[Swan-dev] IKEv2 rekey initiator failures
Antony Antony
antony at phenome.org
Wed Apr 8 17:16:08 UTC 2020
On Wed, Apr 08, 2020 at 10:07:43AM -0400, Andrew Cagney wrote:
>
>
> On Wed, 8 Apr 2020 at 02:29, Antony Antony <antony at phenome.org> wrote:
>
> Hi,
>
> I am hunting a couple of corner cases, IKEv2 rekey initiator failures.
> These issues appear when testing clones. Think of 100 IKEv2 Child SAs under
> one IKE SA and rekeying them all. In the test rekey margin and salife are
> short. Short values do not matter, because looking back in Tuomo production
> systems logs, with larger rekey margin and saflifetime, I see the same
> issues.
>
> First one is possibly fixed.
>
> https://testing.libreswan.org/v3.30-418-g2a5319bd84-master/
> ikev2-child-rekey-07-deadlock/OUTPUT/west.pluto.log.gz
>
>
>
> ikev2: insert new v2D message to the tail of pending v2D requests
>
> It's certainly better:
>
> optimized to send out v2D message before v2_CREATE_CHILD_SA jobs.
> Delete would also get a quicker response from the other end, because,
> there are no crypto operations i.e. v2DH,KE,nonce to respond to
> a v2_INFORMATIONAL request.
>
> but is it needed?
I noticed sometimes a several rekeys would get queued up. And delete would
stay in the queue for longer. I think it is best to prioritize v2D ahead
CREATE_CHILD_SA. Also can't think of any side effect of pritorizing v2D.
> this queue may have v2_CREATE_CHILD_SA or/and v2_INFORMATIONAL (v2D).
> add new v2_INFORMATIONAL, v2D request to the tail of v2D requests,
> instead adding to the tail of the queue.
>
> I'm also puzzled by:
yes. It seems necessary for now. May be there could a way to call
complete_v2_state_transition().
> if (IS_CHILD_SA_ESTABLISHED(st)) {
> /*
> * this is a continuation of delete message.
> * shortcut complete_v2_state_transition()
> * to call complete_v2_state_transition, need more work
> */
> pending.cb(ike, st, NULL);
Initially I imagined calling complete_v2_state_transition() would be
cleaner, however it turned out to be harder. There are too many checks
inside complete_v2_state_transition() and success_v2_state_transition() that
would fail, or need hacks or fixes.
Initiatiing INFROMATIONAL v2D does not have an svm entry or fake md. I am
not sure faking all that is worth it.
Message ID is already advanced in send_delete()
Now I am thinking a lighter version complete_v2_state_transition() is
probably ideal this.
when completeing an v2D all we really need is the next line.
> v2_msgid_schedule_next_initiator(ike);
>
> Second One seems to harder to trace. Here are the symptoms that I found so
> far. Rekaying IPsec fails with the following message and the connections
> disappears. If you have auto=route it may come back again. auto=route is a
> bandaid.
>
> Apr 6 13:58:50.367487: | ikev2_child_sa_respond returned
> STF_INTERNAL_ERROR
>
>
>
> Any ideas on what triggered the internal error?
I know one step further. the line shown bellow "EVENT_SA_EXPIRE, timeout in
0 seconds" is the cause. However, I don't why pluto schedule this
EVENT_SA_EXPIRE.
Did you look a the log?
>
> Apr 6 13:58:50.367426: "west/68x0" #3699: CHILD SA to rekey #3500 vanished
> abort this exchange
>
> the internal error seems to caused EVENT_SA_EXPIRE, timeout in 0 seconds
> which removed predecessor state before rekey send the message.
>
> Apr 6 13:58:50.237455: | inserting event EVENT_SA_EXPIRE, timeout in 0
> seconds for #3500
>
> Apr 6 13:58:50.230304: | duplicating state object #3606 "west/100x0" as
> #3699 for IPSEC SA
> Apr 6 13:58:50.226728: | handling event EVENT_SA_REPLACE for child state #
> 3500
>
> It seems when replace is hit, code decided to rekey, and also scheduled an
> EXPIRE. Usually margin is 70s or so Which is enough to rekey. In this case
> it margin end as 0.
>
> Bellow is link to full log of test ikev2-child-rekey-08-deadlock. I ran it
> manually for longer time. It took 58 minutes before this error to occured.
>
> WARNING: the following log is big 100s Mega bytes, careful when clicking on
> the link in a browser. It is better to download it using wget to read.
>
> https://swantest.libreswan.fi/s2/ikev2-child-rekey-08-deadlock/OUTPUT/
> west.pluto.log.gz
>
> I let the test run, it happend twice in about 6 hours.
>
> Apr 6 13:58:50.367426: "west/68x0" #3699: CHILD SA to rekey #3500 vanished
> abort this exchange
> Apr 6 17:49:44.228126: "west/39x0" #18513: CHILD SA to rekey #18320
> vanished abort this exchange
>
> Looking back in older logs, Tuomo's log, I see the same sequence and
> connrection restarting either due to keying tries or traffic. He is running
> with default rekey margin and fuzz, while the test has shorter rekey
> margin. Note it is not just because of shorter rekey margin or salifetime.
>
> The oldest seems to hapeend in
>
> "Apr 18 00:57:47 foo-gw pluto[5139]: "antony-ams" #915: Child SA to rekey #
> 912 vanished abort this exchange"
>
> I am wondering where is the bug? pluto's rekey margin calcuation, or some
> other logic forcing the EXPIRE event.
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