| 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 | ret = error; |
| 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_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 | |
| 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_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 | } |
| 623 | out: |
| 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 | |
| 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_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 | |
| 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 | 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 | |
| 981 | fail_iput: |
| 982 | iput(inode); |
| 983 | |
| 984 | fail_inode: |
| 985 | return NULL; |
| 986 | } |
| 987 | |
| 988 | struct 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 | |
| 1032 | void 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 | |
| 1039 | struct 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 | |
| 1053 | int 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 | */ |
| 1102 | SYSCALL_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 | |
| 1118 | SYSCALL_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 | */ |
| 1127 | static 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 | */ |
| 1176 | static 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 | */ |
| 1188 | int 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 | */ |
| 1206 | struct 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 | |
| 1213 | long 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 | |
| 1250 | out: |
| 1251 | mutex_unlock(&pipe->inode->i_mutex); |
| 1252 | return ret; |
| 1253 | } |
| 1254 | |
| 1255 | static 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 | */ |
| 1265 | static 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 | |
| 1272 | static struct file_system_type pipe_fs_type = { |
| 1273 | .name = "pipefs", |
| 1274 | .mount = pipefs_mount, |
| 1275 | .kill_sb = kill_anon_super, |
| 1276 | }; |
| 1277 | |
| 1278 | static 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 | |
| 1292 | static void __exit exit_pipe_fs(void) |
| 1293 | { |
| 1294 | unregister_filesystem(&pipe_fs_type); |
| 1295 | mntput(pipe_mnt); |
| 1296 | } |
| 1297 | |
| 1298 | fs_initcall(init_pipe_fs); |
| 1299 | module_exit(exit_pipe_fs); |