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1 | /* |
2 | * linux/fs/pipe.c |
3 | * |
4 | * Copyright (C) 1991, 1992, 1999 Linus Torvalds |
5 | */ |
6 | |
7 | #include <linux/mm.h> |
8 | #include <linux/file.h> |
9 | #include <linux/poll.h> |
10 | #include <linux/slab.h> |
11 | #include <linux/module.h> |
12 | #include <linux/init.h> |
13 | #include <linux/fs.h> |
14 | #include <linux/log2.h> |
15 | #include <linux/mount.h> |
16 | #include <linux/pipe_fs_i.h> |
17 | #include <linux/uio.h> |
18 | #include <linux/highmem.h> |
19 | #include <linux/pagemap.h> |
20 | #include <linux/audit.h> |
21 | #include <linux/syscalls.h> |
22 | #include <linux/fcntl.h> |
23 | |
24 | #include <asm/uaccess.h> |
25 | #include <asm/ioctls.h> |
26 | |
27 | /* |
28 | * The max size that a non-root user is allowed to grow the pipe. Can |
29 | * be set by root in /proc/sys/fs/pipe-max-size |
30 | */ |
31 | unsigned int pipe_max_size = 1048576; |
32 | |
33 | /* |
34 | * Minimum pipe size, as required by POSIX |
35 | */ |
36 | unsigned int pipe_min_size = PAGE_SIZE; |
37 | |
38 | /* |
39 | * We use a start+len construction, which provides full use of the |
40 | * allocated memory. |
41 | * -- Florian Coosmann (FGC) |
42 | * |
43 | * Reads with count = 0 should always return 0. |
44 | * -- Julian Bradfield 1999-06-07. |
45 | * |
46 | * FIFOs and Pipes now generate SIGIO for both readers and writers. |
47 | * -- Jeremy Elson <jelson@circlemud.org> 2001-08-16 |
48 | * |
49 | * pipe_read & write cleanup |
50 | * -- Manfred Spraul <manfred@colorfullife.com> 2002-05-09 |
51 | */ |
52 | |
53 | static void pipe_lock_nested(struct pipe_inode_info *pipe, int subclass) |
54 | { |
55 | if (pipe->inode) |
56 | mutex_lock_nested(&pipe->inode->i_mutex, subclass); |
57 | } |
58 | |
59 | void pipe_lock(struct pipe_inode_info *pipe) |
60 | { |
61 | /* |
62 | * pipe_lock() nests non-pipe inode locks (for writing to a file) |
63 | */ |
64 | pipe_lock_nested(pipe, I_MUTEX_PARENT); |
65 | } |
66 | EXPORT_SYMBOL(pipe_lock); |
67 | |
68 | void pipe_unlock(struct pipe_inode_info *pipe) |
69 | { |
70 | if (pipe->inode) |
71 | mutex_unlock(&pipe->inode->i_mutex); |
72 | } |
73 | EXPORT_SYMBOL(pipe_unlock); |
74 | |
75 | void pipe_double_lock(struct pipe_inode_info *pipe1, |
76 | struct pipe_inode_info *pipe2) |
77 | { |
78 | BUG_ON(pipe1 == pipe2); |
79 | |
80 | if (pipe1 < pipe2) { |
81 | pipe_lock_nested(pipe1, I_MUTEX_PARENT); |
82 | pipe_lock_nested(pipe2, I_MUTEX_CHILD); |
83 | } else { |
84 | pipe_lock_nested(pipe2, I_MUTEX_PARENT); |
85 | pipe_lock_nested(pipe1, I_MUTEX_CHILD); |
86 | } |
87 | } |
88 | |
89 | /* Drop the inode semaphore and wait for a pipe event, atomically */ |
90 | void pipe_wait(struct pipe_inode_info *pipe) |
91 | { |
92 | DEFINE_WAIT(wait); |
93 | |
94 | /* |
95 | * Pipes are system-local resources, so sleeping on them |
96 | * is considered a noninteractive wait: |
97 | */ |
98 | prepare_to_wait(&pipe->wait, &wait, TASK_INTERRUPTIBLE); |
99 | pipe_unlock(pipe); |
100 | schedule(); |
101 | finish_wait(&pipe->wait, &wait); |
102 | pipe_lock(pipe); |
103 | } |
104 | |
105 | static int |
106 | pipe_iov_copy_from_user(void *to, struct iovec *iov, unsigned long len, |
107 | int atomic) |
108 | { |
109 | unsigned long copy; |
110 | |
111 | while (len > 0) { |
112 | while (!iov->iov_len) |
113 | iov++; |
114 | copy = min_t(unsigned long, len, iov->iov_len); |
115 | |
116 | if (atomic) { |
117 | if (__copy_from_user_inatomic(to, iov->iov_base, copy)) |
118 | return -EFAULT; |
119 | } else { |
120 | if (copy_from_user(to, iov->iov_base, copy)) |
121 | return -EFAULT; |
122 | } |
123 | to += copy; |
124 | len -= copy; |
125 | iov->iov_base += copy; |
126 | iov->iov_len -= copy; |
127 | } |
128 | return 0; |
129 | } |
130 | |
131 | static int |
132 | pipe_iov_copy_to_user(struct iovec *iov, const void *from, unsigned long len, |
133 | int atomic) |
134 | { |
135 | unsigned long copy; |
136 | |
137 | while (len > 0) { |
138 | while (!iov->iov_len) |
139 | iov++; |
140 | copy = min_t(unsigned long, len, iov->iov_len); |
141 | |
142 | if (atomic) { |
143 | if (__copy_to_user_inatomic(iov->iov_base, from, copy)) |
144 | return -EFAULT; |
145 | } else { |
146 | if (copy_to_user(iov->iov_base, from, copy)) |
147 | return -EFAULT; |
148 | } |
149 | from += copy; |
150 | len -= copy; |
151 | iov->iov_base += copy; |
152 | iov->iov_len -= copy; |
153 | } |
154 | return 0; |
155 | } |
156 | |
157 | /* |
158 | * Attempt to pre-fault in the user memory, so we can use atomic copies. |
159 | * Returns the number of bytes not faulted in. |
160 | */ |
161 | static int iov_fault_in_pages_write(struct iovec *iov, unsigned long len) |
162 | { |
163 | while (!iov->iov_len) |
164 | iov++; |
165 | |
166 | while (len > 0) { |
167 | unsigned long this_len; |
168 | |
169 | this_len = min_t(unsigned long, len, iov->iov_len); |
170 | if (fault_in_pages_writeable(iov->iov_base, this_len)) |
171 | break; |
172 | |
173 | len -= this_len; |
174 | iov++; |
175 | } |
176 | |
177 | return len; |
178 | } |
179 | |
180 | /* |
181 | * Pre-fault in the user memory, so we can use atomic copies. |
182 | */ |
183 | static void iov_fault_in_pages_read(struct iovec *iov, unsigned long len) |
184 | { |
185 | while (!iov->iov_len) |
186 | iov++; |
187 | |
188 | while (len > 0) { |
189 | unsigned long this_len; |
190 | |
191 | this_len = min_t(unsigned long, len, iov->iov_len); |
192 | fault_in_pages_readable(iov->iov_base, this_len); |
193 | len -= this_len; |
194 | iov++; |
195 | } |
196 | } |
197 | |
198 | static void anon_pipe_buf_release(struct pipe_inode_info *pipe, |
199 | struct pipe_buffer *buf) |
200 | { |
201 | struct page *page = buf->page; |
202 | |
203 | /* |
204 | * If nobody else uses this page, and we don't already have a |
205 | * temporary page, let's keep track of it as a one-deep |
206 | * allocation cache. (Otherwise just release our reference to it) |
207 | */ |
208 | if (page_count(page) == 1 && !pipe->tmp_page) |
209 | pipe->tmp_page = page; |
210 | else |
211 | page_cache_release(page); |
212 | } |
213 | |
214 | /** |
215 | * generic_pipe_buf_map - virtually map a pipe buffer |
216 | * @pipe: the pipe that the buffer belongs to |
217 | * @buf: the buffer that should be mapped |
218 | * @atomic: whether to use an atomic map |
219 | * |
220 | * Description: |
221 | * This function returns a kernel virtual address mapping for the |
222 | * pipe_buffer passed in @buf. If @atomic is set, an atomic map is provided |
223 | * and the caller has to be careful not to fault before calling |
224 | * the unmap function. |
225 | * |
226 | * Note that this function occupies KM_USER0 if @atomic != 0. |
227 | */ |
228 | void *generic_pipe_buf_map(struct pipe_inode_info *pipe, |
229 | struct pipe_buffer *buf, int atomic) |
230 | { |
231 | if (atomic) { |
232 | buf->flags |= PIPE_BUF_FLAG_ATOMIC; |
233 | return kmap_atomic(buf->page, KM_USER0); |
234 | } |
235 | |
236 | return kmap(buf->page); |
237 | } |
238 | EXPORT_SYMBOL(generic_pipe_buf_map); |
239 | |
240 | /** |
241 | * generic_pipe_buf_unmap - unmap a previously mapped pipe buffer |
242 | * @pipe: the pipe that the buffer belongs to |
243 | * @buf: the buffer that should be unmapped |
244 | * @map_data: the data that the mapping function returned |
245 | * |
246 | * Description: |
247 | * This function undoes the mapping that ->map() provided. |
248 | */ |
249 | void generic_pipe_buf_unmap(struct pipe_inode_info *pipe, |
250 | struct pipe_buffer *buf, void *map_data) |
251 | { |
252 | if (buf->flags & PIPE_BUF_FLAG_ATOMIC) { |
253 | buf->flags &= ~PIPE_BUF_FLAG_ATOMIC; |
254 | kunmap_atomic(map_data, KM_USER0); |
255 | } else |
256 | kunmap(buf->page); |
257 | } |
258 | EXPORT_SYMBOL(generic_pipe_buf_unmap); |
259 | |
260 | /** |
261 | * generic_pipe_buf_steal - attempt to take ownership of a &pipe_buffer |
262 | * @pipe: the pipe that the buffer belongs to |
263 | * @buf: the buffer to attempt to steal |
264 | * |
265 | * Description: |
266 | * This function attempts to steal the &struct page attached to |
267 | * @buf. If successful, this function returns 0 and returns with |
268 | * the page locked. The caller may then reuse the page for whatever |
269 | * he wishes; the typical use is insertion into a different file |
270 | * page cache. |
271 | */ |
272 | int generic_pipe_buf_steal(struct pipe_inode_info *pipe, |
273 | struct pipe_buffer *buf) |
274 | { |
275 | struct page *page = buf->page; |
276 | |
277 | /* |
278 | * A reference of one is golden, that means that the owner of this |
279 | * page is the only one holding a reference to it. lock the page |
280 | * and return OK. |
281 | */ |
282 | if (page_count(page) == 1) { |
283 | lock_page(page); |
284 | return 0; |
285 | } |
286 | |
287 | return 1; |
288 | } |
289 | EXPORT_SYMBOL(generic_pipe_buf_steal); |
290 | |
291 | /** |
292 | * generic_pipe_buf_get - get a reference to a &struct pipe_buffer |
293 | * @pipe: the pipe that the buffer belongs to |
294 | * @buf: the buffer to get a reference to |
295 | * |
296 | * Description: |
297 | * This function grabs an extra reference to @buf. It's used in |
298 | * in the tee() system call, when we duplicate the buffers in one |
299 | * pipe into another. |
300 | */ |
301 | void generic_pipe_buf_get(struct pipe_inode_info *pipe, struct pipe_buffer *buf) |
302 | { |
303 | page_cache_get(buf->page); |
304 | } |
305 | EXPORT_SYMBOL(generic_pipe_buf_get); |
306 | |
307 | /** |
308 | * generic_pipe_buf_confirm - verify contents of the pipe buffer |
309 | * @info: the pipe that the buffer belongs to |
310 | * @buf: the buffer to confirm |
311 | * |
312 | * Description: |
313 | * This function does nothing, because the generic pipe code uses |
314 | * pages that are always good when inserted into the pipe. |
315 | */ |
316 | int generic_pipe_buf_confirm(struct pipe_inode_info *info, |
317 | struct pipe_buffer *buf) |
318 | { |
319 | return 0; |
320 | } |
321 | EXPORT_SYMBOL(generic_pipe_buf_confirm); |
322 | |
323 | /** |
324 | * generic_pipe_buf_release - put a reference to a &struct pipe_buffer |
325 | * @pipe: the pipe that the buffer belongs to |
326 | * @buf: the buffer to put a reference to |
327 | * |
328 | * Description: |
329 | * This function releases a reference to @buf. |
330 | */ |
331 | void generic_pipe_buf_release(struct pipe_inode_info *pipe, |
332 | struct pipe_buffer *buf) |
333 | { |
334 | page_cache_release(buf->page); |
335 | } |
336 | EXPORT_SYMBOL(generic_pipe_buf_release); |
337 | |
338 | static const struct pipe_buf_operations anon_pipe_buf_ops = { |
339 | .can_merge = 1, |
340 | .map = generic_pipe_buf_map, |
341 | .unmap = generic_pipe_buf_unmap, |
342 | .confirm = generic_pipe_buf_confirm, |
343 | .release = anon_pipe_buf_release, |
344 | .steal = generic_pipe_buf_steal, |
345 | .get = generic_pipe_buf_get, |
346 | }; |
347 | |
348 | static ssize_t |
349 | pipe_read(struct kiocb *iocb, const struct iovec *_iov, |
350 | unsigned long nr_segs, loff_t pos) |
351 | { |
352 | struct file *filp = iocb->ki_filp; |
353 | struct inode *inode = filp->f_path.dentry->d_inode; |
354 | struct pipe_inode_info *pipe; |
355 | int do_wakeup; |
356 | ssize_t ret; |
357 | struct iovec *iov = (struct iovec *)_iov; |
358 | size_t total_len; |
359 | |
360 | total_len = iov_length(iov, nr_segs); |
361 | /* Null read succeeds. */ |
362 | if (unlikely(total_len == 0)) |
363 | return 0; |
364 | |
365 | do_wakeup = 0; |
366 | ret = 0; |
367 | mutex_lock(&inode->i_mutex); |
368 | pipe = inode->i_pipe; |
369 | for (;;) { |
370 | int bufs = pipe->nrbufs; |
371 | if (bufs) { |
372 | int curbuf = pipe->curbuf; |
373 | struct pipe_buffer *buf = pipe->bufs + curbuf; |
374 | const struct pipe_buf_operations *ops = buf->ops; |
375 | void *addr; |
376 | size_t chars = buf->len; |
377 | int error, atomic; |
378 | |
379 | if (chars > total_len) |
380 | chars = total_len; |
381 | |
382 | error = ops->confirm(pipe, buf); |
383 | if (error) { |
384 | if (!ret) |
385 | error = ret; |
386 | break; |
387 | } |
388 | |
389 | atomic = !iov_fault_in_pages_write(iov, chars); |
390 | redo: |
391 | addr = ops->map(pipe, buf, atomic); |
392 | error = pipe_iov_copy_to_user(iov, addr + buf->offset, chars, atomic); |
393 | ops->unmap(pipe, buf, addr); |
394 | if (unlikely(error)) { |
395 | /* |
396 | * Just retry with the slow path if we failed. |
397 | */ |
398 | if (atomic) { |
399 | atomic = 0; |
400 | goto redo; |
401 | } |
402 | if (!ret) |
403 | ret = error; |
404 | break; |
405 | } |
406 | ret += chars; |
407 | buf->offset += chars; |
408 | buf->len -= chars; |
409 | if (!buf->len) { |
410 | buf->ops = NULL; |
411 | ops->release(pipe, buf); |
412 | curbuf = (curbuf + 1) & (pipe->buffers - 1); |
413 | pipe->curbuf = curbuf; |
414 | pipe->nrbufs = --bufs; |
415 | do_wakeup = 1; |
416 | } |
417 | total_len -= chars; |
418 | if (!total_len) |
419 | break; /* common path: read succeeded */ |
420 | } |
421 | if (bufs) /* More to do? */ |
422 | continue; |
423 | if (!pipe->writers) |
424 | break; |
425 | if (!pipe->waiting_writers) { |
426 | /* syscall merging: Usually we must not sleep |
427 | * if O_NONBLOCK is set, or if we got some data. |
428 | * But if a writer sleeps in kernel space, then |
429 | * we can wait for that data without violating POSIX. |
430 | */ |
431 | if (ret) |
432 | break; |
433 | if (filp->f_flags & O_NONBLOCK) { |
434 | ret = -EAGAIN; |
435 | break; |
436 | } |
437 | } |
438 | if (signal_pending(current)) { |
439 | if (!ret) |
440 | ret = -ERESTARTSYS; |
441 | break; |
442 | } |
443 | if (do_wakeup) { |
444 | wake_up_interruptible_sync(&pipe->wait); |
445 | kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT); |
446 | } |
447 | pipe_wait(pipe); |
448 | } |
449 | mutex_unlock(&inode->i_mutex); |
450 | |
451 | /* Signal writers asynchronously that there is more room. */ |
452 | if (do_wakeup) { |
453 | wake_up_interruptible_sync(&pipe->wait); |
454 | kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT); |
455 | } |
456 | if (ret > 0) |
457 | file_accessed(filp); |
458 | return ret; |
459 | } |
460 | |
461 | static ssize_t |
462 | pipe_write(struct kiocb *iocb, const struct iovec *_iov, |
463 | unsigned long nr_segs, loff_t ppos) |
464 | { |
465 | struct file *filp = iocb->ki_filp; |
466 | struct inode *inode = filp->f_path.dentry->d_inode; |
467 | struct pipe_inode_info *pipe; |
468 | ssize_t ret; |
469 | int do_wakeup; |
470 | struct iovec *iov = (struct iovec *)_iov; |
471 | size_t total_len; |
472 | ssize_t chars; |
473 | |
474 | total_len = iov_length(iov, nr_segs); |
475 | /* Null write succeeds. */ |
476 | if (unlikely(total_len == 0)) |
477 | return 0; |
478 | |
479 | do_wakeup = 0; |
480 | ret = 0; |
481 | mutex_lock(&inode->i_mutex); |
482 | pipe = inode->i_pipe; |
483 | |
484 | if (!pipe->readers) { |
485 | send_sig(SIGPIPE, current, 0); |
486 | ret = -EPIPE; |
487 | goto out; |
488 | } |
489 | |
490 | /* We try to merge small writes */ |
491 | chars = total_len & (PAGE_SIZE-1); /* size of the last buffer */ |
492 | if (pipe->nrbufs && chars != 0) { |
493 | int lastbuf = (pipe->curbuf + pipe->nrbufs - 1) & |
494 | (pipe->buffers - 1); |
495 | struct pipe_buffer *buf = pipe->bufs + lastbuf; |
496 | const struct pipe_buf_operations *ops = buf->ops; |
497 | int offset = buf->offset + buf->len; |
498 | |
499 | if (ops->can_merge && offset + chars <= PAGE_SIZE) { |
500 | int error, atomic = 1; |
501 | void *addr; |
502 | |
503 | error = ops->confirm(pipe, buf); |
504 | if (error) |
505 | goto out; |
506 | |
507 | iov_fault_in_pages_read(iov, chars); |
508 | redo1: |
509 | addr = ops->map(pipe, buf, atomic); |
510 | error = pipe_iov_copy_from_user(offset + addr, iov, |
511 | chars, atomic); |
512 | ops->unmap(pipe, buf, addr); |
513 | ret = error; |
514 | do_wakeup = 1; |
515 | if (error) { |
516 | if (atomic) { |
517 | atomic = 0; |
518 | goto redo1; |
519 | } |
520 | goto out; |
521 | } |
522 | buf->len += chars; |
523 | total_len -= chars; |
524 | ret = chars; |
525 | if (!total_len) |
526 | goto out; |
527 | } |
528 | } |
529 | |
530 | for (;;) { |
531 | int bufs; |
532 | |
533 | if (!pipe->readers) { |
534 | send_sig(SIGPIPE, current, 0); |
535 | if (!ret) |
536 | ret = -EPIPE; |
537 | break; |
538 | } |
539 | bufs = pipe->nrbufs; |
540 | if (bufs < pipe->buffers) { |
541 | int newbuf = (pipe->curbuf + bufs) & (pipe->buffers-1); |
542 | struct pipe_buffer *buf = pipe->bufs + newbuf; |
543 | struct page *page = pipe->tmp_page; |
544 | char *src; |
545 | int error, atomic = 1; |
546 | |
547 | if (!page) { |
548 | page = alloc_page(GFP_HIGHUSER); |
549 | if (unlikely(!page)) { |
550 | ret = ret ? : -ENOMEM; |
551 | break; |
552 | } |
553 | pipe->tmp_page = page; |
554 | } |
555 | /* Always wake up, even if the copy fails. Otherwise |
556 | * we lock up (O_NONBLOCK-)readers that sleep due to |
557 | * syscall merging. |
558 | * FIXME! Is this really true? |
559 | */ |
560 | do_wakeup = 1; |
561 | chars = PAGE_SIZE; |
562 | if (chars > total_len) |
563 | chars = total_len; |
564 | |
565 | iov_fault_in_pages_read(iov, chars); |
566 | redo2: |
567 | if (atomic) |
568 | src = kmap_atomic(page, KM_USER0); |
569 | else |
570 | src = kmap(page); |
571 | |
572 | error = pipe_iov_copy_from_user(src, iov, chars, |
573 | atomic); |
574 | if (atomic) |
575 | kunmap_atomic(src, KM_USER0); |
576 | else |
577 | kunmap(page); |
578 | |
579 | if (unlikely(error)) { |
580 | if (atomic) { |
581 | atomic = 0; |
582 | goto redo2; |
583 | } |
584 | if (!ret) |
585 | ret = error; |
586 | break; |
587 | } |
588 | ret += chars; |
589 | |
590 | /* Insert it into the buffer array */ |
591 | buf->page = page; |
592 | buf->ops = &anon_pipe_buf_ops; |
593 | buf->offset = 0; |
594 | buf->len = chars; |
595 | pipe->nrbufs = ++bufs; |
596 | pipe->tmp_page = NULL; |
597 | |
598 | total_len -= chars; |
599 | if (!total_len) |
600 | break; |
601 | } |
602 | if (bufs < pipe->buffers) |
603 | continue; |
604 | if (filp->f_flags & O_NONBLOCK) { |
605 | if (!ret) |
606 | ret = -EAGAIN; |
607 | break; |
608 | } |
609 | if (signal_pending(current)) { |
610 | if (!ret) |
611 | ret = -ERESTARTSYS; |
612 | break; |
613 | } |
614 | if (do_wakeup) { |
615 | wake_up_interruptible_sync(&pipe->wait); |
616 | kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN); |
617 | do_wakeup = 0; |
618 | } |
619 | pipe->waiting_writers++; |
620 | pipe_wait(pipe); |
621 | pipe->waiting_writers--; |
622 | } |
623 | out: |
624 | mutex_unlock(&inode->i_mutex); |
625 | if (do_wakeup) { |
626 | wake_up_interruptible_sync(&pipe->wait); |
627 | kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN); |
628 | } |
629 | if (ret > 0) |
630 | file_update_time(filp); |
631 | return ret; |
632 | } |
633 | |
634 | static ssize_t |
635 | bad_pipe_r(struct file *filp, char __user *buf, size_t count, loff_t *ppos) |
636 | { |
637 | return -EBADF; |
638 | } |
639 | |
640 | static ssize_t |
641 | bad_pipe_w(struct file *filp, const char __user *buf, size_t count, |
642 | loff_t *ppos) |
643 | { |
644 | return -EBADF; |
645 | } |
646 | |
647 | static long pipe_ioctl(struct file *filp, unsigned int cmd, unsigned long arg) |
648 | { |
649 | struct inode *inode = filp->f_path.dentry->d_inode; |
650 | struct pipe_inode_info *pipe; |
651 | int count, buf, nrbufs; |
652 | |
653 | switch (cmd) { |
654 | case FIONREAD: |
655 | mutex_lock(&inode->i_mutex); |
656 | pipe = inode->i_pipe; |
657 | count = 0; |
658 | buf = pipe->curbuf; |
659 | nrbufs = pipe->nrbufs; |
660 | while (--nrbufs >= 0) { |
661 | count += pipe->bufs[buf].len; |
662 | buf = (buf+1) & (pipe->buffers - 1); |
663 | } |
664 | mutex_unlock(&inode->i_mutex); |
665 | |
666 | return put_user(count, (int __user *)arg); |
667 | default: |
668 | return -EINVAL; |
669 | } |
670 | } |
671 | |
672 | /* No kernel lock held - fine */ |
673 | static unsigned int |
674 | pipe_poll(struct file *filp, poll_table *wait) |
675 | { |
676 | unsigned int mask; |
677 | struct inode *inode = filp->f_path.dentry->d_inode; |
678 | struct pipe_inode_info *pipe = inode->i_pipe; |
679 | int nrbufs; |
680 | |
681 | poll_wait(filp, &pipe->wait, wait); |
682 | |
683 | /* Reading only -- no need for acquiring the semaphore. */ |
684 | nrbufs = pipe->nrbufs; |
685 | mask = 0; |
686 | if (filp->f_mode & FMODE_READ) { |
687 | mask = (nrbufs > 0) ? POLLIN | POLLRDNORM : 0; |
688 | if (!pipe->writers && filp->f_version != pipe->w_counter) |
689 | mask |= POLLHUP; |
690 | } |
691 | |
692 | if (filp->f_mode & FMODE_WRITE) { |
693 | mask |= (nrbufs < pipe->buffers) ? POLLOUT | POLLWRNORM : 0; |
694 | /* |
695 | * Most Unices do not set POLLERR for FIFOs but on Linux they |
696 | * behave exactly like pipes for poll(). |
697 | */ |
698 | if (!pipe->readers) |
699 | mask |= POLLERR; |
700 | } |
701 | |
702 | return mask; |
703 | } |
704 | |
705 | static int |
706 | pipe_release(struct inode *inode, int decr, int decw) |
707 | { |
708 | struct pipe_inode_info *pipe; |
709 | |
710 | mutex_lock(&inode->i_mutex); |
711 | pipe = inode->i_pipe; |
712 | pipe->readers -= decr; |
713 | pipe->writers -= decw; |
714 | |
715 | if (!pipe->readers && !pipe->writers) { |
716 | free_pipe_info(inode); |
717 | } else { |
718 | wake_up_interruptible_sync(&pipe->wait); |
719 | kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN); |
720 | kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT); |
721 | } |
722 | mutex_unlock(&inode->i_mutex); |
723 | |
724 | return 0; |
725 | } |
726 | |
727 | static int |
728 | pipe_read_fasync(int fd, struct file *filp, int on) |
729 | { |
730 | struct inode *inode = filp->f_path.dentry->d_inode; |
731 | int retval; |
732 | |
733 | mutex_lock(&inode->i_mutex); |
734 | retval = fasync_helper(fd, filp, on, &inode->i_pipe->fasync_readers); |
735 | mutex_unlock(&inode->i_mutex); |
736 | |
737 | return retval; |
738 | } |
739 | |
740 | |
741 | static int |
742 | pipe_write_fasync(int fd, struct file *filp, int on) |
743 | { |
744 | struct inode *inode = filp->f_path.dentry->d_inode; |
745 | int retval; |
746 | |
747 | mutex_lock(&inode->i_mutex); |
748 | retval = fasync_helper(fd, filp, on, &inode->i_pipe->fasync_writers); |
749 | mutex_unlock(&inode->i_mutex); |
750 | |
751 | return retval; |
752 | } |
753 | |
754 | |
755 | static int |
756 | pipe_rdwr_fasync(int fd, struct file *filp, int on) |
757 | { |
758 | struct inode *inode = filp->f_path.dentry->d_inode; |
759 | struct pipe_inode_info *pipe = inode->i_pipe; |
760 | int retval; |
761 | |
762 | mutex_lock(&inode->i_mutex); |
763 | retval = fasync_helper(fd, filp, on, &pipe->fasync_readers); |
764 | if (retval >= 0) { |
765 | retval = fasync_helper(fd, filp, on, &pipe->fasync_writers); |
766 | if (retval < 0) /* this can happen only if on == T */ |
767 | fasync_helper(-1, filp, 0, &pipe->fasync_readers); |
768 | } |
769 | mutex_unlock(&inode->i_mutex); |
770 | return retval; |
771 | } |
772 | |
773 | |
774 | static int |
775 | pipe_read_release(struct inode *inode, struct file *filp) |
776 | { |
777 | return pipe_release(inode, 1, 0); |
778 | } |
779 | |
780 | static int |
781 | pipe_write_release(struct inode *inode, struct file *filp) |
782 | { |
783 | return pipe_release(inode, 0, 1); |
784 | } |
785 | |
786 | static int |
787 | pipe_rdwr_release(struct inode *inode, struct file *filp) |
788 | { |
789 | int decr, decw; |
790 | |
791 | decr = (filp->f_mode & FMODE_READ) != 0; |
792 | decw = (filp->f_mode & FMODE_WRITE) != 0; |
793 | return pipe_release(inode, decr, decw); |
794 | } |
795 | |
796 | static int |
797 | pipe_read_open(struct inode *inode, struct file *filp) |
798 | { |
799 | int ret = -ENOENT; |
800 | |
801 | mutex_lock(&inode->i_mutex); |
802 | |
803 | if (inode->i_pipe) { |
804 | ret = 0; |
805 | inode->i_pipe->readers++; |
806 | } |
807 | |
808 | mutex_unlock(&inode->i_mutex); |
809 | |
810 | return ret; |
811 | } |
812 | |
813 | static int |
814 | pipe_write_open(struct inode *inode, struct file *filp) |
815 | { |
816 | int ret = -ENOENT; |
817 | |
818 | mutex_lock(&inode->i_mutex); |
819 | |
820 | if (inode->i_pipe) { |
821 | ret = 0; |
822 | inode->i_pipe->writers++; |
823 | } |
824 | |
825 | mutex_unlock(&inode->i_mutex); |
826 | |
827 | return ret; |
828 | } |
829 | |
830 | static int |
831 | pipe_rdwr_open(struct inode *inode, struct file *filp) |
832 | { |
833 | int ret = -ENOENT; |
834 | |
835 | mutex_lock(&inode->i_mutex); |
836 | |
837 | if (inode->i_pipe) { |
838 | ret = 0; |
839 | if (filp->f_mode & FMODE_READ) |
840 | inode->i_pipe->readers++; |
841 | if (filp->f_mode & FMODE_WRITE) |
842 | inode->i_pipe->writers++; |
843 | } |
844 | |
845 | mutex_unlock(&inode->i_mutex); |
846 | |
847 | return ret; |
848 | } |
849 | |
850 | /* |
851 | * The file_operations structs are not static because they |
852 | * are also used in linux/fs/fifo.c to do operations on FIFOs. |
853 | * |
854 | * Pipes reuse fifos' file_operations structs. |
855 | */ |
856 | const struct file_operations read_pipefifo_fops = { |
857 | .llseek = no_llseek, |
858 | .read = do_sync_read, |
859 | .aio_read = pipe_read, |
860 | .write = bad_pipe_w, |
861 | .poll = pipe_poll, |
862 | .unlocked_ioctl = pipe_ioctl, |
863 | .open = pipe_read_open, |
864 | .release = pipe_read_release, |
865 | .fasync = pipe_read_fasync, |
866 | }; |
867 | |
868 | const struct file_operations write_pipefifo_fops = { |
869 | .llseek = no_llseek, |
870 | .read = bad_pipe_r, |
871 | .write = do_sync_write, |
872 | .aio_write = pipe_write, |
873 | .poll = pipe_poll, |
874 | .unlocked_ioctl = pipe_ioctl, |
875 | .open = pipe_write_open, |
876 | .release = pipe_write_release, |
877 | .fasync = pipe_write_fasync, |
878 | }; |
879 | |
880 | const struct file_operations rdwr_pipefifo_fops = { |
881 | .llseek = no_llseek, |
882 | .read = do_sync_read, |
883 | .aio_read = pipe_read, |
884 | .write = do_sync_write, |
885 | .aio_write = pipe_write, |
886 | .poll = pipe_poll, |
887 | .unlocked_ioctl = pipe_ioctl, |
888 | .open = pipe_rdwr_open, |
889 | .release = pipe_rdwr_release, |
890 | .fasync = pipe_rdwr_fasync, |
891 | }; |
892 | |
893 | struct pipe_inode_info * alloc_pipe_info(struct inode *inode) |
894 | { |
895 | struct pipe_inode_info *pipe; |
896 | |
897 | pipe = kzalloc(sizeof(struct pipe_inode_info), GFP_KERNEL); |
898 | if (pipe) { |
899 | pipe->bufs = kzalloc(sizeof(struct pipe_buffer) * PIPE_DEF_BUFFERS, GFP_KERNEL); |
900 | if (pipe->bufs) { |
901 | init_waitqueue_head(&pipe->wait); |
902 | pipe->r_counter = pipe->w_counter = 1; |
903 | pipe->inode = inode; |
904 | pipe->buffers = PIPE_DEF_BUFFERS; |
905 | return pipe; |
906 | } |
907 | kfree(pipe); |
908 | } |
909 | |
910 | return NULL; |
911 | } |
912 | |
913 | void __free_pipe_info(struct pipe_inode_info *pipe) |
914 | { |
915 | int i; |
916 | |
917 | for (i = 0; i < pipe->buffers; i++) { |
918 | struct pipe_buffer *buf = pipe->bufs + i; |
919 | if (buf->ops) |
920 | buf->ops->release(pipe, buf); |
921 | } |
922 | if (pipe->tmp_page) |
923 | __free_page(pipe->tmp_page); |
924 | kfree(pipe->bufs); |
925 | kfree(pipe); |
926 | } |
927 | |
928 | void free_pipe_info(struct inode *inode) |
929 | { |
930 | __free_pipe_info(inode->i_pipe); |
931 | inode->i_pipe = NULL; |
932 | } |
933 | |
934 | static struct vfsmount *pipe_mnt __read_mostly; |
935 | |
936 | /* |
937 | * pipefs_dname() is called from d_path(). |
938 | */ |
939 | static char *pipefs_dname(struct dentry *dentry, char *buffer, int buflen) |
940 | { |
941 | return dynamic_dname(dentry, buffer, buflen, "pipe:[%lu]", |
942 | dentry->d_inode->i_ino); |
943 | } |
944 | |
945 | static const struct dentry_operations pipefs_dentry_operations = { |
946 | .d_dname = pipefs_dname, |
947 | }; |
948 | |
949 | static struct inode * get_pipe_inode(void) |
950 | { |
951 | struct inode *inode = new_inode(pipe_mnt->mnt_sb); |
952 | struct pipe_inode_info *pipe; |
953 | |
954 | if (!inode) |
955 | goto fail_inode; |
956 | |
957 | pipe = alloc_pipe_info(inode); |
958 | if (!pipe) |
959 | goto fail_iput; |
960 | inode->i_pipe = pipe; |
961 | |
962 | pipe->readers = pipe->writers = 1; |
963 | inode->i_fop = &rdwr_pipefifo_fops; |
964 | |
965 | /* |
966 | * Mark the inode dirty from the very beginning, |
967 | * that way it will never be moved to the dirty |
968 | * list because "mark_inode_dirty()" will think |
969 | * that it already _is_ on the dirty list. |
970 | */ |
971 | inode->i_state = I_DIRTY; |
972 | inode->i_mode = S_IFIFO | S_IRUSR | S_IWUSR; |
973 | inode->i_uid = current_fsuid(); |
974 | inode->i_gid = current_fsgid(); |
975 | inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; |
976 | |
977 | return inode; |
978 | |
979 | fail_iput: |
980 | iput(inode); |
981 | |
982 | fail_inode: |
983 | return NULL; |
984 | } |
985 | |
986 | struct file *create_write_pipe(int flags) |
987 | { |
988 | int err; |
989 | struct inode *inode; |
990 | struct file *f; |
991 | struct path path; |
992 | struct qstr name = { .name = "" }; |
993 | |
994 | err = -ENFILE; |
995 | inode = get_pipe_inode(); |
996 | if (!inode) |
997 | goto err; |
998 | |
999 | err = -ENOMEM; |
1000 | path.dentry = d_alloc(pipe_mnt->mnt_sb->s_root, &name); |
1001 | if (!path.dentry) |
1002 | goto err_inode; |
1003 | path.mnt = mntget(pipe_mnt); |
1004 | |
1005 | path.dentry->d_op = &pipefs_dentry_operations; |
1006 | d_instantiate(path.dentry, inode); |
1007 | |
1008 | err = -ENFILE; |
1009 | f = alloc_file(&path, FMODE_WRITE, &write_pipefifo_fops); |
1010 | if (!f) |
1011 | goto err_dentry; |
1012 | f->f_mapping = inode->i_mapping; |
1013 | |
1014 | f->f_flags = O_WRONLY | (flags & O_NONBLOCK); |
1015 | f->f_version = 0; |
1016 | |
1017 | return f; |
1018 | |
1019 | err_dentry: |
1020 | free_pipe_info(inode); |
1021 | path_put(&path); |
1022 | return ERR_PTR(err); |
1023 | |
1024 | err_inode: |
1025 | free_pipe_info(inode); |
1026 | iput(inode); |
1027 | err: |
1028 | return ERR_PTR(err); |
1029 | } |
1030 | |
1031 | void free_write_pipe(struct file *f) |
1032 | { |
1033 | free_pipe_info(f->f_dentry->d_inode); |
1034 | path_put(&f->f_path); |
1035 | put_filp(f); |
1036 | } |
1037 | |
1038 | struct file *create_read_pipe(struct file *wrf, int flags) |
1039 | { |
1040 | /* Grab pipe from the writer */ |
1041 | struct file *f = alloc_file(&wrf->f_path, FMODE_READ, |
1042 | &read_pipefifo_fops); |
1043 | if (!f) |
1044 | return ERR_PTR(-ENFILE); |
1045 | |
1046 | path_get(&wrf->f_path); |
1047 | f->f_flags = O_RDONLY | (flags & O_NONBLOCK); |
1048 | |
1049 | return f; |
1050 | } |
1051 | |
1052 | int do_pipe_flags(int *fd, int flags) |
1053 | { |
1054 | struct file *fw, *fr; |
1055 | int error; |
1056 | int fdw, fdr; |
1057 | |
1058 | if (flags & ~(O_CLOEXEC | O_NONBLOCK)) |
1059 | return -EINVAL; |
1060 | |
1061 | fw = create_write_pipe(flags); |
1062 | if (IS_ERR(fw)) |
1063 | return PTR_ERR(fw); |
1064 | fr = create_read_pipe(fw, flags); |
1065 | error = PTR_ERR(fr); |
1066 | if (IS_ERR(fr)) |
1067 | goto err_write_pipe; |
1068 | |
1069 | error = get_unused_fd_flags(flags); |
1070 | if (error < 0) |
1071 | goto err_read_pipe; |
1072 | fdr = error; |
1073 | |
1074 | error = get_unused_fd_flags(flags); |
1075 | if (error < 0) |
1076 | goto err_fdr; |
1077 | fdw = error; |
1078 | |
1079 | audit_fd_pair(fdr, fdw); |
1080 | fd_install(fdr, fr); |
1081 | fd_install(fdw, fw); |
1082 | fd[0] = fdr; |
1083 | fd[1] = fdw; |
1084 | |
1085 | return 0; |
1086 | |
1087 | err_fdr: |
1088 | put_unused_fd(fdr); |
1089 | err_read_pipe: |
1090 | path_put(&fr->f_path); |
1091 | put_filp(fr); |
1092 | err_write_pipe: |
1093 | free_write_pipe(fw); |
1094 | return error; |
1095 | } |
1096 | |
1097 | /* |
1098 | * sys_pipe() is the normal C calling standard for creating |
1099 | * a pipe. It's not the way Unix traditionally does this, though. |
1100 | */ |
1101 | SYSCALL_DEFINE2(pipe2, int __user *, fildes, int, flags) |
1102 | { |
1103 | int fd[2]; |
1104 | int error; |
1105 | |
1106 | error = do_pipe_flags(fd, flags); |
1107 | if (!error) { |
1108 | if (copy_to_user(fildes, fd, sizeof(fd))) { |
1109 | sys_close(fd[0]); |
1110 | sys_close(fd[1]); |
1111 | error = -EFAULT; |
1112 | } |
1113 | } |
1114 | return error; |
1115 | } |
1116 | |
1117 | SYSCALL_DEFINE1(pipe, int __user *, fildes) |
1118 | { |
1119 | return sys_pipe2(fildes, 0); |
1120 | } |
1121 | |
1122 | /* |
1123 | * Allocate a new array of pipe buffers and copy the info over. Returns the |
1124 | * pipe size if successful, or return -ERROR on error. |
1125 | */ |
1126 | static long pipe_set_size(struct pipe_inode_info *pipe, unsigned long nr_pages) |
1127 | { |
1128 | struct pipe_buffer *bufs; |
1129 | |
1130 | /* |
1131 | * We can shrink the pipe, if arg >= pipe->nrbufs. Since we don't |
1132 | * expect a lot of shrink+grow operations, just free and allocate |
1133 | * again like we would do for growing. If the pipe currently |
1134 | * contains more buffers than arg, then return busy. |
1135 | */ |
1136 | if (nr_pages < pipe->nrbufs) |
1137 | return -EBUSY; |
1138 | |
1139 | bufs = kcalloc(nr_pages, sizeof(struct pipe_buffer), GFP_KERNEL); |
1140 | if (unlikely(!bufs)) |
1141 | return -ENOMEM; |
1142 | |
1143 | /* |
1144 | * The pipe array wraps around, so just start the new one at zero |
1145 | * and adjust the indexes. |
1146 | */ |
1147 | if (pipe->nrbufs) { |
1148 | unsigned int tail; |
1149 | unsigned int head; |
1150 | |
1151 | tail = pipe->curbuf + pipe->nrbufs; |
1152 | if (tail < pipe->buffers) |
1153 | tail = 0; |
1154 | else |
1155 | tail &= (pipe->buffers - 1); |
1156 | |
1157 | head = pipe->nrbufs - tail; |
1158 | if (head) |
1159 | memcpy(bufs, pipe->bufs + pipe->curbuf, head * sizeof(struct pipe_buffer)); |
1160 | if (tail) |
1161 | memcpy(bufs + head, pipe->bufs, tail * sizeof(struct pipe_buffer)); |
1162 | } |
1163 | |
1164 | pipe->curbuf = 0; |
1165 | kfree(pipe->bufs); |
1166 | pipe->bufs = bufs; |
1167 | pipe->buffers = nr_pages; |
1168 | return nr_pages * PAGE_SIZE; |
1169 | } |
1170 | |
1171 | /* |
1172 | * Currently we rely on the pipe array holding a power-of-2 number |
1173 | * of pages. |
1174 | */ |
1175 | static inline unsigned int round_pipe_size(unsigned int size) |
1176 | { |
1177 | unsigned long nr_pages; |
1178 | |
1179 | nr_pages = (size + PAGE_SIZE - 1) >> PAGE_SHIFT; |
1180 | return roundup_pow_of_two(nr_pages) << PAGE_SHIFT; |
1181 | } |
1182 | |
1183 | /* |
1184 | * This should work even if CONFIG_PROC_FS isn't set, as proc_dointvec_minmax |
1185 | * will return an error. |
1186 | */ |
1187 | int pipe_proc_fn(struct ctl_table *table, int write, void __user *buf, |
1188 | size_t *lenp, loff_t *ppos) |
1189 | { |
1190 | int ret; |
1191 | |
1192 | ret = proc_dointvec_minmax(table, write, buf, lenp, ppos); |
1193 | if (ret < 0 || !write) |
1194 | return ret; |
1195 | |
1196 | pipe_max_size = round_pipe_size(pipe_max_size); |
1197 | return ret; |
1198 | } |
1199 | |
1200 | long pipe_fcntl(struct file *file, unsigned int cmd, unsigned long arg) |
1201 | { |
1202 | struct pipe_inode_info *pipe; |
1203 | long ret; |
1204 | |
1205 | pipe = file->f_path.dentry->d_inode->i_pipe; |
1206 | if (!pipe) |
1207 | return -EBADF; |
1208 | |
1209 | mutex_lock(&pipe->inode->i_mutex); |
1210 | |
1211 | switch (cmd) { |
1212 | case F_SETPIPE_SZ: { |
1213 | unsigned int size, nr_pages; |
1214 | |
1215 | size = round_pipe_size(arg); |
1216 | nr_pages = size >> PAGE_SHIFT; |
1217 | |
1218 | ret = -EINVAL; |
1219 | if (!nr_pages) |
1220 | goto out; |
1221 | |
1222 | if (!capable(CAP_SYS_RESOURCE) && size > pipe_max_size) { |
1223 | ret = -EPERM; |
1224 | goto out; |
1225 | } |
1226 | ret = pipe_set_size(pipe, nr_pages); |
1227 | break; |
1228 | } |
1229 | case F_GETPIPE_SZ: |
1230 | ret = pipe->buffers * PAGE_SIZE; |
1231 | break; |
1232 | default: |
1233 | ret = -EINVAL; |
1234 | break; |
1235 | } |
1236 | |
1237 | out: |
1238 | mutex_unlock(&pipe->inode->i_mutex); |
1239 | return ret; |
1240 | } |
1241 | |
1242 | /* |
1243 | * pipefs should _never_ be mounted by userland - too much of security hassle, |
1244 | * no real gain from having the whole whorehouse mounted. So we don't need |
1245 | * any operations on the root directory. However, we need a non-trivial |
1246 | * d_name - pipe: will go nicely and kill the special-casing in procfs. |
1247 | */ |
1248 | static int pipefs_get_sb(struct file_system_type *fs_type, |
1249 | int flags, const char *dev_name, void *data, |
1250 | struct vfsmount *mnt) |
1251 | { |
1252 | return get_sb_pseudo(fs_type, "pipe:", NULL, PIPEFS_MAGIC, mnt); |
1253 | } |
1254 | |
1255 | static struct file_system_type pipe_fs_type = { |
1256 | .name = "pipefs", |
1257 | .get_sb = pipefs_get_sb, |
1258 | .kill_sb = kill_anon_super, |
1259 | }; |
1260 | |
1261 | static int __init init_pipe_fs(void) |
1262 | { |
1263 | int err = register_filesystem(&pipe_fs_type); |
1264 | |
1265 | if (!err) { |
1266 | pipe_mnt = kern_mount(&pipe_fs_type); |
1267 | if (IS_ERR(pipe_mnt)) { |
1268 | err = PTR_ERR(pipe_mnt); |
1269 | unregister_filesystem(&pipe_fs_type); |
1270 | } |
1271 | } |
1272 | return err; |
1273 | } |
1274 | |
1275 | static void __exit exit_pipe_fs(void) |
1276 | { |
1277 | unregister_filesystem(&pipe_fs_type); |
1278 | mntput(pipe_mnt); |
1279 | } |
1280 | |
1281 | fs_initcall(init_pipe_fs); |
1282 | module_exit(exit_pipe_fs); |
1283 |
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