[NETFILTER]: Extend netfilter logging API

This patch is in preparation to nfnetlink_log:
- loggers now have to register struct nf_logger instead of nf_logfn
- nf_log_unregister() replaced by nf_log_unregister_pf() and
  nf_log_unregister_logger()
- add comment to ip[6]t_LOG.h to assure nobody redefines flags
- add /proc/net/netfilter/nf_log to tell user which logger is currently
  registered for which address family
- if user has configured logging, but no logging backend (logger) is
  available, always spit a message to syslog, not just the first time.
- split ip[6]t_LOG.c into two parts:
  Backend: Always try to register as logger for the respective address family
  Frontend: Always log via nf_log_packet() API
- modify all users of nf_log_packet() to accomodate additional argument

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

include/linux/netfilter.h

@@ -114,15 +114,51 @@ void nf_unregister_sockopt(struct nf_sockopt_ops *reg);
 
 extern struct list_head nf_hooks[NPROTO][NF_MAX_HOOKS];
 
-typedef void nf_logfn(unsigned int hooknum,
+/* those NF_LOG_* defines and struct nf_loginfo are legacy definitios that will
+ * disappear once iptables is replaced with pkttables.  Please DO NOT use them
+ * for any new code! */
+#define NF_LOG_TCPSEQ		0x01	/* Log TCP sequence numbers */
+#define NF_LOG_TCPOPT		0x02	/* Log TCP options */
+#define NF_LOG_IPOPT		0x04	/* Log IP options */
+#define NF_LOG_UID		0x08	/* Log UID owning local socket */
+#define NF_LOG_MASK		0x0f
+
+#define NF_LOG_TYPE_LOG		0x01
+#define NF_LOG_TYPE_ULOG	0x02
+
+struct nf_loginfo {
+	u_int8_t type;
+	union {
+		struct {
+			u_int32_t copy_len;
+			u_int16_t group;
+			u_int16_t qthreshold;
+		} ulog;
+		struct {
+			u_int8_t level;
+			u_int8_t logflags;
+		} log;
+	} u;
+};
+
+typedef void nf_logfn(unsigned int pf,
+		      unsigned int hooknum,
 		      const struct sk_buff *skb,
 		      const struct net_device *in,
 		      const struct net_device *out,
+		      const struct nf_loginfo *li,
 		      const char *prefix);
 
+struct nf_logger {
+	struct module	*me;
+	nf_logfn 	*logfn;
+	char		*name;
+};
+
 /* Function to register/unregister log function. */
-int nf_log_register(int pf, nf_logfn *logfn);
-void nf_log_unregister(int pf, nf_logfn *logfn);
+int nf_log_register(int pf, struct nf_logger *logger);
+void nf_log_unregister_pf(int pf);
+void nf_log_unregister_logger(struct nf_logger *logger);
 
 /* Calls the registered backend logging function */
 void nf_log_packet(int pf,
@@ -130,6 +166,7 @@ void nf_log_packet(int pf,
 		   const struct sk_buff *skb,
 		   const struct net_device *in,
 		   const struct net_device *out,
+		   struct nf_loginfo *li,
 		   const char *fmt, ...);
                    
 /* Activate hook; either okfn or kfree_skb called, unless a hook
@@ -221,6 +258,11 @@ struct nf_queue_rerouter {
 extern int nf_register_queue_rerouter(int pf, struct nf_queue_rerouter *rer);
 extern int nf_unregister_queue_rerouter(int pf);
 
+#ifdef CONFIG_PROC_FS
+#include <linux/proc_fs.h>
+extern struct proc_dir_entry *proc_net_netfilter;
+#endif
+
 #else /* !CONFIG_NETFILTER */
 #define NF_HOOK(pf, hook, skb, indev, outdev, okfn) (okfn)(skb)
 static inline void nf_ct_attach(struct sk_buff *new, struct sk_buff *skb) {}

include/linux/netfilter_ipv4/ipt_LOG.h

@@ -1,6 +1,7 @@
 #ifndef _IPT_LOG_H
 #define _IPT_LOG_H
 
+/* make sure not to change this without changing netfilter.h:NF_LOG_* (!) */
 #define IPT_LOG_TCPSEQ		0x01	/* Log TCP sequence numbers */
 #define IPT_LOG_TCPOPT		0x02	/* Log TCP options */
 #define IPT_LOG_IPOPT		0x04	/* Log IP options */

include/linux/netfilter_ipv6/ip6t_LOG.h

@@ -1,6 +1,7 @@
 #ifndef _IP6T_LOG_H
 #define _IP6T_LOG_H
 
+/* make sure not to change this without changing netfilter.h:NF_LOG_* (!) */
 #define IP6T_LOG_TCPSEQ		0x01	/* Log TCP sequence numbers */
 #define IP6T_LOG_TCPOPT		0x02	/* Log TCP options */
 #define IP6T_LOG_IPOPT		0x04	/* Log IP options */