net: add limits to ip_default_ttl

ip_default_ttl should be between 1 and 255

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 5 insertions, 2 deletions

diff --git a/net/ipv4/sysctl_net_ipv4.c b/net/ipv4/sysctl_net_ipv4.c
index e85ff593060..1a456652086 100644
--- a/net/ipv4/sysctl_net_ipv4.c
+++ b/net/ipv4/sysctl_net_ipv4.c
@@ -28,6 +28,8 @@ static int ip_local_port_range_min[] = { 1, 1 };
 static int ip_local_port_range_max[] = { 65535, 65535 };
 static int tcp_adv_win_scale_min = -31;
 static int tcp_adv_win_scale_max = 31;
+static int ip_ttl_min = 1;
+static int ip_ttl_max = 255;
 
 /* Update system visible IP port range */
 static void set_local_port_range(int range[2])
@@ -155,8 +157,9 @@ static struct ctl_table ipv4_table[] = {
                 .data           = &sysctl_ip_default_ttl,
                 .maxlen         = sizeof(int),
                 .mode           = 0644,
-                .proc_handler   = proc_dointvec,
-                .extra2         = &init_net,
+                .proc_handler   = proc_dointvec_minmax,
+                .extra1         = &ip_ttl_min,
+                .extra2         = &ip_ttl_max,
         },
         {
                 .procname       = "ip_no_pmtu_disc",