// 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)
  ", __func__, modlen);
  
  	if (modlen <= sizeof(ms))
  		return -EBADMSG;
  
  	memcpy(&ms, mod + (modlen - sizeof(ms)), sizeof(ms));
  
  	ret = mod_check_sig(&ms, modlen, info->name);
  	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);
  }