linux/net/mptcp
Mat Martineau ae66fb2ba6 mptcp: Do TCP fallback on early DSS checksum failure
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.

Fixes: dd8bcd1768 ("mptcp: validate the data checksum")
Acked-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2022-05-18 13:05:42 +01:00
..
crypto_test.c mptcp: move crypto test to KUNIT 2020-06-26 16:21:39 -07:00
crypto.c kunit: mptcp: adhere to KUNIT formatting standard 2021-04-16 17:10:40 -07:00
ctrl.c mptcp: faster active backup recovery 2021-08-14 11:37:25 +01:00
diag.c mptcp: allow dumping subflow context to userspace 2020-03-29 22:14:48 -07:00
Kconfig kunit: mptcp: adhere to KUNIT formatting standard 2021-04-16 17:10:40 -07:00
Makefile kunit: mptcp: adhere to KUNIT formatting standard 2021-04-16 17:10:40 -07:00
mib.c mptcp: add the mibs for MP_RST 2022-03-04 21:54:30 -08:00
mib.h mptcp: add the mibs for MP_RST 2022-03-04 21:54:30 -08:00
mptcp_diag.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2021-09-30 14:49:21 -07:00
options.c mptcp: fix checksum byte order 2022-05-18 13:05:42 +01:00
pm_netlink.c mptcp: send ADD_ADDR echo before create subflows 2022-03-18 14:14:09 -07:00
pm.c mptcp: fix subflow accounting on close 2022-05-13 17:04:30 -07:00
protocol.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2022-03-23 10:53:49 -07:00
protocol.h mptcp: Do TCP fallback on early DSS checksum failure 2022-05-18 13:05:42 +01:00
sockopt.c mptcp: add SNDTIMEO setsockopt support 2022-02-16 20:52:03 -08:00
subflow.c mptcp: Do TCP fallback on early DSS checksum failure 2022-05-18 13:05:42 +01:00
syncookies.c mptcp: don't return sockets in foreign netns 2021-09-24 10:51:36 +01:00
token_test.c mptcp: don't return sockets in foreign netns 2021-09-24 10:51:36 +01:00
token.c mptcp: full disconnect implementation 2022-01-07 11:27:06 +00:00