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

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Message-Id: <20210306121223.28711-8-pablo@netfilter.org>
Date:   Sat,  6 Mar 2021 13:12:21 +0100
From:   Pablo Neira Ayuso <pablo@...filter.org>
To:     netfilter-devel@...r.kernel.org
Cc:     davem@...emloft.net, netdev@...r.kernel.org, kuba@...nel.org
Subject: [PATCH net 7/9] netfilter: nftables: disallow updates on table ownership

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 <pablo@...filter.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