SafeSysctlWhitelist: add net.ipv4.ping_group_range

sysctl value `net.ipv4.ping_group_range` can be used for allowing `ping`
command without `CAP_NET_RAW` capability.

e.g. `net.ipv4.ping_group_range="0 42"` to allow ping for users with
GID 0-GID 42.

This sysctl value was introduced in kernel 3.0 and has been namespaced
since its birth.

c319b4d76b (diff-5b536a7a92abed603bbb4caa61613270R57)

Signed-off-by: Akihiro Suda <akihiro.suda.cz@hco.ntt.co.jp>

pkg/security/podsecuritypolicy/sysctl/mustmatchpatterns.go

@@ -34,6 +34,7 @@ func SafeSysctlWhitelist() []string {
 		"kernel.shm_rmid_forced",
 		"net.ipv4.ip_local_port_range",
 		"net.ipv4.tcp_syncookies",
+		"net.ipv4.ping_group_range",
 	}
 }