netfilter: nf_tables: missing extended netlink error in lookup functions

Set netlink extended error reporting for several lookup functions which
allows userspace to infer what is the error cause.
Reported-by: Phil Sutter <phil@nwl.cc>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Florian Westphal <fw@strlen.de>

net/netfilter/nf_tables_api.c

@@ -4695,8 +4695,10 @@ static int nf_tables_getset(struct sk_buff *skb, const struct nfnl_info *info,
 		return -EINVAL;
 
 	set = nft_set_lookup(table, nla[NFTA_SET_NAME], genmask);
-	if (IS_ERR(set))
+	if (IS_ERR(set)) {
+		NL_SET_BAD_ATTR(extack, nla[NFTA_SET_NAME]);
 		return PTR_ERR(set);
+	}
 
 	skb2 = alloc_skb(NLMSG_GOODSIZE, GFP_ATOMIC);
 	if (skb2 == NULL)
@@ -6025,8 +6027,10 @@ static int nf_tables_getsetelem(struct sk_buff *skb,
 	}
 
 	set = nft_set_lookup(table, nla[NFTA_SET_ELEM_LIST_SET], genmask);
-	if (IS_ERR(set))
+	if (IS_ERR(set)) {
+		NL_SET_BAD_ATTR(extack, nla[NFTA_SET_ELEM_LIST_SET]);
 		return PTR_ERR(set);
+	}
 
 	nft_ctx_init(&ctx, net, skb, info->nlh, family, table, NULL, nla);
 
@@ -6919,8 +6923,10 @@ static int nf_tables_newsetelem(struct sk_buff *skb,
 
 	set = nft_set_lookup_global(net, table, nla[NFTA_SET_ELEM_LIST_SET],
 				    nla[NFTA_SET_ELEM_LIST_SET_ID], genmask);
-	if (IS_ERR(set))
+	if (IS_ERR(set)) {
+		NL_SET_BAD_ATTR(extack, nla[NFTA_SET_ELEM_LIST_SET]);
 		return PTR_ERR(set);
+	}
 
 	if (!list_empty(&set->bindings) &&
 	    (set->flags & (NFT_SET_CONSTANT | NFT_SET_ANONYMOUS)))
@@ -7195,8 +7201,10 @@ static int nf_tables_delsetelem(struct sk_buff *skb,
 	}
 
 	set = nft_set_lookup(table, nla[NFTA_SET_ELEM_LIST_SET], genmask);
-	if (IS_ERR(set))
+	if (IS_ERR(set)) {
+		NL_SET_BAD_ATTR(extack, nla[NFTA_SET_ELEM_LIST_SET]);
 		return PTR_ERR(set);
+	}
 
 	if (nft_set_is_anonymous(set))
 		return -EOPNOTSUPP;
@@ -8680,6 +8688,7 @@ static int nf_tables_getflowtable(struct sk_buff *skb,
 				  const struct nfnl_info *info,
 				  const struct nlattr * const nla[])
 {
+	struct netlink_ext_ack *extack = info->extack;
 	u8 genmask = nft_genmask_cur(info->net);
 	u8 family = info->nfmsg->nfgen_family;
 	struct nft_flowtable *flowtable;
@@ -8705,13 +8714,17 @@ static int nf_tables_getflowtable(struct sk_buff *skb,
 
 	table = nft_table_lookup(net, nla[NFTA_FLOWTABLE_TABLE], family,
 				 genmask, 0);
-	if (IS_ERR(table))
+	if (IS_ERR(table)) {
+		NL_SET_BAD_ATTR(extack, nla[NFTA_FLOWTABLE_TABLE]);
 		return PTR_ERR(table);
+	}
 
 	flowtable = nft_flowtable_lookup(table, nla[NFTA_FLOWTABLE_NAME],
 					 genmask);
-	if (IS_ERR(flowtable))
+	if (IS_ERR(flowtable)) {
+		NL_SET_BAD_ATTR(extack, nla[NFTA_FLOWTABLE_NAME]);
 		return PTR_ERR(flowtable);
+	}
 
 	skb2 = alloc_skb(NLMSG_GOODSIZE, GFP_ATOMIC);
 	if (!skb2)