crypto/asymmetric_keys/pkcs7_key_type.c

   1 /* Testing module to load key from trusted PKCS#7 message
   2  *
   3  * Copyright (C) 2014 Red Hat, Inc. All Rights Reserved.
   4  * Written by David Howells (dhowells@redhat.com)
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public Licence
   8  * as published by the Free Software Foundation; either version
   9  * 2 of the Licence, or (at your option) any later version.
  10  */
  11
  12 #define pr_fmt(fmt) "PKCS7key: "fmt
  13 #include <linux/key.h>
  14 #include <linux/err.h>
  15 #include <linux/module.h>
  16 #include <linux/key-type.h>
  17 #include <crypto/pkcs7.h>
  18 #include <keys/user-type.h>
  19 #include <keys/system_keyring.h>
  20 #include "pkcs7_parser.h"
  21
  22 /*
  23  * Preparse a PKCS#7 wrapped and validated data blob.
  24  */
  25 static int pkcs7_preparse(struct key_preparsed_payload *prep)
  26 {
  27         struct pkcs7_message *pkcs7;
  28         const void *data, *saved_prep_data;
  29         size_t datalen, saved_prep_datalen;
  30         bool trusted;
  31         int ret;
  32
  33         kenter("");
  34
  35         saved_prep_data = prep->data;
  36         saved_prep_datalen = prep->datalen;
  37         pkcs7 = pkcs7_parse_message(saved_prep_data, saved_prep_datalen);
  38         if (IS_ERR(pkcs7)) {
  39                 ret = PTR_ERR(pkcs7);
  40                 goto error;
  41         }
  42
  43         ret = pkcs7_verify(pkcs7);
  44         if (ret < 0)
  45                 goto error_free;
  46
  47         ret = pkcs7_validate_trust(pkcs7, system_trusted_keyring, &trusted);
  48         if (ret < 0)
  49                 goto error_free;
  50         if (!trusted)
  51                 pr_warn("PKCS#7 message doesn't chain back to a trusted key\n");
  52
  53         ret = pkcs7_get_content_data(pkcs7, &data, &datalen, false);
  54         if (ret < 0)
  55                 goto error_free;
  56
  57         prep->data = data;
  58         prep->datalen = datalen;
  59         ret = user_preparse(prep);
  60         prep->data = saved_prep_data;
  61         prep->datalen = saved_prep_datalen;
  62
  63 error_free:
  64         pkcs7_free_message(pkcs7);
  65 error:
  66         kleave(" = %d", ret);
  67         return ret;
  68 }
  69
  70 /*
  71  * user defined keys take an arbitrary string as the description and an
  72  * arbitrary blob of data as the payload
  73  */
  74 static struct key_type key_type_pkcs7 = {
  75         .name                   = "pkcs7_test",
  76         .preparse               = pkcs7_preparse,
  77         .free_preparse          = user_free_preparse,
  78         .instantiate            = generic_key_instantiate,
  79         .revoke                 = user_revoke,
  80         .destroy                = user_destroy,
  81         .describe               = user_describe,
  82         .read                   = user_read,
  83 };
  84
  85 /*
  86  * Module stuff
  87  */
  88 static int __init pkcs7_key_init(void)
  89 {
  90         return register_key_type(&key_type_pkcs7);
  91 }
  92
  93 static void __exit pkcs7_key_cleanup(void)
  94 {
  95         unregister_key_type(&key_type_pkcs7);
  96 }
  97
  98 module_init(pkcs7_key_init);
  99 module_exit(pkcs7_key_cleanup);