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 "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                                 struct iov_iter *to)
  48 {
  49         ssize_t rc;
  50         struct path *path;
  51         struct file *file = iocb->ki_filp;
  52
  53         rc = generic_file_read_iter(iocb, to);
  54         if (rc >= 0) {
  55                 path = ecryptfs_dentry_to_lower_path(file->f_path.dentry);
  56                 touch_atime(path);
  57         }
  58         return rc;
  59 }
  60
  61 struct ecryptfs_getdents_callback {
  62         struct dir_context ctx;
  63         struct dir_context *caller;
  64         struct super_block *sb;
  65         int filldir_called;
  66         int entries_written;
  67 };
  68
  69 /* Inspired by generic filldir in fs/readdir.c */
  70 static int
  71 ecryptfs_filldir(struct dir_context *ctx, const char *lower_name,
  72                  int lower_namelen, loff_t offset, u64 ino, unsigned int d_type)
  73 {
  74         struct ecryptfs_getdents_callback *buf =
  75                 container_of(ctx, struct ecryptfs_getdents_callback, ctx);
  76         size_t name_size;
  77         char *name;
  78         int rc;
  79
  80         buf->filldir_called++;
  81         rc = ecryptfs_decode_and_decrypt_filename(&name, &name_size,
  82                                                   buf->sb, lower_name,
  83                                                   lower_namelen);
  84         if (rc) {
  85                 if (rc != -EINVAL) {
  86                         ecryptfs_printk(KERN_DEBUG,
  87                                         "%s: Error attempting to decode and decrypt filename [%s]; rc = [%d]\n",
  88                                         __func__, lower_name, rc);
  89                         return rc;
  90                 }
  91
  92                 /* Mask -EINVAL errors as these are most likely due a plaintext
  93                  * filename present in the lower filesystem despite filename
  94                  * encryption being enabled. One unavoidable example would be
  95                  * the "lost+found" dentry in the root directory of an Ext4
  96                  * filesystem.
  97                  */
  98                 return 0;
  99         }
 100
 101         buf->caller->pos = buf->ctx.pos;
 102         rc = !dir_emit(buf->caller, name, name_size, ino, d_type);
 103         kfree(name);
 104         if (!rc)
 105                 buf->entries_written++;
 106
 107         return rc;
 108 }
 109
 110 /**
 111  * ecryptfs_readdir
 112  * @file: The eCryptfs directory file
 113  * @ctx: The actor to feed the entries to
 114  */
 115 static int ecryptfs_readdir(struct file *file, struct dir_context *ctx)
 116 {
 117         int rc;
 118         struct file *lower_file;
 119         struct inode *inode = file_inode(file);
 120         struct ecryptfs_getdents_callback buf = {
 121                 .ctx.actor = ecryptfs_filldir,
 122                 .caller = ctx,
 123                 .sb = inode->i_sb,
 124         };
 125         lower_file = ecryptfs_file_to_lower(file);
 126         rc = iterate_dir(lower_file, &buf.ctx);
 127         ctx->pos = buf.ctx.pos;
 128         if (rc < 0)
 129                 goto out;
 130         if (buf.filldir_called && !buf.entries_written)
 131                 goto out;
 132         if (rc >= 0)
 133                 fsstack_copy_attr_atime(inode,
 134                                         file_inode(lower_file));
 135 out:
 136         return rc;
 137 }
 138
 139 struct kmem_cache *ecryptfs_file_info_cache;
 140
 141 static int read_or_initialize_metadata(struct dentry *dentry)
 142 {
 143         struct inode *inode = d_inode(dentry);
 144         struct ecryptfs_mount_crypt_stat *mount_crypt_stat;
 145         struct ecryptfs_crypt_stat *crypt_stat;
 146         int rc;
 147
 148         crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat;
 149         mount_crypt_stat = &ecryptfs_superblock_to_private(
 150                                                 inode->i_sb)->mount_crypt_stat;
 151         mutex_lock(&crypt_stat->cs_mutex);
 152
 153         if (crypt_stat->flags & ECRYPTFS_POLICY_APPLIED &&
 154             crypt_stat->flags & ECRYPTFS_KEY_VALID) {
 155                 rc = 0;
 156                 goto out;
 157         }
 158
 159         rc = ecryptfs_read_metadata(dentry);
 160         if (!rc)
 161                 goto out;
 162
 163         if (mount_crypt_stat->flags & ECRYPTFS_PLAINTEXT_PASSTHROUGH_ENABLED) {
 164                 crypt_stat->flags &= ~(ECRYPTFS_I_SIZE_INITIALIZED
 165                                        | ECRYPTFS_ENCRYPTED);
 166                 rc = 0;
 167                 goto out;
 168         }
 169
 170         if (!(mount_crypt_stat->flags & ECRYPTFS_XATTR_METADATA_ENABLED) &&
 171             !i_size_read(ecryptfs_inode_to_lower(inode))) {
 172                 rc = ecryptfs_initialize_file(dentry, inode);
 173                 if (!rc)
 174                         goto out;
 175         }
 176
 177         rc = -EIO;
 178 out:
 179         mutex_unlock(&crypt_stat->cs_mutex);
 180         return rc;
 181 }
 182
 183 static int ecryptfs_mmap(struct file *file, struct vm_area_struct *vma)
 184 {
 185         struct file *lower_file = ecryptfs_file_to_lower(file);
 186         /*
 187          * Don't allow mmap on top of file systems that don't support it
 188          * natively.  If FILESYSTEM_MAX_STACK_DEPTH > 2 or ecryptfs
 189          * allows recursive mounting, this will need to be extended.
 190          */
 191         if (!lower_file->f_op->mmap)
 192                 return -ENODEV;
 193         return generic_file_mmap(file, vma);
 194 }
 195
 196 /**
 197  * ecryptfs_open
 198  * @inode: inode specifying file to open
 199  * @file: Structure to return filled in
 200  *
 201  * Opens the file specified by inode.
 202  *
 203  * Returns zero on success; non-zero otherwise
 204  */
 205 static int ecryptfs_open(struct inode *inode, struct file *file)
 206 {
 207         int rc = 0;
 208         struct ecryptfs_crypt_stat *crypt_stat = NULL;
 209         struct dentry *ecryptfs_dentry = file->f_path.dentry;
 210         /* Private value of ecryptfs_dentry allocated in
 211          * ecryptfs_lookup() */
 212         struct ecryptfs_file_info *file_info;
 213
 214         /* Released in ecryptfs_release or end of function if failure */
 215         file_info = kmem_cache_zalloc(ecryptfs_file_info_cache, GFP_KERNEL);
 216         ecryptfs_set_file_private(file, file_info);
 217         if (!file_info) {
 218                 ecryptfs_printk(KERN_ERR,
 219                                 "Error attempting to allocate memory\n");
 220                 rc = -ENOMEM;
 221                 goto out;
 222         }
 223         crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat;
 224         mutex_lock(&crypt_stat->cs_mutex);
 225         if (!(crypt_stat->flags & ECRYPTFS_POLICY_APPLIED)) {
 226                 ecryptfs_printk(KERN_DEBUG, "Setting flags for stat...\n");
 227                 /* Policy code enabled in future release */
 228                 crypt_stat->flags |= (ECRYPTFS_POLICY_APPLIED
 229                                       | ECRYPTFS_ENCRYPTED);
 230         }
 231         mutex_unlock(&crypt_stat->cs_mutex);
 232         rc = ecryptfs_get_lower_file(ecryptfs_dentry, inode);
 233         if (rc) {
 234                 printk(KERN_ERR "%s: Error attempting to initialize "
 235                         "the lower file for the dentry with name "
 236                         "[%pd]; rc = [%d]\n", __func__,
 237                         ecryptfs_dentry, rc);
 238                 goto out_free;
 239         }
 240         if ((ecryptfs_inode_to_private(inode)->lower_file->f_flags & O_ACCMODE)
 241             == O_RDONLY && (file->f_flags & O_ACCMODE) != O_RDONLY) {
 242                 rc = -EPERM;
 243                 printk(KERN_WARNING "%s: Lower file is RO; eCryptfs "
 244                        "file must hence be opened RO\n", __func__);
 245                 goto out_put;
 246         }
 247         ecryptfs_set_file_lower(
 248                 file, ecryptfs_inode_to_private(inode)->lower_file);
 249         rc = read_or_initialize_metadata(ecryptfs_dentry);
 250         if (rc)
 251                 goto out_put;
 252         ecryptfs_printk(KERN_DEBUG, "inode w/ addr = [0x%p], i_ino = "
 253                         "[0x%.16lx] size: [0x%.16llx]\n", inode, inode->i_ino,
 254                         (unsigned long long)i_size_read(inode));
 255         goto out;
 256 out_put:
 257         ecryptfs_put_lower_file(inode);
 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 /**
 266  * ecryptfs_dir_open
 267  * @inode: inode specifying file to open
 268  * @file: Structure to return filled in
 269  *
 270  * Opens the file specified by inode.
 271  *
 272  * Returns zero on success; non-zero otherwise
 273  */
 274 static int ecryptfs_dir_open(struct inode *inode, struct file *file)
 275 {
 276         struct dentry *ecryptfs_dentry = file->f_path.dentry;
 277         /* Private value of ecryptfs_dentry allocated in
 278          * ecryptfs_lookup() */
 279         struct ecryptfs_file_info *file_info;
 280         struct file *lower_file;
 281
 282         /* Released in ecryptfs_release or end of function if failure */
 283         file_info = kmem_cache_zalloc(ecryptfs_file_info_cache, GFP_KERNEL);
 284         ecryptfs_set_file_private(file, file_info);
 285         if (unlikely(!file_info)) {
 286                 ecryptfs_printk(KERN_ERR,
 287                                 "Error attempting to allocate memory\n");
 288                 return -ENOMEM;
 289         }
 290         lower_file = dentry_open(ecryptfs_dentry_to_lower_path(ecryptfs_dentry),
 291                                  file->f_flags, current_cred());
 292         if (IS_ERR(lower_file)) {
 293                 printk(KERN_ERR "%s: Error attempting to initialize "
 294                         "the lower file for the dentry with name "
 295                         "[%pd]; rc = [%ld]\n", __func__,
 296                         ecryptfs_dentry, PTR_ERR(lower_file));
 297                 kmem_cache_free(ecryptfs_file_info_cache, file_info);
 298                 return PTR_ERR(lower_file);
 299         }
 300         ecryptfs_set_file_lower(file, lower_file);
 301         return 0;
 302 }
 303
 304 static int ecryptfs_flush(struct file *file, fl_owner_t td)
 305 {
 306         struct file *lower_file = ecryptfs_file_to_lower(file);
 307
 308         if (lower_file->f_op->flush) {
 309                 filemap_write_and_wait(file->f_mapping);
 310                 return lower_file->f_op->flush(lower_file, td);
 311         }
 312
 313         return 0;
 314 }
 315
 316 static int ecryptfs_release(struct inode *inode, struct file *file)
 317 {
 318         ecryptfs_put_lower_file(inode);
 319         kmem_cache_free(ecryptfs_file_info_cache,
 320                         ecryptfs_file_to_private(file));
 321         return 0;
 322 }
 323
 324 static int ecryptfs_dir_release(struct inode *inode, struct file *file)
 325 {
 326         fput(ecryptfs_file_to_lower(file));
 327         kmem_cache_free(ecryptfs_file_info_cache,
 328                         ecryptfs_file_to_private(file));
 329         return 0;
 330 }
 331
 332 static loff_t ecryptfs_dir_llseek(struct file *file, loff_t offset, int whence)
 333 {
 334         return vfs_llseek(ecryptfs_file_to_lower(file), offset, whence);
 335 }
 336
 337 static int
 338 ecryptfs_fsync(struct file *file, loff_t start, loff_t end, int datasync)
 339 {
 340         int rc;
 341
 342         rc = file_write_and_wait(file);
 343         if (rc)
 344                 return rc;
 345
 346         return vfs_fsync(ecryptfs_file_to_lower(file), datasync);
 347 }
 348
 349 static int ecryptfs_fasync(int fd, struct file *file, int flag)
 350 {
 351         int rc = 0;
 352         struct file *lower_file = NULL;
 353
 354         lower_file = ecryptfs_file_to_lower(file);
 355         if (lower_file->f_op->fasync)
 356                 rc = lower_file->f_op->fasync(fd, lower_file, flag);
 357         return rc;
 358 }
 359
 360 static long
 361 ecryptfs_unlocked_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 362 {
 363         struct file *lower_file = ecryptfs_file_to_lower(file);
 364         long rc = -ENOTTY;
 365
 366         if (!lower_file->f_op->unlocked_ioctl)
 367                 return rc;
 368
 369         switch (cmd) {
 370         case FITRIM:
 371         case FS_IOC_GETFLAGS:
 372         case FS_IOC_SETFLAGS:
 373         case FS_IOC_GETVERSION:
 374         case FS_IOC_SETVERSION:
 375                 rc = lower_file->f_op->unlocked_ioctl(lower_file, cmd, arg);
 376                 fsstack_copy_attr_all(file_inode(file), file_inode(lower_file));
 377
 378                 return rc;
 379         default:
 380                 return rc;
 381         }
 382 }
 383
 384 #ifdef CONFIG_COMPAT
 385 static long
 386 ecryptfs_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 387 {
 388         struct file *lower_file = ecryptfs_file_to_lower(file);
 389         long rc = -ENOIOCTLCMD;
 390
 391         if (!lower_file->f_op->compat_ioctl)
 392                 return rc;
 393
 394         switch (cmd) {
 395         case FS_IOC32_GETFLAGS:
 396         case FS_IOC32_SETFLAGS:
 397         case FS_IOC32_GETVERSION:
 398         case FS_IOC32_SETVERSION:
 399                 rc = lower_file->f_op->compat_ioctl(lower_file, cmd, arg);
 400                 fsstack_copy_attr_all(file_inode(file), file_inode(lower_file));
 401
 402                 return rc;
 403         default:
 404                 return rc;
 405         }
 406 }
 407 #endif
 408
 409 const struct file_operations ecryptfs_dir_fops = {
 410         .iterate_shared = ecryptfs_readdir,
 411         .read = generic_read_dir,
 412         .unlocked_ioctl = ecryptfs_unlocked_ioctl,
 413 #ifdef CONFIG_COMPAT
 414         .compat_ioctl = ecryptfs_compat_ioctl,
 415 #endif
 416         .open = ecryptfs_dir_open,
 417         .release = ecryptfs_dir_release,
 418         .fsync = ecryptfs_fsync,
 419         .llseek = ecryptfs_dir_llseek,
 420 };
 421
 422 const struct file_operations ecryptfs_main_fops = {
 423         .llseek = generic_file_llseek,
 424         .read_iter = ecryptfs_read_update_atime,
 425         .write_iter = generic_file_write_iter,
 426         .unlocked_ioctl = ecryptfs_unlocked_ioctl,
 427 #ifdef CONFIG_COMPAT
 428         .compat_ioctl = ecryptfs_compat_ioctl,
 429 #endif
 430         .mmap = ecryptfs_mmap,
 431         .open = ecryptfs_open,
 432         .flush = ecryptfs_flush,
 433         .release = ecryptfs_release,
 434         .fsync = ecryptfs_fsync,
 435         .fasync = ecryptfs_fasync,
 436         .splice_read = generic_file_splice_read,
 437 };