - find a key by exact match on any available ID
 171  *
 172  * These have to be searched by iteration rather than by direct lookup because
 173  * the key is hashed according to its description.
 174  */
 175 static int asymmetric_key_match_preparse(struct key_match_data *match_data)
 176 {
 177         struct asymmetric_key_id *match_id;
 178         const char *spec = match_data->raw_data;
 179         const char *id;
 180         bool (*cmp)(const struct key *, const struct key_match_data *) =
 181                 asymmetric_key_cmp;
 182
 183         if (!spec || !*spec)
 184                 return -EINVAL;
 185         if (spec[0] == 'i' &&
 186             spec[1] == 'd' &&
 187             spec[2] == ':') {
 188                 id = spec + 3;
 189                 cmp = asymmetric_key_cmp_partial;
 190         } else if (spec[0] == 'e' &&
 191                    spec[1] == 'x' &&
 192                    spec[2] == ':') {
 193                 id = spec + 3;
 194         } else {
 195                 goto default_match;
 196         }
 197
 198         match_id = asymmetric_key_hex_to_key_id(id);
 199         if (IS_ERR(match_id))
 200                 return PTR_ERR(match_id);
 201
 202         match_data->preparsed = match_id;
 203         match_data->cmp = cmp;
 204         match_data->lookup_type = KEYRING_SEARCH_LOOKUP_ITERATE;
 205         return 0;
 206
 207 default_match:
 208         return 0;
 209 }
 210
 211 /*
 212  * Free the preparsed the match criterion.
 213  */
 214 static void asymmetric_key_match_free(struct key_match_data *match_data)
 215 {
 216         kfree(match_data->preparsed);
 217 }
 218
 219 /*
 220  * Describe the asymmetric key
 221  */
 222 static void asymmetric_key_describe(const struct key *key, struct seq_file *m)
 223 {
 224         const struct asymmetric_key_subtype *subtype = asymmetric_key_subtype(key);
 225         const struct asymmetric_key_ids *kids = asymmetric_key_ids(key);
 226         const struct asymmetric_key_id *kid;
 227         const unsigned char *p;
 228         int n;
 229
 230         seq_puts(m, key->description);
 231
 232         if (subtype) {
 233                 seq_puts(m, ": ");
 234                 subtype->describe(key, m);
 235
 236                 if (kids && kids->id[1]) {
 237                         kid = kids->id[1];
 238                         seq_putc(m, ' ');
 239                         n = kid->len;
 240                         p = kid->data;
 241                         if (n > 4) {
 242                                 p += n - 4;
 243                                 n = 4;
 244                         }
 245                         seq_printf(m, "%*phN", n, p);
 246                 }
 247
 248                 seq_puts(m, " [");
 249                 /* put something here to indicate the key's capabilities */
 250                 seq_putc(m, ']');
 251         }
 252 }
 253
 254 /*
 255  * Preparse a asymmetric payload to get format the contents appropriately for the
 256  * internal payload to cut down on the number of scans of the data performed.
 257  *
 258  * We also generate a proposed description from the contents of the key that
 259  * can be used to name the key if the user doesn't want to provide one.
 260  */
 261 static int asymmetric_key_preparse(struct key_preparsed_payload *prep)
 262 {
 263         struct asymmetric_key_parser *parser;
 264         int ret;
 265
 266         pr_devel("==>%s()\n", __func__);
 267
 268         if (prep->datalen == 0)
 269                 return -EINVAL;
 270
 271         down_read(&asymmetric_key_parsers_sem);
 272
 273         ret = -EBADMSG;
 274         list_for_each_entry(parser, &asymmetric_key_parsers, link) {
 275                 pr_debug("Trying parser '%s'\n", parser->name);
 276
 277                 ret = parser->parse(prep);
 278                 if (ret != -EBADMSG) {
 279                         pr_debug("Parser recognised the format (ret %d)\n",
 280                                  ret);
 281                         break;
 282                 }
 283         }
 284
 285         up_read(&asymmetric_key_parsers_sem);
 286         pr_devel("<==%s() = %d\n", __func__, ret);
 287         return ret;
 288 }
 289
 290 /*
 291  * Clean up the preparse data
 292  */
 293 static void asymmetric_key_free_preparse(struct key_preparsed_payload *prep)
 294 {
 295         struct asymmetric_key_subtype *subtype = prep->type_data[0];
 296         struct asymmetric_key_ids *kids = prep->type_data[1];
 297         int i;
 298
 299         pr_devel("==>%s()\n", __func__);
 300
 301         if (subtype) {
 302                 subtype->destroy(prep->payload[0]);
 303                 module_put(subtype->owner);
 304         }
 305         if (kids) {
 306                 for (i = 0; i < ARRAY_SIZE(kids->id); i++)
 307                         kfree(kids->id[i]);
 308                 kfree(kids);
 309         }
 310         kfree(prep->description);
 311 }
 312
 313 /*
 314  * dispose of the data dangling from the corpse of a asymmetric key
 315  */
 316 static void asymmetric_key_destroy(struct key *key)
 317 {
 318         struct asymmetric_key_subtype *subtype = asymmetric_key_subtype(key);
 319         struct asymmetric_key_ids *kids = key->type_data.p[1];
 320
 321         if (subtype) {
 322                 subtype->destroy(key->payload.data);
 323                 module_put(subtype->owner);
 324                 key->type_data.p[0] = NULL;
 325         }
 326
 327         if (kids) {
 328                 kfree(kids->id[0]);
 329                 kfree(kids->id[1]);
 330                 kfree(kids);
 331                 key->type_data.p[1] = NULL;
 332         }
 333 }
 334
 335 struct key_type key_type_asymmetric = {
 336         .name           = "asymmetric",
 337         .preparse       = asymmetric_key_preparse,
 338         .free_preparse  = asymmetric_key_free_preparse,
 339         .instantiate    = generic_key_instantiate,
 340         .match_preparse = asymmetric_key_match_preparse,
 341         .match_free     = asymmetric_key_match_free,
 342         .destroy        = asymmetric_key_destroy,
 343         .describe       = asymmetric_key_describe,
 344 };
 345 EXPORT_SYMBOL_GPL(key_type_asymmetric);
 346
 347 /**
 348  * register_asymmetric_key_parser - Register a asymmetric key blob parser
 349  * @parser: The parser to register
 350  */
 351 int register_asymmetric_key_parser(struct asymmetric_key_parser *parser)
 352 {
 353         struct asymmetric_key_parser *cursor;
 354         int ret;
 355
 356         down_write(&asymmetric_key_parsers_sem);
 357
 358         list_for_each_entry(cursor, &asymmetric_key_parsers, link) {
 359                 if (strcmp(cursor->name, parser->name) == 0) {
 360                         pr_err("Asymmetric key parser '%s' already registered\n",
 361                                parser->name);
 362                         ret = -EEXIST;
 363                         goto out;
 364                 }
 365         }
 366
 367         list_add_tail(&parser->link, &asymmetric_key_parsers);
 368
 369         pr_notice("Asymmetric key parser '%s' registered\n", parser->name);
 370         ret = 0;
 371
 372 out:
 373         up_write(&asymmetric_key_parsers_sem);
 374         return ret;
 375 }
 376 EXPORT_SYMBOL_GPL(register_asymmetric_key_parser);
 377
 378 /**
 379  * unregister_asymmetric_key_parser - Unregister a asymmetric key blob parser
 380  * @parser: The parser to unregister
 381  */
 382 void unregister_asymmetric_key_parser(struct asymmetric_key_parser *parser)
 383 {
 384         down_write(&asymmetric_key_parsers_sem);
 385         list_del(&parser->link);
 386         up_write(&asymmetric_key_parsers_sem);
 387
 388         pr_notice("Asymmetric key parser '%s' unregistered\n", parser->name);
 389 }
 390 EXPORT_SYMBOL_GPL(unregister_asymmetric_key_parser);
 391
 392 /*
 393  * Module stuff
 394  */
 395 static int __init asymmetric_key_init(void)
 396 {
 397         return register_key_type(&key_type_asymmetric);
 398 }
 399
 400 static void __exit asymmetric_key_cleanup(void)
 401 {
 402         unregister_key_type(&key_type_asymmetric);
 403 }
 404
 405 module_init(asymmetric_key_init);
 406 module_exit(asymmetric_key_cleanup);