fs/ecryptfs/inode.c

   1 /**
   2  * eCryptfs: Linux filesystem encryption layer
   3  *
   4  * Copyright (C) 1997-2004 Erez Zadok
   5  * Copyright (C) 2001-2004 Stony Brook University
   6  * Copyright (C) 2004-2007 International Business Machines Corp.
   7  *   Author(s): Michael A. Halcrow <mahalcro@us.ibm.com>
   8  *              Michael C. Thompsion <mcthomps@us.ibm.com>
   9  *
  10  * This program is free software; you can redistribute it and/or
  11  * modify it under the terms of the GNU General Public License as
  12  * published by the Free Software Foundation; either version 2 of the
  13  * License, or (at your option) any later version.
  14  *
  15  * This program is distributed in the hope that it will be useful, but
  16  * WITHOUT ANY WARRANTY; without even the implied warranty of
  17  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  18  * General Public License for more details.
  19  *
  20  * You should have received a copy of the GNU General Public License
  21  * along with this program; if not, write to the Free Software
  22  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
  23  * 02111-1307, USA.
  24  */
  25
  26 #include <linux/file.h>
  27 #include <linux/vmalloc.h>
  28 #include <linux/pagemap.h>
  29 #include <linux/dcache.h>
  30 #include <linux/namei.h>
  31 #include <linux/mount.h>
  32 #include <linux/fs_stack.h>
  33 #include <linux/slab.h>
  34 #include <linux/xattr.h>
  35 #include <asm/unaligned.h>
  36 #include "ecryptfs_kernel.h"
  37
  38 static struct dentry *lock_parent(struct dentry *dentry)
  39 {
  40         struct dentry *dir;
  41
  42         dir = dget_parent(dentry);
  43         inode_lock_nested(d_inode(dir), I_MUTEX_PARENT);
  44         return dir;
  45 }
  46
  47 static void unlock_dir(struct dentry *dir)
  48 {
  49         inode_unlock(d_inode(dir));
  50         dput(dir);
  51 }
  52
  53 static int ecryptfs_inode_test(struct inode *inode, void *lower_inode)
  54 {
  55         return ecryptfs_inode_to_lower(inode) == lower_inode;
  56 }
  57
  58 static int ecryptfs_inode_set(struct inode *inode, void *opaque)
  59 {
  60         struct inode *lower_inode = opaque;
  61
  62         ecryptfs_set_inode_lower(inode, lower_inode);
  63         fsstack_copy_attr_all(inode, lower_inode);
  64         /* i_size will be overwritten for encrypted regular files */
  65         fsstack_copy_inode_size(inode, lower_inode);
  66         inode->i_ino = lower_inode->i_ino;
  67         inode->i_version++;
  68         inode->i_mapping->a_ops = &ecryptfs_aops;
  69
  70         if (S_ISLNK(inode->i_mode))
  71                 inode->i_op = &ecryptfs_symlink_iops;
  72         else if (S_ISDIR(inode->i_mode))
  73                 inode->i_op = &ecryptfs_dir_iops;
  74         else
  75                 inode->i_op = &ecryptfs_main_iops;
  76
  77         if (S_ISDIR(inode->i_mode))
  78                 inode->i_fop = &ecryptfs_dir_fops;
  79         else if (special_file(inode->i_mode))
  80                 init_special_inode(inode, inode->i_mode, inode->i_rdev);
  81         else
  82                 inode->i_fop = &ecryptfs_main_fops;
  83
  84         return 0;
  85 }
  86
  87 static struct inode *__ecryptfs_get_inode(struct inode *lower_inode,
  88                                           struct super_block *sb)
  89 {
  90         struct inode *inode;
  91
  92         if (lower_inode->i_sb != ecryptfs_superblock_to_lower(sb))
  93                 return ERR_PTR(-EXDEV);
  94         if (!igrab(lower_inode))
  95                 return ERR_PTR(-ESTALE);
  96         inode = iget5_locked(sb, (unsigned long)lower_inode,
  97                              ecryptfs_inode_test, ecryptfs_inode_set,
  98                              lower_inode);
  99         if (!inode) {
 100                 iput(lower_inode);
 101                 return ERR_PTR(-EACCES);
 102         }
 103         if (!(inode->i_state & I_NEW))
 104                 iput(lower_inode);
 105
 106         return inode;
 107 }
 108
 109 struct inode *ecryptfs_get_inode(struct inode *lower_inode,
 110                                  struct super_block *sb)
 111 {
 112         struct inode *inode = __ecryptfs_get_inode(lower_inode, sb);
 113
 114         if (!IS_ERR(inode) && (inode->i_state & I_NEW))
 115                 unlock_new_inode(inode);
 116
 117         return inode;
 118 }
 119
 120 /**
 121  * ecryptfs_interpose
 122  * @lower_dentry: Existing dentry in the lower filesystem
 123  * @dentry: ecryptfs' dentry
 124  * @sb: ecryptfs's super_block
 125  *
 126  * Interposes upper and lower dentries.
 127  *
 128  * Returns zero on success; non-zero otherwise
 129  */
 130 static int ecryptfs_interpose(struct dentry *lower_dentry,
 131                               struct dentry *dentry, struct super_block *sb)
 132 {
 133         struct inode *inode = ecryptfs_get_inode(d_inode(lower_dentry), sb);
 134
 135         if (IS_ERR(inode))
 136                 return PTR_ERR(inode);
 137         d_instantiate(dentry, inode);
 138
 139         return 0;
 140 }
 141
 142 static int ecryptfs_do_unlink(struct inode *dir, struct dentry *dentry,
 143                               struct inode *inode)
 144 {
 145         struct dentry *lower_dentry = ecryptfs_dentry_to_lower(dentry);
 146         struct inode *lower_dir_inode = ecryptfs_inode_to_lower(dir);
 147         struct dentry *lower_dir_dentry;
 148         int rc;
 149
 150         dget(lower_dentry);
 151         lower_dir_dentry = lock_parent(lower_dentry);
 152         rc = vfs_unlink(lower_dir_inode, lower_dentry, NULL);
 153         if (rc) {
 154                 printk(KERN_ERR "Error in vfs_unlink; rc = [%d]\n", rc);
 155                 goto out_unlock;
 156         }
 157         fsstack_copy_attr_times(dir, lower_dir_inode);
 158         set_nlink(inode, ecryptfs_inode_to_lower(inode)->i_nlink);
 159         inode->i_ctime = dir->i_ctime;
 160         d_drop(dentry);
 161 out_unlock:
 162         unlock_dir(lower_dir_dentry);
 163         dput(lower_dentry);
 164         return rc;
 165 }
 166
 167 /**
 168  * ecryptfs_do_create
 169  * @directory_inode: inode of the new file's dentry's parent in ecryptfs
 170  * @ecryptfs_dentry: New file's dentry in ecryptfs
 171  * @mode: The mode of the new file
 172  *
 173  * Creates the underlying file and the eCryptfs inode which will link to
 174  * it. It will also update the eCryptfs directory inode to mimic the
 175  * stat of the lower directory inode.
 176  *
 177  * Returns the new eCryptfs inode on success; an ERR_PTR on error condition
 178  */
 179 static struct inode *
 180 ecryptfs_do_create(struct inode *directory_inode,
 181                    struct dentry *ecryptfs_dentry, umode_t mode)
 182 {
 183         int rc;
 184         struct dentry *lower_dentry;
 185         struct dentry *lower_dir_dentry;
 186         struct inode *inode;
 187
 188         lower_dentry = ecryptfs_dentry_to_lower(ecryptfs_dentry);
 189         lower_dir_dentry = lock_parent(lower_dentry);
 190         rc = vfs_create(d_inode(lower_dir_dentry), lower_dentry, mode, true);
 191         if (rc) {
 192                 printk(KERN_ERR "%s: Failure to create dentry in lower fs; "
 193                        "rc = [%d]\n", __func__, rc);
 194                 inode = ERR_PTR(rc);
 195                 goto out_lock;
 196         }
 197         inode = __ecryptfs_get_inode(d_inode(lower_dentry),
 198                                      directory_inode->i_sb);
 199         if (IS_ERR(inode)) {
 200                 vfs_unlink(d_inode(lower_dir_dentry), lower_dentry, NULL);
 201                 goto out_lock;
 202         }
 203         fsstack_copy_attr_times(directory_inode, d_inode(lower_dir_dentry));
 204         fsstack_copy_inode_size(directory_inode, d_inode(lower_dir_dentry));
 205 out_lock:
 206         unlock_dir(lower_dir_dentry);
 207         return inode;
 208 }
 209
 210 /**
 211  * ecryptfs_initialize_file
 212  *
 213  * Cause the file to be changed from a basic empty file to an ecryptfs
 214  * file with a header and first data page.
 215  *
 216  * Returns zero on success
 217  */
 218 int ecryptfs_initialize_file(struct dentry *ecryptfs_dentry,
 219                              struct inode *ecryptfs_inode)
 220 {
 221         struct ecryptfs_crypt_stat *crypt_stat =
 222                 &ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat;
 223         int rc = 0;
 224
 225         if (S_ISDIR(ecryptfs_inode->i_mode)) {
 226                 ecryptfs_printk(KERN_DEBUG, "This is a directory\n");
 227                 crypt_stat->flags &= ~(ECRYPTFS_ENCRYPTED);
 228                 goto out;
 229         }
 230         ecryptfs_printk(KERN_DEBUG, "Initializing crypto context\n");
 231         rc = ecryptfs_new_file_context(ecryptfs_inode);
 232         if (rc) {
 233                 ecryptfs_printk(KERN_ERR, "Error creating new file "
 234                                 "context; rc = [%d]\n", rc);
 235                 goto out;
 236         }
 237         rc = ecryptfs_get_lower_file(ecryptfs_dentry, ecryptfs_inode);
 238         if (rc) {
 239                 printk(KERN_ERR "%s: Error attempting to initialize "
 240                         "the lower file for the dentry with name "
 241                         "[%pd]; rc = [%d]\n", __func__,
 242                         ecryptfs_dentry, rc);
 243                 goto out;
 244         }
 245         rc = ecryptfs_write_metadata(ecryptfs_dentry, ecryptfs_inode);
 246         if (rc)
 247                 printk(KERN_ERR "Error writing headers; rc = [%d]\n", rc);
 248         ecryptfs_put_lower_file(ecryptfs_inode);
 249 out:
 250         return rc;
 251 }
 252
 253 /**
 254  * ecryptfs_create
 255  * @dir: The inode of the directory in which to create the file.
 256  * @dentry: The eCryptfs dentry
 257  * @mode: The mode of the new file.
 258  *
 259  * Creates a new file.
 260  *
 261  * Returns zero on success; non-zero on error condition
 262  */
 263 static int
 264 ecryptfs_create(struct inode *directory_inode, struct dentry *ecryptfs_dentry,
 265                 umode_t mode, bool excl)
 266 {
 267         struct inode *ecryptfs_inode;
 268         int rc;
 269
 270         ecryptfs_inode = ecryptfs_do_create(directory_inode, ecryptfs_dentry,
 271                                             mode);
 272         if (IS_ERR(ecryptfs_inode)) {
 273                 ecryptfs_printk(KERN_WARNING, "Failed to create file in"
 274                                 "lower filesystem\n");
 275                 rc = PTR_ERR(ecryptfs_inode);
 276                 goto out;
 277         }
 278         /* At this point, a file exists on "disk"; we need to make sure
 279          * that this on disk file is prepared to be an ecryptfs file */
 280         rc = ecryptfs_initialize_file(ecryptfs_dentry, ecryptfs_inode);
 281         if (rc) {
 282                 ecryptfs_do_unlink(directory_inode, ecryptfs_dentry,
 283                                    ecryptfs_inode);
 284                 iget_failed(ecryptfs_inode);
 285                 goto out;
 286         }
 287         unlock_new_inode(ecryptfs_inode);
 288         d_instantiate(ecryptfs_dentry, ecryptfs_inode);
 289 out:
 290         return rc;
 291 }
 292
 293 static int ecryptfs_i_size_read(struct dentry *dentry, struct inode *inode)
 294 {
 295         struct ecryptfs_crypt_stat *crypt_stat;
 296         int rc;
 297
 298         rc = ecryptfs_get_lower_file(dentry, inode);
 299         if (rc) {
 300                 printk(KERN_ERR "%s: Error attempting to initialize "
 301                         "the lower file for the dentry with name "
 302                         "[%pd]; rc = [%d]\n", __func__,
 303                         dentry, rc);
 304                 return rc;
 305         }
 306
 307         crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat;
 308         /* TODO: lock for crypt_stat comparison */
 309         if (!(crypt_stat->flags & ECRYPTFS_POLICY_APPLIED))
 310                 ecryptfs_set_default_sizes(crypt_stat);
 311
 312         rc = ecryptfs_read_and_validate_header_region(inode);
 313         ecryptfs_put_lower_file(inode);
 314         if (rc) {
 315                 rc = ecryptfs_read_and_validate_xattr_region(dentry, inode);
 316                 if (!rc)
 317                         crypt_stat->flags |= ECRYPTFS_METADATA_IN_XATTR;
 318         }
 319
 320         /* Must return 0 to allow non-eCryptfs files to be looked up, too */
 321         return 0;
 322 }
 323
 324 /**
 325  * ecryptfs_lookup_interpose - Dentry interposition for a lookup
 326  */
 327 static int ecryptfs_lookup_interpose(struct dentry *dentry,
 328                                      struct dentry *lower_dentry,
 329                                      struct inode *dir_inode)
 330 {
 331         struct inode *inode, *lower_inode = d_inode(lower_dentry);
 332         struct ecryptfs_dentry_info *dentry_info;
 333         struct vfsmount *lower_mnt;
 334         int rc = 0;
 335
 336         dentry_info = kmem_cache_alloc(ecryptfs_dentry_info_cache, GFP_KERNEL);
 337         if (!dentry_info) {
 338                 printk(KERN_ERR "%s: Out of memory whilst attempting "
 339                        "to allocate ecryptfs_dentry_info struct\n",
 340                         __func__);
 341                 dput(lower_dentry);
 342                 return -ENOMEM;
 343         }
 344
 345         lower_mnt = mntget(ecryptfs_dentry_to_lower_mnt(dentry->d_parent));
 346         fsstack_copy_attr_atime(dir_inode, d_inode(lower_dentry->d_parent));
 347         BUG_ON(!d_count(lower_dentry));
 348
 349         ecryptfs_set_dentry_private(dentry, dentry_info);
 350         dentry_info->lower_path.mnt = lower_mnt;
 351         dentry_info->lower_path.dentry = lower_dentry;
 352
 353         if (d_really_is_negative(lower_dentry)) {
 354                 /* We want to add because we couldn't find in lower */
 355                 d_add(dentry, NULL);
 356                 return 0;
 357         }
 358         inode = __ecryptfs_get_inode(lower_inode, dir_inode->i_sb);
 359         if (IS_ERR(inode)) {
 360                 printk(KERN_ERR "%s: Error interposing; rc = [%ld]\n",
 361                        __func__, PTR_ERR(inode));
 362                 return PTR_ERR(inode);
 363         }
 364         if (S_ISREG(inode->i_mode)) {
 365                 rc = ecryptfs_i_size_read(dentry, inode);
 366                 if (rc) {
 367                         make_bad_inode(inode);
 368                         return rc;
 369                 }
 370         }
 371
 372         if (inode->i_state & I_NEW)
 373                 unlock_new_inode(inode);
 374         d_add(dentry, inode);
 375
 376         return rc;
 377 }
 378
 379 /**
 380  * ecryptfs_lookup
 381  * @ecryptfs_dir_inode: The eCryptfs directory inode
 382  * @ecryptfs_dentry: The eCryptfs dentry that we are looking up
 383  * @flags: lookup flags
 384  *
 385  * Find a file on disk. If the file does not exist, then we'll add it to the
 386  * dentry cache and continue on to read it from the disk.
 387  */
 388 static struct dentry *ecryptfs_lookup(struct inode *ecryptfs_dir_inode,
 389                                       struct dentry *ecryptfs_dentry,
 390                                       unsigned int flags)
 391 {
 392         char *encrypted_and_encoded_name = NULL;
 393         size_t encrypted_and_encoded_name_size;
 394         struct ecryptfs_mount_crypt_stat *mount_crypt_stat = NULL;
 395         struct dentry *lower_dir_dentry, *lower_dentry;
 396         int rc = 0;
 397
 398         lower_dir_dentry = ecryptfs_dentry_to_lower(ecryptfs_dentry->d_parent);
 399         inode_lock(d_inode(lower_dir_dentry));
 400         lower_dentry = lookup_one_len(ecryptfs_dentry->d_name.name,
 401                                       lower_dir_dentry,
 402                                       ecryptfs_dentry->d_name.len);
 403         inode_unlock(d_inode(lower_dir_dentry));
 404         if (IS_ERR(lower_dentry)) {
 405                 rc = PTR_ERR(lower_dentry);
 406                 ecryptfs_printk(KERN_DEBUG, "%s: lookup_one_len() returned "
 407                                 "[%d] on lower_dentry = [%pd]\n", __func__, rc,
 408                                 ecryptfs_dentry);
 409                 goto out;
 410         }
 411         if (d_really_is_positive(lower_dentry))
 412                 goto interpose;
 413         mount_crypt_stat = &ecryptfs_superblock_to_private(
 414                                 ecryptfs_dentry->d_sb)->mount_crypt_stat;
 415         if (!(mount_crypt_stat
 416             && (mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES)))
 417                 goto interpose;
 418         dput(lower_dentry);
 419         rc = ecryptfs_encrypt_and_encode_filename(
 420                 &encrypted_and_encoded_name, &encrypted_and_encoded_name_size,
 421                 NULL, mount_crypt_stat, ecryptfs_dentry->d_name.name,
 422                 ecryptfs_dentry->d_name.len);
 423         if (rc) {
 424                 printk(KERN_ERR "%s: Error attempting to encrypt and encode "
 425                        "filename; rc = [%d]\n", __func__, rc);
 426                 goto out;
 427         }
 428         inode_lock(d_inode(lower_dir_dentry));
 429         lower_dentry = lookup_one_len(encrypted_and_encoded_name,
 430                                       lower_dir_dentry,
 431                                       encrypted_and_encoded_name_size);
 432         inode_unlock(d_inode(lower_dir_dentry));
 433         if (IS_ERR(lower_dentry)) {
 434                 rc = PTR_ERR(lower_dentry);
 435                 ecryptfs_printk(KERN_DEBUG, "%s: lookup_one_len() returned "
 436                                 "[%d] on lower_dentry = [%s]\n", __func__, rc,
 437                                 encrypted_and_encoded_name);
 438                 goto out;
 439         }
 440 interpose:
 441         rc = ecryptfs_lookup_interpose(ecryptfs_dentry, lower_dentry,
 442                                        ecryptfs_dir_inode);
 443 out:
 444         kfree(encrypted_and_encoded_name);
 445         return ERR_PTR(rc);
 446 }
 447
 448 static int ecryptfs_link(struct dentry *old_dentry, struct inode *dir,
 449                          struct dentry *new_dentry)
 450 {
 451         struct dentry *lower_old_dentry;
 452         struct dentry *lower_new_dentry;
 453         struct dentry *lower_dir_dentry;
 454         u64 file_size_save;
 455         int rc;
 456
 457         file_size_save = i_size_read(d_inode(old_dentry));
 458         lower_old_dentry = ecryptfs_dentry_to_lower(old_dentry);
 459         lower_new_dentry = ecryptfs_dentry_to_lower(new_dentry);
 460         dget(lower_old_dentry);
 461         dget(lower_new_dentry);
 462         lower_dir_dentry = lock_parent(lower_new_dentry);
 463         rc = vfs_link(lower_old_dentry, d_inode(lower_dir_dentry),
 464                       lower_new_dentry, NULL);
 465         if (rc || d_really_is_negative(lower_new_dentry))
 466                 goto out_lock;
 467         rc = ecryptfs_interpose(lower_new_dentry, new_dentry, dir->i_sb);
 468         if (rc)
 469                 goto out_lock;
 470         fsstack_copy_attr_times(dir, d_inode(lower_dir_dentry));
 471         fsstack_copy_inode_size(dir, d_inode(lower_dir_dentry));
 472         set_nlink(d_inode(old_dentry),
 473                   ecryptfs_inode_to_lower(d_inode(old_dentry))->i_nlink);
 474         i_size_write(d_inode(new_dentry), file_size_save);
 475 out_lock:
 476         unlock_dir(lower_dir_dentry);
 477         dput(lower_new_dentry);
 478         dput(lower_old_dentry);
 479         return rc;
 480 }
 481
 482 static int ecryptfs_unlink(struct inode *dir, struct dentry *dentry)
 483 {
 484         return ecryptfs_do_unlink(dir, dentry, d_inode(dentry));
 485 }
 486
 487 static int ecryptfs_symlink(struct inode *dir, struct dentry *dentry,
 488                             const char *symname)
 489 {
 490         int rc;
 491         struct dentry *lower_dentry;
 492         struct dentry *lower_dir_dentry;
 493         char *encoded_symname;
 494         size_t encoded_symlen;
 495         struct ecryptfs_mount_crypt_stat *mount_crypt_stat = NULL;
 496
 497         lower_dentry = ecryptfs_dentry_to_lower(dentry);
 498         dget(lower_dentry);
 499         lower_dir_dentry = lock_parent(lower_dentry);
 500         mount_crypt_stat = &ecryptfs_superblock_to_private(
 501                 dir->i_sb)->mount_crypt_stat;
 502         rc = ecryptfs_encrypt_and_encode_filename(&encoded_symname,
 503                                                   &encoded_symlen,
 504                                                   NULL,
 505                                                   mount_crypt_stat, symname,
 506                                                   strlen(symname));
 507         if (rc)
 508                 goto out_lock;
 509         rc = vfs_symlink(d_inode(lower_dir_dentry), lower_dentry,
 510                          encoded_symname);
 511         kfree(encoded_symname);
 512         if (rc || d_really_is_negative(lower_dentry))
 513                 goto out_lock;
 514         rc = ecryptfs_interpose(lower_dentry, dentry, dir->i_sb);
 515         if (rc)
 516                 goto out_lock;
 517         fsstack_copy_attr_times(dir, d_inode(lower_dir_dentry));
 518         fsstack_copy_inode_size(dir, d_inode(lower_dir_dentry));
 519 out_lock:
 520         unlock_dir(lower_dir_dentry);
 521         dput(lower_dentry);
 522         if (d_really_is_negative(dentry))
 523                 d_drop(dentry);
 524         return rc;
 525 }
 526
 527 static int ecryptfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
 528 {
 529         int rc;
 530         struct dentry *lower_dentry;
 531         struct dentry *lower_dir_dentry;
 532
 533         lower_dentry = ecryptfs_dentry_to_lower(dentry);
 534         lower_dir_dentry = lock_parent(lower_dentry);
 535         rc = vfs_mkdir(d_inode(lower_dir_dentry), lower_dentry, mode);
 536         if (rc || d_really_is_negative(lower_dentry))
 537                 goto out;
 538         rc = ecryptfs_interpose(lower_dentry, dentry, dir->i_sb);
 539         if (rc)
 540                 goto out;
 541         fsstack_copy_attr_times(dir, d_inode(lower_dir_dentry));
 542         fsstack_copy_inode_size(dir, d_inode(lower_dir_dentry));
 543         set_nlink(dir, d_inode(lower_dir_dentry)->i_nlink);
 544 out:
 545         unlock_dir(lower_dir_dentry);
 546         if (d_really_is_negative(dentry))
 547                 d_drop(dentry);
 548         return rc;
 549 }
 550
 551 static int ecryptfs_rmdir(struct inode *dir, struct dentry *dentry)
 552 {
 553         struct dentry *lower_dentry;
 554         struct dentry *lower_dir_dentry;
 555         int rc;
 556
 557         lower_dentry = ecryptfs_dentry_to_lower(dentry);
 558         dget(dentry);
 559         lower_dir_dentry = lock_parent(lower_dentry);
 560         dget(lower_dentry);
 561         rc = vfs_rmdir(d_inode(lower_dir_dentry), lower_dentry);
 562         dput(lower_dentry);
 563         if (!rc && d_really_is_positive(dentry))
 564                 clear_nlink(d_inode(dentry));
 565         fsstack_copy_attr_times(dir, d_inode(lower_dir_dentry));
 566         set_nlink(dir, d_inode(lower_dir_dentry)->i_nlink);
 567         unlock_dir(lower_dir_dentry);
 568         if (!rc)
 569                 d_drop(dentry);
 570         dput(dentry);
 571         return rc;
 572 }
 573
 574 static int
 575 ecryptfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev)
 576 {
 577         int rc;
 578         struct dentry *lower_dentry;
 579         struct dentry *lower_dir_dentry;
 580
 581         lower_dentry = ecryptfs_dentry_to_lower(dentry);
 582         lower_dir_dentry = lock_parent(lower_dentry);
 583         rc = vfs_mknod(d_inode(lower_dir_dentry), lower_dentry, mode, dev);
 584         if (rc || d_really_is_negative(lower_dentry))
 585                 goto out;
 586         rc = ecryptfs_interpose(lower_dentry, dentry, dir->i_sb);
 587         if (rc)
 588                 goto out;
 589         fsstack_copy_attr_times(dir, d_inode(lower_dir_dentry));
 590         fsstack_copy_inode_size(dir, d_inode(lower_dir_dentry));
 591 out:
 592         unlock_dir(lower_dir_dentry);
 593         if (d_really_is_negative(dentry))
 594                 d_drop(dentry);
 595         return rc;
 596 }
 597
 598 static int
 599 ecryptfs_rename(struct inode *old_dir, struct dentry *old_dentry,
 600                 struct inode *new_dir, struct dentry *new_dentry)
 601 {
 602         int rc;
 603         struct dentry *lower_old_dentry;
 604         struct dentry *lower_new_dentry;
 605         struct dentry *lower_old_dir_dentry;
 606         struct dentry *lower_new_dir_dentry;
 607         struct dentry *trap = NULL;
 608         struct inode *target_inode;
 609
 610         lower_old_dentry = ecryptfs_dentry_to_lower(old_dentry);
 611         lower_new_dentry = ecryptfs_dentry_to_lower(new_dentry);
 612         dget(lower_old_dentry);
 613         dget(lower_new_dentry);
 614         lower_old_dir_dentry = dget_parent(lower_old_dentry);
 615         lower_new_dir_dentry = dget_parent(lower_new_dentry);
 616         target_inode = d_inode(new_dentry);
 617         trap = lock_rename(lower_old_dir_dentry, lower_new_dir_dentry);
 618         /* source should not be ancestor of target */
 619         if (trap == lower_old_dentry) {
 620                 rc = -EINVAL;
 621                 goto out_lock;
 622         }
 623         /* target should not be ancestor of source */
 624         if (trap == lower_new_dentry) {
 625                 rc = -ENOTEMPTY;
 626                 goto out_lock;
 627         }
 628         rc = vfs_rename(d_inode(lower_old_dir_dentry), lower_old_dentry,
 629                         d_inode(lower_new_dir_dentry), lower_new_dentry,
 630                         NULL, 0);
 631         if (rc)
 632                 goto out_lock;
 633         if (target_inode)
 634                 fsstack_copy_attr_all(target_inode,
 635                                       ecryptfs_inode_to_lower(target_inode));
 636         fsstack_copy_attr_all(new_dir, d_inode(lower_new_dir_dentry));
 637         if (new_dir != old_dir)
 638                 fsstack_copy_attr_all(old_dir, d_inode(lower_old_dir_dentry));
 639 out_lock:
 640         unlock_rename(lower_old_dir_dentry, lower_new_dir_dentry);
 641         dput(lower_new_dir_dentry);
 642         dput(lower_old_dir_dentry);
 643         dput(lower_new_dentry);
 644         dput(lower_old_dentry);
 645         return rc;
 646 }
 647
 648 static char *ecryptfs_readlink_lower(struct dentry *dentry, size_t *bufsiz)
 649 {
 650         struct dentry *lower_dentry = ecryptfs_dentry_to_lower(dentry);
 651         char *lower_buf;
 652         char *buf;
 653         mm_segment_t old_fs;
 654         int rc;
 655
 656         lower_buf = kmalloc(PATH_MAX, GFP_KERNEL);
 657         if (!lower_buf)
 658                 return ERR_PTR(-ENOMEM);
 659         old_fs = get_fs();
 660         set_fs(get_ds());
 661         rc = d_inode(lower_dentry)->i_op->readlink(lower_dentry,
 662                                                    (char __user *)lower_buf,
 663                                                    PATH_MAX);
 664         set_fs(old_fs);
 665         if (rc < 0)
 666                 goto out;
 667         rc = ecryptfs_decode_and_decrypt_filename(&buf, bufsiz, dentry->d_sb,
 668                                                   lower_buf, rc);
 669 out:
 670         kfree(lower_buf);
 671         return rc ? ERR_PTR(rc) : buf;
 672 }
 673
 674 static const char *ecryptfs_get_link(struct dentry *dentry,
 675                                      struct inode *inode,
 676                                      struct delayed_call *done)
 677 {
 678         size_t len;
 679         char *buf;
 680
 681         if (!dentry)
 682                 return ERR_PTR(-ECHILD);
 683
 684         buf = ecryptfs_readlink_lower(dentry, &len);
 685         if (IS_ERR(buf))
 686                 return buf;
 687         fsstack_copy_attr_atime(d_inode(dentry),
 688                                 d_inode(ecryptfs_dentry_to_lower(dentry)));
 689         buf[len] = '\0';
 690         set_delayed_call(done, kfree_link, buf);
 691         return buf;
 692 }
 693
 694 /**
 695  * upper_size_to_lower_size
 696  * @crypt_stat: Crypt_stat associated with file
 697  * @upper_size: Size of the upper file
 698  *
 699  * Calculate the required size of the lower file based on the
 700  * specified size of the upper file. This calculation is based on the
 701  * number of headers in the underlying file and the extent size.
 702  *
 703  * Returns Calculated size of the lower file.
 704  */
 705 static loff_t
 706 upper_size_to_lower_size(struct ecryptfs_crypt_stat *crypt_stat,
 707                          loff_t upper_size)
 708 {
 709         loff_t lower_size;
 710
 711         lower_size = ecryptfs_lower_header_size(crypt_stat);
 712         if (upper_size != 0) {
 713                 loff_t num_extents;
 714
 715                 num_extents = upper_size >> crypt_stat->extent_shift;
 716                 if (upper_size & ~crypt_stat->extent_mask)
 717                         num_extents++;
 718                 lower_size += (num_extents * crypt_stat->extent_size);
 719         }
 720         return lower_size;
 721 }
 722
 723 /**
 724  * truncate_upper
 725  * @dentry: The ecryptfs layer dentry
 726  * @ia: Address of the ecryptfs inode's attributes
 727  * @lower_ia: Address of the lower inode's attributes
 728  *
 729  * Function to handle truncations modifying the size of the file. Note
 730  * that the file sizes are interpolated. When expanding, we are simply
 731  * writing strings of 0's out. When truncating, we truncate the upper
 732  * inode and update the lower_ia according to the page index
 733  * interpolations. If ATTR_SIZE is set in lower_ia->ia_valid upon return,
 734  * the caller must use lower_ia in a call to notify_change() to perform
 735  * the truncation of the lower inode.
 736  *
 737  * Returns zero on success; non-zero otherwise
 738  */
 739 static int truncate_upper(struct dentry *dentry, struct iattr *ia,
 740                           struct iattr *lower_ia)
 741 {
 742         int rc = 0;
 743         struct inode *inode = d_inode(dentry);
 744         struct ecryptfs_crypt_stat *crypt_stat;
 745         loff_t i_size = i_size_read(inode);
 746         loff_t lower_size_before_truncate;
 747         loff_t lower_size_after_truncate;
 748
 749         if (unlikely((ia->ia_size == i_size))) {
 750                 lower_ia->ia_valid &= ~ATTR_SIZE;
 751                 return 0;
 752         }
 753         rc = ecryptfs_get_lower_file(dentry, inode);
 754         if (rc)
 755                 return rc;
 756         crypt_stat = &ecryptfs_inode_to_private(d_inode(dentry))->crypt_stat;
 757         /* Switch on growing or shrinking file */
 758         if (ia->ia_size > i_size) {
 759                 char zero[] = { 0x00 };
 760
 761                 lower_ia->ia_valid &= ~ATTR_SIZE;
 762                 /* Write a single 0 at the last position of the file;
 763                  * this triggers code that will fill in 0's throughout
 764                  * the intermediate portion of the previous end of the
 765                  * file and the new and of the file */
 766                 rc = ecryptfs_write(inode, zero,
 767                                     (ia->ia_size - 1), 1);
 768         } else { /* ia->ia_size < i_size_read(inode) */
 769                 /* We're chopping off all the pages down to the page
 770                  * in which ia->ia_size is located. Fill in the end of
 771                  * that page from (ia->ia_size & ~PAGE_CACHE_MASK) to
 772                  * PAGE_CACHE_SIZE with zeros. */
 773                 size_t num_zeros = (PAGE_CACHE_SIZE
 774                                     - (ia->ia_size & ~PAGE_CACHE_MASK));
 775
 776                 if (!(crypt_stat->flags & ECRYPTFS_ENCRYPTED)) {
 777                         truncate_setsize(inode, ia->ia_size);
 778                         lower_ia->ia_size = ia->ia_size;
 779                         lower_ia->ia_valid |= ATTR_SIZE;
 780                         goto out;
 781                 }
 782                 if (num_zeros) {
 783                         char *zeros_virt;
 784
 785                         zeros_virt = kzalloc(num_zeros, GFP_KERNEL);
 786                         if (!zeros_virt) {
 787                                 rc = -ENOMEM;
 788                                 goto out;
 789                         }
 790                         rc = ecryptfs_write(inode, zeros_virt,
 791                                             ia->ia_size, num_zeros);
 792                         kfree(zeros_virt);
 793                         if (rc) {
 794                                 printk(KERN_ERR "Error attempting to zero out "
 795                                        "the remainder of the end page on "
 796                                        "reducing truncate; rc = [%d]\n", rc);
 797                                 goto out;
 798                         }
 799                 }
 800                 truncate_setsize(inode, ia->ia_size);
 801                 rc = ecryptfs_write_inode_size_to_metadata(inode);
 802                 if (rc) {
 803                         printk(KERN_ERR "Problem with "
 804                                "ecryptfs_write_inode_size_to_metadata; "
 805                                "rc = [%d]\n", rc);
 806                         goto out;
 807                 }
 808                 /* We are reducing the size of the ecryptfs file, and need to
 809                  * know if we need to reduce the size of the lower file. */
 810                 lower_size_before_truncate =
 811                     upper_size_to_lower_size(crypt_stat, i_size);
 812                 lower_size_after_truncate =
 813                     upper_size_to_lower_size(crypt_stat, ia->ia_size);
 814                 if (lower_size_after_truncate < lower_size_before_truncate) {
 815                         lower_ia->ia_size = lower_size_after_truncate;
 816                         lower_ia->ia_valid |= ATTR_SIZE;
 817                 } else
 818                         lower_ia->ia_valid &= ~ATTR_SIZE;
 819         }
 820 out:
 821         ecryptfs_put_lower_file(inode);
 822         return rc;
 823 }
 824
 825 static int ecryptfs_inode_newsize_ok(struct inode *inode, loff_t offset)
 826 {
 827         struct ecryptfs_crypt_stat *crypt_stat;
 828         loff_t lower_oldsize, lower_newsize;
 829
 830         crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat;
 831         lower_oldsize = upper_size_to_lower_size(crypt_stat,
 832                                                  i_size_read(inode));
 833         lower_newsize = upper_size_to_lower_size(crypt_stat, offset);
 834         if (lower_newsize > lower_oldsize) {
 835                 /*
 836                  * The eCryptfs inode and the new *lower* size are mixed here
 837                  * because we may not have the lower i_mutex held and/or it may
 838                  * not be appropriate to call inode_newsize_ok() with inodes
 839                  * from other filesystems.
 840                  */
 841                 return inode_newsize_ok(inode, lower_newsize);
 842         }
 843
 844         return 0;
 845 }
 846
 847 /**
 848  * ecryptfs_truncate
 849  * @dentry: The ecryptfs layer dentry
 850  * @new_length: The length to expand the file to
 851  *
 852  * Simple function that handles the truncation of an eCryptfs inode and
 853  * its corresponding lower inode.
 854  *
 855  * Returns zero on success; non-zero otherwise
 856  */
 857 int ecryptfs_truncate(struct dentry *dentry, loff_t new_length)
 858 {
 859         struct iattr ia = { .ia_valid = ATTR_SIZE, .ia_size = new_length };
 860         struct iattr lower_ia = { .ia_valid = 0 };
 861         int rc;
 862
 863         rc = ecryptfs_inode_newsize_ok(d_inode(dentry), new_length);
 864         if (rc)
 865                 return rc;
 866
 867         rc = truncate_upper(dentry, &ia, &lower_ia);
 868         if (!rc && lower_ia.ia_valid & ATTR_SIZE) {
 869                 struct dentry *lower_dentry = ecryptfs_dentry_to_lower(dentry);
 870
 871                 inode_lock(d_inode(lower_dentry));
 872                 rc = notify_change(lower_dentry, &lower_ia, NULL);
 873                 inode_unlock(d_inode(lower_dentry));
 874         }
 875         return rc;
 876 }
 877
 878 static int
 879 ecryptfs_permission(struct inode *inode, int mask)
 880 {
 881         return inode_permission(ecryptfs_inode_to_lower(inode), mask);
 882 }
 883
 884 /**
 885  * ecryptfs_setattr
 886  * @dentry: dentry handle to the inode to modify
 887  * @ia: Structure with flags of what to change and values
 888  *
 889  * Updates the metadata of an inode. If the update is to the size
 890  * i.e. truncation, then ecryptfs_truncate will handle the size modification
 891  * of both the ecryptfs inode and the lower inode.
 892  *
 893  * All other metadata changes will be passed right to the lower filesystem,
 894  * and we will just update our inode to look like the lower.
 895  */
 896 static int ecryptfs_setattr(struct dentry *dentry, struct iattr *ia)
 897 {
 898         int rc = 0;
 899         struct dentry *lower_dentry;
 900         struct iattr lower_ia;
 901         struct inode *inode;
 902         struct inode *lower_inode;
 903         struct ecryptfs_crypt_stat *crypt_stat;
 904
 905         crypt_stat = &ecryptfs_inode_to_private(d_inode(dentry))->crypt_stat;
 906         if (!(crypt_stat->flags & ECRYPTFS_STRUCT_INITIALIZED))
 907                 ecryptfs_init_crypt_stat(crypt_stat);
 908         inode = d_inode(dentry);
 909         lower_inode = ecryptfs_inode_to_lower(inode);
 910         lower_dentry = ecryptfs_dentry_to_lower(dentry);
 911         mutex_lock(&crypt_stat->cs_mutex);
 912         if (d_is_dir(dentry))
 913                 crypt_stat->flags &= ~(ECRYPTFS_ENCRYPTED);
 914         else if (d_is_reg(dentry)
 915                  && (!(crypt_stat->flags & ECRYPTFS_POLICY_APPLIED)
 916                      || !(crypt_stat->flags & ECRYPTFS_KEY_VALID))) {
 917                 struct ecryptfs_mount_crypt_stat *mount_crypt_stat;
 918
 919                 mount_crypt_stat = &ecryptfs_superblock_to_private(
 920                         dentry->d_sb)->mount_crypt_stat;
 921                 rc = ecryptfs_get_lower_file(dentry, inode);
 922                 if (rc) {
 923                         mutex_unlock(&crypt_stat->cs_mutex);
 924                         goto out;
 925                 }
 926                 rc = ecryptfs_read_metadata(dentry);
 927                 ecryptfs_put_lower_file(inode);
 928                 if (rc) {
 929                         if (!(mount_crypt_stat->flags
 930                               & ECRYPTFS_PLAINTEXT_PASSTHROUGH_ENABLED)) {
 931                                 rc = -EIO;
 932                                 printk(KERN_WARNING "Either the lower file "
 933                                        "is not in a valid eCryptfs format, "
 934                                        "or the key could not be retrieved. "
 935                                        "Plaintext passthrough mode is not "
 936                                        "enabled; returning -EIO\n");
 937                                 mutex_unlock(&crypt_stat->cs_mutex);
 938                                 goto out;
 939                         }
 940                         rc = 0;
 941                         crypt_stat->flags &= ~(ECRYPTFS_I_SIZE_INITIALIZED
 942                                                | ECRYPTFS_ENCRYPTED);
 943                 }
 944         }
 945         mutex_unlock(&crypt_stat->cs_mutex);
 946
 947         rc = inode_change_ok(inode, ia);
 948         if (rc)
 949                 goto out;
 950         if (ia->ia_valid & ATTR_SIZE) {
 951                 rc = ecryptfs_inode_newsize_ok(inode, ia->ia_size);
 952                 if (rc)
 953                         goto out;
 954         }
 955
 956         memcpy(&lower_ia, ia, sizeof(lower_ia));
 957         if (ia->ia_valid & ATTR_FILE)
 958                 lower_ia.ia_file = ecryptfs_file_to_lower(ia->ia_file);
 959         if (ia->ia_valid & ATTR_SIZE) {
 960                 rc = truncate_upper(dentry, ia, &lower_ia);
 961                 if (rc < 0)
 962                         goto out;
 963         }
 964
 965         /*
 966          * mode change is for clearing setuid/setgid bits. Allow lower fs
 967          * to interpret this in its own way.
 968          */
 969         if (lower_ia.ia_valid & (ATTR_KILL_SUID | ATTR_KILL_SGID))
 970                 lower_ia.ia_valid &= ~ATTR_MODE;
 971
 972         inode_lock(d_inode(lower_dentry));
 973         rc = notify_change(lower_dentry, &lower_ia, NULL);
 974         inode_unlock(d_inode(lower_dentry));
 975 out:
 976         fsstack_copy_attr_all(inode, lower_inode);
 977         return rc;
 978 }
 979
 980 static int ecryptfs_getattr_link(struct vfsmount *mnt, struct dentry *dentry,
 981                                  struct kstat *stat)
 982 {
 983         struct ecryptfs_mount_crypt_stat *mount_crypt_stat;
 984         int rc = 0;
 985
 986         mount_crypt_stat = &ecryptfs_superblock_to_private(
 987                                                 dentry->d_sb)->mount_crypt_stat;
 988         generic_fillattr(d_inode(dentry), stat);
 989         if (mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES) {
 990                 char *target;
 991                 size_t targetsiz;
 992
 993                 target = ecryptfs_readlink_lower(dentry, &targetsiz);
 994                 if (!IS_ERR(target)) {
 995                         kfree(target);
 996                         stat->size = targetsiz;
 997                 } else {
 998                         rc = PTR_ERR(target);
 999                 }
1000         }
1001         return rc;
1002 }
1003
1004 static int ecryptfs_getattr(struct vfsmount *mnt, struct dentry *dentry,
1005                             struct kstat *stat)
1006 {
1007         struct kstat lower_stat;
1008         int rc;
1009
1010         rc = vfs_getattr(ecryptfs_dentry_to_lower_path(dentry), &lower_stat);
1011         if (!rc) {
1012                 fsstack_copy_attr_all(d_inode(dentry),
1013                                       ecryptfs_inode_to_lower(d_inode(dentry)));
1014                 generic_fillattr(d_inode(dentry), stat);
1015                 stat->blocks = lower_stat.blocks;
1016         }
1017         return rc;
1018 }
1019
1020 int
1021 ecryptfs_setxattr(struct dentry *dentry, const char *name, const void *value,
1022                   size_t size, int flags)
1023 {
1024         int rc = 0;
1025         struct dentry *lower_dentry;
1026
1027         lower_dentry = ecryptfs_dentry_to_lower(dentry);
1028         if (!d_inode(lower_dentry)->i_op->setxattr) {
1029                 rc = -EOPNOTSUPP;
1030                 goto out;
1031         }
1032
1033         rc = vfs_setxattr(lower_dentry, name, value, size, flags);
1034         if (!rc && d_really_is_positive(dentry))
1035                 fsstack_copy_attr_all(d_inode(dentry), d_inode(lower_dentry));
1036 out:
1037         return rc;
1038 }
1039
1040 ssize_t
1041 ecryptfs_getxattr_lower(struct dentry *lower_dentry, const char *name,
1042                         void *value, size_t size)
1043 {
1044         int rc = 0;
1045
1046         if (!d_inode(lower_dentry)->i_op->getxattr) {
1047                 rc = -EOPNOTSUPP;
1048                 goto out;
1049         }
1050         inode_lock(d_inode(lower_dentry));
1051         rc = d_inode(lower_dentry)->i_op->getxattr(lower_dentry, name, value,
1052                                                    size);
1053         inode_unlock(d_inode(lower_dentry));
1054 out:
1055         return rc;
1056 }
1057
1058 static ssize_t
1059 ecryptfs_getxattr(struct dentry *dentry, const char *name, void *value,
1060                   size_t size)
1061 {
1062         return ecryptfs_getxattr_lower(ecryptfs_dentry_to_lower(dentry), name,
1063                                        value, size);
1064 }
1065
1066 static ssize_t
1067 ecryptfs_listxattr(struct dentry *dentry, char *list, size_t size)
1068 {
1069         int rc = 0;
1070         struct dentry *lower_dentry;
1071
1072         lower_dentry = ecryptfs_dentry_to_lower(dentry);
1073         if (!d_inode(lower_dentry)->i_op->listxattr) {
1074                 rc = -EOPNOTSUPP;
1075                 goto out;
1076         }
1077         inode_lock(d_inode(lower_dentry));
1078         rc = d_inode(lower_dentry)->i_op->listxattr(lower_dentry, list, size);
1079         inode_unlock(d_inode(lower_dentry));
1080 out:
1081         return rc;
1082 }
1083
1084 static int ecryptfs_removexattr(struct dentry *dentry, const char *name)
1085 {
1086         int rc = 0;
1087         struct dentry *lower_dentry;
1088
1089         lower_dentry = ecryptfs_dentry_to_lower(dentry);
1090         if (!d_inode(lower_dentry)->i_op->removexattr) {
1091                 rc = -EOPNOTSUPP;
1092                 goto out;
1093         }
1094         inode_lock(d_inode(lower_dentry));
1095         rc = d_inode(lower_dentry)->i_op->removexattr(lower_dentry, name);
1096         inode_unlock(d_inode(lower_dentry));
1097 out:
1098         return rc;
1099 }
1100
1101 const struct inode_operations ecryptfs_symlink_iops = {
1102         .readlink = generic_readlink,
1103         .get_link = ecryptfs_get_link,
1104         .permission = ecryptfs_permission,
1105         .setattr = ecryptfs_setattr,
1106         .getattr = ecryptfs_getattr_link,
1107         .setxattr = ecryptfs_setxattr,
1108         .getxattr = ecryptfs_getxattr,
1109         .listxattr = ecryptfs_listxattr,
1110         .removexattr = ecryptfs_removexattr
1111 };
1112
1113 const struct inode_operations ecryptfs_dir_iops = {
1114         .create = ecryptfs_create,
1115         .lookup = ecryptfs_lookup,
1116         .link = ecryptfs_link,
1117         .unlink = ecryptfs_unlink,
1118         .symlink = ecryptfs_symlink,
1119         .mkdir = ecryptfs_mkdir,
1120         .rmdir = ecryptfs_rmdir,
1121         .mknod = ecryptfs_mknod,
1122         .rename = ecryptfs_rename,
1123         .permission = ecryptfs_permission,
1124         .setattr = ecryptfs_setattr,
1125         .setxattr = ecryptfs_setxattr,
1126         .getxattr = ecryptfs_getxattr,
1127         .listxattr = ecryptfs_listxattr,
1128         .removexattr = ecryptfs_removexattr
1129 };
1130
1131 const struct inode_operations ecryptfs_main_iops = {
1132         .permission = ecryptfs_permission,
1133         .setattr = ecryptfs_setattr,
1134         .getattr = ecryptfs_getattr,
1135         .setxattr = ecryptfs_setxattr,
1136         .getxattr = ecryptfs_getxattr,
1137         .listxattr = ecryptfs_listxattr,
1138         .removexattr = ecryptfs_removexattr
1139 };