From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id D16A11FBF; Wed, 21 Feb 2024 01:22:59 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=90.155.50.34 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1708478581; cv=none; b=nss9/AhKtmOxZE0GKf7ItbslhgRIY60quZlhP/R020er0ngvv38JiRyn75BvWxjQlW/vfKBqHXLiQjCJWA7+8kjsk89Ot3nR6c/+BT+FC9jkhejbhKUe2xH/sieAKn9kKrNXpp7PonbSivo4AYJG7KAieEf8k2WLoBuKI8O/Vlg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1708478581; c=relaxed/simple; bh=7yS5lMeSRHcZCY+R3rXcc46JX8Us1L4l71PPlss2OYg=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=MG56CmzuOrzXv3CZnAjnVtvXmD4IF6Xj+SmUXFOxa7YIOXwiODjvDCoWnSlxO7zw9UvRXRc/93VMjMD8qRBEiRhRHFOxVuBz/sPYlfX/NrzNG7f+O2/FIOPQF9cAML7crfRW3e3DAyN4jDZo21z7KxVkXxrhdoHlxD6qW1ruN/8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org; spf=none smtp.mailfrom=infradead.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b=kYw++rJW; arc=none smtp.client-ip=90.155.50.34 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=infradead.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="kYw++rJW" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=ocYsSgxQit1IpReHX6MZ9VRl0UEjxazch658LWW9u80=; b=kYw++rJWJg6b/DYb1+XV0p9E4B Wej+4M6foMiwDRQ8sFttmmpagkp7awqT8qvexCdHte80cTqN0jQT7NUbL5f1uI4rCi23GO3ZBd8Yn WvAyLs7XKHS/i43VzPHlbmr/v7GBiMI4zXSiKHQuj5KgNRBW4Kz5GvySy/0zpcPdTzw9I+q1LVBpG gzJiy7ezViF4W3/Yl8IFP0rbnDHzT4/Ah0QqwNpERofZf5olICUE0JMznZurRpTUAwSjdPFYiGHgq hRjLO2eJEk5l8cnlo1UtWOPuAl/YJ/N/itAlHSxQvCyNLa3j1rnLbDCxIozO4dsxI2cG4vRp8B1vx E4OTVBoA==; Received: from willy by casper.infradead.org with local (Exim 4.97.1 #2 (Red Hat Linux)) id 1rcbK3-0000000H35s-2TNo; Wed, 21 Feb 2024 01:22:55 +0000 Date: Wed, 21 Feb 2024 01:22:55 +0000 From: Matthew Wilcox To: Kent Overstreet Cc: James Bottomley , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, lsf-pc@lists.linux-foundation.org, Christian Brauner , =?iso-8859-1?Q?St=E9phane?= Graber Subject: Re: [LSF TOPIC] beyond uidmapping, & towards a better security model Message-ID: References: <141b4c7ecda2a8c064586d064b8d1476d8de3617.camel@HansenPartnership.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Tue, Feb 20, 2024 at 07:25:58PM -0500, Kent Overstreet wrote: > But there's real advantages to getting rid of the string <-> integer > identifier mapping and plumbing strings all the way through: > > - creating a new sub-user can be done with nothing more than the new > username version of setuid(); IOW, we can start a new named subuser > for e.g. firefox without mucking with _any_ system state or tables > > - sharing filesystems between machines is always a pita because > usernames might be the same but uids never are - let's kill that off, > please I feel like we need a bit of a survey of filesystems to see what is already supported and what are desirable properties. Block filesystems are one thing, but network filesystems have been dealing with crap like this for decades. I don't have a good handle on who supports what at this point. As far as usernames being the same ... well, maybe. I've been willy, mrw103, wilma (twice!), mawilc01 and probably a bunch of others I don't remember. I don't think we'll ever get away from having a mapping between different naming authorities.