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=-2.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 5CB90C433FF for ; Thu, 1 Aug 2019 19:53:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 321BF2084C for ; Thu, 1 Aug 2019 19:53:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388761AbfHATxr (ORCPT ); Thu, 1 Aug 2019 15:53:47 -0400 Received: from fieldses.org ([173.255.197.46]:44350 "EHLO fieldses.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388679AbfHATxr (ORCPT ); Thu, 1 Aug 2019 15:53:47 -0400 Received: by fieldses.org (Postfix, from userid 2815) id E4FA21C95; Thu, 1 Aug 2019 15:53:46 -0400 (EDT) Date: Thu, 1 Aug 2019 15:53:46 -0400 From: "J. Bruce Fields" To: Wenbin Zeng Cc: davem@davemloft.net, viro@zeniv.linux.org.uk, jlayton@kernel.org, trond.myklebust@hammerspace.com, anna.schumaker@netapp.com, wenbinzeng@tencent.com, dsahern@gmail.com, nicolas.dichtel@6wind.com, willy@infradead.org, edumazet@google.com, jakub.kicinski@netronome.com, tyhicks@canonical.com, chuck.lever@oracle.com, neilb@suse.com, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, linux-nfs@vger.kernel.org Subject: Re: [PATCH v3 0/3] auth_gss: netns refcount leaks when use-gss-proxy==1 Message-ID: <20190801195346.GA21527@fieldses.org> References: <1556692945-3996-1-git-send-email-wenbinzeng@tencent.com> <1560341370-24197-1-git-send-email-wenbinzeng@tencent.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1560341370-24197-1-git-send-email-wenbinzeng@tencent.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org I lost track, what happened to these patches? --b. On Wed, Jun 12, 2019 at 08:09:27PM +0800, Wenbin Zeng wrote: > This patch series fixes an auth_gss bug that results in netns refcount > leaks when use-gss-proxy is set to 1. > > The problem was found in privileged docker containers with gssproxy service > enabled and /proc/net/rpc/use-gss-proxy set to 1, the corresponding > struct net->count ends up at 2 after container gets killed, the consequence > is that the struct net cannot be freed. > > It turns out that write_gssp() called gssp_rpc_create() to create a rpc > client, this increases net->count by 2; rpcsec_gss_exit_net() is supposed > to decrease net->count but it never gets called because its call-path is: > net->count==0 -> cleanup_net -> ops_exit_list -> rpcsec_gss_exit_net > Before rpcsec_gss_exit_net() gets called, net->count cannot reach 0, this > is a deadlock situation. > > To fix the problem, we must break the deadlock, rpcsec_gss_exit_net() > should move out of the put() path and find another chance to get called, > I think nsfs_evict() is a good place to go, when netns inode gets evicted > we call rpcsec_gss_exit_net() to free the rpc client, this requires a new > callback i.e. evict to be added in struct proc_ns_operations, and add > netns_evict() as one of netns_operations as well. > > v1->v2: > * in nsfs_evict(), move ->evict() in front of ->put() > v2->v3: > * rpcsec_gss_evict_net() directly call gss_svc_shutdown_net() regardless > if gssp_clnt is null, this is exactly same to what rpcsec_gss_exit_net() > previously did > > Wenbin Zeng (3): > nsfs: add evict callback into struct proc_ns_operations > netns: add netns_evict into netns_operations > auth_gss: fix deadlock that blocks rpcsec_gss_exit_net when > use-gss-proxy==1 > > fs/nsfs.c | 2 ++ > include/linux/proc_ns.h | 1 + > include/net/net_namespace.h | 1 + > net/core/net_namespace.c | 12 ++++++++++++ > net/sunrpc/auth_gss/auth_gss.c | 4 ++-- > 5 files changed, 18 insertions(+), 2 deletions(-) > > -- > 1.8.3.1