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 #include <linux/nsproxy.h> 33 #include <linux/pid.h> 34 35 #include <net/sock.h> 36 #include "util.h" 37 38 #define MQUEUE_MAGIC 0x19800202 39 #define DIRENT_SIZE 20 40 #define FILENT_SIZE 80 41 42 #define SEND 0 43 #define RECV 1 44 45 #define STATE_NONE 0 46 #define STATE_PENDING 1 47 #define STATE_READY 2 48 49 /* default values */ 50 #define DFLT_QUEUESMAX 256 /* max number of message queues */ 51 #define DFLT_MSGMAX 10 /* max number of messages in each queue */ 52 #define HARD_MSGMAX (131072/sizeof(void*)) 53 #define DFLT_MSGSIZEMAX 8192 /* max message size */ 54 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 struct pid* 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 const struct inode_operations mqueue_dir_inode_operations; 84 static const 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 struct kmem_cache *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_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 = NULL; 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 inc_nlink(inode); 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 int mqueue_get_sb(struct file_system_type *fs_type, 204 int flags, const char *dev_name, 205 void *data, struct vfsmount *mnt) 206 { 207 return get_sb_single(fs_type, flags, data, mqueue_fill_super, mnt); 208 } 209 210 static void init_once(struct kmem_cache *cachep, void *foo) 211 { 212 struct mqueue_inode_info *p = (struct mqueue_inode_info *) foo; 213 214 inode_init_once(&p->vfs_inode); 215 } 216 217 static struct inode *mqueue_alloc_inode(struct super_block *sb) 218 { 219 struct mqueue_inode_info *ei; 220 221 ei = kmem_cache_alloc(mqueue_inode_cachep, GFP_KERNEL); 222 if (!ei) 223 return NULL; 224 return &ei->vfs_inode; 225 } 226 227 static void mqueue_destroy_inode(struct inode *inode) 228 { 229 kmem_cache_free(mqueue_inode_cachep, MQUEUE_I(inode)); 230 } 231 232 static void mqueue_delete_inode(struct inode *inode) 233 { 234 struct mqueue_inode_info *info; 235 struct user_struct *user; 236 unsigned long mq_bytes; 237 int i; 238 239 if (S_ISDIR(inode->i_mode)) { 240 clear_inode(inode); 241 return; 242 } 243 info = MQUEUE_I(inode); 244 spin_lock(&info->lock); 245 for (i = 0; i < info->attr.mq_curmsgs; i++) 246 free_msg(info->messages[i]); 247 kfree(info->messages); 248 spin_unlock(&info->lock); 249 250 clear_inode(inode); 251 252 mq_bytes = (info->attr.mq_maxmsg * sizeof(struct msg_msg *) + 253 (info->attr.mq_maxmsg * info->attr.mq_msgsize)); 254 user = info->user; 255 if (user) { 256 spin_lock(&mq_lock); 257 user->mq_bytes -= mq_bytes; 258 queues_count--; 259 spin_unlock(&mq_lock); 260 free_uid(user); 261 } 262 } 263 264 static int mqueue_create(struct inode *dir, struct dentry *dentry, 265 int mode, struct nameidata *nd) 266 { 267 struct inode *inode; 268 struct mq_attr *attr = dentry->d_fsdata; 269 int error; 270 271 spin_lock(&mq_lock); 272 if (queues_count >= queues_max && !capable(CAP_SYS_RESOURCE)) { 273 error = -ENOSPC; 274 goto out_lock; 275 } 276 queues_count++; 277 spin_unlock(&mq_lock); 278 279 inode = mqueue_get_inode(dir->i_sb, mode, attr); 280 if (!inode) { 281 error = -ENOMEM; 282 spin_lock(&mq_lock); 283 queues_count--; 284 goto out_lock; 285 } 286 287 dir->i_size += DIRENT_SIZE; 288 dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME; 289 290 d_instantiate(dentry, inode); 291 dget(dentry); 292 return 0; 293 out_lock: 294 spin_unlock(&mq_lock); 295 return error; 296 } 297 298 static int mqueue_unlink(struct inode *dir, struct dentry *dentry) 299 { 300 struct inode *inode = dentry->d_inode; 301 302 dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME; 303 dir->i_size -= DIRENT_SIZE; 304 drop_nlink(inode); 305 dput(dentry); 306 return 0; 307 } 308 309 /* 310 * This is routine for system read from queue file. 311 * To avoid mess with doing here some sort of mq_receive we allow 312 * to read only queue size & notification info (the only values 313 * that are interesting from user point of view and aren't accessible 314 * through std routines) 315 */ 316 static ssize_t mqueue_read_file(struct file *filp, char __user *u_data, 317 size_t count, loff_t * off) 318 { 319 struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode); 320 char buffer[FILENT_SIZE]; 321 size_t slen; 322 loff_t o; 323 324 if (!count) 325 return 0; 326 327 spin_lock(&info->lock); 328 snprintf(buffer, sizeof(buffer), 329 "QSIZE:%-10lu NOTIFY:%-5d SIGNO:%-5d NOTIFY_PID:%-6d\n", 330 info->qsize, 331 info->notify_owner ? info->notify.sigev_notify : 0, 332 (info->notify_owner && 333 info->notify.sigev_notify == SIGEV_SIGNAL) ? 334 info->notify.sigev_signo : 0, 335 pid_vnr(info->notify_owner)); 336 spin_unlock(&info->lock); 337 buffer[sizeof(buffer)-1] = '\0'; 338 slen = strlen(buffer)+1; 339 340 o = *off; 341 if (o > slen) 342 return 0; 343 344 if (o + count > slen) 345 count = slen - o; 346 347 if (copy_to_user(u_data, buffer + o, count)) 348 return -EFAULT; 349 350 *off = o + count; 351 filp->f_path.dentry->d_inode->i_atime = filp->f_path.dentry->d_inode->i_ctime = CURRENT_TIME; 352 return count; 353 } 354 355 static int mqueue_flush_file(struct file *filp, fl_owner_t id) 356 { 357 struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode); 358 359 spin_lock(&info->lock); 360 if (task_tgid(current) == info->notify_owner) 361 remove_notification(info); 362 363 spin_unlock(&info->lock); 364 return 0; 365 } 366 367 static unsigned int mqueue_poll_file(struct file *filp, struct poll_table_struct *poll_tab) 368 { 369 struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode); 370 int retval = 0; 371 372 poll_wait(filp, &info->wait_q, poll_tab); 373 374 spin_lock(&info->lock); 375 if (info->attr.mq_curmsgs) 376 retval = POLLIN | POLLRDNORM; 377 378 if (info->attr.mq_curmsgs < info->attr.mq_maxmsg) 379 retval |= POLLOUT | POLLWRNORM; 380 spin_unlock(&info->lock); 381 382 return retval; 383 } 384 385 /* Adds current to info->e_wait_q[sr] before element with smaller prio */ 386 static void wq_add(struct mqueue_inode_info *info, int sr, 387 struct ext_wait_queue *ewp) 388 { 389 struct ext_wait_queue *walk; 390 391 ewp->task = current; 392 393 list_for_each_entry(walk, &info->e_wait_q[sr].list, list) { 394 if (walk->task->static_prio <= current->static_prio) { 395 list_add_tail(&ewp->list, &walk->list); 396 return; 397 } 398 } 399 list_add_tail(&ewp->list, &info->e_wait_q[sr].list); 400 } 401 402 /* 403 * Puts current task to sleep. Caller must hold queue lock. After return 404 * lock isn't held. 405 * sr: SEND or RECV 406 */ 407 static int wq_sleep(struct mqueue_inode_info *info, int sr, 408 long timeout, struct ext_wait_queue *ewp) 409 { 410 int retval; 411 signed long time; 412 413 wq_add(info, sr, ewp); 414 415 for (;;) { 416 set_current_state(TASK_INTERRUPTIBLE); 417 418 spin_unlock(&info->lock); 419 time = schedule_timeout(timeout); 420 421 while (ewp->state == STATE_PENDING) 422 cpu_relax(); 423 424 if (ewp->state == STATE_READY) { 425 retval = 0; 426 goto out; 427 } 428 spin_lock(&info->lock); 429 if (ewp->state == STATE_READY) { 430 retval = 0; 431 goto out_unlock; 432 } 433 if (signal_pending(current)) { 434 retval = -ERESTARTSYS; 435 break; 436 } 437 if (time == 0) { 438 retval = -ETIMEDOUT; 439 break; 440 } 441 } 442 list_del(&ewp->list); 443 out_unlock: 444 spin_unlock(&info->lock); 445 out: 446 return retval; 447 } 448 449 /* 450 * Returns waiting task that should be serviced first or NULL if none exists 451 */ 452 static struct ext_wait_queue *wq_get_first_waiter( 453 struct mqueue_inode_info *info, int sr) 454 { 455 struct list_head *ptr; 456 457 ptr = info->e_wait_q[sr].list.prev; 458 if (ptr == &info->e_wait_q[sr].list) 459 return NULL; 460 return list_entry(ptr, struct ext_wait_queue, list); 461 } 462 463 /* Auxiliary functions to manipulate messages' list */ 464 static void msg_insert(struct msg_msg *ptr, struct mqueue_inode_info *info) 465 { 466 int k; 467 468 k = info->attr.mq_curmsgs - 1; 469 while (k >= 0 && info->messages[k]->m_type >= ptr->m_type) { 470 info->messages[k + 1] = info->messages[k]; 471 k--; 472 } 473 info->attr.mq_curmsgs++; 474 info->qsize += ptr->m_ts; 475 info->messages[k + 1] = ptr; 476 } 477 478 static inline struct msg_msg *msg_get(struct mqueue_inode_info *info) 479 { 480 info->qsize -= info->messages[--info->attr.mq_curmsgs]->m_ts; 481 return info->messages[info->attr.mq_curmsgs]; 482 } 483 484 static inline void set_cookie(struct sk_buff *skb, char code) 485 { 486 ((char*)skb->data)[NOTIFY_COOKIE_LEN-1] = code; 487 } 488 489 /* 490 * The next function is only to split too long sys_mq_timedsend 491 */ 492 static void __do_notify(struct mqueue_inode_info *info) 493 { 494 /* notification 495 * invoked when there is registered process and there isn't process 496 * waiting synchronously for message AND state of queue changed from 497 * empty to not empty. Here we are sure that no one is waiting 498 * synchronously. */ 499 if (info->notify_owner && 500 info->attr.mq_curmsgs == 1) { 501 struct siginfo sig_i; 502 switch (info->notify.sigev_notify) { 503 case SIGEV_NONE: 504 break; 505 case SIGEV_SIGNAL: 506 /* sends signal */ 507 508 sig_i.si_signo = info->notify.sigev_signo; 509 sig_i.si_errno = 0; 510 sig_i.si_code = SI_MESGQ; 511 sig_i.si_value = info->notify.sigev_value; 512 sig_i.si_pid = task_tgid_vnr(current); 513 sig_i.si_uid = current->uid; 514 515 kill_pid_info(info->notify.sigev_signo, 516 &sig_i, info->notify_owner); 517 break; 518 case SIGEV_THREAD: 519 set_cookie(info->notify_cookie, NOTIFY_WOKENUP); 520 netlink_sendskb(info->notify_sock, info->notify_cookie); 521 break; 522 } 523 /* after notification unregisters process */ 524 put_pid(info->notify_owner); 525 info->notify_owner = NULL; 526 } 527 wake_up(&info->wait_q); 528 } 529 530 static long prepare_timeout(const struct timespec __user *u_arg) 531 { 532 struct timespec ts, nowts; 533 long timeout; 534 535 if (u_arg) { 536 if (unlikely(copy_from_user(&ts, u_arg, 537 sizeof(struct timespec)))) 538 return -EFAULT; 539 540 if (unlikely(ts.tv_nsec < 0 || ts.tv_sec < 0 541 || ts.tv_nsec >= NSEC_PER_SEC)) 542 return -EINVAL; 543 nowts = CURRENT_TIME; 544 /* first subtract as jiffies can't be too big */ 545 ts.tv_sec -= nowts.tv_sec; 546 if (ts.tv_nsec < nowts.tv_nsec) { 547 ts.tv_nsec += NSEC_PER_SEC; 548 ts.tv_sec--; 549 } 550 ts.tv_nsec -= nowts.tv_nsec; 551 if (ts.tv_sec < 0) 552 return 0; 553 554 timeout = timespec_to_jiffies(&ts) + 1; 555 } else 556 return MAX_SCHEDULE_TIMEOUT; 557 558 return timeout; 559 } 560 561 static void remove_notification(struct mqueue_inode_info *info) 562 { 563 if (info->notify_owner != NULL && 564 info->notify.sigev_notify == SIGEV_THREAD) { 565 set_cookie(info->notify_cookie, NOTIFY_REMOVED); 566 netlink_sendskb(info->notify_sock, info->notify_cookie); 567 } 568 put_pid(info->notify_owner); 569 info->notify_owner = NULL; 570 } 571 572 static int mq_attr_ok(struct mq_attr *attr) 573 { 574 if (attr->mq_maxmsg <= 0 || attr->mq_msgsize <= 0) 575 return 0; 576 if (capable(CAP_SYS_RESOURCE)) { 577 if (attr->mq_maxmsg > HARD_MSGMAX) 578 return 0; 579 } else { 580 if (attr->mq_maxmsg > msg_max || 581 attr->mq_msgsize > msgsize_max) 582 return 0; 583 } 584 /* check for overflow */ 585 if (attr->mq_msgsize > ULONG_MAX/attr->mq_maxmsg) 586 return 0; 587 if ((unsigned long)(attr->mq_maxmsg * attr->mq_msgsize) + 588 (attr->mq_maxmsg * sizeof (struct msg_msg *)) < 589 (unsigned long)(attr->mq_maxmsg * attr->mq_msgsize)) 590 return 0; 591 return 1; 592 } 593 594 /* 595 * Invoked when creating a new queue via sys_mq_open 596 */ 597 static struct file *do_create(struct dentry *dir, struct dentry *dentry, 598 int oflag, mode_t mode, struct mq_attr __user *u_attr) 599 { 600 struct mq_attr attr; 601 int ret; 602 603 if (u_attr) { 604 ret = -EFAULT; 605 if (copy_from_user(&attr, u_attr, sizeof(attr))) 606 goto out; 607 ret = -EINVAL; 608 if (!mq_attr_ok(&attr)) 609 goto out; 610 /* store for use during create */ 611 dentry->d_fsdata = &attr; 612 } 613 614 mode &= ~current->fs->umask; 615 ret = vfs_create(dir->d_inode, dentry, mode, NULL); 616 dentry->d_fsdata = NULL; 617 if (ret) 618 goto out; 619 620 return dentry_open(dentry, mqueue_mnt, oflag); 621 622 out: 623 dput(dentry); 624 mntput(mqueue_mnt); 625 return ERR_PTR(ret); 626 } 627 628 /* Opens existing queue */ 629 static struct file *do_open(struct dentry *dentry, int oflag) 630 { 631 static int oflag2acc[O_ACCMODE] = { MAY_READ, MAY_WRITE, 632 MAY_READ | MAY_WRITE }; 633 634 if ((oflag & O_ACCMODE) == (O_RDWR | O_WRONLY)) { 635 dput(dentry); 636 mntput(mqueue_mnt); 637 return ERR_PTR(-EINVAL); 638 } 639 640 if (permission(dentry->d_inode, oflag2acc[oflag & O_ACCMODE], NULL)) { 641 dput(dentry); 642 mntput(mqueue_mnt); 643 return ERR_PTR(-EACCES); 644 } 645 646 return dentry_open(dentry, mqueue_mnt, oflag); 647 } 648 649 asmlinkage long sys_mq_open(const char __user *u_name, int oflag, mode_t mode, 650 struct mq_attr __user *u_attr) 651 { 652 struct dentry *dentry; 653 struct file *filp; 654 char *name; 655 int fd, error; 656 657 error = audit_mq_open(oflag, mode, u_attr); 658 if (error != 0) 659 return error; 660 661 if (IS_ERR(name = getname(u_name))) 662 return PTR_ERR(name); 663 664 fd = get_unused_fd(); 665 if (fd < 0) 666 goto out_putname; 667 668 mutex_lock(&mqueue_mnt->mnt_root->d_inode->i_mutex); 669 dentry = lookup_one_len(name, mqueue_mnt->mnt_root, strlen(name)); 670 if (IS_ERR(dentry)) { 671 error = PTR_ERR(dentry); 672 goto out_err; 673 } 674 mntget(mqueue_mnt); 675 676 if (oflag & O_CREAT) { 677 if (dentry->d_inode) { /* entry already exists */ 678 audit_inode(name, dentry); 679 error = -EEXIST; 680 if (oflag & O_EXCL) 681 goto out; 682 filp = do_open(dentry, oflag); 683 } else { 684 filp = do_create(mqueue_mnt->mnt_root, dentry, 685 oflag, mode, u_attr); 686 } 687 } else { 688 error = -ENOENT; 689 if (!dentry->d_inode) 690 goto out; 691 audit_inode(name, dentry); 692 filp = do_open(dentry, oflag); 693 } 694 695 if (IS_ERR(filp)) { 696 error = PTR_ERR(filp); 697 goto out_putfd; 698 } 699 700 set_close_on_exec(fd, 1); 701 fd_install(fd, filp); 702 goto out_upsem; 703 704 out: 705 dput(dentry); 706 mntput(mqueue_mnt); 707 out_putfd: 708 put_unused_fd(fd); 709 out_err: 710 fd = error; 711 out_upsem: 712 mutex_unlock(&mqueue_mnt->mnt_root->d_inode->i_mutex); 713 out_putname: 714 putname(name); 715 return fd; 716 } 717 718 asmlinkage long sys_mq_unlink(const char __user *u_name) 719 { 720 int err; 721 char *name; 722 struct dentry *dentry; 723 struct inode *inode = NULL; 724 725 name = getname(u_name); 726 if (IS_ERR(name)) 727 return PTR_ERR(name); 728 729 mutex_lock_nested(&mqueue_mnt->mnt_root->d_inode->i_mutex, 730 I_MUTEX_PARENT); 731 dentry = lookup_one_len(name, mqueue_mnt->mnt_root, strlen(name)); 732 if (IS_ERR(dentry)) { 733 err = PTR_ERR(dentry); 734 goto out_unlock; 735 } 736 737 if (!dentry->d_inode) { 738 err = -ENOENT; 739 goto out_err; 740 } 741 742 inode = dentry->d_inode; 743 if (inode) 744 atomic_inc(&inode->i_count); 745 746 err = vfs_unlink(dentry->d_parent->d_inode, dentry); 747 out_err: 748 dput(dentry); 749 750 out_unlock: 751 mutex_unlock(&mqueue_mnt->mnt_root->d_inode->i_mutex); 752 putname(name); 753 if (inode) 754 iput(inode); 755 756 return err; 757 } 758 759 /* Pipelined send and receive functions. 760 * 761 * If a receiver finds no waiting message, then it registers itself in the 762 * list of waiting receivers. A sender checks that list before adding the new 763 * message into the message array. If there is a waiting receiver, then it 764 * bypasses the message array and directly hands the message over to the 765 * receiver. 766 * The receiver accepts the message and returns without grabbing the queue 767 * spinlock. Therefore an intermediate STATE_PENDING state and memory barriers 768 * are necessary. The same algorithm is used for sysv semaphores, see 769 * ipc/sem.c for more details. 770 * 771 * The same algorithm is used for senders. 772 */ 773 774 /* pipelined_send() - send a message directly to the task waiting in 775 * sys_mq_timedreceive() (without inserting message into a queue). 776 */ 777 static inline void pipelined_send(struct mqueue_inode_info *info, 778 struct msg_msg *message, 779 struct ext_wait_queue *receiver) 780 { 781 receiver->msg = message; 782 list_del(&receiver->list); 783 receiver->state = STATE_PENDING; 784 wake_up_process(receiver->task); 785 smp_wmb(); 786 receiver->state = STATE_READY; 787 } 788 789 /* pipelined_receive() - if there is task waiting in sys_mq_timedsend() 790 * gets its message and put to the queue (we have one free place for sure). */ 791 static inline void pipelined_receive(struct mqueue_inode_info *info) 792 { 793 struct ext_wait_queue *sender = wq_get_first_waiter(info, SEND); 794 795 if (!sender) { 796 /* for poll */ 797 wake_up_interruptible(&info->wait_q); 798 return; 799 } 800 msg_insert(sender->msg, info); 801 list_del(&sender->list); 802 sender->state = STATE_PENDING; 803 wake_up_process(sender->task); 804 smp_wmb(); 805 sender->state = STATE_READY; 806 } 807 808 asmlinkage long sys_mq_timedsend(mqd_t mqdes, const char __user *u_msg_ptr, 809 size_t msg_len, unsigned int msg_prio, 810 const struct timespec __user *u_abs_timeout) 811 { 812 struct file *filp; 813 struct inode *inode; 814 struct ext_wait_queue wait; 815 struct ext_wait_queue *receiver; 816 struct msg_msg *msg_ptr; 817 struct mqueue_inode_info *info; 818 long timeout; 819 int ret; 820 821 ret = audit_mq_timedsend(mqdes, msg_len, msg_prio, u_abs_timeout); 822 if (ret != 0) 823 return ret; 824 825 if (unlikely(msg_prio >= (unsigned long) MQ_PRIO_MAX)) 826 return -EINVAL; 827 828 timeout = prepare_timeout(u_abs_timeout); 829 830 ret = -EBADF; 831 filp = fget(mqdes); 832 if (unlikely(!filp)) 833 goto out; 834 835 inode = filp->f_path.dentry->d_inode; 836 if (unlikely(filp->f_op != &mqueue_file_operations)) 837 goto out_fput; 838 info = MQUEUE_I(inode); 839 audit_inode(NULL, filp->f_path.dentry); 840 841 if (unlikely(!(filp->f_mode & FMODE_WRITE))) 842 goto out_fput; 843 844 if (unlikely(msg_len > info->attr.mq_msgsize)) { 845 ret = -EMSGSIZE; 846 goto out_fput; 847 } 848 849 /* First try to allocate memory, before doing anything with 850 * existing queues. */ 851 msg_ptr = load_msg(u_msg_ptr, msg_len); 852 if (IS_ERR(msg_ptr)) { 853 ret = PTR_ERR(msg_ptr); 854 goto out_fput; 855 } 856 msg_ptr->m_ts = msg_len; 857 msg_ptr->m_type = msg_prio; 858 859 spin_lock(&info->lock); 860 861 if (info->attr.mq_curmsgs == info->attr.mq_maxmsg) { 862 if (filp->f_flags & O_NONBLOCK) { 863 spin_unlock(&info->lock); 864 ret = -EAGAIN; 865 } else if (unlikely(timeout < 0)) { 866 spin_unlock(&info->lock); 867 ret = timeout; 868 } else { 869 wait.task = current; 870 wait.msg = (void *) msg_ptr; 871 wait.state = STATE_NONE; 872 ret = wq_sleep(info, SEND, timeout, &wait); 873 } 874 if (ret < 0) 875 free_msg(msg_ptr); 876 } else { 877 receiver = wq_get_first_waiter(info, RECV); 878 if (receiver) { 879 pipelined_send(info, msg_ptr, receiver); 880 } else { 881 /* adds message to the queue */ 882 msg_insert(msg_ptr, info); 883 __do_notify(info); 884 } 885 inode->i_atime = inode->i_mtime = inode->i_ctime = 886 CURRENT_TIME; 887 spin_unlock(&info->lock); 888 ret = 0; 889 } 890 out_fput: 891 fput(filp); 892 out: 893 return ret; 894 } 895 896 asmlinkage ssize_t sys_mq_timedreceive(mqd_t mqdes, char __user *u_msg_ptr, 897 size_t msg_len, unsigned int __user *u_msg_prio, 898 const struct timespec __user *u_abs_timeout) 899 { 900 long timeout; 901 ssize_t ret; 902 struct msg_msg *msg_ptr; 903 struct file *filp; 904 struct inode *inode; 905 struct mqueue_inode_info *info; 906 struct ext_wait_queue wait; 907 908 ret = audit_mq_timedreceive(mqdes, msg_len, u_msg_prio, u_abs_timeout); 909 if (ret != 0) 910 return ret; 911 912 timeout = prepare_timeout(u_abs_timeout); 913 914 ret = -EBADF; 915 filp = fget(mqdes); 916 if (unlikely(!filp)) 917 goto out; 918 919 inode = filp->f_path.dentry->d_inode; 920 if (unlikely(filp->f_op != &mqueue_file_operations)) 921 goto out_fput; 922 info = MQUEUE_I(inode); 923 audit_inode(NULL, filp->f_path.dentry); 924 925 if (unlikely(!(filp->f_mode & FMODE_READ))) 926 goto out_fput; 927 928 /* checks if buffer is big enough */ 929 if (unlikely(msg_len < info->attr.mq_msgsize)) { 930 ret = -EMSGSIZE; 931 goto out_fput; 932 } 933 934 spin_lock(&info->lock); 935 if (info->attr.mq_curmsgs == 0) { 936 if (filp->f_flags & O_NONBLOCK) { 937 spin_unlock(&info->lock); 938 ret = -EAGAIN; 939 msg_ptr = NULL; 940 } else if (unlikely(timeout < 0)) { 941 spin_unlock(&info->lock); 942 ret = timeout; 943 msg_ptr = NULL; 944 } else { 945 wait.task = current; 946 wait.state = STATE_NONE; 947 ret = wq_sleep(info, RECV, timeout, &wait); 948 msg_ptr = wait.msg; 949 } 950 } else { 951 msg_ptr = msg_get(info); 952 953 inode->i_atime = inode->i_mtime = inode->i_ctime = 954 CURRENT_TIME; 955 956 /* There is now free space in queue. */ 957 pipelined_receive(info); 958 spin_unlock(&info->lock); 959 ret = 0; 960 } 961 if (ret == 0) { 962 ret = msg_ptr->m_ts; 963 964 if ((u_msg_prio && put_user(msg_ptr->m_type, u_msg_prio)) || 965 store_msg(u_msg_ptr, msg_ptr, msg_ptr->m_ts)) { 966 ret = -EFAULT; 967 } 968 free_msg(msg_ptr); 969 } 970 out_fput: 971 fput(filp); 972 out: 973 return ret; 974 } 975 976 /* 977 * Notes: the case when user wants us to deregister (with NULL as pointer) 978 * and he isn't currently owner of notification, will be silently discarded. 979 * It isn't explicitly defined in the POSIX. 980 */ 981 asmlinkage long sys_mq_notify(mqd_t mqdes, 982 const struct sigevent __user *u_notification) 983 { 984 int ret; 985 struct file *filp; 986 struct sock *sock; 987 struct inode *inode; 988 struct sigevent notification; 989 struct mqueue_inode_info *info; 990 struct sk_buff *nc; 991 992 ret = audit_mq_notify(mqdes, u_notification); 993 if (ret != 0) 994 return ret; 995 996 nc = NULL; 997 sock = NULL; 998 if (u_notification != NULL) { 999 if (copy_from_user(¬ification, u_notification, 1000 sizeof(struct sigevent))) 1001 return -EFAULT; 1002 1003 if (unlikely(notification.sigev_notify != SIGEV_NONE && 1004 notification.sigev_notify != SIGEV_SIGNAL && 1005 notification.sigev_notify != SIGEV_THREAD)) 1006 return -EINVAL; 1007 if (notification.sigev_notify == SIGEV_SIGNAL && 1008 !valid_signal(notification.sigev_signo)) { 1009 return -EINVAL; 1010 } 1011 if (notification.sigev_notify == SIGEV_THREAD) { 1012 long timeo; 1013 1014 /* create the notify skb */ 1015 nc = alloc_skb(NOTIFY_COOKIE_LEN, GFP_KERNEL); 1016 ret = -ENOMEM; 1017 if (!nc) 1018 goto out; 1019 ret = -EFAULT; 1020 if (copy_from_user(nc->data, 1021 notification.sigev_value.sival_ptr, 1022 NOTIFY_COOKIE_LEN)) { 1023 goto out; 1024 } 1025 1026 /* TODO: add a header? */ 1027 skb_put(nc, NOTIFY_COOKIE_LEN); 1028 /* and attach it to the socket */ 1029 retry: 1030 filp = fget(notification.sigev_signo); 1031 ret = -EBADF; 1032 if (!filp) 1033 goto out; 1034 sock = netlink_getsockbyfilp(filp); 1035 fput(filp); 1036 if (IS_ERR(sock)) { 1037 ret = PTR_ERR(sock); 1038 sock = NULL; 1039 goto out; 1040 } 1041 1042 timeo = MAX_SCHEDULE_TIMEOUT; 1043 ret = netlink_attachskb(sock, nc, 0, &timeo, NULL); 1044 if (ret == 1) 1045 goto retry; 1046 if (ret) { 1047 sock = NULL; 1048 nc = NULL; 1049 goto out; 1050 } 1051 } 1052 } 1053 1054 ret = -EBADF; 1055 filp = fget(mqdes); 1056 if (!filp) 1057 goto out; 1058 1059 inode = filp->f_path.dentry->d_inode; 1060 if (unlikely(filp->f_op != &mqueue_file_operations)) 1061 goto out_fput; 1062 info = MQUEUE_I(inode); 1063 1064 ret = 0; 1065 spin_lock(&info->lock); 1066 if (u_notification == NULL) { 1067 if (info->notify_owner == task_tgid(current)) { 1068 remove_notification(info); 1069 inode->i_atime = inode->i_ctime = CURRENT_TIME; 1070 } 1071 } else if (info->notify_owner != NULL) { 1072 ret = -EBUSY; 1073 } else { 1074 switch (notification.sigev_notify) { 1075 case SIGEV_NONE: 1076 info->notify.sigev_notify = SIGEV_NONE; 1077 break; 1078 case SIGEV_THREAD: 1079 info->notify_sock = sock; 1080 info->notify_cookie = nc; 1081 sock = NULL; 1082 nc = NULL; 1083 info->notify.sigev_notify = SIGEV_THREAD; 1084 break; 1085 case SIGEV_SIGNAL: 1086 info->notify.sigev_signo = notification.sigev_signo; 1087 info->notify.sigev_value = notification.sigev_value; 1088 info->notify.sigev_notify = SIGEV_SIGNAL; 1089 break; 1090 } 1091 1092 info->notify_owner = get_pid(task_tgid(current)); 1093 inode->i_atime = inode->i_ctime = CURRENT_TIME; 1094 } 1095 spin_unlock(&info->lock); 1096 out_fput: 1097 fput(filp); 1098 out: 1099 if (sock) { 1100 netlink_detachskb(sock, nc); 1101 } else if (nc) { 1102 dev_kfree_skb(nc); 1103 } 1104 return ret; 1105 } 1106 1107 asmlinkage long sys_mq_getsetattr(mqd_t mqdes, 1108 const struct mq_attr __user *u_mqstat, 1109 struct mq_attr __user *u_omqstat) 1110 { 1111 int ret; 1112 struct mq_attr mqstat, omqstat; 1113 struct file *filp; 1114 struct inode *inode; 1115 struct mqueue_inode_info *info; 1116 1117 if (u_mqstat != NULL) { 1118 if (copy_from_user(&mqstat, u_mqstat, sizeof(struct mq_attr))) 1119 return -EFAULT; 1120 if (mqstat.mq_flags & (~O_NONBLOCK)) 1121 return -EINVAL; 1122 } 1123 1124 ret = -EBADF; 1125 filp = fget(mqdes); 1126 if (!filp) 1127 goto out; 1128 1129 inode = filp->f_path.dentry->d_inode; 1130 if (unlikely(filp->f_op != &mqueue_file_operations)) 1131 goto out_fput; 1132 info = MQUEUE_I(inode); 1133 1134 spin_lock(&info->lock); 1135 1136 omqstat = info->attr; 1137 omqstat.mq_flags = filp->f_flags & O_NONBLOCK; 1138 if (u_mqstat) { 1139 ret = audit_mq_getsetattr(mqdes, &mqstat); 1140 if (ret != 0) { 1141 spin_unlock(&info->lock); 1142 goto out_fput; 1143 } 1144 if (mqstat.mq_flags & O_NONBLOCK) 1145 filp->f_flags |= O_NONBLOCK; 1146 else 1147 filp->f_flags &= ~O_NONBLOCK; 1148 1149 inode->i_atime = inode->i_ctime = CURRENT_TIME; 1150 } 1151 1152 spin_unlock(&info->lock); 1153 1154 ret = 0; 1155 if (u_omqstat != NULL && copy_to_user(u_omqstat, &omqstat, 1156 sizeof(struct mq_attr))) 1157 ret = -EFAULT; 1158 1159 out_fput: 1160 fput(filp); 1161 out: 1162 return ret; 1163 } 1164 1165 static const struct inode_operations mqueue_dir_inode_operations = { 1166 .lookup = simple_lookup, 1167 .create = mqueue_create, 1168 .unlink = mqueue_unlink, 1169 }; 1170 1171 static const struct file_operations mqueue_file_operations = { 1172 .flush = mqueue_flush_file, 1173 .poll = mqueue_poll_file, 1174 .read = mqueue_read_file, 1175 }; 1176 1177 static struct super_operations mqueue_super_ops = { 1178 .alloc_inode = mqueue_alloc_inode, 1179 .destroy_inode = mqueue_destroy_inode, 1180 .statfs = simple_statfs, 1181 .delete_inode = mqueue_delete_inode, 1182 .drop_inode = generic_delete_inode, 1183 }; 1184 1185 static struct file_system_type mqueue_fs_type = { 1186 .name = "mqueue", 1187 .get_sb = mqueue_get_sb, 1188 .kill_sb = kill_litter_super, 1189 }; 1190 1191 static int msg_max_limit_min = DFLT_MSGMAX; 1192 static int msg_max_limit_max = HARD_MSGMAX; 1193 1194 static int msg_maxsize_limit_min = DFLT_MSGSIZEMAX; 1195 static int msg_maxsize_limit_max = INT_MAX; 1196 1197 static ctl_table mq_sysctls[] = { 1198 { 1199 .procname = "queues_max", 1200 .data = &queues_max, 1201 .maxlen = sizeof(int), 1202 .mode = 0644, 1203 .proc_handler = &proc_dointvec, 1204 }, 1205 { 1206 .procname = "msg_max", 1207 .data = &msg_max, 1208 .maxlen = sizeof(int), 1209 .mode = 0644, 1210 .proc_handler = &proc_dointvec_minmax, 1211 .extra1 = &msg_max_limit_min, 1212 .extra2 = &msg_max_limit_max, 1213 }, 1214 { 1215 .procname = "msgsize_max", 1216 .data = &msgsize_max, 1217 .maxlen = sizeof(int), 1218 .mode = 0644, 1219 .proc_handler = &proc_dointvec_minmax, 1220 .extra1 = &msg_maxsize_limit_min, 1221 .extra2 = &msg_maxsize_limit_max, 1222 }, 1223 { .ctl_name = 0 } 1224 }; 1225 1226 static ctl_table mq_sysctl_dir[] = { 1227 { 1228 .procname = "mqueue", 1229 .mode = 0555, 1230 .child = mq_sysctls, 1231 }, 1232 { .ctl_name = 0 } 1233 }; 1234 1235 static ctl_table mq_sysctl_root[] = { 1236 { 1237 .ctl_name = CTL_FS, 1238 .procname = "fs", 1239 .mode = 0555, 1240 .child = mq_sysctl_dir, 1241 }, 1242 { .ctl_name = 0 } 1243 }; 1244 1245 static int __init init_mqueue_fs(void) 1246 { 1247 int error; 1248 1249 mqueue_inode_cachep = kmem_cache_create("mqueue_inode_cache", 1250 sizeof(struct mqueue_inode_info), 0, 1251 SLAB_HWCACHE_ALIGN, init_once); 1252 if (mqueue_inode_cachep == NULL) 1253 return -ENOMEM; 1254 1255 /* ignore failues - they are not fatal */ 1256 mq_sysctl_table = register_sysctl_table(mq_sysctl_root); 1257 1258 error = register_filesystem(&mqueue_fs_type); 1259 if (error) 1260 goto out_sysctl; 1261 1262 if (IS_ERR(mqueue_mnt = kern_mount(&mqueue_fs_type))) { 1263 error = PTR_ERR(mqueue_mnt); 1264 goto out_filesystem; 1265 } 1266 1267 /* internal initialization - not common for vfs */ 1268 queues_count = 0; 1269 spin_lock_init(&mq_lock); 1270 1271 return 0; 1272 1273 out_filesystem: 1274 unregister_filesystem(&mqueue_fs_type); 1275 out_sysctl: 1276 if (mq_sysctl_table) 1277 unregister_sysctl_table(mq_sysctl_table); 1278 kmem_cache_destroy(mqueue_inode_cachep); 1279 return error; 1280 } 1281 1282 __initcall(init_mqueue_fs); 1283