From: Paolo Abeni <pabeni@xxxxxxxxxx>
[ Upstream commit dea2b1ea9c705c5ba351a9174403fd83dbb68fc3 ]
When some mapping related errors occurs we close the main
MPC subflow with a RST. We should instead fallback gracefully
to TCP, and do the reset only for MPJ subflows.
Fixes: d22f4988ffec ("mptcp: process MP_CAPABLE data option")
Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/192
Reported-by: Matthieu Baerts <matthieu.baerts@xxxxxxxxxxxx>
Signed-off-by: Paolo Abeni <pabeni@xxxxxxxxxx>
Signed-off-by: Mat Martineau <mathew.j.martineau@xxxxxxxxxxxxxxx>
Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
net/mptcp/subflow.c | 59 +++++++++++++++++++++++----------------------
1 file changed, 30 insertions(+), 29 deletions(-)
diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c
index 8878317b4386..8425cd393bf3 100644
--- a/net/mptcp/subflow.c
+++ b/net/mptcp/subflow.c
@@ -984,22 +984,11 @@ static bool subflow_check_data_avail(struct sock *ssk)
u64 old_ack;
status = get_mapping_status(ssk, msk);
- pr_debug("msk=%p ssk=%p status=%d", msk, ssk, status);
- if (status == MAPPING_INVALID) {
- ssk->sk_err = EBADMSG;
- goto fatal;
- }
- if (status == MAPPING_DUMMY) {
- __mptcp_do_fallback(msk);
- skb = skb_peek(&ssk->sk_receive_queue);
- subflow->map_valid = 1;
- subflow->map_seq = READ_ONCE(msk->ack_seq);
- subflow->map_data_len = skb->len;
- subflow->map_subflow_seq = tcp_sk(ssk)->copied_seq -
- subflow->ssn_offset;
- subflow->data_avail = MPTCP_SUBFLOW_DATA_AVAIL;
- return true;
- }
+ if (unlikely(status == MAPPING_INVALID))
+ goto fallback;
+
+ if (unlikely(status == MAPPING_DUMMY))
+ goto fallback;
if (status != MAPPING_OK)
goto no_data;
@@ -1012,10 +1001,8 @@ static bool subflow_check_data_avail(struct sock *ssk)
* MP_CAPABLE-based mapping
*/
if (unlikely(!READ_ONCE(msk->can_ack))) {
- if (!subflow->mpc_map) {
- ssk->sk_err = EBADMSG;
- goto fatal;
- }
+ if (!subflow->mpc_map)
+ goto fallback;
WRITE_ONCE(msk->remote_key, subflow->remote_key);
WRITE_ONCE(msk->ack_seq, subflow->map_seq);
WRITE_ONCE(msk->can_ack, true);
@@ -1043,15 +1030,29 @@ static bool subflow_check_data_avail(struct sock *ssk)
no_data:
subflow_sched_work_if_closed(msk, ssk);
return false;
-fatal:
- /* fatal protocol error, close the socket */
- /* This barrier is coupled with smp_rmb() in tcp_poll() */
- smp_wmb();
- ssk->sk_error_report(ssk);
- tcp_set_state(ssk, TCP_CLOSE);
- tcp_send_active_reset(ssk, GFP_ATOMIC);
- subflow->data_avail = 0;
- return false;
+
+fallback:
+ /* RFC 8684 section 3.7. */
+ if (subflow->mp_join || subflow->fully_established) {
+ /* fatal protocol error, close the socket.
+ * subflow_error_report() will introduce the appropriate barriers
+ */
+ ssk->sk_err = EBADMSG;
+ ssk->sk_error_report(ssk);
+ tcp_set_state(ssk, TCP_CLOSE);
+ tcp_send_active_reset(ssk, GFP_ATOMIC);
+ subflow->data_avail = 0;
+ return false;
+ }
+
+ __mptcp_do_fallback(msk);
+ skb = skb_peek(&ssk->sk_receive_queue);
+ subflow->map_valid = 1;
+ subflow->map_seq = READ_ONCE(msk->ack_seq);
+ subflow->map_data_len = skb->len;
+ subflow->map_subflow_seq = tcp_sk(ssk)->copied_seq - subflow->ssn_offset;
+ subflow->data_avail = MPTCP_SUBFLOW_DATA_AVAIL;
+ return true;
}
bool mptcp_subflow_data_available(struct sock *sk)
--
2.30.2
