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 *path;
  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                 path = ecryptfs_dentry_to_lower_path(file->f_path.dentry);
  64                 touch_atime(path);
  65         }
  66         return rc;
  67 }
  68
  69 struct ecryptfs_getdents_callback {
  70         struct dir_context ctx;
  71         struct dir_context *caller;
  72         struct super_block *sb;
  73         int filldir_called;
  74         int entries_written;
  75 };
  76
  77 /* Inspired by generic filldir in fs/readdir.c */
  78 static int
  79 ecryptfs_filldir(void *dirent, const char *lower_name, int lower_namelen,
  80                  loff_t offset, u64 ino, unsigned int d_type)
  81 {
  82         struct ecryptfs_getdents_callback *buf =
  83             (struct ecryptfs_getdents_callback *)dirent;
  84         size_t name_size;
  85         char *name;
  86         int rc;
  87
  88         buf->filldir_called++;
  89         rc = ecryptfs_decode_and_decrypt_filename(&name, &name_size,
  90                                                   buf->sb, lower_name,
  91                                                   lower_namelen);
  92         if (rc) {
  93                 printk(KERN_ERR "%s: Error attempting to decode and decrypt "
  94                        "filename [%s]; rc = [%d]\n", __func__, lower_name,
  95                        rc);
  96                 goto out;
  97         }
  98         buf->caller->pos = buf->ctx.pos;
  99         rc = !dir_emit(buf->caller, name, name_size, ino, d_type);
 100         kfree(name);
 101         if (!rc)
 102                 buf->entries_written++;
 103 out:
 104         return rc;
 105 }
 106
 107 /**
 108  * ecryptfs_readdir
 109  * @file: The eCryptfs directory file
 110  * @ctx: The actor to feed the entries to
 111  */
 112 static int ecryptfs_readdir(struct file *file, struct dir_context *ctx)
 113 {
 114         int rc;
 115         struct file *lower_file;
 116         struct inode *inode = file_inode(file);
 117         struct ecryptfs_getdents_callback buf = {
 118                 .ctx.actor = ecryptfs_filldir,
 119                 .caller = ctx,
 120                 .sb = inode->i_sb,
 121         };
 122         lower_file = ecryptfs_file_to_lower(file);
 123         lower_file->f_pos = ctx->pos;
 124         rc = iterate_dir(lower_file, &buf.ctx);
 125         ctx->pos = buf.ctx.pos;
 126         if (rc < 0)
 127                 goto out;
 128         if (buf.filldir_called && !buf.entries_written)
 129                 goto out;
 130         if (rc >= 0)
 131                 fsstack_copy_attr_atime(inode,
 132                                         file_inode(lower_file));
 133 out:
 134         return rc;
 135 }
 136
 137 struct kmem_cache *ecryptfs_file_info_cache;
 138
 139 static int read_or_initialize_metadata(struct dentry *dentry)
 140 {
 141         struct inode *inode = dentry->d_inode;
 142         struct ecryptfs_mount_crypt_stat *mount_crypt_stat;
 143         struct ecryptfs_crypt_stat *crypt_stat;
 144         int rc;
 145
 146         crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat;
 147         mount_crypt_stat = &ecryptfs_superblock_to_private(
 148                                                 inode->i_sb)->mount_crypt_stat;
 149         mutex_lock(&crypt_stat->cs_mutex);
 150
 151         if (crypt_stat->flags & ECRYPTFS_POLICY_APPLIED &&
 152             crypt_stat->flags & ECRYPTFS_KEY_VALID) {
 153                 rc = 0;
 154                 goto out;
 155         }
 156
 157         rc = ecryptfs_read_metadata(dentry);
 158         if (!rc)
 159                 goto out;
 160
 161         if (mount_crypt_stat->flags & ECRYPTFS_PLAINTEXT_PASSTHROUGH_ENABLED) {
 162                 crypt_stat->flags &= ~(ECRYPTFS_I_SIZE_INITIALIZED
 163                                        | ECRYPTFS_ENCRYPTED);
 164                 rc = 0;
 165                 goto out;
 166         }
 167
 168         if (!(mount_crypt_stat->flags & ECRYPTFS_XATTR_METADATA_ENABLED) &&
 169             !i_size_read(ecryptfs_inode_to_lower(inode))) {
 170                 rc = ecryptfs_initialize_file(dentry, inode);
 171                 if (!rc)
 172                         goto out;
 173         }
 174
 175         rc = -EIO;
 176 out:
 177         mutex_unlock(&crypt_stat->cs_mutex);
 178         return rc;
 179 }
 180
 181 /**
 182  * ecryptfs_open
 183  * @inode: inode speciying file to open
 184  * @file: Structure to return filled in
 185  *
 186  * Opens the file specified by inode.
 187  *
 188  * Returns zero on success; non-zero otherwise
 189  */
 190 static int ecryptfs_open(struct inode *inode, struct file *file)
 191 {
 192         int rc = 0;
 193         struct ecryptfs_crypt_stat *crypt_stat = NULL;
 194         struct ecryptfs_mount_crypt_stat *mount_crypt_stat;
 195         struct dentry *ecryptfs_dentry = file->f_path.dentry;
 196         /* Private value of ecryptfs_dentry allocated in
 197          * ecryptfs_lookup() */
 198         struct ecryptfs_file_info *file_info;
 199
 200         mount_crypt_stat = &ecryptfs_superblock_to_private(
 201                 ecryptfs_dentry->d_sb)->mount_crypt_stat;
 202         if ((mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED)
 203             && ((file->f_flags & O_WRONLY) || (file->f_flags & O_RDWR)
 204                 || (file->f_flags & O_CREAT) || (file->f_flags & O_TRUNC)
 205                 || (file->f_flags & O_APPEND))) {
 206                 printk(KERN_WARNING "Mount has encrypted view enabled; "
 207                        "files may only be read\n");
 208                 rc = -EPERM;
 209                 goto out;
 210         }
 211         /* Released in ecryptfs_release or end of function if failure */
 212         file_info = kmem_cache_zalloc(ecryptfs_file_info_cache, GFP_KERNEL);
 213         ecryptfs_set_file_private(file, file_info);
 214         if (!file_info) {
 215                 ecryptfs_printk(KERN_ERR,
 216                                 "Error attempting to allocate memory\n");
 217                 rc = -ENOMEM;
 218                 goto out;
 219         }
 220         crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat;
 221         mutex_lock(&crypt_stat->cs_mutex);
 222         if (!(crypt_stat->flags & ECRYPTFS_POLICY_APPLIED)) {
 223                 ecryptfs_printk(KERN_DEBUG, "Setting flags for stat...\n");
 224                 /* Policy code enabled in future release */
 225                 crypt_stat->flags |= (ECRYPTFS_POLICY_APPLIED
 226                                       | ECRYPTFS_ENCRYPTED);
 227         }
 228         mutex_unlock(&crypt_stat->cs_mutex);
 229         rc = ecryptfs_get_lower_file(ecryptfs_dentry, inode);
 230         if (rc) {
 231                 printk(KERN_ERR "%s: Error attempting to initialize "
 232                         "the lower file for the dentry with name "
 233                         "[%s]; rc = [%d]\n", __func__,
 234                         ecryptfs_dentry->d_name.name, rc);
 235                 goto out_free;
 236         }
 237         if ((ecryptfs_inode_to_private(inode)->lower_file->f_flags & O_ACCMODE)
 238             == O_RDONLY && (file->f_flags & O_ACCMODE) != O_RDONLY) {
 239                 rc = -EPERM;
 240                 printk(KERN_WARNING "%s: Lower file is RO; eCryptfs "
 241                        "file must hence be opened RO\n", __func__);
 242                 goto out_put;
 243         }
 244         ecryptfs_set_file_lower(
 245                 file, ecryptfs_inode_to_private(inode)->lower_file);
 246         if (S_ISDIR(ecryptfs_dentry->d_inode->i_mode)) {
 247                 ecryptfs_printk(KERN_DEBUG, "This is a directory\n");
 248                 mutex_lock(&crypt_stat->cs_mutex);
 249                 crypt_stat->flags &= ~(ECRYPTFS_ENCRYPTED);
 250                 mutex_unlock(&crypt_stat->cs_mutex);
 251                 rc = 0;
 252                 goto out;
 253         }
 254         rc = read_or_initialize_metadata(ecryptfs_dentry);
 255         if (rc)
 256                 goto out_put;
 257         ecryptfs_printk(KERN_DEBUG, "inode w/ addr = [0x%p], i_ino = "
 258                         "[0x%.16lx] size: [0x%.16llx]\n", inode, inode->i_ino,
 259                         (unsigned long long)i_size_read(inode));
 260         goto out;
 261 out_put:
 262         ecryptfs_put_lower_file(inode);
 263 out_free:
 264         kmem_cache_free(ecryptfs_file_info_cache,
 265                         ecryptfs_file_to_private(file));
 266 out:
 267         return rc;
 268 }
 269
 270 static int ecryptfs_flush(struct file *file, fl_owner_t td)
 271 {
 272         struct file *lower_file = ecryptfs_file_to_lower(file);
 273
 274         if (lower_file->f_op->flush) {
 275                 filemap_write_and_wait(file->f_mapping);
 276                 return lower_file->f_op->flush(lower_file, td);
 277         }
 278
 279         return 0;
 280 }
 281
 282 static int ecryptfs_release(struct inode *inode, struct file *file)
 283 {
 284         ecryptfs_put_lower_file(inode);
 285         kmem_cache_free(ecryptfs_file_info_cache,
 286                         ecryptfs_file_to_private(file));
 287         return 0;
 288 }
 289
 290 static int
 291 ecryptfs_fsync(struct file *file, loff_t start, loff_t end, int datasync)
 292 {
 293         int rc;
 294
 295         rc = filemap_write_and_wait(file->f_mapping);
 296         if (rc)
 297                 return rc;
 298
 299         return vfs_fsync(ecryptfs_file_to_lower(file), datasync);
 300 }
 301
 302 static int ecryptfs_fasync(int fd, struct file *file, int flag)
 303 {
 304         int rc = 0;
 305         struct file *lower_file = NULL;
 306
 307         lower_file = ecryptfs_file_to_lower(file);
 308         if (lower_file->f_op->fasync)
 309                 rc = lower_file->f_op->fasync(fd, lower_file, flag);
 310         return rc;
 311 }
 312
 313 static long
 314 ecryptfs_unlocked_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 315 {
 316         struct file *lower_file = ecryptfs_file_to_lower(file);
 317         long rc = -ENOTTY;
 318
 319         if (lower_file->f_op->unlocked_ioctl)
 320                 rc = lower_file->f_op->unlocked_ioctl(lower_file, cmd, arg);
 321         return rc;
 322 }
 323
 324 #ifdef CONFIG_COMPAT
 325 static long
 326 ecryptfs_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 327 {
 328         struct file *lower_file = ecryptfs_file_to_lower(file);
 329         long rc = -ENOIOCTLCMD;
 330
 331         if (lower_file->f_op && lower_file->f_op->compat_ioctl)
 332                 rc = lower_file->f_op->compat_ioctl(lower_file, cmd, arg);
 333         return rc;
 334 }
 335 #endif
 336
 337 const struct file_operations ecryptfs_dir_fops = {
 338         .iterate = ecryptfs_readdir,
 339         .read = generic_read_dir,
 340         .unlocked_ioctl = ecryptfs_unlocked_ioctl,
 341 #ifdef CONFIG_COMPAT
 342         .compat_ioctl = ecryptfs_compat_ioctl,
 343 #endif
 344         .open = ecryptfs_open,
 345         .flush = ecryptfs_flush,
 346         .release = ecryptfs_release,
 347         .fsync = ecryptfs_fsync,
 348         .fasync = ecryptfs_fasync,
 349         .splice_read = generic_file_splice_read,
 350         .llseek = default_llseek,
 351 };
 352
 353 const struct file_operations ecryptfs_main_fops = {
 354         .llseek = generic_file_llseek,
 355         .read = do_sync_read,
 356         .aio_read = ecryptfs_read_update_atime,
 357         .write = do_sync_write,
 358         .aio_write = generic_file_aio_write,
 359         .iterate = ecryptfs_readdir,
 360         .unlocked_ioctl = ecryptfs_unlocked_ioctl,
 361 #ifdef CONFIG_COMPAT
 362         .compat_ioctl = ecryptfs_compat_ioctl,
 363 #endif
 364         .mmap = generic_file_mmap,
 365         .open = ecryptfs_open,
 366         .flush = ecryptfs_flush,
 367         .release = ecryptfs_release,
 368         .fsync = ecryptfs_fsync,
 369         .fasync = ecryptfs_fasync,
 370         .splice_read = generic_file_splice_read,
 371 };