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Graphene Library OS with Intel SGX Support
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.. image:: https://readthedocs.org/projects/graphene/badge/?version=latest
   :target: http://graphene.readthedocs.io/en/latest/?badge=latest
   :alt: Documentation Status

*A Linux-compatible Library OS for Multi-Process Applications*

.. This is not |nbsp|, because that is in rst_prolog in conf.py, which GitHub
   cannot parse. GitHub doesn't appear to use it correctly anyway...
.. |_| unicode:: 0xa0
   :trim:

What is Graphene?
=================

Graphene is a lightweight guest OS, designed to run a single application with minimal host
requirements.  Graphene can run applications in an isolated environment with benefits comparable to
running a complete OS in a virtual machine -- including guest customization, ease of porting to
different OSes, and process migration.

Graphene supports native, unmodified Linux applications on any platform. Currently, Graphene runs on
Linux, FreeBSD and Intel SGX enclaves on Linux platforms.

With Intel SGX support, Graphene can secure a |_| critical application in a |_| hardware-encrypted
memory region. Graphene can protect applications from a |_| malicious system stack with minimal
porting effort.

Our papers describe the motivation, design choices, and measured performance of Graphene:

- `EuroSys 2014 <http://www.cs.unc.edu/~porter/pubs/tsai14graphene.pdf>`
- `ATC 2017 <http://www.cs.unc.edu/~porter/pubs/graphene-sgx.pdf>`


How to build Graphene?
======================

Graphene consists of three parts:

- An instrumented GNU C Library
- The Library OS itself (a shared library named ``libsysdb.so``, called the "shim" in our source code)
- The Platform Adaptation Layer, or PAL, (a shared library named ``libpal.so``)

Graphene currently only works on the x86_64 architecture.  Graphene is currently tested on Ubuntu
16.04 and 18.04 (both server and desktop version), along with Linux kernel versions 3.x/4.x.  We
recommend building and installing Graphene on the same host platform.  If you find problems with
Graphene on other Linux distributions, please contact us with a detailed bug report.

Run the following command on Ubuntu to install dependencies for Graphene::

    sudo apt-get install -y build-essential autoconf gawk bison

For building Graphene for SGX, run the following command in addition::

    sudo apt-get install -y python-protobuf libprotobuf-c-dev protobuf-c-compiler

To run tests locally, you also need the python3-pytest package::

    sudo apt-get install -y python3-pytest

To build Graphene, simply run the following commands in the root of the
source tree::

    git submodule update --init -- Pal/src/host/Linux-SGX/sgx-driver/
    make

Each part of Graphene can be built separately in the subdirectories.

To build Graphene with debug symbols, run ``make DEBUG=1``
instead of ``make``. To specify custom mirrors for downloading the GLIBC
source, use ``make GLIBC_MIRRORS=...``.

To build with ``-Werror``, run ``make WERROR=1``.

Building with kernel-level sandboxing (optional)
------------------------------------------------

This feature is marked as EXPERIMENTAL and no longer exists on the master branch.

Building with Intel SGX Support
-------------------------------

Prerequisites
^^^^^^^^^^^^^

1. Generate signing keys

   A 3072-bit RSA private key (PEM format) is required for signing the manifest.
   If you don't have a private key, create it with the following command::

      openssl genrsa -3 -out enclave-key.pem 3072

   You can either place the generated enclave key in the default path,
   ``host/Linux-SGX/signer/enclave-key.pem``, or specify the key's location through
   the environment variable ``SGX_SIGNER_KEY``.

   After signing the application's manifest, users may ship the application and Graphene binaries,
   along with an SGX-specific manifest (.manifest.sgx extension), the signature (.sig extension),
   and the aesmd init token (.token extension) to execute on another SGX-enabled host.

2. Install the Intel SGX SDK and driver

   The Intel SGX Linux SDK is required to compile and run Graphene on SGX. Download
   and install it from the official Intel GitHub repositories:

   - <https://github.com/01org/linux-sgx>
   - <https://github.com/01org/linux-sgx-driver>

3. Build and install the Graphene SGX driver
   A Graphene-specific Linux driver must also be installed before running Graphene in
   an SGX environment. Simply run the following commands to build the driver::

      cd Pal/src/host/Linux-SGX/sgx-driver
      make
      # The console will be prompted to ask for the path of Intel SGX driver code
      sudo ./load.sh
      sudo sysctl vm.mmap_min = 0

   We note that this last command is a tempoarary work-around for some issues with the Intel SGX
   driver.  This is an inadvisable configuration for production systems.  We hope to remove this
   step in a future version of Graphene, once the SGX driver is upstreamed to Linux.

Building Graphene-SGX
^^^^^^^^^^^^^^^^^^^^^

To build Graphene with Intel SGX support, in the root directory of Graphene repo, run the following
command::

   make SGX=1

To build with debug symbols, instead run the command::

   make SGX=1 DEBUG=1

Running ``make SGX=1`` in the test or regression directory will automatically generate the required
manifest signatures (.sig files).

Run Built-in Examples in Graphene-SGX
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

There are a few built-in examples under ``LibOS/shim/test/``. The "native"
folder includes a |_| rich set of C |_| programs and "apps" folder includes
a |_| few tested applications, such as GCC, Python, and Apache.

1. Build and run a |_| ``helloworld`` program with Graphene-SGX

   - go to LibOS/shim/test/native, build the enclaves via the command::

      make SGX=1

     This command will build enclaves for all the programs in the folder

   - Generate the token from aesmd service, via the command::

      make SGX=1 sgx-tokens

   - Run a helloworld program with Graphene-SGX::

      SGX=1 ./pal_loader helloworld

     or::

      ./pal_loader SGX helloworld

2. Build and run the Python ``helloworld.py`` script in Graphene-SGX

   - go to LibOS/shim/test/apps/python, and build the enclave::

      make SGX=1

   - Generate a launch token from the aesmd service::

      make SGX=1 sgx-tokens

   - Run ``helloworld.py`` script with Graphene-SGX via::

      SGX=1 ./python.manifest.sgx scripts/helloworld.py

Including Application Test Cases
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

To add the application test cases, issue the following command from the root
of the source tree::

   git submodule update --init -- LibOS/shim/test/apps/

Testing the remote attestation feature
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

To enable tests for the built-in remote attestation feature for Graphene-SGX, obtain a SPID
and a subscription key (can be linkable or unlinkable) from the Intel API Portal:
<https://api.portal.trustedservices.intel.com/EPID-attestation>.

Specify the SPID, subscription key, and the type of the SPID/key in the manifest::

    sgx.ra_client_spid = <SPID>
    sgx.ra_client_key = <KEY>
    sgx.ra_client_linkable = 1 # or 0 if the SPID/key is unlinkable (default)

If the remote attestation feature is enabled, Graphene-SGX will terminate if the platform
is not successfully verified by the Intel Attestation Service (IAS). The feature ensures that
Graphene-SGX only executes on genuine, up-to-date SGX hardware.


To enable remote attestation tests in ``Pal/regression``, specify the following variables::

    cd PAL/regression
    make SGX=1 RA_CLIENT_SPID=<SPID> RA_CLIENT_KEY=<KEY>
    make SGX=1 sgx-tokens


If you receive a ``GROUP_OUT_OF_DATE`` status from IAS, this status indicates that your CPU
is out of date and can be vulnerable to hardware attacks. If you wish to bypass this error,
you can specify the following option in the manifest::

    sgx.ra_accept_group_out_of_date = 1

*Security advisories:*

- ``GROUP_OUT_OF_DATE`` may indicate that the firmware (microcode) of you CPU is not updated
  according to INTEL-SA-00233 (Load/store data sampling) and INTEL-SA-00161 (L1 terminal fault).
  It is recommended that you keep the BIOS of your platform up-to-date.

- If you receive status ``CONFIGURATION_NEEDED`` from the IAS after updating your BIOS, you may
  need to disable hyperthreading in your BIOS to mitigate L1 terminal fault.

How to run an application in Graphene?
======================================

Graphene library OS uses the PAL (``libpal.so``) as a loader to bootstrap applications in the
library OS. To start Graphene, PAL (``libpal.so``) will have to be run as an executable, with the
name of the program, and a |_| "manifest file" (per-app configuration) given from the command
line. Graphene provides three options for specifying the programs and manifest files:

- option 1 (automatic manifest)::

   [PATH TO Runtime]/pal_loader [PROGRAM] [ARGUMENTS]...
   (Manifest file: "[PROGRAM].manifest" or "manifest")

- option 2 (given manifest)::

   [PATH TO Runtime]/pal_loader [MANIFEST] [ARGUMENTS]...

- option 3 (manifest as a script)::

   [PATH TO MANIFEST]/[MANIFEST] [ARGUMENTS]...
   (Manifest must have "#![PATH_TO_PAL]/libpal.so" as the first line)

Running an application requires some minimal configuration in the application's manifest file.  A
|_| sensible manifest file will include paths to the library OS and other libraries the application
requires; environment variables, such as ``LD_LIBRARY_PATH``; and file systems to be mounted.

Here is an example manifest file::

    loader.preload = file:LibOS/shim/src/libsysdb.so
    loader.env.LD_LIBRAY_PATH = /lib
    fs.mount.libc.type = chroot
    fs.mount.libc.path = /lib
    fs.mount.libc.uri = file:[relative path to Graphene root]/Runtime

More examples can be found in the test directories (``LibOS/shim/test``). We
have also tested several applications, such as GCC, Bash, and Apache.
The manifest files for these applications are provided in the
individual directories under ``LibOS/shim/test/apps``.

For the full documentation of the Graphene manifest syntax, see the `Graphene
documentation <https://graphene.readthedocs.io/>`_.

Contact
=======

For any questions or bug reports, please send an email to
<support@graphene-project.io> or post an issue on our GitHub repository:
<https://github.com/oscarlab/graphene/issues>.

Our mailing list is publicly archived `here
<https://groups.google.com/forum/#!forum/graphene-support>`_.
