crypto/asymmetric_keys/signature.c

   1 /* Signature verification with an asymmetric key
   2  *
   3  * See Documentation/security/asymmetric-keys.txt
   4  *
   5  * Copyright (C) 2012 Red Hat, Inc. All Rights Reserved.
   6  * Written by David Howells (dhowells@redhat.com)
   7  *
   8  * This program is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU General Public Licence
  10  * as published by the Free Software Foundation; either version
  11  * 2 of the Licence, or (at your option) any later version.
  12  */
  13
  14 #define pr_fmt(fmt) "SIG: "fmt
  15 #include <keys/asymmetric-subtype.h>
  16 #include <linux/export.h>
  17 #include <linux/err.h>
  18 #include <crypto/public_key.h>
  19 #include "asymmetric_keys.h"
  20
  21 /**
  22  * verify_signature - Initiate the use of an asymmetric key to verify a signature
  23  * @key: The asymmetric key to verify against
  24  * @sig: The signature to check
  25  *
  26  * Returns 0 if successful or else an error.
  27  */
  28 int verify_signature(const struct key *key,
  29                      const struct public_key_signature *sig)
  30 {
  31         const struct asymmetric_key_subtype *subtype;
  32         int ret;
  33
  34         pr_devel("==>%s()\n", __func__);
  35
  36         if (key->type != &key_type_asymmetric)
  37                 return -EINVAL;
  38         subtype = asymmetric_key_subtype(key);
  39         if (!subtype ||
  40             !key->payload.data[0])
  41                 return -EINVAL;
  42         if (!subtype->verify_signature)
  43                 return -ENOTSUPP;
  44
  45         ret = subtype->verify_signature(key, sig);
  46
  47         pr_devel("<==%s() = %d\n", __func__, ret);
  48         return ret;
  49 }
  50 EXPORT_SYMBOL_GPL(verify_signature);