This allows to set the default bit size for all the Diffie-Hellman
parameters defined in security.dhparams.params and it's particularly
useful so that we can set it to a very low value in tests (so it doesn't
take ages to generate).
Regardless for the use in testing, this also has an impact in production
systems if the owner wants to set all of them to a different size than
2048, they don't need to set it individually for every params that are
set.
I've added a subtest to the "dhparams" NixOS test to ensure this is
working properly.
Signed-off-by: aszlig <aszlig@nix.build>
This option allows us to turn off stateful generation of Diffie-Hellman
parameters, which in some way is still stateful as the generated DH
params file is non-deterministic.
However what we can avoid with this is to have an increased surface for
failures during system startup, because generation of the parameters is
done during build-time.
Another advantage of this is that we no longer need to take care of
cleaning up the files that are no longer used and in my humble opinion I
would have preferred that #11505 (which puts the dhparams in the Nix
store) would have been merged instead of #22634 (which we have now).
Luckily we can still change that and this change gives the user the
option to put the dhparams into the Nix store.
Beside of the more obvious advantages pointed out here, this also
effects test runtime if more services are starting to use this (for
example see #39507 and #39288), because generating DH params could take
a long time depending on the bit size which adds up to test runtime.
If we generate the DH params in a separate derivation, subsequent test
runs won't need to wait for DH params generation during bootup.
Of course, tests could still mock this by force-disabling the service
and adding a service or activation script that places pre-generated DH
params in /var/lib/dhparams but this would make tests less readable and
the workaround would have to be made for each test affected.
Note that the 'stateful' option is still true by default so that we are
backwards-compatible with existing systems.
Signed-off-by: aszlig <aszlig@nix.build>
Cc: @Ekleog, @abbradar, @fpletz
We're going to implement an option which allows us to turn off stateful
handling of Diffie-Hellman parameter files by putting them into the Nix
store.
However, modules now might need a way to reference these files, so we
add a now path option to every param specified, which carries a
read-only value of the path where to find the corresponding DH params
file.
I've also improved the description of security.dhparams.params a bit so
that it uses <warning/> and <note/>.
The NixOS VM test also reflects this change and checks whether the old
way to specify the bit size still works.
Signed-off-by: aszlig <aszlig@nix.build>
Cc: @Ekleog
We're going to make changes to the dhparams module so we really want to
make sure we don't break it, so having a NixOS VM test is to make sure
we don't blow things up and can iterate on it.
Signed-off-by: aszlig <aszlig@nix.build>
Cc: @Ekleog
Jacek Galowicz