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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{
Tyler Hicksf61500e2011-08-04 22:58:51 -050042 struct file *lower_file;
Tyler Hicks96a7b9c2009-09-16 19:04:20 -050043 ssize_t rc;
Michael Halcrowda0102a2007-10-16 01:28:07 -070044
Tyler Hicksf61500e2011-08-04 22:58:51 -050045 lower_file = ecryptfs_inode_to_private(ecryptfs_inode)->lower_file;
46 if (!lower_file)
47 return -EIO;
Al Viro7bb307e2013-02-23 14:51:48 -050048 rc = kernel_write(lower_file, data, size, offset);
Michael Halcrowda0102a2007-10-16 01:28:07 -070049 mark_inode_dirty_sync(ecryptfs_inode);
50 return rc;
51}
52
53/**
54 * ecryptfs_write_lower_page_segment
55 * @ecryptfs_inode: The eCryptfs inode
56 * @page_for_lower: The page containing the data to be written to the
57 * lower file
58 * @offset_in_page: The offset in the @page_for_lower from which to
59 * start writing the data
60 * @size: The amount of data from @page_for_lower to write to the
61 * lower file
62 *
63 * Determines the byte offset in the file for the given page and
64 * offset within the page, maps the page, and makes the call to write
65 * the contents of @page_for_lower to the lower inode.
66 *
67 * Returns zero on success; non-zero otherwise
68 */
69int ecryptfs_write_lower_page_segment(struct inode *ecryptfs_inode,
70 struct page *page_for_lower,
71 size_t offset_in_page, size_t size)
72{
73 char *virt;
74 loff_t offset;
75 int rc;
76
Michael Halcrow8a146a22007-11-14 16:58:27 -080077 offset = ((((loff_t)page_for_lower->index) << PAGE_CACHE_SHIFT)
Michael Halcrowd6a13c12007-10-16 01:28:12 -070078 + offset_in_page);
Michael Halcrowda0102a2007-10-16 01:28:07 -070079 virt = kmap(page_for_lower);
80 rc = ecryptfs_write_lower(ecryptfs_inode, virt, offset, size);
Tyler Hicks96a7b9c2009-09-16 19:04:20 -050081 if (rc > 0)
82 rc = 0;
Michael Halcrowda0102a2007-10-16 01:28:07 -070083 kunmap(page_for_lower);
84 return rc;
85}
86
87/**
88 * ecryptfs_write
Al Viro48c1e442010-05-21 11:09:58 -040089 * @ecryptfs_inode: The eCryptfs file into which to write
Michael Halcrowda0102a2007-10-16 01:28:07 -070090 * @data: Virtual address where data to write is located
91 * @offset: Offset in the eCryptfs file at which to begin writing the
92 * data from @data
93 * @size: The number of bytes to write from @data
94 *
95 * Write an arbitrary amount of data to an arbitrary location in the
96 * eCryptfs inode page cache. This is done on a page-by-page, and then
97 * by an extent-by-extent, basis; individual extents are encrypted and
98 * written to the lower page cache (via VFS writes). This function
99 * takes care of all the address translation to locations in the lower
100 * filesystem; it also handles truncate events, writing out zeros
101 * where necessary.
102 *
103 * Returns zero on success; non-zero otherwise
104 */
Al Viro48c1e442010-05-21 11:09:58 -0400105int ecryptfs_write(struct inode *ecryptfs_inode, char *data, loff_t offset,
Michael Halcrowda0102a2007-10-16 01:28:07 -0700106 size_t size)
107{
108 struct page *ecryptfs_page;
Tyler Hicks13a791b2009-04-13 15:29:27 -0500109 struct ecryptfs_crypt_stat *crypt_stat;
Michael Halcrowda0102a2007-10-16 01:28:07 -0700110 char *ecryptfs_page_virt;
Tyler Hicks13a791b2009-04-13 15:29:27 -0500111 loff_t ecryptfs_file_size = i_size_read(ecryptfs_inode);
Michael Halcrowda0102a2007-10-16 01:28:07 -0700112 loff_t data_offset = 0;
113 loff_t pos;
114 int rc = 0;
115
Tyler Hicks13a791b2009-04-13 15:29:27 -0500116 crypt_stat = &ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat;
Eric Sandeen7a3f5952007-12-17 16:20:10 -0800117 /*
118 * if we are writing beyond current size, then start pos
119 * at the current size - we'll fill in zeros from there.
120 */
Michael Halcrowda0102a2007-10-16 01:28:07 -0700121 if (offset > ecryptfs_file_size)
122 pos = ecryptfs_file_size;
123 else
124 pos = offset;
125 while (pos < (offset + size)) {
126 pgoff_t ecryptfs_page_idx = (pos >> PAGE_CACHE_SHIFT);
127 size_t start_offset_in_page = (pos & ~PAGE_CACHE_MASK);
128 size_t num_bytes = (PAGE_CACHE_SIZE - start_offset_in_page);
Li Wang684a3ff2012-01-19 09:44:36 +0800129 loff_t total_remaining_bytes = ((offset + size) - pos);
Michael Halcrowda0102a2007-10-16 01:28:07 -0700130
Tyler Hicks5e6f0d72012-01-18 18:30:04 -0600131 if (fatal_signal_pending(current)) {
132 rc = -EINTR;
133 break;
134 }
135
Michael Halcrowda0102a2007-10-16 01:28:07 -0700136 if (num_bytes > total_remaining_bytes)
137 num_bytes = total_remaining_bytes;
138 if (pos < offset) {
Eric Sandeen7a3f5952007-12-17 16:20:10 -0800139 /* remaining zeros to write, up to destination offset */
Li Wang684a3ff2012-01-19 09:44:36 +0800140 loff_t total_remaining_zeros = (offset - pos);
Michael Halcrowda0102a2007-10-16 01:28:07 -0700141
142 if (num_bytes > total_remaining_zeros)
143 num_bytes = total_remaining_zeros;
144 }
Al Viro02bd9792010-05-21 11:02:14 -0400145 ecryptfs_page = ecryptfs_get_locked_page(ecryptfs_inode,
Michael Halcrow16a72c42007-10-16 01:28:14 -0700146 ecryptfs_page_idx);
Michael Halcrowda0102a2007-10-16 01:28:07 -0700147 if (IS_ERR(ecryptfs_page)) {
148 rc = PTR_ERR(ecryptfs_page);
149 printk(KERN_ERR "%s: Error getting page at "
150 "index [%ld] from eCryptfs inode "
Harvey Harrison18d1dbf2008-04-29 00:59:48 -0700151 "mapping; rc = [%d]\n", __func__,
Michael Halcrowda0102a2007-10-16 01:28:07 -0700152 ecryptfs_page_idx, rc);
153 goto out;
154 }
Cong Wang465c9342012-02-10 13:39:50 +0800155 ecryptfs_page_virt = kmap_atomic(ecryptfs_page);
Eric Sandeen7a3f5952007-12-17 16:20:10 -0800156
157 /*
158 * pos: where we're now writing, offset: where the request was
159 * If current pos is before request, we are filling zeros
160 * If we are at or beyond request, we are writing the *data*
161 * If we're in a fresh page beyond eof, zero it in either case
162 */
163 if (pos < offset || !start_offset_in_page) {
164 /* We are extending past the previous end of the file.
165 * Fill in zero values to the end of the page */
166 memset(((char *)ecryptfs_page_virt
167 + start_offset_in_page), 0,
168 PAGE_CACHE_SIZE - start_offset_in_page);
169 }
170
171 /* pos >= offset, we are now writing the data request */
Michael Halcrowda0102a2007-10-16 01:28:07 -0700172 if (pos >= offset) {
173 memcpy(((char *)ecryptfs_page_virt
174 + start_offset_in_page),
175 (data + data_offset), num_bytes);
176 data_offset += num_bytes;
Michael Halcrowda0102a2007-10-16 01:28:07 -0700177 }
Cong Wang465c9342012-02-10 13:39:50 +0800178 kunmap_atomic(ecryptfs_page_virt);
Michael Halcrowda0102a2007-10-16 01:28:07 -0700179 flush_dcache_page(ecryptfs_page);
Michael Halcrow16a72c42007-10-16 01:28:14 -0700180 SetPageUptodate(ecryptfs_page);
181 unlock_page(ecryptfs_page);
Tyler Hicks13a791b2009-04-13 15:29:27 -0500182 if (crypt_stat->flags & ECRYPTFS_ENCRYPTED)
183 rc = ecryptfs_encrypt_page(ecryptfs_page);
184 else
185 rc = ecryptfs_write_lower_page_segment(ecryptfs_inode,
186 ecryptfs_page,
187 start_offset_in_page,
188 data_offset);
Michael Halcrow16a72c42007-10-16 01:28:14 -0700189 page_cache_release(ecryptfs_page);
Michael Halcrowda0102a2007-10-16 01:28:07 -0700190 if (rc) {
191 printk(KERN_ERR "%s: Error encrypting "
Harvey Harrison18d1dbf2008-04-29 00:59:48 -0700192 "page; rc = [%d]\n", __func__, rc);
Michael Halcrowda0102a2007-10-16 01:28:07 -0700193 goto out;
194 }
Michael Halcrowda0102a2007-10-16 01:28:07 -0700195 pos += num_bytes;
196 }
Tyler Hicks5e6f0d72012-01-18 18:30:04 -0600197 if (pos > ecryptfs_file_size) {
198 i_size_write(ecryptfs_inode, pos);
Tyler Hicks13a791b2009-04-13 15:29:27 -0500199 if (crypt_stat->flags & ECRYPTFS_ENCRYPTED) {
Tyler Hicks5e6f0d72012-01-18 18:30:04 -0600200 int rc2;
201
202 rc2 = ecryptfs_write_inode_size_to_metadata(
Tyler Hicks13a791b2009-04-13 15:29:27 -0500203 ecryptfs_inode);
Tyler Hicks5e6f0d72012-01-18 18:30:04 -0600204 if (rc2) {
Tyler Hicks13a791b2009-04-13 15:29:27 -0500205 printk(KERN_ERR "Problem with "
206 "ecryptfs_write_inode_size_to_metadata; "
Tyler Hicks5e6f0d72012-01-18 18:30:04 -0600207 "rc = [%d]\n", rc2);
208 if (!rc)
209 rc = rc2;
Tyler Hicks13a791b2009-04-13 15:29:27 -0500210 goto out;
211 }
Michael Halcrowda0102a2007-10-16 01:28:07 -0700212 }
213 }
214out:
215 return rc;
216}
217
218/**
219 * ecryptfs_read_lower
220 * @data: The read data is stored here by this function
221 * @offset: Byte offset in the lower file from which to read the data
222 * @size: Number of bytes to read from @offset of the lower file and
223 * store into @data
224 * @ecryptfs_inode: The eCryptfs inode
225 *
226 * Read @size bytes of data at byte offset @offset from the lower
227 * inode into memory location @data.
228 *
Tyler Hicks96a7b9c2009-09-16 19:04:20 -0500229 * Returns bytes read on success; 0 on EOF; less than zero on error
Michael Halcrowda0102a2007-10-16 01:28:07 -0700230 */
231int ecryptfs_read_lower(char *data, loff_t offset, size_t size,
232 struct inode *ecryptfs_inode)
233{
Tyler Hicksf61500e2011-08-04 22:58:51 -0500234 struct file *lower_file;
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
Tyler Hicksf61500e2011-08-04 22:58:51 -0500238 lower_file = ecryptfs_inode_to_private(ecryptfs_inode)->lower_file;
239 if (!lower_file)
240 return -EIO;
Michael Halcrowda0102a2007-10-16 01:28:07 -0700241 fs_save = get_fs();
242 set_fs(get_ds());
Tyler Hicksf61500e2011-08-04 22:58:51 -0500243 rc = vfs_read(lower_file, data, size, &offset);
Michael Halcrowda0102a2007-10-16 01:28:07 -0700244 set_fs(fs_save);
Michael Halcrowda0102a2007-10-16 01:28:07 -0700245 return rc;
246}
247
248/**
249 * ecryptfs_read_lower_page_segment
250 * @page_for_ecryptfs: The page into which data for eCryptfs will be
251 * written
252 * @offset_in_page: Offset in @page_for_ecryptfs from which to start
253 * writing
254 * @size: The number of bytes to write into @page_for_ecryptfs
255 * @ecryptfs_inode: The eCryptfs inode
256 *
257 * Determines the byte offset in the file for the given page and
258 * offset within the page, maps the page, and makes the call to read
259 * the contents of @page_for_ecryptfs from the lower inode.
260 *
261 * Returns zero on success; non-zero otherwise
262 */
263int ecryptfs_read_lower_page_segment(struct page *page_for_ecryptfs,
264 pgoff_t page_index,
265 size_t offset_in_page, size_t size,
266 struct inode *ecryptfs_inode)
267{
268 char *virt;
269 loff_t offset;
270 int rc;
271
Michael Halcrowd6a13c12007-10-16 01:28:12 -0700272 offset = ((((loff_t)page_index) << PAGE_CACHE_SHIFT) + offset_in_page);
Michael Halcrowda0102a2007-10-16 01:28:07 -0700273 virt = kmap(page_for_ecryptfs);
274 rc = ecryptfs_read_lower(virt, offset, size, ecryptfs_inode);
Tyler Hicks96a7b9c2009-09-16 19:04:20 -0500275 if (rc > 0)
276 rc = 0;
Michael Halcrowda0102a2007-10-16 01:28:07 -0700277 kunmap(page_for_ecryptfs);
Michael Halcrow16a72c42007-10-16 01:28:14 -0700278 flush_dcache_page(page_for_ecryptfs);
Michael Halcrowda0102a2007-10-16 01:28:07 -0700279 return rc;
280}