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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>
This commit is contained in:
Haishuang Yan 2017-09-27 11:35:43 +08:00 committed by David S. Miller
parent 4371384856
commit 3733be14a3
4 changed files with 27 additions and 28 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
include/net/netns/ipv4.h
View File

@ -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;

20
net/ipv4/sysctl_net_ipv4.c
View File

@ -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;
}
@ -397,14 +399,6 @@ static struct ctl_table ipv4_table[] = {
.mode = 0644,
.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,
@ -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",

30
net/ipv4/tcp_fastopen.c
View File

@ -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);
}
}

2
net/ipv4/tcp_ipv4.c
View File

@ -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: