From c83a47e50d8fd3825a4758158e9edd5acdc74185 Mon Sep 17 00:00:00 2001 From: Florian Westphal Date: Thu, 30 Jul 2020 21:25:54 +0200 Subject: mptcp: subflow: add mptcp_subflow_init_cookie_req helper Will be used to initialize the mptcp request socket when a MP_CAPABLE request was handled in syncookie mode, i.e. when a TCP ACK containing a MP_CAPABLE option is a valid syncookie value. Normally (non-cookie case), MPTCP will generate a unique 32 bit connection ID and stores it in the MPTCP token storage to be able to retrieve the mptcp socket for subflow joining. In syncookie case, we do not want to store any state, so just generate the unique ID and use it in the reply. This means there is a small window where another connection could generate the same token. When Cookie ACK comes back, we check that the token has not been registered in the mean time. If it was, the connection needs to fall back to TCP. Changes in v2: - use req->syncookie instead of passing 'want_cookie' arg to ->init_req() (Eric Dumazet) Signed-off-by: Florian Westphal Reviewed-by: Mat Martineau Signed-off-by: David S. Miller --- include/net/mptcp.h | 10 ++++++++++ 1 file changed, 10 insertions(+) (limited to 'include') diff --git a/include/net/mptcp.h b/include/net/mptcp.h index 76eb915bf91c..3525d2822abe 100644 --- a/include/net/mptcp.h +++ b/include/net/mptcp.h @@ -131,6 +131,9 @@ static inline bool mptcp_skb_can_collapse(const struct sk_buff *to, } void mptcp_seq_show(struct seq_file *seq); +int mptcp_subflow_init_cookie_req(struct request_sock *req, + const struct sock *sk_listener, + struct sk_buff *skb); #else static inline void mptcp_init(void) @@ -200,6 +203,13 @@ static inline bool mptcp_skb_can_collapse(const struct sk_buff *to, static inline void mptcp_space(const struct sock *ssk, int *s, int *fs) { } static inline void mptcp_seq_show(struct seq_file *seq) { } + +static inline int mptcp_subflow_init_cookie_req(struct request_sock *req, + const struct sock *sk_listener, + struct sk_buff *skb) +{ + return 0; /* TCP fallback */ +} #endif /* CONFIG_MPTCP */ #if IS_ENABLED(CONFIG_MPTCP_IPV6) -- cgit v1.2.3