cfg80211: Add TDLS event to allow drivers to request operations

The NL80211_CMD_TDLS_OPER command was previously used only for userspace
request for the kernel code to perform TDLS operations. However, there
are also cases where the driver may need to request operations from
userspace, e.g., when using security on the AP path. Add a new cfg80211
function for generating a TDLS operation event for drivers to request a
new link to be set up (NL80211_TDLS_SETUP) or an existing link to be
torn down (NL80211_TDLS_TEARDOWN). Drivers can optionally use these
events, e.g., based on noticing data traffic being sent to a peer
station that is seen with good signal strength.
Signed-off-by: Jouni Malinen <jouni@qca.qualcomm.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

include/net/cfg80211.h

@@ -3593,6 +3593,25 @@ bool cfg80211_can_beacon_sec_chan(struct wiphy *wiphy,
 void cfg80211_ch_switch_notify(struct net_device *dev, int freq,
 			       enum nl80211_channel_type type);
 
+/*
+ * cfg80211_tdls_oper_request - request userspace to perform TDLS operation
+ * @dev: the device on which the operation is requested
+ * @peer: the MAC address of the peer device
+ * @oper: the requested TDLS operation (NL80211_TDLS_SETUP or
+ *	NL80211_TDLS_TEARDOWN)
+ * @reason_code: the reason code for teardown request
+ * @gfp: allocation flags
+ *
+ * This function is used to request userspace to perform TDLS operation that
+ * requires knowledge of keys, i.e., link setup or teardown when the AP
+ * connection uses encryption. This is optional mechanism for the driver to use
+ * if it can automatically determine when a TDLS link could be useful (e.g.,
+ * based on traffic and signal strength for a peer).
+ */
+void cfg80211_tdls_oper_request(struct net_device *dev, const u8 *peer,
+				enum nl80211_tdls_operation oper,
+				u16 reason_code, gfp_t gfp);
+
 /*
  * cfg80211_calculate_bitrate - calculate actual bitrate (in 100Kbps units)
  * @rate: given rate_info to calculate bitrate from

include/uapi/linux/nl80211.h

@@ -526,6 +526,12 @@
  *	of PMKSA caching dandidates.
  *
  * @NL80211_CMD_TDLS_OPER: Perform a high-level TDLS command (e.g. link setup).
+ *	In addition, this can be used as an event to request userspace to take
+ *	actions on TDLS links (set up a new link or tear down an existing one).
+ *	In such events, %NL80211_ATTR_TDLS_OPERATION indicates the requested
+ *	operation, %NL80211_ATTR_MAC contains the peer MAC address, and
+ *	%NL80211_ATTR_REASON_CODE the reason code to be used (only with
+ *	%NL80211_TDLS_TEARDOWN).
  * @NL80211_CMD_TDLS_MGMT: Send a TDLS management frame.
  *
  * @NL80211_CMD_UNEXPECTED_FRAME: Used by an application controlling an AP

net/wireless/nl80211.c

@@ -9027,6 +9027,53 @@ void cfg80211_report_obss_beacon(struct wiphy *wiphy,
 }
 EXPORT_SYMBOL(cfg80211_report_obss_beacon);
 
+void cfg80211_tdls_oper_request(struct net_device *dev, const u8 *peer,
+				enum nl80211_tdls_operation oper,
+				u16 reason_code, gfp_t gfp)
+{
+	struct wireless_dev *wdev = dev->ieee80211_ptr;
+	struct cfg80211_registered_device *rdev = wiphy_to_dev(wdev->wiphy);
+	struct sk_buff *msg;
+	void *hdr;
+	int err;
+
+	trace_cfg80211_tdls_oper_request(wdev->wiphy, dev, peer, oper,
+					 reason_code);
+
+	msg = nlmsg_new(NLMSG_DEFAULT_SIZE, gfp);
+	if (!msg)
+		return;
+
+	hdr = nl80211hdr_put(msg, 0, 0, 0, NL80211_CMD_TDLS_OPER);
+	if (!hdr) {
+		nlmsg_free(msg);
+		return;
+	}
+
+	if (nla_put_u32(msg, NL80211_ATTR_WIPHY, rdev->wiphy_idx) ||
+	    nla_put_u32(msg, NL80211_ATTR_IFINDEX, dev->ifindex) ||
+	    nla_put_u8(msg, NL80211_ATTR_TDLS_OPERATION, oper) ||
+	    nla_put(msg, NL80211_ATTR_MAC, ETH_ALEN, peer) ||
+	    (reason_code > 0 &&
+	     nla_put_u16(msg, NL80211_ATTR_REASON_CODE, reason_code)))
+		goto nla_put_failure;
+
+	err = genlmsg_end(msg, hdr);
+	if (err < 0) {
+		nlmsg_free(msg);
+		return;
+	}
+
+	genlmsg_multicast_netns(wiphy_net(&rdev->wiphy), msg, 0,
+				nl80211_mlme_mcgrp.id, gfp);
+	return;
+
+ nla_put_failure:
+	genlmsg_cancel(msg, hdr);
+	nlmsg_free(msg);
+}
+EXPORT_SYMBOL(cfg80211_tdls_oper_request);
+
 static int nl80211_netlink_notify(struct notifier_block * nb,
 				  unsigned long state,
 				  void *_notify)

net/wireless/trace.h

@@ -2157,6 +2157,29 @@ TRACE_EVENT(cfg80211_report_obss_beacon,
 		  WIPHY_PR_ARG, __entry->freq, __entry->sig_dbm)
 );
 
+TRACE_EVENT(cfg80211_tdls_oper_request,
+	TP_PROTO(struct wiphy *wiphy, struct net_device *netdev, const u8 *peer,
+		 enum nl80211_tdls_operation oper, u16 reason_code),
+	TP_ARGS(wiphy, netdev, peer, oper, reason_code),
+	TP_STRUCT__entry(
+		WIPHY_ENTRY
+		NETDEV_ENTRY
+		MAC_ENTRY(peer)
+		__field(enum nl80211_tdls_operation, oper)
+		__field(u16, reason_code)
+	),
+	TP_fast_assign(
+		WIPHY_ASSIGN;
+		NETDEV_ASSIGN;
+		MAC_ASSIGN(peer, peer);
+		__entry->oper = oper;
+		__entry->reason_code = reason_code;
+	),
+	TP_printk(WIPHY_PR_FMT ", " NETDEV_PR_FMT ", peer: " MAC_PR_FMT ", oper: %d, reason_code %u",
+		  WIPHY_PR_ARG, NETDEV_PR_ARG, MAC_PR_ARG(peer), __entry->oper,
+		  __entry->reason_code)
+	);
+
 TRACE_EVENT(cfg80211_scan_done,
 	TP_PROTO(struct cfg80211_scan_request *request, bool aborted),
 	TP_ARGS(request, aborted),