mac80211: fix encryption key selection for 802.3 xmit

When using WEP, the default unicast key needs to be selected, instead of
the STA PTK.
Signed-off-by: Felix Fietkau <nbd@nbd.name>
Link: https://lore.kernel.org/r/20201218184718.93650-4-nbd@nbd.nameSigned-off-by: Johannes Berg <johannes.berg@intel.com>

net/mac80211/tx.c

@@ -4251,7 +4251,6 @@ netdev_tx_t ieee80211_subif_start_xmit_8023(struct sk_buff *skb,
 	struct ethhdr *ehdr = (struct ethhdr *)skb->data;
 	struct ieee80211_key *key;
 	struct sta_info *sta;
-	bool offload = true;
 
 	if (unlikely(skb->len < ETH_HLEN)) {
 		kfree_skb(skb);
@@ -4267,18 +4266,22 @@ netdev_tx_t ieee80211_subif_start_xmit_8023(struct sk_buff *skb,
 
 	if (unlikely(IS_ERR_OR_NULL(sta) || !sta->uploaded ||
 	    !test_sta_flag(sta, WLAN_STA_AUTHORIZED) ||
-		sdata->control_port_protocol == ehdr->h_proto))
-		offload = false;
-	else if ((key = rcu_dereference(sta->ptk[sta->ptk_idx])) &&
-		 (!(key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE) ||
-		  key->conf.cipher == WLAN_CIPHER_SUITE_TKIP))
-		offload = false;
-
-	if (offload)
-		ieee80211_8023_xmit(sdata, dev, sta, key, skb);
-	else
-		ieee80211_subif_start_xmit(skb, dev);
+	    sdata->control_port_protocol == ehdr->h_proto))
+		goto skip_offload;
+
+	key = rcu_dereference(sta->ptk[sta->ptk_idx]);
+	if (!key)
+		key = rcu_dereference(sdata->default_unicast_key);
+
+	if (key && (!(key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE) ||
+		    key->conf.cipher == WLAN_CIPHER_SUITE_TKIP))
+		goto skip_offload;
+
+	ieee80211_8023_xmit(sdata, dev, sta, key, skb);
+	goto out;
 
+skip_offload:
+	ieee80211_subif_start_xmit(skb, dev);
 out:
 	rcu_read_unlock();