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CommitLineData
1da177e4
LT
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>
35f3d14d 14#include <linux/log2.h>
1da177e4 15#include <linux/mount.h>
b502bd11 16#include <linux/magic.h>
1da177e4
LT
17#include <linux/pipe_fs_i.h>
18#include <linux/uio.h>
19#include <linux/highmem.h>
5274f052 20#include <linux/pagemap.h>
db349509 21#include <linux/audit.h>
ba719bae 22#include <linux/syscalls.h>
b492e95b 23#include <linux/fcntl.h>
d86133bd 24#include <linux/memcontrol.h>
1da177e4 25
7c0f6ba6 26#include <linux/uaccess.h>
1da177e4
LT
27#include <asm/ioctls.h>
28
599a0ac1
AV
29#include "internal.h"
30
b492e95b
JA
31/*
32 * The max size that a non-root user is allowed to grow the pipe. Can
ff9da691 33 * be set by root in /proc/sys/fs/pipe-max-size
b492e95b 34 */
ff9da691
JA
35unsigned int pipe_max_size = 1048576;
36
37/*
38 * Minimum pipe size, as required by POSIX
39 */
40unsigned int pipe_min_size = PAGE_SIZE;
b492e95b 41
759c0114
WT
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
1da177e4
LT
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
61e0d47c
MS
63static void pipe_lock_nested(struct pipe_inode_info *pipe, int subclass)
64{
6447a3cf 65 if (pipe->files)
72b0d9aa 66 mutex_lock_nested(&pipe->mutex, subclass);
61e0d47c
MS
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{
6447a3cf 80 if (pipe->files)
72b0d9aa 81 mutex_unlock(&pipe->mutex);
61e0d47c
MS
82}
83EXPORT_SYMBOL(pipe_unlock);
84
ebec73f4
AV
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
61e0d47c
MS
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 {
023d43c7
PZ
104 pipe_lock_nested(pipe2, I_MUTEX_PARENT);
105 pipe_lock_nested(pipe1, I_MUTEX_CHILD);
61e0d47c
MS
106 }
107}
108
1da177e4 109/* Drop the inode semaphore and wait for a pipe event, atomically */
3a326a2c 110void pipe_wait(struct pipe_inode_info *pipe)
1da177e4
LT
111{
112 DEFINE_WAIT(wait);
113
d79fc0fc
IM
114 /*
115 * Pipes are system-local resources, so sleeping on them
116 * is considered a noninteractive wait:
117 */
af927232 118 prepare_to_wait(&pipe->wait, &wait, TASK_INTERRUPTIBLE);
61e0d47c 119 pipe_unlock(pipe);
1da177e4 120 schedule();
3a326a2c 121 finish_wait(&pipe->wait, &wait);
61e0d47c 122 pipe_lock(pipe);
1da177e4
LT
123}
124
341b446b
IM
125static void anon_pipe_buf_release(struct pipe_inode_info *pipe,
126 struct pipe_buffer *buf)
1da177e4
LT
127{
128 struct page *page = buf->page;
129
5274f052
JA
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
341b446b 133 * allocation cache. (Otherwise just release our reference to it)
5274f052 134 */
341b446b 135 if (page_count(page) == 1 && !pipe->tmp_page)
923f4f23 136 pipe->tmp_page = page;
341b446b 137 else
09cbfeaf 138 put_page(page);
1da177e4
LT
139}
140
d86133bd
VD
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) {
c4159a75 147 if (memcg_kmem_enabled())
d86133bd 148 memcg_kmem_uncharge(page, 0);
d86133bd
VD
149 __SetPageLocked(page);
150 return 0;
151 }
152 return 1;
153}
154
0845718d 155/**
b51d63c6 156 * generic_pipe_buf_steal - attempt to take ownership of a &pipe_buffer
0845718d
JA
157 * @pipe: the pipe that the buffer belongs to
158 * @buf: the buffer to attempt to steal
159 *
160 * Description:
b51d63c6 161 * This function attempts to steal the &struct page attached to
0845718d
JA
162 * @buf. If successful, this function returns 0 and returns with
163 * the page locked. The caller may then reuse the page for whatever
b51d63c6 164 * he wishes; the typical use is insertion into a different file
0845718d
JA
165 * page cache.
166 */
330ab716
JA
167int generic_pipe_buf_steal(struct pipe_inode_info *pipe,
168 struct pipe_buffer *buf)
5abc97aa 169{
46e678c9
JA
170 struct page *page = buf->page;
171
0845718d
JA
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 */
46e678c9 177 if (page_count(page) == 1) {
46e678c9
JA
178 lock_page(page);
179 return 0;
180 }
181
182 return 1;
5abc97aa 183}
51921cb7 184EXPORT_SYMBOL(generic_pipe_buf_steal);
5abc97aa 185
0845718d 186/**
b51d63c6 187 * generic_pipe_buf_get - get a reference to a &struct pipe_buffer
0845718d
JA
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)
70524490 197{
09cbfeaf 198 get_page(buf->page);
70524490 199}
51921cb7 200EXPORT_SYMBOL(generic_pipe_buf_get);
70524490 201
0845718d
JA
202/**
203 * generic_pipe_buf_confirm - verify contents of the pipe buffer
79685b8d 204 * @info: the pipe that the buffer belongs to
0845718d
JA
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 */
cac36bb0
JA
211int generic_pipe_buf_confirm(struct pipe_inode_info *info,
212 struct pipe_buffer *buf)
f84d7519
JA
213{
214 return 0;
215}
51921cb7 216EXPORT_SYMBOL(generic_pipe_buf_confirm);
f84d7519 217
6818173b
MS
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{
09cbfeaf 229 put_page(buf->page);
6818173b 230}
51921cb7 231EXPORT_SYMBOL(generic_pipe_buf_release);
6818173b 232
d4c3cca9 233static const struct pipe_buf_operations anon_pipe_buf_ops = {
1da177e4 234 .can_merge = 1,
cac36bb0 235 .confirm = generic_pipe_buf_confirm,
1da177e4 236 .release = anon_pipe_buf_release,
d86133bd 237 .steal = anon_pipe_buf_steal,
f84d7519 238 .get = generic_pipe_buf_get,
1da177e4
LT
239};
240
9883035a
LT
241static const struct pipe_buf_operations packet_pipe_buf_ops = {
242 .can_merge = 0,
9883035a
LT
243 .confirm = generic_pipe_buf_confirm,
244 .release = anon_pipe_buf_release,
d86133bd 245 .steal = anon_pipe_buf_steal,
9883035a
LT
246 .get = generic_pipe_buf_get,
247};
248
1da177e4 249static ssize_t
fb9096a3 250pipe_read(struct kiocb *iocb, struct iov_iter *to)
1da177e4 251{
fb9096a3 252 size_t total_len = iov_iter_count(to);
ee0b3e67 253 struct file *filp = iocb->ki_filp;
de32ec4c 254 struct pipe_inode_info *pipe = filp->private_data;
1da177e4
LT
255 int do_wakeup;
256 ssize_t ret;
1da177e4 257
1da177e4
LT
258 /* Null read succeeds. */
259 if (unlikely(total_len == 0))
260 return 0;
261
262 do_wakeup = 0;
263 ret = 0;
ebec73f4 264 __pipe_lock(pipe);
1da177e4 265 for (;;) {
923f4f23 266 int bufs = pipe->nrbufs;
1da177e4 267 if (bufs) {
923f4f23
IM
268 int curbuf = pipe->curbuf;
269 struct pipe_buffer *buf = pipe->bufs + curbuf;
1da177e4 270 size_t chars = buf->len;
637b58c2
AV
271 size_t written;
272 int error;
1da177e4
LT
273
274 if (chars > total_len)
275 chars = total_len;
276
fba597db 277 error = pipe_buf_confirm(pipe, buf);
f84d7519 278 if (error) {
5274f052 279 if (!ret)
e5953cbd 280 ret = error;
5274f052
JA
281 break;
282 }
f84d7519 283
fb9096a3 284 written = copy_page_to_iter(buf->page, buf->offset, chars, to);
637b58c2 285 if (unlikely(written < chars)) {
341b446b 286 if (!ret)
637b58c2 287 ret = -EFAULT;
1da177e4
LT
288 break;
289 }
290 ret += chars;
291 buf->offset += chars;
292 buf->len -= chars;
9883035a
LT
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
1da177e4 300 if (!buf->len) {
a779638c 301 pipe_buf_release(pipe, buf);
35f3d14d 302 curbuf = (curbuf + 1) & (pipe->buffers - 1);
923f4f23
IM
303 pipe->curbuf = curbuf;
304 pipe->nrbufs = --bufs;
1da177e4
LT
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;
923f4f23 313 if (!pipe->writers)
1da177e4 314 break;
923f4f23 315 if (!pipe->waiting_writers) {
1da177e4
LT
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)) {
341b446b
IM
329 if (!ret)
330 ret = -ERESTARTSYS;
1da177e4
LT
331 break;
332 }
333 if (do_wakeup) {
28e58ee8 334 wake_up_interruptible_sync_poll(&pipe->wait, POLLOUT | POLLWRNORM);
923f4f23 335 kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT);
1da177e4 336 }
923f4f23 337 pipe_wait(pipe);
1da177e4 338 }
ebec73f4 339 __pipe_unlock(pipe);
341b446b
IM
340
341 /* Signal writers asynchronously that there is more room. */
1da177e4 342 if (do_wakeup) {
28e58ee8 343 wake_up_interruptible_sync_poll(&pipe->wait, POLLOUT | POLLWRNORM);
923f4f23 344 kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT);
1da177e4
LT
345 }
346 if (ret > 0)
347 file_accessed(filp);
348 return ret;
349}
350
9883035a
LT
351static inline int is_packetized(struct file *file)
352{
353 return (file->f_flags & O_DIRECT) != 0;
354}
355
1da177e4 356static ssize_t
f0d1bec9 357pipe_write(struct kiocb *iocb, struct iov_iter *from)
1da177e4 358{
ee0b3e67 359 struct file *filp = iocb->ki_filp;
de32ec4c 360 struct pipe_inode_info *pipe = filp->private_data;
f0d1bec9
AV
361 ssize_t ret = 0;
362 int do_wakeup = 0;
363 size_t total_len = iov_iter_count(from);
1da177e4
LT
364 ssize_t chars;
365
1da177e4
LT
366 /* Null write succeeds. */
367 if (unlikely(total_len == 0))
368 return 0;
369
ebec73f4 370 __pipe_lock(pipe);
1da177e4 371
923f4f23 372 if (!pipe->readers) {
1da177e4
LT
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 */
923f4f23 380 if (pipe->nrbufs && chars != 0) {
341b446b 381 int lastbuf = (pipe->curbuf + pipe->nrbufs - 1) &
35f3d14d 382 (pipe->buffers - 1);
923f4f23 383 struct pipe_buffer *buf = pipe->bufs + lastbuf;
1da177e4 384 int offset = buf->offset + buf->len;
341b446b 385
fba597db
MS
386 if (buf->ops->can_merge && offset + chars <= PAGE_SIZE) {
387 ret = pipe_buf_confirm(pipe, buf);
6ae08069 388 if (ret)
5274f052 389 goto out;
f84d7519 390
f0d1bec9
AV
391 ret = copy_page_from_iter(buf->page, offset, chars, from);
392 if (unlikely(ret < chars)) {
6ae08069 393 ret = -EFAULT;
1da177e4 394 goto out;
f6762b7a 395 }
f0d1bec9 396 do_wakeup = 1;
6ae08069 397 buf->len += ret;
f0d1bec9 398 if (!iov_iter_count(from))
1da177e4
LT
399 goto out;
400 }
401 }
402
403 for (;;) {
404 int bufs;
341b446b 405
923f4f23 406 if (!pipe->readers) {
1da177e4 407 send_sig(SIGPIPE, current, 0);
341b446b
IM
408 if (!ret)
409 ret = -EPIPE;
1da177e4
LT
410 break;
411 }
923f4f23 412 bufs = pipe->nrbufs;
35f3d14d
JA
413 if (bufs < pipe->buffers) {
414 int newbuf = (pipe->curbuf + bufs) & (pipe->buffers-1);
923f4f23
IM
415 struct pipe_buffer *buf = pipe->bufs + newbuf;
416 struct page *page = pipe->tmp_page;
f0d1bec9 417 int copied;
1da177e4
LT
418
419 if (!page) {
d86133bd 420 page = alloc_page(GFP_HIGHUSER | __GFP_ACCOUNT);
1da177e4
LT
421 if (unlikely(!page)) {
422 ret = ret ? : -ENOMEM;
423 break;
424 }
923f4f23 425 pipe->tmp_page = page;
1da177e4 426 }
341b446b 427 /* Always wake up, even if the copy fails. Otherwise
1da177e4
LT
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;
f0d1bec9
AV
433 copied = copy_page_from_iter(page, 0, PAGE_SIZE, from);
434 if (unlikely(copied < PAGE_SIZE && iov_iter_count(from))) {
341b446b 435 if (!ret)
f0d1bec9 436 ret = -EFAULT;
1da177e4
LT
437 break;
438 }
f0d1bec9 439 ret += copied;
1da177e4
LT
440
441 /* Insert it into the buffer array */
442 buf->page = page;
443 buf->ops = &anon_pipe_buf_ops;
444 buf->offset = 0;
f0d1bec9 445 buf->len = copied;
9883035a
LT
446 buf->flags = 0;
447 if (is_packetized(filp)) {
448 buf->ops = &packet_pipe_buf_ops;
449 buf->flags = PIPE_BUF_FLAG_PACKET;
450 }
923f4f23
IM
451 pipe->nrbufs = ++bufs;
452 pipe->tmp_page = NULL;
1da177e4 453
f0d1bec9 454 if (!iov_iter_count(from))
1da177e4
LT
455 break;
456 }
35f3d14d 457 if (bufs < pipe->buffers)
1da177e4
LT
458 continue;
459 if (filp->f_flags & O_NONBLOCK) {
341b446b
IM
460 if (!ret)
461 ret = -EAGAIN;
1da177e4
LT
462 break;
463 }
464 if (signal_pending(current)) {
341b446b
IM
465 if (!ret)
466 ret = -ERESTARTSYS;
1da177e4
LT
467 break;
468 }
469 if (do_wakeup) {
28e58ee8 470 wake_up_interruptible_sync_poll(&pipe->wait, POLLIN | POLLRDNORM);
923f4f23 471 kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
1da177e4
LT
472 do_wakeup = 0;
473 }
923f4f23
IM
474 pipe->waiting_writers++;
475 pipe_wait(pipe);
476 pipe->waiting_writers--;
1da177e4
LT
477 }
478out:
ebec73f4 479 __pipe_unlock(pipe);
1da177e4 480 if (do_wakeup) {
28e58ee8 481 wake_up_interruptible_sync_poll(&pipe->wait, POLLIN | POLLRDNORM);
923f4f23 482 kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
1da177e4 483 }
7e775f46 484 if (ret > 0 && sb_start_write_trylock(file_inode(filp)->i_sb)) {
c3b2da31
JB
485 int err = file_update_time(filp);
486 if (err)
487 ret = err;
7e775f46 488 sb_end_write(file_inode(filp)->i_sb);
c3b2da31 489 }
1da177e4
LT
490 return ret;
491}
492
d59d0b1b 493static long pipe_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
1da177e4 494{
de32ec4c 495 struct pipe_inode_info *pipe = filp->private_data;
1da177e4
LT
496 int count, buf, nrbufs;
497
498 switch (cmd) {
499 case FIONREAD:
ebec73f4 500 __pipe_lock(pipe);
1da177e4 501 count = 0;
923f4f23
IM
502 buf = pipe->curbuf;
503 nrbufs = pipe->nrbufs;
1da177e4 504 while (--nrbufs >= 0) {
923f4f23 505 count += pipe->bufs[buf].len;
35f3d14d 506 buf = (buf+1) & (pipe->buffers - 1);
1da177e4 507 }
ebec73f4 508 __pipe_unlock(pipe);
923f4f23 509
1da177e4
LT
510 return put_user(count, (int __user *)arg);
511 default:
46ce341b 512 return -ENOIOCTLCMD;
1da177e4
LT
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;
de32ec4c 521 struct pipe_inode_info *pipe = filp->private_data;
1da177e4
LT
522 int nrbufs;
523
923f4f23 524 poll_wait(filp, &pipe->wait, wait);
1da177e4
LT
525
526 /* Reading only -- no need for acquiring the semaphore. */
923f4f23 527 nrbufs = pipe->nrbufs;
1da177e4
LT
528 mask = 0;
529 if (filp->f_mode & FMODE_READ) {
530 mask = (nrbufs > 0) ? POLLIN | POLLRDNORM : 0;
923f4f23 531 if (!pipe->writers && filp->f_version != pipe->w_counter)
1da177e4
LT
532 mask |= POLLHUP;
533 }
534
535 if (filp->f_mode & FMODE_WRITE) {
35f3d14d 536 mask |= (nrbufs < pipe->buffers) ? POLLOUT | POLLWRNORM : 0;
5e5d7a22
PE
537 /*
538 * Most Unices do not set POLLERR for FIFOs but on Linux they
539 * behave exactly like pipes for poll().
540 */
923f4f23 541 if (!pipe->readers)
1da177e4
LT
542 mask |= POLLERR;
543 }
544
545 return mask;
546}
547
b0d8d229
LT
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
1da177e4 563static int
599a0ac1 564pipe_release(struct inode *inode, struct file *file)
1da177e4 565{
b0d8d229 566 struct pipe_inode_info *pipe = file->private_data;
923f4f23 567
ebec73f4 568 __pipe_lock(pipe);
599a0ac1
AV
569 if (file->f_mode & FMODE_READ)
570 pipe->readers--;
571 if (file->f_mode & FMODE_WRITE)
572 pipe->writers--;
341b446b 573
ba5bb147 574 if (pipe->readers || pipe->writers) {
28e58ee8 575 wake_up_interruptible_sync_poll(&pipe->wait, POLLIN | POLLOUT | POLLRDNORM | POLLWRNORM | POLLERR | POLLHUP);
923f4f23
IM
576 kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
577 kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT);
1da177e4 578 }
ebec73f4 579 __pipe_unlock(pipe);
ba5bb147 580
b0d8d229 581 put_pipe_info(inode, pipe);
1da177e4
LT
582 return 0;
583}
584
585static int
599a0ac1 586pipe_fasync(int fd, struct file *filp, int on)
1da177e4 587{
de32ec4c 588 struct pipe_inode_info *pipe = filp->private_data;
599a0ac1 589 int retval = 0;
1da177e4 590
ebec73f4 591 __pipe_lock(pipe);
599a0ac1
AV
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) {
341b446b 595 retval = fasync_helper(fd, filp, on, &pipe->fasync_writers);
599a0ac1
AV
596 if (retval < 0 && (filp->f_mode & FMODE_READ))
597 /* this can happen only if on == T */
e5bc49ba
ON
598 fasync_helper(-1, filp, 0, &pipe->fasync_readers);
599 }
ebec73f4 600 __pipe_unlock(pipe);
60aa4924 601 return retval;
1da177e4
LT
602}
603
9c87bcf0 604static unsigned long account_pipe_buffers(struct user_struct *user,
759c0114
WT
605 unsigned long old, unsigned long new)
606{
9c87bcf0 607 return atomic_long_add_return(new - old, &user->pipe_bufs);
759c0114
WT
608}
609
9c87bcf0 610static bool too_many_pipe_buffers_soft(unsigned long user_bufs)
759c0114 611{
9c87bcf0 612 return pipe_user_pages_soft && user_bufs >= pipe_user_pages_soft;
759c0114
WT
613}
614
9c87bcf0 615static bool too_many_pipe_buffers_hard(unsigned long user_bufs)
759c0114 616{
9c87bcf0 617 return pipe_user_pages_hard && user_bufs >= pipe_user_pages_hard;
759c0114
WT
618}
619
7bee130e 620struct pipe_inode_info *alloc_pipe_info(void)
3a326a2c 621{
923f4f23 622 struct pipe_inode_info *pipe;
09b4d199
MK
623 unsigned long pipe_bufs = PIPE_DEF_BUFFERS;
624 struct user_struct *user = get_current_user();
9c87bcf0 625 unsigned long user_bufs;
3a326a2c 626
d86133bd 627 pipe = kzalloc(sizeof(struct pipe_inode_info), GFP_KERNEL_ACCOUNT);
09b4d199
MK
628 if (pipe == NULL)
629 goto out_free_uid;
630
086e774a
MK
631 if (pipe_bufs * PAGE_SIZE > pipe_max_size && !capable(CAP_SYS_RESOURCE))
632 pipe_bufs = pipe_max_size >> PAGE_SHIFT;
633
9c87bcf0 634 user_bufs = account_pipe_buffers(user, 0, pipe_bufs);
a005ca0e 635
9c87bcf0
MK
636 if (too_many_pipe_buffers_soft(user_bufs)) {
637 user_bufs = account_pipe_buffers(user, pipe_bufs, 1);
a005ca0e 638 pipe_bufs = 1;
09b4d199 639 }
759c0114 640
9c87bcf0 641 if (too_many_pipe_buffers_hard(user_bufs))
a005ca0e
MK
642 goto out_revert_acct;
643
644 pipe->bufs = kcalloc(pipe_bufs, sizeof(struct pipe_buffer),
645 GFP_KERNEL_ACCOUNT);
646
09b4d199
MK
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;
09b4d199
MK
652 mutex_init(&pipe->mutex);
653 return pipe;
3a326a2c
IM
654 }
655
a005ca0e 656out_revert_acct:
9c87bcf0 657 (void) account_pipe_buffers(user, pipe_bufs, 0);
09b4d199
MK
658 kfree(pipe);
659out_free_uid:
660 free_uid(user);
35f3d14d 661 return NULL;
3a326a2c
IM
662}
663
4b8a8f1e 664void free_pipe_info(struct pipe_inode_info *pipe)
1da177e4
LT
665{
666 int i;
1da177e4 667
9c87bcf0 668 (void) account_pipe_buffers(pipe->user, pipe->buffers, 0);
759c0114 669 free_uid(pipe->user);
35f3d14d 670 for (i = 0; i < pipe->buffers; i++) {
923f4f23 671 struct pipe_buffer *buf = pipe->bufs + i;
1da177e4 672 if (buf->ops)
a779638c 673 pipe_buf_release(pipe, buf);
1da177e4 674 }
923f4f23
IM
675 if (pipe->tmp_page)
676 __free_page(pipe->tmp_page);
35f3d14d 677 kfree(pipe->bufs);
923f4f23 678 kfree(pipe);
1da177e4
LT
679}
680
fa3536cc 681static struct vfsmount *pipe_mnt __read_mostly;
341b446b 682
c23fbb6b
ED
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]",
75c3cfa8 689 d_inode(dentry)->i_ino);
c23fbb6b
ED
690}
691
3ba13d17 692static const struct dentry_operations pipefs_dentry_operations = {
c23fbb6b 693 .d_dname = pipefs_dname,
1da177e4
LT
694};
695
696static struct inode * get_pipe_inode(void)
697{
a209dfc7 698 struct inode *inode = new_inode_pseudo(pipe_mnt->mnt_sb);
923f4f23 699 struct pipe_inode_info *pipe;
1da177e4
LT
700
701 if (!inode)
702 goto fail_inode;
703
85fe4025
CH
704 inode->i_ino = get_next_ino();
705
7bee130e 706 pipe = alloc_pipe_info();
923f4f23 707 if (!pipe)
1da177e4 708 goto fail_iput;
3a326a2c 709
ba5bb147
AV
710 inode->i_pipe = pipe;
711 pipe->files = 2;
923f4f23 712 pipe->readers = pipe->writers = 1;
599a0ac1 713 inode->i_fop = &pipefifo_fops;
1da177e4
LT
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;
da9592ed
DH
723 inode->i_uid = current_fsuid();
724 inode->i_gid = current_fsgid();
078cd827 725 inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode);
923f4f23 726
1da177e4
LT
727 return inode;
728
729fail_iput:
730 iput(inode);
341b446b 731
1da177e4
LT
732fail_inode:
733 return NULL;
734}
735
e4fad8e5 736int create_pipe_files(struct file **res, int flags)
1da177e4 737{
d6cbd281 738 int err;
e4fad8e5 739 struct inode *inode = get_pipe_inode();
d6cbd281 740 struct file *f;
2c48b9c4 741 struct path path;
e4fad8e5 742 static struct qstr name = { .name = "" };
1da177e4 743
1da177e4 744 if (!inode)
e4fad8e5 745 return -ENFILE;
1da177e4 746
d6cbd281 747 err = -ENOMEM;
4b936885 748 path.dentry = d_alloc_pseudo(pipe_mnt->mnt_sb, &name);
2c48b9c4 749 if (!path.dentry)
d6cbd281 750 goto err_inode;
2c48b9c4 751 path.mnt = mntget(pipe_mnt);
341b446b 752
2c48b9c4 753 d_instantiate(path.dentry, inode);
430e285e 754
599a0ac1 755 f = alloc_file(&path, FMODE_WRITE, &pipefifo_fops);
e9bb1f9b
EB
756 if (IS_ERR(f)) {
757 err = PTR_ERR(f);
430e285e 758 goto err_dentry;
e9bb1f9b 759 }
341b446b 760
9883035a 761 f->f_flags = O_WRONLY | (flags & (O_NONBLOCK | O_DIRECT));
de32ec4c 762 f->private_data = inode->i_pipe;
d6cbd281 763
599a0ac1 764 res[0] = alloc_file(&path, FMODE_READ, &pipefifo_fops);
e9bb1f9b
EB
765 if (IS_ERR(res[0])) {
766 err = PTR_ERR(res[0]);
e4fad8e5 767 goto err_file;
e9bb1f9b 768 }
e4fad8e5
AV
769
770 path_get(&path);
de32ec4c 771 res[0]->private_data = inode->i_pipe;
e4fad8e5
AV
772 res[0]->f_flags = O_RDONLY | (flags & O_NONBLOCK);
773 res[1] = f;
774 return 0;
1da177e4 775
e4fad8e5
AV
776err_file:
777 put_filp(f);
778err_dentry:
4b8a8f1e 779 free_pipe_info(inode->i_pipe);
2c48b9c4 780 path_put(&path);
e4fad8e5 781 return err;
ed152437 782
e4fad8e5 783err_inode:
4b8a8f1e 784 free_pipe_info(inode->i_pipe);
1da177e4 785 iput(inode);
e4fad8e5 786 return err;
d6cbd281
AK
787}
788
5b249b1b 789static int __do_pipe_flags(int *fd, struct file **files, int flags)
d6cbd281 790{
d6cbd281
AK
791 int error;
792 int fdw, fdr;
793
9883035a 794 if (flags & ~(O_CLOEXEC | O_NONBLOCK | O_DIRECT))
ed8cae8b
UD
795 return -EINVAL;
796
e4fad8e5
AV
797 error = create_pipe_files(files, flags);
798 if (error)
799 return error;
d6cbd281 800
ed8cae8b 801 error = get_unused_fd_flags(flags);
d6cbd281
AK
802 if (error < 0)
803 goto err_read_pipe;
804 fdr = error;
805
ed8cae8b 806 error = get_unused_fd_flags(flags);
d6cbd281
AK
807 if (error < 0)
808 goto err_fdr;
809 fdw = error;
810
157cf649 811 audit_fd_pair(fdr, fdw);
d6cbd281
AK
812 fd[0] = fdr;
813 fd[1] = fdw;
d6cbd281
AK
814 return 0;
815
816 err_fdr:
817 put_unused_fd(fdr);
818 err_read_pipe:
e4fad8e5
AV
819 fput(files[0]);
820 fput(files[1]);
d6cbd281 821 return error;
1da177e4
LT
822}
823
5b249b1b
AV
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
d35c7b0e
UD
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 */
d4e82042 839SYSCALL_DEFINE2(pipe2, int __user *, fildes, int, flags)
d35c7b0e 840{
5b249b1b 841 struct file *files[2];
d35c7b0e
UD
842 int fd[2];
843 int error;
844
5b249b1b 845 error = __do_pipe_flags(fd, files, flags);
d35c7b0e 846 if (!error) {
5b249b1b
AV
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]);
d35c7b0e 852 error = -EFAULT;
5b249b1b
AV
853 } else {
854 fd_install(fd[0], files[0]);
855 fd_install(fd[1], files[1]);
ba719bae 856 }
d35c7b0e
UD
857 }
858 return error;
859}
860
2b664219 861SYSCALL_DEFINE1(pipe, int __user *, fildes)
ed8cae8b
UD
862{
863 return sys_pipe2(fildes, 0);
864}
865
fc7478a2 866static int wait_for_partner(struct pipe_inode_info *pipe, unsigned int *cnt)
f776c738
AV
867{
868 int cur = *cnt;
869
870 while (cur == *cnt) {
fc7478a2 871 pipe_wait(pipe);
f776c738
AV
872 if (signal_pending(current))
873 break;
874 }
875 return cur == *cnt ? -ERESTARTSYS : 0;
876}
877
fc7478a2 878static void wake_up_partner(struct pipe_inode_info *pipe)
f776c738 879{
fc7478a2 880 wake_up_interruptible(&pipe->wait);
f776c738
AV
881}
882
883static int fifo_open(struct inode *inode, struct file *filp)
884{
885 struct pipe_inode_info *pipe;
599a0ac1 886 bool is_pipe = inode->i_sb->s_magic == PIPEFS_MAGIC;
f776c738
AV
887 int ret;
888
ba5bb147
AV
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);
7bee130e 898 pipe = alloc_pipe_info();
f776c738 899 if (!pipe)
ba5bb147
AV
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);
4b8a8f1e 906 free_pipe_info(pipe);
ba5bb147
AV
907 pipe = inode->i_pipe;
908 } else {
909 inode->i_pipe = pipe;
910 spin_unlock(&inode->i_lock);
911 }
f776c738 912 }
de32ec4c 913 filp->private_data = pipe;
ba5bb147
AV
914 /* OK, we have a pipe and it's pinned down */
915
ebec73f4 916 __pipe_lock(pipe);
f776c738
AV
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 */
f776c738
AV
928 pipe->r_counter++;
929 if (pipe->readers++ == 0)
fc7478a2 930 wake_up_partner(pipe);
f776c738 931
599a0ac1 932 if (!is_pipe && !pipe->writers) {
f776c738
AV
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 {
fc7478a2 938 if (wait_for_partner(pipe, &pipe->w_counter))
f776c738
AV
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;
599a0ac1 951 if (!is_pipe && (filp->f_flags & O_NONBLOCK) && !pipe->readers)
f776c738
AV
952 goto err;
953
f776c738
AV
954 pipe->w_counter++;
955 if (!pipe->writers++)
fc7478a2 956 wake_up_partner(pipe);
f776c738 957
599a0ac1 958 if (!is_pipe && !pipe->readers) {
fc7478a2 959 if (wait_for_partner(pipe, &pipe->r_counter))
f776c738
AV
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 */
f776c738
AV
971
972 pipe->readers++;
973 pipe->writers++;
974 pipe->r_counter++;
975 pipe->w_counter++;
976 if (pipe->readers == 1 || pipe->writers == 1)
fc7478a2 977 wake_up_partner(pipe);
f776c738
AV
978 break;
979
980 default:
981 ret = -EINVAL;
982 goto err;
983 }
984
985 /* Ok! */
ebec73f4 986 __pipe_unlock(pipe);
f776c738
AV
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:
ebec73f4 1002 __pipe_unlock(pipe);
b0d8d229
LT
1003
1004 put_pipe_info(inode, pipe);
f776c738
AV
1005 return ret;
1006}
1007
599a0ac1
AV
1008const struct file_operations pipefifo_fops = {
1009 .open = fifo_open,
1010 .llseek = no_llseek,
fb9096a3 1011 .read_iter = pipe_read,
f0d1bec9 1012 .write_iter = pipe_write,
599a0ac1
AV
1013 .poll = pipe_poll,
1014 .unlocked_ioctl = pipe_ioctl,
1015 .release = pipe_release,
1016 .fasync = pipe_fasync,
f776c738
AV
1017};
1018
f491bd71
MK
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
35f3d14d
JA
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 */
d37d4166 1035static long pipe_set_size(struct pipe_inode_info *pipe, unsigned long arg)
35f3d14d
JA
1036{
1037 struct pipe_buffer *bufs;
d37d4166 1038 unsigned int size, nr_pages;
9c87bcf0 1039 unsigned long user_bufs;
b0b91d18 1040 long ret = 0;
d37d4166
MK
1041
1042 size = round_pipe_size(arg);
1043 nr_pages = size >> PAGE_SHIFT;
1044
1045 if (!nr_pages)
1046 return -EINVAL;
1047
b0b91d18
MK
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))
d37d4166
MK
1057 return -EPERM;
1058
9c87bcf0 1059 user_bufs = account_pipe_buffers(pipe->user, pipe->buffers, nr_pages);
b0b91d18
MK
1060
1061 if (nr_pages > pipe->buffers &&
9c87bcf0
MK
1062 (too_many_pipe_buffers_hard(user_bufs) ||
1063 too_many_pipe_buffers_soft(user_bufs)) &&
b0b91d18
MK
1064 !capable(CAP_SYS_RESOURCE) && !capable(CAP_SYS_ADMIN)) {
1065 ret = -EPERM;
1066 goto out_revert_acct;
1067 }
35f3d14d 1068
35f3d14d
JA
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 */
b0b91d18
MK
1075 if (nr_pages < pipe->nrbufs) {
1076 ret = -EBUSY;
1077 goto out_revert_acct;
1078 }
35f3d14d 1079
d86133bd
VD
1080 bufs = kcalloc(nr_pages, sizeof(*bufs),
1081 GFP_KERNEL_ACCOUNT | __GFP_NOWARN);
b0b91d18
MK
1082 if (unlikely(!bufs)) {
1083 ret = -ENOMEM;
1084 goto out_revert_acct;
1085 }
35f3d14d
JA
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) {
1d862f41
MS
1092 unsigned int tail;
1093 unsigned int head;
35f3d14d 1094
1d862f41
MS
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;
35f3d14d
JA
1102 if (head)
1103 memcpy(bufs, pipe->bufs + pipe->curbuf, head * sizeof(struct pipe_buffer));
1104 if (tail)
1d862f41 1105 memcpy(bufs + head, pipe->bufs, tail * sizeof(struct pipe_buffer));
35f3d14d
JA
1106 }
1107
1108 pipe->curbuf = 0;
1109 kfree(pipe->bufs);
1110 pipe->bufs = bufs;
b9598db3
JA
1111 pipe->buffers = nr_pages;
1112 return nr_pages * PAGE_SIZE;
b0b91d18
MK
1113
1114out_revert_acct:
9c87bcf0 1115 (void) account_pipe_buffers(pipe->user, nr_pages, pipe->buffers);
b0b91d18 1116 return ret;
35f3d14d
JA
1117}
1118
ff9da691
JA
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
72083646
LT
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{
de32ec4c 1143 return file->f_op == &pipefifo_fops ? file->private_data : NULL;
72083646
LT
1144}
1145
35f3d14d
JA
1146long pipe_fcntl(struct file *file, unsigned int cmd, unsigned long arg)
1147{
1148 struct pipe_inode_info *pipe;
1149 long ret;
1150
c66fb347 1151 pipe = get_pipe_info(file);
35f3d14d
JA
1152 if (!pipe)
1153 return -EBADF;
1154
ebec73f4 1155 __pipe_lock(pipe);
35f3d14d
JA
1156
1157 switch (cmd) {
d37d4166
MK
1158 case F_SETPIPE_SZ:
1159 ret = pipe_set_size(pipe, arg);
35f3d14d
JA
1160 break;
1161 case F_GETPIPE_SZ:
b9598db3 1162 ret = pipe->buffers * PAGE_SIZE;
35f3d14d
JA
1163 break;
1164 default:
1165 ret = -EINVAL;
1166 break;
1167 }
1168
ebec73f4 1169 __pipe_unlock(pipe);
35f3d14d
JA
1170 return ret;
1171}
1172
ff0c7d15
NP
1173static const struct super_operations pipefs_ops = {
1174 .destroy_inode = free_inode_nonrcu,
d70ef97b 1175 .statfs = simple_statfs,
ff0c7d15
NP
1176};
1177
1da177e4
LT
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 */
51139ada
AV
1184static struct dentry *pipefs_mount(struct file_system_type *fs_type,
1185 int flags, const char *dev_name, void *data)
1da177e4 1186{
c74a1cbb
AV
1187 return mount_pseudo(fs_type, "pipe:", &pipefs_ops,
1188 &pipefs_dentry_operations, PIPEFS_MAGIC);
1da177e4
LT
1189}
1190
1191static struct file_system_type pipe_fs_type = {
1192 .name = "pipefs",
51139ada 1193 .mount = pipefs_mount,
1da177e4
LT
1194 .kill_sb = kill_anon_super,
1195};
1196
1197static int __init init_pipe_fs(void)
1198{
1199 int err = register_filesystem(&pipe_fs_type);
341b446b 1200
1da177e4
LT
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
1da177e4 1211fs_initcall(init_pipe_fs);