From the kernel documentation:
> For reduced kernel memory fragmentation, slab caches can be
> merged when they share the same size and other characteristics.
> This carries a risk of kernel heap overflows being able to
> overwrite objects from merged caches (and more easily control
> cache layout), which makes such heap attacks easier to exploit
> by attackers. By keeping caches unmerged, these kinds of exploits
> can usually only damage objects in the same cache. [...]
Thus, it is more sane to leave slab merging disabled. KSPP and ClipOS
recommend this as well.
Signed-off-by: Peter Müller <peter.mueller@ipfire.org>
Acked-by: Michael Tremer <michael.tremer@ipfire.org>
Quoted from https://capsule8.com/blog/kernel-configuration-glossary/:
> Significance: Critical
>
> In support of Kernel Address Space Layout Randomization (KASLR) this randomizes
> the physical address at which the kernel image is decompressed and the virtual
> address where the kernel image is mapped as a security feature that deters
> exploit attempts relying on knowledge of the location of kernel code internals.
We tried to enable this back in 2020, and failed. Since then, things
may have been improved, so let's give this low-hanging fruit another
try.
Fixes: #12363
Signed-off-by: Peter Müller <peter.mueller@ipfire.org>
This patch, which has been merged into the mainline Linux kernel, but
not yet backported to the 5.15.x tree, precisely addresses our
situation: IPFire does not use systemd, but CONFIG_DEVTMPFS_MOUNT.
The only explanation I have for bug #12889 arising _now_ is that some
component (dracut, maybe) changed its behaviour regarding remounting of
already mounted special file systems. As current dracut won't (re)mount
any file system already found to be mounted, this means that the mount
options decided by the kernel remained untouched for /dev, hence being
weak in terms of options hardening possible.
As CONFIG_DEVTMPFS_SAFE would not show up in "make menuconfig", changes
to kernel configurations have been simulated.
Fixes: #12889
Cc: Michael Tremer <michael.tremer@ipfire.org>
Signed-off-by: Peter Müller <peter.mueller@ipfire.org>
This is solely needed for debugging of NFS issues. Due to the attack
surface it introduces, grsecurity recommends to disable it; as we do not
have a strict necessity for this feature, it is best to follow that
recommendation for security reasons.
Signed-off-by: Peter Müller <peter.mueller@ipfire.org>
Reviewed-by: Michael Tremer <michael.tremer@ipfire.org>
in kernel 5.15.32 the driver for ATH9K wlan cards is unstable.
This is one of the most used cards so we need this update before
releasing core167 final.
Signed-off-by: Arne Fitzenreiter <arne_f@ipfire.org>
LSM was found to render firmware flashing unusable, and patching out LSM
functionality for all features needed (such as /dev/io, direct memory
access and probably raw PCI access for older cards), this would
effectively render much of LSM's functionality useless as well.
For the time being, we do ship LSM, but do not enforce any protection
mode. Users hence can run it in "integrity" or even "confidentiality"
mode by custom commands; hopefully, we will be able to revert this
change at a future point.
Acked-by: Arne Fitzenreiter <arne.fitzenreiter@ipfire.org>
Signed-off-by: Peter Müller <peter.mueller@ipfire.org>
This is not necessary on our systems and according to the documentation
will reduce code size of the allocator which will result in better
performance.
Signed-off-by: Michael Tremer <michael.tremer@ipfire.org>
Acked-by: Peter Müller <peter.mueller@ipfire.org>
Signed-off-by: Arne Fitzenreiter <arne_f@ipfire.org>
This is a new type of metric to find out what resource is currently a
bottleneck for the whole system. We might use this for graphs.
Signed-off-by: Michael Tremer <michael.tremer@ipfire.org>
Acked-by: Peter Müller <peter.mueller@ipfire.org>
Signed-off-by: Arne Fitzenreiter <arne_f@ipfire.org>
