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, oz_mode = %d\n",
 217                  current->pid, process_group(current), sbi->catatonic, oz_mode));
 218
 219         /*
 220          * Mark the dentry incomplete, but add it. This is needed so
 221          * that the VFS layer knows about the dentry, and we can count
 222          * on catching any lookups through the revalidate.
 223          *
 224          * Let all the hard work be done by the revalidate function that
 225          * needs to be able to do this anyway..
 226          *
 227          * We need to do this before we release the directory semaphore.
 228          */
 229         dentry->d_op = &autofs_dentry_operations;
 230         dentry->d_flags |= DCACHE_AUTOFS_PENDING;
 231         d_add(dentry, NULL);
 232
 233         mutex_unlock(&dir->i_mutex);
 234         autofs_revalidate(dentry, nd);
 235         mutex_lock(&dir->i_mutex);
 236
 237         /*
 238          * If we are still pending, check if we had to handle
 239          * a signal. If so we can force a restart..
 240          */
 241         if (dentry->d_flags & DCACHE_AUTOFS_PENDING) {
 242                 /* See if we were interrupted */
 243                 if (signal_pending(current)) {
 244                         sigset_t *sigset = &current->pending.signal;
 245                         if (sigismember (sigset, SIGKILL) ||
 246                             sigismember (sigset, SIGQUIT) ||
 247                             sigismember (sigset, SIGINT)) {
 248                                 unlock_kernel();
 249                                 return ERR_PTR(-ERESTARTNOINTR);
 250                         }
 251                 }
 252         }
 253         unlock_kernel();
 254
 255         /*
 256          * If this dentry is unhashed, then we shouldn't honour this
 257          * lookup even if the dentry is positive.  Returning ENOENT here
 258          * doesn't do the right thing for all system calls, but it should
 259          * be OK for the operations we permit from an autofs.
 260          */
 261         if ( dentry->d_inode && d_unhashed(dentry) )
 262                 return ERR_PTR(-ENOENT);
 263
 264         return NULL;
 265 }
 266
 267 static int autofs_root_symlink(struct inode *dir, struct dentry *dentry, const char *symname)
 268 {
 269         struct autofs_sb_info *sbi = autofs_sbi(dir->i_sb);
 270         struct autofs_dirhash *dh = &sbi->dirhash;
 271         struct autofs_dir_ent *ent;
 272         unsigned int n;
 273         int slsize;
 274         struct autofs_symlink *sl;
 275
 276         DPRINTK(("autofs_root_symlink: %s <- ", symname));
 277         autofs_say(dentry->d_name.name,dentry->d_name.len);
 278
 279         lock_kernel();
 280         if ( !autofs_oz_mode(sbi) ) {
 281                 unlock_kernel();
 282                 return -EACCES;
 283         }
 284
 285         if ( autofs_hash_lookup(dh, &dentry->d_name) ) {
 286                 unlock_kernel();
 287                 return -EEXIST;
 288         }
 289
 290         n = find_first_zero_bit(sbi->symlink_bitmap,AUTOFS_MAX_SYMLINKS);
 291         if ( n >= AUTOFS_MAX_SYMLINKS ) {
 292                 unlock_kernel();
 293                 return -ENOSPC;
 294         }
 295
 296         set_bit(n,sbi->symlink_bitmap);
 297         sl = &sbi->symlink[n];
 298         sl->len = strlen(symname);
 299         sl->data = kmalloc(slsize = sl->len+1, GFP_KERNEL);
 300         if ( !sl->data ) {
 301                 clear_bit(n,sbi->symlink_bitmap);
 302                 unlock_kernel();
 303                 return -ENOSPC;
 304         }
 305
 306         ent = kmalloc(sizeof(struct autofs_dir_ent), GFP_KERNEL);
 307         if ( !ent ) {
 308                 kfree(sl->data);
 309                 clear_bit(n,sbi->symlink_bitmap);
 310                 unlock_kernel();
 311                 return -ENOSPC;
 312         }
 313
 314         ent->name = kmalloc(dentry->d_name.len+1, GFP_KERNEL);
 315         if ( !ent->name ) {
 316                 kfree(sl->data);
 317                 kfree(ent);
 318                 clear_bit(n,sbi->symlink_bitmap);
 319                 unlock_kernel();
 320                 return -ENOSPC;
 321         }
 322
 323         memcpy(sl->data,symname,slsize);
 324         sl->mtime = get_seconds();
 325
 326         ent->ino = AUTOFS_FIRST_SYMLINK + n;
 327         ent->hash = dentry->d_name.hash;
 328         memcpy(ent->name, dentry->d_name.name, 1+(ent->len = dentry->d_name.len));
 329         ent->dentry = NULL;     /* We don't keep the dentry for symlinks */
 330
 331         autofs_hash_insert(dh,ent);
 332         d_instantiate(dentry, iget(dir->i_sb,ent->ino));
 333         unlock_kernel();
 334         return 0;
 335 }
 336
 337 /*
 338  * NOTE!
 339  *
 340  * Normal filesystems would do a "d_delete()" to tell the VFS dcache
 341  * that the file no longer exists. However, doing that means that the
 342  * VFS layer can turn the dentry into a negative dentry, which we
 343  * obviously do not want (we're dropping the entry not because it
 344  * doesn't exist, but because it has timed out).
 345  *
 346  * Also see autofs_root_rmdir()..
 347  */
 348 static int autofs_root_unlink(struct inode *dir, struct dentry *dentry)
 349 {
 350         struct autofs_sb_info *sbi = autofs_sbi(dir->i_sb);
 351         struct autofs_dirhash *dh = &sbi->dirhash;
 352         struct autofs_dir_ent *ent;
 353         unsigned int n;
 354
 355         /* This allows root to remove symlinks */
 356         lock_kernel();
 357         if ( !autofs_oz_mode(sbi) && !capable(CAP_SYS_ADMIN) ) {
 358                 unlock_kernel();
 359                 return -EACCES;
 360         }
 361
 362         ent = autofs_hash_lookup(dh, &dentry->d_name);
 363         if ( !ent ) {
 364                 unlock_kernel();
 365                 return -ENOENT;
 366         }
 367
 368         n = ent->ino - AUTOFS_FIRST_SYMLINK;
 369         if ( n >= AUTOFS_MAX_SYMLINKS ) {
 370                 unlock_kernel();
 371                 return -EISDIR; /* It's a directory, dummy */
 372         }
 373         if ( !test_bit(n,sbi->symlink_bitmap) ) {
 374                 unlock_kernel();
 375                 return -EINVAL; /* Nonexistent symlink?  Shouldn't happen */
 376         }
 377
 378         dentry->d_time = (unsigned long)(struct autofs_dirhash *)NULL;
 379         autofs_hash_delete(ent);
 380         clear_bit(n,sbi->symlink_bitmap);
 381         kfree(sbi->symlink[n].data);
 382         d_drop(dentry);
 383
 384         unlock_kernel();
 385         return 0;
 386 }
 387
 388 static int autofs_root_rmdir(struct inode *dir, struct dentry *dentry)
 389 {
 390         struct autofs_sb_info *sbi = autofs_sbi(dir->i_sb);
 391         struct autofs_dirhash *dh = &sbi->dirhash;
 392         struct autofs_dir_ent *ent;
 393
 394         lock_kernel();
 395         if ( !autofs_oz_mode(sbi) ) {
 396                 unlock_kernel();
 397                 return -EACCES;
 398         }
 399
 400         ent = autofs_hash_lookup(dh, &dentry->d_name);
 401         if ( !ent ) {
 402                 unlock_kernel();
 403                 return -ENOENT;
 404         }
 405
 406         if ( (unsigned int)ent->ino < AUTOFS_FIRST_DIR_INO ) {
 407                 unlock_kernel();
 408                 return -ENOTDIR; /* Not a directory */
 409         }
 410
 411         if ( ent->dentry != dentry ) {
 412                 printk("autofs_rmdir: odentry != dentry for entry %s\n", dentry->d_name.name);
 413         }
 414
 415         dentry->d_time = (unsigned long)(struct autofs_dir_ent *)NULL;
 416         autofs_hash_delete(ent);
 417         drop_nlink(dir);
 418         d_drop(dentry);
 419         unlock_kernel();
 420
 421         return 0;
 422 }
 423
 424 static int autofs_root_mkdir(struct inode *dir, struct dentry *dentry, int mode)
 425 {
 426         struct autofs_sb_info *sbi = autofs_sbi(dir->i_sb);
 427         struct autofs_dirhash *dh = &sbi->dirhash;
 428         struct autofs_dir_ent *ent;
 429         ino_t ino;
 430
 431         lock_kernel();
 432         if ( !autofs_oz_mode(sbi) ) {
 433                 unlock_kernel();
 434                 return -EACCES;
 435         }
 436
 437         ent = autofs_hash_lookup(dh, &dentry->d_name);
 438         if ( ent ) {
 439                 unlock_kernel();
 440                 return -EEXIST;
 441         }
 442
 443         if ( sbi->next_dir_ino < AUTOFS_FIRST_DIR_INO ) {
 444                 printk("autofs: Out of inode numbers -- what the heck did you do??\n");
 445                 unlock_kernel();
 446                 return -ENOSPC;
 447         }
 448         ino = sbi->next_dir_ino++;
 449
 450         ent = kmalloc(sizeof(struct autofs_dir_ent), GFP_KERNEL);
 451         if ( !ent ) {
 452                 unlock_kernel();
 453                 return -ENOSPC;
 454         }
 455
 456         ent->name = kmalloc(dentry->d_name.len+1, GFP_KERNEL);
 457         if ( !ent->name ) {
 458                 kfree(ent);
 459                 unlock_kernel();
 460                 return -ENOSPC;
 461         }
 462
 463         ent->hash = dentry->d_name.hash;
 464         memcpy(ent->name, dentry->d_name.name, 1+(ent->len = dentry->d_name.len));
 465         ent->ino = ino;
 466         ent->dentry = dentry;
 467         autofs_hash_insert(dh,ent);
 468
 469         inc_nlink(dir);
 470         d_instantiate(dentry, iget(dir->i_sb,ino));
 471         unlock_kernel();
 472
 473         return 0;
 474 }
 475
 476 /* Get/set timeout ioctl() operation */
 477 static inline int autofs_get_set_timeout(struct autofs_sb_info *sbi,
 478                                          unsigned long __user *p)
 479 {
 480         unsigned long ntimeout;
 481
 482         if (get_user(ntimeout, p) ||
 483             put_user(sbi->exp_timeout / HZ, p))
 484                 return -EFAULT;
 485
 486         if ( ntimeout > ULONG_MAX/HZ )
 487                 sbi->exp_timeout = 0;
 488         else
 489                 sbi->exp_timeout = ntimeout * HZ;
 490
 491         return 0;
 492 }
 493
 494 /* Return protocol version */
 495 static inline int autofs_get_protover(int __user *p)
 496 {
 497         return put_user(AUTOFS_PROTO_VERSION, p);
 498 }
 499
 500 /* Perform an expiry operation */
 501 static inline int autofs_expire_run(struct super_block *sb,
 502                                     struct autofs_sb_info *sbi,
 503                                     struct vfsmount *mnt,
 504                                     struct autofs_packet_expire __user *pkt_p)
 505 {
 506         struct autofs_dir_ent *ent;
 507         struct autofs_packet_expire pkt;
 508
 509         memset(&pkt,0,sizeof pkt);
 510
 511         pkt.hdr.proto_version = AUTOFS_PROTO_VERSION;
 512         pkt.hdr.type = autofs_ptype_expire;
 513
 514         if ( !sbi->exp_timeout ||
 515              !(ent = autofs_expire(sb,sbi,mnt)) )
 516                 return -EAGAIN;
 517
 518         pkt.len = ent->len;
 519         memcpy(pkt.name, ent->name, pkt.len);
 520         pkt.name[pkt.len] = '\0';
 521
 522         if ( copy_to_user(pkt_p, &pkt, sizeof(struct autofs_packet_expire)) )
 523                 return -EFAULT;
 524
 525         return 0;
 526 }
 527
 528 /*
 529  * ioctl()'s on the root directory is the chief method for the daemon to
 530  * generate kernel reactions
 531  */
 532 static int autofs_root_ioctl(struct inode *inode, struct file *filp,
 533                              unsigned int cmd, unsigned long arg)
 534 {
 535         struct autofs_sb_info *sbi = autofs_sbi(inode->i_sb);
 536         void __user *argp = (void __user *)arg;
 537
 538         DPRINTK(("autofs_ioctl: cmd = 0x%08x, arg = 0x%08lx, sbi = %p, pgrp = %u\n",cmd,arg,sbi,process_group(current)));
 539
 540         if ( _IOC_TYPE(cmd) != _IOC_TYPE(AUTOFS_IOC_FIRST) ||
 541              _IOC_NR(cmd) - _IOC_NR(AUTOFS_IOC_FIRST) >= AUTOFS_IOC_COUNT )
 542                 return -ENOTTY;
 543
 544         if ( !autofs_oz_mode(sbi) && !capable(CAP_SYS_ADMIN) )
 545                 return -EPERM;
 546
 547         switch(cmd) {
 548         case AUTOFS_IOC_READY:  /* Wait queue: go ahead and retry */
 549                 return autofs_wait_release(sbi,(autofs_wqt_t)arg,0);
 550         case AUTOFS_IOC_FAIL:   /* Wait queue: fail with ENOENT */
 551                 return autofs_wait_release(sbi,(autofs_wqt_t)arg,-ENOENT);
 552         case AUTOFS_IOC_CATATONIC: /* Enter catatonic mode (daemon shutdown) */
 553                 autofs_catatonic_mode(sbi);
 554                 return 0;
 555         case AUTOFS_IOC_PROTOVER: /* Get protocol version */
 556                 return autofs_get_protover(argp);
 557         case AUTOFS_IOC_SETTIMEOUT:
 558                 return autofs_get_set_timeout(sbi, argp);
 559         case AUTOFS_IOC_EXPIRE:
 560                 return autofs_expire_run(inode->i_sb, sbi, filp->f_path.mnt,
 561                                          argp);
 562         default:
 563                 return -ENOSYS;
 564         }
 565 }