mqueue.c revision 75e1fcc0b18df0a65ab113198e9dc0e98999a08c
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@motorola.com) 6 * 7 * Spinlocks: Mohamed Abbas (abbas.mohamed@intel.com) 8 * Lockless receive & send, fd based notify: 9 * Manfred Spraul (manfred@colorfullife.com) 10 * 11 * Audit: George Wilson (ltcgcw@us.ibm.com) 12 * 13 * This file is released under the GPL. 14 */ 15 16#include <linux/capability.h> 17#include <linux/init.h> 18#include <linux/pagemap.h> 19#include <linux/file.h> 20#include <linux/mount.h> 21#include <linux/namei.h> 22#include <linux/sysctl.h> 23#include <linux/poll.h> 24#include <linux/mqueue.h> 25#include <linux/msg.h> 26#include <linux/skbuff.h> 27#include <linux/netlink.h> 28#include <linux/syscalls.h> 29#include <linux/audit.h> 30#include <linux/signal.h> 31#include <linux/mutex.h> 32 33#include <net/sock.h> 34#include "util.h" 35 36#define MQUEUE_MAGIC 0x19800202 37#define DIRENT_SIZE 20 38#define FILENT_SIZE 80 39 40#define SEND 0 41#define RECV 1 42 43#define STATE_NONE 0 44#define STATE_PENDING 1 45#define STATE_READY 2 46 47/* used by sysctl */ 48#define FS_MQUEUE 1 49#define CTL_QUEUESMAX 2 50#define CTL_MSGMAX 3 51#define CTL_MSGSIZEMAX 4 52 53/* default values */ 54#define DFLT_QUEUESMAX 256 /* max number of message queues */ 55#define DFLT_MSGMAX 10 /* max number of messages in each queue */ 56#define HARD_MSGMAX (131072/sizeof(void*)) 57#define DFLT_MSGSIZEMAX 8192 /* max message size */ 58 59 60struct ext_wait_queue { /* queue of sleeping tasks */ 61 struct task_struct *task; 62 struct list_head list; 63 struct msg_msg *msg; /* ptr of loaded message */ 64 int state; /* one of STATE_* values */ 65}; 66 67struct mqueue_inode_info { 68 spinlock_t lock; 69 struct inode vfs_inode; 70 wait_queue_head_t wait_q; 71 72 struct msg_msg **messages; 73 struct mq_attr attr; 74 75 struct sigevent notify; 76 pid_t notify_owner; 77 struct user_struct *user; /* user who created, for accounting */ 78 struct sock *notify_sock; 79 struct sk_buff *notify_cookie; 80 81 /* for tasks waiting for free space and messages, respectively */ 82 struct ext_wait_queue e_wait_q[2]; 83 84 unsigned long qsize; /* size of queue in memory (sum of all msgs) */ 85}; 86 87static struct inode_operations mqueue_dir_inode_operations; 88static struct file_operations mqueue_file_operations; 89static struct super_operations mqueue_super_ops; 90static void remove_notification(struct mqueue_inode_info *info); 91 92static spinlock_t mq_lock; 93static kmem_cache_t *mqueue_inode_cachep; 94static struct vfsmount *mqueue_mnt; 95 96static unsigned int queues_count; 97static unsigned int queues_max = DFLT_QUEUESMAX; 98static unsigned int msg_max = DFLT_MSGMAX; 99static unsigned int msgsize_max = DFLT_MSGSIZEMAX; 100 101static struct ctl_table_header * mq_sysctl_table; 102 103static inline struct mqueue_inode_info *MQUEUE_I(struct inode *inode) 104{ 105 return container_of(inode, struct mqueue_inode_info, vfs_inode); 106} 107 108static struct inode *mqueue_get_inode(struct super_block *sb, int mode, 109 struct mq_attr *attr) 110{ 111 struct inode *inode; 112 113 inode = new_inode(sb); 114 if (inode) { 115 inode->i_mode = mode; 116 inode->i_uid = current->fsuid; 117 inode->i_gid = current->fsgid; 118 inode->i_blksize = PAGE_CACHE_SIZE; 119 inode->i_blocks = 0; 120 inode->i_mtime = inode->i_ctime = inode->i_atime = 121 CURRENT_TIME; 122 123 if (S_ISREG(mode)) { 124 struct mqueue_inode_info *info; 125 struct task_struct *p = current; 126 struct user_struct *u = p->user; 127 unsigned long mq_bytes, mq_msg_tblsz; 128 129 inode->i_fop = &mqueue_file_operations; 130 inode->i_size = FILENT_SIZE; 131 /* mqueue specific info */ 132 info = MQUEUE_I(inode); 133 spin_lock_init(&info->lock); 134 init_waitqueue_head(&info->wait_q); 135 INIT_LIST_HEAD(&info->e_wait_q[0].list); 136 INIT_LIST_HEAD(&info->e_wait_q[1].list); 137 info->messages = NULL; 138 info->notify_owner = 0; 139 info->qsize = 0; 140 info->user = NULL; /* set when all is ok */ 141 memset(&info->attr, 0, sizeof(info->attr)); 142 info->attr.mq_maxmsg = DFLT_MSGMAX; 143 info->attr.mq_msgsize = DFLT_MSGSIZEMAX; 144 if (attr) { 145 info->attr.mq_maxmsg = attr->mq_maxmsg; 146 info->attr.mq_msgsize = attr->mq_msgsize; 147 } 148 mq_msg_tblsz = info->attr.mq_maxmsg * sizeof(struct msg_msg *); 149 mq_bytes = (mq_msg_tblsz + 150 (info->attr.mq_maxmsg * info->attr.mq_msgsize)); 151 152 spin_lock(&mq_lock); 153 if (u->mq_bytes + mq_bytes < u->mq_bytes || 154 u->mq_bytes + mq_bytes > 155 p->signal->rlim[RLIMIT_MSGQUEUE].rlim_cur) { 156 spin_unlock(&mq_lock); 157 goto out_inode; 158 } 159 u->mq_bytes += mq_bytes; 160 spin_unlock(&mq_lock); 161 162 info->messages = kmalloc(mq_msg_tblsz, GFP_KERNEL); 163 if (!info->messages) { 164 spin_lock(&mq_lock); 165 u->mq_bytes -= mq_bytes; 166 spin_unlock(&mq_lock); 167 goto out_inode; 168 } 169 /* all is ok */ 170 info->user = get_uid(u); 171 } else if (S_ISDIR(mode)) { 172 inode->i_nlink++; 173 /* Some things misbehave if size == 0 on a directory */ 174 inode->i_size = 2 * DIRENT_SIZE; 175 inode->i_op = &mqueue_dir_inode_operations; 176 inode->i_fop = &simple_dir_operations; 177 } 178 } 179 return inode; 180out_inode: 181 make_bad_inode(inode); 182 iput(inode); 183 return NULL; 184} 185 186static int mqueue_fill_super(struct super_block *sb, void *data, int silent) 187{ 188 struct inode *inode; 189 190 sb->s_blocksize = PAGE_CACHE_SIZE; 191 sb->s_blocksize_bits = PAGE_CACHE_SHIFT; 192 sb->s_magic = MQUEUE_MAGIC; 193 sb->s_op = &mqueue_super_ops; 194 195 inode = mqueue_get_inode(sb, S_IFDIR | S_ISVTX | S_IRWXUGO, NULL); 196 if (!inode) 197 return -ENOMEM; 198 199 sb->s_root = d_alloc_root(inode); 200 if (!sb->s_root) { 201 iput(inode); 202 return -ENOMEM; 203 } 204 205 return 0; 206} 207 208static int mqueue_get_sb(struct file_system_type *fs_type, 209 int flags, const char *dev_name, 210 void *data, struct vfsmount *mnt) 211{ 212 return get_sb_single(fs_type, flags, data, mqueue_fill_super, mnt); 213} 214 215static void init_once(void *foo, kmem_cache_t * cachep, unsigned long flags) 216{ 217 struct mqueue_inode_info *p = (struct mqueue_inode_info *) foo; 218 219 if ((flags & (SLAB_CTOR_VERIFY | SLAB_CTOR_CONSTRUCTOR)) == 220 SLAB_CTOR_CONSTRUCTOR) 221 inode_init_once(&p->vfs_inode); 222} 223 224static 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, SLAB_KERNEL); 229 if (!ei) 230 return NULL; 231 return &ei->vfs_inode; 232} 233 234static void mqueue_destroy_inode(struct inode *inode) 235{ 236 kmem_cache_free(mqueue_inode_cachep, MQUEUE_I(inode)); 237} 238 239static 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 271static 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; 300out_lock: 301 spin_unlock(&mq_lock); 302 return error; 303} 304 305static 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 inode->i_nlink--; 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*/ 323static 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_dentry->d_inode); 327 char buffer[FILENT_SIZE]; 328 size_t slen; 329 loff_t o; 330 331 if (!count) 332 return 0; 333 334 spin_lock(&info->lock); 335 snprintf(buffer, sizeof(buffer), 336 "QSIZE:%-10lu NOTIFY:%-5d SIGNO:%-5d NOTIFY_PID:%-6d\n", 337 info->qsize, 338 info->notify_owner ? info->notify.sigev_notify : 0, 339 (info->notify_owner && 340 info->notify.sigev_notify == SIGEV_SIGNAL) ? 341 info->notify.sigev_signo : 0, 342 info->notify_owner); 343 spin_unlock(&info->lock); 344 buffer[sizeof(buffer)-1] = '\0'; 345 slen = strlen(buffer)+1; 346 347 o = *off; 348 if (o > slen) 349 return 0; 350 351 if (o + count > slen) 352 count = slen - o; 353 354 if (copy_to_user(u_data, buffer + o, count)) 355 return -EFAULT; 356 357 *off = o + count; 358 filp->f_dentry->d_inode->i_atime = filp->f_dentry->d_inode->i_ctime = CURRENT_TIME; 359 return count; 360} 361 362static int mqueue_flush_file(struct file *filp, fl_owner_t id) 363{ 364 struct mqueue_inode_info *info = MQUEUE_I(filp->f_dentry->d_inode); 365 366 spin_lock(&info->lock); 367 if (current->tgid == info->notify_owner) 368 remove_notification(info); 369 370 spin_unlock(&info->lock); 371 return 0; 372} 373 374static unsigned int mqueue_poll_file(struct file *filp, struct poll_table_struct *poll_tab) 375{ 376 struct mqueue_inode_info *info = MQUEUE_I(filp->f_dentry->d_inode); 377 int retval = 0; 378 379 poll_wait(filp, &info->wait_q, poll_tab); 380 381 spin_lock(&info->lock); 382 if (info->attr.mq_curmsgs) 383 retval = POLLIN | POLLRDNORM; 384 385 if (info->attr.mq_curmsgs < info->attr.mq_maxmsg) 386 retval |= POLLOUT | POLLWRNORM; 387 spin_unlock(&info->lock); 388 389 return retval; 390} 391 392/* Adds current to info->e_wait_q[sr] before element with smaller prio */ 393static void wq_add(struct mqueue_inode_info *info, int sr, 394 struct ext_wait_queue *ewp) 395{ 396 struct ext_wait_queue *walk; 397 398 ewp->task = current; 399 400 list_for_each_entry(walk, &info->e_wait_q[sr].list, list) { 401 if (walk->task->static_prio <= current->static_prio) { 402 list_add_tail(&ewp->list, &walk->list); 403 return; 404 } 405 } 406 list_add_tail(&ewp->list, &info->e_wait_q[sr].list); 407} 408 409/* 410 * Puts current task to sleep. Caller must hold queue lock. After return 411 * lock isn't held. 412 * sr: SEND or RECV 413 */ 414static int wq_sleep(struct mqueue_inode_info *info, int sr, 415 long timeout, struct ext_wait_queue *ewp) 416{ 417 int retval; 418 signed long time; 419 420 wq_add(info, sr, ewp); 421 422 for (;;) { 423 set_current_state(TASK_INTERRUPTIBLE); 424 425 spin_unlock(&info->lock); 426 time = schedule_timeout(timeout); 427 428 while (ewp->state == STATE_PENDING) 429 cpu_relax(); 430 431 if (ewp->state == STATE_READY) { 432 retval = 0; 433 goto out; 434 } 435 spin_lock(&info->lock); 436 if (ewp->state == STATE_READY) { 437 retval = 0; 438 goto out_unlock; 439 } 440 if (signal_pending(current)) { 441 retval = -ERESTARTSYS; 442 break; 443 } 444 if (time == 0) { 445 retval = -ETIMEDOUT; 446 break; 447 } 448 } 449 list_del(&ewp->list); 450out_unlock: 451 spin_unlock(&info->lock); 452out: 453 return retval; 454} 455 456/* 457 * Returns waiting task that should be serviced first or NULL if none exists 458 */ 459static struct ext_wait_queue *wq_get_first_waiter( 460 struct mqueue_inode_info *info, int sr) 461{ 462 struct list_head *ptr; 463 464 ptr = info->e_wait_q[sr].list.prev; 465 if (ptr == &info->e_wait_q[sr].list) 466 return NULL; 467 return list_entry(ptr, struct ext_wait_queue, list); 468} 469 470/* Auxiliary functions to manipulate messages' list */ 471static void msg_insert(struct msg_msg *ptr, struct mqueue_inode_info *info) 472{ 473 int k; 474 475 k = info->attr.mq_curmsgs - 1; 476 while (k >= 0 && info->messages[k]->m_type >= ptr->m_type) { 477 info->messages[k + 1] = info->messages[k]; 478 k--; 479 } 480 info->attr.mq_curmsgs++; 481 info->qsize += ptr->m_ts; 482 info->messages[k + 1] = ptr; 483} 484 485static inline struct msg_msg *msg_get(struct mqueue_inode_info *info) 486{ 487 info->qsize -= info->messages[--info->attr.mq_curmsgs]->m_ts; 488 return info->messages[info->attr.mq_curmsgs]; 489} 490 491static inline void set_cookie(struct sk_buff *skb, char code) 492{ 493 ((char*)skb->data)[NOTIFY_COOKIE_LEN-1] = code; 494} 495 496/* 497 * The next function is only to split too long sys_mq_timedsend 498 */ 499static void __do_notify(struct mqueue_inode_info *info) 500{ 501 /* notification 502 * invoked when there is registered process and there isn't process 503 * waiting synchronously for message AND state of queue changed from 504 * empty to not empty. Here we are sure that no one is waiting 505 * synchronously. */ 506 if (info->notify_owner && 507 info->attr.mq_curmsgs == 1) { 508 struct siginfo sig_i; 509 switch (info->notify.sigev_notify) { 510 case SIGEV_NONE: 511 break; 512 case SIGEV_SIGNAL: 513 /* sends signal */ 514 515 sig_i.si_signo = info->notify.sigev_signo; 516 sig_i.si_errno = 0; 517 sig_i.si_code = SI_MESGQ; 518 sig_i.si_value = info->notify.sigev_value; 519 sig_i.si_pid = current->tgid; 520 sig_i.si_uid = current->uid; 521 522 kill_proc_info(info->notify.sigev_signo, 523 &sig_i, info->notify_owner); 524 break; 525 case SIGEV_THREAD: 526 set_cookie(info->notify_cookie, NOTIFY_WOKENUP); 527 netlink_sendskb(info->notify_sock, 528 info->notify_cookie, 0); 529 break; 530 } 531 /* after notification unregisters process */ 532 info->notify_owner = 0; 533 } 534 wake_up(&info->wait_q); 535} 536 537static long prepare_timeout(const struct timespec __user *u_arg) 538{ 539 struct timespec ts, nowts; 540 long timeout; 541 542 if (u_arg) { 543 if (unlikely(copy_from_user(&ts, u_arg, 544 sizeof(struct timespec)))) 545 return -EFAULT; 546 547 if (unlikely(ts.tv_nsec < 0 || ts.tv_sec < 0 548 || ts.tv_nsec >= NSEC_PER_SEC)) 549 return -EINVAL; 550 nowts = CURRENT_TIME; 551 /* first subtract as jiffies can't be too big */ 552 ts.tv_sec -= nowts.tv_sec; 553 if (ts.tv_nsec < nowts.tv_nsec) { 554 ts.tv_nsec += NSEC_PER_SEC; 555 ts.tv_sec--; 556 } 557 ts.tv_nsec -= nowts.tv_nsec; 558 if (ts.tv_sec < 0) 559 return 0; 560 561 timeout = timespec_to_jiffies(&ts) + 1; 562 } else 563 return MAX_SCHEDULE_TIMEOUT; 564 565 return timeout; 566} 567 568static void remove_notification(struct mqueue_inode_info *info) 569{ 570 if (info->notify_owner != 0 && 571 info->notify.sigev_notify == SIGEV_THREAD) { 572 set_cookie(info->notify_cookie, NOTIFY_REMOVED); 573 netlink_sendskb(info->notify_sock, info->notify_cookie, 0); 574 } 575 info->notify_owner = 0; 576} 577 578static int mq_attr_ok(struct mq_attr *attr) 579{ 580 if (attr->mq_maxmsg <= 0 || attr->mq_msgsize <= 0) 581 return 0; 582 if (capable(CAP_SYS_RESOURCE)) { 583 if (attr->mq_maxmsg > HARD_MSGMAX) 584 return 0; 585 } else { 586 if (attr->mq_maxmsg > msg_max || 587 attr->mq_msgsize > msgsize_max) 588 return 0; 589 } 590 /* check for overflow */ 591 if (attr->mq_msgsize > ULONG_MAX/attr->mq_maxmsg) 592 return 0; 593 if ((unsigned long)(attr->mq_maxmsg * attr->mq_msgsize) + 594 (attr->mq_maxmsg * sizeof (struct msg_msg *)) < 595 (unsigned long)(attr->mq_maxmsg * attr->mq_msgsize)) 596 return 0; 597 return 1; 598} 599 600/* 601 * Invoked when creating a new queue via sys_mq_open 602 */ 603static struct file *do_create(struct dentry *dir, struct dentry *dentry, 604 int oflag, mode_t mode, struct mq_attr __user *u_attr) 605{ 606 struct mq_attr attr; 607 int ret; 608 609 if (u_attr) { 610 ret = -EFAULT; 611 if (copy_from_user(&attr, u_attr, sizeof(attr))) 612 goto out; 613 ret = -EINVAL; 614 if (!mq_attr_ok(&attr)) 615 goto out; 616 /* store for use during create */ 617 dentry->d_fsdata = &attr; 618 } 619 620 mode &= ~current->fs->umask; 621 ret = vfs_create(dir->d_inode, dentry, mode, NULL); 622 dentry->d_fsdata = NULL; 623 if (ret) 624 goto out; 625 626 return dentry_open(dentry, mqueue_mnt, oflag); 627 628out: 629 dput(dentry); 630 mntput(mqueue_mnt); 631 return ERR_PTR(ret); 632} 633 634/* Opens existing queue */ 635static struct file *do_open(struct dentry *dentry, int oflag) 636{ 637static int oflag2acc[O_ACCMODE] = { MAY_READ, MAY_WRITE, 638 MAY_READ | MAY_WRITE }; 639 640 if ((oflag & O_ACCMODE) == (O_RDWR | O_WRONLY)) { 641 dput(dentry); 642 mntput(mqueue_mnt); 643 return ERR_PTR(-EINVAL); 644 } 645 646 if (permission(dentry->d_inode, oflag2acc[oflag & O_ACCMODE], NULL)) { 647 dput(dentry); 648 mntput(mqueue_mnt); 649 return ERR_PTR(-EACCES); 650 } 651 652 return dentry_open(dentry, mqueue_mnt, oflag); 653} 654 655asmlinkage long sys_mq_open(const char __user *u_name, int oflag, mode_t mode, 656 struct mq_attr __user *u_attr) 657{ 658 struct dentry *dentry; 659 struct file *filp; 660 char *name; 661 int fd, error; 662 663 error = audit_mq_open(oflag, mode, u_attr); 664 if (error != 0) 665 return error; 666 667 if (IS_ERR(name = getname(u_name))) 668 return PTR_ERR(name); 669 670 fd = get_unused_fd(); 671 if (fd < 0) 672 goto out_putname; 673 674 mutex_lock(&mqueue_mnt->mnt_root->d_inode->i_mutex); 675 dentry = lookup_one_len(name, mqueue_mnt->mnt_root, strlen(name)); 676 if (IS_ERR(dentry)) { 677 error = PTR_ERR(dentry); 678 goto out_err; 679 } 680 mntget(mqueue_mnt); 681 682 if (oflag & O_CREAT) { 683 if (dentry->d_inode) { /* entry already exists */ 684 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, u_attr); 691 } 692 } else { 693 error = -ENOENT; 694 if (!dentry->d_inode) 695 goto out; 696 filp = do_open(dentry, oflag); 697 } 698 699 if (IS_ERR(filp)) { 700 error = PTR_ERR(filp); 701 goto out_putfd; 702 } 703 704 set_close_on_exec(fd, 1); 705 fd_install(fd, filp); 706 goto out_upsem; 707 708out: 709 dput(dentry); 710 mntput(mqueue_mnt); 711out_putfd: 712 put_unused_fd(fd); 713out_err: 714 fd = error; 715out_upsem: 716 mutex_unlock(&mqueue_mnt->mnt_root->d_inode->i_mutex); 717out_putname: 718 putname(name); 719 return fd; 720} 721 722asmlinkage long sys_mq_unlink(const char __user *u_name) 723{ 724 int err; 725 char *name; 726 struct dentry *dentry; 727 struct inode *inode = NULL; 728 729 name = getname(u_name); 730 if (IS_ERR(name)) 731 return PTR_ERR(name); 732 733 mutex_lock(&mqueue_mnt->mnt_root->d_inode->i_mutex); 734 dentry = lookup_one_len(name, mqueue_mnt->mnt_root, strlen(name)); 735 if (IS_ERR(dentry)) { 736 err = PTR_ERR(dentry); 737 goto out_unlock; 738 } 739 740 if (!dentry->d_inode) { 741 err = -ENOENT; 742 goto out_err; 743 } 744 745 inode = dentry->d_inode; 746 if (inode) 747 atomic_inc(&inode->i_count); 748 749 err = vfs_unlink(dentry->d_parent->d_inode, dentry); 750out_err: 751 dput(dentry); 752 753out_unlock: 754 mutex_unlock(&mqueue_mnt->mnt_root->d_inode->i_mutex); 755 putname(name); 756 if (inode) 757 iput(inode); 758 759 return err; 760} 761 762/* Pipelined send and receive functions. 763 * 764 * If a receiver finds no waiting message, then it registers itself in the 765 * list of waiting receivers. A sender checks that list before adding the new 766 * message into the message array. If there is a waiting receiver, then it 767 * bypasses the message array and directly hands the message over to the 768 * receiver. 769 * The receiver accepts the message and returns without grabbing the queue 770 * spinlock. Therefore an intermediate STATE_PENDING state and memory barriers 771 * are necessary. The same algorithm is used for sysv semaphores, see 772 * ipc/sem.c for more details. 773 * 774 * The same algorithm is used for senders. 775 */ 776 777/* pipelined_send() - send a message directly to the task waiting in 778 * sys_mq_timedreceive() (without inserting message into a queue). 779 */ 780static inline void pipelined_send(struct mqueue_inode_info *info, 781 struct msg_msg *message, 782 struct ext_wait_queue *receiver) 783{ 784 receiver->msg = message; 785 list_del(&receiver->list); 786 receiver->state = STATE_PENDING; 787 wake_up_process(receiver->task); 788 smp_wmb(); 789 receiver->state = STATE_READY; 790} 791 792/* pipelined_receive() - if there is task waiting in sys_mq_timedsend() 793 * gets its message and put to the queue (we have one free place for sure). */ 794static inline void pipelined_receive(struct mqueue_inode_info *info) 795{ 796 struct ext_wait_queue *sender = wq_get_first_waiter(info, SEND); 797 798 if (!sender) { 799 /* for poll */ 800 wake_up_interruptible(&info->wait_q); 801 return; 802 } 803 msg_insert(sender->msg, info); 804 list_del(&sender->list); 805 sender->state = STATE_PENDING; 806 wake_up_process(sender->task); 807 smp_wmb(); 808 sender->state = STATE_READY; 809} 810 811asmlinkage long sys_mq_timedsend(mqd_t mqdes, const char __user *u_msg_ptr, 812 size_t msg_len, unsigned int msg_prio, 813 const struct timespec __user *u_abs_timeout) 814{ 815 struct file *filp; 816 struct inode *inode; 817 struct ext_wait_queue wait; 818 struct ext_wait_queue *receiver; 819 struct msg_msg *msg_ptr; 820 struct mqueue_inode_info *info; 821 long timeout; 822 int ret; 823 824 ret = audit_mq_timedsend(mqdes, msg_len, msg_prio, u_abs_timeout); 825 if (ret != 0) 826 return ret; 827 828 if (unlikely(msg_prio >= (unsigned long) MQ_PRIO_MAX)) 829 return -EINVAL; 830 831 timeout = prepare_timeout(u_abs_timeout); 832 833 ret = -EBADF; 834 filp = fget(mqdes); 835 if (unlikely(!filp)) 836 goto out; 837 838 inode = filp->f_dentry->d_inode; 839 if (unlikely(filp->f_op != &mqueue_file_operations)) 840 goto out_fput; 841 info = MQUEUE_I(inode); 842 843 if (unlikely(!(filp->f_mode & FMODE_WRITE))) 844 goto out_fput; 845 846 if (unlikely(msg_len > info->attr.mq_msgsize)) { 847 ret = -EMSGSIZE; 848 goto out_fput; 849 } 850 851 /* First try to allocate memory, before doing anything with 852 * existing queues. */ 853 msg_ptr = load_msg(u_msg_ptr, msg_len); 854 if (IS_ERR(msg_ptr)) { 855 ret = PTR_ERR(msg_ptr); 856 goto out_fput; 857 } 858 msg_ptr->m_ts = msg_len; 859 msg_ptr->m_type = msg_prio; 860 861 spin_lock(&info->lock); 862 863 if (info->attr.mq_curmsgs == info->attr.mq_maxmsg) { 864 if (filp->f_flags & O_NONBLOCK) { 865 spin_unlock(&info->lock); 866 ret = -EAGAIN; 867 } else if (unlikely(timeout < 0)) { 868 spin_unlock(&info->lock); 869 ret = timeout; 870 } else { 871 wait.task = current; 872 wait.msg = (void *) msg_ptr; 873 wait.state = STATE_NONE; 874 ret = wq_sleep(info, SEND, timeout, &wait); 875 } 876 if (ret < 0) 877 free_msg(msg_ptr); 878 } else { 879 receiver = wq_get_first_waiter(info, RECV); 880 if (receiver) { 881 pipelined_send(info, msg_ptr, receiver); 882 } else { 883 /* adds message to the queue */ 884 msg_insert(msg_ptr, info); 885 __do_notify(info); 886 } 887 inode->i_atime = inode->i_mtime = inode->i_ctime = 888 CURRENT_TIME; 889 spin_unlock(&info->lock); 890 ret = 0; 891 } 892out_fput: 893 fput(filp); 894out: 895 return ret; 896} 897 898asmlinkage ssize_t sys_mq_timedreceive(mqd_t mqdes, char __user *u_msg_ptr, 899 size_t msg_len, unsigned int __user *u_msg_prio, 900 const struct timespec __user *u_abs_timeout) 901{ 902 long timeout; 903 ssize_t ret; 904 struct msg_msg *msg_ptr; 905 struct file *filp; 906 struct inode *inode; 907 struct mqueue_inode_info *info; 908 struct ext_wait_queue wait; 909 910 ret = audit_mq_timedreceive(mqdes, msg_len, u_msg_prio, u_abs_timeout); 911 if (ret != 0) 912 return ret; 913 914 timeout = prepare_timeout(u_abs_timeout); 915 916 ret = -EBADF; 917 filp = fget(mqdes); 918 if (unlikely(!filp)) 919 goto out; 920 921 inode = filp->f_dentry->d_inode; 922 if (unlikely(filp->f_op != &mqueue_file_operations)) 923 goto out_fput; 924 info = MQUEUE_I(inode); 925 926 if (unlikely(!(filp->f_mode & FMODE_READ))) 927 goto out_fput; 928 929 /* checks if buffer is big enough */ 930 if (unlikely(msg_len < info->attr.mq_msgsize)) { 931 ret = -EMSGSIZE; 932 goto out_fput; 933 } 934 935 spin_lock(&info->lock); 936 if (info->attr.mq_curmsgs == 0) { 937 if (filp->f_flags & O_NONBLOCK) { 938 spin_unlock(&info->lock); 939 ret = -EAGAIN; 940 msg_ptr = NULL; 941 } else if (unlikely(timeout < 0)) { 942 spin_unlock(&info->lock); 943 ret = timeout; 944 msg_ptr = NULL; 945 } else { 946 wait.task = current; 947 wait.state = STATE_NONE; 948 ret = wq_sleep(info, RECV, timeout, &wait); 949 msg_ptr = wait.msg; 950 } 951 } else { 952 msg_ptr = msg_get(info); 953 954 inode->i_atime = inode->i_mtime = inode->i_ctime = 955 CURRENT_TIME; 956 957 /* There is now free space in queue. */ 958 pipelined_receive(info); 959 spin_unlock(&info->lock); 960 ret = 0; 961 } 962 if (ret == 0) { 963 ret = msg_ptr->m_ts; 964 965 if ((u_msg_prio && put_user(msg_ptr->m_type, u_msg_prio)) || 966 store_msg(u_msg_ptr, msg_ptr, msg_ptr->m_ts)) { 967 ret = -EFAULT; 968 } 969 free_msg(msg_ptr); 970 } 971out_fput: 972 fput(filp); 973out: 974 return ret; 975} 976 977/* 978 * Notes: the case when user wants us to deregister (with NULL as pointer) 979 * and he isn't currently owner of notification, will be silently discarded. 980 * It isn't explicitly defined in the POSIX. 981 */ 982asmlinkage long sys_mq_notify(mqd_t mqdes, 983 const struct sigevent __user *u_notification) 984{ 985 int ret; 986 struct file *filp; 987 struct sock *sock; 988 struct inode *inode; 989 struct sigevent notification; 990 struct mqueue_inode_info *info; 991 struct sk_buff *nc; 992 993 ret = audit_mq_notify(mqdes, u_notification); 994 if (ret != 0) 995 return ret; 996 997 nc = NULL; 998 sock = NULL; 999 if (u_notification != NULL) { 1000 if (copy_from_user(¬ification, u_notification, 1001 sizeof(struct sigevent))) 1002 return -EFAULT; 1003 1004 if (unlikely(notification.sigev_notify != SIGEV_NONE && 1005 notification.sigev_notify != SIGEV_SIGNAL && 1006 notification.sigev_notify != SIGEV_THREAD)) 1007 return -EINVAL; 1008 if (notification.sigev_notify == SIGEV_SIGNAL && 1009 !valid_signal(notification.sigev_signo)) { 1010 return -EINVAL; 1011 } 1012 if (notification.sigev_notify == SIGEV_THREAD) { 1013 /* create the notify skb */ 1014 nc = alloc_skb(NOTIFY_COOKIE_LEN, GFP_KERNEL); 1015 ret = -ENOMEM; 1016 if (!nc) 1017 goto out; 1018 ret = -EFAULT; 1019 if (copy_from_user(nc->data, 1020 notification.sigev_value.sival_ptr, 1021 NOTIFY_COOKIE_LEN)) { 1022 goto out; 1023 } 1024 1025 /* TODO: add a header? */ 1026 skb_put(nc, NOTIFY_COOKIE_LEN); 1027 /* and attach it to the socket */ 1028retry: 1029 filp = fget(notification.sigev_signo); 1030 ret = -EBADF; 1031 if (!filp) 1032 goto out; 1033 sock = netlink_getsockbyfilp(filp); 1034 fput(filp); 1035 if (IS_ERR(sock)) { 1036 ret = PTR_ERR(sock); 1037 sock = NULL; 1038 goto out; 1039 } 1040 1041 ret = netlink_attachskb(sock, nc, 0, 1042 MAX_SCHEDULE_TIMEOUT, NULL); 1043 if (ret == 1) 1044 goto retry; 1045 if (ret) { 1046 sock = NULL; 1047 nc = NULL; 1048 goto out; 1049 } 1050 } 1051 } 1052 1053 ret = -EBADF; 1054 filp = fget(mqdes); 1055 if (!filp) 1056 goto out; 1057 1058 inode = filp->f_dentry->d_inode; 1059 if (unlikely(filp->f_op != &mqueue_file_operations)) 1060 goto out_fput; 1061 info = MQUEUE_I(inode); 1062 1063 ret = 0; 1064 spin_lock(&info->lock); 1065 if (u_notification == NULL) { 1066 if (info->notify_owner == current->tgid) { 1067 remove_notification(info); 1068 inode->i_atime = inode->i_ctime = CURRENT_TIME; 1069 } 1070 } else if (info->notify_owner != 0) { 1071 ret = -EBUSY; 1072 } else { 1073 switch (notification.sigev_notify) { 1074 case SIGEV_NONE: 1075 info->notify.sigev_notify = SIGEV_NONE; 1076 break; 1077 case SIGEV_THREAD: 1078 info->notify_sock = sock; 1079 info->notify_cookie = nc; 1080 sock = NULL; 1081 nc = NULL; 1082 info->notify.sigev_notify = SIGEV_THREAD; 1083 break; 1084 case SIGEV_SIGNAL: 1085 info->notify.sigev_signo = notification.sigev_signo; 1086 info->notify.sigev_value = notification.sigev_value; 1087 info->notify.sigev_notify = SIGEV_SIGNAL; 1088 break; 1089 } 1090 info->notify_owner = current->tgid; 1091 inode->i_atime = inode->i_ctime = CURRENT_TIME; 1092 } 1093 spin_unlock(&info->lock); 1094out_fput: 1095 fput(filp); 1096out: 1097 if (sock) { 1098 netlink_detachskb(sock, nc); 1099 } else if (nc) { 1100 dev_kfree_skb(nc); 1101 } 1102 return ret; 1103} 1104 1105asmlinkage long sys_mq_getsetattr(mqd_t mqdes, 1106 const struct mq_attr __user *u_mqstat, 1107 struct mq_attr __user *u_omqstat) 1108{ 1109 int ret; 1110 struct mq_attr mqstat, omqstat; 1111 struct file *filp; 1112 struct inode *inode; 1113 struct mqueue_inode_info *info; 1114 1115 if (u_mqstat != NULL) { 1116 if (copy_from_user(&mqstat, u_mqstat, sizeof(struct mq_attr))) 1117 return -EFAULT; 1118 if (mqstat.mq_flags & (~O_NONBLOCK)) 1119 return -EINVAL; 1120 } 1121 1122 ret = -EBADF; 1123 filp = fget(mqdes); 1124 if (!filp) 1125 goto out; 1126 1127 inode = filp->f_dentry->d_inode; 1128 if (unlikely(filp->f_op != &mqueue_file_operations)) 1129 goto out_fput; 1130 info = MQUEUE_I(inode); 1131 1132 spin_lock(&info->lock); 1133 1134 omqstat = info->attr; 1135 omqstat.mq_flags = filp->f_flags & O_NONBLOCK; 1136 if (u_mqstat) { 1137 ret = audit_mq_getsetattr(mqdes, &mqstat); 1138 if (ret != 0) 1139 goto out; 1140 if (mqstat.mq_flags & O_NONBLOCK) 1141 filp->f_flags |= O_NONBLOCK; 1142 else 1143 filp->f_flags &= ~O_NONBLOCK; 1144 1145 inode->i_atime = inode->i_ctime = CURRENT_TIME; 1146 } 1147 1148 spin_unlock(&info->lock); 1149 1150 ret = 0; 1151 if (u_omqstat != NULL && copy_to_user(u_omqstat, &omqstat, 1152 sizeof(struct mq_attr))) 1153 ret = -EFAULT; 1154 1155out_fput: 1156 fput(filp); 1157out: 1158 return ret; 1159} 1160 1161static struct inode_operations mqueue_dir_inode_operations = { 1162 .lookup = simple_lookup, 1163 .create = mqueue_create, 1164 .unlink = mqueue_unlink, 1165}; 1166 1167static struct file_operations mqueue_file_operations = { 1168 .flush = mqueue_flush_file, 1169 .poll = mqueue_poll_file, 1170 .read = mqueue_read_file, 1171}; 1172 1173static struct super_operations mqueue_super_ops = { 1174 .alloc_inode = mqueue_alloc_inode, 1175 .destroy_inode = mqueue_destroy_inode, 1176 .statfs = simple_statfs, 1177 .delete_inode = mqueue_delete_inode, 1178 .drop_inode = generic_delete_inode, 1179}; 1180 1181static struct file_system_type mqueue_fs_type = { 1182 .name = "mqueue", 1183 .get_sb = mqueue_get_sb, 1184 .kill_sb = kill_litter_super, 1185}; 1186 1187static int msg_max_limit_min = DFLT_MSGMAX; 1188static int msg_max_limit_max = HARD_MSGMAX; 1189 1190static int msg_maxsize_limit_min = DFLT_MSGSIZEMAX; 1191static int msg_maxsize_limit_max = INT_MAX; 1192 1193static ctl_table mq_sysctls[] = { 1194 { 1195 .ctl_name = CTL_QUEUESMAX, 1196 .procname = "queues_max", 1197 .data = &queues_max, 1198 .maxlen = sizeof(int), 1199 .mode = 0644, 1200 .proc_handler = &proc_dointvec, 1201 }, 1202 { 1203 .ctl_name = CTL_MSGMAX, 1204 .procname = "msg_max", 1205 .data = &msg_max, 1206 .maxlen = sizeof(int), 1207 .mode = 0644, 1208 .proc_handler = &proc_dointvec_minmax, 1209 .extra1 = &msg_max_limit_min, 1210 .extra2 = &msg_max_limit_max, 1211 }, 1212 { 1213 .ctl_name = CTL_MSGSIZEMAX, 1214 .procname = "msgsize_max", 1215 .data = &msgsize_max, 1216 .maxlen = sizeof(int), 1217 .mode = 0644, 1218 .proc_handler = &proc_dointvec_minmax, 1219 .extra1 = &msg_maxsize_limit_min, 1220 .extra2 = &msg_maxsize_limit_max, 1221 }, 1222 { .ctl_name = 0 } 1223}; 1224 1225static ctl_table mq_sysctl_dir[] = { 1226 { 1227 .ctl_name = FS_MQUEUE, 1228 .procname = "mqueue", 1229 .mode = 0555, 1230 .child = mq_sysctls, 1231 }, 1232 { .ctl_name = 0 } 1233}; 1234 1235static ctl_table mq_sysctl_root[] = { 1236 { 1237 .ctl_name = CTL_FS, 1238 .procname = "fs", 1239 .mode = 0555, 1240 .child = mq_sysctl_dir, 1241 }, 1242 { .ctl_name = 0 } 1243}; 1244 1245static int __init init_mqueue_fs(void) 1246{ 1247 int error; 1248 1249 mqueue_inode_cachep = kmem_cache_create("mqueue_inode_cache", 1250 sizeof(struct mqueue_inode_info), 0, 1251 SLAB_HWCACHE_ALIGN, init_once, NULL); 1252 if (mqueue_inode_cachep == NULL) 1253 return -ENOMEM; 1254 1255 /* ignore failues - they are not fatal */ 1256 mq_sysctl_table = register_sysctl_table(mq_sysctl_root, 0); 1257 1258 error = register_filesystem(&mqueue_fs_type); 1259 if (error) 1260 goto out_sysctl; 1261 1262 if (IS_ERR(mqueue_mnt = kern_mount(&mqueue_fs_type))) { 1263 error = PTR_ERR(mqueue_mnt); 1264 goto out_filesystem; 1265 } 1266 1267 /* internal initialization - not common for vfs */ 1268 queues_count = 0; 1269 spin_lock_init(&mq_lock); 1270 1271 return 0; 1272 1273out_filesystem: 1274 unregister_filesystem(&mqueue_fs_type); 1275out_sysctl: 1276 if (mq_sysctl_table) 1277 unregister_sysctl_table(mq_sysctl_table); 1278 if (kmem_cache_destroy(mqueue_inode_cachep)) { 1279 printk(KERN_INFO 1280 "mqueue_inode_cache: not all structures were freed\n"); 1281 } 1282 return error; 1283} 1284 1285__initcall(init_mqueue_fs); 1286