Re: General flags to turn things off (getrandom, pid lookup, etc)
From: Dave Jones
Date: Fri Jul 25 2014 - 16:15:59 EST
On Fri, Jul 25, 2014 at 11:30:48AM -0700, Andy Lutomirski wrote:
> There is recent interest in having a way to turn generally-available
> kernel features off. Maybe we should add a good one so we can stop
> bikeshedding and avoid proliferating dumb interfaces.
> Things that might want to be turn-off-able include:
> - getrandom with GRND_RANDOM [from the getrandom threads]
> - Any lookup of a non-self pid [from the capsicum thread]
> - Any lookup of a pid outside the caller thread group [capsicum]
> - Various architectural things (personal wishlist), e.g.:
> - RDTSC and userspace HPET access
> - CPUID?
> - 32-bit GDT code segments [huge attack surface]
> - 64-bit GDT code segments [probably pointless]
I'm not sure there's value in disabling cpuid dev interface,
when the instruction is unprivileged.
> I would propose a new syscall for this:
> long restrict_userspace(int mode, int type, int value, int flags);
do the restrictions happen system-wide like in say SELinux,
or only within the calling process, like seccomp ?
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/