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 ecryptfs_crypt_stat *crypt_stat,
 250                                         struct inode *ecryptfs_dir_inode,
 251                                         struct nameidata *ecryptfs_nd)
 252 {
 253         struct dentry *lower_dir_dentry;
 254         struct vfsmount *lower_mnt;
 255         struct inode *lower_inode;
 256         struct ecryptfs_mount_crypt_stat *mount_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         rc = ecryptfs_read_and_validate_header_region(page_virt,
 318                                                       ecryptfs_dentry->d_inode);
 319         if (rc) {
 320                 rc = ecryptfs_read_and_validate_xattr_region(page_virt,
 321                                                              ecryptfs_dentry);
 322                 if (rc) {
 323                         rc = 0;
 324                         goto out_free_kmem;
 325                 }
 326                 crypt_stat->flags |= ECRYPTFS_METADATA_IN_XATTR;
 327         }
 328         mount_crypt_stat = &ecryptfs_superblock_to_private(
 329                 ecryptfs_dentry->d_sb)->mount_crypt_stat;
 330         if (mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED) {
 331                 if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR)
 332                         file_size = (crypt_stat->num_header_bytes_at_front
 333                                      + i_size_read(lower_dentry->d_inode));
 334                 else
 335                         file_size = i_size_read(lower_dentry->d_inode);
 336         } else {
 337                 file_size = get_unaligned_be64(page_virt);
 338         }
 339         i_size_write(ecryptfs_dentry->d_inode, (loff_t)file_size);
 340 out_free_kmem:
 341         kmem_cache_free(ecryptfs_header_cache_2, page_virt);
 342         goto out;
 343 out_dput:
 344         dput(lower_dentry);
 345         d_drop(ecryptfs_dentry);
 346 out:
 347         return rc;
 348 }
 349
 350 /**
 351  * ecryptfs_lookup
 352  * @ecryptfs_dir_inode: The eCryptfs directory inode
 353  * @ecryptfs_dentry: The eCryptfs dentry that we are looking up
 354  * @ecryptfs_nd: nameidata; may be NULL
 355  *
 356  * Find a file on disk. If the file does not exist, then we'll add it to the
 357  * dentry cache and continue on to read it from the disk.
 358  */
 359 static struct dentry *ecryptfs_lookup(struct inode *ecryptfs_dir_inode,
 360                                       struct dentry *ecryptfs_dentry,
 361                                       struct nameidata *ecryptfs_nd)
 362 {
 363         char *encrypted_and_encoded_name = NULL;
 364         size_t encrypted_and_encoded_name_size;
 365         struct ecryptfs_crypt_stat *crypt_stat = NULL;
 366         struct ecryptfs_mount_crypt_stat *mount_crypt_stat = NULL;
 367         struct ecryptfs_inode_info *inode_info;
 368         struct dentry *lower_dir_dentry, *lower_dentry;
 369         int rc = 0;
 370
 371         ecryptfs_dentry->d_op = &ecryptfs_dops;
 372         if ((ecryptfs_dentry->d_name.len == 1
 373              && !strcmp(ecryptfs_dentry->d_name.name, "."))
 374             || (ecryptfs_dentry->d_name.len == 2
 375                 && !strcmp(ecryptfs_dentry->d_name.name, ".."))) {
 376                 goto out_d_drop;
 377         }
 378         lower_dir_dentry = ecryptfs_dentry_to_lower(ecryptfs_dentry->d_parent);
 379         lower_dentry = lookup_one_len(ecryptfs_dentry->d_name.name,
 380                                       lower_dir_dentry,
 381                                       ecryptfs_dentry->d_name.len);
 382         if (IS_ERR(lower_dentry)) {
 383                 rc = PTR_ERR(lower_dentry);
 384                 printk(KERN_ERR "%s: lookup_one_len() returned [%d] on "
 385                        "lower_dentry = [%s]\n", __func__, rc,
 386                        ecryptfs_dentry->d_name.name);
 387                 goto out_d_drop;
 388         }
 389         if (lower_dentry->d_inode)
 390                 goto lookup_and_interpose;
 391         inode_info =  ecryptfs_inode_to_private(ecryptfs_dentry->d_inode);
 392         if (inode_info) {
 393                 crypt_stat = &inode_info->crypt_stat;
 394                 /* TODO: lock for crypt_stat comparison */
 395                 if (!(crypt_stat->flags & ECRYPTFS_POLICY_APPLIED))
 396                         ecryptfs_set_default_sizes(crypt_stat);
 397         }
 398         if (crypt_stat)
 399                 mount_crypt_stat = crypt_stat->mount_crypt_stat;
 400         else
 401                 mount_crypt_stat = &ecryptfs_superblock_to_private(
 402                         ecryptfs_dentry->d_sb)->mount_crypt_stat;
 403         if (!(crypt_stat && (crypt_stat->flags & ECRYPTFS_ENCRYPT_FILENAMES))
 404             && !(mount_crypt_stat && (mount_crypt_stat->flags
 405                                      & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES)))
 406                 goto lookup_and_interpose;
 407         dput(lower_dentry);
 408         rc = ecryptfs_encrypt_and_encode_filename(
 409                 &encrypted_and_encoded_name, &encrypted_and_encoded_name_size,
 410                 crypt_stat, mount_crypt_stat, ecryptfs_dentry->d_name.name,
 411                 ecryptfs_dentry->d_name.len);
 412         if (rc) {
 413                 printk(KERN_ERR "%s: Error attempting to encrypt and encode "
 414                        "filename; rc = [%d]\n", __func__, rc);
 415                 goto out_d_drop;
 416         }
 417         lower_dentry = lookup_one_len(encrypted_and_encoded_name,
 418                                       lower_dir_dentry,
 419                                       encrypted_and_encoded_name_size - 1);
 420         if (IS_ERR(lower_dentry)) {
 421                 rc = PTR_ERR(lower_dentry);
 422                 printk(KERN_ERR "%s: lookup_one_len() returned [%d] on "
 423                        "lower_dentry = [%s]\n", __func__, rc,
 424                        encrypted_and_encoded_name);
 425                 goto out_d_drop;
 426         }
 427 lookup_and_interpose:
 428         rc = ecryptfs_lookup_and_interpose_lower(ecryptfs_dentry, lower_dentry,
 429                                                  crypt_stat, ecryptfs_dir_inode,
 430                                                  ecryptfs_nd);
 431         goto out;
 432 out_d_drop:
 433         d_drop(ecryptfs_dentry);
 434 out:
 435         kfree(encrypted_and_encoded_name);
 436         return ERR_PTR(rc);
 437 }
 438
 439 static int ecryptfs_link(struct dentry *old_dentry, struct inode *dir,
 440                          struct dentry *new_dentry)
 441 {
 442         struct dentry *lower_old_dentry;
 443         struct dentry *lower_new_dentry;
 444         struct dentry *lower_dir_dentry;
 445         u64 file_size_save;
 446         int rc;
 447
 448         file_size_save = i_size_read(old_dentry->d_inode);
 449         lower_old_dentry = ecryptfs_dentry_to_lower(old_dentry);
 450         lower_new_dentry = ecryptfs_dentry_to_lower(new_dentry);
 451         dget(lower_old_dentry);
 452         dget(lower_new_dentry);
 453         lower_dir_dentry = lock_parent(lower_new_dentry);
 454         rc = vfs_link(lower_old_dentry, lower_dir_dentry->d_inode,
 455                       lower_new_dentry);
 456         if (rc || !lower_new_dentry->d_inode)
 457                 goto out_lock;
 458         rc = ecryptfs_interpose(lower_new_dentry, new_dentry, dir->i_sb, 0);
 459         if (rc)
 460                 goto out_lock;
 461         fsstack_copy_attr_times(dir, lower_new_dentry->d_inode);
 462         fsstack_copy_inode_size(dir, lower_new_dentry->d_inode);
 463         old_dentry->d_inode->i_nlink =
 464                 ecryptfs_inode_to_lower(old_dentry->d_inode)->i_nlink;
 465         i_size_write(new_dentry->d_inode, file_size_save);
 466 out_lock:
 467         unlock_dir(lower_dir_dentry);
 468         dput(lower_new_dentry);
 469         dput(lower_old_dentry);
 470         d_drop(lower_old_dentry);
 471         d_drop(new_dentry);
 472         d_drop(old_dentry);
 473         return rc;
 474 }
 475
 476 static int ecryptfs_unlink(struct inode *dir, struct dentry *dentry)
 477 {
 478         int rc = 0;
 479         struct dentry *lower_dentry = ecryptfs_dentry_to_lower(dentry);
 480         struct inode *lower_dir_inode = ecryptfs_inode_to_lower(dir);
 481         struct dentry *lower_dir_dentry;
 482
 483         lower_dir_dentry = lock_parent(lower_dentry);
 484         rc = vfs_unlink(lower_dir_inode, lower_dentry);
 485         if (rc) {
 486                 printk(KERN_ERR "Error in vfs_unlink; rc = [%d]\n", rc);
 487                 goto out_unlock;
 488         }
 489         fsstack_copy_attr_times(dir, lower_dir_inode);
 490         dentry->d_inode->i_nlink =
 491                 ecryptfs_inode_to_lower(dentry->d_inode)->i_nlink;
 492         dentry->d_inode->i_ctime = dir->i_ctime;
 493         d_drop(dentry);
 494 out_unlock:
 495         unlock_dir(lower_dir_dentry);
 496         return rc;
 497 }
 498
 499 static int ecryptfs_symlink(struct inode *dir, struct dentry *dentry,
 500                             const char *symname)
 501 {
 502         int rc;
 503         struct dentry *lower_dentry;
 504         struct dentry *lower_dir_dentry;
 505         char *encoded_symname;
 506         size_t encoded_symlen;
 507         struct ecryptfs_mount_crypt_stat *mount_crypt_stat = NULL;
 508
 509         lower_dentry = ecryptfs_dentry_to_lower(dentry);
 510         dget(lower_dentry);
 511         lower_dir_dentry = lock_parent(lower_dentry);
 512         mount_crypt_stat = &ecryptfs_superblock_to_private(
 513                 dir->i_sb)->mount_crypt_stat;
 514         rc = ecryptfs_encrypt_and_encode_filename(&encoded_symname,
 515                                                   &encoded_symlen,
 516                                                   NULL,
 517                                                   mount_crypt_stat, symname,
 518                                                   strlen(symname));
 519         if (rc)
 520                 goto out_lock;
 521         rc = vfs_symlink(lower_dir_dentry->d_inode, lower_dentry,
 522                          encoded_symname);
 523         kfree(encoded_symname);
 524         if (rc || !lower_dentry->d_inode)
 525                 goto out_lock;
 526         rc = ecryptfs_interpose(lower_dentry, dentry, dir->i_sb, 0);
 527         if (rc)
 528                 goto out_lock;
 529         fsstack_copy_attr_times(dir, lower_dir_dentry->d_inode);
 530         fsstack_copy_inode_size(dir, lower_dir_dentry->d_inode);
 531 out_lock:
 532         unlock_dir(lower_dir_dentry);
 533         dput(lower_dentry);
 534         if (!dentry->d_inode)
 535                 d_drop(dentry);
 536         return rc;
 537 }
 538
 539 static int ecryptfs_mkdir(struct inode *dir, struct dentry *dentry, int mode)
 540 {
 541         int rc;
 542         struct dentry *lower_dentry;
 543         struct dentry *lower_dir_dentry;
 544
 545         lower_dentry = ecryptfs_dentry_to_lower(dentry);
 546         lower_dir_dentry = lock_parent(lower_dentry);
 547         rc = vfs_mkdir(lower_dir_dentry->d_inode, lower_dentry, mode);
 548         if (rc || !lower_dentry->d_inode)
 549                 goto out;
 550         rc = ecryptfs_interpose(lower_dentry, dentry, dir->i_sb, 0);
 551         if (rc)
 552                 goto out;
 553         fsstack_copy_attr_times(dir, lower_dir_dentry->d_inode);
 554         fsstack_copy_inode_size(dir, lower_dir_dentry->d_inode);
 555         dir->i_nlink = lower_dir_dentry->d_inode->i_nlink;
 556 out:
 557         unlock_dir(lower_dir_dentry);
 558         if (!dentry->d_inode)
 559                 d_drop(dentry);
 560         return rc;
 561 }
 562
 563 static int ecryptfs_rmdir(struct inode *dir, struct dentry *dentry)
 564 {
 565         struct dentry *lower_dentry;
 566         struct dentry *lower_dir_dentry;
 567         int rc;
 568
 569         lower_dentry = ecryptfs_dentry_to_lower(dentry);
 570         dget(dentry);
 571         lower_dir_dentry = lock_parent(lower_dentry);
 572         dget(lower_dentry);
 573         rc = vfs_rmdir(lower_dir_dentry->d_inode, lower_dentry);
 574         dput(lower_dentry);
 575         if (!rc)
 576                 d_delete(lower_dentry);
 577         fsstack_copy_attr_times(dir, lower_dir_dentry->d_inode);
 578         dir->i_nlink = lower_dir_dentry->d_inode->i_nlink;
 579         unlock_dir(lower_dir_dentry);
 580         if (!rc)
 581                 d_drop(dentry);
 582         dput(dentry);
 583         return rc;
 584 }
 585
 586 static int
 587 ecryptfs_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev)
 588 {
 589         int rc;
 590         struct dentry *lower_dentry;
 591         struct dentry *lower_dir_dentry;
 592
 593         lower_dentry = ecryptfs_dentry_to_lower(dentry);
 594         lower_dir_dentry = lock_parent(lower_dentry);
 595         rc = vfs_mknod(lower_dir_dentry->d_inode, lower_dentry, mode, dev);
 596         if (rc || !lower_dentry->d_inode)
 597                 goto out;
 598         rc = ecryptfs_interpose(lower_dentry, dentry, dir->i_sb, 0);
 599         if (rc)
 600                 goto out;
 601         fsstack_copy_attr_times(dir, lower_dir_dentry->d_inode);
 602         fsstack_copy_inode_size(dir, lower_dir_dentry->d_inode);
 603 out:
 604         unlock_dir(lower_dir_dentry);
 605         if (!dentry->d_inode)
 606                 d_drop(dentry);
 607         return rc;
 608 }
 609
 610 static int
 611 ecryptfs_rename(struct inode *old_dir, struct dentry *old_dentry,
 612                 struct inode *new_dir, struct dentry *new_dentry)
 613 {
 614         int rc;
 615         struct dentry *lower_old_dentry;
 616         struct dentry *lower_new_dentry;
 617         struct dentry *lower_old_dir_dentry;
 618         struct dentry *lower_new_dir_dentry;
 619
 620         lower_old_dentry = ecryptfs_dentry_to_lower(old_dentry);
 621         lower_new_dentry = ecryptfs_dentry_to_lower(new_dentry);
 622         dget(lower_old_dentry);
 623         dget(lower_new_dentry);
 624         lower_old_dir_dentry = dget_parent(lower_old_dentry);
 625         lower_new_dir_dentry = dget_parent(lower_new_dentry);
 626         lock_rename(lower_old_dir_dentry, lower_new_dir_dentry);
 627         rc = vfs_rename(lower_old_dir_dentry->d_inode, lower_old_dentry,
 628                         lower_new_dir_dentry->d_inode, lower_new_dentry);
 629         if (rc)
 630                 goto out_lock;
 631         fsstack_copy_attr_all(new_dir, lower_new_dir_dentry->d_inode, NULL);
 632         if (new_dir != old_dir)
 633                 fsstack_copy_attr_all(old_dir, lower_old_dir_dentry->d_inode, NULL);
 634 out_lock:
 635         unlock_rename(lower_old_dir_dentry, lower_new_dir_dentry);
 636         dput(lower_new_dentry->d_parent);
 637         dput(lower_old_dentry->d_parent);
 638         dput(lower_new_dentry);
 639         dput(lower_old_dentry);
 640         return rc;
 641 }
 642
 643 static int
 644 ecryptfs_readlink(struct dentry *dentry, char __user *buf, int bufsiz)
 645 {
 646         char *lower_buf;
 647         struct dentry *lower_dentry;
 648         struct ecryptfs_crypt_stat *crypt_stat;
 649         char *plaintext_name;
 650         size_t plaintext_name_size;
 651         mm_segment_t old_fs;
 652         int rc;
 653
 654         lower_dentry = ecryptfs_dentry_to_lower(dentry);
 655         if (!lower_dentry->d_inode->i_op->readlink) {
 656                 rc = -EINVAL;
 657                 goto out;
 658         }
 659         crypt_stat = &ecryptfs_inode_to_private(dentry->d_inode)->crypt_stat;
 660         /* Released in this function */
 661         lower_buf = kmalloc(bufsiz, GFP_KERNEL);
 662         if (lower_buf == NULL) {
 663                 printk(KERN_ERR "%s: Out of memory whilst attempting to "
 664                        "kmalloc [%d] bytes\n", __func__, bufsiz);
 665                 rc = -ENOMEM;
 666                 goto out;
 667         }
 668         old_fs = get_fs();
 669         set_fs(get_ds());
 670         rc = lower_dentry->d_inode->i_op->readlink(lower_dentry,
 671                                                    (char __user *)lower_buf,
 672                                                    bufsiz);
 673         set_fs(old_fs);
 674         if (rc >= 0) {
 675                 rc = ecryptfs_decode_and_decrypt_filename(&plaintext_name,
 676                                                           &plaintext_name_size,
 677                                                           dentry, lower_buf,
 678                                                           rc);
 679                 if (rc) {
 680                         printk(KERN_ERR "%s: Error attempting to decode and "
 681                                "decrypt filename; rc = [%d]\n", __func__,
 682                                 rc);
 683                         goto out_free_lower_buf;
 684                 }
 685                 rc = copy_to_user(buf, plaintext_name, plaintext_name_size);
 686                 if (rc)
 687                         rc = -EFAULT;
 688                 else
 689                         rc = plaintext_name_size;
 690                 kfree(plaintext_name);
 691                 fsstack_copy_attr_atime(dentry->d_inode, lower_dentry->d_inode);
 692         }
 693 out_free_lower_buf:
 694         kfree(lower_buf);
 695 out:
 696         return rc;
 697 }
 698
 699 static void *ecryptfs_follow_link(struct dentry *dentry, struct nameidata *nd)
 700 {
 701         char *buf;
 702         int len = PAGE_SIZE, rc;
 703         mm_segment_t old_fs;
 704
 705         /* Released in ecryptfs_put_link(); only release here on error */
 706         buf = kmalloc(len, GFP_KERNEL);
 707         if (!buf) {
 708                 rc = -ENOMEM;
 709                 goto out;
 710         }
 711         old_fs = get_fs();
 712         set_fs(get_ds());
 713         rc = dentry->d_inode->i_op->readlink(dentry, (char __user *)buf, len);
 714         set_fs(old_fs);
 715         if (rc < 0)
 716                 goto out_free;
 717         else
 718                 buf[rc] = '\0';
 719         rc = 0;
 720         nd_set_link(nd, buf);
 721         goto out;
 722 out_free:
 723         kfree(buf);
 724 out:
 725         return ERR_PTR(rc);
 726 }
 727
 728 static void
 729 ecryptfs_put_link(struct dentry *dentry, struct nameidata *nd, void *ptr)
 730 {
 731         /* Free the char* */
 732         kfree(nd_get_link(nd));
 733 }
 734
 735 /**
 736  * upper_size_to_lower_size
 737  * @crypt_stat: Crypt_stat associated with file
 738  * @upper_size: Size of the upper file
 739  *
 740  * Calculate the required size of the lower file based on the
 741  * specified size of the upper file. This calculation is based on the
 742  * number of headers in the underlying file and the extent size.
 743  *
 744  * Returns Calculated size of the lower file.
 745  */
 746 static loff_t
 747 upper_size_to_lower_size(struct ecryptfs_crypt_stat *crypt_stat,
 748                          loff_t upper_size)
 749 {
 750         loff_t lower_size;
 751
 752         lower_size = crypt_stat->num_header_bytes_at_front;
 753         if (upper_size != 0) {
 754                 loff_t num_extents;
 755
 756                 num_extents = upper_size >> crypt_stat->extent_shift;
 757                 if (upper_size & ~crypt_stat->extent_mask)
 758                         num_extents++;
 759                 lower_size += (num_extents * crypt_stat->extent_size);
 760         }
 761         return lower_size;
 762 }
 763
 764 /**
 765  * ecryptfs_truncate
 766  * @dentry: The ecryptfs layer dentry
 767  * @new_length: The length to expand the file to
 768  *
 769  * Function to handle truncations modifying the size of the file. Note
 770  * that the file sizes are interpolated. When expanding, we are simply
 771  * writing strings of 0's out. When truncating, we need to modify the
 772  * underlying file size according to the page index interpolations.
 773  *
 774  * Returns zero on success; non-zero otherwise
 775  */
 776 int ecryptfs_truncate(struct dentry *dentry, loff_t new_length)
 777 {
 778         int rc = 0;
 779         struct inode *inode = dentry->d_inode;
 780         struct dentry *lower_dentry;
 781         struct file fake_ecryptfs_file;
 782         struct ecryptfs_crypt_stat *crypt_stat;
 783         loff_t i_size = i_size_read(inode);
 784         loff_t lower_size_before_truncate;
 785         loff_t lower_size_after_truncate;
 786
 787         if (unlikely((new_length == i_size)))
 788                 goto out;
 789         crypt_stat = &ecryptfs_inode_to_private(dentry->d_inode)->crypt_stat;
 790         /* Set up a fake ecryptfs file, this is used to interface with
 791          * the file in the underlying filesystem so that the
 792          * truncation has an effect there as well. */
 793         memset(&fake_ecryptfs_file, 0, sizeof(fake_ecryptfs_file));
 794         fake_ecryptfs_file.f_path.dentry = dentry;
 795         /* Released at out_free: label */
 796         ecryptfs_set_file_private(&fake_ecryptfs_file,
 797                                   kmem_cache_alloc(ecryptfs_file_info_cache,
 798                                                    GFP_KERNEL));
 799         if (unlikely(!ecryptfs_file_to_private(&fake_ecryptfs_file))) {
 800                 rc = -ENOMEM;
 801                 goto out;
 802         }
 803         lower_dentry = ecryptfs_dentry_to_lower(dentry);
 804         ecryptfs_set_file_lower(
 805                 &fake_ecryptfs_file,
 806                 ecryptfs_inode_to_private(dentry->d_inode)->lower_file);
 807         /* Switch on growing or shrinking file */
 808         if (new_length > i_size) {
 809                 char zero[] = { 0x00 };
 810
 811                 /* Write a single 0 at the last position of the file;
 812                  * this triggers code that will fill in 0's throughout
 813                  * the intermediate portion of the previous end of the
 814                  * file and the new and of the file */
 815                 rc = ecryptfs_write(&fake_ecryptfs_file, zero,
 816                                     (new_length - 1), 1);
 817         } else { /* new_length < i_size_read(inode) */
 818                 /* We're chopping off all the pages down do the page
 819                  * in which new_length is located. Fill in the end of
 820                  * that page from (new_length & ~PAGE_CACHE_MASK) to
 821                  * PAGE_CACHE_SIZE with zeros. */
 822                 size_t num_zeros = (PAGE_CACHE_SIZE
 823                                     - (new_length & ~PAGE_CACHE_MASK));
 824
 825                 if (num_zeros) {
 826                         char *zeros_virt;
 827
 828                         zeros_virt = kzalloc(num_zeros, GFP_KERNEL);
 829                         if (!zeros_virt) {
 830                                 rc = -ENOMEM;
 831                                 goto out_free;
 832                         }
 833                         rc = ecryptfs_write(&fake_ecryptfs_file, zeros_virt,
 834                                             new_length, num_zeros);
 835                         kfree(zeros_virt);
 836                         if (rc) {
 837                                 printk(KERN_ERR "Error attempting to zero out "
 838                                        "the remainder of the end page on "
 839                                        "reducing truncate; rc = [%d]\n", rc);
 840                                 goto out_free;
 841                         }
 842                 }
 843                 vmtruncate(inode, new_length);
 844                 rc = ecryptfs_write_inode_size_to_metadata(inode);
 845                 if (rc) {
 846                         printk(KERN_ERR "Problem with "
 847                                "ecryptfs_write_inode_size_to_metadata; "
 848                                "rc = [%d]\n", rc);
 849                         goto out_free;
 850                 }
 851                 /* We are reducing the size of the ecryptfs file, and need to
 852                  * know if we need to reduce the size of the lower file. */
 853                 lower_size_before_truncate =
 854                     upper_size_to_lower_size(crypt_stat, i_size);
 855                 lower_size_after_truncate =
 856                     upper_size_to_lower_size(crypt_stat, new_length);
 857                 if (lower_size_after_truncate < lower_size_before_truncate)
 858                         vmtruncate(lower_dentry->d_inode,
 859                                    lower_size_after_truncate);
 860         }
 861 out_free:
 862         if (ecryptfs_file_to_private(&fake_ecryptfs_file))
 863                 kmem_cache_free(ecryptfs_file_info_cache,
 864                                 ecryptfs_file_to_private(&fake_ecryptfs_file));
 865 out:
 866         return rc;
 867 }
 868
 869 static int
 870 ecryptfs_permission(struct inode *inode, int mask)
 871 {
 872         return inode_permission(ecryptfs_inode_to_lower(inode), mask);
 873 }
 874
 875 /**
 876  * ecryptfs_setattr
 877  * @dentry: dentry handle to the inode to modify
 878  * @ia: Structure with flags of what to change and values
 879  *
 880  * Updates the metadata of an inode. If the update is to the size
 881  * i.e. truncation, then ecryptfs_truncate will handle the size modification
 882  * of both the ecryptfs inode and the lower inode.
 883  *
 884  * All other metadata changes will be passed right to the lower filesystem,
 885  * and we will just update our inode to look like the lower.
 886  */
 887 static int ecryptfs_setattr(struct dentry *dentry, struct iattr *ia)
 888 {
 889         int rc = 0;
 890         struct dentry *lower_dentry;
 891         struct inode *inode;
 892         struct inode *lower_inode;
 893         struct ecryptfs_crypt_stat *crypt_stat;
 894
 895         crypt_stat = &ecryptfs_inode_to_private(dentry->d_inode)->crypt_stat;
 896         if (!(crypt_stat->flags & ECRYPTFS_STRUCT_INITIALIZED))
 897                 ecryptfs_init_crypt_stat(crypt_stat);
 898         inode = dentry->d_inode;
 899         lower_inode = ecryptfs_inode_to_lower(inode);
 900         lower_dentry = ecryptfs_dentry_to_lower(dentry);
 901         mutex_lock(&crypt_stat->cs_mutex);
 902         if (S_ISDIR(dentry->d_inode->i_mode))
 903                 crypt_stat->flags &= ~(ECRYPTFS_ENCRYPTED);
 904         else if (S_ISREG(dentry->d_inode->i_mode)
 905                  && (!(crypt_stat->flags & ECRYPTFS_POLICY_APPLIED)
 906                      || !(crypt_stat->flags & ECRYPTFS_KEY_VALID))) {
 907                 struct ecryptfs_mount_crypt_stat *mount_crypt_stat;
 908
 909                 mount_crypt_stat = &ecryptfs_superblock_to_private(
 910                         dentry->d_sb)->mount_crypt_stat;
 911                 rc = ecryptfs_read_metadata(dentry);
 912                 if (rc) {
 913                         if (!(mount_crypt_stat->flags
 914                               & ECRYPTFS_PLAINTEXT_PASSTHROUGH_ENABLED)) {
 915                                 rc = -EIO;
 916                                 printk(KERN_WARNING "Either the lower file "
 917                                        "is not in a valid eCryptfs format, "
 918                                        "or the key could not be retrieved. "
 919                                        "Plaintext passthrough mode is not "
 920                                        "enabled; returning -EIO\n");
 921                                 mutex_unlock(&crypt_stat->cs_mutex);
 922                                 goto out;
 923                         }
 924                         rc = 0;
 925                         crypt_stat->flags &= ~(ECRYPTFS_ENCRYPTED);
 926                         mutex_unlock(&crypt_stat->cs_mutex);
 927                         goto out;
 928                 }
 929         }
 930         mutex_unlock(&crypt_stat->cs_mutex);
 931         if (ia->ia_valid & ATTR_SIZE) {
 932                 ecryptfs_printk(KERN_DEBUG,
 933                                 "ia->ia_valid = [0x%x] ATTR_SIZE" " = [0x%x]\n",
 934                                 ia->ia_valid, ATTR_SIZE);
 935                 rc = ecryptfs_truncate(dentry, ia->ia_size);
 936                 /* ecryptfs_truncate handles resizing of the lower file */
 937                 ia->ia_valid &= ~ATTR_SIZE;
 938                 ecryptfs_printk(KERN_DEBUG, "ia->ia_valid = [%x]\n",
 939                                 ia->ia_valid);
 940                 if (rc < 0)
 941                         goto out;
 942         }
 943
 944         /*
 945          * mode change is for clearing setuid/setgid bits. Allow lower fs
 946          * to interpret this in its own way.
 947          */
 948         if (ia->ia_valid & (ATTR_KILL_SUID | ATTR_KILL_SGID))
 949                 ia->ia_valid &= ~ATTR_MODE;
 950
 951         mutex_lock(&lower_dentry->d_inode->i_mutex);
 952         rc = notify_change(lower_dentry, ia);
 953         mutex_unlock(&lower_dentry->d_inode->i_mutex);
 954 out:
 955         fsstack_copy_attr_all(inode, lower_inode, NULL);
 956         return rc;
 957 }
 958
 959 int
 960 ecryptfs_setxattr(struct dentry *dentry, const char *name, const void *value,
 961                   size_t size, int flags)
 962 {
 963         int rc = 0;
 964         struct dentry *lower_dentry;
 965
 966         lower_dentry = ecryptfs_dentry_to_lower(dentry);
 967         if (!lower_dentry->d_inode->i_op->setxattr) {
 968                 rc = -ENOSYS;
 969                 goto out;
 970         }
 971         mutex_lock(&lower_dentry->d_inode->i_mutex);
 972         rc = lower_dentry->d_inode->i_op->setxattr(lower_dentry, name, value,
 973                                                    size, flags);
 974         mutex_unlock(&lower_dentry->d_inode->i_mutex);
 975 out:
 976         return rc;
 977 }
 978
 979 ssize_t
 980 ecryptfs_getxattr_lower(struct dentry *lower_dentry, const char *name,
 981                         void *value, size_t size)
 982 {
 983         int rc = 0;
 984
 985         if (!lower_dentry->d_inode->i_op->getxattr) {
 986                 rc = -ENOSYS;
 987                 goto out;
 988         }
 989         mutex_lock(&lower_dentry->d_inode->i_mutex);
 990         rc = lower_dentry->d_inode->i_op->getxattr(lower_dentry, name, value,
 991                                                    size);
 992         mutex_unlock(&lower_dentry->d_inode->i_mutex);
 993 out:
 994         return rc;
 995 }
 996
 997 static ssize_t
 998 ecryptfs_getxattr(struct dentry *dentry, const char *name, void *value,
 999                   size_t size)
1000 {
1001         return ecryptfs_getxattr_lower(ecryptfs_dentry_to_lower(dentry), name,
1002                                        value, size);
1003 }
1004
1005 static ssize_t
1006 ecryptfs_listxattr(struct dentry *dentry, char *list, size_t size)
1007 {
1008         int rc = 0;
1009         struct dentry *lower_dentry;
1010
1011         lower_dentry = ecryptfs_dentry_to_lower(dentry);
1012         if (!lower_dentry->d_inode->i_op->listxattr) {
1013                 rc = -ENOSYS;
1014                 goto out;
1015         }
1016         mutex_lock(&lower_dentry->d_inode->i_mutex);
1017         rc = lower_dentry->d_inode->i_op->listxattr(lower_dentry, list, size);
1018         mutex_unlock(&lower_dentry->d_inode->i_mutex);
1019 out:
1020         return rc;
1021 }
1022
1023 static int ecryptfs_removexattr(struct dentry *dentry, const char *name)
1024 {
1025         int rc = 0;
1026         struct dentry *lower_dentry;
1027
1028         lower_dentry = ecryptfs_dentry_to_lower(dentry);
1029         if (!lower_dentry->d_inode->i_op->removexattr) {
1030                 rc = -ENOSYS;
1031                 goto out;
1032         }
1033         mutex_lock(&lower_dentry->d_inode->i_mutex);
1034         rc = lower_dentry->d_inode->i_op->removexattr(lower_dentry, name);
1035         mutex_unlock(&lower_dentry->d_inode->i_mutex);
1036 out:
1037         return rc;
1038 }
1039
1040 int ecryptfs_inode_test(struct inode *inode, void *candidate_lower_inode)
1041 {
1042         if ((ecryptfs_inode_to_lower(inode)
1043              == (struct inode *)candidate_lower_inode))
1044                 return 1;
1045         else
1046                 return 0;
1047 }
1048
1049 int ecryptfs_inode_set(struct inode *inode, void *lower_inode)
1050 {
1051         ecryptfs_init_inode(inode, (struct inode *)lower_inode);
1052         return 0;
1053 }
1054
1055 const struct inode_operations ecryptfs_symlink_iops = {
1056         .readlink = ecryptfs_readlink,
1057         .follow_link = ecryptfs_follow_link,
1058         .put_link = ecryptfs_put_link,
1059         .permission = ecryptfs_permission,
1060         .setattr = ecryptfs_setattr,
1061         .setxattr = ecryptfs_setxattr,
1062         .getxattr = ecryptfs_getxattr,
1063         .listxattr = ecryptfs_listxattr,
1064         .removexattr = ecryptfs_removexattr
1065 };
1066
1067 const struct inode_operations ecryptfs_dir_iops = {
1068         .create = ecryptfs_create,
1069         .lookup = ecryptfs_lookup,
1070         .link = ecryptfs_link,
1071         .unlink = ecryptfs_unlink,
1072         .symlink = ecryptfs_symlink,
1073         .mkdir = ecryptfs_mkdir,
1074         .rmdir = ecryptfs_rmdir,
1075         .mknod = ecryptfs_mknod,
1076         .rename = ecryptfs_rename,
1077         .permission = ecryptfs_permission,
1078         .setattr = ecryptfs_setattr,
1079         .setxattr = ecryptfs_setxattr,
1080         .getxattr = ecryptfs_getxattr,
1081         .listxattr = ecryptfs_listxattr,
1082         .removexattr = ecryptfs_removexattr
1083 };
1084
1085 const struct inode_operations ecryptfs_main_iops = {
1086         .permission = ecryptfs_permission,
1087         .setattr = ecryptfs_setattr,
1088         .setxattr = ecryptfs_setxattr,
1089         .getxattr = ecryptfs_getxattr,
1090         .listxattr = ecryptfs_listxattr,
1091         .removexattr = ecryptfs_removexattr
1092 };