fs/autofs/root.c

   1 /* -*- linux-c -*- --------------------------------------------------------- *
   2  *
   3  * linux/fs/autofs/root.c
   4  *
   5  *  Copyright 1997-1998 Transmeta Corporation -- All Rights Reserved
   6  *
   7  * This file is part of the Linux kernel and is made available under
   8  * the terms of the GNU General Public License, version 2, or at your
   9  * option, any later version, incorporated herein by reference.
  10  *
  11  * ------------------------------------------------------------------------- */
  12
  13 #include <linux/capability.h>
  14 #include <linux/errno.h>
  15 #include <linux/stat.h>
  16 #include <linux/slab.h>
  17 #include <linux/param.h>
  18 #include <linux/time.h>
  19 #include <linux/smp_lock.h>
  20 #include "autofs_i.h"
  21
  22 static int autofs_root_readdir(struct file *,void *,filldir_t);
  23 static struct dentry *autofs_root_lookup(struct inode *,struct dentry *, struct nameidata *);
  24 static int autofs_root_symlink(struct inode *,struct dentry *,const char *);
  25 static int autofs_root_unlink(struct inode *,struct dentry *);
  26 static int autofs_root_rmdir(struct inode *,struct dentry *);
  27 static int autofs_root_mkdir(struct inode *,struct dentry *,int);
  28 static int autofs_root_ioctl(struct inode *, struct file *,unsigned int,unsigned long);
  29
  30 const struct file_operations autofs_root_operations = {
  31         .read           = generic_read_dir,
  32         .readdir        = autofs_root_readdir,
  33         .ioctl          = autofs_root_ioctl,
  34 };
  35
  36 const struct inode_operations autofs_root_inode_operations = {
  37         .lookup         = autofs_root_lookup,
  38         .unlink         = autofs_root_unlink,
  39         .symlink        = autofs_root_symlink,
  40         .mkdir          = autofs_root_mkdir,
  41         .rmdir          = autofs_root_rmdir,
  42 };
  43
  44 static int autofs_root_readdir(struct file *filp, void *dirent, filldir_t filldir)
  45 {
  46         struct autofs_dir_ent *ent = NULL;
  47         struct autofs_dirhash *dirhash;
  48         struct autofs_sb_info *sbi;
  49         struct inode * inode = filp->f_path.dentry->d_inode;
  50         off_t onr, nr;
  51
  52         lock_kernel();
  53
  54         sbi = autofs_sbi(inode->i_sb);
  55         dirhash = &sbi->dirhash;
  56         nr = filp->f_pos;
  57
  58         switch(nr)
  59         {
  60         case 0:
  61                 if (filldir(dirent, ".", 1, nr, inode->i_ino, DT_DIR) < 0)
  62                         goto out;
  63                 filp->f_pos = ++nr;
  64                 /* fall through */
  65         case 1:
  66                 if (filldir(dirent, "..", 2, nr, inode->i_ino, DT_DIR) < 0)
  67                         goto out;
  68                 filp->f_pos = ++nr;
  69                 /* fall through */
  70         default:
  71                 while (onr = nr, ent = autofs_hash_enum(dirhash,&nr,ent)) {
  72                         if (!ent->dentry || d_mountpoint(ent->dentry)) {
  73                                 if (filldir(dirent,ent->name,ent->len,onr,ent->ino,DT_UNKNOWN) < 0)
  74                                         goto out;
  75                                 filp->f_pos = nr;
  76                         }
  77                 }
  78                 break;
  79         }
  80
  81 out:
  82         unlock_kernel();
  83         return 0;
  84 }
  85
  86 static int try_to_fill_dentry(struct dentry *dentry, struct super_block *sb, struct autofs_sb_info *sbi)
  87 {
  88         struct inode * inode;
  89         struct autofs_dir_ent *ent;
  90         int status = 0;
  91
  92         if (!(ent = autofs_hash_lookup(&sbi->dirhash, &dentry->d_name))) {
  93                 do {
  94                         if (status && dentry->d_inode) {
  95                                 if (status != -ENOENT)
  96                                         printk("autofs warning: lookup failure on positive dentry, status = %d, name = %s\n", status, dentry->d_name.name);
  97                                 return 0; /* Try to get the kernel to invalidate this dentry */
  98                         }
  99
 100                         /* Turn this into a real negative dentry? */
 101                         if (status == -ENOENT) {
 102                                 dentry->d_time = jiffies + AUTOFS_NEGATIVE_TIMEOUT;
 103                                 dentry->d_flags &= ~DCACHE_AUTOFS_PENDING;
 104                                 return 1;
 105                         } else if (status) {
 106                                 /* Return a negative dentry, but leave it "pending" */
 107                                 return 1;
 108                         }
 109                         status = autofs_wait(sbi, &dentry->d_name);
 110                 } while (!(ent = autofs_hash_lookup(&sbi->dirhash, &dentry->d_name)));
 111         }
 112
 113         /* Abuse this field as a pointer to the directory entry, used to
 114            find the expire list pointers */
 115         dentry->d_time = (unsigned long) ent;
 116
 117         if (!dentry->d_inode) {
 118                 inode = autofs_iget(sb, ent->ino);
 119                 if (IS_ERR(inode)) {
 120                         /* Failed, but leave pending for next time */
 121                         return 1;
 122                 }
 123                 dentry->d_inode = inode;
 124         }
 125
 126         /* If this is a directory that isn't a mount point, bitch at the
 127            daemon and fix it in user space */
 128         if (S_ISDIR(dentry->d_inode->i_mode) && !d_mountpoint(dentry)) {
 129                 return !autofs_wait(sbi, &dentry->d_name);
 130         }
 131
 132         /* We don't update the usages for the autofs daemon itself, this
 133            is necessary for recursive autofs mounts */
 134         if (!autofs_oz_mode(sbi)) {
 135                 autofs_update_usage(&sbi->dirhash,ent);
 136         }
 137
 138         dentry->d_flags &= ~DCACHE_AUTOFS_PENDING;
 139         return 1;
 140 }
 141
 142
 143 /*
 144  * Revalidate is called on every cache lookup.  Some of those
 145  * cache lookups may actually happen while the dentry is not
 146  * yet completely filled in, and revalidate has to delay such
 147  * lookups..
 148  */
 149 static int autofs_revalidate(struct dentry * dentry, struct nameidata *nd)
 150 {
 151         struct inode * dir;
 152         struct autofs_sb_info *sbi;
 153         struct autofs_dir_ent *ent;
 154         int res;
 155
 156         lock_kernel();
 157         dir = dentry->d_parent->d_inode;
 158         sbi = autofs_sbi(dir->i_sb);
 159
 160         /* Pending dentry */
 161         if (dentry->d_flags & DCACHE_AUTOFS_PENDING) {
 162                 if (autofs_oz_mode(sbi))
 163                         res = 1;
 164                 else
 165                         res = try_to_fill_dentry(dentry, dir->i_sb, sbi);
 166                 unlock_kernel();
 167                 return res;
 168         }
 169
 170         /* Negative dentry.. invalidate if "old" */
 171         if (!dentry->d_inode) {
 172                 unlock_kernel();
 173                 return (dentry->d_time - jiffies <= AUTOFS_NEGATIVE_TIMEOUT);
 174         }
 175
 176         /* Check for a non-mountpoint directory */
 177         if (S_ISDIR(dentry->d_inode->i_mode) && !d_mountpoint(dentry)) {
 178                 if (autofs_oz_mode(sbi))
 179                         res = 1;
 180                 else
 181                         res = try_to_fill_dentry(dentry, dir->i_sb, sbi);
 182                 unlock_kernel();
 183                 return res;
 184         }
 185
 186         /* Update the usage list */
 187         if (!autofs_oz_mode(sbi)) {
 188                 ent = (struct autofs_dir_ent *) dentry->d_time;
 189                 if (ent)
 190                         autofs_update_usage(&sbi->dirhash,ent);
 191         }
 192         unlock_kernel();
 193         return 1;
 194 }
 195
 196 static const struct dentry_operations autofs_dentry_operations = {
 197         .d_revalidate   = autofs_revalidate,
 198 };
 199
 200 static struct dentry *autofs_root_lookup(struct inode *dir, struct dentry *dentry, struct nameidata *nd)
 201 {
 202         struct autofs_sb_info *sbi;
 203         int oz_mode;
 204
 205         DPRINTK(("autofs_root_lookup: name = "));
 206         lock_kernel();
 207         autofs_say(dentry->d_name.name,dentry->d_name.len);
 208
 209         if (dentry->d_name.len > NAME_MAX) {
 210                 unlock_kernel();
 211                 return ERR_PTR(-ENAMETOOLONG);/* File name too long to exist */
 212         }
 213
 214         sbi = autofs_sbi(dir->i_sb);
 215
 216         oz_mode = autofs_oz_mode(sbi);
 217         DPRINTK(("autofs_lookup: pid = %u, pgrp = %u, catatonic = %d, "
 218                                 "oz_mode = %d\n", task_pid_nr(current),
 219                                 task_pgrp_nr(current), sbi->catatonic,
 220                                 oz_mode));
 221
 222         /*
 223          * Mark the dentry incomplete, but add it. This is needed so
 224          * that the VFS layer knows about the dentry, and we can count
 225          * on catching any lookups through the revalidate.
 226          *
 227          * Let all the hard work be done by the revalidate function that
 228          * needs to be able to do this anyway..
 229          *
 230          * We need to do this before we release the directory semaphore.
 231          */
 232         dentry->d_op = &autofs_dentry_operations;
 233         dentry->d_flags |= DCACHE_AUTOFS_PENDING;
 234         d_add(dentry, NULL);
 235
 236         mutex_unlock(&dir->i_mutex);
 237         autofs_revalidate(dentry, nd);
 238         mutex_lock(&dir->i_mutex);
 239
 240         /*
 241          * If we are still pending, check if we had to handle
 242          * a signal. If so we can force a restart..
 243          */
 244         if (dentry->d_flags & DCACHE_AUTOFS_PENDING) {
 245                 /* See if we were interrupted */
 246                 if (signal_pending(current)) {
 247                         sigset_t *sigset = &current->pending.signal;
 248                         if (sigismember (sigset, SIGKILL) ||
 249                             sigismember (sigset, SIGQUIT) ||
 250                             sigismember (sigset, SIGINT)) {
 251                                 unlock_kernel();
 252                                 return ERR_PTR(-ERESTARTNOINTR);
 253                         }
 254                 }
 255         }
 256         unlock_kernel();
 257
 258         /*
 259          * If this dentry is unhashed, then we shouldn't honour this
 260          * lookup even if the dentry is positive.  Returning ENOENT here
 261          * doesn't do the right thing for all system calls, but it should
 262          * be OK for the operations we permit from an autofs.
 263          */
 264         if (dentry->d_inode && d_unhashed(dentry))
 265                 return ERR_PTR(-ENOENT);
 266
 267         return NULL;
 268 }
 269
 270 static int autofs_root_symlink(struct inode *dir, struct dentry *dentry, const char *symname)
 271 {
 272         struct autofs_sb_info *sbi = autofs_sbi(dir->i_sb);
 273         struct autofs_dirhash *dh = &sbi->dirhash;
 274         struct autofs_dir_ent *ent;
 275         unsigned int n;
 276         int slsize;
 277         struct autofs_symlink *sl;
 278         struct inode *inode;
 279
 280         DPRINTK(("autofs_root_symlink: %s <- ", symname));
 281         autofs_say(dentry->d_name.name,dentry->d_name.len);
 282
 283         lock_kernel();
 284         if (!autofs_oz_mode(sbi)) {
 285                 unlock_kernel();
 286                 return -EACCES;
 287         }
 288
 289         if (autofs_hash_lookup(dh, &dentry->d_name)) {
 290                 unlock_kernel();
 291                 return -EEXIST;
 292         }
 293
 294         n = find_first_zero_bit(sbi->symlink_bitmap,AUTOFS_MAX_SYMLINKS);
 295         if (n >= AUTOFS_MAX_SYMLINKS) {
 296                 unlock_kernel();
 297                 return -ENOSPC;
 298         }
 299
 300         set_bit(n,sbi->symlink_bitmap);
 301         sl = &sbi->symlink[n];
 302         sl->len = strlen(symname);
 303         sl->data = kmalloc(slsize = sl->len+1, GFP_KERNEL);
 304         if (!sl->data) {
 305                 clear_bit(n,sbi->symlink_bitmap);
 306                 unlock_kernel();
 307                 return -ENOSPC;
 308         }
 309
 310         ent = kmalloc(sizeof(struct autofs_dir_ent), GFP_KERNEL);
 311         if (!ent) {
 312                 kfree(sl->data);
 313                 clear_bit(n,sbi->symlink_bitmap);
 314                 unlock_kernel();
 315                 return -ENOSPC;
 316         }
 317
 318         ent->name = kmalloc(dentry->d_name.len+1, GFP_KERNEL);
 319         if (!ent->name) {
 320                 kfree(sl->data);
 321                 kfree(ent);
 322                 clear_bit(n,sbi->symlink_bitmap);
 323                 unlock_kernel();
 324                 return -ENOSPC;
 325         }
 326
 327         memcpy(sl->data,symname,slsize);
 328         sl->mtime = get_seconds();
 329
 330         ent->ino = AUTOFS_FIRST_SYMLINK + n;
 331         ent->hash = dentry->d_name.hash;
 332         memcpy(ent->name, dentry->d_name.name, 1+(ent->len = dentry->d_name.len));
 333         ent->dentry = NULL;     /* We don't keep the dentry for symlinks */
 334
 335         autofs_hash_insert(dh,ent);
 336
 337         inode = autofs_iget(dir->i_sb, ent->ino);
 338         if (IS_ERR(inode))
 339                 return PTR_ERR(inode);
 340
 341         d_instantiate(dentry, inode);
 342         unlock_kernel();
 343         return 0;
 344 }
 345
 346 /*
 347  * NOTE!
 348  *
 349  * Normal filesystems would do a "d_delete()" to tell the VFS dcache
 350  * that the file no longer exists. However, doing that means that the
 351  * VFS layer can turn the dentry into a negative dentry, which we
 352  * obviously do not want (we're dropping the entry not because it
 353  * doesn't exist, but because it has timed out).
 354  *
 355  * Also see autofs_root_rmdir()..
 356  */
 357 static int autofs_root_unlink(struct inode *dir, struct dentry *dentry)
 358 {
 359         struct autofs_sb_info *sbi = autofs_sbi(dir->i_sb);
 360         struct autofs_dirhash *dh = &sbi->dirhash;
 361         struct autofs_dir_ent *ent;
 362         unsigned int n;
 363
 364         /* This allows root to remove symlinks */
 365         lock_kernel();
 366         if (!autofs_oz_mode(sbi) && !capable(CAP_SYS_ADMIN)) {
 367                 unlock_kernel();
 368                 return -EACCES;
 369         }
 370
 371         ent = autofs_hash_lookup(dh, &dentry->d_name);
 372         if (!ent) {
 373                 unlock_kernel();
 374                 return -ENOENT;
 375         }
 376
 377         n = ent->ino - AUTOFS_FIRST_SYMLINK;
 378         if (n >= AUTOFS_MAX_SYMLINKS) {
 379                 unlock_kernel();
 380                 return -EISDIR; /* It's a directory, dummy */
 381         }
 382         if (!test_bit(n,sbi->symlink_bitmap)) {
 383                 unlock_kernel();
 384                 return -EINVAL; /* Nonexistent symlink?  Shouldn't happen */
 385         }
 386
 387         dentry->d_time = (unsigned long)(struct autofs_dirhash *)NULL;
 388         autofs_hash_delete(ent);
 389         clear_bit(n,sbi->symlink_bitmap);
 390         kfree(sbi->symlink[n].data);
 391         d_drop(dentry);
 392
 393         unlock_kernel();
 394         return 0;
 395 }
 396
 397 static int autofs_root_rmdir(struct inode *dir, struct dentry *dentry)
 398 {
 399         struct autofs_sb_info *sbi = autofs_sbi(dir->i_sb);
 400         struct autofs_dirhash *dh = &sbi->dirhash;
 401         struct autofs_dir_ent *ent;
 402
 403         lock_kernel();
 404         if (!autofs_oz_mode(sbi)) {
 405                 unlock_kernel();
 406                 return -EACCES;
 407         }
 408
 409         ent = autofs_hash_lookup(dh, &dentry->d_name);
 410         if (!ent) {
 411                 unlock_kernel();
 412                 return -ENOENT;
 413         }
 414
 415         if ((unsigned int)ent->ino < AUTOFS_FIRST_DIR_INO) {
 416                 unlock_kernel();
 417                 return -ENOTDIR; /* Not a directory */
 418         }
 419
 420         if (ent->dentry != dentry) {
 421                 printk("autofs_rmdir: odentry != dentry for entry %s\n", dentry->d_name.name);
 422         }
 423
 424         dentry->d_time = (unsigned long)(struct autofs_dir_ent *)NULL;
 425         autofs_hash_delete(ent);
 426         drop_nlink(dir);
 427         d_drop(dentry);
 428         unlock_kernel();
 429
 430         return 0;
 431 }
 432
 433 static int autofs_root_mkdir(struct inode *dir, struct dentry *dentry, int mode)
 434 {
 435         struct autofs_sb_info *sbi = autofs_sbi(dir->i_sb);
 436         struct autofs_dirhash *dh = &sbi->dirhash;
 437         struct autofs_dir_ent *ent;
 438         struct inode *inode;
 439         ino_t ino;
 440
 441         lock_kernel();
 442         if (!autofs_oz_mode(sbi)) {
 443                 unlock_kernel();
 444                 return -EACCES;
 445         }
 446
 447         ent = autofs_hash_lookup(dh, &dentry->d_name);
 448         if (ent) {
 449                 unlock_kernel();
 450                 return -EEXIST;
 451         }
 452
 453         if (sbi->next_dir_ino < AUTOFS_FIRST_DIR_INO) {
 454                 printk("autofs: Out of inode numbers -- what the heck did you do??\n");
 455                 unlock_kernel();
 456                 return -ENOSPC;
 457         }
 458         ino = sbi->next_dir_ino++;
 459
 460         ent = kmalloc(sizeof(struct autofs_dir_ent), GFP_KERNEL);
 461         if (!ent) {
 462                 unlock_kernel();
 463                 return -ENOSPC;
 464         }
 465
 466         ent->name = kmalloc(dentry->d_name.len+1, GFP_KERNEL);
 467         if (!ent->name) {
 468                 kfree(ent);
 469                 unlock_kernel();
 470                 return -ENOSPC;
 471         }
 472
 473         ent->hash = dentry->d_name.hash;
 474         memcpy(ent->name, dentry->d_name.name, 1+(ent->len = dentry->d_name.len));
 475         ent->ino = ino;
 476         ent->dentry = dentry;
 477         autofs_hash_insert(dh,ent);
 478
 479         inc_nlink(dir);
 480
 481         inode = autofs_iget(dir->i_sb, ino);
 482         if (IS_ERR(inode)) {
 483                 drop_nlink(dir);
 484                 return PTR_ERR(inode);
 485         }
 486
 487         d_instantiate(dentry, inode);
 488         unlock_kernel();
 489
 490         return 0;
 491 }
 492
 493 /* Get/set timeout ioctl() operation */
 494 static inline int autofs_get_set_timeout(struct autofs_sb_info *sbi,
 495                                          unsigned long __user *p)
 496 {
 497         unsigned long ntimeout;
 498
 499         if (get_user(ntimeout, p) ||
 500             put_user(sbi->exp_timeout / HZ, p))
 501                 return -EFAULT;
 502
 503         if (ntimeout > ULONG_MAX/HZ)
 504                 sbi->exp_timeout = 0;
 505         else
 506                 sbi->exp_timeout = ntimeout * HZ;
 507
 508         return 0;
 509 }
 510
 511 /* Return protocol version */
 512 static inline int autofs_get_protover(int __user *p)
 513 {
 514         return put_user(AUTOFS_PROTO_VERSION, p);
 515 }
 516
 517 /* Perform an expiry operation */
 518 static inline int autofs_expire_run(struct super_block *sb,
 519                                     struct autofs_sb_info *sbi,
 520                                     struct vfsmount *mnt,
 521                                     struct autofs_packet_expire __user *pkt_p)
 522 {
 523         struct autofs_dir_ent *ent;
 524         struct autofs_packet_expire pkt;
 525
 526         memset(&pkt,0,sizeof pkt);
 527
 528         pkt.hdr.proto_version = AUTOFS_PROTO_VERSION;
 529         pkt.hdr.type = autofs_ptype_expire;
 530
 531         if (!sbi->exp_timeout || !(ent = autofs_expire(sb,sbi,mnt)))
 532                 return -EAGAIN;
 533
 534         pkt.len = ent->len;
 535         memcpy(pkt.name, ent->name, pkt.len);
 536         pkt.name[pkt.len] = '\0';
 537
 538         if (copy_to_user(pkt_p, &pkt, sizeof(struct autofs_packet_expire)))
 539                 return -EFAULT;
 540
 541         return 0;
 542 }
 543
 544 /*
 545  * ioctl()'s on the root directory is the chief method for the daemon to
 546  * generate kernel reactions
 547  */
 548 static int autofs_root_ioctl(struct inode *inode, struct file *filp,
 549                              unsigned int cmd, unsigned long arg)
 550 {
 551         struct autofs_sb_info *sbi = autofs_sbi(inode->i_sb);
 552         void __user *argp = (void __user *)arg;
 553
 554         DPRINTK(("autofs_ioctl: cmd = 0x%08x, arg = 0x%08lx, sbi = %p, pgrp = %u\n",cmd,arg,sbi,task_pgrp_nr(current)));
 555
 556         if (_IOC_TYPE(cmd) != _IOC_TYPE(AUTOFS_IOC_FIRST) ||
 557              _IOC_NR(cmd) - _IOC_NR(AUTOFS_IOC_FIRST) >= AUTOFS_IOC_COUNT)
 558                 return -ENOTTY;
 559
 560         if (!autofs_oz_mode(sbi) && !capable(CAP_SYS_ADMIN))
 561                 return -EPERM;
 562
 563         switch(cmd) {
 564         case AUTOFS_IOC_READY:  /* Wait queue: go ahead and retry */
 565                 return autofs_wait_release(sbi,(autofs_wqt_t)arg,0);
 566         case AUTOFS_IOC_FAIL:   /* Wait queue: fail with ENOENT */
 567                 return autofs_wait_release(sbi,(autofs_wqt_t)arg,-ENOENT);
 568         case AUTOFS_IOC_CATATONIC: /* Enter catatonic mode (daemon shutdown) */
 569                 autofs_catatonic_mode(sbi);
 570                 return 0;
 571         case AUTOFS_IOC_PROTOVER: /* Get protocol version */
 572                 return autofs_get_protover(argp);
 573         case AUTOFS_IOC_SETTIMEOUT:
 574                 return autofs_get_set_timeout(sbi, argp);
 575         case AUTOFS_IOC_EXPIRE:
 576                 return autofs_expire_run(inode->i_sb, sbi, filp->f_path.mnt,
 577                                          argp);
 578         default:
 579                 return -ENOSYS;
 580         }
 581 }