new file mode 100644
@@ -0,0 +1,9 @@
+#ifndef _NF_CONNTRACK_SNMP_H
+#define _NF_CONNTRACK_SNMP_H
+
+extern int (*nf_nat_snmp_hook)(struct sk_buff *skb,
+ unsigned int protoff,
+ struct nf_conn *ct,
+ enum ip_conntrack_info ctinfo);
+
+#endif /* _NF_CONNTRACK_SNMP_H */
@@ -63,4 +63,10 @@ static inline struct nf_conn_help *nfct_help(const struct nf_conn *ct)
extern int nf_conntrack_helper_init(void);
extern void nf_conntrack_helper_fini(void);
+extern int nf_conntrack_broadcast_help(struct sk_buff *skb,
+ unsigned int protoff,
+ struct nf_conn *ct,
+ enum ip_conntrack_info ctinfo,
+ unsigned int timeout);
+
#endif /*_NF_CONNTRACK_HELPER_H*/
@@ -206,8 +206,9 @@ config IP_NF_TARGET_REDIRECT
config NF_NAT_SNMP_BASIC
tristate "Basic SNMP-ALG support"
- depends on NF_NAT
+ depends on NF_CONNTRACK_SNMP && NF_NAT
depends on NETFILTER_ADVANCED
+ default NF_NAT && NF_CONNTRACK_SNMP
---help---
This module implements an Application Layer Gateway (ALG) for
@@ -54,6 +54,7 @@
#include <net/netfilter/nf_conntrack_expect.h>
#include <net/netfilter/nf_conntrack_helper.h>
#include <net/netfilter/nf_nat_helper.h>
+#include <linux/netfilter/nf_conntrack_snmp.h>
MODULE_LICENSE("GPL");
MODULE_AUTHOR("James Morris <jmorris@intercode.com.au>");
@@ -1310,9 +1311,9 @@ static int __init nf_nat_snmp_basic_init(void)
{
int ret = 0;
- ret = nf_conntrack_helper_register(&snmp_helper);
- if (ret < 0)
- return ret;
+ BUG_ON(nf_nat_snmp_hook != NULL);
+ rcu_assign_pointer(nf_nat_snmp_hook, help);
+
ret = nf_conntrack_helper_register(&snmp_trap_helper);
if (ret < 0) {
nf_conntrack_helper_unregister(&snmp_helper);
@@ -1323,7 +1324,7 @@ static int __init nf_nat_snmp_basic_init(void)
static void __exit nf_nat_snmp_basic_fini(void)
{
- nf_conntrack_helper_unregister(&snmp_helper);
+ rcu_assign_pointer(nf_nat_snmp_hook, NULL);
nf_conntrack_helper_unregister(&snmp_trap_helper);
}
@@ -185,9 +185,13 @@ config NF_CONNTRACK_IRC
To compile it as a module, choose M here. If unsure, say N.
+config NF_CONNTRACK_BROADCAST
+ tristate
+
config NF_CONNTRACK_NETBIOS_NS
tristate "NetBIOS name service protocol support"
depends on NETFILTER_ADVANCED
+ select NF_CONNTRACK_BROADCAST
help
NetBIOS name service requests are sent as broadcast messages from an
unprivileged port and responded to with unicast messages to the
@@ -204,6 +208,21 @@ config NF_CONNTRACK_NETBIOS_NS
To compile it as a module, choose M here. If unsure, say N.
+config NF_CONNTRACK_SNMP
+ tristate "SNMP service protocol support"
+ depends on NETFILTER_ADVANCED
+ select NF_CONNTRACK_BROADCAST
+ help
+ SNMP 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 SNMP service requests and the corresponding
+ responses. It relies on correct IP address configuration, specifically
+ netmask and broadcast address.
+
+ To compile it as a module, choose M here. If unsure, say N.
+
config NF_CONNTRACK_PPTP
tristate "PPtP protocol support"
depends on NETFILTER_ADVANCED
@@ -28,7 +28,9 @@ obj-$(CONFIG_NF_CONNTRACK_AMANDA) += nf_conntrack_amanda.o
obj-$(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-$(CONFIG_NF_CONNTRACK_BROADCAST) += nf_conntrack_broadcast.o
obj-$(CONFIG_NF_CONNTRACK_NETBIOS_NS) += nf_conntrack_netbios_ns.o
+obj-$(CONFIG_NF_CONNTRACK_SNMP) += nf_conntrack_snmp.o
obj-$(CONFIG_NF_CONNTRACK_PPTP) += nf_conntrack_pptp.o
obj-$(CONFIG_NF_CONNTRACK_SANE) += nf_conntrack_sane.o
obj-$(CONFIG_NF_CONNTRACK_SIP) += nf_conntrack_sip.o
new file mode 100644
@@ -0,0 +1,82 @@
+/*
+ * 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.
+ */
+
+#include <linux/module.h>
+#include <linux/ip.h>
+#include <net/route.h>
+#include <linux/inetdevice.h>
+#include <linux/skbuff.h>
+
+#include <net/netfilter/nf_conntrack.h>
+#include <net/netfilter/nf_conntrack_helper.h>
+#include <net/netfilter/nf_conntrack_expect.h>
+
+int nf_conntrack_broadcast_help(struct sk_buff *skb,
+ unsigned int protoff,
+ struct nf_conn *ct,
+ enum ip_conntrack_info ctinfo,
+ unsigned int timeout)
+{
+ struct nf_conntrack_expect *exp;
+ struct iphdr *iph = ip_hdr(skb);
+ struct rtable *rt = skb_rtable(skb);
+ struct in_device *in_dev;
+ struct nf_conn_help *help = nfct_help(ct);
+ __be32 mask = 0;
+
+ /* we're only interested in locally generated packets */
+ if (skb->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->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_ct_expect_alloc(ct);
+ if (exp == NULL)
+ goto out;
+
+ exp->tuple = ct->tuplehash[IP_CT_DIR_REPLY].tuple;
+ exp->tuple.src.u.udp.port = help->helper->tuple.src.u.udp.port;
+
+ exp->mask.src.u3.ip = mask;
+ exp->mask.src.u.udp.port = htons(0xFFFF);
+
+ exp->expectfn = NULL;
+ exp->flags = NF_CT_EXPECT_PERMANENT;
+ exp->class = NF_CT_EXPECT_CLASS_DEFAULT;
+ exp->helper = NULL;
+
+ nf_ct_expect_related(exp);
+ nf_ct_expect_put(exp);
+
+ nf_ct_refresh(ct, skb, timeout * HZ);
+out:
+ return NF_ACCEPT;
+}
+EXPORT_SYMBOL_GPL(nf_conntrack_broadcast_help);
+
+MODULE_LICENSE("GPL");
@@ -18,14 +18,7 @@
#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 <linux/netfilter.h>
-#include <net/route.h>
#include <net/netfilter/nf_conntrack.h>
#include <net/netfilter/nf_conntrack_helper.h>
@@ -40,75 +33,26 @@ MODULE_ALIAS("ip_conntrack_netbios_ns");
MODULE_ALIAS_NFCT_HELPER("netbios_ns");
static unsigned int timeout __read_mostly = 3;
-module_param(timeout, uint, 0400);
+module_param(timeout, uint, S_IRUSR);
MODULE_PARM_DESC(timeout, "timeout for master connection/replies in seconds");
-static int help(struct sk_buff *skb, unsigned int protoff,
- struct nf_conn *ct, enum ip_conntrack_info ctinfo)
-{
- struct nf_conntrack_expect *exp;
- struct iphdr *iph = ip_hdr(skb);
- struct rtable *rt = skb_rtable(skb);
- struct in_device *in_dev;
- __be32 mask = 0;
-
- /* we're only interested in locally generated packets */
- if (skb->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->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_ct_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->expectfn = NULL;
- exp->flags = NF_CT_EXPECT_PERMANENT;
- exp->class = NF_CT_EXPECT_CLASS_DEFAULT;
- exp->helper = NULL;
-
- nf_ct_expect_related(exp);
- nf_ct_expect_put(exp);
-
- nf_ct_refresh(ct, skb, timeout * HZ);
-out:
- return NF_ACCEPT;
-}
-
static struct nf_conntrack_expect_policy exp_policy = {
.max_expected = 1,
};
+static int netbios_ns_help(struct sk_buff *skb, unsigned int protoff,
+ struct nf_conn *ct, enum ip_conntrack_info ctinfo)
+{
+ return nf_conntrack_broadcast_help(skb, protoff, ct, ctinfo, timeout);
+}
+
static struct nf_conntrack_helper helper __read_mostly = {
.name = "netbios-ns",
- .tuple.src.l3num = AF_INET,
+ .tuple.src.l3num = NFPROTO_IPV4,
.tuple.src.u.udp.port = cpu_to_be16(NMBD_PORT),
.tuple.dst.protonum = IPPROTO_UDP,
.me = THIS_MODULE,
- .help = help,
+ .help = netbios_ns_help,
.expect_policy = &exp_policy,
};
new file mode 100644
@@ -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);