[PATCH] wifi: cfg80211: copy multi-link element from the multi-link probe request's frame body to the generated elements

[Michael-CY Lee]

According to Draft P802.11be_D7.0 clause 35.3.4.2, if a multi-link
request requests an MLD with which an AP corresponding to the
nontransmitted BSSID, the corresponding multi-link probe response
shall carry a basic multi-mink element of that MLD in the frame body
of the multi-link probe response, whose location is outside of the
Multiple BSSID element carried in the frame.

Therefore additional handing is needed for parsing multi-link probe
response and generating the merged elements so that the MLD in the frame
body can be correctly copied to the generated elements. Otherwise, the
nontransmitted BSS looks like non-MLD.

Signed-off-by: Money Wang <money.wang at mediatek.com>
Signed-off-by: Michael-CY Lee <michael-cy.lee at mediatek.com>
---
 net/wireless/scan.c | 27 ++++++++++++++++++++++++++-
 1 file changed, 26 insertions(+), 1 deletion(-)

diff --git a/net/wireless/scan.c b/net/wireless/scan.c
index 8e3d46bf4836..b244378e0bad 100644
--- a/net/wireless/scan.c
+++ b/net/wireless/scan.c
@@ -272,12 +272,19 @@ cfg80211_gen_new_ie(const u8 *ie, size_t ielen,
 {
 	const struct element *non_inherit_elem, *parent, *sub;
 	u8 *pos = new_ie;
-	u8 id, ext_id;
+	const u8 *mbssid_index_ie;
+	u8 id, ext_id, bssid_index = 255;
 	unsigned int match_len;
 
 	non_inherit_elem = cfg80211_find_ext_elem(WLAN_EID_EXT_NON_INHERITANCE,
 						  subie, subie_len);
 
+	mbssid_index_ie = cfg80211_find_ie(WLAN_EID_MULTI_BSSID_IDX, subie,
+					   subie_len);
+	if (mbssid_index_ie && mbssid_index_ie[1] > 0 &&
+	    mbssid_index_ie[2] > 0 && mbssid_index_ie[2] <= 46)
+		bssid_index = mbssid_index_ie[2];
+
 	/* We copy the elements one by one from the parent to the generated
 	 * elements.
 	 * If they are not inherited (included in subie or in the non
@@ -316,6 +323,24 @@ cfg80211_gen_new_ie(const u8 *ie, size_t ielen,
 			continue;
 		}
 
+		/* For ML probe response, match the MLE in the frame body with
+		 * MLD id being 'bssid_index'
+		 */
+		if (parent->id == WLAN_EID_EXTENSION && parent->datalen > 1 &&
+		    parent->data[0] == WLAN_EID_EXT_EHT_MULTI_LINK &&
+		    bssid_index == ieee80211_mle_get_mld_id(parent->data + 1)) {
+			if (!cfg80211_copy_elem_with_frags(parent,
+							   ie, ielen,
+							   &pos, new_ie,
+							   new_ie_len))
+				return 0;
+
+			/* Continue here to prevent processing the MLE in
+			 * sub-element, which AP MLD should not carry
+			 */
+			continue;
+		}
+
 		/* Already copied if an earlier element had the same type */
 		if (cfg80211_find_elem_match(id, ie, (u8 *)parent - ie,
 					     &ext_id, match_len, 0))
-- 
2.25.1