tree a0705feab8186cf08dcf0e53ecb57d521bae601e
parent 2248bcfcd8fb622ec88b8587d0c1f139635ffd2e
author Patrick McHardy <[EMAIL PROTECTED]> Wed, 07 Sep 2005 05:08:51 -0700
committer David S. Miller <[EMAIL PROTECTED]> Wed, 07 Sep 2005 05:08:51 -0700
[NETFILTER]: Add NetBIOS name service helper
Signed-off-by: Patrick McHardy <[EMAIL PROTECTED]>
Signed-off-by: David S. Miller <[EMAIL PROTECTED]>
net/ipv4/netfilter/Kconfig | 19 +++
net/ipv4/netfilter/Makefile | 1
net/ipv4/netfilter/ip_conntrack_netbios_ns.c | 131 +++++++++++++++++++++++++++
3 files changed, 151 insertions(+)
diff --git a/net/ipv4/netfilter/Kconfig b/net/ipv4/netfilter/Kconfig
--- a/net/ipv4/netfilter/Kconfig
+++ b/net/ipv4/netfilter/Kconfig
@@ -85,6 +85,25 @@ config IP_NF_IRC
To compile it as a module, choose M here. If unsure, say Y.
+config IP_NF_NETBIOS_NS
+ tristate "NetBIOS name service protocol support (EXPERIMENTAL)"
+ depends on IP_NF_CONNTRACK && EXPERIMENTAL
+ 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 IP_NF_TFTP
tristate "TFTP protocol support"
depends on IP_NF_CONNTRACK
diff --git a/net/ipv4/netfilter/Makefile b/net/ipv4/netfilter/Makefile
--- a/net/ipv4/netfilter/Makefile
+++ b/net/ipv4/netfilter/Makefile
@@ -21,6 +21,7 @@ obj-$(CONFIG_IP_NF_AMANDA) += ip_conntra
obj-$(CONFIG_IP_NF_TFTP) += ip_conntrack_tftp.o
obj-$(CONFIG_IP_NF_FTP) += ip_conntrack_ftp.o
obj-$(CONFIG_IP_NF_IRC) += ip_conntrack_irc.o
+obj-$(CONFIG_IP_NF_NETBIOS_NS) += ip_conntrack_netbios_ns.o
# NAT helpers
obj-$(CONFIG_IP_NF_NAT_AMANDA) += ip_nat_amanda.o
diff --git a/net/ipv4/netfilter/ip_conntrack_netbios_ns.c
b/net/ipv4/netfilter/ip_conntrack_netbios_ns.c
new file mode 100644
--- /dev/null
+++ b/net/ipv4/netfilter/ip_conntrack_netbios_ns.c
@@ -0,0 +1,131 @@
+/*
+ * NetBIOS name service broadcast connection tracking helper
+ *
+ * (c) 2005 Patrick McHardy <[EMAIL PROTECTED]>
+ *
+ * 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/in.h>
+#include <linux/ip.h>
+#include <linux/udp.h>
+#include <net/route.h>
+
+#include <linux/netfilter.h>
+#include <linux/netfilter_ipv4.h>
+#include <linux/netfilter_ipv4/ip_conntrack.h>
+#include <linux/netfilter_ipv4/ip_conntrack_helper.h>
+
+MODULE_AUTHOR("Patrick McHardy <[EMAIL PROTECTED]>");
+MODULE_DESCRIPTION("NetBIOS name service broadcast connection tracking
helper");
+MODULE_LICENSE("GPL");
+
+static unsigned int timeout = 3;
+module_param(timeout, int, 0600);
+MODULE_PARM_DESC(timeout, "timeout for master connection/replies in seconds");
+
+static int help(struct sk_buff **pskb,
+ struct ip_conntrack *ct, enum ip_conntrack_info ctinfo)
+{
+ struct ip_conntrack_expect *exp;
+ struct iphdr *iph = (*pskb)->nh.iph;
+ struct udphdr _uh, *uh;
+ struct rtable *rt = (struct rtable *)(*pskb)->dst;
+ struct in_device *in_dev;
+ u_int32_t 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(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;
+
+ uh = skb_header_pointer(*pskb, iph->ihl * 4, sizeof(_uh), &_uh);
+ BUG_ON(uh == NULL);
+
+ exp = ip_conntrack_expect_alloc(ct);
+ if (exp == NULL)
+ goto out;
+ memset(&exp->tuple, 0, sizeof(exp->tuple));
+ exp->tuple.src.ip = iph->daddr & mask;
+ exp->tuple.dst.ip = iph->saddr;
+ exp->tuple.dst.u.udp.port = uh->source;
+ exp->tuple.dst.protonum = IPPROTO_UDP;
+
+ memset(&exp->mask, 0, sizeof(exp->mask));
+ exp->mask.src.ip = mask;
+ exp->mask.dst.ip = 0xFFFFFFFF;
+ exp->mask.dst.u.udp.port = 0xFFFF;
+ exp->mask.dst.protonum = 0xFF;
+
+ exp->expectfn = NULL;
+ exp->flags = IP_CT_EXPECT_PERMANENT;
+
+ ip_conntrack_expect_related(exp);
+ ip_conntrack_expect_put(exp);
+
+ ip_ct_refresh_acct(ct, ctinfo, NULL, timeout * HZ);
+out:
+ return NF_ACCEPT;
+}
+
+static struct ip_conntrack_helper helper = {
+ .name = "netbios-ns",
+ .tuple = {
+ .src.u.udp.port = __constant_htons(137),
+ .dst.protonum = IPPROTO_UDP,
+ },
+ .mask = {
+ .src.u.udp.port = 0xFFFF,
+ .dst.protonum = 0xFF,
+ },
+ .max_expected = 1,
+ .me = THIS_MODULE,
+ .help = help,
+};
+
+static int __init init(void)
+{
+ helper.timeout = timeout;
+ return ip_conntrack_helper_register(&helper);
+}
+
+static void __exit fini(void)
+{
+ ip_conntrack_helper_unregister(&helper);
+}
+
+module_init(init);
+module_exit(fini);
-
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