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35#define pr_fmt(fmt) "CUSE: " fmt
36
37#include <linux/fuse.h>
38#include <linux/cdev.h>
39#include <linux/device.h>
40#include <linux/file.h>
41#include <linux/fs.h>
42#include <linux/kdev_t.h>
43#include <linux/kthread.h>
44#include <linux/list.h>
45#include <linux/magic.h>
46#include <linux/miscdevice.h>
47#include <linux/mutex.h>
48#include <linux/slab.h>
49#include <linux/stat.h>
50#include <linux/module.h>
51#include <linux/uio.h>
52#include <linux/user_namespace.h>
53
54#include "fuse_i.h"
55
56#define CUSE_CONNTBL_LEN 64
57
58struct cuse_conn {
59 struct list_head list;
60 struct fuse_mount fm;
61 struct fuse_conn fc;
62 struct cdev *cdev;
63 struct device *dev;
64
65
66 bool unrestricted_ioctl;
67};
68
69static DEFINE_MUTEX(cuse_lock);
70static struct list_head cuse_conntbl[CUSE_CONNTBL_LEN];
71static struct class *cuse_class;
72
73static struct cuse_conn *fc_to_cc(struct fuse_conn *fc)
74{
75 return container_of(fc, struct cuse_conn, fc);
76}
77
78static struct list_head *cuse_conntbl_head(dev_t devt)
79{
80 return &cuse_conntbl[(MAJOR(devt) + MINOR(devt)) % CUSE_CONNTBL_LEN];
81}
82
83
84
85
86
87
88
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90
91
92
93
94static ssize_t cuse_read_iter(struct kiocb *kiocb, struct iov_iter *to)
95{
96 struct fuse_io_priv io = FUSE_IO_PRIV_SYNC(kiocb);
97 loff_t pos = 0;
98
99 return fuse_direct_io(&io, to, &pos, FUSE_DIO_CUSE);
100}
101
102static ssize_t cuse_write_iter(struct kiocb *kiocb, struct iov_iter *from)
103{
104 struct fuse_io_priv io = FUSE_IO_PRIV_SYNC(kiocb);
105 loff_t pos = 0;
106
107
108
109
110 return fuse_direct_io(&io, from, &pos,
111 FUSE_DIO_WRITE | FUSE_DIO_CUSE);
112}
113
114static int cuse_open(struct inode *inode, struct file *file)
115{
116 dev_t devt = inode->i_cdev->dev;
117 struct cuse_conn *cc = NULL, *pos;
118 int rc;
119
120
121 mutex_lock(&cuse_lock);
122 list_for_each_entry(pos, cuse_conntbl_head(devt), list)
123 if (pos->dev->devt == devt) {
124 fuse_conn_get(&pos->fc);
125 cc = pos;
126 break;
127 }
128 mutex_unlock(&cuse_lock);
129
130
131 if (!cc)
132 return -ENODEV;
133
134
135
136
137
138 rc = fuse_do_open(&cc->fm, 0, file, 0);
139 if (rc)
140 fuse_conn_put(&cc->fc);
141 return rc;
142}
143
144static int cuse_release(struct inode *inode, struct file *file)
145{
146 struct fuse_file *ff = file->private_data;
147 struct fuse_mount *fm = ff->fm;
148
149 fuse_sync_release(NULL, ff, file->f_flags);
150 fuse_conn_put(fm->fc);
151
152 return 0;
153}
154
155static long cuse_file_ioctl(struct file *file, unsigned int cmd,
156 unsigned long arg)
157{
158 struct fuse_file *ff = file->private_data;
159 struct cuse_conn *cc = fc_to_cc(ff->fm->fc);
160 unsigned int flags = 0;
161
162 if (cc->unrestricted_ioctl)
163 flags |= FUSE_IOCTL_UNRESTRICTED;
164
165 return fuse_do_ioctl(file, cmd, arg, flags);
166}
167
168static long cuse_file_compat_ioctl(struct file *file, unsigned int cmd,
169 unsigned long arg)
170{
171 struct fuse_file *ff = file->private_data;
172 struct cuse_conn *cc = fc_to_cc(ff->fm->fc);
173 unsigned int flags = FUSE_IOCTL_COMPAT;
174
175 if (cc->unrestricted_ioctl)
176 flags |= FUSE_IOCTL_UNRESTRICTED;
177
178 return fuse_do_ioctl(file, cmd, arg, flags);
179}
180
181static const struct file_operations cuse_frontend_fops = {
182 .owner = THIS_MODULE,
183 .read_iter = cuse_read_iter,
184 .write_iter = cuse_write_iter,
185 .open = cuse_open,
186 .release = cuse_release,
187 .unlocked_ioctl = cuse_file_ioctl,
188 .compat_ioctl = cuse_file_compat_ioctl,
189 .poll = fuse_file_poll,
190 .llseek = noop_llseek,
191};
192
193
194
195
196
197
198struct cuse_devinfo {
199 const char *name;
200};
201
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217
218static int cuse_parse_one(char **pp, char *end, char **keyp, char **valp)
219{
220 char *p = *pp;
221 char *key, *val;
222
223 while (p < end && *p == '\0')
224 p++;
225 if (p == end)
226 return 0;
227
228 if (end[-1] != '\0') {
229 pr_err("info not properly terminated\n");
230 return -EINVAL;
231 }
232
233 key = val = p;
234 p += strlen(p);
235
236 if (valp) {
237 strsep(&val, "=");
238 if (!val)
239 val = key + strlen(key);
240 key = strstrip(key);
241 val = strstrip(val);
242 } else
243 key = strstrip(key);
244
245 if (!strlen(key)) {
246 pr_err("zero length info key specified\n");
247 return -EINVAL;
248 }
249
250 *pp = p;
251 *keyp = key;
252 if (valp)
253 *valp = val;
254
255 return 1;
256}
257
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269
270
271static int cuse_parse_devinfo(char *p, size_t len, struct cuse_devinfo *devinfo)
272{
273 char *end = p + len;
274 char *key, *val;
275 int rc;
276
277 while (true) {
278 rc = cuse_parse_one(&p, end, &key, &val);
279 if (rc < 0)
280 return rc;
281 if (!rc)
282 break;
283 if (strcmp(key, "DEVNAME") == 0)
284 devinfo->name = val;
285 else
286 pr_warn("unknown device info \"%s\"\n", key);
287 }
288
289 if (!devinfo->name || !strlen(devinfo->name)) {
290 pr_err("DEVNAME unspecified\n");
291 return -EINVAL;
292 }
293
294 return 0;
295}
296
297static void cuse_gendev_release(struct device *dev)
298{
299 kfree(dev);
300}
301
302struct cuse_init_args {
303 struct fuse_args_pages ap;
304 struct cuse_init_in in;
305 struct cuse_init_out out;
306 struct page *page;
307 struct fuse_page_desc desc;
308};
309
310
311
312
313
314
315
316
317static void cuse_process_init_reply(struct fuse_mount *fm,
318 struct fuse_args *args, int error)
319{
320 struct fuse_conn *fc = fm->fc;
321 struct cuse_init_args *ia = container_of(args, typeof(*ia), ap.args);
322 struct fuse_args_pages *ap = &ia->ap;
323 struct cuse_conn *cc = fc_to_cc(fc), *pos;
324 struct cuse_init_out *arg = &ia->out;
325 struct page *page = ap->pages[0];
326 struct cuse_devinfo devinfo = { };
327 struct device *dev;
328 struct cdev *cdev;
329 dev_t devt;
330 int rc, i;
331
332 if (error || arg->major != FUSE_KERNEL_VERSION || arg->minor < 11)
333 goto err;
334
335 fc->minor = arg->minor;
336 fc->max_read = max_t(unsigned, arg->max_read, 4096);
337 fc->max_write = max_t(unsigned, arg->max_write, 4096);
338
339
340 cc->unrestricted_ioctl = arg->flags & CUSE_UNRESTRICTED_IOCTL;
341
342 rc = cuse_parse_devinfo(page_address(page), ap->args.out_args[1].size,
343 &devinfo);
344 if (rc)
345 goto err;
346
347
348 devt = MKDEV(arg->dev_major, arg->dev_minor);
349 if (!MAJOR(devt))
350 rc = alloc_chrdev_region(&devt, MINOR(devt), 1, devinfo.name);
351 else
352 rc = register_chrdev_region(devt, 1, devinfo.name);
353 if (rc) {
354 pr_err("failed to register chrdev region\n");
355 goto err;
356 }
357
358
359 rc = -ENOMEM;
360 dev = kzalloc(sizeof(*dev), GFP_KERNEL);
361 if (!dev)
362 goto err_region;
363
364 device_initialize(dev);
365 dev_set_uevent_suppress(dev, 1);
366 dev->class = cuse_class;
367 dev->devt = devt;
368 dev->release = cuse_gendev_release;
369 dev_set_drvdata(dev, cc);
370 dev_set_name(dev, "%s", devinfo.name);
371
372 mutex_lock(&cuse_lock);
373
374
375 for (i = 0; i < CUSE_CONNTBL_LEN; ++i) {
376 list_for_each_entry(pos, &cuse_conntbl[i], list)
377 if (!strcmp(dev_name(pos->dev), dev_name(dev)))
378 goto err_unlock;
379 }
380
381 rc = device_add(dev);
382 if (rc)
383 goto err_unlock;
384
385
386 rc = -ENOMEM;
387 cdev = cdev_alloc();
388 if (!cdev)
389 goto err_unlock;
390
391 cdev->owner = THIS_MODULE;
392 cdev->ops = &cuse_frontend_fops;
393
394 rc = cdev_add(cdev, devt, 1);
395 if (rc)
396 goto err_cdev;
397
398 cc->dev = dev;
399 cc->cdev = cdev;
400
401
402 list_add(&cc->list, cuse_conntbl_head(devt));
403 mutex_unlock(&cuse_lock);
404
405
406 dev_set_uevent_suppress(dev, 0);
407 kobject_uevent(&dev->kobj, KOBJ_ADD);
408out:
409 kfree(ia);
410 __free_page(page);
411 return;
412
413err_cdev:
414 cdev_del(cdev);
415err_unlock:
416 mutex_unlock(&cuse_lock);
417 put_device(dev);
418err_region:
419 unregister_chrdev_region(devt, 1);
420err:
421 fuse_abort_conn(fc);
422 goto out;
423}
424
425static int cuse_send_init(struct cuse_conn *cc)
426{
427 int rc;
428 struct page *page;
429 struct fuse_mount *fm = &cc->fm;
430 struct cuse_init_args *ia;
431 struct fuse_args_pages *ap;
432
433 BUILD_BUG_ON(CUSE_INIT_INFO_MAX > PAGE_SIZE);
434
435 rc = -ENOMEM;
436 page = alloc_page(GFP_KERNEL | __GFP_ZERO);
437 if (!page)
438 goto err;
439
440 ia = kzalloc(sizeof(*ia), GFP_KERNEL);
441 if (!ia)
442 goto err_free_page;
443
444 ap = &ia->ap;
445 ia->in.major = FUSE_KERNEL_VERSION;
446 ia->in.minor = FUSE_KERNEL_MINOR_VERSION;
447 ia->in.flags |= CUSE_UNRESTRICTED_IOCTL;
448 ap->args.opcode = CUSE_INIT;
449 ap->args.in_numargs = 1;
450 ap->args.in_args[0].size = sizeof(ia->in);
451 ap->args.in_args[0].value = &ia->in;
452 ap->args.out_numargs = 2;
453 ap->args.out_args[0].size = sizeof(ia->out);
454 ap->args.out_args[0].value = &ia->out;
455 ap->args.out_args[1].size = CUSE_INIT_INFO_MAX;
456 ap->args.out_argvar = true;
457 ap->args.out_pages = true;
458 ap->num_pages = 1;
459 ap->pages = &ia->page;
460 ap->descs = &ia->desc;
461 ia->page = page;
462 ia->desc.length = ap->args.out_args[1].size;
463 ap->args.end = cuse_process_init_reply;
464
465 rc = fuse_simple_background(fm, &ap->args, GFP_KERNEL);
466 if (rc) {
467 kfree(ia);
468err_free_page:
469 __free_page(page);
470 }
471err:
472 return rc;
473}
474
475static void cuse_fc_release(struct fuse_conn *fc)
476{
477 struct cuse_conn *cc = fc_to_cc(fc);
478 kfree_rcu(cc, fc.rcu);
479}
480
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494
495
496static int cuse_channel_open(struct inode *inode, struct file *file)
497{
498 struct fuse_dev *fud;
499 struct cuse_conn *cc;
500 int rc;
501
502
503 cc = kzalloc(sizeof(*cc), GFP_KERNEL);
504 if (!cc)
505 return -ENOMEM;
506
507
508
509
510
511 fuse_conn_init(&cc->fc, &cc->fm, file->f_cred->user_ns,
512 &fuse_dev_fiq_ops, NULL);
513
514 cc->fc.release = cuse_fc_release;
515 fud = fuse_dev_alloc_install(&cc->fc);
516 fuse_conn_put(&cc->fc);
517 if (!fud)
518 return -ENOMEM;
519
520 INIT_LIST_HEAD(&cc->list);
521
522 cc->fc.initialized = 1;
523 rc = cuse_send_init(cc);
524 if (rc) {
525 fuse_dev_free(fud);
526 return rc;
527 }
528 file->private_data = fud;
529
530 return 0;
531}
532
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541
542
543
544static int cuse_channel_release(struct inode *inode, struct file *file)
545{
546 struct fuse_dev *fud = file->private_data;
547 struct cuse_conn *cc = fc_to_cc(fud->fc);
548 int rc;
549
550
551 mutex_lock(&cuse_lock);
552 list_del_init(&cc->list);
553 mutex_unlock(&cuse_lock);
554
555
556 if (cc->dev)
557 device_unregister(cc->dev);
558 if (cc->cdev) {
559 unregister_chrdev_region(cc->cdev->dev, 1);
560 cdev_del(cc->cdev);
561 }
562
563 rc = fuse_dev_release(inode, file);
564
565 return rc;
566}
567
568static struct file_operations cuse_channel_fops;
569
570
571
572
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574
575
576
577static ssize_t cuse_class_waiting_show(struct device *dev,
578 struct device_attribute *attr, char *buf)
579{
580 struct cuse_conn *cc = dev_get_drvdata(dev);
581
582 return sprintf(buf, "%d\n", atomic_read(&cc->fc.num_waiting));
583}
584static DEVICE_ATTR(waiting, 0400, cuse_class_waiting_show, NULL);
585
586static ssize_t cuse_class_abort_store(struct device *dev,
587 struct device_attribute *attr,
588 const char *buf, size_t count)
589{
590 struct cuse_conn *cc = dev_get_drvdata(dev);
591
592 fuse_abort_conn(&cc->fc);
593 return count;
594}
595static DEVICE_ATTR(abort, 0200, NULL, cuse_class_abort_store);
596
597static struct attribute *cuse_class_dev_attrs[] = {
598 &dev_attr_waiting.attr,
599 &dev_attr_abort.attr,
600 NULL,
601};
602ATTRIBUTE_GROUPS(cuse_class_dev);
603
604static struct miscdevice cuse_miscdev = {
605 .minor = CUSE_MINOR,
606 .name = "cuse",
607 .fops = &cuse_channel_fops,
608};
609
610MODULE_ALIAS_MISCDEV(CUSE_MINOR);
611MODULE_ALIAS("devname:cuse");
612
613static int __init cuse_init(void)
614{
615 int i, rc;
616
617
618 for (i = 0; i < CUSE_CONNTBL_LEN; i++)
619 INIT_LIST_HEAD(&cuse_conntbl[i]);
620
621
622 cuse_channel_fops = fuse_dev_operations;
623 cuse_channel_fops.owner = THIS_MODULE;
624 cuse_channel_fops.open = cuse_channel_open;
625 cuse_channel_fops.release = cuse_channel_release;
626
627 cuse_channel_fops.unlocked_ioctl = NULL;
628
629 cuse_class = class_create(THIS_MODULE, "cuse");
630 if (IS_ERR(cuse_class))
631 return PTR_ERR(cuse_class);
632
633 cuse_class->dev_groups = cuse_class_dev_groups;
634
635 rc = misc_register(&cuse_miscdev);
636 if (rc) {
637 class_destroy(cuse_class);
638 return rc;
639 }
640
641 return 0;
642}
643
644static void __exit cuse_exit(void)
645{
646 misc_deregister(&cuse_miscdev);
647 class_destroy(cuse_class);
648}
649
650module_init(cuse_init);
651module_exit(cuse_exit);
652
653MODULE_AUTHOR("Tejun Heo <tj@kernel.org>");
654MODULE_DESCRIPTION("Character device in Userspace");
655MODULE_LICENSE("GPL");
656