Re: [PATCH net 2/2] sctp: set new_asoc temp when processing dupcookie

[Vlad Yasevich <vyasevic@redhat.com>]

On 05/23/2017 01:28 AM, Xin Long wrote:
> After sctp changed to use transport hashtable, a transport would be
> added into global hashtable when adding the peer to an asoc, then
> the asoc can be got by searching the transport in the hashtbale.
> 
> The problem is when processing dupcookie in sctp_sf_do_5_2_4_dupcook,
> a new asoc would be created. A peer with the same addr and port as
> the one in the old asoc might be added into the new asoc, but fail
> to be added into the hashtable, as they also belong to the same sk.
> 
> It causes that sctp's dupcookie processing can not really work.
> 
> Since the new asoc will be freed after copying it's information to
> the old asoc, it's more like a temp asoc. So this patch is to fix
> it by setting it as a temp asoc to avoid adding it's any transport
> into the hashtable and also avoid allocing assoc_id.
> 
> An extra thing it has to do is to also alloc stream info for any
> temp asoc, as sctp dupcookie process needs it to update old asoc.
> But I don't think it would hurt something, as a temp asoc would
> always be freed after finishing processing cookie echo packet.
> 
> Reported-by: Jianwen Ji <jiji@redhat.com>
> Signed-off-by: Xin Long <lucien.xin@gmail.com>

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

-vlad

> ---
>  net/sctp/sm_make_chunk.c | 13 ++++---------
>  net/sctp/sm_statefuns.c  |  3 +++
>  2 files changed, 7 insertions(+), 9 deletions(-)
> 
> diff --git a/net/sctp/sm_make_chunk.c b/net/sctp/sm_make_chunk.c
> index 8a08f13..92e332e 100644
> --- a/net/sctp/sm_make_chunk.c
> +++ b/net/sctp/sm_make_chunk.c
> @@ -2454,16 +2454,11 @@ int sctp_process_init(struct sctp_association *asoc, struct sctp_chunk *chunk,
>  	 * stream sequence number shall be set to 0.
>  	 */
>  
> -	/* Allocate storage for the negotiated streams if it is not a temporary
> -	 * association.
> -	 */
> -	if (!asoc->temp) {
> -		if (sctp_stream_init(asoc, gfp))
> -			goto clean_up;
> +	if (sctp_stream_init(asoc, gfp))
> +		goto clean_up;
>  
> -		if (sctp_assoc_set_id(asoc, gfp))
> -			goto clean_up;
> -	}
> +	if (!asoc->temp && sctp_assoc_set_id(asoc, gfp))
> +		goto clean_up;
>  
>  	/* ADDIP Section 4.1 ASCONF Chunk Procedures
>  	 *
> diff --git a/net/sctp/sm_statefuns.c b/net/sctp/sm_statefuns.c
> index 4f5e6cf..f863b55 100644
> --- a/net/sctp/sm_statefuns.c
> +++ b/net/sctp/sm_statefuns.c
> @@ -2088,6 +2088,9 @@ sctp_disposition_t sctp_sf_do_5_2_4_dupcook(struct net *net,
>  		}
>  	}
>  
> +	/* Set temp so that it won't be added into hashtable */
> +	new_asoc->temp = 1;
> +
>  	/* Compare the tie_tag in cookie with the verification tag of
>  	 * current association.
>  	 */
>