In `scripts/Makefile.modinst`, the code that generates the list of
modules to install passes file names via the command line. When
installing a grsecurity kernel, this list appears to exceed the
shell's argument list limit, as in
make[2]: execvp: /nix/store/[...]-bash-4.3-p46/bin/bash: Argument list too long
The build does not fail, however, but the list of modules to be installed ends
up being empty. Thus, the resulting kernel package output contains no modules,
rendering it useless.
We work around this by patching the makefile to use `find -exec` to
process files. Why this would occur for grsecurity and not other
kernels is unknown, most likely there's something *else* that is
actually causing this behaviour, so this is a temporary fix until that
cause is found.
Fixes https://github.com/NixOS/nixpkgs/issues/20490
This reverts commit e02173c70c, reversing
changes made to c2b4a0d266.
Breaks all grsec packages; Not having binary substitutes for no good
reason is disruptive to my workflow, so I'll just revert this for now.
With the default kernel and thus with the build I have tested in
74ec94bfa2, we get an error during
modules_install:
make[2]: execvp: /nix/store/.../bin/bash: Argument list too long
I haven't noticed this build until I actually tried booting using this
kernel because make didn't fail here.
The reason this happens within Nix and probably didn't yet surface in
other distros is that programs only have a limited amount of memory
available for storing the environment and the arguments.
Environment variables however are quite common on Nix and thus we
stumble on problems like this way earlier - in this case Linux 4.8 - but
I have noticed this in 4.7-next as well already.
The fix is far from perfect and suffers performance overhead because we
now run grep for every *.mod file instead of passing all *.mod files
into one single invocation of grep.
But comparing the performance overhead (around 1s on my machine) with
the overall build time of the kernel I think the overhead really is
neglicible.
Signed-off-by: aszlig <aszlig@redmoonstudios.org>
Previously, features.grsecurity wasn't actually set due to a bug in the
grsec builder. We now rely on the generic kernel builder to set features
from kernelPatches.
Fixed for all available 4.x series kernels.
From CVE-2016-5829:
Multiple heap-based buffer overflows in the hiddev_ioctl_usage function
in drivers/hid/usbhid/hiddev.c in the Linux kernel through 4.6.3 allow
local users to cause a denial of service or possibly have unspecified
other impact via a crafted (1) HIDIOCGUSAGES or (2) HIDIOCSUSAGES ioctl
call.
This patch replaces the old grsecurity kernels with a single NixOS
specific grsecurity kernel. This kernel is intended as a general
purpose kernel, tuned for casual desktop use.
Providing only a single kernel may seem like a regression compared to
offering a multitude of flavors. It is impossible, however, to
effectively test and support that many options. This is amplified by
the reality that very few seem to actually use grsecurity on NixOS,
meaning that bugs go unnoticed for long periods of time, simply because
those code paths end up never being exercised. More generally, it is
hopeless to anticipate imagined needs. It is better to start from a
solid foundation and possibly add more flavours on demand.
While the generic kernel is intended to cover a wide range of use cases,
it cannot cover everything. For some, the configuration will be either
too restrictive or too lenient. In those cases, the recommended
solution is to build a custom kernel --- this is *strongly* recommended
for security sensitive deployments.
Building a custom grsec kernel should be as simple as
```nix
linux_grsec_nixos.override {
extraConfig = ''
GRKERNSEC y
PAX y
# and so on ...
'';
}
```
The generic kernel should be usable both as a KVM guest and host. When
running as a host, the kernel assumes hardware virtualisation support.
Virtualisation systems other than KVM are *unsupported*: users of
non-KVM systems are better served by compiling a custom kernel.
Unlike previous Grsecurity kernels, this configuration disables `/proc`
restrictions in favor of `security.hideProcessInformation`.
Known incompatibilities:
- ZFS: can't load spl and zfs kernel modules; claims incompatibility
with KERNEXEC method `or` and RAP; changing to `bts` does not fix the
problem, which implies we'd have to disable RAP as well for ZFS to
work
- `kexec()`: likely incompatible with KERNEXEC (unverified)
- Xen: likely incompatible with KERNEXEC and UDEREF (unverified)
- Virtualbox: likely incompatible with UDEREF (unverified)
