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/user_namespace.h> 36 #include <linux/slab.h> 37 38 #include <net/sock.h> 39 #include "util.h" 40 41 #define MQUEUE_MAGIC 0x19800202 42 #define DIRENT_SIZE 20 43 #define FILENT_SIZE 80 44 45 #define SEND 0 46 #define RECV 1 47 48 #define STATE_NONE 0 49 #define STATE_PENDING 1 50 #define STATE_READY 2 51 52 struct ext_wait_queue { /* queue of sleeping tasks */ 53 struct task_struct *task; 54 struct list_head list; 55 struct msg_msg *msg; /* ptr of loaded message */ 56 int state; /* one of STATE_* values */ 57 }; 58 59 struct mqueue_inode_info { 60 spinlock_t lock; 61 struct inode vfs_inode; 62 wait_queue_head_t wait_q; 63 64 struct msg_msg **messages; 65 struct mq_attr attr; 66 67 struct sigevent notify; 68 struct pid* notify_owner; 69 struct user_struct *user; /* user who created, for accounting */ 70 struct sock *notify_sock; 71 struct sk_buff *notify_cookie; 72 73 /* for tasks waiting for free space and messages, respectively */ 74 struct ext_wait_queue e_wait_q[2]; 75 76 unsigned long qsize; /* size of queue in memory (sum of all msgs) */ 77 }; 78 79 static const struct inode_operations mqueue_dir_inode_operations; 80 static const struct file_operations mqueue_file_operations; 81 static const struct super_operations mqueue_super_ops; 82 static void remove_notification(struct mqueue_inode_info *info); 83 84 static struct kmem_cache *mqueue_inode_cachep; 85 86 static struct ctl_table_header * mq_sysctl_table; 87 88 static inline struct mqueue_inode_info *MQUEUE_I(struct inode *inode) 89 { 90 return container_of(inode, struct mqueue_inode_info, vfs_inode); 91 } 92 93 /* 94 * This routine should be called with the mq_lock held. 95 */ 96 static inline struct ipc_namespace *__get_ns_from_inode(struct inode *inode) 97 { 98 return get_ipc_ns(inode->i_sb->s_fs_info); 99 } 100 101 static struct ipc_namespace *get_ns_from_inode(struct inode *inode) 102 { 103 struct ipc_namespace *ns; 104 105 spin_lock(&mq_lock); 106 ns = __get_ns_from_inode(inode); 107 spin_unlock(&mq_lock); 108 return ns; 109 } 110 111 static struct inode *mqueue_get_inode(struct super_block *sb, 112 struct ipc_namespace *ipc_ns, umode_t mode, 113 struct mq_attr *attr) 114 { 115 struct user_struct *u = current_user(); 116 struct inode *inode; 117 int ret = -ENOMEM; 118 119 inode = new_inode(sb); 120 if (!inode) 121 goto err; 122 123 inode->i_ino = get_next_ino(); 124 inode->i_mode = mode; 125 inode->i_uid = current_fsuid(); 126 inode->i_gid = current_fsgid(); 127 inode->i_mtime = inode->i_ctime = inode->i_atime = CURRENT_TIME; 128 129 if (S_ISREG(mode)) { 130 struct mqueue_inode_info *info; 131 struct task_struct *p = current; 132 unsigned long mq_bytes, mq_msg_tblsz; 133 134 inode->i_fop = &mqueue_file_operations; 135 inode->i_size = FILENT_SIZE; 136 /* mqueue specific info */ 137 info = MQUEUE_I(inode); 138 spin_lock_init(&info->lock); 139 init_waitqueue_head(&info->wait_q); 140 INIT_LIST_HEAD(&info->e_wait_q[0].list); 141 INIT_LIST_HEAD(&info->e_wait_q[1].list); 142 info->notify_owner = NULL; 143 info->qsize = 0; 144 info->user = NULL; /* set when all is ok */ 145 memset(&info->attr, 0, sizeof(info->attr)); 146 info->attr.mq_maxmsg = ipc_ns->mq_msg_max; 147 info->attr.mq_msgsize = ipc_ns->mq_msgsize_max; 148 if (attr) { 149 info->attr.mq_maxmsg = attr->mq_maxmsg; 150 info->attr.mq_msgsize = attr->mq_msgsize; 151 } 152 mq_msg_tblsz = info->attr.mq_maxmsg * sizeof(struct msg_msg *); 153 info->messages = kmalloc(mq_msg_tblsz, GFP_KERNEL); 154 if (!info->messages) 155 goto out_inode; 156 157 mq_bytes = (mq_msg_tblsz + 158 (info->attr.mq_maxmsg * info->attr.mq_msgsize)); 159 160 spin_lock(&mq_lock); 161 if (u->mq_bytes + mq_bytes < u->mq_bytes || 162 u->mq_bytes + mq_bytes > task_rlimit(p, RLIMIT_MSGQUEUE)) { 163 spin_unlock(&mq_lock); 164 /* mqueue_evict_inode() releases info->messages */ 165 ret = -EMFILE; 166 goto out_inode; 167 } 168 u->mq_bytes += mq_bytes; 169 spin_unlock(&mq_lock); 170 171 /* all is ok */ 172 info->user = get_uid(u); 173 } else if (S_ISDIR(mode)) { 174 inc_nlink(inode); 175 /* Some things misbehave if size == 0 on a directory */ 176 inode->i_size = 2 * DIRENT_SIZE; 177 inode->i_op = &mqueue_dir_inode_operations; 178 inode->i_fop = &simple_dir_operations; 179 } 180 181 return inode; 182 out_inode: 183 iput(inode); 184 err: 185 return ERR_PTR(ret); 186 } 187 188 static int mqueue_fill_super(struct super_block *sb, void *data, int silent) 189 { 190 struct inode *inode; 191 struct ipc_namespace *ns = data; 192 int error; 193 194 sb->s_blocksize = PAGE_CACHE_SIZE; 195 sb->s_blocksize_bits = PAGE_CACHE_SHIFT; 196 sb->s_magic = MQUEUE_MAGIC; 197 sb->s_op = &mqueue_super_ops; 198 199 inode = mqueue_get_inode(sb, ns, S_IFDIR | S_ISVTX | S_IRWXUGO, 200 NULL); 201 if (IS_ERR(inode)) { 202 error = PTR_ERR(inode); 203 goto out; 204 } 205 206 sb->s_root = d_alloc_root(inode); 207 if (!sb->s_root) { 208 iput(inode); 209 error = -ENOMEM; 210 goto out; 211 } 212 error = 0; 213 214 out: 215 return error; 216 } 217 218 static struct dentry *mqueue_mount(struct file_system_type *fs_type, 219 int flags, const char *dev_name, 220 void *data) 221 { 222 if (!(flags & MS_KERNMOUNT)) 223 data = current->nsproxy->ipc_ns; 224 return mount_ns(fs_type, flags, data, mqueue_fill_super); 225 } 226 227 static void init_once(void *foo) 228 { 229 struct mqueue_inode_info *p = (struct mqueue_inode_info *) foo; 230 231 inode_init_once(&p->vfs_inode); 232 } 233 234 static struct inode *mqueue_alloc_inode(struct super_block *sb) 235 { 236 struct mqueue_inode_info *ei; 237 238 ei = kmem_cache_alloc(mqueue_inode_cachep, GFP_KERNEL); 239 if (!ei) 240 return NULL; 241 return &ei->vfs_inode; 242 } 243 244 static void mqueue_i_callback(struct rcu_head *head) 245 { 246 struct inode *inode = container_of(head, struct inode, i_rcu); 247 kmem_cache_free(mqueue_inode_cachep, MQUEUE_I(inode)); 248 } 249 250 static void mqueue_destroy_inode(struct inode *inode) 251 { 252 call_rcu(&inode->i_rcu, mqueue_i_callback); 253 } 254 255 static void mqueue_evict_inode(struct inode *inode) 256 { 257 struct mqueue_inode_info *info; 258 struct user_struct *user; 259 unsigned long mq_bytes; 260 int i; 261 struct ipc_namespace *ipc_ns; 262 263 end_writeback(inode); 264 265 if (S_ISDIR(inode->i_mode)) 266 return; 267 268 ipc_ns = get_ns_from_inode(inode); 269 info = MQUEUE_I(inode); 270 spin_lock(&info->lock); 271 for (i = 0; i < info->attr.mq_curmsgs; i++) 272 free_msg(info->messages[i]); 273 kfree(info->messages); 274 spin_unlock(&info->lock); 275 276 /* Total amount of bytes accounted for the mqueue */ 277 mq_bytes = info->attr.mq_maxmsg * (sizeof(struct msg_msg *) 278 + info->attr.mq_msgsize); 279 user = info->user; 280 if (user) { 281 spin_lock(&mq_lock); 282 user->mq_bytes -= mq_bytes; 283 /* 284 * get_ns_from_inode() ensures that the 285 * (ipc_ns = sb->s_fs_info) is either a valid ipc_ns 286 * to which we now hold a reference, or it is NULL. 287 * We can't put it here under mq_lock, though. 288 */ 289 if (ipc_ns) 290 ipc_ns->mq_queues_count--; 291 spin_unlock(&mq_lock); 292 free_uid(user); 293 } 294 if (ipc_ns) 295 put_ipc_ns(ipc_ns); 296 } 297 298 static int mqueue_create(struct inode *dir, struct dentry *dentry, 299 umode_t mode, struct nameidata *nd) 300 { 301 struct inode *inode; 302 struct mq_attr *attr = dentry->d_fsdata; 303 int error; 304 struct ipc_namespace *ipc_ns; 305 306 spin_lock(&mq_lock); 307 ipc_ns = __get_ns_from_inode(dir); 308 if (!ipc_ns) { 309 error = -EACCES; 310 goto out_unlock; 311 } 312 if (ipc_ns->mq_queues_count >= ipc_ns->mq_queues_max && 313 !capable(CAP_SYS_RESOURCE)) { 314 error = -ENOSPC; 315 goto out_unlock; 316 } 317 ipc_ns->mq_queues_count++; 318 spin_unlock(&mq_lock); 319 320 inode = mqueue_get_inode(dir->i_sb, ipc_ns, mode, attr); 321 if (IS_ERR(inode)) { 322 error = PTR_ERR(inode); 323 spin_lock(&mq_lock); 324 ipc_ns->mq_queues_count--; 325 goto out_unlock; 326 } 327 328 put_ipc_ns(ipc_ns); 329 dir->i_size += DIRENT_SIZE; 330 dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME; 331 332 d_instantiate(dentry, inode); 333 dget(dentry); 334 return 0; 335 out_unlock: 336 spin_unlock(&mq_lock); 337 if (ipc_ns) 338 put_ipc_ns(ipc_ns); 339 return error; 340 } 341 342 static int mqueue_unlink(struct inode *dir, struct dentry *dentry) 343 { 344 struct inode *inode = dentry->d_inode; 345 346 dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME; 347 dir->i_size -= DIRENT_SIZE; 348 drop_nlink(inode); 349 dput(dentry); 350 return 0; 351 } 352 353 /* 354 * This is routine for system read from queue file. 355 * To avoid mess with doing here some sort of mq_receive we allow 356 * to read only queue size & notification info (the only values 357 * that are interesting from user point of view and aren't accessible 358 * through std routines) 359 */ 360 static ssize_t mqueue_read_file(struct file *filp, char __user *u_data, 361 size_t count, loff_t *off) 362 { 363 struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode); 364 char buffer[FILENT_SIZE]; 365 ssize_t ret; 366 367 spin_lock(&info->lock); 368 snprintf(buffer, sizeof(buffer), 369 "QSIZE:%-10lu NOTIFY:%-5d SIGNO:%-5d NOTIFY_PID:%-6d\n", 370 info->qsize, 371 info->notify_owner ? info->notify.sigev_notify : 0, 372 (info->notify_owner && 373 info->notify.sigev_notify == SIGEV_SIGNAL) ? 374 info->notify.sigev_signo : 0, 375 pid_vnr(info->notify_owner)); 376 spin_unlock(&info->lock); 377 buffer[sizeof(buffer)-1] = '\0'; 378 379 ret = simple_read_from_buffer(u_data, count, off, buffer, 380 strlen(buffer)); 381 if (ret <= 0) 382 return ret; 383 384 filp->f_path.dentry->d_inode->i_atime = filp->f_path.dentry->d_inode->i_ctime = CURRENT_TIME; 385 return ret; 386 } 387 388 static int mqueue_flush_file(struct file *filp, fl_owner_t id) 389 { 390 struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode); 391 392 spin_lock(&info->lock); 393 if (task_tgid(current) == info->notify_owner) 394 remove_notification(info); 395 396 spin_unlock(&info->lock); 397 return 0; 398 } 399 400 static unsigned int mqueue_poll_file(struct file *filp, struct poll_table_struct *poll_tab) 401 { 402 struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode); 403 int retval = 0; 404 405 poll_wait(filp, &info->wait_q, poll_tab); 406 407 spin_lock(&info->lock); 408 if (info->attr.mq_curmsgs) 409 retval = POLLIN | POLLRDNORM; 410 411 if (info->attr.mq_curmsgs < info->attr.mq_maxmsg) 412 retval |= POLLOUT | POLLWRNORM; 413 spin_unlock(&info->lock); 414 415 return retval; 416 } 417 418 /* Adds current to info->e_wait_q[sr] before element with smaller prio */ 419 static void wq_add(struct mqueue_inode_info *info, int sr, 420 struct ext_wait_queue *ewp) 421 { 422 struct ext_wait_queue *walk; 423 424 ewp->task = current; 425 426 list_for_each_entry(walk, &info->e_wait_q[sr].list, list) { 427 if (walk->task->static_prio <= current->static_prio) { 428 list_add_tail(&ewp->list, &walk->list); 429 return; 430 } 431 } 432 list_add_tail(&ewp->list, &info->e_wait_q[sr].list); 433 } 434 435 /* 436 * Puts current task to sleep. Caller must hold queue lock. After return 437 * lock isn't held. 438 * sr: SEND or RECV 439 */ 440 static int wq_sleep(struct mqueue_inode_info *info, int sr, 441 ktime_t *timeout, struct ext_wait_queue *ewp) 442 { 443 int retval; 444 signed long time; 445 446 wq_add(info, sr, ewp); 447 448 for (;;) { 449 set_current_state(TASK_INTERRUPTIBLE); 450 451 spin_unlock(&info->lock); 452 time = schedule_hrtimeout_range_clock(timeout, 0, 453 HRTIMER_MODE_ABS, CLOCK_REALTIME); 454 455 while (ewp->state == STATE_PENDING) 456 cpu_relax(); 457 458 if (ewp->state == STATE_READY) { 459 retval = 0; 460 goto out; 461 } 462 spin_lock(&info->lock); 463 if (ewp->state == STATE_READY) { 464 retval = 0; 465 goto out_unlock; 466 } 467 if (signal_pending(current)) { 468 retval = -ERESTARTSYS; 469 break; 470 } 471 if (time == 0) { 472 retval = -ETIMEDOUT; 473 break; 474 } 475 } 476 list_del(&ewp->list); 477 out_unlock: 478 spin_unlock(&info->lock); 479 out: 480 return retval; 481 } 482 483 /* 484 * Returns waiting task that should be serviced first or NULL if none exists 485 */ 486 static struct ext_wait_queue *wq_get_first_waiter( 487 struct mqueue_inode_info *info, int sr) 488 { 489 struct list_head *ptr; 490 491 ptr = info->e_wait_q[sr].list.prev; 492 if (ptr == &info->e_wait_q[sr].list) 493 return NULL; 494 return list_entry(ptr, struct ext_wait_queue, list); 495 } 496 497 /* Auxiliary functions to manipulate messages' list */ 498 static void msg_insert(struct msg_msg *ptr, struct mqueue_inode_info *info) 499 { 500 int k; 501 502 k = info->attr.mq_curmsgs - 1; 503 while (k >= 0 && info->messages[k]->m_type >= ptr->m_type) { 504 info->messages[k + 1] = info->messages[k]; 505 k--; 506 } 507 info->attr.mq_curmsgs++; 508 info->qsize += ptr->m_ts; 509 info->messages[k + 1] = ptr; 510 } 511 512 static inline struct msg_msg *msg_get(struct mqueue_inode_info *info) 513 { 514 info->qsize -= info->messages[--info->attr.mq_curmsgs]->m_ts; 515 return info->messages[info->attr.mq_curmsgs]; 516 } 517 518 static inline void set_cookie(struct sk_buff *skb, char code) 519 { 520 ((char*)skb->data)[NOTIFY_COOKIE_LEN-1] = code; 521 } 522 523 /* 524 * The next function is only to split too long sys_mq_timedsend 525 */ 526 static void __do_notify(struct mqueue_inode_info *info) 527 { 528 /* notification 529 * invoked when there is registered process and there isn't process 530 * waiting synchronously for message AND state of queue changed from 531 * empty to not empty. Here we are sure that no one is waiting 532 * synchronously. */ 533 if (info->notify_owner && 534 info->attr.mq_curmsgs == 1) { 535 struct siginfo sig_i; 536 switch (info->notify.sigev_notify) { 537 case SIGEV_NONE: 538 break; 539 case SIGEV_SIGNAL: 540 /* sends signal */ 541 542 sig_i.si_signo = info->notify.sigev_signo; 543 sig_i.si_errno = 0; 544 sig_i.si_code = SI_MESGQ; 545 sig_i.si_value = info->notify.sigev_value; 546 /* map current pid/uid into info->owner's namespaces */ 547 rcu_read_lock(); 548 sig_i.si_pid = task_tgid_nr_ns(current, 549 ns_of_pid(info->notify_owner)); 550 sig_i.si_uid = user_ns_map_uid(info->user->user_ns, 551 current_cred(), current_uid()); 552 rcu_read_unlock(); 553 554 kill_pid_info(info->notify.sigev_signo, 555 &sig_i, info->notify_owner); 556 break; 557 case SIGEV_THREAD: 558 set_cookie(info->notify_cookie, NOTIFY_WOKENUP); 559 netlink_sendskb(info->notify_sock, info->notify_cookie); 560 break; 561 } 562 /* after notification unregisters process */ 563 put_pid(info->notify_owner); 564 info->notify_owner = NULL; 565 } 566 wake_up(&info->wait_q); 567 } 568 569 static int prepare_timeout(const struct timespec __user *u_abs_timeout, 570 ktime_t *expires, struct timespec *ts) 571 { 572 if (copy_from_user(ts, u_abs_timeout, sizeof(struct timespec))) 573 return -EFAULT; 574 if (!timespec_valid(ts)) 575 return -EINVAL; 576 577 *expires = timespec_to_ktime(*ts); 578 return 0; 579 } 580 581 static void remove_notification(struct mqueue_inode_info *info) 582 { 583 if (info->notify_owner != NULL && 584 info->notify.sigev_notify == SIGEV_THREAD) { 585 set_cookie(info->notify_cookie, NOTIFY_REMOVED); 586 netlink_sendskb(info->notify_sock, info->notify_cookie); 587 } 588 put_pid(info->notify_owner); 589 info->notify_owner = NULL; 590 } 591 592 static int mq_attr_ok(struct ipc_namespace *ipc_ns, struct mq_attr *attr) 593 { 594 if (attr->mq_maxmsg <= 0 || attr->mq_msgsize <= 0) 595 return 0; 596 if (capable(CAP_SYS_RESOURCE)) { 597 if (attr->mq_maxmsg > HARD_MSGMAX) 598 return 0; 599 } else { 600 if (attr->mq_maxmsg > ipc_ns->mq_msg_max || 601 attr->mq_msgsize > ipc_ns->mq_msgsize_max) 602 return 0; 603 } 604 /* check for overflow */ 605 if (attr->mq_msgsize > ULONG_MAX/attr->mq_maxmsg) 606 return 0; 607 if ((unsigned long)(attr->mq_maxmsg * (attr->mq_msgsize 608 + sizeof (struct msg_msg *))) < 609 (unsigned long)(attr->mq_maxmsg * attr->mq_msgsize)) 610 return 0; 611 return 1; 612 } 613 614 /* 615 * Invoked when creating a new queue via sys_mq_open 616 */ 617 static struct file *do_create(struct ipc_namespace *ipc_ns, struct dentry *dir, 618 struct dentry *dentry, int oflag, umode_t mode, 619 struct mq_attr *attr) 620 { 621 const struct cred *cred = current_cred(); 622 struct file *result; 623 int ret; 624 625 if (attr) { 626 if (!mq_attr_ok(ipc_ns, attr)) { 627 ret = -EINVAL; 628 goto out; 629 } 630 /* store for use during create */ 631 dentry->d_fsdata = attr; 632 } 633 634 mode &= ~current_umask(); 635 ret = mnt_want_write(ipc_ns->mq_mnt); 636 if (ret) 637 goto out; 638 ret = vfs_create(dir->d_inode, dentry, mode, NULL); 639 dentry->d_fsdata = NULL; 640 if (ret) 641 goto out_drop_write; 642 643 result = dentry_open(dentry, ipc_ns->mq_mnt, oflag, cred); 644 /* 645 * dentry_open() took a persistent mnt_want_write(), 646 * so we can now drop this one. 647 */ 648 mnt_drop_write(ipc_ns->mq_mnt); 649 return result; 650 651 out_drop_write: 652 mnt_drop_write(ipc_ns->mq_mnt); 653 out: 654 dput(dentry); 655 mntput(ipc_ns->mq_mnt); 656 return ERR_PTR(ret); 657 } 658 659 /* Opens existing queue */ 660 static struct file *do_open(struct ipc_namespace *ipc_ns, 661 struct dentry *dentry, int oflag) 662 { 663 int ret; 664 const struct cred *cred = current_cred(); 665 666 static const int oflag2acc[O_ACCMODE] = { MAY_READ, MAY_WRITE, 667 MAY_READ | MAY_WRITE }; 668 669 if ((oflag & O_ACCMODE) == (O_RDWR | O_WRONLY)) { 670 ret = -EINVAL; 671 goto err; 672 } 673 674 if (inode_permission(dentry->d_inode, oflag2acc[oflag & O_ACCMODE])) { 675 ret = -EACCES; 676 goto err; 677 } 678 679 return dentry_open(dentry, ipc_ns->mq_mnt, oflag, cred); 680 681 err: 682 dput(dentry); 683 mntput(ipc_ns->mq_mnt); 684 return ERR_PTR(ret); 685 } 686 687 SYSCALL_DEFINE4(mq_open, const char __user *, u_name, int, oflag, umode_t, mode, 688 struct mq_attr __user *, u_attr) 689 { 690 struct dentry *dentry; 691 struct file *filp; 692 char *name; 693 struct mq_attr attr; 694 int fd, error; 695 struct ipc_namespace *ipc_ns = current->nsproxy->ipc_ns; 696 697 if (u_attr && copy_from_user(&attr, u_attr, sizeof(struct mq_attr))) 698 return -EFAULT; 699 700 audit_mq_open(oflag, mode, u_attr ? &attr : NULL); 701 702 if (IS_ERR(name = getname(u_name))) 703 return PTR_ERR(name); 704 705 fd = get_unused_fd_flags(O_CLOEXEC); 706 if (fd < 0) 707 goto out_putname; 708 709 mutex_lock(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex); 710 dentry = lookup_one_len(name, ipc_ns->mq_mnt->mnt_root, strlen(name)); 711 if (IS_ERR(dentry)) { 712 error = PTR_ERR(dentry); 713 goto out_putfd; 714 } 715 mntget(ipc_ns->mq_mnt); 716 717 if (oflag & O_CREAT) { 718 if (dentry->d_inode) { /* entry already exists */ 719 audit_inode(name, dentry); 720 if (oflag & O_EXCL) { 721 error = -EEXIST; 722 goto out; 723 } 724 filp = do_open(ipc_ns, dentry, oflag); 725 } else { 726 filp = do_create(ipc_ns, ipc_ns->mq_mnt->mnt_root, 727 dentry, oflag, mode, 728 u_attr ? &attr : NULL); 729 } 730 } else { 731 if (!dentry->d_inode) { 732 error = -ENOENT; 733 goto out; 734 } 735 audit_inode(name, dentry); 736 filp = do_open(ipc_ns, dentry, oflag); 737 } 738 739 if (IS_ERR(filp)) { 740 error = PTR_ERR(filp); 741 goto out_putfd; 742 } 743 744 fd_install(fd, filp); 745 goto out_upsem; 746 747 out: 748 dput(dentry); 749 mntput(ipc_ns->mq_mnt); 750 out_putfd: 751 put_unused_fd(fd); 752 fd = error; 753 out_upsem: 754 mutex_unlock(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex); 755 out_putname: 756 putname(name); 757 return fd; 758 } 759 760 SYSCALL_DEFINE1(mq_unlink, const char __user *, u_name) 761 { 762 int err; 763 char *name; 764 struct dentry *dentry; 765 struct inode *inode = NULL; 766 struct ipc_namespace *ipc_ns = current->nsproxy->ipc_ns; 767 768 name = getname(u_name); 769 if (IS_ERR(name)) 770 return PTR_ERR(name); 771 772 mutex_lock_nested(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex, 773 I_MUTEX_PARENT); 774 dentry = lookup_one_len(name, ipc_ns->mq_mnt->mnt_root, strlen(name)); 775 if (IS_ERR(dentry)) { 776 err = PTR_ERR(dentry); 777 goto out_unlock; 778 } 779 780 if (!dentry->d_inode) { 781 err = -ENOENT; 782 goto out_err; 783 } 784 785 inode = dentry->d_inode; 786 if (inode) 787 ihold(inode); 788 err = mnt_want_write(ipc_ns->mq_mnt); 789 if (err) 790 goto out_err; 791 err = vfs_unlink(dentry->d_parent->d_inode, dentry); 792 mnt_drop_write(ipc_ns->mq_mnt); 793 out_err: 794 dput(dentry); 795 796 out_unlock: 797 mutex_unlock(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex); 798 putname(name); 799 if (inode) 800 iput(inode); 801 802 return err; 803 } 804 805 /* Pipelined send and receive functions. 806 * 807 * If a receiver finds no waiting message, then it registers itself in the 808 * list of waiting receivers. A sender checks that list before adding the new 809 * message into the message array. If there is a waiting receiver, then it 810 * bypasses the message array and directly hands the message over to the 811 * receiver. 812 * The receiver accepts the message and returns without grabbing the queue 813 * spinlock. Therefore an intermediate STATE_PENDING state and memory barriers 814 * are necessary. The same algorithm is used for sysv semaphores, see 815 * ipc/sem.c for more details. 816 * 817 * The same algorithm is used for senders. 818 */ 819 820 /* pipelined_send() - send a message directly to the task waiting in 821 * sys_mq_timedreceive() (without inserting message into a queue). 822 */ 823 static inline void pipelined_send(struct mqueue_inode_info *info, 824 struct msg_msg *message, 825 struct ext_wait_queue *receiver) 826 { 827 receiver->msg = message; 828 list_del(&receiver->list); 829 receiver->state = STATE_PENDING; 830 wake_up_process(receiver->task); 831 smp_wmb(); 832 receiver->state = STATE_READY; 833 } 834 835 /* pipelined_receive() - if there is task waiting in sys_mq_timedsend() 836 * gets its message and put to the queue (we have one free place for sure). */ 837 static inline void pipelined_receive(struct mqueue_inode_info *info) 838 { 839 struct ext_wait_queue *sender = wq_get_first_waiter(info, SEND); 840 841 if (!sender) { 842 /* for poll */ 843 wake_up_interruptible(&info->wait_q); 844 return; 845 } 846 msg_insert(sender->msg, info); 847 list_del(&sender->list); 848 sender->state = STATE_PENDING; 849 wake_up_process(sender->task); 850 smp_wmb(); 851 sender->state = STATE_READY; 852 } 853 854 SYSCALL_DEFINE5(mq_timedsend, mqd_t, mqdes, const char __user *, u_msg_ptr, 855 size_t, msg_len, unsigned int, msg_prio, 856 const struct timespec __user *, u_abs_timeout) 857 { 858 struct file *filp; 859 struct inode *inode; 860 struct ext_wait_queue wait; 861 struct ext_wait_queue *receiver; 862 struct msg_msg *msg_ptr; 863 struct mqueue_inode_info *info; 864 ktime_t expires, *timeout = NULL; 865 struct timespec ts; 866 int ret; 867 868 if (u_abs_timeout) { 869 int res = prepare_timeout(u_abs_timeout, &expires, &ts); 870 if (res) 871 return res; 872 timeout = &expires; 873 } 874 875 if (unlikely(msg_prio >= (unsigned long) MQ_PRIO_MAX)) 876 return -EINVAL; 877 878 audit_mq_sendrecv(mqdes, msg_len, msg_prio, timeout ? &ts : NULL); 879 880 filp = fget(mqdes); 881 if (unlikely(!filp)) { 882 ret = -EBADF; 883 goto out; 884 } 885 886 inode = filp->f_path.dentry->d_inode; 887 if (unlikely(filp->f_op != &mqueue_file_operations)) { 888 ret = -EBADF; 889 goto out_fput; 890 } 891 info = MQUEUE_I(inode); 892 audit_inode(NULL, filp->f_path.dentry); 893 894 if (unlikely(!(filp->f_mode & FMODE_WRITE))) { 895 ret = -EBADF; 896 goto out_fput; 897 } 898 899 if (unlikely(msg_len > info->attr.mq_msgsize)) { 900 ret = -EMSGSIZE; 901 goto out_fput; 902 } 903 904 /* First try to allocate memory, before doing anything with 905 * existing queues. */ 906 msg_ptr = load_msg(u_msg_ptr, msg_len); 907 if (IS_ERR(msg_ptr)) { 908 ret = PTR_ERR(msg_ptr); 909 goto out_fput; 910 } 911 msg_ptr->m_ts = msg_len; 912 msg_ptr->m_type = msg_prio; 913 914 spin_lock(&info->lock); 915 916 if (info->attr.mq_curmsgs == info->attr.mq_maxmsg) { 917 if (filp->f_flags & O_NONBLOCK) { 918 spin_unlock(&info->lock); 919 ret = -EAGAIN; 920 } else { 921 wait.task = current; 922 wait.msg = (void *) msg_ptr; 923 wait.state = STATE_NONE; 924 ret = wq_sleep(info, SEND, timeout, &wait); 925 } 926 if (ret < 0) 927 free_msg(msg_ptr); 928 } else { 929 receiver = wq_get_first_waiter(info, RECV); 930 if (receiver) { 931 pipelined_send(info, msg_ptr, receiver); 932 } else { 933 /* adds message to the queue */ 934 msg_insert(msg_ptr, info); 935 __do_notify(info); 936 } 937 inode->i_atime = inode->i_mtime = inode->i_ctime = 938 CURRENT_TIME; 939 spin_unlock(&info->lock); 940 ret = 0; 941 } 942 out_fput: 943 fput(filp); 944 out: 945 return ret; 946 } 947 948 SYSCALL_DEFINE5(mq_timedreceive, mqd_t, mqdes, char __user *, u_msg_ptr, 949 size_t, msg_len, unsigned int __user *, u_msg_prio, 950 const struct timespec __user *, u_abs_timeout) 951 { 952 ssize_t ret; 953 struct msg_msg *msg_ptr; 954 struct file *filp; 955 struct inode *inode; 956 struct mqueue_inode_info *info; 957 struct ext_wait_queue wait; 958 ktime_t expires, *timeout = NULL; 959 struct timespec ts; 960 961 if (u_abs_timeout) { 962 int res = prepare_timeout(u_abs_timeout, &expires, &ts); 963 if (res) 964 return res; 965 timeout = &expires; 966 } 967 968 audit_mq_sendrecv(mqdes, msg_len, 0, timeout ? &ts : NULL); 969 970 filp = fget(mqdes); 971 if (unlikely(!filp)) { 972 ret = -EBADF; 973 goto out; 974 } 975 976 inode = filp->f_path.dentry->d_inode; 977 if (unlikely(filp->f_op != &mqueue_file_operations)) { 978 ret = -EBADF; 979 goto out_fput; 980 } 981 info = MQUEUE_I(inode); 982 audit_inode(NULL, filp->f_path.dentry); 983 984 if (unlikely(!(filp->f_mode & FMODE_READ))) { 985 ret = -EBADF; 986 goto out_fput; 987 } 988 989 /* checks if buffer is big enough */ 990 if (unlikely(msg_len < info->attr.mq_msgsize)) { 991 ret = -EMSGSIZE; 992 goto out_fput; 993 } 994 995 spin_lock(&info->lock); 996 if (info->attr.mq_curmsgs == 0) { 997 if (filp->f_flags & O_NONBLOCK) { 998 spin_unlock(&info->lock); 999 ret = -EAGAIN; 1000 } else { 1001 wait.task = current; 1002 wait.state = STATE_NONE; 1003 ret = wq_sleep(info, RECV, timeout, &wait); 1004 msg_ptr = wait.msg; 1005 } 1006 } else { 1007 msg_ptr = msg_get(info); 1008 1009 inode->i_atime = inode->i_mtime = inode->i_ctime = 1010 CURRENT_TIME; 1011 1012 /* There is now free space in queue. */ 1013 pipelined_receive(info); 1014 spin_unlock(&info->lock); 1015 ret = 0; 1016 } 1017 if (ret == 0) { 1018 ret = msg_ptr->m_ts; 1019 1020 if ((u_msg_prio && put_user(msg_ptr->m_type, u_msg_prio)) || 1021 store_msg(u_msg_ptr, msg_ptr, msg_ptr->m_ts)) { 1022 ret = -EFAULT; 1023 } 1024 free_msg(msg_ptr); 1025 } 1026 out_fput: 1027 fput(filp); 1028 out: 1029 return ret; 1030 } 1031 1032 /* 1033 * Notes: the case when user wants us to deregister (with NULL as pointer) 1034 * and he isn't currently owner of notification, will be silently discarded. 1035 * It isn't explicitly defined in the POSIX. 1036 */ 1037 SYSCALL_DEFINE2(mq_notify, mqd_t, mqdes, 1038 const struct sigevent __user *, u_notification) 1039 { 1040 int ret; 1041 struct file *filp; 1042 struct sock *sock; 1043 struct inode *inode; 1044 struct sigevent notification; 1045 struct mqueue_inode_info *info; 1046 struct sk_buff *nc; 1047 1048 if (u_notification) { 1049 if (copy_from_user(¬ification, u_notification, 1050 sizeof(struct sigevent))) 1051 return -EFAULT; 1052 } 1053 1054 audit_mq_notify(mqdes, u_notification ? ¬ification : NULL); 1055 1056 nc = NULL; 1057 sock = NULL; 1058 if (u_notification != NULL) { 1059 if (unlikely(notification.sigev_notify != SIGEV_NONE && 1060 notification.sigev_notify != SIGEV_SIGNAL && 1061 notification.sigev_notify != SIGEV_THREAD)) 1062 return -EINVAL; 1063 if (notification.sigev_notify == SIGEV_SIGNAL && 1064 !valid_signal(notification.sigev_signo)) { 1065 return -EINVAL; 1066 } 1067 if (notification.sigev_notify == SIGEV_THREAD) { 1068 long timeo; 1069 1070 /* create the notify skb */ 1071 nc = alloc_skb(NOTIFY_COOKIE_LEN, GFP_KERNEL); 1072 if (!nc) { 1073 ret = -ENOMEM; 1074 goto out; 1075 } 1076 if (copy_from_user(nc->data, 1077 notification.sigev_value.sival_ptr, 1078 NOTIFY_COOKIE_LEN)) { 1079 ret = -EFAULT; 1080 goto out; 1081 } 1082 1083 /* TODO: add a header? */ 1084 skb_put(nc, NOTIFY_COOKIE_LEN); 1085 /* and attach it to the socket */ 1086 retry: 1087 filp = fget(notification.sigev_signo); 1088 if (!filp) { 1089 ret = -EBADF; 1090 goto out; 1091 } 1092 sock = netlink_getsockbyfilp(filp); 1093 fput(filp); 1094 if (IS_ERR(sock)) { 1095 ret = PTR_ERR(sock); 1096 sock = NULL; 1097 goto out; 1098 } 1099 1100 timeo = MAX_SCHEDULE_TIMEOUT; 1101 ret = netlink_attachskb(sock, nc, &timeo, NULL); 1102 if (ret == 1) 1103 goto retry; 1104 if (ret) { 1105 sock = NULL; 1106 nc = NULL; 1107 goto out; 1108 } 1109 } 1110 } 1111 1112 filp = fget(mqdes); 1113 if (!filp) { 1114 ret = -EBADF; 1115 goto out; 1116 } 1117 1118 inode = filp->f_path.dentry->d_inode; 1119 if (unlikely(filp->f_op != &mqueue_file_operations)) { 1120 ret = -EBADF; 1121 goto out_fput; 1122 } 1123 info = MQUEUE_I(inode); 1124 1125 ret = 0; 1126 spin_lock(&info->lock); 1127 if (u_notification == NULL) { 1128 if (info->notify_owner == task_tgid(current)) { 1129 remove_notification(info); 1130 inode->i_atime = inode->i_ctime = CURRENT_TIME; 1131 } 1132 } else if (info->notify_owner != NULL) { 1133 ret = -EBUSY; 1134 } else { 1135 switch (notification.sigev_notify) { 1136 case SIGEV_NONE: 1137 info->notify.sigev_notify = SIGEV_NONE; 1138 break; 1139 case SIGEV_THREAD: 1140 info->notify_sock = sock; 1141 info->notify_cookie = nc; 1142 sock = NULL; 1143 nc = NULL; 1144 info->notify.sigev_notify = SIGEV_THREAD; 1145 break; 1146 case SIGEV_SIGNAL: 1147 info->notify.sigev_signo = notification.sigev_signo; 1148 info->notify.sigev_value = notification.sigev_value; 1149 info->notify.sigev_notify = SIGEV_SIGNAL; 1150 break; 1151 } 1152 1153 info->notify_owner = get_pid(task_tgid(current)); 1154 inode->i_atime = inode->i_ctime = CURRENT_TIME; 1155 } 1156 spin_unlock(&info->lock); 1157 out_fput: 1158 fput(filp); 1159 out: 1160 if (sock) { 1161 netlink_detachskb(sock, nc); 1162 } else if (nc) { 1163 dev_kfree_skb(nc); 1164 } 1165 return ret; 1166 } 1167 1168 SYSCALL_DEFINE3(mq_getsetattr, mqd_t, mqdes, 1169 const struct mq_attr __user *, u_mqstat, 1170 struct mq_attr __user *, u_omqstat) 1171 { 1172 int ret; 1173 struct mq_attr mqstat, omqstat; 1174 struct file *filp; 1175 struct inode *inode; 1176 struct mqueue_inode_info *info; 1177 1178 if (u_mqstat != NULL) { 1179 if (copy_from_user(&mqstat, u_mqstat, sizeof(struct mq_attr))) 1180 return -EFAULT; 1181 if (mqstat.mq_flags & (~O_NONBLOCK)) 1182 return -EINVAL; 1183 } 1184 1185 filp = fget(mqdes); 1186 if (!filp) { 1187 ret = -EBADF; 1188 goto out; 1189 } 1190 1191 inode = filp->f_path.dentry->d_inode; 1192 if (unlikely(filp->f_op != &mqueue_file_operations)) { 1193 ret = -EBADF; 1194 goto out_fput; 1195 } 1196 info = MQUEUE_I(inode); 1197 1198 spin_lock(&info->lock); 1199 1200 omqstat = info->attr; 1201 omqstat.mq_flags = filp->f_flags & O_NONBLOCK; 1202 if (u_mqstat) { 1203 audit_mq_getsetattr(mqdes, &mqstat); 1204 spin_lock(&filp->f_lock); 1205 if (mqstat.mq_flags & O_NONBLOCK) 1206 filp->f_flags |= O_NONBLOCK; 1207 else 1208 filp->f_flags &= ~O_NONBLOCK; 1209 spin_unlock(&filp->f_lock); 1210 1211 inode->i_atime = inode->i_ctime = CURRENT_TIME; 1212 } 1213 1214 spin_unlock(&info->lock); 1215 1216 ret = 0; 1217 if (u_omqstat != NULL && copy_to_user(u_omqstat, &omqstat, 1218 sizeof(struct mq_attr))) 1219 ret = -EFAULT; 1220 1221 out_fput: 1222 fput(filp); 1223 out: 1224 return ret; 1225 } 1226 1227 static const struct inode_operations mqueue_dir_inode_operations = { 1228 .lookup = simple_lookup, 1229 .create = mqueue_create, 1230 .unlink = mqueue_unlink, 1231 }; 1232 1233 static const struct file_operations mqueue_file_operations = { 1234 .flush = mqueue_flush_file, 1235 .poll = mqueue_poll_file, 1236 .read = mqueue_read_file, 1237 .llseek = default_llseek, 1238 }; 1239 1240 static const struct super_operations mqueue_super_ops = { 1241 .alloc_inode = mqueue_alloc_inode, 1242 .destroy_inode = mqueue_destroy_inode, 1243 .evict_inode = mqueue_evict_inode, 1244 .statfs = simple_statfs, 1245 }; 1246 1247 static struct file_system_type mqueue_fs_type = { 1248 .name = "mqueue", 1249 .mount = mqueue_mount, 1250 .kill_sb = kill_litter_super, 1251 }; 1252 1253 int mq_init_ns(struct ipc_namespace *ns) 1254 { 1255 ns->mq_queues_count = 0; 1256 ns->mq_queues_max = DFLT_QUEUESMAX; 1257 ns->mq_msg_max = DFLT_MSGMAX; 1258 ns->mq_msgsize_max = DFLT_MSGSIZEMAX; 1259 1260 ns->mq_mnt = kern_mount_data(&mqueue_fs_type, ns); 1261 if (IS_ERR(ns->mq_mnt)) { 1262 int err = PTR_ERR(ns->mq_mnt); 1263 ns->mq_mnt = NULL; 1264 return err; 1265 } 1266 return 0; 1267 } 1268 1269 void mq_clear_sbinfo(struct ipc_namespace *ns) 1270 { 1271 ns->mq_mnt->mnt_sb->s_fs_info = NULL; 1272 } 1273 1274 void mq_put_mnt(struct ipc_namespace *ns) 1275 { 1276 kern_unmount(ns->mq_mnt); 1277 } 1278 1279 static int __init init_mqueue_fs(void) 1280 { 1281 int error; 1282 1283 mqueue_inode_cachep = kmem_cache_create("mqueue_inode_cache", 1284 sizeof(struct mqueue_inode_info), 0, 1285 SLAB_HWCACHE_ALIGN, init_once); 1286 if (mqueue_inode_cachep == NULL) 1287 return -ENOMEM; 1288 1289 /* ignore failures - they are not fatal */ 1290 mq_sysctl_table = mq_register_sysctl_table(); 1291 1292 error = register_filesystem(&mqueue_fs_type); 1293 if (error) 1294 goto out_sysctl; 1295 1296 spin_lock_init(&mq_lock); 1297 1298 error = mq_init_ns(&init_ipc_ns); 1299 if (error) 1300 goto out_filesystem; 1301 1302 return 0; 1303 1304 out_filesystem: 1305 unregister_filesystem(&mqueue_fs_type); 1306 out_sysctl: 1307 if (mq_sysctl_table) 1308 unregister_sysctl_table(mq_sysctl_table); 1309 kmem_cache_destroy(mqueue_inode_cachep); 1310 return error; 1311 } 1312 1313 __initcall(init_mqueue_fs); 1314