Support

 

Please report the problems you run into on our GitHub bug tracker. For general questions you can also use the comment section on any page on this website. Security bugs are taken seriously, please email them to netblue30@yahoo.com

 

Profile fixes

Fixed security profile fixes are available for various Firejail versions in this GitHub directory. The fixes cover applications such as Firefox browser (version 60 is breaking badly!), LibreOffice (crashes on Ubuntu 18.04), gedit. Manually overwrite the files in /etc/firejail directory with the files from GitHub.

Firefox example:

  1. in your browser, open the GitHub page corresponding to your Firejail version (0.9.38, 0.9.52)
  2. in a text editor, open the file with the same name in /etc/firejail directory (“sudo /usr/bin/gedit /etc/firejail/firefox.profile“)
  3. cut&paste from the web page into the text editor
 

Frequently Asked Questions

 
 

Technology

Why on earth should I use Firejail?

Some existing Linux security solutions are easily defeated from internal and/or external threats. Other solutions are just too difficult to put in place. Firejail’s approach is radically different.

For us, the user always comes first. We manage to keep the learning curve down. Actually, most of the time you don’t need to learn anything, just prefix your application with “firejail” and run it. This makes Firejail ideal for the regular, not-so-skilled home user.

We use the latest Linux kernel security features, such as namespaces and seccomp-bpf. In our view these features are mature, and have been extensively tested in the market place by products such as Google Chrome or Docker.

 

How does it compare with Docker, LXC, nspawn?

Docker, LXC and nspawn are container managers. A container is a separate root filesystem. The software runs in this new filesystem. Firejail is a security sandbox. It works on your existing filesystem. It is modeled after the security sandbox distributed with Google Chrome.

Containers and sandboxes use the same Linux kernel technology, Linux namespaces. The developer focus is different. Containers target the virtualization market, while sandboxes focus on application security.

 

What is the overhead of the sandbox?

The sandbox itself is a very small process. The setup is fast, typically several milliseconds. After the application is started, the sandbox process goes to sleep and doesn’t consume any resources. All the security features are implemented inside the kernel, and run at kernel speed.

 

Applications

 

Firefox doesn’t open in a new sandbox. Instead, it opens a new tab in an existing Firefox instance

By default, Firefox browser uses a single process to handle multiple windows. When you start the browser, if another Firefox process is already running, the existing process opens a new tab or a new window. Make sure Firefox is not already running when you start it in Firejail sandbox.

 

How do I run two instances of Firefox?

Start the first Firefox instance as usual:

$ firejail firefox

Then, start the second sandbox:

$ firejail --private firefox -no-remote
 

How do I run VLC in a sandbox without network access?

–net=none command line switch installs a new TCP/IP stack in your sandbox. The stack is not connected to any external interface. For the programs running inside, the sandbox looks like a computer without any Ethernet interface.

$ firejail --net=none vlc

The best way to handle the command line switch is to place it in a custom profile in ~/.config/firejail file in your home directory. Create a vlc.profile text file in this directory, with the following content:

$ cat ~/.config/firejail/vlc.profile
include /etc/firejail/vlc.profile
net none

 

Can you sandbox Steam games and Skype?

Support for Steam, Wine and Skype has been around since version 0.9.34. Quite a number of other closed-source programs are supported.

Running ls /etc/firejail/*.profile will list all the security profiles distributed with Firejail. Programs not listed there, are handled by a very restrictive /etc/firejail/default.profile.

 

Known Problems

 

PulseAudio 7.0/8.0 issue

The srbchannel IPC mechanism, introduced in PulseAudio 6.0, was enabled by default in release 7.0. Many Linux users are reporting sound problems when running applications in Firejail sandbox. It affects among others Arch, Ubuntu 16.04 and Mint users. This problem was fixed PulseAudio version 9.0. Run “firecfg –fix” in a terminal or apply the following configuration to mask the problem:

$ mkdir -p ~/.config/pulse
$ cd ~/.config/pulse
$ cp /etc/pulse/client.conf .
$ echo "enable-shm = no" >> client.conf

A logout/login is required for the changes to take effect.

If you have problems with PulseAudio 9.x use the previous fix, or configure “enable-memfd = yes” in /etc/pulse/daemon.conf.

 

Firefox 60 problems

Firefox 60 doesn’t work with Firejail version 0.9.52 or older. Patched security profiles for are available for Firejail versions 0.9.38.x (LST) and 0.9.52. You can find them in our profile fixes section. Another option is to install Firejail 0.9.54.

 

LibreOffice on Ubuntu 18.04

LibreOffice crashes when sandboxed with Firejail version 0.9.52 in Ubuntu 18.04. A patched security profile for Firejail 0.9.52 is available in our profile fixes section. Another option is to install Firejail 0.9.54.

 

Cannot install new software while Firejail is running

File blacklisted in a running jail cannot be removed from outside of jail. This causes serious inconvenience when using Firejail with long time running processes. For example, preventing user from updating system normally, as files like /bin/su, /bin/mount, /usr/bin/sudo are blacklisted by default. Also, admin commands for adding users and groups will fail.

Firejail implements blacklisting by mounting an empty, read-only file or directory on top of the original file. The kernel, at least the older kernels, will refuse to delete the file because it is a mount point in some other place in the system.

The problem is fixed in Linux kernels 3.18 or newer. This is the commit: vfs: Lazily remove mounts on unlinked files and directories

 

Cannot connect to ibus-daemon in a new network namespace

ibus-daemon is used to change the system language, for example to switch between English (US) input and Japanese inputs. In a sandbox using a new network namespace ibus-daemon socket is disabled and keyboard switching capability is lost.

 

Firefox crashing on Netflix, AMDGPU PRO, Nvidia closed source drivers

We are still working on these problems. From what we’ve seen so far, these programs make liberal use of system calls such as chroot and ptrace. These syscalls have no place in regular, well behaved programs, and seccomp kills the application immediately. Workarounds involve disabling seccomp and allowing ptrace utility. Example:

$ firejail --allow-debuggers --ignore=seccomp --ignore=protocol firefox -no-remote
 

I’ve noticed the title bar in Firefox shows “(as superuser)”, is this normal?

The sandbox process itself runs as root. The application inside the sandbox runs as a regular user. “ps aux | grep firefox” reports Firefox process running as a regular user.

The same problem was seen on other programs as well (VLC, Audacious, Transmission), and it is believed to be a bug in the window manager. You can find a very long discussion on the development site: https://github.com/netblue30/firejail/issues/258

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212 thoughts on “Support

  1. Nonnya

    Ever since I ran sudo firecfg, my browsers won’t launch. I have to uninstall firejail completely to get them to work. Any workaround for this?

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  2. JoeJoe

    Ever since I ran sudo firecfg, my browsers won’t launch. I have to uninstall firejail completely to get them to work. Any workaround for this?

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  3. Simon

    Why is it the case that if I run a new terminal window from firejail, none of the sandbox features seem to work? Specifically, if I run firejail –noroot id, I see that I’m a member of groups 1000 and 65534 (nogroup). But if I run firejail –noroot xfce4-terminal, and in that new terminal run id, I see that I’m a member of groups 1000, 4, 27 and so on, i.e. it seems as if the new terminal window isn’t constrained by the sandbox. I see the same thing in brwap (bubblewrap), so I assume it’s something I’m not understanding about how the sandboxes work, so would appreciate any clarification of what’s actually going on here. And firejail is great, by the way, the documentation is very good compared to bwrap.

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  4. lin

    i read you removed all –private & –overlay options from firejail with > v0.9.56 (okt’18) 😦 really? have i misunderstood something? how do i get back the important security features i used to use?

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  5. Deniz

    Are colons and parentheses in directory names supported? If so, how would one use those characters? I know spaces are not to be escaped, but whether I escape colons and parentheses or not, I can’t seem to stop getting the error “Error: blabla is an invalid filename” (without the quotes). I’m using firejail 0.9.56-2 in Debian testing/buster.

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  6. jo

    CANT GET FIREJAIL TO WORK WITH FIREFOX 64.0 OR CHROME 71.0.3578.98 (Official Build) (64-bit). ON LINUX MINT 18.3 SYLVIA OR KODACHI 5.6. ON HP I3 16GB 240GBSSD .WHAT A WASTE OF TIME!!!

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