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/aio.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         ssize_t rc;
  52         struct path lower;
  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.mnt = ecryptfs_dentry_to_lower_mnt(file->f_path.dentry);
  65                 touch_atime(&lower);
  66         }
  67         return rc;
  68 }
  69
  70 struct ecryptfs_getdents_callback {
  71         struct dir_context ctx;
  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_inode(file);
 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         buf.ctx.actor = ecryptfs_filldir;
 131         rc = iterate_dir(lower_file, &buf.ctx);
 132         file->f_pos = lower_file->f_pos;
 133         if (rc < 0)
 134                 goto out;
 135         if (buf.filldir_called && !buf.entries_written)
 136                 goto out;
 137         if (rc >= 0)
 138                 fsstack_copy_attr_atime(inode,
 139                                         file_inode(lower_file));
 140 out:
 141         return rc;
 142 }
 143
 144 struct kmem_cache *ecryptfs_file_info_cache;
 145
 146 static int read_or_initialize_metadata(struct dentry *dentry)
 147 {
 148         struct inode *inode = dentry->d_inode;
 149         struct ecryptfs_mount_crypt_stat *mount_crypt_stat;
 150         struct ecryptfs_crypt_stat *crypt_stat;
 151         int rc;
 152
 153         crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat;
 154         mount_crypt_stat = &ecryptfs_superblock_to_private(
 155                                                 inode->i_sb)->mount_crypt_stat;
 156         mutex_lock(&crypt_stat->cs_mutex);
 157
 158         if (crypt_stat->flags & ECRYPTFS_POLICY_APPLIED &&
 159             crypt_stat->flags & ECRYPTFS_KEY_VALID) {
 160                 rc = 0;
 161                 goto out;
 162         }
 163
 164         rc = ecryptfs_read_metadata(dentry);
 165         if (!rc)
 166                 goto out;
 167
 168         if (mount_crypt_stat->flags & ECRYPTFS_PLAINTEXT_PASSTHROUGH_ENABLED) {
 169                 crypt_stat->flags &= ~(ECRYPTFS_I_SIZE_INITIALIZED
 170                                        | ECRYPTFS_ENCRYPTED);
 171                 rc = 0;
 172                 goto out;
 173         }
 174
 175         if (!(mount_crypt_stat->flags & ECRYPTFS_XATTR_METADATA_ENABLED) &&
 176             !i_size_read(ecryptfs_inode_to_lower(inode))) {
 177                 rc = ecryptfs_initialize_file(dentry, inode);
 178                 if (!rc)
 179                         goto out;
 180         }
 181
 182         rc = -EIO;
 183 out:
 184         mutex_unlock(&crypt_stat->cs_mutex);
 185         return rc;
 186 }
 187
 188 static int ecryptfs_mmap(struct file *file, struct vm_area_struct *vma)
 189 {
 190         struct file *lower_file = ecryptfs_file_to_lower(file);
 191         /*
 192          * Don't allow mmap on top of file systems that don't support it
 193          * natively.  If FILESYSTEM_MAX_STACK_DEPTH > 2 or ecryptfs
 194          * allows recursive mounting, this will need to be extended.
 195          */
 196         if (!lower_file->f_op->mmap)
 197                 return -ENODEV;
 198         return generic_file_mmap(file, vma);
 199 }
 200
 201 /**
 202  * ecryptfs_open
 203  * @inode: inode speciying file to open
 204  * @file: Structure to return filled in
 205  *
 206  * Opens the file specified by inode.
 207  *
 208  * Returns zero on success; non-zero otherwise
 209  */
 210 static int ecryptfs_open(struct inode *inode, struct file *file)
 211 {
 212         int rc = 0;
 213         struct ecryptfs_crypt_stat *crypt_stat = NULL;
 214         struct dentry *ecryptfs_dentry = file->f_path.dentry;
 215         /* Private value of ecryptfs_dentry allocated in
 216          * ecryptfs_lookup() */
 217         struct ecryptfs_file_info *file_info;
 218
 219         /* Released in ecryptfs_release or end of function if failure */
 220         file_info = kmem_cache_zalloc(ecryptfs_file_info_cache, GFP_KERNEL);
 221         ecryptfs_set_file_private(file, file_info);
 222         if (!file_info) {
 223                 ecryptfs_printk(KERN_ERR,
 224                                 "Error attempting to allocate memory\n");
 225                 rc = -ENOMEM;
 226                 goto out;
 227         }
 228         crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat;
 229         mutex_lock(&crypt_stat->cs_mutex);
 230         if (!(crypt_stat->flags & ECRYPTFS_POLICY_APPLIED)) {
 231                 ecryptfs_printk(KERN_DEBUG, "Setting flags for stat...\n");
 232                 /* Policy code enabled in future release */
 233                 crypt_stat->flags |= (ECRYPTFS_POLICY_APPLIED
 234                                       | ECRYPTFS_ENCRYPTED);
 235         }
 236         mutex_unlock(&crypt_stat->cs_mutex);
 237         rc = ecryptfs_get_lower_file(ecryptfs_dentry, inode);
 238         if (rc) {
 239                 printk(KERN_ERR "%s: Error attempting to initialize "
 240                         "the lower file for the dentry with name "
 241                         "[%s]; rc = [%d]\n", __func__,
 242                         ecryptfs_dentry->d_name.name, rc);
 243                 goto out_free;
 244         }
 245         if ((ecryptfs_inode_to_private(inode)->lower_file->f_flags & O_ACCMODE)
 246             == O_RDONLY && (file->f_flags & O_ACCMODE) != O_RDONLY) {
 247                 rc = -EPERM;
 248                 printk(KERN_WARNING "%s: Lower file is RO; eCryptfs "
 249                        "file must hence be opened RO\n", __func__);
 250                 goto out_put;
 251         }
 252         ecryptfs_set_file_lower(
 253                 file, ecryptfs_inode_to_private(inode)->lower_file);
 254         if (S_ISDIR(ecryptfs_dentry->d_inode->i_mode)) {
 255                 ecryptfs_printk(KERN_DEBUG, "This is a directory\n");
 256                 mutex_lock(&crypt_stat->cs_mutex);
 257                 crypt_stat->flags &= ~(ECRYPTFS_ENCRYPTED);
 258                 mutex_unlock(&crypt_stat->cs_mutex);
 259                 rc = 0;
 260                 goto out;
 261         }
 262         rc = read_or_initialize_metadata(ecryptfs_dentry);
 263         if (rc)
 264                 goto out_put;
 265         ecryptfs_printk(KERN_DEBUG, "inode w/ addr = [0x%p], i_ino = "
 266                         "[0x%.16lx] size: [0x%.16llx]\n", inode, inode->i_ino,
 267                         (unsigned long long)i_size_read(inode));
 268         goto out;
 269 out_put:
 270         ecryptfs_put_lower_file(inode);
 271 out_free:
 272         kmem_cache_free(ecryptfs_file_info_cache,
 273                         ecryptfs_file_to_private(file));
 274 out:
 275         return rc;
 276 }
 277
 278 static int ecryptfs_flush(struct file *file, fl_owner_t td)
 279 {
 280         struct file *lower_file = ecryptfs_file_to_lower(file);
 281
 282         if (lower_file->f_op && lower_file->f_op->flush) {
 283                 filemap_write_and_wait(file->f_mapping);
 284                 return lower_file->f_op->flush(lower_file, td);
 285         }
 286
 287         return 0;
 288 }
 289
 290 static int ecryptfs_release(struct inode *inode, struct file *file)
 291 {
 292         ecryptfs_put_lower_file(inode);
 293         kmem_cache_free(ecryptfs_file_info_cache,
 294                         ecryptfs_file_to_private(file));
 295         return 0;
 296 }
 297
 298 static int
 299 ecryptfs_fsync(struct file *file, loff_t start, loff_t end, int datasync)
 300 {
 301         int rc;
 302
 303         rc = filemap_write_and_wait(file->f_mapping);
 304         if (rc)
 305                 return rc;
 306
 307         return vfs_fsync(ecryptfs_file_to_lower(file), datasync);
 308 }
 309
 310 static int ecryptfs_fasync(int fd, struct file *file, int flag)
 311 {
 312         int rc = 0;
 313         struct file *lower_file = NULL;
 314
 315         lower_file = ecryptfs_file_to_lower(file);
 316         if (lower_file->f_op && lower_file->f_op->fasync)
 317                 rc = lower_file->f_op->fasync(fd, lower_file, flag);
 318         return rc;
 319 }
 320
 321 static long
 322 ecryptfs_unlocked_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 323 {
 324         struct file *lower_file = NULL;
 325         long rc = -ENOTTY;
 326
 327         if (ecryptfs_file_to_private(file))
 328                 lower_file = ecryptfs_file_to_lower(file);
 329         if (lower_file && lower_file->f_op && lower_file->f_op->unlocked_ioctl)
 330                 rc = lower_file->f_op->unlocked_ioctl(lower_file, cmd, arg);
 331         return rc;
 332 }
 333
 334 #ifdef CONFIG_COMPAT
 335 static long
 336 ecryptfs_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 337 {
 338         struct file *lower_file = NULL;
 339         long rc = -ENOIOCTLCMD;
 340
 341         if (ecryptfs_file_to_private(file))
 342                 lower_file = ecryptfs_file_to_lower(file);
 343         if (lower_file && lower_file->f_op && lower_file->f_op->compat_ioctl)
 344                 rc = lower_file->f_op->compat_ioctl(lower_file, cmd, arg);
 345         return rc;
 346 }
 347 #endif
 348
 349 const struct file_operations ecryptfs_dir_fops = {
 350         .readdir = ecryptfs_readdir,
 351         .read = generic_read_dir,
 352         .unlocked_ioctl = ecryptfs_unlocked_ioctl,
 353 #ifdef CONFIG_COMPAT
 354         .compat_ioctl = ecryptfs_compat_ioctl,
 355 #endif
 356         .open = ecryptfs_open,
 357         .flush = ecryptfs_flush,
 358         .release = ecryptfs_release,
 359         .fsync = ecryptfs_fsync,
 360         .fasync = ecryptfs_fasync,
 361         .splice_read = generic_file_splice_read,
 362         .llseek = default_llseek,
 363 };
 364
 365 const struct file_operations ecryptfs_main_fops = {
 366         .llseek = generic_file_llseek,
 367         .read = do_sync_read,
 368         .aio_read = ecryptfs_read_update_atime,
 369         .write = do_sync_write,
 370         .aio_write = generic_file_aio_write,
 371         .readdir = ecryptfs_readdir,
 372         .unlocked_ioctl = ecryptfs_unlocked_ioctl,
 373 #ifdef CONFIG_COMPAT
 374         .compat_ioctl = ecryptfs_compat_ioctl,
 375 #endif
 376         .mmap = ecryptfs_mmap,
 377         .open = ecryptfs_open,
 378         .flush = ecryptfs_flush,
 379         .release = ecryptfs_release,
 380         .fsync = ecryptfs_fsync,
 381         .fasync = ecryptfs_fasync,
 382         .splice_read = generic_file_splice_read,
 383 };