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@gmail.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 * Audit: George Wilson (ltcgcw@us.ibm.com) 12 * 13 * This file is released under the GPL. 14 */ 15 16 #include <linux/capability.h> 17 #include <linux/init.h> 18 #include <linux/pagemap.h> 19 #include <linux/file.h> 20 #include <linux/mount.h> 21 #include <linux/namei.h> 22 #include <linux/sysctl.h> 23 #include <linux/poll.h> 24 #include <linux/mqueue.h> 25 #include <linux/msg.h> 26 #include <linux/skbuff.h> 27 #include <linux/netlink.h> 28 #include <linux/syscalls.h> 29 #include <linux/audit.h> 30 #include <linux/signal.h> 31 #include <linux/mutex.h> 32 33 #include <net/sock.h> 34 #include "util.h" 35 36 #define MQUEUE_MAGIC 0x19800202 37 #define DIRENT_SIZE 20 38 #define FILENT_SIZE 80 39 40 #define SEND 0 41 #define RECV 1 42 43 #define STATE_NONE 0 44 #define STATE_PENDING 1 45 #define STATE_READY 2 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 54 struct ext_wait_queue { /* queue of sleeping tasks */ 55 struct task_struct *task; 56 struct list_head list; 57 struct msg_msg *msg; /* ptr of loaded message */ 58 int state; /* one of STATE_* values */ 59 }; 60 61 struct mqueue_inode_info { 62 spinlock_t lock; 63 struct inode vfs_inode; 64 wait_queue_head_t wait_q; 65 66 struct msg_msg **messages; 67 struct mq_attr attr; 68 69 struct sigevent notify; 70 struct pid* notify_owner; 71 struct user_struct *user; /* user who created, for accounting */ 72 struct sock *notify_sock; 73 struct sk_buff *notify_cookie; 74 75 /* for tasks waiting for free space and messages, respectively */ 76 struct ext_wait_queue e_wait_q[2]; 77 78 unsigned long qsize; /* size of queue in memory (sum of all msgs) */ 79 }; 80 81 static const struct inode_operations mqueue_dir_inode_operations; 82 static const struct file_operations mqueue_file_operations; 83 static struct super_operations mqueue_super_ops; 84 static void remove_notification(struct mqueue_inode_info *info); 85 86 static spinlock_t mq_lock; 87 static struct kmem_cache *mqueue_inode_cachep; 88 static struct vfsmount *mqueue_mnt; 89 90 static unsigned int queues_count; 91 static unsigned int queues_max = DFLT_QUEUESMAX; 92 static unsigned int msg_max = DFLT_MSGMAX; 93 static unsigned int msgsize_max = DFLT_MSGSIZEMAX; 94 95 static struct ctl_table_header * mq_sysctl_table; 96 97 static inline struct mqueue_inode_info *MQUEUE_I(struct inode *inode) 98 { 99 return container_of(inode, struct mqueue_inode_info, vfs_inode); 100 } 101 102 static struct inode *mqueue_get_inode(struct super_block *sb, int mode, 103 struct mq_attr *attr) 104 { 105 struct inode *inode; 106 107 inode = new_inode(sb); 108 if (inode) { 109 inode->i_mode = mode; 110 inode->i_uid = current->fsuid; 111 inode->i_gid = current->fsgid; 112 inode->i_blocks = 0; 113 inode->i_mtime = inode->i_ctime = inode->i_atime = 114 CURRENT_TIME; 115 116 if (S_ISREG(mode)) { 117 struct mqueue_inode_info *info; 118 struct task_struct *p = current; 119 struct user_struct *u = p->user; 120 unsigned long mq_bytes, mq_msg_tblsz; 121 122 inode->i_fop = &mqueue_file_operations; 123 inode->i_size = FILENT_SIZE; 124 /* mqueue specific info */ 125 info = MQUEUE_I(inode); 126 spin_lock_init(&info->lock); 127 init_waitqueue_head(&info->wait_q); 128 INIT_LIST_HEAD(&info->e_wait_q[0].list); 129 INIT_LIST_HEAD(&info->e_wait_q[1].list); 130 info->messages = NULL; 131 info->notify_owner = NULL; 132 info->qsize = 0; 133 info->user = NULL; /* set when all is ok */ 134 memset(&info->attr, 0, sizeof(info->attr)); 135 info->attr.mq_maxmsg = DFLT_MSGMAX; 136 info->attr.mq_msgsize = DFLT_MSGSIZEMAX; 137 if (attr) { 138 info->attr.mq_maxmsg = attr->mq_maxmsg; 139 info->attr.mq_msgsize = attr->mq_msgsize; 140 } 141 mq_msg_tblsz = info->attr.mq_maxmsg * sizeof(struct msg_msg *); 142 mq_bytes = (mq_msg_tblsz + 143 (info->attr.mq_maxmsg * info->attr.mq_msgsize)); 144 145 spin_lock(&mq_lock); 146 if (u->mq_bytes + mq_bytes < u->mq_bytes || 147 u->mq_bytes + mq_bytes > 148 p->signal->rlim[RLIMIT_MSGQUEUE].rlim_cur) { 149 spin_unlock(&mq_lock); 150 goto out_inode; 151 } 152 u->mq_bytes += mq_bytes; 153 spin_unlock(&mq_lock); 154 155 info->messages = kmalloc(mq_msg_tblsz, GFP_KERNEL); 156 if (!info->messages) { 157 spin_lock(&mq_lock); 158 u->mq_bytes -= mq_bytes; 159 spin_unlock(&mq_lock); 160 goto out_inode; 161 } 162 /* all is ok */ 163 info->user = get_uid(u); 164 } else if (S_ISDIR(mode)) { 165 inc_nlink(inode); 166 /* Some things misbehave if size == 0 on a directory */ 167 inode->i_size = 2 * DIRENT_SIZE; 168 inode->i_op = &mqueue_dir_inode_operations; 169 inode->i_fop = &simple_dir_operations; 170 } 171 } 172 return inode; 173 out_inode: 174 make_bad_inode(inode); 175 iput(inode); 176 return NULL; 177 } 178 179 static int mqueue_fill_super(struct super_block *sb, void *data, int silent) 180 { 181 struct inode *inode; 182 183 sb->s_blocksize = PAGE_CACHE_SIZE; 184 sb->s_blocksize_bits = PAGE_CACHE_SHIFT; 185 sb->s_magic = MQUEUE_MAGIC; 186 sb->s_op = &mqueue_super_ops; 187 188 inode = mqueue_get_inode(sb, S_IFDIR | S_ISVTX | S_IRWXUGO, NULL); 189 if (!inode) 190 return -ENOMEM; 191 192 sb->s_root = d_alloc_root(inode); 193 if (!sb->s_root) { 194 iput(inode); 195 return -ENOMEM; 196 } 197 198 return 0; 199 } 200 201 static int mqueue_get_sb(struct file_system_type *fs_type, 202 int flags, const char *dev_name, 203 void *data, struct vfsmount *mnt) 204 { 205 return get_sb_single(fs_type, flags, data, mqueue_fill_super, mnt); 206 } 207 208 static void init_once(struct kmem_cache *cachep, void *foo) 209 { 210 struct mqueue_inode_info *p = (struct mqueue_inode_info *) foo; 211 212 inode_init_once(&p->vfs_inode); 213 } 214 215 static struct inode *mqueue_alloc_inode(struct super_block *sb) 216 { 217 struct mqueue_inode_info *ei; 218 219 ei = kmem_cache_alloc(mqueue_inode_cachep, GFP_KERNEL); 220 if (!ei) 221 return NULL; 222 return &ei->vfs_inode; 223 } 224 225 static void mqueue_destroy_inode(struct inode *inode) 226 { 227 kmem_cache_free(mqueue_inode_cachep, MQUEUE_I(inode)); 228 } 229 230 static void mqueue_delete_inode(struct inode *inode) 231 { 232 struct mqueue_inode_info *info; 233 struct user_struct *user; 234 unsigned long mq_bytes; 235 int i; 236 237 if (S_ISDIR(inode->i_mode)) { 238 clear_inode(inode); 239 return; 240 } 241 info = MQUEUE_I(inode); 242 spin_lock(&info->lock); 243 for (i = 0; i < info->attr.mq_curmsgs; i++) 244 free_msg(info->messages[i]); 245 kfree(info->messages); 246 spin_unlock(&info->lock); 247 248 clear_inode(inode); 249 250 mq_bytes = (info->attr.mq_maxmsg * sizeof(struct msg_msg *) + 251 (info->attr.mq_maxmsg * info->attr.mq_msgsize)); 252 user = info->user; 253 if (user) { 254 spin_lock(&mq_lock); 255 user->mq_bytes -= mq_bytes; 256 queues_count--; 257 spin_unlock(&mq_lock); 258 free_uid(user); 259 } 260 } 261 262 static int mqueue_create(struct inode *dir, struct dentry *dentry, 263 int mode, struct nameidata *nd) 264 { 265 struct inode *inode; 266 struct mq_attr *attr = dentry->d_fsdata; 267 int error; 268 269 spin_lock(&mq_lock); 270 if (queues_count >= queues_max && !capable(CAP_SYS_RESOURCE)) { 271 error = -ENOSPC; 272 goto out_lock; 273 } 274 queues_count++; 275 spin_unlock(&mq_lock); 276 277 inode = mqueue_get_inode(dir->i_sb, mode, attr); 278 if (!inode) { 279 error = -ENOMEM; 280 spin_lock(&mq_lock); 281 queues_count--; 282 goto out_lock; 283 } 284 285 dir->i_size += DIRENT_SIZE; 286 dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME; 287 288 d_instantiate(dentry, inode); 289 dget(dentry); 290 return 0; 291 out_lock: 292 spin_unlock(&mq_lock); 293 return error; 294 } 295 296 static int mqueue_unlink(struct inode *dir, struct dentry *dentry) 297 { 298 struct inode *inode = dentry->d_inode; 299 300 dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME; 301 dir->i_size -= DIRENT_SIZE; 302 drop_nlink(inode); 303 dput(dentry); 304 return 0; 305 } 306 307 /* 308 * This is routine for system read from queue file. 309 * To avoid mess with doing here some sort of mq_receive we allow 310 * to read only queue size & notification info (the only values 311 * that are interesting from user point of view and aren't accessible 312 * through std routines) 313 */ 314 static ssize_t mqueue_read_file(struct file *filp, char __user *u_data, 315 size_t count, loff_t * off) 316 { 317 struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode); 318 char buffer[FILENT_SIZE]; 319 size_t slen; 320 loff_t o; 321 322 if (!count) 323 return 0; 324 325 spin_lock(&info->lock); 326 snprintf(buffer, sizeof(buffer), 327 "QSIZE:%-10lu NOTIFY:%-5d SIGNO:%-5d NOTIFY_PID:%-6d\n", 328 info->qsize, 329 info->notify_owner ? info->notify.sigev_notify : 0, 330 (info->notify_owner && 331 info->notify.sigev_notify == SIGEV_SIGNAL) ? 332 info->notify.sigev_signo : 0, 333 pid_nr(info->notify_owner)); 334 spin_unlock(&info->lock); 335 buffer[sizeof(buffer)-1] = '\0'; 336 slen = strlen(buffer)+1; 337 338 o = *off; 339 if (o > slen) 340 return 0; 341 342 if (o + count > slen) 343 count = slen - o; 344 345 if (copy_to_user(u_data, buffer + o, count)) 346 return -EFAULT; 347 348 *off = o + count; 349 filp->f_path.dentry->d_inode->i_atime = filp->f_path.dentry->d_inode->i_ctime = CURRENT_TIME; 350 return count; 351 } 352 353 static int mqueue_flush_file(struct file *filp, fl_owner_t id) 354 { 355 struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode); 356 357 spin_lock(&info->lock); 358 if (task_tgid(current) == info->notify_owner) 359 remove_notification(info); 360 361 spin_unlock(&info->lock); 362 return 0; 363 } 364 365 static unsigned int mqueue_poll_file(struct file *filp, struct poll_table_struct *poll_tab) 366 { 367 struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode); 368 int retval = 0; 369 370 poll_wait(filp, &info->wait_q, poll_tab); 371 372 spin_lock(&info->lock); 373 if (info->attr.mq_curmsgs) 374 retval = POLLIN | POLLRDNORM; 375 376 if (info->attr.mq_curmsgs < info->attr.mq_maxmsg) 377 retval |= POLLOUT | POLLWRNORM; 378 spin_unlock(&info->lock); 379 380 return retval; 381 } 382 383 /* Adds current to info->e_wait_q[sr] before element with smaller prio */ 384 static void wq_add(struct mqueue_inode_info *info, int sr, 385 struct ext_wait_queue *ewp) 386 { 387 struct ext_wait_queue *walk; 388 389 ewp->task = current; 390 391 list_for_each_entry(walk, &info->e_wait_q[sr].list, list) { 392 if (walk->task->static_prio <= current->static_prio) { 393 list_add_tail(&ewp->list, &walk->list); 394 return; 395 } 396 } 397 list_add_tail(&ewp->list, &info->e_wait_q[sr].list); 398 } 399 400 /* 401 * Puts current task to sleep. Caller must hold queue lock. After return 402 * lock isn't held. 403 * sr: SEND or RECV 404 */ 405 static int wq_sleep(struct mqueue_inode_info *info, int sr, 406 long timeout, struct ext_wait_queue *ewp) 407 { 408 int retval; 409 signed long time; 410 411 wq_add(info, sr, ewp); 412 413 for (;;) { 414 set_current_state(TASK_INTERRUPTIBLE); 415 416 spin_unlock(&info->lock); 417 time = schedule_timeout(timeout); 418 419 while (ewp->state == STATE_PENDING) 420 cpu_relax(); 421 422 if (ewp->state == STATE_READY) { 423 retval = 0; 424 goto out; 425 } 426 spin_lock(&info->lock); 427 if (ewp->state == STATE_READY) { 428 retval = 0; 429 goto out_unlock; 430 } 431 if (signal_pending(current)) { 432 retval = -ERESTARTSYS; 433 break; 434 } 435 if (time == 0) { 436 retval = -ETIMEDOUT; 437 break; 438 } 439 } 440 list_del(&ewp->list); 441 out_unlock: 442 spin_unlock(&info->lock); 443 out: 444 return retval; 445 } 446 447 /* 448 * Returns waiting task that should be serviced first or NULL if none exists 449 */ 450 static struct ext_wait_queue *wq_get_first_waiter( 451 struct mqueue_inode_info *info, int sr) 452 { 453 struct list_head *ptr; 454 455 ptr = info->e_wait_q[sr].list.prev; 456 if (ptr == &info->e_wait_q[sr].list) 457 return NULL; 458 return list_entry(ptr, struct ext_wait_queue, list); 459 } 460 461 /* Auxiliary functions to manipulate messages' list */ 462 static void msg_insert(struct msg_msg *ptr, struct mqueue_inode_info *info) 463 { 464 int k; 465 466 k = info->attr.mq_curmsgs - 1; 467 while (k >= 0 && info->messages[k]->m_type >= ptr->m_type) { 468 info->messages[k + 1] = info->messages[k]; 469 k--; 470 } 471 info->attr.mq_curmsgs++; 472 info->qsize += ptr->m_ts; 473 info->messages[k + 1] = ptr; 474 } 475 476 static inline struct msg_msg *msg_get(struct mqueue_inode_info *info) 477 { 478 info->qsize -= info->messages[--info->attr.mq_curmsgs]->m_ts; 479 return info->messages[info->attr.mq_curmsgs]; 480 } 481 482 static inline void set_cookie(struct sk_buff *skb, char code) 483 { 484 ((char*)skb->data)[NOTIFY_COOKIE_LEN-1] = code; 485 } 486 487 /* 488 * The next function is only to split too long sys_mq_timedsend 489 */ 490 static void __do_notify(struct mqueue_inode_info *info) 491 { 492 /* notification 493 * invoked when there is registered process and there isn't process 494 * waiting synchronously for message AND state of queue changed from 495 * empty to not empty. Here we are sure that no one is waiting 496 * synchronously. */ 497 if (info->notify_owner && 498 info->attr.mq_curmsgs == 1) { 499 struct siginfo sig_i; 500 switch (info->notify.sigev_notify) { 501 case SIGEV_NONE: 502 break; 503 case SIGEV_SIGNAL: 504 /* sends signal */ 505 506 sig_i.si_signo = info->notify.sigev_signo; 507 sig_i.si_errno = 0; 508 sig_i.si_code = SI_MESGQ; 509 sig_i.si_value = info->notify.sigev_value; 510 sig_i.si_pid = current->tgid; 511 sig_i.si_uid = current->uid; 512 513 kill_pid_info(info->notify.sigev_signo, 514 &sig_i, info->notify_owner); 515 break; 516 case SIGEV_THREAD: 517 set_cookie(info->notify_cookie, NOTIFY_WOKENUP); 518 netlink_sendskb(info->notify_sock, info->notify_cookie); 519 break; 520 } 521 /* after notification unregisters process */ 522 put_pid(info->notify_owner); 523 info->notify_owner = NULL; 524 } 525 wake_up(&info->wait_q); 526 } 527 528 static long prepare_timeout(const struct timespec __user *u_arg) 529 { 530 struct timespec ts, nowts; 531 long timeout; 532 533 if (u_arg) { 534 if (unlikely(copy_from_user(&ts, u_arg, 535 sizeof(struct timespec)))) 536 return -EFAULT; 537 538 if (unlikely(ts.tv_nsec < 0 || ts.tv_sec < 0 539 || ts.tv_nsec >= NSEC_PER_SEC)) 540 return -EINVAL; 541 nowts = CURRENT_TIME; 542 /* first subtract as jiffies can't be too big */ 543 ts.tv_sec -= nowts.tv_sec; 544 if (ts.tv_nsec < nowts.tv_nsec) { 545 ts.tv_nsec += NSEC_PER_SEC; 546 ts.tv_sec--; 547 } 548 ts.tv_nsec -= nowts.tv_nsec; 549 if (ts.tv_sec < 0) 550 return 0; 551 552 timeout = timespec_to_jiffies(&ts) + 1; 553 } else 554 return MAX_SCHEDULE_TIMEOUT; 555 556 return timeout; 557 } 558 559 static void remove_notification(struct mqueue_inode_info *info) 560 { 561 if (info->notify_owner != NULL && 562 info->notify.sigev_notify == SIGEV_THREAD) { 563 set_cookie(info->notify_cookie, NOTIFY_REMOVED); 564 netlink_sendskb(info->notify_sock, info->notify_cookie); 565 } 566 put_pid(info->notify_owner); 567 info->notify_owner = NULL; 568 } 569 570 static int mq_attr_ok(struct mq_attr *attr) 571 { 572 if (attr->mq_maxmsg <= 0 || attr->mq_msgsize <= 0) 573 return 0; 574 if (capable(CAP_SYS_RESOURCE)) { 575 if (attr->mq_maxmsg > HARD_MSGMAX) 576 return 0; 577 } else { 578 if (attr->mq_maxmsg > msg_max || 579 attr->mq_msgsize > msgsize_max) 580 return 0; 581 } 582 /* check for overflow */ 583 if (attr->mq_msgsize > ULONG_MAX/attr->mq_maxmsg) 584 return 0; 585 if ((unsigned long)(attr->mq_maxmsg * attr->mq_msgsize) + 586 (attr->mq_maxmsg * sizeof (struct msg_msg *)) < 587 (unsigned long)(attr->mq_maxmsg * attr->mq_msgsize)) 588 return 0; 589 return 1; 590 } 591 592 /* 593 * Invoked when creating a new queue via sys_mq_open 594 */ 595 static struct file *do_create(struct dentry *dir, struct dentry *dentry, 596 int oflag, mode_t mode, struct mq_attr __user *u_attr) 597 { 598 struct mq_attr attr; 599 int ret; 600 601 if (u_attr) { 602 ret = -EFAULT; 603 if (copy_from_user(&attr, u_attr, sizeof(attr))) 604 goto out; 605 ret = -EINVAL; 606 if (!mq_attr_ok(&attr)) 607 goto out; 608 /* store for use during create */ 609 dentry->d_fsdata = &attr; 610 } 611 612 mode &= ~current->fs->umask; 613 ret = vfs_create(dir->d_inode, dentry, mode, NULL); 614 dentry->d_fsdata = NULL; 615 if (ret) 616 goto out; 617 618 return dentry_open(dentry, mqueue_mnt, oflag); 619 620 out: 621 dput(dentry); 622 mntput(mqueue_mnt); 623 return ERR_PTR(ret); 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 }; 631 632 if ((oflag & O_ACCMODE) == (O_RDWR | O_WRONLY)) { 633 dput(dentry); 634 mntput(mqueue_mnt); 635 return ERR_PTR(-EINVAL); 636 } 637 638 if (permission(dentry->d_inode, oflag2acc[oflag & O_ACCMODE], NULL)) { 639 dput(dentry); 640 mntput(mqueue_mnt); 641 return ERR_PTR(-EACCES); 642 } 643 644 return dentry_open(dentry, mqueue_mnt, oflag); 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 error = audit_mq_open(oflag, mode, u_attr); 656 if (error != 0) 657 return 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 audit_inode(name, dentry->d_inode); 677 error = -EEXIST; 678 if (oflag & O_EXCL) 679 goto out; 680 filp = do_open(dentry, oflag); 681 } else { 682 filp = do_create(mqueue_mnt->mnt_root, dentry, 683 oflag, mode, u_attr); 684 } 685 } else { 686 error = -ENOENT; 687 if (!dentry->d_inode) 688 goto out; 689 audit_inode(name, dentry->d_inode); 690 filp = do_open(dentry, oflag); 691 } 692 693 if (IS_ERR(filp)) { 694 error = PTR_ERR(filp); 695 goto out_putfd; 696 } 697 698 set_close_on_exec(fd, 1); 699 fd_install(fd, filp); 700 goto out_upsem; 701 702 out: 703 dput(dentry); 704 mntput(mqueue_mnt); 705 out_putfd: 706 put_unused_fd(fd); 707 out_err: 708 fd = error; 709 out_upsem: 710 mutex_unlock(&mqueue_mnt->mnt_root->d_inode->i_mutex); 711 out_putname: 712 putname(name); 713 return fd; 714 } 715 716 asmlinkage long sys_mq_unlink(const char __user *u_name) 717 { 718 int err; 719 char *name; 720 struct dentry *dentry; 721 struct inode *inode = NULL; 722 723 name = getname(u_name); 724 if (IS_ERR(name)) 725 return PTR_ERR(name); 726 727 mutex_lock_nested(&mqueue_mnt->mnt_root->d_inode->i_mutex, 728 I_MUTEX_PARENT); 729 dentry = lookup_one_len(name, mqueue_mnt->mnt_root, strlen(name)); 730 if (IS_ERR(dentry)) { 731 err = PTR_ERR(dentry); 732 goto out_unlock; 733 } 734 735 if (!dentry->d_inode) { 736 err = -ENOENT; 737 goto out_err; 738 } 739 740 inode = dentry->d_inode; 741 if (inode) 742 atomic_inc(&inode->i_count); 743 744 err = vfs_unlink(dentry->d_parent->d_inode, dentry); 745 out_err: 746 dput(dentry); 747 748 out_unlock: 749 mutex_unlock(&mqueue_mnt->mnt_root->d_inode->i_mutex); 750 putname(name); 751 if (inode) 752 iput(inode); 753 754 return err; 755 } 756 757 /* Pipelined send and receive functions. 758 * 759 * If a receiver finds no waiting message, then it registers itself in the 760 * list of waiting receivers. A sender checks that list before adding the new 761 * message into the message array. If there is a waiting receiver, then it 762 * bypasses the message array and directly hands the message over to the 763 * receiver. 764 * The receiver accepts the message and returns without grabbing the queue 765 * spinlock. Therefore an intermediate STATE_PENDING state and memory barriers 766 * are necessary. The same algorithm is used for sysv semaphores, see 767 * ipc/sem.c for more details. 768 * 769 * The same algorithm is used for senders. 770 */ 771 772 /* pipelined_send() - send a message directly to the task waiting in 773 * sys_mq_timedreceive() (without inserting message into a queue). 774 */ 775 static inline void pipelined_send(struct mqueue_inode_info *info, 776 struct msg_msg *message, 777 struct ext_wait_queue *receiver) 778 { 779 receiver->msg = message; 780 list_del(&receiver->list); 781 receiver->state = STATE_PENDING; 782 wake_up_process(receiver->task); 783 smp_wmb(); 784 receiver->state = STATE_READY; 785 } 786 787 /* pipelined_receive() - if there is task waiting in sys_mq_timedsend() 788 * gets its message and put to the queue (we have one free place for sure). */ 789 static inline void pipelined_receive(struct mqueue_inode_info *info) 790 { 791 struct ext_wait_queue *sender = wq_get_first_waiter(info, SEND); 792 793 if (!sender) { 794 /* for poll */ 795 wake_up_interruptible(&info->wait_q); 796 return; 797 } 798 msg_insert(sender->msg, info); 799 list_del(&sender->list); 800 sender->state = STATE_PENDING; 801 wake_up_process(sender->task); 802 smp_wmb(); 803 sender->state = STATE_READY; 804 } 805 806 asmlinkage long sys_mq_timedsend(mqd_t mqdes, const char __user *u_msg_ptr, 807 size_t msg_len, unsigned int msg_prio, 808 const struct timespec __user *u_abs_timeout) 809 { 810 struct file *filp; 811 struct inode *inode; 812 struct ext_wait_queue wait; 813 struct ext_wait_queue *receiver; 814 struct msg_msg *msg_ptr; 815 struct mqueue_inode_info *info; 816 long timeout; 817 int ret; 818 819 ret = audit_mq_timedsend(mqdes, msg_len, msg_prio, u_abs_timeout); 820 if (ret != 0) 821 return ret; 822 823 if (unlikely(msg_prio >= (unsigned long) MQ_PRIO_MAX)) 824 return -EINVAL; 825 826 timeout = prepare_timeout(u_abs_timeout); 827 828 ret = -EBADF; 829 filp = fget(mqdes); 830 if (unlikely(!filp)) 831 goto out; 832 833 inode = filp->f_path.dentry->d_inode; 834 if (unlikely(filp->f_op != &mqueue_file_operations)) 835 goto out_fput; 836 info = MQUEUE_I(inode); 837 audit_inode(NULL, inode); 838 839 if (unlikely(!(filp->f_mode & FMODE_WRITE))) 840 goto out_fput; 841 842 if (unlikely(msg_len > info->attr.mq_msgsize)) { 843 ret = -EMSGSIZE; 844 goto out_fput; 845 } 846 847 /* First try to allocate memory, before doing anything with 848 * existing queues. */ 849 msg_ptr = load_msg(u_msg_ptr, msg_len); 850 if (IS_ERR(msg_ptr)) { 851 ret = PTR_ERR(msg_ptr); 852 goto out_fput; 853 } 854 msg_ptr->m_ts = msg_len; 855 msg_ptr->m_type = msg_prio; 856 857 spin_lock(&info->lock); 858 859 if (info->attr.mq_curmsgs == info->attr.mq_maxmsg) { 860 if (filp->f_flags & O_NONBLOCK) { 861 spin_unlock(&info->lock); 862 ret = -EAGAIN; 863 } else if (unlikely(timeout < 0)) { 864 spin_unlock(&info->lock); 865 ret = timeout; 866 } else { 867 wait.task = current; 868 wait.msg = (void *) msg_ptr; 869 wait.state = STATE_NONE; 870 ret = wq_sleep(info, SEND, timeout, &wait); 871 } 872 if (ret < 0) 873 free_msg(msg_ptr); 874 } else { 875 receiver = wq_get_first_waiter(info, RECV); 876 if (receiver) { 877 pipelined_send(info, msg_ptr, receiver); 878 } else { 879 /* adds message to the queue */ 880 msg_insert(msg_ptr, info); 881 __do_notify(info); 882 } 883 inode->i_atime = inode->i_mtime = inode->i_ctime = 884 CURRENT_TIME; 885 spin_unlock(&info->lock); 886 ret = 0; 887 } 888 out_fput: 889 fput(filp); 890 out: 891 return ret; 892 } 893 894 asmlinkage ssize_t sys_mq_timedreceive(mqd_t mqdes, char __user *u_msg_ptr, 895 size_t msg_len, unsigned int __user *u_msg_prio, 896 const struct timespec __user *u_abs_timeout) 897 { 898 long timeout; 899 ssize_t ret; 900 struct msg_msg *msg_ptr; 901 struct file *filp; 902 struct inode *inode; 903 struct mqueue_inode_info *info; 904 struct ext_wait_queue wait; 905 906 ret = audit_mq_timedreceive(mqdes, msg_len, u_msg_prio, u_abs_timeout); 907 if (ret != 0) 908 return ret; 909 910 timeout = prepare_timeout(u_abs_timeout); 911 912 ret = -EBADF; 913 filp = fget(mqdes); 914 if (unlikely(!filp)) 915 goto out; 916 917 inode = filp->f_path.dentry->d_inode; 918 if (unlikely(filp->f_op != &mqueue_file_operations)) 919 goto out_fput; 920 info = MQUEUE_I(inode); 921 audit_inode(NULL, inode); 922 923 if (unlikely(!(filp->f_mode & FMODE_READ))) 924 goto out_fput; 925 926 /* checks if buffer is big enough */ 927 if (unlikely(msg_len < info->attr.mq_msgsize)) { 928 ret = -EMSGSIZE; 929 goto out_fput; 930 } 931 932 spin_lock(&info->lock); 933 if (info->attr.mq_curmsgs == 0) { 934 if (filp->f_flags & O_NONBLOCK) { 935 spin_unlock(&info->lock); 936 ret = -EAGAIN; 937 msg_ptr = NULL; 938 } else if (unlikely(timeout < 0)) { 939 spin_unlock(&info->lock); 940 ret = timeout; 941 msg_ptr = NULL; 942 } else { 943 wait.task = current; 944 wait.state = STATE_NONE; 945 ret = wq_sleep(info, RECV, timeout, &wait); 946 msg_ptr = wait.msg; 947 } 948 } else { 949 msg_ptr = msg_get(info); 950 951 inode->i_atime = inode->i_mtime = inode->i_ctime = 952 CURRENT_TIME; 953 954 /* There is now free space in queue. */ 955 pipelined_receive(info); 956 spin_unlock(&info->lock); 957 ret = 0; 958 } 959 if (ret == 0) { 960 ret = msg_ptr->m_ts; 961 962 if ((u_msg_prio && put_user(msg_ptr->m_type, u_msg_prio)) || 963 store_msg(u_msg_ptr, msg_ptr, msg_ptr->m_ts)) { 964 ret = -EFAULT; 965 } 966 free_msg(msg_ptr); 967 } 968 out_fput: 969 fput(filp); 970 out: 971 return ret; 972 } 973 974 /* 975 * Notes: the case when user wants us to deregister (with NULL as pointer) 976 * and he isn't currently owner of notification, will be silently discarded. 977 * It isn't explicitly defined in the POSIX. 978 */ 979 asmlinkage long sys_mq_notify(mqd_t mqdes, 980 const struct sigevent __user *u_notification) 981 { 982 int ret; 983 struct file *filp; 984 struct sock *sock; 985 struct inode *inode; 986 struct sigevent notification; 987 struct mqueue_inode_info *info; 988 struct sk_buff *nc; 989 990 ret = audit_mq_notify(mqdes, u_notification); 991 if (ret != 0) 992 return ret; 993 994 nc = NULL; 995 sock = NULL; 996 if (u_notification != NULL) { 997 if (copy_from_user(¬ification, u_notification, 998 sizeof(struct sigevent))) 999 return -EFAULT; 1000 1001 if (unlikely(notification.sigev_notify != SIGEV_NONE && 1002 notification.sigev_notify != SIGEV_SIGNAL && 1003 notification.sigev_notify != SIGEV_THREAD)) 1004 return -EINVAL; 1005 if (notification.sigev_notify == SIGEV_SIGNAL && 1006 !valid_signal(notification.sigev_signo)) { 1007 return -EINVAL; 1008 } 1009 if (notification.sigev_notify == SIGEV_THREAD) { 1010 /* create the notify skb */ 1011 nc = alloc_skb(NOTIFY_COOKIE_LEN, GFP_KERNEL); 1012 ret = -ENOMEM; 1013 if (!nc) 1014 goto out; 1015 ret = -EFAULT; 1016 if (copy_from_user(nc->data, 1017 notification.sigev_value.sival_ptr, 1018 NOTIFY_COOKIE_LEN)) { 1019 goto out; 1020 } 1021 1022 /* TODO: add a header? */ 1023 skb_put(nc, NOTIFY_COOKIE_LEN); 1024 /* and attach it to the socket */ 1025 retry: 1026 filp = fget(notification.sigev_signo); 1027 ret = -EBADF; 1028 if (!filp) 1029 goto out; 1030 sock = netlink_getsockbyfilp(filp); 1031 fput(filp); 1032 if (IS_ERR(sock)) { 1033 ret = PTR_ERR(sock); 1034 sock = NULL; 1035 goto out; 1036 } 1037 1038 ret = netlink_attachskb(sock, nc, 0, 1039 MAX_SCHEDULE_TIMEOUT, NULL); 1040 if (ret == 1) 1041 goto retry; 1042 if (ret) { 1043 sock = NULL; 1044 nc = NULL; 1045 goto out; 1046 } 1047 } 1048 } 1049 1050 ret = -EBADF; 1051 filp = fget(mqdes); 1052 if (!filp) 1053 goto out; 1054 1055 inode = filp->f_path.dentry->d_inode; 1056 if (unlikely(filp->f_op != &mqueue_file_operations)) 1057 goto out_fput; 1058 info = MQUEUE_I(inode); 1059 1060 ret = 0; 1061 spin_lock(&info->lock); 1062 if (u_notification == NULL) { 1063 if (info->notify_owner == task_tgid(current)) { 1064 remove_notification(info); 1065 inode->i_atime = inode->i_ctime = CURRENT_TIME; 1066 } 1067 } else if (info->notify_owner != NULL) { 1068 ret = -EBUSY; 1069 } else { 1070 switch (notification.sigev_notify) { 1071 case SIGEV_NONE: 1072 info->notify.sigev_notify = SIGEV_NONE; 1073 break; 1074 case SIGEV_THREAD: 1075 info->notify_sock = sock; 1076 info->notify_cookie = nc; 1077 sock = NULL; 1078 nc = NULL; 1079 info->notify.sigev_notify = SIGEV_THREAD; 1080 break; 1081 case SIGEV_SIGNAL: 1082 info->notify.sigev_signo = notification.sigev_signo; 1083 info->notify.sigev_value = notification.sigev_value; 1084 info->notify.sigev_notify = SIGEV_SIGNAL; 1085 break; 1086 } 1087 1088 info->notify_owner = get_pid(task_tgid(current)); 1089 inode->i_atime = inode->i_ctime = CURRENT_TIME; 1090 } 1091 spin_unlock(&info->lock); 1092 out_fput: 1093 fput(filp); 1094 out: 1095 if (sock) { 1096 netlink_detachskb(sock, nc); 1097 } else if (nc) { 1098 dev_kfree_skb(nc); 1099 } 1100 return ret; 1101 } 1102 1103 asmlinkage long sys_mq_getsetattr(mqd_t mqdes, 1104 const struct mq_attr __user *u_mqstat, 1105 struct mq_attr __user *u_omqstat) 1106 { 1107 int ret; 1108 struct mq_attr mqstat, omqstat; 1109 struct file *filp; 1110 struct inode *inode; 1111 struct mqueue_inode_info *info; 1112 1113 if (u_mqstat != NULL) { 1114 if (copy_from_user(&mqstat, u_mqstat, sizeof(struct mq_attr))) 1115 return -EFAULT; 1116 if (mqstat.mq_flags & (~O_NONBLOCK)) 1117 return -EINVAL; 1118 } 1119 1120 ret = -EBADF; 1121 filp = fget(mqdes); 1122 if (!filp) 1123 goto out; 1124 1125 inode = filp->f_path.dentry->d_inode; 1126 if (unlikely(filp->f_op != &mqueue_file_operations)) 1127 goto out_fput; 1128 info = MQUEUE_I(inode); 1129 1130 spin_lock(&info->lock); 1131 1132 omqstat = info->attr; 1133 omqstat.mq_flags = filp->f_flags & O_NONBLOCK; 1134 if (u_mqstat) { 1135 ret = audit_mq_getsetattr(mqdes, &mqstat); 1136 if (ret != 0) 1137 goto out; 1138 if (mqstat.mq_flags & O_NONBLOCK) 1139 filp->f_flags |= O_NONBLOCK; 1140 else 1141 filp->f_flags &= ~O_NONBLOCK; 1142 1143 inode->i_atime = inode->i_ctime = CURRENT_TIME; 1144 } 1145 1146 spin_unlock(&info->lock); 1147 1148 ret = 0; 1149 if (u_omqstat != NULL && copy_to_user(u_omqstat, &omqstat, 1150 sizeof(struct mq_attr))) 1151 ret = -EFAULT; 1152 1153 out_fput: 1154 fput(filp); 1155 out: 1156 return ret; 1157 } 1158 1159 static const struct inode_operations mqueue_dir_inode_operations = { 1160 .lookup = simple_lookup, 1161 .create = mqueue_create, 1162 .unlink = mqueue_unlink, 1163 }; 1164 1165 static const struct file_operations mqueue_file_operations = { 1166 .flush = mqueue_flush_file, 1167 .poll = mqueue_poll_file, 1168 .read = mqueue_read_file, 1169 }; 1170 1171 static struct super_operations mqueue_super_ops = { 1172 .alloc_inode = mqueue_alloc_inode, 1173 .destroy_inode = mqueue_destroy_inode, 1174 .statfs = simple_statfs, 1175 .delete_inode = mqueue_delete_inode, 1176 .drop_inode = generic_delete_inode, 1177 }; 1178 1179 static struct file_system_type mqueue_fs_type = { 1180 .name = "mqueue", 1181 .get_sb = mqueue_get_sb, 1182 .kill_sb = kill_litter_super, 1183 }; 1184 1185 static int msg_max_limit_min = DFLT_MSGMAX; 1186 static int msg_max_limit_max = HARD_MSGMAX; 1187 1188 static int msg_maxsize_limit_min = DFLT_MSGSIZEMAX; 1189 static int msg_maxsize_limit_max = INT_MAX; 1190 1191 static ctl_table mq_sysctls[] = { 1192 { 1193 .procname = "queues_max", 1194 .data = &queues_max, 1195 .maxlen = sizeof(int), 1196 .mode = 0644, 1197 .proc_handler = &proc_dointvec, 1198 }, 1199 { 1200 .procname = "msg_max", 1201 .data = &msg_max, 1202 .maxlen = sizeof(int), 1203 .mode = 0644, 1204 .proc_handler = &proc_dointvec_minmax, 1205 .extra1 = &msg_max_limit_min, 1206 .extra2 = &msg_max_limit_max, 1207 }, 1208 { 1209 .procname = "msgsize_max", 1210 .data = &msgsize_max, 1211 .maxlen = sizeof(int), 1212 .mode = 0644, 1213 .proc_handler = &proc_dointvec_minmax, 1214 .extra1 = &msg_maxsize_limit_min, 1215 .extra2 = &msg_maxsize_limit_max, 1216 }, 1217 { .ctl_name = 0 } 1218 }; 1219 1220 static ctl_table mq_sysctl_dir[] = { 1221 { 1222 .procname = "mqueue", 1223 .mode = 0555, 1224 .child = mq_sysctls, 1225 }, 1226 { .ctl_name = 0 } 1227 }; 1228 1229 static ctl_table mq_sysctl_root[] = { 1230 { 1231 .ctl_name = CTL_FS, 1232 .procname = "fs", 1233 .mode = 0555, 1234 .child = mq_sysctl_dir, 1235 }, 1236 { .ctl_name = 0 } 1237 }; 1238 1239 static int __init init_mqueue_fs(void) 1240 { 1241 int error; 1242 1243 mqueue_inode_cachep = kmem_cache_create("mqueue_inode_cache", 1244 sizeof(struct mqueue_inode_info), 0, 1245 SLAB_HWCACHE_ALIGN, init_once); 1246 if (mqueue_inode_cachep == NULL) 1247 return -ENOMEM; 1248 1249 /* ignore failues - they are not fatal */ 1250 mq_sysctl_table = register_sysctl_table(mq_sysctl_root); 1251 1252 error = register_filesystem(&mqueue_fs_type); 1253 if (error) 1254 goto out_sysctl; 1255 1256 if (IS_ERR(mqueue_mnt = kern_mount(&mqueue_fs_type))) { 1257 error = PTR_ERR(mqueue_mnt); 1258 goto out_filesystem; 1259 } 1260 1261 /* internal initialization - not common for vfs */ 1262 queues_count = 0; 1263 spin_lock_init(&mq_lock); 1264 1265 return 0; 1266 1267 out_filesystem: 1268 unregister_filesystem(&mqueue_fs_type); 1269 out_sysctl: 1270 if (mq_sysctl_table) 1271 unregister_sysctl_table(mq_sysctl_table); 1272 kmem_cache_destroy(mqueue_inode_cachep); 1273 return error; 1274 } 1275 1276 __initcall(init_mqueue_fs); 1277