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=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT 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 9C140C433DB for ; Tue, 16 Mar 2021 15:12:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 43856650AE for ; Tue, 16 Mar 2021 15:12:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237944AbhCPPMW (ORCPT ); Tue, 16 Mar 2021 11:12:22 -0400 Received: from mga01.intel.com ([192.55.52.88]:38747 "EHLO mga01.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235051AbhCPPLa (ORCPT ); Tue, 16 Mar 2021 11:11:30 -0400 IronPort-SDR: 625Z30NPD5ieLHlfiBMnQ7yqXkXHaLnUeKa2RUZXDTfoFuV5ppjQU5CVWBkW0Qp5W+cO4bqOKd et2HSYrLlCOg== X-IronPort-AV: E=McAfee;i="6000,8403,9924"; a="209212673" X-IronPort-AV: E=Sophos;i="5.81,251,1610438400"; d="scan'208";a="209212673" Received: from fmsmga008.fm.intel.com ([10.253.24.58]) by fmsmga101.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 16 Mar 2021 08:11:30 -0700 IronPort-SDR: 4f4emykvjjgpYOMp+uA/WqTf6P1Zvtb6Vy2ILdmfxE4eNCY4rzpUF+Pnmn6+FL8rUbs12Djvey wLGaCyDiJ8NQ== X-IronPort-AV: E=Sophos;i="5.81,251,1610438400"; d="scan'208";a="405570294" Received: from yyu32-desk.sc.intel.com ([143.183.136.146]) by fmsmga008-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 16 Mar 2021 08:11:30 -0700 From: Yu-cheng Yu To: 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 , Borislav Petkov , 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 Cc: Yu-cheng Yu Subject: [PATCH v23 15/28] x86/mm: Update maybe_mkwrite() for shadow stack Date: Tue, 16 Mar 2021 08:10:41 -0700 Message-Id: <20210316151054.5405-16-yu-cheng.yu@intel.com> X-Mailer: git-send-email 2.21.0 In-Reply-To: <20210316151054.5405-1-yu-cheng.yu@intel.com> References: <20210316151054.5405-1-yu-cheng.yu@intel.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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, and in page fault, _PAGE_DIRTY is restored and the shadow stack page is 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(+) diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index bdfecc17c2d3..102212025993 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -1945,12 +1945,16 @@ config X86_SGX config ARCH_HAS_SHADOW_STACK def_bool n +config ARCH_MAYBE_MKWRITE + def_bool n + config X86_CET prompt "Intel Control-flow protection for user-mode" def_bool n depends on AS_WRUSS depends on ARCH_HAS_SHADOW_STACK select ARCH_USES_HIGH_VMA_FLAGS + select ARCH_MAYBE_MKWRITE help Control-flow protection is a set of hardware features which place additional restrictions on indirect branches. These help diff --git a/arch/x86/mm/pgtable.c b/arch/x86/mm/pgtable.c index f6a9e2e36642..0f4fbf51a9fc 100644 --- a/arch/x86/mm/pgtable.c +++ b/arch/x86/mm/pgtable.c @@ -610,6 +610,24 @@ int pmdp_clear_flush_young(struct vm_area_struct *vma, } #endif +#ifdef CONFIG_ARCH_MAYBE_MKWRITE +pte_t arch_maybe_mkwrite(pte_t pte, struct vm_area_struct *vma) +{ + if (likely(vma->vm_flags & VM_SHSTK)) + pte = pte_mkwrite_shstk(pte); + return pte; +} + +#ifdef CONFIG_TRANSPARENT_HUGEPAGE +pmd_t arch_maybe_pmd_mkwrite(pmd_t pmd, struct vm_area_struct *vma) +{ + if (likely(vma->vm_flags & VM_SHSTK)) + pmd = pmd_mkwrite_shstk(pmd); + return pmd; +} +#endif /* CONFIG_TRANSPARENT_HUGEPAGE */ +#endif /* CONFIG_ARCH_MAYBE_MKWRITE */ + /** * reserve_top_address - reserves a hole in the top of kernel address space * @reserve - size of hole to reserve diff --git a/include/linux/mm.h b/include/linux/mm.h index a6c18c5752d6..af805ffde48e 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -997,6 +997,8 @@ static inline pte_t maybe_mkwrite(pte_t pte, struct vm_area_struct *vma) { if (likely(vma->vm_flags & VM_WRITE)) pte = pte_mkwrite(pte); + else + pte = arch_maybe_mkwrite(pte, vma); return pte; } diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h index 5e772392a379..cbd98484c4f1 100644 --- a/include/linux/pgtable.h +++ b/include/linux/pgtable.h @@ -1446,6 +1446,30 @@ static inline bool arch_has_pfn_modify_check(void) } #endif /* !_HAVE_ARCH_PFN_MODIFY_ALLOWED */ +#ifdef CONFIG_MMU +#ifdef CONFIG_ARCH_MAYBE_MKWRITE +pte_t arch_maybe_mkwrite(pte_t pte, struct vm_area_struct *vma); + +#ifdef CONFIG_TRANSPARENT_HUGEPAGE +pmd_t arch_maybe_pmd_mkwrite(pmd_t pmd, struct vm_area_struct *vma); +#endif /* CONFIG_TRANSPARENT_HUGEPAGE */ + +#else /* !CONFIG_ARCH_MAYBE_MKWRITE */ +static inline pte_t arch_maybe_mkwrite(pte_t pte, struct vm_area_struct *vma) +{ + return pte; +} + +#ifdef CONFIG_TRANSPARENT_HUGEPAGE +static inline pmd_t arch_maybe_pmd_mkwrite(pmd_t pmd, struct vm_area_struct *vma) +{ + return pmd; +} +#endif /* CONFIG_TRANSPARENT_HUGEPAGE */ + +#endif /* CONFIG_ARCH_MAYBE_MKWRITE */ +#endif /* CONFIG_MMU */ + /* * Architecture PAGE_KERNEL_* fallbacks * diff --git a/mm/huge_memory.c b/mm/huge_memory.c index ae907a9c2050..e79c1220a349 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -482,6 +482,8 @@ pmd_t maybe_pmd_mkwrite(pmd_t pmd, struct vm_area_struct *vma) { if (likely(vma->vm_flags & VM_WRITE)) pmd = pmd_mkwrite(pmd); + else + pmd = arch_maybe_pmd_mkwrite(pmd, vma); return pmd; } -- 2.21.0