Patch "Namespaceify mtu_expires sysctl" has been added to the 5.15-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    Namespaceify mtu_expires sysctl

to the 5.15-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     namespaceify-mtu_expires-sysctl.patch
and it can be found in the queue-5.15 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 263bf32bee3c8ef0e309b7b0ef3285ddeec1b7dd
Author: xu xin <xu.xin16@xxxxxxxxxx>
Date:   Tue Jan 4 10:59:47 2022 +0000

    Namespaceify mtu_expires sysctl
    
    [ Upstream commit 1135fad204805518462c1f0caaca6bcd52ba78cf ]
    
    This patch enables the sysctl mtu_expires to be configured per net
    namespace.
    
    Signed-off-by: xu xin <xu.xin16@xxxxxxxxxx>
    Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
    Stable-dep-of: 139512191bd0 ("ipv4: use RCU protection in __ip_rt_update_pmtu()")
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/include/net/netns/ipv4.h b/include/net/netns/ipv4.h
index 16515c04a46a7..8bc0d865338e4 100644
--- a/include/net/netns/ipv4.h
+++ b/include/net/netns/ipv4.h
@@ -85,6 +85,7 @@ struct netns_ipv4 {
 	int sysctl_icmp_ratemask;
 
 	u32 ip_rt_min_pmtu;
+	int ip_rt_mtu_expires;
 
 	struct local_ports ip_local_ports;
 
diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index 9a837cd2b925a..75c379315ef37 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -119,6 +119,7 @@
 #define RT_GC_TIMEOUT (300*HZ)
 
 #define DEFAULT_MIN_PMTU (512 + 20 + 20)
+#define DEFAULT_MTU_EXPIRES (10 * 60 * HZ)
 
 static int ip_rt_max_size;
 static int ip_rt_redirect_number __read_mostly	= 9;
@@ -126,7 +127,6 @@ static int ip_rt_redirect_load __read_mostly	= HZ / 50;
 static int ip_rt_redirect_silence __read_mostly	= ((HZ / 50) << (9 + 1));
 static int ip_rt_error_cost __read_mostly	= HZ;
 static int ip_rt_error_burst __read_mostly	= 5 * HZ;
-static int ip_rt_mtu_expires __read_mostly	= 10 * 60 * HZ;
 static int ip_rt_min_advmss __read_mostly	= 256;
 
 static int ip_rt_gc_timeout __read_mostly	= RT_GC_TIMEOUT;
@@ -1041,7 +1041,7 @@ static void __ip_rt_update_pmtu(struct rtable *rt, struct flowi4 *fl4, u32 mtu)
 	}
 
 	if (rt->rt_pmtu == mtu && !lock &&
-	    time_before(jiffies, dst->expires - ip_rt_mtu_expires / 2))
+	    time_before(jiffies, dst->expires - net->ipv4.ip_rt_mtu_expires / 2))
 		return;
 
 	rcu_read_lock();
@@ -1051,7 +1051,7 @@ static void __ip_rt_update_pmtu(struct rtable *rt, struct flowi4 *fl4, u32 mtu)
 		fib_select_path(net, &res, fl4, NULL);
 		nhc = FIB_RES_NHC(res);
 		update_or_create_fnhe(nhc, fl4->daddr, 0, mtu, lock,
-				      jiffies + ip_rt_mtu_expires);
+				      jiffies + net->ipv4.ip_rt_mtu_expires);
 	}
 	rcu_read_unlock();
 }
@@ -3572,13 +3572,6 @@ static struct ctl_table ipv4_route_table[] = {
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec,
 	},
-	{
-		.procname	= "mtu_expires",
-		.data		= &ip_rt_mtu_expires,
-		.maxlen		= sizeof(int),
-		.mode		= 0644,
-		.proc_handler	= proc_dointvec_jiffies,
-	},
 	{
 		.procname	= "min_adv_mss",
 		.data		= &ip_rt_min_advmss,
@@ -3606,6 +3599,13 @@ static struct ctl_table ipv4_route_netns_table[] = {
 		.proc_handler   = proc_dointvec_minmax,
 		.extra1         = &ip_min_valid_pmtu,
 	},
+	{
+		.procname       = "mtu_expires",
+		.data           = &init_net.ipv4.ip_rt_mtu_expires,
+		.maxlen         = sizeof(int),
+		.mode           = 0644,
+		.proc_handler   = proc_dointvec_jiffies,
+	},
 	{ },
 };
 
@@ -3667,6 +3667,7 @@ static __net_init int netns_ip_rt_init(struct net *net)
 {
 	/* Set default value for namespaceified sysctls */
 	net->ipv4.ip_rt_min_pmtu = DEFAULT_MIN_PMTU;
+	net->ipv4.ip_rt_mtu_expires = DEFAULT_MTU_EXPIRES;
 	return 0;
 }