linux-kernel - Re: [PATCH] sctp: set association state to established in dupcook

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Date:	Thu, 24 Jan 2013 09:34:30 +0800
From:	Xufeng Zhang <xufengzhang.main@...il.com>
To:	Neil Horman <nhorman@...driver.com>
Cc:	vyasevich@...il.com, sri@...ibm.com, davem@...emloft.net,
	linux-sctp@...r.kernel.org, netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] sctp: set association state to established in dupcook_a handler

On 1/23/13, Neil Horman <nhorman@...driver.com> wrote:
> On Wed, Jan 23, 2013 at 03:38:40PM +0800, xufengzhang.main@...il.com wrote:
>> From: Xufeng Zhang <xufeng.zhang@...driver.com>
>>
>> While sctp handling a duplicate COOKIE-ECHO and the action is
>> 'Association restart', sctp_sf_do_dupcook_a() will processing
>> the unexpected COOKIE-ECHO for peer restart, but it does not set
>> the association state to SCTP_STATE_ESTABLISHED, so the association
>> could stuck in SCTP_STATE_SHUTDOWN_PENDING state forever.
>> This violates the sctp specification:
>>   RFC 4960 5.2.4. Handle a COOKIE ECHO when a TCB Exists
>>   Action
>>   A) In this case, the peer may have restarted. .....
>>      After this, the endpoint shall enter the ESTABLISHED state.
>>
>> Fix this problem by adding a SCTP_CMD_NEW_STATE cmd to the command
>> list so as to set the restart association to SCTP_STATE_ESTABLISHED
>> state properly.
>>
>> Signed-off-by: Xufeng Zhang <xufeng.zhang@...driver.com>
>> ---
>>  net/sctp/sm_statefuns.c |    2 ++
>>  1 files changed, 2 insertions(+), 0 deletions(-)
>>
>> diff --git a/net/sctp/sm_statefuns.c b/net/sctp/sm_statefuns.c
>> index 618ec7e..528f1c8 100644
>> --- a/net/sctp/sm_statefuns.c
>> +++ b/net/sctp/sm_statefuns.c
>> @@ -1779,6 +1779,8 @@ static sctp_disposition_t
>> sctp_sf_do_dupcook_a(struct net *net,
>>
>>  	/* Update the content of current association. */
>>  	sctp_add_cmd_sf(commands, SCTP_CMD_UPDATE_ASSOC, SCTP_ASOC(new_asoc));
>> +	sctp_add_cmd_sf(commands, SCTP_CMD_NEW_STATE,
>> +			SCTP_STATE(SCTP_STATE_ESTABLISHED));
>>  	sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(repl));
>>  	sctp_add_cmd_sf(commands, SCTP_CMD_EVENT_ULP, SCTP_ULPEVENT(ev));
>>  	return SCTP_DISPOSITION_CONSUME;
>> --
>> 1.7.0.2
>>
>>
>
> Looks reasonable to me, thanks
>
> nit: The RFC indicate the association should enter the ESTABLISHED state
> after
> preforming all other actions, so it seems that the state change should
> occur
> after the ULP event is sent

Good catch! I'll do what vlad suggested.
Thanks for your review!


Thanks,
Xufeng

>
> Neil
>
>
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