Development workflow

A workflow for developing Qubes OS+

First things first, setup QubesBuilder. This guide assumes you’re using qubes-builder to build Qubes.

Repositories and committing Code

Qubes is split into a bunch of git repos. These are all contained in the qubes-src directory under qubes-builder. Subdirectories there are separate components, stored in separate git repositories.

The best way to write and contribute code is to create a git repo somewhere (e.g., github) for the repo you are interested in editing (e.g., qubes-manager, core-agent-linux, etc). To integrate your repo with the rest of Qubes, cd to the repo directory and add your repository as a remote in git

Example:

$ cd qubes-builder/qubes-src/qubes-manager
$ git remote add abel git@github.com:abeluck/qubes-manager.git

You can then proceed to easily develop in your own branches, pull in new commits from the dev branches, merge them, and eventually push to your own repo on github.

When you are ready to submit your changes to Qubes to be merged, push your changes, then create a signed git tag (using git tag -s). Finally, send a letter to the Qubes listserv describing the changes and including the link to your repository. You can also create pull request on github. Don’t forget to include your public PGP key you use to sign your tags.

Kernel-specific notes

Prepare fresh version of kernel sources, with Qubes-specific patches applied

In qubes-builder/qubes-src/linux-kernel:

make prep

The resulting tree will be in kernel-<VERSION>/linux-<VERSION>:

ls -ltrd kernel*/linux*

drwxr-xr-x 23 user user 4096 Nov  5 09:50 kernel-3.4.18/linux-3.4.18
drwxr-xr-x  6 user user 4096 Nov 21 20:48 kernel-3.4.18/linux-obj

Go to the kernel tree and update the version

In qubes-builder/qubes-src/linux-kernel:

cd kernel-3.4.18/linux-3.4.18

Changing the config

In kernel-3.4.18/linux-3.4.18:

cp ../../config .config
make oldconfig

Now change the configuration. For example, in kernel-3.4.18/linux-3.4.18:

make menuconfig

Copy the modified config back into the kernel tree:

cp .config ../../../config

Patching the code

TODO: describe the workflow for patching the code, below are some random notes, not working well

ln -s ../../patches.xen
export QUILT_PATCHES=patches.xen
export QUILT_REFRESH_ARGS="-p ab --no-timestamps --no-index"
export QUILT_SERIES=../../series-pvops.conf

quilt new patches.xen/pvops-3.4-0101-usb-xen-pvusb-driver-bugfix.patch
quilt add drivers/usb/host/Kconfig drivers/usb/host/Makefile \
        drivers/usb/host/xen-usbback/* drivers/usb/host/xen-usbfront.c \
        include/xen/interface/io/usbif.h

*edit something*

quilt refresh
cd ../..
vi series.conf

Building RPMs

TODO: Is this step generic for all subsystems?

Now it is a good moment to make sure you have changed kernel release name in rel file. For example, if you change it to ‘1debug201211116c’ the resulting RPMs will be named ‘kernel-3.4.18-1debug20121116c.pvops.qubes.x86_64.rpm’. This will help distinguish between different versions of the same package.

You might want to take a moment here to review (git diff, git status), commit your changes locally.

To actually build RPMs, in qubes-builder:

make linux-kernel

RPMs will appear in qubes-src/linux-kernel/pkgs/fc20/x86_64:

-rw-rw-r-- 1 user user 42996126 Nov 17 04:08 kernel-3.4.18-1debug20121116c.pvops.qubes.x86_64.rpm
-rw-rw-r-- 1 user user 43001450 Nov 17 05:36 kernel-3.4.18-1debug20121117a.pvops.qubes.x86_64.rpm
-rw-rw-r-- 1 user user  8940138 Nov 17 04:08 kernel-devel-3.4.18-1debug20121116c.pvops.qubes.x86_64.rpm
-rw-rw-r-- 1 user user  8937818 Nov 17 05:36 kernel-devel-3.4.18-1debug20121117a.pvops.qubes.x86_64.rpm
-rw-rw-r-- 1 user user 54490741 Nov 17 04:08 kernel-qubes-vm-3.4.18-1debug20121116c.pvops.qubes.x86_64.rpm
-rw-rw-r-- 1 user user 54502117 Nov 17 05:37 kernel-qubes-vm-3.4.18-1debug20121117a.pvops.qubes.x86_64.rpm

Useful QubesBuilder commands

1. make check - will check if all the code was committed into repository and if all repository are tagged with signed tag.
2. make show-vtags - show version of each component (based on git tags) - mostly useful just before building ISO. Note: this will not show version for components containing changes since last version tag.
3. make push - push change from all repositories to git server. You must set proper remotes (see above) for all repositories first.
4. make prepare-merge - fetch changes from remote repositories (can be specified on commandline via GIT_SUBDIR or GIT_REMOTE vars), (optionally) verify tags and show the changes. This do not merge the changes - there are left for review as FETCH_HEAD ref. You can merge them using git merge FETCH_HEAD (in each repo directory). Or make do-merge to merge all of them.

Copying Code to dom0

When developing it is convenient to be able to rapidly test changes. Assuming you’re developing Qubes on Qubes, you should be working in a special VM for Qubes and occasionally you will want to transfer code or RPMs back to dom0 for testing.

Here are some handy scripts Marek has shared to facilitate this.

You may also like to run your test environment on separate machine.

Syncing dom0 files

TODO: edit this script to be more generic

#!/bin/sh

set -x
set -e

QUBES_PY_DIR=/usr/lib64/python2.6/site-packages/qubes
QUBES_PY=$QUBES_PY_DIR/qubes.py
QUBESUTILS_PY=$QUBES_PY_DIR/qubesutils.py

qvm-run -p qubes-devel 'cd qubes-builder/qubes-src/core/dom0; tar c qmemman/qmemman*.py qvm-core/*.py qvm-tools/* misc/vm-template-hvm.conf misc/qubes-start.desktop ../misc/block-snapshot aux-tools ../qrexec' |tar xv
cp $QUBES_PY qubes.py.bak$$
cp $QUBESUTILS_PY qubesutils.py.bak$$
cp /etc/xen/scripts/block-snapshot block-snapshot.bak$$
sudo cp qvm-core/qubes.py $QUBES_PY
sudo cp qvm-core/qubesutils.py $QUBESUTILS_PY
sudo cp qvm-core/guihelpers.py $QUBES_PY_DIR/
sudo cp qmemman/qmemman*.py $QUBES_PY_DIR/
sudo cp misc/vm-template-hvm.conf /usr/share/qubes/
sudo cp misc/qubes-start.desktop /usr/share/qubes/
sudo cp misc/block-snapshot /etc/xen/scripts/
sudo cp aux-tools/qubes-dom0-updates.cron /etc/cron.daily/
# FIXME(Abel Luck): I hope to

Apply qvm-tools

TODO: make it more generic

#!/bin/sh

BAK=qvm-tools.bak$$
mkdir -p $BAK
cp -a /usr/bin/qvm-* /usr/bin/qubes-* $BAK/
sudo cp qvm-tools/qvm-* qvm-tools/qubes-* /usr/bin/

Copy from dom0 to an appvm

#/bin/sh
#
# usage ./cp-domain <vm_name> <file_to_copy>
#
domain=$1
file=$2
fname=`basename $file`

qvm-run $domain 'mkdir /home/user/incoming/dom0 -p'
cat $file| qvm-run --pass-io $domain "cat > /home/user/incoming/dom0/$fname"

Git connection between VMs

Sometimes it’s useful to transfer git commits between VMs. You can use git format-patch for that and simply copy the files. But you can also setup custom qrexec service for it.

Below example assumes that you use builder-RX directory in target VM to store sources in qubes-builder layout (where X is some number). Make sure that all the scripts are executable.

Service file (save in /usr/local/etc/qubes-rpc/local.Git in target VM):

#!/bin/sh

exec 2>/tmp/log2

read service rel repo
echo "Params: $service $rel $repo" >&2
# Adjust regexps if needed
echo "$repo" | grep -q '^[A-Za-z0-9-]\+$' || exit 1
echo "$rel" | grep -q '^[0-9.]\+$' || exit 1
path="/home/user/builder-R$rel/qubes-src/$repo"
if [ "$repo" = "builder" ]; then
    path="/home/user/builder-R$rel"
fi
case $service in
    git-receive-pack|git-upload-pack)
        echo "starting $service $path" >&2
        exec $service $path
        ;;
    *)
        echo "Unsupported service: $service" >&2
        ;;
esac

Client script (save in ~/bin/git-qrexec in source VM):

#!/bin/sh

VMNAME=$1

(echo $GIT_EXT_SERVICE $2 $3; exec cat) | qrexec-client-vm $VMNAME local.Git

You will also need to setup qrexec policy in dom0 (/etc/qubes-rpc/policy/local.Git).

Usage:

[user@source core-agent-linux]$ git remote add testbuilder "ext::git-qrexec testbuilder 3 core-agent-linux"
[user@source core-agent-linux]$ git push testbuilder master

You can create ~/bin/add-remote script to ease adding remotes:

#!/bin/sh

[ -n "$1" ] || exit 1

if [ "$1" = "tb" ]; then
    git remote add $1 "ext::git-qrexec testbuilder 3 `basename $PWD`"
    exit $?
fi

git remote add $1 git@github.com:$1/qubes-`basename $PWD`

It should be executed from component top level directory. This script takes one argument - remote name. If it is tb, then it creates qrexec-based git remote to testbuilder VM. Otherwise it creates remote pointing at github account of the same name. In any case it points at repository matching current directory name.

Sending packages to different VM

Other useful script(s) can be used to setup local package repository hosted in some VM. This way you can keep your development VM behind firewall, while having an option to expose some yum/apt repository to the local network (to have them installed on test machine).

To achieve this goal, a dummy repository can be created, which instead of populating metadata locally, will upload the packages to some other VM and trigger repository update there (using qrexec). You can use unstable repository flavor, because there is no release managing rules bundled (unlike current and current-testing).

RPM packages - yum repo

In source VM, grab linux-yum repository (below is assumed you’ve made it in ~/repo-yum-upload directory) and replace update_repo.sh script with:

#!/bin/sh

VMNAME=repo-vm

set -e
qvm-copy-to-vm $VMNAME $1
# remove only files, leave directory structure
find -type f -name '*.rpm' -delete
# trigger repo update
qrexec-client-vm $VMNAME local.UpdateYum

In target VM, setup actual yum repository (also based on linux-yum, this time without modifications). You will also need to setup some gpg key for signing packages (it is possible to force yum to install unsigned packages, but it isn’t possible for qubes-dom0-update tool). Fill ~/.rpmmacros with key description:

%_gpg_name Test packages signing key

Then setup local.UpdateYum qrexec service (/usr/local/etc/qubes-rpc/local.UpdateYum):

#!/bin/sh

if [ -z "$QREXEC_REMOTE_DOMAIN" ]; then
    exit 1
fi

real_repository=/home/user/linux-yum
incoming=/home/user/QubesIncoming/$QREXEC_REMOTE_DOMAIN

find $incoming -name '*.rpm' |xargs rpm -K |grep -iv pgp |cut -f1 -d: |xargs -r setsid -w rpm --addsign 2>&1

rsync -lr --remove-source-files $incoming/ $real_repository
cd $real_repository
export SKIP_REPO_CHECK=1
if [ -d $incoming/r3.1 ]; then
    ./update_repo-unstable.sh r3.1
fi

if [ -d $incoming/r3.0 ]; then
    ./update_repo-unstable.sh r3.0
fi

if [ -d $incoming/r2 ]; then
    ./update_repo-unstable.sh r2
fi
find $incoming -type d -empty -delete
exit 0

Of course you will also need to setup qrexec policy in dom0 /etc/qubes-rpc/policy/local.UpdateYum.

If you want to access the repository from network, you need to setup HTTP server serving it, and configure the system to let other machines actually reach this HTTP server. You can use for example using port forwarding or setting up Tor hidden service. Configuration details of those services are outside of the scope of this page.

Usage: setup builder.conf in source VM to use your dummy-uploader repository:

LINUX_REPO_BASEDIR = ../../repo-yum-upload/r3.1

Then use make update-repo-unstable to upload the packages. You can also specify selected components on command line, then build them and upload to the repository:

make COMPONENTS="core-agent-linux gui-agent-linux linux-utils" qubes update-repo-unstable

On the test machine, add yum repository (/etc/yum.repos.d) pointing at just configured HTTP server. For example:

[local-test]
name=Test
baseurl=http://local-test.lan/linux-yum/r$releasever/unstable/dom0/fc20

Remember to also import gpg public key using rpm --import.

Deb packages - Apt repo

Steps are mostly the same as in the case of yum repo. The only details that differ:

• use linux-deb instead of linux-yum as a base - both in source and target VM
• use different update_repo.sh script in source VM (below)
• use local.UpdateApt qrexec service in target VM (code below)
• in target VM additionally place update-local-repo.sh script in repository dir (code below)

update_repo.sh script:

#!/bin/sh

set -e

current_release=$1
VMNAME=repo-vm

qvm-copy-to-vm $VMNAME $1
find $current_release -type f -name '*.deb' -delete
rm -f $current_release/vm/db/*
qrexec-client-vm $VMNAME local.UpdateApt

local.UpdateApt service code (/usr/local/etc/qubes-rpc/local.UpdateApt in repo-serving VM):

#!/bin/sh

if [ -z "$QREXEC_REMOTE_DOMAIN" ]; then
    exit 1
fi

incoming=/home/user/QubesIncoming/$QREXEC_REMOTE_DOMAIN

rsync -lr --remove-source-files $incoming/ /home/user/linux-deb/
cd /home/user/linux-deb
export SKIP_REPO_CHECK=1
if [ -d $incoming/r3.1 ]; then
    for dist in `ls r3.1/vm/dists`; do
        ./update-local-repo.sh r3.1/vm $dist
    done
fi

if [ -d $incoming/r3.0 ]; then
    for dist in `ls r3.0/vm/dists`; do
        ./update-local-repo.sh r3.0/vm $dist
    done
fi

if [ -d $incoming/r2 ]; then
    for dist in `ls r2/vm/dists`; do
        ./update-local-repo.sh r2/vm $dist
    done
fi
find $incoming -type d -empty -delete
exit 0

update-local-repo.sh:

#!/bin/sh

set -e

# Set this to your local repository signing key
SIGN_KEY=01ABCDEF

[ -z "$1" ] && { echo "Usage: $0 <repo> <dist>"; exit 1; }

REPO_DIR=$1
DIST=$2

if [ "$DIST" = "wheezy-unstable" ]; then
    DIST_TAG=deb7
elif [ "$DIST" = "jessie-unstable" ]; then
    DIST_TAG=deb8
elif [ "$DIST" = "stretch-unstable" ]; then
    DIST_TAG=deb9
fi

pushd $REPO_DIR
mkdir -p dists/$DIST/main/binary-amd64
dpkg-scanpackages --multiversion --arch "*$DIST_TAG*" . > dists/$DIST/main/binary-amd64/Packages
gzip -9c dists/$DIST/main/binary-amd64/Packages > dists/$DIST/main/binary-amd64/Packages.gz
cat > dists/$DIST/Release <<EOF
Label: Test repo
Suite: $DIST
Codename: $DIST
Date: `date -R`
Architectures: amd64
Components: main
SHA1:
EOF
function calc_sha1() {
    f=dists/$DIST/$1
    echo -n " "
    echo -n `sha1sum $f|cut -d' ' -f 1` ""
    echo -n `stat -c %s $f` ""
    echo $1
}
calc_sha1 main/binary-amd64/Packages >> dists/$DIST/Release

rm -f $DIST/Release.gpg
rm -f $DIST/InRelease
gpg -abs -u "$SIGN_KEY" \
    < dists/$DIST/Release > dists/$DIST/Release.gpg
gpg -a -s --clearsign -u "$SIGN_KEY" \
    < dists/$DIST/Release > dists/$DIST/InRelease
popd

if [ `id -u` -eq 0 ]; then
    chown -R --reference=$REPO_DIR $REPO_DIR
fi

Usage: add this line to /etc/apt/sources.list on test machine (adjust host and path):

deb http://local-test.lan/linux-deb/r3.1 jessie-unstable main