sctp: implement validate_data for sctp_stream_interleave

validate_data is added as a member of sctp_stream_interleave, used
to validate ssn/chunk type for data or mid (message id)/chunk type
for idata, called in sctp_eat_data.

If this check fails, an abort packet will be sent, as said in
section 2.2.3 of RFC8260.

It also adds the process for idata in rx path. As Marcelo pointed
out, there's no need to add event table for idata, but just share
chunk_event_table with data's. It would drop data chunk for idata
and drop idata chunk for data by calling validate_data in
sctp_eat_data.

As last patch did, it also replaces sizeof(struct sctp_data_chunk)
with sctp_datachk_len for rx path.

After this patch, the idata can be accepted and delivered to ulp
layer.

Signed-off-by: Xin Long <lucien.xin@gmail.com>
Acked-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Acked-by: Neil Horman <nhorman@tuxdriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 39 insertions, 0 deletions

diff --git a/net/sctp/stream_interleave.c b/net/sctp/stream_interleave.c
index 3ac47e78c013..3d8733be6f7a 100644
--- a/net/sctp/stream_interleave.c
+++ b/net/sctp/stream_interleave.c
@@ -92,11 +92,49 @@ static void sctp_chunk_assign_mid(struct sctp_chunk *chunk)
 	}
 }
 
+static bool sctp_validate_data(struct sctp_chunk *chunk)
+{
+	const struct sctp_stream *stream;
+	__u16 sid, ssn;
+
+	if (chunk->chunk_hdr->type != SCTP_CID_DATA)
+		return false;
+
+	if (chunk->chunk_hdr->flags & SCTP_DATA_UNORDERED)
+		return true;
+
+	stream = &chunk->asoc->stream;
+	sid = sctp_chunk_stream_no(chunk);
+	ssn = ntohs(chunk->subh.data_hdr->ssn);
+
+	return !SSN_lt(ssn, sctp_ssn_peek(stream, in, sid));
+}
+
+static bool sctp_validate_idata(struct sctp_chunk *chunk)
+{
+	struct sctp_stream *stream;
+	__u32 mid;
+	__u16 sid;
+
+	if (chunk->chunk_hdr->type != SCTP_CID_I_DATA)
+		return false;
+
+	if (chunk->chunk_hdr->flags & SCTP_DATA_UNORDERED)
+		return true;
+
+	stream = &chunk->asoc->stream;
+	sid = sctp_chunk_stream_no(chunk);
+	mid = ntohl(chunk->subh.idata_hdr->mid);
+
+	return !MID_lt(mid, sctp_mid_peek(stream, in, sid));
+}
+
 static struct sctp_stream_interleave sctp_stream_interleave_0 = {
 	.data_chunk_len		= sizeof(struct sctp_data_chunk),
 	/* DATA process functions */
 	.make_datafrag		= sctp_make_datafrag_empty,
 	.assign_number		= sctp_chunk_assign_ssn,
+	.validate_data		= sctp_validate_data,
 };
 
 static struct sctp_stream_interleave sctp_stream_interleave_1 = {
@@ -104,6 +142,7 @@ static struct sctp_stream_interleave sctp_stream_interleave_1 = {
 	/* I-DATA process functions */
 	.make_datafrag		= sctp_make_idatafrag_empty,
 	.assign_number		= sctp_chunk_assign_mid,
+	.validate_data		= sctp_validate_idata,
 };
 
 void sctp_stream_interleave_init(struct sctp_stream *stream)