netfilter: nf_conntrack: nf_conntrack snmp helper

[linux-2.6-microblaze.git] / net / netfilter / nf_conntrack_snmp.c

diff --git a/net/netfilter/nf_conntrack_snmp.c b/net/netfilter/nf_conntrack_snmp.c
new file mode 100644 (file)
index 0000000..6e545e2
--- /dev/null
+++ b/net/netfilter/nf_conntrack_snmp.c
@@ -0,0 +1,77 @@
+/*
+ *      SNMP service broadcast connection tracking helper
+ *
+ *      (c) 2011 Jiri Olsa <jolsa@redhat.com>
+ *
+ *      This program is free software; you can redistribute it and/or
+ *      modify it under the terms of the GNU General Public License
+ *      as published by the Free Software Foundation; either version
+ *      2 of the License, or (at your option) any later version.
+ */
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/in.h>
+
+#include <net/netfilter/nf_conntrack.h>
+#include <net/netfilter/nf_conntrack_helper.h>
+#include <net/netfilter/nf_conntrack_expect.h>
+
+#define SNMP_PORT      161
+
+MODULE_AUTHOR("Jiri Olsa <jolsa@redhat.com>");
+MODULE_DESCRIPTION("SNMP service broadcast connection tracking helper");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS_NFCT_HELPER("snmp");
+
+static unsigned int timeout __read_mostly = 30;
+module_param(timeout, uint, S_IRUSR);
+MODULE_PARM_DESC(timeout, "timeout for master connection/replies in seconds");
+
+int (*nf_nat_snmp_hook)(struct sk_buff *skb,
+                       unsigned int protoff,
+                       struct nf_conn *ct,
+                       enum ip_conntrack_info ctinfo);
+EXPORT_SYMBOL_GPL(nf_nat_snmp_hook);
+
+static int snmp_conntrack_help(struct sk_buff *skb, unsigned int protoff,
+               struct nf_conn *ct, enum ip_conntrack_info ctinfo)
+{
+       typeof(nf_nat_snmp_hook) nf_nat_snmp;
+
+       nf_conntrack_broadcast_help(skb, protoff, ct, ctinfo, timeout);
+
+       nf_nat_snmp = rcu_dereference(nf_nat_snmp_hook);
+       if (nf_nat_snmp && ct->status & IPS_NAT_MASK)
+               return nf_nat_snmp(skb, protoff, ct, ctinfo);
+
+       return NF_ACCEPT;
+}
+
+static struct nf_conntrack_expect_policy exp_policy = {
+       .max_expected   = 1,
+};
+
+static struct nf_conntrack_helper helper __read_mostly = {
+       .name                   = "snmp",
+       .tuple.src.l3num        = NFPROTO_IPV4,
+       .tuple.src.u.udp.port   = cpu_to_be16(SNMP_PORT),
+       .tuple.dst.protonum     = IPPROTO_UDP,
+       .me                     = THIS_MODULE,
+       .help                   = snmp_conntrack_help,
+       .expect_policy          = &exp_policy,
+};
+
+static int __init nf_conntrack_snmp_init(void)
+{
+       exp_policy.timeout = timeout;
+       return nf_conntrack_helper_register(&helper);
+}
+
+static void __exit nf_conntrack_snmp_fini(void)
+{
+       nf_conntrack_helper_unregister(&helper);
+}
+
+module_init(nf_conntrack_snmp_init);
+module_exit(nf_conntrack_snmp_fini);