wifi: cfg80211: factor out bridge tunnel / RFC1042 header check

The same check is done in multiple places, unify it.

Signed-off-by: Felix Fietkau <nbd@nbd.name>
Link: https://lore.kernel.org/r/20230213100855.34315-2-nbd@nbd.name
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

diff --git a/net/wireless/util.c b/net/wireless/util.c
index 430962f..4498807 100644 (file)
--- a/net/wireless/util.c
+++ b/net/wireless/util.c
@@ -542,6 +542,21 @@ unsigned int ieee80211_get_mesh_hdrlen(struct ieee80211s_hdr *meshhdr)
 }
 EXPORT_SYMBOL(ieee80211_get_mesh_hdrlen);
 
+static bool ieee80211_get_8023_tunnel_proto(const void *hdr, __be16 *proto)
+{
+       const __be16 *hdr_proto = hdr + ETH_ALEN;
+
+       if (!(ether_addr_equal(hdr, rfc1042_header) &&
+             *hdr_proto != htons(ETH_P_AARP) &&
+             *hdr_proto != htons(ETH_P_IPX)) &&
+           !ether_addr_equal(hdr, bridge_tunnel_header))
+               return false;
+
+       *proto = *hdr_proto;
+
+       return true;
+}
+
 int ieee80211_data_to_8023_exthdr(struct sk_buff *skb, struct ethhdr *ehdr,
                                  const u8 *addr, enum nl80211_iftype iftype,
                                  u8 data_offset, bool is_amsdu)
@@ -633,14 +648,9 @@ int ieee80211_data_to_8023_exthdr(struct sk_buff *skb, struct ethhdr *ehdr,
 
        if (likely(!is_amsdu &&
                   skb_copy_bits(skb, hdrlen, &payload, sizeof(payload)) == 0 &&
-                  ((ether_addr_equal(payload.hdr, rfc1042_header) &&
-                    payload.proto != htons(ETH_P_AARP) &&
-                    payload.proto != htons(ETH_P_IPX)) ||
-                   ether_addr_equal(payload.hdr, bridge_tunnel_header)))) {
-               /* remove RFC1042 or Bridge-Tunnel encapsulation and
-                * replace EtherType */
+                  ieee80211_get_8023_tunnel_proto(&payload, &tmp.h_proto))) {
+               /* remove RFC1042 or Bridge-Tunnel encapsulation */
                hdrlen += ETH_ALEN + 2;
-               tmp.h_proto = payload.proto;
                skb_postpull_rcsum(skb, &payload, ETH_ALEN + 2);
        } else {
                tmp.h_proto = htons(skb->len - hdrlen);
@@ -756,8 +766,6 @@ void ieee80211_amsdu_to_8023s(struct sk_buff *skb, struct sk_buff_head *list,
 {
        unsigned int hlen = ALIGN(extra_headroom, 4);
        struct sk_buff *frame = NULL;
-       u16 ethertype;
-       u8 *payload;
        int offset = 0, remaining;
        struct ethhdr eth;
        bool reuse_frag = skb->head_frag && !skb_has_frag_list(skb);
@@ -811,14 +819,8 @@ void ieee80211_amsdu_to_8023s(struct sk_buff *skb, struct sk_buff_head *list,
                frame->dev = skb->dev;
                frame->priority = skb->priority;
 
-               payload = frame->data;
-               ethertype = (payload[6] << 8) | payload[7];
-               if (likely((ether_addr_equal(payload, rfc1042_header) &&
-                           ethertype != ETH_P_AARP && ethertype != ETH_P_IPX) ||
-                          ether_addr_equal(payload, bridge_tunnel_header))) {
-                       eth.h_proto = htons(ethertype);
+               if (likely(ieee80211_get_8023_tunnel_proto(frame->data, &eth.h_proto)))
                        skb_pull(frame, ETH_ALEN + 2);
-               }
 
                memcpy(skb_push(frame, sizeof(eth)), &eth, sizeof(eth));
                __skb_queue_tail(list, frame);