From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mimi Zohar Subject: Re: [PATCH v2 0/3] initramfs: add support for xattrs in the initial ram disk Date: Sun, 12 May 2019 20:02:30 -0400 Message-ID: <1557705750.10635.264.camel@linux.ibm.com> References: <20190512153105.GA25254@light.dominikbrodowski.net> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8bit Return-path: In-Reply-To: <20190512153105.GA25254@light.dominikbrodowski.net> Sender: linux-kernel-owner@vger.kernel.org To: Dominik Brodowski , hpa@zytor.com Cc: Roberto Sassu , viro@zeniv.linux.org.uk, 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, arnd@arndb.de, rob@landley.net, james.w.mcmechan@gmail.com List-Id: linux-api@vger.kernel.org On Sun, 2019-05-12 at 17:31 +0200, Dominik Brodowski wrote: > On Sun, May 12, 2019 at 08:52:47AM -0400, Mimi Zohar wrote: > > It's too late. The /init itself should be signed and verified. > > Could you elaborate a bit more about the threat model, and why deferring > this to the initramfs is too late? The IMA policy defines a number of different methods of identifying which files to measure, appraise, audit.[1]  Without xattrs, the granularity of the policy rules is severely limited.  Without xattrs, a filesystem is either in policy, or not. With an IMA policy rule requiring rootfs (tmpfs) files to be verified, then /init needs to be properly labeled, otherwise /init will fail to execute. Mimi [1] Documentation/ABI/testing/ima_policy