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;
As discussed in https://github.com/NixOS/nixpkgs/pull/73763, prevailing
consensus is to revert that commit. People use the hardened profile on
machines and run nix builds, and there's no good reason to use
unsandboxed builds at all unless you're in a platform that doesn't
support them.
This reverts commit 00ac71ab19.
Running the manual on a TTY is useless in the graphical ISOs and not
particularly useful in non-graphical ISOs (since you can also run
'nixos-help').
Fixes#83157.
The system output usually contains a symlink from /etc to the static
configuration for the benefit of the stage-1 script in the initrd. The stage-2
script is usually started in the real root without such a symlink. In a
container, there is no stage-1 and the system output is used directly as a real
root. If the symlink is present, setup-etc.pl will create a symlink cycle and
the system cannot boot. There is no reason for the /etc link to exist in a
container because setup-etc.pl will create the necessary files. The container
module will now remove the /etc symlink and create an empty directory. The empty
/etc is for container managers to populate it with site-specific settings; for
example, to set the hostname. This is required to boot NixOS in an LXC container
on another host.
See also: #9735
Disables the build sandbox by default to avoid incompatibility with
defaulting user namespaces to false. Ideally there would be some kind of
linux kernel feature that allows us to trust nix-daemon builders to
allow both nix sandbox builds and disabling untrusted naemspaces at the
same time.
The rationale for this is that old filesystems have recieved little scrutiny
wrt. security relevant bugs.
Lifted from OpenSUSE[1].
[1]: 8cb42fb665
Co-Authored-By: Renaud <c0bw3b@users.noreply.github.com>
... otherwise enabling it causes a merge conflict.
Enabling it was necessary to give enough entropy for the sshd daemon in
my libvirt/nixops VM to generate keys see
https://github.com/NixOS/nixops/issues/1199.
systemd provides two sysctl snippets, 50-coredump.conf and
50-default.conf.
These enable:
- Loose reverse path filtering
- Source route filtering
- `fq_codel` as a packet scheduler (this helps to fight bufferbloat)
This also configures the kernel to pass coredumps to `systemd-coredump`.
These sysctl snippets can be found in `/etc/sysctl.d/50-*.conf`,
and overridden via `boot.kernel.sysctl`
(which will place the parameters in `/etc/sysctl.d/60-nixos.conf`.
Let's start using these, like other distros already do for quite some
time, and remove those duplicate `boot.kernel.sysctl` options we
previously did set.
In the case of rp_filter (which systemd would set to 2 (loose)), make
our overrides to "1" more explicit.
There's many reason why it is and is going to
continue to be difficult to do this:
1. All display-managers (excluding slim) default PAM rules
disallow root auto login.
2. We can't use wayland
3. We have to use system-wide pulseaudio
4. It could break applications in the session.
This happened to dolphin in plasma5
in the past.
This is a growing technical debt, let's just use
passwordless sudo.
slab_nomerge may reduce surface somewhat
slub_debug is used to enable additional sanity checks and "red zones" around
allocations to detect read/writes beyond the allocated area, as well as
poisoning to overwrite free'd data.
The cost is yet more memory fragmentation ...
For the hardened profile disable symmetric multi threading. There seems to be
no *proven* method of exploiting cache sharing between threads on the same CPU
core, so this may be considered quite paranoid, considering the perf cost.
SMT can be controlled at runtime, however. This is in keeping with OpenBSD
defaults.
TODO: since SMT is left to be controlled at runtime, changing the option
definition should take effect on system activation. Write to
/sys/devices/system/cpu/smt/control
For the hardened profile enable flushing whenever the hypervisor enters the
guest, but otherwise leave at kernel default (conditional flushing as of
writing).
Introduces the option security.protectKernelImage that is intended to control
various mitigations to protect the integrity of the running kernel
image (i.e., prevent replacing it without rebooting).
This makes sense as a dedicated module as it is otherwise somewhat difficult
to override for hardened profile users who want e.g., hibernation to work.
ZFS's popularity is growing, and not including it by default is a
bit frustrating. On top of that, the base iso includes ZFS
_anyway_ due to other packages depending upon it.
I think we're in the clear to do this on the basis that Oracle
probably doesn't care, it is probably fine (the SFLC agrees) and
we're a small fish. If a copyright holder asks us to, we can
definitely revert it again.
This reverts commit 33d07c7ea9.
The nixos-manual service already uses w3m-nographics for a variant that
drops unnecessary junk like various image libraries.
iso_minimal closure (i.e. uncompressed) goes from 1884M -> 1837M.
A module for security options that are too small to warrant their own module.
The impetus for adding this module is to make it more convenient to override
the behavior of the hardened profile wrt user namespaces.
Without a dedicated option for user namespaces, the user needs to
1) know which sysctl knob controls userns
2) know how large a value the sysctl knob needs to allow e.g.,
Nix sandbox builds to work
In the future, other mitigations currently enabled by the hardened profile may
be promoted to options in this module.
Introduced by 0f3b89bbed.
If services.nixosManual.showManual is enabled and
documentation.nixos.enable is not, there is no
config.system.build.manual available, so evaluation fails. For example
this is the case for the installer tests.
There is however an assertion which should catch exactly this, but it
isn't thrown because the usage of config.system.build.manual is
evaluated earlier than the assertions.
So I split the assertion off into a separate mkIf to make sure it is
shown appropriately and also fixed the installation-device profile to
enable documentation.nixos.
Signed-off-by: aszlig <aszlig@nix.build>
Cc: @oxij
Without this the graphical installer has no way to open the manual.
You can fix it yourself by installing any HTML browser but this might
be unfamiliar to users new to NixOS and without any other way to open
the manual. The downside is it will also increase download sizes.
Fixes#46537
Following up https://github.com/NixOS/nixpkgs/pull/23665
Bootable USB-drives are not limited to ISO-images, there can be "normal" MBR/GPT-partitioned disk connected via USB-rack.
Also, "uas" implies "usb-storage", so there is no need to mention both.
I broke it:
in job ‘nixos.iso_graphical.x86_64-linux’:
The option `services.udisks2.enable' has conflicting definitions, in `/nix/store/bwcjw1ddj94q83vbbnq1nnrs5aisaw59-source/nixos/modules/profiles/installation-device.nix' and `/nix/store/bwcjw1ddj94q83vbbnq1nnrs5aisaw59-source/nixos/modules/services/x11/desktop-managers/plasma5.nix'.
