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         .llseek         = generic_file_llseek,
  32         .read           = generic_read_dir,
  33         .readdir        = autofs_root_readdir,
  34         .ioctl          = autofs_root_ioctl,
  35 };
  36
  37 const struct inode_operations autofs_root_inode_operations = {
  38         .lookup         = autofs_root_lookup,
  39         .unlink         = autofs_root_unlink,
  40         .symlink        = autofs_root_symlink,
  41         .mkdir          = autofs_root_mkdir,
  42         .rmdir          = autofs_root_rmdir,
  43 };
  44
  45 static int autofs_root_readdir(struct file *filp, void *dirent, filldir_t filldir)
  46 {
  47         struct autofs_dir_ent *ent = NULL;
  48         struct autofs_dirhash *dirhash;
  49         struct autofs_sb_info *sbi;
  50         struct inode * inode = filp->f_path.dentry->d_inode;
  51         off_t onr, nr;
  52
  53         lock_kernel();
  54
  55         sbi = autofs_sbi(inode->i_sb);
  56         dirhash = &sbi->dirhash;
  57         nr = filp->f_pos;
  58
  59         switch(nr)
  60         {
  61         case 0:
  62                 if (filldir(dirent, ".", 1, nr, inode->i_ino, DT_DIR) < 0)
  63                         goto out;
  64                 filp->f_pos = ++nr;
  65                 /* fall through */
  66         case 1:
  67                 if (filldir(dirent, "..", 2, nr, inode->i_ino, DT_DIR) < 0)
  68                         goto out;
  69                 filp->f_pos = ++nr;
  70                 /* fall through */
  71         default:
  72                 while (onr = nr, ent = autofs_hash_enum(dirhash,&nr,ent)) {
  73                         if (!ent->dentry || d_mountpoint(ent->dentry)) {
  74                                 if (filldir(dirent,ent->name,ent->len,onr,ent->ino,DT_UNKNOWN) < 0)
  75                                         goto out;
  76                                 filp->f_pos = nr;
  77                         }
  78                 }
  79                 break;
  80         }
  81
  82 out:
  83         unlock_kernel();
  84         return 0;
  85 }
  86
  87 static int try_to_fill_dentry(struct dentry *dentry, struct super_block *sb, struct autofs_sb_info *sbi)
  88 {
  89         struct inode * inode;
  90         struct autofs_dir_ent *ent;
  91         int status = 0;
  92
  93         if (!(ent = autofs_hash_lookup(&sbi->dirhash, &dentry->d_name))) {
  94                 do {
  95                         if (status && dentry->d_inode) {
  96                                 if (status != -ENOENT)
  97                                         printk("autofs warning: lookup failure on positive dentry, status = %d, name = %s\n", status, dentry->d_name.name);
  98                                 return 0; /* Try to get the kernel to invalidate this dentry */
  99                         }
 100
 101                         /* Turn this into a real negative dentry? */
 102                         if (status == -ENOENT) {
 103                                 dentry->d_time = jiffies + AUTOFS_NEGATIVE_TIMEOUT;
 104                                 dentry->d_flags &= ~DCACHE_AUTOFS_PENDING;
 105                                 return 1;
 106                         } else if (status) {
 107                                 /* Return a negative dentry, but leave it "pending" */
 108                                 return 1;
 109                         }
 110                         status = autofs_wait(sbi, &dentry->d_name);
 111                 } while (!(ent = autofs_hash_lookup(&sbi->dirhash, &dentry->d_name)));
 112         }
 113
 114         /* Abuse this field as a pointer to the directory entry, used to
 115            find the expire list pointers */
 116         dentry->d_time = (unsigned long) ent;
 117
 118         if (!dentry->d_inode) {
 119                 inode = autofs_iget(sb, ent->ino);
 120                 if (IS_ERR(inode)) {
 121                         /* Failed, but leave pending for next time */
 122                         return 1;
 123                 }
 124                 dentry->d_inode = inode;
 125         }
 126
 127         /* If this is a directory that isn't a mount point, bitch at the
 128            daemon and fix it in user space */
 129         if (S_ISDIR(dentry->d_inode->i_mode) && !d_mountpoint(dentry)) {
 130                 return !autofs_wait(sbi, &dentry->d_name);
 131         }
 132
 133         /* We don't update the usages for the autofs daemon itself, this
 134            is necessary for recursive autofs mounts */
 135         if (!autofs_oz_mode(sbi)) {
 136                 autofs_update_usage(&sbi->dirhash,ent);
 137         }
 138
 139         dentry->d_flags &= ~DCACHE_AUTOFS_PENDING;
 140         return 1;
 141 }
 142
 143
 144 /*
 145  * Revalidate is called on every cache lookup.  Some of those
 146  * cache lookups may actually happen while the dentry is not
 147  * yet completely filled in, and revalidate has to delay such
 148  * lookups..
 149  */
 150 static int autofs_revalidate(struct dentry * dentry, struct nameidata *nd)
 151 {
 152         struct inode * dir;
 153         struct autofs_sb_info *sbi;
 154         struct autofs_dir_ent *ent;
 155         int res;
 156
 157         lock_kernel();
 158         dir = dentry->d_parent->d_inode;
 159         sbi = autofs_sbi(dir->i_sb);
 160
 161         /* Pending dentry */
 162         if (dentry->d_flags & DCACHE_AUTOFS_PENDING) {
 163                 if (autofs_oz_mode(sbi))
 164                         res = 1;
 165                 else
 166                         res = try_to_fill_dentry(dentry, dir->i_sb, sbi);
 167                 unlock_kernel();
 168                 return res;
 169         }
 170
 171         /* Negative dentry.. invalidate if "old" */
 172         if (!dentry->d_inode) {
 173                 unlock_kernel();
 174                 return (dentry->d_time - jiffies <= AUTOFS_NEGATIVE_TIMEOUT);
 175         }
 176
 177         /* Check for a non-mountpoint directory */
 178         if (S_ISDIR(dentry->d_inode->i_mode) && !d_mountpoint(dentry)) {
 179                 if (autofs_oz_mode(sbi))
 180                         res = 1;
 181                 else
 182                         res = try_to_fill_dentry(dentry, dir->i_sb, sbi);
 183                 unlock_kernel();
 184                 return res;
 185         }
 186
 187         /* Update the usage list */
 188         if (!autofs_oz_mode(sbi)) {
 189                 ent = (struct autofs_dir_ent *) dentry->d_time;
 190                 if (ent)
 191                         autofs_update_usage(&sbi->dirhash,ent);
 192         }
 193         unlock_kernel();
 194         return 1;
 195 }
 196
 197 static const struct dentry_operations autofs_dentry_operations = {
 198         .d_revalidate   = autofs_revalidate,
 199 };
 200
 201 static struct dentry *autofs_root_lookup(struct inode *dir, struct dentry *dentry, struct nameidata *nd)
 202 {
 203         struct autofs_sb_info *sbi;
 204         int oz_mode;
 205
 206         DPRINTK(("autofs_root_lookup: name = "));
 207         lock_kernel();
 208         autofs_say(dentry->d_name.name,dentry->d_name.len);
 209
 210         if (dentry->d_name.len > NAME_MAX) {
 211                 unlock_kernel();
 212                 return ERR_PTR(-ENAMETOOLONG);/* File name too long to exist */
 213         }
 214
 215         sbi = autofs_sbi(dir->i_sb);
 216
 217         oz_mode = autofs_oz_mode(sbi);
 218         DPRINTK(("autofs_lookup: pid = %u, pgrp = %u, catatonic = %d, "
 219                                 "oz_mode = %d\n", task_pid_nr(current),
 220                                 task_pgrp_nr(current), sbi->catatonic,
 221                                 oz_mode));
 222
 223         /*
 224          * Mark the dentry incomplete, but add it. This is needed so
 225          * that the VFS layer knows about the dentry, and we can count
 226          * on catching any lookups through the revalidate.
 227          *
 228          * Let all the hard work be done by the revalidate function that
 229          * needs to be able to do this anyway..
 230          *
 231          * We need to do this before we release the directory semaphore.
 232          */
 233         dentry->d_op = &autofs_dentry_operations;
 234         dentry->d_flags |= DCACHE_AUTOFS_PENDING;
 235         d_add(dentry, NULL);
 236
 237         mutex_unlock(&dir->i_mutex);
 238         autofs_revalidate(dentry, nd);
 239         mutex_lock(&dir->i_mutex);
 240
 241         /*
 242          * If we are still pending, check if we had to handle
 243          * a signal. If so we can force a restart..
 244          */
 245         if (dentry->d_flags & DCACHE_AUTOFS_PENDING) {
 246                 /* See if we were interrupted */
 247                 if (signal_pending(current)) {
 248                         sigset_t *sigset = &current->pending.signal;
 249                         if (sigismember (sigset, SIGKILL) ||
 250                             sigismember (sigset, SIGQUIT) ||
 251                             sigismember (sigset, SIGINT)) {
 252                                 unlock_kernel();
 253                                 return ERR_PTR(-ERESTARTNOINTR);
 254                         }
 255                 }
 256         }
 257         unlock_kernel();
 258
 259         /*
 260          * If this dentry is unhashed, then we shouldn't honour this
 261          * lookup even if the dentry is positive.  Returning ENOENT here
 262          * doesn't do the right thing for all system calls, but it should
 263          * be OK for the operations we permit from an autofs.
 264          */
 265         if (dentry->d_inode && d_unhashed(dentry))
 266                 return ERR_PTR(-ENOENT);
 267
 268         return NULL;
 269 }
 270
 271 static int autofs_root_symlink(struct inode *dir, struct dentry *dentry, const char *symname)
 272 {
 273         struct autofs_sb_info *sbi = autofs_sbi(dir->i_sb);
 274         struct autofs_dirhash *dh = &sbi->dirhash;
 275         struct autofs_dir_ent *ent;
 276         unsigned int n;
 277         int slsize;
 278         struct autofs_symlink *sl;
 279         struct inode *inode;
 280
 281         DPRINTK(("autofs_root_symlink: %s <- ", symname));
 282         autofs_say(dentry->d_name.name,dentry->d_name.len);
 283
 284         lock_kernel();
 285         if (!autofs_oz_mode(sbi)) {
 286                 unlock_kernel();
 287                 return -EACCES;
 288         }
 289
 290         if (autofs_hash_lookup(dh, &dentry->d_name)) {
 291                 unlock_kernel();
 292                 return -EEXIST;
 293         }
 294
 295         n = find_first_zero_bit(sbi->symlink_bitmap,AUTOFS_MAX_SYMLINKS);
 296         if (n >= AUTOFS_MAX_SYMLINKS) {
 297                 unlock_kernel();
 298                 return -ENOSPC;
 299         }
 300
 301         set_bit(n,sbi->symlink_bitmap);
 302         sl = &sbi->symlink[n];
 303         sl->len = strlen(symname);
 304         sl->data = kmalloc(slsize = sl->len+1, GFP_KERNEL);
 305         if (!sl->data) {
 306                 clear_bit(n,sbi->symlink_bitmap);
 307                 unlock_kernel();
 308                 return -ENOSPC;
 309         }
 310
 311         ent = kmalloc(sizeof(struct autofs_dir_ent), GFP_KERNEL);
 312         if (!ent) {
 313                 kfree(sl->data);
 314                 clear_bit(n,sbi->symlink_bitmap);
 315                 unlock_kernel();
 316                 return -ENOSPC;
 317         }
 318
 319         ent->name = kmalloc(dentry->d_name.len+1, GFP_KERNEL);
 320         if (!ent->name) {
 321                 kfree(sl->data);
 322                 kfree(ent);
 323                 clear_bit(n,sbi->symlink_bitmap);
 324                 unlock_kernel();
 325                 return -ENOSPC;
 326         }
 327
 328         memcpy(sl->data,symname,slsize);
 329         sl->mtime = get_seconds();
 330
 331         ent->ino = AUTOFS_FIRST_SYMLINK + n;
 332         ent->hash = dentry->d_name.hash;
 333         memcpy(ent->name, dentry->d_name.name, 1+(ent->len = dentry->d_name.len));
 334         ent->dentry = NULL;     /* We don't keep the dentry for symlinks */
 335
 336         autofs_hash_insert(dh,ent);
 337
 338         inode = autofs_iget(dir->i_sb, ent->ino);
 339         if (IS_ERR(inode))
 340                 return PTR_ERR(inode);
 341
 342         d_instantiate(dentry, inode);
 343         unlock_kernel();
 344         return 0;
 345 }
 346
 347 /*
 348  * NOTE!
 349  *
 350  * Normal filesystems would do a "d_delete()" to tell the VFS dcache
 351  * that the file no longer exists. However, doing that means that the
 352  * VFS layer can turn the dentry into a negative dentry, which we
 353  * obviously do not want (we're dropping the entry not because it
 354  * doesn't exist, but because it has timed out).
 355  *
 356  * Also see autofs_root_rmdir()..
 357  */
 358 static int autofs_root_unlink(struct inode *dir, struct dentry *dentry)
 359 {
 360         struct autofs_sb_info *sbi = autofs_sbi(dir->i_sb);
 361         struct autofs_dirhash *dh = &sbi->dirhash;
 362         struct autofs_dir_ent *ent;
 363         unsigned int n;
 364
 365         /* This allows root to remove symlinks */
 366         lock_kernel();
 367         if (!autofs_oz_mode(sbi) && !capable(CAP_SYS_ADMIN)) {
 368                 unlock_kernel();
 369                 return -EACCES;
 370         }
 371
 372         ent = autofs_hash_lookup(dh, &dentry->d_name);
 373         if (!ent) {
 374                 unlock_kernel();
 375                 return -ENOENT;
 376         }
 377
 378         n = ent->ino - AUTOFS_FIRST_SYMLINK;
 379         if (n >= AUTOFS_MAX_SYMLINKS) {
 380                 unlock_kernel();
 381                 return -EISDIR; /* It's a directory, dummy */
 382         }
 383         if (!test_bit(n,sbi->symlink_bitmap)) {
 384                 unlock_kernel();
 385                 return -EINVAL; /* Nonexistent symlink?  Shouldn't happen */
 386         }
 387
 388         dentry->d_time = (unsigned long)(struct autofs_dirhash *)NULL;
 389         autofs_hash_delete(ent);
 390         clear_bit(n,sbi->symlink_bitmap);
 391         kfree(sbi->symlink[n].data);
 392         d_drop(dentry);
 393
 394         unlock_kernel();
 395         return 0;
 396 }
 397
 398 static int autofs_root_rmdir(struct inode *dir, struct dentry *dentry)
 399 {
 400         struct autofs_sb_info *sbi = autofs_sbi(dir->i_sb);
 401         struct autofs_dirhash *dh = &sbi->dirhash;
 402         struct autofs_dir_ent *ent;
 403
 404         lock_kernel();
 405         if (!autofs_oz_mode(sbi)) {
 406                 unlock_kernel();
 407                 return -EACCES;
 408         }
 409
 410         ent = autofs_hash_lookup(dh, &dentry->d_name);
 411         if (!ent) {
 412                 unlock_kernel();
 413                 return -ENOENT;
 414         }
 415
 416         if ((unsigned int)ent->ino < AUTOFS_FIRST_DIR_INO) {
 417                 unlock_kernel();
 418                 return -ENOTDIR; /* Not a directory */
 419         }
 420
 421         if (ent->dentry != dentry) {
 422                 printk("autofs_rmdir: odentry != dentry for entry %s\n", dentry->d_name.name);
 423         }
 424
 425         dentry->d_time = (unsigned long)(struct autofs_dir_ent *)NULL;
 426         autofs_hash_delete(ent);
 427         drop_nlink(dir);
 428         d_drop(dentry);
 429         unlock_kernel();
 430
 431         return 0;
 432 }
 433
 434 static int autofs_root_mkdir(struct inode *dir, struct dentry *dentry, int mode)
 435 {
 436         struct autofs_sb_info *sbi = autofs_sbi(dir->i_sb);
 437         struct autofs_dirhash *dh = &sbi->dirhash;
 438         struct autofs_dir_ent *ent;
 439         struct inode *inode;
 440         ino_t ino;
 441
 442         lock_kernel();
 443         if (!autofs_oz_mode(sbi)) {
 444                 unlock_kernel();
 445                 return -EACCES;
 446         }
 447
 448         ent = autofs_hash_lookup(dh, &dentry->d_name);
 449         if (ent) {
 450                 unlock_kernel();
 451                 return -EEXIST;
 452         }
 453
 454         if (sbi->next_dir_ino < AUTOFS_FIRST_DIR_INO) {
 455                 printk("autofs: Out of inode numbers -- what the heck did you do??\n");
 456                 unlock_kernel();
 457                 return -ENOSPC;
 458         }
 459         ino = sbi->next_dir_ino++;
 460
 461         ent = kmalloc(sizeof(struct autofs_dir_ent), GFP_KERNEL);
 462         if (!ent) {
 463                 unlock_kernel();
 464                 return -ENOSPC;
 465         }
 466
 467         ent->name = kmalloc(dentry->d_name.len+1, GFP_KERNEL);
 468         if (!ent->name) {
 469                 kfree(ent);
 470                 unlock_kernel();
 471                 return -ENOSPC;
 472         }
 473
 474         ent->hash = dentry->d_name.hash;
 475         memcpy(ent->name, dentry->d_name.name, 1+(ent->len = dentry->d_name.len));
 476         ent->ino = ino;
 477         ent->dentry = dentry;
 478         autofs_hash_insert(dh,ent);
 479
 480         inc_nlink(dir);
 481
 482         inode = autofs_iget(dir->i_sb, ino);
 483         if (IS_ERR(inode)) {
 484                 drop_nlink(dir);
 485                 return PTR_ERR(inode);
 486         }
 487
 488         d_instantiate(dentry, inode);
 489         unlock_kernel();
 490
 491         return 0;
 492 }
 493
 494 /* Get/set timeout ioctl() operation */
 495 static inline int autofs_get_set_timeout(struct autofs_sb_info *sbi,
 496                                          unsigned long __user *p)
 497 {
 498         unsigned long ntimeout;
 499
 500         if (get_user(ntimeout, p) ||
 501             put_user(sbi->exp_timeout / HZ, p))
 502                 return -EFAULT;
 503
 504         if (ntimeout > ULONG_MAX/HZ)
 505                 sbi->exp_timeout = 0;
 506         else
 507                 sbi->exp_timeout = ntimeout * HZ;
 508
 509         return 0;
 510 }
 511
 512 /* Return protocol version */
 513 static inline int autofs_get_protover(int __user *p)
 514 {
 515         return put_user(AUTOFS_PROTO_VERSION, p);
 516 }
 517
 518 /* Perform an expiry operation */
 519 static inline int autofs_expire_run(struct super_block *sb,
 520                                     struct autofs_sb_info *sbi,
 521                                     struct vfsmount *mnt,
 522                                     struct autofs_packet_expire __user *pkt_p)
 523 {
 524         struct autofs_dir_ent *ent;
 525         struct autofs_packet_expire pkt;
 526
 527         memset(&pkt,0,sizeof pkt);
 528
 529         pkt.hdr.proto_version = AUTOFS_PROTO_VERSION;
 530         pkt.hdr.type = autofs_ptype_expire;
 531
 532         if (!sbi->exp_timeout || !(ent = autofs_expire(sb,sbi,mnt)))
 533                 return -EAGAIN;
 534
 535         pkt.len = ent->len;
 536         memcpy(pkt.name, ent->name, pkt.len);
 537         pkt.name[pkt.len] = '\0';
 538
 539         if (copy_to_user(pkt_p, &pkt, sizeof(struct autofs_packet_expire)))
 540                 return -EFAULT;
 541
 542         return 0;
 543 }
 544
 545 /*
 546  * ioctl()'s on the root directory is the chief method for the daemon to
 547  * generate kernel reactions
 548  */
 549 static int autofs_root_ioctl(struct inode *inode, struct file *filp,
 550                              unsigned int cmd, unsigned long arg)
 551 {
 552         struct autofs_sb_info *sbi = autofs_sbi(inode->i_sb);
 553         void __user *argp = (void __user *)arg;
 554
 555         DPRINTK(("autofs_ioctl: cmd = 0x%08x, arg = 0x%08lx, sbi = %p, pgrp = %u\n",cmd,arg,sbi,task_pgrp_nr(current)));
 556
 557         if (_IOC_TYPE(cmd) != _IOC_TYPE(AUTOFS_IOC_FIRST) ||
 558              _IOC_NR(cmd) - _IOC_NR(AUTOFS_IOC_FIRST) >= AUTOFS_IOC_COUNT)
 559                 return -ENOTTY;
 560
 561         if (!autofs_oz_mode(sbi) && !capable(CAP_SYS_ADMIN))
 562                 return -EPERM;
 563
 564         switch(cmd) {
 565         case AUTOFS_IOC_READY:  /* Wait queue: go ahead and retry */
 566                 return autofs_wait_release(sbi,(autofs_wqt_t)arg,0);
 567         case AUTOFS_IOC_FAIL:   /* Wait queue: fail with ENOENT */
 568                 return autofs_wait_release(sbi,(autofs_wqt_t)arg,-ENOENT);
 569         case AUTOFS_IOC_CATATONIC: /* Enter catatonic mode (daemon shutdown) */
 570                 autofs_catatonic_mode(sbi);
 571                 return 0;
 572         case AUTOFS_IOC_PROTOVER: /* Get protocol version */
 573                 return autofs_get_protover(argp);
 574         case AUTOFS_IOC_SETTIMEOUT:
 575                 return autofs_get_set_timeout(sbi, argp);
 576         case AUTOFS_IOC_EXPIRE:
 577                 return autofs_expire_run(inode->i_sb, sbi, filp->f_path.mnt,
 578                                          argp);
 579         default:
 580                 return -ENOSYS;
 581         }
 582 }