dwarf-synthesis/README.md

dwarf-synthesis

A tool for automatic synthesis of DWARF.

The purpose of this tool is to take any given binary program or library, examine its assembly code and, based solely on that, generate the corresponding .eh_frame DWARF data.

Dependencies

This tool relies on

• opam set up with an OCaml 4.05 switch (see below),
• BAP version 1.5 as of today, which is available through OPAM;
• objcopy, often packaged as binutils
• libelf
• libdwarf
• libdwarfw, packaged as submodule

Installing dependencies

You should be able to easily install objcopy (binutils), libelf, libdwarf and opam via your package manager.

Once opam is set up, you will have to use an OCaml 4.05 opam switch. If you are not familiar with opam, we recommand using a fresh switch:

# If you never used opam before on this session:
opam init
eval $(opam config env)

opam switch create dwarf-synthesis ocaml-base-compiler.4.05.0  # With opam 2
# OR
opam switch dwarf-synthesis --alias-of 4.05.0                  # With opam 1.x

# Always:
eval $(opam config env)
opam install bap

Compiling

Simply run make to compile all the necessary tools, including compiling and installing the BAP plugin dwarfsynth.

Running with a wrapper script

To generate an .eh_frame section for some binary foo.bin and write the output as foo.eh.bin, you can run

./synthesize_dwarf foo.bin foo.eh.bin

You can also omit the second parameter to simply overwrite foo.bin.

Running by hand

If you want, for some reason, to run by hand the multiple components, you can follow this procedure (by using more appropriate file names, and, possibly, a temporary directory -- see mktemp -d).

Running the BAP plugin

bap prog_to_analyze.bin -p dwarfsynth --dwarfsynth-output tmp.marshal

Running ml_dwarf_write

You can get a help text with ./ml_dwarf_write.bin. Otherwise, you can run

./ml_dwarf_write.bin tmp.marshal prog_to_analyze.bin eh_frame_section`

Stitching the section into a binary

objcopy --add-section .eh_frame=eh_frame_section prog_to_analyze.bin prog_to_analyze.eh.bin

Commonly used commands

List a binary sections

objdump -h blah.bin

Strip a binary of its eh_frame

objcopy --remove-section '.eh_frame' --remove-section '.eh_frame_hdr' blah.bin