From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.6 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 474F9C3F2C6 for ; Tue, 3 Mar 2020 11:34:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id EA2D820857 for ; Tue, 3 Mar 2020 11:34:00 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="key not found in DNS" (0-bit key) header.d=szeredi.hu header.i=@szeredi.hu header.b="BDwb6Aqr" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727922AbgCCLeA (ORCPT ); Tue, 3 Mar 2020 06:34:00 -0500 Received: from mail-il1-f195.google.com ([209.85.166.195]:32894 "EHLO mail-il1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726661AbgCCLeA (ORCPT ); Tue, 3 Mar 2020 06:34:00 -0500 Received: by mail-il1-f195.google.com with SMTP id r4so2478302iln.0 for ; Tue, 03 Mar 2020 03:34:00 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=szeredi.hu; s=google; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=6byiiSiBg+O9qfUoKK2ksV0ZQAH63X1Hb8rEqsCdvnA=; b=BDwb6Aqrx0xtaZxAiJzRl8XeyjQnOY6DfKQWnfKlSJyw80tDndkNTO1YIRtxXiY32u jX+rF79QYJ93n6uKhvAsKktrD0A98qVn8g0o2FP4zpYgjGgDbSp4ye0NeZ/S6xaEu/9P jinoTbqOhlXGvA2nE26OcaLpGlhLDzhcnIkuA= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=6byiiSiBg+O9qfUoKK2ksV0ZQAH63X1Hb8rEqsCdvnA=; b=IRcwfB8cgC2LOXfoSf66kmFBBW+t3Dh+5ObSGN1va7I8h8O4qchzfhr/2xu/H2jvjS it+BNwV5xCWlcNlhk2/5UW196KYiFbag3T8OpiCTm1GbTFZihmTIZFiucoIVHd3+Lx2F oKtDWAqh/eSA6fJ95XulRsxHyIxsG20y4UCQBTIQbW0mVcipevdEe1DmFqQztDAv58L6 rloKVvscQS6NGhYaRMHsMrNJbaZsjfpWL39LSYgSZj0GKHoeZe0gJ32aX0DKY/r+SmTk qism5An7zvL2fPP2bjsv2IcC1CotT6JB42tFnfIVnpmcQx1HGPs703BIcvNfMhZRcl9L +plQ== X-Gm-Message-State: ANhLgQ0fG4SSj/xV3ahg8V23zugtCcriYCpmTv6chjXKNns19rfDHnRm N17bwUeOrOG5gFHZpGFWdSQ1n4l4uNh4sZ9oljpqoA== X-Google-Smtp-Source: ADFU+vtdZi1ZHmFd0i6HeNGyBbTzdkdeTY8UruU2lDGdtfEbDHYjU8QcXctIQ1YFTTxOKq3DU5hMTC1oZ34IhqBV7I8= X-Received: by 2002:a92:89cb:: with SMTP id w72mr4195534ilk.252.1583235239625; Tue, 03 Mar 2020 03:33:59 -0800 (PST) MIME-Version: 1.0 References: <1582644535.3361.8.camel@HansenPartnership.com> <20200228155244.k4h4hz3dqhl7q7ks@wittgenstein> <107666.1582907766@warthog.procyon.org.uk> <0403cda7345e34c800eec8e2870a1917a8c07e5c.camel@themaw.net> <1509948.1583226773@warthog.procyon.org.uk> <20200303100045.zqntjjjv6npvs5zl@wittgenstein> <20200303102541.diud7za3vvjvqco4@wittgenstein> In-Reply-To: <20200303102541.diud7za3vvjvqco4@wittgenstein> From: Miklos Szeredi Date: Tue, 3 Mar 2020 12:33:48 +0100 Message-ID: Subject: Re: [PATCH 00/17] VFS: Filesystem information and notifications [ver #17] To: Christian Brauner Cc: David Howells , Ian Kent , James Bottomley , Steven Whitehouse , Miklos Szeredi , viro , Christian Brauner , Jann Horn , "Darrick J. Wong" , Linux API , linux-fsdevel , lkml , Greg Kroah-Hartman Content-Type: text/plain; charset="UTF-8" Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Tue, Mar 3, 2020 at 11:25 AM Christian Brauner wrote: > > On Tue, Mar 03, 2020 at 11:13:50AM +0100, Miklos Szeredi wrote: > > On Tue, Mar 3, 2020 at 11:00 AM Christian Brauner > > wrote: > > > More magic links to beam you around sounds like a bad idea. We had a > > > bunch of CVEs around them in containers and they were one of the major > > > reasons behind us pushing for openat2(). That's why it has a > > > RESOLVE_NO_MAGICLINKS flag. > > > > No, that link wouldn't beam you around at all, it would end up in an > > internally mounted instance of a mountfs, a safe place where no > > Even if it is a magic link to a safe place it's a magic link. They > aren't a great solution to this problem. fsinfo() is cleaner and > simpler as it creates a context for a supervised mount which gives the a > managing application fine-grained control and makes it easily > extendable. Yeah, it's a nice and clean interface in the ioctl(2) sense. Sure, fsinfo() is way better than ioctl(), but it at the core it's still the same syscall multiplexer, do everything hack. > Also, we're apparently at the point where it seems were suggesting > another (pseudo)filesystem to get information about filesystems. Implementation detail. Why would you care? Thanks, Miklos