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