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v4.17
   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/magic.h>
  18#include <linux/pipe_fs_i.h>
  19#include <linux/uio.h>
  20#include <linux/highmem.h>
  21#include <linux/pagemap.h>
  22#include <linux/audit.h>
  23#include <linux/syscalls.h>
  24#include <linux/fcntl.h>
  25#include <linux/memcontrol.h>
  26
  27#include <linux/uaccess.h>
  28#include <asm/ioctls.h>
  29
  30#include "internal.h"
  31
  32/*
  33 * The max size that a non-root user is allowed to grow the pipe. Can
  34 * be set by root in /proc/sys/fs/pipe-max-size
  35 */
  36unsigned int pipe_max_size = 1048576;
  37
  38/* Maximum allocatable pages per user. Hard limit is unset by default, soft
  39 * matches default values.
  40 */
  41unsigned long pipe_user_pages_hard;
  42unsigned long pipe_user_pages_soft = PIPE_DEF_BUFFERS * INR_OPEN_CUR;
  43
  44/*
  45 * We use a start+len construction, which provides full use of the 
  46 * allocated memory.
  47 * -- Florian Coosmann (FGC)
  48 * 
  49 * Reads with count = 0 should always return 0.
  50 * -- Julian Bradfield 1999-06-07.
  51 *
  52 * FIFOs and Pipes now generate SIGIO for both readers and writers.
  53 * -- Jeremy Elson <jelson@circlemud.org> 2001-08-16
  54 *
  55 * pipe_read & write cleanup
  56 * -- Manfred Spraul <manfred@colorfullife.com> 2002-05-09
  57 */
  58
  59static void pipe_lock_nested(struct pipe_inode_info *pipe, int subclass)
  60{
  61	if (pipe->files)
  62		mutex_lock_nested(&pipe->mutex, subclass);
  63}
  64
  65void pipe_lock(struct pipe_inode_info *pipe)
  66{
  67	/*
  68	 * pipe_lock() nests non-pipe inode locks (for writing to a file)
  69	 */
  70	pipe_lock_nested(pipe, I_MUTEX_PARENT);
  71}
  72EXPORT_SYMBOL(pipe_lock);
  73
  74void pipe_unlock(struct pipe_inode_info *pipe)
  75{
  76	if (pipe->files)
  77		mutex_unlock(&pipe->mutex);
  78}
  79EXPORT_SYMBOL(pipe_unlock);
  80
  81static inline void __pipe_lock(struct pipe_inode_info *pipe)
  82{
  83	mutex_lock_nested(&pipe->mutex, I_MUTEX_PARENT);
  84}
  85
  86static inline void __pipe_unlock(struct pipe_inode_info *pipe)
  87{
  88	mutex_unlock(&pipe->mutex);
  89}
  90
  91void pipe_double_lock(struct pipe_inode_info *pipe1,
  92		      struct pipe_inode_info *pipe2)
  93{
  94	BUG_ON(pipe1 == pipe2);
  95
  96	if (pipe1 < pipe2) {
  97		pipe_lock_nested(pipe1, I_MUTEX_PARENT);
  98		pipe_lock_nested(pipe2, I_MUTEX_CHILD);
  99	} else {
 100		pipe_lock_nested(pipe2, I_MUTEX_PARENT);
 101		pipe_lock_nested(pipe1, I_MUTEX_CHILD);
 102	}
 103}
 104
 105/* Drop the inode semaphore and wait for a pipe event, atomically */
 106void pipe_wait(struct pipe_inode_info *pipe)
 107{
 108	DEFINE_WAIT(wait);
 109
 110	/*
 111	 * Pipes are system-local resources, so sleeping on them
 112	 * is considered a noninteractive wait:
 113	 */
 114	prepare_to_wait(&pipe->wait, &wait, TASK_INTERRUPTIBLE);
 115	pipe_unlock(pipe);
 116	schedule();
 117	finish_wait(&pipe->wait, &wait);
 118	pipe_lock(pipe);
 119}
 120
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 121static void anon_pipe_buf_release(struct pipe_inode_info *pipe,
 122				  struct pipe_buffer *buf)
 123{
 124	struct page *page = buf->page;
 125
 126	/*
 127	 * If nobody else uses this page, and we don't already have a
 128	 * temporary page, let's keep track of it as a one-deep
 129	 * allocation cache. (Otherwise just release our reference to it)
 130	 */
 131	if (page_count(page) == 1 && !pipe->tmp_page)
 132		pipe->tmp_page = page;
 133	else
 134		put_page(page);
 135}
 136
 137static int anon_pipe_buf_steal(struct pipe_inode_info *pipe,
 138			       struct pipe_buffer *buf)
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 139{
 140	struct page *page = buf->page;
 141
 142	if (page_count(page) == 1) {
 143		if (memcg_kmem_enabled())
 144			memcg_kmem_uncharge(page, 0);
 145		__SetPageLocked(page);
 146		return 0;
 147	}
 148	return 1;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 149}
 
 150
 151/**
 152 * generic_pipe_buf_steal - attempt to take ownership of a &pipe_buffer
 153 * @pipe:	the pipe that the buffer belongs to
 154 * @buf:	the buffer to attempt to steal
 155 *
 156 * Description:
 157 *	This function attempts to steal the &struct page attached to
 158 *	@buf. If successful, this function returns 0 and returns with
 159 *	the page locked. The caller may then reuse the page for whatever
 160 *	he wishes; the typical use is insertion into a different file
 161 *	page cache.
 162 */
 163int generic_pipe_buf_steal(struct pipe_inode_info *pipe,
 164			   struct pipe_buffer *buf)
 165{
 166	struct page *page = buf->page;
 167
 168	/*
 169	 * A reference of one is golden, that means that the owner of this
 170	 * page is the only one holding a reference to it. lock the page
 171	 * and return OK.
 172	 */
 173	if (page_count(page) == 1) {
 174		lock_page(page);
 175		return 0;
 176	}
 177
 178	return 1;
 179}
 180EXPORT_SYMBOL(generic_pipe_buf_steal);
 181
 182/**
 183 * generic_pipe_buf_get - get a reference to a &struct pipe_buffer
 184 * @pipe:	the pipe that the buffer belongs to
 185 * @buf:	the buffer to get a reference to
 186 *
 187 * Description:
 188 *	This function grabs an extra reference to @buf. It's used in
 189 *	in the tee() system call, when we duplicate the buffers in one
 190 *	pipe into another.
 191 */
 192void generic_pipe_buf_get(struct pipe_inode_info *pipe, struct pipe_buffer *buf)
 193{
 194	get_page(buf->page);
 195}
 196EXPORT_SYMBOL(generic_pipe_buf_get);
 197
 198/**
 199 * generic_pipe_buf_confirm - verify contents of the pipe buffer
 200 * @info:	the pipe that the buffer belongs to
 201 * @buf:	the buffer to confirm
 202 *
 203 * Description:
 204 *	This function does nothing, because the generic pipe code uses
 205 *	pages that are always good when inserted into the pipe.
 206 */
 207int generic_pipe_buf_confirm(struct pipe_inode_info *info,
 208			     struct pipe_buffer *buf)
 209{
 210	return 0;
 211}
 212EXPORT_SYMBOL(generic_pipe_buf_confirm);
 213
 214/**
 215 * generic_pipe_buf_release - put a reference to a &struct pipe_buffer
 216 * @pipe:	the pipe that the buffer belongs to
 217 * @buf:	the buffer to put a reference to
 218 *
 219 * Description:
 220 *	This function releases a reference to @buf.
 221 */
 222void generic_pipe_buf_release(struct pipe_inode_info *pipe,
 223			      struct pipe_buffer *buf)
 224{
 225	put_page(buf->page);
 226}
 227EXPORT_SYMBOL(generic_pipe_buf_release);
 228
 229static const struct pipe_buf_operations anon_pipe_buf_ops = {
 230	.can_merge = 1,
 
 
 231	.confirm = generic_pipe_buf_confirm,
 232	.release = anon_pipe_buf_release,
 233	.steal = anon_pipe_buf_steal,
 234	.get = generic_pipe_buf_get,
 235};
 236
 237static const struct pipe_buf_operations packet_pipe_buf_ops = {
 238	.can_merge = 0,
 239	.confirm = generic_pipe_buf_confirm,
 240	.release = anon_pipe_buf_release,
 241	.steal = anon_pipe_buf_steal,
 242	.get = generic_pipe_buf_get,
 243};
 244
 245static ssize_t
 246pipe_read(struct kiocb *iocb, struct iov_iter *to)
 
 247{
 248	size_t total_len = iov_iter_count(to);
 249	struct file *filp = iocb->ki_filp;
 250	struct pipe_inode_info *pipe = filp->private_data;
 
 251	int do_wakeup;
 252	ssize_t ret;
 
 
 253
 
 254	/* Null read succeeds. */
 255	if (unlikely(total_len == 0))
 256		return 0;
 257
 258	do_wakeup = 0;
 259	ret = 0;
 260	__pipe_lock(pipe);
 
 261	for (;;) {
 262		int bufs = pipe->nrbufs;
 263		if (bufs) {
 264			int curbuf = pipe->curbuf;
 265			struct pipe_buffer *buf = pipe->bufs + curbuf;
 
 
 266			size_t chars = buf->len;
 267			size_t written;
 268			int error;
 269
 270			if (chars > total_len)
 271				chars = total_len;
 272
 273			error = pipe_buf_confirm(pipe, buf);
 274			if (error) {
 275				if (!ret)
 276					ret = error;
 277				break;
 278			}
 279
 280			written = copy_page_to_iter(buf->page, buf->offset, chars, to);
 281			if (unlikely(written < chars)) {
 
 
 
 
 
 
 
 
 
 
 
 282				if (!ret)
 283					ret = -EFAULT;
 284				break;
 285			}
 286			ret += chars;
 287			buf->offset += chars;
 288			buf->len -= chars;
 289
 290			/* Was it a packet buffer? Clean up and exit */
 291			if (buf->flags & PIPE_BUF_FLAG_PACKET) {
 292				total_len = chars;
 293				buf->len = 0;
 294			}
 295
 296			if (!buf->len) {
 297				pipe_buf_release(pipe, buf);
 
 298				curbuf = (curbuf + 1) & (pipe->buffers - 1);
 299				pipe->curbuf = curbuf;
 300				pipe->nrbufs = --bufs;
 301				do_wakeup = 1;
 302			}
 303			total_len -= chars;
 304			if (!total_len)
 305				break;	/* common path: read succeeded */
 306		}
 307		if (bufs)	/* More to do? */
 308			continue;
 309		if (!pipe->writers)
 310			break;
 311		if (!pipe->waiting_writers) {
 312			/* syscall merging: Usually we must not sleep
 313			 * if O_NONBLOCK is set, or if we got some data.
 314			 * But if a writer sleeps in kernel space, then
 315			 * we can wait for that data without violating POSIX.
 316			 */
 317			if (ret)
 318				break;
 319			if (filp->f_flags & O_NONBLOCK) {
 320				ret = -EAGAIN;
 321				break;
 322			}
 323		}
 324		if (signal_pending(current)) {
 325			if (!ret)
 326				ret = -ERESTARTSYS;
 327			break;
 328		}
 329		if (do_wakeup) {
 330			wake_up_interruptible_sync_poll(&pipe->wait, EPOLLOUT | EPOLLWRNORM);
 331 			kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT);
 332		}
 333		pipe_wait(pipe);
 334	}
 335	__pipe_unlock(pipe);
 336
 337	/* Signal writers asynchronously that there is more room. */
 338	if (do_wakeup) {
 339		wake_up_interruptible_sync_poll(&pipe->wait, EPOLLOUT | EPOLLWRNORM);
 340		kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT);
 341	}
 342	if (ret > 0)
 343		file_accessed(filp);
 344	return ret;
 345}
 346
 347static inline int is_packetized(struct file *file)
 348{
 349	return (file->f_flags & O_DIRECT) != 0;
 350}
 351
 352static ssize_t
 353pipe_write(struct kiocb *iocb, struct iov_iter *from)
 
 354{
 355	struct file *filp = iocb->ki_filp;
 356	struct pipe_inode_info *pipe = filp->private_data;
 357	ssize_t ret = 0;
 358	int do_wakeup = 0;
 359	size_t total_len = iov_iter_count(from);
 
 
 360	ssize_t chars;
 361
 
 362	/* Null write succeeds. */
 363	if (unlikely(total_len == 0))
 364		return 0;
 365
 366	__pipe_lock(pipe);
 
 
 
 367
 368	if (!pipe->readers) {
 369		send_sig(SIGPIPE, current, 0);
 370		ret = -EPIPE;
 371		goto out;
 372	}
 373
 374	/* We try to merge small writes */
 375	chars = total_len & (PAGE_SIZE-1); /* size of the last buffer */
 376	if (pipe->nrbufs && chars != 0) {
 377		int lastbuf = (pipe->curbuf + pipe->nrbufs - 1) &
 378							(pipe->buffers - 1);
 379		struct pipe_buffer *buf = pipe->bufs + lastbuf;
 
 380		int offset = buf->offset + buf->len;
 381
 382		if (buf->ops->can_merge && offset + chars <= PAGE_SIZE) {
 383			ret = pipe_buf_confirm(pipe, buf);
 384			if (ret)
 
 
 
 385				goto out;
 386
 387			ret = copy_page_from_iter(buf->page, offset, chars, from);
 388			if (unlikely(ret < chars)) {
 389				ret = -EFAULT;
 
 
 
 
 
 
 
 
 
 
 390				goto out;
 391			}
 392			do_wakeup = 1;
 393			buf->len += ret;
 394			if (!iov_iter_count(from))
 
 395				goto out;
 396		}
 397	}
 398
 399	for (;;) {
 400		int bufs;
 401
 402		if (!pipe->readers) {
 403			send_sig(SIGPIPE, current, 0);
 404			if (!ret)
 405				ret = -EPIPE;
 406			break;
 407		}
 408		bufs = pipe->nrbufs;
 409		if (bufs < pipe->buffers) {
 410			int newbuf = (pipe->curbuf + bufs) & (pipe->buffers-1);
 411			struct pipe_buffer *buf = pipe->bufs + newbuf;
 412			struct page *page = pipe->tmp_page;
 413			int copied;
 
 414
 415			if (!page) {
 416				page = alloc_page(GFP_HIGHUSER | __GFP_ACCOUNT);
 417				if (unlikely(!page)) {
 418					ret = ret ? : -ENOMEM;
 419					break;
 420				}
 421				pipe->tmp_page = page;
 422			}
 423			/* Always wake up, even if the copy fails. Otherwise
 424			 * we lock up (O_NONBLOCK-)readers that sleep due to
 425			 * syscall merging.
 426			 * FIXME! Is this really true?
 427			 */
 428			do_wakeup = 1;
 429			copied = copy_page_from_iter(page, 0, PAGE_SIZE, from);
 430			if (unlikely(copied < PAGE_SIZE && iov_iter_count(from))) {
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 431				if (!ret)
 432					ret = -EFAULT;
 433				break;
 434			}
 435			ret += copied;
 436
 437			/* Insert it into the buffer array */
 438			buf->page = page;
 439			buf->ops = &anon_pipe_buf_ops;
 440			buf->offset = 0;
 441			buf->len = copied;
 442			buf->flags = 0;
 443			if (is_packetized(filp)) {
 444				buf->ops = &packet_pipe_buf_ops;
 445				buf->flags = PIPE_BUF_FLAG_PACKET;
 446			}
 447			pipe->nrbufs = ++bufs;
 448			pipe->tmp_page = NULL;
 449
 450			if (!iov_iter_count(from))
 
 451				break;
 452		}
 453		if (bufs < pipe->buffers)
 454			continue;
 455		if (filp->f_flags & O_NONBLOCK) {
 456			if (!ret)
 457				ret = -EAGAIN;
 458			break;
 459		}
 460		if (signal_pending(current)) {
 461			if (!ret)
 462				ret = -ERESTARTSYS;
 463			break;
 464		}
 465		if (do_wakeup) {
 466			wake_up_interruptible_sync_poll(&pipe->wait, EPOLLIN | EPOLLRDNORM);
 467			kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
 468			do_wakeup = 0;
 469		}
 470		pipe->waiting_writers++;
 471		pipe_wait(pipe);
 472		pipe->waiting_writers--;
 473	}
 474out:
 475	__pipe_unlock(pipe);
 476	if (do_wakeup) {
 477		wake_up_interruptible_sync_poll(&pipe->wait, EPOLLIN | EPOLLRDNORM);
 478		kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
 479	}
 480	if (ret > 0 && sb_start_write_trylock(file_inode(filp)->i_sb)) {
 481		int err = file_update_time(filp);
 482		if (err)
 483			ret = err;
 484		sb_end_write(file_inode(filp)->i_sb);
 485	}
 486	return ret;
 487}
 488
 
 
 
 
 
 
 
 
 
 
 
 
 
 489static long pipe_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 490{
 491	struct pipe_inode_info *pipe = filp->private_data;
 
 492	int count, buf, nrbufs;
 493
 494	switch (cmd) {
 495		case FIONREAD:
 496			__pipe_lock(pipe);
 
 497			count = 0;
 498			buf = pipe->curbuf;
 499			nrbufs = pipe->nrbufs;
 500			while (--nrbufs >= 0) {
 501				count += pipe->bufs[buf].len;
 502				buf = (buf+1) & (pipe->buffers - 1);
 503			}
 504			__pipe_unlock(pipe);
 505
 506			return put_user(count, (int __user *)arg);
 507		default:
 508			return -ENOIOCTLCMD;
 509	}
 510}
 511
 512/* No kernel lock held - fine */
 513static __poll_t
 514pipe_poll(struct file *filp, poll_table *wait)
 515{
 516	__poll_t mask;
 517	struct pipe_inode_info *pipe = filp->private_data;
 
 518	int nrbufs;
 519
 520	poll_wait(filp, &pipe->wait, wait);
 521
 522	/* Reading only -- no need for acquiring the semaphore.  */
 523	nrbufs = pipe->nrbufs;
 524	mask = 0;
 525	if (filp->f_mode & FMODE_READ) {
 526		mask = (nrbufs > 0) ? EPOLLIN | EPOLLRDNORM : 0;
 527		if (!pipe->writers && filp->f_version != pipe->w_counter)
 528			mask |= EPOLLHUP;
 529	}
 530
 531	if (filp->f_mode & FMODE_WRITE) {
 532		mask |= (nrbufs < pipe->buffers) ? EPOLLOUT | EPOLLWRNORM : 0;
 533		/*
 534		 * Most Unices do not set EPOLLERR for FIFOs but on Linux they
 535		 * behave exactly like pipes for poll().
 536		 */
 537		if (!pipe->readers)
 538			mask |= EPOLLERR;
 539	}
 540
 541	return mask;
 542}
 543
 544static void put_pipe_info(struct inode *inode, struct pipe_inode_info *pipe)
 
 545{
 546	int kill = 0;
 547
 548	spin_lock(&inode->i_lock);
 549	if (!--pipe->files) {
 550		inode->i_pipe = NULL;
 551		kill = 1;
 
 
 
 
 
 
 
 552	}
 553	spin_unlock(&inode->i_lock);
 554
 555	if (kill)
 556		free_pipe_info(pipe);
 557}
 558
 559static int
 560pipe_release(struct inode *inode, struct file *file)
 561{
 562	struct pipe_inode_info *pipe = file->private_data;
 
 563
 564	__pipe_lock(pipe);
 565	if (file->f_mode & FMODE_READ)
 566		pipe->readers--;
 567	if (file->f_mode & FMODE_WRITE)
 568		pipe->writers--;
 569
 570	if (pipe->readers || pipe->writers) {
 571		wake_up_interruptible_sync_poll(&pipe->wait, EPOLLIN | EPOLLOUT | EPOLLRDNORM | EPOLLWRNORM | EPOLLERR | EPOLLHUP);
 572		kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
 573		kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT);
 574	}
 575	__pipe_unlock(pipe);
 576
 577	put_pipe_info(inode, pipe);
 578	return 0;
 579}
 580
 
 581static int
 582pipe_fasync(int fd, struct file *filp, int on)
 583{
 584	struct pipe_inode_info *pipe = filp->private_data;
 585	int retval = 0;
 
 
 
 
 
 
 
 
 586
 587	__pipe_lock(pipe);
 588	if (filp->f_mode & FMODE_READ)
 589		retval = fasync_helper(fd, filp, on, &pipe->fasync_readers);
 590	if ((filp->f_mode & FMODE_WRITE) && retval >= 0) {
 
 
 
 
 
 
 591		retval = fasync_helper(fd, filp, on, &pipe->fasync_writers);
 592		if (retval < 0 && (filp->f_mode & FMODE_READ))
 593			/* this can happen only if on == T */
 594			fasync_helper(-1, filp, 0, &pipe->fasync_readers);
 595	}
 596	__pipe_unlock(pipe);
 597	return retval;
 598}
 599
 600static unsigned long account_pipe_buffers(struct user_struct *user,
 601                                 unsigned long old, unsigned long new)
 
 602{
 603	return atomic_long_add_return(new - old, &user->pipe_bufs);
 604}
 605
 606static bool too_many_pipe_buffers_soft(unsigned long user_bufs)
 
 607{
 608	unsigned long soft_limit = READ_ONCE(pipe_user_pages_soft);
 609
 610	return soft_limit && user_bufs > soft_limit;
 611}
 612
 613static bool too_many_pipe_buffers_hard(unsigned long user_bufs)
 
 614{
 615	unsigned long hard_limit = READ_ONCE(pipe_user_pages_hard);
 616
 617	return hard_limit && user_bufs > hard_limit;
 
 
 618}
 619
 620static bool is_unprivileged_user(void)
 
 621{
 622	return !capable(CAP_SYS_RESOURCE) && !capable(CAP_SYS_ADMIN);
 
 
 
 
 
 
 
 
 
 
 
 623}
 624
 625struct pipe_inode_info *alloc_pipe_info(void)
 
 626{
 627	struct pipe_inode_info *pipe;
 628	unsigned long pipe_bufs = PIPE_DEF_BUFFERS;
 629	struct user_struct *user = get_current_user();
 630	unsigned long user_bufs;
 631	unsigned int max_size = READ_ONCE(pipe_max_size);
 632
 633	pipe = kzalloc(sizeof(struct pipe_inode_info), GFP_KERNEL_ACCOUNT);
 634	if (pipe == NULL)
 635		goto out_free_uid;
 
 
 
 
 
 
 636
 637	if (pipe_bufs * PAGE_SIZE > max_size && !capable(CAP_SYS_RESOURCE))
 638		pipe_bufs = max_size >> PAGE_SHIFT;
 
 
 639
 640	user_bufs = account_pipe_buffers(user, 0, pipe_bufs);
 641
 642	if (too_many_pipe_buffers_soft(user_bufs) && is_unprivileged_user()) {
 643		user_bufs = account_pipe_buffers(user, pipe_bufs, 1);
 644		pipe_bufs = 1;
 
 
 
 645	}
 646
 647	if (too_many_pipe_buffers_hard(user_bufs) && is_unprivileged_user())
 648		goto out_revert_acct;
 649
 650	pipe->bufs = kcalloc(pipe_bufs, sizeof(struct pipe_buffer),
 651			     GFP_KERNEL_ACCOUNT);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 652
 653	if (pipe->bufs) {
 654		init_waitqueue_head(&pipe->wait);
 655		pipe->r_counter = pipe->w_counter = 1;
 656		pipe->buffers = pipe_bufs;
 657		pipe->user = user;
 658		mutex_init(&pipe->mutex);
 659		return pipe;
 
 
 
 
 660	}
 661
 662out_revert_acct:
 663	(void) account_pipe_buffers(user, pipe_bufs, 0);
 664	kfree(pipe);
 665out_free_uid:
 666	free_uid(user);
 667	return NULL;
 668}
 669
 670void free_pipe_info(struct pipe_inode_info *pipe)
 671{
 672	int i;
 673
 674	(void) account_pipe_buffers(pipe->user, pipe->buffers, 0);
 675	free_uid(pipe->user);
 676	for (i = 0; i < pipe->buffers; i++) {
 677		struct pipe_buffer *buf = pipe->bufs + i;
 678		if (buf->ops)
 679			pipe_buf_release(pipe, buf);
 680	}
 681	if (pipe->tmp_page)
 682		__free_page(pipe->tmp_page);
 683	kfree(pipe->bufs);
 684	kfree(pipe);
 685}
 686
 
 
 
 
 
 
 687static struct vfsmount *pipe_mnt __read_mostly;
 688
 689/*
 690 * pipefs_dname() is called from d_path().
 691 */
 692static char *pipefs_dname(struct dentry *dentry, char *buffer, int buflen)
 693{
 694	return dynamic_dname(dentry, buffer, buflen, "pipe:[%lu]",
 695				d_inode(dentry)->i_ino);
 696}
 697
 698static const struct dentry_operations pipefs_dentry_operations = {
 699	.d_dname	= pipefs_dname,
 700};
 701
 702static struct inode * get_pipe_inode(void)
 703{
 704	struct inode *inode = new_inode_pseudo(pipe_mnt->mnt_sb);
 705	struct pipe_inode_info *pipe;
 706
 707	if (!inode)
 708		goto fail_inode;
 709
 710	inode->i_ino = get_next_ino();
 711
 712	pipe = alloc_pipe_info();
 713	if (!pipe)
 714		goto fail_iput;
 715
 716	inode->i_pipe = pipe;
 717	pipe->files = 2;
 718	pipe->readers = pipe->writers = 1;
 719	inode->i_fop = &pipefifo_fops;
 720
 721	/*
 722	 * Mark the inode dirty from the very beginning,
 723	 * that way it will never be moved to the dirty
 724	 * list because "mark_inode_dirty()" will think
 725	 * that it already _is_ on the dirty list.
 726	 */
 727	inode->i_state = I_DIRTY;
 728	inode->i_mode = S_IFIFO | S_IRUSR | S_IWUSR;
 729	inode->i_uid = current_fsuid();
 730	inode->i_gid = current_fsgid();
 731	inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode);
 732
 733	return inode;
 734
 735fail_iput:
 736	iput(inode);
 737
 738fail_inode:
 739	return NULL;
 740}
 741
 742int create_pipe_files(struct file **res, int flags)
 743{
 744	int err;
 745	struct inode *inode = get_pipe_inode();
 746	struct file *f;
 747	struct path path;
 
 748
 
 
 749	if (!inode)
 750		return -ENFILE;
 751
 752	err = -ENOMEM;
 753	path.dentry = d_alloc_pseudo(pipe_mnt->mnt_sb, &empty_name);
 754	if (!path.dentry)
 755		goto err_inode;
 756	path.mnt = mntget(pipe_mnt);
 757
 758	d_instantiate(path.dentry, inode);
 759
 760	f = alloc_file(&path, FMODE_WRITE, &pipefifo_fops);
 761	if (IS_ERR(f)) {
 762		err = PTR_ERR(f);
 763		goto err_dentry;
 764	}
 765
 766	f->f_flags = O_WRONLY | (flags & (O_NONBLOCK | O_DIRECT));
 767	f->private_data = inode->i_pipe;
 768
 769	res[0] = alloc_file(&path, FMODE_READ, &pipefifo_fops);
 770	if (IS_ERR(res[0])) {
 771		err = PTR_ERR(res[0]);
 772		goto err_file;
 773	}
 774
 775	path_get(&path);
 776	res[0]->private_data = inode->i_pipe;
 777	res[0]->f_flags = O_RDONLY | (flags & O_NONBLOCK);
 778	res[1] = f;
 779	return 0;
 780
 781err_file:
 782	put_filp(f);
 783err_dentry:
 784	free_pipe_info(inode->i_pipe);
 785	path_put(&path);
 786	return err;
 787
 788err_inode:
 789	free_pipe_info(inode->i_pipe);
 790	iput(inode);
 791	return err;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 792}
 793
 794static int __do_pipe_flags(int *fd, struct file **files, int flags)
 795{
 
 796	int error;
 797	int fdw, fdr;
 798
 799	if (flags & ~(O_CLOEXEC | O_NONBLOCK | O_DIRECT))
 800		return -EINVAL;
 801
 802	error = create_pipe_files(files, flags);
 803	if (error)
 804		return error;
 
 
 
 
 805
 806	error = get_unused_fd_flags(flags);
 807	if (error < 0)
 808		goto err_read_pipe;
 809	fdr = error;
 810
 811	error = get_unused_fd_flags(flags);
 812	if (error < 0)
 813		goto err_fdr;
 814	fdw = error;
 815
 816	audit_fd_pair(fdr, fdw);
 
 
 817	fd[0] = fdr;
 818	fd[1] = fdw;
 
 819	return 0;
 820
 821 err_fdr:
 822	put_unused_fd(fdr);
 823 err_read_pipe:
 824	fput(files[0]);
 825	fput(files[1]);
 826	return error;
 827}
 828
 829int do_pipe_flags(int *fd, int flags)
 830{
 831	struct file *files[2];
 832	int error = __do_pipe_flags(fd, files, flags);
 833	if (!error) {
 834		fd_install(fd[0], files[0]);
 835		fd_install(fd[1], files[1]);
 836	}
 837	return error;
 838}
 839
 840/*
 841 * sys_pipe() is the normal C calling standard for creating
 842 * a pipe. It's not the way Unix traditionally does this, though.
 843 */
 844static int do_pipe2(int __user *fildes, int flags)
 845{
 846	struct file *files[2];
 847	int fd[2];
 848	int error;
 849
 850	error = __do_pipe_flags(fd, files, flags);
 851	if (!error) {
 852		if (unlikely(copy_to_user(fildes, fd, sizeof(fd)))) {
 853			fput(files[0]);
 854			fput(files[1]);
 855			put_unused_fd(fd[0]);
 856			put_unused_fd(fd[1]);
 857			error = -EFAULT;
 858		} else {
 859			fd_install(fd[0], files[0]);
 860			fd_install(fd[1], files[1]);
 861		}
 862	}
 863	return error;
 864}
 865
 866SYSCALL_DEFINE2(pipe2, int __user *, fildes, int, flags)
 867{
 868	return do_pipe2(fildes, flags);
 869}
 870
 871SYSCALL_DEFINE1(pipe, int __user *, fildes)
 872{
 873	return do_pipe2(fildes, 0);
 874}
 875
 876static int wait_for_partner(struct pipe_inode_info *pipe, unsigned int *cnt)
 877{
 878	int cur = *cnt;	
 879
 880	while (cur == *cnt) {
 881		pipe_wait(pipe);
 882		if (signal_pending(current))
 883			break;
 884	}
 885	return cur == *cnt ? -ERESTARTSYS : 0;
 886}
 887
 888static void wake_up_partner(struct pipe_inode_info *pipe)
 889{
 890	wake_up_interruptible(&pipe->wait);
 891}
 892
 893static int fifo_open(struct inode *inode, struct file *filp)
 894{
 895	struct pipe_inode_info *pipe;
 896	bool is_pipe = inode->i_sb->s_magic == PIPEFS_MAGIC;
 897	int ret;
 898
 899	filp->f_version = 0;
 900
 901	spin_lock(&inode->i_lock);
 902	if (inode->i_pipe) {
 903		pipe = inode->i_pipe;
 904		pipe->files++;
 905		spin_unlock(&inode->i_lock);
 906	} else {
 907		spin_unlock(&inode->i_lock);
 908		pipe = alloc_pipe_info();
 909		if (!pipe)
 910			return -ENOMEM;
 911		pipe->files = 1;
 912		spin_lock(&inode->i_lock);
 913		if (unlikely(inode->i_pipe)) {
 914			inode->i_pipe->files++;
 915			spin_unlock(&inode->i_lock);
 916			free_pipe_info(pipe);
 917			pipe = inode->i_pipe;
 918		} else {
 919			inode->i_pipe = pipe;
 920			spin_unlock(&inode->i_lock);
 921		}
 922	}
 923	filp->private_data = pipe;
 924	/* OK, we have a pipe and it's pinned down */
 925
 926	__pipe_lock(pipe);
 927
 928	/* We can only do regular read/write on fifos */
 929	filp->f_mode &= (FMODE_READ | FMODE_WRITE);
 930
 931	switch (filp->f_mode) {
 932	case FMODE_READ:
 933	/*
 934	 *  O_RDONLY
 935	 *  POSIX.1 says that O_NONBLOCK means return with the FIFO
 936	 *  opened, even when there is no process writing the FIFO.
 937	 */
 938		pipe->r_counter++;
 939		if (pipe->readers++ == 0)
 940			wake_up_partner(pipe);
 941
 942		if (!is_pipe && !pipe->writers) {
 943			if ((filp->f_flags & O_NONBLOCK)) {
 944				/* suppress EPOLLHUP until we have
 945				 * seen a writer */
 946				filp->f_version = pipe->w_counter;
 947			} else {
 948				if (wait_for_partner(pipe, &pipe->w_counter))
 949					goto err_rd;
 950			}
 951		}
 952		break;
 953	
 954	case FMODE_WRITE:
 955	/*
 956	 *  O_WRONLY
 957	 *  POSIX.1 says that O_NONBLOCK means return -1 with
 958	 *  errno=ENXIO when there is no process reading the FIFO.
 959	 */
 960		ret = -ENXIO;
 961		if (!is_pipe && (filp->f_flags & O_NONBLOCK) && !pipe->readers)
 962			goto err;
 963
 964		pipe->w_counter++;
 965		if (!pipe->writers++)
 966			wake_up_partner(pipe);
 967
 968		if (!is_pipe && !pipe->readers) {
 969			if (wait_for_partner(pipe, &pipe->r_counter))
 970				goto err_wr;
 971		}
 972		break;
 973	
 974	case FMODE_READ | FMODE_WRITE:
 975	/*
 976	 *  O_RDWR
 977	 *  POSIX.1 leaves this case "undefined" when O_NONBLOCK is set.
 978	 *  This implementation will NEVER block on a O_RDWR open, since
 979	 *  the process can at least talk to itself.
 980	 */
 981
 982		pipe->readers++;
 983		pipe->writers++;
 984		pipe->r_counter++;
 985		pipe->w_counter++;
 986		if (pipe->readers == 1 || pipe->writers == 1)
 987			wake_up_partner(pipe);
 988		break;
 989
 990	default:
 991		ret = -EINVAL;
 992		goto err;
 993	}
 994
 995	/* Ok! */
 996	__pipe_unlock(pipe);
 997	return 0;
 998
 999err_rd:
1000	if (!--pipe->readers)
1001		wake_up_interruptible(&pipe->wait);
1002	ret = -ERESTARTSYS;
1003	goto err;
1004
1005err_wr:
1006	if (!--pipe->writers)
1007		wake_up_interruptible(&pipe->wait);
1008	ret = -ERESTARTSYS;
1009	goto err;
1010
1011err:
1012	__pipe_unlock(pipe);
1013
1014	put_pipe_info(inode, pipe);
1015	return ret;
1016}
1017
1018const struct file_operations pipefifo_fops = {
1019	.open		= fifo_open,
1020	.llseek		= no_llseek,
1021	.read_iter	= pipe_read,
1022	.write_iter	= pipe_write,
1023	.poll		= pipe_poll,
1024	.unlocked_ioctl	= pipe_ioctl,
1025	.release	= pipe_release,
1026	.fasync		= pipe_fasync,
1027};
1028
1029/*
1030 * Currently we rely on the pipe array holding a power-of-2 number
1031 * of pages. Returns 0 on error.
1032 */
1033unsigned int round_pipe_size(unsigned long size)
1034{
1035	if (size > (1U << 31))
1036		return 0;
1037
1038	/* Minimum pipe size, as required by POSIX */
1039	if (size < PAGE_SIZE)
1040		return PAGE_SIZE;
1041
1042	return roundup_pow_of_two(size);
1043}
1044
1045/*
1046 * Allocate a new array of pipe buffers and copy the info over. Returns the
1047 * pipe size if successful, or return -ERROR on error.
1048 */
1049static long pipe_set_size(struct pipe_inode_info *pipe, unsigned long arg)
1050{
1051	struct pipe_buffer *bufs;
1052	unsigned int size, nr_pages;
1053	unsigned long user_bufs;
1054	long ret = 0;
1055
1056	size = round_pipe_size(arg);
1057	nr_pages = size >> PAGE_SHIFT;
1058
1059	if (!nr_pages)
1060		return -EINVAL;
1061
1062	/*
1063	 * If trying to increase the pipe capacity, check that an
1064	 * unprivileged user is not trying to exceed various limits
1065	 * (soft limit check here, hard limit check just below).
1066	 * Decreasing the pipe capacity is always permitted, even
1067	 * if the user is currently over a limit.
1068	 */
1069	if (nr_pages > pipe->buffers &&
1070			size > pipe_max_size && !capable(CAP_SYS_RESOURCE))
1071		return -EPERM;
1072
1073	user_bufs = account_pipe_buffers(pipe->user, pipe->buffers, nr_pages);
1074
1075	if (nr_pages > pipe->buffers &&
1076			(too_many_pipe_buffers_hard(user_bufs) ||
1077			 too_many_pipe_buffers_soft(user_bufs)) &&
1078			is_unprivileged_user()) {
1079		ret = -EPERM;
1080		goto out_revert_acct;
1081	}
1082
1083	/*
1084	 * We can shrink the pipe, if arg >= pipe->nrbufs. Since we don't
1085	 * expect a lot of shrink+grow operations, just free and allocate
1086	 * again like we would do for growing. If the pipe currently
1087	 * contains more buffers than arg, then return busy.
1088	 */
1089	if (nr_pages < pipe->nrbufs) {
1090		ret = -EBUSY;
1091		goto out_revert_acct;
1092	}
1093
1094	bufs = kcalloc(nr_pages, sizeof(*bufs),
1095		       GFP_KERNEL_ACCOUNT | __GFP_NOWARN);
1096	if (unlikely(!bufs)) {
1097		ret = -ENOMEM;
1098		goto out_revert_acct;
1099	}
1100
1101	/*
1102	 * The pipe array wraps around, so just start the new one at zero
1103	 * and adjust the indexes.
1104	 */
1105	if (pipe->nrbufs) {
1106		unsigned int tail;
1107		unsigned int head;
1108
1109		tail = pipe->curbuf + pipe->nrbufs;
1110		if (tail < pipe->buffers)
1111			tail = 0;
1112		else
1113			tail &= (pipe->buffers - 1);
1114
1115		head = pipe->nrbufs - tail;
1116		if (head)
1117			memcpy(bufs, pipe->bufs + pipe->curbuf, head * sizeof(struct pipe_buffer));
1118		if (tail)
1119			memcpy(bufs + head, pipe->bufs, tail * sizeof(struct pipe_buffer));
1120	}
1121
1122	pipe->curbuf = 0;
1123	kfree(pipe->bufs);
1124	pipe->bufs = bufs;
1125	pipe->buffers = nr_pages;
1126	return nr_pages * PAGE_SIZE;
 
 
 
 
 
 
 
 
 
1127
1128out_revert_acct:
1129	(void) account_pipe_buffers(pipe->user, nr_pages, pipe->buffers);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1130	return ret;
1131}
1132
1133/*
1134 * After the inode slimming patch, i_pipe/i_bdev/i_cdev share the same
1135 * location, so checking ->i_pipe is not enough to verify that this is a
1136 * pipe.
1137 */
1138struct pipe_inode_info *get_pipe_info(struct file *file)
1139{
1140	return file->f_op == &pipefifo_fops ? file->private_data : NULL;
 
 
1141}
1142
1143long pipe_fcntl(struct file *file, unsigned int cmd, unsigned long arg)
1144{
1145	struct pipe_inode_info *pipe;
1146	long ret;
1147
1148	pipe = get_pipe_info(file);
1149	if (!pipe)
1150		return -EBADF;
1151
1152	__pipe_lock(pipe);
1153
1154	switch (cmd) {
1155	case F_SETPIPE_SZ:
1156		ret = pipe_set_size(pipe, arg);
 
 
 
 
 
 
 
 
 
 
 
 
 
1157		break;
 
1158	case F_GETPIPE_SZ:
1159		ret = pipe->buffers * PAGE_SIZE;
1160		break;
1161	default:
1162		ret = -EINVAL;
1163		break;
1164	}
1165
1166	__pipe_unlock(pipe);
 
1167	return ret;
1168}
1169
1170static const struct super_operations pipefs_ops = {
1171	.destroy_inode = free_inode_nonrcu,
1172	.statfs = simple_statfs,
1173};
1174
1175/*
1176 * pipefs should _never_ be mounted by userland - too much of security hassle,
1177 * no real gain from having the whole whorehouse mounted. So we don't need
1178 * any operations on the root directory. However, we need a non-trivial
1179 * d_name - pipe: will go nicely and kill the special-casing in procfs.
1180 */
1181static struct dentry *pipefs_mount(struct file_system_type *fs_type,
1182			 int flags, const char *dev_name, void *data)
1183{
1184	return mount_pseudo(fs_type, "pipe:", &pipefs_ops,
1185			&pipefs_dentry_operations, PIPEFS_MAGIC);
1186}
1187
1188static struct file_system_type pipe_fs_type = {
1189	.name		= "pipefs",
1190	.mount		= pipefs_mount,
1191	.kill_sb	= kill_anon_super,
1192};
1193
1194static int __init init_pipe_fs(void)
1195{
1196	int err = register_filesystem(&pipe_fs_type);
1197
1198	if (!err) {
1199		pipe_mnt = kern_mount(&pipe_fs_type);
1200		if (IS_ERR(pipe_mnt)) {
1201			err = PTR_ERR(pipe_mnt);
1202			unregister_filesystem(&pipe_fs_type);
1203		}
1204	}
1205	return err;
1206}
1207
 
 
 
 
 
 
1208fs_initcall(init_pipe_fs);
v3.1
 
   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 */
  31unsigned int pipe_max_size = 1048576;
  32
  33/*
  34 * Minimum pipe size, as required by POSIX
  35 */
  36unsigned 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
  53static 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
  59void 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}
  66EXPORT_SYMBOL(pipe_lock);
  67
  68void pipe_unlock(struct pipe_inode_info *pipe)
  69{
  70	if (pipe->inode)
  71		mutex_unlock(&pipe->inode->i_mutex);
  72}
  73EXPORT_SYMBOL(pipe_unlock);
  74
 
 
 
 
 
 
 
 
 
 
  75void 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 */
  90void 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
 105static int
 106pipe_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
 131static int
 132pipe_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 */
 161static 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 */
 183static 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
 198static 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 */
 228void *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}
 238EXPORT_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 */
 249void 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}
 258EXPORT_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 */
 272int 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}
 289EXPORT_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 */
 301void generic_pipe_buf_get(struct pipe_inode_info *pipe, struct pipe_buffer *buf)
 302{
 303	page_cache_get(buf->page);
 304}
 305EXPORT_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 */
 316int generic_pipe_buf_confirm(struct pipe_inode_info *info,
 317			     struct pipe_buffer *buf)
 318{
 319	return 0;
 320}
 321EXPORT_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 */
 331void generic_pipe_buf_release(struct pipe_inode_info *pipe,
 332			      struct pipe_buffer *buf)
 333{
 334	page_cache_release(buf->page);
 335}
 336EXPORT_SYMBOL(generic_pipe_buf_release);
 337
 338static 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
 348static ssize_t
 349pipe_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					ret = error;
 386				break;
 387			}
 388
 389			atomic = !iov_fault_in_pages_write(iov, chars);
 390redo:
 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_poll(&pipe->wait, POLLOUT | POLLWRNORM);
 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_poll(&pipe->wait, POLLOUT | POLLWRNORM);
 454		kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT);
 455	}
 456	if (ret > 0)
 457		file_accessed(filp);
 458	return ret;
 459}
 460
 
 
 
 
 
 461static ssize_t
 462pipe_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);
 508redo1:
 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);
 566redo2:
 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_poll(&pipe->wait, POLLIN | POLLRDNORM);
 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	}
 623out:
 624	mutex_unlock(&inode->i_mutex);
 625	if (do_wakeup) {
 626		wake_up_interruptible_sync_poll(&pipe->wait, POLLIN | POLLRDNORM);
 627		kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
 628	}
 629	if (ret > 0)
 630		file_update_time(filp);
 
 
 
 
 631	return ret;
 632}
 633
 634static ssize_t
 635bad_pipe_r(struct file *filp, char __user *buf, size_t count, loff_t *ppos)
 636{
 637	return -EBADF;
 638}
 639
 640static ssize_t
 641bad_pipe_w(struct file *filp, const char __user *buf, size_t count,
 642	   loff_t *ppos)
 643{
 644	return -EBADF;
 645}
 646
 647static 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 */
 673static unsigned int
 674pipe_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
 705static int
 706pipe_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_poll(&pipe->wait, POLLIN | POLLOUT | POLLRDNORM | POLLWRNORM | POLLERR | POLLHUP);
 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
 727static int
 728pipe_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
 741static int
 742pipe_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
 755static int
 756pipe_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
 774static int
 775pipe_read_release(struct inode *inode, struct file *filp)
 776{
 777	return pipe_release(inode, 1, 0);
 778}
 779
 780static int
 781pipe_write_release(struct inode *inode, struct file *filp)
 782{
 783	return pipe_release(inode, 0, 1);
 
 
 784}
 785
 786static int
 787pipe_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
 796static int
 797pipe_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
 813static int
 814pipe_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
 830static int
 831pipe_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 */
 856const 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
 868const 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
 880const 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
 893struct 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
 913void __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
 928void free_pipe_info(struct inode *inode)
 929{
 930	__free_pipe_info(inode->i_pipe);
 931	inode->i_pipe = NULL;
 932}
 933
 934static struct vfsmount *pipe_mnt __read_mostly;
 935
 936/*
 937 * pipefs_dname() is called from d_path().
 938 */
 939static 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
 945static const struct dentry_operations pipefs_dentry_operations = {
 946	.d_dname	= pipefs_dname,
 947};
 948
 949static struct inode * get_pipe_inode(void)
 950{
 951	struct inode *inode = new_inode_pseudo(pipe_mnt->mnt_sb);
 952	struct pipe_inode_info *pipe;
 953
 954	if (!inode)
 955		goto fail_inode;
 956
 957	inode->i_ino = get_next_ino();
 958
 959	pipe = alloc_pipe_info(inode);
 960	if (!pipe)
 961		goto fail_iput;
 
 962	inode->i_pipe = pipe;
 963
 964	pipe->readers = pipe->writers = 1;
 965	inode->i_fop = &rdwr_pipefifo_fops;
 966
 967	/*
 968	 * Mark the inode dirty from the very beginning,
 969	 * that way it will never be moved to the dirty
 970	 * list because "mark_inode_dirty()" will think
 971	 * that it already _is_ on the dirty list.
 972	 */
 973	inode->i_state = I_DIRTY;
 974	inode->i_mode = S_IFIFO | S_IRUSR | S_IWUSR;
 975	inode->i_uid = current_fsuid();
 976	inode->i_gid = current_fsgid();
 977	inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
 978
 979	return inode;
 980
 981fail_iput:
 982	iput(inode);
 983
 984fail_inode:
 985	return NULL;
 986}
 987
 988struct file *create_write_pipe(int flags)
 989{
 990	int err;
 991	struct inode *inode;
 992	struct file *f;
 993	struct path path;
 994	struct qstr name = { .name = "" };
 995
 996	err = -ENFILE;
 997	inode = get_pipe_inode();
 998	if (!inode)
 999		goto err;
1000
1001	err = -ENOMEM;
1002	path.dentry = d_alloc_pseudo(pipe_mnt->mnt_sb, &name);
1003	if (!path.dentry)
1004		goto err_inode;
1005	path.mnt = mntget(pipe_mnt);
1006
1007	d_instantiate(path.dentry, inode);
1008
1009	err = -ENFILE;
1010	f = alloc_file(&path, FMODE_WRITE, &write_pipefifo_fops);
1011	if (!f)
1012		goto err_dentry;
1013	f->f_mapping = inode->i_mapping;
1014
1015	f->f_flags = O_WRONLY | (flags & O_NONBLOCK);
1016	f->f_version = 0;
1017
1018	return f;
 
 
 
 
1019
1020 err_dentry:
1021	free_pipe_info(inode);
 
 
 
 
 
 
 
 
1022	path_put(&path);
1023	return ERR_PTR(err);
1024
1025 err_inode:
1026	free_pipe_info(inode);
1027	iput(inode);
1028 err:
1029	return ERR_PTR(err);
1030}
1031
1032void free_write_pipe(struct file *f)
1033{
1034	free_pipe_info(f->f_dentry->d_inode);
1035	path_put(&f->f_path);
1036	put_filp(f);
1037}
1038
1039struct file *create_read_pipe(struct file *wrf, int flags)
1040{
1041	/* Grab pipe from the writer */
1042	struct file *f = alloc_file(&wrf->f_path, FMODE_READ,
1043				    &read_pipefifo_fops);
1044	if (!f)
1045		return ERR_PTR(-ENFILE);
1046
1047	path_get(&wrf->f_path);
1048	f->f_flags = O_RDONLY | (flags & O_NONBLOCK);
1049
1050	return f;
1051}
1052
1053int do_pipe_flags(int *fd, int flags)
1054{
1055	struct file *fw, *fr;
1056	int error;
1057	int fdw, fdr;
1058
1059	if (flags & ~(O_CLOEXEC | O_NONBLOCK))
1060		return -EINVAL;
1061
1062	fw = create_write_pipe(flags);
1063	if (IS_ERR(fw))
1064		return PTR_ERR(fw);
1065	fr = create_read_pipe(fw, flags);
1066	error = PTR_ERR(fr);
1067	if (IS_ERR(fr))
1068		goto err_write_pipe;
1069
1070	error = get_unused_fd_flags(flags);
1071	if (error < 0)
1072		goto err_read_pipe;
1073	fdr = error;
1074
1075	error = get_unused_fd_flags(flags);
1076	if (error < 0)
1077		goto err_fdr;
1078	fdw = error;
1079
1080	audit_fd_pair(fdr, fdw);
1081	fd_install(fdr, fr);
1082	fd_install(fdw, fw);
1083	fd[0] = fdr;
1084	fd[1] = fdw;
1085
1086	return 0;
1087
1088 err_fdr:
1089	put_unused_fd(fdr);
1090 err_read_pipe:
1091	path_put(&fr->f_path);
1092	put_filp(fr);
1093 err_write_pipe:
1094	free_write_pipe(fw);
 
 
 
 
 
 
 
 
 
1095	return error;
1096}
1097
1098/*
1099 * sys_pipe() is the normal C calling standard for creating
1100 * a pipe. It's not the way Unix traditionally does this, though.
1101 */
1102SYSCALL_DEFINE2(pipe2, int __user *, fildes, int, flags)
1103{
 
1104	int fd[2];
1105	int error;
1106
1107	error = do_pipe_flags(fd, flags);
1108	if (!error) {
1109		if (copy_to_user(fildes, fd, sizeof(fd))) {
1110			sys_close(fd[0]);
1111			sys_close(fd[1]);
 
 
1112			error = -EFAULT;
 
 
 
1113		}
1114	}
1115	return error;
1116}
1117
 
 
 
 
 
1118SYSCALL_DEFINE1(pipe, int __user *, fildes)
1119{
1120	return sys_pipe2(fildes, 0);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1121}
1122
1123/*
1124 * Allocate a new array of pipe buffers and copy the info over. Returns the
1125 * pipe size if successful, or return -ERROR on error.
1126 */
1127static long pipe_set_size(struct pipe_inode_info *pipe, unsigned long nr_pages)
1128{
1129	struct pipe_buffer *bufs;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1130
1131	/*
1132	 * We can shrink the pipe, if arg >= pipe->nrbufs. Since we don't
1133	 * expect a lot of shrink+grow operations, just free and allocate
1134	 * again like we would do for growing. If the pipe currently
1135	 * contains more buffers than arg, then return busy.
1136	 */
1137	if (nr_pages < pipe->nrbufs)
1138		return -EBUSY;
 
 
1139
1140	bufs = kcalloc(nr_pages, sizeof(struct pipe_buffer), GFP_KERNEL);
1141	if (unlikely(!bufs))
1142		return -ENOMEM;
 
 
 
1143
1144	/*
1145	 * The pipe array wraps around, so just start the new one at zero
1146	 * and adjust the indexes.
1147	 */
1148	if (pipe->nrbufs) {
1149		unsigned int tail;
1150		unsigned int head;
1151
1152		tail = pipe->curbuf + pipe->nrbufs;
1153		if (tail < pipe->buffers)
1154			tail = 0;
1155		else
1156			tail &= (pipe->buffers - 1);
1157
1158		head = pipe->nrbufs - tail;
1159		if (head)
1160			memcpy(bufs, pipe->bufs + pipe->curbuf, head * sizeof(struct pipe_buffer));
1161		if (tail)
1162			memcpy(bufs + head, pipe->bufs, tail * sizeof(struct pipe_buffer));
1163	}
1164
1165	pipe->curbuf = 0;
1166	kfree(pipe->bufs);
1167	pipe->bufs = bufs;
1168	pipe->buffers = nr_pages;
1169	return nr_pages * PAGE_SIZE;
1170}
1171
1172/*
1173 * Currently we rely on the pipe array holding a power-of-2 number
1174 * of pages.
1175 */
1176static inline unsigned int round_pipe_size(unsigned int size)
1177{
1178	unsigned long nr_pages;
1179
1180	nr_pages = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
1181	return roundup_pow_of_two(nr_pages) << PAGE_SHIFT;
1182}
1183
1184/*
1185 * This should work even if CONFIG_PROC_FS isn't set, as proc_dointvec_minmax
1186 * will return an error.
1187 */
1188int pipe_proc_fn(struct ctl_table *table, int write, void __user *buf,
1189		 size_t *lenp, loff_t *ppos)
1190{
1191	int ret;
1192
1193	ret = proc_dointvec_minmax(table, write, buf, lenp, ppos);
1194	if (ret < 0 || !write)
1195		return ret;
1196
1197	pipe_max_size = round_pipe_size(pipe_max_size);
1198	return ret;
1199}
1200
1201/*
1202 * After the inode slimming patch, i_pipe/i_bdev/i_cdev share the same
1203 * location, so checking ->i_pipe is not enough to verify that this is a
1204 * pipe.
1205 */
1206struct pipe_inode_info *get_pipe_info(struct file *file)
1207{
1208	struct inode *i = file->f_path.dentry->d_inode;
1209
1210	return S_ISFIFO(i->i_mode) ? i->i_pipe : NULL;
1211}
1212
1213long pipe_fcntl(struct file *file, unsigned int cmd, unsigned long arg)
1214{
1215	struct pipe_inode_info *pipe;
1216	long ret;
1217
1218	pipe = get_pipe_info(file);
1219	if (!pipe)
1220		return -EBADF;
1221
1222	mutex_lock(&pipe->inode->i_mutex);
1223
1224	switch (cmd) {
1225	case F_SETPIPE_SZ: {
1226		unsigned int size, nr_pages;
1227
1228		size = round_pipe_size(arg);
1229		nr_pages = size >> PAGE_SHIFT;
1230
1231		ret = -EINVAL;
1232		if (!nr_pages)
1233			goto out;
1234
1235		if (!capable(CAP_SYS_RESOURCE) && size > pipe_max_size) {
1236			ret = -EPERM;
1237			goto out;
1238		}
1239		ret = pipe_set_size(pipe, nr_pages);
1240		break;
1241		}
1242	case F_GETPIPE_SZ:
1243		ret = pipe->buffers * PAGE_SIZE;
1244		break;
1245	default:
1246		ret = -EINVAL;
1247		break;
1248	}
1249
1250out:
1251	mutex_unlock(&pipe->inode->i_mutex);
1252	return ret;
1253}
1254
1255static const struct super_operations pipefs_ops = {
1256	.destroy_inode = free_inode_nonrcu,
 
1257};
1258
1259/*
1260 * pipefs should _never_ be mounted by userland - too much of security hassle,
1261 * no real gain from having the whole whorehouse mounted. So we don't need
1262 * any operations on the root directory. However, we need a non-trivial
1263 * d_name - pipe: will go nicely and kill the special-casing in procfs.
1264 */
1265static struct dentry *pipefs_mount(struct file_system_type *fs_type,
1266			 int flags, const char *dev_name, void *data)
1267{
1268	return mount_pseudo(fs_type, "pipe:", &pipefs_ops,
1269			&pipefs_dentry_operations, PIPEFS_MAGIC);
1270}
1271
1272static struct file_system_type pipe_fs_type = {
1273	.name		= "pipefs",
1274	.mount		= pipefs_mount,
1275	.kill_sb	= kill_anon_super,
1276};
1277
1278static int __init init_pipe_fs(void)
1279{
1280	int err = register_filesystem(&pipe_fs_type);
1281
1282	if (!err) {
1283		pipe_mnt = kern_mount(&pipe_fs_type);
1284		if (IS_ERR(pipe_mnt)) {
1285			err = PTR_ERR(pipe_mnt);
1286			unregister_filesystem(&pipe_fs_type);
1287		}
1288	}
1289	return err;
1290}
1291
1292static void __exit exit_pipe_fs(void)
1293{
1294	kern_unmount(pipe_mnt);
1295	unregister_filesystem(&pipe_fs_type);
1296}
1297
1298fs_initcall(init_pipe_fs);
1299module_exit(exit_pipe_fs);