[PATCH bpf v2 1/2] bpf: Extract shared reqsk-to-listener upgrade

[Michal Luczaj]

__bpf_sk_lookup() and bpf_sk_lookup() duplicate the same sk_to_full_sk()
reqsk-to-listener upgrade. Extract it into a helper.

Leave the currently unreachable WARN_ONCE as a defensive assert.

No functional change.

Signed-off-by: Michal Luczaj <mhal@xxxxxxx>
Reviewed-by: Emil Tsalapatis <emil@xxxxxxxxxxxxxxx>
---
 net/core/filter.c | 58 +++++++++++++++++++++++++------------------------------
 1 file changed, 26 insertions(+), 32 deletions(-)

diff --git a/net/core/filter.c b/net/core/filter.c
index 11bb0d236822..fede810ef37f 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -7079,6 +7079,28 @@ __bpf_skc_lookup(struct sk_buff *skb, struct bpf_sock_tuple *tuple, u32 len,
 	return sk;
 }
 
+static struct sock *
+bpf_sk_lookup_full_sk(struct sock *sk)
+{
+	struct sock *sk2 = sk_to_full_sk(sk);
+
+	/*
+	 * sk_to_full_sk() may return sk->rsk_listener, make sure the original
+	 * sk sock refcnt is decremented to prevent a request_sock leak.
+	 */
+	if (sk2 != sk) {
+		sock_gen_put(sk);
+		/* Ensure there is no need to bump sk2 refcnt. */
+		if (unlikely(sk2 && !sock_flag(sk2, SOCK_RCU_FREE))) {
+			WARN_ONCE(1, "Found non-RCU, unreferenced socket!");
+			return NULL;
+		}
+		sk = sk2;
+	}
+
+	return sk;
+}
+
 static struct sock *
 __bpf_sk_lookup(struct sk_buff *skb, struct bpf_sock_tuple *tuple, u32 len,
 		struct net *caller_net, u32 ifindex, u8 proto, u64 netns_id,
@@ -7088,22 +7110,8 @@ __bpf_sk_lookup(struct sk_buff *skb, struct bpf_sock_tuple *tuple, u32 len,
 					   ifindex, proto, netns_id, flags,
 					   sdif);
 
-	if (sk) {
-		struct sock *sk2 = sk_to_full_sk(sk);
-
-		/* sk_to_full_sk() may return (sk)->rsk_listener, so make sure the original sk
-		 * sock refcnt is decremented to prevent a request_sock leak.
-		 */
-		if (sk2 != sk) {
-			sock_gen_put(sk);
-			/* Ensure there is no need to bump sk2 refcnt */
-			if (unlikely(sk2 && !sock_flag(sk2, SOCK_RCU_FREE))) {
-				WARN_ONCE(1, "Found non-RCU, unreferenced socket!");
-				return NULL;
-			}
-			sk = sk2;
-		}
-	}
+	if (sk)
+		sk = bpf_sk_lookup_full_sk(sk);
 
 	return sk;
 }
@@ -7134,22 +7142,8 @@ bpf_sk_lookup(struct sk_buff *skb, struct bpf_sock_tuple *tuple, u32 len,
 	struct sock *sk = bpf_skc_lookup(skb, tuple, len, proto, netns_id,
 					 flags);
 
-	if (sk) {
-		struct sock *sk2 = sk_to_full_sk(sk);
-
-		/* sk_to_full_sk() may return (sk)->rsk_listener, so make sure the original sk
-		 * sock refcnt is decremented to prevent a request_sock leak.
-		 */
-		if (sk2 != sk) {
-			sock_gen_put(sk);
-			/* Ensure there is no need to bump sk2 refcnt */
-			if (unlikely(sk2 && !sock_flag(sk2, SOCK_RCU_FREE))) {
-				WARN_ONCE(1, "Found non-RCU, unreferenced socket!");
-				return NULL;
-			}
-			sk = sk2;
-		}
-	}
+	if (sk)
+		sk = bpf_sk_lookup_full_sk(sk);
 
 	return sk;
 }

-- 
2.55.0