[pkg-apparmor] Bug#1142783: broken $TMPDIR handling in postinst

[intrigeri]

Control: tag -1 + moreinfo

Hi,

Harald Dunkel (2026-07-25):
> Package: apparmor
> Version: 4.1.0-1
> If libpam-tmpdir is installed and if I try to install apparmor
> in a chroot, I get
>
> Setting up apparmor (4.1.0-1) ...
> mktemp: failed to create file via template '/tmp/user/0/tmp.XXXXXXXXXX': No such file or directory
> dpkg: error processing package apparmor (--configure):
>  installed apparmor package post-installation script subprocess returned error exit status 1

I'm not sure what I'm seeing here exactly but from where I stand it
looks like the value for your $TMPDIR (set by libpam-tmpdir) leaks
into an environment (chroot or whatever) where that $TMPDIR hasn't
been set up. In other words, you could trigger the exact same behavior
by setting $TMPDIR to any non-existent path, then trying to install
apparmor. I any package that uses mktemp in its postinst will expose
the same problem.

So to me it looks like a local configuration problem.
Or perhaps some build/chroot system blindly forwards $TMPDIR to
the chroot and that could be considered to be a bug.

But I don't really see what packages can do to guard against an
incorrectly configured $TMPDIR.

What am I missing?

Cheers,
-- 
intrigeri