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codezero/tools/pyelf/elf.py
Bahadir Balban e2b791a3d8 Initial commit
2008-01-13 13:53:52 +00:00

501 lines
15 KiB
Python
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from aistruct import GFile, BitPoker, AIStruct
import StringIO
import sys
class Elf32Header(AIStruct):
EI_MAGIC = [0x7f, ord('E'), ord('L'), ord('F')]
EI_CLASS_32 = 1
EI_CLASS_64 = 2
EI_DATA_LSB = 1
EI_DATA_MSB = 2
EI_TYPE_NONE = 0
EI_TYPE_REL = 1
EI_TYPE_EXEC = 2
EI_TYPE_DYN = 3
EI_TYPE_CORE = 4
EI_TYPE_NUM = 5
EI_TYPE_LOPROC = 0xff00
EI_TYPE_HIPROC = 0xffff
MACHINE_NONE = 0
MACHINE_SPARC = 2
MACHINE_386 = 3
MACHINE_MIPS = 8
MACHINE_MIPS_RS4_BE = 10
MACHINE_SPARC32PLUS = 18
MACHINE_ARM = 40
MACHINE_FAKE_ALPHA = 41
MACHINE_SPARCV9 = 43
MACHINE_IA_64 = 50
MACHINE_ALPHA = 0x9026
VERSION_NONE = 0
VERSION_CURRENT = 1
def __init__(self):
AIStruct.__init__(self, AIStruct.SIZE32)
self.setup(
('UINT8', 'ei_magic', {'times': 4}),
('UINT8', 'ei_class', {'names' : { 1: "ELF32", 2: "ELF64" }} ),
('UINT8', 'ei_data', {'names' : { 1 : "2's complement, little endian", 2: "2's complement, big endian" }}),
('UINT8', 'ei_version', {'names' : { 1 : "1 (current)" }}),
('UINT8', 'ei_osabi', { 'names' : { 0 : "UNIX - System V", 1 : "HP-UX Operating System", 255 : "Standalone application"}}),
('UINT8', 'ei_abiversion'),
('UINT8', 'ei_padding', {'times': 7}),
('UINT16', 'e_type', { 'names' : { 2 : "EXEC (Executable file)" }} ),
('UINT16', 'e_machine', { 'names' : { 3 : "Intel 80836" } }),
('UINT32', 'e_version', {'format': "0x%x" }),
('UINT32', 'e_entry', {'format': "0x%x" }),
('UINT32', 'e_phoff', { 'format' : "%d (bytes into file)" }),
('UINT32', 'e_shoff', { 'format' : "%d (bytes into file)" }),
('UINT32', 'e_flags', {'format': "0x%x" }),
('UINT16', 'e_ehsize', { 'format' : "%d (bytes)" } ),
('UINT16', 'e_phentsize', { 'format' : "%d (bytes)" } ),
('UINT16', 'e_phnum'),
('UINT16', 'e_shentsize', { 'format' : "%d (bytes)" } ),
('UINT16', 'e_shnum'),
('UINT16', 'e_shstrndx')
)
def __str__(self):
f = StringIO.StringIO()
f.write("ELF Header:\n")
for name, attr in [("Class", "ei_class"),
("Data", "ei_data"),
("Version", "ei_version"),
("OS/ABI", "ei_osabi"),
("ABI Version", "ei_abiversion"),
("Type", "e_type"),
("Machine", "e_machine"),
("Version", "e_version"),
("Entry point address", "e_entry"),
("Start of program headers", "e_phoff"),
("Start of section headers", "e_shoff"),
("Flags", "e_flags"),
("Size of this header", "e_ehsize"),
("Size of program headers", "e_phentsize"),
("Number of program headers", "e_phnum"),
("Size of section headers", "e_shentsize"),
("Number of section headers", "e_shnum"),
("Section header string table index", "e_shstrndx"),
]:
f.write(" %-35s%s\n" % ("%s:" % name, getattr(self.ai, attr)))
return f.getvalue()
class Elf64Header(Elf32Header):
# Inherit from Elf32Header to get the constants.
def __init__(self):
AIStruct.__init__(self, AIStruct.SIZE64)
self.setup(
('UINT8', 'ei_magic', {'times': 4}),
('UINT8', 'ei_class'),
('UINT8', 'ei_data'),
('UINT8', 'ei_version'),
('UINT8', 'ei_padding', {'times': 9}),
('UINT16', 'e_type'),
('UINT16', 'e_machine'),
('UINT32', 'e_version'),
('UINT64', 'e_entry'),
('UINT64', 'e_phoff'),
('UINT64', 'e_shoff'),
('UINT32', 'e_flags'),
('UINT16', 'e_ehsize'),
('UINT16', 'e_phentsize'),
('UINT16', 'e_phnum'),
('UINT16', 'e_shentsize'),
('UINT16', 'e_shnum'),
('UINT16', 'e_shstrndx')
)
class Elf32SectionHeader(AIStruct):
SHF_WRITE = 1 << 0
SHF_ALLOC = 1 << 1
SHF_EXECINSTR = 1 << 2
def __init__(self, *args, **kwargs):
AIStruct.__init__(self, AIStruct.SIZE32)
self.elffile = kwargs["elffile"]
self.index = kwargs["index"]
def format_flags(x):
if x == (self.SHF_WRITE | self.SHF_ALLOC):
return "WA"
if x == (self.SHF_EXECINSTR | self.SHF_ALLOC):
return "AX"
if x == self.SHF_WRITE:
return "W"
if x == self.SHF_ALLOC:
return "A"
if x == self.SHF_EXECINSTR:
return "X"
return "%x" % x
self.mutated = 0
self._name = None
self.setup(
('UINT32', 'sh_name', {"format" : self.elffile.get_name}),
('UINT32', 'sh_type', {"names" : {0:"NULL", 1:"PROGBITS", 2:"SYMTAB", 3:"STRTAB", 8:"NOBITS"}}),
('UINT32', 'sh_flags', {"format": format_flags}),
('UINT32', 'sh_addr', {"format" : "%08x"}),
('UINT32', 'sh_offset', {"format" : "%06x"}),
('UINT32', 'sh_size', {"format" : "%06x"}),
('UINT32', 'sh_link'),
('UINT32', 'sh_info', {"format" : "%3d"}),
('UINT32', 'sh_addralign', {"format" : "%2d"}),
('UINT32', 'sh_entsize', {"format" : "%02x"}),
)
def get_name(self):
if not self._name:
self._name = self.elffile.get_name(self.ai.sh_name)
return self._name
def set_name(self, value):
self._name = value
name = property(get_name, set_name)
def get_sym_name(self, value):
strtab = ElfFileStringTable \
(self.elffile.gfile, self.elffile.sheaders[self.ai.sh_link.get()])
return strtab.read(value)
def allocable(self):
return self.ai.sh_flags.get() & self.SHF_ALLOC
def writable(self):
return self.ai.sh_flags.get() & self.SHF_WRITE
def executable(self):
return self.ai.sh_flags.get() & self.SHF_EXECINSTR
def get_perms(self):
# Only call on allocatable
assert self.allocable()
rwx = (1 << 2);
if self.writable():
rwx |= (1 << 1)
if self.executable():
rwx |= 1
return rwx
def container(self, cls):
size = cls(section = self).struct_size()
return ElfFileContainer(self.elffile.gfile, AIStruct.SIZE32, self.ai.sh_offset.get(),
size, self.ai.sh_size.get() / size,
cls, section=self)
class Elf64SectionHeader(AIStruct):
def __init__(self, *args, **kwargs):
AIStruct.__init__(self, AIStruct.SIZE64)
self.setup(
('UINT32', 'sh_name'),
('UINT32', 'sh_type'),
('UINT64', 'sh_flags'),
('UINT64', 'sh_addr'),
('UINT64', 'sh_offset'),
('UINT64', 'sh_size'),
('UINT32', 'sh_link'),
('UINT32', 'sh_info'),
('UINT64', 'sh_addralign'),
('UINT64', 'sh_entsize'),
)
class Elf32ProgramHeader(AIStruct):
PT_NULL = 0
PT_NULL = 0
PT_LOAD = 1
PT_DYNAMIC = 2
PT_INTERP = 3
PT_NOTE = 4
PT_SHLIB = 5
PT_PHDR = 6
PT_NUM = 7
PT_LOOS = 0x60000000
PT_HIOS = 0x6fffffff
PT_LOPROC = 0x70000000
PT_HIPROC = 0x7fffffff
PF_X = 1 << 0
PF_W = 1 << 1
PF_R = 1 << 2
PF_MASKPROC = 0xf0000000L
def __init__(self, *args, **kwargs):
AIStruct.__init__(self, AIStruct.SIZE32)
self.elffile = kwargs["elffile"]
def format_flags(x):
the_str = [' ', ' ', ' ']
if (x & self.PF_X):
the_str[2] = 'E'
if (x & self.PF_W):
the_str[1] = 'W'
if (x & self.PF_R):
the_str[0] = 'R'
return "".join(the_str)
self.setup(
('UINT32', 'p_type', {"names" :
{0: "NULL",
1: "LOAD",
2 : "DYNAMIC",
3 : "INTERP",
4 : "NOTE",
1685382481 : "GNU_STACK",
1694766464 : "PAX_FLAGS",
}
} ),
('UINT32', 'p_offset', {"format": "0x%06x"}),
('UINT32', 'p_vaddr', {"format": "0x%08x"}),
('UINT32', 'p_paddr', {"format": "0x%08x"}),
('UINT32', 'p_filesz', {"format": "0x%05x"}),
('UINT32', 'p_memsz', {"format": "0x%05x"}),
('UINT32', 'p_flags', {"format": format_flags}),
('UINT32', 'p_align', {"format": "0x%x"}),
)
class Elf64ProgramHeader(Elf32ProgramHeader):
def __init__(self, *args, **kwargs):
AIStruct.__init__(self, AIStruct.SIZE64)
self.setup(
('UINT32', 'p_type', {"names" : {0: "NULL", 1: "LOAD", 2 : "DYNAMIC", 3 : "INTERP", 4 : "NOTE"}} ),
('UINT32', 'p_flags'),
('UINT64', 'p_offset'),
('UINT64', 'p_vaddr'),
('UINT64', 'p_paddr'),
('UINT64', 'p_filesz'),
('UINT64', 'p_memsz'),
('UINT64', 'p_align'),
)
class ElfFileException(Exception):
pass
class ElfFileNotElfException(ElfFileException):
pass
class ElfFileContainer(object):
def __init__(self, gfile, word_size, offset, entsize, number, cls, **kwargs):
self.gfile = gfile
self.word_size = word_size
self.offset = offset
self.entsize = entsize
self.number = number
self.cls = cls
self.mutated = 0
self.container = []
self.kwargs = kwargs
def mutate(self):
print "Making it mutable"
for each in self:
self.container.append(each)
self.mutated = 1
def __delitem__(self, idx):
if not self.mutated: self.mutate()
self.container.__delitem__(idx)
def __getitem__(self, idx):
if type(idx) == type(""):
# Act like a dictionary
for each in self:
if str(each.ai.sh_name) == idx:
return each
raise "badness"
else:
if self.mutated:
print "mutated", idx, self.container
return self.container[idx]
else:
num = idx
assert num >= 0
if num >= self.number:
raise StopIteration()
inst = self.cls(self.word_size, index=num, **self.kwargs)
poker = BitPoker.new_with_gfile(self.gfile, self.offset + (self.entsize * num))
inst.read_from_poker(poker)
return inst
def __len__(self):
return self.number
class ElfFileProgramHeaderContainer(ElfFileContainer):
def __str__(self):
f = StringIO.StringIO()
f.write("Program Headers:\n")
format_str = " %-15s%-9s%-11s%-11s%-8s%-8s%-4s%s\n"
f.write(format_str % ("Type", "Offset", "VirtAddr",
"PhysAddr", "FileSiz", "MemSiz", "Flg", "Align"))
for header in self:
x = header.ai
f.write(format_str % (x.p_type, x.p_offset, x.p_vaddr,
x.p_paddr, x.p_filesz, x.p_memsz, x.p_flags, x.p_align))
return f.getvalue()
class ElfFileSectionHeaderContainer(ElfFileContainer):
def __str__(self):
f = StringIO.StringIO()
f.write("There are %d section headers, starting at offset 0x%x:\n\n" % (len(self), self.kwargs["elffile"].header.ai.e_shoff.get()))
f.write("Section Headers:\n")
format_str = " [%2s] %-17.17s %-15s %-8s %-6s %-6s %2s %3s %2s %-3s %-2s\n"
f.write(format_str % ("Nr", "Name", "Type", "Addr", "Off", "Size",
"ES", "Flg", "Lk", "Inf", "Al"))
for idx, header in enumerate(self):
x = header.ai
f.write(format_str % (idx, x.sh_name, x.sh_type, x.sh_addr,
x.sh_offset, x.sh_size, x.sh_entsize,
x.sh_flags, x.sh_link, x.sh_info,
x.sh_addralign))
return f.getvalue()
class ElfFileStringTable(object):
def __init__(self, gfile, section_header):
file_offset = section_header.ai.sh_offset
self.poker = BitPoker.new_with_gfile(gfile, file_offset)
def read(self, offset):
return self.poker.read_c_string(offset)
class Symbols(AIStruct):
def __init__(self, *args, **kwargs):
AIStruct.__init__(self, AIStruct.SIZE32)
self.section = kwargs["section"]
self.setup(
('UINT32', 'st_name', {"format" : self.section.get_sym_name}),
('UINT32', 'value'),
('UINT32', 'size'),
('UINT8', 'info'),
('UINT8', 'other'),
('UINT16', 'st_shndx')
)
def __str__(self):
return "[%s] 0x%08x %5d %3d" % \
(self.ai.st_name, self.ai.value.get(),
self.ai.size.get(), self.ai.st_shndx.get())
class ElfFileSymbolTable(object):
def __init__(self, gfile, section_header):
self.header = section_header
file_offset = section_header.ai.sh_offset
self.poker = BitPoker.new_with_gfile(gfile, file_offset)
def get_symbols(self, section_num = None):
if section_num:
return [ sym for sym in self.header.container(Symbols) if sym.ai.st_shndx.get() == section_num]
else:
return self.header.container(Symbols)
class ElfFile(object):
WORD_SIZE_MAP = {Elf32Header.EI_CLASS_32: Elf32Header.SIZE32,
Elf32Header.EI_CLASS_64: Elf32Header.SIZE64}
BYTE_ORDER_MAP = {Elf32Header.EI_DATA_LSB: 'lsb',
Elf32Header.EI_DATA_MSB: 'msb'}
HEADER_MAP = {Elf32Header.SIZE32: Elf32Header, Elf64Header.SIZE64: Elf64Header}
PROGRAM_HEADER_MAP = {Elf32Header.SIZE32: Elf32ProgramHeader, Elf64Header.SIZE64: Elf64ProgramHeader}
SECTION_HEADER_MAP = {Elf32Header.SIZE32: Elf32SectionHeader, Elf64Header.SIZE64: Elf64SectionHeader}
""" Python representation of an Elf file. """
def __init__(self, gfile, byte_ordering, word_size):
self.gfile = gfile
self.gfile.set_byte_ordering(byte_ordering)
self.byte_order = byte_ordering
self.word_size = word_size
self.header = ElfFile.HEADER_MAP[self.word_size]()
self.header.read_from_poker(BitPoker.new_with_gfile(self.gfile, 0))
# Setup the parts of the file
# ... program headers
self.pheaders = ElfFileProgramHeaderContainer \
(gfile, word_size, self.header.ai.e_phoff, self.header.ai.e_phentsize,
self.header.ai.e_phnum.get(), ElfFile.PROGRAM_HEADER_MAP[word_size], elffile=self)
# ... section headers
self.sheaders = ElfFileSectionHeaderContainer \
(gfile, word_size, self.header.ai.e_shoff, self.header.ai.e_shentsize,
self.header.ai.e_shnum.get(), ElfFile.SECTION_HEADER_MAP[word_size], elffile=self)
# ... string table
if self.header.ai.e_shstrndx != 0:
self.string_table = ElfFileStringTable \
(self.gfile, self.sheaders[self.header.ai.e_shstrndx])
# ... symbol table
self.symtable = None
for header in self.sheaders:
if header.get_name() == ".symtab":
self.symtable = ElfFileSymbolTable(self.gfile, header)
def set_source(self, poker):
self.source_poker = poker
def get_name(self, idx):
return self.string_table.read(idx)
def print_info(self):
print "* Information for ELF file:"
print "* Header info:"
self.header.print_info()
def write_file(selfm, filename):
# Write out head
print "Wirintg out", filename
def from_file(filename):
gfile = GFile.existing(filename)
poker = BitPoker()
poker.set_mmapfile(gfile.mapping, 0) # Offset of 0 from start of file.
poker.set_byte_ordering('lsb') # Use default because we don't (yet) know
header = Elf32Header() # Once again, use a default size.
header.read_from_poker(poker)
# Examine the header for info we need.
# Check the magic first. If we don't and the file is non-ELF, chances are
# class & data won't match which will result in a confusing error message
if header.ai.ei_magic != Elf32Header.EI_MAGIC:
raise ElfFileNotElfException("Wanted magic %r, got %r" \
% (Elf32Header.EI_MAGIC, header.ai.ei_magic))
word_size = ElfFile.WORD_SIZE_MAP[header.ai.ei_class.get()]
byte_order = ElfFile.BYTE_ORDER_MAP[header.ai.ei_data.get()]
return ElfFile(gfile, byte_order, word_size)
from_file = staticmethod(from_file)
def test():
"Test suite"
elf_file = ElfFile.from_file("a.out")
# Check can load an elf
success = 1
try:
x = ElfFile.from_file("a.out")
except:
success = 0
assert success
# CHeck can't load not and elf
success = 0
try:
x = ElfFile.from_file("pyelf.py")
except:
success = 1
assert success
def main():
filename = sys.argv[1] # Consider this a usage message :)
elf_file = ElfFile.from_file(filename)
elf_file.print_info()
if __name__ == '__main__':
if sys.argv[1] != "test":
main()
else:
test()
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