nl80211: correct checks for NL80211_MESHCONF_HT_OPMODE value

Previously, NL80211_MESHCONF_HT_OPMODE validation rejected correct
flag combinations, e.g. IEEE80211_HT_OP_MODE_PROTECTION_NONHT_MIXED |
IEEE80211_HT_OP_MODE_NON_HT_STA_PRSNT.

Doing just a range-check allows setting flags that don't exist (0x8)
and invalid flag combinations.

Implements some checks based on IEEE 802.11 2012 8.4.2.59 "HT
Operation element".
Signed-off-by: Masashi Honma <masashi.honma@gmail.com>
[reword commit message, simplify a bit]
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

net/wireless/nl80211.c

@@ -5380,6 +5380,7 @@ static int nl80211_parse_mesh_config(struct genl_info *info,
 {
 	struct nlattr *tb[NL80211_MESHCONF_ATTR_MAX + 1];
 	u32 mask = 0;
+	u16 ht_opmode;
 
 #define FILL_IN_MESH_PARAM_IF_SET(tb, cfg, param, min, max, mask, attr, fn) \
 do {									    \
@@ -5471,9 +5472,36 @@ do {									    \
 	FILL_IN_MESH_PARAM_IF_SET(tb, cfg, rssi_threshold, -255, 0,
 				  mask, NL80211_MESHCONF_RSSI_THRESHOLD,
 				  nl80211_check_s32);
-	FILL_IN_MESH_PARAM_IF_SET(tb, cfg, ht_opmode, 0, 16,
-				  mask, NL80211_MESHCONF_HT_OPMODE,
-				  nl80211_check_u16);
+	/*
+	 * Check HT operation mode based on
+	 * IEEE 802.11 2012 8.4.2.59 HT Operation element.
+	 */
+	if (tb[NL80211_MESHCONF_HT_OPMODE]) {
+		ht_opmode = nla_get_u16(tb[NL80211_MESHCONF_HT_OPMODE]);
+
+		if (ht_opmode & ~(IEEE80211_HT_OP_MODE_PROTECTION |
+				  IEEE80211_HT_OP_MODE_NON_GF_STA_PRSNT |
+				  IEEE80211_HT_OP_MODE_NON_HT_STA_PRSNT))
+			return -EINVAL;
+
+		if ((ht_opmode & IEEE80211_HT_OP_MODE_NON_GF_STA_PRSNT) &&
+		    (ht_opmode & IEEE80211_HT_OP_MODE_NON_HT_STA_PRSNT))
+			return -EINVAL;
+
+		switch (ht_opmode & IEEE80211_HT_OP_MODE_PROTECTION) {
+		case IEEE80211_HT_OP_MODE_PROTECTION_NONE:
+		case IEEE80211_HT_OP_MODE_PROTECTION_20MHZ:
+			if (ht_opmode & IEEE80211_HT_OP_MODE_NON_HT_STA_PRSNT)
+				return -EINVAL;
+			break;
+		case IEEE80211_HT_OP_MODE_PROTECTION_NONMEMBER:
+		case IEEE80211_HT_OP_MODE_PROTECTION_NONHT_MIXED:
+			if (!(ht_opmode & IEEE80211_HT_OP_MODE_NON_HT_STA_PRSNT))
+				return -EINVAL;
+			break;
+		}
+		cfg->ht_opmode = ht_opmode;
+	}
 	FILL_IN_MESH_PARAM_IF_SET(tb, cfg, dot11MeshHWMPactivePathToRootTimeout,
 				  1, 65535, mask,
 				  NL80211_MESHCONF_HWMP_PATH_TO_ROOT_TIMEOUT,