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/compat.h>
  32 #include <linux/fs_stack.h>
  33 #include "ecryptfs_kernel.h"
  34
  35 /**
  36  * ecryptfs_read_update_atime
  37  *
  38  * generic_file_read updates the atime of upper layer inode.  But, it
  39  * doesn't give us a chance to update the atime of the lower layer
  40  * inode.  This function is a wrapper to generic_file_read.  It
  41  * updates the atime of the lower level inode if generic_file_read
  42  * returns without any errors. This is to be used only for file reads.
  43  * The function to be used for directory reads is ecryptfs_read.
  44  */
  45 static ssize_t ecryptfs_read_update_atime(struct kiocb *iocb,
  46                                 const struct iovec *iov,
  47                                 unsigned long nr_segs, loff_t pos)
  48 {
  49         int rc;
  50         struct dentry *lower_dentry;
  51         struct vfsmount *lower_vfsmount;
  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_vfsmount = ecryptfs_dentry_to_lower_mnt(file->f_path.dentry);
  64                 touch_atime(lower_vfsmount, lower_dentry);
  65         }
  66         return rc;
  67 }
  68
  69 struct ecryptfs_getdents_callback {
  70         void *dirent;
  71         struct dentry *dentry;
  72         filldir_t filldir;
  73         int err;
  74         int filldir_called;
  75         int entries_written;
  76 };
  77
  78 /* Inspired by generic filldir in fs/readir.c */
  79 static int
  80 ecryptfs_filldir(void *dirent, const char *name, int namelen, loff_t offset,
  81                  u64 ino, unsigned int d_type)
  82 {
  83         struct ecryptfs_crypt_stat *crypt_stat;
  84         struct ecryptfs_getdents_callback *buf =
  85             (struct ecryptfs_getdents_callback *)dirent;
  86         int rc;
  87         int decoded_length;
  88         char *decoded_name;
  89
  90         crypt_stat = ecryptfs_dentry_to_private(buf->dentry)->crypt_stat;
  91         buf->filldir_called++;
  92         decoded_length = ecryptfs_decode_filename(crypt_stat, name, namelen,
  93                                                   &decoded_name);
  94         if (decoded_length < 0) {
  95                 rc = decoded_length;
  96                 goto out;
  97         }
  98         rc = buf->filldir(buf->dirent, decoded_name, decoded_length, offset,
  99                           ino, d_type);
 100         kfree(decoded_name);
 101         if (rc >= 0)
 102                 buf->entries_written++;
 103 out:
 104         return rc;
 105 }
 106
 107 /**
 108  * ecryptfs_readdir
 109  * @file: The ecryptfs file struct
 110  * @dirent: Directory entry
 111  * @filldir: The filldir callback function
 112  */
 113 static int ecryptfs_readdir(struct file *file, void *dirent, filldir_t filldir)
 114 {
 115         int rc;
 116         struct file *lower_file;
 117         struct inode *inode;
 118         struct ecryptfs_getdents_callback buf;
 119
 120         lower_file = ecryptfs_file_to_lower(file);
 121         lower_file->f_pos = file->f_pos;
 122         inode = file->f_path.dentry->d_inode;
 123         memset(&buf, 0, sizeof(buf));
 124         buf.dirent = dirent;
 125         buf.dentry = file->f_path.dentry;
 126         buf.filldir = filldir;
 127 retry:
 128         buf.filldir_called = 0;
 129         buf.entries_written = 0;
 130         buf.err = 0;
 131         rc = vfs_readdir(lower_file, ecryptfs_filldir, (void *)&buf);
 132         if (buf.err)
 133                 rc = buf.err;
 134         if (buf.filldir_called && !buf.entries_written)
 135                 goto retry;
 136         file->f_pos = lower_file->f_pos;
 137         if (rc >= 0)
 138                 fsstack_copy_attr_atime(inode, lower_file->f_path.dentry->d_inode);
 139         return rc;
 140 }
 141
 142 struct kmem_cache *ecryptfs_file_info_cache;
 143
 144 /**
 145  * ecryptfs_open
 146  * @inode: inode speciying file to open
 147  * @file: Structure to return filled in
 148  *
 149  * Opens the file specified by inode.
 150  *
 151  * Returns zero on success; non-zero otherwise
 152  */
 153 static int ecryptfs_open(struct inode *inode, struct file *file)
 154 {
 155         int rc = 0;
 156         struct ecryptfs_crypt_stat *crypt_stat = NULL;
 157         struct ecryptfs_mount_crypt_stat *mount_crypt_stat;
 158         struct dentry *ecryptfs_dentry = file->f_path.dentry;
 159         /* Private value of ecryptfs_dentry allocated in
 160          * ecryptfs_lookup() */
 161         struct dentry *lower_dentry = ecryptfs_dentry_to_lower(ecryptfs_dentry);
 162         struct ecryptfs_file_info *file_info;
 163
 164         mount_crypt_stat = &ecryptfs_superblock_to_private(
 165                 ecryptfs_dentry->d_sb)->mount_crypt_stat;
 166         if ((mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED)
 167             && ((file->f_flags & O_WRONLY) || (file->f_flags & O_RDWR)
 168                 || (file->f_flags & O_CREAT) || (file->f_flags & O_TRUNC)
 169                 || (file->f_flags & O_APPEND))) {
 170                 printk(KERN_WARNING "Mount has encrypted view enabled; "
 171                        "files may only be read\n");
 172                 rc = -EPERM;
 173                 goto out;
 174         }
 175         /* Released in ecryptfs_release or end of function if failure */
 176         file_info = kmem_cache_zalloc(ecryptfs_file_info_cache, GFP_KERNEL);
 177         ecryptfs_set_file_private(file, file_info);
 178         if (!file_info) {
 179                 ecryptfs_printk(KERN_ERR,
 180                                 "Error attempting to allocate memory\n");
 181                 rc = -ENOMEM;
 182                 goto out;
 183         }
 184         lower_dentry = ecryptfs_dentry_to_lower(ecryptfs_dentry);
 185         crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat;
 186         mutex_lock(&crypt_stat->cs_mutex);
 187         if (!(crypt_stat->flags & ECRYPTFS_POLICY_APPLIED)) {
 188                 ecryptfs_printk(KERN_DEBUG, "Setting flags for stat...\n");
 189                 /* Policy code enabled in future release */
 190                 crypt_stat->flags |= (ECRYPTFS_POLICY_APPLIED
 191                                       | ECRYPTFS_ENCRYPTED);
 192         }
 193         mutex_unlock(&crypt_stat->cs_mutex);
 194         ecryptfs_set_file_lower(
 195                 file, ecryptfs_inode_to_private(inode)->lower_file);
 196         if (S_ISDIR(ecryptfs_dentry->d_inode->i_mode)) {
 197                 ecryptfs_printk(KERN_DEBUG, "This is a directory\n");
 198                 mutex_lock(&crypt_stat->cs_mutex);
 199                 crypt_stat->flags &= ~(ECRYPTFS_ENCRYPTED);
 200                 mutex_unlock(&crypt_stat->cs_mutex);
 201                 rc = 0;
 202                 goto out;
 203         }
 204         mutex_lock(&crypt_stat->cs_mutex);
 205         if (!(crypt_stat->flags & ECRYPTFS_POLICY_APPLIED)
 206             || !(crypt_stat->flags & ECRYPTFS_KEY_VALID)) {
 207                 rc = ecryptfs_read_metadata(ecryptfs_dentry);
 208                 if (rc) {
 209                         ecryptfs_printk(KERN_DEBUG,
 210                                         "Valid headers not found\n");
 211                         if (!(mount_crypt_stat->flags
 212                               & ECRYPTFS_PLAINTEXT_PASSTHROUGH_ENABLED)) {
 213                                 rc = -EIO;
 214                                 printk(KERN_WARNING "Either the lower file "
 215                                        "is not in a valid eCryptfs format, "
 216                                        "or the key could not be retrieved. "
 217                                        "Plaintext passthrough mode is not "
 218                                        "enabled; returning -EIO\n");
 219                                 mutex_unlock(&crypt_stat->cs_mutex);
 220                                 goto out_free;
 221                         }
 222                         rc = 0;
 223                         crypt_stat->flags &= ~(ECRYPTFS_ENCRYPTED);
 224                         mutex_unlock(&crypt_stat->cs_mutex);
 225                         goto out;
 226                 }
 227         }
 228         mutex_unlock(&crypt_stat->cs_mutex);
 229         ecryptfs_printk(KERN_DEBUG, "inode w/ addr = [0x%p], i_ino = [0x%.16x] "
 230                         "size: [0x%.16x]\n", inode, inode->i_ino,
 231                         i_size_read(inode));
 232         goto out;
 233 out_free:
 234         kmem_cache_free(ecryptfs_file_info_cache,
 235                         ecryptfs_file_to_private(file));
 236 out:
 237         return rc;
 238 }
 239
 240 static int ecryptfs_flush(struct file *file, fl_owner_t td)
 241 {
 242         int rc = 0;
 243         struct file *lower_file = NULL;
 244
 245         lower_file = ecryptfs_file_to_lower(file);
 246         if (lower_file->f_op && lower_file->f_op->flush)
 247                 rc = lower_file->f_op->flush(lower_file, td);
 248         return rc;
 249 }
 250
 251 static int ecryptfs_release(struct inode *inode, struct file *file)
 252 {
 253         kmem_cache_free(ecryptfs_file_info_cache,
 254                         ecryptfs_file_to_private(file));
 255         return 0;
 256 }
 257
 258 static int
 259 ecryptfs_fsync(struct file *file, struct dentry *dentry, int datasync)
 260 {
 261         struct file *lower_file = ecryptfs_file_to_lower(file);
 262         struct dentry *lower_dentry = ecryptfs_dentry_to_lower(dentry);
 263         struct inode *lower_inode = lower_dentry->d_inode;
 264         int rc = -EINVAL;
 265
 266         if (lower_inode->i_fop->fsync) {
 267                 mutex_lock(&lower_inode->i_mutex);
 268                 rc = lower_inode->i_fop->fsync(lower_file, lower_dentry,
 269                                                datasync);
 270                 mutex_unlock(&lower_inode->i_mutex);
 271         }
 272         return rc;
 273 }
 274
 275 static int ecryptfs_fasync(int fd, struct file *file, int flag)
 276 {
 277         int rc = 0;
 278         struct file *lower_file = NULL;
 279
 280         lower_file = ecryptfs_file_to_lower(file);
 281         if (lower_file->f_op && lower_file->f_op->fasync)
 282                 rc = lower_file->f_op->fasync(fd, lower_file, flag);
 283         return rc;
 284 }
 285
 286 static int ecryptfs_ioctl(struct inode *inode, struct file *file,
 287                           unsigned int cmd, unsigned long arg);
 288
 289 const struct file_operations ecryptfs_dir_fops = {
 290         .readdir = ecryptfs_readdir,
 291         .ioctl = ecryptfs_ioctl,
 292         .mmap = generic_file_mmap,
 293         .open = ecryptfs_open,
 294         .flush = ecryptfs_flush,
 295         .release = ecryptfs_release,
 296         .fsync = ecryptfs_fsync,
 297         .fasync = ecryptfs_fasync,
 298         .splice_read = generic_file_splice_read,
 299 };
 300
 301 const struct file_operations ecryptfs_main_fops = {
 302         .llseek = generic_file_llseek,
 303         .read = do_sync_read,
 304         .aio_read = ecryptfs_read_update_atime,
 305         .write = do_sync_write,
 306         .aio_write = generic_file_aio_write,
 307         .readdir = ecryptfs_readdir,
 308         .ioctl = ecryptfs_ioctl,
 309         .mmap = generic_file_mmap,
 310         .open = ecryptfs_open,
 311         .flush = ecryptfs_flush,
 312         .release = ecryptfs_release,
 313         .fsync = ecryptfs_fsync,
 314         .fasync = ecryptfs_fasync,
 315         .splice_read = generic_file_splice_read,
 316 };
 317
 318 static int
 319 ecryptfs_ioctl(struct inode *inode, struct file *file, unsigned int cmd,
 320                unsigned long arg)
 321 {
 322         int rc = 0;
 323         struct file *lower_file = NULL;
 324
 325         if (ecryptfs_file_to_private(file))
 326                 lower_file = ecryptfs_file_to_lower(file);
 327         if (lower_file && lower_file->f_op && lower_file->f_op->ioctl)
 328                 rc = lower_file->f_op->ioctl(ecryptfs_inode_to_lower(inode),
 329                                              lower_file, cmd, arg);
 330         else
 331                 rc = -ENOTTY;
 332         return rc;
 333 }