Date: Fri, 14 Jan 2022 14:36:24 +0100 From: Florian Weimer <fweimer@...hat.com> To: Andy Lutomirski <luto@...nel.org> Cc: linux-arch@...r.kernel.org, Linux API <linux-api@...r.kernel.org>, linux-x86_64@...r.kernel.org, kernel-hardening@...ts.openwall.com, linux-mm@...ck.org, the arch/x86 maintainers <x86@...nel.org>, musl@...ts.openwall.com, libc-alpha@...rceware.org, linux-kernel@...r.kernel.org, Dave Hansen <dave.hansen@...el.com>, Kees Cook <keescook@...omium.org>, Andrei Vagin <avagin@...il.com> Subject: Re: [PATCH v3 1/3] x86: Implement arch_prctl(ARCH_VSYSCALL_CONTROL) to disable vsyscall * Andy Lutomirski: > Is there a reason you didn't just change the check earlier in the > function to: > > if (vsyscall_mode == NONE || current->mm->context.vsyscall_disabled) Andrei requested that I don't print anything if vsyscall was disabled. The original patch used a different message for better diagnostics. > Also, I still think the prctl should not be available if > vsyscall=emulate. Either we should fully implement it or we should > not implement. We could even do: > > pr_warn_once("userspace vsyscall hardening request ignored because you > have vsyscall=emulate. Unless you absolutely need vsyscall=emulate, > update your system to use vsyscall=xonly.\n"); > > and thus encourage good behavior. I think there is still some hardening applied even with vsyscall=emulate. The question is what is more important: the additional hardening, or clean, easily described behavior of the interface. Maybe ARCH_VSYSCALL_CONTROL could return different values based on to what degree it could disable vsyscall? The pr_warn_once does not seem particularly useful. Anyone who upgrades glibc and still uses vsyscall=emulate will see that, with no way to disable it. Thanks, Florian
Powered by blists - more mailing lists
Confused about mailing lists and their use? Read about mailing lists on Wikipedia and check out these guidelines on proper formatting of your messages.