Note that that additional client or server features are only
effective if the basic support (0x1 and 0x2) are enabled respectively.
+tcp_fastopen_blackhole_timeout_sec - INTEGER
+ Initial time period in second to disable Fastopen on active TCP sockets
+ when a TFO firewall blackhole issue happens.
+ This time period will grow exponentially when more blackhole issues
+ get detected right after Fastopen is re-enabled and will reset to
+ initial value when the blackhole issue goes away.
+ By default, it is set to 1hr.
+
tcp_syn_retries - INTEGER
Number of times initial SYNs for an active TCP connection attempt
will be retransmitted. Should not be higher than 127. Default value
u8 syn_data:1, /* SYN includes data */
syn_fastopen:1, /* SYN includes Fast Open option */
syn_fastopen_exp:1,/* SYN includes Fast Open exp. option */
+ syn_fastopen_ch:1, /* Active TFO re-enabling probe */
syn_data_acked:1,/* data in SYN is acked by SYN-ACK */
save_syn:1, /* Save headers of SYN packet */
is_cwnd_limited:1;/* forward progress limited by snd_cwnd? */
struct rcu_head rcu;
};
+extern unsigned int sysctl_tcp_fastopen_blackhole_timeout;
+void tcp_fastopen_active_disable(void);
+bool tcp_fastopen_active_should_disable(struct sock *sk);
+void tcp_fastopen_active_disable_ofo_check(struct sock *sk);
+void tcp_fastopen_active_timeout_reset(void);
+
/* Latencies incurred by various limits for a sender. They are
* chronograph-like stats that are mutually exclusive.
*/
return ret;
}
+static int proc_tfo_blackhole_detect_timeout(struct ctl_table *table,
+ int write,
+ void __user *buffer,
+ size_t *lenp, loff_t *ppos)
+{
+ int ret;
+
+ ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
+ if (write && ret == 0)
+ tcp_fastopen_active_timeout_reset();
+ return ret;
+}
+
static struct ctl_table ipv4_table[] = {
{
.procname = "tcp_timestamps",
.maxlen = ((TCP_FASTOPEN_KEY_LENGTH * 2) + 10),
.proc_handler = proc_tcp_fastopen_key,
},
+ {
+ .procname = "tcp_fastopen_blackhole_timeout_sec",
+ .data = &sysctl_tcp_fastopen_blackhole_timeout,
+ .maxlen = sizeof(int),
+ .mode = 0644,
+ .proc_handler = proc_tfo_blackhole_detect_timeout,
+ .extra1 = &zero,
+ },
{
.procname = "tcp_abort_on_overflow",
.data = &sysctl_tcp_abort_on_overflow,
tcp_clear_xmit_timers(sk);
__skb_queue_purge(&sk->sk_receive_queue);
tcp_write_queue_purge(sk);
+ tcp_fastopen_active_disable_ofo_check(sk);
skb_rbtree_purge(&tp->out_of_order_queue);
inet->inet_dport = 0;
cookie->len = -1;
return false;
}
+
+ /* Firewall blackhole issue check */
+ if (tcp_fastopen_active_should_disable(sk)) {
+ cookie->len = -1;
+ return false;
+ }
+
if (sysctl_tcp_fastopen & TFO_CLIENT_NO_COOKIE) {
cookie->len = -1;
return true;
return false;
}
EXPORT_SYMBOL(tcp_fastopen_defer_connect);
+
+/*
+ * The following code block is to deal with middle box issues with TFO:
+ * Middlebox firewall issues can potentially cause server's data being
+ * blackholed after a successful 3WHS using TFO.
+ * The proposed solution is to disable active TFO globally under the
+ * following circumstances:
+ * 1. client side TFO socket receives out of order FIN
+ * 2. client side TFO socket receives out of order RST
+ * We disable active side TFO globally for 1hr at first. Then if it
+ * happens again, we disable it for 2h, then 4h, 8h, ...
+ * And we reset the timeout back to 1hr when we see a successful active
+ * TFO connection with data exchanges.
+ */
+
+/* Default to 1hr */
+unsigned int sysctl_tcp_fastopen_blackhole_timeout __read_mostly = 60 * 60;
+static atomic_t tfo_active_disable_times __read_mostly = ATOMIC_INIT(0);
+static unsigned long tfo_active_disable_stamp __read_mostly;
+
+/* Disable active TFO and record current jiffies and
+ * tfo_active_disable_times
+ */
+void tcp_fastopen_active_disable(void)
+{
+ atomic_inc(&tfo_active_disable_times);
+ tfo_active_disable_stamp = jiffies;
+}
+
+/* Reset tfo_active_disable_times to 0 */
+void tcp_fastopen_active_timeout_reset(void)
+{
+ atomic_set(&tfo_active_disable_times, 0);
+}
+
+/* Calculate timeout for tfo active disable
+ * Return true if we are still in the active TFO disable period
+ * Return false if timeout already expired and we should use active TFO
+ */
+bool tcp_fastopen_active_should_disable(struct sock *sk)
+{
+ int tfo_da_times = atomic_read(&tfo_active_disable_times);
+ int multiplier;
+ unsigned long timeout;
+
+ if (!tfo_da_times)
+ return false;
+
+ /* Limit timout to max: 2^6 * initial timeout */
+ multiplier = 1 << min(tfo_da_times - 1, 6);
+ timeout = multiplier * sysctl_tcp_fastopen_blackhole_timeout * HZ;
+ if (time_before(jiffies, tfo_active_disable_stamp + timeout))
+ return true;
+
+ /* Mark check bit so we can check for successful active TFO
+ * condition and reset tfo_active_disable_times
+ */
+ tcp_sk(sk)->syn_fastopen_ch = 1;
+ return false;
+}
+
+/* Disable active TFO if FIN is the only packet in the ofo queue
+ * and no data is received.
+ * Also check if we can reset tfo_active_disable_times if data is
+ * received successfully on a marked active TFO sockets opened on
+ * a non-loopback interface
+ */
+void tcp_fastopen_active_disable_ofo_check(struct sock *sk)
+{
+ struct tcp_sock *tp = tcp_sk(sk);
+ struct rb_node *p;
+ struct sk_buff *skb;
+ struct dst_entry *dst;
+
+ if (!tp->syn_fastopen)
+ return;
+
+ if (!tp->data_segs_in) {
+ p = rb_first(&tp->out_of_order_queue);
+ if (p && !rb_next(p)) {
+ skb = rb_entry(p, struct sk_buff, rbnode);
+ if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN) {
+ tcp_fastopen_active_disable();
+ return;
+ }
+ }
+ } else if (tp->syn_fastopen_ch &&
+ atomic_read(&tfo_active_disable_times)) {
+ dst = sk_dst_get(sk);
+ if (!(dst && dst->dev && (dst->dev->flags & IFF_LOOPBACK)))
+ tcp_fastopen_active_timeout_reset();
+ dst_release(dst);
+ }
+}
if (rst_seq_match)
tcp_reset(sk);
- else
+ else {
+ /* Disable TFO if RST is out-of-order
+ * and no data has been received
+ * for current active TFO socket
+ */
+ if (tp->syn_fastopen && !tp->data_segs_in &&
+ sk->sk_state == TCP_ESTABLISHED)
+ tcp_fastopen_active_disable();
tcp_send_challenge_ack(sk, skb);
+ }
goto discard;
}
break;
}
- if (tp->linger2 < 0 ||
- (TCP_SKB_CB(skb)->end_seq != TCP_SKB_CB(skb)->seq &&
- after(TCP_SKB_CB(skb)->end_seq - th->fin, tp->rcv_nxt))) {
+ if (tp->linger2 < 0) {
+ tcp_done(sk);
+ NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPABORTONDATA);
+ return 1;
+ }
+ if (TCP_SKB_CB(skb)->end_seq != TCP_SKB_CB(skb)->seq &&
+ after(TCP_SKB_CB(skb)->end_seq - th->fin, tp->rcv_nxt)) {
+ /* Receive out of order FIN after close() */
+ if (tp->syn_fastopen && th->fin)
+ tcp_fastopen_active_disable();
tcp_done(sk);
NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPABORTONDATA);
return 1;
/* Cleanup up the write buffer. */
tcp_write_queue_purge(sk);
+ /* Check if we want to disable active TFO */
+ tcp_fastopen_active_disable_ofo_check(sk);
+
/* Cleans up our, hopefully empty, out_of_order_queue. */
skb_rbtree_purge(&tp->out_of_order_queue);
git.samba.org / sfrench / cifs-2.6.git / commitdiff