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 * 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_nr_ns(current, 509 ns_of_pid(info->notify_owner)); 510 sig_i.si_uid = current_uid(); 511 512 kill_pid_info(info->notify.sigev_signo, 513 &sig_i, info->notify_owner); 514 break; 515 case SIGEV_THREAD: 516 set_cookie(info->notify_cookie, NOTIFY_WOKENUP); 517 netlink_sendskb(info->notify_sock, info->notify_cookie); 518 break; 519 } 520 /* after notification unregisters process */ 521 put_pid(info->notify_owner); 522 info->notify_owner = NULL; 523 } 524 wake_up(&info->wait_q); 525 } 526 527 static long prepare_timeout(struct timespec *p) 528 { 529 struct timespec nowts; 530 long timeout; 531 532 if (p) { 533 if (unlikely(p->tv_nsec < 0 || p->tv_sec < 0 534 || p->tv_nsec >= NSEC_PER_SEC)) 535 return -EINVAL; 536 nowts = CURRENT_TIME; 537 /* first subtract as jiffies can't be too big */ 538 p->tv_sec -= nowts.tv_sec; 539 if (p->tv_nsec < nowts.tv_nsec) { 540 p->tv_nsec += NSEC_PER_SEC; 541 p->tv_sec--; 542 } 543 p->tv_nsec -= nowts.tv_nsec; 544 if (p->tv_sec < 0) 545 return 0; 546 547 timeout = timespec_to_jiffies(p) + 1; 548 } else 549 return MAX_SCHEDULE_TIMEOUT; 550 551 return timeout; 552 } 553 554 static void remove_notification(struct mqueue_inode_info *info) 555 { 556 if (info->notify_owner != NULL && 557 info->notify.sigev_notify == SIGEV_THREAD) { 558 set_cookie(info->notify_cookie, NOTIFY_REMOVED); 559 netlink_sendskb(info->notify_sock, info->notify_cookie); 560 } 561 put_pid(info->notify_owner); 562 info->notify_owner = NULL; 563 } 564 565 static int mq_attr_ok(struct mq_attr *attr) 566 { 567 if (attr->mq_maxmsg <= 0 || attr->mq_msgsize <= 0) 568 return 0; 569 if (capable(CAP_SYS_RESOURCE)) { 570 if (attr->mq_maxmsg > HARD_MSGMAX) 571 return 0; 572 } else { 573 if (attr->mq_maxmsg > msg_max || 574 attr->mq_msgsize > msgsize_max) 575 return 0; 576 } 577 /* check for overflow */ 578 if (attr->mq_msgsize > ULONG_MAX/attr->mq_maxmsg) 579 return 0; 580 if ((unsigned long)(attr->mq_maxmsg * attr->mq_msgsize) + 581 (attr->mq_maxmsg * sizeof (struct msg_msg *)) < 582 (unsigned long)(attr->mq_maxmsg * attr->mq_msgsize)) 583 return 0; 584 return 1; 585 } 586 587 /* 588 * Invoked when creating a new queue via sys_mq_open 589 */ 590 static struct file *do_create(struct dentry *dir, struct dentry *dentry, 591 int oflag, mode_t mode, struct mq_attr *attr) 592 { 593 const struct cred *cred = current_cred(); 594 struct file *result; 595 int ret; 596 597 if (attr) { 598 ret = -EINVAL; 599 if (!mq_attr_ok(attr)) 600 goto out; 601 /* store for use during create */ 602 dentry->d_fsdata = attr; 603 } 604 605 mode &= ~current->fs->umask; 606 ret = mnt_want_write(mqueue_mnt); 607 if (ret) 608 goto out; 609 ret = vfs_create(dir->d_inode, dentry, mode, NULL); 610 dentry->d_fsdata = NULL; 611 if (ret) 612 goto out_drop_write; 613 614 result = dentry_open(dentry, mqueue_mnt, oflag, cred); 615 /* 616 * dentry_open() took a persistent mnt_want_write(), 617 * so we can now drop this one. 618 */ 619 mnt_drop_write(mqueue_mnt); 620 return result; 621 622 out_drop_write: 623 mnt_drop_write(mqueue_mnt); 624 out: 625 dput(dentry); 626 mntput(mqueue_mnt); 627 return ERR_PTR(ret); 628 } 629 630 /* Opens existing queue */ 631 static struct file *do_open(struct dentry *dentry, int oflag) 632 { 633 const struct cred *cred = current_cred(); 634 635 static const int oflag2acc[O_ACCMODE] = { MAY_READ, MAY_WRITE, 636 MAY_READ | MAY_WRITE }; 637 638 if ((oflag & O_ACCMODE) == (O_RDWR | O_WRONLY)) { 639 dput(dentry); 640 mntput(mqueue_mnt); 641 return ERR_PTR(-EINVAL); 642 } 643 644 if (inode_permission(dentry->d_inode, oflag2acc[oflag & O_ACCMODE])) { 645 dput(dentry); 646 mntput(mqueue_mnt); 647 return ERR_PTR(-EACCES); 648 } 649 650 return dentry_open(dentry, mqueue_mnt, oflag, cred); 651 } 652 653 SYSCALL_DEFINE4(mq_open, const char __user *, u_name, int, oflag, mode_t, mode, 654 struct mq_attr __user *, u_attr) 655 { 656 struct dentry *dentry; 657 struct file *filp; 658 char *name; 659 struct mq_attr attr; 660 int fd, error; 661 662 if (u_attr && copy_from_user(&attr, u_attr, sizeof(struct mq_attr))) 663 return -EFAULT; 664 665 audit_mq_open(oflag, mode, u_attr ? &attr : NULL); 666 667 if (IS_ERR(name = getname(u_name))) 668 return PTR_ERR(name); 669 670 fd = get_unused_fd_flags(O_CLOEXEC); 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); 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, 692 u_attr ? &attr : NULL); 693 } 694 } else { 695 error = -ENOENT; 696 if (!dentry->d_inode) 697 goto out; 698 audit_inode(name, dentry); 699 filp = do_open(dentry, oflag); 700 } 701 702 if (IS_ERR(filp)) { 703 error = PTR_ERR(filp); 704 goto out_putfd; 705 } 706 707 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 SYSCALL_DEFINE1(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 err = mnt_want_write(mqueue_mnt); 752 if (err) 753 goto out_err; 754 err = vfs_unlink(dentry->d_parent->d_inode, dentry); 755 mnt_drop_write(mqueue_mnt); 756 out_err: 757 dput(dentry); 758 759 out_unlock: 760 mutex_unlock(&mqueue_mnt->mnt_root->d_inode->i_mutex); 761 putname(name); 762 if (inode) 763 iput(inode); 764 765 return err; 766 } 767 768 /* Pipelined send and receive functions. 769 * 770 * If a receiver finds no waiting message, then it registers itself in the 771 * list of waiting receivers. A sender checks that list before adding the new 772 * message into the message array. If there is a waiting receiver, then it 773 * bypasses the message array and directly hands the message over to the 774 * receiver. 775 * The receiver accepts the message and returns without grabbing the queue 776 * spinlock. Therefore an intermediate STATE_PENDING state and memory barriers 777 * are necessary. The same algorithm is used for sysv semaphores, see 778 * ipc/sem.c for more details. 779 * 780 * The same algorithm is used for senders. 781 */ 782 783 /* pipelined_send() - send a message directly to the task waiting in 784 * sys_mq_timedreceive() (without inserting message into a queue). 785 */ 786 static inline void pipelined_send(struct mqueue_inode_info *info, 787 struct msg_msg *message, 788 struct ext_wait_queue *receiver) 789 { 790 receiver->msg = message; 791 list_del(&receiver->list); 792 receiver->state = STATE_PENDING; 793 wake_up_process(receiver->task); 794 smp_wmb(); 795 receiver->state = STATE_READY; 796 } 797 798 /* pipelined_receive() - if there is task waiting in sys_mq_timedsend() 799 * gets its message and put to the queue (we have one free place for sure). */ 800 static inline void pipelined_receive(struct mqueue_inode_info *info) 801 { 802 struct ext_wait_queue *sender = wq_get_first_waiter(info, SEND); 803 804 if (!sender) { 805 /* for poll */ 806 wake_up_interruptible(&info->wait_q); 807 return; 808 } 809 msg_insert(sender->msg, info); 810 list_del(&sender->list); 811 sender->state = STATE_PENDING; 812 wake_up_process(sender->task); 813 smp_wmb(); 814 sender->state = STATE_READY; 815 } 816 817 SYSCALL_DEFINE5(mq_timedsend, mqd_t, mqdes, const char __user *, u_msg_ptr, 818 size_t, msg_len, unsigned int, msg_prio, 819 const struct timespec __user *, u_abs_timeout) 820 { 821 struct file *filp; 822 struct inode *inode; 823 struct ext_wait_queue wait; 824 struct ext_wait_queue *receiver; 825 struct msg_msg *msg_ptr; 826 struct mqueue_inode_info *info; 827 struct timespec ts, *p = NULL; 828 long timeout; 829 int ret; 830 831 if (u_abs_timeout) { 832 if (copy_from_user(&ts, u_abs_timeout, 833 sizeof(struct timespec))) 834 return -EFAULT; 835 p = &ts; 836 } 837 838 if (unlikely(msg_prio >= (unsigned long) MQ_PRIO_MAX)) 839 return -EINVAL; 840 841 audit_mq_sendrecv(mqdes, msg_len, msg_prio, p); 842 timeout = prepare_timeout(p); 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 SYSCALL_DEFINE5(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 struct timespec ts, *p = NULL; 922 923 if (u_abs_timeout) { 924 if (copy_from_user(&ts, u_abs_timeout, 925 sizeof(struct timespec))) 926 return -EFAULT; 927 p = &ts; 928 } 929 930 audit_mq_sendrecv(mqdes, msg_len, 0, p); 931 timeout = prepare_timeout(p); 932 933 ret = -EBADF; 934 filp = fget(mqdes); 935 if (unlikely(!filp)) 936 goto out; 937 938 inode = filp->f_path.dentry->d_inode; 939 if (unlikely(filp->f_op != &mqueue_file_operations)) 940 goto out_fput; 941 info = MQUEUE_I(inode); 942 audit_inode(NULL, filp->f_path.dentry); 943 944 if (unlikely(!(filp->f_mode & FMODE_READ))) 945 goto out_fput; 946 947 /* checks if buffer is big enough */ 948 if (unlikely(msg_len < info->attr.mq_msgsize)) { 949 ret = -EMSGSIZE; 950 goto out_fput; 951 } 952 953 spin_lock(&info->lock); 954 if (info->attr.mq_curmsgs == 0) { 955 if (filp->f_flags & O_NONBLOCK) { 956 spin_unlock(&info->lock); 957 ret = -EAGAIN; 958 msg_ptr = NULL; 959 } else if (unlikely(timeout < 0)) { 960 spin_unlock(&info->lock); 961 ret = timeout; 962 msg_ptr = NULL; 963 } else { 964 wait.task = current; 965 wait.state = STATE_NONE; 966 ret = wq_sleep(info, RECV, timeout, &wait); 967 msg_ptr = wait.msg; 968 } 969 } else { 970 msg_ptr = msg_get(info); 971 972 inode->i_atime = inode->i_mtime = inode->i_ctime = 973 CURRENT_TIME; 974 975 /* There is now free space in queue. */ 976 pipelined_receive(info); 977 spin_unlock(&info->lock); 978 ret = 0; 979 } 980 if (ret == 0) { 981 ret = msg_ptr->m_ts; 982 983 if ((u_msg_prio && put_user(msg_ptr->m_type, u_msg_prio)) || 984 store_msg(u_msg_ptr, msg_ptr, msg_ptr->m_ts)) { 985 ret = -EFAULT; 986 } 987 free_msg(msg_ptr); 988 } 989 out_fput: 990 fput(filp); 991 out: 992 return ret; 993 } 994 995 /* 996 * Notes: the case when user wants us to deregister (with NULL as pointer) 997 * and he isn't currently owner of notification, will be silently discarded. 998 * It isn't explicitly defined in the POSIX. 999 */ 1000 SYSCALL_DEFINE2(mq_notify, mqd_t, mqdes, 1001 const struct sigevent __user *, u_notification) 1002 { 1003 int ret; 1004 struct file *filp; 1005 struct sock *sock; 1006 struct inode *inode; 1007 struct sigevent notification; 1008 struct mqueue_inode_info *info; 1009 struct sk_buff *nc; 1010 1011 if (u_notification) { 1012 if (copy_from_user(¬ification, u_notification, 1013 sizeof(struct sigevent))) 1014 return -EFAULT; 1015 } 1016 1017 audit_mq_notify(mqdes, u_notification ? ¬ification : NULL); 1018 1019 nc = NULL; 1020 sock = NULL; 1021 if (u_notification != NULL) { 1022 if (unlikely(notification.sigev_notify != SIGEV_NONE && 1023 notification.sigev_notify != SIGEV_SIGNAL && 1024 notification.sigev_notify != SIGEV_THREAD)) 1025 return -EINVAL; 1026 if (notification.sigev_notify == SIGEV_SIGNAL && 1027 !valid_signal(notification.sigev_signo)) { 1028 return -EINVAL; 1029 } 1030 if (notification.sigev_notify == SIGEV_THREAD) { 1031 long timeo; 1032 1033 /* create the notify skb */ 1034 nc = alloc_skb(NOTIFY_COOKIE_LEN, GFP_KERNEL); 1035 ret = -ENOMEM; 1036 if (!nc) 1037 goto out; 1038 ret = -EFAULT; 1039 if (copy_from_user(nc->data, 1040 notification.sigev_value.sival_ptr, 1041 NOTIFY_COOKIE_LEN)) { 1042 goto out; 1043 } 1044 1045 /* TODO: add a header? */ 1046 skb_put(nc, NOTIFY_COOKIE_LEN); 1047 /* and attach it to the socket */ 1048 retry: 1049 filp = fget(notification.sigev_signo); 1050 ret = -EBADF; 1051 if (!filp) 1052 goto out; 1053 sock = netlink_getsockbyfilp(filp); 1054 fput(filp); 1055 if (IS_ERR(sock)) { 1056 ret = PTR_ERR(sock); 1057 sock = NULL; 1058 goto out; 1059 } 1060 1061 timeo = MAX_SCHEDULE_TIMEOUT; 1062 ret = netlink_attachskb(sock, nc, &timeo, NULL); 1063 if (ret == 1) 1064 goto retry; 1065 if (ret) { 1066 sock = NULL; 1067 nc = NULL; 1068 goto out; 1069 } 1070 } 1071 } 1072 1073 ret = -EBADF; 1074 filp = fget(mqdes); 1075 if (!filp) 1076 goto out; 1077 1078 inode = filp->f_path.dentry->d_inode; 1079 if (unlikely(filp->f_op != &mqueue_file_operations)) 1080 goto out_fput; 1081 info = MQUEUE_I(inode); 1082 1083 ret = 0; 1084 spin_lock(&info->lock); 1085 if (u_notification == NULL) { 1086 if (info->notify_owner == task_tgid(current)) { 1087 remove_notification(info); 1088 inode->i_atime = inode->i_ctime = CURRENT_TIME; 1089 } 1090 } else if (info->notify_owner != NULL) { 1091 ret = -EBUSY; 1092 } else { 1093 switch (notification.sigev_notify) { 1094 case SIGEV_NONE: 1095 info->notify.sigev_notify = SIGEV_NONE; 1096 break; 1097 case SIGEV_THREAD: 1098 info->notify_sock = sock; 1099 info->notify_cookie = nc; 1100 sock = NULL; 1101 nc = NULL; 1102 info->notify.sigev_notify = SIGEV_THREAD; 1103 break; 1104 case SIGEV_SIGNAL: 1105 info->notify.sigev_signo = notification.sigev_signo; 1106 info->notify.sigev_value = notification.sigev_value; 1107 info->notify.sigev_notify = SIGEV_SIGNAL; 1108 break; 1109 } 1110 1111 info->notify_owner = get_pid(task_tgid(current)); 1112 inode->i_atime = inode->i_ctime = CURRENT_TIME; 1113 } 1114 spin_unlock(&info->lock); 1115 out_fput: 1116 fput(filp); 1117 out: 1118 if (sock) { 1119 netlink_detachskb(sock, nc); 1120 } else if (nc) { 1121 dev_kfree_skb(nc); 1122 } 1123 return ret; 1124 } 1125 1126 SYSCALL_DEFINE3(mq_getsetattr, mqd_t, mqdes, 1127 const struct mq_attr __user *, u_mqstat, 1128 struct mq_attr __user *, u_omqstat) 1129 { 1130 int ret; 1131 struct mq_attr mqstat, omqstat; 1132 struct file *filp; 1133 struct inode *inode; 1134 struct mqueue_inode_info *info; 1135 1136 if (u_mqstat != NULL) { 1137 if (copy_from_user(&mqstat, u_mqstat, sizeof(struct mq_attr))) 1138 return -EFAULT; 1139 if (mqstat.mq_flags & (~O_NONBLOCK)) 1140 return -EINVAL; 1141 } 1142 1143 ret = -EBADF; 1144 filp = fget(mqdes); 1145 if (!filp) 1146 goto out; 1147 1148 inode = filp->f_path.dentry->d_inode; 1149 if (unlikely(filp->f_op != &mqueue_file_operations)) 1150 goto out_fput; 1151 info = MQUEUE_I(inode); 1152 1153 spin_lock(&info->lock); 1154 1155 omqstat = info->attr; 1156 omqstat.mq_flags = filp->f_flags & O_NONBLOCK; 1157 if (u_mqstat) { 1158 audit_mq_getsetattr(mqdes, &mqstat); 1159 spin_lock(&filp->f_lock); 1160 if (mqstat.mq_flags & O_NONBLOCK) 1161 filp->f_flags |= O_NONBLOCK; 1162 else 1163 filp->f_flags &= ~O_NONBLOCK; 1164 spin_unlock(&filp->f_lock); 1165 1166 inode->i_atime = inode->i_ctime = CURRENT_TIME; 1167 } 1168 1169 spin_unlock(&info->lock); 1170 1171 ret = 0; 1172 if (u_omqstat != NULL && copy_to_user(u_omqstat, &omqstat, 1173 sizeof(struct mq_attr))) 1174 ret = -EFAULT; 1175 1176 out_fput: 1177 fput(filp); 1178 out: 1179 return ret; 1180 } 1181 1182 static const struct inode_operations mqueue_dir_inode_operations = { 1183 .lookup = simple_lookup, 1184 .create = mqueue_create, 1185 .unlink = mqueue_unlink, 1186 }; 1187 1188 static const struct file_operations mqueue_file_operations = { 1189 .flush = mqueue_flush_file, 1190 .poll = mqueue_poll_file, 1191 .read = mqueue_read_file, 1192 }; 1193 1194 static struct super_operations mqueue_super_ops = { 1195 .alloc_inode = mqueue_alloc_inode, 1196 .destroy_inode = mqueue_destroy_inode, 1197 .statfs = simple_statfs, 1198 .delete_inode = mqueue_delete_inode, 1199 .drop_inode = generic_delete_inode, 1200 }; 1201 1202 static struct file_system_type mqueue_fs_type = { 1203 .name = "mqueue", 1204 .get_sb = mqueue_get_sb, 1205 .kill_sb = kill_litter_super, 1206 }; 1207 1208 static int msg_max_limit_min = MIN_MSGMAX; 1209 static int msg_max_limit_max = MAX_MSGMAX; 1210 1211 static int msg_maxsize_limit_min = MIN_MSGSIZEMAX; 1212 static int msg_maxsize_limit_max = MAX_MSGSIZEMAX; 1213 1214 static ctl_table mq_sysctls[] = { 1215 { 1216 .procname = "queues_max", 1217 .data = &queues_max, 1218 .maxlen = sizeof(int), 1219 .mode = 0644, 1220 .proc_handler = &proc_dointvec, 1221 }, 1222 { 1223 .procname = "msg_max", 1224 .data = &msg_max, 1225 .maxlen = sizeof(int), 1226 .mode = 0644, 1227 .proc_handler = &proc_dointvec_minmax, 1228 .extra1 = &msg_max_limit_min, 1229 .extra2 = &msg_max_limit_max, 1230 }, 1231 { 1232 .procname = "msgsize_max", 1233 .data = &msgsize_max, 1234 .maxlen = sizeof(int), 1235 .mode = 0644, 1236 .proc_handler = &proc_dointvec_minmax, 1237 .extra1 = &msg_maxsize_limit_min, 1238 .extra2 = &msg_maxsize_limit_max, 1239 }, 1240 { .ctl_name = 0 } 1241 }; 1242 1243 static ctl_table mq_sysctl_dir[] = { 1244 { 1245 .procname = "mqueue", 1246 .mode = 0555, 1247 .child = mq_sysctls, 1248 }, 1249 { .ctl_name = 0 } 1250 }; 1251 1252 static ctl_table mq_sysctl_root[] = { 1253 { 1254 .ctl_name = CTL_FS, 1255 .procname = "fs", 1256 .mode = 0555, 1257 .child = mq_sysctl_dir, 1258 }, 1259 { .ctl_name = 0 } 1260 }; 1261 1262 static int __init init_mqueue_fs(void) 1263 { 1264 int error; 1265 1266 mqueue_inode_cachep = kmem_cache_create("mqueue_inode_cache", 1267 sizeof(struct mqueue_inode_info), 0, 1268 SLAB_HWCACHE_ALIGN, init_once); 1269 if (mqueue_inode_cachep == NULL) 1270 return -ENOMEM; 1271 1272 /* ignore failues - they are not fatal */ 1273 mq_sysctl_table = register_sysctl_table(mq_sysctl_root); 1274 1275 error = register_filesystem(&mqueue_fs_type); 1276 if (error) 1277 goto out_sysctl; 1278 1279 if (IS_ERR(mqueue_mnt = kern_mount(&mqueue_fs_type))) { 1280 error = PTR_ERR(mqueue_mnt); 1281 goto out_filesystem; 1282 } 1283 1284 /* internal initialization - not common for vfs */ 1285 queues_count = 0; 1286 spin_lock_init(&mq_lock); 1287 1288 return 0; 1289 1290 out_filesystem: 1291 unregister_filesystem(&mqueue_fs_type); 1292 out_sysctl: 1293 if (mq_sysctl_table) 1294 unregister_sysctl_table(mq_sysctl_table); 1295 kmem_cache_destroy(mqueue_inode_cachep); 1296 return error; 1297 } 1298 1299 __initcall(init_mqueue_fs); 1300