[linux.git] / fs / fuse / cuse.c

/*
 * CUSE: Character device in Userspace
 *
 * Copyright (C) 2008-2009  SUSE Linux Products GmbH
 * Copyright (C) 2008-2009  Tejun Heo <[email protected]>
 *
 * This file is released under the GPLv2.
 *
 * CUSE enables character devices to be implemented from userland much
 * like FUSE allows filesystems.  On initialization /dev/cuse is
 * created.  By opening the file and replying to the CUSE_INIT request
 * userland CUSE server can create a character device.  After that the
 * operation is very similar to FUSE.
 *
 * A CUSE instance involves the following objects.
 *
 * cuse_conn	: contains fuse_conn and serves as bonding structure
 * channel	: file handle connected to the userland CUSE server
 * cdev		: the implemented character device
 * dev		: generic device for cdev
 *
 * Note that 'channel' is what 'dev' is in FUSE.  As CUSE deals with
 * devices, it's called 'channel' to reduce confusion.
 *
 * channel determines when the character device dies.  When channel is
 * closed, everything begins to destruct.  The cuse_conn is taken off
 * the lookup table preventing further access from cdev, cdev and
 * generic device are removed and the base reference of cuse_conn is
 * put.
 *
 * On each open, the matching cuse_conn is looked up and if found an
 * additional reference is taken which is released when the file is
 * closed.
 */

#include <linux/fuse.h>
#include <linux/cdev.h>
#include <linux/device.h>
#include <linux/file.h>
#include <linux/fs.h>
#include <linux/kdev_t.h>
#include <linux/kthread.h>
#include <linux/list.h>
#include <linux/magic.h>
#include <linux/miscdevice.h>
#include <linux/mutex.h>
#include <linux/slab.h>
#include <linux/stat.h>
#include <linux/module.h>

#include "fuse_i.h"

#define CUSE_CONNTBL_LEN	64

struct cuse_conn {
	struct list_head	list;	/* linked on cuse_conntbl */
	struct fuse_conn	fc;	/* fuse connection */
	struct cdev		*cdev;	/* associated character device */
	struct device		*dev;	/* device representing @cdev */

	/* init parameters, set once during initialization */
	bool			unrestricted_ioctl;
};

static DEFINE_MUTEX(cuse_lock);		/* protects registration */
static struct list_head cuse_conntbl[CUSE_CONNTBL_LEN];
static struct class *cuse_class;

static struct cuse_conn *fc_to_cc(struct fuse_conn *fc)
{
	return container_of(fc, struct cuse_conn, fc);
}

static struct list_head *cuse_conntbl_head(dev_t devt)
{
	return &cuse_conntbl[(MAJOR(devt) + MINOR(devt)) % CUSE_CONNTBL_LEN];
}


/**************************************************************************
 * CUSE frontend operations
 *
 * These are file operations for the character device.
 *
 * On open, CUSE opens a file from the FUSE mnt and stores it to
 * private_data of the open file.  All other ops call FUSE ops on the
 * FUSE file.
 */

static ssize_t cuse_read(struct file *file, char __user *buf, size_t count,
			 loff_t *ppos)
{
	loff_t pos = 0;
	struct iovec iov = { .iov_base = buf, .iov_len = count };

	return fuse_direct_io(file, &iov, 1, count, &pos, 0);
}

static ssize_t cuse_write(struct file *file, const char __user *buf,
			  size_t count, loff_t *ppos)
{
	loff_t pos = 0;
	struct iovec iov = { .iov_base = (void __user *)buf, .iov_len = count };

	/*
	 * No locking or generic_write_checks(), the server is
	 * responsible for locking and sanity checks.
	 */
	return fuse_direct_io(file, &iov, 1, count, &pos, 1);
}

static int cuse_open(struct inode *inode, struct file *file)
{
	dev_t devt = inode->i_cdev->dev;
	struct cuse_conn *cc = NULL, *pos;
	int rc;

	/* look up and get the connection */
	mutex_lock(&cuse_lock);
	list_for_each_entry(pos, cuse_conntbl_head(devt), list)
		if (pos->dev->devt == devt) {
			fuse_conn_get(&pos->fc);
			cc = pos;
			break;
		}
	mutex_unlock(&cuse_lock);

	/* dead? */
	if (!cc)
		return -ENODEV;

	/*
	 * Generic permission check is already done against the chrdev
	 * file, proceed to open.
	 */
	rc = fuse_do_open(&cc->fc, 0, file, 0);
	if (rc)
		fuse_conn_put(&cc->fc);
	return rc;
}

static int cuse_release(struct inode *inode, struct file *file)
{
	struct fuse_file *ff = file->private_data;
	struct fuse_conn *fc = ff->fc;

	fuse_sync_release(ff, file->f_flags);
	fuse_conn_put(fc);

	return 0;
}

static long cuse_file_ioctl(struct file *file, unsigned int cmd,
			    unsigned long arg)
{
	struct fuse_file *ff = file->private_data;
	struct cuse_conn *cc = fc_to_cc(ff->fc);
	unsigned int flags = 0;

	if (cc->unrestricted_ioctl)
		flags |= FUSE_IOCTL_UNRESTRICTED;

	return fuse_do_ioctl(file, cmd, arg, flags);
}

static long cuse_file_compat_ioctl(struct file *file, unsigned int cmd,
				   unsigned long arg)
{
	struct fuse_file *ff = file->private_data;
	struct cuse_conn *cc = fc_to_cc(ff->fc);
	unsigned int flags = FUSE_IOCTL_COMPAT;

	if (cc->unrestricted_ioctl)
		flags |= FUSE_IOCTL_UNRESTRICTED;

	return fuse_do_ioctl(file, cmd, arg, flags);
}

static const struct file_operations cuse_frontend_fops = {
	.owner			= THIS_MODULE,
	.read			= cuse_read,
	.write			= cuse_write,
	.open			= cuse_open,
	.release		= cuse_release,
	.unlocked_ioctl		= cuse_file_ioctl,
	.compat_ioctl		= cuse_file_compat_ioctl,
	.poll			= fuse_file_poll,
	.llseek		= noop_llseek,
};


/**************************************************************************
 * CUSE channel initialization and destruction
 */

struct cuse_devinfo {
	const char		*name;
};

/**
 * cuse_parse_one - parse one key=value pair
 * @pp: i/o parameter for the current position
 * @end: points to one past the end of the packed string
 * @keyp: out parameter for key
 * @valp: out parameter for value
 *
 * *@pp points to packed strings - "key0=val0\0key1=val1\0" which ends
 * at @end - 1.  This function parses one pair and set *@keyp to the
 * start of the key and *@valp to the start of the value.  Note that
 * the original string is modified such that the key string is
 * terminated with '\0'.  *@pp is updated to point to the next string.
 *
 * RETURNS:
 * 1 on successful parse, 0 on EOF, -errno on failure.
 */
static int cuse_parse_one(char **pp, char *end, char **keyp, char **valp)
{
	char *p = *pp;
	char *key, *val;

	while (p < end && *p == '\0')
		p++;
	if (p == end)
		return 0;

	if (end[-1] != '\0') {
		printk(KERN_ERR "CUSE: info not properly terminated\n");
		return -EINVAL;
	}

	key = val = p;
	p += strlen(p);

	if (valp) {
		strsep(&val, "=");
		if (!val)
			val = key + strlen(key);
		key = strstrip(key);
		val = strstrip(val);
	} else
		key = strstrip(key);

	if (!strlen(key)) {
		printk(KERN_ERR "CUSE: zero length info key specified\n");
		return -EINVAL;
	}

	*pp = p;
	*keyp = key;
	if (valp)
		*valp = val;

	return 1;
}

/**
 * cuse_parse_dev_info - parse device info
 * @p: device info string
 * @len: length of device info string
 * @devinfo: out parameter for parsed device info
 *
 * Parse @p to extract device info and store it into @devinfo.  String
 * pointed to by @p is modified by parsing and @devinfo points into
 * them, so @p shouldn't be freed while @devinfo is in use.
 *
 * RETURNS:
 * 0 on success, -errno on failure.
 */
static int cuse_parse_devinfo(char *p, size_t len, struct cuse_devinfo *devinfo)
{
	char *end = p + len;
	char *uninitialized_var(key), *uninitialized_var(val);
	int rc;

	while (true) {
		rc = cuse_parse_one(&p, end, &key, &val);
		if (rc < 0)
			return rc;
		if (!rc)
			break;
		if (strcmp(key, "DEVNAME") == 0)
			devinfo->name = val;
		else
			printk(KERN_WARNING "CUSE: unknown device info \"%s\"\n",
			       key);
	}

	if (!devinfo->name || !strlen(devinfo->name)) {
		printk(KERN_ERR "CUSE: DEVNAME unspecified\n");
		return -EINVAL;
	}

	return 0;
}

static void cuse_gendev_release(struct device *dev)
{
	kfree(dev);
}

/**
 * cuse_process_init_reply - finish initializing CUSE channel
 *
 * This function creates the character device and sets up all the
 * required data structures for it.  Please read the comment at the
 * top of this file for high level overview.
 */
static void cuse_process_init_reply(struct fuse_conn *fc, struct fuse_req *req)
{
	struct cuse_conn *cc = fc_to_cc(fc), *pos;
	struct cuse_init_out *arg = req->out.args[0].value;
	struct page *page = req->pages[0];
	struct cuse_devinfo devinfo = { };
	struct device *dev;
	struct cdev *cdev;
	dev_t devt;
	int rc, i;

	if (req->out.h.error ||
	    arg->major != FUSE_KERNEL_VERSION || arg->minor < 11) {
		goto err;
	}

	fc->minor = arg->minor;
	fc->max_read = max_t(unsigned, arg->max_read, 4096);
	fc->max_write = max_t(unsigned, arg->max_write, 4096);

	/* parse init reply */
	cc->unrestricted_ioctl = arg->flags & CUSE_UNRESTRICTED_IOCTL;

	rc = cuse_parse_devinfo(page_address(page), req->out.args[1].size,
				&devinfo);
	if (rc)
		goto err;

	/* determine and reserve devt */
	devt = MKDEV(arg->dev_major, arg->dev_minor);
	if (!MAJOR(devt))
		rc = alloc_chrdev_region(&devt, MINOR(devt), 1, devinfo.name);
	else
		rc = register_chrdev_region(devt, 1, devinfo.name);
	if (rc) {
		printk(KERN_ERR "CUSE: failed to register chrdev region\n");
		goto err;
	}

	/* devt determined, create device */
	rc = -ENOMEM;
	dev = kzalloc(sizeof(*dev), GFP_KERNEL);
	if (!dev)
		goto err_region;

	device_initialize(dev);
	dev_set_uevent_suppress(dev, 1);
	dev->class = cuse_class;
	dev->devt = devt;
	dev->release = cuse_gendev_release;
	dev_set_drvdata(dev, cc);
	dev_set_name(dev, "%s", devinfo.name);

	mutex_lock(&cuse_lock);

	/* make sure the device-name is unique */
	for (i = 0; i < CUSE_CONNTBL_LEN; ++i) {
		list_for_each_entry(pos, &cuse_conntbl[i], list)
			if (!strcmp(dev_name(pos->dev), dev_name(dev)))
				goto err_unlock;
	}

	rc = device_add(dev);
	if (rc)
		goto err_unlock;

	/* register cdev */
	rc = -ENOMEM;
	cdev = cdev_alloc();
	if (!cdev)
		goto err_unlock;

	cdev->owner = THIS_MODULE;
	cdev->ops = &cuse_frontend_fops;

	rc = cdev_add(cdev, devt, 1);
	if (rc)
		goto err_cdev;

	cc->dev = dev;
	cc->cdev = cdev;

	/* make the device available */
	list_add(&cc->list, cuse_conntbl_head(devt));
	mutex_unlock(&cuse_lock);

	/* announce device availability */
	dev_set_uevent_suppress(dev, 0);
	kobject_uevent(&dev->kobj, KOBJ_ADD);
out:
	kfree(arg);
	__free_page(page);
	return;

err_cdev:
	cdev_del(cdev);
err_unlock:
	mutex_unlock(&cuse_lock);
	put_device(dev);
err_region:
	unregister_chrdev_region(devt, 1);
err:
	fuse_conn_kill(fc);
	goto out;
}

static int cuse_send_init(struct cuse_conn *cc)
{
	int rc;
	struct fuse_req *req;
	struct page *page;
	struct fuse_conn *fc = &cc->fc;
	struct cuse_init_in *arg;
	void *outarg;

	BUILD_BUG_ON(CUSE_INIT_INFO_MAX > PAGE_SIZE);

	req = fuse_get_req(fc, 1);
	if (IS_ERR(req)) {
		rc = PTR_ERR(req);
		goto err;
	}

	rc = -ENOMEM;
	page = alloc_page(GFP_KERNEL | __GFP_ZERO);
	if (!page)
		goto err_put_req;

	outarg = kzalloc(sizeof(struct cuse_init_out), GFP_KERNEL);
	if (!outarg)
		goto err_free_page;

	arg = &req->misc.cuse_init_in;
	arg->major = FUSE_KERNEL_VERSION;
	arg->minor = FUSE_KERNEL_MINOR_VERSION;
	arg->flags |= CUSE_UNRESTRICTED_IOCTL;
	req->in.h.opcode = CUSE_INIT;
	req->in.numargs = 1;
	req->in.args[0].size = sizeof(struct cuse_init_in);
	req->in.args[0].value = arg;
	req->out.numargs = 2;
	req->out.args[0].size = sizeof(struct cuse_init_out);
	req->out.args[0].value = outarg;
	req->out.args[1].size = CUSE_INIT_INFO_MAX;
	req->out.argvar = 1;
	req->out.argpages = 1;
	req->pages[0] = page;
	req->page_descs[0].length = req->out.args[1].size;
	req->num_pages = 1;
	req->end = cuse_process_init_reply;
	fuse_request_send_background(fc, req);

	return 0;

err_free_page:
	__free_page(page);
err_put_req:
	fuse_put_request(fc, req);
err:
	return rc;
}

static void cuse_fc_release(struct fuse_conn *fc)
{
	struct cuse_conn *cc = fc_to_cc(fc);
	kfree(cc);
}

/**
 * cuse_channel_open - open method for /dev/cuse
 * @inode: inode for /dev/cuse
 * @file: file struct being opened
 *
 * Userland CUSE server can create a CUSE device by opening /dev/cuse
 * and replying to the initialization request kernel sends.  This
 * function is responsible for handling CUSE device initialization.
 * Because the fd opened by this function is used during
 * initialization, this function only creates cuse_conn and sends
 * init.  The rest is delegated to a kthread.
 *
 * RETURNS:
 * 0 on success, -errno on failure.
 */
static int cuse_channel_open(struct inode *inode, struct file *file)
{
	struct cuse_conn *cc;
	int rc;

	/* set up cuse_conn */
	cc = kzalloc(sizeof(*cc), GFP_KERNEL);
	if (!cc)
		return -ENOMEM;

	fuse_conn_init(&cc->fc);

	INIT_LIST_HEAD(&cc->list);
	cc->fc.release = cuse_fc_release;

	cc->fc.connected = 1;
	cc->fc.blocked = 0;
	rc = cuse_send_init(cc);
	if (rc) {
		fuse_conn_put(&cc->fc);
		return rc;
	}
	file->private_data = &cc->fc;	/* channel owns base reference to cc */

	return 0;
}

/**
 * cuse_channel_release - release method for /dev/cuse
 * @inode: inode for /dev/cuse
 * @file: file struct being closed
 *
 * Disconnect the channel, deregister CUSE device and initiate
 * destruction by putting the default reference.
 *
 * RETURNS:
 * 0 on success, -errno on failure.
 */
static int cuse_channel_release(struct inode *inode, struct file *file)
{
	struct cuse_conn *cc = fc_to_cc(file->private_data);
	int rc;

	/* remove from the conntbl, no more access from this point on */
	mutex_lock(&cuse_lock);
	list_del_init(&cc->list);
	mutex_unlock(&cuse_lock);

	/* remove device */
	if (cc->dev)
		device_unregister(cc->dev);
	if (cc->cdev) {
		unregister_chrdev_region(cc->cdev->dev, 1);
		cdev_del(cc->cdev);
	}

	rc = fuse_dev_release(inode, file);	/* puts the base reference */

	return rc;
}

static struct file_operations cuse_channel_fops; /* initialized during init */


/**************************************************************************
 * Misc stuff and module initializatiion
 *
 * CUSE exports the same set of attributes to sysfs as fusectl.
 */

static ssize_t cuse_class_waiting_show(struct device *dev,
				       struct device_attribute *attr, char *buf)
{
	struct cuse_conn *cc = dev_get_drvdata(dev);

	return sprintf(buf, "%d\n", atomic_read(&cc->fc.num_waiting));
}

static ssize_t cuse_class_abort_store(struct device *dev,
				      struct device_attribute *attr,
				      const char *buf, size_t count)
{
	struct cuse_conn *cc = dev_get_drvdata(dev);

	fuse_abort_conn(&cc->fc);
	return count;
}

static struct device_attribute cuse_class_dev_attrs[] = {
	__ATTR(waiting, S_IFREG | 0400, cuse_class_waiting_show, NULL),
	__ATTR(abort, S_IFREG | 0200, NULL, cuse_class_abort_store),
	{ }
};

static struct miscdevice cuse_miscdev = {
	.minor		= MISC_DYNAMIC_MINOR,
	.name		= "cuse",
	.fops		= &cuse_channel_fops,
};

static int __init cuse_init(void)
{
	int i, rc;

	/* init conntbl */
	for (i = 0; i < CUSE_CONNTBL_LEN; i++)
		INIT_LIST_HEAD(&cuse_conntbl[i]);

	/* inherit and extend fuse_dev_operations */
	cuse_channel_fops		= fuse_dev_operations;
	cuse_channel_fops.owner		= THIS_MODULE;
	cuse_channel_fops.open		= cuse_channel_open;
	cuse_channel_fops.release	= cuse_channel_release;

	cuse_class = class_create(THIS_MODULE, "cuse");
	if (IS_ERR(cuse_class))
		return PTR_ERR(cuse_class);

	cuse_class->dev_attrs = cuse_class_dev_attrs;

	rc = misc_register(&cuse_miscdev);
	if (rc) {
		class_destroy(cuse_class);
		return rc;
	}

	return 0;
}

static void __exit cuse_exit(void)
{
	misc_deregister(&cuse_miscdev);
	class_destroy(cuse_class);
}

module_init(cuse_init);
module_exit(cuse_exit);

MODULE_AUTHOR("Tejun Heo <[email protected]>");
MODULE_DESCRIPTION("Character device in Userspace");
MODULE_LICENSE("GPL");
Commit	Line	Data
151060ac TH	1	/*
	2	* CUSE: Character device in Userspace
	3	*
	4	* Copyright (C) 2008-2009 SUSE Linux Products GmbH
	5	* Copyright (C) 2008-2009 Tejun Heo <[email protected]>
	6	*
	7	* This file is released under the GPLv2.
	8	*
	9	* CUSE enables character devices to be implemented from userland much
	10	* like FUSE allows filesystems. On initialization /dev/cuse is
	11	* created. By opening the file and replying to the CUSE_INIT request
	12	* userland CUSE server can create a character device. After that the
	13	* operation is very similar to FUSE.
	14	*
	15	* A CUSE instance involves the following objects.
	16	*
	17	* cuse_conn : contains fuse_conn and serves as bonding structure
	18	* channel : file handle connected to the userland CUSE server
	19	* cdev : the implemented character device
	20	* dev : generic device for cdev
	21	*
	22	* Note that 'channel' is what 'dev' is in FUSE. As CUSE deals with
	23	* devices, it's called 'channel' to reduce confusion.
	24	*
	25	* channel determines when the character device dies. When channel is
	26	* closed, everything begins to destruct. The cuse_conn is taken off
	27	* the lookup table preventing further access from cdev, cdev and
	28	* generic device are removed and the base reference of cuse_conn is
	29	* put.
	30	*
	31	* On each open, the matching cuse_conn is looked up and if found an
	32	* additional reference is taken which is released when the file is
	33	* closed.
	34	*/
	35
	36	#include <linux/fuse.h>
	37	#include <linux/cdev.h>
	38	#include <linux/device.h>
	39	#include <linux/file.h>
	40	#include <linux/fs.h>
	41	#include <linux/kdev_t.h>
	42	#include <linux/kthread.h>
	43	#include <linux/list.h>
	44	#include <linux/magic.h>
	45	#include <linux/miscdevice.h>
	46	#include <linux/mutex.h>
5a0e3ad6	47	#include <linux/slab.h>
151060ac	48	#include <linux/stat.h>
143cb494	49	#include <linux/module.h>
151060ac TH	50
	51	#include "fuse_i.h"
	52
	53	#define CUSE_CONNTBL_LEN 64
	54
	55	struct cuse_conn {
	56	struct list_head list; /* linked on cuse_conntbl */
	57	struct fuse_conn fc; /* fuse connection */
	58	struct cdev cdev; / associated character device */
	59	struct device dev; / device representing @cdev */
	60
	61	/* init parameters, set once during initialization */
	62	bool unrestricted_ioctl;
	63	};
	64
8ce03fd7	65	static DEFINE_MUTEX(cuse_lock); /* protects registration */
151060ac TH	66	static struct list_head cuse_conntbl[CUSE_CONNTBL_LEN];
	67	static struct class *cuse_class;
	68
	69	static struct cuse_conn fc_to_cc(struct fuse_conn fc)
	70	{
	71	return container_of(fc, struct cuse_conn, fc);
	72	}
	73
	74	static struct list_head *cuse_conntbl_head(dev_t devt)
	75	{
	76	return &cuse_conntbl[(MAJOR(devt) + MINOR(devt)) % CUSE_CONNTBL_LEN];
	77	}
	78
	79
	80	/**************************************************************************
	81	* CUSE frontend operations
	82	*
	83	* These are file operations for the character device.
	84	*
	85	* On open, CUSE opens a file from the FUSE mnt and stores it to
	86	* private_data of the open file. All other ops call FUSE ops on the
	87	* FUSE file.
	88	*/
	89
	90	static ssize_t cuse_read(struct file file, char __user buf, size_t count,
	91	loff_t *ppos)
	92	{
	93	loff_t pos = 0;
fb05f41f	94	struct iovec iov = { .iov_base = buf, .iov_len = count };
151060ac	95
fb05f41f	96	return fuse_direct_io(file, &iov, 1, count, &pos, 0);
151060ac TH	97	}
	98
	99	static ssize_t cuse_write(struct file file, const char __user buf,
	100	size_t count, loff_t *ppos)
	101	{
	102	loff_t pos = 0;
fb05f41f MS	103	struct iovec iov = { .iov_base = (void __user *)buf, .iov_len = count };
fb05f41f MS	104
151060ac TH	105	/*
	106	* No locking or generic_write_checks(), the server is
	107	* responsible for locking and sanity checks.
	108	*/
fb05f41f	109	return fuse_direct_io(file, &iov, 1, count, &pos, 1);
151060ac TH	110	}
	111
	112	static int cuse_open(struct inode inode, struct file file)
	113	{
	114	dev_t devt = inode->i_cdev->dev;
	115	struct cuse_conn cc = NULL, pos;
	116	int rc;
	117
	118	/* look up and get the connection */
8ce03fd7	119	mutex_lock(&cuse_lock);
151060ac TH	120	list_for_each_entry(pos, cuse_conntbl_head(devt), list)
	121	if (pos->dev->devt == devt) {
	122	fuse_conn_get(&pos->fc);
	123	cc = pos;
	124	break;
	125	}
8ce03fd7	126	mutex_unlock(&cuse_lock);
151060ac TH	127
	128	/* dead? */
	129	if (!cc)
	130	return -ENODEV;
	131
	132	/*
	133	* Generic permission check is already done against the chrdev
	134	* file, proceed to open.
	135	*/
	136	rc = fuse_do_open(&cc->fc, 0, file, 0);
	137	if (rc)
	138	fuse_conn_put(&cc->fc);
	139	return rc;
	140	}
	141
	142	static int cuse_release(struct inode inode, struct file file)
	143	{
	144	struct fuse_file *ff = file->private_data;
	145	struct fuse_conn *fc = ff->fc;
	146
	147	fuse_sync_release(ff, file->f_flags);
	148	fuse_conn_put(fc);
	149
	150	return 0;
	151	}
	152
	153	static long cuse_file_ioctl(struct file *file, unsigned int cmd,
	154	unsigned long arg)
	155	{
	156	struct fuse_file *ff = file->private_data;
	157	struct cuse_conn *cc = fc_to_cc(ff->fc);
	158	unsigned int flags = 0;
	159
	160	if (cc->unrestricted_ioctl)
	161	flags \|= FUSE_IOCTL_UNRESTRICTED;
	162
	163	return fuse_do_ioctl(file, cmd, arg, flags);
	164	}
	165
	166	static long cuse_file_compat_ioctl(struct file *file, unsigned int cmd,
	167	unsigned long arg)
	168	{
	169	struct fuse_file *ff = file->private_data;
	170	struct cuse_conn *cc = fc_to_cc(ff->fc);
	171	unsigned int flags = FUSE_IOCTL_COMPAT;
	172
	173	if (cc->unrestricted_ioctl)
	174	flags \|= FUSE_IOCTL_UNRESTRICTED;
	175
	176	return fuse_do_ioctl(file, cmd, arg, flags);
	177	}
	178
	179	static const struct file_operations cuse_frontend_fops = {
	180	.owner = THIS_MODULE,
	181	.read = cuse_read,
	182	.write = cuse_write,
	183	.open = cuse_open,
	184	.release = cuse_release,
	185	.unlocked_ioctl = cuse_file_ioctl,
	186	.compat_ioctl = cuse_file_compat_ioctl,
	187	.poll = fuse_file_poll,
6038f373	188	.llseek = noop_llseek,
151060ac TH	189	};
	190
	191
	192	/**************************************************************************
	193	* CUSE channel initialization and destruction
	194	*/
	195
	196	struct cuse_devinfo {
	197	const char *name;
	198	};
	199
	200	/**
	201	* cuse_parse_one - parse one key=value pair
	202	* @pp: i/o parameter for the current position
	203	* @end: points to one past the end of the packed string
	204	* @keyp: out parameter for key
	205	* @valp: out parameter for value
	206	*
	207	* *@pp points to packed strings - "key0=val0\0key1=val1\0" which ends
	208	* at @end - 1. This function parses one pair and set *@keyp to the
	209	* start of the key and *@valp to the start of the value. Note that
	210	* the original string is modified such that the key string is
	211	* terminated with '\0'. *@pp is updated to point to the next string.
	212	*
	213	* RETURNS:
	214	* 1 on successful parse, 0 on EOF, -errno on failure.
	215	*/
	216	static int cuse_parse_one(char *pp, char end, char keyp, char valp)
	217	{
	218	char p = pp;
	219	char key, val;
	220
	221	while (p < end && *p == '\0')
	222	p++;
	223	if (p == end)
	224	return 0;
	225
	226	if (end[-1] != '\0') {
	227	printk(KERN_ERR "CUSE: info not properly terminated\n");
	228	return -EINVAL;
	229	}
	230
	231	key = val = p;
	232	p += strlen(p);
	233
	234	if (valp) {
	235	strsep(&val, "=");
	236	if (!val)
	237	val = key + strlen(key);
	238	key = strstrip(key);
	239	val = strstrip(val);
	240	} else
	241	key = strstrip(key);
	242
	243	if (!strlen(key)) {
	244	printk(KERN_ERR "CUSE: zero length info key specified\n");
	245	return -EINVAL;
	246	}
	247
	248	*pp = p;
	249	*keyp = key;
	250	if (valp)
	251	*valp = val;
	252
253	return 1;
254	}
255
256	/**
257	* cuse_parse_dev_info - parse device info
258	* @p: device info string
259	* @len: length of device info string
260	* @devinfo: out parameter for parsed device info
261	*
262	* Parse @p to extract device info and store it into @devinfo. String
263	* pointed to by @p is modified by parsing and @devinfo points into
264	* them, so @p shouldn't be freed while @devinfo is in use.
265	*
266	* RETURNS:
267	* 0 on success, -errno on failure.
268	*/
269	static int cuse_parse_devinfo(char p, size_t len, struct cuse_devinfo devinfo)
270	{
271	char *end = p + len;
e2560362	272	char uninitialized_var(key), uninitialized_var(val);
151060ac TH	273	int rc;
	274
	275	while (true) {
	276	rc = cuse_parse_one(&p, end, &key, &val);
	277	if (rc < 0)
	278	return rc;
	279	if (!rc)
	280	break;
	281	if (strcmp(key, "DEVNAME") == 0)
	282	devinfo->name = val;
	283	else
	284	printk(KERN_WARNING "CUSE: unknown device info \"%s\"\n",
	285	key);
	286	}
	287
	288	if (!devinfo->name \|\| !strlen(devinfo->name)) {
	289	printk(KERN_ERR "CUSE: DEVNAME unspecified\n");
	290	return -EINVAL;
	291	}
	292
	293	return 0;
	294	}
	295
	296	static void cuse_gendev_release(struct device *dev)
	297	{
	298	kfree(dev);
	299	}
	300
	301	/**
	302	* cuse_process_init_reply - finish initializing CUSE channel
	303	*
	304	* This function creates the character device and sets up all the
	305	* required data structures for it. Please read the comment at the
	306	* top of this file for high level overview.
	307	*/
	308	static void cuse_process_init_reply(struct fuse_conn fc, struct fuse_req req)
	309	{
30783587	310	struct cuse_conn cc = fc_to_cc(fc), pos;
07d5f69b	311	struct cuse_init_out *arg = req->out.args[0].value;
151060ac TH	312	struct page *page = req->pages[0];
	313	struct cuse_devinfo devinfo = { };
	314	struct device *dev;
	315	struct cdev *cdev;
	316	dev_t devt;
30783587	317	int rc, i;
151060ac TH	318
	319	if (req->out.h.error \|\|
	320	arg->major != FUSE_KERNEL_VERSION \|\| arg->minor < 11) {
	321	goto err;
	322	}
	323
	324	fc->minor = arg->minor;
	325	fc->max_read = max_t(unsigned, arg->max_read, 4096);
	326	fc->max_write = max_t(unsigned, arg->max_write, 4096);
	327
	328	/* parse init reply */
	329	cc->unrestricted_ioctl = arg->flags & CUSE_UNRESTRICTED_IOCTL;
	330
	331	rc = cuse_parse_devinfo(page_address(page), req->out.args[1].size,
	332	&devinfo);
	333	if (rc)
	334	goto err;
	335
	336	/* determine and reserve devt */
	337	devt = MKDEV(arg->dev_major, arg->dev_minor);
	338	if (!MAJOR(devt))
	339	rc = alloc_chrdev_region(&devt, MINOR(devt), 1, devinfo.name);
	340	else
	341	rc = register_chrdev_region(devt, 1, devinfo.name);
	342	if (rc) {
	343	printk(KERN_ERR "CUSE: failed to register chrdev region\n");
	344	goto err;
	345	}
	346
	347	/* devt determined, create device */
	348	rc = -ENOMEM;
	349	dev = kzalloc(sizeof(*dev), GFP_KERNEL);
	350	if (!dev)
	351	goto err_region;
	352
	353	device_initialize(dev);
	354	dev_set_uevent_suppress(dev, 1);
	355	dev->class = cuse_class;
	356	dev->devt = devt;
	357	dev->release = cuse_gendev_release;
	358	dev_set_drvdata(dev, cc);
	359	dev_set_name(dev, "%s", devinfo.name);
	360
30783587 DR	361	mutex_lock(&cuse_lock);
	362
	363	/* make sure the device-name is unique */
	364	for (i = 0; i < CUSE_CONNTBL_LEN; ++i) {
	365	list_for_each_entry(pos, &cuse_conntbl[i], list)
	366	if (!strcmp(dev_name(pos->dev), dev_name(dev)))
	367	goto err_unlock;
	368	}
	369
151060ac TH	370	rc = device_add(dev);
151060ac TH	371	if (rc)
30783587	372	goto err_unlock;
151060ac TH	373
	374	/* register cdev */
	375	rc = -ENOMEM;
	376	cdev = cdev_alloc();
	377	if (!cdev)
30783587	378	goto err_unlock;
151060ac TH	379
	380	cdev->owner = THIS_MODULE;
	381	cdev->ops = &cuse_frontend_fops;
	382
	383	rc = cdev_add(cdev, devt, 1);
	384	if (rc)
	385	goto err_cdev;
	386
	387	cc->dev = dev;
	388	cc->cdev = cdev;
	389
	390	/* make the device available */
151060ac	391	list_add(&cc->list, cuse_conntbl_head(devt));
8ce03fd7	392	mutex_unlock(&cuse_lock);
151060ac TH	393
	394	/* announce device availability */
	395	dev_set_uevent_suppress(dev, 0);
	396	kobject_uevent(&dev->kobj, KOBJ_ADD);
	397	out:
07d5f69b	398	kfree(arg);
151060ac TH	399	__free_page(page);
	400	return;
	401
	402	err_cdev:
	403	cdev_del(cdev);
30783587 DR	404	err_unlock:
30783587 DR	405	mutex_unlock(&cuse_lock);
151060ac TH	406	put_device(dev);
	407	err_region:
	408	unregister_chrdev_region(devt, 1);
	409	err:
8d39d801	410	fuse_conn_kill(fc);
151060ac TH	411	goto out;
	412	}
	413
	414	static int cuse_send_init(struct cuse_conn *cc)
	415	{
	416	int rc;
	417	struct fuse_req *req;
	418	struct page *page;
	419	struct fuse_conn *fc = &cc->fc;
	420	struct cuse_init_in *arg;
07d5f69b	421	void *outarg;
151060ac TH	422
	423	BUILD_BUG_ON(CUSE_INIT_INFO_MAX > PAGE_SIZE);
	424
b111c8c0	425	req = fuse_get_req(fc, 1);
151060ac TH	426	if (IS_ERR(req)) {
	427	rc = PTR_ERR(req);
	428	goto err;
	429	}
	430
	431	rc = -ENOMEM;
	432	page = alloc_page(GFP_KERNEL \| __GFP_ZERO);
	433	if (!page)
	434	goto err_put_req;
	435
07d5f69b MS	436	outarg = kzalloc(sizeof(struct cuse_init_out), GFP_KERNEL);
	437	if (!outarg)
	438	goto err_free_page;
	439
151060ac TH	440	arg = &req->misc.cuse_init_in;
	441	arg->major = FUSE_KERNEL_VERSION;
	442	arg->minor = FUSE_KERNEL_MINOR_VERSION;
	443	arg->flags \|= CUSE_UNRESTRICTED_IOCTL;
	444	req->in.h.opcode = CUSE_INIT;
	445	req->in.numargs = 1;
	446	req->in.args[0].size = sizeof(struct cuse_init_in);
	447	req->in.args[0].value = arg;
	448	req->out.numargs = 2;
	449	req->out.args[0].size = sizeof(struct cuse_init_out);
07d5f69b	450	req->out.args[0].value = outarg;
151060ac TH	451	req->out.args[1].size = CUSE_INIT_INFO_MAX;
	452	req->out.argvar = 1;
	453	req->out.argpages = 1;
	454	req->pages[0] = page;
85f40aec	455	req->page_descs[0].length = req->out.args[1].size;
151060ac TH	456	req->num_pages = 1;
	457	req->end = cuse_process_init_reply;
	458	fuse_request_send_background(fc, req);
	459
	460	return 0;
	461
07d5f69b MS	462	err_free_page:
07d5f69b MS	463	__free_page(page);
151060ac TH	464	err_put_req:
	465	fuse_put_request(fc, req);
	466	err:
	467	return rc;
	468	}
	469
	470	static void cuse_fc_release(struct fuse_conn *fc)
	471	{
	472	struct cuse_conn *cc = fc_to_cc(fc);
	473	kfree(cc);
	474	}
	475
	476	/**
	477	* cuse_channel_open - open method for /dev/cuse
	478	* @inode: inode for /dev/cuse
	479	* @file: file struct being opened
	480	*
	481	* Userland CUSE server can create a CUSE device by opening /dev/cuse
8272f4c9	482	* and replying to the initialization request kernel sends. This
151060ac TH	483	* function is responsible for handling CUSE device initialization.
	484	* Because the fd opened by this function is used during
	485	* initialization, this function only creates cuse_conn and sends
	486	* init. The rest is delegated to a kthread.
	487	*
	488	* RETURNS:
	489	* 0 on success, -errno on failure.
	490	*/
	491	static int cuse_channel_open(struct inode inode, struct file file)
	492	{
	493	struct cuse_conn *cc;
	494	int rc;
	495
	496	/* set up cuse_conn */
	497	cc = kzalloc(sizeof(*cc), GFP_KERNEL);
	498	if (!cc)
	499	return -ENOMEM;
	500
	501	fuse_conn_init(&cc->fc);
	502
	503	INIT_LIST_HEAD(&cc->list);
	504	cc->fc.release = cuse_fc_release;
	505
	506	cc->fc.connected = 1;
	507	cc->fc.blocked = 0;
	508	rc = cuse_send_init(cc);
	509	if (rc) {
	510	fuse_conn_put(&cc->fc);
	511	return rc;
	512	}
	513	file->private_data = &cc->fc; /* channel owns base reference to cc */
	514
	515	return 0;
	516	}
	517
	518	/**
	519	* cuse_channel_release - release method for /dev/cuse
	520	* @inode: inode for /dev/cuse
	521	* @file: file struct being closed
	522	*
	523	* Disconnect the channel, deregister CUSE device and initiate
	524	* destruction by putting the default reference.
	525	*
	526	* RETURNS:
	527	* 0 on success, -errno on failure.
	528	*/
	529	static int cuse_channel_release(struct inode inode, struct file file)
	530	{
	531	struct cuse_conn *cc = fc_to_cc(file->private_data);
	532	int rc;
	533
	534	/* remove from the conntbl, no more access from this point on */
8ce03fd7	535	mutex_lock(&cuse_lock);
151060ac	536	list_del_init(&cc->list);
8ce03fd7	537	mutex_unlock(&cuse_lock);
151060ac TH	538
	539	/* remove device */
	540	if (cc->dev)
	541	device_unregister(cc->dev);
	542	if (cc->cdev) {
	543	unregister_chrdev_region(cc->cdev->dev, 1);
	544	cdev_del(cc->cdev);
	545	}
	546
151060ac TH	547	rc = fuse_dev_release(inode, file); /* puts the base reference */
	548
	549	return rc;
	550	}
	551
	552	static struct file_operations cuse_channel_fops; /* initialized during init */
	553
	554
	555	/**************************************************************************
	556	* Misc stuff and module initializatiion
	557	*
	558	* CUSE exports the same set of attributes to sysfs as fusectl.
	559	*/
	560
	561	static ssize_t cuse_class_waiting_show(struct device *dev,
	562	struct device_attribute attr, char buf)
	563	{
	564	struct cuse_conn *cc = dev_get_drvdata(dev);
	565
	566	return sprintf(buf, "%d\n", atomic_read(&cc->fc.num_waiting));
	567	}
	568
	569	static ssize_t cuse_class_abort_store(struct device *dev,
	570	struct device_attribute *attr,
	571	const char *buf, size_t count)
	572	{
	573	struct cuse_conn *cc = dev_get_drvdata(dev);
	574
	575	fuse_abort_conn(&cc->fc);
	576	return count;
	577	}
	578
	579	static struct device_attribute cuse_class_dev_attrs[] = {
	580	__ATTR(waiting, S_IFREG \| 0400, cuse_class_waiting_show, NULL),
	581	__ATTR(abort, S_IFREG \| 0200, NULL, cuse_class_abort_store),
	582	{ }
	583	};
	584
	585	static struct miscdevice cuse_miscdev = {
	586	.minor = MISC_DYNAMIC_MINOR,
	587	.name = "cuse",
	588	.fops = &cuse_channel_fops,
	589	};
	590
	591	static int __init cuse_init(void)
	592	{
	593	int i, rc;
	594
	595	/* init conntbl */
	596	for (i = 0; i < CUSE_CONNTBL_LEN; i++)
	597	INIT_LIST_HEAD(&cuse_conntbl[i]);
	598
	599	/* inherit and extend fuse_dev_operations */
	600	cuse_channel_fops = fuse_dev_operations;
	601	cuse_channel_fops.owner = THIS_MODULE;
	602	cuse_channel_fops.open = cuse_channel_open;
	603	cuse_channel_fops.release = cuse_channel_release;
	604
	605	cuse_class = class_create(THIS_MODULE, "cuse");
	606	if (IS_ERR(cuse_class))
	607	return PTR_ERR(cuse_class);
	608
	609	cuse_class->dev_attrs = cuse_class_dev_attrs;
	610
611	rc = misc_register(&cuse_miscdev);
612	if (rc) {
613	class_destroy(cuse_class);
614	return rc;
615	}
616
617	return 0;
618	}
619
620	static void __exit cuse_exit(void)
621	{
622	misc_deregister(&cuse_miscdev);
623	class_destroy(cuse_class);
624	}
625
626	module_init(cuse_init);
627	module_exit(cuse_exit);
628
629	MODULE_AUTHOR("Tejun Heo <[email protected]>");
630	MODULE_DESCRIPTION("Character device in Userspace");
631	MODULE_LICENSE("GPL");