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         dget(lower_dentry);
 480         lower_dir_dentry = lock_parent(lower_dentry);
 481         rc = vfs_unlink(lower_dir_inode, lower_dentry);
 482         if (rc) {
 483                 printk(KERN_ERR "Error in vfs_unlink; rc = [%d]\n", rc);
 484                 goto out_unlock;
 485         }
 486         fsstack_copy_attr_times(dir, lower_dir_inode);
 487         dentry->d_inode->i_nlink =
 488                 ecryptfs_inode_to_lower(dentry->d_inode)->i_nlink;
 489         dentry->d_inode->i_ctime = dir->i_ctime;
 490         d_drop(dentry);
 491 out_unlock:
 492         unlock_dir(lower_dir_dentry);
 493         dput(lower_dentry);
 494         return rc;
 495 }
 496
 497 static int ecryptfs_symlink(struct inode *dir, struct dentry *dentry,
 498                             const char *symname)
 499 {
 500         int rc;
 501         struct dentry *lower_dentry;
 502         struct dentry *lower_dir_dentry;
 503         char *encoded_symname;
 504         size_t encoded_symlen;
 505         struct ecryptfs_mount_crypt_stat *mount_crypt_stat = NULL;
 506
 507         lower_dentry = ecryptfs_dentry_to_lower(dentry);
 508         dget(lower_dentry);
 509         lower_dir_dentry = lock_parent(lower_dentry);
 510         mount_crypt_stat = &ecryptfs_superblock_to_private(
 511                 dir->i_sb)->mount_crypt_stat;
 512         rc = ecryptfs_encrypt_and_encode_filename(&encoded_symname,
 513                                                   &encoded_symlen,
 514                                                   NULL,
 515                                                   mount_crypt_stat, symname,
 516                                                   strlen(symname));
 517         if (rc)
 518                 goto out_lock;
 519         rc = vfs_symlink(lower_dir_dentry->d_inode, lower_dentry,
 520                          encoded_symname);
 521         kfree(encoded_symname);
 522         if (rc || !lower_dentry->d_inode)
 523                 goto out_lock;
 524         rc = ecryptfs_interpose(lower_dentry, dentry, dir->i_sb, 0);
 525         if (rc)
 526                 goto out_lock;
 527         fsstack_copy_attr_times(dir, lower_dir_dentry->d_inode);
 528         fsstack_copy_inode_size(dir, lower_dir_dentry->d_inode);
 529 out_lock:
 530         unlock_dir(lower_dir_dentry);
 531         dput(lower_dentry);
 532         if (!dentry->d_inode)
 533                 d_drop(dentry);
 534         return rc;
 535 }
 536
 537 static int ecryptfs_mkdir(struct inode *dir, struct dentry *dentry, int mode)
 538 {
 539         int rc;
 540         struct dentry *lower_dentry;
 541         struct dentry *lower_dir_dentry;
 542
 543         lower_dentry = ecryptfs_dentry_to_lower(dentry);
 544         lower_dir_dentry = lock_parent(lower_dentry);
 545         rc = vfs_mkdir(lower_dir_dentry->d_inode, lower_dentry, mode);
 546         if (rc || !lower_dentry->d_inode)
 547                 goto out;
 548         rc = ecryptfs_interpose(lower_dentry, dentry, dir->i_sb, 0);
 549         if (rc)
 550                 goto out;
 551         fsstack_copy_attr_times(dir, lower_dir_dentry->d_inode);
 552         fsstack_copy_inode_size(dir, lower_dir_dentry->d_inode);
 553         dir->i_nlink = lower_dir_dentry->d_inode->i_nlink;
 554 out:
 555         unlock_dir(lower_dir_dentry);
 556         if (!dentry->d_inode)
 557                 d_drop(dentry);
 558         return rc;
 559 }
 560
 561 static int ecryptfs_rmdir(struct inode *dir, struct dentry *dentry)
 562 {
 563         struct dentry *lower_dentry;
 564         struct dentry *lower_dir_dentry;
 565         int rc;
 566
 567         lower_dentry = ecryptfs_dentry_to_lower(dentry);
 568         dget(dentry);
 569         lower_dir_dentry = lock_parent(lower_dentry);
 570         dget(lower_dentry);
 571         rc = vfs_rmdir(lower_dir_dentry->d_inode, lower_dentry);
 572         dput(lower_dentry);
 573         if (!rc)
 574                 d_delete(lower_dentry);
 575         fsstack_copy_attr_times(dir, lower_dir_dentry->d_inode);
 576         dir->i_nlink = lower_dir_dentry->d_inode->i_nlink;
 577         unlock_dir(lower_dir_dentry);
 578         if (!rc)
 579                 d_drop(dentry);
 580         dput(dentry);
 581         return rc;
 582 }
 583
 584 static int
 585 ecryptfs_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev)
 586 {
 587         int rc;
 588         struct dentry *lower_dentry;
 589         struct dentry *lower_dir_dentry;
 590
 591         lower_dentry = ecryptfs_dentry_to_lower(dentry);
 592         lower_dir_dentry = lock_parent(lower_dentry);
 593         rc = vfs_mknod(lower_dir_dentry->d_inode, lower_dentry, mode, dev);
 594         if (rc || !lower_dentry->d_inode)
 595                 goto out;
 596         rc = ecryptfs_interpose(lower_dentry, dentry, dir->i_sb, 0);
 597         if (rc)
 598                 goto out;
 599         fsstack_copy_attr_times(dir, lower_dir_dentry->d_inode);
 600         fsstack_copy_inode_size(dir, lower_dir_dentry->d_inode);
 601 out:
 602         unlock_dir(lower_dir_dentry);
 603         if (!dentry->d_inode)
 604                 d_drop(dentry);
 605         return rc;
 606 }
 607
 608 static int
 609 ecryptfs_rename(struct inode *old_dir, struct dentry *old_dentry,
 610                 struct inode *new_dir, struct dentry *new_dentry)
 611 {
 612         int rc;
 613         struct dentry *lower_old_dentry;
 614         struct dentry *lower_new_dentry;
 615         struct dentry *lower_old_dir_dentry;
 616         struct dentry *lower_new_dir_dentry;
 617
 618         lower_old_dentry = ecryptfs_dentry_to_lower(old_dentry);
 619         lower_new_dentry = ecryptfs_dentry_to_lower(new_dentry);
 620         dget(lower_old_dentry);
 621         dget(lower_new_dentry);
 622         lower_old_dir_dentry = dget_parent(lower_old_dentry);
 623         lower_new_dir_dentry = dget_parent(lower_new_dentry);
 624         lock_rename(lower_old_dir_dentry, lower_new_dir_dentry);
 625         rc = vfs_rename(lower_old_dir_dentry->d_inode, lower_old_dentry,
 626                         lower_new_dir_dentry->d_inode, lower_new_dentry);
 627         if (rc)
 628                 goto out_lock;
 629         fsstack_copy_attr_all(new_dir, lower_new_dir_dentry->d_inode);
 630         if (new_dir != old_dir)
 631                 fsstack_copy_attr_all(old_dir, lower_old_dir_dentry->d_inode);
 632 out_lock:
 633         unlock_rename(lower_old_dir_dentry, lower_new_dir_dentry);
 634         dput(lower_new_dentry->d_parent);
 635         dput(lower_old_dentry->d_parent);
 636         dput(lower_new_dentry);
 637         dput(lower_old_dentry);
 638         return rc;
 639 }
 640
 641 static int
 642 ecryptfs_readlink(struct dentry *dentry, char __user *buf, int bufsiz)
 643 {
 644         char *lower_buf;
 645         size_t lower_bufsiz;
 646         struct dentry *lower_dentry;
 647         struct ecryptfs_mount_crypt_stat *mount_crypt_stat;
 648         char *plaintext_name;
 649         size_t plaintext_name_size;
 650         mm_segment_t old_fs;
 651         int rc;
 652
 653         lower_dentry = ecryptfs_dentry_to_lower(dentry);
 654         if (!lower_dentry->d_inode->i_op->readlink) {
 655                 rc = -EINVAL;
 656                 goto out;
 657         }
 658         mount_crypt_stat = &ecryptfs_superblock_to_private(
 659                                                 dentry->d_sb)->mount_crypt_stat;
 660         /*
 661          * If the lower filename is encrypted, it will result in a significantly
 662          * longer name.  If needed, truncate the name after decode and decrypt.
 663          */
 664         if (mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES)
 665                 lower_bufsiz = PATH_MAX;
 666         else
 667                 lower_bufsiz = bufsiz;
 668         /* Released in this function */
 669         lower_buf = kmalloc(lower_bufsiz, GFP_KERNEL);
 670         if (lower_buf == NULL) {
 671                 printk(KERN_ERR "%s: Out of memory whilst attempting to "
 672                        "kmalloc [%zd] bytes\n", __func__, lower_bufsiz);
 673                 rc = -ENOMEM;
 674                 goto out;
 675         }
 676         old_fs = get_fs();
 677         set_fs(get_ds());
 678         rc = lower_dentry->d_inode->i_op->readlink(lower_dentry,
 679                                                    (char __user *)lower_buf,
 680                                                    lower_bufsiz);
 681         set_fs(old_fs);
 682         if (rc >= 0) {
 683                 rc = ecryptfs_decode_and_decrypt_filename(&plaintext_name,
 684                                                           &plaintext_name_size,
 685                                                           dentry, lower_buf,
 686                                                           rc);
 687                 if (rc) {
 688                         printk(KERN_ERR "%s: Error attempting to decode and "
 689                                "decrypt filename; rc = [%d]\n", __func__,
 690                                 rc);
 691                         goto out_free_lower_buf;
 692                 }
 693                 /* Check for bufsiz <= 0 done in sys_readlinkat() */
 694                 rc = copy_to_user(buf, plaintext_name,
 695                                   min((size_t) bufsiz, plaintext_name_size));
 696                 if (rc)
 697                         rc = -EFAULT;
 698                 else
 699                         rc = plaintext_name_size;
 700                 kfree(plaintext_name);
 701                 fsstack_copy_attr_atime(dentry->d_inode, lower_dentry->d_inode);
 702         }
 703 out_free_lower_buf:
 704         kfree(lower_buf);
 705 out:
 706         return rc;
 707 }
 708
 709 static void *ecryptfs_follow_link(struct dentry *dentry, struct nameidata *nd)
 710 {
 711         char *buf;
 712         int len = PAGE_SIZE, rc;
 713         mm_segment_t old_fs;
 714
 715         /* Released in ecryptfs_put_link(); only release here on error */
 716         buf = kmalloc(len, GFP_KERNEL);
 717         if (!buf) {
 718                 buf = ERR_PTR(-ENOMEM);
 719                 goto out;
 720         }
 721         old_fs = get_fs();
 722         set_fs(get_ds());
 723         rc = dentry->d_inode->i_op->readlink(dentry, (char __user *)buf, len);
 724         set_fs(old_fs);
 725         if (rc < 0) {
 726                 kfree(buf);
 727                 buf = ERR_PTR(rc);
 728         } else
 729                 buf[rc] = '\0';
 730 out:
 731         nd_set_link(nd, buf);
 732         return NULL;
 733 }
 734
 735 static void
 736 ecryptfs_put_link(struct dentry *dentry, struct nameidata *nd, void *ptr)
 737 {
 738         char *buf = nd_get_link(nd);
 739         if (!IS_ERR(buf)) {
 740                 /* Free the char* */
 741                 kfree(buf);
 742         }
 743 }
 744
 745 /**
 746  * upper_size_to_lower_size
 747  * @crypt_stat: Crypt_stat associated with file
 748  * @upper_size: Size of the upper file
 749  *
 750  * Calculate the required size of the lower file based on the
 751  * specified size of the upper file. This calculation is based on the
 752  * number of headers in the underlying file and the extent size.
 753  *
 754  * Returns Calculated size of the lower file.
 755  */
 756 static loff_t
 757 upper_size_to_lower_size(struct ecryptfs_crypt_stat *crypt_stat,
 758                          loff_t upper_size)
 759 {
 760         loff_t lower_size;
 761
 762         lower_size = crypt_stat->num_header_bytes_at_front;
 763         if (upper_size != 0) {
 764                 loff_t num_extents;
 765
 766                 num_extents = upper_size >> crypt_stat->extent_shift;
 767                 if (upper_size & ~crypt_stat->extent_mask)
 768                         num_extents++;
 769                 lower_size += (num_extents * crypt_stat->extent_size);
 770         }
 771         return lower_size;
 772 }
 773
 774 /**
 775  * ecryptfs_truncate
 776  * @dentry: The ecryptfs layer dentry
 777  * @new_length: The length to expand the file to
 778  *
 779  * Function to handle truncations modifying the size of the file. Note
 780  * that the file sizes are interpolated. When expanding, we are simply
 781  * writing strings of 0's out. When truncating, we need to modify the
 782  * underlying file size according to the page index interpolations.
 783  *
 784  * Returns zero on success; non-zero otherwise
 785  */
 786 int ecryptfs_truncate(struct dentry *dentry, loff_t new_length)
 787 {
 788         int rc = 0;
 789         struct inode *inode = dentry->d_inode;
 790         struct dentry *lower_dentry;
 791         struct file fake_ecryptfs_file;
 792         struct ecryptfs_crypt_stat *crypt_stat;
 793         loff_t i_size = i_size_read(inode);
 794         loff_t lower_size_before_truncate;
 795         loff_t lower_size_after_truncate;
 796
 797         if (unlikely((new_length == i_size)))
 798                 goto out;
 799         crypt_stat = &ecryptfs_inode_to_private(dentry->d_inode)->crypt_stat;
 800         /* Set up a fake ecryptfs file, this is used to interface with
 801          * the file in the underlying filesystem so that the
 802          * truncation has an effect there as well. */
 803         memset(&fake_ecryptfs_file, 0, sizeof(fake_ecryptfs_file));
 804         fake_ecryptfs_file.f_path.dentry = dentry;
 805         /* Released at out_free: label */
 806         ecryptfs_set_file_private(&fake_ecryptfs_file,
 807                                   kmem_cache_alloc(ecryptfs_file_info_cache,
 808                                                    GFP_KERNEL));
 809         if (unlikely(!ecryptfs_file_to_private(&fake_ecryptfs_file))) {
 810                 rc = -ENOMEM;
 811                 goto out;
 812         }
 813         lower_dentry = ecryptfs_dentry_to_lower(dentry);
 814         ecryptfs_set_file_lower(
 815                 &fake_ecryptfs_file,
 816                 ecryptfs_inode_to_private(dentry->d_inode)->lower_file);
 817         /* Switch on growing or shrinking file */
 818         if (new_length > i_size) {
 819                 char zero[] = { 0x00 };
 820
 821                 /* Write a single 0 at the last position of the file;
 822                  * this triggers code that will fill in 0's throughout
 823                  * the intermediate portion of the previous end of the
 824                  * file and the new and of the file */
 825                 rc = ecryptfs_write(&fake_ecryptfs_file, zero,
 826                                     (new_length - 1), 1);
 827         } else { /* new_length < i_size_read(inode) */
 828                 /* We're chopping off all the pages down do the page
 829                  * in which new_length is located. Fill in the end of
 830                  * that page from (new_length & ~PAGE_CACHE_MASK) to
 831                  * PAGE_CACHE_SIZE with zeros. */
 832                 size_t num_zeros = (PAGE_CACHE_SIZE
 833                                     - (new_length & ~PAGE_CACHE_MASK));
 834
 835                 if (!(crypt_stat->flags & ECRYPTFS_ENCRYPTED)) {
 836                         rc = vmtruncate(inode, new_length);
 837                         if (rc)
 838                                 goto out_free;
 839                         rc = vmtruncate(lower_dentry->d_inode, new_length);
 840                         goto out_free;
 841                 }
 842                 if (num_zeros) {
 843                         char *zeros_virt;
 844
 845                         zeros_virt = kzalloc(num_zeros, GFP_KERNEL);
 846                         if (!zeros_virt) {
 847                                 rc = -ENOMEM;
 848                                 goto out_free;
 849                         }
 850                         rc = ecryptfs_write(&fake_ecryptfs_file, zeros_virt,
 851                                             new_length, num_zeros);
 852                         kfree(zeros_virt);
 853                         if (rc) {
 854                                 printk(KERN_ERR "Error attempting to zero out "
 855                                        "the remainder of the end page on "
 856                                        "reducing truncate; rc = [%d]\n", rc);
 857                                 goto out_free;
 858                         }
 859                 }
 860                 vmtruncate(inode, new_length);
 861                 rc = ecryptfs_write_inode_size_to_metadata(inode);
 862                 if (rc) {
 863                         printk(KERN_ERR "Problem with "
 864                                "ecryptfs_write_inode_size_to_metadata; "
 865                                "rc = [%d]\n", rc);
 866                         goto out_free;
 867                 }
 868                 /* We are reducing the size of the ecryptfs file, and need to
 869                  * know if we need to reduce the size of the lower file. */
 870                 lower_size_before_truncate =
 871                     upper_size_to_lower_size(crypt_stat, i_size);
 872                 lower_size_after_truncate =
 873                     upper_size_to_lower_size(crypt_stat, new_length);
 874                 if (lower_size_after_truncate < lower_size_before_truncate)
 875                         vmtruncate(lower_dentry->d_inode,
 876                                    lower_size_after_truncate);
 877         }
 878 out_free:
 879         if (ecryptfs_file_to_private(&fake_ecryptfs_file))
 880                 kmem_cache_free(ecryptfs_file_info_cache,
 881                                 ecryptfs_file_to_private(&fake_ecryptfs_file));
 882 out:
 883         return rc;
 884 }
 885
 886 static int
 887 ecryptfs_permission(struct inode *inode, int mask)
 888 {
 889         return inode_permission(ecryptfs_inode_to_lower(inode), mask);
 890 }
 891
 892 /**
 893  * ecryptfs_setattr
 894  * @dentry: dentry handle to the inode to modify
 895  * @ia: Structure with flags of what to change and values
 896  *
 897  * Updates the metadata of an inode. If the update is to the size
 898  * i.e. truncation, then ecryptfs_truncate will handle the size modification
 899  * of both the ecryptfs inode and the lower inode.
 900  *
 901  * All other metadata changes will be passed right to the lower filesystem,
 902  * and we will just update our inode to look like the lower.
 903  */
 904 static int ecryptfs_setattr(struct dentry *dentry, struct iattr *ia)
 905 {
 906         int rc = 0;
 907         struct dentry *lower_dentry;
 908         struct inode *inode;
 909         struct inode *lower_inode;
 910         struct ecryptfs_crypt_stat *crypt_stat;
 911
 912         crypt_stat = &ecryptfs_inode_to_private(dentry->d_inode)->crypt_stat;
 913         if (!(crypt_stat->flags & ECRYPTFS_STRUCT_INITIALIZED))
 914                 ecryptfs_init_crypt_stat(crypt_stat);
 915         inode = dentry->d_inode;
 916         lower_inode = ecryptfs_inode_to_lower(inode);
 917         lower_dentry = ecryptfs_dentry_to_lower(dentry);
 918         mutex_lock(&crypt_stat->cs_mutex);
 919         if (S_ISDIR(dentry->d_inode->i_mode))
 920                 crypt_stat->flags &= ~(ECRYPTFS_ENCRYPTED);
 921         else if (S_ISREG(dentry->d_inode->i_mode)
 922                  && (!(crypt_stat->flags & ECRYPTFS_POLICY_APPLIED)
 923                      || !(crypt_stat->flags & ECRYPTFS_KEY_VALID))) {
 924                 struct ecryptfs_mount_crypt_stat *mount_crypt_stat;
 925
 926                 mount_crypt_stat = &ecryptfs_superblock_to_private(
 927                         dentry->d_sb)->mount_crypt_stat;
 928                 rc = ecryptfs_read_metadata(dentry);
 929                 if (rc) {
 930                         if (!(mount_crypt_stat->flags
 931                               & ECRYPTFS_PLAINTEXT_PASSTHROUGH_ENABLED)) {
 932                                 rc = -EIO;
 933                                 printk(KERN_WARNING "Either the lower file "
 934                                        "is not in a valid eCryptfs format, "
 935                                        "or the key could not be retrieved. "
 936                                        "Plaintext passthrough mode is not "
 937                                        "enabled; returning -EIO\n");
 938                                 mutex_unlock(&crypt_stat->cs_mutex);
 939                                 goto out;
 940                         }
 941                         rc = 0;
 942                         crypt_stat->flags &= ~(ECRYPTFS_ENCRYPTED);
 943                 }
 944         }
 945         mutex_unlock(&crypt_stat->cs_mutex);
 946         if (ia->ia_valid & ATTR_SIZE) {
 947                 ecryptfs_printk(KERN_DEBUG,
 948                                 "ia->ia_valid = [0x%x] ATTR_SIZE" " = [0x%x]\n",
 949                                 ia->ia_valid, ATTR_SIZE);
 950                 rc = ecryptfs_truncate(dentry, ia->ia_size);
 951                 /* ecryptfs_truncate handles resizing of the lower file */
 952                 ia->ia_valid &= ~ATTR_SIZE;
 953                 ecryptfs_printk(KERN_DEBUG, "ia->ia_valid = [%x]\n",
 954                                 ia->ia_valid);
 955                 if (rc < 0)
 956                         goto out;
 957         }
 958
 959         /*
 960          * mode change is for clearing setuid/setgid bits. Allow lower fs
 961          * to interpret this in its own way.
 962          */
 963         if (ia->ia_valid & (ATTR_KILL_SUID | ATTR_KILL_SGID))
 964                 ia->ia_valid &= ~ATTR_MODE;
 965
 966         mutex_lock(&lower_dentry->d_inode->i_mutex);
 967         rc = notify_change(lower_dentry, ia);
 968         mutex_unlock(&lower_dentry->d_inode->i_mutex);
 969 out:
 970         fsstack_copy_attr_all(inode, lower_inode);
 971         return rc;
 972 }
 973
 974 int
 975 ecryptfs_setxattr(struct dentry *dentry, const char *name, const void *value,
 976                   size_t size, int flags)
 977 {
 978         int rc = 0;
 979         struct dentry *lower_dentry;
 980
 981         lower_dentry = ecryptfs_dentry_to_lower(dentry);
 982         if (!lower_dentry->d_inode->i_op->setxattr) {
 983                 rc = -ENOSYS;
 984                 goto out;
 985         }
 986         mutex_lock(&lower_dentry->d_inode->i_mutex);
 987         rc = lower_dentry->d_inode->i_op->setxattr(lower_dentry, name, value,
 988                                                    size, flags);
 989         mutex_unlock(&lower_dentry->d_inode->i_mutex);
 990 out:
 991         return rc;
 992 }
 993
 994 ssize_t
 995 ecryptfs_getxattr_lower(struct dentry *lower_dentry, const char *name,
 996                         void *value, size_t size)
 997 {
 998         int rc = 0;
 999
1000         if (!lower_dentry->d_inode->i_op->getxattr) {
1001                 rc = -ENOSYS;
1002                 goto out;
1003         }
1004         mutex_lock(&lower_dentry->d_inode->i_mutex);
1005         rc = lower_dentry->d_inode->i_op->getxattr(lower_dentry, name, value,
1006                                                    size);
1007         mutex_unlock(&lower_dentry->d_inode->i_mutex);
1008 out:
1009         return rc;
1010 }
1011
1012 static ssize_t
1013 ecryptfs_getxattr(struct dentry *dentry, const char *name, void *value,
1014                   size_t size)
1015 {
1016         return ecryptfs_getxattr_lower(ecryptfs_dentry_to_lower(dentry), name,
1017                                        value, size);
1018 }
1019
1020 static ssize_t
1021 ecryptfs_listxattr(struct dentry *dentry, char *list, size_t size)
1022 {
1023         int rc = 0;
1024         struct dentry *lower_dentry;
1025
1026         lower_dentry = ecryptfs_dentry_to_lower(dentry);
1027         if (!lower_dentry->d_inode->i_op->listxattr) {
1028                 rc = -ENOSYS;
1029                 goto out;
1030         }
1031         mutex_lock(&lower_dentry->d_inode->i_mutex);
1032         rc = lower_dentry->d_inode->i_op->listxattr(lower_dentry, list, size);
1033         mutex_unlock(&lower_dentry->d_inode->i_mutex);
1034 out:
1035         return rc;
1036 }
1037
1038 static int ecryptfs_removexattr(struct dentry *dentry, const char *name)
1039 {
1040         int rc = 0;
1041         struct dentry *lower_dentry;
1042
1043         lower_dentry = ecryptfs_dentry_to_lower(dentry);
1044         if (!lower_dentry->d_inode->i_op->removexattr) {
1045                 rc = -ENOSYS;
1046                 goto out;
1047         }
1048         mutex_lock(&lower_dentry->d_inode->i_mutex);
1049         rc = lower_dentry->d_inode->i_op->removexattr(lower_dentry, name);
1050         mutex_unlock(&lower_dentry->d_inode->i_mutex);
1051 out:
1052         return rc;
1053 }
1054
1055 int ecryptfs_inode_test(struct inode *inode, void *candidate_lower_inode)
1056 {
1057         if ((ecryptfs_inode_to_lower(inode)
1058              == (struct inode *)candidate_lower_inode))
1059                 return 1;
1060         else
1061                 return 0;
1062 }
1063
1064 int ecryptfs_inode_set(struct inode *inode, void *lower_inode)
1065 {
1066         ecryptfs_init_inode(inode, (struct inode *)lower_inode);
1067         return 0;
1068 }
1069
1070 const struct inode_operations ecryptfs_symlink_iops = {
1071         .readlink = ecryptfs_readlink,
1072         .follow_link = ecryptfs_follow_link,
1073         .put_link = ecryptfs_put_link,
1074         .permission = ecryptfs_permission,
1075         .setattr = ecryptfs_setattr,
1076         .setxattr = ecryptfs_setxattr,
1077         .getxattr = ecryptfs_getxattr,
1078         .listxattr = ecryptfs_listxattr,
1079         .removexattr = ecryptfs_removexattr
1080 };
1081
1082 const struct inode_operations ecryptfs_dir_iops = {
1083         .create = ecryptfs_create,
1084         .lookup = ecryptfs_lookup,
1085         .link = ecryptfs_link,
1086         .unlink = ecryptfs_unlink,
1087         .symlink = ecryptfs_symlink,
1088         .mkdir = ecryptfs_mkdir,
1089         .rmdir = ecryptfs_rmdir,
1090         .mknod = ecryptfs_mknod,
1091         .rename = ecryptfs_rename,
1092         .permission = ecryptfs_permission,
1093         .setattr = ecryptfs_setattr,
1094         .setxattr = ecryptfs_setxattr,
1095         .getxattr = ecryptfs_getxattr,
1096         .listxattr = ecryptfs_listxattr,
1097         .removexattr = ecryptfs_removexattr
1098 };
1099
1100 const struct inode_operations ecryptfs_main_iops = {
1101         .permission = ecryptfs_permission,
1102         .setattr = ecryptfs_setattr,
1103         .setxattr = ecryptfs_setxattr,
1104         .getxattr = ecryptfs_getxattr,
1105         .listxattr = ecryptfs_listxattr,
1106         .removexattr = ecryptfs_removexattr
1107 };