From owner-freebsd-current@freebsd.org Tue Dec 29 01:19:43 2020 Return-Path: Delivered-To: freebsd-current@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 13EFC4C9142 for ; Tue, 29 Dec 2020 01:19:43 +0000 (UTC) (envelope-from jmg@gold.funkthat.com) Received: from gold.funkthat.com (gate2.funkthat.com [208.87.223.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client CN "gate2.funkthat.com", Issuer "R3" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 4D4c5p0R66z510X; Tue, 29 Dec 2020 01:19:41 +0000 (UTC) (envelope-from jmg@gold.funkthat.com) Received: from gold.funkthat.com (localhost [127.0.0.1]) by gold.funkthat.com (8.15.2/8.15.2) with ESMTPS id 0BT1JdPp053569 (version=TLSv1.2 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=NO); Mon, 28 Dec 2020 17:19:39 -0800 (PST) (envelope-from jmg@gold.funkthat.com) Received: (from jmg@localhost) by gold.funkthat.com (8.15.2/8.15.2/Submit) id 0BT1JdUA053568; Mon, 28 Dec 2020 17:19:39 -0800 (PST) (envelope-from jmg) Date: Mon, 28 Dec 2020 17:19:39 -0800 From: John-Mark Gurney To: Brooks Davis , Thomas Mueller , freebsd-current@freebsd.org Subject: Re: HEADS UP: FreeBSD src repo transitioning to git this weekend Message-ID: <20201229011939.GU31099@funkthat.com> Mail-Followup-To: Brooks Davis , Thomas Mueller , freebsd-current@freebsd.org References: <31ab8015-a0c4-af77-0ead-a17da0f88f1d@freebsd.org> <5fdc0b90.1c69fb81.866eb.8c29SMTPIN_ADDED_MISSING@mx.google.com> <20201218175241.GA72552@spindle.one-eyed-alien.net> <20201218182820.1P0tK%steffen@sdaoden.eu> <20201223023242.GG31099@funkthat.com> <20201223162417.v7Ce6%steffen@sdaoden.eu> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201223162417.v7Ce6%steffen@sdaoden.eu> X-Operating-System: FreeBSD 11.3-STABLE amd64 X-PGP-Fingerprint: D87A 235F FB71 1F3F 55B7 ED9B D5FF 5A51 C0AC 3D65 X-Files: The truth is out there X-URL: https://www.funkthat.com/ X-Resume: https://www.funkthat.com/~jmg/resume.html X-TipJar: bitcoin:13Qmb6AeTgQecazTWph4XasEsP7nGRbAPE X-to-the-FBI-CIA-and-NSA: HI! HOW YA DOIN? can i haz chizburger? User-Agent: Mutt/1.6.1 (2016-04-27) X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.4.3 (gold.funkthat.com [127.0.0.1]); Mon, 28 Dec 2020 17:19:39 -0800 (PST) X-Rspamd-Queue-Id: 4D4c5p0R66z510X X-Spamd-Bar: / X-Spamd-Result: default: False [0.20 / 15.00]; RCVD_TLS_ALL(0.00)[]; ARC_NA(0.00)[]; FREEFALL_USER(0.00)[jmg]; FROM_HAS_DN(0.00)[]; RCPT_COUNT_THREE(0.00)[3]; TO_DN_SOME(0.00)[]; MID_RHS_MATCH_FROM(0.00)[]; MIME_GOOD(-0.10)[text/plain]; DMARC_NA(0.00)[funkthat.com]; RBL_DBL_DONT_QUERY_IPS(0.00)[208.87.223.18:from]; AUTH_NA(1.00)[]; NEURAL_SPAM_SHORT(1.00)[1.000]; SPAMHAUS_ZRD(0.00)[208.87.223.18:from:127.0.2.255]; TO_MATCH_ENVRCPT_SOME(0.00)[]; NEURAL_HAM_LONG(-1.00)[-1.000]; NEURAL_HAM_MEDIUM(-1.00)[-1.000]; R_SPF_NA(0.00)[no SPF record]; FREEMAIL_TO(0.00)[freebsd.org,twc.com]; FORGED_SENDER(0.30)[jmg@funkthat.com,jmg@gold.funkthat.com]; R_DKIM_NA(0.00)[]; MIME_TRACE(0.00)[0:+]; ASN(0.00)[asn:32354, ipnet:208.87.216.0/21, country:US]; FROM_NEQ_ENVFROM(0.00)[jmg@funkthat.com,jmg@gold.funkthat.com]; MAILMAN_DEST(0.00)[freebsd-current]; RCVD_COUNT_TWO(0.00)[2] X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 29 Dec 2020 01:19:43 -0000 Steffen Nurpmeso wrote this message on Wed, Dec 23, 2020 at 17:24 +0100: > |Then there's also the point that the repo is (looks like it) using > |SHA-1 hashes, which are effectively broken, so depending upon them > |to validate the tree is questionable anyways. > > git uses the hardened SHA-1 for sure, which is, as far as i know, > at least safe against the known attack. > I .. have not tracked this, but i think upgrading to SHA-256 is > possible, once this will become standard. Just even more > metadata, then. I have not looked into this, still in progress. A new attack came out earlier this year: https://eprint.iacr.org/2020/014.pdf >From the paper: > In particular, chosen-prefix collisions can break signature schemes and > handshake security in secure channel protocols (TLS, SSH), if generated > extremely quickly. The previous attack in 2017 did not break SHA-1 enough to render it's use by git vulnerable, but the writing was on the wall for SHA-1... I believe this new attack makes git's use a SHA-1 vulnerable... The type/length prefix that prevented the previous attacks from working is not effective against the new attack... Also, the cost of the attack is not great ($45k), considering the recent SolarWinds supply chain attack, being able to smuggle a modified file into a git repo, say an OS's build server, such that the tools don't know the tree is modified is a real problem... -- John-Mark Gurney Voice: +1 415 225 5579 "All that I will do, has been done, All that I have, has not."