Re: [RFC][PATCH] sysctl: Remove the sysctl system call

[Arnd Bergmann]

On Wed, Oct 2, 2019 at 12:54 AM Eric W. Biederman <ebiederm@xxxxxxxxxxxx> wrote:
> Kees Cook <keescook@xxxxxxxxxxxx> writes:
> > On Tue, Oct 01, 2019 at 01:36:32PM -0500, Eric W. Biederman wrote:
> >
> > I think you can actually take this further and remove (or at least
> > empty) the uapi/linux/sysctl.h file too.
>
> I copied everyone who had put this into a defconfig and I will wait a
> little more to see if anyone screams.  I think it is a safe guess that
> several of the affected configurations are dead (or at least
> unmaintained) as I received 17 bounces when copying everyone.

Looking at the arm defconfigs:

> arch/arm/configs/axm55xx_defconfig:CONFIG_SYSCTL_SYSCALL=y

No notable work on this platform since it got sold to Intel in 2014.
I think they still use it but not with mainline kernels that lack support
for most drivers and the later chips.

> arch/arm/configs/keystone_defconfig:CONFIG_SYSCTL_SYSCALL=y

Not that old either, but this hardware is mostly obsoleted by newer variants
that we support with the arm64 defconfig.

> arch/arm/configs/lpc32xx_defconfig:CONFIG_SYSCTL_SYSCALL=y
> arch/arm/configs/moxart_defconfig:CONFIG_SYSCTL_SYSCALL=y

Ancient hardware, but still in active use. These tend to have very little
RAM, but they both enable CONFIG_PROC_FS.

> arch/arm/configs/qcom_defconfig:CONFIG_SYSCTL_SYSCALL=y
> arch/arm/configs/zx_defconfig:CONFIG_SYSCTL_SYSCALL=y

These are for older Qualcomm and LG chips that tend to be used
with Android rather than the defconfig here. Maybe double-check
if the official android-common tree enables SYSCTL_SYSCALL.

      Arnd