# Intro



Oz is a sandboxing system targeting everyday workstation applications.

It acts as a wrapper around application executables for completely transparent user operations. It achieves process containment through the use of [Linux Namespaces](http://man7.org/linux/man-pages/man7/namespaces.7.html), [Seccomp filters](http://man7.org/linux/man-pages/man2/seccomp.2.html), [Capabilities](http://man7.org/linux/man-pages/man7/capabilities.7.html), and X11 restriction using [Xpra](https://xpra.org/). It has built-in support with automatic configuration of bridge mode networking and also support working with contained network environment using the built in connection forwarding proxy.



[See the wiki for the complete technical documentation.](https://github.com/subgraph/oz/wiki/Oz-Technical-Details)



# Demo



<p align="center">

<a href="https://support.subgraph.com/videos/oz_evince_01.webm"><img src="https://raw.githubusercontent.com/subgraph/oz/docs/videos/oz_evince_01.gif" alt="OZ Sandbox Evince Demo"/></a>

</p>



# Warnings!



Please note that Oz is currently under major development and still at a very alpha stage. **As of this writting some features, like seccomp filters, are not yet available in the public master branch**. It is not intended for use in multi-users systems. Use it at your own risk!



# Installing



Due to the alpha nature of this project there currently is no package for easy installation.



## Prerequisites



Currently Oz only works and is only tested for Debian (>= jessie).

As of this writing it does **not** work in Ubuntu. While it has been minimally tested under Fedora,

there doesn't exist an RPM equivalent to `dpkg-divert` which allows to conveniantly wrap executables of existing program.

For seccomp filters you need at least kernel version 3.5.



It is highly recommend that you run it in conjunction with [grsecurity](https://grsecurity.net/).



### Dependencies



```

$ sudo apt-get install golang xpra bridge-utils libseccomp2 libcap2

```



You must also have the `veth` and `bridge` kernel module loaded to use *bridge network mode*.



### Grsec



If you are using grsecurity you will need to disable the following kernel options

permanently via the sysctl interface or by echoing values to files in

to files in `/proc/sys/kernel/grsecurity/`:



```

kernel.grsecurity.chroot_caps = 0

kernel.grsecurity.chroot_deny_chmod = 0

kernel.grsecurity.chroot_deny_mknod = 0

kernel.grsecurity.chroot_deny_mount = 0

```



See [Grsecurity/Appendix/Sysctl Options](https://en.wikibooks.org/wiki/Grsecurity/Appendix/Sysctl_Options)

for information on setting grsecurity sysctl options.



### Network Manager



If you are using Network-Manager you need to make sure to exclude the bridge interface.

To do so a file must be created in `/etc/NetworkManager/conf.d/oz.conf` containing:



```

[main]

plugins=keyfile



[keyfile]

unmanaged-devices=mac:6a:a8:2e:56:e8:9c;interface-name:oz0

```



If this file is missing `oz-daemon` will output a warning but it may fail to setup bridge networking.



### Bridge networking



Bridge networking is automatically configured by Oz, but you will need to setup

at minimum a few iptables masquerading rules and ebtables isolation rules as follows:



```

sudo iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE

sudo iptables -t nat -A POSTROUTING -o wlan0 -j MASQUERADE

sudo ebtables -P FORWARD DROP

sudo ebtables -F FORWARD

sudo ebtables -A FORWARD -i oz0 -j ACCEPT

sudo ebtables -A FORWARD -o oz0 -j ACCEPT

```



## Building



1. To setup a GOPATH for Oz, run the following commands (or you can use your

existing GOPATH):



```

$ export GOPATH=/opt/local/golang-oz

$ sudo mkdir -p $GOPATH

$ sudo chown user. $GOPATH

```



2. To build Oz with the required external Golang dependencies, run the following

commands:



```

$ go get github.com/tools/godep

$ go get -d github.com/subgraph/oz

$ cd $GOPATH/src/github.com/subgraph/oz/

$ $GOPATH/bin/godep go install ./...

$ sudo cp $GOPATH/bin/oz* /usr/local/bin

$ sudo mkdir -p /var/lib/oz/cells.d

$ sudo cp $GOPATH/src/github.com/subgraph/oz/profiles/*.json /var/lib/oz/cells.d/

```



## Enabling a profile



Once installed you can enable profiles using the `oz-setup` command as such (using the profile for the 'evince' application):



```

$ sudo oz-setup install evince

```



This will install a symlink to the oz client executable in place of the original, and rename the original with the `.unsafe` suffix.



## Disabling a profile



If you want to disable a profile that you're not using or prior to uninstalling Oz, you can run the following command (once again

with 'evince' as the target application):





```

$ sudo oz-setup remove evince

```



If you have already uninstalled Oz you can remove the divertions manually using the `dpkg-divert` command.



## Viewing the status of a profile



You can view the status of a profile using the `status` sub-command:



```

$ sudo oz-setup status /usr/bin/lowriter

Package divert is installed for:     /usr/bin/libreoffice

Package divert is installed for:     /usr/bin/lowriter

Package divert is installed for:     /usr/bin/lobase

Package divert is installed for:     /usr/bin/localc

Package divert is installed for:     /usr/bin/loffice

<...output truncated for clarity>

```



# Usage



Firstly you must launch the daemon utility either with the init script or manually:



```

$ sudo oz-daemon

```



Once the daemon is started you can transparently launch any applications for which you have enabled the profile.

This means Oz sandboxing will be used whether you launch your browser from gnome-shell or from the command line.



If you wish to run an executable outside of the sandbox simply call it with the `unsafe` suffix:



```

$ /usr/bin/evince.unsafe

```



# Advanced Usage Information



## Oz client commands



The `oz` executable acts as a client for the daemon when called directly. It provides a number of commands to interact with sandboxes.



* `profiles`: lists available profiles

* `launch <name>`: launches a sandbox for the given profile name, pass the `--noexec` flag to prevent execution of the default program

* `list`: lists the running sandboxes

* `kill <id>`: kills the sandbox with the given numerical id

* `kill all`: kills all running sandboxes

* `shell <id>`: enters a shell in a given sandbox, mostly useful for debugging

* `logs [-f]`: prints out the logs, pass `-f` to follow the output



## Oz-daemon configurations



In nearly every case the default configurations should be used, but for debugging and development purposes some flags are configurable inside of the `/etc/oz/oz.conf` file. You can view the current configuration by running the following command:



```

$ oz-setup config show



Config file     : /etc/oz/oz.conf

###########################################################

profile_dir     : /var/lib/oz/cells.d                     # Directory containing the sandbox profiles

shell_path      : /bin/bash                               # Path of the shell using when entering a sandbox

prefix_path     : /usr                                    # Prefix path containing the oz executables

sandbox_path    : /srv/oz                                 # Path of the sandboxes base

bridge_mac      : 6A:A8:2E:56:E8:9C                       # MAC Address of the bridge interface

divert_suffix   : unsafe                                  # Suffix using for dpkg-divert of application executables

nm_ignore_file  : /etc/NetworkManager/conf.d/oz.conf      # Path to the NetworkManager ignore config file, disables the warning if empty

use_full_dev    : false                                   # Give sandboxes full access to devices instead of a restricted set

allow_root_shell: false                                   # Allow entering a sandbox shell as root

log_xpra        : false                                   # Log output of Xpra

environment_vars: [USER USERNAME LOGNAME LANG LANGUAGE _] # Default environment variables passed to sandboxes

```



## Profiles



Profiles files are simple JSON files located, by default, in `/var/lib/oz/cells.d`. They must include at minimum the path to the executable to be sandboxed using the `path` key. It may also define more executables to run under the same sandbox under the `paths` array; in which case a `name` key must also be specified. Some other base options are also available:



* `allow_files`: whether to allow binding of files passed as arguments inside the sandbox



### Xserver



This section defines the configuration of the Xserver (namely [xpra](https://www.xpra.org/)).

Possible options are:



* `enabled`: whether or not to use the Xserver

* `enable_tray`: whether or not to enable the Xpra tray diagnostic menu/tray (This requires the `[Top Icons](https://extensions.gnome.org/extension/495/topicons/)` gnome-shell extension!)

* `tray_icon`: the path to an icon file to use for the to tray menu

* `window_icon`: the path to an icon file to use for windows

* `audio_mode`: one of [none|speaker|full] selects the audio passthrough mode (defaults: none)

* `disable_clipboard`: optionally disable clipboard sharing

* `EnableNotifications`: enable passing of dbus notifications



### Network configs



The network can be configured in one of three different ways: host, bridge, and empty namespace, as defined in the `type` key.



* `empty`: the sandbox will live with an empty network namespace (ie: only `lo` interface)

* `bridge`: the sandbox will have its own network namespace and use *veth* to join a bridge named `oz0`

* `host`: the sandbox will share the network namespace with the host (usually not desirable)





#### Port Forwarding config



Oz allows you to forward ports on the loopback interface between the host and the sandbox.

This is useful so that you can expose some services (such as a socks proxy) to the sandbox without giving the sandbox any real network access.

You may define as many forwards, called `sockets` in the configuration, as you like.

Each socket configuration contains the following keys:



* `type`: One of `client`, or `server`, this defines whether to connect (*client*) or listen (*server*) on the host side

* `proto`: One of `tcp`, or `udp`, or `socket`

* `port`: The network port number to connect to

* `destination`: *Optional*, in client mode this is the address to connect to, in server mode this is the address to bind to. Defaults to *localhost*.





### Bind list



There exists two types of *bindlists*: a whitelist and a blacklist.

The whitelist allows you to bring files from the host into the sandbox; while the blacklist allows you to remove access to specific files or directories.



Both of these types support a few ways of resolving files:



* In the path by using the `${PATH}` prefix.

* In the home by using the `${HOME}` prefix.

* By replacing `${UID}` with the user numeric id.

* By replacing `${USER}` with the user login.

* By path globbing using the `*` wildcard.





The whitelist carries some extra caveats:



* If the original file does not exist and is inside the home, an empty directory will be created in its place if "can_create" is set.

* If the original file is a symlink it is resolved, but the target remains the same.

* An item can be marked as read only with the `readonly` boolean key.

* Files that are passed as arguments to the command are automatically added to the whitelist.





### Environment



One can specify which environment variables to pass by defining them in this list.

It is also possible to define static variables by also defining a `value` attribute in the list item.



### Example



You can find a list of existing profiles in the repository. Here is the porfile for running the `torbrowser-launcher`:



```

{

"path": "/usr/bin/torbrowser-launcher"

, "xserver": {

	"enabled": true

	, "enable_tray": true

	, "tray_icon":"/usr/share/pixmaps/torbrowser80.xpm"

}

, "networking":{

	"type":"empty"

	, "sockets": [

		{"type":"client", "proto":"tcp", "port":9050}

		, {"type":"client", "proto":"tcp", "port":9051}

	]

}

, "whitelist": [

	{"path":"${HOME}/.local/share/torbrowser"}

	, {"path":"${HOME}/.cache/torbrowser"}

	, {"path":"${HOME}/.config/torbrowser"}

	, {"path":"${HOME}/Downloads/TorBrowser"}

	, {"path":"/run/tor/control.authcookie"}

]

, "blacklist": [

]

, "environment": [

	{"name":"TOR_SKIP_LAUNCH"}

	, {"name":"TOR_SOCKS_HOST"}

	, {"name":"TOR_SOCKS_PORT"}

	, {"name":"TOR_CONTROL_PORT"}

	, {"name":"TOR_CONTROL_AUTHENTICATE"}

]

}

```



<p align="center">

<img src="https://raw.githubusercontent.com/subgraph/oz/docs/images/oz_logo_02.png" alt="Obsidian Zebra" />

</p>