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Linux/fs/read_write.c

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  1 // SPDX-License-Identifier: GPL-2.0
  2 /*
  3  *  linux/fs/read_write.c
  4  *
  5  *  Copyright (C) 1991, 1992  Linus Torvalds
  6  */
  7 
  8 #include <linux/slab.h>
  9 #include <linux/stat.h>
 10 #include <linux/sched/xacct.h>
 11 #include <linux/fcntl.h>
 12 #include <linux/file.h>
 13 #include <linux/uio.h>
 14 #include <linux/fsnotify.h>
 15 #include <linux/security.h>
 16 #include <linux/export.h>
 17 #include <linux/syscalls.h>
 18 #include <linux/pagemap.h>
 19 #include <linux/splice.h>
 20 #include <linux/compat.h>
 21 #include <linux/mount.h>
 22 #include <linux/fs.h>
 23 #include "internal.h"
 24 
 25 #include <linux/uaccess.h>
 26 #include <asm/unistd.h>
 27 
 28 const struct file_operations generic_ro_fops = {
 29         .llseek         = generic_file_llseek,
 30         .read_iter      = generic_file_read_iter,
 31         .mmap           = generic_file_readonly_mmap,
 32         .splice_read    = generic_file_splice_read,
 33 };
 34 
 35 EXPORT_SYMBOL(generic_ro_fops);
 36 
 37 static inline bool unsigned_offsets(struct file *file)
 38 {
 39         return file->f_mode & FMODE_UNSIGNED_OFFSET;
 40 }
 41 
 42 /**
 43  * vfs_setpos - update the file offset for lseek
 44  * @file:       file structure in question
 45  * @offset:     file offset to seek to
 46  * @maxsize:    maximum file size
 47  *
 48  * This is a low-level filesystem helper for updating the file offset to
 49  * the value specified by @offset if the given offset is valid and it is
 50  * not equal to the current file offset.
 51  *
 52  * Return the specified offset on success and -EINVAL on invalid offset.
 53  */
 54 loff_t vfs_setpos(struct file *file, loff_t offset, loff_t maxsize)
 55 {
 56         if (offset < 0 && !unsigned_offsets(file))
 57                 return -EINVAL;
 58         if (offset > maxsize)
 59                 return -EINVAL;
 60 
 61         if (offset != file->f_pos) {
 62                 file->f_pos = offset;
 63                 file->f_version = 0;
 64         }
 65         return offset;
 66 }
 67 EXPORT_SYMBOL(vfs_setpos);
 68 
 69 /**
 70  * generic_file_llseek_size - generic llseek implementation for regular files
 71  * @file:       file structure to seek on
 72  * @offset:     file offset to seek to
 73  * @whence:     type of seek
 74  * @size:       max size of this file in file system
 75  * @eof:        offset used for SEEK_END position
 76  *
 77  * This is a variant of generic_file_llseek that allows passing in a custom
 78  * maximum file size and a custom EOF position, for e.g. hashed directories
 79  *
 80  * Synchronization:
 81  * SEEK_SET and SEEK_END are unsynchronized (but atomic on 64bit platforms)
 82  * SEEK_CUR is synchronized against other SEEK_CURs, but not read/writes.
 83  * read/writes behave like SEEK_SET against seeks.
 84  */
 85 loff_t
 86 generic_file_llseek_size(struct file *file, loff_t offset, int whence,
 87                 loff_t maxsize, loff_t eof)
 88 {
 89         switch (whence) {
 90         case SEEK_END:
 91                 offset += eof;
 92                 break;
 93         case SEEK_CUR:
 94                 /*
 95                  * Here we special-case the lseek(fd, 0, SEEK_CUR)
 96                  * position-querying operation.  Avoid rewriting the "same"
 97                  * f_pos value back to the file because a concurrent read(),
 98                  * write() or lseek() might have altered it
 99                  */
100                 if (offset == 0)
101                         return file->f_pos;
102                 /*
103                  * f_lock protects against read/modify/write race with other
104                  * SEEK_CURs. Note that parallel writes and reads behave
105                  * like SEEK_SET.
106                  */
107                 spin_lock(&file->f_lock);
108                 offset = vfs_setpos(file, file->f_pos + offset, maxsize);
109                 spin_unlock(&file->f_lock);
110                 return offset;
111         case SEEK_DATA:
112                 /*
113                  * In the generic case the entire file is data, so as long as
114                  * offset isn't at the end of the file then the offset is data.
115                  */
116                 if ((unsigned long long)offset >= eof)
117                         return -ENXIO;
118                 break;
119         case SEEK_HOLE:
120                 /*
121                  * There is a virtual hole at the end of the file, so as long as
122                  * offset isn't i_size or larger, return i_size.
123                  */
124                 if ((unsigned long long)offset >= eof)
125                         return -ENXIO;
126                 offset = eof;
127                 break;
128         }
129 
130         return vfs_setpos(file, offset, maxsize);
131 }
132 EXPORT_SYMBOL(generic_file_llseek_size);
133 
134 /**
135  * generic_file_llseek - generic llseek implementation for regular files
136  * @file:       file structure to seek on
137  * @offset:     file offset to seek to
138  * @whence:     type of seek
139  *
140  * This is a generic implemenation of ->llseek useable for all normal local
141  * filesystems.  It just updates the file offset to the value specified by
142  * @offset and @whence.
143  */
144 loff_t generic_file_llseek(struct file *file, loff_t offset, int whence)
145 {
146         struct inode *inode = file->f_mapping->host;
147 
148         return generic_file_llseek_size(file, offset, whence,
149                                         inode->i_sb->s_maxbytes,
150                                         i_size_read(inode));
151 }
152 EXPORT_SYMBOL(generic_file_llseek);
153 
154 /**
155  * fixed_size_llseek - llseek implementation for fixed-sized devices
156  * @file:       file structure to seek on
157  * @offset:     file offset to seek to
158  * @whence:     type of seek
159  * @size:       size of the file
160  *
161  */
162 loff_t fixed_size_llseek(struct file *file, loff_t offset, int whence, loff_t size)
163 {
164         switch (whence) {
165         case SEEK_SET: case SEEK_CUR: case SEEK_END:
166                 return generic_file_llseek_size(file, offset, whence,
167                                                 size, size);
168         default:
169                 return -EINVAL;
170         }
171 }
172 EXPORT_SYMBOL(fixed_size_llseek);
173 
174 /**
175  * no_seek_end_llseek - llseek implementation for fixed-sized devices
176  * @file:       file structure to seek on
177  * @offset:     file offset to seek to
178  * @whence:     type of seek
179  *
180  */
181 loff_t no_seek_end_llseek(struct file *file, loff_t offset, int whence)
182 {
183         switch (whence) {
184         case SEEK_SET: case SEEK_CUR:
185                 return generic_file_llseek_size(file, offset, whence,
186                                                 OFFSET_MAX, 0);
187         default:
188                 return -EINVAL;
189         }
190 }
191 EXPORT_SYMBOL(no_seek_end_llseek);
192 
193 /**
194  * no_seek_end_llseek_size - llseek implementation for fixed-sized devices
195  * @file:       file structure to seek on
196  * @offset:     file offset to seek to
197  * @whence:     type of seek
198  * @size:       maximal offset allowed
199  *
200  */
201 loff_t no_seek_end_llseek_size(struct file *file, loff_t offset, int whence, loff_t size)
202 {
203         switch (whence) {
204         case SEEK_SET: case SEEK_CUR:
205                 return generic_file_llseek_size(file, offset, whence,
206                                                 size, 0);
207         default:
208                 return -EINVAL;
209         }
210 }
211 EXPORT_SYMBOL(no_seek_end_llseek_size);
212 
213 /**
214  * noop_llseek - No Operation Performed llseek implementation
215  * @file:       file structure to seek on
216  * @offset:     file offset to seek to
217  * @whence:     type of seek
218  *
219  * This is an implementation of ->llseek useable for the rare special case when
220  * userspace expects the seek to succeed but the (device) file is actually not
221  * able to perform the seek. In this case you use noop_llseek() instead of
222  * falling back to the default implementation of ->llseek.
223  */
224 loff_t noop_llseek(struct file *file, loff_t offset, int whence)
225 {
226         return file->f_pos;
227 }
228 EXPORT_SYMBOL(noop_llseek);
229 
230 loff_t no_llseek(struct file *file, loff_t offset, int whence)
231 {
232         return -ESPIPE;
233 }
234 EXPORT_SYMBOL(no_llseek);
235 
236 loff_t default_llseek(struct file *file, loff_t offset, int whence)
237 {
238         struct inode *inode = file_inode(file);
239         loff_t retval;
240 
241         inode_lock(inode);
242         switch (whence) {
243                 case SEEK_END:
244                         offset += i_size_read(inode);
245                         break;
246                 case SEEK_CUR:
247                         if (offset == 0) {
248                                 retval = file->f_pos;
249                                 goto out;
250                         }
251                         offset += file->f_pos;
252                         break;
253                 case SEEK_DATA:
254                         /*
255                          * In the generic case the entire file is data, so as
256                          * long as offset isn't at the end of the file then the
257                          * offset is data.
258                          */
259                         if (offset >= inode->i_size) {
260                                 retval = -ENXIO;
261                                 goto out;
262                         }
263                         break;
264                 case SEEK_HOLE:
265                         /*
266                          * There is a virtual hole at the end of the file, so
267                          * as long as offset isn't i_size or larger, return
268                          * i_size.
269                          */
270                         if (offset >= inode->i_size) {
271                                 retval = -ENXIO;
272                                 goto out;
273                         }
274                         offset = inode->i_size;
275                         break;
276         }
277         retval = -EINVAL;
278         if (offset >= 0 || unsigned_offsets(file)) {
279                 if (offset != file->f_pos) {
280                         file->f_pos = offset;
281                         file->f_version = 0;
282                 }
283                 retval = offset;
284         }
285 out:
286         inode_unlock(inode);
287         return retval;
288 }
289 EXPORT_SYMBOL(default_llseek);
290 
291 loff_t vfs_llseek(struct file *file, loff_t offset, int whence)
292 {
293         loff_t (*fn)(struct file *, loff_t, int);
294 
295         fn = no_llseek;
296         if (file->f_mode & FMODE_LSEEK) {
297                 if (file->f_op->llseek)
298                         fn = file->f_op->llseek;
299         }
300         return fn(file, offset, whence);
301 }
302 EXPORT_SYMBOL(vfs_llseek);
303 
304 off_t ksys_lseek(unsigned int fd, off_t offset, unsigned int whence)
305 {
306         off_t retval;
307         struct fd f = fdget_pos(fd);
308         if (!f.file)
309                 return -EBADF;
310 
311         retval = -EINVAL;
312         if (whence <= SEEK_MAX) {
313                 loff_t res = vfs_llseek(f.file, offset, whence);
314                 retval = res;
315                 if (res != (loff_t)retval)
316                         retval = -EOVERFLOW;    /* LFS: should only happen on 32 bit platforms */
317         }
318         fdput_pos(f);
319         return retval;
320 }
321 
322 SYSCALL_DEFINE3(lseek, unsigned int, fd, off_t, offset, unsigned int, whence)
323 {
324         return ksys_lseek(fd, offset, whence);
325 }
326 
327 #ifdef CONFIG_COMPAT
328 COMPAT_SYSCALL_DEFINE3(lseek, unsigned int, fd, compat_off_t, offset, unsigned int, whence)
329 {
330         return ksys_lseek(fd, offset, whence);
331 }
332 #endif
333 
334 #ifdef __ARCH_WANT_SYS_LLSEEK
335 SYSCALL_DEFINE5(llseek, unsigned int, fd, unsigned long, offset_high,
336                 unsigned long, offset_low, loff_t __user *, result,
337                 unsigned int, whence)
338 {
339         int retval;
340         struct fd f = fdget_pos(fd);
341         loff_t offset;
342 
343         if (!f.file)
344                 return -EBADF;
345 
346         retval = -EINVAL;
347         if (whence > SEEK_MAX)
348                 goto out_putf;
349 
350         offset = vfs_llseek(f.file, ((loff_t) offset_high << 32) | offset_low,
351                         whence);
352 
353         retval = (int)offset;
354         if (offset >= 0) {
355                 retval = -EFAULT;
356                 if (!copy_to_user(result, &offset, sizeof(offset)))
357                         retval = 0;
358         }
359 out_putf:
360         fdput_pos(f);
361         return retval;
362 }
363 #endif
364 
365 int rw_verify_area(int read_write, struct file *file, const loff_t *ppos, size_t count)
366 {
367         struct inode *inode;
368         loff_t pos;
369         int retval = -EINVAL;
370 
371         inode = file_inode(file);
372         if (unlikely((ssize_t) count < 0))
373                 return retval;
374         pos = *ppos;
375         if (unlikely(pos < 0)) {
376                 if (!unsigned_offsets(file))
377                         return retval;
378                 if (count >= -pos) /* both values are in 0..LLONG_MAX */
379                         return -EOVERFLOW;
380         } else if (unlikely((loff_t) (pos + count) < 0)) {
381                 if (!unsigned_offsets(file))
382                         return retval;
383         }
384 
385         if (unlikely(inode->i_flctx && mandatory_lock(inode))) {
386                 retval = locks_mandatory_area(inode, file, pos, pos + count - 1,
387                                 read_write == READ ? F_RDLCK : F_WRLCK);
388                 if (retval < 0)
389                         return retval;
390         }
391         return security_file_permission(file,
392                                 read_write == READ ? MAY_READ : MAY_WRITE);
393 }
394 
395 static ssize_t new_sync_read(struct file *filp, char __user *buf, size_t len, loff_t *ppos)
396 {
397         struct iovec iov = { .iov_base = buf, .iov_len = len };
398         struct kiocb kiocb;
399         struct iov_iter iter;
400         ssize_t ret;
401 
402         init_sync_kiocb(&kiocb, filp);
403         kiocb.ki_pos = *ppos;
404         iov_iter_init(&iter, READ, &iov, 1, len);
405 
406         ret = call_read_iter(filp, &kiocb, &iter);
407         BUG_ON(ret == -EIOCBQUEUED);
408         *ppos = kiocb.ki_pos;
409         return ret;
410 }
411 
412 ssize_t __vfs_read(struct file *file, char __user *buf, size_t count,
413                    loff_t *pos)
414 {
415         if (file->f_op->read)
416                 return file->f_op->read(file, buf, count, pos);
417         else if (file->f_op->read_iter)
418                 return new_sync_read(file, buf, count, pos);
419         else
420                 return -EINVAL;
421 }
422 
423 ssize_t kernel_read(struct file *file, void *buf, size_t count, loff_t *pos)
424 {
425         mm_segment_t old_fs;
426         ssize_t result;
427 
428         old_fs = get_fs();
429         set_fs(get_ds());
430         /* The cast to a user pointer is valid due to the set_fs() */
431         result = vfs_read(file, (void __user *)buf, count, pos);
432         set_fs(old_fs);
433         return result;
434 }
435 EXPORT_SYMBOL(kernel_read);
436 
437 ssize_t vfs_read(struct file *file, char __user *buf, size_t count, loff_t *pos)
438 {
439         ssize_t ret;
440 
441         if (!(file->f_mode & FMODE_READ))
442                 return -EBADF;
443         if (!(file->f_mode & FMODE_CAN_READ))
444                 return -EINVAL;
445         if (unlikely(!access_ok(VERIFY_WRITE, buf, count)))
446                 return -EFAULT;
447 
448         ret = rw_verify_area(READ, file, pos, count);
449         if (!ret) {
450                 if (count > MAX_RW_COUNT)
451                         count =  MAX_RW_COUNT;
452                 ret = __vfs_read(file, buf, count, pos);
453                 if (ret > 0) {
454                         fsnotify_access(file);
455                         add_rchar(current, ret);
456                 }
457                 inc_syscr(current);
458         }
459 
460         return ret;
461 }
462 
463 static ssize_t new_sync_write(struct file *filp, const char __user *buf, size_t len, loff_t *ppos)
464 {
465         struct iovec iov = { .iov_base = (void __user *)buf, .iov_len = len };
466         struct kiocb kiocb;
467         struct iov_iter iter;
468         ssize_t ret;
469 
470         init_sync_kiocb(&kiocb, filp);
471         kiocb.ki_pos = *ppos;
472         iov_iter_init(&iter, WRITE, &iov, 1, len);
473 
474         ret = call_write_iter(filp, &kiocb, &iter);
475         BUG_ON(ret == -EIOCBQUEUED);
476         if (ret > 0)
477                 *ppos = kiocb.ki_pos;
478         return ret;
479 }
480 
481 ssize_t __vfs_write(struct file *file, const char __user *p, size_t count,
482                     loff_t *pos)
483 {
484         if (file->f_op->write)
485                 return file->f_op->write(file, p, count, pos);
486         else if (file->f_op->write_iter)
487                 return new_sync_write(file, p, count, pos);
488         else
489                 return -EINVAL;
490 }
491 
492 ssize_t __kernel_write(struct file *file, const void *buf, size_t count, loff_t *pos)
493 {
494         mm_segment_t old_fs;
495         const char __user *p;
496         ssize_t ret;
497 
498         if (!(file->f_mode & FMODE_CAN_WRITE))
499                 return -EINVAL;
500 
501         old_fs = get_fs();
502         set_fs(get_ds());
503         p = (__force const char __user *)buf;
504         if (count > MAX_RW_COUNT)
505                 count =  MAX_RW_COUNT;
506         ret = __vfs_write(file, p, count, pos);
507         set_fs(old_fs);
508         if (ret > 0) {
509                 fsnotify_modify(file);
510                 add_wchar(current, ret);
511         }
512         inc_syscw(current);
513         return ret;
514 }
515 EXPORT_SYMBOL(__kernel_write);
516 
517 ssize_t kernel_write(struct file *file, const void *buf, size_t count,
518                             loff_t *pos)
519 {
520         mm_segment_t old_fs;
521         ssize_t res;
522 
523         old_fs = get_fs();
524         set_fs(get_ds());
525         /* The cast to a user pointer is valid due to the set_fs() */
526         res = vfs_write(file, (__force const char __user *)buf, count, pos);
527         set_fs(old_fs);
528 
529         return res;
530 }
531 EXPORT_SYMBOL(kernel_write);
532 
533 ssize_t vfs_write(struct file *file, const char __user *buf, size_t count, loff_t *pos)
534 {
535         ssize_t ret;
536 
537         if (!(file->f_mode & FMODE_WRITE))
538                 return -EBADF;
539         if (!(file->f_mode & FMODE_CAN_WRITE))
540                 return -EINVAL;
541         if (unlikely(!access_ok(VERIFY_READ, buf, count)))
542                 return -EFAULT;
543 
544         ret = rw_verify_area(WRITE, file, pos, count);
545         if (!ret) {
546                 if (count > MAX_RW_COUNT)
547                         count =  MAX_RW_COUNT;
548                 file_start_write(file);
549                 ret = __vfs_write(file, buf, count, pos);
550                 if (ret > 0) {
551                         fsnotify_modify(file);
552                         add_wchar(current, ret);
553                 }
554                 inc_syscw(current);
555                 file_end_write(file);
556         }
557 
558         return ret;
559 }
560 
561 static inline loff_t file_pos_read(struct file *file)
562 {
563         return file->f_pos;
564 }
565 
566 static inline void file_pos_write(struct file *file, loff_t pos)
567 {
568         file->f_pos = pos;
569 }
570 
571 ssize_t ksys_read(unsigned int fd, char __user *buf, size_t count)
572 {
573         struct fd f = fdget_pos(fd);
574         ssize_t ret = -EBADF;
575 
576         if (f.file) {
577                 loff_t pos = file_pos_read(f.file);
578                 ret = vfs_read(f.file, buf, count, &pos);
579                 if (ret >= 0)
580                         file_pos_write(f.file, pos);
581                 fdput_pos(f);
582         }
583         return ret;
584 }
585 
586 SYSCALL_DEFINE3(read, unsigned int, fd, char __user *, buf, size_t, count)
587 {
588         return ksys_read(fd, buf, count);
589 }
590 
591 ssize_t ksys_write(unsigned int fd, const char __user *buf, size_t count)
592 {
593         struct fd f = fdget_pos(fd);
594         ssize_t ret = -EBADF;
595 
596         if (f.file) {
597                 loff_t pos = file_pos_read(f.file);
598                 ret = vfs_write(f.file, buf, count, &pos);
599                 if (ret >= 0)
600                         file_pos_write(f.file, pos);
601                 fdput_pos(f);
602         }
603 
604         return ret;
605 }
606 
607 SYSCALL_DEFINE3(write, unsigned int, fd, const char __user *, buf,
608                 size_t, count)
609 {
610         return ksys_write(fd, buf, count);
611 }
612 
613 ssize_t ksys_pread64(unsigned int fd, char __user *buf, size_t count,
614                      loff_t pos)
615 {
616         struct fd f;
617         ssize_t ret = -EBADF;
618 
619         if (pos < 0)
620                 return -EINVAL;
621 
622         f = fdget(fd);
623         if (f.file) {
624                 ret = -ESPIPE;
625                 if (f.file->f_mode & FMODE_PREAD)
626                         ret = vfs_read(f.file, buf, count, &pos);
627                 fdput(f);
628         }
629 
630         return ret;
631 }
632 
633 SYSCALL_DEFINE4(pread64, unsigned int, fd, char __user *, buf,
634                         size_t, count, loff_t, pos)
635 {
636         return ksys_pread64(fd, buf, count, pos);
637 }
638 
639 ssize_t ksys_pwrite64(unsigned int fd, const char __user *buf,
640                       size_t count, loff_t pos)
641 {
642         struct fd f;
643         ssize_t ret = -EBADF;
644 
645         if (pos < 0)
646                 return -EINVAL;
647 
648         f = fdget(fd);
649         if (f.file) {
650                 ret = -ESPIPE;
651                 if (f.file->f_mode & FMODE_PWRITE)  
652                         ret = vfs_write(f.file, buf, count, &pos);
653                 fdput(f);
654         }
655 
656         return ret;
657 }
658 
659 SYSCALL_DEFINE4(pwrite64, unsigned int, fd, const char __user *, buf,
660                          size_t, count, loff_t, pos)
661 {
662         return ksys_pwrite64(fd, buf, count, pos);
663 }
664 
665 static ssize_t do_iter_readv_writev(struct file *filp, struct iov_iter *iter,
666                 loff_t *ppos, int type, rwf_t flags)
667 {
668         struct kiocb kiocb;
669         ssize_t ret;
670 
671         init_sync_kiocb(&kiocb, filp);
672         ret = kiocb_set_rw_flags(&kiocb, flags);
673         if (ret)
674                 return ret;
675         kiocb.ki_pos = *ppos;
676 
677         if (type == READ)
678                 ret = call_read_iter(filp, &kiocb, iter);
679         else
680                 ret = call_write_iter(filp, &kiocb, iter);
681         BUG_ON(ret == -EIOCBQUEUED);
682         *ppos = kiocb.ki_pos;
683         return ret;
684 }
685 
686 /* Do it by hand, with file-ops */
687 static ssize_t do_loop_readv_writev(struct file *filp, struct iov_iter *iter,
688                 loff_t *ppos, int type, rwf_t flags)
689 {
690         ssize_t ret = 0;
691 
692         if (flags & ~RWF_HIPRI)
693                 return -EOPNOTSUPP;
694 
695         while (iov_iter_count(iter)) {
696                 struct iovec iovec = iov_iter_iovec(iter);
697                 ssize_t nr;
698 
699                 if (type == READ) {
700                         nr = filp->f_op->read(filp, iovec.iov_base,
701                                               iovec.iov_len, ppos);
702                 } else {
703                         nr = filp->f_op->write(filp, iovec.iov_base,
704                                                iovec.iov_len, ppos);
705                 }
706 
707                 if (nr < 0) {
708                         if (!ret)
709                                 ret = nr;
710                         break;
711                 }
712                 ret += nr;
713                 if (nr != iovec.iov_len)
714                         break;
715                 iov_iter_advance(iter, nr);
716         }
717 
718         return ret;
719 }
720 
721 /* A write operation does a read from user space and vice versa */
722 #define vrfy_dir(type) ((type) == READ ? VERIFY_WRITE : VERIFY_READ)
723 
724 /**
725  * rw_copy_check_uvector() - Copy an array of &struct iovec from userspace
726  *     into the kernel and check that it is valid.
727  *
728  * @type: One of %CHECK_IOVEC_ONLY, %READ, or %WRITE.
729  * @uvector: Pointer to the userspace array.
730  * @nr_segs: Number of elements in userspace array.
731  * @fast_segs: Number of elements in @fast_pointer.
732  * @fast_pointer: Pointer to (usually small on-stack) kernel array.
733  * @ret_pointer: (output parameter) Pointer to a variable that will point to
734  *     either @fast_pointer, a newly allocated kernel array, or NULL,
735  *     depending on which array was used.
736  *
737  * This function copies an array of &struct iovec of @nr_segs from
738  * userspace into the kernel and checks that each element is valid (e.g.
739  * it does not point to a kernel address or cause overflow by being too
740  * large, etc.).
741  *
742  * As an optimization, the caller may provide a pointer to a small
743  * on-stack array in @fast_pointer, typically %UIO_FASTIOV elements long
744  * (the size of this array, or 0 if unused, should be given in @fast_segs).
745  *
746  * @ret_pointer will always point to the array that was used, so the
747  * caller must take care not to call kfree() on it e.g. in case the
748  * @fast_pointer array was used and it was allocated on the stack.
749  *
750  * Return: The total number of bytes covered by the iovec array on success
751  *   or a negative error code on error.
752  */
753 ssize_t rw_copy_check_uvector(int type, const struct iovec __user * uvector,
754                               unsigned long nr_segs, unsigned long fast_segs,
755                               struct iovec *fast_pointer,
756                               struct iovec **ret_pointer)
757 {
758         unsigned long seg;
759         ssize_t ret;
760         struct iovec *iov = fast_pointer;
761 
762         /*
763          * SuS says "The readv() function *may* fail if the iovcnt argument
764          * was less than or equal to 0, or greater than {IOV_MAX}.  Linux has
765          * traditionally returned zero for zero segments, so...
766          */
767         if (nr_segs == 0) {
768                 ret = 0;
769                 goto out;
770         }
771 
772         /*
773          * First get the "struct iovec" from user memory and
774          * verify all the pointers
775          */
776         if (nr_segs > UIO_MAXIOV) {
777                 ret = -EINVAL;
778                 goto out;
779         }
780         if (nr_segs > fast_segs) {
781                 iov = kmalloc(nr_segs*sizeof(struct iovec), GFP_KERNEL);
782                 if (iov == NULL) {
783                         ret = -ENOMEM;
784                         goto out;
785                 }
786         }
787         if (copy_from_user(iov, uvector, nr_segs*sizeof(*uvector))) {
788                 ret = -EFAULT;
789                 goto out;
790         }
791 
792         /*
793          * According to the Single Unix Specification we should return EINVAL
794          * if an element length is < 0 when cast to ssize_t or if the
795          * total length would overflow the ssize_t return value of the
796          * system call.
797          *
798          * Linux caps all read/write calls to MAX_RW_COUNT, and avoids the
799          * overflow case.
800          */
801         ret = 0;
802         for (seg = 0; seg < nr_segs; seg++) {
803                 void __user *buf = iov[seg].iov_base;
804                 ssize_t len = (ssize_t)iov[seg].iov_len;
805 
806                 /* see if we we're about to use an invalid len or if
807                  * it's about to overflow ssize_t */
808                 if (len < 0) {
809                         ret = -EINVAL;
810                         goto out;
811                 }
812                 if (type >= 0
813                     && unlikely(!access_ok(vrfy_dir(type), buf, len))) {
814                         ret = -EFAULT;
815                         goto out;
816                 }
817                 if (len > MAX_RW_COUNT - ret) {
818                         len = MAX_RW_COUNT - ret;
819                         iov[seg].iov_len = len;
820                 }
821                 ret += len;
822         }
823 out:
824         *ret_pointer = iov;
825         return ret;
826 }
827 
828 #ifdef CONFIG_COMPAT
829 ssize_t compat_rw_copy_check_uvector(int type,
830                 const struct compat_iovec __user *uvector, unsigned long nr_segs,
831                 unsigned long fast_segs, struct iovec *fast_pointer,
832                 struct iovec **ret_pointer)
833 {
834         compat_ssize_t tot_len;
835         struct iovec *iov = *ret_pointer = fast_pointer;
836         ssize_t ret = 0;
837         int seg;
838 
839         /*
840          * SuS says "The readv() function *may* fail if the iovcnt argument
841          * was less than or equal to 0, or greater than {IOV_MAX}.  Linux has
842          * traditionally returned zero for zero segments, so...
843          */
844         if (nr_segs == 0)
845                 goto out;
846 
847         ret = -EINVAL;
848         if (nr_segs > UIO_MAXIOV)
849                 goto out;
850         if (nr_segs > fast_segs) {
851                 ret = -ENOMEM;
852                 iov = kmalloc(nr_segs*sizeof(struct iovec), GFP_KERNEL);
853                 if (iov == NULL)
854                         goto out;
855         }
856         *ret_pointer = iov;
857 
858         ret = -EFAULT;
859         if (!access_ok(VERIFY_READ, uvector, nr_segs*sizeof(*uvector)))
860                 goto out;
861 
862         /*
863          * Single unix specification:
864          * We should -EINVAL if an element length is not >= 0 and fitting an
865          * ssize_t.
866          *
867          * In Linux, the total length is limited to MAX_RW_COUNT, there is
868          * no overflow possibility.
869          */
870         tot_len = 0;
871         ret = -EINVAL;
872         for (seg = 0; seg < nr_segs; seg++) {
873                 compat_uptr_t buf;
874                 compat_ssize_t len;
875 
876                 if (__get_user(len, &uvector->iov_len) ||
877                    __get_user(buf, &uvector->iov_base)) {
878                         ret = -EFAULT;
879                         goto out;
880                 }
881                 if (len < 0)    /* size_t not fitting in compat_ssize_t .. */
882                         goto out;
883                 if (type >= 0 &&
884                     !access_ok(vrfy_dir(type), compat_ptr(buf), len)) {
885                         ret = -EFAULT;
886                         goto out;
887                 }
888                 if (len > MAX_RW_COUNT - tot_len)
889                         len = MAX_RW_COUNT - tot_len;
890                 tot_len += len;
891                 iov->iov_base = compat_ptr(buf);
892                 iov->iov_len = (compat_size_t) len;
893                 uvector++;
894                 iov++;
895         }
896         ret = tot_len;
897 
898 out:
899         return ret;
900 }
901 #endif
902 
903 static ssize_t do_iter_read(struct file *file, struct iov_iter *iter,
904                 loff_t *pos, rwf_t flags)
905 {
906         size_t tot_len;
907         ssize_t ret = 0;
908 
909         if (!(file->f_mode & FMODE_READ))
910                 return -EBADF;
911         if (!(file->f_mode & FMODE_CAN_READ))
912                 return -EINVAL;
913 
914         tot_len = iov_iter_count(iter);
915         if (!tot_len)
916                 goto out;
917         ret = rw_verify_area(READ, file, pos, tot_len);
918         if (ret < 0)
919                 return ret;
920 
921         if (file->f_op->read_iter)
922                 ret = do_iter_readv_writev(file, iter, pos, READ, flags);
923         else
924                 ret = do_loop_readv_writev(file, iter, pos, READ, flags);
925 out:
926         if (ret >= 0)
927                 fsnotify_access(file);
928         return ret;
929 }
930 
931 ssize_t vfs_iter_read(struct file *file, struct iov_iter *iter, loff_t *ppos,
932                 rwf_t flags)
933 {
934         if (!file->f_op->read_iter)
935                 return -EINVAL;
936         return do_iter_read(file, iter, ppos, flags);
937 }
938 EXPORT_SYMBOL(vfs_iter_read);
939 
940 static ssize_t do_iter_write(struct file *file, struct iov_iter *iter,
941                 loff_t *pos, rwf_t flags)
942 {
943         size_t tot_len;
944         ssize_t ret = 0;
945 
946         if (!(file->f_mode & FMODE_WRITE))
947                 return -EBADF;
948         if (!(file->f_mode & FMODE_CAN_WRITE))
949                 return -EINVAL;
950 
951         tot_len = iov_iter_count(iter);
952         if (!tot_len)
953                 return 0;
954         ret = rw_verify_area(WRITE, file, pos, tot_len);
955         if (ret < 0)
956                 return ret;
957 
958         if (file->f_op->write_iter)
959                 ret = do_iter_readv_writev(file, iter, pos, WRITE, flags);
960         else
961                 ret = do_loop_readv_writev(file, iter, pos, WRITE, flags);
962         if (ret > 0)
963                 fsnotify_modify(file);
964         return ret;
965 }
966 
967 ssize_t vfs_iter_write(struct file *file, struct iov_iter *iter, loff_t *ppos,
968                 rwf_t flags)
969 {
970         if (!file->f_op->write_iter)
971                 return -EINVAL;
972         return do_iter_write(file, iter, ppos, flags);
973 }
974 EXPORT_SYMBOL(vfs_iter_write);
975 
976 ssize_t vfs_readv(struct file *file, const struct iovec __user *vec,
977                   unsigned long vlen, loff_t *pos, rwf_t flags)
978 {
979         struct iovec iovstack[UIO_FASTIOV];
980         struct iovec *iov = iovstack;
981         struct iov_iter iter;
982         ssize_t ret;
983 
984         ret = import_iovec(READ, vec, vlen, ARRAY_SIZE(iovstack), &iov, &iter);
985         if (ret >= 0) {
986                 ret = do_iter_read(file, &iter, pos, flags);
987                 kfree(iov);
988         }
989 
990         return ret;
991 }
992 
993 static ssize_t vfs_writev(struct file *file, const struct iovec __user *vec,
994                    unsigned long vlen, loff_t *pos, rwf_t flags)
995 {
996         struct iovec iovstack[UIO_FASTIOV];
997         struct iovec *iov = iovstack;
998         struct iov_iter iter;
999         ssize_t ret;
1000 
1001         ret = import_iovec(WRITE, vec, vlen, ARRAY_SIZE(iovstack), &iov, &iter);
1002         if (ret >= 0) {
1003                 file_start_write(file);
1004                 ret = do_iter_write(file, &iter, pos, flags);
1005                 file_end_write(file);
1006                 kfree(iov);
1007         }
1008         return ret;
1009 }
1010 
1011 static ssize_t do_readv(unsigned long fd, const struct iovec __user *vec,
1012                         unsigned long vlen, rwf_t flags)
1013 {
1014         struct fd f = fdget_pos(fd);
1015         ssize_t ret = -EBADF;
1016 
1017         if (f.file) {
1018                 loff_t pos = file_pos_read(f.file);
1019                 ret = vfs_readv(f.file, vec, vlen, &pos, flags);
1020                 if (ret >= 0)
1021                         file_pos_write(f.file, pos);
1022                 fdput_pos(f);
1023         }
1024 
1025         if (ret > 0)
1026                 add_rchar(current, ret);
1027         inc_syscr(current);
1028         return ret;
1029 }
1030 
1031 static ssize_t do_writev(unsigned long fd, const struct iovec __user *vec,
1032                          unsigned long vlen, rwf_t flags)
1033 {
1034         struct fd f = fdget_pos(fd);
1035         ssize_t ret = -EBADF;
1036 
1037         if (f.file) {
1038                 loff_t pos = file_pos_read(f.file);
1039                 ret = vfs_writev(f.file, vec, vlen, &pos, flags);
1040                 if (ret >= 0)
1041                         file_pos_write(f.file, pos);
1042                 fdput_pos(f);
1043         }
1044 
1045         if (ret > 0)
1046                 add_wchar(current, ret);
1047         inc_syscw(current);
1048         return ret;
1049 }
1050 
1051 static inline loff_t pos_from_hilo(unsigned long high, unsigned long low)
1052 {
1053 #define HALF_LONG_BITS (BITS_PER_LONG / 2)
1054         return (((loff_t)high << HALF_LONG_BITS) << HALF_LONG_BITS) | low;
1055 }
1056 
1057 static ssize_t do_preadv(unsigned long fd, const struct iovec __user *vec,
1058                          unsigned long vlen, loff_t pos, rwf_t flags)
1059 {
1060         struct fd f;
1061         ssize_t ret = -EBADF;
1062 
1063         if (pos < 0)
1064                 return -EINVAL;
1065 
1066         f = fdget(fd);
1067         if (f.file) {
1068                 ret = -ESPIPE;
1069                 if (f.file->f_mode & FMODE_PREAD)
1070                         ret = vfs_readv(f.file, vec, vlen, &pos, flags);
1071                 fdput(f);
1072         }
1073 
1074         if (ret > 0)
1075                 add_rchar(current, ret);
1076         inc_syscr(current);
1077         return ret;
1078 }
1079 
1080 static ssize_t do_pwritev(unsigned long fd, const struct iovec __user *vec,
1081                           unsigned long vlen, loff_t pos, rwf_t flags)
1082 {
1083         struct fd f;
1084         ssize_t ret = -EBADF;
1085 
1086         if (pos < 0)
1087                 return -EINVAL;
1088 
1089         f = fdget(fd);
1090         if (f.file) {
1091                 ret = -ESPIPE;
1092                 if (f.file->f_mode & FMODE_PWRITE)
1093                         ret = vfs_writev(f.file, vec, vlen, &pos, flags);
1094                 fdput(f);
1095         }
1096 
1097         if (ret > 0)
1098                 add_wchar(current, ret);
1099         inc_syscw(current);
1100         return ret;
1101 }
1102 
1103 SYSCALL_DEFINE3(readv, unsigned long, fd, const struct iovec __user *, vec,
1104                 unsigned long, vlen)
1105 {
1106         return do_readv(fd, vec, vlen, 0);
1107 }
1108 
1109 SYSCALL_DEFINE3(writev, unsigned long, fd, const struct iovec __user *, vec,
1110                 unsigned long, vlen)
1111 {
1112         return do_writev(fd, vec, vlen, 0);
1113 }
1114 
1115 SYSCALL_DEFINE5(preadv, unsigned long, fd, const struct iovec __user *, vec,
1116                 unsigned long, vlen, unsigned long, pos_l, unsigned long, pos_h)
1117 {
1118         loff_t pos = pos_from_hilo(pos_h, pos_l);
1119 
1120         return do_preadv(fd, vec, vlen, pos, 0);
1121 }
1122 
1123 SYSCALL_DEFINE6(preadv2, unsigned long, fd, const struct iovec __user *, vec,
1124                 unsigned long, vlen, unsigned long, pos_l, unsigned long, pos_h,
1125                 rwf_t, flags)
1126 {
1127         loff_t pos = pos_from_hilo(pos_h, pos_l);
1128 
1129         if (pos == -1)
1130                 return do_readv(fd, vec, vlen, flags);
1131 
1132         return do_preadv(fd, vec, vlen, pos, flags);
1133 }
1134 
1135 SYSCALL_DEFINE5(pwritev, unsigned long, fd, const struct iovec __user *, vec,
1136                 unsigned long, vlen, unsigned long, pos_l, unsigned long, pos_h)
1137 {
1138         loff_t pos = pos_from_hilo(pos_h, pos_l);
1139 
1140         return do_pwritev(fd, vec, vlen, pos, 0);
1141 }
1142 
1143 SYSCALL_DEFINE6(pwritev2, unsigned long, fd, const struct iovec __user *, vec,
1144                 unsigned long, vlen, unsigned long, pos_l, unsigned long, pos_h,
1145                 rwf_t, flags)
1146 {
1147         loff_t pos = pos_from_hilo(pos_h, pos_l);
1148 
1149         if (pos == -1)
1150                 return do_writev(fd, vec, vlen, flags);
1151 
1152         return do_pwritev(fd, vec, vlen, pos, flags);
1153 }
1154 
1155 #ifdef CONFIG_COMPAT
1156 static size_t compat_readv(struct file *file,
1157                            const struct compat_iovec __user *vec,
1158                            unsigned long vlen, loff_t *pos, rwf_t flags)
1159 {
1160         struct iovec iovstack[UIO_FASTIOV];
1161         struct iovec *iov = iovstack;
1162         struct iov_iter iter;
1163         ssize_t ret;
1164 
1165         ret = compat_import_iovec(READ, vec, vlen, UIO_FASTIOV, &iov, &iter);
1166         if (ret >= 0) {
1167                 ret = do_iter_read(file, &iter, pos, flags);
1168                 kfree(iov);
1169         }
1170         if (ret > 0)
1171                 add_rchar(current, ret);
1172         inc_syscr(current);
1173         return ret;
1174 }
1175 
1176 static size_t do_compat_readv(compat_ulong_t fd,
1177                                  const struct compat_iovec __user *vec,
1178                                  compat_ulong_t vlen, rwf_t flags)
1179 {
1180         struct fd f = fdget_pos(fd);
1181         ssize_t ret;
1182         loff_t pos;
1183 
1184         if (!f.file)
1185                 return -EBADF;
1186         pos = f.file->f_pos;
1187         ret = compat_readv(f.file, vec, vlen, &pos, flags);
1188         if (ret >= 0)
1189                 f.file->f_pos = pos;
1190         fdput_pos(f);
1191         return ret;
1192 
1193 }
1194 
1195 COMPAT_SYSCALL_DEFINE3(readv, compat_ulong_t, fd,
1196                 const struct compat_iovec __user *,vec,
1197                 compat_ulong_t, vlen)
1198 {
1199         return do_compat_readv(fd, vec, vlen, 0);
1200 }
1201 
1202 static long do_compat_preadv64(unsigned long fd,
1203                                   const struct compat_iovec __user *vec,
1204                                   unsigned long vlen, loff_t pos, rwf_t flags)
1205 {
1206         struct fd f;
1207         ssize_t ret;
1208 
1209         if (pos < 0)
1210                 return -EINVAL;
1211         f = fdget(fd);
1212         if (!f.file)
1213                 return -EBADF;
1214         ret = -ESPIPE;
1215         if (f.file->f_mode & FMODE_PREAD)
1216                 ret = compat_readv(f.file, vec, vlen, &pos, flags);
1217         fdput(f);
1218         return ret;
1219 }
1220 
1221 #ifdef __ARCH_WANT_COMPAT_SYS_PREADV64
1222 COMPAT_SYSCALL_DEFINE4(preadv64, unsigned long, fd,
1223                 const struct compat_iovec __user *,vec,
1224                 unsigned long, vlen, loff_t, pos)
1225 {
1226         return do_compat_preadv64(fd, vec, vlen, pos, 0);
1227 }
1228 #endif
1229 
1230 COMPAT_SYSCALL_DEFINE5(preadv, compat_ulong_t, fd,
1231                 const struct compat_iovec __user *,vec,
1232                 compat_ulong_t, vlen, u32, pos_low, u32, pos_high)
1233 {
1234         loff_t pos = ((loff_t)pos_high << 32) | pos_low;
1235 
1236         return do_compat_preadv64(fd, vec, vlen, pos, 0);
1237 }
1238 
1239 #ifdef __ARCH_WANT_COMPAT_SYS_PREADV64V2
1240 COMPAT_SYSCALL_DEFINE5(preadv64v2, unsigned long, fd,
1241                 const struct compat_iovec __user *,vec,
1242                 unsigned long, vlen, loff_t, pos, rwf_t, flags)
1243 {
1244         return do_compat_preadv64(fd, vec, vlen, pos, flags);
1245 }
1246 #endif
1247 
1248 COMPAT_SYSCALL_DEFINE6(preadv2, compat_ulong_t, fd,
1249                 const struct compat_iovec __user *,vec,
1250                 compat_ulong_t, vlen, u32, pos_low, u32, pos_high,
1251                 rwf_t, flags)
1252 {
1253         loff_t pos = ((loff_t)pos_high << 32) | pos_low;
1254 
1255         if (pos == -1)
1256                 return do_compat_readv(fd, vec, vlen, flags);
1257 
1258         return do_compat_preadv64(fd, vec, vlen, pos, flags);
1259 }
1260 
1261 static size_t compat_writev(struct file *file,
1262                             const struct compat_iovec __user *vec,
1263                             unsigned long vlen, loff_t *pos, rwf_t flags)
1264 {
1265         struct iovec iovstack[UIO_FASTIOV];
1266         struct iovec *iov = iovstack;
1267         struct iov_iter iter;
1268         ssize_t ret;
1269 
1270         ret = compat_import_iovec(WRITE, vec, vlen, UIO_FASTIOV, &iov, &iter);
1271         if (ret >= 0) {
1272                 file_start_write(file);
1273                 ret = do_iter_write(file, &iter, pos, flags);
1274                 file_end_write(file);
1275                 kfree(iov);
1276         }
1277         if (ret > 0)
1278                 add_wchar(current, ret);
1279         inc_syscw(current);
1280         return ret;
1281 }
1282 
1283 static size_t do_compat_writev(compat_ulong_t fd,
1284                                   const struct compat_iovec __user* vec,
1285                                   compat_ulong_t vlen, rwf_t flags)
1286 {
1287         struct fd f = fdget_pos(fd);
1288         ssize_t ret;
1289         loff_t pos;
1290 
1291         if (!f.file)
1292                 return -EBADF;
1293         pos = f.file->f_pos;
1294         ret = compat_writev(f.file, vec, vlen, &pos, flags);
1295         if (ret >= 0)
1296                 f.file->f_pos = pos;
1297         fdput_pos(f);
1298         return ret;
1299 }
1300 
1301 COMPAT_SYSCALL_DEFINE3(writev, compat_ulong_t, fd,
1302                 const struct compat_iovec __user *, vec,
1303                 compat_ulong_t, vlen)
1304 {
1305         return do_compat_writev(fd, vec, vlen, 0);
1306 }
1307 
1308 static long do_compat_pwritev64(unsigned long fd,
1309                                    const struct compat_iovec __user *vec,
1310                                    unsigned long vlen, loff_t pos, rwf_t flags)
1311 {
1312         struct fd f;
1313         ssize_t ret;
1314 
1315         if (pos < 0)
1316                 return -EINVAL;
1317         f = fdget(fd);
1318         if (!f.file)
1319                 return -EBADF;
1320         ret = -ESPIPE;
1321         if (f.file->f_mode & FMODE_PWRITE)
1322                 ret = compat_writev(f.file, vec, vlen, &pos, flags);
1323         fdput(f);
1324         return ret;
1325 }
1326 
1327 #ifdef __ARCH_WANT_COMPAT_SYS_PWRITEV64
1328 COMPAT_SYSCALL_DEFINE4(pwritev64, unsigned long, fd,
1329                 const struct compat_iovec __user *,vec,
1330                 unsigned long, vlen, loff_t, pos)
1331 {
1332         return do_compat_pwritev64(fd, vec, vlen, pos, 0);
1333 }
1334 #endif
1335 
1336 COMPAT_SYSCALL_DEFINE5(pwritev, compat_ulong_t, fd,
1337                 const struct compat_iovec __user *,vec,
1338                 compat_ulong_t, vlen, u32, pos_low, u32, pos_high)
1339 {
1340         loff_t pos = ((loff_t)pos_high << 32) | pos_low;
1341 
1342         return do_compat_pwritev64(fd, vec, vlen, pos, 0);
1343 }
1344 
1345 #ifdef __ARCH_WANT_COMPAT_SYS_PWRITEV64V2
1346 COMPAT_SYSCALL_DEFINE5(pwritev64v2, unsigned long, fd,
1347                 const struct compat_iovec __user *,vec,
1348                 unsigned long, vlen, loff_t, pos, rwf_t, flags)
1349 {
1350         return do_compat_pwritev64(fd, vec, vlen, pos, flags);
1351 }
1352 #endif
1353 
1354 COMPAT_SYSCALL_DEFINE6(pwritev2, compat_ulong_t, fd,
1355                 const struct compat_iovec __user *,vec,
1356                 compat_ulong_t, vlen, u32, pos_low, u32, pos_high, rwf_t, flags)
1357 {
1358         loff_t pos = ((loff_t)pos_high << 32) | pos_low;
1359 
1360         if (pos == -1)
1361                 return do_compat_writev(fd, vec, vlen, flags);
1362 
1363         return do_compat_pwritev64(fd, vec, vlen, pos, flags);
1364 }
1365 
1366 #endif
1367 
1368 static ssize_t do_sendfile(int out_fd, int in_fd, loff_t *ppos,
1369                            size_t count, loff_t max)
1370 {
1371         struct fd in, out;
1372         struct inode *in_inode, *out_inode;
1373         loff_t pos;
1374         loff_t out_pos;
1375         ssize_t retval;
1376         int fl;
1377 
1378         /*
1379          * Get input file, and verify that it is ok..
1380          */
1381         retval = -EBADF;
1382         in = fdget(in_fd);
1383         if (!in.file)
1384                 goto out;
1385         if (!(in.file->f_mode & FMODE_READ))
1386                 goto fput_in;
1387         retval = -ESPIPE;
1388         if (!ppos) {
1389                 pos = in.file->f_pos;
1390         } else {
1391                 pos = *ppos;
1392                 if (!(in.file->f_mode & FMODE_PREAD))
1393                         goto fput_in;
1394         }
1395         retval = rw_verify_area(READ, in.file, &pos, count);
1396         if (retval < 0)
1397                 goto fput_in;
1398         if (count > MAX_RW_COUNT)
1399                 count =  MAX_RW_COUNT;
1400 
1401         /*
1402          * Get output file, and verify that it is ok..
1403          */
1404         retval = -EBADF;
1405         out = fdget(out_fd);
1406         if (!out.file)
1407                 goto fput_in;
1408         if (!(out.file->f_mode & FMODE_WRITE))
1409                 goto fput_out;
1410         retval = -EINVAL;
1411         in_inode = file_inode(in.file);
1412         out_inode = file_inode(out.file);
1413         out_pos = out.file->f_pos;
1414         retval = rw_verify_area(WRITE, out.file, &out_pos, count);
1415         if (retval < 0)
1416                 goto fput_out;
1417 
1418         if (!max)
1419                 max = min(in_inode->i_sb->s_maxbytes, out_inode->i_sb->s_maxbytes);
1420 
1421         if (unlikely(pos + count > max)) {
1422                 retval = -EOVERFLOW;
1423                 if (pos >= max)
1424                         goto fput_out;
1425                 count = max - pos;
1426         }
1427 
1428         fl = 0;
1429 #if 0
1430         /*
1431          * We need to debate whether we can enable this or not. The
1432          * man page documents EAGAIN return for the output at least,
1433          * and the application is arguably buggy if it doesn't expect
1434          * EAGAIN on a non-blocking file descriptor.
1435          */
1436         if (in.file->f_flags & O_NONBLOCK)
1437                 fl = SPLICE_F_NONBLOCK;
1438 #endif
1439         file_start_write(out.file);
1440         retval = do_splice_direct(in.file, &pos, out.file, &out_pos, count, fl);
1441         file_end_write(out.file);
1442 
1443         if (retval > 0) {
1444                 add_rchar(current, retval);
1445                 add_wchar(current, retval);
1446                 fsnotify_access(in.file);
1447                 fsnotify_modify(out.file);
1448                 out.file->f_pos = out_pos;
1449                 if (ppos)
1450                         *ppos = pos;
1451                 else
1452                         in.file->f_pos = pos;
1453         }
1454 
1455         inc_syscr(current);
1456         inc_syscw(current);
1457         if (pos > max)
1458                 retval = -EOVERFLOW;
1459 
1460 fput_out:
1461         fdput(out);
1462 fput_in:
1463         fdput(in);
1464 out:
1465         return retval;
1466 }
1467 
1468 SYSCALL_DEFINE4(sendfile, int, out_fd, int, in_fd, off_t __user *, offset, size_t, count)
1469 {
1470         loff_t pos;
1471         off_t off;
1472         ssize_t ret;
1473 
1474         if (offset) {
1475                 if (unlikely(get_user(off, offset)))
1476                         return -EFAULT;
1477                 pos = off;
1478                 ret = do_sendfile(out_fd, in_fd, &pos, count, MAX_NON_LFS);
1479                 if (unlikely(put_user(pos, offset)))
1480                         return -EFAULT;
1481                 return ret;
1482         }
1483 
1484         return do_sendfile(out_fd, in_fd, NULL, count, 0);
1485 }
1486 
1487 SYSCALL_DEFINE4(sendfile64, int, out_fd, int, in_fd, loff_t __user *, offset, size_t, count)
1488 {
1489         loff_t pos;
1490         ssize_t ret;
1491 
1492         if (offset) {
1493                 if (unlikely(copy_from_user(&pos, offset, sizeof(loff_t))))
1494                         return -EFAULT;
1495                 ret = do_sendfile(out_fd, in_fd, &pos, count, 0);
1496                 if (unlikely(put_user(pos, offset)))
1497                         return -EFAULT;
1498                 return ret;
1499         }
1500 
1501         return do_sendfile(out_fd, in_fd, NULL, count, 0);
1502 }
1503 
1504 #ifdef CONFIG_COMPAT
1505 COMPAT_SYSCALL_DEFINE4(sendfile, int, out_fd, int, in_fd,
1506                 compat_off_t __user *, offset, compat_size_t, count)
1507 {
1508         loff_t pos;
1509         off_t off;
1510         ssize_t ret;
1511 
1512         if (offset) {
1513                 if (unlikely(get_user(off, offset)))
1514                         return -EFAULT;
1515                 pos = off;
1516                 ret = do_sendfile(out_fd, in_fd, &pos, count, MAX_NON_LFS);
1517                 if (unlikely(put_user(pos, offset)))
1518                         return -EFAULT;
1519                 return ret;
1520         }
1521 
1522         return do_sendfile(out_fd, in_fd, NULL, count, 0);
1523 }
1524 
1525 COMPAT_SYSCALL_DEFINE4(sendfile64, int, out_fd, int, in_fd,
1526                 compat_loff_t __user *, offset, compat_size_t, count)
1527 {
1528         loff_t pos;
1529         ssize_t ret;
1530 
1531         if (offset) {
1532                 if (unlikely(copy_from_user(&pos, offset, sizeof(loff_t))))
1533                         return -EFAULT;
1534                 ret = do_sendfile(out_fd, in_fd, &pos, count, 0);
1535                 if (unlikely(put_user(pos, offset)))
1536                         return -EFAULT;
1537                 return ret;
1538         }
1539 
1540         return do_sendfile(out_fd, in_fd, NULL, count, 0);
1541 }
1542 #endif
1543 
1544 /*
1545  * copy_file_range() differs from regular file read and write in that it
1546  * specifically allows return partial success.  When it does so is up to
1547  * the copy_file_range method.
1548  */
1549 ssize_t vfs_copy_file_range(struct file *file_in, loff_t pos_in,
1550                             struct file *file_out, loff_t pos_out,
1551                             size_t len, unsigned int flags)
1552 {
1553         struct inode *inode_in = file_inode(file_in);
1554         struct inode *inode_out = file_inode(file_out);
1555         ssize_t ret;
1556 
1557         if (flags != 0)
1558                 return -EINVAL;
1559 
1560         if (S_ISDIR(inode_in->i_mode) || S_ISDIR(inode_out->i_mode))
1561                 return -EISDIR;
1562         if (!S_ISREG(inode_in->i_mode) || !S_ISREG(inode_out->i_mode))
1563                 return -EINVAL;
1564 
1565         ret = rw_verify_area(READ, file_in, &pos_in, len);
1566         if (unlikely(ret))
1567                 return ret;
1568 
1569         ret = rw_verify_area(WRITE, file_out, &pos_out, len);
1570         if (unlikely(ret))
1571                 return ret;
1572 
1573         if (!(file_in->f_mode & FMODE_READ) ||
1574             !(file_out->f_mode & FMODE_WRITE) ||
1575             (file_out->f_flags & O_APPEND))
1576                 return -EBADF;
1577 
1578         /* this could be relaxed once a method supports cross-fs copies */
1579         if (inode_in->i_sb != inode_out->i_sb)
1580                 return -EXDEV;
1581 
1582         if (len == 0)
1583                 return 0;
1584 
1585         file_start_write(file_out);
1586 
1587         /*
1588          * Try cloning first, this is supported by more file systems, and
1589          * more efficient if both clone and copy are supported (e.g. NFS).
1590          */
1591         if (file_in->f_op->clone_file_range) {
1592                 ret = file_in->f_op->clone_file_range(file_in, pos_in,
1593                                 file_out, pos_out, len);
1594                 if (ret == 0) {
1595                         ret = len;
1596                         goto done;
1597                 }
1598         }
1599 
1600         if (file_out->f_op->copy_file_range) {
1601                 ret = file_out->f_op->copy_file_range(file_in, pos_in, file_out,
1602                                                       pos_out, len, flags);
1603                 if (ret != -EOPNOTSUPP)
1604                         goto done;
1605         }
1606 
1607         ret = do_splice_direct(file_in, &pos_in, file_out, &pos_out,
1608                         len > MAX_RW_COUNT ? MAX_RW_COUNT : len, 0);
1609 
1610 done:
1611         if (ret > 0) {
1612                 fsnotify_access(file_in);
1613                 add_rchar(current, ret);
1614                 fsnotify_modify(file_out);
1615                 add_wchar(current, ret);
1616         }
1617 
1618         inc_syscr(current);
1619         inc_syscw(current);
1620 
1621         file_end_write(file_out);
1622 
1623         return ret;
1624 }
1625 EXPORT_SYMBOL(vfs_copy_file_range);
1626 
1627 SYSCALL_DEFINE6(copy_file_range, int, fd_in, loff_t __user *, off_in,
1628                 int, fd_out, loff_t __user *, off_out,
1629                 size_t, len, unsigned int, flags)
1630 {
1631         loff_t pos_in;
1632         loff_t pos_out;
1633         struct fd f_in;
1634         struct fd f_out;
1635         ssize_t ret = -EBADF;
1636 
1637         f_in = fdget(fd_in);
1638         if (!f_in.file)
1639                 goto out2;
1640 
1641         f_out = fdget(fd_out);
1642         if (!f_out.file)
1643                 goto out1;
1644 
1645         ret = -EFAULT;
1646         if (off_in) {
1647                 if (copy_from_user(&pos_in, off_in, sizeof(loff_t)))
1648                         goto out;
1649         } else {
1650                 pos_in = f_in.file->f_pos;
1651         }
1652 
1653         if (off_out) {
1654                 if (copy_from_user(&pos_out, off_out, sizeof(loff_t)))
1655                         goto out;
1656         } else {
1657                 pos_out = f_out.file->f_pos;
1658         }
1659 
1660         ret = vfs_copy_file_range(f_in.file, pos_in, f_out.file, pos_out, len,
1661                                   flags);
1662         if (ret > 0) {
1663                 pos_in += ret;
1664                 pos_out += ret;
1665 
1666                 if (off_in) {
1667                         if (copy_to_user(off_in, &pos_in, sizeof(loff_t)))
1668                                 ret = -EFAULT;
1669                 } else {
1670                         f_in.file->f_pos = pos_in;
1671                 }
1672 
1673                 if (off_out) {
1674                         if (copy_to_user(off_out, &pos_out, sizeof(loff_t)))
1675                                 ret = -EFAULT;
1676                 } else {
1677                         f_out.file->f_pos = pos_out;
1678                 }
1679         }
1680 
1681 out:
1682         fdput(f_out);
1683 out1:
1684         fdput(f_in);
1685 out2:
1686         return ret;
1687 }
1688 
1689 static int clone_verify_area(struct file *file, loff_t pos, u64 len, bool write)
1690 {
1691         struct inode *inode = file_inode(file);
1692 
1693         if (unlikely(pos < 0))
1694                 return -EINVAL;
1695 
1696          if (unlikely((loff_t) (pos + len) < 0))
1697                 return -EINVAL;
1698 
1699         if (unlikely(inode->i_flctx && mandatory_lock(inode))) {
1700                 loff_t end = len ? pos + len - 1 : OFFSET_MAX;
1701                 int retval;
1702 
1703                 retval = locks_mandatory_area(inode, file, pos, end,
1704                                 write ? F_WRLCK : F_RDLCK);
1705                 if (retval < 0)
1706                         return retval;
1707         }
1708 
1709         return security_file_permission(file, write ? MAY_WRITE : MAY_READ);
1710 }
1711 
1712 /*
1713  * Check that the two inodes are eligible for cloning, the ranges make
1714  * sense, and then flush all dirty data.  Caller must ensure that the
1715  * inodes have been locked against any other modifications.
1716  *
1717  * Returns: 0 for "nothing to clone", 1 for "something to clone", or
1718  * the usual negative error code.
1719  */
1720 int vfs_clone_file_prep_inodes(struct inode *inode_in, loff_t pos_in,
1721                                struct inode *inode_out, loff_t pos_out,
1722                                u64 *len, bool is_dedupe)
1723 {
1724         loff_t bs = inode_out->i_sb->s_blocksize;
1725         loff_t blen;
1726         loff_t isize;
1727         bool same_inode = (inode_in == inode_out);
1728         int ret;
1729 
1730         /* Don't touch certain kinds of inodes */
1731         if (IS_IMMUTABLE(inode_out))
1732                 return -EPERM;
1733 
1734         if (IS_SWAPFILE(inode_in) || IS_SWAPFILE(inode_out))
1735                 return -ETXTBSY;
1736 
1737         /* Don't reflink dirs, pipes, sockets... */
1738         if (S_ISDIR(inode_in->i_mode) || S_ISDIR(inode_out->i_mode))
1739                 return -EISDIR;
1740         if (!S_ISREG(inode_in->i_mode) || !S_ISREG(inode_out->i_mode))
1741                 return -EINVAL;
1742 
1743         /* Are we going all the way to the end? */
1744         isize = i_size_read(inode_in);
1745         if (isize == 0)
1746                 return 0;
1747 
1748         /* Zero length dedupe exits immediately; reflink goes to EOF. */
1749         if (*len == 0) {
1750                 if (is_dedupe || pos_in == isize)
1751                         return 0;
1752                 if (pos_in > isize)
1753                         return -EINVAL;
1754                 *len = isize - pos_in;
1755         }
1756 
1757         /* Ensure offsets don't wrap and the input is inside i_size */
1758         if (pos_in + *len < pos_in || pos_out + *len < pos_out ||
1759             pos_in + *len > isize)
1760                 return -EINVAL;
1761 
1762         /* Don't allow dedupe past EOF in the dest file */
1763         if (is_dedupe) {
1764                 loff_t  disize;
1765 
1766                 disize = i_size_read(inode_out);
1767                 if (pos_out >= disize || pos_out + *len > disize)
1768                         return -EINVAL;
1769         }
1770 
1771         /* If we're linking to EOF, continue to the block boundary. */
1772         if (pos_in + *len == isize)
1773                 blen = ALIGN(isize, bs) - pos_in;
1774         else
1775                 blen = *len;
1776 
1777         /* Only reflink if we're aligned to block boundaries */
1778         if (!IS_ALIGNED(pos_in, bs) || !IS_ALIGNED(pos_in + blen, bs) ||
1779             !IS_ALIGNED(pos_out, bs) || !IS_ALIGNED(pos_out + blen, bs))
1780                 return -EINVAL;
1781 
1782         /* Don't allow overlapped reflink within the same file */
1783         if (same_inode) {
1784                 if (pos_out + blen > pos_in && pos_out < pos_in + blen)
1785                         return -EINVAL;
1786         }
1787 
1788         /* Wait for the completion of any pending IOs on both files */
1789         inode_dio_wait(inode_in);
1790         if (!same_inode)
1791                 inode_dio_wait(inode_out);
1792 
1793         ret = filemap_write_and_wait_range(inode_in->i_mapping,
1794                         pos_in, pos_in + *len - 1);
1795         if (ret)
1796                 return ret;
1797 
1798         ret = filemap_write_and_wait_range(inode_out->i_mapping,
1799                         pos_out, pos_out + *len - 1);
1800         if (ret)
1801                 return ret;
1802 
1803         /*
1804          * Check that the extents are the same.
1805          */
1806         if (is_dedupe) {
1807                 bool            is_same = false;
1808 
1809                 ret = vfs_dedupe_file_range_compare(inode_in, pos_in,
1810                                 inode_out, pos_out, *len, &is_same);
1811                 if (ret)
1812                         return ret;
1813                 if (!is_same)
1814                         return -EBADE;
1815         }
1816 
1817         return 1;
1818 }
1819 EXPORT_SYMBOL(vfs_clone_file_prep_inodes);
1820 
1821 int vfs_clone_file_range(struct file *file_in, loff_t pos_in,
1822                 struct file *file_out, loff_t pos_out, u64 len)
1823 {
1824         struct inode *inode_in = file_inode(file_in);
1825         struct inode *inode_out = file_inode(file_out);
1826         int ret;
1827 
1828         if (S_ISDIR(inode_in->i_mode) || S_ISDIR(inode_out->i_mode))
1829                 return -EISDIR;
1830         if (!S_ISREG(inode_in->i_mode) || !S_ISREG(inode_out->i_mode))
1831                 return -EINVAL;
1832 
1833         /*
1834          * FICLONE/FICLONERANGE ioctls enforce that src and dest files are on
1835          * the same mount. Practically, they only need to be on the same file
1836          * system.
1837          */
1838         if (inode_in->i_sb != inode_out->i_sb)
1839                 return -EXDEV;
1840 
1841         if (!(file_in->f_mode & FMODE_READ) ||
1842             !(file_out->f_mode & FMODE_WRITE) ||
1843             (file_out->f_flags & O_APPEND))
1844                 return -EBADF;
1845 
1846         if (!file_in->f_op->clone_file_range)
1847                 return -EOPNOTSUPP;
1848 
1849         ret = clone_verify_area(file_in, pos_in, len, false);
1850         if (ret)
1851                 return ret;
1852 
1853         ret = clone_verify_area(file_out, pos_out, len, true);
1854         if (ret)
1855                 return ret;
1856 
1857         if (pos_in + len > i_size_read(inode_in))
1858                 return -EINVAL;
1859 
1860         ret = file_in->f_op->clone_file_range(file_in, pos_in,
1861                         file_out, pos_out, len);
1862         if (!ret) {
1863                 fsnotify_access(file_in);
1864                 fsnotify_modify(file_out);
1865         }
1866 
1867         return ret;
1868 }
1869 EXPORT_SYMBOL(vfs_clone_file_range);
1870 
1871 /*
1872  * Read a page's worth of file data into the page cache.  Return the page
1873  * locked.
1874  */
1875 static struct page *vfs_dedupe_get_page(struct inode *inode, loff_t offset)
1876 {
1877         struct address_space *mapping;
1878         struct page *page;
1879         pgoff_t n;
1880 
1881         n = offset >> PAGE_SHIFT;
1882         mapping = inode->i_mapping;
1883         page = read_mapping_page(mapping, n, NULL);
1884         if (IS_ERR(page))
1885                 return page;
1886         if (!PageUptodate(page)) {
1887                 put_page(page);
1888                 return ERR_PTR(-EIO);
1889         }
1890         lock_page(page);
1891         return page;
1892 }
1893 
1894 /*
1895  * Compare extents of two files to see if they are the same.
1896  * Caller must have locked both inodes to prevent write races.
1897  */
1898 int vfs_dedupe_file_range_compare(struct inode *src, loff_t srcoff,
1899                                   struct inode *dest, loff_t destoff,
1900                                   loff_t len, bool *is_same)
1901 {
1902         loff_t src_poff;
1903         loff_t dest_poff;
1904         void *src_addr;
1905         void *dest_addr;
1906         struct page *src_page;
1907         struct page *dest_page;
1908         loff_t cmp_len;
1909         bool same;
1910         int error;
1911 
1912         error = -EINVAL;
1913         same = true;
1914         while (len) {
1915                 src_poff = srcoff & (PAGE_SIZE - 1);
1916                 dest_poff = destoff & (PAGE_SIZE - 1);
1917                 cmp_len = min(PAGE_SIZE - src_poff,
1918                               PAGE_SIZE - dest_poff);
1919                 cmp_len = min(cmp_len, len);
1920                 if (cmp_len <= 0)
1921                         goto out_error;
1922 
1923                 src_page = vfs_dedupe_get_page(src, srcoff);
1924                 if (IS_ERR(src_page)) {
1925                         error = PTR_ERR(src_page);
1926                         goto out_error;
1927                 }
1928                 dest_page = vfs_dedupe_get_page(dest, destoff);
1929                 if (IS_ERR(dest_page)) {
1930                         error = PTR_ERR(dest_page);
1931                         unlock_page(src_page);
1932                         put_page(src_page);
1933                         goto out_error;
1934                 }
1935                 src_addr = kmap_atomic(src_page);
1936                 dest_addr = kmap_atomic(dest_page);
1937 
1938                 flush_dcache_page(src_page);
1939                 flush_dcache_page(dest_page);
1940 
1941                 if (memcmp(src_addr + src_poff, dest_addr + dest_poff, cmp_len))
1942                         same = false;
1943 
1944                 kunmap_atomic(dest_addr);
1945                 kunmap_atomic(src_addr);
1946                 unlock_page(dest_page);
1947                 unlock_page(src_page);
1948                 put_page(dest_page);
1949                 put_page(src_page);
1950 
1951                 if (!same)
1952                         break;
1953 
1954                 srcoff += cmp_len;
1955                 destoff += cmp_len;
1956                 len -= cmp_len;
1957         }
1958 
1959         *is_same = same;
1960         return 0;
1961 
1962 out_error:
1963         return error;
1964 }
1965 EXPORT_SYMBOL(vfs_dedupe_file_range_compare);
1966 
1967 int vfs_dedupe_file_range(struct file *file, struct file_dedupe_range *same)
1968 {
1969         struct file_dedupe_range_info *info;
1970         struct inode *src = file_inode(file);
1971         u64 off;
1972         u64 len;
1973         int i;
1974         int ret;
1975         bool is_admin = capable(CAP_SYS_ADMIN);
1976         u16 count = same->dest_count;
1977         struct file *dst_file;
1978         loff_t dst_off;
1979         ssize_t deduped;
1980 
1981         if (!(file->f_mode & FMODE_READ))
1982                 return -EINVAL;
1983 
1984         if (same->reserved1 || same->reserved2)
1985                 return -EINVAL;
1986 
1987         off = same->src_offset;
1988         len = same->src_length;
1989 
1990         ret = -EISDIR;
1991         if (S_ISDIR(src->i_mode))
1992                 goto out;
1993 
1994         ret = -EINVAL;
1995         if (!S_ISREG(src->i_mode))
1996                 goto out;
1997 
1998         ret = clone_verify_area(file, off, len, false);
1999         if (ret < 0)
2000                 goto out;
2001         ret = 0;
2002 
2003         if (off + len > i_size_read(src))
2004                 return -EINVAL;
2005 
2006         /* pre-format output fields to sane values */
2007         for (i = 0; i < count; i++) {
2008                 same->info[i].bytes_deduped = 0ULL;
2009                 same->info[i].status = FILE_DEDUPE_RANGE_SAME;
2010         }
2011 
2012         for (i = 0, info = same->info; i < count; i++, info++) {
2013                 struct inode *dst;
2014                 struct fd dst_fd = fdget(info->dest_fd);
2015 
2016                 dst_file = dst_fd.file;
2017                 if (!dst_file) {
2018                         info->status = -EBADF;
2019                         goto next_loop;
2020                 }
2021                 dst = file_inode(dst_file);
2022 
2023                 ret = mnt_want_write_file(dst_file);
2024                 if (ret) {
2025                         info->status = ret;
2026                         goto next_loop;
2027                 }
2028 
2029                 dst_off = info->dest_offset;
2030                 ret = clone_verify_area(dst_file, dst_off, len, true);
2031                 if (ret < 0) {
2032                         info->status = ret;
2033                         goto next_file;
2034                 }
2035                 ret = 0;
2036 
2037                 if (info->reserved) {
2038                         info->status = -EINVAL;
2039                 } else if (!(is_admin || (dst_file->f_mode & FMODE_WRITE))) {
2040                         info->status = -EINVAL;
2041                 } else if (file->f_path.mnt != dst_file->f_path.mnt) {
2042                         info->status = -EXDEV;
2043                 } else if (S_ISDIR(dst->i_mode)) {
2044                         info->status = -EISDIR;
2045                 } else if (dst_file->f_op->dedupe_file_range == NULL) {
2046                         info->status = -EINVAL;
2047                 } else {
2048                         deduped = dst_file->f_op->dedupe_file_range(file, off,
2049                                                         len, dst_file,
2050                                                         info->dest_offset);
2051                         if (deduped == -EBADE)
2052                                 info->status = FILE_DEDUPE_RANGE_DIFFERS;
2053                         else if (deduped < 0)
2054                                 info->status = deduped;
2055                         else
2056                                 info->bytes_deduped += deduped;
2057                 }
2058 
2059 next_file:
2060                 mnt_drop_write_file(dst_file);
2061 next_loop:
2062                 fdput(dst_fd);
2063 
2064                 if (fatal_signal_pending(current))
2065                         goto out;
2066         }
2067 
2068 out:
2069         return ret;
2070 }
2071 EXPORT_SYMBOL(vfs_dedupe_file_range);
2072 

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