It will affect both. The exact effect will depend on how things are set
up. Unconfined privileged processes will still have access to create
user namespaces as they see fit. The processes within the user namespace
will be subject to similar restrictions.

There is still room for refinement of the mediation being done. Whether
to virtualize the sysctl (not currently done), and what restrictions on
nested user namespace should be enforced (whether a stack unconfined or
system level unconfined is sufficient).

But generally speaking, what uid mappings are being done within a
container are not being taken into account by the mediation. If this is
something to be consider the current mediation can be extended to
support it. The mediation is based on current confinement and whether
the task has cap_sys_admin.

So currently it is possible to setup a container that is confined by a
system level profile but unconfined within the container, and that has
cap_sys_admin and have the container setup a further namespace.

If the system level confinement restricts the creation of user namespace
then regardless of the application is unconfined within the container or
confined and allowing access to user namespaces then access will be
restricted.

There currently is a lot of flexibility in what is supported. Feedback
over the next cycle or two as we refine the confinement and get things
packaged up will be appreciated.

-- 
You received this bug notification because you are a member of Kernel
Packages, which is subscribed to linux in Ubuntu.
https://bugs.launchpad.net/bugs/1990064

Title:
  unconfined profile denies userns_create for chromium based processes

Status in apparmor package in Ubuntu:
  Confirmed
Status in linux package in Ubuntu:
  Incomplete

Bug description:
  For Ubuntu 22.10, since the last kernel update, i canĀ“t launch any
  chromium based browser, due to apparmor denying userns_create

  dmesg shows:
  apparmor="DENIED" operation="userns_create" class="namespace" info="User 
namespace creation restricted" error=-13 profile="unconfined" pid=21323 
comm="steamwebhelper" requested="userns_create" denied="userns_create"

  This happens for every process which uses a chromium engine, like
  google chrome itself or in this case steamwebhelper.

  Might be related to this change?:
  
https://patchwork.kernel.org/project/netdevbpf/patch/20220801180146.1157914-5-f...@cloudflare.com/

  not sure if it got merged in this form though..

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