libkern/stack_protector.c

   1 /*
   2  * Copyright (c) 2008 Apple Computer, Inc. All rights reserved.
   3  *
   4  * %Begin-Header%
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, and the entire permission notice in its entirety,
  10  *    including the disclaimer of warranties.
  11  * 2. Redistributions in binary form must reproduce the above copyright
  12  *    notice, this list of conditions and the following disclaimer in the
  13  *    documentation and/or other materials provided with the distribution.
  14  * 3. The name of the author may not be used to endorse or promote
  15  *    products derived from this software without specific prior
  16  *    written permission.
  17  *
  18  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
  19  * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  20  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE, ALL OF
  21  * WHICH ARE HEREBY DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR BE
  22  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  23  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
  24  * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
  25  * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
  26  * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  27  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE
  28  * USE OF THIS SOFTWARE, EVEN IF NOT ADVISED OF THE POSSIBILITY OF SUCH
  29  * DAMAGE.
  30  * %End-Header%
  31  */
  32
  33 /*******************************************************************************
  34 * NOTE: This implementation of the stack check routines required by the GCC
  35 * -fstack-protector flag is only safe for kernel extensions.
  36 *******************************************************************************/
  37
  38 #include <sys/types.h>
  39 #include <sys/random.h>
  40 #include <kern/debug.h>
  41
  42 long __stack_chk_guard[8];
  43 void __stack_chk_fail(void);
  44
  45 static void __guard_setup(void) __attribute__((constructor));
  46
  47 static void
  48 __guard_setup(void)
  49 {
  50     /* Cannot report failure.  */
  51     read_random(__stack_chk_guard, sizeof(__stack_chk_guard));
  52 }
  53
  54 void
  55 __stack_chk_fail(void)
  56 {
  57     panic("Kernel stack memory corruption detected");
  58 }
  59