[PATCH net-next 4/6] net: add sysctl for enabling RFC 8335 PROBE messages

[Andreas Roeseler <andreas.a.roeseler@gmail.com>]

Section 8 of RFC 8335 specifies potential security concerns of
responding to PROBE requests, and states that nodes that support PROBE
functionality MUST be able to enable/disable responses and it is
disabled by default. 

Add sysctl to enable responses to PROBE messages. 

Signed-off-by: Andreas Roeseler <andreas.a.roeseler@gmail.com>
---
 net/ipv4/sysctl_net_ipv4.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/net/ipv4/sysctl_net_ipv4.c b/net/ipv4/sysctl_net_ipv4.c
index 3e5f4f2e705e..f9f0e9d7394f 100644
--- a/net/ipv4/sysctl_net_ipv4.c
+++ b/net/ipv4/sysctl_net_ipv4.c
@@ -599,6 +599,13 @@ static struct ctl_table ipv4_net_table[] = {
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec
 	},
+	{
+		.procname	= "icmp_echo_enable_probe",
+		.data		= &init_net.ipv4.sysctl_icmp_echo_enable_probe,
+		.maxlen		= sizeof(int),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec
+	},
 	{
 		.procname	= "icmp_echo_ignore_broadcasts",
 		.data		= &init_net.ipv4.sysctl_icmp_echo_ignore_broadcasts,
-- 
2.25.1