[linux.git] / drivers / char / raw.c

/*
 * 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 <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[MAX_RAW_MINORS];
static DEFINE_MUTEX(raw_mutex);
static const struct file_operations raw_ctl_fops; /* forward declaration */

/*
 * 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, 0);
	if (err)
		goto out;
	err = bd_claim(bdev, raw_open);
	if (err)
		goto out1;
	err = set_blocksize(bdev, bdev_hardsect_size(bdev));
	if (err)
		goto out2;
	filp->f_flags |= O_DIRECT;
	filp->f_mapping = bdev->bd_inode->i_mapping;
	if (++raw_devices[minor].inuse == 1)
		filp->f_path.dentry->d_inode->i_mapping =
			bdev->bd_inode->i_mapping;
	filp->private_data = bdev;
	mutex_unlock(&raw_mutex);
	return 0;

out2:
	bd_release(bdev);
out1:
	blkdev_put(bdev);
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);

	bd_release(bdev);
	blkdev_put(bdev);
	return 0;
}

/*
 * Forward ioctls to the underlying block device.
 */
static int
raw_ioctl(struct inode *inode, struct file *filp,
		  unsigned int command, unsigned long arg)
{
	struct block_device *bdev = filp->private_data;

	return blkdev_ioctl(bdev->bd_inode, NULL, command, arg);
}

static void bind_device(struct raw_config_request *rq)
{
	device_destroy(raw_class, MKDEV(RAW_MAJOR, rq->raw_minor));
	device_create(raw_class, NULL, MKDEV(RAW_MAJOR, rq->raw_minor),
		      "raw%d", rq->raw_minor);
}

/*
 * Deal with ioctls against the raw-device control interface, to bind
 * and unbind other raw devices.
 */
static int raw_ctl_ioctl(struct inode *inode, struct file *filp,
			unsigned int command, unsigned long arg)
{
	struct raw_config_request rq;
	struct raw_device_data *rawdev;
	int err = 0;

	switch (command) {
	case RAW_SETBIND:
	case RAW_GETBIND:

		/* First, find out which raw minor we want */

		if (copy_from_user(&rq, (void __user *) arg, sizeof(rq))) {
			err = -EFAULT;
			goto out;
		}

		if (rq.raw_minor <= 0 || rq.raw_minor >= MAX_RAW_MINORS) {
			err = -EINVAL;
			goto out;
		}
		rawdev = &raw_devices[rq.raw_minor];

		if (command == RAW_SETBIND) {
			dev_t dev;

			/*
			 * This is like making block devices, so demand the
			 * same capability
			 */
			if (!capable(CAP_SYS_ADMIN)) {
				err = -EPERM;
				goto out;
			}

			/*
			 * 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.
			 */

			dev = MKDEV(rq.block_major, rq.block_minor);
			if ((rq.block_major == 0 && rq.block_minor != 0) ||
					MAJOR(dev) != rq.block_major ||
					MINOR(dev) != rq.block_minor) {
				err = -EINVAL;
				goto out;
			}

			mutex_lock(&raw_mutex);
			if (rawdev->inuse) {
				mutex_unlock(&raw_mutex);
				err = -EBUSY;
				goto out;
			}
			if (rawdev->binding) {
				bdput(rawdev->binding);
				module_put(THIS_MODULE);
			}
			if (rq.block_major == 0 && rq.block_minor == 0) {
				/* unbind */
				rawdev->binding = NULL;
				device_destroy(raw_class,
						MKDEV(RAW_MAJOR, rq.raw_minor));
			} else {
				rawdev->binding = bdget(dev);
				if (rawdev->binding == NULL)
					err = -ENOMEM;
				else {
					__module_get(THIS_MODULE);
					bind_device(&rq);
				}
			}
			mutex_unlock(&raw_mutex);
		} else {
			struct block_device *bdev;

			mutex_lock(&raw_mutex);
			bdev = rawdev->binding;
			if (bdev) {
				rq.block_major = MAJOR(bdev->bd_dev);
				rq.block_minor = MINOR(bdev->bd_dev);
			} else {
				rq.block_major = rq.block_minor = 0;
			}
			mutex_unlock(&raw_mutex);
			if (copy_to_user((void __user *)arg, &rq, sizeof(rq))) {
				err = -EFAULT;
				goto out;
			}
		}
		break;
	default:
		err = -EINVAL;
		break;
	}
out:
	return err;
}

static const struct file_operations raw_fops = {
	.read	=	do_sync_read,
	.aio_read = 	generic_file_aio_read,
	.write	=	do_sync_write,
	.aio_write = 	generic_file_aio_write_nolock,
	.open	=	raw_open,
	.release=	raw_release,
	.ioctl	=	raw_ioctl,
	.owner	=	THIS_MODULE,
};

static const struct file_operations raw_ctl_fops = {
	.ioctl	=	raw_ctl_ioctl,
	.open	=	raw_open,
	.owner	=	THIS_MODULE,
};

static struct cdev raw_cdev;

static int __init raw_init(void)
{
	dev_t dev = MKDEV(RAW_MAJOR, 0);
	int ret;

	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) {
		kobject_put(&raw_cdev.kobj);
		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;
	}
	device_create(raw_class, NULL, MKDEV(RAW_MAJOR, 0), "rawctl");

	return 0;

error_region:
	unregister_chrdev_region(dev, MAX_RAW_MINORS);
error:
	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");
Commit	Line	Data
1da177e4 LT	1	/*
	2	* linux/drivers/char/raw.c
	3	*
	4	* Front-end raw character devices. These can be bound to any block
	5	* devices to provide genuine Unix raw character device semantics.
	6	*
	7	* We reserve minor number 0 for a control interface. ioctl()s on this
	8	* device are used to bind the other minor numbers to block devices.
	9	*/
	10
	11	#include <linux/init.h>
	12	#include <linux/fs.h>
1da177e4 LT	13	#include <linux/major.h>
	14	#include <linux/blkdev.h>
	15	#include <linux/module.h>
	16	#include <linux/raw.h>
	17	#include <linux/capability.h>
	18	#include <linux/uio.h>
	19	#include <linux/cdev.h>
	20	#include <linux/device.h>
8ed965d6	21	#include <linux/mutex.h>
1da177e4 LT	22
	23	#include <asm/uaccess.h>
	24
	25	struct raw_device_data {
	26	struct block_device *binding;
	27	int inuse;
	28	};
	29
ca8eca68	30	static struct class *raw_class;
1da177e4	31	static struct raw_device_data raw_devices[MAX_RAW_MINORS];
8ed965d6	32	static DEFINE_MUTEX(raw_mutex);
62322d25	33	static const struct file_operations raw_ctl_fops; /* forward declaration */
1da177e4 LT	34
	35	/*
	36	* Open/close code for raw IO.
	37	*
	38	* We just rewrite the i_mapping for the /dev/raw/rawN file descriptor to
	39	* point at the blockdev's address_space and set the file handle to use
	40	* O_DIRECT.
	41	*
	42	* Set the device's soft blocksize to the minimum possible. This gives the
	43	* finest possible alignment and has no adverse impact on performance.
	44	*/
	45	static int raw_open(struct inode inode, struct file filp)
	46	{
	47	const int minor = iminor(inode);
	48	struct block_device *bdev;
	49	int err;
	50
	51	if (minor == 0) { /* It is the control device */
	52	filp->f_op = &raw_ctl_fops;
	53	return 0;
	54	}
	55
8ed965d6	56	mutex_lock(&raw_mutex);
1da177e4 LT	57
	58	/*
	59	* All we need to do on open is check that the device is bound.
	60	*/
	61	bdev = raw_devices[minor].binding;
	62	err = -ENODEV;
	63	if (!bdev)
	64	goto out;
	65	igrab(bdev->bd_inode);
	66	err = blkdev_get(bdev, filp->f_mode, 0);
	67	if (err)
	68	goto out;
	69	err = bd_claim(bdev, raw_open);
	70	if (err)
	71	goto out1;
	72	err = set_blocksize(bdev, bdev_hardsect_size(bdev));
	73	if (err)
	74	goto out2;
	75	filp->f_flags \|= O_DIRECT;
	76	filp->f_mapping = bdev->bd_inode->i_mapping;
	77	if (++raw_devices[minor].inuse == 1)
a7113a96	78	filp->f_path.dentry->d_inode->i_mapping =
1da177e4 LT	79	bdev->bd_inode->i_mapping;
1da177e4 LT	80	filp->private_data = bdev;
8ed965d6	81	mutex_unlock(&raw_mutex);
1da177e4 LT	82	return 0;
	83
	84	out2:
	85	bd_release(bdev);
	86	out1:
	87	blkdev_put(bdev);
	88	out:
8ed965d6	89	mutex_unlock(&raw_mutex);
1da177e4 LT	90	return err;
	91	}
	92
	93	/*
	94	* When the final fd which refers to this character-special node is closed, we
	95	* make its ->mapping point back at its own i_data.
	96	*/
	97	static int raw_release(struct inode inode, struct file filp)
	98	{
	99	const int minor= iminor(inode);
	100	struct block_device *bdev;
	101
8ed965d6	102	mutex_lock(&raw_mutex);
1da177e4 LT	103	bdev = raw_devices[minor].binding;
	104	if (--raw_devices[minor].inuse == 0) {
	105	/* Here inode->i_mapping == bdev->bd_inode->i_mapping */
	106	inode->i_mapping = &inode->i_data;
	107	inode->i_mapping->backing_dev_info = &default_backing_dev_info;
	108	}
8ed965d6	109	mutex_unlock(&raw_mutex);
1da177e4 LT	110
	111	bd_release(bdev);
	112	blkdev_put(bdev);
	113	return 0;
	114	}
	115
	116	/*
	117	* Forward ioctls to the underlying block device.
	118	*/
	119	static int
	120	raw_ioctl(struct inode inode, struct file filp,
	121	unsigned int command, unsigned long arg)
	122	{
	123	struct block_device *bdev = filp->private_data;
	124
e72022e1	125	return blkdev_ioctl(bdev->bd_inode, NULL, command, arg);
1da177e4 LT	126	}
	127
	128	static void bind_device(struct raw_config_request *rq)
	129	{
38ca6c34 GKH	130	device_destroy(raw_class, MKDEV(RAW_MAJOR, rq->raw_minor));
	131	device_create(raw_class, NULL, MKDEV(RAW_MAJOR, rq->raw_minor),
	132	"raw%d", rq->raw_minor);
1da177e4 LT	133	}
	134
	135	/*
	136	* Deal with ioctls against the raw-device control interface, to bind
	137	* and unbind other raw devices.
	138	*/
	139	static int raw_ctl_ioctl(struct inode inode, struct file filp,
	140	unsigned int command, unsigned long arg)
	141	{
	142	struct raw_config_request rq;
	143	struct raw_device_data *rawdev;
	144	int err = 0;
	145
	146	switch (command) {
	147	case RAW_SETBIND:
	148	case RAW_GETBIND:
	149
	150	/* First, find out which raw minor we want */
	151
	152	if (copy_from_user(&rq, (void __user *) arg, sizeof(rq))) {
	153	err = -EFAULT;
	154	goto out;
	155	}
	156
38584c14	157	if (rq.raw_minor <= 0 \|\| rq.raw_minor >= MAX_RAW_MINORS) {
1da177e4 LT	158	err = -EINVAL;
	159	goto out;
	160	}
	161	rawdev = &raw_devices[rq.raw_minor];
	162
	163	if (command == RAW_SETBIND) {
	164	dev_t dev;
	165
	166	/*
	167	* This is like making block devices, so demand the
	168	* same capability
	169	*/
	170	if (!capable(CAP_SYS_ADMIN)) {
	171	err = -EPERM;
	172	goto out;
	173	}
	174
	175	/*
	176	* For now, we don't need to check that the underlying
	177	* block device is present or not: we can do that when
	178	* the raw device is opened. Just check that the
	179	* major/minor numbers make sense.
	180	*/
	181
	182	dev = MKDEV(rq.block_major, rq.block_minor);
	183	if ((rq.block_major == 0 && rq.block_minor != 0) \|\|
	184	MAJOR(dev) != rq.block_major \|\|
	185	MINOR(dev) != rq.block_minor) {
	186	err = -EINVAL;
	187	goto out;
	188	}
	189
8ed965d6	190	mutex_lock(&raw_mutex);
1da177e4	191	if (rawdev->inuse) {
8ed965d6	192	mutex_unlock(&raw_mutex);
1da177e4 LT	193	err = -EBUSY;
	194	goto out;
	195	}
	196	if (rawdev->binding) {
	197	bdput(rawdev->binding);
	198	module_put(THIS_MODULE);
	199	}
	200	if (rq.block_major == 0 && rq.block_minor == 0) {
	201	/* unbind */
	202	rawdev->binding = NULL;
38ca6c34	203	device_destroy(raw_class,
ca8eca68	204	MKDEV(RAW_MAJOR, rq.raw_minor));
1da177e4 LT	205	} else {
	206	rawdev->binding = bdget(dev);
	207	if (rawdev->binding == NULL)
	208	err = -ENOMEM;
	209	else {
	210	__module_get(THIS_MODULE);
	211	bind_device(&rq);
	212	}
	213	}
8ed965d6	214	mutex_unlock(&raw_mutex);
1da177e4 LT	215	} else {
	216	struct block_device *bdev;
	217
8ed965d6	218	mutex_lock(&raw_mutex);
1da177e4 LT	219	bdev = rawdev->binding;
	220	if (bdev) {
	221	rq.block_major = MAJOR(bdev->bd_dev);
	222	rq.block_minor = MINOR(bdev->bd_dev);
	223	} else {
	224	rq.block_major = rq.block_minor = 0;
	225	}
8ed965d6	226	mutex_unlock(&raw_mutex);
1da177e4 LT	227	if (copy_to_user((void __user *)arg, &rq, sizeof(rq))) {
	228	err = -EFAULT;
	229	goto out;
	230	}
	231	}
	232	break;
	233	default:
	234	err = -EINVAL;
	235	break;
	236	}
	237	out:
	238	return err;
	239	}
	240
62322d25	241	static const struct file_operations raw_fops = {
543ade1f	242	.read = do_sync_read,
1da177e4	243	.aio_read = generic_file_aio_read,
543ade1f	244	.write = do_sync_write,
027445c3	245	.aio_write = generic_file_aio_write_nolock,
1da177e4 LT	246	.open = raw_open,
	247	.release= raw_release,
	248	.ioctl = raw_ioctl,
1da177e4 LT	249	.owner = THIS_MODULE,
	250	};
	251
62322d25	252	static const struct file_operations raw_ctl_fops = {
1da177e4 LT	253	.ioctl = raw_ctl_ioctl,
	254	.open = raw_open,
	255	.owner = THIS_MODULE,
	256	};
	257
7e7654a9	258	static struct cdev raw_cdev;
1da177e4 LT	259
	260	static int __init raw_init(void)
	261	{
1da177e4	262	dev_t dev = MKDEV(RAW_MAJOR, 0);
3e26a423	263	int ret;
1da177e4	264
3e26a423 REB	265	ret = register_chrdev_region(dev, MAX_RAW_MINORS, "raw");
3e26a423 REB	266	if (ret)
1da177e4 LT	267	goto error;
	268
	269	cdev_init(&raw_cdev, &raw_fops);
3e26a423 REB	270	ret = cdev_add(&raw_cdev, dev, MAX_RAW_MINORS);
3e26a423 REB	271	if (ret) {
1da177e4	272	kobject_put(&raw_cdev.kobj);
3e26a423	273	goto error_region;
1da177e4 LT	274	}
1da177e4 LT	275
ca8eca68	276	raw_class = class_create(THIS_MODULE, "raw");
1da177e4 LT	277	if (IS_ERR(raw_class)) {
	278	printk(KERN_ERR "Error creating raw class.\n");
	279	cdev_del(&raw_cdev);
3e26a423 REB	280	ret = PTR_ERR(raw_class);
3e26a423 REB	281	goto error_region;
1da177e4	282	}
38ca6c34	283	device_create(raw_class, NULL, MKDEV(RAW_MAJOR, 0), "rawctl");
1da177e4	284
1da177e4 LT	285	return 0;
1da177e4 LT	286
3e26a423 REB	287	error_region:
3e26a423 REB	288	unregister_chrdev_region(dev, MAX_RAW_MINORS);
1da177e4	289	error:
3e26a423	290	return ret;
1da177e4 LT	291	}
	292
	293	static void __exit raw_exit(void)
	294	{
38ca6c34	295	device_destroy(raw_class, MKDEV(RAW_MAJOR, 0));
ca8eca68	296	class_destroy(raw_class);
1da177e4 LT	297	cdev_del(&raw_cdev);
	298	unregister_chrdev_region(MKDEV(RAW_MAJOR, 0), MAX_RAW_MINORS);
	299	}
	300
	301	module_init(raw_init);
	302	module_exit(raw_exit);
	303	MODULE_LICENSE("GPL");