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1/*
2 * "splice": joining two ropes together by interweaving their strands.
3 *
4 * This is the "extended pipe" functionality, where a pipe is used as
5 * an arbitrary in-memory buffer. Think of a pipe as a small kernel
6 * buffer that you can use to transfer data from one end to the other.
7 *
8 * The traditional unix read/write is extended with a "splice()" operation
9 * that transfers data buffers to or from a pipe buffer.
10 *
11 * Named by Larry McVoy, original implementation from Linus, extended by
12 * Jens to support splicing to files, network, direct splicing, etc and
13 * fixing lots of bugs.
14 *
15 * Copyright (C) 2005-2006 Jens Axboe <axboe@kernel.dk>
16 * Copyright (C) 2005-2006 Linus Torvalds <torvalds@osdl.org>
17 * Copyright (C) 2006 Ingo Molnar <mingo@elte.hu>
18 *
19 */
20#include <linux/bvec.h>
21#include <linux/fs.h>
22#include <linux/file.h>
23#include <linux/pagemap.h>
24#include <linux/splice.h>
25#include <linux/memcontrol.h>
26#include <linux/mm_inline.h>
27#include <linux/swap.h>
28#include <linux/writeback.h>
29#include <linux/export.h>
30#include <linux/syscalls.h>
31#include <linux/uio.h>
32#include <linux/security.h>
33#include <linux/gfp.h>
34#include <linux/socket.h>
35#include <linux/compat.h>
36#include <linux/sched/signal.h>
37
38#include "internal.h"
39
40/*
41 * Attempt to steal a page from a pipe buffer. This should perhaps go into
42 * a vm helper function, it's already simplified quite a bit by the
43 * addition of remove_mapping(). If success is returned, the caller may
44 * attempt to reuse this page for another destination.
45 */
46static int page_cache_pipe_buf_steal(struct pipe_inode_info *pipe,
47 struct pipe_buffer *buf)
48{
49 struct page *page = buf->page;
50 struct address_space *mapping;
51
52 lock_page(page);
53
54 mapping = page_mapping(page);
55 if (mapping) {
56 WARN_ON(!PageUptodate(page));
57
58 /*
59 * At least for ext2 with nobh option, we need to wait on
60 * writeback completing on this page, since we'll remove it
61 * from the pagecache. Otherwise truncate wont wait on the
62 * page, allowing the disk blocks to be reused by someone else
63 * before we actually wrote our data to them. fs corruption
64 * ensues.
65 */
66 wait_on_page_writeback(page);
67
68 if (page_has_private(page) &&
69 !try_to_release_page(page, GFP_KERNEL))
70 goto out_unlock;
71
72 /*
73 * If we succeeded in removing the mapping, set LRU flag
74 * and return good.
75 */
76 if (remove_mapping(mapping, page)) {
77 buf->flags |= PIPE_BUF_FLAG_LRU;
78 return 0;
79 }
80 }
81
82 /*
83 * Raced with truncate or failed to remove page from current
84 * address space, unlock and return failure.
85 */
86out_unlock:
87 unlock_page(page);
88 return 1;
89}
90
91static void page_cache_pipe_buf_release(struct pipe_inode_info *pipe,
92 struct pipe_buffer *buf)
93{
94 put_page(buf->page);
95 buf->flags &= ~PIPE_BUF_FLAG_LRU;
96}
97
98/*
99 * Check whether the contents of buf is OK to access. Since the content
100 * is a page cache page, IO may be in flight.
101 */
102static int page_cache_pipe_buf_confirm(struct pipe_inode_info *pipe,
103 struct pipe_buffer *buf)
104{
105 struct page *page = buf->page;
106 int err;
107
108 if (!PageUptodate(page)) {
109 lock_page(page);
110
111 /*
112 * Page got truncated/unhashed. This will cause a 0-byte
113 * splice, if this is the first page.
114 */
115 if (!page->mapping) {
116 err = -ENODATA;
117 goto error;
118 }
119
120 /*
121 * Uh oh, read-error from disk.
122 */
123 if (!PageUptodate(page)) {
124 err = -EIO;
125 goto error;
126 }
127
128 /*
129 * Page is ok afterall, we are done.
130 */
131 unlock_page(page);
132 }
133
134 return 0;
135error:
136 unlock_page(page);
137 return err;
138}
139
140const struct pipe_buf_operations page_cache_pipe_buf_ops = {
141 .can_merge = 0,
142 .confirm = page_cache_pipe_buf_confirm,
143 .release = page_cache_pipe_buf_release,
144 .steal = page_cache_pipe_buf_steal,
145 .get = generic_pipe_buf_get,
146};
147
148static int user_page_pipe_buf_steal(struct pipe_inode_info *pipe,
149 struct pipe_buffer *buf)
150{
151 if (!(buf->flags & PIPE_BUF_FLAG_GIFT))
152 return 1;
153
154 buf->flags |= PIPE_BUF_FLAG_LRU;
155 return generic_pipe_buf_steal(pipe, buf);
156}
157
158static const struct pipe_buf_operations user_page_pipe_buf_ops = {
159 .can_merge = 0,
160 .confirm = generic_pipe_buf_confirm,
161 .release = page_cache_pipe_buf_release,
162 .steal = user_page_pipe_buf_steal,
163 .get = generic_pipe_buf_get,
164};
165
166static void wakeup_pipe_readers(struct pipe_inode_info *pipe)
167{
168 smp_mb();
169 if (waitqueue_active(&pipe->wait))
170 wake_up_interruptible(&pipe->wait);
171 kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
172}
173
174/**
175 * splice_to_pipe - fill passed data into a pipe
176 * @pipe: pipe to fill
177 * @spd: data to fill
178 *
179 * Description:
180 * @spd contains a map of pages and len/offset tuples, along with
181 * the struct pipe_buf_operations associated with these pages. This
182 * function will link that data to the pipe.
183 *
184 */
185ssize_t splice_to_pipe(struct pipe_inode_info *pipe,
186 struct splice_pipe_desc *spd)
187{
188 unsigned int spd_pages = spd->nr_pages;
189 int ret = 0, page_nr = 0;
190
191 if (!spd_pages)
192 return 0;
193
194 if (unlikely(!pipe->readers)) {
195 send_sig(SIGPIPE, current, 0);
196 ret = -EPIPE;
197 goto out;
198 }
199
200 while (pipe->nrbufs < pipe->buffers) {
201 int newbuf = (pipe->curbuf + pipe->nrbufs) & (pipe->buffers - 1);
202 struct pipe_buffer *buf = pipe->bufs + newbuf;
203
204 buf->page = spd->pages[page_nr];
205 buf->offset = spd->partial[page_nr].offset;
206 buf->len = spd->partial[page_nr].len;
207 buf->private = spd->partial[page_nr].private;
208 buf->ops = spd->ops;
209 buf->flags = 0;
210
211 pipe->nrbufs++;
212 page_nr++;
213 ret += buf->len;
214
215 if (!--spd->nr_pages)
216 break;
217 }
218
219 if (!ret)
220 ret = -EAGAIN;
221
222out:
223 while (page_nr < spd_pages)
224 spd->spd_release(spd, page_nr++);
225
226 return ret;
227}
228EXPORT_SYMBOL_GPL(splice_to_pipe);
229
230ssize_t add_to_pipe(struct pipe_inode_info *pipe, struct pipe_buffer *buf)
231{
232 int ret;
233
234 if (unlikely(!pipe->readers)) {
235 send_sig(SIGPIPE, current, 0);
236 ret = -EPIPE;
237 } else if (pipe->nrbufs == pipe->buffers) {
238 ret = -EAGAIN;
239 } else {
240 int newbuf = (pipe->curbuf + pipe->nrbufs) & (pipe->buffers - 1);
241 pipe->bufs[newbuf] = *buf;
242 pipe->nrbufs++;
243 return buf->len;
244 }
245 pipe_buf_release(pipe, buf);
246 return ret;
247}
248EXPORT_SYMBOL(add_to_pipe);
249
250/*
251 * Check if we need to grow the arrays holding pages and partial page
252 * descriptions.
253 */
254int splice_grow_spd(const struct pipe_inode_info *pipe, struct splice_pipe_desc *spd)
255{
256 unsigned int buffers = READ_ONCE(pipe->buffers);
257
258 spd->nr_pages_max = buffers;
259 if (buffers <= PIPE_DEF_BUFFERS)
260 return 0;
261
262 spd->pages = kmalloc(buffers * sizeof(struct page *), GFP_KERNEL);
263 spd->partial = kmalloc(buffers * sizeof(struct partial_page), GFP_KERNEL);
264
265 if (spd->pages && spd->partial)
266 return 0;
267
268 kfree(spd->pages);
269 kfree(spd->partial);
270 return -ENOMEM;
271}
272
273void splice_shrink_spd(struct splice_pipe_desc *spd)
274{
275 if (spd->nr_pages_max <= PIPE_DEF_BUFFERS)
276 return;
277
278 kfree(spd->pages);
279 kfree(spd->partial);
280}
281
282/**
283 * generic_file_splice_read - splice data from file to a pipe
284 * @in: file to splice from
285 * @ppos: position in @in
286 * @pipe: pipe to splice to
287 * @len: number of bytes to splice
288 * @flags: splice modifier flags
289 *
290 * Description:
291 * Will read pages from given file and fill them into a pipe. Can be
292 * used as long as it has more or less sane ->read_iter().
293 *
294 */
295ssize_t generic_file_splice_read(struct file *in, loff_t *ppos,
296 struct pipe_inode_info *pipe, size_t len,
297 unsigned int flags)
298{
299 struct iov_iter to;
300 struct kiocb kiocb;
301 int idx, ret;
302
303 iov_iter_pipe(&to, ITER_PIPE | READ, pipe, len);
304 idx = to.idx;
305 init_sync_kiocb(&kiocb, in);
306 kiocb.ki_pos = *ppos;
307 ret = call_read_iter(in, &kiocb, &to);
308 if (ret > 0) {
309 *ppos = kiocb.ki_pos;
310 file_accessed(in);
311 } else if (ret < 0) {
312 to.idx = idx;
313 to.iov_offset = 0;
314 iov_iter_advance(&to, 0); /* to free what was emitted */
315 /*
316 * callers of ->splice_read() expect -EAGAIN on
317 * "can't put anything in there", rather than -EFAULT.
318 */
319 if (ret == -EFAULT)
320 ret = -EAGAIN;
321 }
322
323 return ret;
324}
325EXPORT_SYMBOL(generic_file_splice_read);
326
327const struct pipe_buf_operations default_pipe_buf_ops = {
328 .can_merge = 0,
329 .confirm = generic_pipe_buf_confirm,
330 .release = generic_pipe_buf_release,
331 .steal = generic_pipe_buf_steal,
332 .get = generic_pipe_buf_get,
333};
334
335static int generic_pipe_buf_nosteal(struct pipe_inode_info *pipe,
336 struct pipe_buffer *buf)
337{
338 return 1;
339}
340
341/* Pipe buffer operations for a socket and similar. */
342const struct pipe_buf_operations nosteal_pipe_buf_ops = {
343 .can_merge = 0,
344 .confirm = generic_pipe_buf_confirm,
345 .release = generic_pipe_buf_release,
346 .steal = generic_pipe_buf_nosteal,
347 .get = generic_pipe_buf_get,
348};
349EXPORT_SYMBOL(nosteal_pipe_buf_ops);
350
351static ssize_t kernel_readv(struct file *file, const struct kvec *vec,
352 unsigned long vlen, loff_t offset)
353{
354 mm_segment_t old_fs;
355 loff_t pos = offset;
356 ssize_t res;
357
358 old_fs = get_fs();
359 set_fs(get_ds());
360 /* The cast to a user pointer is valid due to the set_fs() */
361 res = vfs_readv(file, (const struct iovec __user *)vec, vlen, &pos, 0);
362 set_fs(old_fs);
363
364 return res;
365}
366
367static ssize_t default_file_splice_read(struct file *in, loff_t *ppos,
368 struct pipe_inode_info *pipe, size_t len,
369 unsigned int flags)
370{
371 struct kvec *vec, __vec[PIPE_DEF_BUFFERS];
372 struct iov_iter to;
373 struct page **pages;
374 unsigned int nr_pages;
375 size_t offset, base, copied = 0;
376 ssize_t res;
377 int i;
378
379 if (pipe->nrbufs == pipe->buffers)
380 return -EAGAIN;
381
382 /*
383 * Try to keep page boundaries matching to source pagecache ones -
384 * it probably won't be much help, but...
385 */
386 offset = *ppos & ~PAGE_MASK;
387
388 iov_iter_pipe(&to, ITER_PIPE | READ, pipe, len + offset);
389
390 res = iov_iter_get_pages_alloc(&to, &pages, len + offset, &base);
391 if (res <= 0)
392 return -ENOMEM;
393
394 nr_pages = DIV_ROUND_UP(res + base, PAGE_SIZE);
395
396 vec = __vec;
397 if (nr_pages > PIPE_DEF_BUFFERS) {
398 vec = kmalloc(nr_pages * sizeof(struct kvec), GFP_KERNEL);
399 if (unlikely(!vec)) {
400 res = -ENOMEM;
401 goto out;
402 }
403 }
404
405 pipe->bufs[to.idx].offset = offset;
406 pipe->bufs[to.idx].len -= offset;
407
408 for (i = 0; i < nr_pages; i++) {
409 size_t this_len = min_t(size_t, len, PAGE_SIZE - offset);
410 vec[i].iov_base = page_address(pages[i]) + offset;
411 vec[i].iov_len = this_len;
412 len -= this_len;
413 offset = 0;
414 }
415
416 res = kernel_readv(in, vec, nr_pages, *ppos);
417 if (res > 0) {
418 copied = res;
419 *ppos += res;
420 }
421
422 if (vec != __vec)
423 kfree(vec);
424out:
425 for (i = 0; i < nr_pages; i++)
426 put_page(pages[i]);
427 kvfree(pages);
428 iov_iter_advance(&to, copied); /* truncates and discards */
429 return res;
430}
431
432/*
433 * Send 'sd->len' bytes to socket from 'sd->file' at position 'sd->pos'
434 * using sendpage(). Return the number of bytes sent.
435 */
436static int pipe_to_sendpage(struct pipe_inode_info *pipe,
437 struct pipe_buffer *buf, struct splice_desc *sd)
438{
439 struct file *file = sd->u.file;
440 loff_t pos = sd->pos;
441 int more;
442
443 if (!likely(file->f_op->sendpage))
444 return -EINVAL;
445
446 more = (sd->flags & SPLICE_F_MORE) ? MSG_MORE : 0;
447
448 if (sd->len < sd->total_len && pipe->nrbufs > 1)
449 more |= MSG_SENDPAGE_NOTLAST;
450
451 return file->f_op->sendpage(file, buf->page, buf->offset,
452 sd->len, &pos, more);
453}
454
455static void wakeup_pipe_writers(struct pipe_inode_info *pipe)
456{
457 smp_mb();
458 if (waitqueue_active(&pipe->wait))
459 wake_up_interruptible(&pipe->wait);
460 kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT);
461}
462
463/**
464 * splice_from_pipe_feed - feed available data from a pipe to a file
465 * @pipe: pipe to splice from
466 * @sd: information to @actor
467 * @actor: handler that splices the data
468 *
469 * Description:
470 * This function loops over the pipe and calls @actor to do the
471 * actual moving of a single struct pipe_buffer to the desired
472 * destination. It returns when there's no more buffers left in
473 * the pipe or if the requested number of bytes (@sd->total_len)
474 * have been copied. It returns a positive number (one) if the
475 * pipe needs to be filled with more data, zero if the required
476 * number of bytes have been copied and -errno on error.
477 *
478 * This, together with splice_from_pipe_{begin,end,next}, may be
479 * used to implement the functionality of __splice_from_pipe() when
480 * locking is required around copying the pipe buffers to the
481 * destination.
482 */
483static int splice_from_pipe_feed(struct pipe_inode_info *pipe, struct splice_desc *sd,
484 splice_actor *actor)
485{
486 int ret;
487
488 while (pipe->nrbufs) {
489 struct pipe_buffer *buf = pipe->bufs + pipe->curbuf;
490
491 sd->len = buf->len;
492 if (sd->len > sd->total_len)
493 sd->len = sd->total_len;
494
495 ret = pipe_buf_confirm(pipe, buf);
496 if (unlikely(ret)) {
497 if (ret == -ENODATA)
498 ret = 0;
499 return ret;
500 }
501
502 ret = actor(pipe, buf, sd);
503 if (ret <= 0)
504 return ret;
505
506 buf->offset += ret;
507 buf->len -= ret;
508
509 sd->num_spliced += ret;
510 sd->len -= ret;
511 sd->pos += ret;
512 sd->total_len -= ret;
513
514 if (!buf->len) {
515 pipe_buf_release(pipe, buf);
516 pipe->curbuf = (pipe->curbuf + 1) & (pipe->buffers - 1);
517 pipe->nrbufs--;
518 if (pipe->files)
519 sd->need_wakeup = true;
520 }
521
522 if (!sd->total_len)
523 return 0;
524 }
525
526 return 1;
527}
528
529/**
530 * splice_from_pipe_next - wait for some data to splice from
531 * @pipe: pipe to splice from
532 * @sd: information about the splice operation
533 *
534 * Description:
535 * This function will wait for some data and return a positive
536 * value (one) if pipe buffers are available. It will return zero
537 * or -errno if no more data needs to be spliced.
538 */
539static int splice_from_pipe_next(struct pipe_inode_info *pipe, struct splice_desc *sd)
540{
541 /*
542 * Check for signal early to make process killable when there are
543 * always buffers available
544 */
545 if (signal_pending(current))
546 return -ERESTARTSYS;
547
548 while (!pipe->nrbufs) {
549 if (!pipe->writers)
550 return 0;
551
552 if (!pipe->waiting_writers && sd->num_spliced)
553 return 0;
554
555 if (sd->flags & SPLICE_F_NONBLOCK)
556 return -EAGAIN;
557
558 if (signal_pending(current))
559 return -ERESTARTSYS;
560
561 if (sd->need_wakeup) {
562 wakeup_pipe_writers(pipe);
563 sd->need_wakeup = false;
564 }
565
566 pipe_wait(pipe);
567 }
568
569 return 1;
570}
571
572/**
573 * splice_from_pipe_begin - start splicing from pipe
574 * @sd: information about the splice operation
575 *
576 * Description:
577 * This function should be called before a loop containing
578 * splice_from_pipe_next() and splice_from_pipe_feed() to
579 * initialize the necessary fields of @sd.
580 */
581static void splice_from_pipe_begin(struct splice_desc *sd)
582{
583 sd->num_spliced = 0;
584 sd->need_wakeup = false;
585}
586
587/**
588 * splice_from_pipe_end - finish splicing from pipe
589 * @pipe: pipe to splice from
590 * @sd: information about the splice operation
591 *
592 * Description:
593 * This function will wake up pipe writers if necessary. It should
594 * be called after a loop containing splice_from_pipe_next() and
595 * splice_from_pipe_feed().
596 */
597static void splice_from_pipe_end(struct pipe_inode_info *pipe, struct splice_desc *sd)
598{
599 if (sd->need_wakeup)
600 wakeup_pipe_writers(pipe);
601}
602
603/**
604 * __splice_from_pipe - splice data from a pipe to given actor
605 * @pipe: pipe to splice from
606 * @sd: information to @actor
607 * @actor: handler that splices the data
608 *
609 * Description:
610 * This function does little more than loop over the pipe and call
611 * @actor to do the actual moving of a single struct pipe_buffer to
612 * the desired destination. See pipe_to_file, pipe_to_sendpage, or
613 * pipe_to_user.
614 *
615 */
616ssize_t __splice_from_pipe(struct pipe_inode_info *pipe, struct splice_desc *sd,
617 splice_actor *actor)
618{
619 int ret;
620
621 splice_from_pipe_begin(sd);
622 do {
623 cond_resched();
624 ret = splice_from_pipe_next(pipe, sd);
625 if (ret > 0)
626 ret = splice_from_pipe_feed(pipe, sd, actor);
627 } while (ret > 0);
628 splice_from_pipe_end(pipe, sd);
629
630 return sd->num_spliced ? sd->num_spliced : ret;
631}
632EXPORT_SYMBOL(__splice_from_pipe);
633
634/**
635 * splice_from_pipe - splice data from a pipe to a file
636 * @pipe: pipe to splice from
637 * @out: file to splice to
638 * @ppos: position in @out
639 * @len: how many bytes to splice
640 * @flags: splice modifier flags
641 * @actor: handler that splices the data
642 *
643 * Description:
644 * See __splice_from_pipe. This function locks the pipe inode,
645 * otherwise it's identical to __splice_from_pipe().
646 *
647 */
648ssize_t splice_from_pipe(struct pipe_inode_info *pipe, struct file *out,
649 loff_t *ppos, size_t len, unsigned int flags,
650 splice_actor *actor)
651{
652 ssize_t ret;
653 struct splice_desc sd = {
654 .total_len = len,
655 .flags = flags,
656 .pos = *ppos,
657 .u.file = out,
658 };
659
660 pipe_lock(pipe);
661 ret = __splice_from_pipe(pipe, &sd, actor);
662 pipe_unlock(pipe);
663
664 return ret;
665}
666
667/**
668 * iter_file_splice_write - splice data from a pipe to a file
669 * @pipe: pipe info
670 * @out: file to write to
671 * @ppos: position in @out
672 * @len: number of bytes to splice
673 * @flags: splice modifier flags
674 *
675 * Description:
676 * Will either move or copy pages (determined by @flags options) from
677 * the given pipe inode to the given file.
678 * This one is ->write_iter-based.
679 *
680 */
681ssize_t
682iter_file_splice_write(struct pipe_inode_info *pipe, struct file *out,
683 loff_t *ppos, size_t len, unsigned int flags)
684{
685 struct splice_desc sd = {
686 .total_len = len,
687 .flags = flags,
688 .pos = *ppos,
689 .u.file = out,
690 };
691 int nbufs = pipe->buffers;
692 struct bio_vec *array = kcalloc(nbufs, sizeof(struct bio_vec),
693 GFP_KERNEL);
694 ssize_t ret;
695
696 if (unlikely(!array))
697 return -ENOMEM;
698
699 pipe_lock(pipe);
700
701 splice_from_pipe_begin(&sd);
702 while (sd.total_len) {
703 struct iov_iter from;
704 size_t left;
705 int n, idx;
706
707 ret = splice_from_pipe_next(pipe, &sd);
708 if (ret <= 0)
709 break;
710
711 if (unlikely(nbufs < pipe->buffers)) {
712 kfree(array);
713 nbufs = pipe->buffers;
714 array = kcalloc(nbufs, sizeof(struct bio_vec),
715 GFP_KERNEL);
716 if (!array) {
717 ret = -ENOMEM;
718 break;
719 }
720 }
721
722 /* build the vector */
723 left = sd.total_len;
724 for (n = 0, idx = pipe->curbuf; left && n < pipe->nrbufs; n++, idx++) {
725 struct pipe_buffer *buf = pipe->bufs + idx;
726 size_t this_len = buf->len;
727
728 if (this_len > left)
729 this_len = left;
730
731 if (idx == pipe->buffers - 1)
732 idx = -1;
733
734 ret = pipe_buf_confirm(pipe, buf);
735 if (unlikely(ret)) {
736 if (ret == -ENODATA)
737 ret = 0;
738 goto done;
739 }
740
741 array[n].bv_page = buf->page;
742 array[n].bv_len = this_len;
743 array[n].bv_offset = buf->offset;
744 left -= this_len;
745 }
746
747 iov_iter_bvec(&from, ITER_BVEC | WRITE, array, n,
748 sd.total_len - left);
749 ret = vfs_iter_write(out, &from, &sd.pos, 0);
750 if (ret <= 0)
751 break;
752
753 sd.num_spliced += ret;
754 sd.total_len -= ret;
755 *ppos = sd.pos;
756
757 /* dismiss the fully eaten buffers, adjust the partial one */
758 while (ret) {
759 struct pipe_buffer *buf = pipe->bufs + pipe->curbuf;
760 if (ret >= buf->len) {
761 ret -= buf->len;
762 buf->len = 0;
763 pipe_buf_release(pipe, buf);
764 pipe->curbuf = (pipe->curbuf + 1) & (pipe->buffers - 1);
765 pipe->nrbufs--;
766 if (pipe->files)
767 sd.need_wakeup = true;
768 } else {
769 buf->offset += ret;
770 buf->len -= ret;
771 ret = 0;
772 }
773 }
774 }
775done:
776 kfree(array);
777 splice_from_pipe_end(pipe, &sd);
778
779 pipe_unlock(pipe);
780
781 if (sd.num_spliced)
782 ret = sd.num_spliced;
783
784 return ret;
785}
786
787EXPORT_SYMBOL(iter_file_splice_write);
788
789static int write_pipe_buf(struct pipe_inode_info *pipe, struct pipe_buffer *buf,
790 struct splice_desc *sd)
791{
792 int ret;
793 void *data;
794 loff_t tmp = sd->pos;
795
796 data = kmap(buf->page);
797 ret = __kernel_write(sd->u.file, data + buf->offset, sd->len, &tmp);
798 kunmap(buf->page);
799
800 return ret;
801}
802
803static ssize_t default_file_splice_write(struct pipe_inode_info *pipe,
804 struct file *out, loff_t *ppos,
805 size_t len, unsigned int flags)
806{
807 ssize_t ret;
808
809 ret = splice_from_pipe(pipe, out, ppos, len, flags, write_pipe_buf);
810 if (ret > 0)
811 *ppos += ret;
812
813 return ret;
814}
815
816/**
817 * generic_splice_sendpage - splice data from a pipe to a socket
818 * @pipe: pipe to splice from
819 * @out: socket to write to
820 * @ppos: position in @out
821 * @len: number of bytes to splice
822 * @flags: splice modifier flags
823 *
824 * Description:
825 * Will send @len bytes from the pipe to a network socket. No data copying
826 * is involved.
827 *
828 */
829ssize_t generic_splice_sendpage(struct pipe_inode_info *pipe, struct file *out,
830 loff_t *ppos, size_t len, unsigned int flags)
831{
832 return splice_from_pipe(pipe, out, ppos, len, flags, pipe_to_sendpage);
833}
834
835EXPORT_SYMBOL(generic_splice_sendpage);
836
837/*
838 * Attempt to initiate a splice from pipe to file.
839 */
840static long do_splice_from(struct pipe_inode_info *pipe, struct file *out,
841 loff_t *ppos, size_t len, unsigned int flags)
842{
843 ssize_t (*splice_write)(struct pipe_inode_info *, struct file *,
844 loff_t *, size_t, unsigned int);
845
846 if (out->f_op->splice_write)
847 splice_write = out->f_op->splice_write;
848 else
849 splice_write = default_file_splice_write;
850
851 return splice_write(pipe, out, ppos, len, flags);
852}
853
854/*
855 * Attempt to initiate a splice from a file to a pipe.
856 */
857static long do_splice_to(struct file *in, loff_t *ppos,
858 struct pipe_inode_info *pipe, size_t len,
859 unsigned int flags)
860{
861 ssize_t (*splice_read)(struct file *, loff_t *,
862 struct pipe_inode_info *, size_t, unsigned int);
863 int ret;
864
865 if (unlikely(!(in->f_mode & FMODE_READ)))
866 return -EBADF;
867
868 ret = rw_verify_area(READ, in, ppos, len);
869 if (unlikely(ret < 0))
870 return ret;
871
872 if (unlikely(len > MAX_RW_COUNT))
873 len = MAX_RW_COUNT;
874
875 if (in->f_op->splice_read)
876 splice_read = in->f_op->splice_read;
877 else
878 splice_read = default_file_splice_read;
879
880 return splice_read(in, ppos, pipe, len, flags);
881}
882
883/**
884 * splice_direct_to_actor - splices data directly between two non-pipes
885 * @in: file to splice from
886 * @sd: actor information on where to splice to
887 * @actor: handles the data splicing
888 *
889 * Description:
890 * This is a special case helper to splice directly between two
891 * points, without requiring an explicit pipe. Internally an allocated
892 * pipe is cached in the process, and reused during the lifetime of
893 * that process.
894 *
895 */
896ssize_t splice_direct_to_actor(struct file *in, struct splice_desc *sd,
897 splice_direct_actor *actor)
898{
899 struct pipe_inode_info *pipe;
900 long ret, bytes;
901 umode_t i_mode;
902 size_t len;
903 int i, flags, more;
904
905 /*
906 * We require the input being a regular file, as we don't want to
907 * randomly drop data for eg socket -> socket splicing. Use the
908 * piped splicing for that!
909 */
910 i_mode = file_inode(in)->i_mode;
911 if (unlikely(!S_ISREG(i_mode) && !S_ISBLK(i_mode)))
912 return -EINVAL;
913
914 /*
915 * neither in nor out is a pipe, setup an internal pipe attached to
916 * 'out' and transfer the wanted data from 'in' to 'out' through that
917 */
918 pipe = current->splice_pipe;
919 if (unlikely(!pipe)) {
920 pipe = alloc_pipe_info();
921 if (!pipe)
922 return -ENOMEM;
923
924 /*
925 * We don't have an immediate reader, but we'll read the stuff
926 * out of the pipe right after the splice_to_pipe(). So set
927 * PIPE_READERS appropriately.
928 */
929 pipe->readers = 1;
930
931 current->splice_pipe = pipe;
932 }
933
934 /*
935 * Do the splice.
936 */
937 ret = 0;
938 bytes = 0;
939 len = sd->total_len;
940 flags = sd->flags;
941
942 /*
943 * Don't block on output, we have to drain the direct pipe.
944 */
945 sd->flags &= ~SPLICE_F_NONBLOCK;
946 more = sd->flags & SPLICE_F_MORE;
947
948 while (len) {
949 size_t read_len;
950 loff_t pos = sd->pos, prev_pos = pos;
951
952 ret = do_splice_to(in, &pos, pipe, len, flags);
953 if (unlikely(ret <= 0))
954 goto out_release;
955
956 read_len = ret;
957 sd->total_len = read_len;
958
959 /*
960 * If more data is pending, set SPLICE_F_MORE
961 * If this is the last data and SPLICE_F_MORE was not set
962 * initially, clears it.
963 */
964 if (read_len < len)
965 sd->flags |= SPLICE_F_MORE;
966 else if (!more)
967 sd->flags &= ~SPLICE_F_MORE;
968 /*
969 * NOTE: nonblocking mode only applies to the input. We
970 * must not do the output in nonblocking mode as then we
971 * could get stuck data in the internal pipe:
972 */
973 ret = actor(pipe, sd);
974 if (unlikely(ret <= 0)) {
975 sd->pos = prev_pos;
976 goto out_release;
977 }
978
979 bytes += ret;
980 len -= ret;
981 sd->pos = pos;
982
983 if (ret < read_len) {
984 sd->pos = prev_pos + ret;
985 goto out_release;
986 }
987 }
988
989done:
990 pipe->nrbufs = pipe->curbuf = 0;
991 file_accessed(in);
992 return bytes;
993
994out_release:
995 /*
996 * If we did an incomplete transfer we must release
997 * the pipe buffers in question:
998 */
999 for (i = 0; i < pipe->buffers; i++) {
1000 struct pipe_buffer *buf = pipe->bufs + i;
1001
1002 if (buf->ops)
1003 pipe_buf_release(pipe, buf);
1004 }
1005
1006 if (!bytes)
1007 bytes = ret;
1008
1009 goto done;
1010}
1011EXPORT_SYMBOL(splice_direct_to_actor);
1012
1013static int direct_splice_actor(struct pipe_inode_info *pipe,
1014 struct splice_desc *sd)
1015{
1016 struct file *file = sd->u.file;
1017
1018 return do_splice_from(pipe, file, sd->opos, sd->total_len,
1019 sd->flags);
1020}
1021
1022/**
1023 * do_splice_direct - splices data directly between two files
1024 * @in: file to splice from
1025 * @ppos: input file offset
1026 * @out: file to splice to
1027 * @opos: output file offset
1028 * @len: number of bytes to splice
1029 * @flags: splice modifier flags
1030 *
1031 * Description:
1032 * For use by do_sendfile(). splice can easily emulate sendfile, but
1033 * doing it in the application would incur an extra system call
1034 * (splice in + splice out, as compared to just sendfile()). So this helper
1035 * can splice directly through a process-private pipe.
1036 *
1037 */
1038long do_splice_direct(struct file *in, loff_t *ppos, struct file *out,
1039 loff_t *opos, size_t len, unsigned int flags)
1040{
1041 struct splice_desc sd = {
1042 .len = len,
1043 .total_len = len,
1044 .flags = flags,
1045 .pos = *ppos,
1046 .u.file = out,
1047 .opos = opos,
1048 };
1049 long ret;
1050
1051 if (unlikely(!(out->f_mode & FMODE_WRITE)))
1052 return -EBADF;
1053
1054 if (unlikely(out->f_flags & O_APPEND))
1055 return -EINVAL;
1056
1057 ret = rw_verify_area(WRITE, out, opos, len);
1058 if (unlikely(ret < 0))
1059 return ret;
1060
1061 ret = splice_direct_to_actor(in, &sd, direct_splice_actor);
1062 if (ret > 0)
1063 *ppos = sd.pos;
1064
1065 return ret;
1066}
1067EXPORT_SYMBOL(do_splice_direct);
1068
1069static int wait_for_space(struct pipe_inode_info *pipe, unsigned flags)
1070{
1071 for (;;) {
1072 if (unlikely(!pipe->readers)) {
1073 send_sig(SIGPIPE, current, 0);
1074 return -EPIPE;
1075 }
1076 if (pipe->nrbufs != pipe->buffers)
1077 return 0;
1078 if (flags & SPLICE_F_NONBLOCK)
1079 return -EAGAIN;
1080 if (signal_pending(current))
1081 return -ERESTARTSYS;
1082 pipe->waiting_writers++;
1083 pipe_wait(pipe);
1084 pipe->waiting_writers--;
1085 }
1086}
1087
1088static int splice_pipe_to_pipe(struct pipe_inode_info *ipipe,
1089 struct pipe_inode_info *opipe,
1090 size_t len, unsigned int flags);
1091
1092/*
1093 * Determine where to splice to/from.
1094 */
1095static long do_splice(struct file *in, loff_t __user *off_in,
1096 struct file *out, loff_t __user *off_out,
1097 size_t len, unsigned int flags)
1098{
1099 struct pipe_inode_info *ipipe;
1100 struct pipe_inode_info *opipe;
1101 loff_t offset;
1102 long ret;
1103
1104 ipipe = get_pipe_info(in);
1105 opipe = get_pipe_info(out);
1106
1107 if (ipipe && opipe) {
1108 if (off_in || off_out)
1109 return -ESPIPE;
1110
1111 if (!(in->f_mode & FMODE_READ))
1112 return -EBADF;
1113
1114 if (!(out->f_mode & FMODE_WRITE))
1115 return -EBADF;
1116
1117 /* Splicing to self would be fun, but... */
1118 if (ipipe == opipe)
1119 return -EINVAL;
1120
1121 return splice_pipe_to_pipe(ipipe, opipe, len, flags);
1122 }
1123
1124 if (ipipe) {
1125 if (off_in)
1126 return -ESPIPE;
1127 if (off_out) {
1128 if (!(out->f_mode & FMODE_PWRITE))
1129 return -EINVAL;
1130 if (copy_from_user(&offset, off_out, sizeof(loff_t)))
1131 return -EFAULT;
1132 } else {
1133 offset = out->f_pos;
1134 }
1135
1136 if (unlikely(!(out->f_mode & FMODE_WRITE)))
1137 return -EBADF;
1138
1139 if (unlikely(out->f_flags & O_APPEND))
1140 return -EINVAL;
1141
1142 ret = rw_verify_area(WRITE, out, &offset, len);
1143 if (unlikely(ret < 0))
1144 return ret;
1145
1146 file_start_write(out);
1147 ret = do_splice_from(ipipe, out, &offset, len, flags);
1148 file_end_write(out);
1149
1150 if (!off_out)
1151 out->f_pos = offset;
1152 else if (copy_to_user(off_out, &offset, sizeof(loff_t)))
1153 ret = -EFAULT;
1154
1155 return ret;
1156 }
1157
1158 if (opipe) {
1159 if (off_out)
1160 return -ESPIPE;
1161 if (off_in) {
1162 if (!(in->f_mode & FMODE_PREAD))
1163 return -EINVAL;
1164 if (copy_from_user(&offset, off_in, sizeof(loff_t)))
1165 return -EFAULT;
1166 } else {
1167 offset = in->f_pos;
1168 }
1169
1170 pipe_lock(opipe);
1171 ret = wait_for_space(opipe, flags);
1172 if (!ret)
1173 ret = do_splice_to(in, &offset, opipe, len, flags);
1174 pipe_unlock(opipe);
1175 if (ret > 0)
1176 wakeup_pipe_readers(opipe);
1177 if (!off_in)
1178 in->f_pos = offset;
1179 else if (copy_to_user(off_in, &offset, sizeof(loff_t)))
1180 ret = -EFAULT;
1181
1182 return ret;
1183 }
1184
1185 return -EINVAL;
1186}
1187
1188static int iter_to_pipe(struct iov_iter *from,
1189 struct pipe_inode_info *pipe,
1190 unsigned flags)
1191{
1192 struct pipe_buffer buf = {
1193 .ops = &user_page_pipe_buf_ops,
1194 .flags = flags
1195 };
1196 size_t total = 0;
1197 int ret = 0;
1198 bool failed = false;
1199
1200 while (iov_iter_count(from) && !failed) {
1201 struct page *pages[16];
1202 ssize_t copied;
1203 size_t start;
1204 int n;
1205
1206 copied = iov_iter_get_pages(from, pages, ~0UL, 16, &start);
1207 if (copied <= 0) {
1208 ret = copied;
1209 break;
1210 }
1211
1212 for (n = 0; copied; n++, start = 0) {
1213 int size = min_t(int, copied, PAGE_SIZE - start);
1214 if (!failed) {
1215 buf.page = pages[n];
1216 buf.offset = start;
1217 buf.len = size;
1218 ret = add_to_pipe(pipe, &buf);
1219 if (unlikely(ret < 0)) {
1220 failed = true;
1221 } else {
1222 iov_iter_advance(from, ret);
1223 total += ret;
1224 }
1225 } else {
1226 put_page(pages[n]);
1227 }
1228 copied -= size;
1229 }
1230 }
1231 return total ? total : ret;
1232}
1233
1234static int pipe_to_user(struct pipe_inode_info *pipe, struct pipe_buffer *buf,
1235 struct splice_desc *sd)
1236{
1237 int n = copy_page_to_iter(buf->page, buf->offset, sd->len, sd->u.data);
1238 return n == sd->len ? n : -EFAULT;
1239}
1240
1241/*
1242 * For lack of a better implementation, implement vmsplice() to userspace
1243 * as a simple copy of the pipes pages to the user iov.
1244 */
1245static long vmsplice_to_user(struct file *file, const struct iovec __user *uiov,
1246 unsigned long nr_segs, unsigned int flags)
1247{
1248 struct pipe_inode_info *pipe;
1249 struct splice_desc sd;
1250 long ret;
1251 struct iovec iovstack[UIO_FASTIOV];
1252 struct iovec *iov = iovstack;
1253 struct iov_iter iter;
1254
1255 pipe = get_pipe_info(file);
1256 if (!pipe)
1257 return -EBADF;
1258
1259 ret = import_iovec(READ, uiov, nr_segs,
1260 ARRAY_SIZE(iovstack), &iov, &iter);
1261 if (ret < 0)
1262 return ret;
1263
1264 sd.total_len = iov_iter_count(&iter);
1265 sd.len = 0;
1266 sd.flags = flags;
1267 sd.u.data = &iter;
1268 sd.pos = 0;
1269
1270 if (sd.total_len) {
1271 pipe_lock(pipe);
1272 ret = __splice_from_pipe(pipe, &sd, pipe_to_user);
1273 pipe_unlock(pipe);
1274 }
1275
1276 kfree(iov);
1277 return ret;
1278}
1279
1280/*
1281 * vmsplice splices a user address range into a pipe. It can be thought of
1282 * as splice-from-memory, where the regular splice is splice-from-file (or
1283 * to file). In both cases the output is a pipe, naturally.
1284 */
1285static long vmsplice_to_pipe(struct file *file, const struct iovec __user *uiov,
1286 unsigned long nr_segs, unsigned int flags)
1287{
1288 struct pipe_inode_info *pipe;
1289 struct iovec iovstack[UIO_FASTIOV];
1290 struct iovec *iov = iovstack;
1291 struct iov_iter from;
1292 long ret;
1293 unsigned buf_flag = 0;
1294
1295 if (flags & SPLICE_F_GIFT)
1296 buf_flag = PIPE_BUF_FLAG_GIFT;
1297
1298 pipe = get_pipe_info(file);
1299 if (!pipe)
1300 return -EBADF;
1301
1302 ret = import_iovec(WRITE, uiov, nr_segs,
1303 ARRAY_SIZE(iovstack), &iov, &from);
1304 if (ret < 0)
1305 return ret;
1306
1307 pipe_lock(pipe);
1308 ret = wait_for_space(pipe, flags);
1309 if (!ret)
1310 ret = iter_to_pipe(&from, pipe, buf_flag);
1311 pipe_unlock(pipe);
1312 if (ret > 0)
1313 wakeup_pipe_readers(pipe);
1314 kfree(iov);
1315 return ret;
1316}
1317
1318/*
1319 * Note that vmsplice only really supports true splicing _from_ user memory
1320 * to a pipe, not the other way around. Splicing from user memory is a simple
1321 * operation that can be supported without any funky alignment restrictions
1322 * or nasty vm tricks. We simply map in the user memory and fill them into
1323 * a pipe. The reverse isn't quite as easy, though. There are two possible
1324 * solutions for that:
1325 *
1326 * - memcpy() the data internally, at which point we might as well just
1327 * do a regular read() on the buffer anyway.
1328 * - Lots of nasty vm tricks, that are neither fast nor flexible (it
1329 * has restriction limitations on both ends of the pipe).
1330 *
1331 * Currently we punt and implement it as a normal copy, see pipe_to_user().
1332 *
1333 */
1334static long do_vmsplice(int fd, const struct iovec __user *iov,
1335 unsigned long nr_segs, unsigned int flags)
1336{
1337 struct fd f;
1338 long error;
1339
1340 if (unlikely(flags & ~SPLICE_F_ALL))
1341 return -EINVAL;
1342 if (unlikely(nr_segs > UIO_MAXIOV))
1343 return -EINVAL;
1344 else if (unlikely(!nr_segs))
1345 return 0;
1346
1347 error = -EBADF;
1348 f = fdget(fd);
1349 if (f.file) {
1350 if (f.file->f_mode & FMODE_WRITE)
1351 error = vmsplice_to_pipe(f.file, iov, nr_segs, flags);
1352 else if (f.file->f_mode & FMODE_READ)
1353 error = vmsplice_to_user(f.file, iov, nr_segs, flags);
1354
1355 fdput(f);
1356 }
1357
1358 return error;
1359}
1360
1361SYSCALL_DEFINE4(vmsplice, int, fd, const struct iovec __user *, iov,
1362 unsigned long, nr_segs, unsigned int, flags)
1363{
1364 return do_vmsplice(fd, iov, nr_segs, flags);
1365}
1366
1367#ifdef CONFIG_COMPAT
1368COMPAT_SYSCALL_DEFINE4(vmsplice, int, fd, const struct compat_iovec __user *, iov32,
1369 unsigned int, nr_segs, unsigned int, flags)
1370{
1371 unsigned i;
1372 struct iovec __user *iov;
1373 if (nr_segs > UIO_MAXIOV)
1374 return -EINVAL;
1375 iov = compat_alloc_user_space(nr_segs * sizeof(struct iovec));
1376 for (i = 0; i < nr_segs; i++) {
1377 struct compat_iovec v;
1378 if (get_user(v.iov_base, &iov32[i].iov_base) ||
1379 get_user(v.iov_len, &iov32[i].iov_len) ||
1380 put_user(compat_ptr(v.iov_base), &iov[i].iov_base) ||
1381 put_user(v.iov_len, &iov[i].iov_len))
1382 return -EFAULT;
1383 }
1384 return do_vmsplice(fd, iov, nr_segs, flags);
1385}
1386#endif
1387
1388SYSCALL_DEFINE6(splice, int, fd_in, loff_t __user *, off_in,
1389 int, fd_out, loff_t __user *, off_out,
1390 size_t, len, unsigned int, flags)
1391{
1392 struct fd in, out;
1393 long error;
1394
1395 if (unlikely(!len))
1396 return 0;
1397
1398 if (unlikely(flags & ~SPLICE_F_ALL))
1399 return -EINVAL;
1400
1401 error = -EBADF;
1402 in = fdget(fd_in);
1403 if (in.file) {
1404 if (in.file->f_mode & FMODE_READ) {
1405 out = fdget(fd_out);
1406 if (out.file) {
1407 if (out.file->f_mode & FMODE_WRITE)
1408 error = do_splice(in.file, off_in,
1409 out.file, off_out,
1410 len, flags);
1411 fdput(out);
1412 }
1413 }
1414 fdput(in);
1415 }
1416 return error;
1417}
1418
1419/*
1420 * Make sure there's data to read. Wait for input if we can, otherwise
1421 * return an appropriate error.
1422 */
1423static int ipipe_prep(struct pipe_inode_info *pipe, unsigned int flags)
1424{
1425 int ret;
1426
1427 /*
1428 * Check ->nrbufs without the inode lock first. This function
1429 * is speculative anyways, so missing one is ok.
1430 */
1431 if (pipe->nrbufs)
1432 return 0;
1433
1434 ret = 0;
1435 pipe_lock(pipe);
1436
1437 while (!pipe->nrbufs) {
1438 if (signal_pending(current)) {
1439 ret = -ERESTARTSYS;
1440 break;
1441 }
1442 if (!pipe->writers)
1443 break;
1444 if (!pipe->waiting_writers) {
1445 if (flags & SPLICE_F_NONBLOCK) {
1446 ret = -EAGAIN;
1447 break;
1448 }
1449 }
1450 pipe_wait(pipe);
1451 }
1452
1453 pipe_unlock(pipe);
1454 return ret;
1455}
1456
1457/*
1458 * Make sure there's writeable room. Wait for room if we can, otherwise
1459 * return an appropriate error.
1460 */
1461static int opipe_prep(struct pipe_inode_info *pipe, unsigned int flags)
1462{
1463 int ret;
1464
1465 /*
1466 * Check ->nrbufs without the inode lock first. This function
1467 * is speculative anyways, so missing one is ok.
1468 */
1469 if (pipe->nrbufs < pipe->buffers)
1470 return 0;
1471
1472 ret = 0;
1473 pipe_lock(pipe);
1474
1475 while (pipe->nrbufs >= pipe->buffers) {
1476 if (!pipe->readers) {
1477 send_sig(SIGPIPE, current, 0);
1478 ret = -EPIPE;
1479 break;
1480 }
1481 if (flags & SPLICE_F_NONBLOCK) {
1482 ret = -EAGAIN;
1483 break;
1484 }
1485 if (signal_pending(current)) {
1486 ret = -ERESTARTSYS;
1487 break;
1488 }
1489 pipe->waiting_writers++;
1490 pipe_wait(pipe);
1491 pipe->waiting_writers--;
1492 }
1493
1494 pipe_unlock(pipe);
1495 return ret;
1496}
1497
1498/*
1499 * Splice contents of ipipe to opipe.
1500 */
1501static int splice_pipe_to_pipe(struct pipe_inode_info *ipipe,
1502 struct pipe_inode_info *opipe,
1503 size_t len, unsigned int flags)
1504{
1505 struct pipe_buffer *ibuf, *obuf;
1506 int ret = 0, nbuf;
1507 bool input_wakeup = false;
1508
1509
1510retry:
1511 ret = ipipe_prep(ipipe, flags);
1512 if (ret)
1513 return ret;
1514
1515 ret = opipe_prep(opipe, flags);
1516 if (ret)
1517 return ret;
1518
1519 /*
1520 * Potential ABBA deadlock, work around it by ordering lock
1521 * grabbing by pipe info address. Otherwise two different processes
1522 * could deadlock (one doing tee from A -> B, the other from B -> A).
1523 */
1524 pipe_double_lock(ipipe, opipe);
1525
1526 do {
1527 if (!opipe->readers) {
1528 send_sig(SIGPIPE, current, 0);
1529 if (!ret)
1530 ret = -EPIPE;
1531 break;
1532 }
1533
1534 if (!ipipe->nrbufs && !ipipe->writers)
1535 break;
1536
1537 /*
1538 * Cannot make any progress, because either the input
1539 * pipe is empty or the output pipe is full.
1540 */
1541 if (!ipipe->nrbufs || opipe->nrbufs >= opipe->buffers) {
1542 /* Already processed some buffers, break */
1543 if (ret)
1544 break;
1545
1546 if (flags & SPLICE_F_NONBLOCK) {
1547 ret = -EAGAIN;
1548 break;
1549 }
1550
1551 /*
1552 * We raced with another reader/writer and haven't
1553 * managed to process any buffers. A zero return
1554 * value means EOF, so retry instead.
1555 */
1556 pipe_unlock(ipipe);
1557 pipe_unlock(opipe);
1558 goto retry;
1559 }
1560
1561 ibuf = ipipe->bufs + ipipe->curbuf;
1562 nbuf = (opipe->curbuf + opipe->nrbufs) & (opipe->buffers - 1);
1563 obuf = opipe->bufs + nbuf;
1564
1565 if (len >= ibuf->len) {
1566 /*
1567 * Simply move the whole buffer from ipipe to opipe
1568 */
1569 *obuf = *ibuf;
1570 ibuf->ops = NULL;
1571 opipe->nrbufs++;
1572 ipipe->curbuf = (ipipe->curbuf + 1) & (ipipe->buffers - 1);
1573 ipipe->nrbufs--;
1574 input_wakeup = true;
1575 } else {
1576 /*
1577 * Get a reference to this pipe buffer,
1578 * so we can copy the contents over.
1579 */
1580 pipe_buf_get(ipipe, ibuf);
1581 *obuf = *ibuf;
1582
1583 /*
1584 * Don't inherit the gift flag, we need to
1585 * prevent multiple steals of this page.
1586 */
1587 obuf->flags &= ~PIPE_BUF_FLAG_GIFT;
1588
1589 obuf->len = len;
1590 opipe->nrbufs++;
1591 ibuf->offset += obuf->len;
1592 ibuf->len -= obuf->len;
1593 }
1594 ret += obuf->len;
1595 len -= obuf->len;
1596 } while (len);
1597
1598 pipe_unlock(ipipe);
1599 pipe_unlock(opipe);
1600
1601 /*
1602 * If we put data in the output pipe, wakeup any potential readers.
1603 */
1604 if (ret > 0)
1605 wakeup_pipe_readers(opipe);
1606
1607 if (input_wakeup)
1608 wakeup_pipe_writers(ipipe);
1609
1610 return ret;
1611}
1612
1613/*
1614 * Link contents of ipipe to opipe.
1615 */
1616static int link_pipe(struct pipe_inode_info *ipipe,
1617 struct pipe_inode_info *opipe,
1618 size_t len, unsigned int flags)
1619{
1620 struct pipe_buffer *ibuf, *obuf;
1621 int ret = 0, i = 0, nbuf;
1622
1623 /*
1624 * Potential ABBA deadlock, work around it by ordering lock
1625 * grabbing by pipe info address. Otherwise two different processes
1626 * could deadlock (one doing tee from A -> B, the other from B -> A).
1627 */
1628 pipe_double_lock(ipipe, opipe);
1629
1630 do {
1631 if (!opipe->readers) {
1632 send_sig(SIGPIPE, current, 0);
1633 if (!ret)
1634 ret = -EPIPE;
1635 break;
1636 }
1637
1638 /*
1639 * If we have iterated all input buffers or ran out of
1640 * output room, break.
1641 */
1642 if (i >= ipipe->nrbufs || opipe->nrbufs >= opipe->buffers)
1643 break;
1644
1645 ibuf = ipipe->bufs + ((ipipe->curbuf + i) & (ipipe->buffers-1));
1646 nbuf = (opipe->curbuf + opipe->nrbufs) & (opipe->buffers - 1);
1647
1648 /*
1649 * Get a reference to this pipe buffer,
1650 * so we can copy the contents over.
1651 */
1652 pipe_buf_get(ipipe, ibuf);
1653
1654 obuf = opipe->bufs + nbuf;
1655 *obuf = *ibuf;
1656
1657 /*
1658 * Don't inherit the gift flag, we need to
1659 * prevent multiple steals of this page.
1660 */
1661 obuf->flags &= ~PIPE_BUF_FLAG_GIFT;
1662
1663 if (obuf->len > len)
1664 obuf->len = len;
1665
1666 opipe->nrbufs++;
1667 ret += obuf->len;
1668 len -= obuf->len;
1669 i++;
1670 } while (len);
1671
1672 /*
1673 * return EAGAIN if we have the potential of some data in the
1674 * future, otherwise just return 0
1675 */
1676 if (!ret && ipipe->waiting_writers && (flags & SPLICE_F_NONBLOCK))
1677 ret = -EAGAIN;
1678
1679 pipe_unlock(ipipe);
1680 pipe_unlock(opipe);
1681
1682 /*
1683 * If we put data in the output pipe, wakeup any potential readers.
1684 */
1685 if (ret > 0)
1686 wakeup_pipe_readers(opipe);
1687
1688 return ret;
1689}
1690
1691/*
1692 * This is a tee(1) implementation that works on pipes. It doesn't copy
1693 * any data, it simply references the 'in' pages on the 'out' pipe.
1694 * The 'flags' used are the SPLICE_F_* variants, currently the only
1695 * applicable one is SPLICE_F_NONBLOCK.
1696 */
1697static long do_tee(struct file *in, struct file *out, size_t len,
1698 unsigned int flags)
1699{
1700 struct pipe_inode_info *ipipe = get_pipe_info(in);
1701 struct pipe_inode_info *opipe = get_pipe_info(out);
1702 int ret = -EINVAL;
1703
1704 /*
1705 * Duplicate the contents of ipipe to opipe without actually
1706 * copying the data.
1707 */
1708 if (ipipe && opipe && ipipe != opipe) {
1709 /*
1710 * Keep going, unless we encounter an error. The ipipe/opipe
1711 * ordering doesn't really matter.
1712 */
1713 ret = ipipe_prep(ipipe, flags);
1714 if (!ret) {
1715 ret = opipe_prep(opipe, flags);
1716 if (!ret)
1717 ret = link_pipe(ipipe, opipe, len, flags);
1718 }
1719 }
1720
1721 return ret;
1722}
1723
1724SYSCALL_DEFINE4(tee, int, fdin, int, fdout, size_t, len, unsigned int, flags)
1725{
1726 struct fd in;
1727 int error;
1728
1729 if (unlikely(flags & ~SPLICE_F_ALL))
1730 return -EINVAL;
1731
1732 if (unlikely(!len))
1733 return 0;
1734
1735 error = -EBADF;
1736 in = fdget(fdin);
1737 if (in.file) {
1738 if (in.file->f_mode & FMODE_READ) {
1739 struct fd out = fdget(fdout);
1740 if (out.file) {
1741 if (out.file->f_mode & FMODE_WRITE)
1742 error = do_tee(in.file, out.file,
1743 len, flags);
1744 fdput(out);
1745 }
1746 }
1747 fdput(in);
1748 }
1749
1750 return error;
1751}
1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * "splice": joining two ropes together by interweaving their strands.
4 *
5 * This is the "extended pipe" functionality, where a pipe is used as
6 * an arbitrary in-memory buffer. Think of a pipe as a small kernel
7 * buffer that you can use to transfer data from one end to the other.
8 *
9 * The traditional unix read/write is extended with a "splice()" operation
10 * that transfers data buffers to or from a pipe buffer.
11 *
12 * Named by Larry McVoy, original implementation from Linus, extended by
13 * Jens to support splicing to files, network, direct splicing, etc and
14 * fixing lots of bugs.
15 *
16 * Copyright (C) 2005-2006 Jens Axboe <axboe@kernel.dk>
17 * Copyright (C) 2005-2006 Linus Torvalds <torvalds@osdl.org>
18 * Copyright (C) 2006 Ingo Molnar <mingo@elte.hu>
19 *
20 */
21#include <linux/bvec.h>
22#include <linux/fs.h>
23#include <linux/file.h>
24#include <linux/pagemap.h>
25#include <linux/splice.h>
26#include <linux/memcontrol.h>
27#include <linux/mm_inline.h>
28#include <linux/swap.h>
29#include <linux/writeback.h>
30#include <linux/export.h>
31#include <linux/syscalls.h>
32#include <linux/uio.h>
33#include <linux/security.h>
34#include <linux/gfp.h>
35#include <linux/socket.h>
36#include <linux/sched/signal.h>
37
38#include "internal.h"
39
40/*
41 * Attempt to steal a page from a pipe buffer. This should perhaps go into
42 * a vm helper function, it's already simplified quite a bit by the
43 * addition of remove_mapping(). If success is returned, the caller may
44 * attempt to reuse this page for another destination.
45 */
46static bool page_cache_pipe_buf_try_steal(struct pipe_inode_info *pipe,
47 struct pipe_buffer *buf)
48{
49 struct page *page = buf->page;
50 struct address_space *mapping;
51
52 lock_page(page);
53
54 mapping = page_mapping(page);
55 if (mapping) {
56 WARN_ON(!PageUptodate(page));
57
58 /*
59 * At least for ext2 with nobh option, we need to wait on
60 * writeback completing on this page, since we'll remove it
61 * from the pagecache. Otherwise truncate wont wait on the
62 * page, allowing the disk blocks to be reused by someone else
63 * before we actually wrote our data to them. fs corruption
64 * ensues.
65 */
66 wait_on_page_writeback(page);
67
68 if (page_has_private(page) &&
69 !try_to_release_page(page, GFP_KERNEL))
70 goto out_unlock;
71
72 /*
73 * If we succeeded in removing the mapping, set LRU flag
74 * and return good.
75 */
76 if (remove_mapping(mapping, page)) {
77 buf->flags |= PIPE_BUF_FLAG_LRU;
78 return true;
79 }
80 }
81
82 /*
83 * Raced with truncate or failed to remove page from current
84 * address space, unlock and return failure.
85 */
86out_unlock:
87 unlock_page(page);
88 return false;
89}
90
91static void page_cache_pipe_buf_release(struct pipe_inode_info *pipe,
92 struct pipe_buffer *buf)
93{
94 put_page(buf->page);
95 buf->flags &= ~PIPE_BUF_FLAG_LRU;
96}
97
98/*
99 * Check whether the contents of buf is OK to access. Since the content
100 * is a page cache page, IO may be in flight.
101 */
102static int page_cache_pipe_buf_confirm(struct pipe_inode_info *pipe,
103 struct pipe_buffer *buf)
104{
105 struct page *page = buf->page;
106 int err;
107
108 if (!PageUptodate(page)) {
109 lock_page(page);
110
111 /*
112 * Page got truncated/unhashed. This will cause a 0-byte
113 * splice, if this is the first page.
114 */
115 if (!page->mapping) {
116 err = -ENODATA;
117 goto error;
118 }
119
120 /*
121 * Uh oh, read-error from disk.
122 */
123 if (!PageUptodate(page)) {
124 err = -EIO;
125 goto error;
126 }
127
128 /*
129 * Page is ok afterall, we are done.
130 */
131 unlock_page(page);
132 }
133
134 return 0;
135error:
136 unlock_page(page);
137 return err;
138}
139
140const struct pipe_buf_operations page_cache_pipe_buf_ops = {
141 .confirm = page_cache_pipe_buf_confirm,
142 .release = page_cache_pipe_buf_release,
143 .try_steal = page_cache_pipe_buf_try_steal,
144 .get = generic_pipe_buf_get,
145};
146
147static bool user_page_pipe_buf_try_steal(struct pipe_inode_info *pipe,
148 struct pipe_buffer *buf)
149{
150 if (!(buf->flags & PIPE_BUF_FLAG_GIFT))
151 return false;
152
153 buf->flags |= PIPE_BUF_FLAG_LRU;
154 return generic_pipe_buf_try_steal(pipe, buf);
155}
156
157static const struct pipe_buf_operations user_page_pipe_buf_ops = {
158 .release = page_cache_pipe_buf_release,
159 .try_steal = user_page_pipe_buf_try_steal,
160 .get = generic_pipe_buf_get,
161};
162
163static void wakeup_pipe_readers(struct pipe_inode_info *pipe)
164{
165 smp_mb();
166 if (waitqueue_active(&pipe->rd_wait))
167 wake_up_interruptible(&pipe->rd_wait);
168 kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
169}
170
171/**
172 * splice_to_pipe - fill passed data into a pipe
173 * @pipe: pipe to fill
174 * @spd: data to fill
175 *
176 * Description:
177 * @spd contains a map of pages and len/offset tuples, along with
178 * the struct pipe_buf_operations associated with these pages. This
179 * function will link that data to the pipe.
180 *
181 */
182ssize_t splice_to_pipe(struct pipe_inode_info *pipe,
183 struct splice_pipe_desc *spd)
184{
185 unsigned int spd_pages = spd->nr_pages;
186 unsigned int tail = pipe->tail;
187 unsigned int head = pipe->head;
188 unsigned int mask = pipe->ring_size - 1;
189 int ret = 0, page_nr = 0;
190
191 if (!spd_pages)
192 return 0;
193
194 if (unlikely(!pipe->readers)) {
195 send_sig(SIGPIPE, current, 0);
196 ret = -EPIPE;
197 goto out;
198 }
199
200 while (!pipe_full(head, tail, pipe->max_usage)) {
201 struct pipe_buffer *buf = &pipe->bufs[head & mask];
202
203 buf->page = spd->pages[page_nr];
204 buf->offset = spd->partial[page_nr].offset;
205 buf->len = spd->partial[page_nr].len;
206 buf->private = spd->partial[page_nr].private;
207 buf->ops = spd->ops;
208 buf->flags = 0;
209
210 head++;
211 pipe->head = head;
212 page_nr++;
213 ret += buf->len;
214
215 if (!--spd->nr_pages)
216 break;
217 }
218
219 if (!ret)
220 ret = -EAGAIN;
221
222out:
223 while (page_nr < spd_pages)
224 spd->spd_release(spd, page_nr++);
225
226 return ret;
227}
228EXPORT_SYMBOL_GPL(splice_to_pipe);
229
230ssize_t add_to_pipe(struct pipe_inode_info *pipe, struct pipe_buffer *buf)
231{
232 unsigned int head = pipe->head;
233 unsigned int tail = pipe->tail;
234 unsigned int mask = pipe->ring_size - 1;
235 int ret;
236
237 if (unlikely(!pipe->readers)) {
238 send_sig(SIGPIPE, current, 0);
239 ret = -EPIPE;
240 } else if (pipe_full(head, tail, pipe->max_usage)) {
241 ret = -EAGAIN;
242 } else {
243 pipe->bufs[head & mask] = *buf;
244 pipe->head = head + 1;
245 return buf->len;
246 }
247 pipe_buf_release(pipe, buf);
248 return ret;
249}
250EXPORT_SYMBOL(add_to_pipe);
251
252/*
253 * Check if we need to grow the arrays holding pages and partial page
254 * descriptions.
255 */
256int splice_grow_spd(const struct pipe_inode_info *pipe, struct splice_pipe_desc *spd)
257{
258 unsigned int max_usage = READ_ONCE(pipe->max_usage);
259
260 spd->nr_pages_max = max_usage;
261 if (max_usage <= PIPE_DEF_BUFFERS)
262 return 0;
263
264 spd->pages = kmalloc_array(max_usage, sizeof(struct page *), GFP_KERNEL);
265 spd->partial = kmalloc_array(max_usage, sizeof(struct partial_page),
266 GFP_KERNEL);
267
268 if (spd->pages && spd->partial)
269 return 0;
270
271 kfree(spd->pages);
272 kfree(spd->partial);
273 return -ENOMEM;
274}
275
276void splice_shrink_spd(struct splice_pipe_desc *spd)
277{
278 if (spd->nr_pages_max <= PIPE_DEF_BUFFERS)
279 return;
280
281 kfree(spd->pages);
282 kfree(spd->partial);
283}
284
285/**
286 * generic_file_splice_read - splice data from file to a pipe
287 * @in: file to splice from
288 * @ppos: position in @in
289 * @pipe: pipe to splice to
290 * @len: number of bytes to splice
291 * @flags: splice modifier flags
292 *
293 * Description:
294 * Will read pages from given file and fill them into a pipe. Can be
295 * used as long as it has more or less sane ->read_iter().
296 *
297 */
298ssize_t generic_file_splice_read(struct file *in, loff_t *ppos,
299 struct pipe_inode_info *pipe, size_t len,
300 unsigned int flags)
301{
302 struct iov_iter to;
303 struct kiocb kiocb;
304 unsigned int i_head;
305 int ret;
306
307 iov_iter_pipe(&to, READ, pipe, len);
308 i_head = to.head;
309 init_sync_kiocb(&kiocb, in);
310 kiocb.ki_pos = *ppos;
311 ret = call_read_iter(in, &kiocb, &to);
312 if (ret > 0) {
313 *ppos = kiocb.ki_pos;
314 file_accessed(in);
315 } else if (ret < 0) {
316 to.head = i_head;
317 to.iov_offset = 0;
318 iov_iter_advance(&to, 0); /* to free what was emitted */
319 /*
320 * callers of ->splice_read() expect -EAGAIN on
321 * "can't put anything in there", rather than -EFAULT.
322 */
323 if (ret == -EFAULT)
324 ret = -EAGAIN;
325 }
326
327 return ret;
328}
329EXPORT_SYMBOL(generic_file_splice_read);
330
331const struct pipe_buf_operations default_pipe_buf_ops = {
332 .release = generic_pipe_buf_release,
333 .try_steal = generic_pipe_buf_try_steal,
334 .get = generic_pipe_buf_get,
335};
336
337/* Pipe buffer operations for a socket and similar. */
338const struct pipe_buf_operations nosteal_pipe_buf_ops = {
339 .release = generic_pipe_buf_release,
340 .get = generic_pipe_buf_get,
341};
342EXPORT_SYMBOL(nosteal_pipe_buf_ops);
343
344/*
345 * Send 'sd->len' bytes to socket from 'sd->file' at position 'sd->pos'
346 * using sendpage(). Return the number of bytes sent.
347 */
348static int pipe_to_sendpage(struct pipe_inode_info *pipe,
349 struct pipe_buffer *buf, struct splice_desc *sd)
350{
351 struct file *file = sd->u.file;
352 loff_t pos = sd->pos;
353 int more;
354
355 if (!likely(file->f_op->sendpage))
356 return -EINVAL;
357
358 more = (sd->flags & SPLICE_F_MORE) ? MSG_MORE : 0;
359
360 if (sd->len < sd->total_len &&
361 pipe_occupancy(pipe->head, pipe->tail) > 1)
362 more |= MSG_SENDPAGE_NOTLAST;
363
364 return file->f_op->sendpage(file, buf->page, buf->offset,
365 sd->len, &pos, more);
366}
367
368static void wakeup_pipe_writers(struct pipe_inode_info *pipe)
369{
370 smp_mb();
371 if (waitqueue_active(&pipe->wr_wait))
372 wake_up_interruptible(&pipe->wr_wait);
373 kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT);
374}
375
376/**
377 * splice_from_pipe_feed - feed available data from a pipe to a file
378 * @pipe: pipe to splice from
379 * @sd: information to @actor
380 * @actor: handler that splices the data
381 *
382 * Description:
383 * This function loops over the pipe and calls @actor to do the
384 * actual moving of a single struct pipe_buffer to the desired
385 * destination. It returns when there's no more buffers left in
386 * the pipe or if the requested number of bytes (@sd->total_len)
387 * have been copied. It returns a positive number (one) if the
388 * pipe needs to be filled with more data, zero if the required
389 * number of bytes have been copied and -errno on error.
390 *
391 * This, together with splice_from_pipe_{begin,end,next}, may be
392 * used to implement the functionality of __splice_from_pipe() when
393 * locking is required around copying the pipe buffers to the
394 * destination.
395 */
396static int splice_from_pipe_feed(struct pipe_inode_info *pipe, struct splice_desc *sd,
397 splice_actor *actor)
398{
399 unsigned int head = pipe->head;
400 unsigned int tail = pipe->tail;
401 unsigned int mask = pipe->ring_size - 1;
402 int ret;
403
404 while (!pipe_empty(head, tail)) {
405 struct pipe_buffer *buf = &pipe->bufs[tail & mask];
406
407 sd->len = buf->len;
408 if (sd->len > sd->total_len)
409 sd->len = sd->total_len;
410
411 ret = pipe_buf_confirm(pipe, buf);
412 if (unlikely(ret)) {
413 if (ret == -ENODATA)
414 ret = 0;
415 return ret;
416 }
417
418 ret = actor(pipe, buf, sd);
419 if (ret <= 0)
420 return ret;
421
422 buf->offset += ret;
423 buf->len -= ret;
424
425 sd->num_spliced += ret;
426 sd->len -= ret;
427 sd->pos += ret;
428 sd->total_len -= ret;
429
430 if (!buf->len) {
431 pipe_buf_release(pipe, buf);
432 tail++;
433 pipe->tail = tail;
434 if (pipe->files)
435 sd->need_wakeup = true;
436 }
437
438 if (!sd->total_len)
439 return 0;
440 }
441
442 return 1;
443}
444
445/* We know we have a pipe buffer, but maybe it's empty? */
446static inline bool eat_empty_buffer(struct pipe_inode_info *pipe)
447{
448 unsigned int tail = pipe->tail;
449 unsigned int mask = pipe->ring_size - 1;
450 struct pipe_buffer *buf = &pipe->bufs[tail & mask];
451
452 if (unlikely(!buf->len)) {
453 pipe_buf_release(pipe, buf);
454 pipe->tail = tail+1;
455 return true;
456 }
457
458 return false;
459}
460
461/**
462 * splice_from_pipe_next - wait for some data to splice from
463 * @pipe: pipe to splice from
464 * @sd: information about the splice operation
465 *
466 * Description:
467 * This function will wait for some data and return a positive
468 * value (one) if pipe buffers are available. It will return zero
469 * or -errno if no more data needs to be spliced.
470 */
471static int splice_from_pipe_next(struct pipe_inode_info *pipe, struct splice_desc *sd)
472{
473 /*
474 * Check for signal early to make process killable when there are
475 * always buffers available
476 */
477 if (signal_pending(current))
478 return -ERESTARTSYS;
479
480repeat:
481 while (pipe_empty(pipe->head, pipe->tail)) {
482 if (!pipe->writers)
483 return 0;
484
485 if (sd->num_spliced)
486 return 0;
487
488 if (sd->flags & SPLICE_F_NONBLOCK)
489 return -EAGAIN;
490
491 if (signal_pending(current))
492 return -ERESTARTSYS;
493
494 if (sd->need_wakeup) {
495 wakeup_pipe_writers(pipe);
496 sd->need_wakeup = false;
497 }
498
499 pipe_wait_readable(pipe);
500 }
501
502 if (eat_empty_buffer(pipe))
503 goto repeat;
504
505 return 1;
506}
507
508/**
509 * splice_from_pipe_begin - start splicing from pipe
510 * @sd: information about the splice operation
511 *
512 * Description:
513 * This function should be called before a loop containing
514 * splice_from_pipe_next() and splice_from_pipe_feed() to
515 * initialize the necessary fields of @sd.
516 */
517static void splice_from_pipe_begin(struct splice_desc *sd)
518{
519 sd->num_spliced = 0;
520 sd->need_wakeup = false;
521}
522
523/**
524 * splice_from_pipe_end - finish splicing from pipe
525 * @pipe: pipe to splice from
526 * @sd: information about the splice operation
527 *
528 * Description:
529 * This function will wake up pipe writers if necessary. It should
530 * be called after a loop containing splice_from_pipe_next() and
531 * splice_from_pipe_feed().
532 */
533static void splice_from_pipe_end(struct pipe_inode_info *pipe, struct splice_desc *sd)
534{
535 if (sd->need_wakeup)
536 wakeup_pipe_writers(pipe);
537}
538
539/**
540 * __splice_from_pipe - splice data from a pipe to given actor
541 * @pipe: pipe to splice from
542 * @sd: information to @actor
543 * @actor: handler that splices the data
544 *
545 * Description:
546 * This function does little more than loop over the pipe and call
547 * @actor to do the actual moving of a single struct pipe_buffer to
548 * the desired destination. See pipe_to_file, pipe_to_sendpage, or
549 * pipe_to_user.
550 *
551 */
552ssize_t __splice_from_pipe(struct pipe_inode_info *pipe, struct splice_desc *sd,
553 splice_actor *actor)
554{
555 int ret;
556
557 splice_from_pipe_begin(sd);
558 do {
559 cond_resched();
560 ret = splice_from_pipe_next(pipe, sd);
561 if (ret > 0)
562 ret = splice_from_pipe_feed(pipe, sd, actor);
563 } while (ret > 0);
564 splice_from_pipe_end(pipe, sd);
565
566 return sd->num_spliced ? sd->num_spliced : ret;
567}
568EXPORT_SYMBOL(__splice_from_pipe);
569
570/**
571 * splice_from_pipe - splice data from a pipe to a file
572 * @pipe: pipe to splice from
573 * @out: file to splice to
574 * @ppos: position in @out
575 * @len: how many bytes to splice
576 * @flags: splice modifier flags
577 * @actor: handler that splices the data
578 *
579 * Description:
580 * See __splice_from_pipe. This function locks the pipe inode,
581 * otherwise it's identical to __splice_from_pipe().
582 *
583 */
584ssize_t splice_from_pipe(struct pipe_inode_info *pipe, struct file *out,
585 loff_t *ppos, size_t len, unsigned int flags,
586 splice_actor *actor)
587{
588 ssize_t ret;
589 struct splice_desc sd = {
590 .total_len = len,
591 .flags = flags,
592 .pos = *ppos,
593 .u.file = out,
594 };
595
596 pipe_lock(pipe);
597 ret = __splice_from_pipe(pipe, &sd, actor);
598 pipe_unlock(pipe);
599
600 return ret;
601}
602
603/**
604 * iter_file_splice_write - splice data from a pipe to a file
605 * @pipe: pipe info
606 * @out: file to write to
607 * @ppos: position in @out
608 * @len: number of bytes to splice
609 * @flags: splice modifier flags
610 *
611 * Description:
612 * Will either move or copy pages (determined by @flags options) from
613 * the given pipe inode to the given file.
614 * This one is ->write_iter-based.
615 *
616 */
617ssize_t
618iter_file_splice_write(struct pipe_inode_info *pipe, struct file *out,
619 loff_t *ppos, size_t len, unsigned int flags)
620{
621 struct splice_desc sd = {
622 .total_len = len,
623 .flags = flags,
624 .pos = *ppos,
625 .u.file = out,
626 };
627 int nbufs = pipe->max_usage;
628 struct bio_vec *array = kcalloc(nbufs, sizeof(struct bio_vec),
629 GFP_KERNEL);
630 ssize_t ret;
631
632 if (unlikely(!array))
633 return -ENOMEM;
634
635 pipe_lock(pipe);
636
637 splice_from_pipe_begin(&sd);
638 while (sd.total_len) {
639 struct iov_iter from;
640 unsigned int head, tail, mask;
641 size_t left;
642 int n;
643
644 ret = splice_from_pipe_next(pipe, &sd);
645 if (ret <= 0)
646 break;
647
648 if (unlikely(nbufs < pipe->max_usage)) {
649 kfree(array);
650 nbufs = pipe->max_usage;
651 array = kcalloc(nbufs, sizeof(struct bio_vec),
652 GFP_KERNEL);
653 if (!array) {
654 ret = -ENOMEM;
655 break;
656 }
657 }
658
659 head = pipe->head;
660 tail = pipe->tail;
661 mask = pipe->ring_size - 1;
662
663 /* build the vector */
664 left = sd.total_len;
665 for (n = 0; !pipe_empty(head, tail) && left && n < nbufs; tail++) {
666 struct pipe_buffer *buf = &pipe->bufs[tail & mask];
667 size_t this_len = buf->len;
668
669 /* zero-length bvecs are not supported, skip them */
670 if (!this_len)
671 continue;
672 this_len = min(this_len, left);
673
674 ret = pipe_buf_confirm(pipe, buf);
675 if (unlikely(ret)) {
676 if (ret == -ENODATA)
677 ret = 0;
678 goto done;
679 }
680
681 array[n].bv_page = buf->page;
682 array[n].bv_len = this_len;
683 array[n].bv_offset = buf->offset;
684 left -= this_len;
685 n++;
686 }
687
688 iov_iter_bvec(&from, WRITE, array, n, sd.total_len - left);
689 ret = vfs_iter_write(out, &from, &sd.pos, 0);
690 if (ret <= 0)
691 break;
692
693 sd.num_spliced += ret;
694 sd.total_len -= ret;
695 *ppos = sd.pos;
696
697 /* dismiss the fully eaten buffers, adjust the partial one */
698 tail = pipe->tail;
699 while (ret) {
700 struct pipe_buffer *buf = &pipe->bufs[tail & mask];
701 if (ret >= buf->len) {
702 ret -= buf->len;
703 buf->len = 0;
704 pipe_buf_release(pipe, buf);
705 tail++;
706 pipe->tail = tail;
707 if (pipe->files)
708 sd.need_wakeup = true;
709 } else {
710 buf->offset += ret;
711 buf->len -= ret;
712 ret = 0;
713 }
714 }
715 }
716done:
717 kfree(array);
718 splice_from_pipe_end(pipe, &sd);
719
720 pipe_unlock(pipe);
721
722 if (sd.num_spliced)
723 ret = sd.num_spliced;
724
725 return ret;
726}
727
728EXPORT_SYMBOL(iter_file_splice_write);
729
730/**
731 * generic_splice_sendpage - splice data from a pipe to a socket
732 * @pipe: pipe to splice from
733 * @out: socket to write to
734 * @ppos: position in @out
735 * @len: number of bytes to splice
736 * @flags: splice modifier flags
737 *
738 * Description:
739 * Will send @len bytes from the pipe to a network socket. No data copying
740 * is involved.
741 *
742 */
743ssize_t generic_splice_sendpage(struct pipe_inode_info *pipe, struct file *out,
744 loff_t *ppos, size_t len, unsigned int flags)
745{
746 return splice_from_pipe(pipe, out, ppos, len, flags, pipe_to_sendpage);
747}
748
749EXPORT_SYMBOL(generic_splice_sendpage);
750
751static int warn_unsupported(struct file *file, const char *op)
752{
753 pr_debug_ratelimited(
754 "splice %s not supported for file %pD4 (pid: %d comm: %.20s)\n",
755 op, file, current->pid, current->comm);
756 return -EINVAL;
757}
758
759/*
760 * Attempt to initiate a splice from pipe to file.
761 */
762static long do_splice_from(struct pipe_inode_info *pipe, struct file *out,
763 loff_t *ppos, size_t len, unsigned int flags)
764{
765 if (unlikely(!out->f_op->splice_write))
766 return warn_unsupported(out, "write");
767 return out->f_op->splice_write(pipe, out, ppos, len, flags);
768}
769
770/*
771 * Attempt to initiate a splice from a file to a pipe.
772 */
773static long do_splice_to(struct file *in, loff_t *ppos,
774 struct pipe_inode_info *pipe, size_t len,
775 unsigned int flags)
776{
777 unsigned int p_space;
778 int ret;
779
780 if (unlikely(!(in->f_mode & FMODE_READ)))
781 return -EBADF;
782
783 /* Don't try to read more the pipe has space for. */
784 p_space = pipe->max_usage - pipe_occupancy(pipe->head, pipe->tail);
785 len = min_t(size_t, len, p_space << PAGE_SHIFT);
786
787 ret = rw_verify_area(READ, in, ppos, len);
788 if (unlikely(ret < 0))
789 return ret;
790
791 if (unlikely(len > MAX_RW_COUNT))
792 len = MAX_RW_COUNT;
793
794 if (unlikely(!in->f_op->splice_read))
795 return warn_unsupported(in, "read");
796 return in->f_op->splice_read(in, ppos, pipe, len, flags);
797}
798
799/**
800 * splice_direct_to_actor - splices data directly between two non-pipes
801 * @in: file to splice from
802 * @sd: actor information on where to splice to
803 * @actor: handles the data splicing
804 *
805 * Description:
806 * This is a special case helper to splice directly between two
807 * points, without requiring an explicit pipe. Internally an allocated
808 * pipe is cached in the process, and reused during the lifetime of
809 * that process.
810 *
811 */
812ssize_t splice_direct_to_actor(struct file *in, struct splice_desc *sd,
813 splice_direct_actor *actor)
814{
815 struct pipe_inode_info *pipe;
816 long ret, bytes;
817 umode_t i_mode;
818 size_t len;
819 int i, flags, more;
820
821 /*
822 * We require the input being a regular file, as we don't want to
823 * randomly drop data for eg socket -> socket splicing. Use the
824 * piped splicing for that!
825 */
826 i_mode = file_inode(in)->i_mode;
827 if (unlikely(!S_ISREG(i_mode) && !S_ISBLK(i_mode)))
828 return -EINVAL;
829
830 /*
831 * neither in nor out is a pipe, setup an internal pipe attached to
832 * 'out' and transfer the wanted data from 'in' to 'out' through that
833 */
834 pipe = current->splice_pipe;
835 if (unlikely(!pipe)) {
836 pipe = alloc_pipe_info();
837 if (!pipe)
838 return -ENOMEM;
839
840 /*
841 * We don't have an immediate reader, but we'll read the stuff
842 * out of the pipe right after the splice_to_pipe(). So set
843 * PIPE_READERS appropriately.
844 */
845 pipe->readers = 1;
846
847 current->splice_pipe = pipe;
848 }
849
850 /*
851 * Do the splice.
852 */
853 ret = 0;
854 bytes = 0;
855 len = sd->total_len;
856 flags = sd->flags;
857
858 /*
859 * Don't block on output, we have to drain the direct pipe.
860 */
861 sd->flags &= ~SPLICE_F_NONBLOCK;
862 more = sd->flags & SPLICE_F_MORE;
863
864 WARN_ON_ONCE(!pipe_empty(pipe->head, pipe->tail));
865
866 while (len) {
867 size_t read_len;
868 loff_t pos = sd->pos, prev_pos = pos;
869
870 ret = do_splice_to(in, &pos, pipe, len, flags);
871 if (unlikely(ret <= 0))
872 goto out_release;
873
874 read_len = ret;
875 sd->total_len = read_len;
876
877 /*
878 * If more data is pending, set SPLICE_F_MORE
879 * If this is the last data and SPLICE_F_MORE was not set
880 * initially, clears it.
881 */
882 if (read_len < len)
883 sd->flags |= SPLICE_F_MORE;
884 else if (!more)
885 sd->flags &= ~SPLICE_F_MORE;
886 /*
887 * NOTE: nonblocking mode only applies to the input. We
888 * must not do the output in nonblocking mode as then we
889 * could get stuck data in the internal pipe:
890 */
891 ret = actor(pipe, sd);
892 if (unlikely(ret <= 0)) {
893 sd->pos = prev_pos;
894 goto out_release;
895 }
896
897 bytes += ret;
898 len -= ret;
899 sd->pos = pos;
900
901 if (ret < read_len) {
902 sd->pos = prev_pos + ret;
903 goto out_release;
904 }
905 }
906
907done:
908 pipe->tail = pipe->head = 0;
909 file_accessed(in);
910 return bytes;
911
912out_release:
913 /*
914 * If we did an incomplete transfer we must release
915 * the pipe buffers in question:
916 */
917 for (i = 0; i < pipe->ring_size; i++) {
918 struct pipe_buffer *buf = &pipe->bufs[i];
919
920 if (buf->ops)
921 pipe_buf_release(pipe, buf);
922 }
923
924 if (!bytes)
925 bytes = ret;
926
927 goto done;
928}
929EXPORT_SYMBOL(splice_direct_to_actor);
930
931static int direct_splice_actor(struct pipe_inode_info *pipe,
932 struct splice_desc *sd)
933{
934 struct file *file = sd->u.file;
935
936 return do_splice_from(pipe, file, sd->opos, sd->total_len,
937 sd->flags);
938}
939
940/**
941 * do_splice_direct - splices data directly between two files
942 * @in: file to splice from
943 * @ppos: input file offset
944 * @out: file to splice to
945 * @opos: output file offset
946 * @len: number of bytes to splice
947 * @flags: splice modifier flags
948 *
949 * Description:
950 * For use by do_sendfile(). splice can easily emulate sendfile, but
951 * doing it in the application would incur an extra system call
952 * (splice in + splice out, as compared to just sendfile()). So this helper
953 * can splice directly through a process-private pipe.
954 *
955 */
956long do_splice_direct(struct file *in, loff_t *ppos, struct file *out,
957 loff_t *opos, size_t len, unsigned int flags)
958{
959 struct splice_desc sd = {
960 .len = len,
961 .total_len = len,
962 .flags = flags,
963 .pos = *ppos,
964 .u.file = out,
965 .opos = opos,
966 };
967 long ret;
968
969 if (unlikely(!(out->f_mode & FMODE_WRITE)))
970 return -EBADF;
971
972 if (unlikely(out->f_flags & O_APPEND))
973 return -EINVAL;
974
975 ret = rw_verify_area(WRITE, out, opos, len);
976 if (unlikely(ret < 0))
977 return ret;
978
979 ret = splice_direct_to_actor(in, &sd, direct_splice_actor);
980 if (ret > 0)
981 *ppos = sd.pos;
982
983 return ret;
984}
985EXPORT_SYMBOL(do_splice_direct);
986
987static int wait_for_space(struct pipe_inode_info *pipe, unsigned flags)
988{
989 for (;;) {
990 if (unlikely(!pipe->readers)) {
991 send_sig(SIGPIPE, current, 0);
992 return -EPIPE;
993 }
994 if (!pipe_full(pipe->head, pipe->tail, pipe->max_usage))
995 return 0;
996 if (flags & SPLICE_F_NONBLOCK)
997 return -EAGAIN;
998 if (signal_pending(current))
999 return -ERESTARTSYS;
1000 pipe_wait_writable(pipe);
1001 }
1002}
1003
1004static int splice_pipe_to_pipe(struct pipe_inode_info *ipipe,
1005 struct pipe_inode_info *opipe,
1006 size_t len, unsigned int flags);
1007
1008long splice_file_to_pipe(struct file *in,
1009 struct pipe_inode_info *opipe,
1010 loff_t *offset,
1011 size_t len, unsigned int flags)
1012{
1013 long ret;
1014
1015 pipe_lock(opipe);
1016 ret = wait_for_space(opipe, flags);
1017 if (!ret)
1018 ret = do_splice_to(in, offset, opipe, len, flags);
1019 pipe_unlock(opipe);
1020 if (ret > 0)
1021 wakeup_pipe_readers(opipe);
1022 return ret;
1023}
1024
1025/*
1026 * Determine where to splice to/from.
1027 */
1028long do_splice(struct file *in, loff_t *off_in, struct file *out,
1029 loff_t *off_out, size_t len, unsigned int flags)
1030{
1031 struct pipe_inode_info *ipipe;
1032 struct pipe_inode_info *opipe;
1033 loff_t offset;
1034 long ret;
1035
1036 if (unlikely(!(in->f_mode & FMODE_READ) ||
1037 !(out->f_mode & FMODE_WRITE)))
1038 return -EBADF;
1039
1040 ipipe = get_pipe_info(in, true);
1041 opipe = get_pipe_info(out, true);
1042
1043 if (ipipe && opipe) {
1044 if (off_in || off_out)
1045 return -ESPIPE;
1046
1047 /* Splicing to self would be fun, but... */
1048 if (ipipe == opipe)
1049 return -EINVAL;
1050
1051 if ((in->f_flags | out->f_flags) & O_NONBLOCK)
1052 flags |= SPLICE_F_NONBLOCK;
1053
1054 return splice_pipe_to_pipe(ipipe, opipe, len, flags);
1055 }
1056
1057 if (ipipe) {
1058 if (off_in)
1059 return -ESPIPE;
1060 if (off_out) {
1061 if (!(out->f_mode & FMODE_PWRITE))
1062 return -EINVAL;
1063 offset = *off_out;
1064 } else {
1065 offset = out->f_pos;
1066 }
1067
1068 if (unlikely(out->f_flags & O_APPEND))
1069 return -EINVAL;
1070
1071 ret = rw_verify_area(WRITE, out, &offset, len);
1072 if (unlikely(ret < 0))
1073 return ret;
1074
1075 if (in->f_flags & O_NONBLOCK)
1076 flags |= SPLICE_F_NONBLOCK;
1077
1078 file_start_write(out);
1079 ret = do_splice_from(ipipe, out, &offset, len, flags);
1080 file_end_write(out);
1081
1082 if (!off_out)
1083 out->f_pos = offset;
1084 else
1085 *off_out = offset;
1086
1087 return ret;
1088 }
1089
1090 if (opipe) {
1091 if (off_out)
1092 return -ESPIPE;
1093 if (off_in) {
1094 if (!(in->f_mode & FMODE_PREAD))
1095 return -EINVAL;
1096 offset = *off_in;
1097 } else {
1098 offset = in->f_pos;
1099 }
1100
1101 if (out->f_flags & O_NONBLOCK)
1102 flags |= SPLICE_F_NONBLOCK;
1103
1104 ret = splice_file_to_pipe(in, opipe, &offset, len, flags);
1105 if (!off_in)
1106 in->f_pos = offset;
1107 else
1108 *off_in = offset;
1109
1110 return ret;
1111 }
1112
1113 return -EINVAL;
1114}
1115
1116static long __do_splice(struct file *in, loff_t __user *off_in,
1117 struct file *out, loff_t __user *off_out,
1118 size_t len, unsigned int flags)
1119{
1120 struct pipe_inode_info *ipipe;
1121 struct pipe_inode_info *opipe;
1122 loff_t offset, *__off_in = NULL, *__off_out = NULL;
1123 long ret;
1124
1125 ipipe = get_pipe_info(in, true);
1126 opipe = get_pipe_info(out, true);
1127
1128 if (ipipe && off_in)
1129 return -ESPIPE;
1130 if (opipe && off_out)
1131 return -ESPIPE;
1132
1133 if (off_out) {
1134 if (copy_from_user(&offset, off_out, sizeof(loff_t)))
1135 return -EFAULT;
1136 __off_out = &offset;
1137 }
1138 if (off_in) {
1139 if (copy_from_user(&offset, off_in, sizeof(loff_t)))
1140 return -EFAULT;
1141 __off_in = &offset;
1142 }
1143
1144 ret = do_splice(in, __off_in, out, __off_out, len, flags);
1145 if (ret < 0)
1146 return ret;
1147
1148 if (__off_out && copy_to_user(off_out, __off_out, sizeof(loff_t)))
1149 return -EFAULT;
1150 if (__off_in && copy_to_user(off_in, __off_in, sizeof(loff_t)))
1151 return -EFAULT;
1152
1153 return ret;
1154}
1155
1156static int iter_to_pipe(struct iov_iter *from,
1157 struct pipe_inode_info *pipe,
1158 unsigned flags)
1159{
1160 struct pipe_buffer buf = {
1161 .ops = &user_page_pipe_buf_ops,
1162 .flags = flags
1163 };
1164 size_t total = 0;
1165 int ret = 0;
1166 bool failed = false;
1167
1168 while (iov_iter_count(from) && !failed) {
1169 struct page *pages[16];
1170 ssize_t copied;
1171 size_t start;
1172 int n;
1173
1174 copied = iov_iter_get_pages(from, pages, ~0UL, 16, &start);
1175 if (copied <= 0) {
1176 ret = copied;
1177 break;
1178 }
1179
1180 for (n = 0; copied; n++, start = 0) {
1181 int size = min_t(int, copied, PAGE_SIZE - start);
1182 if (!failed) {
1183 buf.page = pages[n];
1184 buf.offset = start;
1185 buf.len = size;
1186 ret = add_to_pipe(pipe, &buf);
1187 if (unlikely(ret < 0)) {
1188 failed = true;
1189 } else {
1190 iov_iter_advance(from, ret);
1191 total += ret;
1192 }
1193 } else {
1194 put_page(pages[n]);
1195 }
1196 copied -= size;
1197 }
1198 }
1199 return total ? total : ret;
1200}
1201
1202static int pipe_to_user(struct pipe_inode_info *pipe, struct pipe_buffer *buf,
1203 struct splice_desc *sd)
1204{
1205 int n = copy_page_to_iter(buf->page, buf->offset, sd->len, sd->u.data);
1206 return n == sd->len ? n : -EFAULT;
1207}
1208
1209/*
1210 * For lack of a better implementation, implement vmsplice() to userspace
1211 * as a simple copy of the pipes pages to the user iov.
1212 */
1213static long vmsplice_to_user(struct file *file, struct iov_iter *iter,
1214 unsigned int flags)
1215{
1216 struct pipe_inode_info *pipe = get_pipe_info(file, true);
1217 struct splice_desc sd = {
1218 .total_len = iov_iter_count(iter),
1219 .flags = flags,
1220 .u.data = iter
1221 };
1222 long ret = 0;
1223
1224 if (!pipe)
1225 return -EBADF;
1226
1227 if (sd.total_len) {
1228 pipe_lock(pipe);
1229 ret = __splice_from_pipe(pipe, &sd, pipe_to_user);
1230 pipe_unlock(pipe);
1231 }
1232
1233 return ret;
1234}
1235
1236/*
1237 * vmsplice splices a user address range into a pipe. It can be thought of
1238 * as splice-from-memory, where the regular splice is splice-from-file (or
1239 * to file). In both cases the output is a pipe, naturally.
1240 */
1241static long vmsplice_to_pipe(struct file *file, struct iov_iter *iter,
1242 unsigned int flags)
1243{
1244 struct pipe_inode_info *pipe;
1245 long ret = 0;
1246 unsigned buf_flag = 0;
1247
1248 if (flags & SPLICE_F_GIFT)
1249 buf_flag = PIPE_BUF_FLAG_GIFT;
1250
1251 pipe = get_pipe_info(file, true);
1252 if (!pipe)
1253 return -EBADF;
1254
1255 pipe_lock(pipe);
1256 ret = wait_for_space(pipe, flags);
1257 if (!ret)
1258 ret = iter_to_pipe(iter, pipe, buf_flag);
1259 pipe_unlock(pipe);
1260 if (ret > 0)
1261 wakeup_pipe_readers(pipe);
1262 return ret;
1263}
1264
1265static int vmsplice_type(struct fd f, int *type)
1266{
1267 if (!f.file)
1268 return -EBADF;
1269 if (f.file->f_mode & FMODE_WRITE) {
1270 *type = WRITE;
1271 } else if (f.file->f_mode & FMODE_READ) {
1272 *type = READ;
1273 } else {
1274 fdput(f);
1275 return -EBADF;
1276 }
1277 return 0;
1278}
1279
1280/*
1281 * Note that vmsplice only really supports true splicing _from_ user memory
1282 * to a pipe, not the other way around. Splicing from user memory is a simple
1283 * operation that can be supported without any funky alignment restrictions
1284 * or nasty vm tricks. We simply map in the user memory and fill them into
1285 * a pipe. The reverse isn't quite as easy, though. There are two possible
1286 * solutions for that:
1287 *
1288 * - memcpy() the data internally, at which point we might as well just
1289 * do a regular read() on the buffer anyway.
1290 * - Lots of nasty vm tricks, that are neither fast nor flexible (it
1291 * has restriction limitations on both ends of the pipe).
1292 *
1293 * Currently we punt and implement it as a normal copy, see pipe_to_user().
1294 *
1295 */
1296SYSCALL_DEFINE4(vmsplice, int, fd, const struct iovec __user *, uiov,
1297 unsigned long, nr_segs, unsigned int, flags)
1298{
1299 struct iovec iovstack[UIO_FASTIOV];
1300 struct iovec *iov = iovstack;
1301 struct iov_iter iter;
1302 ssize_t error;
1303 struct fd f;
1304 int type;
1305
1306 if (unlikely(flags & ~SPLICE_F_ALL))
1307 return -EINVAL;
1308
1309 f = fdget(fd);
1310 error = vmsplice_type(f, &type);
1311 if (error)
1312 return error;
1313
1314 error = import_iovec(type, uiov, nr_segs,
1315 ARRAY_SIZE(iovstack), &iov, &iter);
1316 if (error < 0)
1317 goto out_fdput;
1318
1319 if (!iov_iter_count(&iter))
1320 error = 0;
1321 else if (iov_iter_rw(&iter) == WRITE)
1322 error = vmsplice_to_pipe(f.file, &iter, flags);
1323 else
1324 error = vmsplice_to_user(f.file, &iter, flags);
1325
1326 kfree(iov);
1327out_fdput:
1328 fdput(f);
1329 return error;
1330}
1331
1332SYSCALL_DEFINE6(splice, int, fd_in, loff_t __user *, off_in,
1333 int, fd_out, loff_t __user *, off_out,
1334 size_t, len, unsigned int, flags)
1335{
1336 struct fd in, out;
1337 long error;
1338
1339 if (unlikely(!len))
1340 return 0;
1341
1342 if (unlikely(flags & ~SPLICE_F_ALL))
1343 return -EINVAL;
1344
1345 error = -EBADF;
1346 in = fdget(fd_in);
1347 if (in.file) {
1348 out = fdget(fd_out);
1349 if (out.file) {
1350 error = __do_splice(in.file, off_in, out.file, off_out,
1351 len, flags);
1352 fdput(out);
1353 }
1354 fdput(in);
1355 }
1356 return error;
1357}
1358
1359/*
1360 * Make sure there's data to read. Wait for input if we can, otherwise
1361 * return an appropriate error.
1362 */
1363static int ipipe_prep(struct pipe_inode_info *pipe, unsigned int flags)
1364{
1365 int ret;
1366
1367 /*
1368 * Check the pipe occupancy without the inode lock first. This function
1369 * is speculative anyways, so missing one is ok.
1370 */
1371 if (!pipe_empty(pipe->head, pipe->tail))
1372 return 0;
1373
1374 ret = 0;
1375 pipe_lock(pipe);
1376
1377 while (pipe_empty(pipe->head, pipe->tail)) {
1378 if (signal_pending(current)) {
1379 ret = -ERESTARTSYS;
1380 break;
1381 }
1382 if (!pipe->writers)
1383 break;
1384 if (flags & SPLICE_F_NONBLOCK) {
1385 ret = -EAGAIN;
1386 break;
1387 }
1388 pipe_wait_readable(pipe);
1389 }
1390
1391 pipe_unlock(pipe);
1392 return ret;
1393}
1394
1395/*
1396 * Make sure there's writeable room. Wait for room if we can, otherwise
1397 * return an appropriate error.
1398 */
1399static int opipe_prep(struct pipe_inode_info *pipe, unsigned int flags)
1400{
1401 int ret;
1402
1403 /*
1404 * Check pipe occupancy without the inode lock first. This function
1405 * is speculative anyways, so missing one is ok.
1406 */
1407 if (!pipe_full(pipe->head, pipe->tail, pipe->max_usage))
1408 return 0;
1409
1410 ret = 0;
1411 pipe_lock(pipe);
1412
1413 while (pipe_full(pipe->head, pipe->tail, pipe->max_usage)) {
1414 if (!pipe->readers) {
1415 send_sig(SIGPIPE, current, 0);
1416 ret = -EPIPE;
1417 break;
1418 }
1419 if (flags & SPLICE_F_NONBLOCK) {
1420 ret = -EAGAIN;
1421 break;
1422 }
1423 if (signal_pending(current)) {
1424 ret = -ERESTARTSYS;
1425 break;
1426 }
1427 pipe_wait_writable(pipe);
1428 }
1429
1430 pipe_unlock(pipe);
1431 return ret;
1432}
1433
1434/*
1435 * Splice contents of ipipe to opipe.
1436 */
1437static int splice_pipe_to_pipe(struct pipe_inode_info *ipipe,
1438 struct pipe_inode_info *opipe,
1439 size_t len, unsigned int flags)
1440{
1441 struct pipe_buffer *ibuf, *obuf;
1442 unsigned int i_head, o_head;
1443 unsigned int i_tail, o_tail;
1444 unsigned int i_mask, o_mask;
1445 int ret = 0;
1446 bool input_wakeup = false;
1447
1448
1449retry:
1450 ret = ipipe_prep(ipipe, flags);
1451 if (ret)
1452 return ret;
1453
1454 ret = opipe_prep(opipe, flags);
1455 if (ret)
1456 return ret;
1457
1458 /*
1459 * Potential ABBA deadlock, work around it by ordering lock
1460 * grabbing by pipe info address. Otherwise two different processes
1461 * could deadlock (one doing tee from A -> B, the other from B -> A).
1462 */
1463 pipe_double_lock(ipipe, opipe);
1464
1465 i_tail = ipipe->tail;
1466 i_mask = ipipe->ring_size - 1;
1467 o_head = opipe->head;
1468 o_mask = opipe->ring_size - 1;
1469
1470 do {
1471 size_t o_len;
1472
1473 if (!opipe->readers) {
1474 send_sig(SIGPIPE, current, 0);
1475 if (!ret)
1476 ret = -EPIPE;
1477 break;
1478 }
1479
1480 i_head = ipipe->head;
1481 o_tail = opipe->tail;
1482
1483 if (pipe_empty(i_head, i_tail) && !ipipe->writers)
1484 break;
1485
1486 /*
1487 * Cannot make any progress, because either the input
1488 * pipe is empty or the output pipe is full.
1489 */
1490 if (pipe_empty(i_head, i_tail) ||
1491 pipe_full(o_head, o_tail, opipe->max_usage)) {
1492 /* Already processed some buffers, break */
1493 if (ret)
1494 break;
1495
1496 if (flags & SPLICE_F_NONBLOCK) {
1497 ret = -EAGAIN;
1498 break;
1499 }
1500
1501 /*
1502 * We raced with another reader/writer and haven't
1503 * managed to process any buffers. A zero return
1504 * value means EOF, so retry instead.
1505 */
1506 pipe_unlock(ipipe);
1507 pipe_unlock(opipe);
1508 goto retry;
1509 }
1510
1511 ibuf = &ipipe->bufs[i_tail & i_mask];
1512 obuf = &opipe->bufs[o_head & o_mask];
1513
1514 if (len >= ibuf->len) {
1515 /*
1516 * Simply move the whole buffer from ipipe to opipe
1517 */
1518 *obuf = *ibuf;
1519 ibuf->ops = NULL;
1520 i_tail++;
1521 ipipe->tail = i_tail;
1522 input_wakeup = true;
1523 o_len = obuf->len;
1524 o_head++;
1525 opipe->head = o_head;
1526 } else {
1527 /*
1528 * Get a reference to this pipe buffer,
1529 * so we can copy the contents over.
1530 */
1531 if (!pipe_buf_get(ipipe, ibuf)) {
1532 if (ret == 0)
1533 ret = -EFAULT;
1534 break;
1535 }
1536 *obuf = *ibuf;
1537
1538 /*
1539 * Don't inherit the gift and merge flags, we need to
1540 * prevent multiple steals of this page.
1541 */
1542 obuf->flags &= ~PIPE_BUF_FLAG_GIFT;
1543 obuf->flags &= ~PIPE_BUF_FLAG_CAN_MERGE;
1544
1545 obuf->len = len;
1546 ibuf->offset += len;
1547 ibuf->len -= len;
1548 o_len = len;
1549 o_head++;
1550 opipe->head = o_head;
1551 }
1552 ret += o_len;
1553 len -= o_len;
1554 } while (len);
1555
1556 pipe_unlock(ipipe);
1557 pipe_unlock(opipe);
1558
1559 /*
1560 * If we put data in the output pipe, wakeup any potential readers.
1561 */
1562 if (ret > 0)
1563 wakeup_pipe_readers(opipe);
1564
1565 if (input_wakeup)
1566 wakeup_pipe_writers(ipipe);
1567
1568 return ret;
1569}
1570
1571/*
1572 * Link contents of ipipe to opipe.
1573 */
1574static int link_pipe(struct pipe_inode_info *ipipe,
1575 struct pipe_inode_info *opipe,
1576 size_t len, unsigned int flags)
1577{
1578 struct pipe_buffer *ibuf, *obuf;
1579 unsigned int i_head, o_head;
1580 unsigned int i_tail, o_tail;
1581 unsigned int i_mask, o_mask;
1582 int ret = 0;
1583
1584 /*
1585 * Potential ABBA deadlock, work around it by ordering lock
1586 * grabbing by pipe info address. Otherwise two different processes
1587 * could deadlock (one doing tee from A -> B, the other from B -> A).
1588 */
1589 pipe_double_lock(ipipe, opipe);
1590
1591 i_tail = ipipe->tail;
1592 i_mask = ipipe->ring_size - 1;
1593 o_head = opipe->head;
1594 o_mask = opipe->ring_size - 1;
1595
1596 do {
1597 if (!opipe->readers) {
1598 send_sig(SIGPIPE, current, 0);
1599 if (!ret)
1600 ret = -EPIPE;
1601 break;
1602 }
1603
1604 i_head = ipipe->head;
1605 o_tail = opipe->tail;
1606
1607 /*
1608 * If we have iterated all input buffers or run out of
1609 * output room, break.
1610 */
1611 if (pipe_empty(i_head, i_tail) ||
1612 pipe_full(o_head, o_tail, opipe->max_usage))
1613 break;
1614
1615 ibuf = &ipipe->bufs[i_tail & i_mask];
1616 obuf = &opipe->bufs[o_head & o_mask];
1617
1618 /*
1619 * Get a reference to this pipe buffer,
1620 * so we can copy the contents over.
1621 */
1622 if (!pipe_buf_get(ipipe, ibuf)) {
1623 if (ret == 0)
1624 ret = -EFAULT;
1625 break;
1626 }
1627
1628 *obuf = *ibuf;
1629
1630 /*
1631 * Don't inherit the gift and merge flag, we need to prevent
1632 * multiple steals of this page.
1633 */
1634 obuf->flags &= ~PIPE_BUF_FLAG_GIFT;
1635 obuf->flags &= ~PIPE_BUF_FLAG_CAN_MERGE;
1636
1637 if (obuf->len > len)
1638 obuf->len = len;
1639 ret += obuf->len;
1640 len -= obuf->len;
1641
1642 o_head++;
1643 opipe->head = o_head;
1644 i_tail++;
1645 } while (len);
1646
1647 pipe_unlock(ipipe);
1648 pipe_unlock(opipe);
1649
1650 /*
1651 * If we put data in the output pipe, wakeup any potential readers.
1652 */
1653 if (ret > 0)
1654 wakeup_pipe_readers(opipe);
1655
1656 return ret;
1657}
1658
1659/*
1660 * This is a tee(1) implementation that works on pipes. It doesn't copy
1661 * any data, it simply references the 'in' pages on the 'out' pipe.
1662 * The 'flags' used are the SPLICE_F_* variants, currently the only
1663 * applicable one is SPLICE_F_NONBLOCK.
1664 */
1665long do_tee(struct file *in, struct file *out, size_t len, unsigned int flags)
1666{
1667 struct pipe_inode_info *ipipe = get_pipe_info(in, true);
1668 struct pipe_inode_info *opipe = get_pipe_info(out, true);
1669 int ret = -EINVAL;
1670
1671 if (unlikely(!(in->f_mode & FMODE_READ) ||
1672 !(out->f_mode & FMODE_WRITE)))
1673 return -EBADF;
1674
1675 /*
1676 * Duplicate the contents of ipipe to opipe without actually
1677 * copying the data.
1678 */
1679 if (ipipe && opipe && ipipe != opipe) {
1680 if ((in->f_flags | out->f_flags) & O_NONBLOCK)
1681 flags |= SPLICE_F_NONBLOCK;
1682
1683 /*
1684 * Keep going, unless we encounter an error. The ipipe/opipe
1685 * ordering doesn't really matter.
1686 */
1687 ret = ipipe_prep(ipipe, flags);
1688 if (!ret) {
1689 ret = opipe_prep(opipe, flags);
1690 if (!ret)
1691 ret = link_pipe(ipipe, opipe, len, flags);
1692 }
1693 }
1694
1695 return ret;
1696}
1697
1698SYSCALL_DEFINE4(tee, int, fdin, int, fdout, size_t, len, unsigned int, flags)
1699{
1700 struct fd in, out;
1701 int error;
1702
1703 if (unlikely(flags & ~SPLICE_F_ALL))
1704 return -EINVAL;
1705
1706 if (unlikely(!len))
1707 return 0;
1708
1709 error = -EBADF;
1710 in = fdget(fdin);
1711 if (in.file) {
1712 out = fdget(fdout);
1713 if (out.file) {
1714 error = do_tee(in.file, out.file, len, flags);
1715 fdput(out);
1716 }
1717 fdput(in);
1718 }
1719
1720 return error;
1721}