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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                                 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 };
438 

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