1 /* 2 * POSIX message queues filesystem for Linux. 3 * 4 * Copyright (C) 2003,2004 Krzysztof Benedyczak ([email protected]) 5 * Michal Wronski ([email protected]) 6 * 7 * Spinlocks: Mohamed Abbas ([email protected]) 8 * Lockless receive & send, fd based notify: 9 * Manfred Spraul ([email protected]) 10 * 11 * Audit: George Wilson ([email protected]) 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 * Define the ranges various user-specified maximum values can 57 * be set to. 58 */ 59 #define MIN_MSGMAX 1 /* min value for msg_max */ 60 #define MAX_MSGMAX HARD_MSGMAX /* max value for msg_max */ 61 #define MIN_MSGSIZEMAX 128 /* min value for msgsize_max */ 62 #define MAX_MSGSIZEMAX (8192*128) /* max value for msgsize_max */ 63 64 struct ext_wait_queue { /* queue of sleeping tasks */ 65 struct task_struct *task; 66 struct list_head list; 67 struct msg_msg *msg; /* ptr of loaded message */ 68 int state; /* one of STATE_* values */ 69 }; 70 71 struct mqueue_inode_info { 72 spinlock_t lock; 73 struct inode vfs_inode; 74 wait_queue_head_t wait_q; 75 76 struct msg_msg **messages; 77 struct mq_attr attr; 78 79 struct sigevent notify; 80 struct pid* notify_owner; 81 struct user_struct *user; /* user who created, for accounting */ 82 struct sock *notify_sock; 83 struct sk_buff *notify_cookie; 84 85 /* for tasks waiting for free space and messages, respectively */ 86 struct ext_wait_queue e_wait_q[2]; 87 88 unsigned long qsize; /* size of queue in memory (sum of all msgs) */ 89 }; 90 91 static const struct inode_operations mqueue_dir_inode_operations; 92 static const struct file_operations mqueue_file_operations; 93 static struct super_operations mqueue_super_ops; 94 static void remove_notification(struct mqueue_inode_info *info); 95 96 static spinlock_t mq_lock; 97 static struct kmem_cache *mqueue_inode_cachep; 98 static struct vfsmount *mqueue_mnt; 99 100 static unsigned int queues_count; 101 static unsigned int queues_max = DFLT_QUEUESMAX; 102 static unsigned int msg_max = DFLT_MSGMAX; 103 static unsigned int msgsize_max = DFLT_MSGSIZEMAX; 104 105 static struct ctl_table_header * mq_sysctl_table; 106 107 static inline struct mqueue_inode_info *MQUEUE_I(struct inode *inode) 108 { 109 return container_of(inode, struct mqueue_inode_info, vfs_inode); 110 } 111 112 static struct inode *mqueue_get_inode(struct super_block *sb, int mode, 113 struct mq_attr *attr) 114 { 115 struct user_struct *u = current_user(); 116 struct inode *inode; 117 118 inode = new_inode(sb); 119 if (inode) { 120 inode->i_mode = mode; 121 inode->i_uid = current_fsuid(); 122 inode->i_gid = current_fsgid(); 123 inode->i_mtime = inode->i_ctime = inode->i_atime = 124 CURRENT_TIME; 125 126 if (S_ISREG(mode)) { 127 struct mqueue_inode_info *info; 128 struct task_struct *p = current; 129 unsigned long mq_bytes, mq_msg_tblsz; 130 131 inode->i_fop = &mqueue_file_operations; 132 inode->i_size = FILENT_SIZE; 133 /* mqueue specific info */ 134 info = MQUEUE_I(inode); 135 spin_lock_init(&info->lock); 136 init_waitqueue_head(&info->wait_q); 137 INIT_LIST_HEAD(&info->e_wait_q[0].list); 138 INIT_LIST_HEAD(&info->e_wait_q[1].list); 139 info->messages = NULL; 140 info->notify_owner = NULL; 141 info->qsize = 0; 142 info->user = NULL; /* set when all is ok */ 143 memset(&info->attr, 0, sizeof(info->attr)); 144 info->attr.mq_maxmsg = msg_max; 145 info->attr.mq_msgsize = msgsize_max; 146 if (attr) { 147 info->attr.mq_maxmsg = attr->mq_maxmsg; 148 info->attr.mq_msgsize = attr->mq_msgsize; 149 } 150 mq_msg_tblsz = info->attr.mq_maxmsg * sizeof(struct msg_msg *); 151 mq_bytes = (mq_msg_tblsz + 152 (info->attr.mq_maxmsg * info->attr.mq_msgsize)); 153 154 spin_lock(&mq_lock); 155 if (u->mq_bytes + mq_bytes < u->mq_bytes || 156 u->mq_bytes + mq_bytes > 157 p->signal->rlim[RLIMIT_MSGQUEUE].rlim_cur) { 158 spin_unlock(&mq_lock); 159 goto out_inode; 160 } 161 u->mq_bytes += mq_bytes; 162 spin_unlock(&mq_lock); 163 164 info->messages = kmalloc(mq_msg_tblsz, GFP_KERNEL); 165 if (!info->messages) { 166 spin_lock(&mq_lock); 167 u->mq_bytes -= mq_bytes; 168 spin_unlock(&mq_lock); 169 goto out_inode; 170 } 171 /* all is ok */ 172 info->user = get_uid(u); 173 } else if (S_ISDIR(mode)) { 174 inc_nlink(inode); 175 /* Some things misbehave if size == 0 on a directory */ 176 inode->i_size = 2 * DIRENT_SIZE; 177 inode->i_op = &mqueue_dir_inode_operations; 178 inode->i_fop = &simple_dir_operations; 179 } 180 } 181 return inode; 182 out_inode: 183 make_bad_inode(inode); 184 iput(inode); 185 return NULL; 186 } 187 188 static int mqueue_fill_super(struct super_block *sb, void *data, int silent) 189 { 190 struct inode *inode; 191 192 sb->s_blocksize = PAGE_CACHE_SIZE; 193 sb->s_blocksize_bits = PAGE_CACHE_SHIFT; 194 sb->s_magic = MQUEUE_MAGIC; 195 sb->s_op = &mqueue_super_ops; 196 197 inode = mqueue_get_inode(sb, S_IFDIR | S_ISVTX | S_IRWXUGO, NULL); 198 if (!inode) 199 return -ENOMEM; 200 201 sb->s_root = d_alloc_root(inode); 202 if (!sb->s_root) { 203 iput(inode); 204 return -ENOMEM; 205 } 206 207 return 0; 208 } 209 210 static int mqueue_get_sb(struct file_system_type *fs_type, 211 int flags, const char *dev_name, 212 void *data, struct vfsmount *mnt) 213 { 214 return get_sb_single(fs_type, flags, data, mqueue_fill_super, mnt); 215 } 216 217 static void init_once(void *foo) 218 { 219 struct mqueue_inode_info *p = (struct mqueue_inode_info *) foo; 220 221 inode_init_once(&p->vfs_inode); 222 } 223 224 static struct inode *mqueue_alloc_inode(struct super_block *sb) 225 { 226 struct mqueue_inode_info *ei; 227 228 ei = kmem_cache_alloc(mqueue_inode_cachep, GFP_KERNEL); 229 if (!ei) 230 return NULL; 231 return &ei->vfs_inode; 232 } 233 234 static void mqueue_destroy_inode(struct inode *inode) 235 { 236 kmem_cache_free(mqueue_inode_cachep, MQUEUE_I(inode)); 237 } 238 239 static void mqueue_delete_inode(struct inode *inode) 240 { 241 struct mqueue_inode_info *info; 242 struct user_struct *user; 243 unsigned long mq_bytes; 244 int i; 245 246 if (S_ISDIR(inode->i_mode)) { 247 clear_inode(inode); 248 return; 249 } 250 info = MQUEUE_I(inode); 251 spin_lock(&info->lock); 252 for (i = 0; i < info->attr.mq_curmsgs; i++) 253 free_msg(info->messages[i]); 254 kfree(info->messages); 255 spin_unlock(&info->lock); 256 257 clear_inode(inode); 258 259 mq_bytes = (info->attr.mq_maxmsg * sizeof(struct msg_msg *) + 260 (info->attr.mq_maxmsg * info->attr.mq_msgsize)); 261 user = info->user; 262 if (user) { 263 spin_lock(&mq_lock); 264 user->mq_bytes -= mq_bytes; 265 queues_count--; 266 spin_unlock(&mq_lock); 267 free_uid(user); 268 } 269 } 270 271 static int mqueue_create(struct inode *dir, struct dentry *dentry, 272 int mode, struct nameidata *nd) 273 { 274 struct inode *inode; 275 struct mq_attr *attr = dentry->d_fsdata; 276 int error; 277 278 spin_lock(&mq_lock); 279 if (queues_count >= queues_max && !capable(CAP_SYS_RESOURCE)) { 280 error = -ENOSPC; 281 goto out_lock; 282 } 283 queues_count++; 284 spin_unlock(&mq_lock); 285 286 inode = mqueue_get_inode(dir->i_sb, mode, attr); 287 if (!inode) { 288 error = -ENOMEM; 289 spin_lock(&mq_lock); 290 queues_count--; 291 goto out_lock; 292 } 293 294 dir->i_size += DIRENT_SIZE; 295 dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME; 296 297 d_instantiate(dentry, inode); 298 dget(dentry); 299 return 0; 300 out_lock: 301 spin_unlock(&mq_lock); 302 return error; 303 } 304 305 static int mqueue_unlink(struct inode *dir, struct dentry *dentry) 306 { 307 struct inode *inode = dentry->d_inode; 308 309 dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME; 310 dir->i_size -= DIRENT_SIZE; 311 drop_nlink(inode); 312 dput(dentry); 313 return 0; 314 } 315 316 /* 317 * This is routine for system read from queue file. 318 * To avoid mess with doing here some sort of mq_receive we allow 319 * to read only queue size & notification info (the only values 320 * that are interesting from user point of view and aren't accessible 321 * through std routines) 322 */ 323 static ssize_t mqueue_read_file(struct file *filp, char __user *u_data, 324 size_t count, loff_t *off) 325 { 326 struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode); 327 char buffer[FILENT_SIZE]; 328 ssize_t ret; 329 330 spin_lock(&info->lock); 331 snprintf(buffer, sizeof(buffer), 332 "QSIZE:%-10lu NOTIFY:%-5d SIGNO:%-5d NOTIFY_PID:%-6d\n", 333 info->qsize, 334 info->notify_owner ? info->notify.sigev_notify : 0, 335 (info->notify_owner && 336 info->notify.sigev_notify == SIGEV_SIGNAL) ? 337 info->notify.sigev_signo : 0, 338 pid_vnr(info->notify_owner)); 339 spin_unlock(&info->lock); 340 buffer[sizeof(buffer)-1] = '\0'; 341 342 ret = simple_read_from_buffer(u_data, count, off, buffer, 343 strlen(buffer)); 344 if (ret <= 0) 345 return ret; 346 347 filp->f_path.dentry->d_inode->i_atime = filp->f_path.dentry->d_inode->i_ctime = CURRENT_TIME; 348 return ret; 349 } 350 351 static int mqueue_flush_file(struct file *filp, fl_owner_t id) 352 { 353 struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode); 354 355 spin_lock(&info->lock); 356 if (task_tgid(current) == info->notify_owner) 357 remove_notification(info); 358 359 spin_unlock(&info->lock); 360 return 0; 361 } 362 363 static unsigned int mqueue_poll_file(struct file *filp, struct poll_table_struct *poll_tab) 364 { 365 struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode); 366 int retval = 0; 367 368 poll_wait(filp, &info->wait_q, poll_tab); 369 370 spin_lock(&info->lock); 371 if (info->attr.mq_curmsgs) 372 retval = POLLIN | POLLRDNORM; 373 374 if (info->attr.mq_curmsgs < info->attr.mq_maxmsg) 375 retval |= POLLOUT | POLLWRNORM; 376 spin_unlock(&info->lock); 377 378 return retval; 379 } 380 381 /* Adds current to info->e_wait_q[sr] before element with smaller prio */ 382 static void wq_add(struct mqueue_inode_info *info, int sr, 383 struct ext_wait_queue *ewp) 384 { 385 struct ext_wait_queue *walk; 386 387 ewp->task = current; 388 389 list_for_each_entry(walk, &info->e_wait_q[sr].list, list) { 390 if (walk->task->static_prio <= current->static_prio) { 391 list_add_tail(&ewp->list, &walk->list); 392 return; 393 } 394 } 395 list_add_tail(&ewp->list, &info->e_wait_q[sr].list); 396 } 397 398 /* 399 * Puts current task to sleep. Caller must hold queue lock. After return 400 * lock isn't held. 401 * sr: SEND or RECV 402 */ 403 static int wq_sleep(struct mqueue_inode_info *info, int sr, 404 long timeout, struct ext_wait_queue *ewp) 405 { 406 int retval; 407 signed long time; 408 409 wq_add(info, sr, ewp); 410 411 for (;;) { 412 set_current_state(TASK_INTERRUPTIBLE); 413 414 spin_unlock(&info->lock); 415 time = schedule_timeout(timeout); 416 417 while (ewp->state == STATE_PENDING) 418 cpu_relax(); 419 420 if (ewp->state == STATE_READY) { 421 retval = 0; 422 goto out; 423 } 424 spin_lock(&info->lock); 425 if (ewp->state == STATE_READY) { 426 retval = 0; 427 goto out_unlock; 428 } 429 if (signal_pending(current)) { 430 retval = -ERESTARTSYS; 431 break; 432 } 433 if (time == 0) { 434 retval = -ETIMEDOUT; 435 break; 436 } 437 } 438 list_del(&ewp->list); 439 out_unlock: 440 spin_unlock(&info->lock); 441 out: 442 return retval; 443 } 444 445 /* 446 * Returns waiting task that should be serviced first or NULL if none exists 447 */ 448 static struct ext_wait_queue *wq_get_first_waiter( 449 struct mqueue_inode_info *info, int sr) 450 { 451 struct list_head *ptr; 452 453 ptr = info->e_wait_q[sr].list.prev; 454 if (ptr == &info->e_wait_q[sr].list) 455 return NULL; 456 return list_entry(ptr, struct ext_wait_queue, list); 457 } 458 459 /* Auxiliary functions to manipulate messages' list */ 460 static void msg_insert(struct msg_msg *ptr, struct mqueue_inode_info *info) 461 { 462 int k; 463 464 k = info->attr.mq_curmsgs - 1; 465 while (k >= 0 && info->messages[k]->m_type >= ptr->m_type) { 466 info->messages[k + 1] = info->messages[k]; 467 k--; 468 } 469 info->attr.mq_curmsgs++; 470 info->qsize += ptr->m_ts; 471 info->messages[k + 1] = ptr; 472 } 473 474 static inline struct msg_msg *msg_get(struct mqueue_inode_info *info) 475 { 476 info->qsize -= info->messages[--info->attr.mq_curmsgs]->m_ts; 477 return info->messages[info->attr.mq_curmsgs]; 478 } 479 480 static inline void set_cookie(struct sk_buff *skb, char code) 481 { 482 ((char*)skb->data)[NOTIFY_COOKIE_LEN-1] = code; 483 } 484 485 /* 486 * The next function is only to split too long sys_mq_timedsend 487 */ 488 static void __do_notify(struct mqueue_inode_info *info) 489 { 490 /* notification 491 * invoked when there is registered process and there isn't process 492 * waiting synchronously for message AND state of queue changed from 493 * empty to not empty. Here we are sure that no one is waiting 494 * synchronously. */ 495 if (info->notify_owner && 496 info->attr.mq_curmsgs == 1) { 497 struct siginfo sig_i; 498 switch (info->notify.sigev_notify) { 499 case SIGEV_NONE: 500 break; 501 case SIGEV_SIGNAL: 502 /* sends signal */ 503 504 sig_i.si_signo = info->notify.sigev_signo; 505 sig_i.si_errno = 0; 506 sig_i.si_code = SI_MESGQ; 507 sig_i.si_value = info->notify.sigev_value; 508 sig_i.si_pid = task_tgid_vnr(current); 509 sig_i.si_uid = current_uid(); 510 511 kill_pid_info(info->notify.sigev_signo, 512 &sig_i, info->notify_owner); 513 break; 514 case SIGEV_THREAD: 515 set_cookie(info->notify_cookie, NOTIFY_WOKENUP); 516 netlink_sendskb(info->notify_sock, info->notify_cookie); 517 break; 518 } 519 /* after notification unregisters process */ 520 put_pid(info->notify_owner); 521 info->notify_owner = NULL; 522 } 523 wake_up(&info->wait_q); 524 } 525 526 static long prepare_timeout(struct timespec *p) 527 { 528 struct timespec nowts; 529 long timeout; 530 531 if (p) { 532 if (unlikely(p->tv_nsec < 0 || p->tv_sec < 0 533 || p->tv_nsec >= NSEC_PER_SEC)) 534 return -EINVAL; 535 nowts = CURRENT_TIME; 536 /* first subtract as jiffies can't be too big */ 537 p->tv_sec -= nowts.tv_sec; 538 if (p->tv_nsec < nowts.tv_nsec) { 539 p->tv_nsec += NSEC_PER_SEC; 540 p->tv_sec--; 541 } 542 p->tv_nsec -= nowts.tv_nsec; 543 if (p->tv_sec < 0) 544 return 0; 545 546 timeout = timespec_to_jiffies(p) + 1; 547 } else 548 return MAX_SCHEDULE_TIMEOUT; 549 550 return timeout; 551 } 552 553 static void remove_notification(struct mqueue_inode_info *info) 554 { 555 if (info->notify_owner != NULL && 556 info->notify.sigev_notify == SIGEV_THREAD) { 557 set_cookie(info->notify_cookie, NOTIFY_REMOVED); 558 netlink_sendskb(info->notify_sock, info->notify_cookie); 559 } 560 put_pid(info->notify_owner); 561 info->notify_owner = NULL; 562 } 563 564 static int mq_attr_ok(struct mq_attr *attr) 565 { 566 if (attr->mq_maxmsg <= 0 || attr->mq_msgsize <= 0) 567 return 0; 568 if (capable(CAP_SYS_RESOURCE)) { 569 if (attr->mq_maxmsg > HARD_MSGMAX) 570 return 0; 571 } else { 572 if (attr->mq_maxmsg > msg_max || 573 attr->mq_msgsize > msgsize_max) 574 return 0; 575 } 576 /* check for overflow */ 577 if (attr->mq_msgsize > ULONG_MAX/attr->mq_maxmsg) 578 return 0; 579 if ((unsigned long)(attr->mq_maxmsg * attr->mq_msgsize) + 580 (attr->mq_maxmsg * sizeof (struct msg_msg *)) < 581 (unsigned long)(attr->mq_maxmsg * attr->mq_msgsize)) 582 return 0; 583 return 1; 584 } 585 586 /* 587 * Invoked when creating a new queue via sys_mq_open 588 */ 589 static struct file *do_create(struct dentry *dir, struct dentry *dentry, 590 int oflag, mode_t mode, struct mq_attr *attr) 591 { 592 const struct cred *cred = current_cred(); 593 struct file *result; 594 int ret; 595 596 if (attr) { 597 ret = -EINVAL; 598 if (!mq_attr_ok(attr)) 599 goto out; 600 /* store for use during create */ 601 dentry->d_fsdata = attr; 602 } 603 604 mode &= ~current->fs->umask; 605 ret = mnt_want_write(mqueue_mnt); 606 if (ret) 607 goto out; 608 ret = vfs_create(dir->d_inode, dentry, mode, NULL); 609 dentry->d_fsdata = NULL; 610 if (ret) 611 goto out_drop_write; 612 613 result = dentry_open(dentry, mqueue_mnt, oflag, cred); 614 /* 615 * dentry_open() took a persistent mnt_want_write(), 616 * so we can now drop this one. 617 */ 618 mnt_drop_write(mqueue_mnt); 619 return result; 620 621 out_drop_write: 622 mnt_drop_write(mqueue_mnt); 623 out: 624 dput(dentry); 625 mntput(mqueue_mnt); 626 return ERR_PTR(ret); 627 } 628 629 /* Opens existing queue */ 630 static struct file *do_open(struct dentry *dentry, int oflag) 631 { 632 const struct cred *cred = current_cred(); 633 634 static const int oflag2acc[O_ACCMODE] = { MAY_READ, MAY_WRITE, 635 MAY_READ | MAY_WRITE }; 636 637 if ((oflag & O_ACCMODE) == (O_RDWR | O_WRONLY)) { 638 dput(dentry); 639 mntput(mqueue_mnt); 640 return ERR_PTR(-EINVAL); 641 } 642 643 if (inode_permission(dentry->d_inode, oflag2acc[oflag & O_ACCMODE])) { 644 dput(dentry); 645 mntput(mqueue_mnt); 646 return ERR_PTR(-EACCES); 647 } 648 649 return dentry_open(dentry, mqueue_mnt, oflag, cred); 650 } 651 652 asmlinkage long sys_mq_open(const char __user *u_name, int oflag, mode_t mode, 653 struct mq_attr __user *u_attr) 654 { 655 struct dentry *dentry; 656 struct file *filp; 657 char *name; 658 struct mq_attr attr; 659 int fd, error; 660 661 if (u_attr && copy_from_user(&attr, u_attr, sizeof(struct mq_attr))) 662 return -EFAULT; 663 664 audit_mq_open(oflag, mode, u_attr ? &attr : NULL); 665 666 if (IS_ERR(name = getname(u_name))) 667 return PTR_ERR(name); 668 669 fd = get_unused_fd_flags(O_CLOEXEC); 670 if (fd < 0) 671 goto out_putname; 672 673 mutex_lock(&mqueue_mnt->mnt_root->d_inode->i_mutex); 674 dentry = lookup_one_len(name, mqueue_mnt->mnt_root, strlen(name)); 675 if (IS_ERR(dentry)) { 676 error = PTR_ERR(dentry); 677 goto out_err; 678 } 679 mntget(mqueue_mnt); 680 681 if (oflag & O_CREAT) { 682 if (dentry->d_inode) { /* entry already exists */ 683 audit_inode(name, dentry); 684 error = -EEXIST; 685 if (oflag & O_EXCL) 686 goto out; 687 filp = do_open(dentry, oflag); 688 } else { 689 filp = do_create(mqueue_mnt->mnt_root, dentry, 690 oflag, mode, 691 u_attr ? &attr : NULL); 692 } 693 } else { 694 error = -ENOENT; 695 if (!dentry->d_inode) 696 goto out; 697 audit_inode(name, dentry); 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 fd_install(fd, filp); 707 goto out_upsem; 708 709 out: 710 dput(dentry); 711 mntput(mqueue_mnt); 712 out_putfd: 713 put_unused_fd(fd); 714 out_err: 715 fd = error; 716 out_upsem: 717 mutex_unlock(&mqueue_mnt->mnt_root->d_inode->i_mutex); 718 out_putname: 719 putname(name); 720 return fd; 721 } 722 723 asmlinkage long sys_mq_unlink(const char __user *u_name) 724 { 725 int err; 726 char *name; 727 struct dentry *dentry; 728 struct inode *inode = NULL; 729 730 name = getname(u_name); 731 if (IS_ERR(name)) 732 return PTR_ERR(name); 733 734 mutex_lock_nested(&mqueue_mnt->mnt_root->d_inode->i_mutex, 735 I_MUTEX_PARENT); 736 dentry = lookup_one_len(name, mqueue_mnt->mnt_root, strlen(name)); 737 if (IS_ERR(dentry)) { 738 err = PTR_ERR(dentry); 739 goto out_unlock; 740 } 741 742 if (!dentry->d_inode) { 743 err = -ENOENT; 744 goto out_err; 745 } 746 747 inode = dentry->d_inode; 748 if (inode) 749 atomic_inc(&inode->i_count); 750 err = mnt_want_write(mqueue_mnt); 751 if (err) 752 goto out_err; 753 err = vfs_unlink(dentry->d_parent->d_inode, dentry); 754 mnt_drop_write(mqueue_mnt); 755 out_err: 756 dput(dentry); 757 758 out_unlock: 759 mutex_unlock(&mqueue_mnt->mnt_root->d_inode->i_mutex); 760 putname(name); 761 if (inode) 762 iput(inode); 763 764 return err; 765 } 766 767 /* Pipelined send and receive functions. 768 * 769 * If a receiver finds no waiting message, then it registers itself in the 770 * list of waiting receivers. A sender checks that list before adding the new 771 * message into the message array. If there is a waiting receiver, then it 772 * bypasses the message array and directly hands the message over to the 773 * receiver. 774 * The receiver accepts the message and returns without grabbing the queue 775 * spinlock. Therefore an intermediate STATE_PENDING state and memory barriers 776 * are necessary. The same algorithm is used for sysv semaphores, see 777 * ipc/sem.c for more details. 778 * 779 * The same algorithm is used for senders. 780 */ 781 782 /* pipelined_send() - send a message directly to the task waiting in 783 * sys_mq_timedreceive() (without inserting message into a queue). 784 */ 785 static inline void pipelined_send(struct mqueue_inode_info *info, 786 struct msg_msg *message, 787 struct ext_wait_queue *receiver) 788 { 789 receiver->msg = message; 790 list_del(&receiver->list); 791 receiver->state = STATE_PENDING; 792 wake_up_process(receiver->task); 793 smp_wmb(); 794 receiver->state = STATE_READY; 795 } 796 797 /* pipelined_receive() - if there is task waiting in sys_mq_timedsend() 798 * gets its message and put to the queue (we have one free place for sure). */ 799 static inline void pipelined_receive(struct mqueue_inode_info *info) 800 { 801 struct ext_wait_queue *sender = wq_get_first_waiter(info, SEND); 802 803 if (!sender) { 804 /* for poll */ 805 wake_up_interruptible(&info->wait_q); 806 return; 807 } 808 msg_insert(sender->msg, info); 809 list_del(&sender->list); 810 sender->state = STATE_PENDING; 811 wake_up_process(sender->task); 812 smp_wmb(); 813 sender->state = STATE_READY; 814 } 815 816 asmlinkage long sys_mq_timedsend(mqd_t mqdes, const char __user *u_msg_ptr, 817 size_t msg_len, unsigned int msg_prio, 818 const struct timespec __user *u_abs_timeout) 819 { 820 struct file *filp; 821 struct inode *inode; 822 struct ext_wait_queue wait; 823 struct ext_wait_queue *receiver; 824 struct msg_msg *msg_ptr; 825 struct mqueue_inode_info *info; 826 struct timespec ts, *p = NULL; 827 long timeout; 828 int ret; 829 830 if (u_abs_timeout) { 831 if (copy_from_user(&ts, u_abs_timeout, 832 sizeof(struct timespec))) 833 return -EFAULT; 834 p = &ts; 835 } 836 837 if (unlikely(msg_prio >= (unsigned long) MQ_PRIO_MAX)) 838 return -EINVAL; 839 840 audit_mq_sendrecv(mqdes, msg_len, msg_prio, p); 841 timeout = prepare_timeout(p); 842 843 ret = -EBADF; 844 filp = fget(mqdes); 845 if (unlikely(!filp)) 846 goto out; 847 848 inode = filp->f_path.dentry->d_inode; 849 if (unlikely(filp->f_op != &mqueue_file_operations)) 850 goto out_fput; 851 info = MQUEUE_I(inode); 852 audit_inode(NULL, filp->f_path.dentry); 853 854 if (unlikely(!(filp->f_mode & FMODE_WRITE))) 855 goto out_fput; 856 857 if (unlikely(msg_len > info->attr.mq_msgsize)) { 858 ret = -EMSGSIZE; 859 goto out_fput; 860 } 861 862 /* First try to allocate memory, before doing anything with 863 * existing queues. */ 864 msg_ptr = load_msg(u_msg_ptr, msg_len); 865 if (IS_ERR(msg_ptr)) { 866 ret = PTR_ERR(msg_ptr); 867 goto out_fput; 868 } 869 msg_ptr->m_ts = msg_len; 870 msg_ptr->m_type = msg_prio; 871 872 spin_lock(&info->lock); 873 874 if (info->attr.mq_curmsgs == info->attr.mq_maxmsg) { 875 if (filp->f_flags & O_NONBLOCK) { 876 spin_unlock(&info->lock); 877 ret = -EAGAIN; 878 } else if (unlikely(timeout < 0)) { 879 spin_unlock(&info->lock); 880 ret = timeout; 881 } else { 882 wait.task = current; 883 wait.msg = (void *) msg_ptr; 884 wait.state = STATE_NONE; 885 ret = wq_sleep(info, SEND, timeout, &wait); 886 } 887 if (ret < 0) 888 free_msg(msg_ptr); 889 } else { 890 receiver = wq_get_first_waiter(info, RECV); 891 if (receiver) { 892 pipelined_send(info, msg_ptr, receiver); 893 } else { 894 /* adds message to the queue */ 895 msg_insert(msg_ptr, info); 896 __do_notify(info); 897 } 898 inode->i_atime = inode->i_mtime = inode->i_ctime = 899 CURRENT_TIME; 900 spin_unlock(&info->lock); 901 ret = 0; 902 } 903 out_fput: 904 fput(filp); 905 out: 906 return ret; 907 } 908 909 asmlinkage ssize_t sys_mq_timedreceive(mqd_t mqdes, char __user *u_msg_ptr, 910 size_t msg_len, unsigned int __user *u_msg_prio, 911 const struct timespec __user *u_abs_timeout) 912 { 913 long timeout; 914 ssize_t ret; 915 struct msg_msg *msg_ptr; 916 struct file *filp; 917 struct inode *inode; 918 struct mqueue_inode_info *info; 919 struct ext_wait_queue wait; 920 struct timespec ts, *p = NULL; 921 922 if (u_abs_timeout) { 923 if (copy_from_user(&ts, u_abs_timeout, 924 sizeof(struct timespec))) 925 return -EFAULT; 926 p = &ts; 927 } 928 929 audit_mq_sendrecv(mqdes, msg_len, 0, p); 930 timeout = prepare_timeout(p); 931 932 ret = -EBADF; 933 filp = fget(mqdes); 934 if (unlikely(!filp)) 935 goto out; 936 937 inode = filp->f_path.dentry->d_inode; 938 if (unlikely(filp->f_op != &mqueue_file_operations)) 939 goto out_fput; 940 info = MQUEUE_I(inode); 941 audit_inode(NULL, filp->f_path.dentry); 942 943 if (unlikely(!(filp->f_mode & FMODE_READ))) 944 goto out_fput; 945 946 /* checks if buffer is big enough */ 947 if (unlikely(msg_len < info->attr.mq_msgsize)) { 948 ret = -EMSGSIZE; 949 goto out_fput; 950 } 951 952 spin_lock(&info->lock); 953 if (info->attr.mq_curmsgs == 0) { 954 if (filp->f_flags & O_NONBLOCK) { 955 spin_unlock(&info->lock); 956 ret = -EAGAIN; 957 msg_ptr = NULL; 958 } else if (unlikely(timeout < 0)) { 959 spin_unlock(&info->lock); 960 ret = timeout; 961 msg_ptr = NULL; 962 } else { 963 wait.task = current; 964 wait.state = STATE_NONE; 965 ret = wq_sleep(info, RECV, timeout, &wait); 966 msg_ptr = wait.msg; 967 } 968 } else { 969 msg_ptr = msg_get(info); 970 971 inode->i_atime = inode->i_mtime = inode->i_ctime = 972 CURRENT_TIME; 973 974 /* There is now free space in queue. */ 975 pipelined_receive(info); 976 spin_unlock(&info->lock); 977 ret = 0; 978 } 979 if (ret == 0) { 980 ret = msg_ptr->m_ts; 981 982 if ((u_msg_prio && put_user(msg_ptr->m_type, u_msg_prio)) || 983 store_msg(u_msg_ptr, msg_ptr, msg_ptr->m_ts)) { 984 ret = -EFAULT; 985 } 986 free_msg(msg_ptr); 987 } 988 out_fput: 989 fput(filp); 990 out: 991 return ret; 992 } 993 994 /* 995 * Notes: the case when user wants us to deregister (with NULL as pointer) 996 * and he isn't currently owner of notification, will be silently discarded. 997 * It isn't explicitly defined in the POSIX. 998 */ 999 asmlinkage long sys_mq_notify(mqd_t mqdes, 1000 const struct sigevent __user *u_notification) 1001 { 1002 int ret; 1003 struct file *filp; 1004 struct sock *sock; 1005 struct inode *inode; 1006 struct sigevent notification; 1007 struct mqueue_inode_info *info; 1008 struct sk_buff *nc; 1009 1010 if (u_notification) { 1011 if (copy_from_user(¬ification, u_notification, 1012 sizeof(struct sigevent))) 1013 return -EFAULT; 1014 } 1015 1016 audit_mq_notify(mqdes, u_notification ? ¬ification : NULL); 1017 1018 nc = NULL; 1019 sock = NULL; 1020 if (u_notification != NULL) { 1021 if (unlikely(notification.sigev_notify != SIGEV_NONE && 1022 notification.sigev_notify != SIGEV_SIGNAL && 1023 notification.sigev_notify != SIGEV_THREAD)) 1024 return -EINVAL; 1025 if (notification.sigev_notify == SIGEV_SIGNAL && 1026 !valid_signal(notification.sigev_signo)) { 1027 return -EINVAL; 1028 } 1029 if (notification.sigev_notify == SIGEV_THREAD) { 1030 long timeo; 1031 1032 /* create the notify skb */ 1033 nc = alloc_skb(NOTIFY_COOKIE_LEN, GFP_KERNEL); 1034 ret = -ENOMEM; 1035 if (!nc) 1036 goto out; 1037 ret = -EFAULT; 1038 if (copy_from_user(nc->data, 1039 notification.sigev_value.sival_ptr, 1040 NOTIFY_COOKIE_LEN)) { 1041 goto out; 1042 } 1043 1044 /* TODO: add a header? */ 1045 skb_put(nc, NOTIFY_COOKIE_LEN); 1046 /* and attach it to the socket */ 1047 retry: 1048 filp = fget(notification.sigev_signo); 1049 ret = -EBADF; 1050 if (!filp) 1051 goto out; 1052 sock = netlink_getsockbyfilp(filp); 1053 fput(filp); 1054 if (IS_ERR(sock)) { 1055 ret = PTR_ERR(sock); 1056 sock = NULL; 1057 goto out; 1058 } 1059 1060 timeo = MAX_SCHEDULE_TIMEOUT; 1061 ret = netlink_attachskb(sock, nc, &timeo, NULL); 1062 if (ret == 1) 1063 goto retry; 1064 if (ret) { 1065 sock = NULL; 1066 nc = NULL; 1067 goto out; 1068 } 1069 } 1070 } 1071 1072 ret = -EBADF; 1073 filp = fget(mqdes); 1074 if (!filp) 1075 goto out; 1076 1077 inode = filp->f_path.dentry->d_inode; 1078 if (unlikely(filp->f_op != &mqueue_file_operations)) 1079 goto out_fput; 1080 info = MQUEUE_I(inode); 1081 1082 ret = 0; 1083 spin_lock(&info->lock); 1084 if (u_notification == NULL) { 1085 if (info->notify_owner == task_tgid(current)) { 1086 remove_notification(info); 1087 inode->i_atime = inode->i_ctime = CURRENT_TIME; 1088 } 1089 } else if (info->notify_owner != NULL) { 1090 ret = -EBUSY; 1091 } else { 1092 switch (notification.sigev_notify) { 1093 case SIGEV_NONE: 1094 info->notify.sigev_notify = SIGEV_NONE; 1095 break; 1096 case SIGEV_THREAD: 1097 info->notify_sock = sock; 1098 info->notify_cookie = nc; 1099 sock = NULL; 1100 nc = NULL; 1101 info->notify.sigev_notify = SIGEV_THREAD; 1102 break; 1103 case SIGEV_SIGNAL: 1104 info->notify.sigev_signo = notification.sigev_signo; 1105 info->notify.sigev_value = notification.sigev_value; 1106 info->notify.sigev_notify = SIGEV_SIGNAL; 1107 break; 1108 } 1109 1110 info->notify_owner = get_pid(task_tgid(current)); 1111 inode->i_atime = inode->i_ctime = CURRENT_TIME; 1112 } 1113 spin_unlock(&info->lock); 1114 out_fput: 1115 fput(filp); 1116 out: 1117 if (sock) { 1118 netlink_detachskb(sock, nc); 1119 } else if (nc) { 1120 dev_kfree_skb(nc); 1121 } 1122 return ret; 1123 } 1124 1125 asmlinkage long sys_mq_getsetattr(mqd_t mqdes, 1126 const struct mq_attr __user *u_mqstat, 1127 struct mq_attr __user *u_omqstat) 1128 { 1129 int ret; 1130 struct mq_attr mqstat, omqstat; 1131 struct file *filp; 1132 struct inode *inode; 1133 struct mqueue_inode_info *info; 1134 1135 if (u_mqstat != NULL) { 1136 if (copy_from_user(&mqstat, u_mqstat, sizeof(struct mq_attr))) 1137 return -EFAULT; 1138 if (mqstat.mq_flags & (~O_NONBLOCK)) 1139 return -EINVAL; 1140 } 1141 1142 ret = -EBADF; 1143 filp = fget(mqdes); 1144 if (!filp) 1145 goto out; 1146 1147 inode = filp->f_path.dentry->d_inode; 1148 if (unlikely(filp->f_op != &mqueue_file_operations)) 1149 goto out_fput; 1150 info = MQUEUE_I(inode); 1151 1152 spin_lock(&info->lock); 1153 1154 omqstat = info->attr; 1155 omqstat.mq_flags = filp->f_flags & O_NONBLOCK; 1156 if (u_mqstat) { 1157 audit_mq_getsetattr(mqdes, &mqstat); 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 = MIN_MSGMAX; 1206 static int msg_max_limit_max = MAX_MSGMAX; 1207 1208 static int msg_maxsize_limit_min = MIN_MSGSIZEMAX; 1209 static int msg_maxsize_limit_max = MAX_MSGSIZEMAX; 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