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