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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
96 * @ecryptfs_file: The eCryptfs file into which to write
97 * @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 */
112int ecryptfs_write(struct file *ecryptfs_file, char *data, loff_t offset,
113 size_t size)
114{
115 struct page *ecryptfs_page;
Tyler Hicks13a791b2009-04-13 15:29:27 -0500116 struct ecryptfs_crypt_stat *crypt_stat;
117 struct inode *ecryptfs_inode = ecryptfs_file->f_dentry->d_inode;
Michael Halcrowda0102a2007-10-16 01:28:07 -0700118 char *ecryptfs_page_virt;
Tyler Hicks13a791b2009-04-13 15:29:27 -0500119 loff_t ecryptfs_file_size = i_size_read(ecryptfs_inode);
Michael Halcrowda0102a2007-10-16 01:28:07 -0700120 loff_t data_offset = 0;
121 loff_t pos;
122 int rc = 0;
123
Tyler Hicks13a791b2009-04-13 15:29:27 -0500124 crypt_stat = &ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat;
Eric Sandeen7a3f5952007-12-17 16:20:10 -0800125 /*
126 * if we are writing beyond current size, then start pos
127 * at the current size - we'll fill in zeros from there.
128 */
Michael Halcrowda0102a2007-10-16 01:28:07 -0700129 if (offset > ecryptfs_file_size)
130 pos = ecryptfs_file_size;
131 else
132 pos = offset;
133 while (pos < (offset + size)) {
134 pgoff_t ecryptfs_page_idx = (pos >> PAGE_CACHE_SHIFT);
135 size_t start_offset_in_page = (pos & ~PAGE_CACHE_MASK);
136 size_t num_bytes = (PAGE_CACHE_SIZE - start_offset_in_page);
137 size_t total_remaining_bytes = ((offset + size) - pos);
138
139 if (num_bytes > total_remaining_bytes)
140 num_bytes = total_remaining_bytes;
141 if (pos < offset) {
Eric Sandeen7a3f5952007-12-17 16:20:10 -0800142 /* remaining zeros to write, up to destination offset */
Michael Halcrowda0102a2007-10-16 01:28:07 -0700143 size_t total_remaining_zeros = (offset - pos);
144
145 if (num_bytes > total_remaining_zeros)
146 num_bytes = total_remaining_zeros;
147 }
Michael Halcrow16a72c42007-10-16 01:28:14 -0700148 ecryptfs_page = ecryptfs_get_locked_page(ecryptfs_file,
149 ecryptfs_page_idx);
Michael Halcrowda0102a2007-10-16 01:28:07 -0700150 if (IS_ERR(ecryptfs_page)) {
151 rc = PTR_ERR(ecryptfs_page);
152 printk(KERN_ERR "%s: Error getting page at "
153 "index [%ld] from eCryptfs inode "
Harvey Harrison18d1dbf2008-04-29 00:59:48 -0700154 "mapping; rc = [%d]\n", __func__,
Michael Halcrowda0102a2007-10-16 01:28:07 -0700155 ecryptfs_page_idx, rc);
156 goto out;
157 }
Michael Halcrowda0102a2007-10-16 01:28:07 -0700158 ecryptfs_page_virt = kmap_atomic(ecryptfs_page, KM_USER0);
Eric Sandeen7a3f5952007-12-17 16:20:10 -0800159
160 /*
161 * pos: where we're now writing, offset: where the request was
162 * If current pos is before request, we are filling zeros
163 * If we are at or beyond request, we are writing the *data*
164 * If we're in a fresh page beyond eof, zero it in either case
165 */
166 if (pos < offset || !start_offset_in_page) {
167 /* We are extending past the previous end of the file.
168 * Fill in zero values to the end of the page */
169 memset(((char *)ecryptfs_page_virt
170 + start_offset_in_page), 0,
171 PAGE_CACHE_SIZE - start_offset_in_page);
172 }
173
174 /* pos >= offset, we are now writing the data request */
Michael Halcrowda0102a2007-10-16 01:28:07 -0700175 if (pos >= offset) {
176 memcpy(((char *)ecryptfs_page_virt
177 + start_offset_in_page),
178 (data + data_offset), num_bytes);
179 data_offset += num_bytes;
Michael Halcrowda0102a2007-10-16 01:28:07 -0700180 }
181 kunmap_atomic(ecryptfs_page_virt, KM_USER0);
182 flush_dcache_page(ecryptfs_page);
Michael Halcrow16a72c42007-10-16 01:28:14 -0700183 SetPageUptodate(ecryptfs_page);
184 unlock_page(ecryptfs_page);
Tyler Hicks13a791b2009-04-13 15:29:27 -0500185 if (crypt_stat->flags & ECRYPTFS_ENCRYPTED)
186 rc = ecryptfs_encrypt_page(ecryptfs_page);
187 else
188 rc = ecryptfs_write_lower_page_segment(ecryptfs_inode,
189 ecryptfs_page,
190 start_offset_in_page,
191 data_offset);
Michael Halcrow16a72c42007-10-16 01:28:14 -0700192 page_cache_release(ecryptfs_page);
Michael Halcrowda0102a2007-10-16 01:28:07 -0700193 if (rc) {
194 printk(KERN_ERR "%s: Error encrypting "
Harvey Harrison18d1dbf2008-04-29 00:59:48 -0700195 "page; rc = [%d]\n", __func__, rc);
Michael Halcrowda0102a2007-10-16 01:28:07 -0700196 goto out;
197 }
Michael Halcrowda0102a2007-10-16 01:28:07 -0700198 pos += num_bytes;
199 }
200 if ((offset + size) > ecryptfs_file_size) {
Tyler Hicks13a791b2009-04-13 15:29:27 -0500201 i_size_write(ecryptfs_inode, (offset + size));
202 if (crypt_stat->flags & ECRYPTFS_ENCRYPTED) {
203 rc = ecryptfs_write_inode_size_to_metadata(
204 ecryptfs_inode);
205 if (rc) {
206 printk(KERN_ERR "Problem with "
207 "ecryptfs_write_inode_size_to_metadata; "
208 "rc = [%d]\n", rc);
209 goto out;
210 }
Michael Halcrowda0102a2007-10-16 01:28:07 -0700211 }
212 }
213out:
214 return rc;
215}
216
217/**
218 * ecryptfs_read_lower
219 * @data: The read data is stored here by this function
220 * @offset: Byte offset in the lower file from which to read the data
221 * @size: Number of bytes to read from @offset of the lower file and
222 * store into @data
223 * @ecryptfs_inode: The eCryptfs inode
224 *
225 * Read @size bytes of data at byte offset @offset from the lower
226 * inode into memory location @data.
227 *
Tyler Hicks96a7b9c2009-09-16 19:04:20 -0500228 * Returns bytes read on success; 0 on EOF; less than zero on error
Michael Halcrowda0102a2007-10-16 01:28:07 -0700229 */
230int ecryptfs_read_lower(char *data, loff_t offset, size_t size,
231 struct inode *ecryptfs_inode)
232{
233 struct ecryptfs_inode_info *inode_info =
234 ecryptfs_inode_to_private(ecryptfs_inode);
Michael Halcrowda0102a2007-10-16 01:28:07 -0700235 mm_segment_t fs_save;
Tyler Hicks96a7b9c2009-09-16 19:04:20 -0500236 ssize_t rc;
Michael Halcrowda0102a2007-10-16 01:28:07 -0700237
238 mutex_lock(&inode_info->lower_file_mutex);
239 BUG_ON(!inode_info->lower_file);
240 inode_info->lower_file->f_pos = offset;
241 fs_save = get_fs();
242 set_fs(get_ds());
Tyler Hicks96a7b9c2009-09-16 19:04:20 -0500243 rc = vfs_read(inode_info->lower_file, data, size,
244 &inode_info->lower_file->f_pos);
Michael Halcrowda0102a2007-10-16 01:28:07 -0700245 set_fs(fs_save);
Michael Halcrowda0102a2007-10-16 01:28:07 -0700246 mutex_unlock(&inode_info->lower_file_mutex);
Michael Halcrowda0102a2007-10-16 01:28:07 -0700247 return rc;
248}
249
250/**
251 * ecryptfs_read_lower_page_segment
252 * @page_for_ecryptfs: The page into which data for eCryptfs will be
253 * written
254 * @offset_in_page: Offset in @page_for_ecryptfs from which to start
255 * writing
256 * @size: The number of bytes to write into @page_for_ecryptfs
257 * @ecryptfs_inode: The eCryptfs inode
258 *
259 * Determines the byte offset in the file for the given page and
260 * offset within the page, maps the page, and makes the call to read
261 * the contents of @page_for_ecryptfs from the lower inode.
262 *
263 * Returns zero on success; non-zero otherwise
264 */
265int ecryptfs_read_lower_page_segment(struct page *page_for_ecryptfs,
266 pgoff_t page_index,
267 size_t offset_in_page, size_t size,
268 struct inode *ecryptfs_inode)
269{
270 char *virt;
271 loff_t offset;
272 int rc;
273
Michael Halcrowd6a13c12007-10-16 01:28:12 -0700274 offset = ((((loff_t)page_index) << PAGE_CACHE_SHIFT) + offset_in_page);
Michael Halcrowda0102a2007-10-16 01:28:07 -0700275 virt = kmap(page_for_ecryptfs);
276 rc = ecryptfs_read_lower(virt, offset, size, ecryptfs_inode);
Tyler Hicks96a7b9c2009-09-16 19:04:20 -0500277 if (rc > 0)
278 rc = 0;
Michael Halcrowda0102a2007-10-16 01:28:07 -0700279 kunmap(page_for_ecryptfs);
Michael Halcrow16a72c42007-10-16 01:28:14 -0700280 flush_dcache_page(page_for_ecryptfs);
Michael Halcrowda0102a2007-10-16 01:28:07 -0700281 return rc;
282}
283
Adrian Bunk7896b632008-02-06 01:38:32 -0800284#if 0
Michael Halcrowda0102a2007-10-16 01:28:07 -0700285/**
286 * ecryptfs_read
287 * @data: The virtual address into which to write the data read (and
288 * possibly decrypted) from the lower file
289 * @offset: The offset in the decrypted view of the file from which to
290 * read into @data
291 * @size: The number of bytes to read into @data
292 * @ecryptfs_file: The eCryptfs file from which to read
293 *
294 * Read an arbitrary amount of data from an arbitrary location in the
295 * eCryptfs page cache. This is done on an extent-by-extent basis;
296 * individual extents are decrypted and read from the lower page
297 * cache (via VFS reads). This function takes care of all the
298 * address translation to locations in the lower filesystem.
299 *
300 * Returns zero on success; non-zero otherwise
301 */
302int ecryptfs_read(char *data, loff_t offset, size_t size,
303 struct file *ecryptfs_file)
304{
305 struct page *ecryptfs_page;
306 char *ecryptfs_page_virt;
Michael Halcrowd6a13c12007-10-16 01:28:12 -0700307 loff_t ecryptfs_file_size =
308 i_size_read(ecryptfs_file->f_dentry->d_inode);
Michael Halcrowda0102a2007-10-16 01:28:07 -0700309 loff_t data_offset = 0;
310 loff_t pos;
311 int rc = 0;
312
313 if ((offset + size) > ecryptfs_file_size) {
314 rc = -EINVAL;
315 printk(KERN_ERR "%s: Attempt to read data past the end of the "
316 "file; offset = [%lld]; size = [%td]; "
317 "ecryptfs_file_size = [%lld]\n",
Harvey Harrison18d1dbf2008-04-29 00:59:48 -0700318 __func__, offset, size, ecryptfs_file_size);
Michael Halcrowda0102a2007-10-16 01:28:07 -0700319 goto out;
320 }
321 pos = offset;
322 while (pos < (offset + size)) {
323 pgoff_t ecryptfs_page_idx = (pos >> PAGE_CACHE_SHIFT);
324 size_t start_offset_in_page = (pos & ~PAGE_CACHE_MASK);
325 size_t num_bytes = (PAGE_CACHE_SIZE - start_offset_in_page);
326 size_t total_remaining_bytes = ((offset + size) - pos);
327
328 if (num_bytes > total_remaining_bytes)
329 num_bytes = total_remaining_bytes;
Michael Halcrow16a72c42007-10-16 01:28:14 -0700330 ecryptfs_page = ecryptfs_get_locked_page(ecryptfs_file,
331 ecryptfs_page_idx);
Michael Halcrowda0102a2007-10-16 01:28:07 -0700332 if (IS_ERR(ecryptfs_page)) {
333 rc = PTR_ERR(ecryptfs_page);
334 printk(KERN_ERR "%s: Error getting page at "
335 "index [%ld] from eCryptfs inode "
Harvey Harrison18d1dbf2008-04-29 00:59:48 -0700336 "mapping; rc = [%d]\n", __func__,
Michael Halcrowda0102a2007-10-16 01:28:07 -0700337 ecryptfs_page_idx, rc);
338 goto out;
339 }
Michael Halcrowda0102a2007-10-16 01:28:07 -0700340 ecryptfs_page_virt = kmap_atomic(ecryptfs_page, KM_USER0);
341 memcpy((data + data_offset),
342 ((char *)ecryptfs_page_virt + start_offset_in_page),
343 num_bytes);
344 kunmap_atomic(ecryptfs_page_virt, KM_USER0);
Michael Halcrow16a72c42007-10-16 01:28:14 -0700345 flush_dcache_page(ecryptfs_page);
346 SetPageUptodate(ecryptfs_page);
347 unlock_page(ecryptfs_page);
Michael Halcrowda0102a2007-10-16 01:28:07 -0700348 page_cache_release(ecryptfs_page);
349 pos += num_bytes;
350 data_offset += num_bytes;
351 }
352out:
353 return rc;
354}
Adrian Bunk7896b632008-02-06 01:38:32 -0800355#endif /* 0 */