If username is set, then unbound will try to become that user using
`setusercontext`. But this is pointless since we are already instructing
systemd to launch unbound with that user.
So force username to be empty, which disables this behaviour in unbound.
This allows us to remove the capability granted, and also tighten the
syscall filter.
This changes the syscall filter to match that of upstream. Note that
SystemCallFilter=~foo bar
is completely different from
SystemCallFilter=~foo
SystemCallFilter=bar
The former one means that foo and bar are forbidden, and the latter
one means foo is forbidden and bar is granted!
conversions were done using https://github.com/pennae/nix-doc-munge
using (probably) rev f34e145 running
nix-doc-munge nixos/**/*.nix
nix-doc-munge --import nixos/**/*.nix
the tool ensures that only changes that could affect the generated
manual *but don't* are committed, other changes require manual review
and are discarded.
now nix-doc-munge will not introduce whitespace changes when it replaces
manpage references with the MD equivalent.
no change to the manpage, changes to the HTML manual are whitespace only.
the conversion procedure is simple:
- find all things that look like options, ie calls to either `mkOption`
or `lib.mkOption` that take an attrset. remember the attrset as the
option
- for all options, find a `description` attribute who's value is not a
call to `mdDoc` or `lib.mdDoc`
- textually convert the entire value of the attribute to MD with a few
simple regexes (the set from mdize-module.sh)
- if the change produced a change in the manual output, discard
- if the change kept the manual unchanged, add some text to the
description to make sure we've actually found an option. if the
manual changes this time, keep the converted description
this procedure converts 80% of nixos options to markdown. around 2000
options remain to be inspected, but most of those fail the "does not
change the manual output check": currently the MD conversion process
does not faithfully convert docbook tags like <code> and <package>, so
any option using such tags will not be converted at all.
Follow RFC 42 by having a settings option that is
then converted into an unbound configuration file
instead of having an extraConfig option.
Existing options have been renamed or kept if
possible.
An enableRemoteAccess has been added. It sets remote-control setting to
true in unbound.conf which in turn enables the new wrapping of
unbound-control to access the server locally. Also includes options
'remoteAccessInterfaces' and 'remoteAccessPort' for remote access.
Signed-off-by: Marc 'risson' Schmitt <marc.schmitt@risson.space>
Unbound throws the following error:
--8<---------------cut here---------------start------------->8---
error: failed to list interfaces: getifaddrs: Address family not supported by protocol
fatal error: could not open ports
--8<---------------cut here---------------end--------------->8---
The solution is pulled from upstream:
https://github.com/NLnetLabs/unbound/pull/351
Other units depend on nss-lookup.target and expect the DNS resolution to
work once that target is reached. The previous version
`wants=nss-lookup.target` made this unit require the nss-lookup.target
to be reached before this was started.
Another change that we can probalby do is drop the before relationship
with the nss-lookup.target. That might just be implied with the current
version.
This option allows users to specify a local UNIX control socket to
"remote control" the daemon. System users, that should be permitted to
access the daemon, must be in the `unbound` group in order to access the
socket. When a socket path is configured we are also creating the
required group.
Currently this only supports the UNIX socket mode while unbound actually
supports more advanced types. Users are still able to configure more
complex scenarios via the `extraConfig` attribute.
When this option is set to `null` (the default) it doesn't affect the
system configuration at all. The unbound defaults for control sockets
apply and no additional groups are created.
Previously we just applied a very minimal set of restrictions and
trusted unbound to properly drop root privs and capabilities.
With this change I am (for the most part) just using the upstream
example unit file for unbound. The main difference is that we start
unbound was `unbound` user with the required capabilities instead of
letting unbound do the chroot & uid/gid changes.
The upstream unit configuration this is based on is a lot stricter with
all kinds of permissions then our previous variant. It also came with
the default of having the `Type` set to `notify`, therefore we are also
using the `unbound-with-systemd` package here. Unbound will start up,
read the configuration files and start listening on the configured ports
before systemd will declare the unit "running". This will likely help
with startup order and the occasional race condition during system
activation where the DNS service is started but not yet ready to answer
queries.
Aditionally to the much stricter runtime environmet I removed the
`/dev/urandom` mount lines we previously had in the code (that would
randomly fail during `stop`-phase).
The `preStart` script is now only required if we enabled the trust
anchor updates (which are still enabled by default).
Another beneefit of the refactoring is that we can now issue reloads via
either `pkill -HUP unbound` or `systemctl reload unbound` to reload the
running configuration without taking the daemon offline. A prerequisite
of this was that unbound configuration is available on a well known path
on the file system. I went for /etc/unbound/unbound.conf as that is the
default in the CLI tooling which in turn enables us to use
`unbound-control` without passing a custom configuration location.
This is a refactor of how resolvconf is managed on NixOS. We split it
into a separate service which is enabled internally depending on whether
we want /etc/resolv.conf to be managed by it. Various services now take
advantage of those configuration options.
We also now use systemd instead of activation scripts to update
resolv.conf.
NetworkManager now uses the right option for rc-manager DNS
automatically, so the configuration option shouldn't be exposed.
Rather than special-casing the dns options in networkmanager.nix, use
the module system to let unbound and systemd-resolved contribute to
the newtorkmanager config.
While entering the chroot should provide the same amount of isolation,
the preStart script will run with full root privileges and so would
benefit from some isolation as well (in particular due to
unbound-anchor, which can perform network I/O).
1. The preStart script ensures consistent ownership, even if the unbound
user's uid has changed
2. The unbound daemon does not generate data that needs to be private to
it, so it would not matter that a different service would end up
owning its data (as long as unbound remains enabled, it should reclaim
ownership soon enough anyway).
Thus, there's no clear benefit to allocate a dedicated uid for the
unbound service. This releases uid/gid 48.
Also, because the preStart script creates the data directory, there's no
need to specify a homedir or ask for its creation.
/dev/random is an exhaustible resource. Presumably, unbound will not be
used to generate long-term encryption keys and so allowing it to use
/dev/random only increases the risk of entropy exhaustion for no
benefit.
Using pkgs.lib on the spine of module evaluation is problematic
because the pkgs argument depends on the result of module
evaluation. To prevent an infinite recursion, pkgs and some of the
modules are evaluated twice, which is inefficient. Using ‘with lib’
prevents this problem.
