mirror of
https://github.com/mirror/processhacker
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wj32
7bd28e4357
git-svn-id: svn://svn.code.sf.net/p/processhacker/code@2304 21ef857c-d57f-4fe0-8362-d861dc6d29cd
97 lines
2.7 KiB
C
97 lines
2.7 KiB
C
/*
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* Process Hacker Library -
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* hooks
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*
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* Copyright (C) 2009 wj32
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*
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* This file is part of Process Hacker.
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*
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* Process Hacker is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* Process Hacker is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with Process Hacker. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include "hook.h"
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VOID PHAPI PhInitializeHook(
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PPH_HOOK Hook,
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PVOID Function,
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PVOID Target
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)
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{
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memset(Hook, 0, sizeof(PH_HOOK));
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Hook->Function = Function;
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Hook->Target = Target;
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}
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NTSTATUS PHAPI PhHook(
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PPH_HOOK Hook
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)
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{
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NTSTATUS status = STATUS_SUCCESS;
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ULONG oldProtection;
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PCHAR function;
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/* Change the page protection of the target page so we can write to it. */
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if (!VirtualProtect(Hook->Function, 5, PAGE_EXECUTE_READWRITE, &oldProtection))
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return STATUS_ACCESS_VIOLATION;
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__try
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{
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function = (PCHAR)Hook->Function;
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/* Copy the original five bytes for unhooking. */
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memcpy(Hook->Bytes, function, 5);
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/* Hook the function by writing a jump instruction. */
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Hook->Hooked = TRUE;
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/* jmp Target */
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*function = 0xe9;
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*(PULONG_PTR)(function + 1) = (ULONG_PTR)Hook->Target - (ULONG_PTR)Hook->Function - 5;
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}
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__except (EXCEPTION_EXECUTE_HANDLER)
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{
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status = GetExceptionCode();
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}
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/* Restore the old page protection. */
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VirtualProtect(Hook->Function, 5, oldProtection, NULL);
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return status;
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}
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NTSTATUS PHAPI PhUnhook(
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PPH_HOOK Hook
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)
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{
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NTSTATUS status = STATUS_SUCCESS;
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ULONG oldProtection;
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/* Change the page protection of the target page so we can write to it. */
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if (!VirtualProtect(Hook->Function, 5, PAGE_EXECUTE_READWRITE, &oldProtection))
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return STATUS_ACCESS_VIOLATION;
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__try
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{
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/* Unpatch the function by restoring the original first 5 bytes. */
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memcpy(Hook->Function, Hook->Bytes, 5);
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Hook->Hooked = FALSE;
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}
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__except (EXCEPTION_EXECUTE_HANDLER)
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{
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status = GetExceptionCode();
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}
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/* Restore the old page protection. */
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VirtualProtect(Hook->Function, 5, oldProtection, NULL);
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return status;
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}
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