From mboxrd@z Thu Jan 1 00:00:00 1970 From: Roberto Sassu Subject: Re: [PATCH v2 0/3] initramfs: add support for xattrs in the initial ram disk Date: Fri, 10 May 2019 08:56:18 +0200 Message-ID: References: <20190509112420.15671-1-roberto.sassu@huawei.com> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8"; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org To: Rob Landley , viro@zeniv.linux.org.uk Cc: linux-security-module@vger.kernel.org, linux-integrity@vger.kernel.org, initramfs@vger.kernel.org, linux-api@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, zohar@linux.vnet.ibm.com, silviu.vlasceanu@huawei.com, dmitry.kasatkin@huawei.com, takondra@cisco.com, kamensky@cisco.com, hpa@zytor.com, arnd@arndb.de, james.w.mcmechan@gmail.com List-Id: linux-api@vger.kernel.org On 5/9/2019 8:34 PM, Rob Landley wrote: > On 5/9/19 6:24 AM, Roberto Sassu wrote: >> This patch set aims at solving the following use case: appraise files from >> the initial ram disk. To do that, IMA checks the signature/hash from the >> security.ima xattr. Unfortunately, this use case cannot be implemented >> currently, as the CPIO format does not support xattrs. >> >> This proposal consists in marshaling pathnames and xattrs in a file called >> .xattr-list. They are unmarshaled by the CPIO parser after all files have >> been extracted. > > So it's in-band signalling that has a higher peak memory requirement. This can be modified. Now I allocate the memory necessary for the path and all xattrs of a file (max: .xattr-list size - 10 bytes). I could process each xattr individually (max: 255 + 1 + 65536 bytes). >> The difference with another proposal >> (https://lore.kernel.org/patchwork/cover/888071/) is that xattrs can be >> included in an image without changing the image format, as opposed to >> defining a new one. As seen from the discussion, if a new format has to be >> defined, it should fix the issues of the existing format, which requires >> more time. > > So you've explicitly chosen _not_ to address Y2038 while you're there. Can you be more specific? Thanks Roberto > Rob > -- HUAWEI TECHNOLOGIES Duesseldorf GmbH, HRB 56063 Managing Director: Bo PENG, Jian LI, Yanli SHI