1// SPDX-License-Identifier: GPL-2.0+
2/*
3 * Module signature checker
4 *
5 * Copyright (C) 2012 Red Hat, Inc. All Rights Reserved.
6 * Written by David Howells (dhowells@redhat.com)
7 */
8
9#include <linux/errno.h>
10#include <linux/printk.h>
11#include <linux/module_signature.h>
12#include <asm/byteorder.h>
13
14/**
15 * mod_check_sig - check that the given signature is sane
16 *
17 * @ms:		Signature to check.
18 * @file_len:	Size of the file to which @ms is appended.
19 * @name:	What is being checked. Used for error messages.
20 */
21int mod_check_sig(const struct module_signature *ms, size_t file_len,
22		  const char *name)
23{
24	if (be32_to_cpu(ms->sig_len) >= file_len - sizeof(*ms))
25		return -EBADMSG;
26
27	if (ms->id_type != PKEY_ID_PKCS7) {
28		pr_err("%s: not signed with expected PKCS#7 message\n",
29		       name);
30		return -ENOPKG;
31	}
32
33	if (ms->algo != 0 ||
34	    ms->hash != 0 ||
35	    ms->signer_len != 0 ||
36	    ms->key_id_len != 0 ||
37	    ms->__pad[0] != 0 ||
38	    ms->__pad[1] != 0 ||
39	    ms->__pad[2] != 0) {
40		pr_err("%s: PKCS#7 signature info has unexpected non-zero params\n",
41		       name);
42		return -EBADMSG;
43	}
44
45	return 0;
46}
47