[net-next-2.6.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 <linux/gfp.h>
#include <linux/compat.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);
	if (err)
		goto out;
	err = bd_claim(bdev, raw_open);
	if (err)
		goto out1;
	err = set_blocksize(bdev, bdev_logical_block_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, filp->f_mode);
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, filp->f_mode);
	return 0;
}

/*
 * Forward ioctls to the underlying block device.
 */
static long
raw_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_COMPAT
struct 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, mode_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;

	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;
	}
	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:
	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>
5a0e3ad6	22	#include <linux/gfp.h>
c4a04727	23	#include <linux/compat.h>
1da177e4 LT	24
	25	#include <asm/uaccess.h>
	26
	27	struct raw_device_data {
	28	struct block_device *binding;
	29	int inuse;
	30	};
	31
ca8eca68	32	static struct class *raw_class;
1da177e4	33	static struct raw_device_data raw_devices[MAX_RAW_MINORS];
8ed965d6	34	static DEFINE_MUTEX(raw_mutex);
62322d25	35	static const struct file_operations raw_ctl_fops; /* forward declaration */
1da177e4 LT	36
	37	/*
	38	* Open/close code for raw IO.
	39	*
	40	* We just rewrite the i_mapping for the /dev/raw/rawN file descriptor to
	41	* point at the blockdev's address_space and set the file handle to use
	42	* O_DIRECT.
	43	*
	44	* Set the device's soft blocksize to the minimum possible. This gives the
	45	* finest possible alignment and has no adverse impact on performance.
	46	*/
	47	static int raw_open(struct inode inode, struct file filp)
	48	{
	49	const int minor = iminor(inode);
	50	struct block_device *bdev;
	51	int err;
	52
	53	if (minor == 0) { /* It is the control device */
	54	filp->f_op = &raw_ctl_fops;
	55	return 0;
	56	}
	57
8ed965d6	58	mutex_lock(&raw_mutex);
1da177e4 LT	59
	60	/*
	61	* All we need to do on open is check that the device is bound.
	62	*/
	63	bdev = raw_devices[minor].binding;
	64	err = -ENODEV;
	65	if (!bdev)
	66	goto out;
	67	igrab(bdev->bd_inode);
572c4892	68	err = blkdev_get(bdev, filp->f_mode);
1da177e4 LT	69	if (err)
	70	goto out;
	71	err = bd_claim(bdev, raw_open);
	72	if (err)
	73	goto out1;
e1defc4f	74	err = set_blocksize(bdev, bdev_logical_block_size(bdev));
1da177e4 LT	75	if (err)
	76	goto out2;
	77	filp->f_flags \|= O_DIRECT;
	78	filp->f_mapping = bdev->bd_inode->i_mapping;
	79	if (++raw_devices[minor].inuse == 1)
a7113a96	80	filp->f_path.dentry->d_inode->i_mapping =
1da177e4 LT	81	bdev->bd_inode->i_mapping;
1da177e4 LT	82	filp->private_data = bdev;
8ed965d6	83	mutex_unlock(&raw_mutex);
1da177e4 LT	84	return 0;
	85
	86	out2:
	87	bd_release(bdev);
	88	out1:
9a1c3542	89	blkdev_put(bdev, filp->f_mode);
1da177e4	90	out:
8ed965d6	91	mutex_unlock(&raw_mutex);
1da177e4 LT	92	return err;
	93	}
	94
	95	/*
	96	* When the final fd which refers to this character-special node is closed, we
	97	* make its ->mapping point back at its own i_data.
	98	*/
	99	static int raw_release(struct inode inode, struct file filp)
	100	{
	101	const int minor= iminor(inode);
	102	struct block_device *bdev;
	103
8ed965d6	104	mutex_lock(&raw_mutex);
1da177e4 LT	105	bdev = raw_devices[minor].binding;
	106	if (--raw_devices[minor].inuse == 0) {
	107	/* Here inode->i_mapping == bdev->bd_inode->i_mapping */
	108	inode->i_mapping = &inode->i_data;
	109	inode->i_mapping->backing_dev_info = &default_backing_dev_info;
	110	}
8ed965d6	111	mutex_unlock(&raw_mutex);
1da177e4 LT	112
1da177e4 LT	113	bd_release(bdev);
9a1c3542	114	blkdev_put(bdev, filp->f_mode);
1da177e4 LT	115	return 0;
	116	}
	117
	118	/*
	119	* Forward ioctls to the underlying block device.
	120	*/
55929332 AB	121	static long
55929332 AB	122	raw_ioctl(struct file *filp, unsigned int command, unsigned long arg)
1da177e4 LT	123	{
1da177e4 LT	124	struct block_device *bdev = filp->private_data;
c4a04727 AV	125	return blkdev_ioctl(bdev, 0, command, arg);
	126	}
	127
	128	static int bind_set(int number, u64 major, u64 minor)
	129	{
	130	dev_t dev = MKDEV(major, minor);
	131	struct raw_device_data *rawdev;
	132	int err = 0;
	133
	134	if (number <= 0 \|\| number >= MAX_RAW_MINORS)
	135	return -EINVAL;
	136
	137	if (MAJOR(dev) != major \|\| MINOR(dev) != minor)
	138	return -EINVAL;
	139
	140	rawdev = &raw_devices[number];
1da177e4	141
c4a04727 AV	142	/*
	143	* This is like making block devices, so demand the
	144	* same capability
	145	*/
	146	if (!capable(CAP_SYS_ADMIN))
	147	return -EPERM;
	148
	149	/*
	150	* For now, we don't need to check that the underlying
	151	* block device is present or not: we can do that when
	152	* the raw device is opened. Just check that the
	153	* major/minor numbers make sense.
	154	*/
	155
	156	if (MAJOR(dev) == 0 && dev != 0)
	157	return -EINVAL;
55929332	158
c4a04727 AV	159	mutex_lock(&raw_mutex);
	160	if (rawdev->inuse) {
	161	mutex_unlock(&raw_mutex);
	162	return -EBUSY;
	163	}
	164	if (rawdev->binding) {
	165	bdput(rawdev->binding);
	166	module_put(THIS_MODULE);
	167	}
	168	if (!dev) {
	169	/* unbind */
	170	rawdev->binding = NULL;
	171	device_destroy(raw_class, MKDEV(RAW_MAJOR, number));
	172	} else {
	173	rawdev->binding = bdget(dev);
	174	if (rawdev->binding == NULL) {
	175	err = -ENOMEM;
	176	} else {
	177	dev_t raw = MKDEV(RAW_MAJOR, number);
	178	__module_get(THIS_MODULE);
	179	device_destroy(raw_class, raw);
	180	device_create(raw_class, NULL, raw, NULL,
	181	"raw%d", number);
	182	}
	183	}
	184	mutex_unlock(&raw_mutex);
	185	return err;
1da177e4 LT	186	}
1da177e4 LT	187
c4a04727	188	static int bind_get(int number, dev_t *dev)
1da177e4	189	{
c4a04727 AV	190	struct raw_device_data *rawdev;
	191	struct block_device *bdev;
	192
	193	if (number <= 0 \|\| number >= MAX_RAW_MINORS)
	194	return -EINVAL;
	195
	196	rawdev = &raw_devices[number];
	197
	198	mutex_lock(&raw_mutex);
	199	bdev = rawdev->binding;
	200	*dev = bdev ? bdev->bd_dev : 0;
	201	mutex_unlock(&raw_mutex);
	202	return 0;
1da177e4 LT	203	}
	204
	205	/*
	206	* Deal with ioctls against the raw-device control interface, to bind
	207	* and unbind other raw devices.
	208	*/
55929332 AB	209	static long raw_ctl_ioctl(struct file *filp, unsigned int command,
55929332 AB	210	unsigned long arg)
1da177e4 LT	211	{
1da177e4 LT	212	struct raw_config_request rq;
c4a04727 AV	213	dev_t dev;
c4a04727 AV	214	int err;
1da177e4 LT	215
	216	switch (command) {
	217	case RAW_SETBIND:
c4a04727 AV	218	if (copy_from_user(&rq, (void __user *) arg, sizeof(rq)))
	219	return -EFAULT;
	220
	221	return bind_set(rq.raw_minor, rq.block_major, rq.block_minor);
	222
1da177e4	223	case RAW_GETBIND:
c4a04727 AV	224	if (copy_from_user(&rq, (void __user *) arg, sizeof(rq)))
c4a04727 AV	225	return -EFAULT;
1da177e4	226
c4a04727 AV	227	err = bind_get(rq.raw_minor, &dev);
	228	if (err)
	229	return err;
1da177e4	230
c4a04727 AV	231	rq.block_major = MAJOR(dev);
c4a04727 AV	232	rq.block_minor = MINOR(dev);
1da177e4	233
c4a04727 AV	234	if (copy_to_user((void __user *)arg, &rq, sizeof(rq)))
	235	return -EFAULT;
	236
	237	return 0;
1da177e4	238	}
c4a04727 AV	239
	240	return -EINVAL;
	241	}
	242
	243	#ifdef CONFIG_COMPAT
	244	struct raw32_config_request {
	245	compat_int_t raw_minor;
	246	compat_u64 block_major;
	247	compat_u64 block_minor;
	248	};
	249
	250	static long raw_ctl_compat_ioctl(struct file *file, unsigned int cmd,
	251	unsigned long arg)
	252	{
	253	struct raw32_config_request __user *user_req = compat_ptr(arg);
	254	struct raw32_config_request rq;
	255	dev_t dev;
	256	int err = 0;
	257
	258	switch (cmd) {
	259	case RAW_SETBIND:
	260	if (copy_from_user(&rq, user_req, sizeof(rq)))
	261	return -EFAULT;
	262
	263	return bind_set(rq.raw_minor, rq.block_major, rq.block_minor);
	264
	265	case RAW_GETBIND:
	266	if (copy_from_user(&rq, user_req, sizeof(rq)))
	267	return -EFAULT;
	268
	269	err = bind_get(rq.raw_minor, &dev);
	270	if (err)
	271	return err;
	272
	273	rq.block_major = MAJOR(dev);
	274	rq.block_minor = MINOR(dev);
	275
	276	if (copy_to_user(user_req, &rq, sizeof(rq)))
	277	return -EFAULT;
	278
	279	return 0;
	280	}
	281
	282	return -EINVAL;
1da177e4	283	}
c4a04727	284	#endif
1da177e4	285
62322d25	286	static const struct file_operations raw_fops = {
55929332 AB	287	.read = do_sync_read,
	288	.aio_read = generic_file_aio_read,
	289	.write = do_sync_write,
	290	.aio_write = blkdev_aio_write,
	291	.fsync = blkdev_fsync,
	292	.open = raw_open,
	293	.release = raw_release,
	294	.unlocked_ioctl = raw_ioctl,
cb3b9cf8	295	.llseek = default_llseek,
55929332	296	.owner = THIS_MODULE,
1da177e4 LT	297	};
1da177e4 LT	298
62322d25	299	static const struct file_operations raw_ctl_fops = {
55929332	300	.unlocked_ioctl = raw_ctl_ioctl,
c4a04727 AV	301	#ifdef CONFIG_COMPAT
	302	.compat_ioctl = raw_ctl_compat_ioctl,
	303	#endif
55929332 AB	304	.open = raw_open,
55929332 AB	305	.owner = THIS_MODULE,
cb3b9cf8	306	.llseek = noop_llseek,
1da177e4 LT	307	};
1da177e4 LT	308
7e7654a9	309	static struct cdev raw_cdev;
1da177e4	310
e454cea2	311	static char raw_devnode(struct device dev, mode_t *mode)
6fd46933 KS	312	{
	313	return kasprintf(GFP_KERNEL, "raw/%s", dev_name(dev));
	314	}
	315
1da177e4 LT	316	static int __init raw_init(void)
1da177e4 LT	317	{
1da177e4	318	dev_t dev = MKDEV(RAW_MAJOR, 0);
3e26a423	319	int ret;
1da177e4	320
3e26a423 REB	321	ret = register_chrdev_region(dev, MAX_RAW_MINORS, "raw");
3e26a423 REB	322	if (ret)
1da177e4 LT	323	goto error;
	324
	325	cdev_init(&raw_cdev, &raw_fops);
3e26a423 REB	326	ret = cdev_add(&raw_cdev, dev, MAX_RAW_MINORS);
3e26a423 REB	327	if (ret) {
1da177e4	328	kobject_put(&raw_cdev.kobj);
3e26a423	329	goto error_region;
1da177e4 LT	330	}
1da177e4 LT	331
ca8eca68	332	raw_class = class_create(THIS_MODULE, "raw");
1da177e4 LT	333	if (IS_ERR(raw_class)) {
	334	printk(KERN_ERR "Error creating raw class.\n");
	335	cdev_del(&raw_cdev);
3e26a423 REB	336	ret = PTR_ERR(raw_class);
3e26a423 REB	337	goto error_region;
1da177e4	338	}
e454cea2	339	raw_class->devnode = raw_devnode;
03457cd4	340	device_create(raw_class, NULL, MKDEV(RAW_MAJOR, 0), NULL, "rawctl");
1da177e4	341
1da177e4 LT	342	return 0;
1da177e4 LT	343
3e26a423 REB	344	error_region:
3e26a423 REB	345	unregister_chrdev_region(dev, MAX_RAW_MINORS);
1da177e4	346	error:
3e26a423	347	return ret;
1da177e4 LT	348	}
	349
	350	static void __exit raw_exit(void)
	351	{
38ca6c34	352	device_destroy(raw_class, MKDEV(RAW_MAJOR, 0));
ca8eca68	353	class_destroy(raw_class);
1da177e4 LT	354	cdev_del(&raw_cdev);
	355	unregister_chrdev_region(MKDEV(RAW_MAJOR, 0), MAX_RAW_MINORS);
	356	}
	357
	358	module_init(raw_init);
	359	module_exit(raw_exit);
	360	MODULE_LICENSE("GPL");