OCCAM: Object Culling and Concretization for Assurance Maximization
C++ Python Protocol Buffer Shell Makefile Ruby
Latest commit bbf4eee Feb 14, 2017 @ashish-gehani committed on GitHub Merge pull request #20 from SRI-CSL/master


PyPI version Build Status


OCCAM currently works fine on Linux, OS X, and FreeBSD. You will need an installation of llvm-3.5. If you need to generate application bitcode, you will want to install wllvm, either from the the pip package or the GitHub repository.

Building and Installing

Set where OCCAM's library will be stored:

  export OCCAM_HOME={path to location in your home directory}

Point to your LLVM's location, if non-standard:

  export LLVM_HOME=/usr/local/llvm-3.5
  export LLVM_CONFIG=llvm-config-3.5

Set where system libraries, including Google Protocol Buffers, are located:

  export LD_FLAGS='-L/usr/local/lib'

Build and install OCCAM with:

  make install

Detailed instructions for Ubuntu 14.04 can be gleaned from bootstrap.sh.


You can choose to record logs from the OCCAM tool by setting the following variables:

  export OCCAM_LOGFILE={absolute path to log location}

Using razor

razor is a pip package that relies on the same dynamic library as occam, so you should first build and install occam as described above. razor provides the commandline tool slash. You can either install razor you can from this repository, or you can just do a

pip install razor

To install an editable version from this repository:

make -f Makefile develop

This may require sudo priviliges. Either way you can now use slash:

slash [--work-dir=<dir>]  [--force] [--no-strip] [--no-specialize] <manifest>

slash also accepts the following new command line option:


which will prevent any inter-module specializations.

To function correctly slash calls LLVM tools such as opt and clang++. These should be available in your PATH, and be the currently supported version (3.5). Like wllvm, slash, will pay attention to the environment variables LLVM_OPT_NAME and LLVM_CXX_NAME if your version of these tools are adorned with suffixes.

The Manifest(o)

The manifest for slash should be valid JSON. The following keys have meaning:

  • main : a path to the bitcode module containing the main entry point.

  • modules: a list of paths to the other bitcode modules needed.

  • binary : the name of the desired executable.

  • native_libs : a list of flags (-lm, -lc, -lpthread) or paths to native objects (.o, .a, .so, .dylib)

  • ldflags: a list of linker flags such as --static, --nostdlib

  • args : the list of arguments you wish to specialize in the main of main.

As an example, (see examples/linux/apache), to previrtualize apache:

{ "main" : "httpd.bc"
, "binary"  : "httpd_slashed"
, "modules"    : ["libapr-1.so.bc", "libaprutil-1.so.bc", "libpcre.so.bc"]
, "native_libs" : ["-lcrypt", "-ldl", "-lpthread"]
, "args"    : ["-d", "/var/www"]
, "name"    : "httpd"

Another example, (see examples/linux/musl_nweb), specializes nweb with musl libc.c:

{ "main" :  "nweb.o.bc"
, "binary"  : "nweb_razor"
, "modules"    : ["libc.a.bc"]
, "native_libs" : ["crt1.o", "libc.a"]
, "ldflags" : ["-static", "-nostdlib"]
, "args"    : ["8181", "./root"]
, "name"    : "nweb"