On Tue, May 24, 2022 at 11:10:41AM -0700, Mat Martineau wrote: > [ Upstream commit ae66fb2ba6c3dcaf8b9612b65aa949a1a4bed150 ] > > RFC 8684 section 3.7 describes several opportunities for a MPTCP > connection to "fall back" to regular TCP early in the connection > process, before it has been confirmed that MPTCP options can be > successfully propagated on all SYN, SYN/ACK, and data packets. If a peer > acknowledges the first received data packet with a regular TCP header > (no MPTCP options), fallback is allowed. > > If the recipient of that first data packet finds a MPTCP DSS checksum > error, this provides an opportunity to fail gracefully with a TCP > fallback rather than resetting the connection (as might happen if a > checksum failure were detected later). > > This commit modifies the checksum failure code to attempt fallback on > the initial subflow of a MPTCP connection, only if it's a failure in the > first data mapping. In cases where the peer initiates the connection, > requests checksums, is the first to send data, and the peer is sending > incorrect checksums (see > https://github.com/multipath-tcp/mptcp_net-next/issues/275), this allows > the connection to proceed as TCP rather than reset. > > Cc: <stable@xxxxxxxxxxxxxxx> # 5.17.x > Cc: <stable@xxxxxxxxxxxxxxx> # 5.15.x > Fixes: dd8bcd1768ff ("mptcp: validate the data checksum") > Acked-by: Paolo Abeni <pabeni@xxxxxxxxxx> > Signed-off-by: Mat Martineau <mathew.j.martineau@xxxxxxxxxxxxxxx> > Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx> > [mathew.j.martineau: backport: Resolved bitfield conflict in protocol.h] > Signed-off-by: Mat Martineau <mathew.j.martineau@xxxxxxxxxxxxxxx> > --- > > This patch is already in 5.17.10-rc1 and 5.15.42-rc1, but involves a > context dependency on upstream commit 4cf86ae84c71 which I have > requested to be dropped from the stable queues. > > I'm posting this backport without the protocol.h conflict to > (hopefully?) make it easier for the stable maintainers to drop > 4cf86ae84c71. > > For context see https://lore.kernel.org/stable/fa953ec-288f-7715-c6fb-47a222e85270@xxxxxxxxxxxxxxx/ THanks, will take this after this round of releases. greg k-h
