Re: [PATCH V2 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 <redacted>
---
Changes since v1:
 - Combine patches related to sysctl into one patch
---
 include/net/netns/ipv4.h   | 1 +
 net/ipv4/sysctl_net_ipv4.c | 7 +++++++
 2 files changed, 8 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 e5798b3b59d2..06b7241bc01d 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
+       },