From 0a85df004667c99efc31fab07386823eefce3be5 Mon Sep 17 00:00:00 2001
From: Hao Zheng <hzheng@nicira.com>
Date: Thu, 11 Nov 2010 13:47:57 +0000
Subject: [PATCH] vlan: Add function to retrieve EtherType from vlan packets.
Depending on how a packet is vlan tagged (i.e. hardware accelerated or
not), the encapsulated protocol is stored in different locations. This
provides a consistent method of accessing that protocol, which is needed
by drivers, security checks, etc.
Signed-off-by: Hao Zheng <hzheng@nicira.com>
Signed-off-by: Jesse Gross <jesse@nicira.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---
include/linux/if_vlan.h | 25 +++++++++++++++++++++++++
1 file changed, 25 insertions(+)
diff --git a/include/linux/if_vlan.h b/include/linux/if_vlan.h
index c2f3a72712ce..635e1faec412 100644
--- a/include/linux/if_vlan.h
+++ b/include/linux/if_vlan.h
@@ -339,6 +339,31 @@ static inline int vlan_get_tag(const struct sk_buff *skb, u16 *vlan_tci)
}
}
+/**
+ * vlan_get_protocol - get protocol EtherType.
+ * @skb: skbuff to query
+ *
+ * Returns the EtherType of the packet, regardless of whether it is
+ * vlan encapsulated (normal or hardware accelerated) or not.
+ */
+static inline __be16 vlan_get_protocol(const struct sk_buff *skb)
+{
+ __be16 protocol = 0;
+
+ if (vlan_tx_tag_present(skb) ||
+ skb->protocol != cpu_to_be16(ETH_P_8021Q))
+ protocol = skb->protocol;
+ else {
+ __be16 proto, *protop;
+ protop = skb_header_pointer(skb, offsetof(struct vlan_ethhdr,
+ h_vlan_encapsulated_proto),
+ sizeof(proto), &proto);
+ if (likely(protop))
+ protocol = *protop;
+ }
+
+ return protocol;
+}
#endif /* __KERNEL__ */
/* VLAN IOCTLs are found in sockios.h */
--
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