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6#include <linux/cred.h>
7#include <linux/file.h>
8#include <linux/mount.h>
9#include <linux/xattr.h>
10#include <linux/uio.h>
11#include <linux/uaccess.h>
12#include "overlayfs.h"
13
14static char ovl_whatisit(struct inode *inode, struct inode *realinode)
15{
16 if (realinode != ovl_inode_upper(inode))
17 return 'l';
18 if (ovl_has_upperdata(inode))
19 return 'u';
20 else
21 return 'm';
22}
23
24static struct file *ovl_open_realfile(const struct file *file,
25 struct inode *realinode)
26{
27 struct inode *inode = file_inode(file);
28 struct file *realfile;
29 const struct cred *old_cred;
30 int flags = file->f_flags | O_NOATIME | FMODE_NONOTIFY;
31
32 old_cred = ovl_override_creds(inode->i_sb);
33 realfile = open_with_fake_path(&file->f_path, flags, realinode,
34 current_cred());
35 revert_creds(old_cred);
36
37 pr_debug("open(%p[%pD2/%c], 0%o) -> (%p, 0%o)\n",
38 file, file, ovl_whatisit(inode, realinode), file->f_flags,
39 realfile, IS_ERR(realfile) ? 0 : realfile->f_flags);
40
41 return realfile;
42}
43
44#define OVL_SETFL_MASK (O_APPEND | O_NONBLOCK | O_NDELAY | O_DIRECT)
45
46static int ovl_change_flags(struct file *file, unsigned int flags)
47{
48 struct inode *inode = file_inode(file);
49 int err;
50
51
52 flags |= O_NOATIME | FMODE_NONOTIFY;
53
54
55 if (WARN_ON((file->f_flags ^ flags) & ~OVL_SETFL_MASK))
56 return -EIO;
57
58 flags &= OVL_SETFL_MASK;
59
60 if (((flags ^ file->f_flags) & O_APPEND) && IS_APPEND(inode))
61 return -EPERM;
62
63 if (flags & O_DIRECT) {
64 if (!file->f_mapping->a_ops ||
65 !file->f_mapping->a_ops->direct_IO)
66 return -EINVAL;
67 }
68
69 if (file->f_op->check_flags) {
70 err = file->f_op->check_flags(flags);
71 if (err)
72 return err;
73 }
74
75 spin_lock(&file->f_lock);
76 file->f_flags = (file->f_flags & ~OVL_SETFL_MASK) | flags;
77 spin_unlock(&file->f_lock);
78
79 return 0;
80}
81
82static int ovl_real_fdget_meta(const struct file *file, struct fd *real,
83 bool allow_meta)
84{
85 struct inode *inode = file_inode(file);
86 struct inode *realinode;
87
88 real->flags = 0;
89 real->file = file->private_data;
90
91 if (allow_meta)
92 realinode = ovl_inode_real(inode);
93 else
94 realinode = ovl_inode_realdata(inode);
95
96
97 if (unlikely(file_inode(real->file) != realinode)) {
98 real->flags = FDPUT_FPUT;
99 real->file = ovl_open_realfile(file, realinode);
100
101 return PTR_ERR_OR_ZERO(real->file);
102 }
103
104
105 if (unlikely((file->f_flags ^ real->file->f_flags) & ~O_NOATIME))
106 return ovl_change_flags(real->file, file->f_flags);
107
108 return 0;
109}
110
111static int ovl_real_fdget(const struct file *file, struct fd *real)
112{
113 return ovl_real_fdget_meta(file, real, false);
114}
115
116static int ovl_open(struct inode *inode, struct file *file)
117{
118 struct file *realfile;
119 int err;
120
121 err = ovl_maybe_copy_up(file_dentry(file), file->f_flags);
122 if (err)
123 return err;
124
125
126 file->f_flags &= ~(O_CREAT | O_EXCL | O_NOCTTY | O_TRUNC);
127
128 realfile = ovl_open_realfile(file, ovl_inode_realdata(inode));
129 if (IS_ERR(realfile))
130 return PTR_ERR(realfile);
131
132 file->private_data = realfile;
133
134 return 0;
135}
136
137static int ovl_release(struct inode *inode, struct file *file)
138{
139 fput(file->private_data);
140
141 return 0;
142}
143
144static loff_t ovl_llseek(struct file *file, loff_t offset, int whence)
145{
146 struct inode *inode = file_inode(file);
147 struct fd real;
148 const struct cred *old_cred;
149 ssize_t ret;
150
151
152
153
154
155 if (offset == 0) {
156 if (whence == SEEK_CUR)
157 return file->f_pos;
158
159 if (whence == SEEK_SET)
160 return vfs_setpos(file, 0, 0);
161 }
162
163 ret = ovl_real_fdget(file, &real);
164 if (ret)
165 return ret;
166
167
168
169
170
171
172
173
174 inode_lock(inode);
175 real.file->f_pos = file->f_pos;
176
177 old_cred = ovl_override_creds(inode->i_sb);
178 ret = vfs_llseek(real.file, offset, whence);
179 revert_creds(old_cred);
180
181 file->f_pos = real.file->f_pos;
182 inode_unlock(inode);
183
184 fdput(real);
185
186 return ret;
187}
188
189static void ovl_file_accessed(struct file *file)
190{
191 struct inode *inode, *upperinode;
192
193 if (file->f_flags & O_NOATIME)
194 return;
195
196 inode = file_inode(file);
197 upperinode = ovl_inode_upper(inode);
198
199 if (!upperinode)
200 return;
201
202 if ((!timespec64_equal(&inode->i_mtime, &upperinode->i_mtime) ||
203 !timespec64_equal(&inode->i_ctime, &upperinode->i_ctime))) {
204 inode->i_mtime = upperinode->i_mtime;
205 inode->i_ctime = upperinode->i_ctime;
206 }
207
208 touch_atime(&file->f_path);
209}
210
211static rwf_t ovl_iocb_to_rwf(struct kiocb *iocb)
212{
213 int ifl = iocb->ki_flags;
214 rwf_t flags = 0;
215
216 if (ifl & IOCB_NOWAIT)
217 flags |= RWF_NOWAIT;
218 if (ifl & IOCB_HIPRI)
219 flags |= RWF_HIPRI;
220 if (ifl & IOCB_DSYNC)
221 flags |= RWF_DSYNC;
222 if (ifl & IOCB_SYNC)
223 flags |= RWF_SYNC;
224
225 return flags;
226}
227
228static ssize_t ovl_read_iter(struct kiocb *iocb, struct iov_iter *iter)
229{
230 struct file *file = iocb->ki_filp;
231 struct fd real;
232 const struct cred *old_cred;
233 ssize_t ret;
234
235 if (!iov_iter_count(iter))
236 return 0;
237
238 ret = ovl_real_fdget(file, &real);
239 if (ret)
240 return ret;
241
242 old_cred = ovl_override_creds(file_inode(file)->i_sb);
243 ret = vfs_iter_read(real.file, iter, &iocb->ki_pos,
244 ovl_iocb_to_rwf(iocb));
245 revert_creds(old_cred);
246
247 ovl_file_accessed(file);
248
249 fdput(real);
250
251 return ret;
252}
253
254static ssize_t ovl_write_iter(struct kiocb *iocb, struct iov_iter *iter)
255{
256 struct file *file = iocb->ki_filp;
257 struct inode *inode = file_inode(file);
258 struct fd real;
259 const struct cred *old_cred;
260 ssize_t ret;
261
262 if (!iov_iter_count(iter))
263 return 0;
264
265 inode_lock(inode);
266
267 ovl_copyattr(ovl_inode_real(inode), inode);
268 ret = file_remove_privs(file);
269 if (ret)
270 goto out_unlock;
271
272 ret = ovl_real_fdget(file, &real);
273 if (ret)
274 goto out_unlock;
275
276 old_cred = ovl_override_creds(file_inode(file)->i_sb);
277 file_start_write(real.file);
278 ret = vfs_iter_write(real.file, iter, &iocb->ki_pos,
279 ovl_iocb_to_rwf(iocb));
280 file_end_write(real.file);
281 revert_creds(old_cred);
282
283
284 ovl_copyattr(ovl_inode_real(inode), inode);
285
286 fdput(real);
287
288out_unlock:
289 inode_unlock(inode);
290
291 return ret;
292}
293
294static int ovl_fsync(struct file *file, loff_t start, loff_t end, int datasync)
295{
296 struct fd real;
297 const struct cred *old_cred;
298 int ret;
299
300 ret = ovl_real_fdget_meta(file, &real, !datasync);
301 if (ret)
302 return ret;
303
304
305 if (file_inode(real.file) == ovl_inode_upper(file_inode(file))) {
306 old_cred = ovl_override_creds(file_inode(file)->i_sb);
307 ret = vfs_fsync_range(real.file, start, end, datasync);
308 revert_creds(old_cred);
309 }
310
311 fdput(real);
312
313 return ret;
314}
315
316static int ovl_mmap(struct file *file, struct vm_area_struct *vma)
317{
318 struct file *realfile = file->private_data;
319 const struct cred *old_cred;
320 int ret;
321
322 if (!realfile->f_op->mmap)
323 return -ENODEV;
324
325 if (WARN_ON(file != vma->vm_file))
326 return -EIO;
327
328 vma->vm_file = get_file(realfile);
329
330 old_cred = ovl_override_creds(file_inode(file)->i_sb);
331 ret = call_mmap(vma->vm_file, vma);
332 revert_creds(old_cred);
333
334 if (ret) {
335
336 fput(realfile);
337 } else {
338
339 fput(file);
340 }
341
342 ovl_file_accessed(file);
343
344 return ret;
345}
346
347static long ovl_fallocate(struct file *file, int mode, loff_t offset, loff_t len)
348{
349 struct inode *inode = file_inode(file);
350 struct fd real;
351 const struct cred *old_cred;
352 int ret;
353
354 ret = ovl_real_fdget(file, &real);
355 if (ret)
356 return ret;
357
358 old_cred = ovl_override_creds(file_inode(file)->i_sb);
359 ret = vfs_fallocate(real.file, mode, offset, len);
360 revert_creds(old_cred);
361
362
363 ovl_copyattr(ovl_inode_real(inode), inode);
364
365 fdput(real);
366
367 return ret;
368}
369
370static int ovl_fadvise(struct file *file, loff_t offset, loff_t len, int advice)
371{
372 struct fd real;
373 const struct cred *old_cred;
374 int ret;
375
376 ret = ovl_real_fdget(file, &real);
377 if (ret)
378 return ret;
379
380 old_cred = ovl_override_creds(file_inode(file)->i_sb);
381 ret = vfs_fadvise(real.file, offset, len, advice);
382 revert_creds(old_cred);
383
384 fdput(real);
385
386 return ret;
387}
388
389static long ovl_real_ioctl(struct file *file, unsigned int cmd,
390 unsigned long arg)
391{
392 struct fd real;
393 const struct cred *old_cred;
394 long ret;
395
396 ret = ovl_real_fdget(file, &real);
397 if (ret)
398 return ret;
399
400 old_cred = ovl_override_creds(file_inode(file)->i_sb);
401 ret = vfs_ioctl(real.file, cmd, arg);
402 revert_creds(old_cred);
403
404 fdput(real);
405
406 return ret;
407}
408
409static long ovl_ioctl_set_flags(struct file *file, unsigned int cmd,
410 unsigned long arg, unsigned int iflags)
411{
412 long ret;
413 struct inode *inode = file_inode(file);
414 unsigned int old_iflags;
415
416 if (!inode_owner_or_capable(inode))
417 return -EACCES;
418
419 ret = mnt_want_write_file(file);
420 if (ret)
421 return ret;
422
423 inode_lock(inode);
424
425
426 ret = -EPERM;
427 old_iflags = READ_ONCE(inode->i_flags);
428 if (((iflags ^ old_iflags) & (S_APPEND | S_IMMUTABLE)) &&
429 !capable(CAP_LINUX_IMMUTABLE))
430 goto unlock;
431
432 ret = ovl_maybe_copy_up(file_dentry(file), O_WRONLY);
433 if (ret)
434 goto unlock;
435
436 ret = ovl_real_ioctl(file, cmd, arg);
437
438 ovl_copyflags(ovl_inode_real(inode), inode);
439unlock:
440 inode_unlock(inode);
441
442 mnt_drop_write_file(file);
443
444 return ret;
445
446}
447
448static unsigned int ovl_fsflags_to_iflags(unsigned int flags)
449{
450 unsigned int iflags = 0;
451
452 if (flags & FS_SYNC_FL)
453 iflags |= S_SYNC;
454 if (flags & FS_APPEND_FL)
455 iflags |= S_APPEND;
456 if (flags & FS_IMMUTABLE_FL)
457 iflags |= S_IMMUTABLE;
458 if (flags & FS_NOATIME_FL)
459 iflags |= S_NOATIME;
460
461 return iflags;
462}
463
464static long ovl_ioctl_set_fsflags(struct file *file, unsigned int cmd,
465 unsigned long arg)
466{
467 unsigned int flags;
468
469 if (get_user(flags, (int __user *) arg))
470 return -EFAULT;
471
472 return ovl_ioctl_set_flags(file, cmd, arg,
473 ovl_fsflags_to_iflags(flags));
474}
475
476static unsigned int ovl_fsxflags_to_iflags(unsigned int xflags)
477{
478 unsigned int iflags = 0;
479
480 if (xflags & FS_XFLAG_SYNC)
481 iflags |= S_SYNC;
482 if (xflags & FS_XFLAG_APPEND)
483 iflags |= S_APPEND;
484 if (xflags & FS_XFLAG_IMMUTABLE)
485 iflags |= S_IMMUTABLE;
486 if (xflags & FS_XFLAG_NOATIME)
487 iflags |= S_NOATIME;
488
489 return iflags;
490}
491
492static long ovl_ioctl_set_fsxflags(struct file *file, unsigned int cmd,
493 unsigned long arg)
494{
495 struct fsxattr fa;
496
497 memset(&fa, 0, sizeof(fa));
498 if (copy_from_user(&fa, (void __user *) arg, sizeof(fa)))
499 return -EFAULT;
500
501 return ovl_ioctl_set_flags(file, cmd, arg,
502 ovl_fsxflags_to_iflags(fa.fsx_xflags));
503}
504
505static long ovl_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
506{
507 long ret;
508
509 switch (cmd) {
510 case FS_IOC_GETFLAGS:
511 case FS_IOC_FSGETXATTR:
512 ret = ovl_real_ioctl(file, cmd, arg);
513 break;
514
515 case FS_IOC_SETFLAGS:
516 ret = ovl_ioctl_set_fsflags(file, cmd, arg);
517 break;
518
519 case FS_IOC_FSSETXATTR:
520 ret = ovl_ioctl_set_fsxflags(file, cmd, arg);
521 break;
522
523 default:
524 ret = -ENOTTY;
525 }
526
527 return ret;
528}
529
530static long ovl_compat_ioctl(struct file *file, unsigned int cmd,
531 unsigned long arg)
532{
533 switch (cmd) {
534 case FS_IOC32_GETFLAGS:
535 cmd = FS_IOC_GETFLAGS;
536 break;
537
538 case FS_IOC32_SETFLAGS:
539 cmd = FS_IOC_SETFLAGS;
540 break;
541
542 default:
543 return -ENOIOCTLCMD;
544 }
545
546 return ovl_ioctl(file, cmd, arg);
547}
548
549enum ovl_copyop {
550 OVL_COPY,
551 OVL_CLONE,
552 OVL_DEDUPE,
553};
554
555static loff_t ovl_copyfile(struct file *file_in, loff_t pos_in,
556 struct file *file_out, loff_t pos_out,
557 loff_t len, unsigned int flags, enum ovl_copyop op)
558{
559 struct inode *inode_out = file_inode(file_out);
560 struct fd real_in, real_out;
561 const struct cred *old_cred;
562 loff_t ret;
563
564 ret = ovl_real_fdget(file_out, &real_out);
565 if (ret)
566 return ret;
567
568 ret = ovl_real_fdget(file_in, &real_in);
569 if (ret) {
570 fdput(real_out);
571 return ret;
572 }
573
574 old_cred = ovl_override_creds(file_inode(file_out)->i_sb);
575 switch (op) {
576 case OVL_COPY:
577 ret = vfs_copy_file_range(real_in.file, pos_in,
578 real_out.file, pos_out, len, flags);
579 break;
580
581 case OVL_CLONE:
582 ret = vfs_clone_file_range(real_in.file, pos_in,
583 real_out.file, pos_out, len, flags);
584 break;
585
586 case OVL_DEDUPE:
587 ret = vfs_dedupe_file_range_one(real_in.file, pos_in,
588 real_out.file, pos_out, len,
589 flags);
590 break;
591 }
592 revert_creds(old_cred);
593
594
595 ovl_copyattr(ovl_inode_real(inode_out), inode_out);
596
597 fdput(real_in);
598 fdput(real_out);
599
600 return ret;
601}
602
603static ssize_t ovl_copy_file_range(struct file *file_in, loff_t pos_in,
604 struct file *file_out, loff_t pos_out,
605 size_t len, unsigned int flags)
606{
607 return ovl_copyfile(file_in, pos_in, file_out, pos_out, len, flags,
608 OVL_COPY);
609}
610
611static loff_t ovl_remap_file_range(struct file *file_in, loff_t pos_in,
612 struct file *file_out, loff_t pos_out,
613 loff_t len, unsigned int remap_flags)
614{
615 enum ovl_copyop op;
616
617 if (remap_flags & ~(REMAP_FILE_DEDUP | REMAP_FILE_ADVISORY))
618 return -EINVAL;
619
620 if (remap_flags & REMAP_FILE_DEDUP)
621 op = OVL_DEDUPE;
622 else
623 op = OVL_CLONE;
624
625
626
627
628
629 if (op == OVL_DEDUPE &&
630 (!ovl_inode_upper(file_inode(file_in)) ||
631 !ovl_inode_upper(file_inode(file_out))))
632 return -EPERM;
633
634 return ovl_copyfile(file_in, pos_in, file_out, pos_out, len,
635 remap_flags, op);
636}
637
638const struct file_operations ovl_file_operations = {
639 .open = ovl_open,
640 .release = ovl_release,
641 .llseek = ovl_llseek,
642 .read_iter = ovl_read_iter,
643 .write_iter = ovl_write_iter,
644 .fsync = ovl_fsync,
645 .mmap = ovl_mmap,
646 .fallocate = ovl_fallocate,
647 .fadvise = ovl_fadvise,
648 .unlocked_ioctl = ovl_ioctl,
649 .compat_ioctl = ovl_compat_ioctl,
650
651 .copy_file_range = ovl_copy_file_range,
652 .remap_file_range = ovl_remap_file_range,
653};
654
