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 int ecryptfs_open_lower_file(struct file **lower_file,
 145                              struct dentry *lower_dentry,
 146                              struct vfsmount *lower_mnt, int flags)
 147 {
 148         int rc = 0;
 149
 150         flags |= O_LARGEFILE;
 151         dget(lower_dentry);
 152         mntget(lower_mnt);
 153         *lower_file = dentry_open(lower_dentry, lower_mnt, flags);
 154         if (IS_ERR(*lower_file)) {
 155                 printk(KERN_ERR "Error opening lower file for lower_dentry "
 156                        "[0x%p], lower_mnt [0x%p], and flags [0x%x]\n",
 157                        lower_dentry, lower_mnt, flags);
 158                 rc = PTR_ERR(*lower_file);
 159                 *lower_file = NULL;
 160                 goto out;
 161         }
 162 out:
 163         return rc;
 164 }
 165
 166 int ecryptfs_close_lower_file(struct file *lower_file)
 167 {
 168         fput(lower_file);
 169         return 0;
 170 }
 171
 172 /**
 173  * ecryptfs_open
 174  * @inode: inode speciying file to open
 175  * @file: Structure to return filled in
 176  *
 177  * Opens the file specified by inode.
 178  *
 179  * Returns zero on success; non-zero otherwise
 180  */
 181 static int ecryptfs_open(struct inode *inode, struct file *file)
 182 {
 183         int rc = 0;
 184         struct ecryptfs_crypt_stat *crypt_stat = NULL;
 185         struct ecryptfs_mount_crypt_stat *mount_crypt_stat;
 186         struct dentry *ecryptfs_dentry = file->f_path.dentry;
 187         /* Private value of ecryptfs_dentry allocated in
 188          * ecryptfs_lookup() */
 189         struct dentry *lower_dentry = ecryptfs_dentry_to_lower(ecryptfs_dentry);
 190         struct ecryptfs_file_info *file_info;
 191
 192         mount_crypt_stat = &ecryptfs_superblock_to_private(
 193                 ecryptfs_dentry->d_sb)->mount_crypt_stat;
 194         if ((mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED)
 195             && ((file->f_flags & O_WRONLY) || (file->f_flags & O_RDWR)
 196                 || (file->f_flags & O_CREAT) || (file->f_flags & O_TRUNC)
 197                 || (file->f_flags & O_APPEND))) {
 198                 printk(KERN_WARNING "Mount has encrypted view enabled; "
 199                        "files may only be read\n");
 200                 rc = -EPERM;
 201                 goto out;
 202         }
 203         /* Released in ecryptfs_release or end of function if failure */
 204         file_info = kmem_cache_zalloc(ecryptfs_file_info_cache, GFP_KERNEL);
 205         ecryptfs_set_file_private(file, file_info);
 206         if (!file_info) {
 207                 ecryptfs_printk(KERN_ERR,
 208                                 "Error attempting to allocate memory\n");
 209                 rc = -ENOMEM;
 210                 goto out;
 211         }
 212         lower_dentry = ecryptfs_dentry_to_lower(ecryptfs_dentry);
 213         crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat;
 214         mutex_lock(&crypt_stat->cs_mutex);
 215         if (!(crypt_stat->flags & ECRYPTFS_POLICY_APPLIED)) {
 216                 ecryptfs_printk(KERN_DEBUG, "Setting flags for stat...\n");
 217                 /* Policy code enabled in future release */
 218                 crypt_stat->flags |= (ECRYPTFS_POLICY_APPLIED
 219                                       | ECRYPTFS_ENCRYPTED);
 220         }
 221         mutex_unlock(&crypt_stat->cs_mutex);
 222         ecryptfs_set_file_lower(
 223                 file, ecryptfs_inode_to_private(inode)->lower_file);
 224         if (S_ISDIR(ecryptfs_dentry->d_inode->i_mode)) {
 225                 ecryptfs_printk(KERN_DEBUG, "This is a directory\n");
 226                 crypt_stat->flags &= ~(ECRYPTFS_ENCRYPTED);
 227                 rc = 0;
 228                 goto out;
 229         }
 230         mutex_lock(&crypt_stat->cs_mutex);
 231         if (!(crypt_stat->flags & ECRYPTFS_POLICY_APPLIED)
 232             || !(crypt_stat->flags & ECRYPTFS_KEY_VALID)) {
 233                 rc = ecryptfs_read_metadata(ecryptfs_dentry);
 234                 if (rc) {
 235                         ecryptfs_printk(KERN_DEBUG,
 236                                         "Valid headers not found\n");
 237                         if (!(mount_crypt_stat->flags
 238                               & ECRYPTFS_PLAINTEXT_PASSTHROUGH_ENABLED)) {
 239                                 rc = -EIO;
 240                                 printk(KERN_WARNING "Attempt to read file that "
 241                                        "is not in a valid eCryptfs format, "
 242                                        "and plaintext passthrough mode is not "
 243                                        "enabled; returning -EIO\n");
 244                                 mutex_unlock(&crypt_stat->cs_mutex);
 245                                 goto out_free;
 246                         }
 247                         rc = 0;
 248                         crypt_stat->flags &= ~(ECRYPTFS_ENCRYPTED);
 249                         mutex_unlock(&crypt_stat->cs_mutex);
 250                         goto out;
 251                 }
 252         }
 253         mutex_unlock(&crypt_stat->cs_mutex);
 254         ecryptfs_printk(KERN_DEBUG, "inode w/ addr = [0x%p], i_ino = [0x%.16x] "
 255                         "size: [0x%.16x]\n", inode, inode->i_ino,
 256                         i_size_read(inode));
 257         goto out;
 258 out_free:
 259         kmem_cache_free(ecryptfs_file_info_cache,
 260                         ecryptfs_file_to_private(file));
 261 out:
 262         return rc;
 263 }
 264
 265 static int ecryptfs_flush(struct file *file, fl_owner_t td)
 266 {
 267         int rc = 0;
 268         struct file *lower_file = NULL;
 269
 270         lower_file = ecryptfs_file_to_lower(file);
 271         if (lower_file->f_op && lower_file->f_op->flush)
 272                 rc = lower_file->f_op->flush(lower_file, td);
 273         return rc;
 274 }
 275
 276 static int ecryptfs_release(struct inode *inode, struct file *file)
 277 {
 278         kmem_cache_free(ecryptfs_file_info_cache,
 279                         ecryptfs_file_to_private(file));
 280         return 0;
 281 }
 282
 283 static int
 284 ecryptfs_fsync(struct file *file, struct dentry *dentry, int datasync)
 285 {
 286         struct file *lower_file = ecryptfs_file_to_lower(file);
 287         struct dentry *lower_dentry = ecryptfs_dentry_to_lower(dentry);
 288         struct inode *lower_inode = lower_dentry->d_inode;
 289         int rc = -EINVAL;
 290
 291         if (lower_inode->i_fop->fsync) {
 292                 mutex_lock(&lower_inode->i_mutex);
 293                 rc = lower_inode->i_fop->fsync(lower_file, lower_dentry,
 294                                                datasync);
 295                 mutex_unlock(&lower_inode->i_mutex);
 296         }
 297         return rc;
 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 int ecryptfs_ioctl(struct inode *inode, struct file *file,
 312                           unsigned int cmd, unsigned long arg);
 313
 314 const struct file_operations ecryptfs_dir_fops = {
 315         .readdir = ecryptfs_readdir,
 316         .ioctl = ecryptfs_ioctl,
 317         .mmap = generic_file_mmap,
 318         .open = ecryptfs_open,
 319         .flush = ecryptfs_flush,
 320         .release = ecryptfs_release,
 321         .fsync = ecryptfs_fsync,
 322         .fasync = ecryptfs_fasync,
 323         .splice_read = generic_file_splice_read,
 324 };
 325
 326 const struct file_operations ecryptfs_main_fops = {
 327         .llseek = generic_file_llseek,
 328         .read = do_sync_read,
 329         .aio_read = ecryptfs_read_update_atime,
 330         .write = do_sync_write,
 331         .aio_write = generic_file_aio_write,
 332         .readdir = ecryptfs_readdir,
 333         .ioctl = ecryptfs_ioctl,
 334         .mmap = generic_file_mmap,
 335         .open = ecryptfs_open,
 336         .flush = ecryptfs_flush,
 337         .release = ecryptfs_release,
 338         .fsync = ecryptfs_fsync,
 339         .fasync = ecryptfs_fasync,
 340         .splice_read = generic_file_splice_read,
 341 };
 342
 343 static int
 344 ecryptfs_ioctl(struct inode *inode, struct file *file, unsigned int cmd,
 345                unsigned long arg)
 346 {
 347         int rc = 0;
 348         struct file *lower_file = NULL;
 349
 350         if (ecryptfs_file_to_private(file))
 351                 lower_file = ecryptfs_file_to_lower(file);
 352         if (lower_file && lower_file->f_op && lower_file->f_op->ioctl)
 353                 rc = lower_file->f_op->ioctl(ecryptfs_inode_to_lower(inode),
 354                                              lower_file, cmd, arg);
 355         else
 356                 rc = -ENOTTY;
 357         return rc;
 358 }