net: add TIME_WAIT logic to sk_to_full_sk()

TCP will soon attach TIME_WAIT sockets to some ACK and RST.

Make sure sk_to_full_sk() detects this and does not return
a non full socket.

v3: also changed sk_const_to_full_sk()

Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Reviewed-by: Martin KaFai Lau <martin.lau@kernel.org>
Reviewed-by: Brian Vazquez <brianvv@google.com>
Link: https://patch.msgid.link/20241010174817.1543642-2-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

include/linux/bpf-cgroup.h

@@ -209,7 +209,7 @@ static inline bool cgroup_bpf_sock_enabled(struct sock *sk,
 	int __ret = 0;							       \
 	if (cgroup_bpf_enabled(CGROUP_INET_EGRESS) && sk) {		       \
 		typeof(sk) __sk = sk_to_full_sk(sk);			       \
-		if (sk_fullsock(__sk) && __sk == skb_to_full_sk(skb) &&	       \
+		if (__sk && __sk == skb_to_full_sk(skb) &&	       \
 		    cgroup_bpf_sock_enabled(__sk, CGROUP_INET_EGRESS))	       \
 			__ret = __cgroup_bpf_run_filter_skb(__sk, skb,	       \
 						      CGROUP_INET_EGRESS); \

include/net/inet_sock.h

@@ -321,8 +321,10 @@ static inline unsigned long inet_cmsg_flags(const struct inet_sock *inet)
 static inline struct sock *sk_to_full_sk(struct sock *sk)
 {
 #ifdef CONFIG_INET
-	if (sk && sk->sk_state == TCP_NEW_SYN_RECV)
+	if (sk && READ_ONCE(sk->sk_state) == TCP_NEW_SYN_RECV)
 		sk = inet_reqsk(sk)->rsk_listener;
+	if (sk && READ_ONCE(sk->sk_state) == TCP_TIME_WAIT)
+		sk = NULL;
 #endif
 	return sk;
 }
@@ -331,8 +333,10 @@ static inline struct sock *sk_to_full_sk(struct sock *sk)
 static inline const struct sock *sk_const_to_full_sk(const struct sock *sk)
 {
 #ifdef CONFIG_INET
-	if (sk && sk->sk_state == TCP_NEW_SYN_RECV)
+	if (sk && READ_ONCE(sk->sk_state) == TCP_NEW_SYN_RECV)
 		sk = ((const struct request_sock *)sk)->rsk_listener;
+	if (sk && READ_ONCE(sk->sk_state) == TCP_TIME_WAIT)
+		sk = NULL;
 #endif
 	return sk;
 }

net/core/filter.c

@@ -6778,8 +6778,6 @@ __bpf_sk_lookup(struct sk_buff *skb, struct bpf_sock_tuple *tuple, u32 len,
 		/* 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 (!sk_fullsock(sk2))
-			sk2 = NULL;
 		if (sk2 != sk) {
 			sock_gen_put(sk);
 			/* Ensure there is no need to bump sk2 refcnt */
@@ -6826,8 +6824,6 @@ bpf_sk_lookup(struct sk_buff *skb, struct bpf_sock_tuple *tuple, u32 len,
 		/* 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 (!sk_fullsock(sk2))
-			sk2 = NULL;
 		if (sk2 != sk) {
 			sock_gen_put(sk);
 			/* Ensure there is no need to bump sk2 refcnt */
@@ -7276,7 +7272,7 @@ BPF_CALL_1(bpf_get_listener_sock, struct sock *, sk)
 {
 	sk = sk_to_full_sk(sk);
 
-	if (sk->sk_state == TCP_LISTEN && sock_flag(sk, SOCK_RCU_FREE))
+	if (sk && sk->sk_state == TCP_LISTEN && sock_flag(sk, SOCK_RCU_FREE))
 		return (unsigned long)sk;
 
 	return (unsigned long)NULL;