Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755883AbbKYAeh (ORCPT ); Tue, 24 Nov 2015 19:34:37 -0500 Received: from mail-ob0-f171.google.com ([209.85.214.171]:34842 "EHLO mail-ob0-f171.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755395AbbKYAeZ (ORCPT ); Tue, 24 Nov 2015 19:34:25 -0500 MIME-Version: 1.0 In-Reply-To: <1448401114-24650-2-git-send-email-keescook@chromium.org> References: <1448401114-24650-1-git-send-email-keescook@chromium.org> <1448401114-24650-2-git-send-email-keescook@chromium.org> From: Andy Lutomirski Date: Tue, 24 Nov 2015 16:34:04 -0800 Message-ID: Subject: Re: [PATCH 1/2] x86: introduce post-init read-only memory To: Kees Cook Cc: linux-arch , Thomas Gleixner , Ingo Molnar , "linux-kernel@vger.kernel.org" , "kernel-hardening@lists.openwall.com" , Arnd Bergmann , X86 ML , "H. Peter Anvin" , Michael Ellerman Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1253 Lines: 26 On Nov 24, 2015 1:38 PM, "Kees Cook" wrote: > > One of the easiest ways to protect the kernel from attack is to reduce > the internal attack surface exposed when a "write" flaw is available. By > making as much of the kernel read-only as possible, we reduce the > attack surface. > > Many things are written to only during __init, and never changed > again. These cannot be made "const" since the compiler will do the wrong > thing (we do actually need to write to them). Instead, move these items > into a memory region that will be made read-only during mark_rodata_ro() > which happens after all kernel __init code has finished. > > This introduces __read_only as a way to mark such memory, and adds some > documentation about the existing __read_mostly marking. Obligatory bikeshed: __ro_after_init, please. It's barely longer, and it directly explains what's going on. __read_only makes me think that it's really read-only and could, for example, actually be in ROM. --Andy -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/