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[209.85.217.46]) by smtp.gmail.com with ESMTPSA id v22sm4469337vkv.35.2019.04.23.15.19.27 for (version=TLS1_3 cipher=AEAD-AES128-GCM-SHA256 bits=128/128); Tue, 23 Apr 2019 15:19:27 -0700 (PDT) Received: by mail-vs1-f46.google.com with SMTP id f15so9228547vsk.9 for ; Tue, 23 Apr 2019 15:19:27 -0700 (PDT) X-Received: by 2002:a67:f849:: with SMTP id b9mr14894109vsp.188.1556057966875; Tue, 23 Apr 2019 15:19:26 -0700 (PDT) MIME-Version: 1.0 References: <20190319030722.12441-1-peterx@redhat.com> <20190319030722.12441-2-peterx@redhat.com> <20190319110236.b6169d6b469a587a852c7e09@linux-foundation.org> In-Reply-To: <20190319110236.b6169d6b469a587a852c7e09@linux-foundation.org> From: Kees Cook Date: Tue, 23 Apr 2019 15:19:15 -0700 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH v2 1/1] userfaultfd/sysctl: add vm.unprivileged_userfaultfd To: Andrew Morton Cc: Peter Xu , LKML , Paolo Bonzini , Hugh Dickins , Luis Chamberlain , Maxime Coquelin , Maya Gokhale , Jerome Glisse , Pavel Emelyanov , Johannes Weiner , Martin Cracauer , Denis Plotnikov , Linux-MM , Marty McFadden , Mike Kravetz , Andrea Arcangeli , Mike Rapoport , Kees Cook , Mel Gorman , "Kirill A . Shutemov" , Linux API , "linux-fsdevel@vger.kernel.org" , "Dr . David Alan Gilbert" Content-Type: text/plain; charset="UTF-8" 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: On Tue, Mar 19, 2019 at 11:02 AM Andrew Morton wrote: > > On Tue, 19 Mar 2019 11:07:22 +0800 Peter Xu wrote: > > > Add a global sysctl knob "vm.unprivileged_userfaultfd" to control > > whether userfaultfd is allowed by unprivileged users. When this is > > set to zero, only privileged users (root user, or users with the > > CAP_SYS_PTRACE capability) will be able to use the userfaultfd > > syscalls. > > Please send along a full description of why you believe Linux needs > this feature, for me to add to the changelog. What is the benefit to > our users? How will it be used? > > etcetera. As it was presented I'm seeing no justification for adding > the patch! Was there a v3 of this patch? I'd still really like to have this knob added. :) Thanks! -- Kees Cook