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SubjectRe:Re: [PATCH resend] kernel: Make taskstats available via genetlink per namespace
>>> -sh-4.4# ./getdelays -d -p 186 -v
>>> print delayacct stats ON
>>> debug on
>>> Error getting family id, errno 0
>>> As more and more applications are deployed in containers like Docker,
>>> it is necessary to support getdelays to be used in net namespace.
>>> Taskstats is safe for use per namespace as genetlink checks the
>>> capability of namespace message by netlink_ns_capable().
>>> Make taskstats available via genetlink per namespace.
>> Let me add a polite nack to this patch.
>> Taskstats is completely senseless in a network namespace. There is no
>> translation of identifiers into the context of the receiver of the
>> message.
>The interface of taskstats is genetlink that is sensible in net namsespace.
>> To make this work requires updating the taskstats code to do something
>> sensible when in a pid namespace, as well as when in a network
>> namespace.
> Yes. Taskstats already does convert the input process ID into the task in the
> correspoding pid namsespace. Do you mean to add some check of current user's
> capability like SYS_ADMIN or else?

Actually, here, I think it's meaningful to set the genl_family's netnsok of Taskstat
as true. As you said, Taskstats itself is senseless in a network namespace. So, we
don't have to limit it to the only init_net_ns, it is basically okay to make it
available in all network namespace. Certainly, maybe taskstats itself also needs to
updated, because it does seem to be missing something to just use CAP_NET_ADMIN as the
acquisition restriction of taskstat.

xu xin

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