diff mbox series

[net-next,07/14] netfilter: nf_tables: Tolerate chains with no remaining hooks

Message ID 20250116171902.1783620-8-pablo@netfilter.org (mailing list archive)
State New
Delegated to: Netdev Maintainers
Headers show
Series [net-next,01/14] netfilter: nf_tables: fix set size with rbtree backend | expand

Checks

Context Check Description
netdev/series_format success Pull request is its own cover letter
netdev/tree_selection success Clearly marked for net-next
netdev/ynl success Generated files up to date; no warnings/errors; no diff in generated;
netdev/fixes_present success Fixes tag not required for -next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 1 this patch: 1
netdev/build_tools success Errors and warnings before: 0 (+1) this patch: 0 (+1)
netdev/cc_maintainers warning 3 maintainers not CCed: coreteam@netfilter.org horms@kernel.org kadlec@netfilter.org
netdev/build_clang success Errors and warnings before: 70 this patch: 70
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/deprecated_api success None detected
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success No Fixes tag
netdev/build_allmodconfig_warn success Errors and warnings before: 54 this patch: 54
netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 96 lines checked
netdev/build_clang_rust success No Rust files in patch. Skipping build
netdev/kdoc success Errors and warnings before: 9 this patch: 9
netdev/source_inline success Was 0 now: 0

Commit Message

Pablo Neira Ayuso Jan. 16, 2025, 5:18 p.m. UTC 
From: Phil Sutter <phil@nwl.cc>

Do not drop a netdev-family chain if the last interface it is registered
for vanishes. Users dumping and storing the ruleset upon shutdown to
restore it upon next boot may otherwise lose the chain and all contained
rules. They will still lose the list of devices, a later patch will fix
that. For now, this aligns the event handler's behaviour with that for
flowtables.
The controversal situation at netns exit should be no problem here:
event handler will unregister the hooks, core nftables cleanup code will
drop the chain itself.

Signed-off-by: Phil Sutter <phil@nwl.cc>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
 include/net/netfilter/nf_tables.h |  2 --
 net/netfilter/nf_tables_api.c     | 41 -------------------------------
 net/netfilter/nft_chain_filter.c  | 29 ++++++----------------
 3 files changed, 7 insertions(+), 65 deletions(-)
diff mbox series

Patch

diff --git a/include/net/netfilter/nf_tables.h b/include/net/netfilter/nf_tables.h
index d1f274af5b70..26a65d5a3123 100644
--- a/include/net/netfilter/nf_tables.h
+++ b/include/net/netfilter/nf_tables.h
@@ -1235,8 +1235,6 @@  static inline bool nft_is_base_chain(const struct nft_chain *chain)
 	return chain->flags & NFT_CHAIN_BASE;
 }
 
-int __nft_release_basechain(struct nft_ctx *ctx);
-
 unsigned int nft_do_chain(struct nft_pktinfo *pkt, void *priv);
 
 static inline bool nft_use_inc(u32 *use)
diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index ed15c52e3c65..667459256e4c 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -11741,47 +11741,6 @@  int nft_data_dump(struct sk_buff *skb, int attr, const struct nft_data *data,
 }
 EXPORT_SYMBOL_GPL(nft_data_dump);
 
-static void __nft_release_basechain_now(struct nft_ctx *ctx)
-{
-	struct nft_rule *rule, *nr;
-
-	list_for_each_entry_safe(rule, nr, &ctx->chain->rules, list) {
-		list_del(&rule->list);
-		nf_tables_rule_release(ctx, rule);
-	}
-	nf_tables_chain_destroy(ctx->chain);
-}
-
-int __nft_release_basechain(struct nft_ctx *ctx)
-{
-	struct nft_rule *rule;
-
-	if (WARN_ON_ONCE(!nft_is_base_chain(ctx->chain)))
-		return 0;
-
-	nf_tables_unregister_hook(ctx->net, ctx->chain->table, ctx->chain);
-	list_for_each_entry(rule, &ctx->chain->rules, list)
-		nft_use_dec(&ctx->chain->use);
-
-	nft_chain_del(ctx->chain);
-	nft_use_dec(&ctx->table->use);
-
-	if (!maybe_get_net(ctx->net)) {
-		__nft_release_basechain_now(ctx);
-		return 0;
-	}
-
-	/* wait for ruleset dumps to complete.  Owning chain is no longer in
-	 * lists, so new dumps can't find any of these rules anymore.
-	 */
-	synchronize_rcu();
-
-	__nft_release_basechain_now(ctx);
-	put_net(ctx->net);
-	return 0;
-}
-EXPORT_SYMBOL_GPL(__nft_release_basechain);
-
 static void __nft_release_hook(struct net *net, struct nft_table *table)
 {
 	struct nft_flowtable *flowtable;
diff --git a/net/netfilter/nft_chain_filter.c b/net/netfilter/nft_chain_filter.c
index 7010541fcca6..543f258b7c6b 100644
--- a/net/netfilter/nft_chain_filter.c
+++ b/net/netfilter/nft_chain_filter.c
@@ -322,34 +322,19 @@  static void nft_netdev_event(unsigned long event, struct net_device *dev,
 			     struct nft_ctx *ctx)
 {
 	struct nft_base_chain *basechain = nft_base_chain(ctx->chain);
-	struct nft_hook *hook, *found = NULL;
-	int n = 0;
+	struct nft_hook *hook;
 
 	list_for_each_entry(hook, &basechain->hook_list, list) {
-		if (hook->ops.dev == dev)
-			found = hook;
-
-		n++;
-	}
-	if (!found)
-		return;
+		if (hook->ops.dev != dev)
+			continue;
 
-	if (n > 1) {
 		if (!(ctx->chain->table->flags & NFT_TABLE_F_DORMANT))
-			nf_unregister_net_hook(ctx->net, &found->ops);
+			nf_unregister_net_hook(ctx->net, &hook->ops);
 
-		list_del_rcu(&found->list);
-		kfree_rcu(found, rcu);
-		return;
+		list_del_rcu(&hook->list);
+		kfree_rcu(hook, rcu);
+		break;
 	}
-
-	/* UNREGISTER events are also happening on netns exit.
-	 *
-	 * Although nf_tables core releases all tables/chains, only this event
-	 * handler provides guarantee that hook->ops.dev is still accessible,
-	 * so we cannot skip exiting net namespaces.
-	 */
-	__nft_release_basechain(ctx);
 }
 
 static int nf_tables_netdev_event(struct notifier_block *this,