From c0ffc38d6cb431c96dfd7aa549efa9fe18c46b1d Mon Sep 17 00:00:00 2001 From: Shardul Bankar Date: Fri, 1 May 2026 21:35:34 +0200 Subject: [PATCH] mptcp: use MPJoinSynAckHMacFailure for SynAck HMAC failure commit c4a99a921949cddc590b22bb14eeb23dffcc3ba6 upstream. In subflow_finish_connect(), HMAC validation of the server's HMAC in SYN/ACK + MP_JOIN increments MPTCP_MIB_JOINACKMAC ("HMAC was wrong on ACK + MP_JOIN") on failure. The function processes the SYN/ACK, not the ACK; the matching MPTCP_MIB_JOINSYNACKMAC counter ("HMAC was wrong on SYN/ACK + MP_JOIN") exists but is not incremented anywhere in the tree. The mirror site on the server, subflow_syn_recv_sock(), already uses JOINACKMAC correctly for ACK HMAC failure. Use JOINSYNACKMAC at the SYN/ACK validation site so each counter reflects the packet whose HMAC actually failed. Suggested-by: Matthieu Baerts (NGI0) Fixes: fc518953bc9c ("mptcp: add and use MIB counter infrastructure") Cc: stable@vger.kernel.org Signed-off-by: Shardul Bankar Reviewed-by: Matthieu Baerts (NGI0) Signed-off-by: Matthieu Baerts (NGI0) Link: https://patch.msgid.link/20260501-net-mptcp-misc-fixes-7-1-rc3-v1-1-b70118df778e@kernel.org Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman --- net/mptcp/subflow.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c index 784ffd08c15a..446a1c4ae5e9 100644 --- a/net/mptcp/subflow.c +++ b/net/mptcp/subflow.c @@ -460,7 +460,7 @@ static void subflow_finish_connect(struct sock *sk, const struct sk_buff *skb) subflow->backup); if (!subflow_thmac_valid(subflow)) { - MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_JOINACKMAC); + MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_JOINSYNACKMAC); subflow->reset_reason = MPTCP_RST_EMPTCP; goto do_reset; }