blob: db184ef15d3d8c012ce4586d7abf276efbf6eb8a [file] [log] [blame]
Michael Halcrowda0102a2007-10-16 01:28:07 -07001/**
2 * eCryptfs: Linux filesystem encryption layer
3 *
4 * Copyright (C) 2007 International Business Machines Corp.
5 * Author(s): Michael A. Halcrow <mahalcro@us.ibm.com>
6 *
7 * This program is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU General Public License as
9 * published by the Free Software Foundation; either version 2 of the
10 * License, or (at your option) any later version.
11 *
12 * This program is distributed in the hope that it will be useful, but
13 * WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 * General Public License for more details.
16 *
17 * You should have received a copy of the GNU General Public License
18 * along with this program; if not, write to the Free Software
19 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
20 * 02111-1307, USA.
21 */
22
23#include <linux/fs.h>
24#include <linux/pagemap.h>
25#include "ecryptfs_kernel.h"
26
27/**
28 * ecryptfs_write_lower
29 * @ecryptfs_inode: The eCryptfs inode
30 * @data: Data to write
31 * @offset: Byte offset in the lower file to which to write the data
32 * @size: Number of bytes from @data to write at @offset in the lower
33 * file
34 *
35 * Write data to the lower file.
36 *
Tyler Hicks96a7b9c2009-09-16 19:04:20 -050037 * Returns bytes written on success; less than zero on error
Michael Halcrowda0102a2007-10-16 01:28:07 -070038 */
39int ecryptfs_write_lower(struct inode *ecryptfs_inode, char *data,
40 loff_t offset, size_t size)
41{
42 struct ecryptfs_inode_info *inode_info;
Michael Halcrowda0102a2007-10-16 01:28:07 -070043 mm_segment_t fs_save;
Tyler Hicks96a7b9c2009-09-16 19:04:20 -050044 ssize_t rc;
Michael Halcrowda0102a2007-10-16 01:28:07 -070045
46 inode_info = ecryptfs_inode_to_private(ecryptfs_inode);
47 mutex_lock(&inode_info->lower_file_mutex);
48 BUG_ON(!inode_info->lower_file);
49 inode_info->lower_file->f_pos = offset;
50 fs_save = get_fs();
51 set_fs(get_ds());
Tyler Hicks96a7b9c2009-09-16 19:04:20 -050052 rc = vfs_write(inode_info->lower_file, data, size,
53 &inode_info->lower_file->f_pos);
Michael Halcrowda0102a2007-10-16 01:28:07 -070054 set_fs(fs_save);
Michael Halcrowda0102a2007-10-16 01:28:07 -070055 mutex_unlock(&inode_info->lower_file_mutex);
56 mark_inode_dirty_sync(ecryptfs_inode);
57 return rc;
58}
59
60/**
61 * ecryptfs_write_lower_page_segment
62 * @ecryptfs_inode: The eCryptfs inode
63 * @page_for_lower: The page containing the data to be written to the
64 * lower file
65 * @offset_in_page: The offset in the @page_for_lower from which to
66 * start writing the data
67 * @size: The amount of data from @page_for_lower to write to the
68 * lower file
69 *
70 * Determines the byte offset in the file for the given page and
71 * offset within the page, maps the page, and makes the call to write
72 * the contents of @page_for_lower to the lower inode.
73 *
74 * Returns zero on success; non-zero otherwise
75 */
76int ecryptfs_write_lower_page_segment(struct inode *ecryptfs_inode,
77 struct page *page_for_lower,
78 size_t offset_in_page, size_t size)
79{
80 char *virt;
81 loff_t offset;
82 int rc;
83
Michael Halcrow8a146a22007-11-14 16:58:27 -080084 offset = ((((loff_t)page_for_lower->index) << PAGE_CACHE_SHIFT)
Michael Halcrowd6a13c12007-10-16 01:28:12 -070085 + offset_in_page);
Michael Halcrowda0102a2007-10-16 01:28:07 -070086 virt = kmap(page_for_lower);
87 rc = ecryptfs_write_lower(ecryptfs_inode, virt, offset, size);
Tyler Hicks96a7b9c2009-09-16 19:04:20 -050088 if (rc > 0)
89 rc = 0;
Michael Halcrowda0102a2007-10-16 01:28:07 -070090 kunmap(page_for_lower);
91 return rc;
92}
93
94/**
95 * ecryptfs_write
Al Viro48c1e442010-05-21 11:09:58 -040096 * @ecryptfs_inode: The eCryptfs file into which to write
Michael Halcrowda0102a2007-10-16 01:28:07 -070097 * @data: Virtual address where data to write is located
98 * @offset: Offset in the eCryptfs file at which to begin writing the
99 * data from @data
100 * @size: The number of bytes to write from @data
101 *
102 * Write an arbitrary amount of data to an arbitrary location in the
103 * eCryptfs inode page cache. This is done on a page-by-page, and then
104 * by an extent-by-extent, basis; individual extents are encrypted and
105 * written to the lower page cache (via VFS writes). This function
106 * takes care of all the address translation to locations in the lower
107 * filesystem; it also handles truncate events, writing out zeros
108 * where necessary.
109 *
110 * Returns zero on success; non-zero otherwise
111 */
Al Viro48c1e442010-05-21 11:09:58 -0400112int ecryptfs_write(struct inode *ecryptfs_inode, char *data, loff_t offset,
Michael Halcrowda0102a2007-10-16 01:28:07 -0700113 size_t size)
114{
115 struct page *ecryptfs_page;
Tyler Hicks13a791b2009-04-13 15:29:27 -0500116 struct ecryptfs_crypt_stat *crypt_stat;
Michael Halcrowda0102a2007-10-16 01:28:07 -0700117 char *ecryptfs_page_virt;
Tyler Hicks13a791b2009-04-13 15:29:27 -0500118 loff_t ecryptfs_file_size = i_size_read(ecryptfs_inode);
Michael Halcrowda0102a2007-10-16 01:28:07 -0700119 loff_t data_offset = 0;
120 loff_t pos;
121 int rc = 0;
122
Tyler Hicks13a791b2009-04-13 15:29:27 -0500123 crypt_stat = &ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat;
Eric Sandeen7a3f5952007-12-17 16:20:10 -0800124 /*
125 * if we are writing beyond current size, then start pos
126 * at the current size - we'll fill in zeros from there.
127 */
Michael Halcrowda0102a2007-10-16 01:28:07 -0700128 if (offset > ecryptfs_file_size)
129 pos = ecryptfs_file_size;
130 else
131 pos = offset;
132 while (pos < (offset + size)) {
133 pgoff_t ecryptfs_page_idx = (pos >> PAGE_CACHE_SHIFT);
134 size_t start_offset_in_page = (pos & ~PAGE_CACHE_MASK);
135 size_t num_bytes = (PAGE_CACHE_SIZE - start_offset_in_page);
136 size_t total_remaining_bytes = ((offset + size) - pos);
137
138 if (num_bytes > total_remaining_bytes)
139 num_bytes = total_remaining_bytes;
140 if (pos < offset) {
Eric Sandeen7a3f5952007-12-17 16:20:10 -0800141 /* remaining zeros to write, up to destination offset */
Michael Halcrowda0102a2007-10-16 01:28:07 -0700142 size_t total_remaining_zeros = (offset - pos);
143
144 if (num_bytes > total_remaining_zeros)
145 num_bytes = total_remaining_zeros;
146 }
Al Viro02bd9792010-05-21 11:02:14 -0400147 ecryptfs_page = ecryptfs_get_locked_page(ecryptfs_inode,
Michael Halcrow16a72c42007-10-16 01:28:14 -0700148 ecryptfs_page_idx);
Michael Halcrowda0102a2007-10-16 01:28:07 -0700149 if (IS_ERR(ecryptfs_page)) {
150 rc = PTR_ERR(ecryptfs_page);
151 printk(KERN_ERR "%s: Error getting page at "
152 "index [%ld] from eCryptfs inode "
Harvey Harrison18d1dbf2008-04-29 00:59:48 -0700153 "mapping; rc = [%d]\n", __func__,
Michael Halcrowda0102a2007-10-16 01:28:07 -0700154 ecryptfs_page_idx, rc);
155 goto out;
156 }
Michael Halcrowda0102a2007-10-16 01:28:07 -0700157 ecryptfs_page_virt = kmap_atomic(ecryptfs_page, KM_USER0);
Eric Sandeen7a3f5952007-12-17 16:20:10 -0800158
159 /*
160 * pos: where we're now writing, offset: where the request was
161 * If current pos is before request, we are filling zeros
162 * If we are at or beyond request, we are writing the *data*
163 * If we're in a fresh page beyond eof, zero it in either case
164 */
165 if (pos < offset || !start_offset_in_page) {
166 /* We are extending past the previous end of the file.
167 * Fill in zero values to the end of the page */
168 memset(((char *)ecryptfs_page_virt
169 + start_offset_in_page), 0,
170 PAGE_CACHE_SIZE - start_offset_in_page);
171 }
172
173 /* pos >= offset, we are now writing the data request */
Michael Halcrowda0102a2007-10-16 01:28:07 -0700174 if (pos >= offset) {
175 memcpy(((char *)ecryptfs_page_virt
176 + start_offset_in_page),
177 (data + data_offset), num_bytes);
178 data_offset += num_bytes;
Michael Halcrowda0102a2007-10-16 01:28:07 -0700179 }
180 kunmap_atomic(ecryptfs_page_virt, KM_USER0);
181 flush_dcache_page(ecryptfs_page);
Michael Halcrow16a72c42007-10-16 01:28:14 -0700182 SetPageUptodate(ecryptfs_page);
183 unlock_page(ecryptfs_page);
Tyler Hicks13a791b2009-04-13 15:29:27 -0500184 if (crypt_stat->flags & ECRYPTFS_ENCRYPTED)
185 rc = ecryptfs_encrypt_page(ecryptfs_page);
186 else
187 rc = ecryptfs_write_lower_page_segment(ecryptfs_inode,
188 ecryptfs_page,
189 start_offset_in_page,
190 data_offset);
Michael Halcrow16a72c42007-10-16 01:28:14 -0700191 page_cache_release(ecryptfs_page);
Michael Halcrowda0102a2007-10-16 01:28:07 -0700192 if (rc) {
193 printk(KERN_ERR "%s: Error encrypting "
Harvey Harrison18d1dbf2008-04-29 00:59:48 -0700194 "page; rc = [%d]\n", __func__, rc);
Michael Halcrowda0102a2007-10-16 01:28:07 -0700195 goto out;
196 }
Michael Halcrowda0102a2007-10-16 01:28:07 -0700197 pos += num_bytes;
198 }
199 if ((offset + size) > ecryptfs_file_size) {
Tyler Hicks13a791b2009-04-13 15:29:27 -0500200 i_size_write(ecryptfs_inode, (offset + size));
201 if (crypt_stat->flags & ECRYPTFS_ENCRYPTED) {
202 rc = ecryptfs_write_inode_size_to_metadata(
203 ecryptfs_inode);
204 if (rc) {
205 printk(KERN_ERR "Problem with "
206 "ecryptfs_write_inode_size_to_metadata; "
207 "rc = [%d]\n", rc);
208 goto out;
209 }
Michael Halcrowda0102a2007-10-16 01:28:07 -0700210 }
211 }
212out:
213 return rc;
214}
215
216/**
217 * ecryptfs_read_lower
218 * @data: The read data is stored here by this function
219 * @offset: Byte offset in the lower file from which to read the data
220 * @size: Number of bytes to read from @offset of the lower file and
221 * store into @data
222 * @ecryptfs_inode: The eCryptfs inode
223 *
224 * Read @size bytes of data at byte offset @offset from the lower
225 * inode into memory location @data.
226 *
Tyler Hicks96a7b9c2009-09-16 19:04:20 -0500227 * Returns bytes read on success; 0 on EOF; less than zero on error
Michael Halcrowda0102a2007-10-16 01:28:07 -0700228 */
229int ecryptfs_read_lower(char *data, loff_t offset, size_t size,
230 struct inode *ecryptfs_inode)
231{
232 struct ecryptfs_inode_info *inode_info =
233 ecryptfs_inode_to_private(ecryptfs_inode);
Michael Halcrowda0102a2007-10-16 01:28:07 -0700234 mm_segment_t fs_save;
Tyler Hicks96a7b9c2009-09-16 19:04:20 -0500235 ssize_t rc;
Michael Halcrowda0102a2007-10-16 01:28:07 -0700236
237 mutex_lock(&inode_info->lower_file_mutex);
238 BUG_ON(!inode_info->lower_file);
239 inode_info->lower_file->f_pos = offset;
240 fs_save = get_fs();
241 set_fs(get_ds());
Tyler Hicks96a7b9c2009-09-16 19:04:20 -0500242 rc = vfs_read(inode_info->lower_file, data, size,
243 &inode_info->lower_file->f_pos);
Michael Halcrowda0102a2007-10-16 01:28:07 -0700244 set_fs(fs_save);
Michael Halcrowda0102a2007-10-16 01:28:07 -0700245 mutex_unlock(&inode_info->lower_file_mutex);
Michael Halcrowda0102a2007-10-16 01:28:07 -0700246 return rc;
247}
248
249/**
250 * ecryptfs_read_lower_page_segment
251 * @page_for_ecryptfs: The page into which data for eCryptfs will be
252 * written
253 * @offset_in_page: Offset in @page_for_ecryptfs from which to start
254 * writing
255 * @size: The number of bytes to write into @page_for_ecryptfs
256 * @ecryptfs_inode: The eCryptfs inode
257 *
258 * Determines the byte offset in the file for the given page and
259 * offset within the page, maps the page, and makes the call to read
260 * the contents of @page_for_ecryptfs from the lower inode.
261 *
262 * Returns zero on success; non-zero otherwise
263 */
264int ecryptfs_read_lower_page_segment(struct page *page_for_ecryptfs,
265 pgoff_t page_index,
266 size_t offset_in_page, size_t size,
267 struct inode *ecryptfs_inode)
268{
269 char *virt;
270 loff_t offset;
271 int rc;
272
Michael Halcrowd6a13c12007-10-16 01:28:12 -0700273 offset = ((((loff_t)page_index) << PAGE_CACHE_SHIFT) + offset_in_page);
Michael Halcrowda0102a2007-10-16 01:28:07 -0700274 virt = kmap(page_for_ecryptfs);
275 rc = ecryptfs_read_lower(virt, offset, size, ecryptfs_inode);
Tyler Hicks96a7b9c2009-09-16 19:04:20 -0500276 if (rc > 0)
277 rc = 0;
Michael Halcrowda0102a2007-10-16 01:28:07 -0700278 kunmap(page_for_ecryptfs);
Michael Halcrow16a72c42007-10-16 01:28:14 -0700279 flush_dcache_page(page_for_ecryptfs);
Michael Halcrowda0102a2007-10-16 01:28:07 -0700280 return rc;
281}
282
Adrian Bunk7896b632008-02-06 01:38:32 -0800283#if 0
Michael Halcrowda0102a2007-10-16 01:28:07 -0700284/**
285 * ecryptfs_read
286 * @data: The virtual address into which to write the data read (and
287 * possibly decrypted) from the lower file
288 * @offset: The offset in the decrypted view of the file from which to
289 * read into @data
290 * @size: The number of bytes to read into @data
291 * @ecryptfs_file: The eCryptfs file from which to read
292 *
293 * Read an arbitrary amount of data from an arbitrary location in the
294 * eCryptfs page cache. This is done on an extent-by-extent basis;
295 * individual extents are decrypted and read from the lower page
296 * cache (via VFS reads). This function takes care of all the
297 * address translation to locations in the lower filesystem.
298 *
299 * Returns zero on success; non-zero otherwise
300 */
301int ecryptfs_read(char *data, loff_t offset, size_t size,
302 struct file *ecryptfs_file)
303{
Al Viro02bd9792010-05-21 11:02:14 -0400304 struct inode *ecryptfs_inode = ecryptfs_file->f_dentry->d_inode;
Michael Halcrowda0102a2007-10-16 01:28:07 -0700305 struct page *ecryptfs_page;
306 char *ecryptfs_page_virt;
Al Viro02bd9792010-05-21 11:02:14 -0400307 loff_t ecryptfs_file_size = i_size_read(ecryptfs_inode);
Michael Halcrowda0102a2007-10-16 01:28:07 -0700308 loff_t data_offset = 0;
309 loff_t pos;
310 int rc = 0;
311
312 if ((offset + size) > ecryptfs_file_size) {
313 rc = -EINVAL;
314 printk(KERN_ERR "%s: Attempt to read data past the end of the "
315 "file; offset = [%lld]; size = [%td]; "
316 "ecryptfs_file_size = [%lld]\n",
Harvey Harrison18d1dbf2008-04-29 00:59:48 -0700317 __func__, offset, size, ecryptfs_file_size);
Michael Halcrowda0102a2007-10-16 01:28:07 -0700318 goto out;
319 }
320 pos = offset;
321 while (pos < (offset + size)) {
322 pgoff_t ecryptfs_page_idx = (pos >> PAGE_CACHE_SHIFT);
323 size_t start_offset_in_page = (pos & ~PAGE_CACHE_MASK);
324 size_t num_bytes = (PAGE_CACHE_SIZE - start_offset_in_page);
325 size_t total_remaining_bytes = ((offset + size) - pos);
326
327 if (num_bytes > total_remaining_bytes)
328 num_bytes = total_remaining_bytes;
Al Viro02bd9792010-05-21 11:02:14 -0400329 ecryptfs_page = ecryptfs_get_locked_page(ecryptfs_inode,
Michael Halcrow16a72c42007-10-16 01:28:14 -0700330 ecryptfs_page_idx);
Michael Halcrowda0102a2007-10-16 01:28:07 -0700331 if (IS_ERR(ecryptfs_page)) {
332 rc = PTR_ERR(ecryptfs_page);
333 printk(KERN_ERR "%s: Error getting page at "
334 "index [%ld] from eCryptfs inode "
Harvey Harrison18d1dbf2008-04-29 00:59:48 -0700335 "mapping; rc = [%d]\n", __func__,
Michael Halcrowda0102a2007-10-16 01:28:07 -0700336 ecryptfs_page_idx, rc);
337 goto out;
338 }
Michael Halcrowda0102a2007-10-16 01:28:07 -0700339 ecryptfs_page_virt = kmap_atomic(ecryptfs_page, KM_USER0);
340 memcpy((data + data_offset),
341 ((char *)ecryptfs_page_virt + start_offset_in_page),
342 num_bytes);
343 kunmap_atomic(ecryptfs_page_virt, KM_USER0);
Michael Halcrow16a72c42007-10-16 01:28:14 -0700344 flush_dcache_page(ecryptfs_page);
345 SetPageUptodate(ecryptfs_page);
346 unlock_page(ecryptfs_page);
Michael Halcrowda0102a2007-10-16 01:28:07 -0700347 page_cache_release(ecryptfs_page);
348 pos += num_bytes;
349 data_offset += num_bytes;
350 }
351out:
352 return rc;
353}
Adrian Bunk7896b632008-02-06 01:38:32 -0800354#endif /* 0 */