1 /* 2 * POSIX message queues filesystem for Linux. 3 * 4 * Copyright (C) 2003,2004 Krzysztof Benedyczak (golbi@mat.uni.torun.pl) 5 * Michal Wronski (Michal.Wronski@motorola.com) 6 * 7 * Spinlocks: Mohamed Abbas (abbas.mohamed@intel.com) 8 * Lockless receive & send, fd based notify: 9 * Manfred Spraul (manfred@colorfullife.com) 10 * 11 * This file is released under the GPL. 12 */ 13 14 #include <linux/capability.h> 15 #include <linux/init.h> 16 #include <linux/pagemap.h> 17 #include <linux/file.h> 18 #include <linux/mount.h> 19 #include <linux/namei.h> 20 #include <linux/sysctl.h> 21 #include <linux/poll.h> 22 #include <linux/mqueue.h> 23 #include <linux/msg.h> 24 #include <linux/skbuff.h> 25 #include <linux/netlink.h> 26 #include <linux/syscalls.h> 27 #include <linux/signal.h> 28 #include <linux/mutex.h> 29 30 #include <net/sock.h> 31 #include "util.h" 32 33 #define MQUEUE_MAGIC 0x19800202 34 #define DIRENT_SIZE 20 35 #define FILENT_SIZE 80 36 37 #define SEND 0 38 #define RECV 1 39 40 #define STATE_NONE 0 41 #define STATE_PENDING 1 42 #define STATE_READY 2 43 44 /* used by sysctl */ 45 #define FS_MQUEUE 1 46 #define CTL_QUEUESMAX 2 47 #define CTL_MSGMAX 3 48 #define CTL_MSGSIZEMAX 4 49 50 /* default values */ 51 #define DFLT_QUEUESMAX 256 /* max number of message queues */ 52 #define DFLT_MSGMAX 10 /* max number of messages in each queue */ 53 #define HARD_MSGMAX (131072/sizeof(void*)) 54 #define DFLT_MSGSIZEMAX 8192 /* max message size */ 55 56 57 struct ext_wait_queue { /* queue of sleeping tasks */ 58 struct task_struct *task; 59 struct list_head list; 60 struct msg_msg *msg; /* ptr of loaded message */ 61 int state; /* one of STATE_* values */ 62 }; 63 64 struct mqueue_inode_info { 65 spinlock_t lock; 66 struct inode vfs_inode; 67 wait_queue_head_t wait_q; 68 69 struct msg_msg **messages; 70 struct mq_attr attr; 71 72 struct sigevent notify; 73 pid_t notify_owner; 74 struct user_struct *user; /* user who created, for accounting */ 75 struct sock *notify_sock; 76 struct sk_buff *notify_cookie; 77 78 /* for tasks waiting for free space and messages, respectively */ 79 struct ext_wait_queue e_wait_q[2]; 80 81 unsigned long qsize; /* size of queue in memory (sum of all msgs) */ 82 }; 83 84 static struct inode_operations mqueue_dir_inode_operations; 85 static struct file_operations mqueue_file_operations; 86 static struct super_operations mqueue_super_ops; 87 static void remove_notification(struct mqueue_inode_info *info); 88 89 static spinlock_t mq_lock; 90 static kmem_cache_t *mqueue_inode_cachep; 91 static struct vfsmount *mqueue_mnt; 92 93 static unsigned int queues_count; 94 static unsigned int queues_max = DFLT_QUEUESMAX; 95 static unsigned int msg_max = DFLT_MSGMAX; 96 static unsigned int msgsize_max = DFLT_MSGSIZEMAX; 97 98 static struct ctl_table_header * mq_sysctl_table; 99 100 static inline struct mqueue_inode_info *MQUEUE_I(struct inode *inode) 101 { 102 return container_of(inode, struct mqueue_inode_info, vfs_inode); 103 } 104 105 static struct inode *mqueue_get_inode(struct super_block *sb, int mode, 106 struct mq_attr *attr) 107 { 108 struct inode *inode; 109 110 inode = new_inode(sb); 111 if (inode) { 112 inode->i_mode = mode; 113 inode->i_uid = current->fsuid; 114 inode->i_gid = current->fsgid; 115 inode->i_blksize = PAGE_CACHE_SIZE; 116 inode->i_blocks = 0; 117 inode->i_mtime = inode->i_ctime = inode->i_atime = 118 CURRENT_TIME; 119 120 if (S_ISREG(mode)) { 121 struct mqueue_inode_info *info; 122 struct task_struct *p = current; 123 struct user_struct *u = p->user; 124 unsigned long mq_bytes, mq_msg_tblsz; 125 126 inode->i_fop = &mqueue_file_operations; 127 inode->i_size = FILENT_SIZE; 128 /* mqueue specific info */ 129 info = MQUEUE_I(inode); 130 spin_lock_init(&info->lock); 131 init_waitqueue_head(&info->wait_q); 132 INIT_LIST_HEAD(&info->e_wait_q[0].list); 133 INIT_LIST_HEAD(&info->e_wait_q[1].list); 134 info->messages = NULL; 135 info->notify_owner = 0; 136 info->qsize = 0; 137 info->user = NULL; /* set when all is ok */ 138 memset(&info->attr, 0, sizeof(info->attr)); 139 info->attr.mq_maxmsg = DFLT_MSGMAX; 140 info->attr.mq_msgsize = DFLT_MSGSIZEMAX; 141 if (attr) { 142 info->attr.mq_maxmsg = attr->mq_maxmsg; 143 info->attr.mq_msgsize = attr->mq_msgsize; 144 } 145 mq_msg_tblsz = info->attr.mq_maxmsg * sizeof(struct msg_msg *); 146 mq_bytes = (mq_msg_tblsz + 147 (info->attr.mq_maxmsg * info->attr.mq_msgsize)); 148 149 spin_lock(&mq_lock); 150 if (u->mq_bytes + mq_bytes < u->mq_bytes || 151 u->mq_bytes + mq_bytes > 152 p->signal->rlim[RLIMIT_MSGQUEUE].rlim_cur) { 153 spin_unlock(&mq_lock); 154 goto out_inode; 155 } 156 u->mq_bytes += mq_bytes; 157 spin_unlock(&mq_lock); 158 159 info->messages = kmalloc(mq_msg_tblsz, GFP_KERNEL); 160 if (!info->messages) { 161 spin_lock(&mq_lock); 162 u->mq_bytes -= mq_bytes; 163 spin_unlock(&mq_lock); 164 goto out_inode; 165 } 166 /* all is ok */ 167 info->user = get_uid(u); 168 } else if (S_ISDIR(mode)) { 169 inode->i_nlink++; 170 /* Some things misbehave if size == 0 on a directory */ 171 inode->i_size = 2 * DIRENT_SIZE; 172 inode->i_op = &mqueue_dir_inode_operations; 173 inode->i_fop = &simple_dir_operations; 174 } 175 } 176 return inode; 177 out_inode: 178 make_bad_inode(inode); 179 iput(inode); 180 return NULL; 181 } 182 183 static int mqueue_fill_super(struct super_block *sb, void *data, int silent) 184 { 185 struct inode *inode; 186 187 sb->s_blocksize = PAGE_CACHE_SIZE; 188 sb->s_blocksize_bits = PAGE_CACHE_SHIFT; 189 sb->s_magic = MQUEUE_MAGIC; 190 sb->s_op = &mqueue_super_ops; 191 192 inode = mqueue_get_inode(sb, S_IFDIR | S_ISVTX | S_IRWXUGO, NULL); 193 if (!inode) 194 return -ENOMEM; 195 196 sb->s_root = d_alloc_root(inode); 197 if (!sb->s_root) { 198 iput(inode); 199 return -ENOMEM; 200 } 201 202 return 0; 203 } 204 205 static struct super_block *mqueue_get_sb(struct file_system_type *fs_type, 206 int flags, const char *dev_name, 207 void *data) 208 { 209 return get_sb_single(fs_type, flags, data, mqueue_fill_super); 210 } 211 212 static void init_once(void *foo, kmem_cache_t * cachep, unsigned long flags) 213 { 214 struct mqueue_inode_info *p = (struct mqueue_inode_info *) foo; 215 216 if ((flags & (SLAB_CTOR_VERIFY | SLAB_CTOR_CONSTRUCTOR)) == 217 SLAB_CTOR_CONSTRUCTOR) 218 inode_init_once(&p->vfs_inode); 219 } 220 221 static struct inode *mqueue_alloc_inode(struct super_block *sb) 222 { 223 struct mqueue_inode_info *ei; 224 225 ei = kmem_cache_alloc(mqueue_inode_cachep, SLAB_KERNEL); 226 if (!ei) 227 return NULL; 228 return &ei->vfs_inode; 229 } 230 231 static void mqueue_destroy_inode(struct inode *inode) 232 { 233 kmem_cache_free(mqueue_inode_cachep, MQUEUE_I(inode)); 234 } 235 236 static void mqueue_delete_inode(struct inode *inode) 237 { 238 struct mqueue_inode_info *info; 239 struct user_struct *user; 240 unsigned long mq_bytes; 241 int i; 242 243 if (S_ISDIR(inode->i_mode)) { 244 clear_inode(inode); 245 return; 246 } 247 info = MQUEUE_I(inode); 248 spin_lock(&info->lock); 249 for (i = 0; i < info->attr.mq_curmsgs; i++) 250 free_msg(info->messages[i]); 251 kfree(info->messages); 252 spin_unlock(&info->lock); 253 254 clear_inode(inode); 255 256 mq_bytes = (info->attr.mq_maxmsg * sizeof(struct msg_msg *) + 257 (info->attr.mq_maxmsg * info->attr.mq_msgsize)); 258 user = info->user; 259 if (user) { 260 spin_lock(&mq_lock); 261 user->mq_bytes -= mq_bytes; 262 queues_count--; 263 spin_unlock(&mq_lock); 264 free_uid(user); 265 } 266 } 267 268 static int mqueue_create(struct inode *dir, struct dentry *dentry, 269 int mode, struct nameidata *nd) 270 { 271 struct inode *inode; 272 struct mq_attr *attr = dentry->d_fsdata; 273 int error; 274 275 spin_lock(&mq_lock); 276 if (queues_count >= queues_max && !capable(CAP_SYS_RESOURCE)) { 277 error = -ENOSPC; 278 goto out_lock; 279 } 280 queues_count++; 281 spin_unlock(&mq_lock); 282 283 inode = mqueue_get_inode(dir->i_sb, mode, attr); 284 if (!inode) { 285 error = -ENOMEM; 286 spin_lock(&mq_lock); 287 queues_count--; 288 goto out_lock; 289 } 290 291 dir->i_size += DIRENT_SIZE; 292 dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME; 293 294 d_instantiate(dentry, inode); 295 dget(dentry); 296 return 0; 297 out_lock: 298 spin_unlock(&mq_lock); 299 return error; 300 } 301 302 static int mqueue_unlink(struct inode *dir, struct dentry *dentry) 303 { 304 struct inode *inode = dentry->d_inode; 305 306 dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME; 307 dir->i_size -= DIRENT_SIZE; 308 inode->i_nlink--; 309 dput(dentry); 310 return 0; 311 } 312 313 /* 314 * This is routine for system read from queue file. 315 * To avoid mess with doing here some sort of mq_receive we allow 316 * to read only queue size & notification info (the only values 317 * that are interesting from user point of view and aren't accessible 318 * through std routines) 319 */ 320 static ssize_t mqueue_read_file(struct file *filp, char __user *u_data, 321 size_t count, loff_t * off) 322 { 323 struct mqueue_inode_info *info = MQUEUE_I(filp->f_dentry->d_inode); 324 char buffer[FILENT_SIZE]; 325 size_t slen; 326 loff_t o; 327 328 if (!count) 329 return 0; 330 331 spin_lock(&info->lock); 332 snprintf(buffer, sizeof(buffer), 333 "QSIZE:%-10lu NOTIFY:%-5d SIGNO:%-5d NOTIFY_PID:%-6d\n", 334 info->qsize, 335 info->notify_owner ? info->notify.sigev_notify : 0, 336 (info->notify_owner && 337 info->notify.sigev_notify == SIGEV_SIGNAL) ? 338 info->notify.sigev_signo : 0, 339 info->notify_owner); 340 spin_unlock(&info->lock); 341 buffer[sizeof(buffer)-1] = '\0'; 342 slen = strlen(buffer)+1; 343 344 o = *off; 345 if (o > slen) 346 return 0; 347 348 if (o + count > slen) 349 count = slen - o; 350 351 if (copy_to_user(u_data, buffer + o, count)) 352 return -EFAULT; 353 354 *off = o + count; 355 filp->f_dentry->d_inode->i_atime = filp->f_dentry->d_inode->i_ctime = CURRENT_TIME; 356 return count; 357 } 358 359 static int mqueue_flush_file(struct file *filp) 360 { 361 struct mqueue_inode_info *info = MQUEUE_I(filp->f_dentry->d_inode); 362 363 spin_lock(&info->lock); 364 if (current->tgid == info->notify_owner) 365 remove_notification(info); 366 367 spin_unlock(&info->lock); 368 return 0; 369 } 370 371 static unsigned int mqueue_poll_file(struct file *filp, struct poll_table_struct *poll_tab) 372 { 373 struct mqueue_inode_info *info = MQUEUE_I(filp->f_dentry->d_inode); 374 int retval = 0; 375 376 poll_wait(filp, &info->wait_q, poll_tab); 377 378 spin_lock(&info->lock); 379 if (info->attr.mq_curmsgs) 380 retval = POLLIN | POLLRDNORM; 381 382 if (info->attr.mq_curmsgs < info->attr.mq_maxmsg) 383 retval |= POLLOUT | POLLWRNORM; 384 spin_unlock(&info->lock); 385 386 return retval; 387 } 388 389 /* Adds current to info->e_wait_q[sr] before element with smaller prio */ 390 static void wq_add(struct mqueue_inode_info *info, int sr, 391 struct ext_wait_queue *ewp) 392 { 393 struct ext_wait_queue *walk; 394 395 ewp->task = current; 396 397 list_for_each_entry(walk, &info->e_wait_q[sr].list, list) { 398 if (walk->task->static_prio <= current->static_prio) { 399 list_add_tail(&ewp->list, &walk->list); 400 return; 401 } 402 } 403 list_add_tail(&ewp->list, &info->e_wait_q[sr].list); 404 } 405 406 /* 407 * Puts current task to sleep. Caller must hold queue lock. After return 408 * lock isn't held. 409 * sr: SEND or RECV 410 */ 411 static int wq_sleep(struct mqueue_inode_info *info, int sr, 412 long timeout, struct ext_wait_queue *ewp) 413 { 414 int retval; 415 signed long time; 416 417 wq_add(info, sr, ewp); 418 419 for (;;) { 420 set_current_state(TASK_INTERRUPTIBLE); 421 422 spin_unlock(&info->lock); 423 time = schedule_timeout(timeout); 424 425 while (ewp->state == STATE_PENDING) 426 cpu_relax(); 427 428 if (ewp->state == STATE_READY) { 429 retval = 0; 430 goto out; 431 } 432 spin_lock(&info->lock); 433 if (ewp->state == STATE_READY) { 434 retval = 0; 435 goto out_unlock; 436 } 437 if (signal_pending(current)) { 438 retval = -ERESTARTSYS; 439 break; 440 } 441 if (time == 0) { 442 retval = -ETIMEDOUT; 443 break; 444 } 445 } 446 list_del(&ewp->list); 447 out_unlock: 448 spin_unlock(&info->lock); 449 out: 450 return retval; 451 } 452 453 /* 454 * Returns waiting task that should be serviced first or NULL if none exists 455 */ 456 static struct ext_wait_queue *wq_get_first_waiter( 457 struct mqueue_inode_info *info, int sr) 458 { 459 struct list_head *ptr; 460 461 ptr = info->e_wait_q[sr].list.prev; 462 if (ptr == &info->e_wait_q[sr].list) 463 return NULL; 464 return list_entry(ptr, struct ext_wait_queue, list); 465 } 466 467 /* Auxiliary functions to manipulate messages' list */ 468 static void msg_insert(struct msg_msg *ptr, struct mqueue_inode_info *info) 469 { 470 int k; 471 472 k = info->attr.mq_curmsgs - 1; 473 while (k >= 0 && info->messages[k]->m_type >= ptr->m_type) { 474 info->messages[k + 1] = info->messages[k]; 475 k--; 476 } 477 info->attr.mq_curmsgs++; 478 info->qsize += ptr->m_ts; 479 info->messages[k + 1] = ptr; 480 } 481 482 static inline struct msg_msg *msg_get(struct mqueue_inode_info *info) 483 { 484 info->qsize -= info->messages[--info->attr.mq_curmsgs]->m_ts; 485 return info->messages[info->attr.mq_curmsgs]; 486 } 487 488 static inline void set_cookie(struct sk_buff *skb, char code) 489 { 490 ((char*)skb->data)[NOTIFY_COOKIE_LEN-1] = code; 491 } 492 493 /* 494 * The next function is only to split too long sys_mq_timedsend 495 */ 496 static void __do_notify(struct mqueue_inode_info *info) 497 { 498 /* notification 499 * invoked when there is registered process and there isn't process 500 * waiting synchronously for message AND state of queue changed from 501 * empty to not empty. Here we are sure that no one is waiting 502 * synchronously. */ 503 if (info->notify_owner && 504 info->attr.mq_curmsgs == 1) { 505 struct siginfo sig_i; 506 switch (info->notify.sigev_notify) { 507 case SIGEV_NONE: 508 break; 509 case SIGEV_SIGNAL: 510 /* sends signal */ 511 512 sig_i.si_signo = info->notify.sigev_signo; 513 sig_i.si_errno = 0; 514 sig_i.si_code = SI_MESGQ; 515 sig_i.si_value = info->notify.sigev_value; 516 sig_i.si_pid = current->tgid; 517 sig_i.si_uid = current->uid; 518 519 kill_proc_info(info->notify.sigev_signo, 520 &sig_i, info->notify_owner); 521 break; 522 case SIGEV_THREAD: 523 set_cookie(info->notify_cookie, NOTIFY_WOKENUP); 524 netlink_sendskb(info->notify_sock, 525 info->notify_cookie, 0); 526 break; 527 } 528 /* after notification unregisters process */ 529 info->notify_owner = 0; 530 } 531 wake_up(&info->wait_q); 532 } 533 534 static long prepare_timeout(const struct timespec __user *u_arg) 535 { 536 struct timespec ts, nowts; 537 long timeout; 538 539 if (u_arg) { 540 if (unlikely(copy_from_user(&ts, u_arg, 541 sizeof(struct timespec)))) 542 return -EFAULT; 543 544 if (unlikely(ts.tv_nsec < 0 || ts.tv_sec < 0 545 || ts.tv_nsec >= NSEC_PER_SEC)) 546 return -EINVAL; 547 nowts = CURRENT_TIME; 548 /* first subtract as jiffies can't be too big */ 549 ts.tv_sec -= nowts.tv_sec; 550 if (ts.tv_nsec < nowts.tv_nsec) { 551 ts.tv_nsec += NSEC_PER_SEC; 552 ts.tv_sec--; 553 } 554 ts.tv_nsec -= nowts.tv_nsec; 555 if (ts.tv_sec < 0) 556 return 0; 557 558 timeout = timespec_to_jiffies(&ts) + 1; 559 } else 560 return MAX_SCHEDULE_TIMEOUT; 561 562 return timeout; 563 } 564 565 static void remove_notification(struct mqueue_inode_info *info) 566 { 567 if (info->notify_owner != 0 && 568 info->notify.sigev_notify == SIGEV_THREAD) { 569 set_cookie(info->notify_cookie, NOTIFY_REMOVED); 570 netlink_sendskb(info->notify_sock, info->notify_cookie, 0); 571 } 572 info->notify_owner = 0; 573 } 574 575 static int mq_attr_ok(struct mq_attr *attr) 576 { 577 if (attr->mq_maxmsg <= 0 || attr->mq_msgsize <= 0) 578 return 0; 579 if (capable(CAP_SYS_RESOURCE)) { 580 if (attr->mq_maxmsg > HARD_MSGMAX) 581 return 0; 582 } else { 583 if (attr->mq_maxmsg > msg_max || 584 attr->mq_msgsize > msgsize_max) 585 return 0; 586 } 587 /* check for overflow */ 588 if (attr->mq_msgsize > ULONG_MAX/attr->mq_maxmsg) 589 return 0; 590 if ((unsigned long)(attr->mq_maxmsg * attr->mq_msgsize) + 591 (attr->mq_maxmsg * sizeof (struct msg_msg *)) < 592 (unsigned long)(attr->mq_maxmsg * attr->mq_msgsize)) 593 return 0; 594 return 1; 595 } 596 597 /* 598 * Invoked when creating a new queue via sys_mq_open 599 */ 600 static struct file *do_create(struct dentry *dir, struct dentry *dentry, 601 int oflag, mode_t mode, struct mq_attr __user *u_attr) 602 { 603 struct mq_attr attr; 604 int ret; 605 606 if (u_attr) { 607 ret = -EFAULT; 608 if (copy_from_user(&attr, u_attr, sizeof(attr))) 609 goto out; 610 ret = -EINVAL; 611 if (!mq_attr_ok(&attr)) 612 goto out; 613 /* store for use during create */ 614 dentry->d_fsdata = &attr; 615 } 616 617 mode &= ~current->fs->umask; 618 ret = vfs_create(dir->d_inode, dentry, mode, NULL); 619 dentry->d_fsdata = NULL; 620 if (ret) 621 goto out; 622 623 return dentry_open(dentry, mqueue_mnt, oflag); 624 625 out: 626 dput(dentry); 627 mntput(mqueue_mnt); 628 return ERR_PTR(ret); 629 } 630 631 /* Opens existing queue */ 632 static struct file *do_open(struct dentry *dentry, int oflag) 633 { 634 static int oflag2acc[O_ACCMODE] = { MAY_READ, MAY_WRITE, 635 MAY_READ | MAY_WRITE }; 636 637 if ((oflag & O_ACCMODE) == (O_RDWR | O_WRONLY)) { 638 dput(dentry); 639 mntput(mqueue_mnt); 640 return ERR_PTR(-EINVAL); 641 } 642 643 if (permission(dentry->d_inode, oflag2acc[oflag & O_ACCMODE], NULL)) { 644 dput(dentry); 645 mntput(mqueue_mnt); 646 return ERR_PTR(-EACCES); 647 } 648 649 return dentry_open(dentry, mqueue_mnt, oflag); 650 } 651 652 asmlinkage long sys_mq_open(const char __user *u_name, int oflag, mode_t mode, 653 struct mq_attr __user *u_attr) 654 { 655 struct dentry *dentry; 656 struct file *filp; 657 char *name; 658 int fd, error; 659 660 if (IS_ERR(name = getname(u_name))) 661 return PTR_ERR(name); 662 663 fd = get_unused_fd(); 664 if (fd < 0) 665 goto out_putname; 666 667 mutex_lock(&mqueue_mnt->mnt_root->d_inode->i_mutex); 668 dentry = lookup_one_len(name, mqueue_mnt->mnt_root, strlen(name)); 669 if (IS_ERR(dentry)) { 670 error = PTR_ERR(dentry); 671 goto out_err; 672 } 673 mntget(mqueue_mnt); 674 675 if (oflag & O_CREAT) { 676 if (dentry->d_inode) { /* entry already exists */ 677 error = -EEXIST; 678 if (oflag & O_EXCL) 679 goto out; 680 filp = do_open(dentry, oflag); 681 } else { 682 filp = do_create(mqueue_mnt->mnt_root, dentry, 683 oflag, mode, u_attr); 684 } 685 } else { 686 error = -ENOENT; 687 if (!dentry->d_inode) 688 goto out; 689 filp = do_open(dentry, oflag); 690 } 691 692 if (IS_ERR(filp)) { 693 error = PTR_ERR(filp); 694 goto out_putfd; 695 } 696 697 set_close_on_exec(fd, 1); 698 fd_install(fd, filp); 699 goto out_upsem; 700 701 out: 702 dput(dentry); 703 mntput(mqueue_mnt); 704 out_putfd: 705 put_unused_fd(fd); 706 out_err: 707 fd = error; 708 out_upsem: 709 mutex_unlock(&mqueue_mnt->mnt_root->d_inode->i_mutex); 710 out_putname: 711 putname(name); 712 return fd; 713 } 714 715 asmlinkage long sys_mq_unlink(const char __user *u_name) 716 { 717 int err; 718 char *name; 719 struct dentry *dentry; 720 struct inode *inode = NULL; 721 722 name = getname(u_name); 723 if (IS_ERR(name)) 724 return PTR_ERR(name); 725 726 mutex_lock(&mqueue_mnt->mnt_root->d_inode->i_mutex); 727 dentry = lookup_one_len(name, mqueue_mnt->mnt_root, strlen(name)); 728 if (IS_ERR(dentry)) { 729 err = PTR_ERR(dentry); 730 goto out_unlock; 731 } 732 733 if (!dentry->d_inode) { 734 err = -ENOENT; 735 goto out_err; 736 } 737 738 inode = dentry->d_inode; 739 if (inode) 740 atomic_inc(&inode->i_count); 741 742 err = vfs_unlink(dentry->d_parent->d_inode, dentry); 743 out_err: 744 dput(dentry); 745 746 out_unlock: 747 mutex_unlock(&mqueue_mnt->mnt_root->d_inode->i_mutex); 748 putname(name); 749 if (inode) 750 iput(inode); 751 752 return err; 753 } 754 755 /* Pipelined send and receive functions. 756 * 757 * If a receiver finds no waiting message, then it registers itself in the 758 * list of waiting receivers. A sender checks that list before adding the new 759 * message into the message array. If there is a waiting receiver, then it 760 * bypasses the message array and directly hands the message over to the 761 * receiver. 762 * The receiver accepts the message and returns without grabbing the queue 763 * spinlock. Therefore an intermediate STATE_PENDING state and memory barriers 764 * are necessary. The same algorithm is used for sysv semaphores, see 765 * ipc/sem.c for more details. 766 * 767 * The same algorithm is used for senders. 768 */ 769 770 /* pipelined_send() - send a message directly to the task waiting in 771 * sys_mq_timedreceive() (without inserting message into a queue). 772 */ 773 static inline void pipelined_send(struct mqueue_inode_info *info, 774 struct msg_msg *message, 775 struct ext_wait_queue *receiver) 776 { 777 receiver->msg = message; 778 list_del(&receiver->list); 779 receiver->state = STATE_PENDING; 780 wake_up_process(receiver->task); 781 smp_wmb(); 782 receiver->state = STATE_READY; 783 } 784 785 /* pipelined_receive() - if there is task waiting in sys_mq_timedsend() 786 * gets its message and put to the queue (we have one free place for sure). */ 787 static inline void pipelined_receive(struct mqueue_inode_info *info) 788 { 789 struct ext_wait_queue *sender = wq_get_first_waiter(info, SEND); 790 791 if (!sender) { 792 /* for poll */ 793 wake_up_interruptible(&info->wait_q); 794 return; 795 } 796 msg_insert(sender->msg, info); 797 list_del(&sender->list); 798 sender->state = STATE_PENDING; 799 wake_up_process(sender->task); 800 smp_wmb(); 801 sender->state = STATE_READY; 802 } 803 804 asmlinkage long sys_mq_timedsend(mqd_t mqdes, const char __user *u_msg_ptr, 805 size_t msg_len, unsigned int msg_prio, 806 const struct timespec __user *u_abs_timeout) 807 { 808 struct file *filp; 809 struct inode *inode; 810 struct ext_wait_queue wait; 811 struct ext_wait_queue *receiver; 812 struct msg_msg *msg_ptr; 813 struct mqueue_inode_info *info; 814 long timeout; 815 int ret; 816 817 if (unlikely(msg_prio >= (unsigned long) MQ_PRIO_MAX)) 818 return -EINVAL; 819 820 timeout = prepare_timeout(u_abs_timeout); 821 822 ret = -EBADF; 823 filp = fget(mqdes); 824 if (unlikely(!filp)) 825 goto out; 826 827 inode = filp->f_dentry->d_inode; 828 if (unlikely(filp->f_op != &mqueue_file_operations)) 829 goto out_fput; 830 info = MQUEUE_I(inode); 831 832 if (unlikely(!(filp->f_mode & FMODE_WRITE))) 833 goto out_fput; 834 835 if (unlikely(msg_len > info->attr.mq_msgsize)) { 836 ret = -EMSGSIZE; 837 goto out_fput; 838 } 839 840 /* First try to allocate memory, before doing anything with 841 * existing queues. */ 842 msg_ptr = load_msg(u_msg_ptr, msg_len); 843 if (IS_ERR(msg_ptr)) { 844 ret = PTR_ERR(msg_ptr); 845 goto out_fput; 846 } 847 msg_ptr->m_ts = msg_len; 848 msg_ptr->m_type = msg_prio; 849 850 spin_lock(&info->lock); 851 852 if (info->attr.mq_curmsgs == info->attr.mq_maxmsg) { 853 if (filp->f_flags & O_NONBLOCK) { 854 spin_unlock(&info->lock); 855 ret = -EAGAIN; 856 } else if (unlikely(timeout < 0)) { 857 spin_unlock(&info->lock); 858 ret = timeout; 859 } else { 860 wait.task = current; 861 wait.msg = (void *) msg_ptr; 862 wait.state = STATE_NONE; 863 ret = wq_sleep(info, SEND, timeout, &wait); 864 } 865 if (ret < 0) 866 free_msg(msg_ptr); 867 } else { 868 receiver = wq_get_first_waiter(info, RECV); 869 if (receiver) { 870 pipelined_send(info, msg_ptr, receiver); 871 } else { 872 /* adds message to the queue */ 873 msg_insert(msg_ptr, info); 874 __do_notify(info); 875 } 876 inode->i_atime = inode->i_mtime = inode->i_ctime = 877 CURRENT_TIME; 878 spin_unlock(&info->lock); 879 ret = 0; 880 } 881 out_fput: 882 fput(filp); 883 out: 884 return ret; 885 } 886 887 asmlinkage ssize_t sys_mq_timedreceive(mqd_t mqdes, char __user *u_msg_ptr, 888 size_t msg_len, unsigned int __user *u_msg_prio, 889 const struct timespec __user *u_abs_timeout) 890 { 891 long timeout; 892 ssize_t ret; 893 struct msg_msg *msg_ptr; 894 struct file *filp; 895 struct inode *inode; 896 struct mqueue_inode_info *info; 897 struct ext_wait_queue wait; 898 899 timeout = prepare_timeout(u_abs_timeout); 900 901 ret = -EBADF; 902 filp = fget(mqdes); 903 if (unlikely(!filp)) 904 goto out; 905 906 inode = filp->f_dentry->d_inode; 907 if (unlikely(filp->f_op != &mqueue_file_operations)) 908 goto out_fput; 909 info = MQUEUE_I(inode); 910 911 if (unlikely(!(filp->f_mode & FMODE_READ))) 912 goto out_fput; 913 914 /* checks if buffer is big enough */ 915 if (unlikely(msg_len < info->attr.mq_msgsize)) { 916 ret = -EMSGSIZE; 917 goto out_fput; 918 } 919 920 spin_lock(&info->lock); 921 if (info->attr.mq_curmsgs == 0) { 922 if (filp->f_flags & O_NONBLOCK) { 923 spin_unlock(&info->lock); 924 ret = -EAGAIN; 925 msg_ptr = NULL; 926 } else if (unlikely(timeout < 0)) { 927 spin_unlock(&info->lock); 928 ret = timeout; 929 msg_ptr = NULL; 930 } else { 931 wait.task = current; 932 wait.state = STATE_NONE; 933 ret = wq_sleep(info, RECV, timeout, &wait); 934 msg_ptr = wait.msg; 935 } 936 } else { 937 msg_ptr = msg_get(info); 938 939 inode->i_atime = inode->i_mtime = inode->i_ctime = 940 CURRENT_TIME; 941 942 /* There is now free space in queue. */ 943 pipelined_receive(info); 944 spin_unlock(&info->lock); 945 ret = 0; 946 } 947 if (ret == 0) { 948 ret = msg_ptr->m_ts; 949 950 if ((u_msg_prio && put_user(msg_ptr->m_type, u_msg_prio)) || 951 store_msg(u_msg_ptr, msg_ptr, msg_ptr->m_ts)) { 952 ret = -EFAULT; 953 } 954 free_msg(msg_ptr); 955 } 956 out_fput: 957 fput(filp); 958 out: 959 return ret; 960 } 961 962 /* 963 * Notes: the case when user wants us to deregister (with NULL as pointer) 964 * and he isn't currently owner of notification, will be silently discarded. 965 * It isn't explicitly defined in the POSIX. 966 */ 967 asmlinkage long sys_mq_notify(mqd_t mqdes, 968 const struct sigevent __user *u_notification) 969 { 970 int ret; 971 struct file *filp; 972 struct sock *sock; 973 struct inode *inode; 974 struct sigevent notification; 975 struct mqueue_inode_info *info; 976 struct sk_buff *nc; 977 978 nc = NULL; 979 sock = NULL; 980 if (u_notification != NULL) { 981 if (copy_from_user(¬ification, u_notification, 982 sizeof(struct sigevent))) 983 return -EFAULT; 984 985 if (unlikely(notification.sigev_notify != SIGEV_NONE && 986 notification.sigev_notify != SIGEV_SIGNAL && 987 notification.sigev_notify != SIGEV_THREAD)) 988 return -EINVAL; 989 if (notification.sigev_notify == SIGEV_SIGNAL && 990 !valid_signal(notification.sigev_signo)) { 991 return -EINVAL; 992 } 993 if (notification.sigev_notify == SIGEV_THREAD) { 994 /* create the notify skb */ 995 nc = alloc_skb(NOTIFY_COOKIE_LEN, GFP_KERNEL); 996 ret = -ENOMEM; 997 if (!nc) 998 goto out; 999 ret = -EFAULT; 1000 if (copy_from_user(nc->data, 1001 notification.sigev_value.sival_ptr, 1002 NOTIFY_COOKIE_LEN)) { 1003 goto out; 1004 } 1005 1006 /* TODO: add a header? */ 1007 skb_put(nc, NOTIFY_COOKIE_LEN); 1008 /* and attach it to the socket */ 1009 retry: 1010 filp = fget(notification.sigev_signo); 1011 ret = -EBADF; 1012 if (!filp) 1013 goto out; 1014 sock = netlink_getsockbyfilp(filp); 1015 fput(filp); 1016 if (IS_ERR(sock)) { 1017 ret = PTR_ERR(sock); 1018 sock = NULL; 1019 goto out; 1020 } 1021 1022 ret = netlink_attachskb(sock, nc, 0, 1023 MAX_SCHEDULE_TIMEOUT, NULL); 1024 if (ret == 1) 1025 goto retry; 1026 if (ret) { 1027 sock = NULL; 1028 nc = NULL; 1029 goto out; 1030 } 1031 } 1032 } 1033 1034 ret = -EBADF; 1035 filp = fget(mqdes); 1036 if (!filp) 1037 goto out; 1038 1039 inode = filp->f_dentry->d_inode; 1040 if (unlikely(filp->f_op != &mqueue_file_operations)) 1041 goto out_fput; 1042 info = MQUEUE_I(inode); 1043 1044 ret = 0; 1045 spin_lock(&info->lock); 1046 if (u_notification == NULL) { 1047 if (info->notify_owner == current->tgid) { 1048 remove_notification(info); 1049 inode->i_atime = inode->i_ctime = CURRENT_TIME; 1050 } 1051 } else if (info->notify_owner != 0) { 1052 ret = -EBUSY; 1053 } else { 1054 switch (notification.sigev_notify) { 1055 case SIGEV_NONE: 1056 info->notify.sigev_notify = SIGEV_NONE; 1057 break; 1058 case SIGEV_THREAD: 1059 info->notify_sock = sock; 1060 info->notify_cookie = nc; 1061 sock = NULL; 1062 nc = NULL; 1063 info->notify.sigev_notify = SIGEV_THREAD; 1064 break; 1065 case SIGEV_SIGNAL: 1066 info->notify.sigev_signo = notification.sigev_signo; 1067 info->notify.sigev_value = notification.sigev_value; 1068 info->notify.sigev_notify = SIGEV_SIGNAL; 1069 break; 1070 } 1071 info->notify_owner = current->tgid; 1072 inode->i_atime = inode->i_ctime = CURRENT_TIME; 1073 } 1074 spin_unlock(&info->lock); 1075 out_fput: 1076 fput(filp); 1077 out: 1078 if (sock) { 1079 netlink_detachskb(sock, nc); 1080 } else if (nc) { 1081 dev_kfree_skb(nc); 1082 } 1083 return ret; 1084 } 1085 1086 asmlinkage long sys_mq_getsetattr(mqd_t mqdes, 1087 const struct mq_attr __user *u_mqstat, 1088 struct mq_attr __user *u_omqstat) 1089 { 1090 int ret; 1091 struct mq_attr mqstat, omqstat; 1092 struct file *filp; 1093 struct inode *inode; 1094 struct mqueue_inode_info *info; 1095 1096 if (u_mqstat != NULL) { 1097 if (copy_from_user(&mqstat, u_mqstat, sizeof(struct mq_attr))) 1098 return -EFAULT; 1099 if (mqstat.mq_flags & (~O_NONBLOCK)) 1100 return -EINVAL; 1101 } 1102 1103 ret = -EBADF; 1104 filp = fget(mqdes); 1105 if (!filp) 1106 goto out; 1107 1108 inode = filp->f_dentry->d_inode; 1109 if (unlikely(filp->f_op != &mqueue_file_operations)) 1110 goto out_fput; 1111 info = MQUEUE_I(inode); 1112 1113 spin_lock(&info->lock); 1114 1115 omqstat = info->attr; 1116 omqstat.mq_flags = filp->f_flags & O_NONBLOCK; 1117 if (u_mqstat) { 1118 if (mqstat.mq_flags & O_NONBLOCK) 1119 filp->f_flags |= O_NONBLOCK; 1120 else 1121 filp->f_flags &= ~O_NONBLOCK; 1122 1123 inode->i_atime = inode->i_ctime = CURRENT_TIME; 1124 } 1125 1126 spin_unlock(&info->lock); 1127 1128 ret = 0; 1129 if (u_omqstat != NULL && copy_to_user(u_omqstat, &omqstat, 1130 sizeof(struct mq_attr))) 1131 ret = -EFAULT; 1132 1133 out_fput: 1134 fput(filp); 1135 out: 1136 return ret; 1137 } 1138 1139 static struct inode_operations mqueue_dir_inode_operations = { 1140 .lookup = simple_lookup, 1141 .create = mqueue_create, 1142 .unlink = mqueue_unlink, 1143 }; 1144 1145 static struct file_operations mqueue_file_operations = { 1146 .flush = mqueue_flush_file, 1147 .poll = mqueue_poll_file, 1148 .read = mqueue_read_file, 1149 }; 1150 1151 static struct super_operations mqueue_super_ops = { 1152 .alloc_inode = mqueue_alloc_inode, 1153 .destroy_inode = mqueue_destroy_inode, 1154 .statfs = simple_statfs, 1155 .delete_inode = mqueue_delete_inode, 1156 .drop_inode = generic_delete_inode, 1157 }; 1158 1159 static struct file_system_type mqueue_fs_type = { 1160 .name = "mqueue", 1161 .get_sb = mqueue_get_sb, 1162 .kill_sb = kill_litter_super, 1163 }; 1164 1165 static int msg_max_limit_min = DFLT_MSGMAX; 1166 static int msg_max_limit_max = HARD_MSGMAX; 1167 1168 static int msg_maxsize_limit_min = DFLT_MSGSIZEMAX; 1169 static int msg_maxsize_limit_max = INT_MAX; 1170 1171 static ctl_table mq_sysctls[] = { 1172 { 1173 .ctl_name = CTL_QUEUESMAX, 1174 .procname = "queues_max", 1175 .data = &queues_max, 1176 .maxlen = sizeof(int), 1177 .mode = 0644, 1178 .proc_handler = &proc_dointvec, 1179 }, 1180 { 1181 .ctl_name = CTL_MSGMAX, 1182 .procname = "msg_max", 1183 .data = &msg_max, 1184 .maxlen = sizeof(int), 1185 .mode = 0644, 1186 .proc_handler = &proc_dointvec_minmax, 1187 .extra1 = &msg_max_limit_min, 1188 .extra2 = &msg_max_limit_max, 1189 }, 1190 { 1191 .ctl_name = CTL_MSGSIZEMAX, 1192 .procname = "msgsize_max", 1193 .data = &msgsize_max, 1194 .maxlen = sizeof(int), 1195 .mode = 0644, 1196 .proc_handler = &proc_dointvec_minmax, 1197 .extra1 = &msg_maxsize_limit_min, 1198 .extra2 = &msg_maxsize_limit_max, 1199 }, 1200 { .ctl_name = 0 } 1201 }; 1202 1203 static ctl_table mq_sysctl_dir[] = { 1204 { 1205 .ctl_name = FS_MQUEUE, 1206 .procname = "mqueue", 1207 .mode = 0555, 1208 .child = mq_sysctls, 1209 }, 1210 { .ctl_name = 0 } 1211 }; 1212 1213 static ctl_table mq_sysctl_root[] = { 1214 { 1215 .ctl_name = CTL_FS, 1216 .procname = "fs", 1217 .mode = 0555, 1218 .child = mq_sysctl_dir, 1219 }, 1220 { .ctl_name = 0 } 1221 }; 1222 1223 static int __init init_mqueue_fs(void) 1224 { 1225 int error; 1226 1227 mqueue_inode_cachep = kmem_cache_create("mqueue_inode_cache", 1228 sizeof(struct mqueue_inode_info), 0, 1229 SLAB_HWCACHE_ALIGN, init_once, NULL); 1230 if (mqueue_inode_cachep == NULL) 1231 return -ENOMEM; 1232 1233 /* ignore failues - they are not fatal */ 1234 mq_sysctl_table = register_sysctl_table(mq_sysctl_root, 0); 1235 1236 error = register_filesystem(&mqueue_fs_type); 1237 if (error) 1238 goto out_sysctl; 1239 1240 if (IS_ERR(mqueue_mnt = kern_mount(&mqueue_fs_type))) { 1241 error = PTR_ERR(mqueue_mnt); 1242 goto out_filesystem; 1243 } 1244 1245 /* internal initialization - not common for vfs */ 1246 queues_count = 0; 1247 spin_lock_init(&mq_lock); 1248 1249 return 0; 1250 1251 out_filesystem: 1252 unregister_filesystem(&mqueue_fs_type); 1253 out_sysctl: 1254 if (mq_sysctl_table) 1255 unregister_sysctl_table(mq_sysctl_table); 1256 if (kmem_cache_destroy(mqueue_inode_cachep)) { 1257 printk(KERN_INFO 1258 "mqueue_inode_cache: not all structures were freed\n"); 1259 } 1260 return error; 1261 } 1262 1263 __initcall(init_mqueue_fs); 1264