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 <linux/smp_lock.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         int rc;
  51         struct dentry *lower_dentry;
  52         struct vfsmount *lower_vfsmount;
  53         struct file *file = iocb->ki_filp;
  54
  55         rc = generic_file_aio_read(iocb, iov, nr_segs, pos);
  56         /*
  57          * Even though this is a async interface, we need to wait
  58          * for IO to finish to update atime
  59          */
  60         if (-EIOCBQUEUED == rc)
  61                 rc = wait_on_sync_kiocb(iocb);
  62         if (rc >= 0) {
  63                 lower_dentry = ecryptfs_dentry_to_lower(file->f_path.dentry);
  64                 lower_vfsmount = ecryptfs_dentry_to_lower_mnt(file->f_path.dentry);
  65                 touch_atime(lower_vfsmount, lower_dentry);
  66         }
  67         return rc;
  68 }
  69
  70 struct ecryptfs_getdents_callback {
  71         void *dirent;
  72         struct dentry *dentry;
  73         filldir_t filldir;
  74         int err;
  75         int filldir_called;
  76         int entries_written;
  77 };
  78
  79 /* Inspired by generic filldir in fs/readir.c */
  80 static int
  81 ecryptfs_filldir(void *dirent, const char *name, int namelen, loff_t offset,
  82                  u64 ino, unsigned int d_type)
  83 {
  84         struct ecryptfs_crypt_stat *crypt_stat;
  85         struct ecryptfs_getdents_callback *buf =
  86             (struct ecryptfs_getdents_callback *)dirent;
  87         int rc;
  88         int decoded_length;
  89         char *decoded_name;
  90
  91         crypt_stat = ecryptfs_dentry_to_private(buf->dentry)->crypt_stat;
  92         buf->filldir_called++;
  93         decoded_length = ecryptfs_decode_filename(crypt_stat, name, namelen,
  94                                                   &decoded_name);
  95         if (decoded_length < 0) {
  96                 rc = decoded_length;
  97                 goto out;
  98         }
  99         rc = buf->filldir(buf->dirent, decoded_name, decoded_length, offset,
 100                           ino, d_type);
 101         kfree(decoded_name);
 102         if (rc >= 0)
 103                 buf->entries_written++;
 104 out:
 105         return rc;
 106 }
 107
 108 /**
 109  * ecryptfs_readdir
 110  * @file: The ecryptfs file struct
 111  * @dirent: Directory entry
 112  * @filldir: The filldir callback function
 113  */
 114 static int ecryptfs_readdir(struct file *file, void *dirent, filldir_t filldir)
 115 {
 116         int rc;
 117         struct file *lower_file;
 118         struct inode *inode;
 119         struct ecryptfs_getdents_callback buf;
 120
 121         lower_file = ecryptfs_file_to_lower(file);
 122         lower_file->f_pos = file->f_pos;
 123         inode = file->f_path.dentry->d_inode;
 124         memset(&buf, 0, sizeof(buf));
 125         buf.dirent = dirent;
 126         buf.dentry = file->f_path.dentry;
 127         buf.filldir = filldir;
 128 retry:
 129         buf.filldir_called = 0;
 130         buf.entries_written = 0;
 131         buf.err = 0;
 132         rc = vfs_readdir(lower_file, ecryptfs_filldir, (void *)&buf);
 133         if (buf.err)
 134                 rc = buf.err;
 135         if (buf.filldir_called && !buf.entries_written)
 136                 goto retry;
 137         file->f_pos = lower_file->f_pos;
 138         if (rc >= 0)
 139                 fsstack_copy_attr_atime(inode, lower_file->f_path.dentry->d_inode);
 140         return rc;
 141 }
 142
 143 struct kmem_cache *ecryptfs_file_info_cache;
 144
 145 /**
 146  * ecryptfs_open
 147  * @inode: inode speciying file to open
 148  * @file: Structure to return filled in
 149  *
 150  * Opens the file specified by inode.
 151  *
 152  * Returns zero on success; non-zero otherwise
 153  */
 154 static int ecryptfs_open(struct inode *inode, struct file *file)
 155 {
 156         int rc = 0;
 157         struct ecryptfs_crypt_stat *crypt_stat = NULL;
 158         struct ecryptfs_mount_crypt_stat *mount_crypt_stat;
 159         struct dentry *ecryptfs_dentry = file->f_path.dentry;
 160         /* Private value of ecryptfs_dentry allocated in
 161          * ecryptfs_lookup() */
 162         struct dentry *lower_dentry = ecryptfs_dentry_to_lower(ecryptfs_dentry);
 163         struct ecryptfs_file_info *file_info;
 164
 165         mount_crypt_stat = &ecryptfs_superblock_to_private(
 166                 ecryptfs_dentry->d_sb)->mount_crypt_stat;
 167         if ((mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED)
 168             && ((file->f_flags & O_WRONLY) || (file->f_flags & O_RDWR)
 169                 || (file->f_flags & O_CREAT) || (file->f_flags & O_TRUNC)
 170                 || (file->f_flags & O_APPEND))) {
 171                 printk(KERN_WARNING "Mount has encrypted view enabled; "
 172                        "files may only be read\n");
 173                 rc = -EPERM;
 174                 goto out;
 175         }
 176         /* Released in ecryptfs_release or end of function if failure */
 177         file_info = kmem_cache_zalloc(ecryptfs_file_info_cache, GFP_KERNEL);
 178         ecryptfs_set_file_private(file, file_info);
 179         if (!file_info) {
 180                 ecryptfs_printk(KERN_ERR,
 181                                 "Error attempting to allocate memory\n");
 182                 rc = -ENOMEM;
 183                 goto out;
 184         }
 185         lower_dentry = ecryptfs_dentry_to_lower(ecryptfs_dentry);
 186         crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat;
 187         mutex_lock(&crypt_stat->cs_mutex);
 188         if (!(crypt_stat->flags & ECRYPTFS_POLICY_APPLIED)) {
 189                 ecryptfs_printk(KERN_DEBUG, "Setting flags for stat...\n");
 190                 /* Policy code enabled in future release */
 191                 crypt_stat->flags |= (ECRYPTFS_POLICY_APPLIED
 192                                       | ECRYPTFS_ENCRYPTED);
 193         }
 194         mutex_unlock(&crypt_stat->cs_mutex);
 195         ecryptfs_set_file_lower(
 196                 file, ecryptfs_inode_to_private(inode)->lower_file);
 197         if (S_ISDIR(ecryptfs_dentry->d_inode->i_mode)) {
 198                 ecryptfs_printk(KERN_DEBUG, "This is a directory\n");
 199                 mutex_lock(&crypt_stat->cs_mutex);
 200                 crypt_stat->flags &= ~(ECRYPTFS_ENCRYPTED);
 201                 mutex_unlock(&crypt_stat->cs_mutex);
 202                 rc = 0;
 203                 goto out;
 204         }
 205         mutex_lock(&crypt_stat->cs_mutex);
 206         if (!(crypt_stat->flags & ECRYPTFS_POLICY_APPLIED)
 207             || !(crypt_stat->flags & ECRYPTFS_KEY_VALID)) {
 208                 rc = ecryptfs_read_metadata(ecryptfs_dentry);
 209                 if (rc) {
 210                         ecryptfs_printk(KERN_DEBUG,
 211                                         "Valid headers not found\n");
 212                         if (!(mount_crypt_stat->flags
 213                               & ECRYPTFS_PLAINTEXT_PASSTHROUGH_ENABLED)) {
 214                                 rc = -EIO;
 215                                 printk(KERN_WARNING "Either the lower file "
 216                                        "is not in a valid eCryptfs format, "
 217                                        "or the key could not be retrieved. "
 218                                        "Plaintext passthrough mode is not "
 219                                        "enabled; returning -EIO\n");
 220                                 mutex_unlock(&crypt_stat->cs_mutex);
 221                                 goto out_free;
 222                         }
 223                         rc = 0;
 224                         crypt_stat->flags &= ~(ECRYPTFS_ENCRYPTED);
 225                         mutex_unlock(&crypt_stat->cs_mutex);
 226                         goto out;
 227                 }
 228         }
 229         mutex_unlock(&crypt_stat->cs_mutex);
 230         ecryptfs_printk(KERN_DEBUG, "inode w/ addr = [0x%p], i_ino = [0x%.16x] "
 231                         "size: [0x%.16x]\n", inode, inode->i_ino,
 232                         i_size_read(inode));
 233         goto out;
 234 out_free:
 235         kmem_cache_free(ecryptfs_file_info_cache,
 236                         ecryptfs_file_to_private(file));
 237 out:
 238         return rc;
 239 }
 240
 241 static int ecryptfs_flush(struct file *file, fl_owner_t td)
 242 {
 243         int rc = 0;
 244         struct file *lower_file = NULL;
 245
 246         lower_file = ecryptfs_file_to_lower(file);
 247         if (lower_file->f_op && lower_file->f_op->flush)
 248                 rc = lower_file->f_op->flush(lower_file, td);
 249         return rc;
 250 }
 251
 252 static int ecryptfs_release(struct inode *inode, struct file *file)
 253 {
 254         kmem_cache_free(ecryptfs_file_info_cache,
 255                         ecryptfs_file_to_private(file));
 256         return 0;
 257 }
 258
 259 static int
 260 ecryptfs_fsync(struct file *file, struct dentry *dentry, int datasync)
 261 {
 262         struct file *lower_file = ecryptfs_file_to_lower(file);
 263         struct dentry *lower_dentry = ecryptfs_dentry_to_lower(dentry);
 264         struct inode *lower_inode = lower_dentry->d_inode;
 265         int rc = -EINVAL;
 266
 267         if (lower_inode->i_fop->fsync) {
 268                 mutex_lock(&lower_inode->i_mutex);
 269                 rc = lower_inode->i_fop->fsync(lower_file, lower_dentry,
 270                                                datasync);
 271                 mutex_unlock(&lower_inode->i_mutex);
 272         }
 273         return rc;
 274 }
 275
 276 static int ecryptfs_fasync(int fd, struct file *file, int flag)
 277 {
 278         int rc = 0;
 279         struct file *lower_file = NULL;
 280
 281         lock_kernel();
 282         lower_file = ecryptfs_file_to_lower(file);
 283         if (lower_file->f_op && lower_file->f_op->fasync)
 284                 rc = lower_file->f_op->fasync(fd, lower_file, flag);
 285         unlock_kernel();
 286         return rc;
 287 }
 288
 289 static int ecryptfs_ioctl(struct inode *inode, struct file *file,
 290                           unsigned int cmd, unsigned long arg);
 291
 292 const struct file_operations ecryptfs_dir_fops = {
 293         .readdir = ecryptfs_readdir,
 294         .ioctl = ecryptfs_ioctl,
 295         .mmap = generic_file_mmap,
 296         .open = ecryptfs_open,
 297         .flush = ecryptfs_flush,
 298         .release = ecryptfs_release,
 299         .fsync = ecryptfs_fsync,
 300         .fasync = ecryptfs_fasync,
 301         .splice_read = generic_file_splice_read,
 302 };
 303
 304 const struct file_operations ecryptfs_main_fops = {
 305         .llseek = generic_file_llseek,
 306         .read = do_sync_read,
 307         .aio_read = ecryptfs_read_update_atime,
 308         .write = do_sync_write,
 309         .aio_write = generic_file_aio_write,
 310         .readdir = ecryptfs_readdir,
 311         .ioctl = ecryptfs_ioctl,
 312         .mmap = generic_file_mmap,
 313         .open = ecryptfs_open,
 314         .flush = ecryptfs_flush,
 315         .release = ecryptfs_release,
 316         .fsync = ecryptfs_fsync,
 317         .fasync = ecryptfs_fasync,
 318         .splice_read = generic_file_splice_read,
 319 };
 320
 321 static int
 322 ecryptfs_ioctl(struct inode *inode, struct file *file, unsigned int cmd,
 323                unsigned long arg)
 324 {
 325         int rc = 0;
 326         struct file *lower_file = NULL;
 327
 328         if (ecryptfs_file_to_private(file))
 329                 lower_file = ecryptfs_file_to_lower(file);
 330         if (lower_file && lower_file->f_op && lower_file->f_op->ioctl)
 331                 rc = lower_file->f_op->ioctl(ecryptfs_inode_to_lower(inode),
 332                                              lower_file, cmd, arg);
 333         else
 334                 rc = -ENOTTY;
 335         return rc;
 336 }