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=-3.9 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no 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 7EB54C2BA1A for ; Tue, 7 Apr 2020 03:06:12 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 41A80215A4 for ; Tue, 7 Apr 2020 03:06:12 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="ShA4Hhfn" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 41A80215A4 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux-foundation.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id EC2A28E0031; Mon, 6 Apr 2020 23:06:11 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id EA4F88E0001; Mon, 6 Apr 2020 23:06:11 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id DD6D48E0031; Mon, 6 Apr 2020 23:06:11 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0129.hostedemail.com [216.40.44.129]) by kanga.kvack.org (Postfix) with ESMTP id C28F38E0001 for ; Mon, 6 Apr 2020 23:06:11 -0400 (EDT) Received: from smtpin21.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id 832C2A8C4 for ; Tue, 7 Apr 2020 03:06:11 +0000 (UTC) X-FDA: 76679570142.21.key10_7037aa48a8060 X-HE-Tag: key10_7037aa48a8060 X-Filterd-Recvd-Size: 5688 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf45.hostedemail.com (Postfix) with ESMTP for ; Tue, 7 Apr 2020 03:06:10 +0000 (UTC) Received: from localhost.localdomain (c-73-231-172-41.hsd1.ca.comcast.net [73.231.172.41]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 8BFD820BED; Tue, 7 Apr 2020 03:06:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1586228770; bh=ImVhuNLuT27fsCpSHnf+VbupQ4ADrPr12xB/4dbzDPI=; h=Date:From:To:Subject:In-Reply-To:From; b=ShA4HhfnOwHixhngqdO9WaUFDN2si0Ri9ITK9utL6g8aZXR+6qlLtHRdMZTyVwwsB jJM5e8Kf7TTuXmMcxdE2KIFzXoEqijVekK/hle/LHHOmfRIqH5PSp7Vul/WudN8P3G kl42PJkLtGkxgIp3Iceb5hO3ILaCHlOJZAbIK0XU= Date: Mon, 06 Apr 2020 20:06:09 -0700 From: Andrew Morton To: aarcange@redhat.com, akpm@linux-foundation.org, bgeffon@google.com, bobbypowers@gmail.com, cracauer@cons.org, david@redhat.com, dgilbert@redhat.com, dplotnikov@virtuozzo.com, gokhale2@llnl.gov, hannes@cmpxchg.org, hughd@google.com, jglisse@redhat.com, kirill@shutemov.name, linux-mm@kvack.org, mcfadden8@llnl.gov, mgorman@suse.de, mike.kravetz@oracle.com, mm-commits@vger.kernel.org, peterx@redhat.com, riel@redhat.com, rppt@linux.vnet.ibm.com, shli@fb.com, torvalds@linux-foundation.org, xemul@openvz.org Subject: [patch 044/166] userfaultfd: wp: support write protection for userfault vma range Message-ID: <20200407030609.Ml781XebP%akpm@linux-foundation.org> In-Reply-To: <20200406200254.a69ebd9e08c4074e41ddebaf@linux-foundation.org> User-Agent: s-nail v14.8.16 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: From: Shaohua Li Subject: userfaultfd: wp: support write protection for userfault vma range Add API to enable/disable writeprotect a vma range. Unlike mprotect, this doesn't split/merge vmas. [peterx@redhat.com: - 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 - replace find_dst_vma with vma_find_uffd] Link: http://lkml.kernel.org/r/20200220163112.11409-13-peterx@redhat.com Signed-off-by: Shaohua Li Signed-off-by: Andrea Arcangeli Signed-off-by: Peter Xu Reviewed-by: Jerome Glisse Reviewed-by: Mike Rapoport Cc: Andrea Arcangeli Cc: Rik van Riel Cc: Kirill A. Shutemov Cc: Mel Gorman Cc: Hugh Dickins Cc: Johannes Weiner Cc: Bobby Powers Cc: Brian Geffon Cc: David Hildenbrand Cc: Denis Plotnikov Cc: "Dr . David Alan Gilbert" Cc: Martin Cracauer Cc: Marty McFadden Cc: Maya Gokhale Cc: Mike Kravetz Cc: Pavel Emelyanov Signed-off-by: Andrew Morton --- include/linux/userfaultfd_k.h | 3 + mm/userfaultfd.c | 54 ++++++++++++++++++++++++++++++++ 2 files changed, 57 insertions(+) --- a/include/linux/userfaultfd_k.h~userfaultfd-wp-support-write-protection-for-userfault-vma-range +++ a/include/linux/userfaultfd_k.h @@ -41,6 +41,9 @@ extern ssize_t mfill_zeropage(struct 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, --- a/mm/userfaultfd.c~userfaultfd-wp-support-write-protection-for-userfault-vma-range +++ a/mm/userfaultfd.c @@ -638,3 +638,57 @@ ssize_t mfill_zeropage(struct mm_struct { 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 = find_dst_vma(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; +} _