mirror of
https://github.com/lief-project/LIEF
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lief-agent
81 lines
2.4 KiB
Python
81 lines
2.4 KiB
Python
#!/usr/bin/env python
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"""Inject a ``.symtab`` entry into a stripped ELF binary.
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Adds a fresh ``SYMTAB``/``STRTAB`` section pair and records a single
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``FUNC`` symbol (by default ``main`` at ``0x402A00``) so that
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debuggers such as ``gdb`` can resolve a symbolic breakpoint on a
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binary whose static symbol table was removed.
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Example:
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$ python elf_unstrip.py ./stripped ./unstripped
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$ gdb ./unstripped
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(gdb) break main
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Breakpoint 1 at 0x402a00
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"""
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import argparse
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import sys
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from lief import ELF
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def main() -> int:
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parser = argparse.ArgumentParser(description=__doc__.splitlines()[0])
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parser.add_argument("input", metavar="<elf>", help="Input (stripped) ELF binary")
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parser.add_argument("output", metavar="<out>", help="Output ELF binary")
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parser.add_argument("--address", type=lambda e: int(e, 0), default=0x402A00,
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help="Address of the added symbol (default: 0x402A00)")
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parser.add_argument("--name", default="main",
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help="Name of the added symbol (default: main)")
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args = parser.parse_args()
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binary = ELF.parse(args.input)
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if binary is None:
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print(f"Error: failed to parse '{args.input}' as ELF", file=sys.stderr)
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return 1
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symtab_section = ELF.Section()
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symtab_section.name = ""
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symtab_section.type = ELF.Section.TYPE.SYMTAB
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symtab_section.entry_size = 0x18
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symtab_section.alignment = 8
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symtab_section.link = len(binary.sections) + 1
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symtab_section.content = [0] * 100
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symstr_section = ELF.Section()
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symstr_section.name = ""
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symstr_section.type = ELF.Section.TYPE.STRTAB
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symstr_section.entry_size = 1
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symstr_section.alignment = 1
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symstr_section.content = [0] * 100
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binary.add(symtab_section, loaded=False)
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binary.add(symstr_section, loaded=False)
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null_symbol = ELF.Symbol()
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null_symbol.name = ""
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null_symbol.type = ELF.Symbol.TYPE.NOTYPE
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null_symbol.value = 0
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null_symbol.binding = ELF.Symbol.BINDING.LOCAL
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null_symbol.size = 0
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null_symbol.shndx = 0
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binary.add_symtab_symbol(null_symbol)
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symbol = ELF.Symbol()
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symbol.name = args.name
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symbol.type = ELF.Symbol.TYPE.FUNC
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symbol.value = args.address
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symbol.binding = ELF.Symbol.BINDING.LOCAL
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symbol.shndx = 14
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symbol = binary.add_symtab_symbol(symbol)
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print(symbol)
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binary.write(args.output)
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return 0
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if __name__ == "__main__":
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sys.exit(main())
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