tcp: consolidate paws check
Wow, it was quite tricky to merge that stream of negations but I think I finally got it right: check & replace_ts_recent: (s32)(rcv_tsval - ts_recent) >= 0 => 0 (s32)(ts_recent - rcv_tsval) <= 0 => 0 discard: (s32)(ts_recent - rcv_tsval) > TCP_PAWS_WINDOW => 1 (s32)(ts_recent - rcv_tsval) <= TCP_PAWS_WINDOW => 0 I toggled the return values of tcp_paws_check around since the old encoding added yet-another negation making tracking of truth-values really complicated. Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi> Signed-off-by: David S. Miller <davem@davemloft.net>
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c43d558a51
Коммит
c887e6d2d9
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@ -997,11 +997,21 @@ static inline int tcp_fin_time(const struct sock *sk)
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return fin_timeout;
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}
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static inline int tcp_paws_check(const struct tcp_options_received *rx_opt, int rst)
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static inline int tcp_paws_check(const struct tcp_options_received *rx_opt,
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int paws_win)
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{
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if ((s32)(rx_opt->rcv_tsval - rx_opt->ts_recent) >= 0)
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return 0;
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if (get_seconds() >= rx_opt->ts_recent_stamp + TCP_PAWS_24DAYS)
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if ((s32)(rx_opt->ts_recent - rx_opt->rcv_tsval) <= paws_win)
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return 1;
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if (unlikely(get_seconds() >= rx_opt->ts_recent_stamp + TCP_PAWS_24DAYS))
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return 1;
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return 0;
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}
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static inline int tcp_paws_reject(const struct tcp_options_received *rx_opt,
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int rst)
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{
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if (tcp_paws_check(rx_opt, 0))
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return 0;
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/* RST segments are not recommended to carry timestamp,
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@ -3883,8 +3883,7 @@ static inline void tcp_replace_ts_recent(struct tcp_sock *tp, u32 seq)
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* Not only, also it occurs for expired timestamps.
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*/
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if ((s32)(tp->rx_opt.rcv_tsval - tp->rx_opt.ts_recent) >= 0 ||
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get_seconds() >= tp->rx_opt.ts_recent_stamp + TCP_PAWS_24DAYS)
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if (tcp_paws_check(&tp->rx_opt, 0))
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tcp_store_ts_recent(tp);
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}
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}
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@ -3936,9 +3935,9 @@ static inline int tcp_paws_discard(const struct sock *sk,
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const struct sk_buff *skb)
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{
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const struct tcp_sock *tp = tcp_sk(sk);
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return ((s32)(tp->rx_opt.ts_recent - tp->rx_opt.rcv_tsval) > TCP_PAWS_WINDOW &&
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get_seconds() < tp->rx_opt.ts_recent_stamp + TCP_PAWS_24DAYS &&
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!tcp_disordered_ack(sk, skb));
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return !tcp_paws_check(&tp->rx_opt, TCP_PAWS_WINDOW) &&
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!tcp_disordered_ack(sk, skb);
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}
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/* Check segment sequence number for validity.
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@ -5513,7 +5512,7 @@ discard:
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/* PAWS check. */
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if (tp->rx_opt.ts_recent_stamp && tp->rx_opt.saw_tstamp &&
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tcp_paws_check(&tp->rx_opt, 0))
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tcp_paws_reject(&tp->rx_opt, 0))
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goto discard_and_undo;
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if (th->syn) {
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@ -107,7 +107,7 @@ tcp_timewait_state_process(struct inet_timewait_sock *tw, struct sk_buff *skb,
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if (tmp_opt.saw_tstamp) {
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tmp_opt.ts_recent = tcptw->tw_ts_recent;
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tmp_opt.ts_recent_stamp = tcptw->tw_ts_recent_stamp;
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paws_reject = tcp_paws_check(&tmp_opt, th->rst);
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paws_reject = tcp_paws_reject(&tmp_opt, th->rst);
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}
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}
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@ -511,7 +511,7 @@ struct sock *tcp_check_req(struct sock *sk, struct sk_buff *skb,
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* from another data.
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*/
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tmp_opt.ts_recent_stamp = get_seconds() - ((TCP_TIMEOUT_INIT/HZ)<<req->retrans);
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paws_reject = tcp_paws_check(&tmp_opt, th->rst);
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paws_reject = tcp_paws_reject(&tmp_opt, th->rst);
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}
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}
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