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@starlabs.sg>
Cc: Bing-Jhong Billy Jheng <billy@starlabs.sg>
Cc: info@starlabs.sg
Signed-off-by: Florian Westphal <fw@strlen.de>

diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index d819b4d429624da87366d6ad9173f0cedc49ae73..a3680638ec60f7d1fd47daf44283e043b6cb6088 100644 (file)
--- 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)