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'.
