[PATCH 4.19 04/91] netfilter: nf_tables: disallow element removal on anonymous sets

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

4.19-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Pablo Neira Ayuso <pablo@netfilter.org>

[ Upstream commit 23a3bfd4ba7acd36abf52b78605f61b21bdac216 ]

Anonymous sets need to be populated once at creation and then they are
bound to rule since 938154b93be8 ("netfilter: nf_tables: reject unbound
anonymous set before commit phase"), otherwise transaction reports
EINVAL.

Userspace does not need to delete elements of anonymous sets that are
not yet bound, reject this with EOPNOTSUPP.

>From flush command path, skip anonymous sets, they are expected to be
bound already. Otherwise, EINVAL is hit at the end of this transaction
for unbound sets.

Fixes: 96518518cc41 ("netfilter: add nftables")
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 net/netfilter/nf_tables_api.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index 0ff8f1006c6b9..3e30441162896 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -993,8 +993,7 @@ static int nft_flush_table(struct nft_ctx *ctx)
 		if (!nft_is_active_next(ctx->net, set))
 			continue;
 
-		if (nft_set_is_anonymous(set) &&
-		    !list_empty(&set->bindings))
+		if (nft_set_is_anonymous(set))
 			continue;
 
 		err = nft_delset(ctx, set);
@@ -4902,8 +4901,10 @@ static int nf_tables_delsetelem(struct net *net, struct sock *nlsk,
 	if (IS_ERR(set))
 		return PTR_ERR(set);
 
-	if (!list_empty(&set->bindings) &&
-	    (set->flags & (NFT_SET_CONSTANT | NFT_SET_ANONYMOUS)))
+	if (nft_set_is_anonymous(set))
+		return -EOPNOTSUPP;
+
+	if (!list_empty(&set->bindings) && (set->flags & NFT_SET_CONSTANT))
 		return -EBUSY;
 
 	if (nla[NFTA_SET_ELEM_LIST_ELEMENTS] == NULL) {
-- 
2.40.1