mqueue.c revision ceefda6931806972ecf550bd8231dce4a4178953
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#include <linux/ipc_namespace.h> 35#include <linux/slab.h> 36 37#include <net/sock.h> 38#include "util.h" 39 40#define MQUEUE_MAGIC 0x19800202 41#define DIRENT_SIZE 20 42#define FILENT_SIZE 80 43 44#define SEND 0 45#define RECV 1 46 47#define STATE_NONE 0 48#define STATE_PENDING 1 49#define STATE_READY 2 50 51struct ext_wait_queue { /* queue of sleeping tasks */ 52 struct task_struct *task; 53 struct list_head list; 54 struct msg_msg *msg; /* ptr of loaded message */ 55 int state; /* one of STATE_* values */ 56}; 57 58struct mqueue_inode_info { 59 spinlock_t lock; 60 struct inode vfs_inode; 61 wait_queue_head_t wait_q; 62 63 struct msg_msg **messages; 64 struct mq_attr attr; 65 66 struct sigevent notify; 67 struct pid* notify_owner; 68 struct user_struct *user; /* user who created, for accounting */ 69 struct sock *notify_sock; 70 struct sk_buff *notify_cookie; 71 72 /* for tasks waiting for free space and messages, respectively */ 73 struct ext_wait_queue e_wait_q[2]; 74 75 unsigned long qsize; /* size of queue in memory (sum of all msgs) */ 76}; 77 78static const struct inode_operations mqueue_dir_inode_operations; 79static const struct file_operations mqueue_file_operations; 80static const struct super_operations mqueue_super_ops; 81static void remove_notification(struct mqueue_inode_info *info); 82 83static struct kmem_cache *mqueue_inode_cachep; 84 85static struct ctl_table_header * mq_sysctl_table; 86 87static inline struct mqueue_inode_info *MQUEUE_I(struct inode *inode) 88{ 89 return container_of(inode, struct mqueue_inode_info, vfs_inode); 90} 91 92/* 93 * This routine should be called with the mq_lock held. 94 */ 95static inline struct ipc_namespace *__get_ns_from_inode(struct inode *inode) 96{ 97 return get_ipc_ns(inode->i_sb->s_fs_info); 98} 99 100static struct ipc_namespace *get_ns_from_inode(struct inode *inode) 101{ 102 struct ipc_namespace *ns; 103 104 spin_lock(&mq_lock); 105 ns = __get_ns_from_inode(inode); 106 spin_unlock(&mq_lock); 107 return ns; 108} 109 110static struct inode *mqueue_get_inode(struct super_block *sb, 111 struct ipc_namespace *ipc_ns, int mode, 112 struct mq_attr *attr) 113{ 114 struct user_struct *u = current_user(); 115 struct inode *inode; 116 117 inode = new_inode(sb); 118 if (inode) { 119 inode->i_ino = get_next_ino(); 120 inode->i_mode = mode; 121 inode->i_uid = current_fsuid(); 122 inode->i_gid = current_fsgid(); 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 unsigned long mq_bytes, mq_msg_tblsz; 130 131 inode->i_fop = &mqueue_file_operations; 132 inode->i_size = FILENT_SIZE; 133 /* mqueue specific info */ 134 info = MQUEUE_I(inode); 135 spin_lock_init(&info->lock); 136 init_waitqueue_head(&info->wait_q); 137 INIT_LIST_HEAD(&info->e_wait_q[0].list); 138 INIT_LIST_HEAD(&info->e_wait_q[1].list); 139 info->notify_owner = NULL; 140 info->qsize = 0; 141 info->user = NULL; /* set when all is ok */ 142 memset(&info->attr, 0, sizeof(info->attr)); 143 info->attr.mq_maxmsg = ipc_ns->mq_msg_max; 144 info->attr.mq_msgsize = ipc_ns->mq_msgsize_max; 145 if (attr) { 146 info->attr.mq_maxmsg = attr->mq_maxmsg; 147 info->attr.mq_msgsize = attr->mq_msgsize; 148 } 149 mq_msg_tblsz = info->attr.mq_maxmsg * sizeof(struct msg_msg *); 150 info->messages = kmalloc(mq_msg_tblsz, GFP_KERNEL); 151 if (!info->messages) 152 goto out_inode; 153 154 mq_bytes = (mq_msg_tblsz + 155 (info->attr.mq_maxmsg * info->attr.mq_msgsize)); 156 157 spin_lock(&mq_lock); 158 if (u->mq_bytes + mq_bytes < u->mq_bytes || 159 u->mq_bytes + mq_bytes > 160 task_rlimit(p, RLIMIT_MSGQUEUE)) { 161 spin_unlock(&mq_lock); 162 /* mqueue_evict_inode() releases info->messages */ 163 goto out_inode; 164 } 165 u->mq_bytes += mq_bytes; 166 spin_unlock(&mq_lock); 167 168 /* all is ok */ 169 info->user = get_uid(u); 170 } else if (S_ISDIR(mode)) { 171 inc_nlink(inode); 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 iput(inode); 181 return NULL; 182} 183 184static int mqueue_fill_super(struct super_block *sb, void *data, int silent) 185{ 186 struct inode *inode; 187 struct ipc_namespace *ns = data; 188 int error; 189 190 sb->s_blocksize = PAGE_CACHE_SIZE; 191 sb->s_blocksize_bits = PAGE_CACHE_SHIFT; 192 sb->s_magic = MQUEUE_MAGIC; 193 sb->s_op = &mqueue_super_ops; 194 195 inode = mqueue_get_inode(sb, ns, S_IFDIR | S_ISVTX | S_IRWXUGO, 196 NULL); 197 if (!inode) { 198 error = -ENOMEM; 199 goto out; 200 } 201 202 sb->s_root = d_alloc_root(inode); 203 if (!sb->s_root) { 204 iput(inode); 205 error = -ENOMEM; 206 goto out; 207 } 208 error = 0; 209 210out: 211 return error; 212} 213 214static struct dentry *mqueue_mount(struct file_system_type *fs_type, 215 int flags, const char *dev_name, 216 void *data) 217{ 218 if (!(flags & MS_KERNMOUNT)) 219 data = current->nsproxy->ipc_ns; 220 return mount_ns(fs_type, flags, data, mqueue_fill_super); 221} 222 223static void init_once(void *foo) 224{ 225 struct mqueue_inode_info *p = (struct mqueue_inode_info *) foo; 226 227 inode_init_once(&p->vfs_inode); 228} 229 230static struct inode *mqueue_alloc_inode(struct super_block *sb) 231{ 232 struct mqueue_inode_info *ei; 233 234 ei = kmem_cache_alloc(mqueue_inode_cachep, GFP_KERNEL); 235 if (!ei) 236 return NULL; 237 return &ei->vfs_inode; 238} 239 240static void mqueue_destroy_inode(struct inode *inode) 241{ 242 kmem_cache_free(mqueue_inode_cachep, MQUEUE_I(inode)); 243} 244 245static void mqueue_evict_inode(struct inode *inode) 246{ 247 struct mqueue_inode_info *info; 248 struct user_struct *user; 249 unsigned long mq_bytes; 250 int i; 251 struct ipc_namespace *ipc_ns; 252 253 end_writeback(inode); 254 255 if (S_ISDIR(inode->i_mode)) 256 return; 257 258 ipc_ns = get_ns_from_inode(inode); 259 info = MQUEUE_I(inode); 260 spin_lock(&info->lock); 261 for (i = 0; i < info->attr.mq_curmsgs; i++) 262 free_msg(info->messages[i]); 263 kfree(info->messages); 264 spin_unlock(&info->lock); 265 266 /* Total amount of bytes accounted for the mqueue */ 267 mq_bytes = info->attr.mq_maxmsg * (sizeof(struct msg_msg *) 268 + info->attr.mq_msgsize); 269 user = info->user; 270 if (user) { 271 spin_lock(&mq_lock); 272 user->mq_bytes -= mq_bytes; 273 /* 274 * get_ns_from_inode() ensures that the 275 * (ipc_ns = sb->s_fs_info) is either a valid ipc_ns 276 * to which we now hold a reference, or it is NULL. 277 * We can't put it here under mq_lock, though. 278 */ 279 if (ipc_ns) 280 ipc_ns->mq_queues_count--; 281 spin_unlock(&mq_lock); 282 free_uid(user); 283 } 284 if (ipc_ns) 285 put_ipc_ns(ipc_ns); 286} 287 288static int mqueue_create(struct inode *dir, struct dentry *dentry, 289 int mode, struct nameidata *nd) 290{ 291 struct inode *inode; 292 struct mq_attr *attr = dentry->d_fsdata; 293 int error; 294 struct ipc_namespace *ipc_ns; 295 296 spin_lock(&mq_lock); 297 ipc_ns = __get_ns_from_inode(dir); 298 if (!ipc_ns) { 299 error = -EACCES; 300 goto out_unlock; 301 } 302 if (ipc_ns->mq_queues_count >= ipc_ns->mq_queues_max && 303 !capable(CAP_SYS_RESOURCE)) { 304 error = -ENOSPC; 305 goto out_unlock; 306 } 307 ipc_ns->mq_queues_count++; 308 spin_unlock(&mq_lock); 309 310 inode = mqueue_get_inode(dir->i_sb, ipc_ns, mode, attr); 311 if (!inode) { 312 error = -ENOMEM; 313 spin_lock(&mq_lock); 314 ipc_ns->mq_queues_count--; 315 goto out_unlock; 316 } 317 318 put_ipc_ns(ipc_ns); 319 dir->i_size += DIRENT_SIZE; 320 dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME; 321 322 d_instantiate(dentry, inode); 323 dget(dentry); 324 return 0; 325out_unlock: 326 spin_unlock(&mq_lock); 327 if (ipc_ns) 328 put_ipc_ns(ipc_ns); 329 return error; 330} 331 332static int mqueue_unlink(struct inode *dir, struct dentry *dentry) 333{ 334 struct inode *inode = dentry->d_inode; 335 336 dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME; 337 dir->i_size -= DIRENT_SIZE; 338 drop_nlink(inode); 339 dput(dentry); 340 return 0; 341} 342 343/* 344* This is routine for system read from queue file. 345* To avoid mess with doing here some sort of mq_receive we allow 346* to read only queue size & notification info (the only values 347* that are interesting from user point of view and aren't accessible 348* through std routines) 349*/ 350static ssize_t mqueue_read_file(struct file *filp, char __user *u_data, 351 size_t count, loff_t *off) 352{ 353 struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode); 354 char buffer[FILENT_SIZE]; 355 ssize_t ret; 356 357 spin_lock(&info->lock); 358 snprintf(buffer, sizeof(buffer), 359 "QSIZE:%-10lu NOTIFY:%-5d SIGNO:%-5d NOTIFY_PID:%-6d\n", 360 info->qsize, 361 info->notify_owner ? info->notify.sigev_notify : 0, 362 (info->notify_owner && 363 info->notify.sigev_notify == SIGEV_SIGNAL) ? 364 info->notify.sigev_signo : 0, 365 pid_vnr(info->notify_owner)); 366 spin_unlock(&info->lock); 367 buffer[sizeof(buffer)-1] = '\0'; 368 369 ret = simple_read_from_buffer(u_data, count, off, buffer, 370 strlen(buffer)); 371 if (ret <= 0) 372 return ret; 373 374 filp->f_path.dentry->d_inode->i_atime = filp->f_path.dentry->d_inode->i_ctime = CURRENT_TIME; 375 return ret; 376} 377 378static int mqueue_flush_file(struct file *filp, fl_owner_t id) 379{ 380 struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode); 381 382 spin_lock(&info->lock); 383 if (task_tgid(current) == info->notify_owner) 384 remove_notification(info); 385 386 spin_unlock(&info->lock); 387 return 0; 388} 389 390static unsigned int mqueue_poll_file(struct file *filp, struct poll_table_struct *poll_tab) 391{ 392 struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode); 393 int retval = 0; 394 395 poll_wait(filp, &info->wait_q, poll_tab); 396 397 spin_lock(&info->lock); 398 if (info->attr.mq_curmsgs) 399 retval = POLLIN | POLLRDNORM; 400 401 if (info->attr.mq_curmsgs < info->attr.mq_maxmsg) 402 retval |= POLLOUT | POLLWRNORM; 403 spin_unlock(&info->lock); 404 405 return retval; 406} 407 408/* Adds current to info->e_wait_q[sr] before element with smaller prio */ 409static void wq_add(struct mqueue_inode_info *info, int sr, 410 struct ext_wait_queue *ewp) 411{ 412 struct ext_wait_queue *walk; 413 414 ewp->task = current; 415 416 list_for_each_entry(walk, &info->e_wait_q[sr].list, list) { 417 if (walk->task->static_prio <= current->static_prio) { 418 list_add_tail(&ewp->list, &walk->list); 419 return; 420 } 421 } 422 list_add_tail(&ewp->list, &info->e_wait_q[sr].list); 423} 424 425/* 426 * Puts current task to sleep. Caller must hold queue lock. After return 427 * lock isn't held. 428 * sr: SEND or RECV 429 */ 430static int wq_sleep(struct mqueue_inode_info *info, int sr, 431 ktime_t *timeout, struct ext_wait_queue *ewp) 432{ 433 int retval; 434 signed long time; 435 436 wq_add(info, sr, ewp); 437 438 for (;;) { 439 set_current_state(TASK_INTERRUPTIBLE); 440 441 spin_unlock(&info->lock); 442 time = schedule_hrtimeout_range_clock(timeout, 443 HRTIMER_MODE_ABS, 0, CLOCK_REALTIME); 444 445 while (ewp->state == STATE_PENDING) 446 cpu_relax(); 447 448 if (ewp->state == STATE_READY) { 449 retval = 0; 450 goto out; 451 } 452 spin_lock(&info->lock); 453 if (ewp->state == STATE_READY) { 454 retval = 0; 455 goto out_unlock; 456 } 457 if (signal_pending(current)) { 458 retval = -ERESTARTSYS; 459 break; 460 } 461 if (time == 0) { 462 retval = -ETIMEDOUT; 463 break; 464 } 465 } 466 list_del(&ewp->list); 467out_unlock: 468 spin_unlock(&info->lock); 469out: 470 return retval; 471} 472 473/* 474 * Returns waiting task that should be serviced first or NULL if none exists 475 */ 476static struct ext_wait_queue *wq_get_first_waiter( 477 struct mqueue_inode_info *info, int sr) 478{ 479 struct list_head *ptr; 480 481 ptr = info->e_wait_q[sr].list.prev; 482 if (ptr == &info->e_wait_q[sr].list) 483 return NULL; 484 return list_entry(ptr, struct ext_wait_queue, list); 485} 486 487/* Auxiliary functions to manipulate messages' list */ 488static void msg_insert(struct msg_msg *ptr, struct mqueue_inode_info *info) 489{ 490 int k; 491 492 k = info->attr.mq_curmsgs - 1; 493 while (k >= 0 && info->messages[k]->m_type >= ptr->m_type) { 494 info->messages[k + 1] = info->messages[k]; 495 k--; 496 } 497 info->attr.mq_curmsgs++; 498 info->qsize += ptr->m_ts; 499 info->messages[k + 1] = ptr; 500} 501 502static inline struct msg_msg *msg_get(struct mqueue_inode_info *info) 503{ 504 info->qsize -= info->messages[--info->attr.mq_curmsgs]->m_ts; 505 return info->messages[info->attr.mq_curmsgs]; 506} 507 508static inline void set_cookie(struct sk_buff *skb, char code) 509{ 510 ((char*)skb->data)[NOTIFY_COOKIE_LEN-1] = code; 511} 512 513/* 514 * The next function is only to split too long sys_mq_timedsend 515 */ 516static void __do_notify(struct mqueue_inode_info *info) 517{ 518 /* notification 519 * invoked when there is registered process and there isn't process 520 * waiting synchronously for message AND state of queue changed from 521 * empty to not empty. Here we are sure that no one is waiting 522 * synchronously. */ 523 if (info->notify_owner && 524 info->attr.mq_curmsgs == 1) { 525 struct siginfo sig_i; 526 switch (info->notify.sigev_notify) { 527 case SIGEV_NONE: 528 break; 529 case SIGEV_SIGNAL: 530 /* sends signal */ 531 532 sig_i.si_signo = info->notify.sigev_signo; 533 sig_i.si_errno = 0; 534 sig_i.si_code = SI_MESGQ; 535 sig_i.si_value = info->notify.sigev_value; 536 sig_i.si_pid = task_tgid_nr_ns(current, 537 ns_of_pid(info->notify_owner)); 538 sig_i.si_uid = current_uid(); 539 540 kill_pid_info(info->notify.sigev_signo, 541 &sig_i, info->notify_owner); 542 break; 543 case SIGEV_THREAD: 544 set_cookie(info->notify_cookie, NOTIFY_WOKENUP); 545 netlink_sendskb(info->notify_sock, info->notify_cookie); 546 break; 547 } 548 /* after notification unregisters process */ 549 put_pid(info->notify_owner); 550 info->notify_owner = NULL; 551 } 552 wake_up(&info->wait_q); 553} 554 555static int prepare_timeout(const struct timespec __user *u_abs_timeout, 556 ktime_t *expires, struct timespec *ts) 557{ 558 if (copy_from_user(ts, u_abs_timeout, sizeof(struct timespec))) 559 return -EFAULT; 560 if (!timespec_valid(ts)) 561 return -EINVAL; 562 563 *expires = timespec_to_ktime(*ts); 564 return 0; 565} 566 567static void remove_notification(struct mqueue_inode_info *info) 568{ 569 if (info->notify_owner != NULL && 570 info->notify.sigev_notify == SIGEV_THREAD) { 571 set_cookie(info->notify_cookie, NOTIFY_REMOVED); 572 netlink_sendskb(info->notify_sock, info->notify_cookie); 573 } 574 put_pid(info->notify_owner); 575 info->notify_owner = NULL; 576} 577 578static int mq_attr_ok(struct ipc_namespace *ipc_ns, struct mq_attr *attr) 579{ 580 if (attr->mq_maxmsg <= 0 || attr->mq_msgsize <= 0) 581 return 0; 582 if (capable(CAP_SYS_RESOURCE)) { 583 if (attr->mq_maxmsg > HARD_MSGMAX) 584 return 0; 585 } else { 586 if (attr->mq_maxmsg > ipc_ns->mq_msg_max || 587 attr->mq_msgsize > ipc_ns->mq_msgsize_max) 588 return 0; 589 } 590 /* check for overflow */ 591 if (attr->mq_msgsize > ULONG_MAX/attr->mq_maxmsg) 592 return 0; 593 if ((unsigned long)(attr->mq_maxmsg * (attr->mq_msgsize 594 + sizeof (struct msg_msg *))) < 595 (unsigned long)(attr->mq_maxmsg * attr->mq_msgsize)) 596 return 0; 597 return 1; 598} 599 600/* 601 * Invoked when creating a new queue via sys_mq_open 602 */ 603static struct file *do_create(struct ipc_namespace *ipc_ns, struct dentry *dir, 604 struct dentry *dentry, int oflag, mode_t mode, 605 struct mq_attr *attr) 606{ 607 const struct cred *cred = current_cred(); 608 struct file *result; 609 int ret; 610 611 if (attr) { 612 if (!mq_attr_ok(ipc_ns, attr)) { 613 ret = -EINVAL; 614 goto out; 615 } 616 /* store for use during create */ 617 dentry->d_fsdata = attr; 618 } 619 620 mode &= ~current_umask(); 621 ret = mnt_want_write(ipc_ns->mq_mnt); 622 if (ret) 623 goto out; 624 ret = vfs_create(dir->d_inode, dentry, mode, NULL); 625 dentry->d_fsdata = NULL; 626 if (ret) 627 goto out_drop_write; 628 629 result = dentry_open(dentry, ipc_ns->mq_mnt, oflag, cred); 630 /* 631 * dentry_open() took a persistent mnt_want_write(), 632 * so we can now drop this one. 633 */ 634 mnt_drop_write(ipc_ns->mq_mnt); 635 return result; 636 637out_drop_write: 638 mnt_drop_write(ipc_ns->mq_mnt); 639out: 640 dput(dentry); 641 mntput(ipc_ns->mq_mnt); 642 return ERR_PTR(ret); 643} 644 645/* Opens existing queue */ 646static struct file *do_open(struct ipc_namespace *ipc_ns, 647 struct dentry *dentry, int oflag) 648{ 649 int ret; 650 const struct cred *cred = current_cred(); 651 652 static const int oflag2acc[O_ACCMODE] = { MAY_READ, MAY_WRITE, 653 MAY_READ | MAY_WRITE }; 654 655 if ((oflag & O_ACCMODE) == (O_RDWR | O_WRONLY)) { 656 ret = -EINVAL; 657 goto err; 658 } 659 660 if (inode_permission(dentry->d_inode, oflag2acc[oflag & O_ACCMODE])) { 661 ret = -EACCES; 662 goto err; 663 } 664 665 return dentry_open(dentry, ipc_ns->mq_mnt, oflag, cred); 666 667err: 668 dput(dentry); 669 mntput(ipc_ns->mq_mnt); 670 return ERR_PTR(ret); 671} 672 673SYSCALL_DEFINE4(mq_open, const char __user *, u_name, int, oflag, mode_t, mode, 674 struct mq_attr __user *, u_attr) 675{ 676 struct dentry *dentry; 677 struct file *filp; 678 char *name; 679 struct mq_attr attr; 680 int fd, error; 681 struct ipc_namespace *ipc_ns = current->nsproxy->ipc_ns; 682 683 if (u_attr && copy_from_user(&attr, u_attr, sizeof(struct mq_attr))) 684 return -EFAULT; 685 686 audit_mq_open(oflag, mode, u_attr ? &attr : NULL); 687 688 if (IS_ERR(name = getname(u_name))) 689 return PTR_ERR(name); 690 691 fd = get_unused_fd_flags(O_CLOEXEC); 692 if (fd < 0) 693 goto out_putname; 694 695 mutex_lock(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex); 696 dentry = lookup_one_len(name, ipc_ns->mq_mnt->mnt_root, strlen(name)); 697 if (IS_ERR(dentry)) { 698 error = PTR_ERR(dentry); 699 goto out_putfd; 700 } 701 mntget(ipc_ns->mq_mnt); 702 703 if (oflag & O_CREAT) { 704 if (dentry->d_inode) { /* entry already exists */ 705 audit_inode(name, dentry); 706 if (oflag & O_EXCL) { 707 error = -EEXIST; 708 goto out; 709 } 710 filp = do_open(ipc_ns, dentry, oflag); 711 } else { 712 filp = do_create(ipc_ns, ipc_ns->mq_mnt->mnt_root, 713 dentry, oflag, mode, 714 u_attr ? &attr : NULL); 715 } 716 } else { 717 if (!dentry->d_inode) { 718 error = -ENOENT; 719 goto out; 720 } 721 audit_inode(name, dentry); 722 filp = do_open(ipc_ns, dentry, oflag); 723 } 724 725 if (IS_ERR(filp)) { 726 error = PTR_ERR(filp); 727 goto out_putfd; 728 } 729 730 fd_install(fd, filp); 731 goto out_upsem; 732 733out: 734 dput(dentry); 735 mntput(ipc_ns->mq_mnt); 736out_putfd: 737 put_unused_fd(fd); 738 fd = error; 739out_upsem: 740 mutex_unlock(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex); 741out_putname: 742 putname(name); 743 return fd; 744} 745 746SYSCALL_DEFINE1(mq_unlink, const char __user *, u_name) 747{ 748 int err; 749 char *name; 750 struct dentry *dentry; 751 struct inode *inode = NULL; 752 struct ipc_namespace *ipc_ns = current->nsproxy->ipc_ns; 753 754 name = getname(u_name); 755 if (IS_ERR(name)) 756 return PTR_ERR(name); 757 758 mutex_lock_nested(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex, 759 I_MUTEX_PARENT); 760 dentry = lookup_one_len(name, ipc_ns->mq_mnt->mnt_root, strlen(name)); 761 if (IS_ERR(dentry)) { 762 err = PTR_ERR(dentry); 763 goto out_unlock; 764 } 765 766 if (!dentry->d_inode) { 767 err = -ENOENT; 768 goto out_err; 769 } 770 771 inode = dentry->d_inode; 772 if (inode) 773 ihold(inode); 774 err = mnt_want_write(ipc_ns->mq_mnt); 775 if (err) 776 goto out_err; 777 err = vfs_unlink(dentry->d_parent->d_inode, dentry); 778 mnt_drop_write(ipc_ns->mq_mnt); 779out_err: 780 dput(dentry); 781 782out_unlock: 783 mutex_unlock(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex); 784 putname(name); 785 if (inode) 786 iput(inode); 787 788 return err; 789} 790 791/* Pipelined send and receive functions. 792 * 793 * If a receiver finds no waiting message, then it registers itself in the 794 * list of waiting receivers. A sender checks that list before adding the new 795 * message into the message array. If there is a waiting receiver, then it 796 * bypasses the message array and directly hands the message over to the 797 * receiver. 798 * The receiver accepts the message and returns without grabbing the queue 799 * spinlock. Therefore an intermediate STATE_PENDING state and memory barriers 800 * are necessary. The same algorithm is used for sysv semaphores, see 801 * ipc/sem.c for more details. 802 * 803 * The same algorithm is used for senders. 804 */ 805 806/* pipelined_send() - send a message directly to the task waiting in 807 * sys_mq_timedreceive() (without inserting message into a queue). 808 */ 809static inline void pipelined_send(struct mqueue_inode_info *info, 810 struct msg_msg *message, 811 struct ext_wait_queue *receiver) 812{ 813 receiver->msg = message; 814 list_del(&receiver->list); 815 receiver->state = STATE_PENDING; 816 wake_up_process(receiver->task); 817 smp_wmb(); 818 receiver->state = STATE_READY; 819} 820 821/* pipelined_receive() - if there is task waiting in sys_mq_timedsend() 822 * gets its message and put to the queue (we have one free place for sure). */ 823static inline void pipelined_receive(struct mqueue_inode_info *info) 824{ 825 struct ext_wait_queue *sender = wq_get_first_waiter(info, SEND); 826 827 if (!sender) { 828 /* for poll */ 829 wake_up_interruptible(&info->wait_q); 830 return; 831 } 832 msg_insert(sender->msg, info); 833 list_del(&sender->list); 834 sender->state = STATE_PENDING; 835 wake_up_process(sender->task); 836 smp_wmb(); 837 sender->state = STATE_READY; 838} 839 840SYSCALL_DEFINE5(mq_timedsend, mqd_t, mqdes, const char __user *, u_msg_ptr, 841 size_t, msg_len, unsigned int, msg_prio, 842 const struct timespec __user *, u_abs_timeout) 843{ 844 struct file *filp; 845 struct inode *inode; 846 struct ext_wait_queue wait; 847 struct ext_wait_queue *receiver; 848 struct msg_msg *msg_ptr; 849 struct mqueue_inode_info *info; 850 ktime_t expires, *timeout = NULL; 851 struct timespec ts; 852 int ret; 853 854 if (u_abs_timeout) { 855 int res = prepare_timeout(u_abs_timeout, &expires, &ts); 856 if (res) 857 return res; 858 timeout = &expires; 859 } 860 861 if (unlikely(msg_prio >= (unsigned long) MQ_PRIO_MAX)) 862 return -EINVAL; 863 864 audit_mq_sendrecv(mqdes, msg_len, msg_prio, timeout ? &ts : NULL); 865 866 filp = fget(mqdes); 867 if (unlikely(!filp)) { 868 ret = -EBADF; 869 goto out; 870 } 871 872 inode = filp->f_path.dentry->d_inode; 873 if (unlikely(filp->f_op != &mqueue_file_operations)) { 874 ret = -EBADF; 875 goto out_fput; 876 } 877 info = MQUEUE_I(inode); 878 audit_inode(NULL, filp->f_path.dentry); 879 880 if (unlikely(!(filp->f_mode & FMODE_WRITE))) { 881 ret = -EBADF; 882 goto out_fput; 883 } 884 885 if (unlikely(msg_len > info->attr.mq_msgsize)) { 886 ret = -EMSGSIZE; 887 goto out_fput; 888 } 889 890 /* First try to allocate memory, before doing anything with 891 * existing queues. */ 892 msg_ptr = load_msg(u_msg_ptr, msg_len); 893 if (IS_ERR(msg_ptr)) { 894 ret = PTR_ERR(msg_ptr); 895 goto out_fput; 896 } 897 msg_ptr->m_ts = msg_len; 898 msg_ptr->m_type = msg_prio; 899 900 spin_lock(&info->lock); 901 902 if (info->attr.mq_curmsgs == info->attr.mq_maxmsg) { 903 if (filp->f_flags & O_NONBLOCK) { 904 spin_unlock(&info->lock); 905 ret = -EAGAIN; 906 } else { 907 wait.task = current; 908 wait.msg = (void *) msg_ptr; 909 wait.state = STATE_NONE; 910 ret = wq_sleep(info, SEND, timeout, &wait); 911 } 912 if (ret < 0) 913 free_msg(msg_ptr); 914 } else { 915 receiver = wq_get_first_waiter(info, RECV); 916 if (receiver) { 917 pipelined_send(info, msg_ptr, receiver); 918 } else { 919 /* adds message to the queue */ 920 msg_insert(msg_ptr, info); 921 __do_notify(info); 922 } 923 inode->i_atime = inode->i_mtime = inode->i_ctime = 924 CURRENT_TIME; 925 spin_unlock(&info->lock); 926 ret = 0; 927 } 928out_fput: 929 fput(filp); 930out: 931 return ret; 932} 933 934SYSCALL_DEFINE5(mq_timedreceive, mqd_t, mqdes, char __user *, u_msg_ptr, 935 size_t, msg_len, unsigned int __user *, u_msg_prio, 936 const struct timespec __user *, u_abs_timeout) 937{ 938 ssize_t ret; 939 struct msg_msg *msg_ptr; 940 struct file *filp; 941 struct inode *inode; 942 struct mqueue_inode_info *info; 943 struct ext_wait_queue wait; 944 ktime_t expires, *timeout = NULL; 945 struct timespec ts; 946 947 if (u_abs_timeout) { 948 int res = prepare_timeout(u_abs_timeout, &expires, &ts); 949 if (res) 950 return res; 951 timeout = &expires; 952 } 953 954 audit_mq_sendrecv(mqdes, msg_len, 0, timeout ? &ts : NULL); 955 956 filp = fget(mqdes); 957 if (unlikely(!filp)) { 958 ret = -EBADF; 959 goto out; 960 } 961 962 inode = filp->f_path.dentry->d_inode; 963 if (unlikely(filp->f_op != &mqueue_file_operations)) { 964 ret = -EBADF; 965 goto out_fput; 966 } 967 info = MQUEUE_I(inode); 968 audit_inode(NULL, filp->f_path.dentry); 969 970 if (unlikely(!(filp->f_mode & FMODE_READ))) { 971 ret = -EBADF; 972 goto out_fput; 973 } 974 975 /* checks if buffer is big enough */ 976 if (unlikely(msg_len < info->attr.mq_msgsize)) { 977 ret = -EMSGSIZE; 978 goto out_fput; 979 } 980 981 spin_lock(&info->lock); 982 if (info->attr.mq_curmsgs == 0) { 983 if (filp->f_flags & O_NONBLOCK) { 984 spin_unlock(&info->lock); 985 ret = -EAGAIN; 986 } else { 987 wait.task = current; 988 wait.state = STATE_NONE; 989 ret = wq_sleep(info, RECV, timeout, &wait); 990 msg_ptr = wait.msg; 991 } 992 } else { 993 msg_ptr = msg_get(info); 994 995 inode->i_atime = inode->i_mtime = inode->i_ctime = 996 CURRENT_TIME; 997 998 /* There is now free space in queue. */ 999 pipelined_receive(info); 1000 spin_unlock(&info->lock); 1001 ret = 0; 1002 } 1003 if (ret == 0) { 1004 ret = msg_ptr->m_ts; 1005 1006 if ((u_msg_prio && put_user(msg_ptr->m_type, u_msg_prio)) || 1007 store_msg(u_msg_ptr, msg_ptr, msg_ptr->m_ts)) { 1008 ret = -EFAULT; 1009 } 1010 free_msg(msg_ptr); 1011 } 1012out_fput: 1013 fput(filp); 1014out: 1015 return ret; 1016} 1017 1018/* 1019 * Notes: the case when user wants us to deregister (with NULL as pointer) 1020 * and he isn't currently owner of notification, will be silently discarded. 1021 * It isn't explicitly defined in the POSIX. 1022 */ 1023SYSCALL_DEFINE2(mq_notify, mqd_t, mqdes, 1024 const struct sigevent __user *, u_notification) 1025{ 1026 int ret; 1027 struct file *filp; 1028 struct sock *sock; 1029 struct inode *inode; 1030 struct sigevent notification; 1031 struct mqueue_inode_info *info; 1032 struct sk_buff *nc; 1033 1034 if (u_notification) { 1035 if (copy_from_user(¬ification, u_notification, 1036 sizeof(struct sigevent))) 1037 return -EFAULT; 1038 } 1039 1040 audit_mq_notify(mqdes, u_notification ? ¬ification : NULL); 1041 1042 nc = NULL; 1043 sock = NULL; 1044 if (u_notification != NULL) { 1045 if (unlikely(notification.sigev_notify != SIGEV_NONE && 1046 notification.sigev_notify != SIGEV_SIGNAL && 1047 notification.sigev_notify != SIGEV_THREAD)) 1048 return -EINVAL; 1049 if (notification.sigev_notify == SIGEV_SIGNAL && 1050 !valid_signal(notification.sigev_signo)) { 1051 return -EINVAL; 1052 } 1053 if (notification.sigev_notify == SIGEV_THREAD) { 1054 long timeo; 1055 1056 /* create the notify skb */ 1057 nc = alloc_skb(NOTIFY_COOKIE_LEN, GFP_KERNEL); 1058 if (!nc) { 1059 ret = -ENOMEM; 1060 goto out; 1061 } 1062 if (copy_from_user(nc->data, 1063 notification.sigev_value.sival_ptr, 1064 NOTIFY_COOKIE_LEN)) { 1065 ret = -EFAULT; 1066 goto out; 1067 } 1068 1069 /* TODO: add a header? */ 1070 skb_put(nc, NOTIFY_COOKIE_LEN); 1071 /* and attach it to the socket */ 1072retry: 1073 filp = fget(notification.sigev_signo); 1074 if (!filp) { 1075 ret = -EBADF; 1076 goto out; 1077 } 1078 sock = netlink_getsockbyfilp(filp); 1079 fput(filp); 1080 if (IS_ERR(sock)) { 1081 ret = PTR_ERR(sock); 1082 sock = NULL; 1083 goto out; 1084 } 1085 1086 timeo = MAX_SCHEDULE_TIMEOUT; 1087 ret = netlink_attachskb(sock, nc, &timeo, NULL); 1088 if (ret == 1) 1089 goto retry; 1090 if (ret) { 1091 sock = NULL; 1092 nc = NULL; 1093 goto out; 1094 } 1095 } 1096 } 1097 1098 filp = fget(mqdes); 1099 if (!filp) { 1100 ret = -EBADF; 1101 goto out; 1102 } 1103 1104 inode = filp->f_path.dentry->d_inode; 1105 if (unlikely(filp->f_op != &mqueue_file_operations)) { 1106 ret = -EBADF; 1107 goto out_fput; 1108 } 1109 info = MQUEUE_I(inode); 1110 1111 ret = 0; 1112 spin_lock(&info->lock); 1113 if (u_notification == NULL) { 1114 if (info->notify_owner == task_tgid(current)) { 1115 remove_notification(info); 1116 inode->i_atime = inode->i_ctime = CURRENT_TIME; 1117 } 1118 } else if (info->notify_owner != NULL) { 1119 ret = -EBUSY; 1120 } else { 1121 switch (notification.sigev_notify) { 1122 case SIGEV_NONE: 1123 info->notify.sigev_notify = SIGEV_NONE; 1124 break; 1125 case SIGEV_THREAD: 1126 info->notify_sock = sock; 1127 info->notify_cookie = nc; 1128 sock = NULL; 1129 nc = NULL; 1130 info->notify.sigev_notify = SIGEV_THREAD; 1131 break; 1132 case SIGEV_SIGNAL: 1133 info->notify.sigev_signo = notification.sigev_signo; 1134 info->notify.sigev_value = notification.sigev_value; 1135 info->notify.sigev_notify = SIGEV_SIGNAL; 1136 break; 1137 } 1138 1139 info->notify_owner = get_pid(task_tgid(current)); 1140 inode->i_atime = inode->i_ctime = CURRENT_TIME; 1141 } 1142 spin_unlock(&info->lock); 1143out_fput: 1144 fput(filp); 1145out: 1146 if (sock) { 1147 netlink_detachskb(sock, nc); 1148 } else if (nc) { 1149 dev_kfree_skb(nc); 1150 } 1151 return ret; 1152} 1153 1154SYSCALL_DEFINE3(mq_getsetattr, mqd_t, mqdes, 1155 const struct mq_attr __user *, u_mqstat, 1156 struct mq_attr __user *, u_omqstat) 1157{ 1158 int ret; 1159 struct mq_attr mqstat, omqstat; 1160 struct file *filp; 1161 struct inode *inode; 1162 struct mqueue_inode_info *info; 1163 1164 if (u_mqstat != NULL) { 1165 if (copy_from_user(&mqstat, u_mqstat, sizeof(struct mq_attr))) 1166 return -EFAULT; 1167 if (mqstat.mq_flags & (~O_NONBLOCK)) 1168 return -EINVAL; 1169 } 1170 1171 filp = fget(mqdes); 1172 if (!filp) { 1173 ret = -EBADF; 1174 goto out; 1175 } 1176 1177 inode = filp->f_path.dentry->d_inode; 1178 if (unlikely(filp->f_op != &mqueue_file_operations)) { 1179 ret = -EBADF; 1180 goto out_fput; 1181 } 1182 info = MQUEUE_I(inode); 1183 1184 spin_lock(&info->lock); 1185 1186 omqstat = info->attr; 1187 omqstat.mq_flags = filp->f_flags & O_NONBLOCK; 1188 if (u_mqstat) { 1189 audit_mq_getsetattr(mqdes, &mqstat); 1190 spin_lock(&filp->f_lock); 1191 if (mqstat.mq_flags & O_NONBLOCK) 1192 filp->f_flags |= O_NONBLOCK; 1193 else 1194 filp->f_flags &= ~O_NONBLOCK; 1195 spin_unlock(&filp->f_lock); 1196 1197 inode->i_atime = inode->i_ctime = CURRENT_TIME; 1198 } 1199 1200 spin_unlock(&info->lock); 1201 1202 ret = 0; 1203 if (u_omqstat != NULL && copy_to_user(u_omqstat, &omqstat, 1204 sizeof(struct mq_attr))) 1205 ret = -EFAULT; 1206 1207out_fput: 1208 fput(filp); 1209out: 1210 return ret; 1211} 1212 1213static const struct inode_operations mqueue_dir_inode_operations = { 1214 .lookup = simple_lookup, 1215 .create = mqueue_create, 1216 .unlink = mqueue_unlink, 1217}; 1218 1219static const struct file_operations mqueue_file_operations = { 1220 .flush = mqueue_flush_file, 1221 .poll = mqueue_poll_file, 1222 .read = mqueue_read_file, 1223 .llseek = default_llseek, 1224}; 1225 1226static const struct super_operations mqueue_super_ops = { 1227 .alloc_inode = mqueue_alloc_inode, 1228 .destroy_inode = mqueue_destroy_inode, 1229 .evict_inode = mqueue_evict_inode, 1230 .statfs = simple_statfs, 1231}; 1232 1233static struct file_system_type mqueue_fs_type = { 1234 .name = "mqueue", 1235 .mount = mqueue_mount, 1236 .kill_sb = kill_litter_super, 1237}; 1238 1239int mq_init_ns(struct ipc_namespace *ns) 1240{ 1241 ns->mq_queues_count = 0; 1242 ns->mq_queues_max = DFLT_QUEUESMAX; 1243 ns->mq_msg_max = DFLT_MSGMAX; 1244 ns->mq_msgsize_max = DFLT_MSGSIZEMAX; 1245 1246 ns->mq_mnt = kern_mount_data(&mqueue_fs_type, ns); 1247 if (IS_ERR(ns->mq_mnt)) { 1248 int err = PTR_ERR(ns->mq_mnt); 1249 ns->mq_mnt = NULL; 1250 return err; 1251 } 1252 return 0; 1253} 1254 1255void mq_clear_sbinfo(struct ipc_namespace *ns) 1256{ 1257 ns->mq_mnt->mnt_sb->s_fs_info = NULL; 1258} 1259 1260void mq_put_mnt(struct ipc_namespace *ns) 1261{ 1262 mntput(ns->mq_mnt); 1263} 1264 1265static int __init init_mqueue_fs(void) 1266{ 1267 int error; 1268 1269 mqueue_inode_cachep = kmem_cache_create("mqueue_inode_cache", 1270 sizeof(struct mqueue_inode_info), 0, 1271 SLAB_HWCACHE_ALIGN, init_once); 1272 if (mqueue_inode_cachep == NULL) 1273 return -ENOMEM; 1274 1275 /* ignore failures - they are not fatal */ 1276 mq_sysctl_table = mq_register_sysctl_table(); 1277 1278 error = register_filesystem(&mqueue_fs_type); 1279 if (error) 1280 goto out_sysctl; 1281 1282 spin_lock_init(&mq_lock); 1283 1284 init_ipc_ns.mq_mnt = kern_mount_data(&mqueue_fs_type, &init_ipc_ns); 1285 if (IS_ERR(init_ipc_ns.mq_mnt)) { 1286 error = PTR_ERR(init_ipc_ns.mq_mnt); 1287 goto out_filesystem; 1288 } 1289 1290 return 0; 1291 1292out_filesystem: 1293 unregister_filesystem(&mqueue_fs_type); 1294out_sysctl: 1295 if (mq_sysctl_table) 1296 unregister_sysctl_table(mq_sysctl_table); 1297 kmem_cache_destroy(mqueue_inode_cachep); 1298 return error; 1299} 1300 1301__initcall(init_mqueue_fs); 1302