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=-3.5 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,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 C5F41C433DB for ; Mon, 25 Jan 2021 17:01:28 +0000 (UTC) Received: from ml01.01.org (ml01.01.org [198.145.21.10]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 8AB802223E for ; Mon, 25 Jan 2021 17:01:28 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 8AB802223E Authentication-Results: mail.kernel.org; dmarc=fail (p=quarantine dis=none) header.from=suse.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-nvdimm-bounces@lists.01.org Received: from ml01.vlan13.01.org (localhost [IPv6:::1]) by ml01.01.org (Postfix) with ESMTP id 28E70100EBBAB; Mon, 25 Jan 2021 09:01:28 -0800 (PST) Received-SPF: Pass (mailfrom) identity=mailfrom; client-ip=195.135.220.15; helo=mx2.suse.de; envelope-from=mhocko@suse.com; receiver= Received: from mx2.suse.de (mx2.suse.de [195.135.220.15]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ml01.01.org (Postfix) with ESMTPS id 185F1100EBBA2 for ; Mon, 25 Jan 2021 09:01:24 -0800 (PST) X-Virus-Scanned: by amavisd-new at test-mx.suse.de DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1611594083; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=Vhg3ZuXdxoTlKTck/oJokadNWML4/97msM+l8PPW1KQ=; b=ekr2Ky1dZoRqi6ycGHVcexZtgRdu4MDaulztS70s8hHeoDI4yFro/m5BDFgGJjh7XxGRcq OdP/PJmINTbjpgXdHy4MQI8TR0XvbgfyJK1DIbaE0IJT4yiv7duwl7QsRrI2lC9GQ+4fV8 Fl+xfN24YgfeX+iBNh+IKs3bk8PeCaI= Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 4907CAD7A; Mon, 25 Jan 2021 17:01:23 +0000 (UTC) Date: Mon, 25 Jan 2021 18:01:22 +0100 From: Michal Hocko To: Mike Rapoport Subject: Re: [PATCH v16 06/11] mm: introduce memfd_secret system call to create "secret" memory areas Message-ID: <20210125170122.GU827@dhcp22.suse.cz> References: <20210121122723.3446-1-rppt@kernel.org> <20210121122723.3446-7-rppt@kernel.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20210121122723.3446-7-rppt@kernel.org> Message-ID-Hash: HAJA6PQQE4Q2CGFLMYNXFZ7C6GLYRQV6 X-Message-ID-Hash: HAJA6PQQE4Q2CGFLMYNXFZ7C6GLYRQV6 X-MailFrom: mhocko@suse.com X-Mailman-Rule-Hits: nonmember-moderation X-Mailman-Rule-Misses: dmarc-mitigation; no-senders; approved; emergency; loop; banned-address; member-moderation CC: Andrew Morton , Alexander Viro , Andy Lutomirski , Arnd Bergmann , Borislav Petkov , Catalin Marinas , Christopher Lameter , Dave Hansen , David Hildenbrand , Elena Reshetova , "H. Peter Anvin" , Ingo Molnar , James Bottomley , "Kirill A. Shutemov" , Matthew Wilcox , Mark Rutland , Mike Rapoport , Michael Kerrisk , Palmer Dabbelt , Paul Walmsley , Peter Zijlstra , Rick Edgecombe , Roman Gushchin , Shakeel Butt , Shuah Khan , Thomas Gleixner , Tycho Andersen , Will Deacon , linux-api@vger.kernel.org, linux-arch@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-nvdimm@lists.01.org, linux-riscv@lists.infradead.org, x86@kernel.org, Hagen Paul Pfeifer , Palmer Dabbelt X-Mailman-Version: 3.1.1 Precedence: list List-Id: "Linux-nvdimm developer list." Archived-At: List-Archive: List-Help: List-Post: List-Subscribe: List-Unsubscribe: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit On Thu 21-01-21 14:27:18, Mike Rapoport wrote: > From: Mike Rapoport > > Introduce "memfd_secret" system call with the ability to create memory > areas visible only in the context of the owning process and not mapped not > only to other processes but in the kernel page tables as well. > > The user will create a file descriptor using the memfd_secret() system > call. The memory areas created by mmap() calls from this file descriptor > will be unmapped from the kernel direct map and they will be only mapped in > the page table of the owning mm. > > The secret memory remains accessible in the process context using uaccess > primitives, but it is not accessible using direct/linear map addresses. > > Functions in the follow_page()/get_user_page() family will refuse to return > a page that belongs to the secret memory area. > > A page that was a part of the secret memory area is cleared when it is > freed. > > The following example demonstrates creation of a secret mapping (error > handling is omitted): > > fd = memfd_secret(0); > ftruncate(fd, MAP_SIZE); > ptr = mmap(NULL, MAP_SIZE, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0); I do not see any access control or permission model for this feature. Is this feature generally safe to anybody? -- Michal Hocko SUSE Labs _______________________________________________ Linux-nvdimm mailing list -- linux-nvdimm@lists.01.org To unsubscribe send an email to linux-nvdimm-leave@lists.01.org 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=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS 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 65056C433E0 for ; Mon, 25 Jan 2021 17:03:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2772622511 for ; Mon, 25 Jan 2021 17:03:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730370AbhAYRDV (ORCPT ); Mon, 25 Jan 2021 12:03:21 -0500 Received: from mx2.suse.de ([195.135.220.15]:50368 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729996AbhAYRCL (ORCPT ); Mon, 25 Jan 2021 12:02:11 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1611594083; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=Vhg3ZuXdxoTlKTck/oJokadNWML4/97msM+l8PPW1KQ=; b=ekr2Ky1dZoRqi6ycGHVcexZtgRdu4MDaulztS70s8hHeoDI4yFro/m5BDFgGJjh7XxGRcq OdP/PJmINTbjpgXdHy4MQI8TR0XvbgfyJK1DIbaE0IJT4yiv7duwl7QsRrI2lC9GQ+4fV8 Fl+xfN24YgfeX+iBNh+IKs3bk8PeCaI= Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 4907CAD7A; Mon, 25 Jan 2021 17:01:23 +0000 (UTC) Date: Mon, 25 Jan 2021 18:01:22 +0100 From: Michal Hocko To: Mike Rapoport Cc: Andrew Morton , Alexander Viro , Andy Lutomirski , Arnd Bergmann , Borislav Petkov , Catalin Marinas , Christopher Lameter , Dan Williams , Dave Hansen , David Hildenbrand , Elena Reshetova , "H. Peter Anvin" , Ingo Molnar , James Bottomley , "Kirill A. Shutemov" , Matthew Wilcox , Mark Rutland , Mike Rapoport , Michael Kerrisk , Palmer Dabbelt , Paul Walmsley , Peter Zijlstra , Rick Edgecombe , Roman Gushchin , Shakeel Butt , Shuah Khan , Thomas Gleixner , Tycho Andersen , Will Deacon , linux-api@vger.kernel.org, linux-arch@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-nvdimm@lists.01.org, linux-riscv@lists.infradead.org, x86@kernel.org, Hagen Paul Pfeifer , Palmer Dabbelt Subject: Re: [PATCH v16 06/11] mm: introduce memfd_secret system call to create "secret" memory areas Message-ID: <20210125170122.GU827@dhcp22.suse.cz> References: <20210121122723.3446-1-rppt@kernel.org> <20210121122723.3446-7-rppt@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210121122723.3446-7-rppt@kernel.org> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu 21-01-21 14:27:18, Mike Rapoport wrote: > From: Mike Rapoport > > Introduce "memfd_secret" system call with the ability to create memory > areas visible only in the context of the owning process and not mapped not > only to other processes but in the kernel page tables as well. > > The user will create a file descriptor using the memfd_secret() system > call. The memory areas created by mmap() calls from this file descriptor > will be unmapped from the kernel direct map and they will be only mapped in > the page table of the owning mm. > > The secret memory remains accessible in the process context using uaccess > primitives, but it is not accessible using direct/linear map addresses. > > Functions in the follow_page()/get_user_page() family will refuse to return > a page that belongs to the secret memory area. > > A page that was a part of the secret memory area is cleared when it is > freed. > > The following example demonstrates creation of a secret mapping (error > handling is omitted): > > fd = memfd_secret(0); > ftruncate(fd, MAP_SIZE); > ptr = mmap(NULL, MAP_SIZE, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0); I do not see any access control or permission model for this feature. Is this feature generally safe to anybody? -- Michal Hocko SUSE Labs 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=-4.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, 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 175FAC433E6 for ; Mon, 25 Jan 2021 17:01:48 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id CF9632223E for ; Mon, 25 Jan 2021 17:01:47 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org CF9632223E Authentication-Results: mail.kernel.org; dmarc=fail (p=quarantine dis=none) header.from=suse.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-riscv-bounces+linux-riscv=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=merlin.20170209; h=Sender:Content-Transfer-Encoding: Content-Type:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References:Message-ID: Subject:To:From:Date:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=LzzeF02Hb4b5GiQsdIJ9Bdv+vuMU/FJ1ac2qd+n1hrk=; b=2TT9cIzMFtA2rE+4CaMyivLaW LRNoclMadunwwarEHFEtVlve1OY1Cm42dg77X+yhLqp++2cytKeb4VpcwSnpjA0BztD6sxDau0sXe v3O5TuCHCMNGQaI4mOxk062RJLgCujdT6RMD3JnZR6D4UkKPnignr/Ox2LOap+Azy6/KMJUbprRH/ O1XaZkqFjXWF0PE1yaTt8QjMVNV1DjNH6afSy4/A19lkgNlq6/3fCNPKO+rqa73KF/PS912jd/+5m ATHrHD0kydcIK96S+Dj1YarBBBja1sWCqlHSVmhEPKv1Tc2Ra9bA3d3XbzPiLRM+4ya/rQ1ARMu/s OtcHdne1g==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1l45F5-0005i5-6L; Mon, 25 Jan 2021 17:01:31 +0000 Received: from mx2.suse.de ([195.135.220.15]) by merlin.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1l45Ez-0005fQ-1P; Mon, 25 Jan 2021 17:01:26 +0000 X-Virus-Scanned: by amavisd-new at test-mx.suse.de DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1611594083; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=Vhg3ZuXdxoTlKTck/oJokadNWML4/97msM+l8PPW1KQ=; b=ekr2Ky1dZoRqi6ycGHVcexZtgRdu4MDaulztS70s8hHeoDI4yFro/m5BDFgGJjh7XxGRcq OdP/PJmINTbjpgXdHy4MQI8TR0XvbgfyJK1DIbaE0IJT4yiv7duwl7QsRrI2lC9GQ+4fV8 Fl+xfN24YgfeX+iBNh+IKs3bk8PeCaI= Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 4907CAD7A; Mon, 25 Jan 2021 17:01:23 +0000 (UTC) Date: Mon, 25 Jan 2021 18:01:22 +0100 From: Michal Hocko To: Mike Rapoport Subject: Re: [PATCH v16 06/11] mm: introduce memfd_secret system call to create "secret" memory areas Message-ID: <20210125170122.GU827@dhcp22.suse.cz> References: <20210121122723.3446-1-rppt@kernel.org> <20210121122723.3446-7-rppt@kernel.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20210121122723.3446-7-rppt@kernel.org> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210125_120125_191952_F54BD2AB X-CRM114-Status: GOOD ( 19.45 ) X-BeenThere: linux-riscv@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Mark Rutland , David Hildenbrand , Peter Zijlstra , Catalin Marinas , Dave Hansen , linux-mm@kvack.org, linux-kselftest@vger.kernel.org, "H. Peter Anvin" , Christopher Lameter , Shuah Khan , Thomas Gleixner , Elena Reshetova , linux-arch@vger.kernel.org, Tycho Andersen , linux-nvdimm@lists.01.org, Will Deacon , x86@kernel.org, Matthew Wilcox , Mike Rapoport , Ingo Molnar , Michael Kerrisk , Palmer Dabbelt , Arnd Bergmann , James Bottomley , Hagen Paul Pfeifer , Borislav Petkov , Alexander Viro , Andy Lutomirski , Paul Walmsley , "Kirill A. Shutemov" , Dan Williams , linux-arm-kernel@lists.infradead.org, linux-api@vger.kernel.org, linux-kernel@vger.kernel.org, linux-riscv@lists.infradead.org, Palmer Dabbelt , linux-fsdevel@vger.kernel.org, Shakeel Butt , Andrew Morton , Rick Edgecombe , Roman Gushchin Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-riscv" Errors-To: linux-riscv-bounces+linux-riscv=archiver.kernel.org@lists.infradead.org On Thu 21-01-21 14:27:18, Mike Rapoport wrote: > From: Mike Rapoport > > Introduce "memfd_secret" system call with the ability to create memory > areas visible only in the context of the owning process and not mapped not > only to other processes but in the kernel page tables as well. > > The user will create a file descriptor using the memfd_secret() system > call. The memory areas created by mmap() calls from this file descriptor > will be unmapped from the kernel direct map and they will be only mapped in > the page table of the owning mm. > > The secret memory remains accessible in the process context using uaccess > primitives, but it is not accessible using direct/linear map addresses. > > Functions in the follow_page()/get_user_page() family will refuse to return > a page that belongs to the secret memory area. > > A page that was a part of the secret memory area is cleared when it is > freed. > > The following example demonstrates creation of a secret mapping (error > handling is omitted): > > fd = memfd_secret(0); > ftruncate(fd, MAP_SIZE); > ptr = mmap(NULL, MAP_SIZE, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0); I do not see any access control or permission model for this feature. Is this feature generally safe to anybody? -- Michal Hocko SUSE Labs _______________________________________________ linux-riscv mailing list linux-riscv@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-riscv 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=-4.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, 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 15AC5C433DB for ; Mon, 25 Jan 2021 17:03:02 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id B8E582223E for ; Mon, 25 Jan 2021 17:02:59 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B8E582223E Authentication-Results: mail.kernel.org; dmarc=fail (p=quarantine dis=none) header.from=suse.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=merlin.20170209; h=Sender:Content-Transfer-Encoding: Content-Type:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References:Message-ID: Subject:To:From:Date:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=+q2WOFDdgGU+mZ0qDHSclrLNHC2VkC/wdLMG3XjFi2Y=; b=C54ruh++p1M1LUkjIzXRud1yd teeIO0KJxH1Zv6qVzTuPmq/01AdrTFQgfjbJDVj6JBHSf6KEkPek/4MlCNhQzWTVLQgFHpUI7HT2U smgujQIYqcWUdCe5BOcUSX86ubnJhQSYmk9/D0OgVn4NrBNzKD1ONk5EvX2E5nmmGeyo/vdkzKio7 N+eUWBYeG1mRpmV7pw2P+qC8wZdwp+XfApodmtZB+AwmBWsjQZ0iudwgRKGoX7I6maJT5AMoGYWH+ 4y7bTvccPmPJyKMZv4JgJzDe2N0FGkp5H76llWWqT3erfNMCZL8fpzXGyAvSuNA7klm0rzyUztyls w4gjT/jOA==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1l45F3-0005hJ-0v; Mon, 25 Jan 2021 17:01:29 +0000 Received: from mx2.suse.de ([195.135.220.15]) by merlin.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1l45Ez-0005fQ-1P; Mon, 25 Jan 2021 17:01:26 +0000 X-Virus-Scanned: by amavisd-new at test-mx.suse.de DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1611594083; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=Vhg3ZuXdxoTlKTck/oJokadNWML4/97msM+l8PPW1KQ=; b=ekr2Ky1dZoRqi6ycGHVcexZtgRdu4MDaulztS70s8hHeoDI4yFro/m5BDFgGJjh7XxGRcq OdP/PJmINTbjpgXdHy4MQI8TR0XvbgfyJK1DIbaE0IJT4yiv7duwl7QsRrI2lC9GQ+4fV8 Fl+xfN24YgfeX+iBNh+IKs3bk8PeCaI= Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 4907CAD7A; Mon, 25 Jan 2021 17:01:23 +0000 (UTC) Date: Mon, 25 Jan 2021 18:01:22 +0100 From: Michal Hocko To: Mike Rapoport Subject: Re: [PATCH v16 06/11] mm: introduce memfd_secret system call to create "secret" memory areas Message-ID: <20210125170122.GU827@dhcp22.suse.cz> References: <20210121122723.3446-1-rppt@kernel.org> <20210121122723.3446-7-rppt@kernel.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20210121122723.3446-7-rppt@kernel.org> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210125_120125_191952_F54BD2AB X-CRM114-Status: GOOD ( 19.45 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Mark Rutland , David Hildenbrand , Peter Zijlstra , Catalin Marinas , Dave Hansen , linux-mm@kvack.org, linux-kselftest@vger.kernel.org, "H. Peter Anvin" , Christopher Lameter , Shuah Khan , Thomas Gleixner , Elena Reshetova , linux-arch@vger.kernel.org, Tycho Andersen , linux-nvdimm@lists.01.org, Will Deacon , x86@kernel.org, Matthew Wilcox , Mike Rapoport , Ingo Molnar , Michael Kerrisk , Palmer Dabbelt , Arnd Bergmann , James Bottomley , Hagen Paul Pfeifer , Borislav Petkov , Alexander Viro , Andy Lutomirski , Paul Walmsley , "Kirill A. Shutemov" , Dan Williams , linux-arm-kernel@lists.infradead.org, linux-api@vger.kernel.org, linux-kernel@vger.kernel.org, linux-riscv@lists.infradead.org, Palmer Dabbelt , linux-fsdevel@vger.kernel.org, Shakeel Butt , Andrew Morton , Rick Edgecombe , Roman Gushchin Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Thu 21-01-21 14:27:18, Mike Rapoport wrote: > From: Mike Rapoport > > Introduce "memfd_secret" system call with the ability to create memory > areas visible only in the context of the owning process and not mapped not > only to other processes but in the kernel page tables as well. > > The user will create a file descriptor using the memfd_secret() system > call. The memory areas created by mmap() calls from this file descriptor > will be unmapped from the kernel direct map and they will be only mapped in > the page table of the owning mm. > > The secret memory remains accessible in the process context using uaccess > primitives, but it is not accessible using direct/linear map addresses. > > Functions in the follow_page()/get_user_page() family will refuse to return > a page that belongs to the secret memory area. > > A page that was a part of the secret memory area is cleared when it is > freed. > > The following example demonstrates creation of a secret mapping (error > handling is omitted): > > fd = memfd_secret(0); > ftruncate(fd, MAP_SIZE); > ptr = mmap(NULL, MAP_SIZE, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0); I do not see any access control or permission model for this feature. Is this feature generally safe to anybody? -- Michal Hocko SUSE Labs _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel