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From: "J. Bruce Fields" <bfields@fieldses.org>
To: Wenbin Zeng <wenbin.zeng@gmail.com>
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
Date: Thu, 1 Aug 2019 15:53:46 -0400
Message-ID: <20190801195346.GA21527@fieldses.org> (raw)
In-Reply-To: <1560341370-24197-1-git-send-email-wenbinzeng@tencent.com>

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

      parent reply index

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-05-01  6:42 [PATCH " Wenbin Zeng
2019-05-01  6:42 ` [PATCH 1/3] nsfs: add evict callback into struct proc_ns_operations Wenbin Zeng
2019-05-02  3:04   ` Al Viro
2019-05-04 16:08     ` Wenbin Zeng
2019-05-01  6:42 ` [PATCH 2/3] netns: add netns_evict into netns_operations Wenbin Zeng
2019-05-04  4:10   ` David Miller
2019-05-01  6:42 ` [PATCH 3/3] auth_gss: fix deadlock that blocks rpcsec_gss_exit_net when use-gss-proxy==1 Wenbin Zeng
2019-05-09 20:52 ` [PATCH 0/3] auth_gss: netns refcount leaks " J. Bruce Fields
2019-05-10  5:09   ` Wenbin Zeng
2019-05-10  6:36 ` [PATCH v2 " Wenbin Zeng
2019-05-10  6:36   ` [PATCH v2 1/3] nsfs: add evict callback into struct proc_ns_operations Wenbin Zeng
2019-05-10  6:36   ` [PATCH v2 2/3] netns: add netns_evict into netns_operations Wenbin Zeng
2019-05-10 22:13     ` David Miller
2019-05-10  6:36   ` [PATCH v2 3/3] auth_gss: fix deadlock that blocks rpcsec_gss_exit_net when use-gss-proxy==1 Wenbin Zeng
2019-05-15  1:03   ` [PATCH v2 0/3] auth_gss: netns refcount leaks " J. Bruce Fields
2019-06-12  8:37     ` Wenbin Zeng
2019-06-12 15:52       ` J. Bruce Fields
2019-06-12 12:09 ` [PATCH v3 " Wenbin Zeng
2019-06-12 12:09   ` [PATCH v3 1/3] nsfs: add evict callback into struct proc_ns_operations Wenbin Zeng
2019-06-12 12:09   ` [PATCH v3 2/3] netns: add netns_evict into netns_operations Wenbin Zeng
2019-06-12 12:09   ` [PATCH v3 3/3] auth_gss: fix deadlock that blocks rpcsec_gss_exit_net when use-gss-proxy==1 Wenbin Zeng
2019-08-01 19:53   ` J. Bruce Fields [this message]

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