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1 : : /**
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 bytes written on success; less than zero on error
38 : : */
39 : 0 : int ecryptfs_write_lower(struct inode *ecryptfs_inode, char *data,
40 : : loff_t offset, size_t size)
41 : : {
42 : : struct file *lower_file;
43 : : ssize_t rc;
44 : :
45 : 0 : lower_file = ecryptfs_inode_to_private(ecryptfs_inode)->lower_file;
46 [ # # ]: 0 : if (!lower_file)
47 : : return -EIO;
48 : 0 : rc = kernel_write(lower_file, data, size, offset);
49 : : mark_inode_dirty_sync(ecryptfs_inode);
50 : 0 : 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 : : */
69 : 0 : int 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 : :
77 : 0 : offset = ((((loff_t)page_for_lower->index) << PAGE_CACHE_SHIFT)
78 : 0 : + offset_in_page);
79 : 0 : virt = kmap(page_for_lower);
80 : 0 : rc = ecryptfs_write_lower(ecryptfs_inode, virt, offset, size);
81 [ # # ]: 0 : if (rc > 0)
82 : : rc = 0;
83 : 0 : kunmap(page_for_lower);
84 : 0 : return rc;
85 : : }
86 : :
87 : : /**
88 : : * ecryptfs_write
89 : : * @ecryptfs_inode: The eCryptfs file into which to write
90 : : * @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 : : */
105 : 0 : int ecryptfs_write(struct inode *ecryptfs_inode, char *data, loff_t offset,
106 : : size_t size)
107 : : {
108 : : struct page *ecryptfs_page;
109 : : struct ecryptfs_crypt_stat *crypt_stat;
110 : : char *ecryptfs_page_virt;
111 : : loff_t ecryptfs_file_size = i_size_read(ecryptfs_inode);
112 : : loff_t data_offset = 0;
113 : : loff_t pos;
114 : : int rc = 0;
115 : :
116 : : crypt_stat = &ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat;
117 : : /*
118 : : * if we are writing beyond current size, then start pos
119 : : * at the current size - we'll fill in zeros from there.
120 : : */
121 [ # # ]: 0 : if (offset > ecryptfs_file_size)
122 : : pos = ecryptfs_file_size;
123 : : else
124 : : pos = offset;
125 [ # # ]: 0 : while (pos < (offset + size)) {
126 : 0 : pgoff_t ecryptfs_page_idx = (pos >> PAGE_CACHE_SHIFT);
127 : 0 : size_t start_offset_in_page = (pos & ~PAGE_CACHE_MASK);
128 : 0 : size_t num_bytes = (PAGE_CACHE_SIZE - start_offset_in_page);
129 : 0 : loff_t total_remaining_bytes = ((offset + size) - pos);
130 : :
131 [ # # ]: 0 : if (fatal_signal_pending(current)) {
132 : : rc = -EINTR;
133 : : break;
134 : : }
135 : :
136 [ # # ]: 0 : if (num_bytes > total_remaining_bytes)
137 : 0 : num_bytes = total_remaining_bytes;
138 [ # # ]: 0 : if (pos < offset) {
139 : : /* remaining zeros to write, up to destination offset */
140 : 0 : loff_t total_remaining_zeros = (offset - pos);
141 : :
142 [ # # ]: 0 : if (num_bytes > total_remaining_zeros)
143 : 0 : num_bytes = total_remaining_zeros;
144 : : }
145 : 0 : ecryptfs_page = ecryptfs_get_locked_page(ecryptfs_inode,
146 : : ecryptfs_page_idx);
147 [ # # ]: 0 : if (IS_ERR(ecryptfs_page)) {
148 : : rc = PTR_ERR(ecryptfs_page);
149 : 0 : printk(KERN_ERR "%s: Error getting page at "
150 : : "index [%ld] from eCryptfs inode "
151 : : "mapping; rc = [%d]\n", __func__,
152 : : ecryptfs_page_idx, rc);
153 : 0 : goto out;
154 : : }
155 : 0 : ecryptfs_page_virt = kmap_atomic(ecryptfs_page);
156 : :
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 [ # # ]: 0 : 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 [ # # ]: 0 : 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 */
172 [ # # ]: 0 : if (pos >= offset) {
173 : 0 : memcpy(((char *)ecryptfs_page_virt
174 : : + start_offset_in_page),
175 : : (data + data_offset), num_bytes);
176 : 0 : data_offset += num_bytes;
177 : : }
178 : 0 : kunmap_atomic(ecryptfs_page_virt);
179 : 0 : flush_dcache_page(ecryptfs_page);
180 : : SetPageUptodate(ecryptfs_page);
181 : 0 : unlock_page(ecryptfs_page);
182 [ # # ]: 0 : if (crypt_stat->flags & ECRYPTFS_ENCRYPTED)
183 : 0 : rc = ecryptfs_encrypt_page(ecryptfs_page);
184 : : else
185 : 0 : rc = ecryptfs_write_lower_page_segment(ecryptfs_inode,
186 : : ecryptfs_page,
187 : : start_offset_in_page,
188 : : data_offset);
189 : 0 : page_cache_release(ecryptfs_page);
190 [ # # ]: 0 : if (rc) {
191 : 0 : printk(KERN_ERR "%s: Error encrypting "
192 : : "page; rc = [%d]\n", __func__, rc);
193 : 0 : goto out;
194 : : }
195 : 0 : pos += num_bytes;
196 : : }
197 [ # # ]: 0 : if (pos > ecryptfs_file_size) {
198 : : i_size_write(ecryptfs_inode, pos);
199 [ # # ]: 0 : if (crypt_stat->flags & ECRYPTFS_ENCRYPTED) {
200 : : int rc2;
201 : :
202 : 0 : rc2 = ecryptfs_write_inode_size_to_metadata(
203 : : ecryptfs_inode);
204 [ # # ]: 0 : if (rc2) {
205 : 0 : printk(KERN_ERR "Problem with "
206 : : "ecryptfs_write_inode_size_to_metadata; "
207 : : "rc = [%d]\n", rc2);
208 [ # # ]: 0 : if (!rc)
209 : : rc = rc2;
210 : : goto out;
211 : : }
212 : : }
213 : : }
214 : : out:
215 : 0 : 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 : : *
229 : : * Returns bytes read on success; 0 on EOF; less than zero on error
230 : : */
231 : 0 : int ecryptfs_read_lower(char *data, loff_t offset, size_t size,
232 : : struct inode *ecryptfs_inode)
233 : : {
234 : : struct file *lower_file;
235 : 0 : lower_file = ecryptfs_inode_to_private(ecryptfs_inode)->lower_file;
236 [ # # ][ # # ]: 0 : if (!lower_file)
237 : : return -EIO;
238 : 0 : return kernel_read(lower_file, offset, data, size);
239 : : }
240 : :
241 : : /**
242 : : * ecryptfs_read_lower_page_segment
243 : : * @page_for_ecryptfs: The page into which data for eCryptfs will be
244 : : * written
245 : : * @offset_in_page: Offset in @page_for_ecryptfs from which to start
246 : : * writing
247 : : * @size: The number of bytes to write into @page_for_ecryptfs
248 : : * @ecryptfs_inode: The eCryptfs inode
249 : : *
250 : : * Determines the byte offset in the file for the given page and
251 : : * offset within the page, maps the page, and makes the call to read
252 : : * the contents of @page_for_ecryptfs from the lower inode.
253 : : *
254 : : * Returns zero on success; non-zero otherwise
255 : : */
256 : 0 : int ecryptfs_read_lower_page_segment(struct page *page_for_ecryptfs,
257 : : pgoff_t page_index,
258 : : size_t offset_in_page, size_t size,
259 : : struct inode *ecryptfs_inode)
260 : : {
261 : : char *virt;
262 : : loff_t offset;
263 : : int rc;
264 : :
265 : 0 : offset = ((((loff_t)page_index) << PAGE_CACHE_SHIFT) + offset_in_page);
266 : 0 : virt = kmap(page_for_ecryptfs);
267 : : rc = ecryptfs_read_lower(virt, offset, size, ecryptfs_inode);
268 [ # # ]: 0 : if (rc > 0)
269 : : rc = 0;
270 : 0 : kunmap(page_for_ecryptfs);
271 : 0 : flush_dcache_page(page_for_ecryptfs);
272 : 0 : return rc;
273 : : }
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