On Fri, Dec 18, 2015 at 12:58 PM, H. Peter Anvin <h...@zytor.com> wrote: > On 12/18/2015 12:49 PM, Andy Lutomirski wrote: >> >> IOW, I like my idea in which signal delivery always sets PKRU to the >> application-requested-by-syscall values and sigreturn restores it. >> Kinda like sigaltstack, but applies to all signals and affects PKRU >> instead of RSP. >> > > I think this is the only sensible option, with the default being all zero. >
Or not quite all zero if we do Dave's experimental PROT_EXEC thing. Actually, I want to introduce a set of per-mm "incompatible" bits. By default, they'd be zero. We can, as needed, define bits that do something nice but break old code. I want one of the bits to turn vsyscalls off entirely. Another bit could say that the kernel is allowed to steal a protection key for PROT_EXEC. These bits would be read and written by prctl, but there could also be an ELF note mechanism to initialize them on execve without a syscall. --Andy -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/