mqueue.c revision df0a42837b86567a130c44515ab620d23e7f182b
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, umode_t mode, 112 struct mq_attr *attr) 113{ 114 struct user_struct *u = current_user(); 115 struct inode *inode; 116 int ret = -ENOMEM; 117 118 inode = new_inode(sb); 119 if (!inode) 120 goto err; 121 122 inode->i_ino = get_next_ino(); 123 inode->i_mode = mode; 124 inode->i_uid = current_fsuid(); 125 inode->i_gid = current_fsgid(); 126 inode->i_mtime = inode->i_ctime = inode->i_atime = CURRENT_TIME; 127 128 if (S_ISREG(mode)) { 129 struct mqueue_inode_info *info; 130 struct task_struct *p = current; 131 unsigned long mq_bytes, mq_msg_tblsz; 132 133 inode->i_fop = &mqueue_file_operations; 134 inode->i_size = FILENT_SIZE; 135 /* mqueue specific info */ 136 info = MQUEUE_I(inode); 137 spin_lock_init(&info->lock); 138 init_waitqueue_head(&info->wait_q); 139 INIT_LIST_HEAD(&info->e_wait_q[0].list); 140 INIT_LIST_HEAD(&info->e_wait_q[1].list); 141 info->notify_owner = NULL; 142 info->qsize = 0; 143 info->user = NULL; /* set when all is ok */ 144 memset(&info->attr, 0, sizeof(info->attr)); 145 info->attr.mq_maxmsg = ipc_ns->mq_msg_max; 146 info->attr.mq_msgsize = ipc_ns->mq_msgsize_max; 147 if (attr) { 148 info->attr.mq_maxmsg = attr->mq_maxmsg; 149 info->attr.mq_msgsize = attr->mq_msgsize; 150 } 151 mq_msg_tblsz = info->attr.mq_maxmsg * sizeof(struct msg_msg *); 152 info->messages = kmalloc(mq_msg_tblsz, GFP_KERNEL); 153 if (!info->messages) 154 goto out_inode; 155 156 mq_bytes = (mq_msg_tblsz + 157 (info->attr.mq_maxmsg * info->attr.mq_msgsize)); 158 159 spin_lock(&mq_lock); 160 if (u->mq_bytes + mq_bytes < u->mq_bytes || 161 u->mq_bytes + mq_bytes > task_rlimit(p, RLIMIT_MSGQUEUE)) { 162 spin_unlock(&mq_lock); 163 /* mqueue_evict_inode() releases info->messages */ 164 ret = -EMFILE; 165 goto out_inode; 166 } 167 u->mq_bytes += mq_bytes; 168 spin_unlock(&mq_lock); 169 170 /* all is ok */ 171 info->user = get_uid(u); 172 } else if (S_ISDIR(mode)) { 173 inc_nlink(inode); 174 /* Some things misbehave if size == 0 on a directory */ 175 inode->i_size = 2 * DIRENT_SIZE; 176 inode->i_op = &mqueue_dir_inode_operations; 177 inode->i_fop = &simple_dir_operations; 178 } 179 180 return inode; 181out_inode: 182 iput(inode); 183err: 184 return ERR_PTR(ret); 185} 186 187static int mqueue_fill_super(struct super_block *sb, void *data, int silent) 188{ 189 struct inode *inode; 190 struct ipc_namespace *ns = data; 191 int error; 192 193 sb->s_blocksize = PAGE_CACHE_SIZE; 194 sb->s_blocksize_bits = PAGE_CACHE_SHIFT; 195 sb->s_magic = MQUEUE_MAGIC; 196 sb->s_op = &mqueue_super_ops; 197 198 inode = mqueue_get_inode(sb, ns, S_IFDIR | S_ISVTX | S_IRWXUGO, 199 NULL); 200 if (IS_ERR(inode)) { 201 error = PTR_ERR(inode); 202 goto out; 203 } 204 205 sb->s_root = d_alloc_root(inode); 206 if (!sb->s_root) { 207 iput(inode); 208 error = -ENOMEM; 209 goto out; 210 } 211 error = 0; 212 213out: 214 return error; 215} 216 217static struct dentry *mqueue_mount(struct file_system_type *fs_type, 218 int flags, const char *dev_name, 219 void *data) 220{ 221 if (!(flags & MS_KERNMOUNT)) 222 data = current->nsproxy->ipc_ns; 223 return mount_ns(fs_type, flags, data, mqueue_fill_super); 224} 225 226static void init_once(void *foo) 227{ 228 struct mqueue_inode_info *p = (struct mqueue_inode_info *) foo; 229 230 inode_init_once(&p->vfs_inode); 231} 232 233static struct inode *mqueue_alloc_inode(struct super_block *sb) 234{ 235 struct mqueue_inode_info *ei; 236 237 ei = kmem_cache_alloc(mqueue_inode_cachep, GFP_KERNEL); 238 if (!ei) 239 return NULL; 240 return &ei->vfs_inode; 241} 242 243static void mqueue_i_callback(struct rcu_head *head) 244{ 245 struct inode *inode = container_of(head, struct inode, i_rcu); 246 kmem_cache_free(mqueue_inode_cachep, MQUEUE_I(inode)); 247} 248 249static void mqueue_destroy_inode(struct inode *inode) 250{ 251 call_rcu(&inode->i_rcu, mqueue_i_callback); 252} 253 254static void mqueue_evict_inode(struct inode *inode) 255{ 256 struct mqueue_inode_info *info; 257 struct user_struct *user; 258 unsigned long mq_bytes; 259 int i; 260 struct ipc_namespace *ipc_ns; 261 262 end_writeback(inode); 263 264 if (S_ISDIR(inode->i_mode)) 265 return; 266 267 ipc_ns = get_ns_from_inode(inode); 268 info = MQUEUE_I(inode); 269 spin_lock(&info->lock); 270 for (i = 0; i < info->attr.mq_curmsgs; i++) 271 free_msg(info->messages[i]); 272 kfree(info->messages); 273 spin_unlock(&info->lock); 274 275 /* Total amount of bytes accounted for the mqueue */ 276 mq_bytes = info->attr.mq_maxmsg * (sizeof(struct msg_msg *) 277 + info->attr.mq_msgsize); 278 user = info->user; 279 if (user) { 280 spin_lock(&mq_lock); 281 user->mq_bytes -= mq_bytes; 282 /* 283 * get_ns_from_inode() ensures that the 284 * (ipc_ns = sb->s_fs_info) is either a valid ipc_ns 285 * to which we now hold a reference, or it is NULL. 286 * We can't put it here under mq_lock, though. 287 */ 288 if (ipc_ns) 289 ipc_ns->mq_queues_count--; 290 spin_unlock(&mq_lock); 291 free_uid(user); 292 } 293 if (ipc_ns) 294 put_ipc_ns(ipc_ns); 295} 296 297static int mqueue_create(struct inode *dir, struct dentry *dentry, 298 umode_t mode, struct nameidata *nd) 299{ 300 struct inode *inode; 301 struct mq_attr *attr = dentry->d_fsdata; 302 int error; 303 struct ipc_namespace *ipc_ns; 304 305 spin_lock(&mq_lock); 306 ipc_ns = __get_ns_from_inode(dir); 307 if (!ipc_ns) { 308 error = -EACCES; 309 goto out_unlock; 310 } 311 if (ipc_ns->mq_queues_count >= ipc_ns->mq_queues_max && 312 !capable(CAP_SYS_RESOURCE)) { 313 error = -ENOSPC; 314 goto out_unlock; 315 } 316 ipc_ns->mq_queues_count++; 317 spin_unlock(&mq_lock); 318 319 inode = mqueue_get_inode(dir->i_sb, ipc_ns, mode, attr); 320 if (IS_ERR(inode)) { 321 error = PTR_ERR(inode); 322 spin_lock(&mq_lock); 323 ipc_ns->mq_queues_count--; 324 goto out_unlock; 325 } 326 327 put_ipc_ns(ipc_ns); 328 dir->i_size += DIRENT_SIZE; 329 dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME; 330 331 d_instantiate(dentry, inode); 332 dget(dentry); 333 return 0; 334out_unlock: 335 spin_unlock(&mq_lock); 336 if (ipc_ns) 337 put_ipc_ns(ipc_ns); 338 return error; 339} 340 341static int mqueue_unlink(struct inode *dir, struct dentry *dentry) 342{ 343 struct inode *inode = dentry->d_inode; 344 345 dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME; 346 dir->i_size -= DIRENT_SIZE; 347 drop_nlink(inode); 348 dput(dentry); 349 return 0; 350} 351 352/* 353* This is routine for system read from queue file. 354* To avoid mess with doing here some sort of mq_receive we allow 355* to read only queue size & notification info (the only values 356* that are interesting from user point of view and aren't accessible 357* through std routines) 358*/ 359static ssize_t mqueue_read_file(struct file *filp, char __user *u_data, 360 size_t count, loff_t *off) 361{ 362 struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode); 363 char buffer[FILENT_SIZE]; 364 ssize_t ret; 365 366 spin_lock(&info->lock); 367 snprintf(buffer, sizeof(buffer), 368 "QSIZE:%-10lu NOTIFY:%-5d SIGNO:%-5d NOTIFY_PID:%-6d\n", 369 info->qsize, 370 info->notify_owner ? info->notify.sigev_notify : 0, 371 (info->notify_owner && 372 info->notify.sigev_notify == SIGEV_SIGNAL) ? 373 info->notify.sigev_signo : 0, 374 pid_vnr(info->notify_owner)); 375 spin_unlock(&info->lock); 376 buffer[sizeof(buffer)-1] = '\0'; 377 378 ret = simple_read_from_buffer(u_data, count, off, buffer, 379 strlen(buffer)); 380 if (ret <= 0) 381 return ret; 382 383 filp->f_path.dentry->d_inode->i_atime = filp->f_path.dentry->d_inode->i_ctime = CURRENT_TIME; 384 return ret; 385} 386 387static int mqueue_flush_file(struct file *filp, fl_owner_t id) 388{ 389 struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode); 390 391 spin_lock(&info->lock); 392 if (task_tgid(current) == info->notify_owner) 393 remove_notification(info); 394 395 spin_unlock(&info->lock); 396 return 0; 397} 398 399static unsigned int mqueue_poll_file(struct file *filp, struct poll_table_struct *poll_tab) 400{ 401 struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode); 402 int retval = 0; 403 404 poll_wait(filp, &info->wait_q, poll_tab); 405 406 spin_lock(&info->lock); 407 if (info->attr.mq_curmsgs) 408 retval = POLLIN | POLLRDNORM; 409 410 if (info->attr.mq_curmsgs < info->attr.mq_maxmsg) 411 retval |= POLLOUT | POLLWRNORM; 412 spin_unlock(&info->lock); 413 414 return retval; 415} 416 417/* Adds current to info->e_wait_q[sr] before element with smaller prio */ 418static void wq_add(struct mqueue_inode_info *info, int sr, 419 struct ext_wait_queue *ewp) 420{ 421 struct ext_wait_queue *walk; 422 423 ewp->task = current; 424 425 list_for_each_entry(walk, &info->e_wait_q[sr].list, list) { 426 if (walk->task->static_prio <= current->static_prio) { 427 list_add_tail(&ewp->list, &walk->list); 428 return; 429 } 430 } 431 list_add_tail(&ewp->list, &info->e_wait_q[sr].list); 432} 433 434/* 435 * Puts current task to sleep. Caller must hold queue lock. After return 436 * lock isn't held. 437 * sr: SEND or RECV 438 */ 439static int wq_sleep(struct mqueue_inode_info *info, int sr, 440 ktime_t *timeout, struct ext_wait_queue *ewp) 441{ 442 int retval; 443 signed long time; 444 445 wq_add(info, sr, ewp); 446 447 for (;;) { 448 set_current_state(TASK_INTERRUPTIBLE); 449 450 spin_unlock(&info->lock); 451 time = schedule_hrtimeout_range_clock(timeout, 0, 452 HRTIMER_MODE_ABS, CLOCK_REALTIME); 453 454 while (ewp->state == STATE_PENDING) 455 cpu_relax(); 456 457 if (ewp->state == STATE_READY) { 458 retval = 0; 459 goto out; 460 } 461 spin_lock(&info->lock); 462 if (ewp->state == STATE_READY) { 463 retval = 0; 464 goto out_unlock; 465 } 466 if (signal_pending(current)) { 467 retval = -ERESTARTSYS; 468 break; 469 } 470 if (time == 0) { 471 retval = -ETIMEDOUT; 472 break; 473 } 474 } 475 list_del(&ewp->list); 476out_unlock: 477 spin_unlock(&info->lock); 478out: 479 return retval; 480} 481 482/* 483 * Returns waiting task that should be serviced first or NULL if none exists 484 */ 485static struct ext_wait_queue *wq_get_first_waiter( 486 struct mqueue_inode_info *info, int sr) 487{ 488 struct list_head *ptr; 489 490 ptr = info->e_wait_q[sr].list.prev; 491 if (ptr == &info->e_wait_q[sr].list) 492 return NULL; 493 return list_entry(ptr, struct ext_wait_queue, list); 494} 495 496/* Auxiliary functions to manipulate messages' list */ 497static void msg_insert(struct msg_msg *ptr, struct mqueue_inode_info *info) 498{ 499 int k; 500 501 k = info->attr.mq_curmsgs - 1; 502 while (k >= 0 && info->messages[k]->m_type >= ptr->m_type) { 503 info->messages[k + 1] = info->messages[k]; 504 k--; 505 } 506 info->attr.mq_curmsgs++; 507 info->qsize += ptr->m_ts; 508 info->messages[k + 1] = ptr; 509} 510 511static inline struct msg_msg *msg_get(struct mqueue_inode_info *info) 512{ 513 info->qsize -= info->messages[--info->attr.mq_curmsgs]->m_ts; 514 return info->messages[info->attr.mq_curmsgs]; 515} 516 517static inline void set_cookie(struct sk_buff *skb, char code) 518{ 519 ((char*)skb->data)[NOTIFY_COOKIE_LEN-1] = code; 520} 521 522/* 523 * The next function is only to split too long sys_mq_timedsend 524 */ 525static void __do_notify(struct mqueue_inode_info *info) 526{ 527 /* notification 528 * invoked when there is registered process and there isn't process 529 * waiting synchronously for message AND state of queue changed from 530 * empty to not empty. Here we are sure that no one is waiting 531 * synchronously. */ 532 if (info->notify_owner && 533 info->attr.mq_curmsgs == 1) { 534 struct siginfo sig_i; 535 switch (info->notify.sigev_notify) { 536 case SIGEV_NONE: 537 break; 538 case SIGEV_SIGNAL: 539 /* sends signal */ 540 541 sig_i.si_signo = info->notify.sigev_signo; 542 sig_i.si_errno = 0; 543 sig_i.si_code = SI_MESGQ; 544 sig_i.si_value = info->notify.sigev_value; 545 sig_i.si_pid = task_tgid_nr_ns(current, 546 ns_of_pid(info->notify_owner)); 547 sig_i.si_uid = current_uid(); 548 549 kill_pid_info(info->notify.sigev_signo, 550 &sig_i, info->notify_owner); 551 break; 552 case SIGEV_THREAD: 553 set_cookie(info->notify_cookie, NOTIFY_WOKENUP); 554 netlink_sendskb(info->notify_sock, info->notify_cookie); 555 break; 556 } 557 /* after notification unregisters process */ 558 put_pid(info->notify_owner); 559 info->notify_owner = NULL; 560 } 561 wake_up(&info->wait_q); 562} 563 564static int prepare_timeout(const struct timespec __user *u_abs_timeout, 565 ktime_t *expires, struct timespec *ts) 566{ 567 if (copy_from_user(ts, u_abs_timeout, sizeof(struct timespec))) 568 return -EFAULT; 569 if (!timespec_valid(ts)) 570 return -EINVAL; 571 572 *expires = timespec_to_ktime(*ts); 573 return 0; 574} 575 576static void remove_notification(struct mqueue_inode_info *info) 577{ 578 if (info->notify_owner != NULL && 579 info->notify.sigev_notify == SIGEV_THREAD) { 580 set_cookie(info->notify_cookie, NOTIFY_REMOVED); 581 netlink_sendskb(info->notify_sock, info->notify_cookie); 582 } 583 put_pid(info->notify_owner); 584 info->notify_owner = NULL; 585} 586 587static int mq_attr_ok(struct ipc_namespace *ipc_ns, struct mq_attr *attr) 588{ 589 if (attr->mq_maxmsg <= 0 || attr->mq_msgsize <= 0) 590 return 0; 591 if (capable(CAP_SYS_RESOURCE)) { 592 if (attr->mq_maxmsg > HARD_MSGMAX) 593 return 0; 594 } else { 595 if (attr->mq_maxmsg > ipc_ns->mq_msg_max || 596 attr->mq_msgsize > ipc_ns->mq_msgsize_max) 597 return 0; 598 } 599 /* check for overflow */ 600 if (attr->mq_msgsize > ULONG_MAX/attr->mq_maxmsg) 601 return 0; 602 if ((unsigned long)(attr->mq_maxmsg * (attr->mq_msgsize 603 + sizeof (struct msg_msg *))) < 604 (unsigned long)(attr->mq_maxmsg * attr->mq_msgsize)) 605 return 0; 606 return 1; 607} 608 609/* 610 * Invoked when creating a new queue via sys_mq_open 611 */ 612static struct file *do_create(struct ipc_namespace *ipc_ns, struct dentry *dir, 613 struct dentry *dentry, int oflag, umode_t mode, 614 struct mq_attr *attr) 615{ 616 const struct cred *cred = current_cred(); 617 struct file *result; 618 int ret; 619 620 if (attr) { 621 if (!mq_attr_ok(ipc_ns, attr)) { 622 ret = -EINVAL; 623 goto out; 624 } 625 /* store for use during create */ 626 dentry->d_fsdata = attr; 627 } 628 629 mode &= ~current_umask(); 630 ret = mnt_want_write(ipc_ns->mq_mnt); 631 if (ret) 632 goto out; 633 ret = vfs_create(dir->d_inode, dentry, mode, NULL); 634 dentry->d_fsdata = NULL; 635 if (ret) 636 goto out_drop_write; 637 638 result = dentry_open(dentry, ipc_ns->mq_mnt, oflag, cred); 639 /* 640 * dentry_open() took a persistent mnt_want_write(), 641 * so we can now drop this one. 642 */ 643 mnt_drop_write(ipc_ns->mq_mnt); 644 return result; 645 646out_drop_write: 647 mnt_drop_write(ipc_ns->mq_mnt); 648out: 649 dput(dentry); 650 mntput(ipc_ns->mq_mnt); 651 return ERR_PTR(ret); 652} 653 654/* Opens existing queue */ 655static struct file *do_open(struct ipc_namespace *ipc_ns, 656 struct dentry *dentry, int oflag) 657{ 658 int ret; 659 const struct cred *cred = current_cred(); 660 661 static const int oflag2acc[O_ACCMODE] = { MAY_READ, MAY_WRITE, 662 MAY_READ | MAY_WRITE }; 663 664 if ((oflag & O_ACCMODE) == (O_RDWR | O_WRONLY)) { 665 ret = -EINVAL; 666 goto err; 667 } 668 669 if (inode_permission(dentry->d_inode, oflag2acc[oflag & O_ACCMODE])) { 670 ret = -EACCES; 671 goto err; 672 } 673 674 return dentry_open(dentry, ipc_ns->mq_mnt, oflag, cred); 675 676err: 677 dput(dentry); 678 mntput(ipc_ns->mq_mnt); 679 return ERR_PTR(ret); 680} 681 682SYSCALL_DEFINE4(mq_open, const char __user *, u_name, int, oflag, umode_t, mode, 683 struct mq_attr __user *, u_attr) 684{ 685 struct dentry *dentry; 686 struct file *filp; 687 char *name; 688 struct mq_attr attr; 689 int fd, error; 690 struct ipc_namespace *ipc_ns = current->nsproxy->ipc_ns; 691 692 if (u_attr && copy_from_user(&attr, u_attr, sizeof(struct mq_attr))) 693 return -EFAULT; 694 695 audit_mq_open(oflag, mode, u_attr ? &attr : NULL); 696 697 if (IS_ERR(name = getname(u_name))) 698 return PTR_ERR(name); 699 700 fd = get_unused_fd_flags(O_CLOEXEC); 701 if (fd < 0) 702 goto out_putname; 703 704 mutex_lock(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex); 705 dentry = lookup_one_len(name, ipc_ns->mq_mnt->mnt_root, strlen(name)); 706 if (IS_ERR(dentry)) { 707 error = PTR_ERR(dentry); 708 goto out_putfd; 709 } 710 mntget(ipc_ns->mq_mnt); 711 712 if (oflag & O_CREAT) { 713 if (dentry->d_inode) { /* entry already exists */ 714 audit_inode(name, dentry); 715 if (oflag & O_EXCL) { 716 error = -EEXIST; 717 goto out; 718 } 719 filp = do_open(ipc_ns, dentry, oflag); 720 } else { 721 filp = do_create(ipc_ns, ipc_ns->mq_mnt->mnt_root, 722 dentry, oflag, mode, 723 u_attr ? &attr : NULL); 724 } 725 } else { 726 if (!dentry->d_inode) { 727 error = -ENOENT; 728 goto out; 729 } 730 audit_inode(name, dentry); 731 filp = do_open(ipc_ns, dentry, oflag); 732 } 733 734 if (IS_ERR(filp)) { 735 error = PTR_ERR(filp); 736 goto out_putfd; 737 } 738 739 fd_install(fd, filp); 740 goto out_upsem; 741 742out: 743 dput(dentry); 744 mntput(ipc_ns->mq_mnt); 745out_putfd: 746 put_unused_fd(fd); 747 fd = error; 748out_upsem: 749 mutex_unlock(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex); 750out_putname: 751 putname(name); 752 return fd; 753} 754 755SYSCALL_DEFINE1(mq_unlink, const char __user *, u_name) 756{ 757 int err; 758 char *name; 759 struct dentry *dentry; 760 struct inode *inode = NULL; 761 struct ipc_namespace *ipc_ns = current->nsproxy->ipc_ns; 762 763 name = getname(u_name); 764 if (IS_ERR(name)) 765 return PTR_ERR(name); 766 767 mutex_lock_nested(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex, 768 I_MUTEX_PARENT); 769 dentry = lookup_one_len(name, ipc_ns->mq_mnt->mnt_root, strlen(name)); 770 if (IS_ERR(dentry)) { 771 err = PTR_ERR(dentry); 772 goto out_unlock; 773 } 774 775 if (!dentry->d_inode) { 776 err = -ENOENT; 777 goto out_err; 778 } 779 780 inode = dentry->d_inode; 781 if (inode) 782 ihold(inode); 783 err = mnt_want_write(ipc_ns->mq_mnt); 784 if (err) 785 goto out_err; 786 err = vfs_unlink(dentry->d_parent->d_inode, dentry); 787 mnt_drop_write(ipc_ns->mq_mnt); 788out_err: 789 dput(dentry); 790 791out_unlock: 792 mutex_unlock(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex); 793 putname(name); 794 if (inode) 795 iput(inode); 796 797 return err; 798} 799 800/* Pipelined send and receive functions. 801 * 802 * If a receiver finds no waiting message, then it registers itself in the 803 * list of waiting receivers. A sender checks that list before adding the new 804 * message into the message array. If there is a waiting receiver, then it 805 * bypasses the message array and directly hands the message over to the 806 * receiver. 807 * The receiver accepts the message and returns without grabbing the queue 808 * spinlock. Therefore an intermediate STATE_PENDING state and memory barriers 809 * are necessary. The same algorithm is used for sysv semaphores, see 810 * ipc/sem.c for more details. 811 * 812 * The same algorithm is used for senders. 813 */ 814 815/* pipelined_send() - send a message directly to the task waiting in 816 * sys_mq_timedreceive() (without inserting message into a queue). 817 */ 818static inline void pipelined_send(struct mqueue_inode_info *info, 819 struct msg_msg *message, 820 struct ext_wait_queue *receiver) 821{ 822 receiver->msg = message; 823 list_del(&receiver->list); 824 receiver->state = STATE_PENDING; 825 wake_up_process(receiver->task); 826 smp_wmb(); 827 receiver->state = STATE_READY; 828} 829 830/* pipelined_receive() - if there is task waiting in sys_mq_timedsend() 831 * gets its message and put to the queue (we have one free place for sure). */ 832static inline void pipelined_receive(struct mqueue_inode_info *info) 833{ 834 struct ext_wait_queue *sender = wq_get_first_waiter(info, SEND); 835 836 if (!sender) { 837 /* for poll */ 838 wake_up_interruptible(&info->wait_q); 839 return; 840 } 841 msg_insert(sender->msg, info); 842 list_del(&sender->list); 843 sender->state = STATE_PENDING; 844 wake_up_process(sender->task); 845 smp_wmb(); 846 sender->state = STATE_READY; 847} 848 849SYSCALL_DEFINE5(mq_timedsend, mqd_t, mqdes, const char __user *, u_msg_ptr, 850 size_t, msg_len, unsigned int, msg_prio, 851 const struct timespec __user *, u_abs_timeout) 852{ 853 struct file *filp; 854 struct inode *inode; 855 struct ext_wait_queue wait; 856 struct ext_wait_queue *receiver; 857 struct msg_msg *msg_ptr; 858 struct mqueue_inode_info *info; 859 ktime_t expires, *timeout = NULL; 860 struct timespec ts; 861 int ret; 862 863 if (u_abs_timeout) { 864 int res = prepare_timeout(u_abs_timeout, &expires, &ts); 865 if (res) 866 return res; 867 timeout = &expires; 868 } 869 870 if (unlikely(msg_prio >= (unsigned long) MQ_PRIO_MAX)) 871 return -EINVAL; 872 873 audit_mq_sendrecv(mqdes, msg_len, msg_prio, timeout ? &ts : NULL); 874 875 filp = fget(mqdes); 876 if (unlikely(!filp)) { 877 ret = -EBADF; 878 goto out; 879 } 880 881 inode = filp->f_path.dentry->d_inode; 882 if (unlikely(filp->f_op != &mqueue_file_operations)) { 883 ret = -EBADF; 884 goto out_fput; 885 } 886 info = MQUEUE_I(inode); 887 audit_inode(NULL, filp->f_path.dentry); 888 889 if (unlikely(!(filp->f_mode & FMODE_WRITE))) { 890 ret = -EBADF; 891 goto out_fput; 892 } 893 894 if (unlikely(msg_len > info->attr.mq_msgsize)) { 895 ret = -EMSGSIZE; 896 goto out_fput; 897 } 898 899 /* First try to allocate memory, before doing anything with 900 * existing queues. */ 901 msg_ptr = load_msg(u_msg_ptr, msg_len); 902 if (IS_ERR(msg_ptr)) { 903 ret = PTR_ERR(msg_ptr); 904 goto out_fput; 905 } 906 msg_ptr->m_ts = msg_len; 907 msg_ptr->m_type = msg_prio; 908 909 spin_lock(&info->lock); 910 911 if (info->attr.mq_curmsgs == info->attr.mq_maxmsg) { 912 if (filp->f_flags & O_NONBLOCK) { 913 spin_unlock(&info->lock); 914 ret = -EAGAIN; 915 } else { 916 wait.task = current; 917 wait.msg = (void *) msg_ptr; 918 wait.state = STATE_NONE; 919 ret = wq_sleep(info, SEND, timeout, &wait); 920 } 921 if (ret < 0) 922 free_msg(msg_ptr); 923 } else { 924 receiver = wq_get_first_waiter(info, RECV); 925 if (receiver) { 926 pipelined_send(info, msg_ptr, receiver); 927 } else { 928 /* adds message to the queue */ 929 msg_insert(msg_ptr, info); 930 __do_notify(info); 931 } 932 inode->i_atime = inode->i_mtime = inode->i_ctime = 933 CURRENT_TIME; 934 spin_unlock(&info->lock); 935 ret = 0; 936 } 937out_fput: 938 fput(filp); 939out: 940 return ret; 941} 942 943SYSCALL_DEFINE5(mq_timedreceive, mqd_t, mqdes, char __user *, u_msg_ptr, 944 size_t, msg_len, unsigned int __user *, u_msg_prio, 945 const struct timespec __user *, u_abs_timeout) 946{ 947 ssize_t ret; 948 struct msg_msg *msg_ptr; 949 struct file *filp; 950 struct inode *inode; 951 struct mqueue_inode_info *info; 952 struct ext_wait_queue wait; 953 ktime_t expires, *timeout = NULL; 954 struct timespec ts; 955 956 if (u_abs_timeout) { 957 int res = prepare_timeout(u_abs_timeout, &expires, &ts); 958 if (res) 959 return res; 960 timeout = &expires; 961 } 962 963 audit_mq_sendrecv(mqdes, msg_len, 0, timeout ? &ts : NULL); 964 965 filp = fget(mqdes); 966 if (unlikely(!filp)) { 967 ret = -EBADF; 968 goto out; 969 } 970 971 inode = filp->f_path.dentry->d_inode; 972 if (unlikely(filp->f_op != &mqueue_file_operations)) { 973 ret = -EBADF; 974 goto out_fput; 975 } 976 info = MQUEUE_I(inode); 977 audit_inode(NULL, filp->f_path.dentry); 978 979 if (unlikely(!(filp->f_mode & FMODE_READ))) { 980 ret = -EBADF; 981 goto out_fput; 982 } 983 984 /* checks if buffer is big enough */ 985 if (unlikely(msg_len < info->attr.mq_msgsize)) { 986 ret = -EMSGSIZE; 987 goto out_fput; 988 } 989 990 spin_lock(&info->lock); 991 if (info->attr.mq_curmsgs == 0) { 992 if (filp->f_flags & O_NONBLOCK) { 993 spin_unlock(&info->lock); 994 ret = -EAGAIN; 995 } else { 996 wait.task = current; 997 wait.state = STATE_NONE; 998 ret = wq_sleep(info, RECV, timeout, &wait); 999 msg_ptr = wait.msg; 1000 } 1001 } else { 1002 msg_ptr = msg_get(info); 1003 1004 inode->i_atime = inode->i_mtime = inode->i_ctime = 1005 CURRENT_TIME; 1006 1007 /* There is now free space in queue. */ 1008 pipelined_receive(info); 1009 spin_unlock(&info->lock); 1010 ret = 0; 1011 } 1012 if (ret == 0) { 1013 ret = msg_ptr->m_ts; 1014 1015 if ((u_msg_prio && put_user(msg_ptr->m_type, u_msg_prio)) || 1016 store_msg(u_msg_ptr, msg_ptr, msg_ptr->m_ts)) { 1017 ret = -EFAULT; 1018 } 1019 free_msg(msg_ptr); 1020 } 1021out_fput: 1022 fput(filp); 1023out: 1024 return ret; 1025} 1026 1027/* 1028 * Notes: the case when user wants us to deregister (with NULL as pointer) 1029 * and he isn't currently owner of notification, will be silently discarded. 1030 * It isn't explicitly defined in the POSIX. 1031 */ 1032SYSCALL_DEFINE2(mq_notify, mqd_t, mqdes, 1033 const struct sigevent __user *, u_notification) 1034{ 1035 int ret; 1036 struct file *filp; 1037 struct sock *sock; 1038 struct inode *inode; 1039 struct sigevent notification; 1040 struct mqueue_inode_info *info; 1041 struct sk_buff *nc; 1042 1043 if (u_notification) { 1044 if (copy_from_user(¬ification, u_notification, 1045 sizeof(struct sigevent))) 1046 return -EFAULT; 1047 } 1048 1049 audit_mq_notify(mqdes, u_notification ? ¬ification : NULL); 1050 1051 nc = NULL; 1052 sock = NULL; 1053 if (u_notification != NULL) { 1054 if (unlikely(notification.sigev_notify != SIGEV_NONE && 1055 notification.sigev_notify != SIGEV_SIGNAL && 1056 notification.sigev_notify != SIGEV_THREAD)) 1057 return -EINVAL; 1058 if (notification.sigev_notify == SIGEV_SIGNAL && 1059 !valid_signal(notification.sigev_signo)) { 1060 return -EINVAL; 1061 } 1062 if (notification.sigev_notify == SIGEV_THREAD) { 1063 long timeo; 1064 1065 /* create the notify skb */ 1066 nc = alloc_skb(NOTIFY_COOKIE_LEN, GFP_KERNEL); 1067 if (!nc) { 1068 ret = -ENOMEM; 1069 goto out; 1070 } 1071 if (copy_from_user(nc->data, 1072 notification.sigev_value.sival_ptr, 1073 NOTIFY_COOKIE_LEN)) { 1074 ret = -EFAULT; 1075 goto out; 1076 } 1077 1078 /* TODO: add a header? */ 1079 skb_put(nc, NOTIFY_COOKIE_LEN); 1080 /* and attach it to the socket */ 1081retry: 1082 filp = fget(notification.sigev_signo); 1083 if (!filp) { 1084 ret = -EBADF; 1085 goto out; 1086 } 1087 sock = netlink_getsockbyfilp(filp); 1088 fput(filp); 1089 if (IS_ERR(sock)) { 1090 ret = PTR_ERR(sock); 1091 sock = NULL; 1092 goto out; 1093 } 1094 1095 timeo = MAX_SCHEDULE_TIMEOUT; 1096 ret = netlink_attachskb(sock, nc, &timeo, NULL); 1097 if (ret == 1) 1098 goto retry; 1099 if (ret) { 1100 sock = NULL; 1101 nc = NULL; 1102 goto out; 1103 } 1104 } 1105 } 1106 1107 filp = fget(mqdes); 1108 if (!filp) { 1109 ret = -EBADF; 1110 goto out; 1111 } 1112 1113 inode = filp->f_path.dentry->d_inode; 1114 if (unlikely(filp->f_op != &mqueue_file_operations)) { 1115 ret = -EBADF; 1116 goto out_fput; 1117 } 1118 info = MQUEUE_I(inode); 1119 1120 ret = 0; 1121 spin_lock(&info->lock); 1122 if (u_notification == NULL) { 1123 if (info->notify_owner == task_tgid(current)) { 1124 remove_notification(info); 1125 inode->i_atime = inode->i_ctime = CURRENT_TIME; 1126 } 1127 } else if (info->notify_owner != NULL) { 1128 ret = -EBUSY; 1129 } else { 1130 switch (notification.sigev_notify) { 1131 case SIGEV_NONE: 1132 info->notify.sigev_notify = SIGEV_NONE; 1133 break; 1134 case SIGEV_THREAD: 1135 info->notify_sock = sock; 1136 info->notify_cookie = nc; 1137 sock = NULL; 1138 nc = NULL; 1139 info->notify.sigev_notify = SIGEV_THREAD; 1140 break; 1141 case SIGEV_SIGNAL: 1142 info->notify.sigev_signo = notification.sigev_signo; 1143 info->notify.sigev_value = notification.sigev_value; 1144 info->notify.sigev_notify = SIGEV_SIGNAL; 1145 break; 1146 } 1147 1148 info->notify_owner = get_pid(task_tgid(current)); 1149 inode->i_atime = inode->i_ctime = CURRENT_TIME; 1150 } 1151 spin_unlock(&info->lock); 1152out_fput: 1153 fput(filp); 1154out: 1155 if (sock) { 1156 netlink_detachskb(sock, nc); 1157 } else if (nc) { 1158 dev_kfree_skb(nc); 1159 } 1160 return ret; 1161} 1162 1163SYSCALL_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 1216out_fput: 1217 fput(filp); 1218out: 1219 return ret; 1220} 1221 1222static const struct inode_operations mqueue_dir_inode_operations = { 1223 .lookup = simple_lookup, 1224 .create = mqueue_create, 1225 .unlink = mqueue_unlink, 1226}; 1227 1228static 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 1235static 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 1242static struct file_system_type mqueue_fs_type = { 1243 .name = "mqueue", 1244 .mount = mqueue_mount, 1245 .kill_sb = kill_litter_super, 1246}; 1247 1248int 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 1264void mq_clear_sbinfo(struct ipc_namespace *ns) 1265{ 1266 ns->mq_mnt->mnt_sb->s_fs_info = NULL; 1267} 1268 1269void mq_put_mnt(struct ipc_namespace *ns) 1270{ 1271 kern_unmount(ns->mq_mnt); 1272} 1273 1274static 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 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