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/*========================== begin_copyright_notice ============================
Copyright (C) 2017-2021 Intel Corporation
SPDX-License-Identifier: MIT
============================= end_copyright_notice ===========================*/
#include "ElfReader.h"
#include "llvm/BinaryFormat/ELF.h"
#include <string.h>
namespace CLElfLib {
/******************************************************************************\
Constructor: RAIIElf::RAIIElf
\******************************************************************************/
RAIIElf::RAIIElf(CElfReader *pElf) : p(pElf) {}
/******************************************************************************\
Destructor: RAIIElf::RAIIElf
\******************************************************************************/
RAIIElf::~RAIIElf() {
if (p != NULL) {
CElfReader::Delete(p);
}
}
/******************************************************************************\
Constructor: CElfReader::CElfReader
\******************************************************************************/
CElfReader::CElfReader(const char *pElfBinary, const size_t elfBinarySize) {
m_pNameTable = NULL;
m_nameTableSize = 0;
m_pElfHeader = (SElfHeader *)pElfBinary;
m_pBinary = pElfBinary;
// get a pointer to the string table
if (m_pElfHeader) {
GetSectionData(m_pElfHeader->SectionNameTableIndex, m_pNameTable, m_nameTableSize);
}
}
/******************************************************************************\
Destructor: CElfReader::~CElfReader
\******************************************************************************/
CElfReader::~CElfReader() {}
/******************************************************************************\
Member Function: CElfReader::Create
\******************************************************************************/
CElfReader *CElfReader::Create(const char *pElfBinary, const size_t elfBinarySize) {
CElfReader *pNewReader = NULL;
if (IsValidElf(pElfBinary, elfBinarySize)) {
pNewReader = new CElfReader(pElfBinary, elfBinarySize);
}
return pNewReader;
}
/******************************************************************************\
Member Function: CElfReader::Delete
\******************************************************************************/
void CElfReader::Delete(CElfReader *&pElfReader) {
if (pElfReader) {
delete pElfReader;
pElfReader = NULL;
}
}
/******************************************************************************\
Member Function: IsValidElf64
Description: Determines if a binary is in the ELF64 format checks for
invalid offsets.
\******************************************************************************/
bool CElfReader::IsValidElf(const void *pBinary, const size_t binarySize) {
bool retVal = false;
SElfHeader *pElfHeader = NULL;
SElfSectionHeader *pSectionHeader = NULL;
size_t headerSize = sizeof(SElfHeader);
char *pNameTable = NULL;
char *pEnd = NULL;
size_t ourSize = 0;
size_t entrySize = 0;
size_t indexedSectionHeaderOffset = 0;
// validate header
if (pBinary && (binarySize >= headerSize)) {
// calculate a pointer to the end
pEnd = (char *)pBinary + binarySize;
pElfHeader = (SElfHeader *)pBinary;
if ((pElfHeader->Identity[ID_IDX_MAGIC0] == ELF_MAG0) && (pElfHeader->Identity[ID_IDX_MAGIC1] == ELF_MAG1) &&
(pElfHeader->Identity[ID_IDX_MAGIC2] == ELF_MAG2) && (pElfHeader->Identity[ID_IDX_MAGIC3] == ELF_MAG3) &&
(pElfHeader->Identity[ID_IDX_CLASS] == EH_CLASS_64 || pElfHeader->Identity[ID_IDX_CLASS] == EH_CLASS_32)) {
ourSize += pElfHeader->ElfHeaderSize;
retVal = true;
}
}
// validate sections
if (retVal == true) {
// get the section entry size
entrySize = pElfHeader->SectionHeaderEntrySize;
// get an offset to the name table
if (pElfHeader->SectionNameTableIndex < pElfHeader->NumSectionHeaderEntries) {
indexedSectionHeaderOffset =
(size_t)pElfHeader->SectionHeadersOffset + (pElfHeader->SectionNameTableIndex * entrySize);
if (((char *)pBinary + indexedSectionHeaderOffset) <= pEnd) {
SElfSectionHeader *pNameTableSectionHeader =
(SElfSectionHeader *)((char *)pBinary + indexedSectionHeaderOffset);
pNameTable = (char *)pBinary + pNameTableSectionHeader->DataOffset;
}
}
for (unsigned int i = 0; i < pElfHeader->NumSectionHeaderEntries; i++) {
indexedSectionHeaderOffset = (size_t)pElfHeader->SectionHeadersOffset + (i * entrySize);
// check section header offset
if (((char *)pBinary + indexedSectionHeaderOffset) > pEnd) {
retVal = false;
break;
}
pSectionHeader = (SElfSectionHeader *)((char *)pBinary + indexedSectionHeaderOffset);
// check section data
if (((char *)pBinary + pSectionHeader->DataOffset + pSectionHeader->DataSize) > pEnd) {
retVal = false;
break;
}
// check section name index
if ((pNameTable + pSectionHeader->Name) > pEnd) {
retVal = false;
break;
}
// tally up the sizes
ourSize += (size_t)pSectionHeader->DataSize;
ourSize += (size_t)entrySize;
}
// Learnt from NEO driver for zebin, does not need check size match
// if (ourSize != binarySize)
//{
// retVal = false;
//}
}
return retVal;
}
/******************************************************************************\
Member Function: GetElfHeader
Description: Returns a pointer to the requested section header
\******************************************************************************/
const SElfHeader *CElfReader::GetElfHeader() { return m_pElfHeader; }
/******************************************************************************\
Member Function: GetSectionHeader
Description: Returns a pointer to the requested section header
\******************************************************************************/
const SElfSectionHeader *CElfReader::GetSectionHeader(unsigned int sectionIndex) {
SElfSectionHeader *pSectionHeader = NULL;
size_t indexedSectionHeaderOffset = 0;
size_t entrySize = m_pElfHeader->SectionHeaderEntrySize;
if (sectionIndex < m_pElfHeader->NumSectionHeaderEntries) {
indexedSectionHeaderOffset = (size_t)m_pElfHeader->SectionHeadersOffset + (sectionIndex * entrySize);
pSectionHeader = (SElfSectionHeader *)((char *)m_pElfHeader + indexedSectionHeaderOffset);
}
return pSectionHeader;
}
/******************************************************************************\
Member Function: GetSectionHeader
Description: Returns a pointer to the requested section header
\******************************************************************************/
const SElfSectionHeader *CElfReader::GetSectionHeader(const char *pSectionName) {
const SElfSectionHeader *pSectionHeader = NULL;
const char *pCurrentName = NULL;
for (unsigned int i = 1; i < m_pElfHeader->NumSectionHeaderEntries; i++) {
pCurrentName = GetSectionName(i);
if (pSectionName && pCurrentName && (strcmp(pSectionName, pCurrentName) == 0)) {
pSectionHeader = GetSectionHeader(i);
break;
}
}
return pSectionHeader;
}
/******************************************************************************\
Member Function: GetSectionData
Description: Returns a pointer to and size of the requested section's
data
\******************************************************************************/
E_RETVAL CElfReader::GetSectionData(const unsigned int sectionIndex, char *&pData, size_t &dataSize) {
E_RETVAL retVal = FAILURE;
const SElfSectionHeader *pSectionHeader = GetSectionHeader(sectionIndex);
if (pSectionHeader) {
pData = (char *)m_pBinary + pSectionHeader->DataOffset;
dataSize = (size_t)pSectionHeader->DataSize;
retVal = SUCCESS;
}
return retVal;
}
/******************************************************************************\
Member Function: GetSectionData
Description: Returns a pointer to and size of the requested section's
data
\******************************************************************************/
E_RETVAL CElfReader::GetSectionData(const char *pName, char *&pData, size_t &dataSize) {
E_RETVAL retVal = FAILURE;
const char *pSectionName = NULL;
for (unsigned int i = 1; i < m_pElfHeader->NumSectionHeaderEntries; i++) {
pSectionName = GetSectionName(i);
if (pSectionName && (strcmp(pName, pSectionName) == 0)) {
GetSectionData(i, pData, dataSize);
retVal = SUCCESS;
break;
}
}
return retVal;
}
/******************************************************************************\
Member Function: GetSectionName
Description: Returns a pointer to a NULL terminated string
\******************************************************************************/
const char *CElfReader::GetSectionName(unsigned int sectionIndex) {
char *pName = NULL;
const SElfSectionHeader *pSectionHeader = GetSectionHeader(sectionIndex);
if (pSectionHeader) {
pName = m_pNameTable + pSectionHeader->Name;
}
return pName;
}
} // namespace CLElfLib
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