From mboxrd@z Thu Jan 1 00:00:00 1970 From: ebiederm@xmission.com (Eric W. Biederman) Subject: netlink scm creds uid and gids are always 0. Date: Thu, 23 Aug 2012 23:45:04 -0700 Message-ID: <871uiwlrf3.fsf@xmission.com> Mime-Version: 1.0 Content-Type: text/plain Cc: To: Eric Dumazet Return-path: Received: from out01.mta.xmission.com ([166.70.13.231]:59446 "EHLO out01.mta.xmission.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753243Ab2HXGpP (ORCPT ); Fri, 24 Aug 2012 02:45:15 -0400 Sender: netdev-owner@vger.kernel.org List-ID: While working on the kuid_t and kgid_t conversion of the audit subsystem I noticed that since the performance problem of scm creds and af_unix sockets were fixed af_netlink sockets have not filled in the uid or gid of the originator of the socket. I think all we need is an appropriate cred_to_ucred call to fix this regression, but I am going so many different directions right now I can't get myself to focus on this long enough to work up an appripriate patch to fix. Eric do you think you might take a gander? The commit where this regression was introduced appears to be. commit 16e5726269611b71c930054ffe9b858c1cea88eb Author: Eric Dumazet Date: Mon Sep 19 05:52:27 2011 +0000 af_unix: dont send SCM_CREDENTIALS by default Since commit 7361c36c5224 (af_unix: Allow credentials to work across user and pid namespaces) af_unix performance dropped a lot. This is because we now take a reference on pid and cred in each write(), and release them in read(), usually done from another process, eventually from another cpu. This triggers false sharing.