wifi: mac80211: fix multi-BSSID element parsing

When parsing a frame containing a multi-BSSID element, we
need to know both the transmitted and non-transmitted BSSID
so we can parse it correctly.

Unfortunately, in quite a number of cases, we got this wrong
and were passing the wrong BSSID or useless information:
 * the mgmt->bssid from a frame is only the transmitted
   BSSID if the frame is a beacon
 * passing just one of the parameters as non-NULL isn't
   useful and ignored

In those case where we need to parse for a specific BSS we
always have a BSS structure pointer, representing the BSS
we need, whether transmitted or not. Thus, pass that pointer
to the parsing function instead of the two BSSIDs.

Also fix two bugs:
 * we need to re-parse all the elements for the other BSS
   when iterating the non-transmitted BSSes in scan
 * we need to parse for the correct BSS when setting up
   the channel data in client code

Fixes: 78ac51f81532 ("mac80211: support multi-bssid")
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

1 files changed, 8 insertions, 14 deletions

diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h
index a8211ced719e..dc38f57fcdc9 100644
--- a/net/mac80211/ieee80211_i.h
+++ b/net/mac80211/ieee80211_i.h
@@ -2147,10 +2147,9 @@ static inline void ieee80211_tx_skb(struct ieee80211_sub_if_data *sdata,
  * @filter: bitmap of element IDs to filter out while calculating
  *	the element CRC
  * @crc: CRC starting value
- * @transmitter_bssid: transmitter BSSID to parse the multi-BSSID
- *	element
- * @bss_bssid: BSSID of the BSS we want to obtain elements for
- *	when parsing the multi-BSSID element
+ * @bss: the BSS to parse this as, for multi-BSSID cases this can
+ *	represent a non-transmitting BSS in which case the data
+ *	for that non-transmitting BSS is returned
  */
 struct ieee80211_elems_parse_params {
 	const u8 *start;
@@ -2158,8 +2157,7 @@ struct ieee80211_elems_parse_params {
 	bool action;
 	u64 filter;
 	u32 crc;
-	const u8 *transmitter_bssid;
-	const u8 *bss_bssid;
+	struct cfg80211_bss *bss;
 };
 
 struct ieee802_11_elems *
@@ -2168,8 +2166,7 @@ ieee802_11_parse_elems_full(struct ieee80211_elems_parse_params *params);
 static inline struct ieee802_11_elems *
 ieee802_11_parse_elems_crc(const u8 *start, size_t len, bool action,
 			   u64 filter, u32 crc,
-			   const u8 *transmitter_bssid,
-			   const u8 *bss_bssid)
+			   struct cfg80211_bss *bss)
 {
 	struct ieee80211_elems_parse_params params = {
 		.start = start,
@@ -2177,8 +2174,7 @@ ieee802_11_parse_elems_crc(const u8 *start, size_t len, bool action,
 		.action = action,
 		.filter = filter,
 		.crc = crc,
-		.transmitter_bssid = transmitter_bssid,
-		.bss_bssid = bss_bssid,
+		.bss = bss,
 	};
 
 	return ieee802_11_parse_elems_full(&params);
@@ -2186,11 +2182,9 @@ ieee802_11_parse_elems_crc(const u8 *start, size_t len, bool action,
 
 static inline struct ieee802_11_elems *
 ieee802_11_parse_elems(const u8 *start, size_t len, bool action,
-		       const u8 *transmitter_bssid,
-		       const u8 *bss_bssid)
+		       struct cfg80211_bss *bss)
 {
-	return ieee802_11_parse_elems_crc(start, len, action, 0, 0,
-					  transmitter_bssid, bss_bssid);
+	return ieee802_11_parse_elems_crc(start, len, action, 0, 0, bss);
 }