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 struct file *result; 602 int ret; 603 604 if (u_attr) { 605 ret = -EFAULT; 606 if (copy_from_user(&attr, u_attr, sizeof(attr))) 607 goto out; 608 ret = -EINVAL; 609 if (!mq_attr_ok(&attr)) 610 goto out; 611 /* store for use during create */ 612 dentry->d_fsdata = &attr; 613 } 614 615 mode &= ~current->fs->umask; 616 ret = mnt_want_write(mqueue_mnt); 617 if (ret) 618 goto out; 619 ret = vfs_create(dir->d_inode, dentry, mode, NULL); 620 dentry->d_fsdata = NULL; 621 if (ret) 622 goto out_drop_write; 623 624 result = dentry_open(dentry, mqueue_mnt, oflag); 625 /* 626 * dentry_open() took a persistent mnt_want_write(), 627 * so we can now drop this one. 628 */ 629 mnt_drop_write(mqueue_mnt); 630 return result; 631 632 out_drop_write: 633 mnt_drop_write(mqueue_mnt); 634 out: 635 dput(dentry); 636 mntput(mqueue_mnt); 637 return ERR_PTR(ret); 638 } 639 640 /* Opens existing queue */ 641 static struct file *do_open(struct dentry *dentry, int oflag) 642 { 643 static int oflag2acc[O_ACCMODE] = { MAY_READ, MAY_WRITE, 644 MAY_READ | MAY_WRITE }; 645 646 if ((oflag & O_ACCMODE) == (O_RDWR | O_WRONLY)) { 647 dput(dentry); 648 mntput(mqueue_mnt); 649 return ERR_PTR(-EINVAL); 650 } 651 652 if (permission(dentry->d_inode, oflag2acc[oflag & O_ACCMODE], NULL)) { 653 dput(dentry); 654 mntput(mqueue_mnt); 655 return ERR_PTR(-EACCES); 656 } 657 658 return dentry_open(dentry, mqueue_mnt, oflag); 659 } 660 661 asmlinkage long sys_mq_open(const char __user *u_name, int oflag, mode_t mode, 662 struct mq_attr __user *u_attr) 663 { 664 struct dentry *dentry; 665 struct file *filp; 666 char *name; 667 int fd, error; 668 669 error = audit_mq_open(oflag, mode, u_attr); 670 if (error != 0) 671 return error; 672 673 if (IS_ERR(name = getname(u_name))) 674 return PTR_ERR(name); 675 676 fd = get_unused_fd_flags(O_CLOEXEC); 677 if (fd < 0) 678 goto out_putname; 679 680 mutex_lock(&mqueue_mnt->mnt_root->d_inode->i_mutex); 681 dentry = lookup_one_len(name, mqueue_mnt->mnt_root, strlen(name)); 682 if (IS_ERR(dentry)) { 683 error = PTR_ERR(dentry); 684 goto out_err; 685 } 686 mntget(mqueue_mnt); 687 688 if (oflag & O_CREAT) { 689 if (dentry->d_inode) { /* entry already exists */ 690 audit_inode(name, dentry); 691 error = -EEXIST; 692 if (oflag & O_EXCL) 693 goto out; 694 filp = do_open(dentry, oflag); 695 } else { 696 filp = do_create(mqueue_mnt->mnt_root, dentry, 697 oflag, mode, u_attr); 698 } 699 } else { 700 error = -ENOENT; 701 if (!dentry->d_inode) 702 goto out; 703 audit_inode(name, dentry); 704 filp = do_open(dentry, oflag); 705 } 706 707 if (IS_ERR(filp)) { 708 error = PTR_ERR(filp); 709 goto out_putfd; 710 } 711 712 fd_install(fd, filp); 713 goto out_upsem; 714 715 out: 716 dput(dentry); 717 mntput(mqueue_mnt); 718 out_putfd: 719 put_unused_fd(fd); 720 out_err: 721 fd = error; 722 out_upsem: 723 mutex_unlock(&mqueue_mnt->mnt_root->d_inode->i_mutex); 724 out_putname: 725 putname(name); 726 return fd; 727 } 728 729 asmlinkage long sys_mq_unlink(const char __user *u_name) 730 { 731 int err; 732 char *name; 733 struct dentry *dentry; 734 struct inode *inode = NULL; 735 736 name = getname(u_name); 737 if (IS_ERR(name)) 738 return PTR_ERR(name); 739 740 mutex_lock_nested(&mqueue_mnt->mnt_root->d_inode->i_mutex, 741 I_MUTEX_PARENT); 742 dentry = lookup_one_len(name, mqueue_mnt->mnt_root, strlen(name)); 743 if (IS_ERR(dentry)) { 744 err = PTR_ERR(dentry); 745 goto out_unlock; 746 } 747 748 if (!dentry->d_inode) { 749 err = -ENOENT; 750 goto out_err; 751 } 752 753 inode = dentry->d_inode; 754 if (inode) 755 atomic_inc(&inode->i_count); 756 err = mnt_want_write(mqueue_mnt); 757 if (err) 758 goto out_err; 759 err = vfs_unlink(dentry->d_parent->d_inode, dentry); 760 mnt_drop_write(mqueue_mnt); 761 out_err: 762 dput(dentry); 763 764 out_unlock: 765 mutex_unlock(&mqueue_mnt->mnt_root->d_inode->i_mutex); 766 putname(name); 767 if (inode) 768 iput(inode); 769 770 return err; 771 } 772 773 /* Pipelined send and receive functions. 774 * 775 * If a receiver finds no waiting message, then it registers itself in the 776 * list of waiting receivers. A sender checks that list before adding the new 777 * message into the message array. If there is a waiting receiver, then it 778 * bypasses the message array and directly hands the message over to the 779 * receiver. 780 * The receiver accepts the message and returns without grabbing the queue 781 * spinlock. Therefore an intermediate STATE_PENDING state and memory barriers 782 * are necessary. The same algorithm is used for sysv semaphores, see 783 * ipc/sem.c for more details. 784 * 785 * The same algorithm is used for senders. 786 */ 787 788 /* pipelined_send() - send a message directly to the task waiting in 789 * sys_mq_timedreceive() (without inserting message into a queue). 790 */ 791 static inline void pipelined_send(struct mqueue_inode_info *info, 792 struct msg_msg *message, 793 struct ext_wait_queue *receiver) 794 { 795 receiver->msg = message; 796 list_del(&receiver->list); 797 receiver->state = STATE_PENDING; 798 wake_up_process(receiver->task); 799 smp_wmb(); 800 receiver->state = STATE_READY; 801 } 802 803 /* pipelined_receive() - if there is task waiting in sys_mq_timedsend() 804 * gets its message and put to the queue (we have one free place for sure). */ 805 static inline void pipelined_receive(struct mqueue_inode_info *info) 806 { 807 struct ext_wait_queue *sender = wq_get_first_waiter(info, SEND); 808 809 if (!sender) { 810 /* for poll */ 811 wake_up_interruptible(&info->wait_q); 812 return; 813 } 814 msg_insert(sender->msg, info); 815 list_del(&sender->list); 816 sender->state = STATE_PENDING; 817 wake_up_process(sender->task); 818 smp_wmb(); 819 sender->state = STATE_READY; 820 } 821 822 asmlinkage long sys_mq_timedsend(mqd_t mqdes, const char __user *u_msg_ptr, 823 size_t msg_len, unsigned int msg_prio, 824 const struct timespec __user *u_abs_timeout) 825 { 826 struct file *filp; 827 struct inode *inode; 828 struct ext_wait_queue wait; 829 struct ext_wait_queue *receiver; 830 struct msg_msg *msg_ptr; 831 struct mqueue_inode_info *info; 832 long timeout; 833 int ret; 834 835 ret = audit_mq_timedsend(mqdes, msg_len, msg_prio, u_abs_timeout); 836 if (ret != 0) 837 return ret; 838 839 if (unlikely(msg_prio >= (unsigned long) MQ_PRIO_MAX)) 840 return -EINVAL; 841 842 timeout = prepare_timeout(u_abs_timeout); 843 844 ret = -EBADF; 845 filp = fget(mqdes); 846 if (unlikely(!filp)) 847 goto out; 848 849 inode = filp->f_path.dentry->d_inode; 850 if (unlikely(filp->f_op != &mqueue_file_operations)) 851 goto out_fput; 852 info = MQUEUE_I(inode); 853 audit_inode(NULL, filp->f_path.dentry); 854 855 if (unlikely(!(filp->f_mode & FMODE_WRITE))) 856 goto out_fput; 857 858 if (unlikely(msg_len > info->attr.mq_msgsize)) { 859 ret = -EMSGSIZE; 860 goto out_fput; 861 } 862 863 /* First try to allocate memory, before doing anything with 864 * existing queues. */ 865 msg_ptr = load_msg(u_msg_ptr, msg_len); 866 if (IS_ERR(msg_ptr)) { 867 ret = PTR_ERR(msg_ptr); 868 goto out_fput; 869 } 870 msg_ptr->m_ts = msg_len; 871 msg_ptr->m_type = msg_prio; 872 873 spin_lock(&info->lock); 874 875 if (info->attr.mq_curmsgs == info->attr.mq_maxmsg) { 876 if (filp->f_flags & O_NONBLOCK) { 877 spin_unlock(&info->lock); 878 ret = -EAGAIN; 879 } else if (unlikely(timeout < 0)) { 880 spin_unlock(&info->lock); 881 ret = timeout; 882 } else { 883 wait.task = current; 884 wait.msg = (void *) msg_ptr; 885 wait.state = STATE_NONE; 886 ret = wq_sleep(info, SEND, timeout, &wait); 887 } 888 if (ret < 0) 889 free_msg(msg_ptr); 890 } else { 891 receiver = wq_get_first_waiter(info, RECV); 892 if (receiver) { 893 pipelined_send(info, msg_ptr, receiver); 894 } else { 895 /* adds message to the queue */ 896 msg_insert(msg_ptr, info); 897 __do_notify(info); 898 } 899 inode->i_atime = inode->i_mtime = inode->i_ctime = 900 CURRENT_TIME; 901 spin_unlock(&info->lock); 902 ret = 0; 903 } 904 out_fput: 905 fput(filp); 906 out: 907 return ret; 908 } 909 910 asmlinkage ssize_t sys_mq_timedreceive(mqd_t mqdes, char __user *u_msg_ptr, 911 size_t msg_len, unsigned int __user *u_msg_prio, 912 const struct timespec __user *u_abs_timeout) 913 { 914 long timeout; 915 ssize_t ret; 916 struct msg_msg *msg_ptr; 917 struct file *filp; 918 struct inode *inode; 919 struct mqueue_inode_info *info; 920 struct ext_wait_queue wait; 921 922 ret = audit_mq_timedreceive(mqdes, msg_len, u_msg_prio, u_abs_timeout); 923 if (ret != 0) 924 return ret; 925 926 timeout = prepare_timeout(u_abs_timeout); 927 928 ret = -EBADF; 929 filp = fget(mqdes); 930 if (unlikely(!filp)) 931 goto out; 932 933 inode = filp->f_path.dentry->d_inode; 934 if (unlikely(filp->f_op != &mqueue_file_operations)) 935 goto out_fput; 936 info = MQUEUE_I(inode); 937 audit_inode(NULL, filp->f_path.dentry); 938 939 if (unlikely(!(filp->f_mode & FMODE_READ))) 940 goto out_fput; 941 942 /* checks if buffer is big enough */ 943 if (unlikely(msg_len < info->attr.mq_msgsize)) { 944 ret = -EMSGSIZE; 945 goto out_fput; 946 } 947 948 spin_lock(&info->lock); 949 if (info->attr.mq_curmsgs == 0) { 950 if (filp->f_flags & O_NONBLOCK) { 951 spin_unlock(&info->lock); 952 ret = -EAGAIN; 953 msg_ptr = NULL; 954 } else if (unlikely(timeout < 0)) { 955 spin_unlock(&info->lock); 956 ret = timeout; 957 msg_ptr = NULL; 958 } else { 959 wait.task = current; 960 wait.state = STATE_NONE; 961 ret = wq_sleep(info, RECV, timeout, &wait); 962 msg_ptr = wait.msg; 963 } 964 } else { 965 msg_ptr = msg_get(info); 966 967 inode->i_atime = inode->i_mtime = inode->i_ctime = 968 CURRENT_TIME; 969 970 /* There is now free space in queue. */ 971 pipelined_receive(info); 972 spin_unlock(&info->lock); 973 ret = 0; 974 } 975 if (ret == 0) { 976 ret = msg_ptr->m_ts; 977 978 if ((u_msg_prio && put_user(msg_ptr->m_type, u_msg_prio)) || 979 store_msg(u_msg_ptr, msg_ptr, msg_ptr->m_ts)) { 980 ret = -EFAULT; 981 } 982 free_msg(msg_ptr); 983 } 984 out_fput: 985 fput(filp); 986 out: 987 return ret; 988 } 989 990 /* 991 * Notes: the case when user wants us to deregister (with NULL as pointer) 992 * and he isn't currently owner of notification, will be silently discarded. 993 * It isn't explicitly defined in the POSIX. 994 */ 995 asmlinkage long sys_mq_notify(mqd_t mqdes, 996 const struct sigevent __user *u_notification) 997 { 998 int ret; 999 struct file *filp; 1000 struct sock *sock; 1001 struct inode *inode; 1002 struct sigevent notification; 1003 struct mqueue_inode_info *info; 1004 struct sk_buff *nc; 1005 1006 ret = audit_mq_notify(mqdes, u_notification); 1007 if (ret != 0) 1008 return ret; 1009 1010 nc = NULL; 1011 sock = NULL; 1012 if (u_notification != NULL) { 1013 if (copy_from_user(¬ification, u_notification, 1014 sizeof(struct sigevent))) 1015 return -EFAULT; 1016 1017 if (unlikely(notification.sigev_notify != SIGEV_NONE && 1018 notification.sigev_notify != SIGEV_SIGNAL && 1019 notification.sigev_notify != SIGEV_THREAD)) 1020 return -EINVAL; 1021 if (notification.sigev_notify == SIGEV_SIGNAL && 1022 !valid_signal(notification.sigev_signo)) { 1023 return -EINVAL; 1024 } 1025 if (notification.sigev_notify == SIGEV_THREAD) { 1026 long timeo; 1027 1028 /* create the notify skb */ 1029 nc = alloc_skb(NOTIFY_COOKIE_LEN, GFP_KERNEL); 1030 ret = -ENOMEM; 1031 if (!nc) 1032 goto out; 1033 ret = -EFAULT; 1034 if (copy_from_user(nc->data, 1035 notification.sigev_value.sival_ptr, 1036 NOTIFY_COOKIE_LEN)) { 1037 goto out; 1038 } 1039 1040 /* TODO: add a header? */ 1041 skb_put(nc, NOTIFY_COOKIE_LEN); 1042 /* and attach it to the socket */ 1043 retry: 1044 filp = fget(notification.sigev_signo); 1045 ret = -EBADF; 1046 if (!filp) 1047 goto out; 1048 sock = netlink_getsockbyfilp(filp); 1049 fput(filp); 1050 if (IS_ERR(sock)) { 1051 ret = PTR_ERR(sock); 1052 sock = NULL; 1053 goto out; 1054 } 1055 1056 timeo = MAX_SCHEDULE_TIMEOUT; 1057 ret = netlink_attachskb(sock, nc, 0, &timeo, NULL); 1058 if (ret == 1) 1059 goto retry; 1060 if (ret) { 1061 sock = NULL; 1062 nc = NULL; 1063 goto out; 1064 } 1065 } 1066 } 1067 1068 ret = -EBADF; 1069 filp = fget(mqdes); 1070 if (!filp) 1071 goto out; 1072 1073 inode = filp->f_path.dentry->d_inode; 1074 if (unlikely(filp->f_op != &mqueue_file_operations)) 1075 goto out_fput; 1076 info = MQUEUE_I(inode); 1077 1078 ret = 0; 1079 spin_lock(&info->lock); 1080 if (u_notification == NULL) { 1081 if (info->notify_owner == task_tgid(current)) { 1082 remove_notification(info); 1083 inode->i_atime = inode->i_ctime = CURRENT_TIME; 1084 } 1085 } else if (info->notify_owner != NULL) { 1086 ret = -EBUSY; 1087 } else { 1088 switch (notification.sigev_notify) { 1089 case SIGEV_NONE: 1090 info->notify.sigev_notify = SIGEV_NONE; 1091 break; 1092 case SIGEV_THREAD: 1093 info->notify_sock = sock; 1094 info->notify_cookie = nc; 1095 sock = NULL; 1096 nc = NULL; 1097 info->notify.sigev_notify = SIGEV_THREAD; 1098 break; 1099 case SIGEV_SIGNAL: 1100 info->notify.sigev_signo = notification.sigev_signo; 1101 info->notify.sigev_value = notification.sigev_value; 1102 info->notify.sigev_notify = SIGEV_SIGNAL; 1103 break; 1104 } 1105 1106 info->notify_owner = get_pid(task_tgid(current)); 1107 inode->i_atime = inode->i_ctime = CURRENT_TIME; 1108 } 1109 spin_unlock(&info->lock); 1110 out_fput: 1111 fput(filp); 1112 out: 1113 if (sock) { 1114 netlink_detachskb(sock, nc); 1115 } else if (nc) { 1116 dev_kfree_skb(nc); 1117 } 1118 return ret; 1119 } 1120 1121 asmlinkage long sys_mq_getsetattr(mqd_t mqdes, 1122 const struct mq_attr __user *u_mqstat, 1123 struct mq_attr __user *u_omqstat) 1124 { 1125 int ret; 1126 struct mq_attr mqstat, omqstat; 1127 struct file *filp; 1128 struct inode *inode; 1129 struct mqueue_inode_info *info; 1130 1131 if (u_mqstat != NULL) { 1132 if (copy_from_user(&mqstat, u_mqstat, sizeof(struct mq_attr))) 1133 return -EFAULT; 1134 if (mqstat.mq_flags & (~O_NONBLOCK)) 1135 return -EINVAL; 1136 } 1137 1138 ret = -EBADF; 1139 filp = fget(mqdes); 1140 if (!filp) 1141 goto out; 1142 1143 inode = filp->f_path.dentry->d_inode; 1144 if (unlikely(filp->f_op != &mqueue_file_operations)) 1145 goto out_fput; 1146 info = MQUEUE_I(inode); 1147 1148 spin_lock(&info->lock); 1149 1150 omqstat = info->attr; 1151 omqstat.mq_flags = filp->f_flags & O_NONBLOCK; 1152 if (u_mqstat) { 1153 ret = audit_mq_getsetattr(mqdes, &mqstat); 1154 if (ret != 0) { 1155 spin_unlock(&info->lock); 1156 goto out_fput; 1157 } 1158 if (mqstat.mq_flags & O_NONBLOCK) 1159 filp->f_flags |= O_NONBLOCK; 1160 else 1161 filp->f_flags &= ~O_NONBLOCK; 1162 1163 inode->i_atime = inode->i_ctime = CURRENT_TIME; 1164 } 1165 1166 spin_unlock(&info->lock); 1167 1168 ret = 0; 1169 if (u_omqstat != NULL && copy_to_user(u_omqstat, &omqstat, 1170 sizeof(struct mq_attr))) 1171 ret = -EFAULT; 1172 1173 out_fput: 1174 fput(filp); 1175 out: 1176 return ret; 1177 } 1178 1179 static const struct inode_operations mqueue_dir_inode_operations = { 1180 .lookup = simple_lookup, 1181 .create = mqueue_create, 1182 .unlink = mqueue_unlink, 1183 }; 1184 1185 static const struct file_operations mqueue_file_operations = { 1186 .flush = mqueue_flush_file, 1187 .poll = mqueue_poll_file, 1188 .read = mqueue_read_file, 1189 }; 1190 1191 static struct super_operations mqueue_super_ops = { 1192 .alloc_inode = mqueue_alloc_inode, 1193 .destroy_inode = mqueue_destroy_inode, 1194 .statfs = simple_statfs, 1195 .delete_inode = mqueue_delete_inode, 1196 .drop_inode = generic_delete_inode, 1197 }; 1198 1199 static struct file_system_type mqueue_fs_type = { 1200 .name = "mqueue", 1201 .get_sb = mqueue_get_sb, 1202 .kill_sb = kill_litter_super, 1203 }; 1204 1205 static int msg_max_limit_min = DFLT_MSGMAX; 1206 static int msg_max_limit_max = HARD_MSGMAX; 1207 1208 static int msg_maxsize_limit_min = DFLT_MSGSIZEMAX; 1209 static int msg_maxsize_limit_max = INT_MAX; 1210 1211 static ctl_table mq_sysctls[] = { 1212 { 1213 .procname = "queues_max", 1214 .data = &queues_max, 1215 .maxlen = sizeof(int), 1216 .mode = 0644, 1217 .proc_handler = &proc_dointvec, 1218 }, 1219 { 1220 .procname = "msg_max", 1221 .data = &msg_max, 1222 .maxlen = sizeof(int), 1223 .mode = 0644, 1224 .proc_handler = &proc_dointvec_minmax, 1225 .extra1 = &msg_max_limit_min, 1226 .extra2 = &msg_max_limit_max, 1227 }, 1228 { 1229 .procname = "msgsize_max", 1230 .data = &msgsize_max, 1231 .maxlen = sizeof(int), 1232 .mode = 0644, 1233 .proc_handler = &proc_dointvec_minmax, 1234 .extra1 = &msg_maxsize_limit_min, 1235 .extra2 = &msg_maxsize_limit_max, 1236 }, 1237 { .ctl_name = 0 } 1238 }; 1239 1240 static ctl_table mq_sysctl_dir[] = { 1241 { 1242 .procname = "mqueue", 1243 .mode = 0555, 1244 .child = mq_sysctls, 1245 }, 1246 { .ctl_name = 0 } 1247 }; 1248 1249 static ctl_table mq_sysctl_root[] = { 1250 { 1251 .ctl_name = CTL_FS, 1252 .procname = "fs", 1253 .mode = 0555, 1254 .child = mq_sysctl_dir, 1255 }, 1256 { .ctl_name = 0 } 1257 }; 1258 1259 static int __init init_mqueue_fs(void) 1260 { 1261 int error; 1262 1263 mqueue_inode_cachep = kmem_cache_create("mqueue_inode_cache", 1264 sizeof(struct mqueue_inode_info), 0, 1265 SLAB_HWCACHE_ALIGN, init_once); 1266 if (mqueue_inode_cachep == NULL) 1267 return -ENOMEM; 1268 1269 /* ignore failues - they are not fatal */ 1270 mq_sysctl_table = register_sysctl_table(mq_sysctl_root); 1271 1272 error = register_filesystem(&mqueue_fs_type); 1273 if (error) 1274 goto out_sysctl; 1275 1276 if (IS_ERR(mqueue_mnt = kern_mount(&mqueue_fs_type))) { 1277 error = PTR_ERR(mqueue_mnt); 1278 goto out_filesystem; 1279 } 1280 1281 /* internal initialization - not common for vfs */ 1282 queues_count = 0; 1283 spin_lock_init(&mq_lock); 1284 1285 return 0; 1286 1287 out_filesystem: 1288 unregister_filesystem(&mqueue_fs_type); 1289 out_sysctl: 1290 if (mq_sysctl_table) 1291 unregister_sysctl_table(mq_sysctl_table); 1292 kmem_cache_destroy(mqueue_inode_cachep); 1293 return error; 1294 } 1295 1296 __initcall(init_mqueue_fs); 1297