Up to this series, it was possible to add a "signal" MPTCP endpoint with an IPv6 address and a port, or to directly request to send an ADD_ADDR with a v6 address and a port, but the expected ADD_ADDR wasn't sent when TCP timestamps was used for the connection.
In fact, such signalling option cannot be sent when TCP timestamps is used due to a lack of option space: the limit is at 40 bytes, and, with padding, TCP timestamps is taking 12 bytes, while an ADD_ADDR IPv6 + port is taking 30 bytes. The selected solution here is to simply drop the TCP timestamps option when such ADD_ADDR of 30 bytes needs to be sent. - Patches 1-3: small cleanups to avoid computing ADD/RM_ADDR twice. - Patches 4-7: the new feature, controlled by a new sysctl knob. - Patch 8: extra checks in the MPTCP Join selftests. - Patches 9-15: A bunch of refactoring: renamed confusing helpers and variables, and prevent future misused functions. Signed-off-by: Matthieu Baerts (NGI0) <[email protected]> --- Changes in v2: - Rebased: some diff caused by commit a02a765bd5c2 ("mptcp: change mptcp_established_options() to return opt_size") and commit bd34fa025726 ("mptcp: add-addr: always drop other suboptions") - Patch 4: Use READ_ONCE() to read sysctl data. (Eric) - Patches 5-6: Avoid passing local variables' addresses to mptcp_established_options not to force the compiler to use a stack canary in this hot function, even for non-MPTCP flows. (Eric) - Replaced previous patches 9-11 modifying selftests by a bunch of pm related refactoring: patches 9-15. - Link to v1: https://patch.msgid.link/20260601-net-next-mptcp-add-addr6-port-ts-v1-0-4fc25dfef...@kernel.org --- Matthieu Baerts (NGI0) (15): mptcp: options: suboptions sizes can be negative mptcp: pm: avoid computing rm_addr size twice mptcp: pm: avoid computing add_addr size twice mptcp: introduce add_addr_v6_port_drop_ts sysctl knob tcp: allow mptcp to drop TS for some packets mptcp: pm: drop TCP TS with ADD_ADDRv6 + port selftests: mptcp: validate ADD_ADDRv6 + TS + port selftests: mptcp: always check sent/dropped ADD_ADDRs mptcp: pm: use for_each_subflow helper mptcp: pm: rename add_entry structure to add_addr mptcp: pm: uniform announced addresses helpers mptcp: pm: remove add_ prefix from timer mptcp: pm: make mptcp_pm_add_addr_send_ack static mptcp: pm: avoid using del_timer directly mptcp: options: rst: drop unused skb parameter Documentation/networking/mptcp-sysctl.rst | 13 ++ include/net/mptcp.h | 13 +- net/ipv4/tcp_output.c | 10 +- net/mptcp/ctrl.c | 18 ++- net/mptcp/options.c | 68 +++------ net/mptcp/pm.c | 191 ++++++++++++++---------- net/mptcp/pm_kernel.c | 22 +-- net/mptcp/pm_userspace.c | 6 +- net/mptcp/protocol.h | 48 ++---- net/mptcp/subflow.c | 4 +- tools/testing/selftests/net/mptcp/mptcp_join.sh | 83 +++++----- 11 files changed, 248 insertions(+), 228 deletions(-) --- base-commit: bfa3d89cc15c09f7d1581c834a5ed725189ec19f change-id: 20260601-net-next-mptcp-add-addr6-port-ts-40d8d74d8e20 Best regards, -- Matthieu Baerts (NGI0) <[email protected]>
