From: Thomas Graf <tgraf@redhat.com>
Date: Thu, 16 Apr 2009 19:24:06 +0200
Subject: [net] add DSCP netfilter target
Message-id: 20090416172406.GA13688@plip.localdomain
O-Subject: [RHEL5.4 PATCH] net: add DSCP netfilter target (bz481652)
Bugzilla: 481652
RH-Acked-by: David Miller <davem@redhat.com>
RH-Acked-by: Neil Horman <nhorman@redhat.com>

Hey all

This patch adds the netfilter target DSCP which allows the
manipulation of the DSCP field for both, IPv4 and IPv6 packets.

Fixes BZ481652. Please ACK

diff --git a/include/linux/netfilter/Kbuild b/include/linux/netfilter/Kbuild
index 9a285ce..5c4374a 100644
--- a/include/linux/netfilter/Kbuild
+++ b/include/linux/netfilter/Kbuild
@@ -29,6 +29,8 @@ header-y += xt_tcpmss.h
 header-y += xt_tcpudp.h
 header-y += xt_SECMARK.h
 header-y += xt_CONNSECMARK.h
+header-y += xt_DSCP.h
+header-y += xt_dscp.h
 
 unifdef-y += nf_conntrack_common.h
 unifdef-y += nf_conntrack_ftp.h
diff --git a/include/linux/netfilter/xt_DSCP.h b/include/linux/netfilter/xt_DSCP.h
new file mode 100644
index 0000000..80bd325
--- /dev/null
+++ b/include/linux/netfilter/xt_DSCP.h
@@ -0,0 +1,21 @@
+/* x_tables module for setting the IPv4/IPv6 DSCP field
+ *
+ * (C) 2002 Harald Welte <laforge@gnumonks.org>
+ * based on ipt_FTOS.c (C) 2000 by Matthew G. Marsh <mgm@paktronix.com>
+ * This software is distributed under GNU GPL v2, 1991
+ *
+ * See RFC2474 for a description of the DSCP field within the IP Header.
+ *
+ * xt_DSCP.h,v 1.7 2002/03/14 12:03:13 laforge Exp
+*/
+#ifndef _XT_DSCP_TARGET_H
+#define _XT_DSCP_TARGET_H
+
+#include <linux/netfilter/xt_dscp.h>
+
+/* target info */
+struct xt_DSCP_info {
+	u_int8_t dscp;
+};
+
+#endif /* _XT_DSCP_TARGET_H */
diff --git a/include/linux/netfilter/xt_dscp.h b/include/linux/netfilter/xt_dscp.h
new file mode 100644
index 0000000..bf88360
--- /dev/null
+++ b/include/linux/netfilter/xt_dscp.h
@@ -0,0 +1,17 @@
+/* x_tables module for matching the IPv4/IPv6 DSCP field
+ *
+ * (C) 2002 Harald Welte <laforge@gnumonks.org>
+ * This software is distributed under GNU GPL v2, 1991
+ *
+ * See RFC2474 for a description of the DSCP field within the IP Header.
+ *
+ * xt_dscp.h,v 1.3 2002/08/05 19:00:21 laforge Exp
+*/
+#ifndef _XT_DSCP_H
+#define _XT_DSCP_H
+
+#define XT_DSCP_MASK	0xfc	/* 11111100 */
+#define XT_DSCP_SHIFT	2
+#define XT_DSCP_MAX	0x3f	/* 00111111 */
+
+#endif /* _XT_DSCP_H */
diff --git a/net/netfilter/Kconfig b/net/netfilter/Kconfig
index 71a532d..15116c7 100644
--- a/net/netfilter/Kconfig
+++ b/net/netfilter/Kconfig
@@ -206,6 +206,17 @@ config NETFILTER_XT_TARGET_CONNSECMARK
 
 	  To compile it as a module, choose M here.  If unsure, say N.
 
+config NETFILTER_XT_TARGET_DSCP
+	tristate '"DSCP" target support'
+	depends on IP_NF_MANGLE || IP6_NF_MANGLE
+	help
+	  This option adds a `DSCP' target, which allows you to manipulate
+	  the IPv4/IPv6 header DSCP field (differentiated services codepoint).
+
+	  The DSCP field can have any value between 0x0 and 0x3f inclusive.
+
+	  To compile it as a module, choose M here.  If unsure, say N.
+
 config NETFILTER_XT_MATCH_COMMENT
 	tristate  '"comment" match support'
 	depends on NETFILTER_XTABLES
diff --git a/net/netfilter/Makefile b/net/netfilter/Makefile
index 82054a4..7ff9b05 100644
--- a/net/netfilter/Makefile
+++ b/net/netfilter/Makefile
@@ -30,6 +30,7 @@ obj-$(CONFIG_NETFILTER_XT_TARGET_NFQUEUE) += xt_NFQUEUE.o
 obj-$(CONFIG_NETFILTER_XT_TARGET_NOTRACK) += xt_NOTRACK.o
 obj-$(CONFIG_NETFILTER_XT_TARGET_SECMARK) += xt_SECMARK.o
 obj-$(CONFIG_NETFILTER_XT_TARGET_CONNSECMARK) += xt_CONNSECMARK.o
+obj-$(CONFIG_NETFILTER_XT_TARGET_DSCP) += xt_DSCP.o
 
 # matches
 obj-$(CONFIG_NETFILTER_XT_MATCH_COMMENT) += xt_comment.o
diff --git a/net/netfilter/xt_DSCP.c b/net/netfilter/xt_DSCP.c
new file mode 100644
index 0000000..9410cc6
--- /dev/null
+++ b/net/netfilter/xt_DSCP.c
@@ -0,0 +1,123 @@
+/* x_tables module for setting the IPv4/IPv6 DSCP field, Version 1.8
+ *
+ * (C) 2002 by Harald Welte <laforge@netfilter.org>
+ * based on ipt_FTOS.c (C) 2000 by Matthew G. Marsh <mgm@paktronix.com>
+ *
+ * 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.
+ *
+ * See RFC2474 for a description of the DSCP field within the IP Header.
+*/
+
+#include <linux/module.h>
+#include <linux/skbuff.h>
+#include <linux/ip.h>
+#include <linux/ipv6.h>
+#include <net/dsfield.h>
+
+#include <linux/netfilter/x_tables.h>
+#include <linux/netfilter/xt_DSCP.h>
+
+MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
+MODULE_DESCRIPTION("Xtables: DSCP field modification");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("ipt_DSCP");
+MODULE_ALIAS("ip6t_DSCP");
+
+static unsigned int
+dscp_tg(struct sk_buff **pskb, const struct net_device *in,
+       const struct net_device *out, unsigned int hooknum,
+       const struct xt_target *target, const void *targinfo,
+       void *userinfo)
+{
+	const struct xt_DSCP_info *dinfo = targinfo;
+	u_int8_t dscp = ipv4_get_dsfield(ip_hdr(*pskb)) >> XT_DSCP_SHIFT;
+
+	if (dscp != dinfo->dscp) {
+		if (!skb_make_writable(pskb, sizeof(struct iphdr)))
+			return NF_DROP;
+
+		ipv4_change_dsfield(ip_hdr(*pskb), (__u8)(~XT_DSCP_MASK),
+				    dinfo->dscp << XT_DSCP_SHIFT);
+
+	}
+	return XT_CONTINUE;
+}
+
+static unsigned int
+dscp_tg6(struct sk_buff **pskb, const struct net_device *in,
+	 const struct net_device *out, unsigned int hooknum,
+	 const struct xt_target *target, const void *targinfo,
+	 void *userinfo)
+{
+	const struct xt_DSCP_info *dinfo = targinfo;
+	u_int8_t dscp = ipv6_get_dsfield(ipv6_hdr(*pskb)) >> XT_DSCP_SHIFT;
+
+	if (dscp != dinfo->dscp) {
+		if (!skb_make_writable(pskb, sizeof(struct ipv6hdr)))
+			return NF_DROP;
+
+		ipv6_change_dsfield(ipv6_hdr(*pskb), (__u8)(~XT_DSCP_MASK),
+				    dinfo->dscp << XT_DSCP_SHIFT);
+	}
+	return XT_CONTINUE;
+}
+
+static int dscp_tg_check(const char *tablename, const void *inf,
+			 const struct xt_target *target, void *targetinfo,
+			 unsigned int targetinfosize, unsigned int hook_mask)
+{
+	const struct xt_DSCP_info *info = targetinfo;
+
+	if (info->dscp > XT_DSCP_MAX) {
+		printk(KERN_WARNING "DSCP: dscp %x out of range\n", info->dscp);
+		return 0;
+	}
+
+	return 1;
+}
+
+static struct xt_target dscp_reg __read_mostly = {
+	.name		= "DSCP",
+	.family		= AF_INET,
+	.checkentry	= dscp_tg_check,
+	.target		= dscp_tg,
+	.targetsize	= sizeof(struct xt_DSCP_info),
+	.table		= "mangle",
+	.me		= THIS_MODULE,
+};
+
+static struct xt_target dscp6_reg __read_mostly = {
+	.name		= "DSCP",
+	.family		= AF_INET6,
+	.checkentry	= dscp_tg_check,
+	.target		= dscp_tg6,
+	.targetsize	= sizeof(struct xt_DSCP_info),
+	.table		= "mangle",
+	.me		= THIS_MODULE,
+};
+
+static int __init dscp_tg_init(void)
+{
+	int ret;
+
+	ret = xt_register_target(&dscp_reg);
+	if (ret)
+		return ret;
+
+	ret = xt_register_target(&dscp6_reg);
+	if (ret)
+		xt_unregister_target(&dscp_reg);
+
+	return ret;
+}
+
+static void __exit dscp_tg_exit(void)
+{
+	xt_unregister_target(&dscp6_reg);
+	xt_unregister_target(&dscp_reg);
+}
+
+module_init(dscp_tg_init);
+module_exit(dscp_tg_exit);