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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 | * | |
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 | { | |
f61500e0 | 42 | struct file *lower_file; |
da0102a1 | 43 | mm_segment_t fs_save; |
96a7b9c2 | 44 | ssize_t rc; |
da0102a1 | 45 | |
f61500e0 TH |
46 | lower_file = ecryptfs_inode_to_private(ecryptfs_inode)->lower_file; |
47 | if (!lower_file) | |
48 | return -EIO; | |
da0102a1 MH |
49 | fs_save = get_fs(); |
50 | set_fs(get_ds()); | |
f61500e0 | 51 | rc = vfs_write(lower_file, data, size, &offset); |
da0102a1 | 52 | set_fs(fs_save); |
da0102a1 MH |
53 | mark_inode_dirty_sync(ecryptfs_inode); |
54 | return rc; | |
55 | } | |
56 | ||
57 | /** | |
58 | * ecryptfs_write_lower_page_segment | |
59 | * @ecryptfs_inode: The eCryptfs inode | |
60 | * @page_for_lower: The page containing the data to be written to the | |
61 | * lower file | |
62 | * @offset_in_page: The offset in the @page_for_lower from which to | |
63 | * start writing the data | |
64 | * @size: The amount of data from @page_for_lower to write to the | |
65 | * lower file | |
66 | * | |
67 | * Determines the byte offset in the file for the given page and | |
68 | * offset within the page, maps the page, and makes the call to write | |
69 | * the contents of @page_for_lower to the lower inode. | |
70 | * | |
71 | * Returns zero on success; non-zero otherwise | |
72 | */ | |
73 | int ecryptfs_write_lower_page_segment(struct inode *ecryptfs_inode, | |
74 | struct page *page_for_lower, | |
75 | size_t offset_in_page, size_t size) | |
76 | { | |
77 | char *virt; | |
78 | loff_t offset; | |
79 | int rc; | |
80 | ||
8a146a2b | 81 | offset = ((((loff_t)page_for_lower->index) << PAGE_CACHE_SHIFT) |
d6a13c17 | 82 | + offset_in_page); |
da0102a1 MH |
83 | virt = kmap(page_for_lower); |
84 | rc = ecryptfs_write_lower(ecryptfs_inode, virt, offset, size); | |
96a7b9c2 TH |
85 | if (rc > 0) |
86 | rc = 0; | |
da0102a1 MH |
87 | kunmap(page_for_lower); |
88 | return rc; | |
89 | } | |
90 | ||
91 | /** | |
92 | * ecryptfs_write | |
48c1e44a | 93 | * @ecryptfs_inode: The eCryptfs file into which to write |
da0102a1 MH |
94 | * @data: Virtual address where data to write is located |
95 | * @offset: Offset in the eCryptfs file at which to begin writing the | |
96 | * data from @data | |
97 | * @size: The number of bytes to write from @data | |
98 | * | |
99 | * Write an arbitrary amount of data to an arbitrary location in the | |
100 | * eCryptfs inode page cache. This is done on a page-by-page, and then | |
101 | * by an extent-by-extent, basis; individual extents are encrypted and | |
102 | * written to the lower page cache (via VFS writes). This function | |
103 | * takes care of all the address translation to locations in the lower | |
104 | * filesystem; it also handles truncate events, writing out zeros | |
105 | * where necessary. | |
106 | * | |
107 | * Returns zero on success; non-zero otherwise | |
108 | */ | |
48c1e44a | 109 | int ecryptfs_write(struct inode *ecryptfs_inode, char *data, loff_t offset, |
da0102a1 MH |
110 | size_t size) |
111 | { | |
112 | struct page *ecryptfs_page; | |
13a791b4 | 113 | struct ecryptfs_crypt_stat *crypt_stat; |
da0102a1 | 114 | char *ecryptfs_page_virt; |
13a791b4 | 115 | loff_t ecryptfs_file_size = i_size_read(ecryptfs_inode); |
da0102a1 MH |
116 | loff_t data_offset = 0; |
117 | loff_t pos; | |
118 | int rc = 0; | |
119 | ||
13a791b4 | 120 | crypt_stat = &ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat; |
7a3f595c ES |
121 | /* |
122 | * if we are writing beyond current size, then start pos | |
123 | * at the current size - we'll fill in zeros from there. | |
124 | */ | |
da0102a1 MH |
125 | if (offset > ecryptfs_file_size) |
126 | pos = ecryptfs_file_size; | |
127 | else | |
128 | pos = offset; | |
129 | while (pos < (offset + size)) { | |
130 | pgoff_t ecryptfs_page_idx = (pos >> PAGE_CACHE_SHIFT); | |
131 | size_t start_offset_in_page = (pos & ~PAGE_CACHE_MASK); | |
132 | size_t num_bytes = (PAGE_CACHE_SIZE - start_offset_in_page); | |
133 | size_t total_remaining_bytes = ((offset + size) - pos); | |
134 | ||
135 | if (num_bytes > total_remaining_bytes) | |
136 | num_bytes = total_remaining_bytes; | |
137 | if (pos < offset) { | |
7a3f595c | 138 | /* remaining zeros to write, up to destination offset */ |
da0102a1 MH |
139 | size_t total_remaining_zeros = (offset - pos); |
140 | ||
141 | if (num_bytes > total_remaining_zeros) | |
142 | num_bytes = total_remaining_zeros; | |
143 | } | |
02bd9799 | 144 | ecryptfs_page = ecryptfs_get_locked_page(ecryptfs_inode, |
16a72c45 | 145 | ecryptfs_page_idx); |
da0102a1 MH |
146 | if (IS_ERR(ecryptfs_page)) { |
147 | rc = PTR_ERR(ecryptfs_page); | |
148 | printk(KERN_ERR "%s: Error getting page at " | |
149 | "index [%ld] from eCryptfs inode " | |
18d1dbf1 | 150 | "mapping; rc = [%d]\n", __func__, |
da0102a1 MH |
151 | ecryptfs_page_idx, rc); |
152 | goto out; | |
153 | } | |
da0102a1 | 154 | ecryptfs_page_virt = kmap_atomic(ecryptfs_page, KM_USER0); |
7a3f595c ES |
155 | |
156 | /* | |
157 | * pos: where we're now writing, offset: where the request was | |
158 | * If current pos is before request, we are filling zeros | |
159 | * If we are at or beyond request, we are writing the *data* | |
160 | * If we're in a fresh page beyond eof, zero it in either case | |
161 | */ | |
162 | if (pos < offset || !start_offset_in_page) { | |
163 | /* We are extending past the previous end of the file. | |
164 | * Fill in zero values to the end of the page */ | |
165 | memset(((char *)ecryptfs_page_virt | |
166 | + start_offset_in_page), 0, | |
167 | PAGE_CACHE_SIZE - start_offset_in_page); | |
168 | } | |
169 | ||
170 | /* pos >= offset, we are now writing the data request */ | |
da0102a1 MH |
171 | if (pos >= offset) { |
172 | memcpy(((char *)ecryptfs_page_virt | |
173 | + start_offset_in_page), | |
174 | (data + data_offset), num_bytes); | |
175 | data_offset += num_bytes; | |
da0102a1 MH |
176 | } |
177 | kunmap_atomic(ecryptfs_page_virt, KM_USER0); | |
178 | flush_dcache_page(ecryptfs_page); | |
16a72c45 MH |
179 | SetPageUptodate(ecryptfs_page); |
180 | unlock_page(ecryptfs_page); | |
13a791b4 TH |
181 | if (crypt_stat->flags & ECRYPTFS_ENCRYPTED) |
182 | rc = ecryptfs_encrypt_page(ecryptfs_page); | |
183 | else | |
184 | rc = ecryptfs_write_lower_page_segment(ecryptfs_inode, | |
185 | ecryptfs_page, | |
186 | start_offset_in_page, | |
187 | data_offset); | |
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) { | |
13a791b4 TH |
197 | i_size_write(ecryptfs_inode, (offset + size)); |
198 | if (crypt_stat->flags & ECRYPTFS_ENCRYPTED) { | |
199 | rc = ecryptfs_write_inode_size_to_metadata( | |
200 | ecryptfs_inode); | |
201 | if (rc) { | |
202 | printk(KERN_ERR "Problem with " | |
203 | "ecryptfs_write_inode_size_to_metadata; " | |
204 | "rc = [%d]\n", rc); | |
205 | goto out; | |
206 | } | |
da0102a1 MH |
207 | } |
208 | } | |
209 | out: | |
210 | return rc; | |
211 | } | |
212 | ||
213 | /** | |
214 | * ecryptfs_read_lower | |
215 | * @data: The read data is stored here by this function | |
216 | * @offset: Byte offset in the lower file from which to read the data | |
217 | * @size: Number of bytes to read from @offset of the lower file and | |
218 | * store into @data | |
219 | * @ecryptfs_inode: The eCryptfs inode | |
220 | * | |
221 | * Read @size bytes of data at byte offset @offset from the lower | |
222 | * inode into memory location @data. | |
223 | * | |
96a7b9c2 | 224 | * Returns bytes read on success; 0 on EOF; less than zero on error |
da0102a1 MH |
225 | */ |
226 | int ecryptfs_read_lower(char *data, loff_t offset, size_t size, | |
227 | struct inode *ecryptfs_inode) | |
228 | { | |
f61500e0 | 229 | struct file *lower_file; |
da0102a1 | 230 | mm_segment_t fs_save; |
96a7b9c2 | 231 | ssize_t rc; |
da0102a1 | 232 | |
f61500e0 TH |
233 | lower_file = ecryptfs_inode_to_private(ecryptfs_inode)->lower_file; |
234 | if (!lower_file) | |
235 | return -EIO; | |
da0102a1 MH |
236 | fs_save = get_fs(); |
237 | set_fs(get_ds()); | |
f61500e0 | 238 | rc = vfs_read(lower_file, data, size, &offset); |
da0102a1 | 239 | set_fs(fs_save); |
da0102a1 MH |
240 | return rc; |
241 | } | |
242 | ||
243 | /** | |
244 | * ecryptfs_read_lower_page_segment | |
245 | * @page_for_ecryptfs: The page into which data for eCryptfs will be | |
246 | * written | |
247 | * @offset_in_page: Offset in @page_for_ecryptfs from which to start | |
248 | * writing | |
249 | * @size: The number of bytes to write into @page_for_ecryptfs | |
250 | * @ecryptfs_inode: The eCryptfs inode | |
251 | * | |
252 | * Determines the byte offset in the file for the given page and | |
253 | * offset within the page, maps the page, and makes the call to read | |
254 | * the contents of @page_for_ecryptfs from the lower inode. | |
255 | * | |
256 | * Returns zero on success; non-zero otherwise | |
257 | */ | |
258 | int ecryptfs_read_lower_page_segment(struct page *page_for_ecryptfs, | |
259 | pgoff_t page_index, | |
260 | size_t offset_in_page, size_t size, | |
261 | struct inode *ecryptfs_inode) | |
262 | { | |
263 | char *virt; | |
264 | loff_t offset; | |
265 | int rc; | |
266 | ||
d6a13c17 | 267 | offset = ((((loff_t)page_index) << PAGE_CACHE_SHIFT) + offset_in_page); |
da0102a1 MH |
268 | virt = kmap(page_for_ecryptfs); |
269 | rc = ecryptfs_read_lower(virt, offset, size, ecryptfs_inode); | |
96a7b9c2 TH |
270 | if (rc > 0) |
271 | rc = 0; | |
da0102a1 | 272 | kunmap(page_for_ecryptfs); |
16a72c45 | 273 | flush_dcache_page(page_for_ecryptfs); |
da0102a1 MH |
274 | return rc; |
275 | } | |
276 | ||
7896b631 | 277 | #if 0 |
da0102a1 MH |
278 | /** |
279 | * ecryptfs_read | |
280 | * @data: The virtual address into which to write the data read (and | |
281 | * possibly decrypted) from the lower file | |
282 | * @offset: The offset in the decrypted view of the file from which to | |
283 | * read into @data | |
284 | * @size: The number of bytes to read into @data | |
285 | * @ecryptfs_file: The eCryptfs file from which to read | |
286 | * | |
287 | * Read an arbitrary amount of data from an arbitrary location in the | |
288 | * eCryptfs page cache. This is done on an extent-by-extent basis; | |
289 | * individual extents are decrypted and read from the lower page | |
290 | * cache (via VFS reads). This function takes care of all the | |
291 | * address translation to locations in the lower filesystem. | |
292 | * | |
293 | * Returns zero on success; non-zero otherwise | |
294 | */ | |
295 | int ecryptfs_read(char *data, loff_t offset, size_t size, | |
296 | struct file *ecryptfs_file) | |
297 | { | |
02bd9799 | 298 | struct inode *ecryptfs_inode = ecryptfs_file->f_dentry->d_inode; |
da0102a1 MH |
299 | struct page *ecryptfs_page; |
300 | char *ecryptfs_page_virt; | |
02bd9799 | 301 | loff_t ecryptfs_file_size = i_size_read(ecryptfs_inode); |
da0102a1 MH |
302 | loff_t data_offset = 0; |
303 | loff_t pos; | |
304 | int rc = 0; | |
305 | ||
306 | if ((offset + size) > ecryptfs_file_size) { | |
307 | rc = -EINVAL; | |
308 | printk(KERN_ERR "%s: Attempt to read data past the end of the " | |
309 | "file; offset = [%lld]; size = [%td]; " | |
310 | "ecryptfs_file_size = [%lld]\n", | |
18d1dbf1 | 311 | __func__, offset, size, ecryptfs_file_size); |
da0102a1 MH |
312 | goto out; |
313 | } | |
314 | pos = offset; | |
315 | while (pos < (offset + size)) { | |
316 | pgoff_t ecryptfs_page_idx = (pos >> PAGE_CACHE_SHIFT); | |
317 | size_t start_offset_in_page = (pos & ~PAGE_CACHE_MASK); | |
318 | size_t num_bytes = (PAGE_CACHE_SIZE - start_offset_in_page); | |
319 | size_t total_remaining_bytes = ((offset + size) - pos); | |
320 | ||
321 | if (num_bytes > total_remaining_bytes) | |
322 | num_bytes = total_remaining_bytes; | |
02bd9799 | 323 | ecryptfs_page = ecryptfs_get_locked_page(ecryptfs_inode, |
16a72c45 | 324 | ecryptfs_page_idx); |
da0102a1 MH |
325 | if (IS_ERR(ecryptfs_page)) { |
326 | rc = PTR_ERR(ecryptfs_page); | |
327 | printk(KERN_ERR "%s: Error getting page at " | |
328 | "index [%ld] from eCryptfs inode " | |
18d1dbf1 | 329 | "mapping; rc = [%d]\n", __func__, |
da0102a1 MH |
330 | ecryptfs_page_idx, rc); |
331 | goto out; | |
332 | } | |
da0102a1 MH |
333 | ecryptfs_page_virt = kmap_atomic(ecryptfs_page, KM_USER0); |
334 | memcpy((data + data_offset), | |
335 | ((char *)ecryptfs_page_virt + start_offset_in_page), | |
336 | num_bytes); | |
337 | kunmap_atomic(ecryptfs_page_virt, KM_USER0); | |
16a72c45 MH |
338 | flush_dcache_page(ecryptfs_page); |
339 | SetPageUptodate(ecryptfs_page); | |
340 | unlock_page(ecryptfs_page); | |
da0102a1 MH |
341 | page_cache_release(ecryptfs_page); |
342 | pos += num_bytes; | |
343 | data_offset += num_bytes; | |
344 | } | |
345 | out: | |
346 | return rc; | |
347 | } | |
7896b631 | 348 | #endif /* 0 */ |