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>
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>
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 kernel configuration is a copy of our kernel configuration for
x86_64 on which I ran "make olddefconfig" which will set any unknown
values to their defaults.
This exists so that we have some kernel (which I did not try to boot) to
complete the build process.
Signed-off-by: Michael Tremer <michael.tremer@ipfire.org>
