1 files changed, 36 insertions, 13 deletions

diff --git a/net/core/lwtunnel.c b/net/core/lwtunnel.c
index c23465005f2f..d9cb3532f1dd 100644
--- a/net/core/lwtunnel.c
+++ b/net/core/lwtunnel.c
@@ -101,39 +101,55 @@ int lwtunnel_encap_del_ops(const struct lwtunnel_encap_ops *ops,
 }
 EXPORT_SYMBOL(lwtunnel_encap_del_ops);
 
-int lwtunnel_build_state(struct net_device *dev, u16 encap_type,
+int lwtunnel_build_state(u16 encap_type,
 			 struct nlattr *encap, unsigned int family,
-			 const void *cfg, struct lwtunnel_state **lws)
+			 const void *cfg, struct lwtunnel_state **lws,
+			 struct netlink_ext_ack *extack)
 {
 	const struct lwtunnel_encap_ops *ops;
+	bool found = false;
 	int ret = -EINVAL;
 
 	if (encap_type == LWTUNNEL_ENCAP_NONE ||
-	    encap_type > LWTUNNEL_ENCAP_MAX)
+	    encap_type > LWTUNNEL_ENCAP_MAX) {
+		NL_SET_ERR_MSG_ATTR(extack, encap,
+				    "Unknown LWT encapsulation type");
 		return ret;
+	}
 
 	ret = -EOPNOTSUPP;
 	rcu_read_lock();
 	ops = rcu_dereference(lwtun_encaps[encap_type]);
 	if (likely(ops && ops->build_state && try_module_get(ops->owner))) {
-		ret = ops->build_state(dev, encap, family, cfg, lws);
+		found = true;
+		ret = ops->build_state(encap, family, cfg, lws, extack);
 		if (ret)
 			module_put(ops->owner);
 	}
 	rcu_read_unlock();
 
+	/* don't rely on -EOPNOTSUPP to detect match as build_state
+	 * handlers could return it
+	 */
+	if (!found) {
+		NL_SET_ERR_MSG_ATTR(extack, encap,
+				    "LWT encapsulation type not supported");
+	}
+
 	return ret;
 }
 EXPORT_SYMBOL(lwtunnel_build_state);
 
-int lwtunnel_valid_encap_type(u16 encap_type)
+int lwtunnel_valid_encap_type(u16 encap_type, struct netlink_ext_ack *extack)
 {
 	const struct lwtunnel_encap_ops *ops;
 	int ret = -EINVAL;
 
 	if (encap_type == LWTUNNEL_ENCAP_NONE ||
-	    encap_type > LWTUNNEL_ENCAP_MAX)
+	    encap_type > LWTUNNEL_ENCAP_MAX) {
+		NL_SET_ERR_MSG(extack, "Unknown lwt encapsulation type");
 		return ret;
+	}
 
 	rcu_read_lock();
 	ops = rcu_dereference(lwtun_encaps[encap_type]);
@@ -153,16 +169,20 @@ int lwtunnel_valid_encap_type(u16 encap_type)
 		}
 	}
 #endif
-	return ops ? 0 : -EOPNOTSUPP;
+	ret = ops ? 0 : -EOPNOTSUPP;
+	if (ret < 0)
+		NL_SET_ERR_MSG(extack, "lwt encapsulation type not supported");
+
+	return ret;
 }
 EXPORT_SYMBOL(lwtunnel_valid_encap_type);
 
-int lwtunnel_valid_encap_type_attr(struct nlattr *attr, int remaining)
+int lwtunnel_valid_encap_type_attr(struct nlattr *attr, int remaining,
+				   struct netlink_ext_ack *extack)
 {
 	struct rtnexthop *rtnh = (struct rtnexthop *)attr;
 	struct nlattr *nla_entype;
 	struct nlattr *attrs;
-	struct nlattr *nla;
 	u16 encap_type;
 	int attrlen;
 
@@ -170,13 +190,13 @@ int lwtunnel_valid_encap_type_attr(struct nlattr *attr, int remaining)
 		attrlen = rtnh_attrlen(rtnh);
 		if (attrlen > 0) {
 			attrs = rtnh_attrs(rtnh);
-			nla = nla_find(attrs, attrlen, RTA_ENCAP);
 			nla_entype = nla_find(attrs, attrlen, RTA_ENCAP_TYPE);
 
 			if (nla_entype) {
 				encap_type = nla_get_u16(nla_entype);
 
-				if (lwtunnel_valid_encap_type(encap_type) != 0)
+				if (lwtunnel_valid_encap_type(encap_type,
+							      extack) != 0)
 					return -EOPNOTSUPP;
 			}
 		}
@@ -205,7 +225,7 @@ int lwtunnel_fill_encap(struct sk_buff *skb, struct lwtunnel_state *lwtstate)
 {
 	const struct lwtunnel_encap_ops *ops;
 	struct nlattr *nest;
-	int ret = -EINVAL;
+	int ret;
 
 	if (!lwtstate)
 		return 0;
@@ -214,8 +234,11 @@ int lwtunnel_fill_encap(struct sk_buff *skb, struct lwtunnel_state *lwtstate)
 	    lwtstate->type > LWTUNNEL_ENCAP_MAX)
 		return 0;
 
-	ret = -EOPNOTSUPP;
 	nest = nla_nest_start(skb, RTA_ENCAP);
+	if (!nest)
+		return -EMSGSIZE;
+
+	ret = -EOPNOTSUPP;
 	rcu_read_lock();
 	ops = rcu_dereference(lwtun_encaps[lwtstate->type]);
 	if (likely(ops && ops->fill_encap))