From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2CF78C43381 for ; Wed, 17 Mar 2021 15:57:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id CAF3064F5E for ; Wed, 17 Mar 2021 15:57:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232008AbhCQP4q (ORCPT ); Wed, 17 Mar 2021 11:56:46 -0400 Received: from mail.skyhub.de ([5.9.137.197]:37704 "EHLO mail.skyhub.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231878AbhCQP4Q (ORCPT ); Wed, 17 Mar 2021 11:56:16 -0400 Received: from zn.tnic (p200300ec2f094a000fa04028afd60743.dip0.t-ipconnect.de [IPv6:2003:ec:2f09:4a00:fa0:4028:afd6:743]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.skyhub.de (SuperMail on ZX Spectrum 128k) with ESMTPSA id 9165B1EC056D; Wed, 17 Mar 2021 16:56:11 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=alien8.de; s=dkim; t=1615996571; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:in-reply-to:in-reply-to: references:references; bh=jKbFwAc3tzTE1JguNnjYbxfLAPfDUjYL9hlZmr/NLIY=; b=LzKzQSFwh9U2Yq/59xL+M9GfQEid0oY5SAwuAjSVqtWer0V2MII7mfaPgF0EsI2g0sJ6gv +Z97J++b/vmGzsGs5pL0DpeCT9X4bAPjmwFtbMdlOn/MKdXhTpwHa8GX1OsVrVesgCzXHG gkz0Ae20Iigp/0Szx2YiOTY+d2tPgvI= Date: Wed, 17 Mar 2021 16:56:08 +0100 From: Borislav Petkov To: Yu-cheng Yu Cc: x86@kernel.org, "H. Peter Anvin" , Thomas Gleixner , Ingo Molnar , linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-mm@kvack.org, linux-arch@vger.kernel.org, linux-api@vger.kernel.org, Arnd Bergmann , Andy Lutomirski , Balbir Singh , Cyrill Gorcunov , Dave Hansen , Eugene Syromiatnikov , Florian Weimer , "H.J. Lu" , Jann Horn , Jonathan Corbet , Kees Cook , Mike Kravetz , Nadav Amit , Oleg Nesterov , Pavel Machek , Peter Zijlstra , Randy Dunlap , "Ravi V. Shankar" , Vedvyas Shanbhogue , Dave Martin , Weijiang Yang , Pengfei Xu , Haitao Huang Subject: Re: [PATCH v23 15/28] x86/mm: Update maybe_mkwrite() for shadow stack Message-ID: <20210317155608.GB25069@zn.tnic> References: <20210316151054.5405-1-yu-cheng.yu@intel.com> <20210316151054.5405-16-yu-cheng.yu@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20210316151054.5405-16-yu-cheng.yu@intel.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Mar 16, 2021 at 08:10:41AM -0700, Yu-cheng Yu wrote: > When serving a page fault, maybe_mkwrite() makes a PTE writable if its vma > has VM_WRITE. > > A shadow stack vma has VM_SHSTK. Its PTEs have _PAGE_DIRTY, but not > _PAGE_WRITE. In fork(), _PAGE_DIRTY is cleared to effect copy-on-write, to cause > and in page fault, _PAGE_DIRTY is restored and the shadow stack page is in the page fault handler... > writable again. > > Update maybe_mkwrite() by introducing arch_maybe_mkwrite(), which sets > _PAGE_DIRTY for a shadow stack PTE. > > Apply the same changes to maybe_pmd_mkwrite(). > > Signed-off-by: Yu-cheng Yu > Reviewed-by: Kees Cook > --- > arch/x86/Kconfig | 4 ++++ > arch/x86/mm/pgtable.c | 18 ++++++++++++++++++ > include/linux/mm.h | 2 ++ > include/linux/pgtable.h | 24 ++++++++++++++++++++++++ > mm/huge_memory.c | 2 ++ > 5 files changed, 50 insertions(+) Looks straightforward to me but I guess it needs a mm person's ack. -- Regards/Gruss, Boris. https://people.kernel.org/tglx/notes-about-netiquette