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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/pipe_fs_i.h>
17#include <linux/uio.h>
18#include <linux/highmem.h>
19#include <linux/pagemap.h>
20#include <linux/audit.h>
21#include <linux/syscalls.h>
22#include <linux/fcntl.h>
23
24#include <asm/uaccess.h>
25#include <asm/ioctls.h>
26
27/*
28 * The max size that a non-root user is allowed to grow the pipe. Can
29 * be set by root in /proc/sys/fs/pipe-max-size
30 */
31unsigned int pipe_max_size = 1048576;
32
33/*
34 * Minimum pipe size, as required by POSIX
35 */
36unsigned int pipe_min_size = PAGE_SIZE;
37
38/*
39 * We use a start+len construction, which provides full use of the
40 * allocated memory.
41 * -- Florian Coosmann (FGC)
42 *
43 * Reads with count = 0 should always return 0.
44 * -- Julian Bradfield 1999-06-07.
45 *
46 * FIFOs and Pipes now generate SIGIO for both readers and writers.
47 * -- Jeremy Elson <jelson@circlemud.org> 2001-08-16
48 *
49 * pipe_read & write cleanup
50 * -- Manfred Spraul <manfred@colorfullife.com> 2002-05-09
51 */
52
53static void pipe_lock_nested(struct pipe_inode_info *pipe, int subclass)
54{
55 if (pipe->inode)
56 mutex_lock_nested(&pipe->inode->i_mutex, subclass);
57}
58
59void pipe_lock(struct pipe_inode_info *pipe)
60{
61 /*
62 * pipe_lock() nests non-pipe inode locks (for writing to a file)
63 */
64 pipe_lock_nested(pipe, I_MUTEX_PARENT);
65}
66EXPORT_SYMBOL(pipe_lock);
67
68void pipe_unlock(struct pipe_inode_info *pipe)
69{
70 if (pipe->inode)
71 mutex_unlock(&pipe->inode->i_mutex);
72}
73EXPORT_SYMBOL(pipe_unlock);
74
75void pipe_double_lock(struct pipe_inode_info *pipe1,
76 struct pipe_inode_info *pipe2)
77{
78 BUG_ON(pipe1 == pipe2);
79
80 if (pipe1 < pipe2) {
81 pipe_lock_nested(pipe1, I_MUTEX_PARENT);
82 pipe_lock_nested(pipe2, I_MUTEX_CHILD);
83 } else {
84 pipe_lock_nested(pipe2, I_MUTEX_PARENT);
85 pipe_lock_nested(pipe1, I_MUTEX_CHILD);
86 }
87}
88
89/* Drop the inode semaphore and wait for a pipe event, atomically */
90void pipe_wait(struct pipe_inode_info *pipe)
91{
92 DEFINE_WAIT(wait);
93
94 /*
95 * Pipes are system-local resources, so sleeping on them
96 * is considered a noninteractive wait:
97 */
98 prepare_to_wait(&pipe->wait, &wait, TASK_INTERRUPTIBLE);
99 pipe_unlock(pipe);
100 schedule();
101 finish_wait(&pipe->wait, &wait);
102 pipe_lock(pipe);
103}
104
105static int
106pipe_iov_copy_from_user(void *to, struct iovec *iov, unsigned long len,
107 int atomic)
108{
109 unsigned long copy;
110
111 while (len > 0) {
112 while (!iov->iov_len)
113 iov++;
114 copy = min_t(unsigned long, len, iov->iov_len);
115
116 if (atomic) {
117 if (__copy_from_user_inatomic(to, iov->iov_base, copy))
118 return -EFAULT;
119 } else {
120 if (copy_from_user(to, iov->iov_base, copy))
121 return -EFAULT;
122 }
123 to += copy;
124 len -= copy;
125 iov->iov_base += copy;
126 iov->iov_len -= copy;
127 }
128 return 0;
129}
130
131static int
132pipe_iov_copy_to_user(struct iovec *iov, const void *from, unsigned long len,
133 int atomic)
134{
135 unsigned long copy;
136
137 while (len > 0) {
138 while (!iov->iov_len)
139 iov++;
140 copy = min_t(unsigned long, len, iov->iov_len);
141
142 if (atomic) {
143 if (__copy_to_user_inatomic(iov->iov_base, from, copy))
144 return -EFAULT;
145 } else {
146 if (copy_to_user(iov->iov_base, from, copy))
147 return -EFAULT;
148 }
149 from += copy;
150 len -= copy;
151 iov->iov_base += copy;
152 iov->iov_len -= copy;
153 }
154 return 0;
155}
156
157/*
158 * Attempt to pre-fault in the user memory, so we can use atomic copies.
159 * Returns the number of bytes not faulted in.
160 */
161static int iov_fault_in_pages_write(struct iovec *iov, unsigned long len)
162{
163 while (!iov->iov_len)
164 iov++;
165
166 while (len > 0) {
167 unsigned long this_len;
168
169 this_len = min_t(unsigned long, len, iov->iov_len);
170 if (fault_in_pages_writeable(iov->iov_base, this_len))
171 break;
172
173 len -= this_len;
174 iov++;
175 }
176
177 return len;
178}
179
180/*
181 * Pre-fault in the user memory, so we can use atomic copies.
182 */
183static void iov_fault_in_pages_read(struct iovec *iov, unsigned long len)
184{
185 while (!iov->iov_len)
186 iov++;
187
188 while (len > 0) {
189 unsigned long this_len;
190
191 this_len = min_t(unsigned long, len, iov->iov_len);
192 fault_in_pages_readable(iov->iov_base, this_len);
193 len -= this_len;
194 iov++;
195 }
196}
197
198static void anon_pipe_buf_release(struct pipe_inode_info *pipe,
199 struct pipe_buffer *buf)
200{
201 struct page *page = buf->page;
202
203 /*
204 * If nobody else uses this page, and we don't already have a
205 * temporary page, let's keep track of it as a one-deep
206 * allocation cache. (Otherwise just release our reference to it)
207 */
208 if (page_count(page) == 1 && !pipe->tmp_page)
209 pipe->tmp_page = page;
210 else
211 page_cache_release(page);
212}
213
214/**
215 * generic_pipe_buf_map - virtually map a pipe buffer
216 * @pipe: the pipe that the buffer belongs to
217 * @buf: the buffer that should be mapped
218 * @atomic: whether to use an atomic map
219 *
220 * Description:
221 * This function returns a kernel virtual address mapping for the
222 * pipe_buffer passed in @buf. If @atomic is set, an atomic map is provided
223 * and the caller has to be careful not to fault before calling
224 * the unmap function.
225 *
226 * Note that this function occupies KM_USER0 if @atomic != 0.
227 */
228void *generic_pipe_buf_map(struct pipe_inode_info *pipe,
229 struct pipe_buffer *buf, int atomic)
230{
231 if (atomic) {
232 buf->flags |= PIPE_BUF_FLAG_ATOMIC;
233 return kmap_atomic(buf->page, KM_USER0);
234 }
235
236 return kmap(buf->page);
237}
238EXPORT_SYMBOL(generic_pipe_buf_map);
239
240/**
241 * generic_pipe_buf_unmap - unmap a previously mapped pipe buffer
242 * @pipe: the pipe that the buffer belongs to
243 * @buf: the buffer that should be unmapped
244 * @map_data: the data that the mapping function returned
245 *
246 * Description:
247 * This function undoes the mapping that ->map() provided.
248 */
249void generic_pipe_buf_unmap(struct pipe_inode_info *pipe,
250 struct pipe_buffer *buf, void *map_data)
251{
252 if (buf->flags & PIPE_BUF_FLAG_ATOMIC) {
253 buf->flags &= ~PIPE_BUF_FLAG_ATOMIC;
254 kunmap_atomic(map_data, KM_USER0);
255 } else
256 kunmap(buf->page);
257}
258EXPORT_SYMBOL(generic_pipe_buf_unmap);
259
260/**
261 * generic_pipe_buf_steal - attempt to take ownership of a &pipe_buffer
262 * @pipe: the pipe that the buffer belongs to
263 * @buf: the buffer to attempt to steal
264 *
265 * Description:
266 * This function attempts to steal the &struct page attached to
267 * @buf. If successful, this function returns 0 and returns with
268 * the page locked. The caller may then reuse the page for whatever
269 * he wishes; the typical use is insertion into a different file
270 * page cache.
271 */
272int generic_pipe_buf_steal(struct pipe_inode_info *pipe,
273 struct pipe_buffer *buf)
274{
275 struct page *page = buf->page;
276
277 /*
278 * A reference of one is golden, that means that the owner of this
279 * page is the only one holding a reference to it. lock the page
280 * and return OK.
281 */
282 if (page_count(page) == 1) {
283 lock_page(page);
284 return 0;
285 }
286
287 return 1;
288}
289EXPORT_SYMBOL(generic_pipe_buf_steal);
290
291/**
292 * generic_pipe_buf_get - get a reference to a &struct pipe_buffer
293 * @pipe: the pipe that the buffer belongs to
294 * @buf: the buffer to get a reference to
295 *
296 * Description:
297 * This function grabs an extra reference to @buf. It's used in
298 * in the tee() system call, when we duplicate the buffers in one
299 * pipe into another.
300 */
301void generic_pipe_buf_get(struct pipe_inode_info *pipe, struct pipe_buffer *buf)
302{
303 page_cache_get(buf->page);
304}
305EXPORT_SYMBOL(generic_pipe_buf_get);
306
307/**
308 * generic_pipe_buf_confirm - verify contents of the pipe buffer
309 * @info: the pipe that the buffer belongs to
310 * @buf: the buffer to confirm
311 *
312 * Description:
313 * This function does nothing, because the generic pipe code uses
314 * pages that are always good when inserted into the pipe.
315 */
316int generic_pipe_buf_confirm(struct pipe_inode_info *info,
317 struct pipe_buffer *buf)
318{
319 return 0;
320}
321EXPORT_SYMBOL(generic_pipe_buf_confirm);
322
323/**
324 * generic_pipe_buf_release - put a reference to a &struct pipe_buffer
325 * @pipe: the pipe that the buffer belongs to
326 * @buf: the buffer to put a reference to
327 *
328 * Description:
329 * This function releases a reference to @buf.
330 */
331void generic_pipe_buf_release(struct pipe_inode_info *pipe,
332 struct pipe_buffer *buf)
333{
334 page_cache_release(buf->page);
335}
336EXPORT_SYMBOL(generic_pipe_buf_release);
337
338static const struct pipe_buf_operations anon_pipe_buf_ops = {
339 .can_merge = 1,
340 .map = generic_pipe_buf_map,
341 .unmap = generic_pipe_buf_unmap,
342 .confirm = generic_pipe_buf_confirm,
343 .release = anon_pipe_buf_release,
344 .steal = generic_pipe_buf_steal,
345 .get = generic_pipe_buf_get,
346};
347
348static ssize_t
349pipe_read(struct kiocb *iocb, const struct iovec *_iov,
350 unsigned long nr_segs, loff_t pos)
351{
352 struct file *filp = iocb->ki_filp;
353 struct inode *inode = filp->f_path.dentry->d_inode;
354 struct pipe_inode_info *pipe;
355 int do_wakeup;
356 ssize_t ret;
357 struct iovec *iov = (struct iovec *)_iov;
358 size_t total_len;
359
360 total_len = iov_length(iov, nr_segs);
361 /* Null read succeeds. */
362 if (unlikely(total_len == 0))
363 return 0;
364
365 do_wakeup = 0;
366 ret = 0;
367 mutex_lock(&inode->i_mutex);
368 pipe = inode->i_pipe;
369 for (;;) {
370 int bufs = pipe->nrbufs;
371 if (bufs) {
372 int curbuf = pipe->curbuf;
373 struct pipe_buffer *buf = pipe->bufs + curbuf;
374 const struct pipe_buf_operations *ops = buf->ops;
375 void *addr;
376 size_t chars = buf->len;
377 int error, atomic;
378
379 if (chars > total_len)
380 chars = total_len;
381
382 error = ops->confirm(pipe, buf);
383 if (error) {
384 if (!ret)
385 ret = error;
386 break;
387 }
388
389 atomic = !iov_fault_in_pages_write(iov, chars);
390redo:
391 addr = ops->map(pipe, buf, atomic);
392 error = pipe_iov_copy_to_user(iov, addr + buf->offset, chars, atomic);
393 ops->unmap(pipe, buf, addr);
394 if (unlikely(error)) {
395 /*
396 * Just retry with the slow path if we failed.
397 */
398 if (atomic) {
399 atomic = 0;
400 goto redo;
401 }
402 if (!ret)
403 ret = error;
404 break;
405 }
406 ret += chars;
407 buf->offset += chars;
408 buf->len -= chars;
409 if (!buf->len) {
410 buf->ops = NULL;
411 ops->release(pipe, buf);
412 curbuf = (curbuf + 1) & (pipe->buffers - 1);
413 pipe->curbuf = curbuf;
414 pipe->nrbufs = --bufs;
415 do_wakeup = 1;
416 }
417 total_len -= chars;
418 if (!total_len)
419 break; /* common path: read succeeded */
420 }
421 if (bufs) /* More to do? */
422 continue;
423 if (!pipe->writers)
424 break;
425 if (!pipe->waiting_writers) {
426 /* syscall merging: Usually we must not sleep
427 * if O_NONBLOCK is set, or if we got some data.
428 * But if a writer sleeps in kernel space, then
429 * we can wait for that data without violating POSIX.
430 */
431 if (ret)
432 break;
433 if (filp->f_flags & O_NONBLOCK) {
434 ret = -EAGAIN;
435 break;
436 }
437 }
438 if (signal_pending(current)) {
439 if (!ret)
440 ret = -ERESTARTSYS;
441 break;
442 }
443 if (do_wakeup) {
444 wake_up_interruptible_sync_poll(&pipe->wait, POLLOUT | POLLWRNORM);
445 kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT);
446 }
447 pipe_wait(pipe);
448 }
449 mutex_unlock(&inode->i_mutex);
450
451 /* Signal writers asynchronously that there is more room. */
452 if (do_wakeup) {
453 wake_up_interruptible_sync_poll(&pipe->wait, POLLOUT | POLLWRNORM);
454 kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT);
455 }
456 if (ret > 0)
457 file_accessed(filp);
458 return ret;
459}
460
461static ssize_t
462pipe_write(struct kiocb *iocb, const struct iovec *_iov,
463 unsigned long nr_segs, loff_t ppos)
464{
465 struct file *filp = iocb->ki_filp;
466 struct inode *inode = filp->f_path.dentry->d_inode;
467 struct pipe_inode_info *pipe;
468 ssize_t ret;
469 int do_wakeup;
470 struct iovec *iov = (struct iovec *)_iov;
471 size_t total_len;
472 ssize_t chars;
473
474 total_len = iov_length(iov, nr_segs);
475 /* Null write succeeds. */
476 if (unlikely(total_len == 0))
477 return 0;
478
479 do_wakeup = 0;
480 ret = 0;
481 mutex_lock(&inode->i_mutex);
482 pipe = inode->i_pipe;
483
484 if (!pipe->readers) {
485 send_sig(SIGPIPE, current, 0);
486 ret = -EPIPE;
487 goto out;
488 }
489
490 /* We try to merge small writes */
491 chars = total_len & (PAGE_SIZE-1); /* size of the last buffer */
492 if (pipe->nrbufs && chars != 0) {
493 int lastbuf = (pipe->curbuf + pipe->nrbufs - 1) &
494 (pipe->buffers - 1);
495 struct pipe_buffer *buf = pipe->bufs + lastbuf;
496 const struct pipe_buf_operations *ops = buf->ops;
497 int offset = buf->offset + buf->len;
498
499 if (ops->can_merge && offset + chars <= PAGE_SIZE) {
500 int error, atomic = 1;
501 void *addr;
502
503 error = ops->confirm(pipe, buf);
504 if (error)
505 goto out;
506
507 iov_fault_in_pages_read(iov, chars);
508redo1:
509 addr = ops->map(pipe, buf, atomic);
510 error = pipe_iov_copy_from_user(offset + addr, iov,
511 chars, atomic);
512 ops->unmap(pipe, buf, addr);
513 ret = error;
514 do_wakeup = 1;
515 if (error) {
516 if (atomic) {
517 atomic = 0;
518 goto redo1;
519 }
520 goto out;
521 }
522 buf->len += chars;
523 total_len -= chars;
524 ret = chars;
525 if (!total_len)
526 goto out;
527 }
528 }
529
530 for (;;) {
531 int bufs;
532
533 if (!pipe->readers) {
534 send_sig(SIGPIPE, current, 0);
535 if (!ret)
536 ret = -EPIPE;
537 break;
538 }
539 bufs = pipe->nrbufs;
540 if (bufs < pipe->buffers) {
541 int newbuf = (pipe->curbuf + bufs) & (pipe->buffers-1);
542 struct pipe_buffer *buf = pipe->bufs + newbuf;
543 struct page *page = pipe->tmp_page;
544 char *src;
545 int error, atomic = 1;
546
547 if (!page) {
548 page = alloc_page(GFP_HIGHUSER);
549 if (unlikely(!page)) {
550 ret = ret ? : -ENOMEM;
551 break;
552 }
553 pipe->tmp_page = page;
554 }
555 /* Always wake up, even if the copy fails. Otherwise
556 * we lock up (O_NONBLOCK-)readers that sleep due to
557 * syscall merging.
558 * FIXME! Is this really true?
559 */
560 do_wakeup = 1;
561 chars = PAGE_SIZE;
562 if (chars > total_len)
563 chars = total_len;
564
565 iov_fault_in_pages_read(iov, chars);
566redo2:
567 if (atomic)
568 src = kmap_atomic(page, KM_USER0);
569 else
570 src = kmap(page);
571
572 error = pipe_iov_copy_from_user(src, iov, chars,
573 atomic);
574 if (atomic)
575 kunmap_atomic(src, KM_USER0);
576 else
577 kunmap(page);
578
579 if (unlikely(error)) {
580 if (atomic) {
581 atomic = 0;
582 goto redo2;
583 }
584 if (!ret)
585 ret = error;
586 break;
587 }
588 ret += chars;
589
590 /* Insert it into the buffer array */
591 buf->page = page;
592 buf->ops = &anon_pipe_buf_ops;
593 buf->offset = 0;
594 buf->len = chars;
595 pipe->nrbufs = ++bufs;
596 pipe->tmp_page = NULL;
597
598 total_len -= chars;
599 if (!total_len)
600 break;
601 }
602 if (bufs < pipe->buffers)
603 continue;
604 if (filp->f_flags & O_NONBLOCK) {
605 if (!ret)
606 ret = -EAGAIN;
607 break;
608 }
609 if (signal_pending(current)) {
610 if (!ret)
611 ret = -ERESTARTSYS;
612 break;
613 }
614 if (do_wakeup) {
615 wake_up_interruptible_sync_poll(&pipe->wait, POLLIN | POLLRDNORM);
616 kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
617 do_wakeup = 0;
618 }
619 pipe->waiting_writers++;
620 pipe_wait(pipe);
621 pipe->waiting_writers--;
622 }
623out:
624 mutex_unlock(&inode->i_mutex);
625 if (do_wakeup) {
626 wake_up_interruptible_sync_poll(&pipe->wait, POLLIN | POLLRDNORM);
627 kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
628 }
629 if (ret > 0)
630 file_update_time(filp);
631 return ret;
632}
633
634static ssize_t
635bad_pipe_r(struct file *filp, char __user *buf, size_t count, loff_t *ppos)
636{
637 return -EBADF;
638}
639
640static ssize_t
641bad_pipe_w(struct file *filp, const char __user *buf, size_t count,
642 loff_t *ppos)
643{
644 return -EBADF;
645}
646
647static long pipe_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
648{
649 struct inode *inode = filp->f_path.dentry->d_inode;
650 struct pipe_inode_info *pipe;
651 int count, buf, nrbufs;
652
653 switch (cmd) {
654 case FIONREAD:
655 mutex_lock(&inode->i_mutex);
656 pipe = inode->i_pipe;
657 count = 0;
658 buf = pipe->curbuf;
659 nrbufs = pipe->nrbufs;
660 while (--nrbufs >= 0) {
661 count += pipe->bufs[buf].len;
662 buf = (buf+1) & (pipe->buffers - 1);
663 }
664 mutex_unlock(&inode->i_mutex);
665
666 return put_user(count, (int __user *)arg);
667 default:
668 return -EINVAL;
669 }
670}
671
672/* No kernel lock held - fine */
673static unsigned int
674pipe_poll(struct file *filp, poll_table *wait)
675{
676 unsigned int mask;
677 struct inode *inode = filp->f_path.dentry->d_inode;
678 struct pipe_inode_info *pipe = inode->i_pipe;
679 int nrbufs;
680
681 poll_wait(filp, &pipe->wait, wait);
682
683 /* Reading only -- no need for acquiring the semaphore. */
684 nrbufs = pipe->nrbufs;
685 mask = 0;
686 if (filp->f_mode & FMODE_READ) {
687 mask = (nrbufs > 0) ? POLLIN | POLLRDNORM : 0;
688 if (!pipe->writers && filp->f_version != pipe->w_counter)
689 mask |= POLLHUP;
690 }
691
692 if (filp->f_mode & FMODE_WRITE) {
693 mask |= (nrbufs < pipe->buffers) ? POLLOUT | POLLWRNORM : 0;
694 /*
695 * Most Unices do not set POLLERR for FIFOs but on Linux they
696 * behave exactly like pipes for poll().
697 */
698 if (!pipe->readers)
699 mask |= POLLERR;
700 }
701
702 return mask;
703}
704
705static int
706pipe_release(struct inode *inode, int decr, int decw)
707{
708 struct pipe_inode_info *pipe;
709
710 mutex_lock(&inode->i_mutex);
711 pipe = inode->i_pipe;
712 pipe->readers -= decr;
713 pipe->writers -= decw;
714
715 if (!pipe->readers && !pipe->writers) {
716 free_pipe_info(inode);
717 } else {
718 wake_up_interruptible_sync_poll(&pipe->wait, POLLIN | POLLOUT | POLLRDNORM | POLLWRNORM | POLLERR | POLLHUP);
719 kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
720 kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT);
721 }
722 mutex_unlock(&inode->i_mutex);
723
724 return 0;
725}
726
727static int
728pipe_read_fasync(int fd, struct file *filp, int on)
729{
730 struct inode *inode = filp->f_path.dentry->d_inode;
731 int retval;
732
733 mutex_lock(&inode->i_mutex);
734 retval = fasync_helper(fd, filp, on, &inode->i_pipe->fasync_readers);
735 mutex_unlock(&inode->i_mutex);
736
737 return retval;
738}
739
740
741static int
742pipe_write_fasync(int fd, struct file *filp, int on)
743{
744 struct inode *inode = filp->f_path.dentry->d_inode;
745 int retval;
746
747 mutex_lock(&inode->i_mutex);
748 retval = fasync_helper(fd, filp, on, &inode->i_pipe->fasync_writers);
749 mutex_unlock(&inode->i_mutex);
750
751 return retval;
752}
753
754
755static int
756pipe_rdwr_fasync(int fd, struct file *filp, int on)
757{
758 struct inode *inode = filp->f_path.dentry->d_inode;
759 struct pipe_inode_info *pipe = inode->i_pipe;
760 int retval;
761
762 mutex_lock(&inode->i_mutex);
763 retval = fasync_helper(fd, filp, on, &pipe->fasync_readers);
764 if (retval >= 0) {
765 retval = fasync_helper(fd, filp, on, &pipe->fasync_writers);
766 if (retval < 0) /* this can happen only if on == T */
767 fasync_helper(-1, filp, 0, &pipe->fasync_readers);
768 }
769 mutex_unlock(&inode->i_mutex);
770 return retval;
771}
772
773
774static int
775pipe_read_release(struct inode *inode, struct file *filp)
776{
777 return pipe_release(inode, 1, 0);
778}
779
780static int
781pipe_write_release(struct inode *inode, struct file *filp)
782{
783 return pipe_release(inode, 0, 1);
784}
785
786static int
787pipe_rdwr_release(struct inode *inode, struct file *filp)
788{
789 int decr, decw;
790
791 decr = (filp->f_mode & FMODE_READ) != 0;
792 decw = (filp->f_mode & FMODE_WRITE) != 0;
793 return pipe_release(inode, decr, decw);
794}
795
796static int
797pipe_read_open(struct inode *inode, struct file *filp)
798{
799 int ret = -ENOENT;
800
801 mutex_lock(&inode->i_mutex);
802
803 if (inode->i_pipe) {
804 ret = 0;
805 inode->i_pipe->readers++;
806 }
807
808 mutex_unlock(&inode->i_mutex);
809
810 return ret;
811}
812
813static int
814pipe_write_open(struct inode *inode, struct file *filp)
815{
816 int ret = -ENOENT;
817
818 mutex_lock(&inode->i_mutex);
819
820 if (inode->i_pipe) {
821 ret = 0;
822 inode->i_pipe->writers++;
823 }
824
825 mutex_unlock(&inode->i_mutex);
826
827 return ret;
828}
829
830static int
831pipe_rdwr_open(struct inode *inode, struct file *filp)
832{
833 int ret = -ENOENT;
834
835 mutex_lock(&inode->i_mutex);
836
837 if (inode->i_pipe) {
838 ret = 0;
839 if (filp->f_mode & FMODE_READ)
840 inode->i_pipe->readers++;
841 if (filp->f_mode & FMODE_WRITE)
842 inode->i_pipe->writers++;
843 }
844
845 mutex_unlock(&inode->i_mutex);
846
847 return ret;
848}
849
850/*
851 * The file_operations structs are not static because they
852 * are also used in linux/fs/fifo.c to do operations on FIFOs.
853 *
854 * Pipes reuse fifos' file_operations structs.
855 */
856const struct file_operations read_pipefifo_fops = {
857 .llseek = no_llseek,
858 .read = do_sync_read,
859 .aio_read = pipe_read,
860 .write = bad_pipe_w,
861 .poll = pipe_poll,
862 .unlocked_ioctl = pipe_ioctl,
863 .open = pipe_read_open,
864 .release = pipe_read_release,
865 .fasync = pipe_read_fasync,
866};
867
868const struct file_operations write_pipefifo_fops = {
869 .llseek = no_llseek,
870 .read = bad_pipe_r,
871 .write = do_sync_write,
872 .aio_write = pipe_write,
873 .poll = pipe_poll,
874 .unlocked_ioctl = pipe_ioctl,
875 .open = pipe_write_open,
876 .release = pipe_write_release,
877 .fasync = pipe_write_fasync,
878};
879
880const struct file_operations rdwr_pipefifo_fops = {
881 .llseek = no_llseek,
882 .read = do_sync_read,
883 .aio_read = pipe_read,
884 .write = do_sync_write,
885 .aio_write = pipe_write,
886 .poll = pipe_poll,
887 .unlocked_ioctl = pipe_ioctl,
888 .open = pipe_rdwr_open,
889 .release = pipe_rdwr_release,
890 .fasync = pipe_rdwr_fasync,
891};
892
893struct pipe_inode_info * alloc_pipe_info(struct inode *inode)
894{
895 struct pipe_inode_info *pipe;
896
897 pipe = kzalloc(sizeof(struct pipe_inode_info), GFP_KERNEL);
898 if (pipe) {
899 pipe->bufs = kzalloc(sizeof(struct pipe_buffer) * PIPE_DEF_BUFFERS, GFP_KERNEL);
900 if (pipe->bufs) {
901 init_waitqueue_head(&pipe->wait);
902 pipe->r_counter = pipe->w_counter = 1;
903 pipe->inode = inode;
904 pipe->buffers = PIPE_DEF_BUFFERS;
905 return pipe;
906 }
907 kfree(pipe);
908 }
909
910 return NULL;
911}
912
913void __free_pipe_info(struct pipe_inode_info *pipe)
914{
915 int i;
916
917 for (i = 0; i < pipe->buffers; i++) {
918 struct pipe_buffer *buf = pipe->bufs + i;
919 if (buf->ops)
920 buf->ops->release(pipe, buf);
921 }
922 if (pipe->tmp_page)
923 __free_page(pipe->tmp_page);
924 kfree(pipe->bufs);
925 kfree(pipe);
926}
927
928void free_pipe_info(struct inode *inode)
929{
930 __free_pipe_info(inode->i_pipe);
931 inode->i_pipe = NULL;
932}
933
934static struct vfsmount *pipe_mnt __read_mostly;
935
936/*
937 * pipefs_dname() is called from d_path().
938 */
939static char *pipefs_dname(struct dentry *dentry, char *buffer, int buflen)
940{
941 return dynamic_dname(dentry, buffer, buflen, "pipe:[%lu]",
942 dentry->d_inode->i_ino);
943}
944
945static const struct dentry_operations pipefs_dentry_operations = {
946 .d_dname = pipefs_dname,
947};
948
949static struct inode * get_pipe_inode(void)
950{
951 struct inode *inode = new_inode_pseudo(pipe_mnt->mnt_sb);
952 struct pipe_inode_info *pipe;
953
954 if (!inode)
955 goto fail_inode;
956
957 inode->i_ino = get_next_ino();
958
959 pipe = alloc_pipe_info(inode);
960 if (!pipe)
961 goto fail_iput;
962 inode->i_pipe = pipe;
963
964 pipe->readers = pipe->writers = 1;
965 inode->i_fop = &rdwr_pipefifo_fops;
966
967 /*
968 * Mark the inode dirty from the very beginning,
969 * that way it will never be moved to the dirty
970 * list because "mark_inode_dirty()" will think
971 * that it already _is_ on the dirty list.
972 */
973 inode->i_state = I_DIRTY;
974 inode->i_mode = S_IFIFO | S_IRUSR | S_IWUSR;
975 inode->i_uid = current_fsuid();
976 inode->i_gid = current_fsgid();
977 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
978
979 return inode;
980
981fail_iput:
982 iput(inode);
983
984fail_inode:
985 return NULL;
986}
987
988struct file *create_write_pipe(int flags)
989{
990 int err;
991 struct inode *inode;
992 struct file *f;
993 struct path path;
994 struct qstr name = { .name = "" };
995
996 err = -ENFILE;
997 inode = get_pipe_inode();
998 if (!inode)
999 goto err;
1000
1001 err = -ENOMEM;
1002 path.dentry = d_alloc_pseudo(pipe_mnt->mnt_sb, &name);
1003 if (!path.dentry)
1004 goto err_inode;
1005 path.mnt = mntget(pipe_mnt);
1006
1007 d_instantiate(path.dentry, inode);
1008
1009 err = -ENFILE;
1010 f = alloc_file(&path, FMODE_WRITE, &write_pipefifo_fops);
1011 if (!f)
1012 goto err_dentry;
1013 f->f_mapping = inode->i_mapping;
1014
1015 f->f_flags = O_WRONLY | (flags & O_NONBLOCK);
1016 f->f_version = 0;
1017
1018 return f;
1019
1020 err_dentry:
1021 free_pipe_info(inode);
1022 path_put(&path);
1023 return ERR_PTR(err);
1024
1025 err_inode:
1026 free_pipe_info(inode);
1027 iput(inode);
1028 err:
1029 return ERR_PTR(err);
1030}
1031
1032void free_write_pipe(struct file *f)
1033{
1034 free_pipe_info(f->f_dentry->d_inode);
1035 path_put(&f->f_path);
1036 put_filp(f);
1037}
1038
1039struct file *create_read_pipe(struct file *wrf, int flags)
1040{
1041 /* Grab pipe from the writer */
1042 struct file *f = alloc_file(&wrf->f_path, FMODE_READ,
1043 &read_pipefifo_fops);
1044 if (!f)
1045 return ERR_PTR(-ENFILE);
1046
1047 path_get(&wrf->f_path);
1048 f->f_flags = O_RDONLY | (flags & O_NONBLOCK);
1049
1050 return f;
1051}
1052
1053int do_pipe_flags(int *fd, int flags)
1054{
1055 struct file *fw, *fr;
1056 int error;
1057 int fdw, fdr;
1058
1059 if (flags & ~(O_CLOEXEC | O_NONBLOCK))
1060 return -EINVAL;
1061
1062 fw = create_write_pipe(flags);
1063 if (IS_ERR(fw))
1064 return PTR_ERR(fw);
1065 fr = create_read_pipe(fw, flags);
1066 error = PTR_ERR(fr);
1067 if (IS_ERR(fr))
1068 goto err_write_pipe;
1069
1070 error = get_unused_fd_flags(flags);
1071 if (error < 0)
1072 goto err_read_pipe;
1073 fdr = error;
1074
1075 error = get_unused_fd_flags(flags);
1076 if (error < 0)
1077 goto err_fdr;
1078 fdw = error;
1079
1080 audit_fd_pair(fdr, fdw);
1081 fd_install(fdr, fr);
1082 fd_install(fdw, fw);
1083 fd[0] = fdr;
1084 fd[1] = fdw;
1085
1086 return 0;
1087
1088 err_fdr:
1089 put_unused_fd(fdr);
1090 err_read_pipe:
1091 path_put(&fr->f_path);
1092 put_filp(fr);
1093 err_write_pipe:
1094 free_write_pipe(fw);
1095 return error;
1096}
1097
1098/*
1099 * sys_pipe() is the normal C calling standard for creating
1100 * a pipe. It's not the way Unix traditionally does this, though.
1101 */
1102SYSCALL_DEFINE2(pipe2, int __user *, fildes, int, flags)
1103{
1104 int fd[2];
1105 int error;
1106
1107 error = do_pipe_flags(fd, flags);
1108 if (!error) {
1109 if (copy_to_user(fildes, fd, sizeof(fd))) {
1110 sys_close(fd[0]);
1111 sys_close(fd[1]);
1112 error = -EFAULT;
1113 }
1114 }
1115 return error;
1116}
1117
1118SYSCALL_DEFINE1(pipe, int __user *, fildes)
1119{
1120 return sys_pipe2(fildes, 0);
1121}
1122
1123/*
1124 * Allocate a new array of pipe buffers and copy the info over. Returns the
1125 * pipe size if successful, or return -ERROR on error.
1126 */
1127static long pipe_set_size(struct pipe_inode_info *pipe, unsigned long nr_pages)
1128{
1129 struct pipe_buffer *bufs;
1130
1131 /*
1132 * We can shrink the pipe, if arg >= pipe->nrbufs. Since we don't
1133 * expect a lot of shrink+grow operations, just free and allocate
1134 * again like we would do for growing. If the pipe currently
1135 * contains more buffers than arg, then return busy.
1136 */
1137 if (nr_pages < pipe->nrbufs)
1138 return -EBUSY;
1139
1140 bufs = kcalloc(nr_pages, sizeof(struct pipe_buffer), GFP_KERNEL);
1141 if (unlikely(!bufs))
1142 return -ENOMEM;
1143
1144 /*
1145 * The pipe array wraps around, so just start the new one at zero
1146 * and adjust the indexes.
1147 */
1148 if (pipe->nrbufs) {
1149 unsigned int tail;
1150 unsigned int head;
1151
1152 tail = pipe->curbuf + pipe->nrbufs;
1153 if (tail < pipe->buffers)
1154 tail = 0;
1155 else
1156 tail &= (pipe->buffers - 1);
1157
1158 head = pipe->nrbufs - tail;
1159 if (head)
1160 memcpy(bufs, pipe->bufs + pipe->curbuf, head * sizeof(struct pipe_buffer));
1161 if (tail)
1162 memcpy(bufs + head, pipe->bufs, tail * sizeof(struct pipe_buffer));
1163 }
1164
1165 pipe->curbuf = 0;
1166 kfree(pipe->bufs);
1167 pipe->bufs = bufs;
1168 pipe->buffers = nr_pages;
1169 return nr_pages * PAGE_SIZE;
1170}
1171
1172/*
1173 * Currently we rely on the pipe array holding a power-of-2 number
1174 * of pages.
1175 */
1176static inline unsigned int round_pipe_size(unsigned int size)
1177{
1178 unsigned long nr_pages;
1179
1180 nr_pages = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
1181 return roundup_pow_of_two(nr_pages) << PAGE_SHIFT;
1182}
1183
1184/*
1185 * This should work even if CONFIG_PROC_FS isn't set, as proc_dointvec_minmax
1186 * will return an error.
1187 */
1188int pipe_proc_fn(struct ctl_table *table, int write, void __user *buf,
1189 size_t *lenp, loff_t *ppos)
1190{
1191 int ret;
1192
1193 ret = proc_dointvec_minmax(table, write, buf, lenp, ppos);
1194 if (ret < 0 || !write)
1195 return ret;
1196
1197 pipe_max_size = round_pipe_size(pipe_max_size);
1198 return ret;
1199}
1200
1201/*
1202 * After the inode slimming patch, i_pipe/i_bdev/i_cdev share the same
1203 * location, so checking ->i_pipe is not enough to verify that this is a
1204 * pipe.
1205 */
1206struct pipe_inode_info *get_pipe_info(struct file *file)
1207{
1208 struct inode *i = file->f_path.dentry->d_inode;
1209
1210 return S_ISFIFO(i->i_mode) ? i->i_pipe : NULL;
1211}
1212
1213long pipe_fcntl(struct file *file, unsigned int cmd, unsigned long arg)
1214{
1215 struct pipe_inode_info *pipe;
1216 long ret;
1217
1218 pipe = get_pipe_info(file);
1219 if (!pipe)
1220 return -EBADF;
1221
1222 mutex_lock(&pipe->inode->i_mutex);
1223
1224 switch (cmd) {
1225 case F_SETPIPE_SZ: {
1226 unsigned int size, nr_pages;
1227
1228 size = round_pipe_size(arg);
1229 nr_pages = size >> PAGE_SHIFT;
1230
1231 ret = -EINVAL;
1232 if (!nr_pages)
1233 goto out;
1234
1235 if (!capable(CAP_SYS_RESOURCE) && size > pipe_max_size) {
1236 ret = -EPERM;
1237 goto out;
1238 }
1239 ret = pipe_set_size(pipe, nr_pages);
1240 break;
1241 }
1242 case F_GETPIPE_SZ:
1243 ret = pipe->buffers * PAGE_SIZE;
1244 break;
1245 default:
1246 ret = -EINVAL;
1247 break;
1248 }
1249
1250out:
1251 mutex_unlock(&pipe->inode->i_mutex);
1252 return ret;
1253}
1254
1255static const struct super_operations pipefs_ops = {
1256 .destroy_inode = free_inode_nonrcu,
1257};
1258
1259/*
1260 * pipefs should _never_ be mounted by userland - too much of security hassle,
1261 * no real gain from having the whole whorehouse mounted. So we don't need
1262 * any operations on the root directory. However, we need a non-trivial
1263 * d_name - pipe: will go nicely and kill the special-casing in procfs.
1264 */
1265static struct dentry *pipefs_mount(struct file_system_type *fs_type,
1266 int flags, const char *dev_name, void *data)
1267{
1268 return mount_pseudo(fs_type, "pipe:", &pipefs_ops,
1269 &pipefs_dentry_operations, PIPEFS_MAGIC);
1270}
1271
1272static struct file_system_type pipe_fs_type = {
1273 .name = "pipefs",
1274 .mount = pipefs_mount,
1275 .kill_sb = kill_anon_super,
1276};
1277
1278static int __init init_pipe_fs(void)
1279{
1280 int err = register_filesystem(&pipe_fs_type);
1281
1282 if (!err) {
1283 pipe_mnt = kern_mount(&pipe_fs_type);
1284 if (IS_ERR(pipe_mnt)) {
1285 err = PTR_ERR(pipe_mnt);
1286 unregister_filesystem(&pipe_fs_type);
1287 }
1288 }
1289 return err;
1290}
1291
1292static void __exit exit_pipe_fs(void)
1293{
1294 kern_unmount(pipe_mnt);
1295 unregister_filesystem(&pipe_fs_type);
1296}
1297
1298fs_initcall(init_pipe_fs);
1299module_exit(exit_pipe_fs);
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);