mqueue.c revision 0622753b800e4cc6cb9319b36b27658c72dd7cdc
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 56struct ext_wait_queue { /* queue of sleeping tasks */ 57 struct task_struct *task; 58 struct list_head list; 59 struct msg_msg *msg; /* ptr of loaded message */ 60 int state; /* one of STATE_* values */ 61}; 62 63struct mqueue_inode_info { 64 spinlock_t lock; 65 struct inode vfs_inode; 66 wait_queue_head_t wait_q; 67 68 struct msg_msg **messages; 69 struct mq_attr attr; 70 71 struct sigevent notify; 72 struct pid* notify_owner; 73 struct user_struct *user; /* user who created, for accounting */ 74 struct sock *notify_sock; 75 struct sk_buff *notify_cookie; 76 77 /* for tasks waiting for free space and messages, respectively */ 78 struct ext_wait_queue e_wait_q[2]; 79 80 unsigned long qsize; /* size of queue in memory (sum of all msgs) */ 81}; 82 83static const struct inode_operations mqueue_dir_inode_operations; 84static const struct file_operations mqueue_file_operations; 85static struct super_operations mqueue_super_ops; 86static void remove_notification(struct mqueue_inode_info *info); 87 88static spinlock_t mq_lock; 89static struct kmem_cache *mqueue_inode_cachep; 90static struct vfsmount *mqueue_mnt; 91 92static unsigned int queues_count; 93static unsigned int queues_max = DFLT_QUEUESMAX; 94static unsigned int msg_max = DFLT_MSGMAX; 95static unsigned int msgsize_max = DFLT_MSGSIZEMAX; 96 97static struct ctl_table_header * mq_sysctl_table; 98 99static inline struct mqueue_inode_info *MQUEUE_I(struct inode *inode) 100{ 101 return container_of(inode, struct mqueue_inode_info, vfs_inode); 102} 103 104static struct inode *mqueue_get_inode(struct super_block *sb, int mode, 105 struct mq_attr *attr) 106{ 107 struct inode *inode; 108 109 inode = new_inode(sb); 110 if (inode) { 111 inode->i_mode = mode; 112 inode->i_uid = current->fsuid; 113 inode->i_gid = current->fsgid; 114 inode->i_blocks = 0; 115 inode->i_mtime = inode->i_ctime = inode->i_atime = 116 CURRENT_TIME; 117 118 if (S_ISREG(mode)) { 119 struct mqueue_inode_info *info; 120 struct task_struct *p = current; 121 struct user_struct *u = p->user; 122 unsigned long mq_bytes, mq_msg_tblsz; 123 124 inode->i_fop = &mqueue_file_operations; 125 inode->i_size = FILENT_SIZE; 126 /* mqueue specific info */ 127 info = MQUEUE_I(inode); 128 spin_lock_init(&info->lock); 129 init_waitqueue_head(&info->wait_q); 130 INIT_LIST_HEAD(&info->e_wait_q[0].list); 131 INIT_LIST_HEAD(&info->e_wait_q[1].list); 132 info->messages = NULL; 133 info->notify_owner = NULL; 134 info->qsize = 0; 135 info->user = NULL; /* set when all is ok */ 136 memset(&info->attr, 0, sizeof(info->attr)); 137 info->attr.mq_maxmsg = DFLT_MSGMAX; 138 info->attr.mq_msgsize = DFLT_MSGSIZEMAX; 139 if (attr) { 140 info->attr.mq_maxmsg = attr->mq_maxmsg; 141 info->attr.mq_msgsize = attr->mq_msgsize; 142 } 143 mq_msg_tblsz = info->attr.mq_maxmsg * sizeof(struct msg_msg *); 144 mq_bytes = (mq_msg_tblsz + 145 (info->attr.mq_maxmsg * info->attr.mq_msgsize)); 146 147 spin_lock(&mq_lock); 148 if (u->mq_bytes + mq_bytes < u->mq_bytes || 149 u->mq_bytes + mq_bytes > 150 p->signal->rlim[RLIMIT_MSGQUEUE].rlim_cur) { 151 spin_unlock(&mq_lock); 152 goto out_inode; 153 } 154 u->mq_bytes += mq_bytes; 155 spin_unlock(&mq_lock); 156 157 info->messages = kmalloc(mq_msg_tblsz, GFP_KERNEL); 158 if (!info->messages) { 159 spin_lock(&mq_lock); 160 u->mq_bytes -= mq_bytes; 161 spin_unlock(&mq_lock); 162 goto out_inode; 163 } 164 /* all is ok */ 165 info->user = get_uid(u); 166 } else if (S_ISDIR(mode)) { 167 inc_nlink(inode); 168 /* Some things misbehave if size == 0 on a directory */ 169 inode->i_size = 2 * DIRENT_SIZE; 170 inode->i_op = &mqueue_dir_inode_operations; 171 inode->i_fop = &simple_dir_operations; 172 } 173 } 174 return inode; 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 int mqueue_get_sb(struct file_system_type *fs_type, 204 int flags, const char *dev_name, 205 void *data, struct vfsmount *mnt) 206{ 207 return get_sb_single(fs_type, flags, data, mqueue_fill_super, mnt); 208} 209 210static void init_once(struct kmem_cache *cachep, void *foo) 211{ 212 struct mqueue_inode_info *p = (struct mqueue_inode_info *) foo; 213 214 inode_init_once(&p->vfs_inode); 215} 216 217static struct inode *mqueue_alloc_inode(struct super_block *sb) 218{ 219 struct mqueue_inode_info *ei; 220 221 ei = kmem_cache_alloc(mqueue_inode_cachep, GFP_KERNEL); 222 if (!ei) 223 return NULL; 224 return &ei->vfs_inode; 225} 226 227static void mqueue_destroy_inode(struct inode *inode) 228{ 229 kmem_cache_free(mqueue_inode_cachep, MQUEUE_I(inode)); 230} 231 232static void mqueue_delete_inode(struct inode *inode) 233{ 234 struct mqueue_inode_info *info; 235 struct user_struct *user; 236 unsigned long mq_bytes; 237 int i; 238 239 if (S_ISDIR(inode->i_mode)) { 240 clear_inode(inode); 241 return; 242 } 243 info = MQUEUE_I(inode); 244 spin_lock(&info->lock); 245 for (i = 0; i < info->attr.mq_curmsgs; i++) 246 free_msg(info->messages[i]); 247 kfree(info->messages); 248 spin_unlock(&info->lock); 249 250 clear_inode(inode); 251 252 mq_bytes = (info->attr.mq_maxmsg * sizeof(struct msg_msg *) + 253 (info->attr.mq_maxmsg * info->attr.mq_msgsize)); 254 user = info->user; 255 if (user) { 256 spin_lock(&mq_lock); 257 user->mq_bytes -= mq_bytes; 258 queues_count--; 259 spin_unlock(&mq_lock); 260 free_uid(user); 261 } 262} 263 264static int mqueue_create(struct inode *dir, struct dentry *dentry, 265 int mode, struct nameidata *nd) 266{ 267 struct inode *inode; 268 struct mq_attr *attr = dentry->d_fsdata; 269 int error; 270 271 spin_lock(&mq_lock); 272 if (queues_count >= queues_max && !capable(CAP_SYS_RESOURCE)) { 273 error = -ENOSPC; 274 goto out_lock; 275 } 276 queues_count++; 277 spin_unlock(&mq_lock); 278 279 inode = mqueue_get_inode(dir->i_sb, mode, attr); 280 if (!inode) { 281 error = -ENOMEM; 282 spin_lock(&mq_lock); 283 queues_count--; 284 goto out_lock; 285 } 286 287 dir->i_size += DIRENT_SIZE; 288 dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME; 289 290 d_instantiate(dentry, inode); 291 dget(dentry); 292 return 0; 293out_lock: 294 spin_unlock(&mq_lock); 295 return error; 296} 297 298static int mqueue_unlink(struct inode *dir, struct dentry *dentry) 299{ 300 struct inode *inode = dentry->d_inode; 301 302 dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME; 303 dir->i_size -= DIRENT_SIZE; 304 drop_nlink(inode); 305 dput(dentry); 306 return 0; 307} 308 309/* 310* This is routine for system read from queue file. 311* To avoid mess with doing here some sort of mq_receive we allow 312* to read only queue size & notification info (the only values 313* that are interesting from user point of view and aren't accessible 314* through std routines) 315*/ 316static ssize_t mqueue_read_file(struct file *filp, char __user *u_data, 317 size_t count, loff_t * off) 318{ 319 struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode); 320 char buffer[FILENT_SIZE]; 321 size_t slen; 322 loff_t o; 323 324 if (!count) 325 return 0; 326 327 spin_lock(&info->lock); 328 snprintf(buffer, sizeof(buffer), 329 "QSIZE:%-10lu NOTIFY:%-5d SIGNO:%-5d NOTIFY_PID:%-6d\n", 330 info->qsize, 331 info->notify_owner ? info->notify.sigev_notify : 0, 332 (info->notify_owner && 333 info->notify.sigev_notify == SIGEV_SIGNAL) ? 334 info->notify.sigev_signo : 0, 335 pid_vnr(info->notify_owner)); 336 spin_unlock(&info->lock); 337 buffer[sizeof(buffer)-1] = '\0'; 338 slen = strlen(buffer)+1; 339 340 o = *off; 341 if (o > slen) 342 return 0; 343 344 if (o + count > slen) 345 count = slen - o; 346 347 if (copy_to_user(u_data, buffer + o, count)) 348 return -EFAULT; 349 350 *off = o + count; 351 filp->f_path.dentry->d_inode->i_atime = filp->f_path.dentry->d_inode->i_ctime = CURRENT_TIME; 352 return count; 353} 354 355static int mqueue_flush_file(struct file *filp, fl_owner_t id) 356{ 357 struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode); 358 359 spin_lock(&info->lock); 360 if (task_tgid(current) == info->notify_owner) 361 remove_notification(info); 362 363 spin_unlock(&info->lock); 364 return 0; 365} 366 367static unsigned int mqueue_poll_file(struct file *filp, struct poll_table_struct *poll_tab) 368{ 369 struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode); 370 int retval = 0; 371 372 poll_wait(filp, &info->wait_q, poll_tab); 373 374 spin_lock(&info->lock); 375 if (info->attr.mq_curmsgs) 376 retval = POLLIN | POLLRDNORM; 377 378 if (info->attr.mq_curmsgs < info->attr.mq_maxmsg) 379 retval |= POLLOUT | POLLWRNORM; 380 spin_unlock(&info->lock); 381 382 return retval; 383} 384 385/* Adds current to info->e_wait_q[sr] before element with smaller prio */ 386static void wq_add(struct mqueue_inode_info *info, int sr, 387 struct ext_wait_queue *ewp) 388{ 389 struct ext_wait_queue *walk; 390 391 ewp->task = current; 392 393 list_for_each_entry(walk, &info->e_wait_q[sr].list, list) { 394 if (walk->task->static_prio <= current->static_prio) { 395 list_add_tail(&ewp->list, &walk->list); 396 return; 397 } 398 } 399 list_add_tail(&ewp->list, &info->e_wait_q[sr].list); 400} 401 402/* 403 * Puts current task to sleep. Caller must hold queue lock. After return 404 * lock isn't held. 405 * sr: SEND or RECV 406 */ 407static int wq_sleep(struct mqueue_inode_info *info, int sr, 408 long timeout, struct ext_wait_queue *ewp) 409{ 410 int retval; 411 signed long time; 412 413 wq_add(info, sr, ewp); 414 415 for (;;) { 416 set_current_state(TASK_INTERRUPTIBLE); 417 418 spin_unlock(&info->lock); 419 time = schedule_timeout(timeout); 420 421 while (ewp->state == STATE_PENDING) 422 cpu_relax(); 423 424 if (ewp->state == STATE_READY) { 425 retval = 0; 426 goto out; 427 } 428 spin_lock(&info->lock); 429 if (ewp->state == STATE_READY) { 430 retval = 0; 431 goto out_unlock; 432 } 433 if (signal_pending(current)) { 434 retval = -ERESTARTSYS; 435 break; 436 } 437 if (time == 0) { 438 retval = -ETIMEDOUT; 439 break; 440 } 441 } 442 list_del(&ewp->list); 443out_unlock: 444 spin_unlock(&info->lock); 445out: 446 return retval; 447} 448 449/* 450 * Returns waiting task that should be serviced first or NULL if none exists 451 */ 452static struct ext_wait_queue *wq_get_first_waiter( 453 struct mqueue_inode_info *info, int sr) 454{ 455 struct list_head *ptr; 456 457 ptr = info->e_wait_q[sr].list.prev; 458 if (ptr == &info->e_wait_q[sr].list) 459 return NULL; 460 return list_entry(ptr, struct ext_wait_queue, list); 461} 462 463/* Auxiliary functions to manipulate messages' list */ 464static void msg_insert(struct msg_msg *ptr, struct mqueue_inode_info *info) 465{ 466 int k; 467 468 k = info->attr.mq_curmsgs - 1; 469 while (k >= 0 && info->messages[k]->m_type >= ptr->m_type) { 470 info->messages[k + 1] = info->messages[k]; 471 k--; 472 } 473 info->attr.mq_curmsgs++; 474 info->qsize += ptr->m_ts; 475 info->messages[k + 1] = ptr; 476} 477 478static inline struct msg_msg *msg_get(struct mqueue_inode_info *info) 479{ 480 info->qsize -= info->messages[--info->attr.mq_curmsgs]->m_ts; 481 return info->messages[info->attr.mq_curmsgs]; 482} 483 484static inline void set_cookie(struct sk_buff *skb, char code) 485{ 486 ((char*)skb->data)[NOTIFY_COOKIE_LEN-1] = code; 487} 488 489/* 490 * The next function is only to split too long sys_mq_timedsend 491 */ 492static void __do_notify(struct mqueue_inode_info *info) 493{ 494 /* notification 495 * invoked when there is registered process and there isn't process 496 * waiting synchronously for message AND state of queue changed from 497 * empty to not empty. Here we are sure that no one is waiting 498 * synchronously. */ 499 if (info->notify_owner && 500 info->attr.mq_curmsgs == 1) { 501 struct siginfo sig_i; 502 switch (info->notify.sigev_notify) { 503 case SIGEV_NONE: 504 break; 505 case SIGEV_SIGNAL: 506 /* sends signal */ 507 508 sig_i.si_signo = info->notify.sigev_signo; 509 sig_i.si_errno = 0; 510 sig_i.si_code = SI_MESGQ; 511 sig_i.si_value = info->notify.sigev_value; 512 sig_i.si_pid = task_tgid_vnr(current); 513 sig_i.si_uid = current->uid; 514 515 kill_pid_info(info->notify.sigev_signo, 516 &sig_i, info->notify_owner); 517 break; 518 case SIGEV_THREAD: 519 set_cookie(info->notify_cookie, NOTIFY_WOKENUP); 520 netlink_sendskb(info->notify_sock, info->notify_cookie); 521 break; 522 } 523 /* after notification unregisters process */ 524 put_pid(info->notify_owner); 525 info->notify_owner = NULL; 526 } 527 wake_up(&info->wait_q); 528} 529 530static long prepare_timeout(const struct timespec __user *u_arg) 531{ 532 struct timespec ts, nowts; 533 long timeout; 534 535 if (u_arg) { 536 if (unlikely(copy_from_user(&ts, u_arg, 537 sizeof(struct timespec)))) 538 return -EFAULT; 539 540 if (unlikely(ts.tv_nsec < 0 || ts.tv_sec < 0 541 || ts.tv_nsec >= NSEC_PER_SEC)) 542 return -EINVAL; 543 nowts = CURRENT_TIME; 544 /* first subtract as jiffies can't be too big */ 545 ts.tv_sec -= nowts.tv_sec; 546 if (ts.tv_nsec < nowts.tv_nsec) { 547 ts.tv_nsec += NSEC_PER_SEC; 548 ts.tv_sec--; 549 } 550 ts.tv_nsec -= nowts.tv_nsec; 551 if (ts.tv_sec < 0) 552 return 0; 553 554 timeout = timespec_to_jiffies(&ts) + 1; 555 } else 556 return MAX_SCHEDULE_TIMEOUT; 557 558 return timeout; 559} 560 561static void remove_notification(struct mqueue_inode_info *info) 562{ 563 if (info->notify_owner != NULL && 564 info->notify.sigev_notify == SIGEV_THREAD) { 565 set_cookie(info->notify_cookie, NOTIFY_REMOVED); 566 netlink_sendskb(info->notify_sock, info->notify_cookie); 567 } 568 put_pid(info->notify_owner); 569 info->notify_owner = NULL; 570} 571 572static int mq_attr_ok(struct mq_attr *attr) 573{ 574 if (attr->mq_maxmsg <= 0 || attr->mq_msgsize <= 0) 575 return 0; 576 if (capable(CAP_SYS_RESOURCE)) { 577 if (attr->mq_maxmsg > HARD_MSGMAX) 578 return 0; 579 } else { 580 if (attr->mq_maxmsg > msg_max || 581 attr->mq_msgsize > msgsize_max) 582 return 0; 583 } 584 /* check for overflow */ 585 if (attr->mq_msgsize > ULONG_MAX/attr->mq_maxmsg) 586 return 0; 587 if ((unsigned long)(attr->mq_maxmsg * attr->mq_msgsize) + 588 (attr->mq_maxmsg * sizeof (struct msg_msg *)) < 589 (unsigned long)(attr->mq_maxmsg * attr->mq_msgsize)) 590 return 0; 591 return 1; 592} 593 594/* 595 * Invoked when creating a new queue via sys_mq_open 596 */ 597static struct file *do_create(struct dentry *dir, struct dentry *dentry, 598 int oflag, mode_t mode, struct mq_attr __user *u_attr) 599{ 600 struct mq_attr attr; 601 int ret; 602 603 if (u_attr) { 604 ret = -EFAULT; 605 if (copy_from_user(&attr, u_attr, sizeof(attr))) 606 goto out; 607 ret = -EINVAL; 608 if (!mq_attr_ok(&attr)) 609 goto out; 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 goto out; 619 620 return dentry_open(dentry, mqueue_mnt, oflag); 621 622out: 623 dput(dentry); 624 mntput(mqueue_mnt); 625 return ERR_PTR(ret); 626} 627 628/* Opens existing queue */ 629static struct file *do_open(struct dentry *dentry, int oflag) 630{ 631static int oflag2acc[O_ACCMODE] = { MAY_READ, MAY_WRITE, 632 MAY_READ | MAY_WRITE }; 633 634 if ((oflag & O_ACCMODE) == (O_RDWR | O_WRONLY)) { 635 dput(dentry); 636 mntput(mqueue_mnt); 637 return ERR_PTR(-EINVAL); 638 } 639 640 if (permission(dentry->d_inode, oflag2acc[oflag & O_ACCMODE], NULL)) { 641 dput(dentry); 642 mntput(mqueue_mnt); 643 return ERR_PTR(-EACCES); 644 } 645 646 return dentry_open(dentry, mqueue_mnt, oflag); 647} 648 649asmlinkage long sys_mq_open(const char __user *u_name, int oflag, mode_t mode, 650 struct mq_attr __user *u_attr) 651{ 652 struct dentry *dentry; 653 struct file *filp; 654 char *name; 655 int fd, error; 656 657 error = audit_mq_open(oflag, mode, u_attr); 658 if (error != 0) 659 return error; 660 661 if (IS_ERR(name = getname(u_name))) 662 return PTR_ERR(name); 663 664 fd = get_unused_fd(); 665 if (fd < 0) 666 goto out_putname; 667 668 mutex_lock(&mqueue_mnt->mnt_root->d_inode->i_mutex); 669 dentry = lookup_one_len(name, mqueue_mnt->mnt_root, strlen(name)); 670 if (IS_ERR(dentry)) { 671 error = PTR_ERR(dentry); 672 goto out_err; 673 } 674 mntget(mqueue_mnt); 675 676 if (oflag & O_CREAT) { 677 if (dentry->d_inode) { /* entry already exists */ 678 audit_inode(name, dentry); 679 error = -EEXIST; 680 if (oflag & O_EXCL) 681 goto out; 682 filp = do_open(dentry, oflag); 683 } else { 684 filp = do_create(mqueue_mnt->mnt_root, dentry, 685 oflag, mode, u_attr); 686 } 687 } else { 688 error = -ENOENT; 689 if (!dentry->d_inode) 690 goto out; 691 audit_inode(name, dentry); 692 filp = do_open(dentry, oflag); 693 } 694 695 if (IS_ERR(filp)) { 696 error = PTR_ERR(filp); 697 goto out_putfd; 698 } 699 700 set_close_on_exec(fd, 1); 701 fd_install(fd, filp); 702 goto out_upsem; 703 704out: 705 dput(dentry); 706 mntput(mqueue_mnt); 707out_putfd: 708 put_unused_fd(fd); 709out_err: 710 fd = error; 711out_upsem: 712 mutex_unlock(&mqueue_mnt->mnt_root->d_inode->i_mutex); 713out_putname: 714 putname(name); 715 return fd; 716} 717 718asmlinkage long sys_mq_unlink(const char __user *u_name) 719{ 720 int err; 721 char *name; 722 struct dentry *dentry; 723 struct inode *inode = NULL; 724 725 name = getname(u_name); 726 if (IS_ERR(name)) 727 return PTR_ERR(name); 728 729 mutex_lock_nested(&mqueue_mnt->mnt_root->d_inode->i_mutex, 730 I_MUTEX_PARENT); 731 dentry = lookup_one_len(name, mqueue_mnt->mnt_root, strlen(name)); 732 if (IS_ERR(dentry)) { 733 err = PTR_ERR(dentry); 734 goto out_unlock; 735 } 736 737 if (!dentry->d_inode) { 738 err = -ENOENT; 739 goto out_err; 740 } 741 742 inode = dentry->d_inode; 743 if (inode) 744 atomic_inc(&inode->i_count); 745 err = mnt_want_write(mqueue_mnt); 746 if (err) 747 goto out_err; 748 err = vfs_unlink(dentry->d_parent->d_inode, dentry); 749 mnt_drop_write(mqueue_mnt); 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_path.dentry->d_inode; 839 if (unlikely(filp->f_op != &mqueue_file_operations)) 840 goto out_fput; 841 info = MQUEUE_I(inode); 842 audit_inode(NULL, filp->f_path.dentry); 843 844 if (unlikely(!(filp->f_mode & FMODE_WRITE))) 845 goto out_fput; 846 847 if (unlikely(msg_len > info->attr.mq_msgsize)) { 848 ret = -EMSGSIZE; 849 goto out_fput; 850 } 851 852 /* First try to allocate memory, before doing anything with 853 * existing queues. */ 854 msg_ptr = load_msg(u_msg_ptr, msg_len); 855 if (IS_ERR(msg_ptr)) { 856 ret = PTR_ERR(msg_ptr); 857 goto out_fput; 858 } 859 msg_ptr->m_ts = msg_len; 860 msg_ptr->m_type = msg_prio; 861 862 spin_lock(&info->lock); 863 864 if (info->attr.mq_curmsgs == info->attr.mq_maxmsg) { 865 if (filp->f_flags & O_NONBLOCK) { 866 spin_unlock(&info->lock); 867 ret = -EAGAIN; 868 } else if (unlikely(timeout < 0)) { 869 spin_unlock(&info->lock); 870 ret = timeout; 871 } else { 872 wait.task = current; 873 wait.msg = (void *) msg_ptr; 874 wait.state = STATE_NONE; 875 ret = wq_sleep(info, SEND, timeout, &wait); 876 } 877 if (ret < 0) 878 free_msg(msg_ptr); 879 } else { 880 receiver = wq_get_first_waiter(info, RECV); 881 if (receiver) { 882 pipelined_send(info, msg_ptr, receiver); 883 } else { 884 /* adds message to the queue */ 885 msg_insert(msg_ptr, info); 886 __do_notify(info); 887 } 888 inode->i_atime = inode->i_mtime = inode->i_ctime = 889 CURRENT_TIME; 890 spin_unlock(&info->lock); 891 ret = 0; 892 } 893out_fput: 894 fput(filp); 895out: 896 return ret; 897} 898 899asmlinkage ssize_t sys_mq_timedreceive(mqd_t mqdes, char __user *u_msg_ptr, 900 size_t msg_len, unsigned int __user *u_msg_prio, 901 const struct timespec __user *u_abs_timeout) 902{ 903 long timeout; 904 ssize_t ret; 905 struct msg_msg *msg_ptr; 906 struct file *filp; 907 struct inode *inode; 908 struct mqueue_inode_info *info; 909 struct ext_wait_queue wait; 910 911 ret = audit_mq_timedreceive(mqdes, msg_len, u_msg_prio, u_abs_timeout); 912 if (ret != 0) 913 return ret; 914 915 timeout = prepare_timeout(u_abs_timeout); 916 917 ret = -EBADF; 918 filp = fget(mqdes); 919 if (unlikely(!filp)) 920 goto out; 921 922 inode = filp->f_path.dentry->d_inode; 923 if (unlikely(filp->f_op != &mqueue_file_operations)) 924 goto out_fput; 925 info = MQUEUE_I(inode); 926 audit_inode(NULL, filp->f_path.dentry); 927 928 if (unlikely(!(filp->f_mode & FMODE_READ))) 929 goto out_fput; 930 931 /* checks if buffer is big enough */ 932 if (unlikely(msg_len < info->attr.mq_msgsize)) { 933 ret = -EMSGSIZE; 934 goto out_fput; 935 } 936 937 spin_lock(&info->lock); 938 if (info->attr.mq_curmsgs == 0) { 939 if (filp->f_flags & O_NONBLOCK) { 940 spin_unlock(&info->lock); 941 ret = -EAGAIN; 942 msg_ptr = NULL; 943 } else if (unlikely(timeout < 0)) { 944 spin_unlock(&info->lock); 945 ret = timeout; 946 msg_ptr = NULL; 947 } else { 948 wait.task = current; 949 wait.state = STATE_NONE; 950 ret = wq_sleep(info, RECV, timeout, &wait); 951 msg_ptr = wait.msg; 952 } 953 } else { 954 msg_ptr = msg_get(info); 955 956 inode->i_atime = inode->i_mtime = inode->i_ctime = 957 CURRENT_TIME; 958 959 /* There is now free space in queue. */ 960 pipelined_receive(info); 961 spin_unlock(&info->lock); 962 ret = 0; 963 } 964 if (ret == 0) { 965 ret = msg_ptr->m_ts; 966 967 if ((u_msg_prio && put_user(msg_ptr->m_type, u_msg_prio)) || 968 store_msg(u_msg_ptr, msg_ptr, msg_ptr->m_ts)) { 969 ret = -EFAULT; 970 } 971 free_msg(msg_ptr); 972 } 973out_fput: 974 fput(filp); 975out: 976 return ret; 977} 978 979/* 980 * Notes: the case when user wants us to deregister (with NULL as pointer) 981 * and he isn't currently owner of notification, will be silently discarded. 982 * It isn't explicitly defined in the POSIX. 983 */ 984asmlinkage long sys_mq_notify(mqd_t mqdes, 985 const struct sigevent __user *u_notification) 986{ 987 int ret; 988 struct file *filp; 989 struct sock *sock; 990 struct inode *inode; 991 struct sigevent notification; 992 struct mqueue_inode_info *info; 993 struct sk_buff *nc; 994 995 ret = audit_mq_notify(mqdes, u_notification); 996 if (ret != 0) 997 return ret; 998 999 nc = NULL; 1000 sock = NULL; 1001 if (u_notification != NULL) { 1002 if (copy_from_user(¬ification, u_notification, 1003 sizeof(struct sigevent))) 1004 return -EFAULT; 1005 1006 if (unlikely(notification.sigev_notify != SIGEV_NONE && 1007 notification.sigev_notify != SIGEV_SIGNAL && 1008 notification.sigev_notify != SIGEV_THREAD)) 1009 return -EINVAL; 1010 if (notification.sigev_notify == SIGEV_SIGNAL && 1011 !valid_signal(notification.sigev_signo)) { 1012 return -EINVAL; 1013 } 1014 if (notification.sigev_notify == SIGEV_THREAD) { 1015 long timeo; 1016 1017 /* create the notify skb */ 1018 nc = alloc_skb(NOTIFY_COOKIE_LEN, GFP_KERNEL); 1019 ret = -ENOMEM; 1020 if (!nc) 1021 goto out; 1022 ret = -EFAULT; 1023 if (copy_from_user(nc->data, 1024 notification.sigev_value.sival_ptr, 1025 NOTIFY_COOKIE_LEN)) { 1026 goto out; 1027 } 1028 1029 /* TODO: add a header? */ 1030 skb_put(nc, NOTIFY_COOKIE_LEN); 1031 /* and attach it to the socket */ 1032retry: 1033 filp = fget(notification.sigev_signo); 1034 ret = -EBADF; 1035 if (!filp) 1036 goto out; 1037 sock = netlink_getsockbyfilp(filp); 1038 fput(filp); 1039 if (IS_ERR(sock)) { 1040 ret = PTR_ERR(sock); 1041 sock = NULL; 1042 goto out; 1043 } 1044 1045 timeo = MAX_SCHEDULE_TIMEOUT; 1046 ret = netlink_attachskb(sock, nc, 0, &timeo, NULL); 1047 if (ret == 1) 1048 goto retry; 1049 if (ret) { 1050 sock = NULL; 1051 nc = NULL; 1052 goto out; 1053 } 1054 } 1055 } 1056 1057 ret = -EBADF; 1058 filp = fget(mqdes); 1059 if (!filp) 1060 goto out; 1061 1062 inode = filp->f_path.dentry->d_inode; 1063 if (unlikely(filp->f_op != &mqueue_file_operations)) 1064 goto out_fput; 1065 info = MQUEUE_I(inode); 1066 1067 ret = 0; 1068 spin_lock(&info->lock); 1069 if (u_notification == NULL) { 1070 if (info->notify_owner == task_tgid(current)) { 1071 remove_notification(info); 1072 inode->i_atime = inode->i_ctime = CURRENT_TIME; 1073 } 1074 } else if (info->notify_owner != NULL) { 1075 ret = -EBUSY; 1076 } else { 1077 switch (notification.sigev_notify) { 1078 case SIGEV_NONE: 1079 info->notify.sigev_notify = SIGEV_NONE; 1080 break; 1081 case SIGEV_THREAD: 1082 info->notify_sock = sock; 1083 info->notify_cookie = nc; 1084 sock = NULL; 1085 nc = NULL; 1086 info->notify.sigev_notify = SIGEV_THREAD; 1087 break; 1088 case SIGEV_SIGNAL: 1089 info->notify.sigev_signo = notification.sigev_signo; 1090 info->notify.sigev_value = notification.sigev_value; 1091 info->notify.sigev_notify = SIGEV_SIGNAL; 1092 break; 1093 } 1094 1095 info->notify_owner = get_pid(task_tgid(current)); 1096 inode->i_atime = inode->i_ctime = CURRENT_TIME; 1097 } 1098 spin_unlock(&info->lock); 1099out_fput: 1100 fput(filp); 1101out: 1102 if (sock) { 1103 netlink_detachskb(sock, nc); 1104 } else if (nc) { 1105 dev_kfree_skb(nc); 1106 } 1107 return ret; 1108} 1109 1110asmlinkage long sys_mq_getsetattr(mqd_t mqdes, 1111 const struct mq_attr __user *u_mqstat, 1112 struct mq_attr __user *u_omqstat) 1113{ 1114 int ret; 1115 struct mq_attr mqstat, omqstat; 1116 struct file *filp; 1117 struct inode *inode; 1118 struct mqueue_inode_info *info; 1119 1120 if (u_mqstat != NULL) { 1121 if (copy_from_user(&mqstat, u_mqstat, sizeof(struct mq_attr))) 1122 return -EFAULT; 1123 if (mqstat.mq_flags & (~O_NONBLOCK)) 1124 return -EINVAL; 1125 } 1126 1127 ret = -EBADF; 1128 filp = fget(mqdes); 1129 if (!filp) 1130 goto out; 1131 1132 inode = filp->f_path.dentry->d_inode; 1133 if (unlikely(filp->f_op != &mqueue_file_operations)) 1134 goto out_fput; 1135 info = MQUEUE_I(inode); 1136 1137 spin_lock(&info->lock); 1138 1139 omqstat = info->attr; 1140 omqstat.mq_flags = filp->f_flags & O_NONBLOCK; 1141 if (u_mqstat) { 1142 ret = audit_mq_getsetattr(mqdes, &mqstat); 1143 if (ret != 0) { 1144 spin_unlock(&info->lock); 1145 goto out_fput; 1146 } 1147 if (mqstat.mq_flags & O_NONBLOCK) 1148 filp->f_flags |= O_NONBLOCK; 1149 else 1150 filp->f_flags &= ~O_NONBLOCK; 1151 1152 inode->i_atime = inode->i_ctime = CURRENT_TIME; 1153 } 1154 1155 spin_unlock(&info->lock); 1156 1157 ret = 0; 1158 if (u_omqstat != NULL && copy_to_user(u_omqstat, &omqstat, 1159 sizeof(struct mq_attr))) 1160 ret = -EFAULT; 1161 1162out_fput: 1163 fput(filp); 1164out: 1165 return ret; 1166} 1167 1168static const struct inode_operations mqueue_dir_inode_operations = { 1169 .lookup = simple_lookup, 1170 .create = mqueue_create, 1171 .unlink = mqueue_unlink, 1172}; 1173 1174static const struct file_operations mqueue_file_operations = { 1175 .flush = mqueue_flush_file, 1176 .poll = mqueue_poll_file, 1177 .read = mqueue_read_file, 1178}; 1179 1180static struct super_operations mqueue_super_ops = { 1181 .alloc_inode = mqueue_alloc_inode, 1182 .destroy_inode = mqueue_destroy_inode, 1183 .statfs = simple_statfs, 1184 .delete_inode = mqueue_delete_inode, 1185 .drop_inode = generic_delete_inode, 1186}; 1187 1188static struct file_system_type mqueue_fs_type = { 1189 .name = "mqueue", 1190 .get_sb = mqueue_get_sb, 1191 .kill_sb = kill_litter_super, 1192}; 1193 1194static int msg_max_limit_min = DFLT_MSGMAX; 1195static int msg_max_limit_max = HARD_MSGMAX; 1196 1197static int msg_maxsize_limit_min = DFLT_MSGSIZEMAX; 1198static int msg_maxsize_limit_max = INT_MAX; 1199 1200static ctl_table mq_sysctls[] = { 1201 { 1202 .procname = "queues_max", 1203 .data = &queues_max, 1204 .maxlen = sizeof(int), 1205 .mode = 0644, 1206 .proc_handler = &proc_dointvec, 1207 }, 1208 { 1209 .procname = "msg_max", 1210 .data = &msg_max, 1211 .maxlen = sizeof(int), 1212 .mode = 0644, 1213 .proc_handler = &proc_dointvec_minmax, 1214 .extra1 = &msg_max_limit_min, 1215 .extra2 = &msg_max_limit_max, 1216 }, 1217 { 1218 .procname = "msgsize_max", 1219 .data = &msgsize_max, 1220 .maxlen = sizeof(int), 1221 .mode = 0644, 1222 .proc_handler = &proc_dointvec_minmax, 1223 .extra1 = &msg_maxsize_limit_min, 1224 .extra2 = &msg_maxsize_limit_max, 1225 }, 1226 { .ctl_name = 0 } 1227}; 1228 1229static ctl_table mq_sysctl_dir[] = { 1230 { 1231 .procname = "mqueue", 1232 .mode = 0555, 1233 .child = mq_sysctls, 1234 }, 1235 { .ctl_name = 0 } 1236}; 1237 1238static ctl_table mq_sysctl_root[] = { 1239 { 1240 .ctl_name = CTL_FS, 1241 .procname = "fs", 1242 .mode = 0555, 1243 .child = mq_sysctl_dir, 1244 }, 1245 { .ctl_name = 0 } 1246}; 1247 1248static int __init init_mqueue_fs(void) 1249{ 1250 int error; 1251 1252 mqueue_inode_cachep = kmem_cache_create("mqueue_inode_cache", 1253 sizeof(struct mqueue_inode_info), 0, 1254 SLAB_HWCACHE_ALIGN, init_once); 1255 if (mqueue_inode_cachep == NULL) 1256 return -ENOMEM; 1257 1258 /* ignore failues - they are not fatal */ 1259 mq_sysctl_table = register_sysctl_table(mq_sysctl_root); 1260 1261 error = register_filesystem(&mqueue_fs_type); 1262 if (error) 1263 goto out_sysctl; 1264 1265 if (IS_ERR(mqueue_mnt = kern_mount(&mqueue_fs_type))) { 1266 error = PTR_ERR(mqueue_mnt); 1267 goto out_filesystem; 1268 } 1269 1270 /* internal initialization - not common for vfs */ 1271 queues_count = 0; 1272 spin_lock_init(&mq_lock); 1273 1274 return 0; 1275 1276out_filesystem: 1277 unregister_filesystem(&mqueue_fs_type); 1278out_sysctl: 1279 if (mq_sysctl_table) 1280 unregister_sysctl_table(mq_sysctl_table); 1281 kmem_cache_destroy(mqueue_inode_cachep); 1282 return error; 1283} 1284 1285__initcall(init_mqueue_fs); 1286