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 filldir_called;
  75         int entries_written;
  76 };
  77
  78 /* Inspired by generic filldir in fs/readdir.c */
  79 static int
  80 ecryptfs_filldir(void *dirent, const char *lower_name, int lower_namelen,
  81                  loff_t offset, u64 ino, unsigned int d_type)
  82 {
  83         struct ecryptfs_getdents_callback *buf =
  84             (struct ecryptfs_getdents_callback *)dirent;
  85         size_t name_size;
  86         char *name;
  87         int rc;
  88
  89         buf->filldir_called++;
  90         rc = ecryptfs_decode_and_decrypt_filename(&name, &name_size,
  91                                                   buf->dentry, lower_name,
  92                                                   lower_namelen);
  93         if (rc) {
  94                 printk(KERN_ERR "%s: Error attempting to decode and decrypt "
  95                        "filename [%s]; rc = [%d]\n", __func__, lower_name,
  96                        rc);
  97                 goto out;
  98         }
  99         rc = buf->filldir(buf->dirent, name, name_size, offset, ino, d_type);
 100         kfree(name);
 101         if (rc >= 0)
 102                 buf->entries_written++;
 103 out:
 104         return rc;
 105 }
 106
 107 /**
 108  * ecryptfs_readdir
 109  * @file: The eCryptfs directory file
 110  * @dirent: Directory entry handle
 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         buf.filldir_called = 0;
 128         buf.entries_written = 0;
 129         rc = vfs_readdir(lower_file, ecryptfs_filldir, (void *)&buf);
 130         file->f_pos = lower_file->f_pos;
 131         if (rc < 0)
 132                 goto out;
 133         if (buf.filldir_called && !buf.entries_written)
 134                 goto out;
 135         if (rc >= 0)
 136                 fsstack_copy_attr_atime(inode,
 137                                         lower_file->f_path.dentry->d_inode);
 138 out:
 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;
 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         if (!ecryptfs_inode_to_private(inode)->lower_file) {
 195                 rc = ecryptfs_init_persistent_file(ecryptfs_dentry);
 196                 if (rc) {
 197                         printk(KERN_ERR "%s: Error attempting to initialize "
 198                                "the persistent file for the dentry with name "
 199                                "[%s]; rc = [%d]\n", __func__,
 200                                ecryptfs_dentry->d_name.name, rc);
 201                         goto out;
 202                 }
 203         }
 204         if ((ecryptfs_inode_to_private(inode)->lower_file->f_flags & O_RDONLY)
 205             && !(file->f_flags & O_RDONLY)) {
 206                 rc = -EPERM;
 207                 printk(KERN_WARNING "%s: Lower persistent file is RO; eCryptfs "
 208                        "file must hence be opened RO\n", __func__);
 209                 goto out;
 210         }
 211         ecryptfs_set_file_lower(
 212                 file, ecryptfs_inode_to_private(inode)->lower_file);
 213         if (S_ISDIR(ecryptfs_dentry->d_inode->i_mode)) {
 214                 ecryptfs_printk(KERN_DEBUG, "This is a directory\n");
 215                 mutex_lock(&crypt_stat->cs_mutex);
 216                 crypt_stat->flags &= ~(ECRYPTFS_ENCRYPTED);
 217                 mutex_unlock(&crypt_stat->cs_mutex);
 218                 rc = 0;
 219                 goto out;
 220         }
 221         mutex_lock(&crypt_stat->cs_mutex);
 222         if (!(crypt_stat->flags & ECRYPTFS_POLICY_APPLIED)
 223             || !(crypt_stat->flags & ECRYPTFS_KEY_VALID)) {
 224                 rc = ecryptfs_read_metadata(ecryptfs_dentry);
 225                 if (rc) {
 226                         ecryptfs_printk(KERN_DEBUG,
 227                                         "Valid headers not found\n");
 228                         if (!(mount_crypt_stat->flags
 229                               & ECRYPTFS_PLAINTEXT_PASSTHROUGH_ENABLED)) {
 230                                 rc = -EIO;
 231                                 printk(KERN_WARNING "Either the lower file "
 232                                        "is not in a valid eCryptfs format, "
 233                                        "or the key could not be retrieved. "
 234                                        "Plaintext passthrough mode is not "
 235                                        "enabled; returning -EIO\n");
 236                                 mutex_unlock(&crypt_stat->cs_mutex);
 237                                 goto out_free;
 238                         }
 239                         rc = 0;
 240                         crypt_stat->flags &= ~(ECRYPTFS_ENCRYPTED);
 241                         mutex_unlock(&crypt_stat->cs_mutex);
 242                         goto out;
 243                 }
 244         }
 245         mutex_unlock(&crypt_stat->cs_mutex);
 246         ecryptfs_printk(KERN_DEBUG, "inode w/ addr = [0x%p], i_ino = [0x%.16x] "
 247                         "size: [0x%.16x]\n", inode, inode->i_ino,
 248                         i_size_read(inode));
 249         goto out;
 250 out_free:
 251         kmem_cache_free(ecryptfs_file_info_cache,
 252                         ecryptfs_file_to_private(file));
 253 out:
 254         return rc;
 255 }
 256
 257 static int ecryptfs_flush(struct file *file, fl_owner_t td)
 258 {
 259         int rc = 0;
 260         struct file *lower_file = NULL;
 261
 262         lower_file = ecryptfs_file_to_lower(file);
 263         if (lower_file->f_op && lower_file->f_op->flush)
 264                 rc = lower_file->f_op->flush(lower_file, td);
 265         return rc;
 266 }
 267
 268 static int ecryptfs_release(struct inode *inode, struct file *file)
 269 {
 270         kmem_cache_free(ecryptfs_file_info_cache,
 271                         ecryptfs_file_to_private(file));
 272         return 0;
 273 }
 274
 275 static int
 276 ecryptfs_fsync(struct file *file, struct dentry *dentry, int datasync)
 277 {
 278         return vfs_fsync(ecryptfs_file_to_lower(file),
 279                          ecryptfs_dentry_to_lower(dentry),
 280                          datasync);
 281 }
 282
 283 static int ecryptfs_fasync(int fd, struct file *file, int flag)
 284 {
 285         int rc = 0;
 286         struct file *lower_file = NULL;
 287
 288         lock_kernel();
 289         lower_file = ecryptfs_file_to_lower(file);
 290         if (lower_file->f_op && lower_file->f_op->fasync)
 291                 rc = lower_file->f_op->fasync(fd, lower_file, flag);
 292         unlock_kernel();
 293         return rc;
 294 }
 295
 296 static int ecryptfs_ioctl(struct inode *inode, struct file *file,
 297                           unsigned int cmd, unsigned long arg);
 298
 299 const struct file_operations ecryptfs_dir_fops = {
 300         .readdir = ecryptfs_readdir,
 301         .ioctl = ecryptfs_ioctl,
 302         .open = ecryptfs_open,
 303         .flush = ecryptfs_flush,
 304         .release = ecryptfs_release,
 305         .fsync = ecryptfs_fsync,
 306         .fasync = ecryptfs_fasync,
 307         .splice_read = generic_file_splice_read,
 308 };
 309
 310 const struct file_operations ecryptfs_main_fops = {
 311         .llseek = generic_file_llseek,
 312         .read = do_sync_read,
 313         .aio_read = ecryptfs_read_update_atime,
 314         .write = do_sync_write,
 315         .aio_write = generic_file_aio_write,
 316         .readdir = ecryptfs_readdir,
 317         .ioctl = ecryptfs_ioctl,
 318         .mmap = generic_file_mmap,
 319         .open = ecryptfs_open,
 320         .flush = ecryptfs_flush,
 321         .release = ecryptfs_release,
 322         .fsync = ecryptfs_fsync,
 323         .fasync = ecryptfs_fasync,
 324         .splice_read = generic_file_splice_read,
 325 };
 326
 327 static int
 328 ecryptfs_ioctl(struct inode *inode, struct file *file, unsigned int cmd,
 329                unsigned long arg)
 330 {
 331         int rc = 0;
 332         struct file *lower_file = NULL;
 333
 334         if (ecryptfs_file_to_private(file))
 335                 lower_file = ecryptfs_file_to_lower(file);
 336         if (lower_file && lower_file->f_op && lower_file->f_op->ioctl)
 337                 rc = lower_file->f_op->ioctl(ecryptfs_inode_to_lower(inode),
 338                                              lower_file, cmd, arg);
 339         else
 340                 rc = -ENOTTY;
 341         return rc;
 342 }