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/module.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)
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);
51