fs/autofs/root.c

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This source file includes following definitions.
autofs_del_active
autofs_dir_open
autofs_dentry_release
autofs_lookup_active
autofs_lookup_expiring
autofs_mount_wait
do_expire_wait
autofs_mountpoint_changed
autofs_d_automount
autofs_d_manage
autofs_lookup
autofs_dir_symlink
autofs_dir_unlink
autofs_set_leaf_automount_flags
autofs_clear_leaf_automount_flags
autofs_dir_rmdir
autofs_dir_mkdir
autofs_compat_get_set_timeout
autofs_get_set_timeout
autofs_get_protover
autofs_get_protosubver
autofs_ask_umount
is_autofs_dentry
autofs_root_ioctl_unlocked
autofs_root_ioctl
autofs_root_compat_ioctl
   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * Copyright 1997-1998 Transmeta Corporation -- All Rights Reserved
   4  * Copyright 1999-2000 Jeremy Fitzhardinge <jeremy@goop.org>
   5  * Copyright 2001-2006 Ian Kent <raven@themaw.net>
   6  */
   7 
   8 #include <linux/capability.h>
   9 #include <linux/compat.h>
  10 
  11 #include "autofs_i.h"
  12 
  13 static int autofs_dir_symlink(struct inode *, struct dentry *, const char *);
  14 static int autofs_dir_unlink(struct inode *, struct dentry *);
  15 static int autofs_dir_rmdir(struct inode *, struct dentry *);
  16 static int autofs_dir_mkdir(struct inode *, struct dentry *, umode_t);
  17 static long autofs_root_ioctl(struct file *, unsigned int, unsigned long);
  18 #ifdef CONFIG_COMPAT
  19 static long autofs_root_compat_ioctl(struct file *,
  20                                      unsigned int, unsigned long);
  21 #endif
  22 static int autofs_dir_open(struct inode *inode, struct file *file);
  23 static struct dentry *autofs_lookup(struct inode *,
  24                                     struct dentry *, unsigned int);
  25 static struct vfsmount *autofs_d_automount(struct path *);
  26 static int autofs_d_manage(const struct path *, bool);
  27 static void autofs_dentry_release(struct dentry *);
  28 
  29 const struct file_operations autofs_root_operations = {
  30         .open           = dcache_dir_open,
  31         .release        = dcache_dir_close,
  32         .read           = generic_read_dir,
  33         .iterate_shared = dcache_readdir,
  34         .llseek         = dcache_dir_lseek,
  35         .unlocked_ioctl = autofs_root_ioctl,
  36 #ifdef CONFIG_COMPAT
  37         .compat_ioctl   = autofs_root_compat_ioctl,
  38 #endif
  39 };
  40 
  41 const struct file_operations autofs_dir_operations = {
  42         .open           = autofs_dir_open,
  43         .release        = dcache_dir_close,
  44         .read           = generic_read_dir,
  45         .iterate_shared = dcache_readdir,
  46         .llseek         = dcache_dir_lseek,
  47 };
  48 
  49 const struct inode_operations autofs_dir_inode_operations = {
  50         .lookup         = autofs_lookup,
  51         .unlink         = autofs_dir_unlink,
  52         .symlink        = autofs_dir_symlink,
  53         .mkdir          = autofs_dir_mkdir,
  54         .rmdir          = autofs_dir_rmdir,
  55 };
  56 
  57 const struct dentry_operations autofs_dentry_operations = {
  58         .d_automount    = autofs_d_automount,
  59         .d_manage       = autofs_d_manage,
  60         .d_release      = autofs_dentry_release,
  61 };
  62 
  63 static void autofs_del_active(struct dentry *dentry)
  64 {
  65         struct autofs_sb_info *sbi = autofs_sbi(dentry->d_sb);
  66         struct autofs_info *ino;
  67 
  68         ino = autofs_dentry_ino(dentry);
  69         spin_lock(&sbi->lookup_lock);
  70         list_del_init(&ino->active);
  71         spin_unlock(&sbi->lookup_lock);
  72 }
  73 
  74 static int autofs_dir_open(struct inode *inode, struct file *file)
  75 {
  76         struct dentry *dentry = file->f_path.dentry;
  77         struct autofs_sb_info *sbi = autofs_sbi(dentry->d_sb);
  78 
  79         pr_debug("file=%p dentry=%p %pd\n", file, dentry, dentry);
  80 
  81         if (autofs_oz_mode(sbi))
  82                 goto out;
  83 
  84         /*
  85          * An empty directory in an autofs file system is always a
  86          * mount point. The daemon must have failed to mount this
  87          * during lookup so it doesn't exist. This can happen, for
  88          * example, if user space returns an incorrect status for a
  89          * mount request. Otherwise we're doing a readdir on the
  90          * autofs file system so just let the libfs routines handle
  91          * it.
  92          */
  93         spin_lock(&sbi->lookup_lock);
  94         if (!path_is_mountpoint(&file->f_path) && simple_empty(dentry)) {
  95                 spin_unlock(&sbi->lookup_lock);
  96                 return -ENOENT;
  97         }
  98         spin_unlock(&sbi->lookup_lock);
  99 
 100 out:
 101         return dcache_dir_open(inode, file);
 102 }
 103 
 104 static void autofs_dentry_release(struct dentry *de)
 105 {
 106         struct autofs_info *ino = autofs_dentry_ino(de);
 107         struct autofs_sb_info *sbi = autofs_sbi(de->d_sb);
 108 
 109         pr_debug("releasing %p\n", de);
 110 
 111         if (!ino)
 112                 return;
 113 
 114         if (sbi) {
 115                 spin_lock(&sbi->lookup_lock);
 116                 if (!list_empty(&ino->active))
 117                         list_del(&ino->active);
 118                 if (!list_empty(&ino->expiring))
 119                         list_del(&ino->expiring);
 120                 spin_unlock(&sbi->lookup_lock);
 121         }
 122 
 123         autofs_free_ino(ino);
 124 }
 125 
 126 static struct dentry *autofs_lookup_active(struct dentry *dentry)
 127 {
 128         struct autofs_sb_info *sbi = autofs_sbi(dentry->d_sb);
 129         struct dentry *parent = dentry->d_parent;
 130         const struct qstr *name = &dentry->d_name;
 131         unsigned int len = name->len;
 132         unsigned int hash = name->hash;
 133         const unsigned char *str = name->name;
 134         struct list_head *p, *head;
 135 
 136         head = &sbi->active_list;
 137         if (list_empty(head))
 138                 return NULL;
 139         spin_lock(&sbi->lookup_lock);
 140         list_for_each(p, head) {
 141                 struct autofs_info *ino;
 142                 struct dentry *active;
 143                 const struct qstr *qstr;
 144 
 145                 ino = list_entry(p, struct autofs_info, active);
 146                 active = ino->dentry;
 147 
 148                 spin_lock(&active->d_lock);
 149 
 150                 /* Already gone? */
 151                 if ((int) d_count(active) <= 0)
 152                         goto next;
 153 
 154                 qstr = &active->d_name;
 155 
 156                 if (active->d_name.hash != hash)
 157                         goto next;
 158                 if (active->d_parent != parent)
 159                         goto next;
 160 
 161                 if (qstr->len != len)
 162                         goto next;
 163                 if (memcmp(qstr->name, str, len))
 164                         goto next;
 165 
 166                 if (d_unhashed(active)) {
 167                         dget_dlock(active);
 168                         spin_unlock(&active->d_lock);
 169                         spin_unlock(&sbi->lookup_lock);
 170                         return active;
 171                 }
 172 next:
 173                 spin_unlock(&active->d_lock);
 174         }
 175         spin_unlock(&sbi->lookup_lock);
 176 
 177         return NULL;
 178 }
 179 
 180 static struct dentry *autofs_lookup_expiring(struct dentry *dentry,
 181                                              bool rcu_walk)
 182 {
 183         struct autofs_sb_info *sbi = autofs_sbi(dentry->d_sb);
 184         struct dentry *parent = dentry->d_parent;
 185         const struct qstr *name = &dentry->d_name;
 186         unsigned int len = name->len;
 187         unsigned int hash = name->hash;
 188         const unsigned char *str = name->name;
 189         struct list_head *p, *head;
 190 
 191         head = &sbi->expiring_list;
 192         if (list_empty(head))
 193                 return NULL;
 194         spin_lock(&sbi->lookup_lock);
 195         list_for_each(p, head) {
 196                 struct autofs_info *ino;
 197                 struct dentry *expiring;
 198                 const struct qstr *qstr;
 199 
 200                 if (rcu_walk) {
 201                         spin_unlock(&sbi->lookup_lock);
 202                         return ERR_PTR(-ECHILD);
 203                 }
 204 
 205                 ino = list_entry(p, struct autofs_info, expiring);
 206                 expiring = ino->dentry;
 207 
 208                 spin_lock(&expiring->d_lock);
 209 
 210                 /* We've already been dentry_iput or unlinked */
 211                 if (d_really_is_negative(expiring))
 212                         goto next;
 213 
 214                 qstr = &expiring->d_name;
 215 
 216                 if (expiring->d_name.hash != hash)
 217                         goto next;
 218                 if (expiring->d_parent != parent)
 219                         goto next;
 220 
 221                 if (qstr->len != len)
 222                         goto next;
 223                 if (memcmp(qstr->name, str, len))
 224                         goto next;
 225 
 226                 if (d_unhashed(expiring)) {
 227                         dget_dlock(expiring);
 228                         spin_unlock(&expiring->d_lock);
 229                         spin_unlock(&sbi->lookup_lock);
 230                         return expiring;
 231                 }
 232 next:
 233                 spin_unlock(&expiring->d_lock);
 234         }
 235         spin_unlock(&sbi->lookup_lock);
 236 
 237         return NULL;
 238 }
 239 
 240 static int autofs_mount_wait(const struct path *path, bool rcu_walk)
 241 {
 242         struct autofs_sb_info *sbi = autofs_sbi(path->dentry->d_sb);
 243         struct autofs_info *ino = autofs_dentry_ino(path->dentry);
 244         int status = 0;
 245 
 246         if (ino->flags & AUTOFS_INF_PENDING) {
 247                 if (rcu_walk)
 248                         return -ECHILD;
 249                 pr_debug("waiting for mount name=%pd\n", path->dentry);
 250                 status = autofs_wait(sbi, path, NFY_MOUNT);
 251                 pr_debug("mount wait done status=%d\n", status);
 252                 ino->last_used = jiffies;
 253                 return status;
 254         }
 255         if (!(sbi->flags & AUTOFS_SBI_STRICTEXPIRE))
 256                 ino->last_used = jiffies;
 257         return status;
 258 }
 259 
 260 static int do_expire_wait(const struct path *path, bool rcu_walk)
 261 {
 262         struct dentry *dentry = path->dentry;
 263         struct dentry *expiring;
 264 
 265         expiring = autofs_lookup_expiring(dentry, rcu_walk);
 266         if (IS_ERR(expiring))
 267                 return PTR_ERR(expiring);
 268         if (!expiring)
 269                 return autofs_expire_wait(path, rcu_walk);
 270         else {
 271                 const struct path this = { .mnt = path->mnt, .dentry = expiring };
 272                 /*
 273                  * If we are racing with expire the request might not
 274                  * be quite complete, but the directory has been removed
 275                  * so it must have been successful, just wait for it.
 276                  */
 277                 autofs_expire_wait(&this, 0);
 278                 autofs_del_expiring(expiring);
 279                 dput(expiring);
 280         }
 281         return 0;
 282 }
 283 
 284 static struct dentry *autofs_mountpoint_changed(struct path *path)
 285 {
 286         struct dentry *dentry = path->dentry;
 287         struct autofs_sb_info *sbi = autofs_sbi(dentry->d_sb);
 288 
 289         /*
 290          * If this is an indirect mount the dentry could have gone away
 291          * as a result of an expire and a new one created.
 292          */
 293         if (autofs_type_indirect(sbi->type) && d_unhashed(dentry)) {
 294                 struct dentry *parent = dentry->d_parent;
 295                 struct autofs_info *ino;
 296                 struct dentry *new;
 297 
 298                 new = d_lookup(parent, &dentry->d_name);
 299                 if (!new)
 300                         return NULL;
 301                 ino = autofs_dentry_ino(new);
 302                 ino->last_used = jiffies;
 303                 dput(path->dentry);
 304                 path->dentry = new;
 305         }
 306         return path->dentry;
 307 }
 308 
 309 static struct vfsmount *autofs_d_automount(struct path *path)
 310 {
 311         struct dentry *dentry = path->dentry;
 312         struct autofs_sb_info *sbi = autofs_sbi(dentry->d_sb);
 313         struct autofs_info *ino = autofs_dentry_ino(dentry);
 314         int status;
 315 
 316         pr_debug("dentry=%p %pd\n", dentry, dentry);
 317 
 318         /* The daemon never triggers a mount. */
 319         if (autofs_oz_mode(sbi))
 320                 return NULL;
 321 
 322         /*
 323          * If an expire request is pending everyone must wait.
 324          * If the expire fails we're still mounted so continue
 325          * the follow and return. A return of -EAGAIN (which only
 326          * happens with indirect mounts) means the expire completed
 327          * and the directory was removed, so just go ahead and try
 328          * the mount.
 329          */
 330         status = do_expire_wait(path, 0);
 331         if (status && status != -EAGAIN)
 332                 return NULL;
 333 
 334         /* Callback to the daemon to perform the mount or wait */
 335         spin_lock(&sbi->fs_lock);
 336         if (ino->flags & AUTOFS_INF_PENDING) {
 337                 spin_unlock(&sbi->fs_lock);
 338                 status = autofs_mount_wait(path, 0);
 339                 if (status)
 340                         return ERR_PTR(status);
 341                 goto done;
 342         }
 343 
 344         /*
 345          * If the dentry is a symlink it's equivalent to a directory
 346          * having path_is_mountpoint() true, so there's no need to call
 347          * back to the daemon.
 348          */
 349         if (d_really_is_positive(dentry) && d_is_symlink(dentry)) {
 350                 spin_unlock(&sbi->fs_lock);
 351                 goto done;
 352         }
 353 
 354         if (!path_is_mountpoint(path)) {
 355                 /*
 356                  * It's possible that user space hasn't removed directories
 357                  * after umounting a rootless multi-mount, although it
 358                  * should. For v5 path_has_submounts() is sufficient to
 359                  * handle this because the leaves of the directory tree under
 360                  * the mount never trigger mounts themselves (they have an
 361                  * autofs trigger mount mounted on them). But v4 pseudo direct
 362                  * mounts do need the leaves to trigger mounts. In this case
 363                  * we have no choice but to use the list_empty() check and
 364                  * require user space behave.
 365                  */
 366                 if (sbi->version > 4) {
 367                         if (path_has_submounts(path)) {
 368                                 spin_unlock(&sbi->fs_lock);
 369                                 goto done;
 370                         }
 371                 } else {
 372                         if (!simple_empty(dentry)) {
 373                                 spin_unlock(&sbi->fs_lock);
 374                                 goto done;
 375                         }
 376                 }
 377                 ino->flags |= AUTOFS_INF_PENDING;
 378                 spin_unlock(&sbi->fs_lock);
 379                 status = autofs_mount_wait(path, 0);
 380                 spin_lock(&sbi->fs_lock);
 381                 ino->flags &= ~AUTOFS_INF_PENDING;
 382                 if (status) {
 383                         spin_unlock(&sbi->fs_lock);
 384                         return ERR_PTR(status);
 385                 }
 386         }
 387         spin_unlock(&sbi->fs_lock);
 388 done:
 389         /* Mount succeeded, check if we ended up with a new dentry */
 390         dentry = autofs_mountpoint_changed(path);
 391         if (!dentry)
 392                 return ERR_PTR(-ENOENT);
 393 
 394         return NULL;
 395 }
 396 
 397 static int autofs_d_manage(const struct path *path, bool rcu_walk)
 398 {
 399         struct dentry *dentry = path->dentry;
 400         struct autofs_sb_info *sbi = autofs_sbi(dentry->d_sb);
 401         struct autofs_info *ino = autofs_dentry_ino(dentry);
 402         int status;
 403 
 404         pr_debug("dentry=%p %pd\n", dentry, dentry);
 405 
 406         /* The daemon never waits. */
 407         if (autofs_oz_mode(sbi)) {
 408                 if (!path_is_mountpoint(path))
 409                         return -EISDIR;
 410                 return 0;
 411         }
 412 
 413         /* Wait for pending expires */
 414         if (do_expire_wait(path, rcu_walk) == -ECHILD)
 415                 return -ECHILD;
 416 
 417         /*
 418          * This dentry may be under construction so wait on mount
 419          * completion.
 420          */
 421         status = autofs_mount_wait(path, rcu_walk);
 422         if (status)
 423                 return status;
 424 
 425         if (rcu_walk) {
 426                 /* We don't need fs_lock in rcu_walk mode,
 427                  * just testing 'AUTOFS_INFO_NO_RCU' is enough.
 428                  * simple_empty() takes a spinlock, so leave it
 429                  * to last.
 430                  * We only return -EISDIR when certain this isn't
 431                  * a mount-trap.
 432                  */
 433                 struct inode *inode;
 434 
 435                 if (ino->flags & AUTOFS_INF_WANT_EXPIRE)
 436                         return 0;
 437                 if (path_is_mountpoint(path))
 438                         return 0;
 439                 inode = d_inode_rcu(dentry);
 440                 if (inode && S_ISLNK(inode->i_mode))
 441                         return -EISDIR;
 442                 if (list_empty(&dentry->d_subdirs))
 443                         return 0;
 444                 if (!simple_empty(dentry))
 445                         return -EISDIR;
 446                 return 0;
 447         }
 448 
 449         spin_lock(&sbi->fs_lock);
 450         /*
 451          * If the dentry has been selected for expire while we slept
 452          * on the lock then it might go away. We'll deal with that in
 453          * ->d_automount() and wait on a new mount if the expire
 454          * succeeds or return here if it doesn't (since there's no
 455          * mount to follow with a rootless multi-mount).
 456          */
 457         if (!(ino->flags & AUTOFS_INF_EXPIRING)) {
 458                 /*
 459                  * Any needed mounting has been completed and the path
 460                  * updated so check if this is a rootless multi-mount so
 461                  * we can avoid needless calls ->d_automount() and avoid
 462                  * an incorrect ELOOP error return.
 463                  */
 464                 if ((!path_is_mountpoint(path) && !simple_empty(dentry)) ||
 465                     (d_really_is_positive(dentry) && d_is_symlink(dentry)))
 466                         status = -EISDIR;
 467         }
 468         spin_unlock(&sbi->fs_lock);
 469 
 470         return status;
 471 }
 472 
 473 /* Lookups in the root directory */
 474 static struct dentry *autofs_lookup(struct inode *dir,
 475                                     struct dentry *dentry, unsigned int flags)
 476 {
 477         struct autofs_sb_info *sbi;
 478         struct autofs_info *ino;
 479         struct dentry *active;
 480 
 481         pr_debug("name = %pd\n", dentry);
 482 
 483         /* File name too long to exist */
 484         if (dentry->d_name.len > NAME_MAX)
 485                 return ERR_PTR(-ENAMETOOLONG);
 486 
 487         sbi = autofs_sbi(dir->i_sb);
 488 
 489         pr_debug("pid = %u, pgrp = %u, catatonic = %d, oz_mode = %d\n",
 490                  current->pid, task_pgrp_nr(current),
 491                  sbi->flags & AUTOFS_SBI_CATATONIC,
 492                  autofs_oz_mode(sbi));
 493 
 494         active = autofs_lookup_active(dentry);
 495         if (active)
 496                 return active;
 497         else {
 498                 /*
 499                  * A dentry that is not within the root can never trigger a
 500                  * mount operation, unless the directory already exists, so we
 501                  * can return fail immediately.  The daemon however does need
 502                  * to create directories within the file system.
 503                  */
 504                 if (!autofs_oz_mode(sbi) && !IS_ROOT(dentry->d_parent))
 505                         return ERR_PTR(-ENOENT);
 506 
 507                 ino = autofs_new_ino(sbi);
 508                 if (!ino)
 509                         return ERR_PTR(-ENOMEM);
 510 
 511                 spin_lock(&sbi->lookup_lock);
 512                 spin_lock(&dentry->d_lock);
 513                 /* Mark entries in the root as mount triggers */
 514                 if (IS_ROOT(dentry->d_parent) &&
 515                     autofs_type_indirect(sbi->type))
 516                         __managed_dentry_set_managed(dentry);
 517                 dentry->d_fsdata = ino;
 518                 ino->dentry = dentry;
 519 
 520                 list_add(&ino->active, &sbi->active_list);
 521                 spin_unlock(&sbi->lookup_lock);
 522                 spin_unlock(&dentry->d_lock);
 523         }
 524         return NULL;
 525 }
 526 
 527 static int autofs_dir_symlink(struct inode *dir,
 528                                struct dentry *dentry,
 529                                const char *symname)
 530 {
 531         struct autofs_sb_info *sbi = autofs_sbi(dir->i_sb);
 532         struct autofs_info *ino = autofs_dentry_ino(dentry);
 533         struct autofs_info *p_ino;
 534         struct inode *inode;
 535         size_t size = strlen(symname);
 536         char *cp;
 537 
 538         pr_debug("%s <- %pd\n", symname, dentry);
 539 
 540         if (!autofs_oz_mode(sbi))
 541                 return -EACCES;
 542 
 543         /* autofs_oz_mode() needs to allow path walks when the
 544          * autofs mount is catatonic but the state of an autofs
 545          * file system needs to be preserved over restarts.
 546          */
 547         if (sbi->flags & AUTOFS_SBI_CATATONIC)
 548                 return -EACCES;
 549 
 550         BUG_ON(!ino);
 551 
 552         autofs_clean_ino(ino);
 553 
 554         autofs_del_active(dentry);
 555 
 556         cp = kmalloc(size + 1, GFP_KERNEL);
 557         if (!cp)
 558                 return -ENOMEM;
 559 
 560         strcpy(cp, symname);
 561 
 562         inode = autofs_get_inode(dir->i_sb, S_IFLNK | 0555);
 563         if (!inode) {
 564                 kfree(cp);
 565                 return -ENOMEM;
 566         }
 567         inode->i_private = cp;
 568         inode->i_size = size;
 569         d_add(dentry, inode);
 570 
 571         dget(dentry);
 572         atomic_inc(&ino->count);
 573         p_ino = autofs_dentry_ino(dentry->d_parent);
 574         if (p_ino && !IS_ROOT(dentry))
 575                 atomic_inc(&p_ino->count);
 576 
 577         dir->i_mtime = current_time(dir);
 578 
 579         return 0;
 580 }
 581 
 582 /*
 583  * NOTE!
 584  *
 585  * Normal filesystems would do a "d_delete()" to tell the VFS dcache
 586  * that the file no longer exists. However, doing that means that the
 587  * VFS layer can turn the dentry into a negative dentry.  We don't want
 588  * this, because the unlink is probably the result of an expire.
 589  * We simply d_drop it and add it to a expiring list in the super block,
 590  * which allows the dentry lookup to check for an incomplete expire.
 591  *
 592  * If a process is blocked on the dentry waiting for the expire to finish,
 593  * it will invalidate the dentry and try to mount with a new one.
 594  *
 595  * Also see autofs_dir_rmdir()..
 596  */
 597 static int autofs_dir_unlink(struct inode *dir, struct dentry *dentry)
 598 {
 599         struct autofs_sb_info *sbi = autofs_sbi(dir->i_sb);
 600         struct autofs_info *ino = autofs_dentry_ino(dentry);
 601         struct autofs_info *p_ino;
 602 
 603         if (!autofs_oz_mode(sbi))
 604                 return -EACCES;
 605 
 606         /* autofs_oz_mode() needs to allow path walks when the
 607          * autofs mount is catatonic but the state of an autofs
 608          * file system needs to be preserved over restarts.
 609          */
 610         if (sbi->flags & AUTOFS_SBI_CATATONIC)
 611                 return -EACCES;
 612 
 613         if (atomic_dec_and_test(&ino->count)) {
 614                 p_ino = autofs_dentry_ino(dentry->d_parent);
 615                 if (p_ino && !IS_ROOT(dentry))
 616                         atomic_dec(&p_ino->count);
 617         }
 618         dput(ino->dentry);
 619 
 620         d_inode(dentry)->i_size = 0;
 621         clear_nlink(d_inode(dentry));
 622 
 623         dir->i_mtime = current_time(dir);
 624 
 625         spin_lock(&sbi->lookup_lock);
 626         __autofs_add_expiring(dentry);
 627         d_drop(dentry);
 628         spin_unlock(&sbi->lookup_lock);
 629 
 630         return 0;
 631 }
 632 
 633 /*
 634  * Version 4 of autofs provides a pseudo direct mount implementation
 635  * that relies on directories at the leaves of a directory tree under
 636  * an indirect mount to trigger mounts. To allow for this we need to
 637  * set the DMANAGED_AUTOMOUNT and DMANAGED_TRANSIT flags on the leaves
 638  * of the directory tree. There is no need to clear the automount flag
 639  * following a mount or restore it after an expire because these mounts
 640  * are always covered. However, it is necessary to ensure that these
 641  * flags are clear on non-empty directories to avoid unnecessary calls
 642  * during path walks.
 643  */
 644 static void autofs_set_leaf_automount_flags(struct dentry *dentry)
 645 {
 646         struct dentry *parent;
 647 
 648         /* root and dentrys in the root are already handled */
 649         if (IS_ROOT(dentry->d_parent))
 650                 return;
 651 
 652         managed_dentry_set_managed(dentry);
 653 
 654         parent = dentry->d_parent;
 655         /* only consider parents below dentrys in the root */
 656         if (IS_ROOT(parent->d_parent))
 657                 return;
 658         managed_dentry_clear_managed(parent);
 659 }
 660 
 661 static void autofs_clear_leaf_automount_flags(struct dentry *dentry)
 662 {
 663         struct list_head *d_child;
 664         struct dentry *parent;
 665 
 666         /* flags for dentrys in the root are handled elsewhere */
 667         if (IS_ROOT(dentry->d_parent))
 668                 return;
 669 
 670         managed_dentry_clear_managed(dentry);
 671 
 672         parent = dentry->d_parent;
 673         /* only consider parents below dentrys in the root */
 674         if (IS_ROOT(parent->d_parent))
 675                 return;
 676         d_child = &dentry->d_child;
 677         /* Set parent managed if it's becoming empty */
 678         if (d_child->next == &parent->d_subdirs &&
 679             d_child->prev == &parent->d_subdirs)
 680                 managed_dentry_set_managed(parent);
 681 }
 682 
 683 static int autofs_dir_rmdir(struct inode *dir, struct dentry *dentry)
 684 {
 685         struct autofs_sb_info *sbi = autofs_sbi(dir->i_sb);
 686         struct autofs_info *ino = autofs_dentry_ino(dentry);
 687         struct autofs_info *p_ino;
 688 
 689         pr_debug("dentry %p, removing %pd\n", dentry, dentry);
 690 
 691         if (!autofs_oz_mode(sbi))
 692                 return -EACCES;
 693 
 694         /* autofs_oz_mode() needs to allow path walks when the
 695          * autofs mount is catatonic but the state of an autofs
 696          * file system needs to be preserved over restarts.
 697          */
 698         if (sbi->flags & AUTOFS_SBI_CATATONIC)
 699                 return -EACCES;
 700 
 701         spin_lock(&sbi->lookup_lock);
 702         if (!simple_empty(dentry)) {
 703                 spin_unlock(&sbi->lookup_lock);
 704                 return -ENOTEMPTY;
 705         }
 706         __autofs_add_expiring(dentry);
 707         d_drop(dentry);
 708         spin_unlock(&sbi->lookup_lock);
 709 
 710         if (sbi->version < 5)
 711                 autofs_clear_leaf_automount_flags(dentry);
 712 
 713         if (atomic_dec_and_test(&ino->count)) {
 714                 p_ino = autofs_dentry_ino(dentry->d_parent);
 715                 if (p_ino && dentry->d_parent != dentry)
 716                         atomic_dec(&p_ino->count);
 717         }
 718         dput(ino->dentry);
 719         d_inode(dentry)->i_size = 0;
 720         clear_nlink(d_inode(dentry));
 721 
 722         if (dir->i_nlink)
 723                 drop_nlink(dir);
 724 
 725         return 0;
 726 }
 727 
 728 static int autofs_dir_mkdir(struct inode *dir,
 729                             struct dentry *dentry, umode_t mode)
 730 {
 731         struct autofs_sb_info *sbi = autofs_sbi(dir->i_sb);
 732         struct autofs_info *ino = autofs_dentry_ino(dentry);
 733         struct autofs_info *p_ino;
 734         struct inode *inode;
 735 
 736         if (!autofs_oz_mode(sbi))
 737                 return -EACCES;
 738 
 739         /* autofs_oz_mode() needs to allow path walks when the
 740          * autofs mount is catatonic but the state of an autofs
 741          * file system needs to be preserved over restarts.
 742          */
 743         if (sbi->flags & AUTOFS_SBI_CATATONIC)
 744                 return -EACCES;
 745 
 746         pr_debug("dentry %p, creating %pd\n", dentry, dentry);
 747 
 748         BUG_ON(!ino);
 749 
 750         autofs_clean_ino(ino);
 751 
 752         autofs_del_active(dentry);
 753 
 754         inode = autofs_get_inode(dir->i_sb, S_IFDIR | mode);
 755         if (!inode)
 756                 return -ENOMEM;
 757         d_add(dentry, inode);
 758 
 759         if (sbi->version < 5)
 760                 autofs_set_leaf_automount_flags(dentry);
 761 
 762         dget(dentry);
 763         atomic_inc(&ino->count);
 764         p_ino = autofs_dentry_ino(dentry->d_parent);
 765         if (p_ino && !IS_ROOT(dentry))
 766                 atomic_inc(&p_ino->count);
 767         inc_nlink(dir);
 768         dir->i_mtime = current_time(dir);
 769 
 770         return 0;
 771 }
 772 
 773 /* Get/set timeout ioctl() operation */
 774 #ifdef CONFIG_COMPAT
 775 static inline int autofs_compat_get_set_timeout(struct autofs_sb_info *sbi,
 776                                                  compat_ulong_t __user *p)
 777 {
 778         unsigned long ntimeout;
 779         int rv;
 780 
 781         rv = get_user(ntimeout, p);
 782         if (rv)
 783                 goto error;
 784 
 785         rv = put_user(sbi->exp_timeout/HZ, p);
 786         if (rv)
 787                 goto error;
 788 
 789         if (ntimeout > UINT_MAX/HZ)
 790                 sbi->exp_timeout = 0;
 791         else
 792                 sbi->exp_timeout = ntimeout * HZ;
 793 
 794         return 0;
 795 error:
 796         return rv;
 797 }
 798 #endif
 799 
 800 static inline int autofs_get_set_timeout(struct autofs_sb_info *sbi,
 801                                           unsigned long __user *p)
 802 {
 803         unsigned long ntimeout;
 804         int rv;
 805 
 806         rv = get_user(ntimeout, p);
 807         if (rv)
 808                 goto error;
 809 
 810         rv = put_user(sbi->exp_timeout/HZ, p);
 811         if (rv)
 812                 goto error;
 813 
 814         if (ntimeout > ULONG_MAX/HZ)
 815                 sbi->exp_timeout = 0;
 816         else
 817                 sbi->exp_timeout = ntimeout * HZ;
 818 
 819         return 0;
 820 error:
 821         return rv;
 822 }
 823 
 824 /* Return protocol version */
 825 static inline int autofs_get_protover(struct autofs_sb_info *sbi,
 826                                        int __user *p)
 827 {
 828         return put_user(sbi->version, p);
 829 }
 830 
 831 /* Return protocol sub version */
 832 static inline int autofs_get_protosubver(struct autofs_sb_info *sbi,
 833                                           int __user *p)
 834 {
 835         return put_user(sbi->sub_version, p);
 836 }
 837 
 838 /*
 839 * Tells the daemon whether it can umount the autofs mount.
 840 */
 841 static inline int autofs_ask_umount(struct vfsmount *mnt, int __user *p)
 842 {
 843         int status = 0;
 844 
 845         if (may_umount(mnt))
 846                 status = 1;
 847 
 848         pr_debug("may umount %d\n", status);
 849 
 850         status = put_user(status, p);
 851 
 852         return status;
 853 }
 854 
 855 /* Identify autofs_dentries - this is so we can tell if there's
 856  * an extra dentry refcount or not.  We only hold a refcount on the
 857  * dentry if its non-negative (ie, d_inode != NULL)
 858  */
 859 int is_autofs_dentry(struct dentry *dentry)
 860 {
 861         return dentry && d_really_is_positive(dentry) &&
 862                 dentry->d_op == &autofs_dentry_operations &&
 863                 dentry->d_fsdata != NULL;
 864 }
 865 
 866 /*
 867  * ioctl()'s on the root directory is the chief method for the daemon to
 868  * generate kernel reactions
 869  */
 870 static int autofs_root_ioctl_unlocked(struct inode *inode, struct file *filp,
 871                                        unsigned int cmd, unsigned long arg)
 872 {
 873         struct autofs_sb_info *sbi = autofs_sbi(inode->i_sb);
 874         void __user *p = (void __user *)arg;
 875 
 876         pr_debug("cmd = 0x%08x, arg = 0x%08lx, sbi = %p, pgrp = %u\n",
 877                  cmd, arg, sbi, task_pgrp_nr(current));
 878 
 879         if (_IOC_TYPE(cmd) != _IOC_TYPE(AUTOFS_IOC_FIRST) ||
 880              _IOC_NR(cmd) - _IOC_NR(AUTOFS_IOC_FIRST) >= AUTOFS_IOC_COUNT)
 881                 return -ENOTTY;
 882 
 883         if (!autofs_oz_mode(sbi) && !capable(CAP_SYS_ADMIN))
 884                 return -EPERM;
 885 
 886         switch (cmd) {
 887         case AUTOFS_IOC_READY:  /* Wait queue: go ahead and retry */
 888                 return autofs_wait_release(sbi, (autofs_wqt_t) arg, 0);
 889         case AUTOFS_IOC_FAIL:   /* Wait queue: fail with ENOENT */
 890                 return autofs_wait_release(sbi, (autofs_wqt_t) arg, -ENOENT);
 891         case AUTOFS_IOC_CATATONIC: /* Enter catatonic mode (daemon shutdown) */
 892                 autofs_catatonic_mode(sbi);
 893                 return 0;
 894         case AUTOFS_IOC_PROTOVER: /* Get protocol version */
 895                 return autofs_get_protover(sbi, p);
 896         case AUTOFS_IOC_PROTOSUBVER: /* Get protocol sub version */
 897                 return autofs_get_protosubver(sbi, p);
 898         case AUTOFS_IOC_SETTIMEOUT:
 899                 return autofs_get_set_timeout(sbi, p);
 900 #ifdef CONFIG_COMPAT
 901         case AUTOFS_IOC_SETTIMEOUT32:
 902                 return autofs_compat_get_set_timeout(sbi, p);
 903 #endif
 904 
 905         case AUTOFS_IOC_ASKUMOUNT:
 906                 return autofs_ask_umount(filp->f_path.mnt, p);
 907 
 908         /* return a single thing to expire */
 909         case AUTOFS_IOC_EXPIRE:
 910                 return autofs_expire_run(inode->i_sb, filp->f_path.mnt, sbi, p);
 911         /* same as above, but can send multiple expires through pipe */
 912         case AUTOFS_IOC_EXPIRE_MULTI:
 913                 return autofs_expire_multi(inode->i_sb,
 914                                            filp->f_path.mnt, sbi, p);
 915 
 916         default:
 917                 return -EINVAL;
 918         }
 919 }
 920 
 921 static long autofs_root_ioctl(struct file *filp,
 922                                unsigned int cmd, unsigned long arg)
 923 {
 924         struct inode *inode = file_inode(filp);
 925 
 926         return autofs_root_ioctl_unlocked(inode, filp, cmd, arg);
 927 }
 928 
 929 #ifdef CONFIG_COMPAT
 930 static long autofs_root_compat_ioctl(struct file *filp,
 931                                       unsigned int cmd, unsigned long arg)
 932 {
 933         struct inode *inode = file_inode(filp);
 934         int ret;
 935 
 936         if (cmd == AUTOFS_IOC_READY || cmd == AUTOFS_IOC_FAIL)
 937                 ret = autofs_root_ioctl_unlocked(inode, filp, cmd, arg);
 938         else
 939                 ret = autofs_root_ioctl_unlocked(inode, filp, cmd,
 940                                               (unsigned long) compat_ptr(arg));
 941 
 942         return ret;
 943 }
 944 #endif
/* [<][>][^][v][top][bottom][index][help] */
root/fs/autofs/root.c

DEFINITIONS
