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/vmalloc.h> 28 #include <linux/netlink.h> 29 #include <linux/syscalls.h> 30 #include <linux/audit.h> 31 #include <linux/signal.h> 32 #include <linux/mutex.h> 33 #include <linux/nsproxy.h> 34 #include <linux/pid.h> 35 #include <linux/ipc_namespace.h> 36 #include <linux/user_namespace.h> 37 #include <linux/slab.h> 38 39 #include <net/sock.h> 40 #include "util.h" 41 42 #define MQUEUE_MAGIC 0x19800202 43 #define DIRENT_SIZE 20 44 #define FILENT_SIZE 80 45 46 #define SEND 0 47 #define RECV 1 48 49 #define STATE_NONE 0 50 #define STATE_PENDING 1 51 #define STATE_READY 2 52 53 struct ext_wait_queue { /* queue of sleeping tasks */ 54 struct task_struct *task; 55 struct list_head list; 56 struct msg_msg *msg; /* ptr of loaded message */ 57 int state; /* one of STATE_* values */ 58 }; 59 60 struct mqueue_inode_info { 61 spinlock_t lock; 62 struct inode vfs_inode; 63 wait_queue_head_t wait_q; 64 65 struct msg_msg **messages; 66 struct mq_attr attr; 67 68 struct sigevent notify; 69 struct pid* notify_owner; 70 struct user_namespace *notify_user_ns; 71 struct user_struct *user; /* user who created, for accounting */ 72 struct sock *notify_sock; 73 struct sk_buff *notify_cookie; 74 75 /* for tasks waiting for free space and messages, respectively */ 76 struct ext_wait_queue e_wait_q[2]; 77 78 unsigned long qsize; /* size of queue in memory (sum of all msgs) */ 79 }; 80 81 static const struct inode_operations mqueue_dir_inode_operations; 82 static const struct file_operations mqueue_file_operations; 83 static const struct super_operations mqueue_super_ops; 84 static void remove_notification(struct mqueue_inode_info *info); 85 86 static struct kmem_cache *mqueue_inode_cachep; 87 88 static struct ctl_table_header * mq_sysctl_table; 89 90 static inline struct mqueue_inode_info *MQUEUE_I(struct inode *inode) 91 { 92 return container_of(inode, struct mqueue_inode_info, vfs_inode); 93 } 94 95 /* 96 * This routine should be called with the mq_lock held. 97 */ 98 static inline struct ipc_namespace *__get_ns_from_inode(struct inode *inode) 99 { 100 return get_ipc_ns(inode->i_sb->s_fs_info); 101 } 102 103 static struct ipc_namespace *get_ns_from_inode(struct inode *inode) 104 { 105 struct ipc_namespace *ns; 106 107 spin_lock(&mq_lock); 108 ns = __get_ns_from_inode(inode); 109 spin_unlock(&mq_lock); 110 return ns; 111 } 112 113 static struct inode *mqueue_get_inode(struct super_block *sb, 114 struct ipc_namespace *ipc_ns, umode_t mode, 115 struct mq_attr *attr) 116 { 117 struct user_struct *u = current_user(); 118 struct inode *inode; 119 int ret = -ENOMEM; 120 121 inode = new_inode(sb); 122 if (!inode) 123 goto err; 124 125 inode->i_ino = get_next_ino(); 126 inode->i_mode = mode; 127 inode->i_uid = current_fsuid(); 128 inode->i_gid = current_fsgid(); 129 inode->i_mtime = inode->i_ctime = inode->i_atime = CURRENT_TIME; 130 131 if (S_ISREG(mode)) { 132 struct mqueue_inode_info *info; 133 unsigned long mq_bytes, mq_msg_tblsz; 134 135 inode->i_fop = &mqueue_file_operations; 136 inode->i_size = FILENT_SIZE; 137 /* mqueue specific info */ 138 info = MQUEUE_I(inode); 139 spin_lock_init(&info->lock); 140 init_waitqueue_head(&info->wait_q); 141 INIT_LIST_HEAD(&info->e_wait_q[0].list); 142 INIT_LIST_HEAD(&info->e_wait_q[1].list); 143 info->notify_owner = NULL; 144 info->notify_user_ns = NULL; 145 info->qsize = 0; 146 info->user = NULL; /* set when all is ok */ 147 memset(&info->attr, 0, sizeof(info->attr)); 148 info->attr.mq_maxmsg = min(ipc_ns->mq_msg_max, 149 ipc_ns->mq_msg_default); 150 info->attr.mq_msgsize = min(ipc_ns->mq_msgsize_max, 151 ipc_ns->mq_msgsize_default); 152 if (attr) { 153 info->attr.mq_maxmsg = attr->mq_maxmsg; 154 info->attr.mq_msgsize = attr->mq_msgsize; 155 } 156 mq_msg_tblsz = info->attr.mq_maxmsg * sizeof(struct msg_msg *); 157 if (mq_msg_tblsz > PAGE_SIZE) 158 info->messages = vmalloc(mq_msg_tblsz); 159 else 160 info->messages = kmalloc(mq_msg_tblsz, GFP_KERNEL); 161 if (!info->messages) 162 goto out_inode; 163 164 mq_bytes = (mq_msg_tblsz + 165 (info->attr.mq_maxmsg * info->attr.mq_msgsize)); 166 167 spin_lock(&mq_lock); 168 if (u->mq_bytes + mq_bytes < u->mq_bytes || 169 u->mq_bytes + mq_bytes > rlimit(RLIMIT_MSGQUEUE)) { 170 spin_unlock(&mq_lock); 171 /* mqueue_evict_inode() releases info->messages */ 172 ret = -EMFILE; 173 goto out_inode; 174 } 175 u->mq_bytes += mq_bytes; 176 spin_unlock(&mq_lock); 177 178 /* all is ok */ 179 info->user = get_uid(u); 180 } else if (S_ISDIR(mode)) { 181 inc_nlink(inode); 182 /* Some things misbehave if size == 0 on a directory */ 183 inode->i_size = 2 * DIRENT_SIZE; 184 inode->i_op = &mqueue_dir_inode_operations; 185 inode->i_fop = &simple_dir_operations; 186 } 187 188 return inode; 189 out_inode: 190 iput(inode); 191 err: 192 return ERR_PTR(ret); 193 } 194 195 static int mqueue_fill_super(struct super_block *sb, void *data, int silent) 196 { 197 struct inode *inode; 198 struct ipc_namespace *ns = data; 199 200 sb->s_blocksize = PAGE_CACHE_SIZE; 201 sb->s_blocksize_bits = PAGE_CACHE_SHIFT; 202 sb->s_magic = MQUEUE_MAGIC; 203 sb->s_op = &mqueue_super_ops; 204 205 inode = mqueue_get_inode(sb, ns, S_IFDIR | S_ISVTX | S_IRWXUGO, NULL); 206 if (IS_ERR(inode)) 207 return PTR_ERR(inode); 208 209 sb->s_root = d_make_root(inode); 210 if (!sb->s_root) 211 return -ENOMEM; 212 return 0; 213 } 214 215 static struct dentry *mqueue_mount(struct file_system_type *fs_type, 216 int flags, const char *dev_name, 217 void *data) 218 { 219 if (!(flags & MS_KERNMOUNT)) 220 data = current->nsproxy->ipc_ns; 221 return mount_ns(fs_type, flags, data, mqueue_fill_super); 222 } 223 224 static void init_once(void *foo) 225 { 226 struct mqueue_inode_info *p = (struct mqueue_inode_info *) foo; 227 228 inode_init_once(&p->vfs_inode); 229 } 230 231 static struct inode *mqueue_alloc_inode(struct super_block *sb) 232 { 233 struct mqueue_inode_info *ei; 234 235 ei = kmem_cache_alloc(mqueue_inode_cachep, GFP_KERNEL); 236 if (!ei) 237 return NULL; 238 return &ei->vfs_inode; 239 } 240 241 static void mqueue_i_callback(struct rcu_head *head) 242 { 243 struct inode *inode = container_of(head, struct inode, i_rcu); 244 kmem_cache_free(mqueue_inode_cachep, MQUEUE_I(inode)); 245 } 246 247 static void mqueue_destroy_inode(struct inode *inode) 248 { 249 call_rcu(&inode->i_rcu, mqueue_i_callback); 250 } 251 252 static void mqueue_evict_inode(struct inode *inode) 253 { 254 struct mqueue_inode_info *info; 255 struct user_struct *user; 256 unsigned long mq_bytes; 257 int i; 258 struct ipc_namespace *ipc_ns; 259 260 clear_inode(inode); 261 262 if (S_ISDIR(inode->i_mode)) 263 return; 264 265 ipc_ns = get_ns_from_inode(inode); 266 info = MQUEUE_I(inode); 267 spin_lock(&info->lock); 268 for (i = 0; i < info->attr.mq_curmsgs; i++) 269 free_msg(info->messages[i]); 270 if (is_vmalloc_addr(info->messages)) 271 vfree(info->messages); 272 else 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 >= HARD_QUEUESMAX || 313 (ipc_ns->mq_queues_count >= ipc_ns->mq_queues_max && 314 !capable(CAP_SYS_RESOURCE))) { 315 error = -ENOSPC; 316 goto out_unlock; 317 } 318 ipc_ns->mq_queues_count++; 319 spin_unlock(&mq_lock); 320 321 inode = mqueue_get_inode(dir->i_sb, ipc_ns, mode, attr); 322 if (IS_ERR(inode)) { 323 error = PTR_ERR(inode); 324 spin_lock(&mq_lock); 325 ipc_ns->mq_queues_count--; 326 goto out_unlock; 327 } 328 329 put_ipc_ns(ipc_ns); 330 dir->i_size += DIRENT_SIZE; 331 dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME; 332 333 d_instantiate(dentry, inode); 334 dget(dentry); 335 return 0; 336 out_unlock: 337 spin_unlock(&mq_lock); 338 if (ipc_ns) 339 put_ipc_ns(ipc_ns); 340 return error; 341 } 342 343 static int mqueue_unlink(struct inode *dir, struct dentry *dentry) 344 { 345 struct inode *inode = dentry->d_inode; 346 347 dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME; 348 dir->i_size -= DIRENT_SIZE; 349 drop_nlink(inode); 350 dput(dentry); 351 return 0; 352 } 353 354 /* 355 * This is routine for system read from queue file. 356 * To avoid mess with doing here some sort of mq_receive we allow 357 * to read only queue size & notification info (the only values 358 * that are interesting from user point of view and aren't accessible 359 * through std routines) 360 */ 361 static ssize_t mqueue_read_file(struct file *filp, char __user *u_data, 362 size_t count, loff_t *off) 363 { 364 struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode); 365 char buffer[FILENT_SIZE]; 366 ssize_t ret; 367 368 spin_lock(&info->lock); 369 snprintf(buffer, sizeof(buffer), 370 "QSIZE:%-10lu NOTIFY:%-5d SIGNO:%-5d NOTIFY_PID:%-6d\n", 371 info->qsize, 372 info->notify_owner ? info->notify.sigev_notify : 0, 373 (info->notify_owner && 374 info->notify.sigev_notify == SIGEV_SIGNAL) ? 375 info->notify.sigev_signo : 0, 376 pid_vnr(info->notify_owner)); 377 spin_unlock(&info->lock); 378 buffer[sizeof(buffer)-1] = '\0'; 379 380 ret = simple_read_from_buffer(u_data, count, off, buffer, 381 strlen(buffer)); 382 if (ret <= 0) 383 return ret; 384 385 filp->f_path.dentry->d_inode->i_atime = filp->f_path.dentry->d_inode->i_ctime = CURRENT_TIME; 386 return ret; 387 } 388 389 static int mqueue_flush_file(struct file *filp, fl_owner_t id) 390 { 391 struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode); 392 393 spin_lock(&info->lock); 394 if (task_tgid(current) == info->notify_owner) 395 remove_notification(info); 396 397 spin_unlock(&info->lock); 398 return 0; 399 } 400 401 static unsigned int mqueue_poll_file(struct file *filp, struct poll_table_struct *poll_tab) 402 { 403 struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode); 404 int retval = 0; 405 406 poll_wait(filp, &info->wait_q, poll_tab); 407 408 spin_lock(&info->lock); 409 if (info->attr.mq_curmsgs) 410 retval = POLLIN | POLLRDNORM; 411 412 if (info->attr.mq_curmsgs < info->attr.mq_maxmsg) 413 retval |= POLLOUT | POLLWRNORM; 414 spin_unlock(&info->lock); 415 416 return retval; 417 } 418 419 /* Adds current to info->e_wait_q[sr] before element with smaller prio */ 420 static void wq_add(struct mqueue_inode_info *info, int sr, 421 struct ext_wait_queue *ewp) 422 { 423 struct ext_wait_queue *walk; 424 425 ewp->task = current; 426 427 list_for_each_entry(walk, &info->e_wait_q[sr].list, list) { 428 if (walk->task->static_prio <= current->static_prio) { 429 list_add_tail(&ewp->list, &walk->list); 430 return; 431 } 432 } 433 list_add_tail(&ewp->list, &info->e_wait_q[sr].list); 434 } 435 436 /* 437 * Puts current task to sleep. Caller must hold queue lock. After return 438 * lock isn't held. 439 * sr: SEND or RECV 440 */ 441 static int wq_sleep(struct mqueue_inode_info *info, int sr, 442 ktime_t *timeout, struct ext_wait_queue *ewp) 443 { 444 int retval; 445 signed long time; 446 447 wq_add(info, sr, ewp); 448 449 for (;;) { 450 set_current_state(TASK_INTERRUPTIBLE); 451 452 spin_unlock(&info->lock); 453 time = schedule_hrtimeout_range_clock(timeout, 0, 454 HRTIMER_MODE_ABS, CLOCK_REALTIME); 455 456 while (ewp->state == STATE_PENDING) 457 cpu_relax(); 458 459 if (ewp->state == STATE_READY) { 460 retval = 0; 461 goto out; 462 } 463 spin_lock(&info->lock); 464 if (ewp->state == STATE_READY) { 465 retval = 0; 466 goto out_unlock; 467 } 468 if (signal_pending(current)) { 469 retval = -ERESTARTSYS; 470 break; 471 } 472 if (time == 0) { 473 retval = -ETIMEDOUT; 474 break; 475 } 476 } 477 list_del(&ewp->list); 478 out_unlock: 479 spin_unlock(&info->lock); 480 out: 481 return retval; 482 } 483 484 /* 485 * Returns waiting task that should be serviced first or NULL if none exists 486 */ 487 static struct ext_wait_queue *wq_get_first_waiter( 488 struct mqueue_inode_info *info, int sr) 489 { 490 struct list_head *ptr; 491 492 ptr = info->e_wait_q[sr].list.prev; 493 if (ptr == &info->e_wait_q[sr].list) 494 return NULL; 495 return list_entry(ptr, struct ext_wait_queue, list); 496 } 497 498 /* Auxiliary functions to manipulate messages' list */ 499 static void msg_insert(struct msg_msg *ptr, struct mqueue_inode_info *info) 500 { 501 int k; 502 503 k = info->attr.mq_curmsgs - 1; 504 while (k >= 0 && info->messages[k]->m_type >= ptr->m_type) { 505 info->messages[k + 1] = info->messages[k]; 506 k--; 507 } 508 info->attr.mq_curmsgs++; 509 info->qsize += ptr->m_ts; 510 info->messages[k + 1] = ptr; 511 } 512 513 static inline struct msg_msg *msg_get(struct mqueue_inode_info *info) 514 { 515 info->qsize -= info->messages[--info->attr.mq_curmsgs]->m_ts; 516 return info->messages[info->attr.mq_curmsgs]; 517 } 518 519 static inline void set_cookie(struct sk_buff *skb, char code) 520 { 521 ((char*)skb->data)[NOTIFY_COOKIE_LEN-1] = code; 522 } 523 524 /* 525 * The next function is only to split too long sys_mq_timedsend 526 */ 527 static void __do_notify(struct mqueue_inode_info *info) 528 { 529 /* notification 530 * invoked when there is registered process and there isn't process 531 * waiting synchronously for message AND state of queue changed from 532 * empty to not empty. Here we are sure that no one is waiting 533 * synchronously. */ 534 if (info->notify_owner && 535 info->attr.mq_curmsgs == 1) { 536 struct siginfo sig_i; 537 switch (info->notify.sigev_notify) { 538 case SIGEV_NONE: 539 break; 540 case SIGEV_SIGNAL: 541 /* sends signal */ 542 543 sig_i.si_signo = info->notify.sigev_signo; 544 sig_i.si_errno = 0; 545 sig_i.si_code = SI_MESGQ; 546 sig_i.si_value = info->notify.sigev_value; 547 /* map current pid/uid into info->owner's namespaces */ 548 rcu_read_lock(); 549 sig_i.si_pid = task_tgid_nr_ns(current, 550 ns_of_pid(info->notify_owner)); 551 sig_i.si_uid = from_kuid_munged(info->notify_user_ns, 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 put_user_ns(info->notify_user_ns); 565 info->notify_owner = NULL; 566 info->notify_user_ns = NULL; 567 } 568 wake_up(&info->wait_q); 569 } 570 571 static int prepare_timeout(const struct timespec __user *u_abs_timeout, 572 ktime_t *expires, struct timespec *ts) 573 { 574 if (copy_from_user(ts, u_abs_timeout, sizeof(struct timespec))) 575 return -EFAULT; 576 if (!timespec_valid(ts)) 577 return -EINVAL; 578 579 *expires = timespec_to_ktime(*ts); 580 return 0; 581 } 582 583 static void remove_notification(struct mqueue_inode_info *info) 584 { 585 if (info->notify_owner != NULL && 586 info->notify.sigev_notify == SIGEV_THREAD) { 587 set_cookie(info->notify_cookie, NOTIFY_REMOVED); 588 netlink_sendskb(info->notify_sock, info->notify_cookie); 589 } 590 put_pid(info->notify_owner); 591 put_user_ns(info->notify_user_ns); 592 info->notify_owner = NULL; 593 info->notify_user_ns = NULL; 594 } 595 596 static int mq_attr_ok(struct ipc_namespace *ipc_ns, struct mq_attr *attr) 597 { 598 if (attr->mq_maxmsg <= 0 || attr->mq_msgsize <= 0) 599 return 0; 600 if (capable(CAP_SYS_RESOURCE)) { 601 if (attr->mq_maxmsg > HARD_MSGMAX || 602 attr->mq_msgsize > HARD_MSGSIZEMAX) 603 return 0; 604 } else { 605 if (attr->mq_maxmsg > ipc_ns->mq_msg_max || 606 attr->mq_msgsize > ipc_ns->mq_msgsize_max) 607 return 0; 608 } 609 /* check for overflow */ 610 if (attr->mq_msgsize > ULONG_MAX/attr->mq_maxmsg) 611 return 0; 612 if ((unsigned long)(attr->mq_maxmsg * (attr->mq_msgsize 613 + sizeof (struct msg_msg *))) < 614 (unsigned long)(attr->mq_maxmsg * attr->mq_msgsize)) 615 return 0; 616 return 1; 617 } 618 619 /* 620 * Invoked when creating a new queue via sys_mq_open 621 */ 622 static struct file *do_create(struct ipc_namespace *ipc_ns, struct dentry *dir, 623 struct dentry *dentry, int oflag, umode_t mode, 624 struct mq_attr *attr) 625 { 626 const struct cred *cred = current_cred(); 627 struct file *result; 628 int ret; 629 630 if (attr) { 631 if (!mq_attr_ok(ipc_ns, attr)) { 632 ret = -EINVAL; 633 goto out; 634 } 635 /* store for use during create */ 636 dentry->d_fsdata = attr; 637 } 638 639 mode &= ~current_umask(); 640 ret = mnt_want_write(ipc_ns->mq_mnt); 641 if (ret) 642 goto out; 643 ret = vfs_create(dir->d_inode, dentry, mode, NULL); 644 dentry->d_fsdata = NULL; 645 if (ret) 646 goto out_drop_write; 647 648 result = dentry_open(dentry, ipc_ns->mq_mnt, oflag, cred); 649 /* 650 * dentry_open() took a persistent mnt_want_write(), 651 * so we can now drop this one. 652 */ 653 mnt_drop_write(ipc_ns->mq_mnt); 654 return result; 655 656 out_drop_write: 657 mnt_drop_write(ipc_ns->mq_mnt); 658 out: 659 dput(dentry); 660 mntput(ipc_ns->mq_mnt); 661 return ERR_PTR(ret); 662 } 663 664 /* Opens existing queue */ 665 static struct file *do_open(struct ipc_namespace *ipc_ns, 666 struct dentry *dentry, int oflag) 667 { 668 int ret; 669 const struct cred *cred = current_cred(); 670 671 static const int oflag2acc[O_ACCMODE] = { MAY_READ, MAY_WRITE, 672 MAY_READ | MAY_WRITE }; 673 674 if ((oflag & O_ACCMODE) == (O_RDWR | O_WRONLY)) { 675 ret = -EINVAL; 676 goto err; 677 } 678 679 if (inode_permission(dentry->d_inode, oflag2acc[oflag & O_ACCMODE])) { 680 ret = -EACCES; 681 goto err; 682 } 683 684 return dentry_open(dentry, ipc_ns->mq_mnt, oflag, cred); 685 686 err: 687 dput(dentry); 688 mntput(ipc_ns->mq_mnt); 689 return ERR_PTR(ret); 690 } 691 692 SYSCALL_DEFINE4(mq_open, const char __user *, u_name, int, oflag, umode_t, mode, 693 struct mq_attr __user *, u_attr) 694 { 695 struct dentry *dentry; 696 struct file *filp; 697 char *name; 698 struct mq_attr attr; 699 int fd, error; 700 struct ipc_namespace *ipc_ns = current->nsproxy->ipc_ns; 701 702 if (u_attr && copy_from_user(&attr, u_attr, sizeof(struct mq_attr))) 703 return -EFAULT; 704 705 audit_mq_open(oflag, mode, u_attr ? &attr : NULL); 706 707 if (IS_ERR(name = getname(u_name))) 708 return PTR_ERR(name); 709 710 fd = get_unused_fd_flags(O_CLOEXEC); 711 if (fd < 0) 712 goto out_putname; 713 714 mutex_lock(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex); 715 dentry = lookup_one_len(name, ipc_ns->mq_mnt->mnt_root, strlen(name)); 716 if (IS_ERR(dentry)) { 717 error = PTR_ERR(dentry); 718 goto out_putfd; 719 } 720 mntget(ipc_ns->mq_mnt); 721 722 if (oflag & O_CREAT) { 723 if (dentry->d_inode) { /* entry already exists */ 724 audit_inode(name, dentry); 725 if (oflag & O_EXCL) { 726 error = -EEXIST; 727 goto out; 728 } 729 filp = do_open(ipc_ns, dentry, oflag); 730 } else { 731 filp = do_create(ipc_ns, ipc_ns->mq_mnt->mnt_root, 732 dentry, oflag, mode, 733 u_attr ? &attr : NULL); 734 } 735 } else { 736 if (!dentry->d_inode) { 737 error = -ENOENT; 738 goto out; 739 } 740 audit_inode(name, dentry); 741 filp = do_open(ipc_ns, dentry, oflag); 742 } 743 744 if (IS_ERR(filp)) { 745 error = PTR_ERR(filp); 746 goto out_putfd; 747 } 748 749 fd_install(fd, filp); 750 goto out_upsem; 751 752 out: 753 dput(dentry); 754 mntput(ipc_ns->mq_mnt); 755 out_putfd: 756 put_unused_fd(fd); 757 fd = error; 758 out_upsem: 759 mutex_unlock(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex); 760 out_putname: 761 putname(name); 762 return fd; 763 } 764 765 SYSCALL_DEFINE1(mq_unlink, const char __user *, u_name) 766 { 767 int err; 768 char *name; 769 struct dentry *dentry; 770 struct inode *inode = NULL; 771 struct ipc_namespace *ipc_ns = current->nsproxy->ipc_ns; 772 773 name = getname(u_name); 774 if (IS_ERR(name)) 775 return PTR_ERR(name); 776 777 mutex_lock_nested(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex, 778 I_MUTEX_PARENT); 779 dentry = lookup_one_len(name, ipc_ns->mq_mnt->mnt_root, strlen(name)); 780 if (IS_ERR(dentry)) { 781 err = PTR_ERR(dentry); 782 goto out_unlock; 783 } 784 785 if (!dentry->d_inode) { 786 err = -ENOENT; 787 goto out_err; 788 } 789 790 inode = dentry->d_inode; 791 if (inode) 792 ihold(inode); 793 err = mnt_want_write(ipc_ns->mq_mnt); 794 if (err) 795 goto out_err; 796 err = vfs_unlink(dentry->d_parent->d_inode, dentry); 797 mnt_drop_write(ipc_ns->mq_mnt); 798 out_err: 799 dput(dentry); 800 801 out_unlock: 802 mutex_unlock(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex); 803 putname(name); 804 if (inode) 805 iput(inode); 806 807 return err; 808 } 809 810 /* Pipelined send and receive functions. 811 * 812 * If a receiver finds no waiting message, then it registers itself in the 813 * list of waiting receivers. A sender checks that list before adding the new 814 * message into the message array. If there is a waiting receiver, then it 815 * bypasses the message array and directly hands the message over to the 816 * receiver. 817 * The receiver accepts the message and returns without grabbing the queue 818 * spinlock. Therefore an intermediate STATE_PENDING state and memory barriers 819 * are necessary. The same algorithm is used for sysv semaphores, see 820 * ipc/sem.c for more details. 821 * 822 * The same algorithm is used for senders. 823 */ 824 825 /* pipelined_send() - send a message directly to the task waiting in 826 * sys_mq_timedreceive() (without inserting message into a queue). 827 */ 828 static inline void pipelined_send(struct mqueue_inode_info *info, 829 struct msg_msg *message, 830 struct ext_wait_queue *receiver) 831 { 832 receiver->msg = message; 833 list_del(&receiver->list); 834 receiver->state = STATE_PENDING; 835 wake_up_process(receiver->task); 836 smp_wmb(); 837 receiver->state = STATE_READY; 838 } 839 840 /* pipelined_receive() - if there is task waiting in sys_mq_timedsend() 841 * gets its message and put to the queue (we have one free place for sure). */ 842 static inline void pipelined_receive(struct mqueue_inode_info *info) 843 { 844 struct ext_wait_queue *sender = wq_get_first_waiter(info, SEND); 845 846 if (!sender) { 847 /* for poll */ 848 wake_up_interruptible(&info->wait_q); 849 return; 850 } 851 msg_insert(sender->msg, info); 852 list_del(&sender->list); 853 sender->state = STATE_PENDING; 854 wake_up_process(sender->task); 855 smp_wmb(); 856 sender->state = STATE_READY; 857 } 858 859 SYSCALL_DEFINE5(mq_timedsend, mqd_t, mqdes, const char __user *, u_msg_ptr, 860 size_t, msg_len, unsigned int, msg_prio, 861 const struct timespec __user *, u_abs_timeout) 862 { 863 struct file *filp; 864 struct inode *inode; 865 struct ext_wait_queue wait; 866 struct ext_wait_queue *receiver; 867 struct msg_msg *msg_ptr; 868 struct mqueue_inode_info *info; 869 ktime_t expires, *timeout = NULL; 870 struct timespec ts; 871 int ret; 872 873 if (u_abs_timeout) { 874 int res = prepare_timeout(u_abs_timeout, &expires, &ts); 875 if (res) 876 return res; 877 timeout = &expires; 878 } 879 880 if (unlikely(msg_prio >= (unsigned long) MQ_PRIO_MAX)) 881 return -EINVAL; 882 883 audit_mq_sendrecv(mqdes, msg_len, msg_prio, timeout ? &ts : NULL); 884 885 filp = fget(mqdes); 886 if (unlikely(!filp)) { 887 ret = -EBADF; 888 goto out; 889 } 890 891 inode = filp->f_path.dentry->d_inode; 892 if (unlikely(filp->f_op != &mqueue_file_operations)) { 893 ret = -EBADF; 894 goto out_fput; 895 } 896 info = MQUEUE_I(inode); 897 audit_inode(NULL, filp->f_path.dentry); 898 899 if (unlikely(!(filp->f_mode & FMODE_WRITE))) { 900 ret = -EBADF; 901 goto out_fput; 902 } 903 904 if (unlikely(msg_len > info->attr.mq_msgsize)) { 905 ret = -EMSGSIZE; 906 goto out_fput; 907 } 908 909 /* First try to allocate memory, before doing anything with 910 * existing queues. */ 911 msg_ptr = load_msg(u_msg_ptr, msg_len); 912 if (IS_ERR(msg_ptr)) { 913 ret = PTR_ERR(msg_ptr); 914 goto out_fput; 915 } 916 msg_ptr->m_ts = msg_len; 917 msg_ptr->m_type = msg_prio; 918 919 spin_lock(&info->lock); 920 921 if (info->attr.mq_curmsgs == info->attr.mq_maxmsg) { 922 if (filp->f_flags & O_NONBLOCK) { 923 spin_unlock(&info->lock); 924 ret = -EAGAIN; 925 } else { 926 wait.task = current; 927 wait.msg = (void *) msg_ptr; 928 wait.state = STATE_NONE; 929 ret = wq_sleep(info, SEND, timeout, &wait); 930 } 931 if (ret < 0) 932 free_msg(msg_ptr); 933 } else { 934 receiver = wq_get_first_waiter(info, RECV); 935 if (receiver) { 936 pipelined_send(info, msg_ptr, receiver); 937 } else { 938 /* adds message to the queue */ 939 msg_insert(msg_ptr, info); 940 __do_notify(info); 941 } 942 inode->i_atime = inode->i_mtime = inode->i_ctime = 943 CURRENT_TIME; 944 spin_unlock(&info->lock); 945 ret = 0; 946 } 947 out_fput: 948 fput(filp); 949 out: 950 return ret; 951 } 952 953 SYSCALL_DEFINE5(mq_timedreceive, mqd_t, mqdes, char __user *, u_msg_ptr, 954 size_t, msg_len, unsigned int __user *, u_msg_prio, 955 const struct timespec __user *, u_abs_timeout) 956 { 957 ssize_t ret; 958 struct msg_msg *msg_ptr; 959 struct file *filp; 960 struct inode *inode; 961 struct mqueue_inode_info *info; 962 struct ext_wait_queue wait; 963 ktime_t expires, *timeout = NULL; 964 struct timespec ts; 965 966 if (u_abs_timeout) { 967 int res = prepare_timeout(u_abs_timeout, &expires, &ts); 968 if (res) 969 return res; 970 timeout = &expires; 971 } 972 973 audit_mq_sendrecv(mqdes, msg_len, 0, timeout ? &ts : NULL); 974 975 filp = fget(mqdes); 976 if (unlikely(!filp)) { 977 ret = -EBADF; 978 goto out; 979 } 980 981 inode = filp->f_path.dentry->d_inode; 982 if (unlikely(filp->f_op != &mqueue_file_operations)) { 983 ret = -EBADF; 984 goto out_fput; 985 } 986 info = MQUEUE_I(inode); 987 audit_inode(NULL, filp->f_path.dentry); 988 989 if (unlikely(!(filp->f_mode & FMODE_READ))) { 990 ret = -EBADF; 991 goto out_fput; 992 } 993 994 /* checks if buffer is big enough */ 995 if (unlikely(msg_len < info->attr.mq_msgsize)) { 996 ret = -EMSGSIZE; 997 goto out_fput; 998 } 999 1000 spin_lock(&info->lock); 1001 if (info->attr.mq_curmsgs == 0) { 1002 if (filp->f_flags & O_NONBLOCK) { 1003 spin_unlock(&info->lock); 1004 ret = -EAGAIN; 1005 } else { 1006 wait.task = current; 1007 wait.state = STATE_NONE; 1008 ret = wq_sleep(info, RECV, timeout, &wait); 1009 msg_ptr = wait.msg; 1010 } 1011 } else { 1012 msg_ptr = msg_get(info); 1013 1014 inode->i_atime = inode->i_mtime = inode->i_ctime = 1015 CURRENT_TIME; 1016 1017 /* There is now free space in queue. */ 1018 pipelined_receive(info); 1019 spin_unlock(&info->lock); 1020 ret = 0; 1021 } 1022 if (ret == 0) { 1023 ret = msg_ptr->m_ts; 1024 1025 if ((u_msg_prio && put_user(msg_ptr->m_type, u_msg_prio)) || 1026 store_msg(u_msg_ptr, msg_ptr, msg_ptr->m_ts)) { 1027 ret = -EFAULT; 1028 } 1029 free_msg(msg_ptr); 1030 } 1031 out_fput: 1032 fput(filp); 1033 out: 1034 return ret; 1035 } 1036 1037 /* 1038 * Notes: the case when user wants us to deregister (with NULL as pointer) 1039 * and he isn't currently owner of notification, will be silently discarded. 1040 * It isn't explicitly defined in the POSIX. 1041 */ 1042 SYSCALL_DEFINE2(mq_notify, mqd_t, mqdes, 1043 const struct sigevent __user *, u_notification) 1044 { 1045 int ret; 1046 struct file *filp; 1047 struct sock *sock; 1048 struct inode *inode; 1049 struct sigevent notification; 1050 struct mqueue_inode_info *info; 1051 struct sk_buff *nc; 1052 1053 if (u_notification) { 1054 if (copy_from_user(¬ification, u_notification, 1055 sizeof(struct sigevent))) 1056 return -EFAULT; 1057 } 1058 1059 audit_mq_notify(mqdes, u_notification ? ¬ification : NULL); 1060 1061 nc = NULL; 1062 sock = NULL; 1063 if (u_notification != NULL) { 1064 if (unlikely(notification.sigev_notify != SIGEV_NONE && 1065 notification.sigev_notify != SIGEV_SIGNAL && 1066 notification.sigev_notify != SIGEV_THREAD)) 1067 return -EINVAL; 1068 if (notification.sigev_notify == SIGEV_SIGNAL && 1069 !valid_signal(notification.sigev_signo)) { 1070 return -EINVAL; 1071 } 1072 if (notification.sigev_notify == SIGEV_THREAD) { 1073 long timeo; 1074 1075 /* create the notify skb */ 1076 nc = alloc_skb(NOTIFY_COOKIE_LEN, GFP_KERNEL); 1077 if (!nc) { 1078 ret = -ENOMEM; 1079 goto out; 1080 } 1081 if (copy_from_user(nc->data, 1082 notification.sigev_value.sival_ptr, 1083 NOTIFY_COOKIE_LEN)) { 1084 ret = -EFAULT; 1085 goto out; 1086 } 1087 1088 /* TODO: add a header? */ 1089 skb_put(nc, NOTIFY_COOKIE_LEN); 1090 /* and attach it to the socket */ 1091 retry: 1092 filp = fget(notification.sigev_signo); 1093 if (!filp) { 1094 ret = -EBADF; 1095 goto out; 1096 } 1097 sock = netlink_getsockbyfilp(filp); 1098 fput(filp); 1099 if (IS_ERR(sock)) { 1100 ret = PTR_ERR(sock); 1101 sock = NULL; 1102 goto out; 1103 } 1104 1105 timeo = MAX_SCHEDULE_TIMEOUT; 1106 ret = netlink_attachskb(sock, nc, &timeo, NULL); 1107 if (ret == 1) 1108 goto retry; 1109 if (ret) { 1110 sock = NULL; 1111 nc = NULL; 1112 goto out; 1113 } 1114 } 1115 } 1116 1117 filp = fget(mqdes); 1118 if (!filp) { 1119 ret = -EBADF; 1120 goto out; 1121 } 1122 1123 inode = filp->f_path.dentry->d_inode; 1124 if (unlikely(filp->f_op != &mqueue_file_operations)) { 1125 ret = -EBADF; 1126 goto out_fput; 1127 } 1128 info = MQUEUE_I(inode); 1129 1130 ret = 0; 1131 spin_lock(&info->lock); 1132 if (u_notification == NULL) { 1133 if (info->notify_owner == task_tgid(current)) { 1134 remove_notification(info); 1135 inode->i_atime = inode->i_ctime = CURRENT_TIME; 1136 } 1137 } else if (info->notify_owner != NULL) { 1138 ret = -EBUSY; 1139 } else { 1140 switch (notification.sigev_notify) { 1141 case SIGEV_NONE: 1142 info->notify.sigev_notify = SIGEV_NONE; 1143 break; 1144 case SIGEV_THREAD: 1145 info->notify_sock = sock; 1146 info->notify_cookie = nc; 1147 sock = NULL; 1148 nc = NULL; 1149 info->notify.sigev_notify = SIGEV_THREAD; 1150 break; 1151 case SIGEV_SIGNAL: 1152 info->notify.sigev_signo = notification.sigev_signo; 1153 info->notify.sigev_value = notification.sigev_value; 1154 info->notify.sigev_notify = SIGEV_SIGNAL; 1155 break; 1156 } 1157 1158 info->notify_owner = get_pid(task_tgid(current)); 1159 info->notify_user_ns = get_user_ns(current_user_ns()); 1160 inode->i_atime = inode->i_ctime = CURRENT_TIME; 1161 } 1162 spin_unlock(&info->lock); 1163 out_fput: 1164 fput(filp); 1165 out: 1166 if (sock) { 1167 netlink_detachskb(sock, nc); 1168 } else if (nc) { 1169 dev_kfree_skb(nc); 1170 } 1171 return ret; 1172 } 1173 1174 SYSCALL_DEFINE3(mq_getsetattr, mqd_t, mqdes, 1175 const struct mq_attr __user *, u_mqstat, 1176 struct mq_attr __user *, u_omqstat) 1177 { 1178 int ret; 1179 struct mq_attr mqstat, omqstat; 1180 struct file *filp; 1181 struct inode *inode; 1182 struct mqueue_inode_info *info; 1183 1184 if (u_mqstat != NULL) { 1185 if (copy_from_user(&mqstat, u_mqstat, sizeof(struct mq_attr))) 1186 return -EFAULT; 1187 if (mqstat.mq_flags & (~O_NONBLOCK)) 1188 return -EINVAL; 1189 } 1190 1191 filp = fget(mqdes); 1192 if (!filp) { 1193 ret = -EBADF; 1194 goto out; 1195 } 1196 1197 inode = filp->f_path.dentry->d_inode; 1198 if (unlikely(filp->f_op != &mqueue_file_operations)) { 1199 ret = -EBADF; 1200 goto out_fput; 1201 } 1202 info = MQUEUE_I(inode); 1203 1204 spin_lock(&info->lock); 1205 1206 omqstat = info->attr; 1207 omqstat.mq_flags = filp->f_flags & O_NONBLOCK; 1208 if (u_mqstat) { 1209 audit_mq_getsetattr(mqdes, &mqstat); 1210 spin_lock(&filp->f_lock); 1211 if (mqstat.mq_flags & O_NONBLOCK) 1212 filp->f_flags |= O_NONBLOCK; 1213 else 1214 filp->f_flags &= ~O_NONBLOCK; 1215 spin_unlock(&filp->f_lock); 1216 1217 inode->i_atime = inode->i_ctime = CURRENT_TIME; 1218 } 1219 1220 spin_unlock(&info->lock); 1221 1222 ret = 0; 1223 if (u_omqstat != NULL && copy_to_user(u_omqstat, &omqstat, 1224 sizeof(struct mq_attr))) 1225 ret = -EFAULT; 1226 1227 out_fput: 1228 fput(filp); 1229 out: 1230 return ret; 1231 } 1232 1233 static const struct inode_operations mqueue_dir_inode_operations = { 1234 .lookup = simple_lookup, 1235 .create = mqueue_create, 1236 .unlink = mqueue_unlink, 1237 }; 1238 1239 static const struct file_operations mqueue_file_operations = { 1240 .flush = mqueue_flush_file, 1241 .poll = mqueue_poll_file, 1242 .read = mqueue_read_file, 1243 .llseek = default_llseek, 1244 }; 1245 1246 static const struct super_operations mqueue_super_ops = { 1247 .alloc_inode = mqueue_alloc_inode, 1248 .destroy_inode = mqueue_destroy_inode, 1249 .evict_inode = mqueue_evict_inode, 1250 .statfs = simple_statfs, 1251 }; 1252 1253 static struct file_system_type mqueue_fs_type = { 1254 .name = "mqueue", 1255 .mount = mqueue_mount, 1256 .kill_sb = kill_litter_super, 1257 }; 1258 1259 int mq_init_ns(struct ipc_namespace *ns) 1260 { 1261 ns->mq_queues_count = 0; 1262 ns->mq_queues_max = DFLT_QUEUESMAX; 1263 ns->mq_msg_max = DFLT_MSGMAX; 1264 ns->mq_msgsize_max = DFLT_MSGSIZEMAX; 1265 ns->mq_msg_default = DFLT_MSG; 1266 ns->mq_msgsize_default = DFLT_MSGSIZE; 1267 1268 ns->mq_mnt = kern_mount_data(&mqueue_fs_type, ns); 1269 if (IS_ERR(ns->mq_mnt)) { 1270 int err = PTR_ERR(ns->mq_mnt); 1271 ns->mq_mnt = NULL; 1272 return err; 1273 } 1274 return 0; 1275 } 1276 1277 void mq_clear_sbinfo(struct ipc_namespace *ns) 1278 { 1279 ns->mq_mnt->mnt_sb->s_fs_info = NULL; 1280 } 1281 1282 void mq_put_mnt(struct ipc_namespace *ns) 1283 { 1284 kern_unmount(ns->mq_mnt); 1285 } 1286 1287 static int __init init_mqueue_fs(void) 1288 { 1289 int error; 1290 1291 mqueue_inode_cachep = kmem_cache_create("mqueue_inode_cache", 1292 sizeof(struct mqueue_inode_info), 0, 1293 SLAB_HWCACHE_ALIGN, init_once); 1294 if (mqueue_inode_cachep == NULL) 1295 return -ENOMEM; 1296 1297 /* ignore failures - they are not fatal */ 1298 mq_sysctl_table = mq_register_sysctl_table(); 1299 1300 error = register_filesystem(&mqueue_fs_type); 1301 if (error) 1302 goto out_sysctl; 1303 1304 spin_lock_init(&mq_lock); 1305 1306 error = mq_init_ns(&init_ipc_ns); 1307 if (error) 1308 goto out_filesystem; 1309 1310 return 0; 1311 1312 out_filesystem: 1313 unregister_filesystem(&mqueue_fs_type); 1314 out_sysctl: 1315 if (mq_sysctl_table) 1316 unregister_sysctl_table(mq_sysctl_table); 1317 kmem_cache_destroy(mqueue_inode_cachep); 1318 return error; 1319 } 1320 1321 __initcall(init_mqueue_fs); 1322