Re: [PATCH] [net-next] netfilter: bridge: make NF_TABLES_BRIDGE tristate

[Pablo Neira Ayuso]

On Thu, Jul 18, 2019 at 09:01:10PM +0200, Pablo Neira Ayuso wrote:
> On Wed, Jul 10, 2019 at 10:08:20AM +0200, Arnd Bergmann wrote:
> > The new nft_meta_bridge code fails to link as built-in when NF_TABLES
> > is a loadable module.
> > 
> > net/bridge/netfilter/nft_meta_bridge.o: In function `nft_meta_bridge_get_eval':
> > nft_meta_bridge.c:(.text+0x1e8): undefined reference to `nft_meta_get_eval'
> > net/bridge/netfilter/nft_meta_bridge.o: In function `nft_meta_bridge_get_init':
> > nft_meta_bridge.c:(.text+0x468): undefined reference to `nft_meta_get_init'
> > nft_meta_bridge.c:(.text+0x49c): undefined reference to `nft_parse_register'
> > nft_meta_bridge.c:(.text+0x4cc): undefined reference to `nft_validate_register_store'
> > net/bridge/netfilter/nft_meta_bridge.o: In function `nft_meta_bridge_module_exit':
> > nft_meta_bridge.c:(.exit.text+0x14): undefined reference to `nft_unregister_expr'
> > net/bridge/netfilter/nft_meta_bridge.o: In function `nft_meta_bridge_module_init':
> > nft_meta_bridge.c:(.init.text+0x14): undefined reference to `nft_register_expr'
> > net/bridge/netfilter/nft_meta_bridge.o:(.rodata+0x60): undefined reference to `nft_meta_get_dump'
> > net/bridge/netfilter/nft_meta_bridge.o:(.rodata+0x88): undefined reference to `nft_meta_set_eval'
> > 
> > This can happen because the NF_TABLES_BRIDGE dependency itself is just a
> > 'bool'.  Make the symbol a 'tristate' instead so Kconfig can propagate the
> > dependencies correctly.
> 
> Hm. Something breaks here. Investigating. Looks like bridge support is
> gone after this, nft fails to register the filter chain type:
> 
> # nft add table bridge x
> # nft add chain bridge x y { type filter hook input priority 0\; }
> Error: Could not process rule: No such file or directory

Found it. It seems this patch is needed, on top of your patch.

I can just squash this chunk into your original patch and push it out
if you're OK witht this.

Thanks.
diff --git a/net/netfilter/nft_chain_filter.c b/net/netfilter/nft_chain_filter.c
index 3fd540b2c6ba..b5d5d071d765 100644
--- a/net/netfilter/nft_chain_filter.c
+++ b/net/netfilter/nft_chain_filter.c
@@ -193,7 +193,7 @@ static inline void nft_chain_filter_inet_init(void) {}
 static inline void nft_chain_filter_inet_fini(void) {}
 #endif /* CONFIG_NF_TABLES_IPV6 */
 
-#ifdef CONFIG_NF_TABLES_BRIDGE
+#if IS_ENABLED(CONFIG_NF_TABLES_BRIDGE)
 static unsigned int
 nft_do_chain_bridge(void *priv,
 		    struct sk_buff *skb,