mirror of
https://github.com/rene-dev/stmbl.git
synced 2024-12-25 10:02:18 +00:00
319 lines
12 KiB
Python
319 lines
12 KiB
Python
|
#!/usr/bin/env python
|
||
|
|
import struct
|
||
|
|
|
||
|
|
# ELF object file reader
|
||
|
|
# (C) 2003 cliechti@gmx.net
|
||
|
|
# Python license
|
||
|
|
|
||
|
|
# size alignment
|
||
|
|
# Elf32_Addr 4 4 Unsigned program address
|
||
|
|
# Elf32_Half 2 2 Unsigned medium integer
|
||
|
|
# Elf32_Off 4 4 Unsigned file offset
|
||
|
|
# Elf32_Sword 4 4 Signed large integer
|
||
|
|
# Elf32_Word 4 4 Unsigned large integer
|
||
|
|
# unsignedchar 1 1 Unsigned small integer
|
||
|
|
|
||
|
|
#define EI_NIDENT 16
|
||
|
|
#~ typedef struct{
|
||
|
|
#~ unsigned char e_ident[EI_NIDENT];
|
||
|
|
#~ Elf32_Half e_type;
|
||
|
|
#~ Elf32_Half e_machine;
|
||
|
|
#~ Elf32_Word e_version;
|
||
|
|
#~ Elf32_Addr e_entry;
|
||
|
|
#~ Elf32_Off e_phoff;
|
||
|
|
#~ Elf32_Off e_shoff;
|
||
|
|
#~ Elf32_Word e_flags;
|
||
|
|
#~ Elf32_Half e_ehsize;
|
||
|
|
#~ Elf32_Half e_phentsize;
|
||
|
|
#~ Elf32_Half e_phnum;
|
||
|
|
#~ Elf32_Half e_shentsize;
|
||
|
|
#~ Elf32_Half e_shnum;
|
||
|
|
#~ Elf32_Half e_shstrndx;
|
||
|
|
#~ } Elf32_Ehdr;
|
||
|
|
|
||
|
|
|
||
|
|
#Section Header
|
||
|
|
#~ typedef struct {
|
||
|
|
#~ Elf32_Word sh_name;
|
||
|
|
#~ Elf32_Word sh_type;
|
||
|
|
#~ Elf32_Word sh_flags;
|
||
|
|
#~ Elf32_Addr sh_addr;
|
||
|
|
#~ Elf32_Off sh_offset;
|
||
|
|
#~ Elf32_Word sh_size;
|
||
|
|
#~ Elf32_Word sh_link;
|
||
|
|
#~ Elf32_Word sh_info;
|
||
|
|
#~ Elf32_Word sh_addralign;
|
||
|
|
#~ Elf32_Word sh_entsize;
|
||
|
|
#~ } Elf32_Shdr;
|
||
|
|
|
||
|
|
#~ typedef struct {
|
||
|
|
#~ Elf32_Word p_type;
|
||
|
|
#~ Elf32_Off p_offset;
|
||
|
|
#~ Elf32_Addr p_vaddr;
|
||
|
|
#~ Elf32_Addr p_paddr;
|
||
|
|
#~ Elf32_Word p_filesz;
|
||
|
|
#~ Elf32_Word p_memsz;
|
||
|
|
#~ Elf32_Word p_flags;
|
||
|
|
#~ Elf32_Word p_align;
|
||
|
|
#~ } Elf32_Phdr;
|
||
|
|
|
||
|
|
|
||
|
|
class ELFException(Exception): pass
|
||
|
|
|
||
|
|
class ELFSection:
|
||
|
|
"""read and store a section"""
|
||
|
|
Elf32_Shdr = "<IIIIIIIIII" #header format
|
||
|
|
|
||
|
|
#section types
|
||
|
|
SHT_NULL = 0
|
||
|
|
SHT_PROGBITS = 1
|
||
|
|
SHT_SYMTAB = 2
|
||
|
|
SHT_STRTAB = 3
|
||
|
|
SHT_RELA = 4
|
||
|
|
SHT_HASH = 5
|
||
|
|
SHT_DYNAMIC = 6
|
||
|
|
SHT_NOTE = 7
|
||
|
|
SHT_NOBITS = 8
|
||
|
|
SHT_REL = 9
|
||
|
|
SHT_SHLIB = 10
|
||
|
|
SHT_DYNSYM = 11
|
||
|
|
SHT_LOPROC = 0x70000000L
|
||
|
|
SHT_HIPROC = 0x7fffffffL
|
||
|
|
SHT_LOUSER = 0x80000000L
|
||
|
|
SHT_HIUSER = 0xffffffffL
|
||
|
|
#section attribute flags
|
||
|
|
SHF_WRITE = 0x1
|
||
|
|
SHF_ALLOC = 0x2
|
||
|
|
SHF_EXECINSTR = 0x4
|
||
|
|
SHF_MASKPROC = 0xf0000000L
|
||
|
|
|
||
|
|
def __init__(self):
|
||
|
|
"""creat a new empty section object"""
|
||
|
|
(self.sh_name, self.sh_type, self.sh_flags, self.sh_addr,
|
||
|
|
self.sh_offset, self.sh_size, self.sh_link, self.sh_info,
|
||
|
|
self.sh_addralign, self.sh_entsize) = [0]*10
|
||
|
|
self.name = None
|
||
|
|
self.data = None
|
||
|
|
self.lma = None
|
||
|
|
|
||
|
|
def fromString(self, s):
|
||
|
|
"""get section header from string"""
|
||
|
|
(self.sh_name, self.sh_type, self.sh_flags, self.sh_addr,
|
||
|
|
self.sh_offset, self.sh_size, self.sh_link, self.sh_info,
|
||
|
|
self.sh_addralign, self.sh_entsize) = struct.unpack(self.Elf32_Shdr, s)
|
||
|
|
|
||
|
|
def __str__(self):
|
||
|
|
"""pretty print for debug..."""
|
||
|
|
return "%s(%s, sh_type=%s, sh_flags=%s, "\
|
||
|
|
"sh_addr=0x%04x, sh_offset=0x%04x, sh_size=%s, sh_link=%s, "\
|
||
|
|
"sh_info=%s, sh_addralign=%s, sh_entsize=%s, lma=0x%04x)" % (
|
||
|
|
self.__class__.__name__,
|
||
|
|
self.name is not None and "%r" % self.name or "sh_name=%s" % self.sh_name,
|
||
|
|
self.sh_type, self.sh_flags, self.sh_addr,
|
||
|
|
self.sh_offset, self.sh_size, self.sh_link, self.sh_info,
|
||
|
|
self.sh_addralign, self.sh_entsize, self.lma)
|
||
|
|
|
||
|
|
class ELFProgramHeader:
|
||
|
|
"""Store and parse a program header"""
|
||
|
|
Elf32_Phdr = "<IIIIIIII" #header format
|
||
|
|
|
||
|
|
#segmet types
|
||
|
|
PT_NULL = 0
|
||
|
|
PT_LOAD = 1
|
||
|
|
PT_DYNAMIC = 2
|
||
|
|
PT_INTERP = 3
|
||
|
|
PT_NOTE = 4
|
||
|
|
PT_SHLIB = 5
|
||
|
|
PT_PHDR = 6
|
||
|
|
PT_LOPROC = 0x70000000L
|
||
|
|
PT_HIPROC = 0x7fffffffL
|
||
|
|
|
||
|
|
#segment flags
|
||
|
|
PF_R = 0x4 #segment is readable
|
||
|
|
PF_W = 0x2 #segment is writable
|
||
|
|
PF_X = 0x1 #segment is executable
|
||
|
|
|
||
|
|
def __init__(self):
|
||
|
|
"""create a new, empty segment/program header"""
|
||
|
|
(self.p_type, self.p_offset, self.p_vaddr, self.p_paddr,
|
||
|
|
self.p_filesz, self.p_memsz, self.p_flags, self.p_align) = [0]*8
|
||
|
|
self.data = None
|
||
|
|
|
||
|
|
def fromString(self, s):
|
||
|
|
"""parse header info from string"""
|
||
|
|
(self.p_type, self.p_offset, self.p_vaddr, self.p_paddr,
|
||
|
|
self.p_filesz, self.p_memsz, self.p_flags,
|
||
|
|
self.p_align) = struct.unpack(self.Elf32_Phdr, s)
|
||
|
|
|
||
|
|
def __str__(self):
|
||
|
|
"""pretty print for debug..."""
|
||
|
|
return "%s(p_type=%s, p_offset=0x%04x, p_vaddr=0x%04x, p_paddr=0x%04x, "\
|
||
|
|
"p_filesz=%s, p_memsz=%s, p_flags=%s, "\
|
||
|
|
"p_align=%s)" % (
|
||
|
|
self.__class__.__name__,
|
||
|
|
self.p_type, self.p_offset, self.p_vaddr, self.p_paddr,
|
||
|
|
self.p_filesz, self.p_memsz, self.p_flags,
|
||
|
|
self.p_align)
|
||
|
|
|
||
|
|
class ELFObject:
|
||
|
|
"""Object to read and handle an ELF object file"""
|
||
|
|
#header information
|
||
|
|
Elf32_Ehdr = "<16sHHIIIIIHHHHHH"
|
||
|
|
|
||
|
|
#offsets within e_ident
|
||
|
|
EI_MAG0 = 0 #File identification
|
||
|
|
EI_MAG1 = 1 #File identification
|
||
|
|
EI_MAG2 = 2 #File identification
|
||
|
|
EI_MAG3 = 3 #File identification
|
||
|
|
EI_CLASS = 4 #File class
|
||
|
|
EI_DATA = 5 #Data encoding
|
||
|
|
EI_VERSION = 6 #File version
|
||
|
|
EI_PAD = 7 #Start of padding bytes
|
||
|
|
EI_NIDENT = 16 #Size of e_ident[]
|
||
|
|
#elf file type flags
|
||
|
|
ET_NONE = 0 #No file type
|
||
|
|
ET_REL = 1 #Relocatable file
|
||
|
|
ET_EXEC = 2 #Executable file
|
||
|
|
ET_DYN = 3 #Shared object file
|
||
|
|
ET_CORE = 4 #Core file
|
||
|
|
ET_LOPROC = 0xff00 #Processor-specific
|
||
|
|
ET_HIPROC = 0xffff #Processor-specific
|
||
|
|
#ELF format
|
||
|
|
ELFCLASSNONE = 0 #Invalid class
|
||
|
|
ELFCLASS32 = 1 #32-bit objects
|
||
|
|
ELFCLASS64 = 2 #64-bit objects
|
||
|
|
#encoding
|
||
|
|
ELFDATANONE = 0 #Invalid data encoding
|
||
|
|
ELFDATA2LSB = 1 #See below
|
||
|
|
ELFDATA2MSB = 2 #See below
|
||
|
|
|
||
|
|
def __init__(self):
|
||
|
|
"""create a new elf object"""
|
||
|
|
(self.e_ident, self.e_type, self.e_machine, self.e_version,
|
||
|
|
self.e_entry, self.e_phoff, self.e_shoff,
|
||
|
|
self.e_flags, self.e_ehsize, self.e_phentsize, self.e_phnum,
|
||
|
|
self.e_shentsize, self.e_shnum, self.e_shstrndx) = [0]*14
|
||
|
|
|
||
|
|
def fromFile(self, fileobj):
|
||
|
|
"""read all relevant data from fileobj.
|
||
|
|
the file must be seekable"""
|
||
|
|
#get file header
|
||
|
|
(self.e_ident, self.e_type, self.e_machine, self.e_version,
|
||
|
|
self.e_entry, self.e_phoff, self.e_shoff,
|
||
|
|
self.e_flags, self.e_ehsize, self.e_phentsize, self.e_phnum,
|
||
|
|
self.e_shentsize, self.e_shnum, self.e_shstrndx) = struct.unpack(
|
||
|
|
self.Elf32_Ehdr, fileobj.read(struct.calcsize(self.Elf32_Ehdr)))
|
||
|
|
#verify if its a known format and realy an ELF file
|
||
|
|
if self.e_ident[0:4] != '\x7fELF' and\
|
||
|
|
self.e_ident[self.EI_CLASS] != self.ELFCLASS32 and\
|
||
|
|
self.e_ident[self.EI_DATA] != self.ELFDATA2LSB and\
|
||
|
|
self.e_ident[self.EI_VERSION] != 1:
|
||
|
|
raise ELFException("Not a valid ELF file")
|
||
|
|
|
||
|
|
#load programm headers
|
||
|
|
self.programmheaders = []
|
||
|
|
if self.e_phnum:
|
||
|
|
#load program headers
|
||
|
|
fileobj.seek(self.e_phoff)
|
||
|
|
for sectionnum in range(self.e_phnum):
|
||
|
|
shdr = (fileobj.read(self.e_phentsize) + '\0'* struct.calcsize(ELFProgramHeader.Elf32_Phdr))[0:struct.calcsize(ELFProgramHeader.Elf32_Phdr)]
|
||
|
|
psection = ELFProgramHeader()
|
||
|
|
psection.fromString(shdr)
|
||
|
|
if psection.p_offset: #skip if section has invalid offset in file
|
||
|
|
self.programmheaders.append(psection)
|
||
|
|
#~ #get the segment data from the file for each prg header
|
||
|
|
#~ for phdr in self.programmheaders:
|
||
|
|
#~ fileobj.seek(phdr.p_offset)
|
||
|
|
#~ phdr.data = fileobj.read(phdr.p_filesz)
|
||
|
|
#~ #pad if needed
|
||
|
|
#~ if phdr.p_filesz < phdr.p_memsz:
|
||
|
|
#~ phdr.data = phdr.data + '\0' * (phdr.p_memsz-phdr.p_filesz)
|
||
|
|
|
||
|
|
#load sections
|
||
|
|
self.sections = []
|
||
|
|
fileobj.seek(self.e_shoff)
|
||
|
|
for sectionnum in range(self.e_shnum):
|
||
|
|
shdr = (fileobj.read(self.e_shentsize) + '\0'* struct.calcsize(ELFSection.Elf32_Shdr))[0:struct.calcsize(ELFSection.Elf32_Shdr)]
|
||
|
|
elfsection = ELFSection()
|
||
|
|
elfsection.fromString(shdr)
|
||
|
|
self.sections.append(elfsection)
|
||
|
|
|
||
|
|
#load data for all sections
|
||
|
|
for section in self.sections:
|
||
|
|
fileobj.seek(section.sh_offset)
|
||
|
|
data = fileobj.read(section.sh_size)
|
||
|
|
section.data = data
|
||
|
|
if section.sh_type == ELFSection.SHT_STRTAB:
|
||
|
|
section.values = data.split('\0')
|
||
|
|
section.lma = self.getLMA(section)
|
||
|
|
|
||
|
|
#get section names
|
||
|
|
for section in self.sections:
|
||
|
|
start = self.sections[self.e_shstrndx].data[section.sh_name:]
|
||
|
|
section.name = start.split('\0')[0]
|
||
|
|
|
||
|
|
def getSection(self, name):
|
||
|
|
"""get section by name"""
|
||
|
|
for section in self.sections:
|
||
|
|
if section.name == name:
|
||
|
|
return section
|
||
|
|
|
||
|
|
def getProgrammableSections(self):
|
||
|
|
"""get all program headers that are marked as executable and
|
||
|
|
have suitable attributes to be code"""
|
||
|
|
res = []
|
||
|
|
for p in self.programmheaders:
|
||
|
|
#~ print p
|
||
|
|
#~ if section.sh_flags & self.SHF_ALLOC and section.name not in ('.data', '.data1', '.bss'):
|
||
|
|
#~ if p.p_type == ELFProgramHeader.PT_LOAD:# and p.p_paddr == p.p_vaddr and p.p_flags & ELFProgramHeader.PF_X:
|
||
|
|
if p.p_type == ELFProgramHeader.PT_LOAD:
|
||
|
|
res.append(p)
|
||
|
|
return res
|
||
|
|
|
||
|
|
def getLMA(self, section):
|
||
|
|
#magic load memory address calculation ;-)
|
||
|
|
for p in self.programmheaders:
|
||
|
|
if (p.p_paddr != 0 and \
|
||
|
|
p.p_type == ELFProgramHeader.PT_LOAD and \
|
||
|
|
p.p_vaddr != p.p_paddr and \
|
||
|
|
p.p_vaddr <= section.sh_addr and \
|
||
|
|
(p.p_vaddr + p.p_memsz >= section.sh_addr + section.sh_size) \
|
||
|
|
and (not (section.sh_flags & ELFSection.SHF_ALLOC and section.sh_type != ELFSection.SHT_NOBITS) \
|
||
|
|
or (p.p_offset <= section.sh_offset \
|
||
|
|
and (p.p_offset + p.p_filesz >= section.sh_offset + section.sh_size)))):
|
||
|
|
return section.sh_addr + p.p_paddr - p.p_vaddr
|
||
|
|
return section.sh_addr
|
||
|
|
|
||
|
|
def getSections(self):
|
||
|
|
"""get sections relevant for the application"""
|
||
|
|
res = []
|
||
|
|
for section in self.sections:
|
||
|
|
if section.sh_flags & ELFSection.SHF_ALLOC and section.sh_type != ELFSection.SHT_NOBITS:
|
||
|
|
res.append(section)
|
||
|
|
return res
|
||
|
|
|
||
|
|
def __str__(self):
|
||
|
|
"""pretty print for debug..."""
|
||
|
|
return "%s(self.e_type=%r, self.e_machine=%r, self.e_version=%r, sections=%r)" % (
|
||
|
|
self.__class__.__name__,
|
||
|
|
self.e_type, self.e_machine, self.e_version,
|
||
|
|
[section.name for section in self.sections])
|
||
|
|
|
||
|
|
|
||
|
|
if __name__ == '__main__':
|
||
|
|
print "This is only a module test!"
|
||
|
|
elf = ELFObject()
|
||
|
|
elf.fromFile(open("test.elf"))
|
||
|
|
if elf.e_type != ELFObject.ET_EXEC:
|
||
|
|
raise Exception("No executable")
|
||
|
|
print elf
|
||
|
|
|
||
|
|
#~ print repr(elf.getSection('.text').data)
|
||
|
|
#~ print [(s.name, hex(s.sh_addr)) for s in elf.getSections()]
|
||
|
|
print "-"*20
|
||
|
|
for p in elf.sections: print p
|
||
|
|
print "-"*20
|
||
|
|
for p in elf.getSections(): print p
|
||
|
|
print "-"*20
|
||
|
|
for p in elf.getProgrammableSections(): print p
|