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                 printk(KERN_ERR "%s: Error attempting to decode and decrypt "
  86                        "filename [%s]; rc = [%d]\n", __func__, lower_name,
  87                        rc);
  88                 goto out;
  89         }
  90         buf->caller->pos = buf->ctx.pos;
  91         rc = !dir_emit(buf->caller, name, name_size, ino, d_type);
  92         kfree(name);
  93         if (!rc)
  94                 buf->entries_written++;
  95 out:
  96         return rc;
  97 }
  98
  99 /**
 100  * ecryptfs_readdir
 101  * @file: The eCryptfs directory file
 102  * @ctx: The actor to feed the entries to
 103  */
 104 static int ecryptfs_readdir(struct file *file, struct dir_context *ctx)
 105 {
 106         int rc;
 107         struct file *lower_file;
 108         struct inode *inode = file_inode(file);
 109         struct ecryptfs_getdents_callback buf = {
 110                 .ctx.actor = ecryptfs_filldir,
 111                 .caller = ctx,
 112                 .sb = inode->i_sb,
 113         };
 114         lower_file = ecryptfs_file_to_lower(file);
 115         rc = iterate_dir(lower_file, &buf.ctx);
 116         ctx->pos = buf.ctx.pos;
 117         if (rc < 0)
 118                 goto out;
 119         if (buf.filldir_called && !buf.entries_written)
 120                 goto out;
 121         if (rc >= 0)
 122                 fsstack_copy_attr_atime(inode,
 123                                         file_inode(lower_file));
 124 out:
 125         return rc;
 126 }
 127
 128 struct kmem_cache *ecryptfs_file_info_cache;
 129
 130 static int read_or_initialize_metadata(struct dentry *dentry)
 131 {
 132         struct inode *inode = d_inode(dentry);
 133         struct ecryptfs_mount_crypt_stat *mount_crypt_stat;
 134         struct ecryptfs_crypt_stat *crypt_stat;
 135         int rc;
 136
 137         crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat;
 138         mount_crypt_stat = &ecryptfs_superblock_to_private(
 139                                                 inode->i_sb)->mount_crypt_stat;
 140         mutex_lock(&crypt_stat->cs_mutex);
 141
 142         if (crypt_stat->flags & ECRYPTFS_POLICY_APPLIED &&
 143             crypt_stat->flags & ECRYPTFS_KEY_VALID) {
 144                 rc = 0;
 145                 goto out;
 146         }
 147
 148         rc = ecryptfs_read_metadata(dentry);
 149         if (!rc)
 150                 goto out;
 151
 152         if (mount_crypt_stat->flags & ECRYPTFS_PLAINTEXT_PASSTHROUGH_ENABLED) {
 153                 crypt_stat->flags &= ~(ECRYPTFS_I_SIZE_INITIALIZED
 154                                        | ECRYPTFS_ENCRYPTED);
 155                 rc = 0;
 156                 goto out;
 157         }
 158
 159         if (!(mount_crypt_stat->flags & ECRYPTFS_XATTR_METADATA_ENABLED) &&
 160             !i_size_read(ecryptfs_inode_to_lower(inode))) {
 161                 rc = ecryptfs_initialize_file(dentry, inode);
 162                 if (!rc)
 163                         goto out;
 164         }
 165
 166         rc = -EIO;
 167 out:
 168         mutex_unlock(&crypt_stat->cs_mutex);
 169         return rc;
 170 }
 171
 172 static int ecryptfs_mmap(struct file *file, struct vm_area_struct *vma)
 173 {
 174         struct file *lower_file = ecryptfs_file_to_lower(file);
 175         /*
 176          * Don't allow mmap on top of file systems that don't support it
 177          * natively.  If FILESYSTEM_MAX_STACK_DEPTH > 2 or ecryptfs
 178          * allows recursive mounting, this will need to be extended.
 179          */
 180         if (!lower_file->f_op->mmap)
 181                 return -ENODEV;
 182         return generic_file_mmap(file, vma);
 183 }
 184
 185 /**
 186  * ecryptfs_open
 187  * @inode: inode specifying file to open
 188  * @file: Structure to return filled in
 189  *
 190  * Opens the file specified by inode.
 191  *
 192  * Returns zero on success; non-zero otherwise
 193  */
 194 static int ecryptfs_open(struct inode *inode, struct file *file)
 195 {
 196         int rc = 0;
 197         struct ecryptfs_crypt_stat *crypt_stat = NULL;
 198         struct dentry *ecryptfs_dentry = file->f_path.dentry;
 199         /* Private value of ecryptfs_dentry allocated in
 200          * ecryptfs_lookup() */
 201         struct ecryptfs_file_info *file_info;
 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         crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat;
 213         mutex_lock(&crypt_stat->cs_mutex);
 214         if (!(crypt_stat->flags & ECRYPTFS_POLICY_APPLIED)) {
 215                 ecryptfs_printk(KERN_DEBUG, "Setting flags for stat...\n");
 216                 /* Policy code enabled in future release */
 217                 crypt_stat->flags |= (ECRYPTFS_POLICY_APPLIED
 218                                       | ECRYPTFS_ENCRYPTED);
 219         }
 220         mutex_unlock(&crypt_stat->cs_mutex);
 221         rc = ecryptfs_get_lower_file(ecryptfs_dentry, inode);
 222         if (rc) {
 223                 printk(KERN_ERR "%s: Error attempting to initialize "
 224                         "the lower file for the dentry with name "
 225                         "[%pd]; rc = [%d]\n", __func__,
 226                         ecryptfs_dentry, rc);
 227                 goto out_free;
 228         }
 229         if ((ecryptfs_inode_to_private(inode)->lower_file->f_flags & O_ACCMODE)
 230             == O_RDONLY && (file->f_flags & O_ACCMODE) != O_RDONLY) {
 231                 rc = -EPERM;
 232                 printk(KERN_WARNING "%s: Lower file is RO; eCryptfs "
 233                        "file must hence be opened RO\n", __func__);
 234                 goto out_put;
 235         }
 236         ecryptfs_set_file_lower(
 237                 file, ecryptfs_inode_to_private(inode)->lower_file);
 238         rc = read_or_initialize_metadata(ecryptfs_dentry);
 239         if (rc)
 240                 goto out_put;
 241         ecryptfs_printk(KERN_DEBUG, "inode w/ addr = [0x%p], i_ino = "
 242                         "[0x%.16lx] size: [0x%.16llx]\n", inode, inode->i_ino,
 243                         (unsigned long long)i_size_read(inode));
 244         goto out;
 245 out_put:
 246         ecryptfs_put_lower_file(inode);
 247 out_free:
 248         kmem_cache_free(ecryptfs_file_info_cache,
 249                         ecryptfs_file_to_private(file));
 250 out:
 251         return rc;
 252 }
 253
 254 /**
 255  * ecryptfs_dir_open
 256  * @inode: inode specifying file to open
 257  * @file: Structure to return filled in
 258  *
 259  * Opens the file specified by inode.
 260  *
 261  * Returns zero on success; non-zero otherwise
 262  */
 263 static int ecryptfs_dir_open(struct inode *inode, struct file *file)
 264 {
 265         struct dentry *ecryptfs_dentry = file->f_path.dentry;
 266         /* Private value of ecryptfs_dentry allocated in
 267          * ecryptfs_lookup() */
 268         struct ecryptfs_file_info *file_info;
 269         struct file *lower_file;
 270
 271         /* Released in ecryptfs_release or end of function if failure */
 272         file_info = kmem_cache_zalloc(ecryptfs_file_info_cache, GFP_KERNEL);
 273         ecryptfs_set_file_private(file, file_info);
 274         if (unlikely(!file_info)) {
 275                 ecryptfs_printk(KERN_ERR,
 276                                 "Error attempting to allocate memory\n");
 277                 return -ENOMEM;
 278         }
 279         lower_file = dentry_open(ecryptfs_dentry_to_lower_path(ecryptfs_dentry),
 280                                  file->f_flags, current_cred());
 281         if (IS_ERR(lower_file)) {
 282                 printk(KERN_ERR "%s: Error attempting to initialize "
 283                         "the lower file for the dentry with name "
 284                         "[%pd]; rc = [%ld]\n", __func__,
 285                         ecryptfs_dentry, PTR_ERR(lower_file));
 286                 kmem_cache_free(ecryptfs_file_info_cache, file_info);
 287                 return PTR_ERR(lower_file);
 288         }
 289         ecryptfs_set_file_lower(file, lower_file);
 290         return 0;
 291 }
 292
 293 static int ecryptfs_flush(struct file *file, fl_owner_t td)
 294 {
 295         struct file *lower_file = ecryptfs_file_to_lower(file);
 296
 297         if (lower_file->f_op->flush) {
 298                 filemap_write_and_wait(file->f_mapping);
 299                 return lower_file->f_op->flush(lower_file, td);
 300         }
 301
 302         return 0;
 303 }
 304
 305 static int ecryptfs_release(struct inode *inode, struct file *file)
 306 {
 307         ecryptfs_put_lower_file(inode);
 308         kmem_cache_free(ecryptfs_file_info_cache,
 309                         ecryptfs_file_to_private(file));
 310         return 0;
 311 }
 312
 313 static int ecryptfs_dir_release(struct inode *inode, struct file *file)
 314 {
 315         fput(ecryptfs_file_to_lower(file));
 316         kmem_cache_free(ecryptfs_file_info_cache,
 317                         ecryptfs_file_to_private(file));
 318         return 0;
 319 }
 320
 321 static loff_t ecryptfs_dir_llseek(struct file *file, loff_t offset, int whence)
 322 {
 323         return vfs_llseek(ecryptfs_file_to_lower(file), offset, whence);
 324 }
 325
 326 static int
 327 ecryptfs_fsync(struct file *file, loff_t start, loff_t end, int datasync)
 328 {
 329         int rc;
 330
 331         rc = filemap_write_and_wait(file->f_mapping);
 332         if (rc)
 333                 return rc;
 334
 335         return vfs_fsync(ecryptfs_file_to_lower(file), datasync);
 336 }
 337
 338 static int ecryptfs_fasync(int fd, struct file *file, int flag)
 339 {
 340         int rc = 0;
 341         struct file *lower_file = NULL;
 342
 343         lower_file = ecryptfs_file_to_lower(file);
 344         if (lower_file->f_op->fasync)
 345                 rc = lower_file->f_op->fasync(fd, lower_file, flag);
 346         return rc;
 347 }
 348
 349 static long
 350 ecryptfs_unlocked_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 351 {
 352         struct file *lower_file = ecryptfs_file_to_lower(file);
 353         long rc = -ENOTTY;
 354
 355         if (!lower_file->f_op->unlocked_ioctl)
 356                 return rc;
 357
 358         switch (cmd) {
 359         case FITRIM:
 360         case FS_IOC_GETFLAGS:
 361         case FS_IOC_SETFLAGS:
 362         case FS_IOC_GETVERSION:
 363         case FS_IOC_SETVERSION:
 364                 rc = lower_file->f_op->unlocked_ioctl(lower_file, cmd, arg);
 365                 fsstack_copy_attr_all(file_inode(file), file_inode(lower_file));
 366
 367                 return rc;
 368         default:
 369                 return rc;
 370         }
 371 }
 372
 373 #ifdef CONFIG_COMPAT
 374 static long
 375 ecryptfs_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 376 {
 377         struct file *lower_file = ecryptfs_file_to_lower(file);
 378         long rc = -ENOIOCTLCMD;
 379
 380         if (!lower_file->f_op->compat_ioctl)
 381                 return rc;
 382
 383         switch (cmd) {
 384         case FS_IOC32_GETFLAGS:
 385         case FS_IOC32_SETFLAGS:
 386         case FS_IOC32_GETVERSION:
 387         case FS_IOC32_SETVERSION:
 388                 rc = lower_file->f_op->compat_ioctl(lower_file, cmd, arg);
 389                 fsstack_copy_attr_all(file_inode(file), file_inode(lower_file));
 390
 391                 return rc;
 392         default:
 393                 return rc;
 394         }
 395 }
 396 #endif
 397
 398 const struct file_operations ecryptfs_dir_fops = {
 399         .iterate_shared = ecryptfs_readdir,
 400         .read = generic_read_dir,
 401         .unlocked_ioctl = ecryptfs_unlocked_ioctl,
 402 #ifdef CONFIG_COMPAT
 403         .compat_ioctl = ecryptfs_compat_ioctl,
 404 #endif
 405         .open = ecryptfs_dir_open,
 406         .release = ecryptfs_dir_release,
 407         .fsync = ecryptfs_fsync,
 408         .llseek = ecryptfs_dir_llseek,
 409 };
 410
 411 const struct file_operations ecryptfs_main_fops = {
 412         .llseek = generic_file_llseek,
 413         .read_iter = ecryptfs_read_update_atime,
 414         .write_iter = generic_file_write_iter,
 415         .unlocked_ioctl = ecryptfs_unlocked_ioctl,
 416 #ifdef CONFIG_COMPAT
 417         .compat_ioctl = ecryptfs_compat_ioctl,
 418 #endif
 419         .mmap = ecryptfs_mmap,
 420         .open = ecryptfs_open,
 421         .flush = ecryptfs_flush,
 422         .release = ecryptfs_release,
 423         .fsync = ecryptfs_fsync,
 424         .fasync = ecryptfs_fasync,
 425         .splice_read = generic_file_splice_read,
 426 };