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 /* used by sysctl */ 48 #define FS_MQUEUE 1 49 #define CTL_QUEUESMAX 2 50 #define CTL_MSGMAX 3 51 #define CTL_MSGSIZEMAX 4 52 53 /* default values */ 54 #define DFLT_QUEUESMAX 256 /* max number of message queues */ 55 #define DFLT_MSGMAX 10 /* max number of messages in each queue */ 56 #define HARD_MSGMAX (131072/sizeof(void*)) 57 #define DFLT_MSGSIZEMAX 8192 /* max message size */ 58 59 60 struct ext_wait_queue { /* queue of sleeping tasks */ 61 struct task_struct *task; 62 struct list_head list; 63 struct msg_msg *msg; /* ptr of loaded message */ 64 int state; /* one of STATE_* values */ 65 }; 66 67 struct mqueue_inode_info { 68 spinlock_t lock; 69 struct inode vfs_inode; 70 wait_queue_head_t wait_q; 71 72 struct msg_msg **messages; 73 struct mq_attr attr; 74 75 struct sigevent notify; 76 struct pid* notify_owner; 77 struct user_struct *user; /* user who created, for accounting */ 78 struct sock *notify_sock; 79 struct sk_buff *notify_cookie; 80 81 /* for tasks waiting for free space and messages, respectively */ 82 struct ext_wait_queue e_wait_q[2]; 83 84 unsigned long qsize; /* size of queue in memory (sum of all msgs) */ 85 }; 86 87 static const struct inode_operations mqueue_dir_inode_operations; 88 static const struct file_operations mqueue_file_operations; 89 static struct super_operations mqueue_super_ops; 90 static void remove_notification(struct mqueue_inode_info *info); 91 92 static spinlock_t mq_lock; 93 static struct kmem_cache *mqueue_inode_cachep; 94 static struct vfsmount *mqueue_mnt; 95 96 static unsigned int queues_count; 97 static unsigned int queues_max = DFLT_QUEUESMAX; 98 static unsigned int msg_max = DFLT_MSGMAX; 99 static unsigned int msgsize_max = DFLT_MSGSIZEMAX; 100 101 static struct ctl_table_header * mq_sysctl_table; 102 103 static inline struct mqueue_inode_info *MQUEUE_I(struct inode *inode) 104 { 105 return container_of(inode, struct mqueue_inode_info, vfs_inode); 106 } 107 108 static struct inode *mqueue_get_inode(struct super_block *sb, int mode, 109 struct mq_attr *attr) 110 { 111 struct inode *inode; 112 113 inode = new_inode(sb); 114 if (inode) { 115 inode->i_mode = mode; 116 inode->i_uid = current->fsuid; 117 inode->i_gid = current->fsgid; 118 inode->i_blocks = 0; 119 inode->i_mtime = inode->i_ctime = inode->i_atime = 120 CURRENT_TIME; 121 122 if (S_ISREG(mode)) { 123 struct mqueue_inode_info *info; 124 struct task_struct *p = current; 125 struct user_struct *u = p->user; 126 unsigned long mq_bytes, mq_msg_tblsz; 127 128 inode->i_fop = &mqueue_file_operations; 129 inode->i_size = FILENT_SIZE; 130 /* mqueue specific info */ 131 info = MQUEUE_I(inode); 132 spin_lock_init(&info->lock); 133 init_waitqueue_head(&info->wait_q); 134 INIT_LIST_HEAD(&info->e_wait_q[0].list); 135 INIT_LIST_HEAD(&info->e_wait_q[1].list); 136 info->messages = NULL; 137 info->notify_owner = NULL; 138 info->qsize = 0; 139 info->user = NULL; /* set when all is ok */ 140 memset(&info->attr, 0, sizeof(info->attr)); 141 info->attr.mq_maxmsg = DFLT_MSGMAX; 142 info->attr.mq_msgsize = DFLT_MSGSIZEMAX; 143 if (attr) { 144 info->attr.mq_maxmsg = attr->mq_maxmsg; 145 info->attr.mq_msgsize = attr->mq_msgsize; 146 } 147 mq_msg_tblsz = info->attr.mq_maxmsg * sizeof(struct msg_msg *); 148 mq_bytes = (mq_msg_tblsz + 149 (info->attr.mq_maxmsg * info->attr.mq_msgsize)); 150 151 spin_lock(&mq_lock); 152 if (u->mq_bytes + mq_bytes < u->mq_bytes || 153 u->mq_bytes + mq_bytes > 154 p->signal->rlim[RLIMIT_MSGQUEUE].rlim_cur) { 155 spin_unlock(&mq_lock); 156 goto out_inode; 157 } 158 u->mq_bytes += mq_bytes; 159 spin_unlock(&mq_lock); 160 161 info->messages = kmalloc(mq_msg_tblsz, GFP_KERNEL); 162 if (!info->messages) { 163 spin_lock(&mq_lock); 164 u->mq_bytes -= mq_bytes; 165 spin_unlock(&mq_lock); 166 goto out_inode; 167 } 168 /* all is ok */ 169 info->user = get_uid(u); 170 } else if (S_ISDIR(mode)) { 171 inc_nlink(inode); 172 /* Some things misbehave if size == 0 on a directory */ 173 inode->i_size = 2 * DIRENT_SIZE; 174 inode->i_op = &mqueue_dir_inode_operations; 175 inode->i_fop = &simple_dir_operations; 176 } 177 } 178 return inode; 179 out_inode: 180 make_bad_inode(inode); 181 iput(inode); 182 return NULL; 183 } 184 185 static int mqueue_fill_super(struct super_block *sb, void *data, int silent) 186 { 187 struct inode *inode; 188 189 sb->s_blocksize = PAGE_CACHE_SIZE; 190 sb->s_blocksize_bits = PAGE_CACHE_SHIFT; 191 sb->s_magic = MQUEUE_MAGIC; 192 sb->s_op = &mqueue_super_ops; 193 194 inode = mqueue_get_inode(sb, S_IFDIR | S_ISVTX | S_IRWXUGO, NULL); 195 if (!inode) 196 return -ENOMEM; 197 198 sb->s_root = d_alloc_root(inode); 199 if (!sb->s_root) { 200 iput(inode); 201 return -ENOMEM; 202 } 203 204 return 0; 205 } 206 207 static int mqueue_get_sb(struct file_system_type *fs_type, 208 int flags, const char *dev_name, 209 void *data, struct vfsmount *mnt) 210 { 211 return get_sb_single(fs_type, flags, data, mqueue_fill_super, mnt); 212 } 213 214 static void init_once(void *foo, struct kmem_cache * cachep, unsigned long flags) 215 { 216 struct mqueue_inode_info *p = (struct mqueue_inode_info *) foo; 217 218 if (flags & SLAB_CTOR_CONSTRUCTOR) 219 inode_init_once(&p->vfs_inode); 220 } 221 222 static struct inode *mqueue_alloc_inode(struct super_block *sb) 223 { 224 struct mqueue_inode_info *ei; 225 226 ei = kmem_cache_alloc(mqueue_inode_cachep, GFP_KERNEL); 227 if (!ei) 228 return NULL; 229 return &ei->vfs_inode; 230 } 231 232 static void mqueue_destroy_inode(struct inode *inode) 233 { 234 kmem_cache_free(mqueue_inode_cachep, MQUEUE_I(inode)); 235 } 236 237 static void mqueue_delete_inode(struct inode *inode) 238 { 239 struct mqueue_inode_info *info; 240 struct user_struct *user; 241 unsigned long mq_bytes; 242 int i; 243 244 if (S_ISDIR(inode->i_mode)) { 245 clear_inode(inode); 246 return; 247 } 248 info = MQUEUE_I(inode); 249 spin_lock(&info->lock); 250 for (i = 0; i < info->attr.mq_curmsgs; i++) 251 free_msg(info->messages[i]); 252 kfree(info->messages); 253 spin_unlock(&info->lock); 254 255 clear_inode(inode); 256 257 mq_bytes = (info->attr.mq_maxmsg * sizeof(struct msg_msg *) + 258 (info->attr.mq_maxmsg * info->attr.mq_msgsize)); 259 user = info->user; 260 if (user) { 261 spin_lock(&mq_lock); 262 user->mq_bytes -= mq_bytes; 263 queues_count--; 264 spin_unlock(&mq_lock); 265 free_uid(user); 266 } 267 } 268 269 static int mqueue_create(struct inode *dir, struct dentry *dentry, 270 int mode, struct nameidata *nd) 271 { 272 struct inode *inode; 273 struct mq_attr *attr = dentry->d_fsdata; 274 int error; 275 276 spin_lock(&mq_lock); 277 if (queues_count >= queues_max && !capable(CAP_SYS_RESOURCE)) { 278 error = -ENOSPC; 279 goto out_lock; 280 } 281 queues_count++; 282 spin_unlock(&mq_lock); 283 284 inode = mqueue_get_inode(dir->i_sb, mode, attr); 285 if (!inode) { 286 error = -ENOMEM; 287 spin_lock(&mq_lock); 288 queues_count--; 289 goto out_lock; 290 } 291 292 dir->i_size += DIRENT_SIZE; 293 dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME; 294 295 d_instantiate(dentry, inode); 296 dget(dentry); 297 return 0; 298 out_lock: 299 spin_unlock(&mq_lock); 300 return error; 301 } 302 303 static int mqueue_unlink(struct inode *dir, struct dentry *dentry) 304 { 305 struct inode *inode = dentry->d_inode; 306 307 dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME; 308 dir->i_size -= DIRENT_SIZE; 309 drop_nlink(inode); 310 dput(dentry); 311 return 0; 312 } 313 314 /* 315 * This is routine for system read from queue file. 316 * To avoid mess with doing here some sort of mq_receive we allow 317 * to read only queue size & notification info (the only values 318 * that are interesting from user point of view and aren't accessible 319 * through std routines) 320 */ 321 static ssize_t mqueue_read_file(struct file *filp, char __user *u_data, 322 size_t count, loff_t * off) 323 { 324 struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode); 325 char buffer[FILENT_SIZE]; 326 size_t slen; 327 loff_t o; 328 329 if (!count) 330 return 0; 331 332 spin_lock(&info->lock); 333 snprintf(buffer, sizeof(buffer), 334 "QSIZE:%-10lu NOTIFY:%-5d SIGNO:%-5d NOTIFY_PID:%-6d\n", 335 info->qsize, 336 info->notify_owner ? info->notify.sigev_notify : 0, 337 (info->notify_owner && 338 info->notify.sigev_notify == SIGEV_SIGNAL) ? 339 info->notify.sigev_signo : 0, 340 pid_nr(info->notify_owner)); 341 spin_unlock(&info->lock); 342 buffer[sizeof(buffer)-1] = '\0'; 343 slen = strlen(buffer)+1; 344 345 o = *off; 346 if (o > slen) 347 return 0; 348 349 if (o + count > slen) 350 count = slen - o; 351 352 if (copy_to_user(u_data, buffer + o, count)) 353 return -EFAULT; 354 355 *off = o + count; 356 filp->f_path.dentry->d_inode->i_atime = filp->f_path.dentry->d_inode->i_ctime = CURRENT_TIME; 357 return count; 358 } 359 360 static int mqueue_flush_file(struct file *filp, fl_owner_t id) 361 { 362 struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode); 363 364 spin_lock(&info->lock); 365 if (task_tgid(current) == info->notify_owner) 366 remove_notification(info); 367 368 spin_unlock(&info->lock); 369 return 0; 370 } 371 372 static unsigned int mqueue_poll_file(struct file *filp, struct poll_table_struct *poll_tab) 373 { 374 struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode); 375 int retval = 0; 376 377 poll_wait(filp, &info->wait_q, poll_tab); 378 379 spin_lock(&info->lock); 380 if (info->attr.mq_curmsgs) 381 retval = POLLIN | POLLRDNORM; 382 383 if (info->attr.mq_curmsgs < info->attr.mq_maxmsg) 384 retval |= POLLOUT | POLLWRNORM; 385 spin_unlock(&info->lock); 386 387 return retval; 388 } 389 390 /* Adds current to info->e_wait_q[sr] before element with smaller prio */ 391 static void wq_add(struct mqueue_inode_info *info, int sr, 392 struct ext_wait_queue *ewp) 393 { 394 struct ext_wait_queue *walk; 395 396 ewp->task = current; 397 398 list_for_each_entry(walk, &info->e_wait_q[sr].list, list) { 399 if (walk->task->static_prio <= current->static_prio) { 400 list_add_tail(&ewp->list, &walk->list); 401 return; 402 } 403 } 404 list_add_tail(&ewp->list, &info->e_wait_q[sr].list); 405 } 406 407 /* 408 * Puts current task to sleep. Caller must hold queue lock. After return 409 * lock isn't held. 410 * sr: SEND or RECV 411 */ 412 static int wq_sleep(struct mqueue_inode_info *info, int sr, 413 long timeout, struct ext_wait_queue *ewp) 414 { 415 int retval; 416 signed long time; 417 418 wq_add(info, sr, ewp); 419 420 for (;;) { 421 set_current_state(TASK_INTERRUPTIBLE); 422 423 spin_unlock(&info->lock); 424 time = schedule_timeout(timeout); 425 426 while (ewp->state == STATE_PENDING) 427 cpu_relax(); 428 429 if (ewp->state == STATE_READY) { 430 retval = 0; 431 goto out; 432 } 433 spin_lock(&info->lock); 434 if (ewp->state == STATE_READY) { 435 retval = 0; 436 goto out_unlock; 437 } 438 if (signal_pending(current)) { 439 retval = -ERESTARTSYS; 440 break; 441 } 442 if (time == 0) { 443 retval = -ETIMEDOUT; 444 break; 445 } 446 } 447 list_del(&ewp->list); 448 out_unlock: 449 spin_unlock(&info->lock); 450 out: 451 return retval; 452 } 453 454 /* 455 * Returns waiting task that should be serviced first or NULL if none exists 456 */ 457 static struct ext_wait_queue *wq_get_first_waiter( 458 struct mqueue_inode_info *info, int sr) 459 { 460 struct list_head *ptr; 461 462 ptr = info->e_wait_q[sr].list.prev; 463 if (ptr == &info->e_wait_q[sr].list) 464 return NULL; 465 return list_entry(ptr, struct ext_wait_queue, list); 466 } 467 468 /* Auxiliary functions to manipulate messages' list */ 469 static void msg_insert(struct msg_msg *ptr, struct mqueue_inode_info *info) 470 { 471 int k; 472 473 k = info->attr.mq_curmsgs - 1; 474 while (k >= 0 && info->messages[k]->m_type >= ptr->m_type) { 475 info->messages[k + 1] = info->messages[k]; 476 k--; 477 } 478 info->attr.mq_curmsgs++; 479 info->qsize += ptr->m_ts; 480 info->messages[k + 1] = ptr; 481 } 482 483 static inline struct msg_msg *msg_get(struct mqueue_inode_info *info) 484 { 485 info->qsize -= info->messages[--info->attr.mq_curmsgs]->m_ts; 486 return info->messages[info->attr.mq_curmsgs]; 487 } 488 489 static inline void set_cookie(struct sk_buff *skb, char code) 490 { 491 ((char*)skb->data)[NOTIFY_COOKIE_LEN-1] = code; 492 } 493 494 /* 495 * The next function is only to split too long sys_mq_timedsend 496 */ 497 static void __do_notify(struct mqueue_inode_info *info) 498 { 499 /* notification 500 * invoked when there is registered process and there isn't process 501 * waiting synchronously for message AND state of queue changed from 502 * empty to not empty. Here we are sure that no one is waiting 503 * synchronously. */ 504 if (info->notify_owner && 505 info->attr.mq_curmsgs == 1) { 506 struct siginfo sig_i; 507 switch (info->notify.sigev_notify) { 508 case SIGEV_NONE: 509 break; 510 case SIGEV_SIGNAL: 511 /* sends signal */ 512 513 sig_i.si_signo = info->notify.sigev_signo; 514 sig_i.si_errno = 0; 515 sig_i.si_code = SI_MESGQ; 516 sig_i.si_value = info->notify.sigev_value; 517 sig_i.si_pid = current->tgid; 518 sig_i.si_uid = current->uid; 519 520 kill_pid_info(info->notify.sigev_signo, 521 &sig_i, info->notify_owner); 522 break; 523 case SIGEV_THREAD: 524 set_cookie(info->notify_cookie, NOTIFY_WOKENUP); 525 netlink_sendskb(info->notify_sock, 526 info->notify_cookie, 0); 527 break; 528 } 529 /* after notification unregisters process */ 530 put_pid(info->notify_owner); 531 info->notify_owner = NULL; 532 } 533 wake_up(&info->wait_q); 534 } 535 536 static long prepare_timeout(const struct timespec __user *u_arg) 537 { 538 struct timespec ts, nowts; 539 long timeout; 540 541 if (u_arg) { 542 if (unlikely(copy_from_user(&ts, u_arg, 543 sizeof(struct timespec)))) 544 return -EFAULT; 545 546 if (unlikely(ts.tv_nsec < 0 || ts.tv_sec < 0 547 || ts.tv_nsec >= NSEC_PER_SEC)) 548 return -EINVAL; 549 nowts = CURRENT_TIME; 550 /* first subtract as jiffies can't be too big */ 551 ts.tv_sec -= nowts.tv_sec; 552 if (ts.tv_nsec < nowts.tv_nsec) { 553 ts.tv_nsec += NSEC_PER_SEC; 554 ts.tv_sec--; 555 } 556 ts.tv_nsec -= nowts.tv_nsec; 557 if (ts.tv_sec < 0) 558 return 0; 559 560 timeout = timespec_to_jiffies(&ts) + 1; 561 } else 562 return MAX_SCHEDULE_TIMEOUT; 563 564 return timeout; 565 } 566 567 static void remove_notification(struct mqueue_inode_info *info) 568 { 569 if (info->notify_owner != NULL && 570 info->notify.sigev_notify == SIGEV_THREAD) { 571 set_cookie(info->notify_cookie, NOTIFY_REMOVED); 572 netlink_sendskb(info->notify_sock, info->notify_cookie, 0); 573 } 574 put_pid(info->notify_owner); 575 info->notify_owner = NULL; 576 } 577 578 static int mq_attr_ok(struct mq_attr *attr) 579 { 580 if (attr->mq_maxmsg <= 0 || attr->mq_msgsize <= 0) 581 return 0; 582 if (capable(CAP_SYS_RESOURCE)) { 583 if (attr->mq_maxmsg > HARD_MSGMAX) 584 return 0; 585 } else { 586 if (attr->mq_maxmsg > msg_max || 587 attr->mq_msgsize > msgsize_max) 588 return 0; 589 } 590 /* check for overflow */ 591 if (attr->mq_msgsize > ULONG_MAX/attr->mq_maxmsg) 592 return 0; 593 if ((unsigned long)(attr->mq_maxmsg * attr->mq_msgsize) + 594 (attr->mq_maxmsg * sizeof (struct msg_msg *)) < 595 (unsigned long)(attr->mq_maxmsg * attr->mq_msgsize)) 596 return 0; 597 return 1; 598 } 599 600 /* 601 * Invoked when creating a new queue via sys_mq_open 602 */ 603 static struct file *do_create(struct dentry *dir, struct dentry *dentry, 604 int oflag, mode_t mode, struct mq_attr __user *u_attr) 605 { 606 struct mq_attr attr; 607 int ret; 608 609 if (u_attr) { 610 ret = -EFAULT; 611 if (copy_from_user(&attr, u_attr, sizeof(attr))) 612 goto out; 613 ret = -EINVAL; 614 if (!mq_attr_ok(&attr)) 615 goto out; 616 /* store for use during create */ 617 dentry->d_fsdata = &attr; 618 } 619 620 mode &= ~current->fs->umask; 621 ret = vfs_create(dir->d_inode, dentry, mode, NULL); 622 dentry->d_fsdata = NULL; 623 if (ret) 624 goto out; 625 626 return dentry_open(dentry, mqueue_mnt, oflag); 627 628 out: 629 dput(dentry); 630 mntput(mqueue_mnt); 631 return ERR_PTR(ret); 632 } 633 634 /* Opens existing queue */ 635 static struct file *do_open(struct dentry *dentry, int oflag) 636 { 637 static int oflag2acc[O_ACCMODE] = { MAY_READ, MAY_WRITE, 638 MAY_READ | MAY_WRITE }; 639 640 if ((oflag & O_ACCMODE) == (O_RDWR | O_WRONLY)) { 641 dput(dentry); 642 mntput(mqueue_mnt); 643 return ERR_PTR(-EINVAL); 644 } 645 646 if (permission(dentry->d_inode, oflag2acc[oflag & O_ACCMODE], NULL)) { 647 dput(dentry); 648 mntput(mqueue_mnt); 649 return ERR_PTR(-EACCES); 650 } 651 652 return dentry_open(dentry, mqueue_mnt, oflag); 653 } 654 655 asmlinkage long sys_mq_open(const char __user *u_name, int oflag, mode_t mode, 656 struct mq_attr __user *u_attr) 657 { 658 struct dentry *dentry; 659 struct file *filp; 660 char *name; 661 int fd, error; 662 663 error = audit_mq_open(oflag, mode, u_attr); 664 if (error != 0) 665 return error; 666 667 if (IS_ERR(name = getname(u_name))) 668 return PTR_ERR(name); 669 670 fd = get_unused_fd(); 671 if (fd < 0) 672 goto out_putname; 673 674 mutex_lock(&mqueue_mnt->mnt_root->d_inode->i_mutex); 675 dentry = lookup_one_len(name, mqueue_mnt->mnt_root, strlen(name)); 676 if (IS_ERR(dentry)) { 677 error = PTR_ERR(dentry); 678 goto out_err; 679 } 680 mntget(mqueue_mnt); 681 682 if (oflag & O_CREAT) { 683 if (dentry->d_inode) { /* entry already exists */ 684 audit_inode(name, dentry->d_inode); 685 error = -EEXIST; 686 if (oflag & O_EXCL) 687 goto out; 688 filp = do_open(dentry, oflag); 689 } else { 690 filp = do_create(mqueue_mnt->mnt_root, dentry, 691 oflag, mode, u_attr); 692 } 693 } else { 694 error = -ENOENT; 695 if (!dentry->d_inode) 696 goto out; 697 audit_inode(name, dentry->d_inode); 698 filp = do_open(dentry, oflag); 699 } 700 701 if (IS_ERR(filp)) { 702 error = PTR_ERR(filp); 703 goto out_putfd; 704 } 705 706 set_close_on_exec(fd, 1); 707 fd_install(fd, filp); 708 goto out_upsem; 709 710 out: 711 dput(dentry); 712 mntput(mqueue_mnt); 713 out_putfd: 714 put_unused_fd(fd); 715 out_err: 716 fd = error; 717 out_upsem: 718 mutex_unlock(&mqueue_mnt->mnt_root->d_inode->i_mutex); 719 out_putname: 720 putname(name); 721 return fd; 722 } 723 724 asmlinkage long sys_mq_unlink(const char __user *u_name) 725 { 726 int err; 727 char *name; 728 struct dentry *dentry; 729 struct inode *inode = NULL; 730 731 name = getname(u_name); 732 if (IS_ERR(name)) 733 return PTR_ERR(name); 734 735 mutex_lock_nested(&mqueue_mnt->mnt_root->d_inode->i_mutex, 736 I_MUTEX_PARENT); 737 dentry = lookup_one_len(name, mqueue_mnt->mnt_root, strlen(name)); 738 if (IS_ERR(dentry)) { 739 err = PTR_ERR(dentry); 740 goto out_unlock; 741 } 742 743 if (!dentry->d_inode) { 744 err = -ENOENT; 745 goto out_err; 746 } 747 748 inode = dentry->d_inode; 749 if (inode) 750 atomic_inc(&inode->i_count); 751 752 err = vfs_unlink(dentry->d_parent->d_inode, dentry); 753 out_err: 754 dput(dentry); 755 756 out_unlock: 757 mutex_unlock(&mqueue_mnt->mnt_root->d_inode->i_mutex); 758 putname(name); 759 if (inode) 760 iput(inode); 761 762 return err; 763 } 764 765 /* Pipelined send and receive functions. 766 * 767 * If a receiver finds no waiting message, then it registers itself in the 768 * list of waiting receivers. A sender checks that list before adding the new 769 * message into the message array. If there is a waiting receiver, then it 770 * bypasses the message array and directly hands the message over to the 771 * receiver. 772 * The receiver accepts the message and returns without grabbing the queue 773 * spinlock. Therefore an intermediate STATE_PENDING state and memory barriers 774 * are necessary. The same algorithm is used for sysv semaphores, see 775 * ipc/sem.c for more details. 776 * 777 * The same algorithm is used for senders. 778 */ 779 780 /* pipelined_send() - send a message directly to the task waiting in 781 * sys_mq_timedreceive() (without inserting message into a queue). 782 */ 783 static inline void pipelined_send(struct mqueue_inode_info *info, 784 struct msg_msg *message, 785 struct ext_wait_queue *receiver) 786 { 787 receiver->msg = message; 788 list_del(&receiver->list); 789 receiver->state = STATE_PENDING; 790 wake_up_process(receiver->task); 791 smp_wmb(); 792 receiver->state = STATE_READY; 793 } 794 795 /* pipelined_receive() - if there is task waiting in sys_mq_timedsend() 796 * gets its message and put to the queue (we have one free place for sure). */ 797 static inline void pipelined_receive(struct mqueue_inode_info *info) 798 { 799 struct ext_wait_queue *sender = wq_get_first_waiter(info, SEND); 800 801 if (!sender) { 802 /* for poll */ 803 wake_up_interruptible(&info->wait_q); 804 return; 805 } 806 msg_insert(sender->msg, info); 807 list_del(&sender->list); 808 sender->state = STATE_PENDING; 809 wake_up_process(sender->task); 810 smp_wmb(); 811 sender->state = STATE_READY; 812 } 813 814 asmlinkage long sys_mq_timedsend(mqd_t mqdes, const char __user *u_msg_ptr, 815 size_t msg_len, unsigned int msg_prio, 816 const struct timespec __user *u_abs_timeout) 817 { 818 struct file *filp; 819 struct inode *inode; 820 struct ext_wait_queue wait; 821 struct ext_wait_queue *receiver; 822 struct msg_msg *msg_ptr; 823 struct mqueue_inode_info *info; 824 long timeout; 825 int ret; 826 827 ret = audit_mq_timedsend(mqdes, msg_len, msg_prio, u_abs_timeout); 828 if (ret != 0) 829 return ret; 830 831 if (unlikely(msg_prio >= (unsigned long) MQ_PRIO_MAX)) 832 return -EINVAL; 833 834 timeout = prepare_timeout(u_abs_timeout); 835 836 ret = -EBADF; 837 filp = fget(mqdes); 838 if (unlikely(!filp)) 839 goto out; 840 841 inode = filp->f_path.dentry->d_inode; 842 if (unlikely(filp->f_op != &mqueue_file_operations)) 843 goto out_fput; 844 info = MQUEUE_I(inode); 845 audit_inode(NULL, inode); 846 847 if (unlikely(!(filp->f_mode & FMODE_WRITE))) 848 goto out_fput; 849 850 if (unlikely(msg_len > info->attr.mq_msgsize)) { 851 ret = -EMSGSIZE; 852 goto out_fput; 853 } 854 855 /* First try to allocate memory, before doing anything with 856 * existing queues. */ 857 msg_ptr = load_msg(u_msg_ptr, msg_len); 858 if (IS_ERR(msg_ptr)) { 859 ret = PTR_ERR(msg_ptr); 860 goto out_fput; 861 } 862 msg_ptr->m_ts = msg_len; 863 msg_ptr->m_type = msg_prio; 864 865 spin_lock(&info->lock); 866 867 if (info->attr.mq_curmsgs == info->attr.mq_maxmsg) { 868 if (filp->f_flags & O_NONBLOCK) { 869 spin_unlock(&info->lock); 870 ret = -EAGAIN; 871 } else if (unlikely(timeout < 0)) { 872 spin_unlock(&info->lock); 873 ret = timeout; 874 } else { 875 wait.task = current; 876 wait.msg = (void *) msg_ptr; 877 wait.state = STATE_NONE; 878 ret = wq_sleep(info, SEND, timeout, &wait); 879 } 880 if (ret < 0) 881 free_msg(msg_ptr); 882 } else { 883 receiver = wq_get_first_waiter(info, RECV); 884 if (receiver) { 885 pipelined_send(info, msg_ptr, receiver); 886 } else { 887 /* adds message to the queue */ 888 msg_insert(msg_ptr, info); 889 __do_notify(info); 890 } 891 inode->i_atime = inode->i_mtime = inode->i_ctime = 892 CURRENT_TIME; 893 spin_unlock(&info->lock); 894 ret = 0; 895 } 896 out_fput: 897 fput(filp); 898 out: 899 return ret; 900 } 901 902 asmlinkage ssize_t sys_mq_timedreceive(mqd_t mqdes, char __user *u_msg_ptr, 903 size_t msg_len, unsigned int __user *u_msg_prio, 904 const struct timespec __user *u_abs_timeout) 905 { 906 long timeout; 907 ssize_t ret; 908 struct msg_msg *msg_ptr; 909 struct file *filp; 910 struct inode *inode; 911 struct mqueue_inode_info *info; 912 struct ext_wait_queue wait; 913 914 ret = audit_mq_timedreceive(mqdes, msg_len, u_msg_prio, u_abs_timeout); 915 if (ret != 0) 916 return ret; 917 918 timeout = prepare_timeout(u_abs_timeout); 919 920 ret = -EBADF; 921 filp = fget(mqdes); 922 if (unlikely(!filp)) 923 goto out; 924 925 inode = filp->f_path.dentry->d_inode; 926 if (unlikely(filp->f_op != &mqueue_file_operations)) 927 goto out_fput; 928 info = MQUEUE_I(inode); 929 audit_inode(NULL, inode); 930 931 if (unlikely(!(filp->f_mode & FMODE_READ))) 932 goto out_fput; 933 934 /* checks if buffer is big enough */ 935 if (unlikely(msg_len < info->attr.mq_msgsize)) { 936 ret = -EMSGSIZE; 937 goto out_fput; 938 } 939 940 spin_lock(&info->lock); 941 if (info->attr.mq_curmsgs == 0) { 942 if (filp->f_flags & O_NONBLOCK) { 943 spin_unlock(&info->lock); 944 ret = -EAGAIN; 945 msg_ptr = NULL; 946 } else if (unlikely(timeout < 0)) { 947 spin_unlock(&info->lock); 948 ret = timeout; 949 msg_ptr = NULL; 950 } else { 951 wait.task = current; 952 wait.state = STATE_NONE; 953 ret = wq_sleep(info, RECV, timeout, &wait); 954 msg_ptr = wait.msg; 955 } 956 } else { 957 msg_ptr = msg_get(info); 958 959 inode->i_atime = inode->i_mtime = inode->i_ctime = 960 CURRENT_TIME; 961 962 /* There is now free space in queue. */ 963 pipelined_receive(info); 964 spin_unlock(&info->lock); 965 ret = 0; 966 } 967 if (ret == 0) { 968 ret = msg_ptr->m_ts; 969 970 if ((u_msg_prio && put_user(msg_ptr->m_type, u_msg_prio)) || 971 store_msg(u_msg_ptr, msg_ptr, msg_ptr->m_ts)) { 972 ret = -EFAULT; 973 } 974 free_msg(msg_ptr); 975 } 976 out_fput: 977 fput(filp); 978 out: 979 return ret; 980 } 981 982 /* 983 * Notes: the case when user wants us to deregister (with NULL as pointer) 984 * and he isn't currently owner of notification, will be silently discarded. 985 * It isn't explicitly defined in the POSIX. 986 */ 987 asmlinkage long sys_mq_notify(mqd_t mqdes, 988 const struct sigevent __user *u_notification) 989 { 990 int ret; 991 struct file *filp; 992 struct sock *sock; 993 struct inode *inode; 994 struct sigevent notification; 995 struct mqueue_inode_info *info; 996 struct sk_buff *nc; 997 998 ret = audit_mq_notify(mqdes, u_notification); 999 if (ret != 0) 1000 return ret; 1001 1002 nc = NULL; 1003 sock = NULL; 1004 if (u_notification != NULL) { 1005 if (copy_from_user(¬ification, u_notification, 1006 sizeof(struct sigevent))) 1007 return -EFAULT; 1008 1009 if (unlikely(notification.sigev_notify != SIGEV_NONE && 1010 notification.sigev_notify != SIGEV_SIGNAL && 1011 notification.sigev_notify != SIGEV_THREAD)) 1012 return -EINVAL; 1013 if (notification.sigev_notify == SIGEV_SIGNAL && 1014 !valid_signal(notification.sigev_signo)) { 1015 return -EINVAL; 1016 } 1017 if (notification.sigev_notify == SIGEV_THREAD) { 1018 /* create the notify skb */ 1019 nc = alloc_skb(NOTIFY_COOKIE_LEN, GFP_KERNEL); 1020 ret = -ENOMEM; 1021 if (!nc) 1022 goto out; 1023 ret = -EFAULT; 1024 if (copy_from_user(nc->data, 1025 notification.sigev_value.sival_ptr, 1026 NOTIFY_COOKIE_LEN)) { 1027 goto out; 1028 } 1029 1030 /* TODO: add a header? */ 1031 skb_put(nc, NOTIFY_COOKIE_LEN); 1032 /* and attach it to the socket */ 1033 retry: 1034 filp = fget(notification.sigev_signo); 1035 ret = -EBADF; 1036 if (!filp) 1037 goto out; 1038 sock = netlink_getsockbyfilp(filp); 1039 fput(filp); 1040 if (IS_ERR(sock)) { 1041 ret = PTR_ERR(sock); 1042 sock = NULL; 1043 goto out; 1044 } 1045 1046 ret = netlink_attachskb(sock, nc, 0, 1047 MAX_SCHEDULE_TIMEOUT, NULL); 1048 if (ret == 1) 1049 goto retry; 1050 if (ret) { 1051 sock = NULL; 1052 nc = NULL; 1053 goto out; 1054 } 1055 } 1056 } 1057 1058 ret = -EBADF; 1059 filp = fget(mqdes); 1060 if (!filp) 1061 goto out; 1062 1063 inode = filp->f_path.dentry->d_inode; 1064 if (unlikely(filp->f_op != &mqueue_file_operations)) 1065 goto out_fput; 1066 info = MQUEUE_I(inode); 1067 1068 ret = 0; 1069 spin_lock(&info->lock); 1070 if (u_notification == NULL) { 1071 if (info->notify_owner == task_tgid(current)) { 1072 remove_notification(info); 1073 inode->i_atime = inode->i_ctime = CURRENT_TIME; 1074 } 1075 } else if (info->notify_owner != NULL) { 1076 ret = -EBUSY; 1077 } else { 1078 switch (notification.sigev_notify) { 1079 case SIGEV_NONE: 1080 info->notify.sigev_notify = SIGEV_NONE; 1081 break; 1082 case SIGEV_THREAD: 1083 info->notify_sock = sock; 1084 info->notify_cookie = nc; 1085 sock = NULL; 1086 nc = NULL; 1087 info->notify.sigev_notify = SIGEV_THREAD; 1088 break; 1089 case SIGEV_SIGNAL: 1090 info->notify.sigev_signo = notification.sigev_signo; 1091 info->notify.sigev_value = notification.sigev_value; 1092 info->notify.sigev_notify = SIGEV_SIGNAL; 1093 break; 1094 } 1095 1096 info->notify_owner = get_pid(task_tgid(current)); 1097 inode->i_atime = inode->i_ctime = CURRENT_TIME; 1098 } 1099 spin_unlock(&info->lock); 1100 out_fput: 1101 fput(filp); 1102 out: 1103 if (sock) { 1104 netlink_detachskb(sock, nc); 1105 } else if (nc) { 1106 dev_kfree_skb(nc); 1107 } 1108 return ret; 1109 } 1110 1111 asmlinkage long sys_mq_getsetattr(mqd_t mqdes, 1112 const struct mq_attr __user *u_mqstat, 1113 struct mq_attr __user *u_omqstat) 1114 { 1115 int ret; 1116 struct mq_attr mqstat, omqstat; 1117 struct file *filp; 1118 struct inode *inode; 1119 struct mqueue_inode_info *info; 1120 1121 if (u_mqstat != NULL) { 1122 if (copy_from_user(&mqstat, u_mqstat, sizeof(struct mq_attr))) 1123 return -EFAULT; 1124 if (mqstat.mq_flags & (~O_NONBLOCK)) 1125 return -EINVAL; 1126 } 1127 1128 ret = -EBADF; 1129 filp = fget(mqdes); 1130 if (!filp) 1131 goto out; 1132 1133 inode = filp->f_path.dentry->d_inode; 1134 if (unlikely(filp->f_op != &mqueue_file_operations)) 1135 goto out_fput; 1136 info = MQUEUE_I(inode); 1137 1138 spin_lock(&info->lock); 1139 1140 omqstat = info->attr; 1141 omqstat.mq_flags = filp->f_flags & O_NONBLOCK; 1142 if (u_mqstat) { 1143 ret = audit_mq_getsetattr(mqdes, &mqstat); 1144 if (ret != 0) 1145 goto out; 1146 if (mqstat.mq_flags & O_NONBLOCK) 1147 filp->f_flags |= O_NONBLOCK; 1148 else 1149 filp->f_flags &= ~O_NONBLOCK; 1150 1151 inode->i_atime = inode->i_ctime = CURRENT_TIME; 1152 } 1153 1154 spin_unlock(&info->lock); 1155 1156 ret = 0; 1157 if (u_omqstat != NULL && copy_to_user(u_omqstat, &omqstat, 1158 sizeof(struct mq_attr))) 1159 ret = -EFAULT; 1160 1161 out_fput: 1162 fput(filp); 1163 out: 1164 return ret; 1165 } 1166 1167 static const struct inode_operations mqueue_dir_inode_operations = { 1168 .lookup = simple_lookup, 1169 .create = mqueue_create, 1170 .unlink = mqueue_unlink, 1171 }; 1172 1173 static const struct file_operations mqueue_file_operations = { 1174 .flush = mqueue_flush_file, 1175 .poll = mqueue_poll_file, 1176 .read = mqueue_read_file, 1177 }; 1178 1179 static struct super_operations mqueue_super_ops = { 1180 .alloc_inode = mqueue_alloc_inode, 1181 .destroy_inode = mqueue_destroy_inode, 1182 .statfs = simple_statfs, 1183 .delete_inode = mqueue_delete_inode, 1184 .drop_inode = generic_delete_inode, 1185 }; 1186 1187 static struct file_system_type mqueue_fs_type = { 1188 .name = "mqueue", 1189 .get_sb = mqueue_get_sb, 1190 .kill_sb = kill_litter_super, 1191 }; 1192 1193 static int msg_max_limit_min = DFLT_MSGMAX; 1194 static int msg_max_limit_max = HARD_MSGMAX; 1195 1196 static int msg_maxsize_limit_min = DFLT_MSGSIZEMAX; 1197 static int msg_maxsize_limit_max = INT_MAX; 1198 1199 static ctl_table mq_sysctls[] = { 1200 { 1201 .ctl_name = CTL_QUEUESMAX, 1202 .procname = "queues_max", 1203 .data = &queues_max, 1204 .maxlen = sizeof(int), 1205 .mode = 0644, 1206 .proc_handler = &proc_dointvec, 1207 }, 1208 { 1209 .ctl_name = CTL_MSGMAX, 1210 .procname = "msg_max", 1211 .data = &msg_max, 1212 .maxlen = sizeof(int), 1213 .mode = 0644, 1214 .proc_handler = &proc_dointvec_minmax, 1215 .extra1 = &msg_max_limit_min, 1216 .extra2 = &msg_max_limit_max, 1217 }, 1218 { 1219 .ctl_name = CTL_MSGSIZEMAX, 1220 .procname = "msgsize_max", 1221 .data = &msgsize_max, 1222 .maxlen = sizeof(int), 1223 .mode = 0644, 1224 .proc_handler = &proc_dointvec_minmax, 1225 .extra1 = &msg_maxsize_limit_min, 1226 .extra2 = &msg_maxsize_limit_max, 1227 }, 1228 { .ctl_name = 0 } 1229 }; 1230 1231 static ctl_table mq_sysctl_dir[] = { 1232 { 1233 .ctl_name = FS_MQUEUE, 1234 .procname = "mqueue", 1235 .mode = 0555, 1236 .child = mq_sysctls, 1237 }, 1238 { .ctl_name = 0 } 1239 }; 1240 1241 static ctl_table mq_sysctl_root[] = { 1242 { 1243 .ctl_name = CTL_FS, 1244 .procname = "fs", 1245 .mode = 0555, 1246 .child = mq_sysctl_dir, 1247 }, 1248 { .ctl_name = 0 } 1249 }; 1250 1251 static int __init init_mqueue_fs(void) 1252 { 1253 int error; 1254 1255 mqueue_inode_cachep = kmem_cache_create("mqueue_inode_cache", 1256 sizeof(struct mqueue_inode_info), 0, 1257 SLAB_HWCACHE_ALIGN, init_once, NULL); 1258 if (mqueue_inode_cachep == NULL) 1259 return -ENOMEM; 1260 1261 /* ignore failues - they are not fatal */ 1262 mq_sysctl_table = register_sysctl_table(mq_sysctl_root); 1263 1264 error = register_filesystem(&mqueue_fs_type); 1265 if (error) 1266 goto out_sysctl; 1267 1268 if (IS_ERR(mqueue_mnt = kern_mount(&mqueue_fs_type))) { 1269 error = PTR_ERR(mqueue_mnt); 1270 goto out_filesystem; 1271 } 1272 1273 /* internal initialization - not common for vfs */ 1274 queues_count = 0; 1275 spin_lock_init(&mq_lock); 1276 1277 return 0; 1278 1279 out_filesystem: 1280 unregister_filesystem(&mqueue_fs_type); 1281 out_sysctl: 1282 if (mq_sysctl_table) 1283 unregister_sysctl_table(mq_sysctl_table); 1284 kmem_cache_destroy(mqueue_inode_cachep); 1285 return error; 1286 } 1287 1288 __initcall(init_mqueue_fs); 1289