mqueue.c revision ba52de123d454b57369f291348266d86f4b35070
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_blocks = 0; 119 inode->i_mtime = inode->i_ctime = inode->i_atime = 120 CURRENT_TIME; 121 122 if (S_ISREG(mode)) { 123 struct mqueue_inode_info *info; 124 struct task_struct *p = current; 125 struct user_struct *u = p->user; 126 unsigned long mq_bytes, mq_msg_tblsz; 127 128 inode->i_fop = &mqueue_file_operations; 129 inode->i_size = FILENT_SIZE; 130 /* mqueue specific info */ 131 info = MQUEUE_I(inode); 132 spin_lock_init(&info->lock); 133 init_waitqueue_head(&info->wait_q); 134 INIT_LIST_HEAD(&info->e_wait_q[0].list); 135 INIT_LIST_HEAD(&info->e_wait_q[1].list); 136 info->messages = NULL; 137 info->notify_owner = 0; 138 info->qsize = 0; 139 info->user = NULL; /* set when all is ok */ 140 memset(&info->attr, 0, sizeof(info->attr)); 141 info->attr.mq_maxmsg = DFLT_MSGMAX; 142 info->attr.mq_msgsize = DFLT_MSGSIZEMAX; 143 if (attr) { 144 info->attr.mq_maxmsg = attr->mq_maxmsg; 145 info->attr.mq_msgsize = attr->mq_msgsize; 146 } 147 mq_msg_tblsz = info->attr.mq_maxmsg * sizeof(struct msg_msg *); 148 mq_bytes = (mq_msg_tblsz + 149 (info->attr.mq_maxmsg * info->attr.mq_msgsize)); 150 151 spin_lock(&mq_lock); 152 if (u->mq_bytes + mq_bytes < u->mq_bytes || 153 u->mq_bytes + mq_bytes > 154 p->signal->rlim[RLIMIT_MSGQUEUE].rlim_cur) { 155 spin_unlock(&mq_lock); 156 goto out_inode; 157 } 158 u->mq_bytes += mq_bytes; 159 spin_unlock(&mq_lock); 160 161 info->messages = kmalloc(mq_msg_tblsz, GFP_KERNEL); 162 if (!info->messages) { 163 spin_lock(&mq_lock); 164 u->mq_bytes -= mq_bytes; 165 spin_unlock(&mq_lock); 166 goto out_inode; 167 } 168 /* all is ok */ 169 info->user = get_uid(u); 170 } else if (S_ISDIR(mode)) { 171 inode->i_nlink++; 172 /* Some things misbehave if size == 0 on a directory */ 173 inode->i_size = 2 * DIRENT_SIZE; 174 inode->i_op = &mqueue_dir_inode_operations; 175 inode->i_fop = &simple_dir_operations; 176 } 177 } 178 return inode; 179out_inode: 180 make_bad_inode(inode); 181 iput(inode); 182 return NULL; 183} 184 185static int mqueue_fill_super(struct super_block *sb, void *data, int silent) 186{ 187 struct inode *inode; 188 189 sb->s_blocksize = PAGE_CACHE_SIZE; 190 sb->s_blocksize_bits = PAGE_CACHE_SHIFT; 191 sb->s_magic = MQUEUE_MAGIC; 192 sb->s_op = &mqueue_super_ops; 193 194 inode = mqueue_get_inode(sb, S_IFDIR | S_ISVTX | S_IRWXUGO, NULL); 195 if (!inode) 196 return -ENOMEM; 197 198 sb->s_root = d_alloc_root(inode); 199 if (!sb->s_root) { 200 iput(inode); 201 return -ENOMEM; 202 } 203 204 return 0; 205} 206 207static int mqueue_get_sb(struct file_system_type *fs_type, 208 int flags, const char *dev_name, 209 void *data, struct vfsmount *mnt) 210{ 211 return get_sb_single(fs_type, flags, data, mqueue_fill_super, mnt); 212} 213 214static void init_once(void *foo, kmem_cache_t * cachep, unsigned long flags) 215{ 216 struct mqueue_inode_info *p = (struct mqueue_inode_info *) foo; 217 218 if ((flags & (SLAB_CTOR_VERIFY | SLAB_CTOR_CONSTRUCTOR)) == 219 SLAB_CTOR_CONSTRUCTOR) 220 inode_init_once(&p->vfs_inode); 221} 222 223static struct inode *mqueue_alloc_inode(struct super_block *sb) 224{ 225 struct mqueue_inode_info *ei; 226 227 ei = kmem_cache_alloc(mqueue_inode_cachep, SLAB_KERNEL); 228 if (!ei) 229 return NULL; 230 return &ei->vfs_inode; 231} 232 233static void mqueue_destroy_inode(struct inode *inode) 234{ 235 kmem_cache_free(mqueue_inode_cachep, MQUEUE_I(inode)); 236} 237 238static void mqueue_delete_inode(struct inode *inode) 239{ 240 struct mqueue_inode_info *info; 241 struct user_struct *user; 242 unsigned long mq_bytes; 243 int i; 244 245 if (S_ISDIR(inode->i_mode)) { 246 clear_inode(inode); 247 return; 248 } 249 info = MQUEUE_I(inode); 250 spin_lock(&info->lock); 251 for (i = 0; i < info->attr.mq_curmsgs; i++) 252 free_msg(info->messages[i]); 253 kfree(info->messages); 254 spin_unlock(&info->lock); 255 256 clear_inode(inode); 257 258 mq_bytes = (info->attr.mq_maxmsg * sizeof(struct msg_msg *) + 259 (info->attr.mq_maxmsg * info->attr.mq_msgsize)); 260 user = info->user; 261 if (user) { 262 spin_lock(&mq_lock); 263 user->mq_bytes -= mq_bytes; 264 queues_count--; 265 spin_unlock(&mq_lock); 266 free_uid(user); 267 } 268} 269 270static int mqueue_create(struct inode *dir, struct dentry *dentry, 271 int mode, struct nameidata *nd) 272{ 273 struct inode *inode; 274 struct mq_attr *attr = dentry->d_fsdata; 275 int error; 276 277 spin_lock(&mq_lock); 278 if (queues_count >= queues_max && !capable(CAP_SYS_RESOURCE)) { 279 error = -ENOSPC; 280 goto out_lock; 281 } 282 queues_count++; 283 spin_unlock(&mq_lock); 284 285 inode = mqueue_get_inode(dir->i_sb, mode, attr); 286 if (!inode) { 287 error = -ENOMEM; 288 spin_lock(&mq_lock); 289 queues_count--; 290 goto out_lock; 291 } 292 293 dir->i_size += DIRENT_SIZE; 294 dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME; 295 296 d_instantiate(dentry, inode); 297 dget(dentry); 298 return 0; 299out_lock: 300 spin_unlock(&mq_lock); 301 return error; 302} 303 304static int mqueue_unlink(struct inode *dir, struct dentry *dentry) 305{ 306 struct inode *inode = dentry->d_inode; 307 308 dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME; 309 dir->i_size -= DIRENT_SIZE; 310 inode->i_nlink--; 311 dput(dentry); 312 return 0; 313} 314 315/* 316* This is routine for system read from queue file. 317* To avoid mess with doing here some sort of mq_receive we allow 318* to read only queue size & notification info (the only values 319* that are interesting from user point of view and aren't accessible 320* through std routines) 321*/ 322static ssize_t mqueue_read_file(struct file *filp, char __user *u_data, 323 size_t count, loff_t * off) 324{ 325 struct mqueue_inode_info *info = MQUEUE_I(filp->f_dentry->d_inode); 326 char buffer[FILENT_SIZE]; 327 size_t slen; 328 loff_t o; 329 330 if (!count) 331 return 0; 332 333 spin_lock(&info->lock); 334 snprintf(buffer, sizeof(buffer), 335 "QSIZE:%-10lu NOTIFY:%-5d SIGNO:%-5d NOTIFY_PID:%-6d\n", 336 info->qsize, 337 info->notify_owner ? info->notify.sigev_notify : 0, 338 (info->notify_owner && 339 info->notify.sigev_notify == SIGEV_SIGNAL) ? 340 info->notify.sigev_signo : 0, 341 info->notify_owner); 342 spin_unlock(&info->lock); 343 buffer[sizeof(buffer)-1] = '\0'; 344 slen = strlen(buffer)+1; 345 346 o = *off; 347 if (o > slen) 348 return 0; 349 350 if (o + count > slen) 351 count = slen - o; 352 353 if (copy_to_user(u_data, buffer + o, count)) 354 return -EFAULT; 355 356 *off = o + count; 357 filp->f_dentry->d_inode->i_atime = filp->f_dentry->d_inode->i_ctime = CURRENT_TIME; 358 return count; 359} 360 361static int mqueue_flush_file(struct file *filp, fl_owner_t id) 362{ 363 struct mqueue_inode_info *info = MQUEUE_I(filp->f_dentry->d_inode); 364 365 spin_lock(&info->lock); 366 if (current->tgid == info->notify_owner) 367 remove_notification(info); 368 369 spin_unlock(&info->lock); 370 return 0; 371} 372 373static unsigned int mqueue_poll_file(struct file *filp, struct poll_table_struct *poll_tab) 374{ 375 struct mqueue_inode_info *info = MQUEUE_I(filp->f_dentry->d_inode); 376 int retval = 0; 377 378 poll_wait(filp, &info->wait_q, poll_tab); 379 380 spin_lock(&info->lock); 381 if (info->attr.mq_curmsgs) 382 retval = POLLIN | POLLRDNORM; 383 384 if (info->attr.mq_curmsgs < info->attr.mq_maxmsg) 385 retval |= POLLOUT | POLLWRNORM; 386 spin_unlock(&info->lock); 387 388 return retval; 389} 390 391/* Adds current to info->e_wait_q[sr] before element with smaller prio */ 392static void wq_add(struct mqueue_inode_info *info, int sr, 393 struct ext_wait_queue *ewp) 394{ 395 struct ext_wait_queue *walk; 396 397 ewp->task = current; 398 399 list_for_each_entry(walk, &info->e_wait_q[sr].list, list) { 400 if (walk->task->static_prio <= current->static_prio) { 401 list_add_tail(&ewp->list, &walk->list); 402 return; 403 } 404 } 405 list_add_tail(&ewp->list, &info->e_wait_q[sr].list); 406} 407 408/* 409 * Puts current task to sleep. Caller must hold queue lock. After return 410 * lock isn't held. 411 * sr: SEND or RECV 412 */ 413static int wq_sleep(struct mqueue_inode_info *info, int sr, 414 long timeout, struct ext_wait_queue *ewp) 415{ 416 int retval; 417 signed long time; 418 419 wq_add(info, sr, ewp); 420 421 for (;;) { 422 set_current_state(TASK_INTERRUPTIBLE); 423 424 spin_unlock(&info->lock); 425 time = schedule_timeout(timeout); 426 427 while (ewp->state == STATE_PENDING) 428 cpu_relax(); 429 430 if (ewp->state == STATE_READY) { 431 retval = 0; 432 goto out; 433 } 434 spin_lock(&info->lock); 435 if (ewp->state == STATE_READY) { 436 retval = 0; 437 goto out_unlock; 438 } 439 if (signal_pending(current)) { 440 retval = -ERESTARTSYS; 441 break; 442 } 443 if (time == 0) { 444 retval = -ETIMEDOUT; 445 break; 446 } 447 } 448 list_del(&ewp->list); 449out_unlock: 450 spin_unlock(&info->lock); 451out: 452 return retval; 453} 454 455/* 456 * Returns waiting task that should be serviced first or NULL if none exists 457 */ 458static struct ext_wait_queue *wq_get_first_waiter( 459 struct mqueue_inode_info *info, int sr) 460{ 461 struct list_head *ptr; 462 463 ptr = info->e_wait_q[sr].list.prev; 464 if (ptr == &info->e_wait_q[sr].list) 465 return NULL; 466 return list_entry(ptr, struct ext_wait_queue, list); 467} 468 469/* Auxiliary functions to manipulate messages' list */ 470static void msg_insert(struct msg_msg *ptr, struct mqueue_inode_info *info) 471{ 472 int k; 473 474 k = info->attr.mq_curmsgs - 1; 475 while (k >= 0 && info->messages[k]->m_type >= ptr->m_type) { 476 info->messages[k + 1] = info->messages[k]; 477 k--; 478 } 479 info->attr.mq_curmsgs++; 480 info->qsize += ptr->m_ts; 481 info->messages[k + 1] = ptr; 482} 483 484static inline struct msg_msg *msg_get(struct mqueue_inode_info *info) 485{ 486 info->qsize -= info->messages[--info->attr.mq_curmsgs]->m_ts; 487 return info->messages[info->attr.mq_curmsgs]; 488} 489 490static inline void set_cookie(struct sk_buff *skb, char code) 491{ 492 ((char*)skb->data)[NOTIFY_COOKIE_LEN-1] = code; 493} 494 495/* 496 * The next function is only to split too long sys_mq_timedsend 497 */ 498static void __do_notify(struct mqueue_inode_info *info) 499{ 500 /* notification 501 * invoked when there is registered process and there isn't process 502 * waiting synchronously for message AND state of queue changed from 503 * empty to not empty. Here we are sure that no one is waiting 504 * synchronously. */ 505 if (info->notify_owner && 506 info->attr.mq_curmsgs == 1) { 507 struct siginfo sig_i; 508 switch (info->notify.sigev_notify) { 509 case SIGEV_NONE: 510 break; 511 case SIGEV_SIGNAL: 512 /* sends signal */ 513 514 sig_i.si_signo = info->notify.sigev_signo; 515 sig_i.si_errno = 0; 516 sig_i.si_code = SI_MESGQ; 517 sig_i.si_value = info->notify.sigev_value; 518 sig_i.si_pid = current->tgid; 519 sig_i.si_uid = current->uid; 520 521 kill_proc_info(info->notify.sigev_signo, 522 &sig_i, info->notify_owner); 523 break; 524 case SIGEV_THREAD: 525 set_cookie(info->notify_cookie, NOTIFY_WOKENUP); 526 netlink_sendskb(info->notify_sock, 527 info->notify_cookie, 0); 528 break; 529 } 530 /* after notification unregisters process */ 531 info->notify_owner = 0; 532 } 533 wake_up(&info->wait_q); 534} 535 536static long prepare_timeout(const struct timespec __user *u_arg) 537{ 538 struct timespec ts, nowts; 539 long timeout; 540 541 if (u_arg) { 542 if (unlikely(copy_from_user(&ts, u_arg, 543 sizeof(struct timespec)))) 544 return -EFAULT; 545 546 if (unlikely(ts.tv_nsec < 0 || ts.tv_sec < 0 547 || ts.tv_nsec >= NSEC_PER_SEC)) 548 return -EINVAL; 549 nowts = CURRENT_TIME; 550 /* first subtract as jiffies can't be too big */ 551 ts.tv_sec -= nowts.tv_sec; 552 if (ts.tv_nsec < nowts.tv_nsec) { 553 ts.tv_nsec += NSEC_PER_SEC; 554 ts.tv_sec--; 555 } 556 ts.tv_nsec -= nowts.tv_nsec; 557 if (ts.tv_sec < 0) 558 return 0; 559 560 timeout = timespec_to_jiffies(&ts) + 1; 561 } else 562 return MAX_SCHEDULE_TIMEOUT; 563 564 return timeout; 565} 566 567static void remove_notification(struct mqueue_inode_info *info) 568{ 569 if (info->notify_owner != 0 && 570 info->notify.sigev_notify == SIGEV_THREAD) { 571 set_cookie(info->notify_cookie, NOTIFY_REMOVED); 572 netlink_sendskb(info->notify_sock, info->notify_cookie, 0); 573 } 574 info->notify_owner = 0; 575} 576 577static int mq_attr_ok(struct mq_attr *attr) 578{ 579 if (attr->mq_maxmsg <= 0 || attr->mq_msgsize <= 0) 580 return 0; 581 if (capable(CAP_SYS_RESOURCE)) { 582 if (attr->mq_maxmsg > HARD_MSGMAX) 583 return 0; 584 } else { 585 if (attr->mq_maxmsg > msg_max || 586 attr->mq_msgsize > msgsize_max) 587 return 0; 588 } 589 /* check for overflow */ 590 if (attr->mq_msgsize > ULONG_MAX/attr->mq_maxmsg) 591 return 0; 592 if ((unsigned long)(attr->mq_maxmsg * attr->mq_msgsize) + 593 (attr->mq_maxmsg * sizeof (struct msg_msg *)) < 594 (unsigned long)(attr->mq_maxmsg * attr->mq_msgsize)) 595 return 0; 596 return 1; 597} 598 599/* 600 * Invoked when creating a new queue via sys_mq_open 601 */ 602static struct file *do_create(struct dentry *dir, struct dentry *dentry, 603 int oflag, mode_t mode, struct mq_attr __user *u_attr) 604{ 605 struct mq_attr attr; 606 int ret; 607 608 if (u_attr) { 609 ret = -EFAULT; 610 if (copy_from_user(&attr, u_attr, sizeof(attr))) 611 goto out; 612 ret = -EINVAL; 613 if (!mq_attr_ok(&attr)) 614 goto out; 615 /* store for use during create */ 616 dentry->d_fsdata = &attr; 617 } 618 619 mode &= ~current->fs->umask; 620 ret = vfs_create(dir->d_inode, dentry, mode, NULL); 621 dentry->d_fsdata = NULL; 622 if (ret) 623 goto out; 624 625 return dentry_open(dentry, mqueue_mnt, oflag); 626 627out: 628 dput(dentry); 629 mntput(mqueue_mnt); 630 return ERR_PTR(ret); 631} 632 633/* Opens existing queue */ 634static struct file *do_open(struct dentry *dentry, int oflag) 635{ 636static int oflag2acc[O_ACCMODE] = { MAY_READ, MAY_WRITE, 637 MAY_READ | MAY_WRITE }; 638 639 if ((oflag & O_ACCMODE) == (O_RDWR | O_WRONLY)) { 640 dput(dentry); 641 mntput(mqueue_mnt); 642 return ERR_PTR(-EINVAL); 643 } 644 645 if (permission(dentry->d_inode, oflag2acc[oflag & O_ACCMODE], NULL)) { 646 dput(dentry); 647 mntput(mqueue_mnt); 648 return ERR_PTR(-EACCES); 649 } 650 651 return dentry_open(dentry, mqueue_mnt, oflag); 652} 653 654asmlinkage long sys_mq_open(const char __user *u_name, int oflag, mode_t mode, 655 struct mq_attr __user *u_attr) 656{ 657 struct dentry *dentry; 658 struct file *filp; 659 char *name; 660 int fd, error; 661 662 error = audit_mq_open(oflag, mode, u_attr); 663 if (error != 0) 664 return error; 665 666 if (IS_ERR(name = getname(u_name))) 667 return PTR_ERR(name); 668 669 fd = get_unused_fd(); 670 if (fd < 0) 671 goto out_putname; 672 673 mutex_lock(&mqueue_mnt->mnt_root->d_inode->i_mutex); 674 dentry = lookup_one_len(name, mqueue_mnt->mnt_root, strlen(name)); 675 if (IS_ERR(dentry)) { 676 error = PTR_ERR(dentry); 677 goto out_err; 678 } 679 mntget(mqueue_mnt); 680 681 if (oflag & O_CREAT) { 682 if (dentry->d_inode) { /* entry already exists */ 683 error = -EEXIST; 684 if (oflag & O_EXCL) 685 goto out; 686 filp = do_open(dentry, oflag); 687 } else { 688 filp = do_create(mqueue_mnt->mnt_root, dentry, 689 oflag, mode, u_attr); 690 } 691 } else { 692 error = -ENOENT; 693 if (!dentry->d_inode) 694 goto out; 695 filp = do_open(dentry, oflag); 696 } 697 698 if (IS_ERR(filp)) { 699 error = PTR_ERR(filp); 700 goto out_putfd; 701 } 702 703 set_close_on_exec(fd, 1); 704 fd_install(fd, filp); 705 goto out_upsem; 706 707out: 708 dput(dentry); 709 mntput(mqueue_mnt); 710out_putfd: 711 put_unused_fd(fd); 712out_err: 713 fd = error; 714out_upsem: 715 mutex_unlock(&mqueue_mnt->mnt_root->d_inode->i_mutex); 716out_putname: 717 putname(name); 718 return fd; 719} 720 721asmlinkage long sys_mq_unlink(const char __user *u_name) 722{ 723 int err; 724 char *name; 725 struct dentry *dentry; 726 struct inode *inode = NULL; 727 728 name = getname(u_name); 729 if (IS_ERR(name)) 730 return PTR_ERR(name); 731 732 mutex_lock(&mqueue_mnt->mnt_root->d_inode->i_mutex); 733 dentry = lookup_one_len(name, mqueue_mnt->mnt_root, strlen(name)); 734 if (IS_ERR(dentry)) { 735 err = PTR_ERR(dentry); 736 goto out_unlock; 737 } 738 739 if (!dentry->d_inode) { 740 err = -ENOENT; 741 goto out_err; 742 } 743 744 inode = dentry->d_inode; 745 if (inode) 746 atomic_inc(&inode->i_count); 747 748 err = vfs_unlink(dentry->d_parent->d_inode, dentry); 749out_err: 750 dput(dentry); 751 752out_unlock: 753 mutex_unlock(&mqueue_mnt->mnt_root->d_inode->i_mutex); 754 putname(name); 755 if (inode) 756 iput(inode); 757 758 return err; 759} 760 761/* Pipelined send and receive functions. 762 * 763 * If a receiver finds no waiting message, then it registers itself in the 764 * list of waiting receivers. A sender checks that list before adding the new 765 * message into the message array. If there is a waiting receiver, then it 766 * bypasses the message array and directly hands the message over to the 767 * receiver. 768 * The receiver accepts the message and returns without grabbing the queue 769 * spinlock. Therefore an intermediate STATE_PENDING state and memory barriers 770 * are necessary. The same algorithm is used for sysv semaphores, see 771 * ipc/sem.c for more details. 772 * 773 * The same algorithm is used for senders. 774 */ 775 776/* pipelined_send() - send a message directly to the task waiting in 777 * sys_mq_timedreceive() (without inserting message into a queue). 778 */ 779static inline void pipelined_send(struct mqueue_inode_info *info, 780 struct msg_msg *message, 781 struct ext_wait_queue *receiver) 782{ 783 receiver->msg = message; 784 list_del(&receiver->list); 785 receiver->state = STATE_PENDING; 786 wake_up_process(receiver->task); 787 smp_wmb(); 788 receiver->state = STATE_READY; 789} 790 791/* pipelined_receive() - if there is task waiting in sys_mq_timedsend() 792 * gets its message and put to the queue (we have one free place for sure). */ 793static inline void pipelined_receive(struct mqueue_inode_info *info) 794{ 795 struct ext_wait_queue *sender = wq_get_first_waiter(info, SEND); 796 797 if (!sender) { 798 /* for poll */ 799 wake_up_interruptible(&info->wait_q); 800 return; 801 } 802 msg_insert(sender->msg, info); 803 list_del(&sender->list); 804 sender->state = STATE_PENDING; 805 wake_up_process(sender->task); 806 smp_wmb(); 807 sender->state = STATE_READY; 808} 809 810asmlinkage long sys_mq_timedsend(mqd_t mqdes, const char __user *u_msg_ptr, 811 size_t msg_len, unsigned int msg_prio, 812 const struct timespec __user *u_abs_timeout) 813{ 814 struct file *filp; 815 struct inode *inode; 816 struct ext_wait_queue wait; 817 struct ext_wait_queue *receiver; 818 struct msg_msg *msg_ptr; 819 struct mqueue_inode_info *info; 820 long timeout; 821 int ret; 822 823 ret = audit_mq_timedsend(mqdes, msg_len, msg_prio, u_abs_timeout); 824 if (ret != 0) 825 return ret; 826 827 if (unlikely(msg_prio >= (unsigned long) MQ_PRIO_MAX)) 828 return -EINVAL; 829 830 timeout = prepare_timeout(u_abs_timeout); 831 832 ret = -EBADF; 833 filp = fget(mqdes); 834 if (unlikely(!filp)) 835 goto out; 836 837 inode = filp->f_dentry->d_inode; 838 if (unlikely(filp->f_op != &mqueue_file_operations)) 839 goto out_fput; 840 info = MQUEUE_I(inode); 841 842 if (unlikely(!(filp->f_mode & FMODE_WRITE))) 843 goto out_fput; 844 845 if (unlikely(msg_len > info->attr.mq_msgsize)) { 846 ret = -EMSGSIZE; 847 goto out_fput; 848 } 849 850 /* First try to allocate memory, before doing anything with 851 * existing queues. */ 852 msg_ptr = load_msg(u_msg_ptr, msg_len); 853 if (IS_ERR(msg_ptr)) { 854 ret = PTR_ERR(msg_ptr); 855 goto out_fput; 856 } 857 msg_ptr->m_ts = msg_len; 858 msg_ptr->m_type = msg_prio; 859 860 spin_lock(&info->lock); 861 862 if (info->attr.mq_curmsgs == info->attr.mq_maxmsg) { 863 if (filp->f_flags & O_NONBLOCK) { 864 spin_unlock(&info->lock); 865 ret = -EAGAIN; 866 } else if (unlikely(timeout < 0)) { 867 spin_unlock(&info->lock); 868 ret = timeout; 869 } else { 870 wait.task = current; 871 wait.msg = (void *) msg_ptr; 872 wait.state = STATE_NONE; 873 ret = wq_sleep(info, SEND, timeout, &wait); 874 } 875 if (ret < 0) 876 free_msg(msg_ptr); 877 } else { 878 receiver = wq_get_first_waiter(info, RECV); 879 if (receiver) { 880 pipelined_send(info, msg_ptr, receiver); 881 } else { 882 /* adds message to the queue */ 883 msg_insert(msg_ptr, info); 884 __do_notify(info); 885 } 886 inode->i_atime = inode->i_mtime = inode->i_ctime = 887 CURRENT_TIME; 888 spin_unlock(&info->lock); 889 ret = 0; 890 } 891out_fput: 892 fput(filp); 893out: 894 return ret; 895} 896 897asmlinkage ssize_t sys_mq_timedreceive(mqd_t mqdes, char __user *u_msg_ptr, 898 size_t msg_len, unsigned int __user *u_msg_prio, 899 const struct timespec __user *u_abs_timeout) 900{ 901 long timeout; 902 ssize_t ret; 903 struct msg_msg *msg_ptr; 904 struct file *filp; 905 struct inode *inode; 906 struct mqueue_inode_info *info; 907 struct ext_wait_queue wait; 908 909 ret = audit_mq_timedreceive(mqdes, msg_len, u_msg_prio, u_abs_timeout); 910 if (ret != 0) 911 return ret; 912 913 timeout = prepare_timeout(u_abs_timeout); 914 915 ret = -EBADF; 916 filp = fget(mqdes); 917 if (unlikely(!filp)) 918 goto out; 919 920 inode = filp->f_dentry->d_inode; 921 if (unlikely(filp->f_op != &mqueue_file_operations)) 922 goto out_fput; 923 info = MQUEUE_I(inode); 924 925 if (unlikely(!(filp->f_mode & FMODE_READ))) 926 goto out_fput; 927 928 /* checks if buffer is big enough */ 929 if (unlikely(msg_len < info->attr.mq_msgsize)) { 930 ret = -EMSGSIZE; 931 goto out_fput; 932 } 933 934 spin_lock(&info->lock); 935 if (info->attr.mq_curmsgs == 0) { 936 if (filp->f_flags & O_NONBLOCK) { 937 spin_unlock(&info->lock); 938 ret = -EAGAIN; 939 msg_ptr = NULL; 940 } else if (unlikely(timeout < 0)) { 941 spin_unlock(&info->lock); 942 ret = timeout; 943 msg_ptr = NULL; 944 } else { 945 wait.task = current; 946 wait.state = STATE_NONE; 947 ret = wq_sleep(info, RECV, timeout, &wait); 948 msg_ptr = wait.msg; 949 } 950 } else { 951 msg_ptr = msg_get(info); 952 953 inode->i_atime = inode->i_mtime = inode->i_ctime = 954 CURRENT_TIME; 955 956 /* There is now free space in queue. */ 957 pipelined_receive(info); 958 spin_unlock(&info->lock); 959 ret = 0; 960 } 961 if (ret == 0) { 962 ret = msg_ptr->m_ts; 963 964 if ((u_msg_prio && put_user(msg_ptr->m_type, u_msg_prio)) || 965 store_msg(u_msg_ptr, msg_ptr, msg_ptr->m_ts)) { 966 ret = -EFAULT; 967 } 968 free_msg(msg_ptr); 969 } 970out_fput: 971 fput(filp); 972out: 973 return ret; 974} 975 976/* 977 * Notes: the case when user wants us to deregister (with NULL as pointer) 978 * and he isn't currently owner of notification, will be silently discarded. 979 * It isn't explicitly defined in the POSIX. 980 */ 981asmlinkage long sys_mq_notify(mqd_t mqdes, 982 const struct sigevent __user *u_notification) 983{ 984 int ret; 985 struct file *filp; 986 struct sock *sock; 987 struct inode *inode; 988 struct sigevent notification; 989 struct mqueue_inode_info *info; 990 struct sk_buff *nc; 991 992 ret = audit_mq_notify(mqdes, u_notification); 993 if (ret != 0) 994 return ret; 995 996 nc = NULL; 997 sock = NULL; 998 if (u_notification != NULL) { 999 if (copy_from_user(¬ification, u_notification, 1000 sizeof(struct sigevent))) 1001 return -EFAULT; 1002 1003 if (unlikely(notification.sigev_notify != SIGEV_NONE && 1004 notification.sigev_notify != SIGEV_SIGNAL && 1005 notification.sigev_notify != SIGEV_THREAD)) 1006 return -EINVAL; 1007 if (notification.sigev_notify == SIGEV_SIGNAL && 1008 !valid_signal(notification.sigev_signo)) { 1009 return -EINVAL; 1010 } 1011 if (notification.sigev_notify == SIGEV_THREAD) { 1012 /* create the notify skb */ 1013 nc = alloc_skb(NOTIFY_COOKIE_LEN, GFP_KERNEL); 1014 ret = -ENOMEM; 1015 if (!nc) 1016 goto out; 1017 ret = -EFAULT; 1018 if (copy_from_user(nc->data, 1019 notification.sigev_value.sival_ptr, 1020 NOTIFY_COOKIE_LEN)) { 1021 goto out; 1022 } 1023 1024 /* TODO: add a header? */ 1025 skb_put(nc, NOTIFY_COOKIE_LEN); 1026 /* and attach it to the socket */ 1027retry: 1028 filp = fget(notification.sigev_signo); 1029 ret = -EBADF; 1030 if (!filp) 1031 goto out; 1032 sock = netlink_getsockbyfilp(filp); 1033 fput(filp); 1034 if (IS_ERR(sock)) { 1035 ret = PTR_ERR(sock); 1036 sock = NULL; 1037 goto out; 1038 } 1039 1040 ret = netlink_attachskb(sock, nc, 0, 1041 MAX_SCHEDULE_TIMEOUT, NULL); 1042 if (ret == 1) 1043 goto retry; 1044 if (ret) { 1045 sock = NULL; 1046 nc = NULL; 1047 goto out; 1048 } 1049 } 1050 } 1051 1052 ret = -EBADF; 1053 filp = fget(mqdes); 1054 if (!filp) 1055 goto out; 1056 1057 inode = filp->f_dentry->d_inode; 1058 if (unlikely(filp->f_op != &mqueue_file_operations)) 1059 goto out_fput; 1060 info = MQUEUE_I(inode); 1061 1062 ret = 0; 1063 spin_lock(&info->lock); 1064 if (u_notification == NULL) { 1065 if (info->notify_owner == current->tgid) { 1066 remove_notification(info); 1067 inode->i_atime = inode->i_ctime = CURRENT_TIME; 1068 } 1069 } else if (info->notify_owner != 0) { 1070 ret = -EBUSY; 1071 } else { 1072 switch (notification.sigev_notify) { 1073 case SIGEV_NONE: 1074 info->notify.sigev_notify = SIGEV_NONE; 1075 break; 1076 case SIGEV_THREAD: 1077 info->notify_sock = sock; 1078 info->notify_cookie = nc; 1079 sock = NULL; 1080 nc = NULL; 1081 info->notify.sigev_notify = SIGEV_THREAD; 1082 break; 1083 case SIGEV_SIGNAL: 1084 info->notify.sigev_signo = notification.sigev_signo; 1085 info->notify.sigev_value = notification.sigev_value; 1086 info->notify.sigev_notify = SIGEV_SIGNAL; 1087 break; 1088 } 1089 info->notify_owner = current->tgid; 1090 inode->i_atime = inode->i_ctime = CURRENT_TIME; 1091 } 1092 spin_unlock(&info->lock); 1093out_fput: 1094 fput(filp); 1095out: 1096 if (sock) { 1097 netlink_detachskb(sock, nc); 1098 } else if (nc) { 1099 dev_kfree_skb(nc); 1100 } 1101 return ret; 1102} 1103 1104asmlinkage long sys_mq_getsetattr(mqd_t mqdes, 1105 const struct mq_attr __user *u_mqstat, 1106 struct mq_attr __user *u_omqstat) 1107{ 1108 int ret; 1109 struct mq_attr mqstat, omqstat; 1110 struct file *filp; 1111 struct inode *inode; 1112 struct mqueue_inode_info *info; 1113 1114 if (u_mqstat != NULL) { 1115 if (copy_from_user(&mqstat, u_mqstat, sizeof(struct mq_attr))) 1116 return -EFAULT; 1117 if (mqstat.mq_flags & (~O_NONBLOCK)) 1118 return -EINVAL; 1119 } 1120 1121 ret = -EBADF; 1122 filp = fget(mqdes); 1123 if (!filp) 1124 goto out; 1125 1126 inode = filp->f_dentry->d_inode; 1127 if (unlikely(filp->f_op != &mqueue_file_operations)) 1128 goto out_fput; 1129 info = MQUEUE_I(inode); 1130 1131 spin_lock(&info->lock); 1132 1133 omqstat = info->attr; 1134 omqstat.mq_flags = filp->f_flags & O_NONBLOCK; 1135 if (u_mqstat) { 1136 ret = audit_mq_getsetattr(mqdes, &mqstat); 1137 if (ret != 0) 1138 goto out; 1139 if (mqstat.mq_flags & O_NONBLOCK) 1140 filp->f_flags |= O_NONBLOCK; 1141 else 1142 filp->f_flags &= ~O_NONBLOCK; 1143 1144 inode->i_atime = inode->i_ctime = CURRENT_TIME; 1145 } 1146 1147 spin_unlock(&info->lock); 1148 1149 ret = 0; 1150 if (u_omqstat != NULL && copy_to_user(u_omqstat, &omqstat, 1151 sizeof(struct mq_attr))) 1152 ret = -EFAULT; 1153 1154out_fput: 1155 fput(filp); 1156out: 1157 return ret; 1158} 1159 1160static struct inode_operations mqueue_dir_inode_operations = { 1161 .lookup = simple_lookup, 1162 .create = mqueue_create, 1163 .unlink = mqueue_unlink, 1164}; 1165 1166static struct file_operations mqueue_file_operations = { 1167 .flush = mqueue_flush_file, 1168 .poll = mqueue_poll_file, 1169 .read = mqueue_read_file, 1170}; 1171 1172static struct super_operations mqueue_super_ops = { 1173 .alloc_inode = mqueue_alloc_inode, 1174 .destroy_inode = mqueue_destroy_inode, 1175 .statfs = simple_statfs, 1176 .delete_inode = mqueue_delete_inode, 1177 .drop_inode = generic_delete_inode, 1178}; 1179 1180static struct file_system_type mqueue_fs_type = { 1181 .name = "mqueue", 1182 .get_sb = mqueue_get_sb, 1183 .kill_sb = kill_litter_super, 1184}; 1185 1186static int msg_max_limit_min = DFLT_MSGMAX; 1187static int msg_max_limit_max = HARD_MSGMAX; 1188 1189static int msg_maxsize_limit_min = DFLT_MSGSIZEMAX; 1190static int msg_maxsize_limit_max = INT_MAX; 1191 1192static ctl_table mq_sysctls[] = { 1193 { 1194 .ctl_name = CTL_QUEUESMAX, 1195 .procname = "queues_max", 1196 .data = &queues_max, 1197 .maxlen = sizeof(int), 1198 .mode = 0644, 1199 .proc_handler = &proc_dointvec, 1200 }, 1201 { 1202 .ctl_name = CTL_MSGMAX, 1203 .procname = "msg_max", 1204 .data = &msg_max, 1205 .maxlen = sizeof(int), 1206 .mode = 0644, 1207 .proc_handler = &proc_dointvec_minmax, 1208 .extra1 = &msg_max_limit_min, 1209 .extra2 = &msg_max_limit_max, 1210 }, 1211 { 1212 .ctl_name = CTL_MSGSIZEMAX, 1213 .procname = "msgsize_max", 1214 .data = &msgsize_max, 1215 .maxlen = sizeof(int), 1216 .mode = 0644, 1217 .proc_handler = &proc_dointvec_minmax, 1218 .extra1 = &msg_maxsize_limit_min, 1219 .extra2 = &msg_maxsize_limit_max, 1220 }, 1221 { .ctl_name = 0 } 1222}; 1223 1224static ctl_table mq_sysctl_dir[] = { 1225 { 1226 .ctl_name = FS_MQUEUE, 1227 .procname = "mqueue", 1228 .mode = 0555, 1229 .child = mq_sysctls, 1230 }, 1231 { .ctl_name = 0 } 1232}; 1233 1234static ctl_table mq_sysctl_root[] = { 1235 { 1236 .ctl_name = CTL_FS, 1237 .procname = "fs", 1238 .mode = 0555, 1239 .child = mq_sysctl_dir, 1240 }, 1241 { .ctl_name = 0 } 1242}; 1243 1244static int __init init_mqueue_fs(void) 1245{ 1246 int error; 1247 1248 mqueue_inode_cachep = kmem_cache_create("mqueue_inode_cache", 1249 sizeof(struct mqueue_inode_info), 0, 1250 SLAB_HWCACHE_ALIGN, init_once, NULL); 1251 if (mqueue_inode_cachep == NULL) 1252 return -ENOMEM; 1253 1254 /* ignore failues - they are not fatal */ 1255 mq_sysctl_table = register_sysctl_table(mq_sysctl_root, 0); 1256 1257 error = register_filesystem(&mqueue_fs_type); 1258 if (error) 1259 goto out_sysctl; 1260 1261 if (IS_ERR(mqueue_mnt = kern_mount(&mqueue_fs_type))) { 1262 error = PTR_ERR(mqueue_mnt); 1263 goto out_filesystem; 1264 } 1265 1266 /* internal initialization - not common for vfs */ 1267 queues_count = 0; 1268 spin_lock_init(&mq_lock); 1269 1270 return 0; 1271 1272out_filesystem: 1273 unregister_filesystem(&mqueue_fs_type); 1274out_sysctl: 1275 if (mq_sysctl_table) 1276 unregister_sysctl_table(mq_sysctl_table); 1277 kmem_cache_destroy(mqueue_inode_cachep); 1278 return error; 1279} 1280 1281__initcall(init_mqueue_fs); 1282