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[mirror_ubuntu-artful-kernel.git] / fs / pipe.c
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>
1da177e4
LT
24
25#include <asm/uaccess.h>
26#include <asm/ioctls.h>
27
599a0ac1
AV
28#include "internal.h"
29
b492e95b
JA
30/*
31 * The max size that a non-root user is allowed to grow the pipe. Can
ff9da691 32 * be set by root in /proc/sys/fs/pipe-max-size
b492e95b 33 */
ff9da691
JA
34unsigned int pipe_max_size = 1048576;
35
36/*
37 * Minimum pipe size, as required by POSIX
38 */
39unsigned int pipe_min_size = PAGE_SIZE;
b492e95b 40
759c0114
WT
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
1da177e4
LT
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
61e0d47c
MS
62static void pipe_lock_nested(struct pipe_inode_info *pipe, int subclass)
63{
6447a3cf 64 if (pipe->files)
72b0d9aa 65 mutex_lock_nested(&pipe->mutex, subclass);
61e0d47c
MS
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{
6447a3cf 79 if (pipe->files)
72b0d9aa 80 mutex_unlock(&pipe->mutex);
61e0d47c
MS
81}
82EXPORT_SYMBOL(pipe_unlock);
83
ebec73f4
AV
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
61e0d47c
MS
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 {
023d43c7
PZ
103 pipe_lock_nested(pipe2, I_MUTEX_PARENT);
104 pipe_lock_nested(pipe1, I_MUTEX_CHILD);
61e0d47c
MS
105 }
106}
107
1da177e4 108/* Drop the inode semaphore and wait for a pipe event, atomically */
3a326a2c 109void pipe_wait(struct pipe_inode_info *pipe)
1da177e4
LT
110{
111 DEFINE_WAIT(wait);
112
d79fc0fc
IM
113 /*
114 * Pipes are system-local resources, so sleeping on them
115 * is considered a noninteractive wait:
116 */
af927232 117 prepare_to_wait(&pipe->wait, &wait, TASK_INTERRUPTIBLE);
61e0d47c 118 pipe_unlock(pipe);
1da177e4 119 schedule();
3a326a2c 120 finish_wait(&pipe->wait, &wait);
61e0d47c 121 pipe_lock(pipe);
1da177e4
LT
122}
123
341b446b
IM
124static void anon_pipe_buf_release(struct pipe_inode_info *pipe,
125 struct pipe_buffer *buf)
1da177e4
LT
126{
127 struct page *page = buf->page;
128
5274f052
JA
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
341b446b 132 * allocation cache. (Otherwise just release our reference to it)
5274f052 133 */
341b446b 134 if (page_count(page) == 1 && !pipe->tmp_page)
923f4f23 135 pipe->tmp_page = page;
341b446b 136 else
09cbfeaf 137 put_page(page);
1da177e4
LT
138}
139
0845718d 140/**
b51d63c6 141 * generic_pipe_buf_steal - attempt to take ownership of a &pipe_buffer
0845718d
JA
142 * @pipe: the pipe that the buffer belongs to
143 * @buf: the buffer to attempt to steal
144 *
145 * Description:
b51d63c6 146 * This function attempts to steal the &struct page attached to
0845718d
JA
147 * @buf. If successful, this function returns 0 and returns with
148 * the page locked. The caller may then reuse the page for whatever
b51d63c6 149 * he wishes; the typical use is insertion into a different file
0845718d
JA
150 * page cache.
151 */
330ab716
JA
152int generic_pipe_buf_steal(struct pipe_inode_info *pipe,
153 struct pipe_buffer *buf)
5abc97aa 154{
46e678c9
JA
155 struct page *page = buf->page;
156
0845718d
JA
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 */
46e678c9 162 if (page_count(page) == 1) {
46e678c9
JA
163 lock_page(page);
164 return 0;
165 }
166
167 return 1;
5abc97aa 168}
51921cb7 169EXPORT_SYMBOL(generic_pipe_buf_steal);
5abc97aa 170
0845718d 171/**
b51d63c6 172 * generic_pipe_buf_get - get a reference to a &struct pipe_buffer
0845718d
JA
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)
70524490 182{
09cbfeaf 183 get_page(buf->page);
70524490 184}
51921cb7 185EXPORT_SYMBOL(generic_pipe_buf_get);
70524490 186
0845718d
JA
187/**
188 * generic_pipe_buf_confirm - verify contents of the pipe buffer
79685b8d 189 * @info: the pipe that the buffer belongs to
0845718d
JA
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 */
cac36bb0
JA
196int generic_pipe_buf_confirm(struct pipe_inode_info *info,
197 struct pipe_buffer *buf)
f84d7519
JA
198{
199 return 0;
200}
51921cb7 201EXPORT_SYMBOL(generic_pipe_buf_confirm);
f84d7519 202
6818173b
MS
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{
09cbfeaf 214 put_page(buf->page);
6818173b 215}
51921cb7 216EXPORT_SYMBOL(generic_pipe_buf_release);
6818173b 217
d4c3cca9 218static const struct pipe_buf_operations anon_pipe_buf_ops = {
1da177e4 219 .can_merge = 1,
cac36bb0 220 .confirm = generic_pipe_buf_confirm,
1da177e4 221 .release = anon_pipe_buf_release,
330ab716 222 .steal = generic_pipe_buf_steal,
f84d7519 223 .get = generic_pipe_buf_get,
1da177e4
LT
224};
225
9883035a
LT
226static const struct pipe_buf_operations packet_pipe_buf_ops = {
227 .can_merge = 0,
9883035a
LT
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
1da177e4 234static ssize_t
fb9096a3 235pipe_read(struct kiocb *iocb, struct iov_iter *to)
1da177e4 236{
fb9096a3 237 size_t total_len = iov_iter_count(to);
ee0b3e67 238 struct file *filp = iocb->ki_filp;
de32ec4c 239 struct pipe_inode_info *pipe = filp->private_data;
1da177e4
LT
240 int do_wakeup;
241 ssize_t ret;
1da177e4 242
1da177e4
LT
243 /* Null read succeeds. */
244 if (unlikely(total_len == 0))
245 return 0;
246
247 do_wakeup = 0;
248 ret = 0;
ebec73f4 249 __pipe_lock(pipe);
1da177e4 250 for (;;) {
923f4f23 251 int bufs = pipe->nrbufs;
1da177e4 252 if (bufs) {
923f4f23
IM
253 int curbuf = pipe->curbuf;
254 struct pipe_buffer *buf = pipe->bufs + curbuf;
d4c3cca9 255 const struct pipe_buf_operations *ops = buf->ops;
1da177e4 256 size_t chars = buf->len;
637b58c2
AV
257 size_t written;
258 int error;
1da177e4
LT
259
260 if (chars > total_len)
261 chars = total_len;
262
cac36bb0 263 error = ops->confirm(pipe, buf);
f84d7519 264 if (error) {
5274f052 265 if (!ret)
e5953cbd 266 ret = error;
5274f052
JA
267 break;
268 }
f84d7519 269
fb9096a3 270 written = copy_page_to_iter(buf->page, buf->offset, chars, to);
637b58c2 271 if (unlikely(written < chars)) {
341b446b 272 if (!ret)
637b58c2 273 ret = -EFAULT;
1da177e4
LT
274 break;
275 }
276 ret += chars;
277 buf->offset += chars;
278 buf->len -= chars;
9883035a
LT
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
1da177e4
LT
286 if (!buf->len) {
287 buf->ops = NULL;
923f4f23 288 ops->release(pipe, buf);
35f3d14d 289 curbuf = (curbuf + 1) & (pipe->buffers - 1);
923f4f23
IM
290 pipe->curbuf = curbuf;
291 pipe->nrbufs = --bufs;
1da177e4
LT
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;
923f4f23 300 if (!pipe->writers)
1da177e4 301 break;
923f4f23 302 if (!pipe->waiting_writers) {
1da177e4
LT
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)) {
341b446b
IM
316 if (!ret)
317 ret = -ERESTARTSYS;
1da177e4
LT
318 break;
319 }
320 if (do_wakeup) {
28e58ee8 321 wake_up_interruptible_sync_poll(&pipe->wait, POLLOUT | POLLWRNORM);
923f4f23 322 kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT);
1da177e4 323 }
923f4f23 324 pipe_wait(pipe);
1da177e4 325 }
ebec73f4 326 __pipe_unlock(pipe);
341b446b
IM
327
328 /* Signal writers asynchronously that there is more room. */
1da177e4 329 if (do_wakeup) {
28e58ee8 330 wake_up_interruptible_sync_poll(&pipe->wait, POLLOUT | POLLWRNORM);
923f4f23 331 kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT);
1da177e4
LT
332 }
333 if (ret > 0)
334 file_accessed(filp);
335 return ret;
336}
337
9883035a
LT
338static inline int is_packetized(struct file *file)
339{
340 return (file->f_flags & O_DIRECT) != 0;
341}
342
1da177e4 343static ssize_t
f0d1bec9 344pipe_write(struct kiocb *iocb, struct iov_iter *from)
1da177e4 345{
ee0b3e67 346 struct file *filp = iocb->ki_filp;
de32ec4c 347 struct pipe_inode_info *pipe = filp->private_data;
f0d1bec9
AV
348 ssize_t ret = 0;
349 int do_wakeup = 0;
350 size_t total_len = iov_iter_count(from);
1da177e4
LT
351 ssize_t chars;
352
1da177e4
LT
353 /* Null write succeeds. */
354 if (unlikely(total_len == 0))
355 return 0;
356
ebec73f4 357 __pipe_lock(pipe);
1da177e4 358
923f4f23 359 if (!pipe->readers) {
1da177e4
LT
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 */
923f4f23 367 if (pipe->nrbufs && chars != 0) {
341b446b 368 int lastbuf = (pipe->curbuf + pipe->nrbufs - 1) &
35f3d14d 369 (pipe->buffers - 1);
923f4f23 370 struct pipe_buffer *buf = pipe->bufs + lastbuf;
d4c3cca9 371 const struct pipe_buf_operations *ops = buf->ops;
1da177e4 372 int offset = buf->offset + buf->len;
341b446b 373
1da177e4 374 if (ops->can_merge && offset + chars <= PAGE_SIZE) {
6ae08069
EB
375 ret = ops->confirm(pipe, buf);
376 if (ret)
5274f052 377 goto out;
f84d7519 378
f0d1bec9
AV
379 ret = copy_page_from_iter(buf->page, offset, chars, from);
380 if (unlikely(ret < chars)) {
6ae08069 381 ret = -EFAULT;
1da177e4 382 goto out;
f6762b7a 383 }
f0d1bec9 384 do_wakeup = 1;
6ae08069 385 buf->len += ret;
f0d1bec9 386 if (!iov_iter_count(from))
1da177e4
LT
387 goto out;
388 }
389 }
390
391 for (;;) {
392 int bufs;
341b446b 393
923f4f23 394 if (!pipe->readers) {
1da177e4 395 send_sig(SIGPIPE, current, 0);
341b446b
IM
396 if (!ret)
397 ret = -EPIPE;
1da177e4
LT
398 break;
399 }
923f4f23 400 bufs = pipe->nrbufs;
35f3d14d
JA
401 if (bufs < pipe->buffers) {
402 int newbuf = (pipe->curbuf + bufs) & (pipe->buffers-1);
923f4f23
IM
403 struct pipe_buffer *buf = pipe->bufs + newbuf;
404 struct page *page = pipe->tmp_page;
f0d1bec9 405 int copied;
1da177e4
LT
406
407 if (!page) {
408 page = alloc_page(GFP_HIGHUSER);
409 if (unlikely(!page)) {
410 ret = ret ? : -ENOMEM;
411 break;
412 }
923f4f23 413 pipe->tmp_page = page;
1da177e4 414 }
341b446b 415 /* Always wake up, even if the copy fails. Otherwise
1da177e4
LT
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;
f0d1bec9
AV
421 copied = copy_page_from_iter(page, 0, PAGE_SIZE, from);
422 if (unlikely(copied < PAGE_SIZE && iov_iter_count(from))) {
341b446b 423 if (!ret)
f0d1bec9 424 ret = -EFAULT;
1da177e4
LT
425 break;
426 }
f0d1bec9 427 ret += copied;
1da177e4
LT
428
429 /* Insert it into the buffer array */
430 buf->page = page;
431 buf->ops = &anon_pipe_buf_ops;
432 buf->offset = 0;
f0d1bec9 433 buf->len = copied;
9883035a
LT
434 buf->flags = 0;
435 if (is_packetized(filp)) {
436 buf->ops = &packet_pipe_buf_ops;
437 buf->flags = PIPE_BUF_FLAG_PACKET;
438 }
923f4f23
IM
439 pipe->nrbufs = ++bufs;
440 pipe->tmp_page = NULL;
1da177e4 441
f0d1bec9 442 if (!iov_iter_count(from))
1da177e4
LT
443 break;
444 }
35f3d14d 445 if (bufs < pipe->buffers)
1da177e4
LT
446 continue;
447 if (filp->f_flags & O_NONBLOCK) {
341b446b
IM
448 if (!ret)
449 ret = -EAGAIN;
1da177e4
LT
450 break;
451 }
452 if (signal_pending(current)) {
341b446b
IM
453 if (!ret)
454 ret = -ERESTARTSYS;
1da177e4
LT
455 break;
456 }
457 if (do_wakeup) {
28e58ee8 458 wake_up_interruptible_sync_poll(&pipe->wait, POLLIN | POLLRDNORM);
923f4f23 459 kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
1da177e4
LT
460 do_wakeup = 0;
461 }
923f4f23
IM
462 pipe->waiting_writers++;
463 pipe_wait(pipe);
464 pipe->waiting_writers--;
1da177e4
LT
465 }
466out:
ebec73f4 467 __pipe_unlock(pipe);
1da177e4 468 if (do_wakeup) {
28e58ee8 469 wake_up_interruptible_sync_poll(&pipe->wait, POLLIN | POLLRDNORM);
923f4f23 470 kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
1da177e4 471 }
7e775f46 472 if (ret > 0 && sb_start_write_trylock(file_inode(filp)->i_sb)) {
c3b2da31
JB
473 int err = file_update_time(filp);
474 if (err)
475 ret = err;
7e775f46 476 sb_end_write(file_inode(filp)->i_sb);
c3b2da31 477 }
1da177e4
LT
478 return ret;
479}
480
d59d0b1b 481static long pipe_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
1da177e4 482{
de32ec4c 483 struct pipe_inode_info *pipe = filp->private_data;
1da177e4
LT
484 int count, buf, nrbufs;
485
486 switch (cmd) {
487 case FIONREAD:
ebec73f4 488 __pipe_lock(pipe);
1da177e4 489 count = 0;
923f4f23
IM
490 buf = pipe->curbuf;
491 nrbufs = pipe->nrbufs;
1da177e4 492 while (--nrbufs >= 0) {
923f4f23 493 count += pipe->bufs[buf].len;
35f3d14d 494 buf = (buf+1) & (pipe->buffers - 1);
1da177e4 495 }
ebec73f4 496 __pipe_unlock(pipe);
923f4f23 497
1da177e4
LT
498 return put_user(count, (int __user *)arg);
499 default:
46ce341b 500 return -ENOIOCTLCMD;
1da177e4
LT
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;
de32ec4c 509 struct pipe_inode_info *pipe = filp->private_data;
1da177e4
LT
510 int nrbufs;
511
923f4f23 512 poll_wait(filp, &pipe->wait, wait);
1da177e4
LT
513
514 /* Reading only -- no need for acquiring the semaphore. */
923f4f23 515 nrbufs = pipe->nrbufs;
1da177e4
LT
516 mask = 0;
517 if (filp->f_mode & FMODE_READ) {
518 mask = (nrbufs > 0) ? POLLIN | POLLRDNORM : 0;
923f4f23 519 if (!pipe->writers && filp->f_version != pipe->w_counter)
1da177e4
LT
520 mask |= POLLHUP;
521 }
522
523 if (filp->f_mode & FMODE_WRITE) {
35f3d14d 524 mask |= (nrbufs < pipe->buffers) ? POLLOUT | POLLWRNORM : 0;
5e5d7a22
PE
525 /*
526 * Most Unices do not set POLLERR for FIFOs but on Linux they
527 * behave exactly like pipes for poll().
528 */
923f4f23 529 if (!pipe->readers)
1da177e4
LT
530 mask |= POLLERR;
531 }
532
533 return mask;
534}
535
b0d8d229
LT
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
1da177e4 551static int
599a0ac1 552pipe_release(struct inode *inode, struct file *file)
1da177e4 553{
b0d8d229 554 struct pipe_inode_info *pipe = file->private_data;
923f4f23 555
ebec73f4 556 __pipe_lock(pipe);
599a0ac1
AV
557 if (file->f_mode & FMODE_READ)
558 pipe->readers--;
559 if (file->f_mode & FMODE_WRITE)
560 pipe->writers--;
341b446b 561
ba5bb147 562 if (pipe->readers || pipe->writers) {
28e58ee8 563 wake_up_interruptible_sync_poll(&pipe->wait, POLLIN | POLLOUT | POLLRDNORM | POLLWRNORM | POLLERR | POLLHUP);
923f4f23
IM
564 kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
565 kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT);
1da177e4 566 }
ebec73f4 567 __pipe_unlock(pipe);
ba5bb147 568
b0d8d229 569 put_pipe_info(inode, pipe);
1da177e4
LT
570 return 0;
571}
572
573static int
599a0ac1 574pipe_fasync(int fd, struct file *filp, int on)
1da177e4 575{
de32ec4c 576 struct pipe_inode_info *pipe = filp->private_data;
599a0ac1 577 int retval = 0;
1da177e4 578
ebec73f4 579 __pipe_lock(pipe);
599a0ac1
AV
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) {
341b446b 583 retval = fasync_helper(fd, filp, on, &pipe->fasync_writers);
599a0ac1
AV
584 if (retval < 0 && (filp->f_mode & FMODE_READ))
585 /* this can happen only if on == T */
e5bc49ba
ON
586 fasync_helper(-1, filp, 0, &pipe->fasync_readers);
587 }
ebec73f4 588 __pipe_unlock(pipe);
60aa4924 589 return retval;
1da177e4
LT
590}
591
759c0114
WT
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
7bee130e 610struct pipe_inode_info *alloc_pipe_info(void)
3a326a2c 611{
923f4f23 612 struct pipe_inode_info *pipe;
3a326a2c 613
923f4f23
IM
614 pipe = kzalloc(sizeof(struct pipe_inode_info), GFP_KERNEL);
615 if (pipe) {
759c0114
WT
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
35f3d14d
JA
625 if (pipe->bufs) {
626 init_waitqueue_head(&pipe->wait);
627 pipe->r_counter = pipe->w_counter = 1;
759c0114
WT
628 pipe->buffers = pipe_bufs;
629 pipe->user = user;
630 account_pipe_buffers(pipe, 0, pipe_bufs);
72b0d9aa 631 mutex_init(&pipe->mutex);
35f3d14d
JA
632 return pipe;
633 }
759c0114 634 free_uid(user);
35f3d14d 635 kfree(pipe);
3a326a2c
IM
636 }
637
35f3d14d 638 return NULL;
3a326a2c
IM
639}
640
4b8a8f1e 641void free_pipe_info(struct pipe_inode_info *pipe)
1da177e4
LT
642{
643 int i;
1da177e4 644
759c0114
WT
645 account_pipe_buffers(pipe, pipe->buffers, 0);
646 free_uid(pipe->user);
35f3d14d 647 for (i = 0; i < pipe->buffers; i++) {
923f4f23 648 struct pipe_buffer *buf = pipe->bufs + i;
1da177e4 649 if (buf->ops)
923f4f23 650 buf->ops->release(pipe, buf);
1da177e4 651 }
923f4f23
IM
652 if (pipe->tmp_page)
653 __free_page(pipe->tmp_page);
35f3d14d 654 kfree(pipe->bufs);
923f4f23 655 kfree(pipe);
1da177e4
LT
656}
657
fa3536cc 658static struct vfsmount *pipe_mnt __read_mostly;
341b446b 659
c23fbb6b
ED
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]",
75c3cfa8 666 d_inode(dentry)->i_ino);
c23fbb6b
ED
667}
668
3ba13d17 669static const struct dentry_operations pipefs_dentry_operations = {
c23fbb6b 670 .d_dname = pipefs_dname,
1da177e4
LT
671};
672
673static struct inode * get_pipe_inode(void)
674{
a209dfc7 675 struct inode *inode = new_inode_pseudo(pipe_mnt->mnt_sb);
923f4f23 676 struct pipe_inode_info *pipe;
1da177e4
LT
677
678 if (!inode)
679 goto fail_inode;
680
85fe4025
CH
681 inode->i_ino = get_next_ino();
682
7bee130e 683 pipe = alloc_pipe_info();
923f4f23 684 if (!pipe)
1da177e4 685 goto fail_iput;
3a326a2c 686
ba5bb147
AV
687 inode->i_pipe = pipe;
688 pipe->files = 2;
923f4f23 689 pipe->readers = pipe->writers = 1;
599a0ac1 690 inode->i_fop = &pipefifo_fops;
1da177e4
LT
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;
da9592ed
DH
700 inode->i_uid = current_fsuid();
701 inode->i_gid = current_fsgid();
1da177e4 702 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
923f4f23 703
1da177e4
LT
704 return inode;
705
706fail_iput:
707 iput(inode);
341b446b 708
1da177e4
LT
709fail_inode:
710 return NULL;
711}
712
e4fad8e5 713int create_pipe_files(struct file **res, int flags)
1da177e4 714{
d6cbd281 715 int err;
e4fad8e5 716 struct inode *inode = get_pipe_inode();
d6cbd281 717 struct file *f;
2c48b9c4 718 struct path path;
e4fad8e5 719 static struct qstr name = { .name = "" };
1da177e4 720
1da177e4 721 if (!inode)
e4fad8e5 722 return -ENFILE;
1da177e4 723
d6cbd281 724 err = -ENOMEM;
4b936885 725 path.dentry = d_alloc_pseudo(pipe_mnt->mnt_sb, &name);
2c48b9c4 726 if (!path.dentry)
d6cbd281 727 goto err_inode;
2c48b9c4 728 path.mnt = mntget(pipe_mnt);
341b446b 729
2c48b9c4 730 d_instantiate(path.dentry, inode);
430e285e 731
599a0ac1 732 f = alloc_file(&path, FMODE_WRITE, &pipefifo_fops);
e9bb1f9b
EB
733 if (IS_ERR(f)) {
734 err = PTR_ERR(f);
430e285e 735 goto err_dentry;
e9bb1f9b 736 }
341b446b 737
9883035a 738 f->f_flags = O_WRONLY | (flags & (O_NONBLOCK | O_DIRECT));
de32ec4c 739 f->private_data = inode->i_pipe;
d6cbd281 740
599a0ac1 741 res[0] = alloc_file(&path, FMODE_READ, &pipefifo_fops);
e9bb1f9b
EB
742 if (IS_ERR(res[0])) {
743 err = PTR_ERR(res[0]);
e4fad8e5 744 goto err_file;
e9bb1f9b 745 }
e4fad8e5
AV
746
747 path_get(&path);
de32ec4c 748 res[0]->private_data = inode->i_pipe;
e4fad8e5
AV
749 res[0]->f_flags = O_RDONLY | (flags & O_NONBLOCK);
750 res[1] = f;
751 return 0;
1da177e4 752
e4fad8e5
AV
753err_file:
754 put_filp(f);
755err_dentry:
4b8a8f1e 756 free_pipe_info(inode->i_pipe);
2c48b9c4 757 path_put(&path);
e4fad8e5 758 return err;
ed152437 759
e4fad8e5 760err_inode:
4b8a8f1e 761 free_pipe_info(inode->i_pipe);
1da177e4 762 iput(inode);
e4fad8e5 763 return err;
d6cbd281
AK
764}
765
5b249b1b 766static int __do_pipe_flags(int *fd, struct file **files, int flags)
d6cbd281 767{
d6cbd281
AK
768 int error;
769 int fdw, fdr;
770
9883035a 771 if (flags & ~(O_CLOEXEC | O_NONBLOCK | O_DIRECT))
ed8cae8b
UD
772 return -EINVAL;
773
e4fad8e5
AV
774 error = create_pipe_files(files, flags);
775 if (error)
776 return error;
d6cbd281 777
ed8cae8b 778 error = get_unused_fd_flags(flags);
d6cbd281
AK
779 if (error < 0)
780 goto err_read_pipe;
781 fdr = error;
782
ed8cae8b 783 error = get_unused_fd_flags(flags);
d6cbd281
AK
784 if (error < 0)
785 goto err_fdr;
786 fdw = error;
787
157cf649 788 audit_fd_pair(fdr, fdw);
d6cbd281
AK
789 fd[0] = fdr;
790 fd[1] = fdw;
d6cbd281
AK
791 return 0;
792
793 err_fdr:
794 put_unused_fd(fdr);
795 err_read_pipe:
e4fad8e5
AV
796 fput(files[0]);
797 fput(files[1]);
d6cbd281 798 return error;
1da177e4
LT
799}
800
5b249b1b
AV
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
d35c7b0e
UD
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 */
d4e82042 816SYSCALL_DEFINE2(pipe2, int __user *, fildes, int, flags)
d35c7b0e 817{
5b249b1b 818 struct file *files[2];
d35c7b0e
UD
819 int fd[2];
820 int error;
821
5b249b1b 822 error = __do_pipe_flags(fd, files, flags);
d35c7b0e 823 if (!error) {
5b249b1b
AV
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]);
d35c7b0e 829 error = -EFAULT;
5b249b1b
AV
830 } else {
831 fd_install(fd[0], files[0]);
832 fd_install(fd[1], files[1]);
ba719bae 833 }
d35c7b0e
UD
834 }
835 return error;
836}
837
2b664219 838SYSCALL_DEFINE1(pipe, int __user *, fildes)
ed8cae8b
UD
839{
840 return sys_pipe2(fildes, 0);
841}
842
fc7478a2 843static int wait_for_partner(struct pipe_inode_info *pipe, unsigned int *cnt)
f776c738
AV
844{
845 int cur = *cnt;
846
847 while (cur == *cnt) {
fc7478a2 848 pipe_wait(pipe);
f776c738
AV
849 if (signal_pending(current))
850 break;
851 }
852 return cur == *cnt ? -ERESTARTSYS : 0;
853}
854
fc7478a2 855static void wake_up_partner(struct pipe_inode_info *pipe)
f776c738 856{
fc7478a2 857 wake_up_interruptible(&pipe->wait);
f776c738
AV
858}
859
860static int fifo_open(struct inode *inode, struct file *filp)
861{
862 struct pipe_inode_info *pipe;
599a0ac1 863 bool is_pipe = inode->i_sb->s_magic == PIPEFS_MAGIC;
f776c738
AV
864 int ret;
865
ba5bb147
AV
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);
7bee130e 875 pipe = alloc_pipe_info();
f776c738 876 if (!pipe)
ba5bb147
AV
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);
4b8a8f1e 883 free_pipe_info(pipe);
ba5bb147
AV
884 pipe = inode->i_pipe;
885 } else {
886 inode->i_pipe = pipe;
887 spin_unlock(&inode->i_lock);
888 }
f776c738 889 }
de32ec4c 890 filp->private_data = pipe;
ba5bb147
AV
891 /* OK, we have a pipe and it's pinned down */
892
ebec73f4 893 __pipe_lock(pipe);
f776c738
AV
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 */
f776c738
AV
905 pipe->r_counter++;
906 if (pipe->readers++ == 0)
fc7478a2 907 wake_up_partner(pipe);
f776c738 908
599a0ac1 909 if (!is_pipe && !pipe->writers) {
f776c738
AV
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 {
fc7478a2 915 if (wait_for_partner(pipe, &pipe->w_counter))
f776c738
AV
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;
599a0ac1 928 if (!is_pipe && (filp->f_flags & O_NONBLOCK) && !pipe->readers)
f776c738
AV
929 goto err;
930
f776c738
AV
931 pipe->w_counter++;
932 if (!pipe->writers++)
fc7478a2 933 wake_up_partner(pipe);
f776c738 934
599a0ac1 935 if (!is_pipe && !pipe->readers) {
fc7478a2 936 if (wait_for_partner(pipe, &pipe->r_counter))
f776c738
AV
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 */
f776c738
AV
948
949 pipe->readers++;
950 pipe->writers++;
951 pipe->r_counter++;
952 pipe->w_counter++;
953 if (pipe->readers == 1 || pipe->writers == 1)
fc7478a2 954 wake_up_partner(pipe);
f776c738
AV
955 break;
956
957 default:
958 ret = -EINVAL;
959 goto err;
960 }
961
962 /* Ok! */
ebec73f4 963 __pipe_unlock(pipe);
f776c738
AV
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:
ebec73f4 979 __pipe_unlock(pipe);
b0d8d229
LT
980
981 put_pipe_info(inode, pipe);
f776c738
AV
982 return ret;
983}
984
599a0ac1
AV
985const struct file_operations pipefifo_fops = {
986 .open = fifo_open,
987 .llseek = no_llseek,
fb9096a3 988 .read_iter = pipe_read,
f0d1bec9 989 .write_iter = pipe_write,
599a0ac1
AV
990 .poll = pipe_poll,
991 .unlocked_ioctl = pipe_ioctl,
992 .release = pipe_release,
993 .fasync = pipe_fasync,
f776c738
AV
994};
995
35f3d14d
JA
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 */
b9598db3 1000static long pipe_set_size(struct pipe_inode_info *pipe, unsigned long nr_pages)
35f3d14d
JA
1001{
1002 struct pipe_buffer *bufs;
1003
35f3d14d
JA
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 */
b9598db3 1010 if (nr_pages < pipe->nrbufs)
35f3d14d
JA
1011 return -EBUSY;
1012
2ccd4f4d 1013 bufs = kcalloc(nr_pages, sizeof(*bufs), GFP_KERNEL | __GFP_NOWARN);
35f3d14d
JA
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) {
1d862f41
MS
1022 unsigned int tail;
1023 unsigned int head;
35f3d14d 1024
1d862f41
MS
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;
35f3d14d
JA
1032 if (head)
1033 memcpy(bufs, pipe->bufs + pipe->curbuf, head * sizeof(struct pipe_buffer));
1034 if (tail)
1d862f41 1035 memcpy(bufs + head, pipe->bufs, tail * sizeof(struct pipe_buffer));
35f3d14d
JA
1036 }
1037
759c0114 1038 account_pipe_buffers(pipe, pipe->buffers, nr_pages);
35f3d14d
JA
1039 pipe->curbuf = 0;
1040 kfree(pipe->bufs);
1041 pipe->bufs = bufs;
b9598db3
JA
1042 pipe->buffers = nr_pages;
1043 return nr_pages * PAGE_SIZE;
35f3d14d
JA
1044}
1045
ff9da691
JA
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
72083646
LT
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{
de32ec4c 1082 return file->f_op == &pipefifo_fops ? file->private_data : NULL;
72083646
LT
1083}
1084
35f3d14d
JA
1085long pipe_fcntl(struct file *file, unsigned int cmd, unsigned long arg)
1086{
1087 struct pipe_inode_info *pipe;
1088 long ret;
1089
c66fb347 1090 pipe = get_pipe_info(file);
35f3d14d
JA
1091 if (!pipe)
1092 return -EBADF;
1093
ebec73f4 1094 __pipe_lock(pipe);
35f3d14d
JA
1095
1096 switch (cmd) {
b9598db3 1097 case F_SETPIPE_SZ: {
ff9da691 1098 unsigned int size, nr_pages;
b9598db3 1099
ff9da691
JA
1100 size = round_pipe_size(arg);
1101 nr_pages = size >> PAGE_SHIFT;
b9598db3 1102
6db40cf0
MS
1103 ret = -EINVAL;
1104 if (!nr_pages)
1105 goto out;
1106
ff9da691 1107 if (!capable(CAP_SYS_RESOURCE) && size > pipe_max_size) {
b4ca7615 1108 ret = -EPERM;
cc967be5 1109 goto out;
759c0114
WT
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;
cc967be5 1115 }
ff9da691 1116 ret = pipe_set_size(pipe, nr_pages);
35f3d14d 1117 break;
b9598db3 1118 }
35f3d14d 1119 case F_GETPIPE_SZ:
b9598db3 1120 ret = pipe->buffers * PAGE_SIZE;
35f3d14d
JA
1121 break;
1122 default:
1123 ret = -EINVAL;
1124 break;
1125 }
1126
cc967be5 1127out:
ebec73f4 1128 __pipe_unlock(pipe);
35f3d14d
JA
1129 return ret;
1130}
1131
ff0c7d15
NP
1132static const struct super_operations pipefs_ops = {
1133 .destroy_inode = free_inode_nonrcu,
d70ef97b 1134 .statfs = simple_statfs,
ff0c7d15
NP
1135};
1136
1da177e4
LT
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 */
51139ada
AV
1143static struct dentry *pipefs_mount(struct file_system_type *fs_type,
1144 int flags, const char *dev_name, void *data)
1da177e4 1145{
c74a1cbb
AV
1146 return mount_pseudo(fs_type, "pipe:", &pipefs_ops,
1147 &pipefs_dentry_operations, PIPEFS_MAGIC);
1da177e4
LT
1148}
1149
1150static struct file_system_type pipe_fs_type = {
1151 .name = "pipefs",
51139ada 1152 .mount = pipefs_mount,
1da177e4
LT
1153 .kill_sb = kill_anon_super,
1154};
1155
1156static int __init init_pipe_fs(void)
1157{
1158 int err = register_filesystem(&pipe_fs_type);
341b446b 1159
1da177e4
LT
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
1da177e4 1170fs_initcall(init_pipe_fs);