From owner-freebsd-security@freebsd.org Tue Apr 21 22:50:32 2020 Return-Path: Delivered-To: freebsd-security@mailman.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.nyi.freebsd.org (Postfix) with ESMTP id 01FA02BD158 for ; Tue, 21 Apr 2020 22:50:32 +0000 (UTC) (envelope-from eugen@grosbein.net) Received: from hz.grosbein.net (hz.grosbein.net [IPv6:2a01:4f8:c2c:26d8::2]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client CN "hz.grosbein.net", Issuer "hz.grosbein.net" (not verified)) by mx1.freebsd.org (Postfix) with ESMTPS id 496JgV1r67z4KmP; Tue, 21 Apr 2020 22:50:29 +0000 (UTC) (envelope-from eugen@grosbein.net) Received: from eg.sd.rdtc.ru (eg.sd.rdtc.ru [IPv6:2a03:3100:c:13:0:0:0:5]) by hz.grosbein.net (8.15.2/8.15.2) with ESMTPS id 03LMoJKr028841 (version=TLSv1.2 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Tue, 21 Apr 2020 22:50:22 GMT (envelope-from eugen@grosbein.net) X-Envelope-From: eugen@grosbein.net X-Envelope-To: emaste@freebsd.org Received: from [10.58.0.10] (dadvw [10.58.0.10]) by eg.sd.rdtc.ru (8.15.2/8.15.2) with ESMTPS id 03LMoIoh073831 (version=TLSv1.2 cipher=DHE-RSA-AES128-SHA bits=128 verify=NOT); Wed, 22 Apr 2020 05:50:18 +0700 (+07) (envelope-from eugen@grosbein.net) Subject: Re: [FreeBSD-Announce] FreeBSD Security Advisory FreeBSD-SA-20:10.ipfw To: Ed Maste , "Andrey V. Elsukov" References: <20200421165514.C676C1CB78@freefall.freebsd.org> <54bfc0f6-be4c-349d-df87-8ba507803a04@grosbein.net> Cc: freebsd-security@freebsd.org From: Eugene Grosbein Message-ID: Date: Wed, 22 Apr 2020 05:50:12 +0700 User-Agent: Mozilla/5.0 (Windows NT 6.3; WOW64; rv:45.0) Gecko/20100101 Thunderbird/45.8.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit X-Spam-Status: No, score=0.3 required=5.0 tests=BAYES_00,LOCAL_FROM, SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.2 X-Spam-Report: * -2.3 BAYES_00 BODY: Bayes spam probability is 0 to 1% * [score: 0.0000] * 0.0 SPF_HELO_NONE SPF: HELO does not publish an SPF Record * -0.0 SPF_PASS SPF: sender matches SPF record * 2.6 LOCAL_FROM From my domains X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on hz.grosbein.net X-Rspamd-Queue-Id: 496JgV1r67z4KmP X-Spamd-Bar: --- Authentication-Results: mx1.freebsd.org; dkim=none; dmarc=none; spf=permerror (mx1.freebsd.org: domain of eugen@grosbein.net uses mechanism not recognized by this client) smtp.mailfrom=eugen@grosbein.net X-Spamd-Result: default: False [-3.99 / 15.00]; ARC_NA(0.00)[]; NEURAL_HAM_MEDIUM(-1.00)[-1.000,0]; FROM_HAS_DN(0.00)[]; RCPT_COUNT_THREE(0.00)[3]; TO_DN_SOME(0.00)[]; TO_MATCH_ENVRCPT_ALL(0.00)[]; MIME_GOOD(-0.10)[text/plain]; DMARC_NA(0.00)[grosbein.net]; NEURAL_HAM_LONG(-1.00)[-1.000,0]; RCVD_COUNT_THREE(0.00)[3]; IP_SCORE(-1.89)[ip: (-5.23), ipnet: 2a01:4f8::/29(-2.64), asn: 24940(-1.54), country: DE(-0.02)]; R_SPF_PERMFAIL(0.00)[]; FROM_EQ_ENVFROM(0.00)[]; R_DKIM_NA(0.00)[]; MIME_TRACE(0.00)[0:+]; ASN(0.00)[asn:24940, ipnet:2a01:4f8::/29, country:DE]; MID_RHS_MATCH_FROM(0.00)[]; RCVD_TLS_ALL(0.00)[] X-BeenThere: freebsd-security@freebsd.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: "Security issues \[members-only posting\]" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 21 Apr 2020 22:50:32 -0000 22.04.2020 5:15, Ed Maste wrote: >>> IV. Workaround >>> >>> No workaround is available. Systems not using the ipfw firewall are >>> not vulnerable. >> >> This is not true. The problem affects only seldom used rules matching TCP packets >> by list of TCP options (rules with "tcpoptions" keyword) and/or by TCP MSS size >> (rules with matching "tcpmss" keyword, don't mix with "tcp-setmss" action keyword). > > I believe this is correct; what about this statement: > > No workaround is available. Systems not using the ipfw firewall, and > systems that use the ipfw firewall but without any rules using "tcpoptions" > or "tcpmss" keywords, are not affected. Isn't removing rules with "tcpoptions/tcpmss" considered as work-around? Such rules may be replaced with "ipfw netgraph" rules and processing TCP options with NETGRAPH node ng_bpf(4). Seems as work-around to me.