[v2 PATCH 0/2] NETFILTER new target module, HMARK

[v2 PATCH 0/2] NETFILTER new target module, HMARK

[Hans Schillstrom]

The target allows you to create rules in the "raw" and "mangle" tables
which alter the netfilter mark (nfmark) field within a given range.
First a 32 bit hash value is generated then modulus by <limit> and
finally an offset is added before it's written to nfmark.
Prior to routing, the nfmark can influence the routing method (see
"Use netfilter MARK value as routing key") and can also be used by
other subsystems to change their behaviour.

The mark match can also be used to match nfmark produced by this module.
See the kernel module for more info.

REVISION

Version 2
	NAT Added for IPv4
	IPv6 ICMP handling enhanced.
	Usage example added

Version 1
	Initial RFC


We (Ericsson) use hmark in-front of ipvs as a pre-loadbalancer and
handles up to 70 ipvs running in parallel in clusters.
However hmark is not restricted to run infront of IPVS it can also be used as
"poor mans" load balancer.
With this version is also NAT supported as an option, with very high flows
you might not want to use conntrack.

The idea is to generate a direction independent fw mark range to use as input to
the routing (i.e. ip rule add fwmark ...).
Pretty straight forward and simple.


Example:
                                      App Server (Real Server)

                                           +---------+
                                        -->| Service |
     Gateway A                             +---------+
                          /
            +----------+ /     +----+      +---------+
--- if -A---| selector |---->  |ipvs|  --->| Service |
            +----------+ \     +----+      +---------+
                          \
                               +----+      +---------+
                               |ipvs|   -->| Service |
                               +----+      +---------+
      Gateway C
            +----------+ /     +----+
--- if-B ---| selector | --->  |ipvs|
            +----------+ \     +----+      +---------+
                                           | Service |
                                           +---------+
                          /
            +----------+ /     +----+     ..
--- if-B ---| selector | --->  |ipvs|      +---------+
            +----------+ \     +----+      | Service |
                          \                +---------+
#
# Example with four ipvs loadbalancers
#
iptables -t mangle -I PREROUTING -d $IPADDR -j HMARK --hmark-mod 4 --hmark-offs 100

ip rule add fwmark 100 table 100
ip rule add fwmark 101 table 101
ip rule add fwmark 102 table 102
ip rule add fwmark 103 table 103

ip ro ad table 100 default via x.y.z.1 dev bond1
ip ro ad table 101 default via x.y.z.2 dev bond1
ip ro ad table 102 default via x.y.z.3 dev bond1
ip ro ad table 103 default via x.y.z.4 dev bond1


If conntrack doesn't handle the return path,
do the oposite with HMARK and send it back right to ipvs.

Another exmaple of usage could be if you have cluster originated connections
and want to spread the connections over a number of interfaces
(NAT will complpicate things for you in this case)



                     \  Blade 1
                      \ +----------+      +---------+
                    <-- | selector | <--- | Service |
                      / +----------+      +---------+
                     /
   +------+
-- | Gw-A |          \  Blade 2
   +------+           \ +----------+      +---------+
   +------+         <-- | selector | <--- | Service |
-- | Gw-B |           / +----------+      +---------+
   +------+          /
   +------+
-- | Gw-C |          \
   +------+           \ +----------+      +---------+
                    <-- | selector | <--- | Service |
                      / +----------+      +---------+
                     /

                     \  Blande -n
                      \ +----------+      +---------+
                    <-- | selector | <--- | Service |
                      / +----------+      +---------+
                     /

Regards
Hans Schillstrom <hans.schillstrom@ericsson.com>

[v2 PATCH 1/2] NETFILTER module xt_hmark new target for HASH based fw

[Hans Schillstrom]

The target allows you to create rules in the "raw" and "mangle" tables
which alter the netfilter mark (nfmark) field within a given range.
First a 32 bit hash value is generated then modulus by <limit> and
finally an offset is added before it's written to nfmark.
Prior to routing, the nfmark can influence the routing method (see
"Use netfilter MARK value as routing key") and can also be used by
other subsystems to change their behavior.

man page
   HMARK
       This  module  does  the same as MARK, i.e. set an fwmark,
       but the mark is based on a hash value.  The hash is based on
       saddr, daddr, sport, dport and proto. The same mark will be produced
       independet of direction if no masks is set or the same masks is used for
       src and dest. The hash mark could be adjusted by modulus and finaly an
       offset could be added, i.e the final mark will be within a range.
       ICMP errors will have hash calc based on the original message.
       Note: None of the parameters effect the packet it self
       only the calculated hash value.

       Parameters: For all masks default is all "1:s", to disable a field
                   use mask 0. For IPv6 it's just the last 32 bits that
                   is included in the hash.

       --hmark-smask value
              The value to AND the source address with (saddr & value).

       --hmark-dmask value
              The value to AND the dest. address with (daddr & value).

       --hmark-sp-mask value
              A 16 bit value to AND the src port with (sport & value).

       --hmark-dp-mask value
              A 16 bit value to AND the dest port with (dport & value).

       --hmark-sp-set value
              A 16 bit value to OR the src port with (sport | value).

       --hmark-dp-set value
              A 16 bit value to OR the dest port with (dport | value).

       --hmark-spi-mask value
              Value to AND the spi field with (spi & value) valid for proto esp or ah.

       --hmark-spi-set value
              Value to OR the spi field with (spi | value) valid for proto esp or ah.

       --hmark-proto-mask value
              A 16 bit value to AND the L4 proto field with (proto & value).

       --hmark-rnd value
              A 32 bit intitial value for hash calc, default is 0xc175a3b8.

       --hmark-dnat
              Replace src addr/port with original dst addr/port before calc, hash

       --hmark-snat
              Replace dst addr/port with original src addr/port before calc, hash

       Final processing of the mark in order of execution.

       --hmark-mod value (must be > 0)
              The easiest way to describe this is:  hash = hash mod <value>

       --hmark-offs alue (must be > 0)
              The easiest way to describe this is:  hash = hash + <value>

       Examples:

       Default rule handles all TCP, UDP, SCTP, ESP & AH

Rev 2
      IPv6 header scan changed to follow RFC 2640
      IPv4 icmp echo fragmented does now use proto as ipv6
      IPv6 pskb_may_pull() check is done in every time in header loop.
      IPv4 nat support added.
      default added in IPv6 loop and null check of hp

Signed-off-by: Hans Schillstrom <hans.schillstrom@ericsson.com>
---
 include/linux/netfilter/xt_hmark.h |   48 ++++++
 net/netfilter/Kconfig              |   17 ++
 net/netfilter/Makefile             |    1 +
 net/netfilter/xt_hmark.c           |  320 ++++++++++++++++++++++++++++++++++++
 4 files changed, 386 insertions(+), 0 deletions(-)
 create mode 100644 include/linux/netfilter/xt_hmark.h
 create mode 100644 net/netfilter/xt_hmark.c

diff --git a/include/linux/netfilter/xt_hmark.h b/include/linux/netfilter/xt_hmark.h
new file mode 100644
index 0000000..6c1436a
--- /dev/null
+++ b/include/linux/netfilter/xt_hmark.h
@@ -0,0 +1,48 @@
+#ifndef XT_HMARK_H_
+#define XT_HMARK_H_
+
+#include <linux/types.h>
+
+/*
+ * Flags must not start at 0, since it's used as none.
+ */
+enum {
+	XT_HMARK_SADR_AND = 1,	/* SNAT & DNAT are used by the kernel module */
+	XT_HMARK_DADR_AND,
+	XT_HMARK_SPI_AND,
+	XT_HMARK_SPI_OR,
+	XT_HMARK_SPORT_AND,
+	XT_HMARK_DPORT_AND,
+	XT_HMARK_SPORT_OR,
+	XT_HMARK_DPORT_OR,
+	XT_HMARK_PROTO_AND,
+	XT_HMARK_RND,
+	XT_HMARK_MODULUS,
+	XT_HMARK_OFFSET,
+	XT_HMARK_USE_SNAT,
+	XT_HMARK_USE_DNAT,
+};
+
+union ports {
+	struct {
+		__u16	src;
+		__u16	dst;
+	} p16;
+	__u32	v32;
+};
+
+struct xt_hmark_info {
+	__u32		smask;		/* Source address mask */
+	__u32		dmask;		/* Dest address mask */
+	union ports	pmask;
+	union ports	pset;
+	__u32		spimask;
+	__u32		spiset;
+	__u16		flags;		/* Print out only */
+	__u16		prmask;		/* L4 Proto mask */
+	__u32		hashrnd;
+	__u32		hmod;		/* Modulus */
+	__u32		hoffs;		/* Offset */
+};
+
+#endif /* XT_HMARK_H_ */
diff --git a/net/netfilter/Kconfig b/net/netfilter/Kconfig
index 32bff6d..3abd3a4 100644
--- a/net/netfilter/Kconfig
+++ b/net/netfilter/Kconfig
@@ -483,6 +483,23 @@ config NETFILTER_XT_TARGET_IDLETIMER
 
 	  To compile it as a module, choose M here.  If unsure, say N.
 
+config NETFILTER_XT_TARGET_HMARK
+	tristate '"HMARK" target support'
+	depends on NETFILTER_ADVANCED
+	---help---
+	This option adds the "HMARK" target.
+
+	The target allows you to create rules in the "raw" and "mangle" tables
+	which alter the netfilter mark (nfmark) field within a given range.
+	First a 32 bit hash value is generated then modulus by <limit> and
+	finally an offset is added before it's written to nfmark.
+
+	Prior to routing, the nfmark can influence the routing method (see
+	"Use netfilter MARK value as routing key") and can also be used by
+	other subsystems to change their behavior.
+
+	The mark match can also be used to match nfmark produced by this module.
+
 config NETFILTER_XT_TARGET_LED
 	tristate '"LED" target support'
 	depends on LEDS_CLASS && LEDS_TRIGGERS
diff --git a/net/netfilter/Makefile b/net/netfilter/Makefile
index 1a02853..359eeb6 100644
--- a/net/netfilter/Makefile
+++ b/net/netfilter/Makefile
@@ -56,6 +56,7 @@ obj-$(CONFIG_NETFILTER_XT_TARGET_CONNSECMARK) += xt_CONNSECMARK.o
 obj-$(CONFIG_NETFILTER_XT_TARGET_CT) += xt_CT.o
 obj-$(CONFIG_NETFILTER_XT_TARGET_DSCP) += xt_DSCP.o
 obj-$(CONFIG_NETFILTER_XT_TARGET_HL) += xt_HL.o
+obj-$(CONFIG_NETFILTER_XT_TARGET_HMARK) += xt_hmark.o
 obj-$(CONFIG_NETFILTER_XT_TARGET_LED) += xt_LED.o
 obj-$(CONFIG_NETFILTER_XT_TARGET_NFLOG) += xt_NFLOG.o
 obj-$(CONFIG_NETFILTER_XT_TARGET_NFQUEUE) += xt_NFQUEUE.o
diff --git a/net/netfilter/xt_hmark.c b/net/netfilter/xt_hmark.c
new file mode 100644
index 0000000..2f0aa93
--- /dev/null
+++ b/net/netfilter/xt_hmark.c
@@ -0,0 +1,320 @@
+/*
+ *	xt_hmark - Netfilter module to set mark as hash value
+ *
+ *	(C) 2010 Hans Schillstrom <hans.schillstrom@ericsson.com>
+ *
+ *	Description:
+ *	This module calculates a hash value that can be modified by modulus
+ *	and an offset. The hash value is based on a direction independent
+ *	five tuple: src & dst addr src & dst ports and protocol.
+ *	However src & dst port can be masked and are not used for fragmented
+ *	packets, ESP and AH don't have ports so SPI will be used instead.
+ *	For ICMP error messages the hash mark values will be calculated on
+ *	the source packet i.e. the packet caused the error (If sufficient
+ *	amount of data exists).
+ *
+ *	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/skbuff.h>
+#include <net/ip.h>
+#include <linux/icmp.h>
+
+#include <linux/netfilter/xt_hmark.h>
+#include <linux/netfilter/x_tables.h>
+#include <net/netfilter/nf_nat.h>
+
+#if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
+#	define WITH_IPV6 1
+#include <net/ipv6.h>
+#include <linux/netfilter_ipv6/ip6_tables.h>
+#endif
+
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Hans Schillstrom <hans.schillstrom@ericsson.com>");
+MODULE_DESCRIPTION("Xtables: packet range mark operations by hash value");
+MODULE_ALIAS("ipt_HMARK");
+MODULE_ALIAS("ip6t_HMARK");
+
+/*
+ * ICMP, get inner header so calc can be made on the source message
+ *       not the icmp header, i.e. same hash mark must be produced
+ *       on an icmp error message.
+ */
+static int get_inner_hdr(struct sk_buff *skb, int iphsz, int nhoff)
+{
+	const struct icmphdr *icmph;
+	struct icmphdr _ih;
+	struct iphdr *iph = NULL;
+
+	/* Not enough header? */
+	icmph = skb_header_pointer(skb, nhoff + iphsz, sizeof(_ih), &_ih);
+	if (icmph == NULL)
+		goto out;
+
+	if (icmph->type > NR_ICMP_TYPES)
+		goto out;
+
+
+	/* Error message? */
+	if (icmph->type != ICMP_DEST_UNREACH &&
+	    icmph->type != ICMP_SOURCE_QUENCH &&
+	    icmph->type != ICMP_TIME_EXCEEDED &&
+	    icmph->type != ICMP_PARAMETERPROB &&
+	    icmph->type != ICMP_REDIRECT)
+		goto out;
+	/* Checkin full IP header plus 8 bytes of protocol to
+	 * avoid additional coding at protocol handlers.
+	 */
+	if (!pskb_may_pull(skb, nhoff + iphsz + sizeof(_ih) + 8))
+		goto out;
+
+	iph = (struct iphdr *)(skb->data + nhoff + iphsz + sizeof(_ih));
+	return nhoff + iphsz + sizeof(_ih);
+out:
+	return nhoff;
+}
+/*
+ * ICMPv6
+ * Input nhoff Offset into network header
+ *       offset where ICMPv6 header starts
+ * Returns true if it's a icmp error and updates nhoff
+ */
+#ifdef WITH_IPV6
+static int get_inner6_hdr(struct sk_buff *skb, int *offset, int hdrlen)
+{
+	struct icmp6hdr *icmp6h;
+	struct icmp6hdr _ih6;
+
+	icmp6h = skb_header_pointer(skb, *offset + hdrlen, sizeof(_ih6), &_ih6);
+	if (icmp6h == NULL)
+		goto out;
+
+	if (icmp6h->icmp6_type && icmp6h->icmp6_type < 128) {
+		*offset += hdrlen + sizeof(_ih6);
+		return 1;
+	}
+out:
+	return 0;
+}
+#endif
+
+/*
+ * Calc hash value, special casre is taken on icmp and fragmented messages
+ * i.e. fragmented messages don't use ports.
+ */
+static __u32 get_hash(struct sk_buff *skb, struct xt_hmark_info *info)
+{
+	int nhoff, hash = 0, poff, proto, frag = 0;
+	struct iphdr *ip;
+	u8 ip_proto;
+	u32 addr1, addr2, ihl;
+	u16 snatport = 0, dnatport = 0;
+	union {
+		u32 v32;
+		u16 v16[2];
+	} ports;
+
+	nhoff = skb_network_offset(skb);
+	proto = skb->protocol;
+
+	if (!proto && skb->sk) {
+		if (skb->sk->sk_family == AF_INET)
+			proto = __constant_htons(ETH_P_IP);
+		else if (skb->sk->sk_family == AF_INET6)
+			proto = __constant_htons(ETH_P_IPV6);
+	}
+
+	switch (proto) {
+	case __constant_htons(ETH_P_IP):
+	{
+		enum ip_conntrack_info ctinfo;
+		struct nf_conn *ct = ct = nf_ct_get(skb, &ctinfo);
+		struct nf_conntrack_tuple *otuple, *rtuple;
+
+		if (!pskb_may_pull(skb, sizeof(*ip) + nhoff))
+			goto done;
+
+		ip = (struct iphdr *) (skb->data + nhoff);
+		if (ip->protocol == IPPROTO_ICMP) {
+			/* Switch hash calc to inner header ? */
+			nhoff = get_inner_hdr(skb, ip->ihl * 4, nhoff);
+			ip = (struct iphdr *) (skb->data + nhoff);
+		}
+
+		if (ip->frag_off & htons(IP_MF | IP_OFFSET))
+			frag = 1;
+
+		ip_proto = ip->protocol;
+		ihl = ip->ihl;
+		addr1 = (__force u32) ip->saddr & info->smask;
+		addr2 = (__force u32) ip->daddr & info->dmask;
+
+		if (!ct || !nf_ct_is_confirmed(ct))
+			break;
+		otuple = &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple;
+		/* On the "return flow", to get the original address
+		 * i,e, replace the source address.
+		 */
+		if (ct->status & IPS_DST_NAT &&
+		    info->flags & XT_HMARK_USE_DNAT) {
+			rtuple = &ct->tuplehash[IP_CT_DIR_REPLY].tuple;
+			addr1 = (__force u32) otuple->dst.u3.in.s_addr;
+			dnatport = otuple->dst.u.udp.port;
+		}
+		/* On the "return flow", to get the original address
+		 * i,e, replace the destination address.
+		 */
+		if (ct->status & IPS_SRC_NAT &&
+		    info->flags & XT_HMARK_USE_SNAT) {
+			rtuple = &ct->tuplehash[IP_CT_DIR_REPLY].tuple;
+			addr2 = (__force u32) otuple->src.u3.in.s_addr;
+			snatport = otuple->src.u.udp.port;
+		}
+		break;
+	}
+#ifdef WITH_IPV6
+	case __constant_htons(ETH_P_IPV6):
+	{
+		struct ipv6hdr *ip6;	/* ip hdr */
+		int hdrlen = 0;	/* In ip header */
+		u8 nexthdr;
+		int ip6hdrlvl = 0;	/* Header level */
+		struct ipv6_opt_hdr _hdr, *hp;
+
+hdr_new:
+		if (!pskb_may_pull(skb, sizeof(*ip6) + nhoff))
+			goto done;
+
+		/* ip header */
+		ip6 = (struct ipv6hdr *) (skb->data + nhoff);
+		nexthdr = ip6->nexthdr;
+		/* nhoff += sizeof(struct ipv6hdr);  Where hdr starts */
+		hdrlen = sizeof(struct ipv6hdr);
+		hp = skb_header_pointer(skb, nhoff + hdrlen, sizeof(_hdr),
+					&_hdr);
+		while (nexthdr) {
+			switch (nexthdr) {
+			case IPPROTO_ICMPV6:
+				/* ICMP Error then move ptr to inner header */
+				if (get_inner6_hdr(skb, &nhoff, hdrlen)) {
+					ip6hdrlvl++;
+					goto hdr_new;
+				}
+				nhoff += hdrlen;
+				goto hdr_rdy;
+
+			case NEXTHDR_FRAGMENT:
+				if (!ip6hdrlvl)
+					frag = 1;
+				break;
+			/* End of hdr traversing */
+			case NEXTHDR_IPV6:	/* Do not process tunnels */
+			case NEXTHDR_TCP:
+			case NEXTHDR_UDP:
+			case NEXTHDR_ESP:
+			case NEXTHDR_AUTH:
+			case NEXTHDR_NONE:
+				nhoff += hdrlen;
+				goto hdr_rdy;
+			default:
+				goto done;
+			}
+			if (!hp)
+				goto done;
+			nhoff += hdrlen;	/* eat current header */
+			nexthdr =  hp->nexthdr;	/* Next header */
+			hdrlen = ipv6_optlen(hp);
+			hp = skb_header_pointer(skb, nhoff + hdrlen,
+						sizeof(_hdr), &_hdr);
+
+			if (!pskb_may_pull(skb, nhoff))
+				goto done;
+		}
+hdr_rdy:
+		ip_proto = nexthdr;
+
+		addr1 = (__force u32) ip6->saddr.s6_addr32[3];
+		addr2 = (__force u32) ip6->daddr.s6_addr32[3];
+		ihl = 0; /* (40 >> 2); */
+		break;
+	}
+#endif
+	default:
+		goto done;
+	}
+
+	ports.v32 = 0;
+	poff = proto_ports_offset(ip_proto);
+	nhoff += ihl * 4 + poff;
+	if (!frag && poff >= 0 && pskb_may_pull(skb, nhoff + 4)) {
+		ports.v32 = * (__force u32 *) (skb->data + nhoff);
+		if (ip_proto == IPPROTO_ESP || ip_proto == IPPROTO_AH) {
+			ports.v32 = (ports.v32 & info->spimask) | info->spiset;
+		} else { /* Handle endian */
+			if (snatport)	/* Replace snated dst port (ret flow) */
+				ports.v16[1] = snatport;
+			if (dnatport)
+				ports.v16[0] = dnatport;
+			ports.v32 = (ports.v32 & info->pmask.v32) |
+				    info->pset.v32;
+			if (ports.v16[1] < ports.v16[0])
+				swap(ports.v16[0], ports.v16[1]);
+		}
+	}
+	ip_proto &= info->prmask;
+	/* get a consistent hash (same value on both flow directions) */
+	if (addr2 < addr1)
+		swap(addr1, addr2);
+
+	hash = jhash_3words(addr1, addr2, ports.v32, info->hashrnd) ^ ip_proto;
+	if (!hash)
+		hash = 1;
+
+	return hash;
+
+done:
+	return 0;
+}
+
+static unsigned int
+hmark_tg(struct sk_buff *skb, const struct xt_action_param *par)
+{
+	struct xt_hmark_info *info = (struct xt_hmark_info *)par->targinfo;
+	__u32 hash = get_hash(skb, info);
+
+	if (info->hmod && hash)
+		skb->mark = (hash % info->hmod) + info->hoffs;
+	return XT_CONTINUE;
+}
+
+static struct xt_target hmark_tg_reg __read_mostly = {
+	.name           = "HMARK",
+	.revision       = 0,
+	.family         = NFPROTO_UNSPEC,
+	.target         = hmark_tg,
+	.targetsize     = sizeof(struct xt_hmark_info),
+	.me             = THIS_MODULE,
+};
+
+static int __init hmark_mt_init(void)
+{
+	int ret;
+
+	ret = xt_register_target(&hmark_tg_reg);
+	if (ret < 0)
+		return ret;
+	return 0;
+}
+
+static void __exit hmark_mt_exit(void)
+{
+	xt_unregister_target(&hmark_tg_reg);
+}
+
+module_init(hmark_mt_init);
+module_exit(hmark_mt_exit);
-- 
1.7.4.4

[v2 PATCH 2/2] NETFILTER userspace part for target HMARK

[Hans Schillstrom]

The target allows you to create rules in the "raw" and "mangle" tables
which alter the netfilter mark (nfmark) field within a given range.
First a 32 bit hash value is generated then modulus by <limit> and
finally an offset is added before it's written to nfmark.
Prior to routing, the nfmark can influence the routing method (see
"Use netfilter MARK value as routing key") and can also be used by
other subsystems to change their behaviour.

The mark match can also be used to match nfmark produced by this module.

Ver 2
  IPv4 NAT added
  iptables ver 1.4.12.1 adaptions.

Signed-off-by: Hans Schillstrom <hans.schillstrom@ericsson.com>
---
 extensions/libxt_HMARK.c           |  381 ++++++++++++++++++++++++++++++++++++
 extensions/libxt_HMARK.man         |   66 ++++++
 include/linux/netfilter/xt_hmark.h |   48 +++++
 3 files changed, 495 insertions(+), 0 deletions(-)
 create mode 100644 extensions/libxt_HMARK.c
 create mode 100644 extensions/libxt_HMARK.man
 create mode 100644 include/linux/netfilter/xt_hmark.h

diff --git a/extensions/libxt_HMARK.c b/extensions/libxt_HMARK.c
new file mode 100644
index 0000000..0def034
--- /dev/null
+++ b/extensions/libxt_HMARK.c
@@ -0,0 +1,381 @@
+/*
+ * Shared library add-on to iptables to add HMARK target support.
+ *
+ * The kernel module calculates a hash value that can be modified by modulus
+ * and an offset. The hash value is based on a direction independent
+ * five tuple: src & dst addr src & dst ports and protocol.
+ * However src & dst port can be masked and are not used for fragmented
+ * packets, ESP and AH don't have ports so SPI will be used instead.
+ * For ICMP error messages the hash mark values will be calculated on
+ * the source packet i.e. the packet caused the error (If sufficient
+ * amount of data exists).
+ * 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 <stdbool.h>
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+#include <getopt.h>
+
+#include <xtables.h>
+#include <linux/netfilter/x_tables.h>
+#include <linux/netfilter/xt_hmark.h>
+
+
+#define DEF_HRAND 0xc175a3b8	/* Default "random" value to jhash */
+
+static void HMARK_help(void)
+{
+	printf(
+"HMARK target options, i.e. modify hash calculation by:\n"
+"  --hmark-smask value                Mask source address with value\n"
+"  --hmark-dmask value                Mask Dest. address with value\n"
+"  --hmark-sp-mask value              Mask src port with value\n"
+"  --hmark-dp-mask value              Mask dst port with value\n"
+"  --hmark-spi-mask value             For esp and ah AND spi with value\n"
+"  --hmark-sp-set value               OR src port with value\n"
+"  --hmark-dp-set value               OR dst port with value\n"
+"  --hmark-spi-set value              For esp and ah OR spi with value\n"
+"  --hmark-proto-mask value           Mask Protocol with value\n"
+"  --hmark-rnd                        Random value to hash cacl.\n"
+"  Limit/modify the calculated hash mark by:\n"
+"  --hmark-mod value                  nfmark modulus value\n"
+"  --hmark-offs value                 Last action add value to nfmark\n"
+" For NAT in IPv4 the original address can be used in the return path.\n"
+" Make sure to qualify the statement in a proper way when using nat flags\n"
+"  --hmark-dnat                       Replace src addr/port with original dst addr/port\n"
+"  --hmark-snat                       Replace dst addr/port with original src addr/port\n"
+" In many cases hmark can be omitted i.e. --smask can be used\n");
+}
+
+static const struct option HMARK_opts[] = {
+	{ "hmark-smask", 1, NULL, XT_HMARK_SADR_AND },
+	{ "hmark-dmask", 1, NULL, XT_HMARK_DADR_AND },
+	{ "hmark-sp-mask", 1, NULL, XT_HMARK_SPORT_AND },
+	{ "hmark-dp-mask", 1, NULL, XT_HMARK_DPORT_AND },
+	{ "hmark-spi-mask", 1, NULL, XT_HMARK_SPI_AND },
+	{ "hmark-sp-set", 1, NULL, XT_HMARK_SPORT_OR },
+	{ "hmark-dp-set", 1, NULL, XT_HMARK_DPORT_OR },
+	{ "hmark-spi-set", 1, NULL, XT_HMARK_SPI_OR },
+	{ "hmark-proto-mask", 1, NULL, XT_HMARK_PROTO_AND },
+	{ "hmark-rnd", 1, NULL, XT_HMARK_RND },
+	{ "hmark-mod", 1, NULL, XT_HMARK_MODULUS },
+	{ "hmark-offs", 1, NULL, XT_HMARK_OFFSET },
+	{ "hmark-dnat", 1, NULL, XT_HMARK_USE_DNAT },
+	{ "hmark-snat", 1, NULL, XT_HMARK_USE_SNAT },
+	{ "smask", 1, NULL, XT_HMARK_SADR_AND },
+	{ "dmask", 1, NULL, XT_HMARK_DADR_AND },
+	{ "sp-mask", 1, NULL, XT_HMARK_SPORT_AND },
+	{ "dp-mask", 1, NULL, XT_HMARK_DPORT_AND },
+	{ "spi-mask", 1, NULL, XT_HMARK_SPI_AND },
+	{ "sp-set", 1, NULL, XT_HMARK_SPORT_OR },
+	{ "dp-set", 1, NULL, XT_HMARK_DPORT_OR },
+	{ "spi-set", 1, NULL, XT_HMARK_SPI_OR },
+	{ "proto-mask", 1, NULL, XT_HMARK_PROTO_AND },
+	{ "rnd", 1, NULL, XT_HMARK_RND },
+	{ "mod", 1, NULL, XT_HMARK_MODULUS },
+	{ "offs", 1, NULL, XT_HMARK_OFFSET },
+	{ "dnat", 1, NULL, XT_HMARK_USE_DNAT },
+	{ "snat", 1, NULL, XT_HMARK_USE_SNAT },
+	{ .name = NULL }
+};
+
+static int
+HMARK_parse(int c, char **argv, int invert, unsigned int *flags,
+	    const void *entry, struct xt_entry_target **target)
+{
+	struct xt_hmark_info *hmarkinfo
+		= (struct xt_hmark_info *)(*target)->data;
+	unsigned int value = 0xffffffff;
+	unsigned int maxint = UINT32_MAX;
+
+	if ((c < XT_HMARK_SADR_AND) || (c > XT_HMARK_OFFSET)) {
+		xtables_error(PARAMETER_PROBLEM, "Bad HMARK option \"%s\"",
+			      optarg);
+		return 0;
+	}
+
+	if (c >= XT_HMARK_SPORT_AND && c <= XT_HMARK_DPORT_OR)
+		maxint = UINT16_MAX;
+	else if (c == XT_HMARK_PROTO_AND)
+		maxint = UINT8_MAX;
+
+	if (!xtables_strtoui(optarg, NULL, &value, 0, maxint))
+		xtables_error(PARAMETER_PROBLEM, "Bad HMARK value \"%s\"",
+			      optarg);
+
+	if (*flags == 0) {
+		memset(hmarkinfo, 0xff, sizeof(struct xt_hmark_info));
+		hmarkinfo->pset.v32 = 0;
+		hmarkinfo->flags = 0;
+		hmarkinfo->spiset = 0;
+		hmarkinfo->hoffs = 0;
+		hmarkinfo->hashrnd = DEF_HRAND;
+	}
+	switch (c) {
+	case XT_HMARK_SADR_AND:
+		if (*flags & (1 << c)) {
+			xtables_error(PARAMETER_PROBLEM,
+				      "Can only specify "
+				      "`--hmark-smask' once");
+		}
+		hmarkinfo->smask = htonl(value);
+		if (value == maxint)
+			c = 0;
+		break;
+
+	case XT_HMARK_DADR_AND:
+		if (*flags & (1 << c)) {
+			xtables_error(PARAMETER_PROBLEM,
+				      "Can only specify "
+				      "`--hmark-dmask' once");
+		}
+		hmarkinfo->dmask = htonl(value);
+		if (value == maxint)
+			c = 0;
+		break;
+
+	case XT_HMARK_MODULUS:
+		if (*flags & (1 << c)) {
+			xtables_error(PARAMETER_PROBLEM,
+				      "Can only specify "
+				      "`--hmark-mod' once");
+		}
+		if (value == 0) {
+			xtables_error(PARAMETER_PROBLEM,
+				      "xxx modulus 0 ? "
+				      "thats a div by 0");
+			value = 0xffffffff;
+		}
+		hmarkinfo->hmod = value;
+		if (value == maxint)
+			c = 0;
+		break;
+
+	case XT_HMARK_OFFSET:
+		if (*flags & (1 << c)) {
+			xtables_error(PARAMETER_PROBLEM,
+				      "Can only specify "
+				      "`--hmark-offs' once");
+		}
+		hmarkinfo->hoffs = value;
+		if (value == 0)
+			c = 0;
+		break;
+
+	case XT_HMARK_SPORT_AND:
+		if (*flags & (1 << c)) {
+			xtables_error(PARAMETER_PROBLEM,
+				      "Can only specify "
+				      "`--hmark-sp-mask' once");
+		}
+		hmarkinfo->pmask.p16.src = htons(value);
+		if (value == maxint)
+			c = 0;
+		break;
+
+	case XT_HMARK_DPORT_AND:
+		if (*flags & (1 << c)) {
+			xtables_error(PARAMETER_PROBLEM,
+				      "Can only specify "
+				      "`--hmark-dp-mask' once");
+		}
+		hmarkinfo->pmask.p16.dst = htons(value);
+		if (value == maxint)
+			c = 0;
+		break;
+
+	case XT_HMARK_SPI_AND:
+		if (*flags & (1 << c)) {
+			xtables_error(PARAMETER_PROBLEM,
+				      "Can only specify "
+				      "`--hmark-spi-mask' once");
+		}
+		hmarkinfo->spimask = htonl(value);
+		if (value == maxint)
+			c = 0;
+		break;
+
+	case XT_HMARK_SPORT_OR:
+		if (*flags & (1 << c)) {
+			xtables_error(PARAMETER_PROBLEM,
+				      "Can only specify "
+				      "`--hmark-sp-set' once");
+		}
+		hmarkinfo->pset.p16.src = htons(value);
+		if (!value)
+			c = 0;
+		break;
+
+	case XT_HMARK_DPORT_OR:
+		if (*flags & (1 << c)) {
+			xtables_error(PARAMETER_PROBLEM,
+				      "Can only specify "
+				      "`--hmark-dp-set' once");
+		}
+		hmarkinfo->pset.p16.dst = htons(value);
+		if (!value)
+			c = 0;
+		break;
+
+	case XT_HMARK_SPI_OR:
+		if (*flags & (1 << c)) {
+			xtables_error(PARAMETER_PROBLEM,
+				      "Can only specify "
+				      "`--hmark-spi-set' once");
+		}
+		hmarkinfo->spiset = htonl(value);
+		if (!value)
+			c = 0;
+		break;
+
+	case XT_HMARK_PROTO_AND:
+		if (*flags & (1 << c)) {
+			xtables_error(PARAMETER_PROBLEM,
+				      "Can only specify "
+				      "`--hmark-proto-mask' once");
+		}
+		hmarkinfo->prmask = value;
+		if (value == maxint)
+			c = 0;
+		break;
+
+	case XT_HMARK_RND:
+		if (*flags & (1 << c)) {
+			xtables_error(PARAMETER_PROBLEM,
+				      "Can only specify `--hmark-rnd' once");
+		}
+		hmarkinfo->hashrnd = value;
+		if (value == DEF_HRAND)
+			c = 0;
+		break;
+
+	case XT_HMARK_USE_DNAT:
+		if (*flags & (1 << c)) {
+			xtables_error(PARAMETER_PROBLEM,
+				      "Can only specify `--hmark-rnd' once");
+		}
+		break;
+
+	case XT_HMARK_USE_SNAT:
+		if (*flags & (1 << c)) {
+			xtables_error(PARAMETER_PROBLEM,
+				      "Can only specify `--hmark-rnd' once");
+		}
+		break;
+
+	default:
+		return 0;
+	}
+	*flags |= 1 << c;
+	hmarkinfo->flags = *flags;
+
+	return 1;
+}
+
+static void HMARK_check(unsigned int flags)
+{
+	if (!(flags & (1 << XT_HMARK_MODULUS)))
+		xtables_error(PARAMETER_PROBLEM, "HMARK: the --hmark-mod, "
+			   "is not set, that means the nfmark will be in range"
+			   " 0 - 0xffffffff");
+}
+
+static void HMARK_print(const void *ip, const struct xt_entry_target *target,
+			int numeric)
+{
+	const struct xt_hmark_info *info =
+			(const struct xt_hmark_info *)target->data;
+
+	printf(" HMARK ");
+	if (info->flags & (1 << XT_HMARK_USE_SNAT))
+		printf("snat, ");
+	if (info->flags & (1 << XT_HMARK_SADR_AND))
+		printf("smask 0x%x ", htonl(info->smask));
+
+	if (info->flags & (1 << XT_HMARK_USE_DNAT))
+		printf("dnat, ");
+	if (info->flags & (1 << XT_HMARK_DADR_AND))
+		printf("dmask 0x%x ", htonl(info->dmask));
+
+	if (info->flags & (1 << XT_HMARK_SPORT_AND))
+		printf("sp-mask 0x%x ", htons(info->pmask.p16.src));
+	if (info->flags & (1 << XT_HMARK_DPORT_AND))
+		printf("dp-mask 0x%x ", htons(info->pmask.p16.dst));
+	if (info->flags & (1 << XT_HMARK_SPI_AND))
+		printf("spi-mask 0x%x ", htonl(info->spimask));
+	if (info->flags & (1 << XT_HMARK_SPORT_OR))
+		printf("sp-set 0x%x ", htons(info->pset.p16.src));
+	if (info->flags & (1 << XT_HMARK_DPORT_OR))
+		printf("dp-set 0x%x ", htons(info->pset.p16.dst));
+	if (info->flags & (1 << XT_HMARK_SPI_OR))
+		printf("spi-set 0x%x ", htonl(info->spiset));
+	if (info->flags & (1 << XT_HMARK_PROTO_AND))
+		printf("proto-mask 0x%x ", info->prmask);
+	if (info->flags & (1 << XT_HMARK_RND))
+		printf("rnd 0x%x ", info->hashrnd);
+	if (info->flags & (1 << XT_HMARK_MODULUS))
+		printf("mark=hv %% 0x%x ", info->hmod);
+	if (info->flags & (1 << XT_HMARK_OFFSET))
+		printf("+ 0x%x ", info->hoffs);
+}
+
+static void HMARK_save(const void *ip, const struct xt_entry_target *target)
+{
+	const struct xt_hmark_info *info =
+		(const struct xt_hmark_info *)target->data;
+
+	if (info->flags & (1 << XT_HMARK_SADR_AND))
+		printf("--hmark-smask 0x%x ", htonl(info->smask));
+	if (info->flags & (1 << XT_HMARK_DADR_AND))
+		printf("--hmark-dmask 0x%x ", htonl(info->dmask));
+	if (info->flags & (1 << XT_HMARK_SPORT_AND))
+		printf("--hmark-sp-mask 0x%x ", htons(info->pmask.p16.src));
+	if (info->flags & (1 << XT_HMARK_DPORT_AND))
+		printf("--hmark-dp-mask 0x%x ", htons(info->pmask.p16.dst));
+	if (info->flags & (1 << XT_HMARK_SPI_AND))
+		printf("--hmark-spi-mask 0x%x ", htonl(info->spimask));
+	if (info->flags & (1 << XT_HMARK_SPORT_OR))
+		printf("--hmark-sp-set 0x%x ", htons(info->pset.p16.src));
+	if (info->flags & (1 << XT_HMARK_DPORT_OR))
+		printf("--hmark-dp-set 0x%x ", htons(info->pset.p16.dst));
+	if (info->flags & (1 << XT_HMARK_SPI_OR))
+		printf("--hmark-spi-set 0x%x ", htonl(info->spiset));
+	if (info->flags & (1 << XT_HMARK_PROTO_AND))
+		printf("--hmark-proto-mask 0x%x ", info->prmask);
+	if (info->flags & (1 << XT_HMARK_RND))
+		printf("--hmark-rnd 0x%x ", info->hashrnd);
+	if (info->flags & (1 << XT_HMARK_MODULUS))
+		printf("--hmark-mod 0x%x ", info->hmod);
+	if (info->flags & (1 << XT_HMARK_OFFSET))
+		printf("--hmark-offs 0x%x ", info->hoffs);
+	if (info->flags & (1 << XT_HMARK_USE_DNAT))
+		printf("--hmark-dnat ");
+	if (info->flags & (1 << XT_HMARK_USE_SNAT))
+		printf("--hmark-snat ");
+}
+
+static struct xtables_target mark_tg_reg[] = {
+	{
+		.family        = NFPROTO_UNSPEC,
+		.name          = "HMARK",
+		.version       = XTABLES_VERSION,
+		.revision      = 0,
+		.size          = XT_ALIGN(sizeof(struct xt_hmark_info)),
+		.userspacesize = XT_ALIGN(sizeof(struct xt_hmark_info)),
+		.help          = HMARK_help,
+		.parse         = HMARK_parse,
+		.final_check   = HMARK_check,
+		.print         = HMARK_print,
+		.save          = HMARK_save,
+		.extra_opts    = HMARK_opts,
+	},
+};
+
+void _init(void)
+{
+	xtables_register_targets(mark_tg_reg, ARRAY_SIZE(mark_tg_reg));
+}
+
diff --git a/extensions/libxt_HMARK.man b/extensions/libxt_HMARK.man
new file mode 100644
index 0000000..8f44676
--- /dev/null
+++ b/extensions/libxt_HMARK.man
@@ -0,0 +1,66 @@
+This module does the same as MARK, i.e. set an fwmark, but the mark is based on a hash value.
+The hash is based on saddr, daddr, sport, dport and proto. The same mark will be produced independet of direction if no masks is set or the same masks is used for src and dest.
+The hash mark could be adjusted by modulus and finally an offset could be added, i.e the final mark will be within a range. If state RELATED is used icmp will be handled also, i.e. hash will be calculated on the original message not the icmp it self.
+Note: None of the parameters effect the packet it self only the calculated hash value.
+.PP
+Parameters:
+For all masks default is all "1:s", to disable a field use mask 0
+For IPv6 it's just the last 32 bits that is included in the hash
+.TP
+\fB\-\-hmark\-smask\fP \fIvalue\fP
+The value to AND the source address with (saddr & value).
+.TP
+\fB\-\-hmark\-dmask\fP \fIvalue\fP
+The value to AND the dest. address with (daddr & value).
+.TP
+\fB\-\-hmark\-sp\-mask\fP \fIvalue\fP
+A 16 bit value to AND the src port with (sport & value).
+.TP
+\fB\-\-hmark\-dp\-mask\fP \fIvalue\fP
+A 16 bit value to AND the dest port with (dport & value).
+.TP
+\fB\-\-hmark\-sp\-set\fP \fIvalue\fP
+A 16 bit value to OR the src port with (sport | value).
+.TP
+\fB\-\-hmark\-dp\-set\fP \fIvalue\fP
+A 16 bit value to OR the dest port with (dport | value).
+.TP
+\fB\-\-hmark\-spi\-mask\fP \fIvalue\fP
+Value to AND the spi field with (spi & value) valid for proto esp or ah.
+.TP
+\fB\-\-hmark\-spi\-set\fP \fIvalue\fP
+Value to OR the spi field with (spi | value) valid for proto esp or ah.
+.TP
+\fB\-\-hmark\-proto\-mask\fP \fIvalue\fP
+An 8 bit value to AND the L4 proto field with (proto & value).
+.TP
+\fB\-\-hmark\-rnd\fP \fIvalue\fP
+A 32 bit initial value for hash calc, default is 0xc175a3b8.
+.TP
+\fB\-\-hmark\-dnat\fP
+Replace src addr/port with original dst addr/port before calc, hash
+.TP
+\fB\-\-hmark\-dnat\fP
+Replace dst addr/port with original src addr/port before calc, hash
+.PP
+Final processing of the mark in order of execution.
+.TP
+\fB\-\-hmark\-mod\fP \fvalue (must be > 0)\fP
+The easiest way to describe this is:  hash = hash mod <value>
+.TP
+\fB\-\-hmark\-offs\fP \fvalue\fP
+The easiest way to describe this is:  hash = hash + <value>
+.PP
+\fIExamples:\fP
+.PP
+Default rule handles all TCP, UDP, SCTP, ESP & AH
+.IP
+iptables \-t mangle \-A PREROUTING \-m state \-\-state NEW,ESTABLISHED,RELATED
+ \-j HMARK \-\-hmark-offs 10000 \-\-hmark-mod 10
+.PP
+Handle SCTP and hash dest port only and produce a nfmark between 100-119.
+.IP
+iptables \-t mangle \-A PREROUTING -p SCTP \-j HMARK \-\-smask 0 \-\-dmask 0
+ \-\-sp\-mask 0 \-\-offs 100 \-\-mod 20
+.PP
+
diff --git a/include/linux/netfilter/xt_hmark.h b/include/linux/netfilter/xt_hmark.h
new file mode 100644
index 0000000..7b3ee5d
--- /dev/null
+++ b/include/linux/netfilter/xt_hmark.h
@@ -0,0 +1,48 @@
+#ifndef XT_HMARK_H_
+#define XT_HMARK_H_
+
+#include <linux/types.h>
+
+/*
+ * Flags must not start at 0, since it's used as none.
+ */
+enum {
+	XT_HMARK_USE_SNAT = 1,	/* SNAT & DNAT are used by the kernel module */
+	XT_HMARK_USE_DNAT,
+	XT_HMARK_SADR_AND,
+	XT_HMARK_DADR_AND,
+	XT_HMARK_SPI_AND,
+	XT_HMARK_SPI_OR,
+	XT_HMARK_SPORT_AND,
+	XT_HMARK_DPORT_AND,
+	XT_HMARK_SPORT_OR,
+	XT_HMARK_DPORT_OR,
+	XT_HMARK_PROTO_AND,
+	XT_HMARK_RND,
+	XT_HMARK_MODULUS,
+	XT_HMARK_OFFSET,
+};
+
+union ports {
+	struct {
+		__u16	src;
+		__u16	dst;
+	} p16;
+	__u32	v32;
+};
+
+struct xt_hmark_info {
+	__u32		smask;		/* Source address mask */
+	__u32		dmask;		/* Dest address mask */
+	union ports	pmask;
+	union ports	pset;
+	__u32		spimask;
+	__u32		spiset;
+	__u16		flags;		/* Print out only */
+	__u16		prmask;		/* L4 Proto mask */
+	__u32		hashrnd;
+	__u32		hmod;		/* Modulus */
+	__u32		hoffs;		/* Offset */
+};
+
+#endif /* XT_HMARK_H_ */
-- 
1.7.4.4

Re: [v2 PATCH 1/2] NETFILTER module xt_hmark new target for HASH based fw

[Pablo Neira Ayuso]

Hi Hans,

On Mon, Oct 03, 2011 at 07:46:42PM +0200, Hans Schillstrom wrote:
> diff --git a/include/linux/netfilter/xt_hmark.h b/include/linux/netfilter/xt_hmark.h
> new file mode 100644
> index 0000000..6c1436a
> --- /dev/null
> +++ b/include/linux/netfilter/xt_hmark.h
> @@ -0,0 +1,48 @@
> +#ifndef XT_HMARK_H_
> +#define XT_HMARK_H_
> +
> +#include <linux/types.h>
> +
> +/*
> + * Flags must not start at 0, since it's used as none.
> + */
> +enum {
> +	XT_HMARK_SADR_AND = 1,	/* SNAT & DNAT are used by the kernel module */
> +	XT_HMARK_DADR_AND,
> +	XT_HMARK_SPI_AND,
> +	XT_HMARK_SPI_OR,
> +	XT_HMARK_SPORT_AND,
> +	XT_HMARK_DPORT_AND,
> +	XT_HMARK_SPORT_OR,
> +	XT_HMARK_DPORT_OR,
> +	XT_HMARK_PROTO_AND,
> +	XT_HMARK_RND,
> +	XT_HMARK_MODULUS,
> +	XT_HMARK_OFFSET,
> +	XT_HMARK_USE_SNAT,
> +	XT_HMARK_USE_DNAT,
> +};
> +
> +union ports {
> +	struct {
> +		__u16	src;
> +		__u16	dst;
> +	} p16;
> +	__u32	v32;
> +};
> +
> +struct xt_hmark_info {
> +	__u32		smask;		/* Source address mask */
> +	__u32		dmask;		/* Dest address mask */
> +	union ports	pmask;
> +	union ports	pset;
> +	__u32		spimask;
> +	__u32		spiset;
> +	__u16		flags;		/* Print out only */
> +	__u16		prmask;		/* L4 Proto mask */
> +	__u32		hashrnd;
> +	__u32		hmod;		/* Modulus */
> +	__u32		hoffs;		/* Offset */
> +};
> +
> +#endif /* XT_HMARK_H_ */
> diff --git a/net/netfilter/Kconfig b/net/netfilter/Kconfig
> index 32bff6d..3abd3a4 100644
> --- a/net/netfilter/Kconfig
> +++ b/net/netfilter/Kconfig
> @@ -483,6 +483,23 @@ config NETFILTER_XT_TARGET_IDLETIMER
>  
>  	  To compile it as a module, choose M here.  If unsure, say N.
>  
> +config NETFILTER_XT_TARGET_HMARK

New config option has to go in alphabetic order (this one should go
after NETFILTER_XT_TARGET_HL).

> +	tristate '"HMARK" target support'
> +	depends on NETFILTER_ADVANCED
> +	---help---
> +	This option adds the "HMARK" target.
> +
> +	The target allows you to create rules in the "raw" and "mangle" tables
> +	which alter the netfilter mark (nfmark) field within a given range.
> +	First a 32 bit hash value is generated then modulus by <limit> and
> +	finally an offset is added before it's written to nfmark.
> +
> +	Prior to routing, the nfmark can influence the routing method (see
> +	"Use netfilter MARK value as routing key") and can also be used by
> +	other subsystems to change their behavior.
> +
> +	The mark match can also be used to match nfmark produced by this module.
> +
>  config NETFILTER_XT_TARGET_LED
>  	tristate '"LED" target support'
>  	depends on LEDS_CLASS && LEDS_TRIGGERS
> diff --git a/net/netfilter/Makefile b/net/netfilter/Makefile
> index 1a02853..359eeb6 100644
> --- a/net/netfilter/Makefile
> +++ b/net/netfilter/Makefile
> @@ -56,6 +56,7 @@ obj-$(CONFIG_NETFILTER_XT_TARGET_CONNSECMARK) += xt_CONNSECMARK.o
>  obj-$(CONFIG_NETFILTER_XT_TARGET_CT) += xt_CT.o
>  obj-$(CONFIG_NETFILTER_XT_TARGET_DSCP) += xt_DSCP.o
>  obj-$(CONFIG_NETFILTER_XT_TARGET_HL) += xt_HL.o
> +obj-$(CONFIG_NETFILTER_XT_TARGET_HMARK) += xt_hmark.o
>  obj-$(CONFIG_NETFILTER_XT_TARGET_LED) += xt_LED.o
>  obj-$(CONFIG_NETFILTER_XT_TARGET_NFLOG) += xt_NFLOG.o
>  obj-$(CONFIG_NETFILTER_XT_TARGET_NFQUEUE) += xt_NFQUEUE.o
> diff --git a/net/netfilter/xt_hmark.c b/net/netfilter/xt_hmark.c
> new file mode 100644
> index 0000000..2f0aa93
> --- /dev/null
> +++ b/net/netfilter/xt_hmark.c
> @@ -0,0 +1,320 @@
> +/*
> + *	xt_hmark - Netfilter module to set mark as hash value
> + *
> + *	(C) 2010 Hans Schillstrom <hans.schillstrom@ericsson.com>
> + *
> + *	Description:
> + *	This module calculates a hash value that can be modified by modulus
> + *	and an offset. The hash value is based on a direction independent
> + *	five tuple: src & dst addr src & dst ports and protocol.
> + *	However src & dst port can be masked and are not used for fragmented
> + *	packets, ESP and AH don't have ports so SPI will be used instead.
> + *	For ICMP error messages the hash mark values will be calculated on
> + *	the source packet i.e. the packet caused the error (If sufficient
> + *	amount of data exists).
> + *
> + *	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/skbuff.h>
> +#include <net/ip.h>
> +#include <linux/icmp.h>
> +
> +#include <linux/netfilter/xt_hmark.h>
> +#include <linux/netfilter/x_tables.h>
> +#include <net/netfilter/nf_nat.h>
> +
> +#if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
> +#	define WITH_IPV6 1
> +#include <net/ipv6.h>
> +#include <linux/netfilter_ipv6/ip6_tables.h>
> +#endif
> +
> +

extra space not required.

> +MODULE_LICENSE("GPL");
> +MODULE_AUTHOR("Hans Schillstrom <hans.schillstrom@ericsson.com>");
> +MODULE_DESCRIPTION("Xtables: packet range mark operations by hash value");
> +MODULE_ALIAS("ipt_HMARK");
> +MODULE_ALIAS("ip6t_HMARK");
> +
> +/*
> + * ICMP, get inner header so calc can be made on the source message
> + *       not the icmp header, i.e. same hash mark must be produced
> + *       on an icmp error message.
> + */
> +static int get_inner_hdr(struct sk_buff *skb, int iphsz, int nhoff)

This looks very similar to icmp_error in nf_conntrack_proto_icmp.c.
Yours lacks of checksumming validation btw.

I'm trying to find some place where we can put this function to make
it available for both nf_conntrack_ipv4 and your module (to avoid code
redundancy), but I didn't find any so far.

It would be nice to find some way to avoid duplicating code with
similar functionality.

> +{
> +	const struct icmphdr *icmph;
> +	struct icmphdr _ih;
> +	struct iphdr *iph = NULL;
> +
> +	/* Not enough header? */
> +	icmph = skb_header_pointer(skb, nhoff + iphsz, sizeof(_ih), &_ih);
> +	if (icmph == NULL)
> +		goto out;
> +
> +	if (icmph->type > NR_ICMP_TYPES)
> +		goto out;
> +
> +

extra space not required.

> +	/* Error message? */
> +	if (icmph->type != ICMP_DEST_UNREACH &&
> +	    icmph->type != ICMP_SOURCE_QUENCH &&
> +	    icmph->type != ICMP_TIME_EXCEEDED &&
> +	    icmph->type != ICMP_PARAMETERPROB &&
> +	    icmph->type != ICMP_REDIRECT)
> +		goto out;
> +	/* Checkin full IP header plus 8 bytes of protocol to
> +	 * avoid additional coding at protocol handlers.
> +	 */
> +	if (!pskb_may_pull(skb, nhoff + iphsz + sizeof(_ih) + 8))
> +		goto out;

We prefer skb_header_pointer instead. If conntrack is enabled, we can
benefit from defragmention. Please, replace all pskb_may_pull by
skb_header_pointer in this code.

We can assume that the IP header is linear (not fragmented).

> +	iph = (struct iphdr *)(skb->data + nhoff + iphsz + sizeof(_ih));
> +	return nhoff + iphsz + sizeof(_ih);
> +out:
> +	return nhoff;
> +}
> +/*
> + * ICMPv6
> + * Input nhoff Offset into network header
> + *       offset where ICMPv6 header starts
> + * Returns true if it's a icmp error and updates nhoff
> + */
> +#ifdef WITH_IPV6
> +static int get_inner6_hdr(struct sk_buff *skb, int *offset, int hdrlen)
> +{
> +	struct icmp6hdr *icmp6h;
> +	struct icmp6hdr _ih6;
> +
> +	icmp6h = skb_header_pointer(skb, *offset + hdrlen, sizeof(_ih6), &_ih6);
> +	if (icmp6h == NULL)
> +		goto out;
> +
> +	if (icmp6h->icmp6_type && icmp6h->icmp6_type < 128) {
> +		*offset += hdrlen + sizeof(_ih6);
> +		return 1;
> +	}
> +out:
> +	return 0;
> +}
> +#endif
> +
> +/*
> + * Calc hash value, special casre is taken on icmp and fragmented messages
> + * i.e. fragmented messages don't use ports.
> + */
> +static __u32 get_hash(struct sk_buff *skb, struct xt_hmark_info *info)

This function seems to big to me, please, split it into smaller
chunks, like get_hash_ipv4, get_hash_ipv6 and get_hash_ports.

> +{
> +	int nhoff, hash = 0, poff, proto, frag = 0;
> +	struct iphdr *ip;
> +	u8 ip_proto;
> +	u32 addr1, addr2, ihl;
> +	u16 snatport = 0, dnatport = 0;
> +	union {
> +		u32 v32;
> +		u16 v16[2];
> +	} ports;
> +
> +	nhoff = skb_network_offset(skb);
> +	proto = skb->protocol;
> +
> +	if (!proto && skb->sk) {
> +		if (skb->sk->sk_family == AF_INET)
> +			proto = __constant_htons(ETH_P_IP);
> +		else if (skb->sk->sk_family == AF_INET6)
> +			proto = __constant_htons(ETH_P_IPV6);

You already have the layer3 protocol number in xt_action_param. No
need to use the socket information then.

> +	}
> +
> +	switch (proto) {
> +	case __constant_htons(ETH_P_IP):
> +	{
> +		enum ip_conntrack_info ctinfo;
> +		struct nf_conn *ct = ct = nf_ct_get(skb, &ctinfo);
> +		struct nf_conntrack_tuple *otuple, *rtuple;
> +
> +		if (!pskb_may_pull(skb, sizeof(*ip) + nhoff))
> +			goto done;
> +
> +		ip = (struct iphdr *) (skb->data + nhoff);
> +		if (ip->protocol == IPPROTO_ICMP) {
> +			/* Switch hash calc to inner header ? */
> +			nhoff = get_inner_hdr(skb, ip->ihl * 4, nhoff);
> +			ip = (struct iphdr *) (skb->data + nhoff);
> +		}
> +
> +		if (ip->frag_off & htons(IP_MF | IP_OFFSET))
> +			frag = 1;
> +
> +		ip_proto = ip->protocol;
> +		ihl = ip->ihl;
> +		addr1 = (__force u32) ip->saddr & info->smask;
> +		addr2 = (__force u32) ip->daddr & info->dmask;
> +
> +		if (!ct || !nf_ct_is_confirmed(ct))

You seem to (ab)use nf_ct_is_confirmed to make sure you're not in the
original direction. Better use the direction that you get by means of
nf_ct_get.

> +			break;
> +		otuple = &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple;
> +		/* On the "return flow", to get the original address
> +		 * i,e, replace the source address.
> +		 */
> +		if (ct->status & IPS_DST_NAT &&
> +		    info->flags & XT_HMARK_USE_DNAT) {
> +			rtuple = &ct->tuplehash[IP_CT_DIR_REPLY].tuple;
> +			addr1 = (__force u32) otuple->dst.u3.in.s_addr;
> +			dnatport = otuple->dst.u.udp.port;
> +		}
> +		/* On the "return flow", to get the original address
> +		 * i,e, replace the destination address.
> +		 */
> +		if (ct->status & IPS_SRC_NAT &&
> +		    info->flags & XT_HMARK_USE_SNAT) {
> +			rtuple = &ct->tuplehash[IP_CT_DIR_REPLY].tuple;
> +			addr2 = (__force u32) otuple->src.u3.in.s_addr;
> +			snatport = otuple->src.u.udp.port;
> +		}
> +		break;
> +	}
> +#ifdef WITH_IPV6
> +	case __constant_htons(ETH_P_IPV6):
> +	{
> +		struct ipv6hdr *ip6;	/* ip hdr */
> +		int hdrlen = 0;	/* In ip header */
> +		u8 nexthdr;
> +		int ip6hdrlvl = 0;	/* Header level */
> +		struct ipv6_opt_hdr _hdr, *hp;
> +
> +hdr_new:
> +		if (!pskb_may_pull(skb, sizeof(*ip6) + nhoff))
> +			goto done;
> +
> +		/* ip header */
> +		ip6 = (struct ipv6hdr *) (skb->data + nhoff);
> +		nexthdr = ip6->nexthdr;
> +		/* nhoff += sizeof(struct ipv6hdr);  Where hdr starts */
> +		hdrlen = sizeof(struct ipv6hdr);
> +		hp = skb_header_pointer(skb, nhoff + hdrlen, sizeof(_hdr),
> +					&_hdr);
> +		while (nexthdr) {
> +			switch (nexthdr) {
> +			case IPPROTO_ICMPV6:
> +				/* ICMP Error then move ptr to inner header */
> +				if (get_inner6_hdr(skb, &nhoff, hdrlen)) {
> +					ip6hdrlvl++;
> +					goto hdr_new;
> +				}
> +				nhoff += hdrlen;
> +				goto hdr_rdy;
> +
> +			case NEXTHDR_FRAGMENT:
> +				if (!ip6hdrlvl)
> +					frag = 1;
> +				break;
> +			/* End of hdr traversing */
> +			case NEXTHDR_IPV6:	/* Do not process tunnels */
> +			case NEXTHDR_TCP:
> +			case NEXTHDR_UDP:
> +			case NEXTHDR_ESP:
> +			case NEXTHDR_AUTH:
> +			case NEXTHDR_NONE:
> +				nhoff += hdrlen;
> +				goto hdr_rdy;
> +			default:
> +				goto done;

This goto doesn't make too much sense to me, better return 0.

> +			}
> +			if (!hp)
> +				goto done;
> +			nhoff += hdrlen;	/* eat current header */
> +			nexthdr =  hp->nexthdr;	/* Next header */
> +			hdrlen = ipv6_optlen(hp);
> +			hp = skb_header_pointer(skb, nhoff + hdrlen,
> +						sizeof(_hdr), &_hdr);
> +
> +			if (!pskb_may_pull(skb, nhoff))
> +				goto done;
> +		}
> +hdr_rdy:
> +		ip_proto = nexthdr;
> +
> +		addr1 = (__force u32) ip6->saddr.s6_addr32[3];
> +		addr2 = (__force u32) ip6->daddr.s6_addr32[3];
> +		ihl = 0; /* (40 >> 2); */
> +		break;
> +	}
> +#endif
> +	default:
> +		goto done;
> +	}
> +
> +	ports.v32 = 0;
> +	poff = proto_ports_offset(ip_proto);
> +	nhoff += ihl * 4 + poff;
> +	if (!frag && poff >= 0 && pskb_may_pull(skb, nhoff + 4)) {
> +		ports.v32 = * (__force u32 *) (skb->data + nhoff);
> +		if (ip_proto == IPPROTO_ESP || ip_proto == IPPROTO_AH) {
> +			ports.v32 = (ports.v32 & info->spimask) | info->spiset;
> +		} else { /* Handle endian */
> +			if (snatport)	/* Replace snated dst port (ret flow) */
> +				ports.v16[1] = snatport;
> +			if (dnatport)
> +				ports.v16[0] = dnatport;
> +			ports.v32 = (ports.v32 & info->pmask.v32) |
> +				    info->pset.v32;
> +			if (ports.v16[1] < ports.v16[0])
> +				swap(ports.v16[0], ports.v16[1]);
> +		}
> +	}
> +	ip_proto &= info->prmask;
> +	/* get a consistent hash (same value on both flow directions) */
> +	if (addr2 < addr1)
> +		swap(addr1, addr2);
> +
> +	hash = jhash_3words(addr1, addr2, ports.v32, info->hashrnd) ^ ip_proto;
> +	if (!hash)
> +		hash = 1;
> +
> +	return hash;
> +
> +done:
> +	return 0;
> +}

I'll try to find more time to look into this. Specifically, I want to
review the IPv6 bits more carefully.

Re: [v2 PATCH 2/2] NETFILTER userspace part for target HMARK

[Pablo Neira Ayuso]

On Mon, Oct 03, 2011 at 07:46:43PM +0200, Hans Schillstrom wrote:
> The target allows you to create rules in the "raw" and "mangle" tables
> which alter the netfilter mark (nfmark) field within a given range.
> First a 32 bit hash value is generated then modulus by <limit> and
> finally an offset is added before it's written to nfmark.
> Prior to routing, the nfmark can influence the routing method (see
> "Use netfilter MARK value as routing key") and can also be used by
> other subsystems to change their behaviour.
> 
> The mark match can also be used to match nfmark produced by this module.
> 
> Ver 2
>   IPv4 NAT added
>   iptables ver 1.4.12.1 adaptions.
> 
> Signed-off-by: Hans Schillstrom <hans.schillstrom@ericsson.com>
> ---
>  extensions/libxt_HMARK.c           |  381 ++++++++++++++++++++++++++++++++++++
>  extensions/libxt_HMARK.man         |   66 ++++++
>  include/linux/netfilter/xt_hmark.h |   48 +++++
>  3 files changed, 495 insertions(+), 0 deletions(-)
>  create mode 100644 extensions/libxt_HMARK.c
>  create mode 100644 extensions/libxt_HMARK.man
>  create mode 100644 include/linux/netfilter/xt_hmark.h
> 
> diff --git a/extensions/libxt_HMARK.c b/extensions/libxt_HMARK.c
> new file mode 100644
> index 0000000..0def034
> --- /dev/null
> +++ b/extensions/libxt_HMARK.c
> @@ -0,0 +1,381 @@
> +/*
> + * Shared library add-on to iptables to add HMARK target support.
> + *
> + * The kernel module calculates a hash value that can be modified by modulus
> + * and an offset. The hash value is based on a direction independent
> + * five tuple: src & dst addr src & dst ports and protocol.
> + * However src & dst port can be masked and are not used for fragmented
> + * packets, ESP and AH don't have ports so SPI will be used instead.
> + * For ICMP error messages the hash mark values will be calculated on
> + * the source packet i.e. the packet caused the error (If sufficient
> + * amount of data exists).
> + * 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 <stdbool.h>
> +#include <stdio.h>
> +#include <string.h>
> +#include <stdlib.h>
> +#include <getopt.h>
> +
> +#include <xtables.h>
> +#include <linux/netfilter/x_tables.h>
> +#include <linux/netfilter/xt_hmark.h>
> +
> +
> +#define DEF_HRAND 0xc175a3b8	/* Default "random" value to jhash */
> +
> +static void HMARK_help(void)
> +{
> +	printf(
> +"HMARK target options, i.e. modify hash calculation by:\n"
> +"  --hmark-smask value                Mask source address with value\n"
> +"  --hmark-dmask value                Mask Dest. address with value\n"
> +"  --hmark-sp-mask value              Mask src port with value\n"
> +"  --hmark-dp-mask value              Mask dst port with value\n"
> +"  --hmark-spi-mask value             For esp and ah AND spi with value\n"
> +"  --hmark-sp-set value               OR src port with value\n"
> +"  --hmark-dp-set value               OR dst port with value\n"
> +"  --hmark-spi-set value              For esp and ah OR spi with value\n"
> +"  --hmark-proto-mask value           Mask Protocol with value\n"
> +"  --hmark-rnd                        Random value to hash cacl.\n"
> +"  Limit/modify the calculated hash mark by:\n"
> +"  --hmark-mod value                  nfmark modulus value\n"
> +"  --hmark-offs value                 Last action add value to nfmark\n"
> +" For NAT in IPv4 the original address can be used in the return path.\n"
> +" Make sure to qualify the statement in a proper way when using nat flags\n"
> +"  --hmark-dnat                       Replace src addr/port with original dst addr/port\n"
> +"  --hmark-snat                       Replace dst addr/port with original src addr/port\n"
> +" In many cases hmark can be omitted i.e. --smask can be used\n");
> +}
> +
> +static const struct option HMARK_opts[] = {
> +	{ "hmark-smask", 1, NULL, XT_HMARK_SADR_AND },
> +	{ "hmark-dmask", 1, NULL, XT_HMARK_DADR_AND },
> +	{ "hmark-sp-mask", 1, NULL, XT_HMARK_SPORT_AND },
> +	{ "hmark-dp-mask", 1, NULL, XT_HMARK_DPORT_AND },
> +	{ "hmark-spi-mask", 1, NULL, XT_HMARK_SPI_AND },
> +	{ "hmark-sp-set", 1, NULL, XT_HMARK_SPORT_OR },
> +	{ "hmark-dp-set", 1, NULL, XT_HMARK_DPORT_OR },
> +	{ "hmark-spi-set", 1, NULL, XT_HMARK_SPI_OR },
> +	{ "hmark-proto-mask", 1, NULL, XT_HMARK_PROTO_AND },
> +	{ "hmark-rnd", 1, NULL, XT_HMARK_RND },
> +	{ "hmark-mod", 1, NULL, XT_HMARK_MODULUS },
> +	{ "hmark-offs", 1, NULL, XT_HMARK_OFFSET },
> +	{ "hmark-dnat", 1, NULL, XT_HMARK_USE_DNAT },
> +	{ "hmark-snat", 1, NULL, XT_HMARK_USE_SNAT },
> +	{ "smask", 1, NULL, XT_HMARK_SADR_AND },
> +	{ "dmask", 1, NULL, XT_HMARK_DADR_AND },
> +	{ "sp-mask", 1, NULL, XT_HMARK_SPORT_AND },
> +	{ "dp-mask", 1, NULL, XT_HMARK_DPORT_AND },
> +	{ "spi-mask", 1, NULL, XT_HMARK_SPI_AND },
> +	{ "sp-set", 1, NULL, XT_HMARK_SPORT_OR },
> +	{ "dp-set", 1, NULL, XT_HMARK_DPORT_OR },
> +	{ "spi-set", 1, NULL, XT_HMARK_SPI_OR },
> +	{ "proto-mask", 1, NULL, XT_HMARK_PROTO_AND },
> +	{ "rnd", 1, NULL, XT_HMARK_RND },
> +	{ "mod", 1, NULL, XT_HMARK_MODULUS },
> +	{ "offs", 1, NULL, XT_HMARK_OFFSET },
> +	{ "dnat", 1, NULL, XT_HMARK_USE_DNAT },
> +	{ "snat", 1, NULL, XT_HMARK_USE_SNAT },
> +	{ .name = NULL }
> +};
> +
> +static int
> +HMARK_parse(int c, char **argv, int invert, unsigned int *flags,
> +	    const void *entry, struct xt_entry_target **target)
> +{
> +	struct xt_hmark_info *hmarkinfo
> +		= (struct xt_hmark_info *)(*target)->data;
> +	unsigned int value = 0xffffffff;
> +	unsigned int maxint = UINT32_MAX;
> +
> +	if ((c < XT_HMARK_SADR_AND) || (c > XT_HMARK_OFFSET)) {
> +		xtables_error(PARAMETER_PROBLEM, "Bad HMARK option \"%s\"",
> +			      optarg);
> +		return 0;
> +	}
> +
> +	if (c >= XT_HMARK_SPORT_AND && c <= XT_HMARK_DPORT_OR)
> +		maxint = UINT16_MAX;
> +	else if (c == XT_HMARK_PROTO_AND)
> +		maxint = UINT8_MAX;
> +
> +	if (!xtables_strtoui(optarg, NULL, &value, 0, maxint))
> +		xtables_error(PARAMETER_PROBLEM, "Bad HMARK value \"%s\"",
> +			      optarg);
> +
> +	if (*flags == 0) {
> +		memset(hmarkinfo, 0xff, sizeof(struct xt_hmark_info));
> +		hmarkinfo->pset.v32 = 0;
> +		hmarkinfo->flags = 0;
> +		hmarkinfo->spiset = 0;
> +		hmarkinfo->hoffs = 0;
> +		hmarkinfo->hashrnd = DEF_HRAND;
> +	}
> +	switch (c) {
> +	case XT_HMARK_SADR_AND:
> +		if (*flags & (1 << c)) {
> +			xtables_error(PARAMETER_PROBLEM,
> +				      "Can only specify "
> +				      "`--hmark-smask' once");
> +		}
> +		hmarkinfo->smask = htonl(value);
> +		if (value == maxint)
> +			c = 0;
> +		break;

Please, check current iptables git tree. Jan implemented more advanced
method to handle options. For instance, have a look at libxt_cluster.c

Re: [v2 PATCH 1/2] NETFILTER module xt_hmark new target for HASH based fw

[Jan Engelhardt]

On Monday 2011-11-07 01:52, Pablo Neira Ayuso wrote:
>> +static __u32 get_hash(struct sk_buff *skb, struct xt_hmark_info *info)
>> +{
>> +	int nhoff, hash = 0, poff, proto, frag = 0;
>> +	struct iphdr *ip;
>> +	u8 ip_proto;
>> +	u32 addr1, addr2, ihl;
>> +	u16 snatport = 0, dnatport = 0;
>> +	union {
>> +		u32 v32;
>> +		u16 v16[2];
>> +	} ports;
>> +
>> +	nhoff = skb_network_offset(skb);
>> +	proto = skb->protocol;
>> +
>> +	if (!proto && skb->sk) {
>> +		if (skb->sk->sk_family == AF_INET)
>> +			proto = __constant_htons(ETH_P_IP);
>> +		else if (skb->sk->sk_family == AF_INET6)
>> +			proto = __constant_htons(ETH_P_IPV6);
>
>You already have the layer3 protocol number in xt_action_param. No
>need to use the socket information then.

xt_action_param.family (NFPROTO_) is not the same class af AF_ or ETH_.
Though, wouldn't proto = skb->proto; just be simpler here?

[v2 PATCH 2/2] NETFILTER userspace part for target HMARK

[Hans Schillstrom]

The target allows you to create rules in the "raw" and "mangle" tables
which alter the netfilter mark (nfmark) field within a given range.
First a 32 bit hash value is generated then modulus by <limit> and
finally an offset is added before it's written to nfmark.
Prior to routing, the nfmark can influence the routing method (see
"Use netfilter MARK value as routing key") and can also be used by
other subsystems to change their behaviour.

The mark match can also be used to match nfmark produced by this module.

Ver 2
  IPv4 NAT added
  iptables ver 1.4.12.1 adaptions.

Signed-off-by: Hans Schillstrom <hans.schillstrom@ericsson.com>
---
 extensions/libxt_HMARK.c           |  381 ++++++++++++++++++++++++++++++++++++
 extensions/libxt_HMARK.man         |   66 ++++++
 include/linux/netfilter/xt_hmark.h |   48 +++++
 3 files changed, 495 insertions(+), 0 deletions(-)
 create mode 100644 extensions/libxt_HMARK.c
 create mode 100644 extensions/libxt_HMARK.man
 create mode 100644 include/linux/netfilter/xt_hmark.h

diff --git a/extensions/libxt_HMARK.c b/extensions/libxt_HMARK.c
new file mode 100644
index 0000000..0def034
--- /dev/null
+++ b/extensions/libxt_HMARK.c
@@ -0,0 +1,381 @@
+/*
+ * Shared library add-on to iptables to add HMARK target support.
+ *
+ * The kernel module calculates a hash value that can be modified by modulus
+ * and an offset. The hash value is based on a direction independent
+ * five tuple: src & dst addr src & dst ports and protocol.
+ * However src & dst port can be masked and are not used for fragmented
+ * packets, ESP and AH don't have ports so SPI will be used instead.
+ * For ICMP error messages the hash mark values will be calculated on
+ * the source packet i.e. the packet caused the error (If sufficient
+ * amount of data exists).
+ * 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 <stdbool.h>
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+#include <getopt.h>
+
+#include <xtables.h>
+#include <linux/netfilter/x_tables.h>
+#include <linux/netfilter/xt_hmark.h>
+
+
+#define DEF_HRAND 0xc175a3b8	/* Default "random" value to jhash */
+
+static void HMARK_help(void)
+{
+	printf(
+"HMARK target options, i.e. modify hash calculation by:\n"
+"  --hmark-smask value                Mask source address with value\n"
+"  --hmark-dmask value                Mask Dest. address with value\n"
+"  --hmark-sp-mask value              Mask src port with value\n"
+"  --hmark-dp-mask value              Mask dst port with value\n"
+"  --hmark-spi-mask value             For esp and ah AND spi with value\n"
+"  --hmark-sp-set value               OR src port with value\n"
+"  --hmark-dp-set value               OR dst port with value\n"
+"  --hmark-spi-set value              For esp and ah OR spi with value\n"
+"  --hmark-proto-mask value           Mask Protocol with value\n"
+"  --hmark-rnd                        Random value to hash cacl.\n"
+"  Limit/modify the calculated hash mark by:\n"
+"  --hmark-mod value                  nfmark modulus value\n"
+"  --hmark-offs value                 Last action add value to nfmark\n"
+" For NAT in IPv4 the original address can be used in the return path.\n"
+" Make sure to qualify the statement in a proper way when using nat flags\n"
+"  --hmark-dnat                       Replace src addr/port with original dst addr/port\n"
+"  --hmark-snat                       Replace dst addr/port with original src addr/port\n"
+" In many cases hmark can be omitted i.e. --smask can be used\n");
+}
+
+static const struct option HMARK_opts[] = {
+	{ "hmark-smask", 1, NULL, XT_HMARK_SADR_AND },
+	{ "hmark-dmask", 1, NULL, XT_HMARK_DADR_AND },
+	{ "hmark-sp-mask", 1, NULL, XT_HMARK_SPORT_AND },
+	{ "hmark-dp-mask", 1, NULL, XT_HMARK_DPORT_AND },
+	{ "hmark-spi-mask", 1, NULL, XT_HMARK_SPI_AND },
+	{ "hmark-sp-set", 1, NULL, XT_HMARK_SPORT_OR },
+	{ "hmark-dp-set", 1, NULL, XT_HMARK_DPORT_OR },
+	{ "hmark-spi-set", 1, NULL, XT_HMARK_SPI_OR },
+	{ "hmark-proto-mask", 1, NULL, XT_HMARK_PROTO_AND },
+	{ "hmark-rnd", 1, NULL, XT_HMARK_RND },
+	{ "hmark-mod", 1, NULL, XT_HMARK_MODULUS },
+	{ "hmark-offs", 1, NULL, XT_HMARK_OFFSET },
+	{ "hmark-dnat", 1, NULL, XT_HMARK_USE_DNAT },
+	{ "hmark-snat", 1, NULL, XT_HMARK_USE_SNAT },
+	{ "smask", 1, NULL, XT_HMARK_SADR_AND },
+	{ "dmask", 1, NULL, XT_HMARK_DADR_AND },
+	{ "sp-mask", 1, NULL, XT_HMARK_SPORT_AND },
+	{ "dp-mask", 1, NULL, XT_HMARK_DPORT_AND },
+	{ "spi-mask", 1, NULL, XT_HMARK_SPI_AND },
+	{ "sp-set", 1, NULL, XT_HMARK_SPORT_OR },
+	{ "dp-set", 1, NULL, XT_HMARK_DPORT_OR },
+	{ "spi-set", 1, NULL, XT_HMARK_SPI_OR },
+	{ "proto-mask", 1, NULL, XT_HMARK_PROTO_AND },
+	{ "rnd", 1, NULL, XT_HMARK_RND },
+	{ "mod", 1, NULL, XT_HMARK_MODULUS },
+	{ "offs", 1, NULL, XT_HMARK_OFFSET },
+	{ "dnat", 1, NULL, XT_HMARK_USE_DNAT },
+	{ "snat", 1, NULL, XT_HMARK_USE_SNAT },
+	{ .name = NULL }
+};
+
+static int
+HMARK_parse(int c, char **argv, int invert, unsigned int *flags,
+	    const void *entry, struct xt_entry_target **target)
+{
+	struct xt_hmark_info *hmarkinfo
+		= (struct xt_hmark_info *)(*target)->data;
+	unsigned int value = 0xffffffff;
+	unsigned int maxint = UINT32_MAX;
+
+	if ((c < XT_HMARK_SADR_AND) || (c > XT_HMARK_OFFSET)) {
+		xtables_error(PARAMETER_PROBLEM, "Bad HMARK option \"%s\"",
+			      optarg);
+		return 0;
+	}
+
+	if (c >= XT_HMARK_SPORT_AND && c <= XT_HMARK_DPORT_OR)
+		maxint = UINT16_MAX;
+	else if (c == XT_HMARK_PROTO_AND)
+		maxint = UINT8_MAX;
+
+	if (!xtables_strtoui(optarg, NULL, &value, 0, maxint))
+		xtables_error(PARAMETER_PROBLEM, "Bad HMARK value \"%s\"",
+			      optarg);
+
+	if (*flags == 0) {
+		memset(hmarkinfo, 0xff, sizeof(struct xt_hmark_info));
+		hmarkinfo->pset.v32 = 0;
+		hmarkinfo->flags = 0;
+		hmarkinfo->spiset = 0;
+		hmarkinfo->hoffs = 0;
+		hmarkinfo->hashrnd = DEF_HRAND;
+	}
+	switch (c) {
+	case XT_HMARK_SADR_AND:
+		if (*flags & (1 << c)) {
+			xtables_error(PARAMETER_PROBLEM,
+				      "Can only specify "
+				      "`--hmark-smask' once");
+		}
+		hmarkinfo->smask = htonl(value);
+		if (value == maxint)
+			c = 0;
+		break;
+
+	case XT_HMARK_DADR_AND:
+		if (*flags & (1 << c)) {
+			xtables_error(PARAMETER_PROBLEM,
+				      "Can only specify "
+				      "`--hmark-dmask' once");
+		}
+		hmarkinfo->dmask = htonl(value);
+		if (value == maxint)
+			c = 0;
+		break;
+
+	case XT_HMARK_MODULUS:
+		if (*flags & (1 << c)) {
+			xtables_error(PARAMETER_PROBLEM,
+				      "Can only specify "
+				      "`--hmark-mod' once");
+		}
+		if (value == 0) {
+			xtables_error(PARAMETER_PROBLEM,
+				      "xxx modulus 0 ? "
+				      "thats a div by 0");
+			value = 0xffffffff;
+		}
+		hmarkinfo->hmod = value;
+		if (value == maxint)
+			c = 0;
+		break;
+
+	case XT_HMARK_OFFSET:
+		if (*flags & (1 << c)) {
+			xtables_error(PARAMETER_PROBLEM,
+				      "Can only specify "
+				      "`--hmark-offs' once");
+		}
+		hmarkinfo->hoffs = value;
+		if (value == 0)
+			c = 0;
+		break;
+
+	case XT_HMARK_SPORT_AND:
+		if (*flags & (1 << c)) {
+			xtables_error(PARAMETER_PROBLEM,
+				      "Can only specify "
+				      "`--hmark-sp-mask' once");
+		}
+		hmarkinfo->pmask.p16.src = htons(value);
+		if (value == maxint)
+			c = 0;
+		break;
+
+	case XT_HMARK_DPORT_AND:
+		if (*flags & (1 << c)) {
+			xtables_error(PARAMETER_PROBLEM,
+				      "Can only specify "
+				      "`--hmark-dp-mask' once");
+		}
+		hmarkinfo->pmask.p16.dst = htons(value);
+		if (value == maxint)
+			c = 0;
+		break;
+
+	case XT_HMARK_SPI_AND:
+		if (*flags & (1 << c)) {
+			xtables_error(PARAMETER_PROBLEM,
+				      "Can only specify "
+				      "`--hmark-spi-mask' once");
+		}
+		hmarkinfo->spimask = htonl(value);
+		if (value == maxint)
+			c = 0;
+		break;
+
+	case XT_HMARK_SPORT_OR:
+		if (*flags & (1 << c)) {
+			xtables_error(PARAMETER_PROBLEM,
+				      "Can only specify "
+				      "`--hmark-sp-set' once");
+		}
+		hmarkinfo->pset.p16.src = htons(value);
+		if (!value)
+			c = 0;
+		break;
+
+	case XT_HMARK_DPORT_OR:
+		if (*flags & (1 << c)) {
+			xtables_error(PARAMETER_PROBLEM,
+				      "Can only specify "
+				      "`--hmark-dp-set' once");
+		}
+		hmarkinfo->pset.p16.dst = htons(value);
+		if (!value)
+			c = 0;
+		break;
+
+	case XT_HMARK_SPI_OR:
+		if (*flags & (1 << c)) {
+			xtables_error(PARAMETER_PROBLEM,
+				      "Can only specify "
+				      "`--hmark-spi-set' once");
+		}
+		hmarkinfo->spiset = htonl(value);
+		if (!value)
+			c = 0;
+		break;
+
+	case XT_HMARK_PROTO_AND:
+		if (*flags & (1 << c)) {
+			xtables_error(PARAMETER_PROBLEM,
+				      "Can only specify "
+				      "`--hmark-proto-mask' once");
+		}
+		hmarkinfo->prmask = value;
+		if (value == maxint)
+			c = 0;
+		break;
+
+	case XT_HMARK_RND:
+		if (*flags & (1 << c)) {
+			xtables_error(PARAMETER_PROBLEM,
+				      "Can only specify `--hmark-rnd' once");
+		}
+		hmarkinfo->hashrnd = value;
+		if (value == DEF_HRAND)
+			c = 0;
+		break;
+
+	case XT_HMARK_USE_DNAT:
+		if (*flags & (1 << c)) {
+			xtables_error(PARAMETER_PROBLEM,
+				      "Can only specify `--hmark-rnd' once");
+		}
+		break;
+
+	case XT_HMARK_USE_SNAT:
+		if (*flags & (1 << c)) {
+			xtables_error(PARAMETER_PROBLEM,
+				      "Can only specify `--hmark-rnd' once");
+		}
+		break;
+
+	default:
+		return 0;
+	}
+	*flags |= 1 << c;
+	hmarkinfo->flags = *flags;
+
+	return 1;
+}
+
+static void HMARK_check(unsigned int flags)
+{
+	if (!(flags & (1 << XT_HMARK_MODULUS)))
+		xtables_error(PARAMETER_PROBLEM, "HMARK: the --hmark-mod, "
+			   "is not set, that means the nfmark will be in range"
+			   " 0 - 0xffffffff");
+}
+
+static void HMARK_print(const void *ip, const struct xt_entry_target *target,
+			int numeric)
+{
+	const struct xt_hmark_info *info =
+			(const struct xt_hmark_info *)target->data;
+
+	printf(" HMARK ");
+	if (info->flags & (1 << XT_HMARK_USE_SNAT))
+		printf("snat, ");
+	if (info->flags & (1 << XT_HMARK_SADR_AND))
+		printf("smask 0x%x ", htonl(info->smask));
+
+	if (info->flags & (1 << XT_HMARK_USE_DNAT))
+		printf("dnat, ");
+	if (info->flags & (1 << XT_HMARK_DADR_AND))
+		printf("dmask 0x%x ", htonl(info->dmask));
+
+	if (info->flags & (1 << XT_HMARK_SPORT_AND))
+		printf("sp-mask 0x%x ", htons(info->pmask.p16.src));
+	if (info->flags & (1 << XT_HMARK_DPORT_AND))
+		printf("dp-mask 0x%x ", htons(info->pmask.p16.dst));
+	if (info->flags & (1 << XT_HMARK_SPI_AND))
+		printf("spi-mask 0x%x ", htonl(info->spimask));
+	if (info->flags & (1 << XT_HMARK_SPORT_OR))
+		printf("sp-set 0x%x ", htons(info->pset.p16.src));
+	if (info->flags & (1 << XT_HMARK_DPORT_OR))
+		printf("dp-set 0x%x ", htons(info->pset.p16.dst));
+	if (info->flags & (1 << XT_HMARK_SPI_OR))
+		printf("spi-set 0x%x ", htonl(info->spiset));
+	if (info->flags & (1 << XT_HMARK_PROTO_AND))
+		printf("proto-mask 0x%x ", info->prmask);
+	if (info->flags & (1 << XT_HMARK_RND))
+		printf("rnd 0x%x ", info->hashrnd);
+	if (info->flags & (1 << XT_HMARK_MODULUS))
+		printf("mark=hv %% 0x%x ", info->hmod);
+	if (info->flags & (1 << XT_HMARK_OFFSET))
+		printf("+ 0x%x ", info->hoffs);
+}
+
+static void HMARK_save(const void *ip, const struct xt_entry_target *target)
+{
+	const struct xt_hmark_info *info =
+		(const struct xt_hmark_info *)target->data;
+
+	if (info->flags & (1 << XT_HMARK_SADR_AND))
+		printf("--hmark-smask 0x%x ", htonl(info->smask));
+	if (info->flags & (1 << XT_HMARK_DADR_AND))
+		printf("--hmark-dmask 0x%x ", htonl(info->dmask));
+	if (info->flags & (1 << XT_HMARK_SPORT_AND))
+		printf("--hmark-sp-mask 0x%x ", htons(info->pmask.p16.src));
+	if (info->flags & (1 << XT_HMARK_DPORT_AND))
+		printf("--hmark-dp-mask 0x%x ", htons(info->pmask.p16.dst));
+	if (info->flags & (1 << XT_HMARK_SPI_AND))
+		printf("--hmark-spi-mask 0x%x ", htonl(info->spimask));
+	if (info->flags & (1 << XT_HMARK_SPORT_OR))
+		printf("--hmark-sp-set 0x%x ", htons(info->pset.p16.src));
+	if (info->flags & (1 << XT_HMARK_DPORT_OR))
+		printf("--hmark-dp-set 0x%x ", htons(info->pset.p16.dst));
+	if (info->flags & (1 << XT_HMARK_SPI_OR))
+		printf("--hmark-spi-set 0x%x ", htonl(info->spiset));
+	if (info->flags & (1 << XT_HMARK_PROTO_AND))
+		printf("--hmark-proto-mask 0x%x ", info->prmask);
+	if (info->flags & (1 << XT_HMARK_RND))
+		printf("--hmark-rnd 0x%x ", info->hashrnd);
+	if (info->flags & (1 << XT_HMARK_MODULUS))
+		printf("--hmark-mod 0x%x ", info->hmod);
+	if (info->flags & (1 << XT_HMARK_OFFSET))
+		printf("--hmark-offs 0x%x ", info->hoffs);
+	if (info->flags & (1 << XT_HMARK_USE_DNAT))
+		printf("--hmark-dnat ");
+	if (info->flags & (1 << XT_HMARK_USE_SNAT))
+		printf("--hmark-snat ");
+}
+
+static struct xtables_target mark_tg_reg[] = {
+	{
+		.family        = NFPROTO_UNSPEC,
+		.name          = "HMARK",
+		.version       = XTABLES_VERSION,
+		.revision      = 0,
+		.size          = XT_ALIGN(sizeof(struct xt_hmark_info)),
+		.userspacesize = XT_ALIGN(sizeof(struct xt_hmark_info)),
+		.help          = HMARK_help,
+		.parse         = HMARK_parse,
+		.final_check   = HMARK_check,
+		.print         = HMARK_print,
+		.save          = HMARK_save,
+		.extra_opts    = HMARK_opts,
+	},
+};
+
+void _init(void)
+{
+	xtables_register_targets(mark_tg_reg, ARRAY_SIZE(mark_tg_reg));
+}
+
diff --git a/extensions/libxt_HMARK.man b/extensions/libxt_HMARK.man
new file mode 100644
index 0000000..8f44676
--- /dev/null
+++ b/extensions/libxt_HMARK.man
@@ -0,0 +1,66 @@
+This module does the same as MARK, i.e. set an fwmark, but the mark is based on a hash value.
+The hash is based on saddr, daddr, sport, dport and proto. The same mark will be produced independet of direction if no masks is set or the same masks is used for src and dest.
+The hash mark could be adjusted by modulus and finally an offset could be added, i.e the final mark will be within a range. If state RELATED is used icmp will be handled also, i.e. hash will be calculated on the original message not the icmp it self.
+Note: None of the parameters effect the packet it self only the calculated hash value.
+.PP
+Parameters:
+For all masks default is all "1:s", to disable a field use mask 0
+For IPv6 it's just the last 32 bits that is included in the hash
+.TP
+\fB\-\-hmark\-smask\fP \fIvalue\fP
+The value to AND the source address with (saddr & value).
+.TP
+\fB\-\-hmark\-dmask\fP \fIvalue\fP
+The value to AND the dest. address with (daddr & value).
+.TP
+\fB\-\-hmark\-sp\-mask\fP \fIvalue\fP
+A 16 bit value to AND the src port with (sport & value).
+.TP
+\fB\-\-hmark\-dp\-mask\fP \fIvalue\fP
+A 16 bit value to AND the dest port with (dport & value).
+.TP
+\fB\-\-hmark\-sp\-set\fP \fIvalue\fP
+A 16 bit value to OR the src port with (sport | value).
+.TP
+\fB\-\-hmark\-dp\-set\fP \fIvalue\fP
+A 16 bit value to OR the dest port with (dport | value).
+.TP
+\fB\-\-hmark\-spi\-mask\fP \fIvalue\fP
+Value to AND the spi field with (spi & value) valid for proto esp or ah.
+.TP
+\fB\-\-hmark\-spi\-set\fP \fIvalue\fP
+Value to OR the spi field with (spi | value) valid for proto esp or ah.
+.TP
+\fB\-\-hmark\-proto\-mask\fP \fIvalue\fP
+An 8 bit value to AND the L4 proto field with (proto & value).
+.TP
+\fB\-\-hmark\-rnd\fP \fIvalue\fP
+A 32 bit initial value for hash calc, default is 0xc175a3b8.
+.TP
+\fB\-\-hmark\-dnat\fP
+Replace src addr/port with original dst addr/port before calc, hash
+.TP
+\fB\-\-hmark\-dnat\fP
+Replace dst addr/port with original src addr/port before calc, hash
+.PP
+Final processing of the mark in order of execution.
+.TP
+\fB\-\-hmark\-mod\fP \fvalue (must be > 0)\fP
+The easiest way to describe this is:  hash = hash mod <value>
+.TP
+\fB\-\-hmark\-offs\fP \fvalue\fP
+The easiest way to describe this is:  hash = hash + <value>
+.PP
+\fIExamples:\fP
+.PP
+Default rule handles all TCP, UDP, SCTP, ESP & AH
+.IP
+iptables \-t mangle \-A PREROUTING \-m state \-\-state NEW,ESTABLISHED,RELATED
+ \-j HMARK \-\-hmark-offs 10000 \-\-hmark-mod 10
+.PP
+Handle SCTP and hash dest port only and produce a nfmark between 100-119.
+.IP
+iptables \-t mangle \-A PREROUTING -p SCTP \-j HMARK \-\-smask 0 \-\-dmask 0
+ \-\-sp\-mask 0 \-\-offs 100 \-\-mod 20
+.PP
+
diff --git a/include/linux/netfilter/xt_hmark.h b/include/linux/netfilter/xt_hmark.h
new file mode 100644
index 0000000..7b3ee5d
--- /dev/null
+++ b/include/linux/netfilter/xt_hmark.h
@@ -0,0 +1,48 @@
+#ifndef XT_HMARK_H_
+#define XT_HMARK_H_
+
+#include <linux/types.h>
+
+/*
+ * Flags must not start at 0, since it's used as none.
+ */
+enum {
+	XT_HMARK_USE_SNAT = 1,	/* SNAT & DNAT are used by the kernel module */
+	XT_HMARK_USE_DNAT,
+	XT_HMARK_SADR_AND,
+	XT_HMARK_DADR_AND,
+	XT_HMARK_SPI_AND,
+	XT_HMARK_SPI_OR,
+	XT_HMARK_SPORT_AND,
+	XT_HMARK_DPORT_AND,
+	XT_HMARK_SPORT_OR,
+	XT_HMARK_DPORT_OR,
+	XT_HMARK_PROTO_AND,
+	XT_HMARK_RND,
+	XT_HMARK_MODULUS,
+	XT_HMARK_OFFSET,
+};
+
+union ports {
+	struct {
+		__u16	src;
+		__u16	dst;
+	} p16;
+	__u32	v32;
+};
+
+struct xt_hmark_info {
+	__u32		smask;		/* Source address mask */
+	__u32		dmask;		/* Dest address mask */
+	union ports	pmask;
+	union ports	pset;
+	__u32		spimask;
+	__u32		spiset;
+	__u16		flags;		/* Print out only */
+	__u16		prmask;		/* L4 Proto mask */
+	__u32		hashrnd;
+	__u32		hmod;		/* Modulus */
+	__u32		hoffs;		/* Offset */
+};
+
+#endif /* XT_HMARK_H_ */
-- 
1.7.4.4