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/*
* Copyright (C) 2016 The Android Open Source Project
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#pragma once
#include "linker.h"
#include "linker_debug.h"
#include <algorithm>
#include "private/CFIShadow.h"
// This class keeps the contents of CFI shadow up-to-date with the current set of loaded libraries.
// See the comment in CFIShadow.h for more context.
// See documentation in http://clang.llvm.org/docs/ControlFlowIntegrityDesign.html#shared-library-support.
//
// Shadow is mapped and initialized lazily as soon as the first CFI-enabled DSO is loaded.
// It is updated after any library is loaded (but before any constructors are ran), and
// before any library is unloaded.
class CFIShadowWriter : private CFIShadow {
// Returns pointer to the shadow element for an address.
uint16_t* MemToShadow(uintptr_t x) {
return reinterpret_cast<uint16_t*>(*shadow_start + MemToShadowOffset(x));
}
// Update shadow for the address range to the given constant value.
void AddConstant(uintptr_t begin, uintptr_t end, uint16_t v);
// Update shadow for the address range to kUncheckedShadow.
void AddUnchecked(uintptr_t begin, uintptr_t end);
// Update shadow for the address range to kInvalidShadow.
void AddInvalid(uintptr_t begin, uintptr_t end);
// Update shadow for the address range to the given __cfi_check value.
void Add(uintptr_t begin, uintptr_t end, uintptr_t cfi_check);
// Add a DSO to CFI shadow.
bool AddLibrary(soinfo* si);
// Map CFI shadow.
uintptr_t MapShadow();
// Initialize CFI shadow and update its contents for everything in solist if any loaded library is
// CFI-enabled. If new_si != nullptr, do an incremental check by looking only at new_si; otherwise
// look at the entire solist.
bool MaybeInit(soinfo *new_si, soinfo *solist);
// Set a human readable name for the entire shadow region.
void FixupVmaName();
// Pass the pointer to the mapped shadow region to libdl. Must only be called once.
// Flips shadow_start to a non-nullptr value.
bool NotifyLibDl(soinfo *solist, uintptr_t p);
// Pointer to the shadow start address.
uintptr_t *shadow_start;
bool initial_link_done;
public:
// Update shadow after loading a DSO.
// This function will initialize the shadow if it sees a CFI-enabled DSO for the first time.
// In that case it will retroactively update shadow for all previously loaded DSOs. "solist" is a
// pointer to the global list.
// This function must be called before any user code has observed the newly loaded DSO.
bool AfterLoad(soinfo* si, soinfo *solist);
// Update shadow before unloading a DSO.
void BeforeUnload(soinfo* si);
// This is called as soon as the initial set of libraries is linked.
bool InitialLinkDone(soinfo *solist);
// Handle failure to locate __cfi_check for a target address.
static void CfiFail(uint64_t CallSiteTypeId, void* Ptr, void* DiagData, void *caller_pc);
};
CFIShadowWriter* get_cfi_shadow();