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/key-type.h>
  16 #include <crypto/pkcs7.h>
  17 #include <keys/user-type.h>
  18 #include <keys/system_keyring.h>
  19 #include "pkcs7_parser.h"
  20
  21 /*
  22  * Preparse a PKCS#7 wrapped and validated data blob.
  23  */
  24 static int pkcs7_preparse(struct key_preparsed_payload *prep)
  25 {
  26         struct pkcs7_message *pkcs7;
  27         const void *data, *saved_prep_data;
  28         size_t datalen, saved_prep_datalen;
  29         bool trusted;
  30         int ret;
  31
  32         kenter("");
  33
  34         saved_prep_data = prep->data;
  35         saved_prep_datalen = prep->datalen;
  36         pkcs7 = pkcs7_parse_message(saved_prep_data, saved_prep_datalen);
  37         if (IS_ERR(pkcs7)) {
  38                 ret = PTR_ERR(pkcs7);
  39                 goto error;
  40         }
  41
  42         ret = pkcs7_verify(pkcs7);
  43         if (ret < 0)
  44                 goto error_free;
  45
  46         ret = pkcs7_validate_trust(pkcs7, system_trusted_keyring, &trusted);
  47         if (ret < 0)
  48                 goto error_free;
  49         if (!trusted)
  50                 pr_warn("PKCS#7 message doesn't chain back to a trusted key\n");
  51
  52         ret = pkcs7_get_content_data(pkcs7, &data, &datalen, false);
  53         if (ret < 0)
  54                 goto error_free;
  55
  56         prep->data = data;
  57         prep->datalen = datalen;
  58         ret = user_preparse(prep);
  59         prep->data = saved_prep_data;
  60         prep->datalen = saved_prep_datalen;
  61
  62 error_free:
  63         pkcs7_free_message(pkcs7);
  64 error:
  65         kleave(" = %d", ret);
  66         return ret;
  67 }
  68
  69 /*
  70  * user defined keys take an arbitrary string as the description and an
  71  * arbitrary blob of data as the payload
  72  */
  73 static struct key_type key_type_pkcs7 = {
  74         .name                   = "pkcs7_test",
  75         .preparse               = pkcs7_preparse,
  76         .free_preparse          = user_free_preparse,
  77         .instantiate            = generic_key_instantiate,
  78         .revoke                 = user_revoke,
  79         .destroy                = user_destroy,
  80         .describe               = user_describe,
  81         .read                   = user_read,
  82 };
  83
  84 /*
  85  * Module stuff
  86  */
  87 static int __init pkcs7_key_init(void)
  88 {
  89         return register_key_type(&key_type_pkcs7);
  90 }
  91
  92 static void __exit pkcs7_key_cleanup(void)
  93 {
  94         unregister_key_type(&key_type_pkcs7);
  95 }
  96
  97 module_init(pkcs7_key_init);
  98 module_exit(pkcs7_key_cleanup);