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