[PATCH net 7/9] netfilter: nftables: disallow updates on table ownership

[Pablo Neira Ayuso]

Disallow updating the ownership bit on an existing table: Do not allow
to grab ownership on an existing table. Do not allow to drop ownership
on an existing table.

Fixes: 6001a930ce03 ("netfilter: nftables: introduce table ownership")
Signed-off-by: Pablo Neira Ayuso <pa...@netfilter.org>
---
 net/netfilter/nf_tables_api.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index c1eb5cdb3033..b07703e19108 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -916,6 +916,12 @@ static int nf_tables_updtable(struct nft_ctx *ctx)
        if (flags == ctx->table->flags)
                return 0;
 
+       if ((nft_table_has_owner(ctx->table) &&
+            !(flags & NFT_TABLE_F_OWNER)) ||
+           (!nft_table_has_owner(ctx->table) &&
+            flags & NFT_TABLE_F_OWNER))
+               return -EOPNOTSUPP;
+
        trans = nft_trans_alloc(ctx, NFT_MSG_NEWTABLE,
                                sizeof(struct nft_trans_table));
        if (trans == NULL)
-- 
2.20.1