orbital/tools/patch-sections-1xx.py
2017-12-10 16:53:38 +01:00

317 lines
9.6 KiB
Python

#!/usr/bin/python
import argparse
import io
import lief
import os
import struct
# Indices
INDEX_NULL = 0
INDEX_INTERP = 1
INDEX_HASH = 2
INDEX_DYNSYM = 3
INDEX_DYNSTR = 4
INDEX_TEXT = 5
INDEX_DYNAMIC = 6
INDEX_SHSTRTAB = 7
# Utilities
class Section(object):
def __init__(self):
self.name_idx = 0
self.type = lief.ELF.SECTION_TYPES.NULL
self.flags = lief.ELF.SECTION_FLAGS.NONE
self.virtual_address = 0
self.offset = 0
self.size = 0
self.link = 0
self.information = 0
self.alignment = 0
self.entry_size = 0
# Helpers
self.name = ""
self.content = b""
def serialize(self):
section_fmt = 'IIQQQQIIQQ'
assert struct.calcsize(section_fmt) == 0x40
return struct.pack(section_fmt,
self.name_idx,
int(self.type),
int(self.flags),
self.virtual_address,
self.offset,
self.size,
self.link,
self.information,
self.alignment,
self.entry_size)
class Symbol(object):
def __init__(self, data):
symbol_fmt = 'IBBHQQ'
assert struct.calcsize(symbol_fmt) == 0x18
fields = struct.unpack(symbol_fmt, data)
self.name = fields[0]
self.info = fields[1]
self.other = fields[2]
self.shndx = fields[3]
self.value = fields[4]
self.size = fields[5]
def patch_i08(stream, offset, value):
data = struct.pack('B', value)
stream.seek(offset)
stream.write(data)
def patch_i16(stream, offset, value):
data = struct.pack('H', value)
stream.seek(offset)
stream.write(data)
def patch_i32(stream, offset, value):
data = struct.pack('I', value)
stream.seek(offset)
stream.write(data)
def patch_i64(stream, offset, value):
data = struct.pack('Q', value)
stream.seek(offset)
stream.write(data)
def read_i32(elf, addr):
data = bytes(elf.get_content_from_virtual_address(addr, 4))
value = struct.unpack('I', data)[0]
return value
def get_load_segment(elf, index=0):
for segment in elf.segments:
if segment.type != lief.ELF.SEGMENT_TYPES.LOAD:
continue
if index == 0:
return segment
index -= 1
raise Exception("Segment not found")
def get_dynamic_entry(elf, tag):
for de in elf.dynamic_entries:
if de.tag == tag:
return de
raise Exception("Segment not found")
# Sections
def create_section_null():
return Section()
def create_section_interp(elf):
section = Section()
section.name = ".interp"
section.type = lief.ELF.SECTION_TYPES.PROGBITS
section.flags = lief.ELF.SECTION_FLAGS.ALLOC
section.link = 0
section.information = 0
section.alignment = 1
section.entry_size = 0
section.size = len(elf.dynamic_entries) * section.entry_size
# Assume it appears after Ehdr+Phdr's of the first LOAD segment
hdr = elf.header
assert hdr.header_size == hdr.program_header_offset
segment = get_load_segment(elf, index=0)
section.virtual_address = segment.virtual_address
section.virtual_address += hdr.header_size
section.virtual_address += hdr.numberof_segments * hdr.program_header_size
section.offset = elf.virtual_address_to_offset(segment.virtual_address)
# Assume it appears before the .hash section
hash_vaddr = get_dynamic_entry(elf, lief.ELF.DYNAMIC_TAGS.HASH).value
assert hash_vaddr > section.virtual_address
section.size = hash_vaddr - section.virtual_address
return section
def create_section_hash(elf):
section = Section()
section.name = ".hash"
section.type = lief.ELF.SECTION_TYPES.HASH
section.flags = lief.ELF.SECTION_FLAGS.ALLOC
section.link = INDEX_DYNSYM
section.information = 0
section.alignment = 8
section.entry_size = 4
section.virtual_address = get_dynamic_entry(elf, lief.ELF.DYNAMIC_TAGS.HASH).value
section.offset = elf.virtual_address_to_offset(section.virtual_address)
hash_nbucket = read_i32(elf, section.virtual_address + 0x0)
hash_nchain = read_i32(elf, section.virtual_address + 0x4)
section.size = 8 + (hash_nbucket + hash_nchain) * 4
return section
def create_section_dynsym(elf):
section = Section()
section.name = ".dynsym"
section.type = lief.ELF.SECTION_TYPES.DYNSYM
section.flags = lief.ELF.SECTION_FLAGS.ALLOC
section.link = INDEX_DYNSTR
section.information = 0
section.alignment = 8
section.offset = 0
section.entry_size = 0
section.size = 0
for de in elf.dynamic_entries:
if de.tag == lief.ELF.DYNAMIC_TAGS.SYMTAB:
section.virtual_address = de.value
section.offset = elf.virtual_address_to_offset(de.value)
if de.tag == lief.ELF.DYNAMIC_TAGS.SYMENT:
section.entry_size = de.value
if not section.offset and not section.entry_size:
raise Exception("No dynamic entries for symbols")
assert section.entry_size == 0x18
while True:
symdata = bytes(elf.get_content_from_virtual_address(
section.virtual_address + section.size,
section.entry_size))
sym = Symbol(symdata)
if sym.size > 0xFFFFFFFF: break
section.size += section.entry_size
return section
def create_section_dynstr(elf):
section = Section()
section.name = ".dynstr"
section.type = lief.ELF.SECTION_TYPES.STRTAB
section.flags = lief.ELF.SECTION_FLAGS.ALLOC
section.link = 0
section.information = 0
section.alignment = 1
section.offset = 0
section.entry_size = 0
section.size = 0
for de in elf.dynamic_entries:
if de.tag == lief.ELF.DYNAMIC_TAGS.STRTAB:
section.virtual_address = de.value
section.offset = elf.virtual_address_to_offset(de.value)
if de.tag == lief.ELF.DYNAMIC_TAGS.STRSZ:
section.size = de.value
if not section.offset and not section.size:
raise Exception("No dynamic entries for strings")
return section
def create_section_text(elf):
section = Section()
section.name = ".text"
section.type = lief.ELF.SECTION_TYPES.PROGBITS
section.flags = lief.ELF.SECTION_FLAGS.ALLOC | lief.ELF.SECTION_FLAGS.EXECINSTR
section.link = 0
section.information = 0
section.alignment = 16
section.entry_size = 0
section.size = len(elf.dynamic_entries) * section.entry_size
# TODO
segment = get_load_segment(elf, index=0)
section.virtual_address = segment.virtual_address
section.offset = elf.virtual_address_to_offset(section.virtual_address)
section.size = segment.virtual_size
return section
def create_section_dynamic(elf):
section = Section()
section.name = ".dynamic"
section.type = lief.ELF.SECTION_TYPES.DYNAMIC
section.flags = lief.ELF.SECTION_FLAGS.WRITE | lief.ELF.SECTION_FLAGS.ALLOC
section.link = INDEX_DYNSTR
section.information = 0
section.alignment = 8
section.entry_size = 0x10
section.size = len(elf.dynamic_entries) * section.entry_size
# Assume .dynamic appears at the beginning of the second LOAD segment
segment = get_load_segment(elf, index=1)
section.virtual_address = segment.virtual_address
section.offset = elf.virtual_address_to_offset(segment.virtual_address)
return section
def create_section_shstrtab(sections):
section = Section()
section.name = ".shstrtab"
section.type = lief.ELF.SECTION_TYPES.STRTAB
section.flags = lief.ELF.SECTION_FLAGS.NONE
section.link = 0
section.information = 0
section.alignment = 1
section.offset = 0
section.entry_size = 0
section.size = 0
section.content = b''
for other_section in sections:
other_section.name_idx = len(section.content)
section.content += other_section.name.encode('ascii') + b'\x00'
section.name_idx = len(section.content)
section.content += section.name.encode('ascii') + b'\x00'
return section
def patch_sections(path_in, path_out):
elf = lief.parse(path_in)
assert len(elf.sections) == 0, "Expected an executable without sections"
sections = []
sections.append(create_section_null())
sections.append(create_section_interp(elf))
sections.append(create_section_hash(elf))
sections.append(create_section_dynsym(elf))
sections.append(create_section_dynstr(elf))
sections.append(create_section_text(elf))
sections.append(create_section_dynamic(elf))
sections.append(create_section_shstrtab(sections))
e_shentsize = 0x40
e_shoff = os.path.getsize(path_in)
e_shnum = len(sections)
e_shstrndx = INDEX_SHSTRTAB
with open(path_out, 'wb') as f:
with open(path_in, 'rb') as binary:
f.write(binary.read())
patch_i64(f, 0x28, e_shoff)
patch_i08(f, 0x3A, e_shentsize)
patch_i08(f, 0x3C, e_shnum)
patch_i08(f, 0x3E, e_shstrndx)
f.seek(0, io.SEEK_END)
offset = e_shoff + (e_shnum * e_shentsize)
for section in sections:
if section.content:
section.offset = offset
section.size = len(section.content)
offset += len(section.content)
f.write(section.serialize())
for section in sections:
f.write(section.content)
def main():
parser = argparse.ArgumentParser(
description='Generate ELF sections from dynamic entries in PS4 1.xx kernels.')
parser.add_argument('input',
metavar='input.elf', help='Path to input file',
)
parser.add_argument('output',
metavar='output.elf', help='Path to output file',
)
args = parser.parse_args()
patch_sections(args.input, args.output)
if __name__ == '__main__':
main()