[NETFILTER]: Add iptables CONNMARK match+target

This is the first patch, adding something similar like nfmark, but on a
per-conntrack (as opposed to per-skb) level.  Very useful especially for
asymmatric routing in combination with MASQUERADE, as often found on
home DSL setups with dymamic IP address that also have e.g. a tunnel
device with static IP.
Signed-off-by: Henrik Nordstrom <hno@marasystems.com>
Signed-off-by: Harald Welte <laforge@netfilter.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/netfilter_ipv4/ip_conntrack.h

@@ -212,6 +212,10 @@ struct ip_conntrack
 	} nat;
 #endif /* CONFIG_IP_NF_NAT_NEEDED */
 
+#if defined(CONFIG_IP_NF_CONNTRACK_MARK)
+	unsigned long mark;
+#endif
+
 	/* Traversed often, so hopefully in different cacheline to top */
 	/* These are my tuples; original and reply */
 	struct ip_conntrack_tuple_hash tuplehash[IP_CT_DIR_MAX];

include/linux/netfilter_ipv4/ipt_CONNMARK.h

+#ifndef _IPT_CONNMARK_H_target
+#define _IPT_CONNMARK_H_target
+
+/* Copyright (C) 2002,2004 MARA Systems AB <http://www.marasystems.com>
+ * by Henrik Nordstrom <hno@marasystems.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.
+ */
+
+enum {
+	IPT_CONNMARK_SET = 0,
+	IPT_CONNMARK_SAVE,
+	IPT_CONNMARK_RESTORE
+};
+
+struct ipt_connmark_target_info {
+	unsigned long mark;
+	unsigned long mask;
+	u_int8_t mode;
+};
+
+#endif /*_IPT_CONNMARK_H_target*/

include/linux/netfilter_ipv4/ipt_connmark.h

+#ifndef _IPT_CONNMARK_H
+#define _IPT_CONNMARK_H
+
+/* Copyright (C) 2002,2004 MARA Systems AB <http://www.marasystems.com>
+ * by Henrik Nordstrom <hno@marasystems.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.
+ */
+
+struct ipt_connmark_info {
+	unsigned long mark, mask;
+	u_int8_t invert;
+};
+
+#endif /*_IPT_CONNMARK_H*/

net/ipv4/netfilter/Kconfig

@@ -32,6 +32,14 @@ config IP_NF_CT_ACCT
 
 	  If unsure, say `N'.
 
+config IP_NF_CONNTRACK_MARK
+	bool  'Connection mark tracking support'
+	help
+	  This option enables support for connection marks, used by the
+	  `CONNMARK' target and `connmark' match. Similar to the mark value
+	  of packets, but this mark value is kept in the conntrack session
+	  instead of the individual packets.
+	
 config IP_NF_CT_PROTO_SCTP
 	tristate  'SCTP protocol connection tracking support (EXPERIMENTAL)'
 	depends on IP_NF_CONNTRACK && EXPERIMENTAL
@@ -342,6 +350,17 @@ config IP_NF_MATCH_COMMENT
 	  If you want to compile it as a module, say M here and read
 	  Documentation/modules.txt.  If unsure, say `N'.
 
+config IP_NF_MATCH_CONNMARK
+	tristate  'Connection mark match support'
+	depends on IP_NF_CONNTRACK_MARK && IP_NF_IPTABLES
+	help
+	  This option adds a `connmark' match, which allows you to match the
+	  connection mark value previously set for the session by `CONNMARK'. 
+	
+	  If you want to compile it as a module, say M here and read
+	  Documentation/modules.txt.  The module will be called
+	  ipt_connmark.o.  If unsure, say `N'.
+
 # `filter', generic and specific targets
 config IP_NF_FILTER
 	tristate "Packet filtering"
@@ -597,6 +616,18 @@ config IP_NF_TARGET_CLASSIFY
 
 	  To compile it as a module, choose M here.  If unsure, say N.
 
+config IP_NF_TARGET_CONNMARK
+	tristate  'CONNMARK target support'
+	depends on IP_NF_CONNTRACK_MARK && IP_NF_MANGLE
+	help
+	  This option adds a `CONNMARK' target, which allows one to manipulate
+	  the connection mark value.  Similar to the MARK target, but
+	  affects the connection mark value rather than the packet mark value.
+	
+	  If you want to compile it as a module, say M here and read
+	  Documentation/modules.txt.  The module will be called
+	  ipt_CONNMARK.o.  If unsure, say `N'.
+
 # raw + specific targets
 config IP_NF_RAW
 	tristate  'raw table support (required for NOTRACK/TRACE)'

net/ipv4/netfilter/Makefile

@@ -61,6 +61,7 @@ obj-$(CONFIG_IP_NF_MATCH_AH_ESP) += ipt_ah.o ipt_esp.o
 obj-$(CONFIG_IP_NF_MATCH_LENGTH) += ipt_length.o
 obj-$(CONFIG_IP_NF_MATCH_TTL) += ipt_ttl.o
 obj-$(CONFIG_IP_NF_MATCH_STATE) += ipt_state.o
+obj-$(CONFIG_IP_NF_MATCH_CONNMARK) += ipt_connmark.o
 obj-$(CONFIG_IP_NF_MATCH_CONNTRACK) += ipt_conntrack.o
 obj-$(CONFIG_IP_NF_MATCH_TCPMSS) += ipt_tcpmss.o
 obj-$(CONFIG_IP_NF_MATCH_REALM) += ipt_realm.o
@@ -81,6 +82,7 @@ obj-$(CONFIG_IP_NF_TARGET_SAME) += ipt_SAME.o
 obj-$(CONFIG_IP_NF_TARGET_CLASSIFY) += ipt_CLASSIFY.o
 obj-$(CONFIG_IP_NF_NAT_SNMP_BASIC) += ip_nat_snmp_basic.o
 obj-$(CONFIG_IP_NF_TARGET_LOG) += ipt_LOG.o
+obj-$(CONFIG_IP_NF_TARGET_CONNMARK) += ipt_CONNMARK.o
 obj-$(CONFIG_IP_NF_TARGET_ULOG) += ipt_ULOG.o
 obj-$(CONFIG_IP_NF_TARGET_TCPMSS) += ipt_TCPMSS.o
 obj-$(CONFIG_IP_NF_TARGET_NOTRACK) += ipt_NOTRACK.o

net/ipv4/netfilter/ip_conntrack_core.c

@@ -594,6 +594,9 @@ init_conntrack(const struct ip_conntrack_tuple *tuple,
 		__set_bit(IPS_EXPECTED_BIT, &conntrack->status);
 		conntrack->master = expected;
 		expected->sibling = conntrack;
+#if CONFIG_IP_NF_CONNTRACK_MARK
+		conntrack->mark = expected->expectant->mark;
+#endif
 		LIST_DELETE(&ip_conntrack_expect_list, expected);
 		expected->expectant->expecting--;
 		nf_conntrack_get(&master_ct(conntrack)->ct_general);

net/ipv4/netfilter/ip_conntrack_standalone.c

@@ -146,6 +146,11 @@ static int ct_seq_real_show(const struct ip_conntrack_tuple_hash *hash,
 		if (seq_printf(s, "[ASSURED] "))
 			return 1;
 
+#if defined(CONFIG_IP_NF_CONNTRACK_MARK)
+	if (seq_printf(s, "mark=%ld ", conntrack->mark))
+		return 1;
+#endif
+
 	if (seq_printf(s, "use=%u\n", atomic_read(&conntrack->ct_general.use)))
 		return 1;
 

net/ipv4/netfilter/ipt_CONNMARK.c

+/* This kernel module is used to modify the connection mark values, or
+ * to optionally restore the skb nfmark from the connection mark
+ *
+ * Copyright (C) 2002,2004 MARA Systems AB <http://www.marasystems.com>
+ * by Henrik Nordstrom <hno@marasystems.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.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+#include <linux/module.h>
+#include <linux/skbuff.h>
+#include <linux/ip.h>
+#include <net/checksum.h>
+
+MODULE_AUTHOR("Henrik Nordstrom <hno@marasytems.com>");
+MODULE_DESCRIPTION("IP tables CONNMARK matching module");
+MODULE_LICENSE("GPL");
+
+#include <linux/netfilter_ipv4/ip_tables.h>
+#include <linux/netfilter_ipv4/ipt_CONNMARK.h>
+#include <linux/netfilter_ipv4/ip_conntrack.h>
+
+static unsigned int
+target(struct sk_buff **pskb,
+       const struct net_device *in,
+       const struct net_device *out,
+       unsigned int hooknum,
+       const void *targinfo,
+       void *userinfo)
+{
+	const struct ipt_connmark_target_info *markinfo = targinfo;
+	unsigned long diff;
+	unsigned long nfmark;
+	unsigned long newmark;
+
+	enum ip_conntrack_info ctinfo;
+	struct ip_conntrack *ct = ip_conntrack_get((*pskb), &ctinfo);
+	if (ct) {
+	    switch(markinfo->mode) {
+	    case IPT_CONNMARK_SET:
+		newmark = (ct->mark & ~markinfo->mask) | markinfo->mark;
+		if (newmark != ct->mark)
+		    ct->mark = newmark;
+		break;
+	    case IPT_CONNMARK_SAVE:
+		newmark = (ct->mark & ~markinfo->mask) | ((*pskb)->nfmark & markinfo->mask);
+		if (ct->mark != newmark)
+		    ct->mark = newmark;
+		break;
+	    case IPT_CONNMARK_RESTORE:
+		nfmark = (*pskb)->nfmark;
+		diff = (ct->mark ^ nfmark & markinfo->mask);
+		if (diff != 0) {
+		    (*pskb)->nfmark = nfmark ^ diff;
+		    (*pskb)->nfcache |= NFC_ALTERED;
+		}
+		break;
+	    }
+	}
+
+	return IPT_CONTINUE;
+}
+
+static int
+checkentry(const char *tablename,
+	   const struct ipt_entry *e,
+	   void *targinfo,
+	   unsigned int targinfosize,
+	   unsigned int hook_mask)
+{
+	struct ipt_connmark_target_info *matchinfo = targinfo;
+	if (targinfosize != IPT_ALIGN(sizeof(struct ipt_connmark_target_info))) {
+		printk(KERN_WARNING "CONNMARK: targinfosize %u != %Zu\n",
+		       targinfosize,
+		       IPT_ALIGN(sizeof(struct ipt_connmark_target_info)));
+		return 0;
+	}
+
+	if (matchinfo->mode == IPT_CONNMARK_RESTORE) {
+	    if (strcmp(tablename, "mangle") != 0) {
+		    printk(KERN_WARNING "CONNMARK: restore can only be called from \"mangle\" table, not \"%s\"\n", tablename);
+		    return 0;
+	    }
+	}
+
+	return 1;
+}
+
+static struct ipt_target ipt_connmark_reg = {
+	.name = "CONNMARK",
+	.target = &target,
+	.checkentry = &checkentry,
+	.me = THIS_MODULE
+};
+
+static int __init init(void)
+{
+	return ipt_register_target(&ipt_connmark_reg);
+}
+
+static void __exit fini(void)
+{
+	ipt_unregister_target(&ipt_connmark_reg);
+}
+
+module_init(init);
+module_exit(fini);

net/ipv4/netfilter/ipt_connmark.c

+/* This kernel module matches connection mark values set by the
+ * CONNMARK target
+ *
+ * Copyright (C) 2002,2004 MARA Systems AB <http://www.marasystems.com>
+ * by Henrik Nordstrom <hno@marasystems.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.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+
+#include <linux/module.h>
+#include <linux/skbuff.h>
+
+MODULE_AUTHOR("Henrik Nordstrom <hno@marasytems.com>");
+MODULE_DESCRIPTION("IP tables connmark match module");
+MODULE_LICENSE("GPL");
+
+#include <linux/netfilter_ipv4/ip_tables.h>
+#include <linux/netfilter_ipv4/ipt_connmark.h>
+#include <linux/netfilter_ipv4/ip_conntrack.h>
+
+static int
+match(const struct sk_buff *skb,
+      const struct net_device *in,
+      const struct net_device *out,
+      const void *matchinfo,
+      int offset,
+      int *hotdrop)
+{
+	const struct ipt_connmark_info *info = matchinfo;
+	enum ip_conntrack_info ctinfo;
+	struct ip_conntrack *ct = ip_conntrack_get((struct sk_buff *)skb, &ctinfo);
+	if (!ct)
+		return 0;
+
+	return ((ct->mark & info->mask) == info->mark) ^ info->invert;
+}
+
+static int
+checkentry(const char *tablename,
+	   const struct ipt_ip *ip,
+	   void *matchinfo,
+	   unsigned int matchsize,
+	   unsigned int hook_mask)
+{
+	if (matchsize != IPT_ALIGN(sizeof(struct ipt_connmark_info)))
+		return 0;
+
+	return 1;
+}
+
+static struct ipt_match connmark_match = {
+	.name = "connmark",
+	.match = &match,
+	.checkentry = &checkentry,
+	.me = THIS_MODULE
+};
+
+static int __init init(void)
+{
+	return ipt_register_match(&connmark_match);
+}
+
+static void __exit fini(void)
+{
+	ipt_unregister_match(&connmark_match);
+}
+
+module_init(init);
+module_exit(fini);