[GitHub/exynos8895/android_kernel_samsung_universal8895.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/backing-dev.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;
	mutex_unlock(&raw_mutex);

	blkdev_put(bdev, filp->f_mode | FMODE_EXCL);
	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_iter	= blkdev_read_iter,
	.write_iter	= blkdev_write_iter,
	.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");
Commit	Line	Data
	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>
	13	#include <linux/major.h>
	14	#include <linux/blkdev.h>
	15	#include <linux/backing-dev.h>
	16	#include <linux/module.h>
	17	#include <linux/raw.h>
	18	#include <linux/capability.h>
	19	#include <linux/uio.h>
	20	#include <linux/cdev.h>
	21	#include <linux/device.h>
	22	#include <linux/mutex.h>
	23	#include <linux/gfp.h>
	24	#include <linux/compat.h>
	25	#include <linux/vmalloc.h>
	26
	27	#include <asm/uaccess.h>
	28
	29	struct raw_device_data {
	30	struct block_device *binding;
	31	int inuse;
	32	};
	33
	34	static struct class *raw_class;
	35	static struct raw_device_data *raw_devices;
	36	static DEFINE_MUTEX(raw_mutex);
	37	static const struct file_operations raw_ctl_fops; /* forward declaration */
	38
	39	static int max_raw_minors = MAX_RAW_MINORS;
	40
	41	module_param(max_raw_minors, int, 0);
	42	MODULE_PARM_DESC(max_raw_minors, "Maximum number of raw devices (1-65536)");
	43
	44	/*
	45	* Open/close code for raw IO.
	46	*
	47	* We just rewrite the i_mapping for the /dev/raw/rawN file descriptor to
	48	* point at the blockdev's address_space and set the file handle to use
	49	* O_DIRECT.
	50	*
	51	* Set the device's soft blocksize to the minimum possible. This gives the
	52	* finest possible alignment and has no adverse impact on performance.
	53	*/
	54	static int raw_open(struct inode inode, struct file filp)
	55	{
	56	const int minor = iminor(inode);
	57	struct block_device *bdev;
	58	int err;
	59
	60	if (minor == 0) { /* It is the control device */
	61	filp->f_op = &raw_ctl_fops;
	62	return 0;
	63	}
	64
	65	mutex_lock(&raw_mutex);
	66
	67	/*
	68	* All we need to do on open is check that the device is bound.
	69	*/
	70	bdev = raw_devices[minor].binding;
	71	err = -ENODEV;
	72	if (!bdev)
	73	goto out;
	74	igrab(bdev->bd_inode);
	75	err = blkdev_get(bdev, filp->f_mode \| FMODE_EXCL, raw_open);
	76	if (err)
	77	goto out;
	78	err = set_blocksize(bdev, bdev_logical_block_size(bdev));
	79	if (err)
	80	goto out1;
	81	filp->f_flags \|= O_DIRECT;
	82	filp->f_mapping = bdev->bd_inode->i_mapping;
	83	if (++raw_devices[minor].inuse == 1)
	84	file_inode(filp)->i_mapping =
	85	bdev->bd_inode->i_mapping;
	86	filp->private_data = bdev;
	87	mutex_unlock(&raw_mutex);
	88	return 0;
	89
	90	out1:
	91	blkdev_put(bdev, filp->f_mode \| FMODE_EXCL);
	92	out:
	93	mutex_unlock(&raw_mutex);
	94	return err;
	95	}
	96
	97	/*
	98	* When the final fd which refers to this character-special node is closed, we
	99	* make its ->mapping point back at its own i_data.
	100	*/
	101	static int raw_release(struct inode inode, struct file filp)
	102	{
	103	const int minor= iminor(inode);
	104	struct block_device *bdev;
	105
	106	mutex_lock(&raw_mutex);
	107	bdev = raw_devices[minor].binding;
	108	if (--raw_devices[minor].inuse == 0)
	109	/* Here inode->i_mapping == bdev->bd_inode->i_mapping */
	110	inode->i_mapping = &inode->i_data;
	111	mutex_unlock(&raw_mutex);
	112
	113	blkdev_put(bdev, filp->f_mode \| FMODE_EXCL);
	114	return 0;
	115	}
	116
	117	/*
	118	* Forward ioctls to the underlying block device.
	119	*/
	120	static long
	121	raw_ioctl(struct file *filp, unsigned int command, unsigned long arg)
	122	{
	123	struct block_device *bdev = filp->private_data;
	124	return blkdev_ioctl(bdev, 0, command, arg);
	125	}
	126
	127	static int bind_set(int number, u64 major, u64 minor)
	128	{
	129	dev_t dev = MKDEV(major, minor);
	130	struct raw_device_data *rawdev;
	131	int err = 0;
	132
	133	if (number <= 0 \|\| number >= max_raw_minors)
	134	return -EINVAL;
	135
	136	if (MAJOR(dev) != major \|\| MINOR(dev) != minor)
	137	return -EINVAL;
	138
	139	rawdev = &raw_devices[number];
	140
	141	/*
	142	* This is like making block devices, so demand the
	143	* same capability
	144	*/
	145	if (!capable(CAP_SYS_ADMIN))
	146	return -EPERM;
	147
	148	/*
	149	* For now, we don't need to check that the underlying
	150	* block device is present or not: we can do that when
	151	* the raw device is opened. Just check that the
	152	* major/minor numbers make sense.
	153	*/
	154
	155	if (MAJOR(dev) == 0 && dev != 0)
	156	return -EINVAL;
	157
	158	mutex_lock(&raw_mutex);
	159	if (rawdev->inuse) {
	160	mutex_unlock(&raw_mutex);
	161	return -EBUSY;
	162	}
	163	if (rawdev->binding) {
	164	bdput(rawdev->binding);
	165	module_put(THIS_MODULE);
	166	}
	167	if (!dev) {
	168	/* unbind */
	169	rawdev->binding = NULL;
	170	device_destroy(raw_class, MKDEV(RAW_MAJOR, number));
	171	} else {
	172	rawdev->binding = bdget(dev);
	173	if (rawdev->binding == NULL) {
	174	err = -ENOMEM;
	175	} else {
	176	dev_t raw = MKDEV(RAW_MAJOR, number);
	177	__module_get(THIS_MODULE);
	178	device_destroy(raw_class, raw);
	179	device_create(raw_class, NULL, raw, NULL,
	180	"raw%d", number);
	181	}
	182	}
	183	mutex_unlock(&raw_mutex);
	184	return err;
	185	}
	186
	187	static int bind_get(int number, dev_t *dev)
	188	{
	189	struct raw_device_data *rawdev;
	190	struct block_device *bdev;
	191
	192	if (number <= 0 \|\| number >= max_raw_minors)
	193	return -EINVAL;
	194
	195	rawdev = &raw_devices[number];
	196
	197	mutex_lock(&raw_mutex);
	198	bdev = rawdev->binding;
	199	*dev = bdev ? bdev->bd_dev : 0;
	200	mutex_unlock(&raw_mutex);
	201	return 0;
	202	}
	203
	204	/*
	205	* Deal with ioctls against the raw-device control interface, to bind
	206	* and unbind other raw devices.
	207	*/
	208	static long raw_ctl_ioctl(struct file *filp, unsigned int command,
	209	unsigned long arg)
	210	{
	211	struct raw_config_request rq;
	212	dev_t dev;
	213	int err;
	214
	215	switch (command) {
	216	case RAW_SETBIND:
	217	if (copy_from_user(&rq, (void __user *) arg, sizeof(rq)))
	218	return -EFAULT;
	219
	220	return bind_set(rq.raw_minor, rq.block_major, rq.block_minor);
	221
	222	case RAW_GETBIND:
	223	if (copy_from_user(&rq, (void __user *) arg, sizeof(rq)))
	224	return -EFAULT;
	225
	226	err = bind_get(rq.raw_minor, &dev);
	227	if (err)
	228	return err;
	229
	230	rq.block_major = MAJOR(dev);
	231	rq.block_minor = MINOR(dev);
	232
	233	if (copy_to_user((void __user *)arg, &rq, sizeof(rq)))
	234	return -EFAULT;
	235
	236	return 0;
	237	}
	238
	239	return -EINVAL;
	240	}
	241
	242	#ifdef CONFIG_COMPAT
	243	struct raw32_config_request {
	244	compat_int_t raw_minor;
	245	compat_u64 block_major;
	246	compat_u64 block_minor;
	247	};
	248
	249	static long raw_ctl_compat_ioctl(struct file *file, unsigned int cmd,
	250	unsigned long arg)
	251	{
	252	struct raw32_config_request __user *user_req = compat_ptr(arg);
	253	struct raw32_config_request rq;
	254	dev_t dev;
	255	int err = 0;
	256
	257	switch (cmd) {
	258	case RAW_SETBIND:
	259	if (copy_from_user(&rq, user_req, sizeof(rq)))
	260	return -EFAULT;
	261
	262	return bind_set(rq.raw_minor, rq.block_major, rq.block_minor);
	263
	264	case RAW_GETBIND:
	265	if (copy_from_user(&rq, user_req, sizeof(rq)))
	266	return -EFAULT;
	267
	268	err = bind_get(rq.raw_minor, &dev);
	269	if (err)
	270	return err;
	271
	272	rq.block_major = MAJOR(dev);
	273	rq.block_minor = MINOR(dev);
	274
	275	if (copy_to_user(user_req, &rq, sizeof(rq)))
	276	return -EFAULT;
	277
	278	return 0;
	279	}
	280
	281	return -EINVAL;
	282	}
	283	#endif
	284
	285	static const struct file_operations raw_fops = {
	286	.read_iter = blkdev_read_iter,
	287	.write_iter = blkdev_write_iter,
	288	.fsync = blkdev_fsync,
	289	.open = raw_open,
	290	.release = raw_release,
	291	.unlocked_ioctl = raw_ioctl,
	292	.llseek = default_llseek,
	293	.owner = THIS_MODULE,
	294	};
	295
	296	static const struct file_operations raw_ctl_fops = {
	297	.unlocked_ioctl = raw_ctl_ioctl,
	298	#ifdef CONFIG_COMPAT
	299	.compat_ioctl = raw_ctl_compat_ioctl,
	300	#endif
	301	.open = raw_open,
	302	.owner = THIS_MODULE,
	303	.llseek = noop_llseek,
	304	};
	305
	306	static struct cdev raw_cdev;
	307
	308	static char raw_devnode(struct device dev, umode_t *mode)
	309	{
	310	return kasprintf(GFP_KERNEL, "raw/%s", dev_name(dev));
	311	}
	312
	313	static int __init raw_init(void)
	314	{
	315	dev_t dev = MKDEV(RAW_MAJOR, 0);
	316	int ret;
	317
	318	if (max_raw_minors < 1 \|\| max_raw_minors > 65536) {
	319	printk(KERN_WARNING "raw: invalid max_raw_minors (must be"
	320	" between 1 and 65536), using %d\n", MAX_RAW_MINORS);
	321	max_raw_minors = MAX_RAW_MINORS;
	322	}
	323
	324	raw_devices = vzalloc(sizeof(struct raw_device_data) * max_raw_minors);
	325	if (!raw_devices) {
	326	printk(KERN_ERR "Not enough memory for raw device structures\n");
	327	ret = -ENOMEM;
	328	goto error;
	329	}
	330
	331	ret = register_chrdev_region(dev, max_raw_minors, "raw");
	332	if (ret)
	333	goto error;
	334
	335	cdev_init(&raw_cdev, &raw_fops);
	336	ret = cdev_add(&raw_cdev, dev, max_raw_minors);
	337	if (ret) {
	338	goto error_region;
	339	}
	340
	341	raw_class = class_create(THIS_MODULE, "raw");
	342	if (IS_ERR(raw_class)) {
	343	printk(KERN_ERR "Error creating raw class.\n");
	344	cdev_del(&raw_cdev);
	345	ret = PTR_ERR(raw_class);
	346	goto error_region;
	347	}
	348	raw_class->devnode = raw_devnode;
	349	device_create(raw_class, NULL, MKDEV(RAW_MAJOR, 0), NULL, "rawctl");
	350
	351	return 0;
	352
	353	error_region:
	354	unregister_chrdev_region(dev, max_raw_minors);
	355	error:
	356	vfree(raw_devices);
	357	return ret;
	358	}
	359
	360	static void __exit raw_exit(void)
	361	{
	362	device_destroy(raw_class, MKDEV(RAW_MAJOR, 0));
	363	class_destroy(raw_class);
	364	cdev_del(&raw_cdev);
	365	unregister_chrdev_region(MKDEV(RAW_MAJOR, 0), max_raw_minors);
	366	}
	367
	368	module_init(raw_init);
	369	module_exit(raw_exit);
	370	MODULE_LICENSE("GPL");