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/slab.h>
  29 #include <linux/mount.h>
  30 #include <linux/pagemap.h>
  31 #include <linux/security.h>
  32 #include <linux/compat.h>
  33 #include <linux/fs_stack.h>
  34 #include "ecryptfs_kernel.h"
  35
  36 /**
  37  * ecryptfs_read_update_atime
  38  *
  39  * generic_file_read updates the atime of upper layer inode.  But, it
  40  * doesn't give us a chance to update the atime of the lower layer
  41  * inode.  This function is a wrapper to generic_file_read.  It
  42  * updates the atime of the lower level inode if generic_file_read
  43  * returns without any errors. This is to be used only for file reads.
  44  * The function to be used for directory reads is ecryptfs_read.
  45  */
  46 static ssize_t ecryptfs_read_update_atime(struct kiocb *iocb,
  47                                 const struct iovec *iov,
  48                                 unsigned long nr_segs, loff_t pos)
  49 {
  50         ssize_t rc;
  51         struct path lower;
  52         struct file *file = iocb->ki_filp;
  53
  54         rc = generic_file_aio_read(iocb, iov, nr_segs, pos);
  55         /*
  56          * Even though this is a async interface, we need to wait
  57          * for IO to finish to update atime
  58          */
  59         if (-EIOCBQUEUED == rc)
  60                 rc = wait_on_sync_kiocb(iocb);
  61         if (rc >= 0) {
  62                 lower.dentry = ecryptfs_dentry_to_lower(file->f_path.dentry);
  63                 lower.mnt = ecryptfs_dentry_to_lower_mnt(file->f_path.dentry);
  64                 touch_atime(&lower);
  65         }
  66         return rc;
  67 }
  68
  69 struct ecryptfs_getdents_callback {
  70         void *dirent;
  71         struct dentry *dentry;
  72         filldir_t filldir;
  73         int filldir_called;
  74         int entries_written;
  75 };
  76
  77 /* Inspired by generic filldir in fs/readdir.c */
  78 static int
  79 ecryptfs_filldir(void *dirent, const char *lower_name, int lower_namelen,
  80                  loff_t offset, u64 ino, unsigned int d_type)
  81 {
  82         struct ecryptfs_getdents_callback *buf =
  83             (struct ecryptfs_getdents_callback *)dirent;
  84         size_t name_size;
  85         char *name;
  86         int rc;
  87
  88         buf->filldir_called++;
  89         rc = ecryptfs_decode_and_decrypt_filename(&name, &name_size,
  90                                                   buf->dentry, lower_name,
  91                                                   lower_namelen);
  92         if (rc) {
  93                 printk(KERN_ERR "%s: Error attempting to decode and decrypt "
  94                        "filename [%s]; rc = [%d]\n", __func__, lower_name,
  95                        rc);
  96                 goto out;
  97         }
  98         rc = buf->filldir(buf->dirent, name, name_size, offset, ino, d_type);
  99         kfree(name);
 100         if (rc >= 0)
 101                 buf->entries_written++;
 102 out:
 103         return rc;
 104 }
 105
 106 /**
 107  * ecryptfs_readdir
 108  * @file: The eCryptfs directory file
 109  * @dirent: Directory entry handle
 110  * @filldir: The filldir callback function
 111  */
 112 static int ecryptfs_readdir(struct file *file, void *dirent, filldir_t filldir)
 113 {
 114         int rc;
 115         struct file *lower_file;
 116         struct inode *inode;
 117         struct ecryptfs_getdents_callback buf;
 118
 119         lower_file = ecryptfs_file_to_lower(file);
 120         lower_file->f_pos = file->f_pos;
 121         inode = file_inode(file);
 122         memset(&buf, 0, sizeof(buf));
 123         buf.dirent = dirent;
 124         buf.dentry = file->f_path.dentry;
 125         buf.filldir = filldir;
 126         buf.filldir_called = 0;
 127         buf.entries_written = 0;
 128         rc = vfs_readdir(lower_file, ecryptfs_filldir, (void *)&buf);
 129         file->f_pos = lower_file->f_pos;
 130         if (rc < 0)
 131                 goto out;
 132         if (buf.filldir_called && !buf.entries_written)
 133                 goto out;
 134         if (rc >= 0)
 135                 fsstack_copy_attr_atime(inode,
 136                                         file_inode(lower_file));
 137 out:
 138         return rc;
 139 }
 140
 141 struct kmem_cache *ecryptfs_file_info_cache;
 142
 143 static int read_or_initialize_metadata(struct dentry *dentry)
 144 {
 145         struct inode *inode = dentry->d_inode;
 146         struct ecryptfs_mount_crypt_stat *mount_crypt_stat;
 147         struct ecryptfs_crypt_stat *crypt_stat;
 148         int rc;
 149
 150         crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat;
 151         mount_crypt_stat = &ecryptfs_superblock_to_private(
 152                                                 inode->i_sb)->mount_crypt_stat;
 153         mutex_lock(&crypt_stat->cs_mutex);
 154
 155         if (crypt_stat->flags & ECRYPTFS_POLICY_APPLIED &&
 156             crypt_stat->flags & ECRYPTFS_KEY_VALID) {
 157                 rc = 0;
 158                 goto out;
 159         }
 160
 161         rc = ecryptfs_read_metadata(dentry);
 162         if (!rc)
 163                 goto out;
 164
 165         if (mount_crypt_stat->flags & ECRYPTFS_PLAINTEXT_PASSTHROUGH_ENABLED) {
 166                 crypt_stat->flags &= ~(ECRYPTFS_I_SIZE_INITIALIZED
 167                                        | ECRYPTFS_ENCRYPTED);
 168                 rc = 0;
 169                 goto out;
 170         }
 171
 172         if (!(mount_crypt_stat->flags & ECRYPTFS_XATTR_METADATA_ENABLED) &&
 173             !i_size_read(ecryptfs_inode_to_lower(inode))) {
 174                 rc = ecryptfs_initialize_file(dentry, inode);
 175                 if (!rc)
 176                         goto out;
 177         }
 178
 179         rc = -EIO;
 180 out:
 181         mutex_unlock(&crypt_stat->cs_mutex);
 182         return rc;
 183 }
 184
 185 /**
 186  * ecryptfs_open
 187  * @inode: inode speciying file to open
 188  * @file: Structure to return filled in
 189  *
 190  * Opens the file specified by inode.
 191  *
 192  * Returns zero on success; non-zero otherwise
 193  */
 194 static int ecryptfs_open(struct inode *inode, struct file *file)
 195 {
 196         int rc = 0;
 197         struct ecryptfs_crypt_stat *crypt_stat = NULL;
 198         struct ecryptfs_mount_crypt_stat *mount_crypt_stat;
 199         struct dentry *ecryptfs_dentry = file->f_path.dentry;
 200         /* Private value of ecryptfs_dentry allocated in
 201          * ecryptfs_lookup() */
 202         struct ecryptfs_file_info *file_info;
 203
 204         mount_crypt_stat = &ecryptfs_superblock_to_private(
 205                 ecryptfs_dentry->d_sb)->mount_crypt_stat;
 206         if ((mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED)
 207             && ((file->f_flags & O_WRONLY) || (file->f_flags & O_RDWR)
 208                 || (file->f_flags & O_CREAT) || (file->f_flags & O_TRUNC)
 209                 || (file->f_flags & O_APPEND))) {
 210                 printk(KERN_WARNING "Mount has encrypted view enabled; "
 211                        "files may only be read\n");
 212                 rc = -EPERM;
 213                 goto out;
 214         }
 215         /* Released in ecryptfs_release or end of function if failure */
 216         file_info = kmem_cache_zalloc(ecryptfs_file_info_cache, GFP_KERNEL);
 217         ecryptfs_set_file_private(file, file_info);
 218         if (!file_info) {
 219                 ecryptfs_printk(KERN_ERR,
 220                                 "Error attempting to allocate memory\n");
 221                 rc = -ENOMEM;
 222                 goto out;
 223         }
 224         crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat;
 225         mutex_lock(&crypt_stat->cs_mutex);
 226         if (!(crypt_stat->flags & ECRYPTFS_POLICY_APPLIED)) {
 227                 ecryptfs_printk(KERN_DEBUG, "Setting flags for stat...\n");
 228                 /* Policy code enabled in future release */
 229                 crypt_stat->flags |= (ECRYPTFS_POLICY_APPLIED
 230                                       | ECRYPTFS_ENCRYPTED);
 231         }
 232         mutex_unlock(&crypt_stat->cs_mutex);
 233         rc = ecryptfs_get_lower_file(ecryptfs_dentry, inode);
 234         if (rc) {
 235                 printk(KERN_ERR "%s: Error attempting to initialize "
 236                         "the lower file for the dentry with name "
 237                         "[%s]; rc = [%d]\n", __func__,
 238                         ecryptfs_dentry->d_name.name, rc);
 239                 goto out_free;
 240         }
 241         if ((ecryptfs_inode_to_private(inode)->lower_file->f_flags & O_ACCMODE)
 242             == O_RDONLY && (file->f_flags & O_ACCMODE) != O_RDONLY) {
 243                 rc = -EPERM;
 244                 printk(KERN_WARNING "%s: Lower file is RO; eCryptfs "
 245                        "file must hence be opened RO\n", __func__);
 246                 goto out_put;
 247         }
 248         ecryptfs_set_file_lower(
 249                 file, ecryptfs_inode_to_private(inode)->lower_file);
 250         if (S_ISDIR(ecryptfs_dentry->d_inode->i_mode)) {
 251                 ecryptfs_printk(KERN_DEBUG, "This is a directory\n");
 252                 mutex_lock(&crypt_stat->cs_mutex);
 253                 crypt_stat->flags &= ~(ECRYPTFS_ENCRYPTED);
 254                 mutex_unlock(&crypt_stat->cs_mutex);
 255                 rc = 0;
 256                 goto out;
 257         }
 258         rc = read_or_initialize_metadata(ecryptfs_dentry);
 259         if (rc)
 260                 goto out_put;
 261         ecryptfs_printk(KERN_DEBUG, "inode w/ addr = [0x%p], i_ino = "
 262                         "[0x%.16lx] size: [0x%.16llx]\n", inode, inode->i_ino,
 263                         (unsigned long long)i_size_read(inode));
 264         goto out;
 265 out_put:
 266         ecryptfs_put_lower_file(inode);
 267 out_free:
 268         kmem_cache_free(ecryptfs_file_info_cache,
 269                         ecryptfs_file_to_private(file));
 270 out:
 271         return rc;
 272 }
 273
 274 static int ecryptfs_flush(struct file *file, fl_owner_t td)
 275 {
 276         struct file *lower_file = ecryptfs_file_to_lower(file);
 277
 278         if (lower_file->f_op && lower_file->f_op->flush) {
 279                 filemap_write_and_wait(file->f_mapping);
 280                 return lower_file->f_op->flush(lower_file, td);
 281         }
 282
 283         return 0;
 284 }
 285
 286 static int ecryptfs_release(struct inode *inode, struct file *file)
 287 {
 288         ecryptfs_put_lower_file(inode);
 289         kmem_cache_free(ecryptfs_file_info_cache,
 290                         ecryptfs_file_to_private(file));
 291         return 0;
 292 }
 293
 294 static int
 295 ecryptfs_fsync(struct file *file, loff_t start, loff_t end, int datasync)
 296 {
 297         return vfs_fsync(ecryptfs_file_to_lower(file), datasync);
 298 }
 299
 300 static int ecryptfs_fasync(int fd, struct file *file, int flag)
 301 {
 302         int rc = 0;
 303         struct file *lower_file = NULL;
 304
 305         lower_file = ecryptfs_file_to_lower(file);
 306         if (lower_file->f_op && lower_file->f_op->fasync)
 307                 rc = lower_file->f_op->fasync(fd, lower_file, flag);
 308         return rc;
 309 }
 310
 311 static long
 312 ecryptfs_unlocked_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 313 {
 314         struct file *lower_file = NULL;
 315         long rc = -ENOTTY;
 316
 317         if (ecryptfs_file_to_private(file))
 318                 lower_file = ecryptfs_file_to_lower(file);
 319         if (lower_file && lower_file->f_op && lower_file->f_op->unlocked_ioctl)
 320                 rc = lower_file->f_op->unlocked_ioctl(lower_file, cmd, arg);
 321         return rc;
 322 }
 323
 324 #ifdef CONFIG_COMPAT
 325 static long
 326 ecryptfs_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 327 {
 328         struct file *lower_file = NULL;
 329         long rc = -ENOIOCTLCMD;
 330
 331         if (ecryptfs_file_to_private(file))
 332                 lower_file = ecryptfs_file_to_lower(file);
 333         if (lower_file && lower_file->f_op && lower_file->f_op->compat_ioctl)
 334                 rc = lower_file->f_op->compat_ioctl(lower_file, cmd, arg);
 335         return rc;
 336 }
 337 #endif
 338
 339 const struct file_operations ecryptfs_dir_fops = {
 340         .readdir = ecryptfs_readdir,
 341         .read = generic_read_dir,
 342         .unlocked_ioctl = ecryptfs_unlocked_ioctl,
 343 #ifdef CONFIG_COMPAT
 344         .compat_ioctl = ecryptfs_compat_ioctl,
 345 #endif
 346         .open = ecryptfs_open,
 347         .flush = ecryptfs_flush,
 348         .release = ecryptfs_release,
 349         .fsync = ecryptfs_fsync,
 350         .fasync = ecryptfs_fasync,
 351         .splice_read = generic_file_splice_read,
 352         .llseek = default_llseek,
 353 };
 354
 355 const struct file_operations ecryptfs_main_fops = {
 356         .llseek = generic_file_llseek,
 357         .read = do_sync_read,
 358         .aio_read = ecryptfs_read_update_atime,
 359         .write = do_sync_write,
 360         .aio_write = generic_file_aio_write,
 361         .readdir = ecryptfs_readdir,
 362         .unlocked_ioctl = ecryptfs_unlocked_ioctl,
 363 #ifdef CONFIG_COMPAT
 364         .compat_ioctl = ecryptfs_compat_ioctl,
 365 #endif
 366         .mmap = generic_file_mmap,
 367         .open = ecryptfs_open,
 368         .flush = ecryptfs_flush,
 369         .release = ecryptfs_release,
 370         .fsync = ecryptfs_fsync,
 371         .fasync = ecryptfs_fasync,
 372         .splice_read = generic_file_splice_read,
 373 };