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TuxSH/kernel80.py

Created April 19, 2019 11:32
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Kernel 8.0+ loader
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kernel80.py
# Copyright 2017 Reswitched Team
#
# Permission to use, copy, modify, and/or distribute this software for any purpose with or
# without fee is hereby granted, provided that the above copyright notice and this permission
# notice appear in all copies.
#
# THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS
# SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL
# THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY
# DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF
# CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE
# OR PERFORMANCE OF THIS SOFTWARE.
# nxo64.py: IDA loader (and library for reading nso/nro files)
import gzip, math, os, re, struct, sys
from struct import unpack as up, pack as pk
from io import BytesIO
from cStringIO import StringIO
(DT_NULL, DT_NEEDED, DT_PLTRELSZ, DT_PLTGOT, DT_HASH, DT_STRTAB, DT_SYMTAB, DT_RELA, DT_RELASZ,
DT_RELAENT, DT_STRSZ, DT_SYMENT, DT_INIT, DT_FINI, DT_SONAME, DT_RPATH, DT_SYMBOLIC, DT_REL,
DT_RELSZ, DT_RELENT, DT_PLTREL, DT_DEBUG, DT_TEXTREL, DT_JMPREL, DT_BIND_NOW, DT_INIT_ARRAY,
DT_FINI_ARRAY, DT_INIT_ARRAYSZ, DT_FINI_ARRAYSZ, DT_RUNPATH, DT_FLAGS) = xrange(31)
DT_GNU_HASH = 0x6ffffef5
DT_VERSYM = 0x6ffffff0
DT_RELACOUNT = 0x6ffffff9
DT_RELCOUNT = 0x6ffffffa
DT_FLAGS_1 = 0x6ffffffb
DT_VERDEF = 0x6ffffffc
DT_VERDEFNUM = 0x6ffffffd
STT_NOTYPE = 0
STT_OBJECT = 1
STT_FUNC = 2
STT_SECTION = 3
STB_LOCAL = 0
STB_GLOBAL = 1
STB_WEAK = 2
R_ARM_ABS32 = 2
R_ARM_TLS_DESC = 13
R_ARM_GLOB_DAT = 21
R_ARM_JUMP_SLOT = 22
R_ARM_RELATIVE = 23
R_AARCH64_ABS64 = 257
R_AARCH64_GLOB_DAT = 1025
R_AARCH64_JUMP_SLOT = 1026
R_AARCH64_RELATIVE = 1027
R_AARCH64_TLSDESC = 1031
MULTIPLE_DTS = set([DT_NEEDED])
class Range(object):
def __init__(self, start, size):
self.start = start
self.size = size
self.end = start+size
self._inclend = start+size-1
def overlaps(self, other):
return self.start <= other._inclend and other.start <= self._inclend
def includes(self, other):
return other.start >= self.start and other._inclend <= self._inclend
def __repr__(self):
return 'Range(0x%X -> 0x%X)' % (self.start, self.end)
class Segment(object):
def __init__(self, r, name, kind):
self.range = r
self.name = name
self.kind = kind
self.sections = []
def add_section(self, s):
for i in self.sections:
assert not i.range.overlaps(s.range), '%r overlaps %r' % (s, i)
self.sections.append(s)
class Section(object):
def __init__(self, r, name):
self.range = r
self.name = name
def __repr__(self):
return 'Section(%r, %r)' % (self.range, self.name)
def suffixed_name(name, suffix):
if suffix == 0:
return name
return '%s.%d' % (name, suffix)
class SegmentBuilder(object):
def __init__(self):
self.segments = []
def add_segment(self, start, size, name, kind):
r = Range(start, size)
for i in self.segments:
assert not r.overlaps(i.range), '%s: overlap: %08lx %08lx' % (name, start, size)
self.segments.append(Segment(r, name, kind))
def add_section(self, name, start, end=None, size=None):
assert end is None or size is None
if size is None:
size = end-start
assert size > 0
r = Range(start, size)
for i in self.segments:
if i.range.includes(r):
i.add_section(Section(r, name))
return
assert False, "no containing segment for %r" % (name,)
def flatten(self):
self.segments.sort(key=lambda s: s.range.start)
parts = []
for segment in self.segments:
suffix = 0
segment.sections.sort(key=lambda s: s.range.start)
pos = segment.range.start
for section in segment.sections:
if pos < section.range.start:
parts.append((pos, section.range.start, suffixed_name(segment.name, suffix), segment.kind))
suffix += 1
pos = section.range.start
parts.append((section.range.start, section.range.end, section.name, segment.kind))
pos = section.range.end
if pos < segment.range.end:
parts.append((pos, segment.range.end, suffixed_name(segment.name, suffix), segment.kind))
suffix += 1
pos = segment.range.end
return parts
class ElfSym(object):
def __init__(self, name, info, other, shndx, value, size):
self.name = name
self.shndx = shndx
self.value = value
self.size = size
self.vis = other & 3
self.type = info & 0xF
self.bind = info >> 4
def __repr__(self):
return 'Sym(name=%r, shndx=0x%X, value=0x%X, size=0x%X, vis=%r, type=%r, bind=%r)' % (
self.name, self.shndx, self.value, self.size, self.vis, self.type, self.bind)
class Kernel80(object):
def __init__(self, fileobj):
f = BinFile(fileobj)
crt0 = bytes(f.read(0x2000))
f.seek(0)
mapoff = crt0.find(b"\x3E\x40\x1C\xD5") - 0x30
textOffset, textEndOffset, rodataOffset, rodataEndOffset, \
dataOffset, dataEndOffset, bssOffset, bssEndOffset, ini1Offset, \
dynamicOffset, initArrayOffset, initArrayEndOffset = unpack("<12I", crt0[mapoff:mapoff+0x30])
b = 0x80060000
self.textoff = textOffset
self.textsize = textEndOffset - textOffset
self.rodataoff = rodataOffset
self.rodatasize = rodataEndOffset - rodataOffset
self.dataoff = dataOffset
self.datasize = dataEndOffset - dataOffset
flatsize = self.dataoff + self.datasize
self.binfile = f
self.dynamicoff = dynamicOffset
self.bssoff = bssOffset
self.bssend = bssEndOffset
self.bsssize = self.bssend - self.bssoff
self.segment_builder = builder = SegmentBuilder()
for off,sz,name,kind in [
(self.textoff, self.textsize, ".text", "CODE"),
(self.rodataoff, self.rodatasize, ".rodata", "CONST"),
(self.dataoff, self.datasize, ".data", "DATA"),
(self.bssoff, self.bsssize, ".bss", "BSS"),
]:
builder.add_segment(off, sz, name, kind)
# read dynamic
self.armv7 = False#(f.read_from('Q', self.dynamicoff) > 0xFFFFFFFF or f.read_from('Q', self.dynamicoff+0x10) > 0xFFFFFFFF)
self.offsize = 4 if self.armv7 else 8
f.seek(self.dynamicoff)
self.dynamic = dynamic = {}
for i in MULTIPLE_DTS:
dynamic[i] = []
for i in xrange((flatsize - self.dynamicoff) / 0x10):
tag, val = f.read('II' if self.armv7 else 'QQ')
if tag == DT_NULL:
break
if tag in MULTIPLE_DTS:
dynamic[tag].append(val)
else:
dynamic[tag] = val
dynamicend = f.tell()
builder.add_section('.dynamic', self.dynamicoff, dynamicend)
# read .dynstr
if DT_STRTAB in dynamic and DT_STRSZ in dynamic:
f.seek(dynamic[DT_STRTAB])
self.dynstr = f.read(dynamic[DT_STRSZ])
else:
self.dynstr = '\0'
print 'warning: no dynstr'
for startkey, szkey, name in [
(DT_STRTAB, DT_STRSZ, '.dynstr'),
(DT_INIT_ARRAY, DT_INIT_ARRAYSZ, '.init_array'),
(DT_FINI_ARRAY, DT_FINI_ARRAYSZ, '.fini_array'),
(DT_RELA, DT_RELASZ, '.rela.dyn'),
(DT_REL, DT_RELSZ, '.rel.dyn'),
(DT_JMPREL, DT_PLTRELSZ, ('.rel.plt' if self.armv7 else '.rela.plt')),
]:
if startkey in dynamic and szkey in dynamic:
builder.add_section(name, dynamic[startkey], size=dynamic[szkey])
self.needed = [self.get_dynstr(i) for i in self.dynamic[DT_NEEDED]]
# load .dynsym
self.symbols = symbols = []
f.seek(dynamic[DT_SYMTAB])
while True:
if dynamic[DT_SYMTAB] < dynamic[DT_STRTAB] and f.tell() >= dynamic[DT_STRTAB]:
break
if self.armv7:
st_name, st_value, st_size, st_info, st_other, st_shndx = f.read('IIIBBH')
else:
st_name, st_info, st_other, st_shndx, st_value, st_size = f.read('IBBHQQ')
if st_name > len(self.dynstr):
break
symbols.append(ElfSym(self.get_dynstr(st_name), st_info, st_other, st_shndx, st_value, st_size))
builder.add_section('.dynsym', dynamic[DT_SYMTAB], end=f.tell())
# .hash, .gnu.hash
if DT_HASH in dynamic and DT_GNU_HASH in dynamic and DT_SYMTAB in dynamic:
builder.add_section('.hash', dynamic[DT_HASH], end=dynamic[DT_GNU_HASH])
builder.add_section('.gnu.hash', dynamic[DT_GNU_HASH], end=dynamic[DT_SYMTAB])
self.plt_entries = []
self.relocations = []
locations = set()
if DT_REL in dynamic:
locations |= self.process_relocations(f, symbols, dynamic[DT_REL], dynamic[DT_RELSZ])
if DT_RELA in dynamic:
locations |= self.process_relocations(f, symbols, dynamic[DT_RELA], dynamic[DT_RELASZ])
if DT_JMPREL in dynamic:
# Note: 5.0 kernel doesn't have it
pltlocations = self.process_relocations(f, symbols, dynamic[DT_JMPREL], dynamic[DT_PLTRELSZ])
locations |= pltlocations
plt_got_start = min(pltlocations)
plt_got_end = max(pltlocations) + self.offsize
if DT_PLTGOT in dynamic:
builder.add_section('.got.plt', dynamic[DT_PLTGOT], end=plt_got_end)
if not self.armv7:
f.seek(0)
text = f.read(self.textsize)
last = 12
while True:
pos = text.find(struct.pack('<I', 0xD61F0220), last)
if pos == -1: break
last = pos+1
if (pos % 4) != 0: continue
off = pos - 12
a, b, c, d = struct.unpack_from('<IIII', text, off)
if d == 0xD61F0220 and (a & 0x9f00001f) == 0x90000010 and (b & 0xffe003ff) == 0xf9400211:
base = off & ~0xFFF
immhi = (a >> 5) & 0x7ffff
immlo = (a >> 29) & 3
paddr = base + ((immlo << 12) | (immhi << 14))
poff = ((b >> 10) & 0xfff) << 3
target = paddr + poff
if plt_got_start <= target < plt_got_end:
self.plt_entries.append((off, target))
builder.add_section('.plt', min(self.plt_entries)[0], end=max(self.plt_entries)[0] + 0x10)
# try to find the ".got" which should follow the ".got.plt"
good = False
got_end = plt_got_end + self.offsize
while got_end in locations and (DT_INIT_ARRAY not in dynamic or got_end < dynamic[DT_INIT_ARRAY]):
good = True
got_end += self.offsize
if good:
builder.add_section('.got', plt_got_end, end=got_end)
else:
# .got is between .dynamic and .init_array on 5.0
builder.add_section('.got', dynamicend, dynamic[DT_INIT_ARRAY])
self.sections = []
for start, end, name, kind in builder.flatten():
self.sections.append((start, end, name, kind))
def process_relocations(self, f, symbols, offset, size):
locations = set()
f.seek(offset)
relocsize = 8 if self.armv7 else 0x18
for i in xrange(size / relocsize):
# NOTE: currently assumes all armv7 relocs have no addends,
# and all 64-bit ones do.
if self.armv7:
offset, info = f.read('II')
addend = None
r_type = info & 0xff
r_sym = info >> 8
else:
offset, info, addend = f.read('QQq')
r_type = info & 0xffffffff
r_sym = info >> 32
sym = symbols[r_sym] if r_sym != 0 else None
if r_type != R_AARCH64_TLSDESC and r_type != R_ARM_TLS_DESC:
locations.add(offset)
self.relocations.append((offset, r_type, sym, addend))
return locations
def get_dynstr(self, o):
return self.dynstr[o:self.dynstr.index('\0', o)]
class NxoException(Exception):
pass
def load_nxo(fileobj):
fileobj.seek(0)
return Kernel80(fileobj)
try:
import idaapi
import idc
except ImportError:
pass
else:
# IDA specific code
def accept_file(li, n):
if not isinstance(n, (int,long)) or n == 0:
li.seek(0)
if li.read(4) == '\xDFO\x03\xD5':
return '8.0+ KNX'
return 0
def ida_make_offset(f, ea):
if f.armv7:
idc.MakeDword(ea)
else:
idc.MakeQword(ea)
idc.OpOff(ea, 0, 0)
def find_bl_targets(text_start, text_end):
targets = set()
for pc in range(text_start, text_end, 4):
d = Dword(pc)
if (d & 0xfc000000) == 0x94000000:
imm = d & 0x3ffffff
if imm & 0x2000000:
imm |= ~0x1ffffff
if 0 <= imm <= 2:
continue
target = pc + imm * 4
if target >= text_start and target < text_end:
targets.add(target)
return targets
def load_file(li, neflags, format):
idaapi.set_processor_type("arm", SETPROC_ALL|SETPROC_FATAL)
f = load_nxo(li)
if f.armv7:
idc.SetShortPrm(idc.INF_LFLAGS, idc.GetShortPrm(idc.INF_LFLAGS) | idc.LFLG_PC_FLAT)
else:
idc.SetShortPrm(idc.INF_LFLAGS, idc.GetShortPrm(idc.INF_LFLAGS) | idc.LFLG_64BIT)
idc.SetCharPrm(idc.INF_DEMNAMES, idaapi.DEMNAM_GCC3)
idaapi.set_compiler_id(idaapi.COMP_GNU)
idaapi.add_til2('gnulnx_arm' if f.armv7 else 'gnulnx_arm64', 1)
#loadbase = 0x60000000 if f.armv7 else 0x7100000000
loadbase = 0x80060000
#loadbase = 0xFFFFFF8000060000
f.binfile.seek(0)
as_string = f.binfile.read(f.bssoff)
idaapi.mem2base(as_string, loadbase)
for start, end, name, kind in f.sections:
if name.startswith('.got'):
kind = 'CONST'
idaapi.add_segm(0, loadbase+start, loadbase+end, name, kind)
segm = idaapi.get_segm_by_name(name)
if kind == 'CONST':
segm.perm = idaapi.SEGPERM_READ
elif kind == 'CODE':
segm.perm = idaapi.SEGPERM_READ | idaapi.SEGPERM_EXEC
elif kind == 'DATA':
segm.perm = idaapi.SEGPERM_READ | idaapi.SEGPERM_WRITE
elif kind == 'BSS':
segm.perm = idaapi.SEGPERM_READ | idaapi.SEGPERM_WRITE
idaapi.update_segm(segm)
idaapi.set_segm_addressing(segm, 1 if f.armv7 else 2)
# do imports
# TODO: can we make imports show up in "Imports" window?
undef_count = 0
for s in f.symbols:
if not s.shndx and s.name:
undef_count += 1
last_ea = max(loadbase + end for start, end, name, kind in f.sections)
undef_entry_size = 8
undef_ea = ((last_ea + 0xFFF) & ~0xFFF) + undef_entry_size # plus 8 so we don't end up on the "end" symbol
idaapi.add_segm(0, undef_ea, undef_ea+undef_count*undef_entry_size, "UNDEF", "XTRN")
segm = idaapi.get_segm_by_name("UNDEF")
segm.type = idaapi.SEG_XTRN
idaapi.update_segm(segm)
for i,s in enumerate(f.symbols):
if not s.shndx and s.name:
idc.MakeQword(undef_ea)
idaapi.do_name_anyway(undef_ea, s.name)
s.resolved = undef_ea
undef_ea += undef_entry_size
elif i != 0:
assert s.shndx
s.resolved = loadbase + s.value
if s.name:
if s.type == STT_FUNC:
print hex(s.resolved), s.name
idaapi.add_entry(s.resolved, s.resolved, s.name, 0)
else:
idaapi.do_name_anyway(s.resolved, s.name)
else:
# NULL symbol
s.resolved = 0
funcs = set()
for s in f.symbols:
if s.name and s.shndx and s.value:
if s.type == STT_FUNC:
funcs.add(loadbase+s.value)
got_name_lookup = {}
for offset, r_type, sym, addend in f.relocations:
target = offset + loadbase
if r_type in (R_ARM_GLOB_DAT, R_ARM_JUMP_SLOT, R_ARM_ABS32):
if not sym:
print 'error: relocation at %X failed' % target
else:
idaapi.put_long(target, sym.resolved)
elif r_type == R_ARM_RELATIVE:
idaapi.put_long(target, idaapi.get_long(target) + loadbase)
elif r_type in (R_AARCH64_GLOB_DAT, R_AARCH64_JUMP_SLOT, R_AARCH64_ABS64):
idaapi.put_qword(target, sym.resolved + addend)
if addend == 0:
got_name_lookup[offset] = sym.name
elif r_type == R_AARCH64_RELATIVE:
idaapi.put_qword(target, loadbase + addend)
if addend < f.textsize:
funcs.add(loadbase + addend)
else:
print 'TODO r_type %d' % (r_type,)
ida_make_offset(f, target)
for func, target in f.plt_entries:
if target in got_name_lookup:
addr = loadbase + func
funcs.add(addr)
idaapi.do_name_anyway(addr, got_name_lookup[target])
funcs |= find_bl_targets(loadbase, loadbase+f.textsize)
for addr in sorted(funcs, reverse=True):
idc.AutoMark(addr, AU_CODE)
idc.AutoMark(addr, AU_PROC)
return 1
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