mac80211: fix A-MSDU outer SA/DA

According to IEEE 802.11-2012 section 8.3.2 table 8-19, the outer SA/DA
of A-MSDU frames need to be changed depending on FromDS/ToDS values.
Signed-off-by: Michael Braun <michael-dev@fami-braun.de>
[use ether_addr_copy and add alignment annotations]
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

include/net/mac80211.h

@@ -1438,7 +1438,7 @@ enum ieee80211_vif_flags {
 struct ieee80211_vif {
 	enum nl80211_iftype type;
 	struct ieee80211_bss_conf bss_conf;
-	u8 addr[ETH_ALEN];
+	u8 addr[ETH_ALEN] __aligned(2);
 	bool p2p;
 	bool csa_active;
 	bool mu_mimo_owner;

net/mac80211/ieee80211_i.h

@@ -443,7 +443,7 @@ struct ieee80211_if_managed {
 	struct ieee80211_mgd_auth_data *auth_data;
 	struct ieee80211_mgd_assoc_data *assoc_data;
 
-	u8 bssid[ETH_ALEN];
+	u8 bssid[ETH_ALEN] __aligned(2);
 
 	u16 aid;
 

net/mac80211/tx.c

@@ -3064,6 +3064,7 @@ static bool ieee80211_amsdu_prepare_head(struct ieee80211_sub_if_data *sdata,
 	int subframe_len = skb->len - hdr_len;
 	void *data;
 	u8 *qc, *h_80211_src, *h_80211_dst;
+	const u8 *bssid;
 
 	if (info->flags & IEEE80211_TX_CTL_RATE_CTRL_PROBE)
 		return false;
@@ -3087,6 +3088,28 @@ static bool ieee80211_amsdu_prepare_head(struct ieee80211_sub_if_data *sdata,
 	ether_addr_copy(amsdu_hdr->h_source, h_80211_src);
 	ether_addr_copy(amsdu_hdr->h_dest, h_80211_dst);
 
+	/* according to IEEE 802.11-2012 8.3.2 table 8-19, the outer SA/DA
+	 * fields needs to be changed to BSSID for A-MSDU frames depending
+	 * on FromDS/ToDS values.
+	 */
+	switch (sdata->vif.type) {
+	case NL80211_IFTYPE_STATION:
+		bssid = sdata->u.mgd.bssid;
+		break;
+	case NL80211_IFTYPE_AP:
+	case NL80211_IFTYPE_AP_VLAN:
+		bssid = sdata->vif.addr;
+		break;
+	default:
+		bssid = NULL;
+	}
+
+	if (bssid && ieee80211_has_fromds(hdr->frame_control))
+		ether_addr_copy(h_80211_src, bssid);
+
+	if (bssid && ieee80211_has_tods(hdr->frame_control))
+		ether_addr_copy(h_80211_dst, bssid);
+
 	qc = ieee80211_get_qos_ctl(hdr);
 	*qc |= IEEE80211_QOS_CTL_A_MSDU_PRESENT;