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>

2 files changed, 19 insertions, 15 deletions

diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c
index 807d448..93bc63e 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 02a2383..b7a1679 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);