projects/linux·blob v3.17 · refs

1929 lines · 47.2 KiB

1/*
2 * linux/drivers/block/loop.c
3 *
4 * Written by Theodore Ts'o, 3/29/93
5 *
6 * Copyright 1993 by Theodore Ts'o. Redistribution of this file is
7 * permitted under the GNU General Public License.
8 *
9 * DES encryption plus some minor changes by Werner Almesberger, 30-MAY-1993
10 * more DES encryption plus IDEA encryption by Nicholas J. Leon, June 20, 1996
11 *
12 * Modularized and updated for 1.1.16 kernel - Mitch Dsouza 28th May 1994
13 * Adapted for 1.3.59 kernel - Andries Brouwer, 1 Feb 1996
14 *
15 * Fixed do_loop_request() re-entrancy - [email protected] Mar 20, 1997
16 *
17 * Added devfs support - Richard Gooch <[email protected]> 16-Jan-1998
18 *
19 * Handle sparse backing files correctly - Kenn Humborg, Jun 28, 1998
20 *
21 * Loadable modules and other fixes by AK, 1998
22 *
23 * Make real block number available to downstream transfer functions, enables
24 * CBC (and relatives) mode encryption requiring unique IVs per data block.
25 * Reed H. Petty, [email protected]
26 *
27 * Maximum number of loop devices now dynamic via max_loop module parameter.
28 * Russell Kroll <[email protected]> 19990701
29 *
30 * Maximum number of loop devices when compiled-in now selectable by passing
31 * max_loop=<1-255> to the kernel on boot.
32 * Erik I. Bolsø, <[email protected]>, Oct 31, 1999
33 *
34 * Completely rewrite request handling to be make_request_fn style and
35 * non blocking, pushing work to a helper thread. Lots of fixes from
36 * Al Viro too.
37 * Jens Axboe <[email protected]>, Nov 2000
38 *
39 * Support up to 256 loop devices
40 * Heinz Mauelshagen <[email protected]>, Feb 2002
41 *
42 * Support for falling back on the write file operation when the address space
43 * operations write_begin is not available on the backing filesystem.
44 * Anton Altaparmakov, 16 Feb 2005
45 *
46 * Still To Fix:
47 * - Advisory locking is ignored here.
48 * - Should use an own CAP_* category instead of CAP_SYS_ADMIN
49 *
50 */
51
52#include <linux/module.h>
53#include <linux/moduleparam.h>
54#include <linux/sched.h>
55#include <linux/fs.h>
56#include <linux/file.h>
57#include <linux/stat.h>
58#include <linux/errno.h>
59#include <linux/major.h>
60#include <linux/wait.h>
61#include <linux/blkdev.h>
62#include <linux/blkpg.h>
63#include <linux/init.h>
64#include <linux/swap.h>
65#include <linux/slab.h>
66#include <linux/compat.h>
67#include <linux/suspend.h>
68#include <linux/freezer.h>
69#include <linux/mutex.h>
70#include <linux/writeback.h>
71#include <linux/completion.h>
72#include <linux/highmem.h>
73#include <linux/kthread.h>
74#include <linux/splice.h>
75#include <linux/sysfs.h>
76#include <linux/miscdevice.h>
77#include <linux/falloc.h>
78#include "loop.h"
79
80#include <asm/uaccess.h>
81
82static DEFINE_IDR(loop_index_idr);
83static DEFINE_MUTEX(loop_index_mutex);
84
85static int max_part;
86static int part_shift;
87
88/*
89 * Transfer functions
90 */
91static int transfer_none(struct loop_device *lo, int cmd,
92 struct page *raw_page, unsigned raw_off,
93 struct page *loop_page, unsigned loop_off,
94 int size, sector_t real_block)
95{
96 char *raw_buf = kmap_atomic(raw_page) + raw_off;
97 char *loop_buf = kmap_atomic(loop_page) + loop_off;
98
99 if (cmd == READ)
100 memcpy(loop_buf, raw_buf, size);
101 else
102 memcpy(raw_buf, loop_buf, size);
103
104 kunmap_atomic(loop_buf);
105 kunmap_atomic(raw_buf);
106 cond_resched();
107 return 0;
108}
109
110static int transfer_xor(struct loop_device *lo, int cmd,
111 struct page *raw_page, unsigned raw_off,
112 struct page *loop_page, unsigned loop_off,
113 int size, sector_t real_block)
114{
115 char *raw_buf = kmap_atomic(raw_page) + raw_off;
116 char *loop_buf = kmap_atomic(loop_page) + loop_off;
117 char *in, *out, *key;
118 int i, keysize;
119
120 if (cmd == READ) {
121 in = raw_buf;
122 out = loop_buf;
123 } else {
124 in = loop_buf;
125 out = raw_buf;
126 }
127
128 key = lo->lo_encrypt_key;
129 keysize = lo->lo_encrypt_key_size;
130 for (i = 0; i < size; i++)
131 *out++ = *in++ ^ key[(i & 511) % keysize];
132
133 kunmap_atomic(loop_buf);
134 kunmap_atomic(raw_buf);
135 cond_resched();
136 return 0;
137}
138
139static int xor_init(struct loop_device *lo, const struct loop_info64 *info)
140{
141 if (unlikely(info->lo_encrypt_key_size <= 0))
142 return -EINVAL;
143 return 0;
144}
145
146static struct loop_func_table none_funcs = {
147 .number = LO_CRYPT_NONE,
148 .transfer = transfer_none,
149};
150
151static struct loop_func_table xor_funcs = {
152 .number = LO_CRYPT_XOR,
153 .transfer = transfer_xor,
154 .init = xor_init
155};
156
157/* xfer_funcs[0] is special - its release function is never called */
158static struct loop_func_table *xfer_funcs[MAX_LO_CRYPT] = {
159 &none_funcs,
160 &xor_funcs
161};
162
163static loff_t get_size(loff_t offset, loff_t sizelimit, struct file *file)
164{
165 loff_t loopsize;
166
167 /* Compute loopsize in bytes */
168 loopsize = i_size_read(file->f_mapping->host);
169 if (offset > 0)
170 loopsize -= offset;
171 /* offset is beyond i_size, weird but possible */
172 if (loopsize < 0)
173 return 0;
174
175 if (sizelimit > 0 && sizelimit < loopsize)
176 loopsize = sizelimit;
177 /*
178 * Unfortunately, if we want to do I/O on the device,
179 * the number of 512-byte sectors has to fit into a sector_t.
180 */
181 return loopsize >> 9;
182}
183
184static loff_t get_loop_size(struct loop_device *lo, struct file *file)
185{
186 return get_size(lo->lo_offset, lo->lo_sizelimit, file);
187}
188
189static int
190figure_loop_size(struct loop_device *lo, loff_t offset, loff_t sizelimit)
191{
192 loff_t size = get_size(offset, sizelimit, lo->lo_backing_file);
193 sector_t x = (sector_t)size;
194 struct block_device *bdev = lo->lo_device;
195
196 if (unlikely((loff_t)x != size))
197 return -EFBIG;
198 if (lo->lo_offset != offset)
199 lo->lo_offset = offset;
200 if (lo->lo_sizelimit != sizelimit)
201 lo->lo_sizelimit = sizelimit;
202 set_capacity(lo->lo_disk, x);
203 bd_set_size(bdev, (loff_t)get_capacity(bdev->bd_disk) << 9);
204 /* let user-space know about the new size */
205 kobject_uevent(&disk_to_dev(bdev->bd_disk)->kobj, KOBJ_CHANGE);
206 return 0;
207}
208
209static inline int
210lo_do_transfer(struct loop_device *lo, int cmd,
211 struct page *rpage, unsigned roffs,
212 struct page *lpage, unsigned loffs,
213 int size, sector_t rblock)
214{
215 if (unlikely(!lo->transfer))
216 return 0;
217
218 return lo->transfer(lo, cmd, rpage, roffs, lpage, loffs, size, rblock);
219}
220
221/**
222 * __do_lo_send_write - helper for writing data to a loop device
223 *
224 * This helper just factors out common code between do_lo_send_direct_write()
225 * and do_lo_send_write().
226 */
227static int __do_lo_send_write(struct file *file,
228 u8 *buf, const int len, loff_t pos)
229{
230 ssize_t bw;
231 mm_segment_t old_fs = get_fs();
232
233 file_start_write(file);
234 set_fs(get_ds());
235 bw = file->f_op->write(file, buf, len, &pos);
236 set_fs(old_fs);
237 file_end_write(file);
238 if (likely(bw == len))
239 return 0;
240 printk_ratelimited(KERN_ERR "loop: Write error at byte offset %llu, length %i.\n",
241 (unsigned long long)pos, len);
242 if (bw >= 0)
243 bw = -EIO;
244 return bw;
245}
246
247/**
248 * do_lo_send_direct_write - helper for writing data to a loop device
249 *
250 * This is the fast, non-transforming version that does not need double
251 * buffering.
252 */
253static int do_lo_send_direct_write(struct loop_device *lo,
254 struct bio_vec *bvec, loff_t pos, struct page *page)
255{
256 ssize_t bw = __do_lo_send_write(lo->lo_backing_file,
257 kmap(bvec->bv_page) + bvec->bv_offset,
258 bvec->bv_len, pos);
259 kunmap(bvec->bv_page);
260 cond_resched();
261 return bw;
262}
263
264/**
265 * do_lo_send_write - helper for writing data to a loop device
266 *
267 * This is the slow, transforming version that needs to double buffer the
268 * data as it cannot do the transformations in place without having direct
269 * access to the destination pages of the backing file.
270 */
271static int do_lo_send_write(struct loop_device *lo, struct bio_vec *bvec,
272 loff_t pos, struct page *page)
273{
274 int ret = lo_do_transfer(lo, WRITE, page, 0, bvec->bv_page,
275 bvec->bv_offset, bvec->bv_len, pos >> 9);
276 if (likely(!ret))
277 return __do_lo_send_write(lo->lo_backing_file,
278 page_address(page), bvec->bv_len,
279 pos);
280 printk_ratelimited(KERN_ERR "loop: Transfer error at byte offset %llu, "
281 "length %i.\n", (unsigned long long)pos, bvec->bv_len);
282 if (ret > 0)
283 ret = -EIO;
284 return ret;
285}
286
287static int lo_send(struct loop_device *lo, struct bio *bio, loff_t pos)
288{
289 int (*do_lo_send)(struct loop_device *, struct bio_vec *, loff_t,
290 struct page *page);
291 struct bio_vec bvec;
292 struct bvec_iter iter;
293 struct page *page = NULL;
294 int ret = 0;
295
296 if (lo->transfer != transfer_none) {
297 page = alloc_page(GFP_NOIO | __GFP_HIGHMEM);
298 if (unlikely(!page))
299 goto fail;
300 kmap(page);
301 do_lo_send = do_lo_send_write;
302 } else {
303 do_lo_send = do_lo_send_direct_write;
304 }
305
306 bio_for_each_segment(bvec, bio, iter) {
307 ret = do_lo_send(lo, &bvec, pos, page);
308 if (ret < 0)
309 break;
310 pos += bvec.bv_len;
311 }
312 if (page) {
313 kunmap(page);
314 __free_page(page);
315 }
316out:
317 return ret;
318fail:
319 printk_ratelimited(KERN_ERR "loop: Failed to allocate temporary page for write.\n");
320 ret = -ENOMEM;
321 goto out;
322}
323
324struct lo_read_data {
325 struct loop_device *lo;
326 struct page *page;
327 unsigned offset;
328 int bsize;
329};
330
331static int
332lo_splice_actor(struct pipe_inode_info *pipe, struct pipe_buffer *buf,
333 struct splice_desc *sd)
334{
335 struct lo_read_data *p = sd->u.data;
336 struct loop_device *lo = p->lo;
337 struct page *page = buf->page;
338 sector_t IV;
339 int size;
340
341 IV = ((sector_t) page->index << (PAGE_CACHE_SHIFT - 9)) +
342 (buf->offset >> 9);
343 size = sd->len;
344 if (size > p->bsize)
345 size = p->bsize;
346
347 if (lo_do_transfer(lo, READ, page, buf->offset, p->page, p->offset, size, IV)) {
348 printk_ratelimited(KERN_ERR "loop: transfer error block %ld\n",
349 page->index);
350 size = -EINVAL;
351 }
352
353 flush_dcache_page(p->page);
354
355 if (size > 0)
356 p->offset += size;
357
358 return size;
359}
360
361static int
362lo_direct_splice_actor(struct pipe_inode_info *pipe, struct splice_desc *sd)
363{
364 return __splice_from_pipe(pipe, sd, lo_splice_actor);
365}
366
367static ssize_t
368do_lo_receive(struct loop_device *lo,
369 struct bio_vec *bvec, int bsize, loff_t pos)
370{
371 struct lo_read_data cookie;
372 struct splice_desc sd;
373 struct file *file;
374 ssize_t retval;
375
376 cookie.lo = lo;
377 cookie.page = bvec->bv_page;
378 cookie.offset = bvec->bv_offset;
379 cookie.bsize = bsize;
380
381 sd.len = 0;
382 sd.total_len = bvec->bv_len;
383 sd.flags = 0;
384 sd.pos = pos;
385 sd.u.data = &cookie;
386
387 file = lo->lo_backing_file;
388 retval = splice_direct_to_actor(file, &sd, lo_direct_splice_actor);
389
390 return retval;
391}
392
393static int
394lo_receive(struct loop_device *lo, struct bio *bio, int bsize, loff_t pos)
395{
396 struct bio_vec bvec;
397 struct bvec_iter iter;
398 ssize_t s;
399
400 bio_for_each_segment(bvec, bio, iter) {
401 s = do_lo_receive(lo, &bvec, bsize, pos);
402 if (s < 0)
403 return s;
404
405 if (s != bvec.bv_len) {
406 zero_fill_bio(bio);
407 break;
408 }
409 pos += bvec.bv_len;
410 }
411 return 0;
412}
413
414static int do_bio_filebacked(struct loop_device *lo, struct bio *bio)
415{
416 loff_t pos;
417 int ret;
418
419 pos = ((loff_t) bio->bi_iter.bi_sector << 9) + lo->lo_offset;
420
421 if (bio_rw(bio) == WRITE) {
422 struct file *file = lo->lo_backing_file;
423
424 if (bio->bi_rw & REQ_FLUSH) {
425 ret = vfs_fsync(file, 0);
426 if (unlikely(ret && ret != -EINVAL)) {
427 ret = -EIO;
428 goto out;
429 }
430 }
431
432 /*
433 * We use punch hole to reclaim the free space used by the
434 * image a.k.a. discard. However we do not support discard if
435 * encryption is enabled, because it may give an attacker
436 * useful information.
437 */
438 if (bio->bi_rw & REQ_DISCARD) {
439 struct file *file = lo->lo_backing_file;
440 int mode = FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE;
441
442 if ((!file->f_op->fallocate) ||
443 lo->lo_encrypt_key_size) {
444 ret = -EOPNOTSUPP;
445 goto out;
446 }
447 ret = file->f_op->fallocate(file, mode, pos,
448 bio->bi_iter.bi_size);
449 if (unlikely(ret && ret != -EINVAL &&
450 ret != -EOPNOTSUPP))
451 ret = -EIO;
452 goto out;
453 }
454
455 ret = lo_send(lo, bio, pos);
456
457 if ((bio->bi_rw & REQ_FUA) && !ret) {
458 ret = vfs_fsync(file, 0);
459 if (unlikely(ret && ret != -EINVAL))
460 ret = -EIO;
461 }
462 } else
463 ret = lo_receive(lo, bio, lo->lo_blocksize, pos);
464
465out:
466 return ret;
467}
468
469/*
470 * Add bio to back of pending list
471 */
472static void loop_add_bio(struct loop_device *lo, struct bio *bio)
473{
474 lo->lo_bio_count++;
475 bio_list_add(&lo->lo_bio_list, bio);
476}
477
478/*
479 * Grab first pending buffer
480 */
481static struct bio *loop_get_bio(struct loop_device *lo)
482{
483 lo->lo_bio_count--;
484 return bio_list_pop(&lo->lo_bio_list);
485}
486
487static void loop_make_request(struct request_queue *q, struct bio *old_bio)
488{
489 struct loop_device *lo = q->queuedata;
490 int rw = bio_rw(old_bio);
491
492 if (rw == READA)
493 rw = READ;
494
495 BUG_ON(!lo || (rw != READ && rw != WRITE));
496
497 spin_lock_irq(&lo->lo_lock);
498 if (lo->lo_state != Lo_bound)
499 goto out;
500 if (unlikely(rw == WRITE && (lo->lo_flags & LO_FLAGS_READ_ONLY)))
501 goto out;
502 if (lo->lo_bio_count >= q->nr_congestion_on)
503 wait_event_lock_irq(lo->lo_req_wait,
504 lo->lo_bio_count < q->nr_congestion_off,
505 lo->lo_lock);
506 loop_add_bio(lo, old_bio);
507 wake_up(&lo->lo_event);
508 spin_unlock_irq(&lo->lo_lock);
509 return;
510
511out:
512 spin_unlock_irq(&lo->lo_lock);
513 bio_io_error(old_bio);
514}
515
516struct switch_request {
517 struct file *file;
518 struct completion wait;
519};
520
521static void do_loop_switch(struct loop_device *, struct switch_request *);
522
523static inline void loop_handle_bio(struct loop_device *lo, struct bio *bio)
524{
525 if (unlikely(!bio->bi_bdev)) {
526 do_loop_switch(lo, bio->bi_private);
527 bio_put(bio);
528 } else {
529 int ret = do_bio_filebacked(lo, bio);
530 bio_endio(bio, ret);
531 }
532}
533
534/*
535 * worker thread that handles reads/writes to file backed loop devices,
536 * to avoid blocking in our make_request_fn. it also does loop decrypting
537 * on reads for block backed loop, as that is too heavy to do from
538 * b_end_io context where irqs may be disabled.
539 *
540 * Loop explanation: loop_clr_fd() sets lo_state to Lo_rundown before
541 * calling kthread_stop(). Therefore once kthread_should_stop() is
542 * true, make_request will not place any more requests. Therefore
543 * once kthread_should_stop() is true and lo_bio is NULL, we are
544 * done with the loop.
545 */
546static int loop_thread(void *data)
547{
548 struct loop_device *lo = data;
549 struct bio *bio;
550
551 set_user_nice(current, MIN_NICE);
552
553 while (!kthread_should_stop() || !bio_list_empty(&lo->lo_bio_list)) {
554
555 wait_event_interruptible(lo->lo_event,
556 !bio_list_empty(&lo->lo_bio_list) ||
557 kthread_should_stop());
558
559 if (bio_list_empty(&lo->lo_bio_list))
560 continue;
561 spin_lock_irq(&lo->lo_lock);
562 bio = loop_get_bio(lo);
563 if (lo->lo_bio_count < lo->lo_queue->nr_congestion_off)
564 wake_up(&lo->lo_req_wait);
565 spin_unlock_irq(&lo->lo_lock);
566
567 BUG_ON(!bio);
568 loop_handle_bio(lo, bio);
569 }
570
571 return 0;
572}
573
574/*
575 * loop_switch performs the hard work of switching a backing store.
576 * First it needs to flush existing IO, it does this by sending a magic
577 * BIO down the pipe. The completion of this BIO does the actual switch.
578 */
579static int loop_switch(struct loop_device *lo, struct file *file)
580{
581 struct switch_request w;
582 struct bio *bio = bio_alloc(GFP_KERNEL, 0);
583 if (!bio)
584 return -ENOMEM;
585 init_completion(&w.wait);
586 w.file = file;
587 bio->bi_private = &w;
588 bio->bi_bdev = NULL;
589 loop_make_request(lo->lo_queue, bio);
590 wait_for_completion(&w.wait);
591 return 0;
592}
593
594/*
595 * Helper to flush the IOs in loop, but keeping loop thread running
596 */
597static int loop_flush(struct loop_device *lo)
598{
599 /* loop not yet configured, no running thread, nothing to flush */
600 if (!lo->lo_thread)
601 return 0;
602
603 return loop_switch(lo, NULL);
604}
605
606/*
607 * Do the actual switch; called from the BIO completion routine
608 */
609static void do_loop_switch(struct loop_device *lo, struct switch_request *p)
610{
611 struct file *file = p->file;
612 struct file *old_file = lo->lo_backing_file;
613 struct address_space *mapping;
614
615 /* if no new file, only flush of queued bios requested */
616 if (!file)
617 goto out;
618
619 mapping = file->f_mapping;
620 mapping_set_gfp_mask(old_file->f_mapping, lo->old_gfp_mask);
621 lo->lo_backing_file = file;
622 lo->lo_blocksize = S_ISBLK(mapping->host->i_mode) ?
623 mapping->host->i_bdev->bd_block_size : PAGE_SIZE;
624 lo->old_gfp_mask = mapping_gfp_mask(mapping);
625 mapping_set_gfp_mask(mapping, lo->old_gfp_mask & ~(__GFP_IO|__GFP_FS));
626out:
627 complete(&p->wait);
628}
629
630
631/*
632 * loop_change_fd switched the backing store of a loopback device to
633 * a new file. This is useful for operating system installers to free up
634 * the original file and in High Availability environments to switch to
635 * an alternative location for the content in case of server meltdown.
636 * This can only work if the loop device is used read-only, and if the
637 * new backing store is the same size and type as the old backing store.
638 */
639static int loop_change_fd(struct loop_device *lo, struct block_device *bdev,
640 unsigned int arg)
641{
642 struct file *file, *old_file;
643 struct inode *inode;
644 int error;
645
646 error = -ENXIO;
647 if (lo->lo_state != Lo_bound)
648 goto out;
649
650 /* the loop device has to be read-only */
651 error = -EINVAL;
652 if (!(lo->lo_flags & LO_FLAGS_READ_ONLY))
653 goto out;
654
655 error = -EBADF;
656 file = fget(arg);
657 if (!file)
658 goto out;
659
660 inode = file->f_mapping->host;
661 old_file = lo->lo_backing_file;
662
663 error = -EINVAL;
664
665 if (!S_ISREG(inode->i_mode) && !S_ISBLK(inode->i_mode))
666 goto out_putf;
667
668 /* size of the new backing store needs to be the same */
669 if (get_loop_size(lo, file) != get_loop_size(lo, old_file))
670 goto out_putf;
671
672 /* and ... switch */
673 error = loop_switch(lo, file);
674 if (error)
675 goto out_putf;
676
677 fput(old_file);
678 if (lo->lo_flags & LO_FLAGS_PARTSCAN)
679 ioctl_by_bdev(bdev, BLKRRPART, 0);
680 return 0;
681
682 out_putf:
683 fput(file);
684 out:
685 return error;
686}
687
688static inline int is_loop_device(struct file *file)
689{
690 struct inode *i = file->f_mapping->host;
691
692 return i && S_ISBLK(i->i_mode) && MAJOR(i->i_rdev) == LOOP_MAJOR;
693}
694
695/* loop sysfs attributes */
696
697static ssize_t loop_attr_show(struct device *dev, char *page,
698 ssize_t (*callback)(struct loop_device *, char *))
699{
700 struct gendisk *disk = dev_to_disk(dev);
701 struct loop_device *lo = disk->private_data;
702
703 return callback(lo, page);
704}
705
706#define LOOP_ATTR_RO(_name) \
707static ssize_t loop_attr_##_name##_show(struct loop_device *, char *); \
708static ssize_t loop_attr_do_show_##_name(struct device *d, \
709 struct device_attribute *attr, char *b) \
710{ \
711 return loop_attr_show(d, b, loop_attr_##_name##_show); \
712} \
713static struct device_attribute loop_attr_##_name = \
714 __ATTR(_name, S_IRUGO, loop_attr_do_show_##_name, NULL);
715
716static ssize_t loop_attr_backing_file_show(struct loop_device *lo, char *buf)
717{
718 ssize_t ret;
719 char *p = NULL;
720
721 spin_lock_irq(&lo->lo_lock);
722 if (lo->lo_backing_file)
723 p = d_path(&lo->lo_backing_file->f_path, buf, PAGE_SIZE - 1);
724 spin_unlock_irq(&lo->lo_lock);
725
726 if (IS_ERR_OR_NULL(p))
727 ret = PTR_ERR(p);
728 else {
729 ret = strlen(p);
730 memmove(buf, p, ret);
731 buf[ret++] = '\n';
732 buf[ret] = 0;
733 }
734
735 return ret;
736}
737
738static ssize_t loop_attr_offset_show(struct loop_device *lo, char *buf)
739{
740 return sprintf(buf, "%llu\n", (unsigned long long)lo->lo_offset);
741}
742
743static ssize_t loop_attr_sizelimit_show(struct loop_device *lo, char *buf)
744{
745 return sprintf(buf, "%llu\n", (unsigned long long)lo->lo_sizelimit);
746}
747
748static ssize_t loop_attr_autoclear_show(struct loop_device *lo, char *buf)
749{
750 int autoclear = (lo->lo_flags & LO_FLAGS_AUTOCLEAR);
751
752 return sprintf(buf, "%s\n", autoclear ? "1" : "0");
753}
754
755static ssize_t loop_attr_partscan_show(struct loop_device *lo, char *buf)
756{
757 int partscan = (lo->lo_flags & LO_FLAGS_PARTSCAN);
758
759 return sprintf(buf, "%s\n", partscan ? "1" : "0");
760}
761
762LOOP_ATTR_RO(backing_file);
763LOOP_ATTR_RO(offset);
764LOOP_ATTR_RO(sizelimit);
765LOOP_ATTR_RO(autoclear);
766LOOP_ATTR_RO(partscan);
767
768static struct attribute *loop_attrs[] = {
769 &loop_attr_backing_file.attr,
770 &loop_attr_offset.attr,
771 &loop_attr_sizelimit.attr,
772 &loop_attr_autoclear.attr,
773 &loop_attr_partscan.attr,
774 NULL,
775};
776
777static struct attribute_group loop_attribute_group = {
778 .name = "loop",
779 .attrs= loop_attrs,
780};
781
782static int loop_sysfs_init(struct loop_device *lo)
783{
784 return sysfs_create_group(&disk_to_dev(lo->lo_disk)->kobj,
785 &loop_attribute_group);
786}
787
788static void loop_sysfs_exit(struct loop_device *lo)
789{
790 sysfs_remove_group(&disk_to_dev(lo->lo_disk)->kobj,
791 &loop_attribute_group);
792}
793
794static void loop_config_discard(struct loop_device *lo)
795{
796 struct file *file = lo->lo_backing_file;
797 struct inode *inode = file->f_mapping->host;
798 struct request_queue *q = lo->lo_queue;
799
800 /*
801 * We use punch hole to reclaim the free space used by the
802 * image a.k.a. discard. However we do not support discard if
803 * encryption is enabled, because it may give an attacker
804 * useful information.
805 */
806 if ((!file->f_op->fallocate) ||
807 lo->lo_encrypt_key_size) {
808 q->limits.discard_granularity = 0;
809 q->limits.discard_alignment = 0;
810 q->limits.max_discard_sectors = 0;
811 q->limits.discard_zeroes_data = 0;
812 queue_flag_clear_unlocked(QUEUE_FLAG_DISCARD, q);
813 return;
814 }
815
816 q->limits.discard_granularity = inode->i_sb->s_blocksize;
817 q->limits.discard_alignment = 0;
818 q->limits.max_discard_sectors = UINT_MAX >> 9;
819 q->limits.discard_zeroes_data = 1;
820 queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, q);
821}
822
823static int loop_set_fd(struct loop_device *lo, fmode_t mode,
824 struct block_device *bdev, unsigned int arg)
825{
826 struct file *file, *f;
827 struct inode *inode;
828 struct address_space *mapping;
829 unsigned lo_blocksize;
830 int lo_flags = 0;
831 int error;
832 loff_t size;
833
834 /* This is safe, since we have a reference from open(). */
835 __module_get(THIS_MODULE);
836
837 error = -EBADF;
838 file = fget(arg);
839 if (!file)
840 goto out;
841
842 error = -EBUSY;
843 if (lo->lo_state != Lo_unbound)
844 goto out_putf;
845
846 /* Avoid recursion */
847 f = file;
848 while (is_loop_device(f)) {
849 struct loop_device *l;
850
851 if (f->f_mapping->host->i_bdev == bdev)
852 goto out_putf;
853
854 l = f->f_mapping->host->i_bdev->bd_disk->private_data;
855 if (l->lo_state == Lo_unbound) {
856 error = -EINVAL;
857 goto out_putf;
858 }
859 f = l->lo_backing_file;
860 }
861
862 mapping = file->f_mapping;
863 inode = mapping->host;
864
865 error = -EINVAL;
866 if (!S_ISREG(inode->i_mode) && !S_ISBLK(inode->i_mode))
867 goto out_putf;
868
869 if (!(file->f_mode & FMODE_WRITE) || !(mode & FMODE_WRITE) ||
870 !file->f_op->write)
871 lo_flags |= LO_FLAGS_READ_ONLY;
872
873 lo_blocksize = S_ISBLK(inode->i_mode) ?
874 inode->i_bdev->bd_block_size : PAGE_SIZE;
875
876 error = -EFBIG;
877 size = get_loop_size(lo, file);
878 if ((loff_t)(sector_t)size != size)
879 goto out_putf;
880
881 error = 0;
882
883 set_device_ro(bdev, (lo_flags & LO_FLAGS_READ_ONLY) != 0);
884
885 lo->lo_blocksize = lo_blocksize;
886 lo->lo_device = bdev;
887 lo->lo_flags = lo_flags;
888 lo->lo_backing_file = file;
889 lo->transfer = transfer_none;
890 lo->ioctl = NULL;
891 lo->lo_sizelimit = 0;
892 lo->lo_bio_count = 0;
893 lo->old_gfp_mask = mapping_gfp_mask(mapping);
894 mapping_set_gfp_mask(mapping, lo->old_gfp_mask & ~(__GFP_IO|__GFP_FS));
895
896 bio_list_init(&lo->lo_bio_list);
897
898 if (!(lo_flags & LO_FLAGS_READ_ONLY) && file->f_op->fsync)
899 blk_queue_flush(lo->lo_queue, REQ_FLUSH);
900
901 set_capacity(lo->lo_disk, size);
902 bd_set_size(bdev, size << 9);
903 loop_sysfs_init(lo);
904 /* let user-space know about the new size */
905 kobject_uevent(&disk_to_dev(bdev->bd_disk)->kobj, KOBJ_CHANGE);
906
907 set_blocksize(bdev, lo_blocksize);
908
909 lo->lo_thread = kthread_create(loop_thread, lo, "loop%d",
910 lo->lo_number);
911 if (IS_ERR(lo->lo_thread)) {
912 error = PTR_ERR(lo->lo_thread);
913 goto out_clr;
914 }
915 lo->lo_state = Lo_bound;
916 wake_up_process(lo->lo_thread);
917 if (part_shift)
918 lo->lo_flags |= LO_FLAGS_PARTSCAN;
919 if (lo->lo_flags & LO_FLAGS_PARTSCAN)
920 ioctl_by_bdev(bdev, BLKRRPART, 0);
921
922 /* Grab the block_device to prevent its destruction after we
923 * put /dev/loopXX inode. Later in loop_clr_fd() we bdput(bdev).
924 */
925 bdgrab(bdev);
926 return 0;
927
928out_clr:
929 loop_sysfs_exit(lo);
930 lo->lo_thread = NULL;
931 lo->lo_device = NULL;
932 lo->lo_backing_file = NULL;
933 lo->lo_flags = 0;
934 set_capacity(lo->lo_disk, 0);
935 invalidate_bdev(bdev);
936 bd_set_size(bdev, 0);
937 kobject_uevent(&disk_to_dev(bdev->bd_disk)->kobj, KOBJ_CHANGE);
938 mapping_set_gfp_mask(mapping, lo->old_gfp_mask);
939 lo->lo_state = Lo_unbound;
940 out_putf:
941 fput(file);
942 out:
943 /* This is safe: open() is still holding a reference. */
944 module_put(THIS_MODULE);
945 return error;
946}
947
948static int
949loop_release_xfer(struct loop_device *lo)
950{
951 int err = 0;
952 struct loop_func_table *xfer = lo->lo_encryption;
953
954 if (xfer) {
955 if (xfer->release)
956 err = xfer->release(lo);
957 lo->transfer = NULL;
958 lo->lo_encryption = NULL;
959 module_put(xfer->owner);
960 }
961 return err;
962}
963
964static int
965loop_init_xfer(struct loop_device *lo, struct loop_func_table *xfer,
966 const struct loop_info64 *i)
967{
968 int err = 0;
969
970 if (xfer) {
971 struct module *owner = xfer->owner;
972
973 if (!try_module_get(owner))
974 return -EINVAL;
975 if (xfer->init)
976 err = xfer->init(lo, i);
977 if (err)
978 module_put(owner);
979 else
980 lo->lo_encryption = xfer;
981 }
982 return err;
983}
984
985static int loop_clr_fd(struct loop_device *lo)
986{
987 struct file *filp = lo->lo_backing_file;
988 gfp_t gfp = lo->old_gfp_mask;
989 struct block_device *bdev = lo->lo_device;
990
991 if (lo->lo_state != Lo_bound)
992 return -ENXIO;
993
994 /*
995 * If we've explicitly asked to tear down the loop device,
996 * and it has an elevated reference count, set it for auto-teardown when
997 * the last reference goes away. This stops $!~#$@ udev from
998 * preventing teardown because it decided that it needs to run blkid on
999 * the loopback device whenever they appear. xfstests is notorious for
1000 * failing tests because blkid via udev races with a losetup
1001 * <dev>/do something like mkfs/losetup -d <dev> causing the losetup -d
1002 * command to fail with EBUSY.
1003 */
1004 if (lo->lo_refcnt > 1) {
1005 lo->lo_flags |= LO_FLAGS_AUTOCLEAR;
1006 mutex_unlock(&lo->lo_ctl_mutex);
1007 return 0;
1008 }
1009
1010 if (filp == NULL)
1011 return -EINVAL;
1012
1013 spin_lock_irq(&lo->lo_lock);
1014 lo->lo_state = Lo_rundown;
1015 spin_unlock_irq(&lo->lo_lock);
1016
1017 kthread_stop(lo->lo_thread);
1018
1019 spin_lock_irq(&lo->lo_lock);
1020 lo->lo_backing_file = NULL;
1021 spin_unlock_irq(&lo->lo_lock);
1022
1023 loop_release_xfer(lo);
1024 lo->transfer = NULL;
1025 lo->ioctl = NULL;
1026 lo->lo_device = NULL;
1027 lo->lo_encryption = NULL;
1028 lo->lo_offset = 0;
1029 lo->lo_sizelimit = 0;
1030 lo->lo_encrypt_key_size = 0;
1031 lo->lo_thread = NULL;
1032 memset(lo->lo_encrypt_key, 0, LO_KEY_SIZE);
1033 memset(lo->lo_crypt_name, 0, LO_NAME_SIZE);
1034 memset(lo->lo_file_name, 0, LO_NAME_SIZE);
1035 if (bdev) {
1036 bdput(bdev);
1037 invalidate_bdev(bdev);
1038 }
1039 set_capacity(lo->lo_disk, 0);
1040 loop_sysfs_exit(lo);
1041 if (bdev) {
1042 bd_set_size(bdev, 0);
1043 /* let user-space know about this change */
1044 kobject_uevent(&disk_to_dev(bdev->bd_disk)->kobj, KOBJ_CHANGE);
1045 }
1046 mapping_set_gfp_mask(filp->f_mapping, gfp);
1047 lo->lo_state = Lo_unbound;
1048 /* This is safe: open() is still holding a reference. */
1049 module_put(THIS_MODULE);
1050 if (lo->lo_flags & LO_FLAGS_PARTSCAN && bdev)
1051 ioctl_by_bdev(bdev, BLKRRPART, 0);
1052 lo->lo_flags = 0;
1053 if (!part_shift)
1054 lo->lo_disk->flags |= GENHD_FL_NO_PART_SCAN;
1055 mutex_unlock(&lo->lo_ctl_mutex);
1056 /*
1057 * Need not hold lo_ctl_mutex to fput backing file.
1058 * Calling fput holding lo_ctl_mutex triggers a circular
1059 * lock dependency possibility warning as fput can take
1060 * bd_mutex which is usually taken before lo_ctl_mutex.
1061 */
1062 fput(filp);
1063 return 0;
1064}
1065
1066static int
1067loop_set_status(struct loop_device *lo, const struct loop_info64 *info)
1068{
1069 int err;
1070 struct loop_func_table *xfer;
1071 kuid_t uid = current_uid();
1072
1073 if (lo->lo_encrypt_key_size &&
1074 !uid_eq(lo->lo_key_owner, uid) &&
1075 !capable(CAP_SYS_ADMIN))
1076 return -EPERM;
1077 if (lo->lo_state != Lo_bound)
1078 return -ENXIO;
1079 if ((unsigned int) info->lo_encrypt_key_size > LO_KEY_SIZE)
1080 return -EINVAL;
1081
1082 err = loop_release_xfer(lo);
1083 if (err)
1084 return err;
1085
1086 if (info->lo_encrypt_type) {
1087 unsigned int type = info->lo_encrypt_type;
1088
1089 if (type >= MAX_LO_CRYPT)
1090 return -EINVAL;
1091 xfer = xfer_funcs[type];
1092 if (xfer == NULL)
1093 return -EINVAL;
1094 } else
1095 xfer = NULL;
1096
1097 err = loop_init_xfer(lo, xfer, info);
1098 if (err)
1099 return err;
1100
1101 if (lo->lo_offset != info->lo_offset ||
1102 lo->lo_sizelimit != info->lo_sizelimit)
1103 if (figure_loop_size(lo, info->lo_offset, info->lo_sizelimit))
1104 return -EFBIG;
1105
1106 loop_config_discard(lo);
1107
1108 memcpy(lo->lo_file_name, info->lo_file_name, LO_NAME_SIZE);
1109 memcpy(lo->lo_crypt_name, info->lo_crypt_name, LO_NAME_SIZE);
1110 lo->lo_file_name[LO_NAME_SIZE-1] = 0;
1111 lo->lo_crypt_name[LO_NAME_SIZE-1] = 0;
1112
1113 if (!xfer)
1114 xfer = &none_funcs;
1115 lo->transfer = xfer->transfer;
1116 lo->ioctl = xfer->ioctl;
1117
1118 if ((lo->lo_flags & LO_FLAGS_AUTOCLEAR) !=
1119 (info->lo_flags & LO_FLAGS_AUTOCLEAR))
1120 lo->lo_flags ^= LO_FLAGS_AUTOCLEAR;
1121
1122 if ((info->lo_flags & LO_FLAGS_PARTSCAN) &&
1123 !(lo->lo_flags & LO_FLAGS_PARTSCAN)) {
1124 lo->lo_flags |= LO_FLAGS_PARTSCAN;
1125 lo->lo_disk->flags &= ~GENHD_FL_NO_PART_SCAN;
1126 ioctl_by_bdev(lo->lo_device, BLKRRPART, 0);
1127 }
1128
1129 lo->lo_encrypt_key_size = info->lo_encrypt_key_size;
1130 lo->lo_init[0] = info->lo_init[0];
1131 lo->lo_init[1] = info->lo_init[1];
1132 if (info->lo_encrypt_key_size) {
1133 memcpy(lo->lo_encrypt_key, info->lo_encrypt_key,
1134 info->lo_encrypt_key_size);
1135 lo->lo_key_owner = uid;
1136 }
1137
1138 return 0;
1139}
1140
1141static int
1142loop_get_status(struct loop_device *lo, struct loop_info64 *info)
1143{
1144 struct file *file = lo->lo_backing_file;
1145 struct kstat stat;
1146 int error;
1147
1148 if (lo->lo_state != Lo_bound)
1149 return -ENXIO;
1150 error = vfs_getattr(&file->f_path, &stat);
1151 if (error)
1152 return error;
1153 memset(info, 0, sizeof(*info));
1154 info->lo_number = lo->lo_number;
1155 info->lo_device = huge_encode_dev(stat.dev);
1156 info->lo_inode = stat.ino;
1157 info->lo_rdevice = huge_encode_dev(lo->lo_device ? stat.rdev : stat.dev);
1158 info->lo_offset = lo->lo_offset;
1159 info->lo_sizelimit = lo->lo_sizelimit;
1160 info->lo_flags = lo->lo_flags;
1161 memcpy(info->lo_file_name, lo->lo_file_name, LO_NAME_SIZE);
1162 memcpy(info->lo_crypt_name, lo->lo_crypt_name, LO_NAME_SIZE);
1163 info->lo_encrypt_type =
1164 lo->lo_encryption ? lo->lo_encryption->number : 0;
1165 if (lo->lo_encrypt_key_size && capable(CAP_SYS_ADMIN)) {
1166 info->lo_encrypt_key_size = lo->lo_encrypt_key_size;
1167 memcpy(info->lo_encrypt_key, lo->lo_encrypt_key,
1168 lo->lo_encrypt_key_size);
1169 }
1170 return 0;
1171}
1172
1173static void
1174loop_info64_from_old(const struct loop_info *info, struct loop_info64 *info64)
1175{
1176 memset(info64, 0, sizeof(*info64));
1177 info64->lo_number = info->lo_number;
1178 info64->lo_device = info->lo_device;
1179 info64->lo_inode = info->lo_inode;
1180 info64->lo_rdevice = info->lo_rdevice;
1181 info64->lo_offset = info->lo_offset;
1182 info64->lo_sizelimit = 0;
1183 info64->lo_encrypt_type = info->lo_encrypt_type;
1184 info64->lo_encrypt_key_size = info->lo_encrypt_key_size;
1185 info64->lo_flags = info->lo_flags;
1186 info64->lo_init[0] = info->lo_init[0];
1187 info64->lo_init[1] = info->lo_init[1];
1188 if (info->lo_encrypt_type == LO_CRYPT_CRYPTOAPI)
1189 memcpy(info64->lo_crypt_name, info->lo_name, LO_NAME_SIZE);
1190 else
1191 memcpy(info64->lo_file_name, info->lo_name, LO_NAME_SIZE);
1192 memcpy(info64->lo_encrypt_key, info->lo_encrypt_key, LO_KEY_SIZE);
1193}
1194
1195static int
1196loop_info64_to_old(const struct loop_info64 *info64, struct loop_info *info)
1197{
1198 memset(info, 0, sizeof(*info));
1199 info->lo_number = info64->lo_number;
1200 info->lo_device = info64->lo_device;
1201 info->lo_inode = info64->lo_inode;
1202 info->lo_rdevice = info64->lo_rdevice;
1203 info->lo_offset = info64->lo_offset;
1204 info->lo_encrypt_type = info64->lo_encrypt_type;
1205 info->lo_encrypt_key_size = info64->lo_encrypt_key_size;
1206 info->lo_flags = info64->lo_flags;
1207 info->lo_init[0] = info64->lo_init[0];
1208 info->lo_init[1] = info64->lo_init[1];
1209 if (info->lo_encrypt_type == LO_CRYPT_CRYPTOAPI)
1210 memcpy(info->lo_name, info64->lo_crypt_name, LO_NAME_SIZE);
1211 else
1212 memcpy(info->lo_name, info64->lo_file_name, LO_NAME_SIZE);
1213 memcpy(info->lo_encrypt_key, info64->lo_encrypt_key, LO_KEY_SIZE);
1214
1215 /* error in case values were truncated */
1216 if (info->lo_device != info64->lo_device ||
1217 info->lo_rdevice != info64->lo_rdevice ||
1218 info->lo_inode != info64->lo_inode ||
1219 info->lo_offset != info64->lo_offset)
1220 return -EOVERFLOW;
1221
1222 return 0;
1223}
1224
1225static int
1226loop_set_status_old(struct loop_device *lo, const struct loop_info __user *arg)
1227{
1228 struct loop_info info;
1229 struct loop_info64 info64;
1230
1231 if (copy_from_user(&info, arg, sizeof (struct loop_info)))
1232 return -EFAULT;
1233 loop_info64_from_old(&info, &info64);
1234 return loop_set_status(lo, &info64);
1235}
1236
1237static int
1238loop_set_status64(struct loop_device *lo, const struct loop_info64 __user *arg)
1239{
1240 struct loop_info64 info64;
1241
1242 if (copy_from_user(&info64, arg, sizeof (struct loop_info64)))
1243 return -EFAULT;
1244 return loop_set_status(lo, &info64);
1245}
1246
1247static int
1248loop_get_status_old(struct loop_device *lo, struct loop_info __user *arg) {
1249 struct loop_info info;
1250 struct loop_info64 info64;
1251 int err = 0;
1252
1253 if (!arg)
1254 err = -EINVAL;
1255 if (!err)
1256 err = loop_get_status(lo, &info64);
1257 if (!err)
1258 err = loop_info64_to_old(&info64, &info);
1259 if (!err && copy_to_user(arg, &info, sizeof(info)))
1260 err = -EFAULT;
1261
1262 return err;
1263}
1264
1265static int
1266loop_get_status64(struct loop_device *lo, struct loop_info64 __user *arg) {
1267 struct loop_info64 info64;
1268 int err = 0;
1269
1270 if (!arg)
1271 err = -EINVAL;
1272 if (!err)
1273 err = loop_get_status(lo, &info64);
1274 if (!err && copy_to_user(arg, &info64, sizeof(info64)))
1275 err = -EFAULT;
1276
1277 return err;
1278}
1279
1280static int loop_set_capacity(struct loop_device *lo, struct block_device *bdev)
1281{
1282 if (unlikely(lo->lo_state != Lo_bound))
1283 return -ENXIO;
1284
1285 return figure_loop_size(lo, lo->lo_offset, lo->lo_sizelimit);
1286}
1287
1288static int lo_ioctl(struct block_device *bdev, fmode_t mode,
1289 unsigned int cmd, unsigned long arg)
1290{
1291 struct loop_device *lo = bdev->bd_disk->private_data;
1292 int err;
1293
1294 mutex_lock_nested(&lo->lo_ctl_mutex, 1);
1295 switch (cmd) {
1296 case LOOP_SET_FD:
1297 err = loop_set_fd(lo, mode, bdev, arg);
1298 break;
1299 case LOOP_CHANGE_FD:
1300 err = loop_change_fd(lo, bdev, arg);
1301 break;
1302 case LOOP_CLR_FD:
1303 /* loop_clr_fd would have unlocked lo_ctl_mutex on success */
1304 err = loop_clr_fd(lo);
1305 if (!err)
1306 goto out_unlocked;
1307 break;
1308 case LOOP_SET_STATUS:
1309 err = -EPERM;
1310 if ((mode & FMODE_WRITE) || capable(CAP_SYS_ADMIN))
1311 err = loop_set_status_old(lo,
1312 (struct loop_info __user *)arg);
1313 break;
1314 case LOOP_GET_STATUS:
1315 err = loop_get_status_old(lo, (struct loop_info __user *) arg);
1316 break;
1317 case LOOP_SET_STATUS64:
1318 err = -EPERM;
1319 if ((mode & FMODE_WRITE) || capable(CAP_SYS_ADMIN))
1320 err = loop_set_status64(lo,
1321 (struct loop_info64 __user *) arg);
1322 break;
1323 case LOOP_GET_STATUS64:
1324 err = loop_get_status64(lo, (struct loop_info64 __user *) arg);
1325 break;
1326 case LOOP_SET_CAPACITY:
1327 err = -EPERM;
1328 if ((mode & FMODE_WRITE) || capable(CAP_SYS_ADMIN))
1329 err = loop_set_capacity(lo, bdev);
1330 break;
1331 default:
1332 err = lo->ioctl ? lo->ioctl(lo, cmd, arg) : -EINVAL;
1333 }
1334 mutex_unlock(&lo->lo_ctl_mutex);
1335
1336out_unlocked:
1337 return err;
1338}
1339
1340#ifdef CONFIG_COMPAT
1341struct compat_loop_info {
1342 compat_int_t lo_number; /* ioctl r/o */
1343 compat_dev_t lo_device; /* ioctl r/o */
1344 compat_ulong_t lo_inode; /* ioctl r/o */
1345 compat_dev_t lo_rdevice; /* ioctl r/o */
1346 compat_int_t lo_offset;
1347 compat_int_t lo_encrypt_type;
1348 compat_int_t lo_encrypt_key_size; /* ioctl w/o */
1349 compat_int_t lo_flags; /* ioctl r/o */
1350 char lo_name[LO_NAME_SIZE];
1351 unsigned char lo_encrypt_key[LO_KEY_SIZE]; /* ioctl w/o */
1352 compat_ulong_t lo_init[2];
1353 char reserved[4];
1354};
1355
1356/*
1357 * Transfer 32-bit compatibility structure in userspace to 64-bit loop info
1358 * - noinlined to reduce stack space usage in main part of driver
1359 */
1360static noinline int
1361loop_info64_from_compat(const struct compat_loop_info __user *arg,
1362 struct loop_info64 *info64)
1363{
1364 struct compat_loop_info info;
1365
1366 if (copy_from_user(&info, arg, sizeof(info)))
1367 return -EFAULT;
1368
1369 memset(info64, 0, sizeof(*info64));
1370 info64->lo_number = info.lo_number;
1371 info64->lo_device = info.lo_device;
1372 info64->lo_inode = info.lo_inode;
1373 info64->lo_rdevice = info.lo_rdevice;
1374 info64->lo_offset = info.lo_offset;
1375 info64->lo_sizelimit = 0;
1376 info64->lo_encrypt_type = info.lo_encrypt_type;
1377 info64->lo_encrypt_key_size = info.lo_encrypt_key_size;
1378 info64->lo_flags = info.lo_flags;
1379 info64->lo_init[0] = info.lo_init[0];
1380 info64->lo_init[1] = info.lo_init[1];
1381 if (info.lo_encrypt_type == LO_CRYPT_CRYPTOAPI)
1382 memcpy(info64->lo_crypt_name, info.lo_name, LO_NAME_SIZE);
1383 else
1384 memcpy(info64->lo_file_name, info.lo_name, LO_NAME_SIZE);
1385 memcpy(info64->lo_encrypt_key, info.lo_encrypt_key, LO_KEY_SIZE);
1386 return 0;
1387}
1388
1389/*
1390 * Transfer 64-bit loop info to 32-bit compatibility structure in userspace
1391 * - noinlined to reduce stack space usage in main part of driver
1392 */
1393static noinline int
1394loop_info64_to_compat(const struct loop_info64 *info64,
1395 struct compat_loop_info __user *arg)
1396{
1397 struct compat_loop_info info;
1398
1399 memset(&info, 0, sizeof(info));
1400 info.lo_number = info64->lo_number;
1401 info.lo_device = info64->lo_device;
1402 info.lo_inode = info64->lo_inode;
1403 info.lo_rdevice = info64->lo_rdevice;
1404 info.lo_offset = info64->lo_offset;
1405 info.lo_encrypt_type = info64->lo_encrypt_type;
1406 info.lo_encrypt_key_size = info64->lo_encrypt_key_size;
1407 info.lo_flags = info64->lo_flags;
1408 info.lo_init[0] = info64->lo_init[0];
1409 info.lo_init[1] = info64->lo_init[1];
1410 if (info.lo_encrypt_type == LO_CRYPT_CRYPTOAPI)
1411 memcpy(info.lo_name, info64->lo_crypt_name, LO_NAME_SIZE);
1412 else
1413 memcpy(info.lo_name, info64->lo_file_name, LO_NAME_SIZE);
1414 memcpy(info.lo_encrypt_key, info64->lo_encrypt_key, LO_KEY_SIZE);
1415
1416 /* error in case values were truncated */
1417 if (info.lo_device != info64->lo_device ||
1418 info.lo_rdevice != info64->lo_rdevice ||
1419 info.lo_inode != info64->lo_inode ||
1420 info.lo_offset != info64->lo_offset ||
1421 info.lo_init[0] != info64->lo_init[0] ||
1422 info.lo_init[1] != info64->lo_init[1])
1423 return -EOVERFLOW;
1424
1425 if (copy_to_user(arg, &info, sizeof(info)))
1426 return -EFAULT;
1427 return 0;
1428}
1429
1430static int
1431loop_set_status_compat(struct loop_device *lo,
1432 const struct compat_loop_info __user *arg)
1433{
1434 struct loop_info64 info64;
1435 int ret;
1436
1437 ret = loop_info64_from_compat(arg, &info64);
1438 if (ret < 0)
1439 return ret;
1440 return loop_set_status(lo, &info64);
1441}
1442
1443static int
1444loop_get_status_compat(struct loop_device *lo,
1445 struct compat_loop_info __user *arg)
1446{
1447 struct loop_info64 info64;
1448 int err = 0;
1449
1450 if (!arg)
1451 err = -EINVAL;
1452 if (!err)
1453 err = loop_get_status(lo, &info64);
1454 if (!err)
1455 err = loop_info64_to_compat(&info64, arg);
1456 return err;
1457}
1458
1459static int lo_compat_ioctl(struct block_device *bdev, fmode_t mode,
1460 unsigned int cmd, unsigned long arg)
1461{
1462 struct loop_device *lo = bdev->bd_disk->private_data;
1463 int err;
1464
1465 switch(cmd) {
1466 case LOOP_SET_STATUS:
1467 mutex_lock(&lo->lo_ctl_mutex);
1468 err = loop_set_status_compat(
1469 lo, (const struct compat_loop_info __user *) arg);
1470 mutex_unlock(&lo->lo_ctl_mutex);
1471 break;
1472 case LOOP_GET_STATUS:
1473 mutex_lock(&lo->lo_ctl_mutex);
1474 err = loop_get_status_compat(
1475 lo, (struct compat_loop_info __user *) arg);
1476 mutex_unlock(&lo->lo_ctl_mutex);
1477 break;
1478 case LOOP_SET_CAPACITY:
1479 case LOOP_CLR_FD:
1480 case LOOP_GET_STATUS64:
1481 case LOOP_SET_STATUS64:
1482 arg = (unsigned long) compat_ptr(arg);
1483 case LOOP_SET_FD:
1484 case LOOP_CHANGE_FD:
1485 err = lo_ioctl(bdev, mode, cmd, arg);
1486 break;
1487 default:
1488 err = -ENOIOCTLCMD;
1489 break;
1490 }
1491 return err;
1492}
1493#endif
1494
1495static int lo_open(struct block_device *bdev, fmode_t mode)
1496{
1497 struct loop_device *lo;
1498 int err = 0;
1499
1500 mutex_lock(&loop_index_mutex);
1501 lo = bdev->bd_disk->private_data;
1502 if (!lo) {
1503 err = -ENXIO;
1504 goto out;
1505 }
1506
1507 mutex_lock(&lo->lo_ctl_mutex);
1508 lo->lo_refcnt++;
1509 mutex_unlock(&lo->lo_ctl_mutex);
1510out:
1511 mutex_unlock(&loop_index_mutex);
1512 return err;
1513}
1514
1515static void lo_release(struct gendisk *disk, fmode_t mode)
1516{
1517 struct loop_device *lo = disk->private_data;
1518 int err;
1519
1520 mutex_lock(&lo->lo_ctl_mutex);
1521
1522 if (--lo->lo_refcnt)
1523 goto out;
1524
1525 if (lo->lo_flags & LO_FLAGS_AUTOCLEAR) {
1526 /*
1527 * In autoclear mode, stop the loop thread
1528 * and remove configuration after last close.
1529 */
1530 err = loop_clr_fd(lo);
1531 if (!err)
1532 return;
1533 } else {
1534 /*
1535 * Otherwise keep thread (if running) and config,
1536 * but flush possible ongoing bios in thread.
1537 */
1538 loop_flush(lo);
1539 }
1540
1541out:
1542 mutex_unlock(&lo->lo_ctl_mutex);
1543}
1544
1545static const struct block_device_operations lo_fops = {
1546 .owner = THIS_MODULE,
1547 .open = lo_open,
1548 .release = lo_release,
1549 .ioctl = lo_ioctl,
1550#ifdef CONFIG_COMPAT
1551 .compat_ioctl = lo_compat_ioctl,
1552#endif
1553};
1554
1555/*
1556 * And now the modules code and kernel interface.
1557 */
1558static int max_loop;
1559module_param(max_loop, int, S_IRUGO);
1560MODULE_PARM_DESC(max_loop, "Maximum number of loop devices");
1561module_param(max_part, int, S_IRUGO);
1562MODULE_PARM_DESC(max_part, "Maximum number of partitions per loop device");
1563MODULE_LICENSE("GPL");
1564MODULE_ALIAS_BLOCKDEV_MAJOR(LOOP_MAJOR);
1565
1566int loop_register_transfer(struct loop_func_table *funcs)
1567{
1568 unsigned int n = funcs->number;
1569
1570 if (n >= MAX_LO_CRYPT || xfer_funcs[n])
1571 return -EINVAL;
1572 xfer_funcs[n] = funcs;
1573 return 0;
1574}
1575
1576static int unregister_transfer_cb(int id, void *ptr, void *data)
1577{
1578 struct loop_device *lo = ptr;
1579 struct loop_func_table *xfer = data;
1580
1581 mutex_lock(&lo->lo_ctl_mutex);
1582 if (lo->lo_encryption == xfer)
1583 loop_release_xfer(lo);
1584 mutex_unlock(&lo->lo_ctl_mutex);
1585 return 0;
1586}
1587
1588int loop_unregister_transfer(int number)
1589{
1590 unsigned int n = number;
1591 struct loop_func_table *xfer;
1592
1593 if (n == 0 || n >= MAX_LO_CRYPT || (xfer = xfer_funcs[n]) == NULL)
1594 return -EINVAL;
1595
1596 xfer_funcs[n] = NULL;
1597 idr_for_each(&loop_index_idr, &unregister_transfer_cb, xfer);
1598 return 0;
1599}
1600
1601EXPORT_SYMBOL(loop_register_transfer);
1602EXPORT_SYMBOL(loop_unregister_transfer);
1603
1604static int loop_add(struct loop_device **l, int i)
1605{
1606 struct loop_device *lo;
1607 struct gendisk *disk;
1608 int err;
1609
1610 err = -ENOMEM;
1611 lo = kzalloc(sizeof(*lo), GFP_KERNEL);
1612 if (!lo)
1613 goto out;
1614
1615 lo->lo_state = Lo_unbound;
1616
1617 /* allocate id, if @id >= 0, we're requesting that specific id */
1618 if (i >= 0) {
1619 err = idr_alloc(&loop_index_idr, lo, i, i + 1, GFP_KERNEL);
1620 if (err == -ENOSPC)
1621 err = -EEXIST;
1622 } else {
1623 err = idr_alloc(&loop_index_idr, lo, 0, 0, GFP_KERNEL);
1624 }
1625 if (err < 0)
1626 goto out_free_dev;
1627 i = err;
1628
1629 err = -ENOMEM;
1630 lo->lo_queue = blk_alloc_queue(GFP_KERNEL);
1631 if (!lo->lo_queue)
1632 goto out_free_idr;
1633
1634 /*
1635 * set queue make_request_fn
1636 */
1637 blk_queue_make_request(lo->lo_queue, loop_make_request);
1638 lo->lo_queue->queuedata = lo;
1639
1640 disk = lo->lo_disk = alloc_disk(1 << part_shift);
1641 if (!disk)
1642 goto out_free_queue;
1643
1644 /*
1645 * Disable partition scanning by default. The in-kernel partition
1646 * scanning can be requested individually per-device during its
1647 * setup. Userspace can always add and remove partitions from all
1648 * devices. The needed partition minors are allocated from the
1649 * extended minor space, the main loop device numbers will continue
1650 * to match the loop minors, regardless of the number of partitions
1651 * used.
1652 *
1653 * If max_part is given, partition scanning is globally enabled for
1654 * all loop devices. The minors for the main loop devices will be
1655 * multiples of max_part.
1656 *
1657 * Note: Global-for-all-devices, set-only-at-init, read-only module
1658 * parameteters like 'max_loop' and 'max_part' make things needlessly
1659 * complicated, are too static, inflexible and may surprise
1660 * userspace tools. Parameters like this in general should be avoided.
1661 */
1662 if (!part_shift)
1663 disk->flags |= GENHD_FL_NO_PART_SCAN;
1664 disk->flags |= GENHD_FL_EXT_DEVT;
1665 mutex_init(&lo->lo_ctl_mutex);
1666 lo->lo_number = i;
1667 lo->lo_thread = NULL;
1668 init_waitqueue_head(&lo->lo_event);
1669 init_waitqueue_head(&lo->lo_req_wait);
1670 spin_lock_init(&lo->lo_lock);
1671 disk->major = LOOP_MAJOR;
1672 disk->first_minor = i << part_shift;
1673 disk->fops = &lo_fops;
1674 disk->private_data = lo;
1675 disk->queue = lo->lo_queue;
1676 sprintf(disk->disk_name, "loop%d", i);
1677 add_disk(disk);
1678 *l = lo;
1679 return lo->lo_number;
1680
1681out_free_queue:
1682 blk_cleanup_queue(lo->lo_queue);
1683out_free_idr:
1684 idr_remove(&loop_index_idr, i);
1685out_free_dev:
1686 kfree(lo);
1687out:
1688 return err;
1689}
1690
1691static void loop_remove(struct loop_device *lo)
1692{
1693 del_gendisk(lo->lo_disk);
1694 blk_cleanup_queue(lo->lo_queue);
1695 put_disk(lo->lo_disk);
1696 kfree(lo);
1697}
1698
1699static int find_free_cb(int id, void *ptr, void *data)
1700{
1701 struct loop_device *lo = ptr;
1702 struct loop_device **l = data;
1703
1704 if (lo->lo_state == Lo_unbound) {
1705 *l = lo;
1706 return 1;
1707 }
1708 return 0;
1709}
1710
1711static int loop_lookup(struct loop_device **l, int i)
1712{
1713 struct loop_device *lo;
1714 int ret = -ENODEV;
1715
1716 if (i < 0) {
1717 int err;
1718
1719 err = idr_for_each(&loop_index_idr, &find_free_cb, &lo);
1720 if (err == 1) {
1721 *l = lo;
1722 ret = lo->lo_number;
1723 }
1724 goto out;
1725 }
1726
1727 /* lookup and return a specific i */
1728 lo = idr_find(&loop_index_idr, i);
1729 if (lo) {
1730 *l = lo;
1731 ret = lo->lo_number;
1732 }
1733out:
1734 return ret;
1735}
1736
1737static struct kobject *loop_probe(dev_t dev, int *part, void *data)
1738{
1739 struct loop_device *lo;
1740 struct kobject *kobj;
1741 int err;
1742
1743 mutex_lock(&loop_index_mutex);
1744 err = loop_lookup(&lo, MINOR(dev) >> part_shift);
1745 if (err < 0)
1746 err = loop_add(&lo, MINOR(dev) >> part_shift);
1747 if (err < 0)
1748 kobj = NULL;
1749 else
1750 kobj = get_disk(lo->lo_disk);
1751 mutex_unlock(&loop_index_mutex);
1752
1753 *part = 0;
1754 return kobj;
1755}
1756
1757static long loop_control_ioctl(struct file *file, unsigned int cmd,
1758 unsigned long parm)
1759{
1760 struct loop_device *lo;
1761 int ret = -ENOSYS;
1762
1763 mutex_lock(&loop_index_mutex);
1764 switch (cmd) {
1765 case LOOP_CTL_ADD:
1766 ret = loop_lookup(&lo, parm);
1767 if (ret >= 0) {
1768 ret = -EEXIST;
1769 break;
1770 }
1771 ret = loop_add(&lo, parm);
1772 break;
1773 case LOOP_CTL_REMOVE:
1774 ret = loop_lookup(&lo, parm);
1775 if (ret < 0)
1776 break;
1777 mutex_lock(&lo->lo_ctl_mutex);
1778 if (lo->lo_state != Lo_unbound) {
1779 ret = -EBUSY;
1780 mutex_unlock(&lo->lo_ctl_mutex);
1781 break;
1782 }
1783 if (lo->lo_refcnt > 0) {
1784 ret = -EBUSY;
1785 mutex_unlock(&lo->lo_ctl_mutex);
1786 break;
1787 }
1788 lo->lo_disk->private_data = NULL;
1789 mutex_unlock(&lo->lo_ctl_mutex);
1790 idr_remove(&loop_index_idr, lo->lo_number);
1791 loop_remove(lo);
1792 break;
1793 case LOOP_CTL_GET_FREE:
1794 ret = loop_lookup(&lo, -1);
1795 if (ret >= 0)
1796 break;
1797 ret = loop_add(&lo, -1);
1798 }
1799 mutex_unlock(&loop_index_mutex);
1800
1801 return ret;
1802}
1803
1804static const struct file_operations loop_ctl_fops = {
1805 .open = nonseekable_open,
1806 .unlocked_ioctl = loop_control_ioctl,
1807 .compat_ioctl = loop_control_ioctl,
1808 .owner = THIS_MODULE,
1809 .llseek = noop_llseek,
1810};
1811
1812static struct miscdevice loop_misc = {
1813 .minor = LOOP_CTRL_MINOR,
1814 .name = "loop-control",
1815 .fops = &loop_ctl_fops,
1816};
1817
1818MODULE_ALIAS_MISCDEV(LOOP_CTRL_MINOR);
1819MODULE_ALIAS("devname:loop-control");
1820
1821static int __init loop_init(void)
1822{
1823 int i, nr;
1824 unsigned long range;
1825 struct loop_device *lo;
1826 int err;
1827
1828 err = misc_register(&loop_misc);
1829 if (err < 0)
1830 return err;
1831
1832 part_shift = 0;
1833 if (max_part > 0) {
1834 part_shift = fls(max_part);
1835
1836 /*
1837 * Adjust max_part according to part_shift as it is exported
1838 * to user space so that user can decide correct minor number
1839 * if [s]he want to create more devices.
1840 *
1841 * Note that -1 is required because partition 0 is reserved
1842 * for the whole disk.
1843 */
1844 max_part = (1UL << part_shift) - 1;
1845 }
1846
1847 if ((1UL << part_shift) > DISK_MAX_PARTS) {
1848 err = -EINVAL;
1849 goto misc_out;
1850 }
1851
1852 if (max_loop > 1UL << (MINORBITS - part_shift)) {
1853 err = -EINVAL;
1854 goto misc_out;
1855 }
1856
1857 /*
1858 * If max_loop is specified, create that many devices upfront.
1859 * This also becomes a hard limit. If max_loop is not specified,
1860 * create CONFIG_BLK_DEV_LOOP_MIN_COUNT loop devices at module
1861 * init time. Loop devices can be requested on-demand with the
1862 * /dev/loop-control interface, or be instantiated by accessing
1863 * a 'dead' device node.
1864 */
1865 if (max_loop) {
1866 nr = max_loop;
1867 range = max_loop << part_shift;
1868 } else {
1869 nr = CONFIG_BLK_DEV_LOOP_MIN_COUNT;
1870 range = 1UL << MINORBITS;
1871 }
1872
1873 if (register_blkdev(LOOP_MAJOR, "loop")) {
1874 err = -EIO;
1875 goto misc_out;
1876 }
1877
1878 blk_register_region(MKDEV(LOOP_MAJOR, 0), range,
1879 THIS_MODULE, loop_probe, NULL, NULL);
1880
1881 /* pre-create number of devices given by config or max_loop */
1882 mutex_lock(&loop_index_mutex);
1883 for (i = 0; i < nr; i++)
1884 loop_add(&lo, i);
1885 mutex_unlock(&loop_index_mutex);
1886
1887 printk(KERN_INFO "loop: module loaded\n");
1888 return 0;
1889
1890misc_out:
1891 misc_deregister(&loop_misc);
1892 return err;
1893}
1894
1895static int loop_exit_cb(int id, void *ptr, void *data)
1896{
1897 struct loop_device *lo = ptr;
1898
1899 loop_remove(lo);
1900 return 0;
1901}
1902
1903static void __exit loop_exit(void)
1904{
1905 unsigned long range;
1906
1907 range = max_loop ? max_loop << part_shift : 1UL << MINORBITS;
1908
1909 idr_for_each(&loop_index_idr, &loop_exit_cb, NULL);
1910 idr_destroy(&loop_index_idr);
1911
1912 blk_unregister_region(MKDEV(LOOP_MAJOR, 0), range);
1913 unregister_blkdev(LOOP_MAJOR, "loop");
1914
1915 misc_deregister(&loop_misc);
1916}
1917
1918module_init(loop_init);
1919module_exit(loop_exit);
1920
1921#ifndef MODULE
1922static int __init max_loop_setup(char *str)
1923{
1924 max_loop = simple_strtol(str, NULL, 0);
1925 return 1;
1926}
1927
1928__setup("max_loop=", max_loop_setup);
1929#endif