Merge branch 'mptcp-pm-drop-tcp-ts-with-add_addrv6-port'

Matthieu Baerts says:

====================
mptcp: pm: drop TCP TS with ADD_ADDRv6 + port

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.
====================

Link: https://patch.msgid.link/20260605-net-next-mptcp-add-addr6-port-ts-v2-0-758e7ca73f4d@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

1 files changed, 3 insertions, 10 deletions

diff --git a/include/net/mptcp.h b/include/net/mptcp.h
index 24d1016a4664..71b9fc5a5796 100644
--- a/include/net/mptcp.h
+++ b/include/net/mptcp.h
@@ -72,7 +72,8 @@ struct mptcp_out_options {
 	u8 reset_reason:4,
 	   reset_transient:1,
 	   csum_reqd:1,
-	   allow_join_id0:1;
+	   allow_join_id0:1,
+	   drop_ts:1;
 	union {
 		struct {
 			u64 sndr_key;
@@ -153,7 +154,7 @@ bool mptcp_syn_options(struct sock *sk, const struct sk_buff *skb,
 bool mptcp_synack_options(const struct request_sock *req, unsigned int *size,
 			  struct mptcp_out_options *opts);
 int mptcp_established_options(struct sock *sk, struct sk_buff *skb,
-			      unsigned int remaining,
+			      unsigned int remaining, bool has_ts,
 			      struct mptcp_out_options *opts);
 bool mptcp_incoming_options(struct sock *sk, struct sk_buff *skb);
 
@@ -269,14 +270,6 @@ static inline bool mptcp_synack_options(const struct request_sock *req,
 	return false;
 }
 
-static inline int mptcp_established_options(struct sock *sk,
-					    struct sk_buff *skb,
-					    unsigned int remaining,
-					    struct mptcp_out_options *opts)
-{
-	return -1;
-}
-
 static inline bool mptcp_incoming_options(struct sock *sk,
 					  struct sk_buff *skb)
 {