ipv4: Namespaceify tcp_fastopen_blackhole_timeout knob

Different namespace application might require different time period in
second to disable Fastopen on active TCP sockets.

Tested:
Simulate following similar situation that the server's data gets dropped
after 3WHS.
C ---- syn-data ---> S
C <--- syn/ack ----- S
C ---- ack --------> S
S (accept & write)
C?  X <- data ------ S
	[retry and timeout]

And then print netstat of TCPFastOpenBlackhole, the counter increased as
expected when the firewall blackhole issue is detected and active TFO is
disabled.
# cat /proc/net/netstat | awk '{print $91}'
TCPFastOpenBlackhole
1

Signed-off-by: Haishuang Yan <yanhaishuang@cmss.chinamobile.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/net/netns/ipv4.h b/include/net/netns/ipv4.h
index 7bb9603..2c4222a 100644 (file)
--- a/include/net/netns/ipv4.h
+++ b/include/net/netns/ipv4.h
@@ -133,6 +133,9 @@ struct netns_ipv4 {
        int sysctl_tcp_fastopen;
        struct tcp_fastopen_context __rcu *tcp_fastopen_ctx;
        spinlock_t tcp_fastopen_ctx_lock;
+       unsigned int sysctl_tcp_fastopen_blackhole_timeout;
+       atomic_t tfo_active_disable_times;
+       unsigned long tfo_active_disable_stamp;
 
 #ifdef CONFIG_NET_L3_MASTER_DEV
        int sysctl_udp_l3mdev_accept;

diff --git a/net/ipv4/sysctl_net_ipv4.c b/net/ipv4/sysctl_net_ipv4.c
index 20e19fe..cac8dd3 100644 (file)
--- a/net/ipv4/sysctl_net_ipv4.c
+++ b/net/ipv4/sysctl_net_ipv4.c
@@ -355,11 +355,13 @@ static int proc_tfo_blackhole_detect_timeout(struct ctl_table *table,
                                             void __user *buffer,
                                             size_t *lenp, loff_t *ppos)
 {
+       struct net *net = container_of(table->data, struct net,
+           ipv4.sysctl_tcp_fastopen_blackhole_timeout);
        int ret;
 
        ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
        if (write && ret == 0)
-               tcp_fastopen_active_timeout_reset();
+               atomic_set(&net->ipv4.tfo_active_disable_times, 0);
 
        return ret;
 }
@@ -398,14 +400,6 @@ static struct ctl_table ipv4_table[] = {
                .proc_handler   = proc_dointvec
        },
        {
-               .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,
                .maxlen         = sizeof(int),
@@ -1083,6 +1077,14 @@ static struct ctl_table ipv4_net_table[] = {
                .maxlen         = ((TCP_FASTOPEN_KEY_LENGTH * 2) + 10),
                .proc_handler   = proc_tcp_fastopen_key,
        },
+       {
+               .procname       = "tcp_fastopen_blackhole_timeout_sec",
+               .data           = &init_net.ipv4.sysctl_tcp_fastopen_blackhole_timeout,
+               .maxlen         = sizeof(int),
+               .mode           = 0644,
+               .proc_handler   = proc_tfo_blackhole_detect_timeout,
+               .extra1         = &zero,
+       },
 #ifdef CONFIG_IP_ROUTE_MULTIPATH
        {
                .procname       = "fib_multipath_use_neigh",

diff --git a/net/ipv4/tcp_fastopen.c b/net/ipv4/tcp_fastopen.c
index 4eae44a..de470e7 100644 (file)
--- a/net/ipv4/tcp_fastopen.c
+++ b/net/ipv4/tcp_fastopen.c
@@ -422,25 +422,16 @@ EXPORT_SYMBOL(tcp_fastopen_defer_connect);
  * 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(struct sock *sk)
 {
-       atomic_inc(&tfo_active_disable_times);
-       tfo_active_disable_stamp = jiffies;
-       NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPFASTOPENBLACKHOLE);
-}
+       struct net *net = sock_net(sk);
 
-/* Reset tfo_active_disable_times to 0 */
-void tcp_fastopen_active_timeout_reset(void)
-{
-       atomic_set(&tfo_active_disable_times, 0);
+       atomic_inc(&net->ipv4.tfo_active_disable_times);
+       net->ipv4.tfo_active_disable_stamp = jiffies;
+       NET_INC_STATS(net, LINUX_MIB_TCPFASTOPENBLACKHOLE);
 }
 
 /* Calculate timeout for tfo active disable
@@ -449,17 +440,18 @@ void tcp_fastopen_active_timeout_reset(void)
  */
 bool tcp_fastopen_active_should_disable(struct sock *sk)
 {
-       int tfo_da_times = atomic_read(&tfo_active_disable_times);
-       int multiplier;
+       unsigned int tfo_bh_timeout = sock_net(sk)->ipv4.sysctl_tcp_fastopen_blackhole_timeout;
+       int tfo_da_times = atomic_read(&sock_net(sk)->ipv4.tfo_active_disable_times);
        unsigned long timeout;
+       int multiplier;
 
        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))
+       timeout = multiplier * tfo_bh_timeout * HZ;
+       if (time_before(jiffies, sock_net(sk)->ipv4.tfo_active_disable_stamp + timeout))
                return true;
 
        /* Mark check bit so we can check for successful active TFO
@@ -495,10 +487,10 @@ void tcp_fastopen_active_disable_ofo_check(struct sock *sk)
                        }
                }
        } else if (tp->syn_fastopen_ch &&
-                  atomic_read(&tfo_active_disable_times)) {
+                  atomic_read(&sock_net(sk)->ipv4.tfo_active_disable_times)) {
                dst = sk_dst_get(sk);
                if (!(dst && dst->dev && (dst->dev->flags & IFF_LOOPBACK)))
-                       tcp_fastopen_active_timeout_reset();
+                       atomic_set(&sock_net(sk)->ipv4.tfo_active_disable_times, 0);
                dst_release(dst);
        }
 }

diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 49c74c0..ad3b5bb 100644 (file)
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -2474,6 +2474,8 @@ static int __net_init tcp_sk_init(struct net *net)
 
        net->ipv4.sysctl_tcp_fastopen = TFO_CLIENT_ENABLE;
        spin_lock_init(&net->ipv4.tcp_fastopen_ctx_lock);
+       net->ipv4.sysctl_tcp_fastopen_blackhole_timeout = 60 * 60;
+       atomic_set(&net->ipv4.tfo_active_disable_times, 0);
 
        return 0;
 fail: