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From: Cong Wang <xiyou.wangcong@gmail.com>
To: Stephen Smalley <sds@tycho.nsa.gov>
Cc: Linux Kernel Network Developers <netdev@vger.kernel.org>,
	Elad Raz <e@eladraz.com>, Paul Moore <paul@paul-moore.com>,
	Richard Guy Briggs <rgb@redhat.com>
Subject: Re: [Patch net] net: saving irq context for peernet2id()
Date: Thu, 20 Oct 2016 11:29:11 -0700	[thread overview]
Message-ID: <CAM_iQpWD3WiX1ZX+3LJ8vbJc42K1jZcZ4-f6MO5kzZY-+Szkqw@mail.gmail.com> (raw)
In-Reply-To: <2707c52d-88ec-7b93-f96e-eeaffc952c9c@tycho.nsa.gov>

On Thu, Oct 20, 2016 at 7:58 AM, Stephen Smalley <sds@tycho.nsa.gov> wrote:
> On 10/20/2016 02:52 AM, Cong Wang wrote:
>> A kernel warning inside __local_bh_enable_ip() was reported by people
>> running SELinux, this is caused due to some SELinux functions
>> (indirectly) call peernet2id() with IRQ disabled in process context,
>> when we re-enable BH with IRQ disabled kernel complains. Shut up this
>> warning by saving IRQ context in peernet2id(), BH is still implicitly
>> disabled.
>
> Not sure this suffices; kill_fasync() -> send_sigio() ->
> send_sigio_to_task() -> sigio_perm() -> security_file_send_sigiotask()
> -> selinux_file_send_sigiotask() -> ... -> audit_log() -> ... ->
> peernet2id()

Oh, this is a new one. kill_fasync() is called in IRQ handler, so we actually
do multicast in IRQ context.... It makes no sense, netlink multicast could
be very expensive if we have many listeners.

I am Cc'ing Richard who added that multicast in audit_log_end(). It seems
not easy to just move the multicast to a workqueue, since the skb is copied
from audit_buffer which is freed immediately after that, probably need another
queue like audit_skb_queue.

  reply	other threads:[~2016-10-20 18:29 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-10-20  6:52 [Patch net] net: saving irq context for peernet2id() Cong Wang
2016-10-20 10:17 ` Nicolas Dichtel
2016-10-20 17:17   ` Cong Wang
2016-10-20 14:58 ` Stephen Smalley
2016-10-20 18:29   ` Cong Wang [this message]
2016-10-20 19:04     ` Cong Wang
2016-10-20 19:07     ` Paul Moore
2016-10-20 23:35       ` Cong Wang
2016-10-21  4:47         ` Cong Wang
2016-10-21 13:51           ` Stephen Smalley
2016-10-21 16:19         ` Paul Moore
2016-10-21 18:02           ` Cong Wang
2016-10-21 19:39             ` Richard Guy Briggs
2016-10-21 20:15               ` Paul Moore
2016-10-21 20:33                 ` David Miller
2016-10-21 20:53                   ` Paul Moore
2016-10-22  1:55                     ` Paul Moore
2016-10-22  3:34                       ` Cong Wang
2016-10-22  3:53                   ` Cong Wang
2016-10-21 20:03             ` Paul Moore
2016-10-22  3:26               ` Cong Wang
2016-10-22 19:02                 ` Paul Moore

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