ksmbd: check outstanding simultaneous SMB operations

Signed-off-by: Namjae Jeon <[email protected]>

connection.c

@@ -77,6 +77,7 @@ struct ksmbd_conn *ksmbd_conn_alloc(void)
 	atomic_set(&conn->req_running, 0);
 	atomic_set(&conn->r_count, 0);
 	atomic_set(&conn->refcnt, 1);
+	atomic_set(&conn->mux_smb_requests, 0);
 	conn->total_credits = 1;
 	conn->outstanding_credits = 0;
 

connection.h

@@ -107,6 +107,7 @@ struct ksmbd_conn {
 	__le16				signing_algorithm;
 	bool				binding;
 	atomic_t			refcnt;
+	atomic_t			mux_smb_requests;
 };
 
 struct ksmbd_conn_ops {

server.c

@@ -270,6 +270,7 @@ static void handle_ksmbd_work(struct work_struct *wk)
 
 	ksmbd_conn_try_dequeue_request(work);
 	ksmbd_free_work_struct(work);
+	atomic_dec(&conn->mux_smb_requests);
 	/*
 	 * Checking waitqueue to dropping pending requests on
 	 * disconnection. waitqueue_active is safe because it
@@ -291,6 +292,15 @@ static int queue_ksmbd_work(struct ksmbd_conn *conn)
 	struct ksmbd_work *work;
 	int err;
 
+	err = ksmbd_init_smb_server(conn);
+	if (err)
+		return 0;
+
+	if (atomic_inc_return(&conn->mux_smb_requests) >= conn->vals->max_credits) {
+		atomic_dec_return(&conn->mux_smb_requests);
+		return ENOSPC;
+	}
+
 	work = ksmbd_alloc_work_struct();
 	if (!work) {
 		pr_err("allocation for work failed\n");
@@ -301,12 +311,6 @@ static int queue_ksmbd_work(struct ksmbd_conn *conn)
 	work->request_buf = conn->request_buf;
 	conn->request_buf = NULL;
 
-	err = ksmbd_init_smb_server(work);
-	if (err) {
-		ksmbd_free_work_struct(work);
-		return 0;
-	}
-
 	ksmbd_conn_enqueue_request(work);
 	atomic_inc(&conn->r_count);
 	/* update activity on connection */

smb1ops.c

@@ -31,6 +31,7 @@ static struct smb_version_values smb1_server_values = {
 	.cap_large_files = CAP_LARGE_FILES,
 	.signing_enabled = SECMODE_SIGN_ENABLED,
 	.signing_required = SECMODE_SIGN_REQUIRED,
+	.max_credits = SMB2_MAX_CREDITS,
 };
 
 static struct smb_version_ops smb1_server_ops = {

smb_common.c

@@ -425,6 +425,10 @@ static struct smb_version_ops smb1_server_ops = {
 	.set_rsp_status = set_smb1_rsp_status,
 };
 
+static struct smb_version_values smb1_server_values = {
+	.max_credits = SMB2_MAX_CREDITS,
+};
+
 static int smb1_negotiate(struct ksmbd_work *work)
 {
 	return ksmbd_smb_negotiate_common(work, SMB_COM_NEGOTIATE);
@@ -436,19 +440,19 @@ static struct smb_version_cmds smb1_server_cmds[1] = {
 
 static int init_smb1_server(struct ksmbd_conn *conn)
 {
+	conn->vals = &smb1_server_values;
 	conn->ops = &smb1_server_ops;
 	conn->cmds = smb1_server_cmds;
 	conn->max_cmds = ARRAY_SIZE(smb1_server_cmds);
 	return 0;
 }
 #endif
 
-int ksmbd_init_smb_server(struct ksmbd_work *work)
+int ksmbd_init_smb_server(struct ksmbd_conn *conn)
 {
-	struct ksmbd_conn *conn = work->conn;
 	__le32 proto;
 
-	proto = *(__le32 *)((struct smb_hdr *)work->request_buf)->Protocol;
+	proto = *(__le32 *)((struct smb_hdr *)conn->request_buf)->Protocol;
 	if (conn->need_neg == false) {
 		if (proto == SMB1_PROTO_NUMBER)
 			return -EINVAL;

smb_common.h

@@ -512,7 +512,7 @@ bool ksmbd_smb_request(struct ksmbd_conn *conn);
 
 int ksmbd_lookup_dialect_by_id(__le16 *cli_dialects, __le16 dialects_count);
 
-int ksmbd_init_smb_server(struct ksmbd_work *work);
+int ksmbd_init_smb_server(struct ksmbd_conn *conn);
 
 bool ksmbd_pdu_size_has_room(unsigned int pdu);