fs/ecryptfs/file.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) 2004-2006 International Business Machines Corp.
   7  *   Author(s): Michael A. Halcrow <mhalcrow@us.ibm.com>
   8  *              Michael C. Thompson <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/poll.h>
  28 #include <linux/mount.h>
  29 #include <linux/pagemap.h>
  30 #include <linux/security.h>
  31 #include <linux/smp_lock.h>
  32 #include <linux/compat.h>
  33 #include <linux/fs_stack.h>
  34 #include "ecryptfs_kernel.h"
  35
  36 /**
  37  * ecryptfs_llseek
  38  * @file: File we are seeking in
  39  * @offset: The offset to seek to
  40  * @origin: 2 - offset from i_size; 1 - offset from f_pos
  41  *
  42  * Returns the position we have seeked to, or negative on error
  43  */
  44 static loff_t ecryptfs_llseek(struct file *file, loff_t offset, int origin)
  45 {
  46         loff_t rv;
  47         loff_t new_end_pos;
  48         int rc;
  49         int expanding_file = 0;
  50         struct inode *inode = file->f_mapping->host;
  51
  52         /* If our offset is past the end of our file, we're going to
  53          * need to grow it so we have a valid length of 0's */
  54         new_end_pos = offset;
  55         switch (origin) {
  56         case 2:
  57                 new_end_pos += i_size_read(inode);
  58                 expanding_file = 1;
  59                 break;
  60         case 1:
  61                 new_end_pos += file->f_pos;
  62                 if (new_end_pos > i_size_read(inode)) {
  63                         ecryptfs_printk(KERN_DEBUG, "new_end_pos(=[0x%.16x]) "
  64                                         "> i_size_read(inode)(=[0x%.16x])\n",
  65                                         new_end_pos, i_size_read(inode));
  66                         expanding_file = 1;
  67                 }
  68                 break;
  69         default:
  70                 if (new_end_pos > i_size_read(inode)) {
  71                         ecryptfs_printk(KERN_DEBUG, "new_end_pos(=[0x%.16x]) "
  72                                         "> i_size_read(inode)(=[0x%.16x])\n",
  73                                         new_end_pos, i_size_read(inode));
  74                         expanding_file = 1;
  75                 }
  76         }
  77         ecryptfs_printk(KERN_DEBUG, "new_end_pos = [0x%.16x]\n", new_end_pos);
  78         if (expanding_file) {
  79                 rc = ecryptfs_truncate(file->f_path.dentry, new_end_pos);
  80                 if (rc) {
  81                         rv = rc;
  82                         ecryptfs_printk(KERN_ERR, "Error on attempt to "
  83                                         "truncate to (higher) offset [0x%.16x];"
  84                                         " rc = [%d]\n", new_end_pos, rc);
  85                         goto out;
  86                 }
  87         }
  88         rv = generic_file_llseek(file, offset, origin);
  89 out:
  90         return rv;
  91 }
  92
  93 /**
  94  * ecryptfs_read_update_atime
  95  *
  96  * generic_file_read updates the atime of upper layer inode.  But, it
  97  * doesn't give us a chance to update the atime of the lower layer
  98  * inode.  This function is a wrapper to generic_file_read.  It
  99  * updates the atime of the lower level inode if generic_file_read
 100  * returns without any errors. This is to be used only for file reads.
 101  * The function to be used for directory reads is ecryptfs_read.
 102  */
 103 static ssize_t ecryptfs_read_update_atime(struct kiocb *iocb,
 104                                 const struct iovec *iov,
 105                                 unsigned long nr_segs, loff_t pos)
 106 {
 107         int rc;
 108         struct dentry *lower_dentry;
 109         struct vfsmount *lower_vfsmount;
 110         struct file *file = iocb->ki_filp;
 111
 112         rc = generic_file_aio_read(iocb, iov, nr_segs, pos);
 113         /*
 114          * Even though this is a async interface, we need to wait
 115          * for IO to finish to update atime
 116          */
 117         if (-EIOCBQUEUED == rc)
 118                 rc = wait_on_sync_kiocb(iocb);
 119         if (rc >= 0) {
 120                 lower_dentry = ecryptfs_dentry_to_lower(file->f_path.dentry);
 121                 lower_vfsmount = ecryptfs_dentry_to_lower_mnt(file->f_path.dentry);
 122                 touch_atime(lower_vfsmount, lower_dentry);
 123         }
 124         return rc;
 125 }
 126
 127 struct ecryptfs_getdents_callback {
 128         void *dirent;
 129         struct dentry *dentry;
 130         filldir_t filldir;
 131         int err;
 132         int filldir_called;
 133         int entries_written;
 134 };
 135
 136 /* Inspired by generic filldir in fs/readir.c */
 137 static int
 138 ecryptfs_filldir(void *dirent, const char *name, int namelen, loff_t offset,
 139                  u64 ino, unsigned int d_type)
 140 {
 141         struct ecryptfs_crypt_stat *crypt_stat;
 142         struct ecryptfs_getdents_callback *buf =
 143             (struct ecryptfs_getdents_callback *)dirent;
 144         int rc;
 145         int decoded_length;
 146         char *decoded_name;
 147
 148         crypt_stat = ecryptfs_dentry_to_private(buf->dentry)->crypt_stat;
 149         buf->filldir_called++;
 150         decoded_length = ecryptfs_decode_filename(crypt_stat, name, namelen,
 151                                                   &decoded_name);
 152         if (decoded_length < 0) {
 153                 rc = decoded_length;
 154                 goto out;
 155         }
 156         rc = buf->filldir(buf->dirent, decoded_name, decoded_length, offset,
 157                           ino, d_type);
 158         kfree(decoded_name);
 159         if (rc >= 0)
 160                 buf->entries_written++;
 161 out:
 162         return rc;
 163 }
 164
 165 /**
 166  * ecryptfs_readdir
 167  * @file: The ecryptfs file struct
 168  * @dirent: Directory entry
 169  * @filldir: The filldir callback function
 170  */
 171 static int ecryptfs_readdir(struct file *file, void *dirent, filldir_t filldir)
 172 {
 173         int rc;
 174         struct file *lower_file;
 175         struct inode *inode;
 176         struct ecryptfs_getdents_callback buf;
 177
 178         lower_file = ecryptfs_file_to_lower(file);
 179         lower_file->f_pos = file->f_pos;
 180         inode = file->f_path.dentry->d_inode;
 181         memset(&buf, 0, sizeof(buf));
 182         buf.dirent = dirent;
 183         buf.dentry = file->f_path.dentry;
 184         buf.filldir = filldir;
 185 retry:
 186         buf.filldir_called = 0;
 187         buf.entries_written = 0;
 188         buf.err = 0;
 189         rc = vfs_readdir(lower_file, ecryptfs_filldir, (void *)&buf);
 190         if (buf.err)
 191                 rc = buf.err;
 192         if (buf.filldir_called && !buf.entries_written)
 193                 goto retry;
 194         file->f_pos = lower_file->f_pos;
 195         if (rc >= 0)
 196                 fsstack_copy_attr_atime(inode, lower_file->f_path.dentry->d_inode);
 197         return rc;
 198 }
 199
 200 struct kmem_cache *ecryptfs_file_info_cache;
 201
 202 int ecryptfs_open_lower_file(struct file **lower_file,
 203                              struct dentry *lower_dentry,
 204                              struct vfsmount *lower_mnt, int flags)
 205 {
 206         int rc = 0;
 207
 208         dget(lower_dentry);
 209         mntget(lower_mnt);
 210         *lower_file = dentry_open(lower_dentry, lower_mnt, flags);
 211         if (IS_ERR(*lower_file)) {
 212                 printk(KERN_ERR "Error opening lower file for lower_dentry "
 213                        "[0x%p], lower_mnt [0x%p], and flags [0x%x]\n",
 214                        lower_dentry, lower_mnt, flags);
 215                 rc = PTR_ERR(*lower_file);
 216                 *lower_file = NULL;
 217                 goto out;
 218         }
 219 out:
 220         return rc;
 221 }
 222
 223 int ecryptfs_close_lower_file(struct file *lower_file)
 224 {
 225         fput(lower_file);
 226         return 0;
 227 }
 228
 229 /**
 230  * ecryptfs_open
 231  * @inode: inode speciying file to open
 232  * @file: Structure to return filled in
 233  *
 234  * Opens the file specified by inode.
 235  *
 236  * Returns zero on success; non-zero otherwise
 237  */
 238 static int ecryptfs_open(struct inode *inode, struct file *file)
 239 {
 240         int rc = 0;
 241         struct ecryptfs_crypt_stat *crypt_stat = NULL;
 242         struct ecryptfs_mount_crypt_stat *mount_crypt_stat;
 243         struct dentry *ecryptfs_dentry = file->f_path.dentry;
 244         /* Private value of ecryptfs_dentry allocated in
 245          * ecryptfs_lookup() */
 246         struct dentry *lower_dentry = ecryptfs_dentry_to_lower(ecryptfs_dentry);
 247         struct inode *lower_inode = NULL;
 248         struct file *lower_file = NULL;
 249         struct vfsmount *lower_mnt;
 250         struct ecryptfs_file_info *file_info;
 251         int lower_flags;
 252
 253         /* Released in ecryptfs_release or end of function if failure */
 254         file_info = kmem_cache_alloc(ecryptfs_file_info_cache, GFP_KERNEL);
 255         ecryptfs_set_file_private(file, file_info);
 256         if (!file_info) {
 257                 ecryptfs_printk(KERN_ERR,
 258                                 "Error attempting to allocate memory\n");
 259                 rc = -ENOMEM;
 260                 goto out;
 261         }
 262         memset(file_info, 0, sizeof(*file_info));
 263         lower_dentry = ecryptfs_dentry_to_lower(ecryptfs_dentry);
 264         crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat;
 265         mount_crypt_stat = &ecryptfs_superblock_to_private(
 266                 ecryptfs_dentry->d_sb)->mount_crypt_stat;
 267         mutex_lock(&crypt_stat->cs_mutex);
 268         if (!ECRYPTFS_CHECK_FLAG(crypt_stat->flags, ECRYPTFS_POLICY_APPLIED)) {
 269                 ecryptfs_printk(KERN_DEBUG, "Setting flags for stat...\n");
 270                 /* Policy code enabled in future release */
 271                 ECRYPTFS_SET_FLAG(crypt_stat->flags, ECRYPTFS_POLICY_APPLIED);
 272                 ECRYPTFS_SET_FLAG(crypt_stat->flags, ECRYPTFS_ENCRYPTED);
 273         }
 274         mutex_unlock(&crypt_stat->cs_mutex);
 275         lower_flags = file->f_flags;
 276         if ((lower_flags & O_ACCMODE) == O_WRONLY)
 277                 lower_flags = (lower_flags & O_ACCMODE) | O_RDWR;
 278         if (file->f_flags & O_APPEND)
 279                 lower_flags &= ~O_APPEND;
 280         lower_mnt = ecryptfs_dentry_to_lower_mnt(ecryptfs_dentry);
 281         /* Corresponding fput() in ecryptfs_release() */
 282         if ((rc = ecryptfs_open_lower_file(&lower_file, lower_dentry, lower_mnt,
 283                                            lower_flags))) {
 284                 ecryptfs_printk(KERN_ERR, "Error opening lower file\n");
 285                 goto out_puts;
 286         }
 287         ecryptfs_set_file_lower(file, lower_file);
 288         /* Isn't this check the same as the one in lookup? */
 289         lower_inode = lower_dentry->d_inode;
 290         if (S_ISDIR(ecryptfs_dentry->d_inode->i_mode)) {
 291                 ecryptfs_printk(KERN_DEBUG, "This is a directory\n");
 292                 ECRYPTFS_CLEAR_FLAG(crypt_stat->flags, ECRYPTFS_ENCRYPTED);
 293                 rc = 0;
 294                 goto out;
 295         }
 296         mutex_lock(&crypt_stat->cs_mutex);
 297         if (i_size_read(lower_inode) < ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE) {
 298                 if (!(mount_crypt_stat->flags
 299                       & ECRYPTFS_PLAINTEXT_PASSTHROUGH_ENABLED)) {
 300                         rc = -EIO;
 301                         printk(KERN_WARNING "Attempt to read file that is "
 302                                "not in a valid eCryptfs format, and plaintext "
 303                                "passthrough mode is not enabled; returning "
 304                                "-EIO\n");
 305                         mutex_unlock(&crypt_stat->cs_mutex);
 306                         goto out_puts;
 307                 }
 308                 crypt_stat->flags &= ~(ECRYPTFS_ENCRYPTED);
 309                 rc = 0;
 310                 mutex_unlock(&crypt_stat->cs_mutex);
 311                 goto out;
 312         } else if (!ECRYPTFS_CHECK_FLAG(crypt_stat->flags,
 313                                         ECRYPTFS_POLICY_APPLIED)
 314                    || !ECRYPTFS_CHECK_FLAG(crypt_stat->flags,
 315                                            ECRYPTFS_KEY_VALID)) {
 316                 rc = ecryptfs_read_headers(ecryptfs_dentry, lower_file);
 317                 if (rc) {
 318                         ecryptfs_printk(KERN_DEBUG,
 319                                         "Valid headers not found\n");
 320                         if (!(mount_crypt_stat->flags
 321                               & ECRYPTFS_PLAINTEXT_PASSTHROUGH_ENABLED)) {
 322                                 rc = -EIO;
 323                                 printk(KERN_WARNING "Attempt to read file that "
 324                                        "is not in a valid eCryptfs format, "
 325                                        "and plaintext passthrough mode is not "
 326                                        "enabled; returning -EIO\n");
 327                                 mutex_unlock(&crypt_stat->cs_mutex);
 328                                 goto out_puts;
 329                         }
 330                         ECRYPTFS_CLEAR_FLAG(crypt_stat->flags,
 331                                             ECRYPTFS_ENCRYPTED);
 332                         rc = 0;
 333                         mutex_unlock(&crypt_stat->cs_mutex);
 334                         goto out;
 335                 }
 336         }
 337         mutex_unlock(&crypt_stat->cs_mutex);
 338         ecryptfs_printk(KERN_DEBUG, "inode w/ addr = [0x%p], i_ino = [0x%.16x] "
 339                         "size: [0x%.16x]\n", inode, inode->i_ino,
 340                         i_size_read(inode));
 341         ecryptfs_set_file_lower(file, lower_file);
 342         goto out;
 343 out_puts:
 344         mntput(lower_mnt);
 345         dput(lower_dentry);
 346         kmem_cache_free(ecryptfs_file_info_cache,
 347                         ecryptfs_file_to_private(file));
 348 out:
 349         return rc;
 350 }
 351
 352 static int ecryptfs_flush(struct file *file, fl_owner_t td)
 353 {
 354         int rc = 0;
 355         struct file *lower_file = NULL;
 356
 357         lower_file = ecryptfs_file_to_lower(file);
 358         if (lower_file->f_op && lower_file->f_op->flush)
 359                 rc = lower_file->f_op->flush(lower_file, td);
 360         return rc;
 361 }
 362
 363 static int ecryptfs_release(struct inode *inode, struct file *file)
 364 {
 365         struct file *lower_file = ecryptfs_file_to_lower(file);
 366         struct ecryptfs_file_info *file_info = ecryptfs_file_to_private(file);
 367         struct inode *lower_inode = ecryptfs_inode_to_lower(inode);
 368         int rc;
 369
 370         if ((rc = ecryptfs_close_lower_file(lower_file))) {
 371                 printk(KERN_ERR "Error closing lower_file\n");
 372                 goto out;
 373         }
 374         inode->i_blocks = lower_inode->i_blocks;
 375         kmem_cache_free(ecryptfs_file_info_cache, file_info);
 376 out:
 377         return rc;
 378 }
 379
 380 static int
 381 ecryptfs_fsync(struct file *file, struct dentry *dentry, int datasync)
 382 {
 383         struct file *lower_file = ecryptfs_file_to_lower(file);
 384         struct dentry *lower_dentry = ecryptfs_dentry_to_lower(dentry);
 385         struct inode *lower_inode = lower_dentry->d_inode;
 386         int rc = -EINVAL;
 387
 388         if (lower_inode->i_fop->fsync) {
 389                 mutex_lock(&lower_inode->i_mutex);
 390                 rc = lower_inode->i_fop->fsync(lower_file, lower_dentry,
 391                                                datasync);
 392                 mutex_unlock(&lower_inode->i_mutex);
 393         }
 394         return rc;
 395 }
 396
 397 static int ecryptfs_fasync(int fd, struct file *file, int flag)
 398 {
 399         int rc = 0;
 400         struct file *lower_file = NULL;
 401
 402         lower_file = ecryptfs_file_to_lower(file);
 403         if (lower_file->f_op && lower_file->f_op->fasync)
 404                 rc = lower_file->f_op->fasync(fd, lower_file, flag);
 405         return rc;
 406 }
 407
 408 static ssize_t ecryptfs_sendfile(struct file *file, loff_t * ppos,
 409                                  size_t count, read_actor_t actor, void *target)
 410 {
 411         struct file *lower_file = NULL;
 412         int rc = -EINVAL;
 413
 414         lower_file = ecryptfs_file_to_lower(file);
 415         if (lower_file->f_op && lower_file->f_op->sendfile)
 416                 rc = lower_file->f_op->sendfile(lower_file, ppos, count,
 417                                                 actor, target);
 418
 419         return rc;
 420 }
 421
 422 static int ecryptfs_ioctl(struct inode *inode, struct file *file,
 423                           unsigned int cmd, unsigned long arg);
 424
 425 const struct file_operations ecryptfs_dir_fops = {
 426         .readdir = ecryptfs_readdir,
 427         .ioctl = ecryptfs_ioctl,
 428         .mmap = generic_file_mmap,
 429         .open = ecryptfs_open,
 430         .flush = ecryptfs_flush,
 431         .release = ecryptfs_release,
 432         .fsync = ecryptfs_fsync,
 433         .fasync = ecryptfs_fasync,
 434         .sendfile = ecryptfs_sendfile,
 435 };
 436
 437 const struct file_operations ecryptfs_main_fops = {
 438         .llseek = ecryptfs_llseek,
 439         .read = do_sync_read,
 440         .aio_read = ecryptfs_read_update_atime,
 441         .write = do_sync_write,
 442         .aio_write = generic_file_aio_write,
 443         .readdir = ecryptfs_readdir,
 444         .ioctl = ecryptfs_ioctl,
 445         .mmap = generic_file_mmap,
 446         .open = ecryptfs_open,
 447         .flush = ecryptfs_flush,
 448         .release = ecryptfs_release,
 449         .fsync = ecryptfs_fsync,
 450         .fasync = ecryptfs_fasync,
 451         .sendfile = ecryptfs_sendfile,
 452 };
 453
 454 static int
 455 ecryptfs_ioctl(struct inode *inode, struct file *file, unsigned int cmd,
 456                unsigned long arg)
 457 {
 458         int rc = 0;
 459         struct file *lower_file = NULL;
 460
 461         if (ecryptfs_file_to_private(file))
 462                 lower_file = ecryptfs_file_to_lower(file);
 463         if (lower_file && lower_file->f_op && lower_file->f_op->ioctl)
 464                 rc = lower_file->f_op->ioctl(ecryptfs_inode_to_lower(inode),
 465                                              lower_file, cmd, arg);
 466         else
 467                 rc = -ENOTTY;
 468         return rc;
 469 }