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