netfilter: nf_tables: honor NLM_F_EXCL flag in set element insertion

If the NLM_F_EXCL flag is set, then new elements that clash with an
existing one return EEXIST. In case you try to add an element whose
data area differs from what we have, then this returns EBUSY. If no
flag is specified at all, then this returns success to userspace.

This patch also update the set insert operation so we can fetch the
existing element that clashes with the one you want to add, we need
this to make sure the element data doesn't differ.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

1 files changed, 8 insertions, 4 deletions

diff --git a/net/netfilter/nft_set_rbtree.c b/net/netfilter/nft_set_rbtree.c
index 6473936d05c6..038682d48261 100644
--- a/net/netfilter/nft_set_rbtree.c
+++ b/net/netfilter/nft_set_rbtree.c
@@ -94,7 +94,8 @@ out:
 }
 
 static int __nft_rbtree_insert(const struct net *net, const struct nft_set *set,
-			       struct nft_rbtree_elem *new)
+			       struct nft_rbtree_elem *new,
+			       struct nft_set_ext **ext)
 {
 	struct nft_rbtree *priv = nft_set_priv(set);
 	u8 genmask = nft_genmask_next(net);
@@ -122,8 +123,10 @@ static int __nft_rbtree_insert(const struct net *net, const struct nft_set *set,
 				else if (!nft_rbtree_interval_end(rbe) &&
 					 nft_rbtree_interval_end(new))
 					p = &parent->rb_right;
-				else
+				else {
+					*ext = &rbe->ext;
 					return -EEXIST;
+				}
 			}
 		}
 	}
@@ -133,13 +136,14 @@ static int __nft_rbtree_insert(const struct net *net, const struct nft_set *set,
 }
 
 static int nft_rbtree_insert(const struct net *net, const struct nft_set *set,
-			     const struct nft_set_elem *elem)
+			     const struct nft_set_elem *elem,
+			     struct nft_set_ext **ext)
 {
 	struct nft_rbtree_elem *rbe = elem->priv;
 	int err;
 
 	spin_lock_bh(&nft_rbtree_lock);
-	err = __nft_rbtree_insert(net, set, rbe);
+	err = __nft_rbtree_insert(net, set, rbe, ext);
 	spin_unlock_bh(&nft_rbtree_lock);
 
 	return err;