1 /* 2 * POSIX message queues filesystem for Linux. 3 * 4 * Copyright (C) 2003,2004 Krzysztof Benedyczak ([email protected]) 5 * Michal Wronski ([email protected]) 6 * 7 * Spinlocks: Mohamed Abbas ([email protected]) 8 * Lockless receive & send, fd based notify: 9 * Manfred Spraul ([email protected]) 10 * 11 * Audit: George Wilson ([email protected]) 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_namespace *notify_user_ns; 70 struct user_struct *user; /* user who created, for accounting */ 71 struct sock *notify_sock; 72 struct sk_buff *notify_cookie; 73 74 /* for tasks waiting for free space and messages, respectively */ 75 struct ext_wait_queue e_wait_q[2]; 76 77 unsigned long qsize; /* size of queue in memory (sum of all msgs) */ 78 }; 79 80 static const struct inode_operations mqueue_dir_inode_operations; 81 static const struct file_operations mqueue_file_operations; 82 static const struct super_operations mqueue_super_ops; 83 static void remove_notification(struct mqueue_inode_info *info); 84 85 static struct kmem_cache *mqueue_inode_cachep; 86 87 static struct ctl_table_header * mq_sysctl_table; 88 89 static inline struct mqueue_inode_info *MQUEUE_I(struct inode *inode) 90 { 91 return container_of(inode, struct mqueue_inode_info, vfs_inode); 92 } 93 94 /* 95 * This routine should be called with the mq_lock held. 96 */ 97 static inline struct ipc_namespace *__get_ns_from_inode(struct inode *inode) 98 { 99 return get_ipc_ns(inode->i_sb->s_fs_info); 100 } 101 102 static struct ipc_namespace *get_ns_from_inode(struct inode *inode) 103 { 104 struct ipc_namespace *ns; 105 106 spin_lock(&mq_lock); 107 ns = __get_ns_from_inode(inode); 108 spin_unlock(&mq_lock); 109 return ns; 110 } 111 112 static struct inode *mqueue_get_inode(struct super_block *sb, 113 struct ipc_namespace *ipc_ns, umode_t mode, 114 struct mq_attr *attr) 115 { 116 struct user_struct *u = current_user(); 117 struct inode *inode; 118 int ret = -ENOMEM; 119 120 inode = new_inode(sb); 121 if (!inode) 122 goto err; 123 124 inode->i_ino = get_next_ino(); 125 inode->i_mode = mode; 126 inode->i_uid = current_fsuid(); 127 inode->i_gid = current_fsgid(); 128 inode->i_mtime = inode->i_ctime = inode->i_atime = CURRENT_TIME; 129 130 if (S_ISREG(mode)) { 131 struct mqueue_inode_info *info; 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->notify_user_ns = NULL; 144 info->qsize = 0; 145 info->user = NULL; /* set when all is ok */ 146 memset(&info->attr, 0, sizeof(info->attr)); 147 info->attr.mq_maxmsg = ipc_ns->mq_msg_max; 148 info->attr.mq_msgsize = ipc_ns->mq_msgsize_max; 149 if (attr) { 150 info->attr.mq_maxmsg = attr->mq_maxmsg; 151 info->attr.mq_msgsize = attr->mq_msgsize; 152 } 153 mq_msg_tblsz = info->attr.mq_maxmsg * sizeof(struct msg_msg *); 154 info->messages = kmalloc(mq_msg_tblsz, GFP_KERNEL); 155 if (!info->messages) 156 goto out_inode; 157 158 mq_bytes = (mq_msg_tblsz + 159 (info->attr.mq_maxmsg * info->attr.mq_msgsize)); 160 161 spin_lock(&mq_lock); 162 if (u->mq_bytes + mq_bytes < u->mq_bytes || 163 u->mq_bytes + mq_bytes > rlimit(RLIMIT_MSGQUEUE)) { 164 spin_unlock(&mq_lock); 165 /* mqueue_evict_inode() releases info->messages */ 166 ret = -EMFILE; 167 goto out_inode; 168 } 169 u->mq_bytes += mq_bytes; 170 spin_unlock(&mq_lock); 171 172 /* all is ok */ 173 info->user = get_uid(u); 174 } else if (S_ISDIR(mode)) { 175 inc_nlink(inode); 176 /* Some things misbehave if size == 0 on a directory */ 177 inode->i_size = 2 * DIRENT_SIZE; 178 inode->i_op = &mqueue_dir_inode_operations; 179 inode->i_fop = &simple_dir_operations; 180 } 181 182 return inode; 183 out_inode: 184 iput(inode); 185 err: 186 return ERR_PTR(ret); 187 } 188 189 static int mqueue_fill_super(struct super_block *sb, void *data, int silent) 190 { 191 struct inode *inode; 192 struct ipc_namespace *ns = data; 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, NULL); 200 if (IS_ERR(inode)) 201 return PTR_ERR(inode); 202 203 sb->s_root = d_make_root(inode); 204 if (!sb->s_root) 205 return -ENOMEM; 206 return 0; 207 } 208 209 static struct dentry *mqueue_mount(struct file_system_type *fs_type, 210 int flags, const char *dev_name, 211 void *data) 212 { 213 if (!(flags & MS_KERNMOUNT)) 214 data = current->nsproxy->ipc_ns; 215 return mount_ns(fs_type, flags, data, mqueue_fill_super); 216 } 217 218 static void init_once(void *foo) 219 { 220 struct mqueue_inode_info *p = (struct mqueue_inode_info *) foo; 221 222 inode_init_once(&p->vfs_inode); 223 } 224 225 static struct inode *mqueue_alloc_inode(struct super_block *sb) 226 { 227 struct mqueue_inode_info *ei; 228 229 ei = kmem_cache_alloc(mqueue_inode_cachep, GFP_KERNEL); 230 if (!ei) 231 return NULL; 232 return &ei->vfs_inode; 233 } 234 235 static void mqueue_i_callback(struct rcu_head *head) 236 { 237 struct inode *inode = container_of(head, struct inode, i_rcu); 238 kmem_cache_free(mqueue_inode_cachep, MQUEUE_I(inode)); 239 } 240 241 static void mqueue_destroy_inode(struct inode *inode) 242 { 243 call_rcu(&inode->i_rcu, mqueue_i_callback); 244 } 245 246 static void mqueue_evict_inode(struct inode *inode) 247 { 248 struct mqueue_inode_info *info; 249 struct user_struct *user; 250 unsigned long mq_bytes; 251 int i; 252 struct ipc_namespace *ipc_ns; 253 254 end_writeback(inode); 255 256 if (S_ISDIR(inode->i_mode)) 257 return; 258 259 ipc_ns = get_ns_from_inode(inode); 260 info = MQUEUE_I(inode); 261 spin_lock(&info->lock); 262 for (i = 0; i < info->attr.mq_curmsgs; i++) 263 free_msg(info->messages[i]); 264 kfree(info->messages); 265 spin_unlock(&info->lock); 266 267 /* Total amount of bytes accounted for the mqueue */ 268 mq_bytes = info->attr.mq_maxmsg * (sizeof(struct msg_msg *) 269 + info->attr.mq_msgsize); 270 user = info->user; 271 if (user) { 272 spin_lock(&mq_lock); 273 user->mq_bytes -= mq_bytes; 274 /* 275 * get_ns_from_inode() ensures that the 276 * (ipc_ns = sb->s_fs_info) is either a valid ipc_ns 277 * to which we now hold a reference, or it is NULL. 278 * We can't put it here under mq_lock, though. 279 */ 280 if (ipc_ns) 281 ipc_ns->mq_queues_count--; 282 spin_unlock(&mq_lock); 283 free_uid(user); 284 } 285 if (ipc_ns) 286 put_ipc_ns(ipc_ns); 287 } 288 289 static int mqueue_create(struct inode *dir, struct dentry *dentry, 290 umode_t mode, struct nameidata *nd) 291 { 292 struct inode *inode; 293 struct mq_attr *attr = dentry->d_fsdata; 294 int error; 295 struct ipc_namespace *ipc_ns; 296 297 spin_lock(&mq_lock); 298 ipc_ns = __get_ns_from_inode(dir); 299 if (!ipc_ns) { 300 error = -EACCES; 301 goto out_unlock; 302 } 303 if (ipc_ns->mq_queues_count >= ipc_ns->mq_queues_max && 304 !capable(CAP_SYS_RESOURCE)) { 305 error = -ENOSPC; 306 goto out_unlock; 307 } 308 ipc_ns->mq_queues_count++; 309 spin_unlock(&mq_lock); 310 311 inode = mqueue_get_inode(dir->i_sb, ipc_ns, mode, attr); 312 if (IS_ERR(inode)) { 313 error = PTR_ERR(inode); 314 spin_lock(&mq_lock); 315 ipc_ns->mq_queues_count--; 316 goto out_unlock; 317 } 318 319 put_ipc_ns(ipc_ns); 320 dir->i_size += DIRENT_SIZE; 321 dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME; 322 323 d_instantiate(dentry, inode); 324 dget(dentry); 325 return 0; 326 out_unlock: 327 spin_unlock(&mq_lock); 328 if (ipc_ns) 329 put_ipc_ns(ipc_ns); 330 return error; 331 } 332 333 static int mqueue_unlink(struct inode *dir, struct dentry *dentry) 334 { 335 struct inode *inode = dentry->d_inode; 336 337 dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME; 338 dir->i_size -= DIRENT_SIZE; 339 drop_nlink(inode); 340 dput(dentry); 341 return 0; 342 } 343 344 /* 345 * This is routine for system read from queue file. 346 * To avoid mess with doing here some sort of mq_receive we allow 347 * to read only queue size & notification info (the only values 348 * that are interesting from user point of view and aren't accessible 349 * through std routines) 350 */ 351 static ssize_t mqueue_read_file(struct file *filp, char __user *u_data, 352 size_t count, loff_t *off) 353 { 354 struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode); 355 char buffer[FILENT_SIZE]; 356 ssize_t ret; 357 358 spin_lock(&info->lock); 359 snprintf(buffer, sizeof(buffer), 360 "QSIZE:%-10lu NOTIFY:%-5d SIGNO:%-5d NOTIFY_PID:%-6d\n", 361 info->qsize, 362 info->notify_owner ? info->notify.sigev_notify : 0, 363 (info->notify_owner && 364 info->notify.sigev_notify == SIGEV_SIGNAL) ? 365 info->notify.sigev_signo : 0, 366 pid_vnr(info->notify_owner)); 367 spin_unlock(&info->lock); 368 buffer[sizeof(buffer)-1] = '\0'; 369 370 ret = simple_read_from_buffer(u_data, count, off, buffer, 371 strlen(buffer)); 372 if (ret <= 0) 373 return ret; 374 375 filp->f_path.dentry->d_inode->i_atime = filp->f_path.dentry->d_inode->i_ctime = CURRENT_TIME; 376 return ret; 377 } 378 379 static int mqueue_flush_file(struct file *filp, fl_owner_t id) 380 { 381 struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode); 382 383 spin_lock(&info->lock); 384 if (task_tgid(current) == info->notify_owner) 385 remove_notification(info); 386 387 spin_unlock(&info->lock); 388 return 0; 389 } 390 391 static unsigned int mqueue_poll_file(struct file *filp, struct poll_table_struct *poll_tab) 392 { 393 struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode); 394 int retval = 0; 395 396 poll_wait(filp, &info->wait_q, poll_tab); 397 398 spin_lock(&info->lock); 399 if (info->attr.mq_curmsgs) 400 retval = POLLIN | POLLRDNORM; 401 402 if (info->attr.mq_curmsgs < info->attr.mq_maxmsg) 403 retval |= POLLOUT | POLLWRNORM; 404 spin_unlock(&info->lock); 405 406 return retval; 407 } 408 409 /* Adds current to info->e_wait_q[sr] before element with smaller prio */ 410 static void wq_add(struct mqueue_inode_info *info, int sr, 411 struct ext_wait_queue *ewp) 412 { 413 struct ext_wait_queue *walk; 414 415 ewp->task = current; 416 417 list_for_each_entry(walk, &info->e_wait_q[sr].list, list) { 418 if (walk->task->static_prio <= current->static_prio) { 419 list_add_tail(&ewp->list, &walk->list); 420 return; 421 } 422 } 423 list_add_tail(&ewp->list, &info->e_wait_q[sr].list); 424 } 425 426 /* 427 * Puts current task to sleep. Caller must hold queue lock. After return 428 * lock isn't held. 429 * sr: SEND or RECV 430 */ 431 static int wq_sleep(struct mqueue_inode_info *info, int sr, 432 ktime_t *timeout, struct ext_wait_queue *ewp) 433 { 434 int retval; 435 signed long time; 436 437 wq_add(info, sr, ewp); 438 439 for (;;) { 440 set_current_state(TASK_INTERRUPTIBLE); 441 442 spin_unlock(&info->lock); 443 time = schedule_hrtimeout_range_clock(timeout, 0, 444 HRTIMER_MODE_ABS, CLOCK_REALTIME); 445 446 while (ewp->state == STATE_PENDING) 447 cpu_relax(); 448 449 if (ewp->state == STATE_READY) { 450 retval = 0; 451 goto out; 452 } 453 spin_lock(&info->lock); 454 if (ewp->state == STATE_READY) { 455 retval = 0; 456 goto out_unlock; 457 } 458 if (signal_pending(current)) { 459 retval = -ERESTARTSYS; 460 break; 461 } 462 if (time == 0) { 463 retval = -ETIMEDOUT; 464 break; 465 } 466 } 467 list_del(&ewp->list); 468 out_unlock: 469 spin_unlock(&info->lock); 470 out: 471 return retval; 472 } 473 474 /* 475 * Returns waiting task that should be serviced first or NULL if none exists 476 */ 477 static struct ext_wait_queue *wq_get_first_waiter( 478 struct mqueue_inode_info *info, int sr) 479 { 480 struct list_head *ptr; 481 482 ptr = info->e_wait_q[sr].list.prev; 483 if (ptr == &info->e_wait_q[sr].list) 484 return NULL; 485 return list_entry(ptr, struct ext_wait_queue, list); 486 } 487 488 /* Auxiliary functions to manipulate messages' list */ 489 static void msg_insert(struct msg_msg *ptr, struct mqueue_inode_info *info) 490 { 491 int k; 492 493 k = info->attr.mq_curmsgs - 1; 494 while (k >= 0 && info->messages[k]->m_type >= ptr->m_type) { 495 info->messages[k + 1] = info->messages[k]; 496 k--; 497 } 498 info->attr.mq_curmsgs++; 499 info->qsize += ptr->m_ts; 500 info->messages[k + 1] = ptr; 501 } 502 503 static inline struct msg_msg *msg_get(struct mqueue_inode_info *info) 504 { 505 info->qsize -= info->messages[--info->attr.mq_curmsgs]->m_ts; 506 return info->messages[info->attr.mq_curmsgs]; 507 } 508 509 static inline void set_cookie(struct sk_buff *skb, char code) 510 { 511 ((char*)skb->data)[NOTIFY_COOKIE_LEN-1] = code; 512 } 513 514 /* 515 * The next function is only to split too long sys_mq_timedsend 516 */ 517 static void __do_notify(struct mqueue_inode_info *info) 518 { 519 /* notification 520 * invoked when there is registered process and there isn't process 521 * waiting synchronously for message AND state of queue changed from 522 * empty to not empty. Here we are sure that no one is waiting 523 * synchronously. */ 524 if (info->notify_owner && 525 info->attr.mq_curmsgs == 1) { 526 struct siginfo sig_i; 527 switch (info->notify.sigev_notify) { 528 case SIGEV_NONE: 529 break; 530 case SIGEV_SIGNAL: 531 /* sends signal */ 532 533 sig_i.si_signo = info->notify.sigev_signo; 534 sig_i.si_errno = 0; 535 sig_i.si_code = SI_MESGQ; 536 sig_i.si_value = info->notify.sigev_value; 537 /* map current pid/uid into info->owner's namespaces */ 538 rcu_read_lock(); 539 sig_i.si_pid = task_tgid_nr_ns(current, 540 ns_of_pid(info->notify_owner)); 541 sig_i.si_uid = from_kuid_munged(info->notify_user_ns, current_uid()); 542 rcu_read_unlock(); 543 544 kill_pid_info(info->notify.sigev_signo, 545 &sig_i, info->notify_owner); 546 break; 547 case SIGEV_THREAD: 548 set_cookie(info->notify_cookie, NOTIFY_WOKENUP); 549 netlink_sendskb(info->notify_sock, info->notify_cookie); 550 break; 551 } 552 /* after notification unregisters process */ 553 put_pid(info->notify_owner); 554 put_user_ns(info->notify_user_ns); 555 info->notify_owner = NULL; 556 info->notify_user_ns = NULL; 557 } 558 wake_up(&info->wait_q); 559 } 560 561 static int prepare_timeout(const struct timespec __user *u_abs_timeout, 562 ktime_t *expires, struct timespec *ts) 563 { 564 if (copy_from_user(ts, u_abs_timeout, sizeof(struct timespec))) 565 return -EFAULT; 566 if (!timespec_valid(ts)) 567 return -EINVAL; 568 569 *expires = timespec_to_ktime(*ts); 570 return 0; 571 } 572 573 static void remove_notification(struct mqueue_inode_info *info) 574 { 575 if (info->notify_owner != NULL && 576 info->notify.sigev_notify == SIGEV_THREAD) { 577 set_cookie(info->notify_cookie, NOTIFY_REMOVED); 578 netlink_sendskb(info->notify_sock, info->notify_cookie); 579 } 580 put_pid(info->notify_owner); 581 put_user_ns(info->notify_user_ns); 582 info->notify_owner = NULL; 583 info->notify_user_ns = NULL; 584 } 585 586 static int mq_attr_ok(struct ipc_namespace *ipc_ns, struct mq_attr *attr) 587 { 588 if (attr->mq_maxmsg <= 0 || attr->mq_msgsize <= 0) 589 return 0; 590 if (capable(CAP_SYS_RESOURCE)) { 591 if (attr->mq_maxmsg > HARD_MSGMAX) 592 return 0; 593 } else { 594 if (attr->mq_maxmsg > ipc_ns->mq_msg_max || 595 attr->mq_msgsize > ipc_ns->mq_msgsize_max) 596 return 0; 597 } 598 /* check for overflow */ 599 if (attr->mq_msgsize > ULONG_MAX/attr->mq_maxmsg) 600 return 0; 601 if ((unsigned long)(attr->mq_maxmsg * (attr->mq_msgsize 602 + sizeof (struct msg_msg *))) < 603 (unsigned long)(attr->mq_maxmsg * attr->mq_msgsize)) 604 return 0; 605 return 1; 606 } 607 608 /* 609 * Invoked when creating a new queue via sys_mq_open 610 */ 611 static struct file *do_create(struct ipc_namespace *ipc_ns, struct dentry *dir, 612 struct dentry *dentry, int oflag, umode_t mode, 613 struct mq_attr *attr) 614 { 615 const struct cred *cred = current_cred(); 616 struct file *result; 617 int ret; 618 619 if (attr) { 620 if (!mq_attr_ok(ipc_ns, attr)) { 621 ret = -EINVAL; 622 goto out; 623 } 624 /* store for use during create */ 625 dentry->d_fsdata = attr; 626 } 627 628 mode &= ~current_umask(); 629 ret = mnt_want_write(ipc_ns->mq_mnt); 630 if (ret) 631 goto out; 632 ret = vfs_create(dir->d_inode, dentry, mode, NULL); 633 dentry->d_fsdata = NULL; 634 if (ret) 635 goto out_drop_write; 636 637 result = dentry_open(dentry, ipc_ns->mq_mnt, oflag, cred); 638 /* 639 * dentry_open() took a persistent mnt_want_write(), 640 * so we can now drop this one. 641 */ 642 mnt_drop_write(ipc_ns->mq_mnt); 643 return result; 644 645 out_drop_write: 646 mnt_drop_write(ipc_ns->mq_mnt); 647 out: 648 dput(dentry); 649 mntput(ipc_ns->mq_mnt); 650 return ERR_PTR(ret); 651 } 652 653 /* Opens existing queue */ 654 static struct file *do_open(struct ipc_namespace *ipc_ns, 655 struct dentry *dentry, int oflag) 656 { 657 int ret; 658 const struct cred *cred = current_cred(); 659 660 static const int oflag2acc[O_ACCMODE] = { MAY_READ, MAY_WRITE, 661 MAY_READ | MAY_WRITE }; 662 663 if ((oflag & O_ACCMODE) == (O_RDWR | O_WRONLY)) { 664 ret = -EINVAL; 665 goto err; 666 } 667 668 if (inode_permission(dentry->d_inode, oflag2acc[oflag & O_ACCMODE])) { 669 ret = -EACCES; 670 goto err; 671 } 672 673 return dentry_open(dentry, ipc_ns->mq_mnt, oflag, cred); 674 675 err: 676 dput(dentry); 677 mntput(ipc_ns->mq_mnt); 678 return ERR_PTR(ret); 679 } 680 681 SYSCALL_DEFINE4(mq_open, const char __user *, u_name, int, oflag, umode_t, mode, 682 struct mq_attr __user *, u_attr) 683 { 684 struct dentry *dentry; 685 struct file *filp; 686 char *name; 687 struct mq_attr attr; 688 int fd, error; 689 struct ipc_namespace *ipc_ns = current->nsproxy->ipc_ns; 690 691 if (u_attr && copy_from_user(&attr, u_attr, sizeof(struct mq_attr))) 692 return -EFAULT; 693 694 audit_mq_open(oflag, mode, u_attr ? &attr : NULL); 695 696 if (IS_ERR(name = getname(u_name))) 697 return PTR_ERR(name); 698 699 fd = get_unused_fd_flags(O_CLOEXEC); 700 if (fd < 0) 701 goto out_putname; 702 703 mutex_lock(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex); 704 dentry = lookup_one_len(name, ipc_ns->mq_mnt->mnt_root, strlen(name)); 705 if (IS_ERR(dentry)) { 706 error = PTR_ERR(dentry); 707 goto out_putfd; 708 } 709 mntget(ipc_ns->mq_mnt); 710 711 if (oflag & O_CREAT) { 712 if (dentry->d_inode) { /* entry already exists */ 713 audit_inode(name, dentry); 714 if (oflag & O_EXCL) { 715 error = -EEXIST; 716 goto out; 717 } 718 filp = do_open(ipc_ns, dentry, oflag); 719 } else { 720 filp = do_create(ipc_ns, ipc_ns->mq_mnt->mnt_root, 721 dentry, oflag, mode, 722 u_attr ? &attr : NULL); 723 } 724 } else { 725 if (!dentry->d_inode) { 726 error = -ENOENT; 727 goto out; 728 } 729 audit_inode(name, dentry); 730 filp = do_open(ipc_ns, dentry, oflag); 731 } 732 733 if (IS_ERR(filp)) { 734 error = PTR_ERR(filp); 735 goto out_putfd; 736 } 737 738 fd_install(fd, filp); 739 goto out_upsem; 740 741 out: 742 dput(dentry); 743 mntput(ipc_ns->mq_mnt); 744 out_putfd: 745 put_unused_fd(fd); 746 fd = error; 747 out_upsem: 748 mutex_unlock(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex); 749 out_putname: 750 putname(name); 751 return fd; 752 } 753 754 SYSCALL_DEFINE1(mq_unlink, const char __user *, u_name) 755 { 756 int err; 757 char *name; 758 struct dentry *dentry; 759 struct inode *inode = NULL; 760 struct ipc_namespace *ipc_ns = current->nsproxy->ipc_ns; 761 762 name = getname(u_name); 763 if (IS_ERR(name)) 764 return PTR_ERR(name); 765 766 mutex_lock_nested(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex, 767 I_MUTEX_PARENT); 768 dentry = lookup_one_len(name, ipc_ns->mq_mnt->mnt_root, strlen(name)); 769 if (IS_ERR(dentry)) { 770 err = PTR_ERR(dentry); 771 goto out_unlock; 772 } 773 774 if (!dentry->d_inode) { 775 err = -ENOENT; 776 goto out_err; 777 } 778 779 inode = dentry->d_inode; 780 if (inode) 781 ihold(inode); 782 err = mnt_want_write(ipc_ns->mq_mnt); 783 if (err) 784 goto out_err; 785 err = vfs_unlink(dentry->d_parent->d_inode, dentry); 786 mnt_drop_write(ipc_ns->mq_mnt); 787 out_err: 788 dput(dentry); 789 790 out_unlock: 791 mutex_unlock(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex); 792 putname(name); 793 if (inode) 794 iput(inode); 795 796 return err; 797 } 798 799 /* Pipelined send and receive functions. 800 * 801 * If a receiver finds no waiting message, then it registers itself in the 802 * list of waiting receivers. A sender checks that list before adding the new 803 * message into the message array. If there is a waiting receiver, then it 804 * bypasses the message array and directly hands the message over to the 805 * receiver. 806 * The receiver accepts the message and returns without grabbing the queue 807 * spinlock. Therefore an intermediate STATE_PENDING state and memory barriers 808 * are necessary. The same algorithm is used for sysv semaphores, see 809 * ipc/sem.c for more details. 810 * 811 * The same algorithm is used for senders. 812 */ 813 814 /* pipelined_send() - send a message directly to the task waiting in 815 * sys_mq_timedreceive() (without inserting message into a queue). 816 */ 817 static inline void pipelined_send(struct mqueue_inode_info *info, 818 struct msg_msg *message, 819 struct ext_wait_queue *receiver) 820 { 821 receiver->msg = message; 822 list_del(&receiver->list); 823 receiver->state = STATE_PENDING; 824 wake_up_process(receiver->task); 825 smp_wmb(); 826 receiver->state = STATE_READY; 827 } 828 829 /* pipelined_receive() - if there is task waiting in sys_mq_timedsend() 830 * gets its message and put to the queue (we have one free place for sure). */ 831 static inline void pipelined_receive(struct mqueue_inode_info *info) 832 { 833 struct ext_wait_queue *sender = wq_get_first_waiter(info, SEND); 834 835 if (!sender) { 836 /* for poll */ 837 wake_up_interruptible(&info->wait_q); 838 return; 839 } 840 msg_insert(sender->msg, info); 841 list_del(&sender->list); 842 sender->state = STATE_PENDING; 843 wake_up_process(sender->task); 844 smp_wmb(); 845 sender->state = STATE_READY; 846 } 847 848 SYSCALL_DEFINE5(mq_timedsend, mqd_t, mqdes, const char __user *, u_msg_ptr, 849 size_t, msg_len, unsigned int, msg_prio, 850 const struct timespec __user *, u_abs_timeout) 851 { 852 struct file *filp; 853 struct inode *inode; 854 struct ext_wait_queue wait; 855 struct ext_wait_queue *receiver; 856 struct msg_msg *msg_ptr; 857 struct mqueue_inode_info *info; 858 ktime_t expires, *timeout = NULL; 859 struct timespec ts; 860 int ret; 861 862 if (u_abs_timeout) { 863 int res = prepare_timeout(u_abs_timeout, &expires, &ts); 864 if (res) 865 return res; 866 timeout = &expires; 867 } 868 869 if (unlikely(msg_prio >= (unsigned long) MQ_PRIO_MAX)) 870 return -EINVAL; 871 872 audit_mq_sendrecv(mqdes, msg_len, msg_prio, timeout ? &ts : NULL); 873 874 filp = fget(mqdes); 875 if (unlikely(!filp)) { 876 ret = -EBADF; 877 goto out; 878 } 879 880 inode = filp->f_path.dentry->d_inode; 881 if (unlikely(filp->f_op != &mqueue_file_operations)) { 882 ret = -EBADF; 883 goto out_fput; 884 } 885 info = MQUEUE_I(inode); 886 audit_inode(NULL, filp->f_path.dentry); 887 888 if (unlikely(!(filp->f_mode & FMODE_WRITE))) { 889 ret = -EBADF; 890 goto out_fput; 891 } 892 893 if (unlikely(msg_len > info->attr.mq_msgsize)) { 894 ret = -EMSGSIZE; 895 goto out_fput; 896 } 897 898 /* First try to allocate memory, before doing anything with 899 * existing queues. */ 900 msg_ptr = load_msg(u_msg_ptr, msg_len); 901 if (IS_ERR(msg_ptr)) { 902 ret = PTR_ERR(msg_ptr); 903 goto out_fput; 904 } 905 msg_ptr->m_ts = msg_len; 906 msg_ptr->m_type = msg_prio; 907 908 spin_lock(&info->lock); 909 910 if (info->attr.mq_curmsgs == info->attr.mq_maxmsg) { 911 if (filp->f_flags & O_NONBLOCK) { 912 spin_unlock(&info->lock); 913 ret = -EAGAIN; 914 } else { 915 wait.task = current; 916 wait.msg = (void *) msg_ptr; 917 wait.state = STATE_NONE; 918 ret = wq_sleep(info, SEND, timeout, &wait); 919 } 920 if (ret < 0) 921 free_msg(msg_ptr); 922 } else { 923 receiver = wq_get_first_waiter(info, RECV); 924 if (receiver) { 925 pipelined_send(info, msg_ptr, receiver); 926 } else { 927 /* adds message to the queue */ 928 msg_insert(msg_ptr, info); 929 __do_notify(info); 930 } 931 inode->i_atime = inode->i_mtime = inode->i_ctime = 932 CURRENT_TIME; 933 spin_unlock(&info->lock); 934 ret = 0; 935 } 936 out_fput: 937 fput(filp); 938 out: 939 return ret; 940 } 941 942 SYSCALL_DEFINE5(mq_timedreceive, mqd_t, mqdes, char __user *, u_msg_ptr, 943 size_t, msg_len, unsigned int __user *, u_msg_prio, 944 const struct timespec __user *, u_abs_timeout) 945 { 946 ssize_t ret; 947 struct msg_msg *msg_ptr; 948 struct file *filp; 949 struct inode *inode; 950 struct mqueue_inode_info *info; 951 struct ext_wait_queue wait; 952 ktime_t expires, *timeout = NULL; 953 struct timespec ts; 954 955 if (u_abs_timeout) { 956 int res = prepare_timeout(u_abs_timeout, &expires, &ts); 957 if (res) 958 return res; 959 timeout = &expires; 960 } 961 962 audit_mq_sendrecv(mqdes, msg_len, 0, timeout ? &ts : NULL); 963 964 filp = fget(mqdes); 965 if (unlikely(!filp)) { 966 ret = -EBADF; 967 goto out; 968 } 969 970 inode = filp->f_path.dentry->d_inode; 971 if (unlikely(filp->f_op != &mqueue_file_operations)) { 972 ret = -EBADF; 973 goto out_fput; 974 } 975 info = MQUEUE_I(inode); 976 audit_inode(NULL, filp->f_path.dentry); 977 978 if (unlikely(!(filp->f_mode & FMODE_READ))) { 979 ret = -EBADF; 980 goto out_fput; 981 } 982 983 /* checks if buffer is big enough */ 984 if (unlikely(msg_len < info->attr.mq_msgsize)) { 985 ret = -EMSGSIZE; 986 goto out_fput; 987 } 988 989 spin_lock(&info->lock); 990 if (info->attr.mq_curmsgs == 0) { 991 if (filp->f_flags & O_NONBLOCK) { 992 spin_unlock(&info->lock); 993 ret = -EAGAIN; 994 } else { 995 wait.task = current; 996 wait.state = STATE_NONE; 997 ret = wq_sleep(info, RECV, timeout, &wait); 998 msg_ptr = wait.msg; 999 } 1000 } else { 1001 msg_ptr = msg_get(info); 1002 1003 inode->i_atime = inode->i_mtime = inode->i_ctime = 1004 CURRENT_TIME; 1005 1006 /* There is now free space in queue. */ 1007 pipelined_receive(info); 1008 spin_unlock(&info->lock); 1009 ret = 0; 1010 } 1011 if (ret == 0) { 1012 ret = msg_ptr->m_ts; 1013 1014 if ((u_msg_prio && put_user(msg_ptr->m_type, u_msg_prio)) || 1015 store_msg(u_msg_ptr, msg_ptr, msg_ptr->m_ts)) { 1016 ret = -EFAULT; 1017 } 1018 free_msg(msg_ptr); 1019 } 1020 out_fput: 1021 fput(filp); 1022 out: 1023 return ret; 1024 } 1025 1026 /* 1027 * Notes: the case when user wants us to deregister (with NULL as pointer) 1028 * and he isn't currently owner of notification, will be silently discarded. 1029 * It isn't explicitly defined in the POSIX. 1030 */ 1031 SYSCALL_DEFINE2(mq_notify, mqd_t, mqdes, 1032 const struct sigevent __user *, u_notification) 1033 { 1034 int ret; 1035 struct file *filp; 1036 struct sock *sock; 1037 struct inode *inode; 1038 struct sigevent notification; 1039 struct mqueue_inode_info *info; 1040 struct sk_buff *nc; 1041 1042 if (u_notification) { 1043 if (copy_from_user(¬ification, u_notification, 1044 sizeof(struct sigevent))) 1045 return -EFAULT; 1046 } 1047 1048 audit_mq_notify(mqdes, u_notification ? ¬ification : NULL); 1049 1050 nc = NULL; 1051 sock = NULL; 1052 if (u_notification != NULL) { 1053 if (unlikely(notification.sigev_notify != SIGEV_NONE && 1054 notification.sigev_notify != SIGEV_SIGNAL && 1055 notification.sigev_notify != SIGEV_THREAD)) 1056 return -EINVAL; 1057 if (notification.sigev_notify == SIGEV_SIGNAL && 1058 !valid_signal(notification.sigev_signo)) { 1059 return -EINVAL; 1060 } 1061 if (notification.sigev_notify == SIGEV_THREAD) { 1062 long timeo; 1063 1064 /* create the notify skb */ 1065 nc = alloc_skb(NOTIFY_COOKIE_LEN, GFP_KERNEL); 1066 if (!nc) { 1067 ret = -ENOMEM; 1068 goto out; 1069 } 1070 if (copy_from_user(nc->data, 1071 notification.sigev_value.sival_ptr, 1072 NOTIFY_COOKIE_LEN)) { 1073 ret = -EFAULT; 1074 goto out; 1075 } 1076 1077 /* TODO: add a header? */ 1078 skb_put(nc, NOTIFY_COOKIE_LEN); 1079 /* and attach it to the socket */ 1080 retry: 1081 filp = fget(notification.sigev_signo); 1082 if (!filp) { 1083 ret = -EBADF; 1084 goto out; 1085 } 1086 sock = netlink_getsockbyfilp(filp); 1087 fput(filp); 1088 if (IS_ERR(sock)) { 1089 ret = PTR_ERR(sock); 1090 sock = NULL; 1091 goto out; 1092 } 1093 1094 timeo = MAX_SCHEDULE_TIMEOUT; 1095 ret = netlink_attachskb(sock, nc, &timeo, NULL); 1096 if (ret == 1) 1097 goto retry; 1098 if (ret) { 1099 sock = NULL; 1100 nc = NULL; 1101 goto out; 1102 } 1103 } 1104 } 1105 1106 filp = fget(mqdes); 1107 if (!filp) { 1108 ret = -EBADF; 1109 goto out; 1110 } 1111 1112 inode = filp->f_path.dentry->d_inode; 1113 if (unlikely(filp->f_op != &mqueue_file_operations)) { 1114 ret = -EBADF; 1115 goto out_fput; 1116 } 1117 info = MQUEUE_I(inode); 1118 1119 ret = 0; 1120 spin_lock(&info->lock); 1121 if (u_notification == NULL) { 1122 if (info->notify_owner == task_tgid(current)) { 1123 remove_notification(info); 1124 inode->i_atime = inode->i_ctime = CURRENT_TIME; 1125 } 1126 } else if (info->notify_owner != NULL) { 1127 ret = -EBUSY; 1128 } else { 1129 switch (notification.sigev_notify) { 1130 case SIGEV_NONE: 1131 info->notify.sigev_notify = SIGEV_NONE; 1132 break; 1133 case SIGEV_THREAD: 1134 info->notify_sock = sock; 1135 info->notify_cookie = nc; 1136 sock = NULL; 1137 nc = NULL; 1138 info->notify.sigev_notify = SIGEV_THREAD; 1139 break; 1140 case SIGEV_SIGNAL: 1141 info->notify.sigev_signo = notification.sigev_signo; 1142 info->notify.sigev_value = notification.sigev_value; 1143 info->notify.sigev_notify = SIGEV_SIGNAL; 1144 break; 1145 } 1146 1147 info->notify_owner = get_pid(task_tgid(current)); 1148 info->notify_user_ns = get_user_ns(current_user_ns()); 1149 inode->i_atime = inode->i_ctime = CURRENT_TIME; 1150 } 1151 spin_unlock(&info->lock); 1152 out_fput: 1153 fput(filp); 1154 out: 1155 if (sock) { 1156 netlink_detachskb(sock, nc); 1157 } else if (nc) { 1158 dev_kfree_skb(nc); 1159 } 1160 return ret; 1161 } 1162 1163 SYSCALL_DEFINE3(mq_getsetattr, mqd_t, mqdes, 1164 const struct mq_attr __user *, u_mqstat, 1165 struct mq_attr __user *, u_omqstat) 1166 { 1167 int ret; 1168 struct mq_attr mqstat, omqstat; 1169 struct file *filp; 1170 struct inode *inode; 1171 struct mqueue_inode_info *info; 1172 1173 if (u_mqstat != NULL) { 1174 if (copy_from_user(&mqstat, u_mqstat, sizeof(struct mq_attr))) 1175 return -EFAULT; 1176 if (mqstat.mq_flags & (~O_NONBLOCK)) 1177 return -EINVAL; 1178 } 1179 1180 filp = fget(mqdes); 1181 if (!filp) { 1182 ret = -EBADF; 1183 goto out; 1184 } 1185 1186 inode = filp->f_path.dentry->d_inode; 1187 if (unlikely(filp->f_op != &mqueue_file_operations)) { 1188 ret = -EBADF; 1189 goto out_fput; 1190 } 1191 info = MQUEUE_I(inode); 1192 1193 spin_lock(&info->lock); 1194 1195 omqstat = info->attr; 1196 omqstat.mq_flags = filp->f_flags & O_NONBLOCK; 1197 if (u_mqstat) { 1198 audit_mq_getsetattr(mqdes, &mqstat); 1199 spin_lock(&filp->f_lock); 1200 if (mqstat.mq_flags & O_NONBLOCK) 1201 filp->f_flags |= O_NONBLOCK; 1202 else 1203 filp->f_flags &= ~O_NONBLOCK; 1204 spin_unlock(&filp->f_lock); 1205 1206 inode->i_atime = inode->i_ctime = CURRENT_TIME; 1207 } 1208 1209 spin_unlock(&info->lock); 1210 1211 ret = 0; 1212 if (u_omqstat != NULL && copy_to_user(u_omqstat, &omqstat, 1213 sizeof(struct mq_attr))) 1214 ret = -EFAULT; 1215 1216 out_fput: 1217 fput(filp); 1218 out: 1219 return ret; 1220 } 1221 1222 static const struct inode_operations mqueue_dir_inode_operations = { 1223 .lookup = simple_lookup, 1224 .create = mqueue_create, 1225 .unlink = mqueue_unlink, 1226 }; 1227 1228 static const struct file_operations mqueue_file_operations = { 1229 .flush = mqueue_flush_file, 1230 .poll = mqueue_poll_file, 1231 .read = mqueue_read_file, 1232 .llseek = default_llseek, 1233 }; 1234 1235 static const struct super_operations mqueue_super_ops = { 1236 .alloc_inode = mqueue_alloc_inode, 1237 .destroy_inode = mqueue_destroy_inode, 1238 .evict_inode = mqueue_evict_inode, 1239 .statfs = simple_statfs, 1240 }; 1241 1242 static struct file_system_type mqueue_fs_type = { 1243 .name = "mqueue", 1244 .mount = mqueue_mount, 1245 .kill_sb = kill_litter_super, 1246 }; 1247 1248 int mq_init_ns(struct ipc_namespace *ns) 1249 { 1250 ns->mq_queues_count = 0; 1251 ns->mq_queues_max = DFLT_QUEUESMAX; 1252 ns->mq_msg_max = DFLT_MSGMAX; 1253 ns->mq_msgsize_max = DFLT_MSGSIZEMAX; 1254 1255 ns->mq_mnt = kern_mount_data(&mqueue_fs_type, ns); 1256 if (IS_ERR(ns->mq_mnt)) { 1257 int err = PTR_ERR(ns->mq_mnt); 1258 ns->mq_mnt = NULL; 1259 return err; 1260 } 1261 return 0; 1262 } 1263 1264 void mq_clear_sbinfo(struct ipc_namespace *ns) 1265 { 1266 ns->mq_mnt->mnt_sb->s_fs_info = NULL; 1267 } 1268 1269 void mq_put_mnt(struct ipc_namespace *ns) 1270 { 1271 kern_unmount(ns->mq_mnt); 1272 } 1273 1274 static int __init init_mqueue_fs(void) 1275 { 1276 int error; 1277 1278 mqueue_inode_cachep = kmem_cache_create("mqueue_inode_cache", 1279 sizeof(struct mqueue_inode_info), 0, 1280 SLAB_HWCACHE_ALIGN, init_once); 1281 if (mqueue_inode_cachep == NULL) 1282 return -ENOMEM; 1283 1284 /* ignore failures - they are not fatal */ 1285 mq_sysctl_table = mq_register_sysctl_table(); 1286 1287 error = register_filesystem(&mqueue_fs_type); 1288 if (error) 1289 goto out_sysctl; 1290 1291 spin_lock_init(&mq_lock); 1292 1293 error = mq_init_ns(&init_ipc_ns); 1294 if (error) 1295 goto out_filesystem; 1296 1297 return 0; 1298 1299 out_filesystem: 1300 unregister_filesystem(&mqueue_fs_type); 1301 out_sysctl: 1302 if (mq_sysctl_table) 1303 unregister_sysctl_table(mq_sysctl_table); 1304 kmem_cache_destroy(mqueue_inode_cachep); 1305 return error; 1306 } 1307 1308 __initcall(init_mqueue_fs); 1309