Building Qubes from scratch

We have a fully automated build system for Qubes, that downloads, builds and packages all the Qubes components, and finally should spit out a ready-to-use installation ISO.

In order to use it one should use an rpm-based distro, like Fedora :) and should ensure the following packages are installed:

  • sudo
  • gpg
  • git
  • createrepo
  • rpm-build
  • make
  • wget
  • rpmdevtools
  • python-sh
  • dialog
  • rpm-sign
  • dpkg-dev
  • debootstrap
  • PyYAML

Unusually one can install those packages by just issuing:

sudo dnf install gpg git createrepo rpm-build make wget rpmdevtools python-sh dialog rpm-sign dpkg-dev debootstrap PyYAML

The build system creates build environments in chroots and so no other packages are needed on the host. All files created by the build system are contained within the qubes-builder directory. The full build requires some 25GB of free space, so keep that in mind when deciding where to place this directory.

The build system is configured via builder.conf file – one should copy the attached builder.conf.default, and modify it as needed, e.g.:

cp example-configs/qubes-os-master.conf builder.conf 
# edit the builder.conf file and set the following variables: 
NO_SIGN=1

One additional useful requirement is that ‘sudo root’ work without any prompt, which is default on most distros (e.g. ‘sudo bash’ brings you the root shell without asking for any password). This is important as the builder needs to switch to root and then back to user several times during the build process.

Additionally, if building with signing enabled (so NO_SIGN is not set), one must adjust ~/.rpmmacro file so that it point to the GPG key used for package signing, e.g.:

%_signature gpg
%_gpg_path /home/user/.gnupg
%_gpg_name AC1BF9B3  # <-- Key ID used for signing

It is also recommended to use an empty passphrase for the private key used for signing. Contrary to a popular belief, this doesn’t affect your key or sources security – if somebody compromised your system, then the game is over, whether you use additional passphrase for the key or not.

So, to build Qubes one would do:

# Import the Qubes master key 
gpg --recv-keys 0xDDFA1A3E36879494

# Verify its fingerprint, set as 'trusted'. 
# This is described here: 
# https://www.qubes-os.org/doc/VerifyingSignatures

wget https://keys.qubes-os.org/keys/qubes-developers-keys.asc
gpg --import qubes-developers-keys.asc 

git clone git://github.com/QubesOS/qubes-builder.git qubes-builder 
cd qubes-builder 

# Verify its integrity:
git tag -v `git describe`

cp example-configs/qubes-os-master.conf builder.conf 
# edit the builder.conf file and set the following variables: 
# NO_SIGN="1"

# Download all components:

make get-sources

# And now to build all Qubes rpms (this will take a few hours): 

make qubes 

# ... and then to build the ISO 

make iso 

And this should produce a shiny new ISO.

You can also build selected component separately. Eg. to compile only gui virtualization agent/daemon:

make gui-daemon

Full list you can get from make help. For advanced use and preparing sources for use with QubesBuilder take a look at doc directory in QubesBuilder or QubesBuilderDetails page.

Making customized build

Manual source modification

If you want to somehow modify sources, you can also do it, here are some basic steps:

  1. Download qubes-builder as described above (if you want to use marmarek’s branches, you should also download qubes-builder from his repo - replace ‘QubesOS’ with ‘marmarek’ in above git clone command)
  2. Edit builder.conf (still the same as above), some useful additions:
    • You can also set GIT_PREFIX=”marmarek/qubes-“ to use my repo instead of “mainstream” - it contains newer (but less tested) versions
  3. Download unmodified sources

    make get-sources
    
  4. Make your modifications here

  5. Build the Qubes make qubes actually is just meta target which build all required components in correct order. List of components is configured in builder.conf. You can also check the current value at the end of make help, or using make build-info.

  6. get-sources is already done, so continue with the next one. You can skip sign-all if you’ve disabled signing

     make vmm-xen core-admin linux-kernel gui-daemon template desktop-linux-kde installer-qubes-os manager linux-dom0-updates
    
  7. build iso installation image

    make iso
    

Code verification keys management

QubesBuilder by default verifies signed tags on every downloaded code. Public keys used for that are stored in keyrings/git. By default Qubes developers’ keys are imported automatically, but if you need some additional keys (for example your own), you can add them using:

GNUPGHOME=$PWD/keyrings/git gpg --import /path/to/key.asc
GNUPGHOME=$PWD/keyrings/git gpg --edit-key ID_OF_JUST_IMPORTED_KEY
# here use "trust" command to set key fully or ultimately trusted - only those keys are accepted by QubesBuilder

All Qubes developers’ keys are signed by the Qubes Master Signing Key (which is set as ultimately trusted key), so are trusted automatically.

If you are the owner of Master key and want to revoke such signature, use the revsig gpg key edit command and update the key in qubes-developers-keys.asc - now the key will be no longer trusted (unless manually set as such).