From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751762AbdCADoN (ORCPT ); Tue, 28 Feb 2017 22:44:13 -0500 Received: from mx1.redhat.com ([209.132.183.28]:35842 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751655AbdCADoL (ORCPT ); Tue, 28 Feb 2017 22:44:11 -0500 Date: Tue, 28 Feb 2017 22:37:04 -0500 From: Richard Guy Briggs To: Linux-Audit Mailing List , LKML Cc: Steven Rostedt , Ingo Molnar , Greg Kroah-Hartman , Al Viro , Eric Paris , Paul Moore , Steve Grubb Subject: Re: Hundreds of null PATH records for *init_module syscall audit logs Message-ID: <20170301033704.GU18258@madcap2.tricolour.ca> References: <20170301031549.GT18258@madcap2.tricolour.ca> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170301031549.GT18258@madcap2.tricolour.ca> User-Agent: Mutt/1.5.21 (2010-09-15) X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.38]); Wed, 01 Mar 2017 03:37:11 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Sorry, I forgot to include Cc: in this cover letter for context to the 4 alt patches. On 2017-02-28 22:15, Richard Guy Briggs wrote: > The background to this is: > https://github.com/linux-audit/audit-kernel/issues/8 > > In short, audit SYSCALL records for *init_module were occasionally > accompanied by hundreds to thousands of null PATH records. > > I chatted with Al Viro and Eric Paris about this Friday afternoon and > they seemed to vaguely recall this issue and didn't have any solid > recommendations as to what was the right thing to do (other than the > same suggestion from both that I won't print here). > > It was reproducible on a number of vintages of distributions with > default kernels, but triggering on very few of the many modules loaded > at boot time. It was reproduced with fs-nfs4 and nfsv4 modules on > tracefs, but there are reports of it also happening with debugfs. It > was triggering only in __audit_inode_child with a parent that was not > found in the task context's audit names_list. > > I have four potential solutions listed in my order of preference and I'd > like to get some feedback about which one would be the most acceptable. > > 1 - In __audit_inode_child, return immedialy upon detecting TRACEFS and > DEBUGFS (and potentially other filesystems identified, via s_magic). > > 2 - In __audit_inode_child, return after not finding the parent in that > task context's audit names_list. > > 3 - In __audit_inode_child, mark the parent and its child as "hidden" > when the parent isn't found in that task context's audit names_list. > This will still result in an "items=" count that does not match the > number of accompanying PATH records for that SYSCALL record, which > may upset userspace tools but would still indicate suppressed > records. > > 4 - In __audit_inode_child, when the parent isn't found, store the > child's dentry in the child's (new or not) audit_names structure > (properly refcounted with dget) and store the parent's dentry in its > newly created audit_names structure (via dget_parent), then if the > name isn't available at PATH record generation time, use that stored > value (with dentry_path_raw and released with dput) > > Is there another more elegant solution that I've missed that catches > things before they get anywhere near audit_inode_child (called from > tracefs' notifiers)? > > I'll thread onto this message tested patches for all four solutions. > > > - RGB > > -- > Richard Guy Briggs > Kernel Security Engineering, Base Operating Systems, Red Hat > Remote, Ottawa, Canada > Voice: +1.647.777.2635, Internal: (81) 32635 - RGB -- Richard Guy Briggs Kernel Security Engineering, Base Operating Systems, Red Hat Remote, Ottawa, Canada Voice: +1.647.777.2635, Internal: (81) 32635