mqueue.c revision fa0d7e3de6d6fc5004ad9dea0dd6b286af8f03e9
1/* 2 * POSIX message queues filesystem for Linux. 3 * 4 * Copyright (C) 2003,2004 Krzysztof Benedyczak (golbi@mat.uni.torun.pl) 5 * Michal Wronski (michal.wronski@gmail.com) 6 * 7 * Spinlocks: Mohamed Abbas (abbas.mohamed@intel.com) 8 * Lockless receive & send, fd based notify: 9 * Manfred Spraul (manfred@colorfullife.com) 10 * 11 * Audit: George Wilson (ltcgcw@us.ibm.com) 12 * 13 * This file is released under the GPL. 14 */ 15 16#include <linux/capability.h> 17#include <linux/init.h> 18#include <linux/pagemap.h> 19#include <linux/file.h> 20#include <linux/mount.h> 21#include <linux/namei.h> 22#include <linux/sysctl.h> 23#include <linux/poll.h> 24#include <linux/mqueue.h> 25#include <linux/msg.h> 26#include <linux/skbuff.h> 27#include <linux/netlink.h> 28#include <linux/syscalls.h> 29#include <linux/audit.h> 30#include <linux/signal.h> 31#include <linux/mutex.h> 32#include <linux/nsproxy.h> 33#include <linux/pid.h> 34#include <linux/ipc_namespace.h> 35#include <linux/slab.h> 36 37#include <net/sock.h> 38#include "util.h" 39 40#define MQUEUE_MAGIC 0x19800202 41#define DIRENT_SIZE 20 42#define FILENT_SIZE 80 43 44#define SEND 0 45#define RECV 1 46 47#define STATE_NONE 0 48#define STATE_PENDING 1 49#define STATE_READY 2 50 51struct ext_wait_queue { /* queue of sleeping tasks */ 52 struct task_struct *task; 53 struct list_head list; 54 struct msg_msg *msg; /* ptr of loaded message */ 55 int state; /* one of STATE_* values */ 56}; 57 58struct mqueue_inode_info { 59 spinlock_t lock; 60 struct inode vfs_inode; 61 wait_queue_head_t wait_q; 62 63 struct msg_msg **messages; 64 struct mq_attr attr; 65 66 struct sigevent notify; 67 struct pid* notify_owner; 68 struct user_struct *user; /* user who created, for accounting */ 69 struct sock *notify_sock; 70 struct sk_buff *notify_cookie; 71 72 /* for tasks waiting for free space and messages, respectively */ 73 struct ext_wait_queue e_wait_q[2]; 74 75 unsigned long qsize; /* size of queue in memory (sum of all msgs) */ 76}; 77 78static const struct inode_operations mqueue_dir_inode_operations; 79static const struct file_operations mqueue_file_operations; 80static const struct super_operations mqueue_super_ops; 81static void remove_notification(struct mqueue_inode_info *info); 82 83static struct kmem_cache *mqueue_inode_cachep; 84 85static struct ctl_table_header * mq_sysctl_table; 86 87static inline struct mqueue_inode_info *MQUEUE_I(struct inode *inode) 88{ 89 return container_of(inode, struct mqueue_inode_info, vfs_inode); 90} 91 92/* 93 * This routine should be called with the mq_lock held. 94 */ 95static inline struct ipc_namespace *__get_ns_from_inode(struct inode *inode) 96{ 97 return get_ipc_ns(inode->i_sb->s_fs_info); 98} 99 100static struct ipc_namespace *get_ns_from_inode(struct inode *inode) 101{ 102 struct ipc_namespace *ns; 103 104 spin_lock(&mq_lock); 105 ns = __get_ns_from_inode(inode); 106 spin_unlock(&mq_lock); 107 return ns; 108} 109 110static struct inode *mqueue_get_inode(struct super_block *sb, 111 struct ipc_namespace *ipc_ns, int mode, 112 struct mq_attr *attr) 113{ 114 struct user_struct *u = current_user(); 115 struct inode *inode; 116 117 inode = new_inode(sb); 118 if (inode) { 119 inode->i_ino = get_next_ino(); 120 inode->i_mode = mode; 121 inode->i_uid = current_fsuid(); 122 inode->i_gid = current_fsgid(); 123 inode->i_mtime = inode->i_ctime = inode->i_atime = 124 CURRENT_TIME; 125 126 if (S_ISREG(mode)) { 127 struct mqueue_inode_info *info; 128 struct task_struct *p = current; 129 unsigned long mq_bytes, mq_msg_tblsz; 130 131 inode->i_fop = &mqueue_file_operations; 132 inode->i_size = FILENT_SIZE; 133 /* mqueue specific info */ 134 info = MQUEUE_I(inode); 135 spin_lock_init(&info->lock); 136 init_waitqueue_head(&info->wait_q); 137 INIT_LIST_HEAD(&info->e_wait_q[0].list); 138 INIT_LIST_HEAD(&info->e_wait_q[1].list); 139 info->notify_owner = NULL; 140 info->qsize = 0; 141 info->user = NULL; /* set when all is ok */ 142 memset(&info->attr, 0, sizeof(info->attr)); 143 info->attr.mq_maxmsg = ipc_ns->mq_msg_max; 144 info->attr.mq_msgsize = ipc_ns->mq_msgsize_max; 145 if (attr) { 146 info->attr.mq_maxmsg = attr->mq_maxmsg; 147 info->attr.mq_msgsize = attr->mq_msgsize; 148 } 149 mq_msg_tblsz = info->attr.mq_maxmsg * sizeof(struct msg_msg *); 150 info->messages = kmalloc(mq_msg_tblsz, GFP_KERNEL); 151 if (!info->messages) 152 goto out_inode; 153 154 mq_bytes = (mq_msg_tblsz + 155 (info->attr.mq_maxmsg * info->attr.mq_msgsize)); 156 157 spin_lock(&mq_lock); 158 if (u->mq_bytes + mq_bytes < u->mq_bytes || 159 u->mq_bytes + mq_bytes > 160 task_rlimit(p, RLIMIT_MSGQUEUE)) { 161 spin_unlock(&mq_lock); 162 /* mqueue_evict_inode() releases info->messages */ 163 goto out_inode; 164 } 165 u->mq_bytes += mq_bytes; 166 spin_unlock(&mq_lock); 167 168 /* all is ok */ 169 info->user = get_uid(u); 170 } else if (S_ISDIR(mode)) { 171 inc_nlink(inode); 172 /* Some things misbehave if size == 0 on a directory */ 173 inode->i_size = 2 * DIRENT_SIZE; 174 inode->i_op = &mqueue_dir_inode_operations; 175 inode->i_fop = &simple_dir_operations; 176 } 177 } 178 return inode; 179out_inode: 180 iput(inode); 181 return NULL; 182} 183 184static int mqueue_fill_super(struct super_block *sb, void *data, int silent) 185{ 186 struct inode *inode; 187 struct ipc_namespace *ns = data; 188 int error; 189 190 sb->s_blocksize = PAGE_CACHE_SIZE; 191 sb->s_blocksize_bits = PAGE_CACHE_SHIFT; 192 sb->s_magic = MQUEUE_MAGIC; 193 sb->s_op = &mqueue_super_ops; 194 195 inode = mqueue_get_inode(sb, ns, S_IFDIR | S_ISVTX | S_IRWXUGO, 196 NULL); 197 if (!inode) { 198 error = -ENOMEM; 199 goto out; 200 } 201 202 sb->s_root = d_alloc_root(inode); 203 if (!sb->s_root) { 204 iput(inode); 205 error = -ENOMEM; 206 goto out; 207 } 208 error = 0; 209 210out: 211 return error; 212} 213 214static struct dentry *mqueue_mount(struct file_system_type *fs_type, 215 int flags, const char *dev_name, 216 void *data) 217{ 218 if (!(flags & MS_KERNMOUNT)) 219 data = current->nsproxy->ipc_ns; 220 return mount_ns(fs_type, flags, data, mqueue_fill_super); 221} 222 223static void init_once(void *foo) 224{ 225 struct mqueue_inode_info *p = (struct mqueue_inode_info *) foo; 226 227 inode_init_once(&p->vfs_inode); 228} 229 230static struct inode *mqueue_alloc_inode(struct super_block *sb) 231{ 232 struct mqueue_inode_info *ei; 233 234 ei = kmem_cache_alloc(mqueue_inode_cachep, GFP_KERNEL); 235 if (!ei) 236 return NULL; 237 return &ei->vfs_inode; 238} 239 240static void mqueue_i_callback(struct rcu_head *head) 241{ 242 struct inode *inode = container_of(head, struct inode, i_rcu); 243 INIT_LIST_HEAD(&inode->i_dentry); 244 kmem_cache_free(mqueue_inode_cachep, MQUEUE_I(inode)); 245} 246 247static void mqueue_destroy_inode(struct inode *inode) 248{ 249 call_rcu(&inode->i_rcu, mqueue_i_callback); 250} 251 252static 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 end_writeback(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 kfree(info->messages); 271 spin_unlock(&info->lock); 272 273 /* Total amount of bytes accounted for the mqueue */ 274 mq_bytes = info->attr.mq_maxmsg * (sizeof(struct msg_msg *) 275 + info->attr.mq_msgsize); 276 user = info->user; 277 if (user) { 278 spin_lock(&mq_lock); 279 user->mq_bytes -= mq_bytes; 280 /* 281 * get_ns_from_inode() ensures that the 282 * (ipc_ns = sb->s_fs_info) is either a valid ipc_ns 283 * to which we now hold a reference, or it is NULL. 284 * We can't put it here under mq_lock, though. 285 */ 286 if (ipc_ns) 287 ipc_ns->mq_queues_count--; 288 spin_unlock(&mq_lock); 289 free_uid(user); 290 } 291 if (ipc_ns) 292 put_ipc_ns(ipc_ns); 293} 294 295static int mqueue_create(struct inode *dir, struct dentry *dentry, 296 int mode, struct nameidata *nd) 297{ 298 struct inode *inode; 299 struct mq_attr *attr = dentry->d_fsdata; 300 int error; 301 struct ipc_namespace *ipc_ns; 302 303 spin_lock(&mq_lock); 304 ipc_ns = __get_ns_from_inode(dir); 305 if (!ipc_ns) { 306 error = -EACCES; 307 goto out_unlock; 308 } 309 if (ipc_ns->mq_queues_count >= ipc_ns->mq_queues_max && 310 !capable(CAP_SYS_RESOURCE)) { 311 error = -ENOSPC; 312 goto out_unlock; 313 } 314 ipc_ns->mq_queues_count++; 315 spin_unlock(&mq_lock); 316 317 inode = mqueue_get_inode(dir->i_sb, ipc_ns, mode, attr); 318 if (!inode) { 319 error = -ENOMEM; 320 spin_lock(&mq_lock); 321 ipc_ns->mq_queues_count--; 322 goto out_unlock; 323 } 324 325 put_ipc_ns(ipc_ns); 326 dir->i_size += DIRENT_SIZE; 327 dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME; 328 329 d_instantiate(dentry, inode); 330 dget(dentry); 331 return 0; 332out_unlock: 333 spin_unlock(&mq_lock); 334 if (ipc_ns) 335 put_ipc_ns(ipc_ns); 336 return error; 337} 338 339static int mqueue_unlink(struct inode *dir, struct dentry *dentry) 340{ 341 struct inode *inode = dentry->d_inode; 342 343 dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME; 344 dir->i_size -= DIRENT_SIZE; 345 drop_nlink(inode); 346 dput(dentry); 347 return 0; 348} 349 350/* 351* This is routine for system read from queue file. 352* To avoid mess with doing here some sort of mq_receive we allow 353* to read only queue size & notification info (the only values 354* that are interesting from user point of view and aren't accessible 355* through std routines) 356*/ 357static ssize_t mqueue_read_file(struct file *filp, char __user *u_data, 358 size_t count, loff_t *off) 359{ 360 struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode); 361 char buffer[FILENT_SIZE]; 362 ssize_t ret; 363 364 spin_lock(&info->lock); 365 snprintf(buffer, sizeof(buffer), 366 "QSIZE:%-10lu NOTIFY:%-5d SIGNO:%-5d NOTIFY_PID:%-6d\n", 367 info->qsize, 368 info->notify_owner ? info->notify.sigev_notify : 0, 369 (info->notify_owner && 370 info->notify.sigev_notify == SIGEV_SIGNAL) ? 371 info->notify.sigev_signo : 0, 372 pid_vnr(info->notify_owner)); 373 spin_unlock(&info->lock); 374 buffer[sizeof(buffer)-1] = '\0'; 375 376 ret = simple_read_from_buffer(u_data, count, off, buffer, 377 strlen(buffer)); 378 if (ret <= 0) 379 return ret; 380 381 filp->f_path.dentry->d_inode->i_atime = filp->f_path.dentry->d_inode->i_ctime = CURRENT_TIME; 382 return ret; 383} 384 385static int mqueue_flush_file(struct file *filp, fl_owner_t id) 386{ 387 struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode); 388 389 spin_lock(&info->lock); 390 if (task_tgid(current) == info->notify_owner) 391 remove_notification(info); 392 393 spin_unlock(&info->lock); 394 return 0; 395} 396 397static unsigned int mqueue_poll_file(struct file *filp, struct poll_table_struct *poll_tab) 398{ 399 struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode); 400 int retval = 0; 401 402 poll_wait(filp, &info->wait_q, poll_tab); 403 404 spin_lock(&info->lock); 405 if (info->attr.mq_curmsgs) 406 retval = POLLIN | POLLRDNORM; 407 408 if (info->attr.mq_curmsgs < info->attr.mq_maxmsg) 409 retval |= POLLOUT | POLLWRNORM; 410 spin_unlock(&info->lock); 411 412 return retval; 413} 414 415/* Adds current to info->e_wait_q[sr] before element with smaller prio */ 416static void wq_add(struct mqueue_inode_info *info, int sr, 417 struct ext_wait_queue *ewp) 418{ 419 struct ext_wait_queue *walk; 420 421 ewp->task = current; 422 423 list_for_each_entry(walk, &info->e_wait_q[sr].list, list) { 424 if (walk->task->static_prio <= current->static_prio) { 425 list_add_tail(&ewp->list, &walk->list); 426 return; 427 } 428 } 429 list_add_tail(&ewp->list, &info->e_wait_q[sr].list); 430} 431 432/* 433 * Puts current task to sleep. Caller must hold queue lock. After return 434 * lock isn't held. 435 * sr: SEND or RECV 436 */ 437static int wq_sleep(struct mqueue_inode_info *info, int sr, 438 ktime_t *timeout, struct ext_wait_queue *ewp) 439{ 440 int retval; 441 signed long time; 442 443 wq_add(info, sr, ewp); 444 445 for (;;) { 446 set_current_state(TASK_INTERRUPTIBLE); 447 448 spin_unlock(&info->lock); 449 time = schedule_hrtimeout_range_clock(timeout, 450 HRTIMER_MODE_ABS, 0, CLOCK_REALTIME); 451 452 while (ewp->state == STATE_PENDING) 453 cpu_relax(); 454 455 if (ewp->state == STATE_READY) { 456 retval = 0; 457 goto out; 458 } 459 spin_lock(&info->lock); 460 if (ewp->state == STATE_READY) { 461 retval = 0; 462 goto out_unlock; 463 } 464 if (signal_pending(current)) { 465 retval = -ERESTARTSYS; 466 break; 467 } 468 if (time == 0) { 469 retval = -ETIMEDOUT; 470 break; 471 } 472 } 473 list_del(&ewp->list); 474out_unlock: 475 spin_unlock(&info->lock); 476out: 477 return retval; 478} 479 480/* 481 * Returns waiting task that should be serviced first or NULL if none exists 482 */ 483static struct ext_wait_queue *wq_get_first_waiter( 484 struct mqueue_inode_info *info, int sr) 485{ 486 struct list_head *ptr; 487 488 ptr = info->e_wait_q[sr].list.prev; 489 if (ptr == &info->e_wait_q[sr].list) 490 return NULL; 491 return list_entry(ptr, struct ext_wait_queue, list); 492} 493 494/* Auxiliary functions to manipulate messages' list */ 495static void msg_insert(struct msg_msg *ptr, struct mqueue_inode_info *info) 496{ 497 int k; 498 499 k = info->attr.mq_curmsgs - 1; 500 while (k >= 0 && info->messages[k]->m_type >= ptr->m_type) { 501 info->messages[k + 1] = info->messages[k]; 502 k--; 503 } 504 info->attr.mq_curmsgs++; 505 info->qsize += ptr->m_ts; 506 info->messages[k + 1] = ptr; 507} 508 509static inline struct msg_msg *msg_get(struct mqueue_inode_info *info) 510{ 511 info->qsize -= info->messages[--info->attr.mq_curmsgs]->m_ts; 512 return info->messages[info->attr.mq_curmsgs]; 513} 514 515static inline void set_cookie(struct sk_buff *skb, char code) 516{ 517 ((char*)skb->data)[NOTIFY_COOKIE_LEN-1] = code; 518} 519 520/* 521 * The next function is only to split too long sys_mq_timedsend 522 */ 523static void __do_notify(struct mqueue_inode_info *info) 524{ 525 /* notification 526 * invoked when there is registered process and there isn't process 527 * waiting synchronously for message AND state of queue changed from 528 * empty to not empty. Here we are sure that no one is waiting 529 * synchronously. */ 530 if (info->notify_owner && 531 info->attr.mq_curmsgs == 1) { 532 struct siginfo sig_i; 533 switch (info->notify.sigev_notify) { 534 case SIGEV_NONE: 535 break; 536 case SIGEV_SIGNAL: 537 /* sends signal */ 538 539 sig_i.si_signo = info->notify.sigev_signo; 540 sig_i.si_errno = 0; 541 sig_i.si_code = SI_MESGQ; 542 sig_i.si_value = info->notify.sigev_value; 543 sig_i.si_pid = task_tgid_nr_ns(current, 544 ns_of_pid(info->notify_owner)); 545 sig_i.si_uid = current_uid(); 546 547 kill_pid_info(info->notify.sigev_signo, 548 &sig_i, info->notify_owner); 549 break; 550 case SIGEV_THREAD: 551 set_cookie(info->notify_cookie, NOTIFY_WOKENUP); 552 netlink_sendskb(info->notify_sock, info->notify_cookie); 553 break; 554 } 555 /* after notification unregisters process */ 556 put_pid(info->notify_owner); 557 info->notify_owner = NULL; 558 } 559 wake_up(&info->wait_q); 560} 561 562static int prepare_timeout(const struct timespec __user *u_abs_timeout, 563 ktime_t *expires, struct timespec *ts) 564{ 565 if (copy_from_user(ts, u_abs_timeout, sizeof(struct timespec))) 566 return -EFAULT; 567 if (!timespec_valid(ts)) 568 return -EINVAL; 569 570 *expires = timespec_to_ktime(*ts); 571 return 0; 572} 573 574static void remove_notification(struct mqueue_inode_info *info) 575{ 576 if (info->notify_owner != NULL && 577 info->notify.sigev_notify == SIGEV_THREAD) { 578 set_cookie(info->notify_cookie, NOTIFY_REMOVED); 579 netlink_sendskb(info->notify_sock, info->notify_cookie); 580 } 581 put_pid(info->notify_owner); 582 info->notify_owner = NULL; 583} 584 585static int mq_attr_ok(struct ipc_namespace *ipc_ns, struct mq_attr *attr) 586{ 587 if (attr->mq_maxmsg <= 0 || attr->mq_msgsize <= 0) 588 return 0; 589 if (capable(CAP_SYS_RESOURCE)) { 590 if (attr->mq_maxmsg > HARD_MSGMAX) 591 return 0; 592 } else { 593 if (attr->mq_maxmsg > ipc_ns->mq_msg_max || 594 attr->mq_msgsize > ipc_ns->mq_msgsize_max) 595 return 0; 596 } 597 /* check for overflow */ 598 if (attr->mq_msgsize > ULONG_MAX/attr->mq_maxmsg) 599 return 0; 600 if ((unsigned long)(attr->mq_maxmsg * (attr->mq_msgsize 601 + sizeof (struct msg_msg *))) < 602 (unsigned long)(attr->mq_maxmsg * attr->mq_msgsize)) 603 return 0; 604 return 1; 605} 606 607/* 608 * Invoked when creating a new queue via sys_mq_open 609 */ 610static struct file *do_create(struct ipc_namespace *ipc_ns, struct dentry *dir, 611 struct dentry *dentry, int oflag, mode_t mode, 612 struct mq_attr *attr) 613{ 614 const struct cred *cred = current_cred(); 615 struct file *result; 616 int ret; 617 618 if (attr) { 619 if (!mq_attr_ok(ipc_ns, attr)) { 620 ret = -EINVAL; 621 goto out; 622 } 623 /* store for use during create */ 624 dentry->d_fsdata = attr; 625 } 626 627 mode &= ~current_umask(); 628 ret = mnt_want_write(ipc_ns->mq_mnt); 629 if (ret) 630 goto out; 631 ret = vfs_create(dir->d_inode, dentry, mode, NULL); 632 dentry->d_fsdata = NULL; 633 if (ret) 634 goto out_drop_write; 635 636 result = dentry_open(dentry, ipc_ns->mq_mnt, oflag, cred); 637 /* 638 * dentry_open() took a persistent mnt_want_write(), 639 * so we can now drop this one. 640 */ 641 mnt_drop_write(ipc_ns->mq_mnt); 642 return result; 643 644out_drop_write: 645 mnt_drop_write(ipc_ns->mq_mnt); 646out: 647 dput(dentry); 648 mntput(ipc_ns->mq_mnt); 649 return ERR_PTR(ret); 650} 651 652/* Opens existing queue */ 653static struct file *do_open(struct ipc_namespace *ipc_ns, 654 struct dentry *dentry, int oflag) 655{ 656 int ret; 657 const struct cred *cred = current_cred(); 658 659 static const int oflag2acc[O_ACCMODE] = { MAY_READ, MAY_WRITE, 660 MAY_READ | MAY_WRITE }; 661 662 if ((oflag & O_ACCMODE) == (O_RDWR | O_WRONLY)) { 663 ret = -EINVAL; 664 goto err; 665 } 666 667 if (inode_permission(dentry->d_inode, oflag2acc[oflag & O_ACCMODE])) { 668 ret = -EACCES; 669 goto err; 670 } 671 672 return dentry_open(dentry, ipc_ns->mq_mnt, oflag, cred); 673 674err: 675 dput(dentry); 676 mntput(ipc_ns->mq_mnt); 677 return ERR_PTR(ret); 678} 679 680SYSCALL_DEFINE4(mq_open, const char __user *, u_name, int, oflag, mode_t, mode, 681 struct mq_attr __user *, u_attr) 682{ 683 struct dentry *dentry; 684 struct file *filp; 685 char *name; 686 struct mq_attr attr; 687 int fd, error; 688 struct ipc_namespace *ipc_ns = current->nsproxy->ipc_ns; 689 690 if (u_attr && copy_from_user(&attr, u_attr, sizeof(struct mq_attr))) 691 return -EFAULT; 692 693 audit_mq_open(oflag, mode, u_attr ? &attr : NULL); 694 695 if (IS_ERR(name = getname(u_name))) 696 return PTR_ERR(name); 697 698 fd = get_unused_fd_flags(O_CLOEXEC); 699 if (fd < 0) 700 goto out_putname; 701 702 mutex_lock(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex); 703 dentry = lookup_one_len(name, ipc_ns->mq_mnt->mnt_root, strlen(name)); 704 if (IS_ERR(dentry)) { 705 error = PTR_ERR(dentry); 706 goto out_putfd; 707 } 708 mntget(ipc_ns->mq_mnt); 709 710 if (oflag & O_CREAT) { 711 if (dentry->d_inode) { /* entry already exists */ 712 audit_inode(name, dentry); 713 if (oflag & O_EXCL) { 714 error = -EEXIST; 715 goto out; 716 } 717 filp = do_open(ipc_ns, dentry, oflag); 718 } else { 719 filp = do_create(ipc_ns, ipc_ns->mq_mnt->mnt_root, 720 dentry, oflag, mode, 721 u_attr ? &attr : NULL); 722 } 723 } else { 724 if (!dentry->d_inode) { 725 error = -ENOENT; 726 goto out; 727 } 728 audit_inode(name, dentry); 729 filp = do_open(ipc_ns, dentry, oflag); 730 } 731 732 if (IS_ERR(filp)) { 733 error = PTR_ERR(filp); 734 goto out_putfd; 735 } 736 737 fd_install(fd, filp); 738 goto out_upsem; 739 740out: 741 dput(dentry); 742 mntput(ipc_ns->mq_mnt); 743out_putfd: 744 put_unused_fd(fd); 745 fd = error; 746out_upsem: 747 mutex_unlock(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex); 748out_putname: 749 putname(name); 750 return fd; 751} 752 753SYSCALL_DEFINE1(mq_unlink, const char __user *, u_name) 754{ 755 int err; 756 char *name; 757 struct dentry *dentry; 758 struct inode *inode = NULL; 759 struct ipc_namespace *ipc_ns = current->nsproxy->ipc_ns; 760 761 name = getname(u_name); 762 if (IS_ERR(name)) 763 return PTR_ERR(name); 764 765 mutex_lock_nested(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex, 766 I_MUTEX_PARENT); 767 dentry = lookup_one_len(name, ipc_ns->mq_mnt->mnt_root, strlen(name)); 768 if (IS_ERR(dentry)) { 769 err = PTR_ERR(dentry); 770 goto out_unlock; 771 } 772 773 if (!dentry->d_inode) { 774 err = -ENOENT; 775 goto out_err; 776 } 777 778 inode = dentry->d_inode; 779 if (inode) 780 ihold(inode); 781 err = mnt_want_write(ipc_ns->mq_mnt); 782 if (err) 783 goto out_err; 784 err = vfs_unlink(dentry->d_parent->d_inode, dentry); 785 mnt_drop_write(ipc_ns->mq_mnt); 786out_err: 787 dput(dentry); 788 789out_unlock: 790 mutex_unlock(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex); 791 putname(name); 792 if (inode) 793 iput(inode); 794 795 return err; 796} 797 798/* Pipelined send and receive functions. 799 * 800 * If a receiver finds no waiting message, then it registers itself in the 801 * list of waiting receivers. A sender checks that list before adding the new 802 * message into the message array. If there is a waiting receiver, then it 803 * bypasses the message array and directly hands the message over to the 804 * receiver. 805 * The receiver accepts the message and returns without grabbing the queue 806 * spinlock. Therefore an intermediate STATE_PENDING state and memory barriers 807 * are necessary. The same algorithm is used for sysv semaphores, see 808 * ipc/sem.c for more details. 809 * 810 * The same algorithm is used for senders. 811 */ 812 813/* pipelined_send() - send a message directly to the task waiting in 814 * sys_mq_timedreceive() (without inserting message into a queue). 815 */ 816static inline void pipelined_send(struct mqueue_inode_info *info, 817 struct msg_msg *message, 818 struct ext_wait_queue *receiver) 819{ 820 receiver->msg = message; 821 list_del(&receiver->list); 822 receiver->state = STATE_PENDING; 823 wake_up_process(receiver->task); 824 smp_wmb(); 825 receiver->state = STATE_READY; 826} 827 828/* pipelined_receive() - if there is task waiting in sys_mq_timedsend() 829 * gets its message and put to the queue (we have one free place for sure). */ 830static inline void pipelined_receive(struct mqueue_inode_info *info) 831{ 832 struct ext_wait_queue *sender = wq_get_first_waiter(info, SEND); 833 834 if (!sender) { 835 /* for poll */ 836 wake_up_interruptible(&info->wait_q); 837 return; 838 } 839 msg_insert(sender->msg, info); 840 list_del(&sender->list); 841 sender->state = STATE_PENDING; 842 wake_up_process(sender->task); 843 smp_wmb(); 844 sender->state = STATE_READY; 845} 846 847SYSCALL_DEFINE5(mq_timedsend, mqd_t, mqdes, const char __user *, u_msg_ptr, 848 size_t, msg_len, unsigned int, msg_prio, 849 const struct timespec __user *, u_abs_timeout) 850{ 851 struct file *filp; 852 struct inode *inode; 853 struct ext_wait_queue wait; 854 struct ext_wait_queue *receiver; 855 struct msg_msg *msg_ptr; 856 struct mqueue_inode_info *info; 857 ktime_t expires, *timeout = NULL; 858 struct timespec ts; 859 int ret; 860 861 if (u_abs_timeout) { 862 int res = prepare_timeout(u_abs_timeout, &expires, &ts); 863 if (res) 864 return res; 865 timeout = &expires; 866 } 867 868 if (unlikely(msg_prio >= (unsigned long) MQ_PRIO_MAX)) 869 return -EINVAL; 870 871 audit_mq_sendrecv(mqdes, msg_len, msg_prio, timeout ? &ts : NULL); 872 873 filp = fget(mqdes); 874 if (unlikely(!filp)) { 875 ret = -EBADF; 876 goto out; 877 } 878 879 inode = filp->f_path.dentry->d_inode; 880 if (unlikely(filp->f_op != &mqueue_file_operations)) { 881 ret = -EBADF; 882 goto out_fput; 883 } 884 info = MQUEUE_I(inode); 885 audit_inode(NULL, filp->f_path.dentry); 886 887 if (unlikely(!(filp->f_mode & FMODE_WRITE))) { 888 ret = -EBADF; 889 goto out_fput; 890 } 891 892 if (unlikely(msg_len > info->attr.mq_msgsize)) { 893 ret = -EMSGSIZE; 894 goto out_fput; 895 } 896 897 /* First try to allocate memory, before doing anything with 898 * existing queues. */ 899 msg_ptr = load_msg(u_msg_ptr, msg_len); 900 if (IS_ERR(msg_ptr)) { 901 ret = PTR_ERR(msg_ptr); 902 goto out_fput; 903 } 904 msg_ptr->m_ts = msg_len; 905 msg_ptr->m_type = msg_prio; 906 907 spin_lock(&info->lock); 908 909 if (info->attr.mq_curmsgs == info->attr.mq_maxmsg) { 910 if (filp->f_flags & O_NONBLOCK) { 911 spin_unlock(&info->lock); 912 ret = -EAGAIN; 913 } else { 914 wait.task = current; 915 wait.msg = (void *) msg_ptr; 916 wait.state = STATE_NONE; 917 ret = wq_sleep(info, SEND, timeout, &wait); 918 } 919 if (ret < 0) 920 free_msg(msg_ptr); 921 } else { 922 receiver = wq_get_first_waiter(info, RECV); 923 if (receiver) { 924 pipelined_send(info, msg_ptr, receiver); 925 } else { 926 /* adds message to the queue */ 927 msg_insert(msg_ptr, info); 928 __do_notify(info); 929 } 930 inode->i_atime = inode->i_mtime = inode->i_ctime = 931 CURRENT_TIME; 932 spin_unlock(&info->lock); 933 ret = 0; 934 } 935out_fput: 936 fput(filp); 937out: 938 return ret; 939} 940 941SYSCALL_DEFINE5(mq_timedreceive, mqd_t, mqdes, char __user *, u_msg_ptr, 942 size_t, msg_len, unsigned int __user *, u_msg_prio, 943 const struct timespec __user *, u_abs_timeout) 944{ 945 ssize_t ret; 946 struct msg_msg *msg_ptr; 947 struct file *filp; 948 struct inode *inode; 949 struct mqueue_inode_info *info; 950 struct ext_wait_queue wait; 951 ktime_t expires, *timeout = NULL; 952 struct timespec ts; 953 954 if (u_abs_timeout) { 955 int res = prepare_timeout(u_abs_timeout, &expires, &ts); 956 if (res) 957 return res; 958 timeout = &expires; 959 } 960 961 audit_mq_sendrecv(mqdes, msg_len, 0, timeout ? &ts : NULL); 962 963 filp = fget(mqdes); 964 if (unlikely(!filp)) { 965 ret = -EBADF; 966 goto out; 967 } 968 969 inode = filp->f_path.dentry->d_inode; 970 if (unlikely(filp->f_op != &mqueue_file_operations)) { 971 ret = -EBADF; 972 goto out_fput; 973 } 974 info = MQUEUE_I(inode); 975 audit_inode(NULL, filp->f_path.dentry); 976 977 if (unlikely(!(filp->f_mode & FMODE_READ))) { 978 ret = -EBADF; 979 goto out_fput; 980 } 981 982 /* checks if buffer is big enough */ 983 if (unlikely(msg_len < info->attr.mq_msgsize)) { 984 ret = -EMSGSIZE; 985 goto out_fput; 986 } 987 988 spin_lock(&info->lock); 989 if (info->attr.mq_curmsgs == 0) { 990 if (filp->f_flags & O_NONBLOCK) { 991 spin_unlock(&info->lock); 992 ret = -EAGAIN; 993 } else { 994 wait.task = current; 995 wait.state = STATE_NONE; 996 ret = wq_sleep(info, RECV, timeout, &wait); 997 msg_ptr = wait.msg; 998 } 999 } else { 1000 msg_ptr = msg_get(info); 1001 1002 inode->i_atime = inode->i_mtime = inode->i_ctime = 1003 CURRENT_TIME; 1004 1005 /* There is now free space in queue. */ 1006 pipelined_receive(info); 1007 spin_unlock(&info->lock); 1008 ret = 0; 1009 } 1010 if (ret == 0) { 1011 ret = msg_ptr->m_ts; 1012 1013 if ((u_msg_prio && put_user(msg_ptr->m_type, u_msg_prio)) || 1014 store_msg(u_msg_ptr, msg_ptr, msg_ptr->m_ts)) { 1015 ret = -EFAULT; 1016 } 1017 free_msg(msg_ptr); 1018 } 1019out_fput: 1020 fput(filp); 1021out: 1022 return ret; 1023} 1024 1025/* 1026 * Notes: the case when user wants us to deregister (with NULL as pointer) 1027 * and he isn't currently owner of notification, will be silently discarded. 1028 * It isn't explicitly defined in the POSIX. 1029 */ 1030SYSCALL_DEFINE2(mq_notify, mqd_t, mqdes, 1031 const struct sigevent __user *, u_notification) 1032{ 1033 int ret; 1034 struct file *filp; 1035 struct sock *sock; 1036 struct inode *inode; 1037 struct sigevent notification; 1038 struct mqueue_inode_info *info; 1039 struct sk_buff *nc; 1040 1041 if (u_notification) { 1042 if (copy_from_user(¬ification, u_notification, 1043 sizeof(struct sigevent))) 1044 return -EFAULT; 1045 } 1046 1047 audit_mq_notify(mqdes, u_notification ? ¬ification : NULL); 1048 1049 nc = NULL; 1050 sock = NULL; 1051 if (u_notification != NULL) { 1052 if (unlikely(notification.sigev_notify != SIGEV_NONE && 1053 notification.sigev_notify != SIGEV_SIGNAL && 1054 notification.sigev_notify != SIGEV_THREAD)) 1055 return -EINVAL; 1056 if (notification.sigev_notify == SIGEV_SIGNAL && 1057 !valid_signal(notification.sigev_signo)) { 1058 return -EINVAL; 1059 } 1060 if (notification.sigev_notify == SIGEV_THREAD) { 1061 long timeo; 1062 1063 /* create the notify skb */ 1064 nc = alloc_skb(NOTIFY_COOKIE_LEN, GFP_KERNEL); 1065 if (!nc) { 1066 ret = -ENOMEM; 1067 goto out; 1068 } 1069 if (copy_from_user(nc->data, 1070 notification.sigev_value.sival_ptr, 1071 NOTIFY_COOKIE_LEN)) { 1072 ret = -EFAULT; 1073 goto out; 1074 } 1075 1076 /* TODO: add a header? */ 1077 skb_put(nc, NOTIFY_COOKIE_LEN); 1078 /* and attach it to the socket */ 1079retry: 1080 filp = fget(notification.sigev_signo); 1081 if (!filp) { 1082 ret = -EBADF; 1083 goto out; 1084 } 1085 sock = netlink_getsockbyfilp(filp); 1086 fput(filp); 1087 if (IS_ERR(sock)) { 1088 ret = PTR_ERR(sock); 1089 sock = NULL; 1090 goto out; 1091 } 1092 1093 timeo = MAX_SCHEDULE_TIMEOUT; 1094 ret = netlink_attachskb(sock, nc, &timeo, NULL); 1095 if (ret == 1) 1096 goto retry; 1097 if (ret) { 1098 sock = NULL; 1099 nc = NULL; 1100 goto out; 1101 } 1102 } 1103 } 1104 1105 filp = fget(mqdes); 1106 if (!filp) { 1107 ret = -EBADF; 1108 goto out; 1109 } 1110 1111 inode = filp->f_path.dentry->d_inode; 1112 if (unlikely(filp->f_op != &mqueue_file_operations)) { 1113 ret = -EBADF; 1114 goto out_fput; 1115 } 1116 info = MQUEUE_I(inode); 1117 1118 ret = 0; 1119 spin_lock(&info->lock); 1120 if (u_notification == NULL) { 1121 if (info->notify_owner == task_tgid(current)) { 1122 remove_notification(info); 1123 inode->i_atime = inode->i_ctime = CURRENT_TIME; 1124 } 1125 } else if (info->notify_owner != NULL) { 1126 ret = -EBUSY; 1127 } else { 1128 switch (notification.sigev_notify) { 1129 case SIGEV_NONE: 1130 info->notify.sigev_notify = SIGEV_NONE; 1131 break; 1132 case SIGEV_THREAD: 1133 info->notify_sock = sock; 1134 info->notify_cookie = nc; 1135 sock = NULL; 1136 nc = NULL; 1137 info->notify.sigev_notify = SIGEV_THREAD; 1138 break; 1139 case SIGEV_SIGNAL: 1140 info->notify.sigev_signo = notification.sigev_signo; 1141 info->notify.sigev_value = notification.sigev_value; 1142 info->notify.sigev_notify = SIGEV_SIGNAL; 1143 break; 1144 } 1145 1146 info->notify_owner = get_pid(task_tgid(current)); 1147 inode->i_atime = inode->i_ctime = CURRENT_TIME; 1148 } 1149 spin_unlock(&info->lock); 1150out_fput: 1151 fput(filp); 1152out: 1153 if (sock) { 1154 netlink_detachskb(sock, nc); 1155 } else if (nc) { 1156 dev_kfree_skb(nc); 1157 } 1158 return ret; 1159} 1160 1161SYSCALL_DEFINE3(mq_getsetattr, mqd_t, mqdes, 1162 const struct mq_attr __user *, u_mqstat, 1163 struct mq_attr __user *, u_omqstat) 1164{ 1165 int ret; 1166 struct mq_attr mqstat, omqstat; 1167 struct file *filp; 1168 struct inode *inode; 1169 struct mqueue_inode_info *info; 1170 1171 if (u_mqstat != NULL) { 1172 if (copy_from_user(&mqstat, u_mqstat, sizeof(struct mq_attr))) 1173 return -EFAULT; 1174 if (mqstat.mq_flags & (~O_NONBLOCK)) 1175 return -EINVAL; 1176 } 1177 1178 filp = fget(mqdes); 1179 if (!filp) { 1180 ret = -EBADF; 1181 goto out; 1182 } 1183 1184 inode = filp->f_path.dentry->d_inode; 1185 if (unlikely(filp->f_op != &mqueue_file_operations)) { 1186 ret = -EBADF; 1187 goto out_fput; 1188 } 1189 info = MQUEUE_I(inode); 1190 1191 spin_lock(&info->lock); 1192 1193 omqstat = info->attr; 1194 omqstat.mq_flags = filp->f_flags & O_NONBLOCK; 1195 if (u_mqstat) { 1196 audit_mq_getsetattr(mqdes, &mqstat); 1197 spin_lock(&filp->f_lock); 1198 if (mqstat.mq_flags & O_NONBLOCK) 1199 filp->f_flags |= O_NONBLOCK; 1200 else 1201 filp->f_flags &= ~O_NONBLOCK; 1202 spin_unlock(&filp->f_lock); 1203 1204 inode->i_atime = inode->i_ctime = CURRENT_TIME; 1205 } 1206 1207 spin_unlock(&info->lock); 1208 1209 ret = 0; 1210 if (u_omqstat != NULL && copy_to_user(u_omqstat, &omqstat, 1211 sizeof(struct mq_attr))) 1212 ret = -EFAULT; 1213 1214out_fput: 1215 fput(filp); 1216out: 1217 return ret; 1218} 1219 1220static const struct inode_operations mqueue_dir_inode_operations = { 1221 .lookup = simple_lookup, 1222 .create = mqueue_create, 1223 .unlink = mqueue_unlink, 1224}; 1225 1226static const struct file_operations mqueue_file_operations = { 1227 .flush = mqueue_flush_file, 1228 .poll = mqueue_poll_file, 1229 .read = mqueue_read_file, 1230 .llseek = default_llseek, 1231}; 1232 1233static const struct super_operations mqueue_super_ops = { 1234 .alloc_inode = mqueue_alloc_inode, 1235 .destroy_inode = mqueue_destroy_inode, 1236 .evict_inode = mqueue_evict_inode, 1237 .statfs = simple_statfs, 1238}; 1239 1240static struct file_system_type mqueue_fs_type = { 1241 .name = "mqueue", 1242 .mount = mqueue_mount, 1243 .kill_sb = kill_litter_super, 1244}; 1245 1246int mq_init_ns(struct ipc_namespace *ns) 1247{ 1248 ns->mq_queues_count = 0; 1249 ns->mq_queues_max = DFLT_QUEUESMAX; 1250 ns->mq_msg_max = DFLT_MSGMAX; 1251 ns->mq_msgsize_max = DFLT_MSGSIZEMAX; 1252 1253 ns->mq_mnt = kern_mount_data(&mqueue_fs_type, ns); 1254 if (IS_ERR(ns->mq_mnt)) { 1255 int err = PTR_ERR(ns->mq_mnt); 1256 ns->mq_mnt = NULL; 1257 return err; 1258 } 1259 return 0; 1260} 1261 1262void mq_clear_sbinfo(struct ipc_namespace *ns) 1263{ 1264 ns->mq_mnt->mnt_sb->s_fs_info = NULL; 1265} 1266 1267void mq_put_mnt(struct ipc_namespace *ns) 1268{ 1269 mntput(ns->mq_mnt); 1270} 1271 1272static int __init init_mqueue_fs(void) 1273{ 1274 int error; 1275 1276 mqueue_inode_cachep = kmem_cache_create("mqueue_inode_cache", 1277 sizeof(struct mqueue_inode_info), 0, 1278 SLAB_HWCACHE_ALIGN, init_once); 1279 if (mqueue_inode_cachep == NULL) 1280 return -ENOMEM; 1281 1282 /* ignore failures - they are not fatal */ 1283 mq_sysctl_table = mq_register_sysctl_table(); 1284 1285 error = register_filesystem(&mqueue_fs_type); 1286 if (error) 1287 goto out_sysctl; 1288 1289 spin_lock_init(&mq_lock); 1290 1291 init_ipc_ns.mq_mnt = kern_mount_data(&mqueue_fs_type, &init_ipc_ns); 1292 if (IS_ERR(init_ipc_ns.mq_mnt)) { 1293 error = PTR_ERR(init_ipc_ns.mq_mnt); 1294 goto out_filesystem; 1295 } 1296 1297 return 0; 1298 1299out_filesystem: 1300 unregister_filesystem(&mqueue_fs_type); 1301out_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