Date: Fri, 22 Jan 2016 11:16:57 -0800 From: Laura Abbott <laura@...bott.name> To: kernel-hardening@...ts.openwall.com Cc: Ingo Molnar <mingo@...hat.com>, Kees Cook <keescook@...omium.org>, Andy Lutomirski <luto@...capital.net>, "H. Peter Anvin" <hpa@...or.com>, Michael Ellerman <mpe@...erman.id.au>, Mathias Krause <minipli@...glemail.com>, Thomas Gleixner <tglx@...utronix.de>, x86@...nel.org, Arnd Bergmann <arnd@...db.de>, PaX Team <pageexec@...email.hu>, Emese Revfy <re.emese@...il.com>, linux-kernel@...r.kernel.org, linux-arch <linux-arch@...r.kernel.org> Subject: Re: [PATCH v4 0/8] introduce post-init read-only memory On 1/22/16 9:19 AM, David Brown wrote: > On Tue, Jan 19, 2016 at 10:08:34AM -0800, Kees Cook wrote: > >> This introduces __ro_after_init as a way to mark such memory, and uses >> it on the x86 vDSO to kill an extant kernel exploitation method. Also >> adds a new kernel parameter to help debug future use and adds an lkdtm >> test to check the results. > > I've tested these patches on 32-bit ARM using the provoke-crashes > test. However, they do require CONFIG_ARM_KERNMEM_PERMS to be enabled > as well, which does incur additional memory usage. > > Do we want to consider making CONFIG_ARM_KERNMEM_PERMS default y for > security reasons, and just document that memory-constrained systems > may want to turn it off? > > I'll test the arm64 next. > > David Kees had previously pushed a patch to do so but it exposed a couple of underlying issues, mostly with low power paths (c.f. http://article.gmane.org/gmane.linux.ports.arm.kernel/471199, http://article.gmane.org/gmane.linux.kernel.mm/143489) Those will need to be all fixed up before this could be made default. Thanks, Laura
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