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