[NETFILTER]: IPv6 capable xt_TOS v1 target

Extends the xt_DSCP target by xt_TOS v1 to add support for selectively
setting and flipping any bit in the IPv4 TOS and IPv6 Priority fields.
(ipt_TOS and xt_DSCP only accepted a limited range of possible
values.)

Signed-off-by: Jan Engelhardt <jengelh@computergmbh.de>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 69 insertions, 1 deletions

diff --git a/include/linux/netfilter/xt_DSCP.h b/include/linux/netfilter/xt_DSCP.h
index 3c7c963997bd..14da1968e2c6 100644
--- a/include/linux/netfilter/xt_DSCP.h
+++ b/include/linux/netfilter/xt_DSCP.h
@@ -17,4 +17,9 @@ struct xt_DSCP_info {
         u_int8_t dscp;
 };
 
+struct xt_tos_target_info {
+        u_int8_t tos_value;
+        u_int8_t tos_mask;
+};
+
 #endif /* _XT_DSCP_TARGET_H */
diff --git a/net/netfilter/Kconfig b/net/netfilter/Kconfig
index 9c82d4cc86bf..7bde6315999a 100644
--- a/net/netfilter/Kconfig
+++ b/net/netfilter/Kconfig
@@ -304,7 +304,7 @@ config NETFILTER_XT_TARGET_DSCP
 
           It also adds the "TOS" target, which allows you to create rules in
           the "mangle" table which alter the Type Of Service field of an IPv4
-          packet prior to routing.
+          or the Priority field of an IPv6 packet, prior to routing.
 
           To compile it as a module, choose M here.  If unsure, say N.
 
diff --git a/net/netfilter/xt_DSCP.c b/net/netfilter/xt_DSCP.c
index 40a4f1d71916..fd7500ecadfd 100644
--- a/net/netfilter/xt_DSCP.c
+++ b/net/netfilter/xt_DSCP.c
@@ -26,6 +26,7 @@ MODULE_LICENSE("GPL");
 MODULE_ALIAS("ipt_DSCP");
 MODULE_ALIAS("ip6t_DSCP");
 MODULE_ALIAS("ipt_TOS");
+MODULE_ALIAS("ip6t_TOS");
 
 static unsigned int
 dscp_tg(struct sk_buff *skb, const struct net_device *in,
@@ -117,6 +118,50 @@ tos_tg_check_v0(const char *tablename, const void *e_void,
         return true;
 }
 
+static unsigned int
+tos_tg(struct sk_buff *skb, const struct net_device *in,
+       const struct net_device *out, unsigned int hooknum,
+       const struct xt_target *target, const void *targinfo)
+{
+        const struct xt_tos_target_info *info = targinfo;
+        struct iphdr *iph = ip_hdr(skb);
+        u_int8_t orig, nv;
+
+        orig = ipv4_get_dsfield(iph);
+        nv   = (orig & info->tos_mask) ^ info->tos_value;
+
+        if (orig != nv) {
+                if (!skb_make_writable(skb, sizeof(struct iphdr)))
+                        return NF_DROP;
+                iph = ip_hdr(skb);
+                ipv4_change_dsfield(iph, ~0, nv);
+        }
+
+        return XT_CONTINUE;
+}
+
+static unsigned int
+tos_tg6(struct sk_buff *skb, const struct net_device *in,
+        const struct net_device *out, unsigned int hooknum,
+        const struct xt_target *target, const void *targinfo)
+{
+        const struct xt_tos_target_info *info = targinfo;
+        struct ipv6hdr *iph = ipv6_hdr(skb);
+        u_int8_t orig, nv;
+
+        orig = ipv6_get_dsfield(iph);
+        nv   = (orig & info->tos_mask) ^ info->tos_value;
+
+        if (orig != nv) {
+                if (!skb_make_writable(skb, sizeof(struct iphdr)))
+                        return NF_DROP;
+                iph = ipv6_hdr(skb);
+                ipv6_change_dsfield(iph, ~0, nv);
+        }
+
+        return XT_CONTINUE;
+}
+
 static struct xt_target dscp_tg_reg[] __read_mostly = {
         {
                 .name           = "DSCP",
@@ -146,6 +191,24 @@ static struct xt_target dscp_tg_reg[] __read_mostly = {
                 .checkentry     = tos_tg_check_v0,
                 .me             = THIS_MODULE,
         },
+        {
+                .name           = "TOS",
+                .revision       = 1,
+                .family         = AF_INET,
+                .table          = "mangle",
+                .target         = tos_tg,
+                .targetsize     = sizeof(struct xt_tos_target_info),
+                .me             = THIS_MODULE,
+        },
+        {
+                .name           = "TOS",
+                .revision       = 1,
+                .family         = AF_INET6,
+                .table          = "mangle",
+                .target         = tos_tg6,
+                .targetsize     = sizeof(struct xt_tos_target_info),
+                .me             = THIS_MODULE,
+        },
 };
 
 static int __init dscp_tg_init(void)