1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * linux/fs/pipe.c
4 *
5 * Copyright (C) 1991, 1992, 1999 Linus Torvalds
6 */
7
8 #include <linux/mm.h>
9 #include <linux/file.h>
10 #include <linux/poll.h>
11 #include <linux/slab.h>
12 #include <linux/module.h>
13 #include <linux/init.h>
14 #include <linux/fs.h>
15 #include <linux/log2.h>
16 #include <linux/mount.h>
17 #include <linux/pseudo_fs.h>
18 #include <linux/magic.h>
19 #include <linux/pipe_fs_i.h>
20 #include <linux/uio.h>
21 #include <linux/highmem.h>
22 #include <linux/pagemap.h>
23 #include <linux/audit.h>
24 #include <linux/syscalls.h>
25 #include <linux/fcntl.h>
26 #include <linux/memcontrol.h>
27 #include <linux/watch_queue.h>
28 #include <linux/sysctl.h>
29
30 #include <linux/uaccess.h>
31 #include <asm/ioctls.h>
32
33 #include "internal.h"
34
35 /*
36 * New pipe buffers will be restricted to this size while the user is exceeding
37 * their pipe buffer quota. The general pipe use case needs at least two
38 * buffers: one for data yet to be read, and one for new data. If this is less
39 * than two, then a write to a non-empty pipe may block even if the pipe is not
40 * full. This can occur with GNU make jobserver or similar uses of pipes as
41 * semaphores: multiple processes may be waiting to write tokens back to the
42 * pipe before reading tokens: https://lore.kernel.org/lkml/1628086770.5rn8p04n6j.none@localhost/.
43 *
44 * Users can reduce their pipe buffers with F_SETPIPE_SZ below this at their
45 * own risk, namely: pipe writes to non-full pipes may block until the pipe is
46 * emptied.
47 */
48 #define PIPE_MIN_DEF_BUFFERS 2
49
50 /*
51 * The max size that a non-root user is allowed to grow the pipe. Can
52 * be set by root in /proc/sys/fs/pipe-max-size
53 */
54 static unsigned int pipe_max_size = 1048576;
55
56 /* Maximum allocatable pages per user. Hard limit is unset by default, soft
57 * matches default values.
58 */
59 static unsigned long pipe_user_pages_hard;
60 static unsigned long pipe_user_pages_soft = PIPE_DEF_BUFFERS * INR_OPEN_CUR;
61
62 /*
63 * We use head and tail indices that aren't masked off, except at the point of
64 * dereference, but rather they're allowed to wrap naturally. This means there
65 * isn't a dead spot in the buffer, but the ring has to be a power of two and
66 * <= 2^31.
67 * -- David Howells 2019-09-23.
68 *
69 * Reads with count = 0 should always return 0.
70 * -- Julian Bradfield 1999-06-07.
71 *
72 * FIFOs and Pipes now generate SIGIO for both readers and writers.
73 * -- Jeremy Elson <jelson@circlemud.org> 2001-08-16
74 *
75 * pipe_read & write cleanup
76 * -- Manfred Spraul <manfred@colorfullife.com> 2002-05-09
77 */
78
79 #define cmp_int(l, r) ((l > r) - (l < r))
80
81 #ifdef CONFIG_PROVE_LOCKING
82 static int pipe_lock_cmp_fn(const struct lockdep_map *a,
83 const struct lockdep_map *b)
84 {
85 return cmp_int((unsigned long) a, (unsigned long) b);
86 }
87 #endif
88
89 void pipe_lock(struct pipe_inode_info *pipe)
90 {
91 if (pipe->files)
92 mutex_lock(&pipe->mutex);
93 }
94 EXPORT_SYMBOL(pipe_lock);
95
96 void pipe_unlock(struct pipe_inode_info *pipe)
97 {
98 if (pipe->files)
99 mutex_unlock(&pipe->mutex);
100 }
101 EXPORT_SYMBOL(pipe_unlock);
102
103 void pipe_double_lock(struct pipe_inode_info *pipe1,
104 struct pipe_inode_info *pipe2)
105 {
106 BUG_ON(pipe1 == pipe2);
107
108 if (pipe1 > pipe2)
109 swap(pipe1, pipe2);
110
111 pipe_lock(pipe1);
112 pipe_lock(pipe2);
113 }
114
115 static void anon_pipe_buf_release(struct pipe_inode_info *pipe,
116 struct pipe_buffer *buf)
117 {
118 struct page *page = buf->page;
119
120 /*
121 * If nobody else uses this page, and we don't already have a
122 * temporary page, let's keep track of it as a one-deep
123 * allocation cache. (Otherwise just release our reference to it)
124 */
125 if (page_count(page) == 1 && !pipe->tmp_page)
126 pipe->tmp_page = page;
127 else
128 put_page(page);
129 }
130
131 static bool anon_pipe_buf_try_steal(struct pipe_inode_info *pipe,
132 struct pipe_buffer *buf)
133 {
134 struct page *page = buf->page;
135
136 if (page_count(page) != 1)
137 return false;
138 memcg_kmem_uncharge_page(page, 0);
139 __SetPageLocked(page);
140 return true;
141 }
142
143 /**
144 * generic_pipe_buf_try_steal - attempt to take ownership of a &pipe_buffer
145 * @pipe: the pipe that the buffer belongs to
146 * @buf: the buffer to attempt to steal
147 *
148 * Description:
149 * This function attempts to steal the &struct page attached to
150 * @buf. If successful, this function returns 0 and returns with
151 * the page locked. The caller may then reuse the page for whatever
152 * he wishes; the typical use is insertion into a different file
153 * page cache.
154 */
155 bool generic_pipe_buf_try_steal(struct pipe_inode_info *pipe,
156 struct pipe_buffer *buf)
157 {
158 struct page *page = buf->page;
159
160 /*
161 * A reference of one is golden, that means that the owner of this
162 * page is the only one holding a reference to it. lock the page
163 * and return OK.
164 */
165 if (page_count(page) == 1) {
166 lock_page(page);
167 return true;
168 }
169 return false;
170 }
171 EXPORT_SYMBOL(generic_pipe_buf_try_steal);
172
173 /**
174 * generic_pipe_buf_get - get a reference to a &struct pipe_buffer
175 * @pipe: the pipe that the buffer belongs to
176 * @buf: the buffer to get a reference to
177 *
178 * Description:
179 * This function grabs an extra reference to @buf. It's used in
180 * the tee() system call, when we duplicate the buffers in one
181 * pipe into another.
182 */
183 bool generic_pipe_buf_get(struct pipe_inode_info *pipe, struct pipe_buffer *buf)
184 {
185 return try_get_page(buf->page);
186 }
187 EXPORT_SYMBOL(generic_pipe_buf_get);
188
189 /**
190 * generic_pipe_buf_release - put a reference to a &struct pipe_buffer
191 * @pipe: the pipe that the buffer belongs to
192 * @buf: the buffer to put a reference to
193 *
194 * Description:
195 * This function releases a reference to @buf.
196 */
197 void generic_pipe_buf_release(struct pipe_inode_info *pipe,
198 struct pipe_buffer *buf)
199 {
200 put_page(buf->page);
201 }
202 EXPORT_SYMBOL(generic_pipe_buf_release);
203
204 static const struct pipe_buf_operations anon_pipe_buf_ops = {
205 .release = anon_pipe_buf_release,
206 .try_steal = anon_pipe_buf_try_steal,
207 .get = generic_pipe_buf_get,
208 };
209
210 /* Done while waiting without holding the pipe lock - thus the READ_ONCE() */
211 static inline bool pipe_readable(const struct pipe_inode_info *pipe)
212 {
213 unsigned int head = READ_ONCE(pipe->head);
214 unsigned int tail = READ_ONCE(pipe->tail);
215 unsigned int writers = READ_ONCE(pipe->writers);
216
217 return !pipe_empty(head, tail) || !writers;
218 }
219
220 static inline unsigned int pipe_update_tail(struct pipe_inode_info *pipe,
221 struct pipe_buffer *buf,
222 unsigned int tail)
223 {
224 pipe_buf_release(pipe, buf);
225
226 /*
227 * If the pipe has a watch_queue, we need additional protection
228 * by the spinlock because notifications get posted with only
229 * this spinlock, no mutex
230 */
231 if (pipe_has_watch_queue(pipe)) {
232 spin_lock_irq(&pipe->rd_wait.lock);
233 #ifdef CONFIG_WATCH_QUEUE
234 if (buf->flags & PIPE_BUF_FLAG_LOSS)
235 pipe->note_loss = true;
236 #endif
237 pipe->tail = ++tail;
238 spin_unlock_irq(&pipe->rd_wait.lock);
239 return tail;
240 }
241
242 /*
243 * Without a watch_queue, we can simply increment the tail
244 * without the spinlock - the mutex is enough.
245 */
246 pipe->tail = ++tail;
247 return tail;
248 }
249
250 static ssize_t
251 pipe_read(struct kiocb *iocb, struct iov_iter *to)
252 {
253 size_t total_len = iov_iter_count(to);
254 struct file *filp = iocb->ki_filp;
255 struct pipe_inode_info *pipe = filp->private_data;
256 bool was_full, wake_next_reader = false;
257 ssize_t ret;
258
259 /* Null read succeeds. */
260 if (unlikely(total_len == 0))
261 return 0;
262
263 ret = 0;
264 mutex_lock(&pipe->mutex);
265
266 /*
267 * We only wake up writers if the pipe was full when we started
268 * reading in order to avoid unnecessary wakeups.
269 *
270 * But when we do wake up writers, we do so using a sync wakeup
271 * (WF_SYNC), because we want them to get going and generate more
272 * data for us.
273 */
274 was_full = pipe_full(pipe->head, pipe->tail, pipe->max_usage);
275 for (;;) {
276 /* Read ->head with a barrier vs post_one_notification() */
277 unsigned int head = smp_load_acquire(&pipe->head);
278 unsigned int tail = pipe->tail;
279 unsigned int mask = pipe->ring_size - 1;
280
281 #ifdef CONFIG_WATCH_QUEUE
282 if (pipe->note_loss) {
283 struct watch_notification n;
284
285 if (total_len < 8) {
286 if (ret == 0)
287 ret = -ENOBUFS;
288 break;
289 }
290
291 n.type = WATCH_TYPE_META;
292 n.subtype = WATCH_META_LOSS_NOTIFICATION;
293 n.info = watch_sizeof(n);
294 if (copy_to_iter(&n, sizeof(n), to) != sizeof(n)) {
295 if (ret == 0)
296 ret = -EFAULT;
297 break;
298 }
299 ret += sizeof(n);
300 total_len -= sizeof(n);
301 pipe->note_loss = false;
302 }
303 #endif
304
305 if (!pipe_empty(head, tail)) {
306 struct pipe_buffer *buf = &pipe->bufs[tail & mask];
307 size_t chars = buf->len;
308 size_t written;
309 int error;
310
311 if (chars > total_len) {
312 if (buf->flags & PIPE_BUF_FLAG_WHOLE) {
313 if (ret == 0)
314 ret = -ENOBUFS;
315 break;
316 }
317 chars = total_len;
318 }
319
320 error = pipe_buf_confirm(pipe, buf);
321 if (error) {
322 if (!ret)
323 ret = error;
324 break;
325 }
326
327 written = copy_page_to_iter(buf->page, buf->offset, chars, to);
328 if (unlikely(written < chars)) {
329 if (!ret)
330 ret = -EFAULT;
331 break;
332 }
333 ret += chars;
334 buf->offset += chars;
335 buf->len -= chars;
336
337 /* Was it a packet buffer? Clean up and exit */
338 if (buf->flags & PIPE_BUF_FLAG_PACKET) {
339 total_len = chars;
340 buf->len = 0;
341 }
342
343 if (!buf->len)
344 tail = pipe_update_tail(pipe, buf, tail);
345 total_len -= chars;
346 if (!total_len)
347 break; /* common path: read succeeded */
348 if (!pipe_empty(head, tail)) /* More to do? */
349 continue;
350 }
351
352 if (!pipe->writers)
353 break;
354 if (ret)
355 break;
356 if ((filp->f_flags & O_NONBLOCK) ||
357 (iocb->ki_flags & IOCB_NOWAIT)) {
358 ret = -EAGAIN;
359 break;
360 }
361 mutex_unlock(&pipe->mutex);
362
363 /*
364 * We only get here if we didn't actually read anything.
365 *
366 * However, we could have seen (and removed) a zero-sized
367 * pipe buffer, and might have made space in the buffers
368 * that way.
369 *
370 * You can't make zero-sized pipe buffers by doing an empty
371 * write (not even in packet mode), but they can happen if
372 * the writer gets an EFAULT when trying to fill a buffer
373 * that already got allocated and inserted in the buffer
374 * array.
375 *
376 * So we still need to wake up any pending writers in the
377 * _very_ unlikely case that the pipe was full, but we got
378 * no data.
379 */
380 if (unlikely(was_full))
381 wake_up_interruptible_sync_poll(&pipe->wr_wait, EPOLLOUT | EPOLLWRNORM);
382 kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT);
383
384 /*
385 * But because we didn't read anything, at this point we can
386 * just return directly with -ERESTARTSYS if we're interrupted,
387 * since we've done any required wakeups and there's no need
388 * to mark anything accessed. And we've dropped the lock.
389 */
390 if (wait_event_interruptible_exclusive(pipe->rd_wait, pipe_readable(pipe)) < 0)
391 return -ERESTARTSYS;
392
393 mutex_lock(&pipe->mutex);
394 was_full = pipe_full(pipe->head, pipe->tail, pipe->max_usage);
395 wake_next_reader = true;
396 }
397 if (pipe_empty(pipe->head, pipe->tail))
398 wake_next_reader = false;
399 mutex_unlock(&pipe->mutex);
400
401 if (was_full)
402 wake_up_interruptible_sync_poll(&pipe->wr_wait, EPOLLOUT | EPOLLWRNORM);
403 if (wake_next_reader)
404 wake_up_interruptible_sync_poll(&pipe->rd_wait, EPOLLIN | EPOLLRDNORM);
405 kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT);
406 if (ret > 0)
407 file_accessed(filp);
408 return ret;
409 }
410
411 static inline int is_packetized(struct file *file)
412 {
413 return (file->f_flags & O_DIRECT) != 0;
414 }
415
416 /* Done while waiting without holding the pipe lock - thus the READ_ONCE() */
417 static inline bool pipe_writable(const struct pipe_inode_info *pipe)
418 {
419 unsigned int head = READ_ONCE(pipe->head);
420 unsigned int tail = READ_ONCE(pipe->tail);
421 unsigned int max_usage = READ_ONCE(pipe->max_usage);
422
423 return !pipe_full(head, tail, max_usage) ||
424 !READ_ONCE(pipe->readers);
425 }
426
427 static ssize_t
428 pipe_write(struct kiocb *iocb, struct iov_iter *from)
429 {
430 struct file *filp = iocb->ki_filp;
431 struct pipe_inode_info *pipe = filp->private_data;
432 unsigned int head;
433 ssize_t ret = 0;
434 size_t total_len = iov_iter_count(from);
435 ssize_t chars;
436 bool was_empty = false;
437 bool wake_next_writer = false;
438
439 /*
440 * Reject writing to watch queue pipes before the point where we lock
441 * the pipe.
442 * Otherwise, lockdep would be unhappy if the caller already has another
443 * pipe locked.
444 * If we had to support locking a normal pipe and a notification pipe at
445 * the same time, we could set up lockdep annotations for that, but
446 * since we don't actually need that, it's simpler to just bail here.
447 */
448 if (pipe_has_watch_queue(pipe))
449 return -EXDEV;
450
451 /* Null write succeeds. */
452 if (unlikely(total_len == 0))
453 return 0;
454
455 mutex_lock(&pipe->mutex);
456
457 if (!pipe->readers) {
458 send_sig(SIGPIPE, current, 0);
459 ret = -EPIPE;
460 goto out;
461 }
462
463 /*
464 * If it wasn't empty we try to merge new data into
465 * the last buffer.
466 *
467 * That naturally merges small writes, but it also
468 * page-aligns the rest of the writes for large writes
469 * spanning multiple pages.
470 */
471 head = pipe->head;
472 was_empty = pipe_empty(head, pipe->tail);
473 chars = total_len & (PAGE_SIZE-1);
474 if (chars && !was_empty) {
475 unsigned int mask = pipe->ring_size - 1;
476 struct pipe_buffer *buf = &pipe->bufs[(head - 1) & mask];
477 int offset = buf->offset + buf->len;
478
479 if ((buf->flags & PIPE_BUF_FLAG_CAN_MERGE) &&
480 offset + chars <= PAGE_SIZE) {
481 ret = pipe_buf_confirm(pipe, buf);
482 if (ret)
483 goto out;
484
485 ret = copy_page_from_iter(buf->page, offset, chars, from);
486 if (unlikely(ret < chars)) {
487 ret = -EFAULT;
488 goto out;
489 }
490
491 buf->len += ret;
492 if (!iov_iter_count(from))
493 goto out;
494 }
495 }
496
497 for (;;) {
498 if (!pipe->readers) {
499 send_sig(SIGPIPE, current, 0);
500 if (!ret)
501 ret = -EPIPE;
502 break;
503 }
504
505 head = pipe->head;
506 if (!pipe_full(head, pipe->tail, pipe->max_usage)) {
507 unsigned int mask = pipe->ring_size - 1;
508 struct pipe_buffer *buf;
509 struct page *page = pipe->tmp_page;
510 int copied;
511
512 if (!page) {
513 page = alloc_page(GFP_HIGHUSER | __GFP_ACCOUNT);
514 if (unlikely(!page)) {
515 ret = ret ? : -ENOMEM;
516 break;
517 }
518 pipe->tmp_page = page;
519 }
520
521 /* Allocate a slot in the ring in advance and attach an
522 * empty buffer. If we fault or otherwise fail to use
523 * it, either the reader will consume it or it'll still
524 * be there for the next write.
525 */
526 pipe->head = head + 1;
527
528 /* Insert it into the buffer array */
529 buf = &pipe->bufs[head & mask];
530 buf->page = page;
531 buf->ops = &anon_pipe_buf_ops;
532 buf->offset = 0;
533 buf->len = 0;
534 if (is_packetized(filp))
535 buf->flags = PIPE_BUF_FLAG_PACKET;
536 else
537 buf->flags = PIPE_BUF_FLAG_CAN_MERGE;
538 pipe->tmp_page = NULL;
539
540 copied = copy_page_from_iter(page, 0, PAGE_SIZE, from);
541 if (unlikely(copied < PAGE_SIZE && iov_iter_count(from))) {
542 if (!ret)
543 ret = -EFAULT;
544 break;
545 }
546 ret += copied;
547 buf->len = copied;
548
549 if (!iov_iter_count(from))
550 break;
551 }
552
553 if (!pipe_full(head, pipe->tail, pipe->max_usage))
554 continue;
555
556 /* Wait for buffer space to become available. */
557 if ((filp->f_flags & O_NONBLOCK) ||
558 (iocb->ki_flags & IOCB_NOWAIT)) {
559 if (!ret)
560 ret = -EAGAIN;
561 break;
562 }
563 if (signal_pending(current)) {
564 if (!ret)
565 ret = -ERESTARTSYS;
566 break;
567 }
568
569 /*
570 * We're going to release the pipe lock and wait for more
571 * space. We wake up any readers if necessary, and then
572 * after waiting we need to re-check whether the pipe
573 * become empty while we dropped the lock.
574 */
575 mutex_unlock(&pipe->mutex);
576 if (was_empty)
577 wake_up_interruptible_sync_poll(&pipe->rd_wait, EPOLLIN | EPOLLRDNORM);
578 kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
579 wait_event_interruptible_exclusive(pipe->wr_wait, pipe_writable(pipe));
580 mutex_lock(&pipe->mutex);
581 was_empty = pipe_empty(pipe->head, pipe->tail);
582 wake_next_writer = true;
583 }
584 out:
585 if (pipe_full(pipe->head, pipe->tail, pipe->max_usage))
586 wake_next_writer = false;
587 mutex_unlock(&pipe->mutex);
588
589 /*
590 * If we do do a wakeup event, we do a 'sync' wakeup, because we
591 * want the reader to start processing things asap, rather than
592 * leave the data pending.
593 *
594 * This is particularly important for small writes, because of
595 * how (for example) the GNU make jobserver uses small writes to
596 * wake up pending jobs
597 *
598 * Epoll nonsensically wants a wakeup whether the pipe
599 * was already empty or not.
600 */
601 if (was_empty || pipe->poll_usage)
602 wake_up_interruptible_sync_poll(&pipe->rd_wait, EPOLLIN | EPOLLRDNORM);
603 kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
604 if (wake_next_writer)
605 wake_up_interruptible_sync_poll(&pipe->wr_wait, EPOLLOUT | EPOLLWRNORM);
606 if (ret > 0 && sb_start_write_trylock(file_inode(filp)->i_sb)) {
607 int err = file_update_time(filp);
608 if (err)
609 ret = err;
610 sb_end_write(file_inode(filp)->i_sb);
611 }
612 return ret;
613 }
614
615 static long pipe_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
616 {
617 struct pipe_inode_info *pipe = filp->private_data;
618 unsigned int count, head, tail, mask;
619
620 switch (cmd) {
621 case FIONREAD:
622 mutex_lock(&pipe->mutex);
623 count = 0;
624 head = pipe->head;
625 tail = pipe->tail;
626 mask = pipe->ring_size - 1;
627
628 while (tail != head) {
629 count += pipe->bufs[tail & mask].len;
630 tail++;
631 }
632 mutex_unlock(&pipe->mutex);
633
634 return put_user(count, (int __user *)arg);
635
636 #ifdef CONFIG_WATCH_QUEUE
637 case IOC_WATCH_QUEUE_SET_SIZE: {
638 int ret;
639 mutex_lock(&pipe->mutex);
640 ret = watch_queue_set_size(pipe, arg);
641 mutex_unlock(&pipe->mutex);
642 return ret;
643 }
644
645 case IOC_WATCH_QUEUE_SET_FILTER:
646 return watch_queue_set_filter(
647 pipe, (struct watch_notification_filter __user *)arg);
648 #endif
649
650 default:
651 return -ENOIOCTLCMD;
652 }
653 }
654
655 /* No kernel lock held - fine */
656 static __poll_t
657 pipe_poll(struct file *filp, poll_table *wait)
658 {
659 __poll_t mask;
660 struct pipe_inode_info *pipe = filp->private_data;
661 unsigned int head, tail;
662
663 /* Epoll has some historical nasty semantics, this enables them */
664 WRITE_ONCE(pipe->poll_usage, true);
665
666 /*
667 * Reading pipe state only -- no need for acquiring the semaphore.
668 *
669 * But because this is racy, the code has to add the
670 * entry to the poll table _first_ ..
671 */
672 if (filp->f_mode & FMODE_READ)
673 poll_wait(filp, &pipe->rd_wait, wait);
674 if (filp->f_mode & FMODE_WRITE)
675 poll_wait(filp, &pipe->wr_wait, wait);
676
677 /*
678 * .. and only then can you do the racy tests. That way,
679 * if something changes and you got it wrong, the poll
680 * table entry will wake you up and fix it.
681 */
682 head = READ_ONCE(pipe->head);
683 tail = READ_ONCE(pipe->tail);
684
685 mask = 0;
686 if (filp->f_mode & FMODE_READ) {
687 if (!pipe_empty(head, tail))
688 mask |= EPOLLIN | EPOLLRDNORM;
689 if (!pipe->writers && filp->f_version != pipe->w_counter)
690 mask |= EPOLLHUP;
691 }
692
693 if (filp->f_mode & FMODE_WRITE) {
694 if (!pipe_full(head, tail, pipe->max_usage))
695 mask |= EPOLLOUT | EPOLLWRNORM;
696 /*
697 * Most Unices do not set EPOLLERR for FIFOs but on Linux they
698 * behave exactly like pipes for poll().
699 */
700 if (!pipe->readers)
701 mask |= EPOLLERR;
702 }
703
704 return mask;
705 }
706
707 static void put_pipe_info(struct inode *inode, struct pipe_inode_info *pipe)
708 {
709 int kill = 0;
710
711 spin_lock(&inode->i_lock);
712 if (!--pipe->files) {
713 inode->i_pipe = NULL;
714 kill = 1;
715 }
716 spin_unlock(&inode->i_lock);
717
718 if (kill)
719 free_pipe_info(pipe);
720 }
721
722 static int
723 pipe_release(struct inode *inode, struct file *file)
724 {
725 struct pipe_inode_info *pipe = file->private_data;
726
727 mutex_lock(&pipe->mutex);
728 if (file->f_mode & FMODE_READ)
729 pipe->readers--;
730 if (file->f_mode & FMODE_WRITE)
731 pipe->writers--;
732
733 /* Was that the last reader or writer, but not the other side? */
734 if (!pipe->readers != !pipe->writers) {
735 wake_up_interruptible_all(&pipe->rd_wait);
736 wake_up_interruptible_all(&pipe->wr_wait);
737 kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
738 kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT);
739 }
740 mutex_unlock(&pipe->mutex);
741
742 put_pipe_info(inode, pipe);
743 return 0;
744 }
745
746 static int
747 pipe_fasync(int fd, struct file *filp, int on)
748 {
749 struct pipe_inode_info *pipe = filp->private_data;
750 int retval = 0;
751
752 mutex_lock(&pipe->mutex);
753 if (filp->f_mode & FMODE_READ)
754 retval = fasync_helper(fd, filp, on, &pipe->fasync_readers);
755 if ((filp->f_mode & FMODE_WRITE) && retval >= 0) {
756 retval = fasync_helper(fd, filp, on, &pipe->fasync_writers);
757 if (retval < 0 && (filp->f_mode & FMODE_READ))
758 /* this can happen only if on == T */
759 fasync_helper(-1, filp, 0, &pipe->fasync_readers);
760 }
761 mutex_unlock(&pipe->mutex);
762 return retval;
763 }
764
765 unsigned long account_pipe_buffers(struct user_struct *user,
766 unsigned long old, unsigned long new)
767 {
768 return atomic_long_add_return(new - old, &user->pipe_bufs);
769 }
770
771 bool too_many_pipe_buffers_soft(unsigned long user_bufs)
772 {
773 unsigned long soft_limit = READ_ONCE(pipe_user_pages_soft);
774
775 return soft_limit && user_bufs > soft_limit;
776 }
777
778 bool too_many_pipe_buffers_hard(unsigned long user_bufs)
779 {
780 unsigned long hard_limit = READ_ONCE(pipe_user_pages_hard);
781
782 return hard_limit && user_bufs > hard_limit;
783 }
784
785 bool pipe_is_unprivileged_user(void)
786 {
787 return !capable(CAP_SYS_RESOURCE) && !capable(CAP_SYS_ADMIN);
788 }
789
790 struct pipe_inode_info *alloc_pipe_info(void)
791 {
792 struct pipe_inode_info *pipe;
793 unsigned long pipe_bufs = PIPE_DEF_BUFFERS;
794 struct user_struct *user = get_current_user();
795 unsigned long user_bufs;
796 unsigned int max_size = READ_ONCE(pipe_max_size);
797
798 pipe = kzalloc(sizeof(struct pipe_inode_info), GFP_KERNEL_ACCOUNT);
799 if (pipe == NULL)
800 goto out_free_uid;
801
802 if (pipe_bufs * PAGE_SIZE > max_size && !capable(CAP_SYS_RESOURCE))
803 pipe_bufs = max_size >> PAGE_SHIFT;
804
805 user_bufs = account_pipe_buffers(user, 0, pipe_bufs);
806
807 if (too_many_pipe_buffers_soft(user_bufs) && pipe_is_unprivileged_user()) {
808 user_bufs = account_pipe_buffers(user, pipe_bufs, PIPE_MIN_DEF_BUFFERS);
809 pipe_bufs = PIPE_MIN_DEF_BUFFERS;
810 }
811
812 if (too_many_pipe_buffers_hard(user_bufs) && pipe_is_unprivileged_user())
813 goto out_revert_acct;
814
815 pipe->bufs = kcalloc(pipe_bufs, sizeof(struct pipe_buffer),
816 GFP_KERNEL_ACCOUNT);
817
818 if (pipe->bufs) {
819 init_waitqueue_head(&pipe->rd_wait);
820 init_waitqueue_head(&pipe->wr_wait);
821 pipe->r_counter = pipe->w_counter = 1;
822 pipe->max_usage = pipe_bufs;
823 pipe->ring_size = pipe_bufs;
824 pipe->nr_accounted = pipe_bufs;
825 pipe->user = user;
826 mutex_init(&pipe->mutex);
827 lock_set_cmp_fn(&pipe->mutex, pipe_lock_cmp_fn, NULL);
828 return pipe;
829 }
830
831 out_revert_acct:
832 (void) account_pipe_buffers(user, pipe_bufs, 0);
833 kfree(pipe);
834 out_free_uid:
835 free_uid(user);
836 return NULL;
837 }
838
839 void free_pipe_info(struct pipe_inode_info *pipe)
840 {
841 unsigned int i;
842
843 #ifdef CONFIG_WATCH_QUEUE
844 if (pipe->watch_queue)
845 watch_queue_clear(pipe->watch_queue);
846 #endif
847
848 (void) account_pipe_buffers(pipe->user, pipe->nr_accounted, 0);
849 free_uid(pipe->user);
850 for (i = 0; i < pipe->ring_size; i++) {
851 struct pipe_buffer *buf = pipe->bufs + i;
852 if (buf->ops)
853 pipe_buf_release(pipe, buf);
854 }
855 #ifdef CONFIG_WATCH_QUEUE
856 if (pipe->watch_queue)
857 put_watch_queue(pipe->watch_queue);
858 #endif
859 if (pipe->tmp_page)
860 __free_page(pipe->tmp_page);
861 kfree(pipe->bufs);
862 kfree(pipe);
863 }
864
865 static struct vfsmount *pipe_mnt __ro_after_init;
866
867 /*
868 * pipefs_dname() is called from d_path().
869 */
870 static char *pipefs_dname(struct dentry *dentry, char *buffer, int buflen)
871 {
872 return dynamic_dname(buffer, buflen, "pipe:[%lu]",
873 d_inode(dentry)->i_ino);
874 }
875
876 static const struct dentry_operations pipefs_dentry_operations = {
877 .d_dname = pipefs_dname,
878 };
879
880 static struct inode * get_pipe_inode(void)
881 {
882 struct inode *inode = new_inode_pseudo(pipe_mnt->mnt_sb);
883 struct pipe_inode_info *pipe;
884
885 if (!inode)
886 goto fail_inode;
887
888 inode->i_ino = get_next_ino();
889
890 pipe = alloc_pipe_info();
891 if (!pipe)
892 goto fail_iput;
893
894 inode->i_pipe = pipe;
895 pipe->files = 2;
896 pipe->readers = pipe->writers = 1;
897 inode->i_fop = &pipefifo_fops;
898
899 /*
900 * Mark the inode dirty from the very beginning,
901 * that way it will never be moved to the dirty
902 * list because "mark_inode_dirty()" will think
903 * that it already _is_ on the dirty list.
904 */
905 inode->i_state = I_DIRTY;
906 inode->i_mode = S_IFIFO | S_IRUSR | S_IWUSR;
907 inode->i_uid = current_fsuid();
908 inode->i_gid = current_fsgid();
909 simple_inode_init_ts(inode);
910
911 return inode;
912
913 fail_iput:
914 iput(inode);
915
916 fail_inode:
917 return NULL;
918 }
919
920 int create_pipe_files(struct file **res, int flags)
921 {
922 struct inode *inode = get_pipe_inode();
923 struct file *f;
924 int error;
925
926 if (!inode)
927 return -ENFILE;
928
929 if (flags & O_NOTIFICATION_PIPE) {
930 error = watch_queue_init(inode->i_pipe);
931 if (error) {
932 free_pipe_info(inode->i_pipe);
933 iput(inode);
934 return error;
935 }
936 }
937
938 f = alloc_file_pseudo(inode, pipe_mnt, "",
939 O_WRONLY | (flags & (O_NONBLOCK | O_DIRECT)),
940 &pipefifo_fops);
941 if (IS_ERR(f)) {
942 free_pipe_info(inode->i_pipe);
943 iput(inode);
944 return PTR_ERR(f);
945 }
946
947 f->private_data = inode->i_pipe;
948
949 res[0] = alloc_file_clone(f, O_RDONLY | (flags & O_NONBLOCK),
950 &pipefifo_fops);
951 if (IS_ERR(res[0])) {
952 put_pipe_info(inode, inode->i_pipe);
953 fput(f);
954 return PTR_ERR(res[0]);
955 }
956 res[0]->private_data = inode->i_pipe;
957 res[1] = f;
958 stream_open(inode, res[0]);
959 stream_open(inode, res[1]);
960 return 0;
961 }
962
963 static int __do_pipe_flags(int *fd, struct file **files, int flags)
964 {
965 int error;
966 int fdw, fdr;
967
968 if (flags & ~(O_CLOEXEC | O_NONBLOCK | O_DIRECT | O_NOTIFICATION_PIPE))
969 return -EINVAL;
970
971 error = create_pipe_files(files, flags);
972 if (error)
973 return error;
974
975 error = get_unused_fd_flags(flags);
976 if (error < 0)
977 goto err_read_pipe;
978 fdr = error;
979
980 error = get_unused_fd_flags(flags);
981 if (error < 0)
982 goto err_fdr;
983 fdw = error;
984
985 audit_fd_pair(fdr, fdw);
986 fd[0] = fdr;
987 fd[1] = fdw;
988 /* pipe groks IOCB_NOWAIT */
989 files[0]->f_mode |= FMODE_NOWAIT;
990 files[1]->f_mode |= FMODE_NOWAIT;
991 return 0;
992
993 err_fdr:
994 put_unused_fd(fdr);
995 err_read_pipe:
996 fput(files[0]);
997 fput(files[1]);
998 return error;
999 }
1000
1001 int do_pipe_flags(int *fd, int flags)
1002 {
1003 struct file *files[2];
1004 int error = __do_pipe_flags(fd, files, flags);
1005 if (!error) {
1006 fd_install(fd[0], files[0]);
1007 fd_install(fd[1], files[1]);
1008 }
1009 return error;
1010 }
1011
1012 /*
1013 * sys_pipe() is the normal C calling standard for creating
1014 * a pipe. It's not the way Unix traditionally does this, though.
1015 */
1016 static int do_pipe2(int __user *fildes, int flags)
1017 {
1018 struct file *files[2];
1019 int fd[2];
1020 int error;
1021
1022 error = __do_pipe_flags(fd, files, flags);
1023 if (!error) {
1024 if (unlikely(copy_to_user(fildes, fd, sizeof(fd)))) {
1025 fput(files[0]);
1026 fput(files[1]);
1027 put_unused_fd(fd[0]);
1028 put_unused_fd(fd[1]);
1029 error = -EFAULT;
1030 } else {
1031 fd_install(fd[0], files[0]);
1032 fd_install(fd[1], files[1]);
1033 }
1034 }
1035 return error;
1036 }
1037
1038 SYSCALL_DEFINE2(pipe2, int __user *, fildes, int, flags)
1039 {
1040 return do_pipe2(fildes, flags);
1041 }
1042
1043 SYSCALL_DEFINE1(pipe, int __user *, fildes)
1044 {
1045 return do_pipe2(fildes, 0);
1046 }
1047
1048 /*
1049 * This is the stupid "wait for pipe to be readable or writable"
1050 * model.
1051 *
1052 * See pipe_read/write() for the proper kind of exclusive wait,
1053 * but that requires that we wake up any other readers/writers
1054 * if we then do not end up reading everything (ie the whole
1055 * "wake_next_reader/writer" logic in pipe_read/write()).
1056 */
1057 void pipe_wait_readable(struct pipe_inode_info *pipe)
1058 {
1059 pipe_unlock(pipe);
1060 wait_event_interruptible(pipe->rd_wait, pipe_readable(pipe));
1061 pipe_lock(pipe);
1062 }
1063
1064 void pipe_wait_writable(struct pipe_inode_info *pipe)
1065 {
1066 pipe_unlock(pipe);
1067 wait_event_interruptible(pipe->wr_wait, pipe_writable(pipe));
1068 pipe_lock(pipe);
1069 }
1070
1071 /*
1072 * This depends on both the wait (here) and the wakeup (wake_up_partner)
1073 * holding the pipe lock, so "*cnt" is stable and we know a wakeup cannot
1074 * race with the count check and waitqueue prep.
1075 *
1076 * Normally in order to avoid races, you'd do the prepare_to_wait() first,
1077 * then check the condition you're waiting for, and only then sleep. But
1078 * because of the pipe lock, we can check the condition before being on
1079 * the wait queue.
1080 *
1081 * We use the 'rd_wait' waitqueue for pipe partner waiting.
1082 */
1083 static int wait_for_partner(struct pipe_inode_info *pipe, unsigned int *cnt)
1084 {
1085 DEFINE_WAIT(rdwait);
1086 int cur = *cnt;
1087
1088 while (cur == *cnt) {
1089 prepare_to_wait(&pipe->rd_wait, &rdwait, TASK_INTERRUPTIBLE);
1090 pipe_unlock(pipe);
1091 schedule();
1092 finish_wait(&pipe->rd_wait, &rdwait);
1093 pipe_lock(pipe);
1094 if (signal_pending(current))
1095 break;
1096 }
1097 return cur == *cnt ? -ERESTARTSYS : 0;
1098 }
1099
1100 static void wake_up_partner(struct pipe_inode_info *pipe)
1101 {
1102 wake_up_interruptible_all(&pipe->rd_wait);
1103 }
1104
1105 static int fifo_open(struct inode *inode, struct file *filp)
1106 {
1107 struct pipe_inode_info *pipe;
1108 bool is_pipe = inode->i_sb->s_magic == PIPEFS_MAGIC;
1109 int ret;
1110
1111 filp->f_version = 0;
1112
1113 spin_lock(&inode->i_lock);
1114 if (inode->i_pipe) {
1115 pipe = inode->i_pipe;
1116 pipe->files++;
1117 spin_unlock(&inode->i_lock);
1118 } else {
1119 spin_unlock(&inode->i_lock);
1120 pipe = alloc_pipe_info();
1121 if (!pipe)
1122 return -ENOMEM;
1123 pipe->files = 1;
1124 spin_lock(&inode->i_lock);
1125 if (unlikely(inode->i_pipe)) {
1126 inode->i_pipe->files++;
1127 spin_unlock(&inode->i_lock);
1128 free_pipe_info(pipe);
1129 pipe = inode->i_pipe;
1130 } else {
1131 inode->i_pipe = pipe;
1132 spin_unlock(&inode->i_lock);
1133 }
1134 }
1135 filp->private_data = pipe;
1136 /* OK, we have a pipe and it's pinned down */
1137
1138 mutex_lock(&pipe->mutex);
1139
1140 /* We can only do regular read/write on fifos */
1141 stream_open(inode, filp);
1142
1143 switch (filp->f_mode & (FMODE_READ | FMODE_WRITE)) {
1144 case FMODE_READ:
1145 /*
1146 * O_RDONLY
1147 * POSIX.1 says that O_NONBLOCK means return with the FIFO
1148 * opened, even when there is no process writing the FIFO.
1149 */
1150 pipe->r_counter++;
1151 if (pipe->readers++ == 0)
1152 wake_up_partner(pipe);
1153
1154 if (!is_pipe && !pipe->writers) {
1155 if ((filp->f_flags & O_NONBLOCK)) {
1156 /* suppress EPOLLHUP until we have
1157 * seen a writer */
1158 filp->f_version = pipe->w_counter;
1159 } else {
1160 if (wait_for_partner(pipe, &pipe->w_counter))
1161 goto err_rd;
1162 }
1163 }
1164 break;
1165
1166 case FMODE_WRITE:
1167 /*
1168 * O_WRONLY
1169 * POSIX.1 says that O_NONBLOCK means return -1 with
1170 * errno=ENXIO when there is no process reading the FIFO.
1171 */
1172 ret = -ENXIO;
1173 if (!is_pipe && (filp->f_flags & O_NONBLOCK) && !pipe->readers)
1174 goto err;
1175
1176 pipe->w_counter++;
1177 if (!pipe->writers++)
1178 wake_up_partner(pipe);
1179
1180 if (!is_pipe && !pipe->readers) {
1181 if (wait_for_partner(pipe, &pipe->r_counter))
1182 goto err_wr;
1183 }
1184 break;
1185
1186 case FMODE_READ | FMODE_WRITE:
1187 /*
1188 * O_RDWR
1189 * POSIX.1 leaves this case "undefined" when O_NONBLOCK is set.
1190 * This implementation will NEVER block on a O_RDWR open, since
1191 * the process can at least talk to itself.
1192 */
1193
1194 pipe->readers++;
1195 pipe->writers++;
1196 pipe->r_counter++;
1197 pipe->w_counter++;
1198 if (pipe->readers == 1 || pipe->writers == 1)
1199 wake_up_partner(pipe);
1200 break;
1201
1202 default:
1203 ret = -EINVAL;
1204 goto err;
1205 }
1206
1207 /* Ok! */
1208 mutex_unlock(&pipe->mutex);
1209 return 0;
1210
1211 err_rd:
1212 if (!--pipe->readers)
1213 wake_up_interruptible(&pipe->wr_wait);
1214 ret = -ERESTARTSYS;
1215 goto err;
1216
1217 err_wr:
1218 if (!--pipe->writers)
1219 wake_up_interruptible_all(&pipe->rd_wait);
1220 ret = -ERESTARTSYS;
1221 goto err;
1222
1223 err:
1224 mutex_unlock(&pipe->mutex);
1225
1226 put_pipe_info(inode, pipe);
1227 return ret;
1228 }
1229
1230 const struct file_operations pipefifo_fops = {
1231 .open = fifo_open,
1232 .llseek = no_llseek,
1233 .read_iter = pipe_read,
1234 .write_iter = pipe_write,
1235 .poll = pipe_poll,
1236 .unlocked_ioctl = pipe_ioctl,
1237 .release = pipe_release,
1238 .fasync = pipe_fasync,
1239 .splice_write = iter_file_splice_write,
1240 };
1241
1242 /*
1243 * Currently we rely on the pipe array holding a power-of-2 number
1244 * of pages. Returns 0 on error.
1245 */
1246 unsigned int round_pipe_size(unsigned int size)
1247 {
1248 if (size > (1U << 31))
1249 return 0;
1250
1251 /* Minimum pipe size, as required by POSIX */
1252 if (size < PAGE_SIZE)
1253 return PAGE_SIZE;
1254
1255 return roundup_pow_of_two(size);
1256 }
1257
1258 /*
1259 * Resize the pipe ring to a number of slots.
1260 *
1261 * Note the pipe can be reduced in capacity, but only if the current
1262 * occupancy doesn't exceed nr_slots; if it does, EBUSY will be
1263 * returned instead.
1264 */
1265 int pipe_resize_ring(struct pipe_inode_info *pipe, unsigned int nr_slots)
1266 {
1267 struct pipe_buffer *bufs;
1268 unsigned int head, tail, mask, n;
1269
1270 bufs = kcalloc(nr_slots, sizeof(*bufs),
1271 GFP_KERNEL_ACCOUNT | __GFP_NOWARN);
1272 if (unlikely(!bufs))
1273 return -ENOMEM;
1274
1275 spin_lock_irq(&pipe->rd_wait.lock);
1276 mask = pipe->ring_size - 1;
1277 head = pipe->head;
1278 tail = pipe->tail;
1279
1280 n = pipe_occupancy(head, tail);
1281 if (nr_slots < n) {
1282 spin_unlock_irq(&pipe->rd_wait.lock);
1283 kfree(bufs);
1284 return -EBUSY;
1285 }
1286
1287 /*
1288 * The pipe array wraps around, so just start the new one at zero
1289 * and adjust the indices.
1290 */
1291 if (n > 0) {
1292 unsigned int h = head & mask;
1293 unsigned int t = tail & mask;
1294 if (h > t) {
1295 memcpy(bufs, pipe->bufs + t,
1296 n * sizeof(struct pipe_buffer));
1297 } else {
1298 unsigned int tsize = pipe->ring_size - t;
1299 if (h > 0)
1300 memcpy(bufs + tsize, pipe->bufs,
1301 h * sizeof(struct pipe_buffer));
1302 memcpy(bufs, pipe->bufs + t,
1303 tsize * sizeof(struct pipe_buffer));
1304 }
1305 }
1306
1307 head = n;
1308 tail = 0;
1309
1310 kfree(pipe->bufs);
1311 pipe->bufs = bufs;
1312 pipe->ring_size = nr_slots;
1313 if (pipe->max_usage > nr_slots)
1314 pipe->max_usage = nr_slots;
1315 pipe->tail = tail;
1316 pipe->head = head;
1317
1318 if (!pipe_has_watch_queue(pipe)) {
1319 pipe->max_usage = nr_slots;
1320 pipe->nr_accounted = nr_slots;
1321 }
1322
1323 spin_unlock_irq(&pipe->rd_wait.lock);
1324
1325 /* This might have made more room for writers */
1326 wake_up_interruptible(&pipe->wr_wait);
1327 return 0;
1328 }
1329
1330 /*
1331 * Allocate a new array of pipe buffers and copy the info over. Returns the
1332 * pipe size if successful, or return -ERROR on error.
1333 */
1334 static long pipe_set_size(struct pipe_inode_info *pipe, unsigned int arg)
1335 {
1336 unsigned long user_bufs;
1337 unsigned int nr_slots, size;
1338 long ret = 0;
1339
1340 if (pipe_has_watch_queue(pipe))
1341 return -EBUSY;
1342
1343 size = round_pipe_size(arg);
1344 nr_slots = size >> PAGE_SHIFT;
1345
1346 if (!nr_slots)
1347 return -EINVAL;
1348
1349 /*
1350 * If trying to increase the pipe capacity, check that an
1351 * unprivileged user is not trying to exceed various limits
1352 * (soft limit check here, hard limit check just below).
1353 * Decreasing the pipe capacity is always permitted, even
1354 * if the user is currently over a limit.
1355 */
1356 if (nr_slots > pipe->max_usage &&
1357 size > pipe_max_size && !capable(CAP_SYS_RESOURCE))
1358 return -EPERM;
1359
1360 user_bufs = account_pipe_buffers(pipe->user, pipe->nr_accounted, nr_slots);
1361
1362 if (nr_slots > pipe->max_usage &&
1363 (too_many_pipe_buffers_hard(user_bufs) ||
1364 too_many_pipe_buffers_soft(user_bufs)) &&
1365 pipe_is_unprivileged_user()) {
1366 ret = -EPERM;
1367 goto out_revert_acct;
1368 }
1369
1370 ret = pipe_resize_ring(pipe, nr_slots);
1371 if (ret < 0)
1372 goto out_revert_acct;
1373
1374 return pipe->max_usage * PAGE_SIZE;
1375
1376 out_revert_acct:
1377 (void) account_pipe_buffers(pipe->user, nr_slots, pipe->nr_accounted);
1378 return ret;
1379 }
1380
1381 /*
1382 * Note that i_pipe and i_cdev share the same location, so checking ->i_pipe is
1383 * not enough to verify that this is a pipe.
1384 */
1385 struct pipe_inode_info *get_pipe_info(struct file *file, bool for_splice)
1386 {
1387 struct pipe_inode_info *pipe = file->private_data;
1388
1389 if (file->f_op != &pipefifo_fops || !pipe)
1390 return NULL;
1391 if (for_splice && pipe_has_watch_queue(pipe))
1392 return NULL;
1393 return pipe;
1394 }
1395
1396 long pipe_fcntl(struct file *file, unsigned int cmd, unsigned int arg)
1397 {
1398 struct pipe_inode_info *pipe;
1399 long ret;
1400
1401 pipe = get_pipe_info(file, false);
1402 if (!pipe)
1403 return -EBADF;
1404
1405 mutex_lock(&pipe->mutex);
1406
1407 switch (cmd) {
1408 case F_SETPIPE_SZ:
1409 ret = pipe_set_size(pipe, arg);
1410 break;
1411 case F_GETPIPE_SZ:
1412 ret = pipe->max_usage * PAGE_SIZE;
1413 break;
1414 default:
1415 ret = -EINVAL;
1416 break;
1417 }
1418
1419 mutex_unlock(&pipe->mutex);
1420 return ret;
1421 }
1422
1423 static const struct super_operations pipefs_ops = {
1424 .destroy_inode = free_inode_nonrcu,
1425 .statfs = simple_statfs,
1426 };
1427
1428 /*
1429 * pipefs should _never_ be mounted by userland - too much of security hassle,
1430 * no real gain from having the whole whorehouse mounted. So we don't need
1431 * any operations on the root directory. However, we need a non-trivial
1432 * d_name - pipe: will go nicely and kill the special-casing in procfs.
1433 */
1434
1435 static int pipefs_init_fs_context(struct fs_context *fc)
1436 {
1437 struct pseudo_fs_context *ctx = init_pseudo(fc, PIPEFS_MAGIC);
1438 if (!ctx)
1439 return -ENOMEM;
1440 ctx->ops = &pipefs_ops;
1441 ctx->dops = &pipefs_dentry_operations;
1442 return 0;
1443 }
1444
1445 static struct file_system_type pipe_fs_type = {
1446 .name = "pipefs",
1447 .init_fs_context = pipefs_init_fs_context,
1448 .kill_sb = kill_anon_super,
1449 };
1450
1451 #ifdef CONFIG_SYSCTL
1452 static int do_proc_dopipe_max_size_conv(unsigned long *lvalp,
1453 unsigned int *valp,
1454 int write, void *data)
1455 {
1456 if (write) {
1457 unsigned int val;
1458
1459 val = round_pipe_size(*lvalp);
1460 if (val == 0)
1461 return -EINVAL;
1462
1463 *valp = val;
1464 } else {
1465 unsigned int val = *valp;
1466 *lvalp = (unsigned long) val;
1467 }
1468
1469 return 0;
1470 }
1471
1472 static int proc_dopipe_max_size(const struct ctl_table *table, int write,
1473 void *buffer, size_t *lenp, loff_t *ppos)
1474 {
1475 return do_proc_douintvec(table, write, buffer, lenp, ppos,
1476 do_proc_dopipe_max_size_conv, NULL);
1477 }
1478
1479 static struct ctl_table fs_pipe_sysctls[] = {
1480 {
1481 .procname = "pipe-max-size",
1482 .data = &pipe_max_size,
1483 .maxlen = sizeof(pipe_max_size),
1484 .mode = 0644,
1485 .proc_handler = proc_dopipe_max_size,
1486 },
1487 {
1488 .procname = "pipe-user-pages-hard",
1489 .data = &pipe_user_pages_hard,
1490 .maxlen = sizeof(pipe_user_pages_hard),
1491 .mode = 0644,
1492 .proc_handler = proc_doulongvec_minmax,
1493 },
1494 {
1495 .procname = "pipe-user-pages-soft",
1496 .data = &pipe_user_pages_soft,
1497 .maxlen = sizeof(pipe_user_pages_soft),
1498 .mode = 0644,
1499 .proc_handler = proc_doulongvec_minmax,
1500 },
1501 };
1502 #endif
1503
1504 static int __init init_pipe_fs(void)
1505 {
1506 int err = register_filesystem(&pipe_fs_type);
1507
1508 if (!err) {
1509 pipe_mnt = kern_mount(&pipe_fs_type);
1510 if (IS_ERR(pipe_mnt)) {
1511 err = PTR_ERR(pipe_mnt);
1512 unregister_filesystem(&pipe_fs_type);
1513 }
1514 }
1515 #ifdef CONFIG_SYSCTL
1516 register_sysctl_init("fs", fs_pipe_sysctls);
1517 #endif
1518 return err;
1519 }
1520
1521 fs_initcall(init_pipe_fs);
1522
Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.