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