netdev - [PATCH V3 net-next 3/5] net: add sysctl for enabling RFC 8335 PROBE messages

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Date:   Wed, 17 Feb 2021 10:08:09 -0800
From:   Andreas Roeseler <andreas.a.roeseler@...il.com>
To:     davem@...emloft.net
Cc:     yoshfuji@...ux-ipv6.org, dsahern@...nel.org, kuba@...nel.org,
        netdev@...r.kernel.org
Subject: [PATCH V3 net-next 3/5] net: add sysctl for enabling RFC 8335 PROBE messages

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@...il.com>
---
Changes since v1:
 - Combine patches related to sysctl into one patch

Changes since v2:
Suggested by Willem de Brujin <willemdebrujin.kernel@...il.com>
 - Use proc_dointvec_minmax with zero and one
---
 include/net/netns/ipv4.h   | 1 +
 net/ipv4/sysctl_net_ipv4.c | 9 +++++++++
 2 files changed, 10 insertions(+)

diff --git a/include/net/netns/ipv4.h b/include/net/netns/ipv4.h
index 70a2a085dd1a..362388ab40c8 100644
--- a/include/net/netns/ipv4.h
+++ b/include/net/netns/ipv4.h
@@ -85,6 +85,7 @@ struct netns_ipv4 {
 #endif
 
 	int sysctl_icmp_echo_ignore_all;
+	int sysctl_icmp_echo_enable_probe;
 	int sysctl_icmp_echo_ignore_broadcasts;
 	int sysctl_icmp_ignore_bogus_error_responses;
 	int sysctl_icmp_ratelimit;
diff --git a/net/ipv4/sysctl_net_ipv4.c b/net/ipv4/sysctl_net_ipv4.c
index f55095d3ed16..fec3f142d8c9 100644
--- a/net/ipv4/sysctl_net_ipv4.c
+++ b/net/ipv4/sysctl_net_ipv4.c
@@ -599,6 +599,15 @@ 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_minmax,
+		.extra1		= SYSCTL_ZERO,
+		.extra2		= SYSCTL_ONE
+	},
 	{
 		.procname	= "icmp_echo_ignore_broadcasts",
 		.data		= &init_net.ipv4.sysctl_icmp_echo_ignore_broadcasts,
-- 
2.25.1