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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
28#include <linux/uaccess.h>
29#include <asm/ioctls.h>
30
31#include "internal.h"
32
33/*
34 * The max size that a non-root user is allowed to grow the pipe. Can
35 * be set by root in /proc/sys/fs/pipe-max-size
36 */
37unsigned int pipe_max_size = 1048576;
38
39/* Maximum allocatable pages per user. Hard limit is unset by default, soft
40 * matches default values.
41 */
42unsigned long pipe_user_pages_hard;
43unsigned long pipe_user_pages_soft = PIPE_DEF_BUFFERS * INR_OPEN_CUR;
44
45/*
46 * We use a start+len construction, which provides full use of the
47 * allocated memory.
48 * -- Florian Coosmann (FGC)
49 *
50 * Reads with count = 0 should always return 0.
51 * -- Julian Bradfield 1999-06-07.
52 *
53 * FIFOs and Pipes now generate SIGIO for both readers and writers.
54 * -- Jeremy Elson <jelson@circlemud.org> 2001-08-16
55 *
56 * pipe_read & write cleanup
57 * -- Manfred Spraul <manfred@colorfullife.com> 2002-05-09
58 */
59
60static void pipe_lock_nested(struct pipe_inode_info *pipe, int subclass)
61{
62 if (pipe->files)
63 mutex_lock_nested(&pipe->mutex, subclass);
64}
65
66void pipe_lock(struct pipe_inode_info *pipe)
67{
68 /*
69 * pipe_lock() nests non-pipe inode locks (for writing to a file)
70 */
71 pipe_lock_nested(pipe, I_MUTEX_PARENT);
72}
73EXPORT_SYMBOL(pipe_lock);
74
75void pipe_unlock(struct pipe_inode_info *pipe)
76{
77 if (pipe->files)
78 mutex_unlock(&pipe->mutex);
79}
80EXPORT_SYMBOL(pipe_unlock);
81
82static inline void __pipe_lock(struct pipe_inode_info *pipe)
83{
84 mutex_lock_nested(&pipe->mutex, I_MUTEX_PARENT);
85}
86
87static inline void __pipe_unlock(struct pipe_inode_info *pipe)
88{
89 mutex_unlock(&pipe->mutex);
90}
91
92void pipe_double_lock(struct pipe_inode_info *pipe1,
93 struct pipe_inode_info *pipe2)
94{
95 BUG_ON(pipe1 == pipe2);
96
97 if (pipe1 < pipe2) {
98 pipe_lock_nested(pipe1, I_MUTEX_PARENT);
99 pipe_lock_nested(pipe2, I_MUTEX_CHILD);
100 } else {
101 pipe_lock_nested(pipe2, I_MUTEX_PARENT);
102 pipe_lock_nested(pipe1, I_MUTEX_CHILD);
103 }
104}
105
106/* Drop the inode semaphore and wait for a pipe event, atomically */
107void pipe_wait(struct pipe_inode_info *pipe)
108{
109 DEFINE_WAIT(wait);
110
111 /*
112 * Pipes are system-local resources, so sleeping on them
113 * is considered a noninteractive wait:
114 */
115 prepare_to_wait(&pipe->wait, &wait, TASK_INTERRUPTIBLE);
116 pipe_unlock(pipe);
117 schedule();
118 finish_wait(&pipe->wait, &wait);
119 pipe_lock(pipe);
120}
121
122static void anon_pipe_buf_release(struct pipe_inode_info *pipe,
123 struct pipe_buffer *buf)
124{
125 struct page *page = buf->page;
126
127 /*
128 * If nobody else uses this page, and we don't already have a
129 * temporary page, let's keep track of it as a one-deep
130 * allocation cache. (Otherwise just release our reference to it)
131 */
132 if (page_count(page) == 1 && !pipe->tmp_page)
133 pipe->tmp_page = page;
134 else
135 put_page(page);
136}
137
138static int anon_pipe_buf_steal(struct pipe_inode_info *pipe,
139 struct pipe_buffer *buf)
140{
141 struct page *page = buf->page;
142
143 if (page_count(page) == 1) {
144 memcg_kmem_uncharge(page, 0);
145 __SetPageLocked(page);
146 return 0;
147 }
148 return 1;
149}
150
151/**
152 * generic_pipe_buf_steal - attempt to take ownership of a &pipe_buffer
153 * @pipe: the pipe that the buffer belongs to
154 * @buf: the buffer to attempt to steal
155 *
156 * Description:
157 * This function attempts to steal the &struct page attached to
158 * @buf. If successful, this function returns 0 and returns with
159 * the page locked. The caller may then reuse the page for whatever
160 * he wishes; the typical use is insertion into a different file
161 * page cache.
162 */
163int generic_pipe_buf_steal(struct pipe_inode_info *pipe,
164 struct pipe_buffer *buf)
165{
166 struct page *page = buf->page;
167
168 /*
169 * A reference of one is golden, that means that the owner of this
170 * page is the only one holding a reference to it. lock the page
171 * and return OK.
172 */
173 if (page_count(page) == 1) {
174 lock_page(page);
175 return 0;
176 }
177
178 return 1;
179}
180EXPORT_SYMBOL(generic_pipe_buf_steal);
181
182/**
183 * generic_pipe_buf_get - get a reference to a &struct pipe_buffer
184 * @pipe: the pipe that the buffer belongs to
185 * @buf: the buffer to get a reference to
186 *
187 * Description:
188 * This function grabs an extra reference to @buf. It's used in
189 * in the tee() system call, when we duplicate the buffers in one
190 * pipe into another.
191 */
192bool generic_pipe_buf_get(struct pipe_inode_info *pipe, struct pipe_buffer *buf)
193{
194 return try_get_page(buf->page);
195}
196EXPORT_SYMBOL(generic_pipe_buf_get);
197
198/**
199 * generic_pipe_buf_confirm - verify contents of the pipe buffer
200 * @info: the pipe that the buffer belongs to
201 * @buf: the buffer to confirm
202 *
203 * Description:
204 * This function does nothing, because the generic pipe code uses
205 * pages that are always good when inserted into the pipe.
206 */
207int generic_pipe_buf_confirm(struct pipe_inode_info *info,
208 struct pipe_buffer *buf)
209{
210 return 0;
211}
212EXPORT_SYMBOL(generic_pipe_buf_confirm);
213
214/**
215 * generic_pipe_buf_release - put a reference to a &struct pipe_buffer
216 * @pipe: the pipe that the buffer belongs to
217 * @buf: the buffer to put a reference to
218 *
219 * Description:
220 * This function releases a reference to @buf.
221 */
222void generic_pipe_buf_release(struct pipe_inode_info *pipe,
223 struct pipe_buffer *buf)
224{
225 put_page(buf->page);
226}
227EXPORT_SYMBOL(generic_pipe_buf_release);
228
229/* New data written to a pipe may be appended to a buffer with this type. */
230static const struct pipe_buf_operations anon_pipe_buf_ops = {
231 .confirm = generic_pipe_buf_confirm,
232 .release = anon_pipe_buf_release,
233 .steal = anon_pipe_buf_steal,
234 .get = generic_pipe_buf_get,
235};
236
237static const struct pipe_buf_operations anon_pipe_buf_nomerge_ops = {
238 .confirm = generic_pipe_buf_confirm,
239 .release = anon_pipe_buf_release,
240 .steal = anon_pipe_buf_steal,
241 .get = generic_pipe_buf_get,
242};
243
244static const struct pipe_buf_operations packet_pipe_buf_ops = {
245 .confirm = generic_pipe_buf_confirm,
246 .release = anon_pipe_buf_release,
247 .steal = anon_pipe_buf_steal,
248 .get = generic_pipe_buf_get,
249};
250
251/**
252 * pipe_buf_mark_unmergeable - mark a &struct pipe_buffer as unmergeable
253 * @buf: the buffer to mark
254 *
255 * Description:
256 * This function ensures that no future writes will be merged into the
257 * given &struct pipe_buffer. This is necessary when multiple pipe buffers
258 * share the same backing page.
259 */
260void pipe_buf_mark_unmergeable(struct pipe_buffer *buf)
261{
262 if (buf->ops == &anon_pipe_buf_ops)
263 buf->ops = &anon_pipe_buf_nomerge_ops;
264}
265
266static bool pipe_buf_can_merge(struct pipe_buffer *buf)
267{
268 return buf->ops == &anon_pipe_buf_ops;
269}
270
271static ssize_t
272pipe_read(struct kiocb *iocb, struct iov_iter *to)
273{
274 size_t total_len = iov_iter_count(to);
275 struct file *filp = iocb->ki_filp;
276 struct pipe_inode_info *pipe = filp->private_data;
277 int do_wakeup;
278 ssize_t ret;
279
280 /* Null read succeeds. */
281 if (unlikely(total_len == 0))
282 return 0;
283
284 do_wakeup = 0;
285 ret = 0;
286 __pipe_lock(pipe);
287 for (;;) {
288 int bufs = pipe->nrbufs;
289 if (bufs) {
290 int curbuf = pipe->curbuf;
291 struct pipe_buffer *buf = pipe->bufs + curbuf;
292 size_t chars = buf->len;
293 size_t written;
294 int error;
295
296 if (chars > total_len)
297 chars = total_len;
298
299 error = pipe_buf_confirm(pipe, buf);
300 if (error) {
301 if (!ret)
302 ret = error;
303 break;
304 }
305
306 written = copy_page_to_iter(buf->page, buf->offset, chars, to);
307 if (unlikely(written < chars)) {
308 if (!ret)
309 ret = -EFAULT;
310 break;
311 }
312 ret += chars;
313 buf->offset += chars;
314 buf->len -= chars;
315
316 /* Was it a packet buffer? Clean up and exit */
317 if (buf->flags & PIPE_BUF_FLAG_PACKET) {
318 total_len = chars;
319 buf->len = 0;
320 }
321
322 if (!buf->len) {
323 pipe_buf_release(pipe, buf);
324 curbuf = (curbuf + 1) & (pipe->buffers - 1);
325 pipe->curbuf = curbuf;
326 pipe->nrbufs = --bufs;
327 do_wakeup = 1;
328 }
329 total_len -= chars;
330 if (!total_len)
331 break; /* common path: read succeeded */
332 }
333 if (bufs) /* More to do? */
334 continue;
335 if (!pipe->writers)
336 break;
337 if (!pipe->waiting_writers) {
338 /* syscall merging: Usually we must not sleep
339 * if O_NONBLOCK is set, or if we got some data.
340 * But if a writer sleeps in kernel space, then
341 * we can wait for that data without violating POSIX.
342 */
343 if (ret)
344 break;
345 if (filp->f_flags & O_NONBLOCK) {
346 ret = -EAGAIN;
347 break;
348 }
349 }
350 if (signal_pending(current)) {
351 if (!ret)
352 ret = -ERESTARTSYS;
353 break;
354 }
355 if (do_wakeup) {
356 wake_up_interruptible_sync_poll(&pipe->wait, EPOLLOUT | EPOLLWRNORM);
357 kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT);
358 }
359 pipe_wait(pipe);
360 }
361 __pipe_unlock(pipe);
362
363 /* Signal writers asynchronously that there is more room. */
364 if (do_wakeup) {
365 wake_up_interruptible_sync_poll(&pipe->wait, EPOLLOUT | EPOLLWRNORM);
366 kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT);
367 }
368 if (ret > 0)
369 file_accessed(filp);
370 return ret;
371}
372
373static inline int is_packetized(struct file *file)
374{
375 return (file->f_flags & O_DIRECT) != 0;
376}
377
378static ssize_t
379pipe_write(struct kiocb *iocb, struct iov_iter *from)
380{
381 struct file *filp = iocb->ki_filp;
382 struct pipe_inode_info *pipe = filp->private_data;
383 ssize_t ret = 0;
384 int do_wakeup = 0;
385 size_t total_len = iov_iter_count(from);
386 ssize_t chars;
387
388 /* Null write succeeds. */
389 if (unlikely(total_len == 0))
390 return 0;
391
392 __pipe_lock(pipe);
393
394 if (!pipe->readers) {
395 send_sig(SIGPIPE, current, 0);
396 ret = -EPIPE;
397 goto out;
398 }
399
400 /* We try to merge small writes */
401 chars = total_len & (PAGE_SIZE-1); /* size of the last buffer */
402 if (pipe->nrbufs && chars != 0) {
403 int lastbuf = (pipe->curbuf + pipe->nrbufs - 1) &
404 (pipe->buffers - 1);
405 struct pipe_buffer *buf = pipe->bufs + lastbuf;
406 int offset = buf->offset + buf->len;
407
408 if (pipe_buf_can_merge(buf) && offset + chars <= PAGE_SIZE) {
409 ret = pipe_buf_confirm(pipe, buf);
410 if (ret)
411 goto out;
412
413 ret = copy_page_from_iter(buf->page, offset, chars, from);
414 if (unlikely(ret < chars)) {
415 ret = -EFAULT;
416 goto out;
417 }
418 do_wakeup = 1;
419 buf->len += ret;
420 if (!iov_iter_count(from))
421 goto out;
422 }
423 }
424
425 for (;;) {
426 int bufs;
427
428 if (!pipe->readers) {
429 send_sig(SIGPIPE, current, 0);
430 if (!ret)
431 ret = -EPIPE;
432 break;
433 }
434 bufs = pipe->nrbufs;
435 if (bufs < pipe->buffers) {
436 int newbuf = (pipe->curbuf + bufs) & (pipe->buffers-1);
437 struct pipe_buffer *buf = pipe->bufs + newbuf;
438 struct page *page = pipe->tmp_page;
439 int copied;
440
441 if (!page) {
442 page = alloc_page(GFP_HIGHUSER | __GFP_ACCOUNT);
443 if (unlikely(!page)) {
444 ret = ret ? : -ENOMEM;
445 break;
446 }
447 pipe->tmp_page = page;
448 }
449 /* Always wake up, even if the copy fails. Otherwise
450 * we lock up (O_NONBLOCK-)readers that sleep due to
451 * syscall merging.
452 * FIXME! Is this really true?
453 */
454 do_wakeup = 1;
455 copied = copy_page_from_iter(page, 0, PAGE_SIZE, from);
456 if (unlikely(copied < PAGE_SIZE && iov_iter_count(from))) {
457 if (!ret)
458 ret = -EFAULT;
459 break;
460 }
461 ret += copied;
462
463 /* Insert it into the buffer array */
464 buf->page = page;
465 buf->ops = &anon_pipe_buf_ops;
466 buf->offset = 0;
467 buf->len = copied;
468 buf->flags = 0;
469 if (is_packetized(filp)) {
470 buf->ops = &packet_pipe_buf_ops;
471 buf->flags = PIPE_BUF_FLAG_PACKET;
472 }
473 pipe->nrbufs = ++bufs;
474 pipe->tmp_page = NULL;
475
476 if (!iov_iter_count(from))
477 break;
478 }
479 if (bufs < pipe->buffers)
480 continue;
481 if (filp->f_flags & O_NONBLOCK) {
482 if (!ret)
483 ret = -EAGAIN;
484 break;
485 }
486 if (signal_pending(current)) {
487 if (!ret)
488 ret = -ERESTARTSYS;
489 break;
490 }
491 if (do_wakeup) {
492 wake_up_interruptible_sync_poll(&pipe->wait, EPOLLIN | EPOLLRDNORM);
493 kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
494 do_wakeup = 0;
495 }
496 pipe->waiting_writers++;
497 pipe_wait(pipe);
498 pipe->waiting_writers--;
499 }
500out:
501 __pipe_unlock(pipe);
502 if (do_wakeup) {
503 wake_up_interruptible_sync_poll(&pipe->wait, EPOLLIN | EPOLLRDNORM);
504 kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
505 }
506 if (ret > 0 && sb_start_write_trylock(file_inode(filp)->i_sb)) {
507 int err = file_update_time(filp);
508 if (err)
509 ret = err;
510 sb_end_write(file_inode(filp)->i_sb);
511 }
512 return ret;
513}
514
515static long pipe_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
516{
517 struct pipe_inode_info *pipe = filp->private_data;
518 int count, buf, nrbufs;
519
520 switch (cmd) {
521 case FIONREAD:
522 __pipe_lock(pipe);
523 count = 0;
524 buf = pipe->curbuf;
525 nrbufs = pipe->nrbufs;
526 while (--nrbufs >= 0) {
527 count += pipe->bufs[buf].len;
528 buf = (buf+1) & (pipe->buffers - 1);
529 }
530 __pipe_unlock(pipe);
531
532 return put_user(count, (int __user *)arg);
533 default:
534 return -ENOIOCTLCMD;
535 }
536}
537
538/* No kernel lock held - fine */
539static __poll_t
540pipe_poll(struct file *filp, poll_table *wait)
541{
542 __poll_t mask;
543 struct pipe_inode_info *pipe = filp->private_data;
544 int nrbufs;
545
546 poll_wait(filp, &pipe->wait, wait);
547
548 /* Reading only -- no need for acquiring the semaphore. */
549 nrbufs = pipe->nrbufs;
550 mask = 0;
551 if (filp->f_mode & FMODE_READ) {
552 mask = (nrbufs > 0) ? EPOLLIN | EPOLLRDNORM : 0;
553 if (!pipe->writers && filp->f_version != pipe->w_counter)
554 mask |= EPOLLHUP;
555 }
556
557 if (filp->f_mode & FMODE_WRITE) {
558 mask |= (nrbufs < pipe->buffers) ? EPOLLOUT | EPOLLWRNORM : 0;
559 /*
560 * Most Unices do not set EPOLLERR for FIFOs but on Linux they
561 * behave exactly like pipes for poll().
562 */
563 if (!pipe->readers)
564 mask |= EPOLLERR;
565 }
566
567 return mask;
568}
569
570static void put_pipe_info(struct inode *inode, struct pipe_inode_info *pipe)
571{
572 int kill = 0;
573
574 spin_lock(&inode->i_lock);
575 if (!--pipe->files) {
576 inode->i_pipe = NULL;
577 kill = 1;
578 }
579 spin_unlock(&inode->i_lock);
580
581 if (kill)
582 free_pipe_info(pipe);
583}
584
585static int
586pipe_release(struct inode *inode, struct file *file)
587{
588 struct pipe_inode_info *pipe = file->private_data;
589
590 __pipe_lock(pipe);
591 if (file->f_mode & FMODE_READ)
592 pipe->readers--;
593 if (file->f_mode & FMODE_WRITE)
594 pipe->writers--;
595
596 if (pipe->readers || pipe->writers) {
597 wake_up_interruptible_sync_poll(&pipe->wait, EPOLLIN | EPOLLOUT | EPOLLRDNORM | EPOLLWRNORM | EPOLLERR | EPOLLHUP);
598 kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
599 kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT);
600 }
601 __pipe_unlock(pipe);
602
603 put_pipe_info(inode, pipe);
604 return 0;
605}
606
607static int
608pipe_fasync(int fd, struct file *filp, int on)
609{
610 struct pipe_inode_info *pipe = filp->private_data;
611 int retval = 0;
612
613 __pipe_lock(pipe);
614 if (filp->f_mode & FMODE_READ)
615 retval = fasync_helper(fd, filp, on, &pipe->fasync_readers);
616 if ((filp->f_mode & FMODE_WRITE) && retval >= 0) {
617 retval = fasync_helper(fd, filp, on, &pipe->fasync_writers);
618 if (retval < 0 && (filp->f_mode & FMODE_READ))
619 /* this can happen only if on == T */
620 fasync_helper(-1, filp, 0, &pipe->fasync_readers);
621 }
622 __pipe_unlock(pipe);
623 return retval;
624}
625
626static unsigned long account_pipe_buffers(struct user_struct *user,
627 unsigned long old, unsigned long new)
628{
629 return atomic_long_add_return(new - old, &user->pipe_bufs);
630}
631
632static bool too_many_pipe_buffers_soft(unsigned long user_bufs)
633{
634 unsigned long soft_limit = READ_ONCE(pipe_user_pages_soft);
635
636 return soft_limit && user_bufs > soft_limit;
637}
638
639static bool too_many_pipe_buffers_hard(unsigned long user_bufs)
640{
641 unsigned long hard_limit = READ_ONCE(pipe_user_pages_hard);
642
643 return hard_limit && user_bufs > hard_limit;
644}
645
646static bool is_unprivileged_user(void)
647{
648 return !capable(CAP_SYS_RESOURCE) && !capable(CAP_SYS_ADMIN);
649}
650
651struct pipe_inode_info *alloc_pipe_info(void)
652{
653 struct pipe_inode_info *pipe;
654 unsigned long pipe_bufs = PIPE_DEF_BUFFERS;
655 struct user_struct *user = get_current_user();
656 unsigned long user_bufs;
657 unsigned int max_size = READ_ONCE(pipe_max_size);
658
659 pipe = kzalloc(sizeof(struct pipe_inode_info), GFP_KERNEL_ACCOUNT);
660 if (pipe == NULL)
661 goto out_free_uid;
662
663 if (pipe_bufs * PAGE_SIZE > max_size && !capable(CAP_SYS_RESOURCE))
664 pipe_bufs = max_size >> PAGE_SHIFT;
665
666 user_bufs = account_pipe_buffers(user, 0, pipe_bufs);
667
668 if (too_many_pipe_buffers_soft(user_bufs) && is_unprivileged_user()) {
669 user_bufs = account_pipe_buffers(user, pipe_bufs, 1);
670 pipe_bufs = 1;
671 }
672
673 if (too_many_pipe_buffers_hard(user_bufs) && is_unprivileged_user())
674 goto out_revert_acct;
675
676 pipe->bufs = kcalloc(pipe_bufs, sizeof(struct pipe_buffer),
677 GFP_KERNEL_ACCOUNT);
678
679 if (pipe->bufs) {
680 init_waitqueue_head(&pipe->wait);
681 pipe->r_counter = pipe->w_counter = 1;
682 pipe->buffers = pipe_bufs;
683 pipe->user = user;
684 mutex_init(&pipe->mutex);
685 return pipe;
686 }
687
688out_revert_acct:
689 (void) account_pipe_buffers(user, pipe_bufs, 0);
690 kfree(pipe);
691out_free_uid:
692 free_uid(user);
693 return NULL;
694}
695
696void free_pipe_info(struct pipe_inode_info *pipe)
697{
698 int i;
699
700 (void) account_pipe_buffers(pipe->user, pipe->buffers, 0);
701 free_uid(pipe->user);
702 for (i = 0; i < pipe->buffers; i++) {
703 struct pipe_buffer *buf = pipe->bufs + i;
704 if (buf->ops)
705 pipe_buf_release(pipe, buf);
706 }
707 if (pipe->tmp_page)
708 __free_page(pipe->tmp_page);
709 kfree(pipe->bufs);
710 kfree(pipe);
711}
712
713static struct vfsmount *pipe_mnt __read_mostly;
714
715/*
716 * pipefs_dname() is called from d_path().
717 */
718static char *pipefs_dname(struct dentry *dentry, char *buffer, int buflen)
719{
720 return dynamic_dname(dentry, buffer, buflen, "pipe:[%lu]",
721 d_inode(dentry)->i_ino);
722}
723
724static const struct dentry_operations pipefs_dentry_operations = {
725 .d_dname = pipefs_dname,
726};
727
728static struct inode * get_pipe_inode(void)
729{
730 struct inode *inode = new_inode_pseudo(pipe_mnt->mnt_sb);
731 struct pipe_inode_info *pipe;
732
733 if (!inode)
734 goto fail_inode;
735
736 inode->i_ino = get_next_ino();
737
738 pipe = alloc_pipe_info();
739 if (!pipe)
740 goto fail_iput;
741
742 inode->i_pipe = pipe;
743 pipe->files = 2;
744 pipe->readers = pipe->writers = 1;
745 inode->i_fop = &pipefifo_fops;
746
747 /*
748 * Mark the inode dirty from the very beginning,
749 * that way it will never be moved to the dirty
750 * list because "mark_inode_dirty()" will think
751 * that it already _is_ on the dirty list.
752 */
753 inode->i_state = I_DIRTY;
754 inode->i_mode = S_IFIFO | S_IRUSR | S_IWUSR;
755 inode->i_uid = current_fsuid();
756 inode->i_gid = current_fsgid();
757 inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode);
758
759 return inode;
760
761fail_iput:
762 iput(inode);
763
764fail_inode:
765 return NULL;
766}
767
768int create_pipe_files(struct file **res, int flags)
769{
770 struct inode *inode = get_pipe_inode();
771 struct file *f;
772
773 if (!inode)
774 return -ENFILE;
775
776 f = alloc_file_pseudo(inode, pipe_mnt, "",
777 O_WRONLY | (flags & (O_NONBLOCK | O_DIRECT)),
778 &pipefifo_fops);
779 if (IS_ERR(f)) {
780 free_pipe_info(inode->i_pipe);
781 iput(inode);
782 return PTR_ERR(f);
783 }
784
785 f->private_data = inode->i_pipe;
786
787 res[0] = alloc_file_clone(f, O_RDONLY | (flags & O_NONBLOCK),
788 &pipefifo_fops);
789 if (IS_ERR(res[0])) {
790 put_pipe_info(inode, inode->i_pipe);
791 fput(f);
792 return PTR_ERR(res[0]);
793 }
794 res[0]->private_data = inode->i_pipe;
795 res[1] = f;
796 return 0;
797}
798
799static int __do_pipe_flags(int *fd, struct file **files, int flags)
800{
801 int error;
802 int fdw, fdr;
803
804 if (flags & ~(O_CLOEXEC | O_NONBLOCK | O_DIRECT))
805 return -EINVAL;
806
807 error = create_pipe_files(files, flags);
808 if (error)
809 return error;
810
811 error = get_unused_fd_flags(flags);
812 if (error < 0)
813 goto err_read_pipe;
814 fdr = error;
815
816 error = get_unused_fd_flags(flags);
817 if (error < 0)
818 goto err_fdr;
819 fdw = error;
820
821 audit_fd_pair(fdr, fdw);
822 fd[0] = fdr;
823 fd[1] = fdw;
824 return 0;
825
826 err_fdr:
827 put_unused_fd(fdr);
828 err_read_pipe:
829 fput(files[0]);
830 fput(files[1]);
831 return error;
832}
833
834int do_pipe_flags(int *fd, int flags)
835{
836 struct file *files[2];
837 int error = __do_pipe_flags(fd, files, flags);
838 if (!error) {
839 fd_install(fd[0], files[0]);
840 fd_install(fd[1], files[1]);
841 }
842 return error;
843}
844
845/*
846 * sys_pipe() is the normal C calling standard for creating
847 * a pipe. It's not the way Unix traditionally does this, though.
848 */
849static int do_pipe2(int __user *fildes, int flags)
850{
851 struct file *files[2];
852 int fd[2];
853 int error;
854
855 error = __do_pipe_flags(fd, files, flags);
856 if (!error) {
857 if (unlikely(copy_to_user(fildes, fd, sizeof(fd)))) {
858 fput(files[0]);
859 fput(files[1]);
860 put_unused_fd(fd[0]);
861 put_unused_fd(fd[1]);
862 error = -EFAULT;
863 } else {
864 fd_install(fd[0], files[0]);
865 fd_install(fd[1], files[1]);
866 }
867 }
868 return error;
869}
870
871SYSCALL_DEFINE2(pipe2, int __user *, fildes, int, flags)
872{
873 return do_pipe2(fildes, flags);
874}
875
876SYSCALL_DEFINE1(pipe, int __user *, fildes)
877{
878 return do_pipe2(fildes, 0);
879}
880
881static int wait_for_partner(struct pipe_inode_info *pipe, unsigned int *cnt)
882{
883 int cur = *cnt;
884
885 while (cur == *cnt) {
886 pipe_wait(pipe);
887 if (signal_pending(current))
888 break;
889 }
890 return cur == *cnt ? -ERESTARTSYS : 0;
891}
892
893static void wake_up_partner(struct pipe_inode_info *pipe)
894{
895 wake_up_interruptible(&pipe->wait);
896}
897
898static int fifo_open(struct inode *inode, struct file *filp)
899{
900 struct pipe_inode_info *pipe;
901 bool is_pipe = inode->i_sb->s_magic == PIPEFS_MAGIC;
902 int ret;
903
904 filp->f_version = 0;
905
906 spin_lock(&inode->i_lock);
907 if (inode->i_pipe) {
908 pipe = inode->i_pipe;
909 pipe->files++;
910 spin_unlock(&inode->i_lock);
911 } else {
912 spin_unlock(&inode->i_lock);
913 pipe = alloc_pipe_info();
914 if (!pipe)
915 return -ENOMEM;
916 pipe->files = 1;
917 spin_lock(&inode->i_lock);
918 if (unlikely(inode->i_pipe)) {
919 inode->i_pipe->files++;
920 spin_unlock(&inode->i_lock);
921 free_pipe_info(pipe);
922 pipe = inode->i_pipe;
923 } else {
924 inode->i_pipe = pipe;
925 spin_unlock(&inode->i_lock);
926 }
927 }
928 filp->private_data = pipe;
929 /* OK, we have a pipe and it's pinned down */
930
931 __pipe_lock(pipe);
932
933 /* We can only do regular read/write on fifos */
934 filp->f_mode &= (FMODE_READ | FMODE_WRITE);
935
936 switch (filp->f_mode) {
937 case FMODE_READ:
938 /*
939 * O_RDONLY
940 * POSIX.1 says that O_NONBLOCK means return with the FIFO
941 * opened, even when there is no process writing the FIFO.
942 */
943 pipe->r_counter++;
944 if (pipe->readers++ == 0)
945 wake_up_partner(pipe);
946
947 if (!is_pipe && !pipe->writers) {
948 if ((filp->f_flags & O_NONBLOCK)) {
949 /* suppress EPOLLHUP until we have
950 * seen a writer */
951 filp->f_version = pipe->w_counter;
952 } else {
953 if (wait_for_partner(pipe, &pipe->w_counter))
954 goto err_rd;
955 }
956 }
957 break;
958
959 case FMODE_WRITE:
960 /*
961 * O_WRONLY
962 * POSIX.1 says that O_NONBLOCK means return -1 with
963 * errno=ENXIO when there is no process reading the FIFO.
964 */
965 ret = -ENXIO;
966 if (!is_pipe && (filp->f_flags & O_NONBLOCK) && !pipe->readers)
967 goto err;
968
969 pipe->w_counter++;
970 if (!pipe->writers++)
971 wake_up_partner(pipe);
972
973 if (!is_pipe && !pipe->readers) {
974 if (wait_for_partner(pipe, &pipe->r_counter))
975 goto err_wr;
976 }
977 break;
978
979 case FMODE_READ | FMODE_WRITE:
980 /*
981 * O_RDWR
982 * POSIX.1 leaves this case "undefined" when O_NONBLOCK is set.
983 * This implementation will NEVER block on a O_RDWR open, since
984 * the process can at least talk to itself.
985 */
986
987 pipe->readers++;
988 pipe->writers++;
989 pipe->r_counter++;
990 pipe->w_counter++;
991 if (pipe->readers == 1 || pipe->writers == 1)
992 wake_up_partner(pipe);
993 break;
994
995 default:
996 ret = -EINVAL;
997 goto err;
998 }
999
1000 /* Ok! */
1001 __pipe_unlock(pipe);
1002 return 0;
1003
1004err_rd:
1005 if (!--pipe->readers)
1006 wake_up_interruptible(&pipe->wait);
1007 ret = -ERESTARTSYS;
1008 goto err;
1009
1010err_wr:
1011 if (!--pipe->writers)
1012 wake_up_interruptible(&pipe->wait);
1013 ret = -ERESTARTSYS;
1014 goto err;
1015
1016err:
1017 __pipe_unlock(pipe);
1018
1019 put_pipe_info(inode, pipe);
1020 return ret;
1021}
1022
1023const struct file_operations pipefifo_fops = {
1024 .open = fifo_open,
1025 .llseek = no_llseek,
1026 .read_iter = pipe_read,
1027 .write_iter = pipe_write,
1028 .poll = pipe_poll,
1029 .unlocked_ioctl = pipe_ioctl,
1030 .release = pipe_release,
1031 .fasync = pipe_fasync,
1032};
1033
1034/*
1035 * Currently we rely on the pipe array holding a power-of-2 number
1036 * of pages. Returns 0 on error.
1037 */
1038unsigned int round_pipe_size(unsigned long size)
1039{
1040 if (size > (1U << 31))
1041 return 0;
1042
1043 /* Minimum pipe size, as required by POSIX */
1044 if (size < PAGE_SIZE)
1045 return PAGE_SIZE;
1046
1047 return roundup_pow_of_two(size);
1048}
1049
1050/*
1051 * Allocate a new array of pipe buffers and copy the info over. Returns the
1052 * pipe size if successful, or return -ERROR on error.
1053 */
1054static long pipe_set_size(struct pipe_inode_info *pipe, unsigned long arg)
1055{
1056 struct pipe_buffer *bufs;
1057 unsigned int size, nr_pages;
1058 unsigned long user_bufs;
1059 long ret = 0;
1060
1061 size = round_pipe_size(arg);
1062 nr_pages = size >> PAGE_SHIFT;
1063
1064 if (!nr_pages)
1065 return -EINVAL;
1066
1067 /*
1068 * If trying to increase the pipe capacity, check that an
1069 * unprivileged user is not trying to exceed various limits
1070 * (soft limit check here, hard limit check just below).
1071 * Decreasing the pipe capacity is always permitted, even
1072 * if the user is currently over a limit.
1073 */
1074 if (nr_pages > pipe->buffers &&
1075 size > pipe_max_size && !capable(CAP_SYS_RESOURCE))
1076 return -EPERM;
1077
1078 user_bufs = account_pipe_buffers(pipe->user, pipe->buffers, nr_pages);
1079
1080 if (nr_pages > pipe->buffers &&
1081 (too_many_pipe_buffers_hard(user_bufs) ||
1082 too_many_pipe_buffers_soft(user_bufs)) &&
1083 is_unprivileged_user()) {
1084 ret = -EPERM;
1085 goto out_revert_acct;
1086 }
1087
1088 /*
1089 * We can shrink the pipe, if arg >= pipe->nrbufs. Since we don't
1090 * expect a lot of shrink+grow operations, just free and allocate
1091 * again like we would do for growing. If the pipe currently
1092 * contains more buffers than arg, then return busy.
1093 */
1094 if (nr_pages < pipe->nrbufs) {
1095 ret = -EBUSY;
1096 goto out_revert_acct;
1097 }
1098
1099 bufs = kcalloc(nr_pages, sizeof(*bufs),
1100 GFP_KERNEL_ACCOUNT | __GFP_NOWARN);
1101 if (unlikely(!bufs)) {
1102 ret = -ENOMEM;
1103 goto out_revert_acct;
1104 }
1105
1106 /*
1107 * The pipe array wraps around, so just start the new one at zero
1108 * and adjust the indexes.
1109 */
1110 if (pipe->nrbufs) {
1111 unsigned int tail;
1112 unsigned int head;
1113
1114 tail = pipe->curbuf + pipe->nrbufs;
1115 if (tail < pipe->buffers)
1116 tail = 0;
1117 else
1118 tail &= (pipe->buffers - 1);
1119
1120 head = pipe->nrbufs - tail;
1121 if (head)
1122 memcpy(bufs, pipe->bufs + pipe->curbuf, head * sizeof(struct pipe_buffer));
1123 if (tail)
1124 memcpy(bufs + head, pipe->bufs, tail * sizeof(struct pipe_buffer));
1125 }
1126
1127 pipe->curbuf = 0;
1128 kfree(pipe->bufs);
1129 pipe->bufs = bufs;
1130 pipe->buffers = nr_pages;
1131 return nr_pages * PAGE_SIZE;
1132
1133out_revert_acct:
1134 (void) account_pipe_buffers(pipe->user, nr_pages, pipe->buffers);
1135 return ret;
1136}
1137
1138/*
1139 * After the inode slimming patch, i_pipe/i_bdev/i_cdev share the same
1140 * location, so checking ->i_pipe is not enough to verify that this is a
1141 * pipe.
1142 */
1143struct pipe_inode_info *get_pipe_info(struct file *file)
1144{
1145 return file->f_op == &pipefifo_fops ? file->private_data : NULL;
1146}
1147
1148long pipe_fcntl(struct file *file, unsigned int cmd, unsigned long arg)
1149{
1150 struct pipe_inode_info *pipe;
1151 long ret;
1152
1153 pipe = get_pipe_info(file);
1154 if (!pipe)
1155 return -EBADF;
1156
1157 __pipe_lock(pipe);
1158
1159 switch (cmd) {
1160 case F_SETPIPE_SZ:
1161 ret = pipe_set_size(pipe, arg);
1162 break;
1163 case F_GETPIPE_SZ:
1164 ret = pipe->buffers * PAGE_SIZE;
1165 break;
1166 default:
1167 ret = -EINVAL;
1168 break;
1169 }
1170
1171 __pipe_unlock(pipe);
1172 return ret;
1173}
1174
1175static const struct super_operations pipefs_ops = {
1176 .destroy_inode = free_inode_nonrcu,
1177 .statfs = simple_statfs,
1178};
1179
1180/*
1181 * pipefs should _never_ be mounted by userland - too much of security hassle,
1182 * no real gain from having the whole whorehouse mounted. So we don't need
1183 * any operations on the root directory. However, we need a non-trivial
1184 * d_name - pipe: will go nicely and kill the special-casing in procfs.
1185 */
1186
1187static int pipefs_init_fs_context(struct fs_context *fc)
1188{
1189 struct pseudo_fs_context *ctx = init_pseudo(fc, PIPEFS_MAGIC);
1190 if (!ctx)
1191 return -ENOMEM;
1192 ctx->ops = &pipefs_ops;
1193 ctx->dops = &pipefs_dentry_operations;
1194 return 0;
1195}
1196
1197static struct file_system_type pipe_fs_type = {
1198 .name = "pipefs",
1199 .init_fs_context = pipefs_init_fs_context,
1200 .kill_sb = kill_anon_super,
1201};
1202
1203static int __init init_pipe_fs(void)
1204{
1205 int err = register_filesystem(&pipe_fs_type);
1206
1207 if (!err) {
1208 pipe_mnt = kern_mount(&pipe_fs_type);
1209 if (IS_ERR(pipe_mnt)) {
1210 err = PTR_ERR(pipe_mnt);
1211 unregister_filesystem(&pipe_fs_type);
1212 }
1213 }
1214 return err;
1215}
1216
1217fs_initcall(init_pipe_fs);
1/*
2 * linux/fs/pipe.c
3 *
4 * Copyright (C) 1991, 1992, 1999 Linus Torvalds
5 */
6
7#include <linux/mm.h>
8#include <linux/file.h>
9#include <linux/poll.h>
10#include <linux/slab.h>
11#include <linux/module.h>
12#include <linux/init.h>
13#include <linux/fs.h>
14#include <linux/log2.h>
15#include <linux/mount.h>
16#include <linux/magic.h>
17#include <linux/pipe_fs_i.h>
18#include <linux/uio.h>
19#include <linux/highmem.h>
20#include <linux/pagemap.h>
21#include <linux/audit.h>
22#include <linux/syscalls.h>
23#include <linux/fcntl.h>
24#include <linux/aio.h>
25
26#include <asm/uaccess.h>
27#include <asm/ioctls.h>
28
29#include "internal.h"
30
31/*
32 * The max size that a non-root user is allowed to grow the pipe. Can
33 * be set by root in /proc/sys/fs/pipe-max-size
34 */
35unsigned int pipe_max_size = 1048576;
36
37/*
38 * Minimum pipe size, as required by POSIX
39 */
40unsigned int pipe_min_size = PAGE_SIZE;
41
42/*
43 * We use a start+len construction, which provides full use of the
44 * allocated memory.
45 * -- Florian Coosmann (FGC)
46 *
47 * Reads with count = 0 should always return 0.
48 * -- Julian Bradfield 1999-06-07.
49 *
50 * FIFOs and Pipes now generate SIGIO for both readers and writers.
51 * -- Jeremy Elson <jelson@circlemud.org> 2001-08-16
52 *
53 * pipe_read & write cleanup
54 * -- Manfred Spraul <manfred@colorfullife.com> 2002-05-09
55 */
56
57static void pipe_lock_nested(struct pipe_inode_info *pipe, int subclass)
58{
59 if (pipe->files)
60 mutex_lock_nested(&pipe->mutex, subclass);
61}
62
63void pipe_lock(struct pipe_inode_info *pipe)
64{
65 /*
66 * pipe_lock() nests non-pipe inode locks (for writing to a file)
67 */
68 pipe_lock_nested(pipe, I_MUTEX_PARENT);
69}
70EXPORT_SYMBOL(pipe_lock);
71
72void pipe_unlock(struct pipe_inode_info *pipe)
73{
74 if (pipe->files)
75 mutex_unlock(&pipe->mutex);
76}
77EXPORT_SYMBOL(pipe_unlock);
78
79static inline void __pipe_lock(struct pipe_inode_info *pipe)
80{
81 mutex_lock_nested(&pipe->mutex, I_MUTEX_PARENT);
82}
83
84static inline void __pipe_unlock(struct pipe_inode_info *pipe)
85{
86 mutex_unlock(&pipe->mutex);
87}
88
89void pipe_double_lock(struct pipe_inode_info *pipe1,
90 struct pipe_inode_info *pipe2)
91{
92 BUG_ON(pipe1 == pipe2);
93
94 if (pipe1 < pipe2) {
95 pipe_lock_nested(pipe1, I_MUTEX_PARENT);
96 pipe_lock_nested(pipe2, I_MUTEX_CHILD);
97 } else {
98 pipe_lock_nested(pipe2, I_MUTEX_PARENT);
99 pipe_lock_nested(pipe1, I_MUTEX_CHILD);
100 }
101}
102
103/* Drop the inode semaphore and wait for a pipe event, atomically */
104void pipe_wait(struct pipe_inode_info *pipe)
105{
106 DEFINE_WAIT(wait);
107
108 /*
109 * Pipes are system-local resources, so sleeping on them
110 * is considered a noninteractive wait:
111 */
112 prepare_to_wait(&pipe->wait, &wait, TASK_INTERRUPTIBLE);
113 pipe_unlock(pipe);
114 schedule();
115 finish_wait(&pipe->wait, &wait);
116 pipe_lock(pipe);
117}
118
119static int
120pipe_iov_copy_from_user(void *to, struct iovec *iov, unsigned long len,
121 int atomic)
122{
123 unsigned long copy;
124
125 while (len > 0) {
126 while (!iov->iov_len)
127 iov++;
128 copy = min_t(unsigned long, len, iov->iov_len);
129
130 if (atomic) {
131 if (__copy_from_user_inatomic(to, iov->iov_base, copy))
132 return -EFAULT;
133 } else {
134 if (copy_from_user(to, iov->iov_base, copy))
135 return -EFAULT;
136 }
137 to += copy;
138 len -= copy;
139 iov->iov_base += copy;
140 iov->iov_len -= copy;
141 }
142 return 0;
143}
144
145/*
146 * Pre-fault in the user memory, so we can use atomic copies.
147 */
148static void iov_fault_in_pages_read(struct iovec *iov, unsigned long len)
149{
150 while (!iov->iov_len)
151 iov++;
152
153 while (len > 0) {
154 unsigned long this_len;
155
156 this_len = min_t(unsigned long, len, iov->iov_len);
157 fault_in_pages_readable(iov->iov_base, this_len);
158 len -= this_len;
159 iov++;
160 }
161}
162
163static void anon_pipe_buf_release(struct pipe_inode_info *pipe,
164 struct pipe_buffer *buf)
165{
166 struct page *page = buf->page;
167
168 /*
169 * If nobody else uses this page, and we don't already have a
170 * temporary page, let's keep track of it as a one-deep
171 * allocation cache. (Otherwise just release our reference to it)
172 */
173 if (page_count(page) == 1 && !pipe->tmp_page)
174 pipe->tmp_page = page;
175 else
176 page_cache_release(page);
177}
178
179/**
180 * generic_pipe_buf_steal - attempt to take ownership of a &pipe_buffer
181 * @pipe: the pipe that the buffer belongs to
182 * @buf: the buffer to attempt to steal
183 *
184 * Description:
185 * This function attempts to steal the &struct page attached to
186 * @buf. If successful, this function returns 0 and returns with
187 * the page locked. The caller may then reuse the page for whatever
188 * he wishes; the typical use is insertion into a different file
189 * page cache.
190 */
191int generic_pipe_buf_steal(struct pipe_inode_info *pipe,
192 struct pipe_buffer *buf)
193{
194 struct page *page = buf->page;
195
196 /*
197 * A reference of one is golden, that means that the owner of this
198 * page is the only one holding a reference to it. lock the page
199 * and return OK.
200 */
201 if (page_count(page) == 1) {
202 lock_page(page);
203 return 0;
204 }
205
206 return 1;
207}
208EXPORT_SYMBOL(generic_pipe_buf_steal);
209
210/**
211 * generic_pipe_buf_get - get a reference to a &struct pipe_buffer
212 * @pipe: the pipe that the buffer belongs to
213 * @buf: the buffer to get a reference to
214 *
215 * Description:
216 * This function grabs an extra reference to @buf. It's used in
217 * in the tee() system call, when we duplicate the buffers in one
218 * pipe into another.
219 */
220void generic_pipe_buf_get(struct pipe_inode_info *pipe, struct pipe_buffer *buf)
221{
222 page_cache_get(buf->page);
223}
224EXPORT_SYMBOL(generic_pipe_buf_get);
225
226/**
227 * generic_pipe_buf_confirm - verify contents of the pipe buffer
228 * @info: the pipe that the buffer belongs to
229 * @buf: the buffer to confirm
230 *
231 * Description:
232 * This function does nothing, because the generic pipe code uses
233 * pages that are always good when inserted into the pipe.
234 */
235int generic_pipe_buf_confirm(struct pipe_inode_info *info,
236 struct pipe_buffer *buf)
237{
238 return 0;
239}
240EXPORT_SYMBOL(generic_pipe_buf_confirm);
241
242/**
243 * generic_pipe_buf_release - put a reference to a &struct pipe_buffer
244 * @pipe: the pipe that the buffer belongs to
245 * @buf: the buffer to put a reference to
246 *
247 * Description:
248 * This function releases a reference to @buf.
249 */
250void generic_pipe_buf_release(struct pipe_inode_info *pipe,
251 struct pipe_buffer *buf)
252{
253 page_cache_release(buf->page);
254}
255EXPORT_SYMBOL(generic_pipe_buf_release);
256
257static const struct pipe_buf_operations anon_pipe_buf_ops = {
258 .can_merge = 1,
259 .confirm = generic_pipe_buf_confirm,
260 .release = anon_pipe_buf_release,
261 .steal = generic_pipe_buf_steal,
262 .get = generic_pipe_buf_get,
263};
264
265static const struct pipe_buf_operations packet_pipe_buf_ops = {
266 .can_merge = 0,
267 .confirm = generic_pipe_buf_confirm,
268 .release = anon_pipe_buf_release,
269 .steal = generic_pipe_buf_steal,
270 .get = generic_pipe_buf_get,
271};
272
273static ssize_t
274pipe_read(struct kiocb *iocb, const struct iovec *_iov,
275 unsigned long nr_segs, loff_t pos)
276{
277 struct file *filp = iocb->ki_filp;
278 struct pipe_inode_info *pipe = filp->private_data;
279 int do_wakeup;
280 ssize_t ret;
281 struct iovec *iov = (struct iovec *)_iov;
282 size_t total_len;
283 struct iov_iter iter;
284
285 total_len = iov_length(iov, nr_segs);
286 /* Null read succeeds. */
287 if (unlikely(total_len == 0))
288 return 0;
289
290 iov_iter_init(&iter, iov, nr_segs, total_len, 0);
291
292 do_wakeup = 0;
293 ret = 0;
294 __pipe_lock(pipe);
295 for (;;) {
296 int bufs = pipe->nrbufs;
297 if (bufs) {
298 int curbuf = pipe->curbuf;
299 struct pipe_buffer *buf = pipe->bufs + curbuf;
300 const struct pipe_buf_operations *ops = buf->ops;
301 size_t chars = buf->len;
302 size_t written;
303 int error;
304
305 if (chars > total_len)
306 chars = total_len;
307
308 error = ops->confirm(pipe, buf);
309 if (error) {
310 if (!ret)
311 ret = error;
312 break;
313 }
314
315 written = copy_page_to_iter(buf->page, buf->offset, chars, &iter);
316 if (unlikely(written < chars)) {
317 if (!ret)
318 ret = -EFAULT;
319 break;
320 }
321 ret += chars;
322 buf->offset += chars;
323 buf->len -= chars;
324
325 /* Was it a packet buffer? Clean up and exit */
326 if (buf->flags & PIPE_BUF_FLAG_PACKET) {
327 total_len = chars;
328 buf->len = 0;
329 }
330
331 if (!buf->len) {
332 buf->ops = NULL;
333 ops->release(pipe, buf);
334 curbuf = (curbuf + 1) & (pipe->buffers - 1);
335 pipe->curbuf = curbuf;
336 pipe->nrbufs = --bufs;
337 do_wakeup = 1;
338 }
339 total_len -= chars;
340 if (!total_len)
341 break; /* common path: read succeeded */
342 }
343 if (bufs) /* More to do? */
344 continue;
345 if (!pipe->writers)
346 break;
347 if (!pipe->waiting_writers) {
348 /* syscall merging: Usually we must not sleep
349 * if O_NONBLOCK is set, or if we got some data.
350 * But if a writer sleeps in kernel space, then
351 * we can wait for that data without violating POSIX.
352 */
353 if (ret)
354 break;
355 if (filp->f_flags & O_NONBLOCK) {
356 ret = -EAGAIN;
357 break;
358 }
359 }
360 if (signal_pending(current)) {
361 if (!ret)
362 ret = -ERESTARTSYS;
363 break;
364 }
365 if (do_wakeup) {
366 wake_up_interruptible_sync_poll(&pipe->wait, POLLOUT | POLLWRNORM);
367 kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT);
368 }
369 pipe_wait(pipe);
370 }
371 __pipe_unlock(pipe);
372
373 /* Signal writers asynchronously that there is more room. */
374 if (do_wakeup) {
375 wake_up_interruptible_sync_poll(&pipe->wait, POLLOUT | POLLWRNORM);
376 kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT);
377 }
378 if (ret > 0)
379 file_accessed(filp);
380 return ret;
381}
382
383static inline int is_packetized(struct file *file)
384{
385 return (file->f_flags & O_DIRECT) != 0;
386}
387
388static ssize_t
389pipe_write(struct kiocb *iocb, const struct iovec *_iov,
390 unsigned long nr_segs, loff_t ppos)
391{
392 struct file *filp = iocb->ki_filp;
393 struct pipe_inode_info *pipe = filp->private_data;
394 ssize_t ret;
395 int do_wakeup;
396 struct iovec *iov = (struct iovec *)_iov;
397 size_t total_len;
398 ssize_t chars;
399
400 total_len = iov_length(iov, nr_segs);
401 /* Null write succeeds. */
402 if (unlikely(total_len == 0))
403 return 0;
404
405 do_wakeup = 0;
406 ret = 0;
407 __pipe_lock(pipe);
408
409 if (!pipe->readers) {
410 send_sig(SIGPIPE, current, 0);
411 ret = -EPIPE;
412 goto out;
413 }
414
415 /* We try to merge small writes */
416 chars = total_len & (PAGE_SIZE-1); /* size of the last buffer */
417 if (pipe->nrbufs && chars != 0) {
418 int lastbuf = (pipe->curbuf + pipe->nrbufs - 1) &
419 (pipe->buffers - 1);
420 struct pipe_buffer *buf = pipe->bufs + lastbuf;
421 const struct pipe_buf_operations *ops = buf->ops;
422 int offset = buf->offset + buf->len;
423
424 if (ops->can_merge && offset + chars <= PAGE_SIZE) {
425 int error, atomic = 1;
426 void *addr;
427
428 error = ops->confirm(pipe, buf);
429 if (error)
430 goto out;
431
432 iov_fault_in_pages_read(iov, chars);
433redo1:
434 if (atomic)
435 addr = kmap_atomic(buf->page);
436 else
437 addr = kmap(buf->page);
438 error = pipe_iov_copy_from_user(offset + addr, iov,
439 chars, atomic);
440 if (atomic)
441 kunmap_atomic(addr);
442 else
443 kunmap(buf->page);
444 ret = error;
445 do_wakeup = 1;
446 if (error) {
447 if (atomic) {
448 atomic = 0;
449 goto redo1;
450 }
451 goto out;
452 }
453 buf->len += chars;
454 total_len -= chars;
455 ret = chars;
456 if (!total_len)
457 goto out;
458 }
459 }
460
461 for (;;) {
462 int bufs;
463
464 if (!pipe->readers) {
465 send_sig(SIGPIPE, current, 0);
466 if (!ret)
467 ret = -EPIPE;
468 break;
469 }
470 bufs = pipe->nrbufs;
471 if (bufs < pipe->buffers) {
472 int newbuf = (pipe->curbuf + bufs) & (pipe->buffers-1);
473 struct pipe_buffer *buf = pipe->bufs + newbuf;
474 struct page *page = pipe->tmp_page;
475 char *src;
476 int error, atomic = 1;
477
478 if (!page) {
479 page = alloc_page(GFP_HIGHUSER);
480 if (unlikely(!page)) {
481 ret = ret ? : -ENOMEM;
482 break;
483 }
484 pipe->tmp_page = page;
485 }
486 /* Always wake up, even if the copy fails. Otherwise
487 * we lock up (O_NONBLOCK-)readers that sleep due to
488 * syscall merging.
489 * FIXME! Is this really true?
490 */
491 do_wakeup = 1;
492 chars = PAGE_SIZE;
493 if (chars > total_len)
494 chars = total_len;
495
496 iov_fault_in_pages_read(iov, chars);
497redo2:
498 if (atomic)
499 src = kmap_atomic(page);
500 else
501 src = kmap(page);
502
503 error = pipe_iov_copy_from_user(src, iov, chars,
504 atomic);
505 if (atomic)
506 kunmap_atomic(src);
507 else
508 kunmap(page);
509
510 if (unlikely(error)) {
511 if (atomic) {
512 atomic = 0;
513 goto redo2;
514 }
515 if (!ret)
516 ret = error;
517 break;
518 }
519 ret += chars;
520
521 /* Insert it into the buffer array */
522 buf->page = page;
523 buf->ops = &anon_pipe_buf_ops;
524 buf->offset = 0;
525 buf->len = chars;
526 buf->flags = 0;
527 if (is_packetized(filp)) {
528 buf->ops = &packet_pipe_buf_ops;
529 buf->flags = PIPE_BUF_FLAG_PACKET;
530 }
531 pipe->nrbufs = ++bufs;
532 pipe->tmp_page = NULL;
533
534 total_len -= chars;
535 if (!total_len)
536 break;
537 }
538 if (bufs < pipe->buffers)
539 continue;
540 if (filp->f_flags & O_NONBLOCK) {
541 if (!ret)
542 ret = -EAGAIN;
543 break;
544 }
545 if (signal_pending(current)) {
546 if (!ret)
547 ret = -ERESTARTSYS;
548 break;
549 }
550 if (do_wakeup) {
551 wake_up_interruptible_sync_poll(&pipe->wait, POLLIN | POLLRDNORM);
552 kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
553 do_wakeup = 0;
554 }
555 pipe->waiting_writers++;
556 pipe_wait(pipe);
557 pipe->waiting_writers--;
558 }
559out:
560 __pipe_unlock(pipe);
561 if (do_wakeup) {
562 wake_up_interruptible_sync_poll(&pipe->wait, POLLIN | POLLRDNORM);
563 kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
564 }
565 if (ret > 0 && sb_start_write_trylock(file_inode(filp)->i_sb)) {
566 int err = file_update_time(filp);
567 if (err)
568 ret = err;
569 sb_end_write(file_inode(filp)->i_sb);
570 }
571 return ret;
572}
573
574static long pipe_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
575{
576 struct pipe_inode_info *pipe = filp->private_data;
577 int count, buf, nrbufs;
578
579 switch (cmd) {
580 case FIONREAD:
581 __pipe_lock(pipe);
582 count = 0;
583 buf = pipe->curbuf;
584 nrbufs = pipe->nrbufs;
585 while (--nrbufs >= 0) {
586 count += pipe->bufs[buf].len;
587 buf = (buf+1) & (pipe->buffers - 1);
588 }
589 __pipe_unlock(pipe);
590
591 return put_user(count, (int __user *)arg);
592 default:
593 return -ENOIOCTLCMD;
594 }
595}
596
597/* No kernel lock held - fine */
598static unsigned int
599pipe_poll(struct file *filp, poll_table *wait)
600{
601 unsigned int mask;
602 struct pipe_inode_info *pipe = filp->private_data;
603 int nrbufs;
604
605 poll_wait(filp, &pipe->wait, wait);
606
607 /* Reading only -- no need for acquiring the semaphore. */
608 nrbufs = pipe->nrbufs;
609 mask = 0;
610 if (filp->f_mode & FMODE_READ) {
611 mask = (nrbufs > 0) ? POLLIN | POLLRDNORM : 0;
612 if (!pipe->writers && filp->f_version != pipe->w_counter)
613 mask |= POLLHUP;
614 }
615
616 if (filp->f_mode & FMODE_WRITE) {
617 mask |= (nrbufs < pipe->buffers) ? POLLOUT | POLLWRNORM : 0;
618 /*
619 * Most Unices do not set POLLERR for FIFOs but on Linux they
620 * behave exactly like pipes for poll().
621 */
622 if (!pipe->readers)
623 mask |= POLLERR;
624 }
625
626 return mask;
627}
628
629static void put_pipe_info(struct inode *inode, struct pipe_inode_info *pipe)
630{
631 int kill = 0;
632
633 spin_lock(&inode->i_lock);
634 if (!--pipe->files) {
635 inode->i_pipe = NULL;
636 kill = 1;
637 }
638 spin_unlock(&inode->i_lock);
639
640 if (kill)
641 free_pipe_info(pipe);
642}
643
644static int
645pipe_release(struct inode *inode, struct file *file)
646{
647 struct pipe_inode_info *pipe = file->private_data;
648
649 __pipe_lock(pipe);
650 if (file->f_mode & FMODE_READ)
651 pipe->readers--;
652 if (file->f_mode & FMODE_WRITE)
653 pipe->writers--;
654
655 if (pipe->readers || pipe->writers) {
656 wake_up_interruptible_sync_poll(&pipe->wait, POLLIN | POLLOUT | POLLRDNORM | POLLWRNORM | POLLERR | POLLHUP);
657 kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
658 kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT);
659 }
660 __pipe_unlock(pipe);
661
662 put_pipe_info(inode, pipe);
663 return 0;
664}
665
666static int
667pipe_fasync(int fd, struct file *filp, int on)
668{
669 struct pipe_inode_info *pipe = filp->private_data;
670 int retval = 0;
671
672 __pipe_lock(pipe);
673 if (filp->f_mode & FMODE_READ)
674 retval = fasync_helper(fd, filp, on, &pipe->fasync_readers);
675 if ((filp->f_mode & FMODE_WRITE) && retval >= 0) {
676 retval = fasync_helper(fd, filp, on, &pipe->fasync_writers);
677 if (retval < 0 && (filp->f_mode & FMODE_READ))
678 /* this can happen only if on == T */
679 fasync_helper(-1, filp, 0, &pipe->fasync_readers);
680 }
681 __pipe_unlock(pipe);
682 return retval;
683}
684
685struct pipe_inode_info *alloc_pipe_info(void)
686{
687 struct pipe_inode_info *pipe;
688
689 pipe = kzalloc(sizeof(struct pipe_inode_info), GFP_KERNEL);
690 if (pipe) {
691 pipe->bufs = kzalloc(sizeof(struct pipe_buffer) * PIPE_DEF_BUFFERS, GFP_KERNEL);
692 if (pipe->bufs) {
693 init_waitqueue_head(&pipe->wait);
694 pipe->r_counter = pipe->w_counter = 1;
695 pipe->buffers = PIPE_DEF_BUFFERS;
696 mutex_init(&pipe->mutex);
697 return pipe;
698 }
699 kfree(pipe);
700 }
701
702 return NULL;
703}
704
705void free_pipe_info(struct pipe_inode_info *pipe)
706{
707 int i;
708
709 for (i = 0; i < pipe->buffers; i++) {
710 struct pipe_buffer *buf = pipe->bufs + i;
711 if (buf->ops)
712 buf->ops->release(pipe, buf);
713 }
714 if (pipe->tmp_page)
715 __free_page(pipe->tmp_page);
716 kfree(pipe->bufs);
717 kfree(pipe);
718}
719
720static struct vfsmount *pipe_mnt __read_mostly;
721
722/*
723 * pipefs_dname() is called from d_path().
724 */
725static char *pipefs_dname(struct dentry *dentry, char *buffer, int buflen)
726{
727 return dynamic_dname(dentry, buffer, buflen, "pipe:[%lu]",
728 dentry->d_inode->i_ino);
729}
730
731static const struct dentry_operations pipefs_dentry_operations = {
732 .d_dname = pipefs_dname,
733};
734
735static struct inode * get_pipe_inode(void)
736{
737 struct inode *inode = new_inode_pseudo(pipe_mnt->mnt_sb);
738 struct pipe_inode_info *pipe;
739
740 if (!inode)
741 goto fail_inode;
742
743 inode->i_ino = get_next_ino();
744
745 pipe = alloc_pipe_info();
746 if (!pipe)
747 goto fail_iput;
748
749 inode->i_pipe = pipe;
750 pipe->files = 2;
751 pipe->readers = pipe->writers = 1;
752 inode->i_fop = &pipefifo_fops;
753
754 /*
755 * Mark the inode dirty from the very beginning,
756 * that way it will never be moved to the dirty
757 * list because "mark_inode_dirty()" will think
758 * that it already _is_ on the dirty list.
759 */
760 inode->i_state = I_DIRTY;
761 inode->i_mode = S_IFIFO | S_IRUSR | S_IWUSR;
762 inode->i_uid = current_fsuid();
763 inode->i_gid = current_fsgid();
764 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
765
766 return inode;
767
768fail_iput:
769 iput(inode);
770
771fail_inode:
772 return NULL;
773}
774
775int create_pipe_files(struct file **res, int flags)
776{
777 int err;
778 struct inode *inode = get_pipe_inode();
779 struct file *f;
780 struct path path;
781 static struct qstr name = { .name = "" };
782
783 if (!inode)
784 return -ENFILE;
785
786 err = -ENOMEM;
787 path.dentry = d_alloc_pseudo(pipe_mnt->mnt_sb, &name);
788 if (!path.dentry)
789 goto err_inode;
790 path.mnt = mntget(pipe_mnt);
791
792 d_instantiate(path.dentry, inode);
793
794 err = -ENFILE;
795 f = alloc_file(&path, FMODE_WRITE, &pipefifo_fops);
796 if (IS_ERR(f))
797 goto err_dentry;
798
799 f->f_flags = O_WRONLY | (flags & (O_NONBLOCK | O_DIRECT));
800 f->private_data = inode->i_pipe;
801
802 res[0] = alloc_file(&path, FMODE_READ, &pipefifo_fops);
803 if (IS_ERR(res[0]))
804 goto err_file;
805
806 path_get(&path);
807 res[0]->private_data = inode->i_pipe;
808 res[0]->f_flags = O_RDONLY | (flags & O_NONBLOCK);
809 res[1] = f;
810 return 0;
811
812err_file:
813 put_filp(f);
814err_dentry:
815 free_pipe_info(inode->i_pipe);
816 path_put(&path);
817 return err;
818
819err_inode:
820 free_pipe_info(inode->i_pipe);
821 iput(inode);
822 return err;
823}
824
825static int __do_pipe_flags(int *fd, struct file **files, int flags)
826{
827 int error;
828 int fdw, fdr;
829
830 if (flags & ~(O_CLOEXEC | O_NONBLOCK | O_DIRECT))
831 return -EINVAL;
832
833 error = create_pipe_files(files, flags);
834 if (error)
835 return error;
836
837 error = get_unused_fd_flags(flags);
838 if (error < 0)
839 goto err_read_pipe;
840 fdr = error;
841
842 error = get_unused_fd_flags(flags);
843 if (error < 0)
844 goto err_fdr;
845 fdw = error;
846
847 audit_fd_pair(fdr, fdw);
848 fd[0] = fdr;
849 fd[1] = fdw;
850 return 0;
851
852 err_fdr:
853 put_unused_fd(fdr);
854 err_read_pipe:
855 fput(files[0]);
856 fput(files[1]);
857 return error;
858}
859
860int do_pipe_flags(int *fd, int flags)
861{
862 struct file *files[2];
863 int error = __do_pipe_flags(fd, files, flags);
864 if (!error) {
865 fd_install(fd[0], files[0]);
866 fd_install(fd[1], files[1]);
867 }
868 return error;
869}
870
871/*
872 * sys_pipe() is the normal C calling standard for creating
873 * a pipe. It's not the way Unix traditionally does this, though.
874 */
875SYSCALL_DEFINE2(pipe2, int __user *, fildes, int, flags)
876{
877 struct file *files[2];
878 int fd[2];
879 int error;
880
881 error = __do_pipe_flags(fd, files, flags);
882 if (!error) {
883 if (unlikely(copy_to_user(fildes, fd, sizeof(fd)))) {
884 fput(files[0]);
885 fput(files[1]);
886 put_unused_fd(fd[0]);
887 put_unused_fd(fd[1]);
888 error = -EFAULT;
889 } else {
890 fd_install(fd[0], files[0]);
891 fd_install(fd[1], files[1]);
892 }
893 }
894 return error;
895}
896
897SYSCALL_DEFINE1(pipe, int __user *, fildes)
898{
899 return sys_pipe2(fildes, 0);
900}
901
902static int wait_for_partner(struct pipe_inode_info *pipe, unsigned int *cnt)
903{
904 int cur = *cnt;
905
906 while (cur == *cnt) {
907 pipe_wait(pipe);
908 if (signal_pending(current))
909 break;
910 }
911 return cur == *cnt ? -ERESTARTSYS : 0;
912}
913
914static void wake_up_partner(struct pipe_inode_info *pipe)
915{
916 wake_up_interruptible(&pipe->wait);
917}
918
919static int fifo_open(struct inode *inode, struct file *filp)
920{
921 struct pipe_inode_info *pipe;
922 bool is_pipe = inode->i_sb->s_magic == PIPEFS_MAGIC;
923 int ret;
924
925 filp->f_version = 0;
926
927 spin_lock(&inode->i_lock);
928 if (inode->i_pipe) {
929 pipe = inode->i_pipe;
930 pipe->files++;
931 spin_unlock(&inode->i_lock);
932 } else {
933 spin_unlock(&inode->i_lock);
934 pipe = alloc_pipe_info();
935 if (!pipe)
936 return -ENOMEM;
937 pipe->files = 1;
938 spin_lock(&inode->i_lock);
939 if (unlikely(inode->i_pipe)) {
940 inode->i_pipe->files++;
941 spin_unlock(&inode->i_lock);
942 free_pipe_info(pipe);
943 pipe = inode->i_pipe;
944 } else {
945 inode->i_pipe = pipe;
946 spin_unlock(&inode->i_lock);
947 }
948 }
949 filp->private_data = pipe;
950 /* OK, we have a pipe and it's pinned down */
951
952 __pipe_lock(pipe);
953
954 /* We can only do regular read/write on fifos */
955 filp->f_mode &= (FMODE_READ | FMODE_WRITE);
956
957 switch (filp->f_mode) {
958 case FMODE_READ:
959 /*
960 * O_RDONLY
961 * POSIX.1 says that O_NONBLOCK means return with the FIFO
962 * opened, even when there is no process writing the FIFO.
963 */
964 pipe->r_counter++;
965 if (pipe->readers++ == 0)
966 wake_up_partner(pipe);
967
968 if (!is_pipe && !pipe->writers) {
969 if ((filp->f_flags & O_NONBLOCK)) {
970 /* suppress POLLHUP until we have
971 * seen a writer */
972 filp->f_version = pipe->w_counter;
973 } else {
974 if (wait_for_partner(pipe, &pipe->w_counter))
975 goto err_rd;
976 }
977 }
978 break;
979
980 case FMODE_WRITE:
981 /*
982 * O_WRONLY
983 * POSIX.1 says that O_NONBLOCK means return -1 with
984 * errno=ENXIO when there is no process reading the FIFO.
985 */
986 ret = -ENXIO;
987 if (!is_pipe && (filp->f_flags & O_NONBLOCK) && !pipe->readers)
988 goto err;
989
990 pipe->w_counter++;
991 if (!pipe->writers++)
992 wake_up_partner(pipe);
993
994 if (!is_pipe && !pipe->readers) {
995 if (wait_for_partner(pipe, &pipe->r_counter))
996 goto err_wr;
997 }
998 break;
999
1000 case FMODE_READ | FMODE_WRITE:
1001 /*
1002 * O_RDWR
1003 * POSIX.1 leaves this case "undefined" when O_NONBLOCK is set.
1004 * This implementation will NEVER block on a O_RDWR open, since
1005 * the process can at least talk to itself.
1006 */
1007
1008 pipe->readers++;
1009 pipe->writers++;
1010 pipe->r_counter++;
1011 pipe->w_counter++;
1012 if (pipe->readers == 1 || pipe->writers == 1)
1013 wake_up_partner(pipe);
1014 break;
1015
1016 default:
1017 ret = -EINVAL;
1018 goto err;
1019 }
1020
1021 /* Ok! */
1022 __pipe_unlock(pipe);
1023 return 0;
1024
1025err_rd:
1026 if (!--pipe->readers)
1027 wake_up_interruptible(&pipe->wait);
1028 ret = -ERESTARTSYS;
1029 goto err;
1030
1031err_wr:
1032 if (!--pipe->writers)
1033 wake_up_interruptible(&pipe->wait);
1034 ret = -ERESTARTSYS;
1035 goto err;
1036
1037err:
1038 __pipe_unlock(pipe);
1039
1040 put_pipe_info(inode, pipe);
1041 return ret;
1042}
1043
1044const struct file_operations pipefifo_fops = {
1045 .open = fifo_open,
1046 .llseek = no_llseek,
1047 .read = do_sync_read,
1048 .aio_read = pipe_read,
1049 .write = do_sync_write,
1050 .aio_write = pipe_write,
1051 .poll = pipe_poll,
1052 .unlocked_ioctl = pipe_ioctl,
1053 .release = pipe_release,
1054 .fasync = pipe_fasync,
1055};
1056
1057/*
1058 * Allocate a new array of pipe buffers and copy the info over. Returns the
1059 * pipe size if successful, or return -ERROR on error.
1060 */
1061static long pipe_set_size(struct pipe_inode_info *pipe, unsigned long nr_pages)
1062{
1063 struct pipe_buffer *bufs;
1064
1065 /*
1066 * We can shrink the pipe, if arg >= pipe->nrbufs. Since we don't
1067 * expect a lot of shrink+grow operations, just free and allocate
1068 * again like we would do for growing. If the pipe currently
1069 * contains more buffers than arg, then return busy.
1070 */
1071 if (nr_pages < pipe->nrbufs)
1072 return -EBUSY;
1073
1074 bufs = kcalloc(nr_pages, sizeof(*bufs), GFP_KERNEL | __GFP_NOWARN);
1075 if (unlikely(!bufs))
1076 return -ENOMEM;
1077
1078 /*
1079 * The pipe array wraps around, so just start the new one at zero
1080 * and adjust the indexes.
1081 */
1082 if (pipe->nrbufs) {
1083 unsigned int tail;
1084 unsigned int head;
1085
1086 tail = pipe->curbuf + pipe->nrbufs;
1087 if (tail < pipe->buffers)
1088 tail = 0;
1089 else
1090 tail &= (pipe->buffers - 1);
1091
1092 head = pipe->nrbufs - tail;
1093 if (head)
1094 memcpy(bufs, pipe->bufs + pipe->curbuf, head * sizeof(struct pipe_buffer));
1095 if (tail)
1096 memcpy(bufs + head, pipe->bufs, tail * sizeof(struct pipe_buffer));
1097 }
1098
1099 pipe->curbuf = 0;
1100 kfree(pipe->bufs);
1101 pipe->bufs = bufs;
1102 pipe->buffers = nr_pages;
1103 return nr_pages * PAGE_SIZE;
1104}
1105
1106/*
1107 * Currently we rely on the pipe array holding a power-of-2 number
1108 * of pages.
1109 */
1110static inline unsigned int round_pipe_size(unsigned int size)
1111{
1112 unsigned long nr_pages;
1113
1114 nr_pages = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
1115 return roundup_pow_of_two(nr_pages) << PAGE_SHIFT;
1116}
1117
1118/*
1119 * This should work even if CONFIG_PROC_FS isn't set, as proc_dointvec_minmax
1120 * will return an error.
1121 */
1122int pipe_proc_fn(struct ctl_table *table, int write, void __user *buf,
1123 size_t *lenp, loff_t *ppos)
1124{
1125 int ret;
1126
1127 ret = proc_dointvec_minmax(table, write, buf, lenp, ppos);
1128 if (ret < 0 || !write)
1129 return ret;
1130
1131 pipe_max_size = round_pipe_size(pipe_max_size);
1132 return ret;
1133}
1134
1135/*
1136 * After the inode slimming patch, i_pipe/i_bdev/i_cdev share the same
1137 * location, so checking ->i_pipe is not enough to verify that this is a
1138 * pipe.
1139 */
1140struct pipe_inode_info *get_pipe_info(struct file *file)
1141{
1142 return file->f_op == &pipefifo_fops ? file->private_data : NULL;
1143}
1144
1145long pipe_fcntl(struct file *file, unsigned int cmd, unsigned long arg)
1146{
1147 struct pipe_inode_info *pipe;
1148 long ret;
1149
1150 pipe = get_pipe_info(file);
1151 if (!pipe)
1152 return -EBADF;
1153
1154 __pipe_lock(pipe);
1155
1156 switch (cmd) {
1157 case F_SETPIPE_SZ: {
1158 unsigned int size, nr_pages;
1159
1160 size = round_pipe_size(arg);
1161 nr_pages = size >> PAGE_SHIFT;
1162
1163 ret = -EINVAL;
1164 if (!nr_pages)
1165 goto out;
1166
1167 if (!capable(CAP_SYS_RESOURCE) && size > pipe_max_size) {
1168 ret = -EPERM;
1169 goto out;
1170 }
1171 ret = pipe_set_size(pipe, nr_pages);
1172 break;
1173 }
1174 case F_GETPIPE_SZ:
1175 ret = pipe->buffers * PAGE_SIZE;
1176 break;
1177 default:
1178 ret = -EINVAL;
1179 break;
1180 }
1181
1182out:
1183 __pipe_unlock(pipe);
1184 return ret;
1185}
1186
1187static const struct super_operations pipefs_ops = {
1188 .destroy_inode = free_inode_nonrcu,
1189 .statfs = simple_statfs,
1190};
1191
1192/*
1193 * pipefs should _never_ be mounted by userland - too much of security hassle,
1194 * no real gain from having the whole whorehouse mounted. So we don't need
1195 * any operations on the root directory. However, we need a non-trivial
1196 * d_name - pipe: will go nicely and kill the special-casing in procfs.
1197 */
1198static struct dentry *pipefs_mount(struct file_system_type *fs_type,
1199 int flags, const char *dev_name, void *data)
1200{
1201 return mount_pseudo(fs_type, "pipe:", &pipefs_ops,
1202 &pipefs_dentry_operations, PIPEFS_MAGIC);
1203}
1204
1205static struct file_system_type pipe_fs_type = {
1206 .name = "pipefs",
1207 .mount = pipefs_mount,
1208 .kill_sb = kill_anon_super,
1209};
1210
1211static int __init init_pipe_fs(void)
1212{
1213 int err = register_filesystem(&pipe_fs_type);
1214
1215 if (!err) {
1216 pipe_mnt = kern_mount(&pipe_fs_type);
1217 if (IS_ERR(pipe_mnt)) {
1218 err = PTR_ERR(pipe_mnt);
1219 unregister_filesystem(&pipe_fs_type);
1220 }
1221 }
1222 return err;
1223}
1224
1225fs_initcall(init_pipe_fs);