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Full system policy

Danger

Full system policy is still under early development:

  • Do not run it outside a development VM!
  • This is an advanced feature, you should understand what you are doing

You have been warned!!!

Quote

AppArmor is also capable of being used for full system policy where processes are by default not running under the unconfined profile. This might be useful for high security environments or embedded systems.

Source: AppArmor Wiki

Install

This feature is only enabled when the project is built with make full. Early policy load must also be enabled. Once apparmor.d has been installed in FSP mode, it is required to reboot to apply the changes.

In /etc/apparmor/parser.conf ensure you have:

write-cache
cache-loc /etc/apparmor/earlypolicy/
Optimize=compress-fast

Archlinux

In PKGBUILD, replace make by make full:

-  make
+  make full

Ubuntu & Debian

In debian/rules, add the following lines:

override_dh_auto_build:
    make full

OpenSUSE

In dists/apparmor.d.spec, replace %make_build by make full

-  %make_build
+  %make_build full

Partial install

Use the make full command to build instead of make

Structure

The profiles dedicated for full system policies are maintained in the _full group.

Systemd

In addition to systemd services (systemd-*) that have their own profiles, systemd itself, is confined using:

  • systemd: For systemd as PID 1, designed such as:

    • It allows internal systemd access,
    • It allows starting all common root services.
  • systemd-user: For systemd --user, designed such as:

    • It allows internal systemd user access,
    • It allows starting all common user services.

Both systemd and systemd-user should not fallback at all. I am working on some new profiles to ensure that 99% of program started by system have a profile.

These profiles are only intended to confine themselves. Any services started by systemd must have their corresponding profile. It means that for a given distribution, the following services must have profiles:

  • For systemd:

    /usr/lib/systemd/system-generators/*
    /usr/lib/systemd/system-environment-generators/*
    /usr/lib/systemd/system/*.service
    

  • For systemd-user

    /usr/lib/systemd/user-environment-generators/*
    /usr/lib/systemd/user-generators/*
    /usr/lib/systemd/user/*.service
    

To be allowed to run, additional root or user services may need to add extra rules inside the usr/systemd.d or usr/systemd-user.d directory. For example, when installing a new privileged service foo with stacking you may need to add the following to /etc/apparmor.d/usr/systemd.d/foo:

  @{lib}/foo rPx -> systemd//&foo,
  ...

Fallback

In addition to the systemd profiles, a full system policy needs to ensure that no program run in an unconfined state at any time. The fallbacks profiles consist of a set generic specialized profiles:

  • default is used for any classic user application with a GUI. It has full access to user home directories.
  • bwrap, bwrap-app are used for classic user application that are sandboxed with bwrap.

Warning

The main fallback profile (default) is not intended to be used by priviligied program or service. Such programs must have they dedicaded profile and would break otherwise.

Additionally, special user access can be setup using PAM rules set such as a random shell interactively opened (as user or as root).