/* * linux/drivers/char/raw.c * * Front-end raw character devices.  These can be bound to any block * devices to provide genuine Unix raw character device semantics. * * We reserve minor number 0 for a control interface.  ioctl()s on this * device are used to bind the other minor numbers to block devices. */ #include <linux/init.h>#include <linux/fs.h>#include <linux/major.h>#include <linux/blkdev.h>#include <linux/module.h>#include <linux/raw.h>#include <linux/capability.h>#include <linux/uio.h>#include <linux/cdev.h>#include <linux/device.h>#include <linux/mutex.h>#include <linux/gfp.h>#include <linux/compat.h>#include <linux/vmalloc.h> #include <asm/uaccess.h> struct raw_device_data {	struct block_device *binding;	int inuse;}; static struct class *raw_class;static struct raw_device_data *raw_devices;static DEFINE_MUTEX(raw_mutex);static const struct file_operations raw_ctl_fops; /* forward declaration */ static int max_raw_minors = MAX_RAW_MINORS; module_param(max_raw_minors, int, 0);MODULE_PARM_DESC(max_raw_minors, "Maximum number of raw devices (1-65536)"); /* * Open/close code for raw IO. * * We just rewrite the i_mapping for the /dev/raw/rawN file descriptor to * point at the blockdev's address_space and set the file handle to use * O_DIRECT. * * Set the device's soft blocksize to the minimum possible.  This gives the * finest possible alignment and has no adverse impact on performance. */static int raw_open(struct inode *inode, struct file *filp){	const int minor = iminor(inode);	struct block_device *bdev;	int err; 	if (minor == 0) {	/* It is the control device */		filp->f_op = &raw_ctl_fops;		return 0;	} 	mutex_lock(&raw_mutex); 	/*	 * All we need to do on open is check that the device is bound.	 */	bdev = raw_devices[minor].binding;	err = -ENODEV;	if (!bdev)		goto out;	igrab(bdev->bd_inode);	err = blkdev_get(bdev, filp->f_mode | FMODE_EXCL, raw_open);	if (err)		goto out;	err = set_blocksize(bdev, bdev_logical_block_size(bdev));	if (err)		goto out1;	filp->f_flags |= O_DIRECT;	filp->f_mapping = bdev->bd_inode->i_mapping;	if (++raw_devices[minor].inuse == 1)		file_inode(filp)->i_mapping =			bdev->bd_inode->i_mapping;	filp->private_data = bdev;	mutex_unlock(&raw_mutex);	return 0; out1:	blkdev_put(bdev, filp->f_mode | FMODE_EXCL);out:	mutex_unlock(&raw_mutex);	return err;} /* * When the final fd which refers to this character-special node is closed, we * make its ->mapping point back at its own i_data. */static int raw_release(struct inode *inode, struct file *filp){	const int minor= iminor(inode);	struct block_device *bdev; 	mutex_lock(&raw_mutex);	bdev = raw_devices[minor].binding;	if (--raw_devices[minor].inuse == 0) {		/* Here  inode->i_mapping == bdev->bd_inode->i_mapping  */		inode->i_mapping = &inode->i_data;		inode->i_mapping->backing_dev_info = &default_backing_dev_info;	}	mutex_unlock(&raw_mutex); 	blkdev_put(bdev, filp->f_mode | FMODE_EXCL);	return 0;} /* * Forward ioctls to the underlying block device. */static longraw_ioctl(struct file *filp, unsigned int command, unsigned long arg){	struct block_device *bdev = filp->private_data;	return blkdev_ioctl(bdev, 0, command, arg);} static int bind_set(int number, u64 major, u64 minor){	dev_t dev = MKDEV(major, minor);	struct raw_device_data *rawdev;	int err = 0; 	if (number <= 0 || number >= max_raw_minors)		return -EINVAL; 	if (MAJOR(dev) != major || MINOR(dev) != minor)		return -EINVAL; 	rawdev = &raw_devices[number]; 	/*	 * This is like making block devices, so demand the	 * same capability	 */	if (!capable(CAP_SYS_ADMIN))		return -EPERM; 	/*	 * For now, we don't need to check that the underlying	 * block device is present or not: we can do that when	 * the raw device is opened.  Just check that the	 * major/minor numbers make sense.	 */ 	if (MAJOR(dev) == 0 && dev != 0)		return -EINVAL; 	mutex_lock(&raw_mutex);	if (rawdev->inuse) {		mutex_unlock(&raw_mutex);		return -EBUSY;	}	if (rawdev->binding) {		bdput(rawdev->binding);		module_put(THIS_MODULE);	}	if (!dev) {		/* unbind */		rawdev->binding = NULL;		device_destroy(raw_class, MKDEV(RAW_MAJOR, number));	} else {		rawdev->binding = bdget(dev);		if (rawdev->binding == NULL) {			err = -ENOMEM;		} else {			dev_t raw = MKDEV(RAW_MAJOR, number);			__module_get(THIS_MODULE);			device_destroy(raw_class, raw);			device_create(raw_class, NULL, raw, NULL,				      "raw%d", number);		}	}	mutex_unlock(&raw_mutex);	return err;} static int bind_get(int number, dev_t *dev){	struct raw_device_data *rawdev;	struct block_device *bdev; 	if (number <= 0 || number >= MAX_RAW_MINORS)		return -EINVAL; 	rawdev = &raw_devices[number]; 	mutex_lock(&raw_mutex);	bdev = rawdev->binding;	*dev = bdev ? bdev->bd_dev : 0;	mutex_unlock(&raw_mutex);	return 0;} /* * Deal with ioctls against the raw-device control interface, to bind * and unbind other raw devices. */static long raw_ctl_ioctl(struct file *filp, unsigned int command,			  unsigned long arg){	struct raw_config_request rq;	dev_t dev;	int err; 	switch (command) {	case RAW_SETBIND:		if (copy_from_user(&rq, (void __user *) arg, sizeof(rq)))			return -EFAULT; 		return bind_set(rq.raw_minor, rq.block_major, rq.block_minor); 	case RAW_GETBIND:		if (copy_from_user(&rq, (void __user *) arg, sizeof(rq)))			return -EFAULT; 		err = bind_get(rq.raw_minor, &dev);		if (err)			return err; 		rq.block_major = MAJOR(dev);		rq.block_minor = MINOR(dev); 		if (copy_to_user((void __user *)arg, &rq, sizeof(rq)))			return -EFAULT; 		return 0;	} 	return -EINVAL;} #ifdef CONFIG_COMPATstruct raw32_config_request {	compat_int_t	raw_minor;	compat_u64	block_major;	compat_u64	block_minor;}; static long raw_ctl_compat_ioctl(struct file *file, unsigned int cmd,				unsigned long arg){	struct raw32_config_request __user *user_req = compat_ptr(arg);	struct raw32_config_request rq;	dev_t dev;	int err = 0; 	switch (cmd) {	case RAW_SETBIND:		if (copy_from_user(&rq, user_req, sizeof(rq)))			return -EFAULT; 		return bind_set(rq.raw_minor, rq.block_major, rq.block_minor); 	case RAW_GETBIND:		if (copy_from_user(&rq, user_req, sizeof(rq)))			return -EFAULT; 		err = bind_get(rq.raw_minor, &dev);		if (err)			return err; 		rq.block_major = MAJOR(dev);		rq.block_minor = MINOR(dev); 		if (copy_to_user(user_req, &rq, sizeof(rq)))			return -EFAULT; 		return 0;	} 	return -EINVAL;}#endif static const struct file_operations raw_fops = {	.read		= do_sync_read,	.aio_read	= generic_file_aio_read,	.write		= do_sync_write,	.aio_write	= blkdev_aio_write,	.fsync		= blkdev_fsync,	.open		= raw_open,	.release	= raw_release,	.unlocked_ioctl = raw_ioctl,	.llseek		= default_llseek,	.owner		= THIS_MODULE,}; static const struct file_operations raw_ctl_fops = {	.unlocked_ioctl = raw_ctl_ioctl,#ifdef CONFIG_COMPAT	.compat_ioctl	= raw_ctl_compat_ioctl,#endif	.open		= raw_open,	.owner		= THIS_MODULE,	.llseek		= noop_llseek,}; static struct cdev raw_cdev; static char *raw_devnode(struct device *dev, umode_t *mode){	return kasprintf(GFP_KERNEL, "raw/%s", dev_name(dev));} static int __init raw_init(void){	dev_t dev = MKDEV(RAW_MAJOR, 0);	int ret; 	if (max_raw_minors < 1 || max_raw_minors > 65536) {		printk(KERN_WARNING "raw: invalid max_raw_minors (must be"			" between 1 and 65536), using %d\n", MAX_RAW_MINORS);		max_raw_minors = MAX_RAW_MINORS;	} 	raw_devices = vzalloc(sizeof(struct raw_device_data) * max_raw_minors);	if (!raw_devices) {		printk(KERN_ERR "Not enough memory for raw device structures\n");		ret = -ENOMEM;		goto error;	} 	ret = register_chrdev_region(dev, max_raw_minors, "raw");	if (ret)		goto error; 	cdev_init(&raw_cdev, &raw_fops);	ret = cdev_add(&raw_cdev, dev, max_raw_minors);	if (ret) {		goto error_region;	} 	raw_class = class_create(THIS_MODULE, "raw");	if (IS_ERR(raw_class)) {		printk(KERN_ERR "Error creating raw class.\n");		cdev_del(&raw_cdev);		ret = PTR_ERR(raw_class);		goto error_region;	}	raw_class->devnode = raw_devnode;	device_create(raw_class, NULL, MKDEV(RAW_MAJOR, 0), NULL, "rawctl"); 	return 0; error_region:	unregister_chrdev_region(dev, max_raw_minors);error:	vfree(raw_devices);	return ret;} static void __exit raw_exit(void){	device_destroy(raw_class, MKDEV(RAW_MAJOR, 0));	class_destroy(raw_class);	cdev_del(&raw_cdev);	unregister_chrdev_region(MKDEV(RAW_MAJOR, 0), max_raw_minors);} module_init(raw_init);module_exit(raw_exit);MODULE_LICENSE("GPL");