Merge: bpf, vsock: Invoke proto::close on close()

MR: https://gitlab.com/redhat/centos-stream/src/kernel/centos-stream-9/-/merge_requests/6745

JIRA: https://issues.redhat.com/browse/RHEL-81484
CVE: CVE-2025-21756
Upstream: Merged

bpf, vsock: Invoke proto::close on close()
vsock: Keep the binding until socket destruction
https://gitlab.com/redhat/centos-stream/src/kernel/centos-stream-9/-/merge_requests/6745

Fixes: c0cfa2d ("vsock: add multi-transports support")
Fixes: 634f1a7 ("vsock: support sockmap")
Fixes: fcdd224 ("vsock: Keep the binding until socket destruction")

Signed-off-by: Jon Maloy <jmaloy@redhat.com>

Approved-by: Stefano Garzarella <sgarzare@redhat.com>
Approved-by: Luigi Leonardi <leonardi@redhat.com>
Approved-by: Jay Shin <jaeshin@redhat.com>
Approved-by: CKI KWF Bot <cki-ci-bot+kwf-gitlab-com@redhat.com>

Merged-by: Augusto Caringi <acaringi@redhat.com>

Author: caringi

net/vmw_vsock/af_vsock.c

@@ -116,12 +116,14 @@
 static int __vsock_bind(struct sock *sk, struct sockaddr_vm *addr);
 static void vsock_sk_destruct(struct sock *sk);
 static int vsock_queue_rcv_skb(struct sock *sk, struct sk_buff *skb);
+static void vsock_close(struct sock *sk, long timeout);
 
 /* Protocol family. */
 struct proto vsock_proto = {
 	.name = "AF_VSOCK",
 	.owner = THIS_MODULE,
 	.obj_size = sizeof(struct vsock_sock),
+	.close = vsock_close,
 #ifdef CONFIG_BPF_SYSCALL
 	.psock_update_sk_prot = vsock_bpf_update_proto,
 #endif
@@ -334,7 +336,10 @@ EXPORT_SYMBOL_GPL(vsock_find_connected_socket);
 
 void vsock_remove_sock(struct vsock_sock *vsk)
 {
-	vsock_remove_bound(vsk);
+	/* Transport reassignment must not remove the binding. */
+	if (sock_flag(sk_vsock(vsk), SOCK_DEAD))
+		vsock_remove_bound(vsk);
+
 	vsock_remove_connected(vsk);
 }
 EXPORT_SYMBOL_GPL(vsock_remove_sock);
@@ -797,39 +802,44 @@ static bool sock_type_connectible(u16 type)
 
 static void __vsock_release(struct sock *sk, int level)
 {
-	if (sk) {
-		struct sock *pending;
-		struct vsock_sock *vsk;
+	struct vsock_sock *vsk;
+	struct sock *pending;
 
-		vsk = vsock_sk(sk);
-		pending = NULL;	/* Compiler warning. */
+	vsk = vsock_sk(sk);
+	pending = NULL;	/* Compiler warning. */
 
-		/* When "level" is SINGLE_DEPTH_NESTING, use the nested
-		 * version to avoid the warning "possible recursive locking
-		 * detected". When "level" is 0, lock_sock_nested(sk, level)
-		 * is the same as lock_sock(sk).
-		 */
-		lock_sock_nested(sk, level);
+	/* When "level" is SINGLE_DEPTH_NESTING, use the nested
+	 * version to avoid the warning "possible recursive locking
+	 * detected". When "level" is 0, lock_sock_nested(sk, level)
+	 * is the same as lock_sock(sk).
+	 */
+	lock_sock_nested(sk, level);
 
-		if (vsk->transport)
-			vsk->transport->release(vsk);
-		else if (sock_type_connectible(sk->sk_type))
-			vsock_remove_sock(vsk);
+	/* Indicate to vsock_remove_sock() that the socket is being released and
+	 * can be removed from the bound_table. Unlike transport reassignment
+	 * case, where the socket must remain bound despite vsock_remove_sock()
+	 * being called from the transport release() callback.
+	 */
+	sock_set_flag(sk, SOCK_DEAD);
 
-		sock_orphan(sk);
-		sk->sk_shutdown = SHUTDOWN_MASK;
+	if (vsk->transport)
+		vsk->transport->release(vsk);
+	else if (sock_type_connectible(sk->sk_type))
+		vsock_remove_sock(vsk);
 
-		skb_queue_purge(&sk->sk_receive_queue);
+	sock_orphan(sk);
+	sk->sk_shutdown = SHUTDOWN_MASK;
 
-		/* Clean up any sockets that never were accepted. */
-		while ((pending = vsock_dequeue_accept(sk)) != NULL) {
-			__vsock_release(pending, SINGLE_DEPTH_NESTING);
-			sock_put(pending);
-		}
+	skb_queue_purge(&sk->sk_receive_queue);
 
-		release_sock(sk);
-		sock_put(sk);
+	/* Clean up any sockets that never were accepted. */
+	while ((pending = vsock_dequeue_accept(sk)) != NULL) {
+		__vsock_release(pending, SINGLE_DEPTH_NESTING);
+		sock_put(pending);
 	}
+
+	release_sock(sk);
+	sock_put(sk);
 }
 
 static void vsock_sk_destruct(struct sock *sk)
@@ -910,9 +920,22 @@ void vsock_data_ready(struct sock *sk)
 }
 EXPORT_SYMBOL_GPL(vsock_data_ready);
 
+/* Dummy callback required by sockmap.
+ * See unconditional call of saved_close() in sock_map_close().
+ */
+static void vsock_close(struct sock *sk, long timeout)
+{
+}
+
 static int vsock_release(struct socket *sock)
 {
-	__vsock_release(sock->sk, 0);
+	struct sock *sk = sock->sk;
+
+	if (!sk)
+		return 0;
+
+	sk->sk_prot->close(sk, 0);
+	__vsock_release(sk, 0);
 	sock->sk = NULL;
 	sock->state = SS_FREE;