[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/spinlock.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_SPINLOCK(cuse_lock);		/* protects cuse_conntbl */
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;

	return fuse_direct_io(file, buf, 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;
	/*
	 * No locking or generic_write_checks(), the server is
	 * responsible for locking and sanity checks.
	 */
	return fuse_direct_io(file, buf, 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 */
	spin_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;
		}
	spin_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 *key, *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);
	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;

	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);

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

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

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