!909 [sync] PR-907: tcp/dccp: Add another way to allocate local ports in connect()

Merge Pull Request from: @openeuler-sync-bot 
 

Origin pull request: 
https://gitee.com/openeuler/kernel/pulls/907 
 
PR sync from: Liu Jian liujian56@huawei.com https://mailweb.openeuler.org/hyperkitty/list/kernel@openeuler.org/thread/BSVWS6P3YEQUKJMVM2L3BMIPHWVKODOD/ 
 
Link:https://gitee.com/openeuler/kernel/pulls/909 

Reviewed-by: Yue Haibing <yuehaibing@huawei.com> 
Reviewed-by: Jialin Zhang <zhangjialin11@huawei.com> 
Signed-off-by: Jialin Zhang <zhangjialin11@huawei.com> 

include/net/tcp.h

@@ -258,6 +258,7 @@ extern long sysctl_tcp_mem[3];
 extern atomic_long_t tcp_memory_allocated;
 extern struct percpu_counter tcp_sockets_allocated;
 extern unsigned long tcp_memory_pressure;
+extern int sysctl_local_port_allocation;
 
 /* optimized version of sk_under_memory_pressure() for TCP sockets */
 static inline bool tcp_under_memory_pressure(const struct sock *sk)

net/ipv4/inet_hashtables.c

@@ -742,7 +742,7 @@ int __inet_hash_connect(struct inet_timewait_death_row *death_row,
 	struct net *net = sock_net(sk);
 	struct inet_bind_bucket *tb;
 	u32 remaining, offset;
-	int ret, i, low, high;
+	int ret, i, low, high, span_size;
 	int l3mdev;
 	u32 index;
 
@@ -762,6 +762,11 @@ int __inet_hash_connect(struct inet_timewait_death_row *death_row,
 		local_bh_enable();
 		return ret;
 	}
+	/* local_port_allocation 0 means even and odd port allocation strategy
+	 * will be applied, so span size is 2; otherwise sequential allocation
+	 * will be used and span size is 1. Default value is 0.
+	 */
+	span_size = sysctl_local_port_allocation ? 1 : 2;
 
 	l3mdev = inet_sk_bound_l3mdev(sk);
 
@@ -783,7 +788,7 @@ int __inet_hash_connect(struct inet_timewait_death_row *death_row,
 	offset &= ~1U;
 other_parity_scan:
 	port = low + offset;
-	for (i = 0; i < remaining; i += 2, port += 2) {
+	for (i = 0; i < remaining; i += span_size, port += span_size) {
 		if (unlikely(port >= high))
 			port -= remaining;
 		if (inet_is_local_reserved_port(net, port))
@@ -824,7 +829,7 @@ int __inet_hash_connect(struct inet_timewait_death_row *death_row,
 	}
 
 	offset++;
-	if ((offset & 1) && remaining > 1)
+	if ((offset & 1) && remaining > 1 && span_size == 2)
 		goto other_parity_scan;
 
 	return -EADDRNOTAVAIL;

net/ipv4/sysctl_net_ipv4.c

@@ -51,6 +51,7 @@ static int comp_sack_nr_max = 255;
 static u32 u32_max_div_HZ = UINT_MAX / HZ;
 static int one_day_secs = 24 * 3600;
 
+int sysctl_local_port_allocation;
 /* obsolete */
 static int sysctl_tcp_low_latency __read_mostly;
 
@@ -575,6 +576,13 @@ static struct ctl_table ipv4_table[] = {
 		.extra2		= SYSCTL_ONE,
 	},
 #endif
+	{
+		.procname	= "local_port_allocation",
+		.data		= &sysctl_local_port_allocation,
+		.maxlen		= sizeof(int),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec,
+	},
 	{ }
 };