mqueue.c revision 1b1dcc1b57a49136f118a0f16367256ff9994a69
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 * This file is released under the GPL. 12 */ 13 14#include <linux/init.h> 15#include <linux/pagemap.h> 16#include <linux/file.h> 17#include <linux/mount.h> 18#include <linux/namei.h> 19#include <linux/sysctl.h> 20#include <linux/poll.h> 21#include <linux/mqueue.h> 22#include <linux/msg.h> 23#include <linux/skbuff.h> 24#include <linux/netlink.h> 25#include <linux/syscalls.h> 26#include <linux/signal.h> 27#include <net/sock.h> 28#include "util.h" 29 30#define MQUEUE_MAGIC 0x19800202 31#define DIRENT_SIZE 20 32#define FILENT_SIZE 80 33 34#define SEND 0 35#define RECV 1 36 37#define STATE_NONE 0 38#define STATE_PENDING 1 39#define STATE_READY 2 40 41/* used by sysctl */ 42#define FS_MQUEUE 1 43#define CTL_QUEUESMAX 2 44#define CTL_MSGMAX 3 45#define CTL_MSGSIZEMAX 4 46 47/* default values */ 48#define DFLT_QUEUESMAX 256 /* max number of message queues */ 49#define DFLT_MSGMAX 10 /* max number of messages in each queue */ 50#define HARD_MSGMAX (131072/sizeof(void*)) 51#define DFLT_MSGSIZEMAX 8192 /* max message size */ 52 53#define NOTIFY_COOKIE_LEN 32 54 55struct ext_wait_queue { /* queue of sleeping tasks */ 56 struct task_struct *task; 57 struct list_head list; 58 struct msg_msg *msg; /* ptr of loaded message */ 59 int state; /* one of STATE_* values */ 60}; 61 62struct mqueue_inode_info { 63 spinlock_t lock; 64 struct inode vfs_inode; 65 wait_queue_head_t wait_q; 66 67 struct msg_msg **messages; 68 struct mq_attr attr; 69 70 struct sigevent notify; 71 pid_t notify_owner; 72 struct user_struct *user; /* user who created, for accounting */ 73 struct sock *notify_sock; 74 struct sk_buff *notify_cookie; 75 76 /* for tasks waiting for free space and messages, respectively */ 77 struct ext_wait_queue e_wait_q[2]; 78 79 unsigned long qsize; /* size of queue in memory (sum of all msgs) */ 80}; 81 82static struct inode_operations mqueue_dir_inode_operations; 83static struct file_operations mqueue_file_operations; 84static struct super_operations mqueue_super_ops; 85static void remove_notification(struct mqueue_inode_info *info); 86 87static spinlock_t mq_lock; 88static kmem_cache_t *mqueue_inode_cachep; 89static struct vfsmount *mqueue_mnt; 90 91static unsigned int queues_count; 92static unsigned int queues_max = DFLT_QUEUESMAX; 93static unsigned int msg_max = DFLT_MSGMAX; 94static unsigned int msgsize_max = DFLT_MSGSIZEMAX; 95 96static struct ctl_table_header * mq_sysctl_table; 97 98static inline struct mqueue_inode_info *MQUEUE_I(struct inode *inode) 99{ 100 return container_of(inode, struct mqueue_inode_info, vfs_inode); 101} 102 103static struct inode *mqueue_get_inode(struct super_block *sb, int mode, 104 struct mq_attr *attr) 105{ 106 struct inode *inode; 107 108 inode = new_inode(sb); 109 if (inode) { 110 inode->i_mode = mode; 111 inode->i_uid = current->fsuid; 112 inode->i_gid = current->fsgid; 113 inode->i_blksize = PAGE_CACHE_SIZE; 114 inode->i_blocks = 0; 115 inode->i_mtime = inode->i_ctime = inode->i_atime = 116 CURRENT_TIME; 117 118 if (S_ISREG(mode)) { 119 struct mqueue_inode_info *info; 120 struct task_struct *p = current; 121 struct user_struct *u = p->user; 122 unsigned long mq_bytes, mq_msg_tblsz; 123 124 inode->i_fop = &mqueue_file_operations; 125 inode->i_size = FILENT_SIZE; 126 /* mqueue specific info */ 127 info = MQUEUE_I(inode); 128 spin_lock_init(&info->lock); 129 init_waitqueue_head(&info->wait_q); 130 INIT_LIST_HEAD(&info->e_wait_q[0].list); 131 INIT_LIST_HEAD(&info->e_wait_q[1].list); 132 info->messages = NULL; 133 info->notify_owner = 0; 134 info->qsize = 0; 135 info->user = NULL; /* set when all is ok */ 136 memset(&info->attr, 0, sizeof(info->attr)); 137 info->attr.mq_maxmsg = DFLT_MSGMAX; 138 info->attr.mq_msgsize = DFLT_MSGSIZEMAX; 139 if (attr) { 140 info->attr.mq_maxmsg = attr->mq_maxmsg; 141 info->attr.mq_msgsize = attr->mq_msgsize; 142 } 143 mq_msg_tblsz = info->attr.mq_maxmsg * sizeof(struct msg_msg *); 144 mq_bytes = (mq_msg_tblsz + 145 (info->attr.mq_maxmsg * info->attr.mq_msgsize)); 146 147 spin_lock(&mq_lock); 148 if (u->mq_bytes + mq_bytes < u->mq_bytes || 149 u->mq_bytes + mq_bytes > 150 p->signal->rlim[RLIMIT_MSGQUEUE].rlim_cur) { 151 spin_unlock(&mq_lock); 152 goto out_inode; 153 } 154 u->mq_bytes += mq_bytes; 155 spin_unlock(&mq_lock); 156 157 info->messages = kmalloc(mq_msg_tblsz, GFP_KERNEL); 158 if (!info->messages) { 159 spin_lock(&mq_lock); 160 u->mq_bytes -= mq_bytes; 161 spin_unlock(&mq_lock); 162 goto out_inode; 163 } 164 /* all is ok */ 165 info->user = get_uid(u); 166 } else if (S_ISDIR(mode)) { 167 inode->i_nlink++; 168 /* Some things misbehave if size == 0 on a directory */ 169 inode->i_size = 2 * DIRENT_SIZE; 170 inode->i_op = &mqueue_dir_inode_operations; 171 inode->i_fop = &simple_dir_operations; 172 } 173 } 174 return inode; 175out_inode: 176 make_bad_inode(inode); 177 iput(inode); 178 return NULL; 179} 180 181static int mqueue_fill_super(struct super_block *sb, void *data, int silent) 182{ 183 struct inode *inode; 184 185 sb->s_blocksize = PAGE_CACHE_SIZE; 186 sb->s_blocksize_bits = PAGE_CACHE_SHIFT; 187 sb->s_magic = MQUEUE_MAGIC; 188 sb->s_op = &mqueue_super_ops; 189 190 inode = mqueue_get_inode(sb, S_IFDIR | S_ISVTX | S_IRWXUGO, NULL); 191 if (!inode) 192 return -ENOMEM; 193 194 sb->s_root = d_alloc_root(inode); 195 if (!sb->s_root) { 196 iput(inode); 197 return -ENOMEM; 198 } 199 200 return 0; 201} 202 203static struct super_block *mqueue_get_sb(struct file_system_type *fs_type, 204 int flags, const char *dev_name, 205 void *data) 206{ 207 return get_sb_single(fs_type, flags, data, mqueue_fill_super); 208} 209 210static void init_once(void *foo, kmem_cache_t * cachep, unsigned long flags) 211{ 212 struct mqueue_inode_info *p = (struct mqueue_inode_info *) foo; 213 214 if ((flags & (SLAB_CTOR_VERIFY | SLAB_CTOR_CONSTRUCTOR)) == 215 SLAB_CTOR_CONSTRUCTOR) 216 inode_init_once(&p->vfs_inode); 217} 218 219static struct inode *mqueue_alloc_inode(struct super_block *sb) 220{ 221 struct mqueue_inode_info *ei; 222 223 ei = kmem_cache_alloc(mqueue_inode_cachep, SLAB_KERNEL); 224 if (!ei) 225 return NULL; 226 return &ei->vfs_inode; 227} 228 229static void mqueue_destroy_inode(struct inode *inode) 230{ 231 kmem_cache_free(mqueue_inode_cachep, MQUEUE_I(inode)); 232} 233 234static void mqueue_delete_inode(struct inode *inode) 235{ 236 struct mqueue_inode_info *info; 237 struct user_struct *user; 238 unsigned long mq_bytes; 239 int i; 240 241 if (S_ISDIR(inode->i_mode)) { 242 clear_inode(inode); 243 return; 244 } 245 info = MQUEUE_I(inode); 246 spin_lock(&info->lock); 247 for (i = 0; i < info->attr.mq_curmsgs; i++) 248 free_msg(info->messages[i]); 249 kfree(info->messages); 250 spin_unlock(&info->lock); 251 252 clear_inode(inode); 253 254 mq_bytes = (info->attr.mq_maxmsg * sizeof(struct msg_msg *) + 255 (info->attr.mq_maxmsg * info->attr.mq_msgsize)); 256 user = info->user; 257 if (user) { 258 spin_lock(&mq_lock); 259 user->mq_bytes -= mq_bytes; 260 queues_count--; 261 spin_unlock(&mq_lock); 262 free_uid(user); 263 } 264} 265 266static int mqueue_create(struct inode *dir, struct dentry *dentry, 267 int mode, struct nameidata *nd) 268{ 269 struct inode *inode; 270 struct mq_attr *attr = dentry->d_fsdata; 271 int error; 272 273 spin_lock(&mq_lock); 274 if (queues_count >= queues_max && !capable(CAP_SYS_RESOURCE)) { 275 error = -ENOSPC; 276 goto out_lock; 277 } 278 queues_count++; 279 spin_unlock(&mq_lock); 280 281 inode = mqueue_get_inode(dir->i_sb, mode, attr); 282 if (!inode) { 283 error = -ENOMEM; 284 spin_lock(&mq_lock); 285 queues_count--; 286 goto out_lock; 287 } 288 289 dir->i_size += DIRENT_SIZE; 290 dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME; 291 292 d_instantiate(dentry, inode); 293 dget(dentry); 294 return 0; 295out_lock: 296 spin_unlock(&mq_lock); 297 return error; 298} 299 300static int mqueue_unlink(struct inode *dir, struct dentry *dentry) 301{ 302 struct inode *inode = dentry->d_inode; 303 304 dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME; 305 dir->i_size -= DIRENT_SIZE; 306 inode->i_nlink--; 307 dput(dentry); 308 return 0; 309} 310 311/* 312* This is routine for system read from queue file. 313* To avoid mess with doing here some sort of mq_receive we allow 314* to read only queue size & notification info (the only values 315* that are interesting from user point of view and aren't accessible 316* through std routines) 317*/ 318static ssize_t mqueue_read_file(struct file *filp, char __user *u_data, 319 size_t count, loff_t * off) 320{ 321 struct mqueue_inode_info *info = MQUEUE_I(filp->f_dentry->d_inode); 322 char buffer[FILENT_SIZE]; 323 size_t slen; 324 loff_t o; 325 326 if (!count) 327 return 0; 328 329 spin_lock(&info->lock); 330 snprintf(buffer, sizeof(buffer), 331 "QSIZE:%-10lu NOTIFY:%-5d SIGNO:%-5d NOTIFY_PID:%-6d\n", 332 info->qsize, 333 info->notify_owner ? info->notify.sigev_notify : 0, 334 (info->notify_owner && 335 info->notify.sigev_notify == SIGEV_SIGNAL) ? 336 info->notify.sigev_signo : 0, 337 info->notify_owner); 338 spin_unlock(&info->lock); 339 buffer[sizeof(buffer)-1] = '\0'; 340 slen = strlen(buffer)+1; 341 342 o = *off; 343 if (o > slen) 344 return 0; 345 346 if (o + count > slen) 347 count = slen - o; 348 349 if (copy_to_user(u_data, buffer + o, count)) 350 return -EFAULT; 351 352 *off = o + count; 353 filp->f_dentry->d_inode->i_atime = filp->f_dentry->d_inode->i_ctime = CURRENT_TIME; 354 return count; 355} 356 357static int mqueue_flush_file(struct file *filp) 358{ 359 struct mqueue_inode_info *info = MQUEUE_I(filp->f_dentry->d_inode); 360 361 spin_lock(&info->lock); 362 if (current->tgid == info->notify_owner) 363 remove_notification(info); 364 365 spin_unlock(&info->lock); 366 return 0; 367} 368 369static unsigned int mqueue_poll_file(struct file *filp, struct poll_table_struct *poll_tab) 370{ 371 struct mqueue_inode_info *info = MQUEUE_I(filp->f_dentry->d_inode); 372 int retval = 0; 373 374 poll_wait(filp, &info->wait_q, poll_tab); 375 376 spin_lock(&info->lock); 377 if (info->attr.mq_curmsgs) 378 retval = POLLIN | POLLRDNORM; 379 380 if (info->attr.mq_curmsgs < info->attr.mq_maxmsg) 381 retval |= POLLOUT | POLLWRNORM; 382 spin_unlock(&info->lock); 383 384 return retval; 385} 386 387/* Adds current to info->e_wait_q[sr] before element with smaller prio */ 388static void wq_add(struct mqueue_inode_info *info, int sr, 389 struct ext_wait_queue *ewp) 390{ 391 struct ext_wait_queue *walk; 392 393 ewp->task = current; 394 395 list_for_each_entry(walk, &info->e_wait_q[sr].list, list) { 396 if (walk->task->static_prio <= current->static_prio) { 397 list_add_tail(&ewp->list, &walk->list); 398 return; 399 } 400 } 401 list_add_tail(&ewp->list, &info->e_wait_q[sr].list); 402} 403 404/* 405 * Puts current task to sleep. Caller must hold queue lock. After return 406 * lock isn't held. 407 * sr: SEND or RECV 408 */ 409static int wq_sleep(struct mqueue_inode_info *info, int sr, 410 long timeout, struct ext_wait_queue *ewp) 411{ 412 int retval; 413 signed long time; 414 415 wq_add(info, sr, ewp); 416 417 for (;;) { 418 set_current_state(TASK_INTERRUPTIBLE); 419 420 spin_unlock(&info->lock); 421 time = schedule_timeout(timeout); 422 423 while (ewp->state == STATE_PENDING) 424 cpu_relax(); 425 426 if (ewp->state == STATE_READY) { 427 retval = 0; 428 goto out; 429 } 430 spin_lock(&info->lock); 431 if (ewp->state == STATE_READY) { 432 retval = 0; 433 goto out_unlock; 434 } 435 if (signal_pending(current)) { 436 retval = -ERESTARTSYS; 437 break; 438 } 439 if (time == 0) { 440 retval = -ETIMEDOUT; 441 break; 442 } 443 } 444 list_del(&ewp->list); 445out_unlock: 446 spin_unlock(&info->lock); 447out: 448 return retval; 449} 450 451/* 452 * Returns waiting task that should be serviced first or NULL if none exists 453 */ 454static struct ext_wait_queue *wq_get_first_waiter( 455 struct mqueue_inode_info *info, int sr) 456{ 457 struct list_head *ptr; 458 459 ptr = info->e_wait_q[sr].list.prev; 460 if (ptr == &info->e_wait_q[sr].list) 461 return NULL; 462 return list_entry(ptr, struct ext_wait_queue, list); 463} 464 465/* Auxiliary functions to manipulate messages' list */ 466static void msg_insert(struct msg_msg *ptr, struct mqueue_inode_info *info) 467{ 468 int k; 469 470 k = info->attr.mq_curmsgs - 1; 471 while (k >= 0 && info->messages[k]->m_type >= ptr->m_type) { 472 info->messages[k + 1] = info->messages[k]; 473 k--; 474 } 475 info->attr.mq_curmsgs++; 476 info->qsize += ptr->m_ts; 477 info->messages[k + 1] = ptr; 478} 479 480static inline struct msg_msg *msg_get(struct mqueue_inode_info *info) 481{ 482 info->qsize -= info->messages[--info->attr.mq_curmsgs]->m_ts; 483 return info->messages[info->attr.mq_curmsgs]; 484} 485 486static inline void set_cookie(struct sk_buff *skb, char code) 487{ 488 ((char*)skb->data)[NOTIFY_COOKIE_LEN-1] = code; 489} 490 491/* 492 * The next function is only to split too long sys_mq_timedsend 493 */ 494static void __do_notify(struct mqueue_inode_info *info) 495{ 496 /* notification 497 * invoked when there is registered process and there isn't process 498 * waiting synchronously for message AND state of queue changed from 499 * empty to not empty. Here we are sure that no one is waiting 500 * synchronously. */ 501 if (info->notify_owner && 502 info->attr.mq_curmsgs == 1) { 503 struct siginfo sig_i; 504 switch (info->notify.sigev_notify) { 505 case SIGEV_NONE: 506 break; 507 case SIGEV_SIGNAL: 508 /* sends signal */ 509 510 sig_i.si_signo = info->notify.sigev_signo; 511 sig_i.si_errno = 0; 512 sig_i.si_code = SI_MESGQ; 513 sig_i.si_value = info->notify.sigev_value; 514 sig_i.si_pid = current->tgid; 515 sig_i.si_uid = current->uid; 516 517 kill_proc_info(info->notify.sigev_signo, 518 &sig_i, info->notify_owner); 519 break; 520 case SIGEV_THREAD: 521 set_cookie(info->notify_cookie, NOTIFY_WOKENUP); 522 netlink_sendskb(info->notify_sock, 523 info->notify_cookie, 0); 524 break; 525 } 526 /* after notification unregisters process */ 527 info->notify_owner = 0; 528 } 529 wake_up(&info->wait_q); 530} 531 532static long prepare_timeout(const struct timespec __user *u_arg) 533{ 534 struct timespec ts, nowts; 535 long timeout; 536 537 if (u_arg) { 538 if (unlikely(copy_from_user(&ts, u_arg, 539 sizeof(struct timespec)))) 540 return -EFAULT; 541 542 if (unlikely(ts.tv_nsec < 0 || ts.tv_sec < 0 543 || ts.tv_nsec >= NSEC_PER_SEC)) 544 return -EINVAL; 545 nowts = CURRENT_TIME; 546 /* first subtract as jiffies can't be too big */ 547 ts.tv_sec -= nowts.tv_sec; 548 if (ts.tv_nsec < nowts.tv_nsec) { 549 ts.tv_nsec += NSEC_PER_SEC; 550 ts.tv_sec--; 551 } 552 ts.tv_nsec -= nowts.tv_nsec; 553 if (ts.tv_sec < 0) 554 return 0; 555 556 timeout = timespec_to_jiffies(&ts) + 1; 557 } else 558 return MAX_SCHEDULE_TIMEOUT; 559 560 return timeout; 561} 562 563static void remove_notification(struct mqueue_inode_info *info) 564{ 565 if (info->notify_owner != 0 && 566 info->notify.sigev_notify == SIGEV_THREAD) { 567 set_cookie(info->notify_cookie, NOTIFY_REMOVED); 568 netlink_sendskb(info->notify_sock, info->notify_cookie, 0); 569 } 570 info->notify_owner = 0; 571} 572 573static int mq_attr_ok(struct mq_attr *attr) 574{ 575 if (attr->mq_maxmsg <= 0 || attr->mq_msgsize <= 0) 576 return 0; 577 if (capable(CAP_SYS_RESOURCE)) { 578 if (attr->mq_maxmsg > HARD_MSGMAX) 579 return 0; 580 } else { 581 if (attr->mq_maxmsg > msg_max || 582 attr->mq_msgsize > msgsize_max) 583 return 0; 584 } 585 /* check for overflow */ 586 if (attr->mq_msgsize > ULONG_MAX/attr->mq_maxmsg) 587 return 0; 588 if ((unsigned long)(attr->mq_maxmsg * attr->mq_msgsize) + 589 (attr->mq_maxmsg * sizeof (struct msg_msg *)) < 590 (unsigned long)(attr->mq_maxmsg * attr->mq_msgsize)) 591 return 0; 592 return 1; 593} 594 595/* 596 * Invoked when creating a new queue via sys_mq_open 597 */ 598static struct file *do_create(struct dentry *dir, struct dentry *dentry, 599 int oflag, mode_t mode, struct mq_attr __user *u_attr) 600{ 601 struct file *filp; 602 struct mq_attr attr; 603 int ret; 604 605 if (u_attr != NULL) { 606 if (copy_from_user(&attr, u_attr, sizeof(attr))) 607 return ERR_PTR(-EFAULT); 608 if (!mq_attr_ok(&attr)) 609 return ERR_PTR(-EINVAL); 610 /* store for use during create */ 611 dentry->d_fsdata = &attr; 612 } 613 614 mode &= ~current->fs->umask; 615 ret = vfs_create(dir->d_inode, dentry, mode, NULL); 616 dentry->d_fsdata = NULL; 617 if (ret) 618 return ERR_PTR(ret); 619 620 filp = dentry_open(dentry, mqueue_mnt, oflag); 621 if (!IS_ERR(filp)) 622 dget(dentry); 623 624 return filp; 625} 626 627/* Opens existing queue */ 628static struct file *do_open(struct dentry *dentry, int oflag) 629{ 630static int oflag2acc[O_ACCMODE] = { MAY_READ, MAY_WRITE, 631 MAY_READ | MAY_WRITE }; 632 struct file *filp; 633 634 if ((oflag & O_ACCMODE) == (O_RDWR | O_WRONLY)) 635 return ERR_PTR(-EINVAL); 636 637 if (permission(dentry->d_inode, oflag2acc[oflag & O_ACCMODE], NULL)) 638 return ERR_PTR(-EACCES); 639 640 filp = dentry_open(dentry, mqueue_mnt, oflag); 641 642 if (!IS_ERR(filp)) 643 dget(dentry); 644 645 return filp; 646} 647 648asmlinkage long sys_mq_open(const char __user *u_name, int oflag, mode_t mode, 649 struct mq_attr __user *u_attr) 650{ 651 struct dentry *dentry; 652 struct file *filp; 653 char *name; 654 int fd, error; 655 656 if (IS_ERR(name = getname(u_name))) 657 return PTR_ERR(name); 658 659 fd = get_unused_fd(); 660 if (fd < 0) 661 goto out_putname; 662 663 mutex_lock(&mqueue_mnt->mnt_root->d_inode->i_mutex); 664 dentry = lookup_one_len(name, mqueue_mnt->mnt_root, strlen(name)); 665 if (IS_ERR(dentry)) { 666 error = PTR_ERR(dentry); 667 goto out_err; 668 } 669 mntget(mqueue_mnt); 670 671 if (oflag & O_CREAT) { 672 if (dentry->d_inode) { /* entry already exists */ 673 filp = (oflag & O_EXCL) ? ERR_PTR(-EEXIST) : 674 do_open(dentry, oflag); 675 } else { 676 filp = do_create(mqueue_mnt->mnt_root, dentry, 677 oflag, mode, u_attr); 678 } 679 } else 680 filp = (dentry->d_inode) ? do_open(dentry, oflag) : 681 ERR_PTR(-ENOENT); 682 683 dput(dentry); 684 685 if (IS_ERR(filp)) { 686 error = PTR_ERR(filp); 687 goto out_putfd; 688 } 689 690 set_close_on_exec(fd, 1); 691 fd_install(fd, filp); 692 goto out_upsem; 693 694out_putfd: 695 mntput(mqueue_mnt); 696 put_unused_fd(fd); 697out_err: 698 fd = error; 699out_upsem: 700 mutex_unlock(&mqueue_mnt->mnt_root->d_inode->i_mutex); 701out_putname: 702 putname(name); 703 return fd; 704} 705 706asmlinkage long sys_mq_unlink(const char __user *u_name) 707{ 708 int err; 709 char *name; 710 struct dentry *dentry; 711 struct inode *inode = NULL; 712 713 name = getname(u_name); 714 if (IS_ERR(name)) 715 return PTR_ERR(name); 716 717 mutex_lock(&mqueue_mnt->mnt_root->d_inode->i_mutex); 718 dentry = lookup_one_len(name, mqueue_mnt->mnt_root, strlen(name)); 719 if (IS_ERR(dentry)) { 720 err = PTR_ERR(dentry); 721 goto out_unlock; 722 } 723 724 if (!dentry->d_inode) { 725 err = -ENOENT; 726 goto out_err; 727 } 728 729 inode = dentry->d_inode; 730 if (inode) 731 atomic_inc(&inode->i_count); 732 733 err = vfs_unlink(dentry->d_parent->d_inode, dentry); 734out_err: 735 dput(dentry); 736 737out_unlock: 738 mutex_unlock(&mqueue_mnt->mnt_root->d_inode->i_mutex); 739 putname(name); 740 if (inode) 741 iput(inode); 742 743 return err; 744} 745 746/* Pipelined send and receive functions. 747 * 748 * If a receiver finds no waiting message, then it registers itself in the 749 * list of waiting receivers. A sender checks that list before adding the new 750 * message into the message array. If there is a waiting receiver, then it 751 * bypasses the message array and directly hands the message over to the 752 * receiver. 753 * The receiver accepts the message and returns without grabbing the queue 754 * spinlock. Therefore an intermediate STATE_PENDING state and memory barriers 755 * are necessary. The same algorithm is used for sysv semaphores, see 756 * ipc/sem.c fore more details. 757 * 758 * The same algorithm is used for senders. 759 */ 760 761/* pipelined_send() - send a message directly to the task waiting in 762 * sys_mq_timedreceive() (without inserting message into a queue). 763 */ 764static inline void pipelined_send(struct mqueue_inode_info *info, 765 struct msg_msg *message, 766 struct ext_wait_queue *receiver) 767{ 768 receiver->msg = message; 769 list_del(&receiver->list); 770 receiver->state = STATE_PENDING; 771 wake_up_process(receiver->task); 772 smp_wmb(); 773 receiver->state = STATE_READY; 774} 775 776/* pipelined_receive() - if there is task waiting in sys_mq_timedsend() 777 * gets its message and put to the queue (we have one free place for sure). */ 778static inline void pipelined_receive(struct mqueue_inode_info *info) 779{ 780 struct ext_wait_queue *sender = wq_get_first_waiter(info, SEND); 781 782 if (!sender) { 783 /* for poll */ 784 wake_up_interruptible(&info->wait_q); 785 return; 786 } 787 msg_insert(sender->msg, info); 788 list_del(&sender->list); 789 sender->state = STATE_PENDING; 790 wake_up_process(sender->task); 791 smp_wmb(); 792 sender->state = STATE_READY; 793} 794 795asmlinkage long sys_mq_timedsend(mqd_t mqdes, const char __user *u_msg_ptr, 796 size_t msg_len, unsigned int msg_prio, 797 const struct timespec __user *u_abs_timeout) 798{ 799 struct file *filp; 800 struct inode *inode; 801 struct ext_wait_queue wait; 802 struct ext_wait_queue *receiver; 803 struct msg_msg *msg_ptr; 804 struct mqueue_inode_info *info; 805 long timeout; 806 int ret; 807 808 if (unlikely(msg_prio >= (unsigned long) MQ_PRIO_MAX)) 809 return -EINVAL; 810 811 timeout = prepare_timeout(u_abs_timeout); 812 813 ret = -EBADF; 814 filp = fget(mqdes); 815 if (unlikely(!filp)) 816 goto out; 817 818 inode = filp->f_dentry->d_inode; 819 if (unlikely(filp->f_op != &mqueue_file_operations)) 820 goto out_fput; 821 info = MQUEUE_I(inode); 822 823 if (unlikely(!(filp->f_mode & FMODE_WRITE))) 824 goto out_fput; 825 826 if (unlikely(msg_len > info->attr.mq_msgsize)) { 827 ret = -EMSGSIZE; 828 goto out_fput; 829 } 830 831 /* First try to allocate memory, before doing anything with 832 * existing queues. */ 833 msg_ptr = load_msg(u_msg_ptr, msg_len); 834 if (IS_ERR(msg_ptr)) { 835 ret = PTR_ERR(msg_ptr); 836 goto out_fput; 837 } 838 msg_ptr->m_ts = msg_len; 839 msg_ptr->m_type = msg_prio; 840 841 spin_lock(&info->lock); 842 843 if (info->attr.mq_curmsgs == info->attr.mq_maxmsg) { 844 if (filp->f_flags & O_NONBLOCK) { 845 spin_unlock(&info->lock); 846 ret = -EAGAIN; 847 } else if (unlikely(timeout < 0)) { 848 spin_unlock(&info->lock); 849 ret = timeout; 850 } else { 851 wait.task = current; 852 wait.msg = (void *) msg_ptr; 853 wait.state = STATE_NONE; 854 ret = wq_sleep(info, SEND, timeout, &wait); 855 } 856 if (ret < 0) 857 free_msg(msg_ptr); 858 } else { 859 receiver = wq_get_first_waiter(info, RECV); 860 if (receiver) { 861 pipelined_send(info, msg_ptr, receiver); 862 } else { 863 /* adds message to the queue */ 864 msg_insert(msg_ptr, info); 865 __do_notify(info); 866 } 867 inode->i_atime = inode->i_mtime = inode->i_ctime = 868 CURRENT_TIME; 869 spin_unlock(&info->lock); 870 ret = 0; 871 } 872out_fput: 873 fput(filp); 874out: 875 return ret; 876} 877 878asmlinkage ssize_t sys_mq_timedreceive(mqd_t mqdes, char __user *u_msg_ptr, 879 size_t msg_len, unsigned int __user *u_msg_prio, 880 const struct timespec __user *u_abs_timeout) 881{ 882 long timeout; 883 ssize_t ret; 884 struct msg_msg *msg_ptr; 885 struct file *filp; 886 struct inode *inode; 887 struct mqueue_inode_info *info; 888 struct ext_wait_queue wait; 889 890 timeout = prepare_timeout(u_abs_timeout); 891 892 ret = -EBADF; 893 filp = fget(mqdes); 894 if (unlikely(!filp)) 895 goto out; 896 897 inode = filp->f_dentry->d_inode; 898 if (unlikely(filp->f_op != &mqueue_file_operations)) 899 goto out_fput; 900 info = MQUEUE_I(inode); 901 902 if (unlikely(!(filp->f_mode & FMODE_READ))) 903 goto out_fput; 904 905 /* checks if buffer is big enough */ 906 if (unlikely(msg_len < info->attr.mq_msgsize)) { 907 ret = -EMSGSIZE; 908 goto out_fput; 909 } 910 911 spin_lock(&info->lock); 912 if (info->attr.mq_curmsgs == 0) { 913 if (filp->f_flags & O_NONBLOCK) { 914 spin_unlock(&info->lock); 915 ret = -EAGAIN; 916 msg_ptr = NULL; 917 } else if (unlikely(timeout < 0)) { 918 spin_unlock(&info->lock); 919 ret = timeout; 920 msg_ptr = NULL; 921 } else { 922 wait.task = current; 923 wait.state = STATE_NONE; 924 ret = wq_sleep(info, RECV, timeout, &wait); 925 msg_ptr = wait.msg; 926 } 927 } else { 928 msg_ptr = msg_get(info); 929 930 inode->i_atime = inode->i_mtime = inode->i_ctime = 931 CURRENT_TIME; 932 933 /* There is now free space in queue. */ 934 pipelined_receive(info); 935 spin_unlock(&info->lock); 936 ret = 0; 937 } 938 if (ret == 0) { 939 ret = msg_ptr->m_ts; 940 941 if ((u_msg_prio && put_user(msg_ptr->m_type, u_msg_prio)) || 942 store_msg(u_msg_ptr, msg_ptr, msg_ptr->m_ts)) { 943 ret = -EFAULT; 944 } 945 free_msg(msg_ptr); 946 } 947out_fput: 948 fput(filp); 949out: 950 return ret; 951} 952 953/* 954 * Notes: the case when user wants us to deregister (with NULL as pointer) 955 * and he isn't currently owner of notification, will be silently discarded. 956 * It isn't explicitly defined in the POSIX. 957 */ 958asmlinkage long sys_mq_notify(mqd_t mqdes, 959 const struct sigevent __user *u_notification) 960{ 961 int ret; 962 struct file *filp; 963 struct sock *sock; 964 struct inode *inode; 965 struct sigevent notification; 966 struct mqueue_inode_info *info; 967 struct sk_buff *nc; 968 969 nc = NULL; 970 sock = NULL; 971 if (u_notification != NULL) { 972 if (copy_from_user(¬ification, u_notification, 973 sizeof(struct sigevent))) 974 return -EFAULT; 975 976 if (unlikely(notification.sigev_notify != SIGEV_NONE && 977 notification.sigev_notify != SIGEV_SIGNAL && 978 notification.sigev_notify != SIGEV_THREAD)) 979 return -EINVAL; 980 if (notification.sigev_notify == SIGEV_SIGNAL && 981 !valid_signal(notification.sigev_signo)) { 982 return -EINVAL; 983 } 984 if (notification.sigev_notify == SIGEV_THREAD) { 985 /* create the notify skb */ 986 nc = alloc_skb(NOTIFY_COOKIE_LEN, GFP_KERNEL); 987 ret = -ENOMEM; 988 if (!nc) 989 goto out; 990 ret = -EFAULT; 991 if (copy_from_user(nc->data, 992 notification.sigev_value.sival_ptr, 993 NOTIFY_COOKIE_LEN)) { 994 goto out; 995 } 996 997 /* TODO: add a header? */ 998 skb_put(nc, NOTIFY_COOKIE_LEN); 999 /* and attach it to the socket */ 1000retry: 1001 filp = fget(notification.sigev_signo); 1002 ret = -EBADF; 1003 if (!filp) 1004 goto out; 1005 sock = netlink_getsockbyfilp(filp); 1006 fput(filp); 1007 if (IS_ERR(sock)) { 1008 ret = PTR_ERR(sock); 1009 sock = NULL; 1010 goto out; 1011 } 1012 1013 ret = netlink_attachskb(sock, nc, 0, MAX_SCHEDULE_TIMEOUT); 1014 if (ret == 1) 1015 goto retry; 1016 if (ret) { 1017 sock = NULL; 1018 nc = NULL; 1019 goto out; 1020 } 1021 } 1022 } 1023 1024 ret = -EBADF; 1025 filp = fget(mqdes); 1026 if (!filp) 1027 goto out; 1028 1029 inode = filp->f_dentry->d_inode; 1030 if (unlikely(filp->f_op != &mqueue_file_operations)) 1031 goto out_fput; 1032 info = MQUEUE_I(inode); 1033 1034 ret = 0; 1035 spin_lock(&info->lock); 1036 if (u_notification == NULL) { 1037 if (info->notify_owner == current->tgid) { 1038 remove_notification(info); 1039 inode->i_atime = inode->i_ctime = CURRENT_TIME; 1040 } 1041 } else if (info->notify_owner != 0) { 1042 ret = -EBUSY; 1043 } else { 1044 switch (notification.sigev_notify) { 1045 case SIGEV_NONE: 1046 info->notify.sigev_notify = SIGEV_NONE; 1047 break; 1048 case SIGEV_THREAD: 1049 info->notify_sock = sock; 1050 info->notify_cookie = nc; 1051 sock = NULL; 1052 nc = NULL; 1053 info->notify.sigev_notify = SIGEV_THREAD; 1054 break; 1055 case SIGEV_SIGNAL: 1056 info->notify.sigev_signo = notification.sigev_signo; 1057 info->notify.sigev_value = notification.sigev_value; 1058 info->notify.sigev_notify = SIGEV_SIGNAL; 1059 break; 1060 } 1061 info->notify_owner = current->tgid; 1062 inode->i_atime = inode->i_ctime = CURRENT_TIME; 1063 } 1064 spin_unlock(&info->lock); 1065out_fput: 1066 fput(filp); 1067out: 1068 if (sock) { 1069 netlink_detachskb(sock, nc); 1070 } else if (nc) { 1071 dev_kfree_skb(nc); 1072 } 1073 return ret; 1074} 1075 1076asmlinkage long sys_mq_getsetattr(mqd_t mqdes, 1077 const struct mq_attr __user *u_mqstat, 1078 struct mq_attr __user *u_omqstat) 1079{ 1080 int ret; 1081 struct mq_attr mqstat, omqstat; 1082 struct file *filp; 1083 struct inode *inode; 1084 struct mqueue_inode_info *info; 1085 1086 if (u_mqstat != NULL) { 1087 if (copy_from_user(&mqstat, u_mqstat, sizeof(struct mq_attr))) 1088 return -EFAULT; 1089 if (mqstat.mq_flags & (~O_NONBLOCK)) 1090 return -EINVAL; 1091 } 1092 1093 ret = -EBADF; 1094 filp = fget(mqdes); 1095 if (!filp) 1096 goto out; 1097 1098 inode = filp->f_dentry->d_inode; 1099 if (unlikely(filp->f_op != &mqueue_file_operations)) 1100 goto out_fput; 1101 info = MQUEUE_I(inode); 1102 1103 spin_lock(&info->lock); 1104 1105 omqstat = info->attr; 1106 omqstat.mq_flags = filp->f_flags & O_NONBLOCK; 1107 if (u_mqstat) { 1108 if (mqstat.mq_flags & O_NONBLOCK) 1109 filp->f_flags |= O_NONBLOCK; 1110 else 1111 filp->f_flags &= ~O_NONBLOCK; 1112 1113 inode->i_atime = inode->i_ctime = CURRENT_TIME; 1114 } 1115 1116 spin_unlock(&info->lock); 1117 1118 ret = 0; 1119 if (u_omqstat != NULL && copy_to_user(u_omqstat, &omqstat, 1120 sizeof(struct mq_attr))) 1121 ret = -EFAULT; 1122 1123out_fput: 1124 fput(filp); 1125out: 1126 return ret; 1127} 1128 1129static struct inode_operations mqueue_dir_inode_operations = { 1130 .lookup = simple_lookup, 1131 .create = mqueue_create, 1132 .unlink = mqueue_unlink, 1133}; 1134 1135static struct file_operations mqueue_file_operations = { 1136 .flush = mqueue_flush_file, 1137 .poll = mqueue_poll_file, 1138 .read = mqueue_read_file, 1139}; 1140 1141static struct super_operations mqueue_super_ops = { 1142 .alloc_inode = mqueue_alloc_inode, 1143 .destroy_inode = mqueue_destroy_inode, 1144 .statfs = simple_statfs, 1145 .delete_inode = mqueue_delete_inode, 1146 .drop_inode = generic_delete_inode, 1147}; 1148 1149static struct file_system_type mqueue_fs_type = { 1150 .name = "mqueue", 1151 .get_sb = mqueue_get_sb, 1152 .kill_sb = kill_litter_super, 1153}; 1154 1155static int msg_max_limit_min = DFLT_MSGMAX; 1156static int msg_max_limit_max = HARD_MSGMAX; 1157 1158static int msg_maxsize_limit_min = DFLT_MSGSIZEMAX; 1159static int msg_maxsize_limit_max = INT_MAX; 1160 1161static ctl_table mq_sysctls[] = { 1162 { 1163 .ctl_name = CTL_QUEUESMAX, 1164 .procname = "queues_max", 1165 .data = &queues_max, 1166 .maxlen = sizeof(int), 1167 .mode = 0644, 1168 .proc_handler = &proc_dointvec, 1169 }, 1170 { 1171 .ctl_name = CTL_MSGMAX, 1172 .procname = "msg_max", 1173 .data = &msg_max, 1174 .maxlen = sizeof(int), 1175 .mode = 0644, 1176 .proc_handler = &proc_dointvec_minmax, 1177 .extra1 = &msg_max_limit_min, 1178 .extra2 = &msg_max_limit_max, 1179 }, 1180 { 1181 .ctl_name = CTL_MSGSIZEMAX, 1182 .procname = "msgsize_max", 1183 .data = &msgsize_max, 1184 .maxlen = sizeof(int), 1185 .mode = 0644, 1186 .proc_handler = &proc_dointvec_minmax, 1187 .extra1 = &msg_maxsize_limit_min, 1188 .extra2 = &msg_maxsize_limit_max, 1189 }, 1190 { .ctl_name = 0 } 1191}; 1192 1193static ctl_table mq_sysctl_dir[] = { 1194 { 1195 .ctl_name = FS_MQUEUE, 1196 .procname = "mqueue", 1197 .mode = 0555, 1198 .child = mq_sysctls, 1199 }, 1200 { .ctl_name = 0 } 1201}; 1202 1203static ctl_table mq_sysctl_root[] = { 1204 { 1205 .ctl_name = CTL_FS, 1206 .procname = "fs", 1207 .mode = 0555, 1208 .child = mq_sysctl_dir, 1209 }, 1210 { .ctl_name = 0 } 1211}; 1212 1213static int __init init_mqueue_fs(void) 1214{ 1215 int error; 1216 1217 mqueue_inode_cachep = kmem_cache_create("mqueue_inode_cache", 1218 sizeof(struct mqueue_inode_info), 0, 1219 SLAB_HWCACHE_ALIGN, init_once, NULL); 1220 if (mqueue_inode_cachep == NULL) 1221 return -ENOMEM; 1222 1223 /* ignore failues - they are not fatal */ 1224 mq_sysctl_table = register_sysctl_table(mq_sysctl_root, 0); 1225 1226 error = register_filesystem(&mqueue_fs_type); 1227 if (error) 1228 goto out_sysctl; 1229 1230 if (IS_ERR(mqueue_mnt = kern_mount(&mqueue_fs_type))) { 1231 error = PTR_ERR(mqueue_mnt); 1232 goto out_filesystem; 1233 } 1234 1235 /* internal initialization - not common for vfs */ 1236 queues_count = 0; 1237 spin_lock_init(&mq_lock); 1238 1239 return 0; 1240 1241out_filesystem: 1242 unregister_filesystem(&mqueue_fs_type); 1243out_sysctl: 1244 if (mq_sysctl_table) 1245 unregister_sysctl_table(mq_sysctl_table); 1246 if (kmem_cache_destroy(mqueue_inode_cachep)) { 1247 printk(KERN_INFO 1248 "mqueue_inode_cache: not all structures were freed\n"); 1249 } 1250 return error; 1251} 1252 1253__initcall(init_mqueue_fs); 1254