kernel/module_signing.c

// SPDX-License-Identifier: GPL-2.0-or-later
/* Module signature checker
 *
 * Copyright (C) 2012 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells (dhowells@redhat.com)
 */

#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/module.h>
#include <linux/module_signature.h>
#include <linux/string.h>
#include <linux/verification.h>
#include <crypto/public_key.h>
#include "module-internal.h"

/*
 * Verify the signature on a module.
 */
int mod_verify_sig(const void *mod, struct load_info *info)
{
	struct module_signature ms;
	size_t sig_len, modlen = info->len;
	int ret;

	pr_devel("==>%s(,%zu)\n", __func__, modlen);

	if (modlen <= sizeof(ms))
		return -EBADMSG;

	memcpy(&ms, mod + (modlen - sizeof(ms)), sizeof(ms));

	ret = mod_check_sig(&ms, modlen, "module");
	if (ret)
		return ret;

	sig_len = be32_to_cpu(ms.sig_len);
	modlen -= sig_len + sizeof(ms);
	info->len = modlen;

	return verify_pkcs7_signature(mod, modlen, mod + modlen, sig_len,
				      VERIFY_USE_SECONDARY_KEYRING,
				      VERIFYING_MODULE_SIGNATURE,
				      NULL, NULL);
}