Ok, I spent quite a bit of time evaluating this and believe this bug can
be closed, but other bugs open.

In looking at this I created https://code.launchpad.net/~jdstrand/+git
/test-overlay (to build simply git clone, run 'snapcraft', install the
snap and then run 'test-overlay' for instructions on how to test
different things).

For this bug, the test code was broken and it didn't pivot_root. I'm not
sure if it did pivot_root back when this was filed (I didn't check). The
use of attach_disconnected is required because upperdir (man 8 mount,
look for overlay) is disconnected. Once attach_disconnected is present,
all file paths are mediatable:

- when using just an overlay, the paths show up where you expect them to be in 
the filesystem
- when using overlay plus chroot paths are mediatable but an alias rule is 
really needed to have worthwhile policy (otherwise you need to keep the 
inner-chroot policy and outer-system policy in sync). Also logged denials have 
the overlay mountpoint prefixed. This is consistent with how apparmor works 
with chroots
- when using overlay plus private mount namespace plus pivot_root, no alias 
rule is required and logged path denials look like the system paths (ie, the 
overlay mountpoint is not prefixed)

In all, closing this bug as Invalid. I'll be filing new bugs for various
issues I found in my investigation.

** Changed in: linux (Ubuntu)
       Status: Triaged => Won't Fix

** Changed in: apparmor (Ubuntu)
       Status: Confirmed => Won't Fix

** Changed in: apparmor
       Status: In Progress => Invalid

** Changed in: apparmor (Ubuntu)
       Status: Won't Fix => Invalid

** Changed in: linux (Ubuntu)
       Status: Won't Fix => Invalid

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https://bugs.launchpad.net/bugs/1408106

Title:
  attach_disconnected not sufficient for overlayfs

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