[NETFILTER]: nf_conntrack: add NetBIOS name service helper port
Add nf_conntrack port of the NetBIOS name service conntrack helper.
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/netfilter/Kconfig b/net/netfilter/Kconfig
index bd50897..d1a365d 100644
--- a/net/netfilter/Kconfig
+++ b/net/netfilter/Kconfig
@@ -194,6 +194,25 @@
To compile it as a module, choose M here. If unsure, say N.
+config NF_CONNTRACK_NETBIOS_NS
+ tristate "NetBIOS name service protocol support (EXPERIMENTAL)"
+ depends on EXPERIMENTAL && NF_CONNTRACK
+ help
+ NetBIOS name service requests are sent as broadcast messages from an
+ unprivileged port and responded to with unicast messages to the
+ same port. This make them hard to firewall properly because connection
+ tracking doesn't deal with broadcasts. This helper tracks locally
+ originating NetBIOS name service requests and the corresponding
+ responses. It relies on correct IP address configuration, specifically
+ netmask and broadcast address. When properly configured, the output
+ of "ip address show" should look similar to this:
+
+ $ ip -4 address show eth0
+ 4: eth0: <BROADCAST,MULTICAST,UP> mtu 1500 qdisc pfifo_fast qlen 1000
+ inet 172.16.2.252/24 brd 172.16.2.255 scope global eth0
+
+ To compile it as a module, choose M here. If unsure, say N.
+
config NF_CT_NETLINK
tristate 'Connection tracking netlink interface (EXPERIMENTAL)'
depends on EXPERIMENTAL && NF_CONNTRACK && NETFILTER_NETLINK
diff --git a/net/netfilter/Makefile b/net/netfilter/Makefile
index 343fd48..67144b2 100644
--- a/net/netfilter/Makefile
+++ b/net/netfilter/Makefile
@@ -26,6 +26,7 @@
obj-$(CONFIG_NF_CONNTRACK_FTP) += nf_conntrack_ftp.o
obj-$(CONFIG_NF_CONNTRACK_H323) += nf_conntrack_h323.o
obj-$(CONFIG_NF_CONNTRACK_IRC) += nf_conntrack_irc.o
+obj-$(CONFIG_NF_CONNTRACK_NETBIOS_NS) += nf_conntrack_netbios_ns.o
# generic X tables
obj-$(CONFIG_NETFILTER_XTABLES) += x_tables.o xt_tcpudp.o
diff --git a/net/netfilter/nf_conntrack_netbios_ns.c b/net/netfilter/nf_conntrack_netbios_ns.c
new file mode 100644
index 0000000..4fad3ad
--- /dev/null
+++ b/net/netfilter/nf_conntrack_netbios_ns.c
@@ -0,0 +1,125 @@
+/*
+ * NetBIOS name service broadcast connection tracking helper
+ *
+ * (c) 2005 Patrick McHardy <kaber@trash.net>
+ *
+ * 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.
+ */
+/*
+ * This helper tracks locally originating NetBIOS name service
+ * requests by issuing permanent expectations (valid until
+ * timing out) matching all reply connections from the
+ * destination network. The only NetBIOS specific thing is
+ * actually the port number.
+ */
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/skbuff.h>
+#include <linux/netdevice.h>
+#include <linux/inetdevice.h>
+#include <linux/if_addr.h>
+#include <linux/in.h>
+#include <linux/ip.h>
+#include <net/route.h>
+
+#include <net/netfilter/nf_conntrack.h>
+#include <net/netfilter/nf_conntrack_helper.h>
+#include <net/netfilter/nf_conntrack_expect.h>
+
+#define NMBD_PORT 137
+
+MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
+MODULE_DESCRIPTION("NetBIOS name service broadcast connection tracking helper");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("ip_conntrack_netbios_ns");
+
+static unsigned int timeout __read_mostly = 3;
+module_param(timeout, uint, 0400);
+MODULE_PARM_DESC(timeout, "timeout for master connection/replies in seconds");
+
+static int help(struct sk_buff **pskb, unsigned int protoff,
+ struct nf_conn *ct, enum ip_conntrack_info ctinfo)
+{
+ struct nf_conntrack_expect *exp;
+ struct iphdr *iph = (*pskb)->nh.iph;
+ struct rtable *rt = (struct rtable *)(*pskb)->dst;
+ struct in_device *in_dev;
+ __be32 mask = 0;
+
+ /* we're only interested in locally generated packets */
+ if ((*pskb)->sk == NULL)
+ goto out;
+ if (rt == NULL || !(rt->rt_flags & RTCF_BROADCAST))
+ goto out;
+ if (CTINFO2DIR(ctinfo) != IP_CT_DIR_ORIGINAL)
+ goto out;
+
+ rcu_read_lock();
+ in_dev = __in_dev_get_rcu(rt->u.dst.dev);
+ if (in_dev != NULL) {
+ for_primary_ifa(in_dev) {
+ if (ifa->ifa_broadcast == iph->daddr) {
+ mask = ifa->ifa_mask;
+ break;
+ }
+ } endfor_ifa(in_dev);
+ }
+ rcu_read_unlock();
+
+ if (mask == 0)
+ goto out;
+
+ exp = nf_conntrack_expect_alloc(ct);
+ if (exp == NULL)
+ goto out;
+
+ exp->tuple = ct->tuplehash[IP_CT_DIR_REPLY].tuple;
+ exp->tuple.src.u.udp.port = htons(NMBD_PORT);
+
+ exp->mask.src.u3.ip = mask;
+ exp->mask.src.u.udp.port = htons(0xFFFF);
+ exp->mask.dst.u3.ip = htonl(0xFFFFFFFF);
+ exp->mask.dst.u.udp.port = htons(0xFFFF);
+ exp->mask.dst.protonum = 0xFF;
+
+ exp->expectfn = NULL;
+ exp->flags = NF_CT_EXPECT_PERMANENT;
+
+ nf_conntrack_expect_related(exp);
+ nf_conntrack_expect_put(exp);
+
+ nf_ct_refresh(ct, *pskb, timeout * HZ);
+out:
+ return NF_ACCEPT;
+}
+
+static struct nf_conntrack_helper helper __read_mostly = {
+ .name = "netbios-ns",
+ .tuple.src.l3num = AF_INET,
+ .tuple.src.u.udp.port = __constant_htons(NMBD_PORT),
+ .tuple.dst.protonum = IPPROTO_UDP,
+ .mask.src.l3num = 0xFFFF,
+ .mask.src.u.udp.port = __constant_htons(0xFFFF),
+ .mask.dst.protonum = 0xFF,
+ .max_expected = 1,
+ .me = THIS_MODULE,
+ .help = help,
+};
+
+static int __init nf_conntrack_netbios_ns_init(void)
+{
+ helper.timeout = timeout;
+ return nf_conntrack_helper_register(&helper);
+}
+
+static void __exit nf_conntrack_netbios_ns_fini(void)
+{
+ nf_conntrack_helper_unregister(&helper);
+}
+
+module_init(nf_conntrack_netbios_ns_init);
+module_exit(nf_conntrack_netbios_ns_fini);