cfg80211: move TSF into IEs

While technically the TSF isn't an IE, it can be
necessary to distinguish between the TSF from a
beacon and a probe response, in particular in
order to know the next DTIM TBTT, as not all APs
are spec compliant wrt. TSF==0 being a DTIM TBTT
and thus the DTIM count needs to be taken into
account as well.

To allow this, move the TSF into the IE struct
so it can be known whence it came.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>

4 files changed, 34 insertions, 20 deletions

diff --git a/net/mac80211/ibss.c b/net/mac80211/ibss.c
index 71c55cc0f7b6..055fa9436e95 100644
--- a/net/mac80211/ibss.c
+++ b/net/mac80211/ibss.c
@@ -242,6 +242,8 @@ static void ieee80211_sta_join_ibss(struct ieee80211_sub_if_data *sdata,
 	u32 basic_rates;
 	int i, j;
 	u16 beacon_int = cbss->beacon_interval;
+	const struct cfg80211_bss_ies *ies;
+	u64 tsf;
 
 	lockdep_assert_held(&sdata->u.ibss.mtx);
 
@@ -265,13 +267,17 @@ static void ieee80211_sta_join_ibss(struct ieee80211_sub_if_data *sdata,
 		}
 	}
 
+	rcu_read_lock();
+	ies = rcu_dereference(cbss->ies);
+	tsf = ies->tsf;
+	rcu_read_unlock();
+
 	__ieee80211_sta_join_ibss(sdata, cbss->bssid,
 				  beacon_int,
 				  cbss->channel,
 				  basic_rates,
 				  cbss->capability,
-				  cbss->tsf,
-				  false);
+				  tsf, false);
 }
 
 static struct sta_info *ieee80211_ibss_finish_sta(struct sta_info *sta,
@@ -535,8 +541,8 @@ static void ieee80211_rx_bss_info(struct ieee80211_sub_if_data *sdata,
 
 	cbss = container_of((void *)bss, struct cfg80211_bss, priv);
 
-	/* was just updated in ieee80211_bss_info_update */
-	beacon_timestamp = cbss->tsf;
+	/* same for beacon and probe response */
+	beacon_timestamp = le64_to_cpu(mgmt->u.beacon.timestamp);
 
 	/* check if we need to merge IBSS */
 
diff --git a/net/mac80211/mlme.c b/net/mac80211/mlme.c
index 40ce00c6d4ca..51eca5a0cdaa 100644
--- a/net/mac80211/mlme.c
+++ b/net/mac80211/mlme.c
@@ -3667,6 +3667,7 @@ static int ieee80211_prep_connection(struct ieee80211_sub_if_data *sdata,
 		bool have_higher_than_11mbit;
 		int min_rate = INT_MAX, min_rate_index = -1;
 		struct ieee80211_supported_band *sband;
+		const struct cfg80211_bss_ies *ies;
 
 		sband = local->hw.wiphy->bands[cbss->channel->band];
 
@@ -3710,7 +3711,10 @@ static int ieee80211_prep_connection(struct ieee80211_sub_if_data *sdata,
 
 		/* set timing information */
 		sdata->vif.bss_conf.beacon_int = cbss->beacon_interval;
-		sdata->vif.bss_conf.sync_tsf = cbss->tsf;
+		rcu_read_lock();
+		ies = rcu_dereference(cbss->ies);
+		sdata->vif.bss_conf.sync_tsf = ies->tsf;
+		rcu_read_unlock();
 		sdata->vif.bss_conf.sync_device_ts = bss->device_ts;
 
 		/* tell driver about BSSID, basic rates and timing */
diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c
index 807d448e702e..93bc63eae076 100644
--- a/net/wireless/nl80211.c
+++ b/net/wireless/nl80211.c
@@ -4997,6 +4997,7 @@ static int nl80211_send_bss(struct sk_buff *msg, struct netlink_callback *cb,
 	const struct cfg80211_bss_ies *ies;
 	void *hdr;
 	struct nlattr *bss;
+	bool tsf = false;
 
 	ASSERT_WDEV_LOCK(wdev);
 
@@ -5020,22 +5021,24 @@ static int nl80211_send_bss(struct sk_buff *msg, struct netlink_callback *cb,
 
 	rcu_read_lock();
 	ies = rcu_dereference(res->ies);
-	if (ies && ies->len && nla_put(msg, NL80211_BSS_INFORMATION_ELEMENTS,
-				       ies->len, ies->data)) {
-		rcu_read_unlock();
-		goto nla_put_failure;
+	if (ies) {
+		if (nla_put_u64(msg, NL80211_BSS_TSF, ies->tsf))
+			goto fail_unlock_rcu;
+		tsf = true;
+		if (ies->len && nla_put(msg, NL80211_BSS_INFORMATION_ELEMENTS,
+					ies->len, ies->data))
+			goto fail_unlock_rcu;
 	}
 	ies = rcu_dereference(res->beacon_ies);
-	if (ies && ies->len && nla_put(msg, NL80211_BSS_BEACON_IES,
-				       ies->len, ies->data)) {
-		rcu_read_unlock();
-		goto nla_put_failure;
+	if (ies) {
+		if (!tsf && nla_put_u64(msg, NL80211_BSS_TSF, ies->tsf))
+			goto fail_unlock_rcu;
+		if (ies->len && nla_put(msg, NL80211_BSS_BEACON_IES,
+					ies->len, ies->data))
+			goto fail_unlock_rcu;
 	}
 	rcu_read_unlock();
 
-	if (res->tsf &&
-	    nla_put_u64(msg, NL80211_BSS_TSF, res->tsf))
-		goto nla_put_failure;
 	if (res->beacon_interval &&
 	    nla_put_u16(msg, NL80211_BSS_BEACON_INTERVAL, res->beacon_interval))
 		goto nla_put_failure;
@@ -5080,6 +5083,8 @@ static int nl80211_send_bss(struct sk_buff *msg, struct netlink_callback *cb,
 
 	return genlmsg_end(msg, hdr);
 
+ fail_unlock_rcu:
+	rcu_read_unlock();
  nla_put_failure:
 	genlmsg_cancel(msg, hdr);
 	return -EMSGSIZE;
diff --git a/net/wireless/scan.c b/net/wireless/scan.c
index 02a238329c83..b7a167984986 100644
--- a/net/wireless/scan.c
+++ b/net/wireless/scan.c
@@ -695,7 +695,6 @@ cfg80211_bss_update(struct cfg80211_registered_device *dev,
 
 	if (found) {
 		found->pub.beacon_interval = tmp->pub.beacon_interval;
-		found->pub.tsf = tmp->pub.tsf;
 		found->pub.signal = tmp->pub.signal;
 		found->pub.capability = tmp->pub.capability;
 		found->ts = tmp->ts;
@@ -880,7 +879,6 @@ cfg80211_inform_bss(struct wiphy *wiphy,
 	memcpy(tmp.pub.bssid, bssid, ETH_ALEN);
 	tmp.pub.channel = channel;
 	tmp.pub.signal = signal;
-	tmp.pub.tsf = tsf;
 	tmp.pub.beacon_interval = beacon_interval;
 	tmp.pub.capability = capability;
 	/*
@@ -895,6 +893,7 @@ cfg80211_inform_bss(struct wiphy *wiphy,
 	if (!ies)
 		return NULL;
 	ies->len = ielen;
+	ies->tsf = tsf;
 	memcpy(ies->data, ie, ielen);
 
 	rcu_assign_pointer(tmp.pub.beacon_ies, ies);
@@ -951,6 +950,7 @@ cfg80211_inform_bss_frame(struct wiphy *wiphy,
 	if (!ies)
 		return NULL;
 	ies->len = ielen;
+	ies->tsf = le64_to_cpu(mgmt->u.probe_resp.timestamp);
 	memcpy(ies->data, mgmt->u.probe_resp.variable, ielen);
 
 	if (ieee80211_is_probe_resp(mgmt->frame_control))
@@ -962,7 +962,6 @@ cfg80211_inform_bss_frame(struct wiphy *wiphy,
 	memcpy(tmp.pub.bssid, mgmt->bssid, ETH_ALEN);
 	tmp.pub.channel = channel;
 	tmp.pub.signal = signal;
-	tmp.pub.tsf = le64_to_cpu(mgmt->u.probe_resp.timestamp);
 	tmp.pub.beacon_interval = le16_to_cpu(mgmt->u.probe_resp.beacon_int);
 	tmp.pub.capability = le16_to_cpu(mgmt->u.probe_resp.capab_info);
 
@@ -1409,7 +1408,7 @@ ieee80211_bss(struct wiphy *wiphy, struct iw_request_info *info,
 	if (buf) {
 		memset(&iwe, 0, sizeof(iwe));
 		iwe.cmd = IWEVCUSTOM;
-		sprintf(buf, "tsf=%016llx", (unsigned long long)(bss->pub.tsf));
+		sprintf(buf, "tsf=%016llx", (unsigned long long)(ies->tsf));
 		iwe.u.data.length = strlen(buf);
 		current_ev = iwe_stream_add_point(info, current_ev, end_buf,
 						  &iwe, buf);