zones: drop outgoing invalid traffic in masqueraded zones

[project/firewall3.git] / zones.c

diff --git a/zones.c b/zones.c
index 520d00c..26f6215 100644 (file)
--- a/zones.c
+++ b/zones.c
@@ -66,6 +66,7 @@ const struct fw3_option fw3_zone_opts[] = {
        FW3_OPT("output",              target,   zone,     policy_output),
 
        FW3_OPT("masq",                bool,     zone,     masq),
+       FW3_OPT("masq_allow_invalid",  bool,     zone,     masq_allow_invalid),
        FW3_LIST("masq_src",           network,  zone,     masq_src),
        FW3_LIST("masq_dest",          network,  zone,     masq_dest),
 
@@ -354,6 +355,17 @@ print_interface_rule(struct fw3_ipt_handle *handle, struct fw3_state *state,
 
                        if (has(zone->flags, handle->family, t))
                        {
+                               if (t == FW3_FLAG_ACCEPT &&
+                                   zone->masq && !zone->masq_allow_invalid)
+                               {
+                                       r = fw3_ipt_rule_create(handle, NULL, NULL, dev, NULL, sub);
+                                       fw3_ipt_rule_extra(r, "-m conntrack --ctstate INVALID");
+                                       fw3_ipt_rule_comment(r, "Prevent NAT leakage");
+                                       fw3_ipt_rule_target(r, fw3_flag_names[FW3_FLAG_DROP]);
+                                       fw3_ipt_rule_replace(r, "zone_%s_dest_%s", zone->name,
+                                                            fw3_flag_names[t]);
+                               }
+
                                r = fw3_ipt_rule_create(handle, NULL, NULL, dev, NULL, sub);
                                fw3_ipt_rule_target(r, jump_target(t));
                                fw3_ipt_rule_extra(r, zone->extra_dest);