cfg80211: support profile split between elements

Since an element is limited to 255 octets, a profile may be split
split to several elements. Support the split as defined in the 11ax
draft 3. Detect legacy split and print a net-rate limited warning,
since there is no ROI in supporting this probably non-existent
split.

Signed-off-by: Sara Sharon <sara.sharon@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

include/net/cfg80211.h

@@ -5542,6 +5542,20 @@ static inline void cfg80211_gen_new_bssid(const u8 *bssid, u8 max_bssid,
 bool cfg80211_is_element_inherited(const struct element *element,
 				   const struct element *non_inherit_element);
 
+/**
+ * cfg80211_merge_profile - merges a MBSSID profile if it is split between IEs
+ * @ie: ies
+ * @ielen: length of IEs
+ * @mbssid_elem: current MBSSID element
+ * @sub_elem: current MBSSID subelement (profile)
+ * @merged_ie: location of the merged profile
+ * @max_copy_len: max merged profile length
+ */
+size_t cfg80211_merge_profile(const u8 *ie, size_t ielen,
+			      const struct element *mbssid_elem,
+			      const struct element *sub_elem,
+			      u8 **merged_ie, size_t max_copy_len);
+
 /**
  * enum cfg80211_bss_frame_type - frame type that the BSS data came from
  * @CFG80211_BSS_FTYPE_UNKNOWN: driver doesn't know whether the data is

net/wireless/scan.c

@@ -1456,6 +1456,78 @@ cfg80211_inform_single_bss_data(struct wiphy *wiphy,
 	return &res->pub;
 }
 
+static const struct element
+*cfg80211_get_profile_continuation(const u8 *ie, size_t ielen,
+				   const struct element *mbssid_elem,
+				   const struct element *sub_elem)
+{
+	const u8 *mbssid_end = mbssid_elem->data + mbssid_elem->datalen;
+	const struct element *next_mbssid;
+	const struct element *next_sub;
+
+	next_mbssid = cfg80211_find_elem(WLAN_EID_MULTIPLE_BSSID,
+					 mbssid_end,
+					 ielen - (mbssid_end - ie));
+
+	/*
+	 * If is is not the last subelement in current MBSSID IE or there isn't
+	 * a next MBSSID IE - profile is complete.
+	*/
+	if ((sub_elem->data + sub_elem->datalen < mbssid_end - 1) ||
+	    !next_mbssid)
+		return NULL;
+
+	/* For any length error, just return NULL */
+
+	if (next_mbssid->datalen < 4)
+		return NULL;
+
+	next_sub = (void *)&next_mbssid->data[1];
+
+	if (next_mbssid->data + next_mbssid->datalen <
+	    next_sub->data + next_sub->datalen)
+		return NULL;
+
+	if (next_sub->id != 0 || next_sub->datalen < 2)
+		return NULL;
+
+	/*
+	 * Check if the first element in the next sub element is a start
+	 * of a new profile
+	 */
+	return next_sub->data[0] == WLAN_EID_NON_TX_BSSID_CAP ?
+	       NULL : next_mbssid;
+}
+
+size_t cfg80211_merge_profile(const u8 *ie, size_t ielen,
+			      const struct element *mbssid_elem,
+			      const struct element *sub_elem,
+			      u8 **merged_ie, size_t max_copy_len)
+{
+	size_t copied_len = sub_elem->datalen;
+	const struct element *next_mbssid;
+
+	if (sub_elem->datalen > max_copy_len)
+		return 0;
+
+	memcpy(*merged_ie, sub_elem->data, sub_elem->datalen);
+
+	while ((next_mbssid = cfg80211_get_profile_continuation(ie, ielen,
+								mbssid_elem,
+								sub_elem))) {
+		const struct element *next_sub = (void *)&next_mbssid->data[1];
+
+		if (copied_len + next_sub->datalen > max_copy_len)
+			break;
+		memcpy(*merged_ie + copied_len, next_sub->data,
+		       next_sub->datalen);
+		copied_len += next_sub->datalen;
+	}
+
+	return copied_len;
+}
+EXPORT_SYMBOL(cfg80211_merge_profile);
+
 static void cfg80211_parse_mbssid_data(struct wiphy *wiphy,
 				       struct cfg80211_inform_bss *data,
 				       enum cfg80211_bss_frame_type ftype,
@@ -1469,7 +1541,8 @@ static void cfg80211_parse_mbssid_data(struct wiphy *wiphy,
 	const struct element *elem, *sub;
 	size_t new_ie_len;
 	u8 new_bssid[ETH_ALEN];
-	u8 *new_ie;
+	u8 *new_ie, *profile;
+	u64 seen_indices = 0;
 	u16 capability;
 	struct cfg80211_bss *bss;
 
@@ -1487,10 +1560,16 @@ static void cfg80211_parse_mbssid_data(struct wiphy *wiphy,
 	if (!new_ie)
 		return;
 
+	profile = kmalloc(ielen, gfp);
+	if (!profile)
+		goto out;
+
 	for_each_element_id(elem, WLAN_EID_MULTIPLE_BSSID, ie, ielen) {
 		if (elem->datalen < 4)
 			continue;
 		for_each_element(sub, elem->data + 1, elem->datalen - 1) {
+			u8 profile_len;
+
 			if (sub->id != 0 || sub->datalen < 4) {
 				/* not a valid BSS profile */
 				continue;
@@ -1505,16 +1584,31 @@ static void cfg80211_parse_mbssid_data(struct wiphy *wiphy,
 				continue;
 			}
 
+			memset(profile, 0, ielen);
+			profile_len = cfg80211_merge_profile(ie, ielen,
+							     elem,
+							     sub,
+							     &profile,
+							     ielen);
+
 			/* found a Nontransmitted BSSID Profile */
 			mbssid_index_ie = cfg80211_find_ie
 				(WLAN_EID_MULTI_BSSID_IDX,
-				 sub->data, sub->datalen);
+				 profile, profile_len);
 			if (!mbssid_index_ie || mbssid_index_ie[1] < 1 ||
-			    mbssid_index_ie[2] == 0) {
+			    mbssid_index_ie[2] == 0 ||
+			    mbssid_index_ie[2] > 46) {
 				/* No valid Multiple BSSID-Index element */
 				continue;
 			}
 
+			if (seen_indices & BIT(mbssid_index_ie[2]))
+				/* We don't support legacy split of a profile */
+				net_dbg_ratelimited("Partial info for BSSID index %d\n",
+						    mbssid_index_ie[2]);
+
+			seen_indices |= BIT(mbssid_index_ie[2]);
+
 			non_tx_data->bssid_index = mbssid_index_ie[2];
 			non_tx_data->max_bssid_indicator = elem->data[0];
 
@@ -1523,13 +1617,14 @@ static void cfg80211_parse_mbssid_data(struct wiphy *wiphy,
 					       non_tx_data->bssid_index,
 					       new_bssid);
 			memset(new_ie, 0, IEEE80211_MAX_DATA_LEN);
-			new_ie_len = cfg80211_gen_new_ie(ie, ielen, sub->data,
-							 sub->datalen, new_ie,
+			new_ie_len = cfg80211_gen_new_ie(ie, ielen,
+							 profile,
+							 profile_len, new_ie,
 							 gfp);
 			if (!new_ie_len)
 				continue;
 
-			capability = get_unaligned_le16(sub->data + 2);
+			capability = get_unaligned_le16(profile + 2);
 			bss = cfg80211_inform_single_bss_data(wiphy, data,
 							      ftype,
 							      new_bssid, tsf,
@@ -1545,7 +1640,9 @@ static void cfg80211_parse_mbssid_data(struct wiphy *wiphy,
 		}
 	}
 
+out:
 	kfree(new_ie);
+	kfree(profile);
 }
 
 struct cfg80211_bss *