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mptcp: use "middlebox interference" for MP_TCPRST in case map_valid i…
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…s false

RFC8684 suggests use of "Middlebox interference (code 0x06)" in case of
MPJ subflow that carries data at TCP level with no DSS sub-option. This
is generally the case when mpext is NULL or mpext->use_map is 0: use a
dedicated value of 'mapping_status' and use it before closing the socket
in subflow_check_data_avail().

Link: multipath-tcp/mptcp_net-next#518 (comment)
Signed-off-by: Davide Caratti <[email protected]>
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dcaratti authored and intel-lab-lkp committed Oct 8, 2024
1 parent 8837df5 commit 5b65635
Showing 1 changed file with 11 additions and 4 deletions.
15 changes: 11 additions & 4 deletions net/mptcp/subflow.c
Original file line number Diff line number Diff line change
Expand Up @@ -960,7 +960,8 @@ enum mapping_status {
MAPPING_EMPTY,
MAPPING_DATA_FIN,
MAPPING_DUMMY,
MAPPING_BAD_CSUM
MAPPING_BAD_CSUM,
MAPPING_NODSS
};

static void dbg_bad_map(struct mptcp_subflow_context *subflow, u32 ssn)
Expand Down Expand Up @@ -1118,7 +1119,7 @@ static enum mapping_status get_mapping_status(struct sock *ssk,
}

if (!subflow->map_valid)
return MAPPING_INVALID;
return MAPPING_NODSS;

goto validate_seq;
}
Expand Down Expand Up @@ -1332,7 +1333,7 @@ static bool subflow_check_data_avail(struct sock *ssk)
status = get_mapping_status(ssk, msk);
trace_subflow_check_data_avail(status, skb_peek(&ssk->sk_receive_queue));
if (unlikely(status == MAPPING_INVALID || status == MAPPING_DUMMY ||
status == MAPPING_BAD_CSUM))
status == MAPPING_BAD_CSUM || status == MAPPING_NODSS))
goto fallback;

if (status != MAPPING_OK)
Expand Down Expand Up @@ -1385,7 +1386,13 @@ static bool subflow_check_data_avail(struct sock *ssk)
* subflow_error_report() will introduce the appropriate barriers
*/
subflow->reset_transient = 0;
subflow->reset_reason = MPTCP_RST_EMPTCP;
switch (status) {
case MAPPING_NODSS:
subflow->reset_reason = MPTCP_RST_EMIDDLEBOX;
break;
default:
subflow->reset_reason = MPTCP_RST_EMPTCP;
}

reset:
WRITE_ONCE(ssk->sk_err, EBADMSG);
Expand Down

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