[PATCH] ksmbd: disconnect on SMB3 decryption failure

[Namjae Jeon <linkinjeon@kernel.org>]

MS-SMB2 requires the server to disconnect a connection when an
encrypted transform cannot be associated with a session or fails
authenticated decryption. This includes an encrypted request that
still carries a SessionId invalidated through PreviousSessionId.

Move the connection to EXITING and shut down its transport when
decrypt_req() fails. Add the missing TCP shutdown callback so a receive
blocked in kernel_recvmsg() is released; SMB Direct already provides
the corresponding callback.

Plaintext requests using an invalidated SessionId do not take this
path and continue to receive STATUS_USER_SESSION_DELETED.

Fixes: e2f34481b24d ("cifsd: add server-side procedures for SMB3")
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
---
 fs/smb/server/connection.c    | 16 ++++++++++++++++
 fs/smb/server/connection.h    |  1 +
 fs/smb/server/server.c        |  4 +++-
 fs/smb/server/transport_tcp.c |  6 ++++++
 4 files changed, 26 insertions(+), 1 deletion(-)

diff --git a/fs/smb/server/connection.c b/fs/smb/server/connection.c
index 71d55d903f6f..5d729473dd18 100644
--- a/fs/smb/server/connection.c
+++ b/fs/smb/server/connection.c
@@ -439,6 +439,22 @@ void ksmbd_all_conn_set_status(struct ksmbd_session *sess, u32 status)
 	up_read(&conn_list_lock);
 }
 
+void ksmbd_conn_abort(struct ksmbd_conn *conn)
+{
+	bool shutdown = false;
+
+	spin_lock(&conn->request_lock);
+	if (!ksmbd_conn_exiting(conn) && !ksmbd_conn_releasing(conn)) {
+		ksmbd_conn_set_exiting(conn);
+		shutdown = true;
+	}
+	spin_unlock(&conn->request_lock);
+	wake_up_all(&conn->req_running_q);
+
+	if (shutdown && conn->transport->ops->shutdown)
+		conn->transport->ops->shutdown(conn->transport);
+}
+
 void ksmbd_conn_wait_idle(struct ksmbd_conn *conn)
 {
 	wait_event(conn->req_running_q, atomic_read(&conn->req_running) < 2);
diff --git a/fs/smb/server/connection.h b/fs/smb/server/connection.h
index c01ccbe8b97c..421907aed473 100644
--- a/fs/smb/server/connection.h
+++ b/fs/smb/server/connection.h
@@ -203,6 +203,7 @@ struct ksmbd_conn *ksmbd_conn_alloc(void);
 void ksmbd_conn_free(struct ksmbd_conn *conn);
 struct ksmbd_conn *ksmbd_conn_get(struct ksmbd_conn *conn);
 void ksmbd_conn_put(struct ksmbd_conn *conn);
+void ksmbd_conn_abort(struct ksmbd_conn *conn);
 int ksmbd_conn_wq_init(void);
 void ksmbd_conn_wq_destroy(void);
 bool ksmbd_conn_lookup_dialect(struct ksmbd_conn *c);
diff --git a/fs/smb/server/server.c b/fs/smb/server/server.c
index 7881fc7bb8cd..ba44bea9ddc3 100644
--- a/fs/smb/server/server.c
+++ b/fs/smb/server/server.c
@@ -188,8 +188,10 @@ static void __handle_ksmbd_work(struct ksmbd_work *work,
 	if (conn->ops->is_transform_hdr &&
 	    conn->ops->is_transform_hdr(work->request_buf)) {
 		rc = conn->ops->decrypt_req(work);
-		if (rc < 0)
+		if (rc < 0) {
+			ksmbd_conn_abort(conn);
 			return;
+		}
 		work->encrypted = true;
 	}
 
diff --git a/fs/smb/server/transport_tcp.c b/fs/smb/server/transport_tcp.c
index 1045eca581c3..0ae5f145a332 100644
--- a/fs/smb/server/transport_tcp.c
+++ b/fs/smb/server/transport_tcp.c
@@ -435,6 +435,11 @@ static void ksmbd_tcp_disconnect(struct ksmbd_transport *t)
 		atomic_dec(&active_num_conn);
 }
 
+static void ksmbd_tcp_shutdown(struct ksmbd_transport *t)
+{
+	kernel_sock_shutdown(TCP_TRANS(t)->sock, SHUT_RDWR);
+}
+
 static void tcp_destroy_socket(struct socket *ksmbd_socket)
 {
 	int ret;
@@ -681,5 +686,6 @@ static const struct ksmbd_transport_ops ksmbd_tcp_transport_ops = {
 	.read		= ksmbd_tcp_read,
 	.writev		= ksmbd_tcp_writev,
 	.disconnect	= ksmbd_tcp_disconnect,
+	.shutdown	= ksmbd_tcp_shutdown,
 	.free_transport = ksmbd_tcp_free_transport,
 };
-- 
2.25.1