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