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>

diff --git a/include/linux/nl80211.h b/include/linux/nl80211.h
index 387e6e2..8aa7bad 100644 (file)
--- 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 01c6bde..09024ab 100644 (file)
--- 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;
 

diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c
index 0cda46a..f4cfd3a 100644 (file)
--- 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,