Re: [PATCH net-next 3/8] sctp: implement validate_ftsn for sctp_stream_interleave

[Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>]

On Tue, Dec 12, 2017 at 05:25:54PM +0800, Xin Long wrote:
...
> --- a/net/sctp/sm_statetable.c
> +++ b/net/sctp/sm_statetable.c
> @@ -992,7 +992,8 @@ static const struct sctp_sm_table_entry *sctp_chunk_event_lookup(
>  		return &chunk_event_table[cid][state];
>  
>  	if (net->sctp.prsctp_enable) {
> -		if (cid == SCTP_CID_FWD_TSN)
> +		if (cid == SCTP_CID_FWD_TSN ||
> +		    (net->sctp.intl_enable && cid == SCTP_CID_I_FWD_TSN))

We don't really need to check intl_enable here, do we?
Because a) it should actually look like:
-		if (cid == SCTP_CID_FWD_TSN)
+		if ((!net->sctp.intl_enable && cid == SCTP_CID_FWD_TSN) ||
+		    (net->sctp.intl_enable && cid == SCTP_CID_I_FWD_TSN))
but b) we will validate the chunk format/feature later with
validate_ftsn(), similarly to what happens with data chunks, so it
seems the check on intl_enable here is not necessary.

Same happens with data chunks, btw.

>  			return &prsctp_chunk_event_table[0][state];
>  	}
>  
> diff --git a/net/sctp/stream_interleave.c b/net/sctp/stream_interleave.c
> index 2ead372..cc4a5e3 100644
> --- a/net/sctp/stream_interleave.c
> +++ b/net/sctp/stream_interleave.c
> @@ -1153,8 +1153,49 @@ static void sctp_generate_iftsn(struct sctp_outq *q, __u32 ctsn)
>  	}
>  }
>  
> +#define _sctp_walk_ifwdtsn(pos, chunk, end) \
> +	for (pos = chunk->subh.ifwdtsn_hdr->skip; \
> +	     (void *)pos < (void *)chunk->subh.ifwdtsn_hdr->skip + (end); pos++)
> +
> +#define sctp_walk_ifwdtsn(pos, ch) \
> +	_sctp_walk_ifwdtsn((pos), (ch), ntohs((ch)->chunk_hdr->length) - \
> +					sizeof(struct sctp_ifwdtsn_chunk))
> +
> +static bool sctp_validate_fwdtsn(struct sctp_chunk *chunk)
> +{
> +	struct sctp_fwdtsn_skip *skip;
> +	__u16 incnt;
> +
> +	if (chunk->chunk_hdr->type != SCTP_CID_FWD_TSN)
> +		return false;
> +
> +	incnt = chunk->asoc->stream.incnt;
> +	sctp_walk_fwdtsn(skip, chunk)
> +		if (ntohs(skip->stream) >= incnt)
> +			return false;
> +
> +	return true;
> +}
> +
> +static bool sctp_validate_iftsn(struct sctp_chunk *chunk)
> +{
> +	struct sctp_ifwdtsn_skip *skip;
> +	__u16 incnt;
> +
> +	if (chunk->chunk_hdr->type != SCTP_CID_I_FWD_TSN)
> +		return false;
> +
> +	incnt = chunk->asoc->stream.incnt;
> +	sctp_walk_ifwdtsn(skip, chunk)
> +		if (ntohs(skip->stream) >= incnt)
> +			return false;
> +
> +	return true;
> +}
> +
>  static struct sctp_stream_interleave sctp_stream_interleave_0 = {
>  	.data_chunk_len		= sizeof(struct sctp_data_chunk),
> +	.ftsn_chunk_len		= sizeof(struct sctp_fwdtsn_chunk),
>  	/* DATA process functions */
>  	.make_datafrag		= sctp_make_datafrag_empty,
>  	.assign_number		= sctp_chunk_assign_ssn,
> @@ -1166,10 +1207,12 @@ static struct sctp_stream_interleave sctp_stream_interleave_0 = {
>  	.abort_pd		= sctp_ulpq_abort_pd,
>  	/* FORWARD-TSN process functions */
>  	.generate_ftsn		= sctp_generate_fwdtsn,
> +	.validate_ftsn		= sctp_validate_fwdtsn,
>  };
>  
>  static struct sctp_stream_interleave sctp_stream_interleave_1 = {
>  	.data_chunk_len		= sizeof(struct sctp_idata_chunk),
> +	.ftsn_chunk_len		= sizeof(struct sctp_ifwdtsn_chunk),
>  	/* I-DATA process functions */
>  	.make_datafrag		= sctp_make_idatafrag_empty,
>  	.assign_number		= sctp_chunk_assign_mid,
> @@ -1181,6 +1224,7 @@ static struct sctp_stream_interleave sctp_stream_interleave_1 = {
>  	.abort_pd		= sctp_intl_abort_pd,
>  	/* I-FORWARD-TSN process functions */
>  	.generate_ftsn		= sctp_generate_iftsn,
> +	.validate_ftsn		= sctp_validate_iftsn,
>  };
>  
>  void sctp_stream_interleave_init(struct sctp_stream *stream)
> -- 
> 2.1.0
> 
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