So far the architecture for the tests was that we would use a systemd
socket unit using the Accept option to start a small shell process where
we can pipe commands into by connecting to the socket created by the
socket unit.
This is unnecessary since we can directly use the code snippets from the
individual subtests and systemd will take care of checking the return
code in case we get any assertions[^1].
Another advantage of this is that tests now run in parallel, so we can
do rather expensive things such as looking in /nix to see whether
anything is writable.
The new assert_permissions() function is the main driver behind this and
allows for a more fine-grained way to check whether we got the right
permissions whilst also ignoring irrelevant things such as read-only
empty directories.
Our previous approach also just did a read-only check, which might be
fine in full-apivfs mode where the attack surface already is large, but
in chroot-only mode we really want to make sure nothing is every
writable.
A downside of the new approach is that currently the unit names are
numbered via lib.imap1, which makes it annoying to track its definition.
[^1]: Speaking of assertions, I wrapped the code to be run with pytest's
assertion rewriting, so that we get more useful AssertionErrors.
Signed-off-by: aszlig <aszlig@nix.build>
When experimenting on ways how to refactor the test, I wrote a
significant enough amount of Python to warrant a dedicated Python file.
This commit is mainly to prepare for that and make it easier to track
renames.
Signed-off-by: aszlig <aszlig@nix.build>
The reason why I originally used the "description" attribute was that it
can be easily used to parametrise the tests so that we can specify
common constraints and apply it across a number of different
configurations.
When porting the tests to Python, the description attribute was replaced
by inlining it into the Python code, most probably because it was easier
to do in bulk since using Nix to generate the subtest parts would be
very complicated to do since we also had to please Black (a Python code
formatter that we no longer use in test scripts).
Since we now also want to support DynamicUser in systemd-confinement,
the need to parametrise the tests became apparent again because it's now
easier to refactor our subtests to run both with *and* without
DynamicUser set to true.
Signed-off-by: aszlig <aszlig@nix.build>
