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AbstractElfAccessor.h
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AbstractElfAccessor.h
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#pragma once
#include "Range.h"
#include "scrub.h"
#include <string>
#include <vector>
#include <stdexcept>
class AbstractElfAccessor
{
// Block size should be multiple of native page size
static constexpr ssize_t BLOCK_SIZE = 0x1000;
public:
struct Patch{
size_t start;
size_t size;
std::string content;
// Convert to a string for transfer over the network
std::string serialize()const
{
return std::to_string(start)+" "+std::to_string(size)+" "+content;
}
// Apply a patch using a custom applicator
// in chunks of `chunk_size` bytes
template<class Chunk>
void apply(auto&& applicator) const
{
const auto chunk_size = sizeof(Chunk);
const auto patch_end = start + size;
if(chunk_size < 1 || chunk_size > sizeof(uint64_t))
throw std::invalid_argument("Invalid chunk size");
for(unsigned i=start;i<patch_end;i+=chunk_size)
{
Chunk chunk = 0;
for(unsigned j=0;j<chunk_size;j++)
{
Chunk new_byte = 0;
const size_t index = i+j-start;
if(index < size)
new_byte = static_cast<unsigned char>(content.at(index));
chunk += (Chunk)(new_byte) << ((Chunk)(8)*j);
}
applicator(i, chunk);
}
}
};
using PatchList = std::vector<Patch>;
// Fetch patches within block containing `address`
// `Address` may be any address inside a valid block
// `Patches` is filled with patches for the block
virtual void fetchPatches(const void* address, PatchList& patches) = 0;
// Returns address of first block
virtual void* memoryStart() = 0;
// Returns first address of executable memory
// (not block aligned)
virtual void* entryPoint() = 0;
// Returns total size of relevant regions
// (Regions that merchant transfers and agent protects)
virtual size_t memorySize() = 0;
// Get the clipped version of elf file
virtual std::string getBlankElf(std::vector<Range>& ranges) = 0;
virtual std::string getExpandedElf()
{
std::vector<Range> ranges;
const auto contents = getBlankElf(ranges);
return expandScrubbedElf(contents, ranges);
}
void* alignToBlockStart(const void* address) const noexcept
{
uintptr_t improved = (uintptr_t) address;
improved &= ~(getBlockSize()-1);
return (void*)improved;
}
uintptr_t alignToBlockStart(const uintptr_t address) const noexcept
{
return (uintptr_t)alignToBlockStart((void*)address);
}
size_t getBlockSize() const noexcept
{
return BLOCK_SIZE;
}
};