mei: add connect with vtag ioctl

This IOCTL is used to associate the current file descriptor
with a FW Client (given by UUID), and virtual tag (vtag).
The IOCTL opens a communication channel between a host client
and a FW client on a tagged channel. From this point on,
every reader and write will communicate with the associated
FW client on the tagged channel. Upon close() the communication
is terminated.

The IOCTL argument is a struct with a union that contains
the input parameter and the output parameter for this IOCTL.

The input parameter is UUID of the FW Client, a vtag [0,255]
The output parameter is the properties of the FW client

Clients that do not support tagged connection
will respond with -EOPNOTSUPP

Signed-off-by: Alexander Usyskin <[e-mail]>
Signed-off-by: Tomas Winkler <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/misc/mei/main.c

···
  * mei_ioctl_connect_client - the connect to fw client IOCTL function
  *
  * @file: private data of the file object
- * @data: IOCTL connect data, input and output parameters
+ * @in_client_uuid: requested UUID for connection
+ * @client: IOCTL connect data, output parameters
  *
  * Locking: called under "dev->device_lock" lock
  *
  * Return: 0 on success, <0 on failure.
  */
 static int mei_ioctl_connect_client(struct file *file,
-			struct mei_connect_client_data *data)
+				    const uuid_le *in_client_uuid,
+				    struct mei_client *client)
 {
 	struct mei_device *dev;
-	struct mei_client *client;
 	struct mei_me_client *me_cl;
 	struct mei_cl *cl;
 	int rets;
···
 	cl = file->private_data;
 	dev = cl->dev;
 
-	if (dev->dev_state != MEI_DEV_ENABLED)
-		return -ENODEV;
-
 	if (cl->state != MEI_FILE_INITIALIZING &&
 	    cl->state != MEI_FILE_DISCONNECTED)
 		return  -EBUSY;
 
 	/* find ME client we're trying to connect to */
-	me_cl = mei_me_cl_by_uuid(dev, &data->in_client_uuid);
+	me_cl = mei_me_cl_by_uuid(dev, in_client_uuid);
 	if (!me_cl) {
 		dev_dbg(dev->dev, "Cannot connect to FW Client UUID = %pUl\n",
-			&data->in_client_uuid);
+			in_client_uuid);
 		rets = -ENOTTY;
 		goto end;
 	}
···
 			 !dev->allow_fixed_address : !dev->hbm_f_fa_supported;
 		if (forbidden) {
 			dev_dbg(dev->dev, "Connection forbidden to FW Client UUID = %pUl\n",
-				&data->in_client_uuid);
+				in_client_uuid);
 			rets = -ENOTTY;
 			goto end;
 		}
···
 			me_cl->props.max_msg_length);
 
 	/* prepare the output buffer */
-	client = &data->out_client_properties;
 	client->max_msg_length = me_cl->props.max_msg_length;
 	client->protocol_version = me_cl->props.protocol_version;
 	dev_dbg(dev->dev, "Can connect?\n");
···
 end:
 	mei_me_cl_put(me_cl);
 	return rets;
+}
+
+/**
+ * mei_vt_support_check - check if client support vtags
+ *
+ * Locking: called under "dev->device_lock" lock
+ *
+ * @dev: mei_device
+ * @uuid: client UUID
+ *
+ * Return:
+ *	0 - supported
+ *	-ENOTTY - no such client
+ *	-EOPNOTSUPP - vtags are not supported by client
+ */
+static int mei_vt_support_check(struct mei_device *dev, const uuid_le *uuid)
+{
+	struct mei_me_client *me_cl;
+	int ret;
+
+	if (!dev->hbm_f_vt_supported)
+		return -EOPNOTSUPP;
+
+	me_cl = mei_me_cl_by_uuid(dev, uuid);
+	if (!me_cl) {
+		dev_dbg(dev->dev, "Cannot connect to FW Client UUID = %pUl\n",
+			uuid);
+		return -ENOTTY;
+	}
+	ret = me_cl->props.vt_supported ? 0 : -EOPNOTSUPP;
+	mei_me_cl_put(me_cl);
+
+	return ret;
+}
+
+/**
+ * mei_ioctl_connect_vtag - connect to fw client with vtag IOCTL function
+ *
+ * @file: private data of the file object
+ * @in_client_uuid: requested UUID for connection
+ * @client: IOCTL connect data, output parameters
+ * @vtag: vm tag
+ *
+ * Locking: called under "dev->device_lock" lock
+ *
+ * Return: 0 on success, <0 on failure.
+ */
+static int mei_ioctl_connect_vtag(struct file *file,
+				  const uuid_le *in_client_uuid,
+				  struct mei_client *client,
+				  u8 vtag)
+{
+	struct mei_device *dev;
+	struct mei_cl *cl;
+	struct mei_cl *pos;
+	struct mei_cl_vtag *cl_vtag;
+
+	cl = file->private_data;
+	dev = cl->dev;
+
+	dev_dbg(dev->dev, "FW Client %pUl vtag %d\n", in_client_uuid, vtag);
+
+	switch (cl->state) {
+	case MEI_FILE_DISCONNECTED:
+		if (mei_cl_vtag_by_fp(cl, file) != vtag) {
+			dev_err(dev->dev, "reconnect with different vtag\n");
+			return -EINVAL;
+		}
+		break;
+	case MEI_FILE_INITIALIZING:
+		/* malicious connect from another thread may push vtag */
+		if (!IS_ERR(mei_cl_fp_by_vtag(cl, vtag))) {
+			dev_err(dev->dev, "vtag already filled\n");
+			return -EINVAL;
+		}
+
+		list_for_each_entry(pos, &dev->file_list, link) {
+			if (pos == cl)
+				continue;
+			if (!pos->me_cl)
+				continue;
+
+			/* only search for same UUID */
+			if (uuid_le_cmp(*mei_cl_uuid(pos), *in_client_uuid))
+				continue;
+
+			/* if tag already exist try another fp */
+			if (!IS_ERR(mei_cl_fp_by_vtag(pos, vtag)))
+				continue;
+
+			/* replace cl with acquired one */
+			dev_dbg(dev->dev, "replacing with existing cl\n");
+			mei_cl_unlink(cl);
+			kfree(cl);
+			file->private_data = pos;
+			cl = pos;
+			break;
+		}
+
+		cl_vtag = mei_cl_vtag_alloc(file, vtag);
+		if (IS_ERR(cl_vtag))
+			return -ENOMEM;
+
+		list_add_tail(&cl_vtag->list, &cl->vtag_map);
+		break;
+	default:
+		return -EBUSY;
+	}
+
+	while (cl->state != MEI_FILE_INITIALIZING &&
+	       cl->state != MEI_FILE_DISCONNECTED &&
+	       cl->state != MEI_FILE_CONNECTED) {
+		mutex_unlock(&dev->device_lock);
+		wait_event_timeout(cl->wait,
+				   (cl->state == MEI_FILE_CONNECTED ||
+				    cl->state == MEI_FILE_DISCONNECTED ||
+				    cl->state == MEI_FILE_DISCONNECT_REQUIRED ||
+				    cl->state == MEI_FILE_DISCONNECT_REPLY),
+				   mei_secs_to_jiffies(MEI_CL_CONNECT_TIMEOUT));
+		mutex_lock(&dev->device_lock);
+	}
+
+	if (!mei_cl_is_connected(cl))
+		return mei_ioctl_connect_client(file, in_client_uuid, client);
+
+	client->max_msg_length = cl->me_cl->props.max_msg_length;
+	client->protocol_version = cl->me_cl->props.protocol_version;
+
+	return 0;
 }
 
 /**
···
 {
 	struct mei_device *dev;
 	struct mei_cl *cl = file->private_data;
-	struct mei_connect_client_data connect_data;
+	struct mei_connect_client_data conn;
+	struct mei_connect_client_data_vtag conn_vtag;
+	const uuid_le *cl_uuid;
+	struct mei_client *props;
+	u8 vtag;
 	u32 notify_get, notify_req;
 	int rets;
 
···
 	switch (cmd) {
 	case IOCTL_MEI_CONNECT_CLIENT:
 		dev_dbg(dev->dev, ": IOCTL_MEI_CONNECT_CLIENT.\n");
-		if (copy_from_user(&connect_data, (char __user *)data,
-				   sizeof(connect_data))) {
+		if (copy_from_user(&conn, (char __user *)data, sizeof(conn))) {
+			dev_dbg(dev->dev, "failed to copy data from userland\n");
+			rets = -EFAULT;
+			goto out;
+		}
+		cl_uuid = &conn.in_client_uuid;
+		props = &conn.out_client_properties;
+		vtag = 0;
+
+		rets = mei_vt_support_check(dev, cl_uuid);
+		if (rets == -ENOTTY)
+			goto out;
+		if (!rets)
+			rets = mei_ioctl_connect_vtag(file, cl_uuid, props,
+						      vtag);
+		else
+			rets = mei_ioctl_connect_client(file, cl_uuid, props);
+		if (rets)
+			goto out;
+
+		/* if all is ok, copying the data back to user. */
+		if (copy_to_user((char __user *)data, &conn, sizeof(conn))) {
+			dev_dbg(dev->dev, "failed to copy data to userland\n");
+			rets = -EFAULT;
+			goto out;
+		}
+
+		break;
+
+	case IOCTL_MEI_CONNECT_CLIENT_VTAG:
+		dev_dbg(dev->dev, "IOCTL_MEI_CONNECT_CLIENT_VTAG\n");
+		if (copy_from_user(&conn_vtag, (char __user *)data,
+				   sizeof(conn_vtag))) {
 			dev_dbg(dev->dev, "failed to copy data from userland\n");
 			rets = -EFAULT;
 			goto out;
 		}
 
-		rets = mei_ioctl_connect_client(file, &connect_data);
+		cl_uuid = &conn_vtag.connect.in_client_uuid;
+		props = &conn_vtag.out_client_properties;
+		vtag = conn_vtag.connect.vtag;
+
+		rets = mei_vt_support_check(dev, cl_uuid);
+		if (rets == -EOPNOTSUPP)
+			dev_dbg(dev->dev, "FW Client %pUl does not support vtags\n",
+				cl_uuid);
+		if (rets)
+			goto out;
+
+		if (!vtag) {
+			dev_dbg(dev->dev, "vtag can't be zero\n");
+			rets = -EINVAL;
+			goto out;
+		}
+
+		rets = mei_ioctl_connect_vtag(file, cl_uuid, props, vtag);
 		if (rets)
 			goto out;
 
 		/* if all is ok, copying the data back to user. */
-		if (copy_to_user((char __user *)data, &connect_data,
-				 sizeof(connect_data))) {
+		if (copy_to_user((char __user *)data, &conn_vtag,
+				 sizeof(conn_vtag))) {
 			dev_dbg(dev->dev, "failed to copy data to userland\n");
 			rets = -EFAULT;
 			goto out;

include/uapi/linux/mei.h

···
  */
 #define IOCTL_MEI_NOTIFY_GET _IOR('H', 0x03, __u32)
 
+/**
+ * struct mei_connect_client_vtag - mei client information struct with vtag
+ *
+ * @in_client_uuid: UUID of client to connect
+ * @vtag: virtual tag
+ * @reserved: reserved for future use
+ */
+struct mei_connect_client_vtag {
+	uuid_le in_client_uuid;
+	__u8 vtag;
+	__u8 reserved[3];
+};
+
+/**
+ * struct mei_connect_client_data_vtag - IOCTL connect data union
+ *
+ * @connect: input connect data
+ * @out_client_properties: output client data
+ */
+struct mei_connect_client_data_vtag {
+	union {
+		struct mei_connect_client_vtag connect;
+		struct mei_client out_client_properties;
+	};
+};
+
+/**
+ * DOC:
+ * This IOCTL is used to associate the current file descriptor with a
+ * FW Client (given by UUID), and virtual tag (vtag).
+ * The IOCTL opens a communication channel between a host client and
+ * a FW client on a tagged channel. From this point on, every read
+ * and write will communicate with the associated FW client with
+ * on the tagged channel.
+ * Upone close() the communication is terminated.
+ *
+ * The IOCTL argument is a struct with a union that contains
+ * the input parameter and the output parameter for this IOCTL.
+ *
+ * The input parameter is UUID of the FW Client, a vtag [0,255]
+ * The output parameter is the properties of the FW client
+ * (FW protocool version and max message size).
+ *
+ * Clients that do not support tagged connection
+ * will respond with -EOPNOTSUPP.
+ */
+#define IOCTL_MEI_CONNECT_CLIENT_VTAG \
+	_IOWR('H', 0x04, struct mei_connect_client_data_vtag)
+
 #endif /* _LINUX_MEI_H  */