Comment 0 for bug 1298611

= linux =
This feature freeze exception is requested for signal and ptrace mediation via apparmor in the kernel. When used with a compatible apparmor userspace, signals and ptrace rules are supported. When used without a compatible apparmor userspace (eg, on a precise system with a trusty backport kernel), signal and ptrace mediation is not enforced (ie, you can use this kernel with an old userspace without any issues).

This feature has been tested on a 12.04 system, 14.04 system with current apparmor userspace, and 14.04 system with update apparmor userspace capable of supporting signal and ptrace mediation. This feature has been tested to work with on systems using lxc containers.

This feature is required to support comprehensive application confinement on Ubuntu Touch (a separate pull will be requested at a later date). This feature adds a significant security benefit to libvirt's qemu guest isolation which is fundamental to Ubuntu on Server/Cloud. This feature adds welcome improvement to administrators wishing to further protect their systems.

= apparmor userspace =
This feature freeze exception is requested for signal and ptrace mediation for apparmor userspace. When used with a compatible kernel, signals and ptrace rules are supported. When used without a compatible kernel (eg, immediately on Ubuntu Touch or with upstream kernels), signal and ptrace rules are skipped (ie, you can use this userspace with other kernels without issue).

This feature has been tested on a 14.04 system with current kernel and a 14.04 system with updated kernel capable of supporting signal and ptrace mediation. This feature has been tested to work with on systems using lxc containers.

This feature is required to support comprehensive application confinement on Ubuntu Touch. This feature adds a significant security benefit to libvirt's qemu guest isolation which is fundamental to Ubuntu on Server/Cloud. This feature adds welcome improvement to administrators wishing to further protect their systems.

While the apparmor userspace and kernel changes to support signal and ptrace mediation can happen at different times, the apparmor userspace upload must correspond with uploads for packages that ship AppArmor policy that require updates (eg, libvirt, lxc, etc). The packages outlined in https://wiki.ubuntu.com/SecurityTeam/KnowledgeBase/AppArmorProfiles will be tested to either work without modification to the policy or updated and tested to work with updated policy. Common rules will be added to the apparmor base abstraction such that most packages shipping apparmor policy will not require updating. These updates will be prepared, tested and published en masse via a silo ppa.