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