From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from omta002.cacentral1.a.cloudfilter.net (omta002.cacentral1.a.cloudfilter.net [3.97.99.33]) by sourceware.org (Postfix) with ESMTPS id B7A053858D28 for ; Sun, 17 Oct 2021 17:21:40 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org B7A053858D28 Authentication-Results: sourceware.org; dmarc=none (p=none dis=none) header.from=SystematicSw.ab.ca Authentication-Results: sourceware.org; spf=none smtp.mailfrom=systematicsw.ab.ca Received: from shw-obgw-4004a.ext.cloudfilter.net ([10.228.9.227]) by cmsmtp with ESMTP id c6DimkAQSps7Pc9qtmEZRf; Sun, 17 Oct 2021 17:21:39 +0000 Received: from [192.168.1.105] ([68.147.0.90]) by cmsmtp with ESMTP id c9qtm2PFua8XRc9qtmkdhy; Sun, 17 Oct 2021 17:21:39 +0000 X-Authority-Analysis: v=2.4 cv=Ov8sdwzt c=1 sm=1 tr=0 ts=616c5ba3 a=T+ovY1NZ+FAi/xYICV7Bgg==:117 a=T+ovY1NZ+FAi/xYICV7Bgg==:17 a=IkcTkHD0fZMA:10 a=NvJIefd1AAAA:8 a=yMhMjlubAAAA:8 a=uYT-Tk0qkVT609LjNaIA:9 a=QEXdDO2ut3YA:10 a=ogbyGQH7ugUA:10 a=zGUkOKmOs2wA:10 a=Z11pERy037KCMjAKJWwP:22 Reply-To: cygwin@cygwin.com To: cygwin@cygwin.com From: Brian Inglis Organization: Systematic Software Subject: Windows October Update Patch Could Affect Symlinks Message-ID: Date: Sun, 17 Oct 2021 11:21:39 -0600 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.14.0 MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-CA Content-Transfer-Encoding: 8bit X-CMAE-Envelope: MS4xfBt+afXLDn4gCX8eC9InPWzA/I5molwxI4HA/XVoD4m+gzcdgBXvau+Nf0Yq3Pz3dqEceUH7yUyzobBnia80p55fC3sVOuPqVKcPauJVcU57QYW7HSQS 4KdFKXCDFIsG7VIKYLhkicKQzfJgW0MecJQ+X2DEF7FcrZnLsD3j36OgFrsKjm4HWHgNhQ2oRLBWpYRgVQTl6FBmLHFlqmcOdnQ= X-Spam-Status: No, score=-1159.3 required=5.0 tests=BAYES_00, INDUSTRIAL_SUBJECT, KAM_DMARC_STATUS, KAM_LAZY_DOMAIN_SECURITY, RCVD_IN_BARRACUDACENTRAL, RCVD_IN_DNSWL_NONE, RCVD_IN_MSPIKE_H3, RCVD_IN_MSPIKE_WL, SPF_HELO_NONE, SPF_NONE, TXREP autolearn=no autolearn_force=no version=3.4.4 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on server2.sourceware.org X-BeenThere: cygwin@cygwin.com X-Mailman-Version: 2.1.29 Precedence: list List-Id: General Cygwin discussions and problem reports List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 17 Oct 2021 17:21:42 -0000 While checking Windows October update patches found a vague reference to a new Windows update patch affecting symlinks in the article: https://www.computerworld.com/article/3637013/four-zero-day-exploits-add-urgency-to-octobers-patch-tuesday.html "On the topic of lesser-used Windows features, the Microsoft NTFS file system was updated to include a fix for symbolic links (helpful with UNIX migrations). If you are in the middle of a large UNIX migration, you may want to pause things a little and test out some large (and parallel) file transfers before deploying this update." Could not find anything definite about this patch or its effects or whether it will create any issues. So this is just a heads up about potential issues implied by the article. If anyone can find the actual patch and any docs documenting potential changes or issues that may help. The article's links to overview and generic articles on NTFS and symlinks did not help: https://docs.microsoft.com/en-us/windows/security/threat-protection/security-policy-settings/create-symbolic-links#security-considerations pointing to existing: https://docs.microsoft.com/en-us/windows-server/administration/windows-commands/fsutil-behavior On my system, that shows: Elevated > fsutil behavior set symlinkevaluation /? | grep -E "sym|link" ... symlinkEvaluation {L2L|L2R|R2R|R2L}:{0|1} [...] ... Sample SymlinkEvaluation command: "fsutil behavior set symlinkEvaluation L2L:1 L2R:0" - Will enable local to local symbolic links and disable local to remote symbolic links. It will not change the state of remote to remote links or remote to local links. - This operation takes effect immediately (no reboot required) ... Elevated > fsutil behavior query symlinkevaluation Local to local symbolic links are enabled. Local to remote symbolic links are enabled. Remote to local symbolic links are disabled. Remote to remote symbolic links are disabled. ... -- Take care. Thanks, Brian Inglis, Calgary, Alberta, Canada This email may be disturbing to some readers as it contains too much technical detail. Reader discretion is advised. [Data in binary units and prefixes, physical quantities in SI.]