kernel.git/net/mptcp/fastopen.c, branch linux-6.4.y

mptcp: fix NULL pointer dereference on fastopen early fallback

2023-04-13T16:58:55Z

In case of early fallback to TCP, subflow_syn_recv_sock() deletes the subflow context before returning the newly allocated sock to the caller. The fastopen path does not cope with the above unconditionally dereferencing the subflow context. Fixes: 36b122baf6a8 ("mptcp: add subflow_v(4,6)_send_synack()") Cc: stable@vger.kernel.org Signed-off-by: Paolo Abeni Reviewed-by: Matthieu Baerts Signed-off-by: Matthieu Baerts Signed-off-by: Jakub Kicinski

mptcp: add subflow_v(4,6)_send_synack()

2022-11-30T04:24:25Z

The send_synack() needs to be overridden for MPTCP to support TFO for two reasons: - There is not be enough space in the TCP options if the TFO cookie has to be added in the SYN+ACK with other options: MSS (4), SACK OK (2), Timestamps (10), Window Scale (3+1), TFO (10+2), MP_CAPABLE (12). MPTCPv1 specs -- RFC 8684, section B.1 [1] -- suggest to drop the TCP timestamps option in this case. - The data received in the SYN has to be handled: the SKB can be dequeued from the subflow sk and transferred to the MPTCP sk. Counters need to be updated accordingly and the application can be notified at the end because some bytes have been received. [1] https://www.rfc-editor.org/rfc/rfc8684.html#section-b.1 Co-developed-by: Paolo Abeni Signed-off-by: Paolo Abeni Co-developed-by: Matthieu Baerts Signed-off-by: Matthieu Baerts Signed-off-by: Dmytro Shytyi Signed-off-by: Matthieu Baerts Signed-off-by: Jakub Kicinski

mptcp: implement delayed seq generation for passive fastopen

2022-11-30T04:24:25Z

With fastopen in place, the first subflow socket is created before the MPC handshake completes, and we need to properly initialize the sequence numbers at MPC ACK reception. Co-developed-by: Paolo Abeni Signed-off-by: Paolo Abeni Co-developed-by: Matthieu Baerts Signed-off-by: Matthieu Baerts Signed-off-by: Dmytro Shytyi Signed-off-by: Matthieu Baerts Signed-off-by: Jakub Kicinski