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Firejail

Firejail is a lightweight security tool intended to protect a Linux system by setting up a restricted environment for running (potentially untrusted) applications.

More specifically, it is an SUID sandbox program that reduces the risk of security breaches by using Linux namespaces, seccomp-bpf and Linux capabilities. It allows a process and all its descendants to have their own private view of the globally shared kernel resources, such as the network stack, process table and mount table. Firejail can work in an SELinux or AppArmor environment, and it is integrated with Linux Control Groups.

Written in C with virtually no dependencies, the software runs on any Linux computer with a 3.x kernel version or newer. It can sandbox any type of processes: servers, graphical applications, and even user login sessions. The software includes sandbox profiles for a number of more common Linux programs, such as Mozilla Firefox, Chromium, VLC, Transmission etc.

The sandbox is lightweight, the overhead is low. There are no complicated configuration files to edit, no socket connections open, no daemons running in the background. All security features are implemented directly in Linux kernel and available on any Linux computer.

Videos

<table> <tr> <td> <a href="https://odysee.com/@netblue30:9/firefox:c" target="_blank"> <img src="https://thumbs.odycdn.com/acf4b1c66737feb97640fb1d28a7daa6.png" alt="Advanced Browser Security" width="240" height="142" border="10" /> <br/>Advanced Browser Security </a> </td> <td> <a href="https://odysee.com/@netblue30:9/nonet:7" target="_blank"> <img src="https://thumbs.odycdn.com/5be2964201c31689ee8f78cb9f35e89a.png" alt="How To Disable Network Access" width="240" height="142" border="10" /> <br/>How To Disable Network Access </a> </td> <td> <a href="https://odysee.com/@netblue30:9/divested:2" target="_blank"> <img src="https://thumbs.odycdn.com/f30ece33a6547af9ae48244f4ba73028.png" alt="Deep Dive" width="240" height="142" border="10" /> <br/>Deep Dive </a> </td> </tr> </table>

Security vulnerabilities

See SECURITY.md.

Installing

Debian

Debian stable (bullseye): We recommend to use the backports package.

Ubuntu

For Ubuntu 18.04+ and derivatives (such as Linux Mint), users are strongly advised to use the PPA.

How to add and install from the PPA:

sudo add-apt-repository ppa:deki/firejail
sudo apt-get update
sudo apt-get install firejail firejail-profiles

Reason: The firejail package for Ubuntu 20.04 has been left vulnerable to CVE-2021-26910 for months after a patch for it was posted on Launchpad:

What software is supported by the Ubuntu Security team?

Ubuntu is currently divided into four components: main, restricted, universe and multiverse. All binary packages in main and restricted are supported by the Ubuntu Security team for the life of an Ubuntu release, while binary packages in universe and multiverse are supported by the Ubuntu community.

Additionally, the PPA version is likely to be more recent and to contain more profile fixes.

See the following discussions for details:

Other

Firejail is available in multiple Linux distributions:

<details> <summary>Repology</summary> <p>

</p> </details>

Other than the aforementioned exceptions, as long as your distribution provides a supported version of firejail, it's generally a good idea to install it from the distribution.

The version can be checked with firejail --version after installing.

You can also install one of the released packages.

Building

You can clone the source code from this git repository and build manually:

git clone https://github.com/netblue30/firejail.git
cd firejail
./configure && make && sudo make install-strip

On Debian/Ubuntu you will need to install git and gcc.

To build with AppArmor support (which is usually used on Debian, Ubuntu, openSUSE and derivatives), install the AppArmor development libraries and pkg-config and use the --enable-apparmor ./configure option:

sudo apt-get install git build-essential libapparmor-dev pkg-config gawk

To build with SELinux support (which is usually used on Fedora, RHEL and derivatives), install libselinux1-dev (libselinux-devel on Fedora) and use the --enable-selinux ./configure option.

Detailed information on using firejail from git is available on the wiki.

Running the sandbox

To start the sandbox, prefix your command with firejail:

firejail firefox            # starting Mozilla Firefox
firejail transmission-gtk   # starting Transmission BitTorrent
firejail vlc                # starting VideoLAN Client
sudo firejail /etc/init.d/nginx start

Run firejail --list in a terminal to list all active sandboxes. Example:

$ firejail --list
1617:netblue:/usr/bin/firejail /usr/bin/firefox-esr
7719:netblue:/usr/bin/firejail /usr/bin/transmission-qt
7779:netblue:/usr/bin/firejail /usr/bin/galculator
7874:netblue:/usr/bin/firejail /usr/bin/vlc --started-from-file file:///home/netblue/firejail-whitelist.mp4
7916:netblue:firejail --list

Desktop integration

Integrate your sandbox into your desktop by running the following two commands:

firecfg --fix-sound
sudo firecfg

The first command solves some shared memory/PID namespace bugs in PulseAudio software prior to version 9. The second command integrates Firejail into your desktop. You would need to logout and login back to apply PulseAudio changes.

Start your programs the way you are used to: desktop manager menus, file manager, desktop launchers.

The integration applies to any program supported by default by Firejail. There are over 900 default applications in the current Firejail version, and the number goes up with every new release.

We keep the application list in src/firecfg/firecfg.config (/etc/firejail/firecfg.config when installed).

Security profiles

Most Firejail command line options can be passed to the sandbox using profile files.

You can find the profiles for all supported applications in etc/ (/etc/firejail/ when installed).

We also keep a list of profile fixes for previous released versions in etc-fixes/.

If you keep additional Firejail security profiles in a public repository, please give us a link:

Use this issue to request new profiles:

Profile requests

You can also use this tool to get a list of syscalls needed by a program:

contrib/syscalls.sh

Uninstalling

firecfg creates symlinks in /usr/local/bin, so to fully remove firejail, run the following before uninstalling:

sudo firecfg --clean

See man firecfg for details.

Note: Broken symlinks are ignored when searching for an executable in $PATH, so uninstalling without doing the above should not cause issues.

Latest released version: 0.9.72

Current development version: 0.9.73

--keep-shell-rc

       --keep-shell-rc
              By default, when using a private home directory, firejail copies
              files  from the system's user home template (/etc/skel) into it,
              which overrides attempts to whitelist the original  files  (such
              as  ~/.bashrc and ~/.zshrc).  This option disables this feature,
              and enables the user to whitelist the original files.

private-etc rework

       --private-etc, --private-etc=file,directory,@group
              The files installed by --private-etc are copies of the original
              system files from /etc directory.  By default, the command
              brings in a skeleton of files and directories used by most
              console tools:

              $ firejail --private-etc dig debian.org

              For X11/GTK/QT/Gnome/KDE  programs add @x11 group as a
              parameter. Example:

              $ firejail --private-etc=@x11,gcrypt,python* gimp

              gcrypt and /etc/python* directories are not part of the generic
              @x11 group.  File globbing is supported.

              For games, add @games group:

              $ firejail --private-etc=@games,@x11 warzone2100

              Sound and networking files are included automatically, unless
              --nosound or --net=none are specified.  Files for encrypted
              TLS/SSL protocol are in @tls-ca group.

              $ firejail --private-etc=@tls-ca,wgetrc wget https://debian.org

              Note: The easiest way to extract the list of /etc files accessed
              by your program is using strace utility:

              $ strace /usr/bin/transmission-qt 2>&1 | grep open | grep etc

We keep the list of groups in src/include/etc_groups.h.

Discussion:

private-etc rework

Landlock support

Added on #6078, which is based on #5315 from ChrysoliteAzalea/landlock
Compile-time detection based on linux/landlock.h - if the header is found, the feature is compiled in
Runtime detection based on whether Landlock is supported by the kernel and is enabled on the system

LANDLOCK
       Landlock is a Linux security module first introduced in version 5.13 of
       the  Linux  kernel.  It allows unprivileged processes to restrict their
       access to the filesystem.  Once imposed, these restrictions  can  never
       be  removed,  and  all child processes created by a Landlock-restricted
       processes inherit these restrictions.  Firejail supports Landlock as an
       additional  sandboxing  feature.  It can be used to ensure that a sand‐
       boxed application can only access files and directories that it was ex‐
       plicitly  allowed  to access.  Firejail supports populating the ruleset
       with both a basic set of rules (see --landlock) and with a  custom  set
       of rules.

       Important notes:

              - A process can install a Landlock ruleset only if it has either
              CAP_SYS_ADMIN in its effective capability set, or  the  "No  New
              Privileges"  restriction enabled.  Because of this, enabling the
              Landlock feature will also cause Firejail to enable the "No  New
              Privileges"  restriction,  regardless  of  the  profile  or  the
              --nonewprivs command line option.

              - Access to the /proc directory is managed through  the  --land‐
              lock.proc command line option.

              -  Access  to  the  /etc directory is automatically allowed.  To
              override this, use the --writable-etc command line option.   You
              can  also use the --private-etc option to restrict access to the
              /etc directory.

       To enable Landlock self-restriction on top of your current Firejail se‐
       curity  features,  pass  --landlock flag to Firejail command line.  You
       can also use --landlock.read, --landlock.write, --landlock.special  and
       --landlock.execute  options  together with --landlock or instead of it.
       Example:

       $ firejail --landlock --landlock.read=/media --landlock.proc=ro mc

Profile Statistics

A small tool to print profile statistics. Compile and install as usual. The tool is installed in the /usr/lib/firejail directory.

Run it over the profiles in /etc/profiles:

$ /usr/lib/firejail/profstats /etc/firejail/*.profile
No include .local found in /etc/firejail/noprofile.profile
Warning: multiple caps in /etc/firejail/tidal-hifi.profile
Warning: multiple caps in /etc/firejail/transmission-daemon.profile

Stats:
    profiles			1249
    include local profile	1248   (include profile-name.local)
    include globals		1217   (include globals.local)
    blacklist ~/.ssh		1117   (include disable-common.inc)
    seccomp			1127
    capabilities		1242
    noexec			1125   (include disable-exec.inc)
    noroot			1030
    memory-deny-write-execute	285
    restrict-namespaces		981
    apparmor			788
    private-bin			750
    private-dev			1090
    private-etc			763
    private-lib			78
    private-tmp			959
    whitelist home directory	609
    whitelist var		907   (include whitelist-var-common.inc)
    whitelist run/user		1214   (include whitelist-runuser-common.inc
					or blacklist ${RUNUSER})
    whitelist usr/share		690   (include whitelist-usr-share-common.inc
    net none			420
    dbus-user none 		705
    dbus-user filter 		164
    dbus-system none 		889
    dbus-system filter 		13