104 lines
4.4 KiB
Python
104 lines
4.4 KiB
Python
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"""Miscellaneous inspection tools
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"""
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from tempfile import NamedTemporaryFile, TemporaryDirectory
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import os
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import warnings
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from numba.core.errors import NumbaWarning
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def disassemble_elf_to_cfg(elf, mangled_symbol):
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"""
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Gets the CFG of the disassembly of an ELF object, elf, at mangled name,
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mangled_symbol, and renders it appropriately depending on the execution
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environment (terminal/notebook).
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"""
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try:
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import r2pipe
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except ImportError:
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raise RuntimeError("r2pipe package needed for disasm CFG")
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def get_rendering(cmd=None):
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from numba.pycc.platform import Toolchain # import local, circular ref
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if cmd is None:
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raise ValueError("No command given")
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with TemporaryDirectory() as tmpdir:
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# Write ELF as a temporary file in the temporary dir, do not delete!
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with NamedTemporaryFile(delete=False, dir=tmpdir) as f:
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f.write(elf)
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f.flush() # force write, radare2 needs a binary blob on disk
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# Now try and link the ELF, this helps radare2 _a lot_
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linked = False
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try:
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raw_dso_name = f'{os.path.basename(f.name)}.so'
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linked_dso = os.path.join(tmpdir, raw_dso_name)
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tc = Toolchain()
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tc.link_shared(linked_dso, (f.name,))
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obj_to_analyse = linked_dso
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linked = True
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except Exception as e:
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# link failed, mention it to user, radare2 will still be able to
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# analyse the object, but things like dwarf won't appear in the
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# asm as comments.
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msg = ('Linking the ELF object with the distutils toolchain '
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f'failed with: {e}. Disassembly will still work but '
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'might be less accurate and will not use DWARF '
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'information.')
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warnings.warn(NumbaWarning(msg))
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obj_to_analyse = f.name
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# catch if r2pipe can actually talk to radare2
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try:
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flags = ['-2', # close stderr to hide warnings
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'-e io.cache=true', # fix relocations in disassembly
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'-e scr.color=1', # 16 bit ANSI colour terminal
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'-e asm.dwarf=true', # DWARF decode
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'-e scr.utf8=true', # UTF8 output looks better
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]
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r = r2pipe.open(obj_to_analyse, flags=flags)
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r.cmd('aaaaaa') # analyse as much as possible
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# If the elf is linked then it's necessary to seek as the
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# DSO ctor/dtor is at the default position
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if linked:
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# r2 only matches up to 61 chars?! found this by experiment!
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mangled_symbol_61char = mangled_symbol[:61]
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# switch off demangle, the seek is on a mangled symbol
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r.cmd('e bin.demangle=false')
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# seek to the mangled symbol address
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r.cmd(f's `is~ {mangled_symbol_61char}[1]`')
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# switch demangling back on for output purposes
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r.cmd('e bin.demangle=true')
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data = r.cmd('%s' % cmd) # print graph
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r.quit()
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except Exception as e:
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if "radare2 in PATH" in str(e):
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msg = ("This feature requires 'radare2' to be "
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"installed and available on the system see: "
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"https://github.com/radareorg/radare2. "
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"Cannot find 'radare2' in $PATH.")
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raise RuntimeError(msg)
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else:
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raise e
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return data
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class DisasmCFG(object):
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def _repr_svg_(self):
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try:
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import graphviz
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except ImportError:
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raise RuntimeError("graphviz package needed for disasm CFG")
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jupyter_rendering = get_rendering(cmd='agfd')
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# this just makes it read slightly better in jupyter notebooks
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jupyter_rendering.replace('fontname="Courier",',
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'fontname="Courier",fontsize=6,')
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src = graphviz.Source(jupyter_rendering)
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return src.pipe('svg').decode('UTF-8')
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def __repr__(self):
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return get_rendering(cmd='agf')
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return DisasmCFG()
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