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