cfg80211: More error messages for key addition failures

These were helpful while working with extensions to NL80211_CMD_NEW_KEY,
so add more explicit error reporting for additional cases that can fail
while that command is being processed.

Signed-off-by: Jouni Malinen <jouni@codeaurora.org>
Link: https://lore.kernel.org/r/20200222132548.20835-1-jouni@codeaurora.org
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

net/wireless/nl80211.c

@@ -3978,8 +3978,10 @@ static int nl80211_new_key(struct sk_buff *skb, struct genl_info *info)
 	if (err)
 		return err;
 
-	if (!key.p.key)
+	if (!key.p.key) {
+		GENL_SET_ERR_MSG(info, "no key");
 		return -EINVAL;
+	}
 
 	if (info->attrs[NL80211_ATTR_MAC])
 		mac_addr = nla_data(info->attrs[NL80211_ATTR_MAC]);
@@ -3993,8 +3995,10 @@ static int nl80211_new_key(struct sk_buff *skb, struct genl_info *info)
 
 	/* for now */
 	if (key.type != NL80211_KEYTYPE_PAIRWISE &&
-	    key.type != NL80211_KEYTYPE_GROUP)
+	    key.type != NL80211_KEYTYPE_GROUP) {
+		GENL_SET_ERR_MSG(info, "key type not pairwise or group");
 		return -EINVAL;
+	}
 
 	if (key.type == NL80211_KEYTYPE_GROUP &&
 	    info->attrs[NL80211_ATTR_VLAN_ID])
@@ -4005,15 +4009,22 @@ static int nl80211_new_key(struct sk_buff *skb, struct genl_info *info)
 
 	if (cfg80211_validate_key_settings(rdev, &key.p, key.idx,
 					   key.type == NL80211_KEYTYPE_PAIRWISE,
-					   mac_addr))
+					   mac_addr)) {
+		GENL_SET_ERR_MSG(info, "key setting validation failed");
 		return -EINVAL;
+	}
 
 	wdev_lock(dev->ieee80211_ptr);
 	err = nl80211_key_allowed(dev->ieee80211_ptr);
-	if (!err)
+	if (err)
+		GENL_SET_ERR_MSG(info, "key not allowed");
+	if (!err) {
 		err = rdev_add_key(rdev, dev, key.idx,
 				   key.type == NL80211_KEYTYPE_PAIRWISE,
 				    mac_addr, &key.p);
+		if (err)
+			GENL_SET_ERR_MSG(info, "key addition failed");
+	}
 	wdev_unlock(dev->ieee80211_ptr);
 
 	return err;