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         lower_file->f_pos = ctx->pos;
 116         rc = iterate_dir(lower_file, &buf.ctx);
 117         ctx->pos = buf.ctx.pos;
 118         if (rc < 0)
 119                 goto out;
 120         if (buf.filldir_called && !buf.entries_written)
 121                 goto out;
 122         if (rc >= 0)
 123                 fsstack_copy_attr_atime(inode,
 124                                         file_inode(lower_file));
 125 out:
 126         return rc;
 127 }
 128
 129 struct kmem_cache *ecryptfs_file_info_cache;
 130
 131 static int read_or_initialize_metadata(struct dentry *dentry)
 132 {
 133         struct inode *inode = d_inode(dentry);
 134         struct ecryptfs_mount_crypt_stat *mount_crypt_stat;
 135         struct ecryptfs_crypt_stat *crypt_stat;
 136         int rc;
 137
 138         crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat;
 139         mount_crypt_stat = &ecryptfs_superblock_to_private(
 140                                                 inode->i_sb)->mount_crypt_stat;
 141         mutex_lock(&crypt_stat->cs_mutex);
 142
 143         if (crypt_stat->flags & ECRYPTFS_POLICY_APPLIED &&
 144             crypt_stat->flags & ECRYPTFS_KEY_VALID) {
 145                 rc = 0;
 146                 goto out;
 147         }
 148
 149         rc = ecryptfs_read_metadata(dentry);
 150         if (!rc)
 151                 goto out;
 152
 153         if (mount_crypt_stat->flags & ECRYPTFS_PLAINTEXT_PASSTHROUGH_ENABLED) {
 154                 crypt_stat->flags &= ~(ECRYPTFS_I_SIZE_INITIALIZED
 155                                        | ECRYPTFS_ENCRYPTED);
 156                 rc = 0;
 157                 goto out;
 158         }
 159
 160         if (!(mount_crypt_stat->flags & ECRYPTFS_XATTR_METADATA_ENABLED) &&
 161             !i_size_read(ecryptfs_inode_to_lower(inode))) {
 162                 rc = ecryptfs_initialize_file(dentry, inode);
 163                 if (!rc)
 164                         goto out;
 165         }
 166
 167         rc = -EIO;
 168 out:
 169         mutex_unlock(&crypt_stat->cs_mutex);
 170         return rc;
 171 }
 172
 173 static int ecryptfs_mmap(struct file *file, struct vm_area_struct *vma)
 174 {
 175         struct file *lower_file = ecryptfs_file_to_lower(file);
 176         /*
 177          * Don't allow mmap on top of file systems that don't support it
 178          * natively.  If FILESYSTEM_MAX_STACK_DEPTH > 2 or ecryptfs
 179          * allows recursive mounting, this will need to be extended.
 180          */
 181         if (!lower_file->f_op->mmap)
 182                 return -ENODEV;
 183         return generic_file_mmap(file, vma);
 184 }
 185
 186 /**
 187  * ecryptfs_open
 188  * @inode: inode speciying file to open
 189  * @file: Structure to return filled in
 190  *
 191  * Opens the file specified by inode.
 192  *
 193  * Returns zero on success; non-zero otherwise
 194  */
 195 static int ecryptfs_open(struct inode *inode, struct file *file)
 196 {
 197         int rc = 0;
 198         struct ecryptfs_crypt_stat *crypt_stat = NULL;
 199         struct dentry *ecryptfs_dentry = file->f_path.dentry;
 200         /* Private value of ecryptfs_dentry allocated in
 201          * ecryptfs_lookup() */
 202         struct ecryptfs_file_info *file_info;
 203
 204         /* Released in ecryptfs_release or end of function if failure */
 205         file_info = kmem_cache_zalloc(ecryptfs_file_info_cache, GFP_KERNEL);
 206         ecryptfs_set_file_private(file, file_info);
 207         if (!file_info) {
 208                 ecryptfs_printk(KERN_ERR,
 209                                 "Error attempting to allocate memory\n");
 210                 rc = -ENOMEM;
 211                 goto out;
 212         }
 213         crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat;
 214         mutex_lock(&crypt_stat->cs_mutex);
 215         if (!(crypt_stat->flags & ECRYPTFS_POLICY_APPLIED)) {
 216                 ecryptfs_printk(KERN_DEBUG, "Setting flags for stat...\n");
 217                 /* Policy code enabled in future release */
 218                 crypt_stat->flags |= (ECRYPTFS_POLICY_APPLIED
 219                                       | ECRYPTFS_ENCRYPTED);
 220         }
 221         mutex_unlock(&crypt_stat->cs_mutex);
 222         rc = ecryptfs_get_lower_file(ecryptfs_dentry, inode);
 223         if (rc) {
 224                 printk(KERN_ERR "%s: Error attempting to initialize "
 225                         "the lower file for the dentry with name "
 226                         "[%pd]; rc = [%d]\n", __func__,
 227                         ecryptfs_dentry, rc);
 228                 goto out_free;
 229         }
 230         if ((ecryptfs_inode_to_private(inode)->lower_file->f_flags & O_ACCMODE)
 231             == O_RDONLY && (file->f_flags & O_ACCMODE) != O_RDONLY) {
 232                 rc = -EPERM;
 233                 printk(KERN_WARNING "%s: Lower file is RO; eCryptfs "
 234                        "file must hence be opened RO\n", __func__);
 235                 goto out_put;
 236         }
 237         ecryptfs_set_file_lower(
 238                 file, ecryptfs_inode_to_private(inode)->lower_file);
 239         if (d_is_dir(ecryptfs_dentry)) {
 240                 ecryptfs_printk(KERN_DEBUG, "This is a directory\n");
 241                 mutex_lock(&crypt_stat->cs_mutex);
 242                 crypt_stat->flags &= ~(ECRYPTFS_ENCRYPTED);
 243                 mutex_unlock(&crypt_stat->cs_mutex);
 244                 rc = 0;
 245                 goto out;
 246         }
 247         rc = read_or_initialize_metadata(ecryptfs_dentry);
 248         if (rc)
 249                 goto out_put;
 250         ecryptfs_printk(KERN_DEBUG, "inode w/ addr = [0x%p], i_ino = "
 251                         "[0x%.16lx] size: [0x%.16llx]\n", inode, inode->i_ino,
 252                         (unsigned long long)i_size_read(inode));
 253         goto out;
 254 out_put:
 255         ecryptfs_put_lower_file(inode);
 256 out_free:
 257         kmem_cache_free(ecryptfs_file_info_cache,
 258                         ecryptfs_file_to_private(file));
 259 out:
 260         return rc;
 261 }
 262
 263 static int ecryptfs_flush(struct file *file, fl_owner_t td)
 264 {
 265         struct file *lower_file = ecryptfs_file_to_lower(file);
 266
 267         if (lower_file->f_op->flush) {
 268                 filemap_write_and_wait(file->f_mapping);
 269                 return lower_file->f_op->flush(lower_file, td);
 270         }
 271
 272         return 0;
 273 }
 274
 275 static int ecryptfs_release(struct inode *inode, struct file *file)
 276 {
 277         ecryptfs_put_lower_file(inode);
 278         kmem_cache_free(ecryptfs_file_info_cache,
 279                         ecryptfs_file_to_private(file));
 280         return 0;
 281 }
 282
 283 static int
 284 ecryptfs_fsync(struct file *file, loff_t start, loff_t end, int datasync)
 285 {
 286         int rc;
 287
 288         rc = filemap_write_and_wait(file->f_mapping);
 289         if (rc)
 290                 return rc;
 291
 292         return vfs_fsync(ecryptfs_file_to_lower(file), datasync);
 293 }
 294
 295 static int ecryptfs_fasync(int fd, struct file *file, int flag)
 296 {
 297         int rc = 0;
 298         struct file *lower_file = NULL;
 299
 300         lower_file = ecryptfs_file_to_lower(file);
 301         if (lower_file->f_op->fasync)
 302                 rc = lower_file->f_op->fasync(fd, lower_file, flag);
 303         return rc;
 304 }
 305
 306 static long
 307 ecryptfs_unlocked_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 308 {
 309         struct file *lower_file = ecryptfs_file_to_lower(file);
 310         long rc = -ENOTTY;
 311
 312         if (!lower_file->f_op->unlocked_ioctl)
 313                 return rc;
 314
 315         switch (cmd) {
 316         case FITRIM:
 317         case FS_IOC_GETFLAGS:
 318         case FS_IOC_SETFLAGS:
 319         case FS_IOC_GETVERSION:
 320         case FS_IOC_SETVERSION:
 321                 rc = lower_file->f_op->unlocked_ioctl(lower_file, cmd, arg);
 322                 fsstack_copy_attr_all(file_inode(file), file_inode(lower_file));
 323
 324                 return rc;
 325         default:
 326                 return rc;
 327         }
 328 }
 329
 330 #ifdef CONFIG_COMPAT
 331 static long
 332 ecryptfs_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 333 {
 334         struct file *lower_file = ecryptfs_file_to_lower(file);
 335         long rc = -ENOIOCTLCMD;
 336
 337         if (!lower_file->f_op->compat_ioctl)
 338                 return rc;
 339
 340         switch (cmd) {
 341         case FITRIM:
 342         case FS_IOC32_GETFLAGS:
 343         case FS_IOC32_SETFLAGS:
 344         case FS_IOC32_GETVERSION:
 345         case FS_IOC32_SETVERSION:
 346                 rc = lower_file->f_op->compat_ioctl(lower_file, cmd, arg);
 347                 fsstack_copy_attr_all(file_inode(file), file_inode(lower_file));
 348
 349                 return rc;
 350         default:
 351                 return rc;
 352         }
 353 }
 354 #endif
 355
 356 const struct file_operations ecryptfs_dir_fops = {
 357         .iterate = ecryptfs_readdir,
 358         .read = generic_read_dir,
 359         .unlocked_ioctl = ecryptfs_unlocked_ioctl,
 360 #ifdef CONFIG_COMPAT
 361         .compat_ioctl = ecryptfs_compat_ioctl,
 362 #endif
 363         .open = ecryptfs_open,
 364         .flush = ecryptfs_flush,
 365         .release = ecryptfs_release,
 366         .fsync = ecryptfs_fsync,
 367         .fasync = ecryptfs_fasync,
 368         .splice_read = generic_file_splice_read,
 369         .llseek = default_llseek,
 370 };
 371
 372 const struct file_operations ecryptfs_main_fops = {
 373         .llseek = generic_file_llseek,
 374         .read_iter = ecryptfs_read_update_atime,
 375         .write_iter = generic_file_write_iter,
 376         .iterate = ecryptfs_readdir,
 377         .unlocked_ioctl = ecryptfs_unlocked_ioctl,
 378 #ifdef CONFIG_COMPAT
 379         .compat_ioctl = ecryptfs_compat_ioctl,
 380 #endif
 381         .mmap = ecryptfs_mmap,
 382         .open = ecryptfs_open,
 383         .flush = ecryptfs_flush,
 384         .release = ecryptfs_release,
 385         .fsync = ecryptfs_fsync,
 386         .fasync = ecryptfs_fasync,
 387         .splice_read = generic_file_splice_read,
 388 };