mac80211: add support for .ndo_fill_forward_path

This allows drivers to provide a destination device + info for flow offload
Only supported in combination with 802.3 encap offload

Signed-off-by: Felix Fietkau <[e-mail]>
Tested-by: Lorenzo Bianconi <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Johannes Berg <[e-mail]>

include/net/mac80211.h

···
  *	radar channel.
  *	The caller is expected to set chandef pointer to NULL in order to
  *	disable offchannel CAC/radar detection.
+ * @net_fill_forward_path: Called from .ndo_fill_forward_path in order to
+ *	resolve a path for hardware flow offloading
  */
 struct ieee80211_ops {
 	void (*tx)(struct ieee80211_hw *hw,
···
 				     struct ieee80211_sta *sta, u8 flowid);
 	int (*set_radar_offchan)(struct ieee80211_hw *hw,
 				 struct cfg80211_chan_def *chandef);
+	int (*net_fill_forward_path)(struct ieee80211_hw *hw,
+				     struct ieee80211_vif *vif,
+				     struct ieee80211_sta *sta,
+				     struct net_device_path_ctx *ctx,
+				     struct net_device_path *path);
 };
 
 /**

net/mac80211/driver-ops.h

···
 	trace_drv_return_void(local);
 }
 
+static inline int drv_net_fill_forward_path(struct ieee80211_local *local,
+					    struct ieee80211_sub_if_data *sdata,
+					    struct ieee80211_sta *sta,
+					    struct net_device_path_ctx *ctx,
+					    struct net_device_path *path)
+{
+	int ret = -EOPNOTSUPP;
+
+	sdata = get_bss_sdata(sdata);
+	if (!check_sdata_in_driver(sdata))
+		return -EIO;
+
+	trace_drv_net_fill_forward_path(local, sdata, sta);
+	if (local->ops->net_fill_forward_path)
+		ret = local->ops->net_fill_forward_path(&local->hw,
+							&sdata->vif, sta,
+							ctx, path);
+	trace_drv_return_int(local, ret);
+
+	return ret;
+}
+
 #endif /* __MAC80211_DRIVER_OPS */

net/mac80211/ieee80211_i.h

···
 };
 
 static inline struct ieee80211_sub_if_data *
-IEEE80211_DEV_TO_SUB_IF(struct net_device *dev)
+IEEE80211_DEV_TO_SUB_IF(const struct net_device *dev)
 {
 	return netdev_priv(dev);
 }

net/mac80211/iface.c

···
 	.ndo_get_stats64	= ieee80211_get_stats64,
 };
 
+static int ieee80211_netdev_fill_forward_path(struct net_device_path_ctx *ctx,
+					      struct net_device_path *path)
+{
+	struct ieee80211_sub_if_data *sdata;
+	struct ieee80211_local *local;
+	struct sta_info *sta;
+	int ret = -ENOENT;
+
+	sdata = IEEE80211_DEV_TO_SUB_IF(ctx->dev);
+	local = sdata->local;
+
+	if (!local->ops->net_fill_forward_path)
+		return -EOPNOTSUPP;
+
+	rcu_read_lock();
+	switch (sdata->vif.type) {
+	case NL80211_IFTYPE_AP_VLAN:
+		sta = rcu_dereference(sdata->u.vlan.sta);
+		if (sta)
+			break;
+		if (sdata->wdev.use_4addr)
+			goto out;
+		if (is_multicast_ether_addr(ctx->daddr))
+			goto out;
+		sta = sta_info_get_bss(sdata, ctx->daddr);
+		break;
+	case NL80211_IFTYPE_AP:
+		if (is_multicast_ether_addr(ctx->daddr))
+			goto out;
+		sta = sta_info_get(sdata, ctx->daddr);
+		break;
+	case NL80211_IFTYPE_STATION:
+		if (sdata->wdev.wiphy->flags & WIPHY_FLAG_SUPPORTS_TDLS) {
+			sta = sta_info_get(sdata, ctx->daddr);
+			if (sta && test_sta_flag(sta, WLAN_STA_TDLS_PEER)) {
+				if (!test_sta_flag(sta, WLAN_STA_TDLS_PEER_AUTH))
+					goto out;
+
+				break;
+			}
+		}
+
+		sta = sta_info_get(sdata, sdata->u.mgd.bssid);
+		break;
+	default:
+		goto out;
+	}
+
+	if (!sta)
+		goto out;
+
+	ret = drv_net_fill_forward_path(local, sdata, &sta->sta, ctx, path);
+out:
+	rcu_read_unlock();
+
+	return ret;
+}
+
 static const struct net_device_ops ieee80211_dataif_8023_ops = {
 	.ndo_open		= ieee80211_open,
 	.ndo_stop		= ieee80211_stop,
···
 	.ndo_set_mac_address	= ieee80211_change_mac,
 	.ndo_select_queue	= ieee80211_netdev_select_queue,
 	.ndo_get_stats64	= ieee80211_get_stats64,
+	.ndo_fill_forward_path	= ieee80211_netdev_fill_forward_path,
 };
 
 static bool ieee80211_iftype_supports_hdr_offload(enum nl80211_iftype iftype)

net/mac80211/trace.h

···
 	)
 );
 
+DEFINE_EVENT(sta_event, drv_net_fill_forward_path,
+	TP_PROTO(struct ieee80211_local *local,
+		 struct ieee80211_sub_if_data *sdata,
+		 struct ieee80211_sta *sta),
+	TP_ARGS(local, sdata, sta)
+);
+
 #endif /* !__MAC80211_DRIVER_TRACE || TRACE_HEADER_MULTI_READ */
 
 #undef TRACE_INCLUDE_PATH