[NETFILTER]: x_tables: replace IPv4 DSCP target by address family independent version

This replaces IPv4 DSCP target by address family independent version.
This also
	- utilizes dsfield.h to get/mangle DS field in IPv4/IPv6 header
	- fixes Kconfig help text.

Signed-off-by: Yasuyuki Kozakai <yasuyuki.kozakai@toshiba.co.jp>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 143 insertions, 0 deletions

diff --git a/net/netfilter/Kconfig b/net/netfilter/Kconfig
index f781405f5d65..0a28d2c5c44f 100644
--- a/net/netfilter/Kconfig
+++ b/net/netfilter/Kconfig
@@ -148,6 +148,18 @@ config NETFILTER_XT_TARGET_CONNMARK
           <file:Documentation/modules.txt>.  The module will be called
           ipt_CONNMARK.o.  If unsure, say `N'.
 
+config NETFILTER_XT_TARGET_DSCP
+        tristate '"DSCP" target support'
+        depends on NETFILTER_XTABLES
+        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_TARGET_MARK
         tristate '"MARK" target support'
         depends on NETFILTER_XTABLES
diff --git a/net/netfilter/Makefile b/net/netfilter/Makefile
index 0b8a70c1df46..a74be492fd0a 100644
--- a/net/netfilter/Makefile
+++ b/net/netfilter/Makefile
@@ -25,6 +25,7 @@ obj-$(CONFIG_NETFILTER_XTABLES) += x_tables.o xt_tcpudp.o
 # targets
 obj-$(CONFIG_NETFILTER_XT_TARGET_CLASSIFY) += xt_CLASSIFY.o
 obj-$(CONFIG_NETFILTER_XT_TARGET_CONNMARK) += xt_CONNMARK.o
+obj-$(CONFIG_NETFILTER_XT_TARGET_DSCP) += xt_DSCP.o
 obj-$(CONFIG_NETFILTER_XT_TARGET_MARK) += xt_MARK.o
 obj-$(CONFIG_NETFILTER_XT_TARGET_NFQUEUE) += xt_NFQUEUE.o
 obj-$(CONFIG_NETFILTER_XT_TARGET_NOTRACK) += xt_NOTRACK.o
diff --git a/net/netfilter/xt_DSCP.c b/net/netfilter/xt_DSCP.c
new file mode 100644
index 000000000000..79df8165cd79
--- /dev/null
+++ b/net/netfilter/xt_DSCP.c
@@ -0,0 +1,130 @@
+/* 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.
+ *
+ * xt_DSCP.c,v 1.8 2002/08/06 18:41:57 laforge Exp
+*/
+
+#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("x_tables DSCP modification module");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("ipt_DSCP");
+MODULE_ALIAS("ip6t_DSCP");
+
+static unsigned int target(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((*pskb)->nh.iph) >> XT_DSCP_SHIFT;
+
+        if (dscp != dinfo->dscp) {
+                if (!skb_make_writable(pskb, sizeof(struct iphdr)))
+                        return NF_DROP;
+
+                ipv4_change_dsfield((*pskb)->nh.iph, (__u8)(~XT_DSCP_MASK),
+                                    dinfo->dscp << XT_DSCP_SHIFT);
+
+        }
+        return XT_CONTINUE;
+}
+
+static unsigned int target6(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((*pskb)->nh.ipv6h) >> XT_DSCP_SHIFT;
+
+        if (dscp != dinfo->dscp) {
+                if (!skb_make_writable(pskb, sizeof(struct ipv6hdr)))
+                        return NF_DROP;
+
+                ipv6_change_dsfield((*pskb)->nh.ipv6h, (__u8)(~XT_DSCP_MASK),
+                                    dinfo->dscp << XT_DSCP_SHIFT);
+        }
+        return XT_CONTINUE;
+}
+
+static int checkentry(const char *tablename,
+                      const void *e_void,
+                      const struct xt_target *target,
+                      void *targinfo,
+                      unsigned int targinfosize,
+                      unsigned int hook_mask)
+{
+        const u_int8_t dscp = ((struct xt_DSCP_info *)targinfo)->dscp;
+
+        if ((dscp > XT_DSCP_MAX)) {
+                printk(KERN_WARNING "DSCP: dscp %x out of range\n", dscp);
+                return 0;
+        }
+        return 1;
+}
+
+static struct xt_target xt_dscp_reg = {
+        .name           = "DSCP",
+        .target         = target,
+        .targetsize     = sizeof(struct xt_DSCP_info),
+        .table          = "mangle",
+        .checkentry     = checkentry,
+        .family         = AF_INET,
+        .me             = THIS_MODULE,
+};
+
+static struct xt_target xt_dscp6_reg = {
+        .name           = "DSCP",
+        .target         = target6,
+        .targetsize     = sizeof(struct xt_DSCP_info),
+        .table          = "mangle",
+        .checkentry     = checkentry,
+        .family         = AF_INET6,
+        .me             = THIS_MODULE,
+};
+
+static int __init xt_dscp_target_init(void)
+{
+        int ret;
+        ret = xt_register_target(&xt_dscp_reg);
+        if (ret)
+                return ret;
+
+        ret = xt_register_target(&xt_dscp6_reg);
+        if (ret)
+                xt_unregister_target(&xt_dscp_reg);
+
+        return ret;
+}
+
+static void __exit xt_dscp_target_fini(void)
+{
+        xt_unregister_target(&xt_dscp_reg);
+        xt_unregister_target(&xt_dscp6_reg);
+}
+
+module_init(xt_dscp_target_init);
+module_exit(xt_dscp_target_fini);