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