From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=18.9.28.11 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1792693719; b=tiqv8H0n6Bsr1WWbJxhbiO22FBJrMEYcppkTWhON+eWScbhnFBz5d4wG8LC+nF6f8NGJ npKSJWd64k5sUVYcXGU0+VfjZWSIcBGSCdhGx8j7DL/xzNBu9PTpIOWcqar1iEikhZopz N3dvNVDcmO8Zi9jjaiNyzgalesumkkBhPL0Dgi2fkKwGlEhWKK8xHtESYOn8k8ocC+XGe IWVQfG5VR1Kqjev/fKdCNfuE6U1O68IvmvS+bWOjWNDrHlNcWwYdBEYNHPaF6ZgDixQal 6DIfkdmB14DjXPnyF3/82AKSDLsHhC5m46FUAJEqlyfpwdNupNCCGChBXF4IEBzhc/Q== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1792693719; h=DMARC-Filter:Received:DKIM-Signature:Received:Date:From:To:Cc: Subject:Message-ID:References:MIME-Version:Content-Type: Content-Disposition:In-Reply-To; bh=JYh+FSmeD5zBdSGmLXfoWsuKx9ehvUO73Rr6qnSc3X8=; b=4CBlD+tTncTb+yQUBgJuqdL27f30idYCUfx0dWUNui9OvpJWoDq/vMCh37C4FIFUvYdF 86a9wB5jWHfOBa5AArVct8fS86lJYlevzrjmc4AKqlmLCgq5OxST/7HBGb2WFpAM6Hkzl Vdafd+rDvGAVvhGdrnQFTSmnF1I+9sB0DyUrKR7+XJrTgPVfd26Lxm41KO3Xsw3bt5wOa u9hVOKUAp9x0v5/WGG5W5VQaFtTYPnZkCLoNF2G51QcbKYHo0RF5NMSQozA1crvEeTVXd wBUuI0/bI8Tb1nWUBvouBJjvTUVVKz6BcsmMqoV5wMCylQuV4M9wBVmmVs7cw7nfTRA== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass header.from=mit.edu; spf=pass smtp.mailfrom=mit.edu; dkim=pass header.d=mit.edu header.i=@mit.edu header.a=rsa-sha256 header.s=outgoing header.b=FB4rIzmo; arc=none smtp.remote-ip=18.9.28.11 Received: from outgoing.mit.edu (outgoing-auth-1.mit.edu [18.9.28.11]) (using TLSv1.2 with cipher ECDHE-ECDSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 37F5F606A326 for ; Thu, 22 Oct 2026 18:28:39 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org 37F5F606A326 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=mit.edu Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=mit.edu Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=mit.edu header.i=@mit.edu header.a=rsa-sha256 header.s=outgoing header.b=FB4rIzmo Received: from macsyma.thunk.org (pool-108-26-156-23.bstnma.fios.verizon.net [108.26.156.23]) (authenticated bits=0) (User authenticated as tytso@ATHENA.MIT.EDU) by outgoing.mit.edu (8.14.7/8.12.4) with ESMTP id 69MIRtlq008340 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Thu, 22 Oct 2026 14:27:56 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=mit.edu; s=outgoing; t=1792693680; bh=JYh+FSmeD5zBdSGmLXfoWsuKx9ehvUO73Rr6qnSc3X8=; h=Date:From:Subject:Message-ID:MIME-Version:Content-Type; b=FB4rIzmodCuc/ai76PzcPn8NKTCLCBgJQn5lG4OsNurD082LpzxvtWFDvX0WpozMi G5Wxrp5EKZivFppsyR/34R27Liveb8SHZHVPaUoS8ZK0SZqi5QIowbJZ3A3OxbM4VC T6wusZBLcMx4TA37NCtnpi9VcygARe/ydMqEQL+dUU2EOTWaGTS6Vg7HOcXefp/15T d7nP4c/UgU10vdDcWJP9aCfO9onPi6Wq2o/TdsUsdoFN9dfgwzIj5Cp6zqZxHaVWNY x9vDg8JooiFE5P2IxXk6tkIe6BLRPcasmFTfgbGaiWHz4u1SVqCZ6O7DWx0DCQCJGP /VtU8vRIAggOg== Received: by macsyma.thunk.org (Postfix, from userid 15806) id 96FCB22114B9; Thu, 22 Oct 2026 14:26:55 -0400 (EDT) Date: Thu, 22 Oct 2026 14:26:55 -0400 From: "Theodore Tso" To: Casey Schaufler Cc: Jan Koester , Christian Brauner , Alexander Viro , "Serge E. Hallyn" , Jan Kara , Paul Moore , Arnd Bergmann , linux-fsdevel@vger.kernel.org, linux-api@vger.kernel.org, linux-security-module@vger.kernel.org, linux-arch@vger.kernel.org, linux-ext4@vger.kernel.org, linux-nfs@vger.kernel.org, linux-cifs@vger.kernel.org, netdev@vger.kernel.org, audit@vger.kernel.org, keyrings@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [RFC PATCH v2 00/41] UUID and GUID user and group ids (*_r system calls) Message-ID: References: <018ca365-ce9b-424c-b600-bd9c8aefc9a1@schaufler-ca.com> X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <018ca365-ce9b-424c-b600-bd9c8aefc9a1@schaufler-ca.com> On Thu, Oct 22, 2026 at 10:00:16AM -0500, Casey Schaufler wrote: > > I can't see this being acceptable for a variety of reasons, including > but not limited to performance and configuration complexity. It's a > general solution for a special case or two, and the impact is significant. Yeah. I agree it's a non-starter. For one thing, it requires replacing every single system call which uses a 32-bit uid or gid --- either as an input parameter, a return value, or in a structure, such as, "struct stat". It also requires making breaking changes into on-disk file formats that use a uid --- for example, /etc/passwd, /etc/group, utmp/wtmp, etc. If it will also break compatibility with remote file systems that don't use a Windows SID --- e.g., nfsv3, AFS, etc. And that's before we even get to breaking things like tar files, etc. I'll also note that customers that are most likely to need to use the abominationm of Windows SIDs are also those that are likely to be using proprietary third party binaries --- you know, silly things like SAP R/3, Oracle Enterprise Database, db2, etc. And if you use Windows SIDs as user id's in your /etc/passwd, then binaries that are still using the traditional system calls will get the overflow 32-bit number --- and break. I suspect it will be much more useful to simply add a supplementary user id and group id which is only used by those file systems that *care* about Windows SID's, and assume that everything else will use true, traditional Unix uids and gids. I also suspect that we should be stashing the supplementary id's as extended attributes for the file systems. That way we can much more quickly and easily add support to ext4, xfs, btrfs, etc., as file systems that can be used as backing stores for NFSv4 and CIFS for those (few) environments that care about Windows SID's. - Ted P.S., From my perspective, Windows SID's are actually the legacy ID's. especially as more and more people flee Microslop's Windows 11 and moving to Linux and MacOS. :-)