apparmor.d/README.md

[<img src="https://gitlab.com/uploads/-/system/project/avatar/25600351/logo.png" align="right" height="110"/>][project]

# apparmor.d

[![][workflow]][action] [![][build]][project]  [![][quality]][goreportcard]

**Full set of AppArmor profiles**

> **Warning**: This project is still in early development. Help is very welcome
> see [`CONTRIBUTING.md`](CONTRIBUTING.md) 

## Description 

A set of over 1400 AppArmor profiles which aims is to confine most of Linux base
applications and processes.

**Goals & Purpose**
- Support all distributions that support AppArmor:
  * *Currently*: Archlinux, Debian 11 and the last Ubuntu LTS.
  * Not (yet) tested on openSUSE
- Target both desktop and server,
- Confine all root processes. Eg: all systemd tools, bluetooth, dbus, polkit,
  NetworkManager, OpenVPN, GDM, rtkit, colord...
- Confine all Desktop environments:
  * *Currently only Gnome*, see `apparmor.d/groups/gnome`
- Confine all user services: Eg: Pipewire, Gvfsd, dbus, xdg, xwayland...
- Confine some "special" user applications: web browser, file browser...
- Should not break a normal usage of the confined software.
- Fully tested (Work in progress),

> This project is based on the excellent work from [Morfikov][upstream] and aims
to extend it to more Linux distributions and desktop environements.


## Concepts

There are over 50000 Linux packages and even more applications. It is simply not possible to write an AppArmor profile for all of them. Therefore a question arises: *What to confine and why?*

We take inspiration from the [Android/ChromeOS Security Model][android_model] and we apply it to the Linux world. Modern [linux security implementation][clipos] usually consider a core base image with a carefully set of selected applications. Everything else should be sandboxed. Therefore, this project tries to confine all the *core* applications you will usually find in a Linux system: all systemd services, xwayland, network, bluetooth, your desktop environment... Non-core user applications are out of scope as they should be sandboxed using a dedicated tool (minijail, bubblewrap...).

This is fundamentally different from how AppArmor is used on Linux server as it is common to only confine the applications that face the internet and/or the users.



## Installation

> **Warning**: In order to not break your system, the default package configuration install all profiles in complain mode. They can be enforced later. See [Enforce Mode](#enfore-mode)

**Requirements**
* An `apparmor` based linux distribution.
* Base profiles and abstractions shipped with AppArmor are supposed to be
  installed.
* Go (build dependency only)
* rsync (build dependency only)

**Archlinux**

`apparmor.d-git` is available in the [Arch User Repository][aur]:
```sh
git clone https://aur.archlinux.org/apparmor.d-git.git
cd apparmor.d-git
makepkg -s
sudo pacman -U apparmor.d-*.pkg.tar.zst \
  --overwrite etc/apparmor.d/tunables/global \
  --overwrite etc/apparmor.d/tunables/xdg-user-dirs \
  --overwrite etc/apparmor.d/abstractions/trash
```

> **Note**: The overwrite options are only required on the first install. You can use `yay` or your preferred AUR install method to update it.

The `PKGBUILD` included in this repository is intended for development only.

**Debian / Ubuntu**

Build using standard Debian package build tools:
```sh
sudo apt install apparmor-profiles build-essential config-package-dev debhelper golang-go rsync git
git clone https://github.com/roddhjav/apparmor.d.git
cd apparmor.d
dpkg-buildpackage -b -d --no-sign
sudo dpkg -i ../apparmor.d_*_all.deb
```

**Partial install**

> **Note**: Manual installation is discouraged because files undergo post-processing dependent on the OS and desired configuration

For test purpose, you can install a specific profile with the following commands. The tool will also install required abstractions and tunables:
```
sudo ./pick <profiles-name>
```
However, `pick` does not fully automate single profile installation yet (the PR is welcome [#77](https://github.com/roddhjav/apparmor.d/issues/77)). For convenient usage you should:
- Ensure all related abstractions are installed (automated)
- Ensure all related tunables are installed (automated)
- Remove `abi` statement if needed (automated)
- Set distribution-related flags from `dists/flags` (not automated)
- Either switch desired `rPx` rules to `rPUx` (fallback to unconfined) or install these related profiles (not automated)


## Usage

**Enabled profiles**

Once installed and with the rules enabled, you can ensure the rules are loaded
with `sudo aa-satus`, it should give something like:
```
apparmor module is loaded.
1137 profiles are loaded.
794 profiles are in enforce mode.
   ...
343 profiles are in complain mode.
   ...
0 profiles are in kill mode.
0 profiles are in unconfined mode.
130 processes have profiles defined.
108 processes are in enforce mode.
   ...
22 processes are in complain mode.
   ...
0 processes are unconfined but have a profile defined.
0 processes are in mixed mode.
0 processes are in kill mode.
```

You can also list the current processes alongside with their security profile with
`ps auxZ`. Most of the process should then be confined.

**AppArmor Log**

The provided command `aa-log` allow you review AppArmor generated messages in a
colorful way:

```
$ aa-log
   ...
```

`aa-log` can optionally be given a profile name as argument to
only show the log for a given profile:
```
$ aa-log dnsmasq
DENIED  dnsmasq open /proc/sys/kernel/osrelease comm=dnsmasq requested_mask=r denied_mask=r
DENIED  dnsmasq open /proc/1/environ comm=dnsmasq requested_mask=r denied_mask=r
DENIED  dnsmasq open /proc/cmdline comm=dnsmasq requested_mask=r denied_mask=r
```


## Personalisation

**AppArmor configuration**

As they are a lot of rules, it is recommended to enable caching AppArmor profiles.
In `/etc/apparmor/parser.conf`, uncomment `write-cache` and `Optimize=compress-fast`.
See [Speed up AppArmor Start] on the Arch Wiki for more information.


**Personal directories**

The profiles heavily use the XDG directory variables defined in `/etc/apparmor.d/tunables/xdg-user-dirs`. You can personalise these values with by creating a
file such as `/etc/apparmor.d/tunables/xdg-user-dirs.d/perso` with (for example)
the following content:
```sh
@{XDG_VIDEOS_DIR}+="Films"
@{XDG_MUSIC_DIR}+="Musique"
@{XDG_PICTURES_DIR}+="Images"
@{XDG_BOOKS_DIR}+="BD" "Comics"
@{XDG_PROJECTS_DIR}+="Git" "Papers"
```

**Local profiles**

You can extend a profile with your own rules by creating a file in the 
`/etc/apparmor.d/local/` directory. For example, to extend the `gnome-shell`
profile, create a file `/etc/apparmor.d/local/gnome-shell` and add your rules.
Then, reload the apparmor rules with `sudo systemctl restart apparmor`.


## Enfore Mode

The default package configuration installs all profile in *complain* mode.
Once you tested them and it works fine, you can easily switch to *enforce* mode.
To do this, edit `PKGBUILD` on Archlinux or `debian/rules` on Debian and remove 
the `--complain` option to the configure script. Then build the package as usual:
```diff
-  ./configure --complain
+  ./configure
```

Do not worry, the profiles that are not considered stable are kept in complain mode.
They can be tracked in the `dists/flags` directory.


## Troubleshooting

**AppArmor messages**

Ensure that `auditd` is installed and running on your system in order to read
AppArmor log from `/var/log/audit/audit.log`. Then you can see the log with `aa-log`


**System Recovery**

Issue in some core profiles like the systemd suite, or the desktop environment
can fully break your system. This should not happen a lot, but if it does here
is the process to recover your system on Archlinux:
1. Boot from a Archlinux live USB
1. If you root partition is encryped, decrypt it: `cryptsetup open /dev/<your-disk-id> vg0`
1. Mount your root partition: `mount /dev/<your-plain-disk-id> /mnt`
1. Chroot into your system: `arch-chroot /mnt`
1. Check the AppArmor messages to see what profile is faulty: `aa-log`
1. Temporarily fix the issue with either:
   - When only one profile is faultly, remove it: `rm /etc/apparmor.d/<profile-name>`
   - Otherwise, you can also remove the package: `pacman -R apparmor.d`
   - Alternativelly, you may temporarily disable apparmor as it will allow you to
     boot and studdy the log: `systemctl disable apparmor`
1. Exit, umount, and reboot:
   ```sh
   exit
   umount -R /mnt
   reboot
   ```
1. Create an issue and report the output of `aa-log`


## Tests

A full test suite to ensure compatibility across distributions and softwares is still a work in progress.

Here is an overview of the current CI jobs:

**On Gitlab CI**
- Package build for all supported distribution
- Profiles preprocessing verification for all supported distribution
- Go based command linting and unit tests

**On Github Action**
- Integration test on the ubuntu-latest VM: run a simple list of tasks with
  all the rules enabled and ensure no new issue has been raised. Github Action
  is used as it offers a direct access to a VM with AppArmor included.


## Contribution

Feedbacks, contributors, pull requests are all very welcome. Please read the
[`CONTRIBUTING.md`](CONTRIBUTING.md) file for more details on the contribution process.


## License

This program is based on Mikhail Morfikov's [apparmor profiles project][upstream] and thus has the same license (GPL2).

```
Copyright (C)  Alexandre PUJOL & Mikhail Morfikov

This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; version 2 of the License.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License along
with this program; if not, write to the Free Software Foundation, Inc.,
51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
```

[upstream]: https://gitlab.com/morfikov/apparmemall
[project]: https://gitlab.com/roddhjav/apparmor.d
[build]: https://gitlab.com/roddhjav/apparmor.d/badges/master/pipeline.svg?style=flat-square
[workflow]: https://img.shields.io/endpoint.svg?url=https%3A%2F%2Factions-badge.atrox.dev%2Froddhjav%2Fapparmor.d%2Fbadge&style=flat-square
[action]: https://actions-badge.atrox.dev/roddhjav/apparmor.d/goto
[quality]: https://img.shields.io/badge/go%20report-A+-brightgreen.svg?style=flat-square
[goreportcard]: https://goreportcard.com/report/github.com/roddhjav/apparmor.d

[aur]: https://aur.archlinux.org/packages/apparmor.d-git
[android_model]: https://arxiv.org/pdf/1904.05572
[clipos]: https://clip-os.org/en/
[Speed up AppArmor Start]: https://wiki.archlinux.org/title/AppArmor#Speed-up_AppArmor_start_by_caching_profiles
[write xor execute]: https://en.wikipedia.org/wiki/W%5EX