netfilter: log: split family specific code to nf_log_{ip,ip6,common}.c files

The plain text logging is currently embedded into the xt_LOG target.
In order to be able to use the plain text logging from nft_log, as a
first step, this patch moves the family specific code to the following
files and Kconfig symbols:

1) net/ipv4/netfilter/nf_log_ip.c: CONFIG_NF_LOG_IPV4
2) net/ipv6/netfilter/nf_log_ip6.c: CONFIG_NF_LOG_IPV6
3) net/netfilter/nf_log_common.c: CONFIG_NF_LOG_COMMON

These new modules will be required by xt_LOG and nft_log. This patch
is based on original patch from Arturo Borrero Gonzalez.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

include/net/netfilter/nf_log.h

@@ -78,4 +78,32 @@ struct nf_log_buf *nf_log_buf_open(void);
 __printf(2, 3) int nf_log_buf_add(struct nf_log_buf *m, const char *f, ...);
 void nf_log_buf_close(struct nf_log_buf *m);
 
+void nf_log_ip_packet(struct net *net, u_int8_t pf,
+		      unsigned int hooknum, const struct sk_buff *skb,
+		      const struct net_device *in,
+		      const struct net_device *out,
+		      const struct nf_loginfo *loginfo,
+		      const char *prefix);
+
+void nf_log_ip6_packet(struct net *net, u_int8_t pf,
+		       unsigned int hooknum, const struct sk_buff *skb,
+		       const struct net_device *in,
+		       const struct net_device *out,
+		       const struct nf_loginfo *loginfo,
+		       const char *prefix);
+
+/* common logging functions */
+int nf_log_dump_udp_header(struct nf_log_buf *m, const struct sk_buff *skb,
+			   u8 proto, int fragment, unsigned int offset);
+int nf_log_dump_tcp_header(struct nf_log_buf *m, const struct sk_buff *skb,
+			   u8 proto, int fragment, unsigned int offset,
+			   unsigned int logflags);
+void nf_log_dump_sk_uid_gid(struct nf_log_buf *m, struct sock *sk);
+void nf_log_dump_packet_common(struct nf_log_buf *m, u_int8_t pf,
+			       unsigned int hooknum, const struct sk_buff *skb,
+			       const struct net_device *in,
+			       const struct net_device *out,
+			       const struct nf_loginfo *loginfo,
+			       const char *prefix);
+
 #endif /* _NF_LOG_H */

net/ipv4/netfilter/Kconfig

@@ -159,6 +159,11 @@ config IP_NF_TARGET_SYNPROXY
 
 	  To compile it as a module, choose M here. If unsure, say N.
 
+config NF_LOG_IPV4
+	tristate "IPv4 packet logging"
+	default m if NETFILTER_ADVANCED=n
+	select NF_LOG_COMMON
+
 # NAT + specific targets: nf_conntrack
 config NF_NAT_IPV4
 	tristate "IPv4 NAT"

net/ipv4/netfilter/Makefile

@@ -19,6 +19,9 @@ obj-$(CONFIG_NF_NAT_IPV4) += nf_nat_ipv4.o
 # defrag
 obj-$(CONFIG_NF_DEFRAG_IPV4) += nf_defrag_ipv4.o
 
+# logging
+obj-$(CONFIG_NF_LOG_IPV4) += nf_log_ipv4.o
+
 # NAT helpers (nf_conntrack)
 obj-$(CONFIG_NF_NAT_H323) += nf_nat_h323.o
 obj-$(CONFIG_NF_NAT_PPTP) += nf_nat_pptp.o

net/ipv6/netfilter/Kconfig

@@ -227,6 +227,11 @@ config IP6_NF_SECURITY
 
          If unsure, say N.
 
+config NF_LOG_IPV6
+	tristate "IPv6 packet logging"
+	depends on NETFILTER_ADVANCED
+	select NF_LOG_COMMON
+
 config NF_NAT_IPV6
 	tristate "IPv6 NAT"
 	depends on NF_CONNTRACK_IPV6

net/ipv6/netfilter/Makefile

@@ -23,6 +23,9 @@ obj-$(CONFIG_NF_NAT_IPV6) += nf_nat_ipv6.o
 nf_defrag_ipv6-y := nf_defrag_ipv6_hooks.o nf_conntrack_reasm.o
 obj-$(CONFIG_NF_DEFRAG_IPV6) += nf_defrag_ipv6.o
 
+# logging
+obj-$(CONFIG_NF_LOG_IPV6) += nf_log_ipv6.o
+
 # nf_tables
 obj-$(CONFIG_NF_TABLES_IPV6) += nf_tables_ipv6.o
 obj-$(CONFIG_NFT_CHAIN_ROUTE_IPV6) += nft_chain_route_ipv6.o

net/netfilter/Kconfig

@@ -359,6 +359,9 @@ config NETFILTER_NETLINK_QUEUE_CT
 	  If this option is enabled, NFQUEUE can include Connection Tracking
 	  information together with the packet is the enqueued via NFNETLINK.
 
+config NF_LOG_COMMON
+	tristate
+
 config NF_NAT
 	tristate
 
@@ -744,6 +747,9 @@ config NETFILTER_XT_TARGET_LED
 
 config NETFILTER_XT_TARGET_LOG
 	tristate "LOG target support"
+	select NF_LOG
+	select NF_LOG_IPV4
+	select NF_LOG_IPV6
 	default m if NETFILTER_ADVANCED=n
 	help
 	  This option adds a `LOG' target, which allows you to create rules in

net/netfilter/Makefile

@@ -47,6 +47,9 @@ obj-$(CONFIG_NF_CONNTRACK_TFTP) += nf_conntrack_tftp.o
 nf_nat-y	:= nf_nat_core.o nf_nat_proto_unknown.o nf_nat_proto_common.o \
 		   nf_nat_proto_udp.o nf_nat_proto_tcp.o nf_nat_helper.o
 
+# generic transport layer logging
+obj-$(CONFIG_NF_LOG_COMMON) += nf_log_common.o
+
 obj-$(CONFIG_NF_NAT) += nf_nat.o
 
 # NAT protocols (nf_nat)

net/netfilter/nf_log_common.c

+/* (C) 1999-2001 Paul `Rusty' Russell
+ * (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/module.h>
+#include <linux/spinlock.h>
+#include <linux/skbuff.h>
+#include <linux/if_arp.h>
+#include <linux/ip.h>
+#include <net/icmp.h>
+#include <net/udp.h>
+#include <net/tcp.h>
+#include <net/route.h>
+
+#include <linux/netfilter.h>
+#include <linux/netfilter/xt_LOG.h>
+#include <net/netfilter/nf_log.h>
+
+int nf_log_dump_udp_header(struct nf_log_buf *m, const struct sk_buff *skb,
+			   u8 proto, int fragment, unsigned int offset)
+{
+	struct udphdr _udph;
+	const struct udphdr *uh;
+
+	if (proto == IPPROTO_UDP)
+		/* Max length: 10 "PROTO=UDP "     */
+		nf_log_buf_add(m, "PROTO=UDP ");
+	else	/* Max length: 14 "PROTO=UDPLITE " */
+		nf_log_buf_add(m, "PROTO=UDPLITE ");
+
+	if (fragment)
+		goto out;
+
+	/* Max length: 25 "INCOMPLETE [65535 bytes] " */
+	uh = skb_header_pointer(skb, offset, sizeof(_udph), &_udph);
+	if (uh == NULL) {
+		nf_log_buf_add(m, "INCOMPLETE [%u bytes] ", skb->len - offset);
+
+		return 1;
+	}
+
+	/* Max length: 20 "SPT=65535 DPT=65535 " */
+	nf_log_buf_add(m, "SPT=%u DPT=%u LEN=%u ",
+		       ntohs(uh->source), ntohs(uh->dest), ntohs(uh->len));
+
+out:
+	return 0;
+}
+EXPORT_SYMBOL_GPL(nf_log_dump_udp_header);
+
+int nf_log_dump_tcp_header(struct nf_log_buf *m, const struct sk_buff *skb,
+			   u8 proto, int fragment, unsigned int offset,
+			   unsigned int logflags)
+{
+	struct tcphdr _tcph;
+	const struct tcphdr *th;
+
+	/* Max length: 10 "PROTO=TCP " */
+	nf_log_buf_add(m, "PROTO=TCP ");
+
+	if (fragment)
+		return 0;
+
+	/* Max length: 25 "INCOMPLETE [65535 bytes] " */
+	th = skb_header_pointer(skb, offset, sizeof(_tcph), &_tcph);
+	if (th == NULL) {
+		nf_log_buf_add(m, "INCOMPLETE [%u bytes] ", skb->len - offset);
+		return 1;
+	}
+
+	/* Max length: 20 "SPT=65535 DPT=65535 " */
+	nf_log_buf_add(m, "SPT=%u DPT=%u ",
+		       ntohs(th->source), ntohs(th->dest));
+	/* Max length: 30 "SEQ=4294967295 ACK=4294967295 " */
+	if (logflags & XT_LOG_TCPSEQ) {
+		nf_log_buf_add(m, "SEQ=%u ACK=%u ",
+			       ntohl(th->seq), ntohl(th->ack_seq));
+	}
+
+	/* Max length: 13 "WINDOW=65535 " */
+	nf_log_buf_add(m, "WINDOW=%u ", ntohs(th->window));
+	/* Max length: 9 "RES=0x3C " */
+	nf_log_buf_add(m, "RES=0x%02x ", (u_int8_t)(ntohl(tcp_flag_word(th) &
+					    TCP_RESERVED_BITS) >> 22));
+	/* Max length: 32 "CWR ECE URG ACK PSH RST SYN FIN " */
+	if (th->cwr)
+		nf_log_buf_add(m, "CWR ");
+	if (th->ece)
+		nf_log_buf_add(m, "ECE ");
+	if (th->urg)
+		nf_log_buf_add(m, "URG ");
+	if (th->ack)
+		nf_log_buf_add(m, "ACK ");
+	if (th->psh)
+		nf_log_buf_add(m, "PSH ");
+	if (th->rst)
+		nf_log_buf_add(m, "RST ");
+	if (th->syn)
+		nf_log_buf_add(m, "SYN ");
+	if (th->fin)
+		nf_log_buf_add(m, "FIN ");
+	/* Max length: 11 "URGP=65535 " */
+	nf_log_buf_add(m, "URGP=%u ", ntohs(th->urg_ptr));
+
+	if ((logflags & XT_LOG_TCPOPT) && th->doff*4 > sizeof(struct tcphdr)) {
+		u_int8_t _opt[60 - sizeof(struct tcphdr)];
+		const u_int8_t *op;
+		unsigned int i;
+		unsigned int optsize = th->doff*4 - sizeof(struct tcphdr);
+
+		op = skb_header_pointer(skb, offset + sizeof(struct tcphdr),
+					optsize, _opt);
+		if (op == NULL) {
+			nf_log_buf_add(m, "OPT (TRUNCATED)");
+			return 1;
+		}
+
+		/* Max length: 127 "OPT (" 15*4*2chars ") " */
+		nf_log_buf_add(m, "OPT (");
+		for (i = 0; i < optsize; i++)
+			nf_log_buf_add(m, "%02X", op[i]);
+
+		nf_log_buf_add(m, ") ");
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(nf_log_dump_tcp_header);
+
+void nf_log_dump_sk_uid_gid(struct nf_log_buf *m, struct sock *sk)
+{
+	if (!sk || sk->sk_state == TCP_TIME_WAIT)
+		return;
+
+	read_lock_bh(&sk->sk_callback_lock);
+	if (sk->sk_socket && sk->sk_socket->file) {
+		const struct cred *cred = sk->sk_socket->file->f_cred;
+		nf_log_buf_add(m, "UID=%u GID=%u ",
+			from_kuid_munged(&init_user_ns, cred->fsuid),
+			from_kgid_munged(&init_user_ns, cred->fsgid));
+	}
+	read_unlock_bh(&sk->sk_callback_lock);
+}
+EXPORT_SYMBOL_GPL(nf_log_dump_sk_uid_gid);
+
+void
+nf_log_dump_packet_common(struct nf_log_buf *m, u_int8_t pf,
+			  unsigned int hooknum, const struct sk_buff *skb,
+			  const struct net_device *in,
+			  const struct net_device *out,
+			  const struct nf_loginfo *loginfo, const char *prefix)
+{
+	nf_log_buf_add(m, KERN_SOH "%c%sIN=%s OUT=%s ",
+	       '0' + loginfo->u.log.level, prefix,
+	       in ? in->name : "",
+	       out ? out->name : "");
+#ifdef CONFIG_BRIDGE_NETFILTER
+	if (skb->nf_bridge) {
+		const struct net_device *physindev;
+		const struct net_device *physoutdev;
+
+		physindev = skb->nf_bridge->physindev;
+		if (physindev && in != physindev)
+			nf_log_buf_add(m, "PHYSIN=%s ", physindev->name);
+		physoutdev = skb->nf_bridge->physoutdev;
+		if (physoutdev && out != physoutdev)
+			nf_log_buf_add(m, "PHYSOUT=%s ", physoutdev->name);
+	}
+#endif
+}
+EXPORT_SYMBOL_GPL(nf_log_dump_packet_common);
+
+static int __init nf_log_common_init(void)
+{
+	return 0;
+}
+
+static void __exit nf_log_common_exit(void) {}
+
+module_init(nf_log_common_init);
+module_exit(nf_log_common_exit);
+
+MODULE_LICENSE("GPL");