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1 | // SPDX-License-Identifier: GPL-2.0 | |
2 | /* | |
3 | * linux/fs/pipe.c | |
4 | * | |
5 | * Copyright (C) 1991, 1992, 1999 Linus Torvalds | |
6 | */ | |
7 | ||
8 | #include <linux/mm.h> | |
9 | #include <linux/file.h> | |
10 | #include <linux/poll.h> | |
11 | #include <linux/slab.h> | |
12 | #include <linux/module.h> | |
13 | #include <linux/init.h> | |
14 | #include <linux/fs.h> | |
15 | #include <linux/log2.h> | |
16 | #include <linux/mount.h> | |
17 | #include <linux/pseudo_fs.h> | |
18 | #include <linux/magic.h> | |
19 | #include <linux/pipe_fs_i.h> | |
20 | #include <linux/uio.h> | |
21 | #include <linux/highmem.h> | |
22 | #include <linux/pagemap.h> | |
23 | #include <linux/audit.h> | |
24 | #include <linux/syscalls.h> | |
25 | #include <linux/fcntl.h> | |
26 | #include <linux/memcontrol.h> | |
27 | ||
28 | #include <linux/uaccess.h> | |
29 | #include <asm/ioctls.h> | |
30 | ||
31 | #include "internal.h" | |
32 | ||
33 | /* | |
34 | * The max size that a non-root user is allowed to grow the pipe. Can | |
35 | * be set by root in /proc/sys/fs/pipe-max-size | |
36 | */ | |
37 | unsigned int pipe_max_size = 1048576; | |
38 | ||
39 | /* Maximum allocatable pages per user. Hard limit is unset by default, soft | |
40 | * matches default values. | |
41 | */ | |
42 | unsigned long pipe_user_pages_hard; | |
43 | unsigned long pipe_user_pages_soft = PIPE_DEF_BUFFERS * INR_OPEN_CUR; | |
44 | ||
45 | /* | |
46 | * We use head and tail indices that aren't masked off, except at the point of | |
47 | * dereference, but rather they're allowed to wrap naturally. This means there | |
48 | * isn't a dead spot in the buffer, but the ring has to be a power of two and | |
49 | * <= 2^31. | |
50 | * -- David Howells 2019-09-23. | |
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 | ||
62 | static 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 | ||
68 | void 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 | } | |
75 | EXPORT_SYMBOL(pipe_lock); | |
76 | ||
77 | void pipe_unlock(struct pipe_inode_info *pipe) | |
78 | { | |
79 | if (pipe->files) | |
80 | mutex_unlock(&pipe->mutex); | |
81 | } | |
82 | EXPORT_SYMBOL(pipe_unlock); | |
83 | ||
84 | static inline void __pipe_lock(struct pipe_inode_info *pipe) | |
85 | { | |
86 | mutex_lock_nested(&pipe->mutex, I_MUTEX_PARENT); | |
87 | } | |
88 | ||
89 | static inline void __pipe_unlock(struct pipe_inode_info *pipe) | |
90 | { | |
91 | mutex_unlock(&pipe->mutex); | |
92 | } | |
93 | ||
94 | void 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 */ | |
109 | void 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 | ||
124 | static 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 | static int anon_pipe_buf_steal(struct pipe_inode_info *pipe, | |
141 | struct pipe_buffer *buf) | |
142 | { | |
143 | struct page *page = buf->page; | |
144 | ||
145 | if (page_count(page) == 1) { | |
146 | memcg_kmem_uncharge(page, 0); | |
147 | __SetPageLocked(page); | |
148 | return 0; | |
149 | } | |
150 | return 1; | |
151 | } | |
152 | ||
153 | /** | |
154 | * generic_pipe_buf_steal - attempt to take ownership of a &pipe_buffer | |
155 | * @pipe: the pipe that the buffer belongs to | |
156 | * @buf: the buffer to attempt to steal | |
157 | * | |
158 | * Description: | |
159 | * This function attempts to steal the &struct page attached to | |
160 | * @buf. If successful, this function returns 0 and returns with | |
161 | * the page locked. The caller may then reuse the page for whatever | |
162 | * he wishes; the typical use is insertion into a different file | |
163 | * page cache. | |
164 | */ | |
165 | int generic_pipe_buf_steal(struct pipe_inode_info *pipe, | |
166 | struct pipe_buffer *buf) | |
167 | { | |
168 | struct page *page = buf->page; | |
169 | ||
170 | /* | |
171 | * A reference of one is golden, that means that the owner of this | |
172 | * page is the only one holding a reference to it. lock the page | |
173 | * and return OK. | |
174 | */ | |
175 | if (page_count(page) == 1) { | |
176 | lock_page(page); | |
177 | return 0; | |
178 | } | |
179 | ||
180 | return 1; | |
181 | } | |
182 | EXPORT_SYMBOL(generic_pipe_buf_steal); | |
183 | ||
184 | /** | |
185 | * generic_pipe_buf_get - get a reference to a &struct pipe_buffer | |
186 | * @pipe: the pipe that the buffer belongs to | |
187 | * @buf: the buffer to get a reference to | |
188 | * | |
189 | * Description: | |
190 | * This function grabs an extra reference to @buf. It's used in | |
191 | * in the tee() system call, when we duplicate the buffers in one | |
192 | * pipe into another. | |
193 | */ | |
194 | bool generic_pipe_buf_get(struct pipe_inode_info *pipe, struct pipe_buffer *buf) | |
195 | { | |
196 | return try_get_page(buf->page); | |
197 | } | |
198 | EXPORT_SYMBOL(generic_pipe_buf_get); | |
199 | ||
200 | /** | |
201 | * generic_pipe_buf_confirm - verify contents of the pipe buffer | |
202 | * @info: the pipe that the buffer belongs to | |
203 | * @buf: the buffer to confirm | |
204 | * | |
205 | * Description: | |
206 | * This function does nothing, because the generic pipe code uses | |
207 | * pages that are always good when inserted into the pipe. | |
208 | */ | |
209 | int generic_pipe_buf_confirm(struct pipe_inode_info *info, | |
210 | struct pipe_buffer *buf) | |
211 | { | |
212 | return 0; | |
213 | } | |
214 | EXPORT_SYMBOL(generic_pipe_buf_confirm); | |
215 | ||
216 | /** | |
217 | * generic_pipe_buf_release - put a reference to a &struct pipe_buffer | |
218 | * @pipe: the pipe that the buffer belongs to | |
219 | * @buf: the buffer to put a reference to | |
220 | * | |
221 | * Description: | |
222 | * This function releases a reference to @buf. | |
223 | */ | |
224 | void generic_pipe_buf_release(struct pipe_inode_info *pipe, | |
225 | struct pipe_buffer *buf) | |
226 | { | |
227 | put_page(buf->page); | |
228 | } | |
229 | EXPORT_SYMBOL(generic_pipe_buf_release); | |
230 | ||
231 | /* New data written to a pipe may be appended to a buffer with this type. */ | |
232 | static const struct pipe_buf_operations anon_pipe_buf_ops = { | |
233 | .confirm = generic_pipe_buf_confirm, | |
234 | .release = anon_pipe_buf_release, | |
235 | .steal = anon_pipe_buf_steal, | |
236 | .get = generic_pipe_buf_get, | |
237 | }; | |
238 | ||
239 | static const struct pipe_buf_operations anon_pipe_buf_nomerge_ops = { | |
240 | .confirm = generic_pipe_buf_confirm, | |
241 | .release = anon_pipe_buf_release, | |
242 | .steal = anon_pipe_buf_steal, | |
243 | .get = generic_pipe_buf_get, | |
244 | }; | |
245 | ||
246 | static const struct pipe_buf_operations packet_pipe_buf_ops = { | |
247 | .confirm = generic_pipe_buf_confirm, | |
248 | .release = anon_pipe_buf_release, | |
249 | .steal = anon_pipe_buf_steal, | |
250 | .get = generic_pipe_buf_get, | |
251 | }; | |
252 | ||
253 | /** | |
254 | * pipe_buf_mark_unmergeable - mark a &struct pipe_buffer as unmergeable | |
255 | * @buf: the buffer to mark | |
256 | * | |
257 | * Description: | |
258 | * This function ensures that no future writes will be merged into the | |
259 | * given &struct pipe_buffer. This is necessary when multiple pipe buffers | |
260 | * share the same backing page. | |
261 | */ | |
262 | void pipe_buf_mark_unmergeable(struct pipe_buffer *buf) | |
263 | { | |
264 | if (buf->ops == &anon_pipe_buf_ops) | |
265 | buf->ops = &anon_pipe_buf_nomerge_ops; | |
266 | } | |
267 | ||
268 | static bool pipe_buf_can_merge(struct pipe_buffer *buf) | |
269 | { | |
270 | return buf->ops == &anon_pipe_buf_ops; | |
271 | } | |
272 | ||
273 | /* Done while waiting without holding the pipe lock - thus the READ_ONCE() */ | |
274 | static inline bool pipe_readable(const struct pipe_inode_info *pipe) | |
275 | { | |
276 | unsigned int head = READ_ONCE(pipe->head); | |
277 | unsigned int tail = READ_ONCE(pipe->tail); | |
278 | unsigned int writers = READ_ONCE(pipe->writers); | |
279 | ||
280 | return !pipe_empty(head, tail) || !writers; | |
281 | } | |
282 | ||
283 | static ssize_t | |
284 | pipe_read(struct kiocb *iocb, struct iov_iter *to) | |
285 | { | |
286 | size_t total_len = iov_iter_count(to); | |
287 | struct file *filp = iocb->ki_filp; | |
288 | struct pipe_inode_info *pipe = filp->private_data; | |
289 | bool was_full; | |
290 | ssize_t ret; | |
291 | ||
292 | /* Null read succeeds. */ | |
293 | if (unlikely(total_len == 0)) | |
294 | return 0; | |
295 | ||
296 | ret = 0; | |
297 | __pipe_lock(pipe); | |
298 | ||
299 | /* | |
300 | * We only wake up writers if the pipe was full when we started | |
301 | * reading in order to avoid unnecessary wakeups. | |
302 | * | |
303 | * But when we do wake up writers, we do so using a sync wakeup | |
304 | * (WF_SYNC), because we want them to get going and generate more | |
305 | * data for us. | |
306 | */ | |
307 | was_full = pipe_full(pipe->head, pipe->tail, pipe->max_usage); | |
308 | for (;;) { | |
309 | unsigned int head = pipe->head; | |
310 | unsigned int tail = pipe->tail; | |
311 | unsigned int mask = pipe->ring_size - 1; | |
312 | ||
313 | if (!pipe_empty(head, tail)) { | |
314 | struct pipe_buffer *buf = &pipe->bufs[tail & mask]; | |
315 | size_t chars = buf->len; | |
316 | size_t written; | |
317 | int error; | |
318 | ||
319 | if (chars > total_len) | |
320 | chars = total_len; | |
321 | ||
322 | error = pipe_buf_confirm(pipe, buf); | |
323 | if (error) { | |
324 | if (!ret) | |
325 | ret = error; | |
326 | break; | |
327 | } | |
328 | ||
329 | written = copy_page_to_iter(buf->page, buf->offset, chars, to); | |
330 | if (unlikely(written < chars)) { | |
331 | if (!ret) | |
332 | ret = -EFAULT; | |
333 | break; | |
334 | } | |
335 | ret += chars; | |
336 | buf->offset += chars; | |
337 | buf->len -= chars; | |
338 | ||
339 | /* Was it a packet buffer? Clean up and exit */ | |
340 | if (buf->flags & PIPE_BUF_FLAG_PACKET) { | |
341 | total_len = chars; | |
342 | buf->len = 0; | |
343 | } | |
344 | ||
345 | if (!buf->len) { | |
346 | pipe_buf_release(pipe, buf); | |
347 | spin_lock_irq(&pipe->wait.lock); | |
348 | tail++; | |
349 | pipe->tail = tail; | |
350 | spin_unlock_irq(&pipe->wait.lock); | |
351 | } | |
352 | total_len -= chars; | |
353 | if (!total_len) | |
354 | break; /* common path: read succeeded */ | |
355 | if (!pipe_empty(head, tail)) /* More to do? */ | |
356 | continue; | |
357 | } | |
358 | ||
359 | if (!pipe->writers) | |
360 | break; | |
361 | if (ret) | |
362 | break; | |
363 | if (filp->f_flags & O_NONBLOCK) { | |
364 | ret = -EAGAIN; | |
365 | break; | |
366 | } | |
367 | __pipe_unlock(pipe); | |
368 | ||
369 | /* | |
370 | * We only get here if we didn't actually read anything. | |
371 | * | |
372 | * However, we could have seen (and removed) a zero-sized | |
373 | * pipe buffer, and might have made space in the buffers | |
374 | * that way. | |
375 | * | |
376 | * You can't make zero-sized pipe buffers by doing an empty | |
377 | * write (not even in packet mode), but they can happen if | |
378 | * the writer gets an EFAULT when trying to fill a buffer | |
379 | * that already got allocated and inserted in the buffer | |
380 | * array. | |
381 | * | |
382 | * So we still need to wake up any pending writers in the | |
383 | * _very_ unlikely case that the pipe was full, but we got | |
384 | * no data. | |
385 | */ | |
386 | if (unlikely(was_full)) { | |
387 | wake_up_interruptible_sync_poll(&pipe->wait, EPOLLOUT | EPOLLWRNORM); | |
388 | kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT); | |
389 | } | |
390 | ||
391 | /* | |
392 | * But because we didn't read anything, at this point we can | |
393 | * just return directly with -ERESTARTSYS if we're interrupted, | |
394 | * since we've done any required wakeups and there's no need | |
395 | * to mark anything accessed. And we've dropped the lock. | |
396 | */ | |
397 | if (wait_event_interruptible(pipe->wait, pipe_readable(pipe)) < 0) | |
398 | return -ERESTARTSYS; | |
399 | ||
400 | __pipe_lock(pipe); | |
401 | was_full = pipe_full(pipe->head, pipe->tail, pipe->max_usage); | |
402 | } | |
403 | __pipe_unlock(pipe); | |
404 | ||
405 | if (was_full) { | |
406 | wake_up_interruptible_sync_poll(&pipe->wait, EPOLLOUT | EPOLLWRNORM); | |
407 | kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT); | |
408 | } | |
409 | if (ret > 0) | |
410 | file_accessed(filp); | |
411 | return ret; | |
412 | } | |
413 | ||
414 | static inline int is_packetized(struct file *file) | |
415 | { | |
416 | return (file->f_flags & O_DIRECT) != 0; | |
417 | } | |
418 | ||
419 | /* Done while waiting without holding the pipe lock - thus the READ_ONCE() */ | |
420 | static inline bool pipe_writable(const struct pipe_inode_info *pipe) | |
421 | { | |
422 | unsigned int head = READ_ONCE(pipe->head); | |
423 | unsigned int tail = READ_ONCE(pipe->tail); | |
424 | unsigned int max_usage = READ_ONCE(pipe->max_usage); | |
425 | ||
426 | return !pipe_full(head, tail, max_usage) || | |
427 | !READ_ONCE(pipe->readers); | |
428 | } | |
429 | ||
430 | static ssize_t | |
431 | pipe_write(struct kiocb *iocb, struct iov_iter *from) | |
432 | { | |
433 | struct file *filp = iocb->ki_filp; | |
434 | struct pipe_inode_info *pipe = filp->private_data; | |
435 | unsigned int head; | |
436 | ssize_t ret = 0; | |
437 | size_t total_len = iov_iter_count(from); | |
438 | ssize_t chars; | |
439 | bool was_empty = false; | |
440 | ||
441 | /* Null write succeeds. */ | |
442 | if (unlikely(total_len == 0)) | |
443 | return 0; | |
444 | ||
445 | __pipe_lock(pipe); | |
446 | ||
447 | if (!pipe->readers) { | |
448 | send_sig(SIGPIPE, current, 0); | |
449 | ret = -EPIPE; | |
450 | goto out; | |
451 | } | |
452 | ||
453 | /* | |
454 | * Only wake up if the pipe started out empty, since | |
455 | * otherwise there should be no readers waiting. | |
456 | * | |
457 | * If it wasn't empty we try to merge new data into | |
458 | * the last buffer. | |
459 | * | |
460 | * That naturally merges small writes, but it also | |
461 | * page-aligs the rest of the writes for large writes | |
462 | * spanning multiple pages. | |
463 | */ | |
464 | head = pipe->head; | |
465 | was_empty = pipe_empty(head, pipe->tail); | |
466 | chars = total_len & (PAGE_SIZE-1); | |
467 | if (chars && !was_empty) { | |
468 | unsigned int mask = pipe->ring_size - 1; | |
469 | struct pipe_buffer *buf = &pipe->bufs[(head - 1) & mask]; | |
470 | int offset = buf->offset + buf->len; | |
471 | ||
472 | if (pipe_buf_can_merge(buf) && offset + chars <= PAGE_SIZE) { | |
473 | ret = pipe_buf_confirm(pipe, buf); | |
474 | if (ret) | |
475 | goto out; | |
476 | ||
477 | ret = copy_page_from_iter(buf->page, offset, chars, from); | |
478 | if (unlikely(ret < chars)) { | |
479 | ret = -EFAULT; | |
480 | goto out; | |
481 | } | |
482 | ||
483 | buf->len += ret; | |
484 | if (!iov_iter_count(from)) | |
485 | goto out; | |
486 | } | |
487 | } | |
488 | ||
489 | for (;;) { | |
490 | if (!pipe->readers) { | |
491 | send_sig(SIGPIPE, current, 0); | |
492 | if (!ret) | |
493 | ret = -EPIPE; | |
494 | break; | |
495 | } | |
496 | ||
497 | head = pipe->head; | |
498 | if (!pipe_full(head, pipe->tail, pipe->max_usage)) { | |
499 | unsigned int mask = pipe->ring_size - 1; | |
500 | struct pipe_buffer *buf = &pipe->bufs[head & mask]; | |
501 | struct page *page = pipe->tmp_page; | |
502 | int copied; | |
503 | ||
504 | if (!page) { | |
505 | page = alloc_page(GFP_HIGHUSER | __GFP_ACCOUNT); | |
506 | if (unlikely(!page)) { | |
507 | ret = ret ? : -ENOMEM; | |
508 | break; | |
509 | } | |
510 | pipe->tmp_page = page; | |
511 | } | |
512 | ||
513 | /* Allocate a slot in the ring in advance and attach an | |
514 | * empty buffer. If we fault or otherwise fail to use | |
515 | * it, either the reader will consume it or it'll still | |
516 | * be there for the next write. | |
517 | */ | |
518 | spin_lock_irq(&pipe->wait.lock); | |
519 | ||
520 | head = pipe->head; | |
521 | if (pipe_full(head, pipe->tail, pipe->max_usage)) { | |
522 | spin_unlock_irq(&pipe->wait.lock); | |
523 | continue; | |
524 | } | |
525 | ||
526 | pipe->head = head + 1; | |
527 | spin_unlock_irq(&pipe->wait.lock); | |
528 | ||
529 | /* Insert it into the buffer array */ | |
530 | buf = &pipe->bufs[head & mask]; | |
531 | buf->page = page; | |
532 | buf->ops = &anon_pipe_buf_ops; | |
533 | buf->offset = 0; | |
534 | buf->len = 0; | |
535 | buf->flags = 0; | |
536 | if (is_packetized(filp)) { | |
537 | buf->ops = &packet_pipe_buf_ops; | |
538 | buf->flags = PIPE_BUF_FLAG_PACKET; | |
539 | } | |
540 | pipe->tmp_page = NULL; | |
541 | ||
542 | copied = copy_page_from_iter(page, 0, PAGE_SIZE, from); | |
543 | if (unlikely(copied < PAGE_SIZE && iov_iter_count(from))) { | |
544 | if (!ret) | |
545 | ret = -EFAULT; | |
546 | break; | |
547 | } | |
548 | ret += copied; | |
549 | buf->offset = 0; | |
550 | buf->len = copied; | |
551 | ||
552 | if (!iov_iter_count(from)) | |
553 | break; | |
554 | } | |
555 | ||
556 | if (!pipe_full(head, pipe->tail, pipe->max_usage)) | |
557 | continue; | |
558 | ||
559 | /* Wait for buffer space to become available. */ | |
560 | if (filp->f_flags & O_NONBLOCK) { | |
561 | if (!ret) | |
562 | ret = -EAGAIN; | |
563 | break; | |
564 | } | |
565 | if (signal_pending(current)) { | |
566 | if (!ret) | |
567 | ret = -ERESTARTSYS; | |
568 | break; | |
569 | } | |
570 | ||
571 | /* | |
572 | * We're going to release the pipe lock and wait for more | |
573 | * space. We wake up any readers if necessary, and then | |
574 | * after waiting we need to re-check whether the pipe | |
575 | * become empty while we dropped the lock. | |
576 | */ | |
577 | __pipe_unlock(pipe); | |
578 | if (was_empty) { | |
579 | wake_up_interruptible_sync_poll(&pipe->wait, EPOLLIN | EPOLLRDNORM); | |
580 | kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN); | |
581 | } | |
582 | wait_event_interruptible(pipe->wait, pipe_writable(pipe)); | |
583 | __pipe_lock(pipe); | |
584 | was_empty = pipe_empty(pipe->head, pipe->tail); | |
585 | } | |
586 | out: | |
587 | __pipe_unlock(pipe); | |
588 | ||
589 | /* | |
590 | * If we do do a wakeup event, we do a 'sync' wakeup, because we | |
591 | * want the reader to start processing things asap, rather than | |
592 | * leave the data pending. | |
593 | * | |
594 | * This is particularly important for small writes, because of | |
595 | * how (for example) the GNU make jobserver uses small writes to | |
596 | * wake up pending jobs | |
597 | */ | |
598 | if (was_empty) { | |
599 | wake_up_interruptible_sync_poll(&pipe->wait, EPOLLIN | EPOLLRDNORM); | |
600 | kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN); | |
601 | } | |
602 | if (ret > 0 && sb_start_write_trylock(file_inode(filp)->i_sb)) { | |
603 | int err = file_update_time(filp); | |
604 | if (err) | |
605 | ret = err; | |
606 | sb_end_write(file_inode(filp)->i_sb); | |
607 | } | |
608 | return ret; | |
609 | } | |
610 | ||
611 | static long pipe_ioctl(struct file *filp, unsigned int cmd, unsigned long arg) | |
612 | { | |
613 | struct pipe_inode_info *pipe = filp->private_data; | |
614 | int count, head, tail, mask; | |
615 | ||
616 | switch (cmd) { | |
617 | case FIONREAD: | |
618 | __pipe_lock(pipe); | |
619 | count = 0; | |
620 | head = pipe->head; | |
621 | tail = pipe->tail; | |
622 | mask = pipe->ring_size - 1; | |
623 | ||
624 | while (tail != head) { | |
625 | count += pipe->bufs[tail & mask].len; | |
626 | tail++; | |
627 | } | |
628 | __pipe_unlock(pipe); | |
629 | ||
630 | return put_user(count, (int __user *)arg); | |
631 | default: | |
632 | return -ENOIOCTLCMD; | |
633 | } | |
634 | } | |
635 | ||
636 | /* No kernel lock held - fine */ | |
637 | static __poll_t | |
638 | pipe_poll(struct file *filp, poll_table *wait) | |
639 | { | |
640 | __poll_t mask; | |
641 | struct pipe_inode_info *pipe = filp->private_data; | |
642 | unsigned int head, tail; | |
643 | ||
644 | /* | |
645 | * Reading only -- no need for acquiring the semaphore. | |
646 | * | |
647 | * But because this is racy, the code has to add the | |
648 | * entry to the poll table _first_ .. | |
649 | */ | |
650 | poll_wait(filp, &pipe->wait, wait); | |
651 | ||
652 | /* | |
653 | * .. and only then can you do the racy tests. That way, | |
654 | * if something changes and you got it wrong, the poll | |
655 | * table entry will wake you up and fix it. | |
656 | */ | |
657 | head = READ_ONCE(pipe->head); | |
658 | tail = READ_ONCE(pipe->tail); | |
659 | ||
660 | mask = 0; | |
661 | if (filp->f_mode & FMODE_READ) { | |
662 | if (!pipe_empty(head, tail)) | |
663 | mask |= EPOLLIN | EPOLLRDNORM; | |
664 | if (!pipe->writers && filp->f_version != pipe->w_counter) | |
665 | mask |= EPOLLHUP; | |
666 | } | |
667 | ||
668 | if (filp->f_mode & FMODE_WRITE) { | |
669 | if (!pipe_full(head, tail, pipe->max_usage)) | |
670 | mask |= EPOLLOUT | EPOLLWRNORM; | |
671 | /* | |
672 | * Most Unices do not set EPOLLERR for FIFOs but on Linux they | |
673 | * behave exactly like pipes for poll(). | |
674 | */ | |
675 | if (!pipe->readers) | |
676 | mask |= EPOLLERR; | |
677 | } | |
678 | ||
679 | return mask; | |
680 | } | |
681 | ||
682 | static void put_pipe_info(struct inode *inode, struct pipe_inode_info *pipe) | |
683 | { | |
684 | int kill = 0; | |
685 | ||
686 | spin_lock(&inode->i_lock); | |
687 | if (!--pipe->files) { | |
688 | inode->i_pipe = NULL; | |
689 | kill = 1; | |
690 | } | |
691 | spin_unlock(&inode->i_lock); | |
692 | ||
693 | if (kill) | |
694 | free_pipe_info(pipe); | |
695 | } | |
696 | ||
697 | static int | |
698 | pipe_release(struct inode *inode, struct file *file) | |
699 | { | |
700 | struct pipe_inode_info *pipe = file->private_data; | |
701 | ||
702 | __pipe_lock(pipe); | |
703 | if (file->f_mode & FMODE_READ) | |
704 | pipe->readers--; | |
705 | if (file->f_mode & FMODE_WRITE) | |
706 | pipe->writers--; | |
707 | ||
708 | if (pipe->readers || pipe->writers) { | |
709 | wake_up_interruptible_sync_poll(&pipe->wait, EPOLLIN | EPOLLOUT | EPOLLRDNORM | EPOLLWRNORM | EPOLLERR | EPOLLHUP); | |
710 | kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN); | |
711 | kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT); | |
712 | } | |
713 | __pipe_unlock(pipe); | |
714 | ||
715 | put_pipe_info(inode, pipe); | |
716 | return 0; | |
717 | } | |
718 | ||
719 | static int | |
720 | pipe_fasync(int fd, struct file *filp, int on) | |
721 | { | |
722 | struct pipe_inode_info *pipe = filp->private_data; | |
723 | int retval = 0; | |
724 | ||
725 | __pipe_lock(pipe); | |
726 | if (filp->f_mode & FMODE_READ) | |
727 | retval = fasync_helper(fd, filp, on, &pipe->fasync_readers); | |
728 | if ((filp->f_mode & FMODE_WRITE) && retval >= 0) { | |
729 | retval = fasync_helper(fd, filp, on, &pipe->fasync_writers); | |
730 | if (retval < 0 && (filp->f_mode & FMODE_READ)) | |
731 | /* this can happen only if on == T */ | |
732 | fasync_helper(-1, filp, 0, &pipe->fasync_readers); | |
733 | } | |
734 | __pipe_unlock(pipe); | |
735 | return retval; | |
736 | } | |
737 | ||
738 | static unsigned long account_pipe_buffers(struct user_struct *user, | |
739 | unsigned long old, unsigned long new) | |
740 | { | |
741 | return atomic_long_add_return(new - old, &user->pipe_bufs); | |
742 | } | |
743 | ||
744 | static bool too_many_pipe_buffers_soft(unsigned long user_bufs) | |
745 | { | |
746 | unsigned long soft_limit = READ_ONCE(pipe_user_pages_soft); | |
747 | ||
748 | return soft_limit && user_bufs > soft_limit; | |
749 | } | |
750 | ||
751 | static bool too_many_pipe_buffers_hard(unsigned long user_bufs) | |
752 | { | |
753 | unsigned long hard_limit = READ_ONCE(pipe_user_pages_hard); | |
754 | ||
755 | return hard_limit && user_bufs > hard_limit; | |
756 | } | |
757 | ||
758 | static bool is_unprivileged_user(void) | |
759 | { | |
760 | return !capable(CAP_SYS_RESOURCE) && !capable(CAP_SYS_ADMIN); | |
761 | } | |
762 | ||
763 | struct pipe_inode_info *alloc_pipe_info(void) | |
764 | { | |
765 | struct pipe_inode_info *pipe; | |
766 | unsigned long pipe_bufs = PIPE_DEF_BUFFERS; | |
767 | struct user_struct *user = get_current_user(); | |
768 | unsigned long user_bufs; | |
769 | unsigned int max_size = READ_ONCE(pipe_max_size); | |
770 | ||
771 | pipe = kzalloc(sizeof(struct pipe_inode_info), GFP_KERNEL_ACCOUNT); | |
772 | if (pipe == NULL) | |
773 | goto out_free_uid; | |
774 | ||
775 | if (pipe_bufs * PAGE_SIZE > max_size && !capable(CAP_SYS_RESOURCE)) | |
776 | pipe_bufs = max_size >> PAGE_SHIFT; | |
777 | ||
778 | user_bufs = account_pipe_buffers(user, 0, pipe_bufs); | |
779 | ||
780 | if (too_many_pipe_buffers_soft(user_bufs) && is_unprivileged_user()) { | |
781 | user_bufs = account_pipe_buffers(user, pipe_bufs, 1); | |
782 | pipe_bufs = 1; | |
783 | } | |
784 | ||
785 | if (too_many_pipe_buffers_hard(user_bufs) && is_unprivileged_user()) | |
786 | goto out_revert_acct; | |
787 | ||
788 | pipe->bufs = kcalloc(pipe_bufs, sizeof(struct pipe_buffer), | |
789 | GFP_KERNEL_ACCOUNT); | |
790 | ||
791 | if (pipe->bufs) { | |
792 | init_waitqueue_head(&pipe->wait); | |
793 | pipe->r_counter = pipe->w_counter = 1; | |
794 | pipe->max_usage = pipe_bufs; | |
795 | pipe->ring_size = pipe_bufs; | |
796 | pipe->user = user; | |
797 | mutex_init(&pipe->mutex); | |
798 | return pipe; | |
799 | } | |
800 | ||
801 | out_revert_acct: | |
802 | (void) account_pipe_buffers(user, pipe_bufs, 0); | |
803 | kfree(pipe); | |
804 | out_free_uid: | |
805 | free_uid(user); | |
806 | return NULL; | |
807 | } | |
808 | ||
809 | void free_pipe_info(struct pipe_inode_info *pipe) | |
810 | { | |
811 | int i; | |
812 | ||
813 | (void) account_pipe_buffers(pipe->user, pipe->ring_size, 0); | |
814 | free_uid(pipe->user); | |
815 | for (i = 0; i < pipe->ring_size; i++) { | |
816 | struct pipe_buffer *buf = pipe->bufs + i; | |
817 | if (buf->ops) | |
818 | pipe_buf_release(pipe, buf); | |
819 | } | |
820 | if (pipe->tmp_page) | |
821 | __free_page(pipe->tmp_page); | |
822 | kfree(pipe->bufs); | |
823 | kfree(pipe); | |
824 | } | |
825 | ||
826 | static struct vfsmount *pipe_mnt __read_mostly; | |
827 | ||
828 | /* | |
829 | * pipefs_dname() is called from d_path(). | |
830 | */ | |
831 | static char *pipefs_dname(struct dentry *dentry, char *buffer, int buflen) | |
832 | { | |
833 | return dynamic_dname(dentry, buffer, buflen, "pipe:[%lu]", | |
834 | d_inode(dentry)->i_ino); | |
835 | } | |
836 | ||
837 | static const struct dentry_operations pipefs_dentry_operations = { | |
838 | .d_dname = pipefs_dname, | |
839 | }; | |
840 | ||
841 | static struct inode * get_pipe_inode(void) | |
842 | { | |
843 | struct inode *inode = new_inode_pseudo(pipe_mnt->mnt_sb); | |
844 | struct pipe_inode_info *pipe; | |
845 | ||
846 | if (!inode) | |
847 | goto fail_inode; | |
848 | ||
849 | inode->i_ino = get_next_ino(); | |
850 | ||
851 | pipe = alloc_pipe_info(); | |
852 | if (!pipe) | |
853 | goto fail_iput; | |
854 | ||
855 | inode->i_pipe = pipe; | |
856 | pipe->files = 2; | |
857 | pipe->readers = pipe->writers = 1; | |
858 | inode->i_fop = &pipefifo_fops; | |
859 | ||
860 | /* | |
861 | * Mark the inode dirty from the very beginning, | |
862 | * that way it will never be moved to the dirty | |
863 | * list because "mark_inode_dirty()" will think | |
864 | * that it already _is_ on the dirty list. | |
865 | */ | |
866 | inode->i_state = I_DIRTY; | |
867 | inode->i_mode = S_IFIFO | S_IRUSR | S_IWUSR; | |
868 | inode->i_uid = current_fsuid(); | |
869 | inode->i_gid = current_fsgid(); | |
870 | inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode); | |
871 | ||
872 | return inode; | |
873 | ||
874 | fail_iput: | |
875 | iput(inode); | |
876 | ||
877 | fail_inode: | |
878 | return NULL; | |
879 | } | |
880 | ||
881 | int create_pipe_files(struct file **res, int flags) | |
882 | { | |
883 | struct inode *inode = get_pipe_inode(); | |
884 | struct file *f; | |
885 | ||
886 | if (!inode) | |
887 | return -ENFILE; | |
888 | ||
889 | f = alloc_file_pseudo(inode, pipe_mnt, "", | |
890 | O_WRONLY | (flags & (O_NONBLOCK | O_DIRECT)), | |
891 | &pipefifo_fops); | |
892 | if (IS_ERR(f)) { | |
893 | free_pipe_info(inode->i_pipe); | |
894 | iput(inode); | |
895 | return PTR_ERR(f); | |
896 | } | |
897 | ||
898 | f->private_data = inode->i_pipe; | |
899 | ||
900 | res[0] = alloc_file_clone(f, O_RDONLY | (flags & O_NONBLOCK), | |
901 | &pipefifo_fops); | |
902 | if (IS_ERR(res[0])) { | |
903 | put_pipe_info(inode, inode->i_pipe); | |
904 | fput(f); | |
905 | return PTR_ERR(res[0]); | |
906 | } | |
907 | res[0]->private_data = inode->i_pipe; | |
908 | res[1] = f; | |
909 | stream_open(inode, res[0]); | |
910 | stream_open(inode, res[1]); | |
911 | return 0; | |
912 | } | |
913 | ||
914 | static int __do_pipe_flags(int *fd, struct file **files, int flags) | |
915 | { | |
916 | int error; | |
917 | int fdw, fdr; | |
918 | ||
919 | if (flags & ~(O_CLOEXEC | O_NONBLOCK | O_DIRECT)) | |
920 | return -EINVAL; | |
921 | ||
922 | error = create_pipe_files(files, flags); | |
923 | if (error) | |
924 | return error; | |
925 | ||
926 | error = get_unused_fd_flags(flags); | |
927 | if (error < 0) | |
928 | goto err_read_pipe; | |
929 | fdr = error; | |
930 | ||
931 | error = get_unused_fd_flags(flags); | |
932 | if (error < 0) | |
933 | goto err_fdr; | |
934 | fdw = error; | |
935 | ||
936 | audit_fd_pair(fdr, fdw); | |
937 | fd[0] = fdr; | |
938 | fd[1] = fdw; | |
939 | return 0; | |
940 | ||
941 | err_fdr: | |
942 | put_unused_fd(fdr); | |
943 | err_read_pipe: | |
944 | fput(files[0]); | |
945 | fput(files[1]); | |
946 | return error; | |
947 | } | |
948 | ||
949 | int do_pipe_flags(int *fd, int flags) | |
950 | { | |
951 | struct file *files[2]; | |
952 | int error = __do_pipe_flags(fd, files, flags); | |
953 | if (!error) { | |
954 | fd_install(fd[0], files[0]); | |
955 | fd_install(fd[1], files[1]); | |
956 | } | |
957 | return error; | |
958 | } | |
959 | ||
960 | /* | |
961 | * sys_pipe() is the normal C calling standard for creating | |
962 | * a pipe. It's not the way Unix traditionally does this, though. | |
963 | */ | |
964 | static int do_pipe2(int __user *fildes, int flags) | |
965 | { | |
966 | struct file *files[2]; | |
967 | int fd[2]; | |
968 | int error; | |
969 | ||
970 | error = __do_pipe_flags(fd, files, flags); | |
971 | if (!error) { | |
972 | if (unlikely(copy_to_user(fildes, fd, sizeof(fd)))) { | |
973 | fput(files[0]); | |
974 | fput(files[1]); | |
975 | put_unused_fd(fd[0]); | |
976 | put_unused_fd(fd[1]); | |
977 | error = -EFAULT; | |
978 | } else { | |
979 | fd_install(fd[0], files[0]); | |
980 | fd_install(fd[1], files[1]); | |
981 | } | |
982 | } | |
983 | return error; | |
984 | } | |
985 | ||
986 | SYSCALL_DEFINE2(pipe2, int __user *, fildes, int, flags) | |
987 | { | |
988 | return do_pipe2(fildes, flags); | |
989 | } | |
990 | ||
991 | SYSCALL_DEFINE1(pipe, int __user *, fildes) | |
992 | { | |
993 | return do_pipe2(fildes, 0); | |
994 | } | |
995 | ||
996 | static int wait_for_partner(struct pipe_inode_info *pipe, unsigned int *cnt) | |
997 | { | |
998 | int cur = *cnt; | |
999 | ||
1000 | while (cur == *cnt) { | |
1001 | pipe_wait(pipe); | |
1002 | if (signal_pending(current)) | |
1003 | break; | |
1004 | } | |
1005 | return cur == *cnt ? -ERESTARTSYS : 0; | |
1006 | } | |
1007 | ||
1008 | static void wake_up_partner(struct pipe_inode_info *pipe) | |
1009 | { | |
1010 | wake_up_interruptible(&pipe->wait); | |
1011 | } | |
1012 | ||
1013 | static int fifo_open(struct inode *inode, struct file *filp) | |
1014 | { | |
1015 | struct pipe_inode_info *pipe; | |
1016 | bool is_pipe = inode->i_sb->s_magic == PIPEFS_MAGIC; | |
1017 | int ret; | |
1018 | ||
1019 | filp->f_version = 0; | |
1020 | ||
1021 | spin_lock(&inode->i_lock); | |
1022 | if (inode->i_pipe) { | |
1023 | pipe = inode->i_pipe; | |
1024 | pipe->files++; | |
1025 | spin_unlock(&inode->i_lock); | |
1026 | } else { | |
1027 | spin_unlock(&inode->i_lock); | |
1028 | pipe = alloc_pipe_info(); | |
1029 | if (!pipe) | |
1030 | return -ENOMEM; | |
1031 | pipe->files = 1; | |
1032 | spin_lock(&inode->i_lock); | |
1033 | if (unlikely(inode->i_pipe)) { | |
1034 | inode->i_pipe->files++; | |
1035 | spin_unlock(&inode->i_lock); | |
1036 | free_pipe_info(pipe); | |
1037 | pipe = inode->i_pipe; | |
1038 | } else { | |
1039 | inode->i_pipe = pipe; | |
1040 | spin_unlock(&inode->i_lock); | |
1041 | } | |
1042 | } | |
1043 | filp->private_data = pipe; | |
1044 | /* OK, we have a pipe and it's pinned down */ | |
1045 | ||
1046 | __pipe_lock(pipe); | |
1047 | ||
1048 | /* We can only do regular read/write on fifos */ | |
1049 | stream_open(inode, filp); | |
1050 | ||
1051 | switch (filp->f_mode & (FMODE_READ | FMODE_WRITE)) { | |
1052 | case FMODE_READ: | |
1053 | /* | |
1054 | * O_RDONLY | |
1055 | * POSIX.1 says that O_NONBLOCK means return with the FIFO | |
1056 | * opened, even when there is no process writing the FIFO. | |
1057 | */ | |
1058 | pipe->r_counter++; | |
1059 | if (pipe->readers++ == 0) | |
1060 | wake_up_partner(pipe); | |
1061 | ||
1062 | if (!is_pipe && !pipe->writers) { | |
1063 | if ((filp->f_flags & O_NONBLOCK)) { | |
1064 | /* suppress EPOLLHUP until we have | |
1065 | * seen a writer */ | |
1066 | filp->f_version = pipe->w_counter; | |
1067 | } else { | |
1068 | if (wait_for_partner(pipe, &pipe->w_counter)) | |
1069 | goto err_rd; | |
1070 | } | |
1071 | } | |
1072 | break; | |
1073 | ||
1074 | case FMODE_WRITE: | |
1075 | /* | |
1076 | * O_WRONLY | |
1077 | * POSIX.1 says that O_NONBLOCK means return -1 with | |
1078 | * errno=ENXIO when there is no process reading the FIFO. | |
1079 | */ | |
1080 | ret = -ENXIO; | |
1081 | if (!is_pipe && (filp->f_flags & O_NONBLOCK) && !pipe->readers) | |
1082 | goto err; | |
1083 | ||
1084 | pipe->w_counter++; | |
1085 | if (!pipe->writers++) | |
1086 | wake_up_partner(pipe); | |
1087 | ||
1088 | if (!is_pipe && !pipe->readers) { | |
1089 | if (wait_for_partner(pipe, &pipe->r_counter)) | |
1090 | goto err_wr; | |
1091 | } | |
1092 | break; | |
1093 | ||
1094 | case FMODE_READ | FMODE_WRITE: | |
1095 | /* | |
1096 | * O_RDWR | |
1097 | * POSIX.1 leaves this case "undefined" when O_NONBLOCK is set. | |
1098 | * This implementation will NEVER block on a O_RDWR open, since | |
1099 | * the process can at least talk to itself. | |
1100 | */ | |
1101 | ||
1102 | pipe->readers++; | |
1103 | pipe->writers++; | |
1104 | pipe->r_counter++; | |
1105 | pipe->w_counter++; | |
1106 | if (pipe->readers == 1 || pipe->writers == 1) | |
1107 | wake_up_partner(pipe); | |
1108 | break; | |
1109 | ||
1110 | default: | |
1111 | ret = -EINVAL; | |
1112 | goto err; | |
1113 | } | |
1114 | ||
1115 | /* Ok! */ | |
1116 | __pipe_unlock(pipe); | |
1117 | return 0; | |
1118 | ||
1119 | err_rd: | |
1120 | if (!--pipe->readers) | |
1121 | wake_up_interruptible(&pipe->wait); | |
1122 | ret = -ERESTARTSYS; | |
1123 | goto err; | |
1124 | ||
1125 | err_wr: | |
1126 | if (!--pipe->writers) | |
1127 | wake_up_interruptible(&pipe->wait); | |
1128 | ret = -ERESTARTSYS; | |
1129 | goto err; | |
1130 | ||
1131 | err: | |
1132 | __pipe_unlock(pipe); | |
1133 | ||
1134 | put_pipe_info(inode, pipe); | |
1135 | return ret; | |
1136 | } | |
1137 | ||
1138 | const struct file_operations pipefifo_fops = { | |
1139 | .open = fifo_open, | |
1140 | .llseek = no_llseek, | |
1141 | .read_iter = pipe_read, | |
1142 | .write_iter = pipe_write, | |
1143 | .poll = pipe_poll, | |
1144 | .unlocked_ioctl = pipe_ioctl, | |
1145 | .release = pipe_release, | |
1146 | .fasync = pipe_fasync, | |
1147 | }; | |
1148 | ||
1149 | /* | |
1150 | * Currently we rely on the pipe array holding a power-of-2 number | |
1151 | * of pages. Returns 0 on error. | |
1152 | */ | |
1153 | unsigned int round_pipe_size(unsigned long size) | |
1154 | { | |
1155 | if (size > (1U << 31)) | |
1156 | return 0; | |
1157 | ||
1158 | /* Minimum pipe size, as required by POSIX */ | |
1159 | if (size < PAGE_SIZE) | |
1160 | return PAGE_SIZE; | |
1161 | ||
1162 | return roundup_pow_of_two(size); | |
1163 | } | |
1164 | ||
1165 | /* | |
1166 | * Allocate a new array of pipe buffers and copy the info over. Returns the | |
1167 | * pipe size if successful, or return -ERROR on error. | |
1168 | */ | |
1169 | static long pipe_set_size(struct pipe_inode_info *pipe, unsigned long arg) | |
1170 | { | |
1171 | struct pipe_buffer *bufs; | |
1172 | unsigned int size, nr_slots, head, tail, mask, n; | |
1173 | unsigned long user_bufs; | |
1174 | long ret = 0; | |
1175 | ||
1176 | size = round_pipe_size(arg); | |
1177 | nr_slots = size >> PAGE_SHIFT; | |
1178 | ||
1179 | if (!nr_slots) | |
1180 | return -EINVAL; | |
1181 | ||
1182 | /* | |
1183 | * If trying to increase the pipe capacity, check that an | |
1184 | * unprivileged user is not trying to exceed various limits | |
1185 | * (soft limit check here, hard limit check just below). | |
1186 | * Decreasing the pipe capacity is always permitted, even | |
1187 | * if the user is currently over a limit. | |
1188 | */ | |
1189 | if (nr_slots > pipe->ring_size && | |
1190 | size > pipe_max_size && !capable(CAP_SYS_RESOURCE)) | |
1191 | return -EPERM; | |
1192 | ||
1193 | user_bufs = account_pipe_buffers(pipe->user, pipe->ring_size, nr_slots); | |
1194 | ||
1195 | if (nr_slots > pipe->ring_size && | |
1196 | (too_many_pipe_buffers_hard(user_bufs) || | |
1197 | too_many_pipe_buffers_soft(user_bufs)) && | |
1198 | is_unprivileged_user()) { | |
1199 | ret = -EPERM; | |
1200 | goto out_revert_acct; | |
1201 | } | |
1202 | ||
1203 | /* | |
1204 | * We can shrink the pipe, if arg is greater than the ring occupancy. | |
1205 | * Since we don't expect a lot of shrink+grow operations, just free and | |
1206 | * allocate again like we would do for growing. If the pipe currently | |
1207 | * contains more buffers than arg, then return busy. | |
1208 | */ | |
1209 | mask = pipe->ring_size - 1; | |
1210 | head = pipe->head; | |
1211 | tail = pipe->tail; | |
1212 | n = pipe_occupancy(pipe->head, pipe->tail); | |
1213 | if (nr_slots < n) { | |
1214 | ret = -EBUSY; | |
1215 | goto out_revert_acct; | |
1216 | } | |
1217 | ||
1218 | bufs = kcalloc(nr_slots, sizeof(*bufs), | |
1219 | GFP_KERNEL_ACCOUNT | __GFP_NOWARN); | |
1220 | if (unlikely(!bufs)) { | |
1221 | ret = -ENOMEM; | |
1222 | goto out_revert_acct; | |
1223 | } | |
1224 | ||
1225 | /* | |
1226 | * The pipe array wraps around, so just start the new one at zero | |
1227 | * and adjust the indices. | |
1228 | */ | |
1229 | if (n > 0) { | |
1230 | unsigned int h = head & mask; | |
1231 | unsigned int t = tail & mask; | |
1232 | if (h > t) { | |
1233 | memcpy(bufs, pipe->bufs + t, | |
1234 | n * sizeof(struct pipe_buffer)); | |
1235 | } else { | |
1236 | unsigned int tsize = pipe->ring_size - t; | |
1237 | if (h > 0) | |
1238 | memcpy(bufs + tsize, pipe->bufs, | |
1239 | h * sizeof(struct pipe_buffer)); | |
1240 | memcpy(bufs, pipe->bufs + t, | |
1241 | tsize * sizeof(struct pipe_buffer)); | |
1242 | } | |
1243 | } | |
1244 | ||
1245 | head = n; | |
1246 | tail = 0; | |
1247 | ||
1248 | kfree(pipe->bufs); | |
1249 | pipe->bufs = bufs; | |
1250 | pipe->ring_size = nr_slots; | |
1251 | pipe->max_usage = nr_slots; | |
1252 | pipe->tail = tail; | |
1253 | pipe->head = head; | |
1254 | wake_up_interruptible_all(&pipe->wait); | |
1255 | return pipe->max_usage * PAGE_SIZE; | |
1256 | ||
1257 | out_revert_acct: | |
1258 | (void) account_pipe_buffers(pipe->user, nr_slots, pipe->ring_size); | |
1259 | return ret; | |
1260 | } | |
1261 | ||
1262 | /* | |
1263 | * After the inode slimming patch, i_pipe/i_bdev/i_cdev share the same | |
1264 | * location, so checking ->i_pipe is not enough to verify that this is a | |
1265 | * pipe. | |
1266 | */ | |
1267 | struct pipe_inode_info *get_pipe_info(struct file *file) | |
1268 | { | |
1269 | return file->f_op == &pipefifo_fops ? file->private_data : NULL; | |
1270 | } | |
1271 | ||
1272 | long pipe_fcntl(struct file *file, unsigned int cmd, unsigned long arg) | |
1273 | { | |
1274 | struct pipe_inode_info *pipe; | |
1275 | long ret; | |
1276 | ||
1277 | pipe = get_pipe_info(file); | |
1278 | if (!pipe) | |
1279 | return -EBADF; | |
1280 | ||
1281 | __pipe_lock(pipe); | |
1282 | ||
1283 | switch (cmd) { | |
1284 | case F_SETPIPE_SZ: | |
1285 | ret = pipe_set_size(pipe, arg); | |
1286 | break; | |
1287 | case F_GETPIPE_SZ: | |
1288 | ret = pipe->max_usage * PAGE_SIZE; | |
1289 | break; | |
1290 | default: | |
1291 | ret = -EINVAL; | |
1292 | break; | |
1293 | } | |
1294 | ||
1295 | __pipe_unlock(pipe); | |
1296 | return ret; | |
1297 | } | |
1298 | ||
1299 | static const struct super_operations pipefs_ops = { | |
1300 | .destroy_inode = free_inode_nonrcu, | |
1301 | .statfs = simple_statfs, | |
1302 | }; | |
1303 | ||
1304 | /* | |
1305 | * pipefs should _never_ be mounted by userland - too much of security hassle, | |
1306 | * no real gain from having the whole whorehouse mounted. So we don't need | |
1307 | * any operations on the root directory. However, we need a non-trivial | |
1308 | * d_name - pipe: will go nicely and kill the special-casing in procfs. | |
1309 | */ | |
1310 | ||
1311 | static int pipefs_init_fs_context(struct fs_context *fc) | |
1312 | { | |
1313 | struct pseudo_fs_context *ctx = init_pseudo(fc, PIPEFS_MAGIC); | |
1314 | if (!ctx) | |
1315 | return -ENOMEM; | |
1316 | ctx->ops = &pipefs_ops; | |
1317 | ctx->dops = &pipefs_dentry_operations; | |
1318 | return 0; | |
1319 | } | |
1320 | ||
1321 | static struct file_system_type pipe_fs_type = { | |
1322 | .name = "pipefs", | |
1323 | .init_fs_context = pipefs_init_fs_context, | |
1324 | .kill_sb = kill_anon_super, | |
1325 | }; | |
1326 | ||
1327 | static int __init init_pipe_fs(void) | |
1328 | { | |
1329 | int err = register_filesystem(&pipe_fs_type); | |
1330 | ||
1331 | if (!err) { | |
1332 | pipe_mnt = kern_mount(&pipe_fs_type); | |
1333 | if (IS_ERR(pipe_mnt)) { | |
1334 | err = PTR_ERR(pipe_mnt); | |
1335 | unregister_filesystem(&pipe_fs_type); | |
1336 | } | |
1337 | } | |
1338 | return err; | |
1339 | } | |
1340 | ||
1341 | fs_initcall(init_pipe_fs); |