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 <asm/unaligned.h>
  35 #include "ecryptfs_kernel.h"
  36
  37 static struct dentry *lock_parent(struct dentry *dentry)
  38 {
  39         struct dentry *dir;
  40
  41         dir = dget_parent(dentry);
  42         mutex_lock_nested(&(dir->d_inode->i_mutex), I_MUTEX_PARENT);
  43         return dir;
  44 }
  45
  46 static void unlock_dir(struct dentry *dir)
  47 {
  48         mutex_unlock(&dir->d_inode->i_mutex);
  49         dput(dir);
  50 }
  51
  52 /**
  53  * ecryptfs_create_underlying_file
  54  * @lower_dir_inode: inode of the parent in the lower fs of the new file
  55  * @dentry: New file's dentry
  56  * @mode: The mode of the new file
  57  * @nd: nameidata of ecryptfs' parent's dentry & vfsmount
  58  *
  59  * Creates the file in the lower file system.
  60  *
  61  * Returns zero on success; non-zero on error condition
  62  */
  63 static int
  64 ecryptfs_create_underlying_file(struct inode *lower_dir_inode,
  65                                 struct dentry *dentry, int mode,
  66                                 struct nameidata *nd)
  67 {
  68         struct dentry *lower_dentry = ecryptfs_dentry_to_lower(dentry);
  69         struct vfsmount *lower_mnt = ecryptfs_dentry_to_lower_mnt(dentry);
  70         struct dentry *dentry_save;
  71         struct vfsmount *vfsmount_save;
  72         int rc;
  73
  74         dentry_save = nd->path.dentry;
  75         vfsmount_save = nd->path.mnt;
  76         nd->path.dentry = lower_dentry;
  77         nd->path.mnt = lower_mnt;
  78         rc = vfs_create(lower_dir_inode, lower_dentry, mode, nd);
  79         nd->path.dentry = dentry_save;
  80         nd->path.mnt = vfsmount_save;
  81         return rc;
  82 }
  83
  84 /**
  85  * ecryptfs_do_create
  86  * @directory_inode: inode of the new file's dentry's parent in ecryptfs
  87  * @ecryptfs_dentry: New file's dentry in ecryptfs
  88  * @mode: The mode of the new file
  89  * @nd: nameidata of ecryptfs' parent's dentry & vfsmount
  90  *
  91  * Creates the underlying file and the eCryptfs inode which will link to
  92  * it. It will also update the eCryptfs directory inode to mimic the
  93  * stat of the lower directory inode.
  94  *
  95  * Returns zero on success; non-zero on error condition
  96  */
  97 static int
  98 ecryptfs_do_create(struct inode *directory_inode,
  99                    struct dentry *ecryptfs_dentry, int mode,
 100                    struct nameidata *nd)
 101 {
 102         int rc;
 103         struct dentry *lower_dentry;
 104         struct dentry *lower_dir_dentry;
 105
 106         lower_dentry = ecryptfs_dentry_to_lower(ecryptfs_dentry);
 107         lower_dir_dentry = lock_parent(lower_dentry);
 108         if (IS_ERR(lower_dir_dentry)) {
 109                 ecryptfs_printk(KERN_ERR, "Error locking directory of "
 110                                 "dentry\n");
 111                 rc = PTR_ERR(lower_dir_dentry);
 112                 goto out;
 113         }
 114         rc = ecryptfs_create_underlying_file(lower_dir_dentry->d_inode,
 115                                              ecryptfs_dentry, mode, nd);
 116         if (rc) {
 117                 printk(KERN_ERR "%s: Failure to create dentry in lower fs; "
 118                        "rc = [%d]\n", __func__, rc);
 119                 goto out_lock;
 120         }
 121         rc = ecryptfs_interpose(lower_dentry, ecryptfs_dentry,
 122                                 directory_inode->i_sb, 0);
 123         if (rc) {
 124                 ecryptfs_printk(KERN_ERR, "Failure in ecryptfs_interpose\n");
 125                 goto out_lock;
 126         }
 127         fsstack_copy_attr_times(directory_inode, lower_dir_dentry->d_inode);
 128         fsstack_copy_inode_size(directory_inode, lower_dir_dentry->d_inode);
 129 out_lock:
 130         unlock_dir(lower_dir_dentry);
 131 out:
 132         return rc;
 133 }
 134
 135 /**
 136  * grow_file
 137  * @ecryptfs_dentry: the eCryptfs dentry
 138  *
 139  * This is the code which will grow the file to its correct size.
 140  */
 141 static int grow_file(struct dentry *ecryptfs_dentry)
 142 {
 143         struct inode *ecryptfs_inode = ecryptfs_dentry->d_inode;
 144         struct file fake_file;
 145         struct ecryptfs_file_info tmp_file_info;
 146         char zero_virt[] = { 0x00 };
 147         int rc = 0;
 148
 149         memset(&fake_file, 0, sizeof(fake_file));
 150         fake_file.f_path.dentry = ecryptfs_dentry;
 151         memset(&tmp_file_info, 0, sizeof(tmp_file_info));
 152         ecryptfs_set_file_private(&fake_file, &tmp_file_info);
 153         ecryptfs_set_file_lower(
 154                 &fake_file,
 155                 ecryptfs_inode_to_private(ecryptfs_inode)->lower_file);
 156         rc = ecryptfs_write(&fake_file, zero_virt, 0, 1);
 157         i_size_write(ecryptfs_inode, 0);
 158         rc = ecryptfs_write_inode_size_to_metadata(ecryptfs_inode);
 159         ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat.flags |=
 160                 ECRYPTFS_NEW_FILE;
 161         return rc;
 162 }
 163
 164 /**
 165  * ecryptfs_initialize_file
 166  *
 167  * Cause the file to be changed from a basic empty file to an ecryptfs
 168  * file with a header and first data page.
 169  *
 170  * Returns zero on success
 171  */
 172 static int ecryptfs_initialize_file(struct dentry *ecryptfs_dentry)
 173 {
 174         struct ecryptfs_crypt_stat *crypt_stat =
 175                 &ecryptfs_inode_to_private(ecryptfs_dentry->d_inode)->crypt_stat;
 176         int rc = 0;
 177
 178         if (S_ISDIR(ecryptfs_dentry->d_inode->i_mode)) {
 179                 ecryptfs_printk(KERN_DEBUG, "This is a directory\n");
 180                 crypt_stat->flags &= ~(ECRYPTFS_ENCRYPTED);
 181                 goto out;
 182         }
 183         crypt_stat->flags |= ECRYPTFS_NEW_FILE;
 184         ecryptfs_printk(KERN_DEBUG, "Initializing crypto context\n");
 185         rc = ecryptfs_new_file_context(ecryptfs_dentry);
 186         if (rc) {
 187                 ecryptfs_printk(KERN_ERR, "Error creating new file "
 188                                 "context; rc = [%d]\n", rc);
 189                 goto out;
 190         }
 191         if (!ecryptfs_inode_to_private(ecryptfs_dentry->d_inode)->lower_file) {
 192                 rc = ecryptfs_init_persistent_file(ecryptfs_dentry);
 193                 if (rc) {
 194                         printk(KERN_ERR "%s: Error attempting to initialize "
 195                                "the persistent file for the dentry with name "
 196                                "[%s]; rc = [%d]\n", __func__,
 197                                ecryptfs_dentry->d_name.name, rc);
 198                         goto out;
 199                 }
 200         }
 201         rc = ecryptfs_write_metadata(ecryptfs_dentry);
 202         if (rc) {
 203                 printk(KERN_ERR "Error writing headers; rc = [%d]\n", rc);
 204                 goto out;
 205         }
 206         rc = grow_file(ecryptfs_dentry);
 207         if (rc)
 208                 printk(KERN_ERR "Error growing file; rc = [%d]\n", rc);
 209 out:
 210         return rc;
 211 }
 212
 213 /**
 214  * ecryptfs_create
 215  * @dir: The inode of the directory in which to create the file.
 216  * @dentry: The eCryptfs dentry
 217  * @mode: The mode of the new file.
 218  * @nd: nameidata
 219  *
 220  * Creates a new file.
 221  *
 222  * Returns zero on success; non-zero on error condition
 223  */
 224 static int
 225 ecryptfs_create(struct inode *directory_inode, struct dentry *ecryptfs_dentry,
 226                 int mode, struct nameidata *nd)
 227 {
 228         int rc;
 229
 230         /* ecryptfs_do_create() calls ecryptfs_interpose() */
 231         rc = ecryptfs_do_create(directory_inode, ecryptfs_dentry, mode, nd);
 232         if (unlikely(rc)) {
 233                 ecryptfs_printk(KERN_WARNING, "Failed to create file in"
 234                                 "lower filesystem\n");
 235                 goto out;
 236         }
 237         /* At this point, a file exists on "disk"; we need to make sure
 238          * that this on disk file is prepared to be an ecryptfs file */
 239         rc = ecryptfs_initialize_file(ecryptfs_dentry);
 240 out:
 241         return rc;
 242 }
 243
 244 /**
 245  * ecryptfs_lookup_and_interpose_lower - Perform a lookup
 246  */
 247 int ecryptfs_lookup_and_interpose_lower(struct dentry *ecryptfs_dentry,
 248                                         struct dentry *lower_dentry,
 249                                         struct inode *ecryptfs_dir_inode,
 250                                         struct nameidata *ecryptfs_nd)
 251 {
 252         struct dentry *lower_dir_dentry;
 253         struct vfsmount *lower_mnt;
 254         struct inode *lower_inode;
 255         struct ecryptfs_mount_crypt_stat *mount_crypt_stat;
 256         struct ecryptfs_crypt_stat *crypt_stat;
 257         char *page_virt = NULL;
 258         u64 file_size;
 259         int rc = 0;
 260
 261         lower_dir_dentry = lower_dentry->d_parent;
 262         lower_mnt = mntget(ecryptfs_dentry_to_lower_mnt(
 263                                    ecryptfs_dentry->d_parent));
 264         lower_inode = lower_dentry->d_inode;
 265         fsstack_copy_attr_atime(ecryptfs_dir_inode, lower_dir_dentry->d_inode);
 266         BUG_ON(!atomic_read(&lower_dentry->d_count));
 267         ecryptfs_set_dentry_private(ecryptfs_dentry,
 268                                     kmem_cache_alloc(ecryptfs_dentry_info_cache,
 269                                                      GFP_KERNEL));
 270         if (!ecryptfs_dentry_to_private(ecryptfs_dentry)) {
 271                 rc = -ENOMEM;
 272                 printk(KERN_ERR "%s: Out of memory whilst attempting "
 273                        "to allocate ecryptfs_dentry_info struct\n",
 274                         __func__);
 275                 goto out_dput;
 276         }
 277         ecryptfs_set_dentry_lower(ecryptfs_dentry, lower_dentry);
 278         ecryptfs_set_dentry_lower_mnt(ecryptfs_dentry, lower_mnt);
 279         if (!lower_dentry->d_inode) {
 280                 /* We want to add because we couldn't find in lower */
 281                 d_add(ecryptfs_dentry, NULL);
 282                 goto out;
 283         }
 284         rc = ecryptfs_interpose(lower_dentry, ecryptfs_dentry,
 285                                 ecryptfs_dir_inode->i_sb, 1);
 286         if (rc) {
 287                 printk(KERN_ERR "%s: Error interposing; rc = [%d]\n",
 288                        __func__, rc);
 289                 goto out;
 290         }
 291         if (S_ISDIR(lower_inode->i_mode))
 292                 goto out;
 293         if (S_ISLNK(lower_inode->i_mode))
 294                 goto out;
 295         if (special_file(lower_inode->i_mode))
 296                 goto out;
 297         if (!ecryptfs_nd)
 298                 goto out;
 299         /* Released in this function */
 300         page_virt = kmem_cache_zalloc(ecryptfs_header_cache_2, GFP_USER);
 301         if (!page_virt) {
 302                 printk(KERN_ERR "%s: Cannot kmem_cache_zalloc() a page\n",
 303                        __func__);
 304                 rc = -ENOMEM;
 305                 goto out;
 306         }
 307         if (!ecryptfs_inode_to_private(ecryptfs_dentry->d_inode)->lower_file) {
 308                 rc = ecryptfs_init_persistent_file(ecryptfs_dentry);
 309                 if (rc) {
 310                         printk(KERN_ERR "%s: Error attempting to initialize "
 311                                "the persistent file for the dentry with name "
 312                                "[%s]; rc = [%d]\n", __func__,
 313                                ecryptfs_dentry->d_name.name, rc);
 314                         goto out_free_kmem;
 315                 }
 316         }
 317         crypt_stat = &ecryptfs_inode_to_private(
 318                                         ecryptfs_dentry->d_inode)->crypt_stat;
 319         /* TODO: lock for crypt_stat comparison */
 320         if (!(crypt_stat->flags & ECRYPTFS_POLICY_APPLIED))
 321                         ecryptfs_set_default_sizes(crypt_stat);
 322         rc = ecryptfs_read_and_validate_header_region(page_virt,
 323                                                       ecryptfs_dentry->d_inode);
 324         if (rc) {
 325                 rc = ecryptfs_read_and_validate_xattr_region(page_virt,
 326                                                              ecryptfs_dentry);
 327                 if (rc) {
 328                         rc = 0;
 329                         goto out_free_kmem;
 330                 }
 331                 crypt_stat->flags |= ECRYPTFS_METADATA_IN_XATTR;
 332         }
 333         mount_crypt_stat = &ecryptfs_superblock_to_private(
 334                 ecryptfs_dentry->d_sb)->mount_crypt_stat;
 335         if (mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED) {
 336                 if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR)
 337                         file_size = (crypt_stat->num_header_bytes_at_front
 338                                      + i_size_read(lower_dentry->d_inode));
 339                 else
 340                         file_size = i_size_read(lower_dentry->d_inode);
 341         } else {
 342                 file_size = get_unaligned_be64(page_virt);
 343         }
 344         i_size_write(ecryptfs_dentry->d_inode, (loff_t)file_size);
 345 out_free_kmem:
 346         kmem_cache_free(ecryptfs_header_cache_2, page_virt);
 347         goto out;
 348 out_dput:
 349         dput(lower_dentry);
 350         d_drop(ecryptfs_dentry);
 351 out:
 352         return rc;
 353 }
 354
 355 /**
 356  * ecryptfs_lookup
 357  * @ecryptfs_dir_inode: The eCryptfs directory inode
 358  * @ecryptfs_dentry: The eCryptfs dentry that we are looking up
 359  * @ecryptfs_nd: nameidata; may be NULL
 360  *
 361  * Find a file on disk. If the file does not exist, then we'll add it to the
 362  * dentry cache and continue on to read it from the disk.
 363  */
 364 static struct dentry *ecryptfs_lookup(struct inode *ecryptfs_dir_inode,
 365                                       struct dentry *ecryptfs_dentry,
 366                                       struct nameidata *ecryptfs_nd)
 367 {
 368         char *encrypted_and_encoded_name = NULL;
 369         size_t encrypted_and_encoded_name_size;
 370         struct ecryptfs_mount_crypt_stat *mount_crypt_stat = NULL;
 371         struct dentry *lower_dir_dentry, *lower_dentry;
 372         int rc = 0;
 373
 374         ecryptfs_dentry->d_op = &ecryptfs_dops;
 375         if ((ecryptfs_dentry->d_name.len == 1
 376              && !strcmp(ecryptfs_dentry->d_name.name, "."))
 377             || (ecryptfs_dentry->d_name.len == 2
 378                 && !strcmp(ecryptfs_dentry->d_name.name, ".."))) {
 379                 goto out_d_drop;
 380         }
 381         lower_dir_dentry = ecryptfs_dentry_to_lower(ecryptfs_dentry->d_parent);
 382         mutex_lock(&lower_dir_dentry->d_inode->i_mutex);
 383         lower_dentry = lookup_one_len(ecryptfs_dentry->d_name.name,
 384                                       lower_dir_dentry,
 385                                       ecryptfs_dentry->d_name.len);
 386         mutex_unlock(&lower_dir_dentry->d_inode->i_mutex);
 387         if (IS_ERR(lower_dentry)) {
 388                 rc = PTR_ERR(lower_dentry);
 389                 printk(KERN_ERR "%s: lookup_one_len() returned [%d] on "
 390                        "lower_dentry = [%s]\n", __func__, rc,
 391                        ecryptfs_dentry->d_name.name);
 392                 goto out_d_drop;
 393         }
 394         if (lower_dentry->d_inode)
 395                 goto lookup_and_interpose;
 396         mount_crypt_stat = &ecryptfs_superblock_to_private(
 397                                 ecryptfs_dentry->d_sb)->mount_crypt_stat;
 398         if (!(mount_crypt_stat
 399             && (mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES)))
 400                 goto lookup_and_interpose;
 401         dput(lower_dentry);
 402         rc = ecryptfs_encrypt_and_encode_filename(
 403                 &encrypted_and_encoded_name, &encrypted_and_encoded_name_size,
 404                 NULL, mount_crypt_stat, ecryptfs_dentry->d_name.name,
 405                 ecryptfs_dentry->d_name.len);
 406         if (rc) {
 407                 printk(KERN_ERR "%s: Error attempting to encrypt and encode "
 408                        "filename; rc = [%d]\n", __func__, rc);
 409                 goto out_d_drop;
 410         }
 411         mutex_lock(&lower_dir_dentry->d_inode->i_mutex);
 412         lower_dentry = lookup_one_len(encrypted_and_encoded_name,
 413                                       lower_dir_dentry,
 414                                       encrypted_and_encoded_name_size - 1);
 415         mutex_unlock(&lower_dir_dentry->d_inode->i_mutex);
 416         if (IS_ERR(lower_dentry)) {
 417                 rc = PTR_ERR(lower_dentry);
 418                 printk(KERN_ERR "%s: lookup_one_len() returned [%d] on "
 419                        "lower_dentry = [%s]\n", __func__, rc,
 420                        encrypted_and_encoded_name);
 421                 goto out_d_drop;
 422         }
 423 lookup_and_interpose:
 424         rc = ecryptfs_lookup_and_interpose_lower(ecryptfs_dentry, lower_dentry,
 425                                                  ecryptfs_dir_inode,
 426                                                  ecryptfs_nd);
 427         goto out;
 428 out_d_drop:
 429         d_drop(ecryptfs_dentry);
 430 out:
 431         kfree(encrypted_and_encoded_name);
 432         return ERR_PTR(rc);
 433 }
 434
 435 static int ecryptfs_link(struct dentry *old_dentry, struct inode *dir,
 436                          struct dentry *new_dentry)
 437 {
 438         struct dentry *lower_old_dentry;
 439         struct dentry *lower_new_dentry;
 440         struct dentry *lower_dir_dentry;
 441         u64 file_size_save;
 442         int rc;
 443
 444         file_size_save = i_size_read(old_dentry->d_inode);
 445         lower_old_dentry = ecryptfs_dentry_to_lower(old_dentry);
 446         lower_new_dentry = ecryptfs_dentry_to_lower(new_dentry);
 447         dget(lower_old_dentry);
 448         dget(lower_new_dentry);
 449         lower_dir_dentry = lock_parent(lower_new_dentry);
 450         rc = vfs_link(lower_old_dentry, lower_dir_dentry->d_inode,
 451                       lower_new_dentry);
 452         if (rc || !lower_new_dentry->d_inode)
 453                 goto out_lock;
 454         rc = ecryptfs_interpose(lower_new_dentry, new_dentry, dir->i_sb, 0);
 455         if (rc)
 456                 goto out_lock;
 457         fsstack_copy_attr_times(dir, lower_new_dentry->d_inode);
 458         fsstack_copy_inode_size(dir, lower_new_dentry->d_inode);
 459         old_dentry->d_inode->i_nlink =
 460                 ecryptfs_inode_to_lower(old_dentry->d_inode)->i_nlink;
 461         i_size_write(new_dentry->d_inode, file_size_save);
 462 out_lock:
 463         unlock_dir(lower_dir_dentry);
 464         dput(lower_new_dentry);
 465         dput(lower_old_dentry);
 466         d_drop(lower_old_dentry);
 467         d_drop(new_dentry);
 468         d_drop(old_dentry);
 469         return rc;
 470 }
 471
 472 static int ecryptfs_unlink(struct inode *dir, struct dentry *dentry)
 473 {
 474         int rc = 0;
 475         struct dentry *lower_dentry = ecryptfs_dentry_to_lower(dentry);
 476         struct inode *lower_dir_inode = ecryptfs_inode_to_lower(dir);
 477         struct dentry *lower_dir_dentry;
 478
 479         lower_dir_dentry = lock_parent(lower_dentry);
 480         rc = vfs_unlink(lower_dir_inode, lower_dentry);
 481         if (rc) {
 482                 printk(KERN_ERR "Error in vfs_unlink; rc = [%d]\n", rc);
 483                 goto out_unlock;
 484         }
 485         fsstack_copy_attr_times(dir, lower_dir_inode);
 486         dentry->d_inode->i_nlink =
 487                 ecryptfs_inode_to_lower(dentry->d_inode)->i_nlink;
 488         dentry->d_inode->i_ctime = dir->i_ctime;
 489         d_drop(dentry);
 490 out_unlock:
 491         unlock_dir(lower_dir_dentry);
 492         return rc;
 493 }
 494
 495 static int ecryptfs_symlink(struct inode *dir, struct dentry *dentry,
 496                             const char *symname)
 497 {
 498         int rc;
 499         struct dentry *lower_dentry;
 500         struct dentry *lower_dir_dentry;
 501         char *encoded_symname;
 502         size_t encoded_symlen;
 503         struct ecryptfs_mount_crypt_stat *mount_crypt_stat = NULL;
 504
 505         lower_dentry = ecryptfs_dentry_to_lower(dentry);
 506         dget(lower_dentry);
 507         lower_dir_dentry = lock_parent(lower_dentry);
 508         mount_crypt_stat = &ecryptfs_superblock_to_private(
 509                 dir->i_sb)->mount_crypt_stat;
 510         rc = ecryptfs_encrypt_and_encode_filename(&encoded_symname,
 511                                                   &encoded_symlen,
 512                                                   NULL,
 513                                                   mount_crypt_stat, symname,
 514                                                   strlen(symname));
 515         if (rc)
 516                 goto out_lock;
 517         rc = vfs_symlink(lower_dir_dentry->d_inode, lower_dentry,
 518                          encoded_symname);
 519         kfree(encoded_symname);
 520         if (rc || !lower_dentry->d_inode)
 521                 goto out_lock;
 522         rc = ecryptfs_interpose(lower_dentry, dentry, dir->i_sb, 0);
 523         if (rc)
 524                 goto out_lock;
 525         fsstack_copy_attr_times(dir, lower_dir_dentry->d_inode);
 526         fsstack_copy_inode_size(dir, lower_dir_dentry->d_inode);
 527 out_lock:
 528         unlock_dir(lower_dir_dentry);
 529         dput(lower_dentry);
 530         if (!dentry->d_inode)
 531                 d_drop(dentry);
 532         return rc;
 533 }
 534
 535 static int ecryptfs_mkdir(struct inode *dir, struct dentry *dentry, int mode)
 536 {
 537         int rc;
 538         struct dentry *lower_dentry;
 539         struct dentry *lower_dir_dentry;
 540
 541         lower_dentry = ecryptfs_dentry_to_lower(dentry);
 542         lower_dir_dentry = lock_parent(lower_dentry);
 543         rc = vfs_mkdir(lower_dir_dentry->d_inode, lower_dentry, mode);
 544         if (rc || !lower_dentry->d_inode)
 545                 goto out;
 546         rc = ecryptfs_interpose(lower_dentry, dentry, dir->i_sb, 0);
 547         if (rc)
 548                 goto out;
 549         fsstack_copy_attr_times(dir, lower_dir_dentry->d_inode);
 550         fsstack_copy_inode_size(dir, lower_dir_dentry->d_inode);
 551         dir->i_nlink = lower_dir_dentry->d_inode->i_nlink;
 552 out:
 553         unlock_dir(lower_dir_dentry);
 554         if (!dentry->d_inode)
 555                 d_drop(dentry);
 556         return rc;
 557 }
 558
 559 static int ecryptfs_rmdir(struct inode *dir, struct dentry *dentry)
 560 {
 561         struct dentry *lower_dentry;
 562         struct dentry *lower_dir_dentry;
 563         int rc;
 564
 565         lower_dentry = ecryptfs_dentry_to_lower(dentry);
 566         dget(dentry);
 567         lower_dir_dentry = lock_parent(lower_dentry);
 568         dget(lower_dentry);
 569         rc = vfs_rmdir(lower_dir_dentry->d_inode, lower_dentry);
 570         dput(lower_dentry);
 571         if (!rc)
 572                 d_delete(lower_dentry);
 573         fsstack_copy_attr_times(dir, lower_dir_dentry->d_inode);
 574         dir->i_nlink = lower_dir_dentry->d_inode->i_nlink;
 575         unlock_dir(lower_dir_dentry);
 576         if (!rc)
 577                 d_drop(dentry);
 578         dput(dentry);
 579         return rc;
 580 }
 581
 582 static int
 583 ecryptfs_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev)
 584 {
 585         int rc;
 586         struct dentry *lower_dentry;
 587         struct dentry *lower_dir_dentry;
 588
 589         lower_dentry = ecryptfs_dentry_to_lower(dentry);
 590         lower_dir_dentry = lock_parent(lower_dentry);
 591         rc = vfs_mknod(lower_dir_dentry->d_inode, lower_dentry, mode, dev);
 592         if (rc || !lower_dentry->d_inode)
 593                 goto out;
 594         rc = ecryptfs_interpose(lower_dentry, dentry, dir->i_sb, 0);
 595         if (rc)
 596                 goto out;
 597         fsstack_copy_attr_times(dir, lower_dir_dentry->d_inode);
 598         fsstack_copy_inode_size(dir, lower_dir_dentry->d_inode);
 599 out:
 600         unlock_dir(lower_dir_dentry);
 601         if (!dentry->d_inode)
 602                 d_drop(dentry);
 603         return rc;
 604 }
 605
 606 static int
 607 ecryptfs_rename(struct inode *old_dir, struct dentry *old_dentry,
 608                 struct inode *new_dir, struct dentry *new_dentry)
 609 {
 610         int rc;
 611         struct dentry *lower_old_dentry;
 612         struct dentry *lower_new_dentry;
 613         struct dentry *lower_old_dir_dentry;
 614         struct dentry *lower_new_dir_dentry;
 615
 616         lower_old_dentry = ecryptfs_dentry_to_lower(old_dentry);
 617         lower_new_dentry = ecryptfs_dentry_to_lower(new_dentry);
 618         dget(lower_old_dentry);
 619         dget(lower_new_dentry);
 620         lower_old_dir_dentry = dget_parent(lower_old_dentry);
 621         lower_new_dir_dentry = dget_parent(lower_new_dentry);
 622         lock_rename(lower_old_dir_dentry, lower_new_dir_dentry);
 623         rc = vfs_rename(lower_old_dir_dentry->d_inode, lower_old_dentry,
 624                         lower_new_dir_dentry->d_inode, lower_new_dentry);
 625         if (rc)
 626                 goto out_lock;
 627         fsstack_copy_attr_all(new_dir, lower_new_dir_dentry->d_inode, NULL);
 628         if (new_dir != old_dir)
 629                 fsstack_copy_attr_all(old_dir, lower_old_dir_dentry->d_inode, NULL);
 630 out_lock:
 631         unlock_rename(lower_old_dir_dentry, lower_new_dir_dentry);
 632         dput(lower_new_dentry->d_parent);
 633         dput(lower_old_dentry->d_parent);
 634         dput(lower_new_dentry);
 635         dput(lower_old_dentry);
 636         return rc;
 637 }
 638
 639 static int
 640 ecryptfs_readlink(struct dentry *dentry, char __user *buf, int bufsiz)
 641 {
 642         char *lower_buf;
 643         size_t lower_bufsiz;
 644         struct dentry *lower_dentry;
 645         struct ecryptfs_mount_crypt_stat *mount_crypt_stat;
 646         char *plaintext_name;
 647         size_t plaintext_name_size;
 648         mm_segment_t old_fs;
 649         int rc;
 650
 651         lower_dentry = ecryptfs_dentry_to_lower(dentry);
 652         if (!lower_dentry->d_inode->i_op->readlink) {
 653                 rc = -EINVAL;
 654                 goto out;
 655         }
 656         mount_crypt_stat = &ecryptfs_superblock_to_private(
 657                                                 dentry->d_sb)->mount_crypt_stat;
 658         /*
 659          * If the lower filename is encrypted, it will result in a significantly
 660          * longer name.  If needed, truncate the name after decode and decrypt.
 661          */
 662         if (mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES)
 663                 lower_bufsiz = PATH_MAX;
 664         else
 665                 lower_bufsiz = bufsiz;
 666         /* Released in this function */
 667         lower_buf = kmalloc(lower_bufsiz, GFP_KERNEL);
 668         if (lower_buf == NULL) {
 669                 printk(KERN_ERR "%s: Out of memory whilst attempting to "
 670                        "kmalloc [%zd] bytes\n", __func__, lower_bufsiz);
 671                 rc = -ENOMEM;
 672                 goto out;
 673         }
 674         old_fs = get_fs();
 675         set_fs(get_ds());
 676         rc = lower_dentry->d_inode->i_op->readlink(lower_dentry,
 677                                                    (char __user *)lower_buf,
 678                                                    lower_bufsiz);
 679         set_fs(old_fs);
 680         if (rc >= 0) {
 681                 rc = ecryptfs_decode_and_decrypt_filename(&plaintext_name,
 682                                                           &plaintext_name_size,
 683                                                           dentry, lower_buf,
 684                                                           rc);
 685                 if (rc) {
 686                         printk(KERN_ERR "%s: Error attempting to decode and "
 687                                "decrypt filename; rc = [%d]\n", __func__,
 688                                 rc);
 689                         goto out_free_lower_buf;
 690                 }
 691                 /* Check for bufsiz <= 0 done in sys_readlinkat() */
 692                 rc = copy_to_user(buf, plaintext_name,
 693                                   min((size_t) bufsiz, plaintext_name_size));
 694                 if (rc)
 695                         rc = -EFAULT;
 696                 else
 697                         rc = plaintext_name_size;
 698                 kfree(plaintext_name);
 699                 fsstack_copy_attr_atime(dentry->d_inode, lower_dentry->d_inode);
 700         }
 701 out_free_lower_buf:
 702         kfree(lower_buf);
 703 out:
 704         return rc;
 705 }
 706
 707 static void *ecryptfs_follow_link(struct dentry *dentry, struct nameidata *nd)
 708 {
 709         char *buf;
 710         int len = PAGE_SIZE, rc;
 711         mm_segment_t old_fs;
 712
 713         /* Released in ecryptfs_put_link(); only release here on error */
 714         buf = kmalloc(len, GFP_KERNEL);
 715         if (!buf) {
 716                 rc = -ENOMEM;
 717                 goto out;
 718         }
 719         old_fs = get_fs();
 720         set_fs(get_ds());
 721         rc = dentry->d_inode->i_op->readlink(dentry, (char __user *)buf, len);
 722         set_fs(old_fs);
 723         if (rc < 0)
 724                 goto out_free;
 725         else
 726                 buf[rc] = '\0';
 727         rc = 0;
 728         nd_set_link(nd, buf);
 729         goto out;
 730 out_free:
 731         kfree(buf);
 732 out:
 733         return ERR_PTR(rc);
 734 }
 735
 736 static void
 737 ecryptfs_put_link(struct dentry *dentry, struct nameidata *nd, void *ptr)
 738 {
 739         /* Free the char* */
 740         kfree(nd_get_link(nd));
 741 }
 742
 743 /**
 744  * upper_size_to_lower_size
 745  * @crypt_stat: Crypt_stat associated with file
 746  * @upper_size: Size of the upper file
 747  *
 748  * Calculate the required size of the lower file based on the
 749  * specified size of the upper file. This calculation is based on the
 750  * number of headers in the underlying file and the extent size.
 751  *
 752  * Returns Calculated size of the lower file.
 753  */
 754 static loff_t
 755 upper_size_to_lower_size(struct ecryptfs_crypt_stat *crypt_stat,
 756                          loff_t upper_size)
 757 {
 758         loff_t lower_size;
 759
 760         lower_size = crypt_stat->num_header_bytes_at_front;
 761         if (upper_size != 0) {
 762                 loff_t num_extents;
 763
 764                 num_extents = upper_size >> crypt_stat->extent_shift;
 765                 if (upper_size & ~crypt_stat->extent_mask)
 766                         num_extents++;
 767                 lower_size += (num_extents * crypt_stat->extent_size);
 768         }
 769         return lower_size;
 770 }
 771
 772 /**
 773  * ecryptfs_truncate
 774  * @dentry: The ecryptfs layer dentry
 775  * @new_length: The length to expand the file to
 776  *
 777  * Function to handle truncations modifying the size of the file. Note
 778  * that the file sizes are interpolated. When expanding, we are simply
 779  * writing strings of 0's out. When truncating, we need to modify the
 780  * underlying file size according to the page index interpolations.
 781  *
 782  * Returns zero on success; non-zero otherwise
 783  */
 784 int ecryptfs_truncate(struct dentry *dentry, loff_t new_length)
 785 {
 786         int rc = 0;
 787         struct inode *inode = dentry->d_inode;
 788         struct dentry *lower_dentry;
 789         struct file fake_ecryptfs_file;
 790         struct ecryptfs_crypt_stat *crypt_stat;
 791         loff_t i_size = i_size_read(inode);
 792         loff_t lower_size_before_truncate;
 793         loff_t lower_size_after_truncate;
 794
 795         if (unlikely((new_length == i_size)))
 796                 goto out;
 797         crypt_stat = &ecryptfs_inode_to_private(dentry->d_inode)->crypt_stat;
 798         /* Set up a fake ecryptfs file, this is used to interface with
 799          * the file in the underlying filesystem so that the
 800          * truncation has an effect there as well. */
 801         memset(&fake_ecryptfs_file, 0, sizeof(fake_ecryptfs_file));
 802         fake_ecryptfs_file.f_path.dentry = dentry;
 803         /* Released at out_free: label */
 804         ecryptfs_set_file_private(&fake_ecryptfs_file,
 805                                   kmem_cache_alloc(ecryptfs_file_info_cache,
 806                                                    GFP_KERNEL));
 807         if (unlikely(!ecryptfs_file_to_private(&fake_ecryptfs_file))) {
 808                 rc = -ENOMEM;
 809                 goto out;
 810         }
 811         lower_dentry = ecryptfs_dentry_to_lower(dentry);
 812         ecryptfs_set_file_lower(
 813                 &fake_ecryptfs_file,
 814                 ecryptfs_inode_to_private(dentry->d_inode)->lower_file);
 815         /* Switch on growing or shrinking file */
 816         if (new_length > i_size) {
 817                 char zero[] = { 0x00 };
 818
 819                 /* Write a single 0 at the last position of the file;
 820                  * this triggers code that will fill in 0's throughout
 821                  * the intermediate portion of the previous end of the
 822                  * file and the new and of the file */
 823                 rc = ecryptfs_write(&fake_ecryptfs_file, zero,
 824                                     (new_length - 1), 1);
 825         } else { /* new_length < i_size_read(inode) */
 826                 /* We're chopping off all the pages down do the page
 827                  * in which new_length is located. Fill in the end of
 828                  * that page from (new_length & ~PAGE_CACHE_MASK) to
 829                  * PAGE_CACHE_SIZE with zeros. */
 830                 size_t num_zeros = (PAGE_CACHE_SIZE
 831                                     - (new_length & ~PAGE_CACHE_MASK));
 832
 833                 if (!(crypt_stat->flags & ECRYPTFS_ENCRYPTED)) {
 834                         rc = vmtruncate(inode, new_length);
 835                         if (rc)
 836                                 goto out_free;
 837                         rc = vmtruncate(lower_dentry->d_inode, new_length);
 838                         goto out_free;
 839                 }
 840                 if (num_zeros) {
 841                         char *zeros_virt;
 842
 843                         zeros_virt = kzalloc(num_zeros, GFP_KERNEL);
 844                         if (!zeros_virt) {
 845                                 rc = -ENOMEM;
 846                                 goto out_free;
 847                         }
 848                         rc = ecryptfs_write(&fake_ecryptfs_file, zeros_virt,
 849                                             new_length, num_zeros);
 850                         kfree(zeros_virt);
 851                         if (rc) {
 852                                 printk(KERN_ERR "Error attempting to zero out "
 853                                        "the remainder of the end page on "
 854                                        "reducing truncate; rc = [%d]\n", rc);
 855                                 goto out_free;
 856                         }
 857                 }
 858                 vmtruncate(inode, new_length);
 859                 rc = ecryptfs_write_inode_size_to_metadata(inode);
 860                 if (rc) {
 861                         printk(KERN_ERR "Problem with "
 862                                "ecryptfs_write_inode_size_to_metadata; "
 863                                "rc = [%d]\n", rc);
 864                         goto out_free;
 865                 }
 866                 /* We are reducing the size of the ecryptfs file, and need to
 867                  * know if we need to reduce the size of the lower file. */
 868                 lower_size_before_truncate =
 869                     upper_size_to_lower_size(crypt_stat, i_size);
 870                 lower_size_after_truncate =
 871                     upper_size_to_lower_size(crypt_stat, new_length);
 872                 if (lower_size_after_truncate < lower_size_before_truncate)
 873                         vmtruncate(lower_dentry->d_inode,
 874                                    lower_size_after_truncate);
 875         }
 876 out_free:
 877         if (ecryptfs_file_to_private(&fake_ecryptfs_file))
 878                 kmem_cache_free(ecryptfs_file_info_cache,
 879                                 ecryptfs_file_to_private(&fake_ecryptfs_file));
 880 out:
 881         return rc;
 882 }
 883
 884 static int
 885 ecryptfs_permission(struct inode *inode, int mask)
 886 {
 887         return inode_permission(ecryptfs_inode_to_lower(inode), mask);
 888 }
 889
 890 /**
 891  * ecryptfs_setattr
 892  * @dentry: dentry handle to the inode to modify
 893  * @ia: Structure with flags of what to change and values
 894  *
 895  * Updates the metadata of an inode. If the update is to the size
 896  * i.e. truncation, then ecryptfs_truncate will handle the size modification
 897  * of both the ecryptfs inode and the lower inode.
 898  *
 899  * All other metadata changes will be passed right to the lower filesystem,
 900  * and we will just update our inode to look like the lower.
 901  */
 902 static int ecryptfs_setattr(struct dentry *dentry, struct iattr *ia)
 903 {
 904         int rc = 0;
 905         struct dentry *lower_dentry;
 906         struct inode *inode;
 907         struct inode *lower_inode;
 908         struct ecryptfs_crypt_stat *crypt_stat;
 909
 910         crypt_stat = &ecryptfs_inode_to_private(dentry->d_inode)->crypt_stat;
 911         if (!(crypt_stat->flags & ECRYPTFS_STRUCT_INITIALIZED))
 912                 ecryptfs_init_crypt_stat(crypt_stat);
 913         inode = dentry->d_inode;
 914         lower_inode = ecryptfs_inode_to_lower(inode);
 915         lower_dentry = ecryptfs_dentry_to_lower(dentry);
 916         mutex_lock(&crypt_stat->cs_mutex);
 917         if (S_ISDIR(dentry->d_inode->i_mode))
 918                 crypt_stat->flags &= ~(ECRYPTFS_ENCRYPTED);
 919         else if (S_ISREG(dentry->d_inode->i_mode)
 920                  && (!(crypt_stat->flags & ECRYPTFS_POLICY_APPLIED)
 921                      || !(crypt_stat->flags & ECRYPTFS_KEY_VALID))) {
 922                 struct ecryptfs_mount_crypt_stat *mount_crypt_stat;
 923
 924                 mount_crypt_stat = &ecryptfs_superblock_to_private(
 925                         dentry->d_sb)->mount_crypt_stat;
 926                 rc = ecryptfs_read_metadata(dentry);
 927                 if (rc) {
 928                         if (!(mount_crypt_stat->flags
 929                               & ECRYPTFS_PLAINTEXT_PASSTHROUGH_ENABLED)) {
 930                                 rc = -EIO;
 931                                 printk(KERN_WARNING "Either the lower file "
 932                                        "is not in a valid eCryptfs format, "
 933                                        "or the key could not be retrieved. "
 934                                        "Plaintext passthrough mode is not "
 935                                        "enabled; returning -EIO\n");
 936                                 mutex_unlock(&crypt_stat->cs_mutex);
 937                                 goto out;
 938                         }
 939                         rc = 0;
 940                         crypt_stat->flags &= ~(ECRYPTFS_ENCRYPTED);
 941                 }
 942         }
 943         mutex_unlock(&crypt_stat->cs_mutex);
 944         if (ia->ia_valid & ATTR_SIZE) {
 945                 ecryptfs_printk(KERN_DEBUG,
 946                                 "ia->ia_valid = [0x%x] ATTR_SIZE" " = [0x%x]\n",
 947                                 ia->ia_valid, ATTR_SIZE);
 948                 rc = ecryptfs_truncate(dentry, ia->ia_size);
 949                 /* ecryptfs_truncate handles resizing of the lower file */
 950                 ia->ia_valid &= ~ATTR_SIZE;
 951                 ecryptfs_printk(KERN_DEBUG, "ia->ia_valid = [%x]\n",
 952                                 ia->ia_valid);
 953                 if (rc < 0)
 954                         goto out;
 955         }
 956
 957         /*
 958          * mode change is for clearing setuid/setgid bits. Allow lower fs
 959          * to interpret this in its own way.
 960          */
 961         if (ia->ia_valid & (ATTR_KILL_SUID | ATTR_KILL_SGID))
 962                 ia->ia_valid &= ~ATTR_MODE;
 963
 964         mutex_lock(&lower_dentry->d_inode->i_mutex);
 965         rc = notify_change(lower_dentry, ia);
 966         mutex_unlock(&lower_dentry->d_inode->i_mutex);
 967 out:
 968         fsstack_copy_attr_all(inode, lower_inode, NULL);
 969         return rc;
 970 }
 971
 972 int
 973 ecryptfs_setxattr(struct dentry *dentry, const char *name, const void *value,
 974                   size_t size, int flags)
 975 {
 976         int rc = 0;
 977         struct dentry *lower_dentry;
 978
 979         lower_dentry = ecryptfs_dentry_to_lower(dentry);
 980         if (!lower_dentry->d_inode->i_op->setxattr) {
 981                 rc = -ENOSYS;
 982                 goto out;
 983         }
 984         mutex_lock(&lower_dentry->d_inode->i_mutex);
 985         rc = lower_dentry->d_inode->i_op->setxattr(lower_dentry, name, value,
 986                                                    size, flags);
 987         mutex_unlock(&lower_dentry->d_inode->i_mutex);
 988 out:
 989         return rc;
 990 }
 991
 992 ssize_t
 993 ecryptfs_getxattr_lower(struct dentry *lower_dentry, const char *name,
 994                         void *value, size_t size)
 995 {
 996         int rc = 0;
 997
 998         if (!lower_dentry->d_inode->i_op->getxattr) {
 999                 rc = -ENOSYS;
1000                 goto out;
1001         }
1002         mutex_lock(&lower_dentry->d_inode->i_mutex);
1003         rc = lower_dentry->d_inode->i_op->getxattr(lower_dentry, name, value,
1004                                                    size);
1005         mutex_unlock(&lower_dentry->d_inode->i_mutex);
1006 out:
1007         return rc;
1008 }
1009
1010 static ssize_t
1011 ecryptfs_getxattr(struct dentry *dentry, const char *name, void *value,
1012                   size_t size)
1013 {
1014         return ecryptfs_getxattr_lower(ecryptfs_dentry_to_lower(dentry), name,
1015                                        value, size);
1016 }
1017
1018 static ssize_t
1019 ecryptfs_listxattr(struct dentry *dentry, char *list, size_t size)
1020 {
1021         int rc = 0;
1022         struct dentry *lower_dentry;
1023
1024         lower_dentry = ecryptfs_dentry_to_lower(dentry);
1025         if (!lower_dentry->d_inode->i_op->listxattr) {
1026                 rc = -ENOSYS;
1027                 goto out;
1028         }
1029         mutex_lock(&lower_dentry->d_inode->i_mutex);
1030         rc = lower_dentry->d_inode->i_op->listxattr(lower_dentry, list, size);
1031         mutex_unlock(&lower_dentry->d_inode->i_mutex);
1032 out:
1033         return rc;
1034 }
1035
1036 static int ecryptfs_removexattr(struct dentry *dentry, const char *name)
1037 {
1038         int rc = 0;
1039         struct dentry *lower_dentry;
1040
1041         lower_dentry = ecryptfs_dentry_to_lower(dentry);
1042         if (!lower_dentry->d_inode->i_op->removexattr) {
1043                 rc = -ENOSYS;
1044                 goto out;
1045         }
1046         mutex_lock(&lower_dentry->d_inode->i_mutex);
1047         rc = lower_dentry->d_inode->i_op->removexattr(lower_dentry, name);
1048         mutex_unlock(&lower_dentry->d_inode->i_mutex);
1049 out:
1050         return rc;
1051 }
1052
1053 int ecryptfs_inode_test(struct inode *inode, void *candidate_lower_inode)
1054 {
1055         if ((ecryptfs_inode_to_lower(inode)
1056              == (struct inode *)candidate_lower_inode))
1057                 return 1;
1058         else
1059                 return 0;
1060 }
1061
1062 int ecryptfs_inode_set(struct inode *inode, void *lower_inode)
1063 {
1064         ecryptfs_init_inode(inode, (struct inode *)lower_inode);
1065         return 0;
1066 }
1067
1068 const struct inode_operations ecryptfs_symlink_iops = {
1069         .readlink = ecryptfs_readlink,
1070         .follow_link = ecryptfs_follow_link,
1071         .put_link = ecryptfs_put_link,
1072         .permission = ecryptfs_permission,
1073         .setattr = ecryptfs_setattr,
1074         .setxattr = ecryptfs_setxattr,
1075         .getxattr = ecryptfs_getxattr,
1076         .listxattr = ecryptfs_listxattr,
1077         .removexattr = ecryptfs_removexattr
1078 };
1079
1080 const struct inode_operations ecryptfs_dir_iops = {
1081         .create = ecryptfs_create,
1082         .lookup = ecryptfs_lookup,
1083         .link = ecryptfs_link,
1084         .unlink = ecryptfs_unlink,
1085         .symlink = ecryptfs_symlink,
1086         .mkdir = ecryptfs_mkdir,
1087         .rmdir = ecryptfs_rmdir,
1088         .mknod = ecryptfs_mknod,
1089         .rename = ecryptfs_rename,
1090         .permission = ecryptfs_permission,
1091         .setattr = ecryptfs_setattr,
1092         .setxattr = ecryptfs_setxattr,
1093         .getxattr = ecryptfs_getxattr,
1094         .listxattr = ecryptfs_listxattr,
1095         .removexattr = ecryptfs_removexattr
1096 };
1097
1098 const struct inode_operations ecryptfs_main_iops = {
1099         .permission = ecryptfs_permission,
1100         .setattr = ecryptfs_setattr,
1101         .setxattr = ecryptfs_setxattr,
1102         .getxattr = ecryptfs_getxattr,
1103         .listxattr = ecryptfs_listxattr,
1104         .removexattr = ecryptfs_removexattr
1105 };