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=-9.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,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 4558CC352A2 for ; Wed, 5 Feb 2020 18:21:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1ED2121D7D for ; Wed, 5 Feb 2020 18:21:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727499AbgBESVm (ORCPT ); Wed, 5 Feb 2020 13:21:42 -0500 Received: from mga14.intel.com ([192.55.52.115]:20934 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727824AbgBESUa (ORCPT ); Wed, 5 Feb 2020 13:20:30 -0500 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga003.fm.intel.com ([10.253.24.29]) by fmsmga103.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 05 Feb 2020 10:20:28 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.70,406,1574150400"; d="scan'208";a="279447815" Received: from yyu32-desk.sc.intel.com ([143.183.136.146]) by FMSMGA003.fm.intel.com with ESMTP; 05 Feb 2020 10:20:28 -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 , x86-patch-review@intel.com Cc: Yu-cheng Yu Subject: [RFC PATCH v9 16/27] mm: Update can_follow_write_pte() for Shadow Stack Date: Wed, 5 Feb 2020 10:19:24 -0800 Message-Id: <20200205181935.3712-17-yu-cheng.yu@intel.com> X-Mailer: git-send-email 2.21.0 In-Reply-To: <20200205181935.3712-1-yu-cheng.yu@intel.com> References: <20200205181935.3712-1-yu-cheng.yu@intel.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-doc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-doc@vger.kernel.org Can_follow_write_pte() verifies that a read-only page is the task's own copy by ensuring the page has gone through faultin_page() and the PTE is Dirty. A Shadow Stack (SHSTK) PTE must be (read-only + _PAGE_DIRTY_HW). When a task does fork(), its SHSTK PTEs become (read-only + _PAGE_DIRTY_SW). This causes the next SHSTK access (i.e. CALL, RET, INCSSP) to trigger a fault; the page is then copied, and (read-only + _PAGE_DIRTY_HW) is restored. To update can_follow_write_pte() for SHSTK, introduce pte_exclusive(). It verifies a data PTE is Dirty and a SHSTK PTE has _PAGE_DIRTY_HW. Also rename can_follow_write_pte() to can_follow_write() to make its meaning clear; i.e. "Can we write to the page?", not "Is the PTE writable?" Also apply same changes to the huge memory case. Signed-off-by: Yu-cheng Yu --- arch/x86/mm/pgtable.c | 18 ++++++++++++++++++ include/asm-generic/pgtable.h | 12 ++++++++++++ mm/gup.c | 8 +++++--- mm/huge_memory.c | 8 +++++--- 4 files changed, 40 insertions(+), 6 deletions(-) diff --git a/arch/x86/mm/pgtable.c b/arch/x86/mm/pgtable.c index 3340b1d4e9da..fa8133f37918 100644 --- a/arch/x86/mm/pgtable.c +++ b/arch/x86/mm/pgtable.c @@ -887,6 +887,15 @@ inline pte_t pte_set_vma_features(pte_t pte, struct vm_area_struct *vma) return pte; } +inline bool pte_exclusive(pte_t pte, struct vm_area_struct *vma) +{ + if (vma->vm_flags & VM_SHSTK) + return pte_dirty_hw(pte); + else + return pte_dirty(pte); +} + +#ifdef CONFIG_TRANSPARENT_HUGEPAGE inline pmd_t pmd_set_vma_features(pmd_t pmd, struct vm_area_struct *vma) { if (vma->vm_flags & VM_SHSTK) @@ -894,4 +903,13 @@ inline pmd_t pmd_set_vma_features(pmd_t pmd, struct vm_area_struct *vma) else return pmd; } + +inline bool pmd_exclusive(pmd_t pmd, struct vm_area_struct *vma) +{ + if (vma->vm_flags & VM_SHSTK) + return pmd_dirty_hw(pmd); + else + return pmd_dirty(pmd); +} +#endif /* CONFIG_TRANSPARENT_HUGEPAGE */ #endif /* CONFIG_X86_INTEL_SHADOW_STACK_USER */ diff --git a/include/asm-generic/pgtable.h b/include/asm-generic/pgtable.h index a9df093fdf45..ae9a84fffc25 100644 --- a/include/asm-generic/pgtable.h +++ b/include/asm-generic/pgtable.h @@ -1202,18 +1202,30 @@ static inline pte_t pte_set_vma_features(pte_t pte, struct vm_area_struct *vma) return pte; } +static inline bool pte_exclusive(pte_t pte, struct vm_area_struct *vma) +{ + return pte_dirty(pte); +} + #ifdef CONFIG_TRANSPARENT_HUGEPAGE static inline pmd_t pmd_set_vma_features(pmd_t pmd, struct vm_area_struct *vma) { return pmd; } + +static inline bool pmd_exclusive(pmd_t pmd, struct vm_area_struct *vma) +{ + return pmd_dirty(pmd); +} #endif #else bool arch_copy_pte_mapping(vm_flags_t vm_flags); pte_t pte_set_vma_features(pte_t pte, struct vm_area_struct *vma); +bool pte_exclusive(pte_t pte, struct vm_area_struct *vma); #ifdef CONFIG_TRANSPARENT_HUGEPAGE pmd_t pmd_set_vma_features(pmd_t pmd, struct vm_area_struct *vma); +bool pmd_exclusive(pmd_t pmd, struct vm_area_struct *vma); #endif #endif #endif /* CONFIG_MMU */ diff --git a/mm/gup.c b/mm/gup.c index 7646bf993b25..d1dbfbde8443 100644 --- a/mm/gup.c +++ b/mm/gup.c @@ -164,10 +164,12 @@ static int follow_pfn_pte(struct vm_area_struct *vma, unsigned long address, * FOLL_FORCE can write to even unwritable pte's, but only * after we've gone through a COW cycle and they are dirty. */ -static inline bool can_follow_write_pte(pte_t pte, unsigned int flags) +static inline bool can_follow_write(pte_t pte, unsigned int flags, + struct vm_area_struct *vma) { return pte_write(pte) || - ((flags & FOLL_FORCE) && (flags & FOLL_COW) && pte_dirty(pte)); + ((flags & FOLL_FORCE) && (flags & FOLL_COW) && + pte_exclusive(pte, vma)); } static struct page *follow_page_pte(struct vm_area_struct *vma, @@ -205,7 +207,7 @@ static struct page *follow_page_pte(struct vm_area_struct *vma, } if ((flags & FOLL_NUMA) && pte_protnone(pte)) goto no_page; - if ((flags & FOLL_WRITE) && !can_follow_write_pte(pte, flags)) { + if ((flags & FOLL_WRITE) && !can_follow_write(pte, flags, vma)) { pte_unmap_unlock(ptep, ptl); return NULL; } diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 93ef368df2dd..baad346e9f4a 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -1469,10 +1469,12 @@ vm_fault_t do_huge_pmd_wp_page(struct vm_fault *vmf, pmd_t orig_pmd) * FOLL_FORCE can write to even unwritable pmd's, but only * after we've gone through a COW cycle and they are dirty. */ -static inline bool can_follow_write_pmd(pmd_t pmd, unsigned int flags) +static inline bool can_follow_write(pmd_t pmd, unsigned int flags, + struct vm_area_struct *vma) { return pmd_write(pmd) || - ((flags & FOLL_FORCE) && (flags & FOLL_COW) && pmd_dirty(pmd)); + ((flags & FOLL_FORCE) && (flags & FOLL_COW) && + pmd_exclusive(pmd, vma)); } struct page *follow_trans_huge_pmd(struct vm_area_struct *vma, @@ -1485,7 +1487,7 @@ struct page *follow_trans_huge_pmd(struct vm_area_struct *vma, assert_spin_locked(pmd_lockptr(mm, pmd)); - if (flags & FOLL_WRITE && !can_follow_write_pmd(*pmd, flags)) + if (flags & FOLL_WRITE && !can_follow_write(*pmd, flags, vma)) goto out; /* Avoid dumping huge zero page */ -- 2.21.0