From 0a85df004667c99efc31fab07386823eefce3be5 Mon Sep 17 00:00:00 2001 From: Hao Zheng 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 Signed-off-by: Jesse Gross Signed-off-by: David S. Miller --- 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 */