netfilter: nf_tables: split async and sync catchall in two functions

[ Upstream commit 8837ba3e58ea1e3d09ae36db80b1e80853aada95 ]

list_for_each_entry_safe() does not work for the async case which runs
under RCU, therefore, split GC logic for catchall in two functions
instead, one for each of the sync and async GC variants.

The catchall sync GC variant never sees a _DEAD bit set on ever, thus,
this handling is removed in such case, moreover, allocate GC sync batch
via GFP_KERNEL.

BUG=b/313503901
TEST=presubmit
RELEASE_NOTE=None

cos-patch: security-high
Fixes: 93995bf4af2c ("netfilter: nf_tables: remove catchall element in GC sync path")
Reported-by: Florian Westphal <fw@strlen.de>
Change-Id: I14126f3d22803c47c72ef943536da0832e9e985f
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Reviewed-on: https://cos-review.googlesource.com/c/third_party/kernel/+/61709
Tested-by: Cusky Presubmit Bot <presubmit@cos-infra-prod.iam.gserviceaccount.com>
Reviewed-by: Michael Kochera <kochera@google.com>
diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index 6b5f22d..34c32c8 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -9269,16 +9269,14 @@
 	call_rcu(&trans->rcu, nft_trans_gc_trans_free);
 }
 
-static struct nft_trans_gc *nft_trans_gc_catchall(struct nft_trans_gc *gc,
-						  unsigned int gc_seq,
-						  bool sync)
+struct nft_trans_gc *nft_trans_gc_catchall_async(struct nft_trans_gc *gc,
+						 unsigned int gc_seq)
 {
-	struct nft_set_elem_catchall *catchall, *next;
+	struct nft_set_elem_catchall *catchall;
 	const struct nft_set *set = gc->set;
-	struct nft_elem_priv *elem_priv;
 	struct nft_set_ext *ext;
 
-	list_for_each_entry_safe(catchall, next, &set->catchall_list, list) {
+	list_for_each_entry_rcu(catchall, &set->catchall_list, list) {
 		ext = nft_set_elem_ext(set, catchall->elem);
 
 		if (!nft_set_elem_expired(ext))
@@ -9288,39 +9286,44 @@
 
 		nft_set_elem_dead(ext);
 dead_elem:
-		if (sync)
-			gc = nft_trans_gc_queue_sync(gc, GFP_ATOMIC);
-		else
-			gc = nft_trans_gc_queue_async(gc, gc_seq, GFP_ATOMIC);
-
+		gc = nft_trans_gc_queue_async(gc, gc_seq, GFP_ATOMIC);
 		if (!gc)
 			return NULL;
 
-		elem_priv = catchall->elem;
-		if (sync) {
-			struct nft_set_elem elem = {
-				.priv = elem_priv,
-			};
-
-			nft_setelem_data_deactivate(gc->net, gc->set, &elem);
-			nft_setelem_catchall_destroy(catchall);
-		}
-
-		nft_trans_gc_elem_add(gc, elem_priv);
+		nft_trans_gc_elem_add(gc, catchall->elem);
 	}
 
 	return gc;
 }
 
-struct nft_trans_gc *nft_trans_gc_catchall_async(struct nft_trans_gc *gc,
-						 unsigned int gc_seq)
-{
-	return nft_trans_gc_catchall(gc, gc_seq, false);
-}
-
 struct nft_trans_gc *nft_trans_gc_catchall_sync(struct nft_trans_gc *gc)
 {
-	return nft_trans_gc_catchall(gc, 0, true);
+	struct nft_set_elem_catchall *catchall, *next;
+	const struct nft_set *set = gc->set;
+	struct nft_set_elem elem;
+	struct nft_set_ext *ext;
+
+	WARN_ON_ONCE(!lockdep_commit_lock_is_held(gc->net));
+
+	list_for_each_entry_safe(catchall, next, &set->catchall_list, list) {
+		ext = nft_set_elem_ext(set, catchall->elem);
+
+		if (!nft_set_elem_expired(ext))
+			continue;
+
+		gc = nft_trans_gc_queue_sync(gc, GFP_KERNEL);
+		if (!gc)
+			return NULL;
+
+		memset(&elem, 0, sizeof(elem));
+		elem.priv = catchall->elem;
+
+		nft_setelem_data_deactivate(gc->net, gc->set, &elem);
+		nft_setelem_catchall_destroy(catchall);
+		nft_trans_gc_elem_add(gc, elem.priv);
+	}
+
+	return gc;
 }
 
 static void nf_tables_module_autoload_cleanup(struct net *net)