mqueue.c revision b6dff3ec5e116e3af6f537d4caedcad6b9e5082a
1/* 2 * POSIX message queues filesystem for Linux. 3 * 4 * Copyright (C) 2003,2004 Krzysztof Benedyczak (golbi@mat.uni.torun.pl) 5 * Michal Wronski (michal.wronski@gmail.com) 6 * 7 * Spinlocks: Mohamed Abbas (abbas.mohamed@intel.com) 8 * Lockless receive & send, fd based notify: 9 * Manfred Spraul (manfred@colorfullife.com) 10 * 11 * Audit: George Wilson (ltcgcw@us.ibm.com) 12 * 13 * This file is released under the GPL. 14 */ 15 16#include <linux/capability.h> 17#include <linux/init.h> 18#include <linux/pagemap.h> 19#include <linux/file.h> 20#include <linux/mount.h> 21#include <linux/namei.h> 22#include <linux/sysctl.h> 23#include <linux/poll.h> 24#include <linux/mqueue.h> 25#include <linux/msg.h> 26#include <linux/skbuff.h> 27#include <linux/netlink.h> 28#include <linux/syscalls.h> 29#include <linux/audit.h> 30#include <linux/signal.h> 31#include <linux/mutex.h> 32#include <linux/nsproxy.h> 33#include <linux/pid.h> 34 35#include <net/sock.h> 36#include "util.h" 37 38#define MQUEUE_MAGIC 0x19800202 39#define DIRENT_SIZE 20 40#define FILENT_SIZE 80 41 42#define SEND 0 43#define RECV 1 44 45#define STATE_NONE 0 46#define STATE_PENDING 1 47#define STATE_READY 2 48 49/* default values */ 50#define DFLT_QUEUESMAX 256 /* max number of message queues */ 51#define DFLT_MSGMAX 10 /* max number of messages in each queue */ 52#define HARD_MSGMAX (131072/sizeof(void*)) 53#define DFLT_MSGSIZEMAX 8192 /* max message size */ 54 55/* 56 * Define the ranges various user-specified maximum values can 57 * be set to. 58 */ 59#define MIN_MSGMAX 1 /* min value for msg_max */ 60#define MAX_MSGMAX HARD_MSGMAX /* max value for msg_max */ 61#define MIN_MSGSIZEMAX 128 /* min value for msgsize_max */ 62#define MAX_MSGSIZEMAX (8192*128) /* max value for msgsize_max */ 63 64struct ext_wait_queue { /* queue of sleeping tasks */ 65 struct task_struct *task; 66 struct list_head list; 67 struct msg_msg *msg; /* ptr of loaded message */ 68 int state; /* one of STATE_* values */ 69}; 70 71struct mqueue_inode_info { 72 spinlock_t lock; 73 struct inode vfs_inode; 74 wait_queue_head_t wait_q; 75 76 struct msg_msg **messages; 77 struct mq_attr attr; 78 79 struct sigevent notify; 80 struct pid* notify_owner; 81 struct user_struct *user; /* user who created, for accounting */ 82 struct sock *notify_sock; 83 struct sk_buff *notify_cookie; 84 85 /* for tasks waiting for free space and messages, respectively */ 86 struct ext_wait_queue e_wait_q[2]; 87 88 unsigned long qsize; /* size of queue in memory (sum of all msgs) */ 89}; 90 91static const struct inode_operations mqueue_dir_inode_operations; 92static const struct file_operations mqueue_file_operations; 93static struct super_operations mqueue_super_ops; 94static void remove_notification(struct mqueue_inode_info *info); 95 96static spinlock_t mq_lock; 97static struct kmem_cache *mqueue_inode_cachep; 98static struct vfsmount *mqueue_mnt; 99 100static unsigned int queues_count; 101static unsigned int queues_max = DFLT_QUEUESMAX; 102static unsigned int msg_max = DFLT_MSGMAX; 103static unsigned int msgsize_max = DFLT_MSGSIZEMAX; 104 105static struct ctl_table_header * mq_sysctl_table; 106 107static inline struct mqueue_inode_info *MQUEUE_I(struct inode *inode) 108{ 109 return container_of(inode, struct mqueue_inode_info, vfs_inode); 110} 111 112static struct inode *mqueue_get_inode(struct super_block *sb, int mode, 113 struct mq_attr *attr) 114{ 115 struct inode *inode; 116 117 inode = new_inode(sb); 118 if (inode) { 119 inode->i_mode = mode; 120 inode->i_uid = current_fsuid(); 121 inode->i_gid = current_fsgid(); 122 inode->i_blocks = 0; 123 inode->i_mtime = inode->i_ctime = inode->i_atime = 124 CURRENT_TIME; 125 126 if (S_ISREG(mode)) { 127 struct mqueue_inode_info *info; 128 struct task_struct *p = current; 129 struct user_struct *u = p->cred->user; 130 unsigned long mq_bytes, mq_msg_tblsz; 131 132 inode->i_fop = &mqueue_file_operations; 133 inode->i_size = FILENT_SIZE; 134 /* mqueue specific info */ 135 info = MQUEUE_I(inode); 136 spin_lock_init(&info->lock); 137 init_waitqueue_head(&info->wait_q); 138 INIT_LIST_HEAD(&info->e_wait_q[0].list); 139 INIT_LIST_HEAD(&info->e_wait_q[1].list); 140 info->messages = NULL; 141 info->notify_owner = NULL; 142 info->qsize = 0; 143 info->user = NULL; /* set when all is ok */ 144 memset(&info->attr, 0, sizeof(info->attr)); 145 info->attr.mq_maxmsg = msg_max; 146 info->attr.mq_msgsize = msgsize_max; 147 if (attr) { 148 info->attr.mq_maxmsg = attr->mq_maxmsg; 149 info->attr.mq_msgsize = attr->mq_msgsize; 150 } 151 mq_msg_tblsz = info->attr.mq_maxmsg * sizeof(struct msg_msg *); 152 mq_bytes = (mq_msg_tblsz + 153 (info->attr.mq_maxmsg * info->attr.mq_msgsize)); 154 155 spin_lock(&mq_lock); 156 if (u->mq_bytes + mq_bytes < u->mq_bytes || 157 u->mq_bytes + mq_bytes > 158 p->signal->rlim[RLIMIT_MSGQUEUE].rlim_cur) { 159 spin_unlock(&mq_lock); 160 goto out_inode; 161 } 162 u->mq_bytes += mq_bytes; 163 spin_unlock(&mq_lock); 164 165 info->messages = kmalloc(mq_msg_tblsz, GFP_KERNEL); 166 if (!info->messages) { 167 spin_lock(&mq_lock); 168 u->mq_bytes -= mq_bytes; 169 spin_unlock(&mq_lock); 170 goto out_inode; 171 } 172 /* all is ok */ 173 info->user = get_uid(u); 174 } else if (S_ISDIR(mode)) { 175 inc_nlink(inode); 176 /* Some things misbehave if size == 0 on a directory */ 177 inode->i_size = 2 * DIRENT_SIZE; 178 inode->i_op = &mqueue_dir_inode_operations; 179 inode->i_fop = &simple_dir_operations; 180 } 181 } 182 return inode; 183out_inode: 184 make_bad_inode(inode); 185 iput(inode); 186 return NULL; 187} 188 189static int mqueue_fill_super(struct super_block *sb, void *data, int silent) 190{ 191 struct inode *inode; 192 193 sb->s_blocksize = PAGE_CACHE_SIZE; 194 sb->s_blocksize_bits = PAGE_CACHE_SHIFT; 195 sb->s_magic = MQUEUE_MAGIC; 196 sb->s_op = &mqueue_super_ops; 197 198 inode = mqueue_get_inode(sb, S_IFDIR | S_ISVTX | S_IRWXUGO, NULL); 199 if (!inode) 200 return -ENOMEM; 201 202 sb->s_root = d_alloc_root(inode); 203 if (!sb->s_root) { 204 iput(inode); 205 return -ENOMEM; 206 } 207 208 return 0; 209} 210 211static int mqueue_get_sb(struct file_system_type *fs_type, 212 int flags, const char *dev_name, 213 void *data, struct vfsmount *mnt) 214{ 215 return get_sb_single(fs_type, flags, data, mqueue_fill_super, mnt); 216} 217 218static void init_once(void *foo) 219{ 220 struct mqueue_inode_info *p = (struct mqueue_inode_info *) foo; 221 222 inode_init_once(&p->vfs_inode); 223} 224 225static struct inode *mqueue_alloc_inode(struct super_block *sb) 226{ 227 struct mqueue_inode_info *ei; 228 229 ei = kmem_cache_alloc(mqueue_inode_cachep, GFP_KERNEL); 230 if (!ei) 231 return NULL; 232 return &ei->vfs_inode; 233} 234 235static void mqueue_destroy_inode(struct inode *inode) 236{ 237 kmem_cache_free(mqueue_inode_cachep, MQUEUE_I(inode)); 238} 239 240static void mqueue_delete_inode(struct inode *inode) 241{ 242 struct mqueue_inode_info *info; 243 struct user_struct *user; 244 unsigned long mq_bytes; 245 int i; 246 247 if (S_ISDIR(inode->i_mode)) { 248 clear_inode(inode); 249 return; 250 } 251 info = MQUEUE_I(inode); 252 spin_lock(&info->lock); 253 for (i = 0; i < info->attr.mq_curmsgs; i++) 254 free_msg(info->messages[i]); 255 kfree(info->messages); 256 spin_unlock(&info->lock); 257 258 clear_inode(inode); 259 260 mq_bytes = (info->attr.mq_maxmsg * sizeof(struct msg_msg *) + 261 (info->attr.mq_maxmsg * info->attr.mq_msgsize)); 262 user = info->user; 263 if (user) { 264 spin_lock(&mq_lock); 265 user->mq_bytes -= mq_bytes; 266 queues_count--; 267 spin_unlock(&mq_lock); 268 free_uid(user); 269 } 270} 271 272static int mqueue_create(struct inode *dir, struct dentry *dentry, 273 int mode, struct nameidata *nd) 274{ 275 struct inode *inode; 276 struct mq_attr *attr = dentry->d_fsdata; 277 int error; 278 279 spin_lock(&mq_lock); 280 if (queues_count >= queues_max && !capable(CAP_SYS_RESOURCE)) { 281 error = -ENOSPC; 282 goto out_lock; 283 } 284 queues_count++; 285 spin_unlock(&mq_lock); 286 287 inode = mqueue_get_inode(dir->i_sb, mode, attr); 288 if (!inode) { 289 error = -ENOMEM; 290 spin_lock(&mq_lock); 291 queues_count--; 292 goto out_lock; 293 } 294 295 dir->i_size += DIRENT_SIZE; 296 dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME; 297 298 d_instantiate(dentry, inode); 299 dget(dentry); 300 return 0; 301out_lock: 302 spin_unlock(&mq_lock); 303 return error; 304} 305 306static int mqueue_unlink(struct inode *dir, struct dentry *dentry) 307{ 308 struct inode *inode = dentry->d_inode; 309 310 dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME; 311 dir->i_size -= DIRENT_SIZE; 312 drop_nlink(inode); 313 dput(dentry); 314 return 0; 315} 316 317/* 318* This is routine for system read from queue file. 319* To avoid mess with doing here some sort of mq_receive we allow 320* to read only queue size & notification info (the only values 321* that are interesting from user point of view and aren't accessible 322* through std routines) 323*/ 324static ssize_t mqueue_read_file(struct file *filp, char __user *u_data, 325 size_t count, loff_t *off) 326{ 327 struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode); 328 char buffer[FILENT_SIZE]; 329 ssize_t ret; 330 331 spin_lock(&info->lock); 332 snprintf(buffer, sizeof(buffer), 333 "QSIZE:%-10lu NOTIFY:%-5d SIGNO:%-5d NOTIFY_PID:%-6d\n", 334 info->qsize, 335 info->notify_owner ? info->notify.sigev_notify : 0, 336 (info->notify_owner && 337 info->notify.sigev_notify == SIGEV_SIGNAL) ? 338 info->notify.sigev_signo : 0, 339 pid_vnr(info->notify_owner)); 340 spin_unlock(&info->lock); 341 buffer[sizeof(buffer)-1] = '\0'; 342 343 ret = simple_read_from_buffer(u_data, count, off, buffer, 344 strlen(buffer)); 345 if (ret <= 0) 346 return ret; 347 348 filp->f_path.dentry->d_inode->i_atime = filp->f_path.dentry->d_inode->i_ctime = CURRENT_TIME; 349 return ret; 350} 351 352static int mqueue_flush_file(struct file *filp, fl_owner_t id) 353{ 354 struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode); 355 356 spin_lock(&info->lock); 357 if (task_tgid(current) == info->notify_owner) 358 remove_notification(info); 359 360 spin_unlock(&info->lock); 361 return 0; 362} 363 364static unsigned int mqueue_poll_file(struct file *filp, struct poll_table_struct *poll_tab) 365{ 366 struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode); 367 int retval = 0; 368 369 poll_wait(filp, &info->wait_q, poll_tab); 370 371 spin_lock(&info->lock); 372 if (info->attr.mq_curmsgs) 373 retval = POLLIN | POLLRDNORM; 374 375 if (info->attr.mq_curmsgs < info->attr.mq_maxmsg) 376 retval |= POLLOUT | POLLWRNORM; 377 spin_unlock(&info->lock); 378 379 return retval; 380} 381 382/* Adds current to info->e_wait_q[sr] before element with smaller prio */ 383static void wq_add(struct mqueue_inode_info *info, int sr, 384 struct ext_wait_queue *ewp) 385{ 386 struct ext_wait_queue *walk; 387 388 ewp->task = current; 389 390 list_for_each_entry(walk, &info->e_wait_q[sr].list, list) { 391 if (walk->task->static_prio <= current->static_prio) { 392 list_add_tail(&ewp->list, &walk->list); 393 return; 394 } 395 } 396 list_add_tail(&ewp->list, &info->e_wait_q[sr].list); 397} 398 399/* 400 * Puts current task to sleep. Caller must hold queue lock. After return 401 * lock isn't held. 402 * sr: SEND or RECV 403 */ 404static int wq_sleep(struct mqueue_inode_info *info, int sr, 405 long timeout, struct ext_wait_queue *ewp) 406{ 407 int retval; 408 signed long time; 409 410 wq_add(info, sr, ewp); 411 412 for (;;) { 413 set_current_state(TASK_INTERRUPTIBLE); 414 415 spin_unlock(&info->lock); 416 time = schedule_timeout(timeout); 417 418 while (ewp->state == STATE_PENDING) 419 cpu_relax(); 420 421 if (ewp->state == STATE_READY) { 422 retval = 0; 423 goto out; 424 } 425 spin_lock(&info->lock); 426 if (ewp->state == STATE_READY) { 427 retval = 0; 428 goto out_unlock; 429 } 430 if (signal_pending(current)) { 431 retval = -ERESTARTSYS; 432 break; 433 } 434 if (time == 0) { 435 retval = -ETIMEDOUT; 436 break; 437 } 438 } 439 list_del(&ewp->list); 440out_unlock: 441 spin_unlock(&info->lock); 442out: 443 return retval; 444} 445 446/* 447 * Returns waiting task that should be serviced first or NULL if none exists 448 */ 449static struct ext_wait_queue *wq_get_first_waiter( 450 struct mqueue_inode_info *info, int sr) 451{ 452 struct list_head *ptr; 453 454 ptr = info->e_wait_q[sr].list.prev; 455 if (ptr == &info->e_wait_q[sr].list) 456 return NULL; 457 return list_entry(ptr, struct ext_wait_queue, list); 458} 459 460/* Auxiliary functions to manipulate messages' list */ 461static void msg_insert(struct msg_msg *ptr, struct mqueue_inode_info *info) 462{ 463 int k; 464 465 k = info->attr.mq_curmsgs - 1; 466 while (k >= 0 && info->messages[k]->m_type >= ptr->m_type) { 467 info->messages[k + 1] = info->messages[k]; 468 k--; 469 } 470 info->attr.mq_curmsgs++; 471 info->qsize += ptr->m_ts; 472 info->messages[k + 1] = ptr; 473} 474 475static inline struct msg_msg *msg_get(struct mqueue_inode_info *info) 476{ 477 info->qsize -= info->messages[--info->attr.mq_curmsgs]->m_ts; 478 return info->messages[info->attr.mq_curmsgs]; 479} 480 481static inline void set_cookie(struct sk_buff *skb, char code) 482{ 483 ((char*)skb->data)[NOTIFY_COOKIE_LEN-1] = code; 484} 485 486/* 487 * The next function is only to split too long sys_mq_timedsend 488 */ 489static void __do_notify(struct mqueue_inode_info *info) 490{ 491 /* notification 492 * invoked when there is registered process and there isn't process 493 * waiting synchronously for message AND state of queue changed from 494 * empty to not empty. Here we are sure that no one is waiting 495 * synchronously. */ 496 if (info->notify_owner && 497 info->attr.mq_curmsgs == 1) { 498 struct siginfo sig_i; 499 switch (info->notify.sigev_notify) { 500 case SIGEV_NONE: 501 break; 502 case SIGEV_SIGNAL: 503 /* sends signal */ 504 505 sig_i.si_signo = info->notify.sigev_signo; 506 sig_i.si_errno = 0; 507 sig_i.si_code = SI_MESGQ; 508 sig_i.si_value = info->notify.sigev_value; 509 sig_i.si_pid = task_tgid_vnr(current); 510 sig_i.si_uid = current_uid(); 511 512 kill_pid_info(info->notify.sigev_signo, 513 &sig_i, info->notify_owner); 514 break; 515 case SIGEV_THREAD: 516 set_cookie(info->notify_cookie, NOTIFY_WOKENUP); 517 netlink_sendskb(info->notify_sock, info->notify_cookie); 518 break; 519 } 520 /* after notification unregisters process */ 521 put_pid(info->notify_owner); 522 info->notify_owner = NULL; 523 } 524 wake_up(&info->wait_q); 525} 526 527static long prepare_timeout(const struct timespec __user *u_arg) 528{ 529 struct timespec ts, nowts; 530 long timeout; 531 532 if (u_arg) { 533 if (unlikely(copy_from_user(&ts, u_arg, 534 sizeof(struct timespec)))) 535 return -EFAULT; 536 537 if (unlikely(ts.tv_nsec < 0 || ts.tv_sec < 0 538 || ts.tv_nsec >= NSEC_PER_SEC)) 539 return -EINVAL; 540 nowts = CURRENT_TIME; 541 /* first subtract as jiffies can't be too big */ 542 ts.tv_sec -= nowts.tv_sec; 543 if (ts.tv_nsec < nowts.tv_nsec) { 544 ts.tv_nsec += NSEC_PER_SEC; 545 ts.tv_sec--; 546 } 547 ts.tv_nsec -= nowts.tv_nsec; 548 if (ts.tv_sec < 0) 549 return 0; 550 551 timeout = timespec_to_jiffies(&ts) + 1; 552 } else 553 return MAX_SCHEDULE_TIMEOUT; 554 555 return timeout; 556} 557 558static void remove_notification(struct mqueue_inode_info *info) 559{ 560 if (info->notify_owner != NULL && 561 info->notify.sigev_notify == SIGEV_THREAD) { 562 set_cookie(info->notify_cookie, NOTIFY_REMOVED); 563 netlink_sendskb(info->notify_sock, info->notify_cookie); 564 } 565 put_pid(info->notify_owner); 566 info->notify_owner = NULL; 567} 568 569static int mq_attr_ok(struct mq_attr *attr) 570{ 571 if (attr->mq_maxmsg <= 0 || attr->mq_msgsize <= 0) 572 return 0; 573 if (capable(CAP_SYS_RESOURCE)) { 574 if (attr->mq_maxmsg > HARD_MSGMAX) 575 return 0; 576 } else { 577 if (attr->mq_maxmsg > msg_max || 578 attr->mq_msgsize > msgsize_max) 579 return 0; 580 } 581 /* check for overflow */ 582 if (attr->mq_msgsize > ULONG_MAX/attr->mq_maxmsg) 583 return 0; 584 if ((unsigned long)(attr->mq_maxmsg * attr->mq_msgsize) + 585 (attr->mq_maxmsg * sizeof (struct msg_msg *)) < 586 (unsigned long)(attr->mq_maxmsg * attr->mq_msgsize)) 587 return 0; 588 return 1; 589} 590 591/* 592 * Invoked when creating a new queue via sys_mq_open 593 */ 594static struct file *do_create(struct dentry *dir, struct dentry *dentry, 595 int oflag, mode_t mode, struct mq_attr __user *u_attr) 596{ 597 struct mq_attr attr; 598 struct file *result; 599 int ret; 600 601 if (u_attr) { 602 ret = -EFAULT; 603 if (copy_from_user(&attr, u_attr, sizeof(attr))) 604 goto out; 605 ret = -EINVAL; 606 if (!mq_attr_ok(&attr)) 607 goto out; 608 /* store for use during create */ 609 dentry->d_fsdata = &attr; 610 } 611 612 mode &= ~current->fs->umask; 613 ret = mnt_want_write(mqueue_mnt); 614 if (ret) 615 goto out; 616 ret = vfs_create(dir->d_inode, dentry, mode, NULL); 617 dentry->d_fsdata = NULL; 618 if (ret) 619 goto out_drop_write; 620 621 result = dentry_open(dentry, mqueue_mnt, oflag); 622 /* 623 * dentry_open() took a persistent mnt_want_write(), 624 * so we can now drop this one. 625 */ 626 mnt_drop_write(mqueue_mnt); 627 return result; 628 629out_drop_write: 630 mnt_drop_write(mqueue_mnt); 631out: 632 dput(dentry); 633 mntput(mqueue_mnt); 634 return ERR_PTR(ret); 635} 636 637/* Opens existing queue */ 638static struct file *do_open(struct dentry *dentry, int oflag) 639{ 640static int oflag2acc[O_ACCMODE] = { MAY_READ, MAY_WRITE, 641 MAY_READ | MAY_WRITE }; 642 643 if ((oflag & O_ACCMODE) == (O_RDWR | O_WRONLY)) { 644 dput(dentry); 645 mntput(mqueue_mnt); 646 return ERR_PTR(-EINVAL); 647 } 648 649 if (inode_permission(dentry->d_inode, oflag2acc[oflag & O_ACCMODE])) { 650 dput(dentry); 651 mntput(mqueue_mnt); 652 return ERR_PTR(-EACCES); 653 } 654 655 return dentry_open(dentry, mqueue_mnt, oflag); 656} 657 658asmlinkage long sys_mq_open(const char __user *u_name, int oflag, mode_t mode, 659 struct mq_attr __user *u_attr) 660{ 661 struct dentry *dentry; 662 struct file *filp; 663 char *name; 664 int fd, error; 665 666 error = audit_mq_open(oflag, mode, u_attr); 667 if (error != 0) 668 return error; 669 670 if (IS_ERR(name = getname(u_name))) 671 return PTR_ERR(name); 672 673 fd = get_unused_fd_flags(O_CLOEXEC); 674 if (fd < 0) 675 goto out_putname; 676 677 mutex_lock(&mqueue_mnt->mnt_root->d_inode->i_mutex); 678 dentry = lookup_one_len(name, mqueue_mnt->mnt_root, strlen(name)); 679 if (IS_ERR(dentry)) { 680 error = PTR_ERR(dentry); 681 goto out_err; 682 } 683 mntget(mqueue_mnt); 684 685 if (oflag & O_CREAT) { 686 if (dentry->d_inode) { /* entry already exists */ 687 audit_inode(name, dentry); 688 error = -EEXIST; 689 if (oflag & O_EXCL) 690 goto out; 691 filp = do_open(dentry, oflag); 692 } else { 693 filp = do_create(mqueue_mnt->mnt_root, dentry, 694 oflag, mode, u_attr); 695 } 696 } else { 697 error = -ENOENT; 698 if (!dentry->d_inode) 699 goto out; 700 audit_inode(name, dentry); 701 filp = do_open(dentry, oflag); 702 } 703 704 if (IS_ERR(filp)) { 705 error = PTR_ERR(filp); 706 goto out_putfd; 707 } 708 709 fd_install(fd, filp); 710 goto out_upsem; 711 712out: 713 dput(dentry); 714 mntput(mqueue_mnt); 715out_putfd: 716 put_unused_fd(fd); 717out_err: 718 fd = error; 719out_upsem: 720 mutex_unlock(&mqueue_mnt->mnt_root->d_inode->i_mutex); 721out_putname: 722 putname(name); 723 return fd; 724} 725 726asmlinkage long sys_mq_unlink(const char __user *u_name) 727{ 728 int err; 729 char *name; 730 struct dentry *dentry; 731 struct inode *inode = NULL; 732 733 name = getname(u_name); 734 if (IS_ERR(name)) 735 return PTR_ERR(name); 736 737 mutex_lock_nested(&mqueue_mnt->mnt_root->d_inode->i_mutex, 738 I_MUTEX_PARENT); 739 dentry = lookup_one_len(name, mqueue_mnt->mnt_root, strlen(name)); 740 if (IS_ERR(dentry)) { 741 err = PTR_ERR(dentry); 742 goto out_unlock; 743 } 744 745 if (!dentry->d_inode) { 746 err = -ENOENT; 747 goto out_err; 748 } 749 750 inode = dentry->d_inode; 751 if (inode) 752 atomic_inc(&inode->i_count); 753 err = mnt_want_write(mqueue_mnt); 754 if (err) 755 goto out_err; 756 err = vfs_unlink(dentry->d_parent->d_inode, dentry); 757 mnt_drop_write(mqueue_mnt); 758out_err: 759 dput(dentry); 760 761out_unlock: 762 mutex_unlock(&mqueue_mnt->mnt_root->d_inode->i_mutex); 763 putname(name); 764 if (inode) 765 iput(inode); 766 767 return err; 768} 769 770/* Pipelined send and receive functions. 771 * 772 * If a receiver finds no waiting message, then it registers itself in the 773 * list of waiting receivers. A sender checks that list before adding the new 774 * message into the message array. If there is a waiting receiver, then it 775 * bypasses the message array and directly hands the message over to the 776 * receiver. 777 * The receiver accepts the message and returns without grabbing the queue 778 * spinlock. Therefore an intermediate STATE_PENDING state and memory barriers 779 * are necessary. The same algorithm is used for sysv semaphores, see 780 * ipc/sem.c for more details. 781 * 782 * The same algorithm is used for senders. 783 */ 784 785/* pipelined_send() - send a message directly to the task waiting in 786 * sys_mq_timedreceive() (without inserting message into a queue). 787 */ 788static inline void pipelined_send(struct mqueue_inode_info *info, 789 struct msg_msg *message, 790 struct ext_wait_queue *receiver) 791{ 792 receiver->msg = message; 793 list_del(&receiver->list); 794 receiver->state = STATE_PENDING; 795 wake_up_process(receiver->task); 796 smp_wmb(); 797 receiver->state = STATE_READY; 798} 799 800/* pipelined_receive() - if there is task waiting in sys_mq_timedsend() 801 * gets its message and put to the queue (we have one free place for sure). */ 802static inline void pipelined_receive(struct mqueue_inode_info *info) 803{ 804 struct ext_wait_queue *sender = wq_get_first_waiter(info, SEND); 805 806 if (!sender) { 807 /* for poll */ 808 wake_up_interruptible(&info->wait_q); 809 return; 810 } 811 msg_insert(sender->msg, info); 812 list_del(&sender->list); 813 sender->state = STATE_PENDING; 814 wake_up_process(sender->task); 815 smp_wmb(); 816 sender->state = STATE_READY; 817} 818 819asmlinkage long sys_mq_timedsend(mqd_t mqdes, const char __user *u_msg_ptr, 820 size_t msg_len, unsigned int msg_prio, 821 const struct timespec __user *u_abs_timeout) 822{ 823 struct file *filp; 824 struct inode *inode; 825 struct ext_wait_queue wait; 826 struct ext_wait_queue *receiver; 827 struct msg_msg *msg_ptr; 828 struct mqueue_inode_info *info; 829 long timeout; 830 int ret; 831 832 ret = audit_mq_timedsend(mqdes, msg_len, msg_prio, u_abs_timeout); 833 if (ret != 0) 834 return ret; 835 836 if (unlikely(msg_prio >= (unsigned long) MQ_PRIO_MAX)) 837 return -EINVAL; 838 839 timeout = prepare_timeout(u_abs_timeout); 840 841 ret = -EBADF; 842 filp = fget(mqdes); 843 if (unlikely(!filp)) 844 goto out; 845 846 inode = filp->f_path.dentry->d_inode; 847 if (unlikely(filp->f_op != &mqueue_file_operations)) 848 goto out_fput; 849 info = MQUEUE_I(inode); 850 audit_inode(NULL, filp->f_path.dentry); 851 852 if (unlikely(!(filp->f_mode & FMODE_WRITE))) 853 goto out_fput; 854 855 if (unlikely(msg_len > info->attr.mq_msgsize)) { 856 ret = -EMSGSIZE; 857 goto out_fput; 858 } 859 860 /* First try to allocate memory, before doing anything with 861 * existing queues. */ 862 msg_ptr = load_msg(u_msg_ptr, msg_len); 863 if (IS_ERR(msg_ptr)) { 864 ret = PTR_ERR(msg_ptr); 865 goto out_fput; 866 } 867 msg_ptr->m_ts = msg_len; 868 msg_ptr->m_type = msg_prio; 869 870 spin_lock(&info->lock); 871 872 if (info->attr.mq_curmsgs == info->attr.mq_maxmsg) { 873 if (filp->f_flags & O_NONBLOCK) { 874 spin_unlock(&info->lock); 875 ret = -EAGAIN; 876 } else if (unlikely(timeout < 0)) { 877 spin_unlock(&info->lock); 878 ret = timeout; 879 } else { 880 wait.task = current; 881 wait.msg = (void *) msg_ptr; 882 wait.state = STATE_NONE; 883 ret = wq_sleep(info, SEND, timeout, &wait); 884 } 885 if (ret < 0) 886 free_msg(msg_ptr); 887 } else { 888 receiver = wq_get_first_waiter(info, RECV); 889 if (receiver) { 890 pipelined_send(info, msg_ptr, receiver); 891 } else { 892 /* adds message to the queue */ 893 msg_insert(msg_ptr, info); 894 __do_notify(info); 895 } 896 inode->i_atime = inode->i_mtime = inode->i_ctime = 897 CURRENT_TIME; 898 spin_unlock(&info->lock); 899 ret = 0; 900 } 901out_fput: 902 fput(filp); 903out: 904 return ret; 905} 906 907asmlinkage ssize_t sys_mq_timedreceive(mqd_t mqdes, char __user *u_msg_ptr, 908 size_t msg_len, unsigned int __user *u_msg_prio, 909 const struct timespec __user *u_abs_timeout) 910{ 911 long timeout; 912 ssize_t ret; 913 struct msg_msg *msg_ptr; 914 struct file *filp; 915 struct inode *inode; 916 struct mqueue_inode_info *info; 917 struct ext_wait_queue wait; 918 919 ret = audit_mq_timedreceive(mqdes, msg_len, u_msg_prio, u_abs_timeout); 920 if (ret != 0) 921 return ret; 922 923 timeout = prepare_timeout(u_abs_timeout); 924 925 ret = -EBADF; 926 filp = fget(mqdes); 927 if (unlikely(!filp)) 928 goto out; 929 930 inode = filp->f_path.dentry->d_inode; 931 if (unlikely(filp->f_op != &mqueue_file_operations)) 932 goto out_fput; 933 info = MQUEUE_I(inode); 934 audit_inode(NULL, filp->f_path.dentry); 935 936 if (unlikely(!(filp->f_mode & FMODE_READ))) 937 goto out_fput; 938 939 /* checks if buffer is big enough */ 940 if (unlikely(msg_len < info->attr.mq_msgsize)) { 941 ret = -EMSGSIZE; 942 goto out_fput; 943 } 944 945 spin_lock(&info->lock); 946 if (info->attr.mq_curmsgs == 0) { 947 if (filp->f_flags & O_NONBLOCK) { 948 spin_unlock(&info->lock); 949 ret = -EAGAIN; 950 msg_ptr = NULL; 951 } else if (unlikely(timeout < 0)) { 952 spin_unlock(&info->lock); 953 ret = timeout; 954 msg_ptr = NULL; 955 } else { 956 wait.task = current; 957 wait.state = STATE_NONE; 958 ret = wq_sleep(info, RECV, timeout, &wait); 959 msg_ptr = wait.msg; 960 } 961 } else { 962 msg_ptr = msg_get(info); 963 964 inode->i_atime = inode->i_mtime = inode->i_ctime = 965 CURRENT_TIME; 966 967 /* There is now free space in queue. */ 968 pipelined_receive(info); 969 spin_unlock(&info->lock); 970 ret = 0; 971 } 972 if (ret == 0) { 973 ret = msg_ptr->m_ts; 974 975 if ((u_msg_prio && put_user(msg_ptr->m_type, u_msg_prio)) || 976 store_msg(u_msg_ptr, msg_ptr, msg_ptr->m_ts)) { 977 ret = -EFAULT; 978 } 979 free_msg(msg_ptr); 980 } 981out_fput: 982 fput(filp); 983out: 984 return ret; 985} 986 987/* 988 * Notes: the case when user wants us to deregister (with NULL as pointer) 989 * and he isn't currently owner of notification, will be silently discarded. 990 * It isn't explicitly defined in the POSIX. 991 */ 992asmlinkage long sys_mq_notify(mqd_t mqdes, 993 const struct sigevent __user *u_notification) 994{ 995 int ret; 996 struct file *filp; 997 struct sock *sock; 998 struct inode *inode; 999 struct sigevent notification; 1000 struct mqueue_inode_info *info; 1001 struct sk_buff *nc; 1002 1003 ret = audit_mq_notify(mqdes, u_notification); 1004 if (ret != 0) 1005 return ret; 1006 1007 nc = NULL; 1008 sock = NULL; 1009 if (u_notification != NULL) { 1010 if (copy_from_user(¬ification, u_notification, 1011 sizeof(struct sigevent))) 1012 return -EFAULT; 1013 1014 if (unlikely(notification.sigev_notify != SIGEV_NONE && 1015 notification.sigev_notify != SIGEV_SIGNAL && 1016 notification.sigev_notify != SIGEV_THREAD)) 1017 return -EINVAL; 1018 if (notification.sigev_notify == SIGEV_SIGNAL && 1019 !valid_signal(notification.sigev_signo)) { 1020 return -EINVAL; 1021 } 1022 if (notification.sigev_notify == SIGEV_THREAD) { 1023 long timeo; 1024 1025 /* create the notify skb */ 1026 nc = alloc_skb(NOTIFY_COOKIE_LEN, GFP_KERNEL); 1027 ret = -ENOMEM; 1028 if (!nc) 1029 goto out; 1030 ret = -EFAULT; 1031 if (copy_from_user(nc->data, 1032 notification.sigev_value.sival_ptr, 1033 NOTIFY_COOKIE_LEN)) { 1034 goto out; 1035 } 1036 1037 /* TODO: add a header? */ 1038 skb_put(nc, NOTIFY_COOKIE_LEN); 1039 /* and attach it to the socket */ 1040retry: 1041 filp = fget(notification.sigev_signo); 1042 ret = -EBADF; 1043 if (!filp) 1044 goto out; 1045 sock = netlink_getsockbyfilp(filp); 1046 fput(filp); 1047 if (IS_ERR(sock)) { 1048 ret = PTR_ERR(sock); 1049 sock = NULL; 1050 goto out; 1051 } 1052 1053 timeo = MAX_SCHEDULE_TIMEOUT; 1054 ret = netlink_attachskb(sock, nc, &timeo, NULL); 1055 if (ret == 1) 1056 goto retry; 1057 if (ret) { 1058 sock = NULL; 1059 nc = NULL; 1060 goto out; 1061 } 1062 } 1063 } 1064 1065 ret = -EBADF; 1066 filp = fget(mqdes); 1067 if (!filp) 1068 goto out; 1069 1070 inode = filp->f_path.dentry->d_inode; 1071 if (unlikely(filp->f_op != &mqueue_file_operations)) 1072 goto out_fput; 1073 info = MQUEUE_I(inode); 1074 1075 ret = 0; 1076 spin_lock(&info->lock); 1077 if (u_notification == NULL) { 1078 if (info->notify_owner == task_tgid(current)) { 1079 remove_notification(info); 1080 inode->i_atime = inode->i_ctime = CURRENT_TIME; 1081 } 1082 } else if (info->notify_owner != NULL) { 1083 ret = -EBUSY; 1084 } else { 1085 switch (notification.sigev_notify) { 1086 case SIGEV_NONE: 1087 info->notify.sigev_notify = SIGEV_NONE; 1088 break; 1089 case SIGEV_THREAD: 1090 info->notify_sock = sock; 1091 info->notify_cookie = nc; 1092 sock = NULL; 1093 nc = NULL; 1094 info->notify.sigev_notify = SIGEV_THREAD; 1095 break; 1096 case SIGEV_SIGNAL: 1097 info->notify.sigev_signo = notification.sigev_signo; 1098 info->notify.sigev_value = notification.sigev_value; 1099 info->notify.sigev_notify = SIGEV_SIGNAL; 1100 break; 1101 } 1102 1103 info->notify_owner = get_pid(task_tgid(current)); 1104 inode->i_atime = inode->i_ctime = CURRENT_TIME; 1105 } 1106 spin_unlock(&info->lock); 1107out_fput: 1108 fput(filp); 1109out: 1110 if (sock) { 1111 netlink_detachskb(sock, nc); 1112 } else if (nc) { 1113 dev_kfree_skb(nc); 1114 } 1115 return ret; 1116} 1117 1118asmlinkage long sys_mq_getsetattr(mqd_t mqdes, 1119 const struct mq_attr __user *u_mqstat, 1120 struct mq_attr __user *u_omqstat) 1121{ 1122 int ret; 1123 struct mq_attr mqstat, omqstat; 1124 struct file *filp; 1125 struct inode *inode; 1126 struct mqueue_inode_info *info; 1127 1128 if (u_mqstat != NULL) { 1129 if (copy_from_user(&mqstat, u_mqstat, sizeof(struct mq_attr))) 1130 return -EFAULT; 1131 if (mqstat.mq_flags & (~O_NONBLOCK)) 1132 return -EINVAL; 1133 } 1134 1135 ret = -EBADF; 1136 filp = fget(mqdes); 1137 if (!filp) 1138 goto out; 1139 1140 inode = filp->f_path.dentry->d_inode; 1141 if (unlikely(filp->f_op != &mqueue_file_operations)) 1142 goto out_fput; 1143 info = MQUEUE_I(inode); 1144 1145 spin_lock(&info->lock); 1146 1147 omqstat = info->attr; 1148 omqstat.mq_flags = filp->f_flags & O_NONBLOCK; 1149 if (u_mqstat) { 1150 ret = audit_mq_getsetattr(mqdes, &mqstat); 1151 if (ret != 0) { 1152 spin_unlock(&info->lock); 1153 goto out_fput; 1154 } 1155 if (mqstat.mq_flags & O_NONBLOCK) 1156 filp->f_flags |= O_NONBLOCK; 1157 else 1158 filp->f_flags &= ~O_NONBLOCK; 1159 1160 inode->i_atime = inode->i_ctime = CURRENT_TIME; 1161 } 1162 1163 spin_unlock(&info->lock); 1164 1165 ret = 0; 1166 if (u_omqstat != NULL && copy_to_user(u_omqstat, &omqstat, 1167 sizeof(struct mq_attr))) 1168 ret = -EFAULT; 1169 1170out_fput: 1171 fput(filp); 1172out: 1173 return ret; 1174} 1175 1176static const struct inode_operations mqueue_dir_inode_operations = { 1177 .lookup = simple_lookup, 1178 .create = mqueue_create, 1179 .unlink = mqueue_unlink, 1180}; 1181 1182static const struct file_operations mqueue_file_operations = { 1183 .flush = mqueue_flush_file, 1184 .poll = mqueue_poll_file, 1185 .read = mqueue_read_file, 1186}; 1187 1188static struct super_operations mqueue_super_ops = { 1189 .alloc_inode = mqueue_alloc_inode, 1190 .destroy_inode = mqueue_destroy_inode, 1191 .statfs = simple_statfs, 1192 .delete_inode = mqueue_delete_inode, 1193 .drop_inode = generic_delete_inode, 1194}; 1195 1196static struct file_system_type mqueue_fs_type = { 1197 .name = "mqueue", 1198 .get_sb = mqueue_get_sb, 1199 .kill_sb = kill_litter_super, 1200}; 1201 1202static int msg_max_limit_min = MIN_MSGMAX; 1203static int msg_max_limit_max = MAX_MSGMAX; 1204 1205static int msg_maxsize_limit_min = MIN_MSGSIZEMAX; 1206static int msg_maxsize_limit_max = MAX_MSGSIZEMAX; 1207 1208static ctl_table mq_sysctls[] = { 1209 { 1210 .procname = "queues_max", 1211 .data = &queues_max, 1212 .maxlen = sizeof(int), 1213 .mode = 0644, 1214 .proc_handler = &proc_dointvec, 1215 }, 1216 { 1217 .procname = "msg_max", 1218 .data = &msg_max, 1219 .maxlen = sizeof(int), 1220 .mode = 0644, 1221 .proc_handler = &proc_dointvec_minmax, 1222 .extra1 = &msg_max_limit_min, 1223 .extra2 = &msg_max_limit_max, 1224 }, 1225 { 1226 .procname = "msgsize_max", 1227 .data = &msgsize_max, 1228 .maxlen = sizeof(int), 1229 .mode = 0644, 1230 .proc_handler = &proc_dointvec_minmax, 1231 .extra1 = &msg_maxsize_limit_min, 1232 .extra2 = &msg_maxsize_limit_max, 1233 }, 1234 { .ctl_name = 0 } 1235}; 1236 1237static ctl_table mq_sysctl_dir[] = { 1238 { 1239 .procname = "mqueue", 1240 .mode = 0555, 1241 .child = mq_sysctls, 1242 }, 1243 { .ctl_name = 0 } 1244}; 1245 1246static ctl_table mq_sysctl_root[] = { 1247 { 1248 .ctl_name = CTL_FS, 1249 .procname = "fs", 1250 .mode = 0555, 1251 .child = mq_sysctl_dir, 1252 }, 1253 { .ctl_name = 0 } 1254}; 1255 1256static int __init init_mqueue_fs(void) 1257{ 1258 int error; 1259 1260 mqueue_inode_cachep = kmem_cache_create("mqueue_inode_cache", 1261 sizeof(struct mqueue_inode_info), 0, 1262 SLAB_HWCACHE_ALIGN, init_once); 1263 if (mqueue_inode_cachep == NULL) 1264 return -ENOMEM; 1265 1266 /* ignore failues - they are not fatal */ 1267 mq_sysctl_table = register_sysctl_table(mq_sysctl_root); 1268 1269 error = register_filesystem(&mqueue_fs_type); 1270 if (error) 1271 goto out_sysctl; 1272 1273 if (IS_ERR(mqueue_mnt = kern_mount(&mqueue_fs_type))) { 1274 error = PTR_ERR(mqueue_mnt); 1275 goto out_filesystem; 1276 } 1277 1278 /* internal initialization - not common for vfs */ 1279 queues_count = 0; 1280 spin_lock_init(&mq_lock); 1281 1282 return 0; 1283 1284out_filesystem: 1285 unregister_filesystem(&mqueue_fs_type); 1286out_sysctl: 1287 if (mq_sysctl_table) 1288 unregister_sysctl_table(mq_sysctl_table); 1289 kmem_cache_destroy(mqueue_inode_cachep); 1290 return error; 1291} 1292 1293__initcall(init_mqueue_fs); 1294