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) 2004-2007 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         flags |= O_LARGEFILE;
 209         dget(lower_dentry);
 210         mntget(lower_mnt);
 211         *lower_file = dentry_open(lower_dentry, lower_mnt, flags);
 212         if (IS_ERR(*lower_file)) {
 213                 printk(KERN_ERR "Error opening lower file for lower_dentry "
 214                        "[0x%p], lower_mnt [0x%p], and flags [0x%x]\n",
 215                        lower_dentry, lower_mnt, flags);
 216                 rc = PTR_ERR(*lower_file);
 217                 *lower_file = NULL;
 218                 goto out;
 219         }
 220 out:
 221         return rc;
 222 }
 223
 224 int ecryptfs_close_lower_file(struct file *lower_file)
 225 {
 226         fput(lower_file);
 227         return 0;
 228 }
 229
 230 /**
 231  * ecryptfs_open
 232  * @inode: inode speciying file to open
 233  * @file: Structure to return filled in
 234  *
 235  * Opens the file specified by inode.
 236  *
 237  * Returns zero on success; non-zero otherwise
 238  */
 239 static int ecryptfs_open(struct inode *inode, struct file *file)
 240 {
 241         int rc = 0;
 242         struct ecryptfs_crypt_stat *crypt_stat = NULL;
 243         struct ecryptfs_mount_crypt_stat *mount_crypt_stat;
 244         struct dentry *ecryptfs_dentry = file->f_path.dentry;
 245         /* Private value of ecryptfs_dentry allocated in
 246          * ecryptfs_lookup() */
 247         struct dentry *lower_dentry = ecryptfs_dentry_to_lower(ecryptfs_dentry);
 248         struct inode *lower_inode = NULL;
 249         struct file *lower_file = NULL;
 250         struct vfsmount *lower_mnt;
 251         struct ecryptfs_file_info *file_info;
 252         int lower_flags;
 253
 254         mount_crypt_stat = &ecryptfs_superblock_to_private(
 255                 ecryptfs_dentry->d_sb)->mount_crypt_stat;
 256         if ((mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED)
 257             && ((file->f_flags & O_WRONLY) || (file->f_flags & O_RDWR)
 258                 || (file->f_flags & O_CREAT) || (file->f_flags & O_TRUNC)
 259                 || (file->f_flags & O_APPEND))) {
 260                 printk(KERN_WARNING "Mount has encrypted view enabled; "
 261                        "files may only be read\n");
 262                 rc = -EPERM;
 263                 goto out;
 264         }
 265         /* Released in ecryptfs_release or end of function if failure */
 266         file_info = kmem_cache_zalloc(ecryptfs_file_info_cache, GFP_KERNEL);
 267         ecryptfs_set_file_private(file, file_info);
 268         if (!file_info) {
 269                 ecryptfs_printk(KERN_ERR,
 270                                 "Error attempting to allocate memory\n");
 271                 rc = -ENOMEM;
 272                 goto out;
 273         }
 274         lower_dentry = ecryptfs_dentry_to_lower(ecryptfs_dentry);
 275         crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat;
 276         mutex_lock(&crypt_stat->cs_mutex);
 277         if (!(crypt_stat->flags & ECRYPTFS_POLICY_APPLIED)) {
 278                 ecryptfs_printk(KERN_DEBUG, "Setting flags for stat...\n");
 279                 /* Policy code enabled in future release */
 280                 crypt_stat->flags |= ECRYPTFS_POLICY_APPLIED;
 281                 crypt_stat->flags |= ECRYPTFS_ENCRYPTED;
 282         }
 283         mutex_unlock(&crypt_stat->cs_mutex);
 284         lower_flags = file->f_flags;
 285         if ((lower_flags & O_ACCMODE) == O_WRONLY)
 286                 lower_flags = (lower_flags & O_ACCMODE) | O_RDWR;
 287         if (file->f_flags & O_APPEND)
 288                 lower_flags &= ~O_APPEND;
 289         lower_mnt = ecryptfs_dentry_to_lower_mnt(ecryptfs_dentry);
 290         /* Corresponding fput() in ecryptfs_release() */
 291         if ((rc = ecryptfs_open_lower_file(&lower_file, lower_dentry, lower_mnt,
 292                                            lower_flags))) {
 293                 ecryptfs_printk(KERN_ERR, "Error opening lower file\n");
 294                 goto out_puts;
 295         }
 296         ecryptfs_set_file_lower(file, lower_file);
 297         /* Isn't this check the same as the one in lookup? */
 298         lower_inode = lower_dentry->d_inode;
 299         if (S_ISDIR(ecryptfs_dentry->d_inode->i_mode)) {
 300                 ecryptfs_printk(KERN_DEBUG, "This is a directory\n");
 301                 crypt_stat->flags &= ~(ECRYPTFS_ENCRYPTED);
 302                 rc = 0;
 303                 goto out;
 304         }
 305         mutex_lock(&crypt_stat->cs_mutex);
 306         if (!(crypt_stat->flags & ECRYPTFS_POLICY_APPLIED)
 307             || !(crypt_stat->flags & ECRYPTFS_KEY_VALID)) {
 308                 rc = ecryptfs_read_metadata(ecryptfs_dentry, lower_file);
 309                 if (rc) {
 310                         ecryptfs_printk(KERN_DEBUG,
 311                                         "Valid headers not found\n");
 312                         if (!(mount_crypt_stat->flags
 313                               & ECRYPTFS_PLAINTEXT_PASSTHROUGH_ENABLED)) {
 314                                 rc = -EIO;
 315                                 printk(KERN_WARNING "Attempt to read file that "
 316                                        "is not in a valid eCryptfs format, "
 317                                        "and plaintext passthrough mode is not "
 318                                        "enabled; returning -EIO\n");
 319                                 mutex_unlock(&crypt_stat->cs_mutex);
 320                                 goto out_puts;
 321                         }
 322                         rc = 0;
 323                         crypt_stat->flags &= ~(ECRYPTFS_ENCRYPTED);
 324                         mutex_unlock(&crypt_stat->cs_mutex);
 325                         goto out;
 326                 }
 327         }
 328         mutex_unlock(&crypt_stat->cs_mutex);
 329         ecryptfs_printk(KERN_DEBUG, "inode w/ addr = [0x%p], i_ino = [0x%.16x] "
 330                         "size: [0x%.16x]\n", inode, inode->i_ino,
 331                         i_size_read(inode));
 332         ecryptfs_set_file_lower(file, lower_file);
 333         goto out;
 334 out_puts:
 335         mntput(lower_mnt);
 336         dput(lower_dentry);
 337         kmem_cache_free(ecryptfs_file_info_cache,
 338                         ecryptfs_file_to_private(file));
 339 out:
 340         return rc;
 341 }
 342
 343 static int ecryptfs_flush(struct file *file, fl_owner_t td)
 344 {
 345         int rc = 0;
 346         struct file *lower_file = NULL;
 347
 348         lower_file = ecryptfs_file_to_lower(file);
 349         if (lower_file->f_op && lower_file->f_op->flush)
 350                 rc = lower_file->f_op->flush(lower_file, td);
 351         return rc;
 352 }
 353
 354 static int ecryptfs_release(struct inode *inode, struct file *file)
 355 {
 356         struct file *lower_file = ecryptfs_file_to_lower(file);
 357         struct ecryptfs_file_info *file_info = ecryptfs_file_to_private(file);
 358         struct inode *lower_inode = ecryptfs_inode_to_lower(inode);
 359         int rc;
 360
 361         if ((rc = ecryptfs_close_lower_file(lower_file))) {
 362                 printk(KERN_ERR "Error closing lower_file\n");
 363                 goto out;
 364         }
 365         inode->i_blocks = lower_inode->i_blocks;
 366         kmem_cache_free(ecryptfs_file_info_cache, file_info);
 367 out:
 368         return rc;
 369 }
 370
 371 static int
 372 ecryptfs_fsync(struct file *file, struct dentry *dentry, int datasync)
 373 {
 374         struct file *lower_file = ecryptfs_file_to_lower(file);
 375         struct dentry *lower_dentry = ecryptfs_dentry_to_lower(dentry);
 376         struct inode *lower_inode = lower_dentry->d_inode;
 377         int rc = -EINVAL;
 378
 379         if (lower_inode->i_fop->fsync) {
 380                 mutex_lock(&lower_inode->i_mutex);
 381                 rc = lower_inode->i_fop->fsync(lower_file, lower_dentry,
 382                                                datasync);
 383                 mutex_unlock(&lower_inode->i_mutex);
 384         }
 385         return rc;
 386 }
 387
 388 static int ecryptfs_fasync(int fd, struct file *file, int flag)
 389 {
 390         int rc = 0;
 391         struct file *lower_file = NULL;
 392
 393         lower_file = ecryptfs_file_to_lower(file);
 394         if (lower_file->f_op && lower_file->f_op->fasync)
 395                 rc = lower_file->f_op->fasync(fd, lower_file, flag);
 396         return rc;
 397 }
 398
 399 static ssize_t ecryptfs_sendfile(struct file *file, loff_t * ppos,
 400                                  size_t count, read_actor_t actor, void *target)
 401 {
 402         struct file *lower_file = NULL;
 403         int rc = -EINVAL;
 404
 405         lower_file = ecryptfs_file_to_lower(file);
 406         if (lower_file->f_op && lower_file->f_op->sendfile)
 407                 rc = lower_file->f_op->sendfile(lower_file, ppos, count,
 408                                                 actor, target);
 409
 410         return rc;
 411 }
 412
 413 static int ecryptfs_ioctl(struct inode *inode, struct file *file,
 414                           unsigned int cmd, unsigned long arg);
 415
 416 const struct file_operations ecryptfs_dir_fops = {
 417         .readdir = ecryptfs_readdir,
 418         .ioctl = ecryptfs_ioctl,
 419         .mmap = generic_file_mmap,
 420         .open = ecryptfs_open,
 421         .flush = ecryptfs_flush,
 422         .release = ecryptfs_release,
 423         .fsync = ecryptfs_fsync,
 424         .fasync = ecryptfs_fasync,
 425         .sendfile = ecryptfs_sendfile,
 426 };
 427
 428 const struct file_operations ecryptfs_main_fops = {
 429         .llseek = ecryptfs_llseek,
 430         .read = do_sync_read,
 431         .aio_read = ecryptfs_read_update_atime,
 432         .write = do_sync_write,
 433         .aio_write = generic_file_aio_write,
 434         .readdir = ecryptfs_readdir,
 435         .ioctl = ecryptfs_ioctl,
 436         .mmap = generic_file_mmap,
 437         .open = ecryptfs_open,
 438         .flush = ecryptfs_flush,
 439         .release = ecryptfs_release,
 440         .fsync = ecryptfs_fsync,
 441         .fasync = ecryptfs_fasync,
 442         .sendfile = ecryptfs_sendfile,
 443 };
 444
 445 static int
 446 ecryptfs_ioctl(struct inode *inode, struct file *file, unsigned int cmd,
 447                unsigned long arg)
 448 {
 449         int rc = 0;
 450         struct file *lower_file = NULL;
 451
 452         if (ecryptfs_file_to_private(file))
 453                 lower_file = ecryptfs_file_to_lower(file);
 454         if (lower_file && lower_file->f_op && lower_file->f_op->ioctl)
 455                 rc = lower_file->f_op->ioctl(ecryptfs_inode_to_lower(inode),
 456                                              lower_file, cmd, arg);
 457         else
 458                 rc = -ENOTTY;
 459         return rc;
 460 }