mqueue.c revision 46690f3718d95e9bb712b6f2b5c869f8494521de
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/ima.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 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_mode = mode; 120 inode->i_uid = current_fsuid(); 121 inode->i_gid = current_fsgid(); 122 inode->i_mtime = inode->i_ctime = inode->i_atime = 123 CURRENT_TIME; 124 125 if (S_ISREG(mode)) { 126 struct mqueue_inode_info *info; 127 struct task_struct *p = current; 128 unsigned long mq_bytes, mq_msg_tblsz; 129 130 inode->i_fop = &mqueue_file_operations; 131 inode->i_size = FILENT_SIZE; 132 /* mqueue specific info */ 133 info = MQUEUE_I(inode); 134 spin_lock_init(&info->lock); 135 init_waitqueue_head(&info->wait_q); 136 INIT_LIST_HEAD(&info->e_wait_q[0].list); 137 INIT_LIST_HEAD(&info->e_wait_q[1].list); 138 info->messages = NULL; 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 mq_bytes = (mq_msg_tblsz + 151 (info->attr.mq_maxmsg * info->attr.mq_msgsize)); 152 153 spin_lock(&mq_lock); 154 if (u->mq_bytes + mq_bytes < u->mq_bytes || 155 u->mq_bytes + mq_bytes > 156 p->signal->rlim[RLIMIT_MSGQUEUE].rlim_cur) { 157 spin_unlock(&mq_lock); 158 goto out_inode; 159 } 160 u->mq_bytes += mq_bytes; 161 spin_unlock(&mq_lock); 162 163 info->messages = kmalloc(mq_msg_tblsz, GFP_KERNEL); 164 if (!info->messages) { 165 spin_lock(&mq_lock); 166 u->mq_bytes -= mq_bytes; 167 spin_unlock(&mq_lock); 168 goto out_inode; 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 make_bad_inode(inode); 183 iput(inode); 184 return NULL; 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 = 0; 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 (!inode) { 201 error = -ENOMEM; 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 } 210 211out: 212 return error; 213} 214 215static int mqueue_get_sb(struct file_system_type *fs_type, 216 int flags, const char *dev_name, 217 void *data, struct vfsmount *mnt) 218{ 219 if (!(flags & MS_KERNMOUNT)) 220 data = current->nsproxy->ipc_ns; 221 return get_sb_ns(fs_type, flags, data, mqueue_fill_super, mnt); 222} 223 224static 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 231static 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 241static void mqueue_destroy_inode(struct inode *inode) 242{ 243 kmem_cache_free(mqueue_inode_cachep, MQUEUE_I(inode)); 244} 245 246static void mqueue_delete_inode(struct inode *inode) 247{ 248 struct mqueue_inode_info *info; 249 struct user_struct *user; 250 unsigned long mq_bytes; 251 int i; 252 struct ipc_namespace *ipc_ns; 253 254 if (S_ISDIR(inode->i_mode)) { 255 clear_inode(inode); 256 return; 257 } 258 ipc_ns = get_ns_from_inode(inode); 259 info = MQUEUE_I(inode); 260 spin_lock(&info->lock); 261 for (i = 0; i < info->attr.mq_curmsgs; i++) 262 free_msg(info->messages[i]); 263 kfree(info->messages); 264 spin_unlock(&info->lock); 265 266 clear_inode(inode); 267 268 mq_bytes = (info->attr.mq_maxmsg * sizeof(struct msg_msg *) + 269 (info->attr.mq_maxmsg * info->attr.mq_msgsize)); 270 user = info->user; 271 if (user) { 272 spin_lock(&mq_lock); 273 user->mq_bytes -= mq_bytes; 274 /* 275 * get_ns_from_inode() ensures that the 276 * (ipc_ns = sb->s_fs_info) is either a valid ipc_ns 277 * to which we now hold a reference, or it is NULL. 278 * We can't put it here under mq_lock, though. 279 */ 280 if (ipc_ns) 281 ipc_ns->mq_queues_count--; 282 spin_unlock(&mq_lock); 283 free_uid(user); 284 } 285 if (ipc_ns) 286 put_ipc_ns(ipc_ns); 287} 288 289static int mqueue_create(struct inode *dir, struct dentry *dentry, 290 int mode, struct nameidata *nd) 291{ 292 struct inode *inode; 293 struct mq_attr *attr = dentry->d_fsdata; 294 int error; 295 struct ipc_namespace *ipc_ns; 296 297 spin_lock(&mq_lock); 298 ipc_ns = __get_ns_from_inode(dir); 299 if (!ipc_ns) { 300 error = -EACCES; 301 goto out_unlock; 302 } 303 if (ipc_ns->mq_queues_count >= ipc_ns->mq_queues_max && 304 !capable(CAP_SYS_RESOURCE)) { 305 error = -ENOSPC; 306 goto out_unlock; 307 } 308 ipc_ns->mq_queues_count++; 309 spin_unlock(&mq_lock); 310 311 inode = mqueue_get_inode(dir->i_sb, ipc_ns, mode, attr); 312 if (!inode) { 313 error = -ENOMEM; 314 spin_lock(&mq_lock); 315 ipc_ns->mq_queues_count--; 316 goto out_unlock; 317 } 318 319 put_ipc_ns(ipc_ns); 320 dir->i_size += DIRENT_SIZE; 321 dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME; 322 323 d_instantiate(dentry, inode); 324 dget(dentry); 325 return 0; 326out_unlock: 327 spin_unlock(&mq_lock); 328 if (ipc_ns) 329 put_ipc_ns(ipc_ns); 330 return error; 331} 332 333static int mqueue_unlink(struct inode *dir, struct dentry *dentry) 334{ 335 struct inode *inode = dentry->d_inode; 336 337 dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME; 338 dir->i_size -= DIRENT_SIZE; 339 drop_nlink(inode); 340 dput(dentry); 341 return 0; 342} 343 344/* 345* This is routine for system read from queue file. 346* To avoid mess with doing here some sort of mq_receive we allow 347* to read only queue size & notification info (the only values 348* that are interesting from user point of view and aren't accessible 349* through std routines) 350*/ 351static ssize_t mqueue_read_file(struct file *filp, char __user *u_data, 352 size_t count, loff_t *off) 353{ 354 struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode); 355 char buffer[FILENT_SIZE]; 356 ssize_t ret; 357 358 spin_lock(&info->lock); 359 snprintf(buffer, sizeof(buffer), 360 "QSIZE:%-10lu NOTIFY:%-5d SIGNO:%-5d NOTIFY_PID:%-6d\n", 361 info->qsize, 362 info->notify_owner ? info->notify.sigev_notify : 0, 363 (info->notify_owner && 364 info->notify.sigev_notify == SIGEV_SIGNAL) ? 365 info->notify.sigev_signo : 0, 366 pid_vnr(info->notify_owner)); 367 spin_unlock(&info->lock); 368 buffer[sizeof(buffer)-1] = '\0'; 369 370 ret = simple_read_from_buffer(u_data, count, off, buffer, 371 strlen(buffer)); 372 if (ret <= 0) 373 return ret; 374 375 filp->f_path.dentry->d_inode->i_atime = filp->f_path.dentry->d_inode->i_ctime = CURRENT_TIME; 376 return ret; 377} 378 379static int mqueue_flush_file(struct file *filp, fl_owner_t id) 380{ 381 struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode); 382 383 spin_lock(&info->lock); 384 if (task_tgid(current) == info->notify_owner) 385 remove_notification(info); 386 387 spin_unlock(&info->lock); 388 return 0; 389} 390 391static unsigned int mqueue_poll_file(struct file *filp, struct poll_table_struct *poll_tab) 392{ 393 struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode); 394 int retval = 0; 395 396 poll_wait(filp, &info->wait_q, poll_tab); 397 398 spin_lock(&info->lock); 399 if (info->attr.mq_curmsgs) 400 retval = POLLIN | POLLRDNORM; 401 402 if (info->attr.mq_curmsgs < info->attr.mq_maxmsg) 403 retval |= POLLOUT | POLLWRNORM; 404 spin_unlock(&info->lock); 405 406 return retval; 407} 408 409/* Adds current to info->e_wait_q[sr] before element with smaller prio */ 410static void wq_add(struct mqueue_inode_info *info, int sr, 411 struct ext_wait_queue *ewp) 412{ 413 struct ext_wait_queue *walk; 414 415 ewp->task = current; 416 417 list_for_each_entry(walk, &info->e_wait_q[sr].list, list) { 418 if (walk->task->static_prio <= current->static_prio) { 419 list_add_tail(&ewp->list, &walk->list); 420 return; 421 } 422 } 423 list_add_tail(&ewp->list, &info->e_wait_q[sr].list); 424} 425 426/* 427 * Puts current task to sleep. Caller must hold queue lock. After return 428 * lock isn't held. 429 * sr: SEND or RECV 430 */ 431static int wq_sleep(struct mqueue_inode_info *info, int sr, 432 long timeout, struct ext_wait_queue *ewp) 433{ 434 int retval; 435 signed long time; 436 437 wq_add(info, sr, ewp); 438 439 for (;;) { 440 set_current_state(TASK_INTERRUPTIBLE); 441 442 spin_unlock(&info->lock); 443 time = schedule_timeout(timeout); 444 445 while (ewp->state == STATE_PENDING) 446 cpu_relax(); 447 448 if (ewp->state == STATE_READY) { 449 retval = 0; 450 goto out; 451 } 452 spin_lock(&info->lock); 453 if (ewp->state == STATE_READY) { 454 retval = 0; 455 goto out_unlock; 456 } 457 if (signal_pending(current)) { 458 retval = -ERESTARTSYS; 459 break; 460 } 461 if (time == 0) { 462 retval = -ETIMEDOUT; 463 break; 464 } 465 } 466 list_del(&ewp->list); 467out_unlock: 468 spin_unlock(&info->lock); 469out: 470 return retval; 471} 472 473/* 474 * Returns waiting task that should be serviced first or NULL if none exists 475 */ 476static struct ext_wait_queue *wq_get_first_waiter( 477 struct mqueue_inode_info *info, int sr) 478{ 479 struct list_head *ptr; 480 481 ptr = info->e_wait_q[sr].list.prev; 482 if (ptr == &info->e_wait_q[sr].list) 483 return NULL; 484 return list_entry(ptr, struct ext_wait_queue, list); 485} 486 487/* Auxiliary functions to manipulate messages' list */ 488static void msg_insert(struct msg_msg *ptr, struct mqueue_inode_info *info) 489{ 490 int k; 491 492 k = info->attr.mq_curmsgs - 1; 493 while (k >= 0 && info->messages[k]->m_type >= ptr->m_type) { 494 info->messages[k + 1] = info->messages[k]; 495 k--; 496 } 497 info->attr.mq_curmsgs++; 498 info->qsize += ptr->m_ts; 499 info->messages[k + 1] = ptr; 500} 501 502static inline struct msg_msg *msg_get(struct mqueue_inode_info *info) 503{ 504 info->qsize -= info->messages[--info->attr.mq_curmsgs]->m_ts; 505 return info->messages[info->attr.mq_curmsgs]; 506} 507 508static inline void set_cookie(struct sk_buff *skb, char code) 509{ 510 ((char*)skb->data)[NOTIFY_COOKIE_LEN-1] = code; 511} 512 513/* 514 * The next function is only to split too long sys_mq_timedsend 515 */ 516static void __do_notify(struct mqueue_inode_info *info) 517{ 518 /* notification 519 * invoked when there is registered process and there isn't process 520 * waiting synchronously for message AND state of queue changed from 521 * empty to not empty. Here we are sure that no one is waiting 522 * synchronously. */ 523 if (info->notify_owner && 524 info->attr.mq_curmsgs == 1) { 525 struct siginfo sig_i; 526 switch (info->notify.sigev_notify) { 527 case SIGEV_NONE: 528 break; 529 case SIGEV_SIGNAL: 530 /* sends signal */ 531 532 sig_i.si_signo = info->notify.sigev_signo; 533 sig_i.si_errno = 0; 534 sig_i.si_code = SI_MESGQ; 535 sig_i.si_value = info->notify.sigev_value; 536 sig_i.si_pid = task_tgid_nr_ns(current, 537 ns_of_pid(info->notify_owner)); 538 sig_i.si_uid = current_uid(); 539 540 kill_pid_info(info->notify.sigev_signo, 541 &sig_i, info->notify_owner); 542 break; 543 case SIGEV_THREAD: 544 set_cookie(info->notify_cookie, NOTIFY_WOKENUP); 545 netlink_sendskb(info->notify_sock, info->notify_cookie); 546 break; 547 } 548 /* after notification unregisters process */ 549 put_pid(info->notify_owner); 550 info->notify_owner = NULL; 551 } 552 wake_up(&info->wait_q); 553} 554 555static long prepare_timeout(struct timespec *p) 556{ 557 struct timespec nowts; 558 long timeout; 559 560 if (p) { 561 if (unlikely(p->tv_nsec < 0 || p->tv_sec < 0 562 || p->tv_nsec >= NSEC_PER_SEC)) 563 return -EINVAL; 564 nowts = CURRENT_TIME; 565 /* first subtract as jiffies can't be too big */ 566 p->tv_sec -= nowts.tv_sec; 567 if (p->tv_nsec < nowts.tv_nsec) { 568 p->tv_nsec += NSEC_PER_SEC; 569 p->tv_sec--; 570 } 571 p->tv_nsec -= nowts.tv_nsec; 572 if (p->tv_sec < 0) 573 return 0; 574 575 timeout = timespec_to_jiffies(p) + 1; 576 } else 577 return MAX_SCHEDULE_TIMEOUT; 578 579 return timeout; 580} 581 582static void remove_notification(struct mqueue_inode_info *info) 583{ 584 if (info->notify_owner != NULL && 585 info->notify.sigev_notify == SIGEV_THREAD) { 586 set_cookie(info->notify_cookie, NOTIFY_REMOVED); 587 netlink_sendskb(info->notify_sock, info->notify_cookie); 588 } 589 put_pid(info->notify_owner); 590 info->notify_owner = NULL; 591} 592 593static int mq_attr_ok(struct ipc_namespace *ipc_ns, struct mq_attr *attr) 594{ 595 if (attr->mq_maxmsg <= 0 || attr->mq_msgsize <= 0) 596 return 0; 597 if (capable(CAP_SYS_RESOURCE)) { 598 if (attr->mq_maxmsg > HARD_MSGMAX) 599 return 0; 600 } else { 601 if (attr->mq_maxmsg > ipc_ns->mq_msg_max || 602 attr->mq_msgsize > ipc_ns->mq_msgsize_max) 603 return 0; 604 } 605 /* check for overflow */ 606 if (attr->mq_msgsize > ULONG_MAX/attr->mq_maxmsg) 607 return 0; 608 if ((unsigned long)(attr->mq_maxmsg * attr->mq_msgsize) + 609 (attr->mq_maxmsg * sizeof (struct msg_msg *)) < 610 (unsigned long)(attr->mq_maxmsg * attr->mq_msgsize)) 611 return 0; 612 return 1; 613} 614 615/* 616 * Invoked when creating a new queue via sys_mq_open 617 */ 618static struct file *do_create(struct ipc_namespace *ipc_ns, struct dentry *dir, 619 struct dentry *dentry, int oflag, mode_t mode, 620 struct mq_attr *attr) 621{ 622 const struct cred *cred = current_cred(); 623 struct file *result; 624 int ret; 625 626 if (attr) { 627 ret = -EINVAL; 628 if (!mq_attr_ok(ipc_ns, attr)) 629 goto out; 630 /* store for use during create */ 631 dentry->d_fsdata = attr; 632 } 633 634 mode &= ~current_umask(); 635 ret = mnt_want_write(ipc_ns->mq_mnt); 636 if (ret) 637 goto out; 638 ret = vfs_create(dir->d_inode, dentry, mode, NULL); 639 dentry->d_fsdata = NULL; 640 if (ret) 641 goto out_drop_write; 642 643 result = dentry_open(dentry, ipc_ns->mq_mnt, oflag, cred); 644 /* 645 * dentry_open() took a persistent mnt_want_write(), 646 * so we can now drop this one. 647 */ 648 mnt_drop_write(ipc_ns->mq_mnt); 649 return result; 650 651out_drop_write: 652 mnt_drop_write(ipc_ns->mq_mnt); 653out: 654 dput(dentry); 655 mntput(ipc_ns->mq_mnt); 656 return ERR_PTR(ret); 657} 658 659/* Opens existing queue */ 660static struct file *do_open(struct ipc_namespace *ipc_ns, 661 struct dentry *dentry, int oflag) 662{ 663 const struct cred *cred = current_cred(); 664 665 static const int oflag2acc[O_ACCMODE] = { MAY_READ, MAY_WRITE, 666 MAY_READ | MAY_WRITE }; 667 668 if ((oflag & O_ACCMODE) == (O_RDWR | O_WRONLY)) { 669 dput(dentry); 670 mntput(ipc_ns->mq_mnt); 671 return ERR_PTR(-EINVAL); 672 } 673 674 if (inode_permission(dentry->d_inode, oflag2acc[oflag & O_ACCMODE])) { 675 dput(dentry); 676 mntput(ipc_ns->mq_mnt); 677 return ERR_PTR(-EACCES); 678 } 679 680 return dentry_open(dentry, ipc_ns->mq_mnt, oflag, cred); 681} 682 683SYSCALL_DEFINE4(mq_open, const char __user *, u_name, int, oflag, mode_t, mode, 684 struct mq_attr __user *, u_attr) 685{ 686 struct dentry *dentry; 687 struct file *filp; 688 char *name; 689 struct mq_attr attr; 690 int fd, error; 691 struct ipc_namespace *ipc_ns = current->nsproxy->ipc_ns; 692 693 if (u_attr && copy_from_user(&attr, u_attr, sizeof(struct mq_attr))) 694 return -EFAULT; 695 696 audit_mq_open(oflag, mode, u_attr ? &attr : NULL); 697 698 if (IS_ERR(name = getname(u_name))) 699 return PTR_ERR(name); 700 701 fd = get_unused_fd_flags(O_CLOEXEC); 702 if (fd < 0) 703 goto out_putname; 704 705 mutex_lock(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex); 706 dentry = lookup_one_len(name, ipc_ns->mq_mnt->mnt_root, strlen(name)); 707 if (IS_ERR(dentry)) { 708 error = PTR_ERR(dentry); 709 goto out_err; 710 } 711 mntget(ipc_ns->mq_mnt); 712 713 if (oflag & O_CREAT) { 714 if (dentry->d_inode) { /* entry already exists */ 715 audit_inode(name, dentry); 716 error = -EEXIST; 717 if (oflag & O_EXCL) 718 goto out; 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 error = -ENOENT; 727 if (!dentry->d_inode) 728 goto out; 729 audit_inode(name, dentry); 730 filp = do_open(ipc_ns, dentry, oflag); 731 } 732 733 if (IS_ERR(filp)) { 734 error = PTR_ERR(filp); 735 goto out_putfd; 736 } 737 ima_counts_get(filp); 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); 747out_err: 748 fd = error; 749out_upsem: 750 mutex_unlock(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex); 751out_putname: 752 putname(name); 753 return fd; 754} 755 756SYSCALL_DEFINE1(mq_unlink, const char __user *, u_name) 757{ 758 int err; 759 char *name; 760 struct dentry *dentry; 761 struct inode *inode = NULL; 762 struct ipc_namespace *ipc_ns = current->nsproxy->ipc_ns; 763 764 name = getname(u_name); 765 if (IS_ERR(name)) 766 return PTR_ERR(name); 767 768 mutex_lock_nested(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex, 769 I_MUTEX_PARENT); 770 dentry = lookup_one_len(name, ipc_ns->mq_mnt->mnt_root, strlen(name)); 771 if (IS_ERR(dentry)) { 772 err = PTR_ERR(dentry); 773 goto out_unlock; 774 } 775 776 if (!dentry->d_inode) { 777 err = -ENOENT; 778 goto out_err; 779 } 780 781 inode = dentry->d_inode; 782 if (inode) 783 atomic_inc(&inode->i_count); 784 err = mnt_want_write(ipc_ns->mq_mnt); 785 if (err) 786 goto out_err; 787 err = vfs_unlink(dentry->d_parent->d_inode, dentry); 788 mnt_drop_write(ipc_ns->mq_mnt); 789out_err: 790 dput(dentry); 791 792out_unlock: 793 mutex_unlock(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex); 794 putname(name); 795 if (inode) 796 iput(inode); 797 798 return err; 799} 800 801/* Pipelined send and receive functions. 802 * 803 * If a receiver finds no waiting message, then it registers itself in the 804 * list of waiting receivers. A sender checks that list before adding the new 805 * message into the message array. If there is a waiting receiver, then it 806 * bypasses the message array and directly hands the message over to the 807 * receiver. 808 * The receiver accepts the message and returns without grabbing the queue 809 * spinlock. Therefore an intermediate STATE_PENDING state and memory barriers 810 * are necessary. The same algorithm is used for sysv semaphores, see 811 * ipc/sem.c for more details. 812 * 813 * The same algorithm is used for senders. 814 */ 815 816/* pipelined_send() - send a message directly to the task waiting in 817 * sys_mq_timedreceive() (without inserting message into a queue). 818 */ 819static inline void pipelined_send(struct mqueue_inode_info *info, 820 struct msg_msg *message, 821 struct ext_wait_queue *receiver) 822{ 823 receiver->msg = message; 824 list_del(&receiver->list); 825 receiver->state = STATE_PENDING; 826 wake_up_process(receiver->task); 827 smp_wmb(); 828 receiver->state = STATE_READY; 829} 830 831/* pipelined_receive() - if there is task waiting in sys_mq_timedsend() 832 * gets its message and put to the queue (we have one free place for sure). */ 833static inline void pipelined_receive(struct mqueue_inode_info *info) 834{ 835 struct ext_wait_queue *sender = wq_get_first_waiter(info, SEND); 836 837 if (!sender) { 838 /* for poll */ 839 wake_up_interruptible(&info->wait_q); 840 return; 841 } 842 msg_insert(sender->msg, info); 843 list_del(&sender->list); 844 sender->state = STATE_PENDING; 845 wake_up_process(sender->task); 846 smp_wmb(); 847 sender->state = STATE_READY; 848} 849 850SYSCALL_DEFINE5(mq_timedsend, mqd_t, mqdes, const char __user *, u_msg_ptr, 851 size_t, msg_len, unsigned int, msg_prio, 852 const struct timespec __user *, u_abs_timeout) 853{ 854 struct file *filp; 855 struct inode *inode; 856 struct ext_wait_queue wait; 857 struct ext_wait_queue *receiver; 858 struct msg_msg *msg_ptr; 859 struct mqueue_inode_info *info; 860 struct timespec ts, *p = NULL; 861 long timeout; 862 int ret; 863 864 if (u_abs_timeout) { 865 if (copy_from_user(&ts, u_abs_timeout, 866 sizeof(struct timespec))) 867 return -EFAULT; 868 p = &ts; 869 } 870 871 if (unlikely(msg_prio >= (unsigned long) MQ_PRIO_MAX)) 872 return -EINVAL; 873 874 audit_mq_sendrecv(mqdes, msg_len, msg_prio, p); 875 timeout = prepare_timeout(p); 876 877 ret = -EBADF; 878 filp = fget(mqdes); 879 if (unlikely(!filp)) 880 goto out; 881 882 inode = filp->f_path.dentry->d_inode; 883 if (unlikely(filp->f_op != &mqueue_file_operations)) 884 goto out_fput; 885 info = MQUEUE_I(inode); 886 audit_inode(NULL, filp->f_path.dentry); 887 888 if (unlikely(!(filp->f_mode & FMODE_WRITE))) 889 goto out_fput; 890 891 if (unlikely(msg_len > info->attr.mq_msgsize)) { 892 ret = -EMSGSIZE; 893 goto out_fput; 894 } 895 896 /* First try to allocate memory, before doing anything with 897 * existing queues. */ 898 msg_ptr = load_msg(u_msg_ptr, msg_len); 899 if (IS_ERR(msg_ptr)) { 900 ret = PTR_ERR(msg_ptr); 901 goto out_fput; 902 } 903 msg_ptr->m_ts = msg_len; 904 msg_ptr->m_type = msg_prio; 905 906 spin_lock(&info->lock); 907 908 if (info->attr.mq_curmsgs == info->attr.mq_maxmsg) { 909 if (filp->f_flags & O_NONBLOCK) { 910 spin_unlock(&info->lock); 911 ret = -EAGAIN; 912 } else if (unlikely(timeout < 0)) { 913 spin_unlock(&info->lock); 914 ret = timeout; 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 long timeout; 948 ssize_t ret; 949 struct msg_msg *msg_ptr; 950 struct file *filp; 951 struct inode *inode; 952 struct mqueue_inode_info *info; 953 struct ext_wait_queue wait; 954 struct timespec ts, *p = NULL; 955 956 if (u_abs_timeout) { 957 if (copy_from_user(&ts, u_abs_timeout, 958 sizeof(struct timespec))) 959 return -EFAULT; 960 p = &ts; 961 } 962 963 audit_mq_sendrecv(mqdes, msg_len, 0, p); 964 timeout = prepare_timeout(p); 965 966 ret = -EBADF; 967 filp = fget(mqdes); 968 if (unlikely(!filp)) 969 goto out; 970 971 inode = filp->f_path.dentry->d_inode; 972 if (unlikely(filp->f_op != &mqueue_file_operations)) 973 goto out_fput; 974 info = MQUEUE_I(inode); 975 audit_inode(NULL, filp->f_path.dentry); 976 977 if (unlikely(!(filp->f_mode & FMODE_READ))) 978 goto out_fput; 979 980 /* checks if buffer is big enough */ 981 if (unlikely(msg_len < info->attr.mq_msgsize)) { 982 ret = -EMSGSIZE; 983 goto out_fput; 984 } 985 986 spin_lock(&info->lock); 987 if (info->attr.mq_curmsgs == 0) { 988 if (filp->f_flags & O_NONBLOCK) { 989 spin_unlock(&info->lock); 990 ret = -EAGAIN; 991 msg_ptr = NULL; 992 } else if (unlikely(timeout < 0)) { 993 spin_unlock(&info->lock); 994 ret = timeout; 995 msg_ptr = NULL; 996 } else { 997 wait.task = current; 998 wait.state = STATE_NONE; 999 ret = wq_sleep(info, RECV, timeout, &wait); 1000 msg_ptr = wait.msg; 1001 } 1002 } else { 1003 msg_ptr = msg_get(info); 1004 1005 inode->i_atime = inode->i_mtime = inode->i_ctime = 1006 CURRENT_TIME; 1007 1008 /* There is now free space in queue. */ 1009 pipelined_receive(info); 1010 spin_unlock(&info->lock); 1011 ret = 0; 1012 } 1013 if (ret == 0) { 1014 ret = msg_ptr->m_ts; 1015 1016 if ((u_msg_prio && put_user(msg_ptr->m_type, u_msg_prio)) || 1017 store_msg(u_msg_ptr, msg_ptr, msg_ptr->m_ts)) { 1018 ret = -EFAULT; 1019 } 1020 free_msg(msg_ptr); 1021 } 1022out_fput: 1023 fput(filp); 1024out: 1025 return ret; 1026} 1027 1028/* 1029 * Notes: the case when user wants us to deregister (with NULL as pointer) 1030 * and he isn't currently owner of notification, will be silently discarded. 1031 * It isn't explicitly defined in the POSIX. 1032 */ 1033SYSCALL_DEFINE2(mq_notify, mqd_t, mqdes, 1034 const struct sigevent __user *, u_notification) 1035{ 1036 int ret; 1037 struct file *filp; 1038 struct sock *sock; 1039 struct inode *inode; 1040 struct sigevent notification; 1041 struct mqueue_inode_info *info; 1042 struct sk_buff *nc; 1043 1044 if (u_notification) { 1045 if (copy_from_user(¬ification, u_notification, 1046 sizeof(struct sigevent))) 1047 return -EFAULT; 1048 } 1049 1050 audit_mq_notify(mqdes, u_notification ? ¬ification : NULL); 1051 1052 nc = NULL; 1053 sock = NULL; 1054 if (u_notification != NULL) { 1055 if (unlikely(notification.sigev_notify != SIGEV_NONE && 1056 notification.sigev_notify != SIGEV_SIGNAL && 1057 notification.sigev_notify != SIGEV_THREAD)) 1058 return -EINVAL; 1059 if (notification.sigev_notify == SIGEV_SIGNAL && 1060 !valid_signal(notification.sigev_signo)) { 1061 return -EINVAL; 1062 } 1063 if (notification.sigev_notify == SIGEV_THREAD) { 1064 long timeo; 1065 1066 /* create the notify skb */ 1067 nc = alloc_skb(NOTIFY_COOKIE_LEN, GFP_KERNEL); 1068 ret = -ENOMEM; 1069 if (!nc) 1070 goto out; 1071 ret = -EFAULT; 1072 if (copy_from_user(nc->data, 1073 notification.sigev_value.sival_ptr, 1074 NOTIFY_COOKIE_LEN)) { 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 ret = -EBADF; 1084 if (!filp) 1085 goto out; 1086 sock = netlink_getsockbyfilp(filp); 1087 fput(filp); 1088 if (IS_ERR(sock)) { 1089 ret = PTR_ERR(sock); 1090 sock = NULL; 1091 goto out; 1092 } 1093 1094 timeo = MAX_SCHEDULE_TIMEOUT; 1095 ret = netlink_attachskb(sock, nc, &timeo, NULL); 1096 if (ret == 1) 1097 goto retry; 1098 if (ret) { 1099 sock = NULL; 1100 nc = NULL; 1101 goto out; 1102 } 1103 } 1104 } 1105 1106 ret = -EBADF; 1107 filp = fget(mqdes); 1108 if (!filp) 1109 goto out; 1110 1111 inode = filp->f_path.dentry->d_inode; 1112 if (unlikely(filp->f_op != &mqueue_file_operations)) 1113 goto out_fput; 1114 info = MQUEUE_I(inode); 1115 1116 ret = 0; 1117 spin_lock(&info->lock); 1118 if (u_notification == NULL) { 1119 if (info->notify_owner == task_tgid(current)) { 1120 remove_notification(info); 1121 inode->i_atime = inode->i_ctime = CURRENT_TIME; 1122 } 1123 } else if (info->notify_owner != NULL) { 1124 ret = -EBUSY; 1125 } else { 1126 switch (notification.sigev_notify) { 1127 case SIGEV_NONE: 1128 info->notify.sigev_notify = SIGEV_NONE; 1129 break; 1130 case SIGEV_THREAD: 1131 info->notify_sock = sock; 1132 info->notify_cookie = nc; 1133 sock = NULL; 1134 nc = NULL; 1135 info->notify.sigev_notify = SIGEV_THREAD; 1136 break; 1137 case SIGEV_SIGNAL: 1138 info->notify.sigev_signo = notification.sigev_signo; 1139 info->notify.sigev_value = notification.sigev_value; 1140 info->notify.sigev_notify = SIGEV_SIGNAL; 1141 break; 1142 } 1143 1144 info->notify_owner = get_pid(task_tgid(current)); 1145 inode->i_atime = inode->i_ctime = CURRENT_TIME; 1146 } 1147 spin_unlock(&info->lock); 1148out_fput: 1149 fput(filp); 1150out: 1151 if (sock) { 1152 netlink_detachskb(sock, nc); 1153 } else if (nc) { 1154 dev_kfree_skb(nc); 1155 } 1156 return ret; 1157} 1158 1159SYSCALL_DEFINE3(mq_getsetattr, mqd_t, mqdes, 1160 const struct mq_attr __user *, u_mqstat, 1161 struct mq_attr __user *, u_omqstat) 1162{ 1163 int ret; 1164 struct mq_attr mqstat, omqstat; 1165 struct file *filp; 1166 struct inode *inode; 1167 struct mqueue_inode_info *info; 1168 1169 if (u_mqstat != NULL) { 1170 if (copy_from_user(&mqstat, u_mqstat, sizeof(struct mq_attr))) 1171 return -EFAULT; 1172 if (mqstat.mq_flags & (~O_NONBLOCK)) 1173 return -EINVAL; 1174 } 1175 1176 ret = -EBADF; 1177 filp = fget(mqdes); 1178 if (!filp) 1179 goto out; 1180 1181 inode = filp->f_path.dentry->d_inode; 1182 if (unlikely(filp->f_op != &mqueue_file_operations)) 1183 goto out_fput; 1184 info = MQUEUE_I(inode); 1185 1186 spin_lock(&info->lock); 1187 1188 omqstat = info->attr; 1189 omqstat.mq_flags = filp->f_flags & O_NONBLOCK; 1190 if (u_mqstat) { 1191 audit_mq_getsetattr(mqdes, &mqstat); 1192 spin_lock(&filp->f_lock); 1193 if (mqstat.mq_flags & O_NONBLOCK) 1194 filp->f_flags |= O_NONBLOCK; 1195 else 1196 filp->f_flags &= ~O_NONBLOCK; 1197 spin_unlock(&filp->f_lock); 1198 1199 inode->i_atime = inode->i_ctime = CURRENT_TIME; 1200 } 1201 1202 spin_unlock(&info->lock); 1203 1204 ret = 0; 1205 if (u_omqstat != NULL && copy_to_user(u_omqstat, &omqstat, 1206 sizeof(struct mq_attr))) 1207 ret = -EFAULT; 1208 1209out_fput: 1210 fput(filp); 1211out: 1212 return ret; 1213} 1214 1215static const struct inode_operations mqueue_dir_inode_operations = { 1216 .lookup = simple_lookup, 1217 .create = mqueue_create, 1218 .unlink = mqueue_unlink, 1219}; 1220 1221static const struct file_operations mqueue_file_operations = { 1222 .flush = mqueue_flush_file, 1223 .poll = mqueue_poll_file, 1224 .read = mqueue_read_file, 1225}; 1226 1227static struct super_operations mqueue_super_ops = { 1228 .alloc_inode = mqueue_alloc_inode, 1229 .destroy_inode = mqueue_destroy_inode, 1230 .statfs = simple_statfs, 1231 .delete_inode = mqueue_delete_inode, 1232 .drop_inode = generic_delete_inode, 1233}; 1234 1235static struct file_system_type mqueue_fs_type = { 1236 .name = "mqueue", 1237 .get_sb = mqueue_get_sb, 1238 .kill_sb = kill_litter_super, 1239}; 1240 1241int mq_init_ns(struct ipc_namespace *ns) 1242{ 1243 ns->mq_queues_count = 0; 1244 ns->mq_queues_max = DFLT_QUEUESMAX; 1245 ns->mq_msg_max = DFLT_MSGMAX; 1246 ns->mq_msgsize_max = DFLT_MSGSIZEMAX; 1247 1248 ns->mq_mnt = kern_mount_data(&mqueue_fs_type, ns); 1249 if (IS_ERR(ns->mq_mnt)) { 1250 int err = PTR_ERR(ns->mq_mnt); 1251 ns->mq_mnt = NULL; 1252 return err; 1253 } 1254 return 0; 1255} 1256 1257void mq_clear_sbinfo(struct ipc_namespace *ns) 1258{ 1259 ns->mq_mnt->mnt_sb->s_fs_info = NULL; 1260} 1261 1262void mq_put_mnt(struct ipc_namespace *ns) 1263{ 1264 mntput(ns->mq_mnt); 1265} 1266 1267static int __init init_mqueue_fs(void) 1268{ 1269 int error; 1270 1271 mqueue_inode_cachep = kmem_cache_create("mqueue_inode_cache", 1272 sizeof(struct mqueue_inode_info), 0, 1273 SLAB_HWCACHE_ALIGN, init_once); 1274 if (mqueue_inode_cachep == NULL) 1275 return -ENOMEM; 1276 1277 /* ignore failues - they are not fatal */ 1278 mq_sysctl_table = mq_register_sysctl_table(); 1279 1280 error = register_filesystem(&mqueue_fs_type); 1281 if (error) 1282 goto out_sysctl; 1283 1284 spin_lock_init(&mq_lock); 1285 1286 init_ipc_ns.mq_mnt = kern_mount_data(&mqueue_fs_type, &init_ipc_ns); 1287 if (IS_ERR(init_ipc_ns.mq_mnt)) { 1288 error = PTR_ERR(init_ipc_ns.mq_mnt); 1289 goto out_filesystem; 1290 } 1291 1292 return 0; 1293 1294out_filesystem: 1295 unregister_filesystem(&mqueue_fs_type); 1296out_sysctl: 1297 if (mq_sysctl_table) 1298 unregister_sysctl_table(mq_sysctl_table); 1299 kmem_cache_destroy(mqueue_inode_cachep); 1300 return error; 1301} 1302 1303__initcall(init_mqueue_fs); 1304