Merge branch 'af_unix-fix-bunch-of-msg_oob-bugs-and-add-new-tests'

Kuniyuki Iwashima says:

====================
af_unix: Fix bunch of MSG_OOB bugs and add new tests.

This series rewrites the selftest for AF_UNIX MSG_OOB and fixes
bunch of bugs that AF_UNIX behaves differently compared to TCP.

Note that the test discovered few more bugs in TCP side, which
will be fixed in another series.
====================

Link: https://lore.kernel.org/r/20240625013645.45034-1-kuniyu@amazon.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

Author: Paolo Abeni

net/unix/af_unix.c

@@ -2613,10 +2613,24 @@ static struct sk_buff *manage_oob(struct sk_buff *skb, struct sock *sk,
 {
 	struct unix_sock *u = unix_sk(sk);
 
-	if (!unix_skb_len(skb) && !(flags & MSG_PEEK)) {
-		skb_unlink(skb, &sk->sk_receive_queue);
-		consume_skb(skb);
-		skb = NULL;
+	if (!unix_skb_len(skb)) {
+		struct sk_buff *unlinked_skb = NULL;
+
+		spin_lock(&sk->sk_receive_queue.lock);
+
+		if (copied && (!u->oob_skb || skb == u->oob_skb)) {
+			skb = NULL;
+		} else if (flags & MSG_PEEK) {
+			skb = skb_peek_next(skb, &sk->sk_receive_queue);
+		} else {
+			unlinked_skb = skb;
+			skb = skb_peek_next(skb, &sk->sk_receive_queue);
+			__skb_unlink(unlinked_skb, &sk->sk_receive_queue);
+		}
+
+		spin_unlock(&sk->sk_receive_queue.lock);
+
+		consume_skb(unlinked_skb);
 	} else {
 		struct sk_buff *unlinked_skb = NULL;
 
@@ -3093,12 +3107,23 @@ static int unix_ioctl(struct socket *sock, unsigned int cmd, unsigned long arg)
 #if IS_ENABLED(CONFIG_AF_UNIX_OOB)
 	case SIOCATMARK:
 		{
+			struct unix_sock *u = unix_sk(sk);
 			struct sk_buff *skb;
 			int answ = 0;
 
+			mutex_lock(&u->iolock);
+
 			skb = skb_peek(&sk->sk_receive_queue);
-			if (skb && skb == READ_ONCE(unix_sk(sk)->oob_skb))
-				answ = 1;
+			if (skb) {
+				struct sk_buff *oob_skb = READ_ONCE(u->oob_skb);
+
+				if (skb == oob_skb ||
+				    (!oob_skb && !unix_skb_len(skb)))
+					answ = 1;
+			}
+
+			mutex_unlock(&u->iolock);
+
 			err = put_user(answ, (int __user *)arg);
 		}
 		break;

tools/testing/selftests/net/.gitignore

@@ -43,7 +43,6 @@ tap
 tcp_fastopen_backup_key
 tcp_inq
 tcp_mmap
-test_unix_oob
 timestamping
 tls
 toeplitz

tools/testing/selftests/net/af_unix/Makefile

@@ -1,4 +1,4 @@
 CFLAGS += $(KHDR_INCLUDES)
-TEST_GEN_PROGS := diag_uid test_unix_oob unix_connect scm_pidfd scm_rights
+TEST_GEN_PROGS := diag_uid msg_oob scm_pidfd scm_rights unix_connect
 
 include ../../lib.mk