Firejail is a SUID sandbox program that reduces the risk of security breaches by restricting the running environment of untrusted applications 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, mount table. Firejail can work in a 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. 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
Project webpage: https://firejail.wordpress.com/
Download and Installation: https://firejail.wordpress.com/download-2/
Features: https://firejail.wordpress.com/features-3/
Documentation: https://firejail.wordpress.com/documentation-2/
FAQ: https://firejail.wordpress.com/support/frequently-asked-questions/
X11 support is built around Xpra (http://xpra.org/). So far I've seen it working on Debian 7 and 8, and Ubuntu 14.04. If you manage to run it on another distribution, please let me know. Example:
$ firejail --x11 --net=eth0 firefox
--x11 starts the server, --net is required in order to remove the main X11 server socket from the sandbox. More information here: https://firejail.wordpress.com/documentation-2/x11-guide/
FILE TRANSFER
These features allow the user to inspect the filesystem container of an
existing sandbox and transfer files from the container to the host
filesystem.
--get=name filename
Retrieve the container file and store it on the host in the cur‐
rent working directory. The container is specified by name
(--name option). Full path is needed for filename.
--get=pid filename
Retrieve the container file and store it on the host in the cur‐
rent working directory. The container is specified by process
ID. Full path is needed for filename.
--ls=name dir_or_filename
List container files. The container is specified by name
(--name option). Full path is needed for dir_or_filename.
--ls=pid dir_or_filename
List container files. The container is specified by process ID.
Full path is needed for dir_or_filename.
Examples:
$ firejail --name=mybrowser --private firefox
$ firejail --ls=mybrowser ~/Downloads
drwxr-xr-x netblue netblue 4096 .
drwxr-xr-x netblue netblue 4096 ..
-rw-r--r-- netblue netblue 7847 x11-x305.png
-rw-r--r-- netblue netblue 6800 x11-x642.png
-rw-r--r-- netblue netblue 34139 xpra-clipboard.png
$ firejail --get=mybrowser ~/Downloads/xpra-clipboard.png
Most Linux kernel security features require root privileges during configuration. The same is true for kernel networking features. Firejail (SUID binary) opens the access to these features to regular users. The privilege escalation is restricted to the sandbox being configured, and is not extended to the rest of the system. This arrangement works fine for user desktops or servers where the access is already limited.
If you not happy with a particular feature, all the support can be eliminated from SUID binary at compile time, or at run time by editing /etc/firejail/firejail.config file.
The following features can be enabled or disabled:
secomp Enable or disable seccomp support, default enabled.
chroot Enable or disable chroot support, default enabled.
bind Enable or disable bind support, default enabled.
network
Enable or disable networking features, default enabled.
restricted-network
Enable or disable restricted network support, default disabled.
If enabled, networking features should also be enabled (network
yes). Restricted networking grants access to --interface and
--net=ethXXX only to root user. Regular users are only allowed
--net=none.
userns Enable or disable user namespace support, default enabled.
x11 Enable or disable X11 sandboxing support, default enabled.
file-transfer
Enable or disable file transfer support, default enabled.
Currently 50 syscalls are blacklisted by default, out of a total of 318 calls (AMD64, Debian Jessie).
The current netfilter configuration (--netfilter option) looks like this:
*filter
:INPUT DROP [0:0]
:FORWARD DROP [0:0]
:OUTPUT ACCEPT [0:0]
-A INPUT -i lo -j ACCEPT
-A INPUT -m state --state RELATED,ESTABLISHED -j ACCEPT
# allow ping
-A INPUT -p icmp --icmp-type destination-unreachable -j ACCEPT
-A INPUT -p icmp --icmp-type time-exceeded -j ACCEPT
-A INPUT -p icmp --icmp-type echo-request -j ACCEPT
# drop STUN (WebRTC) requests
-A OUTPUT -p udp --dport 3478 -j DROP
-A OUTPUT -p udp --dport 3479 -j DROP
-A OUTPUT -p tcp --dport 3478 -j DROP
-A OUTPUT -p tcp --dport 3479 -j DROP
COMMIT
The filter is loaded by default for Firefox if a network namespace is configured:
$ firejail --net=eth0 firefox
--nice=value
Set nice value for all processes running inside the sandbox.
Example:
$ firejail --nice=-5 firefox
$ man firejail-profile
[...]
mkdir directory
Create a directory in user home. Use this command for
whitelisted directories you need to preserve when the sandbox is
closed. Subdirectories also need to be created using mkdir.
Example from firefox profile:
mkdir ~/.mozilla
whitelist ~/.mozilla
mkdir ~/.cache
mkdir ~/.cache/mozilla
mkdir ~/.cache/mozilla/firefox
whitelist ~/.cache/mozilla/firefox
[...]
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