mqueue.c revision c4ea37c26a691ad0b7e86aa5884aab27830e95c9
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 35#include <net/sock.h> 36#include "util.h" 37 38#define MQUEUE_MAGIC 0x19800202 39#define DIRENT_SIZE 20 40#define FILENT_SIZE 80 41 42#define SEND 0 43#define RECV 1 44 45#define STATE_NONE 0 46#define STATE_PENDING 1 47#define STATE_READY 2 48 49/* default values */ 50#define DFLT_QUEUESMAX 256 /* max number of message queues */ 51#define DFLT_MSGMAX 10 /* max number of messages in each queue */ 52#define HARD_MSGMAX (131072/sizeof(void*)) 53#define DFLT_MSGSIZEMAX 8192 /* max message size */ 54 55/* 56 * Define the ranges various user-specified maximum values can 57 * be set to. 58 */ 59#define MIN_MSGMAX 1 /* min value for msg_max */ 60#define MAX_MSGMAX HARD_MSGMAX /* max value for msg_max */ 61#define MIN_MSGSIZEMAX 128 /* min value for msgsize_max */ 62#define MAX_MSGSIZEMAX (8192*128) /* max value for msgsize_max */ 63 64struct ext_wait_queue { /* queue of sleeping tasks */ 65 struct task_struct *task; 66 struct list_head list; 67 struct msg_msg *msg; /* ptr of loaded message */ 68 int state; /* one of STATE_* values */ 69}; 70 71struct mqueue_inode_info { 72 spinlock_t lock; 73 struct inode vfs_inode; 74 wait_queue_head_t wait_q; 75 76 struct msg_msg **messages; 77 struct mq_attr attr; 78 79 struct sigevent notify; 80 struct pid* notify_owner; 81 struct user_struct *user; /* user who created, for accounting */ 82 struct sock *notify_sock; 83 struct sk_buff *notify_cookie; 84 85 /* for tasks waiting for free space and messages, respectively */ 86 struct ext_wait_queue e_wait_q[2]; 87 88 unsigned long qsize; /* size of queue in memory (sum of all msgs) */ 89}; 90 91static const struct inode_operations mqueue_dir_inode_operations; 92static const struct file_operations mqueue_file_operations; 93static struct super_operations mqueue_super_ops; 94static void remove_notification(struct mqueue_inode_info *info); 95 96static spinlock_t mq_lock; 97static struct kmem_cache *mqueue_inode_cachep; 98static struct vfsmount *mqueue_mnt; 99 100static unsigned int queues_count; 101static unsigned int queues_max = DFLT_QUEUESMAX; 102static unsigned int msg_max = DFLT_MSGMAX; 103static unsigned int msgsize_max = DFLT_MSGSIZEMAX; 104 105static struct ctl_table_header * mq_sysctl_table; 106 107static inline struct mqueue_inode_info *MQUEUE_I(struct inode *inode) 108{ 109 return container_of(inode, struct mqueue_inode_info, vfs_inode); 110} 111 112static struct inode *mqueue_get_inode(struct super_block *sb, int mode, 113 struct mq_attr *attr) 114{ 115 struct user_struct *u = current_user(); 116 struct inode *inode; 117 118 inode = new_inode(sb); 119 if (inode) { 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->messages = NULL; 140 info->notify_owner = NULL; 141 info->qsize = 0; 142 info->user = NULL; /* set when all is ok */ 143 memset(&info->attr, 0, sizeof(info->attr)); 144 info->attr.mq_maxmsg = msg_max; 145 info->attr.mq_msgsize = msgsize_max; 146 if (attr) { 147 info->attr.mq_maxmsg = attr->mq_maxmsg; 148 info->attr.mq_msgsize = attr->mq_msgsize; 149 } 150 mq_msg_tblsz = info->attr.mq_maxmsg * sizeof(struct msg_msg *); 151 mq_bytes = (mq_msg_tblsz + 152 (info->attr.mq_maxmsg * info->attr.mq_msgsize)); 153 154 spin_lock(&mq_lock); 155 if (u->mq_bytes + mq_bytes < u->mq_bytes || 156 u->mq_bytes + mq_bytes > 157 p->signal->rlim[RLIMIT_MSGQUEUE].rlim_cur) { 158 spin_unlock(&mq_lock); 159 goto out_inode; 160 } 161 u->mq_bytes += mq_bytes; 162 spin_unlock(&mq_lock); 163 164 info->messages = kmalloc(mq_msg_tblsz, GFP_KERNEL); 165 if (!info->messages) { 166 spin_lock(&mq_lock); 167 u->mq_bytes -= mq_bytes; 168 spin_unlock(&mq_lock); 169 goto out_inode; 170 } 171 /* all is ok */ 172 info->user = get_uid(u); 173 } else if (S_ISDIR(mode)) { 174 inc_nlink(inode); 175 /* Some things misbehave if size == 0 on a directory */ 176 inode->i_size = 2 * DIRENT_SIZE; 177 inode->i_op = &mqueue_dir_inode_operations; 178 inode->i_fop = &simple_dir_operations; 179 } 180 } 181 return inode; 182out_inode: 183 make_bad_inode(inode); 184 iput(inode); 185 return NULL; 186} 187 188static int mqueue_fill_super(struct super_block *sb, void *data, int silent) 189{ 190 struct inode *inode; 191 192 sb->s_blocksize = PAGE_CACHE_SIZE; 193 sb->s_blocksize_bits = PAGE_CACHE_SHIFT; 194 sb->s_magic = MQUEUE_MAGIC; 195 sb->s_op = &mqueue_super_ops; 196 197 inode = mqueue_get_inode(sb, S_IFDIR | S_ISVTX | S_IRWXUGO, NULL); 198 if (!inode) 199 return -ENOMEM; 200 201 sb->s_root = d_alloc_root(inode); 202 if (!sb->s_root) { 203 iput(inode); 204 return -ENOMEM; 205 } 206 207 return 0; 208} 209 210static int mqueue_get_sb(struct file_system_type *fs_type, 211 int flags, const char *dev_name, 212 void *data, struct vfsmount *mnt) 213{ 214 return get_sb_single(fs_type, flags, data, mqueue_fill_super, mnt); 215} 216 217static void init_once(void *foo) 218{ 219 struct mqueue_inode_info *p = (struct mqueue_inode_info *) foo; 220 221 inode_init_once(&p->vfs_inode); 222} 223 224static struct inode *mqueue_alloc_inode(struct super_block *sb) 225{ 226 struct mqueue_inode_info *ei; 227 228 ei = kmem_cache_alloc(mqueue_inode_cachep, GFP_KERNEL); 229 if (!ei) 230 return NULL; 231 return &ei->vfs_inode; 232} 233 234static void mqueue_destroy_inode(struct inode *inode) 235{ 236 kmem_cache_free(mqueue_inode_cachep, MQUEUE_I(inode)); 237} 238 239static void mqueue_delete_inode(struct inode *inode) 240{ 241 struct mqueue_inode_info *info; 242 struct user_struct *user; 243 unsigned long mq_bytes; 244 int i; 245 246 if (S_ISDIR(inode->i_mode)) { 247 clear_inode(inode); 248 return; 249 } 250 info = MQUEUE_I(inode); 251 spin_lock(&info->lock); 252 for (i = 0; i < info->attr.mq_curmsgs; i++) 253 free_msg(info->messages[i]); 254 kfree(info->messages); 255 spin_unlock(&info->lock); 256 257 clear_inode(inode); 258 259 mq_bytes = (info->attr.mq_maxmsg * sizeof(struct msg_msg *) + 260 (info->attr.mq_maxmsg * info->attr.mq_msgsize)); 261 user = info->user; 262 if (user) { 263 spin_lock(&mq_lock); 264 user->mq_bytes -= mq_bytes; 265 queues_count--; 266 spin_unlock(&mq_lock); 267 free_uid(user); 268 } 269} 270 271static int mqueue_create(struct inode *dir, struct dentry *dentry, 272 int mode, struct nameidata *nd) 273{ 274 struct inode *inode; 275 struct mq_attr *attr = dentry->d_fsdata; 276 int error; 277 278 spin_lock(&mq_lock); 279 if (queues_count >= queues_max && !capable(CAP_SYS_RESOURCE)) { 280 error = -ENOSPC; 281 goto out_lock; 282 } 283 queues_count++; 284 spin_unlock(&mq_lock); 285 286 inode = mqueue_get_inode(dir->i_sb, mode, attr); 287 if (!inode) { 288 error = -ENOMEM; 289 spin_lock(&mq_lock); 290 queues_count--; 291 goto out_lock; 292 } 293 294 dir->i_size += DIRENT_SIZE; 295 dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME; 296 297 d_instantiate(dentry, inode); 298 dget(dentry); 299 return 0; 300out_lock: 301 spin_unlock(&mq_lock); 302 return error; 303} 304 305static int mqueue_unlink(struct inode *dir, struct dentry *dentry) 306{ 307 struct inode *inode = dentry->d_inode; 308 309 dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME; 310 dir->i_size -= DIRENT_SIZE; 311 drop_nlink(inode); 312 dput(dentry); 313 return 0; 314} 315 316/* 317* This is routine for system read from queue file. 318* To avoid mess with doing here some sort of mq_receive we allow 319* to read only queue size & notification info (the only values 320* that are interesting from user point of view and aren't accessible 321* through std routines) 322*/ 323static ssize_t mqueue_read_file(struct file *filp, char __user *u_data, 324 size_t count, loff_t *off) 325{ 326 struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode); 327 char buffer[FILENT_SIZE]; 328 ssize_t ret; 329 330 spin_lock(&info->lock); 331 snprintf(buffer, sizeof(buffer), 332 "QSIZE:%-10lu NOTIFY:%-5d SIGNO:%-5d NOTIFY_PID:%-6d\n", 333 info->qsize, 334 info->notify_owner ? info->notify.sigev_notify : 0, 335 (info->notify_owner && 336 info->notify.sigev_notify == SIGEV_SIGNAL) ? 337 info->notify.sigev_signo : 0, 338 pid_vnr(info->notify_owner)); 339 spin_unlock(&info->lock); 340 buffer[sizeof(buffer)-1] = '\0'; 341 342 ret = simple_read_from_buffer(u_data, count, off, buffer, 343 strlen(buffer)); 344 if (ret <= 0) 345 return ret; 346 347 filp->f_path.dentry->d_inode->i_atime = filp->f_path.dentry->d_inode->i_ctime = CURRENT_TIME; 348 return ret; 349} 350 351static int mqueue_flush_file(struct file *filp, fl_owner_t id) 352{ 353 struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode); 354 355 spin_lock(&info->lock); 356 if (task_tgid(current) == info->notify_owner) 357 remove_notification(info); 358 359 spin_unlock(&info->lock); 360 return 0; 361} 362 363static unsigned int mqueue_poll_file(struct file *filp, struct poll_table_struct *poll_tab) 364{ 365 struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode); 366 int retval = 0; 367 368 poll_wait(filp, &info->wait_q, poll_tab); 369 370 spin_lock(&info->lock); 371 if (info->attr.mq_curmsgs) 372 retval = POLLIN | POLLRDNORM; 373 374 if (info->attr.mq_curmsgs < info->attr.mq_maxmsg) 375 retval |= POLLOUT | POLLWRNORM; 376 spin_unlock(&info->lock); 377 378 return retval; 379} 380 381/* Adds current to info->e_wait_q[sr] before element with smaller prio */ 382static void wq_add(struct mqueue_inode_info *info, int sr, 383 struct ext_wait_queue *ewp) 384{ 385 struct ext_wait_queue *walk; 386 387 ewp->task = current; 388 389 list_for_each_entry(walk, &info->e_wait_q[sr].list, list) { 390 if (walk->task->static_prio <= current->static_prio) { 391 list_add_tail(&ewp->list, &walk->list); 392 return; 393 } 394 } 395 list_add_tail(&ewp->list, &info->e_wait_q[sr].list); 396} 397 398/* 399 * Puts current task to sleep. Caller must hold queue lock. After return 400 * lock isn't held. 401 * sr: SEND or RECV 402 */ 403static int wq_sleep(struct mqueue_inode_info *info, int sr, 404 long timeout, struct ext_wait_queue *ewp) 405{ 406 int retval; 407 signed long time; 408 409 wq_add(info, sr, ewp); 410 411 for (;;) { 412 set_current_state(TASK_INTERRUPTIBLE); 413 414 spin_unlock(&info->lock); 415 time = schedule_timeout(timeout); 416 417 while (ewp->state == STATE_PENDING) 418 cpu_relax(); 419 420 if (ewp->state == STATE_READY) { 421 retval = 0; 422 goto out; 423 } 424 spin_lock(&info->lock); 425 if (ewp->state == STATE_READY) { 426 retval = 0; 427 goto out_unlock; 428 } 429 if (signal_pending(current)) { 430 retval = -ERESTARTSYS; 431 break; 432 } 433 if (time == 0) { 434 retval = -ETIMEDOUT; 435 break; 436 } 437 } 438 list_del(&ewp->list); 439out_unlock: 440 spin_unlock(&info->lock); 441out: 442 return retval; 443} 444 445/* 446 * Returns waiting task that should be serviced first or NULL if none exists 447 */ 448static struct ext_wait_queue *wq_get_first_waiter( 449 struct mqueue_inode_info *info, int sr) 450{ 451 struct list_head *ptr; 452 453 ptr = info->e_wait_q[sr].list.prev; 454 if (ptr == &info->e_wait_q[sr].list) 455 return NULL; 456 return list_entry(ptr, struct ext_wait_queue, list); 457} 458 459/* Auxiliary functions to manipulate messages' list */ 460static void msg_insert(struct msg_msg *ptr, struct mqueue_inode_info *info) 461{ 462 int k; 463 464 k = info->attr.mq_curmsgs - 1; 465 while (k >= 0 && info->messages[k]->m_type >= ptr->m_type) { 466 info->messages[k + 1] = info->messages[k]; 467 k--; 468 } 469 info->attr.mq_curmsgs++; 470 info->qsize += ptr->m_ts; 471 info->messages[k + 1] = ptr; 472} 473 474static inline struct msg_msg *msg_get(struct mqueue_inode_info *info) 475{ 476 info->qsize -= info->messages[--info->attr.mq_curmsgs]->m_ts; 477 return info->messages[info->attr.mq_curmsgs]; 478} 479 480static inline void set_cookie(struct sk_buff *skb, char code) 481{ 482 ((char*)skb->data)[NOTIFY_COOKIE_LEN-1] = code; 483} 484 485/* 486 * The next function is only to split too long sys_mq_timedsend 487 */ 488static void __do_notify(struct mqueue_inode_info *info) 489{ 490 /* notification 491 * invoked when there is registered process and there isn't process 492 * waiting synchronously for message AND state of queue changed from 493 * empty to not empty. Here we are sure that no one is waiting 494 * synchronously. */ 495 if (info->notify_owner && 496 info->attr.mq_curmsgs == 1) { 497 struct siginfo sig_i; 498 switch (info->notify.sigev_notify) { 499 case SIGEV_NONE: 500 break; 501 case SIGEV_SIGNAL: 502 /* sends signal */ 503 504 sig_i.si_signo = info->notify.sigev_signo; 505 sig_i.si_errno = 0; 506 sig_i.si_code = SI_MESGQ; 507 sig_i.si_value = info->notify.sigev_value; 508 sig_i.si_pid = task_tgid_nr_ns(current, 509 ns_of_pid(info->notify_owner)); 510 sig_i.si_uid = current_uid(); 511 512 kill_pid_info(info->notify.sigev_signo, 513 &sig_i, info->notify_owner); 514 break; 515 case SIGEV_THREAD: 516 set_cookie(info->notify_cookie, NOTIFY_WOKENUP); 517 netlink_sendskb(info->notify_sock, info->notify_cookie); 518 break; 519 } 520 /* after notification unregisters process */ 521 put_pid(info->notify_owner); 522 info->notify_owner = NULL; 523 } 524 wake_up(&info->wait_q); 525} 526 527static long prepare_timeout(struct timespec *p) 528{ 529 struct timespec nowts; 530 long timeout; 531 532 if (p) { 533 if (unlikely(p->tv_nsec < 0 || p->tv_sec < 0 534 || p->tv_nsec >= NSEC_PER_SEC)) 535 return -EINVAL; 536 nowts = CURRENT_TIME; 537 /* first subtract as jiffies can't be too big */ 538 p->tv_sec -= nowts.tv_sec; 539 if (p->tv_nsec < nowts.tv_nsec) { 540 p->tv_nsec += NSEC_PER_SEC; 541 p->tv_sec--; 542 } 543 p->tv_nsec -= nowts.tv_nsec; 544 if (p->tv_sec < 0) 545 return 0; 546 547 timeout = timespec_to_jiffies(p) + 1; 548 } else 549 return MAX_SCHEDULE_TIMEOUT; 550 551 return timeout; 552} 553 554static void remove_notification(struct mqueue_inode_info *info) 555{ 556 if (info->notify_owner != NULL && 557 info->notify.sigev_notify == SIGEV_THREAD) { 558 set_cookie(info->notify_cookie, NOTIFY_REMOVED); 559 netlink_sendskb(info->notify_sock, info->notify_cookie); 560 } 561 put_pid(info->notify_owner); 562 info->notify_owner = NULL; 563} 564 565static int mq_attr_ok(struct mq_attr *attr) 566{ 567 if (attr->mq_maxmsg <= 0 || attr->mq_msgsize <= 0) 568 return 0; 569 if (capable(CAP_SYS_RESOURCE)) { 570 if (attr->mq_maxmsg > HARD_MSGMAX) 571 return 0; 572 } else { 573 if (attr->mq_maxmsg > msg_max || 574 attr->mq_msgsize > msgsize_max) 575 return 0; 576 } 577 /* check for overflow */ 578 if (attr->mq_msgsize > ULONG_MAX/attr->mq_maxmsg) 579 return 0; 580 if ((unsigned long)(attr->mq_maxmsg * attr->mq_msgsize) + 581 (attr->mq_maxmsg * sizeof (struct msg_msg *)) < 582 (unsigned long)(attr->mq_maxmsg * attr->mq_msgsize)) 583 return 0; 584 return 1; 585} 586 587/* 588 * Invoked when creating a new queue via sys_mq_open 589 */ 590static struct file *do_create(struct dentry *dir, struct dentry *dentry, 591 int oflag, mode_t mode, struct mq_attr *attr) 592{ 593 const struct cred *cred = current_cred(); 594 struct file *result; 595 int ret; 596 597 if (attr) { 598 ret = -EINVAL; 599 if (!mq_attr_ok(attr)) 600 goto out; 601 /* store for use during create */ 602 dentry->d_fsdata = attr; 603 } 604 605 mode &= ~current->fs->umask; 606 ret = mnt_want_write(mqueue_mnt); 607 if (ret) 608 goto out; 609 ret = vfs_create(dir->d_inode, dentry, mode, NULL); 610 dentry->d_fsdata = NULL; 611 if (ret) 612 goto out_drop_write; 613 614 result = dentry_open(dentry, mqueue_mnt, oflag, cred); 615 /* 616 * dentry_open() took a persistent mnt_want_write(), 617 * so we can now drop this one. 618 */ 619 mnt_drop_write(mqueue_mnt); 620 return result; 621 622out_drop_write: 623 mnt_drop_write(mqueue_mnt); 624out: 625 dput(dentry); 626 mntput(mqueue_mnt); 627 return ERR_PTR(ret); 628} 629 630/* Opens existing queue */ 631static struct file *do_open(struct dentry *dentry, int oflag) 632{ 633 const struct cred *cred = current_cred(); 634 635 static const int oflag2acc[O_ACCMODE] = { MAY_READ, MAY_WRITE, 636 MAY_READ | MAY_WRITE }; 637 638 if ((oflag & O_ACCMODE) == (O_RDWR | O_WRONLY)) { 639 dput(dentry); 640 mntput(mqueue_mnt); 641 return ERR_PTR(-EINVAL); 642 } 643 644 if (inode_permission(dentry->d_inode, oflag2acc[oflag & O_ACCMODE])) { 645 dput(dentry); 646 mntput(mqueue_mnt); 647 return ERR_PTR(-EACCES); 648 } 649 650 return dentry_open(dentry, mqueue_mnt, oflag, cred); 651} 652 653SYSCALL_DEFINE4(mq_open, const char __user *, u_name, int, oflag, mode_t, mode, 654 struct mq_attr __user *, u_attr) 655{ 656 struct dentry *dentry; 657 struct file *filp; 658 char *name; 659 struct mq_attr attr; 660 int fd, error; 661 662 if (u_attr && copy_from_user(&attr, u_attr, sizeof(struct mq_attr))) 663 return -EFAULT; 664 665 audit_mq_open(oflag, mode, u_attr ? &attr : NULL); 666 667 if (IS_ERR(name = getname(u_name))) 668 return PTR_ERR(name); 669 670 fd = get_unused_fd_flags(O_CLOEXEC); 671 if (fd < 0) 672 goto out_putname; 673 674 mutex_lock(&mqueue_mnt->mnt_root->d_inode->i_mutex); 675 dentry = lookup_one_len(name, mqueue_mnt->mnt_root, strlen(name)); 676 if (IS_ERR(dentry)) { 677 error = PTR_ERR(dentry); 678 goto out_err; 679 } 680 mntget(mqueue_mnt); 681 682 if (oflag & O_CREAT) { 683 if (dentry->d_inode) { /* entry already exists */ 684 audit_inode(name, dentry); 685 error = -EEXIST; 686 if (oflag & O_EXCL) 687 goto out; 688 filp = do_open(dentry, oflag); 689 } else { 690 filp = do_create(mqueue_mnt->mnt_root, dentry, 691 oflag, mode, 692 u_attr ? &attr : NULL); 693 } 694 } else { 695 error = -ENOENT; 696 if (!dentry->d_inode) 697 goto out; 698 audit_inode(name, dentry); 699 filp = do_open(dentry, oflag); 700 } 701 702 if (IS_ERR(filp)) { 703 error = PTR_ERR(filp); 704 goto out_putfd; 705 } 706 707 fd_install(fd, filp); 708 goto out_upsem; 709 710out: 711 dput(dentry); 712 mntput(mqueue_mnt); 713out_putfd: 714 put_unused_fd(fd); 715out_err: 716 fd = error; 717out_upsem: 718 mutex_unlock(&mqueue_mnt->mnt_root->d_inode->i_mutex); 719out_putname: 720 putname(name); 721 return fd; 722} 723 724SYSCALL_DEFINE1(mq_unlink, const char __user *, u_name) 725{ 726 int err; 727 char *name; 728 struct dentry *dentry; 729 struct inode *inode = NULL; 730 731 name = getname(u_name); 732 if (IS_ERR(name)) 733 return PTR_ERR(name); 734 735 mutex_lock_nested(&mqueue_mnt->mnt_root->d_inode->i_mutex, 736 I_MUTEX_PARENT); 737 dentry = lookup_one_len(name, mqueue_mnt->mnt_root, strlen(name)); 738 if (IS_ERR(dentry)) { 739 err = PTR_ERR(dentry); 740 goto out_unlock; 741 } 742 743 if (!dentry->d_inode) { 744 err = -ENOENT; 745 goto out_err; 746 } 747 748 inode = dentry->d_inode; 749 if (inode) 750 atomic_inc(&inode->i_count); 751 err = mnt_want_write(mqueue_mnt); 752 if (err) 753 goto out_err; 754 err = vfs_unlink(dentry->d_parent->d_inode, dentry); 755 mnt_drop_write(mqueue_mnt); 756out_err: 757 dput(dentry); 758 759out_unlock: 760 mutex_unlock(&mqueue_mnt->mnt_root->d_inode->i_mutex); 761 putname(name); 762 if (inode) 763 iput(inode); 764 765 return err; 766} 767 768/* Pipelined send and receive functions. 769 * 770 * If a receiver finds no waiting message, then it registers itself in the 771 * list of waiting receivers. A sender checks that list before adding the new 772 * message into the message array. If there is a waiting receiver, then it 773 * bypasses the message array and directly hands the message over to the 774 * receiver. 775 * The receiver accepts the message and returns without grabbing the queue 776 * spinlock. Therefore an intermediate STATE_PENDING state and memory barriers 777 * are necessary. The same algorithm is used for sysv semaphores, see 778 * ipc/sem.c for more details. 779 * 780 * The same algorithm is used for senders. 781 */ 782 783/* pipelined_send() - send a message directly to the task waiting in 784 * sys_mq_timedreceive() (without inserting message into a queue). 785 */ 786static inline void pipelined_send(struct mqueue_inode_info *info, 787 struct msg_msg *message, 788 struct ext_wait_queue *receiver) 789{ 790 receiver->msg = message; 791 list_del(&receiver->list); 792 receiver->state = STATE_PENDING; 793 wake_up_process(receiver->task); 794 smp_wmb(); 795 receiver->state = STATE_READY; 796} 797 798/* pipelined_receive() - if there is task waiting in sys_mq_timedsend() 799 * gets its message and put to the queue (we have one free place for sure). */ 800static inline void pipelined_receive(struct mqueue_inode_info *info) 801{ 802 struct ext_wait_queue *sender = wq_get_first_waiter(info, SEND); 803 804 if (!sender) { 805 /* for poll */ 806 wake_up_interruptible(&info->wait_q); 807 return; 808 } 809 msg_insert(sender->msg, info); 810 list_del(&sender->list); 811 sender->state = STATE_PENDING; 812 wake_up_process(sender->task); 813 smp_wmb(); 814 sender->state = STATE_READY; 815} 816 817SYSCALL_DEFINE5(mq_timedsend, mqd_t, mqdes, const char __user *, u_msg_ptr, 818 size_t, msg_len, unsigned int, msg_prio, 819 const struct timespec __user *, u_abs_timeout) 820{ 821 struct file *filp; 822 struct inode *inode; 823 struct ext_wait_queue wait; 824 struct ext_wait_queue *receiver; 825 struct msg_msg *msg_ptr; 826 struct mqueue_inode_info *info; 827 struct timespec ts, *p = NULL; 828 long timeout; 829 int ret; 830 831 if (u_abs_timeout) { 832 if (copy_from_user(&ts, u_abs_timeout, 833 sizeof(struct timespec))) 834 return -EFAULT; 835 p = &ts; 836 } 837 838 if (unlikely(msg_prio >= (unsigned long) MQ_PRIO_MAX)) 839 return -EINVAL; 840 841 audit_mq_sendrecv(mqdes, msg_len, msg_prio, p); 842 timeout = prepare_timeout(p); 843 844 ret = -EBADF; 845 filp = fget(mqdes); 846 if (unlikely(!filp)) 847 goto out; 848 849 inode = filp->f_path.dentry->d_inode; 850 if (unlikely(filp->f_op != &mqueue_file_operations)) 851 goto out_fput; 852 info = MQUEUE_I(inode); 853 audit_inode(NULL, filp->f_path.dentry); 854 855 if (unlikely(!(filp->f_mode & FMODE_WRITE))) 856 goto out_fput; 857 858 if (unlikely(msg_len > info->attr.mq_msgsize)) { 859 ret = -EMSGSIZE; 860 goto out_fput; 861 } 862 863 /* First try to allocate memory, before doing anything with 864 * existing queues. */ 865 msg_ptr = load_msg(u_msg_ptr, msg_len); 866 if (IS_ERR(msg_ptr)) { 867 ret = PTR_ERR(msg_ptr); 868 goto out_fput; 869 } 870 msg_ptr->m_ts = msg_len; 871 msg_ptr->m_type = msg_prio; 872 873 spin_lock(&info->lock); 874 875 if (info->attr.mq_curmsgs == info->attr.mq_maxmsg) { 876 if (filp->f_flags & O_NONBLOCK) { 877 spin_unlock(&info->lock); 878 ret = -EAGAIN; 879 } else if (unlikely(timeout < 0)) { 880 spin_unlock(&info->lock); 881 ret = timeout; 882 } else { 883 wait.task = current; 884 wait.msg = (void *) msg_ptr; 885 wait.state = STATE_NONE; 886 ret = wq_sleep(info, SEND, timeout, &wait); 887 } 888 if (ret < 0) 889 free_msg(msg_ptr); 890 } else { 891 receiver = wq_get_first_waiter(info, RECV); 892 if (receiver) { 893 pipelined_send(info, msg_ptr, receiver); 894 } else { 895 /* adds message to the queue */ 896 msg_insert(msg_ptr, info); 897 __do_notify(info); 898 } 899 inode->i_atime = inode->i_mtime = inode->i_ctime = 900 CURRENT_TIME; 901 spin_unlock(&info->lock); 902 ret = 0; 903 } 904out_fput: 905 fput(filp); 906out: 907 return ret; 908} 909 910SYSCALL_DEFINE5(mq_timedreceive, mqd_t, mqdes, char __user *, u_msg_ptr, 911 size_t, msg_len, unsigned int __user *, u_msg_prio, 912 const struct timespec __user *, u_abs_timeout) 913{ 914 long timeout; 915 ssize_t ret; 916 struct msg_msg *msg_ptr; 917 struct file *filp; 918 struct inode *inode; 919 struct mqueue_inode_info *info; 920 struct ext_wait_queue wait; 921 struct timespec ts, *p = NULL; 922 923 if (u_abs_timeout) { 924 if (copy_from_user(&ts, u_abs_timeout, 925 sizeof(struct timespec))) 926 return -EFAULT; 927 p = &ts; 928 } 929 930 audit_mq_sendrecv(mqdes, msg_len, 0, p); 931 timeout = prepare_timeout(p); 932 933 ret = -EBADF; 934 filp = fget(mqdes); 935 if (unlikely(!filp)) 936 goto out; 937 938 inode = filp->f_path.dentry->d_inode; 939 if (unlikely(filp->f_op != &mqueue_file_operations)) 940 goto out_fput; 941 info = MQUEUE_I(inode); 942 audit_inode(NULL, filp->f_path.dentry); 943 944 if (unlikely(!(filp->f_mode & FMODE_READ))) 945 goto out_fput; 946 947 /* checks if buffer is big enough */ 948 if (unlikely(msg_len < info->attr.mq_msgsize)) { 949 ret = -EMSGSIZE; 950 goto out_fput; 951 } 952 953 spin_lock(&info->lock); 954 if (info->attr.mq_curmsgs == 0) { 955 if (filp->f_flags & O_NONBLOCK) { 956 spin_unlock(&info->lock); 957 ret = -EAGAIN; 958 msg_ptr = NULL; 959 } else if (unlikely(timeout < 0)) { 960 spin_unlock(&info->lock); 961 ret = timeout; 962 msg_ptr = NULL; 963 } else { 964 wait.task = current; 965 wait.state = STATE_NONE; 966 ret = wq_sleep(info, RECV, timeout, &wait); 967 msg_ptr = wait.msg; 968 } 969 } else { 970 msg_ptr = msg_get(info); 971 972 inode->i_atime = inode->i_mtime = inode->i_ctime = 973 CURRENT_TIME; 974 975 /* There is now free space in queue. */ 976 pipelined_receive(info); 977 spin_unlock(&info->lock); 978 ret = 0; 979 } 980 if (ret == 0) { 981 ret = msg_ptr->m_ts; 982 983 if ((u_msg_prio && put_user(msg_ptr->m_type, u_msg_prio)) || 984 store_msg(u_msg_ptr, msg_ptr, msg_ptr->m_ts)) { 985 ret = -EFAULT; 986 } 987 free_msg(msg_ptr); 988 } 989out_fput: 990 fput(filp); 991out: 992 return ret; 993} 994 995/* 996 * Notes: the case when user wants us to deregister (with NULL as pointer) 997 * and he isn't currently owner of notification, will be silently discarded. 998 * It isn't explicitly defined in the POSIX. 999 */ 1000SYSCALL_DEFINE2(mq_notify, mqd_t, mqdes, 1001 const struct sigevent __user *, u_notification) 1002{ 1003 int ret; 1004 struct file *filp; 1005 struct sock *sock; 1006 struct inode *inode; 1007 struct sigevent notification; 1008 struct mqueue_inode_info *info; 1009 struct sk_buff *nc; 1010 1011 if (u_notification) { 1012 if (copy_from_user(¬ification, u_notification, 1013 sizeof(struct sigevent))) 1014 return -EFAULT; 1015 } 1016 1017 audit_mq_notify(mqdes, u_notification ? ¬ification : NULL); 1018 1019 nc = NULL; 1020 sock = NULL; 1021 if (u_notification != NULL) { 1022 if (unlikely(notification.sigev_notify != SIGEV_NONE && 1023 notification.sigev_notify != SIGEV_SIGNAL && 1024 notification.sigev_notify != SIGEV_THREAD)) 1025 return -EINVAL; 1026 if (notification.sigev_notify == SIGEV_SIGNAL && 1027 !valid_signal(notification.sigev_signo)) { 1028 return -EINVAL; 1029 } 1030 if (notification.sigev_notify == SIGEV_THREAD) { 1031 long timeo; 1032 1033 /* create the notify skb */ 1034 nc = alloc_skb(NOTIFY_COOKIE_LEN, GFP_KERNEL); 1035 ret = -ENOMEM; 1036 if (!nc) 1037 goto out; 1038 ret = -EFAULT; 1039 if (copy_from_user(nc->data, 1040 notification.sigev_value.sival_ptr, 1041 NOTIFY_COOKIE_LEN)) { 1042 goto out; 1043 } 1044 1045 /* TODO: add a header? */ 1046 skb_put(nc, NOTIFY_COOKIE_LEN); 1047 /* and attach it to the socket */ 1048retry: 1049 filp = fget(notification.sigev_signo); 1050 ret = -EBADF; 1051 if (!filp) 1052 goto out; 1053 sock = netlink_getsockbyfilp(filp); 1054 fput(filp); 1055 if (IS_ERR(sock)) { 1056 ret = PTR_ERR(sock); 1057 sock = NULL; 1058 goto out; 1059 } 1060 1061 timeo = MAX_SCHEDULE_TIMEOUT; 1062 ret = netlink_attachskb(sock, nc, &timeo, NULL); 1063 if (ret == 1) 1064 goto retry; 1065 if (ret) { 1066 sock = NULL; 1067 nc = NULL; 1068 goto out; 1069 } 1070 } 1071 } 1072 1073 ret = -EBADF; 1074 filp = fget(mqdes); 1075 if (!filp) 1076 goto out; 1077 1078 inode = filp->f_path.dentry->d_inode; 1079 if (unlikely(filp->f_op != &mqueue_file_operations)) 1080 goto out_fput; 1081 info = MQUEUE_I(inode); 1082 1083 ret = 0; 1084 spin_lock(&info->lock); 1085 if (u_notification == NULL) { 1086 if (info->notify_owner == task_tgid(current)) { 1087 remove_notification(info); 1088 inode->i_atime = inode->i_ctime = CURRENT_TIME; 1089 } 1090 } else if (info->notify_owner != NULL) { 1091 ret = -EBUSY; 1092 } else { 1093 switch (notification.sigev_notify) { 1094 case SIGEV_NONE: 1095 info->notify.sigev_notify = SIGEV_NONE; 1096 break; 1097 case SIGEV_THREAD: 1098 info->notify_sock = sock; 1099 info->notify_cookie = nc; 1100 sock = NULL; 1101 nc = NULL; 1102 info->notify.sigev_notify = SIGEV_THREAD; 1103 break; 1104 case SIGEV_SIGNAL: 1105 info->notify.sigev_signo = notification.sigev_signo; 1106 info->notify.sigev_value = notification.sigev_value; 1107 info->notify.sigev_notify = SIGEV_SIGNAL; 1108 break; 1109 } 1110 1111 info->notify_owner = get_pid(task_tgid(current)); 1112 inode->i_atime = inode->i_ctime = CURRENT_TIME; 1113 } 1114 spin_unlock(&info->lock); 1115out_fput: 1116 fput(filp); 1117out: 1118 if (sock) { 1119 netlink_detachskb(sock, nc); 1120 } else if (nc) { 1121 dev_kfree_skb(nc); 1122 } 1123 return ret; 1124} 1125 1126SYSCALL_DEFINE3(mq_getsetattr, mqd_t, mqdes, 1127 const struct mq_attr __user *, u_mqstat, 1128 struct mq_attr __user *, u_omqstat) 1129{ 1130 int ret; 1131 struct mq_attr mqstat, omqstat; 1132 struct file *filp; 1133 struct inode *inode; 1134 struct mqueue_inode_info *info; 1135 1136 if (u_mqstat != NULL) { 1137 if (copy_from_user(&mqstat, u_mqstat, sizeof(struct mq_attr))) 1138 return -EFAULT; 1139 if (mqstat.mq_flags & (~O_NONBLOCK)) 1140 return -EINVAL; 1141 } 1142 1143 ret = -EBADF; 1144 filp = fget(mqdes); 1145 if (!filp) 1146 goto out; 1147 1148 inode = filp->f_path.dentry->d_inode; 1149 if (unlikely(filp->f_op != &mqueue_file_operations)) 1150 goto out_fput; 1151 info = MQUEUE_I(inode); 1152 1153 spin_lock(&info->lock); 1154 1155 omqstat = info->attr; 1156 omqstat.mq_flags = filp->f_flags & O_NONBLOCK; 1157 if (u_mqstat) { 1158 audit_mq_getsetattr(mqdes, &mqstat); 1159 if (mqstat.mq_flags & O_NONBLOCK) 1160 filp->f_flags |= O_NONBLOCK; 1161 else 1162 filp->f_flags &= ~O_NONBLOCK; 1163 1164 inode->i_atime = inode->i_ctime = CURRENT_TIME; 1165 } 1166 1167 spin_unlock(&info->lock); 1168 1169 ret = 0; 1170 if (u_omqstat != NULL && copy_to_user(u_omqstat, &omqstat, 1171 sizeof(struct mq_attr))) 1172 ret = -EFAULT; 1173 1174out_fput: 1175 fput(filp); 1176out: 1177 return ret; 1178} 1179 1180static const struct inode_operations mqueue_dir_inode_operations = { 1181 .lookup = simple_lookup, 1182 .create = mqueue_create, 1183 .unlink = mqueue_unlink, 1184}; 1185 1186static const struct file_operations mqueue_file_operations = { 1187 .flush = mqueue_flush_file, 1188 .poll = mqueue_poll_file, 1189 .read = mqueue_read_file, 1190}; 1191 1192static struct super_operations mqueue_super_ops = { 1193 .alloc_inode = mqueue_alloc_inode, 1194 .destroy_inode = mqueue_destroy_inode, 1195 .statfs = simple_statfs, 1196 .delete_inode = mqueue_delete_inode, 1197 .drop_inode = generic_delete_inode, 1198}; 1199 1200static struct file_system_type mqueue_fs_type = { 1201 .name = "mqueue", 1202 .get_sb = mqueue_get_sb, 1203 .kill_sb = kill_litter_super, 1204}; 1205 1206static int msg_max_limit_min = MIN_MSGMAX; 1207static int msg_max_limit_max = MAX_MSGMAX; 1208 1209static int msg_maxsize_limit_min = MIN_MSGSIZEMAX; 1210static int msg_maxsize_limit_max = MAX_MSGSIZEMAX; 1211 1212static ctl_table mq_sysctls[] = { 1213 { 1214 .procname = "queues_max", 1215 .data = &queues_max, 1216 .maxlen = sizeof(int), 1217 .mode = 0644, 1218 .proc_handler = &proc_dointvec, 1219 }, 1220 { 1221 .procname = "msg_max", 1222 .data = &msg_max, 1223 .maxlen = sizeof(int), 1224 .mode = 0644, 1225 .proc_handler = &proc_dointvec_minmax, 1226 .extra1 = &msg_max_limit_min, 1227 .extra2 = &msg_max_limit_max, 1228 }, 1229 { 1230 .procname = "msgsize_max", 1231 .data = &msgsize_max, 1232 .maxlen = sizeof(int), 1233 .mode = 0644, 1234 .proc_handler = &proc_dointvec_minmax, 1235 .extra1 = &msg_maxsize_limit_min, 1236 .extra2 = &msg_maxsize_limit_max, 1237 }, 1238 { .ctl_name = 0 } 1239}; 1240 1241static ctl_table mq_sysctl_dir[] = { 1242 { 1243 .procname = "mqueue", 1244 .mode = 0555, 1245 .child = mq_sysctls, 1246 }, 1247 { .ctl_name = 0 } 1248}; 1249 1250static ctl_table mq_sysctl_root[] = { 1251 { 1252 .ctl_name = CTL_FS, 1253 .procname = "fs", 1254 .mode = 0555, 1255 .child = mq_sysctl_dir, 1256 }, 1257 { .ctl_name = 0 } 1258}; 1259 1260static int __init init_mqueue_fs(void) 1261{ 1262 int error; 1263 1264 mqueue_inode_cachep = kmem_cache_create("mqueue_inode_cache", 1265 sizeof(struct mqueue_inode_info), 0, 1266 SLAB_HWCACHE_ALIGN, init_once); 1267 if (mqueue_inode_cachep == NULL) 1268 return -ENOMEM; 1269 1270 /* ignore failues - they are not fatal */ 1271 mq_sysctl_table = register_sysctl_table(mq_sysctl_root); 1272 1273 error = register_filesystem(&mqueue_fs_type); 1274 if (error) 1275 goto out_sysctl; 1276 1277 if (IS_ERR(mqueue_mnt = kern_mount(&mqueue_fs_type))) { 1278 error = PTR_ERR(mqueue_mnt); 1279 goto out_filesystem; 1280 } 1281 1282 /* internal initialization - not common for vfs */ 1283 queues_count = 0; 1284 spin_lock_init(&mq_lock); 1285 1286 return 0; 1287 1288out_filesystem: 1289 unregister_filesystem(&mqueue_fs_type); 1290out_sysctl: 1291 if (mq_sysctl_table) 1292 unregister_sysctl_table(mq_sysctl_table); 1293 kmem_cache_destroy(mqueue_inode_cachep); 1294 return error; 1295} 1296 1297__initcall(init_mqueue_fs); 1298