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 <linux/smp_lock.h>
  35 #include "ecryptfs_kernel.h"
  36
  37 /**
  38  * ecryptfs_read_update_atime
  39  *
  40  * generic_file_read updates the atime of upper layer inode.  But, it
  41  * doesn't give us a chance to update the atime of the lower layer
  42  * inode.  This function is a wrapper to generic_file_read.  It
  43  * updates the atime of the lower level inode if generic_file_read
  44  * returns without any errors. This is to be used only for file reads.
  45  * The function to be used for directory reads is ecryptfs_read.
  46  */
  47 static ssize_t ecryptfs_read_update_atime(struct kiocb *iocb,
  48                                 const struct iovec *iov,
  49                                 unsigned long nr_segs, loff_t pos)
  50 {
  51         int rc;
  52         struct dentry *lower_dentry;
  53         struct vfsmount *lower_vfsmount;
  54         struct file *file = iocb->ki_filp;
  55
  56         rc = generic_file_aio_read(iocb, iov, nr_segs, pos);
  57         /*
  58          * Even though this is a async interface, we need to wait
  59          * for IO to finish to update atime
  60          */
  61         if (-EIOCBQUEUED == rc)
  62                 rc = wait_on_sync_kiocb(iocb);
  63         if (rc >= 0) {
  64                 lower_dentry = ecryptfs_dentry_to_lower(file->f_path.dentry);
  65                 lower_vfsmount = ecryptfs_dentry_to_lower_mnt(file->f_path.dentry);
  66                 touch_atime(lower_vfsmount, lower_dentry);
  67         }
  68         return rc;
  69 }
  70
  71 struct ecryptfs_getdents_callback {
  72         void *dirent;
  73         struct dentry *dentry;
  74         filldir_t filldir;
  75         int filldir_called;
  76         int entries_written;
  77 };
  78
  79 /* Inspired by generic filldir in fs/readdir.c */
  80 static int
  81 ecryptfs_filldir(void *dirent, const char *lower_name, int lower_namelen,
  82                  loff_t offset, u64 ino, unsigned int d_type)
  83 {
  84         struct ecryptfs_getdents_callback *buf =
  85             (struct ecryptfs_getdents_callback *)dirent;
  86         size_t name_size;
  87         char *name;
  88         int rc;
  89
  90         buf->filldir_called++;
  91         rc = ecryptfs_decode_and_decrypt_filename(&name, &name_size,
  92                                                   buf->dentry, lower_name,
  93                                                   lower_namelen);
  94         if (rc) {
  95                 printk(KERN_ERR "%s: Error attempting to decode and decrypt "
  96                        "filename [%s]; rc = [%d]\n", __func__, lower_name,
  97                        rc);
  98                 goto out;
  99         }
 100         rc = buf->filldir(buf->dirent, name, name_size, offset, ino, d_type);
 101         kfree(name);
 102         if (rc >= 0)
 103                 buf->entries_written++;
 104 out:
 105         return rc;
 106 }
 107
 108 /**
 109  * ecryptfs_readdir
 110  * @file: The eCryptfs directory file
 111  * @dirent: Directory entry handle
 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         buf.filldir_called = 0;
 129         buf.entries_written = 0;
 130         rc = vfs_readdir(lower_file, ecryptfs_filldir, (void *)&buf);
 131         file->f_pos = lower_file->f_pos;
 132         if (rc < 0)
 133                 goto out;
 134         if (buf.filldir_called && !buf.entries_written)
 135                 goto out;
 136         if (rc >= 0)
 137                 fsstack_copy_attr_atime(inode,
 138                                         lower_file->f_path.dentry->d_inode);
 139 out:
 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;
 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         if (!ecryptfs_inode_to_private(inode)->lower_file) {
 196                 rc = ecryptfs_init_persistent_file(ecryptfs_dentry);
 197                 if (rc) {
 198                         printk(KERN_ERR "%s: Error attempting to initialize "
 199                                "the persistent file for the dentry with name "
 200                                "[%s]; rc = [%d]\n", __func__,
 201                                ecryptfs_dentry->d_name.name, rc);
 202                         goto out;
 203                 }
 204         }
 205         if ((ecryptfs_inode_to_private(inode)->lower_file->f_flags & O_RDONLY)
 206             && !(file->f_flags & O_RDONLY)) {
 207                 rc = -EPERM;
 208                 printk(KERN_WARNING "%s: Lower persistent file is RO; eCryptfs "
 209                        "file must hence be opened RO\n", __func__);
 210                 goto out;
 211         }
 212         ecryptfs_set_file_lower(
 213                 file, ecryptfs_inode_to_private(inode)->lower_file);
 214         if (S_ISDIR(ecryptfs_dentry->d_inode->i_mode)) {
 215                 ecryptfs_printk(KERN_DEBUG, "This is a directory\n");
 216                 mutex_lock(&crypt_stat->cs_mutex);
 217                 crypt_stat->flags &= ~(ECRYPTFS_ENCRYPTED);
 218                 mutex_unlock(&crypt_stat->cs_mutex);
 219                 rc = 0;
 220                 goto out;
 221         }
 222         mutex_lock(&crypt_stat->cs_mutex);
 223         if (!(crypt_stat->flags & ECRYPTFS_POLICY_APPLIED)
 224             || !(crypt_stat->flags & ECRYPTFS_KEY_VALID)) {
 225                 rc = ecryptfs_read_metadata(ecryptfs_dentry);
 226                 if (rc) {
 227                         ecryptfs_printk(KERN_DEBUG,
 228                                         "Valid headers not found\n");
 229                         if (!(mount_crypt_stat->flags
 230                               & ECRYPTFS_PLAINTEXT_PASSTHROUGH_ENABLED)) {
 231                                 rc = -EIO;
 232                                 printk(KERN_WARNING "Either the lower file "
 233                                        "is not in a valid eCryptfs format, "
 234                                        "or the key could not be retrieved. "
 235                                        "Plaintext passthrough mode is not "
 236                                        "enabled; returning -EIO\n");
 237                                 mutex_unlock(&crypt_stat->cs_mutex);
 238                                 goto out_free;
 239                         }
 240                         rc = 0;
 241                         crypt_stat->flags &= ~(ECRYPTFS_ENCRYPTED);
 242                         mutex_unlock(&crypt_stat->cs_mutex);
 243                         goto out;
 244                 }
 245         }
 246         mutex_unlock(&crypt_stat->cs_mutex);
 247         ecryptfs_printk(KERN_DEBUG, "inode w/ addr = [0x%p], i_ino = [0x%.16x] "
 248                         "size: [0x%.16x]\n", inode, inode->i_ino,
 249                         i_size_read(inode));
 250         goto out;
 251 out_free:
 252         kmem_cache_free(ecryptfs_file_info_cache,
 253                         ecryptfs_file_to_private(file));
 254 out:
 255         return rc;
 256 }
 257
 258 static int ecryptfs_flush(struct file *file, fl_owner_t td)
 259 {
 260         int rc = 0;
 261         struct file *lower_file = NULL;
 262
 263         lower_file = ecryptfs_file_to_lower(file);
 264         if (lower_file->f_op && lower_file->f_op->flush)
 265                 rc = lower_file->f_op->flush(lower_file, td);
 266         return rc;
 267 }
 268
 269 static int ecryptfs_release(struct inode *inode, struct file *file)
 270 {
 271         kmem_cache_free(ecryptfs_file_info_cache,
 272                         ecryptfs_file_to_private(file));
 273         return 0;
 274 }
 275
 276 static int
 277 ecryptfs_fsync(struct file *file, struct dentry *dentry, int datasync)
 278 {
 279         return vfs_fsync(ecryptfs_file_to_lower(file),
 280                          ecryptfs_dentry_to_lower(dentry),
 281                          datasync);
 282 }
 283
 284 static int ecryptfs_fasync(int fd, struct file *file, int flag)
 285 {
 286         int rc = 0;
 287         struct file *lower_file = NULL;
 288
 289         lock_kernel();
 290         lower_file = ecryptfs_file_to_lower(file);
 291         if (lower_file->f_op && lower_file->f_op->fasync)
 292                 rc = lower_file->f_op->fasync(fd, lower_file, flag);
 293         unlock_kernel();
 294         return rc;
 295 }
 296
 297 static int ecryptfs_ioctl(struct inode *inode, struct file *file,
 298                           unsigned int cmd, unsigned long arg);
 299
 300 const struct file_operations ecryptfs_dir_fops = {
 301         .readdir = ecryptfs_readdir,
 302         .ioctl = ecryptfs_ioctl,
 303         .open = ecryptfs_open,
 304         .flush = ecryptfs_flush,
 305         .release = ecryptfs_release,
 306         .fsync = ecryptfs_fsync,
 307         .fasync = ecryptfs_fasync,
 308         .splice_read = generic_file_splice_read,
 309 };
 310
 311 const struct file_operations ecryptfs_main_fops = {
 312         .llseek = generic_file_llseek,
 313         .read = do_sync_read,
 314         .aio_read = ecryptfs_read_update_atime,
 315         .write = do_sync_write,
 316         .aio_write = generic_file_aio_write,
 317         .readdir = ecryptfs_readdir,
 318         .ioctl = ecryptfs_ioctl,
 319         .mmap = generic_file_mmap,
 320         .open = ecryptfs_open,
 321         .flush = ecryptfs_flush,
 322         .release = ecryptfs_release,
 323         .fsync = ecryptfs_fsync,
 324         .fasync = ecryptfs_fasync,
 325         .splice_read = generic_file_splice_read,
 326 };
 327
 328 static int
 329 ecryptfs_ioctl(struct inode *inode, struct file *file, unsigned int cmd,
 330                unsigned long arg)
 331 {
 332         int rc = 0;
 333         struct file *lower_file = NULL;
 334
 335         if (ecryptfs_file_to_private(file))
 336                 lower_file = ecryptfs_file_to_lower(file);
 337         if (lower_file && lower_file->f_op && lower_file->f_op->ioctl)
 338                 rc = lower_file->f_op->ioctl(ecryptfs_inode_to_lower(inode),
 339                                              lower_file, cmd, arg);
 340         else
 341                 rc = -ENOTTY;
 342         return rc;
 343 }