netdev - [PATCH net 1/3] netfilter: nf_tables: disable toggling dormant table state more than once

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Date: Wed, 20 Sep 2023 10:41:49 +0200
From: Florian Westphal <fw@...len.de>
To: <netdev@...r.kernel.org>
Cc: Paolo Abeni <pabeni@...hat.com>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>,
	<netfilter-devel@...r.kernel.org>,
	"Lee, Cherie-Anne" <cherie.lee@...rlabs.sg>,
	Bing-Jhong Billy Jheng <billy@...rlabs.sg>,
	info@...rlabs.sg
Subject: [PATCH net 1/3] netfilter: nf_tables: disable toggling dormant table state more than once

nft -f -<<EOF
add table ip t
add table ip t { flags dormant; }
add chain ip t c { type filter hook input priority 0; }
add table ip t
EOF

Triggers a splat from nf core on next table delete because we lose
track of right hook register state:

WARNING: CPU: 2 PID: 1597 at net/netfilter/core.c:501 __nf_unregister_net_hook
RIP: 0010:__nf_unregister_net_hook+0x41b/0x570
 nf_unregister_net_hook+0xb4/0xf0
 __nf_tables_unregister_hook+0x160/0x1d0
[..]

The above should have table in *active* state, but in fact no
hooks were registered.

Reject on/off/on games rather than attempting to fix this.

Fixes: 179d9ba5559a ("netfilter: nf_tables: fix table flag updates")
Reported-by: "Lee, Cherie-Anne" <cherie.lee@...rlabs.sg>
Cc: Bing-Jhong Billy Jheng <billy@...rlabs.sg>
Cc: info@...rlabs.sg
Signed-off-by: Florian Westphal <fw@...len.de>
---
 net/netfilter/nf_tables_api.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index d819b4d42962..a3680638ec60 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -1219,6 +1219,10 @@ static int nf_tables_updtable(struct nft_ctx *ctx)
 	     flags & NFT_TABLE_F_OWNER))
 		return -EOPNOTSUPP;
 
+	/* No dormant off/on/off/on games in single transaction */
+	if (ctx->table->flags & __NFT_TABLE_F_UPDATE)
+		return -EINVAL;
+
 	trans = nft_trans_alloc(ctx, NFT_MSG_NEWTABLE,
 				sizeof(struct nft_trans_table));
 	if (trans == NULL)
-- 
2.41.0