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         unlock_new_inode(ecryptfs_inode);
 291         d_instantiate(ecryptfs_dentry, ecryptfs_inode);
 292 out:
 293         return rc;
 294 }
 295
 296 static int ecryptfs_i_size_read(struct dentry *dentry, struct inode *inode)
 297 {
 298         struct ecryptfs_crypt_stat *crypt_stat;
 299         int rc;
 300
 301         rc = ecryptfs_get_lower_file(dentry, inode);
 302         if (rc) {
 303                 printk(KERN_ERR "%s: Error attempting to initialize "
 304                         "the lower file for the dentry with name "
 305                         "[%pd]; rc = [%d]\n", __func__,
 306                         dentry, rc);
 307                 return rc;
 308         }
 309
 310         crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat;
 311         /* TODO: lock for crypt_stat comparison */
 312         if (!(crypt_stat->flags & ECRYPTFS_POLICY_APPLIED))
 313                 ecryptfs_set_default_sizes(crypt_stat);
 314
 315         rc = ecryptfs_read_and_validate_header_region(inode);
 316         ecryptfs_put_lower_file(inode);
 317         if (rc) {
 318                 rc = ecryptfs_read_and_validate_xattr_region(dentry, inode);
 319                 if (!rc)
 320                         crypt_stat->flags |= ECRYPTFS_METADATA_IN_XATTR;
 321         }
 322
 323         /* Must return 0 to allow non-eCryptfs files to be looked up, too */
 324         return 0;
 325 }
 326
 327 /**
 328  * ecryptfs_lookup_interpose - Dentry interposition for a lookup
 329  */
 330 static int ecryptfs_lookup_interpose(struct dentry *dentry,
 331                                      struct dentry *lower_dentry,
 332                                      struct inode *dir_inode)
 333 {
 334         struct inode *inode, *lower_inode = d_inode(lower_dentry);
 335         struct ecryptfs_dentry_info *dentry_info;
 336         struct vfsmount *lower_mnt;
 337         int rc = 0;
 338
 339         dentry_info = kmem_cache_alloc(ecryptfs_dentry_info_cache, GFP_KERNEL);
 340         if (!dentry_info) {
 341                 printk(KERN_ERR "%s: Out of memory whilst attempting "
 342                        "to allocate ecryptfs_dentry_info struct\n",
 343                         __func__);
 344                 dput(lower_dentry);
 345                 return -ENOMEM;
 346         }
 347
 348         lower_mnt = mntget(ecryptfs_dentry_to_lower_mnt(dentry->d_parent));
 349         fsstack_copy_attr_atime(dir_inode, d_inode(lower_dentry->d_parent));
 350         BUG_ON(!d_count(lower_dentry));
 351
 352         ecryptfs_set_dentry_private(dentry, dentry_info);
 353         dentry_info->lower_path.mnt = lower_mnt;
 354         dentry_info->lower_path.dentry = lower_dentry;
 355
 356         if (d_really_is_negative(lower_dentry)) {
 357                 /* We want to add because we couldn't find in lower */
 358                 d_add(dentry, NULL);
 359                 return 0;
 360         }
 361         inode = __ecryptfs_get_inode(lower_inode, dir_inode->i_sb);
 362         if (IS_ERR(inode)) {
 363                 printk(KERN_ERR "%s: Error interposing; rc = [%ld]\n",
 364                        __func__, PTR_ERR(inode));
 365                 return PTR_ERR(inode);
 366         }
 367         if (S_ISREG(inode->i_mode)) {
 368                 rc = ecryptfs_i_size_read(dentry, inode);
 369                 if (rc) {
 370                         make_bad_inode(inode);
 371                         return rc;
 372                 }
 373         }
 374
 375         if (inode->i_state & I_NEW)
 376                 unlock_new_inode(inode);
 377         d_add(dentry, inode);
 378
 379         return rc;
 380 }
 381
 382 /**
 383  * ecryptfs_lookup
 384  * @ecryptfs_dir_inode: The eCryptfs directory inode
 385  * @ecryptfs_dentry: The eCryptfs dentry that we are looking up
 386  * @flags: lookup flags
 387  *
 388  * Find a file on disk. If the file does not exist, then we'll add it to the
 389  * dentry cache and continue on to read it from the disk.
 390  */
 391 static struct dentry *ecryptfs_lookup(struct inode *ecryptfs_dir_inode,
 392                                       struct dentry *ecryptfs_dentry,
 393                                       unsigned int flags)
 394 {
 395         char *encrypted_and_encoded_name = NULL;
 396         size_t encrypted_and_encoded_name_size;
 397         struct ecryptfs_mount_crypt_stat *mount_crypt_stat = NULL;
 398         struct dentry *lower_dir_dentry, *lower_dentry;
 399         int rc = 0;
 400
 401         lower_dir_dentry = ecryptfs_dentry_to_lower(ecryptfs_dentry->d_parent);
 402         mutex_lock(&d_inode(lower_dir_dentry)->i_mutex);
 403         lower_dentry = lookup_one_len(ecryptfs_dentry->d_name.name,
 404                                       lower_dir_dentry,
 405                                       ecryptfs_dentry->d_name.len);
 406         mutex_unlock(&d_inode(lower_dir_dentry)->i_mutex);
 407         if (IS_ERR(lower_dentry)) {
 408                 rc = PTR_ERR(lower_dentry);
 409                 ecryptfs_printk(KERN_DEBUG, "%s: lookup_one_len() returned "
 410                                 "[%d] on lower_dentry = [%pd]\n", __func__, rc,
 411                                 ecryptfs_dentry);
 412                 goto out;
 413         }
 414         if (d_really_is_positive(lower_dentry))
 415                 goto interpose;
 416         mount_crypt_stat = &ecryptfs_superblock_to_private(
 417                                 ecryptfs_dentry->d_sb)->mount_crypt_stat;
 418         if (!(mount_crypt_stat
 419             && (mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES)))
 420                 goto interpose;
 421         dput(lower_dentry);
 422         rc = ecryptfs_encrypt_and_encode_filename(
 423                 &encrypted_and_encoded_name, &encrypted_and_encoded_name_size,
 424                 NULL, mount_crypt_stat, ecryptfs_dentry->d_name.name,
 425                 ecryptfs_dentry->d_name.len);
 426         if (rc) {
 427                 printk(KERN_ERR "%s: Error attempting to encrypt and encode "
 428                        "filename; rc = [%d]\n", __func__, rc);
 429                 goto out;
 430         }
 431         mutex_lock(&d_inode(lower_dir_dentry)->i_mutex);
 432         lower_dentry = lookup_one_len(encrypted_and_encoded_name,
 433                                       lower_dir_dentry,
 434                                       encrypted_and_encoded_name_size);
 435         mutex_unlock(&d_inode(lower_dir_dentry)->i_mutex);
 436         if (IS_ERR(lower_dentry)) {
 437                 rc = PTR_ERR(lower_dentry);
 438                 ecryptfs_printk(KERN_DEBUG, "%s: lookup_one_len() returned "
 439                                 "[%d] on lower_dentry = [%s]\n", __func__, rc,
 440                                 encrypted_and_encoded_name);
 441                 goto out;
 442         }
 443 interpose:
 444         rc = ecryptfs_lookup_interpose(ecryptfs_dentry, lower_dentry,
 445                                        ecryptfs_dir_inode);
 446 out:
 447         kfree(encrypted_and_encoded_name);
 448         return ERR_PTR(rc);
 449 }
 450
 451 static int ecryptfs_link(struct dentry *old_dentry, struct inode *dir,
 452                          struct dentry *new_dentry)
 453 {
 454         struct dentry *lower_old_dentry;
 455         struct dentry *lower_new_dentry;
 456         struct dentry *lower_dir_dentry;
 457         u64 file_size_save;
 458         int rc;
 459
 460         file_size_save = i_size_read(d_inode(old_dentry));
 461         lower_old_dentry = ecryptfs_dentry_to_lower(old_dentry);
 462         lower_new_dentry = ecryptfs_dentry_to_lower(new_dentry);
 463         dget(lower_old_dentry);
 464         dget(lower_new_dentry);
 465         lower_dir_dentry = lock_parent(lower_new_dentry);
 466         rc = vfs_link(lower_old_dentry, d_inode(lower_dir_dentry),
 467                       lower_new_dentry, NULL);
 468         if (rc || d_really_is_negative(lower_new_dentry))
 469                 goto out_lock;
 470         rc = ecryptfs_interpose(lower_new_dentry, new_dentry, dir->i_sb);
 471         if (rc)
 472                 goto out_lock;
 473         fsstack_copy_attr_times(dir, d_inode(lower_dir_dentry));
 474         fsstack_copy_inode_size(dir, d_inode(lower_dir_dentry));
 475         set_nlink(d_inode(old_dentry),
 476                   ecryptfs_inode_to_lower(d_inode(old_dentry))->i_nlink);
 477         i_size_write(d_inode(new_dentry), file_size_save);
 478 out_lock:
 479         unlock_dir(lower_dir_dentry);
 480         dput(lower_new_dentry);
 481         dput(lower_old_dentry);
 482         return rc;
 483 }
 484
 485 static int ecryptfs_unlink(struct inode *dir, struct dentry *dentry)
 486 {
 487         return ecryptfs_do_unlink(dir, dentry, d_inode(dentry));
 488 }
 489
 490 static int ecryptfs_symlink(struct inode *dir, struct dentry *dentry,
 491                             const char *symname)
 492 {
 493         int rc;
 494         struct dentry *lower_dentry;
 495         struct dentry *lower_dir_dentry;
 496         char *encoded_symname;
 497         size_t encoded_symlen;
 498         struct ecryptfs_mount_crypt_stat *mount_crypt_stat = NULL;
 499
 500         lower_dentry = ecryptfs_dentry_to_lower(dentry);
 501         dget(lower_dentry);
 502         lower_dir_dentry = lock_parent(lower_dentry);
 503         mount_crypt_stat = &ecryptfs_superblock_to_private(
 504                 dir->i_sb)->mount_crypt_stat;
 505         rc = ecryptfs_encrypt_and_encode_filename(&encoded_symname,
 506                                                   &encoded_symlen,
 507                                                   NULL,
 508                                                   mount_crypt_stat, symname,
 509                                                   strlen(symname));
 510         if (rc)
 511                 goto out_lock;
 512         rc = vfs_symlink(d_inode(lower_dir_dentry), lower_dentry,
 513                          encoded_symname);
 514         kfree(encoded_symname);
 515         if (rc || d_really_is_negative(lower_dentry))
 516                 goto out_lock;
 517         rc = ecryptfs_interpose(lower_dentry, dentry, dir->i_sb);
 518         if (rc)
 519                 goto out_lock;
 520         fsstack_copy_attr_times(dir, d_inode(lower_dir_dentry));
 521         fsstack_copy_inode_size(dir, d_inode(lower_dir_dentry));
 522 out_lock:
 523         unlock_dir(lower_dir_dentry);
 524         dput(lower_dentry);
 525         if (d_really_is_negative(dentry))
 526                 d_drop(dentry);
 527         return rc;
 528 }
 529
 530 static int ecryptfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
 531 {
 532         int rc;
 533         struct dentry *lower_dentry;
 534         struct dentry *lower_dir_dentry;
 535
 536         lower_dentry = ecryptfs_dentry_to_lower(dentry);
 537         lower_dir_dentry = lock_parent(lower_dentry);
 538         rc = vfs_mkdir(d_inode(lower_dir_dentry), lower_dentry, mode);
 539         if (rc || d_really_is_negative(lower_dentry))
 540                 goto out;
 541         rc = ecryptfs_interpose(lower_dentry, dentry, dir->i_sb);
 542         if (rc)
 543                 goto out;
 544         fsstack_copy_attr_times(dir, d_inode(lower_dir_dentry));
 545         fsstack_copy_inode_size(dir, d_inode(lower_dir_dentry));
 546         set_nlink(dir, d_inode(lower_dir_dentry)->i_nlink);
 547 out:
 548         unlock_dir(lower_dir_dentry);
 549         if (d_really_is_negative(dentry))
 550                 d_drop(dentry);
 551         return rc;
 552 }
 553
 554 static int ecryptfs_rmdir(struct inode *dir, struct dentry *dentry)
 555 {
 556         struct dentry *lower_dentry;
 557         struct dentry *lower_dir_dentry;
 558         int rc;
 559
 560         lower_dentry = ecryptfs_dentry_to_lower(dentry);
 561         dget(dentry);
 562         lower_dir_dentry = lock_parent(lower_dentry);
 563         dget(lower_dentry);
 564         rc = vfs_rmdir(d_inode(lower_dir_dentry), lower_dentry);
 565         dput(lower_dentry);
 566         if (!rc && d_really_is_positive(dentry))
 567                 clear_nlink(d_inode(dentry));
 568         fsstack_copy_attr_times(dir, d_inode(lower_dir_dentry));
 569         set_nlink(dir, d_inode(lower_dir_dentry)->i_nlink);
 570         unlock_dir(lower_dir_dentry);
 571         if (!rc)
 572                 d_drop(dentry);
 573         dput(dentry);
 574         return rc;
 575 }
 576
 577 static int
 578 ecryptfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev)
 579 {
 580         int rc;
 581         struct dentry *lower_dentry;
 582         struct dentry *lower_dir_dentry;
 583
 584         lower_dentry = ecryptfs_dentry_to_lower(dentry);
 585         lower_dir_dentry = lock_parent(lower_dentry);
 586         rc = vfs_mknod(d_inode(lower_dir_dentry), lower_dentry, mode, dev);
 587         if (rc || d_really_is_negative(lower_dentry))
 588                 goto out;
 589         rc = ecryptfs_interpose(lower_dentry, dentry, dir->i_sb);
 590         if (rc)
 591                 goto out;
 592         fsstack_copy_attr_times(dir, d_inode(lower_dir_dentry));
 593         fsstack_copy_inode_size(dir, d_inode(lower_dir_dentry));
 594 out:
 595         unlock_dir(lower_dir_dentry);
 596         if (d_really_is_negative(dentry))
 597                 d_drop(dentry);
 598         return rc;
 599 }
 600
 601 static int
 602 ecryptfs_rename(struct inode *old_dir, struct dentry *old_dentry,
 603                 struct inode *new_dir, struct dentry *new_dentry)
 604 {
 605         int rc;
 606         struct dentry *lower_old_dentry;
 607         struct dentry *lower_new_dentry;
 608         struct dentry *lower_old_dir_dentry;
 609         struct dentry *lower_new_dir_dentry;
 610         struct dentry *trap = NULL;
 611         struct inode *target_inode;
 612
 613         lower_old_dentry = ecryptfs_dentry_to_lower(old_dentry);
 614         lower_new_dentry = ecryptfs_dentry_to_lower(new_dentry);
 615         dget(lower_old_dentry);
 616         dget(lower_new_dentry);
 617         lower_old_dir_dentry = dget_parent(lower_old_dentry);
 618         lower_new_dir_dentry = dget_parent(lower_new_dentry);
 619         target_inode = d_inode(new_dentry);
 620         trap = lock_rename(lower_old_dir_dentry, lower_new_dir_dentry);
 621         /* source should not be ancestor of target */
 622         if (trap == lower_old_dentry) {
 623                 rc = -EINVAL;
 624                 goto out_lock;
 625         }
 626         /* target should not be ancestor of source */
 627         if (trap == lower_new_dentry) {
 628                 rc = -ENOTEMPTY;
 629                 goto out_lock;
 630         }
 631         rc = vfs_rename(d_inode(lower_old_dir_dentry), lower_old_dentry,
 632                         d_inode(lower_new_dir_dentry), lower_new_dentry,
 633                         NULL, 0);
 634         if (rc)
 635                 goto out_lock;
 636         if (target_inode)
 637                 fsstack_copy_attr_all(target_inode,
 638                                       ecryptfs_inode_to_lower(target_inode));
 639         fsstack_copy_attr_all(new_dir, d_inode(lower_new_dir_dentry));
 640         if (new_dir != old_dir)
 641                 fsstack_copy_attr_all(old_dir, d_inode(lower_old_dir_dentry));
 642 out_lock:
 643         unlock_rename(lower_old_dir_dentry, lower_new_dir_dentry);
 644         dput(lower_new_dir_dentry);
 645         dput(lower_old_dir_dentry);
 646         dput(lower_new_dentry);
 647         dput(lower_old_dentry);
 648         return rc;
 649 }
 650
 651 static char *ecryptfs_readlink_lower(struct dentry *dentry, size_t *bufsiz)
 652 {
 653         struct dentry *lower_dentry = ecryptfs_dentry_to_lower(dentry);
 654         char *lower_buf;
 655         char *buf;
 656         mm_segment_t old_fs;
 657         int rc;
 658
 659         lower_buf = kmalloc(PATH_MAX, GFP_KERNEL);
 660         if (!lower_buf)
 661                 return ERR_PTR(-ENOMEM);
 662         old_fs = get_fs();
 663         set_fs(get_ds());
 664         rc = d_inode(lower_dentry)->i_op->readlink(lower_dentry,
 665                                                    (char __user *)lower_buf,
 666                                                    PATH_MAX);
 667         set_fs(old_fs);
 668         if (rc < 0)
 669                 goto out;
 670         rc = ecryptfs_decode_and_decrypt_filename(&buf, bufsiz, dentry->d_sb,
 671                                                   lower_buf, rc);
 672 out:
 673         kfree(lower_buf);
 674         return rc ? ERR_PTR(rc) : buf;
 675 }
 676
 677 static const char *ecryptfs_get_link(struct dentry *dentry,
 678                                      struct inode *inode,
 679                                      struct delayed_call *done)
 680 {
 681         size_t len;
 682         char *buf;
 683
 684         if (!dentry)
 685                 return ERR_PTR(-ECHILD);
 686
 687         buf = ecryptfs_readlink_lower(dentry, &len);
 688         if (IS_ERR(buf))
 689                 return buf;
 690         fsstack_copy_attr_atime(d_inode(dentry),
 691                                 d_inode(ecryptfs_dentry_to_lower(dentry)));
 692         buf[len] = '\0';
 693         set_delayed_call(done, kfree_link, buf);
 694         return buf;
 695 }
 696
 697 /**
 698  * upper_size_to_lower_size
 699  * @crypt_stat: Crypt_stat associated with file
 700  * @upper_size: Size of the upper file
 701  *
 702  * Calculate the required size of the lower file based on the
 703  * specified size of the upper file. This calculation is based on the
 704  * number of headers in the underlying file and the extent size.
 705  *
 706  * Returns Calculated size of the lower file.
 707  */
 708 static loff_t
 709 upper_size_to_lower_size(struct ecryptfs_crypt_stat *crypt_stat,
 710                          loff_t upper_size)
 711 {
 712         loff_t lower_size;
 713
 714         lower_size = ecryptfs_lower_header_size(crypt_stat);
 715         if (upper_size != 0) {
 716                 loff_t num_extents;
 717
 718                 num_extents = upper_size >> crypt_stat->extent_shift;
 719                 if (upper_size & ~crypt_stat->extent_mask)
 720                         num_extents++;
 721                 lower_size += (num_extents * crypt_stat->extent_size);
 722         }
 723         return lower_size;
 724 }
 725
 726 /**
 727  * truncate_upper
 728  * @dentry: The ecryptfs layer dentry
 729  * @ia: Address of the ecryptfs inode's attributes
 730  * @lower_ia: Address of the lower inode's attributes
 731  *
 732  * Function to handle truncations modifying the size of the file. Note
 733  * that the file sizes are interpolated. When expanding, we are simply
 734  * writing strings of 0's out. When truncating, we truncate the upper
 735  * inode and update the lower_ia according to the page index
 736  * interpolations. If ATTR_SIZE is set in lower_ia->ia_valid upon return,
 737  * the caller must use lower_ia in a call to notify_change() to perform
 738  * the truncation of the lower inode.
 739  *
 740  * Returns zero on success; non-zero otherwise
 741  */
 742 static int truncate_upper(struct dentry *dentry, struct iattr *ia,
 743                           struct iattr *lower_ia)
 744 {
 745         int rc = 0;
 746         struct inode *inode = d_inode(dentry);
 747         struct ecryptfs_crypt_stat *crypt_stat;
 748         loff_t i_size = i_size_read(inode);
 749         loff_t lower_size_before_truncate;
 750         loff_t lower_size_after_truncate;
 751
 752         if (unlikely((ia->ia_size == i_size))) {
 753                 lower_ia->ia_valid &= ~ATTR_SIZE;
 754                 return 0;
 755         }
 756         rc = ecryptfs_get_lower_file(dentry, inode);
 757         if (rc)
 758                 return rc;
 759         crypt_stat = &ecryptfs_inode_to_private(d_inode(dentry))->crypt_stat;
 760         /* Switch on growing or shrinking file */
 761         if (ia->ia_size > i_size) {
 762                 char zero[] = { 0x00 };
 763
 764                 lower_ia->ia_valid &= ~ATTR_SIZE;
 765                 /* Write a single 0 at the last position of the file;
 766                  * this triggers code that will fill in 0's throughout
 767                  * the intermediate portion of the previous end of the
 768                  * file and the new and of the file */
 769                 rc = ecryptfs_write(inode, zero,
 770                                     (ia->ia_size - 1), 1);
 771         } else { /* ia->ia_size < i_size_read(inode) */
 772                 /* We're chopping off all the pages down to the page
 773                  * in which ia->ia_size is located. Fill in the end of
 774                  * that page from (ia->ia_size & ~PAGE_CACHE_MASK) to
 775                  * PAGE_CACHE_SIZE with zeros. */
 776                 size_t num_zeros = (PAGE_CACHE_SIZE
 777                                     - (ia->ia_size & ~PAGE_CACHE_MASK));
 778
 779                 if (!(crypt_stat->flags & ECRYPTFS_ENCRYPTED)) {
 780                         truncate_setsize(inode, ia->ia_size);
 781                         lower_ia->ia_size = ia->ia_size;
 782                         lower_ia->ia_valid |= ATTR_SIZE;
 783                         goto out;
 784                 }
 785                 if (num_zeros) {
 786                         char *zeros_virt;
 787
 788                         zeros_virt = kzalloc(num_zeros, GFP_KERNEL);
 789                         if (!zeros_virt) {
 790                                 rc = -ENOMEM;
 791                                 goto out;
 792                         }
 793                         rc = ecryptfs_write(inode, zeros_virt,
 794                                             ia->ia_size, num_zeros);
 795                         kfree(zeros_virt);
 796                         if (rc) {
 797                                 printk(KERN_ERR "Error attempting to zero out "
 798                                        "the remainder of the end page on "
 799                                        "reducing truncate; rc = [%d]\n", rc);
 800                                 goto out;
 801                         }
 802                 }
 803                 truncate_setsize(inode, ia->ia_size);
 804                 rc = ecryptfs_write_inode_size_to_metadata(inode);
 805                 if (rc) {
 806                         printk(KERN_ERR "Problem with "
 807                                "ecryptfs_write_inode_size_to_metadata; "
 808                                "rc = [%d]\n", rc);
 809                         goto out;
 810                 }
 811                 /* We are reducing the size of the ecryptfs file, and need to
 812                  * know if we need to reduce the size of the lower file. */
 813                 lower_size_before_truncate =
 814                     upper_size_to_lower_size(crypt_stat, i_size);
 815                 lower_size_after_truncate =
 816                     upper_size_to_lower_size(crypt_stat, ia->ia_size);
 817                 if (lower_size_after_truncate < lower_size_before_truncate) {
 818                         lower_ia->ia_size = lower_size_after_truncate;
 819                         lower_ia->ia_valid |= ATTR_SIZE;
 820                 } else
 821                         lower_ia->ia_valid &= ~ATTR_SIZE;
 822         }
 823 out:
 824         ecryptfs_put_lower_file(inode);
 825         return rc;
 826 }
 827
 828 static int ecryptfs_inode_newsize_ok(struct inode *inode, loff_t offset)
 829 {
 830         struct ecryptfs_crypt_stat *crypt_stat;
 831         loff_t lower_oldsize, lower_newsize;
 832
 833         crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat;
 834         lower_oldsize = upper_size_to_lower_size(crypt_stat,
 835                                                  i_size_read(inode));
 836         lower_newsize = upper_size_to_lower_size(crypt_stat, offset);
 837         if (lower_newsize > lower_oldsize) {
 838                 /*
 839                  * The eCryptfs inode and the new *lower* size are mixed here
 840                  * because we may not have the lower i_mutex held and/or it may
 841                  * not be appropriate to call inode_newsize_ok() with inodes
 842                  * from other filesystems.
 843                  */
 844                 return inode_newsize_ok(inode, lower_newsize);
 845         }
 846
 847         return 0;
 848 }
 849
 850 /**
 851  * ecryptfs_truncate
 852  * @dentry: The ecryptfs layer dentry
 853  * @new_length: The length to expand the file to
 854  *
 855  * Simple function that handles the truncation of an eCryptfs inode and
 856  * its corresponding lower inode.
 857  *
 858  * Returns zero on success; non-zero otherwise
 859  */
 860 int ecryptfs_truncate(struct dentry *dentry, loff_t new_length)
 861 {
 862         struct iattr ia = { .ia_valid = ATTR_SIZE, .ia_size = new_length };
 863         struct iattr lower_ia = { .ia_valid = 0 };
 864         int rc;
 865
 866         rc = ecryptfs_inode_newsize_ok(d_inode(dentry), new_length);
 867         if (rc)
 868                 return rc;
 869
 870         rc = truncate_upper(dentry, &ia, &lower_ia);
 871         if (!rc && lower_ia.ia_valid & ATTR_SIZE) {
 872                 struct dentry *lower_dentry = ecryptfs_dentry_to_lower(dentry);
 873
 874                 mutex_lock(&d_inode(lower_dentry)->i_mutex);
 875                 rc = notify_change(lower_dentry, &lower_ia, NULL);
 876                 mutex_unlock(&d_inode(lower_dentry)->i_mutex);
 877         }
 878         return rc;
 879 }
 880
 881 static int
 882 ecryptfs_permission(struct inode *inode, int mask)
 883 {
 884         return inode_permission(ecryptfs_inode_to_lower(inode), mask);
 885 }
 886
 887 /**
 888  * ecryptfs_setattr
 889  * @dentry: dentry handle to the inode to modify
 890  * @ia: Structure with flags of what to change and values
 891  *
 892  * Updates the metadata of an inode. If the update is to the size
 893  * i.e. truncation, then ecryptfs_truncate will handle the size modification
 894  * of both the ecryptfs inode and the lower inode.
 895  *
 896  * All other metadata changes will be passed right to the lower filesystem,
 897  * and we will just update our inode to look like the lower.
 898  */
 899 static int ecryptfs_setattr(struct dentry *dentry, struct iattr *ia)
 900 {
 901         int rc = 0;
 902         struct dentry *lower_dentry;
 903         struct iattr lower_ia;
 904         struct inode *inode;
 905         struct inode *lower_inode;
 906         struct ecryptfs_crypt_stat *crypt_stat;
 907
 908         crypt_stat = &ecryptfs_inode_to_private(d_inode(dentry))->crypt_stat;
 909         if (!(crypt_stat->flags & ECRYPTFS_STRUCT_INITIALIZED))
 910                 ecryptfs_init_crypt_stat(crypt_stat);
 911         inode = d_inode(dentry);
 912         lower_inode = ecryptfs_inode_to_lower(inode);
 913         lower_dentry = ecryptfs_dentry_to_lower(dentry);
 914         mutex_lock(&crypt_stat->cs_mutex);
 915         if (d_is_dir(dentry))
 916                 crypt_stat->flags &= ~(ECRYPTFS_ENCRYPTED);
 917         else if (d_is_reg(dentry)
 918                  && (!(crypt_stat->flags & ECRYPTFS_POLICY_APPLIED)
 919                      || !(crypt_stat->flags & ECRYPTFS_KEY_VALID))) {
 920                 struct ecryptfs_mount_crypt_stat *mount_crypt_stat;
 921
 922                 mount_crypt_stat = &ecryptfs_superblock_to_private(
 923                         dentry->d_sb)->mount_crypt_stat;
 924                 rc = ecryptfs_get_lower_file(dentry, inode);
 925                 if (rc) {
 926                         mutex_unlock(&crypt_stat->cs_mutex);
 927                         goto out;
 928                 }
 929                 rc = ecryptfs_read_metadata(dentry);
 930                 ecryptfs_put_lower_file(inode);
 931                 if (rc) {
 932                         if (!(mount_crypt_stat->flags
 933                               & ECRYPTFS_PLAINTEXT_PASSTHROUGH_ENABLED)) {
 934                                 rc = -EIO;
 935                                 printk(KERN_WARNING "Either the lower file "
 936                                        "is not in a valid eCryptfs format, "
 937                                        "or the key could not be retrieved. "
 938                                        "Plaintext passthrough mode is not "
 939                                        "enabled; returning -EIO\n");
 940                                 mutex_unlock(&crypt_stat->cs_mutex);
 941                                 goto out;
 942                         }
 943                         rc = 0;
 944                         crypt_stat->flags &= ~(ECRYPTFS_I_SIZE_INITIALIZED
 945                                                | ECRYPTFS_ENCRYPTED);
 946                 }
 947         }
 948         mutex_unlock(&crypt_stat->cs_mutex);
 949
 950         rc = inode_change_ok(inode, ia);
 951         if (rc)
 952                 goto out;
 953         if (ia->ia_valid & ATTR_SIZE) {
 954                 rc = ecryptfs_inode_newsize_ok(inode, ia->ia_size);
 955                 if (rc)
 956                         goto out;
 957         }
 958
 959         memcpy(&lower_ia, ia, sizeof(lower_ia));
 960         if (ia->ia_valid & ATTR_FILE)
 961                 lower_ia.ia_file = ecryptfs_file_to_lower(ia->ia_file);
 962         if (ia->ia_valid & ATTR_SIZE) {
 963                 rc = truncate_upper(dentry, ia, &lower_ia);
 964                 if (rc < 0)
 965                         goto out;
 966         }
 967
 968         /*
 969          * mode change is for clearing setuid/setgid bits. Allow lower fs
 970          * to interpret this in its own way.
 971          */
 972         if (lower_ia.ia_valid & (ATTR_KILL_SUID | ATTR_KILL_SGID))
 973                 lower_ia.ia_valid &= ~ATTR_MODE;
 974
 975         mutex_lock(&d_inode(lower_dentry)->i_mutex);
 976         rc = notify_change(lower_dentry, &lower_ia, NULL);
 977         mutex_unlock(&d_inode(lower_dentry)->i_mutex);
 978 out:
 979         fsstack_copy_attr_all(inode, lower_inode);
 980         return rc;
 981 }
 982
 983 static int ecryptfs_getattr_link(struct vfsmount *mnt, struct dentry *dentry,
 984                                  struct kstat *stat)
 985 {
 986         struct ecryptfs_mount_crypt_stat *mount_crypt_stat;
 987         int rc = 0;
 988
 989         mount_crypt_stat = &ecryptfs_superblock_to_private(
 990                                                 dentry->d_sb)->mount_crypt_stat;
 991         generic_fillattr(d_inode(dentry), stat);
 992         if (mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES) {
 993                 char *target;
 994                 size_t targetsiz;
 995
 996                 target = ecryptfs_readlink_lower(dentry, &targetsiz);
 997                 if (!IS_ERR(target)) {
 998                         kfree(target);
 999                         stat->size = targetsiz;
1000                 } else {
1001                         rc = PTR_ERR(target);
1002                 }
1003         }
1004         return rc;
1005 }
1006
1007 static int ecryptfs_getattr(struct vfsmount *mnt, struct dentry *dentry,
1008                             struct kstat *stat)
1009 {
1010         struct kstat lower_stat;
1011         int rc;
1012
1013         rc = vfs_getattr(ecryptfs_dentry_to_lower_path(dentry), &lower_stat);
1014         if (!rc) {
1015                 fsstack_copy_attr_all(d_inode(dentry),
1016                                       ecryptfs_inode_to_lower(d_inode(dentry)));
1017                 generic_fillattr(d_inode(dentry), stat);
1018                 stat->blocks = lower_stat.blocks;
1019         }
1020         return rc;
1021 }
1022
1023 int
1024 ecryptfs_setxattr(struct dentry *dentry, const char *name, const void *value,
1025                   size_t size, int flags)
1026 {
1027         int rc = 0;
1028         struct dentry *lower_dentry;
1029
1030         lower_dentry = ecryptfs_dentry_to_lower(dentry);
1031         if (!d_inode(lower_dentry)->i_op->setxattr) {
1032                 rc = -EOPNOTSUPP;
1033                 goto out;
1034         }
1035
1036         rc = vfs_setxattr(lower_dentry, name, value, size, flags);
1037         if (!rc && d_really_is_positive(dentry))
1038                 fsstack_copy_attr_all(d_inode(dentry), d_inode(lower_dentry));
1039 out:
1040         return rc;
1041 }
1042
1043 ssize_t
1044 ecryptfs_getxattr_lower(struct dentry *lower_dentry, const char *name,
1045                         void *value, size_t size)
1046 {
1047         int rc = 0;
1048
1049         if (!d_inode(lower_dentry)->i_op->getxattr) {
1050                 rc = -EOPNOTSUPP;
1051                 goto out;
1052         }
1053         mutex_lock(&d_inode(lower_dentry)->i_mutex);
1054         rc = d_inode(lower_dentry)->i_op->getxattr(lower_dentry, name, value,
1055                                                    size);
1056         mutex_unlock(&d_inode(lower_dentry)->i_mutex);
1057 out:
1058         return rc;
1059 }
1060
1061 static ssize_t
1062 ecryptfs_getxattr(struct dentry *dentry, const char *name, void *value,
1063                   size_t size)
1064 {
1065         return ecryptfs_getxattr_lower(ecryptfs_dentry_to_lower(dentry), name,
1066                                        value, size);
1067 }
1068
1069 static ssize_t
1070 ecryptfs_listxattr(struct dentry *dentry, char *list, size_t size)
1071 {
1072         int rc = 0;
1073         struct dentry *lower_dentry;
1074
1075         lower_dentry = ecryptfs_dentry_to_lower(dentry);
1076         if (!d_inode(lower_dentry)->i_op->listxattr) {
1077                 rc = -EOPNOTSUPP;
1078                 goto out;
1079         }
1080         mutex_lock(&d_inode(lower_dentry)->i_mutex);
1081         rc = d_inode(lower_dentry)->i_op->listxattr(lower_dentry, list, size);
1082         mutex_unlock(&d_inode(lower_dentry)->i_mutex);
1083 out:
1084         return rc;
1085 }
1086
1087 static int ecryptfs_removexattr(struct dentry *dentry, const char *name)
1088 {
1089         int rc = 0;
1090         struct dentry *lower_dentry;
1091
1092         lower_dentry = ecryptfs_dentry_to_lower(dentry);
1093         if (!d_inode(lower_dentry)->i_op->removexattr) {
1094                 rc = -EOPNOTSUPP;
1095                 goto out;
1096         }
1097         mutex_lock(&d_inode(lower_dentry)->i_mutex);
1098         rc = d_inode(lower_dentry)->i_op->removexattr(lower_dentry, name);
1099         mutex_unlock(&d_inode(lower_dentry)->i_mutex);
1100 out:
1101         return rc;
1102 }
1103
1104 const struct inode_operations ecryptfs_symlink_iops = {
1105         .readlink = generic_readlink,
1106         .get_link = ecryptfs_get_link,
1107         .permission = ecryptfs_permission,
1108         .setattr = ecryptfs_setattr,
1109         .getattr = ecryptfs_getattr_link,
1110         .setxattr = ecryptfs_setxattr,
1111         .getxattr = ecryptfs_getxattr,
1112         .listxattr = ecryptfs_listxattr,
1113         .removexattr = ecryptfs_removexattr
1114 };
1115
1116 const struct inode_operations ecryptfs_dir_iops = {
1117         .create = ecryptfs_create,
1118         .lookup = ecryptfs_lookup,
1119         .link = ecryptfs_link,
1120         .unlink = ecryptfs_unlink,
1121         .symlink = ecryptfs_symlink,
1122         .mkdir = ecryptfs_mkdir,
1123         .rmdir = ecryptfs_rmdir,
1124         .mknod = ecryptfs_mknod,
1125         .rename = ecryptfs_rename,
1126         .permission = ecryptfs_permission,
1127         .setattr = ecryptfs_setattr,
1128         .setxattr = ecryptfs_setxattr,
1129         .getxattr = ecryptfs_getxattr,
1130         .listxattr = ecryptfs_listxattr,
1131         .removexattr = ecryptfs_removexattr
1132 };
1133
1134 const struct inode_operations ecryptfs_main_iops = {
1135         .permission = ecryptfs_permission,
1136         .setattr = ecryptfs_setattr,
1137         .getattr = ecryptfs_getattr,
1138         .setxattr = ecryptfs_setxattr,
1139         .getxattr = ecryptfs_getxattr,
1140         .listxattr = ecryptfs_listxattr,
1141         .removexattr = ecryptfs_removexattr
1142 };