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/stat.h>
49#include <linux/module.h>
50#include <linux/uio.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_MUTEX(cuse_lock); /* protects registration */
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_iter(struct kiocb *kiocb, struct iov_iter *to)
92{
93 struct fuse_io_priv io = FUSE_IO_PRIV_SYNC(kiocb->ki_filp);
94 loff_t pos = 0;
95
96 return fuse_direct_io(&io, to, &pos, FUSE_DIO_CUSE);
97}
98
99static ssize_t cuse_write_iter(struct kiocb *kiocb, struct iov_iter *from)
100{
101 struct fuse_io_priv io = FUSE_IO_PRIV_SYNC(kiocb->ki_filp);
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(&io, from, &pos,
108 FUSE_DIO_WRITE | FUSE_DIO_CUSE);
109}
110
111static int cuse_open(struct inode *inode, struct file *file)
112{
113 dev_t devt = inode->i_cdev->dev;
114 struct cuse_conn *cc = NULL, *pos;
115 int rc;
116
117 /* look up and get the connection */
118 mutex_lock(&cuse_lock);
119 list_for_each_entry(pos, cuse_conntbl_head(devt), list)
120 if (pos->dev->devt == devt) {
121 fuse_conn_get(&pos->fc);
122 cc = pos;
123 break;
124 }
125 mutex_unlock(&cuse_lock);
126
127 /* dead? */
128 if (!cc)
129 return -ENODEV;
130
131 /*
132 * Generic permission check is already done against the chrdev
133 * file, proceed to open.
134 */
135 rc = fuse_do_open(&cc->fc, 0, file, 0);
136 if (rc)
137 fuse_conn_put(&cc->fc);
138 return rc;
139}
140
141static int cuse_release(struct inode *inode, struct file *file)
142{
143 struct fuse_file *ff = file->private_data;
144 struct fuse_conn *fc = ff->fc;
145
146 fuse_sync_release(ff, file->f_flags);
147 fuse_conn_put(fc);
148
149 return 0;
150}
151
152static long cuse_file_ioctl(struct file *file, unsigned int cmd,
153 unsigned long arg)
154{
155 struct fuse_file *ff = file->private_data;
156 struct cuse_conn *cc = fc_to_cc(ff->fc);
157 unsigned int flags = 0;
158
159 if (cc->unrestricted_ioctl)
160 flags |= FUSE_IOCTL_UNRESTRICTED;
161
162 return fuse_do_ioctl(file, cmd, arg, flags);
163}
164
165static long cuse_file_compat_ioctl(struct file *file, unsigned int cmd,
166 unsigned long arg)
167{
168 struct fuse_file *ff = file->private_data;
169 struct cuse_conn *cc = fc_to_cc(ff->fc);
170 unsigned int flags = FUSE_IOCTL_COMPAT;
171
172 if (cc->unrestricted_ioctl)
173 flags |= FUSE_IOCTL_UNRESTRICTED;
174
175 return fuse_do_ioctl(file, cmd, arg, flags);
176}
177
178static const struct file_operations cuse_frontend_fops = {
179 .owner = THIS_MODULE,
180 .read_iter = cuse_read_iter,
181 .write_iter = cuse_write_iter,
182 .open = cuse_open,
183 .release = cuse_release,
184 .unlocked_ioctl = cuse_file_ioctl,
185 .compat_ioctl = cuse_file_compat_ioctl,
186 .poll = fuse_file_poll,
187 .llseek = noop_llseek,
188};
189
190
191/**************************************************************************
192 * CUSE channel initialization and destruction
193 */
194
195struct cuse_devinfo {
196 const char *name;
197};
198
199/**
200 * cuse_parse_one - parse one key=value pair
201 * @pp: i/o parameter for the current position
202 * @end: points to one past the end of the packed string
203 * @keyp: out parameter for key
204 * @valp: out parameter for value
205 *
206 * *@pp points to packed strings - "key0=val0\0key1=val1\0" which ends
207 * at @end - 1. This function parses one pair and set *@keyp to the
208 * start of the key and *@valp to the start of the value. Note that
209 * the original string is modified such that the key string is
210 * terminated with '\0'. *@pp is updated to point to the next string.
211 *
212 * RETURNS:
213 * 1 on successful parse, 0 on EOF, -errno on failure.
214 */
215static int cuse_parse_one(char **pp, char *end, char **keyp, char **valp)
216{
217 char *p = *pp;
218 char *key, *val;
219
220 while (p < end && *p == '\0')
221 p++;
222 if (p == end)
223 return 0;
224
225 if (end[-1] != '\0') {
226 printk(KERN_ERR "CUSE: info not properly terminated\n");
227 return -EINVAL;
228 }
229
230 key = val = p;
231 p += strlen(p);
232
233 if (valp) {
234 strsep(&val, "=");
235 if (!val)
236 val = key + strlen(key);
237 key = strstrip(key);
238 val = strstrip(val);
239 } else
240 key = strstrip(key);
241
242 if (!strlen(key)) {
243 printk(KERN_ERR "CUSE: zero length info key specified\n");
244 return -EINVAL;
245 }
246
247 *pp = p;
248 *keyp = key;
249 if (valp)
250 *valp = val;
251
252 return 1;
253}
254
255/**
256 * cuse_parse_dev_info - parse device info
257 * @p: device info string
258 * @len: length of device info string
259 * @devinfo: out parameter for parsed device info
260 *
261 * Parse @p to extract device info and store it into @devinfo. String
262 * pointed to by @p is modified by parsing and @devinfo points into
263 * them, so @p shouldn't be freed while @devinfo is in use.
264 *
265 * RETURNS:
266 * 0 on success, -errno on failure.
267 */
268static int cuse_parse_devinfo(char *p, size_t len, struct cuse_devinfo *devinfo)
269{
270 char *end = p + len;
271 char *uninitialized_var(key), *uninitialized_var(val);
272 int rc;
273
274 while (true) {
275 rc = cuse_parse_one(&p, end, &key, &val);
276 if (rc < 0)
277 return rc;
278 if (!rc)
279 break;
280 if (strcmp(key, "DEVNAME") == 0)
281 devinfo->name = val;
282 else
283 printk(KERN_WARNING "CUSE: unknown device info \"%s\"\n",
284 key);
285 }
286
287 if (!devinfo->name || !strlen(devinfo->name)) {
288 printk(KERN_ERR "CUSE: DEVNAME unspecified\n");
289 return -EINVAL;
290 }
291
292 return 0;
293}
294
295static void cuse_gendev_release(struct device *dev)
296{
297 kfree(dev);
298}
299
300/**
301 * cuse_process_init_reply - finish initializing CUSE channel
302 *
303 * This function creates the character device and sets up all the
304 * required data structures for it. Please read the comment at the
305 * top of this file for high level overview.
306 */
307static void cuse_process_init_reply(struct fuse_conn *fc, struct fuse_req *req)
308{
309 struct cuse_conn *cc = fc_to_cc(fc), *pos;
310 struct cuse_init_out *arg = req->out.args[0].value;
311 struct page *page = req->pages[0];
312 struct cuse_devinfo devinfo = { };
313 struct device *dev;
314 struct cdev *cdev;
315 dev_t devt;
316 int rc, i;
317
318 if (req->out.h.error ||
319 arg->major != FUSE_KERNEL_VERSION || arg->minor < 11) {
320 goto err;
321 }
322
323 fc->minor = arg->minor;
324 fc->max_read = max_t(unsigned, arg->max_read, 4096);
325 fc->max_write = max_t(unsigned, arg->max_write, 4096);
326
327 /* parse init reply */
328 cc->unrestricted_ioctl = arg->flags & CUSE_UNRESTRICTED_IOCTL;
329
330 rc = cuse_parse_devinfo(page_address(page), req->out.args[1].size,
331 &devinfo);
332 if (rc)
333 goto err;
334
335 /* determine and reserve devt */
336 devt = MKDEV(arg->dev_major, arg->dev_minor);
337 if (!MAJOR(devt))
338 rc = alloc_chrdev_region(&devt, MINOR(devt), 1, devinfo.name);
339 else
340 rc = register_chrdev_region(devt, 1, devinfo.name);
341 if (rc) {
342 printk(KERN_ERR "CUSE: failed to register chrdev region\n");
343 goto err;
344 }
345
346 /* devt determined, create device */
347 rc = -ENOMEM;
348 dev = kzalloc(sizeof(*dev), GFP_KERNEL);
349 if (!dev)
350 goto err_region;
351
352 device_initialize(dev);
353 dev_set_uevent_suppress(dev, 1);
354 dev->class = cuse_class;
355 dev->devt = devt;
356 dev->release = cuse_gendev_release;
357 dev_set_drvdata(dev, cc);
358 dev_set_name(dev, "%s", devinfo.name);
359
360 mutex_lock(&cuse_lock);
361
362 /* make sure the device-name is unique */
363 for (i = 0; i < CUSE_CONNTBL_LEN; ++i) {
364 list_for_each_entry(pos, &cuse_conntbl[i], list)
365 if (!strcmp(dev_name(pos->dev), dev_name(dev)))
366 goto err_unlock;
367 }
368
369 rc = device_add(dev);
370 if (rc)
371 goto err_unlock;
372
373 /* register cdev */
374 rc = -ENOMEM;
375 cdev = cdev_alloc();
376 if (!cdev)
377 goto err_unlock;
378
379 cdev->owner = THIS_MODULE;
380 cdev->ops = &cuse_frontend_fops;
381
382 rc = cdev_add(cdev, devt, 1);
383 if (rc)
384 goto err_cdev;
385
386 cc->dev = dev;
387 cc->cdev = cdev;
388
389 /* make the device available */
390 list_add(&cc->list, cuse_conntbl_head(devt));
391 mutex_unlock(&cuse_lock);
392
393 /* announce device availability */
394 dev_set_uevent_suppress(dev, 0);
395 kobject_uevent(&dev->kobj, KOBJ_ADD);
396out:
397 kfree(arg);
398 __free_page(page);
399 return;
400
401err_cdev:
402 cdev_del(cdev);
403err_unlock:
404 mutex_unlock(&cuse_lock);
405 put_device(dev);
406err_region:
407 unregister_chrdev_region(devt, 1);
408err:
409 fuse_abort_conn(fc);
410 goto out;
411}
412
413static int cuse_send_init(struct cuse_conn *cc)
414{
415 int rc;
416 struct fuse_req *req;
417 struct page *page;
418 struct fuse_conn *fc = &cc->fc;
419 struct cuse_init_in *arg;
420 void *outarg;
421
422 BUILD_BUG_ON(CUSE_INIT_INFO_MAX > PAGE_SIZE);
423
424 req = fuse_get_req_for_background(fc, 1);
425 if (IS_ERR(req)) {
426 rc = PTR_ERR(req);
427 goto err;
428 }
429
430 rc = -ENOMEM;
431 page = alloc_page(GFP_KERNEL | __GFP_ZERO);
432 if (!page)
433 goto err_put_req;
434
435 outarg = kzalloc(sizeof(struct cuse_init_out), GFP_KERNEL);
436 if (!outarg)
437 goto err_free_page;
438
439 arg = &req->misc.cuse_init_in;
440 arg->major = FUSE_KERNEL_VERSION;
441 arg->minor = FUSE_KERNEL_MINOR_VERSION;
442 arg->flags |= CUSE_UNRESTRICTED_IOCTL;
443 req->in.h.opcode = CUSE_INIT;
444 req->in.numargs = 1;
445 req->in.args[0].size = sizeof(struct cuse_init_in);
446 req->in.args[0].value = arg;
447 req->out.numargs = 2;
448 req->out.args[0].size = sizeof(struct cuse_init_out);
449 req->out.args[0].value = outarg;
450 req->out.args[1].size = CUSE_INIT_INFO_MAX;
451 req->out.argvar = 1;
452 req->out.argpages = 1;
453 req->pages[0] = page;
454 req->page_descs[0].length = req->out.args[1].size;
455 req->num_pages = 1;
456 req->end = cuse_process_init_reply;
457 fuse_request_send_background(fc, req);
458
459 return 0;
460
461err_free_page:
462 __free_page(page);
463err_put_req:
464 fuse_put_request(fc, req);
465err:
466 return rc;
467}
468
469static void cuse_fc_release(struct fuse_conn *fc)
470{
471 struct cuse_conn *cc = fc_to_cc(fc);
472 kfree_rcu(cc, fc.rcu);
473}
474
475/**
476 * cuse_channel_open - open method for /dev/cuse
477 * @inode: inode for /dev/cuse
478 * @file: file struct being opened
479 *
480 * Userland CUSE server can create a CUSE device by opening /dev/cuse
481 * and replying to the initialization request kernel sends. This
482 * function is responsible for handling CUSE device initialization.
483 * Because the fd opened by this function is used during
484 * initialization, this function only creates cuse_conn and sends
485 * init. The rest is delegated to a kthread.
486 *
487 * RETURNS:
488 * 0 on success, -errno on failure.
489 */
490static int cuse_channel_open(struct inode *inode, struct file *file)
491{
492 struct fuse_dev *fud;
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 fud = fuse_dev_alloc(&cc->fc);
504 if (!fud) {
505 kfree(cc);
506 return -ENOMEM;
507 }
508
509 INIT_LIST_HEAD(&cc->list);
510 cc->fc.release = cuse_fc_release;
511
512 cc->fc.initialized = 1;
513 rc = cuse_send_init(cc);
514 if (rc) {
515 fuse_dev_free(fud);
516 return rc;
517 }
518 file->private_data = fud;
519
520 return 0;
521}
522
523/**
524 * cuse_channel_release - release method for /dev/cuse
525 * @inode: inode for /dev/cuse
526 * @file: file struct being closed
527 *
528 * Disconnect the channel, deregister CUSE device and initiate
529 * destruction by putting the default reference.
530 *
531 * RETURNS:
532 * 0 on success, -errno on failure.
533 */
534static int cuse_channel_release(struct inode *inode, struct file *file)
535{
536 struct fuse_dev *fud = file->private_data;
537 struct cuse_conn *cc = fc_to_cc(fud->fc);
538 int rc;
539
540 /* remove from the conntbl, no more access from this point on */
541 mutex_lock(&cuse_lock);
542 list_del_init(&cc->list);
543 mutex_unlock(&cuse_lock);
544
545 /* remove device */
546 if (cc->dev)
547 device_unregister(cc->dev);
548 if (cc->cdev) {
549 unregister_chrdev_region(cc->cdev->dev, 1);
550 cdev_del(cc->cdev);
551 }
552 /* Base reference is now owned by "fud" */
553 fuse_conn_put(&cc->fc);
554
555 rc = fuse_dev_release(inode, file); /* puts the base reference */
556
557 return rc;
558}
559
560static struct file_operations cuse_channel_fops; /* initialized during init */
561
562
563/**************************************************************************
564 * Misc stuff and module initializatiion
565 *
566 * CUSE exports the same set of attributes to sysfs as fusectl.
567 */
568
569static ssize_t cuse_class_waiting_show(struct device *dev,
570 struct device_attribute *attr, char *buf)
571{
572 struct cuse_conn *cc = dev_get_drvdata(dev);
573
574 return sprintf(buf, "%d\n", atomic_read(&cc->fc.num_waiting));
575}
576static DEVICE_ATTR(waiting, 0400, cuse_class_waiting_show, NULL);
577
578static ssize_t cuse_class_abort_store(struct device *dev,
579 struct device_attribute *attr,
580 const char *buf, size_t count)
581{
582 struct cuse_conn *cc = dev_get_drvdata(dev);
583
584 fuse_abort_conn(&cc->fc);
585 return count;
586}
587static DEVICE_ATTR(abort, 0200, NULL, cuse_class_abort_store);
588
589static struct attribute *cuse_class_dev_attrs[] = {
590 &dev_attr_waiting.attr,
591 &dev_attr_abort.attr,
592 NULL,
593};
594ATTRIBUTE_GROUPS(cuse_class_dev);
595
596static struct miscdevice cuse_miscdev = {
597 .minor = CUSE_MINOR,
598 .name = "cuse",
599 .fops = &cuse_channel_fops,
600};
601
602MODULE_ALIAS_MISCDEV(CUSE_MINOR);
603MODULE_ALIAS("devname:cuse");
604
605static int __init cuse_init(void)
606{
607 int i, rc;
608
609 /* init conntbl */
610 for (i = 0; i < CUSE_CONNTBL_LEN; i++)
611 INIT_LIST_HEAD(&cuse_conntbl[i]);
612
613 /* inherit and extend fuse_dev_operations */
614 cuse_channel_fops = fuse_dev_operations;
615 cuse_channel_fops.owner = THIS_MODULE;
616 cuse_channel_fops.open = cuse_channel_open;
617 cuse_channel_fops.release = cuse_channel_release;
618
619 cuse_class = class_create(THIS_MODULE, "cuse");
620 if (IS_ERR(cuse_class))
621 return PTR_ERR(cuse_class);
622
623 cuse_class->dev_groups = cuse_class_dev_groups;
624
625 rc = misc_register(&cuse_miscdev);
626 if (rc) {
627 class_destroy(cuse_class);
628 return rc;
629 }
630
631 return 0;
632}
633
634static void __exit cuse_exit(void)
635{
636 misc_deregister(&cuse_miscdev);
637 class_destroy(cuse_class);
638}
639
640module_init(cuse_init);
641module_exit(cuse_exit);
642
643MODULE_AUTHOR("Tejun Heo <tj@kernel.org>");
644MODULE_DESCRIPTION("Character device in Userspace");
645MODULE_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/stat.h>
49#include <linux/module.h>
50#include <linux/uio.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_MUTEX(cuse_lock); /* protects registration */
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_iter(struct kiocb *kiocb, struct iov_iter *to)
92{
93 struct fuse_io_priv io = FUSE_IO_PRIV_SYNC(kiocb->ki_filp);
94 loff_t pos = 0;
95
96 return fuse_direct_io(&io, to, &pos, FUSE_DIO_CUSE);
97}
98
99static ssize_t cuse_write_iter(struct kiocb *kiocb, struct iov_iter *from)
100{
101 struct fuse_io_priv io = FUSE_IO_PRIV_SYNC(kiocb->ki_filp);
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(&io, from, &pos,
108 FUSE_DIO_WRITE | FUSE_DIO_CUSE);
109}
110
111static int cuse_open(struct inode *inode, struct file *file)
112{
113 dev_t devt = inode->i_cdev->dev;
114 struct cuse_conn *cc = NULL, *pos;
115 int rc;
116
117 /* look up and get the connection */
118 mutex_lock(&cuse_lock);
119 list_for_each_entry(pos, cuse_conntbl_head(devt), list)
120 if (pos->dev->devt == devt) {
121 fuse_conn_get(&pos->fc);
122 cc = pos;
123 break;
124 }
125 mutex_unlock(&cuse_lock);
126
127 /* dead? */
128 if (!cc)
129 return -ENODEV;
130
131 /*
132 * Generic permission check is already done against the chrdev
133 * file, proceed to open.
134 */
135 rc = fuse_do_open(&cc->fc, 0, file, 0);
136 if (rc)
137 fuse_conn_put(&cc->fc);
138 return rc;
139}
140
141static int cuse_release(struct inode *inode, struct file *file)
142{
143 struct fuse_file *ff = file->private_data;
144 struct fuse_conn *fc = ff->fc;
145
146 fuse_sync_release(ff, file->f_flags);
147 fuse_conn_put(fc);
148
149 return 0;
150}
151
152static long cuse_file_ioctl(struct file *file, unsigned int cmd,
153 unsigned long arg)
154{
155 struct fuse_file *ff = file->private_data;
156 struct cuse_conn *cc = fc_to_cc(ff->fc);
157 unsigned int flags = 0;
158
159 if (cc->unrestricted_ioctl)
160 flags |= FUSE_IOCTL_UNRESTRICTED;
161
162 return fuse_do_ioctl(file, cmd, arg, flags);
163}
164
165static long cuse_file_compat_ioctl(struct file *file, unsigned int cmd,
166 unsigned long arg)
167{
168 struct fuse_file *ff = file->private_data;
169 struct cuse_conn *cc = fc_to_cc(ff->fc);
170 unsigned int flags = FUSE_IOCTL_COMPAT;
171
172 if (cc->unrestricted_ioctl)
173 flags |= FUSE_IOCTL_UNRESTRICTED;
174
175 return fuse_do_ioctl(file, cmd, arg, flags);
176}
177
178static const struct file_operations cuse_frontend_fops = {
179 .owner = THIS_MODULE,
180 .read_iter = cuse_read_iter,
181 .write_iter = cuse_write_iter,
182 .open = cuse_open,
183 .release = cuse_release,
184 .unlocked_ioctl = cuse_file_ioctl,
185 .compat_ioctl = cuse_file_compat_ioctl,
186 .poll = fuse_file_poll,
187 .llseek = noop_llseek,
188};
189
190
191/**************************************************************************
192 * CUSE channel initialization and destruction
193 */
194
195struct cuse_devinfo {
196 const char *name;
197};
198
199/**
200 * cuse_parse_one - parse one key=value pair
201 * @pp: i/o parameter for the current position
202 * @end: points to one past the end of the packed string
203 * @keyp: out parameter for key
204 * @valp: out parameter for value
205 *
206 * *@pp points to packed strings - "key0=val0\0key1=val1\0" which ends
207 * at @end - 1. This function parses one pair and set *@keyp to the
208 * start of the key and *@valp to the start of the value. Note that
209 * the original string is modified such that the key string is
210 * terminated with '\0'. *@pp is updated to point to the next string.
211 *
212 * RETURNS:
213 * 1 on successful parse, 0 on EOF, -errno on failure.
214 */
215static int cuse_parse_one(char **pp, char *end, char **keyp, char **valp)
216{
217 char *p = *pp;
218 char *key, *val;
219
220 while (p < end && *p == '\0')
221 p++;
222 if (p == end)
223 return 0;
224
225 if (end[-1] != '\0') {
226 printk(KERN_ERR "CUSE: info not properly terminated\n");
227 return -EINVAL;
228 }
229
230 key = val = p;
231 p += strlen(p);
232
233 if (valp) {
234 strsep(&val, "=");
235 if (!val)
236 val = key + strlen(key);
237 key = strstrip(key);
238 val = strstrip(val);
239 } else
240 key = strstrip(key);
241
242 if (!strlen(key)) {
243 printk(KERN_ERR "CUSE: zero length info key specified\n");
244 return -EINVAL;
245 }
246
247 *pp = p;
248 *keyp = key;
249 if (valp)
250 *valp = val;
251
252 return 1;
253}
254
255/**
256 * cuse_parse_dev_info - parse device info
257 * @p: device info string
258 * @len: length of device info string
259 * @devinfo: out parameter for parsed device info
260 *
261 * Parse @p to extract device info and store it into @devinfo. String
262 * pointed to by @p is modified by parsing and @devinfo points into
263 * them, so @p shouldn't be freed while @devinfo is in use.
264 *
265 * RETURNS:
266 * 0 on success, -errno on failure.
267 */
268static int cuse_parse_devinfo(char *p, size_t len, struct cuse_devinfo *devinfo)
269{
270 char *end = p + len;
271 char *uninitialized_var(key), *uninitialized_var(val);
272 int rc;
273
274 while (true) {
275 rc = cuse_parse_one(&p, end, &key, &val);
276 if (rc < 0)
277 return rc;
278 if (!rc)
279 break;
280 if (strcmp(key, "DEVNAME") == 0)
281 devinfo->name = val;
282 else
283 printk(KERN_WARNING "CUSE: unknown device info \"%s\"\n",
284 key);
285 }
286
287 if (!devinfo->name || !strlen(devinfo->name)) {
288 printk(KERN_ERR "CUSE: DEVNAME unspecified\n");
289 return -EINVAL;
290 }
291
292 return 0;
293}
294
295static void cuse_gendev_release(struct device *dev)
296{
297 kfree(dev);
298}
299
300/**
301 * cuse_process_init_reply - finish initializing CUSE channel
302 *
303 * This function creates the character device and sets up all the
304 * required data structures for it. Please read the comment at the
305 * top of this file for high level overview.
306 */
307static void cuse_process_init_reply(struct fuse_conn *fc, struct fuse_req *req)
308{
309 struct cuse_conn *cc = fc_to_cc(fc), *pos;
310 struct cuse_init_out *arg = req->out.args[0].value;
311 struct page *page = req->pages[0];
312 struct cuse_devinfo devinfo = { };
313 struct device *dev;
314 struct cdev *cdev;
315 dev_t devt;
316 int rc, i;
317
318 if (req->out.h.error ||
319 arg->major != FUSE_KERNEL_VERSION || arg->minor < 11) {
320 goto err;
321 }
322
323 fc->minor = arg->minor;
324 fc->max_read = max_t(unsigned, arg->max_read, 4096);
325 fc->max_write = max_t(unsigned, arg->max_write, 4096);
326
327 /* parse init reply */
328 cc->unrestricted_ioctl = arg->flags & CUSE_UNRESTRICTED_IOCTL;
329
330 rc = cuse_parse_devinfo(page_address(page), req->out.args[1].size,
331 &devinfo);
332 if (rc)
333 goto err;
334
335 /* determine and reserve devt */
336 devt = MKDEV(arg->dev_major, arg->dev_minor);
337 if (!MAJOR(devt))
338 rc = alloc_chrdev_region(&devt, MINOR(devt), 1, devinfo.name);
339 else
340 rc = register_chrdev_region(devt, 1, devinfo.name);
341 if (rc) {
342 printk(KERN_ERR "CUSE: failed to register chrdev region\n");
343 goto err;
344 }
345
346 /* devt determined, create device */
347 rc = -ENOMEM;
348 dev = kzalloc(sizeof(*dev), GFP_KERNEL);
349 if (!dev)
350 goto err_region;
351
352 device_initialize(dev);
353 dev_set_uevent_suppress(dev, 1);
354 dev->class = cuse_class;
355 dev->devt = devt;
356 dev->release = cuse_gendev_release;
357 dev_set_drvdata(dev, cc);
358 dev_set_name(dev, "%s", devinfo.name);
359
360 mutex_lock(&cuse_lock);
361
362 /* make sure the device-name is unique */
363 for (i = 0; i < CUSE_CONNTBL_LEN; ++i) {
364 list_for_each_entry(pos, &cuse_conntbl[i], list)
365 if (!strcmp(dev_name(pos->dev), dev_name(dev)))
366 goto err_unlock;
367 }
368
369 rc = device_add(dev);
370 if (rc)
371 goto err_unlock;
372
373 /* register cdev */
374 rc = -ENOMEM;
375 cdev = cdev_alloc();
376 if (!cdev)
377 goto err_unlock;
378
379 cdev->owner = THIS_MODULE;
380 cdev->ops = &cuse_frontend_fops;
381
382 rc = cdev_add(cdev, devt, 1);
383 if (rc)
384 goto err_cdev;
385
386 cc->dev = dev;
387 cc->cdev = cdev;
388
389 /* make the device available */
390 list_add(&cc->list, cuse_conntbl_head(devt));
391 mutex_unlock(&cuse_lock);
392
393 /* announce device availability */
394 dev_set_uevent_suppress(dev, 0);
395 kobject_uevent(&dev->kobj, KOBJ_ADD);
396out:
397 kfree(arg);
398 __free_page(page);
399 return;
400
401err_cdev:
402 cdev_del(cdev);
403err_unlock:
404 mutex_unlock(&cuse_lock);
405 put_device(dev);
406err_region:
407 unregister_chrdev_region(devt, 1);
408err:
409 fuse_abort_conn(fc);
410 goto out;
411}
412
413static int cuse_send_init(struct cuse_conn *cc)
414{
415 int rc;
416 struct fuse_req *req;
417 struct page *page;
418 struct fuse_conn *fc = &cc->fc;
419 struct cuse_init_in *arg;
420 void *outarg;
421
422 BUILD_BUG_ON(CUSE_INIT_INFO_MAX > PAGE_SIZE);
423
424 req = fuse_get_req_for_background(fc, 1);
425 if (IS_ERR(req)) {
426 rc = PTR_ERR(req);
427 goto err;
428 }
429
430 rc = -ENOMEM;
431 page = alloc_page(GFP_KERNEL | __GFP_ZERO);
432 if (!page)
433 goto err_put_req;
434
435 outarg = kzalloc(sizeof(struct cuse_init_out), GFP_KERNEL);
436 if (!outarg)
437 goto err_free_page;
438
439 arg = &req->misc.cuse_init_in;
440 arg->major = FUSE_KERNEL_VERSION;
441 arg->minor = FUSE_KERNEL_MINOR_VERSION;
442 arg->flags |= CUSE_UNRESTRICTED_IOCTL;
443 req->in.h.opcode = CUSE_INIT;
444 req->in.numargs = 1;
445 req->in.args[0].size = sizeof(struct cuse_init_in);
446 req->in.args[0].value = arg;
447 req->out.numargs = 2;
448 req->out.args[0].size = sizeof(struct cuse_init_out);
449 req->out.args[0].value = outarg;
450 req->out.args[1].size = CUSE_INIT_INFO_MAX;
451 req->out.argvar = 1;
452 req->out.argpages = 1;
453 req->pages[0] = page;
454 req->page_descs[0].length = req->out.args[1].size;
455 req->num_pages = 1;
456 req->end = cuse_process_init_reply;
457 fuse_request_send_background(fc, req);
458
459 return 0;
460
461err_free_page:
462 __free_page(page);
463err_put_req:
464 fuse_put_request(fc, req);
465err:
466 return rc;
467}
468
469static void cuse_fc_release(struct fuse_conn *fc)
470{
471 struct cuse_conn *cc = fc_to_cc(fc);
472 kfree_rcu(cc, fc.rcu);
473}
474
475/**
476 * cuse_channel_open - open method for /dev/cuse
477 * @inode: inode for /dev/cuse
478 * @file: file struct being opened
479 *
480 * Userland CUSE server can create a CUSE device by opening /dev/cuse
481 * and replying to the initialization request kernel sends. This
482 * function is responsible for handling CUSE device initialization.
483 * Because the fd opened by this function is used during
484 * initialization, this function only creates cuse_conn and sends
485 * init. The rest is delegated to a kthread.
486 *
487 * RETURNS:
488 * 0 on success, -errno on failure.
489 */
490static int cuse_channel_open(struct inode *inode, struct file *file)
491{
492 struct fuse_dev *fud;
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 fud = fuse_dev_alloc(&cc->fc);
504 if (!fud) {
505 kfree(cc);
506 return -ENOMEM;
507 }
508
509 INIT_LIST_HEAD(&cc->list);
510 cc->fc.release = cuse_fc_release;
511
512 cc->fc.initialized = 1;
513 rc = cuse_send_init(cc);
514 if (rc) {
515 fuse_dev_free(fud);
516 return rc;
517 }
518 file->private_data = fud;
519
520 return 0;
521}
522
523/**
524 * cuse_channel_release - release method for /dev/cuse
525 * @inode: inode for /dev/cuse
526 * @file: file struct being closed
527 *
528 * Disconnect the channel, deregister CUSE device and initiate
529 * destruction by putting the default reference.
530 *
531 * RETURNS:
532 * 0 on success, -errno on failure.
533 */
534static int cuse_channel_release(struct inode *inode, struct file *file)
535{
536 struct fuse_dev *fud = file->private_data;
537 struct cuse_conn *cc = fc_to_cc(fud->fc);
538 int rc;
539
540 /* remove from the conntbl, no more access from this point on */
541 mutex_lock(&cuse_lock);
542 list_del_init(&cc->list);
543 mutex_unlock(&cuse_lock);
544
545 /* remove device */
546 if (cc->dev)
547 device_unregister(cc->dev);
548 if (cc->cdev) {
549 unregister_chrdev_region(cc->cdev->dev, 1);
550 cdev_del(cc->cdev);
551 }
552 /* Base reference is now owned by "fud" */
553 fuse_conn_put(&cc->fc);
554
555 rc = fuse_dev_release(inode, file); /* puts the base reference */
556
557 return rc;
558}
559
560static struct file_operations cuse_channel_fops; /* initialized during init */
561
562
563/**************************************************************************
564 * Misc stuff and module initializatiion
565 *
566 * CUSE exports the same set of attributes to sysfs as fusectl.
567 */
568
569static ssize_t cuse_class_waiting_show(struct device *dev,
570 struct device_attribute *attr, char *buf)
571{
572 struct cuse_conn *cc = dev_get_drvdata(dev);
573
574 return sprintf(buf, "%d\n", atomic_read(&cc->fc.num_waiting));
575}
576static DEVICE_ATTR(waiting, 0400, cuse_class_waiting_show, NULL);
577
578static ssize_t cuse_class_abort_store(struct device *dev,
579 struct device_attribute *attr,
580 const char *buf, size_t count)
581{
582 struct cuse_conn *cc = dev_get_drvdata(dev);
583
584 fuse_abort_conn(&cc->fc);
585 return count;
586}
587static DEVICE_ATTR(abort, 0200, NULL, cuse_class_abort_store);
588
589static struct attribute *cuse_class_dev_attrs[] = {
590 &dev_attr_waiting.attr,
591 &dev_attr_abort.attr,
592 NULL,
593};
594ATTRIBUTE_GROUPS(cuse_class_dev);
595
596static struct miscdevice cuse_miscdev = {
597 .minor = CUSE_MINOR,
598 .name = "cuse",
599 .fops = &cuse_channel_fops,
600};
601
602MODULE_ALIAS_MISCDEV(CUSE_MINOR);
603MODULE_ALIAS("devname:cuse");
604
605static int __init cuse_init(void)
606{
607 int i, rc;
608
609 /* init conntbl */
610 for (i = 0; i < CUSE_CONNTBL_LEN; i++)
611 INIT_LIST_HEAD(&cuse_conntbl[i]);
612
613 /* inherit and extend fuse_dev_operations */
614 cuse_channel_fops = fuse_dev_operations;
615 cuse_channel_fops.owner = THIS_MODULE;
616 cuse_channel_fops.open = cuse_channel_open;
617 cuse_channel_fops.release = cuse_channel_release;
618
619 cuse_class = class_create(THIS_MODULE, "cuse");
620 if (IS_ERR(cuse_class))
621 return PTR_ERR(cuse_class);
622
623 cuse_class->dev_groups = cuse_class_dev_groups;
624
625 rc = misc_register(&cuse_miscdev);
626 if (rc) {
627 class_destroy(cuse_class);
628 return rc;
629 }
630
631 return 0;
632}
633
634static void __exit cuse_exit(void)
635{
636 misc_deregister(&cuse_miscdev);
637 class_destroy(cuse_class);
638}
639
640module_init(cuse_init);
641module_exit(cuse_exit);
642
643MODULE_AUTHOR("Tejun Heo <tj@kernel.org>");
644MODULE_DESCRIPTION("Character device in Userspace");
645MODULE_LICENSE("GPL");