netdev - [PATCH 3/3] net: GSO encapsulation for IP packets

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Message-ID: <alpine.DEB.2.02.1402110928030.7010@tomh.mtv.corp.google.com>
Date:	Tue, 11 Feb 2014 09:43:56 -0800 (PST)
From:	Tom Herbert <therbert@...gle.com>
To:	davem@...emloft.net, netdev@...r.kernel.org
cc:	ogerlitz@...lanox.com
Subject: [PATCH 3/3] net: GSO encapsulation for IP packets

The UDP GSO code assume that only encapsulated packets are Ethernet
frames. This patch fixes that so that we can support IP protocol
encpasulation (GUE, GRE/UDP, etc.)

We overload the inner_protocol field in the skb to store either the
Ethertype or the IP protocol (latter is indicated by ip_encapsulation
bit). As far as I can tell this should not adversely affect preexiting
uses for inner_protocol.

Signed-off-by: Tom Herbert <therbert@...gle.com>
---
 include/linux/skbuff.h |  8 ++++++--
 net/core/skbuff.c      |  1 +
 net/ipv4/udp.c         | 12 +++++++++++-
 3 files changed, 18 insertions(+), 3 deletions(-)

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 1f689e6..757ed39 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -512,7 +512,11 @@ struct sk_buff {
 	 * headers if needed
 	 */
 	__u8			encapsulation:1;
-	/* 6/8 bit hole (depending on ndisc_nodetype presence) */
+	/* skbuf encpasulates an IP packet, inner_protocol should be
+	 * interpreted as an IP protocol, encapsulation bit is also set
+	 */
+	__u8			ip_encapsulation:1;
+	/* 5/7 bit hole (depending on ndisc_nodetype presence) */
 	kmemcheck_bitfield_end(flags2);
 
 #if defined CONFIG_NET_DMA || defined CONFIG_NET_RX_BUSY_POLL
@@ -530,7 +534,7 @@ struct sk_buff {
 		__u32		reserved_tailroom;
 	};
 
-	__be16			inner_protocol;
+	__u16			inner_protocol;
 	__u16			inner_transport_header;
 	__u16			inner_network_header;
 	__u16			inner_mac_header;
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 8f519db..64c6190 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -687,6 +687,7 @@ static void __copy_skb_header(struct sk_buff *new, const struct sk_buff *old)
 	new->ooo_okay		= old->ooo_okay;
 	new->no_fcs		= old->no_fcs;
 	new->encapsulation	= old->encapsulation;
+	new->ip_encapsulation	= old->ip_encapsulation;
 #ifdef CONFIG_XFRM
 	new->sp			= secpath_get(old->sp);
 #endif
diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index 77bd16f..48d8cb2 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -2497,7 +2497,17 @@ struct sk_buff *skb_udp_tunnel_segment(struct sk_buff *skb,
 
 	/* segment inner packet. */
 	enc_features = skb->dev->hw_enc_features & netif_skb_features(skb);
-	segs = skb_mac_gso_segment(skb, enc_features);
+
+	if (skb->ip_encapsulation) {
+		const struct net_offload *ops;
+		ops = rcu_dereference(inet_offloads[skb->inner_protocol]);
+		if (likely(ops && ops->callbacks.gso_segment))
+			segs = ops->callbacks.gso_segment(skb, enc_features);
+	} else {
+		skb->protocol = htons(ETH_P_TEB);
+		segs = skb_mac_gso_segment(skb, enc_features);
+	}
+
 	if (!segs || IS_ERR(segs)) {
 		skb_gso_error_unwind(skb, protocol, tnl_hlen, mac_offset,
 				     mac_len);
-- 
1.9.0.rc1.175.g0b1dcb5

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