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TOMOYO Linux Cross Reference
Linux/fs/ecryptfs/file.c

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  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                                 const struct iovec *iov,
 48                                 unsigned long nr_segs, loff_t pos)
 49 {
 50         ssize_t rc;
 51         struct path lower;
 52         struct file *file = iocb->ki_filp;
 53 
 54         rc = generic_file_aio_read(iocb, iov, nr_segs, pos);
 55         /*
 56          * Even though this is a async interface, we need to wait
 57          * for IO to finish to update atime
 58          */
 59         if (-EIOCBQUEUED == rc)
 60                 rc = wait_on_sync_kiocb(iocb);
 61         if (rc >= 0) {
 62                 lower.dentry = ecryptfs_dentry_to_lower(file->f_path.dentry);
 63                 lower.mnt = ecryptfs_dentry_to_lower_mnt(file->f_path.dentry);
 64                 touch_atime(&lower);
 65         }
 66         return rc;
 67 }
 68 
 69 struct ecryptfs_getdents_callback {
 70         void *dirent;
 71         struct dentry *dentry;
 72         filldir_t filldir;
 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->dentry, 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         rc = buf->filldir(buf->dirent, name, name_size, offset, ino, d_type);
 99         kfree(name);
100         if (rc >= 0)
101                 buf->entries_written++;
102 out:
103         return rc;
104 }
105 
106 /**
107  * ecryptfs_readdir
108  * @file: The eCryptfs directory file
109  * @dirent: Directory entry handle
110  * @filldir: The filldir callback function
111  */
112 static int ecryptfs_readdir(struct file *file, void *dirent, filldir_t filldir)
113 {
114         int rc;
115         struct file *lower_file;
116         struct inode *inode;
117         struct ecryptfs_getdents_callback buf;
118 
119         lower_file = ecryptfs_file_to_lower(file);
120         lower_file->f_pos = file->f_pos;
121         inode = file->f_path.dentry->d_inode;
122         memset(&buf, 0, sizeof(buf));
123         buf.dirent = dirent;
124         buf.dentry = file->f_path.dentry;
125         buf.filldir = filldir;
126         buf.filldir_called = 0;
127         buf.entries_written = 0;
128         rc = vfs_readdir(lower_file, ecryptfs_filldir, (void *)&buf);
129         file->f_pos = lower_file->f_pos;
130         if (rc < 0)
131                 goto out;
132         if (buf.filldir_called && !buf.entries_written)
133                 goto out;
134         if (rc >= 0)
135                 fsstack_copy_attr_atime(inode,
136                                         lower_file->f_path.dentry->d_inode);
137 out:
138         return rc;
139 }
140 
141 struct kmem_cache *ecryptfs_file_info_cache;
142 
143 static int read_or_initialize_metadata(struct dentry *dentry)
144 {
145         struct inode *inode = dentry->d_inode;
146         struct ecryptfs_mount_crypt_stat *mount_crypt_stat;
147         struct ecryptfs_crypt_stat *crypt_stat;
148         int rc;
149 
150         crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat;
151         mount_crypt_stat = &ecryptfs_superblock_to_private(
152                                                 inode->i_sb)->mount_crypt_stat;
153         mutex_lock(&crypt_stat->cs_mutex);
154 
155         if (crypt_stat->flags & ECRYPTFS_POLICY_APPLIED &&
156             crypt_stat->flags & ECRYPTFS_KEY_VALID) {
157                 rc = 0;
158                 goto out;
159         }
160 
161         rc = ecryptfs_read_metadata(dentry);
162         if (!rc)
163                 goto out;
164 
165         if (mount_crypt_stat->flags & ECRYPTFS_PLAINTEXT_PASSTHROUGH_ENABLED) {
166                 crypt_stat->flags &= ~(ECRYPTFS_I_SIZE_INITIALIZED
167                                        | ECRYPTFS_ENCRYPTED);
168                 rc = 0;
169                 goto out;
170         }
171 
172         if (!(mount_crypt_stat->flags & ECRYPTFS_XATTR_METADATA_ENABLED) &&
173             !i_size_read(ecryptfs_inode_to_lower(inode))) {
174                 rc = ecryptfs_initialize_file(dentry, inode);
175                 if (!rc)
176                         goto out;
177         }
178 
179         rc = -EIO;
180 out:
181         mutex_unlock(&crypt_stat->cs_mutex);
182         return rc;
183 }
184 
185 /**
186  * ecryptfs_open
187  * @inode: inode speciying 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 dentry *lower_dentry;
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         lower_dentry = ecryptfs_dentry_to_lower(ecryptfs_dentry);
214         crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat;
215         mutex_lock(&crypt_stat->cs_mutex);
216         if (!(crypt_stat->flags & ECRYPTFS_POLICY_APPLIED)) {
217                 ecryptfs_printk(KERN_DEBUG, "Setting flags for stat...\n");
218                 /* Policy code enabled in future release */
219                 crypt_stat->flags |= (ECRYPTFS_POLICY_APPLIED
220                                       | ECRYPTFS_ENCRYPTED);
221         }
222         mutex_unlock(&crypt_stat->cs_mutex);
223         rc = ecryptfs_get_lower_file(ecryptfs_dentry, inode);
224         if (rc) {
225                 printk(KERN_ERR "%s: Error attempting to initialize "
226                         "the lower file for the dentry with name "
227                         "[%s]; rc = [%d]\n", __func__,
228                         ecryptfs_dentry->d_name.name, rc);
229                 goto out_free;
230         }
231         if ((ecryptfs_inode_to_private(inode)->lower_file->f_flags & O_ACCMODE)
232             == O_RDONLY && (file->f_flags & O_ACCMODE) != O_RDONLY) {
233                 rc = -EPERM;
234                 printk(KERN_WARNING "%s: Lower file is RO; eCryptfs "
235                        "file must hence be opened RO\n", __func__);
236                 goto out_put;
237         }
238         ecryptfs_set_file_lower(
239                 file, ecryptfs_inode_to_private(inode)->lower_file);
240         if (S_ISDIR(ecryptfs_dentry->d_inode->i_mode)) {
241                 ecryptfs_printk(KERN_DEBUG, "This is a directory\n");
242                 mutex_lock(&crypt_stat->cs_mutex);
243                 crypt_stat->flags &= ~(ECRYPTFS_ENCRYPTED);
244                 mutex_unlock(&crypt_stat->cs_mutex);
245                 rc = 0;
246                 goto out;
247         }
248         rc = read_or_initialize_metadata(ecryptfs_dentry);
249         if (rc)
250                 goto out_put;
251         ecryptfs_printk(KERN_DEBUG, "inode w/ addr = [0x%p], i_ino = "
252                         "[0x%.16lx] size: [0x%.16llx]\n", inode, inode->i_ino,
253                         (unsigned long long)i_size_read(inode));
254         goto out;
255 out_put:
256         ecryptfs_put_lower_file(inode);
257 out_free:
258         kmem_cache_free(ecryptfs_file_info_cache,
259                         ecryptfs_file_to_private(file));
260 out:
261         return rc;
262 }
263 
264 static int ecryptfs_flush(struct file *file, fl_owner_t td)
265 {
266         struct file *lower_file = ecryptfs_file_to_lower(file);
267 
268         if (lower_file->f_op && lower_file->f_op->flush) {
269                 filemap_write_and_wait(file->f_mapping);
270                 return lower_file->f_op->flush(lower_file, td);
271         }
272 
273         return 0;
274 }
275 
276 static int ecryptfs_release(struct inode *inode, struct file *file)
277 {
278         ecryptfs_put_lower_file(inode);
279         kmem_cache_free(ecryptfs_file_info_cache,
280                         ecryptfs_file_to_private(file));
281         return 0;
282 }
283 
284 static int
285 ecryptfs_fsync(struct file *file, loff_t start, loff_t end, int datasync)
286 {
287         return vfs_fsync(ecryptfs_file_to_lower(file), datasync);
288 }
289 
290 static int ecryptfs_fasync(int fd, struct file *file, int flag)
291 {
292         int rc = 0;
293         struct file *lower_file = NULL;
294 
295         lower_file = ecryptfs_file_to_lower(file);
296         if (lower_file->f_op && lower_file->f_op->fasync)
297                 rc = lower_file->f_op->fasync(fd, lower_file, flag);
298         return rc;
299 }
300 
301 static long
302 ecryptfs_unlocked_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
303 {
304         struct file *lower_file = NULL;
305         long rc = -ENOTTY;
306 
307         if (ecryptfs_file_to_private(file))
308                 lower_file = ecryptfs_file_to_lower(file);
309         if (!(lower_file && lower_file->f_op && lower_file->f_op->unlocked_ioctl))
310                 return rc;
311 
312         switch (cmd) {
313         case FITRIM:
314         case FS_IOC_GETFLAGS:
315         case FS_IOC_SETFLAGS:
316         case FS_IOC_GETVERSION:
317         case FS_IOC_SETVERSION:
318                 rc = lower_file->f_op->unlocked_ioctl(lower_file, cmd, arg);
319                 fsstack_copy_attr_all(file->f_path.dentry->d_inode,
320                                       lower_file->f_path.dentry->d_inode);
321                 return rc;
322         default:
323                 return rc;
324         }
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                 return rc;
338 
339         switch (cmd) {
340         case FITRIM:
341         case FS_IOC32_GETFLAGS:
342         case FS_IOC32_SETFLAGS:
343         case FS_IOC32_GETVERSION:
344         case FS_IOC32_SETVERSION:
345                 rc = lower_file->f_op->compat_ioctl(lower_file, cmd, arg);
346                 fsstack_copy_attr_all(file->f_path.dentry->d_inode,
347                                       lower_file->f_path.dentry->d_inode);
348                 return rc;
349         default:
350                 return rc;
351         }
352 }
353 #endif
354 
355 const struct file_operations ecryptfs_dir_fops = {
356         .readdir = ecryptfs_readdir,
357         .read = generic_read_dir,
358         .unlocked_ioctl = ecryptfs_unlocked_ioctl,
359 #ifdef CONFIG_COMPAT
360         .compat_ioctl = ecryptfs_compat_ioctl,
361 #endif
362         .open = ecryptfs_open,
363         .flush = ecryptfs_flush,
364         .release = ecryptfs_release,
365         .fsync = ecryptfs_fsync,
366         .fasync = ecryptfs_fasync,
367         .splice_read = generic_file_splice_read,
368         .llseek = default_llseek,
369 };
370 
371 const struct file_operations ecryptfs_main_fops = {
372         .llseek = generic_file_llseek,
373         .read = do_sync_read,
374         .aio_read = ecryptfs_read_update_atime,
375         .write = do_sync_write,
376         .aio_write = generic_file_aio_write,
377         .readdir = ecryptfs_readdir,
378         .unlocked_ioctl = ecryptfs_unlocked_ioctl,
379 #ifdef CONFIG_COMPAT
380         .compat_ioctl = ecryptfs_compat_ioctl,
381 #endif
382         .mmap = generic_file_mmap,
383         .open = ecryptfs_open,
384         .flush = ecryptfs_flush,
385         .release = ecryptfs_release,
386         .fsync = ecryptfs_fsync,
387         .fasync = ecryptfs_fasync,
388         .splice_read = generic_file_splice_read,
389 };
390 

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