netfilter: nf_tables: check if same extensions are set when adding elements

If no NLM_F_EXCL is set and the element already exists in the set, make
sure that both elements have the same extensions.

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

1 files changed, 5 insertions, 0 deletions

diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index 434c739dfeca..11a96e8dd3cd 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -3749,6 +3749,11 @@ static int nft_add_set_elem(struct nft_ctx *ctx, struct nft_set *set,
         err = set->ops->insert(ctx->net, set, &elem, &ext2);
         if (err) {
                 if (err == -EEXIST) {
+                        if (nft_set_ext_exists(ext, NFT_SET_EXT_DATA) ^
+                            nft_set_ext_exists(ext2, NFT_SET_EXT_DATA) ||
+                            nft_set_ext_exists(ext, NFT_SET_EXT_OBJREF) ^
+                            nft_set_ext_exists(ext2, NFT_SET_EXT_OBJREF))
+                                return -EBUSY;
                         if ((nft_set_ext_exists(ext, NFT_SET_EXT_DATA) &&
                              nft_set_ext_exists(ext2, NFT_SET_EXT_DATA) &&
                              memcmp(nft_set_ext_data(ext),