From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 39518C2B9F4 for ; Mon, 14 Jun 2021 21:13:32 +0000 (UTC) Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [216.205.24.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id CAF8F6128C for ; Mon, 14 Jun 2021 21:13:31 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org CAF8F6128C Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=tempfail smtp.mailfrom=linux-audit-bounces@redhat.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1623705210; h=from:from:sender:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:list-id:list-help: list-unsubscribe:list-subscribe:list-post; bh=nKiBvI9VfL69b/aHIbwa2yMICYzBF9dQKbUUk8ojykY=; b=FDacWaW3OMEbq5nFsoBjqI4borbfagliKWpTq4TmWGuBbx4EPxLzJaYhVp6FwDa3E8iNpg yAEigR0uoU7o7qaZv04ZqLRStUmcSLOOp1b6AZw8YZ0A81DSx7Ol+6LeeZ3jvwVtQfnpUz PF68tLbJINT/W7ig0ZXc6PaGlipARxM= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-515-ll3xtud5MnCx0p-1CDwOiw-1; Mon, 14 Jun 2021 17:13:29 -0400 X-MC-Unique: ll3xtud5MnCx0p-1CDwOiw-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 6B9BFC73A1; Mon, 14 Jun 2021 21:13:26 +0000 (UTC) Received: from colo-mx.corp.redhat.com (colo-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.21]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 838655D6DC; Mon, 14 Jun 2021 21:13:25 +0000 (UTC) Received: from lists01.pubmisc.prod.ext.phx2.redhat.com (lists01.pubmisc.prod.ext.phx2.redhat.com [10.5.19.33]) by colo-mx.corp.redhat.com (Postfix) with ESMTP id B74C74ED7A; Mon, 14 Jun 2021 21:13:24 +0000 (UTC) Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) by lists01.pubmisc.prod.ext.phx2.redhat.com (8.13.8/8.13.8) with ESMTP id 15ELDNK6017007 for ; Mon, 14 Jun 2021 17:13:23 -0400 Received: by smtp.corp.redhat.com (Postfix) id 7A1D060FC2; Mon, 14 Jun 2021 21:13:23 +0000 (UTC) Received: from x2.localnet (ovpn-117-28.rdu2.redhat.com [10.10.117.28]) by smtp.corp.redhat.com (Postfix) with ESMTP id 417AB60C4A; Mon, 14 Jun 2021 21:13:19 +0000 (UTC) From: Steve Grubb To: Casey Schaufler Subject: Re: Adding support for MAC_TASK_CONTEXTS and MAC_OBJ_CONTEXTS to userspace. Date: Mon, 14 Jun 2021 17:13:17 -0400 Message-ID: <7967755.NyiUUSuA9g@x2> Organization: Red Hat In-Reply-To: References: MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 X-loop: linux-audit@redhat.com Cc: "linux-audit@redhat.com" X-BeenThere: linux-audit@redhat.com X-Mailman-Version: 2.1.12 Precedence: junk List-Id: Linux Audit Discussion List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: linux-audit-bounces@redhat.com Errors-To: linux-audit-bounces@redhat.com X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=linux-audit-bounces@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Hello, On Monday, June 14, 2021 3:34:33 PM EDT Casey Schaufler wrote: > I'm looking at the audit userspace implications of adding two > new kernel audit records. AUDIT_MAC_TASK_CONTEXTS and > AUDIT_MAC_OBJ_CONTEXTS are used when there are multiple security > modules with a "security context" active on the system. This > design has been discussed here at length. The records will look > like: > > AUDIT_MAC_TASK_CONTEXTS > subj_=value > subj_=value > ... > > Looking at the audit user-space code I see several things > that have me concerned. The first is the use of WITH_APPARMOR. > Going forward what behavior would we want if subj_apparmor=something > shows up on a system that has not got WITH_APPARMOR defined? I think it should be ignored. > The code is inconsistent in that it does not use WITH_SELINUX, > but that's hardly a surprise given its origins. There is also no > WITH_SMACK, but that's unlikely to be an issue since Smack's use > of audit is very much like SELinux's. We can add those WITH_* if you like. > The question is what to > do about filtering when subj=foo is specified. I suggest that if > any of subj_selinux, subj_smack or subj_something is "foo", it is > a match. I think that's how we already treat things. There is a linked list for AVC's and we match on any of. > But the SELinux components of a label (level, user, ...) > are also available for filtering. If someone wrote a simple Bell & > LaPadula LSM filtering by some of those fields could be useful > there, too. > > I would like guidance on whether I ought to go the route of > more extensive use of WITH_APPARMOR (and WITH_SMACK, WITH_MUMBLE) > or take the path of greater generalization. Or, whether I should > treat each case individually and give it my best whack. To be honest, I have no idea how well the audit system works with any MAC system except SE Linux. I don't really know if its doing the right thing. Ausearch and report share a parser. It is time sensitive. I usually test it on 4 or 5 Gb of logs. We also have the ausearch-test program which can be used to test any changes to the parser. http://people.redhat.com/sgrubb/audit/ausearch-test-0.6.tar.gz Once that is squared away, there is the auparse library. It has a table that classifies a field name into what it is for interpretation purposes. You will find a #ifdef WITH_APPARMOR. I don't know if that table is complete or if it needs to be extended for any other MAC system. That then leads to the auparse normalizer. I don't know if we need to make any changes there. You can trigger its code with ausearch --format csv or -- format text. Also, we have some size limits in user space. How big can an event record be if the file is MAX_PATH name length and it has a space in its name or directory and each context is it's maximum size? We may need to think about how this might change the whole userspace ecosystem's size definition, MAX_AUDIT_MESSAGE_LENGTH, since this is part of the ABI. And the kernel also has AUDIT_MESSAGE_TEXT_MAX. What would you get with: # /usr/sbin/auditctl -m `perl -e 'print "A"x8880'` And last...what about auditctl? Is the syscall filter going to allow filtering on these other subject/object components? -Steve -- Linux-audit mailing list Linux-audit@redhat.com https://listman.redhat.com/mailman/listinfo/linux-audit