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=-7.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED autolearn=ham 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 EA217C43381 for ; Wed, 20 Mar 2019 02:09:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C63492183E for ; Wed, 20 Mar 2019 02:09:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727893AbfCTCJh (ORCPT ); Tue, 19 Mar 2019 22:09:37 -0400 Received: from mx1.redhat.com ([209.132.183.28]:55758 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727017AbfCTCJg (ORCPT ); Tue, 19 Mar 2019 22:09:36 -0400 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 6CDDC308FC22; Wed, 20 Mar 2019 02:09:36 +0000 (UTC) Received: from xz-x1.nay.redhat.com (dhcp-14-116.nay.redhat.com [10.66.14.116]) by smtp.corp.redhat.com (Postfix) with ESMTP id 3A2446014C; Wed, 20 Mar 2019 02:09:27 +0000 (UTC) From: Peter Xu To: linux-mm@kvack.org, linux-kernel@vger.kernel.org Cc: David Hildenbrand , Hugh Dickins , Maya Gokhale , Jerome Glisse , Pavel Emelyanov , Johannes Weiner , peterx@redhat.com, Martin Cracauer , Shaohua Li , Andrea Arcangeli , Mike Kravetz , Denis Plotnikov , Mike Rapoport , Marty McFadden , Mel Gorman , "Kirill A . Shutemov" , "Dr . David Alan Gilbert" , Rik van Riel Subject: [PATCH v3 20/28] userfaultfd: wp: support write protection for userfault vma range Date: Wed, 20 Mar 2019 10:06:34 +0800 Message-Id: <20190320020642.4000-21-peterx@redhat.com> In-Reply-To: <20190320020642.4000-1-peterx@redhat.com> References: <20190320020642.4000-1-peterx@redhat.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.43]); Wed, 20 Mar 2019 02:09:36 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Shaohua Li Add API to enable/disable writeprotect a vma range. Unlike mprotect, this doesn't split/merge vmas. Cc: Andrea Arcangeli Cc: Rik van Riel Cc: Kirill A. Shutemov Cc: Mel Gorman Cc: Hugh Dickins Cc: Johannes Weiner Signed-off-by: Shaohua Li Signed-off-by: Andrea Arcangeli [peterx: - use the helper to find VMA; - return -ENOENT if not found to match mcopy case; - use the new MM_CP_UFFD_WP* flags for change_protection - check against mmap_changing for failures] Reviewed-by: Jerome Glisse Reviewed-by: Mike Rapoport Signed-off-by: Peter Xu --- include/linux/userfaultfd_k.h | 3 ++ mm/userfaultfd.c | 54 +++++++++++++++++++++++++++++++++++ 2 files changed, 57 insertions(+) diff --git a/include/linux/userfaultfd_k.h b/include/linux/userfaultfd_k.h index 765ce884cec0..8f6e6ed544fb 100644 --- a/include/linux/userfaultfd_k.h +++ b/include/linux/userfaultfd_k.h @@ -39,6 +39,9 @@ extern ssize_t mfill_zeropage(struct mm_struct *dst_mm, unsigned long dst_start, unsigned long len, bool *mmap_changing); +extern int mwriteprotect_range(struct mm_struct *dst_mm, + unsigned long start, unsigned long len, + bool enable_wp, bool *mmap_changing); /* mm helpers */ static inline bool is_mergeable_vm_userfaultfd_ctx(struct vm_area_struct *vma, diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c index 2606409572b2..70cea2ff3960 100644 --- a/mm/userfaultfd.c +++ b/mm/userfaultfd.c @@ -639,3 +639,57 @@ ssize_t mfill_zeropage(struct mm_struct *dst_mm, unsigned long start, { return __mcopy_atomic(dst_mm, start, 0, len, true, mmap_changing, 0); } + +int mwriteprotect_range(struct mm_struct *dst_mm, unsigned long start, + unsigned long len, bool enable_wp, bool *mmap_changing) +{ + struct vm_area_struct *dst_vma; + pgprot_t newprot; + int err; + + /* + * Sanitize the command parameters: + */ + BUG_ON(start & ~PAGE_MASK); + BUG_ON(len & ~PAGE_MASK); + + /* Does the address range wrap, or is the span zero-sized? */ + BUG_ON(start + len <= start); + + down_read(&dst_mm->mmap_sem); + + /* + * If memory mappings are changing because of non-cooperative + * operation (e.g. mremap) running in parallel, bail out and + * request the user to retry later + */ + err = -EAGAIN; + if (mmap_changing && READ_ONCE(*mmap_changing)) + goto out_unlock; + + err = -ENOENT; + dst_vma = vma_find_uffd(dst_mm, start, len); + /* + * Make sure the vma is not shared, that the dst range is + * both valid and fully within a single existing vma. + */ + if (!dst_vma || (dst_vma->vm_flags & VM_SHARED)) + goto out_unlock; + if (!userfaultfd_wp(dst_vma)) + goto out_unlock; + if (!vma_is_anonymous(dst_vma)) + goto out_unlock; + + if (enable_wp) + newprot = vm_get_page_prot(dst_vma->vm_flags & ~(VM_WRITE)); + else + newprot = vm_get_page_prot(dst_vma->vm_flags); + + change_protection(dst_vma, start, start + len, newprot, + enable_wp ? MM_CP_UFFD_WP : MM_CP_UFFD_WP_RESOLVE); + + err = 0; +out_unlock: + up_read(&dst_mm->mmap_sem); + return err; +} -- 2.17.1