Return-Path: linux-nfs-owner@vger.kernel.org Received: from che.mayfirst.org ([209.234.253.108]:50652 "EHLO che.mayfirst.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752286Ab3HAS4D (ORCPT ); Thu, 1 Aug 2013 14:56:03 -0400 Message-ID: <51FAAF3D.3010806@fifthhorseman.net> Date: Thu, 01 Aug 2013 14:55:57 -0400 From: Daniel Kahn Gillmor MIME-Version: 1.0 To: Simo Sorce CC: David Howells , keyrings@linux-nfs.org, "Eric W. Biederman" , "Serge E. Hallyn" , linux-nfs@vger.kernel.org, krbdev@mit.edu, linux-kernel@vger.kernel.org Subject: Re: [PATCH 2/2] KEYS: Add per-user_namespace registers for persistent per-UID kerberos caches References: <20130801173846.28023.19009.stgit@warthog.procyon.org.uk> <20130801173902.28023.68819.stgit@warthog.procyon.org.uk> <51FAA0CC.7010106@fifthhorseman.net> <1375381798.15733.207.camel@willson.li.ssimo.org> In-Reply-To: <1375381798.15733.207.camel@willson.li.ssimo.org> Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="----enig2WHFTLRFBFVREFOWVNKHG" Sender: linux-nfs-owner@vger.kernel.org List-ID: This is an OpenPGP/MIME signed message (RFC 4880 and 3156) ------enig2WHFTLRFBFVREFOWVNKHG Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable On 08/01/2013 02:29 PM, Simo Sorce wrote: > It's called 'abstraction' :-) Good, I like abstraction :) >> It seems like a non-privileged user could use this to store arbitrary >> data in this keyring as a way of hiding what would otherwise be >> filesystem activity or using it for some sort of odd/sneaky IPC >> mechanism. Is this an intentional side effect? >=20 > Just as a user can add data into a shm segment ? > Is there any difference ? I guess this raises the question from a different perspective: if the kernel already supports arbitrary shm segments, filesystem locations, etc, which can be used for storing/passing opaque bytestrings between different parts of userspace, what advantages do we gain from having this new specific mechanism in the kernel? Why couldn't those parts of userspace just rely on already-existing mechanisms instead of introducing this new interface? Again, i'm not trying to say it's a bad idea; there's probably a big-picture piece of the puzzle that i don't see that makes this all obvious. i just want to understand what it is. Thanks for your explanations! Regards, --dkg ------enig2WHFTLRFBFVREFOWVNKHG Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.14 (GNU/Linux) Comment: Using GnuPG with Icedove - http://www.enigmail.net/ iQJ8BAEBCgBmBQJR+q89XxSAAAAAAC4AKGlzc3Vlci1mcHJAbm90YXRpb25zLm9w ZW5wZ3AuZmlmdGhob3JzZW1hbi5uZXRFQjk2OTEyODdBN0FEREUzNzU3RDkxMUVB NTI0MDFCMTFCRkRGQTVDAAoJEKUkAbEb/fpccfsP/1YMyvzpT0lg/Hjk7lcZQNNn dlsMz+CjD/WMSFao4Y+lYjjXXb9YF0FQFyBrAFDS5RzEyDQzz2zuuEKxv6AM3omL BHFXoPJGeJ5VlbpChJKB9vX7JK2wt8HglO6CdtkSBDqcgwJ/NuvH3SVujqlzuUGk /y2pfS2EbgN5CHnpq/okoX4b80kfPmAo1NmCG6nxPSHhVTDE2aol67HyjmFENFeQ v1nFj8NuIuY2uMO/d1wHTfdCxdKiFKLVjuaJyWTuDaMiDbnoGBAsx/99NuBA/6Z5 WkmkwKQT+fJrWbNFxHBsLuHyHiPL44RQ9HPKrOQ0rS/JVXX9VnHivN1IIplI7Qgd YdtB+SQqA+MBjavF+whg458wmiFadGQpXgFQrBYK0fsXHiZartFrbAT5+lhnkXAE +dibhXywP0B4cKsdKJDUcOijrTkgFAYkA39NdVFdVtcinjxmVBQBJgP2o2dtgWJZ IXQFM1JTdziiyuvk6MzNQLAGUjl/zoj4zzQKvRxElQ8HXWK5Yfxn9Ayb4Aa9uDJj 8+/TuCNaD/0ABp7Noz+JPu2NTlF0aylHK03wjFf3JOD7zj4jY/Nt62u1EqPPmz6M NvIeNSg40O7OR2XRUtRMKWMmDm7Zz0ytPto3/Vb5s73sSoXJCR1zEIfF6IaK9kHk mg4QtsNWAh1CzXHap4T5 =qcNT -----END PGP SIGNATURE----- ------enig2WHFTLRFBFVREFOWVNKHG--