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/verification.h>
  17 #include <linux/key-type.h>
  18 #include <keys/user-type.h>
  19
  20 MODULE_LICENSE("GPL");
  21 MODULE_DESCRIPTION("PKCS#7 testing key type");
  22 MODULE_AUTHOR("Red Hat, Inc.");
  23
  24 static unsigned pkcs7_usage;
  25 module_param_named(usage, pkcs7_usage, uint, S_IWUSR | S_IRUGO);
  26 MODULE_PARM_DESC(pkcs7_usage,
  27                  "Usage to specify when verifying the PKCS#7 message");
  28
  29 /*
  30  * Retrieve the PKCS#7 message content.
  31  */
  32 static int pkcs7_view_content(void *ctx, const void *data, size_t len,
  33                               size_t asn1hdrlen)
  34 {
  35         struct key_preparsed_payload *prep = ctx;
  36         const void *saved_prep_data;
  37         size_t saved_prep_datalen;
  38         int ret;
  39
  40         saved_prep_data = prep->data;
  41         saved_prep_datalen = prep->datalen;
  42         prep->data = data;
  43         prep->datalen = len;
  44
  45         ret = user_preparse(prep);
  46
  47         prep->data = saved_prep_data;
  48         prep->datalen = saved_prep_datalen;
  49         return ret;
  50 }
  51
  52 /*
  53  * Preparse a PKCS#7 wrapped and validated data blob.
  54  */
  55 static int pkcs7_preparse(struct key_preparsed_payload *prep)
  56 {
  57         enum key_being_used_for usage = pkcs7_usage;
  58
  59         if (usage >= NR__KEY_BEING_USED_FOR) {
  60                 pr_err("Invalid usage type %d\n", usage);
  61                 return -EINVAL;
  62         }
  63
  64         return verify_pkcs7_signature(NULL, 0,
  65                                       prep->data, prep->datalen,
  66                                       (void *)1UL, usage,
  67                                       pkcs7_view_content, prep);
  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);