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sctp: add pad chunk and its make function and event table

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This chunk is defined in rfc4820#section-3, and used to pad an
SCTP packet. The receiver must discard this chunk and continue
processing the rest of the chunks in the packet.

Add it now, as it will be bundled with a heartbeat chunk to probe
pmtu in the following patches.

Signed-off-by: Xin Long <lucien.xin@gmail.com>
Acked-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Xin Long 2021-06-22 14:04:47 -04:00 committed by David S. Miller
parent aff0824dc4
commit 745a32117b
4 changed files with 57 additions and 0 deletions
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7
include/linux/sctp.h
View File

@ -98,6 +98,7 @@ enum sctp_cid {
SCTP_CID_I_FWD_TSN = 0xC2,
SCTP_CID_ASCONF_ACK = 0x80,
SCTP_CID_RECONF = 0x82,
SCTP_CID_PAD = 0x84,
}; /* enum */
@ -410,6 +411,12 @@ struct sctp_heartbeat_chunk {
};
/* PAD chunk could be bundled with heartbeat chunk to probe pmtu */
struct sctp_pad_chunk {
struct sctp_chunkhdr uh;
};
/* For the abort and shutdown ACK we must carry the init tag in the
* common header. Just the common header is all that is needed with a
* chunk descriptor.

1
include/net/sctp/sm.h
View File

@ -230,6 +230,7 @@ struct sctp_chunk *sctp_make_heartbeat_ack(const struct sctp_association *asoc,
const struct sctp_chunk *chunk,
const void *payload,
const size_t paylen);
struct sctp_chunk *sctp_make_pad(const struct sctp_association *asoc, int len);
struct sctp_chunk *sctp_make_op_error(const struct sctp_association *asoc,
const struct sctp_chunk *chunk,
__be16 cause_code, const void *payload,

26
net/sctp/sm_make_chunk.c
View File

@ -1218,6 +1218,32 @@ struct sctp_chunk *sctp_make_heartbeat_ack(const struct sctp_association *asoc,
return retval;
}
/* RFC4820 3. Padding Chunk (PAD)
* 0 1 2 3
* 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | Type = 0x84 | Flags=0 | Length |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | |
* \ Padding Data /
* / \
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
*/
struct sctp_chunk *sctp_make_pad(const struct sctp_association *asoc, int len)
{
struct sctp_chunk *retval;
retval = sctp_make_control(asoc, SCTP_CID_PAD, 0, len, GFP_ATOMIC);
if (!retval)
return NULL;
skb_put_zero(retval->skb, len);
retval->chunk_hdr->length = htons(ntohs(retval->chunk_hdr->length) + len);
retval->chunk_end = skb_tail_pointer(retval->skb);
return retval;
}
/* Create an Operation Error chunk with the specified space reserved.
* This routine can be used for containing multiple causes in the chunk.
*/

23
net/sctp/sm_statetable.c
View File

@ -526,6 +526,26 @@ auth_chunk_event_table[SCTP_NUM_AUTH_CHUNK_TYPES][SCTP_STATE_NUM_STATES] = {
TYPE_SCTP_AUTH,
}; /*state_fn_t auth_chunk_event_table[][] */
static const struct sctp_sm_table_entry
pad_chunk_event_table[SCTP_STATE_NUM_STATES] = {
/* SCTP_STATE_CLOSED */
TYPE_SCTP_FUNC(sctp_sf_discard_chunk),
/* SCTP_STATE_COOKIE_WAIT */
TYPE_SCTP_FUNC(sctp_sf_discard_chunk),
/* SCTP_STATE_COOKIE_ECHOED */
TYPE_SCTP_FUNC(sctp_sf_discard_chunk),
/* SCTP_STATE_ESTABLISHED */
TYPE_SCTP_FUNC(sctp_sf_discard_chunk),
/* SCTP_STATE_SHUTDOWN_PENDING */
TYPE_SCTP_FUNC(sctp_sf_discard_chunk),
/* SCTP_STATE_SHUTDOWN_SENT */
TYPE_SCTP_FUNC(sctp_sf_discard_chunk),
/* SCTP_STATE_SHUTDOWN_RECEIVED */
TYPE_SCTP_FUNC(sctp_sf_discard_chunk),
/* SCTP_STATE_SHUTDOWN_ACK_SENT */
TYPE_SCTP_FUNC(sctp_sf_discard_chunk),
}; /* chunk pad */
static const struct sctp_sm_table_entry
chunk_event_table_unknown[SCTP_STATE_NUM_STATES] = {
/* SCTP_STATE_CLOSED */
@ -992,6 +1012,9 @@ static const struct sctp_sm_table_entry *sctp_chunk_event_lookup(
case SCTP_CID_AUTH:
return &auth_chunk_event_table[0][state];
case SCTP_CID_PAD:
return &pad_chunk_event_table[state];
}
return &chunk_event_table_unknown[state];