wifi: cfg80211: use ML element parsing helpers

Use the existing ML element parsing helpers and add a new
one for this (ieee80211_mle_get_mld_id).

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Miri Korenblit <miriam.rachel.korenblit@intel.com>
Link: https://msgid.link/20240216135047.4da47b1f035b.I437a5570ac456449facb0b147851ef24a1e473c2@changeid
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

2 files changed, 46 insertions, 33 deletions

diff --git a/include/linux/ieee80211.h b/include/linux/ieee80211.h
index 303c75459897..3385a2cc5b09 100644
--- a/include/linux/ieee80211.h
+++ b/include/linux/ieee80211.h
@@ -5116,6 +5116,44 @@ static inline u16 ieee80211_mle_get_mld_capa_op(const u8 *data)
 }
 
 /**
+ * ieee80211_mle_get_mld_id - returns the MLD ID
+ * @data: pointer to the multi link element
+ *
+ * The element is assumed to be of the correct type (BASIC) and big enough,
+ * this must be checked using ieee80211_mle_type_ok().
+ *
+ * If the MLD ID is not present, 0 will be returned.
+ */
+static inline u8 ieee80211_mle_get_mld_id(const u8 *data)
+{
+	const struct ieee80211_multi_link_elem *mle = (const void *)data;
+	u16 control = le16_to_cpu(mle->control);
+	const u8 *common = mle->variable;
+
+	/*
+	 * common points now at the beginning of
+	 * ieee80211_mle_basic_common_info
+	 */
+	common += sizeof(struct ieee80211_mle_basic_common_info);
+
+	if (!(control & IEEE80211_MLC_BASIC_PRES_MLD_ID))
+		return 0;
+
+	if (control & IEEE80211_MLC_BASIC_PRES_LINK_ID)
+		common += 1;
+	if (control & IEEE80211_MLC_BASIC_PRES_BSS_PARAM_CH_CNT)
+		common += 1;
+	if (control & IEEE80211_MLC_BASIC_PRES_MED_SYNC_DELAY)
+		common += 2;
+	if (control & IEEE80211_MLC_BASIC_PRES_EML_CAPA)
+		common += 2;
+	if (control & IEEE80211_MLC_BASIC_PRES_MLD_CAPA_OP)
+		common += 2;
+
+	return *common;
+}
+
+/**
  * ieee80211_mle_size_ok - validate multi-link element size
  * @data: pointer to the element data
  * @len: length of the containing element
diff --git a/net/wireless/scan.c b/net/wireless/scan.c
index e46dfc71c497..7cf36b8d3ae7 100644
--- a/net/wireless/scan.c
+++ b/net/wireless/scan.c
@@ -2833,17 +2833,16 @@ cfg80211_parse_ml_elem_sta_data(struct wiphy *wiphy,
 	struct cfg80211_bss *bss;
 	u8 mld_id, reporter_link_id, bss_change_count;
 	u16 seen_links = 0;
-	const u8 *pos;
 	u8 i;
 
-	if (!ieee80211_mle_size_ok(elem->data + 1, elem->datalen - 1))
+	if (!ieee80211_mle_type_ok(elem->data + 1,
+				   IEEE80211_ML_CONTROL_TYPE_BASIC,
+				   elem->datalen - 1))
 		return;
 
-	ml_elem = (void *)elem->data + 1;
+	ml_elem = (void *)(elem->data + 1);
 	control = le16_to_cpu(ml_elem->control);
-	if (u16_get_bits(control, IEEE80211_ML_CONTROL_TYPE) !=
-	    IEEE80211_ML_CONTROL_TYPE_BASIC)
-		return;
+	ml_common_len = ml_elem->variable[0];
 
 	/* Must be present when transmitted by an AP (in a probe response) */
 	if (!(control & IEEE80211_MLC_BASIC_PRES_BSS_PARAM_CH_CNT) ||
@@ -2851,24 +2850,8 @@ cfg80211_parse_ml_elem_sta_data(struct wiphy *wiphy,
 	    !(control & IEEE80211_MLC_BASIC_PRES_MLD_CAPA_OP))
 		return;
 
-	ml_common_len = ml_elem->variable[0];
-
-	/* length + MLD MAC address */
-	pos = ml_elem->variable + 1 + 6;
-
-	reporter_link_id = pos[0];
-	pos += 1;
-
-	bss_change_count = pos[0];
-	pos += 1;
-
-	if (u16_get_bits(control, IEEE80211_MLC_BASIC_PRES_MED_SYNC_DELAY))
-		pos += 2;
-	if (u16_get_bits(control, IEEE80211_MLC_BASIC_PRES_EML_CAPA))
-		pos += 2;
-
-	/* MLD capabilities and operations */
-	pos += 2;
+	reporter_link_id = ieee80211_mle_get_link_id(elem->data + 1);
+	bss_change_count = ieee80211_mle_get_bss_param_ch_cnt(elem->data + 1);
 
 	/*
 	 * The MLD ID of the reporting AP is always zero. It is set if the AP
@@ -2876,15 +2859,7 @@ cfg80211_parse_ml_elem_sta_data(struct wiphy *wiphy,
 	 * relating to a nontransmitted BSS (matching the Multi-BSSID Index,
 	 * Draft P802.11be_D3.2, 35.3.4.2)
 	 */
-	if (u16_get_bits(control, IEEE80211_MLC_BASIC_PRES_MLD_ID)) {
-		mld_id = *pos;
-		pos += 1;
-	} else {
-		mld_id = 0;
-	}
-
-	/* Extended MLD capabilities and operations */
-	pos += 2;
+	mld_id = ieee80211_mle_get_mld_id(elem->data + 1);
 
 	/* Fully defrag the ML element for sta information/profile iteration */
 	mle = cfg80211_defrag_mle(elem, tx_data->ie, tx_data->ielen, gfp);