security/keys/encrypted-keys/ecryptfs_format.c

   1 /*
   2  * ecryptfs_format.c: helper functions for the encrypted key type
   3  *
   4  * Copyright (C) 2006 International Business Machines Corp.
   5  * Copyright (C) 2010 Politecnico di Torino, Italy
   6  *                    TORSEC group -- http://security.polito.it
   7  *
   8  * Authors:
   9  * Michael A. Halcrow <mahalcro@us.ibm.com>
  10  * Tyler Hicks <tyhicks@ou.edu>
  11  * Roberto Sassu <roberto.sassu@polito.it>
  12  *
  13  * This program is free software; you can redistribute it and/or modify
  14  * it under the terms of the GNU General Public License as published by
  15  * the Free Software Foundation, version 2 of the License.
  16  */
  17
  18 #include <linux/module.h>
  19 #include "ecryptfs_format.h"
  20
  21 u8 *ecryptfs_get_auth_tok_key(struct ecryptfs_auth_tok *auth_tok)
  22 {
  23         return auth_tok->token.password.session_key_encryption_key;
  24 }
  25 EXPORT_SYMBOL(ecryptfs_get_auth_tok_key);
  26
  27 /*
  28  * ecryptfs_get_versions()
  29  *
  30  * Source code taken from the software 'ecryptfs-utils' version 83.
  31  *
  32  */
  33 void ecryptfs_get_versions(int *major, int *minor, int *file_version)
  34 {
  35         *major = ECRYPTFS_VERSION_MAJOR;
  36         *minor = ECRYPTFS_VERSION_MINOR;
  37         if (file_version)
  38                 *file_version = ECRYPTFS_SUPPORTED_FILE_VERSION;
  39 }
  40 EXPORT_SYMBOL(ecryptfs_get_versions);
  41
  42 /*
  43  * ecryptfs_fill_auth_tok - fill the ecryptfs_auth_tok structure
  44  *
  45  * Fill the ecryptfs_auth_tok structure with required ecryptfs data.
  46  * The source code is inspired to the original function generate_payload()
  47  * shipped with the software 'ecryptfs-utils' version 83.
  48  *
  49  */
  50 int ecryptfs_fill_auth_tok(struct ecryptfs_auth_tok *auth_tok,
  51                            const char *key_desc)
  52 {
  53         int major, minor;
  54
  55         ecryptfs_get_versions(&major, &minor, NULL);
  56         auth_tok->version = (((uint16_t)(major << 8) & 0xFF00)
  57                              | ((uint16_t)minor & 0x00FF));
  58         auth_tok->token_type = ECRYPTFS_PASSWORD;
  59         strncpy((char *)auth_tok->token.password.signature, key_desc,
  60                 ECRYPTFS_PASSWORD_SIG_SIZE);
  61         auth_tok->token.password.session_key_encryption_key_bytes =
  62                 ECRYPTFS_MAX_KEY_BYTES;
  63         /*
  64          * Removed auth_tok->token.password.salt and
  65          * auth_tok->token.password.session_key_encryption_key
  66          * initialization from the original code
  67          */
  68         /* TODO: Make the hash parameterizable via policy */
  69         auth_tok->token.password.flags |=
  70                 ECRYPTFS_SESSION_KEY_ENCRYPTION_KEY_SET;
  71         /* The kernel code will encrypt the session key. */
  72         auth_tok->session_key.encrypted_key[0] = 0;
  73         auth_tok->session_key.encrypted_key_size = 0;
  74         /* Default; subject to change by kernel eCryptfs */
  75         auth_tok->token.password.hash_algo = PGP_DIGEST_ALGO_SHA512;
  76         auth_tok->token.password.flags &= ~(ECRYPTFS_PERSISTENT_PASSWORD);
  77         return 0;
  78 }
  79 EXPORT_SYMBOL(ecryptfs_fill_auth_tok);
  80
  81 MODULE_LICENSE("GPL");