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 B85E47B3EA; Sat, 17 Feb 2024 22:31:38 +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=1708209100; cv=none; b=Ce30GfuBKOaoey96h3qbU6Nd8fEnF1z/R+Rm4HMIgHaTwxXNS5T4Q0v33kJEaRlIo8KogohQ/ti2S8sFHSeRygbzvWUsoMFhBkRD5dKZpLs+Tk4EYOr1UzwT16cmvsNTYZxuqCmuVt4M10PQsulhxlPxEyoRQCDoYIFzvxagUng= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1708209100; c=relaxed/simple; bh=ybGYd3rkq0s1hALMfpQk6n3C/edebolky5vSvPyxlIY=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=SuUXCXCs5VHIXPeywqYB3LGIT2cik8b38b84l+ECRATm+4Qv3C1V7fr8wOJfQsgUlj0DOL3bzHS1ayvBVuCzp/MfXVfysTSSTH33o6SUGvef3ZIcGwV6YtJtZJzI8qQyBhufV3nQRYvwDuJRLDROrVmy+5dl4FCnM5n/k6eQtRo= 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=DKSJtTBA; 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="DKSJtTBA" 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=1L5+v7OBH94VXAhT9gGEjSneA+Vgh7K9gZNcifYCc80=; b=DKSJtTBAkswcEe7Kk2lO3rR4Lk WQWPIevzHKMWJSC7wA9zx3XPh45lG/eo55hW87G0yTnqR/UxCam5NdReiafiYJatVdUeQVsWe1/g5 aQLjvRXAzE8IDhVRImnDXZLzyMxv+DgPAPLn7L/S5p6GblfXsBl0t9JlzQ9pmMISCoVGUYk7f9cWb GSnzl8uX7Wxc/4GUJx/nKssfxIzN4JF1TYoVh8tfYG/V4hBafyLRhb/9UE5faVMREqSUw6VxBOM5o hfeSr6FuL9hLBBz3yBlQri83nyhnjARgvfOIpmXOx13lNNio/ERDs8OW7RD4vFxSIC0krR5cR+3/k usUPrjgA==; Received: from willy by casper.infradead.org with local (Exim 4.97.1 #2 (Red Hat Linux)) id 1rbTDV-00000008YDo-44mW; Sat, 17 Feb 2024 22:31:30 +0000 Date: Sat, 17 Feb 2024 22:31:29 +0000 From: Matthew Wilcox To: Kent Overstreet Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, lsf-pc@lists.linux-foundation.org Subject: Re: [LSF TOPIC] beyond uidmapping, & towards a better security model Message-ID: References: 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 Sat, Feb 17, 2024 at 03:56:40PM -0500, Kent Overstreet wrote: > AKA - integer identifiers considered harmful Sure, but how far are you willing to take this? You've recently been complaining about inode numbers: https://lore.kernel.org/linux-fsdevel/20231211233231.oiazgkqs7yahruuw@moria.home.lan/ > The solution (originally from plan9, of course) is - UIDs shouldn't be > numbers, they should be strings; and additionally, the strings should be > paths. > > Then, if 'alice' is a user, 'alice.foo' and 'alice.bar' would be > subusers, created by alice without any privileged operations or mucking > with outside system state, and 'alice' would be superuser w.r.t. > 'alice.foo' and 'alice.bar'. Waitwaitwait. You start out saying "they are paths" and then you use '.' as the path separator. I mean, I come from a tradition that *does* use '.' as the path separator (RISC OS, from Acorn DFS, which I believe was influenced by the Phoenix command interpreter), but Unix tends to use / as the separator. One of the critical things about plan9 that means you have to think hard before transposing its ideas to Linux is that it doesn't have suid programs. So if I create willy/root, it's essential that a program which is suid only becomes suid with respect to other programs inside willy's domain. And it doesn't just apply to filesystem things, but "can I send signals" and dozens of other things. So there's a lot to be fleshed out here.