--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/libvtv/vtv_fail.cc	Fri Oct 27 22:46:09 2017 +0900
@@ -0,0 +1,238 @@
+/* Copyright (C) 2012-2017 Free Software Foundation, Inc.
+
+ This file is part of GCC.
+
+ GCC is free software; you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation; either version 3, or (at your option)
+ any later version.
+
+ GCC is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ GNU General Public License for more details.
+
+ Under Section 7 of GPL version 3, you are granted additional
+ permissions described in the GCC Runtime Library Exception, version
+ 3.1, as published by the Free Software Foundation.
+
+ You should have received a copy of the GNU General Public License and
+ a copy of the GCC Runtime Library Exception along with this program;
+ see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
+ <http://www.gnu.org/licenses/>.  */
+
+/* This file is part of the vtable security feature implementation.
+   The vtable security feature is designed to detect when a virtual
+   call is about to be made through an invalid vtable pointer
+   (possibly due to data corruption or malicious attacks).
+
+   This file also contains the failure functions that get called when
+   a vtable pointer is not found in the data set.  Two particularly
+   important functions are __vtv_verify_fail and __vtv_really_fail.
+   They are both externally visible.  __vtv_verify_fail is defined in
+   such a way that it can be replaced by a programmer, if desired.  It
+   is the function that __VLTVerifyVtablePointer calls if it can't
+   find the pointer in the data set.  Allowing the programmer to
+   overwrite this function means that he/she can do some alternate
+   verification, including NOT failing in certain specific cases, if
+   desired.  This may be the case if the programmer has to deal wtih
+   unverified third party software, for example.  __vtv_really_fail is
+   available for the programmer to call from his version of
+   __vtv_verify_fail, if he decides the failure is real.
+
+*/
+
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+
+#if !defined (__CYGWIN__) && !defined (__MINGW32__)
+#include <execinfo.h>
+#endif
+
+#include <unistd.h>
+
+#include "vtv_utils.h"
+#include "vtv_fail.h"
+
+/* This is used to disable aborts for debugging purposes.  */
+bool vtv_no_abort = false;
+
+
+extern "C" {
+
+  /* __fortify_fail is a function in glibc that calls __libc_message,
+     causing it to print out a program termination error message
+     (including the name of the binary being terminated), a stack
+     trace where the error occurred, and a memory map dump.  Ideally
+     we would have called __libc_message directly, but that function
+     does not appear to be accessible to functions outside glibc,
+     whereas __fortify_fail is.  We call __fortify_fail from
+     __vtv_really_fail.  We looked at calling __libc_fatal, which is
+     externally accessible, but it does not do the back trace and
+     memory dump.  */
+
+  extern void __fortify_fail (const char *) __attribute__((noreturn));
+
+} /* extern "C" */
+
+const unsigned long SET_HANDLE_HANDLE_BIT = 0x2;
+
+/* Instantiate the template classes (in vtv_set.h) for our particular
+   hash table needs.  */
+typedef void * vtv_set_handle;
+typedef vtv_set_handle * vtv_set_handle_handle; 
+
+static int vtv_failures_log_fd = -1;
+
+/* Open error logging file, if not already open, and write vtable
+   verification failure messages (LOG_MSG) to the log file.  Also
+   generate a backtrace in the log file, if GENERATE_BACKTRACE is
+   set.  */
+
+static void
+log_error_message (const char *log_msg, bool generate_backtrace)
+{
+  if (vtv_failures_log_fd == -1)
+    vtv_failures_log_fd = vtv_open_log ("vtable_verification_failures.log");
+
+  if (vtv_failures_log_fd == -1)
+    return;
+
+  vtv_add_to_log (vtv_failures_log_fd, "%s", log_msg);
+
+  if (generate_backtrace)
+    {
+#define STACK_DEPTH 20
+      void *callers[STACK_DEPTH];
+#if !defined (__CYGWIN__) && !defined (__MINGW32__)
+      int actual_depth = backtrace (callers, STACK_DEPTH);
+      backtrace_symbols_fd (callers, actual_depth, vtv_failures_log_fd);
+#endif
+    }
+}
+
+/* In the case where a vtable map variable is the only instance of the
+   variable we have seen, it points directly to the set of valid
+   vtable pointers.  All subsequent instances of the 'same' vtable map
+   variable point to the first vtable map variable.  This function,
+   given a vtable map variable PTR, checks a bit to see whether it's
+   pointing directly to the data set or to the first vtable map
+   variable.  */
+
+static inline bool
+is_set_handle_handle (void * ptr)
+{
+  return ((unsigned long) ptr & SET_HANDLE_HANDLE_BIT)
+                                                      == SET_HANDLE_HANDLE_BIT;
+}
+
+/* Returns the actual pointer value of a vtable map variable, PTR (see
+   comments for is_set_handle_handle for more details).  */
+
+static inline vtv_set_handle * 
+ptr_from_set_handle_handle (void * ptr)
+{
+  return (vtv_set_handle *) ((unsigned long) ptr & ~SET_HANDLE_HANDLE_BIT);
+}
+
+/* Given a vtable map variable, PTR, this function sets the bit that
+   says this is the second (or later) instance of a vtable map
+   variable.  */
+
+static inline vtv_set_handle_handle
+set_handle_handle (vtv_set_handle * ptr)
+{
+  return (vtv_set_handle_handle) ((unsigned long) ptr | SET_HANDLE_HANDLE_BIT);
+}
+
+/* This function is called from __VLTVerifyVtablePointerDebug; it
+   sends as much debugging information as it can to the error log
+   file, then calls __vtv_verify_fail.  SET_HANDLE_PTR is the pointer
+   to the set of valid vtable pointers, VTBL_PTR is the pointer that
+   was not found in the set, and DEBUG_MSG is the message to be
+   written to the log file before failing. n */
+
+void
+__vtv_verify_fail_debug (void **set_handle_ptr, const void *vtbl_ptr, 
+                         const char *debug_msg)
+{
+  log_error_message (debug_msg, false);
+
+  /* Call the public interface in case it has been overwritten by
+     user.  */
+  __vtv_verify_fail (set_handle_ptr, vtbl_ptr);
+
+  log_error_message ("Returned from __vtv_verify_fail."
+                     " Secondary verification succeeded.\n", false);
+}
+
+/* This function calls __fortify_fail with a FAILURE_MSG and then
+   calls abort.  */
+
+void
+__vtv_really_fail (const char *failure_msg)
+{
+  __fortify_fail (failure_msg);
+
+  /* We should never get this far; __fortify_fail calls __libc_message
+     which prints out a back trace and a memory dump and then is
+     supposed to call abort, but let's play it safe anyway and call abort
+     ourselves.  */
+  abort ();
+}
+
+/* This function takes an error MSG, a vtable map variable
+   (DATA_SET_PTR) and a vtable pointer (VTBL_PTR).  It is called when
+   an attempt to verify VTBL_PTR with the set pointed to by
+   DATA_SET_PTR failed.  It outputs a failure message with the
+   addresses involved, and calls __vtv_really_fail.  */
+
+static void
+vtv_fail (const char *msg, void **data_set_ptr, const void *vtbl_ptr)
+{
+  char buffer[128];
+  int buf_len;
+  const char *format_str =
+                 "*** Unable to verify vtable pointer (%p) in set (%p) *** \n";
+
+  snprintf (buffer, sizeof (buffer), format_str, vtbl_ptr,
+            is_set_handle_handle(*data_set_ptr) ?
+              ptr_from_set_handle_handle (*data_set_ptr) :
+	      *data_set_ptr);
+  buf_len = strlen (buffer);
+  /*  Send this to to stderr.  */
+  write (2, buffer, buf_len);
+
+  if (!vtv_no_abort)
+    __vtv_really_fail (msg);
+}
+
+/* Send information about what we were trying to do when verification
+   failed to the error log, then call vtv_fail.  This function can be
+   overwritten/replaced by the user, to implement a secondary
+   verification function instead.  DATA_SET_PTR is the vtable map
+   variable used for the failed verification, and VTBL_PTR is the
+   vtable pointer that was not found in the set.  */
+
+void
+__vtv_verify_fail (void **data_set_ptr, const void *vtbl_ptr)
+{
+  char log_msg[256];
+  snprintf (log_msg, sizeof (log_msg), "Looking for vtable %p in set %p.\n",
+            vtbl_ptr,
+            is_set_handle_handle (*data_set_ptr) ?
+              ptr_from_set_handle_handle (*data_set_ptr) :
+              *data_set_ptr);
+  log_error_message (log_msg, false);
+
+  const char *format_str =
+            "*** Unable to verify vtable pointer (%p) in set (%p) *** \n";
+  snprintf (log_msg, sizeof (log_msg), format_str, vtbl_ptr, *data_set_ptr);
+  log_error_message (log_msg, false);
+  log_error_message ("  Backtrace: \n", true);
+
+  const char *fail_msg = "Potential vtable pointer corruption detected!!\n";
+  vtv_fail (fail_msg, data_set_ptr, vtbl_ptr);
+}
+