зеркало из https://github.com/mozilla/gecko-dev.git
75 строки
2.7 KiB
C++
75 строки
2.7 KiB
C++
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/* -*- Mode: C++; tab-width: 40; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#include <windows.h>
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#include <winternl.h>
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#include <io.h>
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#include <intrin.h>
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#include <setjmp.h>
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#include "WindowsCFGStatus.h"
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// Inspired by https://github.com/trailofbits/cfg-showcase/blob/master/cfg_icall.cpp
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jmp_buf env;
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#pragma optimize("", off )
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void not_entry_point() {
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__nop(); __nop(); __nop(); __nop(); __nop(); __nop(); __nop(); __nop();
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__nop(); __nop(); __nop(); __nop(); __nop(); __nop(); __nop(); __nop();
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__nop(); __nop(); __nop(); __nop(); __nop(); __nop(); __nop(); __nop();
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__nop(); __nop(); __nop(); __nop(); __nop(); __nop(); __nop(); __nop();
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__nop(); __nop(); __nop(); __nop(); __nop(); __nop(); __nop(); __nop();
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__nop(); __nop(); __nop(); __nop(); __nop(); __nop(); __nop(); __nop();
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__nop(); __nop(); __nop(); __nop(); __nop(); __nop(); __nop(); __nop();
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__nop(); __nop(); __nop(); __nop(); __nop(); __nop(); __nop(); __nop();
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__nop(); __nop(); __nop(); __nop(); __nop(); __nop(); __nop(); __nop();
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__nop(); __nop(); __nop(); __nop(); __nop(); __nop(); __nop(); __nop();
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__nop(); __nop(); __nop(); __nop(); __nop(); __nop(); __nop(); __nop();
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__nop(); __nop(); __nop(); __nop(); __nop(); __nop(); __nop(); __nop();
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__nop(); __nop(); __nop(); __nop(); __nop(); __nop(); __nop(); __nop();
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longjmp(env, 1);
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return;
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}
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#pragma optimize("", on )
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typedef void (*fn_ptr)();
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/*
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* Tests for Microsoft's Control Flow Guard compiler security feature.
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* This function will crash if CFG is enabled, and return false if it is
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* not enabled.
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*
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* CFG protects indirect function calls and ensures they call a valid entry
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* point. We create a function pointer that calls an invalid entry point.
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* That invalid entry point is a nop sled.
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*
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* Jumping into the nop sled skips the preamble that a function normally
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* performs, so if we hit the return (ret) we would mess up the stack.
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* To 'return' from the function safely we jump back to our original
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* function - no preamble and no return.
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*
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* We use setjmp/longjmp because inline asm instructions aren't supported
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* in x64 by MSVC.
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*/
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MFBT_API bool
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CFG_DisabledOrCrash()
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{
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// setjmp returns 0 on the initial call and whatever value is given
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// to longjmp (here it is 1) when it is jumped back to.
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int val = setjmp(env);
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if (val == 0) {
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fn_ptr slide_to_the_left = (fn_ptr)((uintptr_t)(not_entry_point) + 0x20);
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// If CFG is enabled, we're going to crash on the next line
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slide_to_the_left();
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}
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return false;
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}
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