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 515a35e2a48ab7e55d550fcd164466080773b3ce..960e666c51e44620686b6aad9fdbfbc3d325b95e 100644 (file)
--- a/include/linux/if_vlan.h
+++ b/include/linux/if_vlan.h
@@ -472,27 +472,59 @@ static inline int vlan_get_tag(const struct sk_buff *skb, u16 *vlan_tci)
 /**
  * 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;
-
-       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;
+       unsigned int vlan_depth = skb->mac_len;
+
+       /* 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,

diff --git a/net/core/dev.c b/net/core/dev.c
index 171420e75b03e5b9a020e6d417b72efbed5d5aba..c87a2264a02bf55473d4def744a63d3c4230455f 100644 (file)
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -2352,7 +2352,6 @@ EXPORT_SYMBOL(skb_checksum_help);
 
 __be16 skb_network_protocol(struct sk_buff *skb, int *depth)
 {
-       unsigned int vlan_depth = skb->mac_len;
        __be16 type = skb->protocol;
 
        /* Tunnel gso handlers can set protocol to ethernet. */
@@ -2366,35 +2365,7 @@ __be16 skb_network_protocol(struct sk_buff *skb, int *depth)
                type = eth->h_proto;
        }
 
-       /* if skb->protocol 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));
-       }
-
-       *depth = vlan_depth;
-
-       return type;
+       return __vlan_get_protocol(skb, type, depth);
 }
 
 /**