A fast disassembler which is accurate enough for the resulting assembly code to be reassembled. The disassembler implemented using the datalog (souffle) declarative logic programming language to compile disassembly rules and heuristics. The disassembler first parses ELF file information and decodes a superset of possible instructions to create an initial set of datalog facts. These facts are analyzed to identify code location, symbolization, and function boundaries. The results of this analysis, a refined set of datalog facts, are then translated to the GTIRB intermediate representation for binary analysis and reverse engineering. The GTIRB pretty printer may then be used to pretty print the GTIRB to reassemblable assembly code.
ddisasm uses C++17, and requires a compiler which supports that standard such as gcc 7, clang 6, or MSVC 2017.
To build and install ddisasm, the following requirements should be installed:
- gtirb
- gtirb-pprinter
- Capstone, version 4.0.1 or later
- Souffle, version 1.7.0 or higher
- Must be configured with support for 64 bit numbers (via
--enable-64bit-domainduring configuration)
- Must be configured with support for 64 bit numbers (via
- libehp, version 1.0.0 or higher
- LIEF, version 0.9.0 or higher
- libdwarf
Note that these versions are newer than what your package manager may provide by default: This is true on Ubuntu 18, Debian 10, and others. Prefer building these dependencies from sources to avoid versioning problems.
Use the following options to configure cmake:
-
You can tell CMake which compiler to use with
-DCMAKE_CXX_COMPILER=<compiler>. -
Normally CMake will find GTIRB automatically, but if it does not you can pass
-Dgtirb_DIR=<path-to-gtirb-build>. -
ddisasm can make use of GTIRB in static library form (instead of shared library form, the default) if you use the flag
-DDDISASM_BUILD_SHARED_LIBS=OFF.
Once the dependencies are installed, you can configure and build as follows:
$ cmake ./ -Bbuild
$ cd build
$ make
The directory .ci contains several Docker files to build ddisasm under different OS and compiler. These docker files assume that GTIRB, gtirb-pprinter and libehp have been checked out inside the ddisasm directory.
The steps to build ddisasm inside a ubuntu 16 image using clang are:
git clone https://github.com/GrammaTech/ddisasm.git
cd ddisasm
git clone https://github.com/GrammaTech/gtirb.git
git clone https://github.com/GrammaTech/gtirb-pprinter.git
git clone https://git.zephyr-software.com/opensrc/libehp
docker build -f .ci/Dockerfile.ubuntu16-clang -t ddisasm-ubuntu16-clang .
Once ddisasm is built, we can run complete analysis on a file by
calling build/bin/ddisasm'. For example, we can run the analysis on one
of the examples as follows:
cd build/bin && ./ddisasm ../../examples/ex1/ex --asm ex.s
Ddisasm accepts the following parameters:
--help
: produce help message
--ir arg
: GTIRB output file
--json arg
: GTIRB json output file
--asm arg
: ASM output file
--debug
: if the assembly code is printed, it is printed with debugging information
--debug-dir arg
: location to write CSV files for debugging
-K [ --keep-functions ] arg
: Print the given functions even if they are skipped by default (e.g. _start)
--self-diagnose
: This option is useful for debugging. Use relocation information to emit a self diagnosis
of the symbolization process. This option only works if the target
binary contains complete relocation information. You can enable
that in ld using the option --emit-relocs.
-F [ --skip-function-analysis ]
: Skip additional analyses to compute more precise function boundaries.
-j [ --threads ]
: Number of cores to use. It is set to the number of cores in the machine by default.
The directory tests/ contains the script reassemble_and_test.sh to
rewrite and test a complete project. reassemble_and_test.sh rebuilds
a project using the compiler and compiler flags specified in the
enviroment variables CC and CFLAGS (make -e), rewrites the binary
and run the project tests on the new binary.
We can rewrite ex1 as follows:
cd examples/ex1
make
ddisasm ex --asm ex.s
gcc ex.s -o ex_rewritten
The directory tests/ also contains a script test_small.sh for
rewriting the examples in /examples with different compilers and
optimization flags.
Please read the DDisasm Code of Conduct.
Please follow the Code Requirements in gtirb/CONTRIBUTING.
ddisasm generates the following AuxData tables:
| Key | Type | Purpose |
|---|---|---|
| comments | std::map<gtirb::Offset, std::string> |
Per-instruction comments. |
| functionEntries | std::map<gtirb::UUID, std::set<gtirb::UUID>> |
UUIDs of the blocks that are entry points of functions. |
| functionBlocks | std::map<gtirb::UUID, std::set<gtirb::UUID>> |
UUIDs of the blocks that belong to each function. |
| symbolForwarding | std::map<gtirb::UUID, gtirb::UUID> |
Map from symbols to other symbols. This table is used to forward symbols due to relocations or due to the use of plt and got tables. |
| encodings | std::map<gtirb::UUID, std::string> |
Map from (typed) data objects to the encoding of the data, expressed as a std::string containing an assembler encoding specifier: "string", "uleb128" or "sleb128". |
| elfSectionProperties | std::map<gtirb::UUID, std::tuple<uint64_t, uint64_t>> |
Map from section UUIDs to tuples with the ELF section types and flags. |
| cfiDirectives | std::map<gtirb::Offset, std::vector<std::tuple<std::string, std::vector<int64_t>, gtirb::UUID>>> |
Map from Offsets to vector of cfi directives. A cfi directive contains: a string describing the directive, a vector of numeric arguments, and an optional symbolic argument (represented with the UUID of the symbol). |
| libraries | std::vector<std::string> |
Names of the libraries that are needed. |
| libraryPaths | std::vector<std::string> |
Paths contained in the rpath of the binary. |
| padding | std::map<gtirb::Addr, uint64_t> |
Address where there is padding and the length of the padding in bytes. |
| SCCs | std::map<gtirb::UUID, int64_t> |
The intra-procedural SCC identifier of each block |