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>

1 files changed, 58 insertions, 1 deletions

diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c
index 0cda46a..f4cfd3a 100644
--- a/net/wireless/nl80211.c
+++ b/net/wireless/nl80211.c
@@ -190,6 +190,7 @@ static const struct nla_policy nl80211_policy[NL80211_ATTR_MAX+1] = {
 	[NL80211_ATTR_IE_ASSOC_RESP] = { .type = NLA_BINARY,
 					 .len = IEEE80211_MAX_DATA_LEN },
 	[NL80211_ATTR_ROAM_SUPPORT] = { .type = NLA_FLAG },
+	[NL80211_ATTR_SCHED_SCAN_MATCH] = { .type = NLA_NESTED },
 };
 
 /* policy for the key attributes */
@@ -232,6 +233,12 @@ nl80211_rekey_policy[NUM_NL80211_REKEY_DATA] = {
 	[NL80211_REKEY_DATA_REPLAY_CTR] = { .len = NL80211_REPLAY_CTR_LEN },
 };
 
+static const struct nla_policy
+nl80211_match_policy[NL80211_SCHED_SCAN_MATCH_ATTR_MAX + 1] = {
+	[NL80211_ATTR_SCHED_SCAN_MATCH_SSID] = { .type = NLA_BINARY,
+						 .len = IEEE80211_MAX_SSID_LEN },
+};
+
 /* ifidx get helper */
 static int nl80211_get_ifidx(struct netlink_callback *cb)
 {
@@ -715,6 +722,8 @@ static int nl80211_send_wiphy(struct sk_buff *msg, u32 pid, u32 seq, int flags,
 		    dev->wiphy.max_scan_ie_len);
 	NLA_PUT_U16(msg, NL80211_ATTR_MAX_SCHED_SCAN_IE_LEN,
 		    dev->wiphy.max_sched_scan_ie_len);
+	NLA_PUT_U8(msg, NL80211_ATTR_MAX_MATCH_SETS,
+		   dev->wiphy.max_match_sets);
 
 	if (dev->wiphy.flags & WIPHY_FLAG_IBSS_RSN)
 		NLA_PUT_FLAG(msg, NL80211_ATTR_SUPPORT_IBSS_RSN);
@@ -3632,10 +3641,11 @@ static int nl80211_start_sched_scan(struct sk_buff *skb,
 	struct net_device *dev = info->user_ptr[1];
 	struct nlattr *attr;
 	struct wiphy *wiphy;
-	int err, tmp, n_ssids = 0, n_channels, i;
+	int err, tmp, n_ssids = 0, n_match_sets = 0, n_channels, i;
 	u32 interval;
 	enum ieee80211_band band;
 	size_t ie_len;
+	struct nlattr *tb[NL80211_SCHED_SCAN_MATCH_ATTR_MAX + 1];
 
 	if (!(rdev->wiphy.flags & WIPHY_FLAG_SUPPORTS_SCHED_SCAN) ||
 	    !rdev->ops->sched_scan_start)
@@ -3674,6 +3684,15 @@ static int nl80211_start_sched_scan(struct sk_buff *skb,
 	if (n_ssids > wiphy->max_sched_scan_ssids)
 		return -EINVAL;
 
+	if (info->attrs[NL80211_ATTR_SCHED_SCAN_MATCH])
+		nla_for_each_nested(attr,
+				    info->attrs[NL80211_ATTR_SCHED_SCAN_MATCH],
+				    tmp)
+			n_match_sets++;
+
+	if (n_match_sets > wiphy->max_match_sets)
+		return -EINVAL;
+
 	if (info->attrs[NL80211_ATTR_IE])
 		ie_len = nla_len(info->attrs[NL80211_ATTR_IE]);
 	else
@@ -3691,6 +3710,7 @@ static int nl80211_start_sched_scan(struct sk_buff *skb,
 
 	request = kzalloc(sizeof(*request)
 			+ sizeof(*request->ssids) * n_ssids
+			+ sizeof(*request->match_sets) * n_match_sets
 			+ sizeof(*request->channels) * n_channels
 			+ ie_len, GFP_KERNEL);
 	if (!request) {
@@ -3708,6 +3728,18 @@ static int nl80211_start_sched_scan(struct sk_buff *skb,
 			request->ie = (void *)(request->channels + n_channels);
 	}
 
+	if (n_match_sets) {
+		if (request->ie)
+			request->match_sets = (void *)(request->ie + ie_len);
+		else if (request->ssids)
+			request->match_sets =
+				(void *)(request->ssids + n_ssids);
+		else
+			request->match_sets =
+				(void *)(request->channels + n_channels);
+	}
+	request->n_match_sets = n_match_sets;
+
 	i = 0;
 	if (info->attrs[NL80211_ATTR_SCAN_FREQUENCIES]) {
 		/* user specified, bail out if channel not found */
@@ -3772,6 +3804,31 @@ static int nl80211_start_sched_scan(struct sk_buff *skb,
 		}
 	}
 
+	i = 0;
+	if (info->attrs[NL80211_ATTR_SCHED_SCAN_MATCH]) {
+		nla_for_each_nested(attr,
+				    info->attrs[NL80211_ATTR_SCHED_SCAN_MATCH],
+				    tmp) {
+			struct nlattr *ssid;
+
+			nla_parse(tb, NL80211_SCHED_SCAN_MATCH_ATTR_MAX,
+				  nla_data(attr), nla_len(attr),
+				  nl80211_match_policy);
+			ssid = tb[NL80211_ATTR_SCHED_SCAN_MATCH_SSID];
+			if (ssid) {
+				if (nla_len(ssid) > IEEE80211_MAX_SSID_LEN) {
+					err = -EINVAL;
+					goto out_free;
+				}
+				memcpy(request->match_sets[i].ssid.ssid,
+				       nla_data(ssid), nla_len(ssid));
+				request->match_sets[i].ssid.ssid_len =
+					nla_len(ssid);
+			}
+			i++;
+		}
+	}
+
 	if (info->attrs[NL80211_ATTR_IE]) {
 		request->ie_len = nla_len(info->attrs[NL80211_ATTR_IE]);
 		memcpy((void *)request->ie,