net: Fix vlan_get_protocol for stacked vlan
vlan_get_protocol() could not get network protocol if a skb has a 802.1ad
vlan tag or multiple vlans, which caused incorrect checksum calculation
in several drivers.
Fix vlan_get_protocol() to retrieve network protocol instead of incorrect
vlan protocol.
As the logic is the same as skb_network_protocol(), create a common helper
function __vlan_get_protocol() and call it from existing functions.
Signed-off-by: Toshiaki Makita <makita.toshiaki@lab.ntt.co.jp>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/linux/if_vlan.h b/include/linux/if_vlan.h
index 515a35e2..960e666 100644
--- a/include/linux/if_vlan.h
+++ b/include/linux/if_vlan.h
@@ -472,27 +472,59 @@
/**
* vlan_get_protocol - get protocol EtherType.
* @skb: skbuff to query
+ * @type: first vlan protocol
+ * @depth: buffer to store length of eth and vlan tags in bytes
*
* 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)
+static inline __be16 __vlan_get_protocol(struct sk_buff *skb, __be16 type,
+ int *depth)
{
- __be16 protocol = 0;
+ unsigned int vlan_depth = skb->mac_len;
- 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;
+ /* if type is 802.1Q/AD then the header should already be
+ * present at mac_len - VLAN_HLEN (if mac_len > 0), or at
+ * ETH_HLEN otherwise
+ */
+ if (type == htons(ETH_P_8021Q) || type == htons(ETH_P_8021AD)) {
+ if (vlan_depth) {
+ if (WARN_ON(vlan_depth < VLAN_HLEN))
+ return 0;
+ vlan_depth -= VLAN_HLEN;
+ } else {
+ vlan_depth = ETH_HLEN;
+ }
+ do {
+ struct vlan_hdr *vh;
+
+ if (unlikely(!pskb_may_pull(skb,
+ vlan_depth + VLAN_HLEN)))
+ return 0;
+
+ vh = (struct vlan_hdr *)(skb->data + vlan_depth);
+ type = vh->h_vlan_encapsulated_proto;
+ vlan_depth += VLAN_HLEN;
+ } while (type == htons(ETH_P_8021Q) ||
+ type == htons(ETH_P_8021AD));
}
- return protocol;
+ if (depth)
+ *depth = vlan_depth;
+
+ return type;
+}
+
+/**
+ * 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(struct sk_buff *skb)
+{
+ return __vlan_get_protocol(skb, skb->protocol, NULL);
}
static inline void vlan_set_encap_proto(struct sk_buff *skb,