1 /* 2 * POSIX message queues filesystem for Linux. 3 * 4 * Copyright (C) 2003,2004 Krzysztof Benedyczak (golbi@mat.uni.torun.pl) 5 * Michal Wronski (wrona@mat.uni.torun.pl) 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/init.h> 15 #include <linux/pagemap.h> 16 #include <linux/file.h> 17 #include <linux/mount.h> 18 #include <linux/namei.h> 19 #include <linux/sysctl.h> 20 #include <linux/poll.h> 21 #include <linux/mqueue.h> 22 #include <linux/msg.h> 23 #include <linux/skbuff.h> 24 #include <linux/netlink.h> 25 #include <linux/syscalls.h> 26 #include <linux/signal.h> 27 #include <net/sock.h> 28 #include "util.h" 29 30 #define MQUEUE_MAGIC 0x19800202 31 #define DIRENT_SIZE 20 32 #define FILENT_SIZE 80 33 34 #define SEND 0 35 #define RECV 1 36 37 #define STATE_NONE 0 38 #define STATE_PENDING 1 39 #define STATE_READY 2 40 41 /* used by sysctl */ 42 #define FS_MQUEUE 1 43 #define CTL_QUEUESMAX 2 44 #define CTL_MSGMAX 3 45 #define CTL_MSGSIZEMAX 4 46 47 /* default values */ 48 #define DFLT_QUEUESMAX 256 /* max number of message queues */ 49 #define DFLT_MSGMAX 10 /* max number of messages in each queue */ 50 #define HARD_MSGMAX (131072/sizeof(void*)) 51 #define DFLT_MSGSIZEMAX 8192 /* max message size */ 52 53 #define NOTIFY_COOKIE_LEN 32 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 accouting */ 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 file *filp; 602 struct mq_attr attr; 603 int ret; 604 605 if (u_attr != NULL) { 606 if (copy_from_user(&attr, u_attr, sizeof(attr))) 607 return ERR_PTR(-EFAULT); 608 if (!mq_attr_ok(&attr)) 609 return ERR_PTR(-EINVAL); 610 /* store for use during create */ 611 dentry->d_fsdata = &attr; 612 } 613 614 ret = vfs_create(dir->d_inode, dentry, mode, NULL); 615 dentry->d_fsdata = NULL; 616 if (ret) 617 return ERR_PTR(ret); 618 619 filp = dentry_open(dentry, mqueue_mnt, oflag); 620 if (!IS_ERR(filp)) 621 dget(dentry); 622 623 return filp; 624 } 625 626 /* Opens existing queue */ 627 static struct file *do_open(struct dentry *dentry, int oflag) 628 { 629 static int oflag2acc[O_ACCMODE] = { MAY_READ, MAY_WRITE, 630 MAY_READ | MAY_WRITE }; 631 struct file *filp; 632 633 if ((oflag & O_ACCMODE) == (O_RDWR | O_WRONLY)) 634 return ERR_PTR(-EINVAL); 635 636 if (permission(dentry->d_inode, oflag2acc[oflag & O_ACCMODE], NULL)) 637 return ERR_PTR(-EACCES); 638 639 filp = dentry_open(dentry, mqueue_mnt, oflag); 640 641 if (!IS_ERR(filp)) 642 dget(dentry); 643 644 return filp; 645 } 646 647 asmlinkage long sys_mq_open(const char __user *u_name, int oflag, mode_t mode, 648 struct mq_attr __user *u_attr) 649 { 650 struct dentry *dentry; 651 struct file *filp; 652 char *name; 653 int fd, error; 654 655 if (IS_ERR(name = getname(u_name))) 656 return PTR_ERR(name); 657 658 fd = get_unused_fd(); 659 if (fd < 0) 660 goto out_putname; 661 662 down(&mqueue_mnt->mnt_root->d_inode->i_sem); 663 dentry = lookup_one_len(name, mqueue_mnt->mnt_root, strlen(name)); 664 if (IS_ERR(dentry)) { 665 error = PTR_ERR(dentry); 666 goto out_err; 667 } 668 mntget(mqueue_mnt); 669 670 if (oflag & O_CREAT) { 671 if (dentry->d_inode) { /* entry already exists */ 672 filp = (oflag & O_EXCL) ? ERR_PTR(-EEXIST) : 673 do_open(dentry, oflag); 674 } else { 675 filp = do_create(mqueue_mnt->mnt_root, dentry, 676 oflag, mode, u_attr); 677 } 678 } else 679 filp = (dentry->d_inode) ? do_open(dentry, oflag) : 680 ERR_PTR(-ENOENT); 681 682 dput(dentry); 683 684 if (IS_ERR(filp)) { 685 error = PTR_ERR(filp); 686 goto out_putfd; 687 } 688 689 set_close_on_exec(fd, 1); 690 fd_install(fd, filp); 691 goto out_upsem; 692 693 out_putfd: 694 mntput(mqueue_mnt); 695 put_unused_fd(fd); 696 out_err: 697 fd = error; 698 out_upsem: 699 up(&mqueue_mnt->mnt_root->d_inode->i_sem); 700 out_putname: 701 putname(name); 702 return fd; 703 } 704 705 asmlinkage long sys_mq_unlink(const char __user *u_name) 706 { 707 int err; 708 char *name; 709 struct dentry *dentry; 710 struct inode *inode = NULL; 711 712 name = getname(u_name); 713 if (IS_ERR(name)) 714 return PTR_ERR(name); 715 716 down(&mqueue_mnt->mnt_root->d_inode->i_sem); 717 dentry = lookup_one_len(name, mqueue_mnt->mnt_root, strlen(name)); 718 if (IS_ERR(dentry)) { 719 err = PTR_ERR(dentry); 720 goto out_unlock; 721 } 722 723 if (!dentry->d_inode) { 724 err = -ENOENT; 725 goto out_err; 726 } 727 728 inode = dentry->d_inode; 729 if (inode) 730 atomic_inc(&inode->i_count); 731 732 err = vfs_unlink(dentry->d_parent->d_inode, dentry); 733 out_err: 734 dput(dentry); 735 736 out_unlock: 737 up(&mqueue_mnt->mnt_root->d_inode->i_sem); 738 putname(name); 739 if (inode) 740 iput(inode); 741 742 return err; 743 } 744 745 /* Pipelined send and receive functions. 746 * 747 * If a receiver finds no waiting message, then it registers itself in the 748 * list of waiting receivers. A sender checks that list before adding the new 749 * message into the message array. If there is a waiting receiver, then it 750 * bypasses the message array and directly hands the message over to the 751 * receiver. 752 * The receiver accepts the message and returns without grabbing the queue 753 * spinlock. Therefore an intermediate STATE_PENDING state and memory barriers 754 * are necessary. The same algorithm is used for sysv semaphores, see 755 * ipc/sem.c fore more details. 756 * 757 * The same algorithm is used for senders. 758 */ 759 760 /* pipelined_send() - send a message directly to the task waiting in 761 * sys_mq_timedreceive() (without inserting message into a queue). 762 */ 763 static inline void pipelined_send(struct mqueue_inode_info *info, 764 struct msg_msg *message, 765 struct ext_wait_queue *receiver) 766 { 767 receiver->msg = message; 768 list_del(&receiver->list); 769 receiver->state = STATE_PENDING; 770 wake_up_process(receiver->task); 771 smp_wmb(); 772 receiver->state = STATE_READY; 773 } 774 775 /* pipelined_receive() - if there is task waiting in sys_mq_timedsend() 776 * gets its message and put to the queue (we have one free place for sure). */ 777 static inline void pipelined_receive(struct mqueue_inode_info *info) 778 { 779 struct ext_wait_queue *sender = wq_get_first_waiter(info, SEND); 780 781 if (!sender) { 782 /* for poll */ 783 wake_up_interruptible(&info->wait_q); 784 return; 785 } 786 msg_insert(sender->msg, info); 787 list_del(&sender->list); 788 sender->state = STATE_PENDING; 789 wake_up_process(sender->task); 790 smp_wmb(); 791 sender->state = STATE_READY; 792 } 793 794 asmlinkage long sys_mq_timedsend(mqd_t mqdes, const char __user *u_msg_ptr, 795 size_t msg_len, unsigned int msg_prio, 796 const struct timespec __user *u_abs_timeout) 797 { 798 struct file *filp; 799 struct inode *inode; 800 struct ext_wait_queue wait; 801 struct ext_wait_queue *receiver; 802 struct msg_msg *msg_ptr; 803 struct mqueue_inode_info *info; 804 long timeout; 805 int ret; 806 807 if (unlikely(msg_prio >= (unsigned long) MQ_PRIO_MAX)) 808 return -EINVAL; 809 810 timeout = prepare_timeout(u_abs_timeout); 811 812 ret = -EBADF; 813 filp = fget(mqdes); 814 if (unlikely(!filp)) 815 goto out; 816 817 inode = filp->f_dentry->d_inode; 818 if (unlikely(filp->f_op != &mqueue_file_operations)) 819 goto out_fput; 820 info = MQUEUE_I(inode); 821 822 if (unlikely(!(filp->f_mode & FMODE_WRITE))) 823 goto out_fput; 824 825 if (unlikely(msg_len > info->attr.mq_msgsize)) { 826 ret = -EMSGSIZE; 827 goto out_fput; 828 } 829 830 /* First try to allocate memory, before doing anything with 831 * existing queues. */ 832 msg_ptr = load_msg(u_msg_ptr, msg_len); 833 if (IS_ERR(msg_ptr)) { 834 ret = PTR_ERR(msg_ptr); 835 goto out_fput; 836 } 837 msg_ptr->m_ts = msg_len; 838 msg_ptr->m_type = msg_prio; 839 840 spin_lock(&info->lock); 841 842 if (info->attr.mq_curmsgs == info->attr.mq_maxmsg) { 843 if (filp->f_flags & O_NONBLOCK) { 844 spin_unlock(&info->lock); 845 ret = -EAGAIN; 846 } else if (unlikely(timeout < 0)) { 847 spin_unlock(&info->lock); 848 ret = timeout; 849 } else { 850 wait.task = current; 851 wait.msg = (void *) msg_ptr; 852 wait.state = STATE_NONE; 853 ret = wq_sleep(info, SEND, timeout, &wait); 854 } 855 if (ret < 0) 856 free_msg(msg_ptr); 857 } else { 858 receiver = wq_get_first_waiter(info, RECV); 859 if (receiver) { 860 pipelined_send(info, msg_ptr, receiver); 861 } else { 862 /* adds message to the queue */ 863 msg_insert(msg_ptr, info); 864 __do_notify(info); 865 } 866 inode->i_atime = inode->i_mtime = inode->i_ctime = 867 CURRENT_TIME; 868 spin_unlock(&info->lock); 869 ret = 0; 870 } 871 out_fput: 872 fput(filp); 873 out: 874 return ret; 875 } 876 877 asmlinkage ssize_t sys_mq_timedreceive(mqd_t mqdes, char __user *u_msg_ptr, 878 size_t msg_len, unsigned int __user *u_msg_prio, 879 const struct timespec __user *u_abs_timeout) 880 { 881 long timeout; 882 ssize_t ret; 883 struct msg_msg *msg_ptr; 884 struct file *filp; 885 struct inode *inode; 886 struct mqueue_inode_info *info; 887 struct ext_wait_queue wait; 888 889 timeout = prepare_timeout(u_abs_timeout); 890 891 ret = -EBADF; 892 filp = fget(mqdes); 893 if (unlikely(!filp)) 894 goto out; 895 896 inode = filp->f_dentry->d_inode; 897 if (unlikely(filp->f_op != &mqueue_file_operations)) 898 goto out_fput; 899 info = MQUEUE_I(inode); 900 901 if (unlikely(!(filp->f_mode & FMODE_READ))) 902 goto out_fput; 903 904 /* checks if buffer is big enough */ 905 if (unlikely(msg_len < info->attr.mq_msgsize)) { 906 ret = -EMSGSIZE; 907 goto out_fput; 908 } 909 910 spin_lock(&info->lock); 911 if (info->attr.mq_curmsgs == 0) { 912 if (filp->f_flags & O_NONBLOCK) { 913 spin_unlock(&info->lock); 914 ret = -EAGAIN; 915 msg_ptr = NULL; 916 } else if (unlikely(timeout < 0)) { 917 spin_unlock(&info->lock); 918 ret = timeout; 919 msg_ptr = NULL; 920 } else { 921 wait.task = current; 922 wait.state = STATE_NONE; 923 ret = wq_sleep(info, RECV, timeout, &wait); 924 msg_ptr = wait.msg; 925 } 926 } else { 927 msg_ptr = msg_get(info); 928 929 inode->i_atime = inode->i_mtime = inode->i_ctime = 930 CURRENT_TIME; 931 932 /* There is now free space in queue. */ 933 pipelined_receive(info); 934 spin_unlock(&info->lock); 935 ret = 0; 936 } 937 if (ret == 0) { 938 ret = msg_ptr->m_ts; 939 940 if ((u_msg_prio && put_user(msg_ptr->m_type, u_msg_prio)) || 941 store_msg(u_msg_ptr, msg_ptr, msg_ptr->m_ts)) { 942 ret = -EFAULT; 943 } 944 free_msg(msg_ptr); 945 } 946 out_fput: 947 fput(filp); 948 out: 949 return ret; 950 } 951 952 /* 953 * Notes: the case when user wants us to deregister (with NULL as pointer) 954 * and he isn't currently owner of notification, will be silently discarded. 955 * It isn't explicitly defined in the POSIX. 956 */ 957 asmlinkage long sys_mq_notify(mqd_t mqdes, 958 const struct sigevent __user *u_notification) 959 { 960 int ret; 961 struct file *filp; 962 struct sock *sock; 963 struct inode *inode; 964 struct sigevent notification; 965 struct mqueue_inode_info *info; 966 struct sk_buff *nc; 967 968 nc = NULL; 969 sock = NULL; 970 if (u_notification != NULL) { 971 if (copy_from_user(¬ification, u_notification, 972 sizeof(struct sigevent))) 973 return -EFAULT; 974 975 if (unlikely(notification.sigev_notify != SIGEV_NONE && 976 notification.sigev_notify != SIGEV_SIGNAL && 977 notification.sigev_notify != SIGEV_THREAD)) 978 return -EINVAL; 979 if (notification.sigev_notify == SIGEV_SIGNAL && 980 !valid_signal(notification.sigev_signo)) { 981 return -EINVAL; 982 } 983 if (notification.sigev_notify == SIGEV_THREAD) { 984 /* create the notify skb */ 985 nc = alloc_skb(NOTIFY_COOKIE_LEN, GFP_KERNEL); 986 ret = -ENOMEM; 987 if (!nc) 988 goto out; 989 ret = -EFAULT; 990 if (copy_from_user(nc->data, 991 notification.sigev_value.sival_ptr, 992 NOTIFY_COOKIE_LEN)) { 993 goto out; 994 } 995 996 /* TODO: add a header? */ 997 skb_put(nc, NOTIFY_COOKIE_LEN); 998 /* and attach it to the socket */ 999 retry: 1000 filp = fget(notification.sigev_signo); 1001 ret = -EBADF; 1002 if (!filp) 1003 goto out; 1004 sock = netlink_getsockbyfilp(filp); 1005 fput(filp); 1006 if (IS_ERR(sock)) { 1007 ret = PTR_ERR(sock); 1008 sock = NULL; 1009 goto out; 1010 } 1011 1012 ret = netlink_attachskb(sock, nc, 0, MAX_SCHEDULE_TIMEOUT); 1013 if (ret == 1) 1014 goto retry; 1015 if (ret) { 1016 sock = NULL; 1017 nc = NULL; 1018 goto out; 1019 } 1020 } 1021 } 1022 1023 ret = -EBADF; 1024 filp = fget(mqdes); 1025 if (!filp) 1026 goto out; 1027 1028 inode = filp->f_dentry->d_inode; 1029 if (unlikely(filp->f_op != &mqueue_file_operations)) 1030 goto out_fput; 1031 info = MQUEUE_I(inode); 1032 1033 ret = 0; 1034 spin_lock(&info->lock); 1035 if (u_notification == NULL) { 1036 if (info->notify_owner == current->tgid) { 1037 remove_notification(info); 1038 inode->i_atime = inode->i_ctime = CURRENT_TIME; 1039 } 1040 } else if (info->notify_owner != 0) { 1041 ret = -EBUSY; 1042 } else { 1043 switch (notification.sigev_notify) { 1044 case SIGEV_NONE: 1045 info->notify.sigev_notify = SIGEV_NONE; 1046 break; 1047 case SIGEV_THREAD: 1048 info->notify_sock = sock; 1049 info->notify_cookie = nc; 1050 sock = NULL; 1051 nc = NULL; 1052 info->notify.sigev_notify = SIGEV_THREAD; 1053 break; 1054 case SIGEV_SIGNAL: 1055 info->notify.sigev_signo = notification.sigev_signo; 1056 info->notify.sigev_value = notification.sigev_value; 1057 info->notify.sigev_notify = SIGEV_SIGNAL; 1058 break; 1059 } 1060 info->notify_owner = current->tgid; 1061 inode->i_atime = inode->i_ctime = CURRENT_TIME; 1062 } 1063 spin_unlock(&info->lock); 1064 out_fput: 1065 fput(filp); 1066 out: 1067 if (sock) { 1068 netlink_detachskb(sock, nc); 1069 } else if (nc) { 1070 dev_kfree_skb(nc); 1071 } 1072 return ret; 1073 } 1074 1075 asmlinkage long sys_mq_getsetattr(mqd_t mqdes, 1076 const struct mq_attr __user *u_mqstat, 1077 struct mq_attr __user *u_omqstat) 1078 { 1079 int ret; 1080 struct mq_attr mqstat, omqstat; 1081 struct file *filp; 1082 struct inode *inode; 1083 struct mqueue_inode_info *info; 1084 1085 if (u_mqstat != NULL) { 1086 if (copy_from_user(&mqstat, u_mqstat, sizeof(struct mq_attr))) 1087 return -EFAULT; 1088 if (mqstat.mq_flags & (~O_NONBLOCK)) 1089 return -EINVAL; 1090 } 1091 1092 ret = -EBADF; 1093 filp = fget(mqdes); 1094 if (!filp) 1095 goto out; 1096 1097 inode = filp->f_dentry->d_inode; 1098 if (unlikely(filp->f_op != &mqueue_file_operations)) 1099 goto out_fput; 1100 info = MQUEUE_I(inode); 1101 1102 spin_lock(&info->lock); 1103 1104 omqstat = info->attr; 1105 omqstat.mq_flags = filp->f_flags & O_NONBLOCK; 1106 if (u_mqstat) { 1107 if (mqstat.mq_flags & O_NONBLOCK) 1108 filp->f_flags |= O_NONBLOCK; 1109 else 1110 filp->f_flags &= ~O_NONBLOCK; 1111 1112 inode->i_atime = inode->i_ctime = CURRENT_TIME; 1113 } 1114 1115 spin_unlock(&info->lock); 1116 1117 ret = 0; 1118 if (u_omqstat != NULL && copy_to_user(u_omqstat, &omqstat, 1119 sizeof(struct mq_attr))) 1120 ret = -EFAULT; 1121 1122 out_fput: 1123 fput(filp); 1124 out: 1125 return ret; 1126 } 1127 1128 static struct inode_operations mqueue_dir_inode_operations = { 1129 .lookup = simple_lookup, 1130 .create = mqueue_create, 1131 .unlink = mqueue_unlink, 1132 }; 1133 1134 static struct file_operations mqueue_file_operations = { 1135 .flush = mqueue_flush_file, 1136 .poll = mqueue_poll_file, 1137 .read = mqueue_read_file, 1138 }; 1139 1140 static struct super_operations mqueue_super_ops = { 1141 .alloc_inode = mqueue_alloc_inode, 1142 .destroy_inode = mqueue_destroy_inode, 1143 .statfs = simple_statfs, 1144 .delete_inode = mqueue_delete_inode, 1145 .drop_inode = generic_delete_inode, 1146 }; 1147 1148 static struct file_system_type mqueue_fs_type = { 1149 .name = "mqueue", 1150 .get_sb = mqueue_get_sb, 1151 .kill_sb = kill_litter_super, 1152 }; 1153 1154 static int msg_max_limit_min = DFLT_MSGMAX; 1155 static int msg_max_limit_max = HARD_MSGMAX; 1156 1157 static int msg_maxsize_limit_min = DFLT_MSGSIZEMAX; 1158 static int msg_maxsize_limit_max = INT_MAX; 1159 1160 static ctl_table mq_sysctls[] = { 1161 { 1162 .ctl_name = CTL_QUEUESMAX, 1163 .procname = "queues_max", 1164 .data = &queues_max, 1165 .maxlen = sizeof(int), 1166 .mode = 0644, 1167 .proc_handler = &proc_dointvec, 1168 }, 1169 { 1170 .ctl_name = CTL_MSGMAX, 1171 .procname = "msg_max", 1172 .data = &msg_max, 1173 .maxlen = sizeof(int), 1174 .mode = 0644, 1175 .proc_handler = &proc_dointvec_minmax, 1176 .extra1 = &msg_max_limit_min, 1177 .extra2 = &msg_max_limit_max, 1178 }, 1179 { 1180 .ctl_name = CTL_MSGSIZEMAX, 1181 .procname = "msgsize_max", 1182 .data = &msgsize_max, 1183 .maxlen = sizeof(int), 1184 .mode = 0644, 1185 .proc_handler = &proc_dointvec_minmax, 1186 .extra1 = &msg_maxsize_limit_min, 1187 .extra2 = &msg_maxsize_limit_max, 1188 }, 1189 { .ctl_name = 0 } 1190 }; 1191 1192 static ctl_table mq_sysctl_dir[] = { 1193 { 1194 .ctl_name = FS_MQUEUE, 1195 .procname = "mqueue", 1196 .mode = 0555, 1197 .child = mq_sysctls, 1198 }, 1199 { .ctl_name = 0 } 1200 }; 1201 1202 static ctl_table mq_sysctl_root[] = { 1203 { 1204 .ctl_name = CTL_FS, 1205 .procname = "fs", 1206 .mode = 0555, 1207 .child = mq_sysctl_dir, 1208 }, 1209 { .ctl_name = 0 } 1210 }; 1211 1212 static int __init init_mqueue_fs(void) 1213 { 1214 int error; 1215 1216 mqueue_inode_cachep = kmem_cache_create("mqueue_inode_cache", 1217 sizeof(struct mqueue_inode_info), 0, 1218 SLAB_HWCACHE_ALIGN, init_once, NULL); 1219 if (mqueue_inode_cachep == NULL) 1220 return -ENOMEM; 1221 1222 /* ignore failues - they are not fatal */ 1223 mq_sysctl_table = register_sysctl_table(mq_sysctl_root, 0); 1224 1225 error = register_filesystem(&mqueue_fs_type); 1226 if (error) 1227 goto out_sysctl; 1228 1229 if (IS_ERR(mqueue_mnt = kern_mount(&mqueue_fs_type))) { 1230 error = PTR_ERR(mqueue_mnt); 1231 goto out_filesystem; 1232 } 1233 1234 /* internal initialization - not common for vfs */ 1235 queues_count = 0; 1236 spin_lock_init(&mq_lock); 1237 1238 return 0; 1239 1240 out_filesystem: 1241 unregister_filesystem(&mqueue_fs_type); 1242 out_sysctl: 1243 if (mq_sysctl_table) 1244 unregister_sysctl_table(mq_sysctl_table); 1245 if (kmem_cache_destroy(mqueue_inode_cachep)) { 1246 printk(KERN_INFO 1247 "mqueue_inode_cache: not all structures were freed\n"); 1248 } 1249 return error; 1250 } 1251 1252 __initcall(init_mqueue_fs); 1253