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x86/debug: Drop several unnecessary CFI annotations
[deliverable/linux.git] / fs / read_write.c
1 /*
2 * linux/fs/read_write.c
3 *
4 * Copyright (C) 1991, 1992 Linus Torvalds
5 */
6
7 #include <linux/slab.h>
8 #include <linux/stat.h>
9 #include <linux/fcntl.h>
10 #include <linux/file.h>
11 #include <linux/uio.h>
12 #include <linux/aio.h>
13 #include <linux/fsnotify.h>
14 #include <linux/security.h>
15 #include <linux/export.h>
16 #include <linux/syscalls.h>
17 #include <linux/pagemap.h>
18 #include <linux/splice.h>
19 #include <linux/compat.h>
20 #include "internal.h"
21
22 #include <asm/uaccess.h>
23 #include <asm/unistd.h>
24
25 typedef ssize_t (*io_fn_t)(struct file *, char __user *, size_t, loff_t *);
26 typedef ssize_t (*iov_fn_t)(struct kiocb *, const struct iovec *,
27 unsigned long, loff_t);
28 typedef ssize_t (*iter_fn_t)(struct kiocb *, struct iov_iter *);
29
30 const struct file_operations generic_ro_fops = {
31 .llseek = generic_file_llseek,
32 .read = new_sync_read,
33 .read_iter = generic_file_read_iter,
34 .mmap = generic_file_readonly_mmap,
35 .splice_read = generic_file_splice_read,
36 };
37
38 EXPORT_SYMBOL(generic_ro_fops);
39
40 static inline int unsigned_offsets(struct file *file)
41 {
42 return file->f_mode & FMODE_UNSIGNED_OFFSET;
43 }
44
45 /**
46 * vfs_setpos - update the file offset for lseek
47 * @file: file structure in question
48 * @offset: file offset to seek to
49 * @maxsize: maximum file size
50 *
51 * This is a low-level filesystem helper for updating the file offset to
52 * the value specified by @offset if the given offset is valid and it is
53 * not equal to the current file offset.
54 *
55 * Return the specified offset on success and -EINVAL on invalid offset.
56 */
57 loff_t vfs_setpos(struct file *file, loff_t offset, loff_t maxsize)
58 {
59 if (offset < 0 && !unsigned_offsets(file))
60 return -EINVAL;
61 if (offset > maxsize)
62 return -EINVAL;
63
64 if (offset != file->f_pos) {
65 file->f_pos = offset;
66 file->f_version = 0;
67 }
68 return offset;
69 }
70 EXPORT_SYMBOL(vfs_setpos);
71
72 /**
73 * generic_file_llseek_size - generic llseek implementation for regular files
74 * @file: file structure to seek on
75 * @offset: file offset to seek to
76 * @whence: type of seek
77 * @size: max size of this file in file system
78 * @eof: offset used for SEEK_END position
79 *
80 * This is a variant of generic_file_llseek that allows passing in a custom
81 * maximum file size and a custom EOF position, for e.g. hashed directories
82 *
83 * Synchronization:
84 * SEEK_SET and SEEK_END are unsynchronized (but atomic on 64bit platforms)
85 * SEEK_CUR is synchronized against other SEEK_CURs, but not read/writes.
86 * read/writes behave like SEEK_SET against seeks.
87 */
88 loff_t
89 generic_file_llseek_size(struct file *file, loff_t offset, int whence,
90 loff_t maxsize, loff_t eof)
91 {
92 switch (whence) {
93 case SEEK_END:
94 offset += eof;
95 break;
96 case SEEK_CUR:
97 /*
98 * Here we special-case the lseek(fd, 0, SEEK_CUR)
99 * position-querying operation. Avoid rewriting the "same"
100 * f_pos value back to the file because a concurrent read(),
101 * write() or lseek() might have altered it
102 */
103 if (offset == 0)
104 return file->f_pos;
105 /*
106 * f_lock protects against read/modify/write race with other
107 * SEEK_CURs. Note that parallel writes and reads behave
108 * like SEEK_SET.
109 */
110 spin_lock(&file->f_lock);
111 offset = vfs_setpos(file, file->f_pos + offset, maxsize);
112 spin_unlock(&file->f_lock);
113 return offset;
114 case SEEK_DATA:
115 /*
116 * In the generic case the entire file is data, so as long as
117 * offset isn't at the end of the file then the offset is data.
118 */
119 if (offset >= eof)
120 return -ENXIO;
121 break;
122 case SEEK_HOLE:
123 /*
124 * There is a virtual hole at the end of the file, so as long as
125 * offset isn't i_size or larger, return i_size.
126 */
127 if (offset >= eof)
128 return -ENXIO;
129 offset = eof;
130 break;
131 }
132
133 return vfs_setpos(file, offset, maxsize);
134 }
135 EXPORT_SYMBOL(generic_file_llseek_size);
136
137 /**
138 * generic_file_llseek - generic llseek implementation for regular files
139 * @file: file structure to seek on
140 * @offset: file offset to seek to
141 * @whence: type of seek
142 *
143 * This is a generic implemenation of ->llseek useable for all normal local
144 * filesystems. It just updates the file offset to the value specified by
145 * @offset and @whence.
146 */
147 loff_t generic_file_llseek(struct file *file, loff_t offset, int whence)
148 {
149 struct inode *inode = file->f_mapping->host;
150
151 return generic_file_llseek_size(file, offset, whence,
152 inode->i_sb->s_maxbytes,
153 i_size_read(inode));
154 }
155 EXPORT_SYMBOL(generic_file_llseek);
156
157 /**
158 * fixed_size_llseek - llseek implementation for fixed-sized devices
159 * @file: file structure to seek on
160 * @offset: file offset to seek to
161 * @whence: type of seek
162 * @size: size of the file
163 *
164 */
165 loff_t fixed_size_llseek(struct file *file, loff_t offset, int whence, loff_t size)
166 {
167 switch (whence) {
168 case SEEK_SET: case SEEK_CUR: case SEEK_END:
169 return generic_file_llseek_size(file, offset, whence,
170 size, size);
171 default:
172 return -EINVAL;
173 }
174 }
175 EXPORT_SYMBOL(fixed_size_llseek);
176
177 /**
178 * noop_llseek - No Operation Performed llseek implementation
179 * @file: file structure to seek on
180 * @offset: file offset to seek to
181 * @whence: type of seek
182 *
183 * This is an implementation of ->llseek useable for the rare special case when
184 * userspace expects the seek to succeed but the (device) file is actually not
185 * able to perform the seek. In this case you use noop_llseek() instead of
186 * falling back to the default implementation of ->llseek.
187 */
188 loff_t noop_llseek(struct file *file, loff_t offset, int whence)
189 {
190 return file->f_pos;
191 }
192 EXPORT_SYMBOL(noop_llseek);
193
194 loff_t no_llseek(struct file *file, loff_t offset, int whence)
195 {
196 return -ESPIPE;
197 }
198 EXPORT_SYMBOL(no_llseek);
199
200 loff_t default_llseek(struct file *file, loff_t offset, int whence)
201 {
202 struct inode *inode = file_inode(file);
203 loff_t retval;
204
205 mutex_lock(&inode->i_mutex);
206 switch (whence) {
207 case SEEK_END:
208 offset += i_size_read(inode);
209 break;
210 case SEEK_CUR:
211 if (offset == 0) {
212 retval = file->f_pos;
213 goto out;
214 }
215 offset += file->f_pos;
216 break;
217 case SEEK_DATA:
218 /*
219 * In the generic case the entire file is data, so as
220 * long as offset isn't at the end of the file then the
221 * offset is data.
222 */
223 if (offset >= inode->i_size) {
224 retval = -ENXIO;
225 goto out;
226 }
227 break;
228 case SEEK_HOLE:
229 /*
230 * There is a virtual hole at the end of the file, so
231 * as long as offset isn't i_size or larger, return
232 * i_size.
233 */
234 if (offset >= inode->i_size) {
235 retval = -ENXIO;
236 goto out;
237 }
238 offset = inode->i_size;
239 break;
240 }
241 retval = -EINVAL;
242 if (offset >= 0 || unsigned_offsets(file)) {
243 if (offset != file->f_pos) {
244 file->f_pos = offset;
245 file->f_version = 0;
246 }
247 retval = offset;
248 }
249 out:
250 mutex_unlock(&inode->i_mutex);
251 return retval;
252 }
253 EXPORT_SYMBOL(default_llseek);
254
255 loff_t vfs_llseek(struct file *file, loff_t offset, int whence)
256 {
257 loff_t (*fn)(struct file *, loff_t, int);
258
259 fn = no_llseek;
260 if (file->f_mode & FMODE_LSEEK) {
261 if (file->f_op->llseek)
262 fn = file->f_op->llseek;
263 }
264 return fn(file, offset, whence);
265 }
266 EXPORT_SYMBOL(vfs_llseek);
267
268 static inline struct fd fdget_pos(int fd)
269 {
270 return __to_fd(__fdget_pos(fd));
271 }
272
273 static inline void fdput_pos(struct fd f)
274 {
275 if (f.flags & FDPUT_POS_UNLOCK)
276 mutex_unlock(&f.file->f_pos_lock);
277 fdput(f);
278 }
279
280 SYSCALL_DEFINE3(lseek, unsigned int, fd, off_t, offset, unsigned int, whence)
281 {
282 off_t retval;
283 struct fd f = fdget_pos(fd);
284 if (!f.file)
285 return -EBADF;
286
287 retval = -EINVAL;
288 if (whence <= SEEK_MAX) {
289 loff_t res = vfs_llseek(f.file, offset, whence);
290 retval = res;
291 if (res != (loff_t)retval)
292 retval = -EOVERFLOW; /* LFS: should only happen on 32 bit platforms */
293 }
294 fdput_pos(f);
295 return retval;
296 }
297
298 #ifdef CONFIG_COMPAT
299 COMPAT_SYSCALL_DEFINE3(lseek, unsigned int, fd, compat_off_t, offset, unsigned int, whence)
300 {
301 return sys_lseek(fd, offset, whence);
302 }
303 #endif
304
305 #ifdef __ARCH_WANT_SYS_LLSEEK
306 SYSCALL_DEFINE5(llseek, unsigned int, fd, unsigned long, offset_high,
307 unsigned long, offset_low, loff_t __user *, result,
308 unsigned int, whence)
309 {
310 int retval;
311 struct fd f = fdget_pos(fd);
312 loff_t offset;
313
314 if (!f.file)
315 return -EBADF;
316
317 retval = -EINVAL;
318 if (whence > SEEK_MAX)
319 goto out_putf;
320
321 offset = vfs_llseek(f.file, ((loff_t) offset_high << 32) | offset_low,
322 whence);
323
324 retval = (int)offset;
325 if (offset >= 0) {
326 retval = -EFAULT;
327 if (!copy_to_user(result, &offset, sizeof(offset)))
328 retval = 0;
329 }
330 out_putf:
331 fdput_pos(f);
332 return retval;
333 }
334 #endif
335
336 /*
337 * rw_verify_area doesn't like huge counts. We limit
338 * them to something that fits in "int" so that others
339 * won't have to do range checks all the time.
340 */
341 int rw_verify_area(int read_write, struct file *file, const loff_t *ppos, size_t count)
342 {
343 struct inode *inode;
344 loff_t pos;
345 int retval = -EINVAL;
346
347 inode = file_inode(file);
348 if (unlikely((ssize_t) count < 0))
349 return retval;
350 pos = *ppos;
351 if (unlikely(pos < 0)) {
352 if (!unsigned_offsets(file))
353 return retval;
354 if (count >= -pos) /* both values are in 0..LLONG_MAX */
355 return -EOVERFLOW;
356 } else if (unlikely((loff_t) (pos + count) < 0)) {
357 if (!unsigned_offsets(file))
358 return retval;
359 }
360
361 if (unlikely(inode->i_flock && mandatory_lock(inode))) {
362 retval = locks_mandatory_area(
363 read_write == READ ? FLOCK_VERIFY_READ : FLOCK_VERIFY_WRITE,
364 inode, file, pos, count);
365 if (retval < 0)
366 return retval;
367 }
368 retval = security_file_permission(file,
369 read_write == READ ? MAY_READ : MAY_WRITE);
370 if (retval)
371 return retval;
372 return count > MAX_RW_COUNT ? MAX_RW_COUNT : count;
373 }
374
375 ssize_t do_sync_read(struct file *filp, char __user *buf, size_t len, loff_t *ppos)
376 {
377 struct iovec iov = { .iov_base = buf, .iov_len = len };
378 struct kiocb kiocb;
379 ssize_t ret;
380
381 init_sync_kiocb(&kiocb, filp);
382 kiocb.ki_pos = *ppos;
383 kiocb.ki_nbytes = len;
384
385 ret = filp->f_op->aio_read(&kiocb, &iov, 1, kiocb.ki_pos);
386 if (-EIOCBQUEUED == ret)
387 ret = wait_on_sync_kiocb(&kiocb);
388 *ppos = kiocb.ki_pos;
389 return ret;
390 }
391
392 EXPORT_SYMBOL(do_sync_read);
393
394 ssize_t new_sync_read(struct file *filp, char __user *buf, size_t len, loff_t *ppos)
395 {
396 struct iovec iov = { .iov_base = buf, .iov_len = len };
397 struct kiocb kiocb;
398 struct iov_iter iter;
399 ssize_t ret;
400
401 init_sync_kiocb(&kiocb, filp);
402 kiocb.ki_pos = *ppos;
403 kiocb.ki_nbytes = len;
404 iov_iter_init(&iter, READ, &iov, 1, len);
405
406 ret = filp->f_op->read_iter(&kiocb, &iter);
407 if (-EIOCBQUEUED == ret)
408 ret = wait_on_sync_kiocb(&kiocb);
409 *ppos = kiocb.ki_pos;
410 return ret;
411 }
412
413 EXPORT_SYMBOL(new_sync_read);
414
415 ssize_t vfs_read(struct file *file, char __user *buf, size_t count, loff_t *pos)
416 {
417 ssize_t ret;
418
419 if (!(file->f_mode & FMODE_READ))
420 return -EBADF;
421 if (!(file->f_mode & FMODE_CAN_READ))
422 return -EINVAL;
423 if (unlikely(!access_ok(VERIFY_WRITE, buf, count)))
424 return -EFAULT;
425
426 ret = rw_verify_area(READ, file, pos, count);
427 if (ret >= 0) {
428 count = ret;
429 if (file->f_op->read)
430 ret = file->f_op->read(file, buf, count, pos);
431 else if (file->f_op->aio_read)
432 ret = do_sync_read(file, buf, count, pos);
433 else
434 ret = new_sync_read(file, buf, count, pos);
435 if (ret > 0) {
436 fsnotify_access(file);
437 add_rchar(current, ret);
438 }
439 inc_syscr(current);
440 }
441
442 return ret;
443 }
444
445 EXPORT_SYMBOL(vfs_read);
446
447 ssize_t do_sync_write(struct file *filp, const char __user *buf, size_t len, loff_t *ppos)
448 {
449 struct iovec iov = { .iov_base = (void __user *)buf, .iov_len = len };
450 struct kiocb kiocb;
451 ssize_t ret;
452
453 init_sync_kiocb(&kiocb, filp);
454 kiocb.ki_pos = *ppos;
455 kiocb.ki_nbytes = len;
456
457 ret = filp->f_op->aio_write(&kiocb, &iov, 1, kiocb.ki_pos);
458 if (-EIOCBQUEUED == ret)
459 ret = wait_on_sync_kiocb(&kiocb);
460 *ppos = kiocb.ki_pos;
461 return ret;
462 }
463
464 EXPORT_SYMBOL(do_sync_write);
465
466 ssize_t new_sync_write(struct file *filp, const char __user *buf, size_t len, loff_t *ppos)
467 {
468 struct iovec iov = { .iov_base = (void __user *)buf, .iov_len = len };
469 struct kiocb kiocb;
470 struct iov_iter iter;
471 ssize_t ret;
472
473 init_sync_kiocb(&kiocb, filp);
474 kiocb.ki_pos = *ppos;
475 kiocb.ki_nbytes = len;
476 iov_iter_init(&iter, WRITE, &iov, 1, len);
477
478 ret = filp->f_op->write_iter(&kiocb, &iter);
479 if (-EIOCBQUEUED == ret)
480 ret = wait_on_sync_kiocb(&kiocb);
481 *ppos = kiocb.ki_pos;
482 return ret;
483 }
484
485 EXPORT_SYMBOL(new_sync_write);
486
487 ssize_t __kernel_write(struct file *file, const char *buf, size_t count, loff_t *pos)
488 {
489 mm_segment_t old_fs;
490 const char __user *p;
491 ssize_t ret;
492
493 if (!(file->f_mode & FMODE_CAN_WRITE))
494 return -EINVAL;
495
496 old_fs = get_fs();
497 set_fs(get_ds());
498 p = (__force const char __user *)buf;
499 if (count > MAX_RW_COUNT)
500 count = MAX_RW_COUNT;
501 if (file->f_op->write)
502 ret = file->f_op->write(file, p, count, pos);
503 else if (file->f_op->aio_write)
504 ret = do_sync_write(file, p, count, pos);
505 else
506 ret = new_sync_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
516 ssize_t vfs_write(struct file *file, const char __user *buf, size_t count, loff_t *pos)
517 {
518 ssize_t ret;
519
520 if (!(file->f_mode & FMODE_WRITE))
521 return -EBADF;
522 if (!(file->f_mode & FMODE_CAN_WRITE))
523 return -EINVAL;
524 if (unlikely(!access_ok(VERIFY_READ, buf, count)))
525 return -EFAULT;
526
527 ret = rw_verify_area(WRITE, file, pos, count);
528 if (ret >= 0) {
529 count = ret;
530 file_start_write(file);
531 if (file->f_op->write)
532 ret = file->f_op->write(file, buf, count, pos);
533 else if (file->f_op->aio_write)
534 ret = do_sync_write(file, buf, count, pos);
535 else
536 ret = new_sync_write(file, buf, count, pos);
537 if (ret > 0) {
538 fsnotify_modify(file);
539 add_wchar(current, ret);
540 }
541 inc_syscw(current);
542 file_end_write(file);
543 }
544
545 return ret;
546 }
547
548 EXPORT_SYMBOL(vfs_write);
549
550 static inline loff_t file_pos_read(struct file *file)
551 {
552 return file->f_pos;
553 }
554
555 static inline void file_pos_write(struct file *file, loff_t pos)
556 {
557 file->f_pos = pos;
558 }
559
560 SYSCALL_DEFINE3(read, unsigned int, fd, char __user *, buf, size_t, count)
561 {
562 struct fd f = fdget_pos(fd);
563 ssize_t ret = -EBADF;
564
565 if (f.file) {
566 loff_t pos = file_pos_read(f.file);
567 ret = vfs_read(f.file, buf, count, &pos);
568 if (ret >= 0)
569 file_pos_write(f.file, pos);
570 fdput_pos(f);
571 }
572 return ret;
573 }
574
575 SYSCALL_DEFINE3(write, unsigned int, fd, const char __user *, buf,
576 size_t, count)
577 {
578 struct fd f = fdget_pos(fd);
579 ssize_t ret = -EBADF;
580
581 if (f.file) {
582 loff_t pos = file_pos_read(f.file);
583 ret = vfs_write(f.file, buf, count, &pos);
584 if (ret >= 0)
585 file_pos_write(f.file, pos);
586 fdput_pos(f);
587 }
588
589 return ret;
590 }
591
592 SYSCALL_DEFINE4(pread64, unsigned int, fd, char __user *, buf,
593 size_t, count, loff_t, pos)
594 {
595 struct fd f;
596 ssize_t ret = -EBADF;
597
598 if (pos < 0)
599 return -EINVAL;
600
601 f = fdget(fd);
602 if (f.file) {
603 ret = -ESPIPE;
604 if (f.file->f_mode & FMODE_PREAD)
605 ret = vfs_read(f.file, buf, count, &pos);
606 fdput(f);
607 }
608
609 return ret;
610 }
611
612 SYSCALL_DEFINE4(pwrite64, unsigned int, fd, const char __user *, buf,
613 size_t, count, loff_t, pos)
614 {
615 struct fd f;
616 ssize_t ret = -EBADF;
617
618 if (pos < 0)
619 return -EINVAL;
620
621 f = fdget(fd);
622 if (f.file) {
623 ret = -ESPIPE;
624 if (f.file->f_mode & FMODE_PWRITE)
625 ret = vfs_write(f.file, buf, count, &pos);
626 fdput(f);
627 }
628
629 return ret;
630 }
631
632 /*
633 * Reduce an iovec's length in-place. Return the resulting number of segments
634 */
635 unsigned long iov_shorten(struct iovec *iov, unsigned long nr_segs, size_t to)
636 {
637 unsigned long seg = 0;
638 size_t len = 0;
639
640 while (seg < nr_segs) {
641 seg++;
642 if (len + iov->iov_len >= to) {
643 iov->iov_len = to - len;
644 break;
645 }
646 len += iov->iov_len;
647 iov++;
648 }
649 return seg;
650 }
651 EXPORT_SYMBOL(iov_shorten);
652
653 static ssize_t do_iter_readv_writev(struct file *filp, int rw, const struct iovec *iov,
654 unsigned long nr_segs, size_t len, loff_t *ppos, iter_fn_t fn)
655 {
656 struct kiocb kiocb;
657 struct iov_iter iter;
658 ssize_t ret;
659
660 init_sync_kiocb(&kiocb, filp);
661 kiocb.ki_pos = *ppos;
662 kiocb.ki_nbytes = len;
663
664 iov_iter_init(&iter, rw, iov, nr_segs, len);
665 ret = fn(&kiocb, &iter);
666 if (ret == -EIOCBQUEUED)
667 ret = wait_on_sync_kiocb(&kiocb);
668 *ppos = kiocb.ki_pos;
669 return ret;
670 }
671
672 static ssize_t do_sync_readv_writev(struct file *filp, const struct iovec *iov,
673 unsigned long nr_segs, size_t len, loff_t *ppos, iov_fn_t fn)
674 {
675 struct kiocb kiocb;
676 ssize_t ret;
677
678 init_sync_kiocb(&kiocb, filp);
679 kiocb.ki_pos = *ppos;
680 kiocb.ki_nbytes = len;
681
682 ret = fn(&kiocb, iov, nr_segs, kiocb.ki_pos);
683 if (ret == -EIOCBQUEUED)
684 ret = wait_on_sync_kiocb(&kiocb);
685 *ppos = kiocb.ki_pos;
686 return ret;
687 }
688
689 /* Do it by hand, with file-ops */
690 static ssize_t do_loop_readv_writev(struct file *filp, struct iovec *iov,
691 unsigned long nr_segs, loff_t *ppos, io_fn_t fn)
692 {
693 struct iovec *vector = iov;
694 ssize_t ret = 0;
695
696 while (nr_segs > 0) {
697 void __user *base;
698 size_t len;
699 ssize_t nr;
700
701 base = vector->iov_base;
702 len = vector->iov_len;
703 vector++;
704 nr_segs--;
705
706 nr = fn(filp, base, len, ppos);
707
708 if (nr < 0) {
709 if (!ret)
710 ret = nr;
711 break;
712 }
713 ret += nr;
714 if (nr != len)
715 break;
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 ssize_t rw_copy_check_uvector(int type, const struct iovec __user * uvector,
725 unsigned long nr_segs, unsigned long fast_segs,
726 struct iovec *fast_pointer,
727 struct iovec **ret_pointer)
728 {
729 unsigned long seg;
730 ssize_t ret;
731 struct iovec *iov = fast_pointer;
732
733 /*
734 * SuS says "The readv() function *may* fail if the iovcnt argument
735 * was less than or equal to 0, or greater than {IOV_MAX}. Linux has
736 * traditionally returned zero for zero segments, so...
737 */
738 if (nr_segs == 0) {
739 ret = 0;
740 goto out;
741 }
742
743 /*
744 * First get the "struct iovec" from user memory and
745 * verify all the pointers
746 */
747 if (nr_segs > UIO_MAXIOV) {
748 ret = -EINVAL;
749 goto out;
750 }
751 if (nr_segs > fast_segs) {
752 iov = kmalloc(nr_segs*sizeof(struct iovec), GFP_KERNEL);
753 if (iov == NULL) {
754 ret = -ENOMEM;
755 goto out;
756 }
757 }
758 if (copy_from_user(iov, uvector, nr_segs*sizeof(*uvector))) {
759 ret = -EFAULT;
760 goto out;
761 }
762
763 /*
764 * According to the Single Unix Specification we should return EINVAL
765 * if an element length is < 0 when cast to ssize_t or if the
766 * total length would overflow the ssize_t return value of the
767 * system call.
768 *
769 * Linux caps all read/write calls to MAX_RW_COUNT, and avoids the
770 * overflow case.
771 */
772 ret = 0;
773 for (seg = 0; seg < nr_segs; seg++) {
774 void __user *buf = iov[seg].iov_base;
775 ssize_t len = (ssize_t)iov[seg].iov_len;
776
777 /* see if we we're about to use an invalid len or if
778 * it's about to overflow ssize_t */
779 if (len < 0) {
780 ret = -EINVAL;
781 goto out;
782 }
783 if (type >= 0
784 && unlikely(!access_ok(vrfy_dir(type), buf, len))) {
785 ret = -EFAULT;
786 goto out;
787 }
788 if (len > MAX_RW_COUNT - ret) {
789 len = MAX_RW_COUNT - ret;
790 iov[seg].iov_len = len;
791 }
792 ret += len;
793 }
794 out:
795 *ret_pointer = iov;
796 return ret;
797 }
798
799 static ssize_t do_readv_writev(int type, struct file *file,
800 const struct iovec __user * uvector,
801 unsigned long nr_segs, loff_t *pos)
802 {
803 size_t tot_len;
804 struct iovec iovstack[UIO_FASTIOV];
805 struct iovec *iov = iovstack;
806 ssize_t ret;
807 io_fn_t fn;
808 iov_fn_t fnv;
809 iter_fn_t iter_fn;
810
811 ret = rw_copy_check_uvector(type, uvector, nr_segs,
812 ARRAY_SIZE(iovstack), iovstack, &iov);
813 if (ret <= 0)
814 goto out;
815
816 tot_len = ret;
817 ret = rw_verify_area(type, file, pos, tot_len);
818 if (ret < 0)
819 goto out;
820
821 fnv = NULL;
822 if (type == READ) {
823 fn = file->f_op->read;
824 fnv = file->f_op->aio_read;
825 iter_fn = file->f_op->read_iter;
826 } else {
827 fn = (io_fn_t)file->f_op->write;
828 fnv = file->f_op->aio_write;
829 iter_fn = file->f_op->write_iter;
830 file_start_write(file);
831 }
832
833 if (iter_fn)
834 ret = do_iter_readv_writev(file, type, iov, nr_segs, tot_len,
835 pos, iter_fn);
836 else if (fnv)
837 ret = do_sync_readv_writev(file, iov, nr_segs, tot_len,
838 pos, fnv);
839 else
840 ret = do_loop_readv_writev(file, iov, nr_segs, pos, fn);
841
842 if (type != READ)
843 file_end_write(file);
844
845 out:
846 if (iov != iovstack)
847 kfree(iov);
848 if ((ret + (type == READ)) > 0) {
849 if (type == READ)
850 fsnotify_access(file);
851 else
852 fsnotify_modify(file);
853 }
854 return ret;
855 }
856
857 ssize_t vfs_readv(struct file *file, const struct iovec __user *vec,
858 unsigned long vlen, loff_t *pos)
859 {
860 if (!(file->f_mode & FMODE_READ))
861 return -EBADF;
862 if (!(file->f_mode & FMODE_CAN_READ))
863 return -EINVAL;
864
865 return do_readv_writev(READ, file, vec, vlen, pos);
866 }
867
868 EXPORT_SYMBOL(vfs_readv);
869
870 ssize_t vfs_writev(struct file *file, const struct iovec __user *vec,
871 unsigned long vlen, loff_t *pos)
872 {
873 if (!(file->f_mode & FMODE_WRITE))
874 return -EBADF;
875 if (!(file->f_mode & FMODE_CAN_WRITE))
876 return -EINVAL;
877
878 return do_readv_writev(WRITE, file, vec, vlen, pos);
879 }
880
881 EXPORT_SYMBOL(vfs_writev);
882
883 SYSCALL_DEFINE3(readv, unsigned long, fd, const struct iovec __user *, vec,
884 unsigned long, vlen)
885 {
886 struct fd f = fdget_pos(fd);
887 ssize_t ret = -EBADF;
888
889 if (f.file) {
890 loff_t pos = file_pos_read(f.file);
891 ret = vfs_readv(f.file, vec, vlen, &pos);
892 if (ret >= 0)
893 file_pos_write(f.file, pos);
894 fdput_pos(f);
895 }
896
897 if (ret > 0)
898 add_rchar(current, ret);
899 inc_syscr(current);
900 return ret;
901 }
902
903 SYSCALL_DEFINE3(writev, unsigned long, fd, const struct iovec __user *, vec,
904 unsigned long, vlen)
905 {
906 struct fd f = fdget_pos(fd);
907 ssize_t ret = -EBADF;
908
909 if (f.file) {
910 loff_t pos = file_pos_read(f.file);
911 ret = vfs_writev(f.file, vec, vlen, &pos);
912 if (ret >= 0)
913 file_pos_write(f.file, pos);
914 fdput_pos(f);
915 }
916
917 if (ret > 0)
918 add_wchar(current, ret);
919 inc_syscw(current);
920 return ret;
921 }
922
923 static inline loff_t pos_from_hilo(unsigned long high, unsigned long low)
924 {
925 #define HALF_LONG_BITS (BITS_PER_LONG / 2)
926 return (((loff_t)high << HALF_LONG_BITS) << HALF_LONG_BITS) | low;
927 }
928
929 SYSCALL_DEFINE5(preadv, unsigned long, fd, const struct iovec __user *, vec,
930 unsigned long, vlen, unsigned long, pos_l, unsigned long, pos_h)
931 {
932 loff_t pos = pos_from_hilo(pos_h, pos_l);
933 struct fd f;
934 ssize_t ret = -EBADF;
935
936 if (pos < 0)
937 return -EINVAL;
938
939 f = fdget(fd);
940 if (f.file) {
941 ret = -ESPIPE;
942 if (f.file->f_mode & FMODE_PREAD)
943 ret = vfs_readv(f.file, vec, vlen, &pos);
944 fdput(f);
945 }
946
947 if (ret > 0)
948 add_rchar(current, ret);
949 inc_syscr(current);
950 return ret;
951 }
952
953 SYSCALL_DEFINE5(pwritev, unsigned long, fd, const struct iovec __user *, vec,
954 unsigned long, vlen, unsigned long, pos_l, unsigned long, pos_h)
955 {
956 loff_t pos = pos_from_hilo(pos_h, pos_l);
957 struct fd f;
958 ssize_t ret = -EBADF;
959
960 if (pos < 0)
961 return -EINVAL;
962
963 f = fdget(fd);
964 if (f.file) {
965 ret = -ESPIPE;
966 if (f.file->f_mode & FMODE_PWRITE)
967 ret = vfs_writev(f.file, vec, vlen, &pos);
968 fdput(f);
969 }
970
971 if (ret > 0)
972 add_wchar(current, ret);
973 inc_syscw(current);
974 return ret;
975 }
976
977 #ifdef CONFIG_COMPAT
978
979 static ssize_t compat_do_readv_writev(int type, struct file *file,
980 const struct compat_iovec __user *uvector,
981 unsigned long nr_segs, loff_t *pos)
982 {
983 compat_ssize_t tot_len;
984 struct iovec iovstack[UIO_FASTIOV];
985 struct iovec *iov = iovstack;
986 ssize_t ret;
987 io_fn_t fn;
988 iov_fn_t fnv;
989 iter_fn_t iter_fn;
990
991 ret = compat_rw_copy_check_uvector(type, uvector, nr_segs,
992 UIO_FASTIOV, iovstack, &iov);
993 if (ret <= 0)
994 goto out;
995
996 tot_len = ret;
997 ret = rw_verify_area(type, file, pos, tot_len);
998 if (ret < 0)
999 goto out;
1000
1001 fnv = NULL;
1002 if (type == READ) {
1003 fn = file->f_op->read;
1004 fnv = file->f_op->aio_read;
1005 iter_fn = file->f_op->read_iter;
1006 } else {
1007 fn = (io_fn_t)file->f_op->write;
1008 fnv = file->f_op->aio_write;
1009 iter_fn = file->f_op->write_iter;
1010 file_start_write(file);
1011 }
1012
1013 if (iter_fn)
1014 ret = do_iter_readv_writev(file, type, iov, nr_segs, tot_len,
1015 pos, iter_fn);
1016 else if (fnv)
1017 ret = do_sync_readv_writev(file, iov, nr_segs, tot_len,
1018 pos, fnv);
1019 else
1020 ret = do_loop_readv_writev(file, iov, nr_segs, pos, fn);
1021
1022 if (type != READ)
1023 file_end_write(file);
1024
1025 out:
1026 if (iov != iovstack)
1027 kfree(iov);
1028 if ((ret + (type == READ)) > 0) {
1029 if (type == READ)
1030 fsnotify_access(file);
1031 else
1032 fsnotify_modify(file);
1033 }
1034 return ret;
1035 }
1036
1037 static size_t compat_readv(struct file *file,
1038 const struct compat_iovec __user *vec,
1039 unsigned long vlen, loff_t *pos)
1040 {
1041 ssize_t ret = -EBADF;
1042
1043 if (!(file->f_mode & FMODE_READ))
1044 goto out;
1045
1046 ret = -EINVAL;
1047 if (!(file->f_mode & FMODE_CAN_READ))
1048 goto out;
1049
1050 ret = compat_do_readv_writev(READ, file, vec, vlen, pos);
1051
1052 out:
1053 if (ret > 0)
1054 add_rchar(current, ret);
1055 inc_syscr(current);
1056 return ret;
1057 }
1058
1059 COMPAT_SYSCALL_DEFINE3(readv, compat_ulong_t, fd,
1060 const struct compat_iovec __user *,vec,
1061 compat_ulong_t, vlen)
1062 {
1063 struct fd f = fdget_pos(fd);
1064 ssize_t ret;
1065 loff_t pos;
1066
1067 if (!f.file)
1068 return -EBADF;
1069 pos = f.file->f_pos;
1070 ret = compat_readv(f.file, vec, vlen, &pos);
1071 if (ret >= 0)
1072 f.file->f_pos = pos;
1073 fdput_pos(f);
1074 return ret;
1075 }
1076
1077 static long __compat_sys_preadv64(unsigned long fd,
1078 const struct compat_iovec __user *vec,
1079 unsigned long vlen, loff_t pos)
1080 {
1081 struct fd f;
1082 ssize_t ret;
1083
1084 if (pos < 0)
1085 return -EINVAL;
1086 f = fdget(fd);
1087 if (!f.file)
1088 return -EBADF;
1089 ret = -ESPIPE;
1090 if (f.file->f_mode & FMODE_PREAD)
1091 ret = compat_readv(f.file, vec, vlen, &pos);
1092 fdput(f);
1093 return ret;
1094 }
1095
1096 #ifdef __ARCH_WANT_COMPAT_SYS_PREADV64
1097 COMPAT_SYSCALL_DEFINE4(preadv64, unsigned long, fd,
1098 const struct compat_iovec __user *,vec,
1099 unsigned long, vlen, loff_t, pos)
1100 {
1101 return __compat_sys_preadv64(fd, vec, vlen, pos);
1102 }
1103 #endif
1104
1105 COMPAT_SYSCALL_DEFINE5(preadv, compat_ulong_t, fd,
1106 const struct compat_iovec __user *,vec,
1107 compat_ulong_t, vlen, u32, pos_low, u32, pos_high)
1108 {
1109 loff_t pos = ((loff_t)pos_high << 32) | pos_low;
1110
1111 return __compat_sys_preadv64(fd, vec, vlen, pos);
1112 }
1113
1114 static size_t compat_writev(struct file *file,
1115 const struct compat_iovec __user *vec,
1116 unsigned long vlen, loff_t *pos)
1117 {
1118 ssize_t ret = -EBADF;
1119
1120 if (!(file->f_mode & FMODE_WRITE))
1121 goto out;
1122
1123 ret = -EINVAL;
1124 if (!(file->f_mode & FMODE_CAN_WRITE))
1125 goto out;
1126
1127 ret = compat_do_readv_writev(WRITE, file, vec, vlen, pos);
1128
1129 out:
1130 if (ret > 0)
1131 add_wchar(current, ret);
1132 inc_syscw(current);
1133 return ret;
1134 }
1135
1136 COMPAT_SYSCALL_DEFINE3(writev, compat_ulong_t, fd,
1137 const struct compat_iovec __user *, vec,
1138 compat_ulong_t, vlen)
1139 {
1140 struct fd f = fdget_pos(fd);
1141 ssize_t ret;
1142 loff_t pos;
1143
1144 if (!f.file)
1145 return -EBADF;
1146 pos = f.file->f_pos;
1147 ret = compat_writev(f.file, vec, vlen, &pos);
1148 if (ret >= 0)
1149 f.file->f_pos = pos;
1150 fdput_pos(f);
1151 return ret;
1152 }
1153
1154 static long __compat_sys_pwritev64(unsigned long fd,
1155 const struct compat_iovec __user *vec,
1156 unsigned long vlen, loff_t pos)
1157 {
1158 struct fd f;
1159 ssize_t ret;
1160
1161 if (pos < 0)
1162 return -EINVAL;
1163 f = fdget(fd);
1164 if (!f.file)
1165 return -EBADF;
1166 ret = -ESPIPE;
1167 if (f.file->f_mode & FMODE_PWRITE)
1168 ret = compat_writev(f.file, vec, vlen, &pos);
1169 fdput(f);
1170 return ret;
1171 }
1172
1173 #ifdef __ARCH_WANT_COMPAT_SYS_PWRITEV64
1174 COMPAT_SYSCALL_DEFINE4(pwritev64, unsigned long, fd,
1175 const struct compat_iovec __user *,vec,
1176 unsigned long, vlen, loff_t, pos)
1177 {
1178 return __compat_sys_pwritev64(fd, vec, vlen, pos);
1179 }
1180 #endif
1181
1182 COMPAT_SYSCALL_DEFINE5(pwritev, compat_ulong_t, fd,
1183 const struct compat_iovec __user *,vec,
1184 compat_ulong_t, vlen, u32, pos_low, u32, pos_high)
1185 {
1186 loff_t pos = ((loff_t)pos_high << 32) | pos_low;
1187
1188 return __compat_sys_pwritev64(fd, vec, vlen, pos);
1189 }
1190 #endif
1191
1192 static ssize_t do_sendfile(int out_fd, int in_fd, loff_t *ppos,
1193 size_t count, loff_t max)
1194 {
1195 struct fd in, out;
1196 struct inode *in_inode, *out_inode;
1197 loff_t pos;
1198 loff_t out_pos;
1199 ssize_t retval;
1200 int fl;
1201
1202 /*
1203 * Get input file, and verify that it is ok..
1204 */
1205 retval = -EBADF;
1206 in = fdget(in_fd);
1207 if (!in.file)
1208 goto out;
1209 if (!(in.file->f_mode & FMODE_READ))
1210 goto fput_in;
1211 retval = -ESPIPE;
1212 if (!ppos) {
1213 pos = in.file->f_pos;
1214 } else {
1215 pos = *ppos;
1216 if (!(in.file->f_mode & FMODE_PREAD))
1217 goto fput_in;
1218 }
1219 retval = rw_verify_area(READ, in.file, &pos, count);
1220 if (retval < 0)
1221 goto fput_in;
1222 count = retval;
1223
1224 /*
1225 * Get output file, and verify that it is ok..
1226 */
1227 retval = -EBADF;
1228 out = fdget(out_fd);
1229 if (!out.file)
1230 goto fput_in;
1231 if (!(out.file->f_mode & FMODE_WRITE))
1232 goto fput_out;
1233 retval = -EINVAL;
1234 in_inode = file_inode(in.file);
1235 out_inode = file_inode(out.file);
1236 out_pos = out.file->f_pos;
1237 retval = rw_verify_area(WRITE, out.file, &out_pos, count);
1238 if (retval < 0)
1239 goto fput_out;
1240 count = retval;
1241
1242 if (!max)
1243 max = min(in_inode->i_sb->s_maxbytes, out_inode->i_sb->s_maxbytes);
1244
1245 if (unlikely(pos + count > max)) {
1246 retval = -EOVERFLOW;
1247 if (pos >= max)
1248 goto fput_out;
1249 count = max - pos;
1250 }
1251
1252 fl = 0;
1253 #if 0
1254 /*
1255 * We need to debate whether we can enable this or not. The
1256 * man page documents EAGAIN return for the output at least,
1257 * and the application is arguably buggy if it doesn't expect
1258 * EAGAIN on a non-blocking file descriptor.
1259 */
1260 if (in.file->f_flags & O_NONBLOCK)
1261 fl = SPLICE_F_NONBLOCK;
1262 #endif
1263 file_start_write(out.file);
1264 retval = do_splice_direct(in.file, &pos, out.file, &out_pos, count, fl);
1265 file_end_write(out.file);
1266
1267 if (retval > 0) {
1268 add_rchar(current, retval);
1269 add_wchar(current, retval);
1270 fsnotify_access(in.file);
1271 fsnotify_modify(out.file);
1272 out.file->f_pos = out_pos;
1273 if (ppos)
1274 *ppos = pos;
1275 else
1276 in.file->f_pos = pos;
1277 }
1278
1279 inc_syscr(current);
1280 inc_syscw(current);
1281 if (pos > max)
1282 retval = -EOVERFLOW;
1283
1284 fput_out:
1285 fdput(out);
1286 fput_in:
1287 fdput(in);
1288 out:
1289 return retval;
1290 }
1291
1292 SYSCALL_DEFINE4(sendfile, int, out_fd, int, in_fd, off_t __user *, offset, size_t, count)
1293 {
1294 loff_t pos;
1295 off_t off;
1296 ssize_t ret;
1297
1298 if (offset) {
1299 if (unlikely(get_user(off, offset)))
1300 return -EFAULT;
1301 pos = off;
1302 ret = do_sendfile(out_fd, in_fd, &pos, count, MAX_NON_LFS);
1303 if (unlikely(put_user(pos, offset)))
1304 return -EFAULT;
1305 return ret;
1306 }
1307
1308 return do_sendfile(out_fd, in_fd, NULL, count, 0);
1309 }
1310
1311 SYSCALL_DEFINE4(sendfile64, int, out_fd, int, in_fd, loff_t __user *, offset, size_t, count)
1312 {
1313 loff_t pos;
1314 ssize_t ret;
1315
1316 if (offset) {
1317 if (unlikely(copy_from_user(&pos, offset, sizeof(loff_t))))
1318 return -EFAULT;
1319 ret = do_sendfile(out_fd, in_fd, &pos, count, 0);
1320 if (unlikely(put_user(pos, offset)))
1321 return -EFAULT;
1322 return ret;
1323 }
1324
1325 return do_sendfile(out_fd, in_fd, NULL, count, 0);
1326 }
1327
1328 #ifdef CONFIG_COMPAT
1329 COMPAT_SYSCALL_DEFINE4(sendfile, int, out_fd, int, in_fd,
1330 compat_off_t __user *, offset, compat_size_t, count)
1331 {
1332 loff_t pos;
1333 off_t off;
1334 ssize_t ret;
1335
1336 if (offset) {
1337 if (unlikely(get_user(off, offset)))
1338 return -EFAULT;
1339 pos = off;
1340 ret = do_sendfile(out_fd, in_fd, &pos, count, MAX_NON_LFS);
1341 if (unlikely(put_user(pos, offset)))
1342 return -EFAULT;
1343 return ret;
1344 }
1345
1346 return do_sendfile(out_fd, in_fd, NULL, count, 0);
1347 }
1348
1349 COMPAT_SYSCALL_DEFINE4(sendfile64, int, out_fd, int, in_fd,
1350 compat_loff_t __user *, offset, compat_size_t, count)
1351 {
1352 loff_t pos;
1353 ssize_t ret;
1354
1355 if (offset) {
1356 if (unlikely(copy_from_user(&pos, offset, sizeof(loff_t))))
1357 return -EFAULT;
1358 ret = do_sendfile(out_fd, in_fd, &pos, count, 0);
1359 if (unlikely(put_user(pos, offset)))
1360 return -EFAULT;
1361 return ret;
1362 }
1363
1364 return do_sendfile(out_fd, in_fd, NULL, count, 0);
1365 }
1366 #endif
Linux kernel - Deliverables
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