The `nix.*` options, apart from options for setting up the
daemon itself, currently provide a lot of setting mappings
for the Nix daemon configuration. The scope of the mapping yields
convience, but the line where an option is considered essential
is blurry. For instance, the `extra-sandbox-paths` mapping is
provided without its primary consumer, and the corresponding
`sandbox-paths` option is also not mapped.
The current system increases the maintenance burden as maintainers have to
closely follow upstream changes. In this case, there are two state versions
of Nix which have to be maintained collectively, with different options
avaliable.
This commit aims to following the standard outlined in RFC 42[1] to
implement a structural setting pattern. The Nix configuration is encoded
at its core as key-value pairs which maps nicely to attribute sets, making
it feasible to express in the Nix language itself. Some existing options are
kept such as `buildMachines` and `registry` which present a simplified interface
to managing the respective settings. The interface is exposed as `nix.settings`.
Legacy configurations are mapped to their corresponding options under `nix.settings`
for backwards compatibility.
Various options settings in other nixos modules and relevant tests have been
updated to use structural setting for consistency.
The generation and validation of the configration file has been modified to
use `writeTextFile` instead of `runCommand` for clarity. Note that validation
is now mandatory as strict checking of options has been pushed down to the
derivation level due to freeformType consuming unmatched options. Furthermore,
validation can not occur when cross-compiling due to current limitations.
A new option `publicHostKey` was added to the `buildMachines`
submodule corresponding to the base64 encoded public host key settings
exposed in the builder syntax. The build machine generation was subsequently
rewritten to use `concatStringsSep` for better performance by grouping
concatenations.
[1] - https://github.com/NixOS/rfcs/blob/master/rfcs/0042-config-option.md
The wpa_supplicant service in the NixOS installer is unusable because
the control socket is disabled and /etc/wpa_supplicant.conf ignored.
The manual currently recommends manually starting the daemon and using
wpa_passphrase, but this requires figuring out the interface name,
driver and only works for WPA2 personal networks.
By enabling the control socket, instead, a user can configure the
network via wpa_cli (or wpa_gui in the graphical installer), which
support more advanced network configurations.
Since release 20.09 `rngd.enable` defaults to false, so this setting is redundant.
Also fix the `qemu-quest` section of the manual that incorrectly claimed
that `rngd` was enabled.
Encountered issues booting the live image on an Acer R11 Chromebook (CYAN). Got help from @samueldr on Freenode, and adding this module fixed it. Likely useful for other platforms/situations where booting from SD is necessary.
It's been 8.5 years since NixOS used mingetty, but the option was
never renamed (despite the file definining the module being renamed in
9f5051b76c ("Rename mingetty module to agetty")).
I've chosen to rename it to services.getty here, rather than
services.agetty, because getty is implemantation-neutral and also the
name of the unit that is generated.
Enabling the profile can lead to hard-to-debug issues, which should be
warned about in addition to the cost in features and performance.
See https://github.com/NixOS/nixpkgs/issues/108262 for an example.
Right now the UX for installing NixOS on a headless system is very bad.
To enable sshd without physical steps users have to have either physical
access or need to be very knowledge-able to figure out how to modify the
installation image by hand to put an `sshd.service` symlink in the
right directory in /nix/store. This is in particular a problem on ARM
SBCs (single board computer) but also other hardware where network is
the only meaningful way to access the hardware.
This commit enables sshd by default. This does not give anyone access to
the NixOS installer since by default. There is no user with a non-empty
password or key. It makes it easy however to add ssh keys to the
installation image (usb stick, sd-card on arm boards) by simply mounting
it and adding a keys to `/root/.ssh/authorized_keys`.
Importantly this should not require nix/nixos on the machine that
prepare the installation device and even feasiable on non-linux systems
by using ext4 third party drivers.
Potential new threats: Since this enables sshd by default a
potential bug in openssh could lead to remote code execution. Openssh
has a very good track-record over the last 20 years, which makes it
far more likely that Linux itself would have a remote code execution
vulnerability. It is trusted by millions of servers on many operating
systems to be exposed to the internet by default.
Co-authored-by: Samuel Dionne-Riel <samuel@dionne-riel.com>
linux-hardened sets kernel.unprivileged_userns_clone=0 by default; see
anthraxx/linux-hardened@104f44058f.
This allows the Nix sandbox to function while reducing the attack
surface posed by user namespaces, which allow unprivileged code to
exercise lots of root-only code paths and have lead to privilege
escalation vulnerabilities in the past.
We can safely leave user namespaces on for privileged users, as root
already has root privileges, but if you're not running builds on your
machine and really want to minimize the kernel attack surface then you
can set security.allowUserNamespaces to false.
Note that Chrome's sandbox requires either unprivileged CLONE_NEWUSER or
setuid, and Firefox's silently reduces the security level if it isn't
allowed (see about:support), so desktop users may want to set:
boot.kernel.sysctl."kernel.unprivileged_userns_clone" = true;
