Commit | Line | Data |
---|---|---|
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 | * | |
96a7b9c2 | 37 | * Returns bytes written on success; less than zero on error |
da0102a1 MH |
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; | |
da0102a1 | 43 | mm_segment_t fs_save; |
96a7b9c2 | 44 | ssize_t rc; |
da0102a1 MH |
45 | |
46 | inode_info = ecryptfs_inode_to_private(ecryptfs_inode); | |
da0102a1 | 47 | BUG_ON(!inode_info->lower_file); |
da0102a1 MH |
48 | fs_save = get_fs(); |
49 | set_fs(get_ds()); | |
57db4e8d | 50 | rc = vfs_write(inode_info->lower_file, data, size, &offset); |
da0102a1 | 51 | set_fs(fs_save); |
da0102a1 MH |
52 | mark_inode_dirty_sync(ecryptfs_inode); |
53 | return rc; | |
54 | } | |
55 | ||
56 | /** | |
57 | * ecryptfs_write_lower_page_segment | |
58 | * @ecryptfs_inode: The eCryptfs inode | |
59 | * @page_for_lower: The page containing the data to be written to the | |
60 | * lower file | |
61 | * @offset_in_page: The offset in the @page_for_lower from which to | |
62 | * start writing the data | |
63 | * @size: The amount of data from @page_for_lower to write to the | |
64 | * lower file | |
65 | * | |
66 | * Determines the byte offset in the file for the given page and | |
67 | * offset within the page, maps the page, and makes the call to write | |
68 | * the contents of @page_for_lower to the lower inode. | |
69 | * | |
70 | * Returns zero on success; non-zero otherwise | |
71 | */ | |
72 | int ecryptfs_write_lower_page_segment(struct inode *ecryptfs_inode, | |
73 | struct page *page_for_lower, | |
74 | size_t offset_in_page, size_t size) | |
75 | { | |
76 | char *virt; | |
77 | loff_t offset; | |
78 | int rc; | |
79 | ||
8a146a2b | 80 | offset = ((((loff_t)page_for_lower->index) << PAGE_CACHE_SHIFT) |
d6a13c17 | 81 | + offset_in_page); |
da0102a1 MH |
82 | virt = kmap(page_for_lower); |
83 | rc = ecryptfs_write_lower(ecryptfs_inode, virt, offset, size); | |
96a7b9c2 TH |
84 | if (rc > 0) |
85 | rc = 0; | |
da0102a1 MH |
86 | kunmap(page_for_lower); |
87 | return rc; | |
88 | } | |
89 | ||
90 | /** | |
91 | * ecryptfs_write | |
48c1e44a | 92 | * @ecryptfs_inode: The eCryptfs file into which to write |
da0102a1 MH |
93 | * @data: Virtual address where data to write is located |
94 | * @offset: Offset in the eCryptfs file at which to begin writing the | |
95 | * data from @data | |
96 | * @size: The number of bytes to write from @data | |
97 | * | |
98 | * Write an arbitrary amount of data to an arbitrary location in the | |
99 | * eCryptfs inode page cache. This is done on a page-by-page, and then | |
100 | * by an extent-by-extent, basis; individual extents are encrypted and | |
101 | * written to the lower page cache (via VFS writes). This function | |
102 | * takes care of all the address translation to locations in the lower | |
103 | * filesystem; it also handles truncate events, writing out zeros | |
104 | * where necessary. | |
105 | * | |
106 | * Returns zero on success; non-zero otherwise | |
107 | */ | |
48c1e44a | 108 | int ecryptfs_write(struct inode *ecryptfs_inode, char *data, loff_t offset, |
da0102a1 MH |
109 | size_t size) |
110 | { | |
111 | struct page *ecryptfs_page; | |
13a791b4 | 112 | struct ecryptfs_crypt_stat *crypt_stat; |
da0102a1 | 113 | char *ecryptfs_page_virt; |
13a791b4 | 114 | loff_t ecryptfs_file_size = i_size_read(ecryptfs_inode); |
da0102a1 MH |
115 | loff_t data_offset = 0; |
116 | loff_t pos; | |
117 | int rc = 0; | |
118 | ||
13a791b4 | 119 | crypt_stat = &ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat; |
7a3f595c ES |
120 | /* |
121 | * if we are writing beyond current size, then start pos | |
122 | * at the current size - we'll fill in zeros from there. | |
123 | */ | |
da0102a1 MH |
124 | if (offset > ecryptfs_file_size) |
125 | pos = ecryptfs_file_size; | |
126 | else | |
127 | pos = offset; | |
128 | while (pos < (offset + size)) { | |
129 | pgoff_t ecryptfs_page_idx = (pos >> PAGE_CACHE_SHIFT); | |
130 | size_t start_offset_in_page = (pos & ~PAGE_CACHE_MASK); | |
131 | size_t num_bytes = (PAGE_CACHE_SIZE - start_offset_in_page); | |
132 | size_t total_remaining_bytes = ((offset + size) - pos); | |
133 | ||
134 | if (num_bytes > total_remaining_bytes) | |
135 | num_bytes = total_remaining_bytes; | |
136 | if (pos < offset) { | |
7a3f595c | 137 | /* remaining zeros to write, up to destination offset */ |
da0102a1 MH |
138 | size_t total_remaining_zeros = (offset - pos); |
139 | ||
140 | if (num_bytes > total_remaining_zeros) | |
141 | num_bytes = total_remaining_zeros; | |
142 | } | |
02bd9799 | 143 | ecryptfs_page = ecryptfs_get_locked_page(ecryptfs_inode, |
16a72c45 | 144 | ecryptfs_page_idx); |
da0102a1 MH |
145 | if (IS_ERR(ecryptfs_page)) { |
146 | rc = PTR_ERR(ecryptfs_page); | |
147 | printk(KERN_ERR "%s: Error getting page at " | |
148 | "index [%ld] from eCryptfs inode " | |
18d1dbf1 | 149 | "mapping; rc = [%d]\n", __func__, |
da0102a1 MH |
150 | ecryptfs_page_idx, rc); |
151 | goto out; | |
152 | } | |
da0102a1 | 153 | ecryptfs_page_virt = kmap_atomic(ecryptfs_page, KM_USER0); |
7a3f595c ES |
154 | |
155 | /* | |
156 | * pos: where we're now writing, offset: where the request was | |
157 | * If current pos is before request, we are filling zeros | |
158 | * If we are at or beyond request, we are writing the *data* | |
159 | * If we're in a fresh page beyond eof, zero it in either case | |
160 | */ | |
161 | if (pos < offset || !start_offset_in_page) { | |
162 | /* We are extending past the previous end of the file. | |
163 | * Fill in zero values to the end of the page */ | |
164 | memset(((char *)ecryptfs_page_virt | |
165 | + start_offset_in_page), 0, | |
166 | PAGE_CACHE_SIZE - start_offset_in_page); | |
167 | } | |
168 | ||
169 | /* pos >= offset, we are now writing the data request */ | |
da0102a1 MH |
170 | if (pos >= offset) { |
171 | memcpy(((char *)ecryptfs_page_virt | |
172 | + start_offset_in_page), | |
173 | (data + data_offset), num_bytes); | |
174 | data_offset += num_bytes; | |
da0102a1 MH |
175 | } |
176 | kunmap_atomic(ecryptfs_page_virt, KM_USER0); | |
177 | flush_dcache_page(ecryptfs_page); | |
16a72c45 MH |
178 | SetPageUptodate(ecryptfs_page); |
179 | unlock_page(ecryptfs_page); | |
13a791b4 TH |
180 | if (crypt_stat->flags & ECRYPTFS_ENCRYPTED) |
181 | rc = ecryptfs_encrypt_page(ecryptfs_page); | |
182 | else | |
183 | rc = ecryptfs_write_lower_page_segment(ecryptfs_inode, | |
184 | ecryptfs_page, | |
185 | start_offset_in_page, | |
186 | data_offset); | |
16a72c45 | 187 | page_cache_release(ecryptfs_page); |
da0102a1 MH |
188 | if (rc) { |
189 | printk(KERN_ERR "%s: Error encrypting " | |
18d1dbf1 | 190 | "page; rc = [%d]\n", __func__, rc); |
da0102a1 MH |
191 | goto out; |
192 | } | |
da0102a1 MH |
193 | pos += num_bytes; |
194 | } | |
195 | if ((offset + size) > ecryptfs_file_size) { | |
13a791b4 TH |
196 | i_size_write(ecryptfs_inode, (offset + size)); |
197 | if (crypt_stat->flags & ECRYPTFS_ENCRYPTED) { | |
198 | rc = ecryptfs_write_inode_size_to_metadata( | |
199 | ecryptfs_inode); | |
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 | } | |
da0102a1 MH |
206 | } |
207 | } | |
208 | out: | |
209 | return rc; | |
210 | } | |
211 | ||
212 | /** | |
213 | * ecryptfs_read_lower | |
214 | * @data: The read data is stored here by this function | |
215 | * @offset: Byte offset in the lower file from which to read the data | |
216 | * @size: Number of bytes to read from @offset of the lower file and | |
217 | * store into @data | |
218 | * @ecryptfs_inode: The eCryptfs inode | |
219 | * | |
220 | * Read @size bytes of data at byte offset @offset from the lower | |
221 | * inode into memory location @data. | |
222 | * | |
96a7b9c2 | 223 | * Returns bytes read on success; 0 on EOF; less than zero on error |
da0102a1 MH |
224 | */ |
225 | int ecryptfs_read_lower(char *data, loff_t offset, size_t size, | |
226 | struct inode *ecryptfs_inode) | |
227 | { | |
228 | struct ecryptfs_inode_info *inode_info = | |
229 | ecryptfs_inode_to_private(ecryptfs_inode); | |
da0102a1 | 230 | mm_segment_t fs_save; |
96a7b9c2 | 231 | ssize_t rc; |
da0102a1 | 232 | |
da0102a1 | 233 | BUG_ON(!inode_info->lower_file); |
da0102a1 MH |
234 | fs_save = get_fs(); |
235 | set_fs(get_ds()); | |
57db4e8d | 236 | rc = vfs_read(inode_info->lower_file, data, size, &offset); |
da0102a1 | 237 | set_fs(fs_save); |
da0102a1 MH |
238 | return rc; |
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 | 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 | ||
d6a13c17 | 265 | offset = ((((loff_t)page_index) << PAGE_CACHE_SHIFT) + offset_in_page); |
da0102a1 MH |
266 | virt = kmap(page_for_ecryptfs); |
267 | rc = ecryptfs_read_lower(virt, offset, size, ecryptfs_inode); | |
96a7b9c2 TH |
268 | if (rc > 0) |
269 | rc = 0; | |
da0102a1 | 270 | kunmap(page_for_ecryptfs); |
16a72c45 | 271 | flush_dcache_page(page_for_ecryptfs); |
da0102a1 MH |
272 | return rc; |
273 | } | |
274 | ||
7896b631 | 275 | #if 0 |
da0102a1 MH |
276 | /** |
277 | * ecryptfs_read | |
278 | * @data: The virtual address into which to write the data read (and | |
279 | * possibly decrypted) from the lower file | |
280 | * @offset: The offset in the decrypted view of the file from which to | |
281 | * read into @data | |
282 | * @size: The number of bytes to read into @data | |
283 | * @ecryptfs_file: The eCryptfs file from which to read | |
284 | * | |
285 | * Read an arbitrary amount of data from an arbitrary location in the | |
286 | * eCryptfs page cache. This is done on an extent-by-extent basis; | |
287 | * individual extents are decrypted and read from the lower page | |
288 | * cache (via VFS reads). This function takes care of all the | |
289 | * address translation to locations in the lower filesystem. | |
290 | * | |
291 | * Returns zero on success; non-zero otherwise | |
292 | */ | |
293 | int ecryptfs_read(char *data, loff_t offset, size_t size, | |
294 | struct file *ecryptfs_file) | |
295 | { | |
02bd9799 | 296 | struct inode *ecryptfs_inode = ecryptfs_file->f_dentry->d_inode; |
da0102a1 MH |
297 | struct page *ecryptfs_page; |
298 | char *ecryptfs_page_virt; | |
02bd9799 | 299 | loff_t ecryptfs_file_size = i_size_read(ecryptfs_inode); |
da0102a1 MH |
300 | loff_t data_offset = 0; |
301 | loff_t pos; | |
302 | int rc = 0; | |
303 | ||
304 | if ((offset + size) > ecryptfs_file_size) { | |
305 | rc = -EINVAL; | |
306 | printk(KERN_ERR "%s: Attempt to read data past the end of the " | |
307 | "file; offset = [%lld]; size = [%td]; " | |
308 | "ecryptfs_file_size = [%lld]\n", | |
18d1dbf1 | 309 | __func__, offset, size, ecryptfs_file_size); |
da0102a1 MH |
310 | goto out; |
311 | } | |
312 | pos = offset; | |
313 | while (pos < (offset + size)) { | |
314 | pgoff_t ecryptfs_page_idx = (pos >> PAGE_CACHE_SHIFT); | |
315 | size_t start_offset_in_page = (pos & ~PAGE_CACHE_MASK); | |
316 | size_t num_bytes = (PAGE_CACHE_SIZE - start_offset_in_page); | |
317 | size_t total_remaining_bytes = ((offset + size) - pos); | |
318 | ||
319 | if (num_bytes > total_remaining_bytes) | |
320 | num_bytes = total_remaining_bytes; | |
02bd9799 | 321 | ecryptfs_page = ecryptfs_get_locked_page(ecryptfs_inode, |
16a72c45 | 322 | ecryptfs_page_idx); |
da0102a1 MH |
323 | if (IS_ERR(ecryptfs_page)) { |
324 | rc = PTR_ERR(ecryptfs_page); | |
325 | printk(KERN_ERR "%s: Error getting page at " | |
326 | "index [%ld] from eCryptfs inode " | |
18d1dbf1 | 327 | "mapping; rc = [%d]\n", __func__, |
da0102a1 MH |
328 | ecryptfs_page_idx, rc); |
329 | goto out; | |
330 | } | |
da0102a1 MH |
331 | ecryptfs_page_virt = kmap_atomic(ecryptfs_page, KM_USER0); |
332 | memcpy((data + data_offset), | |
333 | ((char *)ecryptfs_page_virt + start_offset_in_page), | |
334 | num_bytes); | |
335 | kunmap_atomic(ecryptfs_page_virt, KM_USER0); | |
16a72c45 MH |
336 | flush_dcache_page(ecryptfs_page); |
337 | SetPageUptodate(ecryptfs_page); | |
338 | unlock_page(ecryptfs_page); | |
da0102a1 MH |
339 | page_cache_release(ecryptfs_page); |
340 | pos += num_bytes; | |
341 | data_offset += num_bytes; | |
342 | } | |
343 | out: | |
344 | return rc; | |
345 | } | |
7896b631 | 346 | #endif /* 0 */ |