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         struct dir_context *caller;
  73         struct super_block *sb;
  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->sb, 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         buf->caller->pos = buf->ctx.pos;
 100         rc = !dir_emit(buf->caller, name, name_size, ino, d_type);
 101         kfree(name);
 102         if (!rc)
 103                 buf->entries_written++;
 104 out:
 105         return rc;
 106 }
 107
 108 /**
 109  * ecryptfs_readdir
 110  * @file: The eCryptfs directory file
 111  * @ctx: The actor to feed the entries to
 112  */
 113 static int ecryptfs_readdir(struct file *file, struct dir_context *ctx)
 114 {
 115         int rc;
 116         struct file *lower_file;
 117         struct inode *inode = file_inode(file);
 118         struct ecryptfs_getdents_callback buf = {
 119                 .ctx.actor = ecryptfs_filldir,
 120                 .caller = ctx,
 121                 .sb = inode->i_sb,
 122         };
 123         lower_file = ecryptfs_file_to_lower(file);
 124         lower_file->f_pos = ctx->pos;
 125         rc = iterate_dir(lower_file, &buf.ctx);
 126         ctx->pos = buf.ctx.pos;
 127         if (rc < 0)
 128                 goto out;
 129         if (buf.filldir_called && !buf.entries_written)
 130                 goto out;
 131         if (rc >= 0)
 132                 fsstack_copy_attr_atime(inode,
 133                                         file_inode(lower_file));
 134 out:
 135         return rc;
 136 }
 137
 138 struct kmem_cache *ecryptfs_file_info_cache;
 139
 140 static int read_or_initialize_metadata(struct dentry *dentry)
 141 {
 142         struct inode *inode = dentry->d_inode;
 143         struct ecryptfs_mount_crypt_stat *mount_crypt_stat;
 144         struct ecryptfs_crypt_stat *crypt_stat;
 145         int rc;
 146
 147         crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat;
 148         mount_crypt_stat = &ecryptfs_superblock_to_private(
 149                                                 inode->i_sb)->mount_crypt_stat;
 150         mutex_lock(&crypt_stat->cs_mutex);
 151
 152         if (crypt_stat->flags & ECRYPTFS_POLICY_APPLIED &&
 153             crypt_stat->flags & ECRYPTFS_KEY_VALID) {
 154                 rc = 0;
 155                 goto out;
 156         }
 157
 158         rc = ecryptfs_read_metadata(dentry);
 159         if (!rc)
 160                 goto out;
 161
 162         if (mount_crypt_stat->flags & ECRYPTFS_PLAINTEXT_PASSTHROUGH_ENABLED) {
 163                 crypt_stat->flags &= ~(ECRYPTFS_I_SIZE_INITIALIZED
 164                                        | ECRYPTFS_ENCRYPTED);
 165                 rc = 0;
 166                 goto out;
 167         }
 168
 169         if (!(mount_crypt_stat->flags & ECRYPTFS_XATTR_METADATA_ENABLED) &&
 170             !i_size_read(ecryptfs_inode_to_lower(inode))) {
 171                 rc = ecryptfs_initialize_file(dentry, inode);
 172                 if (!rc)
 173                         goto out;
 174         }
 175
 176         rc = -EIO;
 177 out:
 178         mutex_unlock(&crypt_stat->cs_mutex);
 179         return rc;
 180 }
 181
 182 /**
 183  * ecryptfs_open
 184  * @inode: inode speciying file to open
 185  * @file: Structure to return filled in
 186  *
 187  * Opens the file specified by inode.
 188  *
 189  * Returns zero on success; non-zero otherwise
 190  */
 191 static int ecryptfs_open(struct inode *inode, struct file *file)
 192 {
 193         int rc = 0;
 194         struct ecryptfs_crypt_stat *crypt_stat = NULL;
 195         struct ecryptfs_mount_crypt_stat *mount_crypt_stat;
 196         struct dentry *ecryptfs_dentry = file->f_path.dentry;
 197         /* Private value of ecryptfs_dentry allocated in
 198          * ecryptfs_lookup() */
 199         struct ecryptfs_file_info *file_info;
 200
 201         mount_crypt_stat = &ecryptfs_superblock_to_private(
 202                 ecryptfs_dentry->d_sb)->mount_crypt_stat;
 203         if ((mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED)
 204             && ((file->f_flags & O_WRONLY) || (file->f_flags & O_RDWR)
 205                 || (file->f_flags & O_CREAT) || (file->f_flags & O_TRUNC)
 206                 || (file->f_flags & O_APPEND))) {
 207                 printk(KERN_WARNING "Mount has encrypted view enabled; "
 208                        "files may only be read\n");
 209                 rc = -EPERM;
 210                 goto out;
 211         }
 212         /* Released in ecryptfs_release or end of function if failure */
 213         file_info = kmem_cache_zalloc(ecryptfs_file_info_cache, GFP_KERNEL);
 214         ecryptfs_set_file_private(file, file_info);
 215         if (!file_info) {
 216                 ecryptfs_printk(KERN_ERR,
 217                                 "Error attempting to allocate memory\n");
 218                 rc = -ENOMEM;
 219                 goto out;
 220         }
 221         crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat;
 222         mutex_lock(&crypt_stat->cs_mutex);
 223         if (!(crypt_stat->flags & ECRYPTFS_POLICY_APPLIED)) {
 224                 ecryptfs_printk(KERN_DEBUG, "Setting flags for stat...\n");
 225                 /* Policy code enabled in future release */
 226                 crypt_stat->flags |= (ECRYPTFS_POLICY_APPLIED
 227                                       | ECRYPTFS_ENCRYPTED);
 228         }
 229         mutex_unlock(&crypt_stat->cs_mutex);
 230         rc = ecryptfs_get_lower_file(ecryptfs_dentry, inode);
 231         if (rc) {
 232                 printk(KERN_ERR "%s: Error attempting to initialize "
 233                         "the lower file for the dentry with name "
 234                         "[%s]; rc = [%d]\n", __func__,
 235                         ecryptfs_dentry->d_name.name, rc);
 236                 goto out_free;
 237         }
 238         if ((ecryptfs_inode_to_private(inode)->lower_file->f_flags & O_ACCMODE)
 239             == O_RDONLY && (file->f_flags & O_ACCMODE) != O_RDONLY) {
 240                 rc = -EPERM;
 241                 printk(KERN_WARNING "%s: Lower file is RO; eCryptfs "
 242                        "file must hence be opened RO\n", __func__);
 243                 goto out_put;
 244         }
 245         ecryptfs_set_file_lower(
 246                 file, ecryptfs_inode_to_private(inode)->lower_file);
 247         if (S_ISDIR(ecryptfs_dentry->d_inode->i_mode)) {
 248                 ecryptfs_printk(KERN_DEBUG, "This is a directory\n");
 249                 mutex_lock(&crypt_stat->cs_mutex);
 250                 crypt_stat->flags &= ~(ECRYPTFS_ENCRYPTED);
 251                 mutex_unlock(&crypt_stat->cs_mutex);
 252                 rc = 0;
 253                 goto out;
 254         }
 255         rc = read_or_initialize_metadata(ecryptfs_dentry);
 256         if (rc)
 257                 goto out_put;
 258         ecryptfs_printk(KERN_DEBUG, "inode w/ addr = [0x%p], i_ino = "
 259                         "[0x%.16lx] size: [0x%.16llx]\n", inode, inode->i_ino,
 260                         (unsigned long long)i_size_read(inode));
 261         goto out;
 262 out_put:
 263         ecryptfs_put_lower_file(inode);
 264 out_free:
 265         kmem_cache_free(ecryptfs_file_info_cache,
 266                         ecryptfs_file_to_private(file));
 267 out:
 268         return rc;
 269 }
 270
 271 static int ecryptfs_flush(struct file *file, fl_owner_t td)
 272 {
 273         struct file *lower_file = ecryptfs_file_to_lower(file);
 274
 275         if (lower_file->f_op && lower_file->f_op->flush) {
 276                 filemap_write_and_wait(file->f_mapping);
 277                 return lower_file->f_op->flush(lower_file, td);
 278         }
 279
 280         return 0;
 281 }
 282
 283 static int ecryptfs_release(struct inode *inode, struct file *file)
 284 {
 285         ecryptfs_put_lower_file(inode);
 286         kmem_cache_free(ecryptfs_file_info_cache,
 287                         ecryptfs_file_to_private(file));
 288         return 0;
 289 }
 290
 291 static int
 292 ecryptfs_fsync(struct file *file, loff_t start, loff_t end, int datasync)
 293 {
 294         int rc;
 295
 296         rc = filemap_write_and_wait(file->f_mapping);
 297         if (rc)
 298                 return rc;
 299
 300         return vfs_fsync(ecryptfs_file_to_lower(file), datasync);
 301 }
 302
 303 static int ecryptfs_fasync(int fd, struct file *file, int flag)
 304 {
 305         int rc = 0;
 306         struct file *lower_file = NULL;
 307
 308         lower_file = ecryptfs_file_to_lower(file);
 309         if (lower_file->f_op && lower_file->f_op->fasync)
 310                 rc = lower_file->f_op->fasync(fd, lower_file, flag);
 311         return rc;
 312 }
 313
 314 static long
 315 ecryptfs_unlocked_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 316 {
 317         struct file *lower_file = NULL;
 318         long rc = -ENOTTY;
 319
 320         if (ecryptfs_file_to_private(file))
 321                 lower_file = ecryptfs_file_to_lower(file);
 322         if (lower_file && lower_file->f_op && lower_file->f_op->unlocked_ioctl)
 323                 rc = lower_file->f_op->unlocked_ioctl(lower_file, cmd, arg);
 324         return rc;
 325 }
 326
 327 #ifdef CONFIG_COMPAT
 328 static long
 329 ecryptfs_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 330 {
 331         struct file *lower_file = NULL;
 332         long rc = -ENOIOCTLCMD;
 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->compat_ioctl)
 337                 rc = lower_file->f_op->compat_ioctl(lower_file, cmd, arg);
 338         return rc;
 339 }
 340 #endif
 341
 342 const struct file_operations ecryptfs_dir_fops = {
 343         .iterate = ecryptfs_readdir,
 344         .read = generic_read_dir,
 345         .unlocked_ioctl = ecryptfs_unlocked_ioctl,
 346 #ifdef CONFIG_COMPAT
 347         .compat_ioctl = ecryptfs_compat_ioctl,
 348 #endif
 349         .open = ecryptfs_open,
 350         .flush = ecryptfs_flush,
 351         .release = ecryptfs_release,
 352         .fsync = ecryptfs_fsync,
 353         .fasync = ecryptfs_fasync,
 354         .splice_read = generic_file_splice_read,
 355         .llseek = default_llseek,
 356 };
 357
 358 const struct file_operations ecryptfs_main_fops = {
 359         .llseek = generic_file_llseek,
 360         .read = do_sync_read,
 361         .aio_read = ecryptfs_read_update_atime,
 362         .write = do_sync_write,
 363         .aio_write = generic_file_aio_write,
 364         .iterate = ecryptfs_readdir,
 365         .unlocked_ioctl = ecryptfs_unlocked_ioctl,
 366 #ifdef CONFIG_COMPAT
 367         .compat_ioctl = ecryptfs_compat_ioctl,
 368 #endif
 369         .mmap = generic_file_mmap,
 370         .open = ecryptfs_open,
 371         .flush = ecryptfs_flush,
 372         .release = ecryptfs_release,
 373         .fsync = ecryptfs_fsync,
 374         .fasync = ecryptfs_fasync,
 375         .splice_read = generic_file_splice_read,
 376 };