blob: 948f57624c05dd2bb1750ff05628f7931f44f2b7 [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 *
37 * Returns zero on success; non-zero on error
38 */
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;
43 ssize_t octets_written;
44 mm_segment_t fs_save;
45 int rc = 0;
46
47 inode_info = ecryptfs_inode_to_private(ecryptfs_inode);
48 mutex_lock(&inode_info->lower_file_mutex);
49 BUG_ON(!inode_info->lower_file);
50 inode_info->lower_file->f_pos = offset;
51 fs_save = get_fs();
52 set_fs(get_ds());
53 octets_written = vfs_write(inode_info->lower_file, data, size,
54 &inode_info->lower_file->f_pos);
55 set_fs(fs_save);
56 if (octets_written < 0) {
57 printk(KERN_ERR "%s: octets_written = [%td]; "
58 "expected [%td]\n", __FUNCTION__, octets_written, size);
59 rc = -EINVAL;
60 }
61 mutex_unlock(&inode_info->lower_file_mutex);
62 mark_inode_dirty_sync(ecryptfs_inode);
63 return rc;
64}
65
66/**
67 * ecryptfs_write_lower_page_segment
68 * @ecryptfs_inode: The eCryptfs inode
69 * @page_for_lower: The page containing the data to be written to the
70 * lower file
71 * @offset_in_page: The offset in the @page_for_lower from which to
72 * start writing the data
73 * @size: The amount of data from @page_for_lower to write to the
74 * lower file
75 *
76 * Determines the byte offset in the file for the given page and
77 * offset within the page, maps the page, and makes the call to write
78 * the contents of @page_for_lower to the lower inode.
79 *
80 * Returns zero on success; non-zero otherwise
81 */
82int ecryptfs_write_lower_page_segment(struct inode *ecryptfs_inode,
83 struct page *page_for_lower,
84 size_t offset_in_page, size_t size)
85{
86 char *virt;
87 loff_t offset;
88 int rc;
89
Michael Halcrow8a146a22007-11-14 16:58:27 -080090 offset = ((((loff_t)page_for_lower->index) << PAGE_CACHE_SHIFT)
Michael Halcrowd6a13c12007-10-16 01:28:12 -070091 + offset_in_page);
Michael Halcrowda0102a2007-10-16 01:28:07 -070092 virt = kmap(page_for_lower);
93 rc = ecryptfs_write_lower(ecryptfs_inode, virt, offset, size);
94 kunmap(page_for_lower);
95 return rc;
96}
97
98/**
99 * ecryptfs_write
100 * @ecryptfs_file: The eCryptfs file into which to write
101 * @data: Virtual address where data to write is located
102 * @offset: Offset in the eCryptfs file at which to begin writing the
103 * data from @data
104 * @size: The number of bytes to write from @data
105 *
106 * Write an arbitrary amount of data to an arbitrary location in the
107 * eCryptfs inode page cache. This is done on a page-by-page, and then
108 * by an extent-by-extent, basis; individual extents are encrypted and
109 * written to the lower page cache (via VFS writes). This function
110 * takes care of all the address translation to locations in the lower
111 * filesystem; it also handles truncate events, writing out zeros
112 * where necessary.
113 *
114 * Returns zero on success; non-zero otherwise
115 */
116int ecryptfs_write(struct file *ecryptfs_file, char *data, loff_t offset,
117 size_t size)
118{
119 struct page *ecryptfs_page;
120 char *ecryptfs_page_virt;
Michael Halcrowd6a13c12007-10-16 01:28:12 -0700121 loff_t ecryptfs_file_size =
122 i_size_read(ecryptfs_file->f_dentry->d_inode);
Michael Halcrowda0102a2007-10-16 01:28:07 -0700123 loff_t data_offset = 0;
124 loff_t pos;
125 int rc = 0;
126
Eric Sandeen7a3f5952007-12-17 16:20:10 -0800127 /*
128 * if we are writing beyond current size, then start pos
129 * at the current size - we'll fill in zeros from there.
130 */
Michael Halcrowda0102a2007-10-16 01:28:07 -0700131 if (offset > ecryptfs_file_size)
132 pos = ecryptfs_file_size;
133 else
134 pos = offset;
135 while (pos < (offset + size)) {
136 pgoff_t ecryptfs_page_idx = (pos >> PAGE_CACHE_SHIFT);
137 size_t start_offset_in_page = (pos & ~PAGE_CACHE_MASK);
138 size_t num_bytes = (PAGE_CACHE_SIZE - start_offset_in_page);
139 size_t total_remaining_bytes = ((offset + size) - pos);
140
141 if (num_bytes > total_remaining_bytes)
142 num_bytes = total_remaining_bytes;
143 if (pos < offset) {
Eric Sandeen7a3f5952007-12-17 16:20:10 -0800144 /* remaining zeros to write, up to destination offset */
Michael Halcrowda0102a2007-10-16 01:28:07 -0700145 size_t total_remaining_zeros = (offset - pos);
146
147 if (num_bytes > total_remaining_zeros)
148 num_bytes = total_remaining_zeros;
149 }
Michael Halcrow16a72c42007-10-16 01:28:14 -0700150 ecryptfs_page = ecryptfs_get_locked_page(ecryptfs_file,
151 ecryptfs_page_idx);
Michael Halcrowda0102a2007-10-16 01:28:07 -0700152 if (IS_ERR(ecryptfs_page)) {
153 rc = PTR_ERR(ecryptfs_page);
154 printk(KERN_ERR "%s: Error getting page at "
155 "index [%ld] from eCryptfs inode "
156 "mapping; rc = [%d]\n", __FUNCTION__,
157 ecryptfs_page_idx, rc);
158 goto out;
159 }
160 if (start_offset_in_page) {
161 /* Read in the page from the lower
162 * into the eCryptfs inode page cache,
163 * decrypting */
Michael Halcrow0216f7f2007-10-16 01:28:08 -0700164 rc = ecryptfs_decrypt_page(ecryptfs_page);
165 if (rc) {
Michael Halcrowda0102a2007-10-16 01:28:07 -0700166 printk(KERN_ERR "%s: Error decrypting "
167 "page; rc = [%d]\n",
168 __FUNCTION__, rc);
Michael Halcrow16a72c42007-10-16 01:28:14 -0700169 ClearPageUptodate(ecryptfs_page);
Michael Halcrowda0102a2007-10-16 01:28:07 -0700170 page_cache_release(ecryptfs_page);
171 goto out;
172 }
173 }
174 ecryptfs_page_virt = kmap_atomic(ecryptfs_page, KM_USER0);
Eric Sandeen7a3f5952007-12-17 16:20:10 -0800175
176 /*
177 * pos: where we're now writing, offset: where the request was
178 * If current pos is before request, we are filling zeros
179 * If we are at or beyond request, we are writing the *data*
180 * If we're in a fresh page beyond eof, zero it in either case
181 */
182 if (pos < offset || !start_offset_in_page) {
183 /* We are extending past the previous end of the file.
184 * Fill in zero values to the end of the page */
185 memset(((char *)ecryptfs_page_virt
186 + start_offset_in_page), 0,
187 PAGE_CACHE_SIZE - start_offset_in_page);
188 }
189
190 /* pos >= offset, we are now writing the data request */
Michael Halcrowda0102a2007-10-16 01:28:07 -0700191 if (pos >= offset) {
192 memcpy(((char *)ecryptfs_page_virt
193 + start_offset_in_page),
194 (data + data_offset), num_bytes);
195 data_offset += num_bytes;
Michael Halcrowda0102a2007-10-16 01:28:07 -0700196 }
197 kunmap_atomic(ecryptfs_page_virt, KM_USER0);
198 flush_dcache_page(ecryptfs_page);
Michael Halcrow16a72c42007-10-16 01:28:14 -0700199 SetPageUptodate(ecryptfs_page);
200 unlock_page(ecryptfs_page);
Michael Halcrow0216f7f2007-10-16 01:28:08 -0700201 rc = ecryptfs_encrypt_page(ecryptfs_page);
Michael Halcrow16a72c42007-10-16 01:28:14 -0700202 page_cache_release(ecryptfs_page);
Michael Halcrowda0102a2007-10-16 01:28:07 -0700203 if (rc) {
204 printk(KERN_ERR "%s: Error encrypting "
205 "page; rc = [%d]\n", __FUNCTION__, rc);
Michael Halcrowda0102a2007-10-16 01:28:07 -0700206 goto out;
207 }
Michael Halcrowda0102a2007-10-16 01:28:07 -0700208 pos += num_bytes;
209 }
210 if ((offset + size) > ecryptfs_file_size) {
211 i_size_write(ecryptfs_file->f_dentry->d_inode, (offset + size));
Michael Halcrow0216f7f2007-10-16 01:28:08 -0700212 rc = ecryptfs_write_inode_size_to_metadata(
213 ecryptfs_file->f_dentry->d_inode);
Michael Halcrowda0102a2007-10-16 01:28:07 -0700214 if (rc) {
215 printk(KERN_ERR "Problem with "
216 "ecryptfs_write_inode_size_to_metadata; "
217 "rc = [%d]\n", rc);
218 goto out;
219 }
220 }
221out:
222 return rc;
223}
224
225/**
226 * ecryptfs_read_lower
227 * @data: The read data is stored here by this function
228 * @offset: Byte offset in the lower file from which to read the data
229 * @size: Number of bytes to read from @offset of the lower file and
230 * store into @data
231 * @ecryptfs_inode: The eCryptfs inode
232 *
233 * Read @size bytes of data at byte offset @offset from the lower
234 * inode into memory location @data.
235 *
236 * Returns zero on success; non-zero on error
237 */
238int ecryptfs_read_lower(char *data, loff_t offset, size_t size,
239 struct inode *ecryptfs_inode)
240{
241 struct ecryptfs_inode_info *inode_info =
242 ecryptfs_inode_to_private(ecryptfs_inode);
243 ssize_t octets_read;
244 mm_segment_t fs_save;
Michael Halcrowda0102a2007-10-16 01:28:07 -0700245 int rc = 0;
246
247 mutex_lock(&inode_info->lower_file_mutex);
248 BUG_ON(!inode_info->lower_file);
249 inode_info->lower_file->f_pos = offset;
250 fs_save = get_fs();
251 set_fs(get_ds());
252 octets_read = vfs_read(inode_info->lower_file, data, size,
253 &inode_info->lower_file->f_pos);
254 set_fs(fs_save);
255 if (octets_read < 0) {
256 printk(KERN_ERR "%s: octets_read = [%td]; "
257 "expected [%td]\n", __FUNCTION__, octets_read, size);
258 rc = -EINVAL;
259 }
260 mutex_unlock(&inode_info->lower_file_mutex);
Michael Halcrowda0102a2007-10-16 01:28:07 -0700261 return rc;
262}
263
264/**
265 * ecryptfs_read_lower_page_segment
266 * @page_for_ecryptfs: The page into which data for eCryptfs will be
267 * written
268 * @offset_in_page: Offset in @page_for_ecryptfs from which to start
269 * writing
270 * @size: The number of bytes to write into @page_for_ecryptfs
271 * @ecryptfs_inode: The eCryptfs inode
272 *
273 * Determines the byte offset in the file for the given page and
274 * offset within the page, maps the page, and makes the call to read
275 * the contents of @page_for_ecryptfs from the lower inode.
276 *
277 * Returns zero on success; non-zero otherwise
278 */
279int ecryptfs_read_lower_page_segment(struct page *page_for_ecryptfs,
280 pgoff_t page_index,
281 size_t offset_in_page, size_t size,
282 struct inode *ecryptfs_inode)
283{
284 char *virt;
285 loff_t offset;
286 int rc;
287
Michael Halcrowd6a13c12007-10-16 01:28:12 -0700288 offset = ((((loff_t)page_index) << PAGE_CACHE_SHIFT) + offset_in_page);
Michael Halcrowda0102a2007-10-16 01:28:07 -0700289 virt = kmap(page_for_ecryptfs);
290 rc = ecryptfs_read_lower(virt, offset, size, ecryptfs_inode);
291 kunmap(page_for_ecryptfs);
Michael Halcrow16a72c42007-10-16 01:28:14 -0700292 flush_dcache_page(page_for_ecryptfs);
Michael Halcrowda0102a2007-10-16 01:28:07 -0700293 return rc;
294}
295
296/**
297 * ecryptfs_read
298 * @data: The virtual address into which to write the data read (and
299 * possibly decrypted) from the lower file
300 * @offset: The offset in the decrypted view of the file from which to
301 * read into @data
302 * @size: The number of bytes to read into @data
303 * @ecryptfs_file: The eCryptfs file from which to read
304 *
305 * Read an arbitrary amount of data from an arbitrary location in the
306 * eCryptfs page cache. This is done on an extent-by-extent basis;
307 * individual extents are decrypted and read from the lower page
308 * cache (via VFS reads). This function takes care of all the
309 * address translation to locations in the lower filesystem.
310 *
311 * Returns zero on success; non-zero otherwise
312 */
313int ecryptfs_read(char *data, loff_t offset, size_t size,
314 struct file *ecryptfs_file)
315{
316 struct page *ecryptfs_page;
317 char *ecryptfs_page_virt;
Michael Halcrowd6a13c12007-10-16 01:28:12 -0700318 loff_t ecryptfs_file_size =
319 i_size_read(ecryptfs_file->f_dentry->d_inode);
Michael Halcrowda0102a2007-10-16 01:28:07 -0700320 loff_t data_offset = 0;
321 loff_t pos;
322 int rc = 0;
323
324 if ((offset + size) > ecryptfs_file_size) {
325 rc = -EINVAL;
326 printk(KERN_ERR "%s: Attempt to read data past the end of the "
327 "file; offset = [%lld]; size = [%td]; "
328 "ecryptfs_file_size = [%lld]\n",
329 __FUNCTION__, offset, size, ecryptfs_file_size);
330 goto out;
331 }
332 pos = offset;
333 while (pos < (offset + size)) {
334 pgoff_t ecryptfs_page_idx = (pos >> PAGE_CACHE_SHIFT);
335 size_t start_offset_in_page = (pos & ~PAGE_CACHE_MASK);
336 size_t num_bytes = (PAGE_CACHE_SIZE - start_offset_in_page);
337 size_t total_remaining_bytes = ((offset + size) - pos);
338
339 if (num_bytes > total_remaining_bytes)
340 num_bytes = total_remaining_bytes;
Michael Halcrow16a72c42007-10-16 01:28:14 -0700341 ecryptfs_page = ecryptfs_get_locked_page(ecryptfs_file,
342 ecryptfs_page_idx);
Michael Halcrowda0102a2007-10-16 01:28:07 -0700343 if (IS_ERR(ecryptfs_page)) {
344 rc = PTR_ERR(ecryptfs_page);
345 printk(KERN_ERR "%s: Error getting page at "
346 "index [%ld] from eCryptfs inode "
347 "mapping; rc = [%d]\n", __FUNCTION__,
348 ecryptfs_page_idx, rc);
349 goto out;
350 }
Michael Halcrow0216f7f2007-10-16 01:28:08 -0700351 rc = ecryptfs_decrypt_page(ecryptfs_page);
Michael Halcrowda0102a2007-10-16 01:28:07 -0700352 if (rc) {
353 printk(KERN_ERR "%s: Error decrypting "
354 "page; rc = [%d]\n", __FUNCTION__, rc);
Michael Halcrow16a72c42007-10-16 01:28:14 -0700355 ClearPageUptodate(ecryptfs_page);
Michael Halcrowda0102a2007-10-16 01:28:07 -0700356 page_cache_release(ecryptfs_page);
357 goto out;
358 }
359 ecryptfs_page_virt = kmap_atomic(ecryptfs_page, KM_USER0);
360 memcpy((data + data_offset),
361 ((char *)ecryptfs_page_virt + start_offset_in_page),
362 num_bytes);
363 kunmap_atomic(ecryptfs_page_virt, KM_USER0);
Michael Halcrow16a72c42007-10-16 01:28:14 -0700364 flush_dcache_page(ecryptfs_page);
365 SetPageUptodate(ecryptfs_page);
366 unlock_page(ecryptfs_page);
Michael Halcrowda0102a2007-10-16 01:28:07 -0700367 page_cache_release(ecryptfs_page);
368 pos += num_bytes;
369 data_offset += num_bytes;
370 }
371out:
372 return rc;
373}