Kushal Das4

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Building wheels and Debian packages for SecureDrop on Qubes OS

For the last couple of months, the SecureDrop team is working on a new set of applications + system for the journalists, which are based on Qubes OS, and desktop application written particularly for Qubes. A major portion of the work is on the Qubes OS part, where we are setting up the right templateVMs and AppVMs on top of those templateVMs, setting up the qrexec services and right configuration to allow/deny services as required.

The other major work was to develop a proxy service (on top of Qubes qrexec service) which will allow our desktop application (written in PyQt) to talk to a SecureDrop server. This part finally gets into two different Debian packages.

  1. The securedrop-proxy package: which contains only the proxy tool
  2. The securedrop-client: which contains the Python SDK (to talk to the server using proxy) and desktop client tool

The way to build SecureDrop server packages

The legacy way of building SecureDrop server side has many steps and also installs wheels into the main Python site-packages. Which is something we plan to remove in future. While discussing about this during PyCon this year, Donald Stufft suggested to use dh-virtualenv. It allows to package a virtualenv for the application along with the actual application code into a Debian pacakge.

The new way of building Debian packages for the SecureDrop on Qubes OS

Creating requirements.txt file for the projects

We use pipenv for the development of the projects. pipenv lock -r can create a requirements.txt, but, it does not content any sha256sums. We also wanted to make sure that doing these steps become much easier. We have added a makefile target in our new packaging repo, which will first create the standard requirements.txt and then it will try to find the corresponding binary wheel sha256sums from a list of wheels+sha256sums, and before anything else, it verifies the list (signed with developers’ gpg keys).

PKG_DIR=~/code/securedrop-proxy make requirements

If it finds any missing wheels (say new dependency or updated package version), it informs the developer, the developer then can use another makefile target to build the new wheels, the new wheels+sources do get synced to our simple index hosted on s3. The hashes of the wheels+sources also get signed and committed into the repository. Then, the developer retries to create the requirements.txt for the project.

Building the package

We also have makefile targets to build the Debian package. It actually creates a directory structure (only in parts) like rpmbuild does in home directory, and then copies over the source tarball, untars, copies the debian directory from the packaging repository, and then reverifies each hashes in the project requirements file with the current signed (and also verified) list of hashes. If everything looks good, then it goes to build the final Debian package. This happens by the following environment variable exported in the above mention script.

DH_PIP_EXTRA_ARGS="--no-cache-dir --require-hashes"

Our debian/rules files make sure that we use our own packaging index for building the Debian package.

#!/usr/bin/make -f

%:
	dh $@ --with python-virtualenv --python /usr/bin/python3.5 --setuptools --index-url https://dev-bin.ops.securedrop.org/simple

For example, the following command will build the package securedrop-proxy version 0.0.1.

PKG_PATH=~/code/securedrop-proxy/dist/securedrop-proxy-0.0.1.tar.gz PKG_VERSION=0.0.1 make securedrop-proxy

The following image describes the whole process.

We would love to get your feedback and any suggestions to improve the whole process. Feel free to comment in this post, or by creating issues in the corresponding Github project.

PyPI and gpg signed packages

Yesterday night, on #pypa IRC channel, asked about uploading detached gpg signatures for the packages. According to , twine did not upload the signature, even with passing -s as an argument. I tried to do the same in test.pypi.org, and at first, I felt the same, as the package page was not showing anything. As I started reading the source of twine to figure out what is going on, I found that it uploads the signature as part of the metadata of package. The JSON API actually showed that the release is signed. Later, and explained that we just have to add .asc at the end of the url of the package to download the detached signature.

During the conversation, mentioned that only 4% of the total packages are actually gpg signed. And gpg is written in C and also a GPL licensed software, so, it can not be packaged inside of CPython (as pip is packaged inside of CPython). The idea of a future PyPI where all packages must be signed (how will still have to discussed) was also discussed in the IRC channel. We also get to know that we can delete any file/relase from PyPI, but, we can not reload those files again. One has to do a new release. This is also very important incase you want to upload signatures, you will have to do that at the time of uploading the package.

also wrote about the idea of signing the packages a few years ago.