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