// SPDX-License-Identifier: GPL-2.0+
  /*
   * Module signature checker
   *
   * Copyright (C) 2012 Red Hat, Inc. All Rights Reserved.
   * Written by David Howells (dhowells@redhat.com)
   */
  
  #include <linux/errno.h>
  #include <linux/printk.h>
  #include <linux/module_signature.h>
  #include <asm/byteorder.h>
  
  /**
   * mod_check_sig - check that the given signature is sane
   *
   * @ms:		Signature to check.
   * @file_len:	Size of the file to which @ms is appended.
   * @name:	What is being checked. Used for error messages.
   */
  int mod_check_sig(const struct module_signature *ms, size_t file_len,
  		  const char *name)
  {
  	if (be32_to_cpu(ms->sig_len) >= file_len - sizeof(*ms))
  		return -EBADMSG;
  
  	if (ms->id_type != PKEY_ID_PKCS7) {
  		pr_err("%s: Module is not signed with expected PKCS#7 message
  ",
  		       name);
  		return -ENOPKG;
  	}
  
  	if (ms->algo != 0 ||
  	    ms->hash != 0 ||
  	    ms->signer_len != 0 ||
  	    ms->key_id_len != 0 ||
  	    ms->__pad[0] != 0 ||
  	    ms->__pad[1] != 0 ||
  	    ms->__pad[2] != 0) {
  		pr_err("%s: PKCS#7 signature info has unexpected non-zero params
  ",
  		       name);
  		return -EBADMSG;
  	}
  
  	return 0;
  }