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 */
21 int 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
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