linux-kernel - Re: [PATCH v2] sctp: set association state to established in dupcook

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Date:	Thu, 24 Jan 2013 10:05:37 -0500
From:	Vlad Yasevich <vyasevich@...il.com>
To:	xufengzhang.main@...il.com
CC:	nhorman@...driver.com, davem@...emloft.net,
	linux-sctp@...r.kernel.org, netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] sctp: set association state to established in dupcook_a
 handler

On 01/23/2013 09:44 PM, 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.
>
> To resolve this problem, adding a SCTP_CMD_NEW_STATE cmd to the
> command list before SCTP_CMD_REPLY cmd, this will set the restart
> association to SCTP_STATE_ESTABLISHED state properly and also avoid
> I-bit being set in the DATA chunk header when COOKIE_ACK is bundled
> with DATA chunks.
>
> Signed-off-by: Xufeng Zhang <xufeng.zhang@...driver.com>

Acked-by: Vlad Yasevich <vyasevich@...il.com>

-vlad

> ---
> v2:
> - Put the SCTP_CMD_NEW_STATE command before SCTP_CMD_REPLY and after SCTP_CMD_EVENT_ULP
>    suggested by Vlad and Neil
> - Improve the last paragraph of the commit header
>
>   net/sctp/sm_statefuns.c |    4 +++-
>   1 files changed, 3 insertions(+), 1 deletions(-)
>
> diff --git a/net/sctp/sm_statefuns.c b/net/sctp/sm_statefuns.c
> index 618ec7e..5131fcf 100644
> --- a/net/sctp/sm_statefuns.c
> +++ b/net/sctp/sm_statefuns.c
> @@ -1779,8 +1779,10 @@ 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_REPLY, SCTP_CHUNK(repl));
>   	sctp_add_cmd_sf(commands, SCTP_CMD_EVENT_ULP, SCTP_ULPEVENT(ev));
> +	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));
>   	return SCTP_DISPOSITION_CONSUME;
>
>   nomem_ev:
>

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