cfg80211: add support to probe unexercised mesh link

Adding support to allow mesh HWMP to measure link metrics on unexercised
direct mesh path by sending some data frames to other mesh points which
are not currently selected as a primary traffic path but only 1 hop away.
The absence of the primary path to the chosen node makes it necessary to
apply some form of marking on a chosen packet stream so that the packets
can be properly steered to the selected node for testing, and not by the
regular mesh path lookup.

Tested-by: Pradeep Kumar Chitrapu <pradeepc@codeaurora.org>
Signed-off-by: Rajkumar Manoharan <rmanohar@codeaurora.org>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

Author: Rajkumar Manoharan

include/net/cfg80211.h

@@ -3501,6 +3501,9 @@ struct cfg80211_update_owe_info {
  * @update_owe_info: Provide updated OWE info to driver. Driver implementing SME
  *	but offloading OWE processing to the user space will get the updated
  *	DH IE through this interface.
+ *
+ * @probe_mesh_link: Probe direct Mesh peer's link quality by sending data frame
+ *	and overrule HWMP path selection algorithm.
  */
 struct cfg80211_ops {
 	int	(*suspend)(struct wiphy *wiphy, struct cfg80211_wowlan *wow);
@@ -3817,6 +3820,8 @@ struct cfg80211_ops {
 			      struct cfg80211_pmsr_request *request);
 	int	(*update_owe_info)(struct wiphy *wiphy, struct net_device *dev,
 				   struct cfg80211_update_owe_info *owe_info);
+	int	(*probe_mesh_link)(struct wiphy *wiphy, struct net_device *dev,
+				   const u8 *buf, size_t len);
 };
 
 /*

include/uapi/linux/nl80211.h

@@ -1070,6 +1070,21 @@
  *	OWE AKM by the host drivers that implement SME but rely
  *	on the user space for the cryptographic/DH IE processing in AP mode.
  *
+ * @NL80211_CMD_PROBE_MESH_LINK: The requirement for mesh link metric
+ *	refreshing, is that from one mesh point we be able to send some data
+ *	frames to other mesh points which are not currently selected as a
+ *	primary traffic path, but which are only 1 hop away. The absence of
+ *	the primary path to the chosen node makes it necessary to apply some
+ *	form of marking on a chosen packet stream so that the packets can be
+ *	properly steered to the selected node for testing, and not by the
+ *	regular mesh path lookup. Further, the packets must be of type data
+ *	so that the rate control (often embedded in firmware) is used for
+ *	rate selection.
+ *
+ *	Here attribute %NL80211_ATTR_MAC is used to specify connected mesh
+ *	peer MAC address and %NL80211_ATTR_FRAME is used to specify the frame
+ *	content. The frame is ethernet data.
+ *
  * @NL80211_CMD_MAX: highest used command number
  * @__NL80211_CMD_AFTER_LAST: internal use
  */
@@ -1292,6 +1307,8 @@ enum nl80211_commands {
 
 	NL80211_CMD_UPDATE_OWE_INFO,
 
+	NL80211_CMD_PROBE_MESH_LINK,
+
 	/* add new commands above here */
 
 	/* used to define NL80211_CMD_MAX below */

net/wireless/nl80211.c

@@ -13404,6 +13404,47 @@ static int nl80211_update_owe_info(struct sk_buff *skb, struct genl_info *info)
 	return rdev_update_owe_info(rdev, dev, &owe_info);
 }
 
+static int nl80211_probe_mesh_link(struct sk_buff *skb, struct genl_info *info)
+{
+	struct cfg80211_registered_device *rdev = info->user_ptr[0];
+	struct net_device *dev = info->user_ptr[1];
+	struct wireless_dev *wdev = dev->ieee80211_ptr;
+	struct station_info sinfo = {};
+	const u8 *buf;
+	size_t len;
+	u8 *dest;
+	int err;
+
+	if (!rdev->ops->probe_mesh_link || !rdev->ops->get_station)
+		return -EOPNOTSUPP;
+
+	if (!info->attrs[NL80211_ATTR_MAC] ||
+	    !info->attrs[NL80211_ATTR_FRAME]) {
+		GENL_SET_ERR_MSG(info, "Frame or MAC missing");
+		return -EINVAL;
+	}
+
+	if (wdev->iftype != NL80211_IFTYPE_MESH_POINT)
+		return -EOPNOTSUPP;
+
+	dest = nla_data(info->attrs[NL80211_ATTR_MAC]);
+	buf = nla_data(info->attrs[NL80211_ATTR_FRAME]);
+	len = nla_len(info->attrs[NL80211_ATTR_FRAME]);
+
+	if (len < sizeof(struct ethhdr))
+		return -EINVAL;
+
+	if (!ether_addr_equal(buf, dest) || is_multicast_ether_addr(buf) ||
+	    !ether_addr_equal(buf + ETH_ALEN, dev->dev_addr))
+		return -EINVAL;
+
+	err = rdev_get_station(rdev, dev, dest, &sinfo);
+	if (err)
+		return err;
+
+	return rdev_probe_mesh_link(rdev, dev, dest, buf, len);
+}
+
 #define NL80211_FLAG_NEED_WIPHY		0x01
 #define NL80211_FLAG_NEED_NETDEV	0x02
 #define NL80211_FLAG_NEED_RTNL		0x04
@@ -14241,6 +14282,13 @@ static const struct genl_ops nl80211_ops[] = {
 		.internal_flags = NL80211_FLAG_NEED_NETDEV_UP |
 				  NL80211_FLAG_NEED_RTNL,
 	},
+	{
+		.cmd = NL80211_CMD_PROBE_MESH_LINK,
+		.doit = nl80211_probe_mesh_link,
+		.flags = GENL_UNS_ADMIN_PERM,
+		.internal_flags = NL80211_FLAG_NEED_NETDEV_UP |
+				  NL80211_FLAG_NEED_RTNL,
+	},
 };
 
 static struct genl_family nl80211_fam __ro_after_init = {

net/wireless/rdev-ops.h

@@ -1286,4 +1286,17 @@ static inline int rdev_update_owe_info(struct cfg80211_registered_device *rdev,
 	return ret;
 }
 
+static inline int
+rdev_probe_mesh_link(struct cfg80211_registered_device *rdev,
+		     struct net_device *dev, const u8 *dest,
+		     const void *buf, size_t len)
+{
+	int ret;
+
+	trace_rdev_probe_mesh_link(&rdev->wiphy, dev, dest, buf, len);
+	ret = rdev->ops->probe_mesh_link(&rdev->wiphy, dev, buf, len);
+	trace_rdev_return_int(&rdev->wiphy, ret);
+	return ret;
+}
+
 #endif /* __CFG80211_RDEV_OPS */

net/wireless/trace.h

@@ -3421,6 +3421,24 @@ TRACE_EVENT(cfg80211_update_owe_info_event,
 		      WIPHY_PR_ARG, NETDEV_PR_ARG, MAC_PR_ARG(peer))
 );
 
+TRACE_EVENT(rdev_probe_mesh_link,
+	TP_PROTO(struct wiphy *wiphy, struct net_device *netdev,
+		 const u8 *dest, const u8 *buf, size_t len),
+	TP_ARGS(wiphy, netdev, dest, buf, len),
+	TP_STRUCT__entry(
+		WIPHY_ENTRY
+		NETDEV_ENTRY
+		MAC_ENTRY(dest)
+	),
+	TP_fast_assign(
+		WIPHY_ASSIGN;
+		NETDEV_ASSIGN;
+		MAC_ASSIGN(dest, dest);
+	),
+	TP_printk(WIPHY_PR_FMT ", " NETDEV_PR_FMT ", " MAC_PR_FMT,
+		  WIPHY_PR_ARG, NETDEV_PR_ARG, MAC_PR_ARG(dest))
+);
+
 #endif /* !__RDEV_OPS_TRACE || TRACE_HEADER_MULTI_READ */
 
 #undef TRACE_INCLUDE_PATH