93 lines
2.5 KiB
C
93 lines
2.5 KiB
C
/***
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*seccinit.c - initialize the global buffer overrun security cookie
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*
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* Copyright (c) 2000-2001, Microsoft Corporation. All rights reserved.
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*
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*Purpose:
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* Define __security_init_cookie, which is called at startup to initialize
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* the global buffer overrun security cookie used by the /GS compile flag.
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*
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* NOTE: The ATLMINCRT library includes a version of this file. If any
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* changes are made here, they should be duplicated in the ATL version.
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*
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*Revision History:
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* 01-24-00 PML Created.
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* 09-16-00 PML Make sure cookie never initialized to zero (vs7#162619)
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* 09-20-00 PML Use a better cookie initialization (vs7#165188)
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*
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*******************************************************************************/
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#include <internal.h>
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#include <windows.h>
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/*
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* The global security cookie. This name is known to the compiler.
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*/
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extern DWORD_PTR __security_cookie;
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/*
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* Union to facilitate converting from FILETIME to unsigned __int64
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*/
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typedef union {
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unsigned __int64 ft_scalar;
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FILETIME ft_struct;
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} FT;
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/***
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*__security_init_cookie(cookie) - init buffer overrun security cookie.
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*
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*Purpose:
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* Initialize the global buffer overrun security cookie which is used by
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* the /GS compile switch to detect overwrites to local array variables
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* the potentially corrupt the return address. This routine is called
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* at EXE/DLL startup.
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*
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*Entry:
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*
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*Exit:
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*
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*Exceptions:
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*
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*******************************************************************************/
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void __cdecl __security_init_cookie(void)
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{
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DWORD_PTR cookie;
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FT systime;
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LARGE_INTEGER perfctr;
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/*
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* Initialize the global cookie with an unpredictable value which is
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* different for each module in a process. Combine a number of sources
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* of randomness.
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*/
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GetSystemTimeAsFileTime(&systime.ft_struct);
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#if !defined(_WIN64)
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cookie = systime.ft_struct.dwLowDateTime;
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cookie ^= systime.ft_struct.dwHighDateTime;
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#else
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cookie = systime.ft_scalar;
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#endif
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cookie ^= GetCurrentProcessId();
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cookie ^= GetCurrentThreadId();
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cookie ^= GetTickCount();
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QueryPerformanceCounter(&perfctr);
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#if !defined(_WIN64)
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cookie ^= perfctr.LowPart;
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cookie ^= perfctr.HighPart;
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#else
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cookie ^= perfctr.QuadPart;
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#endif
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/*
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* Make sure the global cookie is never initialized to zero, since in that
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* case an overrun which sets the local cookie and return address to the
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* same value would go undetected.
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*/
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__security_cookie = cookie ? cookie : 0xBB40E64E;
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}
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