cfg80211: allow advertising vendor-specific capabilities

There may be cases where vendor-specific elements need to be
used over the air. Rather than have driver or firmware add
them and possibly cause problems that way, add them to the
iftype-data band capabilities. This way we can advertise to
userspace first, and use them in mac80211 next.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Link: https://lore.kernel.org/r/iwlwifi.20210618133832.e8c4f0347276.Iee5964682b3e9ec51fc1cd57a7c62383eaf6ddd7@changeid
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

include/net/cfg80211.h

@@ -371,11 +371,18 @@ struct ieee80211_sta_he_cap {
  * @he_cap: holds the HE capabilities
  * @he_6ghz_capa: HE 6 GHz capabilities, must be filled in for a
  *	6 GHz band channel (and 0 may be valid value).
+ * @vendor_elems: vendor element(s) to advertise
+ * @vendor_elems.data: vendor element(s) data
+ * @vendor_elems.len: vendor element(s) length
  */
 struct ieee80211_sband_iftype_data {
 	u16 types_mask;
 	struct ieee80211_sta_he_cap he_cap;
 	struct ieee80211_he_6ghz_capa he_6ghz_capa;
+	struct {
+		const u8 *data;
+		unsigned int len;
+	} vendor_elems;
 };
 
 /**

include/uapi/linux/nl80211.h

@@ -3654,6 +3654,8 @@ enum nl80211_mpath_info {
  *     defined
  * @NL80211_BAND_IFTYPE_ATTR_HE_6GHZ_CAPA: HE 6GHz band capabilities (__le16),
  *	given for all 6 GHz band channels
+ * @NL80211_BAND_IFTYPE_ATTR_VENDOR_ELEMS: vendor element capabilities that are
+ *	advertised on this band/for this iftype (binary)
  * @__NL80211_BAND_IFTYPE_ATTR_AFTER_LAST: internal use
  */
 enum nl80211_band_iftype_attr {
@@ -3665,6 +3667,7 @@ enum nl80211_band_iftype_attr {
 	NL80211_BAND_IFTYPE_ATTR_HE_CAP_MCS_SET,
 	NL80211_BAND_IFTYPE_ATTR_HE_CAP_PPE,
 	NL80211_BAND_IFTYPE_ATTR_HE_6GHZ_CAPA,
+	NL80211_BAND_IFTYPE_ATTR_VENDOR_ELEMS,
 
 	/* keep last */
 	__NL80211_BAND_IFTYPE_ATTR_AFTER_LAST,

net/wireless/nl80211.c

@@ -1731,6 +1731,11 @@ nl80211_send_iftype_data(struct sk_buff *msg,
 		    &iftdata->he_6ghz_capa))
 		return -ENOBUFS;
 
+	if (iftdata->vendor_elems.data && iftdata->vendor_elems.len &&
+	    nla_put(msg, NL80211_BAND_IFTYPE_ATTR_VENDOR_ELEMS,
+		    iftdata->vendor_elems.len, iftdata->vendor_elems.data))
+		return -ENOBUFS;
+
 	return 0;
 }