nl80211/cfg80211: add match filtering for sched_scan

Introduce filtering for scheduled scans to reduce the number of
unnecessary results (which cause useless wake-ups).

Add a new nested attribute where sets of parameters to be matched can
be passed when starting a scheduled scan.  Only scan results that
match any of the sets will be returned.

At this point, the set consists of a single parameter, an SSID.  This
can be easily extended in the future to support more complex matches.

Signed-off-by: Luciano Coelho <coelho@ti.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

2 files changed, 63 insertions, 0 deletions

diff --git a/include/linux/nl80211.h b/include/linux/nl80211.h
index 387e6e22050..8aa7badc196 100644
--- a/include/linux/nl80211.h
+++ b/include/linux/nl80211.h
@@ -769,6 +769,8 @@ enum nl80211_commands {
  *	that can be added to a scan request
  * @NL80211_ATTR_MAX_SCHED_SCAN_IE_LEN: maximum length of information
  *	elements that can be added to a scheduled scan request
+ * @NL80211_ATTR_MAX_MATCH_SETS: maximum number of sets that can be
+ *	used with @NL80211_ATTR_SCHED_SCAN_MATCH, a wiphy attribute.
  *
  * @NL80211_ATTR_SCAN_FREQUENCIES: nested attribute with frequencies (in MHz)
  * @NL80211_ATTR_SCAN_SSIDS: nested attribute with SSIDs, leave out for passive
@@ -1011,6 +1013,24 @@ enum nl80211_commands {
 
  * @NL80211_ATTR_SCHED_SCAN_INTERVAL: Interval between scheduled scan
  *	cycles, in msecs.
+
+ * @NL80211_ATTR_SCHED_SCAN_MATCH: Nested attribute with one or more
+ *	sets of attributes to match during scheduled scans.  Only BSSs
+ *	that match any of the sets will be reported.  These are
+ *	pass-thru filter rules.
+ *	For a match to succeed, the BSS must match all attributes of a
+ *	set.  Since not every hardware supports matching all types of
+ *	attributes, there is no guarantee that the reported BSSs are
+ *	fully complying with the match sets and userspace needs to be
+ *	able to ignore them by itself.
+ *	Thus, the implementation is somewhat hardware-dependent, but
+ *	this is only an optimization and the userspace application
+ *	needs to handle all the non-filtered results anyway.
+ *	If the match attributes don't make sense when combined with
+ *	the values passed in @NL80211_ATTR_SCAN_SSIDS (eg. if an SSID
+ *	is included in the probe request, but the match attributes
+ *	will never let it go through), -EINVAL may be returned.
+ *	If ommited, no filtering is done.
  *
  * @NL80211_ATTR_INTERFACE_COMBINATIONS: Nested attribute listing the supported
  *	interface combinations. In each nested item, it contains attributes
@@ -1265,6 +1285,9 @@ enum nl80211_attrs {
 
 	NL80211_ATTR_ROAM_SUPPORT,
 
+	NL80211_ATTR_SCHED_SCAN_MATCH,
+	NL80211_ATTR_MAX_MATCH_SETS,
+
 	/* add attributes here, update the policy in nl80211.c */
 
 	__NL80211_ATTR_AFTER_LAST,
@@ -1724,6 +1747,26 @@ enum nl80211_reg_rule_attr {
 };
 
 /**
+ * enum nl80211_sched_scan_match_attr - scheduled scan match attributes
+ * @__NL80211_SCHED_SCAN_MATCH_ATTR_INVALID: attribute number 0 is reserved
+ * @NL80211_SCHED_SCAN_MATCH_ATTR_SSID: SSID to be used for matching,
+ * only report BSS with matching SSID.
+ * @NL80211_SCHED_SCAN_MATCH_ATTR_MAX: highest scheduled scan filter
+ *	attribute number currently defined
+ * @__NL80211_SCHED_SCAN_MATCH_ATTR_AFTER_LAST: internal use
+ */
+enum nl80211_sched_scan_match_attr {
+	__NL80211_SCHED_SCAN_MATCH_ATTR_INVALID,
+
+	NL80211_ATTR_SCHED_SCAN_MATCH_SSID,
+
+	/* keep last */
+	__NL80211_SCHED_SCAN_MATCH_ATTR_AFTER_LAST,
+	NL80211_SCHED_SCAN_MATCH_ATTR_MAX =
+		__NL80211_SCHED_SCAN_MATCH_ATTR_AFTER_LAST - 1
+};
+
+/**
  * enum nl80211_reg_rule_flags - regulatory rule flags
  *
  * @NL80211_RRF_NO_OFDM: OFDM modulation not allowed
diff --git a/include/net/cfg80211.h b/include/net/cfg80211.h
index 01c6bde99a4..09024ab617f 100644
--- a/include/net/cfg80211.h
+++ b/include/net/cfg80211.h
@@ -876,6 +876,15 @@ struct cfg80211_scan_request {
 };
 
 /**
+ * struct cfg80211_match_set - sets of attributes to match
+ *
+ * @ssid: SSID to be matched
+ */
+struct cfg80211_match_set {
+	struct cfg80211_ssid ssid;
+};
+
+/**
  * struct cfg80211_sched_scan_request - scheduled scan request description
  *
  * @ssids: SSIDs to scan for (passed in the probe_reqs in active scans)
@@ -884,6 +893,11 @@ struct cfg80211_scan_request {
  * @interval: interval between each scheduled scan cycle
  * @ie: optional information element(s) to add into Probe Request or %NULL
  * @ie_len: length of ie in octets
+ * @match_sets: sets of parameters to be matched for a scan result
+ * 	entry to be considered valid and to be passed to the host
+ * 	(others are filtered out).
+ *	If ommited, all results are passed.
+ * @n_match_sets: number of match sets
  * @wiphy: the wiphy this was for
  * @dev: the interface
  * @channels: channels to scan
@@ -895,6 +909,8 @@ struct cfg80211_sched_scan_request {
 	u32 interval;
 	const u8 *ie;
 	size_t ie_len;
+	struct cfg80211_match_set *match_sets;
+	int n_match_sets;
 
 	/* internal */
 	struct wiphy *wiphy;
@@ -1814,6 +1830,9 @@ struct wiphy_wowlan_support {
  *	any given scan
  * @max_sched_scan_ssids: maximum number of SSIDs the device can scan
  *	for in any given scheduled scan
+ * @max_match_sets: maximum number of match sets the device can handle
+ *	when performing a scheduled scan, 0 if filtering is not
+ *	supported.
  * @max_scan_ie_len: maximum length of user-controlled IEs device can
  *	add to probe request frames transmitted during a scan, must not
  *	include fixed IEs like supported rates
@@ -1871,6 +1890,7 @@ struct wiphy {
 	int bss_priv_size;
 	u8 max_scan_ssids;
 	u8 max_sched_scan_ssids;
+	u8 max_match_sets;
 	u16 max_scan_ie_len;
 	u16 max_sched_scan_ie_len;