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da0102a1 MH |
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 zero on success; non-zero on error | |
38 | */ | |
39 | int 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]; " | |
18d1dbf1 | 58 | "expected [%td]\n", __func__, octets_written, size); |
da0102a1 MH |
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 | */ | |
82 | int 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 | ||
8a146a2b | 90 | offset = ((((loff_t)page_for_lower->index) << PAGE_CACHE_SHIFT) |
d6a13c17 | 91 | + offset_in_page); |
da0102a1 MH |
92 | 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 | */ | |
116 | int 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; | |
d6a13c17 MH |
121 | loff_t ecryptfs_file_size = |
122 | i_size_read(ecryptfs_file->f_dentry->d_inode); | |
da0102a1 MH |
123 | loff_t data_offset = 0; |
124 | loff_t pos; | |
125 | int rc = 0; | |
126 | ||
7a3f595c ES |
127 | /* |
128 | * if we are writing beyond current size, then start pos | |
129 | * at the current size - we'll fill in zeros from there. | |
130 | */ | |
da0102a1 MH |
131 | 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) { | |
7a3f595c | 144 | /* remaining zeros to write, up to destination offset */ |
da0102a1 MH |
145 | size_t total_remaining_zeros = (offset - pos); |
146 | ||
147 | if (num_bytes > total_remaining_zeros) | |
148 | num_bytes = total_remaining_zeros; | |
149 | } | |
16a72c45 MH |
150 | ecryptfs_page = ecryptfs_get_locked_page(ecryptfs_file, |
151 | ecryptfs_page_idx); | |
da0102a1 MH |
152 | 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 " | |
18d1dbf1 | 156 | "mapping; rc = [%d]\n", __func__, |
da0102a1 MH |
157 | ecryptfs_page_idx, rc); |
158 | goto out; | |
159 | } | |
da0102a1 | 160 | ecryptfs_page_virt = kmap_atomic(ecryptfs_page, KM_USER0); |
7a3f595c ES |
161 | |
162 | /* | |
163 | * pos: where we're now writing, offset: where the request was | |
164 | * If current pos is before request, we are filling zeros | |
165 | * If we are at or beyond request, we are writing the *data* | |
166 | * If we're in a fresh page beyond eof, zero it in either case | |
167 | */ | |
168 | if (pos < offset || !start_offset_in_page) { | |
169 | /* We are extending past the previous end of the file. | |
170 | * Fill in zero values to the end of the page */ | |
171 | memset(((char *)ecryptfs_page_virt | |
172 | + start_offset_in_page), 0, | |
173 | PAGE_CACHE_SIZE - start_offset_in_page); | |
174 | } | |
175 | ||
176 | /* pos >= offset, we are now writing the data request */ | |
da0102a1 MH |
177 | if (pos >= offset) { |
178 | memcpy(((char *)ecryptfs_page_virt | |
179 | + start_offset_in_page), | |
180 | (data + data_offset), num_bytes); | |
181 | data_offset += num_bytes; | |
da0102a1 MH |
182 | } |
183 | kunmap_atomic(ecryptfs_page_virt, KM_USER0); | |
184 | flush_dcache_page(ecryptfs_page); | |
16a72c45 MH |
185 | SetPageUptodate(ecryptfs_page); |
186 | unlock_page(ecryptfs_page); | |
0216f7f7 | 187 | rc = ecryptfs_encrypt_page(ecryptfs_page); |
16a72c45 | 188 | page_cache_release(ecryptfs_page); |
da0102a1 MH |
189 | if (rc) { |
190 | printk(KERN_ERR "%s: Error encrypting " | |
18d1dbf1 | 191 | "page; rc = [%d]\n", __func__, rc); |
da0102a1 MH |
192 | goto out; |
193 | } | |
da0102a1 MH |
194 | pos += num_bytes; |
195 | } | |
196 | if ((offset + size) > ecryptfs_file_size) { | |
197 | i_size_write(ecryptfs_file->f_dentry->d_inode, (offset + size)); | |
0216f7f7 MH |
198 | rc = ecryptfs_write_inode_size_to_metadata( |
199 | ecryptfs_file->f_dentry->d_inode); | |
da0102a1 MH |
200 | if (rc) { |
201 | printk(KERN_ERR "Problem with " | |
202 | "ecryptfs_write_inode_size_to_metadata; " | |
203 | "rc = [%d]\n", rc); | |
204 | goto out; | |
205 | } | |
206 | } | |
207 | out: | |
208 | return rc; | |
209 | } | |
210 | ||
211 | /** | |
212 | * ecryptfs_read_lower | |
213 | * @data: The read data is stored here by this function | |
214 | * @offset: Byte offset in the lower file from which to read the data | |
215 | * @size: Number of bytes to read from @offset of the lower file and | |
216 | * store into @data | |
217 | * @ecryptfs_inode: The eCryptfs inode | |
218 | * | |
219 | * Read @size bytes of data at byte offset @offset from the lower | |
220 | * inode into memory location @data. | |
221 | * | |
222 | * Returns zero on success; non-zero on error | |
223 | */ | |
224 | int ecryptfs_read_lower(char *data, loff_t offset, size_t size, | |
225 | struct inode *ecryptfs_inode) | |
226 | { | |
227 | struct ecryptfs_inode_info *inode_info = | |
228 | ecryptfs_inode_to_private(ecryptfs_inode); | |
229 | ssize_t octets_read; | |
230 | mm_segment_t fs_save; | |
da0102a1 MH |
231 | int rc = 0; |
232 | ||
233 | mutex_lock(&inode_info->lower_file_mutex); | |
234 | BUG_ON(!inode_info->lower_file); | |
235 | inode_info->lower_file->f_pos = offset; | |
236 | fs_save = get_fs(); | |
237 | set_fs(get_ds()); | |
238 | octets_read = vfs_read(inode_info->lower_file, data, size, | |
239 | &inode_info->lower_file->f_pos); | |
240 | set_fs(fs_save); | |
241 | if (octets_read < 0) { | |
242 | printk(KERN_ERR "%s: octets_read = [%td]; " | |
18d1dbf1 | 243 | "expected [%td]\n", __func__, octets_read, size); |
da0102a1 MH |
244 | rc = -EINVAL; |
245 | } | |
246 | mutex_unlock(&inode_info->lower_file_mutex); | |
da0102a1 MH |
247 | 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 | */ | |
265 | int 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 | ||
d6a13c17 | 274 | offset = ((((loff_t)page_index) << PAGE_CACHE_SHIFT) + offset_in_page); |
da0102a1 MH |
275 | virt = kmap(page_for_ecryptfs); |
276 | rc = ecryptfs_read_lower(virt, offset, size, ecryptfs_inode); | |
277 | kunmap(page_for_ecryptfs); | |
16a72c45 | 278 | flush_dcache_page(page_for_ecryptfs); |
da0102a1 MH |
279 | return rc; |
280 | } | |
281 | ||
7896b631 | 282 | #if 0 |
da0102a1 MH |
283 | /** |
284 | * ecryptfs_read | |
285 | * @data: The virtual address into which to write the data read (and | |
286 | * possibly decrypted) from the lower file | |
287 | * @offset: The offset in the decrypted view of the file from which to | |
288 | * read into @data | |
289 | * @size: The number of bytes to read into @data | |
290 | * @ecryptfs_file: The eCryptfs file from which to read | |
291 | * | |
292 | * Read an arbitrary amount of data from an arbitrary location in the | |
293 | * eCryptfs page cache. This is done on an extent-by-extent basis; | |
294 | * individual extents are decrypted and read from the lower page | |
295 | * cache (via VFS reads). This function takes care of all the | |
296 | * address translation to locations in the lower filesystem. | |
297 | * | |
298 | * Returns zero on success; non-zero otherwise | |
299 | */ | |
300 | int ecryptfs_read(char *data, loff_t offset, size_t size, | |
301 | struct file *ecryptfs_file) | |
302 | { | |
303 | struct page *ecryptfs_page; | |
304 | char *ecryptfs_page_virt; | |
d6a13c17 MH |
305 | loff_t ecryptfs_file_size = |
306 | i_size_read(ecryptfs_file->f_dentry->d_inode); | |
da0102a1 MH |
307 | loff_t data_offset = 0; |
308 | loff_t pos; | |
309 | int rc = 0; | |
310 | ||
311 | if ((offset + size) > ecryptfs_file_size) { | |
312 | rc = -EINVAL; | |
313 | printk(KERN_ERR "%s: Attempt to read data past the end of the " | |
314 | "file; offset = [%lld]; size = [%td]; " | |
315 | "ecryptfs_file_size = [%lld]\n", | |
18d1dbf1 | 316 | __func__, offset, size, ecryptfs_file_size); |
da0102a1 MH |
317 | goto out; |
318 | } | |
319 | pos = offset; | |
320 | while (pos < (offset + size)) { | |
321 | pgoff_t ecryptfs_page_idx = (pos >> PAGE_CACHE_SHIFT); | |
322 | size_t start_offset_in_page = (pos & ~PAGE_CACHE_MASK); | |
323 | size_t num_bytes = (PAGE_CACHE_SIZE - start_offset_in_page); | |
324 | size_t total_remaining_bytes = ((offset + size) - pos); | |
325 | ||
326 | if (num_bytes > total_remaining_bytes) | |
327 | num_bytes = total_remaining_bytes; | |
16a72c45 MH |
328 | ecryptfs_page = ecryptfs_get_locked_page(ecryptfs_file, |
329 | ecryptfs_page_idx); | |
da0102a1 MH |
330 | if (IS_ERR(ecryptfs_page)) { |
331 | rc = PTR_ERR(ecryptfs_page); | |
332 | printk(KERN_ERR "%s: Error getting page at " | |
333 | "index [%ld] from eCryptfs inode " | |
18d1dbf1 | 334 | "mapping; rc = [%d]\n", __func__, |
da0102a1 MH |
335 | ecryptfs_page_idx, rc); |
336 | goto out; | |
337 | } | |
da0102a1 MH |
338 | ecryptfs_page_virt = kmap_atomic(ecryptfs_page, KM_USER0); |
339 | memcpy((data + data_offset), | |
340 | ((char *)ecryptfs_page_virt + start_offset_in_page), | |
341 | num_bytes); | |
342 | kunmap_atomic(ecryptfs_page_virt, KM_USER0); | |
16a72c45 MH |
343 | flush_dcache_page(ecryptfs_page); |
344 | SetPageUptodate(ecryptfs_page); | |
345 | unlock_page(ecryptfs_page); | |
da0102a1 MH |
346 | page_cache_release(ecryptfs_page); |
347 | pos += num_bytes; | |
348 | data_offset += num_bytes; | |
349 | } | |
350 | out: | |
351 | return rc; | |
352 | } | |
7896b631 | 353 | #endif /* 0 */ |