Difference between revisions of "AppArmor"

From ArchWiki
Jump to navigation Jump to search
m (→‎More Info: added Filename syntax highlighting)
(2.6.1-1 is out)
Line 7: Line 7:
AppArmor is currently available in the Arch Linux kernel, userspace support requires [[AUR]] packages.
AppArmor is currently available in the Arch Linux kernel, userspace support requires [[AUR]] packages.
* http://aur.archlinux.org/packages.php?ID=42279 (Out of Date, bump PKGVER to 2.6.1)
* http://aur.archlinux.org/packages.php?ID=42279
* https://bugs.archlinux.org/task/21406
* https://bugs.archlinux.org/task/21406

Revision as of 13:33, 18 August 2011

AppArmor is a MAC (Mandatory Access Control) system, implemented upon LSM (Linux Security Modules).

Implementation Status

AppArmor is currently available in the Arch Linux kernel, userspace support requires AUR packages.

It will take some time to make everything work Out-of-the-box. If you know how to build profiles yourself you shouldn't have too many problems.

aur/apparmor package

Added lot of features:

  • apparmor-parser
  • libapparmor
  • apparmor-utils
  • apparmor-profiles
  • apparmor-notify
  • apparmor-lib
  • apparmor-perl
  • apparmor-python
  • apparmor-ruby
  • apparmor-dbus
  • apparmor-profile-editor

But we still miss following features (TODO):

  • init (rc.d) scripts! http://aur.pastebin.com/beQ4BjGX
  • chase missing dependencies
  • test everything
  • make list of files that should go to backup=() arrays in packages...
  • changehat modules for PAM(!), Apache and Tomcat (btw those are dependent on libapparmor)
  • out-of-box-experience know-how
    • make some package with profiles for all [core] packages enabled by default without need for any further user configuration
    • etc...
  • apparmor gnome applet (can't build, deprecated...)

When compared to Ubuntu

we have almost everything that is in following Ubuntu packages:

  • apparmor
  • apparmor-profiles
  • apparmor-utils
  • apparmor-notify
  • apparmor-docs
  • libapparmor1
  • libapparmor-dev
  • libapparmor-perl

We don't have


AppArmor Packages

Kernel Configuration

Here is configuration of ArchLinux kernel which enables AppArmor (just FYI, you don't need to touch it):


However, integration of AppArmor into the 2.6.36 kernel is not quite complete. It is missing network mediation and some of the interfaces for introspection. See here for details. There are compatibility patches that can be applied to every recent kernel to reintroduce these interfaces. The patchset is pretty small and should be applied if you decide to use AppArmor. (Note: the patchset for 2.6.39 works with Kernel 3.0.x)

GRUB Configuration


To test profiles, or enforce the use of AppArmor it must be enabled at boot time. To do this add apparmor=1 security=apparmor to the kernel boot parameters in Template:Filename so the entry for the Arch Linux kernel looks something like

# (0) Arch Linux
title  Arch Linux [/boot/vmlinuz26]
root   (hd0,1)
kernel /boot/vmlinuz26 root=/dev/sdaX resume=/dev/sdaY ro apparmor=1 security=apparmor
initrd /boot/kernel26.img

Once you are happy with all your profiles, you may wish to force users to boot with AppArmor enabled. To do this add a password entry to the start of Template:Filename. This will prevent users editing any boot entries or using the Grub shell (which permits read access to any file on the system such as Template:Filename) before booting. You can also password protect any insecure entries in Template:Filename that you do not want unauthorized users to boot by adding the lock command (or another password) immediately below the title line for that entry. See Grub#Password_protection or Security in the Grub Manual for more details. If you are going through the trouble of securing Grub, don't forget to secure your BIOS settings as well or users will be able to boot from their own CD's and USB sticks, gaining root access to the machine.



Note that you can safely enable AppArmor and it will not affect the system at all until you enable it, load profiles, and set them to enforce mode with userspace tools. So you don't have to be afraid to enable AppArmor for testing purposes until you are enforcing AA profiles from init scripts (on each startup).

 # (0) Arch Linux
 menuentry "Arch Linux" {
   set root=(hd0,1)
   linux /vmlinuz26 root=/dev/sda1 ro apparmor=1 security=apparmor
   initrd /kernel26.img

After reboot you can test if apparmor is really enabled using this command as root:

 # cat /sys/module/apparmor/parameters/enabled 

(Y=enabled, N=disabled, no such file = module not in kernel)


AppArmor will be disabled by default in Arch Linux, so you will not need to disable it explicitly until you will build your own kernel with AppArmor enabled by default.

 # (0) Arch Linux
 menuentry "Arch Linux" {
   set root=(hd0,1)
   linux /vmlinuz26 root=/dev/sda1 ro apparmor=0 security=""
   initrd /kernel26.img

System Configuration

Mounts (Template:Filename securityfs)


 none     /sys/kernel/security securityfs defaults            0      0

Init scripts

In the future, we'll implement some Template:Filename scripts that will enable and load profiles during startup. http://aur.pastebin.com/beQ4BjGX The RC.d file of Slackware might be more interesting than Ubuntu's init.d version http://sprunge.us/IbeJ

For developers

From Template:Filename

 # NOTE: rc.apparmor initscripts that source this file need to implement
 # the following set of functions:
 # aa_action
 # aa_log_action_start
 # aa_log_action_end
 # aa_log_success_msg
 # aa_log_warning_msg
 # aa_log_failure_msg
 # aa_log_skipped_msg
 # aa_log_daemon_msg
 # aa_log_end_msg

UserSpace Tools


You can currently install userspace tools from AUR.


You need userspace tools that are compatible with your kernel version. The compatibility list can be found here: https://apparmor.wiki.kernel.org/index.php/AppArmor_versions eg.: Kernel 2.6.36 is compatible with AppArmor 2.5.1

More Info

AppArmor, like many other LSMs, supplements rather than replaces the default Discretionary access control.

Ubuntu, Suse and a number of other distributions use it by default. Red Hat (and Fedora) use SELinux which requires good userspace integration to work properly. People tend to agree that it's also much harder to configure correctly.

Taking a common example - A new Flash vulnerability: If you were to browse to a malicious website AppArmor can prevent the exploited plugin from accessing anything that may contain private information.

AppArmor profiles (usually) get stored in easy to read text files in Template:Filename

Every breach of policy triggers a message in the system log, and many distributions also integrate it into DBUS so that you get real-time violation warnings popping up on your desktop.

See also