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SubjectRe: Re: [PATCH v3 0/3] auth_gss: netns refcount leaks when use-gss-proxy==1
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在 2019/8/2 3:53, J. Bruce Fields 写道:
> 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
These patchsets don't seem to merge into the mainline, are there any
other patches that fix this bug?

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