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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/*
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);