[NETFILTER]: Add ctnetlink subsystem

Add ctnetlink subsystem for userspace-access to ip_conntrack table.
This allows reading and updating of existing entries, as well as
creating new ones (and new expect's) via nfnetlink.

Please note the 'strange' byte order: nfattr (tag+length) are in host
byte order, while the payload is always guaranteed to be in network
byte order.  This allows a simple userspace process to encapsulate netlink
messages into arch-independent udp packets by just processing/swapping the
headers and not knowing anything about the actual payload.

Signed-off-by: Harald Welte <laforge@netfilter.org>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

5 files changed, 85 insertions, 17 deletions

diff --git a/include/linux/netfilter_ipv4/ip_conntrack.h b/include/linux/netfilter_ipv4/ip_conntrack.h
index ae1270c97b5..ff2c1c6001f 100644
--- a/include/linux/netfilter_ipv4/ip_conntrack.h
+++ b/include/linux/netfilter_ipv4/ip_conntrack.h
@@ -209,6 +209,9 @@ struct ip_conntrack
 	/* Current number of expected connections */
 	unsigned int expecting;
 
+	/* Unique ID that identifies this conntrack*/
+	unsigned int id;
+
 	/* Helper, if any. */
 	struct ip_conntrack_helper *helper;
 
@@ -257,6 +260,9 @@ struct ip_conntrack_expect
 	/* Usage count. */
 	atomic_t use;
 
+	/* Unique ID */
+	unsigned int id;
+
 #ifdef CONFIG_IP_NF_NAT_NEEDED
 	/* This is the original per-proto part, used to map the
 	 * expected connection the way the recipient expects. */
@@ -296,7 +302,12 @@ ip_conntrack_get(const struct sk_buff *skb, enum ip_conntrack_info *ctinfo)
 }
 
 /* decrement reference count on a conntrack */
-extern void ip_conntrack_put(struct ip_conntrack *ct);
+static inline void
+ip_conntrack_put(struct ip_conntrack *ct)
+{
+	IP_NF_ASSERT(ct);
+	nf_conntrack_put(&ct->ct_general);
+}
 
 /* call to create an explicit dependency on ip_conntrack. */
 extern void need_ip_conntrack(void);
@@ -331,6 +342,39 @@ extern void
 ip_ct_iterate_cleanup(int (*iter)(struct ip_conntrack *i, void *data),
 		      void *data);
 
+extern struct ip_conntrack_helper *
+__ip_conntrack_helper_find_byname(const char *);
+extern struct ip_conntrack_helper *
+ip_conntrack_helper_find_get(const struct ip_conntrack_tuple *tuple);
+extern void ip_conntrack_helper_put(struct ip_conntrack_helper *helper);
+
+extern struct ip_conntrack_protocol *
+__ip_conntrack_proto_find(u_int8_t protocol);
+extern struct ip_conntrack_protocol *
+ip_conntrack_proto_find_get(u_int8_t protocol);
+extern void ip_conntrack_proto_put(struct ip_conntrack_protocol *proto);
+
+extern void ip_ct_remove_expectations(struct ip_conntrack *ct);
+
+extern struct ip_conntrack *ip_conntrack_alloc(struct ip_conntrack_tuple *,
+					       struct ip_conntrack_tuple *);
+
+extern void ip_conntrack_free(struct ip_conntrack *ct);
+
+extern void ip_conntrack_hash_insert(struct ip_conntrack *ct);
+
+extern struct ip_conntrack_expect *
+__ip_conntrack_expect_find(const struct ip_conntrack_tuple *tuple);
+
+extern struct ip_conntrack_expect *
+ip_conntrack_expect_find_get(const struct ip_conntrack_tuple *tuple);
+
+extern struct ip_conntrack_tuple_hash *
+__ip_conntrack_find(const struct ip_conntrack_tuple *tuple,
+                    const struct ip_conntrack *ignored_conntrack);
+
+extern void ip_conntrack_flush(void);
+
 /* It's confirmed if it is, or has been in the hash table. */
 static inline int is_confirmed(struct ip_conntrack *ct)
 {
diff --git a/include/linux/netfilter_ipv4/ip_conntrack_core.h b/include/linux/netfilter_ipv4/ip_conntrack_core.h
index 46eeea1e273..fbf6c3e4164 100644
--- a/include/linux/netfilter_ipv4/ip_conntrack_core.h
+++ b/include/linux/netfilter_ipv4/ip_conntrack_core.h
@@ -2,6 +2,9 @@
 #define _IP_CONNTRACK_CORE_H
 #include <linux/netfilter.h>
 
+#define MAX_IP_CT_PROTO 256
+extern struct ip_conntrack_protocol *ip_ct_protos[MAX_IP_CT_PROTO];
+
 /* This header is used to share core functionality between the
    standalone connection tracking module, and the compatibility layer's use
    of connection tracking. */
@@ -53,6 +56,8 @@ struct ip_conntrack_ecache;
 extern void __ip_ct_deliver_cached_events(struct ip_conntrack_ecache *ec);
 #endif
 
+extern void __ip_ct_expect_unlink_destroy(struct ip_conntrack_expect *exp);
+
 extern struct list_head *ip_conntrack_hash;
 extern struct list_head ip_conntrack_expect_list;
 extern rwlock_t ip_conntrack_lock;
diff --git a/include/linux/netfilter_ipv4/ip_conntrack_helper.h b/include/linux/netfilter_ipv4/ip_conntrack_helper.h
index 3692daa93de..8d69279ccfe 100644
--- a/include/linux/netfilter_ipv4/ip_conntrack_helper.h
+++ b/include/linux/netfilter_ipv4/ip_conntrack_helper.h
@@ -24,6 +24,8 @@ struct ip_conntrack_helper
 	int (*help)(struct sk_buff **pskb,
 		    struct ip_conntrack *ct,
 		    enum ip_conntrack_info conntrackinfo);
+
+	int (*to_nfattr)(struct sk_buff *skb, const struct ip_conntrack *ct);
 };
 
 extern int ip_conntrack_helper_register(struct ip_conntrack_helper *);
diff --git a/include/linux/netfilter_ipv4/ip_conntrack_protocol.h b/include/linux/netfilter_ipv4/ip_conntrack_protocol.h
index e20b57c5e1b..b6b99be8632 100644
--- a/include/linux/netfilter_ipv4/ip_conntrack_protocol.h
+++ b/include/linux/netfilter_ipv4/ip_conntrack_protocol.h
@@ -2,6 +2,7 @@
 #ifndef _IP_CONNTRACK_PROTOCOL_H
 #define _IP_CONNTRACK_PROTOCOL_H
 #include <linux/netfilter_ipv4/ip_conntrack.h>
+#include <linux/netfilter/nfnetlink_conntrack.h>
 
 struct seq_file;
 
@@ -47,22 +48,22 @@ struct ip_conntrack_protocol
 	int (*error)(struct sk_buff *skb, enum ip_conntrack_info *ctinfo,
 		     unsigned int hooknum);
 
+	/* convert protoinfo to nfnetink attributes */
+	int (*to_nfattr)(struct sk_buff *skb, struct nfattr *nfa,
+			 const struct ip_conntrack *ct);
+
+	int (*tuple_to_nfattr)(struct sk_buff *skb,
+			       const struct ip_conntrack_tuple *t);
+	int (*nfattr_to_tuple)(struct nfattr *tb[],
+			       struct ip_conntrack_tuple *t);
+
 	/* Module (if any) which this is connected to. */
 	struct module *me;
 };
 
-#define MAX_IP_CT_PROTO 256
-extern struct ip_conntrack_protocol *ip_ct_protos[MAX_IP_CT_PROTO];
-
 /* Protocol registration. */
 extern int ip_conntrack_protocol_register(struct ip_conntrack_protocol *proto);
 extern void ip_conntrack_protocol_unregister(struct ip_conntrack_protocol *proto);
-
-static inline struct ip_conntrack_protocol *ip_ct_find_proto(u_int8_t protocol)
-{
-	return ip_ct_protos[protocol];
-}
-
 /* Existing built-in protocols */
 extern struct ip_conntrack_protocol ip_conntrack_protocol_tcp;
 extern struct ip_conntrack_protocol ip_conntrack_protocol_udp;
@@ -73,6 +74,11 @@ extern int ip_conntrack_protocol_tcp_init(void);
 /* Log invalid packets */
 extern unsigned int ip_ct_log_invalid;
 
+extern int ip_ct_port_tuple_to_nfattr(struct sk_buff *,
+				      const struct ip_conntrack_tuple *);
+extern int ip_ct_port_nfattr_to_tuple(struct nfattr *tb[],
+				      struct ip_conntrack_tuple *);
+
 #ifdef CONFIG_SYSCTL
 #ifdef DEBUG_INVALID_PACKETS
 #define LOG_INVALID(proto) \
diff --git a/include/linux/netfilter_ipv4/ip_nat_protocol.h b/include/linux/netfilter_ipv4/ip_nat_protocol.h
index 129708c2238..ef63aa991a0 100644
--- a/include/linux/netfilter_ipv4/ip_nat_protocol.h
+++ b/include/linux/netfilter_ipv4/ip_nat_protocol.h
@@ -4,6 +4,9 @@
 #include <linux/init.h>
 #include <linux/list.h>
 
+#include <linux/netfilter_ipv4/ip_nat.h>
+#include <linux/netfilter/nfnetlink_conntrack.h>
+
 struct iphdr;
 struct ip_nat_range;
 
@@ -15,6 +18,8 @@ struct ip_nat_protocol
 	/* Protocol number. */
 	unsigned int protonum;
 
+	struct module *me;
+
 	/* Translate a packet to the target according to manip type.
 	   Return true if succeeded. */
 	int (*manip_pkt)(struct sk_buff **pskb,
@@ -43,19 +48,20 @@ struct ip_nat_protocol
 
 	unsigned int (*print_range)(char *buffer,
 				    const struct ip_nat_range *range);
-};
 
-#define MAX_IP_NAT_PROTO 256
-extern struct ip_nat_protocol *ip_nat_protos[MAX_IP_NAT_PROTO];
+	int (*range_to_nfattr)(struct sk_buff *skb,
+			       const struct ip_nat_range *range);
+
+	int (*nfattr_to_range)(struct nfattr *tb[],
+			       struct ip_nat_range *range);
+};
 
 /* Protocol registration. */
 extern int ip_nat_protocol_register(struct ip_nat_protocol *proto);
 extern void ip_nat_protocol_unregister(struct ip_nat_protocol *proto);
 
-static inline struct ip_nat_protocol *ip_nat_find_proto(u_int8_t protocol)
-{
-	return ip_nat_protos[protocol];
-}
+extern struct ip_nat_protocol *ip_nat_proto_find_get(u_int8_t protocol);
+extern void ip_nat_proto_put(struct ip_nat_protocol *proto);
 
 /* Built-in protocols. */
 extern struct ip_nat_protocol ip_nat_protocol_tcp;
@@ -67,4 +73,9 @@ extern int init_protocols(void) __init;
 extern void cleanup_protocols(void);
 extern struct ip_nat_protocol *find_nat_proto(u_int16_t protonum);
 
+extern int ip_nat_port_range_to_nfattr(struct sk_buff *skb,
+				       const struct ip_nat_range *range);
+extern int ip_nat_port_nfattr_to_range(struct nfattr *tb[],
+				       struct ip_nat_range *range);
+
 #endif /*_IP_NAT_PROTO_H*/