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[2001:468:c80:2103:f21f:afff:fe0c:8ada]) by smtp.gmail.com with ESMTPSA id w39-v6sm17659595qtc.84.2018.10.19.10.32.02 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Fri, 19 Oct 2018 10:32:03 -0700 (PDT) From: valdis.kletnieks@vt.edu X-Google-Original-From: Valdis.Kletnieks@vt.edu X-Mailer: exmh version 2.8.0 04/21/2017 with nmh-1.7+dev 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 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: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --==_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--