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[73.120.18.128]) by smtp.gmail.com with ESMTPSA id q11sm3765149ywl.99.2019.02.12.15.00.46 (version=TLS1_3 cipher=AEAD-AES128-GCM-SHA256 bits=128/128); Tue, 12 Feb 2019 15:00:47 -0800 (PST) To: Al Viro Cc: "open list:FILESYSTEMS (VFS and infrastructure)" , open list References: <20190212145450.2200-1-demiobenour@gmail.com> <20190212145450.2200-4-demiobenour@gmail.com> <20190212203809.GK2217@ZenIV.linux.org.uk> From: "Demi M. Obenour" Openpgp: preference=signencrypt Subject: Re: [PATCH 4/4] Return -EINVAL if userspace passes bogus flags to open() Message-ID: Date: Tue, 12 Feb 2019 18:00:44 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.5.0 MIME-Version: 1.0 In-Reply-To: <20190212203809.GK2217@ZenIV.linux.org.uk> Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="6z3eDRomUoICfopK7sXJ71tceJ9PE28t5" Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --6z3eDRomUoICfopK7sXJ71tceJ9PE28t5 Content-Type: multipart/mixed; boundary="fRv3Va28yBlsAQzFnvmZizGA0RsArkMwY"; protected-headers="v1" From: "Demi M. Obenour" To: Al Viro Cc: "open list:FILESYSTEMS (VFS and infrastructure)" , open list Message-ID: Subject: Re: [PATCH 4/4] Return -EINVAL if userspace passes bogus flags to open() References: <20190212145450.2200-1-demiobenour@gmail.com> <20190212145450.2200-4-demiobenour@gmail.com> <20190212203809.GK2217@ZenIV.linux.org.uk> In-Reply-To: <20190212203809.GK2217@ZenIV.linux.org.uk> --fRv3Va28yBlsAQzFnvmZizGA0RsArkMwY Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: quoted-printable On 2/12/19 3:38 PM, Al Viro wrote: > On Tue, Feb 12, 2019 at 09:54:47AM -0500, demiobenour@gmail.com wrote: >> From: "Demi M. Obenour" >> >> While testing the O_PATHSTATIC patch, I discovered that Linux does not= >> return any error if an invalid flag is passed to open(2). This preven= ts >> adding new flags without a (minor) risk of breaking userspace. >> Therefore, add a check for invalid flags, and return -EINVAL if any ar= e >> found. >=20 > ... which would qualtify as userland ABI breakage all by itself. >=20 I suspect that very few (if any) programs pass invalid flags to open(). Additionally, O_DIRECT was added in Linux 2.4, even though it had previously been ignored. If someone knows of a real program that does, I can instead create an open2() syscall, but I would prefer to avoid that= =2E --fRv3Va28yBlsAQzFnvmZizGA0RsArkMwY-- --6z3eDRomUoICfopK7sXJ71tceJ9PE28t5 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAEBCAAdFiEEdodNnxM2uiJZBxxxsoi1X/+cIsEFAlxjUBwACgkQsoi1X/+c IsGozQ//SmIGyfpXyUpUQW56wYTui24CRQ1SM7FaKj5E/yMWzM1LTzJQvlnsN7mc i6TGPkYWHoxvHDzEositaV6WJ7HIa/DFo1fwZNoRo/HpIN1fq8TE4aAgP41Tur1Z DhHI75Fo7Q6fEaiSSCI0Ce2QmP35LDC+TlvvODDLdoRLw79zWD7LtZWi0NJOrzBe 9otEA8BOf9W0dpgOQgi6Am73y8JQGhoae057koiGaYOXFISI9d1Wb2zQM4np+YZA aUKoaaIO6ClB4n2X48V252YYMi4RqJvUu5MW7ngVY1JFnmguIQOLlQSP6rsMOtCf U+2h8YpJOzi+XKFL65ZFSVE6T2H22xT6zRq73fWUUZ/PJ0qxKTN298OAYHzqSU7d 1PI6bLnsy+IAY5vobuqCmFhBJtqfW9o17b/BB7C5xC5dB8ksenPho23JH/uLiuIg fcoHGNaYnTVJ2HnwOdFhz52TUOKs79llMSsAPzq+ZnceNb8XqQYdqPtBRKrwjrak iFfzDGpYrGJfxxV1WDbJ8gTxpixM3l+UcxfWbaJXLODoDvUMRJJO28ECkMAMpD4C +5nnxcplO8UeyS4Jt9O7czWg0Te2QvEcR4p9OxUQ4gb5UM0GMYOyH3miPO/3WlUa ycIt2CH5nkWixQ9f98py1GVckYjsjQoSQF4f5QS4NYlpRXlOj44= =LveP -----END PGP SIGNATURE----- --6z3eDRomUoICfopK7sXJ71tceJ9PE28t5--