wifi: cfg80211: validate MLO connections better

When going into an MLO connection, validate that the link IDs
match what userspace indicated, and that the AP MLD addresses
and capabilities are all matching between the links.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Reviewed-by: Gregory Greenman <gregory.greenman@intel.com>
Signed-off-by: Miri Korenblit <miriam.rachel.korenblit@intel.com>
Link: https://msgid.link/20240102213313.ff83c034cb9a.I9962db0bfa8c73b37b8d5b59a3fad7f02f2129ae@changeid
[roll in extra fix from Miri to actually check the return value]
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

1 files changed, 24 insertions, 0 deletions

diff --git a/include/linux/ieee80211.h b/include/linux/ieee80211.h
index f0c068446c79..a70388ae3a7b 100644
--- a/include/linux/ieee80211.h
+++ b/include/linux/ieee80211.h
@@ -4936,6 +4936,30 @@ static inline u8 ieee80211_mle_common_size(const u8 *data)
 }
 
 /**
+ * ieee80211_mle_get_link_id - returns the link ID
+ * @data: the basic 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 BSS link ID can't be found, -1 will be returned
+ */
+static inline int ieee80211_mle_get_link_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_LINK_ID))
+		return -1;
+
+	return *common;
+}
+
+/**
  * ieee80211_mle_get_bss_param_ch_cnt - returns the BSS parameter change count
  * @mle: the basic multi link element
  *