From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qk1-f197.google.com (mail-qk1-f197.google.com [209.85.222.197]) by kanga.kvack.org (Postfix) with ESMTP id 8E7F66B0003 for ; Fri, 19 Oct 2018 13:32:11 -0400 (EDT) Received: by mail-qk1-f197.google.com with SMTP id r77-v6so36628474qke.3 for ; Fri, 19 Oct 2018 10:32:11 -0700 (PDT) Received: from omr2.cc.vt.edu (omr2.cc.ipv6.vt.edu. [2607:b400:92:8400:0:33:fb76:806e]) by mx.google.com with ESMTPS id m185-v6si50065qkb.188.2018.10.19.10.32.10 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 19 Oct 2018 10:32:10 -0700 (PDT) Received: from mr1.cc.vt.edu (mr1.cc.ipv6.vt.edu [IPv6:2607:b400:92:8300:0:31:1732:8aa4]) by omr2.cc.vt.edu (8.14.4/8.14.4) with ESMTP id w9JHWAEd019508 for ; Fri, 19 Oct 2018 13:32:10 -0400 Received: from mail-qk1-f199.google.com (mail-qk1-f199.google.com [209.85.222.199]) by mr1.cc.vt.edu (8.14.7/8.14.7) with ESMTP id w9JHW5e0008437 for ; Fri, 19 Oct 2018 13:32:10 -0400 Received: by mail-qk1-f199.google.com with SMTP id y201-v6so36546447qka.1 for ; Fri, 19 Oct 2018 10:32:10 -0700 (PDT) From: valdis.kletnieks@vt.edu Subject: Re: [PATCH v3 1/2] mm: Add an F_SEAL_FUTURE_WRITE seal to memfd In-Reply-To: <20181018065908.254389-1-joel@joelfernandes.org> References: <20181018065908.254389-1-joel@joelfernandes.org> Mime-Version: 1.0 Content-Type: multipart/signed; boundary="==_Exmh_1539970322_3102P"; micalg=pgp-sha1; protocol="application/pgp-signature" Content-Transfer-Encoding: 7bit Date: Fri, 19 Oct 2018 13:32:02 -0400 Message-ID: <42922.1539970322@turing-police.cc.vt.edu> Sender: owner-linux-mm@kvack.org List-ID: To: "Joel Fernandes (Google)" Cc: linux-kernel@vger.kernel.org, kernel-team@android.com, jreck@google.com, john.stultz@linaro.org, tkjos@google.com, gregkh@linuxfoundation.org, hch@infradead.org, Al Viro , Andrew Morton , dancol@google.com, "J. Bruce Fields" , Jeff Layton , linux-fsdevel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-mm@kvack.org, marcandre.lureau@redhat.com, Mike Kravetz , minchan@kernel.org, Shuah Khan , Thomas Gleixner --==_Exmh_1539970322_3102P Content-Type: text/plain; charset=us-ascii On Wed, 17 Oct 2018 23:59:07 -0700, "Joel Fernandes (Google)" said: > This usecase cannot be implemented with the existing F_SEAL_WRITE seal. > To support the usecase, this patch adds a new F_SEAL_FUTURE_WRITE seal > which prevents any future mmap and write syscalls from succeeding while > keeping the existing mmap active. The following program shows the seal > working in action: What is supposed to happen if some other process has an already existing R/W mmap of the region? (For that matter, the test program doesn't seem to actually test that the existing mmap region remains writable?) --==_Exmh_1539970322_3102P Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Comment: Exmh version 2.8.0 04/21/2017 iQEVAwUBW8oVEo0DS38y7CIcAQLWJQf8DQ1cQowO3bfaWQWZBNXxbcCeCMPYgp1w 3XFonoT+hSpd45gHazrRRXmfR3BJ0wb9wZHsE0CCCpmuXlNnH2WOmKB7/ly/5lb8 RQhT8ahp8/OzRpRnfDlLQEIbAY/5kT4XGRf1wjVBnonPYY8aXjSj44dyBIaPh8XZ GJLYEL6++rWifApraHDHgBbMQCEn7HMXnvoHtIcV3/ihRj+bo7H74Cr8S7e6dPCP sLtruVLu00SYYHkTI6l0rSAZiMiYJnVyuk3bju4jTMqX7KayRCmzS9X+65F5jb/M qJhZ/DLjV/n3/DqK9u2z5tOsiN4scyW1ThQpK+tjXj0SC+9a0VoAoQ== =fFpS -----END PGP SIGNATURE----- --==_Exmh_1539970322_3102P--