3 files changed, 121 insertions, 0 deletions
diff --git a/net/mpls/Kconfig b/net/mpls/Kconfig
new file mode 100644
index 0000000..37421db
--- /dev/null
+++ b/net/mpls/Kconfig
@@ -0,0 +1,9 @@
+#
+# MPLS configuration
+#
+config NET_MPLS_GSO
+	tristate "MPLS: GSO support"
+	help
+	 This is helper module to allow segmentation of non-MPLS GSO packets
+	 that have had MPLS stack entries pushed onto them and thus
+	 become MPLS GSO packets.
diff --git a/net/mpls/Makefile b/net/mpls/Makefile
new file mode 100644
index 0000000..0a3c171
--- /dev/null
+++ b/net/mpls/Makefile
@@ -0,0 +1,4 @@
+#
+# Makefile for MPLS.
+#
+obj-y += mpls_gso.o
diff --git a/net/mpls/mpls_gso.c b/net/mpls/mpls_gso.c
new file mode 100644
index 0000000..1bec121
--- /dev/null
+++ b/net/mpls/mpls_gso.c
@@ -0,0 +1,108 @@
+/*
+ *	MPLS GSO Support
+ *
+ *	Authors: Simon Horman (horms@verge.net.au)
+ *
+ *	This program is free software; you can redistribute it and/or
+ *	modify it under the terms of the GNU General Public License
+ *	as published by the Free Software Foundation; either version
+ *	2 of the License, or (at your option) any later version.
+ *
+ *	Based on: GSO portions of net/ipv4/gre.c
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/err.h>
+#include <linux/module.h>
+#include <linux/netdev_features.h>
+#include <linux/netdevice.h>
+#include <linux/skbuff.h>
+
+static struct sk_buff *mpls_gso_segment(struct sk_buff *skb,
+				       netdev_features_t features)
+{
+	struct sk_buff *segs = ERR_PTR(-EINVAL);
+	netdev_features_t mpls_features;
+	__be16 mpls_protocol;
+
+	if (unlikely(skb_shinfo(skb)->gso_type &
+				~(SKB_GSO_TCPV4 |
+				  SKB_GSO_TCPV6 |
+				  SKB_GSO_UDP |
+				  SKB_GSO_DODGY |
+				  SKB_GSO_TCP_ECN |
+				  SKB_GSO_GRE |
+				  SKB_GSO_MPLS)))
+		goto out;
+
+	/* Setup inner SKB. */
+	mpls_protocol = skb->protocol;
+	skb->protocol = skb->inner_protocol;
+
+	/* Push back the mac header that skb_mac_gso_segment() has pulled.
+	 * It will be re-pulled by the call to skb_mac_gso_segment() below
+	 */
+	__skb_push(skb, skb->mac_len);
+
+	/* Segment inner packet. */
+	mpls_features = skb->dev->mpls_features & netif_skb_features(skb);
+	segs = skb_mac_gso_segment(skb, mpls_features);
+
+
+	/* Restore outer protocol. */
+	skb->protocol = mpls_protocol;
+
+	/* Re-pull the mac header that the call to skb_mac_gso_segment()
+	 * above pulled.  It will be re-pushed after returning
+	 * skb_mac_gso_segment(), an indirect caller of this function.
+	 */
+	__skb_push(skb, skb->data - skb_mac_header(skb));
+
+out:
+	return segs;
+}
+
+static int mpls_gso_send_check(struct sk_buff *skb)
+{
+	return 0;
+}
+
+static struct packet_offload mpls_mc_offload = {
+	.type = cpu_to_be16(ETH_P_MPLS_MC),
+	.callbacks = {
+		.gso_send_check =	mpls_gso_send_check,
+		.gso_segment    =	mpls_gso_segment,
+	},
+};
+
+static struct packet_offload mpls_uc_offload = {
+	.type = cpu_to_be16(ETH_P_MPLS_UC),
+	.callbacks = {
+		.gso_send_check =	mpls_gso_send_check,
+		.gso_segment    =	mpls_gso_segment,
+	},
+};
+
+static int __init mpls_gso_init(void)
+{
+	pr_info("MPLS GSO support\n");
+
+	dev_add_offload(&mpls_uc_offload);
+	dev_add_offload(&mpls_mc_offload);
+
+	return 0;
+}
+
+static void __exit mpls_gso_exit(void)
+{
+	dev_remove_offload(&mpls_uc_offload);
+	dev_remove_offload(&mpls_mc_offload);
+}
+
+module_init(mpls_gso_init);
+module_exit(mpls_gso_exit);
+
+MODULE_DESCRIPTION("MPLS GSO support");
+MODULE_AUTHOR("Simon Horman (horms@verge.net.au)");
+MODULE_LICENSE("GPL");