building larger TSO frames.
Default: 3
-tcp_tw_reuse - BOOLEAN
- Allow to reuse TIME-WAIT sockets for new connections when it is
- safe from protocol viewpoint. Default value is 0.
+tcp_tw_reuse - INTEGER
+ Enable reuse of TIME-WAIT sockets for new connections when it is
+ safe from protocol viewpoint.
+ 0 - disable
+ 1 - global enable
+ 2 - enable for loopback traffic only
It should not be changed without advice/request of technical
experts.
+ Default: 2
tcp_window_scaling - BOOLEAN
Enable window scaling as defined in RFC1323.
static int zero;
static int one = 1;
+static int two = 2;
static int four = 4;
static int thousand = 1000;
static int gso_max_segs = GSO_MAX_SEGS;
.data = &init_net.ipv4.sysctl_tcp_tw_reuse,
.maxlen = sizeof(int),
.mode = 0644,
- .proc_handler = proc_dointvec
+ .proc_handler = proc_dointvec_minmax,
+ .extra1 = &zero,
+ .extra2 = &two,
},
{
.procname = "tcp_max_tw_buckets",
int tcp_twsk_unique(struct sock *sk, struct sock *sktw, void *twp)
{
+ const struct inet_timewait_sock *tw = inet_twsk(sktw);
const struct tcp_timewait_sock *tcptw = tcp_twsk(sktw);
struct tcp_sock *tp = tcp_sk(sk);
+ int reuse = sock_net(sk)->ipv4.sysctl_tcp_tw_reuse;
+
+ if (reuse == 2) {
+ /* Still does not detect *everything* that goes through
+ * lo, since we require a loopback src or dst address
+ * or direct binding to 'lo' interface.
+ */
+ bool loopback = false;
+ if (tw->tw_bound_dev_if == LOOPBACK_IFINDEX)
+ loopback = true;
+#if IS_ENABLED(CONFIG_IPV6)
+ if (tw->tw_family == AF_INET6) {
+ if (ipv6_addr_loopback(&tw->tw_v6_daddr) ||
+ (ipv6_addr_v4mapped(&tw->tw_v6_daddr) &&
+ (tw->tw_v6_daddr.s6_addr[12] == 127)) ||
+ ipv6_addr_loopback(&tw->tw_v6_rcv_saddr) ||
+ (ipv6_addr_v4mapped(&tw->tw_v6_rcv_saddr) &&
+ (tw->tw_v6_rcv_saddr.s6_addr[12] == 127)))
+ loopback = true;
+ } else
+#endif
+ {
+ if (ipv4_is_loopback(tw->tw_daddr) ||
+ ipv4_is_loopback(tw->tw_rcv_saddr))
+ loopback = true;
+ }
+ if (!loopback)
+ reuse = 0;
+ }
/* With PAWS, it is safe from the viewpoint
of data integrity. Even without PAWS it is safe provided sequence
and use initial timestamp retrieved from peer table.
*/
if (tcptw->tw_ts_recent_stamp &&
- (!twp || (sock_net(sk)->ipv4.sysctl_tcp_tw_reuse &&
- get_seconds() - tcptw->tw_ts_recent_stamp > 1))) {
+ (!twp || (reuse && get_seconds() - tcptw->tw_ts_recent_stamp > 1))) {
tp->write_seq = tcptw->tw_snd_nxt + 65535 + 2;
if (tp->write_seq == 0)
tp->write_seq = 1;
net->ipv4.sysctl_tcp_orphan_retries = 0;
net->ipv4.sysctl_tcp_fin_timeout = TCP_FIN_TIMEOUT;
net->ipv4.sysctl_tcp_notsent_lowat = UINT_MAX;
- net->ipv4.sysctl_tcp_tw_reuse = 0;
+ net->ipv4.sysctl_tcp_tw_reuse = 2;
cnt = tcp_hashinfo.ehash_mask + 1;
net->ipv4.tcp_death_row.sysctl_max_tw_buckets = (cnt + 1) / 2;