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 0489BC433DB for ; Wed, 10 Feb 2021 18:16:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C6E0C64DC3 for ; Wed, 10 Feb 2021 18:16:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233955AbhBJSPo (ORCPT ); Wed, 10 Feb 2021 13:15:44 -0500 Received: from mga17.intel.com ([192.55.52.151]:29594 "EHLO mga17.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233655AbhBJSDT (ORCPT ); Wed, 10 Feb 2021 13:03:19 -0500 IronPort-SDR: VYhl8ScBPbo5efFQutLrk7nlByT0bcZMox3bSmaRMPdm4b+w5OpzDeHPBYQEea0I2KDjFJd9D6 VpJXtm+dKU2g== X-IronPort-AV: E=McAfee;i="6000,8403,9891"; a="161872851" X-IronPort-AV: E=Sophos;i="5.81,168,1610438400"; d="scan'208";a="161872851" Received: from fmsmga002.fm.intel.com ([10.253.24.26]) by fmsmga107.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 10 Feb 2021 09:58:02 -0800 IronPort-SDR: kQqWt2a8RjAi1PhpD/wmgVs1wkXVv8T0txMyUn1u6L8EieiD4974jlCCQG1eSmKAFvzl6mum6N YZRQ/LAcBhYQ== X-IronPort-AV: E=Sophos;i="5.81,168,1610438400"; d="scan'208";a="421140763" Received: from yyu32-desk.sc.intel.com ([143.183.136.146]) by fmsmga002-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 10 Feb 2021 09:58:02 -0800 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 , Cc: Yu-cheng Yu Subject: [PATCH v20 14/25] x86/mm: Update maybe_mkwrite() for shadow stack Date: Wed, 10 Feb 2021 09:56:52 -0800 Message-Id: <20210210175703.12492-15-yu-cheng.yu@intel.com> X-Mailer: git-send-email 2.21.0 In-Reply-To: <20210210175703.12492-1-yu-cheng.yu@intel.com> References: <20210210175703.12492-1-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 1138b5fa9b4f..4f0d159a8654 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -1955,6 +1955,9 @@ 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 @@ -1962,6 +1965,7 @@ config X86_CET 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 7be5f8b874aa..abd756e426fc 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -993,6 +993,8 @@ 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 8fcdfa52eb4b..d8452218d09b 100644 --- a/include/linux/pgtable.h +++ b/include/linux/pgtable.h @@ -1439,6 +1439,30 @@ 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 91ca9b103ee5..ac651d529dbe 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -478,6 +478,8 @@ 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